JP2007100071A - Ink set and method and apparatus for recording image - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the formation of high quality and high definition images at a high speed with excellent ink discharge stability. <P>SOLUTION: An ink set comprising an ink 120 comprising an organic pigment, a water-soluble organic solvent and water and a treating liquid 110 which is applied to a recording medium in advance before applying the ink 120 to the recording medium and produces an agglomerate upon contact with the ink, in which the ink 120 contains a low molecular weight dispersant having a molecular weight of 2,000 or lower, and polymer fine particles. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink set, an image recording method, and an apparatus, and more particularly, to an ink jet ink set, an image recording method, and an apparatus that have excellent ink ejection stability and are suitable for high-speed printing.

  In recent years, inkjet recording technology has advanced rapidly, and development in the printing field has been considered. As a result, the current inkjet printing technology has been able to form high-definition and high-definition images comparable to silver salt photographs. However, for further application to the printing field, high-speed printing and the suitability of ink and recording medium become issues.

  In the printing field, art paper, coated paper, etc. (hereinafter referred to as printing paper) are usually used. These printing papers have the property of not easily absorbing the liquid component (especially water) in the ink. For this reason, when the current water-based ink-jet ink is used, there is a problem that the ink oozes on the printing paper and the image quality is greatly deteriorated.

  For this reason, in order to realize high-speed printing, an operation for quickly removing the solvent by heat drying after printing has been required. However, heat drying is difficult because it consumes a large amount of energy, so it has become essential to develop high-concentration pigment inks for the purpose of reducing the drying load.

  On the other hand, as a recording method for suppressing ink bleeding, there is a shuttle system which is the mainstream of current ink jet recording methods. In this shuttle method, after an ink dot is first ejected and before the adjacent dot is ejected, it takes time to soak the ink that has been ejected first, and the dot coalesced with the adjacent dot (hereinafter referred to as droplet ejection). This is a method of suppressing interference). However, there is a problem that printing takes a long time and high-speed printing is difficult.

  In addition to this shuttle method, there is a page width one-pass method capable of high-speed printing. This method is relatively advantageous for high-speed printing because the time until the adjacent dots are hit is very short. However, there is a problem in that droplet ejection interference easily occurs and image quality is likely to deteriorate.

  As a means for solving this problem, a two-liquid reaction system has been proposed in which, when contacted with ink, a treatment liquid that forms an agglomerate with ink is ejected or applied to a recording medium, thereby avoiding droplet ejection buffering. It has come to be.

  For example, Patent Document 1 discloses an ink jet recording method in which an ink containing a pigment, polymer fine particles, and the like and a treatment liquid containing a reactive agent that forms an aggregate when contacted with the ink are combined. According to this, it is described that the abrasion resistance, water resistance, ink ejection stability, and the like are improved.

Patent Document 2 discloses an ink containing a pigment, a resin emulsion, and the like. According to this, it is described that the storage stability of the ink is excellent.
JP 2000-272220 A JP 2000-290553 A

  However, when the polymer dispersant is used for the ink as in Patent Documents 1 and 2 (particularly in the case of a high concentration pigment ink), the addition of polymer fine particles or resin emulsion significantly increases the viscosity of the ink. End up. Therefore, there is a problem that ink cannot be discharged satisfactorily in inkjet. Furthermore, high-speed printing has been difficult because droplet ejection interference cannot be sufficiently avoided.

  The present invention has been made in view of such circumstances, and provides an ink set, an image recording method, and an apparatus that are excellent in ink ejection stability and can form high-quality images at high speed at high speed.

  In order to achieve the above object, claim 1 of the present invention is an ink containing at least an organic pigment, a water-soluble organic solvent, and water, and is applied to the recording medium in advance before applying the ink to the recording medium. An ink set comprising a treatment liquid that generates aggregates when contacted with the ink, wherein the ink contains a low-molecular dispersant having a molecular weight of 2000 or less and polymer fine particles. An ink set is provided.

  According to the first aspect of the present invention, since the pigment is dispersed using the low molecular dispersant instead of the polymer dispersant, the viscosity of the high concentration ink can be lowered. Further, since the polymer fine particles are added to the ink, it is possible to ensure the fixability, abrasion resistance, and water resistance of the ink to the recording medium. This makes it possible to produce a high-concentration and low-viscosity ink without impairing the fixability, rubbing resistance, and water resistance, so that the ink discharge stability is excellent, and high-quality and high-definition images are produced at high speed. Can be formed. In addition, since the agglomerate is generated by contacting with the treatment liquid, it is possible to avoid droplet ejection interference due to ink bleeding, and high-speed printing is possible.

  In claim 1, the molecular weight of the low molecular weight dispersant can be determined by calculation from the composition formula. Moreover, 100-2000 are preferable and, as for the molecular weight of a low molecular dispersing agent, 200-2000 are more preferable.

  A second aspect is characterized in that, in the first aspect, the treatment liquid is acidic.

  According to a second aspect of the present invention, the ink is brought into contact with an acidic treatment liquid, and the acidity (pH) of the ink is changed to cause an aggregation reaction. In this way, since ink forms aggregates, it is possible to suppress droplet ejection interference. Further, since the pH change of the ink is caused by the movement of hydrogen ions, which are the smallest atoms, the aggregation reaction occurs at a high speed. Therefore, high-speed printing can be performed. In addition, it is preferable that the pH of a process liquid is the range of 1-6, It is more preferable that it is the range of 2-5, It is further more preferable that it is the range of 3-5.

  A third aspect is characterized in that, in the first or second aspect, the pKa of the dissociation constant Ka of the low molecular dispersant is 3 or more.

In claim 3, pKa is an acid dissociation reaction (HA → H ⁺ + A ⁻ , H ⁺ : hydrogen ion molar concentration, A ⁻ : anionic group molar concentration), and the dissociation constant is Ka = [H ⁺ ] [A ⁻ ] / [
HA], represented by pKa = −log (Ka).

  According to claim 3, in theory, 50% or more of the anionic groups of the low molecular weight dispersant are brought into a non-dissociated state by contacting with a treatment liquid having a pH of about 3 (that is, equivalent to pKa). Occur. Therefore, ink droplet interference can be suppressed, and high-speed printing is possible. Further, at this time, the water resistance of the anionic group of the low molecular dispersant is lowered, so that the water resistance is improved.

  Actually, when the pKa of the low molecular dispersant is lower than 3, the aggregation reaction hardly proceeds unless the pH of the acidic treatment liquid is lower than 3. However, if the pH of the processing solution is too low (becomes a strong acid), there is a risk that the inkjet head is corroded. For this reason, in order to ensure the durability of the head, it is preferable to use the low molecular dispersant of claim 3.

  A fourth aspect of the present invention is characterized in that in any one of the first to third aspects, the chemical structure of the low molecular weight dispersant includes a carboxylic acid group or a salt thereof.

  According to the fourth aspect, since the pKa range of the low molecular dispersant according to the third aspect is satisfied, the droplet ejection interference is suppressed and high-speed printing is possible. Moreover, since the low molecular dispersant containing a carboxylic acid group is easy to synthesize and produce, an ink can be provided at low cost.

  A fifth aspect of the present invention is characterized in that, in any one of the first to fourth aspects, the low molecular dispersant is represented by the general formula (1).

A sixth aspect of the present invention is characterized in that in the fifth aspect, L ^{1 in the} general formula (1) is an amide group, a sulfonamide group, an ester group, an ether group, or a sulfide group.

  A seventh aspect of the present invention is characterized in that, in any one of the first to sixth aspects, the low molecular dispersant is represented by the general formula (2) or (3).

  Claims 5 to 7 define preferred structures of the low molecular dispersant of the present invention. By adding the low molecular dispersant of claims 5 to 7, preferably the low molecular dispersant of claim 7, to the ink, an ink excellent in dispersibility and ejection stability of the organic pigment can be obtained.

  An eighth aspect is characterized in that, in any one of the first to seventh aspects, a glass transition temperature Tg of the polymer fine particles is 30 ° C. or higher.

  When the glass transition temperature Tg of the polymer fine particles is less than 30 ° C., the polymer fine particles are softened at room temperature, so that they are fused or formed to form coarse foreign matters in the inkjet head. For this reason, clogging of the head occurs, and ink ejection stability is impaired.

  According to the eighth aspect, since polymer fine particles having a glass transition temperature Tg of room temperature (about 30 ° C. or lower) or higher are used, ink can be discharged well even at room temperature.

  A ninth aspect is characterized in that, in any one of the first to eighth aspects, the polymer fine particles are styrene latex or acrylic latex.

  By using the polymer latex of the ninth aspect, it is possible to ensure fixability, abrasion resistance and water resistance even with a low viscosity ink. Therefore, the ink can be discharged well, and a high-quality and high-definition image can be formed. The styrene latex is preferably a styrene-butadiene copolymer or a styrene-isoprene copolymer latex, and more preferably a styrene-butadiene copolymer.

  A tenth aspect of the present invention is characterized in that, in any one of the first to ninth aspects, a mass ratio P / C between the mass P of the polymer fine particles and the mass C of the organic pigment is 0.5 to 4.0. And

When the amount of the polymer fine particles added to the organic pigment contained in the ink is too small, the abrasion resistance and the fixing property are lowered. On the other hand, when the addition amount of the polymer fine particles is too large, the viscosity of the ink increases rapidly, and the discharge performance deteriorates. According to the tenth aspect, it is possible to improve the ejection stability of the ink while ensuring the rub resistance and the fixing property of the ink.

  An eleventh aspect is characterized in that in any one of the first to tenth aspects, the ink contains a fluorinated surfactant.

  According to the eleventh aspect, since the fluorinated surfactant is added, it is possible to improve the abrasion resistance and ejection stability of the ink. Further, in order to obtain good ink ejection stability, it is preferable to add a fluorine-based surfactant so that the surface tension of the ink is adjusted to a range of 20 to 60 mN / m.

  A twelfth aspect is characterized in that the ink set according to any one of the first to eleventh aspects is an ink jet ink set.

  According to the twelfth aspect, in the ink jet, it is possible to stably eject the ink and suppress the droplet ejection interference. Therefore, high-quality and high-definition high-speed printing can be realized.

  According to a thirteenth aspect of the present invention, there is provided an image recording method using the ink set according to any one of the first to twelfth aspects, wherein a treatment liquid for the ink set is applied to a recording medium. Then, an image recording method is provided, wherein an image is formed by applying the ink of the ink set to the treatment liquid.

  According to a thirteenth aspect of the present invention, an image is formed by bringing a low-viscosity ink excellent in ejection stability, which is the ink set of the present invention, and a processing liquid into contact with each other on a recording medium to form an aggregate. I made it. Therefore, the ink ejection stability is excellent, and a high-speed, high-quality and high-definition image can be formed.

  A fourteenth aspect of the invention is characterized in that, in the thirteenth aspect, the treatment liquid is acidic and the acidity of the ink changes due to contact with the treatment liquid to generate an aggregate.

  According to the fourteenth aspect, the agglomeration reaction can be rapidly performed by bringing the ink and the treatment liquid into contact with each other. Therefore, droplet ejection interference can be suppressed. Further, the pH change of the treatment liquid is the same as that of the second aspect.

  A fifteenth aspect is characterized in that in the thirteenth or fourteenth aspect, the image recording method is an ink jet recording method.

  According to the fifteenth aspect, even in the case of ink jetting, ink can be stably ejected, and droplet ejection interference can be reduced by contact with the treatment liquid. Therefore, high-quality and high-definition high-speed printing is possible.

  According to a sixteenth aspect of the present invention, there is provided an image recording apparatus using the ink set according to any one of the first to twelfth aspects, wherein the treatment liquid of the ink set is applied to a recording medium. First application means, second application means for applying the ink of the ink set to the treatment liquid, and heating means for heating the aggregate formed by contacting the ink and the treatment liquid. Provided is an image recording apparatus comprising the above.

  The sixteenth aspect is an image recording apparatus using the ink set of the present invention. According to the sixteenth aspect, the polymer fine particles in the aggregate are dried and cured by heating the aggregate to a predetermined temperature or higher by the heating means. As a result, the polymer fine particles dispersed together with the organic pigment can be bound together in a film shape, and the fixing property, abrasion resistance, water resistance, etc. to the recording medium can be improved.

  According to the ink set of the present invention, an ink having a high concentration and a low viscosity can be produced without impairing the fixing property, rubbing resistance and water resistance. Therefore, according to the image recording method and apparatus using the ink of the present invention, the ink ejection stability is excellent, and a high-quality and high-definition image can be formed at high speed.

  First, the ink set of the present invention will be described in detail.

[Ink configuration]
(Low molecular dispersant)
The low molecular dispersant used in the present embodiment is added for the purpose of stably dispersing the organic pigment in an aqueous solvent while keeping the ink at a low viscosity. The low molecular dispersant used in the present embodiment is a low molecular dispersant having a molecular weight of 2000 or less. Moreover, 100-2000 are preferable and, as for the molecular weight of a low molecular dispersing agent, 200-2000 are more preferable.

  In the present embodiment, the low molecular weight dispersant has a structure including a hydrophilic group and a hydrophobic group. In addition, the hydrophilic group and the hydrophobic group may be independently contained in one molecule or more, and may have a plurality of types of hydrophilic groups and hydrophobic groups. In addition, a linking group for linking a hydrophilic group and a hydrophobic group can be appropriately included.

  The hydrophilic group is anionic, cationic, nonionic, or a betaine type combining these.

  The anionic group may be any as long as it has a negative charge, but is preferably a phosphate group, phosphonic acid group, phosphinic acid group, sulfuric acid group, sulfonic acid group, sulfinic acid group or carboxylic acid group. More preferably a phosphoric acid group or a carboxylic acid group, and even more preferably a carboxylic acid group.

  The cationic group may be any as long as it has a positive charge, but is preferably an organic cationic substituent, and more preferably a nitrogen or phosphorus cationic group. Further, it is more preferably a pyridinium cation or an ammonium cation.

  Examples of the nonionic group include polyethylene oxide, polyglycerin, a part of sugar unit, and the like.

  In the present embodiment, the hydrophilic group is preferably an anionic group. The anionic group is preferably a phosphoric acid group, a phosphonic acid group, a phosphinic acid group, a sulfuric acid group, a sulfonic acid group, a sulfinic acid group or a carboxylic acid group, more preferably a phosphoric acid group or a carboxylic acid group. More preferably, it is a carboxylic acid group.

  Moreover, when a low molecular dispersing agent has an anionic hydrophilic group, it is preferable that pKa is 3 or more from a viewpoint of making it contact with an acidic process liquid and promoting an aggregation reaction. In the present invention, the pKa of the low molecular weight dispersant is a solution obtained by dissolving 1 mmol / L of the low molecular weight dispersant in a tetrahydrofuran / water (tetrahydrofuran: water = 3: 2 = V / V) solution with an acid or alkaline aqueous solution. It is a value obtained experimentally from a titration curve obtained by titration. If the pKa of the low molecular dispersant is 3 or more, theoretically, 50% or more of the anionic groups are in a non-dissociated state when in contact with a treatment solution having a pH of about 3. Accordingly, the water solubility of the low molecular weight dispersant is remarkably lowered, and an agglomeration reaction occurs. That is, the aggregation reactivity is improved. Also from this viewpoint, the low molecular dispersant preferably has a carboxylic acid group as an anionic group.

The hydrophobic group has a hydrocarbon-based structure, a fluorocarbon-based structure, a silicone-based structure, or the like, and is particularly preferably a hydrocarbon-based structure. Further, these hydrophobic groups may have a linear structure or a branched structure. The hydrophobic group may have a single chain structure or a chain structure of more than this, and may have a plurality of types of hydrophobic groups in the case of a structure of two or more chains.

  The hydrophobic group is preferably a hydrocarbon group having 2 to 24 carbon atoms, more preferably a hydrocarbon group having 4 to 24 carbon atoms, and further preferably a hydrocarbon group having 6 to 20 carbon atoms.

  The amount of the low molecular dispersant added is preferably within a range in which the pigment can be uniformly dispersed in an aqueous solvent and the ink can be stably ejected. The mass C of the organic pigment having the mass B of the low molecular dispersant is The mass ratio B / C with respect to is preferably 0.0001 to 1, more preferably 0.0001 to 0.5, and still more preferably 0.0001 to 0.2. The viscosity of the ink is preferably in the range of 1 to 30 mPa · s, more preferably in the range of 1 to 20 mPa · s, still more preferably in the range of 2 to 15 mPa · s, and particularly preferably in the range of 2 to 10 mPa · s.

Specific examples of the low molecular weight dispersant suitably used in the present embodiment include compounds represented by the following general formulas (1), (2), and (3). The present invention includes the following specific examples. It is not limited to examples. As will be described later, among the low molecular dispersants represented by the general formulas (1) to (3), the low molecular dispersants represented by the general formulas (2) and (3) are preferable. The low molecular weight dispersant represented is more preferred.
General formula (1)

In the general formula (1), R ¹ represents a substituent, and R ² and R ³ each represent a hydrogen atom or a substituent. However, the sum of the carbon numbers of R ¹ , R ² , and R ³ is 13 or more, and preferably 16 or more. M represents a hydrogen atom or a monovalent cation. L ¹ represents a single bond or a divalent linking group, and the divalent linking group is preferably an amide group, a sulfonamide group, an ester group, an ether group, or a sulfide group, and is an amide group. It is more preferable.

  The following substituents (hereinafter referred to as “substituent T”) can be applied to the above-described substituents. Specific examples of the substituent T include an alkyl group [representing a linear, branched, or cyclic substituted or unsubstituted alkyl group. These are alkyl groups (preferably alkyl groups having 1 to 30 carbon atoms such as methyl, ethyl, n-propyl, isopropyl, t-butyl, s-butyl, n-hexyl, n-octyl, n-lauryl), cycloalkyl Group (preferably containing a substituted or unsubstituted cycloalkyl group having 5 to 30 carbon atoms, such as cyclohexyl, cyclopentyl, 4-n-dodecylcyclohexyl), an aryl group (preferably substituted or unsubstituted having 6 to 30 carbon atoms) Aryl groups such as phenyl, p-dodecylphenyl, naphthyl, p-hexadecyloxyphenyl), heterocyclic groups (preferably 5- or 6-membered substituted or unsubstituted aromatic or non-aromatic heterocyclic compounds It is a monovalent group from which one hydrogen atom has been removed, and more preferably a 5-membered member having 3 to 30 carbon atoms. Or a 6-membered aromatic heterocyclic group such as 2-furyl, 2-thienyl, 2-pyrimidinyl, 2-benzothiazolyl, pyridyl), hydroxyl group, alkoxy group (preferably having 1 to 30 carbon atoms or An unsubstituted alkoxy group such as methoxy, ethoxy, isopropoxy, t-butoxy, n-octyloxy, 2-methoxyethoxy), an aryloxy group (preferably a substituted or unsubstituted aryloxy group having 6 to 30 carbon atoms, For example, phenoxy, 2-methylphenoxy, 4-t-butylphenoxy, 4-n-dodecyloxyphenoxy, 1-naphthoxy), a heterocyclic oxy group (preferably a substituted or unsubstituted heterocyclic group having 2 to 30 carbon atoms) Oxy group, 1-phenyltetrazole-5-oxy, 2-tetrahydropyranyloxy), A siloxy group (preferably a substituted or unsubstituted alkylcarbonyloxy group having 2 to 30 carbon atoms, a substituted or unsubstituted arylcarbonyloxy group having 6 to 30 carbon atoms such as acetyloxy, pivaloyloxy, stearoyloxy, benzoyloxy, p -Methoxyphenylcarbonyloxy), a carbamoyloxy group (preferably a substituted or unsubstituted carbamoyloxy group having 1 to 30 carbon atoms such as N, N-dimethylcarbamoyloxy, N, N-diethylcarbamoyloxy, morpholinocarbonyloxy, N , N-di-n-octylaminocarbonyloxy, Nn-octylcarbamoyloxy), an alkoxycarbonyloxy group (preferably a substituted or unsubstituted alkoxycarbonyloxy group having 2 to 30 carbon atoms, such as meth Xoxycarbonyloxy, ethoxycarbonyloxy, t-butoxycarbonyloxy, n-octylcarbonyloxy), aryloxycarbonyloxy groups (preferably substituted or unsubstituted aryloxycarbonyloxy groups having 7 to 30 carbon atoms, such as phenoxycarbonyloxy , P-methoxyphenoxycarbonyloxy, pn-hexadecyloxyphenoxycarbonyloxy), amino group (preferably amino group, substituted or unsubstituted alkylamino group having 1 to 30 carbon atoms, substitution having 6 to 30 carbon atoms) Or an unsubstituted arylamino [anilino] group such as amino, methylamino, dimethylamino, anilino, N-methyl-anilino, diphenylamino), an acylamino group (preferably a substituted or unsubstituted alkyl group having 2 to 30 carbon atoms). Carbonylamino group, substituted or unsubstituted arylcarbonylamino group having 6 to 30 carbon atoms such as acetylamino, pivaloylamino, lauroylamino, benzoylamino), aminocarbonylamino group (preferably substituted or unsubstituted having 1 to 30 carbon atoms) Aminocarbonylamino such as carbamoylamino, N, N-dimethylaminocarbonylamino, N, N-diethylaminocarbonylamino, morpholinocarbonylamino), alkoxycarbonylamino group (preferably substituted or unsubstituted alkoxycarbonyl having 2 to 30 carbon atoms) Amino groups such as methoxycarbonylamino, ethoxycarbonylamino, t-butoxycarbonylamino, n-octadecyloxycarbonylamino, N-methyl-methoxycarbonylamino), Aryloxycarbonylamino group (preferably a substituted or unsubstituted aryloxycarbonylamino group having 7 to 30 carbon atoms such as phenoxycarbonylamino, p-chlorophenoxycarbonylamino, mn-octyloxyphenoxycarbonylamino), sulfa A moylamino group (preferably a substituted or unsubstituted sulfamoylamino group having 0 to 30 carbon atoms such as sulfamoylamino, N, N-dimethylaminosulfonylamino, Nn-octylaminosulfonylamino), alkyl and Arylsulfonylamino group (preferably substituted or unsubstituted alkylsulfonylamino having 1 to 30 carbon atoms, substituted or unsubstituted arylsulfonylamino having 6 to 30 carbon atoms such as methylsulfonylamino, butylsulfonylamino, Phenylsulfonylamino, 2,3,5-trichlorophenylsulfonylamino, p-methylphenylsulfonylamino), mercapto group, alkylthio group (preferably a substituted or unsubstituted alkylthio group having 1 to 30 carbon atoms such as methylthio, ethylthio N-hexadecylthio), an arylthio group (preferably a substituted or unsubstituted arylthio having 6 to 30 carbon atoms, such as phenylthio, p-chlorophenylthio, m-methoxyphenylthio), a heterocyclic thio group (preferably having 2 to 2 carbon atoms). 30 substituted or unsubstituted heterocyclic thio groups such as 2-benzothiazolylthio, 1-phenyltetrazol-5-ylthio), sulfamoyl groups (preferably substituted or unsubstituted sulfamoyl groups having 0 to 30 carbon atoms such as N-ethylsulfamo , N- (3-dodecyloxypropyl) sulfamoyl, N, N-dimethylsulfamoyl, N-acetylsulfamoyl, N-benzoylsulfamoyl, N- (N′-phenylcarbamoyl) sulfamoyl), alkyl and Arylsulfinyl groups (preferably substituted or unsubstituted alkylsulfinyl groups having 1 to 30 carbon atoms, substituted or unsubstituted arylsulfinyl groups having 6 to 30 carbon atoms, such as methylsulfinyl, ethylsulfinyl, phenylsulfinyl, p-methylphenyl Sulfinyl), alkyl and arylsulfonyl groups (preferably substituted or unsubstituted alkylsulfonyl groups having 1 to 30 carbon atoms, substituted or unsubstituted arylsulfonyl groups having 6 to 30 carbon atoms such as methylsulfonyl, ethylsulfonyl, t- Butyl Sulfonyl, s-butylsulfonyl, phenylsulfonyl, pyridylsulfonyl, p-methylphenylsulfonyl), acyl group (preferably a substituted or unsubstituted alkylcarbonyl group having 2 to 30 carbon atoms, substituted or unsubstituted having 7 to 30 carbon atoms) An arylcarbonyl group, a heterocyclic carbonyl group bonded to the carbonyl group with a substituted or unsubstituted carbon atom having 4 to 30 carbon atoms, such as acetyl, pivaloyl, 2-chloroacetyl, stearoyl, benzoyl, pn-octyl Oxyphenylcarbonyl, 2-pyridylcarbonyl, 2-furylcarbonyl), an aryloxycarbonyl group (preferably a substituted or unsubstituted aryloxycarbonyl group having 7 to 30 carbon atoms, such as phenoxycarbonyl, o-chlorophenoxycarbonyl, m- Nitro Phenoxycarbonyl, pt-butylphenoxycarbonyl), alkoxycarbonyl group (preferably a substituted or unsubstituted alkoxycarbonyl group having 2 to 30 carbon atoms such as methoxycarbonyl, ethoxycarbonyl, t-butoxycarbonyl, n-octadecyloxycarbonyl) A carbamoyl group (preferably a substituted or unsubstituted carbamoyl having 1 to 30 carbon atoms such as carbamoyl, N-methylcarbamoyl, N, N-dimethylcarbamoyl, N, N-di-n-octylcarbamoyl, N- (methylsulfonyl) ) Carbamoyl), imide group (preferably N-succinimide, N-phthalimide).

In the general formula (1), R ¹ is a substituted group, an alkyl group, an aryl group, or a heterocyclic group and more preferably an alkyl group.

R ² represents a hydrogen atom or a substituent, preferably a substituent, and is an alkyl group, aryl group, heterocyclic group, hydroxyl group, alkoxy group, aryloxy group, heterocyclic oxy group, acylamino group, alkyl and An arylsulfonylamino group, a mercapto group, an alkylthio group, an arylthio group, a heterocyclic thio group, and a carbamoyl group are more preferable. Further, an alkoxy group, an aryloxy group, an acylamino group, an alkyl and arylsulfonylamino group, an alkylthio group, an arylthio group, and a heterocyclic thio group are more preferable, and an aryloxy group is particularly preferable.

R ³ represents a hydrogen atom or a substituent, and is preferably a hydrogen atom or an alkyl group.

  M represents a hydrogen atom or a monovalent cation. Examples of the monovalent cation include alkali metal atoms such as lithium, sodium and potassium, ammonium, quaternary ammonium, imidazolium, sulfonium, phosphonium and iodonium. Can be mentioned. As the monovalent cation, a hydrogen atom, a monovalent alkali metal atom, or a quaternary ammonium is preferable, and a hydrogen atom, lithium, sodium, or potassium is more preferable.

Moreover, it is more preferable that any one of R ^{1 to} R ³ contains one or more hetero elements.

As one of the preferable embodiments of the general formula (1), for example, R ¹ , R ² , R ³ , n, L ¹ , and M are alkyl groups, aryloxy groups, hydrogen atoms, 1, single bonds, and hydrogen atoms. There are some combinations.

  Moreover, the following compounds (1-1)-(1-27) are mentioned as a preferable example of the low molecular dispersing agent of molecular weight 2000 or less represented by General formula (1).

Also, compounds containing a substituent selected from R ^1, R ^2, R ³ groups in Table 1 can also be suitably used.

Moreover, it is preferable that L < ¹ > of General formula (1) is represented by General formula (2) and (3) which is an amide group.
General formula (2)

General formula (3)

In the general formula (2) or (3), R ¹ represents a substituent, and R ² , R ³ and R ⁴ each represent a hydrogen atom or a substituent. n represents an integer of 0 to 6. M represents a hydrogen atom or a monovalent cation and is the same as M described above. ^However, R 1 to R ⁴ is not to have a sulfonic acid group, the sum of these carbon atoms is 13 or more (preferably 140 or less). Here, the above-mentioned substituent T can be applied to the substituent.

In the general formulas (2) and (3), R ¹ represents a substituent, preferably an alkyl group, an aryl group, a heterocyclic group, an alkoxy group, an aryloxy group, a heterocyclic oxy group, or an amino group. Further, an alkyl group is more preferable, and an alkyl group having 12 or more carbon atoms is most preferable.

R ² represents a hydrogen atom or a substituent, and the substituent is preferably an alkyl group, an aryl group, a heterocyclic group, an acyl group, or a sulfonyl group, more preferably an alkyl group, and further preferably an alkyl group having 4 or less carbon atoms. . R ² is particularly preferably a hydrogen atom or a methyl group.

R ³ and R ⁴ represent a hydrogen atom or a substituent, but are preferably a hydrogen atom or an alkyl group, and more preferably a hydrogen atom.

The total number of carbon atoms of R ¹ to R ⁴ is preferably 13 to 140, 15 to 100 is more preferable.

One of preferable embodiments of the general formula (2) or (3) is, for example, that R ¹ , R ² , R ³ , R ⁴ , n, and M are an alkyl group, a methyl group, a hydrogen atom, a hydrogen atom, 2 And combinations that are hydrogen atoms.

  Moreover, as a preferable example of a low molecular weight dispersant having a molecular weight of 2000 or less represented by the general formulas (2) and (3), the following compounds (2-1) to (2-7) and a compound (3-1) To (3-6).

  Table 2 shows the molecular weights of the above compounds (1-1) to (1-27), (2-1) to (2-7), and compounds (3-1) to (3-6).

(Polymer fine particles)
The polymer fine particles used in the present embodiment are added to the ink mainly for the purpose of improving the fixing property of the ink to the recording medium and the abrasion resistance of the coated surface. Such polymer fine particles are preferably dispersed in water and a water-containing organic solvent as a polymer latex.

  The polymer latex used in the present embodiment is not particularly limited as long as it is made of a polymer of a monomer compound having an unsaturated double bond.

  Examples of the monomer include aromatic vinyl compounds, acrylic acid and its ester compounds / amide compounds, methacrylic acid and its ester compounds / amide compounds, vinyl ester compounds, vinyl cyanide compounds, olefin compounds, and diene compounds. More specifically, aromatic vinyl monomers such as styrene, 2-methylstyrene, vinyltoluene, t-butylstyrene, chlorostyrene, vinylanisole and vinylnaphthalene; acrylic acid and methyl acrylate, ethyl Acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, n-amyl acrylate, isoamyl acrylate, n-hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, deci Acrylic esters such as acrylate, dodecyl acrylate, octadecyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, glycidyl acrylate, N, N-dimethylaminoethyl acrylate; acrylamide, N, N-dimethylaminopropylacrylamide, N, N- Acrylic acid amide compounds such as dimethylacrylamide, acryloylmorpholine, N-isopropylacrylamide, N, N-diethylacrylamide; methacrylic acid and methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, n-amyl methacrylate, isoamyl Methacrylate, n-hexyl methacrylate, 2-ethylhexylme Methacrylic acid esters such as acrylate, octyl methacrylate, decyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, glycidyl methacrylate; and vinyl esters such as vinyl acetate; vinyl such as acrylonitrile and methacrylonitrile Cyanogen compounds; halogenated monomers such as vinylidene chloride and vinyl chloride; olefins such as ethylene, propylene and isopropylene; dienes such as butadiene, isoprene and chloroprene; vinyl such as vinyl ether, vinyl ketone and vinyl pyrrolidone Monomers. In order to stabilize the dispersion of the latex, it is more preferable that a monomer having a dissociable group such as acrylic acid, methacrylic acid, itaconic acid, fumaric acid, maleic acid or the like is included.

  The polymer latex is preferably a styrene latex having styrene as a constituent monomer, an acrylic latex having an acrylate ester as a constituent monomer, or a vinyl acetate latex having vinyl acetate as a constituent monomer. More preferred are styrene latex such as styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylate copolymer, and acrylic latex composed of acrylate. More preferred are styrene-based latexes, such as styrene-butadiene copolymer latex, styrene-isoprene copolymer latex, and styrene-acrylate copolymer latex, and particularly preferred is styrene-butadiene copolymer latex.

  In the styrene-butadiene copolymer, the mass ratio of the styrene monomer unit to the butadiene monomer unit is preferably 20:80 to 95: 5, more preferably 30:70 to 80:20, and 30: More preferably, it is 70-55: 45.

  Moreover, it is preferable that the ratio for which the styrene monomer unit and a butadiene monomer unit occupy with respect to the whole copolymer is 60-99 mass%.

  Moreover, it is preferable to contain 1-6 mass% of acrylic acid or methacrylic acid with respect to the sum of styrene and butadiene, and it is more preferable to contain 2-5 mass%. In addition, it is preferable that these polymer latex contains acrylic acid.

As latex of the styrene-butadiene-acrylic acid copolymer suitably used in the present embodiment, commercially available products LACSTAR-3307B, 7132C (manufactured by Dainippon Ink and Chemicals), Nipol Lx416 (manufactured by Nippon Zeon), Nalstar SBR (manufactured by Nippon A & L) and the like can be mentioned.

  Moreover, styrene which has a substituent may be sufficient as styrene, and the above-mentioned substituent T can be applied as a substituent.

  When the amount of polymer fine particles added is large relative to the ink, the effect of improving the fixability and abrasion resistance is great, but on the other hand, the viscosity of the ink increases. Therefore, the addition amount of the polymer fine particles is preferably 0.5 to 20% by mass, more preferably 1 to 20% by mass, further preferably 3 to 20% by mass, and further preferably 5 to 15% by mass with respect to the ink. .

  Therefore, when it is necessary to increase the addition amount of the polymer fine particles beyond this, it is preferable that the treatment liquid contains the polymer fine particles. The preferable content of the polymer fine particles with respect to the treatment liquid is the same as that of the ink.

  The glass transition temperature Tg of the polymer fine particles used in the present embodiment was calculated using the following formula.

[Formula 1]
1 / Tg = Σ (Xi / Tgi)
Here, it is assumed that n monomer components from i = 1 to n are copolymerized in the polymer fine particles. Xi is the weight fraction of the i-th monomer (ΣXi = 1), and Tgi is the glass transition temperature (absolute temperature) of the homopolymer of the i-th monomer. Here, Σ is the sum from i = 1 to n. In addition, the value (Tgi) of the homopolymer glass transition temperature of each monomer was determined by Polymer Handbook (3rd Edition) (J. Brandrup, EHI).
With reference to the value of Mergut (Wiley-Interscience, 1989), styrene was calculated as 100 ° C and butadiene was calculated as -85 ° C. Therefore, even if the constituent monomers are the same, Tg can be controlled by changing the composition ratio of these monomers.

  The glass transition temperature Tg of the polymer fine particles used in the present embodiment is preferably room temperature or higher, that is, 30 ° C. or higher, from the viewpoint of ink storage stability. The glass transition temperature Tg is more preferably 40 ° C. or higher, and further preferably 50 ° C. or higher. Although the glass transition temperature Tg is high, adverse effects such as stickiness of the printed sample can be considered. However, it is possible to reduce the adverse effects such as stickiness even with polymer fine particles having a high glass transition temperature Tg by heating after printing. .

  The average particle size of the polymer fine particles is preferably in the range of 10 nm to 1 μm, more preferably in the range of 10 to 500 nm, still more preferably in the range of 20 to 200 nm, and particularly preferably in the range of 50 to 200 nm. Further, the particle size distribution of the polymer fine particles is not particularly limited, and may be any one having a wide particle size distribution or a monodispersed particle size distribution. Further, two or more kinds of polymer fine particles having a monodispersed particle size distribution may be mixed and used.

(Organic pigment)
The ink used in this embodiment can be used not only for forming a single color image but also for forming a full color image. In order to form a full color image, a magenta color ink, a cyan color ink, and a yellow color ink can be used, and a black color ink may be further used to adjust the color tone. Further, red, green, blue, and white inks other than yellow, magenta, and cyan color inks, and so-called special color inks in the printing field can be used.

  Specific examples of the pigment used in the present embodiment are shown below.

  Examples of the pigment for orange or yellow include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 180, C.I. I. And CI Pigment Yellow 185.

  Examples of the magenta or red pigment include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. And CI Pigment Red 222.

  Examples of the pigment for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. Pigment Green 7 and siloxane-crosslinked aluminum phthalocyanine described in U.S. Pat. No. 4,311,775.

  Examples of black pigments include C.I. I. Pigment black 1, C.I. I. Pigment black 6, C.I. I. Pigment black 7 and the like.

  Further, the average particle diameter of the organic pigment is preferably as small as possible from the viewpoint of transparency and color reproducibility, but is preferably large from the viewpoint of light resistance. As an average particle diameter which balances these, 10-200 nm is preferable, 10-150 nm is more preferable, 10-100 nm is further more preferable. In addition, the particle size distribution of the organic pigment is not particularly limited, and may be either a wide particle size distribution or a monodispersed particle size distribution. Two or more kinds of organic pigments having a monodispersed particle size distribution may be mixed and used.

  The addition amount of the organic pigment is preferably 1 to 25% by mass, more preferably 2 to 20% by mass, further preferably 5 to 20% by mass, and particularly 5 to 15% by mass with respect to the ink. preferable.

(Water-soluble organic solvent)
The water-soluble organic solvent used in this embodiment is used for the purpose of preventing drying or promoting wetting. Further, the drying inhibitor is suitably used at the ink ejection port of the nozzle in the ink jet recording method, and prevents clogging due to drying of the ink for ink jet.

  The drying inhibitor is preferably a water-soluble organic solvent having a vapor pressure lower than that of water. Specific examples of the drying inhibitor include ethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol, thiodiglycol, dithiodiglycol, 2-methyl-1,3-propanediol, 1,2,6-hexanetriol, Polyvalent alcohols typified by acetylene glycol derivatives, glycerin, trimethylolpropane, etc., polyvalent alcohols such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol monomethyl (or ethyl) ether, triethylene glycol monoethyl (or butyl) ether Lower alkyl ethers of alcohols, 2-pyrrolidone, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, heterocyclic rings such as N-ethylmorpholine, sulfolane, dimethyls Sulfoxide, sulfur-containing compounds such as 3-sulfolene, diacetone alcohol, polyfunctional compounds such as diethanolamine, and urea derivatives. Of these, the drying inhibitor is preferably a polyhydric alcohol such as glycerin or diethylene glycol. Moreover, said drying inhibitor may be used independently or may be used together 2 or more types. These drying inhibitors are preferably contained in the ink in an amount of 10 to 50% by mass.

  Further, the penetration accelerator is preferably used for the purpose of allowing the ink to penetrate better into the recording medium (printing paper). Specific examples of penetration enhancers include alcohols such as ethanol, isopropanol, butanol, di (tri) ethylene glycol monobutyl ether, 1,2-hexanediol, sodium lauryl sulfate, sodium oleate, and nonionic surfactants. Etc. can be used suitably. These penetration enhancers exhibit a sufficient effect when contained in the ink composition in an amount of 5 to 30% by mass. Further, it is preferable that the penetration enhancer is used within a range of an addition amount that does not cause printing bleeding and paper loss (print through).

  In addition to the above, the water-soluble organic solvent is also used for adjusting the viscosity. Specific examples of water-soluble organic solvents that can be used to adjust the viscosity include alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, sec-butanol, t-butanol, pentanol, hexanol, Cyclohexanol, benzyl alcohol), polyhydric alcohols (for example, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, Thiodiglycol), glycol derivatives (eg, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether) Tellurium, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, triethylene glycol monomethyl ether, ethylene glycol diacetate, ethylene glycol monomethyl ether acetate, Triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, ethylene glycol monophenyl ether), amine (eg, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, Tylenediamine, diethylenetriamine, triethylenetetramine, polyethyleneimine, tetramethylpropylenediamine) and other polar solvents (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, dimethylsulfoxide, sulfolane, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-vinyl-2-pyrrolidone, 2-oxazolidone, 1,3-dimethyl-2-imidazolidinone, acetonitrile, acetone). In addition, a water-soluble organic solvent may be used independently and may use 2 or more types together.

(Other additives)
Other additives used in the present embodiment include, for example, drying inhibitors (wetting agents), anti-fading agents, emulsion stabilizers, penetration enhancers, ultraviolet absorbers, antiseptics, antifungal agents, and pH adjusters. And known additives such as surface tension modifiers, antifoaming agents, viscosity modifiers, dispersants, dispersion stabilizers, rust inhibitors, chelating agents and the like. In the case of water-soluble ink, these various additives are added directly to the ink. When an oil-soluble dye is used in the form of a dispersion, it is generally added to the dispersion after the preparation of the dye dispersion, but it may be added to the oil phase or the aqueous phase at the time of preparation.

  The ultraviolet absorber is used for the purpose of improving image storability. Examples of ultraviolet absorbers include benzotriazoles described in JP-A Nos. 58-185677, 61-190537, JP-A-2-782, JP-A-5-97075, JP-A-9-34057, and the like. Compounds, benzophenone compounds described in JP-A No. 46-2784, JP-A No. 5-194433, US Pat. No. 3,214,463, etc., JP-B Nos. 48-30492, 56-211141, Cinnamic acid compounds described in, for example, Kaihei 10-88106, JP-A-4-298503, 8-53427, 8-239368, 10-182621, JP-A-8- No. 501291, etc., triazine compounds, Research Disclosure No. The compounds described in No. 24239, compounds that emit fluorescence by absorbing ultraviolet rays typified by stilbene-based compounds and benzoxazole-based compounds, so-called fluorescent brighteners, can also be used.

The anti-fading agent is used for the purpose of improving image storage stability. As the antifading agent, various organic and metal complex antifading agents can be used. Organic anti-fading agents include hydroquinones, alkoxyphenols, dialkoxyphenols, phenols, anilines, amines, indanes, chromans, alkoxyanilines, heterocycles, etc. Complex, zinc complex and the like. More specifically, Research Disclosure No. No. 17643, Nos. VII to I, J; 151
62, the same No. No. 18716, page 650, left column, ibid. No. 36544, page 527, ibid. No. 307105, page 872, ibid. The compounds described in the patent cited in US Pat. No. 15,162, and the compounds included in the general formulas and compound examples of representative compounds described in JP-A-62-215272, pages 127 to 137 can be used.

  Examples of the antifungal agent include sodium dehydroacetate, sodium benzoate, sodium pyridinethione-1-oxide, p-hydroxybenzoic acid ethyl ester, 1,2-benzisothiazolin-3-one and salts thereof. These are preferably used in an amount of 0.02 to 1.00% by weight in the ink.

  As the pH adjuster, a neutralizer (organic base, inorganic alkali) can be used. For the purpose of improving the storage stability of the inkjet ink, the pH adjuster is preferably added so that the inkjet ink has a pH of 6 to 10, and more preferably added to have a pH of 7 to 10.

  Examples of the surface tension adjusting agent used in the present embodiment include nonionic surfactants, cationic surfactants, anionic surfactants, betaine surfactants, and the like.

  In addition, the addition amount of the surface tension adjusting agent is preferably an addition amount that adjusts the surface tension of the ink to 20 to 60 mN / m, and preferably an addition amount that is adjusted to 20 to 45 mN / m, in order to eject droplets well by inkjet. More preferable is an addition amount adjusted to 25 to 40 mN / m.

  Specific examples of surfactants include fatty acid salts, alkyl sulfate esters, alkylbenzene sulfonates, alkyl naphthalene sulfonates, dialkyl sulfosuccinates, alkyl phosphate esters, naphthalene sulfonate formalin condensation in hydrocarbons Products, anionic surfactants such as polyoxyethylene alkyl sulfates, polyoxyethylene alkyl ethers, polyoxyethylene alkyl allyl ethers, polyoxyethylene fatty acid esters, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, polyoxy Nonionic surfactants such as ethylene alkylamine, glycerin fatty acid ester and oxyethyleneoxypropylene block copolymer are preferred. Further, SURFYNOLS (Air Products & Chemicals), which is an acetylene-based polyoxyethylene oxide surfactant, is also preferably used. An amine oxide type amphoteric surfactant such as N, N-dimethyl-N-alkylamine oxide is also preferred.

  Further, pages (37) to (38) of JP-A-59-157636, Research Disclosure No. The surfactants described in 308119 (1989) can also be used.

  Also, fluorine (fluorinated alkyl) surfactants, silicone surfactants, and the like described in JP-A Nos. 2003-322926, 2004-325707, and 2004-309806 are disclosed. By using, the abrasion resistance can be improved.

  These surface tension modifiers can also be used as antifoaming agents, and fluorine compounds, silicone compounds, chelating agents represented by EDTA, and the like can also be used.

  Next, the treatment liquid brought into contact with the above-described ink will be described in detail.

[Treatment solution]
The treatment liquid used in the present embodiment is mainly used in a set with ink for the purpose of suppressing high-speed printing by suppressing ink bleeding.

  The treatment liquid used in the present embodiment is preferably a treatment liquid that generates aggregates by changing the pH of the ink. At this time, the pH of the treatment liquid is preferably 1 to 6, more preferably 2 to 5, and still more preferably 3 to 5. In addition, in order to make the treatment solution acidic, a compound having a furan, pyrrole, pyrroline, pyrrolidone, pyrone, pyrrole, thiophene, indole, pyridine, quinoline structure and further having a carboxyl group as a functional group, such as pyrrolidone carboxyl Acid, pyrone carboxylic acid, pyrrole carboxylic acid, furan carboxylic acid, pyridine carboxylic acid, coumaric acid, thiophene carboxylic acid, nicotinic acid, derivatives of these compounds, or salts thereof are added to the treatment liquid.

  Moreover, as said compound, it is preferable that they are pyrrolidone carboxylic acid, pyrone carboxylic acid, furan carboxylic acid, coumaric acid, or these compound derivatives, or these salts. In addition, these compounds may be used by 1 type and may be used together 2 or more types.

Moreover, it replaces with said compound and a coagulant | flocculant may be added to a process liquid. Examples of such a flocculant include alkali metal ions such as lithium ion, sodium ion and potassium ion, aluminum ion, barium ion, calcium ion, copper ion, iron ion, magnesium ion, manganese ion, nickel ion, tin ion and titanium. Ions, zinc ions and other polyvalent metal ions, hydrochloric acid, bromic acid, hydroiodic acid, sulfuric acid, nitric acid, phosphoric acid, thiocyanic acid, and acetic acid, succinic acid, lactic acid, fumaric acid, fumaric acid, citric acid, salicylic acid And organic carboxylic acids such as benzoic acid and salts of organic sulfonic acids.

  Further, the treatment liquid used in the present embodiment is not limited to the above-described liquid as long as the ink in which the color material (organic pigment or the like) is dissolved and / or dispersed is aggregated. Specific examples of the treatment liquid include a treatment liquid that aggregates by changing the pH of the ink (for example, a treatment liquid described in JP-A Nos. 7-1837 and 2004-359841), and an inorganic salt added to the ink. Treatment liquids to be agglomerated (for example, treatment liquids described in JP-A-5-202328, JP-A-5-208548, JP-A-9-29950), a compound having a charge opposite to that of a charged ink colorant, an anion, By changing the solvent composition of the ink (for example, the treatment liquid described in Japanese Patent No. 2667401, Japanese Patent No. 3466756, Japanese Patent Application Laid-Open No. 8-174997, Japanese Patent Application Laid-Open No. 2001-199151) that reacts with cations and aggregates. Examples of the treatment liquid include agglomeration.

  Further, the treatment liquid may contain other additives within a range that does not impair the effects of the present invention. Other additives include, for example, anti-drying agents (wetting agents), anti-fading agents, emulsion stabilizers, penetration enhancers, ultraviolet absorbers, preservatives, anti-fungal agents, pH adjusters, surface tension adjusters, Known additives such as foaming agents, viscosity modifiers, dispersants, dispersion stabilizers, rust preventives, chelating agents, and the like, specific examples of other additives (see item 5) included in the above-mentioned inks The ones shown in the examples are applicable. Moreover, the content of polymer fine particles in the entire ink set can be increased by containing the above-mentioned polymer fine particles in the treatment liquid.

[Inkjet recording system]
Hereinafter, a recording paper and a recording film used in the case of performing ink jet printing using the ink set according to the present invention will be described. The support in recording paper and recording film is made of chemical pulp such as LBKP and NBKP, mechanical pulp such as GP, PGW, RMP, TMP, CTMP, CMPMP, CGP, and waste paper pulp such as DIP. Additives such as known pigments, binders, sizing agents, fixing agents, cationic agents, paper strength enhancers, etc. can be mixed and manufactured using various devices such as long net paper machines and circular net paper machines. is there. In addition to these supports, either synthetic paper or plastic film sheet may be used, and the thickness of the support is preferably 10 to 250 μm and the basis weight is preferably 10 to 250 g / m 2. The support may be provided with an ink receiving layer and a backcoat layer as they are, or after a size press or anchor coat layer is provided with starch, polyvinyl alcohol or the like, an ink receiving layer and a backcoat layer may be provided. Further, the support may be flattened by a calendar device such as a machine calendar, a TG calendar, or a soft calendar. In the present embodiment, as the support, paper and plastic films that are laminated on both sides with polyolefin (for example, polyethylene, polystyrene, polyethylene terephthalate, polybutene, and copolymers thereof) are more preferably used. It is preferable to add a white pigment (for example, titanium oxide or zinc oxide) or a tinting dye (for example, cobalt blue, ultramarine blue, or neodymium oxide) to the polyolefin.

The ink receiving layer provided on the support contains a pigment and an aqueous binder. As the pigment, a white pigment is preferable, and as the white pigment, calcium carbonate, kaolin, talc, clay, diatomaceous earth, synthetic amorphous silica, aluminum silicate, magnesium silicate, calcium silicate, aluminum hydroxide, alumina, lithopone, zeolite, Examples thereof include white inorganic pigments such as barium sulfate, calcium sulfate, titanium dioxide, zinc sulfide and zinc carbonate, and organic pigments such as styrene pigments, acrylic pigments, urea resins and melamine resins. As the white pigment contained in the ink receiving layer, porous inorganic pigments are preferable, and synthetic amorphous silica having a large pore area is particularly preferable. As the synthetic amorphous silica, either anhydrous silicic acid obtained by a dry production method or hydrous silicic acid obtained by a wet production method can be used, but it is particularly desirable to use hydrous silicic acid.

  Examples of the aqueous binder contained in the ink receiving layer include water-soluble polyvinyl alcohol, silanol-modified polyvinyl alcohol, starch, cationized starch, casein, gelatin, carboxymethylcellulose, hydroxyethylcellulose, polyvinylpyrrolidone, polyalkylene oxide, polyalkylene oxide derivatives, and the like. Water-dispersible polymers such as water-soluble polymers, styrene butadiene latexes, and acrylic emulsions. These aqueous binders can be used alone or in combination of two or more. In the present embodiment, among these, polyvinyl alcohol and silanol-modified polyvinyl alcohol are particularly preferable in terms of adhesion to the pigment and resistance to peeling of the ink receiving layer. In addition to the pigment and the aqueous binder, the ink receiving layer can contain a mordant, a water resistance agent, a light resistance improver, a surfactant, and other additives.

  The mordant added to the ink receiving layer is preferably immobilized. For that purpose, a polymer mordant is preferably used. For the polymer mordant, JP-A-48-28325, 54-74430, 54-124726, 55-22766, 55-142339, 60-23850, 60-23835, 60-23852, 60-23853, 60-57836, 60-60643, 60-118834, 60-122940, 60-122941, 60-122942, 60- No. 235134, JP-A-1-161236, U.S. Pat.Nos. 2,484,430, 2,548,564, 3,148,061, 3,309,690, 4,115,124, 4,124,386, 4,193,800, 4,273,853, 4,282,305, It is described in each specification of the same No. 4450224. An image receiving material containing a polymer mordant described in JP-A-1-161236, pages 212 to 215 is particularly preferred. When the polymer mordant described in the publication is used, an image with excellent image quality is obtained and the light resistance of the image is improved.

  The water-proofing agent is effective for making the image water-resistant. As these water-proofing agents, cationic resins are particularly desirable. Examples of such cationic resins include polyamide polyamine epichlorohydrin, polyethyleneimine, polyamine sulfone, dimethyl diallyl ammonium chloride polymer, cationic polyacrylamide, colloidal silica, etc. Among these cationic resins, polyamide polyamine epichlorohydrin is particularly preferable. is there. The content of these cationic resins is preferably 1 to 15% by weight, particularly preferably 3 to 10% by weight, based on the total solid content of the ink receiving layer.

  Examples of the light resistance improver include zinc sulfate, zinc oxide, hindered amine-based antioxidants, benzophenone-based and benzotriazole-based ultraviolet absorbers, and the like. Of these, zinc sulfate is particularly preferred.

  The surfactant functions as a coating aid, a peelability improver, a slippage improver or an antistatic agent. The surfactant is described in JP-A Nos. 62-173463 and 62-183457. An organic fluoro compound may be used in place of the surfactant. The organic fluoro compound is preferably hydrophobic. Examples of the organic fluoro compound include a fluorine-based surfactant, an oily fluorine-based compound (for example, fluorine oil), and a solid fluorine compound resin (for example, tetrafluoroethylene resin). As for the organic fluoro compound, JP-B-57-9053 (columns 8 to 17), JP-A-61-2994, JP-A-62-135826, JP-A-2003-322926, JP-A-2004-325707, JP-A-2004-325707, There is description in each publication of 2004-309806. Examples of other additives added to the ink receiving layer include pigment dispersants, thickeners, antifoaming agents, dyes, fluorescent whitening agents, preservatives, pH adjusters, matting agents, and hardening agents. . The ink receiving layer may be one layer or two layers.

  Further, the recording paper and the recording film can be provided with a backcoat layer, and examples of components that can be added to this layer include a white pigment, an aqueous binder, and other components. Examples of white pigments contained in the backcoat layer include light calcium carbonate, heavy calcium carbonate, kaolin, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, and aluminum silicate. White inorganic pigments such as diatomaceous earth, calcium silicate, magnesium silicate, synthetic amorphous silica, colloidal silica, colloidal alumina, pseudoboehmite, aluminum hydroxide, alumina, lithopone, zeolite, hydrous halloysite, magnesium carbonate, magnesium hydroxide And organic pigments such as styrene plastic pigment, acrylic plastic pigment, polyethylene, microcapsule, urea resin and melamine resin.

  As the aqueous binder contained in the backcoat layer, styrene / maleate copolymer, styrene / acrylate copolymer, polyvinyl alcohol, silanol modified polyvinyl alcohol, starch, cationized starch, casein, gelatin, carboxymethylcellulose Water-soluble polymers such as hydroxyethyl cellulose and polyvinyl pyrrolidone, water-dispersible polymers such as styrene butadiene latex and acrylic emulsion, and the like. Examples of other components contained in the backcoat layer include an antifoaming agent, an antifoaming agent, a dye, a fluorescent brightening agent, a preservative, and a water-proofing agent.

  Polymer latex may be added to the constituent layers (including the backcoat layer) of the ink jet recording paper and recording film. The polymer latex is used for the purpose of improving film physical properties such as dimensional stabilization, curling prevention, adhesion prevention, and film cracking prevention. The polymer latex is described in JP-A Nos. 62-245258, 62-1316648, and 62-110066. When a polymer latex having a low glass transition temperature (40 ° C. or lower) is added to a layer containing a mordant, cracking and curling of the layer can be prevented. Also, curling can be prevented by adding a polymer latex having a high glass transition temperature to the backcoat layer.

  The ink and the ink set according to the present invention are not limited to the ink jet recording system, but use a publicly known system, for example, a charge control system that discharges ink using electrostatic attraction force, or a vibration pressure of a piezo element. A drop-on-demand method (pressure pulse method), an acoustic ink jet method that converts an electrical signal into an acoustic beam, irradiates the ink, and discharges the ink using radiation pressure, and heats the ink to form bubbles, resulting in It is used in thermal ink jet systems that utilize the pressure. Inkjet recording methods use a method of ejecting a large number of low-density inks called photo inks in a small volume, a method of improving image quality using a plurality of inks having substantially the same hue and different concentrations, and colorless and transparent inks. The method is included.

[Overall configuration of inkjet recording apparatus]
FIG. 1 is an overall configuration diagram of an ink jet recording apparatus as an embodiment of an image forming apparatus. As shown in the figure, an inkjet recording apparatus 10 includes a processing liquid head (corresponding to a processing liquid adhering means) 11 for discharging a processing liquid, black (K), cyan (C), magenta (M), A printing unit 12 having a plurality of print heads (corresponding to ink liquid ejecting means) 12K, 12C, 12M, and 12Y provided corresponding to each color for ejecting yellow (Y) ink, and for processing liquid A processing liquid storage / loading unit 13 for storing the processing liquid supplied to the head 11, an ink storage / loading unit 14 for storing color inks supplied to the print heads 12K, 12C, 12M, and 12Y, and printing A solvent absorbing roller (corresponding to a solvent absorbing means) 15 disposed downstream of the unit 12, a medium supply unit 18 for supplying the recording medium 16, a decurling unit 20 for removing the curl of the recording medium 16, and the above processing. An adsorption belt conveyance unit (corresponding to a conveyance unit) 22 that is arranged to face the nozzle surface (liquid ejection surface) of the liquid head 11 and the printing unit 12 and conveys the recording medium 16 while maintaining the flatness of the recording medium 16. And a discharge unit 26 for discharging the recorded recording medium 16 (printed material) to the outside.

  In FIG. 1, a roll paper (continuous paper) magazine 19 is shown as an example of the media supply unit 18 regarding the supply system of the recording medium 16, but a plurality of magazines having different paper widths, paper qualities, and the like may be provided side by side. Further, instead of the roll paper magazine or in combination therewith, the paper may be supplied by a cassette in which cut papers are stacked and loaded.

  When a plurality of types of recording media can be used, an information recording body such as a bar code or a wireless tag that records the recording medium type information is attached to the magazine, and the information on the information recording body is read by a predetermined reader. Thus, it is preferable to automatically determine the type of recording medium to be used (media type) and perform ejection control so as to realize ejection of an appropriate processing liquid and ink according to the media type.

  The recording medium 16 delivered from the media supply unit 18 retains curl due to having been loaded in the magazine 19. In order to remove this curl, heat is applied to the recording medium 16 by the heating drum 30 in the direction opposite to the curl direction of the magazine in the decurling unit 20. At this time, it is more preferable to control the heating temperature so that the printed surface is slightly curled outward.

  In the case of an apparatus configuration that uses roll paper, a cutter (first cutter) 28 is provided as shown in FIG. 1, and the roll paper is cut into a desired size by the cutter 28. Note that the cutter 28 is not necessary when cut paper is used.

  After the decurling process, the cut recording medium 16 is sent to the suction belt conveyance unit 22. The suction belt conveyance unit 22 has a structure in which an endless belt 33 is wound between rollers 31 and 32, and at least a portion facing the nozzle surface of the printing unit 12 forms a horizontal surface (flat surface). Has been.

  The belt 33 has a width that is wider than the width of the recording medium 16, and a plurality of suction holes (not shown) are formed on the belt surface. An adsorption chamber 34 is provided inside the belt 33 spanned between the rollers 31 and 32 at a position facing the nozzle surface of the printing unit 12, and the adsorption chamber 34 is sucked by a fan 35 to be negative pressure. As a result, the recording medium 16 is sucked and held on the belt 33.

  When the power of the motor (reference numeral 88 in FIG. 7) is transmitted to at least one of the rollers 31 and 32 around which the belt 33 is wound, the belt 33 is driven in the counterclockwise direction in FIG. The recording medium 16 held in is conveyed from the right to the left in FIG.

  Although a mode using a roller / nip conveyance mechanism instead of the suction belt conveyance unit 22 is also conceivable, if the roller / nip conveyance is performed in the printing area, the roller comes into contact with the printing surface of the paper immediately after printing, so that the image blurs. There is a problem that it is easy. Therefore, as in this example, suction belt conveyance that does not bring the image surface into contact with each other in the print region is preferable. The suction method is not limited to the suction suction (vacuum suction) described above, and may be based on electrostatic suction.

Since ink adheres to the belt 33 when a borderless print or the like is printed, the belt cleaning unit 36 is provided at a predetermined position outside the belt 33 (an appropriate position other than the print area). Although details of the configuration of the belt cleaning unit 36 are not shown, for example, there are a method of niping a brush roll, a water absorbing roll, etc., an air blow method of blowing clean air, or a combination thereof. In the case where the cleaning roll is nipped, the cleaning effect is great if the belt linear velocity and the roller linear velocity are changed.

  The treatment liquid head 11 and the print heads 12K, 12C, 12M, and 12Y have lengths corresponding to the maximum paper width of the recording medium 16 targeted by the inkjet recording apparatus 10 (see FIG. 2). Is a full-line head in which nozzles for ejecting ink or nozzles for ejecting treatment liquid are arranged over a length (full width of the drawable range) exceeding at least one side of the maximum size recording medium.

  As shown in FIG. 1, the print heads 12K, 12C, 12M, and 12Y are black (K), cyan (C), magenta (M), and yellow (Y) from the upstream side along the feeding direction of the recording medium 16. The processing liquid head 11 is arranged further upstream of the printing unit 12. Each of the heads 11, 12 K, 12 C, 12 M, and 12 Y is fixedly installed so as to extend along a direction substantially orthogonal to the conveyance direction of the recording medium 16.

  With such a head arrangement, the treatment liquid can be attached to the recording surface (printed surface) of the recording medium 16 by the treatment liquid head 11 before the ink of each color is ejected by the printing unit 12. The recording medium 16 is ejected from the print heads 12K, 12C, 12M, and 12Y toward the recording medium 16 to which the processing liquid is adhered while the recording medium 16 is conveyed by the suction belt conveyance unit 22. A color image can be formed thereon. At this time, the treatment liquid previously deposited on the recording medium 16 and the ink subsequently deposited on the recording medium 16 react on the recording medium 16 to generate aggregates.

  As described above, according to the configuration in which the full line type processing liquid head 11 and the print heads 12K, 12C, 12M, and 12Y having nozzle rows covering the entire width of the paper are provided, recording is performed in the paper feeding direction (sub-scanning direction). An image can be recorded on the entire surface of the recording medium 16 by performing the operation of relatively moving the medium 16 and the printing unit 12 once (that is, by one sub-scan). Thereby, it is possible to perform high-speed printing as compared with a shuttle type head in which the recording head reciprocates in a direction orthogonal to the paper transport direction, and productivity can be improved.

  In the present embodiment, the configuration of KCMY standard colors (four colors) is exemplified, but the combination of ink colors and the number of colors is not limited to this, and light ink, dark ink, and special color ink are used as necessary. May be added. For example, it is possible to add a print head that discharges light ink such as light cyan and light magenta. Also, the arrangement order of the color heads is not particularly limited.

  The processing liquid storage / loading unit 13 includes a processing liquid tank that stores the processing liquid, and the tank is communicated with the processing liquid head 11 via an appropriate pipe line. The processing liquid supplied from the processing liquid tank is discharged as droplets from the processing liquid head 11. The processing liquid storage / loading unit 13 includes notification means (display means, warning sound generation means) for notifying when the remaining amount of processing liquid is low.

  The ink storage / loading unit 14 includes ink tanks 14K, 14C, 14M, and 14Y that store inks of colors corresponding to the print heads 12K, 12C, 12M, and 12Y. The print heads 12K, 12C, 12M, and 12Y communicate with each other. Further, the ink storage / loading unit 14 includes notifying means (display means, warning sound generating means) for notifying when the ink remaining amount is low, and has a mechanism for preventing erroneous loading between colors. ing.

  The surface of the solvent absorbing roller 15 is composed of a porous member 15A, and has a length corresponding to the maximum width of the recording medium 16 targeted by the inkjet recording apparatus 10. The rotation shaft 15B of the solvent absorbing roller 15 is disposed along a direction (main scanning direction) orthogonal to the conveyance direction of the recording medium 16. The solvent absorbing roller 15 supported rotatably about the rotation shaft 15B can rotate so that the relative speed with respect to the recording medium 16 becomes 0 in accordance with the conveyance speed of the recording medium 16. This prevents image distortion caused by rubbing.

  The solvent absorbing roller 15 may have a length corresponding to the entire width of the recording medium 16 by one (single) long roller member, or a direction substantially orthogonal to the conveyance direction of the recording medium 16. It may be divided into a plurality of roller modules along the (main scanning direction), and these may be arranged to achieve a required length. A configuration in which a plurality of rows of solvent absorbing rollers are arranged along the conveyance direction of the recording medium 16 is also possible.

  Although not shown in FIG. 1, a vertical mechanism for moving the solvent absorbing roller 15 up and down with respect to the recording medium 16 is provided. The contact pressure with the recording medium 16 is controlled by controlling the vertical mechanism according to a command from a system control system to be described later and adjusting the position of the solvent absorbing roller 15 (relative position in the direction perpendicular to the recording surface of the recording medium 16). In addition, the clearance with the recording medium 16 can be varied. In the case of a configuration having a plurality of roller modules, it is preferable to provide a mechanism for controlling the vertical position of each roller module.

  By moving the recording medium 16 in the transport direction while bringing the solvent absorbing roller 15 into contact with the ink on the recording medium 16, the solvent on the recording medium 16 (solvent separated from the color material) is generated by the capillary force of the porous member 15A. ) Is absorbed by the solvent absorbing roller 15. In this way, the ink from which excess solvent has been removed by the solvent absorbing roller 15 increases the bonding force between the coloring materials, and is fixed to the recording medium 16.

  In the present embodiment, the solvent absorbing roller 15 composed of the porous member 15A is used as the means for absorbing and removing the solvent. However, the shape of the solvent absorbing means is not limited to the roller shape, but is a belt shape. It may be.

  A heating unit 17 is provided on the downstream side of the solvent absorbing roller 15 that absorbs and removes the main solvent. The heating unit 17 directly applies hot air heated to a predetermined temperature of about 30 ° C. or more to the recording medium 16 to further evaporate the residual solvent in the aggregate on the recording medium 16. Thereby, the polymer fine particles in the aggregate are dry-cured. Accordingly, the color material is fixed in a film form on the recording medium 16, and printing excellent in abrasion resistance, water resistance, and fixability can be performed.

  In this embodiment, an example in which the color material is fixed by a method in which hot air is directly applied to the aggregate on the recording medium 16 is shown as a heating method of the aggregate. However, the present invention is not limited to this. For example, a method of applying heat with a heater may be used. In addition, the arrangement of the heating unit 17 is on the downstream side of the solvent absorbing roller 15 in the present embodiment. However, the heating unit 17 is not limited to this, and the solvent absorbing roller 15 can be heated as long as it can be heated after the aggregate is generated. It may be arranged on the upstream side.

  Thus, the generated printed matter (result obtained by printing) is discharged from the discharge unit 26. It is preferable that the original image to be printed (printed target image) and the test print are discharged separately. The ink jet recording apparatus 10 is provided with a sorting means (not shown) for switching the paper discharge path in order to select the print product of the main image and the print product of the test print and send them to the discharge units 26A and 26B. Yes.

  Note that when the main image and the test print are simultaneously formed in parallel on a large sheet, the test print portion is separated by the cutter (second cutter) 38. The cutter 38 is provided immediately before the discharge unit 26, and cuts the main image and the test print unit when the test print is performed on the image margin.

[Print head structure]
Next, the structure of the print head will be described. Since the structure of the print heads 12K, 12C, 12M, and 12Y for each color is the same, the print head is represented by the reference numeral 50 in the following.

  FIG. 2A is a plan perspective view showing a structural example of the print head 50, and FIG. 2B is an enlarged view of a part thereof. 3 is a plan perspective view showing another example of the structure of the print head 50, and FIG. 4 is a cross-sectional view showing a three-dimensional configuration of one droplet discharge element (an ink chamber unit corresponding to one nozzle 51). 4 is a sectional view taken along line 4-4 in FIG.

  In order to increase the dot pitch printed on the recording medium 16, it is necessary to increase the nozzle pitch in the print head 50. As shown in FIGS. 2A and 2B, the print head 50 of this example includes an ink chamber unit (a nozzle 51, which is an ink droplet ejection port, and a pressure chamber 52 corresponding to each nozzle 51. It has a structure in which the droplet discharge elements 53 are arranged in a zigzag matrix (two-dimensionally), and is thereby projected so as to be aligned along the head longitudinal direction (direction perpendicular to the paper feed direction). High density of substantial nozzle interval (projection nozzle pitch) is achieved.

A configuration in which nozzle rows having a length corresponding to the full width Wm of the recording medium 16 are configured in a direction (arrow M direction; main scanning direction) substantially orthogonal to the feeding direction (arrow S direction; sub-scanning direction) of the recording medium 16 is as follows. It is not limited to this example. For example, instead of the configuration shown in FIG. 2A, as shown in FIG. 3, a short head module 50 ′ in which a plurality of nozzles 51 are two-dimensionally arranged is arranged in a staggered manner and connected to form a recording medium. It is preferable to configure a line head having a nozzle row having a length corresponding to the full width of 16. This is because a line head enables high-speed printing.

  The pressure chamber 52 provided corresponding to each nozzle 51 has a substantially square planar shape (see FIGS. 2A and 2B), and is connected to the nozzle 51 at both diagonal corners. An outlet and an inlet (supply port) 54 for supply ink are provided. The shape of the pressure chamber 52 is not limited to this example, and the planar shape may have various forms such as a quadrangle (rhombus, rectangle, etc.), a pentagon, a hexagon, other polygons, a circle, and an ellipse.

  As shown in FIG. 4, each pressure chamber 52 communicates with a common flow channel 55 through a supply port 54. The common channel 55 communicates with an ink tank (not shown in FIG. 4, not shown in FIG. 6 and indicated by reference numeral 60) serving as an ink supply source, and the ink supplied from the ink tank 60 passes through the common channel 55 in FIG. Then, it is distributed and supplied to each pressure chamber 52.

  An actuator 58 having an individual electrode 57 is joined to a pressure plate (vibrating plate also serving as a common electrode) 56 constituting a part of the pressure chamber 52 (the top surface in FIG. 4). By applying a drive voltage between the individual electrode 57 and the common electrode, the actuator 58 is deformed and the volume of the pressure chamber 52 is changed, and ink is ejected from the nozzle 51 due to the pressure change accompanying this. The actuator 58 is preferably a piezoelectric element using a piezoelectric material such as lead zirconate titanate or barium titanate. After the ink is ejected, when the displacement of the actuator 58 is restored, new ink is supplied from the common channel 55 through the supply port 54 to the pressure chamber 52.

  As shown in FIG. 5, the ink chamber unit 53 having such a structure is latticed in a fixed arrangement pattern along a row direction along the main scanning direction and an oblique column direction having a constant angle θ not orthogonal to the main scanning direction. The high-density nozzle head of this example is realized by arranging a large number in the shape.

  That is, with a structure in which a plurality of ink chamber units 53 are arranged at a constant pitch d along a certain angle θ with respect to the main scanning direction, the pitch P of the nozzles projected so as to be aligned in the main scanning direction is d × cos θ Thus, in the main scanning direction, each nozzle 51 can be handled equivalently as a linear arrangement with a constant pitch P. With such a configuration, a high-density nozzle array can be realized.

  When the nozzles are driven by a full line head having a nozzle row having a length corresponding to the entire printable width, (1) all the nozzles are driven simultaneously, (2) the nozzles are sequentially moved from one side to the other. (3) The nozzles are divided into blocks, and the nozzles are sequentially driven from one side to the other for each block, etc., and one line (1 in the width direction of the paper (direction perpendicular to the paper conveyance direction)) Driving a nozzle that prints a line of dots in a row or a line consisting of dots in a plurality of rows is defined as main scanning.

  In particular, when driving the nozzles 51 arranged in a matrix as shown in FIG. 5, the main scanning as described in (3) above is preferable. That is, nozzles 51-11, 51-12, 51-13, 51-14, 51-15, 51-16 are made into one block (other nozzles 51-21,..., 51-26 are made into one block, The nozzles 51-31,..., 51-36 as one block,...), And the nozzles 51-11, 51-12,. One line is printed in 16 width directions.

  On the other hand, by relatively moving the above-mentioned full line head and the paper, printing of one line (a line formed by one line of dots or a line composed of a plurality of lines) formed by the above-described main scanning is repeatedly performed. This is defined as sub-scanning.

  The direction indicated by one line (or the longitudinal direction of the belt-like region) recorded by the main scanning is referred to as a main scanning direction, and the direction in which the sub scanning is performed is referred to as a sub scanning direction. That is, in the present embodiment, the conveyance direction of the recording medium 16 is the sub-scanning direction, and the direction orthogonal to the recording medium 16 is the main scanning direction.

  In implementing the present invention, the nozzle arrangement structure is not limited to the illustrated example. In the present embodiment, a method of ejecting ink droplets by deformation of an actuator 58 typified by a piezo element (piezoelectric element) is adopted. However, in the practice of the present invention, the method of ejecting ink is not particularly limited. Instead of the piezo jet method, various methods such as a thermal jet method in which ink is heated by a heating element such as a heater to generate bubbles and ink droplets are ejected by the pressure can be applied.

  The structure of the treatment liquid head 11 is substantially the same as that of the print head 50 described above, although not shown. However, since the treatment liquid has only to be deposited substantially uniformly (substantially uniformly) on the area where the ink is ejected on the recording medium 16, formation of high density dots is not required as compared with the ink. Therefore, the treatment liquid head 11 can be configured to have a smaller number of nozzles (lower nozzle density) than the ink ejection head 50. Further, a configuration in which the nozzle diameter of the treatment liquid head 11 is larger than the nozzle diameter of the print head 50 for discharging ink is also possible.

[Configuration of ink supply system]
FIG. 6 is a schematic diagram showing the configuration of the ink supply system in the inkjet recording apparatus 10. The ink tank 60 is a base tank that supplies ink to the print head 50 and is installed in the ink storage / loading unit 14 described with reference to FIG. That is, the ink tank 60 in FIG. 6 is equivalent to the ink storage / loading unit 14 in FIG. In the form of the ink tank 60, there are a system that replenishes ink from a replenishing port (not shown) and a cartridge system that replaces the entire tank when the remaining amount of ink is low. A cartridge system is suitable for changing the ink type according to the intended use. In this case, it is preferable that the ink type information is identified by a barcode or the like, and ejection control is performed according to the ink type.

  As shown in FIG. 6, a filter 62 is provided between the ink tank 60 and the print head 50 in order to remove foreign substances and bubbles. The filter mesh size is preferably equal to or smaller than the nozzle diameter. Although not shown in FIG. 6, a configuration in which a sub tank is provided in the vicinity of the print head 50 or integrally with the print head 50 is also preferable. The sub-tank has a function of improving a damper effect and refill that prevents fluctuations in the internal pressure of the head.

  Further, the inkjet recording apparatus 10 is provided with a cap 64 as a means for preventing the nozzle 51 from drying or preventing an increase in ink viscosity near the nozzle, and a cleaning blade 66 as a means for cleaning the nozzle surface 50A. . A maintenance unit (recovery means) including the cap 64 and the cleaning blade 66 can be moved relative to the print head 50 by a moving mechanism (not shown), and maintenance is performed below the print head 50 from a predetermined retraction position as necessary. Moved to position.

  The cap 64 is displaced up and down relatively with respect to the print head 50 by an elevator mechanism (not shown). The cap surface 64A is covered with the cap 64 by raising the cap 64 to a predetermined raised position when the power is turned off or during printing standby, and bringing the cap 64 into close contact with the print head 50.

  The cleaning blade 66 is made of an elastic member such as rubber, and can slide on the nozzle surface 50A (nozzle plate surface) of the print head 50 by a blade moving mechanism (not shown). When ink droplets or foreign matter adheres to the nozzle plate surface, the nozzle plate surface is wiped by sliding the cleaning blade 66 on the nozzle plate.

  During printing or standby, when a specific nozzle is used less frequently and the ink viscosity in the vicinity of the nozzle increases, preliminary ejection is performed toward the cap 64 (also used as an ink receiver) to discharge the deteriorated ink. .

  If the print head 50 is not ejected for a certain period of time, the ink solvent near the nozzle evaporates and the viscosity of the ink near the nozzle increases. Ink cannot be ejected. Therefore, before this state is reached (within the range of viscosity at which ink can be discharged by the operation of the actuator 58), the actuator 58 is operated toward the ink receiver to discharge ink near the nozzle whose viscosity has increased. "Preliminary discharge" is performed. In addition, after the dirt on the surface of the nozzle plate is cleaned by a wiper such as a cleaning blade 66 provided as a cleaning means for the nozzle surface 50A, the foreign matter is prevented from entering the nozzle 51 by the wiper rubbing operation. Also, preliminary discharge is performed. Note that the preliminary discharge may be referred to as “empty discharge”, “purge”, “spitting”, or the like.

  On the other hand, if bubbles are mixed into the nozzle 51 or the pressure chamber 52 or if the viscosity of the ink in the nozzle 51 rises above a certain level, ink cannot be ejected by the preliminary ejection. In such a case, a cap 64 serving as a suction means is brought into contact with the nozzle surface 50A of the print head 50, and ink (ink mixed with bubbles or thickened ink) in the pressure chamber 52 is sucked by the suction pump 67. Ink removed by the suction operation is sent to the collection tank 68. The ink collected in the collection tank 68 may be reused, or may be discarded if it cannot be reused.

Since the above suction operation is performed on the entire ink in the pressure chamber 52, the amount of ink consumption is large. Therefore, when the increase in viscosity is small, it is preferable to perform preliminary discharge as much as possible. Note that the above-described suction operation is also performed when ink is initially loaded into the print head 50 or when use is started after a long stop.

  Although not shown, the processing liquid supply system is substantially the same as the ink supply system described with reference to FIG.

[Explanation of control system]
FIG. 7 is a principal block diagram showing the system configuration of the inkjet recording apparatus 10. The ink jet recording apparatus 10 includes a communication interface 70, a system controller 72, an image memory 74, a ROM 75, a motor driver 76, a heater driver 78, a solvent absorption roller driving unit 79, a print control unit 80, an image buffer memory 82, and a processing liquid head driver. 83, an ink head driver 84, and the like.

  The communication interface 70 is an interface unit that receives image data sent from the host computer 86. As the communication interface 70, a serial interface such as USB, IEEE 1394, Ethernet, and wireless network, or a parallel interface such as Centronics can be applied. In this part, a buffer memory (not shown) for speeding up communication may be mounted.

  Image data sent from the host computer 86 is taken into the inkjet recording apparatus 10 via the communication interface 70 and temporarily stored in the image memory 74. The image memory 74 is a storage unit that temporarily stores an image input via the communication interface 70, and data is read and written through the system controller 72. The image memory 74 is not limited to a memory made of a semiconductor element, and a magnetic medium such as a hard disk may be used.

  The system controller 72 includes a central processing unit (CPU) and its peripheral circuits, and functions as a control device that controls the entire inkjet recording apparatus 10 according to a predetermined program, and also functions as an arithmetic device that performs various calculations. . That is, the system controller 72 controls each part such as the communication interface 70, the image memory 74, the motor driver 76, the heater driver 78, etc., performs communication control with the host computer 86, read / write control of the image memory 74, and the like. A control signal for controlling the motor 88 and the heater 89 of the transport system is generated.

  The ROM 75 stores programs executed by the CPU of the system controller 72 and various data necessary for control. The ROM 75 may be a non-rewritable storage unit, or may be a rewritable storage unit such as an EEPROM. The image memory 74 is used as a temporary storage area for image data, and is also used as a program development area and a calculation work area for the CPU.

  The motor driver 76 is a driver (drive circuit) that drives the motor 88 in accordance with an instruction from the system controller 72. The heater driver 78 is a driver that drives the heater 89 such as the drying unit and the heating unit 17 in accordance with an instruction from the system controller 72.

  The print control unit 80 has a signal processing function for performing various processing and correction processing for generating a print control signal from the image data in the image memory 74 according to the control of the system controller 72, and the generated print The controller supplies data (dot data) to the processing liquid head driver 83 and the ink head driver 84.

  The print control unit 80 includes an image buffer memory 82, and image data, parameters, and other data are temporarily stored in the image buffer memory 82 when image data is processed in the print control unit 80. In FIG. 7, the image buffer memory 82 is shown in a mode associated with the print control unit 80, but it can also be used as the image memory 74. Also possible is an aspect in which the print controller 80 and the system controller 72 are integrated and configured with one processor.

  An overview of the flow of processing from image input to print output is as follows. Image data to be printed is input from the outside via the communication interface 70 and stored in the image memory 74. At this stage, for example, RGB image data is stored in the image memory 74.

In the inkjet recording apparatus 10, a pseudo continuous tone image is formed by changing the droplet ejection density and dot size of fine dots by ink (coloring material) to the human eye. It is necessary to convert to a dot pattern that reproduces the gradation (shading of the image) as faithfully as possible. Therefore, the original image (RGB) data stored in the image memory 74 is sent to the print control unit 80 via the system controller 72, and the print control unit 80 uses a halftoning technique such as a dither method or an error diffusion method. Is converted into dot data for each ink color.

  That is, the print control unit 80 performs processing for converting the input RGB image data into dot data of four colors K, C, M, and Y. Further, the print controller 80 discriminates the treatment liquid droplet ejection area (the area on the recording surface where the treatment liquid droplet ejection is necessary) based on the dot data of each color, and generates the treatment liquid droplet ejection dot data. . In this way, the dot data (for the treatment liquid and for each color) generated by the print control unit 80 is stored in the image buffer memory 82.

  The processing liquid head driver 83 generates a driving control signal for the processing liquid head 11 based on the processing liquid droplet ejection dot data stored in the image buffer memory 82. When the drive control signal generated by the processing liquid head driver 83 is applied to the processing liquid head 11, the processing liquid is discharged from the processing liquid head 11.

  Similarly, the ink head driver 84 generates a drive control signal for the print head 50 based on the ink ejection dot data stored in the image buffer memory 82. The drive control signal generated by the ink head driver 84 is applied to the print head 50, whereby ink is ejected from the print head 50. The processing liquid head driver 83 and the ink head driver 84 may each include a feedback control system for keeping the head driving conditions constant.

  An image is formed on the recording medium 16 by controlling the discharge of the processing liquid from the processing liquid head 11 and the discharge of the ink from the print head 50 in synchronization with the conveyance speed of the recording medium 16.

  As described above, based on the dot data generated through the required signal processing in the print control unit 80, the ejection amount and ejection of droplets from each nozzle via the processing liquid head driver 83 and the ink head driver 84. Timing control is performed. Thereby, a desired dot size and dot arrangement are realized.

The ink jet recording apparatus 10 of this example further includes an ink information reading unit 90, a treatment liquid information reading unit 92, and a media type detection unit 94. The ink information reading unit 90 is a means for acquiring ink type information. Specifically, for example, ink identification information and physical properties from the shape of the cartridge of the ink tank 60 (see FIG. 6) (a specific shape that can identify the ink type), or a barcode or IC chip incorporated in the cartridge. Means for reading information can be used. In addition, the operator may input necessary information using a user interface.

  Similarly, the processing liquid information reading unit 92 is means for acquiring information related to the type of processing liquid. Specifically, for example, a means for reading processing liquid identification information and physical property information from the shape of the cartridge of the processing liquid tank (a specific shape capable of identifying the liquid type) or a barcode or IC chip incorporated in the cartridge Can be used. In addition, the operator may input necessary information using a user interface.

  The media type detection unit 94 is means for detecting the type (paper type) and size of the recording medium. For example, a means for reading information such as a barcode attached to the magazine 19 of the media supply unit 18 (identification information, media type information, etc.), a sensor (media width detection sensor, A sensor for detecting the thickness of the medium, a sensor for detecting the reflectance of the medium, and the like are used, and an appropriate combination thereof is also possible. Further, in place of or in combination with these automatic detection means, it is possible to specify information such as paper type and size by input from a predetermined user interface.

  Information obtained from each means of the ink information reading unit 90, the processing liquid information reading unit 92, and the media type detection unit 94 is sent to the system controller 72, and discharge control of the processing liquid and ink (control of discharge amount and discharge timing). For example, appropriate droplet ejection according to the conditions is executed. That is, the system controller 72 determines the permeation speed characteristic of the recording medium 16 based on the information obtained from each means of the ink information reading unit 90, the processing liquid information reading unit 92, and the media type detection unit 94, and the processing liquid Whether or not to use is used, and when the treatment liquid is used, the discharge amount is controlled.

  For example, the ink jet recording apparatus 10 includes information storage means (for example, the ROM 75 shown in FIG. The system controller 72 refers to the media type table to determine the penetration speed characteristic of the recording medium 16 to be used.

  As a means for grasping the permeation speed characteristic of the recording medium 16, the medium ID (identification information) is acquired from the media type detection unit 94 and the permeation speed characteristic of the medium is grasped by referring to the media type table. Alternatively, information indicating the penetration rate characteristic of the medium may be recorded in an information recording medium such as a barcode attached to the magazine, and the information on the penetration rate characteristic of the medium may be read directly from the media type detection unit 94.

  Alternatively, it is possible to use means for actually measuring the permeation speed of the recording medium 16. For example, ink or treatment liquid or both of them are ejected onto the recording medium 16, and the state of dots formed by the test droplets is read by a detection means (not shown) such as an image sensor, and the obtained information is obtained. Based on this, the penetration rate can be calculated.

As described with reference to FIG. 1, the inkjet recording apparatus 10 of the present example includes a processing liquid head 11 upstream of the printing unit 12, and the preceding (upstream) processing liquid is used before ink is ejected by the printing unit 12. The head 11 is configured to previously apply the treatment liquid to the printing surface of the recording medium 16 only once. In the case of such a configuration, the amount of processing liquid on the recording medium 16 gradually decreases as the amount of ink ejected by the printing unit 12 increases, so that the processing on the recording medium 16 proceeds toward the downstream side of the printing unit 12. The amount of liquid decreases. The treatment liquid needs to remain in the vicinity of the surface of the recording medium 16 until the droplet ejection by the final stage (the most downstream) print head (the yellow head 12Y in FIG. 1) in the print unit 12 is completed. In addition, the amount of ejected treatment liquid by the treatment liquid head 11 is determined based on the type of the recording medium 16, the physical properties of the treatment liquid, the ink ejection amount, the conveyance speed of the recording medium 16, and the like. Is done.

  Further, the system controller 72 shown in FIG. 7 controls the solvent absorption roller driving unit 79 in accordance with the thickness of the recording medium 16 and the penetration speed characteristic, and the vertical position of the solvent absorption roller 15 (the contact with the recording medium 16). The contact pressure or the clearance amount with the recording medium 16) and the rotation speed are appropriately controlled. The solvent absorbing roller driving unit 79 is a means for adjusting the position and rotational speed of the solvent absorbing roller 15 with respect to the recording surface of the recording medium 16. The solvent absorbing roller driving unit 79 moves the solvent absorbing roller 15 up and down and the mechanism electrically. A motor (actuator) and driver which are power sources for driving, a power transmission mechanism (such as a belt, pulley or gear, or an appropriate combination thereof) for transmitting the driving force of the motor to the vertical mechanism, and the solvent absorbing roller 15 are rotated. And a motor and driver that serve as a power source for power generation, a power transmission mechanism, a heater driver of the heating unit 17 that heats and drys the aggregate generated on the recording medium 16, and the like.

[Description of image forming process]
Next, an image forming process in the inkjet recording apparatus 10 of this example will be described. FIG. 8 is an enlarged view schematically showing a main part configuration around the printing unit 12 of the inkjet recording apparatus 10. In the figure, for the sake of simplicity, only one ink head (print head 50) is drawn after the treatment liquid head 11, but the actual printing unit 12 is as described in FIG. In addition, print heads 12K, 12C, 12M, and 12Y are provided for each of the four colors.

  In FIG. 8, the recording medium 16 is conveyed from right to left. The image forming process is as follows.

  (Step 1) The processing liquid 110 is ejected as droplets from the processing liquid head 11 arranged upstream in the recording medium conveyance direction (arrow A direction in FIG. 8), and the processing liquid 110 is previously applied to the recording surface 16A of the recording medium 16. Keep it attached.

  (Step 2) The ink 120 is ejected as droplets from the print head 50 disposed downstream of the processing liquid head 11, and the ink on the recording medium 16 is in a state where the liquid component of the processing liquid 110 remains on the surface. 120 is landed.

  (Step 3) By mixing the treatment liquid 110 and the ink 120 on the surface of the recording medium 16, the anionic group in the low molecular weight dispersant dispersed together with the coloring material in the ink 120 is mixed with the treatment liquid 110. In response to the change in pH due to contact with the water, agglutination occurs. Thereby, the color material in the ink 120 aggregates and the color material aggregate 126 is produced | generated.

  (Step 4) Then, as shown in FIG. 8, the color material aggregate 126 settles to the recording medium 16 side (downward). Thus, the droplets (dots) 130 of the ink 120 on the recording medium 16 are separated into the color material layer 132 composed of the settled color material aggregate 126 and the solvent 134 layer.

(Step 5) As the recording medium 16 is transported (transported in the direction of arrow A in FIG. 8), the droplets 130 separated into the color material layer 132 and the solvent 134 are moved to the position of the solvent absorbing roller 15. When the solvent 134 of the droplet 130 comes into contact with the solvent absorbing roller 15, the solvent 134 is absorbed by the solvent absorbing roller 15 by the capillary force of the porous member 15 </ b> A. The solvent absorbing roller 15 rotates in the direction of arrow B in FIG. 8 so that the relative speed with respect to the recording medium 16 becomes 0 in accordance with the conveyance speed of the recording medium 16, thereby preventing image disturbance due to ink rubbing. . At this time, since the polymer film 124 is formed around each dot 130, the movement of the color material on the surface of the recording medium 16 is suppressed, and the adhesion of the color material to the solvent absorbing roller 15 is also suppressed. Therefore, the image is not disturbed. That is, since the film 124 exists between the dots even when the solvent absorbing roller 15 absorbs the solvent, the film 124 plays a role of suppressing the movement of the ink and preventing the disturbance of the image when the solvent absorbing roller 15 contacts the ink. .

  The time from when the ink 120 ejected from the print head 50 lands (that is, when the two liquids are mixed) to when the solvent 134 comes into contact with the solvent absorbing roller 15 is the separation of the color material / solvent due to the two-liquid reaction. The positional relationship (distance L from the landing position to the solvent contact position) between the print head 50 and the solvent absorbing roller 15 and the conveyance speed of the recording medium 16 are set so as to be longer than the time until completion.

  (Step 6) In this way, the ink from which the solvent is removed by the solvent absorbing roller 15 (reference numeral 138 in FIG. 8) increases the bonding force between the coloring materials, and is fixed to the recording medium 16. As a result, the occurrence of bleeding can be prevented, and effects such as prevention of intercolor bleeding, acceleration of drying and fixing, and prevention of cockling can be obtained.

  (Step 7) Thereafter, hot air heated to about 30 ° C. by the heating unit 17 is applied to the recording medium 16, and the solvent component contained in the color material aggregate 126 is further evaporated and dried. Then, the polymer fine particles dispersed together with the color material are dried and cured to form a film, and the color material is firmly fixed on the recording medium 16 (reference numeral 139). Moreover, since the polymer fine particles are hydrophobic, the water resistance is also improved. As a result, a print having excellent abrasion resistance, water resistance, and fixability is formed.

  EXAMPLES Next, although an Example demonstrates this invention further in detail, this invention is not limited to a following example.

[Preparation of ink and treatment liquid]
(1-1) Preparation of Magenta Ink M-10 First, 10.0 g of Chromatic Jet Magenta DMQ (PR-122) manufactured by Ciba Specialty Chemicals, 1.0 g of low molecular weight dispersant 2-1 (molecular weight 339.5) Then, 4.0 g of glycerin and 35.0 g of ion-exchanged water were mixed with stirring to prepare a dispersion. Next, using an ultrasonic irradiation device (Vibra-cell VC-750 manufactured by SONICS, taper microchip: φ5 mm, Amplitude: 30%), the above dispersion is intermittently irradiated with ultrasonic waves (irradiation 0.5 s / pause). 1.0 s) for 2 hours to further disperse the pigment to obtain a 20% by mass pigment dispersion.

Separately from this, the following compound was weighed and mixed to prepare a mixed solution I.
・ Glycerin: 5.0g
・ Diethylene glycol: 10.0g
・ Orphine E1010 (manufactured by Nissin Chemical Industry): 1.0 g
・ Ion exchange water: 11.0g
The mixture I was slowly added dropwise to 23.0 g of a stirred 44% SBR dispersion (polymer fine particles: 3% by mass of acrylic acid, Tg 30 ° C.), and stirred and mixed to prepare a mixture II. Further, this mixed liquid II was stirred and mixed while slowly dropping into the above-mentioned 20% pigment dispersion to prepare 100 g of magenta ink M-2 (Example 1). Moreover, it prepared by the same method except having changed the low molecular dispersing agent of the magenta ink M-10 from the compound 2-1 to the compound 4 (N-oleoyl-N-methyl taurine sodium, molecular weight 425.6). The ink thus obtained was designated as magenta ink M-11 (Example 2).
Compound (4)

  The pKa of the low molecular dispersant is obtained by titrating a solution of 1 mol / L of the low molecular dispersant in a tetrahydrofuran / water (tetrahydrofuran: water = 3: 2 = V / V) solution with an aqueous hydrochloric acid solution. Obtained from the titration curve. The pKa of compound 2-1 was 5.8, and the pKa of compound 4 was 2 or less.

  Further, inks prepared by the same method as described above except that the SBR amount (styrene-butadiene-latex) of the magenta ink M-10 was changed to magenta inks M-12 to M-14 shown in Table 3 below, respectively. (Examples 3 to 5).

  Ink prepared in the same manner as in Table 3 except that the addition amount of the fluorosurfactant Zony1-FSA (manufactured by Dupont) was changed with respect to the total amount of the magenta ink M-10. Magenta inks M-15 to M-17 were used (Examples 6 to 8).

  Also, inks prepared in the same manner except that the pigment amount and SBR amount of magenta ink M-10 were changed were designated as magenta inks M-21 and M-22 in Table 3 below (Examples 9 and 10). (Unit:% by mass)

(1-2) Preparation of ink M-1 of Comparative Example 1 (in the case of no addition of polymer fine particles)
A magenta ink M-1 of Comparative Example 1 was prepared in the same manner as in Example 1 except that SBR (styrene-butadiene-latex) was not added (Comparative Example 1).

(1-3) Preparation of ink M-2 of Comparative Example 2 (when a polymer dispersant having a molecular weight exceeding 2000) is used
First, the following initial charge monomer (monomer, polymerization chain transfer agent, etc.) and 20 parts by mass of methyl ethyl ketone were charged into a reaction vessel to prepare a mixed liquid III, and nitrogen gas substitution was sufficiently performed.
(Initial charge monomer)
-Methacrylic acid: 8 parts by mass- Styrene: 21 parts by mass- Dodecyl methacrylate: 3 parts by mass (made by Shin-Nakamura Chemical Co., Ltd., trade name: NK ester M-230G)
M-230G: 5 parts by mass Methoxy-terminated polyethylene glycol (23 mol)
-Styrene macromer: 6 parts by mass (manufactured by Toa Gosei Co., Ltd., trade name: AS-6S (styrene homopolymerized macromer, number average molecular weight: 6000, polymerizable functional group: methacryloyloxy group))
Mercaptoethanol: 0.2 part by mass On the other hand, in the dropping funnel, the following dropping monomer (monomer, polymerization chain transfer agent, etc.), 60 parts by mass of methyl ethyl ketone, and 2,2′-azobis (2,4-dimethylvaleronitrile) ) 1.2 parts by mass was added to prepare a mixed solution IV, which was sufficiently substituted with nitrogen gas.

(Drip monomer)
-Methacrylic acid: 7 parts by mass-Styrene: 36 parts by mass-Dodecyl methacrylate: 4.6 parts by mass-M-230G: 5 parts by mass-Styrene macromer: 7 parts by mass-Mercaptoethanol: 0.2 parts by mass Under nitrogen atmosphere The mixture III in the reaction vessel was heated to 70 ° C. while stirring, and the mixture IV in the dropping funnel was gradually added dropwise over 3 hours. Two hours after the completion of the addition of the mixed solution IV, a solution in which 0.3 part by mass of 2,2′-azobis (2,4-dimethylvaleronitrile) was dissolved in 5 parts by mass of methyl ethyl ketone was added. Aged at 75 ° C. for 2 hours to obtain a polymer solution. Next, a part of this polymer solution was dried at 105 ° C. under reduced pressure for 2 hours to remove the solvent, thereby synthesizing the polymer dispersant of Comparative Example 2.

  Further, the weight average molecular weight of the polymer dispersant was measured by gel permeation chromatography using polystyrene as a standard substance and 50 mmol / L acetic acid-containing tetrahydrofuran as a solvent. As a result, the molecular weight was 35,000. 10% by mass of this polymer dispersant, 10% by mass of an organic pigment (same as in Example 1), 10% by mass of ethylene glycol, 10% by mass of diethylene glycol, and 1% by mass of Orphine E1010 were mixed. M-2 was prepared.

(1-4) Preparation of treatment liquid The following compounds were weighed and stirred to prepare a treatment liquid.
・ Diethylene glycol: 20.0g
・ Orphine E1010: 1.0g
・ 2-Pyrrolidone-5-carboxylic acid: 1.0 g
・ Sodium hydroxide: 0.25 g
-Ion exchange water: 77.8g
When the pH of the treatment solution was measured with a pH meter-WM-50EG manufactured by Toa DKK Co., Ltd., the pH was 3.5.

  For Examples 1 to 10 and Comparative Examples 1 and 2 prepared as described above, ink viscosity, dischargeability, fixability, abrasion resistance, and water resistance were evaluated by the following methods. The measurement results are shown in Table 4 described later.

(Measurement of viscosity)
It measured by DV-II + VISCOMETER made from BROOKFIELD.

(Evaluation of ejection properties)
The ink cartridge of PX-G920 manufactured by Seiko Epson Corporation was refilled with the ink shown in Table 1 above, and the nozzle check pattern was printed, and the ratio of ejected nozzles was evaluated. The evaluation results at this time are shown in Table 4 based on the following criteria.

○: discharge from all nozzles, Δ: discharge from 95% or more nozzles, ×: discharge from 90% or less nozzles [Fixability evaluation]
The ink was applied to A6 size Tokuhishi double-sided art N (manufactured by Mitsubishi Paper Industries Co., Ltd.) so that the ink thickness was about 5 μm (bar No. 3) and dried for 24 hours. Thereafter, a cellophane tape was applied to the sample to which the ink was applied, and the color transfer when peeled off was evaluated. The evaluation results are shown in Table 4 according to the following criteria.

◎: No color transfer, ○: Some color transfer, △: Color transfer (equivalent to EPSON PX-V500 ink), ×: Large color transfer [Evaluation of abrasion resistance]
Cover the sample coated with ink and coated with Tokishi Double-sided Art N (Mitsubishi Paper), press it with your finger, and rub the coated sample with the art paper placed on it 2 times in 20 cm. The color transfer was evaluated. The evaluation results at this time are shown in Table 4 based on the following criteria.

◎: No color transfer, ○: Some color transfer, △: Color transfer, ×: Large color transfer [Evaluation of water resistance]
A drop of water (30 μL) was dropped on a sample coated with the ink prepared in the fixability evaluation with a dropper, and the color transfer was evaluated after wiping off the water with a paddle dry after 1 minute. The evaluation results at this time are shown in Table 4 based on the following criteria.

  ○: No color transfer, △: Some color transfer

  Each of the inks of Examples 1 to 10 containing a low molecular dispersant and polymer fine particles (SBR) was able to achieve a low viscosity of 5.6 mPa · s or less. As a result, nozzle clogging did not occur, and good ink ejection properties were obtained. Further, the characteristics of these inks such as fixability to a recording medium, abrasion resistance, and water resistance were generally good although there were differences depending on the ink composition.

  However, it was found that the ink of Comparative Example 2 using a polymer dispersant having a molecular weight of 35000 has a high viscosity of 9.8 mPa · s, clogging occurs in some nozzles, and dischargeability is poor.

  Further, it was found that the ink of Comparative Example 1 containing no polymer fine particles (SBR) had low viscosity and good ink ejection properties, but poor fixability to a recording medium and abrasion resistance.

  As described above, the ink of the present invention containing both the low molecular dispersant and the polymer fine particles (SBR) is excellent in ink ejection stability, and excellent in fixability to a recording medium, abrasion resistance, water resistance, and the like. I understood it.

  Moreover, as a result of examining the influence of the SBR amount and the presence or absence of addition of a fluorosurfactant with respect to rubbing resistance and fixability, as shown in Examples 1, 3 to 5, 9, 10, and Comparative Example 1 in Table 4. In addition, it was found that the abrasion resistance decreases with the decrease in the amount of SBR. However, although the viscosity of the ink slightly increased as the amount of SBR in this example increased, it was confirmed that there was no effect on the ink ejection performance.

  Further, as shown in Examples 1 and 6 to 8, it was found that the addition of a fluorosurfactant further improves the abrasion resistance and the fixability.

  On the other hand, the ink of Comparative Example 1 containing neither SBR nor a fluorosurfactant was poor in both abrasion resistance and fixability.

  From the above, it has been found that SBR gives the fixing property of ink to art paper and binds the color materials to improve the abrasion resistance of the coated surface. Further, from the viewpoint of obtaining good ink ejection stability, fixing property, and abrasion resistance, at least the mass ratio P / C of the polymer fine particle mass P and the organic pigment mass C is 0.5 to 4.0. It is preferable that Further, it is presumed that the fluorosurfactant improves fixability and abrasion resistance by improving the slipperiness of the coated surface.

  As a result of examining the influence of the type of the low molecular dispersant for water resistance (see Examples 1 and 2 in Table 4), the ink of Example 1 containing a carboxylic acid group in the hydrophilic group of the low molecular dispersant is Although no color transfer was observed, in the ink of Example 2 containing a sulfonate group, some color transfer was observed. This is presumably because the carboxylic acid group is less likely to dissociate when water is added than the sulfonate group (because it is a weak acid).

  From the above, it was found that the ink using the low molecular dispersant containing a carboxylic acid group in the hydrophilic group has higher water resistance.

  Finally, the presence or absence of droplet ejection interference was evaluated using the ink set according to the present invention. Hereinafter, the inks of Examples 1 and 2 and the ink of Comparative Example 2 were examined.

[Evaluation of droplet ejection interference]
The head is fixed with IJET1000 made by MicroJet, and the special diamond double-sided art N (A6 size) with the processing solution applied with a No. 3 bar is placed on the movable stage, and the head is adjusted to a droplet volume of 120 pL. Discharge frequency 1kHz, stage operating speed 100m
The ink and / or treatment liquid was ejected under the conditions of m / s (the distance between the centers of adjacent dots was 100 μm and the time until the adjacent dod was ejected was set to 1 millisecond) to form a line.

  Thereafter, the storage time (evaluation of droplet ejection interference) of the dod shape was compared by changing the time from the deposition of the treatment liquid to the ejection of the ink. In addition, the preservability of the dot shape was evaluated by visually observing the sample on which the line was created by magnifying it 200 times with an optical microscope. The evaluation results at this time are shown in Table 5 based on the following criteria.

  (Double-circle): The boundary between dods can be confirmed easily.

  ○: The boundary between the dodds can be slightly confirmed.

  X: The boundary between dodds cannot be confirmed. (The dots are united and the droplets are in contact with each other.)

  As in Examples 1 and 2 in Table 5, when ink was ejected using an ink set composed of an ink and a treatment liquid, it was confirmed that high-quality dodds could be formed without causing ink ejection interference. In particular, when the treatment liquid of this example was used, the ink of Example 1 using a low molecular dispersant containing a carboxylic acid group had significantly less droplet ejection interference. This is presumably because aggregates were easily generated from the relationship between the dissociation degree of the low molecular dispersant and the acidity of the treatment liquid, thereby preventing bleeding.

  On the other hand, when only the ink of Comparative Example 2 was ejected, it was confirmed that the droplet ejection interference was such that the boundary between the dots could not be confirmed.

  As described above, it was found that the droplet ejection interference can be suppressed by using the ink set in which the ink of the present invention and the treatment liquid are combined.

  In this example, magenta was used as the organic pigment. B15: 3 and yellow pigment P.I. Even when other organic pigments such as Y155 are used, the effect of the present invention can be obtained satisfactorily.

  As described above, by applying the ink set, the image recording method, and the apparatus according to the present invention, it is possible to form an image with excellent ink ejection stability, high speed, high image quality, and high definition.

1 is an overall configuration diagram of an ink jet recording apparatus as one form of an image forming apparatus. FIG. 3 is a plan perspective view illustrating a structural example of a print head. It is a plane perspective view which shows the other structural example of a full line type print head. FIG. 4 is a cross-sectional view taken along line 4-4 in FIG. FIG. 3 is an enlarged view showing a nozzle arrangement of the print head shown in FIG. 2. It is the schematic which showed the structure of the ink supply system of an inkjet recording device. It is a principal block diagram showing the system configuration of the ink jet recording apparatus. It is the schematic diagram used in order to demonstrate the image formation process in the inkjet recording device of this example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Inkjet recording device, 11 ... Treatment liquid head, 12K, 12M, 12C, 12Y ... Print head, 15 ... Solvent absorption roller, 15A, 15E ... Porous member, 16 ... Recording medium, 33 ... Conveyor belt, 17 ... Heating unit, 110 ... treatment liquid, 120 ... ink, 124 ... film, 126 ... color material aggregate, 134 ... solvent

Claims (16)

An ink containing at least an organic pigment, a water-soluble organic solvent, and water, a treatment liquid that is applied to the recording medium in advance before applying the ink to the recording medium, and generates an aggregate when it comes into contact with the ink; An ink set comprising:
An ink set comprising a low molecular dispersant having a molecular weight of 2000 or less and polymer fine particles in the ink.   The ink set according to claim 1, wherein the treatment liquid is acidic.   3. The ink set according to claim 1, wherein the low molecular dispersant has a pKa of a dissociation constant Ka of 3 or more.   The ink set according to any one of claims 1 to 3, wherein the chemical structure of the low molecular dispersant contains a carboxylic acid group or a salt thereof. The ink set according to claim 1, wherein the low molecular dispersant is represented by the following general formula (1).
General formula (1)

(In General Formula (1), L ¹ represents a single bond or a divalent linking group, R ¹ represents a substituent, R ² and R ³ each represent a hydrogen atom or a substituent. Represents a hydrogen atom or a monovalent cation, and n represents an integer having 1 or more carbon atoms, provided that R ^{1 to} R ³ do not include a sulfonic acid group, and the total number of these carbon atoms is 13 or more.) The ink set according to claim 5, wherein L ^{1 in the} general formula (1) is an amide group, a sulfonamide group, an ester group, an ether group, or a sulfide group. The ink set according to claim 1, wherein the low molecular dispersant is represented by the following general formula (2) or (3).
General formula (2)

General formula (3)

(In General Formulas (2) and (3), R ¹ represents a substituent, R ² , R ³ , and R ⁴ each represent a hydrogen atom or a substituent. M represents a hydrogen atom or a monovalent cation. N represents an integer of 1 to 10 carbon atoms, provided that R ^{1 to} R ⁴ do not include a sulfonic acid group, and the total number of these carbon atoms is 13 or more.   The ink set according to any one of claims 1 to 7, wherein the polymer fine particles have a glass transition temperature Tg of 30 ° C or higher.   The ink set according to any one of claims 1 to 8, wherein the polymer fine particles are styrene latex or acrylic latex.   The mass ratio P / C of the mass P of the polymer fine particles contained in the ink and the mass C of the organic pigment contained in the ink is 0.5 to 4.0. The ink set of any one of -9.   The ink set according to claim 1, wherein the ink contains a fluorinated surfactant.   The ink set according to claim 1, wherein the ink set is an ink jet ink set. An image recording method using the ink set according to any one of claims 1 to 12,
An image recording method comprising: applying a treatment liquid of the ink set on a recording medium; and applying an ink of the ink set to the treatment liquid to form an image.   14. The image recording method according to claim 13, wherein the treatment liquid is acidic, and the acidity of the ink is changed by contact with the treatment liquid to produce an aggregate.   15. The image recording method according to claim 13, wherein the image recording method is an ink jet recording method. An image recording apparatus using the ink set according to any one of claims 1 to 12,
First applying means for applying a treatment liquid of the ink set to a recording medium;
Second application means for applying the ink of the ink set to the treatment liquid;
Heating means for heating the agglomerates generated by bringing the ink and the treatment liquid into contact with each other;
An image recording apparatus comprising:

Images