JP5811323B2 - Ink jet recording apparatus and ink composition - Google Patents

Description

  The present invention relates to an ink jet recording apparatus and an ink composition.

  2. Description of the Related Art Conventionally, an ink jet recording apparatus having a nozzle that ejects minute ink droplets for recording an image, characters, or the like on a recording medium is known. As an ink composition used in such an ink jet recording apparatus, those obtained by dissolving or dispersing various coloring materials such as dyes and / or pigments in a high-boiling organic solvent or water are widely used. Such a high boiling point organic solvent is excellent in low volatility and water retention capability, and thus contributes to prevention of drying of the nozzles of the inkjet recording head.

  An image recorded on a recording medium with an ink composition containing a high-boiling organic solvent may be difficult to dry. Therefore, a mechanism for heating the recording medium is provided in the ink jet recording apparatus to improve the drying property of the image recorded on the recording medium.

  By the way, among the ink compositions used in the ink jet recording apparatus, the ink composition containing a yellow color material is often inferior in weather resistance. For this reason, products using the same tend to fade when used outdoors. From such a point of view, development of a yellow pigment capable of achieving both high weather resistance and high color developability is in progress. For example, Patent Document 1 proposes an oil-based ink composition in which a yellow organic pigment is dispersed in an organic solvent.

JP 2010-1478 A

  However, an image recorded on a recording medium with an ink composition containing a high-boiling organic solvent may not be sufficiently dried even when a mechanism for heating the recording medium is used, and may not have excellent abrasion resistance. . When a non-ink-absorbing or low-ink-absorbing medium is used as the recording medium, the recorded image tends to have a noticeable reduction in the abrasion resistance.

  In order to solve the above problems, for example, when an ink composition containing a low boiling point solvent instead of a high boiling point organic solvent is used, the ink composition attached to the recording medium heats the recording medium. It is sufficiently dried by the mechanism to do. However, if a high boiling point solvent is not contained in the ink composition, the nozzles of the ink jet recording apparatus may be dried by a mechanism for heating the recording medium, resulting in clogging and the like.

  Thus, there is a trade-off between improving the drying property (fast drying property) of the image recorded on the recording medium and ensuring the ejection stability of the ink jet recording apparatus.

  By the way, as described above, development of a yellow pigment capable of achieving both high weather resistance and high color developability is underway. However, depending on the types of components contained in the ink composition, the yellow pigment contained in the ink composition may aggregate, resulting in a marked increase in the viscosity of the ink composition or a decrease in color developability of the recorded image. There was a case.

  Some embodiments according to the present invention can record an image excellent in quick-drying and abrasion resistance while achieving both high weather resistance and high color developability by solving at least a part of the above problems, and An ink jet recording apparatus having excellent ejection stability is provided.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following aspects or application examples.

[Application Example 1]
One aspect of the ink jet recording apparatus according to the present invention is:
C. I. Pigment yellow 213 or C.I. I. Pigment Yellow 155 and water, and an ink composition substantially free of alkyl polyols having a boiling point of 280 ° C. or higher at 1 atm,
A head having nozzle holes for discharging droplets of the ink composition;
A heating mechanism that heats the recording medium before or when the droplets discharged from the nozzle holes are attached to the recording medium;
Have

  The droplet discharge device of Application Example 1 can record an image excellent in quick-drying and abrasion resistance while achieving both high weather resistance and high color developability, and is excellent in ink discharge stability.

[Application Example 2]
In application example 1,
The recording medium can be a non-ink-absorbing or low-ink-absorbing recording medium.

[Application Example 3]
In application example 1 or application example 2,
Further, the ink composition contains a water-soluble organic solvent having a boiling point of 180 ° C. or higher and 250 ° C. or lower at 1 atm,
The content of the water-soluble organic solvent in the ink composition may be 15% by mass or more and 30% by mass or less.

[Application Example 4]
In any one of Application Examples 1 to 3,
The viscosity [Va (mPa · s)] of the ink composition when the mass of the ink composition is reduced by 20 mass% and the viscosity [Vb (mPa) of the ink composition before mass reduction at 20 ° C. S)] and the ratio (Va / Vb) can be 1.45 or less.

[Application Example 5]
In any one of Application Examples 1 to 4,
The nozzle hole may have a diameter of 15 μm to 25 μm.

[Application Example 6]
In any one of Application Examples 1 to 5,
The head is a piezo head,
The nozzle hole may eject the ink composition with a droplet amount of 3 pl or less.

[Application Example 7]
In any one of Application Examples 1 to 6,
The heating mechanism may be provided at a position facing the head.

[Application Example 8]
One aspect of the ink composition according to the present invention is:
A head having nozzle holes for discharging droplets of the ink composition;
A heating mechanism that heats the recording medium before or when the droplets discharged from the nozzle holes are attached to the recording medium;
An ink composition for use in an ink jet recording apparatus,
water and,
C. I. Pigment yellow 213 or C.I. I. Pigment Yellow 155,
Containing
It contains substantially no alkyl polyol having a boiling point of 280 ° C. or higher at 1 atm.

FIG. 2 is a perspective view schematically illustrating a configuration of a printer according to the embodiment of the invention. FIG. 2 is a schematic diagram schematically illustrating an arrangement of nozzles provided in a printer head according to an embodiment of the invention. FIG. 3 is a partial cross-sectional view schematically showing an internal configuration of a head according to an embodiment of the invention.

  Hereinafter, preferred embodiments of the present invention will be described. The embodiment described below describes an example of the present invention. In addition, the present invention is not limited to the following embodiments, and includes various modifications that are implemented within a range that does not change the gist of the present invention.

1. Ink Composition An ink jet recording apparatus according to an embodiment of the present invention ejects droplets of an ink composition. Hereinafter, the ink composition used in the ink jet recording apparatus according to this embodiment will be described.

  The ink composition used in the ink jet recording apparatus according to the present embodiment (hereinafter also simply referred to as “ink composition”) contains a yellow pigment and water, and has a boiling point of 280 ° C. or higher at 1 atm. Almost no alkyl polyols are contained.

  The ink composition according to the present embodiment is substantially free of alkyl polyols having a boiling point of 280 ° C. or higher at 1 atm. By including an alkyl polyol having a boiling point of 280 ° C. or higher at 1 atm, the drying property of the ink composition is greatly reduced. As a result, in various recording media, particularly in non-ink-absorbing or low-absorbing recording media, image fixability and abrasion resistance may be lowered. Examples of alkyl polyols having a boiling point of 280 ° C. or higher at 1 atm equivalent include glycerin having a boiling point of 290 ° C. at 1 atm. The alkyl polyol does not include an acetylene glycol surfactant described later.

  Further, it is preferable not to contain 1.5% by mass or more of an organic solvent having a boiling point of 280 ° C. or higher at 1 atm, more preferably not to contain 1.0% by mass or more of the organic solvent, It is particularly preferable not to include 0.5% by mass or more. An example of the organic solvent having a boiling point of 280 ° C. or higher at 1 atm is triethanolamine having a boiling point of 335 ° C. at 1 atm.

  In the present invention, “substantially free of A” means that the meaning that A is not intentionally added when the ink composition is produced, or the significance of adding A is sufficiently achieved. It means that it is not added in excess of the amount. Specific examples of “substantially free” include, for example, 1.0% by mass or more, preferably 0.5% by mass or less, more preferably 0.1% by mass or less, and still more preferably 0% by mass. 0.05% by mass or less, particularly preferably 0.01% by mass or less, more preferably 0.001% by mass or less. Hereinafter, each component used for this embodiment is demonstrated in detail.

1.1. Yellow Pigment The ink composition according to this embodiment includes C.I. I. Pigment yellow 213 or C.I. I. Pigment Yellow 155 is contained. The ink composition includes C.I. I. Pigment yellow 213 and C.I. I. Both pigment yellow 155 may be contained.

  C. I. Pigment yellow 213 and C.I. I. Pigment Yellow 155 has high weather resistance and high color development properties. In particular, any of these yellow pigments is excellent in dispersibility in a solvent containing water as a main component. Therefore, C.I. I. Pigment yellow 213 or C.I. I. By using Pigment Yellow 155 as an ink composition in which water is a main component, the dispersibility of these yellow pigments is improved and the color developability is remarkably improved. As a result, a recorded matter having both high weather resistance and high color developability can be obtained. Among the yellow pigments, C.I. I. Pigment Yellow 74, and C.I. I. Pigment Yellow 74 is not excellent in weather resistance, and is difficult to apply to low-absorption and non-absorption media such as printing paper and plastic media that are mainly assumed to be used outdoors. Further, as will be shown in Examples described later, the recording apparatus combined with the heating mechanism, the head, the water-soluble organic solvent contained in the ink and the like in the present invention has a C.I. I. C.I. a benzimidazolone pigment having the same kind of skeleton as CI Pigment Yellow 180. I. Pigment Yellow 155 is better. In addition, as shown also in the Example mentioned later, C.I. I. The same performance as CI Pigment Yellow 155, C.I. I. Pigment Yellow 213 is also demonstrated.

  In addition, as shown also in the Example mentioned later, when it is set as the non-aqueous ink composition which disperse | distributed said yellow pigment (CI pigment yellow 213 and CI pigment yellow 155) in the organic solvent, it is favorable. Color development cannot be obtained. One reason for this is that C.I. I. Pigment yellow 213 and C.I. I. It is considered that the dispersibility of CI Pigment Yellow 155 is not very good.

  The ink composition according to this embodiment is excellent in storage stability with little change in viscosity even when part of a solvent such as water contained in the ink composition evaporates. Therefore, when the ink composition according to this embodiment is applied to an ink jet recording apparatus, the occurrence of nozzle clogging or the like is reduced even if the ink jet recording apparatus is of a type that is particularly prone to nozzle drying by a heating mechanism. And the ink ejection stability is excellent.

  Further, the ink composition according to the present embodiment can be obtained by adding the evaporated solvent to the ink composition again even when a part of the solvent such as water contained in the ink composition is evaporated. I. Pigment yellow 213 and C.I. I. Since the pigment yellow 155 is easily redispersed in the solvent, the ink composition can be reused.

  As described above, the reason why the ink composition according to the present embodiment is excellent in storage stability and redispersibility is that even when the solvent in the ink composition is evaporated, C.I. I. Pigment yellow 213 and C.I. I. This is considered to be because Pigment Yellow 155 has good dispersibility and pigment particles hardly aggregate.

  The content of the yellow pigment in the ink composition according to this embodiment is preferably 3.5% by mass or more and 8% by mass or less, more preferably 3.5% by mass or more and 6% by mass or less, and particularly preferably 3.5% by mass. It is not less than mass% and not more than 5.5 mass%. When the total content of yellow pigments is in the above range, an image having both high weather resistance and high color developability is particularly easily obtained.

  C. I. Pigment Yellow 213 includes Nikkaji number J1,817,318B, an independent administrative agency “Science and Technology Promotion Organization” Nikkaji Web. Describes the following structural formula (1).

C. I. Pigment Yellow 155 is a Nikkaji number J62.474H, an independent administrative agency “
Japan Science and Technology Agency, Nikkaji Web. Is described as the following structural formula (2).

  C. I. The number average particle diameter d50 of CI Pigment Yellow 155 is preferably 40 nm or more and 350 nm or less from the viewpoint that a recorded matter having high color developability is easily obtained. The “number average particle diameter d50” in the present invention means that the cumulative existence probability of particles is 50% when the number-based particle size distribution measurement is performed by a particle size distribution measuring apparatus based on the laser diffraction scattering method. It means the particle diameter when it becomes. As a laser diffraction type particle size distribution measuring apparatus, for example, Nanotrac (manufactured by Microtrac, model “UPA-150”) can be cited.

  In order to apply the yellow pigment according to the present embodiment to the ink composition, it is necessary that the yellow pigment can be stably dispersed and held in water. As the method, a method of dispersing with a resin dispersant such as a water-soluble resin and / or a water-dispersible resin (hereinafter, a pigment treated by this method is referred to as “resin-dispersed pigment”), a water-soluble surfactant A method of dispersing with a surfactant of an agent and / or a water-dispersible surfactant (hereinafter, a pigment treated by this method is referred to as “surfactant-dispersed pigment”), and hydrophilic functional groups on the pigment particle surface In which water is dispersed and / or dissolved in water without a dispersing agent such as the above-mentioned resin or surfactant (hereinafter, the pigment treated by this method is referred to as “surface-treated pigment”). And the like). For the ink composition according to the present embodiment, any of the above-described resin-dispersed pigments, surfactant-dispersed pigments, and surface-treated pigments can be used, and a plurality of types can be mixed as necessary.

  Examples of the resin dispersant used for the resin dispersion pigment include polyvinyl alcohols, polyacrylic acid, acrylic acid-acrylonitrile copolymer, vinyl acetate-acrylic acid ester copolymer, acrylic acid-acrylic acid ester copolymer, and styrene. -Acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, styrene-α-methylstyrene-acrylic acid- Acrylate ester copolymer, styrene-maleic acid copolymer, styrene-maleic anhydride copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer, vinyl acetate-maleic acid ester copolymer Polymer, vinyl acetate-crotonic acid copolymer, vinyl acetate-acrylic Examples thereof include acid copolymers and salts thereof. Among these, a copolymer of a monomer having a hydrophobic functional group and a monomer having a hydrophilic functional group, and a polymer comprising a monomer having both a hydrophobic functional group and a hydrophilic functional group are preferable. As the form of the copolymer, any form of a random copolymer, a block copolymer, an alternating copolymer, and a graft copolymer can be used.

  Examples of the salt include basic compounds such as ammonia, ethylamine, diethylamine, triethylamine, propylamine, isopropylamine, dipropylamine, butylamine, isobutylamine, diethanolamine, triethanolamine, triisopropanolamine, aminomethylpropanol, and morpholine. Of the salt. The addition amount of these basic compounds is not particularly limited as long as it is equal to or more than the neutralization equivalent of the resin dispersant.

  The molecular weight of the resin dispersant is preferably in the range of 1,000 to 100,000 as the weight average molecular weight, and more preferably in the range of 3,000 to 10,000. When the molecular weight is in the above range, the yellow pigment is stably dispersed in water, and viscosity control when applied to the ink composition is easy.

  Moreover, it is preferable that it is the range of 50-300 as an acid value, and it is more preferable that it is the range of 70-150. When the acid value is in this range, the dispersibility of the yellow pigment in water can be stably secured, and the water resistance of the recorded matter recorded with the ink composition using the yellow pigment becomes good.

  Commercially available products can be used as the resin dispersant described above. Specifically, Joncryl 67 (weight average molecular weight: 12,500, acid value: 213), Joncryl 678 (weight average molecular weight: 8,500, acid value: 215), Joncryl 586 (weight average molecular weight: 4,600) , Acid value: 108), joncryl 611 (weight average molecular weight: 8,100, acid value: 53), joncryl 680 (weight average molecular weight: 4,900, acid value: 215), joncryl 682 (weight average molecular weight) : 1,700, acid value: 238), joncryl 683 (weight average molecular weight: 8,000, acid value: 160), joncryl 690 (weight average molecular weight: 16,500, acid value: 240) , Manufactured by BASF Japan Ltd.).

  The surfactant used in the surfactant-dispersed pigment includes alkane sulfonate, α-olefin sulfonate, alkyl benzene sulfonate, alkyl naphthalene sulfonate, acylmethyl taurate, and dialkyl sulfo oxalate. Anionic surfactants such as alkyl sulfate ester salts, sulfated olefins, polyoxyethylene alkyl ether sulfate ester salts, alkyl phosphate ester salts, polyoxyethylene alkyl ether phosphate ester salts, monoglycerite phosphate ester salts, Amphoteric surfactants such as alkyl pyridium salts, alkyl amino acid salts, alkyl dimethyl betaines, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl esters, polyoxyethylenes Alkylamide, glycerol alkyl esters, nonionic surfactants such as sorbitan alkyl esters.

  The amount of the resin dispersant or the surfactant added to the pigment is preferably 1 part by mass to 100 parts by mass, and more preferably 5 parts by mass to 50 parts by mass with respect to 100 parts by mass of the yellow pigment. By being in this range, the dispersion stability of the yellow pigment in water can be ensured.

As the surface-treated pigment, as the hydrophilic functional _{group, -OM, -COOM, -CO -,} - SO 3 M, -SO 2 NH 2, -RSO 2 M, -PO 3 HM, -PO 3 M 2 , —SO ₂ NHCOR, —NH ₃ , —NR ₃ (wherein M represents a hydrogen atom, an alkali metal, ammonium or organic ammonium, R represents an alkyl group having 1 to 12 carbon atoms, a substituent, And a phenyl group which may have or a naphthyl group which may have a substituent). These functional groups are physically and / or chemically introduced by grafting directly to the yellow pigment surface and / or via multivalent groups. Examples of the polyvalent group include an alkylene group having 1 to 12 carbon atoms, a phenylene group which may have a substituent, or a naphthylene group which may have a substituent.

In addition, as the surface-treated pigment, -SO ₃ M and / or -RSO ₂ M (M is a counter ion, hydrogen ion, alkali metal ion, ammonium ion is added to the surface of the yellow pigment by a treatment agent containing sulfur. , Or an organic ammonium ion) that has been surface-treated so as to be chemically bonded, that is, the yellow pigment has no active protons, no reactivity with sulfonic acid, and the yellow pigment is insoluble or hardly soluble. In the solvent, the yellow pigment is dispersed, and then the surface of the particle is chemically bonded to the particle surface by amidosulfuric acid or a complex of sulfur trioxide and a tertiary amine so that —SO ₃ M and / or —RSO ₂ M are chemically bonded. It is preferably one that has been treated so that it can be dispersed and / or dissolved in water.

  The functional group grafted on one yellow pigment may be single or plural kinds. The type and degree of the functional group to be grafted may be appropriately determined in consideration of the dispersion stability in the ink composition, the color density, the drying property on the front surface of the inkjet recording head, and the like.

  As a method of dispersing the above-mentioned resin dispersed pigment, surfactant dispersed pigment, and surface-treated pigment in water, a yellow pigment and water and a resin dispersant are used for the resin dispersed pigment, and a yellow pigment is used for the surfactant dispersed pigment. For water, surfactants, and surface-treated pigments, add surface-treated pigment and water, and water-soluble organic solvents and neutralizers, etc., if necessary. Ball mill, sand mill, attritor, roll mill, agitator mill, Henschel It can be performed by a conventionally used disperser such as a mixer, a colloid mill, an ultrasonic homogenizer, a jet mill or an ang mill.

1.2. Water The water contained in the ink composition according to the present embodiment is a main solvent, and it is preferable to use pure water or ultrapure water such as ion exchange water, ultrafiltration water, reverse osmosis water, and distilled water. In particular, it is preferable to use water sterilized by ultraviolet irradiation or addition of hydrogen peroxide in order to prevent generation of mold and bacteria and enable long-term storage of the ink composition.

  Note that the ink composition according to the present embodiment preferably contains 50% by mass or more of water. By containing 50% by mass or more of water, C.I. I. Pigment yellow 213 and C.I. I. Since the dispersibility of CI Pigment Yellow 155 is further improved, it is easy to obtain a recorded matter having high color developability.

1.3. Other components 1.3.1. Water-soluble organic solvent The ink composition according to the embodiment may contain a water-soluble organic solvent. Examples of the water-soluble organic solvent include polyhydric alcohols and pyrrolidone derivatives. These water-soluble organic solvents can be used singly or in combination of two or more.

  Among the water-soluble organic solvents, it is preferable to use a water-soluble organic solvent having a boiling point of 180 ° C. or more and 250 ° C. or less at 1 atmosphere, and a water-soluble organic having a boiling point of 185 ° C. or more and 225 ° C. or less at 1 atmosphere. It is more preferable to use a solvent. When the boiling point of the water-soluble organic solvent is within the above range, it is possible to ensure quick drying of the recorded image while reducing clogging of the nozzles of the ink jet recording apparatus.

  When a water-soluble organic solvent having a boiling point of 180 ° C. or higher and 250 ° C. or lower corresponding to 1 atm is added, the content thereof is 15% by mass or more and 30% by mass with respect to the total mass of the ink composition. Or less, more preferably 20% by mass or more and 30% by mass or less. When the content of the water-soluble organic solvent having a boiling point of 180 ° C. or more and 250 ° C. or less corresponding to 1 atm is within the above range, the speed of the recorded image is reduced while reducing clogging of the nozzles of the ink jet recording apparatus described above. The effect that the dryness can be secured may be further improved.

  Examples of polyhydric alcohols having a boiling point of 180 ° C. or more and 250 ° C. or less under 1 atm include 1,2-ethanediol [197 ° C.], 1,2-propanediol [188 ° C.], 1,3-propanediol. [210 ° C], 1,2-butanediol [194 ° C], 1,4-butanediol [230 ° C], 1,2-pentanediol [210 ° C], 1,5-pentanediol [242 ° C], 1 , 2-hexanediol [224 ° C.], 1,6-hexanediol [250 ° C.], 1,2-heptanediol [227 ° C.], 1,2-pentanediol [206 ° C.], 3-methyl-1,3 -Butanediol [203 ° C], 2-ethyl-2-methyl-1,3-propanediol [226 ° C], 2-methyl-1,3-propanediol [214 ° C], 2-ethyl-1,3- Hexane [244 ° C], 2-methyl-2-propyl-1,3-propanediol [230 ° C], 2,2-dimethyl-1,3-propanediol [210 ° C], 2-methylpentane-2, 4-diol [197 ° C.], diethylene glycol [244 ° C.], dipropylene glycol [232 ° C.] and the like, and other water-soluble organic solvents having a boiling point of 180 ° C. or more and 250 ° C. or less corresponding to 1 atm. γ-butyrolactone [204 ° C.], dimethyl sulfoxide [189 ° C.], 1,3-dimethyl-2-imidazolidinone [225 ° C.], diethylene glycol diethyl ether [185 ° C.], diethylene glycol monobutyl ether [230 ° C.] and the like. . The numerical value in parentheses represents a boiling point corresponding to 1 atm. Among these, 1,2-alkanediols are excellent in the action of increasing the wettability of ink with respect to a recording medium (particularly an ink non-absorbing or low-absorbing recording medium described later) and uniformly wetting it. An excellent image can be formed on the recording medium. When polyhydric alcohols are contained, the content is preferably 1% by mass or more and 25% by mass or less with respect to the total mass of the ink composition.

  Examples of pyrrolidone derivatives having a boiling point of 180 ° C. or more and 250 ° C. or less corresponding to 1 atm are N-methyl-2-pyrrolidone [204 ° C.], N-ethyl-2-pyrrolidone [212 ° C.], N-vinyl- Examples include 2-pyrrolidone [193 ° C.], 2-pyrrolidone [245 ° C.], and 5-methyl-2-pyrrolidone [248 ° C.]. The numerical value in parentheses represents a boiling point corresponding to 1 atm. Among these, 2-pyrrolidone is preferable in terms of ensuring the storage stability of the ink composition, promoting the film formation of the resin fixing agent, and relatively low odor. When the pyrrolidone derivative is contained, the content thereof is preferably 0.1% by mass or more and 25% by mass or less with respect to the total mass of the first ink. Further, if the inkjet recording apparatus according to the present embodiment is supposed to be printed on vinyl chloride media, in order to make the pyrrolidone derivative function as a vinyl chloride dissolution aid, the total mass of the ink composition Thus, it is preferably contained in an amount of 10% by mass to 25% by mass, more preferably 13% by mass or more and 25% by mass or less.

1.3.2. Surfactant The ink composition according to the present embodiment may contain a surfactant. By including a surfactant in the ink composition, the surface tension and the interfacial tension with the printer member in contact with the ink, such as nozzles, can be maintained appropriately. Therefore, when this is used in an ink jet recording apparatus, the ejection stability can be improved. In addition, there is an effect that the ink is uniformly spread so as not to cause unevenness of ink density and bleeding on the recording medium.

  The surfactant having such an effect is preferably a nonionic surfactant. Among the nonionic surfactants, silicone surfactants and / or acetylene glycol surfactants are more preferable.

  As the silicone surfactant, a polysiloxane compound or the like is preferably used, and examples thereof include polyether-modified organosiloxane. More specifically, BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-348 (above trade names, manufactured by Big Chemie Japan Co., Ltd.), KF-351A, KF- 352A, KF-353, KF-354L, KF-355A, KF-615A, KF-945, KF-640, KF-642, KF-643, KF-6020, X-22-4515, KF-6011, KF- 6012, KF-6015, KF-6017 (above trade names, manufactured by Shin-Etsu Chemical Co., Ltd.) and the like. When the silicone-based surfactant is contained, the content thereof is preferably 0.1% by mass or more and 2% by mass or less with respect to the total mass of the ink composition.

  As acetylene glycol surfactants, for example, Surfinol 104, 104E, 104H, 104A, 104BC, 104DPM, 104PA, 104PG-50, 104S, 420, 440, 465, 485, SE, SE-F, 504, 61, DF37 , CT111, CT121, CT131, CT136, TG, GA, DF110D (all trade names, manufactured by Air Products and Chemicals Inc.), Olfin B, Y, P, A, STG, SPC, E1004, E1010, PD- 001, PD-002W, PD-003, PD-004, EXP. 4001, EXP. 4036, EXP. 4051, AF-103, AF-104, AK-02, SK-14, AE-3 (all trade names, manufactured by Nissin Chemical Industry Co., Ltd.), acetylenol E00, E00P, E40, E100 (all trade names, Kawaken Fine Chemical Co., Ltd.). When the acetylene glycol surfactant is contained, the content thereof is preferably 0.1% by mass or more and 2% by mass or less with respect to the total mass of the ink composition.

1.3.3. Resin Particles The ink composition according to the present embodiment may contain resin particles. By including resin particles in the ink composition, an image having excellent abrasion resistance can be formed on the recording medium. In particular, in the ink composition according to the present embodiment, the resin particles are preferably contained in a fine particle state (that is, an emulsion state or a suspension state). By containing the resin particles in a fine particle state, it is easy to adjust the viscosity of the ink composition to an appropriate range in the ink jet recording method, and it is easy to ensure storage stability and ejection stability.

Examples of the resin particles include polymer particles that have an effect of forming a resin film and fixing on a recording medium. Examples of the component constituting the polymer particles having such an effect include polyacrylic acid ester or a copolymer thereof, polymethacrylic acid ester or a copolymer thereof, polyacrylonitrile or a copolymer thereof, polycyanoacrylate, and polyacrylamide. , Polyacrylic acid, polymethacrylic acid, polyethylene, polypropylene, polybutene, polyisobutylene, polystyrene or copolymers thereof, petroleum resin, chroman indene resin, terpene resin, polyvinyl acetate or copolymer thereof, polyvinyl alcohol, polyvinyl Acetal, polyvinyl ether, polyvinyl chloride or copolymer thereof, polyvinylidene chloride, fluororesin, fluoro rubber, polyvinyl carbazole, polyvinyl pyridine, polyvinyl imidazole Polybutadiene or a copolymer, polychloroprene, polyisoprene, and natural resins. Of these, those having both a hydrophobic part and a hydrophilic part in the molecular structure are particularly preferred.

  As the polymer particles as described above, those obtained by known materials and methods can be used. Commercially available products can also be used, for example, Microgel E-1002, Microgel E-5002 (trade name, manufactured by Nippon Paint Co., Ltd.), Boncoat 4001, Boncoat 5454 (trade name, manufactured by DIC Corporation), SAE1014 (trade name, manufactured by Nippon Zeon Co., Ltd.), Cybinol SK-200 (trade name, manufactured by Seiden Chemical Co., Ltd.), Jonkrill 7100, Jonkrill 390, Jonkrill 711, Jonkrill 511, Jonkrill 7001, Jonkrill 632 , John Krill 741, John Krill 450, John Krill 840, John Krill 74J, John Krill HRC-1645J, John Krill 734, John Krill 852, John Krill 7600, John Krill 775, John Krill 537J, John Krill 535, John Krill PDX-7630A, John Krill 352J, John Krill 352D, John Krill PDX-7145, John Krill 538J, John Krill 7640, John Krill 7641, John Krill 631, John Krill 790, John Krill 780, John Krill 7610 ( As mentioned above, trade names, manufactured by BASF Japan Ltd.) and the like can be mentioned.

  Said polymer particle is obtained by the method shown below, Any method may be sufficient and it may combine a some method as needed. As the method, a polymerization catalyst (polymerization initiator) and a dispersing agent are mixed in a monomer of a component constituting a desired polymer particle, and polymerization (that is, emulsion polymerization) is performed. A method of obtaining particles by dissolving in a water-soluble organic solvent and mixing the solution in water and then removing the water-soluble organic solvent by distillation, etc., dissolving the polymer in a water-insoluble organic solvent and dissolving the solution together with the dispersant in an aqueous solution And the like to obtain particles by mixing. Said method can be suitably selected according to the kind and characteristic of the polymer to be used. The dispersant that can be used for dispersing the polymer in a fine particle state is not particularly limited, but anionic surfactants (for example, sodium dodecylbenzenesulfonate, sodium lauryl phosphate, polyoxyethylene alkyl ether sulfate) Ammonium salts, etc.), nonionic surfactants (for example, polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkylphenyl ethers). These may be used alone or in combination of two or more. It can be used by mixing.

  The average particle diameter of the resin particles is preferably in the range of 5 nm to 400 nm, more preferably in the range of 50 nm to 200 nm, from the viewpoint of ensuring the storage stability and ejection stability of the ink composition.

  When the resin particles are contained, the content thereof is preferably 0.5% by mass or more and 10% by mass or less with respect to the total mass of the ink composition. When the content of the resin particles is in the above range, solidification and fixing of the ink composition on the recording medium can be promoted.

1.3.4. Wax Particles The ink composition according to this embodiment may contain wax particles. By adding wax particles, the abrasion resistance of the image can be improved.

  Examples of the components constituting the wax particles include plant and animal waxes such as carnauba wax, candeli wax, beeswax, rice wax, and lanolin; petroleum oils such as paraffin wax, microcrystalline wax, polyethylene wax, oxidized polyethylene wax, and petrolatum. Waxes; mineral waxes such as montan wax and ozokerite; synthetic waxes such as carbon wax, Hoechst wax, polyolefin wax, stearamide, and natural and synthetic wax emulsions such as α-olefin / maleic anhydride copolymers and blends Wax or the like can be used alone or in combination. Among these, preferred wax types are polyolefin waxes, particularly polyethylene wax and polypropylene wax. Commercially available products may be used as the wax particles, such as Nopcoat PEM17 (trade name, manufactured by San Nopco Co., Ltd.), Chemipearl W4005 (trade name, manufactured by Mitsui Chemicals, Inc.), AQUACER 515, and AQUACER 593 (above trade names, Big Chemie Japan). Etc.).

  The average particle diameter of the wax particles is preferably in the range of 5 nm to 400 nm, more preferably in the range of 50 nm to 200 nm, from the viewpoint of ensuring the storage stability and ejection stability of the ink composition.

  When the wax particles are contained, the content thereof is preferably 0.1% by mass or more and 5% by mass or less in terms of solid content with respect to the total mass of the ink composition. When the content of the wax particles is within the above range, the abrasion resistance of the image recorded on the recording medium may be further improved.

1.3.5. Polymerization initiator, polymerizable compound The ink composition according to this embodiment may contain a polymerization initiator, if necessary. For example, the ink may contain a compound having a polymerizable functional group (polymerizable compound). In that case, the ink can be polymerized by applying heat or irradiating with radiation. When it is necessary to further increase the polymerization rate, a thermal polymerization initiator or a radiation polymerization initiator can be added.

  The polymerization initiator may not necessarily be water-soluble, may be oil-soluble, or may be poorly soluble. This is because, for example, when the polymerization initiator is oil-soluble, the polymerization initiator is present in the oil phase in the water-based ink, and when it is poorly soluble, the polymerization initiator is, for example, After the image forming step, when water is removed to some extent on the recording medium, it comes into contact with the polymerizable functional group and can exhibit a desired action. Furthermore, the polymerization initiator may have a property of moving between phases, and can be appropriately selected according to the formulation of the ink and as necessary.

  Examples of the polymerization initiator include benzoin methyl ether, benzoin ethyl ether, isopropyl benzoin ether, isobutyl benzoin ether, 1-phenyl-1,2-propanedione-2- (o-ethoxycarbonyl) oxime, benzyl, diethoxyacetophenone, Examples include benzophenone, chlorothioxanthone, 2-chlorothioxanthone, isopropylthioxanthone, 2-methylthioxanthone, polychlorinated polyphenyl, and hexachlorobenzene.

  The polymerizable compound is not particularly limited, but is polyester acrylate, polyurethane acrylate, epoxy acrylate, polyether acrylate, oligo acrylate, alkyd acrylate, polyol acrylate, diethylene glycol diacrylate, neopentyl glycol diacrylate, 1,6-hexane. Diol diacrylate, hydroxypioperic acid ester neopentine glycol glycol diacrylate, trimethylolpropane triacrylate, pentaerythritol triacrylate, dipentaerythritol hexaacrylate, acroylmorpholine, 2-phenoxyethyl acrylate, hydrogen phthalate- ( 2,2,2-triacroyloxymethyl) ethyl, dipentaerystol polyacryle DOO, dipentaerythritol polyacrylate, N- vinylformamide, tripropylene glycol diacrylate, glycerin EO adduct triacrylate is go up.

1.3.6. Other components In addition to the components described above, the ink composition according to the present embodiment further improves the properties, and if necessary, a penetrating solvent, a humectant, an antiseptic / antifungal agent, pH A regulator, a chelating agent, an ultraviolet absorber, an oxygen absorber and the like can be added.

1.4. Physical Properties of Ink Composition The pH of the ink composition is preferably neutral or alkaline, and more preferably in the range of 7.0 to 10.0. If the pH is acidic, the storage stability and dispersion stability of the ink composition may be impaired. In addition, problems such as corrosion of metal parts used in the ink flow path in the ink jet recording apparatus are likely to occur. The pH can be adjusted to neutral or alkaline using the pH adjusting agent described above.

  The viscosity at 20 ° C. of the ink composition according to this embodiment is preferably from 1.5 mPa · s to 15 mPa · s. When the viscosity of the ink composition at 20 ° C. is within the above range, an appropriate amount of droplets of the ink composition are ejected from the nozzles of the inkjet recording apparatus, and the flying bending and scattering of the droplets can be further reduced. It can be suitably used for a recording apparatus. The viscosity of the ink composition can be measured by maintaining the temperature of the ink composition at 20 ° C. using a vibration viscometer VM-100AL (trade name, manufactured by Yamaichi Electronics Co., Ltd.).

The ink composition according to the present embodiment is not limited to the following test conditions. For example, 40 ml of the ink composition is put into a container having a capacity of 50 ml and is in contact with the atmosphere of the ink composition put into the container. When the area is 0.25πcm ² (where π is the circumference) and the ink is stored in an atmosphere at a temperature of 60 ° C. and a humidity of 50% RH, the ink when the mass of the stored ink composition is reduced by 20% by mass. The ratio [(Va / Vb)] of the viscosity [Va (mPa · s)] of the composition and the viscosity [Vb (mPa · s)] of the ink composition before mass reduction is 1.45 or less. It is preferable that it is 1.4 or less. When the viscosity ratio of the ink composition before and after storage is within the above range, even when a part of the solvent in the ink composition evaporates, an appropriate amount of ink composition droplets are ejected from the nozzle of the ink jet recording apparatus. Can be discharged. The viscosity of the ink composition before and after storage can be measured by keeping the temperature of the ink composition at 20 ° C. using a viscometer Physica MCR30 (manufactured by Anton Paar).

  The surface tension of the ink composition according to this embodiment is preferably 20 mN / m to 40 mN / m, more preferably 25 mN / m to 35 mN / m at 25 ° C. Within this range, ink ejection stability can be ensured, and appropriate wettability with respect to the recording medium can be ensured.

1.5. Method for Producing Ink Composition The ink composition according to the present embodiment is obtained by mixing the materials described above in an arbitrary order and removing impurities by filtering or the like as necessary. Here, the yellow pigment is preferably prepared in advance in a state of being uniformly dispersed in an aqueous medium and then mixed in view of ease of handling.

  As a method for mixing the respective materials, a method in which the materials are sequentially added to a container equipped with a stirring device such as a mechanical stirrer or a magnetic stirrer and stirred and mixed is preferably used. As a filtration method, centrifugal filtration, filter filtration, or the like can be performed as necessary.

2. Inkjet recording apparatus 2.1. Apparatus Configuration An ink jet recording apparatus according to an embodiment of the present invention includes a head having a nozzle hole for discharging a droplet of the ink composition described above, and before or before the droplet discharged from the nozzle hole is attached to a recording medium. And a heating mechanism for heating the recording medium at the time of attachment.

  Hereinafter, the ink jet recording apparatus according to the present embodiment will be described with reference to FIGS. In each drawing used for the following description, the scale of each member is appropriately changed to make each member a recognizable size. In the present embodiment, an inkjet printer (hereinafter simply referred to as “printer”) is illustrated as an inkjet recording apparatus.

  FIG. 1 is a perspective view illustrating a configuration of a printer 1 according to the present embodiment. A printer 1 shown in FIG. 1 is a serial printer. A serial printer is a printer in which a head is mounted on a carriage that moves in a predetermined direction, and droplets are ejected onto a recording medium as the head moves as the carriage moves.

  1 illustrates a serial printer, the present invention is not limited to this, and the inkjet recording apparatus according to the present invention may be, for example, a line printer. A line printer is one in which the head is formed wider than the width of the recording medium and the liquid droplets are ejected onto the recording medium without moving the head.

  As shown in FIG. 1, a printer 1 includes a carriage 4 on which a head 2 is mounted and an ink cartridge 3 is detachably mounted; a platen 5 that is disposed below the head 2 and that transports a recording medium P; A heating mechanism 6 for heating the recording medium, a carriage moving mechanism 7 for moving the carriage 4 in the medium width direction of the recording medium P, a medium feeding mechanism 8 for conveying the recording medium P in the medium feeding direction, It is what has. The printer 1 also has a control device CONT that controls the operation of the entire printer 1. The medium width direction is the main scanning direction (head scanning direction). The medium feeding direction is a sub-scanning direction (a direction orthogonal to the main scanning direction).

  The ink cartridge 3 according to this embodiment includes four independent cartridges. Any one of the four cartridges is filled with the ink composition described above. A cartridge other than the cartridge filled with the ink composition described above is filled with a desired ink composition (for example, a cyan ink composition, a magenta ink composition, a black ink composition, etc.). In the example of FIG. 1, the number of cartridges is four. However, the number of cartridges is not limited to this, and a desired number of cartridges can be mounted.

  The ink cartridge 3 is not limited to the one mounted on the carriage 4 as in the present embodiment, but instead, for example, is a type that is mounted on the housing side of the printer 1 and supplied to the head 2 via the ink supply tube. There may be.

  The carriage 4 is attached in a state of being supported by a guide rod 9 which is a support member installed in the main scanning direction. The carriage 4 is moved in the main scanning direction along the guide rod 9 by the carriage moving mechanism 7. In the example of FIG. 1, the carriage 4 moves in the main scanning direction. However, the present invention is not limited to this, and the carriage 4 may move in the sub scanning direction in addition to the movement in the main scanning direction. .

  If the heating mechanism 6 is provided at a position where the recording medium P can be heated, the installation position is not particularly limited. In the example of FIG. 1, the heating mechanism 6 is installed on the platen 5 at a position facing the head 2. More specifically, the heating mechanism 6 is installed at a position facing a nozzle surface 21A described later. Thus, when the heating mechanism 6 is installed at a position facing the head 2, the adhesion position of the droplet on the recording medium P can be reliably heated, so that the droplet adhering to the recording medium P can be efficiently removed. Can be dried and formed into a film.

  The heating mechanism 6 includes, for example, a print heater mechanism that heats the recording medium P in contact with a heat source, a mechanism that irradiates infrared rays or microwaves (electromagnetic waves having a maximum wavelength of about 2,450 MHz), hot air, A dryer mechanism or the like that sprays the air can be used.

  The recording medium P is heated by the heating mechanism 6 before or when the droplets ejected from the nozzle holes 17 adhere to the recording medium P. In this way, the droplets attached to the recording medium P can be quickly dried. On the other hand, drying of the ink composition near the nozzle of the head is promoted during recording on the recording medium. Control of various heating conditions (for example, heating timing, heating temperature, heating time, etc.) is performed by the control device CONT.

  It is preferable that the recording medium P is heated by the heating mechanism 6 so that the recording medium P maintains a temperature range of 40 ° C. or more and 60 ° C. or less. In the present invention, the temperature at which the recording medium is heated means the temperature of the surface of the recording medium in contact with the ink composition.

  The printer 1 may further have a second heating mechanism (not shown) in addition to the heating mechanism 6. The second heating mechanism is installed downstream of the heating mechanism 6 in the conveyance direction of the recording medium P. The second heating mechanism heats the recording medium P after the recording medium P is heated by the heating mechanism 6, that is, after the droplets ejected from the nozzle holes 17 adhere to the recording medium P. Is. As a result, it is possible to further promote film formation of the droplets of the ink composition adhering to the recording medium P. Any of the mechanisms described in the heating mechanism 6 (for example, a dryer mechanism) can be used as the second heating mechanism.

  The recording medium P is preferably heated by the second heating mechanism so that the recording medium P maintains a temperature range of 50 ° C. or more and 90 ° C. or less. The higher the heating temperature at this time, the more advantageous is the improvement of quick drying and abrasion resistance. However, when the temperature of the recording medium P exceeds 90 ° C., deformation may occur depending on the type of the recording medium P, and problems such as shrinkage of a recorded image may occur when the recording medium P is heated and cooled. . In addition, there are problems such as an increase in power consumption of the heater used for heating and an increase in exhaust heat from the printer due to the heating mechanism. Based on these problems, the upper limit of the temperature of the recording medium is 90 ° C. Is preferred.

  The linear encoder 10 detects the position of the carriage 4 in the main scanning direction with a signal. This detected signal is transmitted to the control device CONT as position information. The control device CONT recognizes the scanning position of the head 2 based on the position information from the linear encoder 10, and controls the recording operation (discharge operation) by the head 2. Further, the control device CONT is configured to be able to variably control the moving speed of the carriage 4.

  FIG. 2 is a schematic view showing the nozzle surface 21A in the head 2 according to the present embodiment.

  As shown in FIG. 2, the head 2 includes a nozzle surface 21A. A plurality of nozzle rows 16 are arranged on the nozzle surface 21 </ b> A which is also an ink ejection surface. The plurality of nozzle rows 16 includes a plurality of nozzle holes 17 for ejecting ink for each nozzle row.

  The diameter of the nozzle hole 17 is preferably 15 μm or more and 25 μm or less. If the nozzle hole is too large, drying of the ink composition in the vicinity of the nozzle may proceed, which is not preferable. On the other hand, when the nozzle hole is too small, it is difficult to control minute droplets. When the diameter of the nozzle hole 17 is within the above range, the ink composition of the present invention can be easily ejected from the nozzle hole 17 in an appropriate amount.

  The printer 1 is preferably a device that can eject the ink composition from the nozzle holes 17 with droplets of 3 pl or less, more preferably 1.6 pl or less.

  FIG. 3 is a partial cross-sectional view showing the internal configuration of the head 2 in the present embodiment.

  As shown in FIG. 3, the head 2 includes a head main body 18 and a flow path forming unit 22 connected to the head main body 18. The flow path forming unit 22 includes a vibration plate 19, a flow path substrate 20, and a nozzle substrate 21, and forms a common ink chamber 29, an ink supply port 30, and a pressure chamber 31. Furthermore, the flow path forming unit 22 includes an island portion 32 that functions as a diaphragm portion, and a compliance portion 33 that absorbs pressure fluctuation in the common ink chamber 29. In the head main body 18, an accommodation space 23 for accommodating the drive unit 24 together with the fixing member 26 and an internal flow path 28 for guiding ink to the flow path forming unit 22 are formed.

  According to the above-described configuration, that is, the piezo-type head 2, when a drive signal is input to the drive unit 24 via the cable 27, the piezoelectric element 25 expands and contracts. As a result, the diaphragm 19 is deformed (moved) in a direction toward and away from the pressure chamber 31. For this reason, the volume of the pressure chamber 31 changes and the pressure of the pressure chamber 31 containing ink fluctuates. Ink is ejected from the nozzle holes 17 due to this pressure fluctuation.

  Returning to FIG. 1, a home position serving as a scanning start point of the head 2 is set in an area outside the platen 5 in the movement range of the head 2. At this home position, a maintenance unit 11 including a cap member 12 and a wiping member 13 is provided.

  The maintenance unit 11 increases the viscosity by capping the head 2 with the cap member 12 other than the recording operation to suppress ink evaporation, and preliminarily ejecting ink from the nozzle holes 17 of the head 2 to the cap member 12. Prevention of clogging of the nozzle holes 17 due to ink, adjustment of the meniscus of the nozzle holes 17 to normally discharge ink from the head 2, and driving a suction pump (not shown) after capping the head 2 with the cap member 12. Forcibly sucking ink with increased viscosity from each nozzle hole 17 and adhering dust etc. to adjust the meniscus so that ink is normally ejected from the head 2 (head cleaning), and the nozzle surface 21A of the head 2 By wiping (see FIG. 2) with the wiping member 13, Or removing the deposited ink or thickened ink or the like, it has a wiping operation for performing the purge process to re-adjust the meniscus to destroy the meniscus of the nozzle hole 17, configured to run.

  In the ink jet recording apparatus according to the present embodiment, a non-ink-absorbing or low-ink-absorbing recording medium can be suitably used. Since the printer 1 has the heating mechanism 6 and uses the above-described ink composition that is easy to dry on the recording medium P, the printer 1 can be used for a recording medium that does not absorb ink and has low ink absorption. An image having excellent dryness and abrasion resistance can be recorded.

  As a non-ink-absorbing recording medium, for example, a plastic film coated with a base material such as a plastic film or paper that has not been surface-treated for inkjet printing (that is, an ink-absorbing layer is not formed) is coated. And those having a plastic film adhered thereto. Examples of the plastic here include polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, and polypropylene. Examples of the recording medium having low ink absorption include printing paper such as art paper, coated paper, and matte paper. In addition to the above recording medium, a non-ink-absorbing or low-absorbing recording medium such as metal or glass may be used.

  Here, in this specification, “a non-ink-absorbing or low-ink-absorbing recording medium” means “the water absorption amount from the start of contact to 30 msec1 / 2 in the Bristow method is 10 mL / m 2 or less. Recording medium ". This Bristow method is the most popular method for measuring the amount of liquid absorbed in a short time, and is also adopted by the Japan Paper Pulp Technology Association (JAPAN TAPPI). For details of the test method, refer to Standard No. of “JAPAN TAPPI Paper Pulp Test Method 2000”. 51 "Paper and paperboard-Liquid absorbency test method-Bristow method".

  The ink jet recording apparatus according to the present embodiment has a heating mechanism and uses the above-described ink composition. Therefore, the ink jet recording apparatus is excellent in ejection stability, and has both high weather resistance and high color developability, and also has abrasion resistance. In addition, an image having excellent drying properties can be recorded.

2.2. Image Recording Method An image recording method according to an embodiment of the present invention includes a heating process for heating a recording medium using the inkjet recording apparatus described above, and a recording medium by discharging droplets of the ink composition described above. Adhering to. In the present invention, “image” indicates a print pattern formed from a group of dots, and includes text printing and solid printing. Hereinafter, an image recording method using the printer 1 will be specifically described.

  First, the recording medium P is heated to a temperature range of 40 ° C. or more and 60 ° C. or less by the heating mechanism 6. Then, the ink composition is ejected as droplets from the nozzle holes 17 of the printer 1, and the droplets adhere to the heated recording medium P. Thereby, at least a part of the volatile components contained in the ink composition attached to the recording medium P is quickly evaporated and scattered, and a film made of the ink composition is formed. In this way, a desired image can be formed on the recording medium P. The heating of the recording medium P by the heating mechanism 6 may be performed before or when the droplets ejected from the nozzle holes 17 are attached to the recording medium P.

  Note that the image formed on the recording medium P can be sufficiently dried in a short time by the above-described process, and an image excellent in abrasion resistance can be obtained by promoting the film formation of the image. However, the second heating mechanism ( When used together with the heating mechanism 6, the effect of improving the quick-drying property and abrasion resistance of the image may be further enhanced.

  The recording medium is heated by the second heating mechanism (not shown) as follows. Specifically, the recording medium on which the image is formed is heated to a temperature range of 50 ° C. or more and 90 ° C. or less by a second heating mechanism (not shown) provided in the printer 1, thereby recording the recording medium. The ink composition adhering to is further dried. As a result, the image on the recording medium P can be further dried, and the film formation of the image further proceeds, so that an image having excellent abrasion resistance can be obtained.

  The heating time of the recording medium is not particularly limited as long as volatile components present in the ink composition can be evaporated and scattered, and an ink film can be formed. The heating time of the recording medium should be set appropriately in consideration of the solvent used, the printing speed, and the like. Can do.

3. EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to these examples.

3.1. Preparation of ink composition 3.1.1. Preparation of pigment dispersion First, the inside of a 2000 ml separable flask equipped with a stirrer, a reflux tube, a temperature sensor, and a dropping funnel was sufficiently purged with nitrogen, and then 200.0 parts by mass of diethylene glycol monomethyl ether was placed in the separable flask. The temperature was raised to 80 ° C. with stirring. Next, 200.0 parts by mass of diethylene glycol monomethyl ether, 483.0 parts by mass of cyclohexyl acrylate (hereinafter referred to as “CHA”), 66.6 parts by mass of methacrylic acid (hereinafter referred to as “MAA”), acrylic acid in a dropping funnel 50.4 parts by mass (hereinafter referred to as “AA”) and 4.8 parts by mass of t-butylperoxy (2-ethylhexanoate) (hereinafter referred to as “BPEH”) were added, and the mixture was heated at 80 ° C. for 4 hours. And dropped into a separable flask. After completion of dropping, the mixture was held at 80 ° C. for 1 hour, 0.8 parts by mass of BPEH was added, and the reaction was further performed at 80 ° C. for 1 hour. After completing the aging, diethylene glycol monomethyl ether was removed by distillation under reduced pressure. Thereafter, 600.0 parts by mass of methyl ethyl ketone (hereinafter referred to as “MEK”) was added to obtain a polymer composition solution for inkjet ink having a resin solid content of 50%. A portion of the thus obtained ink-jet ink polymer composition solution was taken and dried for 1 hour in a high-temperature dryer at 105 ° C., and then the solid acid value of the ink-jet ink polymer composition obtained was It was 130 mgKOH / g, and the weight average molecular weight was 34,000. Next, 6.0 parts by mass of a 30% aqueous sodium hydroxide solution is added to 120.0 parts by mass of the polymer composition solution for inkjet ink, and the mixture is stirred with a high-speed disper for 5 minutes. I. 480.0 parts by mass of the dispersion containing Pigment Yellow 213 was added and stirred with a high-speed disper for 1 hour to obtain a pigment dispersion.

  Note that C.I. I. Pigment yellows 155, 139, 185, 180, and 74 were obtained in the same manner as described above to obtain pigment dispersions.

3.1.2. Preparation of Ink Composition Inks having different material compositions of yellow color in the material compositions shown in Table 1 and Table 2 below using the pigment dispersion prepared in “3.1.1. Preparation of Pigment Dispersion” A composition was prepared. For each ink composition, the materials shown in the table are placed in a container, mixed and stirred for 2 hours with a magnetic stirrer, and then filtered with a membrane filter having a pore size of 5 μm to remove impurities such as dust and coarse particles. It was prepared by. In addition, all the numerical values in Table 1 and Table 2 indicate mass%. The ink compositions of Comparative Examples 5 and 6 shown in Table 2 were prepared according to the ink composition examples described in JP 2010-1478 A.

In addition, each material described by the brand name in Table 1 and Table 2 is as follows.
EPG 1456 (Mitsui Chemicals, binder resin)
・ AQUACER-539 (by Big Chemie Japan Co., Ltd., paraffin wax agent)
・ BYK-348 (Bic Chemie Japan, silicone surfactant)
・ Paraloid B60 (Rohm & Haas, acrylic binder resin)

3.2. Evaluation test and evaluation results 3.2.1. Viscosity change rate of ink (1) Evaluation test 40 ml of the prepared ink compositions of Examples 1 to 4 and Comparative Examples 1 to 2 were put into a sample bottle (manufactured by AS ONE, caliber 10 mmΦ, capacity 50 ml), and sample bottle In a state where the cap was opened, it was stored in a constant temperature and humidity chamber at a temperature of 60 ° C. and a humidity of 50% RH. In addition, the area where the ink composition in the sample bottle was in contact with the atmosphere was 0.25πcm ² .

  Then, the viscosity [Va (mPa · s)] when the weight of the ink composition in the sample bottle is reduced by 5 mass%, 10 mass%, 15 mass%, and 20 mass% is measured, and the ink before storage is measured. The viscosity change rate [(Va / Vb) × 100 (%)] from the viscosity [Vb (mPa · s)] of the composition was determined. The viscosity of the ink composition before and after storage was measured by keeping the temperature of the ink composition at 20 ° C. using a viscometer Physica MCR30 (manufactured by Anton Paar).

  Table 3 shows the viscosity change rate.

(2) Evaluation Results As shown in Table 3, it was shown that the ink compositions of Examples 1 to 4 had a low viscosity change rate due to evaporation of the solvent. This is presumably because there is little aggregation of pigment particles due to evaporation of the solvent.

  On the other hand, the ink compositions of Comparative Examples 1 and 2 significantly increased in viscosity as the solvent evaporated. Thus, it is estimated that the reason why the ink composition of Comparative Example 2 was thickened was that the dispersibility of the pigment was destroyed and aggregation of the pigment particles occurred.

3.2.2. Evaluation of nozzle clogging (1) Evaluation test Each of the prepared ink compositions of Examples 1 to 4 and Comparative Examples 1 to 2 was an ink jet printer (trade name “PX-G5000” manufactured by Seiko Epson Corporation). The ink cartridge was filled, and the ink flow path in the head was filled with the ink composition. Then, the ink cartridge was removed from the printer, and the printer was stored for 48 hours in a constant temperature and humidity chamber at a temperature of 40 ° C. and a humidity of 25% RH without capping the head with a cap member.

  After that, the printer is taken out from the constant temperature and humidity chamber, and printing of the nozzle pattern and the cleaning operation of the head on the recording medium (product name “P” manufactured by Fuji Xerox Co., Ltd.) are performed from all the nozzles in this order. This was repeated until the discharge was confirmed. The nozzle pattern was printed by changing the droplet weight (per droplet) of the ink ejected from the nozzle holes to 1.6 pl, 7.3 pl, and 22.5 pl.

The evaluation results are shown in Table 4. The evaluation criteria are as follows.
A: Ink ejection from all nozzles was confirmed within 3 cleaning operations B: Ink ejection from all nozzles was confirmed in cleaning operations 4 to 6 times C: Cleaning operations 7 to 11 times In the following, ink ejection from all nozzles was confirmed D: Ink ejection from all nozzles was confirmed after 12 cleaning operations or more

(2) Evaluation Results As shown in Table 4, the ink compositions of Examples 1 to 4 are nozzles even when the weight of droplets ejected from the nozzle holes is small (droplet weight: 1.6 pl). It has been shown that pore clogging can be recovered in a short period of time. The reason why the nozzle clogging can be recovered in a short period of time is considered to be because the ink compositions of Examples 1 and 2 are less likely to cause ink thickening due to evaporation of the solvent. Therefore, even when the nozzle holes of the ink jet recording apparatus are heated by the heating mechanism, the ink ejection stability is improved by using these ink compositions.

  On the other hand, the ink compositions of Comparative Examples 1 and 2 have a long period of time to recover from clogging of the nozzle holes, particularly when the weight of the liquid droplets discharged from the nozzle holes is small (droplet weight: 1.6 pl). This has been shown. From this, it was shown that the ink compositions of Comparative Example 1 and Comparative Example 2 are liable to cause ink thickening due to evaporation of the solvent and are not excellent in ejection stability.

3.2.3. Ink reliability (dry solidification)
(1) Evaluation test 0.2 ml of the prepared ink compositions of Examples 1 to 4, Comparative Examples 1 to 3, Comparative Example 7, and Comparative Example 8 were placed in a 9 ml capacity sample bottle (manufactured by ASONE CORPORATION, aperture 10 mmΦ). ) And stored for 1 hour in an atmosphere of a predetermined temperature and a humidity of 50% RH with the cap of the sample bottle opened. The ink was stored under each temperature condition with the storage temperature being 40 ° C., 50 ° C., and 60 ° C.

  Thereafter, the same amount of solvent as the amount reduced from each ink was added, and then stirred for 10 minutes to evaluate whether the components in the ink could be redispersed. In addition, ion exchange water was added to the ink compositions of Examples 1 to 4 and Comparative Examples 1 to 3 as a reduced solvent. Further, to the ink compositions of Comparative Examples 7 to 8, γ-butyrolactone, diethylene glycol diethyl ether and tetraethylene glycol dimethyl ether were added as reduced solvents so as to have the composition ratios shown in Table 2.

The evaluation results are shown in Table 5. The evaluation criteria are as follows.
A: The components contained in the ink composition are completely redispersed. B: Solid matter is observed in the ink composition. C: The ink composition is solidified.

(2) Evaluation results As shown in Table 5, the ink compositions of Examples 1 to 4, Comparative Example 2, Comparative Example 3, Comparative Example 7, and Comparative Example 8 are not affected by evaporation of a part of the ink solvent. By adding the solvent again, the components contained therein could be redispersed and had good properties.

  On the other hand, when the storage temperature was increased, the ink composition of Comparative Example 1 was not suitable for practical use because it was difficult to redisperse the contained components even when the solvent was added again.

3.2.4. Scrub resistance of images (1) Preparation of evaluation sample A part of an ink jet printer (Seiko Epson Corporation, “PX-G5000”) is modified, and a heater capable of changing the temperature is attached to the paper guide section to record an image. Sometimes, a recording medium (trade name “Cold Laminate Film PG-50L”, manufactured by Ramie Corporation, polyester film) can be adjusted by heating. Then, the prepared ink cartridges of Examples 1 to 4, Comparative Examples 1 to 3, and Comparative Examples 5 to 8 were filled in the dedicated cartridge of the printer.

  Then, the surface temperature of the recording medium was heated to a predetermined temperature using a heater attached to the paper guide portion of the printer. Next, with this temperature held, an operation of ejecting droplets of the ink composition from the nozzles of the printer and depositing the droplets on the recording medium is performed, and a solid pattern image is formed on the recording medium. A formed evaluation sample was obtained.

  The image recording conditions were resolution: vertical 720 dpi × horizontal 720 dpi, and Duty 100%. Further, the temperature of the recording medium during recording was set to 50 ° C. and 60 ° C., and images were recorded under each temperature condition.

Here, the “duty value” is a value calculated by the following equation.
duty (%) = number of actual ejection dots / (vertical resolution × horizontal resolution) × 100
(In the formula, “number of actual ejection dots” is the number of actual ejection dots per unit area, and “vertical resolution” and “horizontal resolution” are resolutions per unit area.)

(2) Evaluation Test Immediately after returning the evaluation sample obtained as described above to room temperature (25 ° C.), the Gakushin type friction fastness tester (trade name “AB-301” manufactured by Tester Sangyo Co., Ltd.) Was used, and the recorded image was rubbed with a friction element attached with a white cotton cloth for friction (Kanakin No. 3) under the conditions of a load of 500 g and a friction frequency of 50 times, and the surface state of the image was visually observed.

The evaluation results are shown in Table 6. The evaluation criteria are as follows.
A: Image surface is not scratched and image peeling is not observed B: Image surface scratch is observed, but image peeling is not observed C: Image surface scratch is observed, image peeling Is accepted

(3) Evaluation Results As shown in Table 6, the images obtained using the ink compositions of Comparative Examples 7 and 8 were ink compositions of Example 1, Example 2, and Comparative Examples 1 to 3. There was a tendency that the image was not superior in abrasion resistance than the image obtained by using the product. The reason for this is considered that the solvent contained in the ink compositions of Comparative Examples 7 and 8 is hard to evaporate and the film formation of the image is insufficient. Also, it can be seen from Example 3 and Example 4 that the abrasion resistance is reduced by increasing the amount of the water-soluble organic solvent. When a very high boiling solvent such as glycerin is added, the abrasion resistance is greatly reduced. It was found from Comparative Example 5 and Comparative Example 6.

3.2.5. Color development of image (1) Preparation of evaluation sample Except that the temperature of the recording medium at the time of recording was only 60 ° C., “3.2.4. Abrasion resistance of image (1) Preparation of evaluation sample” In the same manner as described above, an evaluation sample on which a patch pattern (Duty 100%) was recorded was prepared using the ink compositions of Examples 1-2, Comparative Examples 1-4, and Comparative Examples 7-8.

(2) Evaluation test The patch pattern of the obtained evaluation sample was measured with a spectrophotometer ("Gretag Macbeth SPM50" manufactured by Gretag), and the color difference display method L ^* a ^* b ^* color specification specified by CIE The coordinates of the system were obtained. The conditions at that time were the light source D50, no light source filter, the viewing angle was 2 °, and the white standard was absolute white. From the obtained value, the saturation C ^* [C ^* = ((a ^* ) ² + (b ^* ) ² ) ^1/2 ] of the patch was determined based on the following criteria.

Table 7 shows the evaluation results. The evaluation criteria are as follows.
A: 102 or more B: 100 or more and less than 102 C: 98 or more and less than 100 D: less than 98

(3) Evaluation Results As shown in Table 7, the images recorded using the ink compositions of Example 1, Example 2, Comparative Example 2 to Comparative Example 4 were excellent in color developability. On the other hand, the images recorded using the ink compositions of Comparative Example 1, Comparative Example 7, and Comparative Example 8 were insufficient in color developability.

  The ink compositions of Comparative Example 7 and Comparative Example 8 use the same pigments (CI Pigment Yellow 213, CI Pigment Yellow 155) as in Example 1 and Example 2. The color developability was not excellent. From this, C.I. I. Pigment yellow 213 and C.I. I. It was shown that CI Pigment Yellow 155 is preferably used for an ink whose main component is water as a solvent rather than an ink whose main component is an organic solvent as a solvent.

3.2.6. Weather resistance of image (1) Preparation of evaluation sample Except for adjusting the duty so that the initial OD value is 0.5, 1.0, and the maximum value, and performing the temperature of the recording medium at the time of recording only at 60 ° C. In the same manner as in “3.2.4. (Rubbing resistance of image) (1) Preparation of evaluation sample”, the ink compositions of Examples 1-2, Comparative Examples 1-4, and Comparative Examples 7-8 were used. An evaluation sample on which an image was recorded was obtained.

(2) Evaluation test The obtained evaluation sample is put into a chamber of a xenon weather meter (manufactured by Suga Test Instruments Co., Ltd.), and under the test conditions shown in Table 8 below, “light irradiation 40 minutes” → “light irradiation + water rain” A cycle test of “20 minutes” → “light irradiation 60 minutes” → “water rain 60 minutes” was performed. This cycle test was conducted continuously for 2 weeks, and the evaluation sample was taken out after 2 weeks.

  And the taken-out evaluation sample was left to stand in a general environment for 1 hour. After standing, the OD value of each evaluation sample is measured using a Gretag densitometer (manufactured by Gretag Macbeth Co., Ltd.), the residual ratio (%) of the OD value is obtained, and the initial OD value is 0.5, 1.0, the maximum value. Of these three images, the image with the lowest survival rate was evaluated.

Table 9 shows the evaluation results. The evaluation criteria are as follows.
A: OD value remaining rate is 85% or more B: OD value remaining rate is 70% or more and less than 85% C: OD value remaining rate is 55% or more and less than 70% D: OD value remaining rate is less than 55%

(3) Evaluation results The ink compositions of Example 1, Example 2, Comparative Example 7, and Comparative Example 8 were C.I. I. Pigment yellow 213 or C.I. I. Pigment Yellow 155 is contained. Therefore, as shown in Table 9, images formed using these ink compositions were excellent in weather resistance.

  On the other hand, the ink compositions of Comparative Examples 1 to 4 are C.I. I. Pigment yellow 213 and C.I. I. None of Pigment Yellow 155 is contained. Therefore, as shown in Table 9, it was shown that images formed using these ink compositions had insufficient weather resistance.

3.2.7. Summary of Evaluation Results From the above evaluation results, it was shown that the ink compositions of Examples 1 to 4 are excellent in storage stability and can form images having both high weather resistance and high color developability. Further, when the ink compositions of Examples 1 to 4 are applied to an ink jet recording apparatus equipped with a heating mechanism, it is shown that an image excellent in quick drying property and abrasion resistance can be recorded while sufficiently maintaining ejection stability. It was.

  The present invention is not limited to the embodiments described above, and various modifications are possible. For example, the present invention includes substantially the same configuration (for example, a configuration having the same function, method, and result, or a configuration having the same purpose and effect) as the configuration described in the embodiment. In addition, the invention includes a configuration in which a non-essential part of the configuration described in the embodiment is replaced. In addition, the present invention includes a configuration that achieves the same effect as the configuration described in the embodiment or a configuration that can achieve the same object. In addition, the invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 1 ... Printer, 2 ... Head, 3 ... Ink cartridge, 4 ... Carriage, 5 ... Platen, 6 ... Heating mechanism, 7 ... Carriage moving mechanism, 8 ... Medium feed mechanism, 9 ... Guide rod, 10 ... Linear encoder, 11 ... Maintenance unit, 12 ... cap member, 13 ... wipe member, 16 ... nozzle row, 17 ... nozzle hole, 18 ... head body, 19 ... vibrating plate, 20 ... channel substrate, 21 ... nozzle substrate, 21A ... nozzle surface, 22 ... Flow path forming unit, 23 ... Accommodating space, 24 ... Drive unit, 25 ... Piezoelectric element, 26 ... Fixing member, 27 ... Cable, 28 ... Internal flow path, 29 ... Common ink chamber, 30 ... Ink supply port, 31 ... Pressure chamber, 32 ... island part, 33 ... compliance part, CONT ... control device

Claims (9)

C. I. Pigment Yellow 213 and water, and an ink composition not containing 1.0 mass% or more of an alkyl polyol having a boiling point of 280 ° C. or higher at 1 atm,
A head having nozzle holes for discharging droplets of the ink composition;
A heating mechanism that heats the recording medium before or when the droplets discharged from the nozzle holes are attached to the recording medium;
An ink jet recording apparatus. In claim 1,
The inkjet recording apparatus, wherein the recording medium is a non-ink-absorbing or low-ink-absorbing recording medium. In claim 1 or claim 2,
Further, the ink composition contains a water-soluble organic solvent having a boiling point of 180 ° C. or higher and 250 ° C. or lower at 1 atm,
An ink jet recording apparatus, wherein the content of the water-soluble organic solvent in the ink composition is 15% by mass or more and 30% by mass or less. In any one of Claims 1 thru | or 3,
40 ml of the ink composition is put into a container having a capacity of 50 ml, and the area of the ink composition put into the container that is in contact with the atmosphere is 0.25πcm ² (π is the circumference), and the temperature is 60 ° C. and the humidity is 50% RH. In the case where the ink composition is stored under an atmosphere, the viscosity [Va (mPa · s)] at 20 ° C. of the ink composition when the mass of the stored ink composition is reduced by 20 mass% and the ink composition before the mass reduction. The ratio (Va / Vb) to the viscosity [Vb (mPa · s)] at 20 ° C. of the product is 1.45 or less. In any one of Claims 1 thru | or 4,
An ink jet recording apparatus, wherein the nozzle hole has a diameter of 15 μm or more and 25 μm or less. In any one of Claims 1 thru | or 5,
The head is a piezo head,
The nozzle hole is an ink jet recording apparatus capable of ejecting the ink composition with a droplet amount of 3 pl or less. In any one of Claims 1 thru | or 6,
The said heating mechanism is an inkjet recording device provided in the position facing the said head. In any one of Claims 1 thru | or 7,
Further, an ink jet recording apparatus comprising a second heating mechanism for heating the recording medium after droplets discharged from the nozzle holes adhere to the recording medium . A head having nozzle holes for discharging droplets of the ink composition;
A heating mechanism that heats the recording medium before or when the droplets discharged from the nozzle holes are attached to the recording medium;
An ink composition for use in an ink jet recording apparatus,
water and,
C. I. Pigment Yellow 213,
Containing
An ink composition containing no 1.0% by mass or more of an alkyl polyol having a boiling point of 280 ° C. or higher at 1 atm.

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