JP7400423B2 - Inkjet recording method and inkjet recording device - Google Patents

Description

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

An inkjet recording method is known in which an image is recorded on a recording medium by ejecting minute ink droplets from the nozzle of an inkjet head of an inkjet recording device, and its use in the sign printing field and high-speed label printing field is also being considered. There is. When recording an image on a recording medium with low ink absorption (for example, art paper or coated paper) or a recording medium with no ink absorption (for example, plastic film), the ink is From the viewpoint of safety, etc., the use of water-based resin ink compositions containing resin emulsions (hereinafter sometimes simply referred to as "water-based ink compositions" or "water-based inks") is being considered.

For example, attempts have been made to quickly fix a water-based ink composition and obtain excellent image quality by using a reaction liquid that has the effect of coagulating components contained in the water-based ink composition.

JP2019-081351A

However, as a result of the inventor's study, in the case of a water-based ink composition that is too reactive when it comes into contact with the reaction liquid, the reaction liquid mist may fly to the nozzle of the inkjet head, or when the recording medium comes into contact with the nozzle. , there was a tendency for the aqueous ink composition to have poor ejection, and for the abrasion resistance and glossiness of the recorded matter to deteriorate.

However, even if an aqueous ink composition with slightly lower reactivity is used in consideration of this point, even though an image of the same color is formed, the color differs depending on the area on the recording medium, so-called in-plane color difference. The following phenomenon occurred, and it was still unsatisfactory in terms of good recovery from nozzle clogging and ability to suppress in-plane color difference.

(1) One aspect of the inkjet recording method according to the present invention is
An inkjet recording method using an inkjet recording device, the method comprising:
a processing liquid adhesion step of adhering a processing liquid containing a flocculant to a recording medium;
an ink adhesion step of ejecting an aqueous ink composition containing a coloring material from an inkjet head and adhering it to the recording medium;
Equipped with
The inkjet recording device includes:
a recording medium support section that supports the recording medium;
a heating mechanism that heats the recording medium support section;
Equipped with
The ink adhering step is performed on the recording medium supported and heated by the recording medium supporter,
In the ink adhering step, the recording medium is heated to a maximum temperature of 28.0° C. or more and 45.0° C. or less on the surface of the recording medium supported by the recording medium supporting portion and facing the inkjet head. ,
The water-based ink composition has a ratio of 0.1% by mass of the water-based ink composition to the treatment liquid relative to the absorbance B at the maximum peak wavelength of a mixed liquid in which 0.1% by mass of the water-based ink composition is mixed with pure water. The ratio (A/B) of absorbance A at the wavelength of the 1% by mass mixed liquid is 0.5 or more and 0.95 or less,
In the inkjet recording method, the recording medium support section has a flat support surface that supports the recording medium.

(2) In the above aspect (1),
The ink adhesion step may be performed by performing main scanning and sub-scanning on the recording medium a plurality of times.

(3) In the above aspect (1) or (2),
In the ink adhering step, a temperature difference in an in-plane surface temperature distribution of a portion of the recording medium supported by the recording medium supporting portion and facing the inkjet head may be 8.0° C. or less. .

(4) In any of the above aspects (1) to (3),
The recording medium support section may be heated by the heating mechanism from a side opposite to the support surface of the recording medium support section.

(5) In any of the above aspects (1) to (4),
The average zeta potential of the coloring material in the aqueous ink composition may be -65.0 mV or more and -50.0 mV or less.

(6) In any of the above aspects (1) to (5),
The width in the direction perpendicular to the conveying direction of the recording medium may be 0.5 m or more.

(7) In any of the above aspects (1) to (6),
The width of the recording medium support portion in the direction perpendicular to the conveyance direction of the recording medium may be larger than the width in the direction perpendicular to the conveyance direction of the recording medium.

(8) In any of the above aspects (1) to (7),
A member constituting the support surface of the recording medium support portion may have a thickness of 2.0 mm or more and 10.0 mm or less.

(9) In any of the above aspects (1) to (8),
The ink adhesion step may include a blowing step of blowing air onto the recording medium to which the aqueous ink composition has been adhered by a blowing mechanism.

(10) In the above aspect (9),
The wind speed blown onto the recording medium may be 1.0 m/sec or more.

(11) In the above aspect (9) or (10),
The temperature of the air blown onto the recording medium may be 45.0° C. or lower.

(12) In any of the above aspects (1) to (11),
The ratio (A/B) may be 0.7 or more and 0.9 or less.

(13) In any of the above aspects (1) to (2),
The thickness of the recording medium may be 40.0 μm or more.

(14) In any of the above aspects (1) to (13),
The aqueous ink composition may not contain more than 1.0% by mass of an organic solvent having a normal boiling point of more than 280.0°C.

(15) In any of the above aspects (1) to (14),
The support surface may be in contact with the recording medium over an area of 90.0% or more of the area of the portion of the support surface that supports the recording medium and faces the inkjet head.

(16) One aspect of the recording device according to the present invention is
The inkjet recording method according to any one of the above embodiments (1) to (15) is performed.

(17) One aspect of the inkjet recording method according to the present invention is
An inkjet recording method using an inkjet recording device, the method comprising:
a processing liquid adhesion step of adhering a processing liquid containing a flocculant to a recording medium;
an ink adhesion step of ejecting an aqueous ink composition containing a coloring material from an inkjet head and adhering it to the recording medium;
Equipped with
The inkjet recording device includes:
a recording medium support section that supports the recording medium;
a heating mechanism that heats the recording medium support section;
Equipped with
The ink adhering step is performed on the recording medium heated and supported by the recording medium supporter,
The recording medium support section has a flat support surface that supports the recording medium,
The water-based ink composition has an absorbance A at a maximum peak wavelength in a range of 380.0 nm or more and 680 nm or less of a mixed liquid obtained by mixing 0.1% by mass of the water-based ink composition with respect to pure water. The ratio (A/B) of the mixed liquid obtained by mixing 0.1% by mass of the aqueous ink composition to the absorbance B at the maximum peak wavelength is 0.5 or more and 0.95 or less,
In the ink adhering step, the recording medium is heated to a maximum temperature of 28.0° C. or more and 45.0° C. or less on the surface of the recording medium supported by the recording medium supporting portion and facing the inkjet head. Ru.

FIG. 1 is a schematic diagram of an example of an inkjet recording apparatus according to an embodiment. 1 is a schematic diagram of a carriage and its surroundings in an example of an inkjet recording apparatus according to an embodiment. FIG. 1 is a block diagram of an example of an inkjet recording apparatus according to an embodiment. FIG. 1 is a schematic cross-sectional view schematically showing a portion of a line-type recording device. FIG. 2 is a perspective view schematically showing an example of a recording medium support portion with a flat support surface.

Some embodiments of the present invention will be described below. The embodiment described below describes an example of the present invention. The present invention is not limited to the following embodiments, but also includes various modifications that may be implemented within the scope of the invention. Note that not all of the configurations described below are essential configurations of the present invention.

1. Inkjet Recording Method An inkjet recording method according to one embodiment of the present invention is an inkjet recording method performed using an inkjet recording device, and includes a treatment liquid application step of applying a treatment liquid containing an aggregating agent to a recording medium, and a treatment liquid application step of applying a coloring material. an ink adhering step of ejecting an aqueous ink composition containing the ink from an inkjet head and adhering it to the recording medium. They will be explained in order below.

1.1. Recording Medium The recording medium used in the inkjet recording method of this embodiment is not particularly limited. However, since the effects of the inkjet recording method of this embodiment are more pronounced, it is more preferable to use a low-absorption or non-absorption recording medium.

A low-absorption or non-absorption recording medium refers to a recording medium that does not absorb ink at all or hardly absorbs ink. The term "low absorbency or non-absorbent recording medium" refers to "a recording medium in which the amount of water absorbed in the Bristow method from the start of contact to 30 msec ^1/2 is 10 mL/m ² or less". This Bristow method is a popular method for measuring the amount of liquid absorbed in a short period of time, and is also adopted by the Japan Paper and Pulp Technology Association (JAPAN TAPPI). Details of the test method can be found in the standard No. of "JAPAN TAPPI Paper and Pulp Test Method 2000 Edition". 51 "Paper and Paperboard - Liquid Absorption Test Methods - Bristow Method". On the other hand, a liquid-absorbing recording medium refers to a recording medium that does not fall under the category of non-liquid-absorbing or low-liquid-absorbing. In addition, in this specification, liquid non-absorbency, liquid low absorption property, and liquid absorption property may be simply referred to as non-absorption property, low absorption property, and absorption property.

Recording media with such low or non-absorbent properties include those that do not have an ink-absorbing ink-receiving layer on the recording surface, and those that have a coating layer that has low ink-absorbency on the recording surface. One example is the medium.

Non-liquid-absorbing recording media include films, plates, etc. of polymers such as polyvinyl chloride, polyethylene terephthalate, polycarbonate, polystyrene, polyurethane, polyethylene, polypropylene, polyvinyl acetal, and blend compositions of two or more thereof. Films and plates of cellulose acetate, cellulose triacetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose nitrate, etc., foils and plates of metals such as iron, silver, copper, aluminum, etc., or plates and films on which these metals are vapor-deposited. Examples include foils and plates made of alloys such as stainless steel and brass, and glass plates.

Examples of recording media with low liquid absorption include recording media provided with a coating layer (receptive layer) for receiving liquid on the surface. For example, the surface of the above film or plate is coated with a hydrophilic polymer, etc. , and those coated with particles of silica, titanium, etc. together with a binder (for example, a hydrophilic polymer such as polyvinyl alcohol or polyvinylpyrrolidone). In addition, examples of low liquid absorbency recording media whose base material is paper include printing papers such as art paper, coated paper, and matte paper.

Examples of the liquid-absorbing recording medium include paper such as plain paper and inkjet paper, sheets having an ink-receiving layer, cloth, and the like.

The recording medium may be colorless and transparent, semitransparent, colored and transparent, colored and opaque, achromatic and opaque, and the like. Further, the recording medium itself may be colored, translucent, or transparent. Further, the recording medium may be in the form of a bag or a sheet. Further, the recording medium may be subjected to surface treatment such as corona treatment or primer treatment in advance, and these surface treatments may improve the fixability of images from the recording medium.

The planar size of the recording medium used in this embodiment is not particularly limited. The width in the direction perpendicular to the conveying direction when used in an inkjet recording device is not particularly limited, but it is suitable for a relatively large inkjet recording device, and in that case, it is preferably 0.5 m or more, more preferably 0.5 m or more. .7m or more.

The thickness of the recording medium is also not particularly limited, but from the viewpoint of improving the conveyance of the recording medium in an inkjet recording apparatus, it is preferably 40.0 μm or more, more preferably 70.0 μm or more, and even more preferably 80.0 μm. That's all. On the other hand, the upper limit is not limited, but is preferably 300 μm or less, more preferably 200 μm or less, even more preferably 100 μm or less, and particularly preferably 80 μm or less.

1.2. Treatment Liquid Adhering Step The inkjet recording method of this embodiment includes a step of applying a treatment liquid containing an aggregating agent to a recording medium.

1.2.1. Treatment liquid The treatment liquid contains a flocculant.

1.2.1.1. Coagulant The treatment liquid contains a coagulant that coagulates the components of the aqueous ink composition. The aggregating agent has the effect of coagulating the coloring material and resin particles by reacting with components such as the coloring material contained in the water-based ink composition and the resin particles that may be contained in the water-based ink composition. However, the degree of aggregation of coloring materials and resin particles by the flocculant varies depending on the type of flocculant, coloring material, and resin particles. It can be adjusted by surface treatment etc. The flocculant has the effect of, for example, increasing the color development of the coloring material, increasing the fixing properties of the resin particles, and/or increasing the viscosity of the aqueous ink composition on the recording medium.

Examples of the flocculant include, but are not limited to, metal salts, acids, cationic compounds, etc. As the cationic compound, cationic resins (cationic polymers), cationic surfactants, etc. are used. be able to. Among these, polyvalent metal salts are preferred as metal salts. As the cationic compound, a cationic resin is preferred. Examples of acids include organic acids and inorganic acids, with organic acids being preferred. Therefore, it is preferable that the flocculant be selected from cationic resins, organic acids, and polyvalent metal salts because the obtained image quality, abrasion resistance, etc. are particularly excellent.

The metal salt is preferably a polyvalent metal salt, but metal salts other than polyvalent metal salts can also be used. Among these flocculants, it is preferable to use at least one selected from metal salts and organic acids because of its excellent reactivity with components contained in the ink. Furthermore, among the cationic compounds, it is preferable to use cationic resins because they are easily soluble in the processing liquid. Moreover, it is also possible to use multiple types of flocculants in combination.

A polyvalent metal salt is a compound composed of a divalent or higher valent metal ion and an anion. Examples of the divalent or higher-valent metal ions include ions such as calcium, magnesium, copper, nickel, zinc, barium, aluminum, titanium, strontium, chromium, cobalt, and iron. Among the metal ions constituting these polyvalent metal salts, at least one of calcium ions and magnesium ions is preferred from the viewpoint of excellent cohesiveness of the components of the ink.

The anion constituting the polyvalent metal salt is an inorganic ion or an organic ion. That is, the polyvalent metal salt in the present invention is composed of an inorganic ion or an organic ion and a polyvalent metal. Examples of such inorganic ions include chloride ions, bromide ions, iodine ions, nitrate ions, sulfate ions, and hydroxide ions. Examples of organic ions include organic acid ions, such as carboxylic acid ions.

Note that the polyvalent metal compound is preferably an ionic polyvalent metal salt, and in particular, when the polyvalent metal salt is a magnesium salt or a calcium salt, the stability of the treatment liquid becomes better. Further, the counter ion of the polyvalent metal may be either an inorganic acid ion or an organic acid ion.

Specific examples of the above polyvalent metal salts include calcium carbonate such as heavy calcium carbonate and light calcium carbonate, calcium nitrate, calcium chloride, calcium sulfate, magnesium sulfate, calcium hydroxide, magnesium chloride, magnesium carbonate, barium sulfate, and chloride. Examples include barium, zinc carbonate, zinc sulfide, aluminum silicate, calcium silicate, magnesium silicate, copper nitrate, calcium propionate, calcium acetate, magnesium acetate, aluminum acetate, and the like. These polyvalent metal salts may be used alone or in combination of two or more. Note that these metal salts may have hydration water in their raw material form.

Examples of metal salts other than polyvalent metal salts include monovalent metal salts such as sodium salts and potassium salts, such as sodium sulfate and potassium sulfate.

Examples of organic acids include poly(meth)acrylic acid, acetic acid, glycolic acid, malonic acid, malic acid, maleic acid, ascorbic acid, succinic acid, glutaric acid, fumaric acid, citric acid, tartaric acid, lactic acid, sulfonic acid, Suitable examples include orthophosphoric acid, pyrrolidonecarboxylic acid, pyronecarboxylic acid, pyrrolecarboxylic acid, furancarboxylic acid, pyridinecarboxylic acid, coumaric acid, thiophenecarboxylic acid, nicotinic acid, derivatives of these compounds, or salts thereof. . One type of organic acid may be used alone, or two or more types may be used in combination. Salts of organic acids or inorganic acids that are metal salts are included in the above metal salts.

Examples of inorganic acids include sulfuric acid, hydrochloric acid, nitric acid, and phosphoric acid. The inorganic acids may be used alone or in combination of two or more.

Examples of the cationic resin (cationic polymer) include cationic urethane resins, cationic olefin resins, cationic amine resins, and cationic surfactants. The cationic polymer is preferably water-soluble.

As the cationic urethane resin, commercial products can be used, such as Hydran CP-7010, CP-7020, CP-7030, CP-7040, CP-7050, CP-7060, CP-7610 (trade name , manufactured by Dainippon Ink and Chemicals Co., Ltd.), Superflex 600, 610, 620, 630, 640, 650 (product name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Urethane Emulsion WBR-2120C, WBR-2122C (product name, (manufactured by Taisei Fine Chemical Co., Ltd.) etc. can be used.

The cationic olefin resin has an olefin such as ethylene or propylene in its structural skeleton, and known resins can be appropriately selected and used. Further, the cationic olefin resin may be in the form of an emulsion in which it is dispersed in a solvent containing water, an organic solvent, or the like. As the cationic olefin resin, commercially available products can be used, such as Arrowbase CB-1200 and CD-1200 (trade name, manufactured by Unitika Co., Ltd.).

As the cationic amine resin (cationic polymer), any resin having an amino group in its structure may be used, and known resins can be appropriately selected and used. Examples include polyamine resins, polyamide resins, polyallylamine resins, and the like. A polyamine resin is a resin having an amino group in its main skeleton. Polyamide resin is a resin having an amide group in its main skeleton. Polyallylamine resin is a resin having a structure derived from an allyl group in the main skeleton of the resin.

In addition, as a cationic polyamine resin, Unisense KHE103L manufactured by Senka Co., Ltd. (hexamethylene diamine/epichlorohydrin resin, 1% aqueous solution pH approximately 5.0, viscosity 20 to 50 (mPa・s), solid content concentration 50 (mass% aqueous solution), Unisense KHE104L (dimethylamine/epichlorohydrin resin, 1% aqueous solution pH approximately 7.0, viscosity 1 to 10 (mPa s), solid content concentration 20 mass% aqueous solution), etc. . Further, specific examples of commercially available cationic polyamine resins include FL-14 (trade name, manufactured by SNF), ARAFIX 100, 251S, 255, 255LOX (trade name, manufactured by Arakawa Chemical Co., Ltd.), and DK-6810. , 6853, 6885; WS-4010, 4011, 4020, 4024, 4027, 4030 (product name, manufactured by Seiko PMC), Papiogen P-105 (product name, manufactured by Senka), Sumiraze Resin 650 (30), 675A , 6615, SLX-1 (trade name, manufactured by Taoka Chemical Industry Co., Ltd.), Catiomaster (registered trademark) PD-1, 7, 30, A, PDT-2, PE-10, PE-30, DT-EH, EPA -SK01, TMHMDA-E (trade name, manufactured by Yokkaichi Gosei Co., Ltd.), and Jetfix 36N, 38A, 5052 (trade name, manufactured by Satoda Kako Co., Ltd.).

Polyallylamine resins include, for example, polyallylamine hydrochloride, polyallylamine amide sulfate, allylamine hydrochloride/diallylamine hydrochloride copolymer, allylamine acetate/diallylamine acetate copolymer, allylamine acetate/diallylamine acetate copolymer, allylamine hydrochloride/dimethyl Allylamine hydrochloride copolymer, allylamine/dimethylallylamine copolymer, polydiallylamine hydrochloride, polymethyldiallylamine hydrochloride, polymethyldiallylamine amide sulfate, polymethyldiallylamine acetate, polydiallyldimethylammonium chloride, diallylamine acetate/sulfur dioxide copolymer, diallyl Examples include methylethylammonium ethyl sulfate/sulfur dioxide copolymer, methyldiallylamine hydrochloride/sulfur dioxide copolymer, diallyldimethylammonium chloride/sulfur dioxide copolymer, diallyldimethylammonium chloride/acrylamide copolymer, and the like.

Examples of cationic surfactants include primary, secondary, and tertiary amine salt type compounds, alkylamine salts, dialkylamine salts, aliphatic amine salts, benzalkonium salts, and quaternary ammonium salts. , quaternary alkylammonium salts, alkylpyridinium salts, sulfonium salts, phosphonium salts, onium salts, imidazolinium salts, and the like. Specifically, for example, hydrochlorides and acetates of laurylamine, coconut amine, rosinamine, etc., lauryltrimethylammonium chloride, cetyltrimethylammonium chloride, benzyltributylammonium chloride, benzalkonium chloride, dimethylethyllauryl ammonium ethyl sulfate, Dimethylethyloctylammonium ethyl sulfate, trimethyllauryl ammonium hydrochloride, cetylpyridinium chloride, cetylpyridinium bromide, dihydroxyethyl laurylamine, decyldimethylbenzylammonium chloride, dodecyldimethylbenzylammonium chloride, tetradecyldimethylammonium chloride, hexadecyldimethylammonium chloride , octadecyldimethylammonium chloride and the like.

A plurality of types of these flocculants may be used. In addition, if at least one of polyvalent metal salts, organic acids, and cationic resins is selected among these flocculants, the flocculation effect will be better, resulting in images of higher quality (especially with better color development). can be formed.

The total content of flocculants in the treatment liquid is, for example, 0.1% by mass or more and 20% by mass or less, and preferably 1% by mass or more and 20% by mass or less, based on the total mass of the treatment liquid. , more preferably 2% by mass or more and 15% by mass or less. Note that even when the flocculant is shared in a solution or a dispersion, the solid content is preferably within the above range. When the content of the aggregating agent is 1% by mass or more, the ability of the aggregating agent to agglomerate the components contained in the aqueous ink composition is sufficiently obtained. Further, when the content of the flocculant is 20% by mass or less, the solubility and dispersibility of the flocculant in the treatment liquid becomes better, and the storage stability of the treatment liquid can be improved.

Even if the organic solvent contained in the treatment liquid is highly hydrophobic, the solubility of the flocculant in the treatment liquid will be good. It is preferable to use the above amount, and it is more preferable to use the amount of 3 g or more and 80 g or less.

1.2.1.2. Other ingredients In addition to the flocculant, the treatment liquid should include organic solvents, surfactants, additives, preservatives/mold inhibitors, rust preventives, chelating agents, viscosity modifiers, and antioxidants, as long as they do not impair functionality. It may also contain components such as antifungal agents and antifungal agents.

(water)
The treatment liquid may contain water. Water is a component that evaporates and scatters during drying. The water is preferably purified water such as ion-exchanged water, ultrafiltrated water, reverse osmosis water, distilled water, etc., or ultrapure water from which ionic impurities have been removed as much as possible. Furthermore, it is preferable to use water that has been sterilized by ultraviolet irradiation or hydrogen peroxide addition, since this can suppress the growth of mold and bacteria when the treatment liquid is stored for a long period of time.

The treatment liquid may be a so-called aqueous composition containing water as a main solvent and containing 40% by mass or more of water, which is preferable. In this way, the treatment liquid has the advantage that odor is suppressed and that it is good for the environment because its composition is 40% by mass or more, preferably 50% by mass or more of water.

(Organic solvent)
The treatment liquid according to this embodiment may contain an organic solvent. By including an organic solvent, for example, it may be possible to improve the drying properties of the recorded matter or the fastness of the image. Furthermore, by including an organic solvent, the discharge stability of the treatment liquid can be improved. The organic solvent is preferably a water-soluble organic solvent.

Further, one of the functions of the organic solvent is to improve the wettability of the processing liquid to the recording medium and to increase the moisture retention property of the processing liquid. In addition, it lowers the surface tension of the treatment liquid, making it easier to separate and fly as droplets from the nozzle when ejected from an inkjet head, improving wettability on the recording medium and making the ink droplets spread better.

Examples of the organic solvent include esters, alkylene glycol ethers, cyclic esters, nitrogen-containing solvents, and polyhydric alcohols. Examples of the nitrogen-containing solvent include cyclic amides and acyclic amides. Examples of acyclic amides include alkoxyalkylamides and the like.

As esters, ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monomethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate,
Glycol monoacetates such as propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether acetate, methoxybutyl acetate, ethylene glycol diacetate, diethylene glycol diacetate, propylene glycol diacetate, dipropylene glycol diacetate, ethylene glycol acetate propionate , ethylene glycol acetate butyrate, diethylene glycol acetate butyrate, diethylene glycol acetate propionate, diethylene glycol acetate butyrate, propylene glycol acetate propionate, propylene glycol acetate butyrate, dipropylene glycol acetate butyrate, dipropylene glycol acetate propionate Examples include glycol diesters such as .

Examples of cyclic esters include β-propiolactone, γ-butyrolactone, δ-valerolactone, ε-caprolactone, β-butyrolactone, β-valerolactone, γ-valerolactone, β-hexanolactone, γ-hexanolactone. , δ-hexanolactone, β-heptanolactone, γ-heptanolactone, δ-heptanolactone, ε-heptanolactone, γ-octanolactone, δ-octanolactone, ε-octanolactone, δ - List cyclic esters (lactones) such as nonalactone, ε-nonalactone, ε-decanolactone, etc., as well as compounds in which the hydrogen of the methylene group adjacent to their carbonyl group is substituted with an alkyl group having 1 to 4 carbon atoms. I can do it.

Examples of the nitrogen-containing solvent include acyclic amides and cyclic amides. Examples of non-cyclic amides include alkoxyalkylamides.

Examples of the alkoxyalkylamides include 3-methoxy-N,N-dimethylpropionamide, 3-methoxy-N,N-diethylpropionamide, 3-methoxy-N,N-methylethylpropionamide, and 3-ethoxy-N,N-dimethylpropionamide. N,N-dimethylpropionamide, 3-ethoxy-N,N-diethylpropionamide, 3-ethoxy-N,N-methylethylpropionamide, 3-n-butoxy-N,N-dimethylpropionamide, 3-n -Butoxy-N,N-diethylpropionamide, 3-n-butoxy-N,N-methylethylpropionamide, 3-n-propoxy-N,N-dimethylpropionamide, 3-n-propoxy-N,N- Diethylpropionamide, 3-n-propoxy-N,N-methylethylpropionamide, 3-iso-propoxy-N,N-dimethylpropionamide, 3-iso-propoxy-N,N-diethylpropionamide, 3-iso -Propoxy-N,N-methylethylpropionamide, 3-tert-butoxy-N,N-dimethylpropionamide, 3-tert-butoxy-N,N-diethylpropionamide, 3-tert-butoxy-N,N- Examples include methylethylpropionamide and the like.

Moreover, it is also preferable to use alkoxyalkylamides, which are compounds represented by the following general formula (1), as the acyclic amides.

R ¹ -O-CH ₂ CH ₂ -(C=O)-NR ² R ³ ...(1)

In the above formula (1), R ¹ represents an alkyl group having 1 to 4 carbon atoms, and R ² and R ³ each independently represent a methyl group or an ethyl group. "Alkyl group having 1 to 4 carbon atoms" can be a linear or branched alkyl group, for example, methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group. , sec-butyl group, iso-butyl group, and tert-butyl group. The compounds represented by the above formula (1) may be used alone or in combination of two or more.

Examples of the cyclic amides include lactams, such as 2-pyrrolidone, 1-methyl-2-pyrrolidone, 1-ethyl-2-pyrrolidone, 1-propyl-2-pyrrolidone, 1-butyl-2-pyrrolidone, Examples include pyrrolidones such as. These are preferred in terms of promoting the formation of a film on resin particles, which will be described later, and 2-pyrrolidone is particularly preferred.

The alkylene glycol ethers may be alkylene glycol monoethers or diethers, and alkyl ethers are preferred. Specific examples include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, and triethylene glycol. Monoethyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether , dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monobutyl ether, alkylene glycol monoalkyl ethers, ethylene glycol dimethyl ether, ethylene glycol diethyl Ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, diethylene glycol methyl ethyl ether, diethylene glycol methyl butyl ether, triethylene glycol dimethyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, triethylene glycol methyl butyl ether, Examples include alkylene glycol dialkyl ethers such as tetraethylene glycol dimethyl ether, tetraethylene glycol diethyl ether, tetraethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, and tripropylene glycol dimethyl ether. It will be done.

The alkylene glycol constituting the alkylene glycol ethers preferably has 2 to 8 carbon atoms, more preferably 2 to 6 carbon atoms, even more preferably 2 to 4 carbon atoms, and particularly preferably 2 or 3 carbon atoms. The alkylene glycol constituting the alkylene glycol ethers may be one in which hydroxyl groups are condensed between alkylene glycol molecules. The number of condensations of alkylene glycol is preferably 1 to 4, more preferably 1 to 3, and even more preferably 2 or 3.

The ether constituting the alkylene glycol ethers is preferably an alkyl ether, preferably an alkyl ether having 1 to 4 carbon atoms, and more preferably an alkyl ether having 2 to 4 carbon atoms.

Alkylene glycol ethers are preferable because they have excellent permeability and excellent wettability of the ink on the recording medium, resulting in excellent image quality. In this respect, monoethers are particularly preferred.

Examples of polyhydric alcohols include 1,2-alkanediol (for example, ethylene glycol, propylene glycol (also known as propane-1,2-diol), 1,2-butanediol, 1,2-pentanediol, 1,2- alkanediols such as hexanediol, 1,2-heptanediol, and 1,2-octanediol), polyhydric alcohols (polyols) other than 1,2-alkanediol (e.g., ethylene glycol, propylene glycol, diethylene glycol, Propylene glycol, 1,3-propanediol, 1,3-butanediol (also known as 1,3-butylene glycol), 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2- Ethyl-2-methyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-methyl-1,3-propanediol, 2,2-dimethyl-1,3-propane Diol, 3-methyl-1,3-butanediol, 2-ethyl-1,3-hexanediol, 3-methyl-1,5-pentanediol, 2-methylpentane-2,4-diol, trimethylolpropane, glycerin, etc.).

Polyhydric alcohols can be divided into alkanediols and polyols.

Alkanediols are alkane diols having 5 or more carbon atoms. The alkane preferably has 5 to 15 carbon atoms, more preferably 6 to 10 carbon atoms, and still more preferably 6 to 8 carbon atoms. Preferably it is a 1,2-alkanediol.

The polyols are either polyols of alkanes having 4 or less carbon atoms or intermolecular condensates of hydroxyl groups of polyols of alkanes having 4 or less carbon atoms. The number of carbon atoms in the alkane is preferably 2 to 3. The number of hydroxyl groups in the molecule of the polyol is 2 or more, preferably 5 or less, and more preferably 3 or less. When the polyol is the above-mentioned intermolecular condensation product, the number of intermolecular condensations is 2 or more, preferably 4 or less, and more preferably 3 or less. Polyhydric alcohols can be used alone or in combination of two or more.

Alkanediols and polyols can primarily function as penetrating and/or humectant solvents. However, alkanediols tend to have strong properties as penetrating solvents, and polyols tend to have strong properties as moisturizing solvents.

Alkanediols are preferable because they have strong properties as penetrating solvents and have excellent wettability of the ink on the recording medium, resulting in excellent spread of the ink and excellent image quality.

Polyols have particularly high hydrophilicity, can particularly improve moisture retention, and have particularly excellent clogging resistance. In particular, by using polyols with a standard boiling point of 280.0° C. or lower, drying properties are good and the fastness of the recorded material is also good.

For the treatment liquid, one of the organic solvents listed above may be used alone, or two or more of them may be used in combination. In the case of two or more types of organic solvents, the content of organic solvents is the total content of them.

The content of the organic solvent in the treatment liquid is preferably 2.0% by mass or more based on the total amount of the treatment liquid. Further, it is preferably 40.0% by mass or less. Further, it is preferably 5.0 to 30.0% by mass, more preferably 10.0 to 25.0% by mass.

Further, the organic solvent preferably has a standard boiling point of 160 to 280°C. The treatment liquid preferably does not contain more than 2.0% by mass, and more preferably does not contain more than 1.0% by mass of substances with a standard boiling point exceeding 280°C based on the total amount of the treatment liquid. It is more preferable that the content does not exceed 0.5% by mass, and the content may be 0.0% by mass.

(surfactant)
The treatment liquid may contain a surfactant. The surfactant has a function of lowering the surface tension of the processing liquid and improving wettability with the recording medium and the substrate. Among the surfactants, acetylene glycol surfactants, silicone surfactants, and fluorine surfactants can be preferably used.

Examples of the acetylene glycol surfactant include, but are not limited to, Surfynol 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 product names, manufactured by Air Products & Chemicals), 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 product names, manufactured by Nissin Chemical Industry Co., Ltd.), acetylenol E00, E00P, E40, E100 (all product names, Kawa (manufactured by Ken Fine Chemical Co., Ltd.).

The silicone surfactant is not particularly limited, but polysiloxane compounds are preferred. The polysiloxane compound is not particularly limited, but includes, for example, polyether-modified organosiloxane. Commercially available polyether-modified organosiloxanes include, for example, BYK-306, BYK-307, BYK-333, BYK-341, BYK-345, BYK-346, BYK-348 (trade name: BYK-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, and KF-6017 (all trade names, manufactured by Shin-Etsu Chemical Co., Ltd.).

As the fluorine-based surfactant, it is preferable to use a fluorine-modified polymer, and specific examples include BYK-3440 (trade name, manufactured by BYK-Chemie Japan Co., Ltd.), Surflon S-241, S-242, S-243 (and above). (trade name, manufactured by AGC Seimi Chemical Co., Ltd.), Ftergent 215M (trade name, manufactured by Neos Corporation), and the like.

When the treatment liquid contains a surfactant, a plurality of surfactants may be contained. When the water-based ink composition contains a surfactant, the content is preferably 0.1% by mass or more and 2.0% by mass or less, more preferably 0.2% by mass or more and 1.5% by mass, based on the total mass. It is not more than 0.3% by mass and not more than 1.0% by mass.

The compounds exemplified here as surfactants are treated as not being the above-mentioned organic solvents.

(pH adjuster)
The treatment liquid of this embodiment may contain a pH adjuster. By containing the pH adjuster, for example, elution of impurities from the members forming the ink flow path can be suppressed or promoted, and the cleanability of the ink flow path can be adjusted. Examples of the pH adjuster include ureas, amines, morpholines, piperazines, and amino alcohols such as triethanolamine. Examples of ureas include urea, ethyleneurea, tetramethylurea, thiourea, 1,3-dimethyl-2-imidazolidinone, etc., and betaines (trimethylglycine, triethylglycine, tripropylglycine, triisopropylglycine, N , N,N-trimethylalanine, N,N,N-triethylalanine, N,N,N-triisopropylalanine, N,N,N-trimethylmethylalanine, carnitine, acetylcarnitine, etc.). Examples of amines include diethanolamine, triethanolamine, triisopropanolamine, and the like.

The compounds exemplified here as pH adjusters are treated as not being the above-mentioned organic solvents. For example, triethanolamine is a liquid at room temperature and has a standard boiling point of about 208°C, but it is not treated as the above-mentioned organic solvent.

(Fungicide, preservative)
The treatment liquid of this embodiment may contain a preservative.

By containing a preservative, the growth of mold and bacteria can be suppressed, and the storage stability of the treatment liquid becomes better. This makes it easier to use the processing liquid as a maintenance liquid when maintaining the printer without using it for a long period of time, for example. Preferred examples of preservatives include Proxel CRL, Proxel BDN, Proxel GXL, Proxel XL-2, Proxel IB, and Proxel TN.

(others)
The treatment liquid may further contain various additives such as a chelating agent, a rust preventive agent, a fungicide, an antioxidant, a reduction inhibitor, an evaporation accelerator, and a water-soluble resin, as necessary.

Examples of the chelating agent include ethylenediaminetetraacetate (EDTA), nitrilotriacetate, hexametaphosphate, pyrophosphate, and metaphosphate of ethylenediamine.

1.2.2. Method for manufacturing treatment liquid, physical properties, and method for adhering to recording medium The treatment liquid used in the recording method of this embodiment has a surface tension at 25°C from the viewpoint of appropriate wetting and spreading properties on the recording medium. It is preferably 40 mN/m or less, preferably 38 mN/m or less, more preferably 35 mN/m or less, even more preferably 30 mN/m or less. The surface tension was measured using an automatic surface tension meter CBVP-Z (manufactured by Kyowa Kaimen Kagaku Co., Ltd.) by checking the surface tension when a platinum plate was wetted with the composition in an environment of 25°C. can do.

Methods for attaching the processing liquid to the recording medium include an inkjet method, a coating method, a method of applying the processing liquid to the recording medium using various sprays, a method of applying the recording medium by immersing the recording medium in the processing liquid, and a method of applying the processing liquid to the recording medium. Either a non-contact method or a contact method, such as a method of applying the agent to the recording medium with a brush or the like, or a combination thereof can be used.

More preferably, the treatment liquid is applied to the recording medium by an inkjet method. In that case, the viscosity at 20°C is preferably 1.5 mPa·s or more and 15 mPa·s or less, more preferably 1.5 mPa·s or more and 7 mPa·s or less, and 1.5 mPa·s or more. More preferably, it is 5.5 mPa·s or less. When the treatment liquid is applied to the recording medium by an inkjet method, it is easy to efficiently form a predetermined treatment liquid attachment area on the recording medium.

The method for producing the treatment liquid of this embodiment is not particularly limited, but it can be produced by, for example, mixing the above-mentioned components in any order and removing impurities by filtering or the like as necessary. . As a method of mixing each component, a method of sequentially adding the materials to a container equipped with a stirring device such as a mechanical stirrer or a magnetic stirrer and stirring and mixing is preferably used.

1.3. Ink Adhesion Step The inkjet recording method of the present embodiment includes an ink adhesion step in which an aqueous ink composition containing a coloring material is ejected from an inkjet head to adhere to a recording medium. The ink adhesion step is performed on the recording medium that is supported and heated by the recording medium support section. Then, in the ink adhesion step, the recording medium is heated to a maximum temperature of 28.0° C. or more and 45.0° C. or less on the surface of the recording medium supported by the recording medium support portion and located at a position facing the inkjet head. The recording medium support section (platen) will be described later.

1.3.1. Water-based ink composition The water-based ink composition is an ink composition that is the above-mentioned water-based composition. The water-based ink composition includes a coloring material.

1.3.1.1. Coloring material The water-based ink composition includes a coloring material. As the coloring material, both pigments and dyes can be used, including carbon black, inorganic pigments including titanium white, organic pigments, oil-soluble dyes, acid dyes, direct dyes, reactive dyes, basic dyes, disperse dyes, Sublimation dyes and the like can be used. In the aqueous ink composition of this embodiment, the coloring material may be dispersed by a dispersion resin.

As the inorganic pigment, carbon blacks (C.I. Pigment Black 7) such as furnace black, lamp black, acetylene black, and channel black, iron oxide, titanium oxide, zinc oxide, silica, and the like can be used.

Examples of organic pigments include quinacridone pigments, quinacridonequinone pigments, dioxazine pigments, phthalocyanine pigments, anthrapyrimidine pigments, anthanthrone pigments, indanthrone pigments, flavanthrone pigments, perylene pigments, and diketopyrrolo Examples include pyrrole pigments, perinone pigments, quinophthalone pigments, anthraquinone pigments, thioindigo pigments, benzimidazolone pigments, isoindolinone pigments, azomethine pigments, and azo pigments.

Specific examples of organic pigments used in water-based ink compositions include the following.

As the cyan pigment, C. I. Pigment Blue 1, 2, 3, 15:3, 15:4, 15:34, 16, 22, 60, etc.; C.I. I. Examples include Bat Blue 4 and 60, and preferably C.I. I. Examples include one or a mixture of two or more selected from the group consisting of Pigment Blue 15:3, 15:4, and 60.

As a magenta pigment, C. I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57:1, 112, 122, 123, 168, 184, 202, C.I. I. Pigment Violet 19 and the like, preferably C.I. I. Pigment Red 122, 202, and 209, C.I. I. Examples include one or a mixture of two or more selected from the group consisting of Pigment Violet 19, or a solid solution.

As a yellow pigment, C. I. Pigment Yellow 1, 2, 3, 12, 13, 14C, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 119, 110, 114, 128, 129, 138, 150, 151, 154, 155, 180, 185, etc., preferably C. I. Examples include one or a mixture of two or more selected from the group consisting of Pigment Yellow 74, 109, 110, 128, and 138.

Pigments of other colors can also be used. Examples include orange pigments and green pigments.

The pigments exemplified above are examples of suitable pigments, and the present invention is not limited thereto. These pigments may be used alone or as a mixture of two or more, or may be used in combination with dyes.

Furthermore, the pigment may be dispersed using a dispersant selected from water-soluble resins, water-dispersible resins, surfactants, etc., or the surface of the pigment may be coated with ozone, hypochlorous acid, fuming sulfuric acid, etc. It may be oxidized or sulfonated and used as a self-dispersing pigment.

In the ink of this embodiment, when the pigment is dispersed with a dispersion resin, the ratio of the pigment to the dispersion resin is preferably 10:1 to 1:10, more preferably 4:1 to 1:3. Further, the volume average particle diameter of the pigment during dispersion is such that the maximum particle diameter is less than 500 nm and the average particle diameter is 300 nm or less, more preferably the volume average particle diameter is 200 nm or less when measured by a dynamic light scattering method. be.

Examples of dyes that can be used in the water-based ink composition include acid dyes, direct dyes, reactive dyes, and basic dyes as water-soluble systems, and disperse dyes, oil-soluble dyes, sublimation dyes, etc. as water-dispersed systems. .

The dyes exemplified above are examples of suitable coloring materials, and the present invention is not limited thereto. These dyes may be used alone or as a mixture of two or more, or may be used in combination with pigments.

The content of the coloring material can be adjusted as appropriate depending on the application, but is preferably 0.10% by mass or more and 20.0% by mass or less, more preferably 0.20% by mass or more and 15.0% by mass. or less, and more preferably 1.0% by mass or more and 10.0% by mass or less.

When a pigment is used as a coloring material, the volume average particle diameter of the pigment particles is preferably 10.0 nm or more and 200.0 nm or less, more preferably 30.0 nm or more and 200.0 nm or less, and 50.0 nm or more and 150.0 nm or less. It is more preferable, and particularly preferably 70.0 nm or more and 120.0 nm or less.

1.3.1.2. Other components Water-based ink compositions include, in addition to coloring materials, resin particles, wax, organic solvents, surfactants, additives, preservatives/fungicides, rust preventives, and chelating agents, as long as they do not impair functionality. , a viscosity modifier, an antioxidant, a fungicide, and other components may be contained.

(resin particles)
The water-based ink composition according to this embodiment may contain resin particles. The resin particles have a function as a so-called fixing resin that improves the adhesion and scratch resistance of the components of the aqueous ink composition attached to the recording medium.

Examples of such resin particles include urethane resins, acrylic resins, ester resins, fluorene resins, polyolefin resins, rosin modified resins, terpene resins, polyester resins, polyamide resins, epoxy resins, Examples include resin particles made of vinyl chloride resin, ethylene vinyl acetate resin, and the like. These resin particles are often handled in the form of an emulsion, but may also be in the form of a powder. Furthermore, the resin particles can be used alone or in combination of two or more.

Urethane resin is a general term for resins having urethane bonds. In addition to urethane bonds, urethane resins include polyether-type urethane resins containing ether bonds in the main chain, polyester-type urethane resins containing ester bonds in the main chain, polycarbonate-type urethane resins containing carbonate bonds in the main chain, etc. You may. As the urethane resin, commercially available products may be used, such as Superflex 210, 460, 460s, 840, E-4000 (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Rezamin D-1060, D-2020. , D-4080, D-4200, D-6300, D-6455 (product name, manufactured by Dainichiseika Industries Co., Ltd.), Takerac WS-6020, WS-6021, W-512-A-6 (product name, manufactured by Mitsui Chemicals Co., Ltd.) It may be selected from among commercially available products such as Kagaku Polyurethane Co., Ltd.), SunCure 2710 (trade name, manufactured by LUBRIZOL), and Permarin UA-150 (trade name, manufactured by Sanyo Chemical Industries, Ltd.).

Acrylic resin is a general term for polymers obtained by polymerizing at least acrylic monomers such as (meth)acrylic acid and (meth)acrylic ester as one component. Examples include the resulting resins and copolymers of acrylic monomers and other monomers. Examples include acrylic-vinyl resins that are copolymers of acrylic monomers and vinyl monomers. Further examples include copolymers with vinyl monomers such as styrene. Acrylamide, acrylonitrile, etc. can also be used as the acrylic monomer.

Commercially available products may be used for the resin emulsion made from acrylic resin, such as FK-854, Movinyl 952B, 718A (trade name, manufactured by Japan Coating Resin Co., Ltd.), Nipol LX852, LX874 (trade name, manufactured by Nippon Zeon Co., Ltd.). ), Polysol AT860 (trade name, manufactured by Showa Denko K.K.), Boncourt AN-1190S, YG-651, AC-501, AN-1170, 4001 (trade name, manufactured by DIC Corporation), etc. You can.

Note that in this specification, the acrylic resin may be a styrene acrylic resin as described above. Moreover, in this specification, the notation "(meth)acrylic" means at least one of acrylic and methacryl.

Styrene acrylic resin is a copolymer obtained from styrene monomer and acrylic monomer, and includes styrene-acrylic acid copolymer, styrene-methacrylic acid copolymer, styrene-α-methylstyrene-acrylic and acid copolymers. Commercially available styrene acrylic resins may be used, such as Joncryl 62J, 7100, 390, 711, 511, 7001, 632, 741, 450, 840, 74J, HRC-1645J, 734, 852, 7600. , 775, 537J, 1535, PDX-7630A, 352J, 352D, PDX-7145, 538J, 7640, 7641, 631, 790, 780, 7610 (product name, manufactured by BASF), Movinyl 966A, 975N (product name, Japan (manufactured by Coating Resin Co., Ltd.).

The vinyl chloride resin may be a vinyl chloride-vinyl acetate copolymer. Examples of the ester resin include polymers containing acrylic ester as a monomer, such as styrene-methacrylic acid-acrylic ester copolymer, styrene-α-methylstyrene-acrylic acid copolymer, Examples include styrene-α-methylstyrene-acrylic acid-acrylic acid ester copolymer.

The polyolefin resin has an olefin such as ethylene, propylene, butylene in its structural skeleton, and known resins can be appropriately selected and used. As the olefin resin, commercially available products may be used, such as Arrowbase CB-1200, CD-1200 (trade name, manufactured by Unitika Co., Ltd.), and the like.

The resin particles may be supplied in the form of an emulsion, and examples of commercially available resin emulsions include Microgel E-1002, E-5002 (trade name, Nippon Paint Co., Ltd., styrene acrylic resin emulsion). ), Boncourt AN-1190S, YG-651, AC-501, AN-1170, 4001, 5454 (product name, manufactured by DIC, styrene acrylic resin emulsion), Polysol AM-710, AM-920, AM-2300, AP-4735, AT-860, PSASE-4210E (acrylic resin emulsion), Polysol AP-7020 (styrene acrylic resin emulsion), Polysol SH-502 (vinyl acetate resin emulsion), Polysol AD-13, AD-2, AD-10, AD-96, AD-17, AD-70 (ethylene/vinyl acetate resin emulsion), Polysol PSASE-6010 (ethylene/vinyl acetate resin emulsion) (all trade names, manufactured by Showa Denko), Polysol SAE1014 ( Product name, Nippon Zeon Co., Ltd., styrene-acrylic resin emulsion), Cybinol SK-200 (product name, Saiden Chemical Co., Ltd., acrylic resin emulsion), AE-120A (product name, JSR Co., Ltd., acrylic resin emulsion) ), AE373D (trade name, manufactured by E-TEC Co., Ltd., carboxy-modified styrene acrylic resin emulsion), Seikadyne 1900W (trade name, manufactured by Dainichiseika Industries, Ltd., ethylene/vinyl acetate resin emulsion), Vinibran 2682 (acrylic resin emulsion), Vinibran 2886 (vinyl acetate/acrylic resin emulsion), Viniblan 5202 (acetic acid acrylic resin emulsion) (trade name, manufactured by Nissin Chemical Industry Co., Ltd.), Viniblan 700, 2586 (trade name, manufactured by Nissin Chemical Industry Co., Ltd.), Elitel KA -5071S, KT-8803, KT-9204, KT-8701, KT-8904, KT-0507 (product name, manufactured by Unitika, polyester resin emulsion), Hitech SN-2002 (product name, manufactured by Toho Chemical Co., Ltd., polyester resin) Emulsion), Takelac W-6020, W-635, W-6061, W-605, W-635, W-6021 (product name, manufactured by Mitsui Chemicals Polyurethane Co., Ltd., urethane resin emulsion), Superflex 870, 800, 150 , 420, 460, 470, 610, 620, 700 (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., urethane resin emulsion), Permarin UA-150 (trade name, manufactured by Sanyo Chemical Industries, Ltd., urethane resin emulsion), SunCure 2710 (product name, manufactured by Nippon Lubrizol Co., Ltd., urethane resin emulsion), NeoRez R-9660, R-9637, R-940 (product name, manufactured by Kusumoto Kasei Co., Ltd., urethane resin emulsion), Adekabon Titer HUX-380, 290K (product name, manufactured by ADEKA Co., Ltd., urethane resin emulsion), Movinyl 966A, Movinyl 7320 (product name, manufactured by Japan Coating Resin Co., Ltd.), Joncryl 7100, 390, 711, 511, 7001, 632, 741, 450, 840, 74J, HRC-1645J, 734, 852, 7600, 775, 537J, 1535, PDX-7630A, 352J, 352D, PDX-7145, 538J, 7640, 7641, 631, 790, 780, 7610 ( The above product names, manufactured by BASF Corporation), NK Binder R-5HN (product name, manufactured by Shin-Nakamura Chemical Co., Ltd.), Hydran WLS-210 (product name, manufactured by DIC Corporation, non-crosslinking polyurethane), Joncryl 7610 (product name, manufactured by DIC Corporation), It may be used by selecting from among the product names (trade names, manufactured by BASF), etc.

Among these, the material for the resin particles is preferably selected from urethane resins, acrylic resins, ester resins, and vinyl chloride resins in terms of better adhesion and abrasion resistance. Furthermore, it is preferable that resin particles of urethane resin or acrylic resin are included as the resin particles, since this can further improve the adhesion and scratch resistance of the components of the aqueous ink composition adhered to the recording medium.

When adding resin particles to the water-based ink composition, the content thereof is 0.1% by mass or more and 20% by mass or less, preferably 0.5% by mass as solid content, based on the total mass of the water-based ink composition. It is 15.0% by mass or less, more preferably 1.0% by mass or more and 15.0% by mass or less, and even more preferably 2.0% by mass or more and 10.0% by mass or less.

(wax)
The aqueous ink composition of this embodiment may contain wax. Examples of waxes include plant/animal waxes such as carnauba wax, candeli wax, beeswax, rice wax, and lanolin; petroleum waxes such as paraffin wax, microcrystalline wax, polyethylene wax, oxidized polyethylene wax, polypropylene wax, and petrolatum; Mineral waxes such as montan wax and ozokerite; carbon waxes, Hoechst waxes, polyolefin waxes, synthetic waxes such as stearic acid amide, natural and synthetic waxes such as α-olefin/maleic anhydride copolymers, emulsions and blended waxes, etc. They can be used alone or in combination. Among these, polyolefin waxes (especially polyethylene waxes and polypropylene waxes) are preferably used from the viewpoint of being more effective in increasing the abrasion resistance of images.

As the wax, commercially available products can be used as they are, such as Nopcote PEM-17 (trade name, manufactured by San Nopco Co., Ltd.), Chemipearl W4005 (trade name, manufactured by Mitsui Chemicals Co., Ltd.), AQUACER515, 539, 593 (products listed above). (manufactured by BIC Chemie Japan Co., Ltd.), etc.

In the heating step in the recording method, the melting point of the wax is preferably 100.0°C or more and 180.0°C or less, more preferably 105. The temperature is 0°C or more and 140°C or less, more preferably 110.0°C or more and 135.0°C or less.

The wax may be supplied in the form of an emulsion or suspension. The wax content is 0.05% by mass or more and 5.0% by mass or less, more preferably 0.1% by mass or more and 5.0% by mass or less in terms of solid content, based on the total mass of the aqueous ink composition. More preferably, it is 0.1% by mass or more and 2.0% by mass or less. When the wax content is within the above range, the recorded image can exhibit excellent scratch resistance.

(others)
Water, organic solvents, surfactants, additives, preservatives/fungicides, rust preventives, chelating agents, viscosity modifiers, antioxidants, antifungal agents, etc. that can be used in water-based ink compositions include: It is the same as the treatment liquid described above, and the description of "treatment liquid" in the explanation of "1.2.1.2. Other components" will be replaced with "aqueous ink composition" and the explanation will be omitted.

Regarding the organic solvent that may be contained in the aqueous ink composition, those with a standard boiling point of 280.0°C or lower are preferable, those with a normal boiling point of 150.0°C or higher and 280.0°C or lower are more preferable, and those with a normal boiling point of 170.0°C or higher and 280°C or lower are preferable. .0°C or lower is even more preferred, 180.0°C or higher and 280.0°C or lower, even more preferably 190.0°C or higher and 270.0°C or lower, and 200.0°C or higher and 250.0°C or higher. Particularly preferred is a temperature below 0°C.

Further, the aqueous ink composition contains an organic solvent having a standard boiling point of 180.0°C or more and 280.0% or less, preferably 25.0% or more and 30.0% by mass or less, and preferably 25.0% or more and 30.0% by mass. % or less is more preferable.

Further, the content of the organic solvent with a standard boiling point exceeding 280.0°C is preferably 2.0% by mass or less, more preferably 1.5% by mass or less, and still more preferably 1.0% by mass or less, based on the total amount of the water-based ink composition. 0.0% by mass or less (not exceeding this), and may even not be contained, that is, 0.0% by mass. As a result, the drying properties of the treatment liquid applied to the recording medium can be improved, and the adhesion to the recording medium can be improved.

Note that examples of the organic solvent having a standard boiling point of more than 280.0°C include glycerin, polyethylene glycol monomethyl ether, and the like.

1.3.2. Physical Properties of Water-Based Ink Composition The water-based ink composition is deposited onto a recording medium by an inkjet method (ink deposition step). Therefore, the viscosity of the aqueous ink composition at 20° C. is preferably 1.5 mPa·s or more and 15.0 mPa·s or less, more preferably 1.5 mPa·s or more and 7.0 mPa·s or less. , more preferably 1.5 mPa·s or more and 5.5 mPa·s or less. Since the aqueous ink composition is ejected from an inkjet head and attached to the recording medium, it is easy to efficiently form a predetermined image on the recording medium.

The aqueous ink composition used in the inkjet recording method of this embodiment has a surface tension of 40.0 mN/m or less at 25.0° C., preferably 40.0 mN/m or less, from the viewpoint of appropriate wetting and spreading properties on the recording medium. It is preferably 38.0 mN/m or less, more preferably 35.0 mN/m or less, even more preferably 30.0 mN/m or less.

1.3.3. Method for manufacturing water-based ink composition The method for manufacturing the water-based ink composition of the present embodiment is not particularly limited, but for example, the above-mentioned ink components may be mixed in any order and filtered as necessary to remove impurities. It can be manufactured by removing. As a method of mixing each component, a method of sequentially adding the materials to a container equipped with a stirring device such as a mechanical stirrer or a magnetic stirrer and stirring and mixing is preferably used.

1.3.4. Cohesive property of ink composition The water-based ink composition has the above-mentioned absorbance B at the maximum peak wavelength in the range of 380.0 nm or more and 680 nm or less of a mixed liquid in which 0.1% by mass of the water-based ink composition is mixed with pure water. The ratio (A/B) of the absorbance A at the wavelength of a mixed liquid obtained by mixing 0.1% by mass of the water-based ink composition with respect to the treatment liquid is adjusted to be 0.5 or more and 0.95 or less. Ru.

By setting the ratio (A/B) to 0.5 or more and 0.95 or less, especially 0.5 or more, even when the treatment liquid mist comes into contact with the aqueous ink composition near the nozzle, the degree of aggregation of the components can be reduced. can be suppressed. This suppresses clogging of the nozzle, and even if clogging occurs, recovery from clogging can be improved.

Further, when the ratio (A/B) is 0.95 or less, the ink has sufficient reactivity when it comes into contact with the treatment liquid, and excellent image quality can be obtained.

On the other hand, when the ratio (A/B) is 0.5 or more and 0.95 or less, especially 0.5 or more, the reactivity when it comes into contact with the processing liquid becomes gentle, so when forming an image, The agglomeration rate of the components may be reduced. In this case, when the treatment liquid and the aqueous ink composition are mixed on the recording medium, the drying speed of the mixture comes to affect the aggregation speed of the image. In this embodiment, the ink adhesion process is performed on a recording medium that is heated and supported by a recording medium support section (platen), so the aggregation speed may change depending on the amount of heat that the recording medium receives from the platen.

For example, when the recording medium passes over the platen, if the platen is uneven, the drying speed of the portion of the image that has passed through the convex portion of the platen will be different from that of the portion that has passed through the concave portion of the platen. Even if the same image is formed, the degree of aggregation will be different, resulting in a difference in color development. Such a difference in color development is sometimes referred to as "in-plane color difference" in this specification. The inventor's studies have revealed that the in-plane color difference becomes particularly noticeable when a large-sized inkjet recording device is used. A large-sized inkjet recording device refers to a device having a width of 0.5 m or more in a direction perpendicular to the conveying direction of the recording medium.

The width in the direction perpendicular to the conveying direction of the recording medium (width in the width direction) is preferably 0.5 m or more, more preferably 1.0 m or more, and even more preferably 1.5 m or more. Although the upper limit is not limited, it is preferably 5.0 m or less.

Furthermore, the in-plane color difference increases as the temperature variation within the printed surface increases. The way the coloring materials mix differs between when the ink is mixed when the temperature is low and dot drying has not progressed, and when the ink is mixed when the temperature is high and the water evaporates and the ink has thickened. This is thought to be due to the fact that the color appears to change.

As a case where the support surface that supports the recording medium is not flat, there are cases where the support surface of the platen has unevenness. In this case, the support surface comes into contact with the recording medium at the convex portion, and the heating from the platen becomes stronger at the convex portion, increasing the temperature of the recording medium. On the other hand, since the concave portion of the support surface does not come into contact with the recording medium, the heating from the platen becomes weaker in this portion, and the temperature of the recording medium decreases. In particular, in the recessed portion, the distance between the platen and the recording medium may not be constant, and the temperature of the recording medium may vary greatly depending on the location.

Then, the temperature variation becomes large between the portion of the recording medium that passes through the convex portion and the portion that passes through the concave portion. This causes in-plane color difference.

An example of a case where the support surface of the platen has irregularities is when the support surface has irregularities that intermittently support the recording medium. Note that the unevenness for intermittently supporting the recording medium may also be referred to as ribs. Examples of the support surface having ribs include the one shown in FIG. 1 of JP-A No. 2009-234105.

In the inkjet recording method of this embodiment, since the recording medium support part has a flat support surface that supports the recording medium, the ratio (A/B) of the aqueous ink composition is 0.5 or more and 0.95 or less. Even if there is, the in-plane color difference can be kept sufficiently small.

Here, examples of the "flat" support surface for supporting the recording medium of the recording medium support section include a support surface that does not have irregularities for intermittently supporting the recording medium. . The support surface used in this embodiment is, for example, a support surface without ribs.

The support surface is an area that accounts for 90.0% or more of the area of the part that supports the recording medium during recording by the support surface and faces the inkjet head (the part that discharges ink) during recording, Preferably, the support surface is in contact with the recording medium.

Alternatively, the support surface where the support surface contacts the recording medium over 90.0% or more of the area as described above may be a flat support surface. A flat support surface will be discussed further below.

The ratio (A/B) can be adjusted by adjusting the reactivity between the aqueous ink composition and the treatment liquid. The smaller the reactivity, the smaller the absorbance ratio (A/B). The reactivity may be adjusted by adjusting the reactivity of either the processing liquid or the ink.

The reactivity of the treatment liquid may be adjusted by adjusting the content and type of flocculant. The higher the content of flocculant, the higher the reactivity. What is necessary is to prepare treatment liquids of various flocculants, mix them with ink, measure the absorbance, grasp the absorbance of each flocculant, and select a flocculant having the desired reactivity.

The reactivity of the aqueous ink composition can be adjusted, for example, by the zeta potential. The larger the absolute value of the zeta potential, the higher the reactivity tends to be. In other words, the ratio (A/B) tends to increase.

The zeta potential can be adjusted, for example, by adjusting the acid value of a dispersion resin for dispersing the coloring material contained in the ink, or, if no dispersion resin is used, the acid value of the coloring material itself. Or, if the ink contains resin particles, if the resin particles are dispersed with an emulsifier, the acid value of the emulsifier used, or if the resin particles are dispersed without an emulsifier, the acid value of the resin of the resin particles. Adjustment can be made by adjusting the acid value.

The higher the acid value, the higher the absolute value of the zeta potential tends to be. In addition, when the zeta potential of the ink is set to a negative value, it is preferable because it is easy to adjust.

Note that the acid value here is a value measured according to JIS K 0070:1992, and is the amount (mg) of potassium hydroxide required to completely neutralize 1 g of resin.

The absorbance and ratio (A/B) can be measured, for example, as follows. The absorbance (B) of a liquid obtained by dropping 0.04 g of the water-based ink composition into 40 g of pure water and stirring is measured at the maximum peak wavelength in the range of 380.0 nm or more and 680 nm or less. The water-based ink composition was added dropwise to 40 g of the treatment liquid in the same proportion and stirred, and the absorbance (A) at the above wavelength was measured. Obtain the ratio (A/B). As the wavelength for absorbance (A), the maximum peak wavelength determined for absorbance (B) is used. Measure three times and take the average value. The absorbance can be measured, for example, with an ultraviolet-visible-near-infrared spectrophotometer V-700 manufactured by JASCO Corporation. Measurement is performed after stirring and standing still for 5 minutes. The measurement sample is taken from above the liquid level after it has come to rest.

The maximum peak wavelength is the wavelength at the top of a mountain-shaped spectrum, if any, in the spectroscopic spectrum analysis in the above wavelength range. If there are multiple mountain-shaped spectra in the above wavelength range, the peak wavelength has the highest absorbance. If there is no mountain-shaped spectrum in the above wavelength range, it is the wavelength at which the absorbance in the above wavelength range is maximum. In this case, the maximum peak wavelength is not a mountain-shaped spectrum. As described above, in this embodiment, the maximum peak wavelength is not limited to the mountain-shaped spectrum, but also includes the wavelength at which the absorbance is maximum in the above wavelength range. Note that depending on the color of the ink, there may be no mountain-shaped spectrum in the above wavelength range.

If the cohesive force of the coloring material against the coagulant is large, the aggregates are difficult to re-disperse even when stirred. According to the Beer-Lambert law, absorbance and pigment concentration are considered to be proportional, so it is considered that the smaller the absorbance (A), the lower the concentration of the pigment to be redispersed.

The ratio (A/B) is preferably 0.6 or more, more preferably 0.7 or more, and even more preferably 0.8 or more. When it is above the above range, clogging recovery properties are better and preferred. On the other hand, the ratio is preferably 0.9 or less, more preferably 0.85 or less. When it is below the above range, image quality and in-plane color difference reduction are better and preferred.

1.3.5. Zeta Potential of Ink The reactivity of a water-based ink composition may be adjusted by the zeta potential as described above. For example, if the average zeta potential of the aqueous ink composition is -70.0 mV or more and -45.0 mV or less, preferably -65.0 mV or more and -50.0 mV or less, redispersibility and cohesiveness are balanced; It can be made into a good one. This makes it easy to keep the ratio A/B within the above range, which is preferable.

The average zeta potential of the ink can be adjusted to -70 mV or more and -50 mV or less, for example, as described above, but it is also preferable to use a coloring material, for example. When adjusting with a coloring material, it is possible to change the type of dispersant of the coloring material and adjust whether or not an anionic group is introduced into the dispersant and the amount of the anionic group introduced. The larger the amount introduced, the larger the absolute value on the negative side of the average zeta potential of the ink. This also corresponds to adjusting the acid value of the dispersant, and the larger the amount introduced, the higher the acid value.

Examples of the anionic group include a sulfonic acid group, a carboxyl group, a phosphoric acid group, and the like. More than one of these groups may be present. One method of introducing an anionic group into a dispersant is to use a monomer having these anionic groups as a monomer when polymerizing the dispersant, or to adjust the amount used. Examples of monomers having carboxyl groups include acrylic acid and methacrylic acid. Furthermore, an anionic reactive surfactant may be used when polymerizing the dispersant. A dispersant polymerized using this will contain the anionic reactive surfactant as a structural unit.

The dispersant can be synthesized by emulsion polymerization or suspension polymerization using addition polymerization monomers. Further, the anionic reactive surfactant may be an addition polymerizable monomer, or another monomer having an anionic water-soluble group may be used for polymerization.

Monomers used for polymerization include acrylic esters such as methyl acrylate and ethyl acrylate, methacrylic esters such as methyl methacrylate, ethyl methacrylate, and 2-ethylhexyl methacrylate, vinyl acetate, ethylene, propylene, isobutylene, and butadiene. Compounds having a carbon-carbon double bond such as , styrene, methylstyrene, styrene sulfonic acid and its salts, vinyl chloride, maleic anhydride, and divinylbenzene can be used.

Moreover, when using an anionic reactive surfactant in the dispersant of this embodiment, it is introduced by using the anionic reactive surfactant as a monomer. That is, the anionic reactive surfactant is a compound containing a carbon-carbon double bond, and may be incorporated into the constituent unit of the dispersant using such a double bond.

The average zeta potential of the water-based ink composition can be measured, for example, by diluting the water-based ink composition 1000 times with water and using Zetasizer Nano ZS (trade name, manufactured by Malvern Panalytical).

1.3.6. Inkjet Head In the ink adhesion step of the inkjet recording method of this embodiment, the above-mentioned water-based ink composition is ejected from the inkjet head to be applied to the recording medium.

Inkjet heads include, but are not particularly limited to, those that employ a recording method using a piezoelectric element, and those that record using thermal energy from a heater, etc. of a heat-generating resistor arranged in the inkjet head. However, any inkjet head can be used.

Further, the inkjet head used in the step of attaching the water-based ink composition to the recording medium may or may not be equipped with a circulation channel for circulating the water-based ink composition.

1.3.7. Variation of Ink Adhesion Step The ink adhesion step in the inkjet recording method of this embodiment may be performed by performing main scanning and sub-scanning on the recording medium multiple times.

In addition, in the ink adhesion step, the recording medium is heated to a maximum temperature of 28.0°C or more and 45.0°C or less on the surface of the recording medium supported by the recording medium support section and facing the inkjet head. The maximum temperature is more preferably 30.0°C or more and 40.0°C or less, and even more preferably 32.0°C or more and 38.0°C or less.

Furthermore, in the ink adhesion step, the temperature difference in the in-plane distribution of the surface temperature of the recording medium at a position supported by the recording medium support section and facing the inkjet head is 8.0 degrees Celsius or less, more preferably 6.0 degrees Celsius or less. The temperature is preferably 5.0°C or lower, more preferably 5.0°C or lower. The temperature difference can be adjusted by, for example, the shape of the recording medium support, the arrangement of the heat source, and the like. In this way, an image with smaller in-plane color difference can be formed.

Note that the surface temperature of the recording medium can be measured using, for example, an infrared sensor (IR sensor). In addition, the distribution of the surface temperature of the recording medium is, for example, under the recording conditions, the temperature is set at 20 locations at both ends in the width direction and at predetermined intervals on the recording surface side of the portion supported by the recording medium and facing the inkjet head. It can be evaluated by measuring.

Furthermore, the ink adhesion step may include a blowing step of blowing air onto the recording medium to which the aqueous ink composition has been adhered by a blowing mechanism. That is, the method may further include a step of moving air around the recording medium using a blowing mechanism. In this way, it is possible to further suppress the temperature difference in the in-plane surface temperature distribution of the recording medium when the recording medium is supported by the recording medium support portion and is located at a position facing the inkjet head.

Further, in this case, the air blowing mechanism used to move the air around the recording medium may send air at room temperature, warm air, or hot air. It is more preferable to use blowing air in combination with the secondary heating because the drying rate of the solvent component of the aqueous ink composition can be further increased. The speed of the air blown onto the recording medium in the air blowing step is preferably 0.5 m/sec or more, more preferably 1.0 m/sec or more, and even more preferably 1.5 m/sec or more. More preferably, the speed is 2.0 m/sec or more. In this case, the in-plane color difference reduction and image quality are better and preferred. On the other hand, the wind speed is preferably 5.0 m/sec or less, more preferably 4.0 m/sec or less, and even more preferably 3.0 m/sec or less. In this case, clogging recovery properties are better and preferred.

Further, the temperature of the air blown onto the recording medium in the air blowing step may be warm air or room temperature air. The air temperature is preferably 45.0°C or lower, more preferably 40.0°C or lower. Furthermore, the temperature is preferably 30°C or lower, and preferably 25°C or lower. In this case, the in-plane color difference reduction and image quality are better and preferred. On the other hand, the air temperature is preferably 20°C or higher, more preferably 23°C or higher, and even more preferably 25°C or higher. In this case, clogging recovery properties are better and preferred. The wind speed and temperature are assumed to be approximately at the position of the inkjet head upward from the recording surface of the recording medium.

2. Inkjet Recording Apparatus The inkjet recording apparatus according to this embodiment can perform the above-described inkjet recording method.

2.1. Overview of Inkjet Recording Apparatus An example of an inkjet recording apparatus suitable for the water-based ink composition according to the present embodiment will be described with reference to the drawings. In each of the drawings used in the following description, the scale and relative dimensions of each member are changed as appropriate in order to make each member a recognizable size.

FIG. 1 is a schematic cross-sectional view schematically showing an inkjet recording apparatus 1. As shown in FIG. FIG. 2 is a perspective view showing an example of the structure around the carriage of the inkjet recording apparatus 1 shown in FIG. As shown in FIGS. 1 and 2, the inkjet recording apparatus 1 includes an inkjet head 2, a heater 3, a platen heater 4, an afterheater 5, a fan 6, a preheater 7, a ventilation fan 8, and a carriage 9. , a platen 11, a carriage moving mechanism 13, a conveyance means 14, and a control unit CONT. The inkjet recording apparatus 1 has a heating mechanism including a platen 11 as a recording medium support part and a platen heater 4 that heats the platen 11. In the inkjet recording apparatus 1, the operation of the entire inkjet recording apparatus 1 is controlled by the control unit CONT shown in FIG. The platen 11 is an example of a recording medium support section, and the platen heater 4 is an example of a heating mechanism.

The inkjet head 2 is configured to perform recording on the recording medium M by ejecting a treatment liquid and a water-based ink composition from the nozzles of the inkjet head 2 and depositing the treatment liquid and the water-based ink composition. In this example, the inkjet head 2 is a serial type inkjet head, and scans in the main scanning direction relative to the recording medium M multiple times to deposit the ink and the water-based ink composition onto the recording medium M. The inkjet head 2 is mounted on a carriage 9 shown in FIG. The inkjet head 2 is scanned multiple times in the main scanning direction relative to the recording medium M by the operation of the carriage moving mechanism 13 that moves the carriage 9 in the width direction of the recording medium M. The medium width direction is the main scanning direction of the inkjet head 2. Scanning in the main scanning direction is also referred to as main scanning.

Moreover, here, the main scanning direction is the direction in which the carriage 9 carrying the inkjet head 2 moves. In FIG. 1, this is a direction that intersects with the sub-scanning direction, which is the conveyance direction of the recording medium M, as indicated by an arrow SS. In FIG. 2, the width direction of the recording medium M, that is, the direction represented by S1-S2 is the main scanning direction MS, and the direction represented by T1→T2 is the sub-scanning direction SS. Note that in one scan, scanning is performed in the main scanning direction, that is, in either direction of arrow S1 or arrow S2. Then, by repeating the main scan of the inkjet head 2 and the sub-scan, which is transport of the recording medium M, multiple times, recording is performed on the recording medium M. That is, the treatment liquid application process and the aqueous ink composition application process include multiple main scans in which the inkjet head 2 moves in the main scanning direction, and multiple times in which the recording medium M moves in the sub-scanning direction intersecting the main scanning direction. This is performed by sub-scanning.

The cartridge 12 that supplies the treatment liquid and the aqueous ink composition to the inkjet head 2 includes a plurality of independent cartridges. The cartridge 12 is removably attached to the carriage 9 on which the inkjet head 2 is mounted. Each of the plurality of cartridges is filled with a different type of water-based ink composition or processing liquid, and the water-based ink composition or processing liquid is supplied from the cartridge 12 to each nozzle. Although the cartridge 12 is shown as being mounted on the carriage 9, the present invention is not limited thereto, and the cartridge 12 may be provided at a location other than the carriage 9 and may be supplied to each nozzle through a supply pipe (not shown).

A conventionally known method can be used for ejection from the inkjet head 2. Here, a method is used in which droplets are ejected using the vibration of a piezoelectric element, that is, an ejection method is used in which ink droplets are formed by mechanical deformation of an electrostrictive element.

The inkjet recording apparatus 1 can include a drying mechanism that performs a drying process (primary heating) to dry the recording medium M when the aqueous ink composition is ejected from the inkjet head 2 and adheres to the recording medium. For drying, drying by heating or blowing air can be used. As the drying mechanism, a conduction type, an air blowing type, a radiation type, etc. can be used. In the conduction type, heat is conducted to the recording medium from a member that comes into contact with the recording medium. For example, the illustrated platen heater 4 may be used. The blowing type blows room temperature air or hot air to the recording medium to dry the water-based ink composition and the like. An example is the blower fan 8. The radiation type heats the recording medium by emitting radiation that generates heat to the recording medium. For example, the heater 3 may be configured as an after-heater and emit infrared rays. These drying mechanisms may be used alone or in combination.

When drying the recording medium M in the drying process (primary heating), the heater 3, ventilation fan 8, etc. can be used. Note that when the heater 3 is used, the recording medium M can be heated radially by infrared radiation from the inkjet head 2 side. As a result, although the inkjet head 2 is likely to be heated at the same time, the temperature can be increased without being affected by the thickness of the recording medium M, compared to a case where the inkjet head 2 is heated from the back side of the recording medium M using a platen heater 4 or the like. .

The inkjet recording apparatus 1 may include a ventilation fan 8 as a ventilation mechanism that blows air onto the recording medium M to which the aqueous ink composition is adhered in the ink adhesion process. The ventilation fan 8 can dry the processing liquid and water-based ink composition on the recording medium M by applying warm air or air at the same temperature as the environment to the recording medium M. When the ventilation fan 8 is provided, the speed of the air blown onto the recording medium is, for example, 1.0 m/sec or more, preferably 1.5 m/sec or more. Further, the temperature of the air blown onto the recording medium M is 45.0°C or less, preferably 40.0°C or less, and more preferably 35.0°C or less.

The platen heater 4 moves the recording medium M onto the platen at a position facing the inkjet head 2 so that the aqueous ink composition ejected by the inkjet head 2 can be dried quickly from the time it is attached to the recording medium M. 11. The platen heater 4 is capable of heating the recording medium M by conduction, is used in the above-mentioned inkjet recording method, and is controlled so that the surface temperature of the recording medium M is 28.0°C or more and 45.0°C or less. be done. Although not shown, in a line type ink jet recording apparatus, the platen heater 4 corresponds to an under heater.

Note that the upper limit of the surface temperature of the recording medium M during the drying process using the drying mechanism in the ink adhesion process is preferably 45.0°C or less, more preferably 40.0°C or less, and 38.0°C. It is even more preferable that it is below, and particularly preferably that it is below 35.0°C. Further, the lower limit of the surface temperature of the recording medium M is preferably 25.0°C or higher, more preferably 28.0°C or higher, even more preferably 30.0°C or higher, and even more preferably 32.0°C. It is especially more preferable that it is above. This can suppress drying and compositional fluctuations of the aqueous ink composition in the inkjet head 2, and suppress welding of the aqueous ink composition and resin to the inner wall of the inkjet head 2. Further, the water-based ink composition or water-based ink composition can be fixed on the recording medium M at an early stage, and set-off can be suppressed and image quality can be improved.

The inkjet recording apparatus 1 of this embodiment includes an after heater 5 as a heating means that can perform a heating process (secondary heating) in which the recording medium M is heated to dry and fix the ink after the ink adhesion process. You may prepare.

The after-heater 5 used in the post-heating process is a heater for drying and solidifying the aqueous ink composition attached to the recording medium M, that is, for secondary heating or secondary drying. The after-heater 5 can be used in the post-heating process. When the after-heater 5 heats the recording medium M on which an image is recorded, the water contained in the water-based ink composition evaporates and scatters more quickly, and the resin contained in the water-based ink composition forms an ink film. is formed. In this way, the ink film is firmly fixed or adhered onto the recording medium M, resulting in excellent film-forming properties, and an excellent high-quality image can be obtained in a short time.

The upper limit of the surface temperature of the recording medium M by the after-heater 5 is preferably 120.0°C or less, more preferably 100.0°C or less, and even more preferably 90.0°C or less. Further, the lower limit of the surface temperature of the recording medium M is preferably 60.0°C or higher, more preferably 70.0°C or higher, and even more preferably 80.0°C or higher. When the temperature is within the above range, high quality images can be obtained in a short time. In the line-type inkjet recording apparatus, the after-heater 5 corresponds to an after-heater and can be constituted by a carbon heater or the like.

The inkjet recording apparatus 1 may include a fan 6. The fan 6 is a blowing mechanism and can move air around the recording medium M. Applying cooling, additional drying, and additional heating to the aqueous ink composition recorded on the recording medium M by using the fan 6 after the heating step (infrared irradiation) or during the heating step. I can do it. Therefore, the gas blown from the fan 6 may be room temperature gas or warm air.

Further, the inkjet recording apparatus 1 may include a preheater 7 that preheats the recording medium M before the aqueous ink composition is attached to the recording medium M. Further, the inkjet recording apparatus 1 may include a ventilation fan 8 so that the water-based ink composition or water-based ink composition attached to the recording medium M can be dried more efficiently. Note that the preheater 7 may also be provided in a line type inkjet recording apparatus.

Below the carriage 9 are a platen 11 that supports the recording medium M, a carriage movement mechanism 13 that moves the carriage 9 relative to the recording medium M, and a roller that conveys the recording medium M in the sub-scanning direction. A conveyance means 14 is provided. The operations of the carriage moving mechanism 13 and the conveyance means 14 are controlled by a control unit CONT.

FIG. 3 is a functional block diagram of the inkjet recording apparatus 1. The control unit CONT is a control unit for controlling the inkjet recording apparatus 1. The interface unit 101 (I/F) is for transmitting and receiving data between the computer 130 (COMP) and the inkjet recording apparatus 1. The CPU 102 is an arithmetic processing unit for controlling the entire inkjet recording apparatus 1 . The memory 103 (MEM) is for securing an area for storing programs for the CPU 102, a work area, and the like. The CPU 102 controls each unit by a unit control circuit 104 (UCTRL). Note that the detector group 121 (DS) monitors the situation inside the inkjet recording apparatus 1, and the control unit CONT controls each unit based on the detection result.

The conveyance unit 111 (CONVU) controls sub-scanning (conveyance) of inkjet recording, and specifically controls the conveyance direction and conveyance speed of the recording medium M. Specifically, the conveyance direction and conveyance speed of the recording medium M are controlled by controlling the rotation direction and rotation speed of a conveyance roller driven by a motor.

The carriage unit 112 (CARU) controls the main scanning (pass) of inkjet recording, and specifically moves the inkjet head 2 back and forth in the main scanning direction. The carriage unit 112 includes a carriage 9 on which the inkjet head 2 is mounted, and a carriage movement mechanism 13 for reciprocating the carriage 9.

The head unit 113 (HU) controls the amount of water-based ink composition or water-based ink composition ejected from the nozzles of the inkjet head 2 . For example, if the nozzles of the inkjet head 2 are driven by piezoelectric elements, the operation of the piezoelectric elements in each nozzle is controlled. The head unit 113 controls the timing of adhesion of each ink, the dot size of the water-based ink composition, and the dot size of the water-based ink composition. Furthermore, the combination of controls of the carriage unit 112 and the head unit 113 controls the amount of water-based ink composition or water-based ink composition deposited per one scan.

The drying unit 114 (DU) controls the temperature of various heaters such as the heater 3, pre-heater 7, platen heater 4, and after-heater 5.

The inkjet recording apparatus 1 described above alternately repeats the operation of moving the carriage 9 on which the inkjet head 2 is mounted in the main scanning direction and the conveyance operation (sub-scanning). At this time, when performing each pass, the control unit CONT controls the carriage unit 112 to move the inkjet head 2 in the main scanning direction, and controls the head unit 113 to move the inkjet head 2 to a predetermined nozzle. A water-based ink composition or droplets of the water-based ink composition are ejected from the holes, and the water-based ink composition or droplets of the water-based ink composition are attached to the recording medium M. Further, the control unit CONT controls the transport unit 111 to transport the recording medium M in the transport direction by a predetermined transport amount (feed amount) during the transport operation.

In the inkjet recording apparatus 1, a recording area to which a plurality of droplets are attached is gradually transported by repeating main scanning (pass) and sub-scanning (conveyance operation). Then, the after-heater 5 dries the droplets attached to the recording medium M, and an image is completed. Thereafter, the completed recorded matter may be wound up into a roll by a winding mechanism or transported by a flatbed mechanism.

In the above, a serial type printing apparatus that is equipped with a serial type inkjet head and performs a serial type printing method has been described. On the other hand, the inkjet head may be a line type head. The inkjet head of the line-type recording device is a head in which nozzles are arranged in a length equal to or longer than the recording width of the recording medium M, and the aqueous ink composition is deposited on the recording medium M in one pass.

FIG. 4 is a schematic cross-sectional view schematically showing a part of a line-type recording apparatus that is equipped with a line-type head (line-type inkjet head) and performs a line-type recording method. The recording device section 200 includes an aqueous ink composition adhesion means 220 including an inkjet head 221 for an aqueous ink composition, an ink composition adhesion means 230 including an inkjet head 231 for an ink composition, and a conveyance roller 211 for conveying the recording medium M. The apparatus includes a recording medium conveyance means 210 including a recording medium, and a post-heating means 240 that performs a heating process (secondary heating) on the recording medium. In this embodiment, the post-heating means 240 is configured with an after-heater and/or a carbon heater, so that the image can be irradiated with infrared rays. The inkjet heads 231 and 221 are line-type inkjet heads in which nozzle rows extend in the width direction of the recording medium M, which is the front-back direction in the figure.

The line-type recording device transports the recording medium M in the transport direction, which is the direction of the arrow in FIG. etc. are ejected from an inkjet head and adhered to the recording medium M. This is called scanning. Scanning is also called main scanning or pass. The line type recording method is a one-pass recording method in which a water-based ink composition or an ink composition is applied to the conveyed recording medium M in one pass using the inkjet heads 231 and 221 to perform recording.

The line-type recording apparatus can be the same as the serial-type inkjet recording apparatus 1 described above, except that it includes a line-type inkjet head and performs a line-type recording method. The line type recording apparatus may be equipped with a drying means for performing a drying process. For example, drying means such as the ventilation fan 8 and heater 3 located above the inkjet head 2 in FIG. 1 may be provided above the inkjet heads 231 and 221 in FIG. Drying means such as an under heater corresponding to No. 4 may be provided below the inkjet heads 231 and 221 in FIG.

2.2. Details of Recording Medium Support Section FIG. 5 is a perspective view schematically showing an example of a recording medium support section (platen) with a flat support surface, which is included in the inkjet recording apparatus of this embodiment. In the example of the inkjet recording apparatus 1 described above, the recording medium support section is heated by the heating mechanism from the opposite side to the support surface 11a of the platen 11, which is the recording medium support section.

The platen 11, which is a recording medium support section, has a flat support surface 11a that supports the recording medium M, as shown in FIG. As already mentioned, when the recording medium M is supported by the support surface 11a, the area of the portion of the support surface 11a that supports the recording medium M during recording and that faces the inkjet head during recording is It is preferable that the support surface 11a be in contact with the recording medium M over 90.0% or more of the area. Here, the inkjet head is defined as the portion of the inkjet head where the nozzles that eject ink are present, from the upstream end to the downstream end in the recording medium conveyance direction. The ratio of the above-mentioned areas in contact is called the contact area ratio, and the ratio of the areas not in contact is called the non-contact area ratio.

The contact area ratio is more preferably 95.0% or more, further preferably 98.0% or more, and even more preferably 99.0% or more. On the other hand, the upper limit is 100% or less, may be 99.5% or less, or may be 99.0% or less.

In the example of FIG. 5, a suction hole 11c is formed in the support surface 11a of the platen 11 to suck the recording medium M (not shown) toward the support surface 11a. A suction device (not shown) is provided below the suction hole 11c. The suction holes 11c may be provided as necessary, but the total area of the suction holes 11c in the support surface 11a is less than 10% of the area of the support surface 11a. It is preferably 7% or less, more preferably 5% or less. In this way, it is possible to contact the recording medium M supported on the support surface 11a of the platen 11 over a wide area, and it is possible to conduct heat to the recording medium M with good uniformity. Further, it is possible to suppress the recording medium from floating off the support surface.

For example, the flat support surface does not have irregularities for intermittently supporting the recording medium on the support surface as described above, but it does not make contact with the recording medium within a range that does not cause excessive temperature unevenness of the recording medium. It may have some parts that do not. For example, in addition to suction holes, there may be joints, gaps, etc. that occur when manufacturing the support surface. Said non-contact area percentage of the support surface is less than 10%, preferably less than 7%, more preferably less than 5%, even more preferably less than 3%, even less than 2%, and even less than 1%. less than %. When the non-contact area ratio is below the above range, color difference reduction is more excellent and preferred. The lower limit of the non-contact area ratio is 0% or more, and may be 0.5% or more, although it is not limited thereto.

Further, it is preferable that the portions of the support surface of the support section that do not contact the recording medium M are distributed on the support surface, and preferably have a length of 3 cm or less in the main scanning direction as one continuous region. , 2 cm or less is more preferable, 1 cm or less is even more preferable, and 0.5 cm or less is particularly preferable. In this case, the non-contacting portions are subdivided, temperature unevenness can be reduced, and color difference can be further reduced, which is preferable. On the other hand, the lower limit is not limited, but is preferably 0.1 cm or more, more preferably 0.2 mm or more.

As a result, even if the ratio (A/B) in the water-based ink composition is 0.5 or more and 0.95 or less, and the reactivity when it comes into contact with the processing liquid is slow, it is possible to process the water-based ink composition on the recording medium. When the liquid and the aqueous ink composition are mixed and passed over the platen 11, the drying rate of the image is suppressed from varying depending on the portion of the recording medium, and unevenness in the aggregation rate is less likely to occur. Therefore, the degree of aggregation is unlikely to vary between locations where images of the same color are formed, and differences in color development are unlikely to occur. That is, an image with small in-plane color difference can be formed.

From this point of view, it is preferable that the width of the platen 11 in the direction perpendicular to the transport direction of the recording medium M is larger than the width in the direction perpendicular to the transport direction of the recording medium M. The thickness of the member forming the support surface 11a of the platen 11 is preferably 2.0 mm or more and 10.0 mm or less, more preferably 3.0 mm or more and 10.0 mm or less, and further preferably 5.0 mm or more and 10.0 mm or less. preferable. The member that constitutes the support surface 11a of the platen 11 is the outermost member on the recording medium side of the platen among the members that constitute the platen 11, and is a member that has a support surface. It is a plate-shaped member. The member may be made of metal, resin, etc., and metal is preferable because it has excellent heat conductivity. In the example of FIG. 5, the platen 11 is also the member. Examples of metals that can be used include, but are not limited to, iron, aluminum, stainless steel, copper, alloys containing these, and the like.

When the thickness of the member is greater than or equal to the above range, the heat capacity of the member increases, so that it is easier to suppress variations in the temperature reached due to the presence or absence of an image on the recording medium M, for example. This is preferable since the reduction in in-plane color difference is better. Moreover, when the thickness is below the above range, it is preferable that the platen can be easily heated by the heating mechanism.

3. EXAMPLES AND COMPARATIVE EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples and Comparative Examples. However, the present invention can be modified in various ways without departing from the spirit thereof, and is not limited in any way by the Examples below. It is not something that will be done. Regarding component amounts, % and parts are based on mass unless otherwise specified.

3.1. Preparation of Water-Based Ink Compositions and Treatment Liquids With the material compositions shown in Tables 1 and 2, C1 to C3 (water-based ink compositions) and OP1 to OP4 (treatment liquids) having different material compositions were prepared. For each ink and treatment liquid, the materials shown in Tables 1 and 2 are placed in a container, stirred and mixed using a magnetic stirrer for 2 hours, and then filtered through a membrane filter with a pore size of 5 μm to remove impurities such as dust and coarse particles. It was prepared by removing . Note that all values in Tables 1 and 2 indicate mass %, and pure water was added so that the total mass of the composition was 100 mass %.

Note that the coloring material (cyan pigment dispersion) used for preparing the water-based ink composition was manufactured in advance as follows.

<Dispersion liquid A>
Put 3 g of potassium persulfate and 30 g of water into a reaction vessel equipped with a stirrer, a reflux condenser, a dropping device, and a thermometer, and while stirring at 80°C under a nitrogen atmosphere, methacrylic acid/butyl acrylate/styrene/hydroxy. 40 g of a mixture of ethyl acrylate in a mass ratio of 25/50/15/10 was gradually added dropwise over 4 hours to polymerize. After polymerization, it was cooled to room temperature. Next, 7 parts by mass of potassium hydroxide, 23 parts by mass of water, and 30 parts by mass of triethylene glycol-mono-n-butyl ether were added to the liquid, and heated at 80°C with stirring to obtain an aqueous resin solution A. . The resin had a weight average molecular weight of 7000 and an acid value of 150 mgKOH/g).

Next, 20 parts by mass of pigment (C.I. Pigment Blue 15:3), 10 parts by mass of resin aqueous solution A, 10 parts by mass of diethylene glycol, and 60 parts by mass of ion-exchanged water were mixed and dispersed using a zirconia bead mill. Pigment dispersion A was obtained.

<Dispersion B>
A resin was prepared in the same manner. However, the monomer used was 40 parts by mass of St-Ac acid copolymer (methacrylic acid/butyl acrylate/styrene/hydroxyethyl acrylate = 20/45/20/15 mass ratio. After polymerization , 5.5 parts by mass of potassium hydroxide, 24.5 parts by mass of water, and 30 parts by mass of triethylene glycol-mono-n-butyl ether were added to the solution, and heated at 80° C. with stirring to prepare aqueous resin solution B. Prepared.
The resin had a weight average molecular weight of 7000 and an acid value of 120 mgKOH/g.
Next, 20 parts by mass of pigment (C.I. Pigment Blue 15:3), 10 parts by mass of resin aqueous solution B, 10 parts by mass of diethylene glycol, and 60 parts by mass of ion-exchanged water were mixed and dispersed using a zirconia bead mill. Pigment dispersion B was obtained.

Furthermore, in Table 1, the columns for pigment dispersion, resin, and wax indicate the mass % of the solid content calculated from the respective solid content concentrations. Table 1 also lists the average zeta potential of each of the inks C1 to C3 diluted 1000 times with water and measured with Zetasizer Nano ZS (manufactured by Malvern).

The substances in Tables 1 and 2 are as follows.
・Jonkryl 62J: Product name, manufactured by BASF, styrene acrylic resin. resin particles.
・AQUACER539: Product name, manufactured by Big Chemie Japan Co., Ltd., polyethylene wax ・Surfynol DF110D: Product name, manufactured by Air Products Co., Ltd., acetylene diol-based surfactant (antifoaming agent)
・BYK-348: Product name, BYK Chemie Japan Co., Ltd., silicone surfactant ・Cationmaster PD-7: Product name, Yokkaichi Gosei Co., Ltd., polyamine resin (epichlorohydrin-amine derivative resin)

3.2. Evaluation method 3.2.1. Measurement of ratio (A/B) The ratio (A/B) in each example was measured as follows. The absorbance (B) at the maximum peak wavelength in the range of 380.0 nm or more and 680 nm or less of the liquid obtained by dropping and stirring 0.04 g of the water-based ink composition against 40 g of pure water was measured. The absorbance (A) at the same wavelength as above of the liquid in which the water-based ink composition was dropped and stirred at the same ratio was measured, and the ratio (A/B) was determined. The average value was taken with the number of measurements taken as 3. The absorbance was measured using an ultraviolet-visible-near-infrared spectrophotometer V-700 manufactured by JASCO Corporation. The measurement was performed after stirring and standing still for 5 minutes. The measurement sample was taken from above the liquid level after it had come to rest.

3.2.2. Recording Test For the Examples and Comparative Examples listed in Tables 3 and 4, recorded matter was created under the following conditions using the treatment liquid, aqueous ink composition, and recording medium type listed in the Tables. As a printing machine, a modified machine (hereinafter also referred to as "SC-S40650 modified machine") was used, in which "SC-S40650" (model, manufactured by Seiko Epson Corporation) was equipped with a platen heater and a fan, which will be described later. The platen was made of aluminum and had a width of 1.6 m in the direction perpendicular to the conveying direction of the recording medium. Further, the width in the direction perpendicular to the conveying direction of the recording medium was 1.5 m. The resolution/number of scans was 720 x 1440 dpi/8 pass printing. The nozzle row of the inkjet head had a nozzle density of 360 dpi and a number of nozzles of 360 (nozzle row). The maximum temperature of the recording medium on the platen during printing is listed in Tables 3 and 4. The adhesion amounts of the aqueous ink composition and treatment liquid were 12 mg/inch ² for ink and 1.2 mg/inch ² for treatment liquid. The recording medium after the step of adhering ink, etc. was heated at 90° C. with an after-heater.

The types of recording media used are listed in Tables 3 and 4. The recording medium is as follows.
・M1: Orajet 3169G-010 (product name, manufactured by Orafol Japan Co., Ltd., polyvinyl chloride, base material thickness 100 μm)
・M2: Orajet 3651G-010 (product name, manufactured by Orafol Japan Co., Ltd., polyvinyl chloride, base material thickness 70 μm)

In addition, under the recording conditions, temperatures were measured at 20 locations at both ends and at predetermined intervals in the width direction on the recording surface side of the portion of the recording medium facing the inkjet head, and the difference between the maximum temperature and the minimum temperature was obtained. The maximum temperature and temperature difference (variation) are listed in Tables 3 and 4. Continuous recording was performed for 10 minutes or more, and the temperature was measured 10 minutes after the start of recording.

Furthermore, Tables 3 and 4 list the thickness and shape of the platen used in the recording test. In the example described as "flat" in the platen shape column, the platen had a support surface without ribs and had a flat support surface as shown in FIG. The shape was such that 99% or more of the area of the support surface was in contact with the recording medium. A suction hole was provided on the support surface, and the suction hole had a diameter of 4 mm. On the other hand, in the example described as "with ribs", a platen was used that was provided with ribs and had a shape in which less than 50% of the area of the support surface was in contact with the recording medium. The plate-like member constituting the support surface of the platen was made of aluminum, and its thickness was taken as the value in the table.

Furthermore, Tables 3 and 4 list the air temperature and air speed at the position of the inkjet head above the platen when air is blown by the fan.

3.2.3. Evaluation of in-plane color difference A "SC-S40650 modified machine" was filled with ink, and a solid pattern was recorded in the entire recordable range in the width direction. Color measurement was performed at 20 points at equal intervals near both ends in the width direction, and L*a*b* color difference (ΔE*ab) was measured using a spectrophotometer (manufactured by Gretag Macbeth, model: Spectrolino) as a D65 light source. (CIE1976/Hereinafter, L*a*b* color difference (ΔE*ab) is referred to as "color difference (ΔE)"). This is the color difference between colorimetric points. The evaluation was based on the following criteria, and the results are shown in Tables 3 and 4.
AA: ΔE is 1.5 or less A: ΔE is greater than 1.5 and 2.0 or less B: ΔE is greater than 2.0 and 2.5 or less C: ΔE is greater than 2.5

3.2.4. Evaluation of recovery from clogging after being left unused A simulated recording was performed with ink filled into the "SC-S40650 modified machine" and without capping. Specifically, the same operation as in printing under each printing condition was performed without ejecting ink from the head. The environment in which the printer was installed was an environment with a humidity of 20%. A simulated recording was conducted for one day. After that, cleaning was performed and the number of nozzles recovered was confirmed. In addition, in one cleaning, 1 g of ink was discharged from the nozzle row. The evaluation was based on the following criteria, and the results are shown in Tables 3 and 4.
AA: Recovery occurs within 2 cleanings A: Recovery occurs within 3 cleanings B: Recovery occurs within 6 cleanings C: Some nozzles do not recover even after 6 cleanings

3.2.5. Evaluation of clogging recovery performance of mixed liquid The "SC-S40650 modified machine" was filled with ink and the nozzle surface was lightly tapped with a bemcot soaked with the processing liquid to completely cause nozzle omission. After that, cleaning was performed and it was confirmed whether the nozzle omission was resolved. In addition, in one cleaning, 1 g of ink was discharged from the nozzle row. The evaluation was based on the following criteria, and the results are shown in Tables 3 and 4.
AA: Recovery occurs within 2 cleanings A: Recovery occurs within 3 cleanings B: Recovery occurs within 6 cleanings C: Some nozzles do not recover even after 6 cleanings

3.2.6. Evaluation of solid image quality A "SC-S40650 modified machine" was filled with ink, a recording medium (M1 or M2) with a width of 1.5 m was set, a cyan solid pattern was printed, and the printed matter was visually observed. The evaluation was based on the following criteria, and the results are shown in Tables 3 and 4.
AA: The ink is uniform and there are no areas where the ink appears to be unevenly shaded.A: There are some areas where the ink is unevenly shaded, but it is not noticeable.B: There are areas where the ink is unevenly shaded. Somewhat worrisome C: There are quite a few places where the ink is unevenly shaded, which is quite worrisome.

3.3. Evaluation Results An inkjet recording device includes a recording medium support portion having a flat support surface and a heating mechanism that heats the recording medium support portion, and a water-based ink composition is applied to the recording medium heated and supported by the recording medium support portion. The ratio (A/B) of the aqueous ink composition is 0.5 or more and 0.95 or less, and the maximum temperature of the surface of the recording medium is 28.0°C or more and 45.0°C or more in the ink adhesion step. In each of the examples heated to temperatures below .degree. C., both the in-plane color difference and clogging recovery properties were good.

On the other hand, all of the other comparative examples were inferior in either in-plane color difference or clogging recovery performance. Details are given below.
From Examples 1 to 5, the higher the ratio (A/B), the better the clogging recovery performance, and the lower the ratio, the better the in-plane color difference reduction and image quality.
From Examples 1 and 6, the thicker the platen, the better the in-plane color difference reduction.
From Examples 1 and 11, the thicker the recording medium was, the better the in-plane color difference reduction and image quality were.
From Examples 1, 7 to 9, and 14, the in-plane color difference reduction and image quality were better when air was used. Furthermore, the higher the wind temperature and wind speed, the better the in-plane color difference reduction and image quality were, and the lower the wind temperature and wind speed, the better the recovery from clogging.
From Comparative Example 1, when no processing liquid was used, the in-plane color difference reduction and image quality were poor.
From Comparative Example 2, when the ratio (A/B) was less than 0.5, clogging recovery was poor.
From Comparative Example 3, when the support surface was not flat, the in-plane color difference was poor. In Comparative Example 4, the ratio (A/B) was less than 0.5, and although the supporting surface was not flat, the in-plane color difference was not inferior. From this, it is estimated that in-plane color difference reduction can occur when the ratio (A/B) is 0.5 or more.
Comparative Examples 5 and 6 show that when the temperature of the recording medium on the platen was too high, clogging recovery was poor, and when it was too low, in-plane color difference reduction and image quality were poor.

The present invention is not limited to the embodiments described above, and various modifications are possible. For example, the present invention includes configurations that are substantially the same as those described in the embodiments (for example, configurations that have the same functions, methods, and results, or configurations that have the same objectives and effects). Further, the present invention includes a configuration in which non-essential parts of the configuration described in the embodiments are replaced. Further, the present invention includes a configuration that has the same effects or a configuration that can achieve the same purpose as the configuration described in the embodiment. Further, the present invention includes a configuration in which a known technique is added to the configuration described in the embodiment.

DESCRIPTION OF SYMBOLS 1... Inkjet recording device, 2... Inkjet head, 2a... Nozzle surface, 3... Heater, 4... Platen heater, 5... After heater, 6... Fan, 7... Preheater, 8... Ventilation fan, 9... Carriage, 11... Platen, 11a... Support surface, 11c... Suction hole, 12... Cartridge, 13... Carriage moving mechanism, 14... Conveyance means, 71... Housing, 72... Guide, 101... Interface unit, 102... CPU, 103... Memory, 104 ... Unit control circuit, 111 ... Transport unit, 112 ... Carriage unit, 113 ... Head unit, 114 ... Drying unit, 121 ... Detector group, 130 ... Computer, 200 ... Portion of line type recording device, 210 ... Recording medium transport means , 211... Conveyance roller, 220... Treatment liquid adhesion means, 221... Inkjet head, 230... Composition adhesion means, 231... Inkjet head, 240... Post-heating means, CONT... Control unit, MS... Main scanning direction, SS... Sub- Scanning direction, M...Recording medium

Claims (16)

An inkjet recording method using an inkjet recording device, the method comprising:
a processing liquid adhesion step of adhering a processing liquid containing a flocculant to a recording medium;
an ink adhesion step of ejecting an aqueous ink composition containing a coloring material from an inkjet head and adhering it to the recording medium;
Equipped with
The inkjet recording device includes:
a recording medium support section that supports the recording medium;
a heating mechanism that heats the recording medium support section;
Equipped with
The ink adhering step is performed on the recording medium supported and heated by the recording medium supporter,
In the ink adhering step, the recording medium is heated to a maximum temperature of 28.0° C. or more and 45.0° C. or less on the surface of the recording medium supported by the recording medium supporting portion and facing the inkjet head. ,
The water-based ink composition has a ratio of 0.1% by mass of the water-based ink composition to the treatment liquid relative to the absorbance B at the maximum peak wavelength of a mixed liquid in which 0.1% by mass of the water-based ink composition is mixed with pure water. The ratio (A/B) of absorbance A at the wavelength of the 1% by mass mixed liquid is 0.5 or more and 0.95 or less,
The recording medium support section has a flat support surface that supports the recording medium, a suction hole is formed in the support surface, and a portion of the support surface that supports the recording medium and faces the inkjet head. The support surface is in contact with the recording medium in an area of 90.0% or more of the area of
The inkjet recording method , wherein the aggregating agent contains a polyvalent metal salt that is a magnesium salt . In claim 1,
An inkjet recording method, wherein the ink adhesion step is performed by performing main scanning and sub-scanning on the recording medium a plurality of times. In claim 1 or claim 2,
In the ink adhering step, a temperature difference in the in-plane distribution of the surface temperature of the recording medium at a portion supported by the recording medium support portion and facing the inkjet head is 8.0° C. or less. Method. In any one of claims 1 to 3,
In the inkjet recording method, the heating mechanism heats the recording medium support section from a side opposite to the support surface. In any one of claims 1 to 4,
An inkjet recording method, wherein the aqueous ink composition has an average zeta potential of -65.0 mV or more and -50.0 mV or less. In any one of claims 1 to 5,
An inkjet recording method, wherein the width of the recording medium in the direction perpendicular to the conveyance direction is 0.5 m or more. In any one of claims 1 to 6,
An inkjet recording method, wherein the width of the recording medium support portion in the direction perpendicular to the conveyance direction of the recording medium is larger than the width in the direction perpendicular to the conveyance direction of the recording medium. In any one of claims 1 to 7,
An inkjet recording method, wherein the thickness of the member constituting the support surface of the recording medium support part is 2.0 mm or more and 10.0 mm or less. In any one of claims 1 to 8,
An inkjet recording method, wherein the ink adhesion step includes a blowing step of blowing air onto the recording medium to which the water-based ink composition has been adhered by a blowing mechanism. In claim 9,
An inkjet recording method, wherein the speed of air blown onto the recording medium is 1.0 m/sec or more. In claim 9 or claim 10,
An inkjet recording method, wherein the temperature of the air blown onto the recording medium is 45.0°C or less. In any one of claims 1 to 11,
An inkjet recording method, wherein the ratio (A/B) is 0.7 or more and 0.9 or less. In any one of claims 1 to 12,
An inkjet recording method, wherein the thickness of the recording medium is 40.0 μm or more. In any one of claims 1 to 13,
An inkjet recording method, wherein the aqueous ink composition does not contain more than 1.0% by mass of an organic solvent having a normal boiling point of more than 280.0°C. In any one of claims 1 to 14,
An inkjet recording method, wherein the support surface is in contact with the recording medium over an area of 95.0 % or more of the area of the portion of the support surface that supports the recording medium and faces the inkjet head. A recording apparatus that performs the inkjet recording method according to any one of claims 1 to 15.

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