JP2008068462A - Inkjet recording method provided with drying process for paper, recording apparatus and ink for it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for obtaining an image with rapid dryableness, less fluctuation of image density and a high image quality when a general-purpose and commercially available printing paper which has a lower water absorbing capability than those of an ordinary paper of fine quality and a paper for inkjet exclusive use is printed, its apparatus and an ink for it. <P>SOLUTION: The inkjet recording method is characterized in that a recording medium undergoes inkjet printing under a condition that the water content of the recording medium being a paper medium is made to an equilibrium water content or less at a temperature/a humidity at the time of printing in advance. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an ink jet recording method and a recording apparatus, and ink for the same.

The inkjet recording method is a printing method in which printing is performed by causing small droplets of ink to fly and adhere to a recording medium (media) such as paper. As ink-jet ink compositions, generally used are colorants of various dyes and pigments dissolved in water or water and an organic solvent, and further containing a large amount of a wetting agent composed of a high-boiling organic solvent. The wetting agent composed of this high-boiling organic solvent contributes to prevention of drying of the nozzle due to its water retention ability.
On the other hand, general-purpose and commercially available printing paper that is not dedicated to inkjet paper, such as offset coated paper for printing, calendar paper, catalog paper, packaging material, label printing paper, etc. Is difficult to penetrate, so it takes a long time to dry and is not practical.
Therefore, there has been a demand for a method that can be dried quickly even on such printing paper, has high image density, has high image quality on plain paper, and does not cause nozzle clogging when stopped for a long time.

On the other hand, when printing is performed on such offset-coated paper, Patent Document 1 discloses a method of performing high-frequency heating after printing. As described above, heating after printing cannot prevent unevenness in image density due to unevenness of ink liquid on paper before drying due to slow drying. The same applies to Patent Document 2.
Patent Document 3 discloses a method in which the heating step is applied in the printing process or applied after the printing step. Heating during the printing process inevitably affects the head and thus the jetting stability.
Patent Document 4 is also a method of drying ink during or after the ink jet printing process.
The same applies to Patent Document 5. The same applies to Patent Document 6.

JP 2002-69346 A JP 2006-22328 A JP 2004-114691 A Special Table 2003-534164 JP 2001-301131 A Japanese Patent No. 3472470

  Accordingly, the object of the present invention is to reduce the water absorption capacity compared to ordinary high-quality paper and ink-jet dedicated paper in view of the above-mentioned prior art, and when printing on general-purpose commercial printing paper, the drying property is fast and the image density is high. To provide a method and apparatus for obtaining a high-quality image with little unevenness, and an ink therefor.

The paper medium used in the present invention is not capable of absorbing water like ordinary plain paper (quality paper), and the surface is coated with a large amount of a porous substrate so as to have high-speed water absorption ability. It is not so-called inkjet paper. It is a smooth paper with a small water absorption capacity as described above.
That is, the recording medium has a support and a coating layer on at least one surface of the support, and pure water is applied to the recording medium at a contact time of 100 ms measured with a dynamic scanning absorptiometer. The transfer amount is ² to 35 ml / m ² , and the transfer amount of pure water to the recording medium at a contact time of 400 ms is 3 to 40 ml / m ² . When printing directly on such paper, when the ink adhesion amount is large, the liquid drying property is slow, and therefore, density unevenness due to liquid deviation tends to occur.
In order to suppress this, it is still unclear whether it is effective to dry the paper after printing to reduce the moisture content. It was thought that when the water content was reduced, the effect of priming water was lost and the drying was rather delayed.

As a result of intensive studies, if the moisture content is 75% by mass or less, preferably 50% by mass or less of the equilibrium moisture content of the temperature and humidity of the printing environment, the dryness of the printed image after printing is improved and density unevenness is suppressed. It was found that the transfer to the member was difficult to occur.
However, the moisture absorption rate of the paper after drying was surprisingly fast, and it was found that the drying rate of the image could not be brought to a practical level unless it was printed within 1 minute after heating.
Furthermore, when the paper transport method is a method in which the paper is electrostatically attracted to a charged belt, if the paper is dried in this way, mist is likely to be generated during printing. To prevent this mist, at least ink It has been found that an inkjet ink having an electric conductivity of 2000 μS / cm or less is preferable.
In addition, it was found that ink having a low surface tension with a silicon-based or fluorine-based surfactant is suitable for high-speed high-quality printing in combination with heat drying.
Further, when the recording medium after printing is also dried, double-sided printing is performed promptly. The drying space can be the same as before printing or a different space.

That is, the above-described problem is (1) “Inkjet printing on a recording medium in which the moisture content of the recording medium, which is a paper medium, is previously set to be equal to or less than the equilibrium moisture content at the temperature and humidity during printing. Inkjet recording method characterized by "
(2) “Including the operation of forcing the recording paper medium to be equal to or less than the equilibrium water content at the temperature and humidity at the time of printing in advance and the operation of performing inkjet printing on the recording medium after the operation. The inkjet recording method according to item (1),
(3) “Ink jet recording method according to item (2), further including a drying operation for drying the recording medium after printing”;
(4) “The recording medium comprises a support and a coating layer on at least one surface of the support, and the recording of pure water at a contact time of 100 ms measured by a dynamic scanning absorptiometer” a transfer amount is 2~35ml / ^{m 2} to use the media, and the transfer amount of to the recording medium of pure water at the contacting time 400ms is 3~40ml / ^{m 2} paragraph (1), second ( 3) Inkjet recording method according to any one of items ”
(5) Characteristically, printing is performed with the moisture content in the paper being 75% by mass or less, preferably 50% by mass or less of the equilibrium moisture content of the temperature and humidity during printing (usually normal temperature and normal humidity-23 ° C, 50RH%). The inkjet recording method according to any one of (1) to (4) above,
(6) According to any one of (1) to (5), wherein the forced drying operation of the recording medium is a heating operation, and printing is performed within 1 minute after the heating. This is achieved by the “inkjet recording method”.
In addition, the above-mentioned problem is (7) “a recording paper medium in which the recording paper medium is preliminarily equal to or less than the equilibrium moisture content at the temperature and humidity at the time of printing, and the recording medium after passing through the moisture reduction means. Inkjet recording apparatus having printing means for inkjet printing ",
(8) This is achieved by “an ink jet recording apparatus according to item (7), further including a drying means for drying the recording medium after printing”.
In addition, the above-mentioned problem is (9) “ink-jet recording ink for ink-jet printing, wherein the paper is electrostatically attracted to a belt charged by a recording-paper medium transport system for ink-jet printing. The recording paper medium is inkjet-printed in a state where the moisture content is equal to or less than the equilibrium moisture content at the temperature and humidity during recording, and the inkjet ink has an electrical conductivity of 2000 μS / cm or less. Ink for ink jet recording characterized by ",
(10) “(9) characterized in that it contains at least a colorant, a water-dispersible resin, a wetting agent, a surfactant, and water, and the surfactant is a silicon-based or fluorine-based surfactant. This is achieved by the ink-jet recording ink described in the item).

As is clear from the detailed and specific description below,
According to (1), (2) and (7), the drying property after printing is improved by heating the paper below the equilibrium moisture content. Reduces image density unevenness;
Also, according to (3) and (8), when the recording medium after printing is further dried, double-sided printing is performed promptly. The drying space can be the same as before printing or a different space.
According to (4), the recording medium has a support and a coating layer on at least one surface of the support, and the recording of pure water at a contact time of 100 ms measured with a dynamic scanning absorptiometer. a transfer amount is 2~35ml / ^{m 2} to use the media, and although the amount of transferred to the recording medium of pure water at a contact time of 400ms paper has poor drying properties is 3~40ml / ^{m 2,} the The invention improves drying properties;
According to (5), if it is 75% or less, preferably 50% by mass or less of the equilibrium moisture content of the temperature and humidity of the printing environment, the dryness of the printed image after printing is improved, density unevenness is suppressed, and Transcription is less likely to occur;
According to (6), it was found that the moisture absorption rate of the paper after drying was surprisingly fast, and the image drying rate could not be brought to a practical level unless printed within 1 minute after heating;
According to (9), when the paper transport method is a method in which the paper is electrostatically attracted to the charged belt, if the paper is dried in this way, mist is likely to be generated during printing, and this mist is prevented. It has been found that at least an ink-jet ink having an ink electrical conductivity of 2000 μS / cm or less is preferred;
In addition, (10) indicates that ink having a low surface tension with a silicon-based or fluorine-based surfactant is suitable for high-speed high-quality printing in combination with heat drying;
This is an extremely excellent effect.

Hereinafter, the present invention will be described in more detail.
[media]
The ink medium of the present invention is as follows. However, it can be applied to any ordinary inkjet paper or plain paper that has a slow drying speed. Furthermore, it can be developed in the case of a non-water-absorbing medium such as a plastic film or metal.

[Recording media]
The recording medium includes a support and a coating layer on at least one surface of the support, and further includes other layers as necessary.

In the recording medium, the transfer amount of pure water to the recording medium at a contact time of 100 ms measured with a dynamic scanning absorption meter is ² to 35 ml / m ² , and preferably ² to 10 ml / m ^2. .
The transfer amount of the pure water to the recording medium at a contact time of 400 ms measured with a dynamic scanning absorption meter is 3 to 40 ml / m ² , and preferably 3 to 10 ml / m ² .
The present invention is effective when high-speed printing is performed on such paper with a large amount of ink attached.

  Here, the dynamic scanning absorptiometer (DSA, Papa-Pagi Technical Journal, Vol. 48, May 1994, pp. 88-92, Kuju Shigenori) absorbs liquid in a very short time. It is a device that can measure accurately. The dynamic scanning absorption meter reads the liquid absorption speed directly from the movement of the meniscus in the capillary, makes the sample a disk, and then scans the liquid absorption head in a spiral shape, and the scanning speed according to a preset pattern. Is automatically changed by a method in which the number of necessary points is measured with one sample. A liquid supply head for a paper sample is connected to a capillary via a Teflon (registered trademark) tube, and the position of the meniscus in the capillary is automatically read by an optical sensor. Specifically, the transfer amount of pure water or ink was measured using a dynamic scanning absorption meter (K350 series D type, manufactured by Kyowa Seiko Co., Ltd.). The transfer amount at the contact time of 100 ms and the contact time of 400 ms can be obtained by interpolation from the measured value of the transfer amount at the contact time adjacent to each contact time.

-Support-
The support is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include paper based on wood fibers, and sheet-like materials such as non-woven fabrics mainly composed of wood fibers and synthetic fibers. .
As the internal filler used for the support, for example, a conventionally known pigment is used as a white pigment. Examples of the white pigment include light calcium carbonate, heavy calcium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zinc carbonate, satin white, aluminum silicate, diatomaceous earth, White inorganic pigments such as calcium silicate, magnesium silicate, synthetic silica, aluminum hydroxide, alumina, lithopone, zeolite, magnesium carbonate, magnesium hydroxide; styrene plastic pigment, acrylic plastic pigment, polyethylene, microcapsule, urea resin And organic pigments such as melamine resin. These may be used individually by 1 type and may use 2 or more types together.

-Coating layer-
The coating layer contains a pigment and a binder (binder), and further contains a surfactant and other components as necessary.
As the pigment, an inorganic pigment or a combination of an inorganic pigment and an organic pigment can be used.
Examples of the inorganic pigment include kaolin, talc, heavy calcium carbonate, light calcium carbonate, calcium sulfite, amorphous silica, titanium white, magnesium carbonate, titanium dioxide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, Examples thereof include zinc hydroxide and chlorite.
The amount of kaolin added is preferably 50 parts by mass or more with respect to 100 parts by mass of the binder. When the addition amount is less than 50 parts by mass, a sufficient effect on glossiness may not be obtained. The upper limit of the addition amount is not particularly limited, but is preferably 90 parts by mass or less from the viewpoint of coating suitability in consideration of the fluidity of kaolin, particularly the thickening under high shear force.

Examples of the organic pigment include water-soluble dispersions such as styrene-acrylic copolymer particles, styrene-butadiene copolymer particles, polystyrene particles, and polyethylene particles. Two or more of these organic pigments may be mixed.
The addition amount of the organic pigment is preferably 2 to 20 parts by mass with respect to 100 parts by mass of the total pigment in the coating layer. Since the organic pigment is excellent in gloss expression and its specific gravity is smaller than that of an inorganic pigment, it is possible to obtain a coating layer that is bulky, high gloss, and has good surface coverage. It is preferable to use an aqueous resin. As the aqueous resin, at least one of a water-soluble resin and a water-dispersible resin is preferably used.
2-100 mass parts is preferable with respect to 100 mass parts of said pigments, and, as for the addition amount of the said aqueous resin, 3-50 mass parts is more preferable. The amount of the aqueous resin added is determined so that the liquid absorption characteristics of the recording medium fall within a desired range.
There is no restriction | limiting in particular as a formation method of the said coating layer, According to the objective, it can select suitably, It can carry out by the method of impregnating or apply | coating a coating layer liquid on the said support body. The impregnation or coating method of the coating layer liquid is not particularly limited and may be appropriately selected depending on the intended purpose. For example, conventional size press, gate roll size press, film transfer size press, blade coater, rod coater It is possible to coat with various coating machines such as air knife coater and curtain coater, but from the viewpoint of cost, conventional size press, gate roll size press, film transfer size press etc. installed in paper machine It may be impregnated or deposited and finished on-machine.
There is no restriction | limiting in particular in the adhesion amount of the said coating layer liquid, According to the objective, it can select suitably, 0.5-20 g / m < ² > is preferable at solid content, and 1-15 g / m < ² > is more preferable. .
After the impregnation or application, drying may be performed as necessary. In this case, the drying temperature is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably about 100 to 250 ° C. .

The recording medium may further include a back layer on the back surface of the support, another layer between the support and the coating layer, or another layer between the support and the back layer, and a protective layer on the coating layer. Can also be provided. Each of these layers may be a single layer or a plurality of layers.
The recording medium may be commercially available coated paper for offset printing, coated paper for gravure printing, etc., as long as the liquid absorption property is within the range of the present invention.

[ink]
-Colorant-
When a pigment is used as the colorant, an ink having excellent light resistance can be obtained. There is no restriction | limiting in particular as said pigment, Although the pigment for normal inkjets is used, the following are preferable.
(1) Pigment having a hydrophilic group on the pigment surface (2) Polymer emulsion type pigment comprising polymer fine particles containing a water-insoluble or poorly water-soluble colorant (3) Micro-coated with a resin having a hydrophilic group Capsule type pigments In addition, pigment inks in which pigments are dispersed and stabilized with a surfactant or a water-soluble resin dispersant may also be used.

  The pigment (1) is surface-modified so that at least one hydrophilic group is bonded to the surface of the pigment directly or via another atomic group. In the surface modification, a specific functional group (a functional group such as a sulfone group or a carboxyl group) is chemically bonded to the surface of the pigment, or at least one of hypohalous acid and a salt thereof is used. A method such as wet oxidation is used. Among these, a form in which a carboxyl group is bonded to the surface of the pigment and dispersed in water is particularly preferable. Since the pigment is thus surface-modified and the carboxyl group is bonded, not only the dispersion stability is improved, but also high-quality printing quality is obtained and the water resistance of the recording medium after printing is further improved. To do.

In the pigment (2), the polymer emulsion containing a colorant means at least one of a polymer fine particle encapsulated with the pigment and a polymer fine particle surface adsorbed with the pigment. For example, what was described in Unexamined-Japanese-Patent No. 2001-139849 etc. are mentioned.
In this case, it is not necessary that all the pigments are encapsulated and / or adsorbed in the polymer fine particles, and the pigments may be dispersed in the emulsion as long as the effects of the present invention are not impaired.
The “water-insoluble or hardly water-soluble” means that the coloring material does not dissolve 10 parts by mass or more with respect to 100 parts by mass of water at 20 ° C. The term “dissolves” means that separation or sedimentation of the coloring material is not observed on the surface layer or lower layer of the aqueous solution.
The polymer that forms the polymer emulsion is not particularly limited and may be appropriately selected depending on the intended purpose. For example, vinyl polymers, polyester polymers, polyurethane polymers, JP 2000-53897 A, JP The polymer etc. which are indicated by 2001-139849 gazette are mentioned. Among these, vinyl polymers and polyester polymers are particularly preferable.
The volume average particle diameter of the polymer fine particles (colored fine particles) containing the coloring material is preferably 0.01 to 0.16 μm in the ink.
When the pigment (2) is used, an ink excellent in light resistance and fixability can be obtained.

The pigment (3) is obtained by coating the pigment with a hydrophilic water-insoluble resin and making it hydrophilic in the resin layer on the surface of the pigment so as to disperse the pigment in water. What was described in 2002-67473 gazette etc. are mentioned.
When the pigment (3) is used, an ink excellent in light resistance and fixability can be obtained.
The pigments (1), (2), and (3) exhibit particularly improved drying and high color tone when the composition ratio of the ink of the present invention is used.

Examples of organic pigments include azo, phthalocyanine, anthraquinone, quinacridone, dioxazine, indigo, thioindigo, perylene, isoindolenone, aniline black, azomethine, rhodamine B lake pigment, and carbon black. It is done.
Examples of inorganic pigments include iron oxide, titanium oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, bitumen, cadmium red, chrome yellow, and metal powder.
The particle diameter of these pigments is preferably 0.01 to 0.30 [mu] m. If the particle diameter is 0.01 [mu] m or less, the light resistance and feathering are deteriorated because the particle diameter approaches that of the dye. On the other hand, if it is 0.30 μm or more, clogging of the discharge port or clogging with a filter in the printer occurs, and the discharge stability cannot be obtained.

  The carbon black used in the black pigment ink is carbon black produced by the furnace method and the channel method, the primary particle size is 15 to 40 millimicrons, the specific surface area by the BET method is 50 to 300 square meters / g, The DBP oil absorption is preferably 40 to 150 ml / 100 g, the volatile content is 0.5 to 10%, and the pH value is 2 to 9. As such a thing, for example, no. 2300, no. 900, MCF-88, no. 33, no. 40, no. 45, no. 52, MA7, MA8, MA100, no. 2200B (Mitsubishi Chemical), Raven700, 5750, 5250, 5000, 3500, 1500 (Columbia), Regal 400R, 330R, 660R, MoguL, Monarch 700, 800, 880, 900, 1000, 1100, 1300, Monarch 1400 (above, manufactured by Cabot), Color Black FW1, FW2, FW2V, FW18, FW200, S150, S160, S170, Printex 35, U, the same V, the same 140U, the same 140V, the special black 6, the same 5, the same 4A, the same 4 (manufactured by Degussa) and the like can be used, but are not limited thereto.

Specific examples of color pigments are listed below.
Examples of organic pigments include azo, phthalocyanine, anthraquinone, quinacridone, dioxazine, indigo, thioindigo, perylene, isoindolenone, aniline black, azomethine, rhodamine B lake pigment, and carbon black. Examples of inorganic pigments include iron oxide, titanium oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, bitumen, cadmium red, chrome yellow, and metal powder.
Specific examples according to color are as follows.
Examples of pigments that can be used for yellow ink include C.I. I. Pigment Yellow 1, 2, 2, 3, 12, 14, 16, 17, 17, 73, 74, 75, 83, 93, 95, 97, 98, 114, 128, 129, 151, 154, etc., but are not limited thereto.
Examples of pigments that can be used in magenta ink include C.I. I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 112, 123, 168, 184, 202, etc. However, it is not limited to these.
Examples of pigments that can be used for cyan ink include C.I. I. Pigment blue 1, 2, 3, 15: 3, 15:34, 16, 22, 22, 60, C.I. I. Examples thereof include, but are not limited to, Bat Blue 4 and 60.
In addition, the pigment contained in each ink used in the present invention may be newly produced for the present invention.

-Water dispersible resin-
The resin can be appropriately selected according to the purpose, but resin fine particles are preferable from the viewpoint that the amount of resin added can be increased.
The resin fine particles present as a resin emulsion dispersed in water as a continuous phase are used at the time of ink production. The resin emulsion may contain a dispersant such as a surfactant as necessary.
The content of resin fine particles as the dispersed phase component (content of resin fine particles in resin emulsion solution: not content in recording ink after production) is generally preferably 10 to 70% by mass.
The particle diameter of the resin fine particles is preferably 10 to 1,000 nm, more preferably 100 to 300 nm, particularly considering use in an ink jet recording apparatus. This is the particle diameter in the resin emulsion, but in the case of a stable recording ink, there is no significant difference between the particle diameter in the resin emulsion and the resin fine particle diameter in the recording ink. The larger the volume average particle diameter is, the more emulsion can be added. If the volume average particle size is less than 100 nm, the amount of emulsion added may not be increased, and if it exceeds 300 nm, reliability may be reduced. However, it is not always possible to use an emulsion having a particle size outside this range. These are general trends regardless of the type of emulsion.
Here, the volume average particle diameter can be measured using, for example, a particle size analyzer (Microtrac Model UPA9340, manufactured by Nikkiso Co., Ltd.).
Specifically, the emulsion aqueous solution is diluted within the signal level optimum range and measured under the conditions of transparency-YES, provisional index 1.49, partial density 1.19, spherical particles-YES, medium-water. Here, the value of 50% was defined as the volume average particle size.
The resin particles in the dispersed phase are not particularly limited and can be appropriately selected according to the purpose. For example, urethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, butadiene resin, Examples include styrene-butadiene resins, vinyl chloride resins, acrylic styrene resins, acrylic silicone resins, and fluorine resins.

As said resin emulsion, what was synthesize | combined suitably may be used and a commercial item may be used.
Examples of the commercially available resin emulsion include Microgel E-1002, E-5002 (styrene-acrylic resin emulsion, manufactured by Nippon Paint Co., Ltd.), and Boncoat 4001 (acrylic resin emulsion, manufactured by Dainippon Ink & Chemicals, Inc.). ), Boncoat 5454 (styrene-acrylic resin emulsion, manufactured by Dainippon Ink & Chemicals, Inc.), SAE-1014 (styrene-acrylic resin emulsion, manufactured by Nippon Zeon Co., Ltd.), Cybinol SK-200 (acrylic resin emulsion, Seiden Chemical Co., Ltd.), Primal AC-22, AC-61 (acrylic resin emulsion, manufactured by Rohm and Haas), Nanoacryl SBCX-2821, 3689 (acrylic silicone resin emulsion, Toyo Ink Co., Ltd.) Company Ltd.), # 3070 (methyl methacrylate polymer resin emulsion, manufactured by Mikuni Color Ltd.).
Among these, an acrylic silicone emulsion is particularly preferable from the viewpoint of good fixability.
The glass transition temperature of the resin component in the acrylic silicone emulsion is preferably 25 ° C. or less, and more preferably 0 ° C. or less. When the glass transition temperature exceeds 25 ° C., the resin itself becomes brittle, which causes deterioration of fixability. In particular, in the case of a printing paper that is smooth and hardly absorbs water, a decrease in fixing property may appear. However, even if the glass transition temperature is 25 ° C. or higher, it cannot always be used.
The glass transition temperature can be measured using, for example, a differential scanning calorimeter (manufactured by Rigaku Corporation).
Specifically, the resin piece of the room temperature dry film of the resin emulsion aqueous solution was heated from around −50 ° C. with a Rigaku-electric differential scanning calorimeter, and the temperature was determined at a temperature at which a step was generated.

-Wetting agent (high boiling water-soluble organic solvent)-
The so-called wetting agent can be appropriately selected according to the purpose. For example, polyhydric alcohols, polyhydric alcohol alkyl ethers, polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines , Sulfur-containing compounds, propylene carbonate, ethylene carbonate and the like. These may be used alone or in combination of two or more.

Examples of the polyhydric alcohols include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polypropylene glycol, 1,3-propanediol, 1,3-butanediol, 2,3-butanediol, 1,4 butanediol, 3-methyl-1,3-butanediol, 1,5 pentanediol, 1,6 hexanediol, 2-methyl-2,4-pentanediol, tetraethylene glycol Polyethylene glycol, glycerin, 1,2,6-hexanetriol, 1,2,4-butanetriol, 1,2,3-butanetriol, and petriol.
Examples of the polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether. It is done.
Examples of the polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.
Examples of the nitrogen-containing heterocyclic compound include N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, and ε-caprolactam.
Examples of the amides include formamide, N-methylformamide, formamide, N, N-dimethylformamide and the like.
Examples of the amines include monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, and triethylamine.
Examples of the sulfur-containing compounds include dimethyl sulfoxide, sulfolane, thiodiethanol, thiodiglycol, and the like.
Among these, glycerin, 2-pyrrolidone, diethylene glycol, thiodiethanol, polyethylene glycol, triethylene glycol, 1,2,6-hexanetriol, 1,2,4-butanetriol, petri from the viewpoint of ink ejection stability. All, 1,5-pentanediol, N-methyl-2-pyrrolidone, 1,3-butanediol, and 3-methyl-1,3-butanediol are preferred. Among these, glycerin, 1,3-butanediol, 3-methyl-1,3-butanediol and 2-pyrrolidone are particularly preferred.

-Surfactant-
The surfactant is not particularly limited and can be appropriately selected from surfactants that do not impair dispersion stability depending on the purpose, depending on the type of coloring agent, a wetting agent, a penetrating agent, and the like. In particular, when printing on printing paper, those having low surface tension and high leveling properties are preferred, and at least one selected from silicone surfactants and fluorosurfactants is preferred. Among these, a fluorine-based surfactant is particularly preferable.

As said fluorosurfactant, what has a C2-C16 organic group which the fluorine substituted is preferable, and 4-16 are more preferable. When the fluorine-substituted carbon number is less than 2, the effect of fluorine may not be obtained, and when it exceeds 16, problems such as ink storage stability may occur.
Examples of the fluorosurfactant include perfluoroalkyl sulfonic acid compounds, perfluoroalkyl carboxylic acid compounds, perfluoroalkyl phosphate compounds, perfluoroalkyl ethylene oxide adducts, and perfluoroalkyl ether groups. And polyoxyalkylene ether polymer compounds having a chain. Among these, a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain is particularly preferable because of its low foaming property.

Examples of the perfluoroalkyl sulfonic acid compound include perfluoroalkyl sulfonic acid, perfluoroalkyl sulfonate, and the like.
Examples of the perfluoroalkyl carboxylic acid compounds include perfluoroalkyl carboxylic acids and perfluoroalkyl carboxylates.
Examples of the perfluoroalkyl phosphate compound include perfluoroalkyl phosphate esters, perfluoroalkyl phosphate salts, and the like.
The polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain includes a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain, and a polyoxyalkylene ether having a perfluoroalkyl ether group in the side chain. Examples thereof include a sulfate salt of a polymer and a salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain.
As counter ions of salts in these fluorosurfactants, Li, Na, K, NH ₄ , NH ₃ CH ₂ CH ₂ OH, NH ₂ (CH ₂ CH ₂ OH) ₂ , NH (CH ₂ CH ₂ OH) ₃ etc. are mentioned.

As said fluorosurfactant, what was synthesize | combined suitably may be used and a commercial item may be used.
Examples of the commercially available products include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, and S-145 (all manufactured by Asahi Glass Co., Ltd.), Fullrad FC. -93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (all manufactured by Sumitomo 3M), MegaFuck F-470, F1405, F-474 (All manufactured by Dainippon Ink & Chemicals, Inc.), Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR (all manufactured by DuPont), FT-110, FT- 250, FT-251, FT-400S, FT-150, FT-400SW (all manufactured by Neos Co., Ltd.), PF-151N (manufactured by Omninova) Among these, FT-110, FT-250, FT-251, FT-400S, manufactured by Neos Co., Ltd., from the point that the good print quality, particularly the color developability and the leveling property on paper are remarkably improved. FT-150, FT-400SW and OM-nova PF-151N are particularly preferred.

The silicone-based surfactant is not particularly limited and may be appropriately selected depending on the purpose, and preferably does not decompose even at a high pH. For example, side chain-modified polydimethylsiloxane, both-end modified polydimethylsiloxane, Examples include one-end-modified polydimethylsiloxane, side-chain both-end-modified polydimethylsiloxane, and those having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as a modifying group exhibit good properties as an aqueous surfactant. Particularly preferred.
As such a surfactant, an appropriately synthesized product or a commercially available product may be used.
Such commercially available products can be easily obtained from, for example, Big Chemie Co., Ltd., Shin-Etsu Silicone Co., Ltd., Toray Dow Corning Silicone Co., Ltd.

  The polyether-modified silicone surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a compound in which a polyalkylene oxide structure is introduced into the Si part side chain of dimethylpolysiloxane, etc. Can be mentioned.

  A commercial item can be used as said polyether modified silicone compound, for example, KF-618, KF-642, KF643 (all are Shin-Etsu Chemical Co., Ltd. product) etc. are mentioned.

  In addition to the fluorine surfactant and the silicone surfactant, an anionic surfactant, a nonionic surfactant, an amphoteric surfactant, and the like can be used.

  In addition, penetrants, pH adjusters, antiseptic / antifungal agents, antifoaming agents, and the like are added to the ink depending on the purpose.

[Reduction of moisture in recording paper and drying means after printing]
As specifically shown in FIG. 2, an apparatus for heating the recording paper includes, for example, a method of applying microwave energy to the paper using microwave energy, an infrared heater, or a heating roller. As a mounting position, for example, a heating means (for example, a roller) is attached to a paper feeding roller portion of a paper feeding tray of the printer, or a heating means (for example, an infrared heater or microwave) is heated at the leading end of the paper feeding tray. In this case, the entire paper feed tray may be heated. The heating means attached to the paper feed roller portion of the paper feed tray is effective when the paper is dried only before printing. In order to dry the paper after printing, the paper after printing is returned to the paper feed tray.
When duplex printing is performed by the duplex feeding unit, heating means (heating unit) such as a microwave, an infrared heater, and a heating roller are provided at the position of the leading end of the feeding tray. Since it is close to the head, it is necessary to devise measures to suppress the influence of printing due to heating. In this case, after the paper heated and dried by the heating means is printed on one side, the paper is moved to the duplex unit by the reverse operation of the conveyor belt. At that time, the printed surface is dried. In this case, since it is necessary to dry a large amount of moisture in the ink, it is preferable to have a fan for generating an air flow for exhausting moisture and a duct portion for maintaining an exhaust route.
At the duplex unit, the paper is reversed and the back surface becomes the printing surface, and after drying again by the heating means, it comes to the head portion and prints on the back surface.

  FIG. 11 shows an example of the dry air flow guiding means in the present invention. The dry airflow guiding means of this example includes a cover member that surrounds a heat source (in this example, an infrared heater) and a reflector plate provided behind the heat source, and a hole-shaped (slit-shaped) airflow introducing portion provided in the cover member. And a partition wall having an opening, and an airflow discharger (a ventilation duct in this example). As shown in the figure, when using an infrared heater, for example, the infrared heater section and the paper are separated by a partition so that the paper does not burn. The printed surface is dried by both the radiant heat of the infrared heater and the heated and dried air by the flow of heated and dried air as shown in the figure.

[Ink flying process and ink flying means]
The ink flying step is a step of recording an image by applying a stimulus to the recording ink of the present invention and causing the recording ink to fly.
The ink flying means is means for recording an image by applying a stimulus to the recording ink of the present invention and causing the recording ink to fly. The ink flying means is not particularly limited, and examples thereof include various nozzles for ejecting ink.
In the present invention, it is preferable that at least a part of the liquid chamber portion, the fluid resistance portion, the vibration plate, and the nozzle member of the ink jet head is formed of a material containing at least one of silicon and nickel.
The nozzle diameter of the inkjet nozzle is preferably 30 μm or less, and preferably 1 to 20 μm.
In addition, it is preferable that a sub tank for supplying ink is provided on the ink jet head, and the sub tank is replenished with ink from an ink cartridge through a supply tube.

The stimulus can be generated, for example, by the stimulus generating means, and the stimulus is not particularly limited and can be appropriately selected according to the purpose, such as heat (temperature), pressure, vibration, light, etc. Is mentioned. These may be used individually by 1 type and may use 2 or more types together. Among these, heat and pressure are preferable.
Examples of the stimulus generating means include a heating device, a pressurizing device, a piezoelectric element, a vibration generating device, an ultrasonic oscillator, a light, and the like. Specifically, for example, a piezoelectric actuator such as a piezoelectric element, heat generation, etc. Examples include a thermal actuator that uses a phase change caused by film boiling of a liquid using an electrothermal transducer such as a resistor, a shape memory alloy actuator that uses a metal phase change caused by a temperature change, and an electrostatic actuator that uses an electrostatic force.

  There are no particular restrictions on the manner in which the recording ink flies, and it varies depending on the type of the stimulus. For example, when the stimulus is “heat”, a recording signal is output to the recording ink in the recording head. Corresponding thermal energy is applied using, for example, a thermal head, bubbles are generated in the recording ink by the thermal energy, and the recording ink is formed into droplets from the nozzle holes of the recording head by the pressure of the bubbles. For example, a discharge injection method may be used. Further, when the stimulus is “pressure”, for example, by applying a voltage to a piezoelectric element bonded to a position called a pressure chamber in an ink flow path in the recording head, the piezoelectric element bends and the volume of the pressure chamber is increased. And the recording ink is ejected and ejected as droplets from the nozzle holes of the recording head.

The size of the recording ink droplets to be ejected is preferably 2 to 40 pl, the ejection speed is preferably 6 to 20 m / s, and the driving frequency is preferably 1 kHz or more. The resolution is preferably 300 dpi or more.
In addition, it is preferable that ink is ejected to either the print area or the non-print area before moisture evaporation near the nozzle exceeds 30%.

  The control means is not particularly limited as long as the movement of each means can be controlled, and can be appropriately selected according to the purpose. Examples thereof include devices such as sequencers and computers.

One embodiment for carrying out the ink jet recording method of the present invention by the ink jet recording apparatus of the present invention will be described with reference to the drawings.
The ink jet recording apparatus shown in FIG. 1 has an apparatus main body (101), a paper feed tray (102) for loading paper mounted on the apparatus main body (101), and an image mounted on the apparatus main body (101). A paper discharge tray (103) for stocking (formed) paper and an ink cartridge loading section (104) are provided. Using this paper feed tray (102), it was possible to feed plastic sheets such as polyester sheets.
On the upper surface of the ink cartridge loading section (104), an operation section (105) such as operation keys and a display is arranged. The ink cartridge loading section (104) has an openable / closable front cover (112) for attaching and detaching the ink cartridge (200).

As shown in FIGS. 2 and 3, the apparatus main body (101) includes a guide rod (131), which is a guide member horizontally mounted on left and right side plates (not shown), and a stay (132). 133) is slidably held in the main scanning direction, and is moved and scanned in the direction of the arrow in FIG. 3 by a main scanning motor (not shown).
Reference numeral (A) in FIG. 2 shows an example of moisture reducing means for recording paper in the present invention. In this example, the attachment position of the moisture lowering means (A) is the paper feed roller (143) portion of the paper feed tray. In the present invention, when duplex printing is performed by the duplex feeding unit, for example, the heating means (B) can be provided at the position of the transport roller (157). Since the position is close to the head, as described above with reference to FIG. 11, a device for suppressing the influence of printing due to heating, for example, a dry air flow guiding means, is necessary. After printing on one side of the paper that has been heat-dried by the heating means (B), the paper moves to the duplex unit by the reverse operation of the conveyor belt.

The carriage (133) includes a recording head (134) including four inkjet recording heads that eject recording ink droplets of each color of yellow (Y), cyan (C), magenta (M), and black (Bk). Are arranged in a direction crossing the main scanning direction and the ink droplet discharge direction is directed downward.
As an inkjet recording head constituting the recording head (134), a piezoelectric actuator such as a piezoelectric element, a thermal actuator that utilizes a phase change caused by liquid film boiling using an electrothermal transducer such as a heating resistor, and a temperature change A shape memory alloy actuator using a metal phase change, an electrostatic actuator using an electrostatic force, or the like provided as an energy generating means for discharging recording ink can be used.
The carriage (133) is equipped with a sub tank (135) for each color for supplying ink of each color to the recording head (134). The sub-tank (135) is supplied with the recording ink of the present invention from the ink cartridge (200) of the present invention loaded in the ink cartridge loading section (104) via a recording ink supply tube (not shown). Is done.

  On the other hand, as a paper feeding unit for feeding the paper (142) stacked on the paper stacking unit (pressure plate) (141) of the paper feed tray (102), 1 sheet (142) is fed from the paper stacking unit (141). A half-moon roller (sheet feeding roller (143)) that separates and feeds one sheet at a time, and a sheet separation roller (144) made of a material having a large coefficient of friction, facing the sheet feeding roller (143), and this separation pad (144) It is biased toward the paper feed roller (143).

  A conveying belt (151) for electrostatically adsorbing and conveying the paper (142) as a conveying unit for conveying the paper (142) fed from the paper feeding unit below the recording head (134). A counter roller (152) for conveying the paper (142) sent from the paper supply unit via the guide (145) between the conveying belt (151) and a paper (substantially vertically upward) ( 142) and a leading guide roller 153 urged toward the conveying belt (151) by the holding member (154). (155) and a charging roller (156) which is a charging means for charging the surface of the conveyor belt (151).

The conveyance belt (151) is an endless belt, is stretched between the conveyance roller (157) and the tension roller (158), and can circulate in the belt conveyance direction. The transport belt (151) includes, for example, a surface layer serving as a sheet adsorbing surface formed of a resin material having a thickness of about 40 μm that is not subjected to resistance control, for example, a copolymer of tetrafluoroethylene and ethylene (ETFE), It has the same material as the surface layer and a back layer (medium resistance layer, earth layer) that has been subjected to resistance control by carbon. On the back side of the conveyance belt (151), a guide member (161) is arranged corresponding to the printing area by the recording head (134). As a paper discharge unit for discharging the paper (142) recorded by the recording head (134), a separation claw (171) for separating the paper (142) from the transport belt (151), and paper discharge A roller (172) and a paper discharge roller (173) are provided, and a paper discharge tray (103) is arranged below the paper discharge roller (172).
A double-sided paper feeding unit (181) is detachably attached to the back surface of the apparatus main body (101). The double-sided paper feeding unit (181) takes in the paper (142) returned by the reverse rotation of the transport belt (151), reverses it, and feeds it again between the counter roller (152) and the transport belt (151). . A manual paper feed unit (182) is provided on the upper surface of the double-sided paper feed unit (181).

In this ink jet recording apparatus, the sheet (142) is separated and fed one by one from the sheet feeding unit, and the sheet (142) fed substantially vertically upward is guided by the guide (145) and the transport belt (151). ) And the counter roller (152). Further, the leading end is guided by the conveying guide (153) and pressed against the conveying belt (151) by the leading end pressure roller (155), and the conveying direction is changed by about 90 °.
At this time, the conveyance belt (157) is charged by the charging roller (156), and the paper (142) is electrostatically adsorbed to the conveyance belt (151) and conveyed. Therefore, by driving the recording head (134) according to the image signal while moving the carriage (133), ink droplets are ejected onto the stopped sheet (142) to record one line, and the sheet ( 142) is carried a predetermined amount, and then the next line is recorded. Upon receiving a recording end signal or a signal that the rear end of the paper (142) has reached the recording area, the recording operation is finished and the paper (142) is discharged to the paper discharge tray (103).
When the recording ink remaining amount near end in the sub tank (135) is detected, a required amount of recording ink is supplied from the ink cartridge (200) to the sub tank (135).

  In this ink jet recording apparatus, when the recording ink in the ink cartridge (200) of the present invention is used up, the casing of the ink cartridge (200) can be disassembled and only the ink bag inside can be replaced. Further, the ink cartridge (200) can supply recording ink stably even when the ink cartridge (200) is vertically placed and has a front loading configuration. Therefore, even when the upper part of the apparatus main body (101) is closed and installed, for example, even when it is stored in a rack or an object is placed on the upper surface of the apparatus main body (101), the ink The cartridge (200) can be easily replaced.

Here, an example is described in which the present invention is applied to a serial (shuttle type) ink jet recording apparatus that is scanned by a carriage, but the present invention can be similarly applied to a line type ink jet recording apparatus having a line type head.
Further, the ink jet recording apparatus and the ink jet recording method of the present invention can be applied to various types of recording by the ink jet recording method. For example, the ink jet recording apparatus, the facsimile apparatus, the copying apparatus, the printer / fax / copier multifunction machine, etc. It can be particularly preferably applied.

The heating device in the present invention may be provided in the main body, or may be provided separately from the main body.
When provided in the main body, a heater may be provided so as to heat the inside of the paper feed tray (102).
The heater may be a non-contact type that applies microwave energy to paper using microwave energy. Further, a contact type (for example, a heating roller) may be provided separately. Note that the image sample after single-sided printing may be heated in the same manner, and then double-sided copying may be performed. In the case of double-sided copying, the printed paper tray (103) may be heated to dry the printed image, and may be passed directly to the double-sided paper feeding unit (181).

  Such a heating apparatus heats the recording paper medium in the present invention to 45 ° C. to 300 ° C. for 0.03 sec to 20 min (in the case of a contact type, 0.03 sec to 10 min, preferably 0.05 sec to 45 ° C. to 110 ° C.). It may be heated for 2 minutes, and in the case of a non-contact type, it may be heated at 50 ° C. to 300 ° C. for 0.5 sec to 20 min, preferably 0.05 sec to 10 min).

  In the present invention, the moisture reducing means (heating means) in advance of the recording paper medium and the drying means of the recording medium after printing may be the same, and in that case, the recording paper medium The transfer path can be divided into a transfer path for guiding to the delivery tray and a transfer path for returning to the original drying means entrance position, and has a transfer path switching edge at the branch point. In addition, it is not essential that the recording paper medium can be conveyed forward and backward by rotating the drive roller forward and backward.

(Production Example 1)
Preparation of ink-Preparation of polymer solution A-
After sufficiently replacing the inside of a 1 L flask equipped with a mechanical stirrer, thermometer, nitrogen gas introduction tube, reflux tube, and dropping funnel, 11.2 g of styrene, 2.8 g of acrylic acid, 12.0 g of lauryl methacrylate Then, 4.0 g of polyethylene glycol methacrylate, 4.0 g of styrene macromer, and 0.4 g of mercaptoethanol were mixed and heated to 65 ° C.
Next, 100.8 g of styrene, 25.2 g of acrylic acid, 108.0 g of lauryl methacrylate, 36.0 g of polyethylene glycol methacrylate, 60.0 g of hydroxylethyl methacrylate, 36.0 g of styrene macromer, 3.6 g of mercaptoethanol, azobismethylvalero A mixed solution of 2.4 g of nitrile and 18 g of methyl ethyl ketone was dropped into the flask over 2.5 hours. After dropping, a mixed solution of 0.8 g of azobismethylvaleronitrile and 18 g of methyl ethyl ketone was dropped into the flask over 0.5 hours. After aging at 65 ° C. for 1 hour, 0.8 g of azobismethylvaleronitrile was added and further aging was performed for 1 hour. After completion of the reaction, 364 g of methyl ethyl ketone was added to the flask to prepare 800 g of polymer solution A having a concentration of 50% by mass.

-Preparation of dimethylquinacridone pigment-containing polymer fine particle water dispersion-
Next, 28 g of the obtained polymer solution A, C.I. I. 42 g of CI Pigment Red 122, 13.6 g of a 1 mol / L potassium hydroxide aqueous solution, 20 g of methyl ethyl ketone, and 13.6 g of ion-exchanged water were sufficiently stirred, and then kneaded using a roll mill. The obtained paste was put into 200 g of pure water and sufficiently stirred, and then the methyl ethyl ketone and water were distilled off using an evaporator, and the magenta polymer fine particles of Production Example 1 containing 15% by mass of pigment and 20% by mass of solid were prepared. An aqueous dispersion was prepared.

(Production Example 2)
-Preparation of copper phthalocyanine pigment-containing polymer fine particle dispersion-
In Production Example 1, C.I. I. An aqueous dispersion of cyan polymer fine particles was prepared in the same manner as in Production Example 1 except that Pigment Red 122 was changed to a copper phthalocyanine pigment and the pigment was further changed to 12% and 20% by mass.

(Production Example 3)
-Preparation of monoazo yellow pigment-containing polymer fine particle dispersion-
In Production Example 1, C.I. I. An aqueous dispersion of yellow polymer fine particles was prepared in the same manner as in Production Example 1 except that Pigment Red 122 was changed to Pigment Pigment Yellow 74 and the pigment content was 12% and the solid content was 20% by mass.

(Production Example 4)
-Preparation of polymer fine particle dispersion B (acrylic silicone emulsion)-
After fully replacing the inside of a 1 L flask equipped with a mechanical stirrer, thermometer, nitrogen gas inlet tube, reflux tube, and dropping funnel, 8.0 g of Latemul S-180 and 350 g of ion exchange water were added and mixed. The temperature was raised to 65 ° C. After temperature increase, 3.0 g of reaction initiator t-butyl peroxobenzoate and 1.0 g of sodium isoascorbate were added, and after 5 minutes, 45 g of methyl methacrylate, 160 g of 2-ethylhexyl methacrylate, 5 g of acrylic acid, butyl methacrylate 45 g, 30 g of cyclohexyl methacrylate, 15 g of vinyltriethoxysilane, 8.0 g of Latemul S-180, and 340 g of ion-exchanged water were mixed and dropped over 3 hours. Then, after heat aging at 80 ° C. for 2 hours, the mixture was cooled to room temperature and the pH was adjusted to 7-8 with sodium hydroxide. Ethanol was distilled off using an evaporator and the water content was adjusted to prepare 730 g of the polymer dispersion B solution of Production Example 4 having a solid content of 40% by mass. The particle size of the resin fine particles was approximately 130 nm (measured at 23 ° C.). The particle size was measured using a particle size distribution measuring device UPA150 manufactured by Microtrack Co., Ltd. at a dilution ratio of 500 times.

  Next, the effects of the above-described embodiment will be described below using examples.

(Example 1)
The recording ink was produced according to the following procedure.
<Ink Example 1-1>
Magenta ink having the following formulation Magenta pigment-containing polymer fine particle dispersion of Production Example 1 (solid content 20%) 38% by mass
Emulsion resin aqueous solution of Production Example 4 (concentrated to a solid content of 55%) 36% by mass
1,3-butanediol 19.5% by mass
Glycerin 6% by mass
2-ethyl-1,3-hexanediol 1% by mass
Fluorine-based surfactant (FS-300 manufactured by DuPont) 2% by mass
Antiseptic and fungicidal agent (Zeneca Proxel LV) 0.05% by mass
Amine-based pH adjuster 0.6% by mass
Silicone defoamer 0.1% by mass
Residual water Viscosity: 12.3 m · Pas, surface tension: 25.1 mN / m, total solids: 26%, electrical conductivity 487 μS / cm

<Ink Example 1-2>
The following cyan ink The cyan dispersion of Production Example 2 was used instead of the magenta dispersion of Example 1-1.
Viscosity: 12.54 mPas, surface tension 25.1 mN / m, total solid content 26%, electrical conductivity 587 μS / cm

<Ink Example 1-3>
The following yellow ink The yellow dispersion of Production Example 3 was used in place of the magenta dispersion of Example 1-1.
Viscosity: 15.24 mPas, surface tension 25.2 mN / m, total solid content 26%, electric conductivity 550 μS / cm

[Recording paper media example 1]
The paper used was Oji Paper Co., Ltd. POD gloss coat 100 g / m ² paper. The amount of transfer of pure water to a recording medium at a contact time of 100 ms measured with a dynamic scanning absorption meter of this paper is 3.1 ml / m ² and the transfer of pure water to a recording medium at a contact time of 400 ms. The amount was 3.5 ml / m ² .
This paper was put into a dryer at 65 ° C. and several percent humidity and dried for 5 minutes. Thereafter, printing was performed with a Ricoh manufactured inkjet printer G-707. The printing environment is 23 ° C. and 50% humidity. It took 45 seconds to remove from the dryer and print. A 1 cm square green solid was printed. The ink adhesion amount is approximately 15.5 g / m ² . Advantech filter paper 5A was pressed against this, and the drying property was observed by the amount of ink transferred to the filter paper (referred to as filter paper adhesion drying test).
Almost no adhesion to the filter paper in about 40 seconds after printing. The image also had little density unevenness.

(Comparative Example 1)
The same test as in Example 1 was performed, except that the 60 ° C. environment was not dried. In this case, in the filter paper adhesion drying test, it was not easy to dry even after 90 seconds (transferred to the filter paper). Density unevenness appeared clearly.

(Example 2)
Printing was performed at an ink adhesion amount of 8.5 g / m ² in the same manner as in Example 1. Almost no adhesion to the filter paper in 10 seconds.

(Comparative Example 2)
A test similar to that of Example 2 was performed, except that the 60 ° C. environment was not dried. In this case, it did not readily dry even after 30 seconds in the filter paper adhesion drying test.

Providing the drying step before printing in this way has an effect on the filter paper adhesion drying property at the time of printing.
Ink-jet drying is generally referred to as osmotic drying. In this case, drying before printing seems to reduce the amount of water in the paper. This seems to have accelerated the ink penetration during ink printing.
FIG. 4 shows the weight of the paper before drying and the weight change (moisture recovery) when the paper is dried for 5 minutes in a humidity environment of 60 ° C. and several percent and then returned to normal temperature and humidity.
FIG. 5 is a conversion of the moisture recovery rate. About 3% of gloss paper is 40% in 1 minute and 90% in 5 minutes after drying with moisture.
6 and 7 show the drying time, the weight change in the paper due to drying, and the moisture remaining rate.
It can be seen that the drying time (60 ° C. (several% RH) environment) is 80% evaporation of the equilibrium moisture content of the paper in 1 minute, 90% in 5 minutes, and 100% in 10 minutes.
From this examination result, the equilibrium moisture content in the paper at 23 ° C. and 50% humidity was about 3.6% by mass.
In general, this glossy paper is saturated at an adhesion amount of about 10 g / m ^{2 at the time} of ink printing at 23 ° C. and a humidity of 50%, and it is difficult for the paper to penetrate. Approximately 1 / 2.5 of that amount of water is already present in the paper before printing. Therefore, removing this in advance in the drying step increases the filter paper adhesion drying property.

8 and 9 show the drying time at 60 ° C. and the weight change and moisture recovery rate when the temperature is returned to 23 ° C. and 50% humidity after drying.
Although the drying amount varies depending on the drying time within 10 minutes, the moisture recovery is similar. Therefore, if the drying time is 1 minute or more, after drying, the humidity is restored to 50% at 23 ° C., and 40% of water is recovered in about 1 minute and 90% of water is recovered in 5 minutes.
As a result of actual experiments, in order for the filter paper adhesion drying property and image density unevenness during printing to be in a practical range, the water content is approximately 75% or less, preferably 50% or less of the water content at equilibrium. There was a need.
FIG. 10 shows the difference in the moisture remaining rate with a drying time of 10 minutes depending on the drying temperature.
A drying temperature of 50 ° C. or higher is required to achieve a moisture residual rate of 40% or less within a drying time of 10 minutes.
A drying temperature of 60 ° C. is required to make the residual moisture rate 40% or less within 1 minute.

The recording medium has a support and a coating layer on at least one surface of the support, and the recording medium is pure water at a contact time of 100 ms measured with a dynamic scanning absorptiometer. a transition amount 2~35ml / ^{m 2,} and a paper transfer amount of said to the recording medium of pure water at the contacting time 400ms is 3~40ml / ^{m 2} is, image despite good, dry Although it was inferior in properties, it became dry enough to withstand high-speed printing by providing the drying step of the present invention. Further, as the ink, an ink having a low surface tension by adding a silicon-based or fluorine-based surfactant was suitable as a high-speed drying ink in combination with this drying step. Without such a surfactant, there is an effect of heat drying, but it is insufficient.
On the other hand, when the paper thus heated is printed by a machine that adsorbs the paper to a belt that is charged by the paper conveyance method, like the machine used in the present invention, the generated mist is charged and returned to the head surface, There was a phenomenon where it accumulated and nozzles were missing. In particular, this tendency was observed in dye inks (3,000 to 5000 μS / cm) having an electric conductivity of 2000 μS / cm or more.
In combination with the heating method and the charging belt conveyance method, the ink preferably had an electric conductivity of 2000 μS / cm or less.
In addition, when performing double-sided printing on such paper, it is necessary to quickly heat the sample after printing. In this case, the paper output tray (103) may be heated to dry the printed image, and may be directly rotated to the duplex paper supply unit (181).

It is the schematic for enforcing the inkjet recording method of this invention. It is a side view for enforcing the ink jet recording method of the present invention. It is another side view for enforcing the ink jet recording method of the present invention. It is the figure which showed the weight change (moisture recovery | restoration) of the paper at the time of returning to normal temperature and normal humidity after drying for 5 minutes in a 60 degreeC several percent humidity environment, and the weight of the paper before drying. It is the figure which converted FIG. 4 into the moisture recovery rate. It is the figure which showed the weight change in paper by drying time and drying. It is the figure which showed the moisture remaining rate in the paper by drying time and drying. It is the figure which showed the weight change when it returns to 50% of 23 degreeC humidity after drying time and 60 degreeC. It is the figure which showed the moisture recovery rate when it returns to 50% of 23 degreeC humidity after drying time and 60 degreeC. It is the figure which showed the difference by the drying temperature of the moisture residual rate in 10 minutes of drying time. It is an example of the dry airflow guidance means in this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Main body 102 Paper feed tray 103 Paper discharge tray 104 Ink cartridge loading part 105 Operation part 111 Upper cover (top plate)
112 Front cover 131 Guide rod 132 Stay 133 Carriage 134 Recording head 135 Sub tank 141 Paper stacking unit 142 Paper 143 Paper feed roller 144 Separation pad 145 Guide 151 Conveying belt 152 Counter roller 153 Conveying guide 154 Pressing member 155 Tip pressure roller 156 Charging roller 157 Conveying roller 158 Tension roller 161 Guide member 171 Separation claw 172 Paper discharge roller 173 Paper discharge roller 181 Double-sided paper feed unit 182 Manual paper feed unit 200 Ink cartridge A Example of recording paper moisture lowering means B Heating means

Claims (10)

An ink jet recording method, comprising: performing ink jet recording on a recording medium in which a moisture content of a recording medium, which is a paper medium, is previously set to be equal to or less than an equilibrium moisture content at a temperature and humidity at the time of printing. An operation for forcing the recording paper medium to be equal to or less than the equilibrium water content at the temperature and humidity at the time of printing in advance and an operation for performing inkjet printing on the recording medium after the operation is performed. Item 10. The ink jet recording method according to Item 1. The inkjet recording method according to claim 2, further comprising a drying operation for drying the recording medium after printing. The recording medium comprises a support and a coating layer on at least one surface of the support, and pure water is applied to the recording medium at a contact time of 100 ms measured with a dynamic scanning absorptiometer. transfer amount is 2~35ml / ^{m 2,} and the contact time the ink-jet recording according to any one of claims 1 to 3 transfer amount of said to the recording medium of the pure water is 3~40ml / ^{m 2} at 400ms Method. 2. Printing is carried out with the moisture content in the paper being 75% by mass or less, preferably 50% by mass or less of the equilibrium moisture content of the temperature and humidity during printing (usually normal temperature and normal humidity—23 ° C. and 50 RH%). 5. The ink jet recording method according to any one of 4 to 4. 6. The ink jet recording method according to claim 1, wherein the forced drying operation of the recording medium is a heating operation, and printing is performed within 1 minute after the heating. Characterized in that it has a moisture reducing means that makes the recording paper medium equal to or less than the equilibrium moisture content at the temperature and humidity at the time of printing, and a printing means for inkjet printing on the recording medium after passing through the moisture reducing means. Inkjet recording apparatus. The inkjet recording apparatus according to claim 7, further comprising a drying unit for drying the recording medium after printing. An ink for ink jet recording for ink jet printing, wherein the recording paper medium conveying method for ink jet printing is to adsorb the paper electrostatically to a charged belt, and the recording paper medium has a moisture content. An ink for ink-jet recording, which is ink-jet-printed in a state where the amount of water is equal to or less than the equilibrium water content at temperature and humidity during recording, and has an electric conductivity of 2000 μS / cm or less. 10. The ink jet recording according to claim 9, comprising at least a colorant, a water-dispersible resin, a wetting agent, a surfactant, and water, and the surfactant is a silicon-based or fluorine-based surfactant. For ink.

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