JP2007160839A - Inkjet recording method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inkjet recording method having high image quality and good surface drying property without curling problem and without turbulence of an image due to lack of nozzle because of high density. <P>SOLUTION: In the inkjet recording method using an inkjet ink containing at least water, the water-soluble organic solvents and pigments and having 10 to 50 mass% of water content to whole ink mass and in which SP value of the water-soluble organic solvent present most in the ink of the water-soluble organic solvents is 16.5 or more and less than 24.6 and the content of the water-soluble organic solvents whose SP value is 16.5 or more and less than 24.6 is 30 mass% or more and less 90 mass% to whole ink mass, the paper surface is forcibly dried during 0 s to 3 s after the ink is shot. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an inkjet recording method capable of high-quality double-sided printing.

  In recent years, the inkjet recording method can easily and inexpensively create an image, and thus has been applied to various printing fields such as photographs, various printing, marking, and special printing such as a color filter. In particular, ink jet recording devices that emit and control fine dots, ink with improved color reproduction range, durability, and emission suitability, ink absorbency, colorant color development, surface gloss, etc. are dramatically improved. It is also possible to obtain image quality comparable to silver halide photography using special paper.

  However, in an inkjet image recording system that requires dedicated paper, there are problems in that the recording media that can be used are limited and the cost of the recording media is increased.

  On the other hand, in the office, there is an increasing need for a system capable of performing full color printing at high speed without being restricted by a recording medium (for example, plain paper, coated paper, art paper, plain paper double-sided printing, etc.).

  As for the composition of the ink-jet ink, it can be printed at high speed, has good character reproducibility on plain paper, and shows through when printing (the phenomenon that the printed ink passes through the recording medium and the image appears on the back), feathering Various studies have been made from the viewpoints of no occurrence of image bleeding, rapid penetration into paper, and quick drying. In the case of a print form in consideration of high-speed printing in which 10 or more A4 sheets are printed per second, emission by a line head is essential.

  Unlike a shuttle-type head, a print system using a line head cannot perform interleaving. Therefore, if a nozzle shortage occurs, the image quality is greatly degraded. In particular, in the case of solid printing, if a nozzle shortage occurs even at one place, the line will be lost, and the line head is required to have very good injection stability.

  In high-speed printing, in the case of a print form, the printed material is superimposed immediately after printing, and the ink of the lower paper is reflected on the back surface of the upper paper, so that the surface drying property of the ink is required.

  If an ink that uses a liquid with a high vapor pressure as a solvent is selected as the ink with a high surface drying property, the ink transfer due to the overlap of printed matter can be suppressed, but the head maintenance and output stability will be impaired. It is not suitable for high-speed printing applications such as heads that require emission stability.

  Japanese Patent Laid-Open No. 10-316915 discloses a method for achieving both high output stability and surface drying by improving the surface drying by increasing the permeability of ink into paper and realizing high-speed printing. It is disclosed.

  However, in this method, since the colorant in the ink also penetrates into the plain paper at the same time, the image density is lowered and the ink shows through, which is not suitable for double-sided printing. Have

  Further, for example, Patent Document 1 discloses a method of providing a drying means as a means for improving the surface drying property of a printed matter. According to the method disclosed in Japanese Patent Application Laid-Open No. H10-228707, even if the ink has a slow drying property, it can be dried in a short time by drying with infrared rays, and high-speed printing can be achieved.

However, the above method has a problem that significant curling occurs due to drying. On the other hand, Patent Documents 3 and 4 disclose a method of providing a mechanism for correcting curling caused by drying. However, these methods require time for correcting the curl and increase the apparatus. Since this happens, the cost burden is large.
JP 63-252772 A JP 63-252772 A JP 2001-301151 A JP 2002-187264 A

  In the above problems, surface dryness and compatibility between curl and surface concentration are also problems.

  An object of the present invention is to provide an ink jet recording method having high image quality and good surface dryness because there is no problem with curling and there is no image disturbance due to lack of nozzles at a high density.

  The above object of the present invention is achieved by the following configurations.

  1. A water-soluble organic solvent containing at least water, a water-soluble organic solvent and a pigment, wherein the water content is less than 10 to 50% by mass of the total ink mass, and the water-soluble organic solvent is the most contained among the water-soluble organic solvents. The SP value is 16.5 or more and less than 24.6, and the content of the water-soluble organic solvent having the SP value of 16.5 or more and less than 24.6 is 30% by mass or more and less than 90% by mass of the total ink mass. An ink jet recording method using an ink, wherein the paper is forcibly dried between 0 s and 3 s after landing of the ink.

  2. A water-soluble organic solvent containing at least water, a water-soluble organic solvent, and a pigment, wherein the water content is less than 10 to 50% by mass of the total ink mass, and the water-soluble organic solvent is the most contained among the water-soluble organic solvents. The SP value is 16.5 or more and less than 24.6, and the content of the water-soluble organic solvent having the SP value of 16.5 or more and less than 24.6 is 30% by mass or more and less than 90% by mass of the total ink mass. An ink jet recording method using an ink, wherein air is blown on a paper surface between 0 s and 3 s after ink landing.

  3. A water-soluble organic solvent containing at least water, a water-soluble organic solvent, and a pigment, wherein the water content is less than 10 to 50% by mass of the total ink mass, and the water-soluble organic solvent is the most contained among the water-soluble organic solvents. The SP value is 16.5 or more and less than 24.6, and the content of the water-soluble organic solvent having the SP value of 16.5 or more and less than 24.6 is 30% by mass or more and less than 90% by mass of the total ink mass. An ink jet recording method using an ink as described above, wherein infrared irradiation is applied to a paper surface between 0 s and 3 s after ink landing.

  That is, the present inventors have no problem with curling, there is no image disturbance due to lack of nozzles at a high density, and the effect of emission stability that can perform ink jet printing with good surface drying is mainly due to ink. Since the ink composition contains a large amount of a water-soluble organic solvent having a higher hydrophobicity than water, the solubility of the entire ink is high, and as a result, cavitation is unlikely to occur during continuous emission. Therefore, the emission stability is high even in high-speed emission from a line head or the like.

  Also, curl is good because the ratio of the hydrophobic solvent in the ink is high. Further, by performing drying, the surface can be further dried and the concentration can be improved. The effect of density improvement is that the pigment atmosphere is induced by changing the solvent atmosphere by drying the solvent immediately after printing and before the pigment is fixed to the cellulose, and evaporating the solvent having a low vapor pressure. Estimated.

  In addition, the present inventors pay attention to the time until the pigment is fixed on the cellulose, and as a result of intensive studies, the inventors have found that within 3 seconds is effective for the ink of the present invention.

  Furthermore, an ink that satisfies the requirements of the present invention not only has a lower degree of swelling of paper but also a slower speed of swelling than an ink with a high water ratio. For this reason, when drying is performed at an extremely early stage, it is presumed that curling and cockling are improved because drying in a solvent is performed before the swelling of paper reaches parallel.

  On the other hand, since the paper fiber swells quickly in the ink containing water as the main solvent, curling and cockling are improved by performing the drying described in JP-A Nos. 2001-301151 and 2002-187264. On the contrary, the curl gets worse.

  The ink jet recording method according to the present invention has an excellent effect of high image quality and good surface dryness because there is no problem in curling, and there is no image disturbance due to a lack of nozzles at a high density.

  Details of the present invention will be described below.

  First, the plain paper in the present invention will be described.

  Examples of the plain paper in the present invention include what are generally called high-quality paper, neutral paper, and copy paper. When a recording sheet or paper is used in the text, it means plain paper.

  Next, the ink used in the present invention will be described.

  The ink used in the present invention contains at least water, a water-soluble organic solvent, and a pigment. Here, the water-soluble organic solvent is not particularly limited as long as it can be mixed with water. Two or more water-soluble organic solvents can be used in combination. However, in order to suppress the occurrence of cavitation when continuously emitting light, the SP value of the most water-soluble organic solvent among the water-soluble organic solvents is 16.5 or more and less than 24.6, It is preferable that the content of the water-soluble organic solvent having an SP value of 16.5 or more and less than 24.6 is 30% by mass or more of the total ink mass. Since this solvent composition contains a large amount of a water-soluble organic solvent having a higher hydrophobicity than water, the solubility of the entire ink is high, and as a result, cavitation is unlikely to occur during continuous emission.

  The solvent solubility parameter (SP value) in the present invention is a value represented by the square root of the molecular cohesive energy. F. Fedors, Polymer Engineering Science, 14, p147 (1974). The unit is (MPa) 1/2, and refers to the value at 25 ° C.

  Hereinafter, examples of water-soluble organic solvents having an SP value of 16.5 or more and less than 24.6 are shown together with the SP value. Needless to say, the present invention is not limited to this.

Ethylene glycol monomethyl ether (SP value: 24.5)
Ethylene glycol monoethyl ether (23.5)
Ethylene glycol monobutyl ether (22.1)
Ethylene glycol monoisopropyl ether (22.3)
Diethylene glycol monomethyl ether (23.0)
Diethylene glycol monoethyl ether (22.4)
Diethylene glycol monobutyl ether (21.5)
Diethylene glycol diethyl ether (16.8)
Triethylene glycol monomethyl ether (22.1)
Triethylene glycol monoethyl ether (21.7)
Triethylene glycol monobutyl ether (21.1)
Propylene glycol monomethyl ether (23.0)
Propylene glycol monophenyl ether (24.2)
Dipropylene glycol monomethyl ether (21.3)
Tripropylene glycol monomethyl ether (20.4)
1,3-dimethyl-2-imidazolidinone (21.8)
In the ink used in the present invention, various conventionally known water-soluble organic solvents can be used in combination with a water-soluble organic solvent having an SP value of 16.5 or more and less than 24.6.

  Examples of water-soluble organic solvents preferably used as the solvent used in combination include alcohols (for example, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol, pentanol, hexanol, cyclohexane). Hexanol, benzyl alcohol, etc.), polyhydric alcohols (eg, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, Thiodiglycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanedio , 1,2-pentanediol, 1,2-hexanediol, 1,2,6-hexanetriol, etc.), amines (eg, ethanolamine, diethanolamine, triethanolamine, N-methyldiethanolamine, N-ethyldiethanolamine) , Morpholine, N-ethylmorpholine, ethylenediamine, diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine, etc.), amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.), heterocyclic rings (for example, 2-pyrrolidone, N-methyl-2-pyrrolidone, cyclohexylpyrrolidone, 2-oxazolidone, etc.), sulfoxides For example, dimethyl sulfoxide, etc.), sulfones (e.g., sulfolane), urea, acetonitrile, and acetone.

  As the pigment that can be used in the present invention, conventionally known pigments can be used without particular limitation, and any of water-dispersible pigments, solvent-dispersible pigments, and the like can be used, for example, organic pigments such as insoluble pigments and lake pigments, An inorganic pigment such as carbon black can be preferably used. This pigment is present in a dispersed state in the ink, and the dispersion method may be any of self-dispersion, dispersion using a surfactant, polymer dispersion, and microcapsule dispersion. Dispersion is particularly preferred from the standpoint of fixability.

  The insoluble pigment is not particularly limited. Dioxazine, thiazole, phthalocyanine, diketopyrrolopyrrole and the like are preferable.

  Specific pigments that can be preferably used include the following pigments.

  Examples of the magenta or red pigment include C.I. I. Pigment red 2, C.I. I. Pigment red 3, C.I. I. Pigment red 5, C.I. I. Pigment red 6, C.I. I. Pigment red 7, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 48: 1, C.I. I. Pigment red 53: 1, C.I. I. Pigment red 57: 1, C.I. I. Pigment red 122, C.I. I. Pigment red 123, C.I. I. Pigment red 139, C.I. I. Pigment red 144, C.I. I. Pigment red 149, C.I. I. Pigment red 166, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. Pigment red 202, C.I. I. Pigment red 222, C.I. I. Pigment violet 19 and the like.

  Examples of the pigment for orange or yellow include C.I. I. Pigment orange 31, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 12, C.I. I. Pigment yellow 13, C.I. I. Pigment yellow 14, C.I. I. Pigment yellow 15, C.I. I. Pigment yellow 15: 3, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 94, C.I. I. And CI Pigment Yellow 138.

  Examples of the pigment for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 16, C.I. I. Pigment blue 60, C.I. I. And CI Pigment Green 7.

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

  The average particle diameter of the dispersed state of the pigment contained in the inkjet ink of the present invention is preferably 50 nm or more and less than 200 nm. If the average particle size of the pigment dispersion is less than 50 nm or 200 nm or more, the stability of the pigment dispersion tends to be poor, and the storage stability of the ink tends to deteriorate.

  The particle size of the pigment dispersion can be determined by a commercially available particle size measuring instrument using a dynamic light scattering method, an electrophoresis method, or the like. Accurate and often used.

  The pigment used in the present invention is preferably used after being dispersed by a disperser together with a dispersant and other necessary additives according to desired purposes. As the disperser, a conventionally known ball mill, sand mill, line mill, high-pressure homogenizer, or the like can be used. In particular, the particle size distribution of the ink produced by dispersion with a sand mill is sharp and preferable. The material of the beads used for sand mill dispersion is preferably zirconia or zircon from the viewpoint of contamination of bead fragments and ionic components. Furthermore, the bead diameter is preferably 0.3 mm to 3 mm.

  In the ink used in the present invention, it is preferable to use a polymer dispersant in the dispersion.

  The polymer dispersant referred to in the present invention has a polymer component having a molecular weight of 5000 or more and 200000 or less. The polymer dispersant is selected from styrene, styrene derivatives, vinyl naphthalene derivatives, acrylic acid, acrylic acid derivatives, maleic acid, maleic acid derivatives, itaconic acid, itaconic acid derivatives, fumaric acid and fumaric acid derivatives. Examples thereof include a block copolymer comprising at least one kind of monomer, a random copolymer and salts thereof, polyoxyalkylene, and polyoxyalkylene alkyl ether.

  In the case of an acidic polymer dispersant, it is preferably added after neutralization with a neutralizing base. Here, the neutralizing base is not particularly limited, but is preferably an organic base such as ammonia, monoethanolamine, diethanolamine, triethanolamine, or morpholine.

  Moreover, in this invention, it is preferable that the addition amount of a polymer dispersing agent is 10-100 mass% with respect to a pigment.

  In the ink used in the present invention, in addition to the above description, according to the purpose of improving the emission stability, print head and ink cartridge compatibility, storage stability, image storage stability, and other various performances as necessary. Various known additives such as polysaccharides, viscosity modifiers, specific resistance regulators, film forming agents, ultraviolet absorbers, antioxidants, anti-fading agents, anti-fouling agents, rust inhibitors, etc. For example, oil droplet fine particles such as liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicone oil, ultraviolet absorption described in JP-A-57-74193, 57-78988 and 62-261476 Agent, JP-A-57-74192, JP-A-57-87989, JP-A-60-72785, JP-A-61-146591, JP-A-1-95091 and JP-A-3-1337. Fluorescent dyes described in JP-A-59-42993, JP-A-59-52689, JP-A-62-280069, JP-A-61-228771, JP-A-4-219266, etc. A brightener and the like can be mentioned.

  The ink used in the present invention having the above structure preferably has an ink surface tension of 25 to 40 mN / m at 25 ° C., more preferably 25 to 35 mN / m, still more preferably 30 to 30 mN / m. 35 mN / m. The ink viscosity is preferably 1 to 40 mPa · s at 25 ° C., more preferably 5 to 40 mPa · s, and still more preferably 5 to 20 mPa · s.

  Further, it is preferable to use a surfactant in order to accelerate the penetration of ink droplets after ink ejection into plain paper, and such a surfactant has an adverse effect on the ink, such as storage stability. The surfactant is not limited as long as it does not affect the surface, and the same surfactants as those used as an additive at the time of dispersion can be used.

  Further, in the ink used in the present invention, the total content of calcium ions, magnesium ions and iron ions, which are polyvalent metal ions of the ink, is preferably 10 ppm or less, more preferably 0.1 to 5 ppm. Especially preferably, it is 0.1-1 ppm.

  By setting the content of polyvalent metal ions in the inkjet ink to the amount specified above, an ink having high dispersion stability can be obtained. The polyvalent metal ion according to the present invention is contained in sulfates, chlorides, nitrates, acetates, organic ammonium salts, EDTA salts and the like.

  In the ink used in the present invention, in addition to the above description, if necessary, according to the purpose of improving the emission stability, print head and ink cartridge compatibility, storage stability, image storage stability, and other various performances, Various known additives such as polysaccharides, viscosity modifiers, specific resistance modifiers, film forming agents, ultraviolet absorbers, antioxidants, anti-fading agents, anti-fouling agents, rust preventives and the like are appropriately selected and used. For example, oil droplet fine particles such as liquid paraffin, dioctyl phthalate, tricresyl phosphate, silicone oil, and ultraviolet absorbers described in JP-A Nos. 57-74193, 57-87988 and 62-261476 JP-A-57-74192, JP-A-57-87989, JP-A-60-72785, JP-A-61-146591, JP-A-1-95091 and JP-A-3-1337. Fluorescent dyes described in JP-A-59-42993, JP-A-59-52689, JP-A-62-280069, JP-A-61-228771, JP-A-4-219266, etc. A brightener and the like can be mentioned.

  In the ink of the present invention having the above-described configuration, the surface tension of the ink is preferably 25 to 40 mN / m at 25 ° C., more preferably 25 to 35 mN / m, and further preferably 30 to 35 mN / m. It is. The ink viscosity is preferably 1 to 40 mPa · s at 25 ° C., more preferably 5 to 40 mPa · s, and still more preferably 5 to 15 mPa · s. In addition, the dissolved oxygen concentration in the ink of the present invention is preferably 2 ppm or less at 25 ° C. By setting this dissolved oxygen concentration condition, the formation of bubbles can be suppressed, and the emission stability even in high-speed printing. An ink jet recording method having excellent properties can be realized. As a method for measuring the dissolved oxygen dissolved in the ink, for example, it can be measured using a dissolved oxygen measuring device DO-14P (manufactured by Toa Radio).

  In the ink jet recording method of the present invention, for example, an ink jet print is obtained by ejecting ink as droplets from an ink jet head based on a digital signal and adhering it to plain paper by a printer loaded with ink jet ink.

  When an image is formed by ejecting the ink of the present invention, the inkjet head to be used may be an on-demand system or a continuous system. Also, as a discharge method, an electro-mechanical conversion method (for example, a single cavity type, a double cavity type, a bender type, a piston type, a shear mode type, a shared wall type, etc.), an electro-thermal conversion method (for example, thermal ink jet) Any ejection method such as a mold, a bubble jet (registered trademark) mold, or the like may be used.

  Among them, in the ink jet recording method of the present invention, the ink of the present invention is ejected from a piezo ink jet recording head having a nozzle diameter of 30 μm or less, recording is performed on plain paper, and the nozzle diameter is 30 μm or less. Recording is performed on plain paper by being ejected from a line head type inkjet recording head.

  When printing with a shuttle head type recording head as a printing method of an ink jet printer, drying within 3 s after printing, which is a feature of the present invention, is technically difficult. In practice, a line head type recording head is used. It is characterized by printing.

  The forced drying of the paper surface in the present invention means performing some drying means for speeding up the drying of the ink on the paper surface after printing.

  The drying means can be carried out by any method selected from known methods. For example, there are a method using heating and blowing, a method using irradiation of electromagnetic waves, and the like, and these methods may be used in combination.

  When the paper is dehumidified by heating or irradiation with electromagnetic waves, the surface temperature of the paper during drying is preferably in the range of 30 to 200 ° C. If it is 200 degrees C or less, there is little risk of ignition, and if it is 30 degrees C or more, since drying of paper is quick, it is preferable.

  When drying by irradiation with electromagnetic waves, it is preferable to use infrared rays or microwaves because high drying efficiency is exhibited in a short time. In the present invention, infrared refers to an electromagnetic wave having a wavelength in the range of 0.1 μm to 1 mm, and the effects of the present invention can be obtained by irradiation of either generally called far infrared or near infrared. Microwave refers to an electromagnetic wave having a wavelength in the range of 1 mm to 1 m.

  Irradiation of electromagnetic waves needs to be started within 3 s after ink landing. If it is slower than this, the pigment penetrates into the paper and at the same time begins to be fixed on the cellulose fiber as fine particles, so that the effect of the present invention cannot be expected. There is no problem in the early irradiation of the electromagnetic wave, and if there is no problem with the apparatus or the head, the landing position may be irradiated in advance.

  The electromagnetic wave to be irradiated preferably has a power of 200 to 800 W. When the power is 200 W or higher, vaporization of the organic solvent remaining in the recording medium is promoted. When the power exceeds 800 W, the irradiation conditions are severe and there is a risk of causing burns on the paper.

  The irradiation time varies depending on the energy and wavelength to be irradiated, the composition of the ink that has been applied, the conveyance speed, and the like, but irradiation for 0.1 seconds or more is preferable. When the irradiation time is 0.1 seconds or longer, it is possible to carry out in a range that falls within the preferable power and the preferable surface temperature. By extending the irradiation time, it is possible to sufficiently dry the solvent and obtain the effect described in Japanese Patent Application No. 2002-187264, but it is desirable that the irradiation time is within 10 s when high-speed printing is taken into consideration. it is conceivable that.

  In order to emit infrared radiation, it may be obtained directly from a heat source or through a heat medium to generate effective infrared radiation therefrom. For example, an infrared ray may be obtained by heating a discharge lamp such as mercury, xenon, cesium, or sodium, or a carbon dioxide laser, or an electric resistor such as platinum, tungsten, nichrome, or cantal. A specifically preferred apparatus is a halogen lamp. Halogen lamps have advantages such as good thermal efficiency and quick start-up.

  The infrared irradiation may be performed from the printing surface side or from the back surface side. It is also preferable to perform irradiation from both sides simultaneously. It is preferable to combine with temperature rising drying or ventilation drying. Further, it is more preferable to use a light collector if necessary.

  To obtain microwave radiation, known microwave generators such as klystrons, Gunn diodes, transistors, and magnetrons can be used. A magnetron is particularly preferable because of its small size and low cost.

  If necessary, it is preferable to provide an isolation wall for blocking microwaves.

  When performing drying by blowing air, it is more preferable to use dry air or heated air.

  The air drying needs to be started within 3 s of the ink landing. If it is slower than this, the pigment penetrates into the paper and at the same time begins to be fixed on the cellulose fiber as fine particles, so that the effect of the present invention cannot be expected.

  On the other hand, regarding the start of air blowing, if the nozzle for blowing and drying is close to the nozzle, the landing position of the ejected ink may be deviated, and therefore the air blown zone is separated by 2 cm or more as the distance along the transport mechanism. Is preferred. For this reason, it is preferable that the time for starting the blowing is after 0.001 seconds or more have elapsed after printing, assuming that printing is performed every 100 seconds in A4, for example.

  The time for blowing air varies depending on the temperature, humidity, ink composition, etc., but it is desirable to blow air for 0.5 s or more.

  The air may be blown directly on the paper surface or may be a method of drying and / or circulating hot air in the drying zone. At the same time, it is also preferable to heat the drying zone and the paper.

  Moreover, it is desirable to provide a windshield for controlling the flow of wind in the printer and in the air blowing zone as necessary.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, the embodiment of this invention is not limited to these.

Examples [Preparation of Pigment Dispersion A]
After mixing 15 parts by mass of MA100 as a pigment, 15 parts by mass of Jonkrill 501 as a dispersion resin, 5 parts by mass of TPGME, and 65 parts by mass of water, the mixture is placed in a polypropylene plastic bottle together with 200 parts by mass of zirconia beads having a diameter of 0.5 mm. The mixture was sealed and dispersed with a paint shaker for 5 hours to obtain a black dispersion.

[Preparation of ink A]
A solvent and water were added to the plastic bottle containing the dispersion so as to have the following combination, and the mixture was stirred for about 30 minutes with a paint shaker. The numerical value of the addition amount in the table represents parts by mass. Thereafter, the beads were removed, and filtration and membrane deaeration treatment using a hollow fiber membrane were performed to prepare an ink.

Tripropylene glycol monomethyl ether 240 parts by weight Water 35 parts by weight Pigment dispersion A 100 parts by weight Tripropylene glycol monomethyl ether has an SP value of 20.4, which satisfies the requirements of the present invention.

[Preparation of ink B]
A solvent and water were added to the plastic bottle containing the dispersion so as to have the following combination, and the mixture was stirred for about 30 minutes with a paint shaker. The numerical value of the addition amount in the table represents parts by mass. Thereafter, the beads were removed, and filtration and membrane deaeration treatment using a hollow fiber membrane were performed to prepare an ink.

Tripropylene glycol monomethyl ether 125 parts by weight Water 155 parts by weight Pigment dispersion A 100 parts by weight Tripropylene glycol monomethyl ether has an SP value of 20.4, which satisfies the requirements of the present invention. The configuration is not met.

[Preparation of ink C]
A solvent and water were added to the plastic bottle containing the dispersion so as to have the following combination, and the mixture was stirred for about 30 minutes with a paint shaker. The numerical value of the addition amount in the table represents parts by mass. Thereafter, the beads were removed, and filtration and membrane deaeration treatment using a hollow fiber membrane were performed to prepare an ink.

Dipropylene glycol monomethyl ether 240 parts by weight Water 35 parts by weight Pigment dispersion A 100 parts by weight The propylene glycol monomethyl ether has an SP value of 21.3, which satisfies the requirements of the present invention.

[Preparation of Ink D]
A solvent and water were added to the plastic bottle containing the dispersion so as to have the following combination, and the mixture was stirred for about 30 minutes with a paint shaker. The numerical value of the addition amount in the table represents parts by mass. Thereafter, the beads were removed, and filtration and membrane deaeration treatment using a hollow fiber membrane were performed to prepare an ink.

Ethylene glycol 240 parts by weight Water 35 parts by weight Pigment dispersion A 100 parts by weight The SP value of ethylene glycol is 32.2, which does not satisfy the requirements of the present invention.

[Preparation of ink E]
Water was added to the plastic bottle containing the dispersion and the mixture was stirred for 30 minutes with a paint shaker. The numerical value of the addition amount in the table represents parts by mass. Thereafter, the beads were removed, and filtration and membrane deaeration treatment using a hollow fiber membrane were performed to prepare an ink.

Water 275 parts by mass Pigment dispersion A 100 parts by mass [Preparation of ink F]
A solvent and water were added to the plastic bottle containing the dispersion so as to have the following combination, and the mixture was stirred for about 30 minutes with a paint shaker. The numerical value of the addition amount in the table represents parts by mass. Thereafter, the beads were removed, and filtration and membrane deaeration treatment using a hollow fiber membrane were performed to prepare an ink.

Dipropylene glycol monomethyl ether 145 parts by mass Ethylene glycol 95 parts by mass Water 35 parts by mass Pigment dispersion A 100 parts by mass The above ink satisfies the requirements of the present invention.

[Preparation of ink G]
A solvent and water were added to the plastic bottle containing the dispersion so as to have the following combination, and the mixture was stirred for about 30 minutes with a paint shaker. The numerical value of the addition amount in the table represents parts by mass. Thereafter, the beads were removed, and filtration and membrane deaeration treatment using a hollow fiber membrane were performed to prepare an ink.

Dipropylene glycol monomethyl ether 90 parts by weight Ethylene glycol 150 parts by weight Water 35 parts by weight Pigment dispersion A 100 parts by weight The above ink is a water-soluble organic solvent having an SP value of less than 16.5 to 24.6. Since the ether content is 30% by mass or less of the total ink mass, the requirement of the present invention is not satisfied.

[Evaluation of output stability]
Using the above prepared pigment inks A to E in an environment of 23 ° C. and 20% RH and using a shear mode piezo-type recording head with 256 nozzles, the ink droplet velocity at an ejection interval of 50 milliseconds is set as an initial state. The voltage applied to the recording head was adjusted so that the current was 8 m / sec. Next, the emission interval time was changed, and the relative ratio of the droplet velocity was measured by applying the following equation, and the decap resistance was evaluated according to the following criteria.

  100 ink droplets are ejected at an ejection interval of 50 microseconds, and 100 drops are ejected at an ejection interval of 50 microseconds after an interval time t seconds from the first ejection, and the velocity of the first ink droplet after the interval time t seconds is reached. And this is defined as the droplet velocity after the interval time t.

Relative ratio of droplet velocity (%) = (droplet velocity after ejection interval t seconds) / (droplet velocity at ejection interval 50 milliseconds = 8 m / sec) × 100
A: The interval time t at which the relative ratio of the droplet velocity is 70% or less is 10 seconds or more. O: The interval time t at which the relative ratio of the droplet velocity is 70% or less is 1 second or more and less than 10 seconds. Δ: The interval time t at which the relative ratio of droplet speed is 70% or less is 0.3 second or more and less than 1 second. ×: The interval time t at which the relative ratio of droplet speed is 70% or less is 0.3. Less than a second XX: Ink droplets are not ejected after 3 seconds of intermittent ejection [Image recording]
Using a line head type piezo recording head in which the nozzle diameter is 25 μm, the number of nozzles is 512, and the nozzle resolution is 1440 dpi (dpi means the number of dots per 2.54 cm) arranged in an array. A4 size using inks A to D under the conditions of a recording resolution of 1440 × 1440 dpi (dpi means the number of dots per 2.54 cm), an ink adhesion amount of 10 ml / m ² , and an image size of 280 × 200 mm. A solid image having an ink adhesion amount of 11 ml / m ² and an image size of 200 × 280 mm was printed on one side of NR-80 recycled paper manufactured by Konica Minolta Business Technology.

[Drying method]
For Samples 1 to 7, a drying zone in which a 400 W halogen lamp was installed at a position 2 cm from the paper surface was provided immediately after the line head, and the printed paper was installed so as to be conveyed directly to the drying zone. At this time, the irradiation start time was 2 seconds after printing. The duration of irradiation was 2 seconds.

  For Samples 8 to 14, a drying zone by a dryer that blows hot air at 120 ° C. was provided immediately after the line head, and installed so that the printed paper was conveyed to the drying zone as it was. At this time, a windshield was prepared immediately after the head so that the wind did not hit the head. The time until the printed paper crossed the windshield and hit the wind was 2 seconds after the printing was performed. The time for blowing was 6 seconds.

  For Samples 15 to 16, the positions of the dryer and the windshield were moved and adjusted so that the time from printing to the time when the wind hit was 5 seconds.

  Samples 17 to 19 were not dried.

  Considering only the drying method, it is as follows.

Evaluation of curling and cockling When the infrared irradiation was performed immediately after printing on each sample, the curling and cockling was measured immediately after irradiation. As an evaluation method, the sample was placed on a flat horizontal surface, and the height of the part that floated most from the horizontal surface was set as an evaluation value by a laser displacement meter.

◎: Lift from the horizontal plane is less than 1 mm ○: Lift from the horizontal plane is 1 mm or more and less than 2 mm △: Lift from the horizontal plane is 2 mm or more and less than 3 mm ×: Lift from the horizontal plane is 3 mm or more and less than 5 mm XX: Lift from the horizontal plane is 5 mm or more. Or curled and rounded. Print density Attached to each sample, the surface density 5 minutes after printing was measured.

◎: 1.26 or more ○: 1.23 or more to less than 1.26 Δ: 1.20 or more to less than 1.23 ×: 1.17 or more to less than 1.20 XX: less than 1.17 Measurement of print density The X concentration 938 (Japanese lithographic equipment) was used and the visual concentration in status A was used as the value.

Evaluation of surface drying property Unprinted paper was placed on a sample immediately after preparation, and the paper was rubbed and rubbed from above, and the adhesion of ink from the sample to the stacked paper was examined. At the same time, the surface state was examined by rubbing the surface strongly with a finger.

A: Not attached at all. There is no problem with rubbing with a finger. ○: There is no ink, but some fluff is observed when rubbing with a finger. Δ: Some with ink is seen, and some fluff is seen when rubbing with a finger. Ink adhesion is observed on 1% or more of the paper surface. Or, when it is rubbed with a finger, it peels white. XX: Adhesion of ink is observed in an area of 3% or more of the paper surface. The results of each evaluation are shown in the following table.

  From the results shown in Table 1, it can be seen that the combination of the ink and the drying method satisfying the configuration of the present invention can provide an ink jet recording method with good emission stability, cockling and surface drying properties.

Claims (3)

A water-soluble organic solvent containing at least water, a water-soluble organic solvent, and a pigment, wherein the water content is less than 10 to 50% by mass of the total ink mass, and the water-soluble organic solvent is the most contained among the water-soluble organic solvents. The SP value is 16.5 or more and less than 24.6, and the content of the water-soluble organic solvent having the SP value of 16.5 or more and less than 24.6 is 30% by mass or more and less than 90% by mass of the total ink mass. An ink jet recording method using an ink, wherein the paper is forcibly dried between 0 s and 3 s after landing of the ink. A water-soluble organic solvent containing at least water, a water-soluble organic solvent, and a pigment, wherein the water content is less than 10 to 50% by mass of the total ink mass, and the water-soluble organic solvent is the most contained among the water-soluble organic solvents. The SP value is 16.5 or more and less than 24.6, and the content of the water-soluble organic solvent having the SP value of 16.5 or more and less than 24.6 is 30% by mass or more and less than 90% by mass of the total ink mass. An ink jet recording method using an ink, wherein air is blown on a paper surface between 0 s and 3 s after ink landing. A water-soluble organic solvent containing at least water, a water-soluble organic solvent, and a pigment, wherein the water content is less than 10 to 50% by mass of the total ink mass, and the water-soluble organic solvent is the most contained among the water-soluble organic solvents. The SP value is 16.5 or more and less than 24.6, and the content of the water-soluble organic solvent having the SP value of 16.5 or more and less than 24.6 is 30% by mass or more and less than 90% by mass of the total ink mass. An ink jet recording method using an ink as described above, wherein infrared irradiation is applied to a paper surface between 0 s and 3 s after ink landing.