JP6111747B2 - Inkjet recording method - Google Patents

Description

  The present invention relates to an ink jet recording method. Specifically, the present invention relates to an ink jet recording method for performing image recording by injecting a water-based ink containing a white pigment.

  Recording media and coated papers with a resin surface such as sign use have poor water absorption, and the surface energy of the recording medium is low, so even when printing with aqueous inkjet ink, ink absorption does not occur and ink repels. As a result, the image is disturbed and the fixing property of the ink to the recording medium is low, so that the image durability is poor. For this reason, studies have been made to improve the wettability and fixability to the substrate by adding a large amount of additives such as resins and surfactants to the ink (for example, see Patent Documents 1 to 3).

JP 2000-103995 A JP-A-63-254176 JP 2003-253170 A JP 2012-224004 A JP 2010-69818 A

However, in white ink, the greater the color material component, the greater the concealability, while the color material tends to aggregate during storage. As a result, there have been problems such as injection defects such as injection bending and non-ejection, and deterioration in adhesion to the recording medium.
On the other hand, there has been proposed a droplet ejection apparatus that can obtain excellent ejection stability even in the case of ink having a high drying viscosity by avoiding the generation of heat when the recording head waits for the recording operation (Patent Document 4). ). In addition, a droplet ejection device that efficiently shakes the meniscus with a small number of pulses has been proposed (Patent Document 5). However, none of the droplet ejection devices of Patent Documents 4 and 5 has been able to solve the above-described problem of aggregation specific to white ink.

  In view of the above, an object of the present invention is to provide an ink jet recording method that has good concealability, ejection stability, and adhesion to a recording medium while being white ink.

  The above problems are solved by the following inventions.

1. (B) An ink set including white ink, a plurality of pressure chambers, a pressure generating means for changing the volume in the pressure chamber, and a nozzle communicating with the pressure chamber, and changing the pressure in the pressure chamber to nozzle the liquid in the pressure chamber An ink jet recording apparatus having a recording head to be discharged from the nozzle, and a step of expanding or contracting the volume of the pressure chamber to discharge ink droplets from the nozzle; and (b) a degree of not discharging ink from the nozzle to the pressure generating means The white ink contains a coloring material, a water-soluble resin as a binder, water, a water-soluble organic solvent, a surfactant, and the meniscus of the other color ink. the pulse interval of the minute vibration is represented by the following formula (1), an ink jet recording side pulse interval of the minute vibration of the meniscus of the white ink of the following formula (2) .
Equation (1): Pulse interval of micro vibration = AL × (n + 0.5)
Formula (2): Pulse interval of micro vibration = AL × [n + (− 0.5 to +0.5)]
(In the formulas (1) and (2),
AL is the pulse width of the minute vibration,
n is an integer of 2 or more, and is the same in formulas (1) and (2). )
2. 2. The ink jet recording method according to 1 above, wherein the water-soluble resin is neutralized with ammonia or amines.
3. 2. The ink jet recording method according to 1 above, wherein the acid value of the water-soluble resin is 50 mgKOH / g or more and 130 mgKOH / g or less.
4). 2. The inkjet recording method according to 1 above, wherein the water-soluble organic solvent comprises a water-soluble organic solvent selected from the group consisting of glycol ethers or 1,2-alkanediols having 4 or more carbon atoms.
5. 2. The ink jet recording method according to 1 above, wherein the surfactant is a silicon-based or fluorine-based surfactant.
6). 2. The ink jet recording method according to 1 above, wherein the ink set includes at least one of black ink and chromatic ink as the other color ink.
7). 2. The inkjet recording method according to 1 above, further comprising a step of sending air to a gap between the recording surface of the recording medium and the nozzle surface of the recording head.
8). 2. The ink jet recording method according to 1 above, further comprising a step of cleaning the discharge port of the recording head.

  According to the present invention, there is provided an ink jet recording method having good concealability, ejection stability, and adhesion to a recording medium while being white ink.

It is a figure which shows an example of the pulse interval of the fine vibration of the recording head filled with the white ink. FIG. 6 is a diagram illustrating an example of a pulse interval of micro vibrations of a recording head filled with ink other than white. It is a schematic block diagram of the inkjet recording device which is an example of a droplet discharge device. FIG. 4A is a schematic perspective view of a shear mode liquid ejection head. FIG. 4B is a cross-sectional view of FIG. FIG. 5A to FIG. 5B are diagrams showing an operation at the time of liquid discharge of the shear mode type liquid discharge head. It is a figure which shows an example of a drive signal. FIG. 7A to FIG. 7B are diagrams showing a three-cycle discharge operation. It is a timing chart figure of the drive pulse applied to a pressure chamber. It is a side view which shows schematic structure of the inkjet recording device of another aspect. It is the figure which looked at the inkjet head vicinity with which the inkjet recording device of FIG. 9 is provided from the front. FIG. 4 is a diagram illustrating an example of a discharge pulse interval of a recording head filled with ink.

  Hereinafter, the present invention will be described with reference to embodiments, but the present invention is not limited to the following embodiments. Components having the same function or similar functions in the figures are given the same or similar reference numerals and description thereof is omitted. However, the drawings are schematic. Therefore, specific dimensions and the like should be determined in light of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

  As a result of intensive studies to solve the above-mentioned problems, the present inventor not only improves the adhesion to the recording medium by adding a water-soluble resin to the ink, but also improves the colorant particles between the ink during storage of the ink. As a result, it was found that it becomes difficult to approach, preventing aggregation and increasing the viscosity of the ink to cause precipitation. Furthermore, it has been found that the ink in the vicinity of the nozzle can always be kept in a uniform state by giving a slight vibration to the meniscus in the nozzle of the recording head when ink is not ejected during printing. As a result, the ejection characteristics of the white ink are kept good, so that the color unevenness of the white ink printing portion is reduced and the gloss of the image is also improved, thus completing the present invention.

[Inkjet recording method]
FIG. 1 is a diagram illustrating an example of a pulse interval of fine vibration of a recording head filled with white ink. FIG. 2 is a diagram illustrating an example of a pulse interval of fine vibration of a recording head filled with ink of a color other than white (hereinafter also referred to as “other color ink”). FIG. 11 is a diagram illustrating an example of an ejection pulse interval of a recording head filled with ink.
“AL (Acoustic Length)” in FIG. 1 is ½ of the acoustic resonance period of the pressure chamber. “Pulse width” is defined as the time between 10% from the start of voltage rise and 10% from the start of fall. This AL is applied when a rectangular wave drive pulse is applied to the partition, which is an electrical / mechanical conversion means, and the speed of the ejected liquid is measured, and the rectangular wave voltage value is kept constant and the pulse width of the rectangular wave is changed. Furthermore, it is obtained as a pulse width that maximizes the liquid flight speed. A “rectangular wave” is a waveform in which both the rise time and fall time between 10% and 90% of the voltage are within ½, preferably within ¼ of AL. The “fine pulse interval” is defined as a time between 10% from the start of the fall of the voltage of the first micro-vibration signal and 10% from the start of the rise of the voltage of the second micro-vibration signal. The “ejection pulse interval” is defined as a time between 10% from the start of the fall of the voltage of the first ejection signal and 10% from the start of the rise of the voltage of the second ejection signal.
As described above, the pulse interval of micro vibration can be defined in the same manner as the pulse interval of ejection. Basically, a fine vibration pulse is applied when ejection is not being performed.

The ink jet recording method according to the embodiment will be described step by step with reference to FIG.
(A) First, prepare white ink. The white ink preferably contains a colorant, a water-soluble resin as a binder, water, a water-soluble organic solvent, and a surfactant.
(B) an inkjet having a plurality of pressure chambers, a pressure generating means for changing the volume in the pressure chamber, and a nozzle communicating with the pressure chamber, and having a recording head for changing the pressure in the pressure chamber and discharging the liquid in the pressure chamber from the nozzle. Prepare a recording device. As the ink jet recording apparatus, for example, a device capable of changing the pressure in the pressure chamber by giving a discharge signal and discharging the liquid in the pressure chamber from the nozzle can be used. Specifically, an apparatus as shown in FIG. 3 described later can be used.
(C) A white ink is attached to the ink jet recording apparatus 1 as shown in FIG. A plurality of pressure chambers of one recording head are filled with white ink.

(D) One first pressure chamber to be used for ejection is selected from a plurality of pressure chambers, a first ejection signal is given, and ink is ejected from the nozzles to land on the recording medium. As the first ejection signal, the drive signal generation unit 100 is operated to give a positive voltage expansion pulse with a drive voltage (crest value) Von and a pulse width 1AL as shown by A-cycle in FIG.
(E) One second pressure chamber to be used for ejection is selected from a plurality of pressure chambers, a second ejection signal is given, and ink is ejected from the nozzles to land on the recording medium. As the second ejection signal, the drive signal generation means 100 is operated to give a positive expansion pulse with a drive voltage (peak value) Von and a pulse width 1AL as shown by B-cycle in FIG.

(G) The meniscus in the nozzle is slightly vibrated to such an extent that ink is not ejected from the nozzle to the plurality of pressure chambers that were not selected. For example, as shown in FIG. 1, when ink is not ejected, the pulse interval of the fine vibration of the white ink should be the same as or shorter than the pulse interval of the fine vibration of the other color ink of FIG. Is preferred. This is because the fine ink is applied to the meniscus and the ink in the pressure chamber is stirred to prevent the solvent from evaporating, so that the state of the white ink can be kept uniform. The specific fine vibration pulse interval is defined as the fine vibration pulse width (AL) × (n + 0.5) of the other color ink. The pulse width of micro vibration (AL) × [n + (− 0.5 to +0.5)] is preferable. N in each of the above formulas represents an integer of 2 or more. Although n will not be restrict | limited especially if it is an integer greater than or equal to 2, the integer of 2-7 can be used.
For example, the pulse interval of the fine vibration of the white ink in FIG. 1 is 1.5 (AL) from the following equation.
1 (AL) × [2-0.5] = 1.5
The pulse interval of the minute vibration of the other color ink in FIG. 2 is 2.5 (AL) from the following equation.
1 (AL) × [2 + 0.5] = 2.5
In the case where the ink set is composed of only white ink, it is preferable to adjust the pulse interval of white ink on the assumption that there are other color inks.
“Fine vibration” means shaking the ink meniscus of the ejection head to such an extent that droplets are not ejected. A generally used driving waveform for shaking may be used. Preferably, the amplitude of shaking is not more than the radius of the nozzle diameter. The means for applying the fine vibration is not particularly limited, but a piezo element which is an ink discharge means can be preferably used.

Here, pulse control from the first pressure chamber to the third pressure chamber is shown as an example, but pulse control is performed for the fourth pressure chamber, the fifth pressure chamber, and other pressure chambers in the same manner as described above. .
Although the white ink has been described as an example, pulse control is performed on other color inks, for example, black ink and chromatic color ink, in the same manner as described above under the conditions shown in FIG.

In addition to the above-described steps, (h) a step of sending air to the gap between the recording surface of the recording medium and the nozzle surface of the recording head and (f) a step of cleaning the discharge port of the recording head may be provided. .
(I) The step of cleaning the discharge port of the recording head includes a step (wiping) of cleaning the discharge port with a cleaning roller or cloth in order to keep the nozzle surface clean. Before and after wiping, (nu) ink discharging step may be provided. “Discharging ink” means discharging ink droplets from the inkjet head 2 in a non-image area. It is preferable to discharge ink at regular intervals. For example, it is preferable to discharge 200 to 1000 ink droplets per nozzle for each scan (one reciprocation) of the inkjet head 2.
Regarding the ink and the ink jet recording apparatus used in the ink jet recording method according to the embodiment, those described below are preferably used.

[ink]
Examples of the “ink” used in the embodiment include pigments, water-soluble resins as binders (hereinafter also referred to as “binder resins”), water, water-soluble organic solvents, and surfactants. Examples of the “white ink” include those containing a coloring material, a water-soluble resin as a binder, water, a water-soluble organic solvent, and a surfactant. One of titanium oxide and hollow fine particles can be used as the color material. As the other color ink constituting the ink set, it is preferable to use chromatic ink or black ink. Below, each component is demonstrated.
The binder resin has a function of fixing (adhering) the landed ink droplets to the recording medium. In addition, the binder resin is required not only to improve the abrasion resistance and water resistance of the ink film, but also to have a function of increasing gloss and optical density. Therefore, it is more preferable that the binder resin be easily dispersed in an aqueous solvent, have a certain degree of transparency, and have compatibility with other ink components.

  The binder resin is not particularly limited as long as it can be dissolved or dispersed in an aqueous solvent, and is preferably a water-soluble resin, an aqueous dispersion polymer fine particle, or the like, and is particularly soluble or stable in an aqueous solvent. It is more preferable to use a water-soluble resin because it can improve the fixability of the ink film after curing to a recording medium even when dried at low temperature.

  Examples of water-soluble resins include acrylic resins, styrene-acrylic resins, acrylonitrile-acrylic resins, vinyl acetate-acrylic resins, polyvinyl alcohol resins, polyurethane resins, polyamide resins, polyester resins, polyolefin resins, and the like. . Among these, acrylic resins, polyamide resins, polyvinyl alcohol resins, and polyurethane resins are preferable, and acrylic resins are more preferable.

The acrylic resin may be a homopolymer of (meth) acrylic acid ester or a copolymer of (meth) acrylic acid ester and another copolymerizable monomer. A copolymer of (meth) acrylic acid ester and another copolymerization monomer is particularly preferred because it has a high degree of freedom in designing the resin structure, is easily synthesized by a polymerization reaction, and is low in cost. The content ratio of the structural unit derived from the (meth) acrylic acid ester in the copolymer is preferably 60 to 100% by mass, and preferably 80 to 100% by mass with respect to all monomers constituting the copolymer. Is more preferable.

  Examples of (meth) acrylic acid esters include (meth) acrylic acid alkyl esters. Especially, the C1-C12 alkylester of (meth) acrylic acid is preferable. The (meth) acrylic acid ester may be one type or two or more types. Examples of preferable combinations of two or more kinds of (meth) acrylic acid esters include a combination of methyl methacrylate, acrylic acid C1-C12 alkyl ester, and methacrylic acid C2-C12 alkyl ester.

  Examples of other copolymerization monomers in the copolymer of (meth) acrylic acid ester and other copolymerization monomers include monomers having acidic groups. Examples of the monomer having an acidic group include acrylic acid, methacrylic acid, itaconic acid and the like. Especially, the copolymer of (meth) acrylic acid ester and other copolymerization monomers includes methyl methacrylate, acrylic acid C1-C12 alkyl ester and methacrylic acid C2-C12 alkyl ester as main monomers, and others. A copolymer obtained by polymerizing a monomer having an acidic group as the copolymer monomer is preferable. The total content of the structural units derived from the main monomers (methyl methacrylate, acrylic acid C1-C12 alkyl ester and methacrylic acid C2-C12 alkyl ester) contained in the copolymer is based on the total monomers constituting the copolymer. It is preferable that it is 80-95 mass% with respect to it.

  At least a part of the acidic groups contained in the acrylic resin is preferably neutralized with a base from the viewpoint of increasing the solubility in an aqueous solvent. Examples of the base to be neutralized include alkali metal or alkaline earth metal hydroxides (for example, NaOH, KOH, etc.), amines (for example, alkanolamine, alkylamine, etc.), ammonia and the like. Among these resins, the resin neutralized with amines lowers the solubility of the resin because the amine and ammonia are evaporated together with the aqueous solvent after the ink has landed on the recording medium. A film after drying of the ink containing such a resin is preferable because it has water resistance and is excellent in gloss. Specific examples of amines include triethylamine, 2-dimethylaminoethanol, 2-di-n-butylaminoethanol, methyldiethanolamine, 2-amino-2-methyl-1-propanol, diethanolamine, triethanolamine, and 2-methyl. Examples include aminoethanol.

  The acid value of the water-soluble resin is preferably 50 to 300 mgKOH / g, and more preferably 50 to 130 mgKOH / g. If the acid value of the water-soluble resin is less than 50 mgKOH / g, the resin may not be sufficiently soluble in water and may not be sufficiently soluble in an aqueous solvent. On the other hand, if the acid value of the water-soluble resin is more than 300 mgKOH / g, the ink film becomes soft and the abrasion resistance decreases.

  The acid value of the water-soluble resin refers to the number of milligrams of potassium hydroxide required to neutralize the acid contained in 1 g of the water-soluble resin, and the acid value measurement, hydrolysis acid value measurement (total acid value) of JISK 0070 Measurement).

  The content of the neutralizing base depends on the acid value and content of the water-soluble resin, but the number of chemical equivalents is 0.5 to 5 times the number of chemical equivalents of acidic groups contained in the water-soluble resin. It is preferable to make it. When the content of the neutralizing base is less than 0.5 times the number of chemical equivalents of the acidic groups contained in the water-soluble resin, the effect of increasing the dispersibility of the acrylic resin is sufficiently obtained. It may not be possible. On the other hand, if the content of the neutralizing base is more than 5 times the number of chemical equivalents of the acidic groups contained in the water-soluble resin, the water resistance of the ink film is reduced, discoloration, odor, etc. May occur.

The weight average molecular weight (Mw) of the water-soluble resin is preferably 2.0 × 10 ^{4 to} 8.0 × 10 ⁴ , and more preferably 2.5 × 10 ^{4 to} 7.0 × 10 ^4. . If the weight average molecular weight is less than 2.0 × 10 ⁴ , the fixing ability of the ink is small, and the resulting image may not have sufficient abrasion resistance. On the other hand, when the weight average molecular weight (Mw) is more than 8.0 × 10 ⁴ , the viscosity of the ink is too high, and the ejection stability from the nozzle may be lowered.

  It is preferable that the glass transition temperature (Tg) of binder resin is 30-100 degreeC. If the Tg is less than 30 ° C., the resulting image may not have sufficient abrasion resistance, or blocking may occur. On the other hand, when Tg is higher than 100 ° C., it is considered that the ink film after drying becomes too hard and brittle, and the abrasion resistance may be lowered.

  The content of the binder resin is preferably 1 to 15% by mass and more preferably 3 to 10% by mass with respect to the entire ink. When the content of the binder resin is less than 1% by mass, the function of fixing a color material such as a pigment on the recording medium may not be sufficiently obtained. On the other hand, when the content of the binder resin is more than 15% by mass, the viscosity of the ink becomes high and the injection stability may be lowered.

  The (aqueous) ink according to the embodiment may further include water-based dispersed polymer fine particles in order to further improve the abrasion resistance of the ink film.

  The water-based dispersed polymer fine particles can be composed of the same water-soluble resin as described above. The average particle size of the water-based dispersed polymer fine particles is preferably 300 nm or less, and more preferably 130 nm or less, from the viewpoint that the nozzle of the head is not clogged and an image having good gloss is obtained. Further, the average particle size of the polymer fine particles is preferably 30 nm or more from the viewpoint of production stability.

  The content of the water-dispersible polymer fine particles is preferably 0.7% to 6% by mass with respect to the entire ink, from the viewpoint of easy fixing to a recording medium and long-term storage stability of the ink. More preferably, it is mass%.

  In the present embodiment, an embodiment containing glycol ethers or 1,2-alkanediols as the water-soluble organic solvent is preferable. Glycol ethers and 1,2-alkanediols work stronger as the concentration of glycol ethers etc. increases in the drying process after ink landing due to hydrophobic interactions with pigment dispersions and water-soluble copolymers. Thickening brings about thickening of the ink. Therefore, it is considered that the use of the water-soluble copolymer in combination with glycol ethers or 1,2-alkanediols exerts a remarkable effect of suppressing flipping and bleeding on the recording medium.

  Examples of glycol ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monopropyl ether, dipropylene glycol monomethyl ether, and tripropylene glycol monomethyl ether. . The 1,2-alkanediols include 1,2-alkanediols having 4 or more carbon atoms, such as 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1, Examples include 2-heptanediol.

  Glycol ethers or 1,2-alkanediols are particularly preferably contained in an amount of 1 to 20% by mass with respect to the total mass of the ink from the viewpoint that the effects of the present invention are remarkably exhibited.

A pigment (including hollow fine particles) can be used as the color material of the white ink.
The color material of the other color ink may be a dye, a pigment, or a mixture thereof. Examples of the dye include water-soluble dyes such as acid dyes, direct dyes and basic dyes; disperse dyes containing colored polymers or colored waxes; oil-soluble dyes and the like. Of these, pigments are preferred from the viewpoints of durability and abrasion resistance of the obtained image.

  The pigment may be a known organic pigment or inorganic pigment. Examples of organic pigments include azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments and chelate azo pigments; phthalocyanine pigments, perylene and perylene pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, And polycyclic pigments such as quinophthaloni pigments; dye lakes such as basic dye-type lakes and acid dye-type lakes; nitro pigments; nitroso pigments; aniline black; and daylight fluorescent pigments.

  Specific examples of the pigment are shown below, but the present invention is not limited to these exemplified compounds.

  Preferred examples of organic pigments for magenta or red and violet 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 8, C.I. I. Pigment red 12, C.I. I. Pigment red 15, C.I. I. Pigment red 16, C.I. I. Pigment red 17, C.I. I. Pigment red 22, C.I. I. Pigment red 23, C.I. I. Pigment red 41, 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 112, C.I. I. Pigment red 114, 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 146, C.I. I. Pigment red 148, C.I. I. Pigment red 149, C.I. I. Pigment red 150, C.I. I. Pigment red 166, C.I. I. Pigment red 170, C.I. I. Pigment red 177, C.I. I. Pigment red 178, C.I. I. Pigment red 202, C.I. I. Pigment red 220, C.I. I. Pigment red 222, C.I. I. Pigment red 238, C.I. I. Pigment red 245, C.I. I. Pigment red 258, C.I. I. Pigment red 282, C.I. I. Pigment violet 19, C.I. I. Pigment Violet 23 and the like are included.

  Preferred examples of organic pigments for orange or yellow and brown include C.I. I. Pigment orange 13, C.I. I. Pigment orange 16, C.I. I. Pigment orange 31, C.I. I. Pigment orange 34, C.I. I. Pigment orange 43, C.I. I. Pigment yellow 1, C.I. I. Pigment yellow 3, 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 16, C.I. I. Pigment yellow 17, C.I. I. Pigment yellow 43, C.I. I. Pigment yellow 55, C.I. I. Pigment yellow 74, C.I. I. Pigment yellow 81, C.I. I. Pigment yellow 83, C.I. I. Pigment yellow 93, C.I. I. Pigment yellow 94, C.I. I. Pigment yellow 109, C.I. I. Pigment yellow 110, C.I. I. Pigment yellow 120, C.I. I. Pigment yellow 128, C.I. I. Pigment yellow 129, C.I. I. Pigment yellow 138, C.I. I. Pigment yellow 139, C.I. I. Pigment yellow 147, C.I. I. Pigment yellow 150, C.I. I. Pigment yellow 151, C.I. I. Pigment yellow 153, C.I. I. Pigment yellow 154, C.I. I. Pigment yellow 155, C.I. I. Pigment yellow 175, C.I. I. Pigment yellow 180, C.I. I. Pigment yellow 181, C.I. I. Pigment yellow 185, C.I. I. Pigment yellow 194, C.I. I. Pigment yellow 199, C.I. I. Pigment yellow 213, C.I. I. Pigment Brown 22 and the like are included.

  Preferred examples of organic pigments for green or cyan include C.I. I. Pigment blue 15, C.I. I. Pigment blue 15: 1, C.I. I. Pigment blue 15: 2, C.I. I. Pigment blue 15: 3, C.I. I. Pigment blue 15: 4, C.I. I. Pigment blue 15: 5, C.I. I. Pigment blue 16, C.I. I. Pigment blue 29, C.I. I. Pigment blue 60, C.I. I. Pigment Green 7 etc. are included.

Examples of organic pigments for black include C.I. I. Pigment black 5, C.I. I. Pigment black 7 and the like are included.
Examples of the color material for white include white inorganic pigments, white organic pigments, and white pigments such as white hollow resin particles. Hollow resin particles and titanium dioxide are preferred in terms of whiteness and hiding properties.
Examples of the white inorganic pigment include alkaline earth metal sulfates such as barium sulfate, alkaline earth metal carbonates such as calcium carbonate, silicas such as finely divided silicate and synthetic silicate, calcium silicate, and alumina. , Alumina hydrate, titanium oxide, and metal compounds such as zinc oxide, and talc and clay.
Examples of white organic pigments include C.I. I. Pigment white 6, C.I. I. Pigment white 18, C.I. I. And CI Pigment White 21. Further, organic compound salts disclosed in JP-A-11-129613 and alkylene bismelamine derivatives disclosed in JP-A-11-140365 and 2001-234093 can also be used. Examples of commercially available white organic pigments include ShigenoxOWP, ShigenoxOWPL, ShigenoxFWP, ShigenoxFWG, ShigenoxUL, and ShigenoxU (manufactured by Hakkol Chemical Co., Ltd.).
White hollow resin particles can be obtained, for example, by the method disclosed in US Pat. No. 4,089,800. The hollow resin particles are substantially made of an organic polymer and exhibit thermoplasticity. The types of resins used for the production of the hollow resin particles are preferably cellulose derivatives, acrylic resins, polyolefins, polyamides, polycarbonates, polystyrenes, copolymers of styrene or other vinyl monomers, vinyl acetates, vinyl alcohols, chlorides. Examples thereof include vinyl polymers such as vinyl or vinyl butyral homopolymers or copolymers, and homopolymers and copolymers of diene. Examples of commercially available hollow resin particles include Ropeg OP-62 commercially available from Rohm and Haas and the SX series commercially available from JSR.

  Examples of inorganic pigments include carbon black and titanium oxide.

  The ink used in the embodiment may further contain a pigment dispersant in order to enhance the dispersibility of the pigment. Examples of the pigment dispersant include a hydroxyl group-containing carboxylic acid ester, a salt of a long chain polyaminoamide and a high molecular weight acid ester, a salt of a high molecular weight polycarboxylic acid, and the like.

  The pigment is preferably added to the ink as a pigment dispersion in order to disperse stably. The pigment dispersion may be any dispersion that can be stably dispersed in an aqueous solvent. A pigment dispersion in which a pigment is dispersed with a dispersion resin; a capsule pigment in which the pigment is coated with a water-insoluble resin: a surface-modified, dispersion resin And self-dispersing pigments that can be dispersed without containing.

  The dispersion resin used in the pigment dispersion in which the pigment is dispersed with the dispersion resin is preferably a water-soluble resin. Preferred examples of such water-soluble resins include styrene-acrylic acid-acrylic acid alkyl ester copolymers, styrene-acrylic acid copolymers, styrene-maleic acid copolymers, styrene-maleic acid-acrylic acid alkyl esters. Copolymer, styrene-methacrylic acid copolymer, styrene-methacrylic acid-acrylic acid alkyl ester copolymer, styrene-maleic acid half ester copolymer, vinyl naphthalene-acrylic acid copolymer, vinyl naphthalene-maleic acid copolymer Polymers and the like are included. Further, as a pigment dispersion resin, a water-soluble resin that can be used as a binder resin may be used for dispersion.

  The water-insoluble resin in the capsule pigment in which the pigment is coated with a water-insoluble resin is a resin that is insoluble in water in a weakly acidic to weakly basic range. Specifically, a resin having a solubility in an aqueous solution having a pH of 4 to 10 is 2% or less. Examples of water-insoluble resins include acrylic resins, styrene-acrylic resins, acrylonitrile-acrylic resins, vinyl acetate resins, vinyl acetate-acrylic resins, vinyl acetate-vinyl chloride resins, polyurethane resins, silicon acrylics Resin, acrylic silicon resin, polyester resin, epoxy resin, and the like. The average particle diameter of the capsule pigment is preferably about 80 to 200 nm from the viewpoints of ink storage stability, color developability, and the like.

  The capsule pigment (pigment fine particles coated with a water-insoluble resin) can be produced by a known method. For example, a water-insoluble resin is dissolved in an organic solvent (for example, methyl ethyl ketone), and a base component is further added to partially or completely neutralize acidic groups contained in the water-insoluble resin. A pigment and ion-exchanged water are added to the obtained solution and mixed and dispersed. Thereafter, the organic solvent is removed from the obtained solution, and ion-exchanged water is further added as necessary to prepare a capsule pigment. Alternatively, there is a method in which a monomer is added to a solution in which a pigment and a polymerizable surfactant are dispersed and a polymerization reaction is performed to coat the pigment with a resin.

The weight average molecular weight (Mw) of the aforementioned dispersion resin and water-insoluble resin is preferably 3.0 × 10 ^{3 to} 5.0 × 10 ⁵ , more preferably 7.0 × 10 ^{3 to} 2.0 × 10. ⁵ . The glass transition temperature (Tg) of the dispersion resin and the water-insoluble resin is preferably about −30 to 100 ° C., more preferably about −10 to 80 ° C.

  The mass ratio of the pigment to the dispersion resin is preferably 100/150 to 100/30 for the pigment / dispersion resin. From the viewpoint of enhancing the durability of the image, the ejection stability of the ink, and the storage stability, it is more preferably 100/100 to 100/40.

  The pigment can be dispersed by, for example, a ball mill, sand mill, attritor, roll mill, agitator, Henschel mixer, colloid mill, ultrasonic homogenizer, pearl mill, wet jet mill, paint shaker, or the like.

  From the viewpoint of removing the coarse particles of the pigment dispersion and making the particle size distribution of the pigment fine particles uniform, the pigment dispersion is subjected to a centrifugal separation process or a filtration process using a filter before being added to the ink. Also good.

  The self-dispersing pigment may be a commercial product. Examples of commercially available self-dispersing pigments include CABO-JET200, CABO-JET300 (manufactured by Cabot Corp.), Bonjet CW1 (manufactured by Orient Chemical Industries Ltd.), and the like.

(Surfactant)
The surfactant has a function of facilitating the wetting and spreading of the aqueous ink on the recording medium. The surfactant that can be used in the present invention is not particularly limited, and anionic surfactants such as dialkylsulfosuccinates, alkylnaphthalenesulfonates, and fatty acid salts; polyoxyethylene alkyl ethers, polyoxyethylene alkylallyl Nonionic surfactants such as ethers, acetylene glycols, and polyoxyethylene / polyoxypropylene block copolymers; Cationic surfactants such as alkylamine salts and quaternary ammonium salts; Silicone surfactants; A fluorine-based surfactant or the like can be used.

  Among the above-mentioned surfactants, the ink can easily spread on a non-water-absorbing recording medium (for example, a vinyl chloride sheet) or a low water-absorbing recording medium (for example, printing paper). An activator or a fluorosurfactant is preferred. By including a silicon-based surfactant or a fluorine-based surfactant in the ink of the present invention, the dot diameter of the landed ink droplets can be greatly increased, and a high-quality image with high density and no unevenness can be formed. Can do.

  These surfactants may be used alone or in combination of two or more. Further, these surfactants are preferably used in combination with a water-soluble organic solvent having a low surface tension.

  Preferred examples of the silicon-based surfactant include a polyether-modified polysiloxane compound. Examples of commercially available products include KF-351A and KF-642 manufactured by Shin-Etsu Chemical Co., Ltd., BYK331 and BYK333 manufactured by Big Chemie. , BYK345, BYK347, BYK348, and the like.

  The fluorine-based surfactant may be a compound in which at least a part of hydrogen atoms bonded to the carbon atoms constituting the hydrophobic group is substituted with a fluorine atom in a normal surfactant. Of these, a fluorosurfactant having a perfluoroalkyl group is preferred.

  Examples of commercially available fluorosurfactants include DIC's product name: Megafac F, Asahi Glass Co., Ltd. Product name: Surflon, Minnesota Mining & Manufacturing Company Name: Fluorad FC, manufactured by Imperial Chemical Industry, Inc. Product name: Monflor, manufactured by EI Dupont Nemeras & Company, Inc. Product name: Zonyls, Farbevelke Hoechst : Licobet VPF, Neos Co., Ltd. Trade name: Footagent, Big Chemie Co., Ltd. Trade name: BYK340 (surface conditioner, fluorine-modified polymer) and the like.

  The surfactant content is such that the surface tension of the ink is 15 mN / m or more in order to allow the ink to wet and spread even on coated paper and resin recording media whose surface energy is lower than that of normal paper. It is preferable to adjust so that it may be less than 35 mN / m. Specifically, the content is preferably 0.01% by mass or more and less than 2.0% by mass with respect to the entire ink.

  The aqueous solvent in this embodiment shows the mixture of water and a water-soluble organic solvent.

  The water-soluble organic solvent in the present embodiment is a water-soluble resin or other ink even when the ratio of the water-soluble organic solvent contained in the ink film is relatively large with respect to water, as in the late drying stage of the ink. What can disperse | distribute or melt | dissolve a component uniformly is preferable. Examples of water-soluble organic solvents that can be used in the present invention include (A) a water-soluble organic solvent having a low surface tension, and (B) a recording medium (such as a vinyl chloride sheet) made of a hydrophobic resin. Water-soluble organic solvents that swell are included.

  (A) A water-soluble organic solvent having a low surface tension can easily spread ink even on a non-water-absorbing recording medium (for example, a vinyl chloride sheet) or a low water-absorbing recording medium (for example, a printing paper). Specifically, the water-soluble organic solvent having a low surface tension is preferably a water-soluble organic solvent having a surface tension at 25 ° C. of 45 mN / m or less.

  Such water-soluble organic solvents are preferably glycol ethers or 1,2-alkanediols. Examples of glycol ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monopropyl ether, dipropylene glycol monomethyl ether, and tripropylene glycol Monomethyl ether and the like are included. Examples of 1,2-alkanediols include 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-heptanediol, and the like.

  The content of the water-soluble organic solvent having a low surface tension is preferably 1 to 30% by mass with respect to the entire ink. This is because if it is less than 1% by mass, wetting and spreading on the recording medium is not sufficient, and if it exceeds 30% by mass, the drying property is poor and the image is blurred.

  (B) A water-soluble organic solvent that dissolves, softens, or swells a recording medium (such as a vinyl chloride sheet) made of a hydrophobic resin imparts ink permeability, and allows adhesion of the ink film to the recording medium and abrasion resistance. Can increase sex.

  Examples of such water-soluble organic solvents include cyclic solvents containing nitrogen or sulfur atoms, cyclic ester solvents, lactic acid esters, β-alkoxypropionamides, alkylene glycol diethers, alkylene glycol monoether monoesters and dimethyl sulfones. Xoxides and the like are included.

  Examples of the cyclic solvent containing a nitrogen atom include 2-pyrrolidone, N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, methylcaprolactam, Cyclic amide compounds such as 2-azacyclooctanone are included. Examples of the cyclic solvent containing a sulfur atom include a 5- to 7-membered ring compound, preferably sulfolane.

  Examples of the cyclic ester solvent include γ-butyrolactone, ε-caprolactone, and the like. Examples of the lactic acid ester include butyl lactate, ethyl lactate and the like.

  Examples of β-alkoxypropionamide include compounds represented by the following formula (1).

R _{1 in} formula (1) represents a linear or branched alkyl group having 1 to 6 carbon atoms. The linear or branched alkyl group having 1 to 6 carbon atoms is preferably a methyl group, an ethyl group or an n-butyl group.

R ₂ and R _{3 in} the formula (1) each independently represent a hydrogen atom or a linear or branched alkyl group having 1 to 4 carbon atoms. R ₂ and R ₃ may be the same as or different from each other. The linear or branched alkyl group having 1 to 4 carbon atoms is preferably a methyl group or an ethyl group.

  The β-alkoxypropionamide represented by the formula (1) has permeability to a recording medium, easily dissolves the binder resin, and has high compatibility with an aqueous solvent. Preferred examples of β-alkoxypropionamide include, but are not limited to, 3-butoxy-N, N-dimethylpropionamide (BDMPA), 3-methoxy-N, N-dimethylpropionamide (MDMPA), 3-ethoxy- N, N-diethylpropionamide (EDEPA) and the like are included.

  The β-alkoxypropionamide represented by the formula (1) can be produced, for example, by the method described in JP2009-184079A or WO2008-102615. Moreover, as a commercial item of (beta) -alkoxypropionamide represented by Formula (1), Idemitsu Kosan Co., Ltd. brand name: Ecamide etc. are.

  Examples of the alkylene glycol diether include diethylene glycol diethyl ether. Examples of the alkylene glycol monoether monoester include diethylene glycol monoethyl monoacetate.

  Of these, β-alkoxypropionamide is preferable, and β-alkoxypropionamide represented by the formula (1) is more preferable from the viewpoint of easy wettability and penetration even on a non-water-absorbing recording medium. Since β-alkoxypropionamide can further stably dissolve a water-soluble resin in the ink, good adhesion to a recording medium can be obtained, and a high-quality image having glossiness, abrasion resistance and repellency resistance can be obtained. Easy to obtain. Moreover, the kind of water-soluble organic solvent combined and the freedom degree of usage-amount are also large. Further, since the ink has permeability to the recording medium, the ink is easily dried. Thereby, the ink droplet can be kept at the landing position on the recording medium, and flipping and color bleeding can be suppressed.

  The content of the water-soluble organic solvent that dissolves, softens or swells the recording medium made of a hydrophobic resin is preferably 0.1% by mass or more and less than 40% by mass with respect to the entire ink, and is 1 to 20% by mass. More preferably. When the content is less than 0.1% by mass, the effect of softening or swelling the recording medium may not be sufficiently obtained. When the content is 40% by mass or more, the printer member may be swollen or deteriorated.

  The aqueous solvent that can be used in the present embodiment may further include other water-soluble organic solvents as necessary. Examples of other water-soluble organic solvents include alcohols (eg, methanol, ethanol, propanol, isopropanol, butanol, isobutanol, secondary butanol, tertiary butanol), polyhydric alcohols (eg, ethylene glycol, diethylene glycol, Ethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, butylene glycol, hexanediol, pentanediol, glycerin, hexanetriol, thiodiglycol), amines (eg, ethanolamine, diethanolamine, triethanolamine, N -Methyldiethanolamine, N-ethyldiethanolamine, morpholine, N-ethylmorpholine, ethylenediamine , Diethylenediamine, triethylenetetramine, tetraethylenepentamine, polyethyleneimine, pentamethyldiethylenetriamine, tetramethylpropylenediamine), amides (eg, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, etc.) included.

  The total amount of the aqueous solvent is preferably adjusted so that the viscosity of the ink is in the range of 1 mPa · s or more and less than 50 mPa · s. For example, the total amount of the aqueous solvent is preferably about 1 to 85% by mass with respect to the whole ink. .

  The content of the aqueous organic solvent in the ink used in the embodiment is preferably such that the aqueous organic solvent is contained to such an extent that the binder resin can be dissolved or dispersed even in the ink film after all the water has evaporated. .

  The ink used in the embodiment may further contain other components as necessary. Examples of other components include preservatives, antifungal agents, rust inhibitors, antifoaming agents, viscosity modifiers, penetrants, pH adjusters, drying inhibitors (eg urea, thiourea, ethylene urea, etc.), etc. included.

  The antiseptic and the antifungal agent have a function of maintaining the storage stability of the ink for a long period of time. The preservative and the antifungal agent are not particularly limited, and for example, aromatic halogen compounds (for example, Preventol CMK), methylene dithiocyanate, halogen-containing nitrogen sulfur compounds, 1,2-benzisothiazolin-3-one (for example, PROXEL) GXL).

  In the ink jet recording method according to the embodiment, the ink described above is used, and at the time of ink ejection, the image recording surface of the recording medium is heated to a specific range of temperatures, and the wind speed of the specific range is applied to the image recording surface of the recording medium. In addition, air is blown, and when the ink is not ejected, fine vibration is given to the ink meniscus in the nozzle hole. As a result, it is possible to ensure outstanding ink stability and landing position accuracy over a long period of time, as well as outstanding liquid resistance, glossiness, and anti-bleeding properties of ink related to image quality.

  The above-described ink exhibits the effects of the present invention remarkably when recording on a non-absorbing recording medium such as a vinyl chloride sheet or a low-absorbing recording medium. In addition, it is suitable for printing on plain paper, coated paper, ink jet dedicated paper, and the like.

  Non-absorbent recording media include polymer sheets, boards (soft vinyl chloride, hard vinyl chloride, acrylic plates, polyolefins, etc.), glass, tile, rubber, synthetic paper, and the like.

  Examples of the low absorption or absorption recording medium include plain paper (copy paper, plain paper for printing), coated paper, art paper, inkjet paper, inkjet glossy paper, cardboard, and wood.

  In particular, it is a recording medium having at least polyvinyl chloride on the recording surface side that exhibits the effects of the present invention remarkably. For example, specific examples of the recording medium having polyvinyl chloride include SOL-371G, SOL-373Mm, SOL-4701 (big technos) and glossy vinyl chloride (manufactured by Stemgraph).

[Inkjet recording apparatus]
An ink jet recording apparatus used for carrying out the ink jet recording method according to the embodiment will be described.
FIG. 3 is a schematic configuration diagram of an inkjet recording apparatus 1 which is an example of a droplet ejection apparatus.
The ink jet recording apparatus 1 includes a conveyance roller pair 32, a conveyance roller 31 that is spaced from the conveyance roller pair 32 and faces the conveyance roller pair 32, and a conveyance motor 33 that rotates the conveyance roller 31. A transport mechanism 3 is provided. The recording medium P is disposed so as to pass between the conveyance roller pair 32 and the conveyance roller 31 with one end in the longitudinal direction being sandwiched between the conveyance roller pair 32. The recording medium P is transported in the Y direction by the transport roller 31 by rotating the transport motor 33.

The ink jet recording apparatus 1 includes a guide rail 4 that spans across the width direction of the recording medium P between the transport roller 31 and the transport roller pair 32, and a transporting direction of the recording medium P by a driving unit (not shown). The carriage 5 provided on the guide rail 4 and the recording surface PS of the recording medium P are opposed to each other so as to be able to reciprocate along the illustrated X1-X2 direction (main scanning direction) substantially orthogonal to the (sub-scanning direction). And a recording head 2 mounted on the carriage 5.
The recording head 2 is electrically connected via a flexible cable 6 to a drive signal generation unit 100 (see FIG. 3) provided with a circuit for generating an ejection pulse and a fine vibration pulse described later.

  The recording head 2 scans the recording surface PS of the recording medium P in the X1-X2 direction as the carriage 5 moves in the main scanning direction, and ejects ink droplets from the nozzles during the scanning movement process. Record the desired inkjet image.

  As will be described later, when the recording head 2 is at the image recording standby position, the ink jet recording apparatus 1 slightly vibrates the ink thickened at the nozzle openings. When the recording head 2 has stopped operating for a long time at the image recording standby position, although not shown, the nozzle surface of the recording head 2 is covered with a cap for protection.

  Also, the standby state for the recording operation means that all the nozzles of the recording head are in a state where the ejection of droplets based on the droplet ejection data such as image data is suspended. For example, in the case of the shuttle type recording head 2 that records an image by ejecting liquid droplets in the process of scanning and moving over the width direction of the recording medium P as in the present embodiment, the recording head 2 is placed on the recording medium P. It is not positioned but outside the recording medium P in the width direction and the scanning movement of the recording head 2 is stopped. Specifically, the case where the recording head 2 is stopped at the home position or the maintenance position can be exemplified.

  Although not shown, in the present embodiment, the recording head is stretched over the width direction of the recording medium and ejects droplets toward the recording medium conveyed in a certain direction, thereby performing a recording operation in one pass. The present invention can also be applied to a liquid droplet ejecting apparatus having a line type recording head for performing the above. In the case of such a line type recording head, the waiting time for the recording operation is when the conveyance of the recording medium is stopped. Specifically, it can be exemplified when the recording head or the transport mechanism is in a maintenance state where the operation is stopped.

FIG. 4A is a schematic perspective view of a shear mode type recording head (liquid ejection head) 2. FIG. 4B is a cross-sectional view of FIG. FIG. 5 is a diagram illustrating the operation of the shear mode type recording head 2 during liquid ejection.
As shown in FIG. 4A, the recording head 2 includes a substrate 26 having a plurality of pressure chambers 28 partitioned by a plurality of partition walls 27 and nozzles 23 at portions corresponding to one ends of the pressure chambers 28. And a cover plate 24 disposed on the substrate 26.
As shown in FIG. 4B, one end (hereinafter also referred to as “nozzle end”) of the pressure chamber 28 is connected to a nozzle 23 formed in the nozzle forming member 22 and the other end (hereinafter also referred to as “manifold end”). ) Is connected to a liquid tank (not shown) via an ink supply tube 21 via a flow path 77 and an ink supply port 25. In addition, the pressure chamber 28 extends from the deep groove portion 28a on the outlet side of the pressure chamber 28 (left side of FIG. 4B) and from the deep groove portion 28a to the inlet side of the pressure chamber 28 (right side of FIG. 4B). And a shallow groove portion 28b that gradually becomes shallow. Here, L is the length of the pressure chamber, D is the depth of the pressure chamber, and W is the width of the pressure chamber. Each partition wall 27 is composed of two piezoelectric materials 27a and 27b having different polarization directions. Each electrode 29A, 29B, 29C, which will be described later, and the drive signal generating means 100 are electrically connected via the anisotropic conductive film 78 and the flexible cable 6.

  As shown in FIG. 5A, the shear mode recording head 2 includes a plurality of partition walls 27A, 27B made of a piezoelectric material such as PZT, which is an electromechanical conversion means, between a cover plate 24 and a substrate 26. A plurality of pressure chambers 28A, 28B, 28C... Separated by 27C. FIG. 5A to FIG. 5C show three (28A, 28B, 28C) which are a part of a large number of pressure chambers 28. Electrodes 29A, 29B, and 29C are formed on the surface of the partition wall 27 in each pressure chamber 28 so as to be connected from above the partition walls 27 to the bottom surface of the substrate 26. Each electrode 29A, 29B, 29C is connected to the drive signal generating means 100 via the anisotropic conductive film 78 and the flexible cable 6 of FIG.

  The number of pressure chambers 28 (number of nozzles 23) of the recording head 2 is appropriately set to about 10 to 1000 according to the liquid discharge width of the recording head 2.

  As shown in the present embodiment, when the piezoelectric material is deformed in the shear mode, a rectangular wave described later can be used more effectively, lowering the driving voltage and more efficient driving. Is possible.

  The drive signal generation means 100 includes a drive signal generation circuit that generates a series of drive signals including a plurality of drive pulses for each pixel period, and a drive signal supplied from the drive signal generation circuit for each pressure chamber. A drive pulse selection circuit that selects a drive pulse in accordance with pixel data and pressure chamber selection pattern data and supplies the selected pulse to each pressure chamber. The drive signal generation means 100 supplies a drive pulse for driving the partition wall 27 as an electro-mechanical conversion means according to the data of each pixel and the pressure chamber selection pattern data. In the present embodiment, the drive pulse is returned to the original volume after contracting the expansion pulse composed of a rectangular wave that returns the original volume after expanding the volume of the pressure chamber and the volume of the pressure chamber as the ejection pulse. A contraction pulse consisting of a rectangular wave.

  Each partition wall 27 is composed of two piezoelectric materials 27a and 27b having different polarization directions as shown by arrows in FIGS. 5A to 5C. The piezoelectric material is, for example, a portion denoted by reference numeral 27a. It is sufficient that it is at least part of the partition wall 27.

  FIG. 6 shows an example of the drive signal. In this example, a description will be given by taking an example in which the driving signal is composed of one type of driving pulse for each of an expansion pulse and a contraction pulse.

The electrodes 29 </ b> A, 29 </ b> B, and 29 </ b> C in FIG. 5A are controlled using the drive signal generation unit 100.
Then, as shown in FIG. 6, a positive voltage expansion pulse with a drive voltage (crest value) Von and pulse width 1AL, and a negative voltage contraction with a drive voltage (crest value) Voff and pulse width 2AL applied after the expansion pulse. An ejection pulse consisting of a pulse is applied.
Then, the liquid is ejected from the nozzle 23 by the operation exemplified below. Here, both the expansion pulse and the contraction pulse are rectangular waves.

  As shown in FIG. 5A, when the drive pulse is not applied to any of the electrodes 29A, 29B, and 29C, none of the partition walls 27A, 27B, and 27C is deformed. However, when the electrodes 29A and 29C are grounded and an expansion pulse is applied to the electrode 29B, an electric field perpendicular to the polarization direction of the piezoelectric material constituting the partition walls 27B and 27C is generated, and each of the partition walls 27B and 27C has a partition wall 27A. , 27B occurs in the joint surface. Then, as shown in FIG. 5B, the partition walls 27B and 27C are deformed outward from each other, the volume of the pressure chamber 28B is expanded, a negative pressure is generated in the pressure chamber 28B, and the liquid flows.

Thereafter, when the potential is returned to 0, the partition walls 27B and 27C return from the expanded position in FIG. 5B to the neutral position in FIG. 5A, and high pressure is applied to the liquid in the pressure chamber 28B. Further, as shown in FIG. 5C, when the contraction pulse is applied so as to deform the partition walls 27B and 27C in the opposite directions to contract the volume of the pressure chamber 28B, positive pressure is generated in the pressure chamber 28B. Arise.
As a result, the meniscus in the nozzle due to a part of the liquid filling the pressure chamber 28B changes in the direction pushed out from the nozzle. When the positive pressure becomes so large that the liquid is discharged from the nozzle, the liquid is discharged from the nozzle. Thereafter, when the potential is returned to 0 and the partition walls 27B and 27C are returned from the contracted position to the neutral position, a part of the remaining pressure wave is canceled. The other pressure chambers operate in the same manner as described above by applying the ejection pulse.

  In the example shown in FIG. 6, it is preferable that the drive voltage Von of the expansion pulse and the drive voltage Voff of the contraction pulse satisfy | Von |> | Voff |. When the relationship of | Von |> | Voff | is satisfied, there is an effect of promoting the return of the meniscus in the nozzle after ejection to the steady position, particularly when the viscosity of the liquid to be ejected is high, and high-speed stable emission is possible, which is preferable. It is an aspect.

  Note that the reference voltage of the voltage Von and the voltage Voff is not always zero. The voltage Von and the voltage Voff are respectively differential voltages from the reference voltage.

  When the recording head 2 having the plurality of pressure chambers 28 separated by the partition walls 27 at least partially made of the piezoelectric material is driven as described above, when the partition wall of one pressure chamber performs the ejection operation, the adjacent pressure is detected. The room is affected. Therefore, normally, among the plurality of pressure chambers 28, the pressure chambers 28 that are separated from each other by sandwiching two or more pressure chambers 28 are grouped into one set so as to be divided into three or more sets, The drive control is performed so that the liquid discharge operation is sequentially performed in time division for each set. For example, when all the pressure chambers 28 are driven to output a solid image, a so-called three-cycle discharge method is performed in which every two pressure chambers 28 are selected and discharged in three phases.

With respect to the three-cycle discharge operation, a comparative example without thinning out of the discharge nozzle will be further described with reference to FIG. In the example shown in FIG. 7, the liquid ejection head has a pressure chamber composed of 12 pressure chambers 28 of A1, B1, C1, A2, B2, C2, A3, B3, C3, A4, B4, and C4. explain.
In addition, FIG. 8 shows a timing chart of drive pulses applied to the pressure chambers 28 in each set of A, B, and C at this time. In FIG. 8, the vertical axis represents pressure chambers A1 to C4, and the horizontal axis represents time. D in FIG. 8 is a pulse signal of the encoder, and FIG. 8 shows a timing chart of two-cycle three-cycle driving. Thereafter, three-cycle driving is similarly repeated.

  At the time of liquid discharge, first, in the first period t1, the electrodes of the pressure chambers of the B group and the C group are grounded, and then the discharge pulse Pa is applied to the electrodes of the pressure chambers of the A group (A1, A2, A3, A4). Apply. When a discharge pulse Pa composed of an expansion pulse and a contraction pulse is applied to the A set of pressure chambers, the liquid is discharged from the A set of pressure chambers.

FIG. 9 is a side view showing a schematic configuration of an ink jet recording apparatus 1A according to another aspect. FIG. 10 is a view of the vicinity of the inkjet head provided in the inkjet recording apparatus 1A of FIG. 9 as viewed from the front. The ink jet recording apparatus is not limited to the above-described ink jet recording apparatus 1, and for example, an ink jet recording apparatus 1A as shown in FIG. 9 may be used.
The ink jet recording apparatus 1A includes a platen 52 in which a heater 30 is incorporated as a heating means and a guide rail (not shown) and a direction orthogonal to the transport direction of the recording medium P (X direction in FIG. 9) ( The carriage 5 configured to be capable of reciprocating in the Y direction in FIG. 10, the inkjet head 2 mounted on the carriage 5 with the nozzle forming member 22 facing the image recording surface of the recording medium P, and the carriage 5, a cover 10 that covers the carriage 5 from the side to the top, and air blowing means 55 a to 55 f that blow air on the image recording surface of the recording medium P.

The cover 10 includes a front cover 11 disposed on the downstream side in the conveyance direction of the recording medium P, a back cover 12 disposed on the upstream side in the conveyance direction of the recording medium P, and a top plate 13.
The platen 52 conveys the recording medium P placed on the upper surface in a predetermined direction (X direction in FIG. 9). The heater 21 has a temperature control function, and by heating the recording medium P from the back side of the image recording surface of the recording medium P, the image recording surface of the recording medium P can be held in a predetermined temperature range. It is said that.

  The air blowing means 55a is composed of a fan provided on the front cover 11, and is configured to blow air on the image recording surface of the recording medium P by an air flow when air is sucked or exhausted from the outside to the inside of the cover 10. Has been.

  The air blowing means 55b is composed of a fan provided on the back cover 12, and is configured to blow air on the image recording surface of the recording medium P by an air flow when air is exhausted or sucked from the outside to the inside of the cover 10. Has been.

  The air blowing means 55c and 55d shown in FIG. 10 are each composed of a fan provided on the carriage 5, and are configured to blow air on the image recording surface of the recording medium P by an air flow when air is sucked or exhausted. Yes.

  The air blowing means 55e and 55f are each composed of a blower provided on the carriage 5, and are configured to blow air on the image recording surface of the recording medium P by an air flow when air is sucked or exhausted. The air blowing means 55e and 55f are provided on the forward path side and the return path side of the carriage 5, respectively.

  The blowing units 55a to 55f are configured such that the blowing direction can be changed independently. In the illustrated example, the blowing direction of the blowing units 55a to 55d is substantially parallel to the image recording surface of the recording medium P. The blowing direction of the blowing means 55e and 55f is oriented in a direction substantially perpendicular to the image recording surface of the recording medium P.

  The ink jet recording apparatus 1A ejects ink from the nozzles of the ink jet head 2 that reciprocates in the Y direction in FIG. 10 onto the image recording surface of the recording medium P conveyed in the X direction in FIG. Record an image on

  In the present embodiment, the blowing direction of the blowing units 55a to 55f is not particularly limited, but the blowing direction of the blowing units 55a to 55d is parallel to or parallel to the image recording surface of the recording medium P. The inclination direction is preferably within 30 °. On the other hand, the blowing direction of the blowing means 55e and 55f is preferably a vertical direction with respect to the image recording surface of the recording medium P, or an inclined direction within 30 ° with respect to the vertical direction.

  In the above description, the case where the front cover 11 and the back cover 12 are each provided with the air blowing means 55a and 55b has been described. However, the present invention is not limited to this, and two or more of the front cover 11 and the back cover 12 are provided. You may provide the ventilation means.

  The aspect of the air blowing means provided in the ink jet recording apparatus 1A is not limited to the above-described one, and as long as it has at least one or more air blowers on the image recording surface of the recording medium such as a fan or a blower. Good.

  Specifically, it is preferable that the air blowing during the ejection of the ink is performed so as to satisfy the following condition (A) or (B) using the ink jet recording apparatus 1A of FIGS. In the following description, the wind speed at the air blowing port and the wind speed in the gap C between the nozzle forming member 22 and the image recording surface of the recording medium P can be measured with a general anemometer.

Condition (A): The ratio of the air speed at the air outlet of at least one of the air blowing means 55a to 55f to the moving speed of the carriage 5 (air blowing air speed / carriage moving speed) is in the range of 5 to 10. There is.
Condition (B): The ratio of the wind speed in the gap C between the nozzle forming member 22 and the image recording surface of the recording medium P to the moving speed of the carriage 5 (gap wind speed / carriage moving speed) is in the range of 1 to 2. about.

  The condition (A) only needs to be satisfied in at least one of the air blowing means 55a to 55f for blowing air on the image recording surface of the recording medium P, and preferably the front cover 11 It is preferable that the air supply means 55a and / or the air supply means 55b provided on the back cover 12 are filled. The wind direction of the wind that brings about such “wind velocity at the air outlet” is not particularly limited. That is, the air outlet of the air blowing means may be either when sucking air or discharging air.

  In the above condition (B), the “gap air velocity” can reflect the influence of air blowing by all the air blowing means 55a to 55f that blow air on the image recording surface of the recording medium P. The influence of the air blowing by the air blowing means 55e and 55f is strongly reflected. The wind direction of the wind that causes such a gap wind speed is not particularly limited.

  In the above conditions (A) and (B), the “moving speed of the carriage 5” is the moving speed of the carriage 5 that reciprocates in the forward path or the return path, and is not particularly limited. The range is preferably 3 (m / s).

  It is preferable to blow air on the image recording surface of the recording medium at a specific range of wind speed and to heat the image recording surface of the recording medium P to a temperature in the specific range.

  Specifically, the heating at the time of ink ejection is performed at a temperature of 30 ° C. or more and 70 ° C. or less at the time of landing at least the ejected ink by heating from the back side of the image recording surface of the recording medium P. It is preferable to carry out so as to keep in this range. For example, the temperature of the image recording surface can be maintained by the heater 21 having the temperature control function of FIG.

(Other embodiments)
As mentioned above, although this invention was described by embodiment, it should not be understood that the description and drawing which form a part of this indication limit this invention. From this disclosure, various alternative embodiments, examples and operational techniques will be apparent to those skilled in the art.
For example, in the ink jet recording method according to the embodiment, in the step of fine vibration, the timings of the fine vibrations in the first pressure chamber, the second pressure chamber, and the third pressure chamber are the same. However, as shown in FIG. 11, the timings of the minute vibrations of the first pressure chamber, the second pressure chamber, and the third pressure chamber may be different. However, it is preferable that the pulse intervals of the fine vibrations of the first pressure chamber, the second pressure chamber, and the third pressure chamber are the same.
In the ink jet recording method according to the embodiment, the white ink has been mainly described. However, as a modified example of the embodiment, (a) an ink jet recording method in which the step of preparing an ink set containing white ink is replaced with the step of (a) preparing an ink set containing white ink and black ink. Is provided. This is because even when black ink is used, ejection stability and good adhesion to a recording medium can be obtained as in the ink jet recording method according to the above-described embodiment. This is because, when printing on a recording medium other than white, such as a transparent recording medium, the black ink is printed after the white ink is printed, so that the visibility and the color developability are enhanced. For the same reason, there is also provided an ink jet recording method in which the above-mentioned step (A) is replaced with a step (A-3) of preparing an ink set including white ink and chromatic color ink.
However, from the viewpoint of obtaining concealability in a recording medium other than white, it is preferable to use the ink jet recording method using an ink set containing white ink.
As described above, the present invention naturally includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

Example 1
Examples of the present invention will be described below, but the present invention is not limited to such examples.
(Preparation of samples 1 to 10)
(Preparation of black pigment dispersion)
As a pigment dispersant, 20 parts by mass of efka4585 (solid content: 50% by mass, manufactured by BASF) was added to 65 parts by mass of ion-exchanged water. To this solution, 15 parts by mass of carbon black pigment was added and premixed, and then dispersed with a sand grinder filled with 50% by volume of 0.5 mm zirconia beads. Thereby, a black pigment dispersion having a pigment solid content of 15% by mass was obtained.

(Preparation of water-soluble resin)
Synthesis Example of Water-Soluble Resin A 186 parts of 2-propanol was placed in a flask equipped with a dropping funnel, a reflux tube, a nitrogen introduction tube, a thermometer, and a stirrer and heated to reflux while bubbling nitrogen. 50 parts by mass of methyl methacrylate, 25 parts by mass of 2-ethylhexyl acrylate, and 25 parts by mass of methacrylic acid were added to the obtained 2-propanol to prepare a mixed solution. A monomer solution in which 0.5 part by mass of an initiator (AIBN) was dissolved was dropped into the obtained mixed solution with a dropping funnel over 2 hours. After the dropwise addition, the mixture was further heated and refluxed for 5 hours, then allowed to cool, and 2-propanol was distilled off under reduced pressure. Thereby, a copolymer (acrylic copolymer resin) of (meth) acrylic acid ester and another copolymerizable monomer was obtained.
To 20 parts by mass of the obtained acrylic copolymer resin, 67.8 parts by mass of ion-exchanged water and an aqueous sodium hydroxide solution as a neutralizing base were added and stirred at 70 ° C. to dissolve the resin. Thereby, an aqueous solution of a water-soluble acrylic resin having a resin solid content of 20% by mass was obtained. The amount of sodium hydroxide aqueous solution added was 1.05 times the number of chemical equivalents of the acidic equivalents of the acrylic copolymer resin.
The weight average molecular weight (Mw) of the water-soluble resin was measured by GPC. The measurement conditions are shown below.
Column: Tosoh TSKgel G40000 + 2500 + 2000HXL, 40 ° C.
Eluent: THF 1.0 (ml / min)
Injection volume: 100 μl
Detection: RI
Calibration curve: standard polystyrene.
The acid value (mgKOH / g) was measured by the method defined in JIS K0070.
As a result, the weight average molecular weight (Mw) of the resin A was 37000, and the acid value was 164.
Resins C to E were obtained in the same manner to obtain an aqueous solution of a water-soluble resin using the monomer composition and neutralizing base shown in Table 1. Only JONDRYL 62J (solid content concentration 34 mass%, manufactured by BASF) was used as the resin B only.
In addition, the abbreviation of the monomer in Table 1 shows the following contents.
MMA: methyl methacrylate BA: n-butyl acrylate EHA: 2-ethylhexyl acrylate BMA: n-butyl methacrylate MAA: methacrylic acid AA: acrylic acid St: styrene

(Preparation of white ink 1)
30 parts by mass of an aqueous solution of the water-soluble acrylic resin, 5.2 parts of ion-exchanged water, 5 parts by mass of 1,2-hexanediol, 10 parts by mass of dipropylene glycol monomethyl ether, and Megafac F-444 ( 0.1 parts by mass of DIC Corporation) and 1 part by mass of Olfine E1010 (Nisshin Chemical Industry Co., Ltd.) were added and stirred. Next, 48.7 parts by mass of commercially available hollow resin particles SX8782 (D) (solid content concentration 20.5% by mass, manufactured by JSR Corporation) was added and stirred as a coloring material. The resulting solution was filtered with a 3 μm filter to obtain white ink 1. The water-soluble resin is contained in an amount of 6% by mass with respect to the mass of the entire ink, and the pigment is contained in an amount of 10% by mass with respect to the mass of the entire ink.

(Preparation of black ink 1)
The black ink is the same as the white ink except that the black pigment dispersion is replaced with 20 parts by weight of the color material of the white ink 1 and the rest is adjusted to 100 parts by weight by adjusting the amount of ion-exchanged water. Was prepared.
An ink set composed of the white ink 1 and the black ink 1 was used as a sample 1.

Ink sets consisting of white ink and black ink were prepared as Samples 2 to 10 in the same manner as Sample 1, except that the components shown in Table 2 were replaced.
As resin B in Tables 1 and 2, “JONDRYL 62J (solid content 34% by mass, manufactured by BASF)” was used.

(Evaluation of samples 1 to 10)
The obtained samples 1 to 10 were subjected to discharge experiments according to the following image forming method under the conditions shown in Table 2 with the pulse intervals of the fine vibrations of the white ink and the black ink. And based on the below-mentioned reference | standard, it evaluated about each item of injection stability, water resistance, and adhesiveness. The obtained results are summarized in Table 2.

＜画像形成方法＞
インクジェットヘッド２として、ＫＭ５１２ＭＮ（コニカミノルタＩＪ社製）駆動周波数１３ｋＨｚ、最小液滴量１４ｐｌのものを用いた。そして、キャリッジに吐出ヘッドを４列搭載したオンデマンド型のインクジェットプリンターのインクジェットヘッドの１つに、得られた白色インク、もう１つに黒色インクを装填した。インクジェットヘッドの電極に、インク液滴の飛翔速度が６ｍ／ｓｅｃとなるように調整した電圧を印加して駆動させた。また、メニスカスの微振動のパルス幅は１ＡＬとし、微振動のパルス間隔は表２に示す通りに設定して後述の画像を印画した。

<Image forming method>
As the inkjet head 2, a KM512MN (manufactured by Konica Minolta IJ) drive frequency of 13 kHz and a minimum droplet volume of 14 pl was used. Then, the obtained white ink was loaded into one of the inkjet heads of an on-demand type inkjet printer in which four rows of ejection heads were mounted on the carriage, and the black ink was loaded into the other. A voltage adjusted so that the flying speed of the ink droplet was 6 m / sec was applied to the electrode of the inkjet head to drive it. Further, the pulse width of the fine vibration of the meniscus was set to 1 AL, and the pulse interval of the fine vibration was set as shown in Table 2 to print an image described later.

On a soft vinyl chloride sheet IJ180-10 (manufactured by Sumitomo 3M Limited) for a solvent inkjet printer as the recording medium P, a white and black solid image with a resolution of 720 dpi × 720 dpi, 10 cm × 10 cm, 100% printing rate and 50%. To form a recorded image.
Note that air was constantly blown during image formation using a blower fan such as 55d and e in FIG. 10 in the gap between the recording surface of the recording medium P and the nozzle surface of the inkjet head.

A. Evaluation of ejection stability The ejection stability of the ink during image recording was evaluated based on the following criteria.
A: Image defect (streaks failure) is not recognized at all, and the image is uniform. O: Slight fading is observed at the image writing portion (a range of 2 mm or less from the writing portion). Δ: Ink ejection Occurrence of image defects (streaks) caused by defects is slightly observed. X: Generation of image defects (streaks) caused by defective ejection of ink is recognized. It was judged.

B. Evaluation of water resistance Each of the solid images prepared above was rubbed 10 times with cotton (Kanakin No. 3), and the degree of image density reduction was visually observed, and water resistance was evaluated according to the following criteria.
◎: No color fading is observed at all. ○: Some color fading is observed, but the image is not a concern. △: Color fading is slightly confirmed, and a slight deterioration in image quality is also observed. Large and has a large impact on image quality

C. Evaluation of image fixability (adhesiveness) According to a cross-cut test of JIS K 5400, adhesive tape (Scotch # 250, manufactured by Sumitomo 3M) was pasted on each of the solid images produced above, and one reciprocating press with a 2 kg roller was performed at once. The number of strip-like samples that were peeled and remained was examined, and the adhesion was evaluated.
A: Adhesive residual rate 100%
○: Adhesion residual rate of 80% or more and less than 100% Δ: Adhesion residual rate of 50% or more and less than 80% ×: Adhesion residual rate of less than 50%

From the results of Samples 1 to 8 and Samples 9 and 10, it was found that the ejection stability was improved by applying vibration to the ink set at a predetermined fine vibration pulse interval.
From the results of Samples 1 and 2 and Samples 3 to 8, it was found that the water resistance is improved by neutralizing the water-soluble resin with ammonia or amines.
From the results of Samples 1 to 4 and Samples 5 to 8, it was found that the water resistance is improved when the water-soluble resin has a predetermined oxidation.

(Example 2)
(Preparation of samples 11-19)
Sample 11 was prepared by the following procedure.
The white pigment of the white ink was changed to “NanoTek® Slurry (solid content concentration: 15% by mass, manufactured by C-I Kasei Co., Ltd.)” which is a commercially available titanium dioxide. The white ink 11 and the black ink 11 were obtained in the same manner as in Example 1, replacing the components shown in FIG.
Samples 12 to 19 were prepared in the same manner as Sample 11, except that the components shown in Table 3 were replaced.

(Evaluation of Samples 11 to 19)
For the obtained samples 11 to 19, on a soft vinyl chloride sheet IJ180-10 (manufactured by Sumitomo 3M Limited) under the same discharge conditions as in Example 1, a printing rate of 100% with a resolution of 720 dpi × 720 dpi, 10 cm × 10 cm and 50% white and black solid images were created. The presence or absence of slight vibrations of the meniscus during printing is as shown in Table 3, and ejection was performed under the conditions of all pulse intervals of 6.5 AL and pulse width of 1 AL. Based on the criteria described later, each of the image quality and gloss items was evaluated. The results obtained are summarized in Table 3.
In addition, the abbreviation in Table 3 shows the following contents.
2) Water-soluble solvent:
1,3-BDO: 1,3-butanediol 1,2-HDO: 1,2-hexanediol DPGPE: Dipropylene glycol monopropyl ether DPG: Dipropylene glycol DPGME: Dipropylene glycol monomethyl ether B100: Ecamide B100 (β -Alkoxypropionamides (made by Idemitsu Kosan Co., Ltd.)

3) Surfactant Olfine E1010: Acetylene glycol surfactant (manufactured by Nissin Chemical Industry Co., Ltd.)
F-444: Fluorosurfactant (Megafac F-444, manufactured by DIC Corporation)
KF-351: Silicone surfactant (manufactured by Shin-Etsu Chemical Co., Ltd.)

A. Image quality evaluation (Liquid tolerance (white stripes))
An image portion having a print rate of 50% of the recorded image was observed with a microscope, and the shape of adjacent dots was observed. The evaluation of the liquid-side resistance was performed based on the following criteria.
○: Adjacent dots are in contact with each other by completely forming a perfect circle. Δ: The portions where the dots are in contact are slightly inflated, but each of them is circular. ×: The dots are merged to form an ellipse. It looks like

B. Evaluation of Glossiness For each of the prepared solid images, the glossiness of the printed part was visually observed and evaluated according to the following criteria.
A: There is no gloss difference between the printed part and the non-printed part, and the glossiness is excellent. ○: There is a slight difference in gloss between the printed part and the non-printed part, but there is no problem in image quality. Gloss difference from the printed part can be recognized, and the image quality is unacceptable. ×: The difference in gloss between the printed part and the unprinted part is large, and the image quality is significantly deteriorated.

From the results of Sample 11 and Sample 12, it was found that image quality and glossiness are improved by applying vibration to the ink set at a predetermined fine vibration pulse interval.
Moreover, it turned out that the image quality and glossiness improve by using the predetermined water-soluble solvent and surfactant from the result of samples 11-19.

DESCRIPTION OF SYMBOLS 1 Inkjet recording apparatus 2 Recording head 21 Ink tube 22 Nozzle formation member 23 Nozzle 24 Cover plate 25 Ink supply port 26 Substrate 27, 27A, 27B, 27C Partition 27a, 27b Piezoelectric material 28, 28A, 28B, 28C Pressure chamber 29A, 29B , 29C Electrode 3 Conveying mechanism 31 Conveying roller 32 Conveying roller pair 33 Conveying motor 4 Guide rail 5 Carriage 6 Flexi cable 100 Drive signal generator P Recording medium PS Recording surface 1A Inkjet recording device 10 Cover 11 Front cover 12 Back cover 13 Top plate 52 Platen 30 Heater 55a-55f Air blowing means

Claims (9)

An ink set including white ink, a plurality of pressure chambers, pressure generating means for changing the volume of the pressure chamber, and a nozzle communicating with the pressure chamber, and changing the pressure in the pressure chamber to change the liquid in the pressure chamber Preparing an inkjet recording apparatus having a recording head to be ejected from a nozzle, expanding or contracting the volume of the pressure chamber, and ejecting ink droplets from the nozzle;
Finely vibrating the meniscus in the nozzle to such an extent that ink is not ejected from the nozzle to the pressure generating means,
The white ink contains a color material, a water-soluble resin as a binder, water, a water-soluble organic solvent, and a surfactant, and the pulse interval of the slight vibration of the meniscus of the other color ink is expressed by the following formula (1). An ink jet recording method, wherein the pulse interval of the fine vibration of the meniscus of the white ink is expressed by the following formula (2).
Equation (1): Pulse interval of micro vibration = AL × (n + 0.5)
Formula (2): Pulse interval of micro vibration = AL × [n + (− 0.5 to +0.5)]
(In the formulas (1) and (2),
AL is the pulse width of the minute vibration,
n is an integer of 2 or more, and is the same in formulas (1) and (2). )   The inkjet recording method according to claim 1, wherein the water-soluble resin is neutralized with ammonia or amines.   2. The ink jet recording method according to claim 1, wherein an acid value of the water-soluble resin is 50 mgKOH / g or more and 130 mgKOH / g or less.   2. The ink jet recording method according to claim 1, wherein the water-soluble organic solvent contains a water-soluble organic solvent selected from the group consisting of glycol ethers or 1,2-alkanediols having 4 or more carbon atoms. .   The inkjet recording method according to claim 1, wherein the surfactant is a silicon-based or fluorine-based surfactant.   The ink jet recording method according to claim 1, wherein the ink set includes at least one of black ink and chromatic ink as the other color ink.   2. The ink jet recording method according to claim 1, further comprising a step of sending air to a gap between a recording surface of the recording medium and a nozzle surface of the recording head.   The inkjet recording method according to claim 1, further comprising a step of cleaning an ejection port of the recording head. 2. The ink jet recording method according to claim 1, wherein a pulse interval of the fine vibration of the meniscus of the white ink is shorter than a pulse interval of the fine vibration of the meniscus of the other color ink.

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