JP2016030776A - Ink set for inkjet, and inkjet recording method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ink set for inkjet capable of obtaining an image with no blurring and high glossiness when an aqueous ink of a color different from a white ink is printed on the white ink.SOLUTION: In an ink set for inkjet containing a white ink, and inks of at least two or more colors of inks composed of inks of colors different from the white ink, all of the inks of the two or more colors of the inks contain at least water, a water-soluble organic solvent, a pigment and resin particles. The water-soluble organic solvent contained in the white ink contains glycol ether having a boiling point of 200°C or higher and 250°C or lower. A content of the resin particles contained in the white ink is the smallest in all of the inks.SELECTED DRAWING: None

Description

  The present invention relates to an ink jet ink set and an ink jet recording method using the same.

Ink jet printers are widely used in general households as digital signal output devices because they have advantages such as low noise, low running cost, and easy color printing.
In recent years, inkjet technology has been used not only for home use but also for industrial purposes such as displays, posters, and bulletin boards.
As inks for ink-jet recording in industrial applications, so far, solvent-based ink-jet inks containing a resin in which an organic solvent is used as a vehicle and dissolved in an organic solvent, and UV-curable ink-jet inks mainly composed of a polymerizable monomer have been widely used. Has been used.
However, solvent-based ink-jet inks are not preferred from the viewpoint of environmental impact because they evaporate a large amount of solvent in the atmosphere, and UV curable ink-jet inks may have skin sensitivity depending on the monomers used. Since the expensive ultraviolet irradiation device needs to be incorporated in the printer main body, the field of application is limited.

Against this background, recently, inkjet technology development has been carried out in which water-based ink, which has been used as a household inkjet ink so far, has a low environmental burden and is used for industrial purposes. (For example, see Patent Documents 1 and 2)
However, since the water-based ink dries moisture in the ink, the water-based ink has a problem in that the quick-drying is inferior to the solvent-based ink and the image is likely to be blurred. In particular, when printing needs to be performed at high speed, it is necessary to eject a large amount of ink at a time. (For example, see Patent Document 3)
Even with water-based ink that can prevent uniform image formation and bleeding on the substrate by the above method, white ink is formed on the transparent substrate, and then ink of a color other than white ink is applied on the white ink. In other words, in the case of multilayer coating, color inks other than the white ink applied on the white ink have a problem that bleeding tends to occur when the drying property of the white ink is insufficient.

  The present invention aims to solve the above-described problems of the prior art, and when a water-based ink having a color different from that of the white ink is printed on the white ink, an image having no gloss and high gloss can be obtained. An object is to provide an ink set for inkjet.

  As a result of examining the composition in the water-based ink and the composition of the ink set, the present inventors have found that all inks including white ink and at least two colors of inks different from white ink are at least The white ink contains water, a water-soluble organic solvent, a pigment, and resin particles. The white ink contains glycol ether having a boiling point of 200 to 250 ° C., and the content of the resin particles is the smallest among all the inks. The present inventors have found that an image with high gloss can be obtained without bleeding even when an image of a color other than white ink is printed at a location where ink is printed. The detailed reason why the above effect is obtained is unknown, but when a different color ink is ejected onto the white ink by the glycol ether solvent contained in the white ink, the ink is aggregated and thickened on the white ink. As a result, the ink fluidity decreases, and it is estimated that bleeding is suppressed.

That is, the above problem is solved by the following invention 1).
1) In an inkjet ink set comprising white ink and at least two or more colors of ink different from white ink,
All the inks of the two or more colors contain at least water, a water-soluble organic solvent, a pigment, and resin particles,
In addition, the water-soluble organic solvent contained in the white ink contains a glycol ether having a boiling point of 200 ° C. or more and 250 ° C. or less, and the content of the resin particles contained in the white ink is the smallest among all the inks. Ink set.

  ADVANTAGE OF THE INVENTION According to this invention, when printing on white ink, the ink set for inkjets which can obtain an image without a blur and high gloss can be provided.

Schematic which shows an example of the inkjet recording device of this invention. FIG. 2 is an explanatory diagram of an internal structure of the apparatus main body 101 in FIG. 1.

Hereinafter, the present invention 1) will be described in detail. The embodiment of the present invention 1) includes the following 2) to 6), and these will be described together.
2) The ink set for inkjet according to 1), wherein the white ink has a water-soluble organic solvent contained only in the white ink.
3) The inkjet ink set according to 1) or 2), wherein the glycol ether having a boiling point of 200 ° C. or more and 250 ° C. or less is a water-soluble organic solvent contained only in white ink.
4) The ink for ink jet according to any one of 1) to 3), wherein all the inks are composed of 2,3-butanediol and / or propylene glycol in an amount of 50% by mass or more of the water-soluble organic solvent. Ink set.
5) In all the inks, 50% by mass or more of the water-soluble organic solvent is composed of 2,3-butanediol and / or propylene glycol, and further contains 3-methoxy-3-methyl-1-butanol. 4) The inkjet ink set described in 4).
6) Ink jet ink according to any one of 1) to 5) in an ink jet recording method in which white ink is ejected onto a substrate and then ink of a color different from the white ink is ejected onto the ejected white ink. An inkjet recording method, wherein printing is performed using a set.

The ink-jet ink set of the present invention includes white ink and ink of at least two colors composed of inks of different colors from the white ink. Examples of the ink different from the white ink include black ink, magenta ink, cyan ink, yellow ink, light cyan ink, light magenta ink, etc., and white ink, black ink, magenta ink, cyan ink, and yellow ink. Combinations such as a combination of white ink, black ink, magenta ink, cyan ink, yellow ink, light cyan ink, and light magenta ink are preferable.
All the inks of the inkjet ink set of the present invention contain at least a pigment, resin particles, water, and a water-soluble organic solvent. This will be described in detail below.

<Pigment>
The pigment includes an organic pigment and an inorganic pigment, and can be appropriately selected and used depending on the color to be used.
Preferable white pigments include titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide and the like.
As the black pigment, carbon black (Pigment Black 7) is particularly preferable, Regal (registered trademark), Black Pearls (registered trademark), Elftex (registered trademark), Monarch (registered trademark), Regal (registered trademark), Carbon black (for example, Black Pearls 2000, 1400, 1300, 1100, 1000, 900, 880, 800, available from Cabot Corporation under the trademarks Mogul (R) and Vulcan (R) 700, 570, Black Pearls L, Elftex 8, Monarch 1400, 1300, 1100, 1000, 900, 880, 800, 700, Mogu L, Regal 30, the 400, the 660, Vulcan P), SENSIJET BlackSDP100 (SENSIENT), SENSIJET BlackSDP1000 (SENSIENT), SENSIJET BlackSDP2000 (SENSIENT), and the like.

  Examples of color pigments include C.I. I. Pigment Yellow 1, 3, 12, 13, 14, 17, 24, 34, 35, 37, 42 (yellow iron oxide), 53, 55, 74, 81, 83, 95, 97, 98, 100, 101, 104 , 108, 109, 110, 117, 120, 128, 139, 150, 151, 155, 153, 180, 183, 185, 213, C.I. I. Pigment orange 5, 13, 16, 17, 36, 43, 51, C.I. I. Pigment Red 1, 2, 3, 5, 17, 22, 23, 31, 38, 48: 2, 48: 2 (Permanent Red 2B (Ca)), 48: 3, 48: 4, 49: 1, 52: 2, 53: 1, 57: 1 (Brilliant Carmine 6B), 60: 1, 63: 1, 63: 2, 64: 1, 81, 83, 88, 101 (Bengara), 104, 105, 106, 108 ( Cadmium red), 112, 114, 122 (quinacridone magenta), 123, 146, 149, 166, 168, 170, 172, 177, 178, 179, 185, 190, 193, 209, 219, C.I. I. Pigment violet 1 (rhodamine lake), 3, 5: 1, 16, 19, 23, 38, C.I. I. Pigment Blue 1, 2, 15 (phthalocyanine blue), 15: 1, 15: 2, 15: 3 (phthalocyanine blue), 15: 4, 16, 17: 1, 56, 60, 63; I. Pigment green 1, 4, 7, 8, 10, 17, 18, 36, and the like.

  In order to disperse the pigment in the ink, a method of dispersing using a surfactant, a method of dispersing using a dispersible resin, a method of coating and dispersing the surface of the pigment with a resin, a hydrophilic function on the pigment surface And a method of introducing a group into a self-dispersing pigment.

The pigment preferably has a surface area of about 10 to about 1500 m ² / g, more preferably about 20 to about 600 m ² / g, and even more preferably about 50 to about 300 m ² / g.
If the desired surface area is not met, the pigment may be reduced in size or crushed (eg, ball milling, jet milling, or sonication) to reduce the pigment to a relatively small particle size.
In terms of the pigment dispersion stability, ejection stability, image density, and ink productivity of the ink, the volume average particle size (D ₅₀ ) of the pigment in the ink is preferably 10 to 300 nm, more preferably 20 to 250 nm. is there.

  The content of the pigment in the ink is preferably about 0.1 to 10% by mass, more preferably about 1 to 10% by mass in terms of image density, fixability, and ejection stability.

<Resin particles>
In the present invention, resin particles in which a resin is dispersed in water are contained in the ink.
The type of resin particles is not particularly limited and can be appropriately selected according to the purpose. For example, urethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, butadiene resin, styrene-butadiene Resin particles such as resin, vinyl chloride resin, acrylic styrene resin, and acrylic silicone resin. Among these, an emulsion of urethane resin or acrylic resin is preferable because it is excellent in fixability and ink stability. Further, the resin particles may contain a dispersant such as a surfactant as necessary, but since it is easy to obtain an ink having a better coating film performance, so-called self-emulsifying resin particles are obtained. preferable. In that case, from the viewpoint of water dispersibility, it is preferable to contain an anionic group in the range where the acid value is 5 to 100 mgKOH / g, and in order to impart excellent scratch resistance and chemical resistance, 5 to 50 mgKOH / Particularly preferred is mg. Moreover, when a carboxyl group, a sulfonic acid group, etc. are used as said anionic group, favorable water dispersion stability can be obtained. In order to introduce these anionic groups into the resin, a monomer having these anionic groups may be used.

As a resin particle, you may use what was synthesize | combined suitably or may use a commercial item.
Examples of the commercially available products include Superflex 130 (polyether urethane resin particles, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Jongkrill 537 (acrylic resin particles, manufactured by BASF), Microgel E-1002, E-5002 ( Styrene-acrylic resin particles (manufactured by Nippon Paint Co., Ltd.), Boncoat 4001 (acrylic resin particles, manufactured by Dainippon Ink and Chemicals), Boncoat 5454 (styrene-acrylic resin particles, manufactured by Dainippon Ink and Chemicals), SAE -1014 (styrene-acrylic resin particles, manufactured by Nippon Zeon Co., Ltd.), Cybinol SK-200 (acrylic resin particles, manufactured by Seiden Chemical), Primal AC-22, AC-61 (acrylic resin particles, Rohm and Manufactured by Haas Co., Ltd.), Nanocryl SBCX-2821, 3689 (acrylic silicone) Emissions-based resin particles, manufactured by Toyo Ink Mfg. Co., Ltd.), # 3070 (methyl methacrylate polymer resin particles, manufactured by Mikuni Color Ltd.).

  In consideration of the use of the resin particles particularly in an ink jet recording apparatus, the volume average particle size is preferably 10 to 1,000 nm, and more preferably 20 to 50 nm. Here, the volume average particle diameter can be measured using, for example, a particle size analyzer (Microtrac Model UPA9340, manufactured by Nikkiso Co., Ltd.).

  In the present invention, the resin particles contained in the white ink are less than the resin particles contained in other colors, so that no blurring occurs and an excellent image can be formed. Among the inks other than the white ink, the resin particle content of the white ink is preferably 0.1 to 3% by mass lower than the color ink having the lowest resin particle content. The content of the resin particles in the ink of all colors is preferably in the range of 3 to 10% by mass, and high glossiness and ink stability can be obtained.

<Water-soluble organic solvent>
As the water-soluble organic solvent contained in the water-based ink, any water-soluble organic solvent can be used.
Examples thereof include ethylene glycol, propylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 2,3-butanediol, 1,4- Butanediol, 2-methyl-2,4-pentanediol, diethylene glycol, triethylene glycol, dipropylene glycol, 2,2-dimethyl-1,3-propanediol, 2-methyl-1,3-propanediol, 1, Polyhydric alcohols such as 2-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 1,6-hexanediol, 2-ethyl-1,3-hexanediol, 2,5-hexanediol; Dipropylene glycol monomethyl ether, propylene glycol-n-butyl ether Propylene glycol-t-butyl ether, diethylene glycol methyl ether, diethylene glycol ethyl ether, diethylene glycol benzyl ether, ethylene glycol-n-propyl ether, ethylene glycol-n-butyl ether, dipropylene glycol-n-propyl ether, tripropylene glycol methyl ether, tripropylene glycol Propylene glycol-n-propyl ether, propylene glycol phenyl ether, triethylene glycol methyl ether, triethylene glycol methyl ether, triethylene glycol ethyl ether, triethylene glycol butyl ether, diethylene glycol-n-hexyl ether, ethylene glycol phenyl ether, etc. Alkyl alcohol alkyl Ethers; esters such as ethyl lactate; nitrogen-containing heterocyclic compounds such as N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, and ε-caprolactam Amides such as formamide, N-methylformamide, N, N-dimethylformamide; amines such as monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, triethylamine; dimethyl sulfoxide, sulfolane, thiodiethanol, thio And sulfur-containing compounds such as diglycol.
These may be used individually by 1 type and may use 2 or more types together.

Among these, the white ink contains at least one glycol ether having a boiling point of 200 to 250 ° C., thereby promoting aggregation of particles in the ink of a color different from the white ink formed on the white ink. Even in overprinting printing, high-speed printing is possible. Examples of glycol ethers at 200 to 250 ° C. include diethylene glycol ethyl ether (bp 202 ° C., molecular weight 134.2), diethylene glycol monoisopropyl ether (bp 207 ° C., molecular weight 148.2), diethylene glycol monoisobutyl ether (bp 220 ° C., molecular weight 162.2). , Triethylene glycol dimethyl ether (bp 216 ° C., molecular weight 178.2), diethylene glycol monobutyl ether (bp 230 ° C., molecular weight 162.2), tripropylene glycol monomethyl ether (bp 242 ° C., molecular weight 206.3), triethylene glycol monomethyl ether (bp 249) And a molecular weight of 164.2).
Further, among the above glycol ethers, those having a molecular weight of 170 or more are particularly effective in promoting the aggregation of particles in an ink having a color different from that of the white ink formed on the white ink, and form an image having no blur. Is possible.
The content of glycol ether contained in the white ink is preferably 1 to 10% by mass.

The white ink preferably has a water-soluble organic solvent contained only in the white ink.
The glycol ether having at least a boiling point of 200 to 250 ° C. is preferably contained only in the white ink. By being contained only in the white ink, the effect of promoting the aggregation of particles in the ink having a color different from that of the white ink is enhanced.
This is because the ink other than the white ink has a larger aggregation of the ink due to the glycol ether than the white ink. When landing on the white ink, the glycol ether contained in the white ink is replaced with the white ink. By aggregating the different inks above.

  The total amount of the water-soluble organic solvent in the ink is preferably in the range of 20 to 70% by mass, and more preferably in the range of 30 to 60% by mass. If the total amount is 20% by mass or more, it becomes difficult to dry the ink, and it becomes easy to obtain particularly sufficient ejection stability. Moreover, if it is 70 mass% or less, the viscosity of an ink will not become high too much and it is advantageous for discharge.

Moreover, it is preferable to mix propylene glycol (bp 188 ° C.) and / or 2,3-butanediol (bp 183 ° C.) as the water-soluble organic solvent because high gloss can be obtained. The content of these water-soluble organic solvents in the ink is preferably 10 to 50% by mass, and more preferably 20 to 40% by mass.
Furthermore, when a water-soluble organic solvent having a boiling point exceeding 250 ° C. is not included, the drying property is further improved, which is effective.

  Further, when 50% by mass or more of the water-soluble organic solvent contained in the water-based ink is composed of propylene glycol (bp 188 ° C.) and / or 2,3-butanediol (bp 183 ° C.), high gloss can be obtained. Since drying property improves, it is more preferable. Furthermore, by including 3-methoxy-3-methyl-1-butanol, bleeding on white ink is suppressed, and favorable image formation is enabled. The content of 3-methoxy-3-methyl-1-butanol in the ink is preferably 2 to 30% by mass, and more preferably 5 to 20% by mass.

<Other additives>
Examples of other additives added to the ink include surfactants, antiseptic / antifungal agents, rust preventives, pH adjusters and the like.
As the surfactant, any of silicone surfactants, fluorine surfactants, amphoteric surfactants, nonionic surfactants and anionic surfactants can be used.
There is no restriction | limiting in particular as a silicone type surfactant, According to the objective, it can select suitably. Among them, those that do not decompose even at high pH are preferable, and examples thereof include side chain modified polydimethylsiloxane, both terminal modified polydimethylsiloxane, one terminal modified polydimethylsiloxane, and side chain both terminal modified polydimethylsiloxane. Those having an oxyethylene group or a polyoxyethylene polyoxypropylene group are particularly preferred because they exhibit good properties as an aqueous surfactant.
In addition, as the silicone surfactant, a polyether-modified silicone surfactant can be used, and examples thereof include a compound in which a polyalkylene oxide structure is introduced into the side chain of the Si portion of dimethylsiloxane.
Examples of the fluorosurfactant include a perfluoroalkyl sulfonic acid compound, a perfluoroalkyl carboxylic acid compound, a perfluoroalkyl phosphate compound, a perfluoroalkyl ethylene oxide adduct, and a perfluoroalkyl ether group in the side chain. Polyoxyalkylene ether polymer compounds are particularly preferred because of their low foaming properties.
Examples of the perfluoroalkyl sulfonic acid compound include perfluoroalkyl sulfonic acid, perfluoroalkyl sulfonate, and the like.
Examples of the perfluoroalkyl carboxylic acid compound include perfluoroalkyl carboxylic acid and perfluoroalkyl carboxylate.
Examples of the polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain include a sulfate ester salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain, and a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain. Examples thereof include salts of oxyalkylene ether polymers.
As counter ions of the salts in these fluorosurfactants, Li, Na, K, NH ₄ , NH ₃ CH ₂ CH ₂ OH, NH ₂ (CH ₂ CH ₂ OH) ₂ , NH (CH ₂ CH ₂ OH) ₃ etc. are mentioned.

Examples of antiseptic / antifungal agents include 1,2-benzisothiazolin-3-one, sodium benzoate, sodium dehydroacetate, sodium sorbate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, and the like.
Examples of the rust preventive include acidic sulfite, sodium thiosulfate, ammonium thiodiglycolate, diisopropyl ammonium nitrite, pentaerythritol tetranitrate, dicyclohexyl ammonium nitrite and the like.

  The pH adjuster is not particularly limited as long as it can adjust the pH to a desired value without adversely affecting the ink to be prepared. Examples include hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide, and potassium hydroxide; alkali metal carbonates such as lithium carbonate, sodium carbonate, and potassium carbonate; quaternary ammonium hydroxides, Examples include amines such as diethanolamine and triethanolamine; ammonium hydroxide and quaternary phosphonium hydroxide.

  The ink of the present invention can be prepared by adding water to each of the above components and stirring and mixing as necessary. Stirring and mixing can be performed with a stirrer using a normal stirring blade, a magnetic stirrer, a high-speed disperser or the like. However, the production method is not particularly limited, and a known method may be adopted as appropriate. The total amount of water in the ink is preferably in the range of 20 to 70% by mass, and more preferably in the range of 30 to 60% by mass.

<Inkjet recording method>
The ink jet recording method of the present invention includes at least a step of ejecting ink of a color different from the white ink onto the ejected white ink after ejecting the white ink onto the substrate.
The ink ejection process is a process for printing by applying a stimulus to ink and causing it to fly. There is no restriction | limiting in particular as a means to fly this ink, According to the objective, it can select suitably, For example, various recording heads (ink discharge head) are mentioned. In particular, it is preferable to have a head having a plurality of nozzle rows and a sub tank that stores ink supplied from an ink cartridge and supplies ink to the head. The sub tank includes negative pressure generating means for generating a negative pressure in the sub tank, atmospheric release means for releasing the inside of the sub tank to the atmosphere, and detection means for detecting the presence or absence of ink based on a difference in electrical resistance. What has is preferable.

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

There is no particular limitation on the mode of the ink flight, and it varies depending on the type of the stimulus. For example, when the stimulus is “heat”, the thermal energy corresponding to the recording signal is applied to the ink in the recording head. For example, there is a method in which a thermal head or the like is applied, bubbles are generated in the ink by the thermal energy, and ink is ejected and ejected as droplets from the nozzle holes of the recording head by the pressure of the bubbles. Further, when the stimulus is “pressure”, for example, by applying a voltage to a piezoelectric element bonded to a position called a pressure chamber in an ink flow path in the recording head, the piezoelectric element bends and the volume of the pressure chamber is increased. And a method of ejecting and ejecting ink as droplets from the nozzle holes of the recording head.
Among them, a method of applying a voltage to the piezo element and causing the ink to fly is preferable. Since the piezo method does not generate heat, it is advantageous for flying ink containing resin, and is an effective method with less nozzle clogging, particularly when ink containing a small amount of wetting agent is used. In order to prevent nozzle omission, it is preferable to perform a blank scan by applying a voltage having a strength that does not eject ink to the piezo element. Furthermore, it is preferable to perform an operation of discharging ink to the ink reservoir before reaching the empty scan for one page printing. Further, it is preferable to have a scraping means for scraping off the ink fixed to the empty discharge receptacle. As the scraping means, either a wiper or a cutter is preferable.

In the present invention, a heating device for heating the substrate may be provided in order to increase the spread of the discharged white ink or ink of a different color from the white ink on the substrate and the white ink coating film. Is possible.
As the heating means, one or more can be used by appropriately selecting from many known heating apparatuses. Examples of the heating device include devices for forced air heating, radiation heating, conduction heating, high frequency drying, and microwave drying. Such a heating device may be incorporated into an existing inkjet printer or may be externally attached to an existing inkjet printer.

FIG. 1 is a schematic view showing an example of an ink jet recording apparatus using the ink jet recording method of the present invention. The following description corresponds to a serial type (shuttle type) ink jet recording apparatus scanned by a carriage, but the apparatus of the present invention can also be applied to a line type ink jet recording apparatus having a line type head.
The apparatus of FIG. 1 includes an apparatus main body 101, a paper feed tray 102 for loading a base material mounted on the apparatus main body 101, and a paper discharge tray 103 for stocking the printed base material mounted on the apparatus main body 101. And an ink cartridge loading unit 104. On the upper surface of the ink cartridge loading unit 104, an operation unit 105 such as operation keys and a display is arranged. The ink cartridge loading unit 104 has a front cover 115 that can be opened and closed for attaching and detaching the ink cartridge 200. Reference numeral 111 denotes an upper cover, and reference numeral 112 denotes a front surface of the front cover.

In the apparatus main body 101, as shown in FIG. 2, there are guide rods 131 and stays 132 which are horizontally mounted on left and right side plates (not shown), and the carriage 133 is slidable in the main scanning direction. It is held and moved and scanned by a main scanning motor (not shown).
The carriage 133 has a recording head 134 composed of five inkjet recording heads that eject ink droplets of each color of yellow (Y), cyan (C), magenta (M), black (Bk), and white (W). With the plurality of ink ejection openings arranged in a direction intersecting with the main scanning direction, the ink droplet ejection direction is mounted downward.
As the ink jet recording head constituting the recording head 134, a piezoelectric actuator such as a piezoelectric element, a thermal actuator using phase change due to liquid film boiling using an electrothermal transducer such as a heating resistor, a metal phase due to temperature change, etc. A shape memory alloy actuator that uses a change, an electrostatic actuator that uses an electrostatic force, or the like as a stimulus generating means for ejecting ink can be used. Further, a heater mechanism for heating the ink in the recording head may be provided.
In addition, the carriage 133 is equipped with a sub tank 135 for each color for supplying ink of each color to the recording head 134. The sub tank 135 is supplied with ink from the ink cartridge 200 loaded in the ink cartridge loading unit 104 via an ink supply tube (not shown) and is replenished.

On the other hand, the substrate 142 is separated and fed one by one from the substrate stacking unit 141 as a sheet feeding unit for feeding the substrate 142 loaded on the substrate loading unit (pressure plate) 141 of the sheet feeding tray 102. Opposite the half-moon roller [paper feed roller 143] and the paper feed roller 143, a separation pad 144 made of a material having a large friction coefficient is provided, and this separation pad 144 is urged toward the paper feed roller 143 side.
As a transport unit for transporting the base material 142 fed from the paper feed unit on the lower side of the recording head 134, a transport belt 151 for electrostatically attracting and transporting the base material 142, and a paper feed unit On the conveyor belt 151, the counter roller 152 for transporting the base material 142 fed through the guide 145 with the transport belt 151 being sandwiched between the counter roller 152 and the base material 142 fed substantially vertically upward is changed by about 90 °. And a leading end pressure roller 155 urged toward the conveyor belt 151 by a pressing member 154, and charging as charging means for charging the surface of the conveyor belt 151. A roller 156 is provided.

  The conveyance belt 151 is an endless belt, is stretched between the conveyance roller 157 and the tension roller 158, and can circulate in the belt conveyance direction. The transport belt 151 includes, for example, a surface layer serving as a substrate adsorption surface formed of a resin material having a thickness of about 40 μm that is not subjected to resistance control (for example, a copolymer of tetrafluoroethylene and ethylene (ETFE)), It has the same material as the surface layer and a back layer (medium resistance layer, earth layer) that has been subjected to resistance control by carbon. On the back side of the conveyance belt 151, a guide member 161 is arranged corresponding to a printing area by the recording head 134. Note that, as a paper discharge unit for discharging the base material 142 recorded by the recording head 134, a separation claw 171 for separating the base material 142 from the transport belt 151, a paper discharge roller 172, and a paper discharge roller 173, The base material 142 is dried with hot air by the fan heater 174 and then output to the paper discharge tray 103 below the paper discharge roller 172.

A double-sided paper feeding unit 181 is detachably mounted on the back surface of the apparatus main body 101. The double-sided paper feeding unit 181 takes in the base material 142 returned by the reverse rotation of the transport belt 151, reverses it, and feeds it again between the counter roller 152 and the transport belt 151. A manual paper feed unit 182 is provided on the upper surface of the duplex paper feed unit 181.
In this ink jet recording apparatus, the base material 142 is separated and fed one by one from the paper feed unit, and the base material 142 fed substantially vertically upward is guided by the guide 145, and the conveyance belt 151, the counter roller 152, It is sandwiched between and conveyed. Further, the leading end is guided by the conveying guide 153 and pressed against the conveying belt 151 by the leading end pressure roller 155, and the conveying direction is changed by approximately 90 °. At this time, the conveyance belt 151 is charged by the charging roller 156, and the base material 142 is electrostatically attracted to the conveyance belt 151 and conveyed. Therefore, by driving the recording head 134 according to the image signal while moving the carriage 133, ink droplets are ejected onto the stopped base material 142 to record one line, and the base material 142 is conveyed by a predetermined amount. After that, the next line is recorded. When recording different color inks on the white ink, after ejecting white ink droplets onto the stopped base material 142 to record one line, continue to apply different inks other than the white ink onto the white ink. It is also possible to transport the base material 142 by a predetermined amount after recording one line. Upon receiving a recording end signal or a signal that the rear end of the base material 142 has reached the recording area, the recording operation is finished and the base material 142 is discharged onto the paper discharge tray 103.

The substrate to be printed with the ink jet recording method of the present invention is a non-porous substrate. Here, the non-porous substrate is a resin having a surface made of a non-porous material such as a transparent or colored polyvinyl chloride film, a polyethylene terephthalate (PET) film, an acrylic film, a polypropylene film, a polyimide film, or a polystyrene film. Films, laminate papers, coated papers, and the like, which are made of paper containing no paper components such as wood pulp paper, Japanese paper, synthetic pulp paper, and synthetic fiber paper.
The ink jet recording method of the present invention can be applied to various types of recording by the ink jet recording method, and is particularly preferably applied to, for example, an ink jet recording printer, a facsimile apparatus, a copying apparatus, a printer / fax / copier multifunction machine, and the like. Can do.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated further more concretely, this invention is not limited at all by these Examples. In the examples, “%” is “mass%”.

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

-Preparation of black pigment-containing polymer fine particle dispersion-
After sufficiently stirring 28 g of polymer solution A, 42 g of carbon black (manufactured by Degussa, FW100), 13.6 g of 1 mol / L potassium hydroxide aqueous solution, 20 g of methyl ethyl ketone, and 13.6 g of water, using a roll mill Kneaded. The obtained paste was put into 200 g of pure water and stirred sufficiently, and then the methyl ethyl ketone and water were distilled off with an evaporator, and this dispersion was further removed from the polyvinylidene fluoride membrane having an average pore size of 5.0 μm to remove coarse particles. The mixture was filtered under pressure to obtain a black pigment-containing polymer fine particle dispersion having a pigment solid content of 15% and a solid content concentration of 20%.

<Preparation of magenta, cyan, yellow pigment-containing polymer fine particle dispersion>
Magenta, cyan, and yellow pigment-containing polymer fine particle dispersions were obtained in the same manner except that the carbon black used in the preparation of the black pigment-containing polymer fine particle dispersion was changed as follows.
Magenta: Pigment Red 122 manufactured by Sun Chemical
Cyan: Copper phthalocyanine pigment manufactured by Toyo Ink Co., Ltd.
(C.I. Pigment Blue 15: 4, trade name: LX4033)
Yellow: Yellow pigment manufactured by Dainichi Seika Kogyo Co., Ltd.
(Pigment Yellow 74, trade name: Yellow No. 46)

<Preparation of white pigment dispersion>
25 g of titanium oxide STR-100W (manufactured by Sakai Chemical Industry Co., Ltd.), 5 g of pigment dispersant TEGO Dispers651 (manufactured by Evonik Co., Ltd.) and 70 g of water are mixed and 0 in a bead mill (Research Lab, manufactured by Shinmaru Enterprises Co., Ltd.). .3 mmΦ zirconia beads were dispersed at a filling rate of 60% and 8 m / s for 5 minutes to obtain a white pigment dispersion.

[Example 1]
After mixing and stirring the materials of the following formulation, the mixture was filtered through a 0.2 μm polypropylene filter to prepare an ink.
(black)
-Black pigment-containing polymer fine particle dispersion (solid content 20%, solvent: water) 20%
・ Polyether urethane resin particles Superflex 130
(Daiichi Kogyo Seiyaku Co., Ltd., solid content 35%, solvent: water) 20%
Surfactant CH ₃ (CH ₂ ) ₁₂ O (CH ₂ CH ₂ O) ₃ CH ₂ COOH 2%
・ 2,3-butanediol 30%
3-methoxy-3-methyl-1-butanol 10%
・ Water 17.9%
-Antiseptic / antifungal agent Proxel LV (Avisia) 0.1%

(Magenta)
-Magenta pigment-containing polymer fine particle dispersion (solid content 20%, solvent: water) 20%
・ Polyether urethane resin particles Superflex 130
(Daiichi Kogyo Seiyaku Co., Ltd., solid content 35%, solvent: water) 20%
Surfactant CH ₃ (CH ₂ ) ₁₂ O (CH ₂ CH ₂ O) ₃ CH ₂ COOH 2%
・ 2,3-butanediol 30%
3-methoxy-3-methyl-1-butanol 10%
・ Water 17.9%
-Antiseptic / antifungal agent Proxel LV (Avisia) 0.1%

(cyan)
-Cyan pigment-containing polymer fine particle dispersion (solid content 20%, solvent: water) 20%
・ Polyether urethane resin particles Superflex 130
(Daiichi Kogyo Seiyaku Co., Ltd., solid content 35%, solvent: water) 20%
Surfactant CH ₃ (CH ₂ ) ₁₂ O (CH ₂ CH ₂ O) ₃ CH ₂ COOH 2%
・ 2,3-butanediol 30%
3-methoxy-3-methyl-1-butanol 10%
・ Water 17.9%
-Antiseptic / antifungal agent Proxel LV (Avisia) 0.1%

(yellow)
・ Yellow pigment-containing polymer fine particle dispersion (solid content 20%, solvent: water) 20%
・ Polyether urethane resin particles Superflex 130
(Daiichi Kogyo Seiyaku Co., Ltd., solid content 35%, solvent: water) 20%
Surfactant CH ₃ (CH ₂ ) ₁₂ O (CH ₂ CH ₂ O) ₃ CH ₂ COOH 2%
・ 2,3-butanediol 30%
3-methoxy-3-methyl-1-butanol 10%
・ Water 17.9%
-Antiseptic / antifungal agent Proxel LV (Avisia) 0.1%

(white)
・ White pigment dispersion (solid content 25%, solvent: water) 25%
・ Polyether urethane resin particles Superflex 130
(Daiichi Kogyo Seiyaku Co., Ltd., solid content 35%, solvent: water) 15%
Surfactant CH ₃ (CH ₂ ) ₁₂ O (CH ₂ CH ₂ O) ₃ CH ₂ COOH 2%
・ 2,3-butanediol 30%
・ 3-methoxy-3-methyl-1-butanol 5%
・ Tripropylene glycol monomethyl ether (bp242 ° C) 5%
・ Water 17.9%
-Antiseptic / antifungal agent Proxel LV (Avisia) 0.1%

Ink jet printer (Ricoh Co., Ltd. IPSiO GXe5500 remodeling machine) remodeled so that it can be mounted with the above black, magenta, cyan, yellow and white ink sets is filled with ink and transparent PET with non-porous substrate On a sheet LLPET 1223 (manufactured by Sakurai Co., Ltd.), a test pattern in which a solid image of four colors was adjacent to a solid image of white ink was printed.
The bleeding and gloss of the obtained image were evaluated according to the following criteria. The results are shown in Table 3.

<Bleeding evaluation>
The test pattern was measured by the degree of bleeding when visually observed.
Evaluation A No occurrence of bleeding Evaluation B Very slight bleeding is confirmed in some black and yellow areas Evaluation C Bleeding is confirmed in the entire black and yellow boundary area Evaluation D Bleeding is observed in the entire belt-like pattern Occurrence of

<Glossy evaluation>
The 60 ° glossiness of the black solid image was measured with a glossmeter (BYK Gardener, 4501). The higher the gloss value, the better the gloss.

[Examples 2 to 15]
The black, magenta, cyan, yellow and white inks of Example 1 were printed using an ink jet printer in the same manner as in Example 1 except that the ink set shown in Table 1 was changed.
In Tables 1 and 2, the numerical value of each material used for the prescription indicates a blending ratio “mass%”. The resin emulsion is “polyether-based urethane resin particle Superflex 130 (Daiichi Kogyo Seiyaku Co., Ltd., solid content 35%, solvent: water)” used in Example 1.

[Example 16]
After mixing and stirring the materials of the following formulation, the mixture was filtered through a 0.2 μm polypropylene filter to prepare an ink.
(Light magenta)
・ Magenta pigment-containing polymer fine particle dispersion (solid content 20%, solvent: water) 8%
・ Polyether-based urethane resin particles Superflex 130
(Daiichi Kogyo Seiyaku Co., Ltd., solid content 35%, solvent: water) 20%
Surfactant CH ₃ (CH ₂ ) ₁₂ O (CH ₂ CH ₂ O) ₃ CH ₂ COOH 2%
・ 2,3-butanediol 30%
3-methoxy-3-methyl-1-butanol 10%
・ Water 29.9%
-Antiseptic / antifungal agent Proxel LV (Avisia) 0.1%

(Light cyan)
Cyan pigment-containing polymer fine particle dispersion (solid content 20%, solvent: water) 8%
・ Polyether-based urethane resin particles Superflex 130
(Daiichi Kogyo Seiyaku Co., Ltd., solid content 35%, solvent: water) 20%
Surfactant CH ₃ (CH ₂ ) ₁₂ O (CH ₂ CH ₂ O) ₃ CH ₂ COOH 2%
・ 2,3-butanediol 30%
3-methoxy-3-methyl-1-butanol 10%
・ Water 29.9%
-Antiseptic / antifungal agent Proxel LV (Avisia) 0.1%

To the above-described ink jet printer (Ricoh Co., Ltd. IPSiO GXe5500 remodeling machine) modified so that the light magenta, light cyan ink, and the ink set of black, magenta, cyan, yellow ink and white ink prepared in Example 1 can be mounted. A test pattern in which a solid image of six colors was adjacent to a solid image of white ink was printed on a transparent PET sheet LLPET1223 (manufactured by Sakurai Co., Ltd.), which was a non-porous substrate, with ink filled.
The bleeding and gloss of the obtained image were evaluated in the same manner as in Example 1.

[Examples 17 to 18]
The black, magenta, cyan, yellow and white inks of Example 1 were printed using an ink jet printer in the same manner as in Example 1 except that the ink set shown in Table 1 was changed.

[Comparative Examples 1-4]
The black, magenta, cyan, yellow and white inks of Example 1 were printed using an ink jet printer in the same manner as in Example 1 except that the ink set shown in Table 2 was changed.

The following characteristics evaluation was performed about each ink of the said Examples 1-16 and Comparative Examples 1-4. The results are shown in Table 3.

  As can be seen from the results in Table 3 above, the inkjet ink set of the present invention was able to obtain images with high gloss and no bleeding on any of the white ink coating films.

DESCRIPTION OF SYMBOLS 101 Main body 102 Paper feed tray 103 Paper discharge tray 104 Ink cartridge loading part 105 Operation part 111 Upper cover 112 Front face 115 Front cover 131 Guide rod 132 Stay 133 Carriage 134 Recording head 135 Sub tank 141 Substrate loading part 142 Base material 143 Paper feed Roller 144 Separation pad 145 Guide 151 Conveying belt 152 Counter roller 153 Conveying guide 154 Pressing member 155 Pressing roller 156 Charging roller 157 Conveying roller 158 Densation roller 161 Guide member 171 Separating claw 172 Discharging roller 173 Discharging roller 174 Fan heater 181 Double-sided paper feed unit 182 Manual paper feed unit 200 Ink cartridge

JP 2005-220352 A JP 2011-094082 A JP 2011-201230 A

Claims (6)

In an inkjet ink set including white ink and at least two or more colors of ink different from white ink,
All the inks of the two or more colors contain at least water, a water-soluble organic solvent, a pigment, and resin particles,
In addition, the water-soluble organic solvent contained in the white ink contains a glycol ether having a boiling point of 200 ° C. or more and 250 ° C. or less, and the content of the resin particles contained in the white ink is the smallest among all the inks. Ink-jet ink set.   The inkjet ink set according to claim 1, wherein the white ink has a water-soluble organic solvent contained only in the white ink.   The inkjet ink set according to claim 1 or 2, wherein the glycol ether having a boiling point of 200 ° C or higher and 250 ° C or lower is a water-soluble organic solvent contained only in white ink.   The ink set for inkjet according to any one of claims 1 to 3, wherein 50% by mass or more of the water-soluble organic solvent is composed of 2,3-butanediol and / or propylene glycol. .   In all the inks, 50% by mass or more of the water-soluble organic solvent is composed of 2,3-butanediol and / or propylene glycol, and further contains 3-methoxy-3-methyl-1-butanol. The inkjet ink set according to claim 4.   The inkjet ink set according to any one of claims 1 to 5, wherein the inkjet ink set according to any one of claims 1 to 5 is an inkjet recording method in which an ink of a color different from the white ink is ejected onto the ejected white ink after ejecting the white ink onto the substrate. An ink jet recording method, wherein printing is performed using the ink jet recording method.

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