JP6260371B2 - Ink jet ink, ink cartridge using the ink, and image recording apparatus - Google Patents

Description

  The present invention relates to an ink suitable for forming an image on a transparent recording medium and a colored recording medium.

Ink jet printers have advantages such as low noise, low running cost, and easy color printing, and are therefore widely used as digital signal output devices in general households.
In recent years, it is used not only for home use but also for industrial use such as a display, a poster, and a bulletin board.
However, in the case of industrial use, the recording medium is not limited to paper and is widely used from transparent to colored. When expressing white on these media or coloring with color ink, it is necessary to conceal the transparency and coloring of the recording medium with ink and sufficiently conceal the color of the recording medium with ink.

Therefore, white ink is used to express white on a transparent recording medium or a colored recording medium. In addition, since color ink is used in common with ink used for general recording media (recording media having ink absorptivity), white ink is printed as the background of the color ink to increase the hiding power on the recording media. This improves the color development.

In such a white ink, titanium oxide having a high refractive index and a high degree of whiteness is used as a color material. Titanium oxide is an inorganic pigment, and since it has an ionic surface, it is easily compatible with water, facilitates adsorption of a water-soluble pigment dispersant, and has an advantage of being easily dispersed when used in aqueous ink.

However, since titanium oxide has a large specific gravity with respect to water, it tends to settle, and if the viscosity of the ink-jet ink is small, the sedimentation speed increases and separation proceeds in a few days.
In order to obtain whiteness, the average particle diameter of the pigment is preferably 200 to 300 nm in order to facilitate scattering of visible light. Particles with such a particle size have a larger particle size than colloidal particles, so that diffusion of particles due to Brownian motion is unlikely to occur, and since the surface area with respect to the particle weight decreases, the charge due to ionicity on the particle surface Less rebound and easy to settle.
Even if the particles are dispersed stably, the dispersed pigment particles are dispersed in the closest packing because of being dispersed mainly in the charge repellent substance, and a hard cake is formed and the redispersibility is lost.

For these reasons, the use of hollow particles having a small weight per particle volume as a white pigment has been studied. In the ink, hollow particles contain water and a solvent component of ink in the hollow, have a light specific gravity with respect to the volume per particle diameter, and have good dispersibility.

As hollow particles, there are organic products made of resins and inorganic products made of metal oxides. For example, Patent Document 1 discloses one in which inorganic hollow particles made of a metal oxide are applied to a photocurable ink that is used for inkjet.
However, such hollow particles are hardened in a form filled with the monomer contained in the ink when photocured because the solvent in the ink enters the hollow interior, and does not show whiteness.

Patent Document 2 discloses a water-based ink in which hollow resin particles and inorganic hollow particles are used in combination. However, if the ink contains a high boiling point solvent, the drying of the solvent in the hollow becomes slow and it takes time to develop the whiteness, so the whiteness continues to change during the period from printing to the drying of the hollow particles. End up.

An object of the present invention is to provide an aqueous ink using inorganic hollow particles having improved dispersion stability and whiteness stability.

The above-mentioned problem is the “ink for forming an image on a recording medium of the present invention, and the ink contains at least water, a water-soluble organic solvent, inorganic hollow particles, and resin solid particles. This is solved by an “ink-jet ink characterized by comprising only a solvent having a boiling point of 250 ° C. or lower”.

As will be understood from the following detailed and specific description, according to the present invention, an aqueous ink using inorganic hollow particles and having improved dispersion stability and whiteness stability can be provided.

It is the schematic which shows an example of the ink cartridge of this invention. FIG. 7 is a schematic diagram illustrating a modification of the ink cartridge in FIG. 1. It is the schematic which shows an example of the inkjet recording device of this invention. FIG. 3 is an enlarged schematic view of an image forming unit of the ink jet recording apparatus.

The present invention relates to the ink-jet ink shown in the following (1), but embodiments of the invention also include the following (2) to (7).
(1) An ink for forming an image on a recording medium, and the ink contains at least water, a water-soluble organic solvent, inorganic hollow particles, and resin solid particles, and the water-soluble organic solvent has a boiling point of 250 ° C. An ink-jet ink comprising only the following solvent.
(2) The inkjet ink as described in (1) above, further comprising resin hollow particles.
(3) The inkjet ink according to (1) or (2), further comprising organic white pigment particles, wherein the organic white pigment particles are non-hollow.
(4) The inkjet ink according to any one of (1) to (3) above, wherein the water-soluble organic solvent contains 50% by mass or more of a component having a boiling point of 200 ° C. or less.
(5) In the above item (4), the water-soluble organic solvent component having a boiling point of 200 ° C. or less contains 3-methoxy-3-methyl-1-butanol and / or 2,3-butanediol. The inkjet ink as described.
(6) An ink cartridge comprising the inkjet ink according to any one of (1) to (5).
(7) An image recording apparatus including an ink cartridge containing ink and a recording head for discharging ink, wherein the ink is the ink according to any one of (1) to (5). An ink jet type image recording apparatus.

The ink used in the present invention includes only water, inorganic hollow particles, resin solid particles, and a water-soluble organic solvent having a boiling point of 250 ° C. or lower as an image recording ink for forming an image by attaching the ink on a recording medium. It is composed of
By using the inorganic hollow particles in the water-based ink, it is possible to suppress the expression of whiteness and the precipitation of the pigment component, and to achieve both the whiteness coloring property and the storage stability of the ink.

In recent years, volatile organic compounds (hereinafter sometimes referred to as “VOC”) have been regarded as problems. VOC is a general term for organic chemical substances that readily volatilize in the atmosphere at normal temperature and pressure. From the definition of WHO, a volatile organic compound in a narrow sense indicates an organic solvent having a boiling point of 50 ° C to 260 ° C.
VOC emissions from paints, cleaning agents, adhesives, and inks account for 75% of the total sources of VOC emissions, and even by industry, there are many emissions from industries that handle a lot of paint. Conventionally, inkjet inks that form good images on non-porous substrates have been solvent inks containing a volatile organic solvent as the main solvent, so that many VOCs derived from the ink have been generated with printing.

The ink of the present invention can reduce the amount of organic matter generated at the time of drying by using water as a solvent, and can reduce VOC as compared with ether-based solvent-based printing used for printing on a non-porous substrate.
Furthermore, by not containing a water-soluble organic solvent having a boiling point of 250 ° C. or higher, it is possible to improve the drying property of the organic solvent remaining in the inorganic hollow particles and the resin hollow particles, and to increase the whiteness expression rate. It becomes possible.
Further, the amount of heater heat in the drying process can be reduced, and the amount of organic solvent remaining in the ink coating film after drying can be reduced, so that the scratch resistance and solvent resistance of the ink coating film can be improved. . By including resin solid particles in the ink, the ink exhibits a function of fixing a white pigment to a non-porous substrate even if it is an aqueous ink.

Furthermore, when the water-soluble organic solvent used in the ink contains 50% by mass or more of a component having a boiling point of 200 ° C. or less, the scratch resistance can be further improved, and the coating film characteristics can be improved and the heater can be improved. The amount of energy required for drying due to a decrease in temperature can be reduced.
By using an ink containing at least one of 3-methoxy-3-methyl-1-butanol and 2,3-butanediol as such a water-soluble organic solvent, the affinity with the water of the ink is increased, and the moisture retention power is increased. improves. For this reason, it is possible to suppress the drying of the ink in the ink jet head and to suppress the nozzle failure such as the discharge bending or the non-discharge.

By using such an ink and a drying method, it is possible to propose a recording method for forming a good image on a non-porous substrate with low energy generation and low energy, and an image recording apparatus using this recording method By providing this, it is possible to provide a favorable image quality for the non-porous substrate with a low load on the environment.

Embodiments of the present invention will be described below.
The ink used in the present invention is an ink used for image recording in which an ink is attached to a recording medium to form an image, and is composed of water, inorganic hollow particles, resin solid particles, and a water-soluble organic solvent having a boiling point of 250 ° C. or less. It is configured.

First, the color material used in the present invention will be described.
The hollow particle in the present invention is a structure in which a central space is a fluid such as a gas or a liquid and the outside thereof is covered with a solid, and is not a general core-shell structure in which the central part of the particle is a solid.

In the ink of the present invention, the inside of the inorganic hollow particles or resin hollow particles becomes a gas through a drying process, and the difference in refractive index with the encapsulating solid is expressed to cause light scattering and appear white. Improves whiteness. Therefore, sufficient whiteness cannot be obtained with a core-shell resin in which the core portion does not replace gas.

<Inorganic hollow particles>
The inorganic hollow particles used in the inkjet recording ink of the present invention (hereinafter sometimes simply referred to as “ink”) are desired to have a white shell material. Oxynitrides are preferred.
Examples include titanium, silicon, aluminum, zirconium, strontium oxides, nitrides, and oxynitrides. Among these, titanium dioxide and zirconium dioxide are preferred from the viewpoint of refractive index, and the workability of the particles. To silicon dioxide are preferred. Since inorganic hollow particles are difficult to hollow, silicon dioxide is desirable because it has a good balance between availability and performance.

In addition, since it is desired that the ink does not precipitate or float and separate, it is preferable to have a specific gravity approximately equal to that of the ink liquid. However, since the specific gravity of the inorganic substance is heavier than that of the resin, it is preferable to reduce the relative weight of the inorganic substance and reduce the specific gravity of the particles by increasing the hollow ratio and reducing the thickness of the shell.

Moreover, since the influence of Brownian motion becomes smaller and the particles are more likely to settle as the particles become larger, the sedimentation can be suppressed as the particle size of the inorganic hollow particles is reduced. However, in order to express whiteness, a particle size of 200 nm or more is required as secondary particles. Therefore, the particle size of the secondary particles is preferably 200 nm or more and less than 800 nm.

The smaller the primary particles of such inorganic hollow particles, the more stable the dispersibility. However, since there is a limit to reducing the thickness of the shell, it is better to be reasonably large, and the refraction of primary particles is better than the refraction of secondary aggregates. Therefore, the primary particle size is preferably 40 nm or more and 200 nm.
The particle size of these particles can be observed and measured with a transmission electron microscope for dry powders or primary particles, and with a reflection electron microscope for secondary particles, or particles based on the dynamic light scattering method when dispersed in a solvent. It can be measured with a particle size distribution meter using a diameter distribution measuring device.

The content of the inorganic hollow particles in the ink is preferably 3% by mass or more and 10% by mass or less, and more preferably 4.5 to 8% by mass. When the content is 3% by mass or more, sufficient whiteness and scratch resistance are obtained, and when the content is 10% by mass or less, sufficient coating strength is obtained, and good discharge stability is obtained.

The inorganic hollow particles used in the present invention are not particularly limited, but those produced by a known technique can be used.
For example, as described in Japanese Patent No. 4654428, production using silica carbonate as a core material to produce silica by coating alkoxysilane on the surface in an alkaline atmosphere and dissolving calcium carbonate in an acid atmosphere Hollow silica obtained by the method is known and marketed. This can be obtained as Sirinax (manufactured by Nippon Steel Mining Co., Ltd.), Nano Balloon XG40, XR100, XP200 (Grandex Co., Ltd.).

Also, using polyvinyl pyrrolidone (PVP) as a dispersant, polystyrene latex is dispersed in a water ethanol mixture, titanium tetrabutoxide is precipitated on the surface of the polystyrene, and baked at 600 ° C. to form inorganic hollow particles of titanium oxide. It is known to get.

Also known is a method in which zinc nitrate is adsorbed on the polystyrene surface by a similar method and calcined to obtain inorganic hollow particles of zinc oxide.

<Resin hollow particles>
Since it is desired that the hollow resin particles used in the ink for ink jet recording of the present invention do not precipitate or float and separate in the ink, those having a specific gravity substantially equal to the specific gravity of the ink liquid are preferable.

When using solid resin particles that do not have a hollow structure, it is necessary to match the specific gravity of the resin particles to the ink liquid in order to avoid sedimentation of the particles. Since it is necessary to adjust, it is necessary to comprehensively carry out the study of the resin composition, the control of the polymerization (crosslinking) reaction and the control of the particle size, which raises the technical barrier.
On the other hand, if hollow resin particles are used, the portion that was hollow at the time of drying is filled with ink (vehicle) in the ink, so that the density of the hollow resin particles can be regarded as almost the same as that of the ink, and sedimentation occurs. More suppressed.

Examples of the resin composition of the hollow resin particles used in the present invention include acrylic resins such as acrylic resins, styrene-acrylic resins, and cross-linked styrene-acrylic resins, urethane resins, maleic resins, and the like.

These hollow resin particles may be used alone or in combination. The particle size of the hollow resin particles is preferably 0.2 μm to 1.0 μm, considering the concealment of the printed image and not causing clogging in the ink flow path or inkjet head in the image forming apparatus. Is more preferably 0.3 μm to 0.8 μm.

The hollow resin particles used in the present invention are not particularly limited, and known ones can be used.
Examples of commercially available hollow resin particles include MH5055 (manufactured by Nippon Zeon Co., Ltd.), Ropaque OP-62, OP-84J, OP-91, HP-1055, and the like as styrene-acrylic resins. HP-91, ULTRA (made by Rohm and Haas).
Further, as the cross-linked styrene-acrylic resin, SX-863 (A), SX-864 (B), SX-866 (A), SX-866 (B), SX-868 (above, manufactured by JSR Corporation) ) And the like.

<Organic white pigment>
As the organic white pigment used in the present invention, an alkylene bismelamine pigment represented by the following general formula (I) is preferably used.

（ただし、一般式（Ｉ）中、Ｒは水素原子または炭素数１〜４のアルキル基または炭素数５〜７の飽和または不飽和の脂環式基を表す。Ｒ１〜Ｒ４は同一かまたは異なる水素原子または炭素数１〜４の低級アルキル基を表し、Ｒ_１，Ｒ_２またはＲ_３、Ｒ_４が窒素原子と共に複素環式基を形成しても良い。Ｘは炭素数２、３のアルキレン基を表す。）

(In the general formula (I), R represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or a saturated or unsaturated alicyclic group having 5 to 7 carbon atoms. R1 to R4 are the same or different. Represents a hydrogen atom or a lower alkyl group having 1 to 4 carbon atoms, and R ₁ , R _2, R ₃ , and R ₄ may form a heterocyclic group together with a nitrogen atom, X is an alkylene having 2 or 3 carbon atoms Represents a group.)

In the general formula (I), specifically, R represents a hydrogen atom, the alkyl group includes a methyl group, an ethyl group, a propyl group, and a butyl group. The alicyclic group includes a cyclohexyl group and the like. Is mentioned.
Examples of R ₁ , R ₂ , R _3, and R ₄ include a hydrogen atom, a methyl group, an ethyl group, a propyl group, and a butyl group. R ₁ and R ₂ , or R ₃ and R ₄ are nitrogen atoms. A heterocyclic group may be formed together with, for example, a piperidyl group, a morpholino group and the like.
Examples of X include an ethylene group and a propylene group.

In the organic white pigment represented by the general formula (I), specific structures that can be particularly preferably used include R, R ₁ , R ₂ , R ₃ and R ₄ as a hydrogen atom, and X as an ethylene group. It is an organic white pigment represented by the following structural formula (II) and is commercially available as Shigenox OWP (Hackol Chemical Co., Ltd.).

The organic white pigment preferably has a particle size of 0.01 to 0.30 μm. When it is 0.01 μm or more, the particle diameter does not approach the dye, and light resistance and feathering do not deteriorate. Further, when the thickness is 0.30 μm or less, the discharge port is not clogged or clogged with a filter in the printer does not occur, and discharge stability can be obtained.

<Titanium dioxide>
The ink of the present invention can be used in combination with titanium dioxide as a color material in consideration of the sedimentation property of the color material of the ink.

In ink jet recording, since it is difficult to make the coating film thick, it is necessary to provide sufficient whiteness with a thin coating film formed with a small amount of liquid. For this reason, it is preferable to use a material whose whiteness is likely to increase.

The crystal system of titanium dioxide used may be either a rutile type or an anatase type, but a rutile type that has a high refractive index and easily increases whiteness is preferred.
Further, the average primary particle diameter of titanium dioxide is preferably 100 to 400 nm, and the whiteness is high, and the whiteness is preferably 200 to 300 nm because of the visible light scattering characteristics.

As a method for producing such titanium dioxide, a sulfuric acid method, a chlorine method, or the like is used, but it is not particularly limited. However, since titanium dioxide has a high specific gravity and tends to settle, it is desirable to select a particle size based on sedimentation and whiteness.

The surface treatment of the titanium dioxide particles is not particularly limited, but the resin-coated one is preferably treated with alumina on the surface because the resin component on the surface may be decomposed due to the high photocatalytic activity of titanium dioxide. The composition is preferable from the viewpoint of suppressing the catalyst activity.

These titanium dioxides are Ishihara Sangyo Co., Ltd., Sakai Chemical Industry Co., Ltd., Teika Co., Ltd., Titanium Industry Co., Ltd., Fuji Titanium Industry Co., Ltd., Furukawa Chemicals Co., Ltd. Available from Millennium Inorganic Chemicals, Inc.

<Colorant>
The ink of the present invention is mainly white, but it is also possible to adjust the color by adding other coloring components.
The coloring material to be used can be both a pigment and a dye, but it is preferable to use a pigment from the viewpoint of light fading.

As the pigment, an organic pigment or an inorganic pigment can be used. Moreover, although it may contain a dye simultaneously for the purpose of color tone adjustment, it can be used within a range in which the weather resistance is not deteriorated.

Examples of the inorganic pigment include iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, chrome yellow, titanium yellow, and carbon black. Among these, carbon black is particularly preferable.

Examples of the organic pigment include azo pigments, polycyclic pigments, dye chelates, nitro pigments, nitroso pigments, and aniline black.
Among these, azo pigments and polycyclic pigments are more preferable.

In addition, as dyes used simultaneously with pigments or alone, acid dyes, food dyes, direct dyes, basic dyes, reactive dyes, disperse dyes, and the like can be used. From the above aspect, acid dyes and food dyes are preferred.

The pigment that can be used needs to have a self-dispersibility by modifying the pigment surface so that it can be dispersed in water. In a preferred form, the surface of the pigment is modified so that at least one hydrophilic group is bonded directly or via another atomic group. For this purpose, a specific functional group (a functional group such as a sulfone group or a carboxyl group) is chemically bonded to the surface of the pigment, or wet oxidation is performed using hypohalous acid and / or a salt thereof. A method such as processing is used.

In addition, the ink using this self-dispersing pigment has excellent redispersibility after drying, so printing is paused for a long period of time, and even when ink near the nozzles of the inkjet head evaporates, it does not clog easily. Good printing can be easily performed with a simple cleaning operation.

In addition, this self-dispersing pigment has a particularly large synergistic effect when combined with a surfactant and a penetrating agent, which will be described later, and it is possible to obtain a more reliable and high-quality image.

In addition to the self-dispersing pigment, it is also possible to use a polymer emulsion in which a pigment is contained in polymer fine particles.
The polymer emulsion containing a pigment is one in which a pigment is encapsulated in polymer fine particles and / or a pigment adsorbed on the surface of the polymer fine particles. In the polymer emulsion, it is not necessary that all the pigments are encapsulated and / or adsorbed, and the pigments may be dispersed in the emulsion as long as the effects of the present invention are not impaired.

Examples of the polymer that forms the polymer emulsion include vinyl polymers, polyester polymers, and polyurethane polymers. Particularly preferred polymers are vinyl polymers and polyester polymers, such as those disclosed in JP-A Nos. 2000-53897 and 2001-139849.

Another form of the colorant is a pigment dispersion in which a pigment is dispersed by a pigment dispersant and a polymer dispersion stabilizer.

Examples of the polymer dispersion stabilizer include an α-olefin-maleic anhydride copolymer, a styrene- (meth) acrylic copolymer, a water-soluble polyurethane resin, and a water-soluble polyester resin.

As the pigment dispersant, a nonionic surfactant having an HLB value of 10 to 20 is suitable.
Examples of the nonionic surfactant having an HLB value of 10 to 20 include polyoxyethylene alkyl ether, polyoxyalkylene alkyl ether, polyoxyethylene polycyclic phenyl ether, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene Examples include ethylene alkyl phenyl ether, polyoxyethylene alkyl amine, polyoxyethylene alkyl amide, and acetylene glycol.
Among these, polyoxyethylene lauryl ether, polyoxyethylene-β-naphthyl ether, polyoxyethylene sorbitan monooleate, and polyoxyethylene styrene phenyl ether are particularly preferable.

There is no restriction | limiting in particular as a color of the said colorant, According to the objective, it can select suitably, For example, the colorant for black, the colorant for color, etc. are mentioned.
These may be used individually by 1 type and may use 2 or more types together.
Such a colorant is preferably added as necessary for the toning of the ink, and the color becomes transparent without being affected by the hiding power of white pigments such as hollow particles and titanium oxide.

<Addition of colorant>
The amount of the colorant added to the ink including the white pigment is preferably about 1 to 20% by mass, and more preferably 5 to 15% by mass for providing concealment.
When the content is 5% by mass or more, the image concealing property is good and the ink can be developed without losing the color of the recording medium. When the content exceeds 20% by mass, the ink is increased in viscosity and discharged. It may be worse, and is not preferable economically.

The average particle diameter (D50) of the colorant in the ink including the white pigment is preferably 300 nm to 1 μm or less. When the thickness exceeds 1 μm, the ejection stability is drastically reduced, and nozzle clogging and ink bending are likely to occur.
Further, when the average particle diameter (D50) is 500 nm or less, the ejection stability is improved and the dot landing position is also improved.

<Resin solid particles>
The resin solid particles have excellent film-forming properties (image formability), high water repellency, high water resistance, and high weather resistance, and have high water resistance and high image density (high color development). Useful for.
The solid particles in the present invention (hereinafter sometimes referred to as non-hollow particles) are particles in which the central portion of the particles is also formed of a solid, but it is sufficient that the central portion is formed of a solid. It does not mean only the real thing.

Examples of the resin solid particles include condensation-type synthetic resins, addition-type synthetic resins, and natural polymer compounds.

Examples of the condensed synthetic resin include polyester resin, polyurethane resin, polyepoxy resin, polyamide resin, polyether resin, poly (meth) acrylic resin, acrylic-silicone resin, and fluorine-based resin.
Examples of the addition type synthetic resin include polyolefin resins, polystyrene resins, polyvinyl alcohol resins, polyvinyl ester resins, polyacrylic acid resins, unsaturated carboxylic acid resins, and the like.
Examples of the natural polymer compound include celluloses, rosins, and natural rubber.
These may be used individually by 1 type and may use 2 or more types together.
Among these, polyurethane resin solid particles, acrylic-silicone resin solid particles, and fluororesin solid particles are particularly preferable.

Such resin solid particles may be used as a homopolymer, or may be used as a composite resin by being used as a copolymer. Any of a single-phase structure type, a core-shell type, and a power feed type emulsion may be used. Can also be used.

When using the ink of the present invention for outdoor applications such as posters and billboards, it is preferable to be able to form a coating film excellent in long-term weather resistance, and polyurethane resin particles are preferable from the viewpoint of coating film strength, and further, water resistance and heat resistance. A polycarbonate-based urethane resin having excellent properties, wear resistance, and weather resistance is preferable.

From the viewpoint of improving weather resistance, the isocyanate compound used in the polyurethane is preferably an aliphatic or alicyclic diisocyanate, and more preferably at least one alicyclic diisocyanate.
When the polycarbonate-based urethane resin particles have a structure derived from alicyclic diisocyanate, the scratch resistance and ethanol resistance are further improved.
As the alicyclic diisocyanate, isophorone diisocyanate and dicyclohexylmethane diisocyanate are particularly preferable.

Moreover, 60 mass% or more in all the isocyanate compounds is preferable for the ratio of alicyclic diisocyanate.

In the ink of the present invention, the polycarbonate-based urethane resin solid particles are added in the form of a resin emulsion dispersed in an aqueous medium.
The resin solid content in the resin emulsion is preferably 20% by mass or more. If the weight is 20% or more, there will be no problem in the formulation design when making an ink.

The volume average particle diameter of the urethane resin solid particles is preferably in the range of 10 to 350 nm from the viewpoints of liquid storage stability and ejection stability when converted into ink.

In addition, when the urethane resin solid particles are dispersed in an aqueous medium, a forced emulsification type resin emulsion using a dispersant may be used.
However, since a dispersant may remain in the coating film and lower the strength, a so-called self-emulsifying resin emulsion having an anionic group in the molecular structure is preferable.
In that case, it is preferable to have an anionic group in a ratio that the acid value is 20 to 100 in order to impart excellent scratch resistance and chemical resistance.
Such urethane resin particles can be obtained by a conventionally known production method.

Moreover, since the polycarbonate-type urethane resin has high heat resistance, by using the polycarbonate-type urethane resin solid particles, the residual solvent can be reduced and the adhesiveness can be improved by heat drying after printing.

The minimum film-forming temperature of the polycarbonate-based urethane resin solid particles is not necessarily room temperature or lower. However, in the case of performing heat drying, it is desirable that the temperature is at least the temperature to be heated after printing. It is desirable that the temperature be 5 ° C. or more lower.

For example, when the heating temperature is 60 ° C, the minimum film-forming temperature of the resin is preferably in the range of 0 ° C to 55 ° C, more preferably in the range of 25 ° C to 55 ° C. In general, the lower the film-forming temperature is, the better the film-forming property is. However, if the minimum film-forming temperature is too low, the glass transition point of the resin is lowered and sufficient film strength cannot be obtained.

In addition, the polycarbonate urethane resin solid particles used in the present invention preferably have a surface hardness of 100 N / mm ² or more when a coating film is formed. When this condition is satisfied, the ink forms a tough coating film, and stronger scratch resistance is obtained.

The addition amount of the polycarbonate urethane resin solid particles in the ink is preferably 0.5 to 10% by mass in terms of solid content, more preferably 1 to 8% by mass, and further preferably 3 to 8% by mass. is there.
When the addition amount is 0.5% by mass or more, a sufficient coating is formed on the pigment, and the required image fastness can be obtained. Further, when the addition amount is 10% by mass or less, there is no case where the viscosity becomes too high and the discharge becomes difficult.

<Water-soluble organic solvent>
As the water-soluble organic solvent, it is necessary not to include a water-soluble organic solvent having a boiling point of 250 ° C. or higher in order to ensure the drying property.

The ink of the present invention becomes a gas through the drying process inside the inorganic hollow particles and resin hollow particles as described above, and causes light scattering by expressing a difference in refractive index from the enclosing solid, Whiteness improves by appearing white.
Therefore, it is necessary for the water-soluble organic solvent to volatilize before the resin solid particles or the like are formed into a film, and the drying property of the water-soluble organic solvent is low. Water-soluble organic solvent remains in the interior of the glass, and the whiteness decreases.

As the water-soluble organic solvent, if the boiling point is 250 ° C. or lower, a conventionally known water-soluble organic solvent can be used as necessary for the purpose of controlling the physical properties of the ink, preventing drying, and improving the dissolution stability. .

Examples of the water-soluble organic solvent include polyhydric alcohols, polyhydric alcohol alkyl ethers, polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, sulfur-containing compounds, propylene carbonate, and carbonic acid. Ethylene is mentioned.

As for the water-soluble organic solvent used by this invention, it is preferable that 50 mass% or more is a diol compound of polyhydric alcohols. In the present invention, the diol compound refers to a compound having two OH groups in the chemical structural formula.
These diol compounds have higher water retention than compounds that do not contain OH groups or compounds that contain only one OH group, and greatly contribute to ink ejection reliability.
On the other hand, in the case of a compound containing 3 or more OH groups, the intermolecular force becomes too strong, so many of the boiling points are extremely high, and the drying property is greatly impaired.
Therefore, in the ink of the present invention, it is important to balance moisture retention and drying properties.

Examples of the diol compound include ethylene glycol (bp 196 ° C.), propylene glycol (bp 188 ° C.), 1,2-butanediol (bp 194 ° C.), 2,3-butanediol (bp 183 ° C.), 3-methoxy-3- Methyl-1-butanol (bp 174 ° C.), 2-methyl-2,4-pentanediol (bp 198 ° C.), diethylene glycol (bp 244 ° C.), triethylene glycol (bp 287 ° C.), dipropylene glycol (bp 230 ° C.), 1,3 Propanediol (bp 214 ° C.), 1,3-butanediol (bp 203 ° C.), 1,4-butanediol (bp 230 ° C.), 2,2-dimethyl-1,3-propanediol (bp 208 ° C.), 2-methyl -1,3-propanediol (bp 213 ° C.), 1,2-penta Diol (bp 206 ° C), 2,4-pentanediol (bp201 ° C), 1,5-pentanediol (bp242 ° C), 1,6-hexanediol (bp250 ° C), 2-ethyl-1,3-hexanediol ( bp 243 ° C), 1,2-hexanediol (bp224 ° C), 2,5-hexanediol (bp217 ° C) and the like.

Moreover, 50 mass% or more of the water-soluble organic solvent used in the present invention preferably has a boiling point of 200 ° C. or less, and more preferably 55 mass% or more and less than 70 mass%.
When the solvent having a boiling point of 200 ° C. or lower is 50% by mass or more of the total water-soluble organic solvent, drying from the image after ejection is promoted, and fixing and white stability are improved. Further, when the content is 55% by mass or more, drying proceeds at a lower temperature, so that the heating temperature of the recording medium can be lowered.
In addition, when the amount is less than 70% by mass, drying of the nozzle surface of the head can be suppressed, and the amount of ink used for maintenance can be reduced.

Examples of water-soluble organic solvents having a boiling point of 200 ° C. or lower include ethylene glycol (bp 196 ° C.), propylene glycol (bp 188 ° C.), 1,2-butanediol (bp 194 ° C.), and 2,3-butanediol (bp 183 ° C.). 3-methoxy-3-methyl-1-butanol (bp 174 ° C.), 2-methyl-2,4-pentanediol (bp 198 ° C.), dipropylene glycol monomethyl ether (bp 190 ° C.), propylene glycol n-butyl ether (bp 171 ° C.) Propylene glycol-t-butyl ether (bp 153 ° C.), diethylene glycol methyl ether (bp 194 ° C.), ethylene glycol-n-propyl ether (bp 150 ° C.), ethylene glycol-n-butyl ether (bp 171 ° C.) and the like. These may be used individually by 1 type and may use 2 or more types together.

In addition, a water-soluble organic solvent having a boiling point of 200 ° C. or lower is obtained because it has good compatibility with many water-dispersible resins, in particular, good compatibility with polycarbonate-based urethane resin particles, and more excellent film-forming properties. It is preferable to use at least one of 3-methoxy-3-methyl-1-butanol and 2,3-butanediol. This improves the gloss of the coating film.

The content of the water-soluble organic solvent in the ink is preferably about 20 to 50% by mass.
It is preferable to use a water-soluble organic solvent in an amount of 20% by mass or more of the entire ink because it is excellent in securing ejection stability and preventing waste ink sticking in a maintenance device of the ink ejection apparatus.
If the amount added is less than 50% by mass, the liquidity of the ink will not be extremely organic, the affinity of the hollow particles and resin particles with water will be maintained, and the dispersion stability of the dispersed components in the ink will be maintained. A discharge failure can be prevented because the increase in the particle size and the adsorption to the flow path in the head are suppressed.

<Surfactant>
As the surfactant, those having a low surface tension, a high permeability and a high leveling property can be preferably used without impairing the dispersion stability depending on the kind of the colorant or the combination of the water-soluble organic solvent.
Such surfactants are selected from fluorosurfactants, silicone surfactants, acetylene glycol surfactants, acetylene alcohol surfactants, anionic surfactants, and nonionic surfactants. At least one of these is preferred.
Among these, silicone surfactants, fluorine surfactants, acetylene glycol surfactants, and acetylene alcohol surfactants are particularly preferable.
These may be used alone or in combination of two or more.

As the fluorine-based surfactant, a surfactant having 2 to 16 carbon atoms substituted with fluorine is preferable, and a surfactant having 4 to 16 carbon atoms substituted with fluorine is more preferable.
If the fluorine-substituted carbon number is less than 2, the effect of fluorine may not be obtained, and if it exceeds 16, problems such as ink storage stability may occur.

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 a side chain. And polyoxyalkylene ether polymer compound.
Among these, a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain is particularly preferable because of its low foaming property.

Further, it is preferably a fluorine-based surfactant represented by the following general formula (III) or (IV).

ただし、前記一般式（ＩＶ）中、ｎは２〜６の整数であり、ａは１５〜５０の整数であり、Ｙ’は−Ｃ_ｂＨ_２ｂ＋１（ｂは１１〜１９の整数である）又は−ＣＨ_２ＣＨ（ＯＨ）ＣＨ_２−Ｃ_ｄＦ_２ｄ＋１（ｄは２〜６の整数である）を表す。

In the general formula (IV), n is an integer from 2 to 6, a is an integer from 15 to 50, Y 'is _-C b _{H 2b +} 1 (b is an integer of 11 to 19) or represents a _{-CH 2 CH (OH) CH 2} -C d F 2d + 1 (d is an integer from 2 to 6).

As said fluorosurfactant, what was synthesize | combined suitably may be used and a commercial item may be used.
Examples of the commercially available products include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, and S-145 (all manufactured by Asahi Glass Co., Ltd.); Fullrad FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (all manufactured by Sumitomo 3M Limited); Megafac F-470, F -1405, F-474 (all manufactured by DIC Corporation); Capstone FS-10, FS-22, FS-30, FS-31, FS-3100, FS-34, FS-35, FS -50,
FS-51, FS-60, FS-61, FS-63, FS-64, FS-65, FS-66, FS-81, FS-82, FS-83 (all manufactured by DuPont); FT- 110, FT-250, FT-251, FT-400S, FT-150, FT-400SW (all manufactured by Neos Co., Ltd.), Polyfox PF-151N (manufactured by Omninova), and the like. , Capstone FS-31, FS-3100, FS-34 manufactured by DuPont, and Polyfox PF-151N manufactured by Omninova are particularly preferable from the standpoint of significantly improving good print quality, particularly color development and leveling. .

There is no restriction | limiting in particular as said silicone type surfactant, Although it can select suitably according to the objective, What does not decompose | disassemble at high pH is preferable.
For example, side chain modified polydimethylsiloxane, both terminal modified polydimethylsiloxane, one terminal modified polydimethylsiloxane, side chain both terminal modified polydimethylsiloxane, etc. are mentioned, and polyoxyethylene group, polyoxyethylene polyoxypropylene as modified groups A polyether-modified silicone surfactant having a group is particularly preferred because it exhibits good properties as an aqueous surfactant.

There is no restriction | limiting in particular as said polyether modified silicone type surfactant, According to the objective, it can select suitably, For example, the polyalkylene oxide structure represented by the following general formula (V) is Si of dimethylpolysiloxane. Examples include compounds introduced into partial side chains.

ただし、一般式（Ｖ）中、ｍ、ｎは１以上の整数を表し、Ｘは、−Ｒ（Ｃ_２Ｈ_４Ｏ）_ａ（Ｃ_３Ｈ_６Ｏ）_ｂＲ’（ａ及びｂは、１以上３０以下の整数、Ｒ及びＲ’は炭素数１〜４のアルキル基、炭素数１〜４のアルキレン基を表す）を表わす。

However, in the general formula (V), m, n represents an integer of 1 or more, X _{is, -R (C 2 H 4 O} ) a (C 3 H 6 O) b R '(a and b, 1 Integers of 30 or less, R and R ′ represent an alkyl group having 1 to 4 carbon atoms and an alkylene group having 1 to 4 carbon atoms.

As the polyether-modified silicone surfactant, an appropriately synthesized one or a commercially available product may be used.
As said commercial item, it can obtain easily from Big Chemie Co., Ltd., Shin-Etsu Silicone Co., Ltd., Toray Dow Corning Silicone Co., Ltd. etc., for example.
As said commercial item, KF-618, KF-642, KF-643 (all are Shin-Etsu Chemical Co., Ltd. product) etc. are mentioned, for example.

  The acetylene glycol surfactant or acetylene alcohol surfactant is preferably a compound represented by the following general formula (VI) or the following general formula (VII).

ただし、前記一般式（ＶＩ）中、ｍ又はｎは、１以上２５以下の整数を表す。

However, in said general formula (VI), m or n represents the integer of 1-25.

ただし、前記一般式（ＶＩＩ）中、Ｒ１及びＲ２は、炭素数１〜８のアルキル基を表す。

However, in said general formula (VII), R1 and R2 represent a C1-C8 alkyl group.

Examples of the surfactant represented by the general formula (VII) include those represented by the following structural formula (VIII).

  As the acetylene glycol surfactant or acetylene alcohol surfactant, commercially available products can be used. Examples of the commercially available products include Dynol 604 and Dynol 607 (manufactured by Air Products and Chemicals); Nol 104, Surfinol 420, Surfinol 440, Surfinol SE (manufactured by Nissin Chemical Industry Co., Ltd.); Orphin E1004, Orphin E1010, Orphin EXP. 4001, Olfine EXP. 4200, Olfine EXP. 4051F, Olfine EXP. 4123 (manufactured by Nissin Chemical Industry Co., Ltd.).

Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, laurate, polyoxyethylene alkyl ether sulfate salt, and the like.

Examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxypropylene polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene alkylphenyl ether, and polyoxyethylene alkyl. Examples include amines and polyoxyethylene alkylamides.

The content of the surfactant in the inkjet ink is preferably 0.01% by mass to 3.0% by mass, and more preferably 0.5% by mass to 2.0% by mass.
When the content is 0.01% by mass or more, the effect of adding the surfactant appears in the ink physical properties. In addition, the nozzle surface of the inkjet head holds the interface between the ink and the nozzle surface in order to maintain the meniscus of the nozzle hole, but keeps the meniscus uniformly up to a surfactant concentration of 3.0% by mass. be able to.

<Other ingredients>
In addition to the above-described components, the ink of the present invention may contain other components such as an antiseptic / antifungal agent, a rust inhibitor, and a pH adjuster as necessary.

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.

As the pH adjuster, any substance can be used as long as it can adjust the pH to a desired value without adversely affecting the ink to be prepared. Examples thereof include hydroxides of alkali metal elements such as lithium hydroxide, sodium hydroxide and potassium hydroxide, carbonates of alkali metals such as lithium carbonate, sodium carbonate and potassium carbonate, quaternary ammonium hydroxides and the like. Examples include amines such as diethanolamine and triethanolamine, ammonium hydroxide, and quaternary phosphonium hydroxide.

The ink of the present invention is prepared by dissolving the above-described constituents in an aqueous medium and further stirring and mixing as necessary. The stirring and mixing can be performed, for example, with a stirrer using a normal stirring blade, a magnetic stirrer, a static mixer using a liquid flow, an ultrasonic homomixer, a high-speed mixer-type disperser, or the like.

<Ink cartridge>
The ink cartridge used in the present invention contains the ink-jet ink of the present invention in a container, and further includes other members and the like appropriately selected as necessary.
The container is not particularly limited, and its shape, structure, size, material and the like can be appropriately selected according to the purpose. For example, at least an ink bag formed of an aluminum laminate film, a resin film, or the like Preferred examples include those possessed.

Next, the ink cartridge will be described with reference to FIGS.
Here, FIG. 1 is a schematic view showing the ink cartridge, and FIG. 2 is a schematic view showing a modification of the ink cartridge of FIG.

As shown in FIG. 1, in the ink cartridge 201, the ink bag 241 is filled with the ink jet ink of the present invention from the ink inlet 242 and exhausted, and then the ink inlet 242 is closed by fusion.
In use, a needle of an ink jet recording apparatus 101 (to be described later with reference to FIG. 3) is stabbed into an ink discharge port 243 made of a rubber member and supplied to the ink jet recording apparatus 101.

The ink bag 241 is formed of a packaging member such as an aluminum laminate film having low air permeability.
As shown in FIG. 2, the ink bag 241 is usually housed in a plastic cartridge case 244 and is detachably mounted on various ink jet recording apparatuses.

The ink cartridge 201 contains the ink-jet ink (ink set) of the present invention and can be used by being detachably mounted on various ink-jet recording apparatuses, and can be detachably mounted on the ink-jet recording apparatus of the present invention described later. It is particularly preferable to install and use.

<Inkjet recording method and inkjet recording apparatus>
The inkjet recording method of the present invention includes at least an ink flying process, and further includes other processes appropriately selected as necessary, for example, a stimulus generation process, a control process, a heat drying process, and the like.

The ink jet recording apparatus of the present invention includes at least ink flying means, and further includes other means appropriately selected as necessary, for example, stimulus generation means, control means, heat drying means, and the like.

The ink jet recording method of the present invention can be preferably carried out by the ink jet recording apparatus of the present invention, and the ink flying step can be suitably carried out by the ink flying means.
Moreover, the said other process can be suitably performed by the said other means.

-Ink flying process and ink flying means-
The ink flying step is a step of forming an image on a recording medium by applying a stimulus (energy) to the ink jet ink of the present invention and causing the ink jet ink to fly.
The ink flying means is means for applying an stimulus (energy) to the ink jet ink of the present invention and causing the ink jet ink to fly to form an image on a recording medium.
The ink flying means is not particularly limited, and examples thereof include various nozzles for ejecting ink.

The stimulus (energy) 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. For example, heat (temperature), pressure, vibration And light.
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, for example, 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, and a shape memory alloy that uses a metal phase change caused by a temperature change Examples thereof include an actuator and an electrostatic actuator using an electrostatic force.

The size of the droplets of the inkjet ink to be ejected is preferably 3 × 10 ¹⁵ m ³ to 40 × 10 ¹⁵ m ³ ( ³ pL to 40 pL), for example.

In addition, it is preferable that the ejection speed of the inkjet ink droplets is 5 m / s to 20 m / s.

The drive frequency for ejecting and ejecting ink-jet ink droplets is preferably 1 kHz or more, and the resolution is preferably 60 dpi or more, and more preferably 150 dpi or more.

In the ink jet recording method, a recording medium on which an image is formed by flying the ink jet ink can be provided with a heat drying step as necessary.

In the heating and drying step, the printing paper can be dried with an infrared drying device, a microwave drying device, a roll heater, a drum heater or hot air. By accelerating the drying and fixing during printing, it is possible to accelerate the drying immediately after the ink adheres and suppress the movement of the liquid.
Thereby, beading and bleeding can be suppressed, and the printability and image quality on the recording medium can be improved. Further, by promoting drying, the resin component in the ink component can easily form a film, and the fixability immediately after printing can be improved.

In order to promote dry fixing during printing in this way, it is necessary to heat the media before printing or to heat the printing during printing.
It is preferable that the heated medium is 40 to 100 ° C. under the ink discharge head. Heating in the vicinity of the ink ejection head dries the meniscus of the head nozzle portion and deteriorates ejection performance. Therefore, 40-60 degreeC under a head is more preferable. Such heating can be performed in the heat drying step.
In these heating steps, it is preferable to change the heating state according to the printing conditions, and it is possible to use a capacitor in combination to cover the power used for rapid heating.

The heating temperature can be changed according to the type and amount of the water-soluble organic solvent contained in the ink and the minimum film-forming temperature of the water-dispersed resin to be added, and further changed according to the type of recording medium to be printed. can do.

The heating temperature is preferably high from the viewpoints of drying property and film forming temperature, but if the heating temperature is too high, the recording medium to be printed is damaged. If the heater is heated too much during printing, the ink head may be heated and non-ejection may occur, which is not preferable.
Therefore, it is preferable to print in the range of 40 to 70 ° C. on the recording surface side of the recording medium because a good image without color bleeding or dot fusion can be formed.

In addition, a fixing step may be provided in which heat is fixed to 70 ° C. to 120 ° C. by heating means as drying after printing. By providing this fixing step, the gloss and fixability of the ink recorded matter are improved.

As the heat fixing means, a roller having a heated mirror surface, a drum heater or the like is preferably used, and the mirror surface portion (smooth portion) of the roll heater or drum heater can be brought into contact with the image forming surface.

Regarding the heating temperature, a fixing roller heated to 70 ° C. to 100 ° C. is preferable in consideration of the heat resistance of the media, image quality, safety, and economy.
The control means is not particularly limited as long as the movement of each means can be controlled, and can be appropriately selected according to the purpose. Examples thereof include devices such as sequencers and computers.

<Detailed description of device>
Here, one mode for carrying out the ink jet recording method of the present invention using a serial type ink jet recording apparatus will be described with reference to the drawings.

An ink jet recording apparatus 101 shown in FIG. 3 has an ink jet recording apparatus main body, a paper feed tray 102 for loading a recording medium (paper) into the apparatus main body, and an ink jet recording apparatus main body 101 to form (record) an image. ) And a paper discharge tray 103 for stocking the printed paper, 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 that can be opened and closed for attaching and detaching the ink cartridge 201.

In the main body of the ink jet recording apparatus 101, as shown in FIGS. 3 and 4, a carriage 133 is formed by a guide rod 131 and a sub guide rod 132, which are guide members horizontally mounted on left and right side plates (not shown). It is slidably held in the main scanning direction, and is moved and scanned in the direction indicated by the arrow in FIG.

The carriage 133 includes a recording head composed of five inkjet recording heads that eject inkjet ink droplets of each color of white (W), yellow (Y), cyan (C), magenta (M), and black (Bk). A plurality of ink ejection openings 134 are arranged in a direction crossing the main scanning direction, and the ink droplet ejection direction is directed 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 using a change, an electrostatic actuator using an electrostatic force, or the like provided as energy generating means for discharging ink can be used.

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 and supplemented with the ink jet ink of the present invention from the ink cartridge 201 of the present invention loaded in the ink cartridge loading section 104 via an ink jet ink supply tube (not shown).

On the other hand, as a paper feeding unit for feeding the paper 142 stacked on the paper stacking unit (pressure plate) 141 of the paper feeding tray 102, a paper feeding roller 143 that separates and feeds the paper 142 from the paper stacking unit 141 one by one. (Half-moon roller) and a separation pad made of a material having a large friction coefficient are provided opposite to the sheet feeding roller 143, and this separation pad is biased toward the sheet feeding roller 143 side.

As a conveyance unit for conveying the sheet 142 fed from the sheet feeding unit below the recording head 134, the sheet 142 is sent to the sheet feeding roller 157 and the counter roller 154 through the guide roller 152, and below the recording head 134. Transport to. The paper 142 is conveyed while being held by the paper feed roller 157 and the counter roller 154, printed by the recording head 134, and the printed paper 142 is held by the paper discharge roller 172 and the spur roller 173 and is discharged from the printing unit. The

A guide member 161 is arranged corresponding to the printing area by the recording head 134, and a printing heater 184 is arranged on the back surface of the guide member 161. The heat from the heater 184 during printing warms the guide member 161 and heats the paper 142 in the printing area.

The sheet 142 discharged from the printing unit is dried by the warm air heater 181 and the infrared heater 182 on the printing surface and the back surface heater 183 on the back surface to dry the sheet.
In order to prevent the paper 142 from contacting the warm air heater 181 and the infrared heater 182 and to make the paper 142 come into close contact with the back heater, a plurality of spur rollers 171 are provided, and the paper is conveyed to the paper discharge tray 103.

For printing, the recording head 134 is driven in accordance with the image signal while moving the carriage 133 with respect to the paper 142 conveyed under the recording head 134, thereby ejecting ink droplets onto the stopped paper 142. Minutes are recorded, and after the sheet 142 is conveyed by a predetermined amount, the next line is recorded.

Upon receiving a recording end signal or a signal that the trailing edge of the sheet 142 has reached the recording area, the recording operation is terminated and the sheet 142 is discharged onto the discharge tray 103.

When a near-end of the ink jet ink in the sub tank 135 is detected, a required amount of ink jet ink is supplied from the ink cartridge 201 to the sub tank 135.

In this ink jet recording apparatus, when the ink for ink jet in the ink cartridge 201 is used up, the casing of the ink cartridge 201 can be disassembled and only the ink bag 241 inside can be replaced.

In addition, although it demonstrated in the example applied to the serial type (shuttle type) inkjet recording device which a carriage scans, it can apply similarly to the line type inkjet recording device provided with the line type head.

In the case of a line type ink jet recording apparatus, the same effect as the multi pass printing of the serial type ink jet recording apparatus can be obtained by arranging a plurality of heads of the same color in the print path, instead of being able to print by multi pass, Instead of lowering the surface temperature of the recording medium according to the increase in the number of image print scans, the image temperature of the printed matter can be improved by lowering the surface temperature as the number of line heads of the same color increases.

The ink jet recording apparatus and the ink jet recording method of the present invention can be applied to various types of recording by the ink jet recording method, and are particularly suitable for, for example, an ink jet recording printer, a facsimile apparatus, a copying apparatus, and a printer / fax / copier multifunction machine. Can be applied.

<Inkjet recording>
The inkjet recorded matter of the present invention has an image formed on the recording medium using the ink of the present invention.
The recording medium is not particularly limited, and plain paper, glossy paper, special paper, cloth, and the like can be used. The ink of the present invention is particularly good when applied to a non-ink-absorbing recording medium. An image with color development can be provided.
In the present invention, the non-ink-absorbing recording medium is a non-porous recording medium and has no ink absorbing ability.
Examples of the non-ink-absorbing recording medium include transparent or colored films and ceramics.

The film is made of a plastic material such as a polyvinyl chloride film, a polyethylene terephthalate (PET) film, a polycarbonate film, an acrylic film, a polypropylene film, a polyimide film, or a polystyrene film.

In addition, even when the recording medium is colored by printing before the color ink at the time of color printing, the color of the recording medium can be made to be white, and the color development of the color ink can be improved. it can.
Typical examples of the colored recording medium include colored paper, the film, fabrics, clothes, and ceramics.

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

(1) <Preparation of inorganic hollow particle dispersion>
Dissolve 10.0 g of DISPERBYK-2008 (acrylic copolymer manufactured by BYK, active ingredient 60%) in 294.0 g of high-purity water in a beaker and stir with an Excel auto homogenizer manufactured by Nippon Seiki Seisakusho at 5000 rpm for 30 minutes. Silinax: Nippon Steel & Co., Ltd. hollow silica (primary particle size 80-130 nm, silica film thickness 5-15 nm) 50.0 g was added in 10 portions, mixed and dispersed until no lumps, gradually rotating The mixture was stirred for 30 minutes at 10,000 rpm.
The obtained pigment dispersion was treated with an ultrasonic homogenizer US-300T (Chip φ26) manufactured by Nippon Seiki Seisakusho for 1 hour while cooling with water, and filtered with a 5 μm membrane filter (cellulose acetate membrane). An inorganic hollow particle dispersion having 14.1% by mass of hollow particles was obtained.

(2) <Preparation of organic white pigment dispersion>
In a beaker, 5 g of polyoxyethylene styrenated phenyl ether (Neugen EA-177: manufactured by Daiichi Kogyo Seiyaku Co., Ltd., HLB 15.6, solid content 100% by mass) was dissolved in 200.0 g of high-purity water, and organic white pigment particles (Shigenox OWP) : Manufactured by Nippon Seiki Seisakusho Co., Ltd., with stirring at 5000 rpm for 30 minutes, dispersed to a lump-free state, gradually increasing the number of revolutions and increasing to 30 at 10,000 rpm. Stirring was performed for a minute.
The obtained organic white pigment particle dispersion was treated with an ultrasonic homogenizer US-300T (Chip φ26) manufactured by Nippon Seiki Seisakusho for 1 hour while cooling with water, and the obtained organic white pigment particle dispersion was treated with Shinmaru Enterprises. Advanced nanotechnology nano maker manufactured by DYNO-Mil multi-lab type manufactured by DYNO-Mil, using zirconia beads with a particle size of 2 mm as media particles, with a bead filling rate of 70 vol%, a stirring blade peripheral speed of 8 m / s, and batch processing for 30 minutes. Was used for 20-pass dispersion treatment at a pressure of 100 MPa.
Thereafter, the mixture was filtered through a 5 μm membrane filter (cellulose acetate membrane) to obtain an organic white pigment particle dispersion having 19.6% by mass of organic white pigment particles.

(3) <Preparation of titanium dioxide pigment dispersion>
In a beaker, 37.5 g of acrylic copolymer (DISPERBYK-2008: manufactured by BYK, active mass 60% by mass) is dissolved in 100.0 g of high-purity water, and titanium oxide (JR-600A: manufactured by Teika (primary particle diameter 250 nm, surface treatment: Al )) 30.0 g was added, and the mixture was stirred with an excel auto homogenizer manufactured by Nippon Seiki Seisakusho at 5000 rpm for 30 minutes, dispersed to a state free of lumps, gradually increased in rotational speed, and stirred at 10,000 rpm for 30 minutes.
The obtained titanium dioxide pigment dispersion was treated with an ultrasonic homogenizer US-300T (Chip φ26) manufactured by Nippon Seiki Seisakusho for 1 hour with water cooling and filtered with a 5 μm membrane filter (cellulose acetate membrane). The mixture was filtered through a 5 μm membrane filter (cellulose acetate membrane) to obtain a titanium dioxide pigment dispersion having a titanium dioxide pigment content of 17.9% by mass.

(4) <Preparation of urethane resin emulsion>
In a reaction vessel into which a stirrer, a reflux condenser and a thermometer are inserted, 1500 g of polycarbonate diol (reaction product of 1,6-hexanediol and dimethyl carbonate), 2,2-dimethylolpropionic acid (hereinafter sometimes referred to as DMPA) 220 g and 1347 g of N-methylpyrrolidone (hereinafter sometimes referred to as NMP) were charged in a nitrogen stream and heated to 60 ° C. to dissolve DMPA.
Next, 1,445 g of 4,4′-dicyclohexylmethane diisocyanate and 2.6 g of dibutyltin dilaurate (catalyst) were added and heated to 90 ° C. to carry out a urethanization reaction over 5 hours to obtain an isocyanate-terminated urethane prepolymer. .
Next, the reaction mixture was cooled to 80 ° C., 4340 g was extracted from the mixture in which 149 g of triethylamine was added and mixed, and added to a mixed solution of 5400 g of water and 15 g of triethylamine with vigorous stirring.
Next, 1500 g of ice was added, 626 g of 35% by mass of 2-methyl-1,5-pentanediamine aqueous solution was added to carry out chain extension reaction, and the solvent was distilled off so that the solid content concentration became 30% by mass. A urethane resin emulsion was obtained.

This emulsion was applied onto a slide glass so as to have a film thickness of 10 μm, and dried at 100 ° C. for 30 minutes to form a resin film.
Then, using a micro surface hardness tester (FISCHERSCOPE HM2000, manufactured by Fischer), the Martens hardness when the Vickers indenter was pushed in with a load of 9.8 mN was measured, and the result was 120 N / mm ² .

≪Ink adjustment≫
[Example 1]
2,3-butanediol 10% by mass, 3-methoxy-3-methyl-1-butanol 8% by mass, 1,3-propanediol 10% by mass, 2-ethyl-1,3-hexanediol 3% by mass, interface 0.1% by mass of activator, 0.5% by mass of antifoaming agent, 0.05% by mass of antibacterial agent, and 1.65% by mass of high-purity water were added to a beaker and stirred for 15 minutes with a stirrer to mix uniformly .
10 mass% of the prepared urethane resin emulsion (resin solid particles) was added to this mixed solution and stirred for 15 minutes, and then 56.7 mass% of the inorganic hollow particle dispersion was added and stirred for 30 minutes. Thereafter, the resultant was filtered under pressure through a 5.0 μ cellulose acetate membrane filter to remove coarse particles, and an evaluation ink was obtained.

[Example 2]
Evaluation inks were produced in the same manner as in Example 1 except that the mixing ratios shown in Table 1 were used.

[Example 3]
Evaluation inks were produced in the same manner as in Example 1 except that the mixing ratios shown in Table 1 were used.

[Example 4]
Evaluation inks were produced in the same manner as in Example 1 except that the mixing ratios shown in Table 1 were used.

[Example 5]
Evaluation inks were produced in the same manner as in Example 1 except that the mixing ratios shown in Table 1 were used.

[Example 6]
Evaluation inks were produced in the same manner as in Example 1 except that the mixing ratios shown in Table 1 were used.

[Example 7]
Evaluation inks were produced in the same manner as in Example 1 except that the mixing ratios shown in Table 1 were used.

[Comparative Example 1]
Evaluation inks were produced in the same manner as in Example 1 except that the mixing ratios shown in Table 1 were used.

[Comparative Example 2]
Evaluation inks were produced in the same manner as in Example 1 except that the mixing ratios shown in Table 1 were used.

[Comparative Example 3]
Evaluation inks were produced in the same manner as in Example 1 except that the mixing ratios shown in Table 1 were used.

[Comparative Example 4]
Evaluation inks were produced in the same manner as in Example 1 except that the mixing ratios shown in Table 1 were used.

[Comparative Example 5]
Evaluation inks were produced in the same manner as in Example 1 except that the mixing ratios shown in Table 1 were used.

The materials in Table 1 are shown below.
Inorganic hollow particles: Silax, manufactured by Nippon Steel & Mining Co., Ltd. Hollow silica (primary particle diameter of 80 to 130 nm, silica film thickness of 5 to 15 nm)
Resin hollow particle dispersion: Ropaque ULTRA E: manufactured by Rohm and Haas (solid content: 30% by mass)
Organic white pigment particles: Shigenox OWP, made by Hackol Chemical
Titanium dioxide pigment: JR-600A: manufactured by Teica, titanium oxide (primary particle diameter) 250 nm, surface treatment: Al)
Surfactant: Fluorosurfactant DSN-403N Daikin Industries, Ltd. Surfactant: Polyether-modified silicone surfactant KF-353 Shin-Etsu Chemical Co., Ltd. Defoamer: Envirogem AD-01 Air Products
Antibacterial agent: Proxel GXL

≪Ink sedimentation evaluation≫
The sedimentation property of the pigment of the prepared ink was evaluated using Turbscan MA2000 (manufactured by Eihiro Seiki Co., Ltd.).
As a method, the evaluation ink was subjected to ultrasonic dispersion treatment (100 W, 40 minutes) to obtain a uniform state, and then 5.5 ml of the evaluation ink was put into a glass cell dedicated to the apparatus using a pipette.
Measurement was performed 30 minutes after the liquid level of the evaluation ink in the cell was stabilized, and this time was set as the start of sedimentation evaluation.
Then, it left still at 23 degreeC, it measured until 120 hours later, and the sedimentation property was confirmed by the deviation display on the basis of the sedimentation evaluation start. Confirmation of sedimentation was performed mainly by measuring the change in backscattered light due to the production of the supernatant by integrating the peaks (relative value mode) and evaluating the following criteria.
A: Relative change after 120 hours of evaluation is less than 5% B: Relative change after 120 hours of evaluation is 5% or more and less than 10% C: Relative change after 120 hours of evaluation is 10% or more

<Printing conditions>
Remove the exterior of the inkjet printer (Ricoh's IPSiO GXe3300), attach the rear multi-manual feeder, clean it by passing pure water through the ink supply path including the print head, and pass it thoroughly until the cleaning liquid stops coloring. Then, the cleaning solution was completely removed from the apparatus to obtain an evaluation printing apparatus.
Further, the evaluation ink was stirred for 30 minutes under a reduced pressure condition of 5 to 10 Pa to degas the gas in the evaluation ink and filled in the ink cartridge to obtain an evaluation ink cartridge.
A filling operation was performed, and it was confirmed that all nozzles were filled with evaluation ink and no abnormal image appeared. After selecting the glossy paper clean mode with the driver attached to the printer, the color matching off was set to the print mode by the user setting. In this mode, the ejection amount was adjusted by changing the driving voltage of the head so that the amount of ink adhering to the medium of the solid image was 20 g / m ² .

≪Evaluation of whiteness of printed image≫
A transparent PET film (Toyobo Ester Film E5100) fixed with double-sided tape on My Paper (Ricoh PPC plain paper) was fed from the back multi-manual feeder, with a solid image of 50 mm x 50 mm created by Microsoft Word 2003. Printing was performed on the PET film surface. After printing, the recording medium was placed in a constant temperature bath at 80 ° C. and dried for 2 hours for evaluation.
With the commercially available black paper laid under the printed PET film, the printed portion was measured for lightness (L ^* ) using a spectrocolorimetric densitometer X-Rite 939.

L ^* was evaluated according to the following criteria.
A: L ^* value is 70 or more B: L ^* value is 60 or more and less than 70 C: L ^* value is less than 60 For reference, measurement was performed with an unprinted PET film laid on black paper. The L ^* value was 23.1.

≪Whiteness stability of printed image≫
A transparent PET film (Toyobo Ester Film E5100) fixed with double-sided tape on My Paper (Ricoh PPC plain paper) was fed from the back multi-manual feeder, with a solid image of 50 mm x 50 mm created by Microsoft Word 2003. Printing was performed on the PET film surface.
After printing, the recording medium is put in a constant temperature bath at 80 ° C., and the brightness is measured for a sample dried for 15 minutes and a sample dried for 2 hours, and a difference in brightness ΔL ^* = ( _after L ^* _{2 hours} ) − (L ^* _{15 minutes later} ) was calculated and evaluated.

The lightness was measured using a spectrocolorimetric densitometer X-Rite 939 with a commercially available black paper laid under the printed PET film.

A: ΔL ^* value is less than 5 B: ΔL ^* value is 5 or more and less than 10 C: ΔL ^* value is 10 or more

≪Discharge stability evaluation≫
After printing a nozzle check pattern with a printer filled with the evaluation ink and confirming that complete ejection is possible, leave the head covered and left at a temperature of 10 ° C. and a humidity of 15% RH for 1 week, and then print the nozzle check pattern. The presence or absence of non-ejection and jet turbulence was determined by visual observation based on the following criteria.

A: No ejection, no injection disturbance
B: Some injection disturbance is recognized.
C: There is a nozzle where ejection failure is observed.
D: Non-ejection is recognized in a plurality of nozzles.

≪Scratch resistance evaluation of printed images≫
A transparent PET film (Toyobo Ester Film E5100) fixed with double-sided tape on My Paper (Ricoh PPC plain paper) was fed from the back multi-manual feeder, with a solid image of 50 mm x 50 mm created by Microsoft Word 2003. Printing was performed on the PET film surface. After printing, it was dried at 80 ° C. for 1 hour.

The solid image was rubbed with a dry cotton cloth (Kanakin No. 3) under a load of 400 g, and the rub resistance was determined according to the following criteria.

A: The image does not change even after rubbing 50 times or more.
B: Some scratches remain at the stage of rubbing 50 times, but the brightness of the image is not affected, and there is no problem in actual use.
C: Image brightness decreases during rubbing 21 to 50 times.
D: Image brightness is lowered by rubbing 20 times or less.

≪Result≫
The evaluation results are shown in Table 2.

As in Examples 1 to 7, when inorganic hollow particles are included and a water-soluble organic solvent having a boiling point of 250 ° C. or higher is not included, the whiteness of the ink is good and the whiteness is stable.
Further, as in Comparative Examples 1 and 2 and Comparative Example 5, when a water-soluble organic solvent (glycerin) having a boiling point of 250 ° C. or higher is contained, the drying property is deteriorated, the stability of whiteness is poor, and the image is scratched. It will decline. By using an organic white pigment as the color material, the whiteness stability and ejection stability are good, but the whiteness does not improve.

As in Examples 4 to 7, by adding resin hollow particles and organic white pigment particles in accordance with the inorganic hollow particles, the whiteness can be complemented and the concealability is improved.
When a non-hollow titanium dioxide pigment is included as in Comparative Example 3, the whiteness and whiteness are good, but the ink sedimentation is poor, and the discharge stability is also very poor due to this.
In addition, if the resin solid particles are not included as in Comparative Example 5, the fixing property does not appear, and the image is broken and the brightness is lowered at one time in the scratch resistance evaluation.

In addition, as in Examples 1, 2, 5 to 7, when the water-soluble organic solvent having a boiling point of 200 ° C. or less is 50% by mass or more of the total water-soluble organic solvent, the scratch resistance of the printed image is improved and good Can be obtained.
Further, when 3-methoxy-3-methyl-1-butanol and / or 2,3-butanediol is used as the water-soluble organic solvent having a boiling point of 200 ° C. or less, the dispersion stability of the coloring material is improved and the discharge stability is improved. Improves.

DESCRIPTION OF SYMBOLS 101 Inkjet recording apparatus 102 Paper feed tray 103 Paper discharge tray 104 Ink cartridge loading part 105 Operation part 131 Guide rod 132 Sub guide rod 133 Carriage 134 Recording head 135 Sub tank 141 Paper stacking part 142 Paper 143 Paper feed roller 152 Guide roller 154 Counter roller 157 Paper feed roller 161 Guide member 171 Spur roller 172 Paper discharge roller 173 Spur roller 181 Hot air heater 182 Infrared heater 183 Back heater 184 In-printing heater 201 Ink cartridge 241 Ink bag 242 Ink inlet 243 Ink outlet 244 Cartridge case

Japanese Patent No. 4902216 JP 2012-007089 A

Claims (7)

Containing water , water-soluble organic solvent, inorganic hollow particles, and resin solid particles,
The water-soluble organic solvent has a boiling point Ri is Do because only 250 ° C. or less of the solvent, the water-soluble organic solvent, a component having a boiling point of 200 ° C. or less and containing at least 50 wt%, the content of the inorganic hollow particles White inkjet ink characterized by being 4.5-8 mass% . The white inkjet ink according to claim 1 , further comprising resin hollow particles. The white inkjet ink according to claim 1 or 2, further comprising organic white pigment particles, wherein the organic white pigment particles are non-hollow. The white inkjet ink according to any one of claims 1 to 3, comprising the inorganic hollow particles as a coloring material. 5. The white inkjet ink according to claim 4, wherein the water-soluble organic solvent component having a boiling point of 200 ° C. or less contains 3-methoxy-3-methyl-1-butanol and / or 2,3-butanediol. . An ink cartridge comprising the white inkjet ink according to any one of claims 1 to 5. An image recording apparatus having a recording head for ejecting the ink cartridges, and ink containing ink, characterized in that the ink is a white ink-jet ink according to any one of claims 1 to 5 Inkjet image recording apparatus.

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