JP6735042B2 - Ink, image forming method and image forming apparatus - Google Patents

Description

The present invention relates to an ink, an image forming method and an image forming apparatus using the ink.

Conventionally, inkjet printers have used black, yellow, magenta, and cyan as reference inks.
White plain paper is used as a general recording medium. However, when a color image is formed on a medium other than white plain paper such as a transparent film as a recording medium, the color developability of the color image deteriorates. Therefore, white ink has been used for the purpose of concealing the base or reducing the transparency of the color image to improve the color developability of the color image.
Further, in window signs, illuminated signboards, etc., images are formed on a transparent film using white ink to form a wide range of white images.

Various metal oxides and pigments such as barium sulfate, calcium carbonate, and titanium oxide used as coloring materials for white ink have a large specific gravity and settle out immediately, which causes a problem in ink storage stability.
On the other hand, it is widely known that hollow particles having a small specific gravity are used as a white pigment.

Hollow particles are particles having a low specific gravity relative to the volume per particle size and good dispersibility, and there are organic hollow particles made of a resin, inorganic hollow particles made of a metal oxide, inorganic-organic mixed hollow particles, and the like. ing.
Patent Document 1 discloses an ink composed of organic particles and inorganic particles having a hollow structure.

However, even with a white ink using hollow particles, the ink is not sufficiently fixed to a medium such as a film, and there is a problem in the durability of the printing layer formed with the white ink.
As one method for improving the fixability of the ink to a non-penetrative medium such as a film, it is possible to use a hydrophobic solvent having a low SP value. However, in that case, it is necessary to improve the solvent resistance of the hollow particles, and the volume, particle size, specific gravity, etc. of the resin that forms the outer shell and core particles of the hollow particles increase, and as a result of the improvement in solvent resistance, sedimentation There was a problem that deteriorated. Therefore, the conventional inks using hollow particles have not been able to achieve both improvement in fixing property and sedimentation property. Then, an image having poor fixability, that is, poor adhesion has poor image fastness.

An object of the present invention is to provide an ink that uses hollow particles as a coloring material to suppress sedimentation of the coloring material and to form a printing layer having excellent fastness.

The above object can be achieved by the following inventions.
An ink containing hollow particles, water, an organic solvent, and resin particles,
An ink comprising an organic solvent having an SP value of 8.5 or more and 12.0 or less as the organic solvent and polyamide resin particles as the resin particles.
The unit of the SP value in the present invention is (cal/cm ³ ) ^1/2 .

According to the present invention, even when using hollow particles having a larger particle size and bulk density as compared with conventional ones, it is possible to provide an ink that not only prevents deterioration of sedimentation but also improves the fastness of an image formed by the ink. It becomes possible to provide.

1 is an overall view of an image forming apparatus according to an embodiment of the present invention. It is a schematic diagram of an example of a droplet discharge head in the present invention. It is an enlarged view of an example of a droplet discharge head in the present invention.

The present invention will be described below, but the present invention is not limited to the embodiments shown below.

<Ink>
The ink of the present invention contains at least hollow particles, water, an organic solvent, and resin particles, and if necessary, a surfactant, a defoaming agent, and other components as additives.

<Color material>
The ink of the present invention contains at least one kind selected from inorganic hollow particles, organic hollow particles, and inorganic-organic mixed hollow particles as a coloring material. Preferred are inorganic hollow particles or inorganic-organic mixed type hollow particles.

Organic hollow particles refer to so-called resin hollow particles, and as the resin composition used for the outer shell, acrylic resin such as acrylic resin, styrene-acrylic resin, cross-linking styrene-acrylic resin, urethane resin, maleic acid resin, etc. Can be mentioned. These may be used alone or in combination.

Since it is desirable that the material of the outer shell of the inorganic hollow particles is white in terms of whiteness, oxides, nitrides, oxynitrides and the like, which are less colored, are preferable.
Examples thereof include titanium, silica, calcium, aluminum, zirconium, strontium oxides, nitrides, oxynitrides, and the like. These may be used alone or in combination.
Furthermore, the organic hollow particles and the inorganic hollow particles may be used alone, or may be used in combination by mixing.

The content of hollow particles as a coloring material component in the ink is preferably 3% by mass or more and 10% by mass or less. When the amount is 3% by mass or more, the whiteness can be secured, and when the amount is 10% by mass or less, the coating film strength can be secured.

With respect to the cumulative 50% by volume particle diameter (D50) of the hollow particles, if the particle diameter is large, the pigment tends to settle after standing with time, and if the particle diameter is small, the hiding property becomes low and the whiteness decreases. Therefore, the pigment of the ordinary white ink generally secures the whiteness and the sedimentation property in the range of about 0.05 μm or more and 0.5 μm or less in volume average particle size, but in the present invention, it is 0.05 μm or more and 10 μm or more. Even in the range of not more than 0.0 μm, it becomes possible to use while securing the quality of sedimentation.
The D50 can be measured using, for example, a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrack Bell KK).

The bulk density of the hollow particles in the present invention is a dense packing bulk density (consolidation bulk density, tap bulk density), and is a density obtained by tapping a container containing a powder sample to perform dense packing. Generally, if the density is high, the sedimentation property is deteriorated, so that the density is preferably lower than the density of the ink solvent, and is preferably 1.0 g/cm ³ or less, more preferably 0.5 g/cm ³ or less. it becomes possible to use while ensuring the quality of the precipitated at .5g / cm ³ or more 4.0 g / cm ³ or less.
The bulk density can be measured using, for example, a powder measuring and evaluating device (Powder Tester TYPE: PT-E manufactured by Hosokawa Micron Corp.).

When another color ink is overcoated with the ink of the present invention as a base, examples of the pigment of the applied ink include a black pigment, a yellow pigment, a magenta pigment, a cyan pigment, an orange pigment, a green pigment, a gold color, and a silver color. Luster color pigments and metallic pigments can be used.

As the inorganic pigment, in addition to barium yellow, cadmium red, and chrome yellow, carbon black produced by a known method such as a contact method, a furnace method, or a thermal method can be used.

Further, as the organic pigment, an azo pigment, a polycyclic pigment (for example, a phthalocyanine pigment, a perylene pigment, a perinone pigment, an anthraquinone pigment, a quinacridone pigment, a dioxazine pigment, an indigo pigment, a thioindigo pigment, an isoindolinone pigment, a quinofuraron pigment, etc.) , Dye chelates (for example, basic dye chelates, acid dye chelates, etc.), nitro pigments, nitroso pigments, aniline black, etc. can be used. Among these pigments, those having a good affinity with the solvent are preferably used.

Specific examples of the pigment include carbon blacks (CI pigment black 7) such as furnace black, lamp black, acetylene black and channel black, or copper and iron (CI pigment black 11) for black. , Metal oxides such as titanium oxide, and organic pigments such as aniline black (CI Pigment Black 1).

Further, for color, 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, 138, 150, 153, 155, 180, 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, 184, 185, 190, 193, 202, 207, 208, 209, 213, 219, 224, 254, 264, 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, 15:4 (phthalocyanine blue), 16, 17:1, 56, 60, 63, C.I. I. Pigment Green 1, 4, 7, 8, 10, 17, 18, 36, and the like.

The dye is not particularly limited, and an acid dye, a direct dye, a reactive dye, and a basic dye can be used, and one kind may be used alone, or two or more kinds may be used in combination.
Examples of the dye include C.I. I. Acid Yellow 17, 23, 42, 44, 79, 142, C.I. I. Acid Red 52,80,82,249,254,289, C.I. I. Acid Blue 9,45,249, C.I. I. Acid Black 1, 2, 24, 94, C.I. I. Food Black 1, 2, C.I. I. Direct Yellow 1, 12, 24, 33, 50, 55, 58, 86, 132, 142, 144, 173, C.I. I. Direct Red 1,4,9,80,81,225,227, C.I. I. Direct Blue 1, 2, 15, 71, 86, 87, 98, 165, 199, 202, C.I. I. Dilectd Black 19, 38, 51, 71, 154, 168, 171, 195, C.I. I. Reactive Red 14, 32, 55, 79, 249, C.I. I. Reactive Black 3, 4, 35 can be mentioned.

The content of the coloring material in the ink is preferably 0.1% by mass or more and 15% by mass or less, and more preferably 1% by mass or more and 10% by mass, from the viewpoints of improving the image density, good fixing property, and ejection stability. It is as follows.

<Hollow particle dispersion>
It is also possible to produce a white ink by mixing a material such as water or an organic solvent with a pigment dispersion prepared by mixing water or a dispersant with hollow particles as a white pigment in the present invention. The hollow particle dispersion is obtained by dispersing water, hollow particles, a dispersant and, if necessary, other components and adjusting the particle size. There is a method of dispersing the hollow particles in the ink using a dispersant, and a method of introducing a hydrophilic functional group into the hollow particles to obtain a self-dispersing pigment may also be used.

Examples of the method of dispersing using a dispersant include a method of dispersing using a known low molecular type dispersant or polymer type dispersant represented by a surfactant.
As the dispersant, for example, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant or the like can be used depending on the pigment.
Takemoto Yushi Co., Ltd. RT-100 (nonionic surfactant) and naphthalenesulfonic acid Na formalin condensate can also be suitably used as the dispersant.
The dispersants may be used alone or in combination of two or more.

As a method of introducing a hydrophilic functional group into the surface of the hollow particles to obtain self-dispersibility, for example, a method of adding a functional group such as a sulfone group or a carboxyl group and making it dispersible in water can be used.
The content of the hollow particles in the hollow particle dispersion is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoint of obtaining good ejection stability and increasing the image density, 1 mass% or more and 50 mass% or less are preferable, and 0.1 mass% or more and 30 mass% or less are more preferable.

<water>
As water, for example, deionized water, ultrafiltered water, reverse osmosis water, pure water such as distilled water, or ultrapure water can be used. The type and content of water in the ink can be appropriately selected according to the purpose. The content of water in the ink is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 10% by mass or more and 90% by mass or less and 15% by mass or less from the viewpoint of the drying property of the ink and the ejection reliability. % Or more and 60 mass% or less is more preferable.

<Organic solvent>
The ink of the present invention contains an organic solvent having an SP value of 8.5 or more and 12.0 or less.
By setting the SP value of the organic solvent within the above numerical range, when forming an image on a non-penetrating medium such as a film, the affinity of the solvent for the medium is improved, the adhesion of the ink is improved, and the image fastness is improved. be able to. When the polyamide resin is used and the resin particles are uniformly dispersed in the system, a three-dimensional network structure consisting of hydrogen bonds is formed in the system due to the interaction with the organic solvent, the hollow pigment particles, and other resins, and the pigment particles are prevented from settling. It becomes possible to prevent. In addition, since the ease of forming a bond structure including hydrogen bonds in the system varies depending on the SP value of the organic solvent used, it is effective in preventing sedimentation, which is a problem when using a hollow white pigment. The SP value of the organic solvent needs to be 8.5 or more and 12 or less.

［式（Ｉ）中、Ｒは炭素数１〜４のアルキル基である。］

〔式（ＩＩ）中、Ｒ_２は炭素数１〜２のアルキル基であり、Ｒ_３は水素原子又は炭素数１〜２のアルキル基である。〕 In particular, the organic solvent contained in the ink of the present invention preferably contains at least one of the compound represented by the following general formula (I) and the compound represented by the following formula (II).

[In the formula (I), R represents an alkyl group having 1 to 4 carbon atoms. ]

[In the formula (II), R ₂ is an alkyl group having 1 to ₂ carbon atoms, and R ₃ is a hydrogen atom or an alkyl group having 1 to 2 carbon atoms. ]

R in the compound represented by the formula (I) can be used by selecting it from an alkyl group having 1 to 4 carbon atoms within a range where the SP value satisfies 8.5 or more and 12.0 or less.
R ₂ and R ₃ of the compound represented by the formula (II) can be used by selecting from alkyl groups having 1 to 2 carbon atoms within a range where the SP value satisfies 8.5 or more and 12.0 or less.

There are various calculation methods for the SP value, but the SP value in the present invention is calculated by the well-known Fedors method.
For example, in the formula (I), when R is a methyl group having 1 carbon atom, the SP value is about 9.2, and when R is a butyl group having 4 carbon atoms, the SP value is about 9.0.

Further, in the formula (II), when R ₂ is a methyl group having 1 carbon atom and R ₃ is a hydrogen atom, the SP value is about 11.8, and when R ₂ and R ₃ are ethyl groups having 2 carbon atoms, the SP value is about It becomes 8.6. The SP value of the compound of the formula (I) and the compound of the formula (II) varies depending on the kind of the combination of the substituents of R, R ₂ and R ₃ , but the SP value of the compound of the formula (I) is 9.0 to 9. .2 and the compound of formula (II) has an SP value in the range of 8.6 to 11.8.

Further, in addition to the above-mentioned solvent, an organic solvent having an auxiliary effect may be contained. Examples thereof include polyhydric alcohols, ethers such as polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, and sulfur-containing compounds.

Specific examples of the organic solvent include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, and the like. 2,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 2 ,4-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl-1, Polyhydric alcohols such as 3-pentanediol and petriol, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, propylene glycol monoethyl ether, etc. Polyhydric alcohol alkyl ethers, ethylene glycol monophenyl ether, polyhydric alcohol aryl ethers such as ethylene glycol monobenzyl ether, 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1 ,3-Dimethyl-2-imidazolidinone, ε-caprolactam, γ-butyrolactone and other nitrogen-containing heterocyclic compounds, formamide, N-methylformamide, N,N-dimethylformamide, 3-methoxy-N,N-dimethylpropione Amides, amides such as 3-butoxy-N,N-dimethylpropionamide, amines such as monoethanolamine, diethanolamine and triethylamine, sulfur-containing compounds such as dimethyl sulfoxide, sulfolane and thiodiethanol, propylene carbonate and ethylene carbonate. Can be mentioned.

As the organic solvent, it is preferable to use an organic solvent having a boiling point of 250° C. or less because it not only functions as a wetting agent but also obtains good drying properties.
The content of the organic solvent having the SP value of 8.5 or more and 12.0 or less in the ink is preferably 20% by mass or more and 60% by mass or less.
The content of the total organic solvent in the ink is not particularly limited, but is preferably 20% by mass or more and 80% by mass or less, and more preferably 20% by mass or more and 70% by mass or less from the viewpoint of the drying property of the ink.

<Resin particles>
The resin particles contained in the ink of the present invention contain at least a resin classified as a polyamide type. The resin particles are present in a state of dispersion in which they are dispersed in the solvent in the form of particles.

When the polyamide resin is used to uniformly disperse the resin particles in the system, the organic solvent interacts with the hollow pigment particles, and when other resin is contained, the system interacts with the other resin. It becomes possible to prevent the sedimentation of pigment particles by forming a three-dimensional network structure therein. Further, the SP value of the organic solvent effective for preventing sedimentation is 8.5, because the ease of forming a bond structure containing hydrogen bonds in the system varies depending on the SP value of the organic solvent used. The acid value of the polyamide-based resin having the SP value of 12.0 or less and exhibiting the effect of preventing sedimentation in combination with the organic solvent having the SP value is preferably 7.5 mgKOH/g or more and 40.0 mgKOH/g or less, and more preferably It is 9.0 mgKOH/g or more and 30.0 mgKOH/g or less, and more preferably 9.0 mgKOH/g or more and 24.0 mgKOH/g or less.

When the content (mass basis) of the organic solvent in the ink is 1, the content of the polyamide resin is preferably 0.0005 or more and 0.6 or less. Within this range, it is possible to solve the problem that a sufficient pigment sedimentation preventing effect is not exhibited due to lack of resin, and further, excessive resin causes the ink after drying to become hard and brittle, and the image fastness such as the followability to the bending of the film deteriorates. It is possible to solve the problem of being lost.

Examples of the polyamide-based resin particles used in the present invention include Disparlon AQH-800, AQ-580, AQ-600, AQ-607, AQ-610, AQ-633E (Kusumoto Kasei Co., Ltd.).
As a method for producing a polyamide resin, a known method can be applied, and a combination of a dicarboxylic acid and a diamine as a combination of monomers, for example, a dimer acid and a dimer diamine can be produced by heating and reacting. ..

The acid value of the resin can be determined by a known method. For example, the resin is dissolved in xylene and dimethylformamide 1:1 solution and titrated with a 0.1 mol/L potassium hydroxide/ethanol solution by potentiometric titration, The acid value is calculated from the titration amount of the potassium hydroxide solution until the end point. Specifically, it can be carried out based on "JIS-K2501-2003 Petroleum products and lubricants-Neutralization number test method".

The content of the polyamide resin particles in the ink is preferably 0.01% by mass or more and 3% by mass or less. Within this range, an ink having excellent sedimentation prevention and image fastness can be obtained.

Further, in addition to the above-mentioned resin, a resin having an auxiliary effect may be contained.
The type of the other resin contained in the ink is not particularly limited and may be appropriately selected depending on the purpose, for example, urethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, Examples thereof include butadiene-based resin, styrene-butadiene-based resin, vinyl chloride-based resin, acrylic styrene-based resin, and acrylic silicone-based resin.

These resins may be dissolved in an organic solvent and used, or may be used as resin particles. It is possible to obtain an ink by mixing resin particles in the state of a resin emulsion in which water is used as a dispersion medium, with a material such as a coloring material or an organic solvent. As the resin particles, those synthesized appropriately may be used, or commercially available products may be used. Further, these may be used alone or in combination of two or more kinds of resin particles.

The content of the resin to be supplementarily added is not particularly limited and may be appropriately selected depending on the purpose, but from the viewpoint of fixability and storage stability of the ink, 1% by mass relative to the total amount of the ink. 40 mass% or less is preferable and 5 mass% or more and 30 mass% or less is more preferable.

The volume average particle diameter of the resin particles is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 10 nm or more and 1,000 nm or less from the viewpoint of obtaining good fixability and high image hardness. It is more preferably 200 nm or more and more preferably 10 nm or more and 100 nm or less.
The volume average particle diameter can be measured using, for example, a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).

<Additive>
If necessary, a surfactant, a defoaming agent, an antiseptic/antifungal agent, a rust preventive, a pH adjuster and the like may be added to the ink.

<Surfactant>
As the surfactant, any of silicone-based surfactants, fluorine-based surfactants, amphoteric surfactants, nonionic surfactants, and anionic surfactants can be used.
The silicone-based surfactant is not particularly limited and can be appropriately selected according to the purpose. Among them, those that do not decompose even at high pH are preferable, and examples thereof include side chain modified polydimethylsiloxane, both-end modified polydimethylsiloxane, one-end modified polydimethylsiloxane, and side-chain both-end modified polydimethylsiloxane. Those having an oxyethylene group or a polyoxyethylene polyoxypropylene group are particularly preferable because they exhibit good properties as an aqueous surfactant. In addition, as the silicone-based surfactant, a polyether-modified silicone-based surfactant can also be used, and examples thereof include a compound having a polyalkylene oxide structure introduced into the side chain of the Si moiety of dimethylsiloxane.
Examples of the fluorinated surfactant include a perfluoroalkyl sulfonic acid compound, a perfluoroalkyl carboxylic acid compound, a perfluoroalkyl phosphoric acid ester compound, a perfluoroalkyl ethylene oxide adduct and a perfluoroalkyl ether group in the side chain. A polyoxyalkylene ether polymer compound is particularly preferable because it has a low foaming property. Examples of the perfluoroalkyl sulfonic acid compound include perfluoroalkyl sulfonic acid and perfluoroalkyl sulfonate. Examples of the perfluoroalkylcarboxylic acid compound include perfluoroalkylcarboxylic acid and perfluoroalkylcarboxylic acid salts. As the polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in its side chain, a sulfuric acid ester salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in its side chain, or a perfluoroalkyl ether group in its side chain Examples thereof include salts of polyoxyalkylene ether polymers. The counterions of the salts in these fluorine-based surfactants include Li, Na, K, NH ₄ , NH ₃ CH ₂ CH ₂ OH, NH ₂ (CH ₂ CH ₂ OH) ₂ and NH(CH ₂ CH ₂ OH). _{3 and the} like.
Examples of the amphoteric surfactant include lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine.
Examples of nonionic surfactants include polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkylamines, polyoxyethylene alkylamides, polyoxyethylene propylene block polymers, sorbitan fatty acid esters, polyoxyethylene sorbitan. Examples thereof include fatty acid esters and ethylene oxide adducts of acetylene alcohol.
Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, lauryl salt, and salt of polyoxyethylene alkyl ether sulfate.
These may be used alone or in combination of two or more.

（但し、一般式（Ｓ−１）式中、ｍ、ｎ、ａ、及びｂは、それぞれ独立に、整数を表わし、Ｒは、アルキレン基を表し、Ｒ’は、アルキル基を表す。）
上記のポリエーテル変性シリコーン系界面活性剤としては、市販品を用いることができ、例えば、ＫＦ−６１８、ＫＦ−６４２、ＫＦ−６４３（信越化学工業株式会社）、ＥＭＡＬＥＸ−ＳＳ−５６０２、ＳＳ−１９０６ＥＸ（日本エマルジョン株式会社）、ＦＺ−２１０５、ＦＺ−２１１８、ＦＺ−２１５４、ＦＺ−２１６１、ＦＺ−２１６２、ＦＺ−２１６３、ＦＺ−２１６４（東レ・ダウコーニング・シリコーン株式会社）、ＢＹＫ−３３、ＢＹＫ−３８７（ビックケミー株式会社）、ＴＳＦ４４４０、ＴＳＦ４４５２、ＴＳＦ４４５３（東芝シリコン株式会社）などが挙げられる。 The silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include side-chain modified polydimethylsiloxane, both-end modified polydimethylsiloxane, one-end modified polydimethylsiloxane, and side-modified. Examples include polydimethyl siloxane modified at both chain ends, and a polyether modified silicone surfactant having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as a modifying group shows good properties as an aqueous surfactant, preferable.
As such a surfactant, an appropriately synthesized product may be used, or a commercially available product may be used. Commercially available products can be obtained from, for example, Big Chemie Co., Ltd., Shin-Etsu Chemical Co., Ltd., Toray Dow Corning Silicone Co., Ltd., Nippon Emulsion Co., Ltd., Kyoeisha Kagaku, etc.
The polyether-modified silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the polyalkylene oxide structure represented by the general formula (S-1) is represented by dimethylpolyethylene. Examples thereof include those introduced into the side chain of the Si portion of siloxane.

(However, in the general formula (S-1), m, n, a, and b each independently represent an integer, R represents an alkylene group, and R′ represents an alkyl group . )
As the above polyether-modified silicone-based surfactant, commercially available products can be used, and for example, KF-618, KF-642, KF-643 (Shin-Etsu Chemical Co., Ltd.), EMALEX-SS-5602, SS-. 1906EX (Nippon Emulsion Co., Ltd.), FZ-2105, FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163, FZ-2164 (Toray Dow Corning Silicone Co., Ltd.), BYK-33, BYK-387 (Big Chemie Co., Ltd.), TSF4440, TSF4452, TSF4453 (Toshiba Silicon Co., Ltd.), etc. are mentioned.

上記一般式（Ｆ−１）で表される化合物において、水溶性を付与するためにｍは０〜１０の整数が好ましく、ｎは０〜４０の整数が好ましい。
一般式（Ｆ−２）
Ｃ_ｎＦ_2ｎ+1−ＣＨ₂ＣＨ（ＯＨ）ＣＨ₂−Ｏ−（ＣＨ₂ＣＨ₂Ｏ）_ａ−Ｙ
上記一般式（Ｆ−２）で表される化合物において、ＹはＨ、又はＣｎＦ_２ｎ＋１でｎは１〜６の整数、又はＣＨ_２ＣＨ（ＯＨ）ＣＨ_２−ＣｎＦ_２ｎ＋１でｎは4〜６の整数、又はＣｐＨ_２ｐ＋１でｐは１〜１９の整数である。ａは４〜１４の整数である。
上記のフッ素系界面活性剤としては市販品を使用してもよい。 この市販品としては、例えば、サーフロンＳ−１１１、Ｓ−１１２、Ｓ−１１３、Ｓ−１２１、Ｓ−１３１、Ｓ−１３２、Ｓ−１４１、Ｓ−１４５（いずれも、旭硝子株式会社製）；フルラードＦＣ−９３、ＦＣ−９５、ＦＣ−９８、ＦＣ−１２９、ＦＣ−１３５、ＦＣ−１７０Ｃ、ＦＣ−４３０、ＦＣ−４３１（いずれも、住友スリーエム株式会社製）；メガファックＦ−４７０、Ｆ−１４０５、Ｆ−４７４（いずれも、大日本インキ化学工業株式会社製）；ゾニール（Ｚｏｎｙｌ）ＴＢＳ、ＦＳＰ、ＦＳＡ、ＦＳＮ−１００、ＦＳＮ、ＦＳＯ−１００、ＦＳＯ、ＦＳ−３００、ＵＲ、キャプストーンＦＳ−３０、ＦＳ−３１、ＦＳ−３１００、ＦＳ−３４、ＦＳ−３５（いずれも、Ｃｈｅｍｏｕｒｓ社製）；ＦＴ−１１０、ＦＴ−２５０、ＦＴ−２５１、ＦＴ−４００Ｓ、ＦＴ−１５０、ＦＴ−４００ＳＷ（いずれも、株式会社ネオス社製）、ポリフォックスＰＦ−１３６Ａ，ＰＦ−１５６Ａ、ＰＦ−１５１Ｎ、ＰＦ−１５４、ＰＦ−１５９（オムノバ社製）、ユニダインＤＳＮ-４０３Ｎ（ダイキン工業株式会社製）などが挙げられ、これらの中でも、良好な印字品質、特に発色性、紙に対する浸透性、濡れ性、均染性が著しく向上する点から、Ｃｈｅｍｏｕｒｓ社製のＦＳ−３１００、ＦＳ−３４、ＦＳ−３００、株式会社ネオス製のＦＴ−１１０、ＦＴ−２５０、ＦＴ−２５１、ＦＴ−４００Ｓ、ＦＴ−１５０、ＦＴ−４００ＳＷ、オムノバ社製のポリフォックスＰＦ−１５１Ｎ及びダイキン工業株式会社製のユニダインＤＳＮ-４０３Ｎが特に好ましい。 The fluorine-based surfactant is preferably a fluorine-substituted compound having 2 to 16 carbon atoms, more preferably a fluorine-substituted compound having 4 to 16 carbon atoms.
Examples of the fluorinated surfactant include perfluoroalkyl phosphate ester compounds, perfluoroalkylethylene oxide adducts, and polyoxyalkylene ether polymer compounds having a perfluoroalkyl ether group in the side chain. Among these, a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in its side chain is preferable because it has a low foaming property, and particularly, a fluorine-based compound represented by the general formula (F-1) or the general formula (F-2). Surfactants are preferred.

In the compound represented by the general formula (F-1), m is preferably an integer of 0 to 10 and n is preferably an integer of 0 to 40 in order to impart water solubility.
General formula (F-2)
_{C n F 2n + 1- CH 2} CH (OH) CH 2 -O- (CH 2 CH 2 O) a -Y
In the compound represented by the general formula (F-2), Y is H, or CnF _2n+1 and n is an integer of 1 to 6, or CH ₂ CH(OH)CH ₂ -CnF _2n+1 and n is 4 to 6. An integer, or CpH _2p+1 and p is an integer of 1 to 19. a is an integer of 4-14.
A commercially available product may be used as the above-mentioned fluorine-based surfactant. Examples of commercially available products include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, 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 Dainippon Ink and Chemicals, Inc.); Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR, Capstone FS-30, FS-31, FS-3100, FS-34, FS-35 (all manufactured by Chemours); FT-110, FT-250, FT-251, FT-400S, FT-150, FT-. 400SW (all manufactured by Neos Co., Ltd.), Polyfox PF-136A, PF-156A, PF-151N, PF-154, PF-159 (manufactured by OMNOVA), Unidyne DSN-403N (manufactured by Daikin Industries, Ltd.) Among them, good printing quality, especially color developability, penetrability to paper, wettability, even dyeability, from the point of being significantly improved, FS-3100, FS-34, FS-34 manufactured by Chemours. 300, FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW made by Neos Co., Ltd., Polyfox PF-151N made by Omnova Co., and Unidyne DSN-made by Daikin Industries, Ltd. 403N is particularly preferred.

The content of the surfactant in the ink is appropriately selected depending on the intended purpose without any limitation, but it is 0.001 mass% from the viewpoint of excellent wettability and ejection stability and improving image quality. % Or more and 5 mass% or less is preferable, and 0.05 mass% or more and 5 mass% or less is more preferable.

<Antifoam>
The defoaming agent is not particularly limited, and examples thereof include a silicone defoaming agent, a polyether defoaming agent, and a fatty acid ester defoaming agent. These may be used alone or in combination of two or more. Among these, a silicone-based defoaming agent is preferable because of its excellent foam breaking effect.

<Antiseptic and fungicide>
The antiseptic/antifungal agent is not particularly limited, and examples thereof include 1,2-benzisothiazolin-3-one.

<Rust preventive>
The rust preventive agent is not particularly limited, and examples thereof include acid sulfite and sodium thiosulfate.

<pH adjuster>
The pH adjuster is not particularly limited as long as the pH can be adjusted to 7 or higher, and examples thereof include amines such as diethanolamine and triethanolamine.

The physical properties of the ink are not particularly limited and may be appropriately selected depending on the purpose. For example, the viscosity, surface tension, pH and the like are preferably in the following ranges.
The viscosity of the ink at 25° C. is preferably 5 mPa·s or more and 30 mPa·s or less, from the viewpoint that the printing density and character quality are improved and good ejection properties are obtained, and 5 mPa·s or more and 25 mPa·s or less are preferable. More preferable. Here, as the viscosity, for example, a rotary viscometer (RE-80L manufactured by Toki Sangyo Co., Ltd.) can be used. The measurement conditions are 25° C., standard cone rotor (1°34′×R24), sample liquid volume 1.2 mL, rotation speed 50 rpm, and 3 minutes.
The surface tension of the ink is preferably 35 mN/m or less, and more preferably 32 mN/m or less at 25° C., since the ink is preferably leveled on the recording medium and the drying time of the ink is shortened.
The pH of the ink is preferably 7 to 12, and more preferably 8 to 11 from the viewpoint of preventing the corrosion of the metal member with which the ink comes into contact.

<Recording medium>
The recording medium is not particularly limited, and plain paper, glossy paper, special paper, cloth, and the like can be used, but good image formation can be performed using a non-permeable substrate.
The non-permeable base material is a base material having a surface having low water permeability and low absorbability, and includes a material that does not open to the outside even if there are many cavities inside, and more quantitatively. , Bristow method refers to a substrate having a water absorption amount of 10 mL/m ² or less from the start of contact to 30 msec ^1/2 .
As the impermeable substrate, for example, a plastic film such as a vinyl chloride resin film, a polyethylene terephthalate (PET) film, polypropylene, polyethylene, a polycarbonate film can be preferably used.

<Image forming apparatus and image forming method>
The ink of the present invention can be suitably used for various image forming apparatuses using an ink jet recording system, such as printers, facsimile machines, copying machines, printer/fax/copier multifunction machines, and three-dimensional modeling apparatuses.

In the present application, the recording device and the recording method are a device capable of ejecting ink, various treatment liquids, and the like onto a recording medium, and a method of performing recording using the device. The recording medium means a medium to which ink or various treatment liquids can be attached even temporarily.

This image forming apparatus is provided with a head portion for ejecting ink, and the ink is applied with at least one kind of stimulus selected from heat, pressure, and vibration, and the recording ink is ejected to form an image. It is possible to record. Further, not only the head, but also means for feeding, conveying, and discharging the recording medium, and other devices such as a pre-processing device and a post-processing device can be included.

The image forming apparatus and the image forming method may have a heating means used in the heating step and a drying means used in the drying step. The heating means and the drying means include, for example, means for heating and drying the printing surface or the back surface of the recording medium. The heating means and the drying means are not particularly limited, but, for example, a warm air heater or an infrared heater can be used. Heating and drying can be performed before printing, during printing, after printing, and the like.

Further, the image forming apparatus and the image forming method are not limited to those in which a significant image such as a character or a figure is visualized by ink. For example, it also includes one that forms a pattern such as a geometric pattern and one that models a three-dimensional image.
Further, the image forming apparatus includes both a serial type device that moves the ejection head and a line type device that does not move the ejection head unless otherwise limited.
Further, in this image forming apparatus, not only a desktop type but also a wide image forming apparatus capable of printing on an A0 size recording medium, for example, a continuous paper wound in a roll is used as a recording medium. It also includes a continuous form printer that can handle.

As an example of the inkjet recording method of the present invention, a step of applying an ink (white ink) containing a white pigment as a color material to a recording medium, and a step of applying black (K), cyan (C), and magenta (M) ), and a recording step of recording using an ink having a color material such as yellow (Y). At this time, the white ink may be applied to the entire surface of the recording medium, or may be applied to a part of the recording medium. When it is applied to a part of the recording medium, for example, it may be applied to the same part as the part to be recorded, or may be partly common to the part to be recorded, or may be applied to an independent part. May be.

When the white ink is used, the white ink is applied to the surface of the recording medium, and black (K), cyan (C), magenta (M), yellow (Y), orange (Or), green other than white is applied on the white ink. Ink of another color such as (Gr) may be overlaid and recorded. According to this method, for example, even when a transparent film is used, since the white ink is used as a base to be attached to the color ink in an overlapping manner, the visibility of recording with the color ink can be secured. Since the ink of the present invention has good drying property, high gloss, scratch resistance, etc. even for a non-permeable recording medium, a white ink is applied to the non-permeable recording medium such as a transparent film to improve visibility. Can be applied.

The ink of the present invention is not limited to the inkjet recording method and can be widely used. In addition to the inkjet recording method, for example, a blade coating method, a gravure coating method, a gravure offset coating method, a bar coating method, a roll coating method, a knife coating method, an air knife coating method, a comma coating method, a U comma coating method, an AKKU coating method. The smoothing coating method, the micro gravure coating method, the reverse roll coating method, the four to five roll coating method, the dip coating method, the curtain coating method, the slide coating method, the die coating method, the spray coating method and the like can be mentioned.

As an example of the embodiment, when the white ink is applied to the entire surface of the recording medium, it is applied by a coating method other than the inkjet recording method, and when recording with an ink of a color other than white, the inkjet recording method is used. It is possible to do so.
As another embodiment, it is possible to record by using an inkjet recording method for both recording using a white ink and recording using an ink of a color other than white.

An example of the image forming apparatus will be described based on FIG.
The inkjet recording apparatus 300 to which the present invention is applied includes a recording medium conveying unit 301, an image forming unit 304, and a winding device 308.
The recording medium transport unit 301 includes a sheet feeding device 307 and a plurality of transport rollers 302. The recording medium 203 is continuous paper (roll paper) wound in a roll shape, and is unwound from the paper feeding device 307 by the transportation roller 302, transported on the platen, and wound by the winding device 308.
The recording medium includes, for example, plain paper, high-quality paper, thin paper, thick paper, recording paper, OHP sheet, synthetic resin film, metal thin film, and/or other media capable of forming an image with ink or the like on its surface. Although roll paper is used in this embodiment, the recording medium on which an image can be formed is not limited to roll paper.

As shown in FIG. 2, the image forming unit 304 is a full line type head, and is black (K), cyan (C), magenta (M), yellow (Y), orange from the upstream side in the recording medium conveyance direction. It is configured by disposing seven recording heads 304K, 304C, 304M, 304Y, 304Or, 304Gr, 304W that are compatible with (Or), green (Gr), and white (W).
For example, the black (K) recording head 304K has a print area width obtained by arranging four short head units 304K-1, 304K-2, 304K-3, 304K-4 in a direction orthogonal to the transport direction in a zigzag pattern. Has been secured.

FIG. 3 is an enlarged view of the head unit 304K-1. As shown in the figure, a large number of print nozzles 310 are arranged on the nozzle surface 309 of 304K-1 along the longitudinal direction of the head unit 304K-1 to form a nozzle row. In this embodiment, the number of nozzle rows is one, but a plurality of rows may be provided. The other recording heads 304C, 304M, 304Y, 304Or, 304Gr, 304W have the same configuration, and the seven recording heads 304K, 304C, 304M, 304Y, 304Or, 304Gr, 304W hold the same pitch and are in the conveyance direction. Are arranged in. As a result, it is possible to form an image over the entire width of the printing area with one recording operation.

Further, as shown in FIG. 1 as a post-processing unit in the image forming apparatus, a post-processing unit 305 for adhering the post-processing liquid to the recording medium after the image forming process, and a recording medium 203 to which the post-processing liquid is applied are dried. A post-treatment drying section 306 may be provided.
The post-treatment and post-drying device comprises heat rollers 313 and 314 as shown in FIG. 1, for example. According to this apparatus, the continuous paper to which the post-treatment liquid is attached is transported to the heat roller by the transport roller. The heat roller is heated to a high temperature, and the continuous paper to which the post-treatment liquid has been adhered is dried by evaporation of water due to contact heat transfer from the heat roller. The drying means is not limited to this, and an infrared drying device, a microwave drying device, hot air, or the like may be applied. For example, a heat roller and a warm air device may be combined instead of using a single device. good.

<Image formation>
The image-formed product of the present invention has an image formed by using the ink of the present invention on a recording medium. A recorded matter can be obtained by recording with an inkjet recording apparatus and an inkjet recording method.

Hereinafter, with respect to the ink of the present invention, verification examples of the example sample and the comparative example sample will be shown. The present invention is not limited to the examples shown below.
In the following description, "%" means "mass%" unless otherwise specified.
In the following, the unit of SP value is (cal/cm ³ ) ^1/2 and the unit of acid value of resin particles is [mgKOH/g].

[Measurement of bulk density]
The bulk density described here refers to a densely packed bulk density, and can be measured by a known method.
A cap is attached to the opening of a bulk density measuring cup made of stainless steel having a volume of 100 cm ³ and a mass α, measurement particles are filled up to the top of the cap, and then a cap cover is attached to prepare a measurement sample. A powder tester (TYPE:PT-E) manufactured by Hosokawa Micron Co., Ltd. is used as a measuring device, the above-mentioned measurement sample is set in a tapping holder, and tapping is performed for 10 minutes at a speed of once/second. After completion of tapping, the mass β of the measuring cup containing the sample is measured.
Bulk density is calculated by dividing the sample mass (β-α) by the volume of the measuring cup, 100 cm ³ . Close-packed bulk density [g/cm ³ ] = (β-α)/100

[Synthesis example of hollow particles]
Hollow particles can be synthesized by a known method.
<Hollow particle synthesis example 1>
A solution obtained by mixing 50 g of 4-vinylpyridine, 2 g of divinylbenzene, 28 g of styrene, 20 g of butyl acrylate, 100 g of toluene, and 2 g of 3,5,5-trimethylhexanoyl peroxide was added to 400 g of water in which 10 g of polyvinyl alcohol was dissolved. The emulsion tester ET-3A manufactured by the company was stirred at a rotation speed of 10000 rpm for 40 minutes to obtain a suspension in which oil droplets of 1.0 to 5.0 μm were dispersed in water. The suspension was placed in a 1000 ml separable flask and stirred at 150° C. for 15 hours at 70° C. under a nitrogen atmosphere to obtain polymer particles. The flask was opened and left at room temperature for 18 r to remove volatile substances to obtain [hollow particles 1] (organic hollow particles) having a particle diameter (D50) of 2.7 μm. The bulk density was 1.02 g/cm ³ .

<Hollow particle synthesis example 2>
[Hollow particle 2] (organic hollow particle) having a particle diameter (D50) of 4.5 μm was obtained in the same manner as in Hollow particle synthesis example 1 except that the emulsification rotation speed was changed to 8000 rpm and the stirring time was changed to 20 minutes. The bulk density was 0.85 g/cm ³ .

<Hollow particle synthesis example 3>
15 g of an ethyl silicate ethanol solution having a silica conversion concentration of 40%, 5 g of isopropanol, 40 g of a 1.7% hydrochloric acid aqueous solution, and 40 g of a 1.0% ammonium aqueous solution were stirred at 200 rpm for 30 minutes, and water was added to the mixture to give a solid content of 6%. A silica hydrolyzate of was prepared. 200 g of this hydrolyzed silica and 4 g of ion-exchanged water were mixed to prepare a slurry containing silica particles. Using a spray dryer (SPRAY DRYER SD-1000, manufactured by Tokyo Rika Kikai Co., Ltd.), this slurry was subjected to an inlet temperature of 160° C., an outlet temperature of 80° C., a hot air amount of 4.5 m ³ /min, and a spraying pressure: Spray granulation was performed under the spray conditions of 150 kPa and a flow rate of 100 ml/hour to obtain [hollow particles 3] (silica hollow particles) having a particle diameter (D50) of 2.5 μm. The bulk density was 0.50 g/cm ³ .

<Hollow particle synthesis example 4>
100 g of styrene monomer particles (SX-130 manufactured by Soken Chemical Industry Co., Ltd.) having an average particle diameter of 1.3 μm, 15 g of titanium oxide particles and 10 g of polymethylmethacrylate were hybridized under room temperature environment (NHS-1 Nara Kikai Seisakusho). The mixture was stirred at a peripheral speed of 90 m/s for 5 minutes to obtain spherical styrene-titanium oxide composite particles.
The obtained composite particles were heated to 800° C. at a heating rate of 10° C./min in an oxygen atmosphere, and fired at 800° C. for 3 hours. Then, it was cooled to room temperature at a temperature decrease rate of 20° C./min to obtain [hollow particles 4] (titanium oxide hollow particles) having a particle diameter (D50) of 4.6 μm. The bulk density was 3.4 g/cm ³ .

<Hollow particle synthesis example 5>
85 g of styrene monomer particles (SX-500 manufactured by Soken Chemical Industry Co., Ltd.) having an average particle diameter of 5.0 µ were mixed with 15 g of colloidal silica having an average particle diameter of 0.025 µm and alumina sol having an average particle diameter of 0.02 µm, and the mixture was allowed to stand in a room temperature environment. Then, the mixture was stirred for 10 minutes at a peripheral speed of 80 m/s with a hybridizer (NHS-1 manufactured by Nara Kikai Seisakusho) to obtain spherical styrene-alumina-silica composite particles.
The obtained composite particles were heated to 900° C. at a heating rate of 20° C./min in an oxygen atmosphere and calcined at 900° C. for 3 hours. Then, it was cooled to room temperature at a temperature decrease rate of 20° C./min to obtain [hollow particles 4] (alumina/silica hollow particles) having a particle diameter (D50) of 9.5 μm. The bulk density was 0.95 g/cm ³ .

[Synthesis example of pigment dispersion]
<Preparation Example 1 of pigment dispersion>
In a beaker, 5 g of polyoxyethylene styrenated phenyl ether was dissolved in 200.0 g of high pure water, 50 g of the above [hollow particles 1] was added, and the mixture was stirred with a homogenizer manufactured by Nippon Seiki Seisakusho at 10,000 rpm for 30 minutes. The resulting organic white pigment component dispersion was treated with an ultrasonic homogenizer US-300T (chip φ26) manufactured by Nippon Seiki Seisakusho at 200 μA for 1 hour while cooling with water, and the resulting pigment particle dispersion was DYNO manufactured by Shinmaru Enterprises Co., Ltd. -Mil multi-lab type zirconia beads with a particle diameter of 2 mm are used as media particles, the bead packing rate is 70% by volume, the stirring blade peripheral speed is 8 m/s, and the batch processing is performed for 30 minutes. Then, 20-pass dispersion treatment was performed at a pressure of 100 MPa. Then, filtration with a membrane filter was performed to obtain [Pigment dispersion liquid 1] having 20% by mass of hollow particles.

<Preparation Example 2 of Pigment Dispersion Liquid>
Preparation of Pigment Dispersion 8 g of polyoxyethylene styrenated phenyl ether of Preparation Example 1, 500 g of high-purity water, and 65 g of [hollow particles 1] to [hollow particles 2] were used in the same manner, except that [pigment dispersion of 12% by mass of hollow particles was used]. Liquid 2] was obtained.

<Preparation example 3 of pigment dispersion liquid>
Dissolving 10.0 g of DISPERBYK-2008 (manufactured by BYK) in 300 g of high-purity water, and stirring with a homogenizer manufactured by Nippon Seiki Seisakusho at 5000 rpm for 30 minutes, 50.0 g of [hollow particles 3] was added and stirred at 10000 rpm for 30 minutes. It was
The resulting pigment dispersion liquid was treated with an ultrasonic homogenizer US-300T (tip φ26) manufactured by Nippon Seiki Seisakusho Co., Ltd. at 200 μA for 1 hour while being water-cooled and filtered through a membrane filter to obtain a pigment dispersion containing 14% by mass of hollow particles. Liquid 3] was obtained.

[Preparation Example 4 of Pigment Dispersion Liquid>
[Pigment Dispersion Liquid 4] having 27% by weight of hollow particles was obtained in the same manner except that 100 g of high-purity water in Preparation Example 3 of Pigment Dispersion Liquid was used and [Hollow Particle 3] was changed to 30 [Hollow Particle 4].

<Preparation Example 5 of Pigment Dispersion Liquid>
High-pure water of Preparation Example 1 of Pigment Dispersion Liquid was set to 200 g, and [Hollow Particle 1] was changed to 60 g of SX866(A) manufactured by JSR Corporation having a particle size (D50) of 0.3 μm and a bulk density of 0.3 g/cm ^3. To obtain [Pigment Dispersion Liquid 5] having 25% by mass of hollow particles.

<Preparation Example 6 of Pigment Dispersion Liquid>
High-pure water of Preparation Example 1 of Pigment Dispersion Liquid was changed to 200 g, and the hollow particles were changed to 60 g of Sirinax manufactured by Nittetsu Mining Co., Ltd. having a particle diameter (D50) of 0.08 μm and a bulk density of 0.03 g/cm ^3. [Pigment dispersion 6] having 25% by mass of hollow particles was obtained.

<Preparation Example 7 of Pigment Dispersion Liquid>
[Pigment Dispersion Liquid 7] having 12% by mass of hollow particles was obtained in the same manner except that [Hollow Particle 3] in Preparation Example 3 of the pigment distribution line station was changed to 50 g of [Hollow Particle 5].

Table 1 shows the types, physical properties, and concentrations of the hollow particles in Pigment Dispersions 1 to 7.

[Synthesis example of polyamide resin]
<Synthesis Example 1: Synthesis of polyamide resin A>
112.5 parts (0.77 mol) of adipic acid and 16.9 parts of xylene were weighed into a 1-liter four-necked flask equipped with a stirrer, a temperature controller, a water separator, and a nitrogen inlet tube, and 50 Warmed to °C. Next, 308 parts (0.62 mol) of dimer diamine was gradually added, and the mixture was stirred at 150° C. for 60 minutes. Further, the mixture was gently heated to 175° C. and dehydration reaction was performed for 150 minutes to obtain polyamide resin A. The acid value of the obtained polyamide resin A was 40 mgKOH/g.
(Preparation of Aqueous Dispersion of Polyamide Resin A)
20 parts of the obtained polyamide resin A, 5 parts of polyoxyethylene-2-ethylhexyl ether, and 15 parts of propylene glycol monomethyl ether were mixed, and further heated to 120° C. and dissolved. After dissolution, 2 parts of N,N'-dimethylethanolamine was added and mixed.
The above mixture was gradually added to a 500 ml four-necked flask containing 203 parts of high-purity water heated to 40° C., stirred at 40° C. for 10 minutes after the addition, and then allowed to stand in an 80° C. constant temperature bath for 24 hours. An aqueous dispersion of polyamide resin A was obtained.

<Synthesis Example 2: Synthesis of polyamide resin B>
Adipic acid of Synthesis Example 1 of polyamide resin was changed to 354 parts (0.6 mol) of dimer acid, 53.1 parts of xylene, and 46.5 parts (0.4 mol) of dimer diamine to dimer diamine. A polyamide resin B was obtained in the same manner as in Synthesis Example 1 except for the above. The acid value of the obtained polyamide resin B was 63 mgKOH/g.
(Preparation of Aqueous Dispersion of Polyamide Resin B>
In the preparation of the aqueous dispersion of the polyamide resin A, 20 parts of the polyamide resin A is used as 20 parts of the polyamide resin B, and 2 parts of N,N′-dimethylethanolamine is used as 3 parts of N,N′-dimethylethanolamine. A water dispersion of polyamide resin B was obtained in the same manner as in the preparation of water dispersion of polyamide resin A, except that

[Preparation of ink]
The following components (i) to (vi) are used as ink components.
(I) Pigment dispersion (ii) Organic solvent (iii) Resin
(Iv) Surfactant KF-618 (manufactured by Shin-Etsu Chemical Co., Ltd.)
(V) pH adjuster 2-amino-2-ethyl-1,3-propanediol (manufactured by Tokyo Chemical Industry Co., Ltd.)
(Vi) Water After mixing and stirring the above-mentioned (iv) surfactant, (v) pH adjuster, (vi) water, (ii) organic solvent and (iii) resin, (i) pigment dispersion is further added and mixed and stirred. Then, an ink was prepared.

In the following examples, the following polyamide-based resin was used in addition to the above-mentioned polyamide-based resin A and polyamide-based resin B.
The polyamide resins used in the examples and their acid values (unit: mgKOH/g) are as follows.
・Polyamide resin A (acid value: 40)
・Polyamide resin B (acid value: 63)
-Polyamide resin C (Kusumoto Kasei Co., Ltd. Disparlon AQH800 acid value: 7.5)
-Polyamide resin D (Disparlon AQ580 manufactured by Kusumoto Kasei Co., Ltd. acid value: 9.2)
・Polyamide resin E (Disparlon AQ633E, acid value: 22.5, manufactured by Kusumoto Kasei Co., Ltd.)
-Polyurethane resin A (Kusumoto Kasei Co., Ltd. NeoRez R-966 acid value 19)

[Example 1]
An organic solvent having a SP value of 9.2 where R in the formula (I) is 9.2, a surfactant, a pH adjusting agent, and water are added to a beaker and stirred for 30 minutes with a magnetic stirrer, and then the acid value is 7.5. Polyamide resin C was added and stirred for 30 minutes, [Pigment dispersion 3] was added, and stirred for another 30 minutes to obtain an ink of Example 1. The compounding ratio of the materials to be added was the compounding ratio shown in Table 2.

[Example 2]
The organic solvent of the ink of Example 1 was used as an organic solvent in which R ₂ and R ₃ of the formula (II) each have 2 carbon atoms and 2 carbon atoms, and an SP value of 8.6, and a polyamide resin was a polyamide resin having an acid value of 63. An ink of Example 2 was obtained in the same manner as in Example 1 except that the pigment dispersion liquid was changed to [Pigment dispersion liquid 4].

[Example 3]
The organic solvent of the ink of Example 1 was used as an organic solvent having an SP value of 9.0 with R of formula (I), a polyamide resin as a polyamide resin D having an acid value of 9.2, and a pigment dispersion liquid. An ink of Example 3 was obtained in the same manner as in Example 1 except that [Pigment dispersion 2] was used.

[Example 4]
An ink of Example 4 was obtained in the same manner as in Example 1 except that the polyamide resin of the ink of Example 1 was changed to polyamide resin A having an acid value of 40 and the pigment dispersion liquid was changed to pigment dispersion liquid 1.

[Example 5]
In the formula (II), R ₂ has 1 carbon atom and R ₃ is hydrogen, an organic solvent having an SP value of 11.8, a surfactant, a pH adjusting agent, and water are added to a beaker and stirred with a magnetic stirrer for 30 minutes, and then the acid is added. Polyamide resin E having a value of 22.5 was added and stirred for 30 minutes, then [Pigment dispersion 2] was added and stirred for 30 minutes, and then [Pigment dispersion 3] was added and stirred for 30 minutes. I got the ink.

[Example 6]
In the formula (I), R has a carbon number of 1, an organic solvent having an SP value of 9.2, a surfactant, a pH adjusting agent, and water are added to a beaker and stirred with a magnetic stirrer for 30 minutes, and then the polyurethane resin A is added. After adding and stirring for 30 minutes, polyamide resin B having an acid value of 63 was added and stirred for 30 minutes, and then pigment dispersion liquid 4 was added and stirred for 30 minutes to obtain an ink of Example 6.

[Example 7]
An ink of Example 7 was obtained in the same manner as in Example 6 except that the polyamide resin of the ink of Example 6 was changed to polyamide resin E having an acid value of 22.5 and the pigment dispersion was changed to [Pigment dispersion 3]. It was

[Example 8]
An ink of Example 8 was obtained in the same manner as in Example 7, except that the pigment dispersion liquid of the ink of Example 7 was changed to [Pigment dispersion liquid 5] and the amount of organic solvent and the amount of polyamide resin were changed.

[Example 9]
An ink of Example 9 was obtained in the same manner as in Example 1 except that the pigment dispersion liquid of the ink of Example 1 was changed to [Pigment dispersion liquid 6].

[Example 10]
An ink of Example 10 was obtained in the same manner as in Example 1 except that the pigment dispersion liquid of the ink of Example 1 was changed to [Pigment dispersion liquid 7].

[Example 11]
Example 1 except that the organic solvent of the ink of Example 1 is an organic solvent having an SP value of 9.2 for R in formula (I) and 1,2-propanediol having an SP value of 13.5. An ink of Example 11 was obtained in the same manner as in.

[Comparative Example 1]
An organic solvent having an SP value of 9.2 where R in the formula (I) is 9.2, a surfactant, a pH adjuster, and water are added to a beaker and stirred for 30 minutes with a magnetic stirrer, and [Pigment dispersion 4] is added. Then, the ink of Comparative Example 1 was obtained by further stirring for 30 minutes. The compounding ratio of the materials to be added was as shown in Table 3.

[Comparative example 2]
1,2-Propanediol having an SP value of 13.5, a surfactant, a pH adjuster and water are added to a beaker and stirred for 30 minutes with a magnetic stirrer, and then a polyamide resin A having an acid value of 40 is added to the mixture. The ink of Comparative Example 2 was obtained by stirring for 1 minute, adding Pigment Dispersion Liquid 2 and further stirring for 30 minutes.
The compounding ratio of the materials to be added was as shown in Table 3.

[Comparative Example 3]
1,2-Propanediol having an SP value of 13.5, a surfactant, a pH adjuster, and water are added to a beaker and stirred for 30 minutes with a magnetic stirrer, [Pigment dispersion 1] is added, and further stirred for 30 minutes. An ink of Comparative Example 3 was obtained. The compounding ratio of the materials to be added was as shown in Table 3.

[Comparative Example 4]
In the formula (I), R has a carbon number of 1, an organic solvent having an SP value of 9.2, a surfactant, a pH adjusting agent, and water are added to a beaker and stirred with a magnetic stirrer for 30 minutes, and then the polyurethane resin A is added. The pigment dispersion liquid 3 was added and stirred for 30 minutes, and then the pigment dispersion liquid 3 was added and stirred for 30 minutes to obtain an ink of Comparative Example 4.

[Evaluation]
<Hollow particle sedimentation evaluation>
20 mL of the prepared ink was placed in a transparent sample bottle (capacity: about 20 mL), and the ink composition was allowed to stand in a 70° C. environment for 14 days, and the ink composition was visually observed to evaluate the pigment sedimentation property. I went. The results are shown in Table 4. The evaluation criteria at this time are as follows.
⊚: Pigment is not observed to settle in the lower part of the container. ◯: Pigment is observed to be settling in the lower part of the container. However, shaking the sample bottle 3 times restores the state of non-precipitation. : Pigment is observed to have settled in the lower part of the container, and even if the sample bottle is shaken three times or more, it does not return to the unsettled state

<Image fastness evaluation>
The prepared ink was filled in an inkjet printer, a solid image was printed on a PVC film (IJ4334C manufactured by 3M), and dried at 60° C. for 30 minutes.
The solid portion of the image was evaluated by a cross-cut peeling test using an adhesive tape (ISO adhesive tape manufactured by TQC) by the degree of peeling of 100 test squares. The results are shown in Table 4. The evaluation criteria at this time are as follows.
⊚: No peeling is seen in any of the 100 squares.
◯: 1 to 5 of 100 squares are peeled off.
X: Peeling is seen in 6 or more of 100 squares.

203 recording medium 300 inkjet recording apparatus 301 recording medium conveying section 302 conveying roller 304 image forming section 304K, 304C, 304M, 304Y, 304Or, 304Gr, 304W recording head 304K-1, 304K-2, 304K-3, 304K-4 head Unit 305 Post-processing unit 306 Post-processing post-drying unit 307 Paper feeding device 308 Winding device 309 Nozzle surface 310 Printing nozzles 313, 314 Heat roller

JP2012-007089A

Claims (11)

An ink containing hollow particles, water, an organic solvent, and resin particles,
The resin particles include polyamide resin particles having an acid value of 7.5 mgKOH/g or more and 40.0 mgKOH/g or less,
The organic solvent contains an organic solvent having an SP value of 8.5 or more and 12.0 or less,
The organic solvent having an SP value of 8.5 or more and 12 or less contains at least one compound represented by the following general formula (I) and a compound represented by the following general formula (II). The ink according to any one of claims 1 to 9.

[In the formula (I), R represents an alkyl group having 1 to 4 carbon atoms. ]

[In the formula (II), R ₂ is an alkyl group having 1 to ₂ carbon atoms, and R ₃ is a hydrogen atom or an alkyl group having 1 to 2 carbon atoms. ] The ink according to claim 1, wherein the hollow particles are inorganic hollow particles, organic hollow particles, or inorganic-organic mixed hollow particles. The ink according to claim 1 or 2, wherein the hollow particles are inorganic hollow particles or inorganic-organic mixed type hollow particles. 4. The ink according to claim 1, wherein the hollow particles have a particle diameter (D50) of 0.05 μm or more and 10.0 μm or less. 5. The ink according to claim 1, wherein the hollow particles have a bulk density of 0.5 g/cm ³ or more and 4.0 g/cm ³ or less. The ink according to any one of claims 1 to 5, wherein the acid value of the polyamide resin is not more than 9.0mgKOH / g or more 24.0mgKOH / g. The ink according to any one of claims 1 to 6 content is characterized in that 3 mass% or less than 0.01 wt% in the ink of the polyamide resin particles. The content of the polyamide resin in the ink is 0.0005 or more and 0.6 or less, when the content (mass basis) of the hollow particles in the ink is 1. The ink according to any one of 1 to 7 . The ink according to any one of claims 1 to 8 , wherein the content of the organic solvent having the SP value of 8.5 or more and 12 or less in the ink is 20% by mass or more and 60% by mass or less. 10. An ink flight process of applying an ink according to any one of claims 1 to 9 with at least one kind of stimulus selected from heat, pressure, and vibration to fly the recording ink to print an image. An image forming method characterized by the above. 10. An ink flight means for applying the ink according to any one of claims 1 to 9 with at least one kind of stimulus selected from heat, pressure, and vibration to fly the recording ink to print an image. An image forming apparatus characterized by the above.

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