JP6772776B2 - Ink, recording method, and recording device - Google Patents

Description

The present invention relates to inks, recording methods, and recording devices.

A method using titanium dioxide as the white color material of the white ink for inkjet is generally used. Further, an ink using hollow resin particles having a hollow inner layer as a white color material is also known.

The hollow resin particles exhibit whiteness by utilizing the difference in refractive index between the inner layer and the outer shell resin. For example, an ink composition containing hollow resin particles and at least one anti-transparency agent selected from hexylene glycol and trimethylolpropane has been proposed (see, for example, Patent Document 1).
Further, multimode inks in which the particle sizes of the hollow resin particles differ by at least 0.1 μm have been proposed (see, for example, Patent Document 2).

An object of the present invention is to provide an ink that can suppress a decrease in whiteness and maintain a degree of precipitation even when heated or when an organic solvent having a low SP value is used.

The ink of the present invention as a means for solving the above-mentioned problems is hollow containing a copolymer having a structural unit represented by the following structural formula (1) and a structural unit represented by the following structural formula (2). containing resin particles, and an organic solvent, and water, in the IR spectrum of the hollow resin particles, and the maximum value of the peak at 1,600cm ^-1 ± 10cm ^-1 and X, 1,730cm ^-1 ± 10cm ^-1 The peak ratio (Y / X) when the maximum value of the peak in is Y is 3.0 or more and 6.0 or less, and the mixed SP value of the organic solvent is 11.0 (cal / cm ³ ) ^{0. It is 5.5} or more and 15.5 (cal / cm ³ ) ^0.5 or less.

According to the present invention, it is possible to provide an ink that can suppress a decrease in whiteness and maintain a degree of precipitation even when heated or when an organic solvent having a low SP value is used.

FIG. 1 is a perspective explanatory view showing an example of an inkjet recording device. FIG. 2 is a perspective explanatory view showing an example of a main tank in an inkjet recording device.

(ink)
The ink of the present invention contains hollow resin particles containing a copolymer having a structural unit represented by the following structural formula (1) and a structural unit represented by the following structural formula (2), an organic solvent, and water. containing, in the IR spectrum of the hollow resin particles, the maximum value of the peak at 1,600cm ^-1 ± 10cm ^-1 and X, when the maximum value of the peak at 1,730cm ^-1 ± 10cm ^-1 and the Y The peak ratio (Y / X) of is 3.0 or more and 6.0 or less, and the mixed SP value of the organic solvent is 11.0 (cal / cm ³ ) ^0.5 or more and 15.5 (cal / cm). ³ ) It is ^0.5 or less, and preferably contains a wax, and further contains other coloring materials, resins, and additives as necessary.
The ink of the present invention is an ink using conventional hollow resin particles, and when heated or when the ink contains an organic solvent having a low SP value, the resin dissolves and the hollow resin particles are crushed. It is based on the finding that there is a problem that the brightness L ^* is lowered and the whiteness is lowered, and there is a problem that only the hollow resin particles float in the ink due to the collapse of the hollow resin particles.

<Hollow resin particles>
The hollow resin particles include a copolymer having a structural unit represented by the structural formula (1) and a structural unit represented by the structural formula (2).

The hollow resin particles are white and have excellent opacity due to light scattering due to the difference in refractive index between the air layer inside the particles after drying and the polymer layer of the shell.
When the copolymer contains the structural unit represented by the structural formula (1), the brightness L ^* of the ink itself can be improved. Further, since the copolymer contains the structural unit represented by the structural formula (2), the strength of the hollow resin particles can be improved and the hollow resin particles are suppressed from being crushed, so that the hunter whiteness Can be improved.

Wherein in the IR spectrum of the hollow resin particles, 1,600cm ^-1 the maximum value of the peak at ± 10 cm ^-1 and X, the peak ratio when the maximum value of the peak at 1,730cm ^-1 ± 10cm ^-1 was Y ( Y / X) is 3.0 or more and 6.0 or less, and preferably 3.0 or more and 5.5 or less.
The peak ratio (Y / X) is the ratio of the structural unit represented by the structural formula (1) and the structural unit represented by the structural formula (2) in the hollow resin particles (the structural formula (2)). It means the structural unit represented by (the structural unit represented by the structural formula (1)).
This is because infrared absorption at 1,600 cm ^-1 is caused by C = C expansion and contraction vibration of the aromatic ring contained in the structural unit represented by the structural formula (1), and 1,730 cm ^-1. This is because the infrared absorption in the above is caused by the expansion and contraction vibration of the carbonyl group C = O contained in the structural unit represented by the structural formula (2).

When the peak ratio (Y / X) is 3.0 or more, the proportion of the structural unit represented by the structural formula (2) in the copolymer of the hollow resin particles becomes high, and the hollow resin particles Since the strength of the hunter is increased, it is possible to suppress a decrease in hunter whiteness caused by melting the resin of the hollow resin particles by energy such as heat. When the peak ratio (Y / X) is 6.0 or less, the structural unit represented by the structural formula (1) and the structure represented by the structural formula (2) in the copolymer. The unit can be balanced, the hollow resin particles can be suppressed from being crushed, and the hunter whiteness can be improved. In addition, the problem that only the hollow resin particles float in the ink can be improved, and the degree of sedimentation can be maintained.

The ratio of the structural unit represented by the structural formula (1) and the structural unit represented by the structural formula (2) in the hollow resin particles is the structural unit represented by the structural formula (1) and the structural unit represented by the structural formula (1) in the ink. It is almost the same as the ratio of the structural units represented by the structural formula (2).
The ratio of the structural unit represented by the structural formula (1) and the structural unit represented by the structural formula (2) in the ink (the structural unit represented by the structural formula (2) / the structural formula (1)). The structural unit (represented by) is preferably 3.0 or more and 6.0 or less.

As the hollow resin particles, those synthesized as appropriate may be used, or commercially available products may be used.
The method for synthesizing the hollow resin particles is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a vinyl monomer, a surfactant, a polymerization initiator, and an aqueous dispersion medium are heated in a nitrogen atmosphere. The so-called emulsion polymerization method, in which a hollow resin particle emulsion is formed by stirring while stirring, is preferable.

Examples of the vinyl monomer include nonionic monofunctional ethylene unsaturated monomer, bifunctional vinyl monomer, and trifunctional or higher functional vinyl monomer. These may be used alone or in combination of two or more.

Examples of the nonionic monofunctional ethylene unsaturated monomer include styrene, vinyltoluene, ethylene, vinyl acetate, vinyl chloride, vinylidene chloride, acrylonitrile, (meth) acrylamide, and (meth) acrylic acid ester. These may be used alone or in combination of two or more. Among these, (meth) acrylic acid ester is preferable.

Examples of the (meth) acrylic acid ester include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and benzyl (meth) acrylate. ) Acrylate, lauryl (meth) acrylate, oleyl (meth) acrylate, palmityl (meth) acrylate, stearyl (meth) acrylate and the like.

Examples of the bifunctional vinyl monomer include divinylbenzene, allyl (meth) acrylate, ethylene glycol di (meth) acrylate, 1,5-butanediol di (meth) acrylate, and diethylene glycol di (meth) acrylate. ..

Examples of the trifunctional or higher vinyl monomer include trimethylolpropane tri (meth) acrylate.

By copolymerizing the nonionic monofunctional ethylene unsaturated monomer with at least one of the bifunctional vinyl monomer and the trifunctional or higher vinyl monomer and highly cross-linking, not only the light scattering property but also the heat resistance Hollow resin particles having properties such as properties, solvent resistance, and solvent dispersibility can be obtained.

The surfactant may be any one that forms molecular aggregates such as micelles in water, and examples thereof include anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. Can be mentioned. These may be used alone or in combination of two or more.

As the polymerization initiator, a known compound that is soluble in water can be used, and examples thereof include hydrogen peroxide and potassium persulfate. These may be used alone or in combination of two or more.

Examples of the aqueous dispersion medium include water and water containing a hydrophilic organic solvent.

Examples of commercially available products of the hollow resin particles include ROPAQUE ULTRA E (peak ratio (Y / X) = 1.5) manufactured by Dow Chemical Co., Ltd., DUAL, OP-62; Cybinol series manufactured by Saiden Chemical Co., Ltd. Examples include the SX series manufactured by JSR Corporation. These may be used alone or in combination of two or more.

The hollow ratio of the hollow resin particles is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 20% or more and 80% or less, and more preferably 35% or more and 70% or less. When the hollow ratio is 20% or more, the hunter whiteness of the printed image can be improved, and when it is 80% or less, the particle size of the hollow resin particles can be kept small, so that the ink is contained. It is possible to suppress the sedimentation at.
Examples of the measurement of the hollow ratio include a method using a scanning electron microscope (SEM). The hollow ratio is a ratio of the volume when the outer diameter and the inner diameter (diameter of the hollow portion) of the hollow resin particles are approximated to a sphere, and can be expressed by the following formula (1).
Hollow ratio (%) = (internal volume of hollow resin particles / volume of hollow resin particles) × 100 ... Equation (1)
Internal volume of hollow resin particles = 4π / 3 × (inner diameter of hollow resin particles) ³
Volume of hollow resin particles = 4π / 3 × (outer diameter of hollow resin particles) ³

The 50% cumulative volume particle size of the hollow resin particles is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 400 nm or more and 600 nm or less. When the 50% cumulative volume particle size is 400 nm or more, the brightness can be ensured even for a recording medium such as woodfree paper. When the 50% cumulative volume particle size is 600 nm or less, the sedimentation degree and the discharge stability are excellent.
The 50% cumulative volume particle diameter can be measured using, for example, a particle size analyzer (device name: Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

The hollow resin particles have a hollow inner layer and a resin covering the outer layer, and the outer diameter of the particles is preferably 0.1 μm or more and 1 μm or less, and the inner diameter is 0.04 μm or more and 0.8 μm or less. preferable.
Examples of the particle size measurement include a method using a laser scattering / diffraction type particle size measuring device.

Since the inner layer of the hollow resin particles is hollow, the specific gravity of the ink as an ink is about 1, and it is difficult to settle with time like titanium dioxide.
The average thickness of the outer layer of the hollow resin particles is preferably 10% or more and 20% or less with respect to the total size of the hollow resin particles in order to avoid sedimentation with time.

The content of the hollow resin particles is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 3.0% by mass or more and 14.0% by mass or less with respect to the total amount of ink. More preferably, it is 0% by mass or more and 12.5% by mass or less. When the content is 5.0% by mass or more, the hunter whiteness can be ensured even for a recording medium such as woodfree paper. When the content is 12.5% by mass, the sedimentation degree and the discharge stability are excellent.

<Organic solvent>
In the organic solvent, the mixed SP value calculated from the solubility parameter (hereinafter referred to as SP value) of the organic solvent alone excluding water in the ink is 11.0 (cal / cm ³ ) ^0.5 or more 15. 5 (cal / cm ³ ) ^0.5 or less.
When the mixed SP value is 11.0 (cal / cm ³ ) ^0.5 or more, the difference between the hollow resin particles and the SP value of the outer shell resin becomes large, so that the organic solvent contained in the ink It is possible to prevent the outer shell resin of the hollow resin particles from being dissolved. When the mixed SP value is 15.5 (cal / cm ³ ) ^0.5 or less, the organic solvent easily volatilizes and good drying property can be obtained. Therefore, deterioration of fixability due to poor drying can be suppressed. it can.

The mixed SP value in the mixed solution of the organic solvent contained in the ink can be calculated from the following formula (2).
Mixed SP value (cal / cm ³ ) ^0.5 in the mixed solution of the organic solvent in the ink
= [SP value of organic solvent A x volume fraction of organic solvent A] + [SP value of organic solvent B x volume fraction of organic solvent B] + ... Equation (2)

The SP value is a numerical value indicating how easily each other dissolves. The SP value is represented by the attractive force between the molecules, that is, the square root of the cohesive energy density CED (Cohesive Energy Density). The CED is the amount of energy required to evaporate 1 mL of the product.

The SP value can be calculated by the Fedors method using the following equation (3).
SP value (solubility parameter) = (CED value) ^1/2 = (E / V) ^1/2 ... Equation (3)
In the above formula (3), when E is the molecular aggregation energy (cal / mol) and V is the molecular volume (cm ³ / mol), and the evaporation energy of the atomic group is Δei and the molar volume is Δvi, the following formula ( It is represented by 4) and the formula (5).
E = ΣΔei ・ ・ ・ Equation (4)
V = ΣΔvi ・ ・ ・ Equation (5)
Although there are various theories about the calculation method of the SP value, the Fedors method generally used in the present invention was used.

As the calculation method, the data of the evaporation energy Δei and the molar volume Δvi of each atomic group, the data described in "Basic Theory of Adhesion" (written by Minoru Imoto, published by Polymer Publishing Association, Chapter 5) can be used. it can.
In addition, for those for which -CF ₃ units etc. are not shown, R.M. F. Fedors, Polym. Eng. Sci. 14,147 (1974) can be referred to.
For reference, when converting the SP value represented by the above formula (3) to (J / cm ³ ) ^1/2 , 2.046 is converted to SI unit (J / m ³ ) ^1/2 . If you do, you can multiply by 2,046.

In the present invention, the organic solvent includes those that are functionally classified as penetrants, antifoaming agents, and the like. Further, in the present invention, only the organic solvent contained in an amount of 3% by mass or more based on the total amount of the ink is considered in the calculation of the SP value. When only one kind of organic solvent is used, the SP value of the one kind of organic solvent is used as the mixed SP value.

Examples of the organic solvent include ethers such as polyhydric alcohols, polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, sulfur-containing compounds and propylene carbonates. Examples include ethylene carbonate. These may be used alone or in combination of two or more.

Examples of the polyhydric alcohols include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, and 1,4-butanediol. 2,3-Butanediol, 3-Methyl-1,3-Butanediol, Triethylene glycol, Polyethylene glycol, Polypropylene glycol, Isoprene glycol, 1,2-Pentanediol, 1,3-Pentanediol, 1,4-Pentane Diol, 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 Examples thereof include -1,3-pentanediol and petriol.

Examples of the polyhydric alcohol alkyl ethers include ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether. Be done.

Examples of the polyhydric alcohol aryl ethers include ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.

Examples of the nitrogen-containing heterocyclic compound include 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, ε-caprolactam, and γ-. Butyrolactone and the like can be mentioned.

Examples of the amides include formamide, N-methylformamide, N, N-dimethylformamide, 3-methoxy-N, N-dimethylpropionamide, 3-butoxy-N, N-dimethylpropionamide and the like.

Examples of the amines include monoethanolamine, diethanolamine, triethylamine and the like.

Examples of the sulfur-containing compound include dimethyl sulfoxide, sulfolane, and thiodiethanol.

Among these, glycerin (SP value = 17.4 (cal / cm ³ ) ^0.5 , boiling point: 290 ° C.), 1,2-propanediol (SP value = 14.3 (cal / cm ³ ) ^0.5 ) , Boiling point: 178 ° C., 1,3-propanediol (SP value = 15.5 (cal / cm ³ ) ^0.5 , boiling point: 188 ° C.), 1,2-butanediol (SP value = 13.1 (SP value = 13.1) cal / cm ³ ) ^0.5 , boiling point: 194 ° C), 1,3-butanediol (SP value = 14.2 (cal / cm ³ ) ^0.5 , boiling point: 208 ° C), isoprene glycol (SP value = 12.1 (cal / cm ³ ) ^0.5 , boiling point: 203 ° C.), oxetane compound (SP value = 11.0 (cal / cm ³ ) ^0.5 , boiling point: 110 ° C.) are particularly preferable.
The organic solvent preferably has a boiling point of 250 ° C. or lower because it not only functions as a wetting agent but also has good drying properties.

Polyol compounds having 8 or more carbon atoms and glycol ether compounds are also preferably used. Specific examples of the polyol compound having 8 or more carbon atoms include 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol.
Specific examples of the glycol ether compound include polyvalent alcohol alkyls such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether. Ethers: Polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether can be mentioned.

A polyol compound having 8 or more carbon atoms and a glycol ether compound can improve the permeability of ink when paper is used as a recording medium.

The content of the organic solvent 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 60% by mass or less from the viewpoint of ink drying property and ejection reliability. More preferably, it is 20% by mass or more and 60% by mass or less.

<Water>
The water content in the ink is not particularly limited and may be appropriately selected depending on the intended purpose, but from the viewpoint of ink drying property and ejection reliability, it is preferably 10% by mass or more and 90% by mass or less, and 20% by mass. % To 60% by mass is more preferable.

<Color material>
The coloring material is not particularly limited, and pigments and dyes can be used.
As the pigment, an inorganic pigment or an organic pigment can be used. These may be used alone or in combination of two or more. Moreover, you may use a mixed crystal.
As the pigment, for example, black pigment, yellow pigment, magenta pigment, cyan pigment, white pigment, green pigment, orange pigment, glossy color pigment such as gold or silver, metallic pigment and the like can be used.
As inorganic pigments, in addition to titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red, and chrome yellow, carbon black produced by known methods such as contact method, furnace method, and thermal method. Can be used.
Examples of organic pigments include azo pigments and polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, and quinofuralone pigments). , Dye chelate (for example, basic dye type chelate, acidic dye type chelate, etc.), nitro pigment, nitroso pigment, aniline black and the like can be used. Among these pigments, those having a good affinity with a solvent are preferably used. In addition, resin hollow particles and inorganic hollow particles can also be used.
As a specific example of the pigment, for black, carbon black (CI pigment black 7) such as furnace black, lamp black, acetylene black, channel black, or copper, iron (CI pigment black 11) , Metals 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 Carmin 6B), 60: 1, 63: 1, 63: 2, 64: 1, 81, 83, 88, 101 (Magenta), 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 Greens 1, 4, 7, 8, 10, 17, 18, 36, etc.
The dye is not particularly limited, and acid dyes, direct dyes, reactive dyes, and basic dyes can be used, and one type may be used alone or two or more types may be used in combination.
As the dye, for example, 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. Dilekdo 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, more preferably 1% by mass or more and 10% by mass, from the viewpoint of improving image density, good fixability and ejection stability. It is as follows.

To disperse the pigment in the ink, a method of introducing a hydrophilic functional group into the pigment to obtain a self-dispersing pigment, a method of coating the surface of the pigment with a resin and dispersing it, a method of dispersing using a dispersant, And so on.
Examples of the method of introducing a hydrophilic functional group into a pigment to obtain a self-dispersing pigment include a self-dispersing pigment in which a functional group such as a sulfone group or a carboxyl group is added to a pigment (for example, carbon) so that the pigment can be dispersed in water. Can be used.
As a method of coating the surface of the pigment with a resin and dispersing it, a method in which the pigment is encapsulated in microcapsules and can be dispersed in water can be used. This can be rephrased as a resin coating pigment. In this case, it is not necessary that all the pigments to be blended in the ink are coated with the resin, and the uncoated pigments and the partially coated pigments are dispersed in the ink as long as the effects of the present invention are not impaired. You may be.
Examples of the method of dispersing using a dispersant include a method of dispersing using a known low molecular weight dispersant and a high molecular weight dispersant represented by a surfactant.
As the dispersant, for example, an anionic surfactant, a cationic surfactant, an amphoteric surfactant, a nonionic surfactant and the like can be used depending on the pigment.
RT-100 (nonionic surfactant) manufactured by Takemoto Oil & Fat Co., Ltd. and a naphthalene sulfonate Na formalin condensate can also be suitably used as a dispersant.
The dispersant may be used alone or in combination of two or more.

<Pigment dispersion>
It is possible to obtain ink by mixing a material such as water or an organic solvent with a coloring material. It is also possible to produce an ink by mixing a material such as water or an organic solvent with a pigment dispersion obtained by mixing a pigment and other water or a dispersant.
The pigment dispersion is obtained by dispersing water, a pigment, a pigment dispersant, and other components as necessary, and adjusting the particle size. It is preferable to use a disperser for dispersion.
The particle size of the pigment in the pigment dispersion is not particularly limited, but the maximum frequency is 20 nm or more in terms of the maximum number because the dispersion stability of the pigment is good and the image quality such as ejection stability and image density is also high. It is preferably 500 nm or less, more preferably 20 nm or more and 150 nm or less. The particle size of the pigment can be measured using a particle size analyzer (Nanotrack Wave-UT151, manufactured by Microtrac Bell Co., Ltd.).
The content of the pigment in the pigment dispersion is not particularly limited and may be appropriately selected depending on the intended purpose. However, from the viewpoint of obtaining good ejection stability and increasing the image density, 0.1 mass is used. % Or more and 50% by mass or less are preferable, and 0.1% by mass or more and 30% by mass or less are more preferable.
It is preferable that the pigment dispersion is degassed by filtering coarse particles with a filter, a centrifuge, or the like, if necessary.

<Resin>
The type of resin contained in the ink is not particularly limited and may be appropriately selected depending on the intended purpose. For example, urethane resin, polyester resin, acrylic resin, vinyl acetate resin, styrene resin, butadiene. Examples thereof include based resins, styrene-butadiene resins, vinyl chloride resins, acrylic styrene resins, and acrylic silicone resins. These may be used alone or in combination of two or more.
Among these, acrylic silicone-based resins and urethane resins are particularly preferable. Resin particles composed of these may be used.

The resin can be added to ink in the state of a resin emulsion dispersed using water as a dispersion medium and mixed with a material such as a coloring material or an organic solvent.
As the resin, a synthetic resin may be used, or a commercially available product may be used.

The glass transition temperature (Tg) of the resin is preferably −45 ° C. or higher and 0 ° C. or lower because it greatly contributes to the fixability of the ink when the drying step is performed after recording.
The glass transition temperature is raised by, for example, a differential scanning calorimetry (DSC) device (device name: DSC120U, manufactured by Seiko Instruments Co., Ltd.) at a measurement temperature of 30 ° C. to 300 ° C. and 2.5 ° C. per minute. It can be measured by speed.

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

The content of the resin is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 1% by mass or more and 10% by mass or less, and 1% by mass or more and 5% by mass or less, based on the total amount of ink. Is more preferable. When the content is 1% by mass or more, the fixability can be improved, and when the content is 10% by mass or less, the storage stability of the ink can be improved.

<Wax>
It is preferable that the ink contains wax in order to impart slipperiness to the image portion.
The wax is not particularly limited and may be appropriately selected depending on the intended purpose, but polyethylene wax and carnauba wax are preferable from the viewpoint of film formation property and slipperiness when the ink is applied to the image portion.
As the polyethylene wax, a commercially available product can be used. Examples of the commercially available product include Nopcote series manufactured by San Nopco, Nopco Maru series manufactured by San Nopco, Hitech series manufactured by Toho Chemical Industry Co., Ltd., and Big Chemie. -AQUACER series manufactured by Japan Co., Ltd. (for example, AQUACER-515) and the like can be mentioned. These may be used alone or in combination of two or more.
As the carnauba wax, a commercially available product can be used, and examples of the commercially available product include cellozole 524 and Torasoru CN manufactured by Chukyo Yushi Co., Ltd. These may be used alone or in combination of two or more.

The melting point of the wax is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 80 ° C. or higher and 140 ° C. or lower, and more preferably 100 ° C. or higher and 140 ° C. or lower. When the melting point is 80 ° C. or higher, the wax is less likely to be excessively melted or solidified even in a room temperature environment, and the storage stability of the ink can be maintained. Further, when the melting point is 140 ° C. or lower, the wax is sufficiently melted even in a room temperature environment, and slipperiness can be imparted to the image portion.

The volume average particle diameter of the wax is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.01 μm or more, and more preferably 0.01 μm or more and 0.1 μm or less. When the volume average particle diameter is 0.01 μm or more, the wax particles are likely to be oriented on the image surface, and slipperiness can be imparted to the image portion.
The volume average particle diameter can be measured using, for example, a particle size analyzer (device name: Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

The content of the wax is preferably 1% by mass or more and 10% by mass or less, and more preferably 1% by mass or more and 5% by mass or less with respect to the total amount of the ink. When the content is 1% by mass or more and 10% by mass or less, the slipperiness of the image portion becomes good.

The average particle size of the number of solids in the ink is not particularly limited and can be appropriately selected according to the purpose. However, from the viewpoint of improving image quality such as ejection stability and image density, the maximum number conversion is used. The maximum frequency is preferably 20 nm or more and 1,000 nm or less, and more preferably 400 nm or more and 600 nm or less.
The solid content of the ink includes particles of a coloring material, resin particles, wax and the like. The number average particle size can be measured using, for example, a particle size analyzer (device name: Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

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

<Surfactant>
As the surfactant, any of a silicone-based surfactant, a fluorine-based surfactant, an amphoteric surfactant, a nonionic surfactant, and an anionic surfactant can be used.
The silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. Among them, those that do not decompose even at high pH are preferable, and examples thereof include side chain modified polydimethylsiloxane, double-ended modified polydimethylsiloxane, one-ended modified polydimethylsiloxane, and side chain double-ended modified polydimethylsiloxane. Those having an oxyethylene group and a polyoxyethylene polyoxypropylene group are particularly preferable because they exhibit good properties as an aqueous surfactant. Further, as the silicone-based surfactant, a polyether-modified silicone-based surfactant can also be used, and examples thereof include a compound in which a polyalkylene oxide structure is introduced into the Si side chain of dimethylsiloxane.
As the fluorine-based surfactant, for example, a perfluoroalkyl sulfonic acid compound, a perfluoroalkyl carboxylic acid compound, a perfluoroalkyl phosphate ester compound, a perfluoroalkyl ethylene oxide adduct, and a perfluoroalkyl ether group are contained in a 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 sulfonic acid salt. Examples of the perfluoroalkylcarboxylic acid compound include perfluoroalkylcarboxylic acid and perfluoroalkylcarboxylic acid salt. The polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain includes a sulfate ester salt of a polyoxyalkylene ether polymer having a perfluoroalkyl ether group in the side chain and a perfluoroalkyl ether group in the side chain. Examples thereof include salts of polyoxyalkylene ether polymers. The counterions of the salts in these fluorine-based surfactants are Li, Na, K, NH ₄ , NH ₃ CH ₂ CH ₂ OH, NH ₂ (CH ₂ CH ₂ OH) ₂ , NH (CH ₂ CH ₂ OH). _3rd grade can be mentioned.
Examples of the amphoteric surfactant include laurylaminopropionate, lauryldimethylbetaine, stearyldimethylbetaine, and lauryldihydroxyethylbetaine.
Examples of the nonionic surfactant include polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ester, polyoxyethylene alkyl amine, polyoxyethylene alkyl amide, polyoxyethylene propylene block polymer, sorbitan fatty acid ester, and polyoxyethylene sorbitan. Examples thereof include ethylene oxide adducts of fatty acid esters and acetylene alcohols.
Examples of the anionic surfactant include polyoxyethylene alkyl ether acetate, dodecylbenzene sulfonate, lauryl salt, salt of polyoxyethylene alkyl ether sulfate, and the like.
These may be used alone or in combination of two or more.

The silicone-based surfactant is not particularly limited and may be appropriately selected depending on the intended purpose. For example, side chain-modified polydimethylsiloxane, double-ended modified polydimethylsiloxane, one-ended modified polydimethylsiloxane, side. Examples thereof include polydimethylsiloxane modified at both ends of the chain, and a polyether-modified silicone-based surfactant having a polyoxyethylene group and a polyoxyethylene polyoxypropylene group as modifying groups exhibits good properties as an aqueous surfactant, and is particularly effective. preferable.
As such a surfactant, an appropriately synthesized one 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 Chemical Co., Ltd., and the like.
The above-mentioned 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 dimethylpoly. Examples thereof include those introduced into the Si part side chain of siloxane.
[General formula (S-1)]
(However, in the general formula (S-1), m, n, a, and b represent integers. R and R'represent an alkyl group and an alkylene group.)
Commercially available products can be used as the above-mentioned polyether-modified silicone-based surfactant, 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.) and the like can be mentioned.

As the fluorine-based surfactant, a compound having 2 to 16 carbon atoms substituted with fluorine is preferable, and a compound having 4 to 16 carbon atoms substituted with fluorine is more preferable.
Examples of the fluorine-based surfactant include a perfluoroalkyl phosphate compound, a perfluoroalkylethylene oxide adduct, and a polyoxyalkylene ether polymer compound having a perfluoroalkyl ether group in the side chain.
Among these, polyoxyalkylene ether polymer compounds having a perfluoroalkyl ether group in the side chain are preferable because they have low foaming property, and are particularly fluorine-based compounds represented by the general formulas (F-1) and (F-2). Surfactants are preferred.
[General formula (F-1)]
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. It is an integer, or CpH _{2p + 1} and p is an integer of 1-19. a is an integer of 4 to 14.
Commercially available products may be used as the above-mentioned fluorine-based surfactant. Examples of this commercially available product 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.); Full Lard FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, FC-431 (all manufactured by Sumitomo 3M Co., Ltd.); Megafuck F-470, F -1405, F-474 (all manufactured by DIC Corporation); Zonyl TBS, FSP, FSA, FSN-100, FSN, FSO-100, FSO, FS-300, UR (all manufactured by DuPont) ); 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 Omniova), Unidyne DSN-403N (manufactured by Daikin Industries, Ltd.), etc. Among these, good print quality, especially color development, permeability to paper, wettability, etc. FS-300 manufactured by DuPont, FT-110, FT-250, FT-251, FT-400S, FT-150, FT-400SW, and Omniova manufactured by Neos Co., Ltd. from the viewpoint of significantly improving the leveling property. Polyfox PF-151N and Unidyne DSN-403N manufactured by Daikin Industries, Ltd. are particularly preferable.

The content of the surfactant in the ink is not particularly limited and may be appropriately selected depending on the intended purpose. However, from the viewpoint of excellent wettability and ejection stability and improvement in image quality, 0.001 mass is used. % Or more and 5% by mass or less are preferable, and 0.05% by mass or more and 5% by mass or less are more preferable.

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

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

<Rust inhibitor>
The rust preventive is not particularly limited, and examples thereof include acidic sulfites and sodium thiosulfate.

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

-Physical properties of ink-
The physical properties of the ink are not particularly limited, and viscosity, dynamic surface tension, pH and the like can be appropriately selected depending on the intended purpose.

[Hunter whiteness]
In the present invention, an image formed of the ink having a hunter whiteness of 20 or more is defined as white.
The hunter whiteness is preferably 60 or more, more preferably 60 or more and 90 or less. When the hunter whiteness is 60 or more, whiteness can be developed without being affected by the background color of the recording medium. When the hunter whiteness is 90 or less, the fixability and productivity can be further maintained.
The hunter whiteness can be determined as follows.
Using a recording device (device name: IPSiO GXe5500, manufactured by Ricoh Co., Ltd.), the ink is applied to a recording medium (trade name: Lumina Color Black 128 gsm, manufactured by Oji Ftex Co., Ltd.) with a recording resolution of 1,200 dpi x 1,200 dpi. And 2 mg / cm ² adhered and dried at 90 ° C. for 60 seconds to obtain an image formed. L ^* , a ^* , and b ^* of the obtained image were measured using a spectroscopic color densitometer (device name: X-Rite939, manufactured by X-Rite), and the hunter was calculated by the following formula (6). The whiteness can be calculated.
Hunter whiteness = 100-[(100-L ^* ) ² + (a ^{* 2} + b ^{* 2} )] ^0.5 ... Equation (6)

[Difference in sedimentation before and after standing]
The difference in sedimentation degree (MV value) before and after the ink of the present invention is left to stand for a long time is preferably -2 or more, and more preferably -2 or more and 0 or less. When the difference in the degree of sedimentation is -2 or more, it is possible to prevent the colorant from settling, which affects the ejection characteristics of the ink, even when the ink is left to stand for a long time. When the difference in sedimentation degree is 0 or less, it is possible to prevent only the hollow resin particles from floating in the ink.
The difference in the MV value is, for example, a sedimentation degree measuring device (device name: Turbiscan) for measuring the sedimentation degree of the ink before and after the ink is allowed to stand in an environment of 25 ° C. for 168 hours for 168 hours. It is measured by Classic MA2000, manufactured by Hideko Seiki Co., Ltd.), and can be calculated by subtracting the sedimentation degree before standing still from the obtained sedimentation degree of ink after standing for 168 hours.

[viscosity]
The viscosity of the ink at 25 ° C. is preferably 5 mPa · s or more and 30 mPa · s or less, preferably 5 mPa · s or more and 25 mPa · s, from the viewpoint of improving print density and character quality and obtaining good ejection stability. More preferably, it is s or less.
The viscosity can be measured by, for example, a rotary viscometer (device name: RE-80L, manufactured by Toki Sangyo Co., Ltd.). As the measurement conditions, it is possible to measure at 25 ° C. with a standard cone rotor (1 ° 34'x R24), a sample liquid volume of 1.2 mL, a rotation speed of 50 rpm, and 3 minutes.

[Dynamic surface tension]
The dynamic surface tension of the ink is 20 mN / m under the conditions of a bubble lifetime of 1,500 ms and 25 ° C. from the viewpoint that the ink is suitably leveled on the recording medium and the drying time of the ink is shortened. More than 35 mN / m or less is preferable.
The dynamic surface tension is a value measured at 25 ° C. by the maximum foam pressure method, and can be measured using, for example, a dynamic surface tension meter (manufactured by SITA Mestechnik). The "bubble lifetime" is the life of bubbles generated by the maximum bubble pressure method, and is also called "surface life", and is the maximum bubble pressure from the time when a new interface is formed in the probe tip of the dynamic surface tension meter. It means the time to become.

[PH]
The pH of the ink is preferably 7 to 12 and more preferably 8 to 11 in an environment of 25 ° C. from the viewpoint of preventing corrosion of the metal member in contact with the liquid.

(Pretreatment liquid)
The pretreatment liquid contains a coagulant, an organic solvent, and water, and may contain a surfactant, an antifoaming agent, a pH adjuster, an antiseptic / antifungal agent, an anticorrosive agent, and the like, if necessary.
As the organic solvent, surfactant, defoaming agent, pH adjuster, antiseptic / antifungal agent, and rust preventive, the same materials as those used for ink can be used, and other materials used for known treatment liquids can be used. ..
The type of flocculant is not particularly limited, and examples thereof include water-soluble cationic polymers, acids, and polyvalent metal salts.

(Post-treatment liquid)
The post-treatment liquid is not particularly limited as long as it is possible to form a transparent layer. The post-treatment liquid is obtained by selecting and mixing organic solvents, water, resins, surfactants, antifoaming agents, pH adjusters, antiseptic and antifungal agents, rust preventives and the like, if necessary. Further, the post-treatment liquid may be applied to the entire area of the recording area formed on the recording medium, or may be applied only to the area where the ink image is formed.

(recoding media)
The recording medium is not particularly limited, and plain paper, glossy paper, special paper, cloth, or the like can be used, but good image formation can be achieved even if a non-permeable base material is used.
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. , A base material having a water absorption amount of 10 mL / m2 or less from the start of contact to 30 msec 1/2 in the Bristow method.
As the impermeable substrate, for example, a plastic film such as a vinyl chloride resin film, a polyethylene terephthalate (PET) film, polypropylene, polyethylene, or a polycarbonate film can be preferably used.

(Recorded material)
The ink recording material of the present invention comprises an image formed by using the ink of the present invention on a recording medium.
It can be recorded by an inkjet recording device and an inkjet recording method to obtain a recorded material.

(Recording method and recording device)
The recording method of the present invention includes an ink applying step and a drying step, and if necessary, includes other steps.
The recording device of the present invention has an ink applying means and a drying means, and if necessary, has other means.
The recording method can be preferably carried out by the recording device.

<Ink applying process and ink applying means>
The ink application step is a step of ejecting the ink onto the recording medium to perform recording. In addition, a step of adhering various treatment liquids or the like to the recording medium may be included at least before and after applying the ink.
The ink applying means is a means for recording by ejecting the ink, various processing liquids, and the like onto the recording medium.
The ink applying step can be suitably carried out by the ink applying means.
The recording medium means a medium to which ink and various treatment liquids can adhere even temporarily.

The recording method and the recording device can be suitably used for various recording devices by an inkjet recording method, for example, a printer, a facsimile device, a copying device, a printer / fax / copier multifunction device, a three-dimensional modeling device, and the like.

The recording method and the recording device are not limited to those in which significant images such as characters and figures are visualized by ink. For example, those that form patterns such as geometric patterns and those that form a three-dimensional image are also included.

The recording device may include not only a head portion for ejecting ink, but also means related to feeding, transporting, and discharging paper of a recording medium, and other devices called pretreatment devices and posttreatment devices. ..

Unless otherwise specified, the recording device includes both a serial type device that moves the discharge head and a line type device that does not move the discharge head.
Further, as this recording device, not only a desktop type but also a wide recording device capable of printing on an A0 size recording medium, or, for example, continuous paper wound in a roll shape can be used as a recording medium. A continuous line printer is also included.

<Drying process and drying means>
The drying step is a step of drying the recording medium.
The drying means is a means for drying the recording medium.
The drying step can be preferably carried out by the drying means.
The drying means includes, for example, means for drying and heating the recording surface and the back surface of the recording medium. The drying means is not particularly limited, but for example, a warm air heater or an infrared heater can be used. The drying can be performed before recording, during recording, after recording, and the like.

The drying step and the drying means are not particularly limited, and the heating temperature, heating time, etc. can be appropriately selected according to the purpose.
The heating temperature is preferably 50 ° C. or higher and 170 ° C. or lower, more preferably 70 ° C. or higher and 150 ° C. or lower, further preferably 90 ° C. or higher and 150 ° C. or lower, and particularly preferably 120 ° C. or higher and 150 ° C. or lower. When the heating temperature is 50 ° C. or higher, the fixability can be improved. When the heating temperature is 170 ° C. or lower, the hunter whiteness can be improved.
The heating time is preferably 5 seconds or more and 90 seconds or less, more preferably 10 seconds or more and 60 seconds or less, and particularly preferably 10 seconds or more and 30 seconds or less. When the heating time is 5 seconds or more, the fixability can be improved. When the heating time is 90 seconds or less, the hunter whiteness can be improved.

An example of the recording device will be described with reference to FIGS. 1 and 2. FIG. 1 is a perspective explanatory view of the device. FIG. 2 is a perspective explanatory view of the main tank.
The image forming apparatus 400 as an example of the recording apparatus is a serial type image forming apparatus. A mechanical unit 420 is provided in the exterior 401 of the image forming apparatus 400. Each ink container 411 of the main tank 410 (410k, 410c, 410m, 410y) for each color of black (K), cyan (C), magenta (M), and yellow (Y) is, for example, an aluminum laminated film or the like. It is made of packaging members. The ink container 411 is housed in, for example, a plastic container case 414. The main tank 410 is used as an ink cartridge for each color.
A cartridge holder 404 is provided behind the opening when the cover 401c of the apparatus main body is opened. The main tank 410 is detachably attached to the cartridge holder 404. As a result, each ink ejection port 413 of the main tank 410 and the ejection head 434 for each color communicate with each other via the supply tube 436 for each color, and ink can be ejected from the ejection head 434 to the recording medium.

This recording device can include not only a portion that ejects ink, but also a device called a pretreatment device, a posttreatment device, and the like.
As one aspect of the pretreatment apparatus and the posttreatment apparatus, it has a pretreatment liquid and a posttreatment liquid as in the case of inks such as black (K), cyan (C), magenta (M), and yellow (Y). There is an embodiment in which a liquid accommodating portion and a liquid discharge head are added, and a pretreatment liquid or a posttreatment liquid is discharged by an inkjet recording method.
As another aspect of the pretreatment device and the posttreatment device, there is a mode in which a pretreatment device and a posttreatment device by, for example, a blade coating method, a roll coating method, and a spray coating method are provided other than the inkjet recording method.

The method of using the ink is not limited to the inkjet recording method, and can be widely used. In addition to the inkjet recording method, examples thereof include a blade coating method, a gravure coating method, a bar coating method, a roll coating method, a dip coating method, a curtain coating method, a slide coating method, a die coating method, and a spray coating method.

The use of the ink of the present invention is not particularly limited and may be appropriately selected depending on the intended purpose. For example, it can be applied to printed matter, paints, coating materials, base materials and the like. Further, it can be used not only as an ink to form two-dimensional characters and images, but also as a material for three-dimensional modeling for forming a three-dimensional three-dimensional image (three-dimensional model).
A known three-dimensional modeling device can be used for modeling the three-dimensional object, and the device is not particularly limited, but for example, an device provided with ink accommodating means, supply means, ejection means, drying means, and the like is used. be able to. The three-dimensional model includes a three-dimensional model obtained by overcoating with ink. In addition, a molded product obtained by processing a structure in which ink is applied on a base material such as a recording medium is also included. The molded product is, for example, a sheet-shaped or film-shaped recorded material or structure that has been subjected to molding processing such as heat stretching or punching, and is, for example, an automobile, an OA device, or electricity. -Suitably used for molding after decorating the surface of electronic devices, meters of cameras, panels of operation parts, etc.

Examples of the present invention will be described below, but the present invention is not limited to these examples.

In addition, "hollow resin particles and X and Y of ink", "50% cumulative volume particle diameter of hollow resin particles", and "mixed SP value of organic solvent" were measured as follows.

<Hollow resin particles and ink X and Y>
Hollow resin particles were prepared in the following, and more IR spectrum of the ink, the maximum value X of the peak at 1,600Cm ^-1, and 1,730cm the maximum value Y of the peak at ^-1, microscopic FT-IR measuring apparatus (apparatus Name: iN10MX / iZ10, manufactured by Thermo Fisher Scientific Co., Ltd.) and analysis software (trade name: OMNIC, manufactured by Thermo Fisher Scientific Co., Ltd.) were used for measurement.
The X and Y in the IR spectrum of the ink were substantially the same as the X and Y in the IR spectrum of the hollow resin particles.
Moreover, the peak ratio (Y / X) was calculated from the obtained X and Y.

<50% cumulative volume particle size of hollow resin particles>
The 50% cumulative volume particle size of the hollow resin particles produced below was measured using a particle size analyzer (device name: Nanotrack Wave-UT151, manufactured by Microtrack Bell Co., Ltd.).

<Mixed SP value of organic solvent>
The mixed SP value in the mixed solution of the organic solvent contained in the ink produced below was calculated from the following formula (2). However, when only one kind of organic solvent is used, the SP value of the one kind of organic solvent is used as the mixed SP value.
Mixed SP value (cal / cm ³ ) ^0.5 in the mixed solution of the organic solvent in the produced ink
= [SP value of organic solvent A x volume fraction of organic solvent A] + [SP value of organic solvent B x volume fraction of organic solvent B] + ... Equation (2)

(Production Example 1 of Hollow Resin Particles)
<Preparation of hollow resin particles B>
<< Synthesis of seed particle emulsion >>
Ion-exchanged water (726.0 g), methyl methacrylate (5.0 g), and methacrylic acid (0.1 g) are charged and stirred in a four-neck separable flask equipped with a stirrer, a thermometer, a cooler, and a dropping funnel. It was heated while warming. Then, when the internal temperature in the separable flask reached 70 ° C., a 10 mass% ammonium persulfate solution (1.0 g) was added, and the mixture was heated at 80 ° C. for 20 minutes. On the other hand, methyl methacrylate (141.0 g), methacrylic acid (94.9 g), sodium alkylbenzene sulfonate (5.0 g, trade name: Neogen SF-20, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) as an anionic emulsifier, and Ion-exchanged water (120.0 g) was emulsified with a homodisper to form a pre-emulsion, and then charged into a dropping funnel.
Next, while maintaining the internal temperature in the separable flask at 80 ° C., the pre-emulsion obtained above was uniformly added dropwise over 3 hours, and at the same time, 3% by mass of ammonium persulfate solution (10.0 g) was added. It was dropped uniformly over time. After completion of the dropping, the mixture was aged at 80 ° C. for 3 hours, cooled, and filtered through a 120-mesh filter cloth to obtain a seed particle emulsion.

<< Synthesis of hollow resin particles >>
Ion-exchanged water (188.2 g) was charged into a four-neck separable flask equipped with a stirrer, a thermometer, a cooler, and a dropping funnel, the seed particle emulsion (66.0 g) was added, and 80 while stirring. It was heated to ° C. On the other hand, petit acrylate (2.4 g), butyl methacrylate (1.1 g), methyl methacrylate (19.5 g), methacrylic acid (0.7 g), sodium alkylbenzene sulfonate (5.0 g, trade name: Neogen SF-20) , Daiichi Kogyo Seiyaku Co., Ltd.), and ion-exchanged water (55.3 g) were emulsified with homodisper to obtain pre-emulsion 1, and then charged into a dropping funnel. Then, while maintaining the internal temperature in the separable flask at 80 ° C., the pre-emulsion 1 obtained above was uniformly added dropwise over 30 minutes, and at the same time, a 10 mass% sodium persulfate solution (1.2 g) was added. The mixture was uniformly added dropwise over 30 minutes.

Next, styrene (75.0 g), sodium alkylbenzene sulfonate (5.0 g, trade name: Neogen SF-20, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and ion-exchanged water (51.8 g) are emulsified with homodisper. After the mixture was made into pre-emulsion 2, it was put into a dropping funnel. Then, while maintaining the internal temperature in the separable flask at 80 ° C., 1 hour after the dropping of the pre-emulsion 1 was completed, the pre-emulsion 2 obtained above was uniformly dropped over 60 minutes. At the same time, a 10 mass% sodium persulfate solution (3.5 g) was uniformly added dropwise over 60 minutes. After completion of dropping the pre-emulsion 2, 28% by mass of aqueous ammonia (7.5 g) was dropped, and the mixture was aged at 80 ° C. for 1 hour. After cooling, the mixture was filtered through a 120-mesh filter cloth to obtain hollow resin particles B.
The hollow resin particle B emulsion had a peak ratio (Y / X) = 3.0, 50% cumulative volume particle size: 600 nm, and solid content concentration: 20% by mass.

(Production Example 2 of Hollow Resin Particles)
<Preparation of hollow resin particles C>
Hollow resin particles C were obtained in the same manner as in Preparation Example 1 of the hollow resin particles, except that the amount of styrene was 39.0 g in the production example 1 of the hollow resin particles.
The hollow resin particle C emulsion had a peak ratio (Y / X) = 4.5, a 50% cumulative volume particle size: 600 nm, and a solid content concentration: 20.5% by mass.

(Production Example 3 of Hollow Resin Particles)
<Preparation of hollow resin particles D>
Hollow resin particles D were obtained in the same manner as in Preparation Example 1 of the hollow resin particles, except that the amount of styrene was 22.3 g in the production example 1 of the hollow resin particles.
The hollow resin particle D emulsion had a peak ratio (Y / X) = 6.0, a 50% cumulative volume particle size: 400 nm, and a solid content concentration: 26% by mass.

(Example 1)
3-Ethyl-3-hydroxymethyloxetane (manufactured by Tokyo Kasei Kogyo Co., Ltd., SP value = 11.0 (cal / cm ³ ) ^0.5 , boiling point: 110 ° C.) 33.0% by mass, silicone-based surfactant ( Product name: KF-640 (manufactured by Shin-Etsu Chemical Co., Ltd.) 1.0% by mass, as an antifoaming agent Product name: KF-353 (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5% by mass, as an antibacterial agent Name: Proxel LV (S) (manufactured by Nitto Denko Abyssia) 0.1% by mass, 2-amino-2-ethyl-1,3-propanediol (manufactured by Tokyo Kasei Kogyo Co., Ltd.) as a pH adjuster 0.4 Mass% and ion-exchanged water 54.0 mass% were stirred for 1 hour and mixed uniformly. Next, as a wax, 1.0% by mass of a polyethylene-based wax emulsion (trade name: AQUACER-515, manufactured by Big Chemie Japan Co., Ltd., melting point: 135 ° C., solid content concentration: 35% by mass) was added, and another 1 hour. It was stirred and mixed uniformly. Then, 10.0% by mass of the hollow resin particle D emulsion (peak ratio (Y / X) = 6.0, 50% cumulative volume particle size: 400 nm, solid content concentration: 26% by mass) was added for another 1 hour. It was stirred and mixed uniformly. This mixture was pressure-filtered with a polyvinylidene chloride membrane filter having an average pore size of 5 μm to remove coarse particles and dust to prepare the ink of Example 1. The content of each hollow resin particle in Table 1 is the amount as an emulsion.

(Examples 2 to 10 and Comparative Examples 1 to 4)
In Example 1, inks of Examples 2 to 10 and Comparative Examples 1 to 4 were prepared in the same manner as in Example 1 except that the composition was changed as shown in Tables 1, 2 and 4 below. did. The content of each resin emulsion in Tables 1, 2 and 4 is the amount as an emulsion.

(Example 11)
1,2-Propanediol (manufactured by Tokyo Kasei Kogyo Co., Ltd., SP value = 14.3 (cal / cm ³ ) ^0.5 , boiling point: 178 ° C.) 24.9% by mass, 1,2-butanediol (Tokyo Kasei) Made by Kogyo Co., Ltd., SP value = 13.1 (cal / cm ³ ) ^0.5 , boiling point: 194 ° C) 8.0% by mass, silicone-based surfactant (trade name: KF-640, Shin-Etsu Chemical Co., Ltd.) (Manufactured by) 1.0% by mass, as an antifoaming agent, trade name: KF-353 (manufactured by Shin-Etsu Chemical Co., Ltd.) 0.5% by mass, as an antibacterial agent, trade name: Proxel LV (S) (Nitto Denko Abyssia) ) 0.1% by mass, as a pH adjuster, 2-amino-2-ethyl-1,3-propanediol (manufactured by Tokyo Kasei Kogyo Co., Ltd.) 0.4% by mass, and ion-exchanged water 54.0% by mass. Was stirred for 1 hour and mixed uniformly. Next, as the resin, acrylic silicone resin emulsion (trade name: RKP-02, manufactured by Toyochem Co., Ltd., glass transition temperature (Tg) = -7 ° C., solid content concentration: 40% by mass) 0.1% by mass, and wax. As a whole, add 1.0% by mass of polyethylene wax emulsion (trade name: AQUACER-515, manufactured by Big Chemie Japan Co., Ltd., melting point: 135 ° C., solid content concentration: 35% by mass), and stir for another hour to make it uniform. Mixed. Then, 10.0% by mass of the hollow resin particle D emulsion (peak ratio (Y / X) = 6.0, 50% cumulative volume particle size: 400 nm, solid content concentration: 26% by mass) was added for another 1 hour. It was stirred and mixed uniformly. This mixture was pressure-filtered with a polyvinylidene chloride membrane filter having an average pore size of 5 μm to remove coarse particles and dust, and the ink of Example 11 was prepared.

(Examples 12 to 16)
In the example 11, the inks of Examples 12 to 16 were prepared in the same manner as in Example 11 except that the composition was changed as shown in Tables 2 and 3 below.

Next, the "difference in sedimentation degree", "hunter whiteness", and "fixation rate" were evaluated as follows. The results are shown in Tables 1 to 4 below.

<Difference in sedimentation before and after standing>
About 5 g of each of the obtained inks was placed in a glass tube having a capacity of 25 g (trade name: screw cap test tube, manufactured by AS ONE Corporation) and allowed to stand in an environment of 25 ° C. for 168 hours. The sedimentation degree of the ink before and after standing for 168 hours was measured by a sedimentation degree measuring device (device name: Turbiscan Classic MA2000, manufactured by Eiko Seiki Co., Ltd.). The difference in the degree of sedimentation was calculated by subtracting the degree of sedimentation before standing from the obtained degree of sedimentation of the ink after standing for 168 hours. The difference in sedimentation degree is -2 or more, which is a feasible level.

[Image formation]
Each of the produced inks is transferred to a recording medium (trade name: Lumina Color Black 127 gsm, manufactured by Oji F-Tex Co., Ltd.) by a recording device (device name: IPSiO GXe5500, manufactured by Ricoh Co., Ltd.) at 1,200 dpi x 1,200 dpi. An image sample was prepared by adhering at a recording resolution and an adhering amount of ² mg / cm ² and drying by heating at 90 ° C. for 60 seconds.
As the recording chart, a solid image of 3 cm square formed by a dot pattern was used.

<Hunter whiteness>
For the solid image of each image sample, L ^* , a ^* , and b ^* were measured using a spectroscopic color densitometer (device name: X-Rite939, manufactured by X-Rite), and the following formula (6) was used. , Hunter whiteness was calculated. A hunter whiteness of 60 or more is a feasible level.
Hunter whiteness = 100-[(100-L ^* ) ² + (a ^{* 2} + b ^{* 2} )] ^0.5 ... Equation (6)

<Retention rate>
A cotton cloth (trade name: TexTile Innovators, manufactured by SDL ATLAS Co., Ltd.) was attached to the solid image of each image sample, and the clock meter (manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.) with a load of 9 N was rubbed 5 times. The image forming portion before and after rubbing was measured with a spectroscopic color densitometer (trade name: X-Rite 939, manufactured by X-Rite). The value before rubbing was taken as 100%, and the value after rubbing was shown as a percentage. The larger the value, the better the fixing property of the image. The retention rate of 75% or more is a feasible level.

Details of the ink components in Tables 1 to 4 are as follows.

<Hollow resin particles>
-Hollow resin particle A emulsion (trade name: ROPAQUE ULTRA E, manufactured by Dow Chemical Co., Ltd., peak ratio (Y / X) = 1.5, 50% cumulative volume particle size: 400 nm, solid content concentration: 30% by mass)
-Hollow resin particle E emulsion (trade name: SX868, manufactured by JSR Corporation, peak ratio (Y / X) = 9.3, 50% cumulative volume particle size: 600 nm, solid content concentration: 20.3% by mass)
-Hollow resin particle F emulsion (trade name: X-212-902E, manufactured by Saiden Chemical Co., Ltd., peak ratio (Y / X) = 3.1, 50% cumulative volume particle size: 890 nm, solid content concentration: 28% by mass )

<Organic solvent>
-Glycerin (manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., SP value = 17.4 (cal / cm ³ ) ^0.5 , boiling point: 290 ° C)
・ 1,2-Propanediol (manufactured by Tokyo Chemical Industry Co., Ltd., SP value = 14.3 (cal / cm ³ ) ^0.5 , boiling point: 178 ° C.)
-1,2-Butanediol (manufactured by Tokyo Chemical Industry Co., Ltd., SP value = 13.1 (cal / cm ³ ) ^0.5 , boiling point: 194 ° C)
-3-Ethyl-3-hydroxymethyloxetane (manufactured by Tokyo Chemical Industry Co., Ltd., SP value = 11.0 (cal / cm ³ ) ^0.5 , boiling point: 110 ° C.)
3-Methoxy-N, N-dimethylpropionamide (manufactured by Idemitsu Kosan Co., Ltd., SP value = 9.2 (cal / cm ³ ) ^0.5 , boiling point: 216 ° C)

<Resin>
-Acrylic silicone resin emulsion (trade name: RKP-02, manufactured by Toyochem Co., Ltd., glass transition temperature (Tg) = -7 ° C, solid content concentration: 40% by mass)
-Urethane resin emulsion A (trade name: Superflex 420, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., glass transition temperature (Tg) = -10 ° C, solid content concentration: 38% by mass)
-Urethane resin emulsion B (trade name: Superflex 210, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., glass transition temperature (Tg) = 41 ° C., solid content concentration: 35% by mass)

<Wax>
-Polyethylene wax emulsion (trade name: AQUACER-515, manufactured by Big Chemie Japan Co., Ltd., melting point: 135 ° C., solid content concentration: 35% by mass)

<Surfactant>
-Silicone-based surfactant (trade name: KF-640, manufactured by Shin-Etsu Chemical Co., Ltd.)

<Defoamer>
・ Product name: KF-353, manufactured by Shin-Etsu Chemical Co., Ltd.

<Antibacterial agent>
・ Product name: Proxel LV (S) (manufactured by Nitto Denko Abyssia)

<pH adjuster>
-2-Amino-2-ethyl-1,3-propanediol (manufactured by Tokyo Chemical Industry Co., Ltd.)

[Evaluation of effects on heat drying]
<Test Examples 1 to 7>
In the formation of the image, the image was formed in the same manner as in the formation of the image, except that the ink of Example 5 was used and the heating conditions (heating temperature, heating time) after recording were changed as shown in Table 5 below. A sample was prepared. Using the prepared image sample, the "hunter whiteness" and the "fixation rate" were evaluated in the same manner as in Example 1. The results are shown in Table 5 below.

Examples of aspects of the present invention are as follows.
<1> Contains hollow resin particles containing a copolymer having a structural unit represented by the following structural formula (1) and a structural unit represented by the following structural formula (2), an organic solvent, and water. in the IR spectrum of the hollow resin particles, and the maximum value of the peak at 1,600cm ^-1 ± 10cm ^-1 and X, the peak ratio when the maximum value of the peak at 1,730cm ^-1 ± 10cm ^-1 and the Y (Y / X) is 3.0 or more and 6.0 or less, and the mixed SP value of the organic solvent is 11.0 (cal / cm ³ ) ^0.5 or more and 15.5 (cal / cm ³ ) ^0. It is an ink characterized by being ^5.5 or less.
<2> The ink according to <1>, wherein the 50% cumulative volume particle size of the hollow resin particles is 400 nm or more and 600 nm or less.
<3> The ink according to any one of <1> to <2>, wherein the content of the hollow resin particles is 5.0% by mass or more and 12.5% by mass or less.
<4> The ink according to any one of <1> to <3>, which further contains at least one of acrylic silicone resin particles and urethane resin particles.
<5> The ink according to <4>, wherein the glass transition temperature of at least one of the acrylic silicone resin particles and the urethane resin particles is 0 ° C. or lower.
<6> The ink according to any one of <4> to <5>, wherein the content of at least one of the acrylic silicone resin particles and the urethane resin particles is 1% by mass or more and 10% by mass or less. ..
<7> The ink according to any one of <1> to <6>, wherein the peak ratio (Y / X) is 3.0 or more and 5.5 or less.
<8> The ratio of the structural unit represented by the structural formula (1) and the structural unit represented by the structural formula (2) in the hollow resin particles (the structural unit represented by the structural formula (2) / the said. The ink according to any one of <1> to <7>, wherein the structural unit represented by the structural formula (1) is 3.0 or more and 6.0 or less.
<9> The organic solvent is at least one selected from glycerin, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, isoprene glycol, and an oxetane compound. The ink according to any one of <1> to <8>, which is a seed.
<10> The ink according to any one of <1> to <9>, wherein the organic solvent has a boiling point of 250 ° C. or lower.
<11> The ink according to any one of <1> to <10>, which further contains wax.
<12> The ink according to <11>, wherein the wax has a melting point of 80 ° C. or higher and 140 ° C. or lower.
<13> The ink according to any one of <11> to <12>, wherein the content of the wax is 1% by mass or more and 10% by mass or less.
<14> The ink according to any one of <1> to <13>, wherein the average particle size of the number of solids in the ink is 20 nm or more and 1,000 nm or less in terms of the maximum number.
<15> The ink according to any one of <1> to <14>, wherein the ink has a viscosity at 25 ° C. of 5 mPa · s or more and 30 mPa · s or less.
<16> The dynamic surface tension of the ink is described in any one of <1> to <15>, wherein the dynamic surface tension of the ink is 20 mN / m or more and 35 mN / m or less under the conditions of a bubble lifetime of 1,500 ms and 25 ° C. Ink.
<17> The hunter whiteness of an image formed by adhering the ink to a recording medium at an adhering amount of ² mg / cm ² and drying at 90 ° C. for 60 seconds is 60 or more, from <1> to <16. > Is the ink described in any of.
<18> The ink according to any one of <1> to <17>, wherein the difference in sedimentation degree before and after the ink is allowed to stand at 25 ° C. for 168 hours is -2 or more.
<19> The drying step includes an ink applying step of applying the ink according to any one of <1> to <18> to the recording medium and a drying step of drying the recording medium to which the ink is applied. This recording method is characterized in that the heating temperature is 70 ° C. or higher and 150 ° C. or lower, and the heating time is 10 seconds or longer and 60 seconds or lower.
<20> The drying step including an ink applying step of applying the ink according to any one of <1> to <18> to the recording medium and a drying step of drying the recording medium to which the ink is applied. The recording method is characterized in that the heating temperature in the above is 120 ° C. or higher and 150 ° C. or lower, and the heating time is 10 seconds or longer and 30 seconds or shorter.
<21> The drying means comprising an ink applying means for applying the ink according to any one of <1> to <18> to the recording medium and a drying means for drying the recording medium to which the ink is applied. The recording apparatus is characterized in that the heating temperature in the above is 70 ° C. or higher and 150 ° C. or lower, and the heating time is 10 seconds or longer and 60 seconds or lower.
<22> The drying means having an ink applying means for applying the ink according to any one of <1> to <18> to the recording medium and a drying means for drying the recording medium to which the ink is applied. The recording device is characterized in that the heating temperature in the means is 120 ° C. or higher and 150 ° C. or lower, and the heating time is 10 seconds or longer and 30 seconds or shorter.

The ink according to any one of <1> to <18>, the recording method according to any one of <19> to <20>, and the recording apparatus according to any one of <21> to <22>. According to the above, it is possible to solve the conventional problems and achieve the object of the present invention.

Japanese Unexamined Patent Publication No. 2014-28964 Japanese Patent No. 3747033

400 Image forming device 401 Image forming device exterior 401c Device body cover 404 Cartridge holder 410 Main tank 410k, 410c, 410m, 410y For each color of black (K), cyan (C), magenta (M), yellow (Y) Main tank 411 Ink storage unit 413 Ink discharge port 414 Storage container case 420 Mechanical unit 434 Discharge head 436 Supply tube

Claims (12)

It contains hollow resin particles containing a structural unit represented by the following structural formula (1) and a copolymer having a structural unit represented by the following structural formula (2), an organic solvent, and water.
Wherein in the IR spectrum of the hollow resin particles, 1,600cm ^-1 the maximum value of the peak at ± 10 cm ^-1 and X, the peak ratio when the maximum value of the peak at 1,730cm ^-1 ± 10cm ^-1 was Y ( Y / X) is 3.0 or more and 6.0 or less.
An ink characterized in that the mixed SP value of the organic solvent is 11.0 (cal / cm ³ ) ^0.5 or more and 15.5 (cal / cm ³ ) ^0.5 or less.
The ink according to claim 1, wherein the 50% cumulative volume particle size of the hollow resin particles is 400 nm or more and 600 nm or less. The ink according to any one of claims 1 to 2, wherein the content of the hollow resin particles is 5.0% by mass or more and 12.5% by mass or less. The ink according to any one of claims 1 to 3, further containing at least one of acrylic silicone resin particles and urethane resin particles. The ink according to claim 4, wherein the glass transition temperature of at least one of the acrylic silicone resin particles and the urethane resin particles is 0 ° C. or lower. The ink according to any one of claims 4 to 5, wherein the content of at least one of the acrylic silicone resin particles and the urethane resin particles is 1% by mass or more and 10% by mass or less. The hunter whiteness of an image formed by adhering the ink to a recording medium at an adhering amount of ² mg / cm ² and drying at 90 ° C. for 60 seconds according to any one of claims 1 to 6. Ink. The ink according to any one of claims 1 to 7, wherein the difference in sedimentation degree before and after allowing the ink to stand at 25 ° C. for 168 hours is -2 or more. An ink applying step of applying the ink according to any one of claims 1 to 8 to a recording medium,
Including a drying step of drying the recording medium to which the ink is applied.
A recording method characterized in that the heating temperature in the drying step is 70 ° C. or higher and 150 ° C. or lower, and the heating time is 10 seconds or longer and 60 seconds or shorter. An ink application step of applying an ink according to record medium to any one of claims 1 to 8,
Including a drying step of drying the recording medium to which the ink is applied.
A recording method characterized in that the heating temperature in the drying step is 120 ° C. or higher and 150 ° C. or lower, and the heating time is 10 seconds or longer and 30 seconds or shorter. An ink applying means for applying the ink according to any one of claims 1 to 8 to a recording medium,
It has a drying means for drying the recording medium to which the ink is applied.
A recording device characterized in that the heating temperature in the drying means is 70 ° C. or higher and 150 ° C. or lower, and the heating time is 10 seconds or longer and 60 seconds or lower. An ink applying means for applying ink according to record medium to any one of claims 1 to 8,
It has a drying means for drying the recording medium to which the ink is applied.
A recording device characterized in that the heating temperature in the drying means is 120 ° C. or higher and 150 ° C. or lower, and the heating time is 10 seconds or longer and 30 seconds or shorter.