WO2016039128A1 - 水性顔料分散体および水性インク - Google Patents
水性顔料分散体および水性インク Download PDFInfo
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- WO2016039128A1 WO2016039128A1 PCT/JP2015/073823 JP2015073823W WO2016039128A1 WO 2016039128 A1 WO2016039128 A1 WO 2016039128A1 JP 2015073823 W JP2015073823 W JP 2015073823W WO 2016039128 A1 WO2016039128 A1 WO 2016039128A1
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D11/00—Inks
- C09D11/02—Printing inks
- C09D11/14—Printing inks based on carbohydrates
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
- B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
- B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
- B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
- B41J2/01—Ink jet
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D11/00—Inks
- C09D11/02—Printing inks
- C09D11/03—Printing inks characterised by features other than the chemical nature of the binder
- C09D11/037—Printing inks characterised by features other than the chemical nature of the binder characterised by the pigment
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D11/00—Inks
- C09D11/02—Printing inks
- C09D11/10—Printing inks based on artificial resins
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D11/00—Inks
- C09D11/02—Printing inks
- C09D11/10—Printing inks based on artificial resins
- C09D11/102—Printing inks based on artificial resins containing macromolecular compounds obtained by reactions other than those only involving unsaturated carbon-to-carbon bonds
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D11/00—Inks
- C09D11/02—Printing inks
- C09D11/10—Printing inks based on artificial resins
- C09D11/106—Printing inks based on artificial resins containing macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- C09D11/107—Printing inks based on artificial resins containing macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds from unsaturated acids or derivatives thereof
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D11/00—Inks
- C09D11/30—Inkjet printing inks
- C09D11/32—Inkjet printing inks characterised by colouring agents
- C09D11/322—Pigment inks
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D11/00—Inks
- C09D11/30—Inkjet printing inks
- C09D11/32—Inkjet printing inks characterised by colouring agents
- C09D11/324—Inkjet printing inks characterised by colouring agents containing carbon black
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D11/00—Inks
- C09D11/30—Inkjet printing inks
- C09D11/38—Inkjet printing inks characterised by non-macromolecular additives other than solvents, pigments or dyes
-
- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D17/00—Pigment pastes, e.g. for mixing in paints
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
- C09D17/00—Pigment pastes, e.g. for mixing in paints
- C09D17/001—Pigment pastes, e.g. for mixing in paints in aqueous medium
Definitions
- the present invention relates to an aqueous pigment dispersion and aqueous ink containing bionanofiber and colloidal silica.
- water-based inks have been replaced by organic solvent-based inks in a wide range of fields because of their safety and low environmental impact.
- a water-based ink having no odor is indispensable.
- Water-based ink is applied to various printing methods such as offset printing method, gravure printing method, ink jet recording method, etc.
- the ink jet recording method is capable of on-demand printing. Many studies are currently under way to replace the toner method.
- bionanofiber is cellulose, chitin, and chitosan that are uniformly refined (nanofiber) at the nano level.
- it is a thixotropic viscosity for aqueous emulsion compositions for paint bonding and filling.
- Patent Document 5 there has been no known example of using it for the purpose of improving the optical density and scratch resistance of aqueous ink.
- a water-based ink for a writing instrument in which a modified cellulose nanofiber having a complicated structure is blended with a water-based ink to ensure excellent dispersion stability even with a colorant having a large specific gravity (see, for example, Patent Document 6).
- the modified cellulose nanofiber described in Patent Document 6 has a predetermined cellulose crystal structure, and after selectively oxidizing a hydroxyl group at a specific position in the cellulose molecule, it is subjected to a reduction reaction to obtain a carboxyl group content, an aldehyde group, and a ketone group. Therefore, it is necessary to prepare the total content in a certain range. For this reason, there existed a problem that it was expensive and the restriction
- Patent Document 4 contains at least one water-soluble organic solvent, water, at least one colorant, and at least one colloidal silica.
- the solubility parameter (SP Value) is 27.5 or less
- an ink-jet ink composition having a water-soluble organic solvent content of 40% by mass or more is disclosed. It is disclosed that an image with reduced image quality can be obtained.
- Patent Document 7 makes no mention of color developability (optical density).
- An object of the present invention is to provide an aqueous pigment dispersion and an aqueous ink that are excellent in optical density and scratch resistance of the obtained image.
- essential colloidal silica, bionanofiber having a specific average particle size and aspect ratio, and an anionic group-containing organic polymer compound that functions as a pigment dispersant or binder are essential components. It has been found that an aqueous pigment dispersion and an aqueous ink to solve the above problems.
- the present invention provides an aqueous pigment dispersion comprising at least a pigment, colloidal silica, a bio-nanofiber having an average diameter of 1 nm to 100 nm and an aspect ratio of 100 or more, and an anionic group-containing organic polymer compound. And an aqueous ink using the aqueous pigment dispersion described above.
- the present invention also provides a method for producing the above-described aqueous pigment dispersion and aqueous ink.
- an aqueous pigment dispersion excellent in optical density and scratch resistance of an image to be obtained and an aqueous ink using the aqueous pigment dispersion.
- the pigment used in the present invention is at least one pigment selected from known and commonly used organic pigments or inorganic pigments.
- the present invention can be applied to either an untreated pigment or a treated pigment.
- the treated pigment includes so-called self-dispersing pigments. This is because the self-dispersing pigment is produced by, for example, bonding (grafting) the hydrophilic group to the surface of the pigment by subjecting the pigment to physical treatment or chemical treatment.
- the self-dispersing pigment means a pigment that can be dispersed or dissolved in an aqueous medium without a dispersant.
- “dispersed or dissolved in an aqueous medium without a dispersant” means a state in which the surface is stably present in the aqueous medium due to the hydrophilic group on the surface without using a dispersant for dispersing the pigment.
- “stablely present in aqueous medium” means stable in water (25 ° C., solid content of 10% by mass) without a dispersant for 90 days (range of change in particle size of pigment is within +/ ⁇ 30%) It means that.
- the hydrophilic group includes —OM, —COOM, —SO 3 M, —SO 2 M, —SO 2 NH 2 , —RSO 2 M, —PO 3 HM, —PO 3 M 2 , —SO 2 NHCOR, —NH 3 and one or more hydrophilic groups selected from the group consisting of —NR 3 , that is, an anionic hydrophilic functional group.
- M in these formulas independently represents a hydrogen atom, an alkali metal, ammonium, a phenyl group which may have a substituent, or organic ammonium.
- R in these formulas independently of each other represents an alkyl group having 1 to 12 carbon atoms or an optionally substituted naphthyl group.
- Examples of the self-dispersing pigment include JP-A-8-3498, JP-T 2000-513396, JP-T 2008-524400, JP-T 2009-515007, JP-T 2010-537006, JP A pigment treated with a method described in Table 2012-500866 and the like can be used.
- As the raw material for the self-dispersing pigment both inorganic pigments and organic pigments can be used.
- the pigment used for these is not particularly limited, and those usually used as pigments for water-based inks can be used. Specifically, it can be dispersed in water or a water-soluble organic solvent, and a known inorganic pigment or organic pigment can be used. Examples of the inorganic pigment include carbon black produced by a known method such as iron oxide, a contact method, a furnace method, and a thermal method.
- Organic pigments include azo pigments (including azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments), polycyclic pigments (for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazines). Pigments, thioindigo pigments, isoindolinone pigments, quinofullerone pigments, etc.), dye chelates (for example, basic dye chelates, acidic dye chelates, etc.), nitro pigments, nitroso pigments, aniline black, and the like.
- azo pigments including azo lakes, insoluble azo pigments, condensed azo pigments, chelate azo pigments
- polycyclic pigments for example, phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazines.
- carbon black No. manufactured by Mitsubishi Chemical Corporation. 2300, no. 2200B, no. 900, no. 960, No. 980, no. 33, no. 40, No, 45, No. 45L, no. 52, HCF88, MA7, MA8, MA100, etc. are Raven 5750, Raven 5250, Raven 5000, Raven 3500, Raven 1255, Raven 700, etc. made by Columbia, and Regal 400R, Regal 330R, Regal 660R, Mull 660R, Mogul made by Cabot. Monarch 800, Monarch 880, Monarch 900, Monarch 1000, Monarch 1100, Monarch 1300, Monarch 1400, etc.
- pigments used in yellow ink include C.I. I. Pigment Yellow 1, 2, 12, 13, 14, 16, 17, 73, 74, 75, 83, 93, 95, 97, 98, 109, 110, 114, 120, 128, 129, 138, 150, 151, 154, 155, 174, 180, 185 and the like.
- pigments used in magenta ink include C.I. I. Pigment Red 5, 7, 12, 48 (Ca), 48 (Mn), 57 (Ca), 57: 1, 112, 122, 123, 146, 168, 176, 184, 185, 202, 209, etc. It is done.
- pigments used for cyan ink include C.I. I. Pigment blue 1, 2, 3, 15, 15: 3, 15: 4, 16, 22, 60, 63, 66, and the like.
- a commercially available product may be used.
- commercially available products include “CAB-O-JET200”, “CAB-O-JET250C”, “CAB-O-JET260M”, “CAB-O-JET270Y”, “CAB-” manufactured by Cabot Specialty Chemicals.
- a pigment dispersion in which a self-dispersing pigment is dispersed in an aqueous medium can be used.
- SENSIJET Black SDP1000 “SENSIJET Black SDP2000”, “Sensijet Ultra Yellow PY74”, “Sensijet Ultra Yellow PY74”, “Sensijet Ultra Sr1000” manufactured by Sensitive Colors, Inc. Ultra K ";
- These self-dispersing pigments may be used alone or in combination of two or more.
- the pigment content is preferably 0.5 to 30%, more preferably 1.0 to 12%, based on the total amount of water-based ink.
- the content is most preferably 3% or more and 12% or less. If the content is less than 3%, the printing density on plain paper cannot be secured, and if the content exceeds 12%, the discharge stability of the water-based ink from the inkjet head deteriorates due to an increase in ink viscosity or the like. It is.
- the particle size of the pigment is preferably 1 ⁇ m or less, more preferably a pigment composed of particles of 10 nm to 150 nm, and still more preferably a pigment composed of particles of 50 nm to 120 nm.
- colloidal silica used in the present invention is also referred to as colloidal silica or colloidal silicic acid.
- colloidal silica In water, it refers to a colloidal suspension of silicon oxide having Si—OH groups on its surface by hydration, and is formed when hydrochloric acid is added to an aqueous solution of sodium silicate.
- sol-gel method, etc. which are dispersed in non-aqueous solutions and fine powders made by the gas phase method, and the particle size is from several nm to several ⁇ m. A variety of things.
- the average particle size is preferably about 1 to 200 nm.
- the composition of the particles is indeterminate, and some particles are polymerized by forming siloxane bonds (—Si—O—, —Si—O—Si—).
- the particle surface is porous and is generally negatively charged in water.
- the average particle size can be measured by a laser diffraction scattering method or as an average particle size of each of 100 particles existing within a certain area from an electron micrograph of particles dispersed until the primary particle size can be determined. it can.
- desired rheological properties can be obtained by adding colloidal silica.
- Non-spherical colloidal silica is a general colloidal silica in which spherical or nearly spherical particles are present independently without being linked, whereas chain particles, in which small silica particles are elongated and connected, Colloidal silica having a three-dimensional network structure or a shape in which a plurality of spherical primary particles are connected.
- the colloidal silica used in the present invention is not particularly limited, and a commercially available product or one produced by a known production method can be used.
- commercially available products include Snowtex XS, Snowtex OXS, Snowtex S, Snowtex ST, Snowtex OS, Snowtex 20, Snowtex 30, Snowtex 40, Snowtex O, Snowtex N, Snowtex C, Snotex AK, Snotex 50, Snotex O-40, Snotex CM, Snotex 20L, Snotex OL, Snotex XL, MP-2040, MP4540M, Snotex UP, Snotex OUP, Snotex PS-S, Snowtex PS-M (above, Nissan Chemical Industries, Ltd.), PL-1, PL-3L, PL-5, PL-7 (above, Fuso Chemical Industries, Ltd.), Cataloid S-20L, Cataloid S-20H, Cataloid S-3 L, Cataloid S-30H, Cataloid SI-30, Cataloid SI-40, Cataloid SI-50, Cataloid SI-350, Cataloid SI-45P
- the bionanofiber used in the present invention means cellulose or chitin / chitosan that is uniformly refined (nanofiberized) at the nano level. For this reason, it is sometimes referred to as biomass nanofiber as disclosed in JP2013-216766A.
- the bionanofiber used in the present invention is not particularly affected by impurities other than cellulose, chitin, and chitosan, but is preferably cellulose nanofiber or chitosan nanofiber.
- the cellulose nanofibers used in the present invention preferably have an average diameter (also referred to as fiber diameter) of 1 nm to 100 nm, more preferably 1 nm to 50 nm, still more preferably 3 nm to 30 nm, and more preferably about 20 nm. Even more preferably.
- the aspect ratio is preferably 100 or more, more preferably from 100 to 10,000, and even more preferably from 100 to 2000. This is because, within such a range, a sufficient effect can be obtained at low cost.
- These cellulose nanofibers can be used alone or in combination of two or more.
- the average diameter (short diameter) of the cellulose nanofiber of the present invention defines the average diameter and aspect ratio of the cellulose nanofiber in a dry state.
- “aspect ratio” means the ratio of average fiber length to average diameter in cellulose nanofibers (average fiber length / average diameter).
- the average diameter and aspect ratio of the dried state in the present invention can be measured by a scanning electron microscope (SEM) or a transmission electron microscope (TEM, with electron staining). For example, a dispersion liquid in which cellulose nanofibers are dispersed is cast on a substrate and observed with an SEM, and the diameter and length values of 20 or more fibers per image obtained are read, and at least three of them are read.
- the image of a non-overlapping area is obtained, and information on the diameter and length of 100 fibers is obtained even if there are at least 30.
- the average diameter can be calculated from the obtained fiber diameter data, and the average fiber length can be calculated from the length data.
- the aspect ratio in the dry state of the present invention may be calculated by a method other than the above as long as the value does not change.
- the dry state is a state in which at least 99% by mass or more of the liquid has been removed from the cellulose nanofibers by a conventionally known method such as natural drying or freeze-drying under reduced pressure.
- Cellulose nanofibers used in the present invention can be expressed by an average diameter (short diameter) and an aspect ratio calculated based on the electron microscope observation results as described above, and commercially available electrical and optical particle diameter measurements. It can also be expressed as a hydrodynamic particle size using an apparatus.
- the hydrodynamic particle size of the cellulose nanofiber used in the present invention can be measured, for example, with a dynamic light scattering nanotrack particle size analyzer UPA-150EX (manufactured by Nikkiso Co., Ltd.).
- the hydrodynamic particle diameter of the cellulose nanofiber described in the present specification corresponds to the average particle diameter of a hydrodynamic equivalent sphere model formed when the cellulose nanofiber is dispersed in a solvent.
- the mode value is the maximum value of the particle size distribution.
- the 20% particle size is the particle size at the time when particles corresponding to 20% volume of the particle size distribution are fractionated
- the 80% particle size is the time when particles corresponding to 80% volume of the particle size distribution are fractionated.
- the mode (mode value) of hydrodynamic particle diameter at 0.1% by mass is preferably 100 nm to 800 nm, and preferably 200 nm to 700 nm. Is more preferably 250 nm to 650 nm.
- the distribution of the hydrodynamic particle size is preferably such that the ratio of the 80% particle size to the 20% particle size, ie, the value of (80% particle size) / (20% particle size) is 10 or less. , 8 or less, more preferably 6 or less.
- the cellulose nanofiber used in the present invention has a specific surface area (ultrasonic dispersion treatment for 1 minute, sample refractive index: 1.56-0.00i, calculated from a particle size distribution measurement (volume-based particle size distribution) by a light scattering method,
- the dispersion medium refractive index (calculated as 1.333-0.00i) is preferably 800 cm 2 / cm 3 or more and 3000 cm 2 / cm 3 or less, more preferably 1000 cm 2 / cm 3 or more and 2800 cm 2 / cm 3 or less. it is more preferable, and more preferably not more than 1200 cm 2 / cm 3 or more 2600cm 2 / cm 3.
- This specific surface area is the total (cm 2 ) of the surface area of particles per unit volume (1 cm 3 ), but is a value calculated from the particle size distribution data. Usually does not match.
- the color developability (optical density) and scratch resistance of an image formed with the aqueous ink can be set to desired levels.
- the mechanism has not been fully verified, it is presumed as follows. Since the glucose unit constituting cellulose has a chair-type conformation, a hydroxyl group is conformed to the glucopyranose ring in the horizontal direction, and only C and H are arranged in the vertical method. The vertical direction is hydrophobic and the horizontal direction is hydrophilic. Nanofibrosis increases the surface area, further enhancing this trend.
- pigment particles formed by cellulose nanofibers and complexes with anionic group-containing organic polymer compounds described below lower the interfacial tension between pigment particles / anionic group-containing organic polymer compounds. They believe that they have achieved a high level of balance that is essential for stable pigment dispersion, such as controlling the charge on the surface of the pigment particles and imparting repulsive force that can overcome the van der Waals forces between the pigment particles. Therefore, even when printing on plain paper mixed with various paper components, the pigment particles can be fixed without penetrating unnecessarily into the paper that is the substrate to be printed. In printing, adjacent color inks do not mix and are excellent in scratch resistance.
- the content of cellulose nanofiber is preferably 0.001 to 3%, more preferably 0.01 to 2%, and more preferably 0.05 to 1% with respect to the total mass of the ink. More preferably, it is the range. This is because if the content is less than 0.001%, the optical density and scratch resistance cannot be ensured, and if the content exceeds 3%, the printability is impaired due to an increase in the viscosity of the ink.
- the cellulose nanofibers used in the present invention are not particularly limited, and commercially available products or those manufactured by a known manufacturing method can be used.
- the cellulose fiber-containing material is produced by defibration or refinement by grinding and / or beating with a refiner, a high-pressure homogenizer, a medium stirring mill, a stone mill, a grinder or the like.
- Japanese Patent Application Laid-Open No. 2005-42283 It can also be produced by a known method such as the method described in Japanese Patent Publication.
- it can also manufacture using microorganisms (for example, acetic acid bacteria (Acetobacter)).
- a commercially available product can be used.
- Cellulose fiber-containing materials are used for plants (for example, wood, bamboo, hemp, jute, kenaf, crop residue, cloth, pulp, recycled pulp, waste paper), animals (for example, ascidians), algae, microorganisms (for example, acetic acid bacteria (Acetobacter) )), And those originating from microbial products are known, any of which can be used in the present invention.
- a cellulose nanofiber derived from a plant or a microorganism is preferable, and a cellulose nanofiber derived from a plant is more preferable.
- the cellulose nanofibers used in the present invention need not be so-called modified cellulose nanofibers that have been subjected to any chemical modification as described in, for example, JP2013-181167A and JP2010-216021, for example.
- So-called unmodified cellulose nanofibers produced by the method described in Kaikai 2011-56456 and commercially available unmodified cellulose nanofibers can also be used.
- Commercially available products of unmodified cellulose nanofibers include the bio-nanofiber “BiNFi-s” series from Sugino Machine Co., Ltd., the “Cerish” series from Daicel Finechem Co., Ltd., and the “CNF” series from Chuetsu Pulp. These cellulose nanofibers can be used alone or in combination of two or more.
- the cellulose nanofibers used in the present invention can confirm the presence of a 62 ppm peak corresponding to the C6 position of the primary hydroxyl group of the glucose unit in the 13 C-NMR chart.
- the modified cellulose nanofiber for example, when a part of the hydroxyl group at the C6 position of each glucose unit in the cellulose molecule is converted to a carboxyl group by oxidation treatment or the like, the above-mentioned 62 ppm peak disappears, There is a peak of 178 ppm derived from the carboxyl group.
- the cellulose nanofibers used in the present invention are not subjected to modification treatment such as oxidation treatment. For this reason, it is possible that the hydroxyl group of cellulose is substituted by some carboxy groups by the process in the manufacture and purification process of cellulose nanofibers.
- the amount of the substituent does not usually exceed 0.1 mmol / g.
- the amount of carboxyl groups can be measured by the following method. After preparing 60 cm 3 of 0.5% by mass slurry (aqueous dispersion) of cellulose nanofiber and adding 0.1 mol / L hydrochloric acid aqueous solution to pH 2.5, 0.05 mol / L sodium hydroxide aqueous solution was added dropwise. Then, the electrical conductivity is measured until the pH reaches 11, and the amount can be calculated from the amount of sodium hydroxide (a) consumed in the weak acid neutralization stage where the change in electrical conductivity is slow, using the following formula.
- the thermal decomposition temperature of the cellulose nanofiber used in the present invention is usually about 250 to 280 ° C., although it varies depending on crystallinity, average polymerization degree, and the like.
- the thermal decomposition temperature in this specification is the temperature at which weight loss due to thermal decomposition starts when the temperature is increased from room temperature (temperature increase rate: 5 ° C./min) with a thermogravimetric / differential thermal analyzer (TG-DTA). Means. The temperature at which weight reduction starts was plotted on the vertical axis and the temperature plotted on the horizontal axis, and was defined as the temperature at the intersection of the tangent when the weight was greatly reduced and the tangent before the weight was reduced.
- the crystallinity (ratio of cellulose I type crystal structure) of the cellulose nanofibers used in the present invention is determined by X-ray diffraction.
- the crystallinity of cellulose type I can be determined from the X-ray diffraction results of Segal et al. (L. Segal, JJ Greely et al., Text. Res. J., 29,786, 1959) and Kamide et al. Kamide et al, Polymer J., 17,909,1985).
- ⁇ c is the crystallinity (%) of cellulose type I
- Cellulose nanofibers used in the present invention do not require chemical treatment such as oxidation treatment of cellulose nanofibers, so there is no need to improve resistance to radicals and alkalis over a long period of time, and cellulose I type crystallization It is not necessary to select cellulose having a high degree (crystallinity of about 65 to 85%). That is, the effect of the present invention can be exhibited with cellulose nanofibers starting from cellulose having a crystallinity of about 50 to 70% (for example, 55 to 65%) obtained from wood pulp.
- the crystal form of the cellulose nanofiber used in the present invention is not particularly limited.
- both I ⁇ type and I ⁇ type cellulose can be suitably used.
- Cellulose derived from higher plants such as cotton has many I ⁇ type crystal components, but bacterial cellulose has many I ⁇ type crystal components. It can be appropriately selected from an economic viewpoint.
- the chitosan nanofibers used in the present invention have an average diameter (also referred to as fiber diameter) of preferably 1 nm to 100 nm, more preferably 1 nm to 50 nm, still more preferably 3 nm to 30 nm, and more preferably about 20 nm. Even more preferably.
- the aspect ratio is preferably 100 or more, more preferably from 100 to 10,000, and even more preferably from 100 to 2000. This is because, within such a range, a sufficient effect can be obtained at low cost.
- These chitosan nanofibers can be used alone, or two or more kinds can be mixed and used together with the above-mentioned cellulose nanofiber.
- the average fiber length and average diameter of the chitosan nanofiber of the present invention can be defined and calculated in the same manner as the average diameter and aspect ratio of the cellulose nanofiber.
- the chitosan nanofibers used in the present invention preferably have a hydrodynamic particle diameter mode (mode value) of 0.1 nm% (solvent: water) of 100 nm to 800 nm, preferably 200 nm to 700 nm. Is more preferably 250 nm to 650 nm.
- the distribution of the hydrodynamic particle size is preferably such that the ratio of the 80% particle size to the 20% particle size, ie, the value of (80% particle size) / (20% particle size) is 10 or less. , 8 or less, more preferably 6 or less.
- the chitosan nanofiber used in the present invention has a specific surface area (ultrasonic dispersion treatment 1 minute, sample refractive index: 1.56-0.00i, calculated from particle size distribution measurement (volume-based particle size distribution) by a light scattering method,
- the dispersion medium refractive index (calculated as 1.333-0.00i) is preferably 800 cm 2 / cm 3 or more and 3000 cm 2 / cm 3 or less, more preferably 1000 cm 2 / cm 3 or more and 2800 cm 2 / cm 3 or less. it is more preferable, and more preferably not more than 1200 cm 2 / cm 3 or more 2600cm 2 / cm 3.
- This specific surface area is the total (cm 2 ) of the surface area of particles per unit volume (1 cm 3 ), but is a value calculated from the particle size distribution data. Usually does not match.
- Chitosan is an amino polysaccharide obtained by deacetylation of chitin ( ⁇ -1,4-poly-N-acetyl-D-glucosamine) extracted from crabs and shrimp shells, and has a hydroxyl group at the C2-position of cellulose. Is replaced with an amino group. Conversion of chitin to chitosan (deacetylation reaction) does not proceed completely, and some of the sugar chains often contain N-acetylglucosamine, and more than 70% of glucosamine residues are deacetylated. Generally called chitosan. Thus, the quality of chitosan is indicated by the deacetylation rate (sometimes expressed as% DA) measured by NMR spectroscopy, infrared absorption spectroscopy (IR), colloid titration method, and the like.
- deacetylation rate sometimes expressed as% DA
- the glucose unit constituting chitosan has a chair-type conformation, a hydroxyl group is conformed to the glucopyranose ring in the horizontal direction, and only C and H are arranged in the vertical method.
- the vertical direction of chitosan is hydrophobic and the horizontal direction is hydrophilic. Nanofibrosis increases the surface area, further enhancing this trend. For this reason, in aqueous inks, pigment particles formed by chitosan nanofibers and composites with anionic group-containing organic polymer compounds described below lower the interfacial tension between pigment particles / anionic group-containing organic polymer compounds.
- chitosan nanofibers tend to be more hydrophilic and cationic than cellulose nanofibers, they tend to exhibit more desirable physical properties in highly polar magenta and yellow pigment dispersions.
- the pigment particles can be fixed without penetrating unnecessarily into the paper that is the substrate to be printed.
- adjacent color inks do not mix and are excellent in scratch resistance.
- water-based ink especially for inkjet, it is preferably 0.001 to 3%, more preferably 0.01 to 2%, and further preferably 0.05 to 1% with respect to the total mass of the ink. . This is because if the content is less than 0.001%, the optical density and scratch resistance cannot be ensured, and if the content exceeds 3%, the printability is impaired due to an increase in the viscosity of the ink.
- the chitosan nanofibers used in the present invention are not particularly limited, and commercially available products or those manufactured by a known manufacturing method can be used.
- Chitosan which is a raw material for chitosan nanofibers, is manufactured and sold by many companies all over the world, and it is known that products having the same structure can be purified from microbial cells other than commercially available products.
- the deacetylation rate of chitosan is not particularly limited, and an optimal one may be appropriately selected depending on the application. It is preferable to use purified chitosan that has been deproteinized and decalcified after chitin deacetylation treatment of crustaceans such as crabs and shrimps.
- Chitosan nanofibers are manufactured by defibrating or refining these chitosans by grinding and / or beating them with a refiner, high-pressure homogenizer, medium stirring mill, stone mill, grinder or the like. It can also be produced by a known method such as the method described in the publication.
- the chitosan nanofiber used in the present invention may be a commercially available product.
- Examples of commercially available chitosan nanofibers include bionanofiber “BiNFi-s” chitosan from Sugino Machine Co., Ltd. These chitosan nanofibers can be used alone, or two or more kinds can be mixed and used together with the above-mentioned cellulose nanofiber.
- the ratio of the said pigment used by this invention, the said colloidal silica, and the said bionanofiber may become a specific range.
- an aqueous medium such as a water-soluble solvent and / or water is used as the solvent. These may be used alone or as a mixed solvent composed of water and a water-soluble solvent.
- water-soluble solvent examples include ketones such as acetone, methyl ethyl ketone, methyl butyl ketone, and methyl isobutyl ketone; methanol, ethanol, 2-propanol, 2-methyl-1-propanol, 1-butanol, 2-methoxyethanol, Alcohols such as tetrahydrofuran; ethers such as 1,4-dioxane and 1,2-dimethoxyethane; amides such as dimethylformamide and N-methylpyrrolidone, and particularly ketones having 3 to 6 carbon atoms And a compound selected from the group consisting of alcohols having 1 to 5 carbon atoms.
- ketones such as acetone, methyl ethyl ketone, methyl butyl ketone, and methyl isobutyl ketone
- methanol ethanol, 2-propanol, 2-methyl-1-propanol, 1-butanol, 2-methoxyethanol
- Alcohols such as t
- a water-soluble organic solvent that can be dissolved in water can also be used.
- glycols such as ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, polyethylene glycol, and polypropylene glycol; diols such as butanediol, pentanediol, hexanediol, and diols similar to these; propylene laurate Glycol esters such as glycol; glycol ethers such as diethylene glycol monoethyl, diethylene glycol monobutyl, diethylene glycol monohexyl ether, propylene glycol ether, dipropylene glycol ether, and cellosolve containing triethylene glycol ether; methanol, ethanol, isopropyl alcohol , 1-propanol, 2-p Alcohols such as panol, 1-butanol, 2-butanol, butyl alcohol, pentyl alcohol, and alcohol
- water-soluble organic solvents such as lactams; glycerin and derivatives thereof, polyoxyethylene benzyl alcohol ether, and the like can be mentioned.
- These water-soluble organic solvents can be used alone or in combination.
- polyhydric alcohols such as glycols and diols having high boiling point and low volatility and high surface tension are preferable, and glycols such as diethylene glycol and triethylene glycol are particularly preferable.
- anionic group-containing organic polymer compound examples include an organic polymer compound containing a carboxyl group, a sulfonic acid group or a phosphoric acid group.
- anionic group-containing organic polymer compound examples include a polyvinyl resin having an anionic group, a polyester resin having an anionic group, an amino resin having an anionic group, and an acrylic resin having an anionic group.
- Epoxy resins having an anionic group Epoxy resins having an anionic group, polyurethane resins having an anionic group, polyether resins having an anionic group, polyamide resins having an anionic group, unsaturated polyester resins having an anionic group, anions And phenolic resins having an ionic group, silicone resins having an anionic group, fluorine-based polymer compounds having an anionic group, polysaccharide derivatives having an anionic group, and the like.
- acrylic resins having an anionic group and polyurethane resins having an anionic group are preferable because they are abundant in raw materials, easy to design, and excellent in pigment dispersion function.
- the acrylic resin having an anionic group is a copolymer of a monomer having an anionic group such as (meth) acrylic acid and another ethylenically unsaturated monomer copolymerizable therewith.
- the resin which consists of is mentioned.
- (meth) acrylic acid means a generic term for acrylic acid and methacrylic acid. In the case of various esters of (meth) acrylic acid, it is interpreted in the same manner as described above.
- the hydrophobicity of the copolymer is further increased in the same acid value comparison, and the adsorption of the copolymer onto the pigment surface can be made stronger.
- styrene ⁇ -methyl styrene, ⁇ -methyl styrene, 2,4-dimethyl styrene, ⁇ -ethyl styrene, ⁇ -butyl styrene, alkyl styrene such as ⁇ -hexyl styrene, 4-chlorostyrene, 3-chlorostyrene, Halogenated styrene such as 3-bromostyrene, styrene monomers such as 3-nitrostyrene, 4-methoxystyrene, vinyltoluene, benzyl (meth) acrylate, phenyl (meth) acrylate, phenylethyl (meth) acrylate, phenylpropylene Lu (meth) acrylate, phenoxyethyl (meth) acrylate, etc.
- a (meth) acrylic acid ester monomer having a benzene ring It is preferable to use a (meth) acrylic acid ester monomer having a benzene ring.
- a styrene monomer such as styrene, ⁇ -methylstyrene, tert-butylstyrene.
- the copolymer according to the acrylic resin having an anionic group in the present invention contains a polymerization unit of (meth) acrylic acid and a polymerization unit of another copolymerizable ethylenically unsaturated monomer as essential polymerization units. These copolymers may be used, and even those binary copolymers may be ternary or more terpolymers with other copolymerizable ethylenically unsaturated monomers.
- Examples of the ethylenically unsaturated monomer include methyl acrylate, methyl methacrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, sec-butyl acrylate, tert-butyl acrylate, 2-ethylbutyl acrylate, 1,3-dimethyl Acrylic esters such as butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, ethyl methacrylate, n-butyl methacrylate, 2-methylbutyl methacrylate, pentyl methacrylate, heptyl methacrylate, and nonyl methacrylate Acrylic esters; 3-ethoxypropyl acrylate, 3-ethoxybutyl acrylate, dimethylaminoethyl acrylate, -Acrylic acid ester derivatives and methacrylic acid
- the copolymer based on the acrylic resin having an anionic group used in the present invention is a linear copolymer having only a polymerization unit of a monoethylenically unsaturated monomer, it has various crosslinking properties. It may be a copolymer containing a partly cross-linked part obtained by copolymerizing an ethylenically unsaturated monomer having a very small amount.
- Examples of the ethylenically unsaturated monomer having such crosslinkability include glycidyl (meth) acrylate, divinylbenzene, ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, polyethylene glycol di ( Examples include poly (meth) acrylates of polyhydric alcohols such as (meth) acrylates, poly (oxyethyleneoxypropylene) glycol di (meth) acrylates, and tri (meth) acrylates of alkylene oxide adducts of glycerol.
- the reaction rate and the like of each monomer used is considered to be substantially the same, and the charging ratio of each monomer is regarded as the content ratio in terms of mass of the polymerization unit of each monomer.
- the copolymer relating to the acrylic resin having an anionic group in the present invention can be synthesized by various conventionally known reaction methods such as bulk polymerization, solution polymerization, suspension polymerization and emulsion polymerization. In this case, a known and usual polymerization initiator, chain transfer agent (polymerization degree adjusting agent), surfactant and antifoaming agent can be used in combination.
- the copolymer relating to the acrylic resin having an anionic group used in the present invention among the copolymers, for example, styrene- (meth) acrylic acid copolymer, styrene- (meth) acrylic acid.
- Styrene monomers such as ester- (meth) acrylic acid copolymers, (meth) acrylic acid ester- (meth) acrylic acid copolymers, and styrene-acrylic acid copolymers containing (meth) acrylic acid as a raw material monomer A polymer is mentioned.
- the “styrene-acrylic acid copolymer” is defined as “a copolymer containing a styrene monomer and (meth) acrylic acid as a raw material monomer” as described above.
- General-purpose monomers other than styrene monomers and (meth) acrylic acid may be copolymerized
- the styrene-acrylic acid copolymer is obtained by copolymerization of at least one of a styrene monomer, an acrylic acid monomer, and a methacrylic acid monomer, but it is preferable to use acrylic acid and methacrylic acid in combination.
- the reason is that the copolymerization at the time of resin synthesis is improved, the uniformity of the resin is improved, and as a result, the storage stability is improved, and a more finely divided pigment dispersion tends to be obtained. It is.
- the total during the copolymerization of the styrene monomer, the acrylic acid monomer, and the methacrylic acid monomer is preferably 95% by mass or more based on the total monomer components.
- a method for producing the styrene-acrylic acid copolymer a usual polymerization method can be adopted, and a method of performing a polymerization reaction in the presence of a polymerization catalyst such as solution polymerization, suspension polymerization, bulk polymerization, etc. can be mentioned. It is done.
- a polymerization catalyst such as solution polymerization, suspension polymerization, bulk polymerization, etc.
- the polymerization catalyst include 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobisisobutyronitrile, 1,1′-azobis (cyclohexane-1-carbonitrile), Examples thereof include benzoyl peroxide, dibutyl peroxide, and butyl peroxybenzoate.
- the amount used is preferably 0.1 to 10.0% by mass of the monomer component.
- the styrene-acrylic acid copolymer may be a random copolymer or a graft copolymer.
- a graft copolymer a copolymer of polystyrene or a nonionic monomer copolymerizable with styrene and styrene is used as a trunk or branch, and a copolymer of acrylic acid, methacrylic acid and other monomers including styrene is branched.
- the graft copolymer used as a trunk can be shown as the example.
- the styrene-acrylic acid copolymer may be a mixture of the graft copolymer and the random copolymer.
- the acrylic resin having an anionic group preferably has a weight average molecular weight in the range of 5,000 to 20,000.
- the weight average molecular weight is preferably in the range of 5000 to 20000, and more preferably in the range of 5000 to 18000. In particular, it is particularly preferably in the range of 5500 to 15000.
- the weight average molecular weight is a value measured by a GPC (gel permeation chromatography) method, and is a value converted to a molecular weight of polystyrene used as a standard substance.
- the anionic group-containing organic polymer compound used in the present invention is a styrene-acrylic acid copolymer, it has a carboxyl group derived from an acrylic acid monomer and a methacrylic acid monomer, and the acid value thereof is 50 to 220 (mgKOH / g), preferably 60 to 200 (mg KOH / g).
- the acid value is 220 (mg KOH / g) or less, pigment aggregation tends to be less likely to occur.
- the acid value here is a numerical value measured according to Japanese Industrial Standard “K0070: 1992. Test method for acid value, saponification value, ester value, iodine value, hydroxyl value and unsaponified product of chemical products” This is the amount (mg) of potassium hydroxide required to completely neutralize 1 g of resin.
- the acid value is too low, the pigment dispersion and storage stability are lowered, and when an aqueous pigment dispersion for inkjet recording described later is prepared, the printing stability is deteriorated. If the acid value is too high, the water resistance of the colored recording image is lowered, which is also not preferable.
- (meth) acrylic acid may be included and copolymerized so as to be within the range of the acid value.
- the polyurethane resin having an anionic group used in the present invention has a polyol and a polyisocyanate having an anionic group such as a carboxy group or a sulfonic acid group, and a general-purpose anionic group as required. And urethane resins obtained by reacting polyols and chain extenders that are not used.
- Examples of the polyol having a carboxy group used in the present invention include esters obtained by reacting polyhydric alcohols with polybasic acid anhydrides, 2,2-dimethylol lactic acid, 2,2-dimethylol propionic acid, 2, And dihydroxyalkanoic acids such as 2-dimethylolbutanoic acid and 2,2-dimethylolvaleric acid.
- Preferred compounds include 2,2-dimethylolpropionic acid and 2,2-dimethylolbutanoic acid. Among them, dimethylolpropionic acid or dimethylolbutanoic acid is easily available and preferable.
- polyol having a sulfonic acid group examples include dicarboxylic acids such as 5-sulfoisophthalic acid, sulfoterephthalic acid, 4-sulfophthalic acid, and 5 [4-sulfophenoxy] isophthalic acid, and salts thereof, and the low molecular weight.
- dicarboxylic acids such as 5-sulfoisophthalic acid, sulfoterephthalic acid, 4-sulfophthalic acid, and 5 [4-sulfophenoxy] isophthalic acid, and salts thereof, and the low molecular weight.
- the polyester polyol obtained by making a polyol react is mentioned.
- diisocyanate used in the present invention examples include aliphatic diisocyanate compounds such as hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, and 4,4-cyclohexylmethane.
- diisocyanate compounds such as hexamethylene diisocyanate and 2,2,4-trimethylhexamethylene diisocyanate, isophorone diisocyanate, hydrogenated xylylene diisocyanate, and 4,4-cyclohexylmethane.
- examples thereof include alicyclic diisocyanate compounds such as diisocyanate, aromatic aliphatic diisocyanate compounds such as xylylene diisocyanate and tetramethylxylene diisocyanate, aromatic diisocyanates such as toluylene diisocyanate and phenylmethane diisocyanate
- polyester polyol which does not have a general purpose anionic group
- polyester polyol, polyether polyol, polyhydroxy polycarbonate, polyhydroxy polyacetal, polyhydroxy polyacrylate, polyhydroxy polyester amide, and polyhydroxy polythioether are mentioned, for example.
- polyester polyol, polyether polyol and polyhydroxy polycarbonate are preferred.
- One of these polyols may be reacted, or several may be mixed and reacted.
- a low molecular weight diol may be used in combination as appropriate for the purpose of adjusting the film hardness of the printed matter. Examples include ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, and the like.
- Examples of the chain extender used in the present invention include ethylene glycol, propylene glycol, 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol, and 1,4-bis ( ⁇ -hydroxyethoxy) benzene.
- Diols such as 1,4-cyclohexanediol and xylylene glycol, ethylenediamine, propylenediamine, xylylenediamine, isophoronediamine, 4,4′-diaminodiphenylmethane, tolylenediamine, 4,4′-diaminodicyclohexylmethane, etc.
- One kind or two or more kinds of diamines can be used.
- the polyurethane resin is produced by reacting the polyol and the polyisocyanate, for example, in the absence of a solvent or in the presence of an organic solvent.
- the urethane resin having an anionic group formed by neutralization using the basic compound or the like is mixed with an aqueous medium to make it aqueous, and if necessary, mixed with a chain extender. It can be produced by reacting.
- the reaction between the polyol and the polyisocyanate is preferably performed, for example, when the equivalent ratio of the isocyanate group of the polyisocyanate to the hydroxyl group of the polyol is in the range of 0.8 to 2.5, preferably 0.9 to It is more preferable to carry out in the range of 1.5.
- the polyurethane resin having an anionic group preferably has a weight average molecular weight in the range of 5,000 to 500,000, more preferably 10,000 to 200,000. It is particularly preferable to use a material having a viscosity of 15,000 to 100,000.
- the weight average molecular weight is a value measured by a GPC (gel permeation chromatography) method, and is a value converted to a molecular weight of polystyrene used as a standard substance.
- the polyurethane resin preferably has an acid value in the range of 2 to 200 (mg KOH / g), and preferably in the range of 2 to 100 (mg KOH / g). This is preferable for improving the good water dispersion stability.
- the acid value here is a value measured in accordance with Japanese Industrial Standard “K 0070: 1992. Test method for acid value, saponification value, ester value, iodine value, hydroxyl value and unsaponified product of chemical products”. , The amount (mg) of potassium hydroxide required to completely neutralize 1 g of resin. If the acid value is too low, the pigment dispersion and storage stability may be lowered, and if the acid value is too high, the water resistance of the formed image may be lowered. In order to make the copolymer within the range of the acid value, a polyol having a carboxy group may be included and copolymerized so as to be within the range of the acid value.
- the acrylic resin having an anionic group and the polyurethane resin having an anionic group are preferably used after being neutralized with a basic compound.
- alkali metal hydroxides such as potassium and sodium
- carbonates of alkali metals such as potassium and sodium
- carbonates such as alkaline earth metals such as calcium and barium
- Inorganic basic compounds such as ammonium hydroxide, amino alcohols such as triethanolamine, N, N-dimethanolamine, N-aminoethylethanolamine, dimethylethanolamine, NN-butyldiethanolamine, morpholine, N
- organic basic compounds such as morpholines such as methylmorpholine and N-ethylmorpholine, and piperazine such as N- (2-hydroxyethyl) piperazine and piperazine hexahydrate.
- alkali metal hydroxides represented by potassium hydroxide, sodium hydroxide, and lithium hydroxide contribute to lowering the viscosity of the aqueous pigment dispersion, and in terms of ejection stability when used as an aqueous inkjet recording ink.
- potassium hydroxide is particularly preferable.
- the neutralization rate of the anionic group using these is not particularly limited, but is generally in the range of 80 to 120%.
- the neutralization rate is a numerical value indicating the percentage of the basic compound blended with respect to the amount required for neutralization of all carboxyl groups in the anionic group-containing organic polymer compound. Is calculated by the following formula.
- polysaccharide derivatives having an anionic group It is also preferable to add a polysaccharide derivative having an anionic group to the aqueous pigment dispersion in the present invention.
- the polysaccharide derivative having an anionic group is not particularly limited as long as it is a polyanionic polysaccharide.
- natural polysaccharides such as hyaluronic acid, alginic acid, pectin, polygalacturonic acid, carboxymethyl pullulan, carboxymethyl chitin, carboxymethyl chitosan, carboxymethyl mannan, carboxymethyl starch, carboxymethyl dextran, carboxyethyl cellulose
- carboxyalkyl polysaccharides such as carboxymethyl pullulan
- oxidized polysaccharides such as oxidized cellulose and oxidized starch
- polysaccharides containing sulfate groups such as chondroitin sulfate, dermatan sulfate, heparin and heparan sulfate.
- carboxymethyl cellulose and hyaluronic acid are preferable, and carboxymethyl cellulose is particularly preferable.
- the weight average molecular weight of the raw material polysaccharide is not particularly limited, but the viscosity tends to increase as the degree of polymerization increases, so it may be selected according to the purpose. For example, 50,000 to 1,000,000 is preferable, and 50,000 to 500,000 is more preferable.
- the polysaccharide derivative having an anionic group in the present invention preferably forms a salt with a cation.
- the cation that forms a salt with a polysaccharide derivative having an anionic group is not particularly limited, but protons and metal ions, specifically, metal ions such as sodium, potassium, lithium, calcium, and magnesium, and organic such as organic ammonium Examples include cations.
- carboxymethylcellulose sodium salt and carboxymethylcellulose ammonium salt are preferable because they are easily available and the intended effect can be obtained, and carboxymethylcellulose ammonium salt is particularly preferable because of its high viscosity reducing effect.
- these polysaccharide derivatives having an anionic group can be used alone or in combination of two or more.
- the degree of etherification also referred to as degree of substitution (DS)
- degree of neutralization of polysaccharide derivatives having an anionic group used in the present invention particularly sodium salts and ammonium salts of carboxymethyl cellulose are particularly limited.
- the viscosity of a 1% by mass aqueous solution measured with a B-type viscometer at a rotor rotational speed of 60 rpm and 25 ° C. is 300 to 7000 mPa ⁇ s, and preferably 500 to 5000 mPa ⁇ s. It is further preferable to prepare as follows.
- the “degree of etherification” is a numerical value indicating, in carboxymethyl cellulose, the average number of hydroxyl groups in which carboxymethyl groups are ether-bonded among three hydroxyl groups contained in anhydroglucose which is a constituent unit of cellulose. is there. Therefore, the value is theoretically a value between 0 and 3.
- the degree of etherification of the sodium salt or ammonium salt of carboxymethyl cellulose used in the present invention is preferably 0.5 to 2, more preferably 0.6 to 1.6, still more preferably 0.8 to 1.4. It is. This is because if the degree of etherification is 0.8 or more, it has salt resistance.
- the theoretical upper limit of the degree of etherification is 3; however, if it exceeds 2, stable production is difficult, and if it is less than 0.4, it is difficult to dissolve in an aqueous medium, resulting in poor practicality.
- the degree of etherification can be determined according to, for example, CMC Industrial Association analysis method (ashing method). Weigh precisely 1 g of carboxymethylcellulose, put it in a magnetic crucible, incinerate at 600 ° C., titrate sodium oxide produced by ashing with 0.05 mol / L sulfuric acid and phenolphthalein as an indicator, and titrate per gram of carboxymethylcellulose. AmL can be calculated and put into the following equation.
- the blending amount of the polysaccharide derivative having an anionic group is not particularly limited, and an appropriate amount is blended according to the purpose described above.
- the mass part of the polysaccharide derivative having an anionic group with respect to the mass part 1 of the cellulose crystal body Is preferably 5 or less, more preferably 3 or less, and most preferably 2 or less.
- carboxymethyl cellulose sodium and carboxymethyl cellulose ammonium can be used.
- the Serogen series sold by Daiichi Kogyo Seiyaku Co., Ltd. the CMC Daicel series sold by Daicel Finechem Co., Ltd.
- the Sunrose F series sold by Nippon Paper Chemicals Co., Ltd. etc.
- carboxymethyl cellulose ammonium examples include the DN series sold by Daicel Finechem Co., Ltd.
- the content (mass basis) of the anionic group-containing organic polymer compound used in the present invention is preferably 0.1 to 10% with respect to the total mass of the ink in the case of an aqueous pigment dispersion, particularly for inkjet. Further, it is preferably 0.3 to 5%, more preferably 0.5 to 2%. If the content is less than 0.1%, the scratch resistance cannot be ensured. If the content exceeds 10%, the printability is impaired due to an increase in the viscosity of the ink.
- the anionic group-containing organic polymer compound is mainly used for the purpose of dispersing a pigment, but since the compound is a polymer, it also functions as a binder.
- the method for producing the aqueous pigment dispersion of the present invention can be obtained by a known method without any particular limitation. That is, the bionanofiber and the like can be blended at an arbitrary timing regardless of before and after medialess dispersion described later.
- a method of preparing an aqueous pigment dispersion comprising at least a pigment of the present invention and bionanofiber, etc., by adding other additives as necessary, by medialess dispersion (2) A method of preparing a high-concentration aqueous dispersion (pigment paste) of a pigment in advance and preparing it by adding other additives as necessary, such as bionanofiber, at the same time as dilution with an aqueous medium, etc. Can be given.
- (1) Medialess dispersion of aqueous pigment dispersion specifically includes ultrasonic dispersion, high-speed disk impeller, colloid mill, roll mill, high-pressure homogenizer, nanomizer, and optimizer.
- An ultrasonic dispersion method is preferable in consideration of productivity and contamination (foreign matter contamination or contamination) due to media wear. The present invention will be described in detail below using an example using an ultrasonic dispersion method.
- the viscosity range at this time is preferably 0.1 to 100 mPa ⁇ s, more preferably 0.5 to 50 mPa ⁇ s, still more preferably 0.5 to 30 mPa ⁇ s, from the viewpoint of ensuring fluidity. 1.0 to 20 mPa ⁇ s is most preferable.
- the pigment concentration at this time is preferably 1 to 30% by mass, more preferably 1 to 25% by mass, still more preferably 3 to 20% by mass, and most preferably 5 to 20% by mass.
- the conditions of ultrasonic irradiation are not particularly limited, but it is preferably performed at an output of 100 to 3000 W and a frequency of 15 to 40 kHz, and more preferably at an output of 150 to 2000 W and a frequency of 15 to 30 kHz.
- the dispersion process by cavitation can be effectively performed, the number of coarse particles in the aqueous pigment dispersion is reduced, and the saturation of the colored coating obtained from the aqueous pigment dispersion itself ( (Texture) has been improved, smooth discharge can be obtained when ink-jet printing of aqueous ink using the aqueous pigment dispersion (good discharge stability), and there is no deterioration in product quality due to sedimentation of pigment particles.
- the erosion (corrosion) of the oscillation rod is remarkably reduced, and the equipment maintenance cost is reduced.
- the ultrasonic irradiation time may be sufficient to ensure that the pigment particles, bionanofibers and the like are substantially uniformly dispersed in the aqueous pigment dispersion.
- an electric energy of 5 to 100 W / g is applied to the mass of the pigment contained in the dispersion.
- the ultrasonic treatment can be performed for a longer time or can be stopped in a short time.
- the sonication time can be selected within a range that does not hinder the performance such as the dispersed particle size, viscosity, and image definition, and it can be devised so as not to cause a decrease in temporal productivity. preferable.
- dispersion apparatus that can be used in this dispersion step, apparatuses by various known methods can be used and are not particularly limited.
- media dispersion such as sand mill, bead mill, pebble mill, ball mill, pearl mill, basket mill, attritor, dyno mill, bore mill, visco mill, motor mill, SC mill, dry mill, paint conditioner, high speed disk impeller, colloid mill, high pressure homogenizer, nanomizer , Medialess dispersers such as Optimizer.
- media dispersion such as sand mill, bead mill, pebble mill, ball mill, pearl mill, basket mill, attritor, dyno mill, bore mill, visco mill, motor mill, SC mill, dry mill, paint conditioner, high speed disk impeller, colloid mill, high pressure homogenizer, nanomizer , Medialess dispersers such as Optimizer.
- unnecessary physical damage may be caused to the pigment surface as described above.
- the temperature of the aqueous pigment dispersion to be subjected to ultrasonic irradiation is not particularly limited, but it is possible to irradiate ultrasonic waves while controlling the aqueous pigment dispersion so that it becomes a freezing point to 70 ° C. preferable. If the temperature is below the freezing point, ultrasonic dispersion becomes impossible, and if it is above 70 ° C., moisture evaporates, resulting in uncertain conditions such as an increase in pigment concentration.
- a publicly known one, ice cooling, air cooling, water cooling, etc. can be used generally.
- a method of flowing a refrigerant in a jacket (jacket) of a container holding the aqueous pigment dispersion a method of immersing a container containing the aqueous pigment dispersion in the refrigerant, a method of blowing a gas wind,
- a method of cooling with evaporative heat using a coolant such as water and wind can be exemplified. For example, a method of using cooling water that has been cooled to a temperature of more than 0 ° C.
- cooling water can be circulated by the circulation device and at the same time the cooling can be performed by the cooling device.
- cooling water exceeding 0 ° C. does not provide a sufficient cooling effect, it is possible to obtain a cooling water having a temperature lower than that, so that the aqueous pigment dispersion becomes lower in the above temperature range. It becomes possible to carry out ultrasonic irradiation while being held at the same position.
- air cooling it is preferable to use cold air that has been cooled in advance, instead of simply blowing air at ambient temperature.
- the end point of ultrasonic irradiation is determined by measuring the particle size of the pigment particles and the composite particles with a particle gauge or a commercially available particle size measuring device, as well as the viscosity, contact angle, and reflection of the coating film prepared by various methods. It may be determined by measuring physical properties such as luminous intensity and color. Alternatively, the determination may be made by direct observation using a microscope or the like.
- the method for preparing the pigment paste in advance is not particularly limited, and a known dispersion method can be used.
- Examples of the method for preparing the pigment paste include the following (i) to (iii).
- the pigment and the pigment dispersant are kneaded using a kneader such as two rolls or a mixer, and the obtained kneaded product is added to an aqueous medium containing water, and the pigment is then mixed using a stirring / dispersing device.
- a method of preparing a paste A method of preparing a paste.
- the kneader is not particularly limited, and examples thereof include a Henschel mixer, a pressure kneader, a Banbury mixer, and a planetary mixer.
- the stirring / dispersing device is not particularly limited, and examples thereof include an ultrasonic homogenizer, a high-pressure homogenizer, a paint shaker, a ball mill, a roll mill, a sand mill, a sand grinder, a dyno mill, a disperse mat, an SC mill, and a nanomizer.
- an ultrasonic homogenizer a high-pressure homogenizer
- a paint shaker a paint shaker
- a ball mill a roll mill
- a sand mill a sand grinder
- a dyno mill a disperse mat
- SC mill and a nanomizer.
- One of these may be used alone, or two or more devices may be used in combination.
- the amount of pigment in the pigment paste is preferably 5 to 60% by mass, more preferably 10 to 50% by mass.
- the amount of the pigment is less than 5% by mass, the aqueous pigment dispersion prepared from the pigment paste and the aqueous ink are not sufficiently colored, and a sufficient image density tends not to be obtained.
- the amount is more than 60% by mass, the dispersion stability of the pigment tends to decrease in the pigment paste.
- the remaining coarse particles cause various image characteristics to deteriorate, it is preferable to appropriately remove the coarse particles by centrifugation or filtration before and after ink preparation.
- an impurity removal step by ion exchange treatment or ultrafiltration treatment may be performed, followed by post-treatment.
- Ion exchange treatment can remove ionic substances such as cations and anions (divalent metal ions, etc.), and by ultra-treatment, impurities dissolved substances (residual substances during pigment synthesis, excess components in dispersion composition) , Resin not adsorbed to the organic pigment, mixed foreign matter, etc.) can be removed.
- a known ion exchange resin is used in the ion exchange treatment.
- the ultratreatment uses a known ultrafiltration membrane and may be either a normal type or a double capacity up type.
- the aqueous pigment dispersion is diluted with a water-soluble solvent at an arbitrary timing, or a wetting agent (drying inhibitor), a penetrating agent, or other additives, so-called commonly used additives are added. You can also By the addition, it can be used in various applications such as the paint field for automobiles and building materials, the printing ink field such as offset ink, gravure ink, flexo ink and silk screen ink, and the ink jet recording ink field. After ink preparation, coarse particles can be removed by adding a centrifugal separation or filtration treatment step.
- the water-based ink for inkjet recording will be described in detail.
- the wetting agent is added for the purpose of preventing the ink from drying.
- the content of the wetting agent in the ink for the purpose of preventing drying is preferably 3 to 50% by mass.
- the wetting agent used in the present invention is not particularly limited, but a wetting agent that is miscible with water and can prevent clogging of the head of an inkjet printer is preferable.
- glycerin ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol having a molecular weight of 2000 or less
- propylene glycol dipropylene glycol, tripropylene glycol, 1,3-propylene glycol, isopropylene glycol, isobutylene glycol, 1,4-butane
- examples include diol, 1,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, mesoerythritol, pentaerythritol, and the like.
- the inclusion of propylene glycol and 1,3-butyl glycol has safety and excellent effects in ink drying properties and ejection performance.
- the penetrant is added for the purpose of improving the permeability to a recording medium and adjusting the dot diameter on the recording medium.
- the penetrant include lower alcohols such as ethanol and isopropyl alcohol, ethylene oxide adducts of alkyl alcohols such as ethylene glycol hexyl ether and diethylene glycol butyl ether, and propylene oxide adducts of alkyl alcohols such as propylene glycol propyl ether.
- the content of the penetrant in the ink is preferably 0.01 to 10% by mass.
- the surfactant is added to adjust ink properties such as surface tension.
- the surfactant that can be added for this purpose is not particularly limited, and examples include various anionic surfactants, nonionic surfactants, cationic surfactants, and amphoteric surfactants. Of these, anionic surfactants and nonionic surfactants are preferred.
- anionic surfactant examples include alkylbenzene sulfonate, alkylphenyl sulfonate, alkylnaphthalene sulfonate, higher fatty acid salt, sulfate of higher fatty acid ester, sulfonate of higher fatty acid ester, higher alcohol ether. Sulfate salts and sulfonates of the above, higher alkyl sulfosuccinates, polyoxyethylene alkyl ether carboxylates, polyoxyethylene alkyl ether sulfates, alkyl phosphates, polyoxyethylene alkyl ether phosphates, etc.
- dodecylbenzene sulfonate isopropyl naphthalene sulfonate, monobutylphenylphenol monosulfonate, monobutylbiphenyl sulfonate, dibutylphenylphenol disulfate.
- phosphate salt can be mentioned.
- Nonionic surfactants include, for example, polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene sorbitol fatty acid ester, glycerin fatty acid ester , Polyoxyethylene glycerin fatty acid ester, polyglycerin fatty acid ester, sucrose fatty acid ester, polyoxyethylene alkylamine, polyoxyethylene fatty acid amide, fatty acid alkylolamide, alkyl alkanolamide, acetylene glycol, oxyethylene adduct of acetylene glycol, Polyethylene glycol polypropylene glycol block copolymer, etc.
- polyoxyethylene nonyl phenyl ether polyoxyethylene octyl phenyl ether, polyoxyethylene dodecyl phenyl ether, polyoxyethylene alkyl ether, polyoxyethylene fatty acid ester, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester, Fatty acid alkylolamide, acetylene glycol, oxyethylene adduct of acetylene glycol, and polyethylene glycol polypropylene glycol block copolymer are preferred.
- surfactants include silicone surfactants such as polysiloxane oxyethylene adducts; fluorine surfactants such as perfluoroalkyl carboxylates, perfluoroalkyl sulfonates, and oxyethylene perfluoroalkyl ethers.
- Biosurfactants such as spicrispolic acid, rhamnolipid, lysolecithin and the like can also be used.
- surfactants can be used alone or in combination of two or more.
- the addition amount is preferably in the range of 0.001 to 2% by mass, more preferably 0.001 to 1.5% by mass, based on the total mass of the ink. More preferably, the content is in the range of 01 to 1% by mass.
- the addition amount of the surfactant is less than 0.001% by mass, the effect of adding the surfactant tends to be not obtained, and when it exceeds 2% by mass, problems such as blurring of the image are likely to occur. .
- the aqueous pigment dispersion of the present invention exhibits a high optical density and scratch resistance, particularly with respect to plain paper. Of course, it may be used for other absorbent recording members.
- the water-absorbing recording medium include plain paper, (fine) coated paper, fabric, inkjet exclusive paper, inkjet glossy paper, cardboard, wood, and the like.
- colloidal silica In Table 1 below, the colloidal silica used (“Quortron PL series” (trade name) manufactured by Fuso Chemical Industry Co., Ltd.) is described.
- Bionanofiber As the bionanofiber, those shown in Table 2 were used.
- the mode diameter and 80% particle diameter / 20% particle diameter were determined by using a dynamic light scattering nanotrack particle size analyzer UPA-150EX (manufactured by Nikkiso Co., Ltd.) and 0.1% by mass of bio-nanofiber (solvent: water, temperature). (25 ° C.) from the measured value (volume basis).
- the specific surface area was calculated from the particle size distribution measured by the light scattering method using a laser diffraction / scattering particle size distribution measuring apparatus LA-960 (manufactured by Horiba, Ltd.). The measurement conditions are shown below. Measurement range: 0.01 ⁇ m to 3000 ⁇ m, measurement method: wet method, particle diameter standard: volume, dispersion medium: pure water sample refractive index: 1.56-0.00i, dispersion medium refractive index: 1.333-0.00i Dispersion treatment: Built-in ultrasonic wave (30W) 1 minute, Circulation speed: 3, Stirring speed: No Transmission (semiconductor laser light) and transmittance (LED light): 80% or more
- ⁇ c is the crystallinity (%) of cellulose type I
- ⁇ Anionic group-containing organic polymer compound The following were used as the anionic group-containing organic polymer compound.
- (Polysaccharide derivatives having an anionic group) A commercial product was used.
- CMC 1390 manufactured by Daicel Finechem Co., Ltd.
- DN-800H Sodium carboxymethyl cellulose (degree of etherification: 1.0 to 1.5)
- DN-800H Sodium carboxymethyl cellulose (degree of etherification: 1.0 to 1.5)
- DN-800H (Daicel Finechem Co., Ltd.): Carboxymethylcellulose ammonium DN-100L (Daicel Finechem Co., Ltd.): Carboxymethylcellulose ammonium DN-10L (Daicel Finechem Co., Ltd.): Carboxymethylcellulose ammonium
- MEK methyl ethyl ketone
- resin A 50 parts of methyl ethyl ketone
- resin A 50 parts of ion-exchanged water
- KOH potassium hydroxide
- polyether polyol (“PTMG2000”, polytetramethylene glycol manufactured by Mitsubishi Chemical Corporation, number average molecular weight 1000) 140.1 Part by mass and 0.01 part by mass of dibutyltin dilaurate (hereinafter DBTDL) were added, and the reaction was continued at 80 ° C. After confirming that the weight average molecular weight of the reaction product reached the range of 20000 to 50000, the reaction was terminated by adding 1.3 parts by mass of methanol. Next, an organic solvent solution of urethane resin was obtained by adding 41.6 parts by mass of methyl ethyl ketone.
- the mixture was obtained by stirring, and the mixture was distilled under reduced pressure of about 1 to 50 kPa. After confirming that 144 parts by mass of methyl ethyl ketone contained in the mixture had been removed, 0.03 part by mass of Surfynol 440 (manufactured by Air Products) was added under reduced pressure, and vacuum distillation was continued. Next, it was confirmed that 147 parts by mass of water contained in the mixture had been dehydrated, and the vacuum distillation was completed. Next, the non-volatile content was adjusted by adding water to give a resin solid content of 20% by mass as a polyurethane resin solution (UR-1) having an anionic group.
- UR-1 polyurethane resin solution
- ⁇ Preparation Example 1 Ultrasonic Dispersion Method (US) Aqueous Black Ink (Type 1)> 25 parts of pure water was added to 75 parts of the aqueous pigment dispersion obtained in Production Example 1 (equivalent to a pigment concentration of 8%), stirred with a magnetic stirrer, and then filtered through a 1.2 ⁇ m membrane filter. The ultrasonic dispersion method (US) aqueous black ink (Type 1) of Example 1 was obtained. The physical properties of the prepared ink are described in the table below.
- Ultrasonic dispersion method (US) water-based black ink (Type 2)> 50 parts of the aqueous pigment dispersion obtained in Production Example 1 (equivalent to a pigment concentration of 8%) and 50 parts of a separately prepared vehicle (mixing ratio based on mass: 2-pyrrolidone / triethylene glycol monobutyl ether / glycerin / Surfinol 440 / pure) Water 16/16/6/1/61), stirred with a magnetic stirrer, filtered through a 1.2 ⁇ m membrane filter, and ultrasonic dispersion (US) aqueous black ink (Example 14) Type 2) was obtained.
- the physical properties of the prepared ink are described in the table below.
- the type of pigment to be used, the type and addition amount of the anionic group-containing organic polymer compound, the type and addition amount of the bionanofiber were changed to the formulation described in the examples, and ultrasonic waves were applied according to the above-mentioned Preparation Example 1 etc.
- Dispersion method (US) Water-based cyan ink (Type 1) and the like were prepared. The physical properties of the prepared ink are described in the table below.
- ⁇ Production Example 5 Production method of kneading method (PLM) aqueous black pigment dispersion) To a planetary mixer (ACM04LVTJ-B manufactured by Aikosha Seisakusho Co., Ltd.), 50 parts of a mixture (carbon black “# 960” (manufactured by Mitsubishi Chemical Corporation)), 10 parts of an anionic group-containing organic polymer compound (resin A), 34 % Potassium hydroxide aqueous solution (4.4 parts, triethylene glycol 50 parts), and kneaded for 60 minutes at a jacket temperature of 60 ° C. and a stirring blade rotation speed of 25 rpm (revolution speed of 80 rpm).
- PLM kneading method
- ⁇ Preparation Example 3 Kneading method (PLM) water-based black ink (Type 1)> After adding 12.5 parts of pure water to 37.5 parts of the aqueous pigment dispersion (pigment concentration equivalent to 8%) obtained by the method of Production Example 5, the mixture was stirred with a magnetic stirrer and then a 1.2 ⁇ m membrane filter. To obtain a kneading method (PLM) aqueous black ink (Type 1) of Example 11. The physical properties of the prepared ink are listed in the table below.
- the physical properties of the prepared ink are listed in the table below.
- Measurement (ink temperature: 25 ° C.) was performed using a dynamic light scattering nanotrack particle size analyzer UPA-150EX (manufactured by Nikkiso Co., Ltd.). The volume-based (Mv) median diameter (D 50 ) was used as the average particle diameter value.
- the prepared ink was applied to glossy paper with a wire bar # 3. After natural drying for 24 hours, the coated surface was subjected to 45R friction using a Gakushin friction tester (manufactured by Daiei Kagaku Seiki Seisakusho Co., Ltd.) with a weight of 200 g and the number of frictions of 10 times wrapped with PPC paper for friction. I rubbed with a child. Thereafter, the state of the coated surface was visually evaluated by three panelists and evaluated according to the following criteria. G: All three evaluators are “no scratches”. N: One or more evaluators are “scratched”.
Abstract
Description
水性インクは、オフセット印刷方式、グラビア印刷方式、あるいはインクジェット記録方式等各々な印刷方式に適用されるが、中でもインクジェット記録方式はオンデマンド印刷が可能なことから、オフィス等で使用される電子写真(トナー)方式の代替を目的とし現在数多くの検討がなされている。
本発明で使用する顔料は、公知慣用の有機顔料あるいは無機顔料の中から選ばれる少なくとも一種の顔料である。また、本発明は未処理顔料、処理顔料のいずれでも適用することができる。前記処理顔料には、いわゆる自己分散型顔料も含まれる。自己分散型顔料は、例えば、顔料に物理的処理または化学的処理を施すことで、前記親水基を顔料の表面に結合(グラフト)させることにより製造されるからである。
これらの自己分散型顔料は1種単独で使用してもよく、また複数種を組み合わせて使用してもよい。
本発明で使用するコロイダルシリカは、コロイドシリカ、コロイド珪酸とも称される。水中では、水和によって表面にSi-OH基を有する酸化ケイ素のコロイド懸濁液をいい、珪酸ナトリウムの水溶液に塩酸を加えると生成する。最近は、ゾルゲル法などを含め、次々と新しい調製法が開発され、非水溶液中に分散したものや、気相法で作った微粉末状のものがあり、粒子径も数nmから数μmのものまで多彩である。平均粒径としては1~200nm程度のものが好ましい。粒子の組成は不定で、シロキサン結合(-Si-O-、-Si-O-Si-)を形成して、高分子化しているものもある。粒子表面は多孔性で、水中では一般的に負に帯電している。尚、上記平均粒径はレーザー回折散乱法により、あるいは一次粒径が判別できるまで分散された粒子の電子顕微鏡写真より一定面積内に存在する100個の粒子各々の平均粒径として測定することができる。
本発明においては、コロイダルシリカの添加により所望のレオロジー特性を得ることが可能となる。
本発明で使用するバイオナノファイバーは、ナノレベルで均一に微細化(ナノファイバー化)されたセルロースやキチン・キトサンを意味する。このため、特開2013-216766号公報等にあるようにバイオマスナノファイバーと称されることもある。
本発明で使用するバイオナノファイバーは、セルロース、キチン、キトサン以外の不純物があっても特に支障ないが、セルロースナノファイバーあるいはキトサンナノファイバーであることが好ましい。
なお、本願明細書において「ナノファイバー」とは、「直径が1nmから100nmであり、アスペクト比(=長さ/直径)が100以上の繊維状物質」を意味する。よって、本発明においてセルロースナノファイバーとは、セルロース繊維の直径が1nmから100nmであり、アスペクト比(=長さ/直径)が100以上のセルロースを指す。
本発明で使用するセルロースナノファイバーは、平均直径(繊維径ともいう)が1nm~100nmであることが好ましく、1nm~50nmであることがより好ましく、3nm~30nmであることがさらに好ましく、20nm程度であることがさらにより好ましい。アスペクト比は100以上であることが好ましく、100~10000であることがより好ましく、100~2000であることが更により好ましい。かかる範囲であれば、安価で十分な効果が得ることができるからである。これらのセルロースナノファイバーは、単独で用いることもでき、又2種類以上を混合して用いることもできる。
セルロースを構成するグルコース単位は、イス型の立体配座をとるため、グルコピラノース環に対して、水平方向に水酸基が配座され、垂直方法にはCとHのみが配置されるため、セルロースの垂直方向は疎水性、水平方向は親水性となる。ナノファイバー化によって表面積が増大し、この傾向が更に強化される。このため、水性インク中では、セルロースナノファイバーが形成する顔料粒子や後述するアニオン性基含有有機高分子化合物との複合体は、顔料粒子/アニオン性基含有有機高分子化合物間の界面張力を下げ、顔料粒子表面の電荷をコントロールしつつ、顔料粒子間のファンデル・ワールス力に打ち勝ち得る斥力を付与するといった、顔料の安定分散に必須となる高度なバランスを獲得したと考えている。
よって、様々な紙の成分が混じっている普通紙に対する印刷時においても、顔料粒子が被印刷物たる紙に不必要に浸透せず固定化できるため、高い光学濃度を発現し、多色系のカラー印刷においては隣り合った色インクが混色することはないし、耐擦過性に優れる。
ここで、カルボキシル基量は、以下の方法で測定できる。セルロースナノファイバーの0.5質量%スラリー(水分散液)60cm3を調製し、0.1mol/L塩酸水溶液を加えてpH2.5とした後、0.05mol/Lの水酸化ナトリウム水溶液を滴下してpHが11になるまで電気伝導度を測定し、電気伝導度の変化が緩やかな弱酸の中和段階において消費された水酸化ナトリウム量(a)から、下式を用いて算出できる。
本発明で使用するセルロースナノファイバーは、セルロースナノファイバーの酸化処理等の化学処理を施すことが要しないため、ラジカルやアルカリに対する耐性を長時間に亘り向上させる必要がなく、セルロースI型の結晶化度の高いセルロース(結晶化度65~85%程度)を選択する必要はない。すなわち、木材パルプから得られる50~70%(例えば、55~65%)程度の結晶化度を有するセルロースを出発物質とするセルロースナノファイバーで、本発明の効果を発揮することができる。
本発明で使用するキトサンナノファイバーは、平均直径(繊維径ともいう)は1nm~100nmであることが好ましく、1nm~50nmであることがより好ましく、3nm~30nmであることがさらに好ましく、20nm程度であることがさらにより好ましい。アスペクト比は100以上であることが好ましく、100~10000であることがより好ましく、100~2000であることが更により好ましい。かかる範囲であれば、安価で十分な効果が得ることができるからである。これらのキトサンナノファイバーは、単独で用いることもでき、又2種類以上を混合して用いることもできるし、前述のセルロースナノファイバーとも併用できる。
キトサンナノファイバーはセルロースナノファイバーよりも親水性やカチオン性が大きい傾向があるため、高極性なマゼンタ顔料やイエロー顔料の分散系においては、より望ましい物性を発揮する傾向がある。
本発明で使用する前記顔料と前記コロイダルシリカと前記バイオナノファイバーとの比率は、特定の範囲となるように添加することが好ましい。
例えば顔料とコロイダルシリカの比率は、コロイダルシリカ/顔料=1/100~20/100 となるように各々添加することが好ましく、例えばコロイダルシリカとバイオナノファイバーとの比率は、コロイダルシリカ/バイオナノファイバー=1/2~10/1 となるように各々添加することが好ましく、例えばバイオナノファイバーと顔料との比率はバイオナノファイバー/顔料=1/100~15/100 となるように各々添加することが好ましい。
中でも、コロイダルシリカ/顔料=1/100~20/100 あるいは、コロイダルシリカ/バイオナノファイバー=1/2~10/1 であり、且つバイオナノファイバー/顔料=1/100~15/100 であることが好ましい。
中でも、コロイダルシリカ/顔料=2/100~18/100 あるいは、コロイダルシリカ/バイオナノファイバー=3/5~9/1であり、且つバイオナノファイバー/顔料=1/100~14/100であることが好ましい。
中でも、コロイダルシリカ/顔料=3/100~15/100 あるいは、コロイダルシリカ/バイオナノファイバー=3/5~9/1 であり、且つバイオナノファイバー/顔料=1/100~13/100であることが好ましい。
本発明の水性顔料分散体において、溶媒としては水溶性溶媒及び/または水等の水性媒体を使用する。これらは水単独で使用してもよいし、水と水溶性溶媒からなる混合溶媒でもよい。水溶性溶媒としては、例えば、アセトン、メチルエチルケトン、メチルブチルケトン、メチルイソブチルケトン、等のケトン類;メタノール、エタノール、2-プロパノール、2-メチル-1-プロパノール、1-ブタノール、2-メトキシエタノール、等のアルコール類;テトラヒドロフラン、1,4-ジオキサン、1,2-ジメトキシエタン、等のエーテル類;ジメチルホルムアミド、N-メチルピロリドン、等のアミド類が挙げられ、とりわけ炭素数が3~6のケトン及び炭素数が1~5のアルコールからなる群から選ばれる化合物を用いるのが好ましい。
また、その他、水性に溶解しうる水溶性有機溶剤も使用することができる。例えばエチレングリコール、ジエチレングリコール、トリエチレングリコール、テトラエチレングリコール、プロピレングリコール、ポリエチレングリコール、ポリプロピレングリコールなどのグリコール類;ブタンジオール、ペンタンジオール、ヘキサンジオール、およびこれらと同族のジオールなどのジオール類;ラウリン酸プロピレングリコールなどのグリコールエステル;ジエチレングリコールモノエチル、ジエチレングリコールモノブチル、ジエチレングリコールモノヘキシルの各エーテル、プロピレングリコールエーテル、ジプロピレングリコールエーテル、およびトリエチレングリコールエーテルを含むセロソルブなどのグリコールエーテル類;メタノール、エタノール、イソプロピルアルコール、1-プロパノール、2-プロパノール、1-ブタノール、2-ブタノール、ブチルアルコール、ペンチルアルコール、およびこれらと同族のアルコールなどのアルコール類;あるいは、スルホラン;γ-ブチロラクトンなどのラクトン類;N-(2-ヒドロキシエチル)ピロリドンなどのラクタム類;グリセリンおよびその誘導体、ポリオキシエチレンベンジルアルコールエーテルなど、水溶性有機溶剤として知られる他の各種の溶剤などを挙げることができる。これらの水溶性有機溶剤は1種または2種以上混合して用いることができる。
中でも、高沸点、低揮発性で、高表面張力のグリコール類やジオール類等多価アルコール類が好ましく、特にジエチレングリコール、トリエチレングリコール等のグリコール類が好ましい。
本発明で使用するアニオン性基含有有機高分子化合物は、例えば、カルボキシル基、スルホン酸基または燐酸基を含有する、有機高分子化合物が挙げられる。この様なアニオン性基含有有機高分子化合物としては、例えばアニオン性基を有するポリビニル系樹脂、アニオン性基を有するポリエステル系樹脂、アニオン性基を有するアミノ系樹脂、アニオン性基を有するアクリル系樹脂、アニオン性基を有するエポキシ系樹脂、アニオン性基を有するポリウレタン系樹脂、アニオン性基を有するポリエーテル系樹脂、アニオン性基を有するポリアミド系樹脂、アニオン性基を有する不飽和ポリエステル系樹脂、アニオン性基を有するフェノール系樹脂、アニオン性基を有するシリコーン系樹脂、アニオン性基を有するフッ素系高分子化合物、アニオン性基を有する多糖類誘導体等が挙げられる。
中でもアニオン性基を有するアクリル系樹脂やアニオン性基を有するポリウレタン系樹脂は、原料が豊富であり設計が容易であること、顔料分散機能に優れることから好ましい。
アニオン性基を有するアクリル系樹脂は、具体的には、(メタ)アクリル酸等のアニオン性基を有する単量体とそれと共重合可能なその他のエチレン性不飽和単量体との共重合体からなる樹脂が挙げられる。尚、本発明において(メタ)アクリル酸とは、アクリル酸とメタクリル酸との総称を意味するものとする。(メタ)アクリル酸の各種エステルの場合も前記と同様に解釈される。
前記スチレン-アクリル酸系共重合体においてスチレン系モノマーとアクリル酸モノマーとメタクリル酸モノマーの共重合時の総和は、全モノマー成分に対して95質量%以上であることが好ましい。
酸価が低すぎる場合には顔料分散や保存安定性が低下し、また後記するインクジェット記録用水性顔料分散体を調製した場合に、印字安定性が悪くなるので好ましくない。酸価が高すぎる場合には、着色記録画像の耐水性が低下するのでやはり好ましくない。共重合体を該酸価の範囲内とするには、(メタ)アクリル酸を、前記酸価の範囲内となる様に含めて共重合すれば良い。
本発明で使用するアニオン性基を有するポリウレタン系樹脂は、具体的には、カルボキシ基やスルホン酸基等のアニオン性基を有するポリオールとポリイソシアネート、さらに必要に応じて汎用のアニオン性基を有さないポリオールや鎖伸長剤を反応させて得たウレタン樹脂があげられる。
また、スルホン酸基を有するポリオールとしては、例えば5-スルホイソフタル酸、スルホテレフタル酸、4-スルホフタル酸、5[4-スルホフェノキシ]イソフタル酸等のジカルボン酸、及びそれらの塩と、前記低分子量ポリオールとを反応させて得られるポリエステルポリオールが挙げられる。
中でも、印字画像の耐光変色が起こり難い点では、脂肪族ジイソシアネート化合物または脂環族ジイソシアネートが好ましい。
また前記ポリオールのほか、印字物における皮膜硬度の調整等を目的として、低分子量のジオールを適宜併用しても良い。例としては、エチレングリコール、ジエチレングリコール、プロピレングリコール、ジプロピレングリコール、1,2-プロパンジオール、1,3-プロパンジオール、1,4-ブタンジオール等が挙げられる。
酸価が低すぎる場合には顔料分散や保存安定性が低下するおそれがあり、酸価が高すぎる場合には形成画像の耐水性が低下するおそれがある。共重合体を該酸価の範囲内とするには、カルボキシ基を有するポリオールを、前記酸価の範囲内となる様に含めて共重合すれば良い。
本発明においてアニオン性基を有するアクリル系樹脂及びアニオン性基を有するポリウレタン系樹脂は、塩基性化合物により中和して使用することが好ましい。塩基性化合物としては公知のものを使用でき、例えばカリウム、ナトリウムなどのアルカリ金属の水酸化物;カリウム、ナトリウムなどのアルカリ金属の炭酸塩;カルシウム、バリウムなどのアルカリ土類金属などの炭酸塩;水酸化アンモニウム等の無機系塩基性化合物や、トリエタノールアミン、N,N-ジメタノールアミン、N-アミノエチルエタノールアミン、ジメチルエタノールアミン、N-N-ブチルジエタノールアミンなどのアミノアルコール類、モルホリン、N-メチルモルホリン、N-エチルモルホリンなどのモルホリン類、N-(2-ヒドロキシエチル)ピペラジン、ピペラジンヘキサハイドレートなどのピペラジン等の有機系塩基性化合物が挙げられる。中でも、水酸化カリウム、水酸化ナトリウム、水酸化リチウムに代表されるアルカリ金属水酸化物は、水性顔料分散体の低粘度化に寄与し、水性インクジェット記録用インクとした場合に吐出安定性の面から好ましく、特に水酸化カリウムが好ましい。
本発明における水性顔料分散体に、アニオン性基を有する多糖類誘導体を配合することもまた好ましい。アニオン性基を有する多糖類誘導体は、ポリアニオン性多糖類であれば特に限定されない。具体的には、ヒアルロン酸、アルギン酸、ペクチン、ポリガラクチュロン酸などの天然多糖類、カルボキシメチルプルラン、カルボキシメチルキチン、カルボキシメチルキトサン、カルボキシメチルマンナン、カルボキシメチルスターチ、カルボキシメチルデキストラン、カルボキシエチルセルロース、カルボキシメチルプルランなどのカルボキシアルキル多糖類、酸化セルロースや酸化でんぷんなどの酸化多糖類、コンドロイチン硫酸、デルマタン硫酸、ヘパリンやヘパラン硫酸など硫酸基を含む多糖類を挙げることができる。そのなかでもカルボキシメチルセルロースやヒアルロン酸が好ましく、特にカルボキシメチルセルロースが好ましい。原料多糖類の重量平均分子量は特に限定されないが、重合度が高くなるに従い、粘度も高くなる傾向があることから、目的に応じて選択すれば良い。あえて例示するならば、5万以上100万以下が好ましく、5万以上50万以下がより好ましい。
本発明の水性顔料分散体の製造方法は、特に限定なく公知の方法で得ることができる。すなわち、バイオナノファイバー等は、後述するメディアレス分散の前後を問わず、任意のタイミングで配合することが可能である。例えば、(1)本発明の少なくとも顔料とバイオナノファイバー等を含んでなる水性顔料分散体を、必要に応じてその他の添加剤を添加して、メディアレス分散により調製する方法、
(2)予め顔料の高濃度水性分散液(顔料ペースト)を作成し、それを水性媒体で希釈する際に同時にバイオナノファイバー等、必要に応じてその他の添加剤を添加して調製する方法、等があげられる。
本発明において、(1)メディアレス分散とは、具体的には、超音波分散法、高速ディスクインペラー、コロイドミル、ロールミル、高圧ホモジナイザー、ナノマイザー、アルティマイザー等による分散法等があげられるが、生産性やメディアの摩耗によるコンタミ(異物の混入や汚染)などを顧慮すると超音波分散法が好ましい。本発明においては、以下超音波分散法を用いた例を用いて詳細に述べる。
また、この時の粘度範囲は流動性を確保する観点から、0.1~100mPa・sが好ましく、0.5~50mPa・sがさらには好ましく、0.5~30mPa・sがさらにより好ましく、1.0~20mPa・sが最も好ましい。また、この時の顔料濃度は、1~30質量%が好ましく、1~25質量%がさらには好ましく、3~20質量%がさらにより好ましく、5~20質量%が最も好ましい。
この分散工程において用いることのできる分散装置として、既に公知の種々の方式による装置が使用でき、特に限定されるものではない。例えばサンドミル、ビーズミル、ペブルミル、ボールミル、パールミル、バスケットミル、アトライター、ダイノーミル、ボアミル、ビスコミル、モーターミル、SCミル、ドライスミル、ペイントコンディショナー等のメディア分散や、高速ディスクインペラー、コロイドミル、高圧ホモジナイザー、ナノマイザー、アルティマイザー等のメディアレス分散機が上げられる。ただし前記したように顔料表面に不必要な物理的損傷を与える場合もあることに留意すべきである。
例えば、冷媒として、予め0℃を越えて20℃以下、好ましくは0℃を越えて10℃以下に冷却された冷却水を使用する方法は、比較的に経済的であり、しかも冷却効率も優れているため望ましい方法の一つである。この際、冷却水を循環装置で循環すると同時に、冷却装置で冷却も行うことが出来る。この際、冷却水中に、エチレングリコール、ジエチレングリコールなどの凍結温度を下げるものを加えたり、塩化ナトリウムなどを加えて凝固点降下を起こさせるのも大変望ましい。その結果、0℃を越える冷却水では十分な冷却効果が得られない時でも、それ以下の温度の冷却水とすることが出来、より水性顔料分散体を前記温度範囲内でもより低温となる様に保持して超音波照射することが可能になる。風冷する場合も、単に雰囲気温度の風を吹き付けるのではなく、予め冷やした冷風を用いることが好ましい。
予め顔料ペーストを作成する方法は、特に限定はなく、公知の分散方法を使用することができる。
(i)顔料分散剤及び水を含有する水性媒体に、顔料を添加した後、攪拌・分散装置を用いて顔料を該水性媒体中に分散させることにより、顔料ペーストを調製する方法。
(ii)顔料、及び顔料分散剤を2本ロール、ミキサー等の混練機を用いて混練し、得られた混練物を、水を含む水性媒体中に添加し、攪拌・分散装置を用いて顔料ペーストを調製する方法。
(iii)メチルエチルケトン、テトラヒドロフラン等のような水との相溶性を有する有機溶剤中に顔料分散剤を溶解して得られた溶液に顔料を添加した後、攪拌・分散装置を用いて顔料を有機溶液中に分散させ、次いで水性媒体を用いて転相乳化させた後、前記有機溶剤を留去し顔料ペーストを調製する方法。
また、攪拌・分散装置としても特に限定されることなく、例えば、超音波ホモジナイザー、高圧ホモジナイザー、ペイントシェーカー、ボールミル、ロールミル、サンドミル、サンドグラインダー、ダイノーミル、ディスパーマット、SCミル、ナノマイザー等を挙げられる。これらのうちの1つを単独で用いてもよく、2種類以上装置を組み合わせて用いてもよい。
前記水性顔料分散体は、必要に応じて、任意のタイミングで、水溶性溶媒で希釈する、あるいは湿潤剤(乾燥抑止剤)、浸透剤、あるいはその他の添加剤、いわゆる公知慣用の添加剤を添加することもできる。当該添加により、自動車や建材用の塗料分野や、オフセットインキ、グラビアインキ、フレキソインキ、シルクスクリーンインキ等の印刷インキ分野、あるいはインキジェット記録用インク分野等様々な用途に使用することができる。インクの調製後に、遠心分離あるいは濾過処理工程を追加して、粗大粒子除去を行うこともできる。ここでは、インクジェット記録用水性インクについて、詳述する。
前記湿潤剤は、インクの乾燥防止を目的として添加する。乾燥防止を目的とする湿潤剤のインク中の含有量は3~50質量%であることが好ましい。
本発明で使用する湿潤剤としては特に限定はないが、水との混和性がありインクジェットプリンターのヘッドの目詰まり防止効果が得られるものが好ましい。例えば、グリセリン、エチレングリコール、ジエチレングリコール、トリエチレングリコール、分子量2000以下のポリエチレングリコール、プロピレングリコール、ジプロピレングリコール、トリプロピレングリコール、1,3-プロピレングリコール、イソプロピレングリコール、イソブチレングリコール、1,4-ブタンジオール、1,3-ブタンジオール、1,5-ペンタンジオール、1,6-ヘキサンジオール、メソエリスリトール、ペンタエリスリトール、等が挙げられる。中でも、プロピレングリコール、1,3-ブチルグリコールを含むことが安全性を有し、かつインク乾燥性、吐出性能に優れた効果が見られる。
前記浸透剤は、被記録媒体への浸透性改良や記録媒体上でのドット径調整を目的として添加する。
浸透剤としては、例えばエタノール、イソプロピルアルコール等の低級アルコール、エチレングリコールヘキシルエーテルやジエチレングリコールブチルエーテル等のアルキルアルコールのエチレンオキシド付加物やプロピレングリコールプロピルエーテル等のアルキルアルコールのプロピレンオキシド付加物等が挙げられる。
インク中の浸透剤の含有量は0.01~10質量%であることが好ましい。
前記界面活性剤は、表面張力等のインク特性を調整するために添加する。このために添加することのできる界面活性剤は特に限定されるものではなく、各種のアニオン性界面活性剤、ノニオン性界面活性剤、カチオン性界面活性剤、両性界面活性剤などが挙げられ、これらの中では、アニオン性界面活性剤、ノニオン性界面活性剤が好ましい。
本発明の水性顔料分散体は、特に普通紙に対しても高い光学濃度及び耐擦過性を発現する。その他の吸収性の記録部材に使用してももちろん構わない。吸水性の記録媒体の例には、普通紙、(微)塗工紙、布帛、インクジェット専用紙、インクジェット光沢紙、ダンボール、木材、などが含まれる。
なお、特に断りがない限り、「部」は「質量部」、「%」は「質量%」である。
下記の表1に、使用したコロイダルシリカ(扶桑化学工業(株)製「クォートロンPLシリーズ」(商品名))に関して記載した。
バイオナノファイバーは、表2に記載のものを使用した。
測定レンジ:0.01μm~3000μm、測定手法:湿式法、粒子径基準:体積、分散媒:純水
試料屈折率:1.56-0.00i、分散媒屈折率:1.333-0.00i
分散処理:内蔵超音波(30W)1分、循環速度:3、攪拌速度:しない
透過率(半導体レーザ光)および透過率(LED光):80%以上
アニオン性基含有有機高分子化合物としては、以下のものを使用した。
(アニオン性基を有する多糖類誘導体)
市販品を使用した。
CMC1390(ダイセルファインケム株式会社製):カルボキシメチルセルロースナトリウム(エーテル化度1.0~1.5)
DN-800H(ダイセルファインケム株式会社製):カルボキシメチルセルロースアンモニウム
DN-100L(ダイセルファインケム株式会社製):カルボキシメチルセルロースアンモニウム
DN-10L(ダイセルファインケム株式会社製):カルボキシメチルセルロースアンモニウム
<製造例101:アニオン性基を有するアクリル系樹脂の溶液(SA-1)>
モノマー組成比において、スチレン/メタアクリル酸/アクリル酸=77/13/10(質量比)であり、重量平均分子量8800、酸価150mgKOH/g、ガラス転移点107℃である樹脂Aを作製した。メチルエチルケトン(以下、MEKと略記する)50部、前記樹脂A50部、これにイオン交換水87.4部、34質量%の水酸化カリウム(KOH)水溶液22gを加え、良く撹拌し、樹脂溶液を得た。この樹脂溶液について、ウォーターバス温度45℃、40hPaの減圧条件でMEKを除去し、樹脂固形分20%としたものをアニオン性基を有するアクリル系樹脂の溶液(SA-1)とした。
<製造例102:アニオン性基を有するポリウレタン系樹脂の溶液(UR-1)>
温度計、窒素ガス導入管及び攪拌機を備えた窒素置換された容器中にメチルエチルケトン64.2質量部を加え、該メチルエチルケトン中で、2,2-ジメチロールプロピオン酸18.4質量部及びイソホロンジイソシアネート33.9質量部を混合し、80℃で4時間反応させた。4時間後、メチルエチルケトンを更に38.2質量部を供給し、60℃以下に冷却した後、ポリエーテルポリオール(「PTMG2000」三菱化学株式会社製のポリテトラメチレングリコール、数平均分子量1000)140.1質量部及びジブチル錫ジラウリレート(以下DBTDL)0.01質量部を追加し、80℃で反応を継続させた。
反応物の重量平均分子量が20000から50000の範囲に達したことを確認した後、メタノール1.3質量部を投入することによって反応を終了した。次いで、メチルエチルケトン41.6質量部を追加することによってウレタン樹脂の有機溶剤溶液を得た。
次いで、前記混合物を約2時間エージングした後、前記混合物中にサーフィノール440(エアープロダクツ社製、アセチレングリコールのエチレンオキサイド付加物、不揮発分100質量%)0.07質量部を加え、約20分攪拌することにより混合物を得、該混合物を約1~50kPaの減圧条件下で蒸留した。
前記混合物中に含まれるメチルエチルケトンの144質量部を除去したことを確認した後、減圧下でサーフィノール440(エアープロダクツ社製)0.03質量部を追加し、減圧蒸留を継続した。次いで、前記混合物中に含まれる水の147質量部を脱水したことを確認し、前記減圧蒸留を終了した。
次いで、水を加えることによって不揮発分を調整し、樹脂固形分20質量%としたものをアニオン性基を有するポリウレタン系樹脂の溶液(UR-1)とした。
顔料等としては、以下の市販品を使用した。
(顔料)
#960(三菱化学株式会社製):カーボンブラック
FASTOGEN Blue TGR(DIC株式会社製):C.I.Pigment Blue 15:3
FASTOGEN Super Magenta RY(DIC株式会社製):C.I.Pigment Red 122
Fast Yellow 7413(山陽色素株式会社製):C.I.Pigment Yellow 74
金属製ビーカーに、「#960」(三菱化学株式会社製カーボンブラック)20部、アニオン性基含有有機高分子化合物の溶液(SA-1)20部、トリエチレングリコール5部、純水により全量100部となるように加え、手動攪拌した。その後、超音波分散機(Hielscher社製UP200St、運転周波数:26KHz、運転出力:160W)により10分間超音波分散した。この超音波分散処理後の混合物100部に、バイオナノファイバー「BiNFi-s2%セルロース」(スギノマシン株式会社製、製品名(略記号):CEL-NF)1.0部(固形分換算)、コロイダルシリカ「クォートロンPL-3」(扶桑化学工業(株)製、製品名(略記号):PL-3)2.0部(固形分換算)、純水により全量250部となるように加え、手動攪拌後、超音波分散機(Hielscher社製UP200St、運転周波数:26KHz、運転出力:160W)により25分間超音波分散し、水性ブラック顔料分散体(顔料濃度8%相当)を得た。
使用する顔料、アニオン性基含有有機高分子化合物、バイオナノファイバーおよびコロイダルシリカの種類と添加量を、実施例に記載した配合に変更した以外は、上述の製造方法に従って、水性シアン顔料分散体等を調製した。
表3に、超音波分散法(US)水性顔料分散体の仕込み量を例示した。
製造例1で得た水性顔料分散体(顔料濃度8%相当)75部に、純水を25部加えて、マグネチックスターラーで攪拌してから、1.2μmのメンブレンフィルターで濾過して、実施例1の超音波分散法(US)水性ブラックインク(Type1)を得た。調製したインクの物性等は後述の表に記載した。
製造例1で得た水性顔料分散体(顔料濃度8%相当)50部に、別途調製したビヒクル50部(質量基準配合比:2-ピロリドン/トリエチレングリコールモノブチルエーテル/グリセリン/サーフィノール440/純水=16/16/6/1/61)を加え、マグネチックスターラーで攪拌してから、1.2μmのメンブレンフィルターで濾過して、実施例14の超音波分散法(US)水性ブラックインク(Type2)を得た。調製したインクの物性等は後述の表に記載した。
プラネタリーミキサー(株式会社愛工舎製作所製ACM04LVTJ-B)に、混合物(カーボンブラック「#960」(三菱化学株式会社製)50部、アニオン性基含有有機高分子化合物(樹脂A)10部、34%水酸化カリウム水溶液4.4部、トリエチレングリコール50部)を仕込み、ジャケット温度60℃、攪拌羽根回転数25rpm(公転数80rpm)にて60分間混練を行なった。更に、得られた混練物全部を家庭用ミキサー(象印社製ヘルシーミックス)に投入し、純水218.6部を加え密栓し20分間撹拌溶解し、水性混合物MX333部を得た。金属製ビーカーに、この水性混合物MX53.33部と、バイオナノファイバー「BiNFi-s2%セルロース」(スギノマシン株式会社製、製品名(略記号):CEL-NF)0.3部(固形分換算)、コロイダルシリカ「クォートロンPL-10H」(扶桑化学工業(株)製、製品名(略記号):PL-10H)1.0部(固形分換算)および純水により全量100部になるように加え、ホモジナイザー(シルバーソン社製ローターステーター)にて8000RPMで11分間撹拌混合後、更に純水で希釈し、混練法(PLM)水性ブラック顔料分散体(顔料濃度8%相当)を得た。
使用する顔料アニオン性基含有有機高分子化合物バイオナノファイバーおよびコロイダルシリカの種類と添加量を、実施例に記載した配合に変更した以外は、上述の製造方法に従って、混練法(PLM)水性シアン顔料分散体等を調製した。表4に、混練法(PLM)水性顔料分散体の仕込み量を例示した。
製造例5の方法で得た水性顔料分散体(顔料濃度8%相当)37.5部に、純水を12.5部加えて、マグネチックスターラーで攪拌してから、1.2μmのメンブレンフィルターで濾過して、実施例11の混練法(PLM)水性ブラックインク(Type1)を得た。調製したインクの物性等を後述の表に記載した。
製造例5の方法で得た水性顔料分散体(顔料濃度8%相当)25部に、別途調製したビヒクル25部(質量基準配合比:2-ピロリドン/トリエチレングリコールモノブチルエーテル/グリセリン/サーフィノール440/純水=16/16/6/1/61)を加え、マグネチックスターラーで攪拌してから、1.2μmのメンブレンフィルターで濾過して、実施例47の混練法(PLM)水性ブラックインク(Type2)を得た。調製したインクの物性等を後述の表に記載した。
(pH測定方法)
MM-60R(東亜ディーケーケー株式会社製)を用いて測定(インク温度25℃)した。
ViscometerTV-20(東機産業株式会社製)を用いて、測定(インク温度25℃)した。
動的光散乱式ナノトラック粒度分析計UPA-150EX(日機装株式会社製)用いて、測定(インク温度25℃)した。平均粒子径の値として、体積基準(Mv)のメジアン径(D50)を用いた。
(光学濃度(O.D.)値の測定)
調製した前記インクを、ワイヤーバー#3にてPPC用紙に塗布した。24時間自然乾燥後、塗布物の光学濃度(O.D.))を測定した。測定には「Gretag Macbeth Spectro Scan Transmission」(米X-Rite社)を使用し、塗布物の光学濃度(O.D.)値として、縦3点×横3点の合計9点測定の平均値を採用した。
なお、光学濃度向上は、下記式に従い算出し、以下に示す評価基準にしたがって光学濃度(O.D.)を評価した。
G:3%以上の光学濃度の向上あり。
N:3%以上の光学濃度の向上なし。
調製した前記インクを、ワイヤーバー#3にて光沢紙に塗布した。24時間自然乾燥後、塗布した面を、学振型摩擦試験機(株式会社大栄科学精機製作所製)を用いて、加重200g、摩擦回数10回の条件で、摩擦用PPC用紙を巻き付けた45R摩擦子で擦った。その後、塗布面の状態をパネラー3名により目視評価し、以下の基準に従って評価した。
G:評価者3名とも「キズ無し」。
N:評価者1名以上が「キズ有り」。
調製した前記インクを、ワイヤーバー#3にてPPC用紙に塗布した。24時間自然乾燥後、塗布物上のインク塗布面と塗布されていない面の境界を、市販の水性蛍光ペン(FABER-CASTELL社製テキストライナー)でなぞった場合の、汚れ度合いを目視にて観察し、以下の基準に従って評価した(パネラー3名)。
G:蛍光ペンでなぞっても尾引き等の汚れがない、あるいは、尾引きするものの、
実用上問題がないレベルである。
N:蛍光ペンでなぞると著しい尾引きが発生し、ひどい汚れを認める。
吐出性、及び印刷性能について、恒温恒湿室(室温25℃、湿度50%)において、サーマル型インクジェットノズルを有するインクジェット記録装置(ヒューレットパッカード社製ENVY4500)に、水性インクを装填した。その後、被記録材としてPPC用紙上へ、テスト印刷用パターン(文字部、罫線部、ベタ部あり)を用いて10分連続して印刷を行った。10分連続印刷後の紙面をパネラー3名により目視観察し、印刷パターンの欠けや滲みに関し、以下の基準に従って評価した。
G:パネラー3名が、印刷パターンの欠けや滲みを認めない。
M:パネラー1名のみが、印刷パターンの欠けや滲みを認めた(他のパネラー2名は、印刷パターンの欠けや滲みを認めない。)。
N:パネラー2名以上が、印刷パターンの欠けや滲みを認めた。
Claims (5)
- 少なくとも顔料と、コロイダルシリカと、平均直径が1nm~100nmであり且つアスペクト比が100以上であるバイオナノファイバーと、アニオン性基含有有機高分子化合物とを含んでなることを特徴とする水性顔料分散体。
- 前記バイオナノファイバーが、セルロースナノファイバー又はキトサンナノファイバーである請求項1に記載の水性顔料分散体。
- 前記顔料と前記コロイダルシリカと前記バイオナノファイバーとの比率が、
(1)コロイダルシリカ/顔料=1/100~20/100、あるいは、
(2)コロイダルシリカ/バイオナノファイバー=1/2~10/1 であり、且つ
(3)バイオナノファイバー/顔料=1/100~15/100
を満たす請求項1または2に記載の水性顔料分散体。 - 前記アニオン性基含有有機高分子化合物が、アニオン性基を有するアクリル系樹脂、アニオン性基を有するポリウレタン系樹脂、及びアニオン性基を有する多糖類誘導体からなる群から選択される少なくとも1種である請求項1~3のいずれかに記載の水性顔料分散体。
- 請求項1~4のいずれかに記載の水性顔料分散体を用いた水性インク。
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JP6443607B1 (ja) * | 2017-06-22 | 2018-12-26 | Dic株式会社 | 水性顔料分散体 |
WO2021024843A1 (ja) * | 2019-08-06 | 2021-02-11 | 花王株式会社 | 水性グラビアインキセット |
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