Classifications

• • 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
  • C09D17/004—Pigment pastes, e.g. for mixing in paints containing an inorganic pigment
  • C09D17/007—Metal oxide
  • C09D17/008—Titanium dioxide
• • 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
  • C09D11/326—Inkjet printing inks characterised by colouring agents containing carbon black characterised by the pigment dispersant
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F283/00—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G
  • C08F283/06—Macromolecular compounds obtained by polymerising monomers on to polymers provided for in subclass C08G on to polyethers, polyoxymethylenes or polyacetals
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K9/00—Use of pretreated ingredients
  • C08K9/02—Ingredients treated with inorganic substances
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L51/00—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L51/08—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers grafted on to macromolecular compounds obtained otherwise than by reactions only involving unsaturated carbon-to-carbon bonds
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/36—Compounds of titanium
  • C09C1/3607—Titanium dioxide
  • C09C1/3653—Treatment with inorganic compounds
  • C09C1/3661—Coating
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09C—TREATMENT OF INORGANIC MATERIALS, OTHER THAN FIBROUS FILLERS, TO ENHANCE THEIR PIGMENTING OR FILLING PROPERTIES ; PREPARATION OF CARBON BLACK  ; PREPARATION OF INORGANIC MATERIALS WHICH ARE NO SINGLE CHEMICAL COMPOUNDS AND WHICH ARE MAINLY USED AS PIGMENTS OR FILLERS
  • C09C1/00—Treatment of specific inorganic materials other than fibrous fillers; Preparation of carbon black
  • C09C1/36—Compounds of titanium
  • C09C1/3607—Titanium dioxide
  • C09C1/3676—Treatment with macro-molecular organic compounds
• • 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
• • 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
• • 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
• • 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
  • C09D11/54—Inks based on two liquids, one liquid being the ink, the other liquid being a reaction solution, a fixer or a treatment solution for the ink
• • 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
  • C09D151/00—Coating compositions based on graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Coating compositions based on derivatives of such polymers
  • C09D151/08—Coating compositions based on graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Coating compositions based on derivatives of such polymers grafted on to macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
• • 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
• • 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
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/02—Emulsion paints including aerosols
  • C09D5/024—Emulsion paints including aerosols characterised by the additives
  • C09D5/027—Dispersing agents
• • 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
  • C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
  • C09D7/40—Additives
  • C09D7/60—Additives non-macromolecular
  • C09D7/61—Additives non-macromolecular inorganic
  • C09D7/62—Additives non-macromolecular inorganic modified by treatment with other compounds
• • C—CHEMISTRY; METALLURGY
  • C01—INORGANIC CHEMISTRY
  • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
  • C01P2006/00—Physical properties of inorganic compounds
  • C01P2006/60—Optical properties, e.g. expressed in CIELAB-values
  • C01P2006/62—L* (lightness axis)
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
  • C08K3/00—Use of inorganic substances as compounding ingredients
  • C08K3/18—Oxygen-containing compounds, e.g. metal carbonyls
  • C08K3/20—Oxides; Hydroxides
  • C08K3/22—Oxides; Hydroxides of metals
  • C08K2003/2237—Oxides; Hydroxides of metals of titanium
  • C08K2003/2241—Titanium dioxide

Definitions

• the present invention relates to a white pigment dispersion that can be used for producing a white pigment ink, an ink composition using the white pigment dispersion, and an image forming method using the ink composition.
• This aqueous pigment dispersion generally comprises a pigment and a water-soluble anionic or nonionic surfactant having a hydrophilic group and a lipophilic group as a dispersant, or a polymer dispersant having a specific monomer composition. , Then, after mixing in water, it is obtained by finely dispersing the glass beads, zirconia beads, titania beads, stainless steel balls and the like with an attritor or a milling machine (Patent No. 4579966).
• an ink that can be used for coloring, printing, writing, etc. can be obtained.
• the medium is such that the ink easily permeates, such as paper and textile products, it is easy that a clear image cannot be obtained due to lack of concealment of the medium by the ink. Further, when the medium has colors, images, and the like, those colors and images appear through the image formed by using the ink, and it is easy that the desired clear image cannot be obtained.
• Ink for forming the desired image is used as a means for dealing with the problem that the desired clear image cannot be obtained due to the lack of concealment due to the penetration of the ink or the color or image of the medium. Prior to this, white ink is often used to cover the medium.
• titanium dioxide is preferable from the viewpoint of hiding performance, but titanium dioxide has a high specific gravity and is easily settled, and the ink using titanium dioxide is stable over time. Has the problem of lacking.
• the viscosity of ink used for inkjet printing is as low as 1/10000 to 1/1000 of general printing ink, and it is difficult to maintain a stable dispersed state (Patent No. 5647405). ).
• the contained white pigment is less likely to settle and has excellent storage stability. Is required.
• the present invention provides a white pigment dispersion in which the contained white pigment does not easily settle and has excellent storage stability, an ink composition using the white pigment dispersion, and an image forming method using the ink composition.
• the purpose is.
• the present inventors have obtained at least the use of titanium dioxide surface-treated with alumina, a polymer dispersant, and an aqueous liquid as a solvent or a dispersion medium.
• the present invention has been completed by finding that a white pigment dispersion having excellent storage stability in which titanium dioxide does not easily settle can be obtained.
• the present invention can be expressed as follows, for example.
• the predetermined white pigment is at least titanium dioxide surface-treated with alumina.
• the polymer dispersant has a structure in which a water-soluble molecular chain is grafted to a main chain having a pigment adsorbing group, and has an overall weight average molecular weight in the range of 2000 to 50,000, and the weight average molecular weight of the graft chain.
• Is in the range of 150 to 3000 A white pigment dispersion characterized in that the difference between the lightness L value of the coating film due to the white pigment dispersion before the centrifugation treatment and the brightness L value of the coating film due to the supernatant liquid after the centrifugation treatment is less than 25.
• the main chain of the polymer dispersant has at least one selected from the group consisting of a carboxy group or a salt thereof, a sulfonic acid group or a salt thereof, and a phosphoric acid group or a salt thereof as a pigment adsorbing group.
• the white pigment dispersion according to any one of (1) to (5) above.
• a white pigment dispersion in which titanium dioxide contained as a white pigment does not easily settle and has excellent storage stability, and an ink composition using the white pigment dispersion can be obtained, and the ink composition thereof. Can be used to form an image by the inkjet method.
• the white pigment dispersion of the present invention has a white pigment dispersed in an aqueous liquid, and can be used for producing a white pigment ink or other pigment ink.
• the white pigment dispersion of the present invention contains at least a predetermined white pigment, a polymer dispersant, and an aqueous liquid as a solvent or a dispersion medium.
• the predetermined white pigment is at least titanium dioxide surface-treated with alumina, for example, titanium dioxide surface-treated with alumina, titanium dioxide surface-treated with alumina and silica, titanium dioxide surface-treated with alumina and zirconia. Can be mentioned.
• the polymer dispersant has a structure in which a water-soluble molecular chain is grafted to a main chain having a pigment adsorbing group, and the total weight average molecular weight is in the range of 2000 to 50,000, and the weight average molecular weight of the graft chain is 150. It is in the range of ⁇ 3000.
• the white pigment dispersion of the present invention can improve the dispersion stability of the predetermined white pigment by containing such a predetermined white pigment and a polymer dispersant. Therefore, an ink composition using the white pigment dispersion can be obtained in a stable state in which the predetermined white pigment does not easily settle.
• the difference between the brightness L value of the coating film before the centrifugation treatment of the white pigment dispersion of the present invention and the brightness L value of the coating film due to the supernatant after the centrifugation treatment is less than 25.
• the 10% by volume portion of the supernatant side (center side in the centrifugation treatment) of the white pigment dispersion treated by centrifugation is referred to as a supernatant liquid (including predetermined white pigment particles).
• the predetermined white pigment in the white pigment dispersion of the present invention that is, at least titanium dioxide surface-treated with alumina, can be assumed to have a positive zeta potential of the predetermined white pigment in the aqueous liquid.
• the predetermined white pigment in the aqueous liquid exhibits an electrical affinity for the negatively charged pigment adsorbing group having in the main chain of the polymer dispersant due to the positive zeta potential, and is contained in the aqueous liquid. Can be suitably dispersed.
• the content of the predetermined white pigment (amount with respect to the total amount of the white pigment dispersion) in the white pigment dispersion of the present invention is preferably 25 to 75% by weight from the viewpoint of hiding property and dispersion stability. It is more preferably 30 to 70% by weight, still more preferably 40 to 60% by weight.
• titanium dioxide in the predetermined white pigment any of anatase-type, brookite-type, and rutile-type crystal structures can be used, but titanium dioxide having a rutile-type crystal structure having particularly high concealment is preferable.
• the polymer dispersant in the white pigment dispersion of the present invention that is, at least one selected from the group consisting of a pigment adsorbing group (for example, a carboxy group or a salt thereof, a sulfonic acid group or a salt thereof, and a phosphoric acid group or a salt thereof).
• a pigment adsorbing group for example, a carboxy group or a salt thereof, a sulfonic acid group or a salt thereof, and a phosphoric acid group or a salt thereof.
• a structure in which a water-soluble molecular chain for example, a polyalkylene glycol chain such as polyethylene glycol
• the total weight average molecular weight is in the range of 2000 to 50,000, and the weight of the graft chain.
• a polymer dispersant having an average molecular weight in the range of 150 to 3000 a polymer dispersant having an acid value of 20 to 400 mgKOH / g is preferably used.
• the polymer dispersant in the white pigment dispersion of the present invention is composed of a polymer dispersant having a pigment dispersion ability, for example, an aliphatic vinyl monomer having an acid group, an aromatic or aliphatic vinyl monomer copolymerizable therewith, and the like.
• the polymer can be selected from those neutralized with a basic substance.
• Examples of the aliphatic vinyl monomer having an acid group include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, metallicylsulfonic acid, allylsulfonic acid, vinylsulfonic acid, and styrenesulfonic acid.
• Examples thereof include 2-methacryloyloxyethyl acid phosphate (including these anhydrides or salts), and only one type may be used, or two or more types may be used in combination.
• Examples of the aromatic vinyl monomer copolymerizable with the aliphatic vinyl monomer having an acid group include styrene, ⁇ -methylstyrene, vinyltoluene and the like, and only one type is used. Two or more types can be used together.
• Examples of the aliphatic vinyl monomer copolymerizable with the aliphatic vinyl monomer having an acid group include, for example. Ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, diethylhexyl (meth) acrylate, etc.
• (Meta) acrylic acid esters Carboxylic acid vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate; Alkylating vinyl ethers such as propyl vinyl ether and butyl vinyl ether; Unsaturated hydrocarbons such as ethylene, propylene, and isobutylene can be mentioned, and only one type can be used, or two or more types can be used in combination.
• a macromonomer having a polymerizable functional group at the end of the water-soluble molecular chain can be used.
• macromonomers include polyalkylene glycols such as polyethylene glycol, and specific examples thereof include polyethylene glycol mono (meth) acrylate, polyethylene glycol monovinyl ether, polyethylene glycol monoallyl ether, and polyethylene glycol. Examples thereof include, but are not limited to, monopropenyl ether, methoxypolyethylene glycol vinyl ether, and methoxypolyethylene glycol allyl ether.
• the molecular weight of the polymer dispersant can be adjusted using, for example, a chain transfer agent such as dodecyl mercaptan, mercaptopropionic acid, or ⁇ -methylstyrene dimer.
• a chain transfer agent such as dodecyl mercaptan, mercaptopropionic acid, or ⁇ -methylstyrene dimer.
• any method such as bulk polymerization, solution polymerization, emulsion polymerization, suspension polymerization, etc. can be used, depending on the purpose, use, type of structure, etc. of the polymer dispersant. It can be appropriately selected accordingly.
• the polymerization mechanism a polymerization method based on a mechanism such as radical polymerization, anionic polymerization, cationic polymerization, or coordination polymerization can be used, and various living polymerization methods capable of precisely controlling the molecular weight can also be used.
• a method of introducing a water-soluble molecular chain as a graft chain a method of copolymerizing using a macromonomer having a polymerizable functional group at the end of the water-soluble molecular chain, or a method of polymerizing the main chain and then introducing the water-soluble molecular chain. Any method can be used, such as a method of binding and a method of extending a water-soluble molecular chain from a functional group bonded to the main chain.
• the polymer thus obtained By neutralizing (making an aqueous solution) the polymer thus obtained with a basic substance, it is possible to obtain a polymer dispersant in the white pigment dispersion of the present invention.
• the basic substance include ammonia; alkylamines such as trimethylamine and triethylamine; glycol amines such as diethanolamine and triethanolamine; cyclic amines such as morpholine and pyridine; alkali metals such as sodium hydroxide and potassium hydroxide. Hydroxides and the like can be mentioned.
• the content of the polymer dispersant in the white pigment dispersion of the present invention is preferably 20% by weight or less with respect to the predetermined white pigment contained in the white pigment dispersion. More preferably, it is 2 to 15% by weight, still more preferably 3 to 8% by weight, based on the predetermined white pigment contained in the white pigment dispersion.
• the content of the polymer dispersant can be adjusted according to the specific combination of the polymer dispersant and the predetermined white pigment.
• the solvent or the aqueous liquid as the dispersion medium in the white pigment dispersion of the present invention water or, for example, a mixture of water and a water-soluble organic solvent can be used.
• water-soluble organic solvents examples include Glycos and glycerins such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butylene glycol, polyethylene glycol, polypropylene glycol, glycerin, diglycerin, which can function as a wetting agent; Methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, 2-pyrrolidone, N-methyl-2-pyrrolidone, propylene glycol, which can function as surface tension, solubility, or drying rate modifiers.
• Glycos and glycerins such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butylene glycol, polyethylene glycol, polypropylene glycol, glycerin, diglycerin, which can function as a wetting agent; Methanol, ethanol, n-propanol
• Examples thereof include, but are not limited to, monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether, methyl ethyl ketone, ethyl acetate, and ethylene glycol monon-butyl ether.
• a water-soluble organic solvent only one kind may be used, or two or more kinds may be used in combination.
• the white pigment dispersion of the present invention is prepared by mixing, for example, at least a predetermined white pigment (at least titanium dioxide surface-treated with alumina), an aqueous liquid as a solvent or a dispersion medium, and a polymer dispersant, and glass beads, zirconia. It can be obtained by wet dispersion using a milling machine (bead mill) using beads, titania beads, or the like.
• the white pigment dispersion of the present invention preferably contains a predetermined white pigment having an average particle size of 200 to 300 nm and a maximum particle size of 1000 nm or less. It is preferable to use such a white pigment dispersion in order to obtain a white pigment ink composition capable of exhibiting the desired performance.
• the white pigment dispersion of the present invention preferably contains an antioxidant, an ultraviolet absorber, an antifoaming agent, an antiseptic and antifungal agent, etc. as an additive for the purpose of enhancing storage stability.
• the content of the additive for enhancing the storage stability of the white pigment dispersion of the present invention is preferably 5% by weight or less. It is more preferably 1% by weight or less, still more preferably 0.5% by weight or less.
• the difference between the lightness L value of the coating film due to the white pigment dispersion before the centrifugation treatment and the lightness L value of the coating film due to the supernatant liquid after the centrifugation treatment (white pigment before the centrifugation treatment).
• the value obtained by subtracting the lightness L value of the coating film by the supernatant after the centrifugation from the lightness L value of the coating film by the dispersion is less than 25, and the predetermined white pigment (at least titanium dioxide surface-treated with alumina) is contained. ) Is hard to settle and has excellent storage stability.
• the coating film component other than the white pigment dispersion or the supernatant liquid after the centrifugation treatment thereof one that becomes colorless and transparent by solidification can be used.
• This centrifugation treatment can be performed by placing the white pigment dispersion in a centrifuge tube and performing it at a relative centrifugal acceleration of 150 G for 30 minutes.
• the coating film with the white pigment dispersion before the centrifugation treatment and the coating film with the supernatant after the centrifugation treatment are made by applying an ink prepared by blending at least a resin with the white pigment dispersion of the present invention on a PET film. It can be obtained by coating with and drying.
• the ink composition of the present invention contains at least the white pigment dispersion and the resin of the present invention, and can be obtained by mixing these.
• the ink composition of the present invention can be a white ink composition containing only the predetermined white pigment in the white pigment dispersion of the present invention as a colorant, and if necessary, a white pigment other than the predetermined white pigment or It may also contain other colorants such as pigments and dyes.
• the ink composition of the present invention can be used, for example, for forming a concealing layer (particularly a white concealing layer) by printing using a printing machine such as an inkjet printing machine, forming an image or character of white or other colors, and a writing instrument. Can be used for writing by.
• the content of the white pigment dispersion of the present invention in the ink composition of the present invention may be an amount containing 5 to 20% by weight of the predetermined white pigment in the white pigment dispersion with respect to the total amount of the ink composition. , Not limited to this.
• the resin used in the ink composition of the present invention is not particularly limited and can be appropriately selected depending on the intended purpose.
• examples thereof include acrylic resin, urethane resin, polyester resin, vinyl acetate resin, styrene resin, acrylic styrene resin, silicone resin, acrylic silicone resin, butadiene resin, styrene-butadiene resin, vinyl chloride resin, and the like, and are water-soluble. It does not matter whether it is a type, self-emulsifying type, or emulsion type. In addition to using only one type of resin, two or more types may be used in combination.
• the ink composition of the present invention may contain an aqueous liquid as a solvent or a dispersion medium in addition to the aqueous liquid as a solvent or a dispersion medium in the white pigment dispersion of the present invention.
• an aqueous liquid water or, for example, a mixture of water and a water-soluble organic solvent can be used.
• water-soluble organic solvents examples include Glycos and glycerins such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butylene glycol, polyethylene glycol, polypropylene glycol, glycerin, diglycerin, which can function as a wetting agent; Methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, t-butanol, 2-pyrrolidone, N-methyl-2-pyrrolidone, propylene glycol, which can function as surface tension, solubility, or drying rate modifiers.
• Glycos and glycerins such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, butylene glycol, polyethylene glycol, polypropylene glycol, glycerin, diglycerin, which can function as a wetting agent; Methanol, ethanol, n-propanol
• Examples thereof include, but are not limited to, monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether, methyl ethyl ketone, ethyl acetate, and ethylene glycol monon-butyl ether.
• a water-soluble organic solvent for example, the same or different liquid as the aqueous liquid in the white pigment dispersion of the present invention can be appropriately selected depending on the purpose, and only one type is used, or two or more types are used. It can also be used together.
• the ink composition of the present invention has a cross-linking agent, a plasticizer, a surfactant, a leveling agent, a defoaming agent, an antiseptic and antifungal agent, an ultraviolet absorber, and an antioxidant, if necessary, for the purpose of improving the desired ink performance. It can contain additives such as agents and pH adjusters.
• the content of the additive in the ink composition of the present invention is preferably 5% by weight or less. It is more preferably 1% by weight or less, still more preferably 0.5% by weight or less.
• the ink composition of the present invention can be used as an ink for an inkjet by appropriately adjusting a resin, a solvent, an aqueous liquid as a dispersion medium, additives such as a storage stabilizer, and the like.
• the ink composition for inkjet of the present invention can be a white ink composition for inkjet containing only the predetermined white pigment in the white pigment dispersion of the present invention as a colorant, and if necessary, other than the predetermined white pigment. It may also contain a white pigment or a colorant such as another pigment or dye.
• a self-emulsifying urethane resin obtained by imparting a hydrophilic group to the end of a urethane resin and emulsifying it in water by the hydrophilic group in order to prevent clogging of the tip of the head nozzle is used. Suitable.
• the self-emulsifying urethane resin has a finer particle size than the emulsion type, is less likely to cause film tension, is suitable for continuous printing with an inkjet printing machine, and has excellent long-term storage stability.
• an aliphatic or alicyclic isocyanate is used as a raw material in order to prevent the obtained white image (for example, a concealing layer) from yellowing due to the influence of light or nitrogen oxide gas.
• a self-emulsifying urethane resin is preferable.
• the content of the self-emulsifying urethane resin in the inkjet ink composition of the present invention is 50% by weight or less in terms of fastness such as water resistance and texture. preferable. It is more preferably 30% by weight or less, still more preferably 20% by weight or less.
• the inkjet ink composition of the present invention is suitable for printing with an inkjet printing machine, and it is preferable to remove coarse particles of 1 ⁇ m or more by filtration with a filter or the like.
• the image forming method of the present invention is a method of forming an image (for example, a concealing layer or other image) by an inkjet method using the ink composition for inkjet of the present invention.
• Examples of recording media for which an image is formed by an inkjet method using the inkjet ink composition of the present invention in the image forming method of the present invention include plain paper, glossy paper, special paper, textiles, knitted fabrics, and non-woven fabrics. Examples include, but are not limited to, a penetrating medium such as cloth, a vinyl chloride resin film, a PET film, a polypropylene film, and a plastic film such as a polyethylene film.
• Image formation by the image forming method of the present invention can be performed on, for example, the entire recording medium or a required portion.
• Image formation by the inkjet method using the inkjet ink composition of the present invention according to the image forming method of the present invention can generally be performed by an inkjet printing machine.
• the inkjet printing machine used for image formation by the inkjet method using the ink composition for inkjet of the present invention uses, for example, a charge control method for ejecting ink by utilizing electrostatic attraction, and vibration pressure of a piezo element.
• Drop-on-demand method pressure pulse method
• acoustic inkjet method that uses the radiation pressure that converts an electric signal into an acoustic beam and irradiates the ink
• thermal inkjet that uses the pressure generated by heating the ink to form bubbles.
• a method or the like can be mentioned, but a drop-on-demand type printing machine is preferable.
• Examples of such a printing machine include, but are limited to, EPSON PX-V700, EPSON PM-40000PX, Mimaki TX-1600S, FUJIFILM DMP-2831, and MASTERMIND MMP8130 (all trade names). It's not a thing.
• the image forming method of the present invention shall have a pretreatment step of applying a pretreatment agent in advance to the whole or a required portion of a recording medium for which an image is formed by an inkjet method using the ink composition for inkjet of the present invention. Can be done.
• the pretreatment agent By applying the pretreatment agent to the recording medium in advance, it is possible to bring about effects such as prevention of bleeding and penetration of the inkjet ink, improvement of fastness, and prevention of discoloration.
• a pretreatment agent a flocculant, a cross-linking agent, an antioxidant, an ultraviolet absorber and the like can be appropriately used, and only one type can be used, or two or more types can be used in combination. ..
• Examples of the method of applying the pretreatment agent to the recording medium include a padding method, a coating method, a screen printing method, a spray method, and an inkjet method, which can be appropriately selected according to the physical properties of the pretreatment agent to be used and the recording medium. it can.
• the recording medium After applying the pretreatment agent to the recording medium, the recording medium is moistened with the pretreatment agent, or the recording medium is naturally dried or heat-dried, and then the ink composition for inkjet of the present invention is used.
• An image can be formed on a recording medium by an inkjet method.
• the heat drying is performed by heat-treating at least the pretreated portion of the recording medium at 100 to 180 ° C. for 10 to 180 seconds using, for example, a blower dryer or a heat press. Can be done.
• heat treatment for example, at 100 to 220 ° C. 1 is performed on the entire recording medium in which an image is formed by an inkjet method using the ink composition for inkjet of the present invention or at least a portion in which an image is formed. It is possible to have an image heat treatment step of performing (up to 10 minutes).
• the image forming method of the present invention may include a step of forming another image by the inkjet method with respect to a part or all of the image formed by the inkjet method using the ink composition for inkjet of the present invention. it can.
• the original image on which the other image is formed may be in a wet state, and may be naturally dried or after heat drying.
• the original image can be based on a white inkjet ink composition containing only a predetermined white pigment as a colorant, but the original image is not limited to this.
• the other images can be, for example, printed by color ink for inkjet, but are not limited to this.
• At least the original image or the portion where the other image is formed in the recording medium is heat-treated (for example, at 100 to 220 ° C. for 1 to 10 minutes). It can also be.
• the image forming method of the present invention shall include a post-treatment step of applying a post-treatment agent to the entire recording medium or at least a portion where an image is formed by an inkjet method using the ink composition for inkjet of the present invention. be able to.
• post-treatment agents include resins, cross-linking agents, plasticizers, surfactants, leveling agents, defoamers, antiseptic and antifungal agents, UV absorbers, antioxidants, flame retardants, fabric softeners, water repellents, etc.
• Antistatic agents and the like can be mentioned, and in addition to using only one type, two or more types can be applied.
• Examples of the method of applying the post-treatment agent include a padding method, a coating method, a screen printing method, a spray method, and an inkjet method, which can be appropriately selected according to the physical properties of the post-treatment agent to be used and the recording medium.
• heat treatment for example, at 100 to 180 ° C. for 10 to 180 seconds
• heat treatment can be applied to the entire recording medium or the portion to which the post-treatment agent is applied.
• Table 1 shows the polymer dispersants A to G used in Examples and Comparative Examples. Of these, the polymer dispersants A to D used in Examples were obtained by a known polymerization method using the monomers described in the composition column, and E to G used in Comparative Examples were It is a commercially available polymer dispersant.
• the obtained mixture was milled together with 0.3 mm diameter zirconia beads and dispersed for 1.5 hours.
• a white pigment dispersion 1 having an average particle size was obtained at 249 nm.
• the white pigment was dispersed by treating in the same manner as the white pigment dispersion 1 except that 5 parts of the dispersant B and 39.5 parts of water were used instead of 3.5 parts of the dispersant A and 41 parts of water. I got body 2.
• the white pigment was dispersed by treating in the same manner as the white pigment dispersion 1 except that 7.5 parts of the dispersant C and 37 parts of water were used instead of 3.5 parts of the dispersant A and 41 parts of water. Obtained body 3.
• the white pigment dispersion 5 was obtained by treating in the same manner as the white pigment dispersion 2 except that the white pigment dispersion 2 was replaced with.
• the ink obtained by mixing 0.5 ml of the white pigment dispersion 1 and 25 ml of the resin solution was obtained from the bar coater No.
• a colorless and transparent PET film coated with No. 4 was heat-treated at 140 ° C. for 3 minutes to dry the ink, and a coating film was obtained.
• the brightness L value of the Lab color system was measured with a color difference meter (manufactured by Konica Minolta; trade name: color difference meter CR-300), and the coating was applied with the white pigment dispersion 1 before the centrifugation treatment. Comparing the lightness L value of the film with the lightness L value of the coating film by the supernatant after the centrifugation treatment, as shown in Table 3, the difference ⁇ E (the coating film by the white pigment dispersion 1 before the centrifugation treatment) The value obtained by subtracting the lightness L value of the coating film by the supernatant after the centrifugation treatment from the lightness L value) was less than 25 (less than 10). That is, it was confirmed that the white pigment dispersion was excellent in storage stability by suppressing the precipitation of titanium dioxide.
• Table 3 shows the results of treating the white pigment dispersions 2 to 6 in the same manner as in Example 1 and measuring the brightness L value in the same manner in Examples 2 to 6, respectively.
• ⁇ E value obtained by subtracting the brightness L value of the coating film from the supernatant liquid after the centrifugation treatment from the brightness L value of the coating film using the white pigment dispersion before the centrifugation treatment
• Examples 2 and 3 are Less than 5, Examples 4 and 6 were less than 10, and Example 5 was less than 20
• the obtained white pigment ink was filled in an inkjet printing machine MMP8130 manufactured by Mastermind Co., Ltd., the white pigment ink was inkjet printed on a black cotton cloth, and then the cotton cloth was dried at 170 ° C. for 3 minutes to obtain concealment. An excellent white image was obtained.
• Example 7 when printing was performed in the same manner as in Example 7 using the white pigment ink after being left to stand, the ink was stably ejected, and a white image having excellent concealing property was obtained as in Example 7.
• the white pigment was dispersed by treating in the same manner as the white pigment dispersion 1 except that 2 parts of the dispersant E and 42.5 parts of water were used instead of 3.5 parts of the dispersant A and 41 parts of water. Body NG1 was obtained.
• the white pigment was dispersed by treating in the same manner as the white pigment dispersion 1 except that 2.5 parts of the dispersant F and 42 parts of water were used instead of 3.5 parts of the dispersant A and 41 parts of water. Body NG2 was obtained.
• Table 4 shows the results of treating the white pigment dispersions NG1 to NG4 in the same manner as in Example 1 and measuring the lightness L value in the same manner in Comparative Examples 1 to 4, respectively.
• ⁇ E value obtained by subtracting the brightness L value of the coating film from the white pigment dispersion before the centrifugation treatment from the brightness L value of the coating film by the supernatant liquid after the centrifugation treatment
• 25 Comparative Examples 1 to 3
• Comparative Example 4 was 26 or more
• Titanium dioxide was easily settled, resulting in a white pigment dispersion lacking storage stability.
• a white pigment ink NG was obtained by the same treatment as in Example 7 except that the white pigment dispersion NG3 was used instead of the white pigment dispersion 1.
• the obtained white pigment ink NG was filled in an inkjet printing machine MMP8130, the white pigment ink NG was inkjet printed on a black cotton cloth in the same manner as in Example 7, and then dried at 170 ° C. for 3 minutes. , A white image with excellent concealment was obtained.
• Example 8 when the inkjet printing machine MMP8130 was filled with the white pigment ink NG left at room temperature for one week as in Example 8 and printing was performed in the same manner as in Example 7, the ink was not ejected normally and was white. No image was obtained.

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• 2019
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