Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M7/00—After-treatment of prints, e.g. heating, irradiating, setting of the ink, protection of the printed stock
  • B41M7/0081—After-treatment of prints, e.g. heating, irradiating, setting of the ink, protection of the printed stock using electromagnetic radiation or waves, e.g. ultraviolet radiation, electron beams
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41M—PRINTING, DUPLICATING, MARKING, OR COPYING PROCESSES; COLOUR PRINTING
  • B41M5/00—Duplicating or marking methods; Sheet materials for use therein
• • 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
  • C09D11/101—Inks specially adapted for printing processes involving curing by wave energy or particle radiation, e.g. with UV-curing following the printing
• • 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
  • C09D11/30—Inkjet printing inks
  • C09D11/38—Inkjet printing inks characterised by non-macromolecular additives other than solvents, pigments or dyes

Definitions

• the present invention relates to an ultraviolet-curable composition and an ultraviolet-curable ink.
• the present invention also relates to a cured product obtained by curing this ultraviolet-curable composition and a printed material obtained by curing the ultraviolet-curable ink.
• One solution is to develop water-based products. However, compared to products that use organic solvents, water-based products can produce coatings that are insufficient in terms of water resistance, solvent resistance, and hardness.
• One solution is to mix a component that cures with ultraviolet light into a water-based product to make an ultraviolet-curable composition, which is then applied and cured by irradiating it with ultraviolet light to form a coating.
• inkjet printers have features such as the ease of full colorization, low noise, ability to produce high-resolution images at low cost, high-speed printing, the ability to print on curved surfaces as well as flat surfaces, and the ease of printing on large areas. For this reason, in addition to personal use, in recent years inkjet printers have rapidly become popular for commercial use, such as for signage, window films, posters, car wrapping, wallpaper, etc.
• printing inks for commercial inkjet printers include water-based inks in which pigments are dispersed in a water-based medium; solvent UV inks in which pigments and UV-curable monomers are dispersed or dissolved in an organic solvent; solventless UV inks in which pigments are dispersed in solvent-free UV-curable monomers; water-based latex inks in which pigments and resins are dispersed in a water-based medium; and UV-curable water-based inks in which pigments and UV-curable oligomers are dispersed in a water-based medium.
• UV-curable water-based inks have a relatively good balance of all properties.
• water-based inks generally have inferior coating performance and weak coating strength, and are not suitable for large-area prints or prints for outdoor use.
• the object of the present invention is to provide an ultraviolet-curable composition and an ultraviolet-curable ink that can provide a coating film with superior coating performance, particularly excellent water resistance and solvent resistance, compared to conventional ultraviolet-curable compositions and inks.
• the present inventors have found that it is possible to realize an ultraviolet-curable composition and an ultraviolet-curable ink that provide a coating film having excellent water resistance and solvent resistance by having a radically polymerizable compound present in the form of particles and containing a specific compound as a polymerization initiator.
• the present invention has been achieved based on these findings, and has the following gist.
• a composition comprising at least a radical polymerizable compound, a polymerization initiator, and a solvent, the radical polymerizable compound is present as particles,
• the ultraviolet-curable composition according to any one of [1] to [10], further comprising a surfactant, the surfactant being a silicone-based surfactant.
• a method for producing a cured product comprising applying or printing the ultraviolet-curable composition described in any one of [1] to [11] onto a surface of a substrate, and then irradiating the substrate with active energy rays.
• a composition comprising at least a radical polymerizable compound, a polymerization initiator, a colorant, and a solvent, the radical polymerizable compound is present as particles,
• the polymerization initiator comprises a compound represented by the following formula (1):
• a method for producing a printed matter comprising applying or printing the ultraviolet-curable ink described in any one of [14] to [24] onto a surface of a substrate, and then irradiating the substrate with active energy rays.
• the UV-curable composition and UV-curable ink of the present invention provide a coating film with excellent water resistance and solvent resistance.
• the ultraviolet-curable composition of the present invention contains at least a radical polymerizable compound, a polymerization initiator, and a solvent, and the radical polymerizable compound is
• the polymerization initiator exists as particles, and is characterized in that it contains a compound represented by the following formula (1):
• the form of use of the ultraviolet-curable composition of the present invention is not particularly limited, and it can be used as a coating material, adhesive, paint, clear ink, etc.
• the ultraviolet-curable ink of the present invention can be prepared by adding a colorant described below to the ultraviolet-curable composition of the present invention.
• the colorant to be added may be one color or two or more colors. By optionally adding two or more colorants, the color of the ink can be adjusted to a desired color.
• the ultraviolet-curable ink of the present invention contains at least a radically polymerizable compound, a polymerization initiator, a colorant, and a solvent, the radically polymerizable compound being present as particles, and the polymerization initiator containing a compound represented by the following formula (1):
• the ink of the present invention is also suitable for use in inkjet printing.
• the ultraviolet-curable composition and ultraviolet-curable ink of the present invention are ultraviolet-curable, but the active energy rays used for curing are not limited to ultraviolet rays.
• the ultraviolet ray curable composition and the ultraviolet ray curable ink of the present invention are cured, they may be cured not only by active energy rays but also by heat, for example.
• the radical polymerizable compound used in the present invention may be nonionic or ionic (anionic, cationic, or amphoteric) without any particular limitation.
• the radical polymerizable compound used in the present invention being ionic like other materials or being nonionic, aggregation with other materials can be suppressed, thereby improving the storage stability of the ultraviolet curable composition or ultraviolet curable ink.
• nonionic means that, for example, the hydrophilic group of the radical polymerizable compound is composed of an ether bond or a hydroxyl group that does not undergo ionic dissociation in water.
• Ionic means, for example, that the radical polymerizable compound has a carboxy group or an amino group that can be ionically dissociated in water. More specifically, anionic radical polymerizable compounds include, for example, radical polymerizable compounds containing a carboxy group.
• the radical polymerizable compound is not particularly limited as long as it has one or more radical polymerizable groups in the molecule.
• the number of radical polymerizable groups in the molecule is preferably 2 or more, more preferably 3 or more, and on the other hand, is preferably 15 or less.
• Examples of the radically polymerizable group contained in the radically polymerizable compound include a (meth)acryloyl group, a vinyl group, a vinyl ether group, etc. Among these, a (meth)acryloyl group is preferred from the viewpoint of ease of radical polymerization.
• "(meth)acrylate” means acrylate or methacrylate. The same applies to "(meth)acryloyl".
• the radical polymerizable compound may be used alone or in combination of two or more kinds.
• the radical polymerizable compound having a radical polymerizable group with one (meth)acryloyl group in the molecule is not particularly limited.
• (meth)acrylate phenoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, isobornyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, lactone-modified flexible (meth)acrylate, t-butylcyclohexyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, glycidyl (meth)acrylate, and isobornyl (meth)acrylate.
• the radical polymerizable compound having two (meth)acryloyl groups in the molecule is not particularly limited.
• examples include triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, neopentyl glycol di(meth)acrylate, dimethylol-tricyclodecane di(meth)acrylate, bisphenol A EO (ethylene oxide) adduct di(meth)acrylate, bisphenol A PO (propylene oxide) adduct di(meth)acrylate, hydroxypivalic acid neopentyl glycol di(meth)acryl
• the radical polymerizable compound having a radical polymerizable group having three or more (meth)acryloyl groups in the molecule is not particularly limited.
• trimethylolpropane tri(meth)acrylate ethylene oxide modified trimethylolpropane tri(meth)acrylate, propylene oxide modified trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, glycerol tri(meth)acrylate, glycerol ethoxylate ...
• tri(meth)acrylate tri(meth)acrylate, glycerin propoxy tri(meth)acrylate, caprolactone-modified trimethylolpropane tri(meth)acrylate, pentaerythritol ethoxy tetra(meth)acrylate, epichlorohydrin-modified trimethylolpropane tri(meth)acrylate, tripetaerythritol octa(meth)acrylate, tetrapentaerythritol deca(meth)acrylate, polypentaerythritol poly(meth)acrylate, and caprolactone-modified dipentaerythritol hexa(meth)acrylate.
• an oligomer or polymer having one or more radically polymerizable groups in the molecule can also be used.
• an oligomer or polymer having one or more (meth)acryloyl groups in the molecule is preferred.
• the oligomer or polymer having one or more (meth)acryloyl groups in the molecule include polyester (meth)acrylate, urethane (meth)acrylate, epoxy (meth)acrylate, acrylic resin (meth)acrylate, polyether (meth)acrylate, oligo(meth)acrylate, alkyd (meth)acrylate, and polyol (meth)acrylate.
• the radically polymerizable compound used in the present invention exists as particles in the ultraviolet-curable composition or ultraviolet-curable ink.
• "existing as particles” means that when the particle size distribution is measured by dynamic light scattering using a particle size distribution meter (e.g., NANOTRAC WAVE II: manufactured by MicrotracBEL), a peak is observed in a region of particle sizes larger than 1 nm.
• NANOTRAC WAVE II manufactured by MicrotracBEL
• an amphipathic radical polymerizable compound may be used as the radical polymerizable compound.
• the amphipathic radical polymerizable compound is not particularly limited as long as it is a compound having a radical polymerizable group and a hydrophilic group.
• Examples of the amphipathic radical polymerizable compound include macromonomers or urethane (meth)acrylates having a (meth)acryloyl group or vinyl ether group as a radical polymerizable group and a polyalkylene glycol or an ionic group as a hydrophilic group, and compounds produced by reacting a polyisocyanate compound (A) described below with the following compound (B') and the following compound (C').
• Compound (B') A compound that contains a polymerizable unsaturated bond and can be bonded to the polyisocyanate compound (A).
• Compound (C') A water-soluble compound that can be bonded to the polyisocyanate compound (A).
• the structure of compound (B') that can bond with polyisocyanate compound (A) includes a hydroxyl group, a carboxyl group, and an amino group.
• polymerizable unsaturated bonds include carbon-carbon double bonds and carbon-carbon triple bonds, with carbon-carbon double bonds being preferred. More specifically, examples include carbon-carbon double bonds derived from vinyl groups, (meth)acryloyl groups, etc.
• the water-soluble compound in compound (C') includes a water-soluble polymer.
• Specific examples of the water-soluble compound in compound (C') include polyglycerin, polyhydroxy(meth)acrylate, polyamine, quaternary aminated polystyrene, sulfonated polystyrene, polyether, polyalkylene glycol, and the like. Among these, polyglycerin, polyhydroxy(meth)acrylate, and polyalkylene glycol are preferred, and polyalkylene glycol is particularly preferred. Each of these water-soluble compounds may be a copolymer.
• Compound (C') has the structure of such a water-soluble compound and a structure capable of bonding with polyisocyanate compound (A).
• the "structure capable of bonding with polyisocyanate compound (A)" is the same as that of compound (B') described above.
• Polyisocyanate compound (A), compound (B') and compound (C') may additionally have other structures.
• the polyisocyanate compound (A) is a compound having a total of two or more isocyanate groups in one molecule.
• the type of polyisocyanate compound (A) is not particularly limited, and examples include linear aliphatic polyisocyanates, aromatic polyisocyanates, and alicyclic polyisocyanates. Among these, it is preferable that the polyisocyanate compound (A) contains a polyisocyanate trimer compound from the viewpoints of weather resistance and hardness.
• a chain aliphatic polyisocyanate is a compound having a chain aliphatic structure and two or more isocyanate groups. Chain aliphatic polyisocyanates are preferred from the viewpoints of weather resistance and stretchability.
• the chain aliphatic structure in the chain aliphatic polyisocyanate is not particularly limited, but is preferably a straight-chain or branched alkylene group having 1 to 12 carbon atoms, preferably 1 to 6 carbon atoms.
• chain aliphatic polyisocyanate examples include aliphatic diisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and dimer acid diisocyanate, or trimer compounds of these polyisocyanates.
• Aromatic polyisocyanates are compounds that have an aromatic structure and two or more isocyanate groups. Aromatic polyisocyanates are preferred from the viewpoint of the strength of the cured product.
• the aromatic structure in aromatic polyisocyanates is not particularly limited, but aromatic structures having 6 to 13 carbon atoms are preferred. Examples of aromatic polyisocyanates include aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate, m-phenylene diisocyanate, and naphthalene diisocyanate, as well as trimer compounds of these polyisocyanates.
• Alicyclic polyisocyanates are compounds that have an alicyclic structure and two or more isocyanate groups.
• the alicyclic structure in the alicyclic polyisocyanate is not particularly limited, but the number of carbon atoms is usually 5 or more, preferably 6 or more, and usually 15 or less, preferably 14 or less, and more preferably 13 or less.
• the alicyclic structure is particularly preferably a cycloalkylene group.
• alicyclic polyisocyanates include diisocyanates having an alicyclic structure such as bis(isocyanatemethyl)cyclohexane, cyclohexane diisocyanate, bis(isocyanatecyclohexyl)methane, and isophorone diisocyanate, as well as trimer compounds of these polyisocyanates.
• polyisocyanate compounds (A) may be used alone or in combination of two or more.
• a polyisocyanate compound (A) a polyisocyanate having two or more structures selected from a chain aliphatic structure, an aromatic structure, and an alicyclic structure can also be used.
• polyisocyanate compound (A) those having 3 or more isocyanate groups are preferred, and those having 6 or less are preferred, particularly from the viewpoint of adhesion to a substrate.
• a trimer obtained by trimerization reaction of hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, phenylene diisocyanate, etc. is preferred, and a trimer of hexamethylene diisocyanate is particularly preferred.
• the compound (B') is a compound which contains a polymerizable unsaturated bond and can bond with the polyisocyanate compound (A).
• the compound (B') is preferably a hydroxyl group-containing (meth)acrylate, since it has excellent UV curability, fixability, water dispersion stability, solvent resistance, etc. Furthermore, the compound (B') is preferably a hydroxyl group-containing polyfunctional (meth)acrylate, since it forms a good crosslinked structure and can provide good physical properties of the cured product, such as contamination resistance and abrasion resistance.
• the number of hydroxyl groups in the hydroxyl group-containing polyfunctional (meth)acrylate (B) is preferably 3 or less, more preferably 2 or less, and even more preferably 1.
• the number of (meth)acryloyl groups in the hydroxyl group-containing polyfunctional (meth)acrylate (B) is preferably 8 or less, and more preferably 6 or less.
• Examples of the hydroxyl group-containing polyfunctional (meth)acrylate (B) include pentaerythritol tri(meth)acrylate, dipentaerythritol penta(meth)acrylate, caprolactone-modified dipentaerythritol penta(meth)acrylate, caprolactone-modified pentaerythritol tri(meth)acrylate, ethylene oxide-modified dipentaerythritol penta(meth)acrylate, ethylene oxide-modified pentaerythritol tri(meth)acrylate, 2-hydroxy-1,3-dimethacryloxypropane, 2-hydroxy-3-acryloyloxypropyl methacrylate, etc.
• hydroxyl group-containing polyfunctional (meth)acrylates (B) may be used alone or in combination of two or more.
• hydroxyl group-containing polyfunctional (meth)acrylate (B) those having one hydroxyl group and 3 to 5 (meth)acryloyl groups are preferred, particularly from the viewpoint of the strength of the resulting cured product.
• dipentaerythritol penta(meth)acrylate and pentaerythritol tri(meth)acrylate are preferred.
• Dipentaerythritol penta(meth)acrylate is particularly preferred, as it forms a good crosslinked structure and increases the mechanical strength of the cured film.
• the compound (C') is a water-soluble compound capable of bonding with the polyisocyanate compound (A).
• examples of the compound (C') include water-soluble polymers, and among these, polyalkylene glycol (C) is particularly preferred.
• the polyalkylene glycol (C) is preferably, but not limited to, a mono-substituted structure. That is, one of the hydroxyl groups of the glycol is preferably substituted.
• the substituted structure is preferably a structure that does not bond with an isocyanate.
• the polyalkylene glycol (C) may be a mixture of a compound having a mono-substituted structure and a compound not having a mono-substituted structure.
• the molecular weight of the polyalkylene glycol (C) (if it is not a single molecule, this means the number average molecular weight) is not limited, but is usually 100 or more, preferably 200 or more, and usually 5000 or less, preferably 2000 or less.
• polyalkylene glycols (C) polyalkylene glycol mono-substituted ethers are preferred.
• polyalkylene glycol mono-substituted ethers polyalkylene glycol mono-substituted ethers that do not contain ionic substituents in the ether portion are more preferred. For example, those represented by the following formula (3) are even more preferred.
• Alk is preferably an alkylene group having 1 to 3 carbon atoms, and among these, an ethylene group, a trimethylene group, or a propylene group is more preferable, and from the viewpoint of storage stability, an ethylene group is even more preferable.
• J is preferably a (meth)acryloyl group, an allyl group, or an acyl group, and more preferably an allyl group.
• g is usually 2 or more, preferably 5 or more, more preferably 6 or more, from the viewpoint of the strength of the resulting cured product, and is usually 500 or less, preferably 100 or less, more preferably 50 or less.
• polyalkylene glycols (C) may be used alone or in combination of two or more.
• the polyalkylene glycols (C) may be a mixture of compounds with different molecular weights (compounds with different g in the formula (3) above).
• the weight average molecular weight in terms of polystyrene measured by gel permeation chromatography is preferably 1,000 or more, more preferably 2,000 or more, and is preferably 100,000 or less, more preferably 50,000 or less.
• the radical polymerizable compound is present as particles.
• the particles preferably have an average particle size of 10 nm or more and 250 nm or less, and more preferably 20 nm or more and 200 nm or less.
• the average particle size of the radical polymerizable compound is within the above range, the dispersion stability is good.
• the average particle size of the radically polymerizable compound is, for example, the volume average particle size (D 50 ) measured by a particle size measuring device using a dynamic light scattering method.
• the average particle size of the radical polymerizable compound particles in the aqueous dispersion of the radical polymerizable compound is measured, and the average particle size of the radical polymerizable compound particles in this aqueous dispersion is substantially equal to the average particle size of the radical polymerizable compound particles in the ultraviolet curable composition and the ultraviolet curable ink.
• the above average particle size of the radical polymerizable compound means the particle size (primary particle size) of the radical polymerizable compound particles.
• the ultraviolet curable ink of the present invention contains a colorant.
• a colorant used in the ultraviolet-curable ink of the present invention, various dyes or pigments known as colorants used in inks can be used. From the viewpoints of irradiation with ultraviolet light and long-term storage durability of printed images, it is preferable to use a pigment as the colorant.
• the dyes that can be used in the present invention are not particularly limited, and examples thereof include water-soluble dyes such as acid dyes, direct dyes, and reactive dyes, disperse dyes, etc. Among these, anionic dyes are preferred.
• Water-soluble dyes examples include azo dyes, methine dyes, azomethine dyes, xanthene dyes, quinone dyes, phthalocyanine dyes, triphenylmethane dyes, diphenylmethane dyes, etc. Specific examples of the dyes are shown below, but the dyes are not limited to these examples.
• ⁇ C.I. Reactive Yellow> 2, 3, 7, 15, 17, 18, 22, 23, 24, 25, 27, 37, 39, 42, 57, 69, 76, 81, 84, 85, 86, 87, 92, 95, 102, 105, 111, 125, 135, 136, 137, 142, 143, 145, 151, 160, 161, 165, 167, 168, 175, 176 ⁇ C.I.
• the pigment conventionally known organic and inorganic pigments can be used.
• the pigment include azo pigments such as azo lakes, insoluble azo pigments, condensed azo pigments, and chelate azo pigments; polycyclic pigments such as phthalocyanine pigments, perylene and perylene pigments, anthraquinone pigments, quinacridone pigments, dioxandine pigments, thioindigo pigments, isoindolinone pigments, and quinophthaloni pigments; dye lakes such as basic dye lakes and acid dye lakes; organic pigments such as nitro pigments, nitroso pigments, aniline black, and daylight fluorescent pigments; and inorganic pigments such as carbon black, titanium oxide, and iron oxide pigments.
• Anionic pigments are preferred as the pigment.
• organic pigments Specific examples of organic pigments are given below.
• These dyes or pigments may be used alone or in combination of two or more.
• the ultraviolet ray curable composition and ultraviolet ray curable ink of the present invention contain a solvent.
• the solvent preferably contains water, and more preferably further contains a water-soluble organic solvent. That is, the solvent used in the present invention is more preferably a mixture of water and a water-soluble organic solvent.
• Water-soluble organic solvents are classified into two types: those that function as moisturizing solvents to increase moisture retention and wettability, and those that are used as aqueous media to adjust viscosity, improve handling, and improve ejection properties in inkjet printing. There is no clear distinction between the two, and water-soluble organic solvents used as moisturizing solvents also function as solvents.
• a water-soluble organic solvent refers to a compound that is soluble in water.
• solubility in water there are no limitations on the solubility in water, but compounds that can dissolve in water at any ratio are preferred.
• a compound is difficult to have the properties of a solvent on its own (for example, a compound that is solid or has high viscosity at room temperature), it is included in the water-soluble organic solvent as long as it can be used as a solvent by being mixed uniformly with water.
• water-soluble organic solvents include polyhydric alcohols, ethers such as polyhydric alcohol alkyl ethers and polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, and sulfur-containing compounds.
• water-soluble organic solvent examples include ethylene glycol, diethylene glycol, 1,2-propanediol (propylene glycol), 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 3-methyl-1,3-butanediol, triethylene glycol, polyethylene glycol, polypropylene glycol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, and the like.
• polyhydric alcohols such as hexanediol, 1,2-hexanediol, 1,6-hexanediol, 1,3-hexanediol, 2,5-hexanediol, 1,5-hexanediol, glycerin, 1,2,6-hexanetriol, 2-ethyl-1,3-hexanediol, ethyl-1,2,4-butanetriol, 1,2,3-butanetriol, 2,2,4-trimethyl-1,3-pentanediol, and petriol; ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, polyhydric alcohol alkyl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether; nitrogen-containing heterocyclic compounds such as 2-pyrrolidone, N-methyl-2-pyrrolidone, N-hydroxyeth
• an organic solvent with a boiling point of 250°C or less, as this not only functions as a moisturizing solvent but also provides good drying properties.
• polyol compounds having 8 or more carbon atoms and glycol ether compounds are also preferably used.
• polyol compounds having 8 or more carbon atoms include 2-ethyl-1,3-hexanediol and 2,2,4-trimethyl-1,3-pentanediol.
• glycol ether compound examples include polyhydric alcohol alkyl ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoisobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl ether; and polyhydric alcohol aryl ethers such as ethylene glycol monophenyl ether and ethylene glycol monobenzyl ether.
• polyhydric alcohol alkyl ethers such as ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, diethylene glycol monoisobutyl ether, tetraethylene glycol monomethyl ether, and propylene glycol monoethyl
• These water-soluble organic solvents may be used alone or in combination of two or more.
• the polymerization initiator used in the present invention is preferably a photoradical polymerization initiator that generates radicals as active species by the energy of light (ultraviolet rays) received by irradiation with ultraviolet rays, and initiates photopolymerization of the radically polymerizable compound, thereby curing the ultraviolet-curable composition or ultraviolet-curable ink.
• a photoradical polymerization initiator that generates radicals as active species by the energy of light (ultraviolet rays) received by irradiation with ultraviolet rays, and initiates photopolymerization of the radically polymerizable compound, thereby curing the ultraviolet-curable composition or ultraviolet-curable ink.
• the polymerization initiator may be dissolved in the solvent in a state where it is not encapsulated in the particles of the radical polymerizable compound, or may be contained in the solvent in a state where it is encapsulated in the particles of the radical polymerizable compound, or may be contained in both of these states. Since the hardness of the coating film can be improved by increasing the blending amount of the polymerization initiator, it is preferable to dissolve the polymerization initiator in the solvent rather than to include the polymerization initiator in the particles of the radical polymerizable compound.
• the ultraviolet ray curable composition and ultraviolet ray curable ink of the present invention contain a compound represented by the following formula (1) as a polymerization initiator.
• the ultraviolet ray curable composition and ultraviolet ray curable ink of the present invention preferably contain two or more types of polymerization initiators.
• containing two or more polymerization initiators means containing a compound represented by the following formula (1) and a compound other than the compound represented by the following formula (1) as a polymerization initiator. Therefore, the ultraviolet-curable composition and ultraviolet-curable ink of the present invention may contain only one type of compound represented by the following formula (1), or may contain two or more types. However, even when containing two or more types of compounds represented by the following formula (1), it is preferable that they contain one or more polymerization initiators other than the compound represented by the following formula (1).
• the compound represented by formula (1) has at least one deprotonated anionic functional group.
• the deprotonated anionic functional group is an electron-withdrawing group, and it is considered that the initiation efficiency of the initiator is increased and the compound can absorb ultraviolet light of a longer wavelength when used as a polymerization initiator by having the electron-withdrawing group in the structure of the compound, which is advantageous for curing.
• a sufficient amount of radicals can be generated in the ultraviolet-curable composition and ultraviolet-curable ink, and the coating film performance, particularly the water resistance and solvent resistance, of the cured product and printed product becomes good.
• the compound represented by formula (1) is water-soluble, and therefore can be dissolved in an aqueous medium (water and/or a water-soluble organic solvent) in an ultraviolet-curable composition or ink.
• the compound represented by formula (1) is sensitive to long-wavelength ultraviolet light, and therefore can be cured using long-wavelength ultraviolet light of 350 to 400 nm.
• the maximum absorbance of the compound represented by formula (1) is preferably 0.01 or more, more preferably 0.1 or more, even more preferably 0.5 or more, and particularly preferably 1.0 or more in the wavelength region of 350 nm to 400 nm.
• the absorbance can be determined by preparing a solution in which the compound represented by formula (1) is dissolved in a solvent capable of dissolving the compound (1) in the solvent (e.g., water) so as to have a mass concentration of 0.01%, and using a spectrophotometer (e.g., U4000 (manufactured by Hitachi High-Tech Corporation)).
• a solvent capable of dissolving the compound (1) in the solvent e.g., water
• a spectrophotometer e.g., U4000 (manufactured by Hitachi High-Tech Corporation)
• the molecular weight of the compound represented by the formula (1) is not particularly limited, but is preferably 100 or more, more preferably 200 or more, even more preferably 300 or more, and particularly preferably 400 or more.
• the molecular weight of the compound represented by the formula (1) is preferably 5000 or less, and particularly preferably 1000 or less.
• R 1 to R 8 each independently represent a hydrogen atom or a substituent, provided that at least one of R 1 to R 8 is Q 1 - , which represents a deprotonated anionic functional group.
• substituent include, but are not limited to, alkyl groups such as a methyl group and an ethyl group, alkanol groups such as a methylol group and an ethylol group, alkoxy groups such as a methoxy group and an ethoxy group, halogeno groups such as a chloro group and a bromo group, a carboxyl group, an amino group, a nitro group, etc.
• a hydrogen atom or an alkanol group is preferred, and a hydrogen atom is more preferred.
• Examples of the deprotonated anionic functional group include a group containing a carboxylate group or a sulfonylate group at the terminal, a carboxylate group, a sulfonylate group, etc. Among these, a carboxylate group and a sulfonylate group are preferred, and a carboxylate group is more preferred. Furthermore, among R 1 to R 8, R 4 is preferably Q 4 - .
• Y n+ represents a counter cation, such as an alkali metal ion, an alkaline earth metal ion, an ion derived from an organic amine, or an ammonium ion.
• alkali metal ion examples include a lithium ion, a sodium ion, a potassium ion, etc.
• alkaline earth metal ion examples include a magnesium ion, a calcium ion, etc.
• Examples of the ion derived from an organic amine include a monoalkyl ammonium ion, a dialkyl ammonium ion, a trialkyl ammonium ion, a trialcohol ammonium ion, a monoalkyl dialcohol ammonium ion, a dialkyl monoalcohol ammonium ion, etc.
• alkali metal ions or ions derived from organic amines are preferred, and ions derived from organic amines are more preferred. More specifically, lithium ions, sodium ions, potassium ions, and monoalkyldialcohol ammonium ions are preferred, and N-butyldiethanol ammonium ions are more preferred.
• n represents an integer of 1 or more. Among them, an integer of 1 or more and 3 or less is preferable.
• the polymerization initiators other than the compound represented by formula (1) are not particularly limited and may be water-soluble or fat-soluble.
• thermal radical polymerization initiators may also be used.
• aromatic ketones, acylphosphine oxide compounds, aromatic onium salt compounds, organic peroxides, thio compounds (thiophenyl group-containing compounds), ⁇ -aminoalkylphenone compounds, hexaarylbiimidazole compounds, ketoxime ester compounds, borate compounds, azinium compounds, metallocene compounds, active ester compounds, compounds having a carbon-halogen bond, and alkylamine compounds can be used.
• the polymerization initiator other than the compound represented by formula (1) may be used alone or in combination of two or more kinds.
• acylphosphine oxide compounds are preferred, and among these, the use of a compound represented by the following formula (2) is more preferred, as it has high sensitivity to long-wavelength ultraviolet light and makes it easier to cure using long-wavelength ultraviolet light of 350 to 400 nm.
• the monovalent organic residue for A 1 , A 2 , and A 3 is not particularly limited, and examples thereof include an alkyl group which may have a substituent, an alkoxy group which may have a substituent, an aryl group which may have a substituent, and an aryloxy group which may have a substituent.
• the alkyl group include, but are not limited to, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a tertiary butyl group, a pentyl group, and a neopentyl group.
• the alkoxy group includes, but is not limited to, a methoxy group, an ethoxy group, a propoxy group, a butoxy group, and the like.
• the aryl group is not particularly limited as long as it has an aromatic ring structure, and examples of the aryl group include a phenyl group, a benzyl group, a 1-naphthyl group, and a 2-naphthyl group. Examples of the aryloxy group include a phenoxy group, a 1-naphthoxy group, and a 2-naphthoxy group.
• substituents include, but are not limited to, alkyl groups such as a methyl group and an ethyl group, alkanol groups such as a methylol group and an ethylol group, alkoxy groups such as a methoxy group and an ethoxy group, halogeno groups such as a chloro group and a bromo group, a carboxyl group, an amino group, and a nitro group.
• a 1 represents either a hydrogen atom or the above-mentioned monovalent organic residue, but is preferably an aryl group which may have a substituent.
• the aryl group is preferably a phenyl group, and the substituent is preferably a methyl group.
• A1 is preferably a phenyl group or a 2,4,6-trimethylphenyl group, and more preferably a 2,4,6-trimethylphenyl group.
• A2 represents any one of the above-mentioned monovalent organic residues.
• the above-mentioned monovalent organic residues preferred is any one of an optionally substituted alkyl group, an optionally substituted alkoxy group, an optionally substituted aryl group, and an optionally substituted aryloxy group.
• an aryl group which may have a substituent is preferred, a phenyl group which may have a substituent is more preferred, and an unsubstituted phenyl group is even more preferred.
• A3 represents a hydroxy group or the above-mentioned monovalent organic residue.
• A3 may be deprotonated to form a salt with a counter cation.
• the counter cation include an alkali metal ion, an alkaline earth metal ion, an ion derived from an organic amine, and an ammonium ion (NH 4 + ).
• alkali metal ion examples include a lithium ion, a sodium ion, and a potassium ion.
• the alkaline earth metal ions refer to ions of Group 2 elements (Be, Mg, Ca, Sr, Ba, Ra). Among these, magnesium ions and calcium ions are preferred from the viewpoints of safety and water solubility.
• the organic amine-derived ion means an ion derived from an organic amine other than ammonia, and specifically includes a monoalkyl ammonium ion, a dialkyl ammonium ion, a trialkyl ammonium ion, a trialcohol ammonium ion, a monoalkyl dialcohol ammonium ion, a dialkyl monoalcohol ammonium ion, and the like.
• alkali metal ions, ions derived from organic amines, and ammonium ions are preferred.
• ions derived from organic amines and ammonium ions are more preferred.
• the reason for this is believed to be as follows. If oxygen is present during polymerization, the polymerizable compound attacks the oxygen, causing the polymerization to stop. However, if the ion is an organic ion containing a nitrogen atom, such as an ion derived from an organic amine or an ammonium ion, the nitrogen atom can extract a radical, allowing the polymerization reaction to continue. This is considered to be preferable, as it allows the polymerization to proceed more smoothly and improves the water resistance and solvent resistance of the coating film that is formed.
• the counter cation of A3 is preferably a lithium ion, a sodium ion, a potassium ion, an ammonium ion, or a monoalkyldialcohol ammonium ion, more preferably a monoalkyldialcohol ammonium ion, and particularly preferably an N-butyldiethanol ammonium ion.
• A3 is preferably a hydroxy group, and among these, it is more preferable that the hydroxy group is deprotonated to form a salt with a counter cation, and the counter cation is further preferably a monoalkyldialcohol ammonium ion, and particularly preferably an N-butyldiethanol ammonium ion.
• the ultraviolet ray curable composition and ultraviolet ray curable ink of the present invention preferably contain a surfactant in order to improve the flatness of the cured product and printed product formed and to improve wettability with the substrate.
• any of nonionic surfactants such as silicone-based surfactants and fluoro-based surfactants, amphoteric surfactants, and anionic surfactants can be used.
• nonionic surfactants are preferred from the viewpoint of preventing unexpected aggregation with other components in the ink, and among nonionic surfactants, silicone-based surfactants are more preferred from the viewpoint of environmental compatibility.
• silicone-based surfactants are more preferred because silicone-based surfactants suppress aggregation of components in the ink.
• silicone surfactants there are no particular limitations on the silicone surfactants, and they can be selected appropriately depending on the purpose. Among them, those that do not decompose even at high pH are preferred, such as side-chain modified polydimethylsiloxane, both-end modified polydimethylsiloxane, one-end modified polydimethylsiloxane, and both-end modified polydimethylsiloxane. Those having a polyoxyethylene group or a polyoxyethylene polyoxypropylene group as the modifying group are particularly preferred, as they exhibit good properties as aqueous surfactants. Polyether-modified silicone surfactants can also be used as silicone surfactants, such as compounds in which a polyalkylene oxide structure has been introduced into the Si side chain of dimethylsiloxane.
• fluorine-based surfactant a compound having 2 or more and 16 or less fluorine-substituted carbon atoms is preferable, and a compound having 4 or more and 16 or less fluorine-substituted carbon atoms is more preferable.
• fluorine-based surfactant for example, perfluoroalkyl sulfonic acid compounds, perfluoroalkyl carboxylic acid compounds, perfluoroalkyl phosphate compounds, perfluoroalkyl alkylene oxide adducts, and polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in the side chain are preferable because they have low foaming properties.
• perfluoroalkyl sulfonic acid compounds for example, perfluoroalkyl sulfonic acid, perfluoroalkyl sulfonate, etc.
• perfluoroalkyl carboxylic acid compounds for example, perfluoroalkyl carboxylic acid, perfluoroalkyl carboxylate, etc.
• perfluoroalkyl phosphate compounds for example, perfluoroalkyl phosphate ester, perfluoroalkyl phosphate ester salt, etc.
• perfluoroalkyl alkylene oxide adducts for example, perfluoroalkyl ethylene oxide adducts, etc.
• polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in the side chain sulfate ester salts of polyoxyalkylene ether polymers having perfluoroalkyl ether groups in the side chain, salts of polyoxyalkylene ether polymers having perfluoroalkyl ether groups in the side chain, etc. can be mentioned.
• counter ions of the salts in these fluorosurfactants include Li, Na, K , NH4 , NH3CH2CH2OH , NH2 ( CH2CH2OH ) 2 , and NH( CH2CH2OH ) 3 .
• polyoxyalkylene ether polymer compounds having perfluoroalkyl ether groups in the side chains are more preferred because they have particularly low foaming properties, and fluorine-based surfactants represented by the following formulas (4A) and (4B) are particularly preferred.
• s is preferably an integer of 0 or more and 10 or less
• t is preferably an integer of 0 or more and 40 or less, in order to impart water solubility.
• Z is H, or C d F 2d+1 , where d is an integer of 1 to 6, or CH 2 CH(OH)CH 2 -C e F 2e+1 , where e is an integer of 4 to 6. or C f H 2f+1 , where f is an integer from 1 to 19, inclusive.
• r is an integer from 1 to 6, inclusive, and c is an integer from 4 to 14, inclusive.
• fluorosurfactant commercially available products can be used.
• commercially available products include Surflon S-111, S-112, S-113, S-121, S-131, S-132, S-141, and S-145 (manufactured by AGC Seimi Chemical Co., Ltd.); Fullard FC-93, FC-95, FC-98, FC-129, FC-135, FC-170C, FC-430, and FC-431 (manufactured by Sumitomo 3M Limited); Megafac F-470, F-1405, and F-474 (manufactured by DIC Corporation); Zonyl TBS, FSP, FSA, FSN-100, FSN, and FSO-100, Examples include FSO, FS-300, and UR (manufactured by DuPont); FT-110, FT-250, FT-251, FT-400S, FT-150, and FT-400SW (manufactured by Neos Co., Ltd.), Polyfox PF-
• amphoteric surfactants include lauryl aminopropionate, lauryl dimethyl betaine, stearyl dimethyl betaine, and lauryl dihydroxyethyl betaine.
• nonionic surfactants include polyoxyethylene alkylphenyl ethers, polyoxyethylene alkyl esters, polyoxyethylene alkylamines, polyoxyethylene alkylamides, polyoxyethylene propylene block polymers, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, acetylene alcohol derivatives, and acetylene glycol derivatives.
• anionic surfactants include polyoxyethylene alkyl ether acetates, dodecylbenzene sulfonates, laurates, and salts of polyoxyethylene alkyl ether sulfates.
• silicone surfactants there are no particular limitations on the silicone surfactants, and they can be selected appropriately depending on the purpose. Among them, polyether-modified silicone surfactants having polyoxyethylene groups or polyoxyethylene polyoxypropylene groups as modifying groups are particularly preferred because they exhibit good properties as aqueous surfactants.
• Such surfactants may be synthesized appropriately or commercially available products may be used.
• Commercially available products are available from, for example, BYK-Chemie Co., Ltd., Shin-Etsu Chemical Co., Ltd., Dow Corning Toray Co., Ltd., Nippon Emulsion Co., Ltd., Kyoeisha Chemical Co., Ltd., etc.
• the polyether-modified silicone surfactant is not particularly limited and can be selected appropriately depending on the purpose.
• it can be one in which a polyalkylene oxide structure is introduced into the Si side chain of dimethylpolysiloxane, as shown in the following formula (5).
• polyether-modified silicone surfactants can be used.
• examples of commercially available products include KF-618, KF-642, KF-643 (Shin-Etsu Chemical Co., Ltd.), SAG001, SAG002, SAG003, SAG005, SAG503, SAG008 (Nissin Chemical Co., Ltd.), EMALEX-SS-5602, SS-1906EX (Nippon Emulsion Co., Ltd.), FZ-2105, FZ-2118, FZ-2154, FZ-2161, FZ-2162, FZ-2163, FZ-2164 (Dow Corning Toray Co., Ltd.), BYK-333, BYK-347, BYK-378 (BYK-Chemie Co., Ltd.), TSF4440, TSF4452 (Momentive Performance Materials, Inc.), and the like.
• the ultraviolet-curable composition and ultraviolet-curable ink of the present invention may contain a sensitizer.
• a sensitizer When a sensitizer is present in the ultraviolet-curable composition and ultraviolet-curable ink together with a polymerization initiator, the sensitizer in the system absorbs active energy rays to become excited, and upon contact with the polymerization initiator, promotes decomposition of the polymerization initiator, thereby enabling a curing reaction with higher sensitivity.
• the sensitizer may be either oil-soluble or water-soluble. If the sensitizer is oil-soluble, it can be encapsulated in the radical polymerizable compound particles.
• sensitizers aliphatic amines, amines having aromatic groups, or cyclic amine compounds such as piperidine, alkoxyanthracene compounds, urea compounds such as o-tolylthiourea, sulfur compounds such as sodium diethylthiophosphate or soluble salts of aromatic sulfinic acids, nitrile compounds such as N,N'-disubstituted-p-aminobenzonitrile, phosphorus compounds such as tri-n-butylphosphine or sodium diethyldithiophosphate, Michler's ketone, N-nitrosohydroxylamine derivatives, oxazolidine compounds, tetrahydro-1,3-oxazine compounds, nitrogen compounds such as condensates of formaldehyde or acetaldehyde with diamines, etc. can be used.
• urea compounds such as o-tolylthiourea
• sulfur compounds such as sodium diethylthio
• sensitizers may be used alone or in combination of two or more.
• the ultraviolet-curable composition and ultraviolet-curable ink of the present invention may contain any resin component, any oligomer component, or any monomer component (collectively referred to as "other resin components"), if necessary.
• the other resin components may be encapsulated in particles of the radical polymerizable compound, may be dissolved in a solvent, or may be dispersed alone or be in a composite state with other components in the composition or ink.
• the ultraviolet-curable composition and ultraviolet-curable ink of the present invention may contain other additives, if necessary, in addition to the above-mentioned components.
• additives include known additives such as anti-fading agents, emulsion stabilizers, penetration enhancers, UV absorbers, preservatives, antifungal agents, rust inhibitors, pH adjusters, viscosity adjusters, dispersants, dispersion stabilizers, antifoaming agents, solid wetting agents, chelating agents, etc. These various additives may be added after preparation or during preparation.
• the descriptions in paragraphs 0088 to 0096 of JP-A-2010-65205 and paragraphs 0083 to 0090 of JP-A-2010-70669 can be appropriately referred to.
• the content of water in the ultraviolet curable composition and ultraviolet curable ink of the present invention is not particularly limited and can be appropriately selected depending on the purpose.
• the content of water is usually 10% by mass or more, preferably 20% by mass or more, and usually 90% by mass or less, preferably 80% by mass or less, from the viewpoint of drying property and ejection reliability of the ink.
• the content thereof (the total content of the water-soluble organic solvent used also as a moisturizing solvent and the water-soluble organic solvent used as an aqueous medium) is not particularly limited and can be appropriately selected according to the type of water-soluble organic solvent used and the purpose.
• the content of the water-soluble organic solvent is usually 10% by mass or more and usually 50% by mass or less, preferably 40% by mass or less, in terms of drying properties, ejection reliability, wettability with the substrate, etc.
• the content of propylene glycol in the ultraviolet-curable composition and ultraviolet-curable ink of the present invention is preferably 1% by mass or more, more preferably 3% by mass or more, and even more preferably 5% by mass or more, from the viewpoint of moisture retention.
• the content is preferably 30% by mass or less, more preferably 27% by mass or less, and even more preferably 25% by mass or less.
• the total solids concentration which is the components other than the solvent in the ultraviolet curable composition and ultraviolet curable ink of the present invention, is not particularly limited and can be appropriately selected depending on the purpose. From the viewpoint of coatability, the total solids concentration is adjusted to be usually 40 mass% or less, preferably 35 mass% or less. When used as an inkjet ink, from the viewpoint of drying property and ejection reliability, the total solids concentration is adjusted to be usually 5 mass% or more, preferably 7 mass% or more, more preferably 9 mass% or more, and usually 30 mass% or less, preferably 25 mass% or less, more preferably 20 mass% or less, and even more preferably 15 mass% or less.
• the ratio of water to water-soluble organic solvent (the total of the water-soluble organic solvent used as a solvent and the water-soluble organic solvent used as a moisturizing solvent) is usually 1:0.05 to 1:1.5 (mass ratio), preferably 1:0.1 to 1:1.2 (mass ratio), and more preferably 1:0.15 to 1:1.1 (mass ratio), from the viewpoint of improving drying properties and ejection properties during inkjet printing.
• the content of the radical polymerizable compound in the ultraviolet curable composition and ultraviolet curable ink of the present invention is usually 3% by mass or more, preferably 5% by mass or more, and more preferably 7% by mass or more, from the viewpoint of the performance of the cured product and printed matter obtained and ultraviolet curability.
• the content of the radical polymerizable compound is usually 20% by mass or less, preferably 15% by mass or less, and more preferably 12% by mass or less, from the viewpoint of ejection stability.
• the content of the radical polymerizable compound in the total solid content of the ultraviolet curable composition and ultraviolet curable ink of the present invention is usually 30 mass % or more, preferably 50 mass % or more, and more preferably 60 mass % or more, and is usually 95 mass % or less, preferably 90 mass % or less, and more preferably 85 mass % or less.
• the total solid content in the ultraviolet curable composition and ultraviolet curable ink of the present invention can be rephrased as the components of the cured product and printed matter formed by the ultraviolet curable composition and ultraviolet curable ink of the present invention, and the above-mentioned numerical ranges can be similarly adopted.
• the content of each component in the total solid content is approximately equal to the content of the corresponding component in the cured product and printed matter formed by the ultraviolet curable composition and ultraviolet curable ink of the present invention.
• the content of the radically polymerizable compound in the total solids content of the ultraviolet curable composition and ultraviolet curable ink of the present invention is usually 30 mass% or more, preferably 50 mass% or more, and more preferably 60 mass% or more, and usually 95 mass% or less, preferably 90 mass% or less, and more preferably 85 mass% or less, can be treated as being equivalent to the content of components derived from the radically polymerizable compound in the cured product and printed product formed by the ultraviolet curable composition and ultraviolet curable ink of the present invention being usually 30 mass% or more, preferably 50 mass% or more, and more preferably 60 mass% or more, and usually 95 mass% or less, preferably 90 mass% or less, and more preferably 85 mass% or less.
• the contents of colorants and other components described below are described below.
• the content of the colorant in the ultraviolet-curable ink of the present invention is usually 0.1% by mass or more, and preferably 1% by mass or more, from the viewpoints of improving image density, good fixability, and ejection stability, and is usually 8% by mass or less, and preferably 6% by mass or less. From a similar viewpoint, the content of the colorant in the total solid content of the ultraviolet-curable ink of the present invention is usually 1% by mass or more, preferably 5% by mass or more, and usually 40% by mass or less, preferably 30% by mass or less.
• the content of the compound represented by formula (1) in the ultraviolet curable composition and ultraviolet curable ink of the present invention is usually 0.01 mass% or more, preferably 0.03 mass% or more, more preferably 0.05 mass% or more, and usually 4 mass% or less, preferably 3 mass% or less, more preferably 1 mass% or less, and even more preferably 0.7 mass% or less.
• the curability can be increased.
• the content of the compound represented by formula (1) in the total solid content of the composition and ink of the present invention is usually 0.05 mass% or more, preferably 0.1 mass% or more, more preferably 0.3 mass% or more, and even more preferably 0.5 mass% or more, and is usually 8 mass% or less, preferably 6 mass% or less, and more preferably 5 mass% or less.
• the content ratio (mass ratio) of the compound represented by formula (1) to the radically polymerizable compound is preferably 0.001 or more, more preferably 0.003 or more, and even more preferably 0.005 or more, from the viewpoint of curability.
• this content ratio (mass ratio) is preferably 0.4 or less, more preferably 0.3 or less, and even more preferably 0.1 or less, from the viewpoint of storage stability.
• the ultraviolet curable composition and ultraviolet curable ink of the present invention contain a compound represented by the formula (2) as a polymerization initiator
• the content of the compound represented by the formula (2) in the ultraviolet curable composition and ultraviolet curable ink of the present invention can be appropriately selected depending on the required performance of the cured product to be obtained, but is usually 0.05 mass% or more, preferably 0.1 mass% or more, more preferably 0.3 mass% or more, and even more preferably 0.4 mass% or more, and is usually 8 mass% or less, preferably 5 mass% or less, more preferably 3 mass% or less, even more preferably 2 mass% or less, and particularly preferably 1 mass% or less.
• the content of the compound represented by the formula (2) being within this range, the curing speed can be sufficiently improved and the insoluble residue of the polymerization initiator and coloring derived from the polymerization initiator can be avoided.
• the content of the compound represented by formula (2) in the total solid content of the ultraviolet-curable composition and ultraviolet-curable ink of the present invention is usually 0.5 mass% or more, preferably 1 mass% or more, more preferably 2 mass% or more, even more preferably 3 mass% or more, and is usually 20 mass% or less, more preferably 15 mass% or less, even more preferably 10 mass% or less, and particularly preferably 8 mass% or less.
• the content ratio (mass ratio) of the compound represented by formula (2) to the compound represented by formula (1) in the ultraviolet curable composition and ultraviolet curable ink of the present invention is preferably 0.01 or more, more preferably 0.03 or more, and even more preferably 0.3 or more from the viewpoint of storage stability.
• this content ratio (mass ratio) is preferably 800 or less, more preferably 200 or less, and even more preferably 60 or less from the viewpoint of curability.
• the content ratio (mass ratio) of the compound represented by formula (2) to the radical polymerizable compound is preferably 0.005 or more, more preferably 0.01 or more, and even more preferably 0.03 or more, from the viewpoint of curability.
• this content ratio (mass ratio) is preferably 0.5 or less, more preferably 0.3 or less, and even more preferably 0.2 or less, from the viewpoint of 0.8.
• the total content of all polymerization initiators in the ultraviolet curable composition and ultraviolet curable ink of the present invention is usually 0.06 mass% or more, preferably 0.13 mass% or more, more preferably 0.35 mass% or more, and usually 12 mass% or less, preferably 8 mass% or less, more preferably 4 mass% or less, and even more preferably 2.7 mass% or less.
• the curability can be increased.
• the total content of all polymerization initiators in the total solid content of the ultraviolet curable composition and ultraviolet curable ink of the present invention is usually 0.55 mass% or more, preferably 1.1 mass% or more, more preferably 2.3 mass% or more, and even more preferably 3.5 mass% or more, and is usually 28 mass% or less, preferably 21 mass% or less, and more preferably 15 mass% or less.
• the content of the surfactant in the ultraviolet curable composition and ultraviolet curable ink of the present invention is usually 0.001% by mass or more, preferably 0.01% by mass or more, more preferably 0.03% by mass or more, and usually 5% by mass or less, preferably 3% by mass or less, more preferably 1% by mass or less.
• the content of the surfactant in the total solid content of the ultraviolet-curable composition and ultraviolet-curable ink of the present invention is usually 0.01 mass % or more, preferably 0.1 mass % or more, and more preferably 0.2 mass % or more, and is usually 10 mass % or less, preferably 5 mass % or less, and more preferably 3 mass % or less.
• the content thereof is usually 0.01% by mass or more, preferably 0.03% by mass or more, more preferably 0.05% by mass or more, and usually 4% by mass or less, preferably 3% by mass or less, more preferably 1% by mass or less, and even more preferably 0.7% by mass or less.
• the content of the sensitizer is within the above range, the effect of the sensitizer can be sufficiently obtained.
• the content of the sensitizer in the total solids content of the composition and ink of the present invention is usually 0.05 mass% or more, preferably 0.1 mass% or more, more preferably 0.3 mass% or more, and even more preferably 0.5 mass% or more, and is usually 8 mass% or less, preferably 6 mass% or less, and more preferably 5 mass% or less.
• the method for producing the ultraviolet curable composition and ultraviolet curable ink of the present invention includes a method of preparing a dispersion in which a radical polymerizable compound is dispersed as particles in an aqueous medium (hereinafter, sometimes referred to as a "radical polymerizable compound dispersion") and a dispersion in which a colorant such as a pigment is dispersed in an aqueous medium (hereinafter, sometimes referred to as a "colorant dispersion”), and mixing the polymerizable compound dispersion with a polymerization initiator, other additives and organic solvent, and, if necessary, the colorant dispersion. Even if a colorant is added to the ultraviolet-curable composition of the present invention, an ultraviolet-curable ink having similar properties can be obtained.
• the radical polymerizable compound dispersion liquid can be prepared by using a known method such as a high pressure emulsification method, a phase inversion emulsification method, etc.
• the radical polymerizable compound dispersion liquid can be prepared by using various known emulsifiers and dispersants as necessary within a range that does not impair the effects of the present invention.
• the high-pressure emulsification method is a method in which an aqueous phase, an oil phase, and an amphipathic substance such as a surfactant are premixed and emulsified using a high-pressure emulsifier such as a homogenizer.
• the phase inversion emulsification method is a method in which an amphipathic substance such as a surfactant is dissolved and dispersed in an oil phase, and an aqueous phase is added thereto to obtain an O/W type emulsion.
• an amphipathic substance such as a surfactant
• an aqueous phase is added thereto to obtain an O/W type emulsion.
• the solids concentration of the thus prepared radically polymerizable compound dispersion is preferably about 10% by mass or more and 40% by mass or less from the viewpoint of handleability.
• Each radically polymerizable compound may be prepared separately as a dispersion and mixed in any ratio, but it is preferable to premix the radically polymerizable compounds before preparing the dispersion.
• other components such as a non-radically polymerizable polymer, a polymerization initiator, a preservative, etc., may be premixed and then prepared into a dispersion.
• the colorant dispersion can be prepared by adding a colorant such as a pigment to a solvent such as water and mixing them.
• concentration of the colorant such as a pigment in the colorant dispersion is usually 5% by mass or more, preferably 10% by mass or more, and usually 40% by mass or less, preferably 35% by mass or less, from the viewpoints of handling and storage stability.
• the viscosity of the ultraviolet curable composition of the present invention can be adjusted according to the purpose and the form of use.
• the viscosity at 25°C is preferably 25 mPa ⁇ sec or less, more preferably 20 mPa ⁇ sec or less, and even more preferably 10 mPa ⁇ sec or less.
• the lower limit of the viscosity of the ultraviolet curable composition of the present invention is not particularly limited, but is preferably 1 mPa ⁇ sec or more, and more preferably 2 mPa ⁇ sec or more.
• the viscosity of the ultraviolet curable ink of the present invention can be adjusted as desired according to the application and mode of use.
• the viscosity at 25° C. is preferably 25 mPa ⁇ sec or less, more preferably 20 mPa ⁇ sec or less, and even more preferably 10 mPa ⁇ sec or less.
• the lower limit of the viscosity of the ultraviolet curable ink of the present invention is not particularly limited, but is preferably 1 mPa ⁇ sec or more, and more preferably 2 mPa ⁇ sec or more.
• the substrate to which the ultraviolet-curable composition and ultraviolet-curable ink of the present invention are applied is not particularly limited, and examples thereof include plastic materials such as polyesters such as polyethylene terephthalate (PET), polyolefins such as polyvinyl chloride (PVC), polyethylene (PE), and polypropylene (PP), paper, TEXTILE (cloth and fabric), leather, glass, ceramic, wood, metal, rubber, and composites thereof.
• PET polyethylene terephthalate
• PVC polyolefins
• PE polyethylene
• PE polypropylene
• TEXTILE cloth and fabric
• leather, glass, ceramic, wood, metal, rubber, and composites thereof TEXTILE
• a cured product and a printed product By curing the ultraviolet-curable composition and ultraviolet-curable ink of the present invention, a cured product and a printed product can be obtained.
• a method for obtaining a cured product and a printed matter by curing the ultraviolet curable composition or ultraviolet curable ink of the present invention a method is used in which the ultraviolet curable composition or ultraviolet curable ink is applied to a substrate using a known method such as a coater such as a spin coater or a bar coater, or various printing methods such as inkjet, and then irradiated with active energy rays.
• composition or ink is once applied to a substrate such as a film, then transferred to another substrate, and then irradiated with active energy rays.
• a pattern of the cured product or printed matter can be created by photolithography.
• the polymerization initiator containing the compound represented by the above formula (1) is decomposed by irradiation with active energy rays to generate radicals, and the polymerization reaction of the radically polymerizable compound proceeds.
• a method for curing the UV-curable composition or UV-curable ink of the present invention to obtain a cured product or printed matter a method can be used in which the UV-curable composition or UV-curable ink is applied to a substrate, the substrate is heated, and then active energy rays are irradiated.
• the heating temperature is preferably 40°C or higher, more preferably 45°C or higher, and even more preferably 50°C or higher. By carrying out the above heating, volatile components such as water can be dried, and curability tends to be further improved. There is no particular upper limit to the heating temperature.
• the heating means is not particularly limited, but examples include ceramic heaters, halogen heaters, and quartz tube heaters.
• the timing of heating may be before, during, or after the ultraviolet-curable composition or ultraviolet-curable ink of the present invention is applied to the substrate, but it is more preferable to continue heating throughout the entire process, before, during, and after application.
• UV-LEDs ultraviolet light-emitting diodes
• UV-LDs ultraviolet laser diodes
• the emission peak wavelength of the active energy ray source to be irradiated is preferably in the range of 350 to 450 nm.
• the irradiation energy is preferably 20 J/cm2 or less, for example, 0.5 to 10 J/ cm2 .
• the emission peak wavelength may be one or more within the above wavelength range.
• the irradiation of active energy rays is not limited to the above-mentioned intentional process, and may be, for example, outdoor exposure to sunlight.
• the radical polymerizable compound used in the present invention has high reactivity (curability), it is not necessary to irradiate active energy rays by heating alone. In other words, it is sufficient for the ultraviolet-curable composition or ink of the present invention to have ultraviolet curability, and it is not limited to being used in a printing method having a process of irradiating active energy rays.
• the ultraviolet-curable ink of the present invention can be contained in an ink cartridge or ink bottle, which eliminates the need to directly touch the ink during ink transport, ink replacement, and other operations, thereby preventing staining of hands, fingers, and clothing, and also prevents contamination of the ink with foreign matter such as dust.
• the shape, size, material, etc. of the ink container itself are not particularly limited as long as they are suitable for, for example, the inkjet printer to which they are applied. It is desirable that the material of the ink container is a light-shielding material that does not transmit light, or that the container is covered with a light-shielding sheet or the like.
• the ultraviolet-curable ink of the present invention can be suitably used in an ink-jet recording method.
• An inkjet recording method using the ultraviolet ray curable ink of the present invention preferably comprises a step of ejecting the ultraviolet ray curable ink of the present invention from an ejection nozzle of an inkjet printer to adhere to a substrate, a heating step of heating the substrate to which the ink is adhered, and an irradiation step of irradiating the ink adhered to the substrate with active energy rays.
• the step of applying the ultraviolet-curable ink of the present invention to a substrate is not necessarily limited to a method using an inkjet printer, as long as the ink is applied to the substrate in a mist (mist or spray) form.
• the heating temperature is preferably 120° C. or lower, and more preferably 100° C. or lower.
• the ultraviolet-curable composition and ultraviolet-curable ink of the present invention are water-based, and therefore have excellent environmental and safety properties, and while satisfying the required performance in a well-balanced manner, the cured product and printed product have excellent water resistance and solvent resistance.
• an ink When used as an ink, it has the characteristic that it can print images with high image quality and high coating performance on various substrates with high productivity, and can be used for various applications such as posters, road signs, signboards, signboards, various outdoor and indoor display boards, building materials (surface materials for exteriors, interiors, walls, floors, ceilings, windows, etc.), exteriors of vehicles (automobiles, trains, aircraft, etc.), surface materials for furniture and office automation equipment, and paper printed products.
• the radical polymerizable compound 1 was kept at 60° C., GENOPOL TX-2 manufactured by RAHN was added as a polymerization initiator A in a composition ratio shown in Table 1 below, and ion-exchanged water preheated to 60° C. was added while stirring and mixing to obtain an aqueous dispersion of the radical polymerizable compound 1.
• Inks 2 to 4 were obtained in the same manner as Ink 1, except that the types and blending ratios of the pigment dispersions and the blending ratio of polymerization initiator C were changed as shown in Table 1 below using the following pigment dispersions.
• Inks 5 to 8 were obtained in the same manner as inks 1 to 4, except that polymerization initiator A was not added.
• Irgacure 1800 manufactured by Ciba Specialty Chemicals
• Ink 10 was obtained in the same manner as ink 1, except that polymerization initiator C was not used.
• Ink 11 was obtained in the same manner as ink 9, except that polymerization initiator C was not used.
• Example 1 An illuminated PET film was used as the substrate, and ink 1 was applied to the substrate with a thickness of 15 ⁇ m over an area of approximately 50 cm2 using a bar coater. The substrate was then heated at 80° C. for 10 minutes, and then irradiated with ultraviolet light from an LED having a peak wavelength of 385 nm with an irradiation energy of 7 J/ cm2 to form a cured film.
• Illuminated PET is a non-absorbent, illuminated transparent film made of surface-treated polyethylene terephthalate.
• Examples 2 to 9, Comparative Examples 1 to 2 A cured film was obtained in the same manner as in Example 1, except that the type of ink was changed as shown in Table 2.
• ⁇ Solvent resistance evaluation> The solvent resistance was evaluated by rubbing the surface of the cured film with absorbent cotton dipped in a mixture of ethanol and water at a ratio of 3:2 (by mass) under a load of 200 g, and visually observing whether the cured film was damaged or stuck, and was evaluated according to the following evaluation criteria. In the present invention, " ⁇ " and " ⁇ " were considered to be acceptable. The results are shown in Table 2.
• the cured films for which the water resistance was evaluated as ⁇ were not subjected to the solvent resistance test. ⁇ : The cured film was not damaged and the cured film did not adhere to the absorbent cotton. ⁇ : The cured film was slightly damaged, and some of the cured film adhered to the absorbent cotton. ⁇ : Damage to the cured film or adhesion of the cured film to the absorbent cotton. -: Solvent resistance test not performed.
• the ultraviolet-curable ink of the present invention which contains the compound represented by the formula (1) as a polymerization initiator, can give a coating film having good water resistance and also good solvent resistance.
• Comparative Examples 1 and 2 which do not contain the compound represented by formula (1) as the polymerization initiator, it was found that the coating film performance was inferior.
• the ultraviolet-curable ink of the present invention can be prepared by adding a colorant to the ultraviolet-curable composition of the present invention. It is considered that even an ultraviolet-curable composition to which no colorant is added can provide the same effects as the ultraviolet-curable inks shown in the examples.

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• 2024
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