Pigment dispersion for active energy ray-curable inks, and active energy ray-curable inks

Abstract

To provide a pigment dispersant allowing preparation of a pigment dispersion having good long-term storage stability while being capable of inhibiting aggregation of C.I. Pigment Orange 43 in a more convenient manner.SOLUTION: For example, the present invention provides at least one pigment dispersant selected from the group consisting of compounds represented by formula (1) in the figure and their metal salts, ammonium salts, organic amine salts and salts of organic quaternary ammonium compounds. (In formula (1), R1 to R4 each independently represent a hydrogen atom, an alkyl group, an alkoxy group, a hydroxyl group or a halogen atom, and n represents a number from 0.5 to 3.)SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a pigment dispersant, a pigment dispersion, and a coating agent.

Background Art

[0002] Generally, when dispersing pigments in vehicles such as paints, gravure inks, offset inks, inks for writing instruments, and inkjet inks, it is difficult to stably disperse the pigments in the vehicle, and the dispersed fine pigment particles tend to aggregate in the vehicle. As a result, problems such as an increase in viscosity, a decrease in coloring power and gloss, etc. may occur.

[0003] In recent years, due to its simple and inexpensive characteristics in inkjet image forming methods, the development of commercial printing equipment and industrial printing equipment has been underway. For example, so-called sign applications such as outdoor billboards fall into this category. In this case, high weather resistance and wide color reproducibility outdoors are required. To achieve these, in addition to inks of each color of yellow, magenta, cyan, and black, an inkjet using an ink containing C.I. Pigment Orange 43 (hereinafter, may be referred to as "Pigment Orange 43") having relatively high weather resistance as a feature has been proposed (Patent Documents 1 to 3).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] A tendency for pigment orange 43 to aggregate in the vehicle has also been confirmed. Therefore, dispersions containing pigment orange 43 have low storage stability, and if the dispersion is stored for a long period of time, thickening of the dispersion and generation of foreign matter are observed. These can cause clogging of the nozzles that dispense coating agents such as ink containing the dispersion, leading to problems such as nozzle failure. As a solution to this problem, Patent Document 3 proposes incorporating glycol ether with a flash point of 70°C or less into the ink. According to Patent Document 3, it is presumed that the glycol ether can suppress the rise in moisture content during long-term storage of the ink, thereby suppressing the aggregation of pigment orange 43. However, this method requires dehydrating solvents beforehand, and care must also be taken to prevent moisture absorption during the ink manufacturing process.

[0006] In view of the above-mentioned prior art, the present invention aims to provide a pigment dispersant that can suppress the aggregation of pigment orange 43 more easily without a dehydration step and can also prepare a pigment dispersion with good long-term storage stability. [Means for solving the problem]

[0007] The present invention provides a pigment dispersant for CI Pigment Orange 43, which is at least one CI Pigment Orange 43 derivative selected from the group consisting of compounds represented by the following general formula (1), compounds represented by the following general formula (2), and their metal salts, ammonium salts, organic amine salts, and salts of organic quaternary ammonium compounds.

[0008] TIFF0007867458000001.tif78170(In general formula (1), R1 to R4 each independently represent a hydrogen atom, an alkyl group, an alkoxy group, a hydroxyl group, or a halogen atom, and in general formulas (1) and (2), n independently represents a number from 0.5 to 3.) [Effects of the Invention]

[0009] According to the present invention, it is possible to provide a pigment dispersant that can suppress the aggregation of pigment orange 43 and prepare a pigment dispersion with good long-term storage stability. [Modes for carrying out the invention]

[0010] The following describes embodiments of the present invention, but the present invention is not limited to the following embodiments.

[0011] <Pigment dispersant> A pigment dispersant of one embodiment of the present invention (hereinafter sometimes simply referred to as "pigment dispersant") is a pigment dispersant for CI Pigment Orange 43. That is, this pigment dispersant is used to disperse Pigment Orange 43. This pigment dispersant is at least one CI Pigment Orange 43 derivative (hereinafter sometimes referred to as "pigment orange 43 derivative") selected from the group consisting of compounds represented by the following general formula (1), compounds represented by the following general formula (2), and their metal salts, ammonium salts, organic amine salts, and salts of organic quaternary ammonium compounds.

[0012] <Pigment dispersion> Furthermore, a pigment dispersion according to one embodiment of the present invention (hereinafter sometimes simply referred to as "pigment dispersion") contains a liquid medium, CI pigment orange 43, and a pigment dispersant. The above-mentioned pigment dispersant can be used in this pigment dispersion. That is, the pigment dispersant in the pigment dispersion contains at least one CI pigment orange 43 derivative selected from the group consisting of compounds represented by the following general formula (1), compounds represented by the following general formula (2), and their metal salts, ammonium salts, organic amine salts, and organic quaternary ammonium compounds.

[0013] TIFF0007867458000002.tif39170

[0014] TIFF0007867458000003.tif41170

[0015] In the above general formula (1), R1 to R4 each independently represent a hydrogen atom, an alkyl group, an alkoxy group, a hydroxyl group, or a halogen atom, and in the above general formulas (1) and (2), n independently represents a number from 0.5 to 3.

[0016] The pigment dispersion of this embodiment contains a pigment dispersant which is a specific pigment orange 43 derivative, and therefore it is possible to suppress the aggregation of pigment orange 43 and has good long-term storage stability. Therefore, by using the pigment dispersant of this embodiment which is a specific pigment orange 43 derivative, it is possible to prepare a pigment dispersion that can suppress the aggregation of pigment orange 43 and has good long-term storage stability. The components and characteristics of the pigment dispersion will be described in detail below.

[0017] (Pigment Orange 43) The pigment dispersion contains pigment orange 43. In the pigment dispersion, pigment orange 43 may be dispersed in the liquid medium by the pigment dispersant of this embodiment.

[0018] Pigment Orange 43 is a pigment with CAS registry number 4424-06-0. The chemical name of Pigment Orange 43 is bisbenzimidazol[2,1-b:2',1'-i]benzo[lmn][3,8]phenanthroline-8,17-dione, or 1,8-(1H-benzimidazole-2,1-diylcarbonyl)-5,4-(1H-benzimidazole-2,1-diylcarbonyl)naphthalene. Pigment Orange 43 has a penoline structure and is a vivid reddish-orange in hue.

[0019] The volume average particle diameter of Pigment Orange 43 contained in the pigment dispersion is preferably 80 nm or more and 400 nm or less, more preferably 90 nm or more and 350 nm or less, and still more preferably 100 nm or more and 300 nm or less. Even when Pigment Orange 43 having different volume average particle diameters is mixed and used, the volume average particle diameter of each Pigment Orange 43 is preferably within the above range. When the volume average particle diameter of Pigment Orange 43 is within the above range, the dispersion stability is good, and when the pigment dispersion is contained in a coating agent such as ink, the ejection property and the weather resistance of the coating film are more likely to be good. From the viewpoint of storage stability, the volume average particle diameter of Pigment Orange 43 is preferably 80 nm or more, more preferably 90 nm or more, and still more preferably 100 nm or more. On the other hand, from the viewpoint of suppressing nozzle clogging and the like, that is, from the viewpoint of ejection property, the volume average particle diameter of Pigment Orange 43 is preferably 400 nm or less, more preferably 350 nm or less, and still more preferably 300 nm or less.

[0020] In this specification, the volume average particle diameter of Pigment Orange 43 is the particle diameter (median diameter; D 50 ) that becomes 50% cumulative in the volume-based particle size distribution measured by the dynamic light scattering method. For the measurement of the volume average particle diameter of Pigment Orange 43, a particle size distribution measuring device using the dynamic light scattering method (for example, the product name "FPAR-1000" manufactured by Otsuka Electronics Co., Ltd.) can be used.

[0021] The content of Pigment Orange 43 in the pigment dispersion is preferably 1% by mass or more and 90% by mass or less based on the total mass of the pigment dispersion. When the content of Pigment Orange 43 is within the above range, sufficient color development property is easily obtained, and the dispersion stability is easily enhanced. From the viewpoint of color development property, the above content of Pigment Orange 43 is preferably 1% by mass or more, more preferably 5% by mass or more, still more preferably 10% by mass or more, and even more preferably 15% by mass or more. On the other hand, from the viewpoint of dispersion stability, the above content of Pigment Orange 43 is preferably 90% by mass or less, more preferably 70% by mass or less, still more preferably 50% by mass or less, and even more preferably 30% by mass or less.

[0022] The pigment dispersion may contain a colorant such as a pigment other than Pigment Orange 43, but the ratio of Pigment Orange 43 to the total mass of the colorant is preferably 50% by mass or more, more preferably 70% by mass or more, and still more preferably 90% by mass or more. Thus, it is preferable to use Pigment Orange 43 as the main component of the colorant and use the pigment dispersion as an orange pigment dispersion.

[0023] (Pigment Orange 43 derivative) The pigment dispersion contains, as a pigment dispersant, at least one Pigment Orange 43 derivative selected from the group consisting of a compound represented by the following general formula (1), a compound represented by general formula (2), and salts thereof, ammonium salts, organic amine salts, and organic quaternary ammonium compound salts (hereinafter, various salts may be collectively simply referred to as "salts"). In the pigment dispersion, the Pigment Orange 43 derivative has a role as a dispersant for dispersing Pigment Orange 43 in the liquid medium.

[0024] TIFF0007867458000004.tif56170

[0025] TIFF0007867458000005.tif60170

[0026] In general formula (1), R1, R2, R3, and R4 each independently represent a hydrogen atom, an alkyl group, an alkoxy group, a hydroxyl group, or a halogen atom. In general formulas (1) and (2), n independently represents a number between 0.5 and 3.

[0027] The alkyl and alkoxy groups that R1 to R4 in general formula (1) can be linear or branched. The number of carbon atoms in the alkyl and alkoxy groups is preferably 1 to 6, more preferably 1 to 4, and even more preferably 1 to 3. Methyl, ethyl, n-propyl, or isopropyl groups are more preferred as alkyl groups. Methoxy, ethoxy, n-propoxy, or isopropoxy groups are even more preferred as alkoxy groups. Examples of halogen atoms that R1 to R4 in general formula (1) can be include fluorine, chlorine, bromine, and iodine atoms.

[0028] The structural formula (1A) on the left side of general formula (1) corresponds to the structure of Pigment Orange 43. The compound represented by general formula (1) is a compound in which an average of n substituted benzyl groups, each having at least one sulfone group (SO3H) as a substituent, represented by the structural formula (1B) on the right side of general formula (1), are introduced into the structure corresponding to Pigment Orange 43. In other words, n in general formula (1) represents the average number of groups represented by structural formula (1B) introduced into the structure corresponding to Pigment Orange 43. The bond position of the group represented by structural formula (1B) in the compound represented by general formula (1) is the aromatic ring in the structure corresponding to Pigment Orange 43. Therefore, the compound represented by general formula (1) is a Pigment Orange 43 derivative in which an average of n of the 12 hydrogen atoms in the structure of Pigment Orange 43 are replaced by the group represented by the above structural formula (1B) as a substituent.

[0029] Furthermore, the structural formula (2A) on the left side of general formula (2) also corresponds to the structure of Pigment Orange 43. The compound represented by general formula (2) is a compound in which an average of n groups having a sulfophenyl-pyrazolone ring, represented by the structural formula (2B) on the right side of general formula (2), are introduced into the structure corresponding to Pigment Orange 43. In other words, n in general formula (2) represents the average number of groups represented by structural formula (2B) introduced into the structure corresponding to Pigment Orange 43. The bond position of the group represented by structural formula (2B) in the compound represented by general formula (2) is the aromatic ring in the structure corresponding to Pigment Orange 43. Therefore, the compound represented by general formula (2) is a Pigment Orange 43 derivative in which an average of n of the 12 hydrogen atoms in the structure of Pigment Orange 43 are replaced by the group represented by the above structural formula (2B) as a substituent.

[0030] Compounds represented by general formula (1) or (2) (pigment orange 43 derivatives) can be synthesized, for example, by the following method. First, pigment orange 43 is added to concentrated sulfuric acid at a temperature of 30°C or lower, paraformaldehyde is added, and the mixture is reacted at 40-70°C, preferably 50-60°C. Then, a benzenesulfonic acid derivative or a sulfophenyl-2-pyrazolin-5-one derivative is added, and the mixture is reacted at 60-100°C, preferably 70-80°C, to obtain a compound represented by general formula (1) or (2) (pigment orange 43 derivative). Alternatively, when isolating and purifying the obtained compound represented by general formula (1) or (2), salts of the compound represented by general formula (1) or (2) can be obtained by salting out using the salts that constitute the salts described above.

[0031] Pigment Orange 43 derivatives may be metal salts, ammonium salts, organic amine salts, or salts of organic quaternary ammonium compounds represented by the general formula (1) or (2) described above. Examples of metals constituting the metal salts include alkali metals such as lithium, sodium, and potassium; and polyvalent metals such as calcium, barium, aluminum, manganese, strontium, magnesium, and nickel. Examples of organic amines constituting the organic amine salts include trimethylamine, triethylamine, dimethylaminoethanol, and triethanolamine. Examples of quaternary ammonium compounds constituting the salts of organic quaternary ammonium compounds include tetramethylammonium, tetraethylammonium, tetrapropylammonium, tetrabutylammonium, benzyltrimethylammonium, benzyltriethylammonium, and dimethyldioctadecylammonium.

[0032] Examples of compounds represented by general formula (1) include those represented by structural formulas (1-1) to (1-6) below. Examples of compounds represented by general formula (2) include those represented by structural formulas (2-1) and (2-2) below. At least one CI pigment orange 43 derivative selected from the group consisting of the compounds represented by structural formulas (1-1) to (1-6), (2-1) and (2-2) below, and their salts, is preferred.

[0033] TIFF0007867458000006.tif41170

[0034] TIFF0007867458000007.tif39170

[0035] TIFF0007867458000008.tif41170

[0036] TIFF0007867458000009.tif41170

[0037] TIFF0007867458000010.tif37170

[0038] TIFF0007867458000011.tif39170

[0039] TIFF0007867458000012.tif41170

[0040] TIFF0007867458000013.tif39170

[0041] As a result of our investigations, we found that among pigment orange 43 derivatives, at least one CI pigment orange 43 derivative selected from the group consisting of compounds represented by structural formulas (1-1), (1-2), and (2-1), respectively, and their salts, is even more effective in stabilizing the dispersion of pigment orange 43. Therefore, it is even more preferable for the pigment dispersion to contain, as a pigment dispersant, at least one CI pigment orange 43 derivative selected from the group consisting of compounds represented by structural formulas (1-1), (1-2), and (2-1), respectively, and their metal salts, ammonium salts, organic amine salts, and salts of organic quaternary ammonium compounds.

[0042] The content of pigment orange 43 derivative in the pigment dispersion is preferably 0.05% by mass or more and 40% by mass or less relative to the content of pigment orange 43 in the pigment dispersion. Having the content of pigment orange 43 derivative relative to the content of pigment orange 43 within the above range makes it easier to obtain a pigment dispersion with good weather resistance and even better storage stability. From these viewpoints, the content of pigment orange 43 derivative relative to the content of pigment orange 43 is more preferably 0.1% by mass or more and 30% by mass or less, even more preferably 0.5% by mass or more and 20% by mass or less, and even more preferably 1% by mass or more and 10% by mass or less. The content of pigment orange 43 derivative relative to the content of pigment orange 43 can be determined from the content of pigment orange 43 P and the content of pigment orange 43 derivative B in the pigment dispersion using the formula [B / P] × 100 (mass%).

[0043] As long as the content of pigment orange 43 derivative relative to the content of pigment orange 43 is within the above range, the content of pigment orange 43 derivative relative to the total mass of the pigment dispersion is not particularly limited. Preferably, the content of pigment orange 43 derivative is 0.0005% by mass or more and 36% by mass or less relative to the total mass of the pigment dispersion. More preferably, the content of pigment orange 43 derivative relative to the total mass of the pigment dispersion is 0.0025% by mass or more, even more preferably 0.005% by mass or more, and even more preferably 0.0075% by mass or more. On the other hand, it is more preferably, the content of pigment orange 43 derivative relative to the total mass of the pigment dispersion is 28% by mass or less, even more preferably 20% by mass or less, and even more preferably 12% by mass or less.

[0044] (liquid medium) The pigment dispersion contains a liquid medium. In the pigment dispersion, the liquid medium acts as a dispersion medium for pigment orange 43. The liquid medium can be one that takes the form of a liquid at room temperature (20°C ± 15°C).

[0045] The liquid medium is not particularly limited, and an appropriate liquid medium can be selected and used depending on the application in which the pigment dispersion is used. For example, when the pigment dispersion is used in solvent-type inks (oil-based inks) as a colorant for gravure inks, paints, and color filters, an organic solvent can be suitably used as the liquid medium. Also, when the pigment dispersion is used in active energy ray-curable inks such as UV-curable inks and electron beam-curable inks as a colorant for active energy ray-curable inkjet inks, a polymerizable compound can be suitably used as the liquid medium. The liquid medium preferably contains at least one selected from the group consisting of organic solvents and polymerizable compounds. By using an organic solvent and / or a polymerizable compound as the liquid medium, a non-aqueous oil-based pigment dispersion can be obtained.

[0046] For example, organic solvents that have been conventionally used in oil-based inks can be used. Examples of organic solvents include ketone solvents, hydrocarbon solvents, ester solvents, ether solvents, glycol ether solvents, and alcohol solvents, and one of these can be used alone or in combination of two or more.

[0047] Examples of ketone solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methylcyclohexanone, and diacetone alcohol. Examples of hydrocarbon solvents include aromatic hydrocarbon solvents such as toluene and xylene; aliphatic hydrocarbon solvents such as n-hexane, n-heptane, and n-octane; and alicyclic hydrocarbon solvents such as cyclopentane, cyclohexane, methylcyclohexane, dimethylcyclohexane, and cyclooctane. Examples of ester solvents include methyl acetate, ethyl acetate, n-propyl acetate, n-butyl acetate, and isobutyl acetate. Examples of ether solvents include tetrahydrofuran, dioxane, diethyl ether, and methyl ethyl ether. Examples of glycol ether solvents include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, and propylene glycol monomethyl ether. Examples of alcohol-based solvents include monohydric alcohols such as methanol, ethanol, n-propanol, isopropanol, and n-butanol; and polyhydric alcohols such as ethylene glycol, propylene glycol, and glycerin.

[0048] Polymerizable compounds can include, for example, those conventionally used in active energy ray-curable inks. Examples of polymerizable compounds include monofunctional monomers, polyfunctional monomers, photocurable oligomers, and photocurable polymers, and one of these can be used alone or in combination of two or more. In this specification, the term "(meth)acrylic" includes both the terms "acrylic" and "methacrylic." Similarly, the term "(meth)acrylate" includes both the terms "acrylate" and "methacrylate."

[0049] Examples of monofunctional monomers include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, trimethylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isobornyl (meth)acrylate, dicyclopentenyl (meth)acrylate, adamantyl (meth)acrylate, adamantylmethyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate. Examples include phosphates, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, glycidyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, polyethylene glycol mono (meth)acrylate, polyethylene glycol monomethyl ether (meth)acrylate, 2-ethoxyethyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, allyl (meth)acrylate, vinyloxyethoxyethyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, adducts of phthalic anhydride and 2-hydroxyethyl (meth)acrylate, acryloylmorpholine, and N-vinylcaprolactam.

[0050] Examples of polyfunctional monomers and photocurable oligomers include neopentyl glycol di(meth)acrylate, ethylene glycol di(meth)acrylate, poly(n=2 or more)ethylene glycol di(meth)acrylate, polypropylene glycol (n=2 or more) di(meth)acrylate, polybutylene glycol (n=2 or more) di(meth)acrylate, 2,2-bis(4-(meth)acryloxyethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxydiethoxyphenyl)propane, trimethylolpropane diacrylate, and bis(2-(meth)acryloxyethyl )-hydroxyethyl-isocyanurate, trimethylolpropane tri(meth)acrylate, tris(2-(meth)acryloxyethyl)isocyanurate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, epoxy poly(meth)acrylates such as epoxy di(meth)acrylate obtained by reacting bisphenol A type diepoxy with (meth)acrylic acid, 1,Urethane tri(meth)acrylate obtained by reacting a trimer of 6-hexamethylene diisocyanate with 2-hydroxyethyl (meth)acrylate, urethane di(meth)acrylate obtained by reacting isophorone diisocyanate with 2-hydroxypropyl (meth)acrylate, urethane hexa(meth)acrylate obtained by reacting isophorone diisocyanate with pentaerythritol tri(meth)acrylate, urethane di(meth)acrylate obtained by reacting dicyclohexyl diisocyanate with 2-hydroxyethyl (meth)acrylate, dicyclo Examples include urethane poly(meth)acrylates such as urethane di(meth)acrylate obtained by reacting hexyl diisocyanate and poly(n=6~15)tetramethylene glycol with 2-hydroxyethyl (meth)acrylate; polyester (meth)acrylate obtained by reacting trimethylolethane with succinic acid and (meth)acrylic acid; and polyester poly(meth)acrylate obtained by reacting trimethylolpropane with succinic acid, ethylene glycol, and (meth)acrylic acid.

[0051] Examples of photocurable polymers include polymers in which multiple (meth)acryloyloxy groups exhibiting radical polymerization are introduced to the terminals or side chains of polymers such as poly(meth)acrylate, polyurethane, polyester, polyamide, polyimide, and polyepoxy resin. Furthermore, alkali-developable photocurable polymers having carboxyl groups, etc., can also be used.

[0052] The content of the liquid medium in the pigment dispersion is preferably 9% by mass or more and 98% by mass or less, relative to the total mass of the pigment dispersion. The above content of the liquid medium is more preferably 29% by mass or more, and even more preferably 49% by mass or more. Furthermore, the above content of the liquid medium is more preferably 94% by mass or less, and even more preferably 89% by mass or less.

[0053] (Other ingredients) In addition to Pigment Orange 43, Pigment Orange 43 derivatives, and a liquid medium, the pigment dispersion may also contain other components. Examples of other components include colorants other than Pigment Orange 43, dispersants other than Pigment Orange 43 derivatives (e.g., polyurethane resins, acrylic resins, styrene-acrylic acid copolymers, polyester polyamide resins, etc.), surfactants, light stabilizers, UV absorbers, leveling agents, and defoaming agents, and one or more of these may be used.

[0054] (Method for producing a pigment dispersion) There are no particular restrictions on the method for producing the pigment dispersion; it can be produced by mixing and dispersing pigment orange 43, a pigment orange 43 derivative, a liquid medium, and other components as needed.

[0055] From the viewpoint of improving dispersion stability, it is preferable to adsorb a dispersant containing a pigment orange 43 derivative onto the pigment orange 43. Examples of adsorption methods include performing the adsorption during the micronization of the pigment (pigment orange 43) in processes such as salt milling or dry grinding, mixing the powders together, mixing the slurries together, or performing the adsorption during a dispersion process of the pigment using a dispersant. Among these methods, it is preferable to perform the adsorption treatment of the dispersant containing the pigment orange 43 derivative onto the particle surface of the pigment (pigment orange 43) during the dispersion process.

[0056] When producing a pigment dispersion, it is preferable to mix and stir a dispersant containing a pigment orange 43 derivative, pigment orange 43, a liquid medium, and other components as needed, and then disperse the pigment orange 43 using a disperser.

[0057] Examples of dispersers include kneaders, two-roll mixers, three-roll mixers, SS5 (product name, M-Technique Co., Ltd.), Miracle KCK (product name, Asada Steel Co., Ltd.), ultrasonic dispersers, high-pressure homogenizers such as Microfluidizer (product name, Mizuho Industries Ltd.), Nanomizer (product name, Yoshida Machinery Industry Co., Ltd.), Starburst (product name, Sugino Machine Co., Ltd.), G-Smasher (product name, Rix Co., Ltd.), paint shakers, ball mills, attritors, and sand mills. For materials using bead media such as glass, zircon, and zirconia, paint shakers, ball mills, attritors, sand mills, horizontal media mill dispersers, and colloid mills can be used. For bead media, it is preferable to use bead media with a diameter of approximately 0.5 mm to 1 mm. In the dispersion of colorants for color filters, it is preferable to perform the dispersion twice, changing the bead diameter each time. In the second dispersion, using beads with a smaller diameter than those used in the first dispersion allows for finer pigment (pigment orange 43). The resulting pigment dispersion can be used as is, but it is preferable to remove any coarse particles that may be present in small quantities using a centrifuge, ultracentrifuge, or filter.

[0058] As described above, the pigment dispersion of this embodiment contains a liquid medium, pigment orange 43, and the aforementioned specific pigment orange 43 derivative, making it possible to suppress the aggregation of pigment orange 43 more easily and providing good long-term storage stability. Therefore, by using this pigment dispersion, it is possible to provide a coating agent that has good long-term storage stability and in which pigment orange 43 is less likely to aggregate. Accordingly, the pigment dispersion can be suitably used as a colorant for active energy ray curable inkjet inks, a colorant for gravure inks, or a colorant for paints. Furthermore, because the pigment dispersion of this embodiment has good weather resistance, it is suitable for outdoor applications such as sign displays and as a colorant for color filters. Next, the coating agent will be described.

[0059] <Coating agent> A coating agent according to one embodiment of the present invention (hereinafter sometimes simply referred to as "coating agent") contains the aforementioned pigment dispersion. As described above, the pigment dispersion is preferably a non-aqueous oil-based pigment dispersion; therefore, a non-aqueous oil-based coating agent is also preferred for the coating agent.

[0060] A coating agent is an agent that adheres to the surface of an article or other object and covers at least a portion of its surface. Therefore, coating agents can be applied to a variety of uses that exhibit this effect. Specifically, examples include paints, stationery, electronic materials, gravure inks, offset inks, inkjet inks, active energy ray-curable inks, color filters, toners, cosmetics, textile printing, adhesives, tacks, photoresist materials, and medical materials. Among these, the coating agent is preferably a paint, gravure ink, inkjet ink, or active energy ray-curable ink, and more preferably a gravure ink or an active energy ray-curable inkjet ink.

[0061] The content of pigment orange 43 in the coating agent is preferably 0.1% by mass or more and 20% by mass or less, more preferably 0.5% by mass or more and 15% by mass or less, and even more preferably 1% by mass or more and 10% by mass or less, based on the total mass of the coating agent.

[0062] The coating agent may contain, in addition to the aforementioned pigment dispersion, the organic solvent and polymerizable compound described in the description of the liquid medium contained in the pigment dispersion, other components described in the description of the pigment dispersion, and other additives. A coating agent can be obtained by mixing these optional components with the aforementioned pigment dispersion. Examples of other additives include binder resins, photopolymerization initiators, photopolymerization inhibitors, slip agents, and antioxidants. These may be added during the dispersion process when preparing the pigment dispersion, but it is preferable to add them during the ink formation process.

[0063] A coating agent can be applied to a substrate, which can be any type of article, and a coating film can be formed by drying and / or reaction of the coating agent. The method of applying the coating agent is not particularly limited. For example, the coating agent can be applied to the substrate by methods such as spin coating, gravure coating, inkjet printing, screen printing, bar coating, doctor blade printing, roll coating, dip printing, spray printing, flexographic printing, and reverse roll coater.

[0064] The substrate to which the coating agent is applied is not particularly limited, and examples include substrates used in the fields of optical materials, electrical materials, building materials, recording materials, display materials, and medical materials. The coating agent can be suitably used as a surface coating agent or surface treatment agent for articles in these fields. The material of the substrate is not particularly limited, and examples include metals such as stainless steel and copper, glass, ceramics, inorganic oxides, silicon, wood, paper, and plastic materials.

[0065] As described above, the following configuration can be adopted in this embodiment. [1] A pigment dispersant for CI Pigment Orange 43, A pigment dispersant which is at least one CI pigment orange 43 derivative selected from the group consisting of compounds represented by the above general formula (1), compounds represented by the above general formula (2), and their metal salts, ammonium salts, organic amine salts, and salts of organic quaternary ammonium compounds. [2] The pigment dispersant according to [1] above, wherein the CI pigment orange 43 derivative is at least one selected from the group consisting of compounds represented by the above structural formulas (1-1), (1-2), and (2-1), as well as metal salts, ammonium salts, organic amine salts, and salts of organic quaternary ammonium compounds thereof. [3] A pigment dispersion comprising a liquid medium, CI Pigment Orange 43, and a pigment dispersant, The pigment dispersant is a pigment dispersion comprising at least one CI pigment orange 43 derivative selected from the group consisting of the compound represented by the above general formula (1), the compound represented by the above general formula (2), and their metal salts, ammonium salts, organic amine salts, and organic quaternary ammonium compounds. [4] The pigment dispersion according to [3] above, wherein the CI pigment orange 43 derivative is at least one selected from the group consisting of compounds represented by the above structural formulas (1-1), (1-2), and (2-1), as well as metal salts, ammonium salts, organic amine salts, and salts of organic quaternary ammonium compounds thereof. [5] The pigment dispersion according to [3] or [4] above, wherein the content of the CI pigment orange 43 in the pigment dispersion is 1% by mass or more and 90% by mass or less based on the total mass of the pigment dispersion. [6] The pigment dispersion according to any one of [3] to [5] above, wherein the content of the CI pigment orange 43 derivative in the pigment dispersion is 0.05% by mass or more and 40% by mass or less, relative to the content of the CI pigment orange 43 in the pigment dispersion. [7] The liquid medium is a pigment dispersion according to any one of [3] to [6] above, comprising at least one selected from the group consisting of organic solvents and polymerizable compounds. [8] A pigment dispersion according to any one of the above [3] to [7], which is a colorant for active energy ray curable inkjet inks, a colorant for gravure inks, a colorant for paints, or a colorant for color filters. [9] A coating agent containing a pigment dispersion as described in any of [3] to [8] above. [Examples]

[0066] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. In the examples and comparative examples, "parts" and "%" are based on mass unless otherwise specified.

[0067] <Preparing the materials> The following pigments, dispersants, polymerizable compounds, photopolymerization initiators, photopolymerization inhibitors, and slip agents were prepared.

[0068] (Pigment) • Pigment Orange 43 (product name "PV Gast Orange GRL", manufactured by Clariant)

[0069] (Dispersant) • Solspers 37500 (product name of Lubrizol Corporation; polyester polyamide resin)

[0070] (Polymerizable compound) • 2-(2-vinyloxyethoxy)ethyl acrylate (manufactured by Nippon Shokubai Co., Ltd.; hereinafter sometimes referred to as "VEEA"). • Isobornyl acrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd.; hereinafter sometimes referred to as "IBXA"). • N-vinylcaprolactam (manufactured by ISP Japan; hereinafter sometimes referred to as "V-CAP"). • Phenoxyethyl acrylate (Sartomer brand name "SR339A"; hereinafter sometimes referred to as "PEA").

[0071] (Photopolymerization initiator) • IRGACURE 819 (a brand name for bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide manufactured by BASF) • DAROCURE TPO (a brand name for 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide manufactured by BASF)

[0072] (Photopolymerization inhibitor) • p-Methoxyphenol (manufactured by Kanto Chemical Co., Ltd.)

[0073] (Slip agent) • BYK-UV3500 (a product name manufactured by BYK Corporation; polydimethylsiloxane with polyether-modified acrylic groups)

[0074] <Manufacturing of Pigment Orange 43 Derivatives> Pigment orange 43 derivatives (1-1), (1-2), and (2-1) were prepared according to the following procedure. A matrix-assisted laser desorption / ionization mass spectrometer (MALDI-TOF MS (hereinafter simply referred to as "MALDI"; trade name "autoflex maX", manufactured by BRUKER) was used to measure molecular weight and identify the structure.

[0075] (Synthesis Example 1) Preparation of Pigment Orange 43 Derivative (1-1) 16.5 parts of Pigment Orange 43 were added to 200 parts of 98% sulfuric acid at a temperature below 30°C, followed by the addition of 1.8 parts of paraformaldehyde. The mixture was then reacted at 50°C for 30 minutes. 12.0 parts of p-toluenesulfonic acid monohydrate were added, and the mixture was reacted at 80°C for 3 hours. After cooling, the reaction mixture was precipitated in 1,000 parts of ice water, and the mixture was repeatedly filtered and washed with water. After drying, elemental analysis of sulfur revealed that an average of 1.0 sulfone group was introduced per molecule. 19.7 parts of the Pigment Orange 43 derivative represented by the above structural formula (1-1) (referred to as "Pigment Orange 43 derivative (1-1)") were obtained.

[0076] (Synthesis Example 2) Preparation of Pigment Orange 43 Derivatives (1-2) The procedure was the same as in Synthesis Example 1, except that 12.0 parts of o-cresol-4-sulfonic acid were used instead of 12.0 parts of p-toluenesulfonic acid monohydrate used in Synthesis Example 1. In this way, 19.8 parts of the pigment orange 43 derivative represented by the above structural formula (1-2), which has an average of 1.0 sulfone group introduced per molecule as determined by elemental analysis of sulfur, were obtained (this will be referred to as "pigment orange 43 derivative (1-2)"). Mass spectrometry by MALDI detected a peak with a molecular weight of 612.

[0077] (Synthesis Example 3) Preparation of Pigment Orange 43 Derivative (2-1) The procedure was the same as in Synthesis Example 1, except that 10.2 parts of 3-methyl-1-(4-sulfophenyl)-2-pyrazolin-5-one were used instead of 12.0 parts of p-toluenesulfonic acid monohydrate used in Synthesis Example 1. In this way, 24.1 parts of the pigment orange 43 derivative represented by the above structural formula (2-1), which has an average of 1.0 sulfone group introduced per molecule as determined by elemental analysis of sulfur, were obtained (this will be referred to as "pigment orange 43 derivative (2-1)"). Mass spectrometry by MALDI detected a peak with a molecular weight of 678.

[0078] <Preparation of Pigment Dispersion> (Example 1) Preparation of orange pigment dispersion (1-1) 73.0 parts of PEA were dissolved in 12.0 parts of a dispersant (Solspers 37500), 14.5 parts of Pigment Orange 43 and 0.5 parts of the Pigment Orange 43 derivative (1-1) obtained in Synthesis Example 1 were added to obtain a mixture. This mixture was shaken in a paint shaker using 1 mm diameter zirconia beads to determine the volume-average particle size (median diameter; D) of Pigment Orange 43. 50 The particles were dispersed so that their wavelength was 200 nm or less, and the orange pigment dispersion (1-1) of Example 1 was prepared.

[0079] (Example 2) Preparation of orange pigment dispersion (1-2) The orange pigment dispersion (1-2) for Example 2 was prepared in the same manner as in Example 1, except that 0.5 parts of pigment orange 43 derivative (1-2) were used instead of 0.5 parts of pigment orange 43 derivative (1-1) used in Example 1.

[0080] (Example 3) Preparation of orange pigment dispersion (2-1) The orange pigment dispersion (2-1) for Example 3 was prepared in the same manner as in Example 1, except that 0.5 parts of pigment orange 43 derivative (2-1) were used instead of 0.5 parts of pigment orange 43 derivative (1-1) used in Example 1.

[0081] ( referenceExample 4) Preparation of orange pigment dispersion (1-3) Except for changing the amount of pigment orange 43 used (14.5 parts) and the amount of pigment orange 43 derivative (1-1) used (0.5 parts) to 14.95 parts and 0.05 parts, respectively, the procedure was the same as in Example 1. reference An orange pigment dispersion (1-3) was prepared for Example 4.

[0082] ( reference Example 5) Preparation of orange pigment dispersion (1-4) Except for changing the amount of pigment orange 43 used (14.5 parts) and the amount of pigment orange 43 derivative (1-1) used (0.5 parts) to 11.0 parts and 4.0 parts, respectively, the procedure was the same as in Example 1. reference An orange pigment dispersion (1-4) was prepared for Example 5.

[0083] (Comparative Example 1) Preparation of orange pigment dispersion (3) The orange pigment dispersion (3) for Comparative Example 1 was prepared in the same manner as in Example 1, except that Direct Yellow 8 was used instead of the Pigment Orange 43 derivative (1-1) used in Example 1.

[0084] (Comparative Example 2) Preparation of orange pigment dispersion (4) The orange pigment dispersion (4) of Comparative Example 2 was prepared in the same manner as in Example 1, except that the pigment orange 43 derivative (1-1) was not added.

[0085] <Evaluation of Pigment Dispersions> (Volume-average particle size) For each prepared orange pigment dispersion, the volume-average particle size (D) of pigment orange 43 in the pigment dispersion was determined using a particle size distribution analyzer utilizing dynamic light scattering (product name "FPAR-1000", manufactured by Otsuka Electronics Co., Ltd.). 50 ) was measured.

[0086] (Storage stability) The orange pigment dispersions prepared in each example and comparative example were immediately placed in glass bottles, sealed, and stored at 60°C for two weeks. The viscosity of the orange pigment dispersions at 25°C before and after storage was measured using an E-type viscometer (product name "TV33-L", manufactured by Toki Sangyo Co., Ltd.). The percentage increase in viscosity of the orange pigment dispersion after storage compared to the viscosity before storage, i.e., the percentage increase in viscosity, was calculated. Based on these results, the storage stability of the pigment dispersions was evaluated according to the evaluation criteria below. A smaller increase in viscosity indicates better storage stability of the orange pigment dispersion. In the evaluation criteria below, "A" and "B" represent acceptable levels, and "C" represents an unacceptable level. A: The thickness is less than 5%. B: The thickness is 5% or more but less than 10%. C: The thickness is increased by 10% or more.

[0087] (Pigment aggregation) The orange pigment dispersions prepared in each example and comparative example were filtered using filter paper (Advantec, No. 5A), and any remaining foreign matter on the filter paper was visually observed. Based on the observation results, the degree of aggregation of the pigment (Pigment Orange 43) in the pigment dispersion was evaluated according to the following evaluation criteria. The less or no foreign matter is observed, the less likely the Pigment Orange 43 in the orange pigment dispersion is to aggregate. In the evaluation criteria below, "A" and "B" represent acceptable levels, and "C" represents unacceptable levels. A: No foreign objects were found. B: Some foreign matter is observed. C: Many foreign objects were found.

[0088] Example 1~ 3. Reference Example 4 and 5. The composition (in parts) and evaluation results of the orange pigment dispersions of Comparative Examples 1 and 2 are shown in Table 1 (Tables 1-1 and 1-2).

[0089] TIFF0007867458000014.tif86170

[0090] TIFF0007867458000015.tif86170

[0091] <Preparation of inkjet inks> (Examples 6-8, and Comparative Examples 3 and 4) To each of the orange pigment dispersions obtained in Examples 1-3 and Comparative Examples 1 and 2, a polymerizable compound, a photopolymerization initiator, a photopolymerization inhibitor, and a slip agent were added to achieve the compositions shown in the upper row of Table 2 below (unit: %). In this way, non-aqueous orange inks, which are active energy ray curable inkjet inks (hereinafter sometimes simply referred to as "ink"), were prepared.

[0092] <Evaluation of inkjet inks> (Storage stability) The inks prepared in each example and comparative example were placed in glass bottles immediately after preparation, sealed, and stored at 60°C for two weeks. The viscosity of the inks at 25°C before and after storage was measured using an E-type viscometer (product name "TV33-L", manufactured by Toki Sangyo Co., Ltd.), and the percentage increase in viscosity after storage compared to the viscosity before storage, i.e., the percentage increase in viscosity, was calculated. Based on these results, the storage stability of the inks was evaluated according to the evaluation criteria below. A smaller increase in viscosity indicates better storage stability of the ink. In the evaluation criteria below, "A" and "B" represent acceptable levels, and "C" represents an unacceptable level. A: The thickness is less than 5%. B: The thickness is 5% or more but less than 10%. C: The thickness is increased by 10% or more.

[0093] (Pigment aggregation) The inks prepared in each example and comparative example were filtered using filter paper (Advantec, No. 5A), and any foreign matter remaining on the filter paper was visually observed. Based on the observation results, the degree of aggregation of the pigment (pigment orange 43) in the ink was evaluated according to the evaluation criteria below. The less or no foreign matter is observed, the less likely the pigment orange 43 in the ink was to aggregate. In the evaluation criteria below, "A" and "B" represent acceptable levels, and "C" represents unacceptable levels. A: No foreign objects were found. B: Some foreign matter is observed. C: Many foreign objects were found.

[0094] The evaluation results of the inkjet inks for Examples 6-8 and Comparative Examples 3 and 4 are shown in the lower section of Table 2.

[0095] TIFF0007867458000016.tif111170

Claims

1. A pigment dispersion comprising a liquid medium, C.I. Pigment Orange 43, and a pigment dispersant, The pigment dispersant comprises at least one C.I. Pigment Orange 43 derivative selected from the group consisting of compounds represented by the following general formula (1), compounds represented by the following general formula (2), and their metal salts, ammonium salts, organic amine salts, and organic quaternary ammonium compounds. The content of the C.I. pigment orange 43 derivative in the pigment dispersion is 1% by mass or more and 10% by mass or less, relative to the content of the C.I. pigment orange 43 in the pigment dispersion. A pigment dispersion for an active energy ray-curable ink, wherein the liquid medium is at least one selected from polymerizable compounds. (R in the general formula (1) above) １ ~R ４ Each of these independently represents a hydrogen atom, an alkyl group, an alkoxy group, a hydroxyl group, or a halogen atom, and in general formulas (1) and (2), n independently represents a number between 0.5 and 3.

2. The pigment dispersion according to claim 1, wherein the C.I. Pigment Orange 43 derivative is at least one selected from the group consisting of compounds represented by the following structural formulas (1-1), (1-2), and (2-1), as well as their metal salts, ammonium salts, organic amine salts, and salts of organic quaternary ammonium compounds.

3. The pigment dispersion according to claim 1, wherein the content of C.I. pigment orange 43 in the pigment dispersion is 1% by mass or more and 90% by mass or less with respect to the total mass of the pigment dispersion.

4. The pigment dispersion according to claim 1, which is a colorant for active energy ray-curable inkjet ink.

5. An active energy ray curable ink containing a pigment dispersion according to any one of claims 1 to 4.

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