Polymeric dispersant

Abstract

To provide a polymeric dispersant and an aqueous ink jet ink composition including the polymeric dispersant.SOLUTION: A polymeric dispersant includes a copolymer comprising: a basic moiety; an alkyl group having from about 4 to about 40 carbon atoms; an aromatic group; and a steric hydrophilic group.SELECTED DRAWING: None

Description

[Technical Field]

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS Commonly assigned U.S. patent application Ser. No. 17 / 533,206, entitled "Self-Crosslinked Polymeric Dispersant," is filed concurrently and is hereby incorporated by reference in its entirety. [Background technology]

[0002] Disclosed herein are polymeric dispersants, including copolymers that include a basic moiety, an alkyl group having from about 4 to about 40 carbon atoms, an aromatic group, and a steric hydrophilic group.

[0003] Also disclosed herein is a composition comprising particles, a vehicle, an optional surfactant, and a polymeric dispersant comprising a copolymer of the following structure:

[0004] [ka] wherein w is an integer of 1 to about 400, x is an integer of 0 to about 480, y is an integer of 1 to about 160, z is an integer of 1 to about 400, L1-L4 are optional linking groups, L1 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, L2 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, L3 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, L4 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, and R1 is —(CH2) 3-39CH3, R2 is an aromatic group having 6 to about 30 carbon atoms, and in some embodiments is selected from a member of the group consisting of benzyl, naphthalenyl, anthracenyl, tetracenyl, pentacenyl, tristyrylbenzyl, and pyridinyl, and R3 is -(CH2CH2O) m (CH2CHCH3O) n R, m is about 10 to about 450, n is about 0 to about 80, R is H or CH3, R4 is a base group selected from the group consisting of amine, pyridine, imidazole, benzimidazole, histidine, guanidine, phosphazene base, ammonium base, phosphonium base, and onium base, and R1', R2', R3', and R4' are each independently selected from the group consisting of H, alkyl groups having 1 to about 5 carbon atoms, and aromatic groups having 6 to about 30 carbon atoms.

[0005]

number

[0006] Also disclosed herein is an aqueous inkjet ink comprising water, a co-solvent, an optional wax dispersion, an optional latex resin, a surfactant, a pigment, and a polymeric dispersant comprising a copolymer of the structure:

[0007] [ka] wherein w is an integer of 1 to about 400, x is an integer of 0 to about 480, y is an integer of 1 to about 160, z is an integer of 1 to about 400, L1-L4 are optional linking groups, L1 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, L2 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, L3 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, L4 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, and R1 is —(CH2) 3-39 CH3, R2 is an aromatic group selected from the group consisting of benzyl, naphthalenyl, anthracenyl, tetracenyl, pentacenyl, tristyrylbenzyl, and pyridinyl, and R3 is -(CH2CH2O) m (CH2CHCH3O) n R, m is about 10 to about 450, n is about 0 to about 80, R is H or CH3, R4 is a base group selected from the group consisting of amine, pyridine, imidazole, benzimidazole, histidine, guanidine, phosphazene base, ammonium base, phosphonium base, and onium base, and R1', R2', R3', and R4' are each independently selected from the group consisting of H, alkyl groups having 1 to about 5 carbon atoms, and aromatic groups having 6 to about 30 carbon atoms.

[0008]

number

[0009] A reliable pigment dispersion is a key factor for aqueous inkjet ink applications. Carbon black pigments are particularly difficult to disperse in aqueous media due to the pigment's high specific surface area and low surface charge. Poorly dispersed pigments can cause aqueous inks or coatings to exhibit storage instability, jet clogging, low optical density, and loss of covering power. Attempts have been made to incorporate various black pigment dispersions made with commercially available dispersants into aqueous inkjet inks. However, the resulting inks often exhibit problems such as being unstable in accelerated aging tests or having limited resistance to ink formulation variations, especially co-solvent-based inks and contents.

[0010] Currently available dispersants may be suitable for their intended purpose. However, there remains a need for improved dispersants, particularly for aqueous inkjet inks.

[0011] The appropriate components and process aspects of each of the above U.S. patents and published patent applications may be selected for the present disclosure in its embodiments. Furthermore, throughout this application, various publications, patents, and published patent applications are referenced by specific citations. The disclosures of the publications, patents, and published patent applications referenced in this application are hereby incorporated by reference into this disclosure in order to more fully describe the state of the art to which this invention pertains. Summary of the Invention

[0012] Described are polymeric dispersants, including copolymers that include a basic moiety, an alkyl group having from about 4 to about 40 carbon atoms, an aromatic group, and a steric hydrophilic group.

[0013] Further described is a composition comprising particles, a vehicle, an optional surfactant, and a polymeric dispersant comprising a copolymer of the structure:

[0014] [ka] wherein w is an integer of 1 to about 400, x is an integer of 0 to about 480, y is an integer of 1 to about 160, z is an integer of 1 to about 400, L1-L4 are optional linking groups, L1 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, L2 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, L3 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, L4 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, and R1 is —(CH2) 3-39 CH3, R2 is an aromatic group selected from the group consisting of benzyl, naphthalenyl, anthracenyl, tetracenyl, pentacenyl, tristyrylbenzyl, and pyridinyl, and R3 is -(CH2CH2O) m (CH2CHCH3O) nR, m is about 10 to about 450, n is about 0 to about 80, R is H or CH3, R4 is a base group selected from the group consisting of amine, pyridine, imidazole, benzimidazole, histidine, guanidine, phosphazene base, ammonium base, phosphonium base, and onium base, and R1', R2', R3', and R4' are each independently selected from the group consisting of H, alkyl groups having 1 to about 5 carbon atoms, and aromatic groups having 6 to about 30 carbon atoms.

[0015] Further described is an aqueous inkjet ink comprising water, a co-solvent, an optional wax dispersion, an optional latex resin, a surfactant, a pigment, and a polymeric dispersant comprising a copolymer of the structure:

[0016] [ka] wherein w is an integer of 1 to about 400, x is an integer of 0 to about 480, y is an integer of 1 to about 160, z is an integer of 1 to about 400, L1-L4 are optional linking groups, L1 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, L2 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, L3 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, L4 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, and R1 is —(CH2) 3-39 CH3, R2 is an aromatic group selected from the group consisting of benzyl, naphthalenyl, anthracenyl, tetracenyl, pentacenyl, tristyrylbenzyl, and pyridinyl, and R3 is -(CH2CH2O) m(CH2CHCH3O) n R, m is about 10 to about 450, n is about 0 to about 80, R is H or CH3, R4 is a base group selected from the group consisting of amine, pyridine, imidazole, benzimidazole, histidine, guanidine, phosphazene base, ammonium base, phosphonium base, and onium base, and R1', R2', R3', and R4' are each independently selected from the group consisting of H, alkyl groups having 1 to about 5 carbon atoms, and aromatic groups having 6 to about 30 carbon atoms. DETAILED DESCRIPTION OF THE INVENTION

[0017] Described herein are polymeric dispersants suitable for dispersing various pigments, including carbon black, for aqueous and water-based ink applications. The dispersant polymers contain a basic moiety, an alkyl group, and a steric hydrophilic group. The basic group and alkyl group function as pigment-affine anchors. The basic moiety may include, but is not limited to, aromatic amines, aliphatic amines, pyridines, and combinations thereof. The basic moiety may be incorporated into the polymeric dispersant backbone or may be a pendant group attached to the dispersant backbone. The steric group may include polyethylene glycol having a weight-average molecular weight of about 500 to about 20,000, or about 500 to about 5,000, which provides compatibility with the dispersion medium. The polymeric dispersants can be synthesized by a manufacturable solution polymerization process. Because the dispersants are compatible with a wide variety of film-forming polymer resins and latexes by design, pigment dispersions prepared using the dispersants enable aqueous inks or coatings to have excellent storage stability, reliable jetting quality, and enhanced color strength. More specifically, black inks prepared with carbon black dispersions prepared with this dispersant exhibited excellent aging stability in various ink formulations containing different cosolvents, high cosolvent loadings, and various surfactants. Higher optical density of printed images was also demonstrated in images printed with inks containing pigment dispersions made with commercial dispersants. This dispersant falls within the category of environmentally friendly non-APE (alkyl phenol ethoxylate) dispersants.

[0018] In some embodiments, the polymeric dispersant is described as including a copolymer that includes a basic moiety, an alkyl group having from about 4 to about 40 carbon atoms, an aromatic group, and a steric hydrophilic group.

[0019] The polymeric dispersant contains a basic moiety. In some embodiments, the basic moiety is selected from the group consisting of aromatic amines, aliphatic amines, pyridine, imidazole, benzimidazole, histidine, guanidine, phosphazene bases, ammonium bases, phosphonium bases, onium bases, and combinations thereof. In some embodiments, the basic moiety is selected from the group consisting of aromatic amines, aliphatic amines, pyridine, and combinations thereof.

[0020] In some embodiments, the copolymer polymer dispersant comprises a backbone and the basic moieties are incorporated within the backbone or the basic moieties are pendant groups linked to the backbone.

[0021] The polymeric dispersant contains an alkyl group, in some embodiments, an alkyl group having from about 4 to about 40 carbon atoms.

[0022] The polymeric dispersant contains a steric hydrophilic group. In some embodiments, the steric hydrophilic group comprises a member selected from the group consisting of polyethylene glycol, polypropylene glycol, and combinations thereof. In some embodiments, the steric hydrophilic group comprises polyethylene glycol. In specific embodiments, the steric hydrophilic group comprises polyethylene glycol having a weight average molecular weight of about 500 to about 20,000, or about 500 to about 5,000.

[0023] The molecular weight of the polymeric dispersant is determined by gel permeation chromatography (GPC) according to conventional methods. The weight average molecular weight can be determined by GPC using polystyrene standards.

[0024] In some embodiments, the polymeric dispersant is a copolymer of the following structure:

[0025] [ka] wherein w is an integer from 1 to about 400, x is an integer from 0 to about 480, y is an integer from 1 to about 160, z is an integer from 1 to about 400, L1 through L4 are optional linking groups, if present, L1 through L4 are as follows: 1 is a linking group selected from the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, and L2 is an ether, urea, epoxy, ester, amide , oxygen, sulfur, and alkyl chains of 1 to about 6 carbon atoms; L3 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and alkyl chains of 1 to about 6 carbon atoms; L4 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and alkyl chains of 1 to about 6 carbon atoms; and R1 is —(CH2) 3-39 CH3, R2 is an aromatic group selected from the group consisting of benzyl, naphthalenyl, anthracenyl, tetracenyl, pentacenyl, tristyrylbenzyl, and pyridinyl, and R3 is -(CH2CH2O) m (CH2CHCH3O) n R, m is about 10 to about 450, n is about 0 to about 80, R is H or CH3, R4 is a base group selected from the group consisting of amine, pyridine, imidazole, benzimidazole, histidine, guanidine, phosphazene base, ammonium base, phosphonium base, and onium base, and R1', R2', R3', and R4' are each independently selected from the group consisting of H, alkyl groups having 1 to about 5 carbon atoms, and aromatic groups having 6 to about 30 carbon atoms.

[0026]

number

[0027] In some embodiments, the polymeric dispersant is free of alkylphenol ethoxylates, i.e., does not contain alkylphenol ethoxylates.

[0028] The polymer dispersions herein can be used for any suitable or desired composition. In some embodiments, provided herein are compositions comprising particles, a vehicle, an optional surfactant, and a polymeric dispersant comprising a copolymer of the following structure:

[0029] [ka] wherein w is an integer of 1 to about 400, x is an integer of 0 to about 480, y is an integer of 1 to about 160, z is an integer of 1 to about 400, L1-L4 are optional linking groups, L1 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, L2 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, L3 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, L4 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, and R1 is —(CH2) 3-39 CH3, R2 is an aromatic group selected from the group consisting of benzyl, naphthalenyl, anthracenyl, tetracenyl, pentacenyl, tristyrylbenzyl, and pyridinyl, and R3 is -(CH2CH2O) m (CH2CHCH3O) n R, m is about 10 to about 450, n is about 0 to about 80, R is H or CH3, R4 is a base group selected from the group consisting of amine, pyridine, imidazole, benzimidazole, histidine, guanidine, phosphazene base, ammonium base, phosphonium base, and onium base, and R1', R2', R3', and R4' are each independently selected from the group consisting of H, alkyl groups having 1 to about 5 carbon atoms, and aromatic groups having 6 to about 30 carbon atoms.

[0030]

number

[0031] The polymeric dispersants herein can be used to disperse any suitable or desired particles, including, but not limited to, pigments. In some embodiments, a composition is provided comprising particles, a vehicle, an optional surfactant, and a polymeric dispersant as described herein, wherein the particles are pigments. In further embodiments, the particles are pigments selected from the group consisting of black pigments, white pigments, cyan pigments, magenta pigments, yellow pigments, and combinations thereof. In certain embodiments, the particles are carbon black pigments.

[0032] The composition can include any suitable or desired vehicle. In some embodiments, the vehicle is water. In further embodiments, the vehicle includes water and a co-solvent. In certain embodiments, the vehicle includes water and a co-solvent, and the co-solvent is present in an amount greater than about 30 weight percent, based on the total weight of the composition, such as an ink composition.

[0033] The composition may further comprise a surfactant, hi some embodiments, the surfactant is selected from the group consisting of siloxane polyethers, ethoxylated acetylenic diols, alcohol ethoxylates, and combinations thereof.

[0034] In some embodiments, an aqueous inkjet ink is described, comprising water, a co-solvent, an optional wax dispersion, an optional latex resin, a surfactant, a pigment, and a polymeric dispersant as described herein, in some embodiments, the polymeric dispersant comprises a copolymer of the following structure:

[0035] [ka] wherein w is an integer of 1 to about 400, x is an integer of 0 to about 480, y is an integer of 1 to about 160, z is an integer of 1 to about 400, L1-L4 are optional linking groups, L1 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, L2 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, L3 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, L4 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms, and R1 is —(CH2) 3-39 CH3, R2 is an aromatic group selected from the group consisting of benzyl, naphthalenyl, anthracenyl, tetracenyl, pentacenyl, tristyrylbenzyl, and pyridinyl, and R3 is -(CH2CH2O) m (CH2CHCH3O) n R, m is about 10 to about 450, n is about 0 to about 80, R is H or CH3, R4 is a base group selected from the group consisting of amine, pyridine, imidazole, benzimidazole, histidine, guanidine, phosphazene base, ammonium base, phosphonium base, and onium base, and R1', R2', R3', and R4' are each independently selected from the group consisting of H, alkyl groups having 1 to about 5 carbon atoms, and aromatic groups having 6 to about 30 carbon atoms.

[0036]

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[0037] The ink compositions herein may consist solely of water, or may contain water and a co-solvent, humectant, or the like (hereinafter, co-solvent), such as an aliphatic alcohol, an aromatic alcohol, a diol, a glycol ether, a polyglycol ether, a primary aliphatic alcohol, a secondary aliphatic alcohol, a 1,2-alcohol, a 1,3-alcohol, a 1,5-alcohol, an ethylene glycol alkyl ether, a propylene glycol alkyl ether, a methoxylated glycerol, an ethoxylated glycerol, or a higher homolog of a polyethylene glycol alkyl ether, and specific examples thereof include, for example, ethylene glycol, propylene glycol, diethylene glycol, glycerin, dipropylene glycol, polyethylene glycol, polypropylene glycol, trimethylolpropane, 1,5-pentanediol, 2-methyl-1,3-propanediol, 2-ethyl-2-hydroxymethyl-1,3-propanediol, 3-methoxybutanol, and 3-methyl-1,5-pentanediol. and mixtures with water-soluble or water-miscible components, referred to as alcohols and alcohol derivatives, including ethanol, 1,3-propanediol, 1,4-butanediol, 2,4-heptanediol, and the like; and amides, ethers, ureas, substituted ureas, such as thiourea, ethyleneurea, alkylureas, alkylthioureas, dialkylureas, and dialkylthioureas; carboxylic acids and their salts, such as 2-methylpentanoic acid, 2-ethyl-3-propylacrylic acid, 2-ethyl-hexanoic acid, 3-ethoxypropionic acid, etc., esters, organic sulfides, organic sulfoxides, sulfones (sulfolane, etc.), carbitol, butyl carbitol, cellusolve, ethers, tripropylene glycol monomethyl ether, ether derivatives, hydroxy ethers, amino alcohols, ketones, N-methylpyrrolidone, 2-pyrrolidinone, cyclohexylpyrrolidone, amides, sulfoxides, lactones, polyelectrolytes, methylsulfonylethanol, imidazole, 1,Also suitable are 3-dimethyl-2-imidazolidinone, betaine, sugars such as 1-deoxy-D-galactitol, mannitol, inositol, substituted and unsubstituted formamides, substituted and unsubstituted acetamides, and other water-soluble or water-miscible substances, and mixtures thereof. In some embodiments, the cosolvent is selected from the group consisting of ethylene glycol, N-methylpyrrolidone, methoxylated glycerol, ethoxylated glycerol, and mixtures thereof.

[0038] When a mixture of water and a water-soluble or water-miscible organic solvent liquid is selected as the liquid vehicle, the water-to-organic cosolvent ratio can be any suitable or desired ratio, and in some embodiments, is from about 100:0 to about 30:70, or from about 97:3 to about 40:60, or from about 95:5 to about 60:40. The non-water component of the liquid vehicle generally functions as a humectant or cosolvent, having a boiling point higher than that of water (100°C). The cosolvent selected is one that mixes with water without phase separation; therefore, a cosolvent with a polarity compatible with water is selected. The organic component of the ink vehicle can also function to modify the surface tension of the ink, modify the viscosity of the ink, dissolve or disperse colorants, and / or affect the drying characteristics of the ink. In some embodiments, the ink is more attracted to paper substrates than plastic media, such as in solvent-based inks.

[0039] Water-soluble or water-miscible organics used in ink formulations can aid in surface tension, drying, leveling, etc. In some embodiments, water comprises more than 50% of the formulation, and in some embodiments, water comprises about 60 to about 70% of the ink composition. Thus, the ink compositions herein are primarily aqueous.

[0040] In certain embodiments, the co-solvent is selected from the group consisting of sulfolane, methyl ethyl ketone, isopropanol, 2-pyrrolidinone, polyethylene glycol, and mixtures thereof.

[0041] The total amount of liquid vehicle can be provided in any suitable or desired amount, hi some embodiments, the liquid vehicle is present in the ink composition in an amount of from about 75 to about 97 weight percent, from about 80 to about 95 weight percent, or from about 85 to about 95 weight percent, based on the total weight of the ink composition.

[0042] In some embodiments, the aqueous inkjet ink comprises a pigment and a polymeric dispersant as described herein, wherein the pigment and polymeric dispersant are provided together in the form of a pigment dispersion.

[0043] In some embodiments, the aqueous inkjet ink is free of alkylphenol ethoxylates.

[0044] The aqueous inkjet ink can include any suitable or desired pigment as known in the aqueous inkjet ink art, including the pigments described herein. In some embodiments, the pigment is carbon black.

[0045] Particle size is defined by the diameter of an equivalent sphere with the same volume as the actual pigment particle. Dx represents the x% of particles in the dispersion that are smaller than the size based on the volume distribution, e.g., D10 represents the 10% of particles in the dispersion that are smaller than this size. Mv is the volume mean diameter of the pigment particles in the ink.

[0046] Particles, in some embodiments, pigments, can be provided in the form of particles or pigment dispersions. In some embodiments, the pigment dispersions have a volume-weighted mean diameter of about 20 to about 500 nanometers (nm), or about 20 to about 400 nm, or about 30 to about 300 nm. In some embodiments, the dispersions comprise particles, in some embodiments, pigments, a polymeric dispersant described herein, and an optional surfactant. Particle size (volume-weighted mean diameter) is measured at room temperature via a dynamic light scattering particle size analyzer, such as a NANOTRAC FLEX or Malvern Mastersizer. The analyzer was operated in backscattering mode at an angle of 173°. Samples were diluted with deionized water and equilibrated at 25°C for 120 seconds before measurement.

[0047] Examples of suitable pigments include black pigments, white pigments, cyan pigments, magenta pigments, and yellow pigments. Furthermore, pigments can be organic or inorganic particles. Suitable inorganic pigments include carbon black. However, other inorganic pigments, such as titanium dioxide, cobalt blue (CoO-Al2O3), chrome yellow (PbCrO4), and iron oxide, may also be suitable. Suitable organic pigments include, for example, azo pigments, such as diazo pigments and monoazo pigments, polycyclic pigments (e.g., phthalocyanine pigments, such as phthalocyanine blue and phthalocyanine green), perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, isoindolinone pigments, pyranthrone pigments, and quinophthalone pigments, insoluble dye chelates (e.g., basic dye chelates and acid dye chelates), nitro pigments, nitroso pigments, and anthanthrone pigments, such as PR168. Representative examples of phthalocyanine blues and greens include copper phthalocyanine blue, copper phthalocyanine green, and their derivatives (Pigment Blue 15, Pigment Green 7, and Pigment Green 36). Representative examples of quinacridones include Pigment Orange 48, Pigment Orange 49, Pigment Red 122, Pigment Red 192, Pigment Red 202, Pigment Red 206, Pigment Red 207, Pigment Red 209, Pigment Violet 19, and Pigment Violet 42. Representative examples of anthraquinones include Pigment Red 43, Pigment Red 194, Pigment Red 177, Pigment Red 216, and Pigment Red 226. Representative examples of perylenes include Pigment Red 123, Pigment Red 149, Pigment Red 179, Pigment Red 190, Pigment Red 189, and Pigment Red 224. Representative examples of thioindigoids include Pigment Red 86, Pigment Red 87, Pigment Red 88, Pigment Red 181, Pigment Red 198, Pigment Violet 36, and Pigment Violet 38.Representative examples of heterocyclic yellows include Pigment Yellow 1, Pigment Yellow 3, Pigment Yellow 12, Pigment Yellow 13, Pigment Yellow 14, Pigment Yellow 17, Pigment Yellow 65, Pigment Yellow 73, Pigment Yellow 74, Pigment Yellow 90, Pigment Yellow 110, Pigment Yellow 117, Pigment Yellow 120, Pigment Yellow 128, Pigment Yellow 138, Pigment Yellow 150, Pigment Yellow 151, Pigment Yellow 155, and Pigment Yellow 213. Such pigments are commercially available in powder or presscake form from numerous sources, including BASF Corporation, Engelhard Corporation, and Sun Chemical Corporation. Examples of usable black pigments include carbon pigments. The carbon pigment can be any commercially available carbon pigment that provides acceptable optical density and print properties. Suitable carbon pigments for use in the present system and method include, but are not limited to, carbon black, graphite, glassy carbon, charcoal, and combinations thereof. Such carbon pigments can be produced by a variety of known processes, such as the channel process, contact process, furnace process, acetylene process, or thermal process, and are commercially available from companies such as Cabot Corporation, Columbian Chemicals Company, Evonik, and EI DuPont de Nemours and Company.Suitable carbon black pigments include, but are not limited to, pigments manufactured by Cabot Corporation such as MONARCH 1400, MONARCH 1300, MONARCH 1100, MONARCH 1000, MONARCH 900, MONARCH 880, MONARCH 800, MONARCH 700, CAB-O-JET 200, CAB-O-JET 300, REGAL, BLACK PEARLS, ELFTEX, MOGUL, and VULCAN pigments; pigments manufactured by Columbian Corporation such as RAVEN 5000 and RAVEN 3500; and pigments manufactured by Evonik Corporation such as Color Black FW 200, FW 2, FW 2V, FW 1, FW 18, FW S160, FW S170, Special Black 6, Special Black 5, Special Black 4A, Special Black 4, PRINTEX U, PRINTEX 140U, PRINTEX V, and PRINTEX 140V. The above list of pigments includes unmodified pigment particulates, small molecule-attached pigment particulates, and polymer-dispersed pigment particulates. Other pigments, as well as mixtures thereof, may also be selected. It is desirable that the particle size of the pigment be as small as possible to enable a stable colloidal suspension of the particles in the liquid vehicle and to prevent clogging of the ink channels when the ink is used in thermal or piezoelectric inkjet printers.

[0048] Particles such as pigments can be present in the ink composition in any desired or effective amount, and in some embodiments, the pigment can be present in an amount of from about 0.05 to about 15 weight percent, or from about 0.1 to about 10 weight percent, or from about 1 to about 5 weight percent, based on the total weight of the ink composition.

[0049] The disclosed ink may also contain a surfactant. Examples of suitable surfactants include ionic surfactants, anionic surfactants, cationic surfactants, nonionic surfactants, zwitterionic surfactants, and mixtures thereof. Examples of suitable surfactants include alkyl polyethylene oxides, alkylphenyl polyethylene oxides, polyethylene oxide block copolymers, acetylene polyethylene oxides, polyethylene oxide (di)esters, polyethylene oxide amines, protonated polyethylene oxide amines, protonated polyethylene oxide amides, dimethicone copolyols, and substituted amine oxides, including primary, secondary, and tertiary amine salt compounds such as hydrochlorides, acetate salts of laurylamine, coconut amine, stearyl amine, and rosin amine; lauryl trimethyl ammonium chloride, cetyl trimethyl ammonium chloride, and the like. quaternary ammonium salt type compounds such as cetylpyridinium chloride, cetylpyridinium bromide, etc.; pyridinium salt type compounds such as cetylpyridinium chloride, cetylpyridinium bromide, etc.; nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, acetylene alcohols, acetylene glycols, etc., as well as other surfactants such as 2-heptadecenyl-hydroxyethylimidazoline, dihydroxyethylstearylamine, stearyl dimethyl betaine, and lauryl hydroxyethyl betaine; fluorosurfactants, etc., and mixtures thereof.Further examples of nonionic surfactants include polyacrylic acid, metallose, methylcellulose, ethylcellulose, propylcellulose, hydroxyethylcellulose, carboxymethylcellulose, polyoxyethylene cetyl ether, polyoxyethylene lauryl ether, polyoxyethylene octyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene oleyl ether, polyoxyethylene sorbitan monolaurate, polyoxyethylene stearyl ether, polyoxyethylene nonylphenyl ether, dialkylphenoxypoly(ethyleneoxy)ethanol, available from Rhone-Poulenc as IGEPAL CA-210™, IGEPAL CA-520™, IGEPAL CA-720™, IGEPAL CO-890™, IGEPAL CO-720™, IGEPAL CO-290™, IGEPAL CA-210™, ANTAROX 890™, and ANTAROX 897™. Other examples of suitable nonionic surfactants include block copolymers of polyethylene oxide and polypropylene oxide, including those commercially available as SYNPERONIC™ PE / F (e.g., SYNPERONIC™ PE / F 108). Other examples of suitable anionic surfactants include sulfates and sulfonates, such as sodium dodecylsulfate (SDS), sodium dodecylbenzenesulfonate, dodecylnaphthalene sulfate, dialkylbenzene alkyl sulfates and sulfonates, acids such as abunic acid available from Sigma-Aldrich, NEOGEN R™, NEOGEN SC™ available from Daiichi Kogyo Seiyaku, and combinations thereof. Other examples of suitable anionic surfactants include DOWFAX™ 2A1, an alkyldiphenyloxide disulfonate from Dow Chemical Company, and / or TAYCA POWER BN2060, a branched-chain sodium dodecylbenzenesulfonate from Tayca Corporation (Japan).Other examples of suitable cationic surfactants, usually positively charged, include alkylbenzyldimethyl ammonium chloride, dialkylbenzene alkyl ammonium chloride, lauryl trimethyl ammonium chloride, alkylbenzylmethyl ammonium chloride, alkylbenzyldimethyl ammonium bromide, benzalkonium chloride, cetyl pyridinium bromide, C12, C15, C17, trimethyl ammonium bromide, halide salts of quaternized polyoxyethyl alkylamines, dodecylbenzyl triethyl ammonium chloride, MIRAPOL (trademark) and ALKAQUAT (trademark) available from Alkaril Chemical Company, SANIZOL (trademark) (benzalkonium chloride) available from Kao Chemicals, and mixtures thereof. Mixtures of any two or more surfactants can be used.

[0050] In some embodiments, the optional surfactant is present and is selected from a member of the group consisting of siloxane polyethers, ethoxylated acetylenic diols, alcohol ethoxylates, and combinations thereof.

[0051] The optional surfactant can be present in any desired or effective amount, and in embodiments, the surfactant is present in an amount of from about 0.01 to about 5 weight percent based on the total weight of the ink composition. Note that surfactants are sometimes referred to as dispersants.

[0052] The ink composition can further include a crosslinking agent. In some embodiments, the crosslinking agent is an organic amine, a dihydroxy aromatic compound, an isocyanate, a peroxide, a metal oxide, or the like, as well as mixtures thereof. Crosslinking can further enhance the physical properties of images produced from the ink composition. In some embodiments, the crosslinking agent can be present in any desired or effective amount, such as from about 0.1 to about 20 percent by weight, or from 5 to about 15 percent by weight, based on the total weight of the ink composition.

[0053] The ink composition may further comprise additives. Optional additives that may be included in the ink composition include biocides, fungicides, pH control agents such as acids or bases, phosphates, carboxylates, sulfites, amine salts, buffers, and the like, sequestering agents such as EDTA (ethylenediaminetetraacetic acid), viscosity modifiers, leveling agents, and the like, and mixtures thereof.

[0054] In embodiments, the ink composition is a low-viscosity composition. The term "low-viscosity" is used in contrast to conventional high-viscosity inks, such as screen printing inks, which tend to have a viscosity of at least 1,000 centipoise (cps). In specific embodiments, the inks disclosed herein have a viscosity of about 100 cps or less, about 50 cps or less, or about 20 cps or less, or about 2 to about 30 cps, at a temperature of about 30°C, although the viscosity can be outside these ranges. When used in inkjet printing applications, the ink composition generally has a viscosity suitable for use in the inkjet printing process. For example, for thermal inkjet printing applications, at room temperature (i.e., about 25°C), the ink viscosity is at least about 1 centipoise, about 10 centipoise or less, about 7 centipoise or less, or about 5 centipoise or less, although the viscosity can be outside these ranges. For piezoelectric inkjet printing, the ink viscosity is at least about 2 centipoise, at least about 3 centipoise, not more than about 20 centipoise, not more than about 15 centipoise, or not more than about 10 centipoise, although at jetting temperatures the viscosity can be outside of these ranges. Although jetting temperatures can be outside of these ranges, jetting temperatures can be as low as about 20-25°C, and as high as about 70°C, as high as about 50°C, or as high as about 40°C.

[0055] In certain embodiments, the ink compositions herein have a viscosity of from about 2 to about 20 centipoise at a temperature of about 30°C.

[0056] The ink composition can be prepared by any suitable process by simply mixing the components. In one process, obtaining the ink requires mixing all of the ink components together and filtering the mixture. The ink can be prepared by mixing the components, heating if desired, filtering, and then adding any desired additional additives to the mixture and mixing with gentle shaking at room temperature until a homogeneous mixture is obtained, in some embodiments, for about 5 to about 10 minutes. Alternatively, optional ink additives can be mixed with the other ink components during the ink preparation process, which can be carried out by any desired procedure (e.g., mixing all of the components, heating if desired, filtering).

[0057] Also disclosed herein is a process that includes applying an ink composition as disclosed herein to a substrate in an imaging pattern. Also disclosed herein is a process that includes applying an ink composition as disclosed herein to a substrate as an overcoat, where the overcoat can be clear, pigmented, or a combination thereof.

[0058] The ink composition can be used in a process that involves incorporating the ink composition into an inkjet printing device and ejecting droplets of the ink onto a substrate in an imaged pattern. In a specific embodiment, the printing device uses a thermal inkjet process, where ink in the nozzles is selectively heated in an imaged pattern, thereby ejecting droplets of the ink in the imaged pattern. In another embodiment, the printing device uses an acoustic inkjet process, where droplets of the ink are ejected in the imaged pattern by an acoustic beam. In yet another embodiment, the printing device uses a piezoelectric inkjet process, where droplets of the ink are ejected in the imaged pattern by vibration of a piezoelectric vibrating element. Any suitable substrate can be used.

[0059] In a specific embodiment, the process herein includes incorporating an ink prepared as disclosed herein into an inkjet printing apparatus, ejecting ink droplets in an imaged pattern onto an intermediate transfer member, heating the image to partially or completely remove the solvent, and transferring the ink in an imaged pattern from the intermediate transfer member to a final recording substrate. In a specific embodiment, the intermediate transfer member is heated to a temperature above the temperature of the final recording sheet and below the temperature of the ink in the printing apparatus. Offset or indirect printing processes are also disclosed, for example, in U.S. Pat. No. 5,389,958, the disclosure of which is incorporated herein by reference in its entirety. In a specific embodiment, the printing apparatus uses a piezoelectric printing process, in which ink droplets are ejected in an imaged pattern by vibration of a piezoelectric vibrating element.

[0060] Any suitable substrate or recording sheet can be used as the final recording sheet, including plain paper such as XEROX® 4024 paper, XEROX® Image Series paper, Courtland 4024DP paper, lined notebook paper, bond paper, silica-coated paper such as Sharp Company silica-coated paper, JuJo paper, HAMMERMILL LASERPRINT® paper, transparency materials, fabrics, textiles, plastics, polymeric films, metals, and inorganic substrates such as wood. In some embodiments, the substrate comprises a three-dimensional substrate. In some embodiments, the substrate comprises a catheter, a thermometer, a cardiac stent, a programmable pacemaker, other medical devices, a menu, food packaging materials, cosmetic tools and cosmetics, and any other desired three-dimensional substrate. In further embodiments, the substrate comprises a customizable digitally printed ID code, a short-term printable material, a three-dimensional medical substrate, and any other desired three-dimensional substrate.

[0061] In some embodiments, the aqueous inkjet ink composition provides an ink that exhibits aging stability characterized by the pigment particle size of the ink fresh as measured by NANOTRAC FLEX and the pigment particle size of the ink after aging at 60° C. for 3 days.

[0062] Fresh pigment dispersion or ink means a dispersion or ink that is freshly prepared at room temperature. Aging at 60°C for 3 days means that the pigment dispersion or ink is kept in a closed glass container at a temperature of 60°C for 3 days.

[0063] Thus, in some embodiments, the inks herein exhibit aging stability characterized by comparing the particle size of a freshly prepared ink with the particle size of the ink after aging for 3 days at 60°C, as measured by a dynamic light scattering particle size analyzer, e.g., a NANOTRAC FLEX or Malver Mastersizer. Particle size is defined by the diameter of an equivalent sphere having the same volume as the actual pigment particle. Dx represents x% of the particles in the dispersion smaller than a size based on the volume distribution, e.g., D10 represents 10% of the particles in the dispersion smaller than this size. Mv is the volume mean diameter of the pigment particles in the ink. [Example]

[0064] The following examples are presented to further define the various classes of the present disclosure. These examples are intended for illustration only and are not intended to limit the scope of the present disclosure. Also, unless otherwise stated, parts and percentages are by weight.

[0065] Example 1 Synthesis of polymer dispersant. 0.8 grams of azobisisobutyronitrile was dissolved in 20 grams of isopropanol in a 500 milliliter flask preheated to 82°C under nitrogen. 8 grams of 4-vinylpyridine, 6 grams of behenyl methacrylate, 0.8 grams of azobisisobutyronitrile, and 72 grams of poly(ethylene glycol) methyl ether methacrylate (50 weight percent in water, weight average molecular weight approximately 3,600) were dissolved in a solution of 100 grams of isopropanol and 20 grams of methyl ethyl ketone. The resulting monomer solution was fed into the flask at a rate of 2 milliliters / minute. After all the monomers were fed, the monomers were held at 82°C for 4 hours. The solvent was then removed under vacuum, and water was added to adjust the solids content of the dispersant solution to 25 weight percent.

[0066] Example 2 Preparation of pigment dispersion: 20 parts pigment (Raven 1180P manufactured by Birla Carbon), 20 parts dispersant solution (20 weight percent) of Example 1, 6 parts 1,2-hexanediol, and 54 parts water were homogenized. The resulting dispersion was mixed with 400 parts zirconia beads (0.3 mm) and milled using a paint shaker at 820 revolutions per minute (rpm) for 3 hours to obtain a pigment dispersion.

[0067] Example 3 Ink preparation: 51 parts of the pigment dispersion of Example 2 (11.33 weight percent pigment), 25 parts of 1,2-propanediol, 5 parts of 1,2-hexanediol, 9 parts (44 weight percent solids) of latex resin (JONCRYL® 541 available from BASF), 1 part of surfactant (BYK-3451), 0.1 part of Proxel® (isothiazolinone, 1,2-benzisothiazolin-3-one, preservative), 1 part of wax dispersion (0.35 weight percent solids) (Joncryl® Wax-35), and 6 parts of water were mixed and filtered through a 1-micrometer glass membrane filter to remove any coarse particles. The resulting ink was subjected to various ink property evaluations and initial Dimatix printing tests.

[0068] Example 4 Ink preparation: 51 parts (11.33 weight percent pigment) of the pigment dispersion of Example 2, 25 parts 1,2-propanediol, 7 parts 1,2-hexanediol, 4 parts (44 weight percent solids) of latex resin (JONCRYL® 541 available from BASF), 1 part surfactant (BYK-3451), 0.1 parts Proxel®, 1 part wax dispersion (0.35 weight percent solids) (Joncryl® Wax-35), and 6 parts water were mixed and filtered through a 1-micrometer glass membrane filter to remove any coarse particles. The resulting ink was subjected to various ink property evaluations and initial Dimatix printing tests.

[0069] Example 5 Ink preparation: 51 parts (11.33 weight percent pigment) of the pigment dispersion of Example 2, 27 parts 1,2-propanediol, 9 parts 1,2-hexanediol, 9 parts (44 weight percent solids) of latex resin (JONCRYL® 541 available from BASF), 1 part surfactant (BYK-3451), 0.1 parts Proxel®, 1 part wax dispersion (0.35 weight percent solids) (Joncryl® Wax-35), and 6 parts water were mixed and filtered through a 1-micrometer glass membrane filter to remove any coarse particles. The resulting ink was subjected to various ink property evaluations and initial Dimatix printing tests.

[0070] Comparative Example 6 Preparation of ink using a commercially available block copolymer dispersant. 51 parts (11.33 weight percent pigment) of the pigment dispersion prepared in Example 2, excluding DISPEX® Ultra PX 4575 (an acrylic block copolymer formulation in water available from BASF), 28.5 parts 1,2-propanediol, 2.5 parts 1,2-hexanediol, 9 parts (44 weight percent solids) of latex resin (JONCRYL® 541 available from BASF), 1 part surfactant (BYK-3451), 0.1 part Proxel®, 1 part wax dispersion (0.35 weight percent solids) (Joncryl® Wax-35), and 6 parts water were mixed and filtered through a 1-micrometer glass membrane filter to remove any coarse particles. The resulting ink was subjected to various ink characterizations and initial Dimatix printing tests.

[0071] Characterization results.

[0072] Ink Stability. Accelerated storage stability was determined by placing the ink in a 60°C oven and then measuring the particle size after a specified aging time using a Nanotrac particle size analyzer. "Nanotrac" is the model name for a particle size analyzer made by Microtrac, which uses dynamic light scattering technology. Table 1 shows the characterization results for black inks prepared with the carbon black dispersions of Examples 3, 4, and 5.

[0073] [Table 1]

[0074] The particle size of the black ink of Comparative Example 6 is shown in Table 2.

[0075] [Table 2]

[0076] Thus, dispersants have been described that have or provide advantageous properties, including that they are highly effective non-APE dispersants for dispersing a variety of pigments, that inks prepared using the dispersants exhibit excellent stability and print performance, and that the dispersants are cost-effective and manufacturable in their synthesis.

[0077] It will be understood that various of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also, various presently unforeseen or unprecedented substitutions, modifications, variations, or improvements may occur to those skilled in the art, which are also intended to be encompassed by the following claims. Unless specifically recited in a claim, no particular order, number, position, size, shape, angle, color, or material of the steps or components of the claims should be implied or implied from this specification or any other claim.

Claims

1. 1. A polymeric dispersant comprising: A copolymer comprising: a basic moiety; and an alkyl group having from about 4 to about 40 carbon atoms; an aromatic group; and a steric hydrophilic group.

2. 2. The polymeric dispersant of claim 1, wherein the basic moiety is selected from a member of the group consisting of aromatic amines, aliphatic amines, pyridine, imidazole, benzimidazole, histidine, guanidine, phosphazene bases, ammonium bases, phosphonium bases, onium bases, and combinations thereof.

3. 10. The polymeric dispersant of claim 1, wherein the copolymer comprises a backbone and the basic moieties are incorporated within the backbone or are pendant groups attached to the backbone.

4. 10. The polymeric dispersant of claim 1, wherein the steric hydrophilic group comprises a member selected from the group consisting of polyethylene glycol, polypropylene glycol, and combinations thereof.

5. 10. The polymeric dispersant of claim 1, wherein the steric hydrophilic group comprises polyethylene glycol having a weight average molecular weight of from about 500 to about 20,000.

6. The copolymer has the following structure: 【Chemistry 1】 wherein w is an integer from 1 to about 400; x is an integer from 0 to about 480; y is an integer from 1 to about 160; z is an integer from 1 to about 400; L 1 ~L 4 is an optional linking group, L 1 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms; L 2 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms; L 3 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms; L 4 is a linking group selected from a member of the group consisting of ether, urea, epoxy, ester, amide, oxygen, sulfur, and an alkyl chain of 1 to about 6 carbon atoms; R 1 But -(CH 2 ) 3-39 CH 3 and R 2 is an aromatic group selected from the group consisting of benzyl, naphthalenyl, anthracenyl, tetracenyl, pentacenyl, tristyrylbenzyl, and pyridinyl; R 3 But -(CH 2 CH 2 O) m (CH 2 CHCH 3 O) n R, m is from about 10 to about 450, n is from about 0 to about 80, and R is H or CH 3 and R 4 is a base group selected from members of the group consisting of amines, pyridines, imidazoles, benzimidazoles, histidines, guanidines, phosphazene bases, ammonium bases, phosphonium bases, and onium bases; R 1 ', R 2 ', R 3 ', and R 4 10. The polymeric dispersant of claim 1, wherein each ' is independently selected from a member of the group consisting of H, an alkyl group having 1 to about 5 carbon atoms, and an aromatic group having 6 to about 30 carbon atoms.

7. 10. The polymeric dispersant of claim 1, wherein the polymeric dispersant is free of alkylphenol ethoxylates.

8. formula [Equation 1] is used to define the dispersant component, wherein w, x, y, and z are integers, w is an integer from 1 to about 400, x is an integer from 0 to about 480, y is an integer from 1 to about 160, and z is an integer from 1 to about 400; M R1 But, R 1 is the molecular weight of the group, M R1 ', R 1 is the molecular weight of the ' group, and M R2 But, R 2 is the molecular weight of the group, M R2 ', R 2 is the molecular weight of the ' group, and M R3 But, R 3 is the molecular weight of the group, M R3 ', R 3 is the molecular weight of the ' group, and M R4 But, R 4 is the molecular weight of the group, and M R4 ', R 4 7. The polymeric dispersant of claim 6, wherein the molecular weight of the ' group is

Images