Patent Grant
11169461
The present disclosure relates, in various embodiments, to toners for use in an electrostatographic machine.
The European Commission has adopted the 14th adaptation to technical progress (ATP) of the CLP Regulation. It includes the classification of inhalable powder forms of titanium dioxide (TiO2) as a category 2 carcinogen. The new requirement for titanium dioxide products to carry cancer warnings on the label applies to mixtures in powder forms containing 1% or more of the substance with aerodynamic diameter of 10 μm or less.
A non-carcinogenic alternative to TiO2 in toner formulations that provides equivalent performance is desired.
According to various embodiments, there is provided a toner composition. The toner composition includes toner particles including a resin, a colorant, and a surface additive applied to a surface of the toner particles. The surface additive includes strontium titanate (SrTiO3), silica (SiO2), silicon tetrachloride (SiCl4) and a charge control agent.
A further aspect described herein is a developer. The developer includes a toner composition including toner particles, a colorant, and a surface additive applied to a surface of the toner particles. The surface additive includes strontium titanate (SrTiO3), silica (SiO2), silicon tetrachloride (SiCl4) and a charge control agent. The developer includes a toner carrier.
A further aspect described herein is a toner composition. The toner composition includes toner particles including a resin, and a surface additive applied to a surface of the toner particles. The surface additive includes strontium titanate (SrTiO3), silica (SiO2), silicon tetrachloride (SiCl4) and a charge control agent.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several embodiments of the present teachings and together with the description, serve to explain the principles of the present teachings.
It should be noted that some details of the FIGS. have been simplified and are drawn to facilitate understanding of the embodiments rather than to maintain strict structural accuracy, detail, and/or scale.
In the following description, reference is made to the chemical formulas that form a part thereof, and in which is shown by way of illustration specific exemplary embodiments in which the present teachings may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the present teachings and it is to be understood that other embodiments may be utilized and that changes may be made without departing from the scope of the present teachings. The following description is, therefore, merely exemplary and non-limiting.
Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the disclosure are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements. Moreover, all ranges disclosed herein are to be understood to encompass any sub-ranges subsumed therein. For example, a range of “less than 10” can include any and all sub-ranges between (and including) the minimum value of zero and the maximum value of 10, that is, any and all sub-ranges having a minimum value of equal to or greater than zero and a maximum value of equal to or less than 10, e.g., 1 to 5. In certain cases, the numerical values as stated for the parameter can take on negative values. In this case, the example value of range stated as “less than 10” can assume negative values, e.g. −1, −2, −3, −10, −20, −30, etc.
Although embodiments of the disclosure herein are not limited in this regard, the terms “plurality” and “a plurality” as used herein may include, for example, “multiple” or “two or more.” The terms “plurality” or “a plurality” may be used throughout the specification to describe two or more components, devices, elements, units, parameters, or the like. For example, “a plurality of resistors” may include two or more resistors.
The toner may be any suitable or desired toner including conventional toner prepared by mechanical grinding processes or a chemical toner prepared by chemical processes such as emulsion aggregation and suspension polymerization.
The present embodiments address the problems faced by surface toner additives such as titanium dioxide (TiO2). The present embodiments provide strontium titanate (SrTiO3) mixed with silica (SiO2), which has been reacted with silicon tetrachloride (SiCl4) and a charge control agent. The nominal amount of strontium titanate (SrTiO3) mixed with silica (SiO2), which has been reacted with silicon tetrachloride (SiCl4) and a charge control agent on the toner particles is 0.2 to 1.1 pph (parts per hundred), or in embodiments 0.3 to 1.0 pph or from 0.4 pph to 1.0 pph.
Emulsion Aggregation Toner
In embodiments, the latex polymer may be composed of a first and a second monomer composition. Any suitable monomer or mixture of monomers may be selected to prepare the first monomer composition and the second monomer composition. The selection of the monomer or mixture of monomers for the first monomer composition is independent of that for the second monomer composition and vise versa. Exemplary monomers for the first and/or the second monomer compositions include, but are not limited to, polyesters; styrene; alkyl acrylate, such as, methyl acrylate, ethyl acrylate, butyl arylate, isobutyl acrylate, dodecyl acrylate, n-octyl acrylate, 2-chloroethyl acrylate, β-carboxy ethyl acrylate (β-CEA), phenyl acrylate, methyl alphachloroacrylate, methyl methacrylate, ethyl methacrylate and butyl methacrylate; butadiene; isoprene; methacrylonitrile; acrylonitrile; vinyl ethers, such as, vinyl methyl ether, vinyl isobutyl ether, vinyl ethyl ether and the like; vinyl esters, such as, vinyl acetate, vinyl propionate, vinyl benzoate and vinyl butyrate; vinyl ketones, such as, vinyl methyl ketone, vinyl hexyl ketone and methyl isopropenyl ketone; vinylidene halides, such as, vinylidene chloride and vinylidene chlorofluoride; N-vinyl indole; N-vinyl pyrrolidone; methacrylate; acrylic acid; methacrylic acid; acrylamide; methacrylamide; vinylpyridine; vinylpyrrolidone; vinyl-N-methylpyridinium chloride; vinyl naphthalene; p-chlorostyrene; vinyl chloride; vinyl bromide; vinyl fluoride; ethylene; propylene; butylenes; isobutylene; and the like, or mixtures thereof. In case a mixture of monomers is used, typically the latex polymer will be a copolymer.
In some embodiments, the first monomer composition and the second monomer composition may comprise independently of each other two or three or more different monomers. The latex polymer therefore may comprise a copolymer. Illustrative examples of such a latex copolymer includes poly(styrene-n-butyl acrylate-β-CEA), poly(styrene-alkyl acrylate), poly(styrene-1,3-diene), poly(styrene-alkyl methacrylate), poly(alkyl methacrylate-alkyl acrylate), poly(alkyl methacrylate-aryl acrylate), poly(aryl methacrylate-alkyl acrylate), poly(alkyl methacrylate), poly(styrene-alkyl acrylate-acrylonitrile), poly(styrene-1,3-diene-acrylonitrile), poly(alkyl acrylate-acrylonitrile), poly(styrene-butadiene), poly(methylstyrene-butadiene), poly(methyl methacrylate-butadiene), poly(ethyl methacrylate-butadiene), poly(propyl methacrylate-butadiene), poly(butyl methacrylate-butadiene), poly(methyl acrylate-butadiene), poly(ethyl acrylate-butadiene), poly(propyl acrylate-butadiene), poly(butyl acrylate-butadiene), poly(styrene-isoprene), poly(methylstyrene-isoprene), poly(methyl methacrylate-isoprene), poly(ethyl methacrylate-isoprene), poly(propyl methacrylate-isoprene), poly(butyl methacrylate-isoprene), poly(methyl acrylate-isoprene), poly(ethyl acrylate-isoprene), poly(propyl acrylate-isoprene), poly(butyl acrylate-isoprene); poly(styrene-propyl acrylate), poly(styrene-butyl acrylate), poly(styrene-butadiene-acrylonitrile) or polystyrene-butyl acrylate-acrylonitrile), and the like.
In embodiments, the first monomer composition and the second monomer composition may be substantially water insoluble, such as, hydrophobic, and may be dispersed in an aqueous phase with adequate stirring when added to a reaction vessel.
The weight ratio between the first monomer composition and the second monomer composition may be in the range of from about 0.1:99.9 to about 50:50, including from about 0.5:99.5 to about 25:75, from about 1:99 to about 10:90.
In embodiments, the first monomer composition and the second monomer composition may be the same. Examples of the first and the second monomer compositions may be a mixture comprising styrene and alkyl acrylate, such as, a mixture comprising styrene, n-butyl acrylate and β-CEA. Based on total weight of the monomers, styrene may be present in an amount from about 1% to about 99%, from about 50% to about 95%, from about 70% to about 90%, although may be present in greater or lesser amounts; alkyl acrylate, such as, n-butyl acrylate, may be present in an amount from about 1% to about 99%, from about 5% to about 50%, from about 10% to about 30%, although may be present in greater or lesser amounts.
In embodiments, the resins may be a polyester resin, such as, an amorphous resin, a crystalline resin, and/or a combination thereof, including the resins described in U.S. Pat. Nos. 6,593,049 and 6,756,176, the disclosure of each of which is hereby incorporated by reference in entirety. Suitable resins may also include a mixture of an amorphous polyester resin and a crystalline polyester resin as described in U.S. Pat. No. 6,830,860, the disclosure of which is hereby incorporated by reference in entirety.
In embodiments, the resin may be a polyester resin formed by reacting a diol with a diacid in the presence of an optional catalyst. For forming a crystalline polyester, suitable organic diols include aliphatic diols with from about 2 to about 36 carbon atoms, such as 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol or the like; alkali sulfo-aliphatic diols such as sodio 2-sulfo-1,2-ethanediol, lithio 2-sulfo-1,2-ethanediol, potassio 2-sulfo-1,2-ethanediol, sodio 2-sulfo-1,3-propanediol, lithio 2-sulfo-1,3-propanediol, potassio 2-sulfo-1,3-propanediol, or any mixtures thereof, and the like. The aliphatic diol may be, for example, selected in an amount of from about 40 to about 60 mole percent, in embodiments from about 42 to about 55 mole percent, in embodiments from about 45 to about 53 mole percent (although amounts outside of these ranges may also be used) of the resin, and the alkali sulfo-aliphatic diol may be selected in an amount of from about 0 to about 10 mole percent, in embodiments from about 1 to about 4 mole percent of the resin.
Examples of organic diacids or diesters including vinyl diacids or vinyl diesters selected for the preparation of the crystalline resins include, but are not limited to, oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, fumaric acid, dimethyl fumarate, dimethyl itaconate, cis, 1,4-diacetoxy-2-butene, diethyl fumarate, diethyl maleate, phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, cyclohexane dicarboxylic acid, malonic acid and mesaconic acid, a diester or anhydride thereof; and an alkali sulfo-organic diacid such as the sodium, lithium or potassium salt of dimethyl-5-sulfo-isophthalate, dialkyl-5-sulfo-isophthalate-4-sulfo-1,8-naphthalic anhydride, 4-sulfo-phthalic acid, dimethyl-4-sulfo-phthalate, dialkyl-4-sulfo-phthalate, 4-sulfophenyl-3,5-dicarbomethoxybenzene, 6-sulfo-2-naphthyl-3,5-dicarbomethoxybenzene, sulfo-terephthalic acid, dimethyl-sulfa-terephthalate, 5-sulfo-isophthalic acid, dialkyl-sulfo-terephthalate, sulfoethanediol, 2-sulfopropanediol, 2-sulfobutanediol, 3-sulfopentanediol, 2-sulfohexanediol, 3-sulfo-2-methylpentanediol, 2-sulfo-3,3-dimethylpentanediol, sulfo-p-hydroxybenzoic acid, N,N-bis(2-hydroxyethyl)-2-amino ethane sulfonate, or mixtures thereof. The organic diacid may be selected in an amount of, for example, in embodiments from about 40 to about 60 mole percent, in embodiments from about 42 to about 52 mole percent, in embodiments from about 45 to about 50 mole percent of the resin, and the alkali sulfa-aliphatic diacid may be selected in an amount of from about 1 to about 10 mole percent of the resin.
Examples of crystalline resins include polyesters, polyamides, polyimides, polyolefins, polyethylene, polybutylene, polyisobutyrate, ethylene-propylene copolymers, ethylene-vinyl acetate copolymers, polypropylene, any mixtures thereof, or the like. Specific crystalline resins may be polyester based, such as poly(ethylene-adipate), poly(propylene-adipate), poly(butylene-adipate), poly(pentylene-adipate), poly(hexylene-adipate), poly(octylene-adipate), poly(ethylene-succinate), poly(propylene-succinate), poly(butylene-succinate), poly(pentylene-succinate), poly(hexylene-succinate), poly(octylene-succinate), poly(ethylene-sebacate), poly(propylene-sebacate), poly(butylene-sebacate), poly(pentylene-sebacate), poly(hexylene-sebacate), poly(octylene-sebacate), poly(decylene-sebacate), poly(decylene-decanoate), poly(ethylene-decanoate), poly(ethylene dodecanoate), poly(nonylene-sebacate), poly(nonylene-decanoate), copoly(ethylene-fumarate)-copoly(ethylene-sebacate), copoly(ethylene-fumarate)-copoly(ethylene-decanoate), copoly(ethylene-fumarate)-copoly(ethylene-dodecanoate), alkali copoly(5-sulfoisophthaloyl)-copoly(ethylene-adipate), alkali copoly(5-sulfoisophthaloyl)-copoly(propylene-adipate), alkali copoly(5-sulfoisophthaloyl)-copoly(butylene-adipate), alkali copoly(5-sulfo-isophthaloyl)-copoly(pentylene-adipate), alkali copoly(5-sulfo-isophthaloyl)-copoly(hexylene-adipate), alkali copoly(5-sulfo-isophthaloyl)-copoly(octylene-adipate), alkali copoly(5-sulfo-isophthaloyl)-copoly(ethylene-adipate), alkali copoly(5-sulfo-isophthaloyl)-copoly (propylene-adipate), alkali copoly(5-sulfo-isophthaloyl)-copoly(butylene-adipate), alkali copoly(5-sulfo-isophthaloyl)-copoly(pentylene-adipate), alkali copoly(5-sulfo-isophthaloyl)-copoly(hexylene-adipate), alkali copoly(5-sulfo-isophthaloyl)-copoly(octylene-adipate), alkali copoly(5-sulfoisophthaloyl)-copoly(ethylene-succinate), alkali copoly(5-sulfoisophthaloyl)-copoly(propylene-succinate), alkali copoly(5-sulfoisophthaloyl)-copoly(butylenes-succinate), alkali copoly(5-sulfoisophthaloyl)-copoly(pentylene-succinate), alkali copoly(5-sulfoisophthaloyl)-copoly(hexylene-succinate), alkali copoly(5-sulfoisophthaloyl)-copoly(octylene-succinate), alkali copoly(5-sulfo-isophthaloyl)-copoly(ethylene-sebacate), alkali copoly(5-sulfo-isophthaloyl)-copoly(propylene-sebacate), alkali copoly(5-Sillfo-isophthaloyl)-copoly(butylene-sebacate), alkali copoly(5-sulfo-isophthaloyl)-copoly(pentylene-sebacate), alkali copoly(5-sulfo-isophthaloyl)-copoly(hexylene-sebacate), alkali copoly(5-sulfo-isophthaloyl)-copoly(octylene-sebacate), alkali copoly(5-sulfo-isophthaloyl)-copoly(ethylene-adipate), alkali copoly(5-sulfo-isophthaloyl)-copoly(propylene-adipate), alkali copoly(5-sulfo-isophthaloyl)-copoly(butylene-adipate), alkali copoly(5-sulfo-isophthaloyl)-copoly(pentylene-adipate), alkali copoly(5-sulfo-isophthaloyl)-copoly(hexylene-adipate), poly(octylene-adipate), wherein alkali is a metal such as sodium, lithium or potassium. Examples of polyamides include, but are not limited to, poly(ethylene-adipamide), poly(propylene-adipamide), poly(butylenes-adipamide), poly(pentylene-adipamide), poly(hexylene-adipamide), poly(oetylene-adipamide), poly(ethylene-succinimide), and poly(propylene-sebecamide). Examples of polyimides include poly(ethylene-adipimide), poly(propylene-adipimide), poly(butylene-adiphnide), poly(pentylene-adipimide), poly(hexylene-adipimide), poly(octylene-adipimide), poly(ethylene-succinimide), poly(propylene-succinimide), and poly(butylene-succinimide).
The crystalline resin may be present, for example, in an amount of from about 5 to about 50 percent by weight of the toner components, in embodiments from about 10 to about 35 percent by weight of the toner components. The crystalline resin may possess various melting points of, for example, from about 30° C. to about 120° C., in embodiments from about 50° C. to about 90° C. The crystalline resin may have a number average molecular weight (Ma), as measured by gel permeation chromatography (GPC) of, for example, from about 1,000 to about 50,000, in embodiments from about 2,000 to about 25,000, and a weight average molecular weight (Mw) of, for example, from about 2,000 to about 100,000, in embodiments from about 3,000 to about 80,000, as determined by Gel Permeation Chromatography using polystyrene standards. The molecular weight distribution (Mw/Mn) of the crystalline resin may be, for example, from about 2 to about 6, in embodiments from about 3 to about 4.
Examples of diacids or diesters including vinyl diacids or vinyl diesters utilized for the preparation of amorphous polyesters include, but are not limited to, dicarboxylic acids or diesters such as terephthalic acid, phthafic acid, isophthalic acid, fumaric acid, dimethyl fumarate, dimethyl itaconate, cis-1,4-diacetoxy-2-butene, diethyl fumarate, diethyl maleate, maleic acid, succinic acid, itaconic acid, succinic acid, succinic anhydride, dodecylsuccinic acid, dodecylsuccinic anhydride, glutaric acid, glutaric anhydride, adipic acid, pimelic acid, suberic acid, azelaic acid, dodecane diacid, dimethyl terephthalate, diethyl terephthalate, dimethylisophthalate, diethylisophthalate, dimethylphthalate, phthalic anhydride, diethylphthalate, dimethylsuccinate, dimethylfumarate, dimethylmaleate, dimethylglutarate, dimethyladipate, dimethyl dodecylsuccinate, or any combinations thereof. The organic diacid or diester may be present, for example, in an amount from about 40 to about 60 mole percent of the resin, in embodiments from about 42 to about 52 mole percent of the resin, in embodiments from about 45 to about 50 mole percent of the resin. Examples of the alkylene oxide adducts of bisphenol include, but are not limited to, polyoxypropylene (2.2)-2,2-bis(4-hydroxyphenyl) propane, polyoxypropylene (3.3)-2,2-bis(4-hydroxyphenyl) propane, polyoxyethylene (2.0)-2,2-bis(4-hydroxyphenyl) propane, polyoxyethylene (2.2)-2,2-bis(4-hydroxyphenyl) propane, polyoxypropylene (2.0)-polyoxyethylene (2.0)-2,2-bis(4-hydroxyphenyl) propane, and polyoxypropylene (6)-2,2-bis(4-hydroxyphenyl) propane. These compounds may be used singly or as a combination of two or more thereof.
Examples of additional diols which may be utilized in generating the amorphous polyester include, but are not limited to, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, pentanediol, hexanediol, 2,2-dimethylpropanediol, 2,2,3-trimethylhexanediol, heptanediol, dodecanediol, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, xylenedimethanol, cyclohexanediol, diethylene glycol, dipropylene glycol, dibutylene, or any combinations thereof. The amount of organic diol selected may vary, and may be present, for example, in an amount from about 40 to about 60 mole percent of the resin, in embodiments from about 42 to about 55 mole percent of the resin, in embodiments from about 45 to about 53 mole percent of the resin.
Polycondensation catalysts which may be utilized in forming either the crystalline or amorphous polyesters include, but are not limited to, tetraalkyl titanates, dialkyltin oxides such as dibutyltin oxide, tetraalkyltins such as dibutyltin dilaurate, dialkyltin oxide hydroxides such as butyltin oxide hydroxide, aluminum alkoxides, alkyl zinc, dialkyl zinc, zinc oxide, stannous oxide, or any combinations thereof. Such catalysts may be utilized in amounts of, for example, from about 0.01 mole percent to about 5 mole percent based on the starting diacid or diester used to generate the polyester resin.
In embodiments, suitable amorphous resins include polyesters, polyamides, polyimides, polyolefins, polyethylene, polybutylene, polyisobutyrate, ethylene-propylene copolymers, ethylene-vinyl acetate copolymers, polypropylene, or any combinations thereof, and the like. Examples of amorphous resins which may be utilized include, but are not limited to, alkali sulfonated-polyester resins, branched alkali sulfonated-polyester resins, alkali sulfonated-polyimide resins, or branched alkali sulfonated-polyimide resins. Alkali sulfonated polyester resins may be useful in embodiments, such as the metal or alkali salts of copoly(ethylene-terephthalate)-copoly(ethylene-5-sulfo-isophthalate), copoly(propylene-terephthalate)-copoly(propylene-5-sulfo-isophthalate), copoly(diethylene-terephthalate)-copoly(diethylene-5-sulfo-isophthalate), copoly(propylene-diethylene-terephthalate)-copoly(propylene-diethylene-5-sulfoisophthalate), copoly(propylene-butylene-terephthalate)-copoly(propylene-butylene-5-sulfoisophthalate), copoly(propoxylated bisphenol-A-fumarate)-copoly(propoxylated bisphenol A-5-sulfo-isophthalate), copoly(ethoxylated bisphenol-A-fumarate)-copoly(ethoxylated bisphenol-A-5-sulfo-isophthalate), and copoly(ethoxylated bisphenol-A-maleate)-copoly(ethoxylated bisphenol-A-5-sulfo-isophthalate), wherein the alkali metal is, for example, a sodium, lithium or potassium ion.
In embodiments, as noted above, an unsaturated amorphous polyester resin may be utilized as a latex resin. Examples of such resins include those disclosed in U.S. Pat. No. 6,063,827, the disclosure of which is hereby incorporated by reference in its entirety. Exemplary unsaturated amorphous polyester resins include, but are not limited to, poly(propoxylated bisphenol co-fumarate), poly(ethoxylated bisphenol co-fumarate), poly(butyloxylated bisphenol co-fumarate), poly(co-propoxylated bisphenol co-ethoxylated bisphenol co-fumarate), poly(1,2-propylene fumarate), poly(propoxylated bisphenol co-maleate), poly(ethoxylated bisphenol co-maleate), poly(butyloxylated bisphenol co-maleate), poly(co-propoxylated bisphenol co-ethoxylated bisphenol co-maleate), poly(1,2-propylene maleate), poly(propoxylated bisphenol co-itaconate), poly(ethoxylated bisphenol co-itaconate), poly(butyloxylated bisphenol co-itaconate), poly(co-propoxylated bisphenol co-ethoxylated bisphenol co-itaconate), poly(1,2-propylene itaconate), or any combinations thereof.
Furthermore, in embodiments, a crystalline polyester resin may be contained in the binding resin. The crystalline polyester resin may be synthesized from an acid (dicarboxylic acid) component and an alcohol (diol) component. In what follows, an “acid-derived component” indicates a constituent moiety that was originally an acid component before the synthesis of a polyester resin and an “alcohol-derived component” indicates a constituent moiety that was originally an alcoholic component before the synthesis of the polyester resin.
A “crystalline polyester resin” indicates one that shows not a stepwise endothermic amount variation but a clear endothermic peak in differential scanning calorimetry (DSC). However, a polymer obtained by copolymerizing the crystalline polyester main chain and at least one other component may also be called a crystalline polyester if the amount of the other component is 50% by weight or less.
As the acid-derived component, an aliphatic dicarboxylic acid may be utilized, such as a straight chain carboxylic acid. Examples of straight chain carboxylic acids include, but are not limited to, oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,9-nonanedicarboxylic acid, 1,10-decanedicarboxylic acid, 1,1-undecanedicarboxylic acid, 1,12-dodecanedicarboxylic acid, 1,13-tridecanedicarboxylic acid, 1,14-tetradecanedicarboxylic acid, 1,16-hexadecanedicarboxylic acid, or 1,18-octadecanedicarboxylic acid, as well as lower alkyl esters and acid anhydrides thereof. Among these, acids having 6 to 10 carbon atoms may be desirable for obtaining suitable crystal melting point and charging properties. In order to improve the crystallinity, the straight chain carboxylic acid may be present in an amount of about 95% by mole or more of the acid component and, in embodiments, more than about 98% by mole percent of the acid component. Other acids are not particularly restricted, and examples thereof include conventionally known divalent carboxylic acids and dihydric alcohols. Specific examples of the monomer components include, as divalent carboxylic acids, dibasic acids such as phthalic acid, isophthalic acid, terephthalic acid, naphthalene-2,6-dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, or cyclohexanedicarboxylic acid, or anhydrides and lower alkyl esters thereof, as well as any combinations thereof, and the like. As the acid-derived component, a component such as a dicarboxylic acid-derived component having a sulfonic acid group may also be utilized. The dicarboxylic acid having a sulfonic acid group may be effective for obtaining excellent dispersion of a coloring agent such as a pigment. Furthermore, when a whole resin is emulsified or suspended in water to prepare a toner mother particle, a sulfonic acid group, may enable the resin to be emulsified or suspended without a surfactant. Examples of such dicarboxylic acids having a sulfonic group include, but are not limited to, sodium 2-sulfoterephthalate, sodium 5-sulfoisophthalate and sodium sulfosuccinate. Furthermore, lower alkyl esters and acid anhydrides of such dicarboxylic acids having a sulfonic group, for example, may also be used. Among these, sodium 5-sulfoisophthalate and the like may be desirable in view of the cost. The content of the dicarboxylic acid having a sulfonic acid group may be from about 0.1% to about 2% by mole percent, in embodiments from about 0.2% by mole to about 1% by mole percent. When the content is more than about 2% by mole percent, the charging properties may be deteriorated. Here, “component mol %” or “component mole %” indicates the percentage when the total amount of each of the components (acid-derived component and alcohol-derived component) in the polyester resin is assumed to be 1 unit (mole).
As to the alcohol component, aliphatic diols may be used. Examples thereof include, but not limited to, ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-dodecanediol, 1,12-undecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol or 1,20-eicosanediol. Among them, those having from about 6 to about 10 carbon atoms may be used to obtain desirable crystal melting points and charging properties. In order to raise crystallinity, it may be useful to use the straight chain diols in an amount of about 95% by mole percent or more, in embodiments about 98% by mole percent or more.
Examples of other dihydric diols which may be utilized include, but are not limited to, bisphenol A, hydrogenated bisphenol A, bisphenol A ethylene oxide adduct, bisphenol A propylene oxide adduct, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, diethylene glycol, propylene glycol, dipropylene glycol, 1,3-butanediol, neopentyl glycol and combinations thereof.
For adjusting the acid number and hydroxyl number, the following may be used: monovalent acids such as acetic acid and benzoic acid; monohydric alcohols such as cyclohexanol and benzyl alcohol; benzenetricarboxylic acid, naphthalenetricarboxylic acid, and anhydrides and lower alkylesters thereof; trivalent alcohols such as glycerin, trimethylolethane, trimethylolpropane, pentaerythritol, and any combinations thereof.
The crystalline polyester resins may be synthesized from a combination of components selected from the above-mentioned monomer components, by using conventional methods. Exemplary methods include the ester exchange method and the direct polycondensation method, which may be used singularly or in a combination thereof. The molar ratio (acid component/alcohol component) when the acid component and alcohol component are reacted, may vary depending on the reaction conditions. The molar ratio is usually about 1/1 in direct polycondensation. In the ester exchange method, a monomer such as ethylene glycol, neopentyl glycol or cyclohexanedimethanol, which may be distilled away under vacuum, may be used in excess.
Surfactants
Any suitable surfactants may be used for the preparation of the latex and wax dispersions according to the present disclosure. Depending on the emulsion system, any desired nonionic or ionic surfactant such as anionic or cationic surfactants may be contemplated.
Examples of suitable anionic surfactants include, but are not limited to, sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, sodium dodecylnaphthalenesulfate, dialkyl benzenealkyl sulfates and sulfonates, abitic acid, NEOGEN R® and NEOGEN SC® available from Kao, Tayca Power®, available from Tayca Corp., DOWFAX®, available from Dow Chemical Co., and the like, as well as mixtures thereof. Anionic surfactants may be employed in any desired or effective amount, for example, at least about 0.01% by weight of total monomers used to prepare the latex polymer, at least about 0.1% by weight of total monomers used to prepare the latex polymer; and no more than about 10% by weight of total monomers used to prepare the latex polymer, no more than about 5% by weight of total monomers used to prepare the latex polymer, although the amount may also be outside of those ranges.
Examples of suitable cationic surfactants include, but are not limited to, dialkyl benzenealkyl ammonium chloride, lauryl trimethyl ammonium chloride, alkylbenzyl methyl ammonium chloride, alkyl benzyl dimethyl ammonium bromide, benzalkonium chloride, cetyl pyridinium bromide, C12, C15 and C17 trimethyl ammonium bromides, halide salts of quaternized polyoxyethylalkylamines, dodecylbenzyl triethyl ammonium chloride, MIRAPOL® and ALKAQUAT® (available from Alkaril Chemical Company), SANIZOL® (benzalkonium chloride, available from Kao Chemicals), and the like, as well as any mixtures thereof.
Examples of suitable nonionic surfactants include, but are not limited to, polyvinyl alcohol, polyacrylic acid, methalose, methyl cellulose, ethyl cellulose, propyl cellulose, hydroxy ethyl cellulose, carboxy methyl cellulose, 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®), and the like, as well as any mixtures thereof.
Initiators
Any suitable initiator or mixture of initiators may be selected in the latex process and the toner process. In embodiments, the initiator is selected from known free radical polymerization initiators. The free radical initiator may be any free radical polymerization initiator capable of initiating a free radical polymerization process or any mixtures thereof, such free radical initiator being capable of providing free radical species on heating to above about 30° C.
Although water soluble free radical initiators are used in emulsion polymerization reactions, other free radical initiators may also be used. Examples of suitable free radical initiators include, but are not limited to, peroxides, such as, ammonium persulfate, hydrogen peroxide, acetyl peroxide, cumyl peroxide, tert-butyl peroxide, propionyl peroxide, benzoyl peroxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, lauroyl peroxide, diisopropyl peroxycarbonate, tetralin hydroperoxide, 1-phenyl-2-methylpropyl-1-hydroperoxide and tert-butylhydroperoxide; pertriphenylacetate, tert-butyl performate; tert-butyl peracetate; tert-butyl perbenzoate; tert-butyl perphenylacetate; tert-butyl permethoxyacetate; tert-butyl per-N-(3-toluyl)carbamate; sodium persulfate; potassium persulfate, azo compounds, such as, 2,2′-azobispropane, 2,2′-dichloro-2,2′-azobispropane, 1,1′-azo(methylethyl)diacetate, 2,2′-azobis(2-amidinopropane)hydrochloride, 2,2′-azobis(2-amidinopropane)-nitrate, 2,2′-azobisisobutane, 2,2′-azobisisobutylamide, 2,2′-azobisisobutyronitrile, methyl 2,2′-azobis-2-methylpropionate, 2,2′-dichloro-2,2′-azobisbutane, 2,2′-azobis-2-methylbutyronitrile, dimethyl 2,2′-azobisisobutyrate, 1,1′-azobis(sodium 1-methylbutyronitrile-3-sulfonate), 2-(4-methylphenylazo)-2-methylmalonod-initrile, 4,4′-azobis-4-cyanovaleric acid, 3,5-dihydroxymethylphenylazo-2-methylmalonodinitrile, 2-(4-bromophenylazo)-2-allylmalonodinitrile, 2,2′-azobis-2-methylvaleronitrile, dimethyl 4,4′-azobis-4-cyanovalerate, 2,2′-azobis-2,4-dimethylvaleronitrile, 1,1′-azobiscyclohexanenitrile, 2,2′-azobis-2-propylbutyronitrile, 1,1′-azobis-1-chlorophenylethane, 1,1′-azobis-1-cyclohexanecarbonitrile, 1,1′-azobis-1-cycloheptanenitrile, 1,1′-azobis-1-phenylethane, 1,1′-azobiscumene, ethyl 4-nitrophenylazobenzylcyanoacetate, phenylazodiphenylmethane, phenylazotriphenylmethane, 4-nitrophenylazotriphenylmethane, 1′-azobis-1,2-diphenylethane, poly(bisphenol A-4,4′-azobis-4-cyanopentano-ate) and poly(tetraethylene glycol-2,2′-azobisisobutyrate); 1,4-bis(pentaethylene)-2-tetrazene; 1,4-dimethoxycarbonyl-1,4-dipheny-1-2-tetrazene, and the like; or any mixtures thereof.
More typical free radical initiators include, but are not limited to, ammonium persulfate, hydrogen peroxide, acetyl peroxide, cumyl peroxide, tert-butyl peroxide, propionyl peroxide, benzoyl peroxide, chlorobenzoyl peroxide, dichlorobenzoyl peroxide, bromomethylbenzoyl peroxide, lauroyl peroxide, sodium persulfate, potassium persulfate, diisopropyl peroxycarbonate, and the like, or combinations thereof.
Based on total weight of the monomers to be polymerized, the initiator may be present in an amount from about 0.1% to about 5%, from about 0.4% to about 4%, from about 0.5% to about 3%, although may be present in greater or lesser amounts.
Chain Transfer Agent
A chain transfer agent optionally may be used to control the polymerization degree of the latex, and thereby control the molecular weight and molecular weight distribution of the product latexes of the latex process and/or the toner process according to the present disclosure. As can be appreciated, a chain transfer agent may become part of the latex polymer.
In embodiments, the chain transfer agent has a carbon-sulfur covalent bond. The carbon-sulfur covalent bond may have an absorption peak in a wave number region ranging from 500 to 800 cm−1 in an infrared absorption spectrum. When the chain transfer agent is incorporated into the latex and the toner made from the latex, the absorption peak may be changed, for example, to a wave number region of 400 to 4,000 cm−1.
Exemplary chain transfer agents include, but are not limited to, n-C3-15 alkyl mercaptans, such as, n-propylmercaptan, n-butylmercaptan, n-amylmercaptan, n-hexylmercaptan, n-heptylmercaptan, n-octylmercaptan, n-nonylmercaptan, n-decylmercaptan and n-dodecylmercaptan; branched alkylmercaptans, such as, isopropylmercaptan, isobutylmercaptan, s-butylmercaptan, tert-butylmercaptan, cyclohexylmercaptan, tert-hexadecylmercaptan, tert-laurylmercaptan, tert-nonylmercaptan, tert-octylmercaptan and tert-tetradecylmercaptan; aromatic ring-containing mercaptans, such as, allylmercaptan, 3-phenylpropylmercaptan, phenylmercaptan and mercaptotriphenylmethane; and so on. The terms, mercaptan and thiol may be used interchangeably to mean C—SH group.
Examples of such chain transfer agents also include, but are not limited to, dodecanethiol, butanethiol, isooctyl-3-mercaptopropionate, 2-methyl-5-t-butyl-thiophenol, carbon tetrachloride, carbon tetrabromide, and the like, or any combinations thereof.
Based on total weight of the monomers to be polymerized, the chain transfer agent may be present in an amount from about 0.1% to about 7%, from about 0.5% to about 6%, from about 1.0% to about 5%, although may be present in greater or lesser amounts.
In embodiments, a branching agent optionally may be included in the first/second monomer composition to control the branching structure of the target latex. Exemplary branching agents include, but are not limited to, decanediol diacrylate (ADOD), trimethylolpropane, pentaerythritol, trimellitic acid, pyromellitic acid or any mixtures thereof.
Based on total weight of the monomers to be polymerized, the branching agent may be present in an amount from about 0% to about 2%, from about 0.05% to about 1.0%, from about 0.1% to about 0.8%, although may be present in greater or lesser amounts.
In the latex process and toner process of the disclosure, emulsification may be done by any suitable process, such as, mixing at elevated temperature. For example, the emulsion mixture may be mixed in a homogenizer set at about 200 to about 400 rpm and at a temperature of from about 40° C. to about 80° C. for a period of from about 1 min to about 20 min.
Any type of reactor may be used without restriction. The reactor may include means for stirring the compositions therein, such as, an impeller. A reactor may include at least one impeller. For forming the latex and/or toner, the reactor may be operated throughout the process such that the impellers may operate at an effective mixing rate of about 10 to about 1,000 rpm.
Following completion of the monomer addition, the latex may be permitted to stabilize by maintaining the conditions for a period of time, for example for about 10 min to about 300 min, before cooling. Optionally, the latex formed by the above process may be isolated by standard methods known in the art, for example, coagulation, dissolution and precipitation, filtering, washing, drying or the like.
The latex of the present disclosure may be selected for emulsion-aggregation-coalescence processes for forming toners and developers by known methods. The latex of the present disclosure may be melt blended or otherwise mixed with various toner ingredients, such as, a wax dispersion, a coagulant, an optional silica, an optional charge enhancing additive or charge control agent, an optional surfactant, an optional emulsifier, an optional flow additive and the like. Optionally, the latex (e.g. around 40% by weight solids) may be diluted to the desired solids loading (e.g. about 12 to about 15% by weight solids), before being formulated in a toner composition.
Based on the total toner weight, the latex may be present in an amount from about 50% to about 100%, from about 60% to about 98%, from about 70% to about 95%, although may be present in greater or lesser amounts.
Colorants
Various known suitable colorants, such as dyes, pigments, mixtures of dyes, mixtures of pigments, mixtures of dyes and pigments and the like may be included in the toner. The colorant may be included in the toner in an amount of, for example, about 0.1 to about 35% by weight of the toner, from about 1 to about 15% percent of the toner, from about 3 to about 10% by weight of the toner, although amounts outside those ranges may be utilized.
As examples of suitable colorants, mention may be made of carbon black like REGAL 330®; magnetites, such as, Mobay magnetites MO8029™ and MO8060™; Columbian magnetites; MAPICO BLACKS™, surface-treated magnetites; Pfizer magnetites CB4799™, CB5300™, CB5600™ and MCX6369™; Bayer magnetites, BAYFERROX 8600™ and 8610™; Northern Pigments magnetites, NP-604™ and NP-608™; Magnox magnetites TMB-100™ or TMB-104™; and the like. As colored pigments, there may be selected cyan, magenta, yellow, red, green, brown, blue or mixtures thereof. Generally, cyan, magenta or yellow pigments or dyes, or mixtures thereof, are used. The pigment or pigments may be water-based pigment dispersions.
Specific examples of pigments include, but are not limited to, SUNSPERSE 6000, FLEXIVERSE and AQUATONE water-based pigment dispersions from SUN Chemicals, HELIOGEN BLUE L6900™, D6840™, D7080™, D7020™, PYLAM OIL BLUE™, PYLAM OIL YELLOW™, PIGMENT BLUE I™ available from Paul Uhlich & Company, Inc., PIGMENT VIOLET 1™, PIGMENT RED 48™, LEMON CHROME YELLOW DCC 1026™, E.D. TOLUIDINE RED™ and BON RED C™ available from Dominion Color Corporation, Ltd., Toronto, Ontario, NOVAPERM YELLOW FGL™, HOSTAPERM PINK E™ available from Hoechst, CINQUASIA MAGENTA™ available from E.I. DuPont de Nemours & Company and the like. Colorants that may be selected are black, cyan, magenta, yellow and mixtures thereof. Examples of magentas include, but are not limited to, 2,9-dimethyl-substituted quinacridone and anthraquinone dye identified in the Color Index as CI 60710, CI Dispersed Red 15, diazo dye identified in the Color Index as CI 26050, CI Solvent Red 19, and the like. Illustrative examples of cyans include, but are not limited to, copper tetra(octadecyl sulfonamido) phthalocyanine, x-copper phthalocyanine pigment listed in the Color Index as CI 74160, CI Pigment Blue, Pigment Blue 15:3, Anthrathrene Blue, identified in the Color Index as CI 69810, Special Blue X-2137 and the like. Illustrative examples of yellows include, but are not limited to, diarylide yellow 3,3-dichlorobenzidene acetoacetanilides, a monoazo pigment identified in the Color Index as CI 12700, CI Solvent Yellow 16, a nitrophenyl amine sulfonamide identified in the Color Index as Foron Yellow SE/GLN, CI Dispersed Yellow 33 2,5-dimethoxy-4-sulfonanilide phenylazo-4′-chloro-2,5-dimethoxy acetoacetanilide and Permanent Yellow FGL. Colored magnetites, such as, mixtures of MAPICO BLACK™, and cyan components also may be selected as colorants. Other known colorants may be selected, such as, Levanyl Black A-SF (Miles, Bayer) and Sunsperse Carbon Black LHD 9303 (Sun Chemicals), and colored dyes, such as, Neopen Blue (BASF), Sudan Blue OS (BASF), PV Fast Blue B2G01 (American Hoechst), Sunsperse Blue BHD 6000 (Sun Chemicals), Irgalite Blue BCA (Ciba-Geigy), Paliogen Blue 6470 (BASF), Sudan III (Matheson, Coleman, Bell), Sudan II (Matheson, Coleman, Bell), Sudan IV (Matheson, Coleman, Bell), Sudan Orange G (Aldrich), Sudan Orange 220 (BASF), Paliogen Orange 3040 (BASF), Ortho Orange OR 2673 (Paul Uhlich), Paliogen Yellow 152, 1560 (BASF), Lithol Fast Yellow 0991K (BASF), Paliotol Yellow 1840 (BASF), Neopen Yellow (BASF), Novoperm Yellow FG 1 (Hoechst), Permanent Yellow YE 0305 (Paul Uhlich), Lumogen Yellow D0790 (BASF), Sunsperse Yellow YHD 6001 (Sun Chemicals), Suco-Gelb L1250 (BASF), Suco-Yellow D1355 (BASF), Hostaperm Pink E (American Hoechst), Fanal Pink D4830 (BASF), Cinquasia Magenta (DuPont), Lithol Scarlet D3700 (BASF), Toluidine Red (Aldrich), Scarlet for Thermoplast NSD PS PA (Ugine Kuhlmann of Canada), E.D. Toluidine Red (Aldrich), Lithol Rubine Toner (Paul Uhlich), Lithol Scarlet 4440 (BASF), Bon Red C (Dominion Color Company), Royal Brilliant Red RD-8192 (Paul Uhlich), Oracet Pink RF (Ciba-Geigy), Paliogen Red 3871K (BASF), Paliogen Red 3340 (BASF), Lithol Fast Scarlet L4300 (BASF), any combinations of the foregoing, and the like.
Wax
In addition to the polymer resin, the toners of the present disclosure also may contain a wax, which may be either a single type of wax or a mixture of two or more different waxes. A single wax may be added to toner compositions, for example, to improve particular toner properties, such as, toner particle shape, presence and amount of wax on the toner particle surface, charging and/or fusing characteristics, gloss, stripping, offset properties and the like. Alternatively, a combination of waxes may be added to provide multiple properties to the toner composition.
When included, the wax may be present in an amount of, for example, from about 1 wt % to about 25 wt % of the toner particles, in embodiments, from about 5 wt % to about 20 wt % of the toner particles.
Waxes that may be selected include waxes having, for example, a weight average molecular weight of from about 500 to about 20,000, in embodiments from about 1,000 to about 10,000. Waxes that may be used include, for example, polyolefins, such as, polyethylene, polypropylene and polybutene waxes, such as, commercially available from Allied Chemical and Petrolite Corporation, for example POLYWAX™ polyethylene waxes from Baker Petrolite, wax emulsions available from Michaelman, Inc. and the Daniels Products Company, EPOLENE N-15™ commercially available from Eastman Chemical Products, Inc., and VISCOL 550-P™, a low weight average molecular weight polypropylene available from Sanyo Kasei K. K.; plant-based waxes, such as, carnauba wax, rice wax, candelilla wax, sumacs wax and jojoba oil; animal-based waxes, such as, beeswax; mineral-based waxes and petroleum-based waxes, such as, montan wax, ozokerite, ceresin, paraffin wax, microcrystalline wax and Fischer-Tropsch wax; ester waxes obtained from higher fatty acid and higher alcohol, such as, stearyl stearate and behenyl behenate; ester waxes obtained from higher fatty acid and monovalent or multivalent lower alcohol, such as, butyl stearate, propyl oleate, glyceride monostearate, glyceride distearate, pentaerythritol tetra behenate; ester waxes obtained from higher fatty acid and multivalent alcohol multimers, such as, diethyleneglycol monostearate, dipropyleneglycol distearate, diglyceryl distearate and triglyceryl tetrastearate; sorbitan higher fatty acid ester waxes, such as, sorbitan monostearate, and cholesterol higher fatty acid ester waxes, such as, cholesteryl stearate. Examples of functionalized waxes that may be used include, for example, amines, amides, for example, AQUA SUPERSLIP 6550™ and SUPERSLIP 6530™ available from Micro Powder Inc., fluorinated waxes, for example, POLYFLUO 190™, POLYFLUO 200™, POLYSILK 19™ and POLYSILK 14™ available from Micro Powder Inc., mixed fluorinated, amide waxes, for example, MICROSPERSION 19™ available from Micro Powder Inc., imides, esters, quaternary amines, carboxylic acids or acrylic polymer emulsion, for example JONCRYL 74™, 89™, 130™, 537™ and 538™, all available from SC Johnson Wax, and chlorinated polypropylenes and polyethylenes available from Allied Chemical and Petrolite Corporation and SC Johnson wax, Mixtures and combinations of the foregoing waxes also may be used in embodiments. Waxes may be included as, for example, fuser roll release agents.
Charge Control Agent (CCA)
A charge control agent may be incorporated into the surface additive. In embodiments, the charge control agent is a metal charge control agent having a metal such zinc, aluminum, calcium, chromium and iron. In embodiments, the charge control agent is is 3,5 di-tert-butylsalicyclic acid zinc salt. Suitable zinc charge control agents include BONTRON E-84™, BONTRON E-84S™ or BONTRON E-304™ (Hodogaya Chemical) and similar zinc salts. In embodiments, charge control agents aluminum salts such as BONTRON E-108™ or BONTRON E-108W™ (Hodogaya Chemical) are suitable. In embodiments, charge control agents or an iron complex such as BONTRON X-11™ (Hodogaya Chemical) are suitable. The charge control agent can include combinations of those listed above. In embodiments, charge control agents or an chromium complex such as BONTRON E-81™ or BONTRON S-34™ (Hodogaya Chemical) are suitable. The charge control agent can include combinations of those listed above. The charge control agent particle size can be adjusted, in embodiments, to a particle size of from about 50 to about 500, or from about 150 to about 300, or from about 175 to about 275 nm. In embodiments, the CCA and the silicone oil can be reversed in nucleophilic and electrophilic capacity. For example, the silicone oil can be modified to display a nucleophilic amino group and subsequently this amino group can be alkylated to generate quaternary ammonium salts.
The charge control agent can be incorporated into the core of the particle, the shell of the particle or a combination of both. If placing in the core and both, the CCA is added during homogenization but just before the addition of the coagulating agent. The mixture is then homogenized according to procedure and then the batch is heated, aggregated and coalesced. If adding to the shell or both the core and shell, the CCA should be added to the shell latex first before shell addition. The shell mixture is added via pump until complete. The process then proceeds similar to the control sample. The charge control agent is present in the toner in an amount of from about 0.1 to about 3, or from about 0.3 to 2 or from about 0.3 to 1 percent by weight of total solids.
Incorporation of the CCA into the toners with silicon tetrachloride (SiCl4) may be used as the toner additive and the toner formulation.
Toner Preparation
The toner particles may be prepared by any method within the purview of one skilled in the art. Although embodiments relating to toner particle production are described below with respect to emulsion-aggregation processes, any suitable method of preparing toner particles may be used, including chemical processes, such as suspension and encapsulation processes disclosed in U.S. Pat. Nos. 5,290,654 and 5,302,486, the disclosure of each of which hereby is incorporated by reference in entirety. In embodiments, toner compositions and toner particles may be prepared by aggregation and coalescence processes in which smaller-sized resin particles are aggregated to the appropriate toner particle size and then coalesced to achieve the final toner particle shape and morphology.
In embodiments, toner compositions may be prepared by emulsion-aggregation processes, such as, a process that includes aggregating a mixture of an optional wax and any other desired or required additives, and emulsions including the resins described above, optionally with surfactants, as described above, and then coalescing the aggregate mixture. A mixture may be prepared by adding an optional wax or other materials, which optionally also may be in a dispersion(s) including a surfactant, to the emulsion, which may be a mixture of two or more emulsions containing the resin. The pH of the resulting mixture may be adjusted by an acid (i.e., a pH adjustor) such as, for example, acetic acid, nitric acid, or the like. In embodiments, the pH of the mixture may be adjusted to from about 2 to about 4.5. Additionally, in embodiments, the mixture may be homogenized. If the mixture is homogenized, homogenization may be accomplished by mixing at about 600 to about 4,000 revolutions per minute (rpm). Homogenization may be accomplished by any suitable means, including, for example, with an IKA ULTRA TURRAX T50 probe homogenizer.
Following preparation of the above mixture, an aggregating agent may be added to the mixture. Suitable aggregating agents include, for example, aqueous solutions of a divalent cation or a multivalent cation material. The aggregating agent may include, but are not limited to, polyaluminum halides, such as, polyaluminum chloride (PAC), or the corresponding bromide, fluoride or iodide, polyaluminum silicates, such as, polyaluminum sulfosilicate (PASS), and water soluble metal salts including aluminum chloride, aluminum nitrite, aluminum sulfate, potassium aluminum sulfate, calcium acetate, calcium chloride, calcium nitrite, calcium oxylate, calcium sulfate, magnesium acetate, magnesium nitrate, magnesium sulfate, zinc acetate, zinc nitrate, zinc sulfate, zinc chloride, zinc bromide, magnesium bromide, copper chloride, copper sulfate, or any combinations thereof. In embodiments, the aggregating agent may be added to the mixture at a temperature that is below the glass transition temperature (Tg) of the resin.
The aggregating agent may be added to the mixture to form a toner in an amount of, for example, from about 0.1 parts per hundred (pph) to about 1 pph, in embodiments, from about 0.25 pph to about 0.75 pph.
The gloss of a toner may be influenced by the amount of retained metal ion, such as, Al3+, in the toner particles. The amount of retained metal ion may be adjusted further by the addition of ethylene diamine tetraacetic acid (EDTA). In embodiments, the amount of retained metal ion, for example, Al3+, in toner particles of the present disclosure may be from about 0.1 pph to about 1 pph, in embodiments, from about 0.25 pph to about 0.8 pph.
The disclosure also provides a melt mixing process to produce low cost and safe cross-linked thermoplastic binder resins for toner compositions which have, for example, low fix temperature and/or high offset temperature, and which may show minimized or substantially no vinyl offset. In the process, unsaturated base polyester, resins or polymers are melt blended, that is, in the molten state under high shear conditions producing substantially uniformly dispersed toner constituents, and which process provides a resin blend and toner product with optimized gloss properties (see, e.g., U.S. Pat. No. 5,556,732, herein incorporated by reference in entirety). By, “highly cross-linked,” is meant that the polymer involved is substantially cross-linked, that is, equal to or above the gel point. As used herein, “gel point” means the point where the polymer is no longer soluble in solution (see, e.g., U.S. Pat. No. 4,457,998, herein incorporated by reference in its entirety).
To control aggregation and coalescence of the particles, in embodiments, the aggregating agent may be metered into the mixture over time. For example, the agent may be metered into the mixture over a period of from about 5 min to about 240 min, in embodiments, from about 30 min to about 200 min. Addition of the agent may also be done while the mixture is maintained under stirred conditions, in embodiments from about 50 rpm to about 1,000 rpm, in embodiments, from about 100 rpm to about 500 rpm, and at a temperature that is below the Tg of the resin.
The particles may be permitted to aggregate until a predetermined desired particle size is obtained. A predetermined desired size refers to the desired particle size as determined prior to formation, with particle size monitored during the growth process as known in the art until such particle size is achieved. Samples may be taken during the growth process and analyzed, for example with a Coulter Counter, for average particle size. The aggregation thus may proceed by maintaining the elevated temperature, or slowly raising the temperature to, for example, from about 40° C. to about 100° C., and holding the mixture at that temperature for a time from about 0.5 hr to about 6 hr, in embodiments, from about 1 hr to about 5 hr, while maintaining stirring, to provide the aggregated particles. Once the predetermined desired particle size is obtained, the growth process is halted. In embodiments, the predetermined desired particle size is within the toner particle size ranges mentioned above. In embodiments, the particle size may be about 5.0 to about 6.0 μm, about 6.0 to about 6.5 μm, about 6.5 to about 7.0 μm, about 7.0 to about 7.5 μm.
Growth and shaping of the particles following addition of the aggregation agent may be accomplished under any suitable conditions. For example, the growth and shaping may be conducted under conditions in which aggregation occurs separate from coalescence. For separate aggregation and coalescence stages, the aggregation process may be conducted under shearing conditions at an elevated temperature, for example from about 40° C. to about 90° C., in embodiments, from about 45° C. to about 80° C., which may be below the Tg of the resin.
Toners may possess favorable charging characteristics when exposed to extreme RH conditions, The low humidity zone (C zone) may be about 12° C./15% RH, while the high humidity zone (A zone) may be about 28° C./85% RH. Toners of the disclosure may possess a parent toner charge per mass ratio (Q/M) of from about −5 μC/g to about −80 μC/g, in embodiments, from about −10 μC/g to about −70 μC/g, and a final toner charging after surface additive blending of from −15 μC/g to about −60 μC/g, in embodiments, from about −20 μC/g to about −55 μC/g.
Shell Resin
In embodiments, a shell may be applied to the formed aggregated toner particles. Any resin described above as suitable for the core resin may be utilized as the shell resin. The shell resin may be applied to the aggregated particles by any method within the purview of those skilled in the art. In embodiments, the shell resin may be in an emulsion including any surfactant described herein. The aggregated particles described above may be combined with said emulsion so that the resin forms a shell over the formed aggregates. In embodiments, an amorphous polyester may be utilized to form a shell over the aggregates to form toner particles having a core-shell configuration.
Toner particles may have a size of diameter of from about 4 to about 8 μm, in embodiments, from about 5 μm to about 7 μm, the optimal shell component may be about 26% to about 30% by weight of the toner particles.
Alternatively, a thicker shell may be desirable to provide desirable charging characteristics due to the higher surface area of the toner particle. Thus, the shell resin may be present in an amount from about 30% to about 40% by weight of the toner particles, in embodiments, from about 32% to about 38% by weight of the toner particles, in embodiments, from about 34% to about 36% by weight of the toner particles.
In embodiments, a photoinitiator may be included in the shell. Thus, the photoinitiator may be in the core, the shell, or both. The photoinitiator may be present in an amount of from about 1% to about 5% by weight of the toner particles, in embodiments, from about 2% to about 4% by weight of the toner particles.
Emulsions may have a solids loading of from about 5% solids by weight to about 20% solids by weight, in embodiments, from about 12% solids by weight to about 17% solids by weight.
Once the desired final size of the toner particles is achieved, the pH of the mixture may be adjusted with a base (i.e., a pH adjustor) to a value of from about 6 to about 10, and in embodiments from about 6.2 to about 7. The adjustment of the pH may be utilized to freeze, that is to stop, toner growth. The base utilized to stop toner growth may include any suitable base, such as, for example, alkali metal hydroxides, such as, for example, sodium hydroxide, potassium hydroxide, ammonium hydroxide, or any combinations thereof and the like. In embodiments, EDTA may be added to help adjust the pH to the desired values noted above. The base may be added in amounts from about 2 to about 25% by weight of the mixture, in embodiments, from about 4 to about 10% by weight of the mixture. In embodiments, the shell has a higher Tg than the aggregated toner particles.
Coalescence
Following aggregation to the desired particle size, with the optional formation of a shell as described above, the particles then may be coalesced to the desired final shape. The coalescence may be achieved by, for example, heating the mixture to a temperature of from about 55° C. to about 100° C., in embodiments from about 65° C. to about 75° C., which may be below the melting point of a crystalline resin to prevent plasticization. Higher or lower temperatures may be used, it being understood that the temperature is a function of the resins used.
Coalescence may proceed over a period of from about 0.1 hr to about 9 hr, in embodiments, from about 0.5 hr to about 4 hr.
After coalescence, the mixture may be cooled to room temperature, such as from about 20° C. to about 25° C. The cooling may be rapid or slow, as desired. A suitable cooling method may include introducing cold water to a jacket around the reactor. After cooling, the toner particles optionally may be washed with water and then dried. Drying may be accomplished by any suitable method, for example, freeze drying.
Carriers
Various suitable solid core or particle materials may be utilized for the carriers and developers of the present disclosure. Characteristic particle properties include those that, in embodiments, will enable the toner particles to acquire a positive charge or a negative charge, and carrier cores that provide desirable flow properties in the developer reservoir present in an electrophotographic imaging apparatus. Other desirable properties of the core include, for example, suitable magnetic characteristics that permit magnetic brush formation in magnetic brush development processes; desirable mechanical aging characteristics; and desirable surface morphology to permit high electrical conductivity of any developer including the carrier and a suitable toner.
Examples of carrier particles or cores that may be utilized include, but are not limited to, iron and/or steel, such as, atomized iron or steel powders available from Hoeganaes Corporation or Pomaton S.p.A (Italy); ferrites, such as, Cu/Zn-ferrite containing, for example, about 11% copper oxide, about 19% zinc oxide, and about 70% iron oxide, including those commercially available from D.M. Steward Corporation or Powdertech Corporation, Ni/Zn-ferrite available from Powdertech Corporation, Sr (strontium)-ferrite, containing, for example, about 14% strontium oxide and about 86% iron oxide, commercially available from Powdertech Corporation, and Ba-ferrite; magnetites, including those commercially available from, for example, Hoeganaes Corporation (Sweden); nickel; combinations thereof, and the like. In embodiments, the polymer particles obtained may be used to coat carrier cores of any known type by various known methods, and which carriers then are incorporated with a known toner to form a developer for electrophotographic printing. Other suitable carrier cores are illustrated in, for example, U.S. Pat. Nos. 4,937,166, 4,935,326 and 7,014,971, the disclosure of each of which is hereby incorporated by reference in entirety, and may include granular zircon, granular silicon, glass, silicon dioxide, combinations thereof, and the like. In embodiments, suitable carrier cores may have an average particle size of, for example, from about 20 μm to about 400 μm in diameter, in embodiments, from about 40 μm to about 200 μm in diameter.
In embodiments, a ferrite may be utilized as the core, including a metal, such as, iron and at least one additional metal, such as, copper, zinc, nickel, manganese, magnesium, calcium, lithium, strontium, zirconium, titanium, tantalum, bismuth, sodium, potassium, rubidium, cesium, strontium, barium, yttrium, lanthanum, hafnium, vanadium, niobium, aluminum, gallium, silicon, germamium, antimony, or any combinations thereof and the like.
In embodiments, a developer is disclosed including a resin coated carrier and a toner, where the toner may be an emulsion aggregation toner containing, but not limited to, a latex resin, a wax and/or a polymer shell.
Conductive Component
In some embodiments, the carrier coating may include a conductive component. Suitable conductive components include, for example, carbon black.
There may be added to the carrier a number of additives, for example, charge enhancing additives, including particulate amine resins, such as, melamine, and certain fluoropolymer powders, such as alkyl-amino acrylates and methacrylates, polyamides, and fluorinated polymers, such as polyvinylidine fluoride and poly(tetrafluoroethylene) and fluoroalkyl methacrylates, such as 2,2,2-trifluoroethyl methacrylate. Other charge enhancing additives which may be utilized include quaternary ammonium salts, including distearyl dimethyl ammonium methyl sulfate (DDAMS), bis[1-[(3,5-disubstituted-2-hydroxyphenypazo]-3-(mono-substituted)-2-naph-thalenolato(2-)]chromate(1-), ammonium sodium and hydrogen (TRH), cetyl pyridinium chloride (CPC), FANAL PINK® D4830, or any combinations thereof, and the like, and/or other effective known charge agents or additives. The charge additive components may be selected in various effective amounts, such as from about 0.5 wt % to about 20 wt %, from about 1 wt % to about 3 wt %, based, for example, on the sum of the weights of polymer/copolymer, conductive component, and other charge additive components. The addition of conductive components may act to further increase the negative triboelectric charge imparted to the carrier, and therefore, further increase the negative triboelectric charge imparted to the toner in, for example, an electrophotographic development subsystem. The components may be included by roll mixing, tumbling, milling, shaking, electrostatic powder cloud spraying, fluidized bed, electrostatic disc processing, and an electrostatic curtain, as described, for example, in U.S. Pat. No. 6,042,981, the disclosure of which is hereby incorporated by reference in entirety, and wherein the carrier coating is fused to the carrier core in either a rotary kiln or by passing through a heated extruder apparatus.
Conductivity can be important for semiconductive magnetic brush development to enable good development of solid areas which otherwise may be weakly developed. Addition of a polymeric coating of the present disclosure, optionally with a conductive component such as carbon black, may result in carriers with decreased developer triboelectric response with change in relative humidity from about 20% to about 90%, in embodiments, from about 40% to about 80%, that the charge is more consistent when the relative humidity is changed. Thus, there is less decrease in charge at high relative humidity reducing background toner on the prints, and less increase in charge and subsequently less loss of development at low relative humidity, resulting in such improved image quality performance due to improved optical density.
As noted above, in embodiments the polymeric coating may be dried, after which time it may be applied to the core carrier as a dry powder. Powder coating processes differ from conventional solution coating processes. Solution coating requires a coating polymer whose composition and molecular weight properties enable the resin to be soluble in a solvent in the coating process. That requires relatively low Mw components as compared to powder coating. The powder coating process does not require solvent solubility, but does require the resin coated as a particulate with a particle size of from about 10 nm to about 2 μm, in embodiments, from about 30 nm to about 1 μm, in embodiments, from about 50 nm to about 500 nm.
Examples of processes which may be utilized to apply the powder coating include, for example, combining the carrier core material and resin coating by cascade roll mixing, tumbling, milling, shaking, electrostatic powder cloud spraying, fluidized bed, electrostatic disc processing, electrostatic curtains, combinations thereof and the like. When resin coated carrier particles are prepared by a powder coating process, the majority of the coating materials may be fused to the carrier surface, thereby reducing the number of toner impaction sites on the carrier. Fusing of the polymeric coating may occur by mechanical impaction, electrostatic attraction, or any combinations thereof and the like.
Following application of the resin to the core, heating may be initiated to permit flow of the coating material over the surface of the carrier core. The concentration of the coating material, in embodiments, powder particles, and the parameters of the heating may be selected to enable the formation of a continuous film of the coating polymers on the surface of the carrier core, or permit only selected areas of the carrier core to be coated. In embodiments, the carrier with the polymeric powder coating may be heated to a temperature of from about 170° C. to about 280° C., in embodiments from about 190° C. to about 240° C., for a period of time, for example, from about 10 min to about 180 min, in embodiments, from about 15 min to about 60 min, to enable the polymer coating to melt and to fuse to the carrier core particles. Following incorporation of the powder on the surface of the carrier, heating may be initiated to permit flow of the coating material over the surface of the carrier core. In embodiments, the powder may be fused to the carrier core in either a rotary kiln or by passing through a heated extruder apparatus, see, for example, U.S. Pat. No. 6,355,391, the disclosure of which is hereby incorporated by reference in entirety.
In embodiments, the coating coverage encompasses from about 10% to about 100% of the carrier core. When selected areas of the metal carrier core remain uncoated or exposed, the carrier particles may possess electrically conductive properties when the core material is a metal.
The coated carrier particles may then be cooled, in embodiments to room temperature, and recovered for use in forming developer.
In embodiments, carriers of the present disclosure may include a core, in embodiments, a ferrite core, having a size of from about 20 μm to about 100 μm, in embodiments, from about 30 μm to about 75 μm, coated with from about 0.5% to about 10% by weight, in embodiments, from about 0.7% to about 5% by weight, of the polymer coating of the present disclosure, optionally including carbon black.
Thus, with the carrier compositions and processes of the present disclosure, there may be formulated developers with selected high triboelectric charging characteristics and/or conductivity values utilizing a number of different combinations.
Developers
The toner particles thus formed may be formulated into a developer composition. The toner particles may be mixed with carrier particles to achieve a two component developer composition. The toner concentration in the developer may be from about 1% to about 25% by weight of the total weight of the developer, in embodiments, from about 2% to about 15% by weight of the total weight of the developer.
Imaging
The toners may be utilized for electrophotographic processes, including those disclosed in U.S. Pat. No. 4,295,990, the disclosure of which is hereby incorporated by reference in entirety. In embodiments, any known type of image development system may be used in an image developing device, including, for example, magnetic brush development, hybrid scavengeless development (HSD) and the like. These and similar development systems are within the purview of those skilled in the art.
It is envisioned that the toners of the present disclosure may be used in any suitable procedure for forming an image with a toner, including in applications other than xerographic applications.
Utilizing the toners of the present disclosure, images may be formed on substrates, including flexible substrates, having a toner pile height of from about 1 μm to about 6 μm, in embodiments, from about 2 μm to about 4.5 μm, in embodiments, from about 2.5 μm to about 4.2 μm.
In embodiments, the toner of the present disclosure may be used for a xerographic print protective composition that provides overprint coating properties including, but not limited to, thermal and light stability and smear resistance, particularly in commercial print applications. More specifically, such overprint coating as envisioned has the ability to permit overwriting, reduce or prevent thermal cracking, improve fusing, reduce or prevent document offset, improve print performance and protect an image from sun, heat and the like. In embodiments, the overprint compositions may be used to improve the overall appearance of xerographic prints due to the ability of the compositions to fill in the roughness of xerographic substrates and toners, thereby forming a level film and enhancing glossiness.
The examples set forth herein below are being submitted to illustrate embodiments of the present disclosure. These examples are intended to be illustrative only and are not intended to limit the scope of the present disclosure. Also, parts and percentages are by weight unless otherwise indicated. Comparative examples and data are also provided.
The following Examples are being submitted to further define various species of the present disclosure. These Examples are intended to be illustrative only and are not intended to limit the scope of the present disclosure. Also, parts and percentages are by weight unless otherwise indicated.
5 grams of silica gel powder (SiO2, Sigma Aldrich 236772) was mixed with 3 mL of silicon tetrachloride (SiCl4) in methylene chloride solvent to form a dispersion. To this dispersion was added 2 grams of ZnCCA (BONTRON E-108™ phenolic zinc organometallic) solution in tetrahydrofuran and the mixture stirred at room temperature for several hours. The filtered and dried powder, 4.5 g., was physically mixed with 45 g. of SrTiO3 and thoroughly ground by mortar and pestle.
The SiO2/SiCl4/Zn CCA treated SrTiO3 described in Example 1 was blended at 0.2 pph and 0.4 pph, along with the standard toner additive package including titania, small/medium silica, large colloidal silica, and zinc stearate was blended with cyan toner particle in a 10-liter blender for 10 minutes at 3000 rpm.
Criteria for triboelectric performance: Seeing a large effect with most dry environment while not seeing it in wet is preferable.
The SrTiO3 at 0.2 pph and 0.4 pph with the SiCl4 binding to Zn charge control agent, along with the standard additive package including titania, small/medium silica, large colloidal silica, and zinc stearate was blended with cyan toner particle in a 10-liter blender for 10 minutes at 3000 rpm.
Triboelectric characteristics of the resulting toner blend was measured at various humidity conditions: nominal, (70° F. (21° C.)/50% RH), dry (70° F. (21° C.)/10% RH), and wet (80° F. (27° C.)/80% RH) and is shown in
The SiO2/SiCl4/Zn CCA treated SrTiO3 at 50% of the typical titania loading and 100% of the typical titania loading, along with the standard additive package including small/medium silica, large colloidal silica, and zinc stearate was blended with cyan toner particle (conditions). No titania were included in these blends. As shown in
It will be appreciated that various embodiments of the above-disclosed and other features and functions, or alternatives thereof, may be desirably combined into many other different systems or applications. Also that various presently unforeseen or unanticipated alternatives, modifications, variations or improvements therein may be subsequently made by those skilled in the art which are also intended to be encompassed by the following claims. Unless specifically recited in a claim, steps or components of claims should not be implied or imported from the specification or any other claims as to any particular order, number, position, size, shape, angle, color, or material.
| Number | Name | Date | Kind |
|---|---|---|---|
| 5482741 | Law | Jan 1996 | A |
| 20100239971 | Moriya | Sep 2010 | A1 |
