Patent Application
20150010861
Hyperpigmented toner, such as, a black toner, containing a set of insulative second colorants in addition to the primary colorant, such as, a black colorant, with reduced dielectric loss as compared to a hyperpigmented toner containing only the primary colorant; developers comprising said hyperpigmented toner; devices comprising the hyperpigmented toner and developers; imaging device components comprising the hyperpigmented toner and developers; imaging devices comprising the developers; and so on, are described.
Black color materials used in an electrophotographic toner and in an ink for inkjet printing include carbon black, aniline black, black iron oxide, black titanium oxide and the like. Carbon black is an organic pigment having high color density (coloring per unit weight), high blackness degree and high light fastness. In efforts to increase pigment loading, toners containing a black pigment often exhibit lower charging with high dielectric loss, both of which reduce transfer efficiency and degrade image quality. Black pigments are conductive and can form conductive pathways through a toner particle. Therefore, there remains a need to reduce the dielectric loss, and thus, improve charging to enable lower cost hyperpigmented toner.
The present disclosure describes hyperpigmented toner compositions comprising a first or primary colorant and further comprising two or more additional or secondary colorants, which toners exhibit reduced dielectric loss and match or exceed the performance of prior toners or hyperpigmented toners with only the first colorant, such as, a black colorant. The two or more additional, second or secondary colorants generally are of a color different from that of the first colorant.
In embodiments, a toner composition is disclosed including a first amorphous emulsion, an optional second amorphous emulsion, an optional crystalline emulsion, a surfactant, an optional wax, optionally a shell, a first colorant, and a mixture of two or more second colorants, where in the presence of the mixture, the toner exhibits lower dielectric loss as compared to a toner in the absence of the mixture.
In embodiments, a method of reducing dielectric loss of a hyperpigmented black toner is disclosed including adding a set of second colorants to a black-containing emulsion aggregation (EA) toner having an initial pigment loading of up to about 6%, up to about 5.5%, up to about 5% by weight of the toner; where the total colorant loading of the resulting toner comprising a mixture of interest is increased to greater than about 6%.
Unless otherwise indicated, all numbers expressing quantities and conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term, “about.” “About,” is meant to indicate a variation of no more than 20% from the stated value. Also used herein are the terms, “equivalent,” “similar,” “essentially,” “substantially,” “approximating” and “matching,” or grammatic variations thereof, which have generally acceptable definitions or at the least, are understood to have the same meaning as, “about.”
“Hyperpigment,” and grammatic forms thereof is meant to describe a toner or toner preparation that has a higher amount of pigment or colorant than found in conventional and/or nominal toners currently in use, which generally have a pigment or colorant content on a weight basis of no greater than about 6 wt %. A hyperpigmented toner is one with greater than 6% by weight of total amount of colorant, the increase can be at least about 10%, at least about 15%, at least about 20%, at least about 30% or more of colorant or pigment than found in conventional toners. Hyperpigmented toner preparations are also those that on printing and fusing the toner particles to the substrate to form an image of a 100% solid area single color patch, the thickness of that image is less than about 70% of a diameter of the toner particles, as provided, for example, in U.S. Pub. No. 20110250536.
In the subject matter of interest, higher pigment loading is obtained without and negative impact on toner performance, said higher pigment loading enabling use of lower amounts of toner. For example, in the case of a black toner, pigment loadings greater than 6 wt % can be used by comprising a mixture of pigments of interest, without any negative impact observed with black colorants, such as, lower charge.
As used herein, “insulative” means that a composition or molecule or polymer resists changes in the mobility of free charge.
As used herein, pH adjuster means an acid or base or buffer which may be used to change the pH of a composition (e.g., slurry, resin, aggregate, toner, and the like). Such adjusters may include, but are not limited to, sodium hydroxide (NaOH), nitric acid, sodium acetate/acetic acid, and the like.
Toner particles of interest can comprise a polyester resin. The resin comprises a polyester polymer, and in the context of a toner for use with certain imaging devices, comprises a polyester polymer that solidifies to form a particle. A composition can comprise more than one form or sort of polymer, such as, two or more different polymers, such as, two or more different polyester polymers composed of different monomers. The polymer can be an alternating copolymer, a block copolymer, a graft copolymer, a branched copolymer, a crosslinked copolymer and so on.
The toner particle can include other optional reagents, such as, a surfactant, a wax, a shell and so on. The toner composition optionally can comprise inert particles, which can serve as toner particle carriers, which can comprise the resin taught herein. The inert particles can be modified, for example, to serve a particular function. Hence, the surface thereof can be derivatized or the particles can be manufactured for a desired purpose, for example, to carry a charge or to possess a magnetic field.
A. Components
1. Resin
Toner particles of the instant disclosure include a resin forming monomer suitable for use in forming a particulate containing or carrying a colorant of a toner for use in certain imaging devices. The polymer-forming monomer is one that is inducible to form a resin, that is, which reacts, sets or solidifies to form a solid. Such a resin, a plastic, an elastomer and so on, whether naturally occurring or synthetic, is one that can be used in an imaging device. Generally, any suitable monomer or monomers are induced to polymerize to form a resin or a copolymer. Any polyfunctional monomer may be used depending on the particular polymer desired in a toner particle. Hence, bifunctional reagents, trifunctional reagents and so on can be used. One or more reagents that comprise at least three functional groups can be incorporated into a polymer or into a branch to enable branching, further branching and/or crosslinking. Certain resins, for example, can be used for applications requiring low melting temperature. Formed particles can be mixed with other reagents, such as, a colorant, to form a developer.
One, two or more polymers may be used in forming a toner or toner particle. In embodiments, where two or more polymers are used, the polymers may be in any suitable ratio (e.g., weight ratio) such as, for instance, with two different polymers, from about 1% (first polymer)/99% (second polymer) to about 99% (first polymer)/1% (second polymer), in embodiments from about 10% (first polymer)/90% (second polymer) to about 90% (first polymer)/10% (second polymer) and so on, as a design choice.
The polymer may be present in an amount of from about 65 to about 95% by weight, from about 75 to about 85% by weight of toner particles on a solids basis.
a. Polyester Resins
Suitable polyester resins include, for example, those which are sulfonated, non-sulfonated, crystalline, amorphous, combinations thereof and the like. The polyester resins may be linear, branched, crosslinked, combinations thereof and the like. Polyester resins may include those described, for example, in U.S. Pat. Nos. 6,593,049; 6,830,860; 7,754,406; 7,781,138; 7,749,672; and 6,756,176, the disclosure of each of which hereby is incorporated by reference in entirety.
When a mixture is used, such as, amorphous and crystalline polyester resins, the ratio of crystalline polyester resin to amorphous polyester resin may be in the range from about 1:99 to about 30:70; from about 5:95 to about 25:75; in embodiments, from about 5:95 to about 15:95.
A polyester resin may be obtained synthetically, for example, in an esterification reaction involving a reagent comprising a carboxylic acid group and another reagent comprising an alcohol. In embodiments, the alcohol reagent comprises two or more hydroxyl groups, in embodiments, three or more hydroxyl groups. In embodiments, the acid comprises two or more carboxylic acid groups, in embodiments, three or more carboxylic acid groups. Reagents comprising three or more functional groups enable, promote or enable and promote polymer branching and crosslinking. In embodiments, a polymer backbone or a polymer branch comprises at least one monomer unit comprising at least one pendant group or side group, that is, the monomer reactant from which the unit was obtained comprises at least three functional groups.
Examples of polyacids or polyesters that may be used for preparing an amorphous polyester resin include terephthalic acid, phthalic acid, isophthalic acid, fumaric acid, trimellitic acid, diethyl fumarate, dimethyl itaconate, cis-1,4-diacetoxy-2-butene, dimethyl fumarate, diethyl maleate, maleic acid, succinic acid, itaconic acid, succinic acid, cyclohexanoic acid, succinic anhydride, dodecylsuccinic acid, dodecylsuccinic anhydride, glutaric acid, glutaric anhydride, adipic acid, pimelic acid, suberic acid, azelaic acid, dodecanedioic acid, dimethyl naphthalenedicarboxylate, dimethyl terephthalate, diethyl terephthalate, dimethylisophthalate, diethylisophthalate, dimethylphthalate, phthalic anhydride, diethylphthalate, dimethylsuccinate, naphthalene dicarboxylic acid, dimer diacid, dimethylfumarate, dimethylmaleate, dimethylglutarate, dimethyladipate, dimethyl dodecylsuccinate, and combinations thereof. The organic polyacid or polyester reagent may be present, for example, in an amount from about 40 to about 60 mole % of the resin, in embodiments from about 42 to about 52 mole % of the resin, in embodiments from about 45 to about 50 mole % of the resin, and optionally a second polyacid can be used in an amount from about 0.1 to about 10 mole % of the resin.
Examples of polyols which may be used in generating an amorphous polyester resin include 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, bis(hydroxyethyl)-bisphenol A, bis(2-hydroxypropyl)-bisphenol A, 1,4-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, xylenedimethanol, cyclohexanediol, diethylene glycol, bis(2-hydroxyethyl) oxide, dipropylene glycol, dibutylene glycol, and combinations thereof. The amount of organic polyol may vary, and may be present, for example, in an amount from about 40 to about 60 mole % of the resin, in embodiments from about 42 to about 55 mole % of the resin, in embodiments from about 45 to about 53 mole % of the resin, and a second polyol may be used in an amount from about 0.1 to about 10 mole %, in embodiments, from about 1 to about 4 mole % of the resin.
Polycondensation catalysts may be used in forming the amorphous (or crystalline) polyester resin, and include tetraalkyl titanates, dialkyltin oxides, such as, dibutyltin oxide, tetraalkyltins, such as, dibutyltin dilaurate, and dialkyltin oxide hydroxides, such as, butyltin oxide hydroxide, aluminum alkoxides, alkyl zinc, dialkyl zinc, zinc oxide, stannous oxide, or combinations thereof. Such catalysts may be used in amounts of, for example, from about 0.01 mole % to about 5 mole % based on the starting polyacid or polyester reagent(s) used to generate the polyester resin.
Examples of amorphous resins which may be used include alkali sulfonated-polyester resins, branched alkali sulfonated-polyester resins, alkali sulfonated-polyimide resins and 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-sulfo-isophthalate), 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, a lithium or a potassium ion.
In embodiments, an unsaturated amorphous polyester resin may be used 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 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) and combinations thereof.
In embodiments, a suitable amorphous resin may include alkoxylated bisphenol A fumarate/terephthalate-based polyester and copolyester resins. In embodiments, a suitable polyester resin may be an amorphous polyester resin, such as, a poly(propoxylated bisphenol A co-fumarate) resin. Examples of such resins and processes for production thereof include those disclosed in U.S. Pat. No. 6,063,827, the disclosure of which is hereby incorporated by reference in entirety.
For forming a crystalline polyester resin, suitable organic polyols include aliphatic polyols with from about 2 to about 36 carbon atoms, such as 1,2-ethanediol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethylpropane-1,3-diol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-dodecanediol and 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, mixture thereof, and the like, including their structural isomers. The aliphatic polyol may be, for example, selected in an amount from about 40 to about 60 mole %, in embodiments from about 42 to about 55 mole %, in embodiments from about 45 to about 53 mole %, and a second polyol may be used in an amount from about 0.1 to about 10 mole %, in embodiments from about 1 to about 4 mole % of the resin.
Examples of organic polyacid or polyester reagents for preparing a crystalline resin include 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 (sometimes referred to herein, in embodiments, as cyclohexanedioic acid), malonic acid and mesaconic acid, a polyester or anhydride thereof; and an alkali sulfo-organic polyacid, such as, the sodio, lithio or potassio 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-sulfo-terephthalate, 5-sulfo-isophthalic acid, dialkyl-sulfo-terephthalate, sulfo-p-hydroxybenzoic acid, N,N-bis(2-hydroxyethyl)-2-amino ethane sulfonate, or mixtures thereof. The organic polyacid may be selected in an amount of, for example, in embodiments from about 40 to about 60 mole %, in embodiments from about 42 to about 52 mole %, in embodiments from about 45 to about 50 mole %, and optionally, a second polyacid may be selected in an amount from about 0.1 to about 10 mole % of the resin.
Specific crystalline resins include 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), copoly(2,2-dimethylpropane-1,3-diol-decanoate)-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-sulfo-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-adipatenonylene-decanoate), poly(octylene-adipate), and so on, wherein alkali is a metal like sodium, lithium or potassium. Examples of polyamides include poly(ethylene-adipamide), poly(propylene-adip amide), poly(butylenes-adipamide), poly(pentylene-adipamide), poly(hexylene-adipamide), poly(octylene-adipamide), poly(ethylene-succinimide), and poly(propylene-sebecamide). Examples of polyamides include poly(ethylene-adipimide), poly(propylene-adipimide), poly(butylene-adipimide), poly(pentylene-adipimide), poly(hexylene-adipimide), poly(octylene-adipimide), poly(ethylene-succinimide), poly(propylene-succinimide), and poly(butylene-succinimide).
Suitable crystalline resins which may be utilized, optionally in combination with an amorphous resin as described above, include those disclosed in U.S. Pub. No. 2006/0222991, the disclosure of which is hereby incorporated by reference in entirety.
In embodiments, a suitable crystalline resin may include a resin formed of ethylene glycol and a mixture of dodecanedioic acid and fumaric acid co-monomers.
The crystalline resin may be present, for example, in an amount from about 1 to about 85% by weight of the toner components, in embodiments from about 2 to about 50% by weight of the toner components, in embodiments from about 5 to about 15% 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., in embodiments from about 60° C. to about 80° C. The crystalline resin may have a number average molecular weight (Mn), 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 GPC 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.
In embodiments, to increase the gloss of the resulting toner (e.g., by about 5 gloss units) changing the ratio of at least two amorphous resins comprising the toner may be carried out. While not being bound by theory, such a ratio change may increase TMA reduction observed for a toner made by the processes as described herein.
b. Catalyst
Condensation catalysts which may be used in the polyester reaction include tetraalkyl titanates; dialkyltin oxides, such as, dibutyltin oxide; tetraalkyltins, such as, dibutyltin dilaurate; dibutyltin diacetate; dibutyltin oxide; dialkyltin oxide hydroxides, such as, butyltin oxide hydroxide; aluminum alkoxides, alkyl zinc, dialkyl zinc, zinc oxide, stannous oxide, stannous chloride, butylstannoic acid, or combinations thereof.
Such catalysts may be used in amounts of, for example, from about 0.01 mole % to about 5 mole % based on the amount of starting polyacid, polyol or polyester reagent in the reaction mixture.
Generally, as known in the art, the polyacid/polyester and polyols reagents are mixed together, optionally with a catalyst, and incubated at an elevated temperature, such as, from about 180° C. or more, from about 190° C. or more, from about 200° C. or more, and so on, which can be conducted anaerobically, to enable esterification to occur until equilibrium, which generally yields water or an alcohol, such as, methanol, arising from forming the ester bonds in esterification reactions. The reaction may be conducted under vacuum to promote polymerization. The product is collected by practicing known methods, and may be dried, again, by practicing known methods to yield particulates.
Branching agents may be used, and include, for example, a multivalent polyacid such as 1,2,4-benzene-tricarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 2,5,7-naphthalenetricarboxylic acid, 1,2,4-naphthalenetricarboxylic acid, 1,2,5-hexanetricarboxylic acid, 1,3-dicarboxyl-2-methyl-2-methylene-carboxylpropane, tetra(methylene-carboxyl)methane, 1,2,7,8-octanetetracarboxylic acid, acid anhydrides thereof, lower alkyl esters thereof and so on. The branching agent may be used in an amount from about 0.01 to about 10 mole % of the resin, from about 0.05 to about 8 mole % or from about 0.1 to about 5 mole % of the resin.
It may be desirable to crosslink the polymer. A suitable resin conducive to crosslinking is one with a reactive group, such as, a C═C bond or with pendant or side groups, such as, a carboxylic acid group. The resin may be crosslinked, for example, through free radical polymerization with an initiator. Suitable initiators include peroxides such as, organic peroxides or azo compounds, for example diacyl peroxides, such as, decanoyl peroxide, lauroyl peroxide and benzoyl peroxide, ketone peroxides, such as, cyclohexanone peroxide and methyl ethyl ketone, alkyl peroxy esters, such as, t-butyl peroxy neodecanoate, 2,5-dimethyl 2,5-di(2-ethyl hexanoyl peroxy)hexane, tamyl peroxy 2-ethyl hexanoate, t-butyl peroxy 2-ethyl hexanoate, t-butyl peroxy acetate, t-amyl peroxy acetate, t-butyl peroxy benzoate, t-amyl peroxy benzoate, alkyl peroxides, such as, dicumyl peroxide, 2,5-dimethyl 2,5-di(t-butyl peroxy)hexane, t-butyl cumyl peroxide, bis(t-butyl peroxy)diisopropyl benzene, di-t-butyl peroxide and 2,5-dimethyl 2,5-di(t-butyl peroxy)hexyne-3, alkyl hydroperoxides, such as, 2,5-dihydro peroxy 2,5-dimethyl hexane, cumene hydroperoxide, t-butyl hydroperoxide and t-amyl hydroperoxide, and alkyl peroxyketals, such as, n-butyl 4,4-di(t-butyl peroxy)valerate, 1,1-di(t-butyl peroxy) 3,3,5-trimethyl cyclohexane, 1,1-di(t-butyl peroxy)cyclohexane, 1,1-di(t-amyl peroxy)cyclohexane, 2,2-di(t-butyl peroxy)butane, ethyl 3,3-di(t-butyl peroxy)butyrate and ethyl 3,3-di(t-amyl peroxy)butyrate, azobis-isobutyronitrile, 2,2′-azobis(isobutyronitrile), 2,2′-azobis(2,4-dimethyl valeronitrile), 2,2′-azobis(methyl butyronitrile), 1,1′-azobis(cyano cyclohexane), 1,1-di(t-butyl peroxy)-3,3,5-trimethylcyclohexane, combinations thereof and the like. The amount of initiator used is proportional to the degree of crosslinking, and thus, the gel content of the polyester material. The amount of initiator used may range from, for example, about 0.01 to about 10 weight %, or from about 0.1 to about 5 weight % of the polyester resin. In the crosslinking, it is desirable that substantially all of the initiator be consumed. The crosslinking may be carried out at high temperature, and thus the reaction may be very fast, for example, less than 10 minutes, such as from about 20 seconds to about 2 minutes residence time.
The polymer reagent then may be incorporated with, for example, other reagents suitable for making a toner particle, such as, a colorant and/or a wax, and processed in a known manner to produce toner particles.
c. Other Resins
Examples of other suitable resins or polymers which may be utilized in forming a toner include, but are not limited to, styrenes, acrylates, acrylic acids, butadienes and so on, as known in the art, including combinations thereof, such as, 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-acrylic acid), poly(styrene-butadiene-methacrylic acid), poly(styrene-butadiene-acrylonitrile-acrylic acid), poly(styrene-butyl acrylate-acrylic acid), poly(styrene-butyl acrylate-methacrylic acid), poly(styrene-butyl acrylate-acrylonitrile), poly(styrene-butyl acrylate-acrylonitrile-acrylic acid), and combinations thereof. The polymer may be, for example, block, random, or alternating copolymers.
2. Colorants
Pigment Selection
In embodiments, nominally pigmented black toner can contain about 6% black colorant, such as, Nipex 35. At that loading, charge, dielectric loss, transfer and image quality (IQ) are excellent. While not to be bound by theory, one way to maintain performance with the intent to enable lower TMA with 45% higher hyperpigmentation may be to replace the additional Nipex 35 carbon black with a set of two or more colorants or pigments, which generally are of a color other than black but one or more of the mixture can be a black colorant. Advantageously, the second, additional set of colorants, in the context above, optionally, other than a black colorant, are insulative. Thus, dielectric loss would not increase and performance would remain unaffected. Pigments selected need not only be insulative, but can exhibit a spectral response that is substantially the same as that of the primary or first colorant, in the context of the above example, black. In embodiments, the selection is based on spectral response curves. Hence, the dielectric loss of a toner of interest can be less than about 40×10−3, less than about 35×10−3, less than about 30×10−3.
Suitable colorants include those comprising carbon black, such as, REGAL 330® and Nipex 35; magnetites, such as, Mobay magnetites, MO8029™ and MO8060™; Columbian magnetites, MAPICO® BLACK; surface-treated magnetites; Pfizer magnetites, CB4799™, CB5300™, CB5600™ and MCX6369™; Bayer magnetites, BAYFERROX 8600™ and 8610 ™; Northern Pigments magnetites, NP604™ and NP608™; Magnox magnetites, TMB-100™ or TMB104™; and the like.
Colored pigments, such as cyan, magenta, orange, violet, brown, blue or mixtures thereof can be used, where the colored pigments exhibit a spectral response reflectance of R=0.20 or lower over the full spectral range, from about 400 to about 700 nm. The additional pigment or pigments may be used as waterbased pigment dispersions.
Examples of pigments include SUNSPERSE 6000, FLEXIVERSE and AQUATONE, water-based pigment dispersions from SUN Chemicals; HELIOGEN BLUE L6900™, D6840™, D7080™, D7020™, PYLAM OIL BLUE™, and PIGMENT BLUE I™ available from Paul Uhlich & Company, Inc.; PIGMENT VIOLET I™ available from Dominion Color Corporation, Ltd., and the like.
Illustrative examples of cyan pigments include copper tetra(octadecylsulfonamido) phthalocyanine, a copper phthalocyanine pigment listed in the Color Index as CI 74160, CI Pigment Blue, Pigment Blue 15:3, Pigment Blue 15:4, an Anthrazine Blue identified in the Color Index as CI 69810, Special Blue X-2137 and the like.
Other known colorants may be used, such as, Levanyl Black ASF (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 B2G 01 (American Hoechst), Sunsperse Blue BM 6000 (Sun Chemicals), Irgalite Blue BCA (CibaGeigy), Paliogen Blue 6470 (BASF), Sudan Orange G (Aldrich), Sudan Orange 220 (BASF), Paliogen Orange 3040 (BASF), Ortho Orange OR 2673 (Paul Uhlich) combinations of the foregoing and the like. Other pigments that may be used, and which are commercially available include various pigments in the color classes, including, but not limited to Pigment Violet 23 and Pigment Violet 3.
The colorant, for example furnace carbon black, cyan, violet and/or orange colorant, may be incorporated in an amount sufficient to impart the desired reduction in dielectric loss. In general, pigment, may be employed in an amount greater than 6%, such as, ranging from about 7% to about 17% by weight of the toner particles on a solids basis, from about 8% to about 15% by weight or from about 9% to about 13% by weight.
In embodiments, portions of the pigment loading, for example furnace carbon black (e.g., but not limited to, Nipex 35), may be replaced by two or more second colorants or pigments that are not blacks. In certain embodiments, the pigment loading is increased by at least about 10%, by at least about 20%, by at least about 30% or more by replacing portions of the black with a set of color pigments that are insulative, where such insulative pigments exhibit a spectral response that is substantially the same as carbon black (CB), and where such color pigments may be selected based on spectral response curve data. In embodiments, nominal black (K) toner at 7% wt pigment comprising about 6% Nipex 35 (CB) and about 1% Pigment Blue (PB) 15.3, provides a spectral response reflectance of R=0.02 from about 400 to about 700 nm when printed at a TMA of about 0.45 mg/cm2. In embodiments, low TMA K toner at 10.15% pigment loading may comprise about 6% Nipex 35 (CB), 1% PB 15.3 and then by adding an additional 2.7% Nipex 35, and 0.45% PB 15.3 and provides a spectral response reflectance of R=0.02 from about 400 to about 700 nm, at a lower TMA of about 0.31 mg/cm2. Thus, the increased pigment allows use of less toner on the print. In embodiments, a toner comprising 10% Pigment Orange (PO) 34 provides a spectral response reflectance of R=0.02 from about 400 to about 530. In embodiments, a toner with a reflex blue color comprising 7.2% PB 15.3 and 1.8% Pigment Violet (PV) 23 provides a spectral response reflectance R=0.02 from about 530 to about 700 nm at nominal toner TMA. Again, while not being bound by theory, calculating proportions for a hyperpigmented formulation, the following may be added to the nominal K formulation: about 4.5% PO 34, about 3.2% PB 15.3, and 0.81% PV 23 to allow for the low reflectance of R=0.02 or lower over the full spectral response range. Based on those calculations, for example, 2.7% CB added to nominal K toner to make a hyperpigmented black may be replaced by 7.7% of extra color pigments. In embodiments, a hyperpigmented formulation as disclosed is increased in total pigment loading from about 10.15 to about 15.61%, and may comprise about 6% Nipex 35, 4.2% PB 15.3, 4.5% PO, and 0.81% PV 23.
In embodiments, at least three colorants are present in a toner particle. For example, three colorants may be present in a toner particle, such as, a first colorant of pigment blue, may be present in an amount ranging from about 1% to about 10% by weight of the toner particle on a solids basis, from about 2% to about 8% by weight or from about 3% to about 4.2% by weight; with a second colorant of pigment orange that may be present in an amount ranging from about 1% to about 10% by weight of the toner particle on a solids basis, from about 2% to about 8% by weight or from about 3% to about 4.5% by weight with a third colorant of pigment violet that may be present in an amount ranging from about 0% to about 0.81% by weight of the toner particle on a solids basis, from about 0.1% to about 1.0% by weight or from about 0.5% to about 0.7% by weight and so on.
In embodiments, pigments can be added such that one pigment adsorbs at least over the range of about 400 nm to about 540 nm, a second pigment adsorbs at least over the range of about 540 to 600 nm, a third pigment adsorbs at least over a range of about 600 to 700 nm, and optionally a black pigment that adsorbs at least over a range of about 400 nm to about 700 nm. One of the two or more pigments of the mixture of interest can be a black colorant.
3. Optional Components
a. Surfactants
In embodiments, toner compositions, colorants and so on may be in dispersions including surfactants. Emulsion aggregation methods where the polymer and other components of the toner are in combination may employ one or more surfactants to form an emulsion.
One, two or more surfactants may be used. The surfactants may be selected from ionic surfactants and nonionic surfactants, or combinations thereof. Anionic surfactants and cationic surfactants are encompassed by the term, “ionic surfactants.”
In embodiments, the surfactant or the total amount of surfactants may be used in an amount of from about 0.01% to about 5% by weight of the toner forming composition, for example, from about 0.75% to about 4% by weight of the toner-forming composition, in embodiments, from about 1% to about 3% by weight of the toner-forming composition.
Examples of nonionic surfactants include, for example, polyoxyethylene cetyl ether, polyoxyethylene lauryl ether, polyoxyethylene octyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene oleyl ether, polyoxyethylene sorbitan monolaurate, polyoxyethylene stearyl ether, polyoxyethylene nonylphenyl ether and dialkylphenoxy poly(ethyleneoxy) ethanol, for example, available from Rhone-Poulenc as IGEPAL CA210™, IGEPAL CA520™, 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 a block copolymer of polyethylene oxide and polypropylene oxide, including those commercially available as SYNPERONIC® PR/F, in embodiments, SYNPERONIC® PR/F 108; and a DOWFAX, available from The Dow Chemical Corp.
Anionic surfactants include sulfates and sulfonates, such as, sodium dodecylsulfate (SDS), sodium dodecylbenzene sulfonate, sodium dodecylnaphthalene sulfate and so on; dialkyl benzenealkyl sulfates; acids, such as, palmitic acid, and NEOGEN or NEOGEN SC obtained from Daiichi Kogyo Seiyaku, and so on, combinations thereof and the like. Other suitable anionic surfactants include, in embodiments, alkyldiphenyloxide disulfonates or TAYCA POWER BN2060 from Tayca Corporation (Japan), which is a branched sodium dodecyl benzene sulfonate. Combinations of those surfactants and any of the foregoing nonionic surfactants may be used in embodiments.
Examples of cationic surfactants include, for example, alkylbenzyl dimethyl ammonium chloride, dialkyl benzenealkyl ammonium chloride, lauryl trimethyl ammonium chloride, alkylbenzyl methyl ammonium chloride, alkyl benzyl dimethyl ammonium bromide, benzalkonium chloride, cetyl pyridinium bromide, trimethyl ammonium bromides, halide salts of quarternized polyoxyethylalkylamines, dodecylbenzyl triethyl ammonium chlorides, MIRAPOL® and ALKAQUAT® available from Alkaril Chemical Company, SANISOL® (benzalkonium chloride) available from Kao Chemicals and the like, and mixtures thereof, including, for example, a nonionic surfactant as known in the art or provided hereinabove.
b. Waxes
The toners of the instant disclosure, optionally, may contain a wax, which can be either a single type of wax or a mixture of two or more different types of waxes (hereinafter identified as, “a wax”). A wax can be added to a toner formulation or to a developer formulation, for example, to improve particular toner properties, such as, toner particle shape, charging, fusing characteristics, gloss, stripping, offset properties and the like. Alternatively, a combination of waxes can be added to provide multiple properties to a toner or a developer composition. A wax may be included as, for example, a fuser roll release agent.
The wax may be combined with the resin-forming composition for forming toner particles. 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, those that are commercially available, for example, POLYWAX™ polyethylene waxes from Baker Petrolite, wax emulsions available from Michaelman, Inc. or Daniels Products Co., EPOLENE N15™ which is commercially available from Eastman Chemical Products, Inc., VISCOL 550P™, a low weight average molecular weight polypropylene available from Sanyo Kasei K.K.; plant-based waxes, such as carnauba wax, rice wax, candelilla wax, sumac wax and jojoba oil; animal-based waxes, such as beeswax; mineral-based waxes and petroleum-based waxes, such as montan wax, ozokerite, ceresin wax, paraffin wax, microcrystalline wax and FischerTropsch waxes; ester waxes obtained from higher fatty acids and higher alcohols, such as stearyl stearate and behenyl behenate; ester waxes obtained from higher fatty acids and monovalent or multivalent lower alcohols, such as butyl stearate, propyl oleate, glyceride monostearate, glyceride distearate and pentaerythritol tetrabehenate; ester waxes obtained from higher fatty acids 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; cholesterol higher fatty acid ester waxes, such as, cholesteryl stearate, and so on.
Examples of functionalized waxes that may be used include, for example, amines and 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™ also available from Micro Powder Inc.; imides, esters, quaternary amines, carboxylic acids, acrylic polymer emulsions, for example, JONCRYL 74™, 89™, 130™, 537™ and 538™ available from SC Johnson Wax; and chlorinated polypropylenes and polyethylenes available from Allied Chemical, Petrolite Corp. and SC Johnson. Mixtures and combinations of the foregoing waxes also may be used in embodiments.
c. Aggregating Factor
An aggregating factor may be an inorganic cationic coagulant, such as, for example, polyaluminum chloride (PAC), polyaluminum sulfosilicate (PASS), aluminum sulfate, zinc sulfate, magnesium sulfate, chlorides of magnesium, calcium, zinc, beryllium, aluminum, sodium, other metal halides including monovalent and divalent halides.
The aggregating factor may be present in an emulsion in an amount of from, for example, from about 0.01 to about 10 wt %, or from about 0.05 to about 5 wt % based on the total solids in the toner.
The aggregating factor may also contain minor amounts of other components, for example, nitric acid.
In embodiments, a sequestering agent or chelating agent may be introduced after aggregation is complete to sequester or extract a metal complexing ion, such as, aluminum from the aggregation process. Thus, the sequestering, chelating or complexing agent used after aggregation is complete may comprise an organic complexing component, such as, ethylenediaminetetraacetic acid (EDTA), gluconal, hydroxyl-2,2′iminodisuccinic acid (HIDS), dicarboxylmethyl glutamic acid (GLDA), methyl glycidyl diacetic acid (MGDA), hydroxydiethyliminodiacetic acid (HIDA), sodium gluconate, potassium citrate, sodium citrate, nitrotriacetate salt, humic acid, fulvic acid; salts of EDTA, such as, alkali metal salts of EDTA, tartaric acid, gluconic acid, oxalic acid, polyacrylates, sugar acrylates, citric acid, polyasparic acid, diethylenetriamine pentaacetate, 3-hydroxy-4-pyridinone, dopamine, eucalyptus, iminodisuccinic acid, ethylenediaminedisuccinate, polysaccharide, sodium ethylenedinitrilotetraacetate, thiamine pyrophosphate, farnesyl pyrophosphate, 2-aminoethylpyrophosphate, hydroxyl ethylidene-1,1-diphosphonic acid, aminotrimethylenephosphonic acid, diethylene triaminepentamethylene phosphonic acid, ethylenediamine tetramethylene phosphonic acid, and mixtures thereof.
d. Surface Additives
In embodiments, the toner particles may be mixed with one or more of silicon dioxide or silica (SiO2), titania or titanium dioxide (TiO2) and/or cerium oxide. Silica may be a first silica and a second silica. The first silica may have an average primary particle size, measured in diameter, in the range of, for example, from about 5 nm to about 50 nm, such as, from about 5 nm to about 25 nm or from about 20 nm to about 40 nm. The second silica may have an average primary particle size, measured in diameter, in the range of, for example, from about 100 nm to about 200 nm, such as, from about 100 nm to about 150 nm or from about 125 nm to about 145 nm. The second silica may have a larger average size (diameter) than the first silica. The titania may have an average primary particle size in the range of, for example, about 5 nm to about 50 nm, such as, from about 5 nm to about 20 nm or from about 10 nm to about 50 nm. The cerium oxide may have an average primary particle size in the range of, for example, about 5 nm to about 50 nm, such as, from about 5 nm to about 20 nm or from about 10 nm to about 50 nm.
Zinc stearate also may be used as an external additive. Calcium stearate and magnesium stearate may provide similar functions. Zinc stearate may have an average primary particle size in the range of, for example, from about 500 nm to about 700 nm, such as, from about 500 nm to about 600 nm or from about 550 nm to about 650 nm.
e. Carrier
Carrier particles include those that are capable of triboelectrically obtaining a charge of polarity opposite to that of the toner particles. Illustrative examples of suitable carrier particles include granular zircon, granular silicon, glass, steel, nickel, ferrites, iron ferrites, silicon dioxide, nickel berry carriers as disclosed in U.S. Pat. No. 3,847,604, the entire disclosure of which is hereby incorporated herein by reference, comprised of nodular carrier beads of nickel, characterized by surfaces of reoccurring recesses and protrusions thereby providing particles with a relatively large external area, those disclosed in U.S. Pat. Nos. 4,937,166 and 4,935,326, the disclosure of each of which hereby is incorporated herein by reference, and so on. In embodiments, the carrier particles may have an average particle size of, for example, from about 20 to about 85 μm, such as, from about 30 to about 60 μm, or from about 35 to about 50 μm.
B. Toner Particle Preparation
1. Method
a. Particle Formation
The toner particles may be prepared by any method within the purview of one skilled in the art, for example, any of the emulsion/aggregation methods may be used with a polyester resin and the first and second colorants as taught herein. Any suitable method of preparing toner particles may be used, including chemical processes, such as, suspension and encapsulation processes disclosed, for example, 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; by conventional granulation methods, such as, jet milling; pelletizing slabs of material; other mechanical processes; any process for producing nanoparticles or microparticles; and so on.
In embodiments relating to an emulsification/aggregation process, a resin may be dissolved in a solvent, and may be mixed into an emulsion medium, for example water, such as, deionized water, optionally containing a stabilizer, and optionally a surfactant. Examples of suitable stabilizers include water-soluble alkali metal hydroxides, such as, sodium hydroxide, potassium hydroxide, lithium hydroxide, beryllium hydroxide, magnesium hydroxide, calcium hydroxide or barium hydroxide; ammonium hydroxide; alkali metal carbonates, such as, sodium bicarbonate, lithium bicarbonate, potassium bicarbonate, lithium carbonate, potassium carbonate, sodium carbonate, beryllium carbonate, magnesium carbonate, calcium carbonate, barium carbonate or cesium carbonate; or mixtures thereof. When a stabilizer is used, the stabilizer may be present in amounts of from about 0.1% to about 5%, from about 0.5% to about 3% by weight of the resin. When such salts are added to the composition as a stabilizer, in embodiments, incompatible metal salts are not present in the composition, for example, a composition may be completely or essentially free of zinc and other incompatible metal ions, for example, Ca, Fe, Ba etc., that form water-insoluble salts. The term, “essentially free,” refers, for example, to the incompatible metal ions as present at a level of less than about 0.01%, less than about 0.005% or less than about 0.001%, by weight of the wax and resin. The stabilizer may be added to the mixture at ambient temperature, or may be heated to the mixture temperature prior to addition.
Optionally, a surfactant may be added to the aqueous emulsion medium, for example, to afford additional stabilization to the resin or to enhance emulsification of the resin. Suitable surfactants include anionic, cationic and nonionic surfactants as taught herein.
Following emulsification, toner compositions may be prepared by aggregating a mixture of a resin, the first and second colorants of interest, an optional wax and any other desired additives in an emulsion, optionally, with surfactants as described above, and then optionally coalescing the aggregate mixture. A mixture may be prepared by adding an optional wax or other materials, which may also be optionally in a dispersion, including a surfactant, to the emulsion comprising a resin-forming material and the first and second colorants, which may be a mixture of two or more emulsions containing the requisite reagents. The pH of the resulting mixture may be adjusted with an acid, 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, mixing may be at from about 600 to about 4,000 rpm. Homogenization may be by any suitable means, including, for example, an IKA ULTRA TURRAX T50 probe homogenizer.
b. Aggregation
Following preparation of the above mixture, often, it is desirable to form larger particles or aggregates, often sized in micrometers, of the smaller particles from the initial polymerization reaction, often sized in nanometers. An aggregating factor may be added to the mixture. Suitable aggregating factors include, for example, aqueous solutions of a divalent cation, a multivalent cation or a compound comprising same.
The aggregating factor, as provided above, may be, for example, a polyaluminum halide, such as, polyaluminum chloride (PAC) or the corresponding bromide, fluoride or iodide; a polyaluminum silicate, such as, polyaluminum sulfosilicate (PASS); or a water soluble metal salt, 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 combinations thereof.
In embodiments, the aggregating factor may be added to the mixture at a temperature that is below the glass transition temperature (Tg) of the resin or of a polymer.
The aggregating factor may be added to the mixture components to form a toner in an amount of, for example, from about 0.1 part per hundred (pph) to about 1 pph, in embodiments, from about 0.25 pph to about 0.75 pph, in embodiments, about 0.5 pph of the reaction mixture.
To control aggregation of the particles, the aggregating factor may be metered into the mixture over time. For example, the factor may be added incrementally into the mixture over a period of from about 5 to about 240 minutes, in embodiments, from about 30 to about 200 minutes.
Addition of the aggregating factor also may 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 or polymer, in embodiments, from about 30° C. to about 90° C., in embodiments, from about 35° C. to about 70° C. The growth and shaping of the particles following addition of the aggregation factor may be accomplished under any suitable condition(s).
The particles may be permitted to aggregate until a predetermined desired particle size is obtained. Particle size may be monitored during the growth process. For example, 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 mixture, for example, at elevated temperature, or slowly raising the temperature, for example, from about 40° C. to about 100° C., and holding the mixture at that temperature for from about 0.5 hours to about 6 hours, in embodiments, from about hour 1 to about 5 hours, while maintaining stirring, to provide the desired aggregated particles. Once the predetermined desired particle size is attained, the growth process is halted.
The characteristics of the toner particles may be determined by any suitable technique and apparatus. Volume average particle diameter and geometric standard deviation may be measured using an instrument, such as, a Beckman Coulter MULTISIZER 3, operated in accordance with the instructions of the manufacturer. Representative sampling may occur by taking a sample, filtering through a 25 μm membrane, diluting in an isotonic solution to obtain a concentration of about 10% and then reading the sample, for example, in a Beckman Coulter MULTISIZER 3.
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, of 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 or a polymer.
In embodiments, the aggregate particles may be of a size of less than about 3 μm, in embodiments from about 2 μm to about 3 μm, in embodiments from about 2.5 μm to about 2.9 μm.
In embodiments, after aggregation, but prior to coalescence, a resin coating may be applied to the aggregated particles to form a shell thereover. Any resin described herein or as known in the art may be used as the shell. In embodiments, a polyester amorphous resin latex as described herein may be included in the shell. In embodiments, a polyester amorphous resin latex described herein may be combined with a different resin, and then added to the particles as a resin coating to form a shell.
A shell resin may be applied to the aggregated particles by any method within the purview of those skilled in the art. In embodiments, the resins used to form the shell may be in an emulsion, optionally including any surfactant described herein. The emulsion possessing the resins may be combined with the aggregated particles so that the shell forms over the aggregated particles.
The formation of the shell over the aggregated particles may occur while heating to a temperature from about 30° C. to about 80° C., in embodiments from about 35° C. to about 70° C. The formation of the shell may take place for a period of time from about 5 minutes to about 10 hours, in embodiments from about 10 minutes to about 5 hours.
The shell may be present in an amount from about 1% by weight to about 80% by weight of the toner components, in embodiments from about 10% by weight to about 40% by weight of the toner components, in embodiments from about 20% by weight to about 35% by weight of the toner components.
c. Coalescence
Following aggregation to a desired particle size and application of any optional shell, the particles then may be coalesced to a desired final shape, such as, a circular shape, for example, to correct for irregularities in shape and size, the coalescence being achieved by, for example, heating the mixture to a temperature from about 45° C. to about 100° C., in embodiments from about 55° C. to about 99° C., which may be at or above the Tg of the resins used to form the toner particles, and/or reducing the stirring, for example to from about 1000 rpm to about 100 rpm, in embodiments from about 800 rpm to about 200 rpm. Coalescence may be conducted over a period from about 0.01 to about 9 hours, in embodiments from about 0.1 to about 4 hours, see, for example, U.S. Pat. No. 7,736,831.
After aggregation and/or 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 by any suitable method, including, for example, freeze-drying.
Optionally, a coalescing agent may be used. Examples of suitable coalescence agents include, but are not limited to, benzoic acid alkyl esters, ester alcohols, glycol/ether-type solvents, long chain aliphatic alcohols, aromatic alcohols, mixtures thereof and the like. Examples of benzoic acid alkyl esters include those where the alkyl group, which may be straight or branched, substituted or unsubstituted, has from about 2 to about 30 carbon atoms, such as decyl or isodecyl benzoate, nonyl or isononyl benzoate, octyl or isooctyl benzoate, 2-ethylhexyl benzoate, tridecyl or isotridecyl benzoate, 3,7-dimethyloctyl benzoate, 3,5,5-trimethylhexyl benzoate, mixtures thereof and the like. Examples of such benzoic acid alkyl esters include VELTA® 262 (isodecyl benzoate) and VELTA® 368 (2-ethylhexyl benzoate) available from Velsicol Chemical Corp. Examples of ester alcohols include hydroxyalkyl esters of alkanoic acids, where the alkyl group, which may be straight or branched, substituted or unsubstituted, and may have from about 2 to about 30 carbon atoms, such as, 2,2,4-trimethylpentane-1,3-diol monoisobutyrate. An example of an ester alcohol is TEXANOL® (2,2,4-trimethylpentane-1,3-diol monoisobutyrate) available from Eastman Chemical Co. Examples of glycol/ether-type solvents include diethylene glycol monomethylether acetate, diethylene glycol monobutylether acetate, butyl carbitol acetate (BCA) and the like. Examples of long chain aliphatic alcohols include those where the alkyl group is from about 5 to about 20 carbon atoms, such as, ethylhexanol, octanol, dodecanol and the like. Examples of aromatic alcohols include benzyl alcohol and the like.
In embodiments, the coalescence agent (or coalescing agent or coalescence aid agent) evaporates during later stages of the emulsion/aggregation process, such as, during a second heating step, that is, generally above the Tg of the resin or a polymer. The final toner particles are thus, free of, or essentially or substantially free of any remaining coalescence agent. To the extent that any remaining coalescence agent may be present in a final toner particle, the amount of remaining coalescence agent is such that presence thereof does not affect any properties or the performance of the toner or developer.
The coalescence agent can be added prior to the coalescence or fusing step in any desired or suitable amount. For example, the coalescence agent may be added in an amount of from about 0.01 to about 10% by weight, based on the solids content in the reaction medium, or from about 0.05, or from about 0.1%, to about 0.5 or to about 3.0% by weight, based on the solids content in the reaction medium. Of course, amounts outside those ranges can be used, as desired.
In embodiments, the coalescence agent can be added at any time between aggregation and coalescence, although in some embodiments it may be desirable to add the coalescence agent after aggregation is, “frozen,” or completed, for example, by adjustment of pH, for example, by addition, for example, of base.
Coalescence may proceed and be accomplished over a period of from about 0.1 to about 9 hours, in embodiments, from about 0.5 to about 4 hours.
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 in 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 drying including, for example, freeze drying.
d. Shells
In embodiments, an optional shell may be applied to the formed toner particles, aggregates or coalesced particles. Any polymer, including those described above as suitable for the core, may be used for the shell. The shell polymer may be applied to the particles or aggregates by any method within the purview of those skilled in the art.
In embodiments, an amorphous polyester resin may be used to form a shell over the particles or aggregates to form toner particles or aggregates having a core/shell configuration. In some embodiments, a low molecular weight amorphous polyester resin may be used to form a shell over the particles or aggregates.
The shell polymer may be present in an amount of from about 10% to about 32% by weight of the toner particles or aggregates, in embodiments, from about 24% to about 30% by weight of the toner particles or aggregates.
Once the desired final size of the toner particles or aggregates is achieved, the pH of the mixture may be adjusted with base to a value of from about 6 to about 10, in embodiments, from about 6.2 to about 7. The adjustment of pH may be used to freeze, that is, to stop, toner particle growth. The base used to stop toner particle growth may be, for example, an alkali metal hydroxide, such as, for example, sodium hydroxide, potassium hydroxide, ammonium hydroxide, combinations thereof and the like. In embodiments, EDTA may be added to assist adjusting the pH to the desired value.
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. Following aggregation to the desired particle size, with the formation of an optional shell as described above, the particles then may be coalesced to the desired final shape, the coalescence being 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., in embodiments, about 70° C., which may be below the melting point of the resin or polymer(s) to prevent plasticization. Higher or lower temperatures may be used, it being understood that the temperature is a function of the polymer(s) used for the core and/or shell.
e. Optional Additives
In embodiments, the toner particles also may contain other optional additives.
i. Charge Additives
The toner may include any known charge additives in amounts of from about 0.1 to about 10 weight %, in embodiments, of from about 0.5 to about 7 weight % of the toner. Examples of such charge additives include alkyl pyridinium halides, bisulfates, the charge control additives of U.S. Pat. Nos. 3,944,493; 4,007,293; 4,079,014; 4,394,430; and 4,560,635, the disclosure of each of which hereby is incorporated by reference in entirety, negative charge enhancing additives, such as, aluminum complexes, and the like.
Charge enhancing molecules can be used to impart either a positive or a negative charge on a toner particle. Examples include quaternary ammonium compounds, see, for example, U.S. Pat. No. 4,298,672, organic sulfate and sulfonate compounds, see for example, U.S. Pat. No. 4,338,390, cetyl pyridinium tetrafluoroborates, distearyl dimethyl ammonium methyl sulfate, aluminum salts and so on.
Such enhancing molecules may be present in an amount of from about 0.1 to about 10% or from about 1 to about 3% by weight.
ii. Surface Modifications
Surface additives may be added to the toner compositions of the present disclosure, for example, after washing or drying. Examples of such surface additives include, for example, one or more of a metal salt, a metal salt of a fatty acid, a colloidal silica, a metal oxide, such as, TiO2 (for example, for improved RH stability, tribo control and improved development and transfer stability), an aluminum oxide, a cerium oxide, a strontium titanate, SiO2, mixtures thereof and the like. Examples of such additives include those disclosed in U.S. Pat. Nos. 3,590,000; 3,720,617; 3,655,374; and 3,983,045, the disclosure of each of which hereby is incorporated by reference in entirety.
Surface additives may be used in an amount of from about 0.1 to about 10 wt %, or from about 0.5 to about 7 wt % of the toner.
Other surface additives include lubricants, such as, a metal salt of a fatty acid (e.g., zinc or calcium stearate) or long chain alcohols, such as, UNILIN 700 available from Baker Petrolite and AEROSIL R972® available from Degussa. The coated silicas of U.S. Pat. Nos. 6,190,815 and 6,004,714, the disclosures of each of which hereby are incorporated by reference in entirety, also can be present. The additive can be present in an amount of from about 0.05 to about 5%, and in embodiments, of from about 0.1 to about 2% of the toner, which additives can be added during the aggregation or blended into the formed toner product.
Silica, for example, may enhance toner flow, tribo control, admix control, improved development and transfer stability and higher toner blocking temperature. Zinc, calcium or magnesium stearate also may provide developer conductivity, tribo enhancement, higher toner charge and charge stability. The external surface additives may be used with or without a coating or shell.
The gloss of a toner may be influenced by the amount of retained metal ion, such as, Al3+, in a particle. The amount of retained metal ion may be adjusted further by the addition of a chelator, such as, EDTA. In embodiments, the amount of retained catalyst, 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, in embodiments, about 0.5 pph. The gloss level of a toner of the instant disclosure may have a gloss, as measured by Gardner gloss units (gu), of from about 20 gu to about 100 gu, in embodiments, from about 50 gu to about 95 gu, in embodiments, from about 60 gu to about 90 gu.
Hence, a particle can contain at the surface one or more silicas, one or more metal oxides, such as, a titanium oxide and a cerium oxide, a lubricant, such as, a zinc stearate and so on. In some embodiments, a particle surface may comprise two silicas, two metal oxides, such as, titanium oxide and cerium oxide, and a lubricant, such as, a zinc stearate. All of those surface components may comprise about 5% by weight of a toner particle weight. There may also be blended with the toner compositions, external additive particles including flow aid additives, which additives may be present on the surface of the toner particles. Examples of these additives include metal oxides like titanium oxide, tin oxide, mixtures thereof, and the like; colloidal silicas, such as AEROSIL®, metal salts and metal salts of fatty acids, including zinc stearate, aluminum oxides, cerium oxides, and mixtures thereof. Each of the external additives may be present in embodiments in amounts of from about 0.1 to about 5 wt %, or from about 0.1 to about 1 wt %, of the toner. Several of the aforementioned additives are illustrated in U.S. Pat. Nos. 3,590,000, 3,800,588, and 6,214,507, the disclosure of which is incorporated herein by reference.
A desirable characteristic of a toner is sufficient release of the paper image from the fuser roll. For oil-containing fuser rolls, the toner may not contain a wax. However, for fusers without oil on the fuser (usually hard rolls), the toner will usually contain a lubricant like a wax to provide release and stripping properties. Thus, a toner characteristic for contact fusing applications is that the fusing latitude, that is, the temperature difference between the minimum fixing temperature (MFT) and the hot offset temperature, should be from about 50° C. to about 100° C., from about 75° C. to about 100° C., from about 80° C. to about 100° C. and from about 90° C. to about 95° C.
For the evaluation of toner particles, for example, in the examples that follow, the parent charge can be measured by conditioning the toner at a specific TC (Toner Concentration, e.g., 8%) with standard 35 μm Xerox DocuColor 2240 carrier, in both the A-zone and the C-zone overnight, followed by charge evaluation after either 2 minutes or 60 minutes of mixing on a Turbula mixer. Humidity sensitivity is an important charging property for EA toners. The charging performance was tested in two environmental chambers, one is a low-humidity zone (also known as the C-zone), while another is a high humidity zone (also known as the A-zone). The quantity of charge is a value measured through image analysis of the charge-spectrograph process (CSG). Toner charge-to-diameter ratios (q/d) in the C- and A-zones, typically with a unit of femtocoulombs/(mm), can be measured on a known standard charge spectrograph. Furthermore, the tribo blow-off Q/m values in μC/g may also be measured using a blow-off method with a Barbetta Box. A prescribed amount of toner is blended with the carrier. The blending is performed by the paint shaker in four (4) ounce glass jars or may be performed in a Turbula. The blending of the toner and carrier components results in an interaction, where toner particles become negatively charged and carrier particles become positively charged. Samples of the resulting mixture are loaded into a Robot Cage and weighed. Via instrument air and a vacuum source, the toner is removed from the carrier, while the carrier is retained by the screened Robot Cage. The residual charge on the carrier is detected by an electrometer in Coulombs (relating to Tribo). The residual charge and the weight of toner blown off may be used to calculate the Tribo. Using the weights of toner blown off and retained carrier, the toner concentration may be calculated.
Toners may possess suitable charge characteristics when exposed to extreme relative humidity (RH) conditions. The low humidity zone (C zone) may be about 10° C. and 15% RH, while the high humidity zone (A zone) may be about 28° C. and 85% RH.
Toners of the instant disclosure also may possess a parent toner charge per mass ratio (q/m) of from about −5 μC/g to about −90 μC/g, and a final toner charge after surface additive blending of from about −15 μC/g to about 80 μC/g.
Other desirable characteristics of a toner include storage stability, particle size integrity, high rate of fusing to the substrate or receiving member, sufficient release of the image from the photoreceptor, nondocument offset, use of smaller-sized particles and so on, and such characteristics may be obtained by including suitable reagents, suitable additives or both, and/or preparing the toner with particular protocols.
The dry toner particles, exclusive of external surface additives, may have the following characteristics: (1) volume average diameter (also referred to as “volume average particle diameter”) of from about 2.5 to about 20 μm, in embodiments, from about 2.75 to about 10 μm, in embodiments, from about 3 to about 7.5 μm; (2) number average geometric standard deviation (GSDn) and/or volume average geometric standard deviation (GSDv) of from about 1.18 to about 1.30, in embodiments, from about 1.21 to about 1.24; and (3) circularity of from about 0.9 to about 1.0 (measured with, for example, a Sysmex FPIA 2100 analyzer), in embodiments, from about 0.95 to about 0.985, in embodiments, from about 0.96 to about 0.98.
A. Composition
The toner particles thus formed may be formulated into a developer composition. For example, 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, with the remainder of the developer composition being the carrier. However, different toner and carrier percentages may be used to achieve a developer composition with desired characteristics.
1. Carrier
Examples of carrier particles for mixing with the toner particles include those particles that are capable of triboelectrically obtaining a charge of polarity opposite to that of the toner particles. Illustrative examples of suitable carrier particles include granular zircon, granular silicon, glass, steel, nickel, ferrites, iron ferrites, silicon dioxide, one or more polymers and the like. Other carriers include those disclosed in U.S. Pat. Nos. 3,847,604; 4,937,166; and 4,935,326.
In embodiments, the carrier particles may include a core with a coating thereover, which may be formed from a polymer or a mixture of polymers that are not in close proximity thereto in the triboelectric series, such as, those as taught herein or as known in the art. The coating may include fluoropolymers, such as polyvinylidene fluorides, terpolymers of styrene, methyl methacrylates, silanes, such as triethoxy silanes, tetrafluoroethylenes, other known coatings and the like. For example, coatings containing polyvinylidenefluoride, available, for example, as KYNAR 301F™, and/or polymethylmethacrylate (PMMA), for example, having a weight average molecular weight of about 300,000 to about 350,000, such as, commercially available from Soken, may be used. In embodiments, PMMA and polyvinylidenefluoride may be mixed in proportions of from about 30 to about 70 wt % to about 70 to about 30 wt %, in embodiments, from about 40 to about 60 wt % to about 60 to about 40 wt %. The coating may have a coating weight of, for example, from about 0.1 to about 5% by weight of the carrier, in embodiments, from about 0.5 to about 2% by weight of the carrier.
In embodiments, PMMA, for example, may be copolymerized with any desired monomer, so long as the resulting copolymer retains a suitable particle size. Suitable monomers include monoalkyl or dialkyl amines, such as, a dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, diisopropylaminoethyl methacrylate or butylaminoethyl methacrylate, and the like.
Various effective suitable means may be used to apply the polymer to the surface of the carrier core, for example, cascade roll mixing, tumbling, milling, shaking, electrostatic powder cloud spraying, fluidized bed mixing, electrostatic disc processing, electrostatic curtain processing, combinations thereof and the like. The mixture of carrier core particles and polymer then may be heated to enable the polymer to melt and to fuse to the carrier core. The coated carrier particles then may be cooled and thereafter classified to a desired particle size.
The carrier particles may be prepared by mixing the carrier core with polymer in an amount from about 0.05 to about 10% by weight, in embodiments, from about 0.01 to about 3% by weight, based on the weight of the coated carrier particle, until adherence thereof to the carrier core is obtained, for example, by mechanical impaction and/or electrostatic attraction.
In embodiments, suitable carriers may include a steel core, for example, of from about 25 to about 100 μm in size, in embodiments, from about 50 to about 75 μm in size, coated with about 0.5% to about 10% by weight, in embodiments, from about 0.7% to about 5% by weight of a polymer mixture including, for example, methylacrylate and carbon black, using the process described, for example, in U.S. Pat. Nos. 5,236,629 and 5,330,874.
Toners and developers may be combined with a number of devices ranging from enclosures or vessels, such as, a vial, a bottle, a flexible container, such as a bag or a package, and so on, to devices that serve more than a storage function.
A. Imaging Device Components
The toner compositions and developers of interest may be incorporated into devices dedicated, for example, to delivering same for a purpose, such as, forming an image. Hence, particularized toner delivery devices are known, see, for example, U.S. Pat. No. 7,822,370, and may contain a toner preparation or developer of interest. Such devices include cartridges, tanks, reservoirs and the like, and may be replaceable, disposable or reusable. Such a device may comprise a storage portion; a dispensing or delivery portion; and so on; along with various ports or openings to enable toner or developer addition to and removal from the device; an optional portion for monitoring amount of toner or developer in the device; formed or shaped portions to enable siting and seating of the device in, for example, an imaging device; and so on.
B. Toner or Developer Delivery Device
A toner or developer of interest may be included in a device dedicated to delivery thereof, for example, for recharging or refilling toner or developer in an imaging device component, such as, a cartridge, in need of toner or developer, see, for example, U.S. Pat. No. 7,817,944, wherein the imaging device component may be replaceable or reusable.
The toners or developers may be used for electrostatographic or electrophotographic processes, including those disclosed in U.S. Pat. No. 4,295,990, the disclosure of which hereby is 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, jumping single component development, hybrid scavengeless development (HSD) and the like. Those and similar development systems are within the purview of those skilled in the art.
Imaging processes include, for example, preparing an image with an electrophotographic device including, for example, one or more of a charging component, an imaging component, a photoconductive component, a developing component, a transfer component, a fusing component and so on. The electrophotographic device may include a high speed printer, a color printer and the like.
Once the image is formed with toners/developers via a suitable image development method, such as any of the aforementioned methods, the image then may be transferred to an image receiving medium or substrate, such as, a paper and the like. In embodiments, the fusing member or component, which may be of any desired or suitable configuration, such as, a drum or roller, a belt or web, a flat surface or platen, or the like, may be used to set the toner image on the substrate. Optionally, a layer of a liquid, such as, a fuser oil can be applied to the fuser member prior to fusing.
Color printers commonly use four housings carrying different colors to generate full color images based on black plus the standard printing colors, cyan, magenta and yellow. However, in embodiments, additional housings may be desirable, including image generating devices possessing five housings, six housings or more, thereby providing the ability to carry additional toner colors to print an extended range of colors (extended gamut).
The following Examples illustrate embodiments of the instant disclosure. The Examples are intended to be illustrative only and are not intended to limit the scope of the present disclosure. Parts and percentages are by weight unless otherwise indicated. As used herein, “room temperature,” (RT) refers to a temperature of from about 20° C. to about 30° C.
A black polyester EA toner was prepared at the 2 L bench scale (175 g dry theoretical toner). Two amorphous emulsions consisting of 97 g of polyester emulsion A (Mw=86,000, Tg onset=56° C., 35% solids) and 101 g, polyester emulsion B (Mw=19,400, Tg onset=60° C., 35% solids), 34 g crystalline polyester emulsion C (Mw—23,300, Mn—10,500, Tm—71° C., 35% solids) 5.06 g surfactant (DOWFAX®, commercially available from the Dow Chemical Company), 51 g wax (commercially available from The International Group, Inc. (IGI)), 96 g black pigment (Nipex 35) and 16 g cyan pigment (Pigment Blue 15:3 dispersion) were mixed, then the pH was adjusted to 4.2 using 0.3 M nitric acid. The resulting slurry was then homogenized for a total of 5 minutes at about 3000 to about 4000 rpm while adding 3.14 g aluminium sulphate (coagulant) mixed with 36.1 g of DI water. The slurry is then transferred to a 2 L Buchi reactor and set for mixing at 460 rpm. The slurry was aggregated at a batch temperature of 42° C. During aggregation, a shell-forming mixture (34 wt % of toner) comprised of the same amorphous emulsions as in the core was pH-adjusted to 3.3 with nitric acid and then added to the batch, where the batch was allowed to achieve a targeted particle size. Once the target particle size was achieved, the pH was adjusted to 7.8 with sodium hydroxide (NaOH) and EDTA to freeze aggregation. The process was continued with the reactor temperature (Tr) increased to 85° C., and the pH was adjusted to 6.5 using sodium acetate/acetic acid buffer (pH 5.7), for coalescence. After about two (2) hours, particles achieved a circularity of >0.956 and were quench-cooled with ice. Final toner particle size, GSDv and GSDn were 5.25/1.21/1.18, respectively. The fines (particles of about 1.3 to about 3 μm in size), coarse (particles >16 μm in size) and circularity were 0.57%, 0.15%, and 0.965, respectively. The toner is identified below as the, “high black toner.”
A black polyester EA toner was prepared at the 2 L bench scale (180 g dry theoretical toner). The two amorphous emulsions consisting of 88.5 g of polyester emulsion A (Mw—86,000, Tg onset—56° C., 35% solids) and 86 g of polyester emulsion B (Mw=19,400, Tg onset=60° C., 35% solids) 36 g crystalline emulsion C (Mw, =23,300, Mn=10,500, Tm=71° C., 35% solids), 2.4 g surfactant (DOWFAX), 55 g wax (IGI), 68 g black pigment (Nipex 35, 17% solids), 35 g Pigment Orange 34 dispersion (18% solids), 6.2 g Pigment Violet 23 dispersion (25.55 solids), 450 g DI water and 65 g cyan pigment (Pigment Blue 15.3 dispersion, 18% solids) were mixed, then the pH was adjusted to 4.2 using 0.3 M nitric acid. The slurry was then homogenized for a total of 5 minutes at 3000-4000 rpm while adding in the coagulant, 3.23 g aluminium sulphate mixed with 86 g DI. The slurry was then transferred to the 2 L Buchi and mixing was set at 460 rpm. The slurry was then aggregated at a batch temperature of 42° C. During aggregation, a shell (34 weight % of toner) comprised of the same amorphous emulsions as in the core was pH adjusted to 3.3 with nitric acid and added to the batch. Once at the targeted particle size, the pH of the mixture was adjusted to 7.8 using sodium hydroxide (NaOH) and EDTA. The reactor temperature (Tr) was increased to 85° C. and the pH was adjusted to pH 6.5 using sodium acetate/acetic acid buffer (pH 5.7). After about 2 hours, the particles achieved a circularity of >0.965 and were quench cooled with ice. Final particle size, GSDv, and GSDn were 5.31/1.19/1.21, respectively. The fines (1.3-3 μm), coarse (>16 μm), and circularity were 0.78%, 011%, and 0.973, respectively. The toner is identified below as the, “experimental toner.”
The two toners in Examples 1 (hyperpigmented with a large amount of black colorant) and 2 (hyperpigmented with lower amount of black colorant and a plurality of second colorants) were both washed in six deionized (DI) washes at room temperature and dried using a freeze drier.
A control toner comprising essentially the same reagents and using the same process as that of Example 1 was made, but containing about 6% black pigment (Nipex 35), as found in many commercially available black toners, identified below as, “the low black toner.”
Charging
Toners were blended with standard additives and tested in the A-zone for a stress case. Also, parent charge was measured in B-zone. Finally, dielectric loss was measured in the C-zone.
Parent and additive charge were identical for the low black control toner and the experimental toner of interest.
For comparison, the dielectric loss of the experimental toner was compared to that of the low black and the high black control toners. High dielectric loss is associated with poor transfer efficiency and poor IQ in A-zone.
The low black and experimental toners were tested in a Xerox 700 in the A-zone, which is the stress case for transfer efficiency and image quality. Despite the high pigment loading, the experimental toner has the same gloss as a function of TMA as does the low black toner, indicating that the addition of the color pigments is not affecting the gloss of the toner. The gloss data is compared in Table 3.
To obtain the same visible reflection optical density, ODr, a lower TMA is required, thus less toner is used on the print to get the same image blackness. On average, the required TMA reduction obtained with the experimental toner is about a 12% benefit as compared to the low black toner.
Second transfer efficiency in the Xerox 700 as a function of TMA for the Experimental hyperpigmented black toner is identical to that of the Low Black control toner, and is independent of tribo. The High Black toner with Nipex 35 at 8.7% loading had a transfer efficiency that averaged about 60% over the tribo range, and had lower transfer (50%) at the lowest tribo.
Mottle, which is sensitive to degradation in the A-zone, of the Experimental toner was equivalent to that of control Low Black toner at varying area coverage. On the other hand, the High Black control hyperpigmented toner with Nipex at 8.7% loading showed much worse IQ and had a mottle of about 80 at 100% AC at the same TC.
Based on the above, the following observations have been made:
The color mixture demonstrates utility in hyperpigmented toners for producing low TMA, for example, where the black toner layer on the print is significantly thinner than the toner diameter, reducing the amount of toner required on the print. The color mixture also demonstrates utility for toner, such as, black toner, with higher pigment loading, which also produces a thinner toner layer, but with a reduced toner size. In both cases, high toner pigment loading is required. It will be appreciated that several 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 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.
All references cited herein are herein incorporated by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| Parent | 13686965 | Nov 2012 | US |
| Child | 14494910 | US |
