# Patent

## Title
Emulsion aggregation toners

## Abstract

The present disclosure provides processes for producing toners. In embodiments, silica is added as a chelating agent during the toner production process contributing to enhanced triboelectric charging properties of the toner particles.

## Background
TECHNICAL FIELD
The present disclosure relates to processes for producing polyester resin based toners, including ultra low melt toners having desired image gloss characteristics. More specifically, the present disclosure provides processes for controlling image gloss of the polyester based toners by chelating aluminum with colloidal silica and adjusting the pH during the particle formation process to form particles.
BACKGROUND
Toners containing crystalline or semi-crystalline polyester resins with at least one amorphous resin have recently been shown to provide very desirable ultra low melt temperature fusing, which is important for both high-speed printing and lower fuser power consumption. These types of toners containing amorphous and crystalline polyesters have been used for both emulsion aggregation (EA) toners, and in conventional jetted toners. Combinations of amorphous and crystalline polyesters may provide toners with relatively low-melting point characteristics (sometimes referred to as low-melt, ultra low melt, or ULM), which allows for more energy-efficient and faster printing.
Emulsion aggregation coalescing processes for the preparation of toners are illustrated in a number of patents, such as U.S. Pat. Nos. 5,290,654, 5,278,020, 5,308,734, 5,344,738, 6,416,920, 6,576,389, 6,593,049, 6,743,559, 6,756,176, 6,830,860, 7,029,817, and 7,329,476, and U.S. Patent Application Publication Nos. 2006/0216626, 2008/0107990, 2008/0107989, 2008/0236446, and 2009/0047593. The disclosures of each of the foregoing patents are hereby incorporated by reference in their entirety.
It has been previously disclosed that polyester toner particle growth may be stopped or frozen by adjusting the pH of the solution followed by the addition of ethylene diamine tetraacetic acid (EDTA) sodium salt as a chelating agent. Some of the methods for freezing growth followed by chelating agent addition may negatively impact other properties of the toner particles, such as triboelectric charge and image gloss of the toner particles. It would thus be advantageous to provide an additive in addition to adjusting the pH that effectively controls polyester-based toner particle size and resulting image gloss on a substrate without adversely affecting other useful properties of the toner.
SUMMARY
The present disclosure provides processes for producing toner particles and toners produced by such processes. In embodiments, a process of the present disclosure may include contacting at least one polyester resin with at least one surfactant to form a mixture; aggregating the mixture to form particles; contacting the mixture with silica; adjusting the pH of the mixture; coalescing the particles to form toner particles; and recovering the toner particles.
In other embodiments, a process of the present disclosure may include contacting at least one amorphous polyester resin with at least one crystalline polyester resin in a mixture; aggregating the mixture to form particles; contacting the mixture with colloidal silica; adjusting the pH of the mixture with a basic solution; coalescing the particles to form toner particles; and recovering the toner particles.
In further embodiments, a process of the present disclosure may include contacting at least one amorphous polyester resin with at least one crystalline polyester resin in a mixture; aggregating the mixture to form particles; contacting the mixture with colloidal silica; stopping aggregation of the particles by adjusting the pH of the mixture to from about 3 to about 10; coalescing the particles to form toner particles; and recovering the toner articles.



BRIEF DESCRIPTION OF DRAWINGS
Various embodiments of the present disclosure will be described herein below with reference to the figures wherein:
FIG. 1 is a graph depicting image gloss as a function of fusing temperature of a toner produced with colloidal silica in accordance with the present disclosure compared with the same toner lacking the colloidal silica treatment used as a control; and
FIG. 2 is a graph depicting crease area as a function of fusing temperature of a toner produced with colloidal silica in accordance with the present disclosure compared with the same toner lacking the colloidal silica treatment used as a control.



DETAILED DESCRIPTION
The present disclosure provides for the use of colloidal silica in a toner production process, such as an emulsion aggregation process for the preparation of ultra low melt (ULM) polyester toners. During emulsion aggregation processes of ULM polyester toners, latex emulsions are mixed with optional waxes and pigments and other additives. The mixture is then homogenized with the addition of a coagulant to form pre-aggregated particles. The pre-aggregate is then heated to promote particle growth until the desired particle size is obtained. Once the desired size is achieved, particle growth is stopped, i.e., frozen by adjusting the pH of the mixture. In accordance with the present disclosure, colloidal silica is added to the emulsion, after adjusting the pH, to enhance image gloss and triboelectric charge of the toner particles. Further pH adjustment is optional and depends on the process requirement after silica addition. Silica also removes alumina from the toner particles thereby achieving desired image gloss levels in the toner.
The present disclosure provides for use of colloidal silica in lieu of ethylene diamine tetraacetic acid (EDTA) sodium salt, as a chelating agent for polyester based toner particles. The use of silica instead of EDTA improves the triboelectric charge of the toner particles. In addition, unlike EDTA sodium salt, silica does not deposit sodium ions on the surface of the toner and thus the resulting toner contained less residual sodium ions and this in fact helps improve toner charging properties.
Resins
Toners of the present disclosure may include any latex resin suitable for use in forming a polyester toner. Such resins, in turn, may be made of any suitable monomer. In embodiments, the polymer utilized to form the resin may be a polyester resin. Suitable polyester resins include, for example, sulfonated, non-sulfonated, crystalline, amorphous, combinations thereof, and the like. The polyester resins may be linear, branched, combinations thereof, and the like. Polyester resins may include, in embodiments, those resins described in U.S. Pat. Nos. 6,593,049 and 6,756,176, the disclosures of each of which are hereby incorporated by reference in their entirety. Suitable resins may also include a mixture of an amorphous polyester resin or resins 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 its entirety.
In embodiments, a resin utilized in forming a toner may include an amorphous polyester resin. In embodiments, the resin may be a polyester resin formed by reacting a diol with a diacid or diester in the presence of an optional catalyst.
Examples of organic diols selected for the preparation of amorphous resins 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, 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. The aliphatic diol is, for example, selected in an amount of from about 45 to about 50 mole percent of the resin, and the alkali sulfo-aliphatic diol can be selected in an amount of from about 1 to about 10 mole percent of the resin.
Examples of diacid or diesters selected for the preparation of the amorphous polyester include dicarboxylic acids or diesters selected from the group consisting of terephthalic acid, phthalic acid, isophthalic acid, fumaric acid, maleic acid, itaconic acid, succinic acid, succinic anhydride, dodecylsuccinic acid, dodecylsuccinic anhydride, dodecenylsuccinic acid, dodecenylsuccinic 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, dimethyl dodecenylsuccinate, and mixtures thereof. The organic diacid or diester is selected, for example, from about 45 to about 52 mole percent of the resin.
Examples of suitable polycondensation catalyst for either the amorphous polyester resin include tetraalkyl titanates, dialkyltin oxide such as dibutyltin oxide, tetraalkyltin such as dibutyltin dilaurate, dialkyltin oxide hydroxide such as butyltin oxide hydroxide, aluminum alkoxides, alkyl zinc, dialkyl zinc, zinc oxide, stannous oxide, or mixtures thereof; and which catalysts are selected 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 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), a copoly(propoxylated bisphenol A co-fumarate)-copoly(propoxylated bisphenol A co-terephthalate), a terpoly(propoxylated bisphenol A co-fumarate)-terpoly(propoxylated bisphenol A co-terephthalate)-terpoly-(propoxylated bisphenol A co-dodecylsuccinate), and combinations thereof. In embodiments, the amorphous resin utilized in the core may be linear or branched.
In embodiments, a suitable amorphous resin may include alkoxylated bisphenol A fumarate/terephthalate based polyesters and copolyester resins. In embodiments, a suitable amorphous polyester resin may be a copoly(propoxylated bisphenol A co-fumarate)-copoly(propoxylated bisphenol A co-terephthalate) resin having the following formula (I):




wherein R may be hydrogen or a methyl group, and m and n represent random units of the copolymer and m may be from about 2 to 10, and n may be from about 2 to 10.

An example of a linear copoly(propoxylated bisphenol A co-fumarate)-copoly(propoxylated bisphenol A co-terephthalate) which may be utilized as a latex resin is available under the trade name SPARII from Resana S/A Industrias Quimicas, Sao Paulo Brazil. Other propoxylated bisphenol A fumarate resins that may be utilized and are commercially available include GTUF and FPESL-2 from Kao Corporation, Japan, and EM181635 from Reichhold, Research Triangle Park, N.C. and the like.
In embodiments, the amorphous polyester resin may be a saturated or unsaturated amorphous polyester resin. Illustrative examples of saturated and unsaturated amorphous polyester resins selected for the process and particles of the present disclosure include any of the various amorphous polyesters, such as polyethylene-terephthalate, polypropylene-terephthalate, polybutylene-terephthalate, polypentylene-terephthalate, polyhexalene-terephthalate, polyheptadene-terephthalate, polyoctalene-terephthalate, polyethylene-isophthalate, polypropylene-isophthalate, polybutylene-isophthalate, polypentylene-isophthalate, polyhexalene-isophthalate, polyheptadene-isophthalate, polyoctalene-isophthalate, polyethylene-sebacate, polypropylene sebacate, polybutylene-sebacate, polyethylene-adipate, polypropylene-adipate, polybutylene-adipate, polypentylene-adipate, polyhexalene-adipate, polyheptadene-adipate, polyoctalene-adipate, polyethylene-glutarate, polypropylene-glutarate, polybutylene-glutarate, polypentylene-glutarate, polyhexalene-glutarate, polyheptadene-glutarate, polyoctalene-glutarate polyethylene-pimelate, polypropylene-pimelate, polybutylene-pimelate, polypentylene-pimelate, polyhexalene-pimelate, polyheptadene-pimelate, poly(ethoxylated bisphenol A-fumarate), poly(ethoxylated bisphenol A-succinate), poly(ethoxylated bisphenol A-adipate), poly(ethoxylated bisphenol A-glutarate), poly(ethoxylated bisphenol A-terephthalate), poly(ethoxylated bisphenol A-isophthalate), poly(ethoxylated bisphenol A-dodecenylsuccinate), poly(propoxylated bisphenol A-fumarate), poly(propoxylated bisphenol A-succinate), poly(propoxylated bisphenol A-adipate), poly(propoxylated bisphenol A-glutarate), poly(propoxylated bisphenol A-terephthalate), poly(propoxylated bisphenol A-isophthalate), poly(propoxylated bisphenol A-dodecenylsuccinate), SPAR (Dixie Chemicals), BECKOSOL (Reichhold Inc), ARAKOTE (Ciba-Geigy Corporation), HETRON (Ashland Chemical), PARAPLEX (Rohm & Haas), POLYLITE (Reichhold Inc), PLASTHALL (Rohm & Haas), CYGAL (American Cyanamide), ARMCO (Armco Composites), ARPOL (Ashland Chemical), CELANEX (Celanese Eng), RYNITE (DuPont), STYPOL (Freeman Chemical Corporation) and combinations thereof. The resins can also be functionalized, such as carboxylated, sulfonated, or the like, and particularly such as sodio sulfonated, if desired.
The amorphous polyester resin may be a branched resin. As used herein, the terms “branched” or “branching” includes branched resin and/or cross-linked resins. Branching agents for use in forming these branched resins 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, and 1,2,7,8-octanetetracarboxylic acid, acid anhydrides thereof, and lower alkyl esters thereof, 1 to about 6 carbon atoms; a multivalent polyol such as sorbitol, 1,2,3,6-hexanetetrol, 1,4-sorbitane, pentaerythritol, dipentaerythritol, tripentaerythritol, sucrose, 1,2,4-butanetriol, 1,2,5-pentatriol, glycerol, 2-methylpropanetriol, 2-methyl-1,2,4-butanetriol, trimethylolethane, trimethylolpropane, 1,3,5-trihydroxymethylbenzene, mixtures thereof, and the like. The branching agent amount selected is, for example, from about 0.1 to about 5 mole percent of the resin.
Linear or branched unsaturated polyesters selected for reactions include both saturated and unsaturated diacids (or anhydrides) and dihydric alcohols (glycols or diols). The resulting unsaturated polyesters are reactive (for example, crosslinkable) on two fronts: (i) unsaturation sites (double bonds) along the polyester chain, and (ii) functional groups such as carboxyl, hydroxy, and the like groups amenable to acid-base reactions. Typical unsaturated polyester resins may be prepared by melt polycondensation or other polymerization processes using diacids and/or anhydrides and diols.
In embodiments, a suitable amorphous resin utilized in a toner of the present disclosure may be a low molecular weight amorphous resin, sometimes referred to, in embodiments, as an oligomer, having a weight average molecular weight (Mw) of from about 500 daltons to about 10,000 daltons, in embodiments from about 1000 daltons to about 5000 daltons, in other embodiments from about 1500 daltons to about 4000 daltons.
The low molecular weight amorphous resin may possess a glass transition temperature (Tg) of from about 60° C. to about 70° C., in embodiments from about 62° C. to about 64° C. These low molecular weight amorphous resins may be referred to, in embodiments, as a high Tg amorphous resin.
The low molecular weight amorphous resin may possess a softening point of from about 105° C. to about 118° C., in embodiments from about 106° C. to about 114° C.
In other embodiments, an amorphous resin utilized in forming a toner of the present disclosure may be a high molecular weight amorphous resin. As used herein, the high molecular weight amorphous polyester resin may have, for example, a number average molecular weight (Mn), as measured by gel permeation chromatography (GPC) of, for example, from about 1,000 to about 10,000, in embodiments from about 2,000 to about 9,000, in embodiments from about 3,000 to about 8,000, and in embodiments from about 6,000 to about 7,000. The weight average molecular weight (Mw) of the resin is greater than 45,000, for example, from about 45,000 to about 150,000, in embodiments from about 50,000 to about 100,000, in embodiments from about 63,000 to about 94,000, and in embodiments from about 68,000 to about 85,000, as determined by GPC using polystyrene standard. The polydispersity index (PD) is greater than about 3, such as, for example, in embodiments from about 3 to about 20, in embodiments from about 4 to about 10, and in embodiments from about 5 to about 8, as measured by GPC versus standard polystyrene reference resins. The PD index is the ratio of the weight-average molecular weight (Mw) to the number-average molecular weight (Mn). The low molecular weight amorphous polyester resins may have an acid value of from about 8 to about 20 mg KOH/g, in embodiments from about 9 to about 16 mg KOH/g, and in embodiments from about 11 to about 15 mg KOH/g. The high molecular weight amorphous polyester resins, which are available from a number of sources, can possess various softening points of, for example, from about 30° C. to about 140° C., in embodiments from about 75° C. to about 130° C., in embodiments from about 100° C. to about 125° C., and in embodiments from about 115° C. to about 124° C.
High molecular weight amorphous resins may possess a glass transition temperature of from about 53° C. to about 59° C., in embodiments from about 54.5° C. to about 57° C. These high molecular weight amorphous resins may be referred to, in embodiments, as a low Tg amorphous resin.
In embodiments, a combination of low Tg and high Tg amorphous resins may be used to form a toner of the present disclosure. The ratio of low Tg amorphous resin to high Tg amorphous resin may be from about 0:100 to about 100:0, in embodiments from about 30:70 to about 50:50. In embodiments, the combined amorphous resins may have a melt viscosity of from about 10 to about 1,000,000 Pa*S at about 130° C., in embodiments from about 50 to about 100,000 Pa*S.
The amorphous resin is generally present in the toner composition in various suitable amounts, such as from about 60 to about 90 weight percent, in embodiments from about 50 to about 70 weight percent, of the toner or of the solids.
In embodiments, the toner composition may include at least one crystalline resin. As used herein, “crystalline” refers to a polyester with a three dimensional order. “Semicrystalline resins” as used herein refers to resins with a crystalline percentage of, for example, from about 10 to about 90%, in embodiments from about 12 to about 70%. Further, as used herein, “crystalline polyester resins” and “crystalline resins” encompass both crystalline resins and semicrystalline resins, unless otherwise specified.
In embodiments, the crystalline polyester resin is a saturated crystalline polyester resin or an unsaturated crystalline polyester resin.
For forming a crystalline polyester, suitable organic diols include aliphatic diols having 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, ethylene glycol, combinations 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 of the resin.
Examples of organic diacids or diesters selected for the preparation of the crystalline resins include oxalic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, fumaric acid, maleic acid, dodecanedioic acid, sebacic acid, 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 combinations 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 55 mole percent, in embodiments from about 45 to about 53 mole percent.
Examples of polyester-based crystalline resins include, but are not limited to, 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), alkali copoly(5-sulfoisophthaloyl)-copoly(ethylene-adipate), 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), and combinations thereof. 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 polyester resins, which are available from a number of sources, 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 resins may have, for example, 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, in embodiments from about 3,000 to about 15,000, and in embodiments from about 6,000 to about 12,000. The weight average molecular weight (Mw) of the resin is 50,000 or less, for example, from about 2,000 to about 50,000, in embodiments from about 3,000 to about 40,000, in embodiments from about 10,000 to about 30,000 and in embodiments from about 21,000 to about 24,000, as determined by GPC using polystyrene standards. The molecular weight distribution (Mw/Mn) of the crystalline resin is, for example, from about 2 to about 6, in embodiments from about 3 to about 4. The crystalline polyester resins may have an acid value of about 2 to about 20 mg KOH/g, in embodiments from about 5 to about 16 mg KOH/g, and in embodiments from about 8 to about 15 mg KOH/g. The acid value (or neutralization number) is the mass of potassium hydroxide (KOH) in milligrams that is required to neutralize one gram of the crystalline polyester resin.
Suitable crystalline polyester resins include those disclosed in U.S. Pat. No. 7,329,476 and U.S. Patent Application Publication Nos. 2006/0216626, 2008/0107990, 2008/0236446 and 2009/0047593, each of which is hereby incorporated by reference in their entirety. In embodiments, a suitable crystalline resin may include a resin composed of ethylene glycol or nonanediol and a mixture of dodecanedioic acid and fumaric acid co-monomers with the following formula (II):




wherein b is from about 5 to about 2000 and d is from about 5 to about 2000.

If semicrystalline polyester resins are employed herein, the semicrystalline resin may include poly(3-methyl-1-butene), poly(hexamethylene carbonate), poly(ethylene-p-carboxy phenoxy-butyrate), poly(ethylene-vinyl acetate), poly(docosyl acrylate), poly(dodecyl acrylate), poly(octadecyl acrylate), poly(octadecyl methacrylate), poly(behenylpolyethoxyethyl methacrylate), poly(ethylene adipate), poly(decamethylene adipate), poly(decamethylene azelaate), poly(hexamethylene oxalate), poly(decamethylene oxalate), poly(ethylene oxide), poly(propylene oxide), poly(butadiene oxide), poly(decamethylene oxide), poly(decamethylene sulfide), poly(decamethylene disulfide), poly(ethylene sebacate), poly(decamethylene sebacate), poly(ethylene suberate), poly(decamethylene succinate), poly(eicosamethylene malonate), poly(ethylene-p-carboxy phenoxy-undecanoate), poly(ethylene dithionesophthalate), poly(methyl ethylene terephthalate), poly(ethylene-p-carboxy phenoxy-valerate), poly(hexamethylene-4,4′-oxydibenzoate), poly(10-hydroxy capric acid), poly(isophthalaldehyde), poly(octamethylene dodecanedioate), poly(dimethyl siloxane), poly(dipropyl siloxane), poly(tetramethylene phenylene diacetate), poly(tetramethylene trithiodicarboxylate), poly(trimethylene dodecane dioate), poly(m-xylene), poly(p-xylylene pimelamide), and combinations thereof.
A crystalline polyester resin in a toner particle of the present disclosure may be present in an amount of from about 1 to about 15 percent by weight, in embodiments from about 5 to about 10 percent by weight, and in embodiments from about 6 to about 8 percent by weight, of the toner particles (that is, toner particles exclusive of external additives and water).
As noted above, in embodiments a toner of the present disclosure may also include at least one high molecular weight branched or cross-linked amorphous polyester resin. This high molecular weight resin may include, in embodiments, for example, a branched amorphous resin or amorphous polyester, a cross-linked amorphous resin or amorphous polyester, or mixtures thereof, or a non-cross-linked amorphous polyester resin that has been subjected to cross-linking. In accordance with the present disclosure, from about 1% by weight to about 100% by weight of the high molecular weight amorphous polyester resin may be branched or cross-linked, in embodiments from about 2% by weight to about 50% by weight of the higher molecular weight amorphous polyester resin may be branched or cross-linked.
In embodiments, toner particles of the present disclosure may have a core including from about 10% by weight to about 90% by weight of a low molecular weight, high Tg, amorphous resin, in embodiments from about 20% by weight to about 80% by weight of a low molecular weight, high Tg, amorphous resin, in combination with from about 10% by weight to about 90% by weight of a high molecular weight, low Tg, amorphous resin, in embodiments from about 20% by weight to about 80% by weight of a high molecular weight, low Tg, amorphous resin.
Such toner particles may also include a shell including from about 20% by weight to about 45% by weight of a low molecular weight, high Tg, amorphous resin, in embodiments from about 28% by weight to about 34% by weight of an amorphous resin which, in embodiments, may be a low molecular weight, high Tg, resin, optionally in combination with a high molecular weight, low Tg, amorphous resin.
As noted above, in embodiments, the resin particles may be formed by emulsion aggregation methods. Utilizing such methods, the resin may be present in a resin emulsion, which may then be combined with other components and additives to form a toner of the present disclosure.
Toner
The resin described above may be utilized to form toner compositions. Such toner compositions may include optional colorants, waxes, and other additives. Toners may be formed utilizing any method within the purview of those skilled in the art.
Surfactants
In embodiments, colorants, waxes, and other additives utilized to form toner compositions may be in dispersions including surfactants. Moreover, toner particles may be formed by emulsion aggregation methods where the resin and other components of the toner are placed in one or more surfactants, an emulsion is formed, toner particles are aggregated, coalesced, optionally washed and dried, and recovered.
One, two, or more surfactants may be utilized. The surfactants may be selected from ionic surfactants and nonionic surfactants. Anionic surfactants and cationic surfactants are encompassed by the term “ionic surfactants.” In embodiments, the surfactant may be utilized so that it is present in an amount of from about 0.01% to about 5% by weight of the toner composition, for example from about 0.75% to about 4% by weight of the toner composition, in embodiments from about 1% to about 3% by weight of the toner composition.
Where utilized, a resin emulsion may include one, two, or more surfactants. In embodiments, the surfactant may be added as a solid or as a solution with a concentration of from about 5% to about 100% (pure surfactant) by weight, in embodiments, from about 10% to about 95% by weight. In embodiments, the surfactant may be utilized so that it is present in an amount of from about 0.01% to about 20% by weight of the resin, in embodiments, from about 0.1% to about 16% by weight of the resin, in other embodiments, from about 1% to about 14% by weight of the resin.
Examples of nonionic surfactants that can be utilized include, for example, 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, dialkylphenoxy poly(ethyleneoxy) ethanol, available from Rhone-Poulenc as IGEPAL CA-210TM, IGEPAL CA-520TM, IGEPAL CA-720TM, IGEPAL CO-890TM, IGEPAL CO-720TM, IGEPAL CO-290TM, IGEPAL CA-210TM, ANTAROX 890TM and ANTAROX 897TM. Other examples of suitable nonionic surfactants include a block copolymer of polyethylene oxide and polypropylene oxide, including those commercially available as SYNPERONIC PE/F, in embodiments SYNPERONIC PE/F 108.
Anionic surfactants which may be utilized include sulfates and sulfonates, sodium dodecylsulfate (SDS), sodium dodecylbenzene sulfonate, sodium dodecylnaphthalene sulfate, dialkyl benzenealkyl sulfates and sulfonates, acids such as abitic acid available from Aldrich, NEOGEN RTM, NEOGEN RKTM, and/or NEOGEN SCTM obtained from Daiichi Kogyo Seiyaku, combinations thereof, and the like. Other suitable anionic surfactants include, in embodiments, DOWFAXTM 2A1, an alkyldiphenyloxide disulfonate from The Dow Chemical Company, and/or TAYCA POWER BN2060 from Tayca Corporation (Japan), which are branched sodium dodecyl benzene sulfonates. Combinations of these surfactants and any of the foregoing anionic surfactants may be utilized in embodiments.
Examples of the cationic surfactants, which are usually positively charged, 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, C12, C15, C17 trimethyl ammonium bromides, halide salts of quaternized polyoxyethylalkylamines, dodecylbenzyl triethyl ammonium chloride, MIRAPOLTM and ALKAQUATTM, available from Alkaril Chemical Company, SANIZOLTM (benzalkonium chloride), available from Kao Chemicals, and the like, and mixtures thereof.
Colorants
As the optional colorant to be added, 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 percent by weight of the toner, or from about 1 to about 15 weight percent of the toner, or from about 3 to about 10 percent by weight of the toner.
As examples of suitable colorants, mention may be made of carbon black like REGAL 330®; magnetites, such as Mobay magnetites MO8029TM, MO8060TM; Columbian magnetites; MAPICO BLACKSTM and surface treated magnetites; Pfizer magnetites CB4799TM, CB5300TM, CB5600TM, MCX6369TM; Bayer magnetites, BAYFERROX 8600TM, 8610TM; Northern Pigments magnetites, NP-604TM, NP-608TM; Magnox magnetites TMB-100TM, or TMB-104TM; and the like. As colored pigments, there can 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 are generally used as water based pigment dispersions.
Specific examples of pigments include SUNSPERSE 6000, FLEXIVERSE and AQUATONE water based pigment dispersions from SUN Chemicals, HELIOGEN BLUE L6900TM, D6840TM, D7080TM, D7020TM, PYLAM OIL BLUETM, PYLAM OIL YELLOWTM, PIGMENT BLUE 1TM available from Paul Uhlich & Company, Inc., PIGMENT VIOLET 1TM, PIGMENT RED 48TM, LEMON CHROME YELLOW DCC 1026TM, E.D. TOLUIDINE REDTM and BON RED CTM available from Dominion Color Corporation, Ltd., Toronto, Ontario, NOVAPERM YELLOW FGLTM, HOSTAPERM PINK ETM from Hoechst, and CINQUASIA MAGENTATM available from E.I. DuPont de Nemours & Company, and the like. Generally, colorants that can be selected are black, cyan, magenta, or yellow, and mixtures thereof. Examples of magentas are 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 copper tetra(octadecyl sulfonamido)phthalocyanine, x-copper phthalocyanine pigment listed in the Color Index as CI 74160, CI Pigment Blue, Pigment Blue 15:3, and Anthrathrene Blue, identified in the Color Index as CI 69810, Special Blue X-2137, and the like. Illustrative examples of yellows are 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 BLACKTM, and cyan components may also be selected as colorants. Other known colorants can 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), combinations of the foregoing, and the like.
Wax
Optionally, a wax may also be combined with the resin and optional colorant in forming toner particles. When included, the wax may be present in an amount of, for example, from about 1 weight percent to about 25 weight percent of the toner particles, in embodiments from about 5 weight percent to about 20 weight percent 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 POLYWAXTM polyethylene waxes from Baker Petrolite, wax emulsions available from Michaelman, Inc. and the Daniels Products Company, EPOLENE N-15TM commercially available from Eastman Chemical Products, Inc., and VISCOL 550-PTM, 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, and 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 6550TM, SUPERSLIP 6530TM available from Micro Powder Inc., fluorinated waxes, for example POLYFLUO 190TM, POLYFLUO 200TM, POLYSILK 19TM, POLYSILK 14TM available from Micro Powder Inc., mixed fluorinated, amide waxes, for example MICROSPERSION 19TM also available from Micro Powder Inc., imides, esters, quaternary amines, carboxylic acids or acrylic polymer emulsion, for example JONCRYL 74TM, 89TM, 130TM, 537TM, and 538TM, 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 may also be used in embodiments. Waxes may be included as, for example, fuser roll release agents.
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 disclosures of each of which are hereby incorporated by reference in their entirety. In embodiments, toner compositions and toner particles may be prepared by aggregation and coalescence processes in which small-size 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 colorant, an optional wax and any other desired or required additives, and emulsions including the resins described above, optionally in surfactants as described above, and then coalescing the aggregate mixture. A mixture may be prepared by adding a colorant and optionally a wax or other materials, which may also be optionally 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 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 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 6,000 revolutions per minute. Homogenization may be accomplished by any suitable means, including, for example, an IKA ULTRA TURRAX T50 probe homogenizer.
Following the preparation of the above mixture, an aggregating agent may be added to the mixture. Any suitable aggregating agent may be utilized to form a toner. Suitable aggregating agents include, for example, aqueous solutions of a divalent cation or a multivalent cation material. The aggregating agent may be, for example, an inorganic cationic aggregating agent such as 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, and 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.
Suitable examples of organic cationic aggregating agents include, for example, dialkyl benzenealkyl ammonium chloride, lauryl trimethyl ammonium chloride, alkylbenzyl methyl ammonium chloride, alkyl benzyl dimethyl ammonium bromide, benzalkonium chloride, cetyl pyridinium bromide, C12, C15, C17 trimethyl ammonium bromides, halide salts of quaternized polyoxyethylalkylamines, dodecylbenzyl triethyl ammonium chloride, combinations thereof, and the like.
Other suitable aggregating agents also include, but are not limited to, tetraalkyl titinates, dialkyltin oxide, tetraalkyltin oxide hydroxide, dialkyltin oxide hydroxide, aluminum alkoxides, alkyl zinc, dialkyl zinc, zinc oxides, stannous oxide, dibutyltin oxide, dibutyltin oxide hydroxide, tetraalkyl tin, combinations thereof, and the like. Where the aggregating agent is a polyion aggregating agent, the agent may have any desired number of polyion atoms present. For example, in embodiments, suitable polyaluminum compounds have from about 2 to about 13, in other embodiments, from about 3. to about 8, aluminum ions present in the compound.
The aggregating agent may be added to the mixture utilized to form a toner in an amount of, for example, from about 0% to about 10% by weight of the resin in the mixture, in embodiments from about 0.2% to about 8% by weight of the resin in the mixture, in other embodiments from about 0.5% to about 5% by weight of the resin in the mixture. This should provide a sufficient amount of agent for aggregation.
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 to be obtained as determined prior to formation, and the particle size being monitored during the growth process until such particle size is reached. 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 this temperature for a time of 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 aggregated particles. Once the predetermined desired particle size is reached, then the growth process is halted.
The 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 of from about 40° C. to about 90° C., in embodiments from about 45° C. to about 80° C., which may be below the glass transition temperature of the resin as discussed above.
Once the desired final size of the toner particles is achieved, the pH of the mixture may be adjusted with a base to a value of from about 3 to about 10, and in embodiments from about 5 to about 9. 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, combinations thereof, and the like.
In embodiments, colloidal silica may be added to the emulsion as a chelating agent, forming metal complexes with alumina, thereby extracting alumina and achieving desired toner image gloss. Alumina is generally present as the cation of the coagulant (e.g., aluminum sulfate). Silica may be added as, colloidal silica, for example SNOWTEXTM OL and SNOWTEXTM OS colloidal silica available from Nissan Chemical Industries, Ltd., combinations thereof, and the like. Silica may be present in an amount from about 1% to about 15% by weight of the resin (e.g., amorphous and crystalline resins present) in the mixture, in embodiments from about 5% to about 10% by weight of the resin in the mixture. The silica may include a solids content, in embodiments, from about 1% to about 40% solids, in embodiments, from about 5% to about 25% solids. In embodiments, the silica particles may be colloidal silica particles, i.e., silica particles having a volume average particle size in an aqueous colloidal dispersion as measured by any suitable technique, such as a Coulter Counter, of from about 1 nm to about 100 nm, in embodiments from about 10 nm to about 80 nm.
Shell Resin
In embodiments, after aggregation, but prior to coalescence, a resin coating may be applied to the aggregated particles to form a shell thereover. In embodiments, the core may thus include a crystalline resin, as described above. Any resin described above may be utilized as the shell. In embodiments, a polyester amorphous resin latex as described above may be included in the shell. In embodiments, the polyester amorphous resin latex described above may be combined with a different resin, and then added to the particles as a resin coating to form a shell.
In embodiments, resins which may be utilized to form a shell include, but are not limited to, a crystalline resin latex described above, and/or the amorphous resins described above. In embodiments, an amorphous resin which may be utilized to form a shell in accordance with the present disclosure includes an amorphous polyester, optionally in combination with a crystalline polyester resin latex described above. Multiple resins may be utilized in any suitable amounts. In embodiments, a first amorphous polyester resin, for example an amorphous resin of formula I above, may be present in an amount of from about 20 percent by weight to about 100 percent by weight of the total shell resin, in embodiments from about 30 percent by weight to about 90 percent by weight of the total shell resin. Thus, in embodiments, a second resin may be present in the shell resin in an amount of from about 0 percent by weight to about 80 percent by weight of the total shell resin, in embodiments from about 10 percent by weight to about 70 percent by weight of 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 resins utilized to form the shell may be in an emulsion including any surfactant described above. The emulsion possessing the resins, optionally the solvent based and or non solvent based amorphous and/or crystalline polyester resins latexes described above, may be combined with the aggregated particles described above 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 of 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 of 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 of from about 1 percent by weight to about 80 percent by weight of the latex particles, in embodiments of from about 10 percent by weight to about 40 percent by weight of the latex particles, in still further embodiments from about 20 percent by weight to about 35 percent by weight of the latex particles.
Coalescence
Following aggregation to the desired particle size and application of any optional shell, the particles may then be coalesced to the desired final shape, the coalescence being achieved by, for example, heating the mixture to a temperature of 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 glass transition temperature of the resins utilized to form the toner particles, and/or reducing the stirring, for example to from about 1000 rpm to about 30 rpm, in embodiments from about 800 rpm to about 50 rpm. Coalescence may be accomplished over a period of from about 0.01 to about 9 hours, in embodiments from about 0.1 to about 4 hours.
Drying
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 may be optionally washed with water, and then dried. Drying may be accomplished by any suitable method for drying including, for example, freeze-drying, a flash drying system known as an Aljet Thermajet dryer Model 4, commercially available from Fluid Energy Processing and Equipment company, combinations thereof, and the like.
In embodiments, the final size of the toner particles may be of from about 2 μm to about 12 μm, in embodiments of from about 3 μm to about 10 μm.
Other Additives
In embodiments, the toner particles may also contain other optional additives, as desired or required. For example, the toner may include positive or negative charge control agents, for example in an amount of from about 0.1 to about 10% by weight of the toner, in embodiments from about 1 to about 3% by weight of the toner. Examples of suitable charge control agents include quaternary ammonium compounds inclusive of alkyl pyridinium halides; bisulfates; alkyl pyridinium compounds, including those disclosed in U.S. Pat. No. 4,298,672, the disclosure of which is hereby incorporated by reference in its entirety; organic sulfate and sulfonate compositions, including those disclosed in U.S. Pat. No. 4,338,390, the disclosure of which is hereby incorporated by reference in its entirety; cetyl pyridinium tetrafluoroborates; distearyl dimethyl ammonium methyl sulfate; aluminum salts such as BONTRON E84TM or E88TM (Orient Chemical Industries, Ltd.); combinations thereof, and the like.
Additional flow aid additives may be blended with the recovered toner particles after drying as described above. These additional flow aid additives may thus be present on the surface of the toner particles. Examples of these additives include metal oxides such as titanium oxide, silicon oxide, aluminum oxides, cerium oxides, tin oxide, mixtures thereof, and the like; colloidal and amorphous silicas, such as AEROSIL®, metal salts and metal salts of fatty acids inclusive of zinc stearate, calcium stearate, or long chain alcohols such as UNILIN 700, and combinations thereof.
In general, silica may be applied to the toner surface for toner flow, triboelectric charge enhancement, admix control, improved development and transfer stability, and higher toner blocking temperature. TiO2 may be applied for improved relative humidity (RH) stability, triboelectric charge control and improved development and transfer stability. Zinc stearate, calcium stearate and/or magnesium stearate may optionally also be used as an external additive for providing lubricating properties, developer conductivity, triboelectric charge enhancement, enabling higher toner charge and charge stability by increasing the number of contacts between toner and carrier particles. In embodiments, a commercially available zinc stearate known as Zinc Stearate L, obtained from Ferro Corporation, may be used. The external surface additives may be used with or without a coating.
Each of these external additives may be present in an amount of from about 0.1% by weight to about 5% by weight of the toner, in embodiments of from about 0.25% by weight to about 3% by weight of the toner. In embodiments, the toners may include, for example, from about 0.1% by weight to about 5% by weight titania, from about 0.1% by weight to about 8% by weight silica, and from about 0.1% by weight to about 4% by weight zinc stearate.
Suitable additives include those disclosed in U.S. Pat. Nos. 3,590,000, and 6,214,507, the disclosures of each of which are hereby incorporated by reference in their entirety.
The following Examples 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. As used herein, “room temperature” refers to a temperature of from about 20° C. to about 25° C.
Developers
The toner particles thus obtained 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.
Carriers
Examples of carrier particles that can be utilized for mixing with the toner include those particles that are capable of triboelectrically obtaining a charge of opposite polarity 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, and the like. Other carriers include those disclosed in U.S. Pat. Nos. 3,847,604, 4,937,166, and 4,935,326.
The selected carrier particles can be used with or without a coating. In embodiments, the carrier particles may include a core with a coating thereover which may be formed from a mixture of polymers that are not in close proximity thereto in the triboelectric series. The coating may include fluoropolymers, such as polyvinylidene fluoride resins, terpolymers of styrene, methyl methacrylate, and/or silanes, such as triethoxy silane, tetrafluoroethylenes, other known coatings and the like. For example, coatings containing polyvinylidenefluoride, available, for example, as KYNAR 301FTM, and/or polymethylmethacrylate, 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, polyvinylidenefluoride and polymethylmethacrylate (PMMA) may be mixed in proportions of from about 30 to about 70 weight % to about 70 to about 30 weight %, in embodiments from about 40 to about 60 weight % to about 60 to about 40 weight %. 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 may optionally be copolymerized with any desired comonomer, so long as the resulting copolymer retains a suitable particle size. Suitable comonomers can include monoalkyl, or dialkyl amines, such as a dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, diisopropylaminoethyl methacrylate, t-butylaminoethyl methacrylate, and the like. The carrier particles may be prepared by mixing the carrier core with polymer in an amount from about 0.05 to about 10 percent by weight, in embodiments from about 0.01 percent to about 3 percent by weight, based on the weight of the coated carrier particles, until adherence thereof to the carrier core by mechanical impaction and/or electrostatic attraction.
Various effective suitable means can be used to apply the polymer to the surface of the carrier core particles, for example, cascade roll mixing, tumbling, milling, shaking, electrostatic powder cloud spraying, fluidized bed, electrostatic disc processing, electrostatic curtain, combinations thereof, and the like. The mixture of carrier core particles and polymer may then be heated to enable the polymer to melt and fuse to the carrier core particles. The coated carrier particles may then be cooled and thereafter classified to a desired particle size.
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 conductive polymer mixture including, for example, methylacrylate and carbon black using the process described in U.S. Pat. Nos. 5,236,629 and 5,330,874.
The carrier particles can be mixed with the toner particles in various suitable combinations. The concentrations are may be from about 1% to about 20% by weight of the toner composition. However, different toner and carrier percentages may be used to achieve a developer composition with desired characteristics.
Imaging
The toners can 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 its 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. These 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 a charging component, an imaging component, a photoconductive component, a developing component, a transfer component, and a fusing component. In embodiments, the development component may include a developer prepared by mixing a carrier with a toner composition described herein. The electrophotographic device may include a high speed printer, a black and white 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 one of the aforementioned methods, the image may then be transferred to an image receiving medium such as paper and the like. In embodiments, the toners may be used in developing an image in an image-developing device utilizing a fuser roll member. Fuser roll members are contact fusing devices that are within the purview of those skilled in the art, in which heat and pressure from the roll may be used to fuse the toner to the image-receiving medium. In embodiments, the fuser member may be heated to a temperature above the fusing temperature of the toner, for example to temperatures of from about 70° C. to about 160° C., in embodiments from about 80° C. to about 150° C., in other embodiments from about 90° C. to about 140° C., after or during melting onto the image receiving substrate.
In accordance with the present disclosure, toners produced with silica as a chelating agent may avoid, low parent particle charge problems that may be present where other chelating agents were used in toner formation. Toners produced in accordance with the present disclosure may possess excellent charging characteristics when exposed to extreme relative humidity (RH) conditions. RH conditions include the high humidity zone (A-zone), which may be about 85% RH at about 28° C., the medium humidity zone (B-zone), which may be about 50% RH at about 21° C., and the low humidity zone (C-zone) which may be about 15% RH at about 10° C.
In embodiments, the toners of the present disclosure may posses a final toner charge (q/d) of from about 2 femtocoulombs per micron (fC/μm) to about 40 fC/μm, in embodiments from about 5 fC/μm to about 30 fC/μm. The toners of the present disclosure may posses a parent toner charge per mass ratio (q/m) of from about 15 microcoulombs per gram (μC/g) to about 100 μC/g, in embodiments from about 30 μC/g to about 95 μC/g.
The following Examples 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. As used herein, “room temperature” refers to a temperature of from about 20° C. to about 25° C.
EXAMPLES
Comparative Example 1
Control cyan toner with ethylene diamine tetraacetic acid (EDTA) was prepared as follows.
A cyan polyester toner was prepared at 2 liter bench scale (150 grams dry theoretical toner). A toner slurry was utilized which included two amorphous polyester resin emulsions (at a ratio of about 50:50). One emulsion included about 109 grams of a low molecular weight resin including an alkoxylated bisphenol A with terephthalic acid, fumaric acid, and dodecenylsuccinic acid co-monomers, and the other emulsion included about 114 grams of a high molecular weight resin including alkoxylated bisphenol A with terephthalic acid, trimellitic acid, and dodecenylsuccinic acid co-monomers. About 2 parts per hundred (pph) of DOWFAXTM 2A1, an alkyldiphenyloxide disulfonate available commercially from The Dow Chemical Company was added to the slurry. Also added thereto was about 30 grams of a crystalline resin emulsion of the following formula:




wherein b was from about 5 to about 2000 and d was from about 5 to about 2000, about 2 pph of DOWFAXTM 2A1, an alkyldiphenyloxide disulfonate available commercially from The Dow Chemical Company, about 53 grams of cyan pigment, in a dispersion, and about 46 grams of a polyethylene wax (from IGI) in a dispersion. The components were mixed and then pH adjusted to 4.2 using 0.3M nitric acid.
The slurry was homogenized for about 5 minutes at from about 3,000 revolutions per minute (rpm) to about 4000 rpm while adding about 2.69 grams of aluminum sulfate as a coagulant and about 36 grams of deionized water (DIW). The toner slurry was then aggregated at about 460 rpm at a temperature of around 45° C. During aggregation, the toner particle size was closely monitored. At around 4.8 microns in size, a shell including the same amorphous emulsion (ratio 50:50) as in the core was added to achieve the final targeted particle size of from about 5.6 to about 5.8 microns. Aggregation continued for about 30 minutes. The pH of the slurry was adjusted to about 7.8 using sodium hydroxide (NaOH), and ethylene diamine tetraacetic acid (EDTA) (commercially available as VERSENE-100 from the Dow Chemical Company) was added to the slurry to freeze, i.e., stop, the aggregation of the toner particles.
The process proceeded with the reactor temperature (Tr) increased to achieve 85° C. Once the Tr reached 85° C., the pH of the toner slurry was reduced to about 7.15 using 0.3M nitric acid to begin the coalescence process. After the toner coalesced to form particles, the toner was cooled.
The toner had a volume average particle diameter of about 5.89 microns, a Volume Average Geometric Size Distribution (GSDv) of about 1.22, a Number Average Geometric Size Distribution (GSDn) of about 1.23, and a circularity of about 0.972. Fine particles, having an average particle diameter from about 1 micron to about 4 microns were present in an amount of about 10.74% of the toner and coarse particles, those having an average particle diameter larger than about 16 microns were present in an amount of about 0.73% of the toner. Residual aluminum on toner particles, as measured by inductively coupled plasma (ICP) was about 71 parts per million (ppm).
Example 1
Cyan toner with colloidal silica was prepared as follows.
A cyan polyester toner was prepared at 2 liter bench scale (150 grams dry theoretical toner). A toner slurry was utilized which included two amorphous polyester resin emulsions (at a ratio of about 50:50). One emulsion included about 109 grams of a low molecular weight resin including an alkoxylated bisphenol A with terephthalic acid, fumaric acid, and dodecenylsuccinic acid co-monomers, and the other emulsion included about 114 grams of a high molecular weight resin including alkoxylated bisphenol A with terephthalic acid, trimellitic acid, and dodecenylsuccinic acid co-monomers. About 2 pph of DOWFAXTM 2A1, an alkyldiphenyloxide disulfonate available commercially from The Dow Chemical Company was added to the slurry. Also added thereto was about 30 grams of a crystalline resin emulsion of the following formula:




wherein b was from about 5 to about 2000 and d was from about 5 to about 2000, about 2 pph of DOWFAXTM 2A1, an alkyldiphenyloxide disulfonate available commercially from The Dow Chemical Company, about 53 grams of cyan pigment, in a dispersion, and about 46 grams of a polyethylene wax (from IGI) in a dispersion. The components were mixed and then pH adjusted to 4.2 using 0.3M nitric acid.
The slurry was homogenized for about 5 minutes at from about 3,000 rpm to about 4000 rpm while adding about 2.69 grams of aluminum sulfate as a coagulant and about 36 grams of DIW. The toner slurry was then aggregated at about 460 rpm at a temperature of around 45° C. During aggregation, the toner particle size was closely monitored. At around 4.8 microns in size, a shell including the same amorphous emulsion (ratio 50:50) as in the core was added to achieve the final targeted particle size of from about 5.6 to about 5.8 microns. Aggregation continued for about 30 minutes. The pH of the slurry was adjusted to about 7.8 using sodium hydroxide (NaOH) and colloidal silica, including a combination of SNOWTEXTM OL and SNOWTEXTM OS available from Nissan Chemical Industries, Ltd., at a ratio of about 1:2, was added to freeze, i.e., stop, the aggregation of toner particles.
The process proceeded with the Tr increased to achieve 85° C. Once the Tr reached 85° C., the pH of the toner slurry was reduced to about 7.15 using 0.3M nitric acid to begin the coalescence process. After the toner coalesced to form particles, the toner was cooled.
The toner had a volume average particle diameter of about 5.95 microns, a GSDv of about 1.24, a GSDn of about 1.24 and a circularity of about 0.957. Fine particles, having an average particle diameter from about 1 micron to about 4 microns, were present in an amount of about 12.01% of the toner, and coarse particles, those having an average particle diameter larger than about 16 microns, were present in an amount of about 0.45% of the toner. Residual aluminum on toner particles, as measured by ICP was about 101 ppm.
Charging
Toner charging. Developers were prepared by adding about 0.5 grams of toners of Comparative Example 1 and Example 1 to 10 grams of Xerox WCP3545 production carrier. Three developer samples were prepared for each toner evaluated. One sample was conditioned overnight in A-zone (28° C./85% relative humidity (RH)), another was conditioned overnight in B-zone (21° C./50% RH), and the other was conditioned overnight in the C-zone (10° C./15% RH). The next day, the developer samples were sealed and agitated for about 2 minutes and then for about 1 hour using a Turbula mixer. After mixing, the triboelectric charge of the toner was measured using a charge spectrograph with a 100 V/cm field. The toner charge (q/d) was measured visually as the midpoint of the toner charge distribution. The charge was reported in millimeters of displacement from the zero line (mm displacement can be converted to femtocoulombs/micron (fC/μm) by multiplying by 0.092). The parent toner charge per mass ratio (q/m) was also measured in micro coulombs per gram (μC/g) using a spectrograph.
Following about 1 hour of mixing, an additional 0.5 grams of toner was added to the already charged developer, and mixed for an additional 15 seconds, where a q/d displacement was again measured, and then mixed for an additional 45 seconds (total 1 minute of mixing), and again a q/d displacement was measured.
Table 1 shows charge characteristics of the toners of Comparative Example 1 and Example 1 in A, B and C-zones. The toner of the Example 1 showed an improvement in parent particle triboelectric charge, which may be attributed to the use of silica.











TABLE 1










B-Zone




A-Zone
parent
C-Zone













Toner ID
q/d
q/m
q/d
q/m
q/d
q/m





Comparative Example 1
7.1
42
15.0
85
14.7
79


Example 1
7.9
46
17.5
91
14.9
89









Fusing

The control cyan toner of Comparative Example 1 and the cyan toner with colloidal silica of Example 1, were submitted for fusing evaluation. Fusing performance (gloss, crease, and hot offset measurements) of particles was collected.
All unfused images were generated using a modified DC12 copier from Xerox Corporation. A TMA (Toner Mass per unit Area) of 1.00 mg/cm2 of each toner was made on Color Xpressions+ paper (90 gsm, uncoated) (sometimes referred to as CX+ paper), using a commercially available fusing fixture. Gloss/crease targets were a square image placed in the center of the page.
Process speed of the fuser was set to 220 mm/second (nip dwell of about 34 miliseconds) and the fuser roll temperature was varied from cold offset to hot offset or up to about 210° C. for gloss and crease measurements.
Crease area measurements were carried out with an image analysis system. Print gloss as a function of fuser roll temperature was measured with a BYK Gardner 75° gloss meter. A summary of the fusing results is reported in Table 2 below. Gloss at 185° C., fusing latitude, and the minimum fusing temperature (MFT) is reported.










TABLE 2







Comparative




Example 1
Example 1


















Cold offset on CX+
120
117


Gloss at MFT on CX+
27.4
21.2


Gloss at 185° C. on CX+
73.5
72.1


Peak Gloss on CX+
74.4
72.2


T(Gloss 50) on CX+
140
146


T(Gloss 60) on CX+
150
158


MFTCA=80 (extrapolated MFT)
123
120


ΔMFT (EA/SA-40° C.) (relative to a
−27
−30


conventional EA toner using the same


resins fused the same day)


Mottle/Hot Offset CX+220 mm/s
>190/>195
<205/<205


Fusing Latitude
>72
>85


ΔFix (TG50 & MFTCA=80)
−25
−19


24 hour @ 60° C. Document Offset
4.50/1.00
4.50/1.50


Toner-Toner/Toner-Paper (rmsLA
0.002/1.4%
 0.002/0.76%


% voide)





CX+ = paper utilized from Xerox Corporation


MFT = minimum fusing temperature


Fusing Latitude = Hot Offset - MFT on CX+ paper


Δfix is the minimum fusing temperature required to reach 50 gloss units or a crease fix area of 80 relative to some control toner.


24-hour @ 60° C. Document Offset Toner = amount of Toner to toner and toner to paper document offset test conducted at 60° C./80 g/cm2/50% R.H.


ΔMFT(EA/SA-40° C.) = minimum fixing temperature in reference to a styrene-acrylate emulsion aggregation type toner


Mottle/Hot Offset = the temperature at which the toner will lift off the paper and stick to the fuser roll


T(Gloss 50) = temperature at which the toner reaches 50 gloss units


T(Gloss 60) = temperature at which the toner reaches 60 gloss units






FIGS. 1 and 2 are graphs depicting image gloss and crease area, respectively, as a function of fusing temperature of the cyan toner of Example 1 produced with colloidal silica in accordance with the present disclosure, compared with the control cyan toner of Comparative Example 1 lacking the silica treatment used as a control. As seen from the data of Tables 1 and 2 above and the graphs of FIGS. 1 and 2, neither charging nor fusing showed significant difference due to the presence of silica.
It will be appreciated that variations 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.

## Claims

1. A process comprising:
contacting at least one polyester resin with at least one surfactant and an aggregating agent comprising a cation to form a mixture;
aggregating the mixture with an aggregating agent comprising a cation to form particles;
then contacting the mixture with colloidal silica, wherein the colloidal silica is added as a chelating agent;
adjusting the pH of the mixture comprising colloidal silica;
coalescing the particles to form toner particles; and
recovering the toner particles.

2. The process of claim 1, wherein the at least one polyester resin comprises at least one amorphous polyester resin including alkoxylated bisphenol A fumarate/terephthalate based polyester or copolyester resin, optionally in combination with at least one crystalline polyester resin of the formula




wherein b is from about 5 to about 2000 and d is from about 5 to about 2000.

3. The process of claim 1, wherein aggregating the mixture occurs at a temperature of from about 40 ° C. to about 100° C., for a time of from about 0.5 hours to about 6 hours.

4. The process of claim 1, wherein coalescing the particles occurs at a temperature of from about 45° C. to about 100 ° C., over a period of time from about 0.01 to about 9 hours.

5. The process of claim 1, wherein the colloidal silica is used in lieu of ethylene diamine tetraacetic acid (EDTA).

6. The process of claim 1, wherein the colloidal silica has a solids content from about 1% to about 40% and particles with a volume average particle size from about 1 nm to about 100 nm.

7. The process of claim 1, wherein colloidal silica is present from about 1% to about 15% by weight of the at least one polylester resin.

8. The process of claim 1, wherein the toner particles possess a parent toner charge per mass ratio of from about 15 to about 100 microcoulombs per gram.

9. A process comprising:
contacting at least one amorphous polyester resin with at least one crystalline polyester resin and an aggregating agent comprising a cation in a mixture;
aggregating the mixture with an aggregating agent comprising a cation to form particles;
then contacting the mixture with colloidal silica, wherein the colloidal silica is added as a chelating agent;
adjusting the pH of the mixture comprising colloidal silica with a basic solution;
coalescing the particles to form toner particles; and
recovering the toner particles.

10. The process of claim 9, wherein the at least one amorphous polyester resin comprises an alkoxylated bisphenol A fumarate/terephthalate based polyester or copolyester resin, and wherein the at least one crystalline polyester resin comprises




wherein b as from about 5 to about 2000 and d is from about 5 to about 2000.

11. The process of claim 9, wherein aggregating the mixture occurs at a temperature of from about 40° C. to about 100 ° C., for a time of from about 0.5 hours to about 6 hours.

12. The process of claim 9, wherein coalescing the particles occurs at a temperature of from about 45° C to about 100 ° C., over a period of time from about 0.01 to about 9 hours.

13. The process of claim 9, wherein the colloidal silica has a solids content from about to about 1% to about 40% and particles with a volume average particle size from about 1 nm to about 100 nm.

14. The process of claim 9, wherein the colloidal silica is present from about 1% to about 15% by weight of the at least one amorphous polyester resin and the at least one crystalline polyester resin.

15. The process of claim 9, wherein the toner particles possess a parent toner charge per mass ratio of from about 15 to about 100 microcoulombs per gram.

16. A process comprising:
contacting at least one amorphous polyester resin with at least one crystalline polyester resin and an aggregating agent comprising a cation in a mixture;
aggregating the mixture with an aggregating agent comprising a cation to form particles;
then contacting the mixture with colloidal silica, wherein the colloidal silica is added as a chelating agent;
stopping aggregation of the particles by adjusting the pH of the mixture comprising colloidal silica to from about 3 to about 10;
coalescing the particles to from toner particles; and
recovering the toner particles.

17. The process of claim 16, wherein the at least one amorphous polyester resin comprises an alkoxylated bisphenol A fumarate/terephthalate based polyester or copolyester resin; and wherein the at least one crystalline polyester resin comprises




wherein b is from about 5 to about 2000 and d is from about 5 to about 2000.

18. The process of claim 16, wherein the silica comprises colloidal silica having a solids content from about 1 % to about 40% and particles having a volume average particle size from about 1 nm to about 100 nm.

19. The process of claim 1 wherein the toner particles possess a parent toner charge per mass ratio of from about 15 to about 100 microcoulombs per gram.

20. ended The process or claim 16, wherein the colloidal silica is present from about 1% to about 15% by weight of the at least one amorphous polyester resin and the at least one crystalline polyester resin.