Toner compositions

#The present invention is generally directed to toner compositions and processes thereof, and more specifically, the present invention relates to a toner comprised of a sulfonated polyester resin, and colorant, and wherein the toner, especially the surface thereof, is comprised of tetra-alkylated quatemary ammonium salts or tetra-alkylated quatemary phosphonium salts of sulfonated polyester groups bound or attached on the toner surface. More specifically, the present invention is directed to toner compositions and processes thereof, wherein the surface layer of the toner is comprised of a linear sulfonated polyester resin, rendered hydrophobic by a wet chemical surface treatment with aqueous solutions of various quatemary ammonium and/or phosphonium salts thereby, for example, enhancing the surface charging performance of the toner particles enabling high triboelectric charge levels at 20 percent RH (Relative Humidity), and 80 percent RH in the range of from about -30 to about -90 microcoulombs per gram, and about -20 to about -40 microcoulombs per gram, respectively; a low relative humidity sensitivity, such as from about 1.1 to about 2.8; and low melt fusing and high gloss properties. Furthermore, the present invention relates to the coalescence or fusion of colorant and resin particles, especially colloidal particles comprised of a sodio-sulfonated linear polyester dissipated in water, of average polyester particle size for example, of from about 5 to about 80 nanometers, and preferably from about 10 to about 40 nanometers as determined by a Nicomp particle sizer. In embodiments, the present invention is directed to the economical in situ, chemical or direct preparation of toners comprised of a sulfonated polyester resin, colorant, and a toner surface layer comprised of ionic complexes formed between the anionic sulfonate groups of the polyester resin and quaternary ammonium and/or phosphonium cations, reference Formula 1 herein, and wherein the alkyl substituents of such ions can include (i) C1 to C18 alkyl groups such as methyl, ethyl, propyl, butyl, decyl, stearyl and the like; (ii) C6 to C18 aryl substituents, such as phenyl, naphthyl, phenanthryl, anthracenyl, fluorenyl and the like; (iii) aryl-alkyl substituents of the general formula C.sub.6 H.sub.5 (CH.sub.2).sub.n -- containing both an aryl group and methylene spacer groups such as (CH.sub.2).sub.n, where n=0 to 5, such as phenyl, benzyl, 2-phenylethyl, 3-phenylpropyl and the like. ##STR1## wherein A is a toner of a sulfonated polyester and colorant; G is nitrogen or phosphorus, and where R.sub.1, R.sub.2, R.sub.3, R.sub.4 are each independently alkyl, such as CH.sub.3 (CH.sub.2).sub.n --; wherein n represents the number of segments or groups, and is, for example, a number of from 0 to about 20; or wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 is C.sub.6 H.sub.5 (CH.sub.2).sub.n wherein n represents the number of segments, and is, for example, from 1 to about 5, or wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 are aryl; X is a halide (F, Cl, Br, I), acetate CH.sub.3 CO.sub.2.sup.-, HSO.sub.4.sup.-, or H.sub.2 PO.sub.4.sup.- ; and M.sup.n+ is a metal ion such as Na.sup.+, Zn.sup.2+, Al.sup.3+, Mg.sup.2+, Ca.sup.2+, Cu.sup.2+, Ba.sup.2+, and the like.

#In a specific embodiment of the present invention there is provided a toner composition comprised of (i) a sulfonated polyester core, obtained, for example, by the coalescence of a colorant and a colloidal aqueous solution comprised of about 10 to about 20 percent solids of sodio-sulfonated polyester resin particles, generated with a coalescence agent comprised of, for example, the halide (fluoride, chloride, bromide, iodide), acetate, sulfate, phosphate or alkylate salt of divalent Group II elements, such as magnesium, calcium, beryllium, barium, or the analogous salts of the transition metals of Groups III to XII, such as for example zinc, copper, cadmium, manganese, vanadium, iron, cobalt, chromium, niobium, zirconium, nickel and the like; and (ii) a surface layer of sulfonated (or sodio-sulfonated) polyester which is chemically treated with a heated aqueous solution of tetra-alkylated quatemary ammonium and/or phosphonium halide (fluoride, chloride, bromide, iodide), acetate, sulfate, phosphate, or alkylate salt, such that the final concentration of the quatemary ammonium and/or phosphonium salt is in the range amount of from about 0.1 to about 5.0 weight percent of toner solids, and typically is in the range amount of about 1.0 to about 3.0 weight percent of toner solids. The aforementioned in situ surface treatment selectively targets and directs the hydrophilic and RH sensitive metal-complexed sulfonate groups to the toner surface by causing an ion exchange of the complexed metal ion, which can be an alkali metal ion from Group I, for example lithium, sodium, potassium and the like, alkaline earth metal ion from Group II, for example magnesium, calcium, beryllium, the barium salts of chloride, bromide, iodide, acetate, or alkylate, or any transition metal ion of Groups III to XII, for example zinc, copper, cadmium, manganese, vanadium, iron, cobalt, chromium, niobium, zirconium, nickel and the like, for a quatemary ammonium or phosphonium ion thereby, for example, rendering the toner surface more hydrophobic and less hygroscopic. The resulting surface treated toner particles display in embodiments enhanced triboelectric charging levels, especially in the higher 80 percent relative humidity zone, and lower RH sensitivity of charging performance between the 20 percent relative humidity zone and 80 percent relative humidity zone without compromising the low-melt toner fusing properties, and with toner minimum fusing temperatures of from about 125.degree. C. to about 140.degree. C. determined at a crease area of about 60 units, and high gloss characteristics with peak gloss levels in the range of from about 40 to about 70 gloss units, as measured with a Gardner gloss meter, when compared to the nonsurface treated toners of the same composition. In embodiments, the toner composites or compositions of the present invention display: (i) an average volume diameter of, for example, from about 1 to about 25, and preferably from 1 to about 10 microns and a narrow GSD of, for example, from about 1.16 to about 1.26 or about 1.18 to about 1.28 as measured on the Coulter Counter; (ii) a particle morphology which is nearly spherical in shape; (iii) high triboelectric charge levels at 20 percent RH and 80 percent RH in the range of from about -30 to about -90 microcoulombs per gram, and about -20 to about -40 microcoulombs per gram, respectively, as compared with the same nonsurface treated toner; (iv) lower RH sensitivity, as expressed in the 20 percent RH to 80 percent RH ratio of charge-to-mass values, of from about 1.3 to 3, when compared to a treated toner; (v) low fusing temperatures, for example, of from about 110.degree. C. to about 145.degree. C., corresponding to a crease area of 60 units; (vi) high gloss levels of a fused image, for example, of from about 60 to 70 gloss units, as measured on a Gardner gloss meter; and (vii) low or no vinyl offset, of from about 0.03 to about 0.11 percent, measured as the percentage of toner mass from a fused image transferred onto a MYLAR.RTM. sheet over a period of 48 hours at 50.degree. C. The process of the present invention in embodiments enables the utilization of polymers obtained by polycondensation reactions, such polymers including, for example, polyesters, and more specifically, the sulfonated polyesters as illustrated in U.S. Pat. Nos. 5,348,832; 5,658,704 and 5,604,076, the disclosures of which are totally incorporated herein by reference, and which polyesters may be selected for low melting toners.

#The toners of the present invention can be selected for known electrophotographic imaging methods, printing processes, including color processes, digital methods, and lithography.

#The following Examples are being submitted to further define various species of the present invention. These Examples are intended to be illustrative only and are not intended to limit the scope of the present invention. Also, parts and percentages are by weight unless otherwise indicated.

#Preparation Of Sodio Sulfonated Polyesters:

#A linear sulfonated random copolyester resin comprised of, on a mol percent, 0.465 of terephthalate, 0.035 of sodium sulfoisophthalate, 0.475 of 1,2-propanediol, and 0.025 of diethylene glycol was prepared as follows. In a 5 gallon Parr reactor equipped with a bottom drain valve, double turbine agitator, and distillation receiver with a cold water condenser were charged 3.98 kilograms of dimethylterephthalate, 451 grams of sodium dimethyl sulfoisophthalate, 3.104 kilograms of 1,2-propanediol (1 mole excess of glycol), 351 grams of diethylene glycol (1 mole excess of glycol), and 8 grams of butyltin hydroxide oxide catalyst. The reactor was then heated to 165.degree. C. with stirring for 3 hours whereby 1.33 kilograms of distillate were collected in the distillation receiver, and which distillate was comprised of about 98 percent by volume of methanol and 2 percent by volume of 1,2-propanediol as measured by the ABBE refractometer available from American Optical Corporation. The reactor mixture was then heated to 190.degree. C. over a one hour period, after which the pressure was slowly reduced from atmospheric pressure to about 260 Torr over a one hour period, and then reduced to 5 Torr over a two hour period with the collection of approximately 470 grams of distillate in the distillation receiver, and which distillate was comprised of approximately 97 percent by volume of 1,2-propanediol and 3 percent by volume of methanol as measured by the ABBE refractometer. The pressure was then further reduced to about 1 Torr over a 30 minute period whereby an additional 530 grams of 1,2-propanediol were collected. The reactor was then purged with nitrogen to atmospheric pressure, and the polymer product discharged through the bottom drain onto a container cooled with dry ice to yield 5.60 kilograms of 3.5 mol percent sulfonated polyester resin, sodio salt of (1,2-propylene-dipropylene-5-sulfoisophthalate)-copoly (1,2-propylene-dipropylene terephthalate). The sulfonated polyester resin glass transition temperature was measured to be 56.6.degree. C. (onset) utilizing the 910 Differential Scanning Calorimeter available from E.I. DuPont operating at a heating rate of 10.degree. C. per minute. The number average molecular weight was measured to be 3,250 grams per mole, and the weight average molecular weight was measured to be 5,290 grams per mole using tetrahydrofuran as the solvent.