Toner processes

Abstract

A process for the preparation of toner involving (i) aggregating a colorant dispersion containing a suitable surfactant with a latex emulsion containing an anionic surfactant, a nonionic surfactant, and a water miscible chain transfer agent, or a nonionic surfactant with chain transfer characteristics to form toner sized aggregates; (ii) coalescing or fusing said aggregates; and optionally (iii) isolating, washing, and drying the resulting toner.

What is claimed is:  
     
         1 . A process for the preparation of toner comprising 
 (i) aggregating a colorant dispersion containing a suitable surfactant with a latex emulsion containing an anionic surfactant, a nonionic surfactant, and a water miscible chain transfer agent, or a nonionic surfactant with chain transfer characteristics to form toner sized aggregates;    (ii) coalescing or fusing said aggregates; and optionally    (iii) isolating, washing, and drying the resulting toner.    
     
     
         2 . A process in accordance with  claim 1  wherein said aggregating is below about the glass transition temperature of the polymer present in the latex emulsion; the coalescing or fusing of said aggregates is above about the polymer glass transition temperature; and there results toner with a size of from about 2 to about 20 microns in volume average diameter, and isolating, washing, and drying are accomplished.  
     
     
         3 . A process in accordance with  claim 2  wherein said temperature below the glass transition temperature is from about 25° C. to about 60° C., and said heating above the glass transition temperature is from about 60° C. to about 100° C.  
     
     
         4 . A process in accordance with  claim 2  wherein said temperature below the glass transition temperature is from about 35° C. to about 55° C., and said heating above the glass transition temperature is from about 70° C. to about 95° C.  
     
     
         5 . A process in accordance with  claim 1  wherein the temperature at which said aggregating is accomplished controls the size of the aggregates, and wherein the final toner size is from about 2 to about 10 microns in volume average diameter, and wherein the temperature and time of said coalescing of the components of aggregates control the shape of the resultant toner, and wherein there is accomplished the isolating, washing, and drying of said toner product.  
     
     
         6 . A process in accordance with  claim 1  wherein the aggregating is accomplished at a temperature of from about 45°C. to about 55° C., and wherein the coalescing is accomplished at a temperature of from about 85° C. to about 95° C.  
     
     
         7 . A process in accordance with  claim 1  wherein said water miscible chain transfer agent is selected in an amount of from about 0.5 to about 10 weight percent based on the amount of polymer resin contained in said latex.  
     
     
         8 . A process in accordance with  claim 1  wherein said water miscible chain transfer agent is an acid, an alcohol, an ether, an amine, an amide, a ketone, an aldehyde, or a carboxylic ester.  
     
     
         9 . A process in accordance with  claim 8  wherein the alcohol is methanol, ethanol, propanol, butanol, ethylene glycol, or glycerol; the acid is formic acid, acetic acid, propionic acid, butanoic acid, or succinic acid; the amine is methylamine, ethylamine, propylamine, butylamine, diethylamine, or trimethylamine; the ether is methyl ether, ethyl ether, propyl ether, butyl ether, tetrahydrofuran, or trioxane; the amide is acetamide or propanamide; the ketone is acetone, butanone, or pentanone; the aldehyde is formaldehyde, acetaldehyde, propanal, or butanal; and the carboxylic ester is methyl formate, ethyl formate, or methyl acetate.  
     
     
         10 . A process in accordance with  claim 8  wherein the alcohol is isopropanol or n-butanol, the acid is acetic acid, the amine is trimethylamine, the ether is ethyl ether or tetrahydrofuran, the ketone is acetone, the aldehyde is formaldehyde, and the ester is ethyl formate.  
     
     
         11 . A process in accordance with  claim 8  wherein the chain transfer agent is isopropanol, n-butanol, or tetrahydrofuran, each present in effective amounts; for isopropanol from about 0.5 to about 3 percent by weight of the polymer resin of the latex; for n-butanol from 0.5 to 3 percent by weight of the polymer resin; and for tetrahydrofuran from about 0.5 to about 2 percent by weight of the polymer resin.  
     
     
         12 . A process in accordance with  claim 1  wherein said nonionic surfactant with chain transfer characteristics is an adduct of ethylene oxide and dodecyl mercaptan.  
     
     
         13 . A process in accordance with  claim 12  wherein said adduct is a polyethylene tertiary thioether, a polyethylene thioester, or an ethoxylated thiol.  
     
     
         14 . A process in accordance with  claim 1  wherein said nonionic surfactant with chain transfer characteristics is a polyethylene tertiary thioether of the formula C 11 H 25 C—S—CH 2 —O—(CH 2 CH 2 O) n H wherein n represents the number of segments, and is a number of from about 10 to about 40; ethoxylated dodecyl mercaptan with the formula HS—C 11 H 22 —O(CH 2 CH 2 O) m H wherein m is a number of from about 20 to about 50; polyethylene thioesters of the formula CH 3 —O—(CH 2 CH 2 O) k —COOCH 2 —SH wherein k is from about 10 to about 40, and wherein each surfactant is present in an amount of from about 0.1 to about 10 percent by weight of the monomers selected for the preparation of the latex polymer.  
     
     
         15 . A process in accordance with  claim 1  wherein said nonionic surfactant with chain transfer characteristics is covalently bonded to the surface of the latex.  
     
     
         16 . A process in accordance with  claim 1  wherein there is selected for the latex a second chain transfer agent.  
     
     
         17 . A process in accordance with  claim 16  wherein said second transfer agent is dodecanethiol, and is selected in an amount of from about 0.1 to about 10 percent by weight of the latex polymer, or latex resin.  
     
     
         18 . A process in accordance with  claim 1  wherein the colorant is a pigment, and wherein said pigment dispersion contains an ionic surfactant, and the latex emulsion contains a nonionic surfactant and an ionic surfactant of opposite charge polarity to that of ionic surfactant present in said pigment dispersion.  
     
     
         19 . A process in accordance with  claim 1  wherein there is selected a cationic surfactant for the colorant dispersion, and there is an ionic surfactant present in the latex mixture, and which surfactant is an anionic surfactant.  
     
     
         20 . A process in accordance with  claim 1  wherein the aggregating is conducted at a temperature of from about 15° C. to about 1° C. below the Tg of the latex resin for a duration of from about 0.5 hour to about 3 hours, and wherein the coalescing of the components of aggregates for the formation of integral toner particles comprised of colorant and resin is accomplished at a temperature of about 85° C. to about 95° C. for a duration of from about 1 hour to about 5 hours.  
     
     
         21 . A process in accordance with  claim 1  wherein the latex contains a polymer or resin selected from the group consisting of poly(styrene-alkyl acrylate), poly(styrene-1,3-diene), poly(styrene-alkyl methacrylate), poly(styrene-alkyl acrylate-acrylic acid), poly(styrene-1,3-diene-acrylic acid), poly(styrene-alkyl methacrylate-acrylic acid), poly(alkyl methacrylate-alkyl acrylate), poly(alkyl methacrylate-aryl acrylate), poly(aryl methacrylate-alkyl acrylate), poly(alkyl methacrylate-acrylic acid), poly(styrene-alkyl acrylate-acrylonitrile-acrylic acid), poly(styrene-1,3-dieneacrylonitrile-acrylic acid), and poly(alkyl acrylate-acrylonitrile-acrylic acid), wherein said resin is present in an amount of about 80 percent by weight to about 98 percent by weight of toner, wherein said colorant is a pigment.  
     
     
         22 . A process in accordance with  claim 1  wherein the latex contains a resin selected from the group consisting of poly(styrenebutadiene), poly(methylstyrene-butadiene), poly(methyl methacrylatebutadiene), poly(ethyl methacrylate-butadiene), poly(propyl methacrylatebutadiene), poly(butyl methacrylate-butadiene), poly(methyl acrylatebutadiene), poly(ethyl acrylate-butadiene), poly(propyl acrylate-butadiene), poly(butyl acrylate-butadiene), poly(styrene-isoprene), poly(methylstyreneisoprene), poly(methyl methacrylate-isoprene), poly(ethyl methacrylateisoprene), poly(propyl methacrylate-isoprene), poly(butyl methacrylateisoprene), poly(methyl acrylate-isoprene), poly(ethyl acrylate-isoprene), poly(propyl acrylate-isoprene), and poly(butyl acrylate-isoprene); poly(styrene-propyl acrylate), poly(styrene-butyl acrylate), poly(styrenebutadiene-acrylic acid), poly(styrene-butadiene-methacrylic acid), poly(styrene-butadiene-acrylonitrile-acrylic acid), poly(styrene-butyl acrylateacrylic acid), poly(styrene-butyl acrylate-methacrylic acid), poly(styrene-butyl acrylate-acrylononitrile), and poly(styrene-butyl acrylate-acrylononitrile-acrylic acid).  
     
     
         23 . A process in accordance with  claim 1  wherein the anionic surfactant is selected from the group consisting of sodium dodecyl sulfate, sodium dodecylbenzene sulfate and sodium dodecylnaphthalene sulfate, and wherein the cationic surfactant is a quaternary ammonium salt.  
     
     
         24 . A process in accordance with  claim 1  wherein the colorant is carbon black, magnetite, cyan, yellow, magenta, or mixtures thereof.  
     
     
         25 . A process in accordance with  claim 1  wherein the toner particles isolated are from about 2 to about 10 microns in average volume diameter, and the particle size distribution thereof is from about 1.15 to about 1.30, wherein each of the surfactants utilized represents from about 0.01 to about 5 weight percent of the total reaction mixture, wherein there is added to the surface of the formed toner metal salts, metal salts of fatty acids, silicas, metal oxides, or mixtures thereof, each in an amount of from about 0.1 to about 10 weight percent of the obtained toner particles, and wherein washing and drying are accomplished.  
     
     
         26 . A process for the preparation of toner comprising 
 (i) aggregating a colorant dispersion and a latex emulsion containing a water miscible chain transfer agent; and    (ii) coalescing the aggregates formed.    
     
     
         27 . A process in accordance with  claim 26  wherein suitable surfactants are selected for the colorant dispersion and the latex emulsion, wherein aggregating is accomplished by heating below about the glass transition temperature of the latex resin; coalescing is accomplished by heating above about the glass transition temperature of the latex resin; and subsequent to (ii) the toner product is isolated and washed to remove surfactants.