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INSITU CARBOXYLIC ACID POLYMER EMULSIONS FOR EMULSION/AGGREGATION TONERS

IP.com Disclosure Number: IPCOM000027544D
Original Publication Date: 1997-Aug-31
Included in the Prior Art Database: 2004-Apr-08
Document File: 4 page(s) / 202K

Publishing Venue

Xerox Disclosure Journal

Abstract

Disclosed are method for preparing toners by emulsiodaggregation techniques which permit control of the surface chemistry and properties of the resulting latex particles. In one approach, by controlling the feed rates of various monomers into the emulsion polymerization reactor, the proportion of acrylic acid at the particle surface can be increased. In another approach, polyacrylic acid, which act as a stabilizer, is preformed in the reactor prior to the addition of other monomers. Both approaches are useful in controlling the surface and physical properties of the resulting toner particles. An additional advantage of the methods is the ability to reduce the need for extensive washing of the resulting particles to remove unwanted surfactant.

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XEROX DISCLOSURE JOURNAL

INSITU CARBOXYLIC ACID Proposed Classification POLYMER EMULSIONS FOR
EMULSION/AGGREGATION TONERS
Garland J. Nichols
Chieh-Min Cheng

U. S. C1.430/106 Int. C1. G03g 09/08

Disclosed are method for preparing toners by emulsiodaggregation techniques which permit control of the surface chemistry and properties of the resulting latex particles. In one approach, by controlling the feed rates of various monomers into the emulsion polymerization reactor, the proportion of acrylic acid at the particle surface can be increased. In another approach, polyacrylic acid, which act as a stabilizer, is preformed in the reactor prior to the addition of other monomers. Both approaches are useful in controlling the surface and physical properties of the resulting toner particles. An additional advantage of the methods is the ability to reduce the need for extensive washing of the resulting particles to remove unwanted surfactant.

In emulsion/aggregation particle forming processes, toner can be prepared by, for example, aggregating and coalescing a pigment and latex particles. Aggregation and coalescence steps are critical steps in the process and allow for particles of desired shape, size, stability, and performance. When CBr4 was used as the chain transfer agent to control the aqueous phase termination of oligomers containing acrylic acid units there were provided robust aggregates. The resulting aggregates did adhere to one another during coalescence, even with the addition of stabilizers to aid in fixing the aggregates to a desired size. The methods increase polymer chain termination and thereby reduce the amount of grafted acrylic acid. The present process yields acrylic acid containing copolymer surface active material that aids in the particle aggregation step. Illustrative examples follow.

Two Phase Aaueous Polymer ComDosition

A two-phase acidic aqueous polymer composition was prepared by a stepwise emulsion polymerization process. In a 500 ml glass flask with a stirrer set at 200 rpm, 210 grams of styrene, 70 grams of n-butyl acrylate, and 7 grams of 1-dodecanethiol were mixed with 1,020 grams of deionized water in which 2 grams of ammonium persulfate, 13.3 grams of DOWFAX 2A1 (47% aqueous sodium tetrapropyl diphenyloxide disulfonate, from Dow Chemical) and 3.2 grams of Triton X-100 (octylphenoxy polyethoxy ethanol, from Union Carbide) were dissolved. This solution was purged with nitrogen for 60 minutes, then the

XEROX DISCLOSURE JOURNAL - Vol. 22, NO. 4 July/August 1997 223

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INSITU CARBOXYLIC ACID POLYMER EMULSIONS FOR EMULSION/AG- GREGATION TONERS (CONT'D)

temperature was raised from 25°C to 80°C at a rate of l"C/min. Once the reaction tem- perature reached 70"C, an acidic solution prepared from 8.4 grams of acrylic acid, 2 grams of ammonium persulfate and 100 grams of deionized water was added over 20 min. The emulsion and the aqueous phase polymers...