Title of Invention

"METHOD FOR PREPARING AQUEOUS DISPERSIONS OF POLYMER PARTICLES"

Abstract

The invention provides a method for preparing an aqueous dispersion of polymer particles comprising the following steps: (i) preparing a dispersion having a continuous aqueous phase, a dispersed organic phase comprising one or more ethylenically unsaturated monomers, and an amphiphilic RAFT agent as a stabiliser for said organic phase, and (ii) polymerising said one or more ethylenically unsaturated monomers under the control of said amphiphilic RAFT agent to form said aqueous dispersion of polymer particles, novel amphiphilic RAFT agents for use in this method, novel RAFT agents useful in making these amphiphilic RAFT agents and methods for their manufacture.

Full Text

FIELD OF THE INVENTION The present invention relates to method for preparing aqueous dispersions of polymer particles. This invention relates to aqueous dispersions of polymer particles, and in particular to a method of preparing aqueous dispersions of polymer particles using amphiphilic chain transfer agents. The invention also relates to novel amphiphilic chain transfer agents, methods for their preparation and chain transfer agents useful in the preparation of such amphiphilic chain transfer agents. BACKGROUND OF THE INVENTION Emulsion polymerisation provides one of the most effective means of preparing an aqueous dispersion of polymer particles. Accordingly, this polymerisation technique has been extensively adopted by industry to manufacture aqueous dispersions suited for use in products such as paints, adhesives, fillers, primers and sealants. The conventional emulsion polymerisation system initially comprises water, monomer, surfactant and initiator. The emulsion polymerisation process generally commences by dispersing monomer (organic phase) in the water (aqueous phase), with the aid of the surfactant, to provide an emulsion. The initiator, which is usually dissolved in the continuous aqueous phase, provides a source of the free radicals that initiate polymerisation. The dispersed organic phase provides monomer to the propagating polymer chains which in turn form small polymer particles. During formation and in a final form, the polymer particles are stabilised from coalescence by the surfactant. The polymerisation process therefore provides as a product an aqueous dispersion of polymer particles. Although very useful in providing aqueous dispersions of polymer particles for Most preferred amphiphilic RAFT agents include, but are not limited to, the following compounds: (Formula Removed) where R3; X and n are as previously defined. Most preferred RAFT agents include, but are not limited to, the following formulas (15-21): (Formula Removed) We claim: 1. A method for preparing an aqueous dispersion of polymer particles comprising the following steps: (i) preparing a dispersion having a continuous aqueous phase, a dispersed organic phase comprising one or more ethylenically unsaturated monomers, and an amphiphilic RAFT agent as a stabiliser for said organic phase, and (ii) polymerising said one or more ethylenically unsaturated monomers under the control of said amphiphilic RAFT agent to form said aqueous dispersion of polymer particles. 2. The method as claimed in claim 1, wherein the dispersion of step (i) is prepared by forming a solution of amphiphilic RAFT agent in water and polymerising added ethylenically unsaturated monomer under the control of the amphiphilic RAFT agent. 3. The method as claimed in claim 1, wherein the dispersion of step (i) is prepared by forming a composition comprising water insoluble amphiphilic RAFT agent and ethylenically unsaturated monomer, and combining this composition with water. 4. The method as claimed in claim 3, wherein the RAFT agent is dissolved in monomer, optionally together with organic solvent. 5. The method as claimed in claim 1, wherein the dispersion of step (i) is prepared by forming a composition comprising water insoluble amphiphilic RAFT agent and water, and combining this composition with ethylenically unsaturated monomer. 6. The method as claimed in any one of claims 1 to 5, wherein the amphiphilic RAFT agent is of general formula (4): (Formula Removed) where each X is independently a polymerised residue of an ethylenically unsaturated monomer, n is an integer ranging from 0 to 100, R1 is an organic group optionally substituted with one or more hydrophilic groups and Z is any group that can promote sufficient reactivity of the thiocarbonyl group towards radical addition while not slowing the rate of fragmentation to the extent that there is unacceptable retardation of polymerisation. 7. The method as claimed in claim 6, wherein R1 is selected from C1-C6 alkyl, C1-C6 alkoxy aryl or heteroaryl, each of which is substituted with one or more hydrophilic groups selected from -CO2H, -CO2R', -SO3H, -OSO3H, -SOR', -SO2R', -OP(OH)2, -P(OH)2, -PO(OH)2, -OH, -OR', -(OCH2-CHR)w-OH, -CONH2, CONHR', CONR'R", -NR'R", -N+R'R"R"', where R is selected from C1-C6 alkyl, w is 1 to 10, R', R" and R'" are independently selected from alkyl and aryl which are optionally substituted with one or more hydrophilic substituents selected from -CO2H, -SO3H, -OSO3H, -OH, -(COCH2CHR)w-OH, -CONH2, -SOR and SO2R, and salts thereof, and wherein Z is selected from optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted arylalkyl, optionally substituted alkylthio, optionally substituted arylalkylthio, dialkoxy- or diaryloxy- phosphinyl [-P(=O)OR22], dialkyl- or diaryl- phosphinyl [-P(=O)R22], optionally substituted acylamino, optionally substituted acylimino, optionally substituted amino, R1-(X)n-S- and a polymer chain formed by any mechanism; wherein R1; X and n are as defined herein or in claim 6, and R2 is selected from the group consisting of optionally substituted C1-C18 alkyl, optionally substituted C2-C18 alkenyl, optionally substituted aryl, optionally substituted heterocyclyl, optionally substituted aralkyl, optionally substituted alkaryl. 8. The method as claimed in any one of claims 1 to 5, wherein the amphiphilic RAFT agent is of general formula (4): (Formula Removed) wherein X, n and Z are as defined in claim 6 and wherein R1 is an organic group substituted with one or more hydrophobic groups. 9. A method of preparing a paint, filler, adhesive, primer or sealant comprising preparing a dispersion as claimed in any one of claims 1 to 8, and combining the dispersion with one or more formulation components. 10. A paint, filler, adhesive, primer or sealant comprising a dispersion of polymer particles prepared in accordance with the method as claimed in any one of claims 1 to 8.

Documents:

1980-DELNP-2004-Claims-(26-08-2011).pdf

1980-DELNP-2004-Correspondence Others-(26-08-2011).pdf

1980-delnp-2004-Correspondence-Others-(25-04-2011).pdf

1980-DELNP-2004-Description (Complete)-(26-08-2011).pdf

1980-DELNP-2004-Form-1-(26-08-2011).pdf

1980-DELNP-2004-Form-13-(26-08-2011).pdf

1980-DELNP-2004-Form-2-(26-08-2011).pdf

1980-delnp-2004-Form-3-(25-04-2011).pdf

1980-DELNP-2004-GPA-(26-08-2011).pdf