Patent EP0030439A2 successfully refreshed from Google Patents.
EP0030439A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Polymerisation process for preparation of non-aqueous dispersions of microparticles and coating compositions containing said microparticles
Assignee: Imperial Chemical Industries Ltd
•
Filing: 1980-12-01
•
Granted: —
•
Expires: 2000-12-01
Abstract
Abstract A process is described for making sterically stabilised non-aqueous dispersions of composite polymer microparticles, in which (1) monomers including at least one crosslinking monomer are polymerised in an aqueous medium at a temperature at least 10° higher than the glass transition temperature of the polymer to be formed, in the presence of a block or graft copolymer stabilising agent, under conditions such that there is at no time present a separate monomer phase, (2) further monomers, not including any crosslinking monomer, are polymerised in the dispersion thus obtained, the presence of a separate monomer phase again being avoided, and (3) the microparticles are transferred from the resulting dispersion into a non-aqueous medium which is a solvent for the non-cross- linked polymer generated in (2). The microparticles are of value for incorporation into coating compositions the main film-forming constituent of which is compatible with the non-cross- linked component of the particles.
Inventors
- 👤 Alan James Backhouse
- 👤 Charles Bromley
- 👤 Morice William Thompson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-27 20:59
CPC Classifications
C; C08; C08J; C08J3/00; C08J3/02; C08J3/09; C08F; C08F265/00; C08F265/04; C08F265/06; C08F291/00; Y; Y10; Y10S; Y10S525/00; Y10S525/902
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
318 words
A process for the production of a stable dispersion in a non-aqueous liquid medium of composite polymer microparticles having a diameter of from 0.1 to 10 microns, each of which comprises a core of crosslinked polymer surrounded by and grafted to a layer of non-crosslinked polymer, the process comprising the steps of (1) polymerising one or more ethylenically unsaturated monomers, including at least one crosslinking monomer, from which the crosslinked core polymer of the microparticles is to be derived, in an aqueous medium as hereinbefore defined at a temperature at least 10°C higher than the glass transition temperature of the core polymer in the presence in the aqueous medium as steric stabiliser of a block or graft copolymer which contains in the molecule a polymeric component which is solvatable by the aqueous medium and another polymeric component which is not solvatable by the aqueous medium and is capable of becoming associated with the polymer particles formed, the concentration of free monomer in the polymerisation mixture being maintained throughout this process step at a level such that at no time does the free monomer form a separate phase and the total amount of monomer polymerised being such that the resulting dispersion contains at least 20% by weight of microparticles, (2) polymerising, in the dispersion obtained from step (1), one or more further ethylenically unsaturated monomers, not including any crosslinking monomer, from which the non-crosslinked polymer of the outer layer is to be derived, optionally in the presence of additional block or graft copolymer stabiliser, the concentration of such further monomer in the free state in the polymerisation mixture being maintained at a level such that at no time does that free monomer form a separate phase, and (3) transferring the polymer microparticles from the resulting dispersion into a non-aqueous liquid medium which is a solvent for the non-crosslinkable polymer under such conditions that the particles become stably dispersed therein.
Claim 2
Dependent Claim
318 words
A process for the production of a stable dispersion in a non-aqueous liquid medium of composite polymer microparticles having a diameter of from 0.1 to 10 microns, each of which comprises a core of crosslinked polymer surrounded by and grafted to a layer of non-crosslinked polymer, the process comprising the steps of (1) polymerising one or more ethylenically unsaturated monomers, including at least one crosslinking monomer, from which the crosslinked core polymer of the microparticles is to be derived, in an aqueous medium as hereinbefore defined at a temperature at least 10°C higher than the glass transition temperature of the core polymer in the presence in the aqueous medium as steric stabiliser of a block or graft copolymer which contains in the molecule a polymeric component which is solvatable by the aqueous medium and another polymeric component which is not solvatable by the aqueous medium and is capable of becoming associated with the polymer particles formed, the concentration of free monomer in the polymerisation mixture being maintained throughout this process step at a level such that at no time does the free monomer form a separate phase and the total amount of monomer polymerised being such that the resulting dispersion contains at least 20% by weight of microparticles, (2) polymerising, in the dispersion obtained from step (1), one or more further ethylenically unsaturated monomers, not including any crosslinking monomer, from which the non-crosslinked polymer of the outer layer is to be derived, optionally in the presence of additional block or graft copolymer stabiliser, the concentration of such further monomer in the free state in the polymerisation mixture being maintained at a level such that at no time does that free monomer form a separate phase, and (3) transferring the polymer microparticles from the resulting dispersion into a non-aqueous liquid medium which is a solvent for the non-crosslinkable polymer under such conditions that the particles become stably dispersed therein.
Claim 3
Dependent Claim
24 words
A process as claimed in claim 1, wherein the ethylenically unsaturated monomer is selected from acrylic acid, methacrylic acid and the alkyl esters thereof.
Claim 4
Dependent Claim
28 words
A process as claimed in claim 1 or claim 2, wherein the crosslinking monomer is a monomer which is poly- . functional with respect to the polymerisation reaction.
Claim 5
Dependent Claim
28 words
A process as claimed in any one of claims 1 to 3, wherein the temperature of polymerisation is at least 30°C higher than the polymerisation glass transition temperature.
Claim 6
Dependent Claim
24 words
A process as claimed in any one of claims 1 to 4, wherein the water-miscible constituent of the aqueous medium is methanol or ethanol.
Claim 7
Dependent Claim
68 words
A process as claimed in any one of claims 1 to 5, wherein the block or graft copolymer stabiliser is produced in situ during the polymerisation step (1) by introducing into the polymerisation mixture, before polymerisation begins, a precursor compound comprising in its molecule a polymeric component which is solvatable by the aqueous medium and an unsaturated grouping which is capable of copolymerising with the monomer or monomers.
Claim 8
Dependent Claim
37 words
A process as claimed in claim 6, wherein the solvatable polymeric component of the precursor compound is derived from a polyethylene glycol, or a monoalkyl ether thereof, having a molecular weight in the range 2000 - 4000.
Claim 9
Dependent Claim
39 words
A process as claimed in any one of claims 1 to 7, wherein the amount of further monomer polymerised in step (2) is at most 50% of the total weight of monomer used in steps (1) and (2) combined.
Claim 10
Dependent Claim
60 words
A process as claimed in any one of claims 1 to 8, wherein one or more of the further monomers polymerised in step (2) carries, in addition to the polymerisable group, a chemically functional group whereby the non-crosslinked polymer in the microparticles may become crosslinked by means of an external crosslinking agent after application of the composition to a substrate.
Claim 11
Dependent Claim
50 words
A process as claimed in any one of claims 1 to 9, wherein step (3) is accomplished by blending the aqueous dispersion obtained from step (2) with the non-aqueous medium and then removing the water and the water-miscible second constituent of the aqueous medium by distillation as an azeotropic mixture.
Claim 12
Dependent Claim
36 words
A coating composition comprising composite polymer microparticles produced by the process claimed in any one of claims 1 to 10 and a main film-forming constituent which is compatible with the non-crosslinked polymer component of the microparticles.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.