Imperial Chemical Industries Limited

Dulux Australia Ltd.

Morice W Thompson

John Bentley

Charles W Bromley

Alan J Backhouse

Clive W Graetz

Stephen P Davies

Arthur Topham

Peter F Nicks

Desmond W Osmond

Peter G Osborn

Auguste L Palluel

Patricia Lesley James

Brian Roy Asher

Wholly non-charged, sterically stabilized aqueous polymer dispersions are made by emulsifying ethylenically unsaturated monomer(s) of specified slight solubility in water and subjecting them in that state to polymerization in the presence of hydrogen peroxide and a non-ionic water-soluble activator compound and also in the presence of a steric stabilizer precursor compound containing a polymer chain which is soluble in the aqueous phase and an unsaturated grouping which can copolymerize with the monomer(s). The emulsification may be assisted by a conventional non-ionic surfactant, or alternatively the precursor compound may itself possess surface-active properties.

Polymerization process using nonionic surfactant and copolymerizable

Sterically stabilized aqueous polymer dispersions free from charged species are made by emulsifying in water ethylenically unsaturated monomer(s), soluble in water to the extent of 0.08%-8% by weight but giving rise to a polymer which is insoluble, and polymerizing the monomer(s) in that state in the presence of (a) a non-ionizable azo initiator which is water-soluble and substantially monomer-insoluble and (b) a block or graft copolymer stabilizer of specified structure.

Polymerization process

A process is described for making sterically stabilized non-aqueous dispersions of composite polymer microparticles, in which (1) monomers including at least one crosslinking monomer are polymerized in an aqueous medium at a temperature at least 10.degree. higher than the glass transition temperature of the polymer to be formed, in the presence of a block or graft copolymer stabilizing agent, under conditions such that there is at no time present a separate monomer phase, (2) further monomers, not including any crosslinking monomer, are polymerized 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-crosslinked 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-crosslinked component of the particles.

A crosslinkable coating composition is described which is miscible in all proportions with water and consists of crosslinked water-insoluble polymer microparticles sterically stabilised in dispersion in a liquid blend of a water-soluble crosslinking agent and a water-soluble, non-volatile substance of molecular weight less than 1000 which can take part in the crosslinking reaction but does not dissolve or swell the polymer, the amounts of the crosslinking agent and of the water-soluble non-volatile substance being up to 30% and 40% respectively of the total weight of film-forming material.

Coating compositions

A process is described for making sterically stabilized non-aqueous dispersions of polymer microparticles, in which (1) monomers including at least one crosslinking monomer are polymerized in an aqueous medium at a temperature at least 10.degree. higher than the glass transition temperature of the polymer to be formed, in the presence of a block or graft copolymer stabilizing agent containing in the molecule, as the component solvated by the aqueous medium, a polymer chain derived from a polyethylene glycol of molecular weight at least 1000, under conditions such that there is at no time present a separate monomer phase and (2) the microparticles thus obtained are transferred into a non-aqueous medium which is capable of dissolving the polyethylene glycol in question, when the latter is in the non-hydrated state, to the extent of at least 10% by weight at room temperature. The microparticles are of value for incorporation into coating compositions the main film-forming constituent of which is compatible with the polyethylene glycol-derived stabilizing chains of the particles.

Sterically stabilized aqueous polymer dispersions of at least 20% solids content are made by free radical-initiated polymerization of monomers in an aqueous medium at a temperature at least 10.degree. C. higher than the glass transition temperature of the polymer to be formed, in the presence of a compound which is soluble in the aqueous medium and contains in the molecule a polymeric component of molecular weight at least 1000 which is solvatable by the aqueous medium and an unsaturated grouping which can copolymerize with the monomers, the conditions being such that there is at no time present a separate monomer phase. The dispersions are useful as a basis of improved coating compositions.

Manufacture of aqueous polymer dispersions and coating compositions

Coating compositions are described in which the film-forming material consists of (a) 30-85% by volume of disperse particles of size 0.01-20 microns, of which not less than 50% by volume are non-crosslinked polyester microparticles, and (b) 70-15% by volume of a liquid continuous phase of viscosity 0.1-20 poise which is curable to a film-forming polymer by means of an autoxidative (i.e. air-drying) mechanism, the particles (a) being stably dispersed in the liquid (b) in a deflocculated state by means of an amphipathic steric stabilizing agent; the liquid continuous phase is composed of an autoxidizable derivative, such as a drying-oil fatty acid ester of a polyol in conjunction with a coreactive liquid such as an acrylic or methacrylic ester of a higher alcohol or a polyol.

A coating composition is provided in which the film-forming material consists of (a) 30-85% by volume of disperse phase particles of size 0.01-20 microns, of which not less than 50% are polymer microparticles, stably dispersed in (b) 70-15% by volume of a liquid continuous phase which is capable of curing by a condensation polymerization reaction, the total volume of components (a) and (b) being 100% and the disperse phase being capable of taking part in the curing reaction. The composition can have a very high solids content and makes possible the production of thick films free from surface shrinkage.

A dispersion of a condensation polymer in an organic liquid medium in which the polymer is insoluble is prepared by heating in the liquid medium one or more appropriate reactants one of which is present in the liquid disperse phase of an emulsion of which the continuous phase is constituted by the said liquid medium, in the presence dissolved in the liquid medium of a single-chain polymeric material of molecular weight between 1000 and 20,000 which carries at least one reactive group capable of taking part in the condensation polymer-forming reaction.

Process for the preparation of polymer dispersions

Coating compositions are described in which the film-forming material consists of (a) 30-85% by volume of disperse particles of size 0.01-20 microns, of which not less than 50% by volume are cross-linked polymer microparticles, and (b) 70-15% by volume of a liquid continuous phase of viscosity 0.1-20 poise which is curable to a film-forming polymer by means of an autoxidative (i.e. air-drying) mechanism, the particles (a) being stably dispersed in the liquid (b) in a deflocculated state by means of an amphipathic steric stabilizing agent. Typically, the polymer microparticles may be composed of a cross-linked polyester and the liquid continuous phase of a drying-oil fatty acid ester of a polyol, optionally in conjunction with a coreactive liquid such as an acrylic or methacrylic ester of a higher alcohol or a polyol.

Autoxidizable coating compositions

Compositions of matter comprising a finely divided dispersion of a solid having a particle size of less than 20 microns in an organic liquid selected from the class consisting of hydrocarbons and halogenated hydrocarbons containing dissolved therein an adduct of one or more compounds from each of the following classes

Dispersions

A process for manufacturing a stable dispersion in an organic liquid of particles consisting of (a) a polymer insoluble in the liquid and formed by polymerization of monomer(s) at least one of which is solid at the polymerization temperature and (b) sub-particles of a solid modifying agent for the polymer, the process comprising dispersing the solid monomer and the modifying agent together in the liquid in the presence of a specified dispersing agent so as to form a stable dispersion of solid particles not larger than 50.mu., and heating the dispersion together with any other monomers required, so as to bring about polymerization, in the presence of a specified stabilizing agent for the polymer formed. The functions of dispersing agent and stabilizing agent may be combined in a single substance.

Stable dispersions of polymer particles containing sub-particles of a

A process is described for the production of a stable dispersion of a copolymer, in particular of a copolyester, copolyamide or copolyesteramide, in a non-solvent organic liquid. The process involves the steps of (1) dispersing two or more comonomers, each of which is capable of undergoing homopolymerization and is solid at the copolymerization temperature, in the liquid with the aid of a defined monomer-stabilizing agent and so as to produce monomer particles no larger than 50.mu., and (2) heating the dispersion so obtained so as to bring about copolymerization, in the presence of a defined polymer-stabilizing agent. The copolymers so produced are believed to be different in structure from those obtained from the same comonomers by melt or solution copolymerization.

Polymer dispersions

A process is described for producing a dispersion of a condensation polymer in a hydrocarbon or chlorinated hydrocarbon liquid in which the polymer is insoluble, the disperse particles of polymer incorporating a pigment, filler or like modifying agent. At least one of the reactants from which the polymer is to be derived is heated in the liquid in the form of the liquid disperse phase of an emulsion in that liquid, made with the aid of a specified emulsifying agent, and the modifying agent is dispersed in that liquid disperse phase prior to completion of the polymer-forming reaction.

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Maidenhead, United Kingdom

Morice W Thompson