초록 ▼

The present invention relates to a sequential polymerization process for preparing a water-insoluble dispersion of core/shell particles. In one embodiment the process may be employed to produce a particulate dispersion useful in making water-based coating compositions wherein on drying the particula

The present invention relates to a sequential polymerization process for preparing a water-insoluble dispersion of core/shell particles. In one embodiment the process may be employed to produce a particulate dispersion useful in making water-based coating compositions wherein on drying the particulate dispersion serves as an opacifying agent. In another embodiment the process may be employed to microencapsulate a hydrophobic target material, such as a biocide or herbicide.

대표청구항 ▼

A process for preparing an aqueous dispersion of water-insoluble core/shell particles comprising (a) preparing core emulsion by emulsifying in water at high shear a mixture comprising (1) at least one hydrophobic solvent, (2) at least one hydrophilic solvent, (3) initial monomer comprising at least

A process for preparing an aqueous dispersion of water-insoluble core/shell particles comprising (a) preparing core emulsion by emulsifying in water at high shear a mixture comprising (1) at least one hydrophobic solvent, (2) at least one hydrophilic solvent, (3) initial monomer comprising at least two polymerizable mono-alpha,beta-ethylenically unsaturated compounds wherein said initial monomer includes from about 2 to 4 percent by weight, based on total weight of said initial monomer of alpha,beta-ethylenically unsaturated carboxylic acid monomer, (4) anionic surfactant, (5) water-insoluble emulsion stabilizer, and (6) water-insoluble thermal polymerization initiator, wherein said mixture is a non-solvent for polymer prepared by polymerizing said initial monomer, (b) heating said core emulsion to suspension polymerize said initial monomer, thereby forming core particles, (c) adding at least one base selected from the group consisting of ammonia and the organic amines thereby neutralizing polymerized carboxylic acid and forming core/shell particles, and (d) adding additional monomer whereby said additional monomer is polymerized on said core/shell particles. A composition comprising an aqueous dispersion of water insoluble core/shell particles prepared by the process of claim 1 wherein the major portion of the core consists of said hydrophobic solvent and said hydrophilic solvent. A process which comprises mixing the aqueous dispersion of water-insoluble core/shell particles of claim 13 with an aqueous dispersion of particulate material selected from the group consisting of pigments, extenders, vinyl addition emulsion polymers, and mixtures thereof, to form a coating composition. A process according to claim 15 which comprises the additional steps of depositing a film of said coating composition on a solid substrate to be coated and/or impregnated, and subsequently drying the composition, forming single cavities in the core of substantially each of said particles so as to contribute to the opacity of said film.