Microsuspension process for preparing solvent core sequential polymer dispersion
AssigneeRohm and Haas Company
InventorsGeorge H. Redlich, Ronald W. Novak
Life of this patent
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Abstract
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.
Claims20
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 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, and
- (c) adding at least one base selected from the group consisting of ammonia and the organic amines thereby neutralizing polymerized carboxylic acid.
Dependencies are inferred from the claim text.