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.
Claims30
A process for encapsulating at least one organic target material in water-insoluble core/shell particles comprising
- (a) preparing core emulsion by emulsifying in water at high shear constituents comprising
- (1) organic target material to be encapsulated,
- (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) hydrophobic anionic surfactant,
- (5) water-insoluble emulsion stabilizer,
- (6) water-insoluble thermal polymerization initiator, and wherein said organic target material and hydrophilic solvents are non-solvents for polymer prepared by polymerizing said initial monomer,
- (b) heating said core emulsion to polymerize said initial monomer thereby forming core particles, and
- (c) adding at least one base selected from the group consisting of ammonia and the non-nucleophilic organic amines thereby neutralizing polymerized carboxylic acid and forming core/shell particles.
The process of claim 48 wherein the additional monomer is selected to yield a polymer having a calculated glass transition temperature greater than about 70.degree. C.
Dependencies are inferred from the claim text.