Patent GB-1017676-A (GB)
Title: Process for coating liquid or solid particles with a liquid polymer phase in non-aqueous solvent systems
IPC: A01N25/28
Filed: 1964-09-16
Abstract: In a process for coating liquid or solid particles with a liquid polymer phase in non-aqueous solvent systems, the particles are dispersed in an organic solvent solution of the polymer, to which solution an organic non-solvent for said particles and said polymer is added, which non-solvent is miscible with said organic solvent, thereby causing the polymer to separate out from solution and deposit around the dispersed particles, a mineral silicate being intermittently added during the addition of said non-solvent.  The particles coated may be solids, e.g. dyes such as amaranth, or alizarimcyanine dye; or liquids, such as suspensions or solutions of dyes.  The coating material may be natural or synthetic rubber; ethyl cellulose, cellulose nitrate, benzyl cellulose, cellulose acetate or cellulose acetate-butyrate; poly-styrene or styrene-maleic acid copolymer; polyethylene, polypropylene or polybutylene; or polyvinyl acetate, chloride or fluoride.  The silicate may be bentonite, kaolin, pumice, purified siliceous earth or talc, and is preferably used in an amount of from 2 12 to 5 times the amount of polymer.  In examples, (5) alizarine-cyanine dye is coated with ethyl cellulose and purified siliceous earth, (6) the coated dye particles of (5) are further coated with cellulose acetobutyrate and talc, and are then sprayed on to a paper substrate, (7) amaranth is coated with cellulose acetate and kaolin.ALSO:In a process for coating liquid or solid particles with a liquid polymer phase in non-aqueous solvent systems, the particles are dispersed in an organic solvent solution of the polymer, to which solution an organic non-solvent for said particles and said polymer is added, which non-solvent is miscible with said organic solvent, thereby causing the polymer to separate out from solution and deposit around the dispersed particles, a mineral silicate being intermittently added during the addition of said non-solvent. The particles coated may be liquids, e.g. phloroglucinol dihydrate, urea, and p-diazodimethyl-aniline-zinc chloride double salt.  The coating material may be natural or synthetic rubber; ethyl cellulose, cellulose nitrate, benzyl cellulose, cellulose acetate or cellulose acetatebutyrate; polystyrene or styrene-maleic acid copolymer; polyethylene, polypropylene or polybutylene; or polyvinyl acetate, chloride or fluoride.  The silicate may be bentonite, kaolin, pumice, purified siliceous earth or talc, and is preferably used in an amount of from 2 1/2 to 5 times the amount of polymer.ALSO:In a process for coating liquid or solid particles with a liquid polymer phase in non-aqueous solvent systems, the particles are dispersed in an organic solvent solution of the polymer, to which solution an organic non-solvent for said particles and said polymer is added, which non-solvent is miscible with said organic solvent, thereby causing the polymer to separate out from solution and deposit around the dispersed particles, a mineral silicate being intermittently added during the addition of said non-solvent.  The particles coated may be solids, e.g. fertilizers such as dibasic calcium phosphate or ammonium nitrate, or liquids, e.g. dilute acid solutions or solutions of trisodium phosphate, or zinc chloride.  The coating material may be natural or synthetic rubber; ethyl cellulose, cellulose nitrate, benzyl cellulose, cellulose acetate or cellulose acetate-butyrate; polystyrene or styrene-maleic acid co-polymer; polyethylene, polypropylene or polybutene; or polyvinyl acetate, chloride or fluoride.  The silicate may be bentonite, kaolin, pumice, purified siliceous earth or talc, and is preferably used in an amount of from 2 1/2 to 5 times the amount of polymer.  In an example, dibasic calcium phosphate is coated with cellulose acetobutyrate and bentonite.ALSO:In a process for coating liquid or solid particles with a liquid polymer phase in non-aqueous solvent systems, the particles are dispersed in an organic solvent solution of the polymer, to which solution an organic non-solvent for said particles and said polymer is added, which non-solvent is miscible with said organic solvent, thereby causing the polymer to separate out from solution and deposit around the dispersed particles, a mineral silicate being intermittently added during the addition of said non-solvent.  The particles coated may be solids, e.g. pharmaceuticals such as methylprednisolone, tolbutamide sodium, thiamine mononitrate, or methscopolamine bromide; dyes such as amaranth, or alizarine-cyanine dye; fertilisers such as dibasic calcium phosphate or ammonium nitrate; weed toxicants such as sodium 2,4-dichlorophenoxy acetate; or liquids, e.g. water; dilute acid or alkali solutions; or dispersions of dyes, reagents, pharmaceuticals, fertilisers, adhesives and developers, including solutions of trisodium phosphate, phoroglucinol dihydrate, urea, zinc chloride, and p-diazodimethylaniline-zinc chloride double salt, as well as solutions of many of the solids mentioned above. The coating material may be natural or synthetic rubber; ethyl cellulose, cellulose nitrate, benzyl cellulose, cellulose acetate or cellulose acetate-butyrate; polystyrene or styrene-maleic acid co-polymer; polyethylene, polypropylene or polybutylene; or polyvinyl acetate, chloride or fluoride.  The silicate may be bentonite, kaolin, pumice, purified siliceous earth or talc, and is preferably used in an amount of from 2 1/2 -5 times the amount of polymer.  In examples, (1) methylprednisolone is coated with styrene-maleic acid co-polymer and talc, (2) methylprednisolone is coated with polyvinyl acetate and talc, (3) dibasic calcium phosphate is coated with cellulose acetobutyrate and bentonite, (4) sodium 2,4-dichlorophenoxy acetate is coated with benzyl cellulose and kaolin, (5) alizarine-cyanide dye is coated with ethyl cellulose and purified siliceous earth, (6) the coated dye particles of (5) are further coated with cellulose acetobutyrate and talc, and are then sprayed on to a paper substrate, (7) amaranth is coated with cellulose acetate and kaolin, (8) aqueous particles containing phoroglucinol dihydrate, sodium acetate, urea and polyethylene glycol are coated with ethyl cellulose and pumice, and are then sprayed on to a film, and (9) aqueous particles containing 4-dimethyl amino benzene diazonium chloride-zinc chloride double salt, zinc chloride, citric acid, and thiourea are coated with ethyl cellulose and kaolin.ALSO:In a process for coating liquid or solid particles with a liquid polymer phase in non-aqueous solvent systems, the particles are dispersed in an organic solvent solution of the polymer, to which solution an organic non-solvent for said particles and said polymer is added, which non-solvent is miscible with said organic solvent, thereby causing the polymer to separate out from solution and deposit around the dispersed particles, a mineral silicate being intermittently added during the addition of said non-solvent.  The particles coated may be solids, e.g. pharmaceuticals such as methylprednisolone, tolbutamide sodium, thiamine monitrate, or methscopolamine bromide; weed toxicants such as sodium 2, 4-dichlorophenoxyacetate; or liquids, e.g. pharmaceuticals, including solutions of many of the solids mentioned above.  The coating material may be natural or synthetic rubber; ethyl cellulose, cellulose nitrate, benzyl cellulose, cellulose acetate or cellulose acetatebutyrate; polystyrene or styrene-maleic acid co-polymer; polyethylene, polypropylene or polybutylene; or polyvinyl acetate, chloride or fluoride.  The silicate may be bentonite, kaolin, pumice, purified siliceous earth or talc, and is preferably used in an amount of from 2 1/2 to 5 times the amount of polymer.  In examples, (1) methylprednisolone is coated with styrene-maleic acid co-polymer and talc, (2) methylprednisolone is coated with polyvinyl acetate and talc, (4) sodium 2, 4-dichlorophenoxy acetate is coated with benzyl cellulose and kaolin.