Manufacturing method of resin granules
AssigneeNippon Paint Co., Ltd.
InventorsHaruhiko Sato, Naoya Yabuuchi, Shinji Seo, Takehiro Ojima
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Abstract
The present invention provides a method which makes it possible to manufacture substantially spherical resin granules with a narrow grain size distribution by a simple operation. According to the present invention, there is provided a method of manufacturing resin granules with a grain diameter of 1.about.100 .mu.m and narrow grain size distribution by controlling the cloud point of polyvinyl alcohol and other water soluble polymers.
Claims8
A method of manufacturing resin granules with a grain diameter of 1 to 100 .mu.m and a narrow grain size distribution of less than 30% variation coefficient, comprising
- mixing the following three components:
- (a) either a polyvinyl alcohol having a saponification degree of 60 to 85% and a cloud point of 30.degree. to 90.degree. C., or a polyvinyl alcohol solution obtained by adding an electrolyte salt to polyvinyl alcohol having a saponification degree of more than 85% to adjust the cloud point within 30.degree. to 90.degree. C. or a mixture thereof,
- (b) an aqueous solution comprising at least one kind of a water soluble polymer having a cloud point of 30.degree. to 90.degree. C., selected from the group consisting of methyl cellulose, hydroxypropyl cellulose, polyethylene glycol alkyl ether and a block copolymer of polyethylene glycol-polypropylene glycol, and
- (c) a granule forming component containing a polymerizing monomer,
- at a temperature below the cloud point of the polyvinyl alcohol and water soluble polymer, thus obtaining fine primary granules of less than 10 .mu.m,
- heating the granules to a temperature above the cloud point to obtain substantially spherical granules with a grain diameter increased about 2 to 20 times, and
- then polymerizing the polymerizing monomer during heating or after formation of granules.
A method of manufacturing resin granules with a grain diameter of 1 to 100 .mu.m and a narrow grain size distribution of less than 30% variation coefficient, comprising
- mixing the following three components:
- (a) either a polyvinyl alcohol having a saponification degree of 60 to 85% and a cloud point of 30.degree. to 90.degree. C., or a polyvinyl alcohol solution obtained by adding an electrolyte salt to polyvinyl alcohol having a saponification degree of more than 85% to adjust the cloud point within 30.degree. to 90.degree. C., or a mixture thereof,
- (b) an aqueous solution comprising at least one kind of water soluble polymer having a cloud point of 30.degree. to 90.degree. C. selected from the group consisting of methyl cellulose, hydroxypropyl cellulose, polyethylene glycol alkyl ether and a block copolymer of polyethylene glycol-polypropylene glycol, and
- (c) a granule forming component containing an isocyanate component,
- at a temperature below the cloud point of the polyvinyl alcohol and water soluble polymer, thus obtaining fine primary granules of less than 10 .mu.m.
- heating the granules to a temperature above the cloud point to obtain substantially spherical granules with a grain diameter increased to about 2 to 20 times, and
- then cooling below the cloud point and adding thereto a water-solution of an amino compound to perform interfacial polymerization.
Dependencies are inferred from the claim text.