| 摘要 |
Production of a large granule starch protective material for pressure sensitive microencapsulated coatings, particularly in carbonless copy duplicating paper.
<??>An aqueous slurry of wheat barley or rye starch is fed to a first hydrocyclone, providing a partial separation of the granules. The overflow and underflow of this hydrocyclone are further separated in a second and third hydrocyclone, respectively. The underflow and overflow, respectively, of these are recirculated to the first hydrocyclone feed stream. The underflow stream leaving the third hydrocyclone contains 40% or more of the feed starch (dry basis) with a particle size distribution in which about 38% of the particles range from 20 to 32 microns and about 70% of the particles range from 16 to 32 microns.
<??>The best balance of the system, and the highest yield of large granule product, is obtained when the particle size distribution of the recirculation streams matches that of the feed stream.
<??>The large granule cereal starch product collected from the underflow of the second hydrocyclone may be further upgraded in average particle size by blending a minor amount of a large granule starch therewith.
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