Redispersible polymer powders by redistribution of polyvinyl alcohol dispersant
AssigneeAir Products and Chemicals, Inc.
InventorsThomas E. Zeller, Randall P. Bright, Mark T. Phillips
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Abstract
A process for making a spray dried redispersible polymer powder, especially a VAE copolymer powder, by spray drying a polymer emulsion containing a polyvinyl alcohol redispersant. A sufficient amount of the total polyvinyl alcohol redispersant is added to the polymer emulsion prior to spray drying and the remaining amount of polyvinyl alcohol redispersant is added as a dry powder to the spray dried polymer powder.
Claims20
In a process for making a spray dried redispersible polymer powder by spray drying an aqueous polymer emulsion containing a polyvinyl alcohol redispersant, the improvement which comprises adding to the aqueous polymer emulsion prior to spray drying an amount of polyvinyl alcohol, which amount is a portion of the total polyvinyl alcohol content of the final powder product and is effective to redisperse the dry polymer powder from the spray drying in water, spray drying the polyvinyl alcohol-containing aqueous polymer emulsion to a dry polymer powder and mixing the remaining amount of the total polyvinyl alcohol content as dry particulate into the dry polymer powder.
In a process for making a spray dried redispersible polymer powder by spray drying an aqueous polymer emulsion containing a polyvinyl alcohol redispersant, the improvement which comprises adding to the aqueous polymer emulsion prior to spray drying an amount of polyvinyl alcohol, which amount is a portion of the total polyvinyl alcohol content of the final powder product, is effective to redisperse the dry polymer powder from the spray drying in water and is 2 to 40 wt. % based on the polymer content of the polymer emulsion, the added polyvinyl alcohol being 85 to 99 mole % hydrolyzed and having a DPn in the range of 140 to 2100, spray drying the polyvinyl alcohol-containing aqueous polymer emulsion to a dry polymer powder and mixing the remaining amount of the total polyvinyl alcohol content as dry particulate into the dry polymer powder, the remaining polyvinyl alcohol being 85 to 99 mole % hydrolyzed and having a DPn in the range of 335 to 1330 and a particle size in the range of 10 to 500 microns.
In a process for making a spray dried redispersible polymer powder by spray drying an aqueous polymer emulsion containing a polymer consisting essentially of vinyl acetate and 0 to 40 wt. % ethylene and a polyvinyl alcohol redispersant, the improvement which comprises adding to the aqueous polymer emulsion prior to spray drying an amount of polyvinyl alcohol, which amount is a portion of the total polyvinyl alcohol content in the final powder product, is effective to redisperse the dry polymer powder from the spray drying in water and is 4 to 20 wt. % based on the polymer content of the polymer emulsion, the added polyvinyl alcohol being 87 to 89 mole % hydrolyzed and having a DPn in the range of 335 to 1330, spray drying the polyvinyl alcohol-containing aqueous polymer emulsion to a dry polymer powder and mixing the remaining amount of the total polyvinyl alcohol content as dry particulate into the dry polymer powder, the remaining polyvinyl alcohol being 87 to 89 mole % hydrolyzed and having a DPn in the range of 335 to 605 and a particle size in the range of 10 to 175 microns.
Dependencies are inferred from the claim text.