Polyvinyl acetals with improved residual particle size distribution
AssigneeKuraray Europe GmbH
InventorsFlorian MUMMY, Christian JANSSEN
Life of this patent
Estimating the term…
Abstract
The invention is directed to the polyvinyl acetals with an improved residual particle size, methods for the production of such polyvinyl acetals and their use as binder for the production of ceramic green sheets.
Claims13
A process for the production of a polyvinyl acetal powder comprising the steps of
- a. reacting a polyvinyl alcohol with an aldehyde in the presence of an acid to prepare the polyvinyl acetal,
- b. precipitating the polyvinyl acetal obtained in step a,
- c. washing the precipitate obtained in step b with a washing liquid comprising water, and
- d. drying the washed precipitate of step c,
- wherein the washing liquid in step c contains equal to or less than 100 mg/l chloride ions.
A polyvinyl acetal with a residual particle count of particles with a particle size from 2 to 500 mm of equal to or less than 500 counts/ml and with a ratio of the residual particle count of particles with a particle size from 2 to 5 mm divided by the residual particle count of particles with a particle size from 2 to 20 mm of equal to or less than 0.8 wherein the residual particle count is measured as described in the description in a 2% by weight solution in a 1:1 mixture of toluene and ethanol.
Dependencies are inferred from the claim text.