Patent ID: 7759455

Claim:
A process for preparing a polymer powder extract from a mixture of a polymer powder and a first particulate material, the process comprising: (a) suspending the mixture in a fluid, the fluid having a density adjustable throughout the range 0.90 to 1.0 g/cm 3 , to form a fluid suspension; (b) adjusting the density of the fluid so that either the first particulate material has a specific gravity relative to the fluid of more than 1 and the polymer powder has a specific gravity relative to the fluid of less than 1 or the first particulate material has a specific gravity relative to the fluid of less than 1 and the polymer powder has a specific gravity relative to the fluid of more than 1 whereby to cause the fluid suspension to form a first fraction which contains an amount of the first particulate material and a second fraction which contains substantially the whole of the polymer powder, (c) separating the first fraction from the second fraction; and (d) removing the fluid from the second fraction to obtain the polymer powder extract.