Process and apparatus for the preparation of fine powders
OwnerDouglas S. Richartinventor
Life of this patent
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Abstract
Methods and means for grinding materials to fine powders in a media mill in which the materials are ground while immersed in a liquid. In the preferred embodiments, the liquid is a gas at room temperatures and pressures, the materials are resin mixtures and the fine powders are predominantly in a size range of from about 10 to about 40 micrometers. Other benefits may be achieved if the gas is in a supercritical state.
Claims17
A method for grinding in a media mill in which a coarse material is comminuted to a smaller particle size, the improvement comprising grinding coarse material in excess of 120 micrometers while it is immersed in a liquified gas, which is a gas at room temperature and under atmospheric pressure.
A method for controlling the particle size distribution of materials ground in a media mill which comprises grinding the materials in the presence of a liquefied gas, which liquefied gas is a gas at room temperatures and at atmospheric pressures.
A method for producing a powdered resin from a resin mixture in which the powdered resin has a particle size distribution such that the largest particles are less than 100 micrometers, the smaller particles are less than 12 micrometers, and the smaller particles are present in an amount less than 20 wt %, comprising the steps of:
- a. immersing the resin mixture in a liquefied gas which is a gas at room temperatures and atmospheric pressure to form a slurry, and
- b. grinding the slurry in a media mill.
A method for producing powdered resin from a resin mixture comprising the steps of:
- mixing the resin mixture with a liquefied gas that is in the supercritical state,
- solvating substantially all of the resin in the resin mixture,
- adjusting the temperature and pressure to yield a liquefied gas that is no longer in the supercritical state to precipitate the resin and form a slurry,
- grinding the slurry in a media mill, and
- vaporizing the liquefied gas from the slurry to form a dried powdered resin.
Dependencies are inferred from the claim text.