Mixing process
AssigneePolyvoltac Canada Inc.
InventorGary W. Boyce
Life of this patent
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Abstract
Viscous liquids containing polymeric materials which will interact with one another upon contact and generate gas for foam expansion are intimately and homogeneously mixed in a very short period of time by passing them successively and continuously through first and second rotary dynamic shearing mixers, the first mixer being considerably smaller than the second mixer, and the mixture experiencing a brief period of respite from shearing between the two mixers. The mixture experiences a much higher degree of shear in the first mixer, where the heat necessary for promoting the reaction is provided through the shearing action but without creating localized hot-spots. The process is particularly well suited for the preparation of foamed polydiorganosiloxanes, on a continuous, commercial scale.
Claims8
A process for the rapid preparation of a substantially homogeneous mixture of at least two viscous liquids containing interractable polydiorganosiloxanes and an appropriate catalyst system for generation of gas on interreaction thereof to cause foam expansion and rapid gelling of the mixture at room temperatures which comprises:
- bringing said liquids into initial mutual contact;
- continuously passing said mutually contacting liquids through a first, relatively small, rotary dynamic shearing mixer and subjecting said liquids to a high degree of rotary shearing agitation and mixing therein, with subdivision and recombination of portions of the mixture to dissipate localized heat generation substantially evenly throughout the bulk of the mixture;
- continuously delivering the mixed liquids from the first mixer to a rest zone through which the mixture moves without experiencing significant shear conditions;
- continuously delivering the mixed liquids from the rest zone to a second, relatively large, rotary dynamic shearing mixer and subjecting said liquid to a mild degree of rotary shearing agitation and mixing therein;
- and recovering a substantially homogeneous mixture of polydiorganosiloxanes and reaction product thereof from said second mixer;
- the time interval between said initial mutual contact and said recovering being not greater than about 3 minutes.
Dependencies are inferred from the claim text.