Method and apparatus for foaming high viscosity polymer materials

Apparatus for mixing gas with a fluid plymeric material to form a polymer/gas solution at a pressure above atmospheric pressure comprising, in combination:

• a pair of substantially parallel, oppositely driven shafts each having a series of spaced disks substantially perpendicular to the axis thereof,
• the disks on one shaft intermeshing with the disks on the other shaft,
• a housing surrounding said intermeshing disks,
• said disks serving to divide said housing into a series of compartments along its length,
• polymeric material inlet means at one end of said housing,
• polymer/gas solution outlet means at the other end of said housing,
• means for introducing a gas into said housing under pressure, and
• means for driving said shafts and in turn said disks of said shafts to cause mixing of said gas with said polymer within said compartments to form said polymer/gas solution upstream of said polymer/gas solution outlet means,
• said mixing apparatus adapted to be force fed with said polymeric material by a separate pump in line upstream of said inlet means through said housing to said outlet means such that said gas is maintained in solution with said polymeric material in said apparatus housing for dispensing said polymer/gas solution to atmospheric pressure as a foam with a low pressure drop across said inlet to said means outlet to avoid premature foaming of said polymeric material in said housing.

Apparatus for mixing gas with a fluid polymeric material to form a polymer/gas solution at a pressure above atmospheric pressure comprising, in combination:

• at least one rotatable shaft including a first series of spaced disks substantially perpendicular to the axis thereof and rotatable therewith about said axis,
• a second series of spaced disks fixed with respect to said first series of spaced disks and intermeshing therewith,
• a housing surrounding said intermeshing disks,
• said disks serving to divide said housing into a series of compartments along its length,
• polymeric material inlet means at one end of said housing,
• polymer/gas solution outlet means at the other end of said housing,
• means for introducing a gas into said housing, and
• means for driving said rotatable shaft to cause said first series of disks to rotate with respect to said second series of disks to cause mixing of said gas with said polymer within said housing to form said polymer/gas solution upstream of said polymer/gas solution outlet means,
• said mixing apparatus adapted to be force fed with said polymeric material by a separate pump in line upstream of said inlet means through said housing to said outlet means such that said gas is maintained in solution with said polymeric material in said apparatus housing for dispensing said polymer/gas solution to atmospheric pressure as a foam with a low pressure drop across said inlet to said outlet means to avoid premature foaming of said polymeric material in said housing.

Apparatus for mixing gas with a fluid polymeric material to form a polymer/gas solution at a pressure above atmospheric pressure comprising, in combination:

• at least one rotatable shaft including a first series of spaced disks substantially perpendicular to the axis thereof and rotatable therewith about said axis,
• a housing surrounding said shaft and disks,
• said disks serving to divide said housing into a series of compartments along its length,
• polymeric material inlet means at one end of said housing,
• polymer/gas solution outlet means at the other end of said housing,
• means for introducing a gas into said housing, and
• means for driving said rotatable shaft to cause said disks to rotate to cause mixing of said gas with said polymer within said housing to form said polymer/gas solution upstream of said polymer/gas solution outlet means,
• said mixing apparatus adapted to be force fed with said polymeric material by a separate pump in line upstream of said inlet means through said housing to said outlet means such that said gas is maintained in solution with said polymeric material in said apparatus housing for dispensing said polymer/gas solution to atmospheric pressure as a foam with a low pressure drop across said inlet to said outlet means to avoid premature foaming of said polymeric material in said housing.

Apparatus for mixing gas with a fluid polymeric material to form a polymer/gas solution at a pressure above atmospheric pressure comprising, in combination:

• a tubular housing for containing said gas and polymeric material under pressure having an inner wall,
• a shaft extending along the length of said housing,
• a series of spaced disks on said shaft substantially perpendicularly to the axis thereof,
• the disks on the shaft having a plurality of teeth spaced about their circumferences with slots therebetween, the teeth extending out toward said inner wall of said housing while permitting rotation of said shaft within said housing,
• said disks and said slots in said disks serving to divide said housing into a series of compartments spaced about said inner wall and along the length of the housing movable in a circumferential direction with respect to the fixed housing inner wall,
• polymeric material and gas inlet means at one end of said housing, and
• polymer/gas solution outlet means at the other end of said housing,
• said shaft being adapted to be rotated in turn rotating said disks on said shaft to cause mixing of said gas with said polymer within said compartments and between said disks to form said polymer/gas solution upstream of said polymer/gas solution outlet means,
• said mixing appratus adapted to be force fed with said polymeric material by a separate pump in line upstream of said inlet means through said housing to said outlet means such that said gas is maintained in solution with said polymeric material in said apparatus housing for dispensing said polymer/gas solution to atomospheric pressure as a foam with a low pressure drop across said inlet to said outlet means to avoid premature foaming of said polymeric material in said housing.

Apparatus for mixing gas with a fluid polymeric material to form a polymer/gas solution at a pressure above atmospheric pressure comprising:

• a pump in a processing line for said polymeric material upstream of a separate low energy mixer, said pump adapted for force feeding said polymeric material through said mixer, said low energy mixer comprising:
• (a) a tubular housing for containing said gas and polymeric material under pressure having an inner wall,
• (b) a shaft extending along the length of said housing,
• (c) a series of spaced disks on said shaft substantially perpendicularly to the axis thereof,
• the disks on the shaft having a plurality of teeth spaced about their circumferences with slots therebetween, the teeth extending out toward said inner wall of said housing while permitting rotation of said shaft within said housing,
• said disks and said slots in said disks serving to divide said housing into a series of compartments spaced about said inner wall and along the length of the housing movable in a circumferential direction with respect to the fixed housing inner wall,
• (d) polymeric material and gas inlet means at one end of said housing,
• (e) polymer/gas solution outlet means at the other end of said housing,
• said shaft being adapted to be rotated and in turn rotating said disks on said shaft to cause mixing of said gas with said polymer within said compartments and between said disks to form said polymer/gas solution upstream of said polymer/gas solution outlet means,
• said low energy mixer adapted to be force fed with said polymeric material through said housing to said outlet means such that said gas is maintained in solution with said polymeric material in said housing for dispensing said polymer/gas solution to atomospheric pressure as a foam with a low pressure drop across said inlet to said outlet means to avoid premature foaming of said polymeric material in said housing.

Apparatus for mixing gas with a fluid polymeric material to form a polymer/gas solution at a pressure above atmospheric pressure comprising:

• a piston pump in a processing line for said polymeric material upstream of a separate low energy mixer, said pump adapted for force feeding said polymeric material from said source through said mixer without detrimentally raising the temperature of the polymer material thereby avoiding an adverse reaction or premature foaming thereof,
• said low energy mixer comprising:
• (a) a tubular housing for containing said gas and polymeric material under pressure having an inner wall,
• (b) a shaft extending along the length of said housing,
• (c) a series of spaced disks on said shaft substantially perpendicularly to the axis thereof,
• the disks on the shaft having a plurality of teeth spaced about their circumferences with slots therebetween, the teeth extending out toward said inner wall of said housing while permitting rotation of said shaft with said housing,
• said disks and said slots in said disks serving to divide said housing into a series of compartments spaced about said inner wall and along the length of the housing movable in a circumferential direction with respect to the fixed housing inner wall,
• (d) polymeric material and gas inlet means at one end of said housing,
• (e) polymer/gas solution outlet means at the other end of said housing,
• said shaft being adapted to be rotated in turn rotating said disks on said shaft to cause mixing of said gas with said polymer within said compartments and between said disks to form said polymer/gas solution upstream of said polymer/gas solution outlet means,
• said low energy mixer adapted to be force fed with said polymeric material through said housing to said outlet means such that said gas is maintained in solution with said polymeric material in said housing for dispensing said polymer/gas solution to atomospheric pressure as a foam with a low pressure drop across said inlet to said outlet to avoid premature foaming of said polymeric material in said housing.
• said low energy mixer adapted to be force fed with said polymeric material through said housing to said outlet means such that said gas is maintained in solution with said polymeric material in said housing for dispensing said polymer/gas solution to atomospheric pressure as a foam with a low pressure drop across said inlet to said outlet to avoid premature foaming of said polymeric material in said housing.