Process for preparing emulsions that are polymerizable to absorbent foam materials

Claim 2

A continuous process for the preparation of a high internal phase emulsion which is suitable for subsequent polymerization and dewatering to thereby form an absorbent foam material, which process comprises: A) providing a liquid feed stream of an oil phase comprising i) from about 3% to 41% by weight of a substantially water-insoluble, monofunctional glassy monomer component; ii) from about 27% to 73% by weight of a substantially water-insoluble, monofunctional rubbery comonomer component; iii) from about 8% to 30% by weight of a substantially water-insoluble, polyfunctional cross-linking agent component, and iv) from about 2% to 33% by weight of an emulsifier component which is soluble in the oil phase and which is suitable for forming a stable water-in-oil emulsion; B) providing a liquid feed stream of a water phase comprising an aqueous solution containing from about 0.2% to 40% by weight of water-soluble electrolyte; C) simultaneously introducing said liquid feed streams into a dynamic mixing zone at flow rates such the the initial weight ratio of water phase to oil phase being introduced ranges from about 2:1 to 10:1; D) subjecting the combined feed streams in said dynamic mixing zone to sufficient shear agitation to at least partially form an emulsified mixture in said zone while maintaining steady, non-pulsating flow rates for the oil and water phase stream; E) steadily increasing the ratio of water to oil feed streams being introduced into said dynamic mixing zone to within the range of from about 12:1 to 100:1 at a rate of increase which does not destroy the emulsified nature of the contents of said dynamic mixing zone, while maintaining the emulsified contents of said dynamic mixing zone at a temperature of from about 25° C. to 70° C., and while subjecting the emulsified contents of said zone to continued shear agitation which is sufficient to eventually form a high internal phase emulsion that, upon subsequent polymerization, provides a foam having an average cell size of from about 5 to 100 microns; F) continuously withdrawing the emulsified contents of said dynamic mixing zone and continuously introducing said emulsified contents into a static mixing zone wherein said emulsified contents are further subjected to sufficient shear mixing to thereby completely form a stable high internal phase emulsion having a water to oil phase weight ratio of from about 12:1 to 100:1; and G) continuously withdrawing said stable high internal phase emulsion from said static mixing zone such that said stable high internal phase emulsion can be thereafter polymerized and dewatered to form a solid absorbent foam.

Claim 3

A process according to claim 1 wherein: A) the glassy monomer component comprises from about 7% to 40% by weight of the oil phase; B) the rubbery comonomer component comprises from about 27% to 66% by weight of the oil phase; C) the cross-linking agent component comprises from about 10% to 25% by weight of the oil phase; D) the emulsifier component comprises from about 4% to 25% by weight of the oil phase; and E) the water phase comprises an aqueous solution containing from about 0.05% to 20% by weight of the electrolyte.

Claim 4

A process according to claim 2 wherein: A) the initial weight ratio of the water phase to oil phase introduced into the dynamic mixing zone ranges from about 2.5:1 to 5:1; B) the weight ratio of the water phase to oil phase introduced into the dynamic mixing zone is increased to within the rage of from about 20:1 to 70:1; and C) the water to oil phase weight ratio of the stable high internal phase emulsion formed in the static mixing zone ranges from about 20:1 to 70:1.

Claim 5

A process according to claim 3 wherein: A) the temperature of the emulsified contents of the dynamic mixing zone is maintained within the range of from about 35° to 65° C.; and B) shear agitation is imparted to the emulsified contents of the dynamic mixing zone to the extent which is sufficient to eventually form a high internal phase emulsion that, upon subsequent polymerization, provides a foam having an average cell size of from about 10 to 90 microns.

Claim 6

A process according to claim 4 wherein: A) the substantially water-insoluble, monofunctional glassy monomer component of the oil phase comprises one or more styrene-based monomer types; B) the substantially water-insoluble, monofunctional rubbery comonomer component of the oil phase comprises comonomer types selected from butylacrylate, 2-ethylhexylacrylate, butadiene, isoprene and combinations of these comonomer types; C) the substantially water-insoluble cross-linking agent component of the oil phase comprises a difunctional monomer type selected from divinylbenzene, divinyltolulene, diallylphthalate, one or more diacrylic acid esters of a polyol or combinations of such difunctional monomer types; and D) the emulsifier component of the oil phase comprises an emulsifier selected from sorbitan fatty acid esters, polyglycerol fatty acid esters, polyoxyethylene fatty acids and esters and combinations of such emulsifiers.

Claim 7

A process according to claim 5 wherein: A) the molar ratio of monofunctional glassy monomer component to monofunctional rubbery comonomer component in the oil phase ranges from about 1:25 to 1.5:1; and B) the cross-linking agent component is present in a concentration ranging from about 5 to 60 mole percent, based on total monomers present in the oil phase.

Claim 8

A process according to claim 5 wherein: A) the water-soluble electrolyte in the water phase comprises one or more water-soluble salts of an alkali metal or alkaline earth metal; and B) the water phase additionally comprises from about 0.02% to 0.4% by weight of a water-soluble, free radical polymerization initiator.

Claim 9

A process according to claim 7 wherein shear agitation of from about 1000 to 7000 sec. -1 is imparted to the combined water and oil phase feed streams in the dynamic mixing zone.

Claim 10

A process according to claim 8 wherein shear agitation is imparted to the emulsified contents of the dynamic mixing zone by means of a pin impeller.

Claim 11

A process according to claim 9 wherein the shear agitation imparted to the emulsified contents of the static mixing zone ranges from about 100 to 7000 sec. -1 .

Claim 12

A process according to claim 9 wherein the water phase liquid feed stream is initially fed to the dynamic mixing zone at the pilot plant scale flow rate of from about 0.04 to 2.0 liters/minute and the oil phase liquid feed stream is initially fed to the dynamic mixing zone at the pilot plant scale flow rate of from about 0.02 to 0.2 liter/minute.

Claim 13

A process according to claim 11 wherein, after the water to oil phase ration has been increased, the effluent from the dynamic mixing zone is withdrawn at the pilot plant scale flow rate of from about 0.8 to 2.2 liters/minute.

Claim 14

A process according to claim 9 wherein the water phase liquid feed stream is initially fed to the dynamic mixing zone at the commercial scale flow rate of from about 25 to 250 liters/minute and the oil phase liquid feed stream is initially fed to the dynamic mixing zone at the commercial scale flow rate of from about 10 to 25 liters/minute.

Claim 15

A process according to claim 13 wherein, after the water to oil phase ratio has been increased, the effluent from the dynamic mixing zone is withdrawn at the commercial scale flow rate of from about 35 to 800 liters/minute.

Claim 16

A continuous process for the preparation of a high internal phase emulsion which is suitable for subsequent polymerization and dewatering to form an absorbent foam material, which process comprises: A) providing a liquid feed stream of an oil phase comprising i) from about 7% to 40% by weight of a styrene monomer component; ii) from about 27% to 66% by weight of a comonomer component selected from butylacrylate, 2-ethylhexylacrylate, isoprene, and combinations of these comonomers; iii) from about 10% to 25% by weight of a divinylbenzene cross-linking agent component, and iv) from about 4% to 25% by weight of an emulsifier component selected from sorbitan monooleate and a mixture of sorbitan monooleate and sorbitan trioleate in a monooleate to trioleate weight ratio of from about 2:1 to 5:1; B) providing a liquid feed stream of a water phase comprising an aqueous solution containing from about 0.5% to 20% by weight of calcium chloride and from about 0.1% to 0.2% by weight of a water-soluble, free radical polymerization initiator; C) simultaneously introducing said liquid feed streams into a dynamic mixing zone at flow rates such that the initial weight ratio of water phase to oil phase being introduced ranges from about 2.5:1 to 5:1; D) subjecting the combined feed streams in said dynamic mixing zone to shear agitation of from about 1500 to 3000 sec. -1 for a period of time sufficient to at least partially form an emulsified mixture in said zone while maintaining steady, non-pulsating flow rates for the oil and water phase streams; E) steadily increasing the ratio of water to oil feed streams being introduced into said dynamic mixing zone to within the range of from about 20:1 to 70:1 at a rate of increase which does not destroy the emulsified nature of the contents of said dynamic mixing zone, while maintaining the emulsified contents of said dynamic mixing zone at a temperature of from 35° C. to 65° C., and while subjecting the emulsified contents of said zone to continued shear agitation of from about 1500 to 3000 sec. -1 for a period of time which is sufficient to form a high internal phase emulsion that, upon subsequent polymerization, provides a foam having an average cell size of from about 10 to 90 microns; F) continuously withdrawing the emulsified contents of said dynamic mixing zone and continuously introducing said emulsified contents into a static mixing zone wherein said emulsified contents are further subjected to sufficient shear mixing to thereby completely form a stable high internal phase emulsion having a water to oil phase weight ratio of from about 20:1 to 70:1; and G) continuously withdrawing said stable high internal phase emulsion from said static mixing zone such that said stable high internal phase emulsion can be thereafter polymerized and dewatered to form a solid absorbent foam.

Claim 17

A continuous process for the preparation of a high internal phase emulsion which is suitable for subsequent polymerization and dewatering to form an absorbent foam material, which process comprises: A) providing a liquid feed stream of an oil phase comprising i) from about 7% to 40% by weight of a styrene monomer component; ii) from about 27% to 66% by weight of a comonomer component selected from butylacrylate, 2-ethylhexylacrylate, isoprene, and combinations of these comonomers; iii) from about 10% to 25% by weight of a divinylbenzene cross-linking agent component, and iv) from about 4% to 25% by weight of an emulsifier component selected from sorbitan monooleate and a mixture of sorbitan monooleate and sorbitan trioleate in a monooleate to trioleate weight ratio of from about 2:1 to 5:1; B) providing a liquid feed stream of a water phase comprising an aqueous solution containing from about 0.5% to 20% by weight of calcium chloride and from about 0.1% to 0.2% by weight of a water-soluble, free radical polymerization initiator; C) simultaneously introducing said liquid feed streams into a dynamic mixing zone at flow rates such that the initial weight ratio of water phase to oil phase being introduced ranges from about 2.5:1 to 5:1; D) subjecting the combined feed streams in said dynamic mixing zone to shear agitation of from about 1500 to 3000 sec. -1 for a period of time sufficient to at least partially form an emulsified mixture in said zone while maintaining steady, non-pulsating flow rates for the oil and water phase streams; E) steadily increasing the ratio of water to oil feed streams being introduced into said dynamic mixing zone to within the range of from about 20:1 to 70:1 at a rate of increase which does not destroy the emulsified nature of the contents of said dynamic mixing zone, while maintaining the emulsified contents of said dynamic mixing zone at a temperature of from 35° C. to 65° C., and while subjecting the emulsified contents of said zone to continued shear agitation of from about 1500 to 3000 sec. -1 for a period of time which is sufficient to form a high internal phase emulsion that, upon subsequent polymerization, provides a foam having an average cell size of from about 10 to 90 microns; F) continuously withdrawing the emulsified contents of said dynamic mixing zone and continuously introducing said emulsified contents into a static mixing zone wherein said emulsified contents are further subjected to sufficient shear mixing to thereby completely form a stable high internal phase emulsion having a water to oil phase weight ratio of from about 20:1 to 70:1; and G) continuously withdrawing said stable high internal phase emulsion from said static mixing zone such that said stable high internal phase emulsion can be thereafter polymerized and dewatered to form a solid absorbent foam.