Reduction of unpolymerized monomers in high internal phase emulsion foam

Abstract

A method for using Ultraviolet light to reduce the level of unpolymerized monomer in a High Internal Phase Emulsion (HIPE) foam.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims the benefit of U.S. Provisional Application No. 61 / 290,947 filed on 30 Dec. 2009, the substance of which is incorporated herein by reference.FIELD OF THE INVENTION[0002]This application relates to a process for the reduction of unpolymerized monomers in High Internal Phase Emulsion (HIPE) foam.BACKGROUND OF THE INVENTION[0003]An emulsion is a dispersion of one liquid in another liquid and generally is in the form of a water-in-oil mixture having an aqueous or water phase dispersed within a substantially immiscible continuous oil phase. Water-in-oil (or oil in water) emulsions having a high ratio of dispersed aqueous phase to continuous oil phase are known in the art as High Internal Phase Emulsions, also referred to as “HIPE” or HIPEs. At relatively high dispersed aqueous phase to continuous oil phase ratios the continuous oil phase becomes essentially a thin film separating and coating the droplet-like structures ...

AI Technical Summary

Benefits of technology

[0006]A method is provided for producing a High Internal Phase Emulsion foam comprising the steps of forming a High Internal Phase Emulsion from an oil phase comprising monomer, cross-linking agent, emulsifier; photoinitiator; and an aqueous phase; depositing the High Internal Phase Emulsion on a belt; polymerizing the monomer component in the oil phase of the High Internal Phase Emulsion using a polymerization reaction that is conducted at a temperature of from about 25° C. to about 150° C. for a time sufficient to form a High Internal Phase Emulsion foam; and reducing the amount of unpolymerized monomer in the High Internal Phase Emulsion foam to less than 400 ppm by exposing the High Internal Phase Emulsion foam to UV light from a UV light source.

[0007]A method is provided for producing a High Internal Phase Emulsion foam comprising the steps of forming a first High Internal Phase Emulsion from an oil phase comprising: monomer, cross-linking agent, emulsifier; photoinitiator; and an aqueous phase; forming a second High Internal Phase Emulsion from an oil phase comprising: monomer, cross-linking agent, emulsifier; photoinitiator; and an aqueous phase; depositing the first High Internal Phase Emulsion on a belt; depositing the second High Internal Phase Emulsion on the first High Internal Phase Emulsion; and polymerizing the monomer component in the oil phase of the first and second High Internal Phase Emulsion using a polymerization reaction that is conducted at a temperature of from about 25° C. to about 150° C. for a time sufficient to from a High Internal Phase Emulsion foam; and reducing the amount of unpolymerized monomer in the High Internal Phase Emulsion foam to less than 400 ppm by exposing the High Internal Phase Emulsion foam to UV light from a UV light source.

Problems solved by technology

However, after the addition of initiator and the curing process not all of the monomers are polymerized.

These residual unpolymerized monomers can cause problems both in the HIPE foam and the process used to prepare the HIPE foams.

If unreacted monomers are present in the HIPE foam they may pose a safety concern at certain levels, adversely affect the desired HIPE foam properties or interfere with the further HIPE foam processing steps, such as cutting or the application of other components to the HIPE foam.

In addition, the monomers also have a tendency to adhere to surfaces which can cause processing problems both in batch processes where the monomers may adhere to the mold cavity requiring cleaning of the molds or in the case of a continuous process requiring the cleaning of the surface upon which a HIPE is deposited onto.

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