Foamed lon exchange plastics materials

Foamed ion-exchange plastics materials are prepared by incorporating ionizable groups either into a polymerizable compound which is then polymerized and foamed, or into a foamed polymer prepared from said polymerizable compound. By "foamed" is meant that the material is subjected to the mechanical introduction of gas to form pores or pockets in it. Monomers containing ionizable groups, e.g. p-phenolsulphonic acid, phenoxyacetic acid and acrylic acid and its derivatives may be polymerized with the polymerizable compound. The ion exchange capacity of the foamed plastics may be increased by treatment with a reagent containing ion exchange groups, e.g. chlorsulphonic acid. Plastics materials may be polyvinyl chloride, polyethylene, and polyvinyl formal. In the Examples (1) phenol is treated with the sodium salt of chloracetic acid and foamed in the presence of polyvinyl alcohol, formalin, hydrochloric acid and methyl cellulose, (2) phenol is sulphonated and foamed in the presence of polyvinyl alcohol, formalin and an emulsifying agent, (3) foamed polyvinyl chloride is treated with chlorsulphonic acid.