2343897-A cites 4 patents.
This invention relates to a polymeric composition having ultraviolet light and heat resistance that can be molded into rubbery articles that can be magnetized. For instance, the rubbery compositions of this invention can be molded into magnetic seals for refrigerator or freezer doors. In such applications, the magnetic composition acts as a combination airtight gasket and magnetic closure device for the refrigerator or freezer. These polymeric magnetic compositions offer the advantage of being thermoplastic materials rather than thermosets. By virtue of being thermoplastics, they can be injection-molded into the desired form without the need for a curing step. Thus, rubbery magnetic compositions can be manufactured by a simpler, less costly process by utilizing the compositions of this invention.; This invention more specifically discloses a polymeric magnet composition which is comprised of (1) from 5 to 19 parts by weight of a rubbery polymer which is comprised of repeat units which are comprised of (a) butyl acrylate, (b) at least one member selected from the group consisting of methyl methacrylate, ethyl methacrylate, methyl acrylate and ethyl acrylate, (c) acrylonitrile, (d) styrene, (e) a surfactant selected from the group consisting of sulfonates and sulfate derivatives, (f) a dispersant selected from the group consisting of aromatic formaldehyde condensation products and polycarboxylates and (g) a crosslinking agent; (2) from 80 to 90 parts by weight of a magnetic powder; and (3) from 1 to 10 parts by weight of an internal lubricant.