Dispenser for metering proportionate increments of polymerizable materials

Claim 1

Filled dispenser for simultaneously dispensing increments of extrudable materials that polymerize when mixed, while storing unused portions for later use, said dispenser having no internal valve and comprising: a body formed with a tubular cavity and an extrusion outlet at one end of said cavity, a piston slidably mounted within said cavity, said cavity containing between said piston and said outlet (a) at least two extrudable materials that polymerize when mixed together, each extending over the length of said cavity from said piston toward said outlet, and (b) at least one extrudable barrier layer disposed in separating relationship between said polymerizable materials, the material of said barrier layer being insoluble in each of said polymerizable materials while being dispersible in a mixture of them, said polymerizable materials and the material of the barrier layer having sufficiently equivalent rheologies at the temperature at which they are to be extruded from said dispenser to avoid substantial intermixing until after said polymerizable materials emerge from said outlet, and to permit removal of increments of said polymerizable materials from said dispenser without causing clogging of said outlet by the unused portion of said polymerizable materials remaining within said dispenser.