Composite diaphragm for diaphragm pumps

Abstract

A pump diaphragm that is composed of two different shore-hardness materials of the same base polymer. The diaphragm includes a strong layer that will withstand hydraulic pressures and one or more soft layers that can be shaped into desirable sealing configurations. The diaphragm is constructed by first injecting a first thermoplastic material, with a relatively lower percentage of rubber filler, into a mold cavity and allowing the first material to cure. The hardened first material is then placed into a second mold cavity. A second thermoplastic material which contains the same base polymer but a relatively higher percentage of rubber filler is then injected into the second cavity. The first and second material utilize the same base polymer and thus will have the same melt temperature, as well as a strong propensity to bond to each other when molten. The second material is introduced to the cavity at a temperature that melts the interface of the first material. As the second material and the interface hardness, the two layers have become chemically welded together. The second cavity gives shape to the sealing areas of the diaphragm.

Dependencies are inferred from the claim text.