Importance

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Abstract

A pleated paper filter element (10) has a fluid-permeable foamed-plastic shield (16) formed on one of its faces to firmly and accurately position the adjacent folds of filter media. The shield (16) is formed in situ and bonds to the filter media without the use of an intermediate adhesive so as to form a unitary structure. A method of making such a filter involves disposing a foamable liquid plastic (34) near a pleated paper filter unit and foaming the plastic. Prior to solidification, the plastic is effective to bond directly to the filter media. A mold (22) for making such a filter element includes a receptacle (28) for receiving a quantity of liquid plastic and a filter unit and for holding them in the proper relation while the plastic is foamed. The mold receptacle includes projections (30) which form perforations (18) in the solidified plastic and which provide for fluid flow communication through the filter element. The plastic may be of the open-cell fluid-permeable type to permit fluid flow communication through the shield to the filter element.

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First Claim