초록

A method and apparatus of producing a filter medium of a relatively strong substrate and a fibrous felt layer bonded to the substrate by needle punching the felt through the substrate and fusing the fibers protruding through the perforations to the substrate and each other.

대표청구항 ▼

A filter medium comprising a relatively strong substrate, said substrate being a laminate of a spun bonded material and a melt blown plastic material, a fibrous thermoplastic felt layer on the spun bonded surface of the substrate upstream to the flow of fluid to be filtered, means bonding the fibrou

A filter medium comprising a relatively strong substrate, said substrate being a laminate of a spun bonded material and a melt blown plastic material, a fibrous thermoplastic felt layer on the spun bonded surface of the substrate upstream to the flow of fluid to be filtered, means bonding the fibrous felt layer to the substrate by fibers needle punched through the fibrous felt layer and the substrate and fused on the downstream surface of the substrate, filtration perforations in the substrate formed by the needle punching and fibers protruding through the perforations on the melt down downstream surface of the substrate and fused on said downstream surface, the spun bonded material imparting the necessary strength, stability and integrity to the filter medium and having the ability to deform and retain discrete defined perforations formed therein for the free passage of fluids while preventing the flow therethrough of oversized particles, the fibrous felt layer collecting, trapping and retaining dirt and debris on the upstream surface of the substrate and the melt blown material and protruding fibers providing a downstream layer capable of retaining and filtering fine particles which pass through the perforations.