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Abstract

The disclosure relates to a novel and highly superior filter media formed of random-laid, lignin-containing fibers, and to a process for manufacture of the filter media. The process involves selection of lignin-containing fiber source, having a lignin content of at least about 10% and thermomechanically pulping the fiber source under temperature/pressure conditions of 300.degree. F.-350.degree. F./50 psig-120 psig and a refiner energy utilization of about 8-35 HPD/ADT. The thermomechanically produced fibers are characterized by a high degree of stiffness, and an extremely smooth surface free of fine fibril formation and thus substantially non-self-bonding. An improved filter media is formed by a random lay-up of the lignin-containing fibers, typically with selected other pulp fibers having technical characteristics suitable for filter media utilization. Suitable lignin-containing fiber, produced under conditions of the invention, may be substituted with minimum effort for conventional technical fibers utilized in furnishes intended for filter media production. The new filter media is characterized by exceptionally high bulk and void volume-two highly critical characteristics of filter media. The result ing product provides equal or superior product performance at significant reductions in production cost and/or exceptional improvement in performance at equivalent production cost.

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First Claim