Continuous production of tubular modular filter elements using nonwoven webs from thermoplastic fibers and products

Claim 1

A seamless tubular filter element comprising a tubular foraminous core having superimposed and supported thereon in the form of a cylinder a flexible wound layer of randomly-oriented heterogeneously intertwined spun fibers less than 10 μin diameter and having an open area of at least 60%, laid down on the core and having end caps at each end of the cylinder, the end caps having a circumferential relatively narrow slot about the periphery of their inside face whose width at the inside face is less than the thickness of the end of the core plus the folded-over thickness of the layer; the layer having at each end a flexible selvage extending beyond the end of the core and folded over the end and extending into the interior of the core, with the folded-over portion sealingly compressed in the slot between the core end and the side walls of the slot, and thereby attached to the end caps in a leak-tight seal.