초록 ▼

A fluid filter is formed by producing an air laid nonwoven batt comprising a randomly arranged mixture of thermoplastic fibers and fibers which are not thermoplastic. The batt is then cut into sections, and portions of the batt are heated to a temperature sufficient to partially fuse the fibers, the

A fluid filter is formed by producing an air laid nonwoven batt comprising a randomly arranged mixture of thermoplastic fibers and fibers which are not thermoplastic. The batt is then cut into sections, and portions of the batt are heated to a temperature sufficient to partially fuse the fibers, thereby increasing the density of the portion of the batt which is heated. Accordingly, a gradient density filter may be produced having a progressively greater density from the fluid receiving side to the fluid expressing side, so that larger particles are trapped at the fluid receiving side and progressively smaller particles are trapped as the fluid flows through the media, with the finest particles being trapped at the fluid expressing side.

대표청구항 ▼

Method of forming a fluid filter comprising the steps of forming a nonwoven batt comprising a randomly arrayed mixture of a thermoplastic material and fibers which are not thermoplastic, shaping said batt into the desired shape of a fluid filter, and heating only a selected portion of said batt whil

Method of forming a fluid filter comprising the steps of forming a nonwoven batt comprising a randomly arrayed mixture of a thermoplastic material and fibers which are not thermoplastic, shaping said batt into the desired shape of a fluid filter, and heating only a selected portion of said batt while molding the latter into said desired filter shape and while maintaining the rest of said batt other than the selected portion at a temperature less than the temperature of said selected portion to thereby permit softening and fusing of the thermoplastic material at said selected portion to thereby increase the stiffness and decrease the permeability of said selected portion, said step of heating and molding said batt being initiated only after formation of the batt has been completed.