Process for making a porous filter element, porous filter elements made thereby, and filter devices including them

A process for making a filter element comprising a filter membrane having a strip of thermoplastic polymer material laminated thereto, the method comprising:

• providing a sheet of filter membrane having a first surface and an opposed second surface;
• providing a strip of thermoplastic polymer material having a first surface and an opposed second surface;
• contacting the first surface of the strip of thermoplastic polymer material with the first surface of the filter membrane;
• and
• softening the strip of thermoplastic polymer material at at least its first surface by irradiation with laser radiation without softening the sheet of filter membrane at the position at which the strip of thermoplastic polymer is contacted, and such that the temperature of the strip of thermoplastic material at the first surface thereof remains at least 50 ° C. less than the softening point of the material of the filter membrane while they are in contact with one another;
• such that the softened polymer material of the first surface of the strip of thermoplastic polymer material bonds to the first surface of the filter membrane upon hardening,
• wherein the melting point of the thermoplastic polymer material is at least 50° C. lower than the softening point of the material of the filter membrane,
• wherein the process is performed without contacting both the second surface of the strip of thermoplastic material and the second surface of the filter membrane within 2 cm of the strip of thermoplastic polymer material with a process equipment member while the first surface of the strip of thermoplastic polymer material is in a softened state, and
• wherein the process is a continuous roll-to-roll process, in which the sheet of polymeric filter membrane is dispensed from a first roll, and the filter membrane having the strip of thermoplastic polymer material laminated thereto is collected on a second roll.