Medical use venting filter

A filter comprising:

• (i) a layer comprising at least one poly(tetrafluoroethylene) membrane;
• and
• (ii) a layer comprising at least two polyester nonwoven layers, the polyester nonwoven layers comprised of a first polyester layer and a second polyester layer,
• wherein the first polyester layer is in bonded contact with the poly(tetrafluoroethylene) membrane and possesses a melting point from about 95° C. to about 180° C., and wherein the second polyester layer is in bonded contact with the first polyester layer and has a melting point from about 220° C. to about 265° C.

A process for laminating (i) a fluoropolymer membrane and (ii) a bonded layer, the process comprising:

• a. applying the bonded layer to the fluoropolymer membrane, wherein the bonded layer comprises at least two air-permeable thermoplastic polymeric layers, the air-permeable thermoplastic polymeric layers comprised of a first polymeric layer having a melting point from about 95° to about 180° C., and a second polymeric layer having a melting point from about 220° to about 265° C., thereby contacting the first polymeric layer of the bonded layer with the fluoropolymer membrane, on a surface having a temperature from about 50° to about 260° C. to form a combined bonded layer and fluoropolymer structure;
• and
• b. subjecting the combined bonded layer and fluoropolymer structure to a temperature of about 140° C. to about 210° C., while compressing at a pressure from about 0.05 to about 0.4 MPa, and while exerting an elongation tension on the combined bonded layer and fluoropolymer structure from about 0.05 to about 0.3 Newtons to form a composite fluoropolymer-thermoplastic polymeric filter structure;
• c. and cooling the resulting fluoropolymer-thermoplastic polymeric composite filter structure.