Breathable non-woven composite viral penetration barrier fabric and fabrication process

A non-woven composite fabric comprising:

• a polypropylene microporous film having at least one film surface bonded to a layer of non-woven thermoplastic polymer, said film and layers being bonded at multiple spaced-apart locations;
• said layers and microporous film being joined by ultrasonic point bonding;
• said composite fabric meeting the requirements of ASTM ES22-92 by providing a barrier to passage of biological liquid as defined when the composite fabric is subjected to contact with synthetic blood at zero psi for five synthetic blood contact for fifty-four minutes;
• the composite fabric meeting the requirements of ASTM ES22-92 by providing a barrier to viral penetration when the composite fabric is subject to contact with .phi.X174 bacteriophage suspension at a titer of 10.sup.8 PFU/mL for 5 minutes with no applied pressure, 1 minute at 13.8 kPa (2.0 PSIG), and 54 minutes with no applied pressure;
• and
• said composite fabric exhibiting no visible penetration of the synthetic blood;
• said composite fabric having a moisture or vapor transmission rate of greater than about 450 grams per square meter for twenty-four hours at about 75 degrees F and about 65% relative humidity;
• and
• said woven composite fabric having a breaking strength of at least about 14 pounds.

A process for forming a thermally bonded non-woven composite fabric having a moisture or vapor transmission rate of greater than about 450 grams per square meter for 24 hours at about 75 degrees F and about 65 percent relative humidity, said fabric meeting the requirements of ASTM ES21-92 by providing a barrier to passage of biological liquid when the composite fabric is subjected to contact with synthetic blood at 0 psi for 5 minutes followed by synthetic blood contact at 2 psi (13.6 kpa) for 1 minute follwed by synthetic blood contact at 0 psi for 54 minutes, said composite fabric exhibiting no visible penetration of the synthetic blood;

• and said composite fabric having a breaking strength of at least 14 pounds per inch;
• the composite fabric meeting the requirements of ASTM ES22-92 by providing a barrier to viral penetration when the composite fabric is subject to contact with .phi.X174 bacteriophage suspension at a titer of 10.sup.8 PFU/mL for 5 minutes with no applied pressure, 1 minute at 13.8 kPa (2.0 PSIG), and 54 minutes with no applied pressure;
• and comprising:
• unwinding and contacting at least one continuous thermoplastic non-woven web to at least one side of a continuous polypropylene microporous film;
• continuously transporting said contacted web and film through an ultrasonic point bonding zone;
• thermally bonding the webs and film at multiple spaced-apart locations;
• said bonding having a dwell time sufficient to thermally bond while avoiding burn-through degradation of the film and webs;
• and
• forming the thermally bonded non-woven composite fabric.

A non-woven composite fabric comprising:

• a polypropylene microporous film having polygonal cells with average greatest dimensions of about 5 to about 30 microns and interconnecting pores between the cells having average diameters of about 0.2 to about 20 microns, the film having at least one film surface bonded to a layer of non-woven thermoplastic polymer, said film and layers being bonded at multiple spaced-apart location;
• said layers and microporous film being joined by ultrasonic point bonding;
• said composite fabric is subjected to contact with synthetic blood at zero psi for five minutes followed by synthetic blood contact at 2 psi for one minute followed by zero psi synthetic blood contact for fifty-four minutes;
• the composite fabric providing a barrier to viral penetration when the composite fabric is subject to contact with .phi.X174 bacteriophage suspension at a liter of 10.sup.8 PFU/MI for 5 minutes with no applied pressure, 1 minute at 13.8 Kpa (2.0 PSIG), and 54 minutes with no applied pressure;
• and
• said composite fabric exhibiting no visible penetration of the synthetic blood;
• said composite fabric having a moisture or vapor transmission rate of greater than about 450 grams per square meter for twenty-four hours at about 75.degree. F. and about 65% relative humidity;
• and
• said woven composite fabric having a breaking strength of at least about 14 pounds.