Filter medium and breather filter structure

A method of filtering a heated fluid, the method comprises the steps of:

• (a) passing a mobile fluid phase containing a contaminant through a filter medium, the medium having a thickness of about 0.2 to 50 mm, the medium comprising a thermally bonded sheet, the sheet comprising:
• (i) about 20 to 80 wt % of a bicomponent binder fiber comprising polyolefin, polyester, or both, the bicomponent binder fiber having a first component with a melting point and a second component with a lower melting point, wherein the second component has a melting point below 205° C., the fiber having a fiber diameter of about 5 to 50 micrometers and a fiber length of about 0.1 to 15 cm;
• and
• (ii) about 20 to 80 wt % of a glass fiber having a fiber diameter of about 0.1 to 30 micrometers and an aspect ratio of about 10 to 10,000;
• wherein the media has a solidity of about 2 to 25%,
• a basis weight of about 10 to 1000 g-m−2,
• a pore size of about 0.5 to 100 micrometers and
• a permeability of about 5 to 500 ft-min−1,
• the mobile fluid phase having a temperature greater than the melting point of the second component;
• and
• (b) removing the contaminant.