Microporous materials suitable as substrates for printed electronics

An electronic device comprising:

• (I) a substrate comprising a microporous material comprising:
• (a) a polyolefin matrix comprising 30 to 80 weight percent high density polyolefin,
• (b) finely divided particulate filler distributed throughout the matrix, said particulate comprising 10 to 30 weight percent or less of calcium carbonate, and
• (c) at least 35 percent by volume of a network of interconnecting pores communicating throughout the microporous material,
• wherein the microporous material has a density ranging from 0.5 to 0.8 g/cc, a Sheffield smoothness of less than or equal to 40, an air flow rate of 1000 or more Gurley seconds, and MD stress at 1% strain of greater than or equal to 200 psi;
• and
• (II) a conductive ink appended to at least a portion of a surface of the substrate (I).

A microporous sheet material comprising:

• (a) a polyolefin matrix comprised of a matrix composition comprising 30 to 80 weight percent high density polyolefin,
• (b) finely divided particulate filler distributed throughout the matrix, said particulate comprising 10 to 30 weight percent or less of calcium carbonate, and
• (c) a network of interconnecting pores communicating throughout the microporous material,
• wherein the microporous sheet material is prepared by a method comprising:
• (i) forming a mixture comprising the polyolefin (a), inorganic filler (b), and a processing plasticizer composition;
• (ii) extruding the mixture to form a continuous sheet having a processing plasticizer composition content ranging from 40 to 65 weight percent based on weight of the continuous sheet;
• and
• (iii) contacting the continuous sheet with an extraction fluid composition to extract the processing plasticizer composition from the continuous sheet to form the microporous sheet material,
• wherein the microporous sheet material has a density ranging from 0.5 to 0.8 g/cc, a Sheffield smoothness of less than or equal to 40, an air flow rate of 1000 or more Gurley seconds, and MD stress at 1% strain of greater than or equal to 200 psi.