Microporous elastomeric film/nonwoven breathable laminate and method for making the same

A breathable laminate comprising:

• an oriented microporous relaxed unbiased film layer (10C) comprising an elastomeric polymer resin and at least 30% by weight of a filler having a particle size that contributes to pore formation and coated with a stearic acid,
• the relaxed unbiased film layer formed from an unstretched filled film (10A) having an original length and a stretched length (10B), said relaxed unbiased film layer including a permanent elongation of about 3 times the original length,
• and said relaxed unbiased film layer (10C) capable of having a room-temperature biased length that is at least about one and a half times said relaxed unbiased film layer length and a release length, upon release of a biasing force of no more than one and one quarter of the relaxed unbiased film layer length, having a water vapor transmission rate of at least about 1,000 g/m.sup.2 -24 hrs;
• and
• wherein said elastomeric polymer includes at least one of a) ethylene-propylene elastomer blends, b) ethylene copolymers, c) block copolymers including styrene, d) terpolymers of ethylene and propylene, e) molecular blends of at least two polymers of propylenes or polymers of propylene with ethylene, f) ethylene vinyl acetate, g) ethylene-normal butyl acrylate, or h) ethylene methyl acrylate;
• and
• at least one support layer bonded to said film layer.

A breathable laminate comprising:

• an oriented microporous relaxed unbiased film layer (10C) comprising an elastomeric polymer resin and at least 30% by weight of a filler having a particle size that contributes to pore formation,
• the relaxed unbiased film layer formed from an unstretched filled film (10A) having an original length and a stretched length (10B), said relaxed unbiased film layer including a permanent elongation of at least about 1.5 times the original length,
• and said relaxed unbiased film layer (10C) capable of having a room-temperature biased length that is at least about one and a half times said relaxed unbiased film layer length and a release length, upon release of a biasing force of no more than one and one quarter of the relaxed unbiased film layer length, having a water vapor transmission rate of at least about 1,000 g/m.sup.2 -24 hrs,
• wherein said elastomeric polymer includes at least one of a) ethylene-propylene elastomer blends, b) ethylene copolymers, c) block copolymers including styrene, d) terpolymers of ethylene and propylene, e) molecular blends of at least two polymers of propylenes or polymers of propylene with ethylene, f) ethylene vinyl acetate, g) ethylene-normal butyl acrylate, or h) ethylene methyl acrylate;
• and
• at least one support layer bonded to said film layer.

A breathable laminate comprising:

• an oriented microporous relaxed unbiased film layer (10C) comprising an elastomeric polymer resin and at least 30% by weight of a filler having a particle size that contributes to pore formation,
• the relaxed unbiased film layer formed from an unstretched filled film (10A) having an original length and a stretched length (10B), said relaxed unbiased film layer including a permanent elongation of about 3 times the original length,
• and said relaxed unbiased film layer (10C) capable of having a room-temperature biased length that is at least about one and a half times said relaxed unbiased film layer length and a release length, upon release of a biasing force of no more than one and one quarter of the relaxed unbiased film layer length, having a water vapor transmission rate of at least about 1,000 g/m.sup.2 -24 hrs,
• wherein said elastomeric polymer includes at least one of a) ethylene-propylene elastomer blends, b) ethylene copolymers, c) block copolymers including styrene, d) terpolymers of ethylene and propylene, e) molecular blends of at least two polymers of propylenes or polymers of propylene with ethylene, f) ethylene vinyl acetate, g) ethylene-normal butyl acrylate, or h) ethylene methyl acrylate;
• and
• at least one support layer bonded to said film layer.

A process for forming a breathable laminate comprising:

• providing a filled film layer comprising at least 30% by weight of a filler having a particle size that contributes to pore formation and an elastomeric polymer material having an original length and capable of having a stretched length wherein, said elastomeric polymer includes at least one of a) ethylene-propylene elastomer blends, b) ethylene copolymers, c) block copolymers including styrene, d) terpolymers of ethylene and propylene, e) molecular blends of at least two polymers of propylenes or polymers of propylene with ethylene, f) ethylene vinyl acetate, g) ethylene-normal butyl acrylate, or h) ethylene methyl acrylate;
• stretching said filled film to produce a microporous film;
• relaxing said stretched microporous film to impart a permanent elongation of at least 1.5 times the original length, said relaxed film capable of having a room-temperature biased length that is at least about one and half times said relaxed unbiased film layer length and a release length, upon release of a biasing force of no more than one and one quarter of the relaxed unbiased film layer length, having a water vapor transmission rate of at least about 1.000 g/m.sup.2 -24 hrs;
• and
• bonding at least one support layer to said microporous film to form a laminate.