US4215682A — Melt-blown fibrous electrets

Claim 1

Independent Claim 71 words

A fibrous web electret comprising melt-blown fibers prepared by extruding molten fiber-forming material through orifices into a high-velocity gaseous stream where the extruded material is drawn out into fibers and solidified in the fibrous form, said fibers having electrically charged particles and a persistent electric charge that is useful to enhance filtering properties of the web, said charge having a half-life of at least one week in a room-temperature, 100-percent-relative-humidity environment.

Claim 2

Dependent Claim 71 words

A fibrous web electret comprising melt-blown fibers prepared by extruding molten fiber-forming material through orifices into a high-velocity gaseous stream where the extruded material is drawn out into fibers and solidified in the fibrous form, said fibers having electrically charged particles and a persistent electric charge that is useful to enhance filtering properties of the web, said charge having a half-life of at least one week in a room-temperature, 100-percent-relative-humidity environment.

Claim 3

Dependent Claim 14 words

A fibrous web electret of claim 1 in which said melt-blown fibers comprise polypropylene.

Claim 4

Dependent Claim 20 words

A fibrous web electret of claim 1 in which said melt-blown fibers average less than about 25 micrometers in diameter.

Claim 5

Dependent Claim 17 words

A fibrous web electret of claim 1 which further includes staple fibers interspeersed with said melt-blown fibers.

Claim 6

Dependent Claim 15 words

A fibrous web electret of claim 1 which further includes particles dispersed in the web.

Claim 7

Dependent Claim 32 words

Filter apparatus comprising support structure for supporting a filter web across a stream of fluid that is to be filtered, and a fibrous web electret of claim 1 supported by said structure.

Claim 8

Dependent Claim 56 words

A respirator comprising support structure for mounting the respirator on a person, and filter means through which air is drawn from the ambient environment to the mouth and nose of a person wearing the respirator, said filter means including a fibrous web electret of claim 1 disposed so as to filter air drawn into the respirator.

Claim 9

Dependent Claim 43 words

A respirator of claim 7 which comprises a cup-like member adapted to fit over the mouth and nose of a person wearing the respirator, and in which at least a layer of said cup-like member comprises the fibrous web electret of claim 1.

Claim 10

Dependent Claim 92 words

A fibrous web electret comprising a coherent mass of randomly intertangled melt-blown microfibers which average less than 10 micrometers in diameter, said microfibers being prepared by extruding molten fiber-forming material through orifices into a high-velocity gaseous stream where the extruded material is drawn out into fibers and solidified in the fibrous form, said microfibers having electrically charged particles in an amount sufficient to provide a persistent electric charge of at least 10 -8 coulombs per gram of said microfibers, with a half-life of at least six months in a room-temperature, 100-percent-relative-humidity environment.

Claim 11

Dependent Claim 92 words

A fibrous web electret comprising a coherent mass of randomly intertangled melt-blown microfibers which average less than 10 micrometers in diameter, said microfibers being prepared by extruding molten fiber-forming material through orifices into a high-velocity gaseous stream where the extruded material is drawn out into fibers and solidified in the fibrous form, said microfibers having electrically charged particles in an amount sufficient to provide a persistent electric charge of at least 10 -8 coulombs per gram of said microfibers, with a half-life of at least six months in a room-temperature, 100-percent-relative-humidity environment.

Claim 12

Dependent Claim 14 words

A fibrous web electret of claim 9 in which said melt-blown microfibers comprise polypropylene.

Claim 13

Dependent Claim 17 words

A fibrous web electret of claim 9 which further includes staple fibers interspersed with said melt-blown fibers.

Claim 14

Dependent Claim 15 words

A fibrous web electret of claim 9 which further includes particles dispersed in the web.

Claim 15

Dependent Claim 32 words

Filter apparatus comprising support structure for supporting a filter web across a stream of fluid that is to be filtered, and a fibrous web electret of claim 9 supported by said structure.

Claim 16

Dependent Claim 56 words

A respirator comprising support structure for mounting the respirator on a person, and filter means through which air is drawn from the ambient environment to the mouth and nose of a person wearing the respirator, said filter means including a fibrous web electret of claim 9 disposed so as to filter air drawn into the respirator.

Claim 17

Dependent Claim 43 words

A respirator of claim 14 which comprises a cup-like member adapted to fit over the mouth and nose of a person wearing the respirator, and in which at least a layer of said cup-like member comprises the fibrous web electret of claim 9.

Claim 18

Independent Claim 110 words

A method for forming a melt-blown fibrous web electret comprising (1) extruding molten fiber-forming material that exhibits a volume resistivity of at least 10 14 ohm-centimeters through a plurality of orifices into a high-velocity gaseous stream where the extruded material is attenuated to form a stream of fibers; (2) bombarding electrically charged particles at said stream of fibers as the fibers issue from the orifices wherein the fibers are both near the source of the electrically charged particles and are in a molten or near-molten state; and (3)collecting said fibers at a point sufficiently remote from the orifices for the fibers to have cooled to a solid fibrous shape-retaining form.

Claim 19

Independent Claim 110 words

A method for forming a melt-blown fibrous web electret comprising (1) extruding molten fiber-forming material that exhibits a volume resistivity of at least 10 14 ohm-centimeters through a plurality of orifices into a high-velocity gaseous stream where the extruded material is attenuated to form a stream of fibers; (2) bombarding electrically charged particles at said stream of fibers as the fibers issue from the orifices wherein the fibers are both near the source of the electrically charged particles and are in a molten or near-molten state; and (3)collecting said fibers at a point sufficiently remote from the orifices for the fibers to have cooled to a solid fibrous shape-retaining form.

Claim 20

Dependent Claim 25 words

A method of claim 16 in which staple fibers are introduced into said stream of fibers after the stream has been bombarded with charged particles.

Claim 21

Dependent Claim 24 words

A method of claim 16 in which particles are introduced into said stream of fibers after the stream has been bombarded with charged particles.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1983-08-05	1984-02-04	1984-08-05	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1987-08-05	1988-02-04	1988-08-05	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1991-08-05	1992-02-04	1992-08-05	$7700.00	Window Closed / Lapsed

Melt-blown fibrous electrets

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