3m Innovative Properties Company

John D Stelter

Andrew R Fox

Michael R Berrigan

Seyed Abolhassan Angadjivand

John M Brandner

Timothy J Lindquist

Eric M Moore

James E Springett

Sian F Fennessey

Matthew T Scholz

Francis E Porbeni

Kevin D Landgrebe

Jay M Jennen

Korey W Karls

William T Fay

Marvin E Jones

Jonathan M Lise

Patrick J Hager

Douglas C Sundet

Kevin M Eliason

Troy K Ista

Liming Song

Thomas J Reid

Scott J Tuman

Nathan E Schultz

Zhiqun Zhang

Fuming B Li

Bradley W Eaton

Zackary J Becker

John M Sebastian

Yifan Zhang

Pamela A Percha

Ignatius A Kadoma

Bryan L Gerhardt

Sachin Talwar

Cordell M Hardy

Ruth A Ebbens

Korey W Karis

Timothy J Diekmann

The present disclosure relates to multi-layer composite articles including at least two nonwoven web layers. Each or the layers may be a spunbonded web, and each may include biodegradable materials. The multi-layered composites of the present disclosure are particularly well suited for air filtration, as they can combine a high dust holding capacity with sufficient strength, dimensional stability, and a relatively low pressure drop.

Multi-layer, biodegradable composites for air filtration

A flat-fold respirator is made from a stiff filtration panel joined to the remainder of the respirator through at least one line of demarcation. The panel contains a porous monocomponent monolayer nonwoven web that contains charged intermingled continuous monocomponent polymeric fibers of the same polymeric composition and that has sufficient basis weight or inter-fiber bonding so that the web exhibits a Gurley Stiffness greater than 200 mg and the respirator exhibits less than 20 mm HO pressure drop. The respirator may be formed without requiring additional stiffening layers, bicomponent fibers, or other reinforcement and can be flat-folded for storage. Scrap from the manufacturing process may be recycled to make additional stiff filtration panel web.

Flat-fold respirator with monocomponent filtration/stiffening monolayer

Spunbonded electret webs comprising polylactic acid fibers, in which at least some of the polylactic acid fibers are meltspun, drawn, charged fibers that include charging additive; and, methods of making such fibers and webs.

Spunbonded web comprising polylactic acid fibers

Dimensionally stable nonwoven fibrous webs include a plurality of fibers formed from one or more thermoplastic polyesters and an antishrink additive, preferably in an amount greater than 0% and no more than 10% by weight of the web. The webs have at least one dimension which decreases by no greater than 12% in the plane of the web when heated to a temperature above a glass transition temperature of the fibers. The webs may be used as wipes.

Dimensionally stable nonwoven fibrous webs, and methods of making and using the same

Dimensionally stable nonwoven fibrous webs include a multiplicity of continuous fibers formed from one or more thermoplastic polyesters and polypropylene in an amount greater than 0% and no more than 10% by weight of the web. The webs have at least one dimension which decreases by no greater than 10% in the plane of the web when heated to a temperature above a glass transition temperature of the fibers. When the thermoplastic polyester is selected to include aliphatic and aromatic polyesters, a spunbond process may be used to produce substantially continuous fibers that exhibit molecular orientation. When the thermoplastic polyester is selected from aliphatic polyesters, a meltblown process may be used to produce discontinuous fibers that do not exhibit molecular orientation. The webs may be used as articles for filtration, sound absorption, thermal insulation, surface cleaning, cellular growth support, drug delivery, personal hygiene, medical apparel, or wound dressing.

Dimensionally stable nonwoven fibrous webs and methods of making and using the same

Dimensionally stable nonwoven fibrous webs include a multiplicity of continuous fibers formed from one or more thermoplastic polyesters and polypropylene in an amount greater than 0% and no more than 10% by weight of the web. The webs have at least one dimension which decreases by no greater than 10% in the plane of the web when heated to a temperature above a glass transition temperature of the fibers. A spunbond process may be used to produce substantially continuous fibers that exhibit molecular orientation. A meltblown process may be used to produce discontinuous fibers that do not exhibit molecular orientation. In some embodiments, the fibers comprise a viscosity modifier and/or an anionic surfactant. The webs may be used as articles for filtration, sound absorption, thermal insulation, surface cleaning, cellular growth support, drug delivery, personal hygiene, medical apparel, or wound dressing.

Process of making dimensionally stable nonwoven fibrous webs

Dimensionally stable nonwoven fibrous webs include a multiplicity of continuous fibers formed from one or more thermoplastic polyesters and polypropylene in an amount greater than 0% and no more than 10% by weight of the web. The webs have at least one dimension which decreases by no greater than 10% in the plane of the web when heated to a temperature above a glass transition temperature of the fibers. A spunbond process may be used to produce substantially continuous fibers that exhibit molecular orientation. A meltblown process may be used to produce discontinuous fibers that do not exhibit molecular orientation. The webs may be used as articles for filtration, sound absorption, thermal insulation, surface cleaning, cellular growth support, drug delivery, personal hygiene, medical apparel, or wound dressing.

A method for making a bonded nonwoven fibrous web comprising 1) providing a nonwoven fibrous web that comprises oriented semicrystalline polymeric fibers, and 2) subjecting the web to a controlled heating and quenching operation that includes a) forcefully passing through the web a fluid heated to at least the onset melting temperature of said polymeric material for a time too short to wholly melt the fibers, and b) immediately quenching the web by forcefully passing through the web a fluid at a temperature at least 50&#xb0; C. less than the Nominal Melting Point of the material of the fibers. The fibers of the treated web generally have i) an amorphous-characterized phase that exhibits repeatable softening (making the fibers softenable) and ii) a crystallite-characterized phase that reinforces the fiber structure during softening of the amorphous-characterized phase, whereby the fibers may be autogenously bonded while retaining orientation and fiber structure. Apparatus for carrying out the method can comprise 1) a conveyor for conveying a web to be treated, 2) a heater mounted adjacent a first side of the conveyor and comprising a) a chamber having a wall that faces the web, b) one or more conduits through which a heated gas can be introduced into the chamber under pressure and c) a slot in said chamber wall through which heated gas flows from the chamber onto a web on the conveyor, 3) a source of quenching gas downweb from the heater on the first side of the conveyor, the quenching gas having a temperature substantially less than that of the heated gas, 4) gas-withdrawal mean disposed on the second side of the conveyor opposite from the heater, the gas-withdrawal means having a portion in alignment with the slot so as to draw heated gas from the slot through the web and also a portion downweb from the slot in alignment with the source of quenching gas so as to draw the quenching gas through the web to quench the web. Flow restrictor means is preferably disposed on the second side of the conveyor in the path of at least one of the heated gas and the quenching gas so as to even the distribution of the gas through the web.

Bonded nonwoven fibrous webs comprising softenable oriented semicrystalline polymeric fibers and apparatus and methods for preparing such webs

A method for making a bonded nonwoven fibrous web comprising extruding melt blown fibers of a polymeric material, collecting the melt blown fibers as an initial nonwoven fibrous web, annealing the initial nonwoven fibrous web with a controlled heating and cooling operation, and collecting the dimensionally stable bonded nonwoven fibrous web is described. The bonded nonwoven fibrous web shrinkage is typically less than 4 percent relative to the initial nonwoven fibrous web.

Dimensionally stable bonded nonwoven fibrous webs

A nonwoven fibrous web comprising a matrix of continuous meltspun fibers bonded to a coherent self-sustaining form, and separately prepared microfibers dispersed among the meltspun fibers. The microfibers may have median diameters less than one or two micrometers. A method for preparing such a nonwoven fibrous web comprises establishing a stream of continuous oriented meltspun fibers having a longitudinal axis, establishing a stream of meltblown microfibers that exit a meltblowing die at a point near the stream of meltspun fibers, the meltblown stream being aimed to merge with the meltspun stream and having a longitudinal axis that forms an angle of between 0 and 90 degrees to the longitudinal axis of the meltspun stream, capturing the meltblown fibers in the stream of meltspun fibers, and collecting the merged stream as a web on a collector spaced near the intersection point of the meltspun and meltblown streams.

Method of manufacturing a fibrous web comprising microfibers dispersed among bonded meltspun fibers

A molded respirator is made from a monocomponent monolayer nonwoven web containing a bimodal mass fraction/fiber size mixture of intermingled continuous monocomponent polymeric microfibers and larger size fibers of the same polymeric composition. The respirator is a cup-shaped porous monocomponent monolayer matrix whose matrix fibers are bonded to one another at least some points of fiber intersection. The matrix has a King Stiffness greater than 1 N. The respirator may be formed without requiring stiffening layers, bicomponent fibers, or other reinforcement in the filter media layer.

Process of making a molded respirator

A molded respirator is made from a monocomponent monolayer nonwoven web of continuous charged monocomponent meltspun partially crystalline and partially amorphous oriented fibers of the same polymeric composition that have been bonded to form a coherent and handleable web which further may be softened while retaining orientation and fiber structure. The respirator is a cup-shaped porous monocomponent monolayer matrix whose matrix fibers are bonded to one another at at least some points of fiber intersection. The matrix has a King Stiffness greater than 1 N. The respirator may be formed without requiring stiffening layers, bicomponent fibers, or other reinforcement in the filter media layer.

Molded monocomponent monolayer respirator

A pleated filter is made from a monocomponent monolayer nonwoven web of continuous monocomponent meltspun partially crystalline and partially amorphous oriented fibers of the same polymeric composition that are bonded to form a coherent and handleable web having a Gurley Stiffness of at least 100 mg and which further may be softened while retaining orientation and fiber structure. Rows of pleats are formed in the nonwoven web, and the web is cut to a desired size and shape to provide a pleated filter element containing a self-supporting porous monocomponent monolayer matrix of fibers bonded to one another at least some points of fiber intersection and having an average initial submicron efficiency of at least 15% at a 1.52 meters/sec face velocity. The filter element is deformation resistant without requiring stiffening layers, bicomponent fibers, adhesive or other reinforcement in the filter media layer.

Pleated filter with monolayer monocomponent meltspun media

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St. Joseph Township, WI, United States of America

John D Stelter