Abstract: A process of producing composite sheet is presented, and the process comprises the steps of: (a) providing a plurality of metallic sheets; (b) bonding the metallic sheets with one another; and(c) finishing the bonded composite sheet that has a plurality of metallic layers. In comparison to conventional single type/solid piece of building material, the present invention results in a dramatic cost reduction in various building industry. With the up-to-date technology, the strength of metallic composite sheet remains within structural grade parameter and meets related specifications. Manufacturers are benefited from the cheaper metallic sheet in the composition while enjoying the same quality look of the outer layer. Furthermore, a structure of the composite sheet is also presented in the present invention.

Abstract: A multilayer film includes a plastic layer and an elastomeric layer. The plastic layer can contain a co-polyester of terepthalic acid, adipic acid and butanediol, and the elastomeric layer can contain a polyurethane elastomer. The plastic layer and/or the elastomeric layer can contain filler particles, and may be present as a bilayer laminate. The plastic layer and a filled elastomeric layer can also be combined with an unfilled elastomeric layer to form a tri-layer laminate. The multilayer films can provide breathable films with improved degradability, stretchability and recoverability, and tactile feel.

Abstract: Dielectric composite structures comprising interfaces possessing nanometer scale corrugated interfaces in interconnect stack provide enhances adhesion strength and interfacial fracture toughness. Composite structures further comprising corrugated adhesion promoter layers to further increase intrinsic interfacial adhesion are also described. Methods to form the nanometer scale corrugated interfaces for enabling these structures using self assembling polymer systems and pattern transfer process are also described.

Abstract: A breathable waterproof structure, made from a waterproof layer, mounted on an exterior wall side, that is a composite of a spun bonded non-woven sheet material with a resin layer on an interior surface of the sheet material; and a vent layer-forming member that is a corrugated spun bonded non-woven sheet material that is integrally attached to the waterproof layer by being multiply spot-adhered via the valleys of the corrugations and thereby generating the vent layer with a designated gap with the waterproof layer.

Abstract: A light-weight mirror blank assembly, having at least one sheet of corrugated material; and at least one face sheet in intimate contact with a surface of the sheet of corrugated material forming the light-weight mirror blank assembly. The light-weight mirror blank assembly has an areal density less than an equivalent blank assembly having a solid support structure for supporting a mirrored surface.

Abstract: A wall element, comprising two outer layers extending at least substantially parallel to each other, between which two or more intermediate layers are provided, characterized in that said intermediate layers extends between the outer layers in a zigzag fashion, wherein the intermediate layers are arranged in a nested fashion.

Abstract: A structural panel comprised of a plurality of distinct layers of cylindrical foam elements each covered with a fiber-reinforced composite material. The cylindrical foam elements are arranged in layers such that the elements of adjacent layers are arranged non-parallel to one another. A pair of facesheets are secured to opposing surfaces of the cylindrical foam elements. The structural panel is high in strength, structural stiffness, and yet relatively low in weight, and is suitable for a variety of aerospace and other applications.

Abstract: A box for shipping temperature sensitive or perishable goods made from a double walled combined web having an inside barrier layer, a first paper liner bonded to the inside barrier layer, a first paper flute medium bonded to the first paper liner, an outside barrier layer, a second paper liner bonded to the outside barrier layer, a second paper flute medium bonded to the second paper liner, and a sandwich of a barrier layer bonded between third and fourth paper liners. The flute mediums are bonded, respectively, to the third and fourth paper liners.

Abstract: Absorbent article comprising a liquid-impermeable cover sheet, a liquid-permeable cover sheet, and an absorbent body between the liquid-impermeable cover sheet and the liquid-permeable cover sheet. Any one or all of the liquid-impermeable cover sheet, the liquid-permeable cover sheet, or the absorbent body can be made of a corrugated web which is corrugated from a sheet material which, in the process of being corrugated, is drawn in, and optionally elongated in a direction transverse to the corrugations, alternatively drawn-in along a direction transverse to a length of the web. The corrugated web can comprise corrugations of differing heights (H1).

Abstract: An absorbent article for absorbing body liquids, comprising a unitary system of microlayered film constructed and arranged to carry out the multiple functions of liquid intake, liquid uptake and distribution, liquid retention and liquid barrier requisite for such an absorbent article. The unitary system comprises a series of sequentially arranged topside, inside and bottom side regions having different properties needed to perform the functions of the absorbent article.

Abstract: A packaging laminate and method of production are demonstrated by using a single face corrugated cardboard. The single face corrugated cardboard is supplied in rolled form and is processed through a conventional corrugated cardboard shredder to create a flexible resilient packaging material. The method of manufacture is more efficient than conventional manual feeding of standard corrugated cardboard sheets through the shredder. Various embodiments of the invention can be manufactured by adhesively bonding two or more packaging laminates and by the addition of a support layer.

Abstract: A pliable, ductile plate-shaped roof flashing is disclosed. The roof flashing has a laminate structure comprising a composite layer and a foil sheeting on one or both sides of the composite layer. The composite layer comprises a carrier material and one or more non-structural constituents. At least one of the non-structural constituents comprises a heavy metal compound having a density higher that 3.5 g/ml.

Abstract: Apparatus for manufacturing multi-layer metal feedstock material for stamping shaped parts eliminates the need for rolls of metal at the stamping site. Multilayer metal feedstock material is assembled from multiple rolls of metal stock, then folded in a zig zag fashion, or “Z-fold” configuration, whereby the multilayer metal assembly is stacked vertically, usually on conventional pallets, for ease of moving with a forklift or otherwise. The multilayer metal z-fold stack of material is then transported to a parts stamping operation where the material is used as it unfolds as a continuous feed to machines to produce shaped multilayer metal parts. This invention is most useful in making multilayer metal foil z-fold feedstock material and using the z-fold material as continuous feed to processes for making shaped multilayer metal foil parts. The layers may have non-metal layers of material, such as fiber, between the metal layers or on the outside of the metal layers.

Abstract: To provide practical corrugated cardboard pallets that cope with rain, humidity or the like and water-resistant corrugated cardboard for use as the material thereof. Water-resistant paper is used for base paper for corrugated paperboard and base paper for flat paperboard, and cornstarch glue containing 7 to 10 percent by weight modified ketone resin is used as an additive for water-resistance, all of which are used to manufacture the corrugated cardboard. Such corrugated cardboard is used at least in the beam portion to produce a pallet.

Abstract: The method and the device for manufacturing an acoustically effective foil stack (9) made of embossed foil webs (5e, 5f, 5g, 5h) is characterised by the fact that at least two foil webs lying over one another (5a, 5b, 5c, 5d) are embossed at the same time, are conveyed along different length conveying routes (W, W1, W2, W3), and then are brought together into a stack (9), and embossed foil webs (5e, 5f, 5g, 5h) arranged to be lying next to one another are laid down in an offset fashion due to the different length conveying routes (W, W1, W2, W3). A particularly advantageous design of the embossing rollers (1a, 1b) provides foil webs which have knobs with a draped or folded type structure.

Abstract: The present invention discloses a seating system that includes a seat back (20) with one or more plastic panels (22) that extend across a lateral distance of the seat back (20). The seat back (20) preferably includes one or more reinforcements (30) attached to the plastic panels (22).

Abstract: A structured packing element comprises a plurality of corrugated sheets and one planar member positioned adjacent to each of the corrugated sheets. The planar member has a top edge and a bottom edge that are at least proximally aligned with the top and bottom edges respectively of the corrugated sheets. The planar member is further characterized by a middle portion having an open area percent that is higher than the open area percents of the top and bottom portions of the planar member. The structured packing element can be used to form structured packings for distillation applications.

Abstract: A multi-microlayer thermoplastic film structure and methods of making the same. More specifically, this invention relates to a multi-microlayer film having a plurality of corrugated polymer layers and a plurality of thermoplastic elastomer layers. Filler materials and surfactants may be included in either the corrugated polymer layer or the thermoplastic elastomer layer. The multi-microlayer films may be formed in a co-extrusion process.

Abstract: A structured packing with improved packing elements and method of using the structured packing. Each structured packing element comprises corrugated sheets and planar members alternating with and located between the corrugated sheets The planar members are positioned so that at least the lowermost horizontal edges of the planar members and the corrugated sheets are situated proximal to one another. Perforations provided in the planar members and the corrugated sheets are designed to avoid turbulent flows and bulk fluid flow across the packing element while allowing transverse pressure equalization. Different configurations of corrugated sheets may be used with the planar members to form the structured packing.

Abstract: A composite reinforced plastic lumber article, having a generally rectangular cross-section, is formed by extruding a wood particle/polymer composition through an extrusion die which forms a corrugated or relatively thin sheet cross-section core part. The core part is compressed to push corrugations closer together and then cooled in a two-stage cooling process with water spray and submersion followed by vacuum and air blast drying of the article, followed by extruding an outer coating of the same composition over the core part. A continuous plank-like composite article is thus formed and is cooled after the outer coating is extruded over the core part. Opposed surfaces of the article may be embossed to provide a woodgrain appearance. The two-stage article forming process provides rapid cooling of the material to enhance the speed of production of reinforced plastic lumber articles.

Abstract: To provide practical corrugated cardboard pallets that cope with rain, humidity or the like and water-resistant corrugated cardboard for use as the material thereof. Water-resistant paper is used for base paper for corrugated paperboard and base paper for flat paperboard, and cornstarch glue containing 7 to 10 percent by weight modified ketone resin is used as an additive for water-resistance, all of which are used to manufacture the corrugated cardboard. Such corrugated cardboard is used at least in the beam portion to produce a pallet.

Abstract: A method utilized in rolling up materials. In particular, the invention relates to method of rolling corrugated sheets of material. More particularly, the invention relates to a method of rolling pre-formed corrugated sheets of thermoplastic based material. The present invention relates to a method of rolling sheets of thermoplastic material that comprises providing a pre-formed sheet of thermoplastic material, forming a plurality of corrugations on said pre-formed sheet of thermoplastic material; wherein the corrugated shape is made up of inwardly and outwardly extending undulations, rolling the corrugated sheet of thermoplastic material from a first end to a second end; wherein the undulations of a first layer are nestable with the undulations of each subsequent layer of the pre-formed corrugated sheet thermoplastic material.

Abstract: There is disclosed an absorbent article including an absorbent layer and a liquid-permeable surface sheet placed on a liquid-receiving side of the absorbent layer for introducing excreted liquid from the human body to the absorbent layer. The surface sheet is of a corrugated configuration to have valleys and peaks extending in a longitudinal direction of the article and alternately arranged in a transverse direction perpendicular to the longitudinal direction. Each valley has a connecting part raised to connect between two adjacent peaks.

Abstract: A structured packing with improved packing elements and method of using the structured packing. Each structured packing element comprises corrugated sheets and planar members alternating with and located between the corrugated sheets The planar members are positioned so that at least the lowermost horizontal edges of the planar members and the corrugated sheets are situated proximal to one another. Perforations provided in the planar members and the corrugated sheets are designed to avoid turbulent flows and bulk fluid flow across the packing element while allowing transverse pressure equalization. Different configurations of corrugated sheets may be used with the planar members to form the structured packing.

Abstract: A foam pad comprising a surface to which a trim cover can be secured, the surface comprising a channel having a width of up to about 15 mm. Disposed in the channel is one of a male portion or a female portion of a releasably engageable male-female trim cover attachment system. A trim cover having the other of the male or female portion attached thereto may be readily attached to the foam pad. A process and a mold for producing the foam pad are also described. The foam pad is particularly useful as a component of a vehicular seat system (e.g., seat bottom, seat back and the like).

Abstract: The invention relates to a rigid composite metal panel comprising at least two metal parallel plates and/or sheets secured to the peaks and troughs of a corrugated aluminium stiffener sheet arranged between the parallel plates and/or sheets, wherein the corrugated aluminium stiffener sheet is an aluminium brazing sheet product made from an aluminium brazing sheet product including a core sheet (1) made of an aluminium alloy having on at least one surface of the core sheet clad, and preferably on both sides, an aluminium clad layer (2), the aluminium clad layer being made of an aluminium alloy comprising silicon in an amount in the range of 2 to 18% by weight, preferably 5 to 14%, and a layer (3) comprising nickel on the outer surface of the aluminium clad layer. The invention further relates to a method of manufacturing thereof.

Abstract: Corrugated cardboard plates are made by laminating and bonding corrugated cardboards 1, each including a corrugated sheet 1a and at least one liner sheet 1b bonded to the corrugated sheet 1a, to provide a corrugated cardboard laminate 5, which is in turn cut along a plurality of cutting lines b lying perpendicular to a direction parallel to ridge lines a of the corrugated sheet 1a to provide a plurality of corrugated blocks 7. The corrugated blocks 7 are then arrayed in a line to provide an elongated flat corrugated plank 9 in which the top face of one of the corrugated blocks 7 is bonded to the bottom face of the next adjoining corrugated block 7. At least one backing sheet 11a or 11b, made of paper, to one of opposite surfaces of the elongated flat corrugated plank 9 and is subsequently cut into a plurality of corrugated cardboard plates 14 of a predetermined size.

Abstract: A method of forming a support structure on a base from a framework uses a tube of a flexible material divided by dividing walls of flexible material into an array of compartments. Each compartment includes at least one wall including a hollow protrusion or recess. In use the framework is located on the base and the compartments are filled with the filler material so that each compartment is adjacent to one or more other compartments filled with the filler material and so that each hollow protrusion fills with the filler material so that each compartment protrudes into or is protruded into by at least one adjacent compartment so as to interlock adjacent compartment. This increases the overall strength of the support structure.

Abstract: A contact body is disclosed, comprising at least two contact sheets having opposing surfaces and a projection extending outward from one surface of each contact sheet, wherein the projection defines a depression on the opposite surface of the contact sheet, a projection of one contact sheet being disposed within a depression of an adjacent contact sheet to form a projection-depression coupling, and the projection-depression coupling being deformed to form a positive lock. A method and apparatus of connecting contact sheets to form a contact body are also disclosed, that provide for deforming projection-depression couplings formed in two or more interlocking sheets to form positive locks by which assemblies of sheets are formed.

Abstract: A method for the production of ribbed board product, such as fiberboard, flakeboard, or waferboard, which resists fracturing during manufacture. The ribbed board product made according to the invention can be used as decking and in packaging and shipping components.

Abstract: A corrugator unit, particularly for sheets or webs of paper, or similar, of the type comprising at least two rolls (1, 2), having a toothed or corrugated surface (101, 202), and being mutually engaged and pushed against each other by a predetermined pressure or force. The invention provides that the mutual compression between rolls (1, 2) is exerted (4, 5, 106, 21, 22, 25, 26) over the whole axial length of the rolls (1, 2). This may be obtained through mechanical (6) or magnetic (21, 22, 23, 25, 26) means.

Abstract: The present invention provides a structured packing comprising a plurality of corrugated sheets and a plurality of flat, planar members alternating with and located between the sheets to inhibit turbulence in vapor ascending through the structured packing. The plurality of planar members are positioned so that at least the lowermost horizontal edge of the planar members and the corrugated sheets are situated proximal to one another as viewed when said structured packing is in use. When the planar members have substantially the same length and width as the corrugated sheets, the planar members and the corrugated sheets have perforations sized to inhibit transverse liquid and vapor flow while but allowing transverse pressure equalization through the structured packing. The size and number of perforations can be optimized for air separation applications.

Abstract: A structured packing element comprises a plurality of corrugated sheets and one planar member positioned adjacent to each of the corrugated sheets. The planar member has a top edge and a bottom edge that are at least proximally aligned with the top and bottom edges respectively of the corrugated sheets. The planar member is further characterized by a middle portion having an open area percent that is higher than the open area percents of the top and bottom portions of the planar member. The structured packing element can be used to form structured packings for distillation applications.

Abstract: A paper web of the present invention has a longitudinal centerline and a transverse centerline, and comprises a plurality of first regions and a plurality of second regions. The first regions form boundaries separating the second regions, the first regions being substantially in a plane of the paper web. The second regions comprise a plurality of raised out-of-said-plane rib-like elements, the rib-like elements of each second region being disposed parallel to a major rib axis and perpendicular to a minor rib axis. All or most of each first regions have both major rib axis and minor rib axis components. The first and second regions undergo geometric deformation when the web material is subjected to an applied elongation along at least one axis.

Abstract: Corrugated cardboard plates are made by laminating and bonding corrugated cardboards 1, each including a corrugated sheet 1a and at least one liner sheet 1b bonded to the corrugated sheet 1a, to provide a corrugated cardboard laminate 5, which is in turn cut along a plurality of cutting lines b lying perpendicular to a direction parallel to ridge lines a of the corrugated sheet 1a to provide a plurality of corrugated blocks 7. The corrugated blocks 7 are then arrayed in a line to provide an elongated flat corrugated plank 9 in which the top face of one of the corrugated blocks 7 is bonded to the bottom face of the next adjoining corrugated block 7. At least one backing sheet 11a or 11b, made of paper, to one of opposite surfaces of the elongated flat corrugated plank 9 and is subsequently cut into a plurality of corrugated cardboard plates 14 of a predetermined size.

Abstract: The invention is directed to a bond-compatible composite membrane that includes a bituminous material layer and a polyester layer and its use as an intermediate layer between a building structure and exterior finishing materials. Unlike conventional composite membranes, the bond-compatible composite membrane has a rough surface that allows bonding materials to adhere to it. Therefore, mechanical devices are not needed to attach the exterior finishing materials to the building structure.

Abstract: The present invention discloses folded corrugated material for producing segments or strips for use as Easter grass, packing material and the like or for use as flower pot covers, floral wrappings and ribbon materials.

Abstract: The present invention provides a structured packing comprising a plurality of corrugated sheets and a plurality of flat, planar members alternating with and located between the sheets to inhibit turbulence in vapor ascending through the structured packing. The plurality of planar members are positioned so that at least lowermost transverse edges of the planar members and the corrugated sheets are situated at least proximal to one another as viewed when said structured packing is in use. Each of the planar members and the corrugated sheets has perforations sized to inhibit liquid and vapor flows but to allow pressure equalization. The planar members can be strip-like and positions at or near the top and bottom transverse edges of the corrugated sheets or can have the same length and width of the corrugated sheets. The size and number of perforations can be optimized for air separation applications.

Abstract: A deformable sheet material at least partly comprising a sheet metal or metal foil which is corrugated, e.g. by rolling, in continuous waveform in two directions (A, B) substantially orthogonal to each other. The sheet material can comprise aluminum foil with a thickness between 0.005-0.4 mm designed as a ribbon or a strip which prior to the rolling is folded in the longitudinal direction where an intermediate layer, e.g. of aluminum, can be placed between the two material layers.

Abstract: This corrugated strip comprises on its lower edge, in front view, at least one downwardly projecting motif (9) whose contour is such that, if &agr;m and &agr;M designate the ends of the algebraic value of the angle that the tangent to the contour forms with the horizontal direction, then −&agr;m>&agr;0 and &agr;M>&agr;0, wherein &agr;0 designates a predetermined angle at least equal to 5°. The corrugated is particularly useful in air distillation columns on board floating oil platforms or barges.

Abstract: A die-cut sheet having score lines and cutouts which in the form of a sheet of multilayered paperboard including at least two paper layers on the outer and inner sides that are made of different materials, that use a starch-based adhesive, preferably a cornstarch-based adhesive and that each have a basis weight of at least 150 g/m2 is shaped into a box. The die-cut sheet is preferably in the form of a sheet of double-faced or double-wall corrugated board including 30 to 55 flutes/30 cm at a height of 2.3 to 5 mm and a takeup ratio of 1.30 to 1.65, with the liner and the medium having basis weights of 150 to 350 g/m2 and 120 to 200 g/m2, respectively. The box can be used as a paper container for photo-sensitive materials.

Abstract: This invention relates to a connected hollow structure and a packaging member suitable for use as a cushioning material, a protection frame material, a core material of a hollow panel and a carrier for carrying adsorbents. A connected hollow structure comprises a large number of hollow structures 10 having an arbitrary sectional shape and connected in parallel to each other. The connected hollow structure is formed from a piece of sheet and takes the shape resembling a unicursal figure in section. It is possible to form a connected hollow structure which shows elasticity and withstanding strength fit for the purpose and also has a smaller apparent specific gravity by properly selecting the quality of a sheet a, and the sectional shape and size of the hollow structures 10.

Abstract: A paper toweling which provides a combination of strength, bulk and absorbency while presenting an attractive appearance. Included are a single ply paper towel having areas of light and heavy embossing perforations which form diamond shaped islands of heavy embossing perforations surrounded by intersecting bands of light bosses.

Abstract: A built-in packing for the material exchange and/or heat exchange between gases and liquids is composed of a plurality of undulating lattice-like elements arranged next to each other and each mounting element has channels formed by the undulations extending at an angle relative to the vertical direction and extending parallel to each other, wherein the channels of always two adjacent mounting elements intersect each other. Continuous longitudinal struts are provided at the bottom of the channels, wherein the longitudinal struts have contact plates at the ends thereof, and wherein the contact plates are components of an upper and a lower horizontal closed edge strip. The longitudinal struts are connected through transverse struts in a framework-like manner, wherein the transverse struts extend in horizontal planes which extend parallel to the two edge strips.

Abstract: A container having walls made of a paper/plastic laminate having a cardboard core sandwiched between inner and outer face liners, wherein at least one of the face liners is comprised of a face liner laminate. The face liner laminate is composed of an exterior ply of oriented synthetic plastic film whose opposing surfaces are rendered wettable by corona-discharge treatment, and a base paper ply is cold-laminated to the film ply and adhered to the core of the board. The cardboard core may be a fluted medium of corrugated paper board, or it may be a planar stiff paper core. The invention is also directed to a structural member for use in making inexpensive furniture comprising a supporting member and a cardboard core laminated to a face liner laminate. The film ply of the laminate enhances the strength of the container or structural member and imparts water resistance thereto. Because the exposed surface of the film ply is printable, it may have decorative graphics or other printed matter applied thereto.

Abstract: A flexible protective article for engaging a surface of a product for protecting the product from shock during shipment comprising a member formed of a sheet of material of molded pulp having a substantially uniform thickness throughout. The member has a plurality of generally parallel spaced apart flutes formed therein of a substantially uniform thickness extending at an angle between 15.degree. and 75.degree. with respect to a first imaginary plane extending through the flutes and extending inwardly and outwardly with respect to the first imaginary plane. Each of the flutes in a normal unloaded position has first and second legs angled with respect to each other and terminating in an apex. The first leg has a first length and the second leg has a second length. The second length is less in length than the first length. The first and second legs extend at angles on the same side of a second imaginary plane extending perpendicular to the first imaginary plane and extending through the apex.

Abstract: The present invention is directed to a unique thermal insulation panel. More specifically, the present invention is directed to a vacuum insulated panel formed of a highly impermeable evacuated envelope that is supported by a thermal barrier made of a macro-structural support structure having a cell or void size of 0.5 micron or greater. Preferably, the panel includes a getter material. Further, the present invention is directed to a thermal insulation barrier of a macro-structural structure. Preferably, the barrier is formed of elements having a geometric shape of a repetitive three dimensional design that permits stacking of one thermal insulation element with another thermal insulation element having a complimentary geometric shape, and which locks movement of adjacent thermal insulation elements in at least one of the directions 90.degree. to the stacking direction.

Abstract: The present invention relates to a self-sealing flexible plastic valve for a non-latex balloon, to a balloon incorporating such a valve, to a method of manufacturing such a valve, and to a method of manufacturing a balloon incorporating such a valve. The valve is made from two flexible plastic strips, bonded together along the side edges to define a valve passageway or tube, and having an open inlet end and an open outlet end. The inlet end of one or both valve strips flares or otherwise curls outwardly to facilitate opening of the valve to insert a gas supply mechanism to inflate the balloon.

Abstract: A composite slab made of plastic, especially polypropylene, for construction purposes and packing purposes for example is described, said slab according to a preferred embodiment comprising a plurality of layers, each of which consists of a composite that is extruded in a plurality of layers and of which two plane layers and the others are profiled, namely layers that have a corrugated profile with peak lines that are located in a plane, with these layers being welded together along the peak lines on one side of the profiled layer and/or at the intersections of the peak lines of adjacent profiled layers. Layers consisting of a plane slab can be provided between the profiled layers. The composite extruded in several layers comprises two outer layers and a middle layer made of polymers from the same material group, whose middle layer consists of a highly crystalline polymer with incorporated stretch-resistant fibers, whose melting point is at least 15.degree. C.

Abstract: A composite filter media includes a fibrous filtration layer of randomly oriented fibers and one or more pleatable stiffening layers which enable the composite filter media to be pleated and hold or retain its pleats. The pleatable stiffening layer(s) may enhance the dirt holding capacity of the composite filter media especially when positioned upstream of the fibrous filtration layer. The composite filter media may also include a flexible covering layer which functions to block the loss of fibers from the fibrous filtration layer. Preferably, the mean fiber diameter of the fibers in fibrous filtration layer increases and the density of the fibrous filtration layer decreases throughout the thickness of the fibrous filtration layer from one major surface to the other major surface of the fibrous filtration layer.