AU622171B2

AU622171B2 - Sheet material for forming the loop portion for hook and loop fasteners

Info

Publication number: AU622171B2
Application number: AU33783/89A
Authority: AU
Inventors: Dennis L. Becker; Michael Reed Gorman
Original assignee: Minnesota Mining and Manufacturing Co
Current assignee: 3M Co
Priority date: 1988-05-13
Filing date: 1989-04-27
Publication date: 1992-04-02
Anticipated expiration: 2009-04-27
Also published as: KR960013457B1; MX173200B; IL90159A0; IL90159A; ZA893577B; JP2896159B2; CA1333952C; DE68908468D1; DE68908468T2; JPH0218036A; EP0341993B1; KR890016937A; AU3378389A; BR8902225A; EP0341993A1; ES2043010T3

Description

SS 7 F Re 94097 FORM COMMONWEALTH OF AUSTRALIA PATENTS ACT 1952 COMPLETE SPECIFICATION

(ORIGINAL)

FOR OFFICE USE: Class Int Class Complete Specification Lodged: Accepted: Published: Priority: Related Art: Name and Address of Applicant: Minnesota Mining and Manufacturing Company 3M Center Saint Paul Minnesota 55144-1000 UNITED STATES OF AMERICA Address for Service: Spruson Ferguson, Patent Attorneys Level 33 St Martins Tower, 31 Market Street Sydney, New South Wales, 2000, Australia Complete Specification for the invention enti;led: Sheet Material for Forming the Loop Portion for Hook and Loop Fastener? The following statement is a full description of this invention, including the best method of performing it known to me/us 5845/4 1; §l -lw ~a Iv

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SHEET MATERIAL FOR FORMING THE LOOP PORTION FOR HOOK AND LOOP FASTENERS Technical Field The present invention relates to sheet materials adapted to be cut into pieces to form the loop portions for fasteners of the type including releasably engageable hook and loop portions, and methods for making such sheet materials.

Background of the Inventi6n Many sheet materials are known that are adapted to be cut into pieces to form the loop portions fo. fasteners of the type comprising releasably engageable hook and loop portions. Such sheet materials typically comprise a backing and a multiplicity of loops anchored in the backing and 0 0o0 projecting a front surface of the backing so that they may 0 o be releasably engaged with the hooks on the hook portion of °o such a fastener, and can be made by many methods including S°oe 20 conventional weaving, or knitting techniques. Such a sheet material in which the loops are stitched into the backing is co 0o described both in U.S, Patent No. 4,609,581, and in U. S.

,7 770, C11 S a Patent App~aia~enc No A7--t99. While the loop fastener portions made from many such loop materials work well with 0 oo 25 many different hook fastener portions, many of the processes 00 0 by which they are made are more expensive than may be desired, particularly when the loop fastener portions are .o00 intended for a limited amount of use, such as to attach a P. disposable diaper to an infant, or to attach an abrasive disk to a backing pad by which it is driven.

"o Disclosure of Invention 4 0 0; The present invention provides a sheet material adapted to be cut into pieces to form the loop portions for fasteners of the type comprising releasably engageable hook and loop portions, which sheet material provides effective loop fastener portions for such fasteners while being very o i -2inexpensive to manufacture so that they are economical to use when the loop fastener portions are intended for a limited amount of use, such as to releasably attach a disposable diaper or other garment, or to attach an abrasive disk to a backing pad by which it is driven.

According to the present invention there is provided a sheet material adapted to be cut into pieces to form loop portions for fasteners, which sheet material comprises a backing, and a multiplicity of fibers having portions bonded to the backing along a front surface at spaced bonding locations to form arcuate portions of the fibers projecting from the front surface of the backing between the bonding locations. The arcuate portions have a height from the backing of less than about 0.64 centimeters (0.250 inch) and preferably less than about 0.318 centimeters (0.125 inch). The width of the bonding 0 O, locations should be between about 0.005 and 0.075 inch, and the width of the arcuate portions of the fibers shouli be between about 0.06 and 0.35 inch. The fibers in the arcuate 20 portions project to about the same height above the front surface, which height is at least one third, and preferably Sone half to one and one half the distance between the bonding locations, the individual fibers are less than denier in size, and the fibers collectively have a basis 0o0o 25 weight in the range of 5 to 200 grams per square meter (and S. 6 preferably in the range of 10 to 75 grams per square meter) measured along the front surface of the backing to provide sufficient open area between the fibers along the arcuate portions between about 10 to 70 percent open area) to afford ready engagement of the fibers along the arcuate Sportions by the hook portion of the fastener.

oo Preferably the sheet material according to the *0 present invention is made from the fibers and backing by forming the fibers into a sheet of fibers having arcuate portions projecting in the same direction from spaced anchor portions of the sheet of fibers, and bonding the spaced anchor portions of the sheet of fibers to the backing so 4 Ui -3that the arcuate portions project from the front surface of the backing. This forming of the fibers is preferably done by providing first and second generally cylindrical corrugating members each including a plurality of uniformly spaced ridges defining its periphery, mounting the corrugating members in axially parallel relationship with portions of the ridges of the corrugating members in mesh with each other, rotating at least one of the corrugating members, feeding the sheet of fibers between the meshed portions of the ridges of the rotating corrugating members to generally conform the sheet of fibers to the periphery of the first corrugating member, thereby forming the arcuate portions of the sheet of fibers in spaces between the ridges of the first corrugating member and the anchor portions of the sheet of fibers along outer surfaces of the ridges of the first corrugating member, and retaining the formed sheet ,1:1 of fibers along the periphery of the first corrugating member after it has moved past the meshing portions of the ridges. The anchor portions of the sheet of fibers are then G'G 20 bonded to the front surface of the backing while they are on j ,Ao the end surfaces of the ridges on the first corrugating 44 0member, and the thus formed sheet material is separated from a d the first corrugating member.

The ridges can be elongate and generally parallel 25 so that the bonding locations are also elongate and SA generally parallel and are continuous in one direction across the front surface of the backing so that continuous rows of the arcuate portions extend across the backing of GA Gthe sheet material; or alternately the ridges can be elongate, generally parallel, and in a regular pattern of discontinuous lengths so that the parallel bonding locations are also in a regular pattern of discontinuous lengths to to S00 form a regular pattern of discontinuous rows of the arcuate portions along the front surface of the backing. Also it is contemplated that the ridges of the first corrugating member can form interlocking closed patterns circular, diamond shaped, octagonal, etc.) to form corresponding i: 1 -4patterns for the arcuate portions of the fibers along the front surface of the backing, in which case the second corrugating member will be formed with post like ridges to press the fibers into the centers of the closed patterns.

Elongate ridges on the corrugating members can be oriented at any angle in the range of 0 to 90 degrees with respect to their axes so that the rows of arcuate portions, whether continuous or discontinuous, can be oriented along or transverse to the sheet of fibers fed between the corrugating member or at any angle therebetween.

The backing could be a woven, knitted, random woven, nonwoven or other layer of intertwined fibers, but preferably is a continuous polymeric film in the range of about 0.0025 to 0.013 centimeters (0.001 to 0.005 inch) thick which is generally less expensive than a backing of entwined fibers and allows the backing to be printed by conventional methods along one of its surfaces with graphics (such as advertising, instructions or locating marks) which will be visible through the loop portions of the fibers due S 20 to their large percentage of open area. The film may be a :o o single layer of a polymeric material such as polypropylene, polyester, or polyamide; or may have a plurality of layers such as a central layer of a relatively high strength material such as polyester, a layer defining the first 25 surface of a material more easily bonded to the fiber such a 0 as ethylene vinyl acetate or polyethylene, and a layer °0 defining its second surface adapted to adhere the backing to a substrate such as polyethylene or a bonding layer of room-temperature non-tacky thermoplastic material adapted to adhere a fastener portion to a polyolefin layer (such as may be found on a disposable diaper) that can be bonded to the polyolefin layer under heat and pressure that leaves the oo00 polyolefin layer substantially undeformed and will hold the fastener portion to the polyolefin layer with greater force than that which is required to separate an engaged fastener, which bonding layer of room-temperature non-tacky thermoplastic material is described in U.S. Patent application No. 126,746 filed November 30, 1987, and can include from about 40% to about 100% of a thermoplastic material having a softening point of generally below 120 degrees Centigrade and preferably below 100 degrees Centigrade, and from about 60% to about 0% of a tackifying resin that has a softening point below about 105 degrees Centigrade and preferably below 95 degrees Centigrade.

Suitable thermoplastic materials include ethylene and propylene based copolymers such as ethylene/vinyl acetate copolymers, ethylene/acrylic acid copolymers, and ethylene/methacrylic acid copolymers. Preferred thermoplastic materials include ethylene/vinyl acetate copolymers, especially those with a melt flow index from about 40 to about 2500, and preferably with a melt flow index between about 50 and about 1000. Such materials are available commercially as Elvax 40W, Elvax 150, Elvax 210W, Elvax 220W, Elvax 310, Elvax 410, and Elvax 4980W from E. I.

a DuPont de Nemours and Co. of Wilmington, Delaware; Escorene UL7710 and Escorene UL7720 from Exxon Chemical Co., Houston, Texas; and Ultrathene 639-35 and Ultrathene 649-04, available from USI Chemical Co. of Cincinnati, Ohio.

Suitable tackifying resins are preferably solid or semisolid, however liquid tackifying resins can also be used. The tackifying resin, when used, should bc compatible with the thermoplastic material and may include rosin esters, rosin acids, and derivatives of these; hydrogenated rosin esters and rosin acids and derivatives of these; aliphatic hydrocarbon resins; mixed aliphatic/aromatic hydrocarbon resins, polyterpene resins; resins made from the polymerization and hydrogenation of a dicyclopentadiene feed stream; polyterpene resins and aromatic-modified polyterpene resins; resins made from the polymerization and hydrogenation of a C9 hydrocarbon stream; and resins made from the polymerization and hydrogenation of a mixture of alphamethyl styrene, styrene, and vinyl toluene. Preferred tackifying resins include aliphatic hydrocarbon resins such as Escorez 1580 and Escorez 1310, available from Exxon 4 i t -6- Chemical of Houston, Texas; Hercotac 95, available from Hercules Chemical Co. of Wilmington, Delaware; and Wingtack Plus and Wingtack 95, available from the Goodyear Tire and Rubber Company of Akron, Ohio. Additional preferred solid tackifying resins include the aromatic-modified poly'.erpene resins such as Wingtack 86, available from Goodyear; Zonatac 105, available from Arizona Chemical Co. of Panama City, Florida; and Res D-2083, available from Hercules; resins made from the polymerization and hydrogenation of a dicyclopentadiene feed stream such as Escorez 5380, available from Exxon; resins made from the polymerization and hydrogenation of a C9 hydrocarbon stream such as Arkon available from Arakawa Chemical Co. USA of Chicago, Illinois; and resins made from the polymerization and hydrogenation of mixtures of alphamethyl styrene, styrene, and vinyl toluene such as Regalrez 1065, Regalrez 1078, and Regalrez 1094, available from Hercules. Conventional additives for hot-melt adhesives may also be incorporated into the bonding layer, including, but not limited to, I 20 waxes, fillers, oils, pigments, antioxidants, ultraviolet light stabilizers, and heat stabilizers.

The individual fibers may be of many polymeric materials such as polypropylene, polyethylene, polyester, or polyamide, or combinations of such materials such as a core j 25 of polyester and a sheath of polypropylene which provides relatively high strength due to its core material and is easily bonded due to its sheath material. Fibers of one material or fibers of different materials or material combinations may be used in the same sheet material.

The sheet of fibers may be fed between the meshed ridges of the corrugating members in the form of a non woven or random woven sheet or web in which the fibers may or may not be bonded together. In such a sheet the fibers may be disposed in various directions with respect to the direction the sheet of fibers is fed between the corrugating members so that in the resultant sheet material the fibers are dispose& in various directions with respect to the spaced '4 -7bonding locations. In such a sheet to be I I between corrugating members with spaced parallel ridges, preferably a majority of the fibers over 90 percent) project in one direction along the web and the web is fed between the corrugating members with that direction at about a right angles to the ridges on the corrugating members so that in the resultant sheet material a majority of the fibers project generally at about right angles to the parallel bonding locations.

Alternatively, the fibers may be provided in the form of yarns in the range of 50 to 300 denier, the yarns distributed to provide a sheet of generally uniformly distributed fibers by passing them through a comb, and the sheet of fibers fed between corrugating members having elongate parallel ridges oriented in the range of 0 to degrees with respect to their axes in a direction perpendicular to their axes, which results in a sheet material in which the fibers all extend in directions at about the same angles with respect to the parallel bonding locations.

When the contacting portions of the backing and the fibers are of the same thermoplastic material, bonding of the fibers to the backing can be done by sonic welding or other means of applying heat and pressure to fuse the fibers to the backing at the bonding location. Alternatively, or when the contacting portions of the backing and the fibers are of different materials, the fibers may be adhesively bonded to the backing such as by softening a thermoplastic adhesive layer of the backing by sonic energy or other means of applying heat and pressure to adhere the fibers to the backing at the bonding locations.

aoc d Brief Description of Drawing The present invention will be further described with reference to the accompanying drawing wherein like reference numerals refer to like parts in the several views, and wherein: I -8- Figure 1 is a perspective view of a sheet material according to the present invention; Figure 2 is a much enlarged top plan view of the sheet material of Figure 1; Figure 3 is a much enlarged end view of the sheet material of Figure 1; Figure 4 is a schematic view illustrating an apparatus and a method according to the present invention for making the sheet material of Figure 1; Figures 5 and 6 are top and side views respectively illustrating a first alternate embodiment of the apparatus of Figure 4; Figures 7 and 8 are top and side views respectively illustrating a second alternate embodiment of the apparatus of Figure 4; and Figures 9 and 10 are top and side views respectively of an alternate embodiment of a sheet material according to the present invention made by the apparatus of Figures 7 and 8.

S 0 Detailed Description Figres Referring now to the drawing, there is shown in Figures i, 2 and 3 a sheet material according to the present invention, generally designated by the reference numeral 25 which sheet material 10 is adapted to be cut into pieces to form the loop portions for fasteners of the type having releasably engageable hook and loop portions.

Generally the sheet material 10 comprises a transparent thermoplastic film backing 12 of polypropylene or polyester) in the range of about 0.0025 to 0.013 centimeters (0.001 to 0.005 inch) thick having front and rear major surfaces 13 and 14, and a multiplicity of fibers 16 having portions bonded by being fused or adhesively attached) to the front surface 13 of the backing 12 at spaced elongate generally parallel bonding locations 18 that are continuous in one direction along the front i -9surface 13 to form arcuate portions 20 of the fibers 16 projecting from the front surface 13 of the backing 12 between the bonding locations 18 in continuous rows transversely across the sheet material 10. The arcuate S portions 20 of the fibers 16 have a generally uniform height from the backing 12 of less than about 0.64 centimeters (0.250 inch) and preferably less than about 0.318 centimeters (0.125 inch), the height of the fibers 16 is at least one third, and preferably one half to one and one half times the distance between the bonding locations 18, the individual fibers 16 are less than 15 denier (preferably in the range of 1 to 10 denier) in size, nd the fibers 16 without the backing 12 have a basis weight in the range of to 200 grams per square meter (and preferably in the range of 10 to 75 grams per square meter) measured along the first surface 13 to provide sufficient open area between the fibers 16 along the arcuate portions 20 between about and 70 percent open area) to afford ready engagement of the fibers 16 along the arcuate portions 20 by the hook portion of the fastener.

The fibers 16 can be disposed in various directions with respect to the parallel bonding locations 18 and may or may not be bonded together at crossover points in the arcuate portions 20; can be disposed in various directions with respect to the parallel bonding locations 18 with the majority of the fibers 16 over 90 percent) extending in directions at about a right angle to the bonding locations 18; or all of the fibers 16 can extend in directions generally at right angles to the spaced generally parallel bonding locations 18.

The backing 12 may have printing 22 along either one or both of its surfaces 13 or 14 applied by conventional printing techniques, which printing 22 is readily visible through the arcuate portions 20 of the fibers 16.

Figure 4 schematically illustrates a method according to the present invention for forming the sheet material 10 which generally comprises forming the fibers 16 i into a sheet of fibers having arcuate portions projecting in the same direction from spaced generally parallel anchor portions 24 of the sheet, and bonding the spaced generally parallel anchor portions 24 of the sheet of fibers 16 to the front surface 13 of the backing 12 with the arcuate portions of the fibers 16 projecting from the front surface 13 of the backing 12. This method is preferably performed by providing first and second heated 280 degrees F) corrugating members or rollers 26 and 27 each having an axis and including a plurality of circumferentially spaced generally axially extending ridges 28 around and defining its periphery, with the ridges 28 having outer surfaces and defining spaces between the ridges 28 adapted to receive portions of the ridges 28 of the other corrugating member in meshing relationship with the sheet of fibers between the meshed ridges 28 and to afford rolling engagement between the ridges 28 and spaces of the corrugating members in the manner of gear teeth. The corrugating members 26 and 27 are mounted in axially parallel relationship with portions of 2 20 the ridges 28 of the corrugating members 26 and 27 meshing generally in the manner of gear teeth; at least one of the corrugating members 26 or 27 is rotated; and the sheet of fibers is fed between the meshed portions of the ridges 28 of the corrugating members 26 and 27 to generally conform the sheet of fibers to the periphery of the fiLst corrugating member 26 and form the arcuate portions of the o fibers 16 in the spaces between the ridges 28 of the fir-t corrugating member 26 and the generally parallel anchdr portions 24 of the sheet of fibers along the outer surfaces of the ridges 28 on the first corrugating member 26. The formed sheet of fibers is retained along the periphery of the first corrugating member 26 after it has moved past the meshed portions of the ridges 28; the backing 12 is bonded to the parallel anchor portions 24 of the sheet of fibers on the end surfaces of the ridges 28 on the first corrugating member 26 as by the action of a sonic welder 30 or by other sources of heat and pressure such as heat from within the -11first corrugating member 26; and the bonded backing 12 and fibers 16 or sheet material 10 is separated from the first corrugating member 26.

The sheet of fibers fed between the meshed portions of the ridges 28 of the corrugating members 26 and 27 can be in the form of a non woven web or sheet, or, as illustrated in Figure 4, in the form of yarns 33 distributed to provide a sheet of uniformly distributed fibers by passing the yarns 33 through a comb 34 and fed between the meshed portion of the ridges 28 of the corrugating members 26 and 27 with all of the fibers 16 extending generally perpendicular to the axes of the corrugating members 26 and 27. Corrugating members 26 and 27 adapted to have such a sheet of fibers 32 fed into them can have their ridges 28 oriented generally in the range of 0 to 45 degrees with respect to their axes, but preferably have their ridges 28 oriented at about 5 degrees with respect to their axes so o that the sonic welder 30 will always be adjacent and heating oo the parallel portions 24 of the sheet of fibers along a portion of at least one of the ridges 28 to help even out the energy output of the sonic welder 30 and so that the fibers 16 in the sheet material 10 all extend in directions at about right angles 85 degrees) to the parallel bonding locations 18.

Additionally, the method can further include printing the backing along one of its surfaces prior to the 4 bonding step, as along its rear surface 14 with a printer 36, which may preferably be done at a location remote from the corrugating members 26 and 27.

Figures 5 and 6 schematically illustrate a first alternate way to perform the method according to the present invention for forming a sheet material 40 according to the present invention, which method generally comprises forming fibers 38 into a sheet having arcuate portions 41 projecting in the same direction from spaced generally parallel anchor portions of the sheet, and bonding the spaced anchor portions of the sheet of fibers with the fibers along a I~n -12front surface of a backing 43 with the arcuate portions 41 projecting from the front surface of the backing 43. As illustrated, the method can be performed by providing first and second cylindrical heated corrugating members or rollers 44 and 45 each having an axis and including a plurality of generally annular, circumferentially extending, axially spaced ridges 46 around and defining its periphery, with the ridges 46 having outer surfaces and defining spaces between the ridges 46 adapted to receive portions of the ridges 46 of the other corrugating member 44 or 45 in meshing relationship with the sheet of fibers between the meshed portions of the ridges 46. The corrugating members 44 and are mounted in axially parallel relationship to mesh portions of the ridges 46 of the corrugating members 44 an, 45; at least one of the corrugating members 44 or 45 is rotated; and the sheet of fibers is fed between the meshed portions of the ridges 46 of the corrugating members 44 and to generally conform the sheet of fibers to the periphery of the first corrugating member 44 and form the arcuate portions 11 of the fibers in the spaces between the ridges 46 of the first corrugating member 44 and the gene:ally parallel anchor portions of the fibers along the outer 2 surfaces of the ridges 46. The formed sheet of fibers is retained along the periphery of the first corrugating member 44 after separation of the ridges 46; the backing 43 is bonded to the parallel anchor portions 42 of the sheet of fibers on the end surfaces of the ridges 46 of the first corrugating member 44 at spaced elongate generally parallel bonding locations corresponding to the end surfaces of the ridges 46 on the first corrugating member 44 as by the action of a sonic welder 50 or by other sources of heat and 4 pressure such as heat from within the first corrugating member 44; and the thus completed sheet material 40 is separated fr-m the first corrugating member 44.

The fibers 38 fed between the meshed ridges 46 of the corrugating members 44 and 45 can be in the form of a non woven web forme( Dy adhering the fibers together, or

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-13another sheet formed of the fibers that has sufficient internal strength so that the sheet of fibers will corrugate longitudinally to conform to the ridges 46 as it is pulled into the nip between the meshing ridges 46 of the corrugating members 44 and 45. Preferably a majority of the fibers 38 in such a non woven sheet of fibers are oriented transversely of the directionthe sheet of fibers is fed between the corrugating members 44 and 45 so that a majority of the fibers in the resultant sheet material 40 extend in directions at about right angles to the parallel bonding locations. Additionally, the method can further include printing the backing along one of its surfaces prior to the bonding step (not shown).

Like the sheet material 10, the sheet material made by the method illustrated in Figures 5 and 6 comprises the backing 43 (which can be a thermoplastic film), and the fibers 38 which are bonded by being fused or adhesively attached) to the backing 43 at the spaced elongate generally parallel bonding locations along the front surface, which bonding locations are continuous in one direction across the sheet material 40 to form arcuate portions 54 of the fibers 38 projecting from the front surface of the backing 43 between the bonding locations in continuous rows, except that the continuous rows of arcuate S 25 portions 54 in the sheet material 40 extend longitudinally along the sheet material 40 instead of transversely across the sheet material as in the case of the sheet material UFigure 7 and 8 schematically illustrate a second alternate way to perform the method according to the present invention for forming a sheet material 60 illustrated in SFigures 9 and 10, which method illustrated in Figures 7 and 8 generally comprises forming fibers 59 into a sheet having arcuate portions 61 projecting in the same direction from spaced generally parallel anchor portions 62 of the sheet of fibers, and bonding the spaced generally parallel anchor portions 62 of the sheet of fibers to a front surface 58 of a backing 63 to form bonding locations 68 vith the arcuate portions 61 projecting from the front surface 58. As

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-14illustrated, the method can be performed by providing first and second cylindrical heated corrugating members or rollers 64 and 65 each having an axis and including a plurality of circumferentially spaced generally axially extending discontinuous ridges 66 around and defining its periphery, with the ridges 66 on each corrugating member 64 or having outer surfaces and defining spaces between the ridges 66 adapted to receive a portion of the ridges 66 of the other corrugating member 64 or 65 in meshing relationship in the manner of a pair of gears with the sheet of fibers 59 between the meshed portions of the ridges 66. The corrugating members 64 and 65 are mounted in axially parallel relationship to mesh portions of the ridges 66 of the corrugating members 64 and 65 in the manner of gear teeth; at least one of the corrugating members 64 or 65 is rotated; and the sheet of fibers 59 is fed between the meshed portions of the ridges 66 of the corrugating members 64 and 65 to generally conform the sheet of fibers to the periphery of the first corrugating member 64 and form the arcuate portions 61 of the fibers in the spaces between the ridges 66 of the first corrugating member 64 and the generally parallel anchor portions 62 of the sheet of fibers along the outer surfaces of the ridges 66. The formed sheet of fibers is retained along the periphery of the first corrugating member 64 after it moves past the meshing portions of the ridges 66; the backing 63 is bonded to the parallel anchor portions 62 of the sheet of fibers on the end surfaces of ridges 66 of the first corrugating member 64 as by the action of a sonic welder 67 or by other sources of heat and pressure such as heat from within the first 4' corrugating member 64; and the thus completed sheet material 60 is separated from the first corrugating member 64.

The fibers 59 can be fed between the meshed portions of the ridges 66 of the corrugating members 64 and 65 in the form of yarns 70 distributed to provide a sheet of uniformly distributed fibers 59 by passing the yarns through a comb 72 and fed between the meshed ridges 66 of -i t 6 I, *;IIT i 4 Is Sthe corrugating members 64 and 65 with all of the fibers extending generally perpendicular to the axes of the corrugating members 64 and 65, in which case the corrugating members 64 and 65 can have their ridges 66 oriented in the range of 0 to 45 degrees with respect to their axes, but preferably have their ridges 66 oriented at about 5 degrees with respect to their axes so that the sonic welder 67 will always be adjacent and heating the parallel anchor portions 62 of fibers along a portion of one of the ridges 66 to help even out the energy output of the welder 67 and so that in the sheet material 60 the fibers all extend in directions at about right angles 85 degrees) to parallel bonding locations 68 between the fibers 59 and the backing 63.

Alternatively, the fibers 59 fed between the meshed ridges 66 of the corrugating members 64 and 65 can be in the form of a non woven or random woven web formed by adhering fibers together or laying unattached fibers together. In that case the ridges 66 may be oriented at any angle with respect to the axes of the corrugating members 64 and 65, and preferably a majority of the fibers in such a sheet of fibers are oriented at right angles to the ridges 66 so that a majority of the fibers in the resultant sheet material extend in directions at about right angles to the parallel bonding locations 68. Additionally, the method can further include printing the backing along one of its surfaces prior to the bonding step (not shown). Additionally, the method can further include printing the backing along one of its surfaces prior to the bonding step (not shown).

Like the sheet materials 10 and 40, the sheet 30 material 60 made by the method illustrated in Figures 7 and 8 and illustrated in Figures 9 and 10 Comprise the backing 63 (which can be a thermoplastic film), and the fibers 59 which are bonded by being fused or adhesively attached) to the front surface 58 of the backing 63 at the spaced elongate generally parallel bonding locations 68 to form rows of the arcuate portions 61 of the fibers 59 projecting from the front surface 58 of the backing 63 i i -16between the bonding locations 68, except that the rows of arcuate portions 69 are discontinuous and form a regular pattern along the sheet material 60 instead of being continuous in one direction across the sheet material as in the case of the sheet materials 10 and The following are illustrative examples of sheet materials according to the present invention formed by the method described above.

Example 1 A sheet material according to the present invention was made using 2.4 denier individual polypropylene fibers commercially available as style 80/2 yarn, 70/34 denier Solution-dyed Stuffer Crimped Olefin Fibers from Roselon Industries of New York, and a backing of conventional polypropylene film (some of which was printed on one surface) with a thickness of about 50 microns. The yarns of polypropylene filaments were passed through a comb having 6.3 teeth per centimeter (16 teeth per inch) to form a sheet-of uniformly distributed filaments that wias then fed between two corrugating rollers with meshing ridges of the type described above with reference to Figure 4, carried along the periphery of a first one of the corrugating rollers, and had the parallel anchor portions of the sheet of fibers carried along the outer surfaces of the ridges ultrasonically fused to the backing in the manner described above. The ridges and spaces between the ridges were shaped to cause a feed rate of the sheet of fibers about twice that of the film backing and to result in sheet material having parallel elongate bonding locations generally perpendicular to all of the fibers, having a transverse width of about o 0.076 centimeter and spaced every 0.381 centimeter along the sheet material; and having projecting arcuate portions of the fibers roughly semicircular in shape with heights of about 0.381 centimeter (0.15 inch) between the parallel bonding locations. The printing on the backing could be easily seen through the arcuate portions of the fibers. The I1 -17sheet material was tested for Dynamic Shear and T-Peel in accordance with the test methods described at the end of this specification when engaged with a 2 inch by 1 inch sized piece of both the mushroom headed hook material sold under the trade designation SJ-3492, "SCOTCHMATE" Fastener, by Minnesota Mining and Manufacturing Co., St. Paul, Minn., and a hook material (called "Extruded Hook Material" herein) made in accordance with the teaching in U.S. Patent Application No. 142,551, filed January 11, 1988, by extruding a thermoplastic resin through a die shaped to form a base layer and spaced ridges projecting above an upper surface of the base layer that have the cross sectional shape of the hook portions to be formed, transversely cutting the ridges at spaced locations along their length to form discrete portions of the ridges, and stretching the backing layer to separate those portions of the ridges which are then the spaced hook members, which hook members each comprise a stem portion attached at one end to the backing, and a head portion at the end of the stem portion opposite the backing, the hook members each have a height dimension from the upper surface of the backing of 0.102 centimeter (0.04 inch); the stem and head portions each have generally the same thickness dimension of about 0.025 centimeter (0.01 inch) in a first direction parallel to the surfaces of the backing; the stem portions each have a width dimension of about 0.027 centimeter (0.01 inch) in a second direction generally at a right angle to the first direction and parallel to the surfaces of the backing, and the head portions each have a width dimension in the second direction that is about 0.066 centimeter (0.026 inch) greater than the width dimension of the stem portion and a total width of about 0.066 centimeter (0.026 inch); the fastener portion includes about 70 hook members per square centimete, (450 hook members per square inch); while the total cross sectional area occupied by the head portions in a plane parallel to the upper surface is about 11.7 percent of the area of the upper surface.

I_ -18- The average results obtained are tabulated in table 1 below.

Example 2 A sheet material according to the present invention was made as described in Example 1 except that the individual fibers used were 6.2 denier polypropylene fibers commercially available in the form of 420/68 yarn from Phillips Fibers Incorporated, Greenville, SC. The printing on the backing of the sheet material could be easily seen through tL arcuate portions of the fibers. The sheet material was tested as in Example i, and the average results Uobtained are tabulated in table 1 below.

Example 3 A sheet material according to the present invention was made as described in Example 1 except that the individual fibers used were 6.2 denier polypropylene fibers commercially available as 420/68 yarn from Phillips Fibers Incorporated, Greenville, SC., and the ridges and spaces between the ridges of the corrugating rollers were shaped to cause projecting arcuate portions of the fibers roughly semicircular in shape with heights of about 0.318 centimeter (0.125 inch) between the parallel bonding locations. It was noted that the printing on the backing could be easily seen through the arcuate portions of the fibers. The sheet material was tested as in Example 1, and the average results obtained are tabulated in table 1 below.

Example 4 A sheet material according to the present invention was made as described in Example 1 except that no SZ comb was used and the individual fibers used were 11 denier polypropylene sheath and polyester core fibers commercially available from BASF Corporation, Williamsburg VA, a nonwoven web having a basis weight of approximately 35 grams per square meter was formed from the fibers after orienting the

I

V

-19majority or about 90 percent of the fibers in one direction by standard carding techniques and the nonwoven web was fed into the rollers with said one direction perpendicular to the axes of the rollers, and the ridges and spaces between the ridges of the corrugating rollers were shaped to cause projecting arcuate portions of the fibers roughly semicircular in shape with heights of about 0.318 centimeter (0.125 inch) between the parallel bonding locations. The sheet material was tested as in Example 1, and the average results obtained are tabulated in table 1 below.

TABLE 1 Extruded Hook Material Scothmate Hooks Dynamic Shear T-Peel Dynamic Shear T-Peel (pounds) (pounds) (pounds) (pounds) Example 1 15.0 1.5 9.8 0.6 2 10.9 0.9 9.9 0.4 3 10.9 0.8 7.5 0.3 4 9.8 1.5 6.2 0.6 backings elongated and hooks did not release from loops Comparative Examples 5-19 A series of sheet materials according to the present invention, Examples 5-13, were made as described in Example 4 except that the individual fibers used were a mixture of percent of the 11 denier polypropylene sheath and polyester core fibers commercially available from BASF Corporation, Williamsburg VA, and 35 percent 6 denier polypropylene fibers commercially available from Hercules Inc., Wilmington, Del. The nonwoven webs made from those fibers were varied in their densities to produce a series of basis weights for the fibers (not including the backing) measured along the first surfaces of the backing of the sheet material.

Also, sheet materials according to the present invention, Examples 14-19, were made as described in Example 1 except that the individual fibers used were 2.9 denier polypropylene fibers commercially available in the form of 100/34 yarn from Amoco Fabrics and Fibers Company, Atlanta, GA, the backing of the sheet material was not printed, and the fiber contents of the sheet materials were varied in their densities or basis weights by varrying the nuber of yarns per width to produce a series of basis weights for the fibers (not including the backing) measured along the first surfaces of the backing of the sheet material.

All of the sheet materials thus made were tested for T-Peel in accordance with the test method attached at the end of this specification when engaged with a 2 inch by 1 inch sized piece of both the mushroom headed hook material sold under the trade designation SJ-3492, "SCOTCHMATE" Fastener, by Minnesota Mining and Manufacturing Co., St. Paul, Minn., and the average results obtained are tabulated in table 2 below.

Additionally, the arcuate portions of the fibers on certain of the sheet materials were measured on an IBAS image analyzer using routine #455, with 6 fields 2.2 square centimeters in size being measured for each sheet material, and the average results for percent open area obtained are tabulated in table 2 below.

i L- j i rPy 4 -21-

TABLE

Fiber Basis Wt.

(gms/sq.

meter) Fiber Source Example (see above) T-Peel (Counds) Open Area 6 1C 7 8 9 11 12 13 14 16 17 18 19 Non Woven Non Woven Non Woven Non Woven Non Woven Non Woven Non Woven Non Woven Non Woven Yarn Yarn Yarn Yarn Yarn Yarn Mixture Mixture Mixture Mixture Mixture Mixture Mixture Mixture Mixture 20 35 50 63 77 78 80 85 139 6.5 12 25 50 120 140 64 176 336 314 516 324 240 210 118 168 160 282 284 82 48.5 41.9 9.3 4 4t 4 I 0 0 Example A sheet material according to the present invention was made to demonstrate adhesively bonding fibers to a backing. The sheet material was made as described in Example 1 except that no comb was used; the fibers used were 9 denier polypropylene staple fibers commercially available from SHercules Incorporated, Norcross, GA; the backing used was 0.0056 centimeter (0.0022 inch) polypropylene film extrusion coated with about 0.005 centimeter (0.002 inch) of low melt I c -22temperature tackified ethylene vinyl acetate hot melt adhesive; a nonwoven web having a basis weight of approximately 17 grams per square meter was formed from the fibers by heat fusing them together after orienting the majority or about 90 percent of the fibers in one direction and the nonwoven web was fed into the corrugating rollers with said one direction perpendicular to the axes of the corrugating rollers; the backing was adhesively bonded to the parallel portions of the fibers carried along the outer surfaces of the ridges by heating the first roller to soften the ethylene vinyl acetate coating rather than by sonic welding; and the ridges and spaces between the ridges on the corrugating rollers were shaped to cause projecting arcuate portions of the fibers roughly semicircular in shape with radii of about 0.318 centimeter (0.125 inch) between the parallel bonding locations. The sheet material was not tested, although it appeared to work as well as the better examples described above.

20 Example 21 a, ,A sheet material according to the present i nvention was made generally as described in Example 1 except that the fibers used were those commercially available from Hercules as 10d T-181 fibers. A very open non woven web having a basis weight in the range of about I to 25 grams per square meter was formed from the fibers by randomly orienting the fibers and point bonding about 4 to 6% of the fibers together at their cross over points, and that web was then fed between the two corrugating rollers with meshing ridges of the type described above with reference to Figure 4, carried along the periphery of a a, F ofirst one of the corrugating rollers, and had the parallel a a anchor portions of the web or sheet of fibers carried along the outer surfaces of the ridges ultrasonically fused to the backing in the manner described above.

11 ''t i e 33 783/89 -23- Example 22 A sheet material according to the present invention was made generally as described in Example 1 except that the backing of the sheet material was a bilayered film including a layer of low melt tackified ethyl vinyl acetate with a softening point of 150 degrees Fahrenheit and a layer of polypropylene similar to the film of example one; and that a rubber roll was used in place of the sonic horns to achieve adhesive bonding of the fibers to the layer of ethyl vinyl acetate through the application of heat and pressure.

Example 23 A sheet material according to the present invention was made generally as described in Example 1 except that no comb was used and the multiplicity of fibers used to form the sheet of fibers were those commercially available from Hercules as 9d T-101 fibers. The fibers were used in an amount to provide a basis weight of 45 grams per square meter for the sheet of fibers, and the orientation of the fibers in the sheet was estimated to be in a ratio of about seven in the longitudinal direction to one in the cross direction.

IL

i ii 2 -24- PEEL TEST

EQUIPMENT:

S 1. Tensile Tester Instron Model TM equipped with "CT" load cell or tensile tester (Thwing Albert) Model "Intelect".

2. 11 1/4 lb. (5.0 0.1 kg) roller with a 4 1/8" (104.8 mm) diameter and a 3" (76 mm) length capable of being rolled by hand or mechanically.

3. Hook and loop material in the width supplied, not to exceed 2" (51 mm) width; materials greater than 2" (51 mm) in width should be slit to a 2" (51 mm) width.

4. Scissors

SAMPLE:

A strip of the appropriate hook or mushroom material at Sleast 7" (178 mm) long by width and an equal length of the 0 loop to which it will be mated. If the samples are removed 20 from a roll of material remove the outer lap of material before selecting the required number of strips. On each 0 strip the end closest to the center of the roll must be marked. These markings are used to mark the directionality of the specimens.

INSTRUMENT PREPARATION: 1. See TM App. #3 for load cell calibration procedure using "CT" load cell.

2. See Instron for the following conditions: a. Crosshead speed: 12 in./min. (305 mm/min.) b. Chart speed: 5-12 in./min. (127-305 mm/min.) c. Gauge length: 3 1/8" (76.2 3.2 mm) d. Load range: 10 lbs. (44.5 N) full scale load e. Peel distance: 3" (76.2 mm)

CONDITIONS:

All hook and loop samples should be laid functional side up and conditioned for at least 24 hours at 70 2 0

F

(21.1 1.1 0 C) and 65 2% relative humidity prior to testing specimens.

PROCEDURE:

1. Carefully align and superimpose the hook strip over the loop strip so that the hook strip covers the loop strip, and the marked ends are matched. Join the 1 strips together lightly using finger pressure.

2. Using the roller, engage the entire length of the mated strips by rolling over surface at a rate of approximately 12" (305 mm)/min. making one pass in each direction 3 times. Then hand separate at least 2-1/2" (63.5 mm) but no more than 3" (76.2 mm) of the combined specimens.

3. Place the free ends of the specimen to be tested in the Instron with the hook strip end in the upper clamp and the free end of the loop strip in the lower clamp.

The peel line should be centered.

4. Turn on the pen and chart and start the peel test.

Ignore the first peak and from the remaining peaks, select the five highest peaks and calculate an average for the peel force value.

6. A total of 6 separate specimen combinations will be tested, 3 with marked ends together and 3 with marked ends opposite.

3 each: hook X loop hook

X

I I loop X 7. The average value of the 6 peel tests should be recorded in pounds per inch width to the nearest tenth of a pound. This value characterizes one sample.

J

I_

-26- SHEAR STRENGTH TEST

EQUIPMENT:

1. Tensile Tester Instron Model TM equipped with "CT" load cell or tensile tester, (Thwing Albert) Model "Intelect" 2. 11 1/4 lb. (5.0 0.1 kg) roller with a 4-1/8" (105 mm) diameter and a 3" (76 mm) length capable of being rolled by hand or mechanically.

3. Hook and loop material in the width supplied, not to exceed 2" (51 mm) width. Materials greater greater than 2" (51 mm) in width should be slit to a 2" (51 mm) width.

4. Scissors.

Bell jar with a super saturated solution of magnesium acetate and water in bottom to keep R.H. at 65% at (21 0

C).

SAMPLE:

A strip of the appropriate hook or mushroom material at least 4" (102 mm) long by width and an equal length of the loop to which it will be mated. If the samples are removed from a roll of material remove the outer lap of material before selecting the required number of strips.

INSTRUMENT PREPARATION: 1. Calibrate the load cell.

2. Set the Instron for the following conditions: a. Crosshead speed: 12" (305 mm)/min.

b. Chart speed: 5-12" (127-305 mm)/min.

c. Guage length: 3 1/8" (76 3 mm) d. Load range: 100 lbs. (445 N) full scale load C~cl Iplllllll LIWU1-Lllttl.li -27-

CONDITIONING:

All hook and loop samples should be laid functional side up and conditioned for at least 24 hours at 70 2 0 F (21 1 0 C) and 65 2% relative humidity prior to testing.

PROCEDURE:

i. Place the 4" (102 mm) long strip of loop material, loop side up, on a flat rigid surface. Fasten end of the loop to the surface with pressure sensitive tape to prevent movement.

2. Carefully align and superimpose 2 1/16" (50 2 mm) of the hook strip over the loop strip. Join the strips together lightly using finger pressure.

3. Using the roller, engage the mated strips by rolling over the surface at a rate of approximately 12" per minute (305 mm/min.) making one pass in each direction 3 times.

4. Place the free ends of the specimen to be tested in the instron with the hook strip end in the upper clamp and the free end of the loop strip in the lower clamp.

The shear line should be centered.

Turn on the pen and chart. Then start the shear test.

6. Observe and record the maximum value obtained during the complete separation of each of the specimen combinations.

7. A total of 4 separate specimens will be tested and the average calculated to characterize one sample.

64 d

Claims

1. A method for forming a sheet material adapted to be cut into pieces to form a plurality of loop portions for fasteners, each said fastener being of the type comprising a loop portion and a hook portion releasably engageable with said loop portion, said method comprising: providing a backing having front and rear major surfaces and a plurality of fibers; forming the fibers into a sheet having arcuate fiber portions projecting in the same direction from spaced anchor portions of the sheet of fibers, the arcuate portions having a height from the anchor portions of less than 0.64 centimeters; and thereafter bonding the spaced anchor portions of the sheet of fibers to the front surface of the backing with the arcuate portions of the fibers projecting from the front surface of the backing; the sheet formed by the fibers having a basis weight in the range of 5 to 200 grams per square meter measured along the front surface of the backing to provide sufficient open area between the fibers to afford ready engagement of the hook portion of a said fastener with the fibers in the sheet material.

2. A method for forming a sheet material according to claim 1 wherein said forming step comprises the steps of: providing first and second generally cylindrical corrugating members each having an axis and including a plurality of spaced ridges defining the periphery of the corrugating member, the ridges having outer surfaces and defining spaces between said ridges adapted to receive portions of the ridges of the other corrugating member in meshing relationship with the sheet of fibers therebetween; mounting the corrugating members in axially parallel relationship with portions of the ridges in meshing relationship; rotating at least one of the corrugating members; feeding the sheet of fibers between the meshed portions of the ridges to generally conform the sheet of fibers to the periphery of the first corrugating member and form the arcuate portions of the fibers in the spaces between the ridges of the first corrugating member and the anchor portions of the sheet of fibers along the outer surfaces of the ridges of the first corrugating member; and RLF/1501h -29- retaining the formed sheet of fibers along the periphery of the first corrugating member after movement past the meshing portions of the ridges; wherein said bonding step occurs with the formed sheet of fibers along the periphery of the first corrugating member after movement past the meshing portions of the ridges; and said method further includes separating the sheet material from the first corrugating member.

3. A method according to claim 2 wherein in said feeding step the sheet of fibers fed between the meshed portions of the ridges of the corrugating members is in the form of a non woven web.

4. A method according to claim 2 wherein said ridges are elongate and parallel, and in said feeding step the sheet of fibers fed between the meshed portions of the ridges of the corrugating members is in the form of a non woven web having a plurality of the fibers projecting generally at a right angle to the ridges. A method according to claim 2 wherein said ridges are elongate and parallel and are oriented at an angle in the range of 0 to 45 degrees with respect to the axes of the corrugating members, and said feeding step includes the steps of: providing the fibers in the form of yarns in the range of 50 to 300 denier; distributing the yarns to provide a sheet of generally uniformly distributed fibers; and feeding the sheet of fibers between the meshed ridges of the gear with all of the fibers extending generally at a right angle to the axes of the corrugating members.

6. A method according to claim 2 wherein said ridges are oriented at an angle of about 5 degrees with respect to the axes of the corrugating members, and said feeding step includes the steps of; providing the fibers in the form of yarns in the range of 50 to 300 denier; distributing the yarns to provide a sheet of generally uniformly distributed fibers; and feeding the sheet of fibers between the meshed portions of the ridges with all of the fibers extending generally at a right angle to the axes of the corrugating members. RLF/1501h

7. A method according to claim 1 further including the step of imposing printing on the backing along one of its surfaces prior to said bonding step.

8. A method according to claim 1 wherein the backing and the fibers comprise the same thermoplastic material, and said bonding step comprises fusing the fibers to the backing at the bonding locations.

9. A method according to claim 1 wherein said bonding step comprises adhesively bonding the fibers to the backing at the bonding locations. A sheet material made by the method of claim 1 and adapted to be cut into pieces to form a plurality of loop portions for fasteners, each said fastener being of the type comprising a loop porfionjand a hook portion releasably engageable with said loop portion, said sheet material comprising: S" o a backing having front and rear major surfaces; and o a multiplicity of fibers having portions bonded to said backing along said front surface at spaced bonding locations to form arcuate portions of said fibers projecting from the front surface of said backing between said bonding locations, said arcuate portions having a height from said backing of less than about 0.64 centimeters, and said fibers having a basis weight in the range of 5 to 200 gramc per square meter measured along said first surface to provide sufficient open area between said fibers along said arcuate portions to afford ready engagement of said fibers along said arcuate portions by the hook portion of a said fastener.

11. A sheet material according to claim 10 wherein the fibers in said arcuate portions project to substantially constant height above said front surface, and said height is at least one third the distance between said bonding locations.

12. A sheet material according to claim 10 wherein said bonding locations are elongate, generally parallel, and continuous in one direction along said front surface of said backing to form continuous rows of said arcuate portions along said front surface of said backing.

13. A sheet material according to claim lowherein said bonding locations are elongate, generally parallel, and in a regular pattern of discontinuous lengths to form a pattern of discontinuous rows of said arcuate portions along said front surface of said backing. j V RLF/1501h S II -31-

14. A sheet material according to claim lOwherein said bonding locations are elongate and generally parallel, and said fibers are disposed in various directions with respect to said parallel bonding locations. A sheet material according to claim lowherein said bonding locations are elongate and generally parallel, and said fibers are disposed in various directions with respect to said parallel bonding locations with the majority of said fibers extending in directions generally at right angles to said bonding locations.

16. A sheet material according to claim l0wherein said bonding o° 0 locations are elongate and generally parallel, and essentially all of "said Fibers extend in directions generally at right angles to said spaced 0 "generally parallel bonding locations. 'o 17. A sheet material according to claim lowherein said fibers have a basis weight in the range of 10 to 75 grams per square meter measured S"o" along said front surface of said backing, the fibers in said arcuate portions project to about the same height above said front surface, and said height is in the range of one half to one and one half the distance between said bonding locations.

18. A sheet material according to claim l0wherein said backing is a polymeric film material less than 0.013 centimeters thick.

19. A sheet material according to claim 10wherein said backing is a polymeric film material and has printing along one of said surfaces, said printing being visible through said arcuate portions of said fibers. A sheet material according to claim lOwherein said backing and said fibers comprise the same thermoplastic material, and said fibers are fused to said backing at said bonding locations.

21. A sheet material according to claim l0wherein said backing and said fibers are adhesively bonded to said backing at said bonding locations.

92. A.disposable garment including a fastener comprising a loop portionand a hook portion releasably engageable with said loop portion, said loop portion comprising: a backing having front and rear major surfaces; and a multiplicity of fibers having portions bonded to said backing along said front surface at spaced bonding locations to form arcuate .<F'r/150 '-cP LRLF/1501h L I -32- portions of said fibers projecting from the front surface of said backing between said bonding locations, said arcuate portions having a height from said backing of less than about 0.64 centimeters (0.250 inch), and said fibers having a basis weight in the range of 5 to 200 grams per square meter measured along said first surface to provide sufficient open area between said fibers along said arcuate portions to afford ready engagement of said fibers along said arcuate portions by the hook portion of said fastener. 23. A disposable garment according to claim 22 wherein said garment further includes an outer polymeric layer and said rear surface of said backing is adhered to said outer polymeric layer. o 24. A disposable garment according to claim 22 in wherein said 0 disposable garment further includes an outer polymeric layer with a portion of said outer polymeric layer providing said backing for said 00 00) Sloop portion. °0 25. An abrasive disk comprising a layer having first and second surfaces, an abrasive material adhered along said first surface, and a loop portion of a fastener having a hook portion and a loop portion attached along said second surface, said loop portion comprising: a backing having front and rear major surfaces with said rear surface attached along the second surface of said layer; and a multiplicity of fibers having portions bonded to said backing along said front surface at spaced bonding locations to form arcuate 4, portions of said fibers projecting from the front surface of said backing between said bonding locations, said arcuate portions having a height from said backing of less than about 0.64 centimeters (0.250 inch), and said fibers having a basis weight in the range of 5 to 200 grams per square meter measured along said front surface to provide sufficient open area between said fibers along said arcuate portions to afford ready engagement of said fibers along said arcuate portions by the hook portion of said fastener. 26. A sheet material substantially as described herein with reference to Figures 1 to 3 or Figures 9 and 10 of the accompanying drawings. VA 4 RLF/1501h .4l .0 -33- 27. A method for forming a sheet material, said method being substantially as described herein with reference to Figure 4 or Figures and 6 or Figures 7 and 8 of the accompanying drawings. DATED this FIRST day of NOVEMBER 1991 Minnesota Mining and Manufacturing Company Patent Attorneys for the Applicant SPRUSON FERGUSON RLF/1501h