Information
-
Patent Grant
-
6537935
-
Patent Number
6,537,935
-
Date Filed
Friday, January 29, 199925 years ago
-
Date Issued
Tuesday, March 25, 200321 years ago
-
Inventors
-
Original Assignees
-
Examiners
- Morris; Terrel
- Guarriello; John J.
Agents
- Griswold; Gary L.
- Sprague; Robert W.
- Bond; William J.
-
CPC
-
US Classifications
Field of Search
US
- 442 328
- 442 333
- 442 366
- 604 373
- 604 3852
- 428 198
- 428 2981
- 428 92
- 428 152
- 428 195
- 428 196
-
International Classifications
-
Abstract
A nonwoven fabric sheet comprising a multiplicity of generally parallel elongate strands of inelastic thermoplastic material extending in a first direction in spaced relationship, each of said strands having opposite elongate side surface portions that are spaced from and are adjacent elongate side surface portions of adjacent strands, and each of said strands also having corresponding opposite first and second elongate surface portions extending between said opposite elongate side surface portions, and a first sheet of flexible nonwoven material having spaced anchor portions bonded at first bond sites of the strands along said first elongate surface portions wherein the elongate strands thermoplastic material is oriented at least between adjacent bond sites along the length of the strands.
Description
TECHNICAL FIELD
The present invention relates to high strength nonwoven fabric having at least one sheet of flexible nonwoven material intermittently bonded to inelastic filaments. The invention further relates to methods for producing these nonwoven reinforced fabrics in which fibrous webs of low strength are joined to high strength filaments as reinforcing elements.
Nonwoven materials having reinforcing elements are well known in the art. Scrims or like reinforcing webs are often joined to low strength nonwoven webs or fabrics by one of a variety of attachment methods including binders, adhesives, heat or sonic bonding, hydroentanglement or the like. For example, U.S. Pat. No. 4,522,863 describes taking a scrim of crosslaid threads coated with a heat reactable plastisol adhesive and bonds this to a microfiber web, preferably formed by meltblowing. Binders are used in U.S. Pat. No. 4,634,621 to join nonwoven webs to scrims such as Kevlar™ or Nomex™ fabrics. In U.S. Pat. No. 5,691,029, a yarn is bonded to a nonwoven, preferably in a crosshatched pattern. Heat bonding is used in a pattern to bond a microfiber nonwoven to a spunbond scrim in U.S. Pat. No. 4,041,203. A more complete full calendaring is used in U.S. Pat. No. 4,931,355 to join a nonwoven fibrous non-elastic web to a screen, scrim, netting, knit or woven. Hydroentangling also is used in U.S. Pat. No. 4,810,568 to join a nonwoven to a scrim netting. The above applications all employ relatively high strength material joined to a low strength nonwoven web resulting in a web that generally has the strength, flexibility, and other bulk web properties of the high strength material. As such, desirable web properties of the lower strength nonwoven are generally lost, such as flexibility or conformability. This is due to the fact that conventional reinforcement materials are sheet-like materials, as such the sheet or web properties of the composite are dominated by the reinforcement material layer. The composite however will still have surface or bulk properties of an outer nonwoven layer, such as coefficient of friction or absorbency, respectively.
U.S. Pat. No. 5,705,249 discloses bonding filaments to the surface of a nonwoven web. These filaments are pattern bonded by point bonding. This results in bulking of the composite in the area between the point bond sites. This bulking behavior allegedly decreases the slipperiness in comparison to a prior product where the nonwoven was point bonded to a film-like product. This product is complicated to manufacture and the filaments are relatively low strength unoriented type filaments.
It has also been proposed to orient nonwoven webs as a way to provide increased strength in the orientation direction without effecting the softness of the web, U.S. Pat. No. 4,048,364. The fibers forming the web align and provide increased tenacity in this direction of alignment. This process, however, adversely effects the loft and tactile properties of the nonwoven web and does not provide the strength obtainable with a high strength scrim. Also, this process is limited to nonwoven webs having some interfiber bonding or integrity, but not so much that it is filmlike.
Reinforcing scrims or films have also been incorporated into nonwoven web structures or laminates designed for particular end uses. For example, U.S. Pat. No. 5,256,231 describes forming a non-woven or fibrous loop material by corrugating either a non-woven web or a series of substantially non-parallel yarns in a corrugating nip and subsequently extrusion bonding a thermoplastic film onto specific anchor portions of the sheet of corrugated fibrous material.
U.S. Pat. Nos. 5,326,612 and 5,407,439 describe forming loop fastening material from non-woven materials such as spunbond webs lightly bonded to a structural backing. In U.S. Pat. No. 5,326,612, the total bond area (between the fibers of the loop fabric and between the loop fabric and the backing) is between 10 and 35 percent to allow for sufficient open area for the hooks to penetrate. The backing allegedly could be a film, a woven material or a nonwoven but should not allow the hooks to penetrate. In U.S. Pat. No. 5,407,439 the loop fabric (the entanglement zone) is laminated to a material(spacing zone) that permits hooks to penetrate but does not preferably entangle the hooks with a further optional backing layer that does not permit hook penetration. The spacing zone is generally thicker than the entanglement zone such that a hook will not fully penetrate through it. Low bonding levels are desired for these loop fastener applications, as is dimensional stability.
Japanese Pat. Publ. No. 7-313213 describes a loop fastening material formed by fusing one face of a non-woven loop fabric. The fabric is formed by entanglement of sheath-core composite fibers having a polyethylene sheath and a polypropylene core. Generally, the fibers are described as having a diameter of from 0.5 to 10 denier with the non-woven web having a basis weight of from 20 to 200 grams per square meter. The fused face provides reinforcement but this has also adversely affects the softness and flexibility of the fabric.
BRIEF DISCLOSURE OF THE INVENTION
The present invention provides improved inelastic, dimensionally stable, high strength nonwoven fabric sheets comprising a multiplicity of elongate strands of inelastic material extending generally continuously in at least a first direction and one or more sheets of flexible nonwoven material intermittently bonded along at least one elongate surface portion of the inelastic oriented strands. These sheets of nonwoven fabric are not easily extensible, in at least the first direction, due to the elongate strands. Preferably, the sheets have regular spaced bond portions between the nonwoven material and the strands. These intermittent bond anchor portions are separated by unbonded portions where the strand and nonwoven face each other, but not bonded. These composites provide unique advantages as a low cost, flexible or soft, dimensionally stable, breathable nonwoven fabric sheet which is relatively simple to manufacture.
According to the present invention there is also provided a method for forming a nonwoven fabric sheet which comprises (1) providing a first sheet of flexible nonwoven material (e.g., nonwoven web of natural and/or polymeric fibers, and/or yarns); (2) forming the first sheet of flexible nonwoven material to have arcuate portions projecting in the same direction from spaced anchor portions of the first sheet of flexible nonwoven material; (3) extruding or providing spaced generally parallel elongate strands of thermoplastic material that is inelastic (e.g., polyester, polyolefin, nylons, polystyrenes) onto the first sheet of flexible loop material; (4) providing the inelastic strands as a molten mass at least at the spaced anchor portions of the first sheet of flexible nonwoven material to thermally bond the strands to the nonwoven material at bond sites or the anchor portions (the strands extend between the anchor portions of the sheet of flexible nonwoven material with the arcuate portions of the first sheet of flexible material projecting from corresponding elongate surface portions of the strands); and (5) orienting the nonwoven fabric sheet in the longitudinal direction of the strands thereby orienting the strands and reducing or eliminating the arcuate portions. By this method there is provided a novel sheet-like nonwoven composite comprising a flexible nonwoven intermittently bonded to a multiplicity of generally parallel oriented elongate strands of inelastic thermoplastic material extending in one direction in a generally continuous parallel spaced relationship.
BRIEF DESCRIPTION OF DRAWINGS
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:
FIG. 1
is a schematic view illustrating a first embodiment of a method and equipment for making a first embodiment of a nonwoven fabric sheet according to the present invention;
FIGS. 2A and 2B
are perspective views
2
A of a precursor material and
2
B of the first embodiment of the nonwoven fabric sheet according to the present invention made by the method and equipment illustrated in
FIG. 1
;
FIG. 3A
is a fragmentary enlarged sectional view taken approximately along line
3
A—
3
A of
FIG. 2B
;
FIG. 3B
is a fragmentary enlarged sectional view taken approximately along line
3
B—
3
B of
FIG. 2B
;
FIG. 4
is a schematic view illustrating a second-embodiment of a method and equipment for making a second embodiment of a nonwoven fabric sheet according to the present invention;
FIG. 5
is a perspective view of the second embodiment of the nonwoven fabric sheet according to the present invention made by the method and equipment illustrated in
FIG. 4
;
FIG. 6
is a fragmentary enlarged sectional view taken approximately along line
6
—
6
of
FIG. 5
;
FIG. 7
is a fragmentary front view of a die plate included in the equipment illustrated in
FIGS. 1 and 4
;
FIG. 8
is a fragmentary sectional view similar to that of
FIG. 6
which illustrates possible variations in the size and spacing of strands included in the nonwoven fabric sheet;
FIG. 9
is a schematic view illustrating a third embodiment of a method and equipment for making a third embodiment of the nonwoven fabric sheet according to the present invention;
FIG. 10
is a perspective view of the third embodiment of a nonwoven fabric sheet according to the present invention made by the method and equipment illustrated in
FIG. 9
;
FIG. 11
is a perspective view of a fourth embodiment of a nonwoven fabric sheet according to the present invention that can be made by the method and equipment illustrated in
FIG. 9
;
FIG. 12
is a perspective view of a fifth embodiment of a nonwoven fabric sheet such as formed by the first embodiment stretched in the transverse direction;
FIGS. 13 and 14
are both plane views of the first embodiment nonwoven fabric of
FIGS. 2A and 2B
, respectively.
DETAILED DESCRIPTION OF THE INVENTION
The invention composite nonwoven fabric sheet is preferably formed by extruding inelastic strands onto anchor portions of a first sheet of flexible nonwoven material formed to have arcuate portions extending from the anchor portions followed by orientation to provide a strengthened nonwoven. The molten strands form around arcuate surfaces of the anchor portions creating bond sites. The molten strands can form bond sites along all or a part of the strand length where there are anchor portion, (e.g., a flat portion of the nonwoven material). The solidified inelastic strands have a generally uniform morphology along their lengths including at the bond sites prior to orientation. The strands can be pressed against the anchor portions at the bond sites increasing the strand width transverse to the length of the strands (the first direction) which increases the bond strength or attachment area between the sheet and the strands along a first elongate surface portion of the strands. If the strands have flexible nonwoven material attached to only one elongate surface portion the compression and consequential widening of the strands also provides greater surface area for attachment of the nonwoven fabric sheet strands on the second elongate surface portions to a further substrate.
A method for forming a nonwoven fabric sheet with arcuate nonwoven structures between spaced apart bond sites comprises a step of forming the arcuate nonwoven material, which can comprise the following steps. (1) There is provided first and second generally cylindrical corrugating members each having an axis and including a multiplicity of spaced ridges defining the periphery of the corrugating members. The ridges have outer surfaces and define spaces between the ridges adapted to receive portions of ridges of the other corrugating member in meshing relationship with the sheet of flexible material therebetween. The ridges can be in the form of radial or longitudinally spaced parallel ridges or can be intersecting defining regular or irregular shapes with the ridges being linear, curved, continuous or intermittent. (2) The corrugating members are mounted in axially parallel relationship with portions of the opposing ridges in meshing relationship. (3) At least one of the corrugating members is rotated. (4) The sheet of flexible nonwoven material is fed between the meshed portions of the ridges to form the sheet of flexible nonwoven material on the periphery of one of the corrugating members. This forms arcuate portions of the sheet of flexible nonwoven material in the spaces between the ridges of a first corrugating member and anchor portions of the sheet of flexible nonwoven material along the outer surfaces of the ridges of the first corrugating member. (5) The formed sheet of flexible nonwoven material is retained along the periphery of the first corrugating member for a predetermined distance after movement past the meshing portions of the ridges. Following forming the arcuate nonwoven material, the inelastic strands are extruded in an extruding step which includes providing an extruder that, through a die with spaced die openings, extrudes the spaced strands of molten thermoplastic material onto the anchor portions of the sheet of flexible nonwoven material along the periphery of the first corrugating member within the above mentioned predetermined distance. The strand and nonwoven fabric composite is then oriented causing the strand material to undergo molecular orientation between the spaced apart bond sites.
The dimensions of the strands can be easily varied by changing the pressure in the extruder from which the strands are extruded (e.g., by changing the extruder screw speed or type); changing the speed at which the first corrugating member, and thereby the first sheet material, is moved (i.e., for a given rate of output from the extruder increasing the speed at which the sheet of flexible nonwoven material is moved will decrease the diameter of the strands, whereas decreasing the speed at which the sheet of nonwoven material is moved will increase the diameter of the strands); or changing the dimensions of the spaced die openings. The die through which the extruder extrudes the thermoplastic inelastic strand material can have an easily changeable die plate in which are formed the row of spaced openings through which the strands of molten thermoplastic material are extruded. Such interchangeable die plates, with openings of different diameters and different spacings, can be formed by electrical discharge machines or other conventional techniques. Varied spacing and/or diameters for the openings along the length of the die plates can be used to affect tensile strength at various locations across the composite, vary anchorage of the nonwoven material to the strands or increase surface area on the opposing elongate surface portion of the strands available for bonding the nonwoven fabric sheet to further substrates. The die can also be used to form hollow strands, strands with shapes other than round (e.g., square or + shaped) or bi-component strands.
The nonwoven fabric sheet can further include a second sheet of flexible nonwoven material having anchor portions thermally bonded at second bond sites. These second bond sites can also be longitudinally spaced along second elongate surface portions of the inelastic strands and have arcuate portions projecting from the second elongate surface portions of the inelastic strands between the second sheet bond sites.
Using the method described above, such a second sheet of flexible nonwoven material can also have arcuate portions. The second sheet of flexible nonwoven material arcuate portions can also project from spaced anchor portions of the second sheet of flexible nonwoven material. The spaced anchor portions of the second sheet of flexible nonwoven material are then positioned in closely spaced opposition to spaced anchor portions of the first sheet of flexible nonwoven material with the arcuate portions of the first and second sheets of flexible nonwoven material projecting in opposite directions. The spaced generally parallel elongate strands of molten thermoplastic inelastic strand material are then extruded between and onto the anchor portions of both the first and second sheets of flexible nonwoven material to form inelastic strands bonded to and extending between the anchor portions of both the first and second sheets of flexible nonwoven material.
In an alternative embodiment the spaced generally parallel elongate strands can be preformed and supplied onto the anchor portions along the periphery of the first corrugating member as described above. The corrugating member or a roll opposite the corrugating member, forming a nip, is heated so that the preformed strands are softened or melted and pressed against the anchor portions at the bond sites as described above. These preformed strands can be used in any of the contemplated embodiments of the invention where strands are provided by extrusion.
The composite nonwoven fabric sheets formed by the above described embodiments and elsewhere in this specification are then oriented or stretched in the longitudinal direction of the strands. This is preferably done while heating to soften the strands sufficient to allow orientation without strand breakage, particularly at the bond sites. This stretching causes molecular orientation to occur in the strand material preferably in the unbonded portions of the strands between the bond sites. The arcuate portions height becomes less as the distance between the bond sites increases due to the strand orientation. This can reduce or eliminate the projecting arcuate portions to create a substantially flat nonwoven fabric sheet with multiple oriented strengthened strands intermittently bonded to the nonwoven material along the length of the oriented strands. Preferably, the length of the flexible nonwoven material between the bond sites is substantially equal to the distance between the bond sites following the orientation step. This is done by stretching the composite nonwoven up to its allowable stretch(as defined in the examples), however the composite can be stretched beyond the allowable stretch provided that the bond sites to not orient significantly (e.g. more than 100 percent, preferably more than 50 percent).
Either or both of the first and second sheets of flexible nonwoven material(s) in the nonwoven fabric sheet can be a conventional web of nonwoven fibers or a multi-layer composite of nonwoven materials; for example carded webs, spunlaced webs, melt-blown webs, Rando webs, or laminates thereof. Also relatively strong nonwovens such as spunbond type webs or other highly consolidated webs can be used. The fibers forming the nonwoven material could be formed of natural or synthetic fibers such as polypropylene, polyethylene, polyester, nylon, cellulose, or polyamides, or combinations of such materials, such as a multicomponent fiber (e.g., a core/sheath fiber such as a core of polyester and a sheath of polypropylene which provides relatively high strength due to its core material and is easily bonded to polypropylene strands due to its sheath material). Fibers of different materials or material combinations may also be used in the same sheet of nonwoven material. One preferred type of nonwoven material having random arcuate portions is one where a fibrous web has been processed to have random arcuate portions by the “Microcreping Process for Textiles” using the “Micrex/Microcreper” equipment available from Micrex Corporation, Walpole, Mass., that bears U.S. Pat. Nos. 4,894,169; 5,060,349; and 4,090,385. In the microcreping process, the sheet of nonwoven material is randomly folded and compressed in a first direction along its surfaces. With a microcreped or like nonwoven web, the corrugating steps are not needed and the material can be directly joined to the thermoplastic strands. The anchor portions and arcuate portions are created by the microcreping processing.
Generally, sheets of flexible nonwoven material should be of polymeric material that can thermally bond with the thermoplastic strand material at the temperature of the extrudate or the bond temperature. Preferably, the sheets of nonwoven material and the thermoplastic strand material are formed from the same type of thermoplastic material to enhance bonding of the nonwoven material to the strands and also allowing for recycling. For example, in a preferred embodiment, the flexible nonwoven material would be formed in whole or in part of polypropylene fibers with the strands also formed of polypropylene allowing for increased anchorage between the strands and the fibers forming the flexible nonwoven material. Generally, both the strands and at least a portion of the flexible nonwoven material fibers are polyolefin materials, preferably compatible polyolefins.
FIG. 1
schematically illustrates a first embodiment of a method and equipment for making a first embodiment of a nonwoven fabric sheet
10
according to the present invention, which is illustrated in
FIGS. 2B and 3
.
Generally the method illustrated in
FIG. 1
involves providing a first sheet
12
of flexible nonwoven material. The first sheet
12
of flexible nonwoven material is folded to have multiple arcuate portions
13
projecting in the same direction from spaced anchor portions
14
of the first sheet
12
of flexible nonwoven material. Spaced generally parallel elongate strands
16
a
of molten thermoplastic inelastic material are extruded onto the anchor portions
14
of the first sheet
12
of flexible nonwoven material to form inelastic strands
16
. The inelastic strands are thermally bonded to the anchor portions
14
forming bond sites and extend in the arcuate portion areas between the anchor portions
14
of the first sheet
12
of flexible nonwoven material. As such the multiple arcuate portions
13
of the first sheet
12
of flexible nonwoven material project from the elongate surface portions
18
of the strands
16
as shown in FIG.
2
A. The strands are then cooled, solidified, and oriented to provide a high strength flexible nonwoven fabric sheet
10
as shown in FIG.
2
B. The orientation step is generally done with applied heat to soften the strands during orientation. The arcuate portions
13
have been flattened due to the orientation of the strands
16
between roll
15
and roll
17
, both of which may be driven. Roll
17
is overdriven relative to roll
15
to orient the nonwoven fabric sheet
10
.
As illustrated in
FIG. 1
, equipment for performing the above method includes first and second generally cylindrical corrugating members
20
and
21
each having an axis and including a multiplicity of spaced ridges
19
defining the periphery of the corrugating members
20
or
21
. The ridges
19
have outer surfaces with spaces defined between the ridges
19
adapted to receive portions of the ridges
19
of the opposing corrugating member in meshing relationship, with the first sheet
12
of flexible nonwoven material therebetween. A means is provided for mounting the corrugating members
20
and
21
in axially parallel relationship with portions of the ridges
19
in meshing relationship. A means is provided for rotating at least one of the corrugating members
20
or
21
. A sheet
12
of flexible nonwoven material is fed by the rotating corrugating member(s)
20
or
21
between the meshed portions of the ridges
19
the sheet
12
. The flexible nonwoven material will generally conform to the periphery of one of the corrugating members(e.g.
20
). This forms the arcuate portions
13
of the first sheet
12
of flexible material in the spaces between the ridges
19
of this first corrugating member
20
and also forms the anchor portions
14
along the outer surfaces of the ridges
19
of the first corrugating member
20
. There is also provided a means for retaining the formed sheet
12
of flexible material along the periphery of the first corrugating member
20
for a predetermined distance after the sheet has moved past the meshing portions of the opposing ridges
19
. This means could include the surface of the first corrugating member
20
being roughened, e.g. by being sand blasted or chemically etched, or a vacuum, or being heated to a temperature above the temperature of the first sheet
12
of flexible nonwoven material, generally in the range of 25 to 150 Fahrenheit degrees above the nonwoven material temperature. An extruder feeds a die
22
, which can be provided with a changeable die plate
23
(see
FIG. 7
) with spaced through openings
40
. The extruder and die plate form a multiplicity of generally parallel elongate molten strands
16
a
of the thermoplastic material (e.g., polyester, polystyrene, polyolefin, nylons, coextruded materials or the like as discussed above) extending continuously in a generally parallel spaced relationship. The extruder and die are further positioned so that the molten strands
16
a
are extruded onto the anchor portions
14
of the first sheet
12
of flexible material along the periphery of the first corrugating member
20
within the above mentioned predetermined distance. Also, the equipment further includes a generally cylindrical cooling roll
24
having an axis with means for rotatably mounting the cooling roll
24
in axially parallel relationship with the corrugating members
20
and
21
. The periphery of the cooling roll
24
is closely spaced from the periphery of the first corrugating member
20
defining a nip. At a second predetermined distance, there is a means provided (e.g., a nipping roller
25
) for moving the nonwoven fabric sheet
10
for the second predetermined distance around the periphery of the cooling roll
24
past the nip. The strands
16
in this area contact the cooling roll
24
cooling and solidifying the strands
16
. The nonwoven fabric sheet is then fed to an orienting station, which can be a idler roll
15
and a nipped driven roll
17
driven at a speed faster than that of cooling roll
24
, to orient the strands
16
at least in the unbonded portion
11
between the bond sites
27
. Alternatively, the nonwoven fabric sheet could be only selectively oriented in regions as disclosed in U.S. Pat. No. 5,424,025, the substance of which is incorporated by reference in its entirety.
The structure of the nonwoven fabric sheet
10
made by the method and equipment illustrated in
FIG. 1
is best seen in
FIGS. 2A
,
2
B,
3
A and
3
B. The nonwoven fabric sheet
10
comprises a multiplicity of generally parallel elongate strands
16
of inelastic thermoplastic material extending continuously in a generally parallel spaced relationship. Each of the strands
16
is generally cylindrical and has opposite elongate side surface portions
26
(See
FIG. 3A
) that are spaced from and are adjacent the elongate side surface portions
26
of adjacent strands. Each of the strands
16
also has corresponding opposite first and second elongate surface portions
18
and
28
extending between the opposite elongate side surface portions
26
. The spaced anchor portions
14
of the sheet
12
of flexible nonwoven material are thermally bonded at sheet bond sites
27
to longitudinally spaced parts of the strands
16
along the first elongate surface portions
18
. The flexible nonwoven material arcuate portions
13
have been flattened and contact, but are not bonded to, the first elongate surface portions
18
of the oriented inelastic strands
16
in the unbonded regions
11
between the first sheet bond sites
27
.
In
FIGS. 2A and 2B
, the sheet bond sites
27
are spaced about the same distances from each other and aligned in generally parallel rows extending transverse of the strands
16
. Because the strands
16
have been extruded in molten form onto the anchor portions
14
of the sheet
12
of flexible nonwoven material the strands can be pressed onto the anchor portions
14
of the sheet
12
by adjusting the nip spacing between the ridges
19
on the first corrugating member
20
and the periphery of the cooling roll
24
. The compressed molten strands
16
can form around and are indented by the arcuate convex surfaces of the anchor portions
14
. The bonds between the strands
16
and the anchor portions
14
at the first sheet bond sites
27
can extend outward depending on the compression of the molten strands at the anchor portion. As is illustrated in
FIG. 3B
, the strand surface at the bond site
27
, that is closely adjacent the anchor portions
14
, is widened by the indentations of the strands
16
.
FIG. 4
illustrates a second embodiment of a method and equipment for making a second embodiment of a nonwoven fabric sheet
30
according to the present invention, which sheet
30
is illustrated in
FIGS. 5 and 6
. The method illustrated in
FIG. 4
is somewhat similar and uses much of the same equipment as is illustrated in
FIG. 1
, and similar portions of that equipment have been given the same reference numerals and perform the same functions as they do in the equipment illustrated in FIG.
1
. In addition to the general method steps described above with reference to
FIG. 1
, the method illustrated in
FIG. 4
further generally includes the steps of providing a second sheet of nonwoven material
32
. The second sheet
32
of nonwoven material is formed to have multiple arcuate portions
33
projecting in the same direction from spaced anchor portions
34
of the second sheet
32
of nonwoven material. The spaced anchor portions
34
of the second sheet
32
of nonwoven material are positioned in closely spaced opposition to the spaced anchor portions
14
of the first sheet
12
of flexible nonwoven material with the arcuate portions
13
and
33
of the first and second sheets
12
and
32
of nonwoven material projecting in opposite directions. The extruder die
23
extrudes the spaced generally parallel elongate strands
16
a
of molten thermoplastic inelastic material between and onto the anchor portions
14
and
34
of both the first and second sheets
12
and
32
of nonwoven material to form inelastic strands
16
bonded to and extending between the anchor portions
14
and
34
of both the first and second sheets
12
and
32
of nonwoven material. The arcuate portions
13
and
33
of the first and second sheets
12
and
32
of nonwoven material project in opposite directions from opposite corresponding first and second elongate surface portions
18
and
28
of the strands
16
prior to orientation of the fabric sheet which flatten the arcuate portions between the bond sites created at the anchor portions.
The equipment illustrated in
FIG. 4
, in addition to the first and second corrugating members
20
and
21
, and the extruder
22
, which are operated in the manner described above with reference to
FIG. 1
, further includes third and fourth generally cylindrical corrugating members
36
and
37
which operate as described above relative to corrugating members
20
and
21
. The third corrugating member
36
is positioned in spaced relationship from the first corrugating member
20
so that the extruder die
22
positions the molten strands
16
a
on the anchor portions
14
and
34
of both the first and second sheets
12
and
32
of loop material along the peripheries of the first and third corrugating members
20
and
36
within the above mentioned predetermined distance. Air ducts
39
are provided to blow streams of cool air against opposite sides of the nonwoven fabric sheet
30
to solidify the strands
16
a
and the bond between the strands
16
a
and the anchor portion
14
and
34
of the sheets
12
and
32
. The solidified fabric sheet is then oriented between idler roll
15
and nipped driven roll
17
to orient the strands at least in the unbonded regions
11
between bond sites
27
and
47
as described relative to the first embodiment method and equipment illustrated in FIG.
1
.
The structure of the second embodiment nonwoven fabric sheet
30
made by the method and equipment illustrated in
FIG. 4
is best seen in
FIGS. 5 and 6
. The nonwoven fabric sheet
30
comprises the multiplicity of generally parallel elongate strands
16
of inelastic thermoplastic material extending in generally parallel spaced relationship. Each of the strands
16
has opposite elongate side surface portions
26
(See
FIG. 6
) that are spaced from and are adjacent the elongate side surface portions
26
of adjacent strands. Each of the strands
16
also has corresponding opposite first and second elongate surface portions
18
and
28
extending between its opposite elongate side surface portions
26
. The spaced anchor portions
14
of the first sheet
12
of flexible nonwoven material are thermally bonded at first sheet bond sites
27
to longitudinally spaced parts of the strands
16
along their first elongate surface portions
18
, and the arcuate portions
13
of the first sheet
12
of flexible material are flattened in the unbonded region
11
where the strands have been elongated. The second sheet
32
of nonwoven material has its spaced anchor portions
34
thermally bonded at second spaced sheet bond sites
47
to longitudinally spaced parts of the strands
16
along the second elongate surface portions
28
, and has its arcuate portions
33
flattened in the unbonded region
11
where the strands have been elongated. The first and second sheet bond sites (
27
and
47
) are opposed to each other, are spaced about the same distances from each other, and are aligned in generally parallel rows extending transverse of the strands
16
. Because the strands
16
have been extruded in molten form onto the anchor portions
14
and
34
of both the first and second sheets
12
and
32
, the molten strands
16
can form around and be indented on opposite elongate surface portions by the arcuate convex adjacent surfaces of the anchor portions
14
and
34
. The bonds between the strands
16
and the anchor portions
14
and
34
at the first and second sheet bond sites (
27
and
47
) as above can extend outward in the area adjacent the anchor portions
14
and
34
as shown in FIG.
3
B.
Alternative structures that could be provided for the nonwoven fabric sheet
30
(in addition to the alternate structures noted above for the nonwoven fabric sheet
10
) include spacing the anchor portions
14
of the first sheet
12
and the anchor portions
34
of the second sheet
32
at different spacings along the strands
16
and/or causing the continuous rows of the arcuate portions
13
and
33
to project at different distances from the first and second elongate surface portions
18
and
28
of the strands
16
; or causing one of the sheets
12
or
32
to be discontinuous along its length, or across its width.
FIG. 7
illustrates the face of the die
22
through which the molten strands
16
a
of thermoplastic material are extruded. The die
22
has spaced openings
40
(e.g., 0.762 millimeter or 0.03 inch diameter openings spaced 2.54 millimeter or 0.1 inch center to center) in its die plate
23
preferably formed by known electrical discharge machining techniques. The die plate
23
is retained in place by the bolts
41
, and can be easily replaced with a die plate with openings of different or varied sizes, which openings are spaced on different or varied centers to produce a desired pattern of strands from the die
22
.
FIG. 8
illustrates a nonwoven fabric sheet
30
b
similar to that illustrated in
FIGS. 5 and 6
and in which similar parts are identified with similar reference numerals except for the addition of the suffix “b”.
FIG. 8
shows one of many possible variations in the spacing and diameters of the strands
16
b
. The strands can be round, square, rectangular, oval, or any other shape. The elongate surface portions of the strands attached to the oriented nonwoven sheet material generally comprises from 2 to 70 percent of the cross sectional surface area of the nonwoven fabric sheet, preferably 5 to 50 percent. This permits sufficient surface area for the nonwoven fabric sheet to be further attached to a substrate and still have the required tensile strength as well as breathability, flexibility, and other bulk properties of the nonwoven material.
Generally, the nonwoven fabric sheet should have a tensile strength in the lengthwise direction of the strands of at least 2000 grams/2.54 cm-width, preferably at least 4000 gram/2.54 cm-width. Low tensile strengths decrease dimensional stability.
FIG. 9
illustrates a third embodiment of a method and equipment that can be used for making third and fourth embodiments of nonwoven fabric sheet
90
and
100
according to the present invention, respectively illustrated in
FIGS. 10 and 11
.
The equipment illustrated in
FIG. 9
includes first and second generally cylindrical bonding rollers
82
and
83
each having an axis and a periphery around that axis defined by circumferentially spaced ridges
85
generally parallel to the axes of the bonding rollers
82
and
83
. The bonding rollers
82
and
83
define a nip. Compacting devices
86
and
87
(e.g., the devices commercially designated “Micrex/Microcreper” equipment available from the Micrex Corporation, Walpole, Mass., which crinkles and compresses the fibers or material of a sheet to form a sheet that is compacted in a first direction along its surfaces)are adapted for receiving a sheet
88
or
89
of flexible nonwoven material having opposite major surfaces. These compacting devices compact sheet
88
or
89
in a first direction parallel to its major surfaces (i.e., along its direction of travel through the device
86
or
87
) so that the first and second compacted sheets
91
and
92
have opposite surfaces and can be extended in the first direction along those surfaces in the range of 1.1 to over 4 times its compacted length in the first direction. Means are provided for feeding the first and second compacted sheets
91
and
92
of flexible nonwoven material into the nip formed by the first and second bonding rollers
82
and
83
. An extruder
83
that is essentially the same as the extruder
22
described above, extrudes inelastic thermoplastic material strands in generally parallel spaced relationship and are positioned between the opposed surfaces of the first and second compacted sheets
91
and
92
of flexible material in the nip between the first and second bonding rollers
82
and
83
. The strands
95
extending in the first direction along the first and second compacted sheets
91
and
92
are thermally bonded to the first and second compacted sheets
91
and
92
at spaced bond sites
96
along the strands
95
because of bonding pressure applied by the ridges
85
. The nonwoven fabric sheet
90
is retained along the periphery of the bonding roller
82
by a guide roller
97
, and the bonding roller
82
is cooled (e.g., to 100 degrees Fahrenheit) to help solidify the strands
95
. The nonwoven fabric
10
is oriented between idler roll
15
and nipped driven roll
17
as described relative to the first embodiment of FIG.
1
.
The nonwoven fabric sheet
90
made by the mechanism illustrated in
FIG. 9
is illustrated in FIG.
10
. That nonwoven fabric sheet
90
comprises a multiplicity of the generally parallel elongate extruded strands
95
of inelastic thermoplastic material extending in generally parallel spaced relationship. Each of the strands
95
having opposite elongate side surface portions that are spaced from and are adjacent the elongate side surface portions of adjacent strands
95
, and each of the strands
95
also having corresponding opposite first and second elongate surface portions extending between the opposite elongate side surface portions. The first and second compacted and extended sheets
91
and
92
of flexible nonwoven material have opposite major surfaces. Those first and second compacted and extended sheets
91
and
92
are respectively thermally bonded to the first and second elongate surface portions of the strands
95
at the closely spaced bond sites
96
.
The equipment illustrated in
FIG. 9
can be operated with only one of the sheets
88
or
89
of flexible nonwoven material, in which case it will make a nonwoven fabric sheet like the nonwoven fabric sheet
100
illustrated in FIG.
11
. Alternatively, one of the sheets of nonwoven material
88
or
89
in the
FIG. 9
equipment could be replaced by a spunlace scrim
99
, or like low loft orientable breathable material which could be fed without feeding through a compacting device
86
or
87
.
The strand
16
illustrated in the above embodiments are essentially continuous and parallel in the longitudinal or machine direction of the composite nonwoven material. Additionally, the strands could extend substantially non-parallel, each with respect to the other provided that the overall web inextensibility is not significantly effected. Further, the arcuate portions of the sheet flexible material formed by the methods illustrated above could be in the form of circles, diamonds, rectangular shapes or other regular or irregular patterns through the use of suitable intermeshing corrugating members with rigid elements. Preferably, the bond sites of the anchor portions are spaced each from the other along the length of the inelastic strand materials by a distance of on average 2 mm to 200 mm, preferably, 5 mm to 100 mm prior to orientation and from 4 to 1000 mm, preferably 5 to 500 mm after orientation of the composite sheet material.
The inelastic strands
16
could also be provided as preformed strands which could be unwound from multiple bobbins or other wound rolls and fed into a comb or like structure to distribute the strands along the width of a heated nip which would thermally bond the preformed inelastic strands to the flexible nonwoven material. For example, in the embodiment depicted in
FIG. 1
, the ridge members
19
on the first corrugating member
20
could be heated or serve as an anvil for an ultrasonic bonder to thermally point bond the preformed strands to the anchor portions of the flexible nonwoven material
12
.
With any of the above described embodiments, additional layers could be incorporated. For example, in the embodiment depicted in
FIG. 9
, either of compacting devices
87
or
86
could be omitted, instead replaced by providing an uncompacted sheet of film or a variety of easily extensible material including lightly bonded extensible non-woven webs. These additional web materials could also be printed on one or both side to provide suitable aesthetic or informational messages. Printing could also be performed on the formed nonwoven fabric sheet by printing the flexible nonwoven material on either surface, either before or after it is attached to the inelastic strand material
16
.
In the embodiment of
FIG. 12
, the material of
FIG. 2B
has been stretched transverse(T) to the longitudinal direction(L) of the oriented inelastic strand
16
. This results in the nonwoven material contracting in the longitudinal direction(L) by necking. The strands
16
as such are buckled between the spaced anchor portions bond sites
27
causing the strands to bend outward in the unbonded regions
11
. The strand
16
length between the bond sites is greater than the length of the compacted or contracted flexible nonwoven between the bond sites. These bent loop portions
116
provide upstanding projections extending from the surface of the substantially flat flexible nonwoven
12
. These strand projections
116
can be used to create a spacer element to separate the nonwoven material
12
from a surface in which the composite is in contact. The strand projections can also provide a material with significant loft or can engage with suitable mechanical fastener elements. The nonwoven material for this embodiment must be neckable, meaning that it must shrink in size in the direction transverse to the direction in which it is elongated. Suitable neckable nonwoven webs include spunbond webs, bonded carded webs, melt blown fiber webs and the like.
The composite nonwoven material of the invention finds particular advantageous use as medical wraps, interliners, absorbents, geotextiles, wipes, or the like. The material has high strength in the machine direction yet still retains its breathable nature and its conformability in both the cross and machine direction. The orientation step results in molecular orientation of the molecules of the inelastic strand material thereby significantly enhancing the tensile strength of the composite. The phenomenon of molecular orientation upon orienting is well understood. Since the fibrous portions are arcuate prior to orientation they do not undergo substantial deformation during the orienting step if the level of orientation is maintained to the extent where the arcuate portions are rendered substantially flat. The nonwoven material can easily flex and conform and withstand flexural forces. The invention process actually decreases the percent bond area increasing the permeability and openness In a particular preferred embodiment, the nonwoven fabric sheet material could be supplied in a roll form cut into appropriate shapes on a continuous production line and integrated into an assembly with suitable attachment methods including ultrasonic bonding, heat bonding, hot melt, or pressure sensitive adhesive attachment.
Generally, it is desirable to have the bond sites stretch less than 100 percent and most preferably less than 50 percent. With relatively higher strength (e.g., strengthen by calandering or like bonding) nonwovens it is possible to have the bond site stretch by less than 5 percent (e.g., spunbonded nonwovens). The strand material between the bond sites is generally oriented at least 15 percent, preferably at least 50 percent, and most preferably at least 90 percent, resulting in molecular orientation of the strand thermoplastic material. The strand material between the bond sites should be significantly more oriented than the strand material at the bond sites. Generally at least 15 percent more, most preferably at least 50 percent more.
EXAMPLES
Example 1
An inelastic fabric sheet composite similar to the sheet-like composite
10
illustrated in
FIG. 2A
was made using equipment similar to that illustrated in
FIG. 1. A
thermoplastic ethylene-propylene impact copolymer commercially available under the designation 7C50 from the Union Carbide Corporation of Danbury, Conn. was placed in the extruder
22
to form substantially parallel inelastic strands
16
at approximately 4.7 strands per cm. The strands, at a basis weight of 40 grams per square meter, were applied by the equipment to a corrugated first sheet
12
of carded nonwoven material formed from 6 denier polypropylene staple fibers commercially available under the designation J01 from Amoco Fabric and Fibers Company of Atlanta, Ga. The carded nonwoven sheet had a basis weight of 55 grams per square meter after corrugation. The nonwoven sheet
12
was corrugated in the cross direction between the corrugation rollers
20
and
21
to form approximately 3 linear corrugations per centimeter, then bonded to the extruded strands
16
in the nip between the corrugation roll
20
and the chill roll
24
. The corrugation roll
20
was at about 93° C.; the corrugation roll
21
was at about 149° C., and the chill roll
24
was at about 21° C. The line speed was about 18 meters per minute, and the melt temperature in the extruder
22
was about 260° C. The resulting inelastic nonwoven fabric sheet composite produced had arcuate nonwoven portions
13
about 2 mm in height projecting from the strands.
The strands
16
between the bond sites were then oriented longitudinally with application of heat and tension. A 7.6-cm wide by 10.2-cm long sample was stretched approximately 91% while being heated with a Master Heat Gun Model HG-751B available from the Master Appliance Corp. of Racine, Wis. to soften the inelastic strands. The heat gun was set on high and held approximately 25 centimeters from the sample while it was being stretched. The temperature of the hot air during stretching was approximately 50° C., as measured with a thermometer held in close proximity to the sample. During the stretching operation, the inelastic strands between the bond sites orient longitudinally resulting in the arcuate nonwoven portions being rendered flat as shown in FIG.
2
B. The strands do not orient in the bond site regions to any appreciable extent providing the strands are not stretched beyond the point where the arcuate nonwoven portions are rendered flat, also referred to as percent (%) allowable stretch. The percent allowable stretch of the nonwoven fabric composite before the strand orientation step, was calculated by measuring the arc length A
o
of the arcuate nonwoven portions between two bond sites of the nonwoven fabric sheet composite, subtracting the length of the strand between the two bond sites S
o
from the result, dividing the result by the length of the strand S
o
between the two bond sites, and then multiplying by 100 to convert the result to a percentage. The percent orientation or stretch was calculated by measuring the lengths of the inelastic strands between the bond sites S
o
and S′, before and after orientation. The increase in strand length was divided by the original unoriented strand length and the result multiplied by 100 to convert to a percentage. Percent orientation and percent available stretch are shown in Table 1 below. The lengths of the bonding sites B
o
and B′, shown in
FIGS. 13 and 14
, were also measured before and after stretching to determine if the composite had been stretched beyond the point where the arcuate nonwoven portions are rendered flat. The results are shown in Table 2 below. Following the longitudinal orientation, the oriented composite was tested for tensile strength as described in “Test Methods” below. The data obtained is shown in Table 3.
Example 2
An inelastic nonwoven fabric sheet composite was prepared similar to the composite in Example 1 except 30 denier polypropylene staple fibers commercially available under the designation J01 from Amoco Fabric and Fibers Company of Atlanta, Ga. were used to form the corrugated nonwoven sheet at a basis weight of 55 grams per square meter. A strand count of 9.4 strands per centimeter at a basis weight of 50 grams per square meter was used. The inelastic sheet-like composite produced had arcuate nonwoven portions 13 about 1.6 mm in height projecting from the strands. The strands between the bond sites were then oriented approximately 92% using the same procedure as in Example 1. The lengths of the bonding sites were also measured before and after stretching. The inelastic composite was tested for tensile strength before and after the orientation step.
Comparative Example 1
An inelastic nonwoven fabric sheet-like composite was prepared as in Example 2 and the strands between the bond sites oriented using the same procedure as in Example 1 except the strands were oriented approximately 330% to demonstrate the effect of stretching the composite significantly beyond the point where the arcuate nonwoven portions are rendered flat. This material has high tensile strength due to the high level of orientation in the strands, however the bond sites have stretched considerably also (approximately 130%) resulting in unbonded, minimally bonded and/or broken fibers which compromise web integrity, homogeneity and appearance. Once the bond areas are reduced substantially due to orienting, the fibers have minimal anchorage and the composite has an undesirable nonuniform appearance. The lengths of the bonding sites were also measured before and after stretching. The composite was tested for tensile strength before and after the orientation step.
Example 3
An inelastic nonwoven fabric sheet-like composite was prepared as in Example 1 except 18 denier polypropylene staple fibers commercially available under the designation J01 from Amoco Fabric and Fibers Company of Atlanta, Ga. were used to form the corrugated nonwoven sheet. A strand count of 9.4 per cm was used at a basis weight of 50 grams per square meter. The corrugation periodicity was approximately 4 corrugations per centimeter. The sheet-like composite produced had arcuate nonwoven portions about 1.60 mm in height projecting from the strands. The strands between the bond sites were then oriented approximately 104% using the same procedure as in Example 1. The lengths of the bonding sites were also measured before and after stretching. The inelastic composite was tested for tensile strength before and after the orientation.
Example 4
An inelastic nonwoven fabric sheet-like composite was prepared as in Example 1 except a 30 grams per square meter basis weight spunbonded type polypropylene nonwoven available from Amoco Fabrics and Fibers Company of Atlanta, Ga., under the designation ‘RFX’ was used in place of the carded nonwoven web. A strand count of 9.4 strands per cm was used at a basis weight of 50 grams per square meter. The sheet-like composite produced had arcuate nonwoven portions about 2.0 mm in height projecting from the strands. The strands between the bond sites were then oriented approximately 100% using the same procedure as in Example 1. The lengths of the bonding sites were also measured before and after stretching. The composite was tested for tensile strength before and after the orientation.
Example 5
An inelastic nonwoven fabric sheet-like composite was prepared as in Example 1 except hexagonal pattern embossing rolls were used in place of the corrugating rolls as described in PCT Application No. WO 98/06290. 18 denier polypropylene staple fibers commercially available under the designation J01 from Amoco Fabric and Fibers Company of Atlanta, Ga. were used to form the carded nonwoven into which a hexagonal pattern was embossed with each side of the hexagon being approximately 3 mm long. A strand basis weight of 50 grams per square meter was used. The sheet-like composite produced had arcuate nonwoven portions about 1.34 mm in height projecting from the strands. The strands between the bond sites were then oriented using the same procedure as in Example 1. The composite was tested for tensile strength before and after the orientation step.
Example 6
An inelastic nonwoven fabric sheet-like composite was prepared as in Example 4 and then the strands between the bond sites were oriented approximately 100% using the same procedure as in Example 1. The resulting oriented composite was then stretched 10% in the transverse or cross direction which resulted in the oriented strands
11
being projected upwards from the nonwoven layer to form arcuate portions approximately 0.85 mm in height as shown in FIG.
12
.
TEST METHODS
To evaluate the tensile strength of the inelastic composites of this invention, tensile testing was performed using a modified version of ASTM D882 with an Instron Model 5500R constant rate of extension tensile machine. A sample was cut from the composite, 2.54 cm wide by 10.16 cm long, the long direction being in the machine or longitudinal direction. The sample was mounted in the jaws of the test machine with an initial jaw separation of 2.54 cm. The jaws were then separated at a rate of 5 cm/min and the yield point recorded.
Three replicates were tested and averaged for each test result.
TABLE 1
|
|
Strand
Strand
Percent
|
length
length
Percent
Allowable
|
before
after
Orientation
Stretch
|
orientation
orientation
[(S′ − S
o
)/
[(A
o
− S
o
)/
|
Example
S
o
(mm)
S′ (mm)
S
o
] × 100
S
o
] × 100
|
|
|
1
2.85
5.44
91%
84%
|
2
2.67
5.13
92%
115%
|
Comp. 1
2.67
11.43
328%
115%
|
3
2.04
4.17
104%
88%
|
4
2.37
4.75
100%
96%
|
5
4.87
5.69
17%
31%
|
|
TABLE 2
|
|
Bond site
|
length
Bond site
|
before
length after
Percent Bond site
|
orientation
orientation B′
stretch
|
Example
B
o
(mm)
(mm)
[(B′ − B
o
)/B
o
] × 100
|
|
1
0.81
1.15
42%
|
2
0.88
1.33
51%
|
Comp. 1
0.88
2.02
130%
|
3
0.68
0.93
37%
|
4
1.04
1.04
0.0%
|
5
0.69
1.26
83%
|
|
TABLE 3
|
|
Percent
|
Yield tensile
Yield tensile
increase
|
strength before
strength after
in yield
|
orientation
orientation
tensile
|
Example
(grams/25.4 mm)
(grams/25.4 mm)
strength
|
|
|
1
1640
2960
81%
|
2
2010
3810
90%
|
Comp. 1
2010
5310
164%
|
3
1890
2770
47%
|
4
2530
4950
96%
|
5
1890
2760
46%
|
|
Claims
- 1. A nonwoven fabric sheet comprising:a multiplicity of generally parallel elongate strands of inelastic thermoplastic material extending in a first direction in spaced relationship, each of said strands having opposite elongate side surface portions that are spaced from and are adjacent elongate side surface portions of adjacent strands, and each of said strands also having corresponding opposite first and second elongate surface portions extending between said opposite elongate side surface portions; and a first sheet of flexible nonwoven material formed of fibers, having spaced anchor portions bonded at first bond sites of the strands along said first elongate surface portions wherein the thermoplastic material forming the strands is oriented by stretching the strands at least between adjacent bond sites along the length of the strands.
- 2. The nonwoven fabric sheet of claim 1 where the nonwoven fabric sheet has a tensile yield strength in the first direction of at least 2000 grams/2.54 cm-width.
- 3. The nonwoven fabric sheet of claim 1 wherein the nonwoven fabric sheet has a second web attached to the second elongate surface portion.
- 4. The nonwoven fabric sheet of claim 1 wherein the nonwoven fabric sheet has a tensile yield strength in the first direction of at least 4000 g/2.54 cm-width.
- 5. The nonwoven fabric sheet of claim 1 wherein the strands at the bond sites are less oriented than the strands between the bond sites.
- 6. The nonwoven fabric sheet of claim 1 wherein the bond sites are from 2 to 70 percent of the nonwoven fabric sheet cross sectional area.
- 7. The nonwoven fabric sheet of claim 1 wherein the strands at the bond sites are oriented by less than 100 percent.
- 8. The nonwoven fabric sheet of claim 7 wherein strands at the bond sites are oriented by less than 5 percent.
- 9. The nonwoven fabric sheet according to claim 1 having regions with oriented strand and adjacent regions without oriented strands.
- 10. The nonwoven fabric sheet according to claim 1 wherein the strand length between the bond sites is greater than the length of the flexible nonwoven material between the bond sites creating upstanding strand loop portions.
- 11. The nonwoven fabric sheet according to claim 8 wherein said strands have a greater width between said opposite elongate side surface portions at said first sheet bond sites.
- 12. The nonwoven fabric sheet according to claim 1 wherein the strands and at least some of the fibers forming the flexible nonwoven material are formed of a polyolefin.
- 13. A disposable diaper or other garment including a nonwoven fabric sheet, the nonwoven fabric sheet comprising:a multiplicity of generally parallel elongate strands of inelastic thermoplastic material extending in spaced relationship, each of said strands having opposite elongate side surface portions that are spaced from and are adjacent elongate side surface portions of adjacent strands, and each of said strands also having corresponding opposite first and second elongate surface portions extending between said opposite elongate side surface portions; and a first sheet of flexible nonwoven material having anchor portions thermally bonded at first sheet bond sites of the strands along said first elongate surface portions wherein thermoplastic material forming the elongate strands is oriented at least between adjacent bond sites along the length of the strands.
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Name |
Date |
Kind |
4931355 |
Radwanski et al. |
Jun 1990 |
A |
5681302 |
Melbye et al. |
Oct 1997 |
A |
5705249 |
Takai et al. |
Jan 1998 |
A |
6096016 |
Tsuji et al. |
Aug 2000 |
A |
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Number |
Date |
Country |
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EP |
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EP |