U.S. patent application number 09/738606 was filed with the patent office on 2001-04-26 for hook fasteners and methods of manufacture.
This patent application is currently assigned to Velcro Industries B.V. Netherlands corporation. Invention is credited to Condon, Mark J., Leak, A. Todd, Provost, George A., Roslansky, Apiromraj S., Serbiak, Paul J..
Application Number | 20010000365 09/738606 |
Document ID | / |
Family ID | 24937898 |
Filed Date | 2001-04-26 |
United States Patent
Application |
20010000365 |
Kind Code |
A1 |
Provost, George A. ; et
al. |
April 26, 2001 |
Hook fasteners and methods of manufacture
Abstract
A hook fastener member having rows of molded hook-shaped
fastener elements that lie in planes aligned with the rows, with
generally planar plate portions at the outermost ends of at least
some of the fastener elements, the plate portions lying generally
parallel to the base of the fastener member. The plate portions can
enhance engagement of the hook fastener members with mating loop
fastener members, particularly with low loft non-woven loop
fastener members. A method of making fastener members is provided.
Molten resin is extruded and applied to a molding roller, creating
preforms. The outermost portions of at least some of the preforms
are flattened, thereby forming generally plate shaped portions.
Disposable absorbent garments advantageously incorporate the hook
fastener members.
Inventors: |
Provost, George A.;
(Litchfield, NH) ; Condon, Mark J.; (Melrose,
MA) ; Leak, A. Todd; (Neenah, WI) ; Roslansky,
Apiromraj S.; (Little Chute, WI) ; Serbiak, Paul
J.; (Appleton, WI) |
Correspondence
Address: |
DANIEL J. SEPANIK
Fish & Richardson P.C.
225 Franklin Street
Boston
MA
02110-2804
US
|
Assignee: |
Velcro Industries B.V. Netherlands
corporation
|
Family ID: |
24937898 |
Appl. No.: |
09/738606 |
Filed: |
December 15, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09738606 |
Dec 15, 2000 |
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08988414 |
Dec 10, 1997 |
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08988414 |
Dec 10, 1997 |
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08731061 |
Oct 9, 1996 |
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5953797 |
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Current U.S.
Class: |
24/452 ; 264/167;
264/280 |
Current CPC
Class: |
Y10T 24/33 20150115;
Y10T 24/2742 20150115; Y10T 24/2792 20150115; Y10T 24/2725
20150115; A44B 18/0049 20130101; B29C 2043/461 20130101; B29C 43/46
20130101; A44B 18/0061 20130101; B29C 43/222 20130101; Y10T 24/2767
20150115; Y10T 24/27 20150115; A61F 13/5633 20130101; B29L 2031/729
20130101; B29C 2043/465 20130101 |
Class at
Publication: |
24/452 ; 264/167;
264/280 |
International
Class: |
B29C 047/00; A44B
001/04; A44B 011/25 |
Claims
What is claimed is:
1. A fastener member comprising a base, and multiple rows of molded
hook-form fastener elements extending from said base and exposed
for engagement with a fabric, each said hook-form fastener element
comprising a stem portion joined at one end to said base and at
least one fiber-engaging hook-form portion joined at the opposite
end of said stem portion and having a free end, said hook-form
fastener elements lying substantially only in planes aligned with
respective rows, at least some of said fastener elements including
a fiber-engaging plate portion at the outermost portion of said
hook-form portion, said plate portion lying generally parallel to
said base, said plate portion providing an overhang portion in the
direction perpendicular to its row.
2. The fastener member of claim 1 wherein said plate portion has a
thickness, in the direction normal to said base, that is less than
the height, in the direction normal to said base, of the free end
of said hook portion.
3. The fastener member of claim 1 wherein said fastener elements
are formed of thermoplastic resin, said stem portions of said
elements being molded integrally with said base, and said plate
portion comprising a post-formed structure formed from the resin of
said uppermost portion of said molded fastener element.
4. The fastener member of claim 1 wherein substantially all the
hook-form portions of the fastener elements in a first row extend
in one direction along said row and substantially all the hook-form
portions of the fastener elements in a neighboring second row
extend in the opposite direction.
5. The fastener member of claim 4 in which substantially all of the
fastener elements in said first row include a said plate portion,
and substantially all of the fastener elements in said neighboring
second row do not include a said plate portion.
6. The fastener member of claim 1 wherein said stem portion has
substantially flat relatively broad sides, a cross-section of each
said stem portion, taken parallel to said base at the mid-height
region of the stem, having a width in the direction of said row and
a thickness in the direction perpendicular to said row, said width
being about twice said thickness or more.
7. The fastener member of claim 6 wherein the width of said stem
tapers from said base to said hook-form portion.
8. The fastener member of claim 1 wherein a central axis of said
stem is inclined, in the direction of the respective row, at a
substantially acute angle relative to said base.
9. The fastener member of claim 1 in which substantially all of
said fastener elements include said plate portions.
10. A fastener member comprising a base, and multiple rows of
molded fastener elements extending from said base, each said
fastener element comprising a stem portion joined at one end to
said base, said stem being inclined at a substantially acute angle
relative to the base, in the direction of the respective row of
said fastener element and lying substantially only in planes
aligned with its respective row, and fiber-engaging plate portions
disposed at the opposite, outermost end of the stem portions of at
least some of the tallest of said fastener elements, said plate
portions extending transversely to the direction of the respective
row to form overhang portions.
11. The fastener member of claim 10 in which substantially all of
said fastener elements include said plate portions.
12. The fastener member of claim 10 wherein a cross-section of each
said stem portion, taken parallel to said base, has a width in the
direction of said row and a thickness in the direction
perpendicular to said row, said width being substantially greater
than said thickness.
13. A closure comprising the fastener member of claim 6 or claim 12
and a non-woven fabric engaged therewith, the base of said fastener
and said non-woven fabric being under tension in opposite
directions such that said fastener elements are subjected to and
resist shear forces caused by said tension loading, the tension
acting in the direction of the thickness of said stem portion.
14. A method for making fastener members comprising: extruding
molten resin and applying said resin to a molding roller having
forming cavities around its perimeter; applying pressure to said
resin to cause said resin to fill said cavities, thereby forming a
fastener member preform, said fastener member preform comprising a
base and a multiplicity of discrete fastener element preforms
aligned in at least one row, integrally molded with and extending
from said base at a substantially acute angle, said fastener
element preforms comprising stem portions with outermost ends lying
over said base substantially only in planes aligned with its row;
stripping said fastener member preforms from said molding roller;
and flattening said outermost portions of at least some of said
fastener element preforms, thereby forming generally plate-shaped
portions disposed at said outermost ends and generally parallel to
said base and perpendicular to the row.
15. The method of claim 14 wherein said flattening comprises
heating said outermost ends of at least some of said fastener
element preforms to a temperature that is near the melt temperature
of said resin and applying pressure to said outermost ends.
16. The method of claim 15 wherein said heating and said applying
pressure are performed in a single step.
17. The method of claim 16 wherein said single step comprises
passing said fastener member preforms by a heated roller and
pressing at least some of said fastener element preforms against
said heated roller.
18. The method of claim 14 wherein said fastener member preforms
are formed and said outermost ends of at least some of said
preforms are flattened as part of a single, continuous process.
19. The method of claim 14 wherein said outermost ends of at least
some of said fastener element preforms are flattened in a
post-processing operation.
20. The method of claim 14 further comprising, prior to said
flattening, correcting differences in the heights of said fastener
element preforms to ensure generally uniform height.
21. The method of claim 20 wherein said correcting comprises
pressing a knock-down roller against said outermost ends of said
fastener element preforms.
22. A method for making fastener members comprising: extruding
molten resin and applying said resin to a molding roller having
forming cavities around its perimeter; applying pressure to said
resin to cause said resin to fill said cavities, thereby forming a
fastener member preform, said fastener member preform comprising a
base and a multiplicity of discrete fastener element preforms
aligned in at least one row, integrally molded with and extending
from said base at a substantially acute angle, said fastener
element preforms comprising stem portions with outermost ends lying
over said base substantially only in planes aligned with its row,
the outermost portions of some fastener elements being farther away
from the base, as formed, than the outermost portions of at least
some of other fastener elements; stripping said fastener member
preforms from said molding roller; and flattening at least some of
said outermost portions farthest away from said base, thereby
forming generally plate-shaped portions disposed at said outermost
ends and generally parallel to said base and perpendicular to the
row.
23. The preforms method of claim 22 in which stripping said
fastener member from said molding roller causes the fastener
members extending in one direction to be deformed to be of greater
height than fastener members extending in another direction.
24. The method of claim 14 which comprises flattening said
outermost portion of substantially all of said fastener element
preforms.
25. The product formed by the method of claim 11 or claim 24.
26. A method of improving the engageability of a hook-type fastener
member with a non-woven loop-type fastener member, said hook-type
fastening member comprising a base and a multiplicity of generally
hook-shaped fastener elements integrally molded with and extending
from said base in a given direction or in that direction and the
opposite direction, and lying only in planes parallel with the
given direction and perpendicular to the base, said method
comprising flattening outermost ends of at least some of said
fastener elements to form generally plate-form portions disposed at
said distal ends and generally parallel to said base and
perpendicular to the planes.
27. A disposable absorbent garment having first and second opposed
longitudinal end portions, said garment comprising: an outer cover;
a body-side liner; an absorbent core located between said outer
cover and said body-side liner; a loop member operably associated
with said garment; and a fastener member operably associated with
said garment for separable engagement with said loop member, said
fastener member comprising: a base; and multiple rows of molded
hook-form fastener elements extending from said base and exposed
for engagement with said loop member, each said hook-form fastener
element comprising a stem portion joined at one end to said base
and least: one fiber-engaging hook-form portion joined at the
opposite end of said stem portion and having a free end, said
hook-form fastener elements lying substantially only in planes
aligned with respective rows, at least some of said fastener
elements including a fiber-engaging plate portion at the outer most
portion of said hook-form portion, said plate portion lying
generally parallel to said base, said plate portion providing an
overhang portion in the direction perpendicular to its row.
28. The garment of claim 27 wherein said plate portion has a
thickness, in the direction normal to said base, that is less than
the height, in the direction normal to said base, of the free end
of said hook portion.
29. The garment of claim 27 wherein said stem portion has
substantially flat relatively broad sides, a cross-section of each
said stem portion, taken parallel to said base at the mid-height
region of the stem, having a width in the direction of said row and
a thickness in the direction perpendicular to said row, said width
being about twice said thickness or more.
30. The garment of claim 27 wherein said loop member comprises a
nonwoven material.
31. The garment of claim 27 wherein said loop member is joined to
the outer cover in said first opposed longitudinal end section and
said fastener member is operably associated with said second
opposed longitudinal end section.
32. The garment of claim 31 having a longitudinal axis wherein the
fastener elements are oriented parallel to the longitudinal axis of
the garment.
33. A disposable absorbent garment having first and second opposed
longitudinal end portions, said garment comprising: an outer cover;
a body-side liner; an absorbent core located between said outer
cover and said body-side liner; a loop member operably associated
with said garment; and a fastener member operably associated with
said garment for separable engagement with said loop member, said
fastener member comprising: a base; and multiple rows of molded
fastener elements extending from said base, each said fastener
element comprising a stem portion joined at one end to said base,
said stem being inclined at a substantially acute angle relative to
the base, in the direction of the respective row of said fastener
element and lying substantially only in planes aligned with its
respective row, and fiber-engaging plate portions disposed at the
opposite, outermost end of the stem portions of at least some of
said plate portions extending transversely to the direction of the
respective row to form overhang portions.
34. The garment of claim 33 wherein a cross-section of each said
stem portion, taken parallel to said base, has a width in the
direction of said row and a thickness in the direction
perpendicular to said row, said width being substantially greater
than said thickness.
35. The garment of claim 33 wherein said loop member comprises a
nonwoven material.
36. The garment of claim 33 wherein said loop member is joined to
the outer cover in said first opposed longitudinal end section and
said fastener member is operably associated with said second
opposed longitudinal end section.
37. The garment of claim 33 having a longitudinal axis wherein the
fastener elements are oriented parallel to the longitudinal axis of
the garment.
38. The garment of claim 27 or claim 33 in which substantially all
of said fastener elements include said plate portions.
Description
BACKGROUND OF THE INVENTION
1. The invention relates to improved hook members for hook-and-loop
fastening and methods of manufacturing hook members.
2. In general, hook-and-loop fasteners comprise two mating
components: a hook member that has upstanding, hook-type fastener
elements, and a loop member that has a surface that provides fibers
or fiber loops with which the hook elements become engaged.
3. As used here, a "hook member" means a member having fastener
elements whose hooks extend substantially in a given plane. When of
molded form, the stems of these elements are significantly broader
in the direction of their plane of extent than in the thickness
direction at a right angle thereto.
4. Hook fasteners are often preferred over other types of
fasteners, for instance, those having mushroom-like form, because
hook fasteners can provide more secure engagement with the loops,
offer advantages in manufacturing, etc.
5. Loop members for hook-and-loop fastening have been comprised of
knitted, woven, and non-woven textiles. A common example of a
non-woven textile is known by the term "spun bonded." It is made by
spinning fine filaments of plastic resin, e.g., polypropylene, and
distributing them in superposed layers. The fibers are bonded to
each other in random orientations, with a fine, low-lying, nappy
layer of looped and arched fibers exposed at the surface of the
fabric.
6. Because non-woven fabrics are inexpensive, they are desired for
use as the loop part of fasteners for low cost items, particularly
disposable products such as diapers, surgical gowns, and sanitary
napkins. It is desirable to provide fastener members useful with
very low cost, low loft non-wovens and other low loft fabrics.
SUMMARY OF THE INVENTION
7. One aspect of the invention relates to a fastener member useful
for separable engagement with surface fibers of a low-loft,
non-woven fabric or the like. The fastener includes a base and
multiple rows of molded hook-form fastener elements extending from
the base and exposed for engagement with the fabric. Each of the
hook form fastener elements comprises a stem portion joined at one
end to the base and at least one fiber-engaging hook-form portion
joined at the opposite end of the stem portion and having a free
end. The hook-form fastener elements lying substantially only in
planes aligned with respective rows. At least some of the fastener
elements include a fiber-engaging plate portion at the outermost
portion of the hook-form portion, which plate portion lies
generally parallel to the base. The plate portion provides an
overhanging portion in the direction perpendicular to its row that
can engage the surface fibers of the fabric.
8. Certain implementations of this aspect of the invention include
one or more of the following features. The fastener member, in
certain implementations, provides: a plate portion which has a
thickness, in the direction normal to the base, that is less than
the height, in the direction normal to the base, of the free end of
the hook portion; fastener elements formed of thermoplastic resin,
the stem portions of the elements being molded integrally with the
base, and the plate portion comprising a post-formed structure
formed from the resin of the uppermost portion of the molded
fastener element; that substantially all the hook-form portions of
the fastener elements in a first row extend in one direction along
the row and substantially all the hook-form portions of the
fastener elements in a neighboring second row extend in the
opposite direction; that substantially all of the fastener elements
include plate portions; that substantially all of the fastener
elements in the first row contain a plate portion while
substantially all of the elements in the neighboring second row do
not; a stem portion which has substantially flat relatively broad
sides, a cross-section of each stem portion, taken parallel to the
base at the mid-height region of the stem, having a width in the
direction of the row and a thickness in the direction perpendicular
to the row, the width being about twice the thickness or more; a
stem in which the width of the stem tapers from the base to the
hook-form portion; a central axis of the stem is inclined, in the
direction of the respective row, at a substantially acute angle
relative to the base.
9. Another aspect of the invention relates to a fastener member
useful for separable engagement with surface fibers of a low-loft,
non-woven fabric or the like. The fastener comprises a base and
multiple rows of molded fastener elements extending from the base.
Each fastener element comprises a stem portion joined at one end to
the base, the stem being inclined, at a substantially acute angle
relative to the base in the direction of the respective row of the
element, and lying substantially only in planes aligned with its
respective row relative to the base, and a fiber-engaging plate
portion disposed at the opposite, outermost end of the stem
portion, the plate portion extending transversely to the direction
of the respective row to form an overhang portion that can engage
the surface fibers of the fabric.
10. Certain implementations of this aspect of the invention include
one or more of the following features. The fastener member, in
certain implementations, provides a cross-section of each stem
portion, taken parallel to the base, has a width in the direction
of the row and a thickness in the direction perpendicular to the
row, the width being substantially greater than the thickness; that
substantially all of the fastener elements include plate
portions.
11. In accord with another implementation of the invention, a
closure is provided comprising a fastener member as described above
and a non-woven fabric engaged therewith, the base of the fastener
and the non-woven fabric being under tension in opposite directions
such that the fastener elements are subjected to and resist shear
forces caused by the tension loading, the tension acting in the
direction of the thickness of the stem portion.
12. Another aspect of the invention relates to a method for making
fastener members comprising extruding molten resin and applying the
resin to a molding roller having forming cavities around its
perimeter. Pressure is applied to the resin to cause the resin to
fill the cavities, thereby forming a fastener member preform, the
fastener member preform comprising a base and a multiplicity of
discrete fastener element preforms integrally molded with and
extending from the base at a substantially acute angle, the
fastener element preforms aligned in at least one row comprising
stem portions with outermost ends lying over the base substantially
only in planes aligned with its row. Fastener member preforms are
stripped from the molding roller. The outermost portions of at
least some of the fastener element preforms are flattened, thereby
forming generally plate-shaped portions disposed at the outermost
ends and generalize parallel to the base and perpendicular to the
row.
13. Certain implementations of this aspect of the invention include
one or more of the following features. The method, in certain
implementations, provides: the flattening comprises heating the
outermost ends of at least some of the fastener element preforms to
a temperature that is near the melt temperature of the resin and
applying pressure to the outermost ends; the heating and the
applying pressure are performed in a single step; the single step
comprises passing the fastener member preforms by a heated roller
and pressing at least some of the fastener element preforms against
the heated roller; the fastener member preforms are formed and the
outermost ends of at least some of the preforms are flattened as
part of a single, continuous process; the outermost ends of at
least some of the fastener element preforms are flattened in a
post-processing operation; prior to the flattening, differences in
the heights of the fastener element preforms are corrected to
ensure generally uniform height; the correcting comprises pressing
a knock-down roller against the outermost ends or the fastener
element preforms; that substantially all of the fastener elements
are flattened; that a product is formed by the method.
14. In another aspect of the invention, the outermost portions of
some fastener elements are farther away from the base, as formed,
than the outermost portion of at least some other fastener
elements. At least some of the outermost portions farthest away
from the base are then flattened, forming generally plate-shaped
portions disposed at said outermost ends and generally parallel to
the base and perpendicular to the row.
15. In a preferred embodiment, stripping the preforms from the
molding roller causes the fastener members extending in one
direction to be deformed to be of greater height than fastener
members in another direction.
16. Another aspect of the invention relates to a method for
improving the engageability of a hook-type fastener member with a
non-woven loop-type fastener member. The hook-type fastening member
comprising a base and a multiplicity of generally hook-shaped
fastener elements integrally molded with and extending from the
base in a given direction or in that direction and the opposite
direction and lying only in planes parallel with the given
direction and perpendicular to the base. The method comprises
flattening outermost ends of at least some of the fastener elements
to form generally plate-form portions disposed at the distal ends
and generally parallel to the base and perpendicular to the
planes.
17. The new hook fastener members are well suited for engagement
with low loft non-woven loop members since the outer plate portions
of the fastener elements that overhang the sides of the elements
are able to slide under and initially engage the surface fibers of
the loop member. This feature can improve the level of engagement
of the fastener, especially when the fastener elements are
subjected to shear forces acting sideways relative to the direction
of the plane of the hook elements. The flat-top hook fastener
elements, while providing the secure engagement by the hooks, also
can avoid skin irritation since the area of contact between the
skin and the fastener elements is relatively large. This is of
particular value when a hook fastener comes in contact with the
skin of babies. Finally, these hook fasteners can be manufactured
using conventional hook-member tooling with simple additional
post-molding steps.
18. Other aspects of the invention concern a disposable absorbent
garment having first and second opposed longitudinal end portions,
and comprises an outer cover; a body-side liner; an absorbent core
located between the outer cover and the body-side liner; a loop
member operably associated with the garment; and a fastener member
operably associated with the garment for separable engagement with
the loop member, the fastener member comprising: a base; and
multiple rows of molded hook-form fastener elements extending from
the base.
19. According to one aspect of the invention, the fastener elements
are exposed for engagement with the loop member, each of the
hook-form fastener elements comprising a stem portion joined at one
end to the base and at least one fiber-engaging hook-form portion
joined at the opposite end of the stem portion and having a free
end, the hook-form fastener elements lying substantially only in
planes aligned with respective rows. At least some of the fastener
elements include a fiber-engaging plate portion at the outer most
portion of the hook-form portion, the plate portion lying generally
parallel to the base, the plate portion providing an overhang
portion in the direction perpendicular to its row.
20. Certain implementations of this aspect of the invention have
one or more of the following features.
21. The plate portion has a thickness, in the direction normal to
the base, that is less than the height, in the direction normal to
the base, of the free end of the hook portion. The stem portion has
substantially flat relatively broad sides, a cross-section of each
stem portion, taken parallel to the base at the mid-height region
of the stem, having a width in the direction of the row, and a
thickness in the direction perpendicular to the row, the width
being about twice the thickness or more.
22. Certain advantageous implementations of this aspect of the
invention have one or more of the following features. The loop
member comprises a nonwoven material. The loop member is joined to
the outer cover in the first opposed longitudinal end section and
the fastener member is operably associated with the second opposed
longitudinal end section, preferably the garment 25 having a
longitudinal axis and wherein the fastener elements are oriented
parallel to the longitudinal axis of the garment.
23. According to another aspect of the invention concerning the
disposable absorbent garment, each of the fastener elements
comprise a stem portion joined at one end to the base, the stem
being inclined at a substantially acute angle relative to the base,
in the direction of the respective row of the fastener element and
lying substantially only in planes aligned with its respective row.
At least some of the elements also comprise a fiber-engaging plate
portion disposed at the opposite, outermost end of the stem
portion, the plate portion extending transversely to the direction
of the respective row to form an overhang portion.
24. In preferred embodiments of the aspect of the invention, a
cross-section of each stem portion, taken parallel to the base, has
a width in the direction of the row and a thickness in the
direction perpendicular to the row, the width being substantially
greater than the thickness.
25. Certain advantageous implementation of both of these aspects of
the invention include that substantially all of the fastener
elements include plate portions.
BRIEF DESCRIPTION OF THE DRAWINGS
26. FIGS. 1 and 2 are side elevational and plan views,
respectively, showing one embodiment of a hook fastener member.
27. FIGS. 1a, 1b, and 1c are detailed side elevational, end, and
plan views, respectively, showing a single fastener element of the
fastener member in FIG. 1.
28. FIG. 3 is a schematic representation of an assembly line in
which fastener members as shown in FIGS. 1 and 2 are applied to
diapers; FIG. 3a is a blow-up of a portion of FIG. 3 showing the
orientation of the fastener elements on the diaper; and FIG. 4
illustrates the direction of stress applied to the fastener
elements during normal use.
29. FIG. 5 is a schematic "peer-through window" view illustrating
the engagement of a hook fastener element with a non-woven loop
member while FIGS. 5a, 5b, and FIG. 5c are sequential diagrams
illustrating the engagement of a hook fastener element with a loop
of a non-woven fabric.
30. FIG. 6 is a schematic representation of the manufacturing
process used to make hook fastener members.
31. FIGS. 6a, 6b, and 6c are side elevational views showing
fastener element preforms used to make hook fastener members.
32. FIGS. 7 and 8 are side elevational and plan views,
respectively, showing a second embodiment of a hook fastener
member.
33. FIG. 7a is a detailed side elevational view showing a fastener
element of the fastener member of FIG. 7.
34. FIGS. 9 and 10 are side elevational and plan views,
respectively, showing a third embodiment of a hook fastener
member.
35. FIG. 9a is a detailed side elevational view showing a fastener
element of the fastener member of FIG. 10.
36. FIGS. 11 and 12 are side elevational and plan views,
respectively, of a fourth embodiment of a hook fastener member.
EMBODIMENTS
37. A preferred embodiment 110 of a hook fastener member,
particularly useful on disposable diapers, is shown in FIGS. 1, 1a,
1b, 1c, and 2. The hook fastener member consists of a base sheet
112 and multiple parallel rows of integrally molded hook-form
fastener elements 114 extending from the base sheet. Although only
three rows are shown in several of the figures, it is to be
understood that the fastener member may comprise several rows.
38. As shown in greater detail in FIGS. 1a-1c, each fastener
element of FIG. 1 has a stem portion 116 of uniform thickness that
has flat vertical sides 116a, 116b that extend normal to the plane
of the base sheet 112. Joined to the upper end of the stem is a
re-entrant, hook-form portion that engages loops or fibers. At the
top of the fastener is joined a thin, generally disk-shaped outer
plate portion 118 oriented substantially parallel to the base
sheet.
39. The re-entrant hook-form portion curves over and down toward
the base sheet from the upper end of the stem portion 116 to define
a fiber-retaining recess 119 on the underside of the hook-form
portion.
40. The stem portion in side elevation, as seen in FIG. 1a, tapers
outwardly from a wide base to a relatively narrow outer portion in
the region of the recess 119. The fastener elements are generally
aligned in multiple rows parallel with the flat sides of the
individual elements, and the outer plate portion of each fastener
element has portions that extend transversely, to overhang the
sides 116a, 116b of the fastener element (FIGS. 1b, 1c, 2).
41. In this preferred embodiment, the edge surfaces 123, 125 of the
stem portion form angles .theta..sub.1 and .theta..sub.2 relative
to the base sheet, respectively, that are substantially greater
than ninety degrees. Preferably, .theta..sub.1 and .theta..sub.2
are between about 30 and 160 degrees. More preferably, they are
each about 115 degrees and 125 degrees, respectively. Forming the
stem portion such that the edges are straight or slant inward
allows the preform to be removed more easily from the molding
roller 50 because the hook-form portion 117 can pass more easily
through the portion of the molding roller in which the stem portion
was formed.
42. For use in an important application for the new fastener, in
conjunction with non-woven loop members, the fastener elements are
generally quite small. Hence, height 130 of the fastener element
114 is preferably between about 0.005 inch and about 0.030 inch,
with about 0.0150 inch being most preferred. Furthermore, the base
width 126--i.e., the width of the stem portion, taken parallel to
the base sheet 112 at the level where the stem portion joins the
base sheet, disregarding the fillets 128a and 128b--is preferably
between about 0.010 inch and about 0.025 inch, with about 0.0170
inch being most preferred.
43. Furthermore, the fastener elements are provided in relatively
high density, for example, from about 500 to about 4,000,
alternatively from about 1,000 to 2,500, alternatively from about
1,500 to about 2,000 fastener elements per square inch. For
example, as shown in FIG. 2, the elements preferably are spaced
apart laterally a distance 135 of about 0.008 inch, and the stem
portions 116 preferably have a thickness 136 of about 0.006 lineal
inch. This yields a widthwise density of approximately 71 fastener
elements per inch. In the lengthwise direction, there are
preferably about 24 fastener elements per lineal inch. Hence, there
are preferably on the order of 1700 fastener elements per square
inch in this preferred embodiment.
44. A distinctive feature of the hook-form fastener element 114 is
the presence of the plate portion 118. This feature contributes to
making the hook fastener embodiment 110 particularly useful for
engaging the loops of non-woven fabrics in general and, in
particular, the low-loft non-woven fibers desired to be used on
disposable diapers.
45. As shown in FIGS. 3 and 3a, disposable diapers 10 commonly are
made on an assembly line with the fastener tabs 12 extending to the
sides, perpendicular to the direction in which the diapers travel.
The hook fastener member is provided in large rolls 14 of hook
fastener tapes. As explained below, the hook fastener tapes are
made using a rotating molding roll in which the hook elements are
aligned with the circumference of the roll. As a result of that
process, the hook-form fastener elements are aligned along the
lengthwise direction of the fastener tapes. For manufacturing
efficiency, the hook fastener tapes may be unwound and fed out
running parallel to the line of diapers. As each diaper passes the
appropriate station, a bonding apparatus 16 such as an ultrasonic
welder attaches a patch 18 of hook fastener material to each of the
fastener tabs 12. As a result, the hook fastener elements are
oriented parallel to the longitudinal axis 20 of the diapers, as
shown in greater detail in FIG. 3a. Alternatively, the fastener
tabs 12 having hook fastener material 18 attached thereto may be
formed in a separate process and the fastener tab attached to the
diaper during the diaper manufacturing process. Such a separate
process is described, for example, in PCT Application Publication
No. WO95/05140 which is hereby incorporated by reference.
46. When the diaper is put on a baby, it will have the
configuration and orientation shown in FIG. 4. Hence, when the
fastener tabs 12 are engaged with the mating non-woven loop member
strip 22, the tensile forces S applied to the base of the fastener
member and the loop member will act perpendicular to the
orientation of the hook-form fastener elements, thereby subjecting
the closure to lateral shear forces, as suggested in FIG. 5.
47. During fastening the fastener tabs 12 will slide slightly
relative to the loop member strip 22. This is indicated
schematically in FIG. 5, which, with exaggeration for purposes of
illustration, shows the edge of the fastener tab 12 at three
successive locations 5a, 5b, and 5c. In FIG. 5 there is a
"peer-through window" depiction of a single fastener element 114
surrounded by the surface fibers 23 of the non-woven loop member
22, as seen from below the fastener element. As depicted in FIGS.
5a, 5b, and 5c, which correspond in FIG. 5 to the locations 5a, 5b,
and 5c, respectively, as the fastener element slides slightly, it
is shown to intercept a surface fiber 23 which is depicted as
anchored to member 12. During the initial sliding action, an
overhanging portion of the thin outer plate 118 of the fastener
element slides under the low-lying surface fiber 23 (FIG. 5b), as
an initial part of the engaging action. As relative motion
continues, the fiber is guided by the fillets 120 between the plate
portion 118 and the hook-form portion 117 and the stem portion (see
FIG. 1b). The fiber 23 is thus guided under the hook-form portion
117 and is secured in the re-entrant fiber-retaining recess 119 to
more securely engage the fastener member with the fiber.
48. In FIG. 5b, the end of the hook element is shown to have been
deflected sideways by the force of engagement with the loop member
(shown exaggerated for purposes of illustration). This bending,
facilitated by the relative thinness (dimension 136) of the element
and the off-center loading on the head of the fastener element is
seen to contribute to the effectiveness of the engaging action.
49. As shown in FIG. 6, a preferred method for making such flat-top
hook fastener members entails extruding molten resin into the nip
formed between a cooled molding roller 50 and a pressure-applying
roller 52, as taught by Fischer, U.S. Pat. No. 4,794,028, fully
incorporated herein by reference. The cooled molding roller has
cavities about its periphery that are configured to produce
fastener element preforms 154, which are shown in greater detail in
FIG. 6a.
50. Because the fastener element preforms face in opposite
directions, the fastener element preforms in half the columns are
oriented along the direction of travel of the tape, and the
fastener element preforms in the other half of the columns are
oriented opposite to the direction of travel of the tape. The
fastener element preforms that are oriented against the direction
of travel can leave the mold cavities of the moving roll without
significant bending, but the fastener element preforms that are
oriented along the direction of travel are bent around the edges of
the mold cavities as they are extracted from the cavities. This
deforms them slightly, causing them to extend higher from the base
sheet and at a slightly steeper angle than the preforms that are
oriented along the direction of travel.
51. For making the two sets of preforms more uniform, the preforms
are passed under a knock-down roller 56, the spacing of which,
relative to wrap-around roller 57, is adjustable. The knock-down
roller pushes the higher and steeper preforms back to the same
level, relative to the base sheet, as the level of the preforms
that are oriented with the direction of travel of the tape. This
leveling will permit more uniform formation of the plate portions
118, discussed below. The knock-down roller 56 is located close to
the position where the preforms are withdrawn from the cavities so
that the preforms are still slightly soft and permanently
deformable when they pass under the knock-down roller and thus
retain their new shape.
52. Alternatively, to form the plate portion on only some of the
fastening elements preforms, the knock down roller 56 can be
removed. In this manner, the elements oriented against the
direction of travel are left in an elongated, higher state and may
be deformed to form plate portions 118 without forming plate
portions on the elements oriented along the direction of
travel.
53. After the preforms have cooled sufficiently to be strong enough
to withstand pressure applied to them without being deformed, the
thin, outer plate portions 118 are formed, as at station 58. The
plate portions can be formed either in line with the molding
process, i.e., as part of a continuous operation, or they can be
formed in a separate, post-forming operation at some later time.
Hence, the fastener tape is shown as broken in FIG. 6 to indicate
this variability.
54. To form the outer plate portions, the tape of fastener element
preforms is passed through gap 60 between a thermo-forming heated
roller 62 and a support roller 64, the gap width of which is
adjustable. Roller 62 is heated to a selected temperature
sufficient to thermally reform the elements. Thus, as the preforms
come into contact with the heated thermo-forming roller 62, their
outer ends 155 (FIG. 6a) are thermo-formed by the action of the
rollers to provide the disk-shaped plate portions 118 of the
fastener elements 114.
55. The selected temperature of roller 62 depends upon the thermal
properties of the particular resin being used to make the fastener
member and the selected speed of operation. Presently, the shell
material of disposable diapers is often polypropylene. In certain
applications, nylon or other materials would also be appropriate.
To ensure good bonding when the hook fastener members are attached
to the fastener tabs of the diapers 12, the hook fastener member is
also preferably made from polypropylene. In this case, the roller
62 is heated to a surface temperature of approximately 350.degree.
Fahrenheit, and has operated in a demonstration line at lineal
speed of approximately 11 feet per minute (Much higher speeds will
be used in production.). The preforms approach the roller 62 nearly
tangentially. This results in a temperature at the hook surface
which is approximately the same as the melt temperature of the
polypropylene resin, and causes the end of the preform to be
softened to the point of being permanently deformable under
pressure, without being caused to melt to a highly fluid state.
56. It is, of course, foreseeable that other plastics will be used
to form such flat-top hook fastener members. The material selected
preferably has a relatively low melt flow index, which is a measure
of the viscosity of the resin when it is molten. Resins with
fractional melt flow indices, i.e., indices that are less than 1.0,
are most preferred, although under certain circumstances and hook
designs, resins which melt flow indices as high as 5.0 or 10.0, or
even higher, can be used by careful balancing of the steps of the
process. The temperature of the roller 62 and the lineal speed
through the station 58 are selected to impart a temperature to the
hook surface which renders the selected resin moldable. For
polypropylene, as noted above, it was found that 350.degree.
Fahrenheit was appropriate. Further, additional support rollers and
the like may be employed to increase the arc of the roller 62 which
the preforms contact, thereby increasing the heating time for a
given lineal speed.
57. The width of the gap 60 between thermo-forming roller and
support roller 64 is adjusted to obtain the appropriate height 130
(FIG. 1a) of the final fastener elements, the height 130 in turn
being a function of the height of the fastener element preforms.
With regard to the amount by which the tops of the hook elements
are thermoformed, and therefore with regard to the height 30, it is
important that the outer ends not be deformed so much as to impair
the geometry of hook-form portion 117 or the ability of the
fastener element to engage and retain the fibers of the loop
member.
58. In general, the tops of the elements are thermoformed by an
amount to produce an effective overhang of the plate portion, i.e.,
the amount by which the plate portion extends beyond (overhangs)
either side 116a, 116b of the stem portion of the fastener element.
Depending upon the conditions of use, it is advantageous for the
amount of overhang to fall within the range of 5 to 50% of the
thickness of the hook element; in other conditions with the range
of 10 to 30%; and in other conditions, within the range of 15 to
25%. In certain preferred instances, the overhang is about 25% of
the thickness of the stem portion. Thus, in preferred cases the
widthwise dimension 138 of the plate portions (FIG. 2) is
approximately 1.5 to 2.0 times the thickness 136 of the stem
portion and the vertical thickness 139 of the plate portion 118 is
between about 0.2 and 0.4 times the thickness 136 of the stem
portion. The lengthwise dimension of the plate portion, in general,
will be somewhat longer than the widthwise dimension, and it is
generally allowed to be whatever dimension results from
thermoforming the plate portion sufficiently to obtain the desired
effective sideways overhang and hook height. The thickness of one
plate was 0.002 inch and the overhang was 0.003-0.004 inch. A
preferred thickness range is 0.0001 to 0.005 inch, and in certain
instances a more preferred range is 0.001 to 0.004 inch.
59. Finally with regard to the manufacturing process, in order for
the plate portions 118 to be substantially parallel to the base of
the hook fastener member, it is preferred that the heated roller 62
and support roller 64 rotate at speeds such that their tangential
surface velocities substantially match the feed rate of the
fastener tape. Otherwise, the plate portions will be dragged by, or
will drag along, the heated roller and be deformed.
60. Another preferred embodiment 210 of a flat-top hook fastening
member is shown in FIGS. 7, 7a, and 8. This embodiment has a base
sheet 212 from which extend a multiplicity of discrete, flat-top
fastener elements 214. Each fastener element 214 has a canted stem
portion 216, having flat sides similar to sides 116a, 116b of FIG.
1b. These portions are integrally molded with and extend from the
base sheet. Each fastener element also has a generally planar,
disk-shaped outer plate portion 218 located at the outer end 220 of
the stem portion that overhangs the flat sides of the canted stem
and a re-entrant hook-form portion 217 depending from the outer
plate portion. The plate portion 218 extends generally parallel to
the base sheet 212.
61. As shown in greater detail in FIG. 7a, the general
configuration of the stem portion 216 of the fastener elements can
be characterized by two parameters. First, it is canted relative to
the base 212 in that the surface 222 of the stem portion on the
side on which the hook recess is formed forms an acute cant angle
.alpha. relative to the base. Preferably, cant angle .alpha. is
between about 30 degrees and about 80 degrees; more preferably,
.alpha. is between about 40 and 60 degrees, and most preferably,
.alpha. is about 45 degrees.
62. The second parameter to characterize the configuration of the
stem portion is the base width 226 which, as before, is the width
of the stem portion, taken parallel to the base sheet 212 where the
stem portion joins the base, disregarding the fillets 228a and
228b. Preferably, the base width is between about 0.010 inch and
about 0.018 inch; more preferably, the base width is about 0.014
inch.
63. Finally, other parameters that characterize the entire fastener
element 214 are the height 230 of the fastener element, as measured
from the top surface of the base sheet 212 to the top surface of
the plate portion 218, and the widthwise dimension 238 of the plate
portion. The thickness of the stem portion 236 is preferably the
same as for the first embodiment, e.g., about 0.006 inch.
Preferably, the height is between about 0.005 inch and about 0.030
inch; more preferably, the height is about 0.015 inch.
64. As shown in FIGS. 7 and 8, the fastener elements 214 are
arranged on the base sheet 212 with the fastener elements in one
column all canted in one direction and the fastener elements in the
adjacent column all canted in the opposite direction. The spacing
and density of the fastener elements is approximately the same as
the spacing and density described above with respect to the first
embodiment.
65. The embodiment of the flat-top hook fastener member of FIGS. 7
and 8 is also made by the process shown in FIG. 6. The hook
preforms 254 are configured as shown in FIG. 6b which, like the
preforms 154 shown in FIG. 6a, are generally of hook shape,
although canted relative to the base. Other profiles for a canted
hook preform 254 can also be used. See, for example, FIG. 22 of
Provost et al., U.S. Pat. No. 4,984,339, which is incorporated by
reference.
66. The canted relationship of fasteners elements of FIGS. 7 and 9
provide a longer fastener element and a greater degree of
off-center loading when subjected to conditions as depicted in FIG.
4 of the preceding embodiment. As a result, under loading
conditions depicted in FIG. 4, a greater degree of elastic
deflection of the hook end can occur that can increase the
fiber-engaging effectiveness of the hook elements.
67. A third preferred embodiment 310 of a flat-top hook fastener
member is shown in FIGS. 9, 9a, and 10. This embodiment is similar
to the second embodiment 210 discussed above, the outer plate
overhanging the flat sides of the canted stem. The primary
difference in this embodiment is that the intersection of the
canted stem and the outer plate 318 defines a fiber-engaging hook
that is not re-entrant. This enables the overhanging plate portion
318 to slide under loop members with extremely low-lying loft. The
third embodiment is also manufactured by the method shown in FIG.
6, this time using simple tapered fastener element preforms 354
without re-entrant hooks, as shown in FIG. 6c.
68. As described above, when the fastener element performs face in
opposite directions, the fastener element preforms that are
oriented along the direction of travel are bent around the edges of
the mold cavities as they are extracted. This causes these preforms
to extend higher from the base sheet and at a slightly steeper
angle than the preforms that are oriented along the direction of
travel.
69. In certain instances is desirable to form the outer plate
portions 118 on only some of the fastener element preforms. This
can be achieved, for example, by not passing the fastener element
preforms under the knock-down roller 56. Thus, since the fastener
element preforms have different heights from the base sheet,
passing the fastener element preforms through cap 60 between the
heated roller 62 and support roller 64 will form the disk-shaped
plate portions 118 on only those fastener element preforms which
extend furthest from the base sheet (those preforms that are
oriented along the direction of travel) as shown in FIGS. 11 and
12. For some applications, having some of the fastener element
preforms possess the disk-shaped plate portions 118 and others not
possess the plate portions provides for a more satisfactory balance
of fastening properties (such as a desired balance of peel and
shear properties). In other embodiments the fastener element
preforms are formed to have different heights from the base sheet
independent of their orientation during manufacture. This is
accomplished through the use of mold cavities having different
depths during formation of the preforms. With such preforms, in one
embodiment flat tops are provided only on those preforms having the
greatest height. Forming the fastener element preforms to have
different heights from the base sheet in some instance allows
greater control over the percentage of elements that are "flat
topped." It is possible to form fastener element preforms with two,
three or more different heights from the base sheet.
70. Other embodiments are within the scope of the following
claims.
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