U.S. patent application number 11/389478 was filed with the patent office on 2006-09-28 for molding touch fastener elements.
Invention is credited to Mark A. Clarner, Christopher M. Gallant, Peter Iannazzi, Ernesto S. Tachauer.
Application Number | 20060216461 11/389478 |
Document ID | / |
Family ID | 36691387 |
Filed Date | 2006-09-28 |
United States Patent
Application |
20060216461 |
Kind Code |
A1 |
Tachauer; Ernesto S. ; et
al. |
September 28, 2006 |
Molding touch fastener elements
Abstract
A product comprising a base layer and a multiplicity of
protruding hollow formations, the protruding formations unitarily
formed with and extending upward from an upper surface of the base
layer, the hollow formations and base layer formed of thermoplastic
applied under pressure against a forming surface having forming
cavities and the base layer having a back surface including
interior surfaces of the hollow formations comprising a parting
surface from which a second thermoplastic filling the hollow
formations has been peeled.
Inventors: |
Tachauer; Ernesto S.;
(Bedford, NH) ; Iannazzi; Peter; (Hampstead,
NH) ; Gallant; Christopher M.; (Nottingham, NH)
; Clarner; Mark A.; (Concord, NH) |
Correspondence
Address: |
FISH & RICHARDSON PC
P.O. BOX 1022
MINNEAPOLIS
MN
55440-1022
US
|
Family ID: |
36691387 |
Appl. No.: |
11/389478 |
Filed: |
March 23, 2006 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60664405 |
Mar 23, 2005 |
|
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|
Current U.S.
Class: |
428/99 ; 156/199;
156/221; 428/100 |
Current CPC
Class: |
B29L 2031/729 20130101;
B32B 3/26 20130101; B32B 27/08 20130101; B32B 27/18 20130101; B32B
27/06 20130101; B32B 2307/5825 20130101; B32B 2307/726 20130101;
A61F 13/8405 20130101; A44B 18/0049 20130101; B32B 3/30 20130101;
B29C 43/28 20130101; B32B 2264/101 20130101; B32B 2307/54 20130101;
Y10T 428/24017 20150115; B32B 2264/105 20130101; B32B 2432/00
20130101; B29C 43/222 20130101; B29C 43/46 20130101; Y10T 156/1043
20150115; B29C 2043/465 20130101; A44B 18/0069 20130101; A61F
13/625 20130101; B29C 2043/461 20130101; Y10T 156/1007 20150115;
B32B 2555/00 20130101; B29C 33/68 20130101; B32B 3/00 20130101;
B32B 27/32 20130101; B32B 2274/00 20130101; B32B 2437/00 20130101;
Y10T 428/24008 20150115; B32B 2307/542 20130101 |
Class at
Publication: |
428/099 ;
428/100; 156/199; 156/221 |
International
Class: |
B32B 3/06 20060101
B32B003/06 |
Claims
1. A product comprising: a base layer and a multiplicity of
protruding hollow formations, the protruding formations unitarily
formed with and extending upward from an upper surface of the base
layer, the hollow formations and base layer formed of thermoplastic
applied under pressure against a forming surface having forming
cavities and the base layer having a back surface including
interior surfaces of the hollow formations comprising a parting
surface from which a second thermoplastic filling the hollow
formations has been peeled.
2. The product of claim 1 wherein the protruding formations are
elements of fastener formations.
3. The product of claim 2 wherein the elements of fastener elements
are loop engageable formations.
4. The product of claim 3 wherein the loop engageable formations
are molded hooks.
5. The product of claim 2 wherein the elements of fastener
formations are cylindrical hollow stems.
6. The product of claim 5 wherein the protruding formations are
cylindrical hollow stems with post-formed distal ends.
7. The product of claim 1 further comprising a flowable substance
filling the hollow formations.
8. The product of claim 7 further comprising a backing layer at
least part of which forms a bond to a surface of the base layer so
that the multiplicity of protruding formations cooperate with the
backing layer to define a multiplicity of substantially enclosed
chambers containing the flowable substance.
9. The product of claim 8 wherein the bond between the base and
backing layer substantially seals individual chambers, movement of
the flowable substance out of the individually sealed chambers
through the base layer is limited by the backing layer.
10. The product of claim 8 wherein the bond between the base and
backing layers substantially seals groups of the chambers,
individual chambers within the groups of chambers remaining in
flowable substance communication with each other while movement of
the flowable substance out of the groups of chambers is limited by
the backing layer.
11. The product of claim 8 wherein at least 10 percent of the
protruding formations also defines an upper opening for dispensing
the flowable substance.
12. The product of claim 11 wherein the opening is sized such that
surface tension and viscosity substantially retain the flowable
substance within the chambers until the protruding formations
deform in response to applied pressure.
13. The product of claim 11 further comprising a sealing strip
covering the upper openings, the sealing strip removable to
dispense the flowable substance through the upper openings.
14. The product of claim 8 wherein the protruding formations each
contain a discrete area whose structural strength is weaker than
the structural strength of other areas of the protruding
element.
15. The product of claim 8 wherein the flowable substance comprises
a component that volatilizes when exposed to the atmosphere.
16. The product of claim 15 wherein the thermoplastic forming the
hollow formations is chosen from thermoplastics whose permeability
allows dispersion of the volatile component through the
thermoplastic.
17. The product of claim 15 further comprising a disposable,
absorbent undergarment wherein the base layer, hollow formations,
flowable substance, and backing layer are attached to the
disposable, absorbent undergarment.
18. The product of claim 15 further comprising a container liner
portion wherein the base layer, hollow formations, flowable
substance, and backing layer are attached to the container liner
portion.
19. The product of claim 15 further comprising a sampler portion
wherein the base layer, hollow formations, flowable substance, and
backing layer are attached to the sampler portion with a sealing
layer covering the first portion and limiting movement of the
flowable substance out of the first portion, the sealing layer
removable to dispense the flowable substance.
20. The product of claim 8 wherein the flowable substance is
selected from a group including: a medicament appropriate for
topical application; an antibiotic; an analgesic; components that
reduce transmission of ultraviolet radiation; and components that
repel insects.
21. A method of forming a sheet-form product, the method
comprising: providing a forming surface having a multiplicity of
inwardly extending forming cavities; forming a multi-layer sheet in
the interior of which is a parting surface defined by materials of
limited compatibility, material of the sheet lying on each side of
the parting surface having peelable tensile strength; pressing the
multi-layer sheet against the forming surface to cause the
multi-layer sheet to substantially conform to and fill the
cavities; and peeling the multi-layer sheet apart at the parting
surface, whereby material directly engaging the forming surface
defines a sheet-form member having a multiplicity of hollow
formations.
22. The method of claim 21 in which the forming cavities define at
least stems for fastener elements.
23. The method of claim 22 wherein the forming cavities define
cylindrical formations.
24. The method of claim 22 wherein the forming cavities define loop
engageable formations.
25. The method of claim 24 wherein the loop engageable formations
are molded hooks.
26. The method of claim 21 wherein forming a multi-layer sheet
comprises continuously introducing a first molten thermoplastic and
a second molten thermoplastic into a gap defined adjacent to the
forming surface.
27. The method of claim 21 further comprising, forming a dispensing
hole in the hollow formations.
28. The method of claim 27 wherein forming a dispensing hole
comprises laser radiating the hollow formations to burn through the
sheet-form member.
29. The method of claim 27 wherein forming a dispensing hole
comprises mechanically piercing the hollow formations.
30. The method of claim 21 wherein mold pins extend into the
forming cavities from a body of the forming surface.
31. The method of claim 21 further comprising, weakening a discrete
area of the hollow formations.
32. The method of claim 31 wherein weakening comprises laser
radiating the hollow formations for a period of time chosen to
decrease the structural strength of a discrete area of the hollow
formations without burning through the sheet-form member.
33. The method of claim 21 further comprising filling the hollow
formations with a flowable substance.
34. The method of claim 33 further comprising, after filling,
bonding a backing layer to the sheet-form member to form a
multiplicity of substantially enclosed chambers.
35. The method of claim 34 wherein the flowable substance comprises
a component that volatilizes when exposed to the atmosphere.
36. The method of claim 33 further comprising choosing the flowable
substance from a group including: a medicament appropriate for
topical application; an antibiotic; an analgesic; components that
reduce transmission of ultraviolet radiation; and components that
repel insects.
37. A hook component of a hook and loop fastener system, the hook
component comprising: a field of hollow loop-engageable elements
projecting from a base layer; a flowable substance within the
hollow elements; and a dispensing feature enabling dispensing of
the flowable substance in response to deformation of the
loop-engageable elements.
38. The hook component of claim 37 wherein backing material and the
hollow loop-engageable elements define cavities containing the
flowable substance.
39. The hook component of claim 37 wherein the hollow
loop-engageable elements comprise hooks having loop-engageable
heads.
40. The hook component of claim 37 wherein the hollow
loop-engageable elements dispense the flowable substance when
deformed.
41. The hook component of claim 37 wherein the hollow
loop-engageable elements are deformable in response to
disengagement of the hook component from a mating fastener
component.
42. The hook component of claim 41 wherein the hollow
loop-engageable elements dispense the flowable substance when
deformed.
43. A method of forming a sheet form product, the method
comprising: forming a multi-layer sheet having a first layer
forming a first broad surface of the multi-layer sheet; pressing
the multi-layer sheet against a forming surface with the first
layer contacting the forming surface such that the multi-layer
sheet substantially conforms to and fills a multiplicity of
inwardly extending forming cavities in the forming surface;
removing the multi-layer sheet from the forming surface; removing
the first layer from remaining portions of the multi-layer sheet,
the remaining portions of the multi-layer sheet defining a member
having stems of fastener elements integrally molded with and
extending from a sheet-form base.
44. The method of claim 43 wherein the first layer is interposed
between the remaining portions of the multi-layer sheet and the
forming surface when the multi-layer sheet is pressed against the
forming surface.
45. The method of claim 44 wherein the remaining portions comprise
additives.
46. The method of claim 45 wherein the additives comprise
materials, such as titanium dioxide or calcium carbonate, that
increase the rate of accumulation of contaminating material on the
surfaces the resin and additives contact and the method further
comprises sizing a thickness of the first layer to limit contact
between the forming surface and the remaining portions.
47. The method of claim 45 wherein the additives comprise materials
that increase abrasive characteristics of the remaining portions
and the method further comprises sizing a thickness of the first
layer to reduce wear on the forming surface from the remaining
portions.
48. The method of claim 44 further comprises sizing a thickness of
the first layer based on sizes of irregularities in the forming
surface.
49. The method of claim 43 further comprising selecting materials
for the first layer that have a first flexural modulus and
materials for the remaining portions that have a second flexural
modulus such that the second flexural modulus is greater than the
first flexural modulus.
50. The method of claim 49 wherein the second flexural modulus is
greater than 300,000 pounds per square inch.
51. The method of claim 50 wherein the second flexural modulus is
greater than 500,000 pounds per square inch.
52. The method of claim 51 wherein the second flexural modulus is
greater than 750,000 pounds per square inch.
53. The method of claim 49 wherein removing the multi-layer sheet
from the forming surface comprises compressing the first layer
between the forming surface and remaining portions.
54. The method of claim 49 further comprising forcing the remaining
portions through the first layer.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims priority to provisional U.S.
Application Ser. No. 60/664,405, filed Mar. 23, 2005, the entire
contents of which are hereby fully incorporated by reference.
TECHNICAL FIELD
[0002] This description relates to molding touch fastener elements,
such as hooks for hook and loop fastening.
BACKGROUND
[0003] Touch fastener elements are molded in arrays for loop
engagement. Many such fastener elements are very small, such as
less than 0.5 millimeter in height, and are molded integrally with
a flexible, sheet-form base. Some touch fastener elements are
hook-shaped, and some are mushroom-shaped. Male touch fastener
elements are shaped for releasable engagement with a field of loops
or with another field of male touch fastener elements. Often the
available fastener element shapes are limited by the molding
method. For example, some shapes cannot be molded in closed
cavities, as the molded elements cannot be pulled from the cavities
without damaging the engageable heads. Furthermore, the fineness of
particular features is limited by resin flow properties. Better
fastener element formation methods are desired, as well as improved
touch fasteners.
SUMMARY
[0004] According to one aspect, a product includes a base layer and
a multiplicity of protruding hollow formations, the protruding
formations unitarily formed with and extending upward from an upper
surface of the base layer, the hollow formations and base layer
formed of thermoplastic applied under pressure against a forming
surface having forming cavities and the base layer having a back
surface including interior surfaces of the hollow formations
comprising a parting surface from which a second thermoplastic
filling the hollow formations has been peeled. Embodiments of this
aspect can include one or more of the following features.
[0005] The protruding formations can be elements of fastener
formations. In some embodiments, the fastener elements are loop
engageable formations that can be molded hooks. In other
embodiments, the fastener elements are cylindrical hollow stems
that can have post-formed distal ends. Alternatively, the
protruding formations have sinusoidally curved upper surfaces
(which can provide a skin-friendly texture), are cylindrical hollow
stems (which can allow for easy removal from mold cavities), or are
cones (which can provide a shape that is easy to truncate).
[0006] The protruding formations can have a height above the base
layer of less than about 0.500 inches. In important cases, as where
the projections form loop-engageable fasteners, the protruding
formations have a height above the base layer of less than about
0.100 inches, but greater than about 0.005 inch. The protruding
formations can have a height above the base layer of less than
about 0.030 inches.
[0007] The product also can include a flowable substance filling
the hollow formations. In some embodiments, the flowable substance
is a liquid and, in other embodiments, the flowable substance is a
fine powder.
[0008] The product also includes a backing layer at least part of
which forms a bond to a surface of the base layer so that the
multiplicity of protruding formations cooperate with the backing
layer to define a multiplicity of substantially enclosed chambers
containing the flowable substance. In some embodiments, the bond
between the base and backing layer substantially seals individual
chambers so that movement of the flowable substance out of the
individually sealed chambers through the base layer is limited by
the backing layer. In other embodiments, the bond between the base
and backing layers substantially seals groups of the chambers,
individual chambers within the groups of chambers remaining in
fluid communication with each other while movement of the flowable
substance out of the groups of chambers is limited by the backing
layer.
[0009] In some embodiments, at least 10 percent of the protruding
formations also define an upper opening for dispensing the flowable
substance. The opening can be sized such that surface tension and
viscosity substantially retain the flowable substance within the
chambers until the protruding formations deform in response to
applied pressure. The product can also include a sealing strip
covering the upper openings, the sealing strip removable to
dispense the flowable substance through the upper openings.
Alternatively, the protruding formations can contain discrete areas
whose structural strength is weaker than the structural strength of
other areas of the protruding element.
[0010] In some embodiments, the flowable substance comprises a
component that volatilizes when exposed to the atmosphere.
Dispersion of the volatile component can release a generally
aesthetically-pleasing odor. In these embodiments, the
thermoplastic forming the hollow formations can be chosen from
thermoplastics whose permeability allows dispersion of the volatile
component through the thermoplastic.
[0011] In some applications, the product includes a disposable,
absorbent undergarment wherein the base layer, hollow formations,
flowable substance, and backing layer are attached to the
disposable, absorbent undergarment. In other applications, the
product includes a container liner portion wherein the base layer,
hollow formations, flowable substance, and backing layer are
attached to the container liner portion. In still other
applications, the product includes a sampler portion wherein the
base layer, hollow formations, flowable substance, and backing
layer are attached to the sampler portion with a sealing layer
covering the first portion and limiting movement of the flowable
substance out of the first portion, the sealing layer removable to
dispense the flowable substance.
[0012] In some embodiments with a flowable substance, the flowable
substance includes a medicament appropriate for topical
application. The medicament can include an antibiotic or an
analgesic. The flowable substance can include components that
reduce transmission of ultraviolet radiation. The flowable
substance can include components that repel insects.
[0013] In another aspect, a method of forming a sheet-form product
includes providing a forming surface having a multiplicity of
inwardly extending forming cavities and forming a multi-layer sheet
in the interior of which is a parting surface defined by materials
of limited compatibility, material of the sheet lying on each side
of the parting surface having peelable tensile strength. The
multi-layer sheet is pressed against the forming surface to cause
the multi-layer sheet to substantially conform to and fill the
cavities; and the multi-layer sheet is peeled apart at the parting
surface, whereby material directly engaging the forming surface
defines a sheet-form member having a multiplicity of hollow
formations. Embodiments of this aspect can include one or more of
the following features.
[0014] The forming cavities can define at least stems for fastener
elements. The forming cavities can define cylindrical formations or
loop engageable formations such as molded hooks. Alternatively, the
forming cavities can define sinusoidally curved surfaces, cones, or
cylindrical hollow stems.
[0015] The forming cavities can extend into the mold roll a
distance less than about 0.100 inches. The forming cavities can
extend into the mold roll a distance less than about 0.030
inches.
[0016] Forming a multi-layer sheet can include continuously
introducing a first molten thermoplastic and a second molten
thermoplastic into a gap defined adjacent to the forming surface.
Continuously introducing can include extruding the molten
thermoplastics as a molten sheet from a co-extruder die.
[0017] In some embodiments, the method also includes forming a
dispensing hole in the hollow formations. Forming a dispensing hole
can include laser radiating the hollow formations to burn through
the sheet-form member. Alternatively, forming a dispensing hole can
include mechanically piercing the hollow formations.
[0018] In some embodiments, mold pins extend into the forming
cavities from a body of the forming surface.
[0019] In some embodiments, the method also includes weakening a
discrete area of the hollow formations. Weakening can include laser
radiating the hollow formations for a period of time chosen to
decrease the structural strength of a discrete area of the hollow
formations without burning through the sheet-form member.
[0020] The method can also include filling the hollow formations
with a flowable substance. In some embodiments, the method also
includes, after filling, bonding a backing layer to the sheet-form
member to form a multiplicity of substantially enclosed chambers.
In some embodiments, the flowable substance includes a component
that volatilizes when exposed to the atmosphere. Dispersion of the
volatile component can release a generally aesthetically-pleasing
odor. The sheet-form member can be formed of a thermoplastic chosen
from thermoplastics whose permeability allows dispersion of the
volatile component through the thermoplastic. In some embodiments,
the flowable substance includes a medicament appropriate for
topical application. The medicament can include an antibiotic
and/or an analgesic. In some embodiments, the flowable substance
comprises components that reduce transmission of ultraviolet
radiation. In some embodiments, the flowable substance comprises
components that repel insects.
[0021] In another aspect, a hook component of a hook and loop
fastener system includes a field of loop-engageable hollow elements
projecting from a base layer. It also includes a flowable substance
within the hollow elements; and a dispensing feature enabling
dispensing of the flowable substance in response to deformation of
the loop-engageable elements.
[0022] In some embodiments, a backing material and the hollow
loop-engageable elements define cavities containing the flowable
substance.
[0023] The hollow loop-engageable elements can include hooks having
loop-engageable heads.
[0024] In some embodiments, the hollow loop-engageable elements are
deformable in response to stress between about 0.1 and 2 pounds per
inch width of the product. The hollow loop-engageable elements can
be deformable in response to disengagement of the hook component
from a mating fastener component. Alternatively, the stress can be
applied by direct pressure applied by a user pressing on the
elements. The hollow loop-engageable elements can dispense the
flowable substance when deformed.
[0025] In an aspect, a method of forming a sheet form product
includes forming a multi-layer sheet having a first layer forming a
first broad surface of the multi-layer sheet; pressing the
multi-layer sheet against a forming surface with the first layer
contacting the forming surface such that the multi-layer sheet
substantially conforms to and fills a multiplicity of inwardly
extending forming cavities in the forming surface; removing the
multi-layer sheet from the forming surface; removing the first
layer from remaining portions of the multi-layer sheet, the
remaining portions of the multi-layer sheet defining a member
having stems of fastener elements integrally molded with and
extending from a sheet-form base.
[0026] In some embodiments, the first layer is interposed between
the remaining portions of the multi-layer sheet and the forming
surface when the multi-layer sheet is pressed against the forming
surface. The remaining portions can include additives. In some
instances, the additives include materials, such as titanium
dioxide or calcium carbonate, that increase the rate of
accumulation of contaminating material on the surfaces the resin
and additives contact and the method further comprises sizing a
thickness of the first layer to limit contact between the forming
surface and the remaining portions. In some instances, the
additives comprise materials that increase abrasive characteristics
of the remaining portions and the method further comprises sizing a
thickness of the first layer to reduce wear on the forming surface
from the remaining portions.
[0027] In some embodiments, the method also includes sizing a
thickness of the first layer based on sizes of irregularities in
the forming surface.
[0028] In some embodiments, the method also includes selecting
materials for the first layer that have a first flexural modulus
and materials for the remaining portions that have a second
flexural modulus such that the second flexural modulus is greater
than the first flexural modulus. In some instances, the second
flexural modulus is greater than 300,000 pounds per square inch
(e.g., greater than 500,000 pounds per square inch or greater than
750,000 pounds per square inch). In some instances, removing the
multi-layer sheet from the forming surface comprises compressing
the first layer between the forming surface and remaining portions.
In some instances, the method also includes forcing the remaining
portions through the first layer.
[0029] Hollow elements as described herein can be used in a variety
of settings to store and dispense flowable substances such as
fragrances, medicines, inks, and insect repellents. Such dispensers
can be used in a security device in conjunction with a seal and
configured to release fluids when the seal is broken. Such
dispensers can also be used to store substances such as lotions,
cleansers, and medicines in portable containers for convenient use
while, for example, traveling in a car or airplane. Hollow elements
can be configured with smooth surfaces for skin-friendliness.
Hollow elements can also be configured as fastener elements such as
molded hooks. Hollow fastener elements can be used as both
dispensers and fastener elements when filled with a suitable fluid
(e.g., in a security device application). Hollow fastener elements
(e.g., molded hollow hooks with empty central voids) are
anticipated to provide aggressive fastener characteristics and
improved flexibility relative to similar hooks with a solid core.
The methods of producing hollow elements (e.g., roll molding)
described herein provide an efficient technique producing such
fastener elements and dispensers using, for example, the upper
portions of multiple-layer substrates and discarding and/or
recycling the lower portions of the multiple-layer substrates.
[0030] In one aspect, a method of forming fastener elements
includes pressing moldable material against a forming surface
having a multiplicity of inwardly extending forming cavities using
a surface with protrusions aligned with the cavities. The moldable
material is pressed against the forming surface to cause the
moldable material to substantially conform to and fill the
cavities. The moldable material is removed from the forming
surface.
[0031] The use of multiple-layer substrates can also provide
increase in efficiency and improved product quality for molding
processes. A sacrificial layer adjacent the molding surface can
make in more feasible to include additives to the remainder of the
substrate that might otherwise damage the molding surface. For
example, a sacrificial layer can used to separate portions of
substrate containing coloring agents (which can increase
contamination of the molding surface) or containing metal pieces
(which can increase wear damage to the molding surface) from the
molding surface. In addition, constraints on producing mold surface
limits the minimum size of molded features (e.g., molded hook
heights, molded hook tip configurations). However, use of a
sacrificial layer (e.g., effectively the use of resin as part of
the tooling) can provide an approach for molding small fine
features. In both of these approach, the sacrificial layer can
subsequently be removed from the remainder of the substrate as part
of the process of forming a fastener product.
[0032] The details of one or more embodiments are set forth in the
accompanying drawings and the description below. Other features,
objects, and advantages will be apparent from the description and
drawings, and from the claims.
DESCRIPTION OF DRAWINGS
[0033] FIG. 1 is a highly magnified vertical cross-section view of
a hollow fastener hook element for hook and loop fastening.
[0034] FIGS. 1A and 1B are schematic side magnified views of an
ink-filled tamper evident fastener product incorporating the hollow
hook of FIG. 1, respectively, before and after disengagement of the
fastening.
[0035] FIG. 2 is a cross-section of a sheet-form product molded of
two adjoined resin layers.
[0036] FIG. 3 is a similar cross-section as the resin layers are
peeled apart.
[0037] FIG. 4 is a cross-section of the upper layer of the
sheet-form product of FIG. 2 after separation from the lower
layer.
[0038] FIG. 5 is cross-section of two dies extruding two resins to
form a single two-layer sheet.
[0039] FIG. 6A is a schematic diagram of a system for producing
small hollow elements on a web product.
[0040] FIG. 6B is a schematic diagram similar to FIG. 6A of an
alternate embodiment.
[0041] FIG. 6C is side view of a two-layer sheet of resins entering
the calender nip formed with a mold roll as shown in FIGS. 6A and
6B, with mold cavities indicated diagrammatically.
[0042] FIGS. 6D and 6E are cross-sections of resins entering mold
cavities at progressive stages as indicated in FIG. 6C.
[0043] FIG. 6F is a developed plan view of the surface of the mold
roll shown in FIGS. 6A and 6B.
[0044] FIGS. 7A through 7E are cross-sections of various hollow
element embodiments.
[0045] FIGS. 8A and 8B are cross-section views of a mold with a
protruding pin taken in, respectively, the cross-machine and
machine directions.
[0046] FIGS. 8C and 8D are cross-section views of molded hooks
produced by the mold of FIGS. 8A and 8B before and after the second
resin is removed.
[0047] FIG. 8E is a cross-section of a mechanical piercing station
for creating holes in hollow hooks.
[0048] FIGS. 8F-8H are, respectively, a side view, a larger-scale
side view, and a developed view of using a laser station for
creating holes in conical hollow elements.
[0049] FIG. 9 is a schematic diagram of a filling and sealing
apparatus.
[0050] FIGS. 9A and 9B are, respectively, plan and side views of
the developed surface of the pressure roll shown in FIG. 9.
[0051] FIGS. 9C and 9D are, respectively, cross-section and plan
views of a web product with filled elements as produced by the
apparatus shown in FIGS. 6 and 9.
[0052] FIGS. 10A and 10B are cross-sections of a scent-filled web
product for use in applications such as diapers, garbage can
liners, and perfume samplers, respectively, before and after
sealing tape is removed.
[0053] FIGS. 11A and 11B are cross-sections of an embodiment of a
fastener hook.
[0054] FIGS. 12A and 12B are cross-sections of an embodiment of a
fastener hook.
[0055] FIGS. 13A and 13B are, respectively, an embodiment of system
for molding hollow fastener elements and an embodiment of the
resulting fastener hook.
[0056] Like reference symbols in the various drawings indicate like
elements.
DETAILED DESCRIPTION
[0057] Hollow hooks are usable in a wide variety of applications.
For example, referring to FIGS. 1, 1A, and 1B, a hollow
loop-engageable fastener hook 10 has its internal hollow volume
sealed with backing material 12 to contain ink 14. The ink is
provided to produce a visual signal when the hook is disturbed. As
shown, hooks 10 engage loops 18 a fastener loop material to seal
bag 24. The action of opening bag 24 causes release of the ink to
provide a visual indication that the fastening has been opened, see
FIGS. 1 and 1B. For this purpose, hooks 10 are made of a flexible
material so that stress, exerted on the hooks 10 as the hooks bend
to release the loop 18, compresses the volume within the hooks 10
to dispense the ink 14 through a suitable aperture.
[0058] Referring to FIGS. 2 and 3, a system and method for forming
the hook depend on selection of formable thermoplastic resins 144
and 148, which, though suitable for being provided as a sheet A of
adjacent joined layers, have, or are treated or formulated to have,
limited compatibility. The term "limited compatibility" means that
the adjacent resins, (1) under face-to-face joined conditions, have
sufficient compatibility to form a coherent combined sheet A, in
which the resins of the adjacent layers do not substantially
diffuse into one another or otherwise form a tenacious bond, but do
have sufficient adherence to remain united during passage through a
forming process to jointly form projections, such as hooks B,
standing from the sheet and (2) under formed conditions, have such
limited adherence as to permit separation at parting surface by
peeling action, see FIG. 3. Furthermore these two separable resins
in the form of layers, or, these resin layers in combination with
other resin layers tenaciously joined to their oppositely directed
sides, must have peelable tensile strength. The term "peelable
tensile strength" means that the separable resins, or separable
resin groups, in practical thicknesses, have sufficient strength to
remain intact under peeling tension, such that respective separable
sheets D, E and inter-fitted small projections from these sheets,
such as the hook form elements B.sub.1 and B.sub.2, are separable
as coherent units by peeling, thus producing a sheet-form product,
F, see FIG. 4, having a field of hollow projections B.sub.1, and an
exposed parting surface. In preferred cases, referring to FIG. 5,
the starting sheet A of joined layers is formed by extrusion of
melted resin in which the resins do not substantially diffuse into
one another and the projections are formed by molding the
sheet-form resins while at a moldable temperature.
[0059] Referring to FIG. 6A, manufacturing system 100 is employed
to produce a thermoplastic web product carrying a field of small
hollow formations 104 on its surface. In a preferred form, the
system employs roll molding apparatus of the general type shown in
U.S. Pat. No. 4,872,243 issued to Fischer. In the present case, the
nip is fed from two extruder dies 118A and 118B. Referring to FIG.
6B, in an alternate embodiment, the nip of the molding apparatus is
fed by a co-extrusion die 118 in the general arrangement
illustrated in U.S. Pat. No. 5,945,193 issued to Pollard et al.,
the details of each of which being hereby incorporated by
reference.
[0060] Referring to FIGS. 6A and 6B, the manufacturing system 100
includes a roll molding apparatus comprising temperature-controlled
cylindrical mold roll 108, temperature-controlled cylindrical
pressure roll 112, and a suitable extrusion arrangement. In FIG.
6B, for instance, co-extruder die 118 fed by two extruders 116A, B.
The extruders 116A, B receive resin from respective feedboxes 114A,
B, preferably flow from the latter feed box mixing with reclaim
flow 114C in mixer 115. Mold roll 108 is followed by take-off roll
120, separator station 124, take-up roll 132, and reclaim grinder
128. Mold roll 108 has a field of small mold cavities 136 in its
peripheral surface, for example mold cavities shaped to form
projections of heights in the range between about 0.005 and 0.100
inch. Mold roll 108 and pressure roll 112 are counter-rotating
rolls that define nip 140.
[0061] In operation, flows of first and second resins from
feedboxes 114A, B, in many advantageous cases, the latter mixing
with a predominant flow of reclaim resin 114C from reclaim grinder
128, are introduced to extruders 116A, B. Extruders 116A, B shear
and melt resins 144, 148 and introduce the melted resins under
pressure into co-extrusion die 118. The co-extrusion die 118
extrudes molten resin in sheet-form comprised of two adhered layers
144, 148, as shown in FIG. 6C. The molten sheet is led into
calender nip 140. The motion of the counter-rotating surfaces draws
the molten sheet into nip 140. The pressure of nip 140 forces the
two layer molten resin sheet into mold cavities 136. The final
thickness t of a two layer base sheet is determined by the spacing
of the roll surfaces at the calender nip and is typically about
0.002 to 0.010 inch. The layer thicknesses and hook dimensions are
exaggerated for clarity of illustration and are not to scale.
[0062] As diagrammatically shown in the sequence of FIGS. 6D and
6E, during passage through the nip 140, the pressure of the nip
forces the face-to-face resins 144, 148 progressively into mold
cavities 136. A portion of the first resin 144, defining the upper
layer of the sheet, flows into each exposed mold cavity against the
surfaces bounding the cavity. The outer portion of this resin thus
assumes the cavity configuration while the body of this resin
remains integral with adjacent portions of the layer from which it
originates. A corresponding portion of the lower resin layer moves
with the upper resin to occupy the center region of each mold
cavity while it too remains integral with adjacent portions of its
layer. Based on selection of the resins to have limited
compatibility and peelable tensile strength, the two parts of each
projection along with their respective base layers, when
solidified, are separable by peeling.
[0063] Following nip 140, the thermoplastic continues on the
surface of the rotating temperature controlled (cooled) mold roll
through arc a until the resin is sufficiently solidified to enable
removal from the mold roll. The web is led from mold roll 108,
about a small takeoff roll, not shown, to roll 120 thence to
separator station 124 by applied tension. (Though, in some
embodiments, it can be advantageous to remove the second resin at a
later stage).
[0064] At separator station 124, the upper layer, carrying the
mold-shaped outer portions of the projections, is peeled from the
lower layer carrying the central portions of the projections,
producing two separated webs. This is accomplished by leading the
separating layers about opposed rolls, 124 A,B under tension
produced by downstream pulling arrangements, not shown. After
peeling apart, the upper base layer with its hollow projections 104
proceeds to take-up roll 132, and the lower base layer with its
projections is directed to reclaim grinder 128.
[0065] In alternate embodiments of the system without a separator
station, the web is initially stored on take-up roll 132 with the
two layers still attached to each other to be separated later, for
instance as the material proceeds into a filling system.
[0066] Thus, based upon selection of resins 144, 148 to have
limited compatibility and peelable tensile strength and use of
suitable operating conditions, the integrity of each resin layer is
preserved to enable molding and subsequent peeling apart while
having sufficient compatibility that the layers adhere to one
another and flow as a unit into the molding cavities 136. First
layer, comprising a field of hollow projections 104 extending from
the upper base layer has numerous uses, for instance in the
dispensing of liquid or powdery fluids or providing desirable,
crushable properties, while being capable of performing other
functions as well, such as fastening functions.
[0067] In general, the weight ratio of first resin 144 to second
resin 148 is selected based on the shape of the mold cavities, the
desired layer thickness of first resin 144 in the final product,
and any desired further functionality. For many preferred
embodiments, appropriate weight ratios range between approximately
1 to 2 to approximately 2 to 1. In one example, when forming
projections as loop-engageable fastener hooks, Pro-fax.RTM. SD242,
a polypropylene, available from Basell Company was selected as
first resin 144, and Affinity.RTM. PT1450, a polyolefin plastomer,
available from the Dow Chemical Company was selected as second
resin 148. A weight ratio of 1 to 1 was employed. In commercial
production, 80% reclaim and 20% fresh resin may be used for the
second resin although only fresh resin was used in this example. In
this example, single screw extruders 116 A,B were operated with the
SD 242 melt in the range of approximately 420 to 450 degrees F. and
the Affinity.RTM. PT1450 melt in the range of approximately 390 to
420 degrees F. These conditions take into consideration resin
characteristics such as the fact that SD 242 has higher melting
point than Affinity.RTM. PT1450. Other process variables such as
roll temperature and line speed were selected based upon the base
layer thicknesses, size and shape of the projections, and weight
ratios, using customary operator skills.
[0068] The distribution of mold cavities 136 in the peripheral
surface of mold roll 108 determines the distribution of hollow
elements 104. For example, the developed mold roll surface shown in
FIG. 6F has groups 160 of mold cavities 136 separated by flat mold
roll surface portions 164. This produces a product with islands of
hollow elements 104 separated by plain regions of connecting
material. As discussed below, such distribution patterns facilitate
sealing of the volume defined by the hollow elements. Mold roll 108
in this example also has registration mold cavities 165 to produce
registration features on the sheet of hollow hooks. In some methods
of manufacturing fastener products, fillers (e.g., titanium dioxide
(TiO.sub.2) or calcium carbonate (CaCO.sub.3)) are added to the
resin from which hooks are manufactured in order to affect the
color or other properties of the resulting fastener products.
However, it has been observed that filled resins can contaminate
tooling (e.g., cause buildup of material on mold roll 108) more
quickly than non-filled resins. Tool contamination is undesirable
as it can result in decreased hook performance, increased downtime
for tools and machines, and increased manufacturing costs
associated with chemical and personnel requirements for cleaning
and rebuilding the tools. In some embodiments, methods similar to
those described above can be used to reduce contamination of
tooling. For example, referring again to FIG. 6E, a "clean"
non-filled resin can be run in top layer 144 with a normal or
highly filled resin run in bottom layer 148. This results in
reduced tooling contamination, as filled resin layer 148 would
never touch the tooling (e.g., mold cavity 136). Systems
implementing such methods would differ from system 100 in that
lower layer 148 (rather than or in addition to upper layer 144)
would form at least part of a desired fastener product.
Consequently, lower layer 148 would be collected and stored (e.g.,
wound onto a storage spool) rather collected and recycled.
[0069] Similarly, in some methods, upper layer 144 can be used to
protect tooling surfaces from potentially abrasive additives in
resin of lower layer 148. In some instances, it is desirable to
include additives (e.g., glass, metal pieces, etc.) into resin to
stiffen the resulting fastener formations and/or to create barbs
and friction points for engaging loops. Such additives have the
potential to cause wear damage to mold cavities 136. However, the
additives can be included in bottom layer 148 and not in upper
layer 144 such that the upper layer serves as a sacrificial layer
which can reduce wear damage on mold cavities 136.
[0070] In some methods, upper layer 144 can be used to protect
fastener products formed from lower layer 148 from the tooling
surfaces (e.g., rather than or in addition to protecting the
tooling surfaces from components of the resin forming the lower
layer). Rough tooling surfaces (e.g., irregularities in tooling
surfaces as small as 0.0001 inch) in mold cavities 136 can
contribute to contamination, can cause difficulty in removal of
formations (e.g., fastener hooks) from the mold cavities, and can
result in loss of hook shape and functionality after removal from
the mold cavities. Consequently, ring cutting and polishing
processes are used to provide smooth mold cavities 136. The costs
associated with the cutting and polishing processes can be reduced
when the bottom layer 148 of hooks is the primary layer to be used
as surface roughness issues may no longer be a problem. Upper layer
144 can provide a smooth surface that, when separated from the
bottom layer 148, will leave the bottom layer in its desired
shape.
[0071] Apparatus 100 is capable of producing small (i.e. height of
less than about 0.050 inch) hollow elements 104. For example, the
resins discussed above have been used to produce hollow
loop-engageable fastener hooks 104 as shown in FIG. 7A with an
overall height h.sub.1 of approximately 0.023 inch, a crook height
h.sub.2 of approximately 0.005 inch, and width w of approximately
0.013. These exemplary hollow hooks 104 were formed with individual
void volumes of approximately 1.times.10.sup.-6 inch.sup.3. As is
apparent, the projections 104 shown in FIGS. 6A and 6B as well as
the mold cavity outlines of FIG. 6C are not to scale but rather are
shown to illustrate their location relative to mold roll 108 and
other components of apparatus 100. Other element shapes, such as
semi-spheres having diameter of 0.005 to 0.010 inch, can be
produced by corresponding designs of mold cavities 136. For
example, 176 as shown in FIGS. 7B and 7C, skin-friendly products
are made of rounded dispensers 200 of first resin 144. Similarly,
as shown in FIG. 7D, hollow stem dispensers 204 are produced by
forming hollow stems in straight cylindrical mold cavities, in some
cases by subjecting the distal ends of stems 204 to heat and
pressure of a post-forming process, as by flame or radiant heating
optimally followed by passing through a calender nip of a
post-forming process, loop-engageable heads are formed, e.g. of
mushroom or flat-top configuration, the latter shown in FIG.
7E.
[0072] As discussed above, second resin 148 is reclaimed and reused
after being removed from hollow formations to reduce process costs.
Due to gradual thermal degradation and mixing with first resin 144,
it is necessary to replace second resin 148. It is presently
anticipated that this will be accomplished by making the feed to
extruder 116B approximately 80% reclaimed second resin 148 from
grinder 128 and 20% fresh second resin 148. However, under
different operating conditions, second resin 148 replacement will
be performed using different ratios reclaimed to fresh resin or
even on a batch basis, replacing all of the second resin from time
to time.
[0073] For many embodiments adapted to dispensing fluids from the
hollow volumes or otherwise having provision for communication
between the hollow volumes and the exterior, upper openings 150 are
formed in hollow elements 104. Referring to FIGS. 8A and 8B, in one
embodiment, mold cavities are provided with mold pins 152 that are
shaped to form upper openings 150. Mold pin 152 is dimensioned to
extend from the body of mold roll 108 through first resin 144 into
second resin 148. Referring to FIGS. 8C and 8D, when take-off roll
120 removes resins 144, 148 from the peripheral surface of mold
roll 108 after solidification, molding apparatus 100 has formed
two-resin hooks 156. After peeled separation of the layers, hollow
hooks 104 remain with a hole 150 through a wall of each hook.
[0074] In other embodiments, as illustrated in FIG. 8E, reciprocal
piercing pins 178 are caused to pierce two-resin hooks 156 at
mechanical piercing station 166a while the material is supported by
support member 180. In certain embodiments of this aspect,
mechanical piercing station 166a is located between takeoff roll
120 and stripping station 124, thus second resin 148 is present
during the piercing action and provides interior support as pins
178 are driven through first resin 144. In one example, mold roll
108 includes mold cavities that mold registration features 165 on
the web (FIG. 6F). These are engaged to provide positive
registration between hooks and the piercing pins to ensure proper
alignment during the operation. In other embodiments, other
alignment systems are employed, examples being based on optical
tracking of features or of marks provided on the web.
[0075] In other embodiments, as illustrated in FIGS. 8F-8H, a laser
beam 184 burns holes through first resin 144. Optional laser
station 166b is preferably located between stripping station 124
and take-up roll 132. Laser 184 or a suitable reflecting mirror is
mounted on a translating member 188 to provide a side-to-side
motion 192 sweeping the laser beam along rows of hollow elements. A
registration system, such as one of those described above, is
employed to assure alignment of the laser beam with the desired
regions for laser action. In a further embodiment, the laser energy
is controlled to selectively weaken discrete areas of the hollow
elements rather than creating complete holes through first resin
144. The remaining resin membrane preserves fluid tightness while
enabling opening of passages by a suitable activating action such
as by applying bursting pressure to the membrane. Those skilled in
the art will recognize there are a variety of other ways that holes
can be formed in hooks and elements within the spirit and scope of
the present invention. For example, a hot knife or hot wire can
horizontally cut across the top of conical projections.
[0076] Hollow elements on the thermoplastic web are filled using a
variety of filling techniques. In the embodiment shown in FIG. 9, a
supply conduit 168 introduces dispensable component 170 to the back
of a sheet of hollow elements 104. Doctor blade 172 pressures
dispensable component 170 into hollow elements 104 while removing
excess. In the case of hollow volumes that are difficult to fill,
vent passages are provided in hollow elements 104 to allow air to
escape while hollow elements 104 are filled. In another example,
the sheet is passed through a bath of fluid with the back of the
hollow volumes of the formation directed upwardly, by which the
volumes are filled.
[0077] Following filling, provision is made to enclose the fluid.
In certain embodiments, this is achieved by applying a backing
member. Referring to FIG. 9, after filling, sheets of hollow
elements 104 and backing material 176 are fed between laminating
roll 180 and pressure roll 184. Hollow elements 104 are distributed
in islands separated by regions of plain connecting material. As
shown in FIGS. 9A and 9B, pressure roll 184 has surface recesses
192 between mating surfaces 196 that correspond, respectively, with
islands of hooks 104 and bands of connecting material. Thus,
backing material 176 is bonded at the plain bands to the sheet of
hollow hooks using, for example heat and/or pressure, without
compressing hooks 104. Examples of appropriate backing materials
include but are not limited to a pressure-sensitive adhesive or a
resin sheet compatible with the first resin.
[0078] A sheet product produced by the process has regions of
projections 104 separated by element-free regions as shown in FIGS.
9C and 9D. The resin layer 144 may not be bonded to backing
material 176 in regions of elements 104. In this case, dispensable
component 170 can migrate between elements 104. In alternative
embodiments, other methods of sealing (such as, for example,
ultrasonic sealing or thermoplastic sealing using, as the backing
material 176, a preheated film that is very compatible with first
resin 144) achieve bonding between first resin 144 and backing
material 176 between individual elements 104 or small groups of
elements so as to individually seal elements 104 or small groups.
This is facilitated by providing a low density of elements 104 to
minimize interference of filler with the seal to backing material
176.
[0079] In embodiments employed for dispensing, pressure acts to
squeeze dispensable component from the hollow hooks. For this
purpose, first resin is chosen to be flexible to produce hooks that
are sufficiently deformable for the particular application. As
discussed above, the dispensing exit for the dispensable component
can be a hole or a weak spot that is opened by the application of
pressure or other conditions of use. For example, a user can apply
such pressure by pressing directly on a product to dispense a
topical medicament. In another embodiment, some of the hooks of the
tamper-evident fastener product described above dispense ink as
they deform in response an applied peeling force of between about
0.1 and 2 pounds per inch width of the product.
[0080] Hole size and filler viscosity determine how easily
dispensable component is dispensed and are chosen based on the
characteristics and rate of flow desired for a particular
application. In embodiments with holes, surface tension and
viscosity of the fluid and the properties of the resin such as
surface energy bias dispensable component to remain inside hollow
elements until pressure is applied. In some embodiments, these may
be sufficient to secure the fluid. In other cases, a membrane
covers the dispensing holes, or a plugging material is employed. In
embodiments with a weak spot, use of a suitable rupturable resin is
appropriate. Alternatively, the tip of the hook may be treated to
render it susceptible to opening.
[0081] Hollow hooks and hollow dispensers of other forms are usable
in a wide variety of applications. In FIG. 1, a tamper-evident
fastener hook was shown. In another example, hollow hooks or
dispensers are filled with other functional fluids. Referring to
FIGS. 10A and 10B, dispensers 200 are filled with a scented fluid
208 prior to the holes being closed with a sealing tape 212 as
shown in FIG. 10A. Such dispensers 200 are usable in products such
as garbage bags and diapers where it is desirable to release a
scent when the products are contacted during use. Sealing tape 212
also makes such dispensers useful for products such as
scratch-and-sniff perfume sampler inserts for magazines where it is
desirable to prevent inadvertent release of scented fluid 208.
Removal of sealing tape 212 releases the scented fluid, see FIG.
10B.
[0082] Other appropriate fillers for hollow hooks and dispensers
include but are not limited to suntan lotion, cosmetics, insect
repellents, and medicines including topical anesthetics and
antibiotics in fluid or powder form. Hollow hooks and hollow
dispensers are also usable in feminine care products.
[0083] As has been indicated, appropriate characteristics for a
dispensable component depend on the planned application and
construction of the dispensing formations. However, in general, it
is desirable that the dispensable component have a high viscosity
in order to minimize leakage. Fillers with a viscosity of
approximately 1,000 centipoises or higher are presently
contemplated.
[0084] In some embodiments, stiff materials (e.g., rigid PVC,
polyester polyethylene terephthalate, highly filled resins, or even
moldable metal) can be processed in a roll molding apparatus for
hook formation. Fastener products manufactured from stiff materials
(e.g., materials with a flexural modulus greater than about
300,000, 500,000, or 750,000 pounds per square inch) can provide
desirable high strength fastening properties (peel, shear,
tension). However, it is difficult to process stiff materials in a
roll molding apparatus with mold roll 108 made of metal because the
material being molded into fastener hooks must be flexible to bend
as the hooks are pulled from mold cavities 136. In a dual-layer
process to form fastener hooks from stiff material, moldable stiff
material is run in bottom layer 148 and a compressible material
(e.g., sanoprene, low density polyethylene, urethane, or material
with a compressive yield strength less than 20 MPa) is run in upper
layer 144. Thus, as tension is exerted to remove the web of dual
layer material from mold roll 108 fastener elements of the stiff
material compress the top layer 144 as the adjacent layers 144, 148
are pulled from mold cavities 136. Upper and lower layers are
subsequently separated.
[0085] Similarly, in some embodiments, use of a compressible
sacrificial layer can enable production of hook shapes that would
be otherwise difficult or impossible to produce through a roll
molding process. For example, referring to FIGS. 11A and 11B, a
hook 205 with a steep long crook 207 would be difficult to remove
from mold cavity 136 if made from a material with a high enough
flexural modulus to provide the hook with sufficient strength
properties to function as a fastener element. However, sacrificial
layer 201 can be formed of a material a compressible material that
would allow a lower layer 203, formed of a stiffer material, to
compress into the sacrificial layer as hook 205 is removed from
mold cavity 136. The shape of hook shape 205 can provide improved
strength properties (peel, shear, tension) relative to the fastener
elements as shown in FIGS. 2-4.
[0086] Similarly, in some embodiments, fastener hooks are formed
with crooks facing in a substantially cross-machine direction as
disclosed in U.S. Pat. No. 6,224,807, the entire contents of which
are incorporated herein by reference. In this context, machine
direction refers to the direction substantially aligned with the
rotation of the mold roll and cross-machine direction is the
direction along the axis of the mold roll and substantially
perpendicular to the machine direction. Cross-machine direction
facing hooks tend to have a twisted crook because the hooks face
cross-machine direction but are pulled out in the machine
direction. This tendency can be reduced through the use of a
compressible sacrificial layer, as discussed above, which would
allow cross-machine direction facing cavities to be filled with
resin and the resulting hook be removed from the mold cavity with
reduced twisting of crook. The sacrificial layer would take the
brunt of the twist, and the lower layer would partially compress
the upper layer during removal from the mold cavity, thus reducing
the crook twist.
[0087] Referring to FIGS. 12A and 12B, in some embodiments,
material (e.g., polymer resins) for two layers 211, 213 can be
chosen and processed such that the bottom layer 211 extends through
the top layer 213. For example, a fractional melt flow resin can be
run as top layer 213 and frozen off quickly such that bottom layer
211 is forced through the top layer to complete the cavity fill,
such that the two layers together form hooks 214 with stems 217
whose thickness is sufficient that the stems can be used to pull
the hooks out of a mold cavity. Top layer 213 is then removed,
leaving the bottom layer as a hook 215 with a thin stem 217 but a
large head 219. If the resulting hook 215 was molded in final form
in a fixed mold cavity without second layer 213, the hook would be
"mold-locked" and would not be removable from the cavity.
Large-headed hooks 215 provide good strength properties (peel,
shear, tension), at least in part because the relatively flexible
stems allow the hook to bend to follow the load, the extra
deflection increasing the number of engaged hooks that develop
loading at any given time.
[0088] Other approaches can also be used to form hollow elements.
Referring to FIGS. 13A and 13B, a system 300 includes an extruder
310 which feeds molten resin 312 into nip 313. Nip 313 is defined
between a pressure roll 314 and a mold roll 316. Pressure roll 314
includes protrusions 317 extending outward from a peripheral
surface 319 of the pressure roll. Protrusions 317 are sized to fit
with mold cavities 321 defined in mold roll 316. Pressure roll 314
and mold roll 316 are oriented such that protrusions 317 align with
mold cavities 321. As molten resin 312 enters nip 313, protrusions
317 displace some of the resin that would otherwise be present in
mold cavities 321. Takeoff roll 330 and removes resin 312 from mold
roll 316 after the resin has solidified sufficiently to apply
removal tension. Resulting fastener web 332 includes hooks 334 with
interior cavities 336 and solid crooks 338. Interior cavities 336
provide hooks 334 with increased flexibility for improved
engagement while crooks 338 provide hooks 334 with good strength
properties.
[0089] A number of embodiments have been described. Nevertheless,
it will be understood that various modifications may be made
without departing from the spirit and scope of the invention. For
example, in some embodiments, a dispensable component is applied
discretely in the vicinity of hollow elements using a jetting
process analogous to the processes used by ink-jet printers.
[0090] Accordingly, other embodiments are within the scope of the
following claims.
* * * * *