U.S. patent application number 09/738501 was filed with the patent office on 2002-08-22 for drapable surface fastener and method of using same.
This patent application is currently assigned to Cape Cod Research, Inc.. Invention is credited to Gall, Brett M., Keohan, Francis L..
Application Number | 20020112325 09/738501 |
Document ID | / |
Family ID | 24968284 |
Filed Date | 2002-08-22 |
United States Patent
Application |
20020112325 |
Kind Code |
A1 |
Keohan, Francis L. ; et
al. |
August 22, 2002 |
Drapable surface fastener and method of using same
Abstract
A mechanical surface fastener intended to usefully conform to a
three-dimensional shape comprises a stemmed web having an array of
upstanding stems 10 distributed across both faces, and having
through holes 11 in the web 12 positioned in the spaces between the
stems. The mechanical surface fastener is used in a method of
improving the impact strength of molded articles comprising
sandwiching an effective amount of said fastener between layers of
said foraminous reinforcing material.
Inventors: |
Keohan, Francis L.;
(Kingston, MA) ; Gall, Brett M.; (Wareham,
MA) |
Correspondence
Address: |
Francis L. Keohan
Cape Cod Research, Inc.
19 Research Road
East Falmouth
MA
02536
US
|
Assignee: |
Cape Cod Research, Inc.
|
Family ID: |
24968284 |
Appl. No.: |
09/738501 |
Filed: |
December 18, 2000 |
Current U.S.
Class: |
24/452 |
Current CPC
Class: |
A44B 18/0061 20130101;
Y10T 24/2792 20150115; A44B 18/0069 20130101; A44B 18/0084
20130101 |
Class at
Publication: |
24/452 |
International
Class: |
A44B 011/25 |
Goverment Interests
[0001] The invention was made with Government support under
Contract No. DASG60-00-M-0119 awarded by the U.S. Army Space and
Missile Defense Command. The Government has certain rights to this
invention.
Claims
What is claimed is:
1. A drapable surface fastener having a web of material having two
sides and a plurality of stems extending from both sides of the
web, the web containing holes positioned in the spaces between the
stems to permit the web to usefully conform to a three-dimensional
shape.
2. The drapable surface fastener of claim 1, wherein the holes are
through holes and/or holes which substantially penetrate the
thickness of the web.
3. The drapable surface fastener of claim 1, wherein the holes are
substantially rectangular or diamond shaped.
4. The drapable surface fastener of claim 1, wherein the stems are
substantially cylindrical, rectangular, conical, pyramidal or
mushroom-shaped.
5. The drapable surface fastener of claim 1, wherein the stems are
uncapped and are substantially pointed.
6. The drapable surface fastener of claim 1, wherein one or more of
the stems have caps.
7. The drapable surface fastener of claim 1, wherein the web is
formed from at least one melt processable polymeric material.
8. The drapable surface fastener of claim 7, wherein the polymeric
material is nylon.
9. A composite part produced by the process comprising the steps
of: (a) providing sheets of foraminous reinforcing material; (b)
providing a mold having a cavity; (c) providing drapable surface
fastener having a web of material having two sides and a plurality
of stems extending from both sides of the web, the web containing
holes positioned in the spaces between the stems to permit the web
to usefully conform to a three-dimensional shape; (d) selectively
placing said foraminous reinforcing material and said drapable
surface fastener in said mold cavity; and (e) molding a composite
part from resin, said foraminous reinforcing material and said
drapable surface fastener, said part having enhanced mechanical
properties in desired areas due to said foraminous reinforcing
material and said drapable surface fastener being located in said
desired areas.
10. The part of claim 9, said placing step includes the step of
placing said foraminous reinforcing material and said drapable
surface fastener in alternating layers into said mold cavity;
11. The part of claim 9, wherein said foraminous reinforcing
material is selected from the group consisting of E-glass fibers,
S-glass fibers, graphite fibers, aramid fibers, and silicon carbide
fibers.
12. The part of claim 9, wherein said resin is formed from a
polymeric material selected from the group consisting of
polybismaleimide, polyamides, polypropylenes, polyesters, epoxys,
polyethylenes, and polyphenylene sulfides.
13. The part of claim 9, wherein said continuous strand material is
a woven cloth and/or a reinforcing mat formed from continuous
strand material.
14. The part of claim 9, wherein an effective number of said stems
hook into said foraminous material.
Description
FIELD OF THE INVENTION
[0002] The invention relates to stemmed web fasteners. More
particularly, the invention relates to improved web fasteners
capable of snugly fitting the contours of a three dimensional
shape.
BACKGROUND
[0003] Refastenable mechanical fastening systems based on hook and
loop fasteners are well known in the art. Typically, such fastening
systems comprise a web of material having a plurality of stems
extending from at least one side of the web. A stem means a
protrusion from a surface, such as a web, regardless of its shape,
length, length-to-width ratio, geometry or other
characteristics.
[0004] U.S. Pat. Nos. 4,056,593 and 4,959,265 disclose an early
method of extruding polymeric webs with upstanding stems, known as
stemmed webs. These early stemmed webs are formed of a single
material. Only one side of the web has stems and the web is a thin
continuous sheet. U.S. Pat. No. 5,951,931 discloses methods for
continuously manufacturing stemmed webs using a rotating die wheel.
As in other early versions, the web is a continuous sheet formed of
a single material and only one side has stems.
[0005] U.S. Pat. Nos. 5,393,475 and 6,106,922 disclose methods of
manufacturing stemmed webs with stems on both sides of continuous
sheets of material using two different materials. The multiple
components are formed together to enhance the mechanical
performance properties of the mechanical fastener.
[0006] Drapability means the ability to follow the contours of a
three-dimensional (3D) object without producing folds or wrinkles.
Heretofore, known stemmed webs have been structures comprising webs
which had unacceptable drapability for many applications. By way of
example, but not by way of limitation, said applications include
mechanical fastening of cloth prior to sewing, mechanical fastening
of flexible devices to conform to the contours of the human body,
as well as mechanical fastening of dry fiber reinforcements in
place within complex mold cavities prior to and during the
injection of resin into the mold cavity.
[0007] An object of the invention is to provide useful drapable
mechanical fasteners for use in the sewing of cloth.
[0008] An object of the invention is to provide useful drapable
mechanical fasteners for use in improving the comfort of devices
that are placed against or in proximity to the body of the wearer
to absorb and contain the various exudates discharged from the
body.
[0009] A further object of the invention is to provide useful
drapable mechanical fasteners for use in the manufacture of
composite materials from dry fabrics. The many potential advantages
of using dry carbon or glass fabrics for manufacturing complex 3D
shapes are described in Taylor: "RTM Material Developments for
Improved Processability and Performance", SAMPE Journal, Vol. 36,
No. 4, pp. 17-24 (2000).
[0010] In order to provide mechanical strength in composite
structures, foraminous reinforcing material is selected from the
group consisting of E-glass fibers, S-glass fibers, graphite
fibers, aramid fibers, and silicon carbide fibers. This reinforcing
material is placed in the cavity of a mold and injected with resin
is formed from a polymeric material selected from the group
consisting of polybismaleimide, polyamides, epoxys, polypropylenes,
polyesters, polyethylenes, and polyphenylene sulfides.
Unfortunately during the injection process viscous forces result
and these cause the reinforcing fibers to move from desired
locations to undesired locations. Sewing of the reinforcing
material to prevent this motion tends to break fibers and reduce
strength. Adhesives tend to weaken the strength of the
composite.
[0011] There is a need for stemmed webs, such as mechanical
fasteners, having a wider variety of properties to meet more varied
applications requiring improved drapability.
SUMMARY OF THE INVENTION
[0012] The present invention is a drapable surface fastener having
a web of material having two sides and a plurality of stems
extending from both sides of the web, the web containing holes
positioned in the spaces between the stems to permit the web to
usefully conform to a three-dimensional shape. The invention can
usefully stretch in all three directions so that its stretched
shape snugly fits the contours of a 3D shape. Depending on the
manufacturing process used to form the present invention, the holes
in the web are either through holes or are holes which
substantially penetrate the web.
[0013] The stems should be resistant to compression and bending,
and their tips preferably are substantially pointed to permit them
to penetrate easily into the interstices of a foraminous substrate,
even though they may be quite supple. Preferably the points are
blunt to avoid any cutting action. For most uses, each of the stems
should be in height less than the thickness of the foraminous
substrate used and in breadth less than 2 mm where they join to the
web.
[0014] Each of the stems preferably is substantially cylindrical,
rectangular, conical or pyramidal. Such stems can be given mushroom
shape by softening the tip of each to create a bulbous crown. A
mushroom-shaped stem can enhance the attachment of the novel
drapable web fastener to a foraminous substrate, as can projections
that have hooked crowns. Regardless of the shape of the stems,
their tips are preferably shaped to enhance penetration into a
fabric or other foraminous substrate without producing any cutting
action.
[0015] The holes in the drapable surface fastener preferably are
substantially rectangular or diamond shaped. Useful drapable
structures can be formed by compression molding of thermoplastic
films. Very thin films often block the holes so formed which are an
artifact of the compression molding process and which tear when the
invention is draped over a complex 3D object. A drapable stemmed
web comprising through holes can preferably be continuously
manufactured by the steps of:
[0016] 1. Two counter rotating die wheels having in their
circumferential surfaces a multiplicity of stem-forming cavities
connected together by grooves oriented in a diamond pattern;
[0017] 2. continuously supplying molten resin to a molten resin
induction port adjacent to said die wheels under a predetermined
resin pressure;
[0018] 3. molding the invention in an integral form along the
rotating die wheels while said stem-forming cavities and said
web-forming grooves are filled with said molten resin; and
[0019] 4. Separating the molded invention from said circumferential
surface of said die wheels and moving the invention in a traveling
path.
BRIEF DESCRIPTION OF THE DRAWING
[0020] FIG. 1 is a perspective view of a typical embodiment of the
drapable stemmed web of the present invention. The drapable stemmed
web has an array of upstanding stems 10 distributed across both
faces, and through holes 11 in the web 12 positioned in the spaces
between the stems to permit the web to usefully conform to a
three-dimensional shape. In the preferred embodiment, the web as
well as the stems are formed from a single tough flexible plastic,
such as nylon. However, the web can consist of any other material
or combination of materials that can be repeatedly bent without
fracturing. Especially preferred are materials that can be formed
from at least one melt processable polymeric material such as
polyethylene, polypropylene, vinyl, rubber, and
polyethylene-terephthalate. Also of utility are copolymers of
ethylene and propylene and copolymers of ethylene and
vinylacetate.
ILLUSTRATIVE ARTICLE OF USE
[0021] An illustrative and nonlimiting example of the usage of the
fastening system of the present invention in an article of
manufacture follows. A composite part according to the invention is
produced by the process comprising the steps of:
[0022] (a) providing sheets of foraminous reinforcing material;
[0023] (b) providing a mold having a cavity;
[0024] (c) providing drapable surface fastener;
[0025] (d) selectively placing said foraminous reinforcing material
and said drapable surface fastener in said mold cavity;
[0026] (e) molding a composite part from said foraminous
reinforcing material and said drapable surface fastener, said part
having enhanced mechanical properties in desired areas due to said
foraminous reinforcing material and said drapable surface fastener
being located in said desired areas.
[0027] Drapable mechanical fasteners for use in the manufacture of
composite materials from dry fabrics were formed according to the
invention by first compression molding nylon 6 in a two piece
aluminum mold. The mold surfaces were coated with mold release
spray before use. Nylon 6 pellets (Aldrich Chemical Company) or
sheets of nylon 6 film (Capron.RTM., Allied Signal Corp.) were
placed in the mold, the two halves aligned and the mold placed
between the heated platens of a Carver laboratory press. The
temperature of the mold was raised to about 230.degree. C. and a
force of approximately 1000 pounds applied to the mold. The
assembly was cooled the drapable surface fastener of the invention
demolded.
[0028] Seven dry sheets of woven graphite fiber (6K, IM-7,
5-harness satin, 380 g/m.sup.2 by Textile Products, Inc.) and six
dry sheets of drapable stemmed webs were alternatively stacked
within the inner cavity of a mold. The stems contacting the woven
graphite fiber and penetrated easily into the interstices of the
cloth to form a dry preform which conformed to the shape of the
cavity. A commercial epoxy (Ciba epoxy MY721-HY5200) was injected
into the mold and the resulting composite cured at 121.degree. C.
for 1 h and 177.degree. C. for 3 h to manufacture the composite
part of the invention.
[0029] As controls, two additional reinforced parts were molded
under exactly the same conditions except the drapable mechanical
fasteners of the invention were replaced by either nothing or by 5
percent by weight of fabric of a commercial tackifier resin
adhesive (Epon Resin, 2002).
MECHANICAL STRENGTH IN SHEAR
[0030] The mechanical strength of said three composites was
measured by first cutting test beams from along the direction of
the reinforcing graphite fibers. The interlayer adhesion was
measured by the interlaminar shear strength (ILSS) test according
to ASTM D 3518.
[0031] The apparent interlaminar shear strength (ILSS) was
calculated from linear beam theory, which relates maximum
transverse shear stress to the peak load and cross-sectional area
of the beam specimen.
1TABLE 1 Interlaminar Shear Properties of IM-7 Graphite Fiber
Composites Prepared with Different Preform Assembling Methods
Interply Fastening Method for Preform Composite Epoxy Resin
Drapable Property None Tackifier Fastener Fastener.sup.1 Weight
Fraction 0.00 0.00 3.99 (%) Volume Fraction 0.0 0.0 5.5 (%)
Tackifier.sup.2 Weight Fraction 0.00 4.16 0.00 (%) Volume Fraction
0.0 5.6 0.0 (%) Epoxy Weight Fraction 22.55 15.89 22.85 (%) Volume
Fraction 30.0 21.4 29.8 (%) Fiber Weight Fraction 77.45 79.95 73.14
(%) Volume Fraction 70.0 73.0 64.7 (%) Interlaminar 444 .+-. 41 411
.+-. 41 470 .+-. 33 Shear Strength (psi) 1. Fastener arrays
fabricated from nylon 6 2. Tackifier powdered Epon Resin 2002
(melt-applied to fabric before epoxy impregnation). 3. Assume
graphite fiber density = 1.77 g/cm.sup.3, epoxy density = 1.20
g/cm.sup.3, nylon density = 1.14 g/cm.sup.3, tackifier density =
1.19 g/cm.sup.3
[0032] The incorporation of the invention was not found to
significantly affect the interlaminar shear strength (ILSS) of the
graphite-reinforced epoxy laminates. Table 1 shows a slight
improvement in ILSS for the composites prepared according to the
invention over the samples prepared with tackifier, although the
difference in strength was less than one standard deviation in
magnitude.
IMPACT TESTING
[0033] An illustrative and nonlimiting example of the remarkable
improvement in impact strength of composites resulting from the use
of the invention follows.
[0034] Falling weight impact test specimens were prepared from
six-ply woven IM-7 carbon fiber fabric (5HS Weave, 6K,
380g/m.sup.2, 0.024 in thick, style #4114, Textile Products, Inc.)
and commercial epoxy resin MY721-HY5200 (Ciba Corp). According to
the invention, drapable surface fasteners with web heights greater
than the thickness of the fabric were used between the third and
fourth plies to obtain mechanically stable preforms. Tackified
fabric plies and non-tackified plies were used to prepare controls.
The test results are summarized in Table 2.
2TABLE 2 Drop Weight Impact Test Results for Composites Prepared
with Untreated, Tackified, and Mechanically-Fastened IM-7 Graphite
Fabric Preforms and MY721-HY5200 Epoxy Matrix Resin Interply
Fastening Method for Preform Composite Epoxy Resin Drapable
Property None Tackifier Fastener Fastener.sup.1 Weight Fraction
0.00 0.00 0.81 (%) Volume Fraction 0.00 0.00 1.2 (%)
Tackifier.sup.2 Weight Fraction 0.00 3.72 0.00 (%) Volume Fraction
0.00 5.0 0.00 (%) Epoxy Weight Fraction 22.33 17.40 17.51 (%)
Volume Fraction 29.8 23.3 24.6 (%) Fiber Weight Fraction 77.67
78.88 77.88 (%) Volume Fraction 70.2 71.7 74.2 (%) Average 0.075
.+-. 0.076 .+-. 0.083 .+-. Laminate 0.001 0.002 0.002 Thickness
(in) Specific Peak 34.0 39.6 46.8 Force (joules) Failure resin
resin resin Observations cracks, cracks, cracks, fiber tears fiber
tears fiber tears 1. Ciba epoxy MY721-HY5200 cured @ 121.degree. C.
for 1 h and 177.degree. C. for 3 h 1. Fastener arrays fabricated
from nylon 6 2. Tackifier = powdered Epon Resin 2002 (melt-applied
to fabric before epoxy impregnation). 3. Assume graphite fiber
density = 1.77 g/cm.sup.3, epoxy density = 1.20 g/cm.sup.3, nylon
density = 1.14 g/cm.sup.3, tackifier density = 1.19 g/cm.sup.3
[0035] The composites prepared from preforms assembled with
drapable surface fasteners showed significantly higher impact
resistance than the controls prepared from tackified and
non-tackified plies. This property enhancement is most readily
explained by the positive reinforcement provided between the
laminate plies by the fasteners.
[0036] Laminates were also prepared from 6 layers of 3/4 oz-E glass
chopped strand mat (M127, Vetrotex-CertainTeed) and a commercial
vinyl ester resin. The latter was a peroxide-initiated, thermal
cure brominated vinyl ester (CORVE-8441, Cook Composites Corp.).
The impact test results for these fiberglass composites based on
non-woven glass reinforcements are provided in Table 3.
3TABLE 3 Drop Weight Impact Test Results for Composites Prepared
with Untreated and Mechanically-Fastened Chopped E-Glass Strand Mat
Preforms and CORVE-844 Vinyl Ester Matrix Resin Interply Fastening
Method for Preform Composite Drapable Property None Fastener
Fastener.sup.1 Weight Fraction 0.00 1.62 (%) Volume Fraction 2.6
(%) Vinyl Ester Weight Fraction 33.24 31.07 (%) Volume Fraction
51.9 48.7 (%) Fiber Weight Fraction 66.76 67.31 (%) Volume Fraction
48.1 48.7 (%) Average 0.041 .+-. 0.053 .+-. Laminate 0.002 0.003
Thickness (in) Specific Peak 26.4 33.4 Force (joules) Failure resin
resin Observations cracks, cracks, fiber tears fiber tears
[0037] The composites prepared from preforms assembled according to
the invention with drapable web stems showed significantly higher
impact resistance than the controls prepared from unmodified
chopped strand mat plies. This property enhancement is most readily
explained by the positive inter-ply reinforcement afforded by the
nylon web arrays. An effective number of said fasteners hook into
said foraminous material and greatly improve impact strength.
[0038] Accordingly, while certain representative embodiments and
details have been shown for the purpose of illustrating the
invention, it will be apparent to those skilled in the art that
various changes in the product and processes described herein may
be made without departing from the scope of the invention, which is
defined in the appended claims.
* * * * *