Note: Descriptions are shown in the official language in which they were submitted.
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BACKG~OUND OF THE INVENTION
1 This invention relates to shoe manufacture and, par-
ticularly, to improvements in stiffening the shank region of
the shoe, which extends from the heel to the ball portion.
Most shoes typically require some means to rigidify and stiffen
the shank region. For many decades it has been substantially
universal practice to stiffen the shank region by attaching a
preformed steel, wood or wood on fiber shank piece to the bot-
tom of the insole of a lasted shoe assembly, before the out-
sole is attached so that after attachment of the outsole, the
shank lies between the insole and outsole.
The use of preformed shanks,such as steel shanks,for
this purpose has and still does present numerous problems.
Because of a wide variety of shapes, sizes and styles of
shoes, the manufacturer is required to maintain a very sub-
stantial inventory of preformed shanks. In order to insure an
adequate supply of the various shanks which may be required at
any time it is not uncommon for a manufacturer to overstock
his inventory. Not infrequently, a manufacturer finds that a
certain style or configuration of shank piece is no longer
useable because of continually changing shoe styles.
It is common shoe industry practice to make a "case"
of shoes at the same time in which the shoes in the case are
of varying styles and sizes. A machine operator applying
shanks to the bottoms of the insoles of the shoe in the case
typically will have before him a wide variety of preformed
shank pieces from which he must select the proper one to
,?
correspond to the particular shoe on which he is working.
There is a reasonable chance that the operator may select the
wrong shank piece for the particular shoe. Mismatching of
the shank and shoe presents complications in the subsequent
,
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1 manufacturing steps of that shoe as well as further difficul-
ties with the shoe after it has been completed and when it is
worn. Moreover, even when the proper shank piece has been
selected for a particular shoe, it is not uncommon for the
shank piece to fail to fit the curve of the last and insole
with the degree of conformity which is desired.
Also among the difficulties encountered with pre-
formed steel shank pieces is that they must be placed on the
insole in precisely the right location. They are typically
attached to the insole at one or two specific locations, as
by a nail, or adhesive, or a combination. Failure to properly
place the shank often interferes with subsequent nailing
operations, for example, when nailing the heel to the shoe.
In general, the preformed shank pieces are difficult to place
and require a significant degree of operator skill.
Even when a shoe having a steel shank is properly
manufactured, the steel shank may present difficulty when the
shoe is worn. After a time, the steel shank piece may work
its way loose from the repetitive flexing and the shoe de-
velops a squeak when worn. Remedial efforts to avoid asqueaky shoe have included taping of the st~el shank piece in
the hope that even if the shank does work loose, the taped
shank piece will be less likely to rub against either or both
of the insole and outsole. While this sometimes is effective,
at least until the tape itself wears through, it does add to
the cost and difficulty in manufacture of the shoe.
A further difficulty sometimes encountered with pre-
formed steel shank shoes is that the steel shank may be felt
by the wearer. Efforts to overcome this have included the
addition of a sheet or layer of cushioning material (sometimes
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1 called a "tuck") interposed between the ~hank and the insole.
Here, again, this adds ~o the cost and only further compli-
cates the manufacturing procedure.
THE PRIOR ART
The foregoing and other difficulties inherent in
the use of preformed steel shanks have been recognized in the
art for many years and numerous efforts, suggestions and
proposals have been made to remedy these difficulties. A1-
though there has been a long felt need for an effective re-
placement for the steel shank, no workable technique or system
has yet been developed. The almost ancient practice of
attaching a preformed shank such as a steel shankpiece still
is widespread and is almost universally employed in the manu- -~
lS facture of shoes. Although very substantial research and
development efforts have been made to apply a plastic mass -~
to an insole bottom, mold it and cure it in situ, all have -
run into serious difficulties which have precluded their use .~
commercially. Among the more difficult of these problems ~ -
has been in handling the plastic mass particularly when the
plastic is in the form of a fluent, tacky resin. Machine
parts tend to gum up with the resin and become operative.
Difficulties have been encountered with regard to premature
or tardy setting or curing of thermoplastic resins. A fur-
ther problem with some of the prior techniques is that in
the application, molding or curing of the resin temperatures
are reached which can damage the shoe materials. In those
instances where the shoe has already been lasted by a thermo-
plastic adhesive, as is common practice, the elevated tempe-
ratures required may soften the thermoplastic adhesive bonding
: . ~
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1 of other of the shoe L,aLtS and can cause them to delaminate
or othen~ise shift from their originally attached positions.
It is a~ong the general objects of the invention to
provide a system including new and improved articles of manu-
facture and methods by which a shank stiffener may be placed
and formed in situ on the bottom of an insole of a lasted
shoe assembly and which avoids the foregoing and other diffi-
culties which havé, thus far, been insurmountable in suhstantial
commercial practice.
SVMII~RY OF THE INVENTION
In its broad aspects, the invention relates to an
article for use as a shoe reinforcement in which the article
has a sleeve which surrounds a matrix of an externally activat-
able thermosetting resin. The sleeve and matrix are flexible
and deformable, as a unit, to enable the article to be applied
to a selected surface and to substantially conform to the shape
of the surface while in an unactivated condition. When so
applied, the article then may be activated.
One form of the invention employs a shank strip comprising
a mass of reinforcing fiber strands embedded in a matrix of a
thermosetting resin and catalyst mixture, surrounded by and
enclosed in an elongate sleeve impermeable to the mixture. The
sleeve preferably is of thermoplastic material and the strands
are preferably parallel fiberglass strands. The shank strip may
- be cut from an elongate rope of the material, which may be
pac];aged and stored on a reel until ready for use. The
thermoplastic sleeve precludes evaporation of any of the fluent
materials in the matrix and provides a long shelf life.
In use, a shank strip of desired length is cut from
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1 the rope and applied to and pressed lightly to the shank re-
gion of the insole bottom to conform with the insole contour. J
In one aspect of the invention, the bottom, insole-engaging
surface of the rope may be slit or perforated to expose the
S resinous matrix directly to the insole bottom so that it may
act as an adhesive. In an alternative technique, the outer
surface of the sléeve may be coated with an adhesive to faci-
litate temporary placement and attachment of the shank strip
: 4 a
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1 to the insole. In another case, the insole can be precoated
with an adhesive. In some instances, the sleeve material it-
self may be selected so that it will melt under the influence
of heat generated during the curing process and, itself, effect
a bond between the cured strip and the insole.
When the strip is in place, the thermosetting
resinous matrix is activated by an external stimulus such as
exposure to ultraviolet, infrared or high radio frequency
radiation or by applying heat in any manner such as by conduc-
tive heating. The heat is preferably applied locally to theshank strip and not to other parts of the shoe, for example,
by a radiant heater and in a manner which focuses, shields or
otherwise confines the radiant heat to the shank strip to avoid
heating other parts of the shoe assembly which may be attached
with a thermoplastic adhesive. The shank strip may be pre-
heated before it is applied to the shoe, for example, to a
temperature of the order of 150 F, and then applied to the
shoe. The strip then may be locally exposed, while on the shoe,
to a final heating to the activation temperature, for example,
two to four seconds. The sleeve-is preferably thermoplastic,
transparent and/or non-absorbing to the radiant energy to
enable direct heating of the resinous matrix. The resin can be
exothermic so that as it polymerizes and/or crosslinks its
temperature will be raised well above the melt temperature of
the thermoplastic sleeve to a level sufficient to cause the
thermoplastic sleeve to fuse in with and/or cross link with
the thermosetting matrix. The reaction also effects a full
and complete bond of the shank strip to the insole bottom.
The heat generated by the exothermic reaction can be localized
within the shank strip and does not adversely affect any nearby
~, ~
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1 shoe parts which may have been bonded by thermoplastic adhe-
sive. In some cases, the sleeve withstands the exothermic
and activating temperatures and remains in the final product.
In some instances, the resin matrix may tend to
bubble and expand as it cures, which might result in less
than desired uniformity in the shape of the shanks thus
formed. While in most instances, the expansion of the resin
may be controlled or avoided by carefully controlling the
conditions under which the shank strip is heated and cured,
the use of fine or sensitive control procedures preferably
is to be avoided under production conditions. The present
invention also includes an embodiment of the sleeve structure
which automatically controls the shape of the stiffener and,
therefore, reduces considerably the need for external controls.
- 15 In that embodiment, the carrier sleeve is provided with
., 1 .
upper and lower surfaces formed from separate sheets or strips
which may be of different materials. The strips are attached
to each other along their longitudinal edges which define
relatively wide margins. The upper strip of the surface of
the sleeve preferably is substantially transparent to the
radiant energy to permit the resin to be activated. In this
embodiment, the upper strip preferably is formed from a mate-
rial which will not melt, deteriorate or otherwise lose its
strength (for example, its tensile properties) from exposure
~.
to the radiant heat or from exothermal heat generated during
the curing process, at least until the resin has assumed a
substantially final shape. The lower, insole-engaging surface
- of the sleeve preferably i8 thermoplastic and will melt under
the influence of the applied and/or exothermally generated
heat to serve as an adhesive bond between the cured shank
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1 strip and the insole bottom. The wide margins of the carrier
sleeve provide a means by which the shank strip may be held
against the insole bottom to retain the carrier sleeve in place
during the activation and curing process. During activation
and curing, the tendency for the matrix to expand is resisted
by the upper surface of the carrier sleeve which serves to
confine the resin (and the thermoplastic strip) between it
and the insole bottom. This precludes the strip from assuming
a freely expanded shape which, in some types of shoes is un-
desirable. In a variant of this embodiment of the invention,
the upper strip of the carrier sleeve is formed from a
shrinkable film which will shrink during activation and curing
of the resin. As the upper strip shrinks, it causes the
resin matrix to be pressed into a cross-sectional shape having
a reduced height and smoothly tapered edges.
'~ .
DESCRIPTION OF THE DRAWINGS
The foregoing and other objects and advantages of
the invention will be understood more fully from the following
further description thereof, with reference to the accompanying
drawings wherein:
FIG. 1 is an illustration of a portion of the rope;
FIG. 2 is an illustration of a shoe bottom with a
; shank strip attached thereto;
FIG. 3 is a center cross-sectional view of the shoe
shown in FIG. 2;
FIG. 4 is an illustration of a severed shank strip -
showing a longitudinal slit in its underside to facilitate
exposure of the resinous matrix to the insole bottom;
FIG. 5 is a transverse sectional elevation, enlarged,
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1 illustrating the shank strip in place on the insole bottom
with the thermoplastic sleeve spread apart to expose the
thermosetting resin to the insole;
FIG. 6 is a transverse section showing the cross-
sectional configuration of the shank piece on the shoe as seenalong the line 6-6 of FIG. 2;
FIG. 7 is a transverse sectional illustration showing
the flattened ends of the shank strip on the insole bottom as
seen along the line 7-7 of FIG. 2;
FIG. 8 is a somewhat diagrammatic illustration of
: . the shank strip being heated by a radiant heater;
FIG. 9 is a sectional illustration as seen along the
line 9-9 of FIG. 8;
. . .
FIG. 10 is an enlarged transverse section of the
shank stiffener applied to the insole bottom with a longitudi-
. nal slit formed along the lower surface of the sleeve;
: FIG. 11 is an illustration of an alternative means
for exposing the thermosetting resin to the insolebottom;
FIG. 12 is a transverse sectional illustration of
the shank strip of FIG. 11 applied to the insole bottom;
FIG. 13 is an illustration of a further technique
for exposing the resin to the insole bottom;
. FIG. 14 is a longitudinal section illustrating the
manner in which the shank strip of FIG. 13 is applied to the ;
insole bottom;
FIG. 15 shows a still further technique for exposing
the resin to the insole bottom;
FIG. 16 is a transverse section illustrating the
~ .,
manner in which the shank strip shown in FIG. 15 is applied
to the insole bottom;
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1 FIG. 17 is a transverse sectional illustration of
the shank strip applied to the insole bottom without any
slitting or perforations in the sleeve;
FIG. 18 is an illustration of a shank strip in which
the sleeve has been slit at each of its ends on its opposite
transverse sides to facilitate spreading and feathering of
the ends of the shank strip;
FIG. 19 is a transverse section of the flattened,
feathered end of the shank strip of FIG. 18;
FIG. 20 is a somewhat diagrammatic illustration of
the manner in which the rope may be manufactured and wound on
a reel;
FIG. 21 is an illustration of a portion of another
embodiment of the rope from which a shank strip might be cut
in which the carrier sleeve is defined by a pair of strips,
sealed at their longitudinal edges to define margins;
FIG. 22 is an illustration of a shoe bottom with
the shank strip of FIG. 21 located on the shoe bottom;
FIG. 23 is a cross sectional illustration of a
modified form of the shank strip;
FIG. 24 is a sectional illustration of the shank
strip shown in FIG. 23 in place on the insole bottom as seen
along the line 24-24 of FIG. 22;
'r FIG. 25 is a somewhat diagrammatic illustration
similar to FIG. 2 showing the shank strip after it has been
activated and curing and illustrating the effect achieved by
employing a heat shrinkable film for the top strip of the
carrier sleeve; and
FIG. 26 is an illustration, similar to FIG. 24,
. 30 showing the shank strip having a still further modified cross-
':
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1 sectional shape, attached to the insole bottom in readiness
to be activated.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
' 5 FIG. 1 shows a segment of one embodiment of the
rope, indicated generally by the reference character 10, used
in the practice of the invention. The rope includes an
elongate outer carrier sheath or sleeve 12 which contains
a multiplicity of elongate fiber strands 14 embedded in a
fluid matrix 16 composed of a thermosetting resin and
catalyst which will not polymerize or crosslink under ambient
conditions over long shelf lives of for example three months
or more. The rope 10 is flexible and long lengths of it, for
example, hundreds of feet, may be wound on a reel to facili-
,, ,~, ~.
15 tate manufacture of the rope, storage, handling and subse-:'1
quent use. The ends of the reeled-up rope are preferably
sealed. Depending on the technique employed for fabricating
the rope, the sleeve 12 may have a longitudinal lapped seam
18. .
The rope 10 may be of somewhat flat, ribbon-like
shape being of the order of from 3/32" to 3/8" thick and
approximately 3/8" to 1" wide. The rope preferably has a
i ",
! cross sectional area of from 0.03 to 0.38 square inches.
The matrix 16 in which the fiber strands 14 are
embedded is a thermosetting resin material in fluid or semi-
fluid form. Matrix resin material viscosities of from 150
centipoises to 1350 poises (as measured on a Brookfield vis-
cometer at 77 F RVF Spindle #7) are preferred. The matrix
resins can be hardened into cross-linked polymerized mate-
rials having hardness values of from 40 to 80 Barcol. Par-
.. . .
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1 ticularly suitable thermosetting resins useful in this inven-
tion are the unsaturated polyester resins which are the pro-
ducts of chemical condensation of organic glycols and organic
unsaturated dibasic acids produced hy esterification. The
polyesters are formed from glycols such as propylene glycol,
dipropane glycol, ethylene glycol, diethylene qlycol, neopentyl
glycol or combinations thereof reacted with dibasic acids such
as maleic acid. Other common additives to such polyester
resins may also be employed such as saturated acids and organic
products including phthalic anhydride, isophthalic acid,
adipic acid and others which are commonly used to control the
degree of unsaturation in the polyester which in turn controls
the cross-linking and physical properties of the finally
cured resin and the speed of curing possible.
Organic unsaturated monomers are used as solvents
for the polyesters and are reactive therewith in cross-linking
and polymer formation. These monomers are also useful to
adjust precured viscosity to within the range noted above.
Preferably styrene is the monomer of choice for use in the
present invention. However, monomers such as methyl metha-
crylate, diallyl phthalate, vinyl toluene and the like as
known in the art can be used. The monomers are mixed with
the polyesters preferably in amounts of from 30% to 65~ by
weight of the total resin mixture to achieve viscosities of
from 1350 poises to 150 centiposes allowing thorough incor-
por~tion of the fibers and desired flexibility of the final
rope.
The thermosetting resin mixture 16 can also have
incorporated therewith suitable promoters to assist the
catalyst in production of nascent oxygen, catalysts or catalyst
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1 mixtures to produce nascent oxygen, thixotropic agents where
necessary to preserve viscosity and other conventional addi-
tives.
Inhibitors can be used as known in the art to pre-
vent premature reactions. Such inhibitors include substitutedhydroquinones such as p-benzoquinone, p-tert-butylcatechol,
monomethyl ether, 2,6-di-t-butyl-p-cresol and others commonly
known in the art. These inhibitors are preferably used in
amount~ of from 0.0025% to 0.015% by weight of the resin mix-
ture and prolong shelf life of the product so that ease of - ~
handling and flexibility is maintained over periods up to six
months at ordinarily encountered room temperature conditions.
The catalysts used can be any of the known free
radical initiators or combinations thereof including the peroxides
such as 1,1 Di-t-butyl Peroxy-3,3,5 Trimethylcyclohexane,
l,l-Di(t-butylperoxy)cyclohexane, t-butyl-perbenzoate and
t-butyl peroctoate or mixtures of these catalyst and other
peroxides. Peroxy ketal materials such as 1, l-Bis (t-Butyl -~
Peroxy)Cyclohexane and the like are preferred with styrene
polyester syrups while t-butyl perbenzoate is preferred for
use with diallyl phthalate syrups.
The catalyst is preferably used in amounts of from
.5% to 5% by weight of the thermosetting resin mixture.
Suitable promoters as known in the art include
dimethyl aniline, cobalt naphanate in conventional 6% metallic
solution and other cobalt compounds normally used in amounts
of from .2~ to .6% by weight of the resin mixture. The pro-
moters are sometimes used to speed up catalyst oxygen libe-
ration. Promoters are not always necessary.
The above thermosetting materials are preferably
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1 of medium viscosity so that they can be incorporated in the
glass fibers or other fibers used as reinforcements. In some
cases it is possible to add a solvent to the materials prior
to and during mixture with the fibers to enhance proper coating
of the fibers after which the solvent is removed as by evapo-
ration prior to coating with the layer 12. In some cases, an
additional thixotropic agent can be added such as Cab-O-Sil
(a trademark for a fumed silicon dioxide produced by Cabot Corp.
of Boston, Mass., U.S.A.) from .5% to 4% by weight of the resin
mixture. It is preferred to adjust the viscosity by styrene-poly-
ester syrup ratios rather than use of thixotropic agents.
The thermosetting resin of the matrix can be other
thermosetting materials such as epoxies, phenolic resins,
silicone resins, urethanes and polyvinyls. However, each of
these resin systems can have properties which are not as
suitable for useage in the rope of the present invention as is
the polyester monomer mixtures of the preferred embodiments.
Conventional inert fillers, pigments and the like
can be added if desired.
The fibers are preferably glass fibers although
other supporting fibers can be used. The glass fibers give
substantial strength at low cost in small volume and thus are
highly preferred. For example, tensile strengths of more than
100,000 lbs/sq. in. can be easily obtained. The fibers pre-
25 ferably have diameters of from 0.001 inch to 0.015 inch.
Straight glass roving bundles with from 12 to 16 bundles
about a center axis are preferred for use. Each bundle has
approximately 60 individual strands therein with the resin
mix impregnated into the strands and composite resin impregnated
; 30 rope being in the order of from .200" to .375" in diameter.
~ 13
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1 Other fibers can be used as for example metal fibers, poly-
ester fibers and carbon fibers, although costs may be increased
and other properties suffer. Preferably the fibers are used --
in amounts of from 20% to 75% of the total rope weight, and
the fibers are completely embedded within the liquid resin
material used by known methods for resin-embodying glass fibers.
The sleeve covering 12 preferably has a thickness of
from .001" to .002" although it may have a thickness of from
.0005 to .005 inch or more. In this embodiment, the covering
is preferably a thermoplastic resin such as polyethylene resin
which has a melting point such that it will melt and fuse
with the thermosetting resin upon crosslinking and polymeri-
zation when the shank is formed in the method of this invention.
However, it is not necessary that the covering sleeve disappear
entirely since it can become a part of the finished product
substantially in the form originally in the rope. Other
thermoplastic oovering materials such as cellulose acetate,
cellulose butyrate, polyvinyl acetate and the like can be
used. In some cases, the coating or sleeve 12 can even be a
thermosetting material such as a rubber material or a thermo-
setting material such as a cross-linked polyester styrene
combination compatible with and bondable with the completed
shank stiffener. In all cases it is preferred that the sleeve
12 be impermeable to migration outwardly of the matrix and
prevent inward migration or passage of materials which would
adversely affect the shelf life of the stored matrix material.
In addition, it is preferred that the sleeve be such as to
allow penetration by ultraviolet light when the thermosetting
matrix is to be set by ultraviolet light and also allow
passage of heat to the core to initiate polymerization and
cross linking.
14
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1 The sleeve can in some cases be formed directly on
the rovings in the form of a skin. For example a resin wetted
roving rope can be sprayed with a mixture of polyester syrup
and a 2% Vicure-10 (trademark) photo-initiator produced by
Staffer Chemical of Edison, New Jersey, U.S.A. and im~ediately
treated with ultraviolet light to form a thin polyester skin. This
skin performs the function of sleeve 12 of a thermoplastic material.
In this embodiment the sleeve 12 is formed of a
thermoplastic material which melts at a temperature of from
175 to 275 and the matrix resin mixture cures and sets to a
hard material having a flexural strength from 17000 psi to
20000 psi (ASTM method 790) or higher within 5 to 10 minutes
after radiation exposure which produces a temperature of from
220F to 360F in the reaction mixture. Preferably the
thermosetting material is polymerizable and/or cross-linkable
to its final form without generating temperatures at the
margins or other portions of the shoe which are adhered with
thermoplastic adhesives, which temperatures are high enough `
to destroy the adherence of such thermoplastics.
FIGS. 2-7 show one manner in which a shank strip 20,
cut from the rope 10, may be applied to an insole bottom to
stiffen the shank region of the shoe assembly. As shown in
FIG. 2, the shoe assembly in this stage of manufacture in- ~;
cludes a last 22, an insole 24 on the last bottom and an upper
26 which has been stretched about the last 22 and has had its
margin 28 firmly secured to the margin of the insole. The
upper margin 28 may be attached to the insole margin by
thermoplastic adhesive as is a common practice in the art.
The shank strip 20 is cut from a reeled-up rope 10
to the desired length for the particular shoe, and typically,
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1 should be cut so that when it is placed, it will extend from
the ball region 30 heelwardly to the heel breast region 32.
In one method of applying the shank strip 20 to the shoe
assembly, the underside of the shank strip may be slit longi-
tudinally, as suggested at 34 in FIG. 4 to define a pair ofseparable flaps 36 at the underside of the shank strip 20.
The flaps may be spread apart as suggested by the arrows 38
and shown in FIG. 5, to expose the underside of the resinous
matrix 16. The matrix 16, although flexible, is quite tacky
and viscous and a film of it will adhere to the underside of
the flaps 36 as suggested at 40 in FIG. 5 and when pressed
against the insole, it spreads as shown in FIGS. 6 and 7.
The strip 20 is applied to the insole as suggested in FIG. 5
with the resinous matrix in contact with the surface of the
15 insole. The tackiness of the res'nous matrix 16 holds the
strip 20 in place. The strip 20 is pressed toward the in-
sole bottom fully along its length to insure that its con-
tour will correspond to that of the insole bottom. In this
regard, it should be noted that the sleeve is not tacky and
will not gum up the pressing tool. If desired, the ball and
heel ends 40, 42 may be pressed somewhat flatter against the
insole to define a feathered configuration at the ends of the
strip 20 in smooth engagement with the insole bottom. This
results in a reduced thickness at the ball and heel ends,
where less rigidity is required.
When the resin and catalyst of which the matrix 16
is composed are activated by heat, the strip 20 can be heated
in stages, including a pre-heating of the shank strip 20
after it is severed from the rope 10 but before it is applied
to the bottom of the shoe assembly. For example, hhe shank
. ,.
'
16
' '' :
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1 strip 20 may be heated to approximately 150 F (below the melt
temperature of the sleeve) and is applied to the bottom of the
insole in the preheated condition. After the shank strip 20
has been so applied, it is then exposed to additional heat to
raise its temperature to activate the resin and initiate
polymerization and/or cross-linking. By employing the pre-
heating step, the second heating step at the higher tempera-
ture level is relatively brief to insure that no other portion
of the shoe will become overheated. For example, the second
heating step requires exposure to the heat source for pre-
ferably no more than between two to five seconds. Alternatively,
the shank strip 20 may be applied to the insole bottom without
pre-heating and the heat applied to the shank strip is loca-
lized, as will be described, with the same effect. It should
be noted, however, that by employing a pre-heating stage which
does not require presence of the shoe assembly, a higher
production rate may be achieved and a large number of shank
strips can be pre-heated at the same time.
In some cases the sleeve 12 may be stripped from the
core at the point of application to the shoe assembly, either
just before or after it is placed on the shoe. For example,
in the shank strip shown in FIGS. 4-7, the slit sleeve 12
could be stripped away before the matrix is activated.
FIGS. 8 and 9 illustrate a preferred technique for
heating the shank strip 20 in place on the insole bottom and
includes a radiant heater 44 to which the underside of the
shoe assembly is exposed at the region of the shank strip 20. ;
The heater 44 includes a quartz infrared tube 46 and a direc-
tional or focusing type of reflector 48 arranged to direct
and confine the infrared radiation to the localized region
'
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1 of the shank strip 20. If desired, a supplemental shield 50
having an elongate opening 52 (suggested in phantom in FIGS.
8 and 9) may be disposed between the heater 44 and the shank
strip 20 to further insure localized heating. The thermoplas-
tic sleeve is preferably formed from a material which is sub-
stantially transparent to infrared radiation.
FIG. 10 shows an alternative method of placing the
shank strip 20 on the insole bottom. In this technique, the
shank strip is slit at its underside as suggested in FIG. 4
and is placed on the insole bottom without spreading the flaps
36. A light but firm pressure on the strip will cause some
of the resinous material to be forced through the slot and
between the underside of the sleeve 12 and the insole as
suggested by the layer 54 in FIG. 10.
FIGS. 11 and 12 show a further technique for applying
.,
the strip 20 to the insole bottom. In this technique, the
, underside of the strip (shown inverted in FIG. 11 for clarity)
is slit longitudinally along two spaced lines indicated at 56
and the portion 58 intermediate the slits 56 is peeled off
as suggested in FIG. 11. This exposes a substantial width
of the matrix 16 which may be placed against the insole bottom ~ -
as suggested in FIG. 12.
It should be noted that in each of the foregoing
embodiments Of the invention, the resinous matrix 16 of the
shank strip 20 is in contact with the insole along the length
of the strip which insures a firm, intimate and inseparable
bond with the insole when the material has fully cured. Pre-
ferably the attachment contact is continuous along the under-
side of the strip, however in some cases spaced points of
attachment suffice to provide sufficient bonding and reinforce-
ment.
18
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1 FIG. 13 shows still another technique for effecting
direct contact of the resinous matrix with the insole bottom.
Here, the underside, insole-engaging surface of the sleeve 12
is provided with a plurality of generally transversely extending,
longitudinally spaced slits 60 through which the resinous
; matrix may be extruded against the insole bottom under a light
pressure. This results in the configuration shownin FIG. 14.
FIG. 15 shows yet another technique in which a multi-
plicity of holes 62 are punched or otherwise formed in the
under-surface of the sleeve 12 which, when applied to the in-
sole bottom will permit the resinous matrix to flow against
the insole bottom.
It should be noted that while the foregoing techniques
for applying the shank strip to the insole bottom, in which
the insole-engaging undersurface of the sleeve 12 is slit or
perforated may not be essential in order to practice the inven-
tion, depending on the nature and types of thermosetting resin
and thermoplastic sleeve employed. For example, FIG. 17 shows
an unperforated, unslit shank strip applied directly to the
bottom of the last. A light film of adhesive may be applied to
the underside of the sleeve 12 merely to aid in holding the
strip 20 in place on the insole. When the strip is activated,
for example, at a temperature of 200 F., it will polymerize ~-
in an exothermic reaction which raises the localized heat of the
strip 20 to, for example 350 F., well above the melting tem-
perature of the thermoplastic sleeve 12. This causes the -
thermoplastic sleeve 12 to melt and fuse with the matrix and
to become cross-linked in a single, unitary and integral mass
which is firmly bonded to the insole bottom. As an alternative ~ -
to preliminarily retaining the shank strip 20 by an adhesive
19
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1 coating, two or three small, longitudinally spaced holes may
be punched in the underside of the sleeve 12 to expose a
minute, but sufficient amount of tackty matrix 16 to hold the
shank strip 20 in place.
In some cases adhesive can be placed on the strip
or shoe part prior to placement of the strip so as to provide
a bond between the two while the matrix material acts only to
provide stiffening.
The foregoing method of applying the shank strip
mzy be modified as suggested in FIGS. 18 and 19 to facilitate
flattening out of the ball and heel ends 40, 42 of the shank
strip 20. Here, each of the ends of the shank strip is slit
at its transverse sides as shown in 64 in FIG. 18 so that when
the end portions are pressed downwardly against the insole
some of the matrix resin znd reinforcement glass rovings can
~ sque~eze transversely out of the slots 64 as suggested in FIG.
.. 19.
FIG. 20 shows, diagrammatically, the manner in which
the rope 10 may be made. The fiberglass rovings are delivered
from supply reels, indicated generally at 66. The fiberglass
rovings are directed through the resin-catalyst bath 68 by a
doffing bar and roller arrangement 70 and then through a pair
of stripping rolls 72 to squeeze excess resinous material from
the rovings. The rovings are advanced by drawing rolls 74 and
then enter a continuous folding and sealing device 76 which
also receives a strip of thermoplastic sleeve material which
may be supplied from a roll 78 thereof. Folder/sealer 76
encases the impregnated fiberglass strands with the sleeve
material and seals the seam 18 to form the rope 10. The rope
10 is drawn from the folder/sealer 76 by another pair of
10A92/707
AZs/ams
78
1064ZS;~
1 drawing rolls 78' and then pass through an end cut and sealing
device 80 which periodically cuts the rope and effects a seal
on both sides of the cut to end one reel length of rope and
begin the next reel length. A reeling device 82 winds the
rope onto a reel for shipping or storage and in a form ready
for use.
The following examples are illustrative of particular
formulations for practicing the invention. However, these
examples are non-limiting of the invention as many formulations
and procedures can be used as described in this specification.
"
EXANPLE 1
-~ A rope 10 is formed with a 0.001 inch thick film or
sleeve 12 of low density polyethylene having a melting point of
about 235F with the rope being oval in cross section and having a
cross sectional area of .072 sq. in. The matrix is formed of
glass fiber rovings in 16 parallel bundles having a weight of ~;
.0015 to .0018 pounds per linear inch of rope. The resin
material is a polyester syrup formed of maleic acid and a polyol
sold by Reichold Chemical Co. of White Plains, New York,U.S.A.
under Number 31.000 and containing 30% to 40% by weight of
styrene monomer and an inhibitor. The viscosity of the syrup
is 750-1050 centipoises. One hundred grams of the syrup are
admixed with .5 grams of an accelerator, Reichold Number DMA-0182
25 which is 100~ dimethyl aniline and 2.0 grams of a catalyst
which is a peroxy ketal produced by Lucidol Division of Pennwalt
Corp., Buffalo, New York, U.S.A. under the trademark Lupersol
- 331-80B. The material is admixed with the glass rovings and
then covered with a .001 inch thick polyethylene film 12 pro-
duced by Exxon Chemical Company, Clark, New Jersey, U.S.A.
B
.... ... . . . .
, . . . ~ . .
. . ~ . .
. ..
,
. - i
. .. . .
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1 The film 12 is folded over the impregnated matrix with a longi-
tudinally extending seam fused together as at 18.
An 800 foot long rope is formed which is easily
bendable by hand and is coiled. The coil is used by cutting
lengths of from 4 inches to 6 inches applying to a shoe as
~. shown in FIG. 2 after first slitting along the length thereof
; and pressing at a pressure of from 4 oz. to 6 oz. A heater
, such as 44 is used to apply a radiation energy to produce an
absorbed and exothermic temperature of 220 to 360 F for 4
preheat sec. and 4 sec. final heat when the shank is on the
` shoe to cross-link the material and form a final shank adhered
to the insole with a flexural strength of 17,000 psi.
''
EXAMPLE 2
In this Example, Example 1 is repeated except that
the dimethyl aniline is eliminated. Substantially similar re-
sults are obtained although in some cases slightly longer
final heating times are necessary in order to obtain the de-
sired flexural strength.
' 20
EXAMPLE 3
Example 1 is repeated except that the catalyst is
used in an amount of 1 gram and is t-butyl perbenzoate. A
desirable adherent shoe shank is obtained.
EXAMPLE 4
Example 1 is repeated except that the resin material
of that Example formed of maleic acid and a polyol is not used
and in its place a polyester syrup formed of maleic acid and
a polyol sold by Reichold Chemical Co. of White Plains, New
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1 York, U.S.A. under Number 31,402 and containing 40% by weight
of diallyl pl~halate monomer and an inhibitor is used in its
place. The viscosity of the syrup is 4000-5000 centipoise
(Brookfield-77DF). One hundred grams of this syrup are ad-
mixed with 20 grams of diallyl phthalate monomer to bring the
syrup up to 50% by total weight of diallyl phthalate. A mix-
ture of catalysts are used comprising 0.5 grams to t-butyl-
peroctoate and 1.5 grams of t-~utyl perbenzoate in place of
the peroxy ketal noted in Example 1.
In this Example, the shank is split and applied as
shown in FIGS. 5-7.
- The heater 44 is used to apply radiant energy to
produce an absorbed exothermic temperature of from 250 to
360F for 8 preheat seconds and 4 final heat seconds.
That is, the strip is preheated before application to the shoe
for 8 seconds and heated on the shoe for 4 seconds. The final ~ -
. shank is adhered to the insole and has a flexural strength ~ -
, . ~ , - .
~ exceeding 18000 psi. ~ .., , ~ . ~
EXAMPLE 5
. :
Example 1 is repeated except that the resin material
is a polyester syrup sold by American Cyanamid of Wellingford,
Connecticut, U.S.A. as Laminaa (trademark) polyester resin 4202 ;
containing 30 to 40% diallyi phthalate monomer. The viscosity of
'h 25 the s~rup is 1350 poise (Brookfield Model RVF Spindle No. 7, 10
- rpm 77) and is temporarily reduced during impregnation into
the glass rovings by the addition of a solvent. One hundred
grams of this polyester syrup is admixed with 40 grams of
trichloroethylene and 1.0 grams of a peroxy ester catalyst,
i.e. t-butyl perbenzoate. This mixture is impregnated into
.. .
' :
.
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1 the glass roving bundles at a very low wet viscosity to form
a glass resin rope. The triohloroethylene is then removed by
heating the rope in an evaporation chamber at a temperature
between 150 and 180 F. The result is a very dry rope which
can be covered with the polyethylene and then applied as pre-
viously described.
EXAMPLE 6
Example 1 is repeated except that the rope formed
is cut to remove a 6 inch length which is then applied to
the insole. Here the rope is perforated and applied as des-
cribed in FIG. 12. A structurally strong final shank is ob-
tained.
EXAMPLE 7
A rope 10 is formed with a 0.001 inch thick coating
12 of polyethylene having a melting point of 240 F with a
rope being oval in cross section and having a cross sectional
area of .072 square inches.
The matrix is first formed of glass fiber rovings
in 12 parallel bundles having a weight of 0.0015 pounds per
linear inch of rope. The resin material is a polyester syrup
formed of maleic acid and a polyol sold by Reichold Chemical Co.
of White Plains, New York under Number 90-569 containing 30-40%
by weight of styrene monomer, an inhibitor and a benzoin ether -
photosensitizer. The viscosity of the resin syrup is 400-500
Centipoise 77 F Brookfield. One hundred grams of the syrup
is admised with 20 grams of styrene monomer to reduce the final
viscosity. The material is admixed with the glass rovings and
the polyethylene film applied as described in Example 1.
24
" "....
" ' '' ''' '' ' '
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1 A 5 inch length of polyethylene sleeved rope is
flattened to 0.090 inches in thickness and placed on the shank
area of a shoe insole. Two inches away from the rope is
~` placed a 5 kilowatt input ultraviolet radiation unit. After
S 5 seconds, the radiation cycle produces a stiff shank piece
which when cooled to room temperature after reaching an exo-
thermic temperature of 275 F, provides a structurally strong
adherent shoe shank.
In other examples of this invention, the glass fiber
rovings can be varied in number and weight to vary the strength
of the final shoe shank. In some cases fillers such as 1/4
inch long chopped glass fibers can be added to again increase
structural strength. In all cases it is preferred that the
polyesters are formulated to be 100~ reactive preferably with
small quantities of peroxide catalyst activating the unsatu- `
.
rated liquid thermosetting resins to form tough sol~d plastics
at elevated temperatures with no unwanted by-products formed.
While specific embodiments of the present invention
have been shown and described, many variations are possible.
20 For example, the term "rope" or "article" as used herein can
refer to preformed lengths of rope conforming to the size of
a shank to be used. For example, the rope can be cut in
lengths of 3 inches, 4 inches and 5 inches and used of varying
sized shoes when needed rather than stocked as a coil. The
lengths can be sealed at either end as by an end cap of thermo-
plastic material formed thereover just as the skin coating or
sleeve 12 is formed. The temperature used to heat the matrix
in order to activate it is preferably in the range of from
225 to 275 F. although ~ther temperatures can be used. In
the case of ultraviolet radiation, no elevated activating tem-
perature i8 employed.
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1 FIGS. 21-26 show another embodiment of the carrier
sleeve in which the sleeve is formed from a pair of longitu-
dinal strips joined at their longitudinal edges to define lon-
gitudinally extending margins. FIG. 21 shows a segment of the
rope from which lengths may be severed. The rope includes an
envelope in the form of an elongate outer carrier sheath or
sleeve indicated generally at 110 which contains the multipli-
city of elongate fiber strands 112 embedded in the fluid
matrix 114 composed of a thermosetting resin and catalyst
which will not polymerize or cross link under ambient conditions
over long shelf lives of, for example, three months or more.
The ends of the reel-up rope are preferably sealed. The
various resins and catalyst formulations and fiber reinforce-
ments which may be used in the matrix are the same described
above.
In accordance with this embodiment, the carrier
sleeve 110 is formed from a pair of sheets or strips of mate-
rial, including what is defined as an upper or first strip 116
and a lower or second strip 118, the lower strip being intended
to be applied directly to the element to be stiffened, such
as an insole bottom. The upper and lower strips 116, 118 may
be formed to define their carrier sleeve configuration, encasing
the matrix and fiberglass strands, by commercially available
sealing equipment which can join the longitudinally extending
margins 120, 122 of the strips 116, 118. The margins 120, 122
may be joined by any of a variety of well known techniques
such as interposing an appropriate adhesive between the mar-
ginal edges and/or heat sealing. Preferably, the margins are
relatively wide and by way of example, in a strip which is
1 1/2" wide overall, the width of the matrix would be approxi-
lOA92/707
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1 mately 3/4" and each of the margins would be approximately
3/8". In a preferred configuration of the invention, for use
as a shank stiffener, the shank strip may be generally flat,
having a height of approximately .080". In most cases, the
rope has a width of from 1/2 to 2 inches, with each margin
having a width of from 1/8 to 1/2 inch, the matrix having a
width of 1/4 to 1 inch and a thickness of from 0.03 to 0.38
inch. Lenghts of from a few inches or longer can be hardened
into completed shank strips.
The lower, insole-engaging strip 118 may be formed
from a relatively low melt temperature thermoplastic such as
; polyethylene having a melting point such that it will metl and
~' fuse with the thermosetting resin upon cross linking and poly-
:.;
~ merization. For example, the polyethylene may melt between
~ .
~ 15 175 F to 275 F. Other materials may be employed for the
: lower strip 118 such as cellulose acetate, cellulose buyrate,
polyvinyl acetate or the like. In some instances, the lower
. ~ .
strip 118 could even be a thermosetting material such as a
` rubber material or a cross-linked polyester-styrene combination
compatible and bondable with the matrix material of the finished
shank stiffener. In all cases, it is preferable that the
lower, as well as the upper strip, be impermeable to migration
outwardly of the matrix and prevent inward migration or pas-
sage of materials which might adversely affect the shelf life
of the stored matrix material. When the lower strip does not
metl or disperse during the hardening of the matrix, it can
be provided with perforations during or slightly before hardening
to provide for adhesion of the matrix to the shoe bottom. In
some cases, a supplementary adhesive can be used to bond to
the shoe bottom.
.... . .
-
lOA92/707
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1 The upper strip 116 is formed from a thin sheet of
material which is transparent to the radiant energy or other
external stimulus to be used to activate the matrix. In accor-
dance with an important feature of this embodiment of the
invention, the material from which the upper strip 116 is
formed will retain at least some of its tensile properties and
will not melt or otherwise adversely deteriorate during acti-
vation of the matrix, at least until the matrix has cured
sufficiently to its final shape. Thus, where the matrix is
activatable by heat (as from an infrared heater) and where
the matrix generates an exothermal reaction, the upper strip
116 should be temperature resistant at least to the extent
that it will not deteriorate from the effect of such exo-
thermal temperatures, at least until the reaction has been
substantially completed to an extent in which the shape and
size of the resin has become fixed. By way of example, where
temperatures of the order of 400-420 F may be reached from
the combined effect of the exothermal reaction and the infra-
red heater, the material of the upper strip should be selected
20 to be capable of maintaining its ~trength and integrity up to
that level. It may be noted that usually the thermoset matrix
will cure to its final shape before the maximum temperature
has been reached, and in that case, the upper strip may be
~ permitted to melt or otherwise deteriorate at that temperature
; 25 level. By way of example, the upper strip 116 may be made
from a number of polyester films, such as Mylar, a trademark
product of polyethylene terephthalate sold by E. I. DuPont
de Nemours & Co., Wilmington, Delaware, U.S.A. (melt tempera-
ture of about 420 F) and may be of the order of .001" thick.
Top strip materials are preferably shrink materials ~ -
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1 such as axially or biaxially oriented polyethylene terephtha-
late (Mylar). Such materials are preferably selected so that
they shrink 5% to 35~ in width in 3 to 5 seconds at temperatures
of 300 F or the temperature of the shank strips during
hardening. Such films have good ten~ile strength as for exam-
ple resistance to 25000 p$i at 70 C to 300D C. Surprisingly,
very little force or resistance to matrix expansion need be
provided by the top strip to prevent unwanted expan~ion of the
matrix. Other materials which can be used for the top strip
include, but are not limited to, other polyesters such as
polybutylene terephthalate, polyethylene nylon, polypropylene,
polybuylene and copolymers of the above and other plastics.
The thickness ranges of the top and bottom skins can
vary depending on the particular shanks to be formed and par-
ticular materials used. Preferably, in order to minimize
expense and maximize desirable handling and storage properties
the top and bottom skins or strips each may have a thickness
of the order of 0.0005 inches and preferably in the range of
.0005 to 0.0025 inch.
The margins of the skins may be bonded to each
other in a heat sealing process. When the top skin is Mylar
and the bottom skin polyethylene, it is preferred to coat the
surface of the polyethylene with a thin film of ethyl vinyl
acetate (EVA) to promote the heat sealing process without
causing deterioration of the polyethylene. Alternatively,
polyethylene mixed with 3%-8% EVA may be employed. Such a
polyethylene-EVA composition is available from St. Regis Paper Co.
The shoe bottom material to which the shank strips -~?
are adhered can be of any cor,ventional shoe insole material
as, for example, fibrous board, leather or the like.
29
; ,,, . . - ,
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1 As shown in FIG. 22, a shank strip of desired length,
typically four to six inches in length is cut from the rope-
like supply and is placed on the bottom of the insole, with
the lower strip 118 in engagement with the insole 124. The
wide margins of the carrier sleeve 110 provide a convenient,
mess-free means by which the carrier sleeve can be held in
place, for example, by staples 126. The shank strip then is
exposed to the external stimulus, as previously described to
activate the thermosetting matrix. As described in the fore-
going example, the applied heat and the exothermal reactionof the matrix during curing generate progressively increasing
` temperatures up to approximately 400 F to 420 F, sufficiently
high to melt the lower strip 116 of the carrier sleeve 110
and cause cross linking and merging of the lower strip 116
and matrix into a single mass which adheres to the insole
bottom. The matrix usually will assume its final shape before
the maximum temperature has been reached. The upper strip
116 or film, which will retain its mechanical properties
(such as tensile strength) and has a melt temperature at or
slightly higher than that generated during curing, retains its
size and form to confine the thermosetting material between it
and the insole bottom as the reaction proceeds. Thus, if the
matrix tends to expand during curing, it will be confined by
the upper strip 116 to limit the height as well as general
cross sectional shape of the stiffener which will result. In -~
this regard~ it should be noted that the forces of expansion
which may tend to be developed by the matrix are relatively
light and can be sufficiently resisted by the upper strip 116
to assure that the resin will not expand beyond a desired
height and configuration. Although in some instances, it has
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1 been found that the upper strip 116 may deteriorate somewhat
and merge with the matrix material in the regions in which
it is in contact with the matrix, the strip 116 does reqist
- deterioration sufficiently to confîne any unwanted expansion of
, . .
the matrix during the hardening or curing step. This occurs
even though in some cases the top strip i8 formed of a mate-
rial with a low softening point and which may become dis~on-
tinuous after the curing step. The marginal portion~ of the
: .
strip 116 may only curl or buckle. The marginal strips are
easily detachable from the shoe bottom and may be stripped off
. if desired. It might be noted that in some instances, such
~ as with welt shoes, there may be no particular advantage ob-
! ~ tained by stripping the remaining margins of the carrier sleeve
110 because that region subsequently will be filled with a -~
..
; ~ 15 filler material as is well known to those skilled in the art -
. .~ . and under such circumstances the margins may remain.
The embodiment of the shank strip illustrated in
FIG. 21 has a cross section in which the marginsof each of the
upper and lower strips 116, 118 are formed at a level which is
approximately intermediate the thickness of the central por-
~¦ tion of the strip. It may be noted that in the shank strip
described above, having a polyester (Mylar) top strip 116 and
a polyethylene lower strip may be more like that suggested in
3 FIG. 23, in which the upper strip 116 i8 generally flat and
the lower strip 118 is somewhat channel-shaped to receive and
~ accommodate the matrix. This configuration may result, depen-
;! ding on the type of rope manufacturing equipment employed. .
1 It should be noted that the polyethylene typically will be
more easily stretched during the manufacturing procedure than
the polyester top strip, which accounts for the cross se~tional
. .
31
.' ':
: . :
~': ' , ~, ' .
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1 shape shown in FIG. 23. FIG. 24 illustrates the manner in
which the strip shown in FIG. 23 is applied to the bottom of
the insole. Although there may be some voids, as suggested
(in exaggeration) at 128, when the shank strip is activated
i 5 and the lower polyethylene strip 118 merges and fuses with
the resin, the expansion which usually takes place will cause
the matrix to substantially fill any voids. FIG. 25 illus-
trates, somewhat diagrammatically, the cross-sectional con-
figuration of the stiffener after the lower strip has been
merged and fused into the matrix, with the stiffener in its
final shape but before the upper strip 116 has deteriorated.
It should be noted that the somewhat diagrammatic
illustrations of FIGS. 24 and 25 relate to the upper strip
116 which will shrink in response to the heat applied and/or
generated in the reaction. The upper strip 116 is shown in
its shrunk configuration in solid in FIG. 25. For example,
the width of the strip as shown in FIG. 25 and as measured
widthwise along its surface and from staple 126 to staple 126,
may be of the order of 10-15% less than before activation,
as shown in FIG. 24. It also should be noted that although
the surface-measured width of the top strip 116 has been re-
duced, the height of the hardened shank is greater than the
original height of the unactivated shank strip. By way of
example, with an uncured shank strip as shown in FIG. 24,
the height of the strip initially may be of the o~der of .090 ~-~
inches in thickness (height) whereas after having been cured,
the height of the hardened strip, shown in FIG. 25, may be
of the order of .35 inches in height, an increase of approxi-
mately 50% in height. It also should be noted that the cross
section of the hardened shank is generally convex (along its
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1 upper surface) as compared to the approximately rectangular
configuration of the matrix before curing. This is believed
to result from early deterioration or melting of the lower
strip 118 which permits the resinous matrix to flow freely
within the region defi~ed between the insole and the top strip.
The resin tends to fill out this volume which results in the
generally convex shape of the hardened shank and in which
the lateral edges of the shank taper and gradually slope
toward the surface of the insole bottom. As the bottom strip
118 deteriorates, the top strip 116 no longer is constrained
to an approximately rectangular configuration and can assume
the more convex shape shown in FIG. 25 under the influence
of resin flow. Moreover, as the upper strip 116 shrinks, that
tends to apply a light pressure to the resin to cause it to
flow somewhat laterally outwardly which promote forming of
the gradually tapering side edges.
As mentioned above, the principles of this embodi-
ment of the invention may be employed with an upper strip 116 f
which will have little or no tendency to shrink yet which
will still retain its dimensional characteristics at least
until the resin has cured to a substantially final shape.
This is suggested somewhat diagrammatically in FIG. 25 in
which the phantom line 117 represents the comparative configu-
ration of the cured shank when a non-shrinkable upper strip
116 is employea. As can be seen, the height of the shank
will be greater than that which results when the shrinkable
top strip 116 is employed and, for example, may be of the
order of .150 inches in height. Whether a shrinkable or a
non-shrinkable top strip is employed, it is important that the
material from which the top strip is formed be selected from
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1 one which will not deteriorate during curing to an extent
which would permit expansion of the resin beyond predetermined
limits. By way of example, in the absence of confinement of
the resin as described herein, there have been instances in
which the height of the finally formed shank increased about
three-fold (e.g. from .09 inches initial height to approxi-
mately .30 inches height). Such a magnitude of increased
height is undesirable because it usually is accompanied by
formation of relatively large gas bubbles which might effect
the strength of the shank and also because a shank of that
height often will interfere with subsequent shoe making pro-
cedures, such as attachment of the outsole, as will be appre-
ciated by those of skill in the shoe art.
FIG. 26 illustrates a shank strip having a substan-
lS tially flat lower strip 118 and a channel-shaped upper strip
116. The resulting product is substantially the same as that
illustrated in FIG. 25.
I have found that in most instances, it is desirable
to utilize a top strip 116 which will shrink during reaction
of the matrix, for example, in response to elevated tempera-
tures from the exothermic reaction or from the combination ofexothermal and applied heat. Use of a shrinkable top strip
thus provides control over the height and cross section of
the region confined by the top strip. In addition to controlling
the height and cross-sectional shape of the resulting stiffener,
the use of an upper strip which will shrink during the activa-
tion or curing procedure also applies a light compressive force `
to the resin which minimizes any tendency for large bubbles
to form within the resinous matrix, which might reduce the
strength of the stiffener. Still another advantage which re-
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1 sults from using a top strip which will shrink, isthat theresulting stiffener is relatively smooth and is free of sig-
nificant bumps, wrinkles, ripples or other irregularities
which might be undesirable. The shrinkable top strip material
may be either axially or biaxially oriented and a number of
such materials are available. I have found that a Mylar
.
polyester film which is biaxially oriented provides good
results.
In a specific example of forming a hardened completed
shank strip in accordance with this embodiment of the inven-
tion, upper strip 116 is 0.0005 inch thick Mylar type M 24
..::
with a heat shrink of 20% and lower strip 118 is 0.001 inch
thick low density polyethylene. The matrix is a polyester
syrup formed of maleic acid and a polyol sold by Reichold
Chemical Co., of White Plains, New York, U.S.A. under Number
31.402 and containing 40% by weight of diallyl phthalate
monomers. The viscosity of the syrup is 4000-6000 centipoise
(Brookfield -77 F), one hundred grams of this syrup is mixed
with 20 grams of diallyl phthalate monomer to bring the
... .
syrup to 50% total weight of diallyl phthalate 2% by weight of
the æyrup of t-butyl perbenzoate is incorporated as a catalyst.
The saturated glass rovings are formed in sixteen parallel
bundles having a weight of 0.0015 to 0.0018 pounds per linear
inch of rope. The rope formed is as in FIG. 21 with each
margin having a width of 3/8" and the matrix contained in a -
center sleeve having a width of 9/16" for a total side to side
dimension of 15/16"~and a matrix thickness of about 0.09 inch.
The rope is cut to form a four inch long shank strip which is
stapled to a shoe as shown in FIG. 22. The shank is then ex- -
posed to an infrared line heater in the form a six inch long
.
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10A92/707
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1 lamp positioned to give a 9/16" wide beam. After 6 to 8 seconds
of exposure the shank is hardened in its final form after first
reaching a top surface temperature of 320 F to 420 F. The
resulting shank is adhered to the shoe bottom and its matrix
has been re-shaped and has expanded slightly over its original
thickness.
The matrix resin materials preferably have storage
viscosities, and can be hardened to thermoset materials having
hardness values sufficient to act as excellent shoe shanks,
as described. A variety of thermosetting materials can be
used with fillers, pigments and catalysts as described. The
resin materials have long storage lives of three months or
more at standard room temperature.
The reinforcing fibers of the matrix are preferably
glass fibers having diameters of from 0.0001 to 0.015 inch
;- formed in roving bundles with from twelve to sixteen bundles
about a center axis. Other reinforcement fibers such as
metal, polyester, carbon and the like can be used. Preferably,
, the fibers are used in amounts of from 20 to 75% of the total
rope weight and are completely embedded in the thermosetting
material.
The thermosetting matrix material can be activatable
by an appropriate external stimulus. Preferably, radiant
energy is used in the form of infrared energy as from a
tungsten-quartz lamp with a wavelength of from 4000 to 40000
- angstroms. The matrix can be cured or thermoset to hardened
form by other means as for example R.F. energy, electric or
other heaters, ultraviolet and the like depending on the
particular matrix used.
From the foregoing, it will be appreciated that the
36
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lOA92/707
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1 sleeve construction of this embodiment provides a number of
advantages, particularly with respect to control over the
height and cross sectional shape of the stiffener as well as
with respect to the handling of the shank strip. These advan-
tages are achieved by utili~ing an upper strip which is formedfrom a material which will not deteriorate (i.e. will main-
tain its strength, mechanical Rroperties and pysical charac-
teristics) at least to the extent necessary to control the
shape of the shank at least until the shank strip has set to
its final shape.
It should be understood, however, that the foregoing
description of the invention is intended merely to be illus-
trative thereof and that other modifications and embodiments
may be apparent to those skilled in the art without departing
from its spirit.
Having thus described the invention, what we desire
to claim and secure by Letters Patent is:
,
,
