U.S. patent number 3,906,570 [Application Number 05/473,273] was granted by the patent office on 1975-09-23 for method of making an insole.
This patent grant is currently assigned to USM Corporation. Invention is credited to Howard B. Revill.
United States Patent |
3,906,570 |
Revill |
September 23, 1975 |
Method of making an insole
Abstract
Method of making insole of non-woven bonded fiber sheet material
including a shank portion of greater stiffness and density than the
forward portion in which a through layer of non-woven fiber sheet
including a heat-softenable binder is associated with one or more
layers of non-woven fiber sheet including binder in the heel and
shank or waist portion of the insole and the layers in the heel and
shank or waist portion are consolidated by heat and pressure to a
unitary board-like state in the heel and shank region. The insole
including the heel and shank region may be given a contour
approximating the contour of a bottom of a foot in a pressing
operation and may also incorporate a layer of stiff plastic sheet
material.
Inventors: |
Revill; Howard B. (Oadby,
EN) |
Assignee: |
USM Corporation (Boston,
MA)
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Family
ID: |
26993290 |
Appl.
No.: |
05/473,273 |
Filed: |
May 24, 1974 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
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342999 |
Mar 20, 1973 |
3835558 |
Sep 17, 1974 |
|
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Current U.S.
Class: |
12/146B |
Current CPC
Class: |
A43B
7/141 (20130101); A43B 13/38 (20130101); B32B
1/00 (20130101); B32B 5/28 (20130101); A43B
13/41 (20130101); B32B 5/022 (20130101); B32B
7/02 (20130101); B32B 5/26 (20130101); B32B
2437/02 (20130101); B32B 2262/0261 (20130101); B32B
2262/04 (20130101) |
Current International
Class: |
A43B
13/41 (20060101); A43B 13/38 (20060101); B32B
5/22 (20060101); B32B 5/28 (20060101); A43D
000/00 () |
Field of
Search: |
;12/146R,146B |
References Cited
[Referenced By]
U.S. Patent Documents
Other References
Crispin-Progress Edition; Section III--Processes & Methods;
February 1937; page 33..
|
Primary Examiner: Lawson; Patrick D.
Attorney, Agent or Firm: Pollard; Benjamin C. White; Vincent
A. Megley; Richard B.
Parent Case Text
This is a division of application Ser. No. 342,999, filed Mar. 20,
1973, now U.S. Pat. No. 3,835,558 dated Sept. 17, 1974.
Claims
Having thus described our invention what we claim as new and desire
to secure as Letters Patent of the United States is:
1. The method of making an insole comprising forming an assembly in
face to face relation of a through layer of non-woven bonded fiber
comprising a thermoplastic bonding agent having a softening point
below the melting point of the fiber of said layers and above the
temperatures to which said insole will be subjected in use and
having an outline shape corresponding to that of the insole and at
least one short layer or a non-woven bonded fiber having an outline
shape corresponding with or lying within the outline shape of a
rear portion of a through layer and subjecting the assembly to heat
and pressure to bond said through and short layers together through
the action of said bonding agent and to densify portions of said
assembly comprising both through and short layers so that said
portions have greater density and rigidity than portions not
comprising both through and short layers.
2. The method of making an insole as defined in claim 1 in which
said assembly is subjected to heat and pressure between heated
platens.
3. The method of making an insole as defined in claim 2 in which
said platens are shaped to impart to the insole a contour
corresponding approximately to a bottom of a foot.
4. The method of making an insole as defined in claim 1 in which
said assembly is subjected to heat and pressure between platens at
least one of the platens including a resilient surface having an
electrode embedded therein and in which heat to bond said layers
together and to densify portions of the assembly are generated by
establishing a high frequency field from said electrode to heat the
bonded fiber.
5. The method of making an insole as defined in claim 3 in which
said platens are shaped to impart to the insole a contour
corresponding approximately to a bottom of a foot.
6. The method of making an insole as defined in claim 1 in which a
layer of stiff resin material is disposed in the region of the heel
seat of the insole portion of the non-woven bonded fiber material
in said assembly and is joined to a bonded fiber layer by said heat
and pressure to provide a region in which heel attaching nails may
be driven.
7. The method of making an insole as defined in claim 1 in which a
shank stiffener member is disposed in the waist portion of said
assembly and is embedded in and bonded to a non-woven bonded fiber
layer by said heat and pressure.
8. The method of making an insole as defined in claim 7 in which
said shank stiffener is coated with a thermoplastic resin prior to
assembly with said layers of non-woven bonded fiber.
Description
FIELD OF THE INVENTION
This invention relates to improvements in methods of making
materials for use in the manufacture for shoes.
BACKGROUND OF THE INVENTION
Known insoles for incorporation in a shoe include those having a
forepart which is flexible to permit the shoe to bend as a wearer
walks and a more rigid heel seat and waist portion which gives
strength to the shoe in the heel seat and waist region thereof and
to which the heel of a shoe is commonly attached using suitable
fastening members, for example nails or staples. The forepart
portion of such insoles comprises a suitable flexible insoling
material, for example water laid fibrous sheet material bonded with
natural or synthetic rubber. The heel seat and waist portion of
such an insole comprises a more rigid fiberboard, commonly known as
shankboard. Insoles of this type may be cut from a composite board
made by sticking together a rectangular piece of flexible forepart
maaterial and shankboard; an edge portion of each piece of board is
skived, thus giving a tapered edge portion, and suitable adhesive
is applied to the skived edge portion of each material, the skived
edge portions are then brought into contact and the adhesive
thereon bonds the two pieces together. When the adhesive has set,
insoles are cut from the so-formed composite board. The insoles cut
from the board have a lap joint in the region of the ball of the
foot. After the insoles have been cut out it is a known practice to
impart a shape corresponding approximately to the contour of the
bottom of a foot to the insoles by subjecting them to pressure
applied by dies having a suitable shape in a suitable machine.
SUMMARY OF THE INVENTION
One of the various objects of the present invention is to provide
an improved method of manufacturing a unitary shoe insole having a
stiff rear portion and a flexible forepart.
To this end and in accordance with a feature of the preseent
invention a unitary shoe insole is formed by assembling through and
partial layers of non-woven bonded fiber and combining them with a
unitary insole by heat and pressure.
BRIEF DESCRIPTION OF DRAWINGS
FIG. 1 is a showing of the completed insole.
FIG. 2 is an exploded view of the insole and pressing means.
FIG. 3 is a cross-section of the insole taken on line III--III of
FIG. 1.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
An insole 10 according to the present invention is a non-woven
bonded fiber sheet having an outline shape for incorporation in
footwear and is constructed to have a rear portion 12 of greater
density and rigidity than the fore part 14. The insole may be
formed from one or more through layers 16 having an outline shape
corresponding to that of the insole and one or more short layers 18
bonded to a rear portion 20 of the through layer. Each of the
through layers is a non-woven bonded fiber batt which may be made
by first forming an intermediate batt by garnetting, cross-laying
and needling fibers and then introducing a binder into this
intermediate batt. Any of the usual fibers employed in making
non-woven fabrics may be used including nylon, rayon, polyester and
cotton and mixtures of these. Suitable binders include heat
softenable resinous materials such as the vinyl polymer and
copolymer resins, polystyrene, polyacrylates and methacrylates,
polymers and copolymers of isobutylic and butadiene, natural resins
and mixtures of these. The melting point of these resinous
materials must be high enough not to soften in use but low enough
to be softened for bonding together of layers in the press. The
binder may be applied as an aqueous emulsion or as a volatile
organic solvent solution or in powder form. The amount of binder is
not particularly critical and an amount of the order of about equal
parts by weight of fibers and binder in the non-woven layer has
been found useful. At least one short layer of each illustrative
insole also consists of a similar non-woven bonded fiber batt. The
rear, heel seat and waist portion of the illustrative insoles,
comprising both the through layer or layers and the short layer or
layers, has greater density and rigidity and is at least as thick
as and preferably is thicker than the forepart of the insole.
In a preferred method of making the insoles of the present
invention, the non-woven bonded fiber layers which are to form the
insole are assembled in face-to-face relation. The assembly may
comprise at least one through layer consisting of a non-woven
bonded fiber batt having an outline shape corresponding to that of
the insole and one or more short layers at least one of which
consists of a non-woven bonded fiber batt and each of which has an
outline shape corresponding with the outline shape of a rear
portion of the through layer. The assembly may be prepared by
arranging a number of layers of non-woven bonded fiber batt in
face-to-face relation and cutting the insole assembly from the
assembled layers, so that the outline shape of the short layers
correspond with the rear portions of the through layer. It will be
understood that the assembly may be made by cutting the through
layer or layers, cutting the short layers separately and assembling
the pre-cut layers to provide the insole assembly. If desired, a
short layer portion may be made of a non-woven bonded fiber
material having a thickness double or three times the thickness of
the through layer rather than by use of a plurality of short
layers.
The insole assembly is subjected to heat and pressure in either a
high-frequency welding press or a press having electrically heated
platens. The heat and pressure causes the layers to bond together
through the action of the bonding agent in the fiber layers in the
rear portion of the insole assembly, and the rear portion is
consolidated or densified so that it has a greater density and
rigidity than the forepart portion. It is preferred that the
density of the rear portion be at least 50 percent greater than in
the forepart portion.
In a modified form of the invention, in addition to the one or more
short layers of non-wover fiber batt, there is used one or two
short layers (of the same outline shape as the bonded fiber batt
short layer) of a stiff, heat softenable sheet material suitably a
sheet of resin plastic such as polyvinyl chloride, vinyl chloride
copolymers, polypropylene, polystyrene, polyamides or other
thermoplastic or stiff sheet material. The sheet material other
than non-woven bonded fiber batt is preferably selected to be
resistant to nails being pulled therethrough. Also, it is desirable
that the plastic sheet material is of a type of plastic material
which is heated when subjected to a high-frequency electric field.
Where thermoplastic resin sheet, e.g. polyvinyl chloride, short
layers are used, the heat and pressure is preferably supplied by a
high-frequency welding press because the resin such as polyvinyl
chloride is heated rapidly by the high-frequency fields and would
be difficult to heat at a sufficiently fast rate to achieve
adequate bonding in a reasonable length of time if a press of the
heated platen type were to be used.
In carrying out the methods of the invention, it is preferred that
the presser members 24, 26 by which the insoles are heated and
pressed are shaped to impart to the insoles a shape corresponding
approximately to the bottom of a foot.
One of the presser members may conveniently be a suitably shaped
metal member and the other of the presser members may be a
partially shaped resilient member having a flexible electrode
embedded therein, the resilient presser member being such that as
the two presser members are pressed toward each other so that the
resilient member forces the insole assembly against the rigid metal
member and molds it to the shape of the metal member. Where the
insole assembly is to be shaped at the same time as the layers
thereof are bonded together a shank member 28 of metal or other
strong stiff material be bonded to the insole assembly in the
heating and pressing step. Where the press is a high-frequency
welding press, the shank member may be coated with polyvinyl
chloride powder or the like as a bonding agent. Where a metal shank
is to be incorporated in this way it may be unnecessary to provide
a recess for the shank as, provided there is a sufficient thickness
of compressible material, for example non-woven bonded fiber batt
present, the pressure exerted by the press will force the shank
into the layers of the insole assembly and embed it therein.
In the method using a high-frequency welding press, it is necessary
that parts, at least, of the insole assembly comprise material
which is heated by application of a high-frequency electric field.
Preferably where the insole assembly comprises a non-woven fiber
batt the fibers of which are bonded by a binder, the binder will
comprise a material which is heated by application of a
high-frequency electric field.
Conveniently, insoles in accordance with the invention may have a
suitable finish, for example a material comprising 50 parts by
weight of an aqueous dispersion of carboxylated high nitrile
content synthetic rubber having a solids content of about 42
percent by weight and containing zinc oxide as a curing agent, 50
percent by weight of an aqueous dispersion of a vinyl chloride
copolymer having a solids content of from about 55 to about 59
percent by weight, 10 parts by weight of 10 percent sodium
carboxymethyl cellulose as a thickening agent and 5 parts by weight
of a suitable color dispersion, for example a water based
dispersion, instead of a stuck-in sock such as is used in many
shoes at present.
The above and other of the various objects and several features of
the present invention will become more clear from the following
description of illustrative shoe insoles and methods of manufacture
thereof aforementioned, hereinafter set out as Examples 1 to 5. It
will be realized that these illustrative insoles and methods have
been selected for description to illustrate the invention by way of
example and not of limitation of the invention.
EXAMPLE 1
A non-woven fiber batt was formed by garnetting a mixture of fibers
in the ratio of about one third by weight of 4 denier nylon staple
fibers from 1 to 4 inches in average length with no staple
exceeding 71/2inches and about two thirds by weight of viscous
rayon fibers of mixed denier up to 11 (most fibers having a denier
of about 3) and having a mixed staple length between 11/2 inches
and 3 inches. The resulting light-weight, non-woven fiber web was
cross-laid to form a thicker web and this thicker web was passed
through a needle loom to consolidate the web and form an
intermediate non-woven batt. The intermediate batt had a weight of
about 480 grams per square meter, and was between 2.5 and 3.0
millimeters in thickness. This intermediate batt was then passed
through an impregnating bath composed of an aqueous dispersion of
vinyl chloride copolymer having a solids content of from 55 to 59%.
From the bath the impregnated material was passed between stripper
rolls to remove excess impregnant and was dried by passing it
through a drying oven and round heated drying drums (the drums
being heated by steam at 40 p.s.i.). The non-woven bonded fiber
batt so formed consisted of 1 part by weight fiber to 1 part by
weight of binder. The impregnated and dried material was about 2.5
millimeters in thickness.
Next, a piece of non-woven bonded fiber batt, prepared as described
above, measuring 12 inches by 8 inches, was laid on a cutting block
of a cutting press. A second piece of the non-woven bonded fiber
batt measuring 71/4 inches by 8 inches was placed on top of the
first piece with one of its 8 inch long edges in alignment with an
8 inch edge of the first piece and with the 71/4 inch long edges in
alignment with the 12 inch edges of the first piece. Finally, a
third piece of the non-woven bonded fiber batt measuring 71/4
inches by 8 inches was laid on top of the second piece, in
alignment therewith. A cutting die, having the outline shape of an
insole to be made, was placed on the materials, positioned so that
the region of the die which was to cut out a forepart portion of an
insole overlay only the first piece of the non-woven bonded fiber
batt, the line marking the front edges of the second and third
pieces of material lay in a ball region of an insole cut by the die
and a rear region of the die (which was to cut out a heel seat and
waist portion of the insole) overlay the first, second and third
pieces of the material. The press was then operated to cause the
die to cut the material to form an assembly comprising a through
layer (cut from the first piece) having an outline shape
corresponding to that of the insole and two short layers (each
having an outline shape corresponding to that of a rear, heel seat
and waist portion of the insole), the assembly being such that the
outline shape of the short layers corresponded to the outline shape
of the rear portion of the through layer.
The resulting assembly was placed between the platens of a
high-frequency welding press, resting on a silicone rubber sheet
three-sixteenths of an inch thick having a flexible electrode
embedded in it, the sheet being secured to the lower platen and the
assembly was covered by a foam silicone rubber sheet one-half inch
thick. The silicone rubber was provided to prevent loss of heat
from the assembly to the metal platens of the press, silicone
rubber being a thermally insulating material of low dielectric
loss. The air line pressure applied was 80 p.s.i. and the ram
diameter was 41/2 inches. The input power applied was 1.9 amps and
the frequency of the high-frequency field was 39 MHz. The assembly
was allowed to remain in the press under pressure for 15 seconds
and was subject to the high-frequency electric field for the first
9 seconds of this time.
The assembly was next removed from the high-frequency press and the
three layers were found to be firmly bonded together. The forepart
portion of the insole thus formed was about 2 millimeters in
thickness and had a density of about 0.45 grams per cc. (the
initial density of the forepart was about 0.40 grams per cc.). The
heel seat and waist portion of the insole was about 3.10
millimeters in thickness and its density was about 0.78 grams per
cc. The flexural rigidity of the material of the heel seat and
waist portion of the insole was found to be of the same order as
the flexural rigidity of Grade 1 shankboard 3 millimeters thick and
was found to be considerably greater than the flexural rigidity of
the forepart portion of the insole. Heel-attaching pins were driven
through the heel seat and waist portion of the first illustrative
insole and through Grade 1 shankboard 3 millimeters thick: slightly
greater loads were needed to pull the heel pin out of the insole
made according to the Example than were required to pull the pin
from the Grade 1 shankboard.
The insole of the Example was subjected to heating and was then
subjected to an insole molding operation, using a commercial twin
sole molding machine. The molded insole so formed was found to be
suitable for use as an insole in the manufacture of shoes. Insoles
made as described above were suitable for use in the manufacture of
men's shoes without any additional treatement: for use in the
manufacture of women's shoes the heel seat and waist portion was
reinforced in known manner by attaching a metal shank member, using
eyelets.
EXAMPLE 2
The general procedure of Example 1 was repeated, except that three
short layers of the non-woven bonded fiber batt were used in the
heel seat and waist portion. The forepart portion of the insole
(which consisted of only one layer, the through layer, of the
non-woven bonded fiber batt) was slightly over 2 millimeters in
thickness and slightly over 0.4 grams per cc. in density. The rear,
heel seat and waist portion of the insole was 3.6 millimeters thick
and had a density of 0.86 grams per cc. The forepart portion of
this insole had a flexural rigidity similar to that of the forepart
portion of the insole of Example 1. However, the flexural rigidity
of the heel seat and waist portion of the insole made in this
Example was noticeably greater than that of the insole of the first
Example and was of the same order as Grade 1 shankboard 3.5
millimeters thick. The flexural rigidity of the heel seat and waist
portion of the insole was considerably better then that of a Grade
1 shankboard 3.5 millimeters thick after both had been subjected to
soaking in water for 6 hours. The load per millimeter thickness of
the material required to remove heel attaching nails from the heel
seat and waist portion of the insole was significantly greater than
that required to remove nails from Grade 1 shankboard 3.5
millimeters thick, especially after both had been subjected to
soaking in water for 6 hours.
EXAMPLE 3
The methods of Examples 1 and 2 were repeated except that instead
of a high-frequency press, a press with heated platens was used to
supply heat to the assembly. In each case, the thickness, density,
flexural rigidity and the load required to remove the heel pin from
the material were found to be about the same as for the first and
second products. It was found, however, that there was some
tendency for the layers of the product corresponding to Example 2
to delaminate.
EXAMPLE 4
Insoles were made by methods corresponding to Examples 1 to 3 with
the exception that the different impregant composition was used;
namely, a plasticized polystyrene dispersion having a solids
content of about 50 percent. The insoles were similar in properties
to the corresponding one of the Examples 1 through 4, except that
those made using highfrequency heating corresponding to Examples 1
and 2 were slightly less dense than the insoles according to
Examples 1 and 2.
EXAMPLE 5
Further insoles were prepared using a non-woven bonded fiber batt
such as in Example 1 but using an impregant composition comprising
80 parts by weight of an aqueous dispersion of a vinyl chloride
copolymer having a solids content of about 55 to about 59 percent
by weight and 20 parts by weight of an aqueous dispersion of
carboxylated high nitrile-content synthetic rubber having a solids
content of about 42 percent by weight and containing zinc oxide as
a curing agent. The impregnated batt was dried as described in
Example 1 and the impregnating conditions were so chosen that the
ratio of fiber to binder in the dried non-woven bonded fiber batt
was 1:1 by weight.
In making one of these insoles, a piece 12 inches by 8 inches of
the non-woven fiber batt was placed on the cutting block of a
cutting press and a sheet of stiff polyvinyl chloride resin 71/4
inches by 8 inches was laid on top of the non-woven fiber batt with
an 8 inch side in alignment with one of the 8 inch sides of the
non-woven fiber piece and with the 71/4 sides in alignment with the
12 inch sides of the bonded fiber sheet. A further piece of
non-woven bonded fiber batt 71/4 inch by 8 inches was laid on top
of the polyvinyl chloride sheet. An insole assembly was cut from
this and the assembly treated in the high frequency press in the
manner described in Example 1. In this case the polyvinyl chloride
sheet was slightly over one half mm. thick and had a weight of 900
grams of square meter.
The resulting insole had a forepart portion, which was 21/2 mm.
thick and had a density of about 0.4 grams per cc. and had a rear,
heel seat and waist portion which was about 3 mm. thick and had a
density of about 1 gram per cc. The heel seat and waist portion of
this insole had a slightly greater flexural rigidity than the heel
seat and waist portion of the product of the first example. The
load per millimeter thickness required to pull a heel-attaching
nail through the heel seat and waist portion of this insole were
considerably greater than that required for the product of Example
1.
A further insole was made in a manner similar to that just
described except that two layers of the polyvinyl chloride sheet
material were used. The forepart portion of this insole was 21/2
mm. thick and had a density of about 0.4 grams per cc. The rear,
heel seat and waist portion of the insole was 31/2 mm. and had a
density of slightly over 1 gram per cc. This insole had a slightly
greater flexural rigidity than did the product of Example 2 and a
considerably greater load was required to pull the heel-attaching
nails through the heel seat and waist portion.
Both insoles of this example were suitable for use in the
manufacture of shoes.
EXAMPLE 6
Insoles were made by procedures corresponding to Examples 1 and 2
with the exception that a small piece of polyvinyl chloride sheet
material, one-half mm. thick and having a weight of 900 grams per
square meter was placed in the heel seat region prior to assembly
under heat and pressure in the high-frequency press so that the
polyvinyl chloride sheet becomes an integral part of the insole in
the heel seat region into which the heel attaching nails are to be
driven.
* * * * *