Note: Descriptions are shown in the official language in which they were submitted.
This invention relates to a knittecl elastic bandage :Eor surgiGal
or supportive purposes. Mo.re particularly~ it relates to a
knitted bandage of a lightweight open, porous nature in which
overlapping layers cling to each other to form a relatively
non-slipping type of support.
BACKGROUND OF THE TNVENTION.
Historically, elastic bandages have been made in a woVen struc~
ture, using narrow or ribbon looms~ wherein the retractive and
supportive power has been supplied by special warp yarns. Eaxly
bandages employed overtwisted cotton warp yarns, as shown in ~ '
the U.S. paten~,to Teufel, 1~0.8~ No~ 889~827 or to Kle~n~ 1932
No. 1!875~740.
The use'of cotton warp ya,rns has beeD displaced tQ a con'side.rable
extent by.the:use of elastome~ic Wa,rp ya,~ns~ initiall~ of
ext~uded or'cut xubbe~, more xecently o~ ~thér ela,stomex~i.c m~n~
made pol~mers~ Such elastomexlc wa,~p ya~ns are usu~lly ~r.a~pea
with a la~er of'non~ela,sto~eric fil,a.ments,
Such banda~es~ ~lthough.effecti,ye in u~s,e~ suffer f~om the ~-` '
disadv~nta~e'~f being rel'atiyely expen~ye~ They a~e Px~d'uce.'d . ~.
singly Qn ~ na~row lQom~ utiliz~n~ expensi,ye ~xapped eIa'stomer'~c
yarns~ ~t compa,rat~e,ly slo~ p~duction rate$, inherent i~n, t~e
wea~in~ ~rocess,
In an atte~pt to ciXcum~ent the l,i,~ita,tions of the wea~ing
process~ it:ha;s been propo$ed to ~oduce! ela~tlc b~nda~es in.
knitted str.ucture~ as in.U~ S. P~,tent 3265.7Q3, to B~rnh~xdt~.
.~,,9
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377
The knit structu.res thus far proposed, however, skill employ
elastomeric yarns as part of the warp structure, and customarily
employ very heavy filling yarns to prevent necking-in of the
bandage when stretched. They are relativel.y heavy in weight,
averaging 6 to 12 o~. per square yard (204 to 408 grams per square
meter), and due to their compact structure they become hot and
uncomfortable to wear. ~lso, when applied to a limb or other
body member they must be secured in place in the outer wrap by
means of some sort of fastening, such as toothed metal clips. As
the bandage is worn, the layers of the bandage tend to slip and
slide past each other, leading to the undesirable alternatives oE
frequent removal and rewinding or else winding the bandage with ~ ~
an uncomfortable degree of tension. ~: :
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It is with improvements in the production of bandages of this ..
type that the present invention is concerned.
SUMMARY OF THE INVENTION
It has now been found that by the utilization of so-called false ~ .
twisted filament yarns in the warp of long direction, ~ith a
staggered inlay of regular yarns in the cross direction, a new
type of elastic bandage can be produced which has stretch and
power characteristics comparable with the characteristics of
conventional elastic banda~es of woven structure. .:
The bandages of this invention comprise
a set of composite parallel warp yarns in which a false~t~ist
yarn is formed into stitch loop chains with a second false-twis~
-- 2 --
353~7
yarn of opposite twist inlaid into the loops of the f irst
false-twist yarn,
and a plurality of individu~l Eilling yarns describing varied
and cursive patterns inlaid across said compQsite warp yarns,
the filling yarns overlapping one with another across a substan- , ;
tial portion of the width of said bandage,
no individual filling yarn pattern extending across more than
a minor portion of the width of said bandage,
and a portion at least of the length of said filling yarns
lying in slack looped configuration on the surface of said
bandage.
:
~y false-twist yarns is meant ~ type of texturized continuous
filament yarn which has been given increased bulk and loft,
together with stretch, by the introduction into the yarn of
crimps, loops, coils, and crinkles by false-twisting. Such yarns
are commercially produced by well-known processes, and when the ~-
filamentary material is thermoplasticr as is the case with nylon,
a heat-setting stage in the false-twist process renders the
stretch and the crimped configuration of the yarn relatively ~ ~
permanent. ,
Depending on the direction of rot~tion of the spindle, the yarn
may be twisted clockwise or counterclockwiser giving rise to
S-twist or Z-twist in the yarn. It is customary to employ yarns
of both types of twist where it is desired to mini~ize tor~ue
9~3~7
,
and twist in a fabric, either as alternate warp yarns or as a
yarn of one twist plied with a yarn of opposite twist.
The warp yarns in the preferred bandage of this invention consist
of false-twist S or Z yarns, knitted in a chain stitch with a
false-twist Z or S yarn inlay. In order to minimize the tendency ~,
of knitted fabrics to narrow in when stretched, the chain-
stitched warps are held in position by a series of interlocking
filling yarns Qf conventiQn~1 non-elastic type, preferably spun .'
yarns, inla~d in a pa,rticular set of var~ing patterns which '~
will be descrihed more fully herein belo~.
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DESCRIPT.~ON OF THE INVENT:I~ON ::
The invention will be understood more fully with reference to ,:
the following description and drawings, in ,which~
;, .
~ FIGURE I is a magnified isometric view of a segment of a
~.. .i ~
preferred bandage of this inyention in relaxed state.
FIGURE 2 is a magnified view Qf a portion of such a bandage ~,
under 50~ extension.
FIGURE 3 is: a highIy magn-i~ied vie~ of a fal~se-twist yarn used
in the process of this invention.
.. ,.~ , . ~ :.:
r:` r :
F~GURE 4 is a formalized representation of the interrelationship ::
of th.e warp and filling yarns in the'bandages of this invention.
~.,.
~i..'' ~ 30 FIGURES 5, 6, 7 and 8 represent the paths of t~e ~nclividual
"~. _ 4 _ -
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., ,.,
,.,;.",
.. ~ .
~, ,,
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,..
377
filling yarns in one repeat of a preferred embodiment oE khis
invention.
FIGURE 9 is a composite of FIGURES 5, 6, 7 and 8~
FIGURES 10 and 11 represen-t the paths of the individual filling
yarns in one repeat of a second embodiment o~ the invention.
FIGURE 12 is a composite of FIGURES 10 and 11.
For the sake of clarity, the involved nature of the false-twist
warp yarns is shown only in FIGURE 3
Referring now to FIGURE 1, a preferred bandage of this invention
comprises a set of warp yarns 10, interconnected ~y filling yarns
12 which are interlocked with at least a majority of the chain
loops of the warp yarns. The bandage is of an open, porous con-
struction, having an air porosity usually in excess of 500 cubic
feed of air per square foot perminute at 0.5 inches of air -~
pressure, as tested on the Frazier air permeability device (18
cubic centimeters per square centimeter at 5 centimeters). This
porosity is in part due to the lightweight of the bandages of this
invention, which cusomarily lies in the range of 2 to 3 oz per
square yard (68 to 102 grams per square meter), compared with
conventional eIastic bandages which weigh 6 to 12 oæ. per square
y~rd (204 to 40~ grams per square meter).
The lightweight and open weave na~ture of the preferred bandages `
of this in~ention have been found to minimize the tendency of the
false-t~ist inlay yarns of a given type of twist~ S or Z, to
impa~t curl to a bandage, pro~ided that the inlay ya:rns are com-
1~ 339Sa~77
.
bined with a chain stitch yarn of opposite twist. For simplic-
ity in manufacture, therefore, it is desirable to utilize warp
yarns of composite nature, wherein each composite yarn consists
either of a chain stitch S yarn with a Z twis-t inlay, or a Z
twist yarn with an S twist inlay~
The filling yarns 12 in FIGURE I are shown as lying slack, in
cursive or looped configuration on the surface of the bandage.
This relaxed condition of the filling yarns is important in that
10 it allows the elasticity of the false-twist yarns 10 to ~e ~ ;
utilized without any substantial necking-in or widthwise con-
traction when the bandage is stretched. It is due in part to a
heat-shrinkage process to which the bandage is subjected after it
comes from the warp-knitter or crochet machine. Probably in
greater part, however, the relaxed condition of the filling yarns
is due ~o the unusual manner in which the lightweight filling yarns
- . .
are deployed through the warp yarns, as shown schematically in
FIGURES 5, 6, 7 and 8 the arrangement of the individual filling
yarns in a preferred embodiment of the invention, and in F~GURE 9 ~ `
: .
~ 20 a composite of all four filling yarns, each governed by an - ;
,:
individual guide bar. In the bandages of this invention the ;
filling yarns do not progress in uniform fashion acro s the warp
yarns, as in prior art elastic bandages, but are arranged in off- ;;
setting pairs across the banda~e. The pairs may be ar~anged in ~ ~;
diagonal fashion~ as in FIGURES 5 and 6; in reciprocating fashion,
as in FIGURES 7 and 8; in staggered fashion, as in FIGU~ES 1~ and
11; or in ~arious combinations of these. Each individual filling
yarn extends over only a portion of the warp yarns: as illustrat-
ed in F~GURES 5 and 6, the filling yarns 12A and 12B are inlaid
in 9 warp y~rns, in a preferred em~Qdi~ent of the inyen~ion
- 6 -
while the filliny yarns 12C and 12D oE FIGURES 7 and 8 are inlaid
in 5 warp yarns. Since there are 1~ warp yarns per inch in this
bandage, a bandage four inches wide will contain 7 pairs of fill-
ing yarns 12A and 12~ and 11 pairs of yarns 12C and 12D.
Yarns 12C and 12D both terminate their lateral path on a common
yarn: as shown in FIGURE 9, at 14, this is the fifth warp yarn
in a nine-yarn r~peat.
PREFERRED EMBODIMENT OF THE INVENTION . ~;
Using a crocheting machine, a bandage was constructed utilizing
five yarn guide bars per repeat operating in a vertical plane
perpendicular to the horizontal needles, four of the bars moving
across the width oE the fabric to insert the filling yarns of
30/1 cotton and the fifth bar being utilized to insert the
inlaid false-twist yarn lOA or 10B. The filling yarn pattern
was that shown in FIGURES 5, 6, 7, and 8, each of .he yuide bars ~i
operating independently. The composite false-twist yarns 10
were 70~1/17 Z twist inlay and 70/1~17 S twist chain stitch
9uperloft nylon, a trade name for false-twist yarns made on a
Leesona false-twist apparatus. There were nine warp yarns in
each repeat, a total of 57 needles ~eing used in the production
of a ~our-inc~ (10 centimeter) bandage ~it~ 14 composite warp
yarns per inch (5.5 yarns per centimeter). The filling yarn of
30~1 cotton was inserted at the ra~e o~ 17 picks per inch (6.7
yarns per centimeter).
~s seen in FIGURE 4, the cottQn filling yarn is inlaid into each
of the loop-forming S yarns ~n the composite warp yarns,
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FIGURES 5, 6, 7, and 8 illustrate the particular patte.rns with
which each of the four filling yarns i5 deployed, to form the
composite ~illing yarn structure shown in FIGURE 9.
The bandage as formed on the machine has a weight o~ about 60
~rams per square yard or 72 grams per square meter. It is then
conditioned by exposing it, untensioned, to moist stea~ at ahout
140F (60~C) for one to two hours, after which it is dried. Dur-
ing this steaming process the bandage undergoes shrinkage, in-
creasing in weight to about 70 grams per square yard or 84 gramsper square meter. In addition, the filling yarns are relaxed
from their ofE-machine regular configuration to the cursive con-
figuration shown in FIGURE 1. This relaxation builds slack
into the filling yarns, and in part accounts for the ability of
the bandage to be stretched without an accompanying decrease in
width.
The finished bandage had an air porosity of over 90~ cubic feet of
air per square foot per minute at 0.5 inches pressure, as tested
on the Fraziex air permeability apparatus (32 cubic centimeters
per square'centimeter per minute at 5 centimeters pressure).
At I00~ elongation the bandage had 9 picks or filling yarns per
inch (3.5 per centimeter) with.14 composite warp yarns per inch.
Since the filling yarns were 30/1, the filling cover factor was
about 2, ~n extr'emely low fact~x cha,racteristic of open-mesh
netting. Co~er factor is a m,easure of the degree of openness of
a fabric, and is calculated as the number of yarns per inch
divided by the square root of the yarn count in the cotton system.
In the bandages of this invention, the number of filling yarns
. ~ .
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1. , .
5~
per inch of bandage under 100~ extension preferably lies within
the range of 8 to 20 (3 to 7.5 per centimeter~ with the filling
yarns ranging from 20's to 60's in count, so that the cover
factor is less than 5~
This low cover factor in the illing brings the crimpedl curled,
and looped nature of the warp yarns into prominence as a
dominant sur~ace characteristic of the bancLages of this invention.
When the bandage is applied to a body member in the custo.nlary
overlapping layer procedure, each layer of the bandage clings
firmly to each adjacent layer with which it is in contact, due
to the interlocking of the crimps and curls of the warp yarns
in one layer with the warps in adjacent layers and with the open, ~'
widely-spaced filling yarn structure. Thus the bandage resists
slipping and displacement as the body member is flexed during
movement, an advantage not present in conventional elastic ~
bandages. :
~: OTHER EMBODIMENT OF THE INVENTION.
Using warp yarns of 70 denier 23 filament false~twist nylon~ ~ .
arranged in the same S and Z twist p~tterns as in the preferred
example above~ a bandage was constructed utilizin~ three quide
~; bars. T~ bars inserted the 30~1 cotton filling yarns in.the
patterns shown at 12E and 12F in FIGURES 10 and 1.1. The oyerlap
of these yarns is shown at 14 in FIGU~E 12, a compos`ite'o~
FIGURES 10 and 11. ~ain there were nine warp yarns pe~ repeat.
Since only two filling yarns were employed, the third guide bar
waS changed frsm ~hrowing one needle per link ta tWo nee.dles per
link~' so that adjacent warp yarns were held toge-the'r not on'ly by
g _
.
-
the filling yarns but by the inlay false-twist yarn lOA or lOB
of FIGURE 4.
After relaxation by steaming, the bandage we.ig.hed 63 yrams per
square yard ~76 grams per square meter), with 16 warp yarns and 21
filling yarns per inch (6 warp yarns and 8 filling yarns per
centimete.r~. The porosity was in excess of 500 cubic feet of air
per s~uare foot ~er minute at 0.5 inches pressure (18 cubic
centimeters per square centimeter at S centimeters pressure).
Typical ~andages of th.is in~ention are characterized by an ability
to be stretched in substantially the same ranye as conventional ;
elastic bandages, a repr~esentative range being 60% stretch under
a force o~ lO pounds (4.5 kg.) up to 170% stretch under a force :~
of 50 pounds (22.5 kg.). In additiQn to being lightweight and
comfortable to wear( due to their porosity, they are absorbent,
and are easy to wash and sterilize. Since they contain no
rubber or synthetic elastomeric ma~erial, they may be used in
cases where elastomer yarns in contact with the skin give rise
to an allergenic reaction.
It Will be appreciated by those skilled in the art that, unlike
the production of woven bandages on a narrow loom, the knitted
bandages of this invention may be produced on a wide flat-bed
machine, and that a plurality of bandages, of varying widths if
desired, may be produced in a single machine operation using a
tie~in yarn between individual bandages if necessary, said yarn :
being readily removed su.bse~uently by an unraveling operation.
'~
The above description o~ th~ bandage is to be regarded a~
exemplary only, and other size~ ~ y~rn and knit-ting patterns
~,~
- 10 - -
la~s3~7
~ay be ut.ilized without departing rQm the spirit of the
invention.
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