Note: Descriptions are shown in the official language in which they were submitted.
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APPARATUS FOR MAKING HOT MELT
ADHESIVE BONDED PILE FABRICS
~ he ~resent invention relates to pile fabrics. More
particularly the present invention relates to apparatus for manu-
facturing hot melt adhesive bonded pile fabric.q.
Pile fabrics such as carpeting may be manufactured in
several ways such as by weaving, tufting, needling or bonding.
In each methcd the pile must be secured to a base or support
layer in one way or another. The present invention is particular-
ly concerned in one aspect with a method of manufacture wherein
the pile is bonded by means of a hot melt adhesive to a base
layer. Such fabrics will herein be referred to variously as hot
melt adhesive bonded pile fabrics, or hot melt adhesive bonded
carpets.
A number of techniques are kn~wn for the manufacture of
bonded pile fabrics which involve the coating of a preformed base
layer with a layer cf an adhesive and thereafter pressing pile-
forming lengths of a yarn into the adhesive to adhere pile-
forming lengths to the base laver.
The prior commercial techniques for making bonded fabrics
have relied very extensively on the use of PVC plastisol formu-
lations because of the processing disadvantages thought to beassociated with the use of other adhesive formulations such as
hot melt systems. According to such techni~ues a polyvinyl
chloride plastisol was applied to the base layer prior to position-
ing the pile-forming yarn relative to the base la~er. Then the
pile arn may be poritioned into contact with the base .-er and
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-the plastisol may then be fused or cured, typically hy heating.
When attempts were made to substitute other adhesives, such as
hot melt adhesives for the PVC plastisol in this process diffi-
culties were encountered. Thus, for instance, wi-th regard to hot
melt adhesives, it has generally been thought that the apparatus
employed for positioning the yarn may become coated with the ad-
hesive requiring frequent shut downs of the apparatus for cleaning
which is, of course, commercially unattracti~e.
Thus, while PVC plastisol has been the bonding agent of
choice in the ~repara~ion of pile fabrics it is quite expensive,
and it may tend to give off no~ious gases when the product is sub-
jected -to combustion conditions. ~lso, while polyvinyl chloride
(PVC) ~lastisol compositions generally may provide good "tuft
lock" characteristics, that is its use results in a firm bond of
the pile forming yarn to the base layer r PVC plastisols generallv
may not penetrate to the desired extent into the yarn bundles to
effect comple-te adhesion of all pile yarn fibers of the pile yarn
bundle to the pile fabric structure which may result in "fu~zing"
of the end product, especially in carpeting end uses.
Another disadvantage ty~ically associated with the prior
art techni~ues for making non-tufted ~ile fabrics, that is fabrics
where the pile yarn is not tufted through the backing but simply
adhered to the backing, is that the adhesive is normally applied
to the base layer on the side of the base layer facing the pile
yarns, and the base layer is normally of a construction such that
the adhesive will not flow through it but will substantially remai~
on that surface with perhaps some penetration into the base layer.
Then, if it is desired to apply a backing layer, e.g., a hard back,
the bac~ side of the pile fabric as may be desired in the
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¦ making of carpet tiles the backing layer must be either adhered
directly to the backing layer or an additional ~rocess step of
applying adhesive to the back side of the support layer may be
necessary. In ei~her event, there is created numerous distinct
S layers in the finished product, namely pile layer, adhesive layer,
base layer, another adhesive layer and a hard back layer. Such
constructions may inherently have processing disadvanta~es and be
costly to construct. These layers may also be ~ubject to undesirec
separation during use.
The apparatus of the present invention enables
he bonding of the pile-forming yarn to the base
layer to be accomplished by means of a hot melt adhesive which is
a relatively inexpensive and hence commercially attractive ad-
hesive system, which may advantageously flow into the individual
yarn bundles to effect more complete adhesion of all the fibers of
the pile ~onM~ yarn to the pile fabric product. In accordance with
the apparatus herein the hot mYlt adhesive is applied to the base
layer conveniently and in a manner which does not intexefere with
the machinery employed or posi~ioning the pile yarn. This step
in the procedu~e m~ æccmplish an additional function, namely that
of bonding the individual pile-forming yarns to themselves ~ypi-
cally at or near the portion of the yarns nearest the base layer,
thereby providing improved performance characteristics to the pile
fabric product. In addition according ~o the invention, the ad-
esive may be applied to the base layer, which is a liquid-permeabl, ,
layer, from the back of the base layer and it may be forced throuyh
the base layer so th~t a one step ad`hesive layer application may
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both provide a means for bonding the pile yarn to the base layer
l and also provide a means by which a backing layer may be integrall~
¦ affixed to the base layer. The resulting product may be less com-
plicated and costly to manufacture and may have fewer separate and
distinct layers in the final product where undesired separation
may occurO
The pile fabrics made by the present invention are hot melt
adhesive ~onded fabrics which are comprised of a li~uid permeable
base layer, a pile forming yarn adjacent to but not tufted through
the base layer, in pile forming, preferably ~olded, fashion; the
pile forming yarn having been bonded to the base layer by means of
a ho~ melt adhesive applied to the back of said base layer and
forced through said base l~yer into contact with said pile forming
yarn. Pile forming configurations may include the so-called
I-tuft configuration, e.g~, a non-olded configuration, U-tuft
configurations, and loop pile configurations, among others. With
regard to the phrase "folded, pile forming fashion," which refers
to a preferred embodiment, it should be understood that what is
intended is a configuration of the pile yarns where the yarns are
provided with at least one fold at the portion of the varn generall Y
most nearly adjasent to the base layer, e.g~, a cut pile con-
figuration. Another "folded" configuration which is contemplated
is a loop pile configuration where the pile yarns remain uncut in
the form of substantially continuous folded yarns in the final
product. A variety of pile configurations both nonfolded and
folded are illustrated in the attached drawing. According to the
most preferred embodiment the pile yarns are cut to form a folded,
cut pile product.
According to the apparatus of the present in~ ¦
vention a pile forming yarn is positioned in pile forming fashion
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adjacent to one side of a liquid-permeable base layer. There-
after a hot melt adhesive, heated to at least its softening point
is applied to the base layer on the opposite side of the base
layer from the side adjacent to the pile forming yarn. The hot
melt adhesive may be forced, either simultaneously with its appli-
cation or in a separate step, through the base layer into bond
forming contact with the pile forming yarn, and the adhesive
is then allowed to cool, either passively or by active cooling
to a temperature below its softening temperature to thereb~
bond the pile forming yarn to the base layer. The apparatus
includes a m~ans for applying the adhesive and forcing it through
the base layer. It is to be understQod that the apparatus is
not limited to means for applying only a hot melt adhesive but
may include other bonding compositions commonly used in the
making of bonded fabrics such as, for instance, polyvinyl
chloride plastisol formulations, etc.
According to a preferred embodiment of the present in-
vention apparatus is provided wherein two continuous, liquid-
permeable base layers are positioned in a passage where they lie
in substantial ~arallel relationship to one another at a pre-
determined distance from one another; at least one continuouspile ~orming yarn is driven by folder blades alternatively against
the opposing surfaces ~f said base layers when they are at or
near the entrance to the above mentioned passage in such a way as
to position the pile forming yarn relative to the base layers
and to fold it zig-zag. Means are provided for applying to the
back of said base layers a hot melt adhesive and for forcing
said hot melt adhesive through said base layers so that said
hot melt adhesive contacts said pile forming yarn. The hot melt
adhesive is then cooled to a temperature below its softening
point to thereby bond said pile forming
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yarn to said base layers. This la~ter step may accomplish
an additional ~unction, namely that of bonding the individual pile
forming yarns to themselves typically at or near the portion of
the yarns nearest the base layer, thereby providing improved per-
formance characteristics to the pile fabric product. Thereafter,
the base layers may be separated from one another to form two
continuous, hot melt adhesive bonded products. Typically such
separation may be accomplished by means of a stationary or moving
knife blade positioned between the base layers which cuts the pile
yarns along the entire width of the joined base layers to provide
the hot melt adhesive bonded products.
The yarn used in forming the pile may be made of any type
of fiber known to be useful for fusion bonded fabrics such as
carpets, for example nylon, acrylics, polyester, wool, cotton and
rayon.
The hot melt adhesive compositions which may be employed
in the practice of the invention include a wide range of hot
melt adhesives which have been available for many years. Typ-
ically such compositions may have a melt viscosity of less than
about 200,000 cps, preferably less than about 100,000 cps at
30QF. Examples include, for instance, blends of ethylene/vinyl
ester copolymer, petroleum wax and a thermoplastic resin as
disclosed in U.S. Patent Number 3,551,231. Other suitable blends
which may be used include ethylene/vinyl ester copolymer, low
molecular weight, low density polyethylene, micro-crystalline
wax, aliphatic thermoplastic hydrocarbon resin, dicyclopentadiene
alkylation polymer, antioxidant and filler as disclosed in U.S.
Patent Number 3,684,600. Other suitable hot melt adhesives of
the ethylene/vinyl ester type which may be used are d~sclosed in
U. S. Patent
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Numb~rs 3,583,936, 3,676,280, 3,684,600, 3,745,054, 3,723,371,
3,911,185, 3,914,48~ and 4,~12,547.
Other hot melt adhesive formulations which may be employed include
those of the atactic polypropylene type. In general such com-
positions may contain a predominant amount, e~g., from about 10
parts to about 100 parts or more, preferably from about 60 parts
to 100 parts, by weight atactic polypropylene; from 0 to about 70
parts of another compatible thermoplastic matexial such as hvdro-
carbon resins~ waxes, polyethylene, especially ~inear, low density
polyethylene; isotactic polypropylene, polyisobutylene and poly-
butene-l. Fillers in widely varying amoun~s may be added to such
compositions as will be readilv apparent to those skilled in the
art.
Other compatible thermoplastic materials which may be em-
ployed in the adhesive formulation include ethylene/ethyl acrylate
polyacetals, polyes~ers, pol~styrene, polyacrylonitrile, polyacry-
lic ester, polymethacrylic ester, polyvinyl chloride, polyvinyli-
dene chloride, polyvinyl acetate, polyvinyl acetal, polyvinyl
ether, polytetrafluoroethylene, polyamide, coumarone/indene resins~
natural resins, hydrocarbon resin, bitumen and others.
The amount of hot melt adhesive applied may vary widely,
based upon the particular pile yarn employed, base layer and pro-
perties desired in the pile fabric product. In general the amount
employed may be from about 2 to about 200 ounces, ~referably about
4 to about 80 ounces per square yard. Tuft binds for carpet yarns
that may be achieved according to ~he invention may be from about
2 to about 20 pounds.
Suitable liquid-permeable base layers which may be employed
n the product and process of the nvention include woven fabrics,
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knitted fabrics, non-woven scrims, felted materials, or even
flexible~ foraminous materials.
Where it is desired to provide the hot melt adhesive
bonded pile fabrics of the present invention as floor covering
1 products, especially carpet tiles, it may be desirable to apply
any of a wide variety of suitable, resilient backing layers to
the fabric. Such carpet tiles are also considered to be within
the scope of the present invention. The backing laver may be
formed, for example, from a suitable thermo~lastic material such
as blends containing ethylene/vinyl acetate copolymers, atactic
polyPro~ylene, bitumen, hydrocarbon resins, wa~es, synthetic and
natural rubbers.
The backing may be bonded to the base layer by means of the
same adhesive applied to the base layer to bond the pile fibers.
Thus, the resulting product may have fewer separate layers subject
to separation than known carpet tiles. This is, rather than
having pile layer, adhesive layer, base layer, another adhesive
layer and backing layer, the present car~et tile may typically
have a pile layer; a single, integral, hot melt adhesive layer int
which the base layer may be disPosed or suspended, and a backing
layer bonded ~o the com~osite by means of the hot melt adhesive.
The backing layer may be provided with at least one stiffening and
stabilizing membrane, such as woven or nonwoven glass fibers.
After the backing has been applied the consolidated material may
then be severed by suitable cutting means into a carpet tlle b~
any of a variety of techniqu-es which are well-known to those
skilled in the art.
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The resulting carpet tile product is suitable for use as
a floor covering in home and/or commercial use in an office en-
vironment where substantial high stress conditions (e.g., wheeled
l traffic) are applied across the tiles. The tiles typically have
a dense pile and may not require adhesives for installation. The
individual rnodules may be replaced or rotated as necessary or de-
sired. The carpet tiles may also have excellent dimensional sta-
bility with substantially no curling, slipping, buckling, stretchil ~g
or shrinking. In addition the carpet tiles may have low smo~e
emission and low ~Ifuzzing~ characteristics.
The invention may be further understood by reference to the
drawings and accompanying description thereof. It is to be under-
stood, however, that various changes may be made without departing
from the scope or spirit of the invention which is to be limited
only by the scope of the appended claims~ Referriny now to the
drawings:
Figu~e 1 is an elevation view oE the apparatus; and
Fi~ures 2 through 4 illustrate various embodiments for
forcing the adhesive through the base layer.
Figures 5 through ~ illustrate various pile forming con-
figurations which may be employed in the hot melt adhesive bonded
pile fabrics of the present invention. Figures 9 and 10 illustrat~ ,
conventional tufted pile fabric configurations showing the pile
yarns tufted through a base layer. Figure 11 illustrates a con-
ventional I-tuft bonded fabric configuration showing a relatively
impermeable base layer.
Referring now to Figure 1, carpet yarn 10 is supplied from
a yarn source (not shown) over and around guide rolls 12 and 14
nd down to the vertical guides 16 ~ase layer 17 is supplied
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from rolls 18 into position between the guides 16. As the yarn
¦10 enters between the vertical`guides 16 the folding blades 20 and
¦22 alternately displace the yarn in a zig-zag Eashion into one or
the other of the base layer sheets 17 as the carpet backing is
being drawn downwardly. Pivotally mounted bladelets 24 and 26 may
assist in the folding of the yarn. Folding blades 20 and 22 are
mounted, respectively, to connecting rods 28 and 30. Connecting
rod 28 is pivotally connected to pivot shafts 32 and 34 and con-
necting rod 30 is pivotally connected to pivot shafts 36 and 38
through suitable links (not shown). The shafts 32 and 38 are
oscillated by an oscillating cran~ arm mechanism (not shown).
It should be noted that the blade 20 is out of phase with
the blade 22 so that when the blade 22 is being pivoted inwardly
as shown in Figure 1 the blade 20 is being pivoted outwardly and
vice versa to provide a zig-zag configuration of the yarn between
the carpet base layers 17 which are liquid-permeable, that is
permeable to the adhesive to be applied.
After -the ~arn has been positioned in zig-~ag configuration
between the carpet base layers 17, hot melt adhesive 80 maintained
in troughs 82is applied to applica-tor rolls 84 by passing through
gaps 86 between the side walls 88 of the troughs 32 and the aDpli-
cator rolls 84. The hot melt adhesive may be maintained in the
liquid phase by heating means not shown. The amount of adhesive
applied to the applicator rolls may be adjusted as desired by
moving troughs 82 upwardly or downwardly as indicated. Applicator
rolls 84 are caused to move preferably in the directions indicated
by drive means not shown whereby adhesive is applied to the carpet
base layers 17 and simultaneously forced through the base lavers
into contact with yarn 10. The rol~ls may also be forced to move
in the opposite direction to the directions indicated if so
desired.
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After the hot melt adhesive has been applied to the carpet
/- base layer and forced through it into contact with the carpe-t yarn,
it may be converted into the solid phase by cooling means 90 to
form a bond between the carpet yarn 10 and the carpet base layers
17. Cooling means 90 may be supplied wi-th air blowers 92, cooling
coils 94 over which air is forced and thereby cooled prior to
exiting the cooling means through exit ducts 96 into contact with
the carpet base layers to thereby cool the hot melt adhesive causir g
it to revert to the solid phase. The yarn 10 may then be severed,
generally in the middle of ~he base layers 17 by cutting blade 98
to provide, simultaneously, two sheets of car~et.
Figure 2 is an enlarged view of the hot melt adhesive appli-
cator means embodiment 78 shown in Figure 1. Numbers in Figure 2
corresponding to numbers used in preceding drawings refer to cor-
responding parts of the apparatus. The gaps 86 by means of which
the amount of hot melt adhesiv~ t~ be applie~ may be adjus-ted as
desired are more clearly illustrated. Also shown in Figure 2 are
pre-heating plates 101 which may be provided to pre-heat the base
layers prior to application of hot melt adhesive and to facilitate
such application.
Figure 3 illustrates an alternative embodiment wherein the
hot melt adhesive is maintained in a reservoir sided on one side
by base layers 17 and on the other side by doctor blades 104. The
adhesive 80 is allowed to contact the carpet backings and is
forced therethrough by the tips 106 of doctor blades 104.
Figure 4 illustrates yet another embodiment of the inventior
where the hot melt adhesive is maintained in tanks 108. Appli-
cation of the adhesive to the base layers 17 is accomplished by
drawing e adhesive out of the tanks 80 through p~lmps 110 into
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manifolds 112. The adhesive is then forced from the openings 114
in manifolds 112 under sufficient pressure to force the adhesive
through the carpet base layers 17 into contact with carpet yarn
I 10,
¦ Figure 5 illustrates an embodiment of the present invention
showing an I-tuft configuration of the pile yarns, base layer 17
in the form of a relativel~ open-weave, adhesive permeable fabric.
Hot melt adhesive 80 is shown as a continuous layer into which the
base layer 17 has become embedded at the base thereof. A backing
layer 150 made of a thermoplastic material is shown as having been
bonded to the pile fabric by means of the same hot melt adhesive
80 used to bond the pile forming yarns. Figures 6, 7 and 3
illustrate some folded configurations of the pile forming yarns
which may be preferred. Identifying nur~ers refer to the same
structural components as in Figure 5. Figure 6 shows a folded,
cut pile configuration. Figure 7 shows a loop pile configuration.
Figure 8 shows another folded pile configuration where the folded
portion of the yarn is on the surface giving the appearance of a
loop pile, although the locps are not joined to one another at
their base. This configuration provides in essence a loop pile
product while simultaneously offering the advantages of, for
instance, yarn savings of the so-called I-tuft configuration.
Figure 9 illustrates a conventional cut pile tufted carpet
tile having pile yarn 10 tufted through a conventional, polvpropv-
lene backing 152, adhesive layer 153, and backing layer 15~.
Figure 11 differs from Figure 10 only in the illustration of a
loop pile tufted configuration rather than a cut pile configuratior L.
Figure 11 illustrates conventional, multilayered I-tuft bonded
roduct showing the configuration ot ~ile yarns 10, adhesive layer
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155, adhesive impermeable base layer 156 in the form of tightly
woven jute, another adhesive layer 157 by means of which backing
layer 158 may be adhered to the base layer.
The invention may be further understood by reference to
the following examples which are not to be construed as unduly
limiting the invention.
EXA~PLE 1
Using a machine similar to that shown in Figure 1, a nylon
carpet yarn was folded between layers of a woven rayon fabric.
By means of an electrically heated plate mounted on one side only,
directly below the vertical guide 16, the varn loops in contact
with the fabric at this side only were lightly fused to the fabric.
By omitting the hot-melt adhesive application and the cutting by
~he blade, a loop-pile fabric was produced on removal of the other
non-adhering rayon fabric.
A hot-melt adhesive composition was formulated using atactic
polypropylene, hydrocarbon resin and wax, and a molten film of
this adhesive cast on a hot-plate at about 350F. A portion of
the loop-pile fabric made as described above was contacted on the
loop-pile face with a piece of non-woven glass scrim. This
assembly was then placed with the glass in contact with the hot-
melt adhesive, rolled to force the adhesive through the glass and
into the loop-pile yarns, and cooled. Then the glass side of the
sandwich was lamina-ted under heat and pressure to a 60 mils thick
sheet of Keldax~, (a trademark of DuPont for a filled hot-melt
composition based on a copolymer o~ ethylene and vinyl acetate).
A blade was then used to cut the yarn sandwich between the rayon
bric and the glass, thue produclng two cut-pile carpets.
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Single yarns were then pulled from the carpet bonded by
the hot-melt adhesive to the glass. The average force required
was found to be 4.6 pounds.
EX~MPLE 2
Used a machine similar to that of Figure 1 with a heater
plate as described in Example 1. There was a rayon fabric on the
same side as the heater plate, an o~en leno-woven ~lass scrim
fabric on the non-heated side, and a nylon carpet yarn folded into
the gap. The glass side of the sandwich was contacted with a
heated applicator ~iden~i~ied as Number 84 in Figure 1), above
which was mounted a trough 88 containinq the following formulated
hot-melt adhesive at about 300F:
Elvax~ 350 (DuPont ethylene/vinyl 30 parts
acetate copolymer
melt index - 19)
Shellmax*400 (Shell micro crvstalline 45 parts
wax, melting point 177~F)
Piccopale*100 (Hercules hydrocarbon 25 parts
resin, softening
point: 212F)
By varying the speed of the application roll relative to the yarn
sandwich~ and the gap between the trough and the applicator roll,
various levels of adhesive were applied to ~he yarn loops through
the woven glass scrim. After cooling and cutting of the yarns to
make two cut-pile carpets, the tuft bind was measured on the glass
backed carpet portion. Values varied from 4 pounds tuft bind with
15 ounces/square yard of adhesive to 6 pounds with 50 ounces/squar
yard of adhesive.
EXAMPLE 3
A hot-melt adhesive was formulated as follows:
I *Trader~rk
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Elvax*350 30 parts
U~ 653-04 (U.S. Industries ethylene/ 10 parts
vinyl acetate copol~mer,
melt index: 375)
Shellmax*500 (Shell micro crystalline 35 parts
wax, melting point 171F)
Piccopal~ 100 25 parts
Using the procedure of Example 2, this adhesive was applied to the
glass side of the yarn sandwich giving tuft bind ranging from 7 to
10 pounds with an adhesive pick up of 32 to 48 ounces/square yard.
EXAMPLE 4
With the following hot-melt adhesive formulation:
Elvax*260 (DuPont ethylenefvinyl 35 parts
acetate copolymer
melt index: 6)
Shellmax*400 40 parts
Piccopale*100 ~5 parts
and using the procedure of Example 2, obtained a tuft-bind of 5
pounds with as low as 8 ounces/s~uare yard of adhesive. With 36
ounces of adhesive, the tuft bind was 9 pounds.
EXAMPLE 5
Used the same procedure as for Example 2, except that the
heated applicator roll/trough to apply the hot-melt adhesive was
replaced by a doctor blade applicator on the glass side as depicted
in Figure 3. The adhesive was:
Elvax~ 660 (DuPont ethylene~vinyl acetate 20 ~arts
copolymer
melt index: 2.5)
D-8~ (Hercllles experimental hot-melt 80 parts
adhesive)
With an adhesive pick u~ in the range of 5-20 ounces/square yard
following from the relatively high viscosity of this adhesive, the
tuft-bind averaged 4 pounds.
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*Trademark
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¦ EXAMPLE 6
¦ Used the method of Example 5, but with a lower viscosity
adhesive prepared thus:
Atactic polypropylene 83 parts
Dowlex* (Dow linear low densit~ 17 parts
polyethylene, melt index: 20)
A 3 pound tuft-bind was obtained with adhesive pick ups in the
range 14-30 ounces/square yard.
*Tr~demark
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