Note: Descriptions are shown in the official language in which they were submitted.
2091884
WO 92/06232 - 1 - PCT/US91/07320
S POI,YE8TE:R/VI8CO8B COMPO~I!I!E: YARN8 AND
FA}IRIC MATE R~A~ CO~I!AINING ~AID YARN8 AEI
F$B~IB E~ COATED ABR~8IVE ~lJPPORT
,D OF T~lS IN~E2~q!ION .
lo The present invention relates to composite
polyester/viscose spun yarns and fabrics containing the
same. The present invention also relates to a method of
making composite polyester/viscose spun yarns and fabrics
containing the 6ame. `
D-~or~ption Or th- R~ t-~ Art
Conventional, flexible backing for coated abrasive
articles include cloth fabrics containing combed cotton
yarn (e.g., combed Egyptian cotton yarn). Such flexible
backings are woven textiles typically prepared by weaving
a sized combed cotton warp yarn and an unsized combed
cotton weft yarn.
The warp yarns are typically sized to aid in the
consolidation of the warp yarns during weaving. The
sizing agent, however, decreases the adhesiveness of
materials attached to the sized fibers. To improve the
adhe~ive coupling, as well as the flexibility and surface
gualities o~ the wovon ~abric, the warp yarns are usually
desized by conventional desizing techniqu~s. The desized
warp y~rn6 are usually then stretched in an aqueous-based
solution or disper~ion. The woven fabric optionally is
presizQd, backsized, or both.
The re6ulting woven fabric is then coated on one face
(preferably, the front face) with an abrasive layer
comprising a bonding material and abrasive grains or
particle~. -
The commercial success of woven textile backingsco~prising combed cotton yarn resides in the qualities of
flexibility, surface condition and cohesion, and, most -
particularly, tensile strength. Woven fabric comprising
;~ combed Eqyptian cotton yarn, when conditioned at zero
percent relative humidity and at a temperature of about
~: -
,
Wog2/o6232 2 ~ 918 8 ~ - 2 - PCT/US91/07320
20-25C, generally have a weight of up to 220 g/m~, a
tensile strength in the warp direction of about 140
daN/5cm and a tensile strength in the weft direction of ~;
about 60 daN/5cm.
There have been several attempts, with varying
degrees of success, to make suitable woven f abrics for use
as coated abrasive backings from fibers other than the
relatively expensive cotton fibers.
For example, U.S. Pat. No. 3,316,072 (Voss) states
the use of synthetic fibers such as polyester fibers in
fabrics used as backings for coated abrasive have not been
successful because the adherence of adhesives to the
synthetic fibers is practically nil. To overcome this
adhesion problem, patentee made yarns having synthetic
fiber cores with a sheath of cellulose fibers. Although ~-
patentee states wov~n fabric made from the composite
cotton/synthetic yarn has higher tensile strength and
greater resistance to tear than woven fabric made with
conventional cotton yarn, woven fabric made from the
composite cotton synthetic yarn is slightly less flexible
than woven fabric made from conventional cotton yarn.
U.S. Pat. No. 4,035,961 (Pemrick et al.), which
teaches a woven heat stretched fabric of~polyester yarns,
states that the u~e of fabrics made from man-made fibers,
with the exception of polynosic rayon, have had limited
succe~5 as coated abra5ive backing~ because o~ poor
adhesion Or the coated abrasive bond sy6tem to the fabric.
U.S. Pat. No. 4,282,011 (Terpay) discloses a woven
fabric comprising glass fibers cushioned from each other
by organic fibers (e.g., fibers of cotton, polyester,
polyester-cotton blend, nylon, wool, acrylic, acetate, and
mixtures thereof) in the warp direction and organic fibers
in the weft direction.
Great Britain Pat. No. 1,251,676, published October
27, 1971, teaches a method of making a fabric comprising
interwe~ving weft yarns and sized warp yarns; finishing
the resulting woven fabric with a finishing agent which
contains an organio solvent emulsified in an aqueous
. . .
2Q~18~4
W092/06232 - 3 - PCT/US91/07320
medium, the organic solvent being a swelling agent at
temperatures of 15 to 45OC and a solvent at temperatures
a~ove 65 to 200C; and heating the finished fabric to a
temperature at which the organic solvent is a solvent for
the size on the warp yarns so that the finish is bonded to
the size. By virtue of the inclusion of the emulsified
organic solvent in the finishing agent, the finish is
finely adhered to the size on the warp yarns, providing a
surface to which adhesives can satisfactorily be adhered.
Suitable yarn materials are said to include fibers of
cotton, polynosic, rayon, polyester, polyamide, and
polyacrylonitrile, depending on the particular proportion
and type of fiber, as well as the particular properties
(e.g., wet strength) desired.
French Pat. Appl. No. 2,578,860, published September
19, 1986, discloses a co-textured yarn comprising at least
two continuous multifilamentary filaments (a synthetic
filament such as those made of polyamide, polyester,
polyolefin, and polyvinyl chloride and an artificial
cellulosic ~ilament such as those made of rayon) which are
twisted together. Although Applicant suggests spinning a
yarn from staple fiber and polyester fiber, there does not
appear to bo a spocific mention of spinning viscose (
e.g., rayon) fibers and polyester fibers, nor does there
appear to bo a ~uggestion of useful ratios o~ fibers to
spin.
Bu~arv of tho Tnvention
The present invention provides a composite
polyester/viscose spun yarn comprising viscose fibers and
polye~ter fibers. Preferably! the composite
polyester/viscose spun yarn comprises viscose fibers in
the range from about 35 to about 70 percent by weight and
polyester fibers in the range from about 65 to about 30
percant by weight, based on the total weight of the
composito polyestor/viscose spun yarn. The
polye~ter/~iscose spun yarn can further comprise
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, ' . : ' ! .' . ' ', , , ' , , ',' ', ' .' : ' ' , : ', : ' , . ~, : .',; ' ' , " ,~ . '
W092/06232 _ 4 _ PCT/US9l/07320
209~8~ .
conventional fibers such as fibers of cotton, polyamide,
acrylic, and combinations thereof.
In another aspect, the present invention provides a
fabric material comprising at least 25 percent by weight
of composite polyester/viscose spun yarns according to the
present invention, wherein the fabric has a dry weight up
to about 350 g/m2. The term "dry weight" as used herein
refers to the weight per unit area of a fabric conditioned
at zero percent relative humidity and at a temperature of
about 20 to 25C.
In another aspect, the present invention provides a
method for wet stretching the woven Sabric, the method
comprising the steps of:
(a) providing a woven fabric having sized warp
yarns, the woven fabric comprising at least 25 percent by
weight of composite polyester/viscose spun yarn according
to the present invention, wherein the woven fabric has a
dry weight up to about 350 g/m2;
(b) stretching the sized woven fabric parallel to the
warp yarns in an aqueous enviFon~ent (i.e., while it i
wetted by an aqueou~-basQd solution or dispersion); and
(c) drying the stretched woven fabric at a
temperature of at lea~t about 9O-C.
Fabric according to the present invention has
strength, stretch, ~lexibility, and adhesive adherence
properties equal to or better than comparable fabric
materials made from combed cotton ~ibers. Surprisingly,
fabric according to the present invention has such
flexibility and adhesive adherence properties without the
need to desize the fabric.
The method according to the present invention for wet
stretching woven fabric comprising the polyester/viscose ~ -
spun yarn is advantageous over wet stretching methods
which use organic solvent-based solutions or dispersions
because u~e of an aqueous-based solution or dispersion
eliminates the safety hazards of organic solvents from
personnel and fro~ the environment.
.. , ~, ~, . . . . , . . . . , , .. -. . . - .: .
. . .. ; .
20~88~
W092/06232 _ 5 _ PCT/US91/07320
The fabric material according to the present
invention is useful as a backing or support mem~er for a
coated abrasive article.
D~tailed Description o~ t~e Preferred Embodiment~
Suitable viscose fibers include rayon fibers, spun
staple rayon fibers, and combinations thereof. The
preferred viscose fibers are spun staple rayon fibers.
Viscose fibers are commercially available, for example,
under the trade designation "LENZING MODAL HIGH TENACITY
FIBERS" from Lenzing Ltd. of Lenzing, Austria.
The viscose fibers preferably have a high tenacity
such that a compos$te polyester/viscose spun yarn
according to the present invention, when conditioned at
about 65 percent relative humidity and at a temperature at
about 20C, has a tenacity of at least about 25 cN/tex.
Preferably, the viscose fibers have a staple length
in the range from about 32 to about 40 mm and a linear
dens$ty in the range from about l.3 to about l.7 dtex.
Suitable polyQster fibers are commercially available,
for example, under the trade designation UTERGAL Tlll
FIBER" ~rom Rhone-Poulenc Ltd. of France. -
The polyester ribers preferably have a staple length
in the range from about 25 to about 50 mm and a linear
Z5 d~nsity in the range from about l.3 to about l.7 dtex.
More pre~-rably, the polyestQr ~ibers have a linear
donsity in the range from l.3 to about l.5 dtex.
Tha yarn is spun from the fibers using conventional
spinning tschniques such as ring spinning.
Preferably, the composite polyester/viscose spun yarn
according to the prQsent invention has, when conditioned
at about 65 percent relative humidity and at a temperature
of about 20C, metric number of at least about 28 m for
about 1 gram, and a tenacity of greater than about 20
cN/tex, and more preferably, a tenacity of at least about
25 cN/tex.
A f~bric according to the present invention
comprising composite polyester/viscose spun yarns
'~' .
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w092/0623~ 88~ - 6 - PCT/US91/07320
comprising substantially greater than about 65 percent
viscose fibers typically has inferior stretch (i.e.,
excess stretch) and break strength properties as compared
to fabric comprising about 65 percent by weight viscose
fibers. on the other hand, a fabric material according to
the present invention comprising composite
polyester/viscose spun yarns comprising substantially less
than about 30 percent by weight viscose fibers typically
has inferior flexibility as compared to fabric comprising
greater than about 35 percent by weight viscose fibers.
The most preferred weight ratio of polyester fibers to
viscose fibers is about 1:1. A fabric comprising a
polyester/viscose spun yarn comprising such a polyester
fiber to viscose fiber weight ratio typically exhibits the
optimum compromise of strength, stretch, and flexibility.
The fabric according to the present invention
preferably comprises at least 25 percent by weiqht of the
composite polyester/viscose spun yarns.
The fabric according to the present invention can be
one of a nonwoven fabric, a woven fabric, or a knitted
fabric. The most preferred fabric is woven and comprises
spun staple rayon fibers and polysster fibers, wherein the
weight ratio of polyester fibers to viscose fibers is
about 1:1.
Woven fabric can be made using conventional
techniquo~ such as rapier weaving, air jet weaving, water
~et weaving, or fly-shuttle looming. Nonwoven fabric can
be ~de, for example, using conventional air lay
mechanical, wet lay, spun bond, or stitchbond techniques.
Xnitted fabric can be made using conventional techniques
~uch as stitchbonding.
A woven fabric according to the present invention has
at l~ast one of warp yarns and weft yarns comprising the
composite polyester/viscose spun yarns. The woven fabric
can further comprise one of yarns comprising polyester
fibers, viscose fibers, cotton fibers, polyamide fibers,
acrylic fibers, and co~binations thereof. Preferably, the
fabric according to the present invention has a dry weight ~ -~
, ~ ` ` ' ~ ' .
~0918~
W092/06232 _ 7 PCT/US91/07320
in the range from about 80 to about 300 g/m2. More
preferably, the fabric material has a dry weight
corresponding to one of the known varieties of textile
fabrics such as J weight (i.e., having a dry weight in the
range from about 160 to about 200 g/m2), X weight (i.e.,
having a dry weight in the range from about 220 to 260
g/m2), and Y weight (i.e., having a dry weight in the range
from about 260 to about 300 g/m2).
A preferred method for wet stretching a woven fabric
according to the present invention comprises passing the
woven fabric through a conventional aqueous-based solution
or dispersion used for wet stretching fabric, while under
a load in the range from about 0.25 to about 25 kg/cm,
wherein the aqueous-based solution or dispersion is at a
temperature in the range from about 15 to about 150C. ~o
change the color of the woven fabric, the aqueous-based
solution or dispersion can contain a conventional dye or
colorant.
Preferably, the (wet) stretched woven fabric is dried -
at a temperature in the range from about 110 to about
200C.
~he fabric according to the present invention can
optionally be presized or backsized with conventional
materials for thi~ purpose. The presize or backsize
material can be applied to the ~abric using conventional
coating techniques.
Preferably, the woven fabric according to the present
invention, when conditioned at about 65 percent relative ~ ~ -
h~ dity and at a temperature at about 20C, has a tensile
~trength of at least about 70 daN/5 cm.
Tbe fabric according to the present invention can be
used as a backing for a coated abrasive article.
Preferably, the fabric material is a woven fabric. Such a ~ ~
woven fabric material, when conditioned at about 65 ~ -
~5 percent relative humidity and at a temperature o~ about
20C h~ a lengthwise elongation value up to about 8
percent under a load of about 90 daN/5cm. ~ore
preferabl~, the woven $abric, when conditioned at about 65
2 0 9 ~ 8 8 ~ - 8 - PCT/US91/07320
percent relative humidity and at a temperature of about
20-C has a lengthwise elongation value in the range of
about 4.5 percent under a load of about 90 daN/Scm.
A coated abrasive article according to the present
invention may be in any conventional form, including those
having a abrasive layer comprising a make layer, abrasive
grains, a size layer, etc., and other functional layers
(e.g, a supersize layer), and those having an abrasive
monolayer derived from a slurry layer comprising a bond
system and abrasive grain, and other functional layers.
With the exception of the woven fabric backing
according to the present invention, the coated abrasive
article can be prepared using materials and techniques
known in the art for constructing coated abrasive
articles. The preferred bond system is a resinous or
glutinous (e.g, hide qlue) adhesive. Examples of typical
resinous adhesive include phenolic resins, urea
formaldehyde resins, melamine- formaldehyde, epoxy resins,
acrylate resins, urethane resins, and combinations
thereof. The bond system may contain other additives
which are well known in the art, such as, grinding aids,
plasticizers, fillers, coupling agents, wetting agents,
dyes, and pigments. Preferably, the abrasive grains are
selectQd from such known grains as fused aluminum oxide,
heat-troated aluminum oxide, ceramic aluminum oxide, co-
fuDed alumina zirconia, emery, flint, garnet, silicon
carbide, diamond, cubic boron nitride, ~nd combinations
th-r-of.
Examples of useful materials which may be used in the
supersize coat may include the metal salts of fatty acids,
urea-formaldehyde, novolak phenolic resins, waxes, mineral
oils, and fluorochemicals. The preferred supersize
pro~uces a metal salt of fatty acid such as zinc stearaté.
In a preferred conventional method for preparing a
coat~d abrasive article, a make coat is applied to a maior
~ur~ace of the fabric according to the present invention
followed by proje~ting a plurality of abrasive grains into
the make coat. It is pref-rable in preparing the coated
,
.
. .
I . ~. , ., ~ ' i ., ~ , ' .
2 0 ~ 4
W O 92/06232 _ 9 _ P ~ /US91/07320
abrasive that the abrasive grains be electrostatically
coated. The make coating is cured in a manner sufficient
to at least partially solidify it such that a size coat
can be applied over the abrasive grains. Next, the size
coat is applied over the abrasive grains in the ~ake coat.
Finally, the make coat size coats are fully cured.
Optionally, a supersize coat is applied over the size coat
and cured.
In another preferred conventional method for
preparing a coated abrasive article, a slurry containing
abrasive grains dispersed in a bond material, is applied
to a major surface of the backing. The bond material is
then cured. Optionally, a supersize coat is applied over
the slurry coat and cured.
In the above methods, the make coat and size coat or
slurry coat can be solidified or cured by means known in
the art, for example, heat or radiation energy.
The coated abrasive article can be in the shape of
conventional coated abrasive articles, for example, disc,
sheets, belts, and strips.
Object~ and advantages of this invention are further
illustratQd by the following examples, but the particular
materials and amounts thereof recited in these examples,
as well as other conditions and details, should not be
construed to unduly limit this invention. All parts and
p~rcentages ~re by weight unless otherwise indicated.
Exam~les
E~ L-~3
Examples 1-3 illustrate the preparation of composite
polyester/viscose spun yarns. The polyester fibers
(ccmmercially available under the trade designation
"TERGAL Tlll FIB~R" from Rhone-Poulenc ~td.) had a denier
of about 1.5 dtex, a staple length of about 38 ~m (over a
range of about 30 to about 40 mm), a tenacity of about 62
to about 64 cN/tex (~iber conditioned at 65 percent
relative humidity and at a temperature of about 20C) and
a elongation at break of about 16 percent at break (fiber
:,
. :~
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... . . ... , - . ~ . ~ . . .
w092/0623~ ~ t 8 8 ~ - lo - PCT/US91/07320
conditioned at about 65 percent relative humidity and at a
te~perature of about 20C). The viscose fibers were spun
staple rayon fibers (commercially available under the
trade designation "LENZING MODAL ~IGH TENACITY FIBERS"
from Lenzing Ltd.) which had a denier of about l.7 dtex, a
staple length of about 40 mm, a tensile strength of about
34 to 36 cN/tex (fiber conditioned at about 65 percent
relative humidity and at a temperature of about 20C), and
an elongation at break of about 13 to 15 percent at break
(fiber conditioned at about 65 percent relative humidity
and at a temperature of about 20C).
The polyester fibers and spun staple rayon fibers
were made into composite polyester/spun staple rayon yarns
having a polyester fiber to spun staple rayon fiber weight
ratio of about l to l using the conventional ring spinning
technique, wherein the fibers were twisted in the range
from about 600 to about 850 twists per meter of length.
The polyester and spun staple rayon fibers were then
carded, doubled, and stretched. The resulting yarns,
Examples 1 to 3, had metric values of 34, 40, and 50
meters for l gram (i.e., metric number) (mn of 34, 40, and
50).
The following comparative examples were al90
prepared. Comparative A, a polyester yarn, consisted
2S e~entially o~ polyester ~ibers ("TERGAL Tlll FIBERS").
Comparative B, spun staple rayon yarn, cons~sting
ee~entially of spun staple rayon fibers ("LENZING ~ODAL
HIGH T~NACITY FIBERS"). Comparative C, combed Egyptian
cotton yarn, consisted essentially of combed Egyptian
cotton fibers (com~ercially available from Hoffe of Salle,
GermanyJ. Comparative D, a composite polyester/Egyptian
cotton yarn, consi~ted assentially of about 50 weight
p~rcent polyester fibers ("TERGAL Tlll PIBERS"), and about
50 weight percent combed Egyptian cotton fibers (from
Hoffa).
The tenacity and elongation at breaX for each yarn,
when conditioned at about 65 percent relative humidity and
209~ ~4
W092/06232 ~ PCT/US91/07320
at a temperature of about 20C, are provided in Table 1 .
below.
The results in Table 1 below show the similarity in
tenacity and elongation at break of a co~posite
polyesterlviscose spun yarn according to the present
invention to a combed Egyptian cotton yarn.
". ....
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W092/062~ 0 9 ~ 8 ~ ~ - 12 - PCT/US91/07320
TA~
~_. . _ ........... . _
¦ Example Metric Twists per Tenacity,* Elonga-
l Numbers unit cN/tex tion,
i twlsts; percent
¦ __ meter
1 34 619 26.0 12.0
ICo~para- 34 32.0 16.0
5tive A
_
Compara- 34 23.0 10.8
¦tive B
I .__ .
ICompara- 34 16.0 7.0 - -
¦tive C -- ~
l _ .. . .
ICompara- 34 651 20.8 11.1
tive D
2 40 690 25.0 11.8
I _
Compara- 40 725 20.0 10. 6
¦tive D-2
1 3 so --- 801 23.0 11.5
Compara- 50 841 19.5 10.5
Itive D-3 .
* yarn conditioned at about 65 percent relative
humidity and at a temperature of about 20C
E~op~ a 4-6
Examples 4 to 6 illustrate the preparation of a woven
fabric accordi~g to the present invention. The weight of
the woven fabric was in the range ~rom about 160 to about
200 g/m2, which corresponds to what is conventionally known
as J-type wov~n fabric (i.e., "jean"). The weave of the
- woven fabric was armored serge (i.e, drill weave~ t2/1).
The warp yarn used to prepare Examples 4 to 6 was a
polyester/rayon spun yarn (P/R) comprising abaut 50
:
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209188~
W092/06232 - 13 - PCT/US91/07320
percent by weight polyester fibers ("TERGAL Tlll FI~ERS")
and about 50 percent by weight spun staple rayon fibers
("LENZING MODAL HIGH TENACITY FIBERS").
The weft yarn for Examples 4-6 was either the
polyester/rayon spun yarn used as the warp yarn or a yarn
comprising American cotton (A-cotton) fibers (commercially
available from Perrin of Cornimont, France). Prior to
weaving the yarns, the warp yarns were sized by a
conventional si~ing means, wherein the warp yarns were
impregnated by passing them through an aqueous-based bath
which left a superficial deposit around the composite
yarn. The aqueous-based bath comprised about 100 parts
water, 4 parts carboxymethylcellulose-polyvinyl alcohol
(commercially available under the trade designation "ROTTA
989" from Rotta Ltd.) in about 2 parts
carboxymethylcellulose (commercially available under the
trade designation "CMC P 400" from Sopatis Ltd.). The
temperature of the aqueous-based bath during the sizing -
was in the range from about 75-85C.
The fabrics of Examples 4 to 6 were prepared from the
yarns using conventional weaving methods. The metric
numbers of the yarns used and the number of threads per
unit length are listed in Table 2, below. -
Comparatives E, F, and G were prepared as described
above for Examples 4 to 6 except the warp and weft yarns
werQ comprised of Egyptian cotton (E-cotton) fibers (from
Hoffe). The metric nu~er of the fibers used to prepare -` -
the comparative examples and the number of threads per
unit area are listed in Table 2 below.
The tensile strength in both the warp direction and
the weft direction of the fabrics of Examples 4 to 6 and ;
the comparative Examples E, F, and G were measured using a
conventional tensile tester ~commercially available under
the trade designation "LLYOD TYPE M5K" from Lloyd
InstrumQnts of South Hampton, UX). Each fabric tested was
conditioned at about 65 percent relative humidity and at a
temperature of about 20C. The sample width was about
50+0.5 mm. The distance between the jaws was about 200+1
,','.
.
. .
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wo 92'06222o 9 1 8 8 4 - 14 - PCT/US91/07320
mm. The speed was about 100 mm/minute. The load for the
elongation test was about 90 daN/5cm. The results are
listed in Table 2 below.
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W O 92/06232 2 0 918 8 4 PC~r/US91/07320
o ~ o o o o
e
3 u ` u~
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1 ~0~ o o o ~ ,,
e ~ 3 u ~ ~ a
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~ 1~
3 ~ 1 c c o c l . ~
~ ~ U
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w092/06 ~ ~ 9 1 8 ~ ~ - 16 - PCT/VS91/07320
To reduce the water retention of the yarns comprising
the fabrics of Examples 4 to 6, which increases the
elongation of the fabric, each sample was stretched in an
aqueous-based bath as follows.
The aqueous-based bath comprised about 1000 parts
water, about 175 parts of a brown-black dye agent
(commercially available under the trade designation
"CORIACIDE" from ICI Ltd.) and an alkylphosphate-based
wetting agent. The temperature of the aqueous-based bath
was about 75-85C.
Each fabric was passed through the aqueous-based bath
under a linear tension of about 1.5 kilograms per
centimeter. The ~abric was then dried on a heating
cylinder at a temperature of about 175C.
A presized material was then coated the weft yarn
face each fabric. The presized material was derived from
a resin formulation comprising 150 parts of a
thermohardening resin (phenol formaldehyde type at 50
percent solids) about 850 parts of a styrene/butadiene-
based latex, about 2 parts of a silicon-based antifoaming
agent, and about 11 parts of a anionic emulsion thickening
agent. The viscosity of the presize formulation was about
3500 to about 5000 cps. The presize formulation was
coat~d onto the weft yarn face to provide a quantity
suSficient to allow front filling of the fabric. The
coated presize was dried at a temperature of about 135C
and provid~d an average add-on weight to each fabric of
about 50+5 gjm2.
The warp face of each Sabric was then coated with a
backsize matQrial derived from a formulation comprising
about I0,000 parts of a styrene/butadiene-based latex,
about 20 parts of a silicon-based antifoam agent, and
about 3 part~ of a dye agent (commercially available under
the trade designation "CHLORAZOL BLUE GD LIQUID" from
I.C.I. Ltd.).
The backsize formulation was coated onto the warp
face of each fabric. The backsize formulation was dried
.
2091884
W092/06232 - 17 - PCT/US91/07320
in a temperature of about 100C and provided an average
dry add-on weight of about 18 to 22 g/m2.
The weight per unit area of presized and backsized
Examples 4 and 5, when conditioned at zero percent
relative humidity and at a temperature of about 200C, was ~ -
about 257 and about 253 y/m2~ respectively.
The tensile strength of presized and backsized
Examples 4 and 5 in the warp and weft direction were
determined as described above. The tensile strength of
presized and backsized Examples 4 and 5 in the warp
direction were about 170 and about 120 daN/5 cm,
respectively. The tensile strength of presized and
backsized Examples 4 and 5 in the weft direction was about
75 and about 50 daN/5 cm, respective~y.
The elongation at break of presized and backsized
Examples 4 and 5 was measured in the warp direction as
described above. The elongation at break of presized and
backsized Examples 4 and 5 in the warp direction was about
6.5 daN/5 cm.
Various modifications and alterations of this
invention will become apparent to those skilled in the art
without departing from the scope and spirit of this -
invention, and it should be understood that this invention
is not to be unduly limited to the illustrative
em~odiments ~et ~orth herein.
', . .
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