Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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TITLE
A Process for Flash Spinning Fiber-Forming Polymers
10
FIELD OF THE INVENTION
The invention relates to a process for
flash-spinning plexifilamentary film-fibril strands of
polymers that are substantially plasticizable in carbon
dioxide and/or water, and have a mealting point less than
300°C. More particularly, the invention relates to
plexifilamentary film-fibril strands that are flash-spun
from mixtures~of carbon dioxide, w<~ter and the polymer.
BACKGROUND OF THE :INVENTION
Blades and White, United States Patent
3,081,519 describe flash-spinning plexifilamentary
film-fibril strands from fiber-forming polymers. A
solution of the polymer in a liquid, which is a
non-solvent for the polymer at or below its normal
boiling point, is extruded at a temperature above the
normal boiling point of the liquid and at autogenous or
higher pressure into a medium of lower temperature and
substantially lower pressure. This flash spinning
causes the liquid to vaporize and ithereby cool the
exudate which forms a plexifilamenitary film-fibril
strand of the polymer. According ito Blades and White,
the following liquids are useful in the flash-spinning
process: aromatic hydrocarbons such as benzene, toluene,
etc.; aliphatic hydrocarbons such <~s butane, pentane,
.hexane, heptane, octane, and their isomers and homologs:
TK-2775-B _1_
alicyclic hydrocarbons such as cyclohexane; unsaturated
hydrocarbons; halogenated hydrocarbons such as methylene
chloride, carbon tetrachloride, chloroform, ethyl
chloride, methyl chloride: alcohols; esters; ethers;
ketones; nitriles; amides; fluorocarbons; sulfur
dioxide; carbon disulfide; nitromethane; water; and
mixtures of the above liguids. The patent further
states that the flash-spinning solution additionally may
contain a dissolved gas, such as nitrogen, carbon
dioxide, helium, hydrogen, methane, propane, butane,
ethylene, propylene, butene, etc. Preferred for
improving plexifilament fibrillation are the less
soluble gases, i.e., those that dissolve to a less than
7% concentration in the polymer solution under the
spinning conditions.
Blades and White state that polymers which may
be flash spun include those synthetic filament-forming
polymers or polymer mixtures which are capable of having
appreciable crystallinity and a high rate of
crystallization. A preferred class of polymers is the
crystalline, non-polar group consisting mainly of
crystalline polyhydrocarbons, such as polyethylene and
polypropylene.
U.S. Patent 3,169,899 lists polyester,
polyoxymethylene, polyacrylonitrile, polyamide,
polyvinyl chloride, etc. as other polymers that may be
flash spun. Still other polymers mentioned in the
patent are flash spun as mixtures with polyethylene,
including ethylene vinyl alcohol, polyvinyl chloride,
polyurethane, etc. Example Z8 of U.S. 3,169,899
illustrates flash spinning from methylene chloride of a
mixture of polyethylene and ethylene vinyl alcohol in
which polyethylene is the predominant component of the
polymer mixture. '
Flash spun polyethylene products have achieved
considerable commercial success. "Tyvek~" is a
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spunbonded polyethylene sheet product sold by
E, I: du Pont de Nemours and Company. These sheets are
used in the construction and packaging industries.
"Tyvek~" is also used in protectime apparel since the
flash spun product provides a good barrier to
particulate penetration. However, 'the hydrophobic nature
of polyethylene results in a garment which tends to be
uncomfortable during hot, humid weather. A more
hydrophilic flash spun product is clearly desirable for
garment and some other end uses. Additionally, flash
spinning of any of the polymers would preferably be
achieved from an environmentally safe, non-toxic
solvent.
. Trichlorofluoromethane (Freon-11) has been a
very useful solvent for commercial manufacture of
plexifilamentary film-fibril strands of polyethylene.
However, the escape of such a halocarbon into the
atmosphere has been implicated as a serious source of
depletion of the earth's ozone. A. general discussion of
the ozone-depletion problem is presented, for example by
P.S. Zurer, "Search Intensifies for Alternatives to
ozone-Depleting Halocarbons", Chemical & Enctineerinct
News, pages 17-20 (February 8, 1988). The substitution
of environmentally safe solvents for
trichlarofluoromethane in a commercial flash spinning
process should minimize the ozone depletion problem.
There now has been discovered in accordance
with this invention, flash spun polymer products
desirable for uses such as garmenta, construction and
packaging, which are flash spun from an environmentally
acceptable mixture comprising carbon dioxide and water.
SUMMARY OF THE IN~~ENTION
There is provided by this invention a process
for flash spinning plexifilamentary film-fibril strands of a
polymer that is substantially plast:icizable in carbon dioxide or
water and has a melting point less than 300 °C, comprising: the
steps of
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(a) forming a spin mixture of water, 30 to 90% carbon
dioxide based on the total weight of the spin mixture and a
polymer selected from the group consisting of graft
copolymers of ethylene vinyl alcohol and polyolefin,
polyurethane, graft copolymers of acrylic acid, and
'mixtures of at least one of these polymers with polyolefin,
at a temperature of at least 130 °C and a pressure that is
greater than the autogenous pressure: of the mixture; and
(b) then flash spinning the mixture: into a region of
substantially lower temperature and pressure.
Preferably, the polymer is a polyolefin
selected from the group consisting of polyethylene,
polypropylene, ethylene vinyl alcohol copolymers and
combinations thereof. An especially desirable
combination is polyethylene with elthylene vinyl alcohol
to which is grafted about 10% by weight of a high
density polyethylene.
As used herein, the terms "substantially
plasticizable" mean that the polymers are softened and
become less viscous by,imbibbing t;he carbon dioxide
and/or water. ,
DETAILED DESCRIPTION OF THE PREFFERED EMBODIMENTS
The term "plexifilamentary film-fibril strand"
or simply "plexifilamentary strand", as used herein,
means a strand which is characterized as a
three-dimensional integral network. of a multitude of
thin, ribbon-like, film-fibril elements of random length
and of less than about 4 microns average thickness,
generally coextensively aligned with the longitudinal
axis of the strand. The film-fibril elements
intermittently unite and separate at irregular intervals
in various places throughout the length, width and
thickness of the strand to form tree three-dimensional
network. Such strands are described in further detail
by Blades and White, United States Patent 3,081,519 and
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by Anderson and Romano, United States Patent 3,227,794.
Polymers particularly useful in the practice of
this invention are polyethylene, polypropylene, grafted
and ungrafted copolymers of ethylene and vinyl alcohol
(hereinafter sometimes referred to as °~EVOH°°), graft
copolymers of acrylic acid, polyurethane, and
combinations thereof. The copolymers of ethylene and
vinyl alcohol have a copolymerized ethylene content of
about at least 20 mole%. The ethylene vinyl alcohol
copolymer may include as an optional comonomer other
olefins such as propylene, butene-1, pentene-1, or
4-methylpentene-1 in such an amount as to not change the
inherent properties of the copolymer, generally in an
amount of up to about 5 mole%, based on the total
copolymer. The melting points of these ethylene vinyl
alcohol polymers are generally between .about 160 and
190°C. Ethylene vinyl alcohol polymers are normally
prepared by copolymerization of ethylene with vinyl
acetate followed by saponification of the acetate groups
to the hydroxyl groups., At least about 90% of the
acetate groups should by saponified, this being
necessary to achieve~sufficient mixing of the polymer.
This process is well known in the art.
A particularly advantageous EVOH polymer can be
prepared by grafting long chains of polyethylene or
polypropylene (i.e., blocks), onto the random ethylene
vinyl alcohol copolymer. The grafting process is
accomplished by properly mixing EVOH and a pendant
anhydride containing polyolefins in the molten state
under shear through either a batch or continuous mixing
device (e. g., haake mixer or extruder). The grafted
polymers appear to be more compatible with additional
polyolefins used in most of the flash spinning
experiments. A polyolefin graft level of 5-50% by weight
is most useful.
The process requires forming a spin mixture of
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the polymer, water and carbon dio~:ide. The water is
present in the range from 5 to 50 percent based on the
total weight of the spin mixture. The carbon dioxide is
present in the range from 30 to 90 percent based on the
total weight of the spin mixture. The polymer is
present in the range from 1.5 to 25 percent based on the
total weight of the spin mixture.
As noted above, the spin mixture may also
comprise ethylene vinyl alcohol copolymer and an
additional polymer presQnt in the range from 0 to 25
percent based on the total weight of the spin mixture.
Conveniently, polyethylene and polypropylene are the
preferred additional polymers.
The spinning mixture may optionally contain x
surfactant. The presence of such a surfactant appears
to assist in emulsifying the polymer, or in otherwise
aiding in forming a mixture. Examples of suitable
nonionic surfactants are disclosed in U. S. Patent No.
4,082,887.
Among the suitable, commercially
available, nonionic: surfactants a:re the " SpansTM" , which
are mixtures of the esters of the monolaurate,
monooieate and monostearate type and the "TweensT~", which
are the polyoxyethylene derivatives of these esters.
The "SpansT~" and the "TweensT~" are products of
ICI Americas, Wilmington, DE.
The required temperatures for preparing the
spin mixture and for flash-spinning the mixture are
usually about the same and usually are in the range of
13o to 275°C. The mixing and the flash-spinning are
performed at a pressure that is higher than the
autagenous pressure of the mixture. The pressure during
the spin mixture preparation is generally in the range
from 1,200 to 6,000 psi.
Conventional flash-spinning additives can be
incorporated into the spin mixtures by known techniques.
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These additives can function as ultraviolet-light
stabilizers, antioxidants, fillers, dyes, surfactants
and the like.
EXAMPLES
Eauipment
Two autoclaves were used in the following
non-limiting examples. One autoclave, designated a
"300cc" autoclave (Autoclave Engineers, Inc., Erie, PA)
was equipped with a turbine-blade agitator, temperature
and pressure measuring devices, he<~ting means, a means
of pumping in carbon dioxide under pressure and inlets
for loading the ingredients. An exit line from the
bottom of the autoclave was connected through a
quick-acting valve to a spin orifice 0.079 cm in
diameter. The spin orifice had a length to diameter
ratio of 1 with a tapered conical entrance at an angle
of 120 degrees. The second autoclave, designated a "1
gallon" autoclave (again made by Autoclave Engineers,
Inc.), was equipped in an analogous manner to that of
the "300cc" autoclave.
Test Procedures
The surface area of the plexifilamentary
film-fibril strand product is a measure of the degree
and fineness of fibrillation of the flash-spun product.
Surface area is measured by the BET nitrogen absorption
method of S. Brunauer, P.H. Emmett and E. Teller,
Journal of American Chemical Socie~, Vol. 60, pp.
309-319 {1938) and is reported as m2/g.
Tenacity and elongation o~f the flash-spun
strand are determined with an InstronT" tensile-testing
machine. The strands are conditioned and tested at 70'F
and 65% relative humidity. The strands are then twisted
to 10 turns per inch and mounted i.n the jaws of the
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Instron'~' Tester. A 1-inch gauge length and an elongation
rate of 60% per minute are used. The tenacity at break
is recorded in grams per denier (gpd)~
The denier of the strand :is determined from the
weight of a 15 cm sample length of strand.
Tn the non-limiting examples which follow, all
parts and percentages are by weight unless otherwise
indicated. The conditions of all :Examples are
summarized in Table I.
Example 1
The "300 cc" autoclave was loaded in sequence
with 7 g of an ethylene vinyl alcohol copolymer, 43 g
crushed ice and 50 g crushed solid carbon dioxide. The
copolymer contained 30 mole% ethylene units, had a melt
flow rate of 3 g/lOmin by standard techniques at a
temperature of 210°C and a pressure of 2.16 kg, a
melting point of 183°C and a density of 1.2 g/cc. The
resin was a commercially available, product from
E. I. du Pont de Nemours and Company, Wilmington,
Delaware sold as SELAF~ 3003.
The autoclave was closed and the vessel was
Pressurized to 850 psi (5861 kPa) with liquid carbon
dioxide for 5 minutes while stirring until the mixture
reached room temperature (24°C). The amount of carbon
dioxide added was then obtained from the difference of
volumes (the densities of the polymer (1.2 g/cc), water
(1.0 g/cc) and liquid carbon dioxide (0.72 g/cc) at 24°C
assuming complete filling of the autoclave. The amount
of carbon dioxide added to this point was 166 g. The
stirrer was rotated at 2000 rpm, amd heating was begun.
When the temperature of the contents of the autoclave
reached 175°C, the internal pressure was adjusted by
venting approximately 10% of the carbon dioxide and 10%
of the water to reduce the pressure to 2500 psi (17,238
kPa). The spin mixture, after venting, contained 3.6%
_g_
~:~~~~ ~'
_g_
ethylene vinyl alcohol copolymer, 19.8% water and 76.6%
carbon dioxide as shown in Table I. The stirring was
continued for 30 minutes at a temperature of 175°C and a
pressure of 2500 psi. Agitation was stopped followed by
prompt opening of the exit valve to permit the mixture
to flow~to the spin orifice which also had been heated
to 175°C. The mixture was flash spun and collected.
Scanning Electron Microscopy (SEM) revealed a
finely fibrillated continuous plexifilamentary strand.
The strand was noticably elastomeric and had recovery
properties.
Example 2
The procedure of Example 1 was followed except
that an ethylene vinyl alcohol copolymer was used with
44 mole% ethylene units. The 44 mole% copolymer was
obtained from E. I. du Pont de Nemours and Company,
Wilmington, Delaware as SELAI"~8 4416. It had a melt flow
rate of 16 10 min 210°C, 2.16 k ) a meltin
g/ ( g g point of
168°C and a density of 1.15 g/cc. The result as
determined by SEM was,a finely fibrillated
plexifilamentary strand. The strand was noticably
elastomeric and was similar in appearance to the strand
of Example 1.
xample 3
The procedure of Example 2 was followed except
that the spin pressure was 2550 psi. The result again
was an elastomeric plexifilamentary strand. SEM
analysis showed the strand to be coarser than the strand
of Example 2.
Example 4
The procedure of Example 1 was followed except
that the polymer concentration was increased and the
spin pressure was 3300 psi. The result was~a strand
_g_
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similar to that of Example 3.
' Examine 5
The procedure of Example 1 was followed except
that the spin pressure was 3500 psi and 0.5%, based on
the total weight of the spin mixture, high density
polyethylene (HDPE) was added to the mixture. The
polyethylene used has a melt index of ca. 0.8, and is
commercially available from Occidential Chemical
Corporation of Houston, Texas.as ALATHO~ 7026A. The .
result was a high quality finely fibrillated
plexifilamentary strand. The strand was elastomeric but
less so than the strand of Example 1.
Example 6
The procedure of Example 5 was~followed eXCept
that the amount of polyethylene was increased. The
result as determined by SEM was a continuous finely
fibrillated strand of slightly more coarse fibrillation
than the strand of Example 5. The: strand showed a
further loss in elastomeric properties over the strand
of Example 5.
Example 7
The procedure of Example 5 was followed except
that the amount of polyethylene w<~s further increased.
SEM analysis revealed a coarse plexifilamentary strand.
The strand had no elastomeric properties.
_Example 8
The procedure of Example 1 was followed with
the various component changes as ahown in Table I. In
this example, 2 g of a nonionic surfactant mixture
containing 65% by weight ~~SpanTM" 80 and 35o by weight
"TweenTM" 80 was added to the spin mix. The autoclave was
not vented in this example, but was allowed to reach the
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~~,'~;~,'~'~
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spin pressure by heating and holding the temperature at
177°C. The result was a continuous, somewhat coarsely
fibrillated mat of plexifilamentary fibers. The fibers
were elastomeric.
Example 9
The procedure of Example 8 was followed with
the various component changes as shown in Table I. The
result was a strand similar to that of Example 8.
Example 10
The procedure of Example 1 was followed with
the various component changes as shown in Table I. The
result was a plexifilamentary yarn of very fine,
continuous white fibers.
Example 11
The procedure of Example 5 was followed except
that linear low density polyethylene (LDPE) was used
instead of high density, polyethylene, as shown in Table
I. The linear low density polyethylene (melt index of
25) is sold commerciallx by Dow Chemical Corp., Midland,
Michigan as Aspurl~ 6801. The result was fine,
discontinuous plexifilamentary fibers 1/4 to 1/2 inch in
length.
Example 12
The "1 gallon" autoclave was loaded with 600 g
ASPUI~ 6801 and 700 g water, then the vessel was closed.
The exit manifold of the autoclave was Pitted with a
spin orifice of 0.035" with a tapered conical entrance
at an ang7.e of 120 degrees. A vacuum educator was used
to pump the vessel to 20 i». mercury pressure for 15
seconds to remove most of the air but not to
significantly remove water. The vessel was then
pressurized with carbon dioxide until 1500 g of carbon
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w
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dioxide had been added, the amount measured with a
"Micro-motion" mass flow instrument. Agitation was begun
and set to 1000 rpm. Heating of the vessel was begun and
continued until the goal temperature of 170°C was
reached. Pressure was adjusted by bleeding small amounts
of vapor until the pressure stabilized at 4,500 psi. The
mixture was held at 170°C for 1 minute, the agitator
slowed to about 250 rpm and the exit valve promptly
opened to permit the mixture to flow to the spin.
orifice, which had been heated to 210°C. The result was
the formation of a finely fibrillated continuous yarn.
Example 13
The procedure of Example 12 was used except
that the autoclave was loaded with 300 g ASPU1~ 6801,
125 g Sela~ OH 4416 ethylene/vinyl alcohol copolymer of
melt index 16 (E. I. du Pont de Nemours and Co.,
Wilmington, Delaware), 840 g water, and was charged with
1~p0 g carbon dioxide. Spinning gave a finely
fibrillated continuous.yarn very much like that of
Example 1 except the yarn is more hydrophilic and has
some elastic recovery properties.
Examp~.e 14
The "300 cc" autoclave was used and operated in
the same manner as the "1 gallon" autoclave. Through an
addition port, the autoclave was loaded with 30 g
Alathor8(~/7050 high density linear polyethylene, melt
index 17'.5, (Occidential Chemical Corporation, Houston,
Texas) and 56 g water. Most of the air was removed from
the autoclave by brief evacuation to 20 in. mercury.
The autoclave was then pressurized with 146 g carbon
dioxide, the agitator set to 2000 rpm and heating begun
up to a goal temperature of 170°C. When the goal
temperature was reached, the pressure was adjusted by
venting small amounts of the mixture to give 4,500 psi.
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~~~,~4 ~ ~'
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The mixture was then agitated an additional 15 minutes.
The exit valve was opened and the mixture spun through
the spin orifice. The result was a pulp consisting of
finely fibrillated fibers of high quality, ranging from
1/16 to 2 inches in length. The fibers are useful far
formation of sheet structures made by known paper making
processes.
Example 15
The procedure of Example 14 was followed
except the autoclave was charged with 15 g Sela~ OH
4416 resin, 15 g ASPUN~ 6801 resin and 56 grams of
water. The autoclave was then pressurized with 146 g
Carbon dioxide. Pressure was 4,700 psi at spinning. A
very finely fibrillated continuous yarn, soft and with
fibers that are easily separated from the yarn bundle,
was produced.
Example 16_
The procedure,of Example 14 was followed,
except the autoclave was charged with 30 g ASPUi~ 6801
resin, 15 g Sela~ OH 4416 resin, and 56 g water, and
was pressurized with carbon dioxide to a pressure of
3700 psi 'at spinning. The result was a continuous,
finely fibrillated continuous plexifilamentary yarn.
example 17
The procedure of Example 12 was followed,
except the autoclave was loaded with 500 g ASPU1~ 6801
resin, 100 g SELAR~ OH 4416 resin, 700 g water and 1300
g carbon dioxide; then the autoclave was heated at 170'C
to a goal pressure of 5,500 psi. The agitator was
changed to a multiple high shear paddle/turbine design.
High quality continuous finely fibrillated yarn was
produced that gave a twisted break tenacity of 1.45
g/denier at 38% elongation.
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Example 18
Example 17 was re-run under the same conditions
but the spinning temperature was increased to 180'C.
The yarn was essentially equivalent to Example 17 and
measured 1.72 g/denier tenacity at: 38.7% elongation.
Surface area was measured by the nitrogen absorption
technique to be 4.44 m2/g~
Example 7.9
The procedure of Example 1 was followed, except
that the charge consisted of 4 g ~'funtsman 7521TM
polypropylene (Huntsman Polypropylene Corp., Woodbury,
New,Jersey), an injection molding grade homopolymer of
melt flow 3.5 g/l0 minutes and melting point of 168'C, 6
g Sela~ OH 4416 ethylene vinyl alcohol copolymer, 43 g
ice and 50 g crushed solid carbon dioxide (i.e., dry
ice). The autoclave was heated to a goal temperature of
1~5.C, a pressure of 3,500 psi and agitated at 2,000 rpm
for l5 minutes. When the discharge valve was opened, a
mass of discontinuous,;.coarsly fibrillated fibers was
obtained. ,
Exam~2 0
The procedure of Example 19 was followed except
that the autoclave was charged with 10 g Sela~ OH 4416
resin, 4 g Huntsman 7521TM polypropylene resin, 43 g .ice
and 50 g crushed solid carbon dio:Kide. A finer
fibrillated semi-continuous mass of fibers was made.
Exa~21
The procedure of Example 12 was followed except
that the autoclave was loaded with 300 g Alathor~ 7050,
100 g of "E64179-124-1" (a ethylene vinyl alcohol
copolymer to which has been grafted about 10% by weight
high density polyethylene), 1200 ~g carbon dioxide and
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500 g distilled water. A slotted spinning nozzle
designed to produce a flat rather than cylidrical web
shape was used. The goal temperature was 175°C.
Otherwise, the procedure was the same as Example 12. The
result was the formation of a finely fibrillated
continuous yarn that had a twisted tenacity of 4
g/denier, an elongation of 46% and a surface area of 13
m2/g as measured by the BET method.
"E64179-124-1" is not a commercially available
product. It is prepared by taking SELAF~ OH 4416 and
modifying it through in situ grafting with high density
polyethylene resin that has itself been modified. The
high density polyethylene resin ways modified in a twin
screw extruder through the controlled addition of a -
peroxide initiator and malefic anhydride. The modified
resin is referred to as "HDPE-G-MAN" (high density
polyethylene grafted by malefic anhydride addition). The
SELAF~ OH 4416 was modified through in situ grafting
with the "HDPE-G-MAN" at about 10% by weight in a twin
screw extruder at 220°C. The anhydride/hydroxyl reaction
provides the grafting;site to chemically link up the
HDPE and the EVOH.
Example :>2
The procedure of Example 21 was followed
except that 380 g Alatho~/?050 and 20 g of
"64179-124-1" was used. The resuli~ was essentially the
same as Example 21 except that the resulting yarn was
much less hydrophilic and hand sheets made from the yarn
exhibited bonding characteristics more like that
expected of pure polyethylene yarn.
Example 23
The procedure of Example 22 was used except
that into the autoclave were loaded 300 g of Shell PP
WRS5-675TM (polypropylene polymer commercially available
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l~ ~Dy P1
~9 ;a:l'~..f
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from Shell Chemical Company, Short Hills, New Jersey),
100 g of "69179-124-5" (a ethylene vinyl alcohol
copolymer as described in Example 21 except that to
which has been grafted about 20% polypropylene by
weight), and 1555 g carbon dioxide. The goal temperature
was 200°C. A finely fibrillated 20 inch wide swath was
produced that was slightly more coarse that seen when
polyethylene was the polymer.
Example 24
The procedure of Example 22 was used except
that 300 g of "HTX-6133" (a melt spinnable polyurethane
polymer (a butylene/poly (alkylene ether) phthalate)),
120~g Alathor~/7050 high density polyethylene and 1715~g
carbon dioxide were loaded into the autoclave. The goal
temperature was 180°C. A very finely fibrillated yarn
was produced with a unique "silky" feel and elastomeric
properties.
~ HTX-6133 is a very soft HYTREI~ resin
comprised of 77 wt.% soft segment and 23 wt.% hard
segment. It is specif$cally described in the Examples
(Preparation of Elastomer A) in U.S. Patent 4,731,407
(Benim et al.), the entire contents of which are
incorporated by reference herein. ~ ~
Example 25
The procedure of Example 7.4 was used except
that the autoclave was loaded with 15.5 g of Sela~ 4416
ethylene~vinyl alcohol copolymer of melt index 16
(commercially available from E.I. du Pont de Nemours and
Company, Wilmington, Delaware), 15.5 g of Polybonc~ 1011
acrylic acid graft copolymer with polypropylene of melt
index 20 (commercially available from British Petroleum
Chemicals, Hackettstown, New Jersey), 49 g distilled
water and 120 g carbon dioxide. The mixture was stirred
at 200°C and 5000 psi pressure for 15 minutes prior to
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~',o E"'~~lr~p~9
~Z~~ar~s~aa...~: ~Iv..y
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spinning through a 0.0031 inch spin orifice. A well
fibrillated, continuous plexifilamentary yarn was
produced.
TABLE ~.
%Additional %Sur- Spinninc
Example %EVOH Polyolefinfactant%H20 %C02 TC Pfpsi)
#
1 3.6 0 0 19.8 76.6 175 2500
2 3.6 0 0 19.8 76.6 175 3250
3 3.6 0 0 19.8 76.6 175 2550
4 7.1 0 0 19.6 73.3 175 3300
5 3.6 0.5 HDPE 0 19.8 76.1 175 3500
6 3.6 1.0 HDPE 0 19.7 75.7 175 3500
7. 3.0 2.1 HDPE 0 19.7 75.2 175 3500
g 4.4 . HDPE 0.9 34.9 59.4 177 3100
0.4
9 8.7 0 0.9 35.0 55.4 173 1700
10 9.6 0 0.1 34.7 55.6 152 4900
11 7.1 2.0 LDPE 0 19.5 71.4 175 2500
12 0 21.4 LDPE 0 25.0 53.6 170 4500
13 4.2 10.1 LDPE 0 28.3 57.3 170 4500
14 0' 12.9 HDPE 0 23.2 62.9 170 4500
- 15 6.5 6.5 LDPE 0 24.1 62.9 170 4700
16 0 12.9 LDPE 0 23.2 62.9 170 3700
17 3.8 19.2 LDPE 0 26.9 50.0 170 5500
18 3.8 19.2 LDPE 0 26.9 50.0 180 5500
19 5.8 3.8 PP 0 41.7 48.5 175 3500
'
20 9.3 3.7 'PP 0 40.2 46.7 175 3500
21 4.8 14.3 HDPE 0 23.8 57.1 175 4500
22 1.0 18.1 HDPE 0 23.8 57.1 175 4500
23 4.1 12.2 PP 0 20.4 63.3 200 4500
24 11.4* 4.6 HDPE 0 19.0 65.1 180 4500
25 7.8 7.8 PP/AA0 24.5 60.0 200 5000
HDPE= high density polyethylene
LDPE= low density polyethylene
PP= polypropylene
AA= acrylic acid
* Polymer used was polyurethane and not EVOH
Although particular embodiments of the present
invention have been described in the foregoing description,
it will be understood by those skilled in the art that the
invention is capable of numerous modifications,
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at r rL..rai~~~.a
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spirit or essential attributes of the invention. Reference
should be made to the appended claims, rather than to the
foregoing specification, as indicating the scope of the
invention.
1.0
20
30
-18--
