Note: Descriptions are shown in the official language in which they were submitted.
CA 02262364 1999-01-26
9GB042.PCT , .
POLYOLEFIN/FILLER FILI\~S HAVING INCREASED WVTR AND
METHOD FOR MAKING
TEC~NTCAL F~ELD
This invention relates generally to polyolefin films having greatly increased
WVTR and methods of making same. More specifically this invention is directed
toward filled polyethylene films having increased WVTR at a given filler loading,
and a given set of process conditions.
BACKGROUND
Preparation of films having good WVTR from highly filled polymers,
usually polyolefins, are known. In the past a combination of a polyolefin, usually a
polyethylene, with a filler, usually CaCO~, while very useful and widely used as a
film with good WVTR, usually in combination with non-woven polymers (for use
in diapers, adult incontinence devices, feminine hygiene articles, housewrap
composites, roofing materials and the like), have had some limitations that werewell known in the industry.
Among these limitations are a practical limitation in thickness (also
expressed as basis weight) in that conventional Ziegler-Natta catalyzed polymers,
more specifically linear low density polyethylene (LLDPE) highly filled film
formulations could not generally be drawn down below 76.2 ~am (3 mils). The
most obvious problem with such a limitation is that the user of the film could not
make a product utilizing a lower thickness film, meaning that the cost of the film
(usually sold on a weight basis) might have been higher than the application
necessitated. A less obvious issue is that at lower thicknesses, for the same density
resin at the same filler loading, the product would be relatively softer than higher
thicknesses, an attribute of importance in any article that comes in contact with
humans, such as apparel.
Another limitation of previous polyethylene/filler films is that for a given
filler loading, with conventional Z-N catalyzed polyethylene resins, is WVTR,
limited (on the upper end) by the amount of post-extrusion orientation that could
be practically achieved. Additionally, the imperfections often found in conventional
A~EN0ED SHFET
CA 02262364 1999-01-26
WO g8/OSSOl PC rluS9 7/13578
- 2 -
Z-N resins and films, such as gels, made rcz~ .ng and ~ ining a high rate of
prothlction Aiffi~-lt, and a high level of orientation might often lead to breaks,
holes, or tear offs in the film leading to lower prime production rates.
Yet another limit~tio~ of the conve~ n~l Z-N filled and ~;e~led films is
related to both WVTR and production rates. Spe~;r.e~lly, with a given
conv~o~ntiQn~l filled polyethylene, to attain a certain WVTR, a certain filler loading
had to be used. In general, within limits, the higher the filler loaflir~ the more
~1ifficl~lt to process ( the above referenced production problems such as large void
clealiol~ and tear offs are exacerbated by a higher filler loading, as the film maker
seeks to maximize production rates).
US 4,777,073 suggests a permeability and sllellglh of polyethylene/filler
~",I)ill&lions may be attained by co...h;~ 8 a LLDPE described as being made
using a Zeigler-Natta or chromium catalysts, with fillers such as CaCO3 present in
the LLDPE from 15 to 35 percent by volume which is equivalent to 34-62% by
1 5 weight.
There is a commercial need therefore for a polyethylene filler combination
that will give a higher WVTR at a given filler lo~ding, at an equivalent thicl~n~s~.
There is a similar need for a polyethylene filler con,b;nalion that can deliver
equivalent WVTR at lower filler loadings and can be made at a lower basis weight,
than a conventional Z-N polyethylene/filler combination.
SUMMARY
We have discovered that making a film from a polyethylene/filler
co,.lbh~alion using a metallocene catalyzed polyethylene, surprisingly and
u~ e iledly provides the ability to achieve a substantially higher WVTR (at
colnl)al~ble filler loading and thickness), a lower thickness (or basis weight) (at
col..palable filler loading and orientation), and can achieve an equivalent WVTR at
lower filler loadings (improving processability) when compared to conventional Z-
N polyethylene/filler co...bi~ ion.
The metallocene catalyzed polyethylenes (m-polyethylene) will have a
molecular weight distribution (defined as the ratio of weight to the number average
molecular weight Mw/Mn) generally less than 3, preferably less than 2.5.
CA 02262364 1999-01-26
" ,,"~ ;3.!"-U'~3 ,,~' 3;''!~ 3~ ,, +~ >;~<)~3~ ;5:J/ r~
96~04~.PCr 3
lhe dr~wdowll of a filled m-po~ethyle~le will ~e sn~re than 10, pTef~rably
more tha~ 20, more pre~.bly ~re ~h~n 30 perce~t less tha~ the uh~ste
~awdo~n o~' a fiL~d Z-N po~ yl~c, where the relatio~ship in the filled Z-N
polye~hylene between the filler ~mounl ~md bass we~ht (~ .) for film~
fo~ow thc general equa~ion:
W = Z. 10 + 0.380 (weig~t % CaCO;)
w~ere W is ~he .,. ~;~ basis wei~ht m gfm2 in the film
The rela~ionship is at co~stant draw (o~ ;hn tra~sverse ~ uon or
TD) of 2.7:1, 7;~e speed 103.6 meters per ~ute (ml~m) ~340 feet) per cu:te
t~m). For m-po~ Ien~ filled fn~ 19 shc followmg gene~al equ~i
apphe~:
W = ~.07 + 0.207 (wei~ht % CaCO~)
,~iA~nn~ny the water vapor trm~ n rate (WVTR) of a filled ~
po~e~le~le is as least 10 perce~t greatet, pf~ .b~ at least 20 perc~t, more
1~ prefèrably ~t least 3~ pa~Lt gre~er t~ 3 filled Z-N pok~e~ylene, lt ~e same
fi~er loadillg ~Qd th ;~ ight), wh~e the ZN polyethylene~fiiler
WVTR is d~ y the eqU~nt~n
WVTR = -10,900 + 320 (weight % CaC03)
where the WVI R is m g/m~t24 ho~ ma~d at 37.8~ C, 90% RX While ~ film
~o mcludilg a m-polye~ylene and fill~ foU~ws t~o gellaal o~
WVTP~ = -9967 + 3S8 (we~t % CaCo3)
The relationship ~s at const~t draw (onentation TD3 of 2.7:1, 3ine spee~ 103.6
metu,, pe~ 11te (mpm) (340 feet) per mmute (f~m).
BRIEF l)ESCRII~I ION OiF l~E DRAWINGS
~5 The fotegoin~ ects, feature~ ant advantages of the prese~t mven~on will
become cle~rel a~d more fi~ 3~ood w~ tho ~ ~ .~B d~silcd dcs~, ~tio4
and appended cl~ims are rea~ m co~nc~ e accomp~ying d~awiDgs, in
wbich:
F~gure I ilhwates the ~wdo~m ad~Dtage o~filled m po~ethyle~le over
ZN poh~ yleDe w~h ~ plot of =basis we~ m g/m2 ~er.su~ fill~r loadi
~1ENDED S~
CA 02262364 1999-01-26
WO g8/0SS01 1~ 7n357
- 4 -
Figure 2 illustrates the WVI~ advantage of m-polyethylene versus Z-N
pol~ll"~ e in a plot of WVTR versus ~e..,~ Lage of filler CaC03 both at 2.7:1
draw ratio and 22 g/m2 basis weight.
D13:TAILED DESCRIPTION
Introduction
This invention concerns certain polyethylene/filler films that will have high
WVTR and the ability to be drawn down to low basis wei~hl~ and methods for
making same. Particularly useful in these films and methotlc will be m-
polyethylenes.
In certain embodiments of the present invention films of m-polyethylene
and filler can be made with lower amounts of filler and still attain substAntiAlly the
same WVTR as previously known and used Z-N polyethylene/filler combinations
(at higher filler loA~fi~) are also conte~..rl-~e-~ This invention further incl.ldec
certain m-polyethylenes, their conversion into fabricated articles such as films,
articles made from such films, and applications in which such articles having high
WVTR combined with good physical properties are desirable. The reslllting films,and film composites, (inçl~l(ling coextruded and lA.I~ ed films) have colllbinalions
of propellies rendering them superior and unique to films or film composites
previously available. The filled m-polyethylene films disclosed herein are
particularly well suited for use in producing certain classes of high WVTR films,
con~mer and industrial articles using the films in co.llb;nalion with for inst~nce~
polymeric woven or non-woven materials. Such consumer artides inr,l~ldç, but arenot limited to diapers, adult incontinence devices, fP.minirle hygiene articles,medical and surgical gowns, medical drapes, industrial apparel, building products
such as "house-wrap", roofing components, and the like made using one or more
of the films disclosed herein. Additionally the films having increased WVTR of
the present invention may also be used in met~lli7ed films with a high WVTR
according to the disclosure of U.S. Patent 5,055,338, fully h~col~ol~led herein for
purposes of U.S. Patent practice.
In an embodiment of our invention, the filled m-polyethylene films, when
~riented after film formation, would surprisingly and unexpectedly have high
~ . . . .
CA 02262364 1999-01-26
WOg8/OSSOl Pcr/uss7ll3s7s
S
WVTR when c~ ed to a filled polyethylene film made using previously
available Z-N catalyzed polyethylenes. Following is a det~iled desc.i~,lion of
certain pl~r~,.ed m-polyethylenes, films, or film composites made using these m-polyethylenes and articles made from the films or film c~...po,~;lr~, that are within
S the scope of the present invention. Those skilled in the art will ap~.~;ale that
numerous mo~lifir~tions to these pr~fe..~d embodiments can be made without
depa.li-.~, from the scope of the invention. For eY~mr'~, although films based on
low density m-polyethylenes filled with CaC03 are rYemrlified herein, the films
may be made using co~binalions of m-polyethylenes with other polyolefins and
with other fillers or filler combinations. To the extent my description is specific, it
is solely for the purpose of illustrating pleÇe,.ed embodim~nt~ of my invention and
should not be taken as limiting the present invention to these specific embodiments.
Production of the Films
Films contrmrl~ted by certain embodiments of the present invention may be
made ~ltili7ing m-polyethylenes, by processes inçlutling blown and cast, preferred
is a cast film process. In such extrusion processes, the films of the present
invention can be formed into a single layer film, or may be one layer or more of a
multi-layer film or film composite. Alternatively, the m-polyethylene films
described in this disclosure can be formed or utilized in the from a resin blendwhere the blend components can function to modify WVTR, physical properties,
draw-down sealing, cost, or other functions. Both blend components and functionsprovided thereby will be known to those of ordinary skill in the art. Films of the
present invention may also be included in l~min~ted structures. As long as a film,
multi layer film, or l~min~ted structure includes one or more m-polyethylene/filler
film layers having the WVTR, or draw-down, and the like of the film, and the
M~$" CDBI and the like of the m- polyethylene, in the ranges described herein,
t will be understood to be contemplated as an embodiment of the present
mventlon.
Polyolefin Component
CA 02262364 1999-01-26
~6~iO42.PCT
- 6 -
The poly~lef~ CQ~p ~ can be ~ny film formmg polyolef~ or po~olefin
blend, as l~ng 3S ~e major~y of tbe polyvlefill c~o~ is a poh~olefin w~th the
follow~ng r~ ~ e~,.
yLer~l~d more p~.. d most prefened
s MJM~, < 3 c2.S
CDBI >509'o ~60% >6S%
MJM, cz
General~ ese rallgs dictat~ the use of a metadocelle cataly~d polyolelin,
p,~f~ polyeth~lene, P~ ~b a l~ne~ bw densi~y m~polyethylene w~th a
den~ m the range of ,~om 0.90-0.M0, p~f~l~d 0 910~ 35, more preferred
O gi2-0.925 ~on3. ~ es referred to h~e~ u~ gcn~ be po~mer OI resm
d~n g~i~Sl ~e~ ~~nW~e ~lJ~ A
There is a wide vane~y of cw.~ ~d exp~ po~e~hyle~e
resms usefi~l m the n~n~icture of films me~ded i~l certain embo~nn~ts of the
presen~ m~ntioQ. A no~-inch~sive lis~ iq ~o~d ~dow alo~g w~h tSe ge~eral bu~k
re~n properties ~s ~ Pd
TABL~: A
C L~ De~it~7 L~lt I
~3~ ~It
Omi~)
Exox~910~ 0.917 I.O e~A~x~
~now3SOL65Or3S0DKO)~
Exox~301now3S7C30~ 0.913 3.4 ~one
ExoxdD37~D60~ 0.9~? 1.0
Exo ~ 109~ 0.92~ 075 ~h~x~ne
E~D3028~ 0.900 1.2 c~
E~ox~D3~C3~ 0.917 3.4
Exaxd~ 363C32 0.917 t.5
ECI~Ol Q.gl7 4.5
Exoxdg377DtU 0.922 1.0
Exceod ~D 399L~ 0. 92S . 75
3S ~l~e fiom ~ Cbemical Co. ~al, TX, USA
~Th~xox~g357C~2i~u~ ~sngn~b ~ ~ECI~112and~Cr~115uud ~ ~
It u~l be understood ~ in ge~leral we con~1ate that a large number ~f
m-p~lhyl~es will be use~l in the tecbniques and ~pplir~ nc deswi~ed herem
1n~ 1ed cu~ o ~c nts. ~ butel~ copolym~, ~Lb~ bex~e
copcl~mers, ~ e~ l-octe~le copolyml~rs, eth~lene-4m~yl-l-palt~e
CA 02262364 1999-01-26
~e~ ~ 0.\ ~ I IL~ )f i ~ 3 ' "'~ ; l o~ i3 ~ 1 0 ~ 3~ '~ 3')~ 7
~042.PCr
- 7 -
copolymers, ethylene dodece~e copo~ers, ethyle e-l-pente~e copoly~ne~ as
well as ethyleDe copolymersi of one or more C~ to C20 co~t~ming alpha-olefins,
diolefins, ~nd cu~&~ons thererv~ A q rlll4ive list of such polymers;
~yl~e, ~-~utene, 1-pentene; et~len4 1-butene, 1-hex~e; ethylesle, I-butene, 1-
octe~le; e~ylene, l-butene, decene; e~hylene, I-pa~~ne, 1 ~ex~ hy~
pente~, I-oct~e; ~hyl~e, l-pentene, dece~e; ethylene, l-octene; l-pertene;
ethylene l-octe~e, dece:le; eth~ene, ~ netbyl-l-p~~ e, l-~ute~le; ethylene
methyl-l-pentene, I-pe~e~e; ethylene, 1 msthyl-1-pent~e, l-~exe~e; edlyle~e ~
methyl-l pentene, l-octene; c~hylene, ~methyl-l-p~tPn~, dec~e. Tnc~lded in the
o ethylcne copol~rs will be o~e or more ofthe abo~e ~onol~is inchded at ~ t~tal
le~vel of 0.2 ~o 6 mol~ p~rce~L pl~,.bly 0.~ to 4 mole pe~cent, ~r such ~ole
percents c~s~ h the resm d~i~s eoQten~plated.
D~fin;t~nnc and methods of ~ nn of CDBI may be folmd in U.S.
5,008,204 ~iC~ ~ ~ ~CO~O-a~ed by r~f~cace h~em for plUpO~S o~ U.S.
patent prac~ice.
l~e resm and product properhes recited m this spe~fi~sti~n were
des~ed m ac~ordance wi~h the fonow~g test pTooedures. Whese any of these
prop~ .s is l~f~ .cc~ m the ~pp~ded claims, ~ LS to be m~9SUI-ed31L accor~ce
~th the ~;~d test procedure.
T~BLE: B
UDjU I . . C
~Itlntex ~nlin ASr~D- 23 ~)
~Cm3 AST~ S0'
~V~. ~/m2J24~ ' ~ ~c~
FILLE~
Fi~lers usefill in this ;nv~ nuy be any morganic or organic material
havm~ a low affinity ~or snd a ~.;1~ lower ~ than the po~rolefi~
2S component. P~ thc fi~ler should be d ng~d _:e -' ~g a llo~-smoolh
h~ h2~ ce, or a m~cri~l which is ~reated to renda its sur~ce
hyd~ ot ~ .,f~lcl me~m average particle s~zc of the filler is beswe~ 0.5-
rn ~uF~T --
CA 02262364 1999-01-26
9GB~42.PCT
- 7d -
5 llm for films generally having a thickness of between 25.4 - 152.4 ~m (1-6 mils)
prior to
AMENl)E~
CA 02262364 1999-01-26
WO 98/OSSOI Pcr/uss7/l3s7
- 8 -
;,llete~ g Examples of the inorgsnic fillers include calri~m c~l,ona~e, talc, clay,
kaolin, silica, diatornaceous earth, m~gne-.ln c&ll,onale, barium c~l,ol~le,
.~2 g o~s;um sulfate, barium sulfate, c~ m sulfate, ~ minnm hydroxide, zinc
oxide, ma~y~r~ . hydroxide, çg~ m oxide, m~8;~f~ oxide, titanium oxide,
S s~hlmin~ mica, glass p~wder, zeolite, silica clay, etc. C~ m ca~l~onale isparticularly pr~,rc,,ed for low cost, whitenç~c, i"~,.l.~ess, and availability. The
inorganic filler such as c~ carbonate are pl~relubly surface treated to be
l.~.llophobic so that the filler can repel water to reduce agglo",elulioll of the filler.
Also, the surface coating should improve binding of the filler to the polyrner while
allowing the fuller to be pulled away from the polyolefin under stress. A p~ t;rellcd
coating is c~lrium stearate which is FDA compliant and readily available. Organic
fillers such as wood powder, and other cellulose type powders may be used.
Polymer powders such as Teflon ~) powder and Kevlar ~ powder can also be used.
The amount of filler added to the polyethylene depçn~ls on the desired
properties of the film inr.ll~ing tear strength, water vapor tr~ncmiC~inn rate, and
stretchability. However, it is believed that a film with good WVTR generally
cannot be produced as is taught herein with an amount of filler less than 20 percent
by weight of the polyolefin/filler composition.
The minimllm amount of filler is needed to insure the interconnection within
the film of voids created at the situs of the filler particularly by the stretching
operation to be subsequçntly performed on the precursor film. Further, it,is
believed that useful films could not be made with an amount of the filler excess of
70 percent by weight of the polyolefin/filler composition. Higher amounts of filler
may cause ~liffic~-lty in compounding and significant losses in ~llellglh of the final
breathable film.
While a broad range of fillers has been described at a broad range of
inclusion parameters based on weight perce"lages, other embodiments are
contemplated. For in~t~nce, fillers with much higher or much lower specific
gravities may be included in the polyolefin at amounts outside the weight rangesdisclosed, they will be understood to be contemplated as embotlimçnt.c of our
CA 02262364 1999-01-26
9GBo42.PCT
- 5 -
invention as lon~ as the final film, after orientation has WVTR or drawn down
similar to tllat described herein
STRETCHrNG OR ORIENTrNG AND HEAT SETTING
Final preparation of a breathable film is achieved by stretching the filled m-
polyethylene precursor film to form interconnected voids. Stretching or
"Orientation" of the fihn may be carried out monoaxially in the machine direction
(MD) or the transverse direction(TD) or in both directions(biaxially) either
simultaneously or se~uentially using conventional equipment and processes
following cooling of the precursor film
Film orientation may also be carried out in a tentering device with or
without MD orientation to impart TD orientation to the film. The film is grippedby the edges for processing through the tentering device.
Stretching of melt embossed precursor films with a tentering device at a
film speed of 60 97 - 152 4 meters (200-500 feet) per minute produces bre;lthable
films having the desired water vapor permeability. The resulting films had a greater
permeability in the areas of reduced thickness in comparison to the areas of greater
thickness.
A range of stretching ratios from 2:1 to 5:1 prove satisfactory for MD
stretching with a ratio of 4:1 being preferred. ~ range of stretching ratios of 2:1 to
5: I prove satisfactory for TD stretching with a ratio of 3 :1 being preferred.
It is preferred that tension be maintained on the film during the heat setting
and cooling to minimize shrinkbacl~. Upon cooling to ambient temperature (i.e.,
room temperature) or near ambient, the holding force may be released. The film
may contract somewhat (snapback) in the TD but will retain a substantial portionof its stretched dimension.
Heat setting can be accomplished by maintaining the film under tension in
the stretched condition at the heat setting temperature for 1-2 minutes. Preferably,
however, the heat setting and cooling is carried out while permitting the film to
contract slightly, but still under stress. The controlled shrinkback of from 5 to
AMENDED SHEET
. .
CA 02262364 1999-01-26
9CB042.PCT
- 9d - .
30%, preferably between 15 and 25%, of the maximum stretched width has given
particularly good results in eliminating storage shrinkage.
NDED SHEEr
... ~ . . , .. . ~ ....
CA 02262364 1999-01-26
W0 98/OSSOl l ~ 7ll3s78
- 10 - -
1 . c .,~. lia of films Droduced ~rom the resins
WVTR
In an embo~ n~,~t of the present invention, certain films and articles made
ll~r~ .l have higher WVTR than previously th~ght possible. The WVTR of
S such films should be above 100 glm2/day ~ 37.8~ C, 90% RH, p~f~dbly above1000, more pi~;rhu~ly above 3000 glm2/day (~ 25~ C. This can be seen in Figure 2which il1ustrates the WVTR advantage of m-polyethylene versus Z-N polyethylene
in a plot of WVTR versus p~,.c~nlagc of filler CaC03.
In general the films of embodi~ of the present invention will have a
much higher WVTR at the same filler loading than previously known Z-N
polyethylene based filled films. Specifically, the inventive films will have a WVTR
at least 10% higher than the WVTR of the co."palali~re films described by the
equation: WVTR= -10,900 + 320 (weight % CaC03)
In another embodiment of our invention a m-polyethylene/filler conlbinalion
film can be stretched (oriented or tentered in the TD) less than a Z-N polyethylene
col"bir.alion film, and still achieve s.lbs~ lly the same WVTR (at generally thesame filler loadings). This is a signifil~.~n~ advantage to a film maker because the
greater the orientation, the greater the chance for a film imperfection to be
magnified, potentially causing a catastrophic failure (break).
It is not beyond the scope of embodiments of my invention to blend the m-
polyolefins to form the films of the invention with other materials such as other
linear polyethylenes (HDPE, MDPE, LLDPE), low density polyethylene (LDPE),
polyl"o~ylene (PP) (homopolymers and copolymers), polybutene-l (PB), ethylene
vinyl acetate (EVA), or other ethylene polar comonomer copolymers and the like
to fabricate useful articles. Such potential blend polyolefins may be conventional
Zeigler-Natta catalyzed, chromium catalyzed, free radical initi~ted and the like.
However, the WVTR of the layer or layers int~nded to impart WVTR should
generally be within limits disclosed above. Additionally, any blend component orcomponents additive or additives should be chosen such that the desired WVTR of
the film remains at or above the targeted or desired value. Any blend should
preferably contain a majority of m-polyethylene as the polyolefin component,
.. ...
CA 02262364 1999-01-26
9Gr~042.PCT
specifically greater than 50 wei~ht percent, preferably greater than 60 weight
percent, more preferably greater than 70 (75?) percent, based on the total weight
of the polyolefin
Definitions and Test Protocols
V;llue Units Definition orTest
Density g/cm~ ASTMD-792
CDBI % *Definitionstest determination
contained in this application
Molecular weight distribution none
s
TEST METHODS
Water Vapor Transmissioll Rate
The WVTR test measures the quantity of water vapor that is able to pass
through a film. A Mocon Permatran W-l unit is used to measure WVTR by
passing a stream of dry air across the surfaces of the film. The dry air picks up
moisture that has passed, from wet pads underneath the film, through to the top
surface.
The moisture level is measured by an infrared (IR) detector and converted
to a voltage which can be measured on a chart recorder. The procedure also
1 5 includes:
a) Punching out a die cut hole in an aluminum foil mask,
b) Cutting offtwo opposing corners ofthe mask,
c) Peeling paper backing off of mask,
d) Cutting 5.08 x 5.08 cm (2" x 2")squares of film and place them over
the hole in the mask,
e) Putting the paper backing back on the foil mask, then
f) Placing the masked sample in the test cell with the aluminum side
up.
The chart recorder reading is multiplied by 100 to give the WVTR value.
Gurley Porosity
Teleyn Gurley Model 4190 Porosity Tester with sensitivity attachment is
used. With the procedure as follows:
lr ~ F~ S~iE-~.
CA 02262364 1999-01-26
9GBo42.1'CT
. .
- 12 -
a) Cutting a strip of film (~5.08 cm ("2") wide) across the entire web
width,
b) Inserting a film sample to be tested between orifice plates,
c) Setting the sensitivity adjustment on "5",
d) Turning the inner cylinder so that the timer eye is vertically centered
below the 10 cm~ silver step on the cylinder,
e) Resetting the timer to zero,
f) Pulling the spring clear of the top flange and releasing the cylinder,
When the timer stops counting, the test is completed. The number of counts is
multiplied by 10 and the resulting number is "Gurley seconds per 100 cm"'.
It will be appreciated by those of ordinary skill in the art that the films of m-
poiyethylene resins of certain embodiments of the present invention, can be
combined with other materials, depending on the intended function of the resulting
film.
Other methods of improving and/or controlling WVTR properties of the
film or container may be used in addition to the methods described herein without
departing from the intended scope of my invention. For example, mechanical
treatment such as micro pores.
DRAWDOWN
Embodiments of the present invention offer a significant and unexpected
improvement in the ability for the formulations to be drawn down. Specifically,
using conventional Z-N polyethylenes, a lower limit of 63.5 (2.5), more practically
&8.9 ~m (3.5 mils) has routinely been observed (as extruded) upstream, i.e. before
orientation. By contrast, films of embodiments of the present invention, may be
drawn down to a practical limit of 50.8 ~m (2 mils), providing a significant
advantage in terms of either economics or a combination of economics and
softness. The softness comes due to the decreased modulus of the lower thickness.
Ultimate drawdown is defined as minimum gage (or basis weight) before the onset
of draw resonance at a given extruder rate (e.g., kg/hr. (Ib./hr)).
The films of embodiments of the present invention will have ultimate
drawdown more than 20%, preferably 25%, more preferably 30% less than that of
AMFl\lDEI) SHFFT
CA 02262364 1999-01-26
9GB042.PCT
- n -
filled Z-N polyethylene which~ from Figure 2 has an ultimate drawdown described
by the general formula: W = 2.1 + 0.380 (weight % CaCO3)
EXAMPLES
All polyethylene/filler materials were stabilized to diminish the effects of
extrusion.
Orientation of all the following examples was performed at a 2.7: 1 draw
ratio, at 10.7 meters per minute (35 fpm), 65 - 104~ C (150-220~ F) tenter
temperature, ~2 - 110~ C (180-230~ F) annealing temperature.
Example 1 - 3
Examples 1 - 3 were fabricated from EscoreneTM LL 3003.09 on a 15.25
cm (6 inch) Marshall & Williams cast extrusion line at normal processing
conditions processing conditions listed in Table la.
Example 1 used a 50/50 weight ratio of the polyethylene to CaCO3, while
examples 2-3 used a 65/35 ratio of polyethylene to filler all films were subsequently
oriented (TD) to three different basis weights as seen in Table 1.
Examples 4-9
Examples 4-9 were fabricated from ExceedTM ECD-112, under th~ same
processing conditions as examples 1-3. Examples 4-6 used a 50/50 weight ratio ofthe polyethylene to CaCO3, while examples 7-9 used a 65/35 ratio of polyethyleneto filler. All films were subsequently oriented (TD) to three different basis weights
as seen in Table 2.
From the data in Table 1 for each of these examples run, it can be seen that
in Example 1 and 2; as filler level goes down, WVTR goes down dramatically, and
as seen from example 3 a lower basis weight only marginally increases the WVTR
of the film with a higher percentage of polyethylene. By contrast, from table 2 for
examples 4-9, a much higher WVTR is achieved by the same filler loading and
basis weight, than for the films of examples 1-3, moreover, while a higher
percentage of polyethylene in the formulation (examples 4-6 vs. 7-9) generates adiminution of WVTR, the percentage is far lower than that experienced for the Z-N
polyethylene of examples 1-3 (95% reduction vs. 68% reduction)
al~AF~nFn ~HFET
CA 02262364 1999-01-26
s6uo42.rc-r
14 -
Examples 10- 15
Examples 10-15 are run as in Example 4-9, but the polyolefin component
was a blend of LD-20~ -MI, 0.917 g/cc low density polyethylene available from
Exxon Chemical Co.) and ECDI 12. As can be seen from the data in Table 3, at
the same basis weight Examples 4-6, and 7-9, the corresponding films of Examples10-15 had somewhat lower, but still acceptable WVTR. Also of note is Example
15 which was the lowest basis weight attainable in this series (1-15) of examples
(again orientation was TD).
Examples ]6-23
Examples 16-23 were extruded similar conditions to the previous examples,
into two (2) thickness of precursor (before orientation) film 114.3 and 152.4 ~m(4.5 and 6 mils) and oriented in the MD at 79.44~ C (175~ F). While WVTR
results for this set of examples appear to be substantially the same for both
metallocene and Z-N polyethylenes, it is anticipated that when the orientation
speed is increased, the m-LLDPE will show improved WVTR, over the Z-N-
LLDPE, just as found in the TD orientation in examples 1-15. The results are
shown in Tables 4 and 5.
Examples 24-25
Examples 24 and 25 were extruded under substantially the same conditions
as the previous examples. Examples 24 is substantially the same in
polyethylene/filler content as example 4 and example 24 is substantially thc same
mal~e-up as example 1.
Example 24 was drawn (oriented) at a 2.7:1 draw ratio, while example 25
was drawn at a 3.8:1 ratio. These examples show that the m-LLDPE at a lower
(28%) draw ratio than the Z-N LLDPE, example 24 has generally the same
WVTR. The results are shown in Table 6.
While the present invention has been described and illustrated by reference
to particular embodiments thereof, it will be appreciated by those of ordinary skill
in the art that the invention lends itself to variations not necessarily illustrated
herein. For example, it is not beyond the scope of this invention to include
additives with the claimed films or to blend resins to form the claimed films with
!3~;;,' S~
.
CA 02262364 1999-01-26
9~B042.PCT
- ;5 -
non-wovens and the like. For this reason, then, reference should be made solely to
the appended claims for purposes of determining the true scope of the present
invention.
TABLE 1
ORIENTED FILM PROPERTIES
LL 3003,09 B;~sed S;lmples
XPROPERTIES Ex;lmple 1 l~x:lmple2 Example3
Basis Wt., g/m2 22.1 22.5 18.7
Yield, m /kg (vd /Ib.)9.84(24.6) 9.64(24.1) 11.6~29.0)
Emb. Cal., um(mils) 29.7(1.17) 28.7(1.13) 24.8(.98)
Gurley, seconds 1137 Off-Scale Off-Scale
WVTR, ~lm2124 5]00 300 500
MD Tear~ ~ 473 486 386
TD g 9 8.5 7.8
Opacity~ % 59.5 39.1 38.1
MD 10%, g/cm(g/in) 125.9(319.8) 164.5(417.9) 159.3(392.0)
MD 25%, g/cm(~/in) 138.6(352.1) 169.1(429.6) 163.0(414.1)
MD Ult., g/cm(g/in) 179.6(456.2) 194.6(494.4) 193.8(492.3)
MD Elg., % 343.8 340.8 358.6
TD10%,g/cm(=g/in) 270.8(688.0) 354.4(9004) 680.31(728.0)
TD 25%, ~/cm(g/in) 429.9(1092) 547.6(1391) 446.4(1134)
TD Ult., g/cm(g/in) 679.1(1725) 797.2(2025) 725.2(1842)
TD Elg., % 127.1 131.6 136.5
DR Limit g/m2 21.1 15.4 --
~ The "DR Limit" also know ~s Ultimate Dr~wdo~n" is the basis weight at which we
first observcd draw reson;ll1ce. The DR probe was conducted with the mpm (fpm)
fi.~ied at 103.63 (340) and the e~;truder RPM reduced gradually until the onset of draw
resonancc.
~MEI~IDEO SHFFT
CA 02262364 1999-01-26
9GB042.PCT
.
- 16 ~;
TABLEl~
E:~tru~ion Conditions
(for 22 ~/m2 s:lml)lcs)
CONDITION E~,lml-lc I E~ millc2E~lm-llc4 E~ ml)lc7Ex:-mi~lc 10Example 14
E.~;t. Rl'M 23.0 26.4 19 1 21.6 29.5 31
Upslrcam, i;Pa 23.q9(348()) 25.78(3740)25.71(3730)31.919(463l)) 30.590(4430)
; 10 (psi)
Do~n,i;l'a ').31(131()) - 8.75(1270) 1160 7.997(1630) 10.272~1490)
:;lO'(pSi)
MeltTc~np.,~C 2194(i27)221.4(436)221.1(430)221.67(431)236.6(458) 232.78(451)
( i )
Up Width, cm 9.2(23 4)').17(23 3)8.58(21.8)8.58(21.8)12.24(31.1) 11.96(30.4)
(ill)
Do~n Width, - 23.97(60.9)24.64(62.6)24.44(62.1)34.0(86.4)
cn~
CastRo11, 96.92(31X)1o3.93(34l) 103.63(340)103.63(340)103.32t339) 103.63(340)
"~I",.(r~"..)
dra\~ ratio for ~11 e:;amples t~rgeted at 2.7-1, (ratio of outlet width divided by inlet width)
TABLE 2
ORIENTED FILM PROPERTIES
1 0 Fol- ExcccliirM ECD-112 B;~cd S;lml)lcs
PROPERTIESE~;lml)lc IEx;nnl-lc 5E~;ami~lc GExaml)lc 7Examl)lc 8 EYsmple 9
B~ t ~/m~ 22 ~/m IX.5 ~/m 1~ g/m 22 ~/m 18.5 g/m 15 g/m2
(T:lr~ct)
Basi~ Wt.~ (~/m 22.7 1 ~.6 I j.2 22.8 19.2 14.8
Yic1d, In~/~9. j6(~3 9)11.68(29.2)14.38(3j.7)9.j2(23.8)17.32(28.3)14.68(36.7)
(~i /lb.)
Elnb. Cal.,.1.2(1 23) 24.3(.96) 20.j(.81) 31.4(1.24)26.1(1.03) 19.5(.77)
ils)
G~ule!.scconds 2i6 159 127 3608 2 40 1095
WVTR, ~Im'12479 jn 83;() 8 i: 0 2575 3~75 4J1
MDTcar, ~ ~0() 360 33) 418 405 '9
T D .() 7.2 7._ 7.2 7.0 ~.
Oilacil~,~/u (6.2 62.3 59.1 51.6 48.3 44. ~
MD10'~"g/cm117.')(299.6)87.2(221.~)) 7j.~(191.9)171.0(434.4)14j.4(369.6) 113.4(2 8.1)
(Jill)
MD 25%. 150 9(3i~3 3)97.2(247.1)83.8(213.0)171.2(43j.0)144.9(368.2)112.3(285.3)
~/cm(Jill)
Ull., I')j.()(496.9)1~7.4(32~.6)116.7(296.j)197.4(501.6) 162.1(411.9) 118.9(304.7)
o/cm(o/ill)
MD El~., ~~, 327.5 290.0 331.2 293.1 276.4 271.4
TD 10%, 290.2(737.3)245.j(623.6)202.2(jl3.7)367.2(932.9)329.2(836.4) 267.1(678.6)
~/C111(~/ill)
TD25%, 46j.3(1182) 394.8(1003)33j.3(851.8)591.7(1503)528.3(1342)437.4(1111)
Jclll(Jil~)
TDUlt., 890.1(2261) 733.4(1863)619.6(1574)1158(2942)1058.6(2689)864.9(2197)
/cl ( ~/i ll )
~) lr ~/~ 110.2 100.7 95.5 103.5 103.3 97.1
D . _ mit Jm'13.4 _ _ 10 3
~ The ''DR Limit'' is the basis wei~ht at wllich we first observed draw reson~n~e The
DR probe was conducted witll the mpm (fpm) fi~;ed at 103.63 (340) and the extruder
RPM reduced ~radually until thc onset of draw rcsonance.
~iENDED SHEE7
CA 02262364 1999-01-26
9C~04~PCI'
- 17 -
T.~BLE 3
ORIICNTll~D FILM PROiPERTllCS
For saD~ile~i ba~ied ao ~c~d~ 1CD-112 blrnded ith LD P~ (LD-202)
~~~n~5 ~u~pbl~ E~unp~ ku~pkl2 ~umpb13 ~uu~e14 ~LU~e
3~.5# ~i 37~% ~i 37~-h E~ ~3Y ir0 56 3~~ ~0 563%
l~Y iLD~ LD 125% LDi ~r~ LD a7-~o LDi a7% LD
C~ ~i% C~c ~i% C~c 3'i-,'.C~ ~% C~c 3S% C~c
22 ~ Jz i~ ~S ~m~ ~ zl~,2 1~.0 di~' 12 ~in~
B~is W~ mZ 22.1 17.9 14.7 22.9 13.9 12.1
~d m2~ 9g4(24.6)12.12(30.3)14.76(3C.~)9.48(23.?)15.6(39.0~17.92~.8)
(ydl/lb.)
Emh C~l. 27.4~1.08) 2S.}(.99)l8.5(73) 28~19(1.11) 17.78(70)15.(.62)
Gt~rlev, S~COlld5f 1:~5 a 4 398 l ,-n 69:~ 71~
WV~ ~mln4 4 flO 5 _~ 5925 1~ .3
h~DT~r.8 u ~ 85 I ~
Opaaty ~ 59.7 SS.6 5.. 2 5--.6 40.3 3 .7?~) ]~2.2(361.3)119.9(30~.6) 100.61~25S.~) 186.1~47~) 130.41331.2) 10~(277
10Y4&~cn~1g~ut)
MD 2~Y. 154.1(391.6)130.6(;31.9) 110.9(2ai.~) 207.3(526.7) 128.8(32~ 0.3~280r2)
~DU~. 6~.2~441.1)1~4.7(~77) 12;L61~311.4~ 207.3~S26.T~ 138.8(3S2.5) 116.7(296.5j
~/cm(~'in)
163.2 137.3 103.2 2~9.8 202.8 177.2
252.2(~1.~)204.~(S20.5) 171.~(435-5) 32~(82~- ) 20~4(560) IBI.2(460.5)
Bl~in) ,,
lD 25~o 38~.7(985);17.4(806.4) 261~678.2) 5n9.4(1294j 349.7(888~4) 288.7('334)
g~cm(~lo'
ll~UI~ g/n 621.2(1578)514.5(1307~ 471.2(1197! 1011.~:5~9~ 752.7~1912~ 554.3~1~)
TDEI~.~~ 97.8 96.6 10~.2 111) 113.2 103.3
!~R L~mit~ 11.5 -- -- <b.~
~ The "DR 1~" i~ ~s we~g~ at ~ h we fi~ obs~l ~aw 1~ r)~ C~ T~e
DR p~e wa~ ~ J~ ~1 ~n~h the ~pm (~m~ fLxed at 103. 63 ~;40) a&d tn~ ex~
R~M ra~uced grad~lally ua~ ~~e ~s~ of ~raw
i~?i!c:~iG~r~
.. . . .. .. ...
CA 02262364 1999-01-26
K~S~So~ ~ ~r 1:1-10-~3~ ~.3 ~ 3 7101~ +~3 ~ t :1
96~0 ~''.PCI'
TABLE 4
79.49~ C (17S~ F) Orie~ oll
114.3 ~m (4~ mil) precursor film
PR~PERTY ~samplo 16~ ample 17 }~ample lo: ~xample 19
50~ C~CO3 SO% CaC~, SO% CaCO, ~ ~ 50'Y~ CaC03
inECI~ ~ ECr~115 jn.lT.~3n~09 ~LL300309
S:l ~vR;~io C~ w~io ~ atio ':1 ~TawRa~o
BasiisWeight~/~ 54.~ ~.S ~. 4i ~ -7
iiCaliper,,um~mils) 61. (2.43) -~(1.93) ':.~(3.29) ~ ''79
~,glm2124hours t'100 "l O ~ O
GurtqP~Irouty, soc ~55 0~ : 8 : o
MD Te~ile at 5Y., 30.~ 4) . 0-.4(1289) -~t .7(1084) :; ".lil3~4j
~DTeasileatl09~. 901.6(2290) 1194.4(3034) 862.9(21g2) 1197.2(3041)
~W~n)
~T ~cat2S~'a. 1781.~4540) - 1~85.~3174)
g/c~
~UDrenuleatB~aL 2863.~7~3) 3041.3(77~.~) 2001 ~5085) 2415.~a3S)
~cm~y~
hlI)Elon~ AtBr#lL~ 73.~8 19.65 78.74 20.78
TDTen~ t5~/o, 79~l(2ol~l) 40.3(102.4) ~0.3(17~.n 41.3~104.~)
~crm(~Jin)
TD Te~sikatl0%, 1;1.2~333.~) 77.3~l96.5) 115.5(293.4~ 72.t(184.7
~Icm(L'i~)
TDTe&siLeat25%, 170.g(4~2.9) 12S.0(317.6) 148.0(37S.g) 103.8(2C3.9)
~'~in)
TDT~r~leatBreak, 223.8(568.6) 12 ~(318.1) 190.0(~a~8) 109.0~276.9)
~cm~
11~ on~ AtB~ ,~ 350.1 2~.7 315.7 2"8.S
f Toar, p~ns ~ 0 2 1 .2
~n)Shrinlcat~6.6~C(~10~ 13.5 17.6 lO.S ~.0
F) %
TDSh~Dk~t76.6~C(170~ ~30 -3.] -3.8 -~9
~) 'Yo
Note: ~11 samples~nP~ d w~Ih a ~.~7 mpm ( 15 ~m3 i~ speed, 8~.78~ C ( ] 90~
F) r-n~ d ~a"o r~
A~JIEMOE~ S'r~
. ~ . .
CA 02262364 1999-01-26
r ~a~ "~ r
96EC42.PCT
- 19
TA~
79.44~ C (17S~i ~ Orierit~io4
l S2.4 ~ m (6-0 ~iF~ ~ G ~ fil~i
RTY ~pl~0 : : ~ample 2I E~xample 22 E!xaalple 23
50~ O~6Caco3 ~0~A~CaC03 SO~Y Ca~
- ~E~I~5 ~ ECr~ iriLL3003.09 ~ ~,3003.09
- 4:1 ~Ratia. 6.1 ~rawRatio ~ l ~;rwR~o 6:1 ~raw R~
: as~ Wei~t, yD~ .72 4~.47
~ -- ~ Caliper. ~mil~) ~. . (3.30~ .28(3. ~o) l~i.2(2.55)
~VTR 0'm-~24 hou~ ~ o ~io ~ 2~0 ~uo
.~DDTe ~ e~,Y~ 1336) ~711~g~) 3~.3(1370) 6~ 39)
~B/~n)
~DTe~e~10~ 233?) 1453 1(3691) 108S.~758) 1151.~3686
~cn~in)
MD Tenule al 25%, 2203.3~5S9~ -- 186~.3(~736) lg78.3~5~25
g/cn~'g/i~)
~DDTen~le~ 8n~ 3659.~9_q4i 3911.~ ~34) 2413.7l6131) 29~.j~7179j
~DD ~o~ AtBxa~ % 78.35 2t.08 75.36 ,4 01
TDTen~le~%, 11~303.9) 47 7(121.;) 95.2(241.8~ 56.7~ 2
~/cm(~in)
TDTo~eatlo~, 186.~473.4~ 93.7~238.2) 149.2~3~9.2) 96.7~45.6)
~cm(~in)
TDTo~at 5%, ~2.~589.7) 16S.~421.~ 186.5(4~3.8) 128.7i326.9)
s/cm(~in)
TD Ten~eat3na~ 323.1(820.8~ 182.X464.8) 249.~634.7) 14~.3~356.5)
~/~(81i~)
TD Flcns.~t~a~ ~ 3~8.0 ;30.' ; 6.8 2~0.3
~D~ TOEu,g~ns 0 ~ ~, 2 13.2
DSh~n~76.6~C~170~ 13 .~ .5 14 9
~%
TDShn~ at76.6~C(1?~ -3 -3 -3 -2.S
E') %
~'ote: A~l sa~les l~n~sed wi~h a 4.57 mpm (1~ f~m) inlet 3peed, ~7.78~ C (190~
F) a~nealilg and S% r~
A.IJIENDE2 SHEET
.. . .
CA 02262364 1999-01-26
~GBW2.PCT . . , ~ ~.
TABLE 6
E.~aml)lc 2~ E~aml~le 25
PROPERTY MLLDPE Z~T LLDPE
50% CaCO~ 50% CaCO~
2.7:1 draw r;ltio ~.8 . draw ratio
Yield m~/kg (!d-/lb) 9.44(23.62) 0.. .9(26.23)
Basis Weigl~t glm~ 2~.13 :0.
Elnbossed Caliper ~m(lllils) 3 0(1.26) 0.~9(1.61)
Gurle\ Porosi~ Seconds/100cc 2-1 230
WVTR g/m~/21 hour 7613 7688
MD Tensile at 5 ~u Elg. Glcm(Grams/ n) 76.9(195.5) 68.7~1~4.7)
MD Tensile at In~O Elg. G/cm(Grams/ n) 105.9(269.1) 107.4(272.9
MD Tensile at 25~ Elg. G/cm(Grallls/ n) 118.7(301.7) 126.1(321.8)
MD ~ensile al Break G/cln(Grams/in) 188.0(477.6) 69.9(431.7)
MD :lol- . at reak U~ 346.1 :93.7
TD '''CllS e at ~ E g. G/cm(grams/ n) 1~6.2(371.5) :.. 7.8(5 3.3)
TD ~ens e at 0 /O: g. G/cm(grams/ n) 241.8(622.0) ~ 5.9(9 0.4)
TD Tens e at 25 /u E g. G/cm(grams/ n) 3G7.2(932.9) 6 0.0(1 02)
TDTensilealBreak G/cm(grallls/n) 619.6(1650) 851.1(2162)
TD Elol)~. a~ Break ~u 116.5 86.4
TD Sllrinkl~e a~ 7G.G~ C ~ 1.2 4.0
(17()~F)
