Note: Descriptions are shown in the official language in which they were submitted.
POLYMERIC POLYBLEND COMPOSITION
...
. `~ ' '.
The present invention relates generally to a
polyblend of at least two polymers. More particularly,
the present invention relates to a processable polyblend ;
of a vinylidene chloride interpolymer and a graft
copolymer.
Vinylidene chloride polymers are well-known
for their excellent barrier to mass transport of atmos-
pheric gases and moisture vapor, as well as good solventresistance. These interpolymers have limited areas of
application, however, because of poor melt processing
characteristics. In particular, vinylidene chloride
interpolymers in a melt plasticized state have poor heat
stability and low melt strength. These same
` interpolymers, when fabricated, tend to be brittle and
to have low impact strength.
Similarly, olefin polymers are well-known Por
their excellent physical properties. Specifically,
olefin polymers are easy to mold, inexpensive and have
excellent impact toughness. Olefin polymers provide a
relatively low degree of barrier to mass transport of
36,368-F
:'
2~
atmospheric gases and water vapor when compared to
vinylidene chloride interpolymers.
. . ~
In the past, the problems associated with the
poor melt processing characteristics and impact strength
of vinylidene chloride interpolymers has been partly ~ ;
avoided by blending said vinylidene chloride ;~
interpolymers with other polymeric resins (e.g., poly~
olefins). The other polymeric resins possess better ~;
melt processing characteristics and impact strength than
the vinylidene chloride interpolymers.
:,. ;:,
Unfortunately, a blend of the two resins is -;~
friable due to the lack of adhesion between the respec~
tive interfaces. The process of forming physical blends
of vinylidene chloride interpolymers with other
polymeric resins has proven unsatisfactory in that such `~
blends generally require the presence of a compatibil- ~ -
izing agent. While such polyblends represent one
20 possible solution to the poor melt processing char- ~-
acteristics and impact strength of vinylidene chloride
interpolymers, it is desirable to avoid the problems
associated with the use of vinylidene chloride inter- `~
polymers without necessitating the use of compatibil-
izing polymers.
It is desirable to produce a polymeric poly-
blend possessing the desirable properties of both a
vinylidene chloride interpolymer and an olefin polymer,
without having to employ a compatibilizer. It is to
this goal that the present invention is directed.
The present invention is a polymeric polyblend
comprising~
36,368-F -2-
(A) a vinylidene chloride interpolymer formed ~`
from an ir~terpolymer mixture which comprises a
- vinylidene chloride monomer in an amount of from 60
to 99 weight percent and at least one ethylenically
unsaturated comonomer copolymerizable with the ~
vinylidene chloride monomer in an amount of from 40 ~ -
to 1 weight percent, said weight percents being
based on the total weight of interpolymer monomer
mixture; and
~B) from 3 to 60 weight percent, based on the
weight of the polyblend, of a graft copolymer formed
from a polymerizable mixture comprising: (1) from
95 to 15 weight percent of a comonomer mixture, and
(2) from 5 to 85 weight percent of a preformed
polymer which is capable of imbibing the comonomer
mixture and of having the comonomer mixture graft
thereto, said weight percents being based upon the ~ ;
total polymerizable mixture weight;
whereby upon polymerization, the graft copolymer has at
least 5 weight percent of the comonomer mixture grafted
thereto.
The present invention concerns a polymeric -~
polyblend. Applicant has discovered that the problems
associated with vinylidene chloride interpolymers can be ,~
overcome by blending said vinylidene chloride
interpolymers with a graft copolymer formed by
polymerizing a monomer mixture comprising a vinylidene
chloride monomer and another ethylenically unsaturated
comonomer in the presence of a preformed polymer. The
polymeric polyblend has better melt processing char~
36,368-F -3-
,;,.",: ., . . `,,, .~ ,, . ' ' ' '. ' . , ';'. ' ;' '`;'
-4-
acteristics and better impact strength than vinylidene
chloride interpolymers alone.
, ~ .
For the purposes of this invention, it is
understood that the term "vinylidene chloride inter-
polymer" encompasses both homopolymers, copolymers9 ~ -~
terpolymers, etc. of vinylidene chloride. The
vinylidene chloride monomer may be copolymerized with at
least one monoethylenically unsaturated monomer.
'~
In preparing the monomer mixture, such mixture ~
contains essentially all of the monomer to be polymer- -~ -
ized. Vinylidene chloride monomer is present in an
amount of at least about 60 weight percent, based on
15 total weight of the monomer mixture. The preferred -~
ranges, as is known to the skilled artisan, are
dependent upon the presence and type of ethylenically
unsaturated comonomer copolymerized therewith.
Generally, the ethylenically unsaturated comonomer will ` -~
be present in an amount of between about 40 weight
percent and 1 weight percent, based on total weight of `
the monomer mixture.
` :, `'.~`~
The amount of ethylenically unsaturated
comonomer is maintained below an amount effective to ~
destroy the semicrystalline character of the interpoly- `
mer. By "semicrystalline charaoter" it is meant that
the interpolymer has between 5 percent and 95 percent
crystallinity. Crystallinity values depend upon the
measuring technique, and as used herein crystallinity is
defined by the commonly used density method. See, for
example, the discussion by R. A. Wessling, in Chapter 6 ,
of Polyvinylidene Chloride, Vol. 5, Gordon and Breach
`~ '
36,368-F _4~
,,-,......
: ., :. '::
,.' ~::~,.. .
: -5-
Science Publishers, New York, 1977, the teachings of
which are incorporated herein by reference.
Suitable ethylenically unsaturated comonomers
copolymerizable with the vinylidene chloride monomer
include vinyl chloride, alkyl acrylates, alkyl meth-
acrylates, acrylic acid, methacrylic acid, itaconic
acid, acrylonitrile and methacrylonitrile. The alkyl
acrylates and alkyl methacrylates are generally selected
to have from 1 to 8 carbon atoms per alkyl group.
Preferably, alkyl acrylates and alkyl methacrylates are
selected to have from 1 to 4 carbon atoms per alkyl
group. The alkyl acrylates and alkyl methacrylates are
most preferably selected from the group consisting of
vinyl chloride, methyl acrylate, ethyl acrylate and
methylmethacrylate.
When the ethylenically unsaturated comonomer
employed is vinyl chloride, the vinyl chloride is pref- ;
20 erably present in an amount of from 30 to 5 percent by -
weight Qf interpolymer and the amount of vinylidene
chloride is from 70 to 95 percent by weight of ~ ~`
interpolymer. ~ ;
`~
When the ethylenically unsaturated comonomer `
employed is an alkyl acrylate, the alkyl acrylate is
preferably present in an amount of from 15 to 2 percent
by weight of interpolymer and the amount of vinylidene
30 chloride is from 85 to 98 percent by weight of ~ -
interpolymer.
~:
Methods of forming the vinylidene chloride
interpolymers suitable for use in the present invention
are well-known in the prior art. The vinylidene chlo-
36,368-F -5-
~:
-6-
ride interpolymer is generally formed through an emul-
sion or suspension polymerization process. Exemplary of
such processes are U.S. Patents 2,558.728; 3.007,903;
3,642,743; and 3,879,359; and the methods described by
R. A. Wessling, in Pol~vinylidene Chloride, Gordon and ~-
Breach Science Publishers, New York, 1977, Chapter 3; -
all of which are incorporated herein by reference. ;
Typically, the monomeric materials are emulsified or
suspended in an aqueous phase. The aqueous phase
10 contains a polymerization initiator and a surface active ;-
agent capable of emulsifying or suspending the monomeric
materials in the aqueous phase. The polymerization of
the monomeric materials is usually carried out with
heating and agitation.
After polymerization is complete, the resulting ~-
suspension or emulsion of vinylidene chloride inter~
polymer has a majority of an aqueous phase. Thereafter,
the slurry is cooled down, fed to a dewatering process
to remove the water and dried.
To improve the impact resistance of the vinyl-
idene chloride interpolymer, it is blended with a graft -
copolymer. The vinylidene chloride interpolymer is
present in the polymeric polyblend in an amount ranging~;3~ ;
from a minimum weight percent of about 40, preferably
about 60, and most preferably about 70; and a maximum
weight percent of about 97, preferably about 92, and ` --
30 most preferably about 86, based on total weight of the -~
polymeric polyblend.
The graft copolymer is present in the polymeric
polyblend in an amount ranging from a minimum weight - ;~
percent of about 3, preferably about 8, and most
~ :.-:
" ~,. ....
36,368-F -6- ~
''~
preferably about 14; and a maximum weight percent of -
about 60, preferably about 40, and most preferably about
30, based on total weight of the polymeric polyblend.
The graft copolymer is prepared from a polym- --
erizable mixture comprising two components. The first
component is a monomer mixture, the second component is
a preformed polymer.
,:
The monomer mixture is present in an amount of
from 15 to 95 weight percent of the polymerizable
mixture and the preformed polymer is present in an
amount of from 85 to 5 weight percent, said weight
percents being based upon the total weight of the
polymerizable mixture. Preferably, the monomer mixture
is present in an amount of from 30 to 90 weight percent
of the polymerizable mixture and the preformed polymer
is present in an amount of from 70 to 10 weight percent,
said weight percents being based upon the total weight
of the polymerizable mixture. Most preferably, the
monomer mixture is present in an amount of from 60 to 75
weight percent of the polymerizable mixture and the
preformed polymer is present in an amount of from about
40 to 25 weight percent, said weight percents based upon
the total weight of the polymerizable mixture.
;
In preparing the monomer mixture, such mixture -`
comprises essentially all of the monomer to be polymer- ~ -
ilzed. The monomer mixture comprises vinylidene chloride
in an amount of from 60 to 99 weight percent, preferably
from 65 to 96 weight percent, and most preferably from
70 to 94 weight percent, based on the total monomer
mixture weight; and an ethylenically unsaturated
comonomer or monomers copolymerizable with the
36,368-F _7_
:
vinylidene chloride monomer in an amount of from 40 to l `
weight percent, preferably from 35 to 4 weight percent, `
- and most preferably from 30 to 6 weight percent. based ~- `
on the total monomer mixture weight.
Suitable ethylenically unsaturated comonomers ~ ;
copolymerizable with the vinylidene chloride monomer ` ~;
include vinyl chloride, alkyl acrylates, alkyl meth~
acrylates, acrylic acid, methacrylic acid, itaconic `"
acid, acrylonitrile and methacrylonitrile. Desirable
ethylenically unsaturated monomers copolymerizable with
the vinylidene chloride monomer are selected from the `;
group consisting of vinyl chloride, alkyl acrylate, and
alkyl methacrylates, the alkyl acrylates and alkyl meth-~`
acrylates having from 1 to 8 carbon atoms per alkyl
group. Preferably, the ethylenically unsaturated
monomer copolymerizable with the vinylidene chloride ~
monomer is selected from the group consisting of vinyl ~-
chloride, methyl acrylate, ethyl acrylate and
20 methylmethacrylate. ;
,, ;~. .,.;
The preformed polymer is selected to be
swellable in the monomer mixture and to be capable of `
25 having a sufficient amount of the monomers graft theretoi;
such that, upon polymerization, the preformed graft ;
copolymer provides improved impact strength to the
polymeric polyblend. By "swellable" is meant that the -
preformed polymer is capable of imbibing the monomer
mixture without dissolving therein. By "improved impact
strength" is meant that the polymeric polyblend having
the graft polymer has a higher impact strength than a
polymeric polyblend having the same components in an `~
ungrafted state.
' ` ;~ .' ;,.~. '
36,368-F -8- -~
~ '
.
- 9 -
The preformed polymer is suitably an olefin
polymer. The term "olefin polymer" includes
-- homopolymers and copolymers of a-monoolefins and sub-
stituted a-monoolefins, particularly a-monoolefins or
substituted a-monoolefins having from 4 to 12 carbon
atoms. Exemplary a-monoolefins homopolymers include
polyethylene (e.g., ultra-low density polyethylene, low
denQity polyethylene, linear low density polyethylene, ;
medium density polyethylene, high density polyethylene);
10 polypropylene; poly(butene-1), poly(isobutylene); poly(1 -
-pentene); poly(1-hexene); and poly(1-octene).
Substituted a-monoolefins include ethyl acrylate,
n-butyl acrylate, and i-butyl acrylate, and halogenated
a-monoolefin polymers such as vinyl chloride, chlori-
nated polyethylene and chlorinated polypropylene. In
such halo~enated a-monoolefin polymers, the halogen -~
bonded to the a-monoolefin polymer backbone supplies all ~ -
or part of the halogenated organic moiety. Generally,
such substituted a-monoolefin polymers contain from 1 to
40 weight percent of chlorine, preferably 5 to 25 weight
percent chlorine.
; It is also understood that "olefin polymer"
includes a-monoolefin/a-monoolefin copolymers such as
ethylene~propylene copoIymers and ethylene~butene-1 -
copolymers; a-monoolefin/substituted a-monoolefin
copolymers. ~
The a-monoolefins and substituted a-monoolefins ;-
may also be copolymerized with a variety of suitable
comonomers such as carbon monoxide and carboxylic acids - -
having from 3 to 8 carbon atoms (e.g., ethylene vinyl
acetate and ethylene acrylic acid); alkyl or haloalkyl
ester of carboxylic acid wherein alkyl or haloalkyl has
` ,`'.~"~''
36,368-F -9~
- 1o -
from l to 12 carbon atoms; a-alkenyl having 2 to 12 car-
bon atoms; acyl having l to 12 carbon atoms: carboxylate
having from l to 12 carbon atoms; alkoxyl having from l -~
to 12 carbon atoms, and aryloxy having from 6 to 12
carbon atoms. When employing an a-mono-
olefin/substituted a-monoolefin copolymer, the substi-
tuted a-monoolefins preferably constitute up to about 50
weight percent of the ~opolymer, with the remainder `
being a-monoolefin.
1 0
The term "polyolefin" includes polyesters and ~ ;~
copolyesters. Exemplary polyesters and copolyesters ; ;
include polyethylene terepthalate and copolymers ~
thereof. Polyethylene terepthalate includes (a) ;~ ;
15 polymers wherein at least about 97 percent of the ;~
polymer contains repeating ethylene terepthalate units
with any remainder being minor amounts of ester-forming
components, and (b) copolymers of ethylene terepthalate D .,'',"' ;.
Exemplary polyesters and copolyesters also `~
include Eastman PCCE copolyesters, which are
commercially available from Eastman Chemical Products,
Inc. PCCE copolyesters are characterized by melting
range of 195C to 215C. Specific PCCE copolyesters
include PCCE 9965 (1.28 inherent viscosity), PCCE 9964 ~ ~
(1.05 inherent viscosity), and PCCE 9967 (1.16 inherent ;
viscosity).
~ Conventional polymerization techniques, well-
-known to those skilled in the art, may be u~ed in pro~
ducing the polyesters and copolyesters used in this ~`~
invention.
36,368-F -10_
`. .
'',:;
Preferred olefin polymers include polyethyiene;
chlorinated polyethylene, ethylene/vinyl acetate copol-
ymers; ethylene~ethyl acrylate copo]ymers;
ethylene/acrylic acid copolymers; ethylene/propylene
copolymers; ethylene/carbon monoxide copolymers; and
polyesters and copolyesters. Polyethylene is the most
preferred.
It is understood that the preformed polymers
may contain polyblends of the above-described olefin
polymers. The polyblends may also contain at least one
olefin polymer and a nonolefin polymer, provided that at
least 5 percent of the monomer mixture is gra~ted to the
preformed polymer and the nonolefin polymer is
compatible with the olefin polymer.
.
Methods of forming the preformed polymer are
well-known to those skilled in the art. A general
description of methods suitable for the preparation of
the preformed polymers are set forth in the Kirk-Othmer
Encvclopedia of Chemical Technolo~v, 3rd edition (1980).
. .
The polymerizable mixture is suitably prepared -~
by phy ically mixing the preformed polymer with the
monomer mixture. Generally, the monomer will be imbibed
in the preformed polymer in an amount such that at least
5 weight percent, preferably 15 weight percent, most
preferably 30 weight percent, of the monomer mixture is
grafted to the preformed polymer after polymerization.
The amount of monomer mixture imbibed by the
preformed polymer is dependent on the temperature o~ the
polymerizable mixture, the size and shape of the ~ ~
preformed polymer, the length of time for which the ~ -;
,'",,''' ~.' .''
36,368-F _~
,:~
12- !
preformed polymer is allowed to contact the monomer
mixture, and. of course. the composition of the monomer
- mixture and the preformed polymer. In a preferred ' -
embodiment, the time and temperature employed in the
reaction are selected so that essentially all of the ;
monomer mixture is imbibed by the preformed polymer.
This is preferred because it allows for the formation of
a more intimate blend of the preformed polymer and the
polymer formed from the monomer mixture.
1 0
Generally, the preformed polymer will be ~
allowed to contact the monomer mixture for a period of ;
time of from Z0 to 2000 minutes, preferably from 240 to
1400 minutes. The preformed polymer will contact the
monomer mixture at a temperature of from 50C to 100C, ~
and preferably from 60C to 100C. ~-
The monomer mixture will be generally uniformly
imbibed within the preformed polymer, providing a rela~
tively homogeneous polymer blend. Consequently, the
graft sites between the preformed polymer and the poly-
mer formed from the monomer mixture are generally uni-
formly di~tributed throughout the graft copolymer. It
is preferred that essentially all of the monomer mixture
be imbibed by the preformed polymer, because it provides
a higher saturation of the preformed polymer with the ~ `
monomer mixture and the concomitant formation of a more
intimate blend of the preformed polymer and the polymer
30 formed from the monomer mixture. Typically, the graft ~
polymerization process involves polymerizing the ; ~; ;
monomers in the polymerizable mixture to chemically
combine or graft at least a portion of the polymerized
monomer mixture on the preformed polymer.
.. . ..
. ' '~ '
36,368-F -12- ~;
:.... ~:
,s~ =. . ,"~
- :
~ :
The polymerizable mixture is then polymerized
such that at least a portion o~ the polymerized monomer
-- mixture chemically combines or grafts on the preformed
polymer. The polymerizable mixture is suitably
polymerized through an emulsion or suspension
polymerization process. Emulsion and suspension polym-
erization processes are well-known. Generally, the
polymerizable mixture is emulsified or suspended in an
aqueous medium through the use of emulsifying or sus-
pending agentq. An initiator is then added to the
solution and polymerization of the monomers allowed to
proceed until achieving its desired degree of conYer-
sion.
, . . .
The polymeric polyblend may contain additional
additives well-known to those skilled in the art.
Exemplary of additives which may be incorporated in the
formulation are plasticizers; heat stabilizers; pro-
cessing aids; lubricants; light stabilizers such as
hindered phenol derivatives; pigments such as titanium
dioxide; and the like. Each of these additives is known
and several types of each are commercially available.
Blending of the components of the polymeric
polyblend can be accomplished by using conventional melt ~-
processing techniques for thermally sensitive polymers.
Exemplary melt processing equipment includes heated two-
-roll compounding mills, Brabender mixers, Banbury ~;~
mixers, single screw extruders, twin screw extruders,
and the like, which are constructed for use with
thermally sensitive polymers. See, for example, the
discussion by R. A. Wessling, in Chapter 11 of
Polyvinylidene Chloride, Vol. 5, Gordon and Breach
Science Publishers, New York, 1977, the teachings of -
''-`'"~"''', .`',"
,~
36,368-F -13-
. .: . ~ ~ . . .
: :. "::,: :~
' ' ' '~,"~' "-
. ~
!
-14- ~
" . -
which are incorporated herein by reference. Desirable ;~
results are obtained when an extruder, either single
screw or twin screw, is used.
In using conventional processing equipment for
thermally sensitive polymers, three conditions should be ~ -
met. Two conditions, which are interrelated, are
processing time and processing temperature. In melt ~
processing polymers, it is generally recognized that as --
processing temperatures increase, processing times must
decrease in order to avoid undesirable results such as
polymer degradation. -~
.
Melt processing must be accomplished at a ; `~
15 temperature below that at which decomposition of the ~ -
vinylidene chloride interpolymer becomes significant.
A third condition is that sufficient mixing
must be generated during melt processing to provide a
visually homogeneous blend with a reasonable mixing
time. Vinylidene chloride interpolymers may be melt
processed at temperatures of up to about 200C provided
processing time is less than about one minute. Temper-
ature~ greater than about 200C may be employed providedthe processing time is sufficiently short and provided
the vinylidene chloride polymer is not in contact with
iron or other metallic element~ known to catalyze the
degradation of vinylidene chloride interpolymers. For
30 example, vinylidene chloride polymers are melt process- ;
able at temperatures as high as about 230C at process-
ing times of less than about ten seconds when the
vinylidene chloride polymer forms an inner layer in a
coextruded structure. -
~'~' '"':
;
36,368-F _14_
, .
~" ': ~'
-15-
One factor in determining satisfactory mixing
times is the melt index of the components of the com-
patibilized blend. If component melt indexes are nearly
equal, a relatively short mixing time yields
satisfactory results.
A second factor in determining satisfactory
mixing times is mixing shear rate. All other parameters
being equal, a relatively low shear rate is needed when ~
10 the components have a relatively low viscosity or a high ;
melt index. Conversely, a relatively high shear rate is
needed when the components have a relatively high
viscosity or a low melt index.
A third factor in determining satisfactory -`~
mixing times is temperature. As noted hereinbefore, an ; -
upper limit on temperature is the temperature at which
decomposition of the vinylidene chloride interpolymer
becomes significant. A lower limit on temperature is ~
dictated by the polymer blend component which has the; ~;
greatest melting point. If the temperature does not - ~;
exceed the melting point of that polymer blend compo-
nent, a visually homogeneous melt will be difficult, if
25 not impossible, to obtain. ~--
. ' .. j.
A fourth factor in determining satisfactory ~`~`v
mixing times is mixing efficiency of the melt processing
equipment. Certain melt processing equipment mixes more~`-
30 efficiently than other melt processing equipment. -~
Selection of melt processing equipment which will pro~
duce a visually homogeneous melt within a reasonable
processing time is, however, not difficult and can be -
accomplished without undue experimentation. --
.' '."'
36,368-F -15- ; ~
. ::, ......
-16-
A fifth factor in determining satisfactory
mixing times is polymer feed form. The polymeric
-- components of the compatible blends are generally
available either in finely divided powder form or in
pellet form.
Methods of forming the polymeric polyblend into
pellets are well-known to those skilled in the art. Any
method capable of forming the polymeric polyblends into
pellets is suitable for use in the present invention.
For the purposes of this application, the terms ~
"pellet" or "pellets" refer to particles having a min- ~ -
imum cross-sectional dimension of at least 1/32 inch,
preferably of at least 1/16 inch, and most preferably of
at least 1/8 inch, said pellets suitably have a maximum
cross-sectional dimension of at least 1/2 inch,
beneficially of at least 3/8 inch, and preferably of at
least 1/4 inch. An e~emplary Method of forming the
polymeric polyblends into pellets includes extruding the
mixture through a strand die to form an extruded strand
and chopping the extruded strand into pellets.
The polymeric polyblends, in either powder or
25 pellet form, are suitably fabricated into sheets, films, -
container and the like. Articles formed from polymeric
polyblends according to the present invention possess
good barrier to the mass transport of atmospheric gases
and water vapor and possess impact strengths.
30 ' `
Further, such polyblends have good solvent
resistance. In other words, the polyblends are
resistant to absorbing and swelling with solvents,
making said polyblends particularly advantageous as
36,368-F -16~
: :
- -17-
packaging for such products as cooking oils and
gasoline.
The following examples are meant to be illus- ~:
trative only and are not intended to limit, in any man-
ner, the scope of the invention as set forth in the
claims.
Exam~les
0 Polymeric polyblends according to the present -.
invention are prepared with various components set forth ~.
below.
:, .,. ~:: :. .:,
Each of the polymeric polyblends used in the . ;
examples is coded and described hereinafter in Table I.
... .
-;
36,368-F -17-
. . .~ ..
TABLE I ~-
Polymer Components ~
Code Polymer :
PVdC-1 A polymeric composition containing 98% of a
vinylidene chloride copolymer, 1% Citroflex
A-4, a plasticizer commercially available
from Pfizer Chemical Co.; and 1% epoxidized
soybean oil, a plasticizer commercially
available from Pfizer Chemical Co. The
vinylidene chloride interpolymer is formed
from a monomer mixture comprising about 80 ~
weight percent vinylidene chloride and ~:
about 20 weight percent vinyl chloride, ~;
based on total monomer mixture weight. The -::::
copolymer has a major melting point of 162C .
and a weight average molecular weight of :
80,000.
20 PVdC-2 A polymeric composition containing 98% of a ::
vinylidene chloride copolymer, 1% Citroflex
A-4; and 1% epoxidized soybean oil, a plas-
ticizer commercially available from Pfizer ::
Chemical Co. The vinylidene chloride
interpolymer i~ formed from a monomer mix- :
ture comprising about 94 weight percent - ~ :
vinylidene chloride and about 6 weight per- -
cent methyl acrylate, based on total mono-
mer mixture weight. The copolymer has a :
3 major melting point of 165C and a weight
average molecular weight of 90,000. ;~
GC-1 A graft copolymer is formed by loading 2850
grams of a low density polyethylene resin, ~ ;:
,: . .~.,.,~,
36,368-F -18~
_19- -
commercially available from The Dow Chemi-
cal Company under the trade designation PE-
~ 641, into a ten-gallon stirred polymeriza~
tion reactor. To the polyethylene in the
reactor is added 13,000 grams of demineral-
ized water, 0.6 grams of di-tert-butyl-
methylphenol; 40 grams of tertiary butyl
peroctoate, 6150 grams of vinylidene chlo- ; -
ride, 1500 grams of vinyl chloride, 76
grams of epoxidized linseed oil and 17
grams of Methocel~K4M brand cellulose ether ~ ~ -
as a suspending agent.
The reactor is sealed, purged with nitrogen
and elevated to a temperature of about 25C.
The temperature is gradually raised for
about three hours until it reaches about
80C and polymerization is continued for an
additional 13 hours. The resultant -
polymeric material slurry is vacuum -
stripped and recovered. ;~ ~
GC-2 A graft copolymer is formed by repeating ~; `}
the procedures for preparing GC-1 with the ~ -^
exception that 3670 grams of low density
polyethylene, 5470 grams of vinylidene
chloride and 1360 grams of vinyl chloride
are employed instead of the amounts of the
same ingredients used in preparing CC-1.
GC-3 A graft copolymer is formed by repeating
the procedures used to form GC-1 with the
following exceptions: 2850 grams of Kodar
PETG 6763, a polyethylene terephthalate
(PETG) resin commercially available from --~
:.
36,368-F _19_ ~
.. ~,.,.;~ .
"~","''.''',""'`''
-20-
Eastman Chemical Co. , is loaded in place
of the polyethylene used in preparing G~
GC-4 A graft copolymer is formed by repeating
the procedures used to form GC-1 with the
following exceptions: 2850 grams of a PCCE :
9965, a copolyester resin commercially
available from the Eastman Kodak Company,
is loaded in place of the polyethylene used
in preparing GC-1.
GC-5 A graft copolymer is formed by repeating
the procedures used to form GC-1 with the
following exceptions: 3500 grams of a poly-
propylene resin, commercially available
from Himont Inc. under the trade designa-
tion PP Sb-751, is loaded in place of the
polyethylene; 12,000 grams of demineralized ~
water, 0.5 grams of di-tert-butylmethyl :
phenol; 20.0 grams of tertiary butyl per- : ~
octoate, 6580 grams of vinylidene chloride, : .
420 grams of methyl acrylate, 80 grams of
epoxidized linseed oil and 20 grams of
Methocel~K4M brand cellulose ether as a ~ ~:
suspending agent are e~ployed instead of
~ the amounts of the same ingredients used in
: preparing GC-1. ~;~
Polymeric compositions are formed by
30 blending various quantities of the vinylidene chloride ~.
interpolymer and the various graft copolymers from Table
The polymeric compositions are formed into
a generally homogeneous mixture by dry blending the -
36,368-F . -20- `~
'` ' ~ '
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components. The components are loaded in about 4 lb
batches into a Hobart mixer, and mixed for a period of
approximately 45 minutes.
The powdery mixtures are extruded through a
1 1/2" single screw extruder having a length to diameter
ratio of 12:1. The extruder has the following set
temperatures: (a) Zone 1 temperature = 170C; (b) Zone
2 temperature = 174C; and (c) a die temperature = 176C. ;~
From the extruder, the blends are passed to a strand die
and extruded into a water bath. From the extruder, the
blends are passed to a stranding die, and are extruded
into a water bath. The strand is then chopped into
pellets, and the pellets are compression molded into a
sample suitable for ASTM D-256, Method A.
Physical properties of the resultant polymeric
polyblends are determined and are set forth in Table II. -
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36,368-F -21~
-22-
TABLE II
Exam- Polymer Component Impact Oxygen
Code~ Amount~ Stren~th~ Permeability~
1 PVDC-1 65 1.18 0.39
GC-1 35
2 PVDC-1 42 1.40 0.54
GC-1 58
3 PVDC-1 20 1.58 0.92
GC-1 80
4 PVDC-1 65 0.98 0.68
GC-2 35
PVDC-1 42 1.12 0.72
GC-2 58
6 PVDC-1 65 1.25 0.81
GC-3 35 ~;
7 PVDC-1 65 1.46 0.92 -
GC-4 35
8 PVDC-2 15 1.12 0.94
GC-5 85
9 PVDC-2 30 0.96 0.63
GC-5 70
Polymer components aq set forth in Table I.
Amounts are in percentages based upon the total
weight of the polyblend.
~ Notched Izod Impact Strength in foot pounds per
2~ inch notch according to American Society of
Te ting and Materials Te~t Method D-256, method
A.
Oxygen Permeability in (cubic centimeters of ~b
oxygen) (mil of sample thickness)/100 square ~-
inches (day) (atmosphere of pressure). ~ ;;
As can be seen from the data in the above
table, polymeric polyblends of the present invention
h~ve a combination of good impact strength and good
oxygen permeability. ~ ~
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36,368-F -22- ~
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Although the invention has been described in `~-~
detail with reference to specific examples thereof, it :~
will be understood that variations can be made without ~ -
departing from the scope of the invention as described
above and as claimed below.
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