U.S. patent number RE34,537 [Application Number 07/947,607] was granted by the patent office on 1994-02-08 for plastic composite barrier structures.
This patent grant is currently assigned to E. I. Du Pont de Nemours and Company. Invention is credited to Edward J. Deyrup.
United States Patent |
RE34,537 |
Deyrup |
February 8, 1994 |
Plastic composite barrier structures
Abstract
Composite moisture and oxygen barrier structures in the form of
films, sheets, tubes and bottles are described which are composed
of foils of high density polyethylene and foils of polar oxygen
barrier resins adhered to each other with a coextruded bonding
resin composition composed of blends of predominantly high density
polyethylene containing low levels of a grafted unsaturated
dicarboxylic acid anhydride and linear low density polyethylenes
which are copolymers of ethylene with either octene-1 or butene-1.
The preferred dicarboxylic acid anhydride is maleic anhydride. The
oxygen barrier resins are preferably ethylene/vinyl alcohol
copolymers or amorphous polycarboxylamides from condensation
polymerization of aliphatic diamines and aromatic dicarboxylic
acids.
Inventors: |
Deyrup; Edward J. (North East,
MD) |
Assignee: |
E. I. Du Pont de Nemours and
Company (Wilmington, DE)
|
Family
ID: |
27378975 |
Appl.
No.: |
07/947,607 |
Filed: |
September 21, 1992 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
|
|
100191 |
Sep 23, 1987 |
4973625 |
|
|
Reissue of: |
530764 |
May 30, 1990 |
05039565 |
Aug 13, 1991 |
|
|
Current U.S.
Class: |
428/35.7;
428/36.6; 428/35.4; 428/520; 428/476.1 |
Current CPC
Class: |
B32B
27/08 (20130101); B65D 1/0215 (20130101); B32B
7/12 (20130101); Y10T 428/31928 (20150401); Y10T
428/1341 (20150115); Y10T 428/1379 (20150115); B32B
2323/043 (20130101); Y10T 428/1352 (20150115); Y10T
428/31746 (20150401); B32B 2323/046 (20130101) |
Current International
Class: |
B65D
1/02 (20060101); B32B 27/08 (20060101); B65D
023/00 (); B32B 027/08 () |
Field of
Search: |
;428/35.4,36.6,36.7,35.7,476.1,520,515,517,519
;525/74,70,78,207 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Robinson; Ellis P.
Assistant Examiner: Nold; Charles R.
Attorney, Agent or Firm: Lew; Jeffrey C.
Parent Case Text
This is a continuation of application Ser. No. 07/100,191, filed
Sept. 23, 1987, now U.S. Pat. No. 4,973,625.
Claims
I claim:
1. A coextruded composite packaging film comprising at least one
foil of a high density linear polyethylene adhered to at least one
foil of a polar, oxygen barrier resin with a melt extrudable
bonding resin composition, said oxygen barrier resin foil being
selected from the group consisting of ethylene/vinyl alcohol
copolymer, polyvinyl alcohol and polycarboxylamides, said melt
extrudable bonding resin composition consisting essentially of a
blend of from 70 to 90 weight percent of composition (i) and from
10 to 30 weight percent of composition (ii) wherein composition (i)
is composed of a blend of high density linear polyethylene having a
melt index in the range of from 0.1 to 8.0 g/10 min. and a density
in the range of from above 0.950 to 0.970 g/cm.sup.3 and sufficient
of a modified linear high density polyethylene having a density in
the range of 0.950 to 0.970 g/cm.sup.3 and a melt index in the
range of from 0.1 to 8.0 g/10 min. having from .[.0.7 to 14 mole.].
.Iadd.0.5 to 1 weight .Iaddend.percent of unsaturated dicarboxylic
acid anhydride grafted to a portion of said high density linear
polyethylene to provide from .[.0.245 to 1.05 mole.]. .Iadd.0.055
to 0.2 weight .Iaddend.percent of said grafted anhydride in said
composition (i), and wherein composition (ii) is a linear low
density polyethylene selected from the group consisting of linear
copolymers of ethylene with butene-1 and linear copolymers of
ethylene with octene-1 having a density in the range of 0.912 to
0.930 g/cm.sup.3 and a melt index in the range of 0.5 to 6.0 g/10
min.
2. A composite packaging film of claim 1 in which the melt
extrudable bonding resin is composed of 80 to 90 weight percent of
composition (i) and 10 to 20 weight percent of composition
(ii).
3. A composite packaging film of claim 2 in which the linear high
density polyethylene employed in composition (i) has a melt index
in the range of 0.8 to 2.5 g/10 min and a density in the range of
0.955 to 0.960 g/cm.sup.3 and in which the linear low density
polyethylene of composition (ii) has a density in the range of
0.917 to 0.920 g/cm.sup.3 and a melt index in the range of 1.0 to
2.5 g/10 min.
4. A composite packaging film of claim 1 in which the foil of
oxygen barrier resin is composed of an amorphous polycarboxylamide
which is the condensation polymerization product of
hexamethylenediamine and a mixture of terephthalic and isophthalic
acids.
5. A composite packaging film of claim 1 in which the foil of
oxygen barrier resin is composed of ethylene/vinyl alcohol
copolymer.
6. A composite packaging film of claim 1 composed of from two to
four foils of high density linear polyethylene having a polar,
oxygen barrier foil disposed between each high density linear
polyethylene foil and adhered on both sides of each polar oxygen
barrier foil to the adjacent high density linear polyethylene foil
with said melt-extrudable bonding resin composition.
7. A composite packaging film of claim 6 in which the foils of
oxygen barrier resin are composed of an amorphous polycarboxylamide
which is the condensation polymerization product of
hexamethylenediamine and a mixture of terephthalic and isophthalic
acids.
8. A composite packaging film of claim 6 in which the foils of
oxygen barrier resin are composed of ethylene/vinyl alcohol
copolymer.
9. A composite packaging film of claim 1 in which the foil of
oxygen barrier resin is composed of an ethylene/vinyl alcohol
copolymer and which contains, in addition, between said
ethylene/vinyl alcohol copolymer foil and an outer foil of linear
high density polyethylene, a foil extruded from a reground
composite packaging film of the composition of claim 1 adhered to
the foil of ethylene/vinyl alcohol copolymer with said bonding
resin composition.
10. A composite packaging film of claim 1 in which the foil of
oxygen barrier resin is composed of an ethylene/vinyl alcohol
copolymer and which contains, in addition, between said
ethylene/vinyl alcohol copolymer foil and an outer foil of linear
high density polyethylene a foil of ethylene/vinyl acetate
copolymer adhered to the foil of ethylene/vinyl alcohol copolymer
with said bonding resin composition.
11. A composite packaging film of claim 1 in which the foil of
oxygen barrier resin is composed of an ethylene/vinyl alcohol
copolymer and which contains, in addition, between said
ethylene/vinyl alcohol copolymer foil and an outer foil of linear
high density polyethylene, an additional foil of an ethylene/vinyl
acetate copolymer adhered to the foil of ethylene/vinyl alcohol
copolymer with said bonding resin composition.
12. A coextruded blown plastic bottle having one wall composed of
high density linear polyethylene adhered to the other wall composed
of an amorphous polycarboxylamide with a melt-extrudable bonding
resin composition consisting essentially of a blend of from 80 to
90 weight percent of composition (i) and from 10 to 20 weight
percent of composition (ii) wherein composition (i) is composed of
a blend of high density linear polyethylene having a melt index in
the range of from 0.8 to 6.0 and a density in the range of from
0.955 to 0.960 g/cm.sup.3 and sufficient of said high density
linear polyethylene having from .[.0.7 to 14 mole.]. .Iadd.0.5 to 1
weight .Iaddend.percent of an unsaturated dicarboxylic acid
anhydride grafted to a portion of said high density linear
polyethylene to provide from .[.0.245 to 1.05 mole.]. .Iadd.0.055
to 0.2 weight .Iaddend.percent of said grafted anhydride in said
composition (i), and wherein composition (ii) is a linear low
density polyethylene selected from the group consisting of linear
copolymers of ethylene with butene-1 and linear copolymers of
ethylene with octene-1 having a density in the range of 0.917 to
0.920 and a melt index in the range of 1.0 to 2.5 g/10 min.
13. A blown plastic bottle of claim 11 in which the unsaturated
dicarboxylic acid anhydride is maleic anhydride.
14. A blown bottle of claim 12 in which the amorphous
polycarboxylamide wall is composed of the condensation product of
hexamethylenediamine and a mixture of terephthalic and isophthalic
acids.
Description
BACKGROUND OF THE INVENTION
The variety of plastic composite structures have been proposed in
the past in which a polar, oxygen barrier resin is adhered to a
modified polyolefin resin, frequently a polyethylene resin, which
has been chemically modified by grafting varying amounts of an
unsaturated carboxylic acid or an unsaturated carboxylic acid
anhydride frequently a dicarboxylic acid anhydride, at various
levels to the polyethylene backbone by methods known in the art. In
some cases a polyethylene is bonded to a polar oxygen barrier resin
with an adhesive which is a modified polyolefin containing various
levels of grafted carboxylic acid or dicarboxylic acid anhydride
and usually also an amorphous olefin rubber, such as
ethylene-propylene diene rubbers, ethylene propylene copolymers, or
linear low density polyethylenes which provide toughening and
improve adhesion to polar substrates. Generally it has not been
possible to obtain both good adhesion of the polyolefin resin to
the polar resin and high moisture vapor barrier properties in the
polyolefin resin. It is known that high density polyethylene which
has a high crystallinity provides better moisture barrier
properties than low density polyethylene or linear low density
polyethylene or ethylene/propylene rubbers but there have been
problems in obtaining adequate adhesion of high density
polyethylene or modified high density polyethylene to polar oxygen
barrier resins. Frequently the unsaturated carboxylic anhydride
employed has been
chi-methylbicyclo(2.2.1)hept-5-ene2.3-dicarboxylic acid anhydride
or maleic anhydride, but many other anhydrides have been disclosed
in other patents Illustrative of these types of composite
structures known in the art are shown in U.S. Pat. No. 4,087,587.
Shida et al., U.S. Pat. No. 4,198,327, Matsumoto et al., U.S. Pat.
No. 4,230,830. Tanney et al., U.S. Pat. No. 4,409,364, Schmukler et
al., U.S. Pat. No. 4,460,646, Inoue et al., U.S. Pat. No.
4,487,885. Adur et al., and U.S. Pat. No. 4,510,286, Liu. Most
commonly, these patents disclose composite structures involving
carboxylic acid grafted ethylene polymers or a carboxylic acid
grafted polypropylene adhered to crystalline polycarboxylamide such
as nylon-6. In some cases, adhesion to superior oxygen barrier
materials such as EVOH (ethylene vinyl alcohol copolymer) are
described.
U.S. Pat. No. 4,416,944, Adur described composite structures of
modified polyethylene and polypropylene adhered to oxygen barriers
such as EVOH or nylon and also shows adhesion to high density
polyethylene of modified polyolefin compositions comprising high
density polyethylene having a density in the range of 0.94-0.97
g/cc, high density polyethylene grafted to
chi-methylbicyclo(2.2.1)hept5-ene-2,3-dicarboxylic acid anhydride
at a level of 1.5 weight percent together with a polypropylene
resin and a linear low density polyethylene resin having a density
in the range of 0.91-0.94 g/cc. The total amount of high density
polyethylene in the adhesive composition is stated to be in the
range of 20-60% by weight in the examples.
U.S. Pat. No. 4,481,262, Shida et al., describes composite
structures adhered to nylon-6 or ethylene vinyl alcohol copolymer
in which the hydrocarbon copolymer adhered to it is a composition
containing a linear low density polyethylene having carboxylic
anhydride grafted to it and blended with a variety of different
materials including ethyelne vinyl acetate copolymer, ethylene
methyl acrylate copolymer, low density polyethylene homopolymers or
linear low density copolymers In the adhesive compositions, the
grafted linear low density polyethylene comprises 10% and the other
materials 90% of the blend In the examples ethylene vinyl acetate
copolymer or an ethylene acrylate copolymer or an ethylene methyl
acrylate copolymer are illustrated as comprising 90% of the
adhesive blend but in one example a polyethylene having a density
of 0.94 g/cc was substituted for these copolymers and provided some
adhesion to nylon.
U.S. Pat. No. 4,460,632, Adur et al. discloses composite structures
in which an adhesive polyethylene blend is adhered to substrates
such as nylon, nylon-6, polyethylene or ethylene/vinyl alcohol
copolymer. The adhesive compositions disclosed are blends of a
medium density high pressure, free-radical polyethylene, a linear
low density polyethylene and a high density polyethylene graft to a
carboxylic anhydride such as
chi-methylbicyclo(2.2.1)hept-3-ene-2,3-dicarboxylic anhydride or in
one example maleic anhydride. In the adhesive compositions employed
in these composites, linear low density polyethylene comprises from
10-90% by weight according to the generic disclosure. The examples
show 10% of the grafted high density polyethylene and a total of
from 10-90% of the mixture of grafted high density polyethylene and
medium density polyethylene . It is shown that the grafted high
density polyethylene may contain a very wide range of acid
anhydride grafted to it generically stated as from 0.05-30 weight
percent.
Another patent of interest is Mito et al. U.S. Pat. No. 4,370,388.
This patent discloses adhesive compositions and composite
structures made from them. Broadly adhesive structures are
disclosed which contain from 97-50 parts by weight of a
polyethylene resin having a density in the range of 0.945-0.970
grafted with a dicarboxylic acid anhydride such as maleic
anhydride. 3-50 parts by weight of an ethylene/4-methyl-1-pentene
copolymer having an ethylene content of 93-99.9 mole percent and
0-20 parts by weight of a rubbery synthetic polymer or copolymer
The patent broadly discloses that the amount of the grafted monomer
in the grafted high density polyethylene may range from 0.001-10% ,
more preferably 0.02-5%. Comparative examples in which the
copolymer of ethylene/4-methyl-1-pentene copolymer was replaced
with an ethylene/hexene-1 copolymer or an ethylene/propylene
copolymer rubber are said to be unsatisfactory. The density of the
ethylene/4-methyl-pentene copolymer disclosed is from 0.910-0.945
g/cm.sup.3 or preferably 0.920-0.93 g/cm.sup.3. Primarily two layer
composites are contemplated in which, in addition to the adhesive
resin, nylon-6, nylon-66 and other similar crystalline nylons as
well as a variety of polyesters and saponified copolymers of
ethylene/vinyl acetate are contemplated. The only exemplified
grafted high density polyethylene employed is one containing 2% by
weight of maleic anhydride, a melt index of 7 g/10 min and a
density of 0.962 g/cm.sup.3.
In all of the above patents the peel strengths disclosed are
substantially impossible to relate to each other because they are
also dependent upon laminating conditions and unstated percentages
of carboxylic anhydride grafted to a polyolefin.
Generally peel strength for coextruded composites are not
shown.
SUMMARY OF THE INVENTION
The present invention is directed to coextruded composite
structures in the form of foils, sheets, tubes or blown bottles and
other containers which provide both excellent oxygen barrier
properties and excellent moisture barrier properties. The oxygen
barrier properties are provided by a polar resin selected from the
group consisting of ethylene/vinyl alcohol copolymers prepared by
saponification or hydrolysis of corresponding ethylene/vinyl
acetate copolymers, polyvinyl alcohol, and polycarboxylamides.
Moisture barrier properties are provided by a foil of high density
polyethylene and by an adhesive composition consisting essentially
of a blend of from 70-90 weight percent of a high density linear
polyethylene having a melt index of from 0.1-8.0 g/10 min and a
density in the range of from above 0.950 to 0.970 g/cm.sup.3 and
containing sufficient of a modified linear high density
polyethylene having a density in the range of 0.950 to 0.970
g/cm.sup.3 and a melt index in the range of from 0.1 to 8.0 g/10
min having from .[.0.7-14 mole.]. .Iadd.0.5 to 1 weight
.Iaddend.percent of an unsaturated dicarboxylic acid anhydride
grafted to a portion of the high density linear polyethylene to
provide from .[.0.245 to 1.05 mole.]. .Iadd.0.055 to 0.2 weight
.Iaddend.percent of said grafted anhydride in the high density
polyethylene composition and blended therewith a linear low density
polyethylene selected from the group consisting of linear
copolymers of ethylene with butene-1 and linear copolymers of
ethylene with octene-1 having a density in the range of from
0.912-0.930 g/cm.sup.3 and a melt index in the range of 0.5-6 g/10
min.
Particularly preferred oxygen barrier foils are EVOH and amorphous
polycarboxylamides such as the condensation polymerization products
of hexamethylenediamine and a mixture of terephthalic and
isophthalic acids, most particularly a mixture of 30% by weight
terephthalic with 70% by weight isophthalic acid.
Also provided by this invention is an improved melt-extrudable
bonding resin composition capable of adhering nonpolar high density
linear polyethylene (HDPE) in the form of foils, sheets, tubes or
blown bottles or other containers to polar oxygen barrier resins in
the form, respectively, of foils, sheets tubes or blown bottles and
which exhibits a combination of resistance to separation of the
nonpolar high density polyethylene from the polar oxygen barrier
resin and low moisture vapor transmission comparable to that of
high density linear polyethylene alone in which the bonding resin
compositions consists essentially of a blend of from 70-90 weight
percent, preferably from 80-90 weight percent of composition (i)
and from 10-30 weight percent, preferably from 10-20 weight percent
of composition (ii) in which composition (i) is composed of a blend
of high density linear polyethylene having a melt index in the
range of 0.1-8.0 g/10 min preferably in the range of from 0.8-2.5
g/10 min. and a density in the range of from 0.950-0.970
g/cm.sup.3, preferably in the range of from 0.955-0.960 g/cm.sup.3
and sufficient of a modified high density linear polyethylene
having a melt index in the range of from 0.1-8.0 g/10 min.
preferably in the range of from 0.8-2.5 g/10 min. and a density in
the range of from 0.950-0.970 g/cm.sup.3, preferably in the range
of from 0.955-0.960 g/cm.sup.3, having from .Badd..[.0.7-14
mole.]..Baddend. .Iadd.0.5 to 1 weight .Iaddend.percent of an
unsaturated dicarboxylic acid anhydride, preferably maleic
anhydride, grafted to the high density linear polyethylene to
provide from .[.0.245-1.05 mole.]. .Iadd.0.055 to 0.2 weight
.Iaddend.percent of the grafted dicarboxylic acid anhydride in
composition (i), and in which composition (ii) is a linear low
density polyethylene (LLDPE) selected from the group consisting of
linear copolymers of ethylene with butene-1 and linear copolymers
of ethylene with octene-1 having a density in the range of from
0.912-0.930 g/cm.sup.3, preferably in the range of 0.917-0.920
g/cm.sup.3, and a melt index in the range of from 0.5-6.0 g/10 min.
preferably in the range of from 1.0-2.5 g/10 min.
DESCRIPTION OF PREFERRED EMBODIMENTS
For many purposes the most satisfactory melt-extrudable bonding
resin compositions of this invention consist essentially of a blend
of from 80-90 weight percent of composition (i) and from 10-20
weight percent of composition (ii) in which composition (i) is
composed of a blend of high density linear polyethylene having a
melt index in the range of from 0.8-2.5 g/10 min and a density in
the range of from 0.950-0.960 g/cm.sup.3 and sufficient of a
modified high density linear polyethylene having a melt index in
the range of from 0.8 to 6.0 g/10 min and a density in the range of
from above 0.950 to 0.970 g/cm.sup.3 having from .[.0.7-14 mole.].
.Iadd.0.5 to 1 weight .Iaddend.percent of maleic anhydride grafted
to a portion of the high density linear polyethylene to provide
from .[.0.245-1.05 mole.]. .Iadd.0.055 to 0.2 weight
.Iaddend.percent of the grafted maleic anhydride in composition
(i), and in which composition (ii) is a linear low density
polyethylene selected from the group consisting of linear
copolymers of ethylene with butene-1 and linear copolymers of
ethylene with octene-1 having a density in the range of 0.917-0.920
g/cm.sup.3 and a melt index in the range of from 1.0-2.5 g/10
min.
Particularly preferred composite film structures are prepared from
high density linear polyethylenes having a density in the range of
0.955-0.960 g/cm.sup.3 and a melt index in the range of from about
0.8 to about 2.5 g/10 min as the moisture barrier layer and
ethylene/vinyl alcohol copolymers having an ethylene content in the
range of from 25 to 50 mole percent as the oxygen barrier layer and
coextruded with the preferred bonding resin compositions described
above between the polyethylene foil and the ethylene/vinyl alcohol
copolymer foil.
Methods for preparing the high density, linear polyethylenes and
linear low density polyethylenes, which are copolymers of ethylene
with alpha-olefins, employed as components of the bonding resins of
this invention are well known to those skilled in the art.
Generally, moderately low pressures are employed using as catalyst
the reaction product of a transition metal salt, usually a chloride
of titanium, vanadium or zirconium or vanadium oxychloride,
partially reduced with an organometallic aluminum or magnesium
compound such as an aluminum alkyl compound or a Grignard reagent.
These polymerizations may be conducted at temperatures above
130.degree. C. in solution or as slurries in a diluent at lower
temperatures. Methods of preparing the linear copolymers and
homopolymers of ethylene employed in the bonding resins of the
present invention are described inter alia respectively in Anderson
et al. U.S. Pat. No. 4,026,698 and in Anderson et al. U.S. Pat. No.
2,905,645 as well as in several patents of Karl Ziegler and his
associates.
Conventional low density, branched polyethylenes, prepared at high
pressures using free-radical initiators and which have both very
long branches and a variety of short branches, have not been found
to be as satisfactory as the linear low density copolymers of
ethylene with butene-1 or octene-1 as components of the bonding
resins of the present invention.
The composite films of this invention can be used as such for
wrapping foodstuffs or biological specimens and the like where it
is desired to prevent contact with oxygen diffusing in as well as
loss of moisture diffusing out, or they can be converted into bags
or pouches for packaging such materials. For particular uses the
composite packaging film of this invention will be composed of two
to four foils of high density linear polyethylene having a polar
oxygen barrier foil disposed between each high density linear
polyethylene foil and adhered on both sides of each polar oxygen
barrier foil to the adjacent high density linear polyethylene foil
with the melt-extrudable bonding resin of the present invention.
Particularly preferred composite packaging films of this invention
employ an ethylene/vinyl alcohol copolymer as the oxygen barrier
resin. Particularly preferred coextruded blown bottles of this
invention have one wall composed of high density linear
polyethylene adhered to the other wall composed of the amorphous
polycarboxylamide obtained as the condensation product of
hexamethylaminediamine and a mixture of terephthalic and
isophthalic acids with the bonding resin of this invention
coextruded between the interior and exterior walls to provide good
adhesion and further resistance to the passage of moisture vapor.
The blown bottles of this invention are useful for storing
chemicals which are sensitive to both moisture vapor and oxygen in
view of the good barrier resistance to those gases provided by the
composite wall structure of the present invention.
As is evident from the above description, the composites of this
invention can be used to manufacture packaging films which can be
used as such or converted into bags or pouches. They can also be
coextruded in the form of tubes for conveying liquids or gases
where it is desired to prevent contamination with both moisture
vapor and oxygen.
The melt-extrudable bonding resin compositions employed in the
composite structures of this invention may conveniently be prepared
by dry blending of the ingredients followed by melt blending
preferably in an extruder where the melt exiting the extruder is
quenched in water and cut into pellets. Generally these
compositions will contain a small amount of the order of 0.1% by
weight of an antioxidant, preferably a hindered phenolic
antioxidant.
The preparation of grafts of the unsaturated dicarboxylic acid
anhydrides on the high density linear polyethylene ingredient of
the composition can be accomplished by methods known to those
familiar with the art which consist of heating a mixture of the
high density polyethylene and the unsaturated dicarboxylic
anhydride in the presence of air, hydroperoxides or other free
radical initiators. Most suitable are the methods described in U.S.
Pat. No. 4,612,155. A convenient method for accomplishing the
grafting reaction is to first premix the dry ingredients and then
extrude the mixture through a heated extruder, cutting up the
extrudate to provide molding pellets However, other well known
mixing means such as a Brabender mixer, a Banbury mixer, roll mills
or the like may also be employed to produce the unsaturated
dicarboxylic acid anhydride grafted to the polyethylene chains.
While maleic anhydride is the preferred unsaturated dicarboxylic
acid anhydride employed in preparing the melt extrudable bonding
resins used in composite structures of this invention many other
unsaturated dicarboxylic acid anhydrides are known to persons
familiar to this art which will graft in a similar fashion and
provide similar adhesive properties. Particularly useful such
unsaturated dicarboxylic acid anhydrides include
chi-methylbicyclo(2.2.1)hept-5-ene-2,3-dicarboxylic acid anhydride
and bicyclo(2.2.1)hept-5-ene-2,3-dicarboxylic acid anhydride. It is
also known that carboxylic acids which readily form anhydrides
under grafting conditions such as maleic acid and fumeric acid can
be used to produce such grafts with polyethylene.
The coextruded laminated multilayer composite structures of this
invention can be produced by various means as known to those
skilled in this art. For example, such structures can be produced
by melting the individual components in separate extruders and
coextruding them through a single coextrusion die fed with the
separate molten components from the individual extruders. The
temperature of the bonding resin composition during the coextrusion
can be in the range of 130.degree. C. to 300.degree. C. but is
preferably in the range of about 150.degree. C. to 250.degree. C.
The temperature of the polar barrier resin must be above its
softening temperature but below the temperature where rapid
decomposition may occur. For EVOH (the saponified copolymers of
ethylene with vinyl acetate referred to herein as ethylene/vinyl
alcohol copolymer), the temperature should be in the range of
170.degree. C. to 260.degree. C., preferably between 180.degree.
and 240.degree. C. during coextrusion. For amorphous
polycarboxylamides produced from aliphatic diamines and aromatic
dicarboxylic acids, the temperature during coextrusion should be
above their glass transition temperatures, which are below
170.degree. C., preferably in the range of 170.degree. to
250.degree. C. The molten HDPE resin should be at a temperature in
the range of about 150.degree. C. to 250.degree. C. during
coextrusion.
The thickness of the various layers in composite films will vary
according to the intended application. The adhesive bonding resin
composition can vary from 0.00254 to 0.254 mm but most typically
will have a thickness in the range from 0.013 to 0.076 mm. The
polar oxygen barrier resin can vary in thickness from 0.0025 to
0.25 mm but most typically the thickness will be in the range from
0.025 to 0.076 mm. The HDPE moisture vapor barrier layer can be in
the range from 0.10 to 0.25 mm, most typically in the range from
0.11 to 0.17 mm. In the case of coextruded composite sheets or
tubing and blown bottles, thicker HDPE and polar oxygen barrier
layers generally are preferred in order to provide greater
structural rigidity and greater moisture and oxygen barrier
properties.
When designing composite structures of this invention for
particular applications, the following Table A will be useful as a
guide in determining the thicknesses of each layer needed to
provide the required moisture vapor and oxygen barrier properties
of the composite structures.
TABLE A ______________________________________ O.sub.2 TR O.sub.2
TR Material MVT* (20.degree. C. DRY)** (35.degree. C. 80% RH)**
______________________________________ Amorphous poly- 0.4 2.5 1.2
carboxylamide 70/30 6I/6T*** nylon 6 8.0 3.6 7.0 EVOH 0.7-2.1
0.005-0.02 0.35 HDPE 0.12 48 LLDPE 0.27
______________________________________ *(g .multidot. mm M.sup.2
/24 hr) **cc .multidot. mil .multidot. 100 m.sup.2 .multidot. day
.multidot. atm ***polycarboxylamide from hexamethylenediamine and a
mixture of 70% isophthalic and 30% teraphthalic acids
Various combinations of layers of (A) HDPE, (B) bonding resin and
(C) O.sub.2 barrier resin can be provided by the composite
structures of this invention. Examples are A/B/C, A/B/C/B/C/B/A,
A/B/C/B/A/B/C/B/A, A/B/C/B/A/B/C, C/B/A/B/C, A/B/C/B/A, etc.
Generally, if the composite structure will be used in the presence
of an atmosphere containing moisture, the O.sub.2 -barrier layer
should be protected on both sides with HDPE layers in cases where
moisture reduces significantly the O.sub.2 -barrier properties of
the polar resin as shown for EVOH in Table A. Also within the
composite structures of this invention are those which can be
represented as HDPE/CXA/oxygen barrier resin (e.g., EVOH) and
composite structures which can be represented by
HDPE/CXA/EVOH/CXA/EVA or regrind/HDPE in which CXA represents the
bonding resin. In the latter, EVA(ethylene/vinyl acetate copolymer)
or regrind (ground scrap composite film containing HDPE, CXA, and
EVOH) provides adhesion to the outer HDPE layer as well as adhering
to the CXA.
Unless otherwise stated, melt index values for the homopolymers and
copolymers described were determined by the procedure of ASTM
D-1238, Condition E. The melt index of the polymers is controlled
by the temperature of polymerization as well as by the use of
telogens such as hydrogen, as is well known to those skilled in the
art.
The density values for the homopolymers and copolymers described
were determined by the procedure of ASTM D-1505 on compression
molded films. The densities, and crystallinities corresponding
thereto, of the linear low density polyethylenes are controlled by
the weight percent of comonomer copolymerized with ethylene, as is
well known to those skilled in the art.
EXAMPLES
In the following Examples and Comparative Examples the following
abbreviations are used:
HDPEA represents a high density linear polyethylene having a
density of 0.960 g/cm.sup.3 and a melt index of 1.5 g/10 min.
HDPEB represents a high density linear polyethylene having a
density of 0.960 g/cm.sup.3 and a melt index of 8 g/10 min.
HDPEC represents a high density linear polyethylene having a
density of 0.958 g/cm.sup.3 and a melt index of 6.0 g/10 min.
LLDPEA is a linear low density copolymer of ethylene and octene-1
which has a melt index of 1.0 g/10 min and a density of 0.920
g/cm.sup.3.
LLDPEB is a linear low density polyethylene copolymer with octene-1
which has a melt index of 2.3 g/10 min and a density of 0.917
g/cm.sup.3.
LLDPEC is a linear low density copolymer of ethylene and octene-1
having a density of 0.912 g/cm.sup.3 and a melt index of 3.3 g/10
min.
LLDPED is a linear density copolymer of ethylene and octene-1
having a density of 0.912 g/cm.sup.3 and a melt index of 1 g/10
min.
LLDPEE is a linear low density copolymer of ethylene and octene-1
having a density of 0.92 g/cm.sup.3 and a melt index of 1.4 g/10
min.
LLDPEF is a linear low density copolymer of ethylene and butene-1
with a density of 0.92 g/cm.sup.3 and a melt index of 1.4 g/10
min.
LLDPEG is a linear low density copolymer of ethylene and butene-1
having a density of 0.92 g/cm.sup.3 and a melt index of 0.6 g/10
min.
EVOH F is an ethylene/vinyl alcohol copolymer having approximately
32 mole percent ethylene and a melt flow of 3 g/10 min at
210.degree. C.
EVOH E is an ethylene/vinyl alcohol copolymer having approximately
44 mole percent ethylene and a melt flow of 16 g/10 min at
210.degree. C.
CXA represents the melt extrudable bonding resin composition
employed to adhere the high density polyethylene to the polar
substrate which in these Examples is an ethylene/vinyl alcohol
copolymer represented by EVOH, the saponification product of the
corresponding ethylene/vinyl acetate copolymer or an amorphous
polycarboxylamide which is the reactive product of
hexamethylenediamine and a mixture of isophthalic and terephthalic
acids.
In Tables II, III and IV, HDPE represents high density polyethylene
employed as the nonpolar moisture vapor barrier in the composite
film. In these examples this was HDPEA.
GRAFT CODES D, E, G, H, P and S refer to the code set out in Table
I for the properties of the HDPE grafted resins.
GRAFT CODE T refers to 2.0% by weight maleic anhydride grafted to
EPDM rubber as set out in Table VII.
MVT represents moisture vapor transmission and is employed in Table
V with respect to the various compositions set out there. As shown
in Table V compositions which are principally HDPE have a low MVT
whereas compositions which are LLDPE solely have twice the moisture
transmission of HDPE compositions. The compositions of this
invention closely approximate the low values of 100% HDPE. These
moisture vapor transmission measurements were made on a Mocon
Permatian W at 37.8.degree. C. at 100% relative humidity. The MVT
values were obtained on approximately 5 ml extrusion cast films.
The Mocon reading was multiplied by the thickness of the cast film
to obtain the value reported in Table V.
CAL % MALEIC is the calculated % maleic anhydride that is in the
blend based on the amount of maleic anhydride in the graft and the
amount of graft used in the blend.
PEEL kg/cm refers to the peel strength in kg/cm as determined on a
1-inch wide strip cut from the center of the composite film
parallel with flow direction and then separated at a rate of 5
inches per minute on a universal testing machine The samples were
generally peeled within 4 hours after having been made.
In Examples 1-42 the adhesive blends were prepared by dry blending
the ingredients together by tumbling in a polyethylene bag followed
by melt blending in a 30 mm Werner Pfleiderer extruder which had
two sets of kneading blocks and three reverse bushings. The vacuum
port was maintained at 20 inches vacuum. Extruder barrel
temperatures were set at 180.degree. C., rpm was 200 and the
extrusion rate was 20 lbs per hour. The melt exiting the extruder
was quenched in water and then cut into molding pellets. Included
in the blends of Examples 1-42 was 0.1% of a hindered phenolic
antioxidant either Irganox 1010 (referred to as "10" in the Tables)
or Irganox 1076 (referred to as "76" in the Tables).
The blends were then evaluated as the coextruded middle adhesive
tie layer between a coextrusion of an ethylene vinyl alcohol
copolymer (EVOH) and a high density polyethylene, HDPEA. Each of
the graft modified polyethylene blend compositions listed in Tables
I-III was melted in a one inch extruder at 4-6 rpm and the molten
extrudate from that extruder was fed to a coextrusion die and
formed the innermost central layer. The molten cuter layer of EVOH
was fed to the coextrusion die by a 1.5 inch extruder operating at
approximately 10 rpm. The outer layer of HDPE was fed as a melt to
the coextrusion die by a 1.25 inch extruder operating at
approximately 15 rpm. The barrel temperatures of all extruders were
set at 230.degree. C. and the melt temperatures indicated by a melt
thermocouple in the die was 233.degree. C. The composite film
emerging from the die was wrapped around a heated drum which was at
a temperature of approximately 100.degree. C. The film width was
0.28 meter. The film take-up speed was 1.52 meters/min. The film
thicknesses of each layer of the composite structure are indicated
in Tables II, III, IV and VI.
Tables I lists the melt index and density of the grafted HDPE
polymers used in Tables II-VII.
In Tables II-VI the heading "Graft Code" refers to the code set out
in Table I for the grafted high density linear polyethylene having
maleic anhydride grafted onto it.
Referring to the Examples as set out in Table II, Comparison
Example I had a low peel strength because the melt index of the
graft ("S") was above the maximum permitted by the invention. In
Table III, Comparison Examples 2-5 had low peel strengths because
they contained inadequate amounts of the LLDPE component.
Comparison Example 6 had a low peel strength because again it
employed a graft ("S") having too high a melt flow. In Table IV,
Comparison Example 7 is primarily all LLDPEA; while its peel
strength is in a low range of the preferred HDPE blends, its
moisture vapor transmission rate (MVT) was too high and therefore
not within the invention. Comparison Examples 8 and 9 have low peel
strengths because there was insufficient amount of maleic anhydride
in the final blend.
TABLE 1 ______________________________________ PROPERTIES OF HDPE
GRAFTED RESINS Melt Code Density Index
______________________________________ D 0.960 5.47 E 0.956 0.80 G
0.960 1.40 H 0.956 0.65 P 0.960 2.49 S 0.960 12.50
______________________________________
TABLE II
__________________________________________________________________________
EXAMPLES 1-9 AND COMPARATIVE EXAMPLE 1 Patent HDPE LLDPE LLDPE
Graft Graft CAL % EVOH F CXA HDPE Peel Anti Example Type Type %
Code % Maleic mm Thick mm Thick mm Thick kg/cm Oxidant
__________________________________________________________________________
Comp 1 HDPEA LLDPEB 20 S 15.0 [0.150] 0.091 0.028 0.089 0.08 I10
0.170 Ex 1 HDPEA LLDPEB 20 H 9.5 0.095 0.099 0.020 0.112 0.58 I10
Ex 2 HDPEA LLDPEB 20 P 18.3 0.165 0.102 0.020 0.112 0.51 I76 Ex 3
HDPEA LLDPEB 20 P 14.6 0.131 0.102 0.020 0.112 0.47 I76 Ex 4 HDPEA
LLDPEB 12 P 18.3 0.165 0.102 0.020 0.107 0.40 I76 Ex 5 HDPEA LLDPEB
12 P 14.6 0.131 0.099 0.023 0.117 0.34 I76 Ex 6.sup.1 HDPEB LLDPEB
20 E 20.0 0.120 0.102 0.020 0.107 0.72 I10 Ex 7 HDPEB LLDPEB 20 D
24.0 0.120 0.086 0.016 0.117 0.68 I10 Ex 8 HDPEB LLDPEB 20 H 12.0
0.120 0.086 0.019 0.117 0.71 I10 Ex 9 HDPEB LLDPEB 20 D 24.0 0.120
0.107 0.021 0.132 0.44 I10
__________________________________________________________________________
TABLE III
__________________________________________________________________________
EXAMPLES 10- 17 AND COMPARATIVE EXAMPLES 2-6 Patent HDPE LLDPE
LLDPE Graft Graft CAL % EVOH F CXA HDPE Peel Anti Example Type Type
% Code % Maleic mm Thick mm Thick mm Thick kg/cm Oxidant
__________________________________________________________________________
Comp 1 HDPEA LLDPEA 5 P 14.6 0.131 0.066 0.025 0.140 0.25 I10 Comp
3 HDPEA NONE 0 P 21.9 0.197 0.076 0.018 0.142 0.22 I10 Comp 4 HDPEA
LLDPEB 5 P 14.6 0.131 0.071 0.025 0.122 0.21 I10 Comp 5 HDPEA NONE
0 P 14.6 0.131 0.089 0.023 0.122 0.16 I10 Comp 6 HDPEA LLDPEB 20 S
14.6 0.161 0.071 0.020 0.117 0.12 I10 Ex 10 HDPEA LLDPEB 30 P 14.6
0.131 0.069 0.015 0.122 0.89 I10 Ex 11 HDPEA LLDPEB 10 P 14.6 0.131
0.097 0.020 0.137 0.29 I10 Ex 12 HDPEA LLDPEB 20 P 14.6 0.131 0.071
0.018 0.130 0.51 I10 Ex 13 HDPEA LLDPEA 30 P 14.6 0.131 0.076 0.023
0.124 0.50 I10 Ex 14 HDPEA LLDPEB 20 P 7.3 0.066 0.081 0.020 0.122
0.45 I10 Ex 15 HDPEA LLDPEB 20 P 21.9 0.197 0.071 0.020 0.112 0.45
I10 Ex 16 HDPEA LLDPEA 20 P 14.6 0.131 0.084 0.020 0.145 0.40 I10
Ex 17 HDPEA LLDPEA 10 P 14.6 0.131 0.086 0.020 0.107 0.38 I10
__________________________________________________________________________
TABLE IV
__________________________________________________________________________
EXAMPLES 18-22 AND COMPARATIVE EXAMPLES 7-9 Patent HDPE LLDPE LLDPE
Graft Graft CAL % EVOH F CXA HDPE Peel Anti Example Type Type %
Code % Maleic mm Thick mm Thick mm Thick kg/cm Oxidant
__________________________________________________________________________
Comp 7 NONE LLDPEA 85.4 P 14.6 0.131 0.086 0.021 0.112 0.47 I10
Comp 8 HDPEA LLDPEB 30.0 P 3.3 0.030 0.091 0.021 0.112 0.06 I10
Comp 9 HDPEA LLDPEB 30.0 P 5.6 0.050 0.097 0.020 0.127 0.20 I10 Ex
18 HDPEA LLDPEA 20.0 P 14.6 0.131 0.102 0.020 0.127 0.36 I10 Ex 19
HDPEA LLDPEB 20.0 D 22.0 0.110 0.107 0.020 0.142 0.56 I10 Ex 20
HDPEA LLDPEB 30.0 P 14.6 0.131 0.086 0.020 0.127 0.78 I10 Ex 21
HDPEA LLDPEB 45.0 P 14.6 0.131 0.081 0.020 0.142 0.78 I10 Ex 22
HDPEA LLDPEB 20.0 P 14.6 0.131 0.102 0.018 0.142 0.64 I10
__________________________________________________________________________
TABLE V ______________________________________ EXAMPLES 23-30 7
COMPARATIVE EXAMPLES [10-25] 10-15 Patent MVT Ex- Base LLDPE LLDPE
Graft g mm/M.sup.2 / ample Resin Type % Code 24 HR
______________________________________ Comp HDPEA 0.138 10 Comp
HDPEA 0.104 11 Comp LLDPEA 0.273 12 Comp LLDPEA 0.276 13 Ex 23
HDPEA LLDPEA 9 D 0.132 Comp HDPEA LLDPEA 24 S 0.162 14 Comp HDPEA
LLDPEA 20 0.145 15 Ex 24 HDPEA LLDPEA 20 G 0.158 Ex 25 HDPEA LLDPEA
20 G 0.154 Ex 26 HDPEA LLDPEA 20 D 0.160 Ex 27 HDPEA LLDPEA 20 D
0.162 Ex 28 HDPEA LLDPEB 8 G 0.139 Ex 29 HDPEA LLDPEB 12 G 0.152 Ex
30 HDPEA LLDPEB 20 G 0.160
______________________________________
It is to be understood that the absolute values of the peel
strengths set out in the above Examples are dependent upon the
conditions under which the coextruded composite film structures
were made, upon the method and rate of testing the peel strength
and the thicknesses of the individual foils making up the composite
film structure and therefore cannot readily be compared with peel
strengths of such composite structures made under other
conditions.
EXAMPLES 31-42
The composite film structure of Examples 31-42 were prepared in the
same fashion as described for the composite film structures of
Examples 1-30. However, in these Examples the composition of the
bonding resin was varied by varying the type of LLDPE as shown in
Table VI.
In Table VI the heading "Struct Type" refers to the type of HDPE
used as the moisture barrier foil in the composite film structure.
The heading "Bar Type" refers to the type of EVOH employed.
TABLE VI
__________________________________________________________________________
Patent HDPE LLDPE LLDPE Graft Graft CAL % EVOH CXA mm HDPE mm Bar
Struct Peel Example Type Type % Code % Maleic mm Thick Thick Thick
Type Type kg/cm
__________________________________________________________________________
Ex 31 HDPEA LLDPEB 20 P 6.1 [0.099] 0.094 0.023 0.152 F HDPEA 0.91
0.055 Ex 32 HDPEA LLDPEB 20 P 12.2 [0.050] 0.117 0.025 0.163 F DPEA
1.16 0.110 Ex 33 HDPEA LLDPEC 20 P 12.2 [0.055] 0.127 0.025 0.163 F
HDPEA 0.77 0.110 Ex 34 HDPEA LLDPED 20 P 12.2 0.110 0.132 0.028
0.168 F HDPEA 0.65 Ex 35 HDPEA LLDPEE 20 P 12.2 0.110 0.117 0.028
0.163 F HDPEA 0.28 Ex 36 HDPEA LLDPEE 28 P 12.2 0.110 0.086 0.023
0.173 F HDPEA 0.71 Ex 37 HDPEA LLDPEF 20 P 12.2 0.110 0.107 0.025
0.152 F HDPEA 0.75 Ex 38 HDPEA LLDPEF 28 P 12.2 0.110 0.097 0.025
0.152 F HDPEA 1.07 Ex 39 HDPEA LLDPEG 20 P 12.2 0.110 0.112 0.025
0.152 F HDPEA 0.88 Ex 40 HDPEA LLDPEG 28 P 12.2 0.110 0.094 0.025
0.157 F HDPEA 0.93 Ex 41 HDPEB LLDPEB 20 P 12.2 0.110 0.091 0.025
0.107 E HDPEB 0.54 Ex 42 HDPEB LLDPEB 20 P 12.2 0.110 0.069 0.020
0.086 E HDPEB 0.87
__________________________________________________________________________
As can be seen from Table VI, Examples 38, 39 and 40, LLDPE made
from ethylene/butene-1 copolymer is equally effective as
ethylene/octene-1 copolymer for this component.
COMPARATIVE EXAMPLES 43, 44 AND EXAMPLE 45
Examples 43, 44 and 45 illustrate the preparation of blown bottles
having a composite structure; Example 45 has the composite
structure of this invention. Comparative Examples 43 and 44
illustrate other composite structure bottles where adhesion was not
satisfactory. The preparation of these bottles involved coextrusion
of a parison having high density polyethylene on the outside and an
amorphous polycarboxylamide prepared from the condensation product
of hexamethylenediamine and a mixture of 30% terephthalic acid and
70% isophthalic acid on the inside, with melt extrudable bonding
compositions between the two layers.
The conditions for extruding the parisons and blowing the bottles
for Example 45 were as follows:
The amorphous polycarboxylamide was extruded from a 50 mm single
screw extruder whose set temperatures was 221.degree. C. to
227.degree. C. except for the feed section which was 93.degree. C.
The HDPE was fed from 50 mm single screw extruder with 177.degree.
C. to 193.degree. C. barrel temperature except for the feed section
which was at approximately 66.degree. C. The extruder for the
coextrudable adhesive was a 38 mm single screw extruder. Barrel
temperatures were 177.degree. C. to 232.degree. C. except for the
feed section which was set at approximately 66.degree. C. These
extruders formed the multilayer parison with the polyamide on the
inside and the HDPE on the outside. The parison was blown into 32
oz Boston round cylindrical bottles with a weight of 686 40.+-.3g.
The HDPE layer of the bottle was 0.36 to 0.41 mm thick, adhesive
layer was 0.05 to 0.08 mm thick and the copolyamide layer was 0.08
to 0.10 mm thick. The cycle time per bottle was 14 seconds.
The parisons were blown into a mold which provided 32 oz Boston
round cylindrical plastic bottles having a weight of 40.+-.3 g. The
HDPE used as outer layer of the composite structure of the bottle
was HDPEC. HDPEC is a high density linear ethylene. The
polycarboxylamide layer provides excellent oxygen barrier
properties while the HDPE layer provides excellent moisture vapor
barrier properties. In Example 45, the middle layer of the bonding
resin composition provided both excellent adhesion and high MVT
resistance. Similar conditions were used to prepare the composite
bottles of Comparison Examples 43 and 44. In Comparison Examples 43
and 44, the bonding resins were ethylene/vinyl acetate copolymer
blended with EPDM rubber having maleic anhydride grafted to it and
which failed to give the high peel strength provided by a bonding
resin composition of the present invention. The compositions of
Examples 43, 44 and 45 are set out in Table VII.
The peel strengths in the machine direction (MD) and the transverse
direction (TD) were measured by cutting one inch wide strips in
those two directions from the blown bottles and then measured as
described for the peel strength measurements in Example 1-42.
TABLE VII
__________________________________________________________________________
COEXTRUDED COMPOSITE STRUCTURE BOTTLES Peel Strength Patent HDPE
LLDPE LLDPE Graft Graft CAL PCA** CXA HDPE kg mm Example Type Type
% Code Wt % % Maleic mm Thick mm Thick mm Thick MD TD
__________________________________________________________________________
Comp. (1) -- -- T 10 0.2 0.08-0.10 0.05-0.08 0.36-0.41 0.18 0.30 Ex
43 Comp. (2) -- -- T 5 0.1 0.08-0.10 0.05-0.08 0.36-0.41 0.16 0.16
Ex 44 Ex 45 HDPEC LLDPEB 20% P 14 0.126 0.08-0.10 0.05-0.08
0.36-0.41 CNS* CNS*
__________________________________________________________________________
*CNS = Could not separate. **PCA = Amorphous polycarboxylamide
70/30 6I/6T (1) Copolymer of ethylene with 18% vinyl acetate having
a melt index of 2.5 g/10 mm. (2) Copolymer of ethylene with 45%
vinyl acetate having a melt index of 0.8 g/10 mm.
A further test was made on the bottles of Examples 43 and 45. In
this test the bottles were filled four-fifths of the way to the top
with a mixture of 80% xylenes and 20% cyclohexanol The bottles were
stoppered and placed in an oven at 60.degree. C. and the peel
strength measured after various exposure times up to 100 hours
Table VIII sets out peel strength data for these bottles It is
evident that the bottle of Example 45 was particularly outstanding
in that even after 100 hours of this test the HDPE and
polycarboxylamide layers could not be separated.
TABLE VIII ______________________________________ PEEL STRENGTH
AFTER EXPOSURE OF 80% XYLENE/20% CYCLOHEXAMINE AT 60.degree. C.
Peel Strength (MD) Exposure Time kg/mm hours Comp. Example 43
Example 45 ______________________________________ 0 0.18 CNS* 8
0.12 CNS 24 0.08 CNS 100 0.17 CNS
______________________________________ *CNS = could not be
separated
Depending upon the intended use of the coextruded bottle, the
amorphous polycarboxylamide layer can form either the inside or the
outside layer of the composite structure bottle of Example 45; this
can be accomplished by extruding the parison with the
polycarboxylamide on the outside and the HDPE on the inside with
the bonding resin between and then blowing the parison into the
mold. Similarly, other oxygen barrier resins can be substituted for
the amorphous polycarboxylamide of Example 45. If desired, multiple
layer composite bottles can be made in accord with the invention,
for example by extruding a parison with HDPE on both the inside and
the outside with an oxygen barrier resin in between which is
adhered on both sides to the HDPE with layers of an extrudable
bonding resin of this invention when the parison is blown int the
bottle.
* * * * *