Polymer blends with enhanced properties

Polymer blends of a) polymers containing predominantly mers of(meth)acrylates and/or glutarimides with b) up to about 40 weight percent of polymers having greater than about 50 mol % vinyl alcohol mers exhibit useful barrier properties to oxygen and other environmental gases, while maintaining or enhancing physical properties and clarity.

FIELD OF THE INVENTION 
This invention relates to polymer blends of (meth)acrylate polymers, or 
glutarimides derived from such polymers, with polymers containing vinyl 
alcohol mers which are either miscible with, or form a discontinuous phase 
in, the poly(lower alkyl (meth)acrylate), glutarimide polymer, or other 
polymers which may be present. It further relates to such blends in the 
form of film, sheet, bottles, or other packaging articles. 
BACKGROUND OF THE INVENTION 
The packaging industry has long sought to develop plastic film, sheet, 
bottles, wrappings, and containers which are impervious to oxygen for 
preserving oxidizable materials and oxygen-sensitive foods and beverages. 
That industry has further sought to develop similar materials resistant to 
the passage of carbon dioxide for use in maintaining the carbonation of 
carbonated beverages. Resistance to passage of water vapor is also 
important to the packaging industry. No organic polymeric materials are 
truly impervious to gases; they all show some degree of permeability. 
Those which have low permeability to a particular gas are considered to be 
good barriers for that gas, while those which have high permeability are 
considered to be non-barrier materials with respect to that particular 
gas. The most useful polymers which exhibit very low values for oxygen 
permeability, i.e., are good barriers to oxygen, are poly(vinylidene 
chloride) and polymers containing vinyl alcohol mers, such as 
ethylene-vinyl alcohol copolymers containing less than about 50 mol 
percent ethylene units, or the homopolymers of hydrolyzed poly(vinyl 
acetate) known as poly(vinyl alcohol)s. 
Although each of these types of polymers is utilized in commerce, they have 
deficiencies which limit their broader use. Poly(vinylidene chloride) is 
thermally less stable than most polymers and is difficult to process; 
poly(vinyl alcohol)s are difficult to process, and their barrier 
properties are greatly affected by high relative humidity, and the 
ethylene-vinyl alcohol polymers, which are more easily processed than 
poly(vinyl alcohols not containing ethylene, are also sensitive to 
moisture, and are not optically clear. Further, the structural properties 
required for many applications are difficult to achieve with these 
polymers. 
The packaging industry has also sought to prepare containers exhibiting 
enhanced service temperature for the hot-fill packaging of foods, 
sterilization prior to packaging, autoclaving to sterilize contents, and 
the like. Materials attractive for such heat-sensitive uses tend to have 
poor barrier properties. 
Polymers based on lower alkyl methacrylates, such as poly(methyl 
methacrylate) exhibit clarity, have some degree of toughness, and can be 
compounded with impact modifiers to improve toughness, but do not exhibit 
satisfactory barrier properties. Conversion by reaction with lower alkyl 
amines or ammonia to polymers with mers of glutarimide improves the 
barrier properties significantly, but they still do not meet the 
requirements of the most demanding barrier applications. Kopchik, U.S. 
Pat. No. 4,246,374, discloses such polymers in thermally stable form, and 
discloses that their barrier properties are superior to most clear 
thermoplastics. 
Hallden-Abberton et al., in U.S. Pat. No. 4,727,117, describe a means of 
reducing the content of unreacted acid and anhydride groups of glutarimide 
polymers to prepare novel polymers of even higher thermal stability. In 
that patent, an extensive list of polymers with which such acid-content 
reduced glutarimides may be blended is given. Among these polymers are 
listed ethylene-vinyl acetate polymers and polyvinyl alcohol. 
Ethylene-vinyl alcohol polymers have not been disclosed for this use, and 
there is no suggestion in the prior art that the permeability behavior of 
such blends would differ in any way from an expected average performance, 
nor that the resulting blend would be particularly useful in barrier 
packaging applications. There is further no suggestion that blends of a 
second polymer with the acid-reduced polyglutarimides could be admixed 
with the polymers containing vinyl alcohol mers to obtain the barrier 
properties of the present invention. 
Blends of ethylene-vinyl alcohol polymers with vinyl alcohol contents 
greater than about 50 mol percent have been noted in the patent literature 
as components of blends with certain matrix polymers, such blends having 
attractive barrier properties. Particularly noted as matrices are 
poly(vinyl chloride) in U.S. Pat. No. 4,003,963, poly(ethylene 
terephthalate) in U.S. Pat. No. 4,284,671, and polypropylene in U.S. Pat. 
No. 4,362,844. These patents do not suggest the use of ethylene-vinyl 
alcohol copolymers with acrylic or glutarimide polymers for such purposes, 
nor do they disclose unexpected improvement in barrier properties at low 
levels of the ethylene-vinyl alcohol copolymer in the blend. 
Particularly noted is the intensive study of polyamide blends with 
ethylene-vinyl alcohol resins. U.S. Pat. No. 4,427,825 teaches such 
blends, wherein there are regions of the ethylene-vinyl alcohol copolymer 
having an average diameter of less than 50 nanometers in the polyamide. 
These compositions, as do those of the blends noted in the previous 
paragraph, exhibit a linear relationship for permeability behavior which 
is expected for such blends and which is demonstrated by a straight-line 
plot when the permeability is plotted as the ordinate on semi-logarithmic 
paper with ethylene-vinyl alcohol content as the abscissa. 
One known exception to this additive relationship of the linear logarithm 
of permeability is the disclosure in U.S. Pat. No. 4,410,482 of blends of 
a polyolefin matrix and a modified or dispersed nylon polymer, in which 
the nylon is processed to form laminar domains in the matrix. Such blends 
exhibit barrier properties against hydrocarbon liquids and gases 
substantially improved over that predicted for a homogeneous blend. 
Processes are also taught for the incorporation into the polyolefin matrix 
of dispersed similar platelets of other polymers, such as polycarbonate 
and poly(butylene terephthalate). This patent does not teach or suggest 
the utility of ethylene-vinyl alcohol to form laminar structures in 
poly(glutarimides); indeed, it requires a solvent or a dispersant polymer 
to obtain the laminar structures, whereas the present invention achieves 
the desired structure by a conventional thermal/mechanical history of 
mixing. This patent also does not teach or suggest that the combination of 
ethylene-vinyl alcohol or poly(vinyl alcohol) polymers within a 
polyglutarimide matrix will produce unexpectedly good resistance to the 
passage of gases. Further, the platelet or laminar morphology shown by 
this patent does not necessarily correspond with the morphology of the 
present blends; in some examples of improved barrier properties 
exemplified herein, the vinyl alcohol (co)polymer is finely dispersed in 
very small particles uniformly throughout the glutarimide matrix, and in 
others, the vinyl alcohol (co)polymer blend with the glutarimide or 
poly(lower alkyl) methacrylate matrix polymer shows optical clarity, a 
single glass-transition temperature, and/or other indicators of blend 
compatibility. Certain blends at relatively high levels of certain 
ethylene-vinyl alcohol copolymers do produce a laminar structure with 
excellent barrier performance. 
European Patent Application No. 273,897 discloses blends of polyethylene 
terephthalate with styrene-maleic anhydride as blow-molded containers 
having an oriented crystalline continuous phase of polyethylene 
terephthalate containing dispersed ovoid particles of the styrene 
copolymer, the ovoids having a diameter of 0.1 to 0.8 .mu.m and a length 
of 0.3 to 2 .mu.m. The microstructure is reported to impart physical 
properties suitable for containment or protection against permeation of 
gases or organic fuels. 
A publication in Research Disclosure, October, 1988, page 726, discusses 
the barrier properties of blends of poly(ethylene naphthalene carboxylate) 
with relatively low levels of ethylene-vinyl alcohol copolymers. This 
publication states that the actual values for oxygen permeability in such 
blends are four to five times lower than predicted from calculations of 
the effective permeability of the ethylene-vinyl alcohol copolymer from 
PET data. These data, while not calculated against a pure ethylene-vinyl 
alcohol polymer standard and thus not directly comparable with the data of 
the present invention, do show an unexpected improvement in a manner also 
demonstrated herein. The composite materials of the reference are opaque; 
the domains which are necessary to lower the oxygen permeability must be 
large enough to eliminate the clarity of the blends and thus destroy one 
of the particularly useful properties of the matrix polymers. 
It is thus an object of the present invention to prepare a blend of 
polymers having outstanding barrier properties to oxygen, carbon dioxide 
and moisture from one or more polymers having certain desirable physical 
properties but inadequate gas barrier properties of their own, and a 
polymer with vinyl alcohol mers which has excellent barrier properties. 
Another object is to prepare such a barrier blend structure further having 
excellent optical properties, resistance to impact, a service temperature 
sufficient for hot-fill and sterilization, and/or other desirable physical 
properties. Further objects and advantages will be apparent from the 
following description of the present invention. 
SUMMARY OF THE INVENTION 
We have discovered polymer blends comprising from about 20 to about 95% by 
weight of a first polymer containing at least 50 mole percent mers of one 
or more of lower alkyl (meth)acrylates and glutarimides and forming a 
continuous phase, from about 2.5% to about 40% by weight of a second 
polymer having at least 50 mole percent vinyl alcohol mers which is either 
miscible with, or forms a discontinuous phase in, the continuous phase, 
and up to about 75% by weight of one or more additional thermoplastic 
polymers compatible with the continuous phase. These blends have good 
barrier properties to gases, and other useful physical and optical 
properties. We have further discovered a process for improving the 
gas-barrier properties of polymers containing at least 50 mole percent 
mers of lower alkyl (meth)acrylate, glutarimide or a mixture of the two, 
which polymers may have only moderate gas barrier properties themselves, 
which comprises blending these polymers with the second polymer having at 
least 50 mol percent vinyl alcohol mers. The polymer blends may be formed 
into a film, sheet, molded article, container or packaging material.

DETAILED DESCRIPTION OF THE INVENTION 
The term "mer" as used herein means a combination of elements which, when 
polymerized by addition polymerization, forms a single repeating unit in a 
polymer. Thus the monomer ethylene (CH.sub.2 .dbd.CH.sub.2) becomes the 
mer ethylene (--CH.sub.2 --CH.sub.2 --) in polyethylene, even though the 
ethylenic double bond is no longer present in the polymer. The mer may be 
hypothetical, as in a vinyl alcohol mer present in hydrolyzed poly(vinyl 
acetate). More than one mer is present in a copolymer. Mers may be formed 
by post-reaction on a polymer, such as in a N-methyl dimethylglutarimide 
mer formed by the addition of methylamine to two neighboring mers of 
methyl methacrylate accompanied by the loss of two molecules of methanol. 
The term (meth)acrylate, as used herein refers to an acrylate ester, a 
methacrylate ester, a mixture of the two, or mers of an acrylate ester, a 
methacrylate ester or a mixture of the two. Similarly, (meth)acrylamide 
refers to acrylamide, methacrylamide, a mixture of the two, or mers of 
acrylamide, methacrylamide or a mixture of the two. 
In the present specification, the term "glutarimide" or "glutarimide 
polymer" refers broadly to polymers containing the cyclic group or mer of 
formula I, 
##STR1## 
where R.sup.1 and R.sup.2 may be H or lower alkyl, preferably both R.sup.1 
and R.sup.2 being methyl, and R.sup.3 is hydrogen, alkyl, aryl, alkaryl, 
or aralkyl. The term "lower alkyl", as used herein, means alkyl groups 
having from one to six carbon atoms, such as methyl, ethyl, n-propyl, 
sec-propyl, n-butyl, isobutyl, pentyl, hexyl, cyclohexyl and the like. 
Substituents may be present on the R.sup.3 groups, such as hydroxy, 
halogen, such as chlorine or fluorine, and the like. Preferably, R.sup.3 
is lower alkyl of from one to four carbon atoms, and more preferably 
methyl. The glutarimide group may be the sole repeating unit or mer in the 
polymer, or the polymer may contain other mers, preferably those of an 
alkyl (meth)acrylate, and more preferably methyl methacrylate. Other mers, 
such as those from styrene, .alpha.-methylstyrene, vinyl chloride, 
(meth)acrylic acid, (meth)acrylic anhydride, (meth)acrylamides, such as 
(meth)acrylamide, N-methyl (meth)acrylamide, N,N-dimethyl 
(meth)acrylamide, and the like, other (meth)acrylic esters, 
(meth)acrylonitrile, N-substituted maleimides where the substituted group 
is R.sup.3, and the like may also be present. While the glutarimide 
polymer may contain smaller proportions of glutarimide mers and still be 
within the invention as contemplated, a preferred glutarimide polymer 
contains at least about 50% mers of glutarimide, and a more preferred 
glutarimide polymer contains at least about 80% mers of glutarimide. 
The glutarimide polymer may be prepared by any of the methods known to 
those skilled in the art, such as by the reaction at elevated temperature 
of (meth)acrylic ester polymers or (meth)acrylic acid-(meth)acrylic ester 
copolymers with ammonia, an amine, urea, or a substituted urea, by 
reaction of poly((meth)acrylic anhydride) with ammonia or an amine, by 
thermal reaction of a (meth)acrylic ester-(meth)acrylamide copolymer to 
form the imidge ring, or by reaction in solution or in the melt of a 
polymer containing a high proportion of (meth)acrylic ester groups with 
ammonia or an amine. Preferred glutarimides are prepared by the method 
taught in U.S. Pat. No. 4,246,374, in which a 
(meth)acrylic-ester-containing polymer is reacted with an amine at 
elevated temperatures in a devolatilizing extruder. The glutarimide 
polymer may be of weight-average molecular weight from about 10,000 to 
about 10,000,000. A preferred molecular-weight range for retention of 
properties and ease of processing is from about 50,000 to about 200,000. 
Polymers containing mers of formula I which have limited thermal stability 
resulting from the presence of relatively large amounts of acid, anhydride 
or other de-stabilizing components may be used in the present invention, 
but they will be less desirable because of deficiencies in processing and 
use. 
The poly(glutarimide) may be further post-treated to reduce or remove acid 
and/or anhydride groups by treating it with reagents that eliminate such 
groups, such as, for example, dimethyl carbonate; these reduced-acid 
polymers are preferred, but polyglutarimides containing acids and/or 
anhydrides are also useful in the present invention. 
Also useful in the present invention as the first polymer are polymers 
containing at least about 50 mole percent of mers of a lower alkyl 
(meth)acrylate, preferably methyl methacrylate, but including mers such as 
methyl acrylate, ethyl acrylate or methacrylate, butyl acrylate or 
methacrylate, hexyl methacrylate or methacrylate, cyclohexyl acrylate or 
methacrylate, and the like. The first polymer may also include mers of 
such monomers as substituted alkyl acrylates and methacrylates, such as 
.beta.-hydroxyethyl methacrylate, .beta.-hydroxypropyl acrylate, and the 
like, vinyl heterocyclic monomers, such as 4-vinylpyridine, 
2-vinylpyridine, N-vinylpyrrolidone, N-vinylimidazole, 2-vinylthiophene 
and the like, unsaturated carboxylic acids, such as methacrylic acid, 
acrylic acid, acryloxypropionic acid, and the like, vinyl aromatic 
monomers, such as .alpha.-methylstyrene, styrene, .rho.-hydroxystyrene, 
and the like, maleic anhydride, maleimide, N-alkyl maleimides, N-aryl 
maleimides, vinyl acetate, acrylonitrile, and other vinyl, vinylidene or 
maleic monomers. Preferred are polymers with at least 80 mol % 
(meth)acrylate mers. Especially preferred are polymers containing at least 
90% (meth)acrylate mers. As used herein with respect to mers, the terms "a 
preponderance" and "predominantly" are used to mean a mol percentage 
greater than 50%. 
The lower alkyl (meth)acrylate polymer useful for preparing the 
glutarimide, for incorporating (meth)acrylate mers into the 
glutarimide-containing polymer, and as the first polymer containing at 
least about 50 mole percent of lower alkyl (meth)acrylate mers, may be 
prepared, using various ionic or free-radical methods, to a weight-average 
molecular weight from about 10,000 to about 10,000,000. A preferred range 
for retention of properties and ease of processing is from about 50,000 to 
about 200,000. A preferred process for manufacture uses a continuous-flow, 
stirred-tank reactor, but other polymerization processes which will be 
readily apparent to those skilled in the art, including suspension, bulk, 
or emulsion may be employed. The polymer may contain stabilizers, such as 
against ultraviolet light or heat degradation, and other additives such as 
processing aids, dyes and the like which are well known to those skilled 
in the art. 
Another preferred embodiment of the first polymer is a copolymer of methyl 
methacrylate with up to about 30 mole percent, and more preferably from 
about 20 to about 30 mole percent, of one or more of styrene, 
.alpha.-methylstyrene, .rho.-hydroxystyrene, (meth)acrylic acid, 
(meth)acrylic anhydride, (meth)acrylamide, maleic anhydride, maleimide, 
cyclohexyl (meth)acrylate, N-alkylmaleimides, N-arylmaleimides, 
4-vinylpyridine, or N-vinylpyrrolidone. 
A polymer containing at least 60% of mers of the glutarimide of formula I 
where R.sup.1 =R.sup.2 =R.sup.3 =methyl is one preferred embodiment of the 
first polymer. Such a polymer, either acid-reduced or non-acid reduced, 
will exhibit a Vicat softening temperature greater than about 140.degree. 
C. 
The second polymer containing at least about 50 mole percent vinyl alcohol 
mers is preferably a poly(vinyl alcohol), an ethylene-vinyl alcohol 
copolymer, or a copolymer of vinyl alcohol mers with long-chain alkenoxy 
methacrylate mers. The poly(vinyl alcohols) may be made by hydrolysis of 
poly(vinyl acetate), and can be obtained commercially with varying degrees 
of hydrolysis. The resulting polymers are copolymers containing mers of 
vinyl alcohol and vinyl acetate. The preferred poly(vinyl alcohols) 
contain at least about 80 mole percent mers of vinyl alcohol. The 
preferred alkenoxy methacrylate mers are those which terminate in 
hydrogen, C.sub.1 -C.sub.20 alkyl, C.sub.6 aryl or C.sub.7 -C.sub.30 
alkaryl groups. 
Because polymers of vinyl acetate which have been extensively or completely 
hydrolyzed to poly(vinyl alcohol) are quite sensitive to water and exhibit 
barrier properties influenced by the equilibrium moisture content, it is 
preferred in the present invention, as it is generally in the known art of 
barrier resins, to utilize copolymers wherein the vinyl alcohol group is 
present along with some less hydrophilic mers. Such mers may be 
(meth)acrylic esters, olefins, and the like, and mers of styrene and 
substituted styrenes grafted to the polymer. Preferred because of ease of 
synthesis and control of the extent of vinyl alcohol mers are hydrolyzed 
copolymers of ethylene. The ethylene-vinyl alcohol copolymers may be made 
by hydrolysis of an ethylene-vinyl acetate copolymer, or can be obtained 
commercially. They contain from about 15 to about 50 mole percent ethylene 
mers, and more preferably from about 25 to about 50 mole percent ethylene 
mers, at least about 50 mole percent vinyl alcohol mers, and may contain 
additional vinyl mers, as for example residual vinyl acetate mers. 
The second polymer may be present at amounts up to about 40% by weight of 
the blend, more preferably from about 5% to about 40% by weight, and still 
more preferably from about 5% to about 35% by weight. At levels below 
about 5% the enhanced barrier properties are difficult to discern, and 
above about 40% the undesirable physical properties of the vinyl alcohol 
polymer may degrade the physical properties of the blend. 
The blend of glutarimide or (meth)acrylate first polymer and second polymer 
containing at least 50 mole percent vinyl alcohol mers may further contain 
one or more other thermoplastic polymers with which the first polymer is 
known to be compatible, to form a multipolymer blend. The other 
thermoplastic polymers include polymers such as 
butadiene/styrene/(meth)acrylic, styrene/(meth)acrylic, and (meth)acrylic 
multistage polymers (as used herein "-" indicates blended polymers, "/" 
statistical or random copolymers, and "//" graft or block polymers); 
butadiene/styrene rubbers, ethylene/propylene/diene rubbers, polyamides, 
polyamide-multistage polymer blends (as used herein the multi-stage 
polymer may be a rubber grafted with a compatibilizing polymer and useful, 
for example, for imparting improved impact resistance to polymers), 
ethylene/vinyl acetate, styrene/acrylonitrile, 
styrene/acrylonitrile-multistage polymer blends, 
styrene/acrylonitrile-ethylene/propylene/diene rubber blends, 
.alpha.-methylstyrene/acrylonitrile, 
.alpha.-methylstyrene/styrene/acrylonitrile, .alpha.-methylstyrene/methyl 
methacrylate/ethyl acrylate, butadiene//acrylonitrile/styrene, 
polycarbonate, polycarbonatemultistage polymer blends, polybutylene 
terephthalate, polybutylene terephthalate-polycarbonate blends, 
polybutylene terephthalatemultistage polymer blends, polybutylene 
terephthalate/polytetrahydrofuran, polyvinyl chloride, polyvinyl 
chloride-multistage polymer blends, polyvinyl chloride-(meth)acrylate 
blends, chlorinated polyvinyl chloride, 
acrylonitrile/(meth)acrylate/styrene, epichlorohydrin/bisphenol-A, 
polyethylene terephthalate or other polyalkylene terephthalate, 
polyethylene terephthalate-glycol modified, polyethylene terephthalateacid 
modified, polyethylene terephthalate-polycarbonate blends, 
polycaprolactone, polyarylate, copolyester of bisphenol-A with isophthalic 
and/or terephthalic acids, poly(meth)acrylates, polyacetal, polystyrene, 
poly(.rho.-hydroxystyrene), high-impact polystyrene, styrene/maleic 
anhydride, styrene/maleimide, polyolefins, polyvinylidene fluoride, 
polyvinylidene fluoride-multistage polymer blends, cellulosics, 
polyethylene oxide, polyamideimide, polyetherester, polyetheresteramide 
and polyetheramide. The amount of blended other polymers may be up to 
about 75% by weight of the total multi-polymer blend; above that level the 
improved barrier properties may be seriously degraded, and below about 5% 
little effect is seen. A preferred range for the blended other polymers is 
from about 5 to about 50% by weight, and more preferred is from about 5 to 
about 30% by weight of the total multi-polymer blend. The blended other 
polymers may have moderately good barrier properties, such as 
poly(ethylene terephthalate) or poly(.rho.-hydroxystyrene), or may be 
relatively poor in barrier properties, such as polycarbonate. The blended 
other polymers may chemically combine with the first polymer, as occurs 
under certain melt conditions with polymers of caprolactam and 
poly(N-methyl)dimethylglutarimide containing residual acid and anhydride 
groups. 
In most cases the blended other polymers may exhibit good, but not 
unexpectedly good, barrier performance when blended only with the second 
polymer containing at least about 50 mole percent vinyl alcohol mers. At 
levels of the blended other polymers above 75%, the blend may lose the 
beneficial effects on barrier properties contributed by the binary blend 
of acrylic or glutarimide polymer with the polymer having vinyl alcohol 
mers, while below about 5%, the blended other polymers contribute little 
useful in non-barrier, physical properties, such as toughness, 
reinforcement, and the like. 
Thus, multi-polymer blends of the present invention preferably contain from 
about 20 to about 95% by weight of (A) the first polymer containing at 
least about 50 mole percent of mers of one or both of lower alkyl 
(meth)acrylate and N(lower-alkyl)glutarimide and forming a continuous 
phase, from about 2.5 to about 40% by weight of (B) the second polymer 
containing at least about 50 mole percent of vinyl alcohol mers and 
miscible with, or forming a discontinuous phase in, the continuous phase, 
and up to about 75% by weight of (C) the blended other polymers. A more 
preferred blend is from about 30 to about 95% of (A), from about 5 to 
about 40% of (B), and up to about 30% of (C), and a still more preferred 
blend is from about 40 to about 70% by weight of (A), from about 10 to 
about 20% by weight of (B), and from about 20 to about 30% by weight of 
(C). 
Preferred multi-polymer blends are those containing the following polymers 
as components (A), (B) and (C): (A) poly(methyl methacrylate) (PMMA)-(B) 
ethylene/vinyl alcohol-(C) poly(p-hydroxystyrene); (A) copolymer(80% 
methyl methacrylate/20% cyclohexyl methacrylate)-(B) ethylene/vinyl 
alcohol-(C) polycarbonate; (A) poly(N-methyldimethylglutarimide-(B) 
ethylene/vinyl alcohol-(C) poly(caprolactam); and (A) 
poly(N-methyldimethylglutarimide-(B) ethylene/vinyl alcohol-(C) 
poly(ethylene terephthalate). 
The poly(glutarimide) or poly(meth)acrylate may contain additives, such as 
lubricants, ultraviolet stabilizers, antioxidants, thermal stabilizers, 
and the like. It may also contain low levels of inorganic fillers and/or 
fibers, such as mica, glass fibers, and the like. 
The blend may be stabilized against interaction, e.g. transesterification 
and the like, between the alcohol groups of the poly(vinyl alcohol) 
polymer and the imide or ester groups of the glutarimide polymer; such 
stabilizers may be present in amounts from about 0.1% to about 2%. 
Preferred as stabilizers are phosphite or phosphinate esters, such as 
tris(nonylphenyl) phosphite at levels from about 0.1 to about 0.25 parts 
per 100 parts of total polymer. 
Other polymeric additives such as processing aids, fillers, lubricants, 
flame retardants, dyes, impact modifiers, surface altering agents, and the 
like may be present in the glutarimide or (meth)acrylate polymer blend. 
Such impact modifiers may include core/shell modifiers, such as those 
commonly called MBS modifiers, acrylate rubber//methacrylate outer stage, 
acrylate rubber//styrene/acrylonitrile outer stage, and the like. 
An especially useful blend of the present invention containing the impact 
modifiers is a blend of the first polymer, the second polymer, and 
impact-modified poly(vinyl chloride); this blend is tough, and exhibits 
barrier properties improved over the impact-modified PVC blend and a 
service temperature sufficient for hot-fill applications. 
Because the glutarimide polymers are relatively resistant to gas 
permeation, addition of other polymers, either as blends into the matrix 
or as impact modifiers, may lower the resistance to oxygen and moisture, 
and more of the other polymer containing vinyl alcohol mers may be 
required to achieve the desired balance of barrier and other properties. 
Without wishing to be bound by theory, in the binary blends the polymer 
containing vinyl alcohol mers may be dispersed in relatively fine 
particles, in laminar form, or even in such a fine dispersion that the 
blend acts like a compatible mixture, i.e., it exhibits a single 
glass-transition temperature. In many of the examples below, the 
dispersion of the ethylene/vinyl alcohol copolymer in the glutarimide 
continuous phase results in a fine and relatively uniform dispersion of 
the polymer with vinyl alcohol mers, with particle size averaging below 
50-100 nm, which is difficult to distinguish from a miscible blend. There 
is little or no laminar structure noted. In other examples, ethylene/vinyl 
alcohol polymer of higher ethylene content (44% versus 32%) produces a 
laminar structure in the glutarimide continuous phase; the barrier 
properties are comparable to those of the non-laminar blend. Thus, no 
specific morphology of the polymer causes the improvement in barrier 
properties, except that the polymer containing vinyl alcohol mers cannot 
be the continuous phase; when it is, the physical properties of the 
resulting blend are degraded, and the gas-barrier properties become 
sensitive to the presence of moisture. 
Some end uses require good clarity. This can be obtained by methods known 
in the art, i.e., by matching the refractive index of the matrix polymer 
or matrix polymers to that of the vinyl alcohol copolymer. This match must 
occur within the limits set forth herein for component-polymer levels, 
nature of the continuous phase, and compatibility of the polymers 
comprising the matrix blend. In other cases, particularly with 
multi-component blends containing reactive other polymers such as 
polyamides (nylons), clarity is observed where one skilled in the art 
would expect hazy or translucent blends. 
Many of the blends of the first polymer containing mers of (meth)acrylate 
or glutarimide with the second polymer containing at least 50 mol percent 
vinyl alcohol mers exhibit surprisingly good gas-barrier properties when 
compared with the barrier properties of the first polymer alone, or when 
compared with the expected improvement in barrier properties that should 
result from incorporating a relatively small amount of the polymer 
containing the vinyl alcohol mers. The improvement in gas-barrier 
properties of the first polymer is not a linear function of the amount of 
the second, vinyl-alcohol-containing polymer added, but instead increases 
sharply with the addition of only a small amount of second polymer, and 
shows little additional improvement at levels of second polymer beyond 40% 
by weight. As little as 10% by weight, and preferably from about 10 to 
about 40% by weight, of second polymer blended with the first polymer may 
produce a blend having oxygen permeability reduced by approximately an 
order of magnitude or more when compared to those of the first polymer 
alone. 
In the data reported herein, the theoretical or calculated permeability is 
based on what is essentially an averaging effect. This is the expected 
behavior for compatible or well-dispersed mixtures, and is represented by 
a straight-line plot of the natural logarithm of permeability versus 
concentration of the blend components. Where the dispersion is poor, 
another response to varying the concentration of the polymer having better 
barrier properties may occur: the S-shaped curve. In this case the barrier 
properties remain essentially those of the poorer barrier continuous phase 
as the concentration of the second phase is increased, until a 
concentration of the second phase is reached where phase inversion occurs, 
and the second phase undergoes a transition to the continuous phase as the 
poorer barrier polymer becomes the discontinuous phase. Through that 
transition, the barrier properties rapidly improve until they are 
essentially those of the second polymer, which has now become the 
continuous phase. Although the specific polymer combinations of the 
present invention exhibit essentially an S-shaped curve as the blend 
composition is varied, the marked improvement in barrier properties occurs 
in the absence of phase inversion, and at an unexpectedly low level of the 
second (good) barrier component. 
Blending conditions are not thought to be critical, so long as temperatures 
which cause significant loss of hydroxyl functionality from the vinyl 
alcohol mers, through either intra- or intermolecular reactions, are 
avoided. A reasonable range of processing temperatures is from about 
200.degree. C. to about 260.degree. C.; below this range the mixture is 
highly viscous and thus difficult to process, while above this range the 
polymer tends to thermally degrade at an excessive rate, and discoloration 
or bubbles may occur in the polymer if it is held at temperatures above 
this range for extended periods. A temperature range of from about 
230.degree. to about 240.degree. C. is preferred for the polyglutarimides. 
The polymers may be admixed and blended in a number of ways known to the 
polymer processing art. The polymers, along with any desired adjuvants 
and/or other polymers to be combined, may be mixed on a heated mill roll 
or other compounding equipment, and the mixture cooled, granulated and 
extruded into film. The polymers may be admixed in extruders, such as 
single-screw or double-screw extruders, compounded and extruded into 
pellets which may be then re-fabricated. The extruder may also be used to 
extrude the blend as pipe, sheet, film, or profile. Pelletized or 
granulated polymer may be injection or compression molded into sheet, 
film, or shaped articles. 
Through mixing and dispersion of the additive polymer is important, but 
otherwise processing conditions are similar to those of the unmodified 
matrix polymer and may be readily determined by appropriate 
experimentation and adjustment of processing conditions by one familiar 
with processing of the unmodified polymers. 
Films or sheets may be uniaxially or biaxially oriented either during 
extrusion or after such processing, by reheating and stretching. 
The polymer granules may be injection molded or extruded into appropriate 
parisons which are then treated by conventional molding and blowing 
techniques into bottles or other containers, which containers may be 
stretch oriented uniaxially or biaxially, or may be left unoriented. It is 
known in the art for such containers to have closures that allow them to 
be sealed or capped. 
Film or sheet may be treated with additives after forming, such as 
appropriate heat-seal adhesives, coatings for ink adhesions, printing, 
labels, and the like. 
Films or sheets of the blends of the present invention may be utilized in 
co-laminar structures, such as multilayered films, co-extrusion into 
bottles, and the like. In such operations, the blends have excellent 
adhesion to a variety of substrates, and separate adhesive layers, or "tie 
layers", are generally not required, although they may be used. The other 
polymer of the co-laminate may have specialized barrier properties, such 
as poly(vinylidene chloride) imparts. Preferred is a co-laminate which is 
tough or inexpensive, such as nylon, impact-modified nylon, poly(vinyl 
chloride), polycarbonate, poly(ethylene terephthalate), or a polyolefin 
such as polypropylene. Such co-laminar structure may involve more than one 
species of co-laminate and may also involve more than one layer of the 
blend polymer. The total number of layers is limited only by the 
capability of the equipment used to produce the multi-layer film or sheet. 
The films or sheets, as either monolithic or composite structures, and 
including articles formed from the films or sheets, may be biaxially 
oriented, uniaxially oriented or unoriented. 
The uses to which the gas-barrier polymers of the present invention may be 
put are many. Films or wrappings may be used in the packaging of many 
foodstuffs, such as meat, snacks, boil-in-the-bag items such as frozen 
vegetables, and the like. Containers suitable for the packaging of 
carbonated or oxygen-sensitive beverages, such as colas, ginger ale, fruit 
juice, and the like, may be prepared. Containers suitable for hot-fill or 
sterilization may be molded from suitable injection-molded or extruded 
parisons. 
Such containers or bottles may be used for packaging of condiments, 
ketchup, maple syrup, and the like. They may also be used for 
heat-sterilized containers, such as for intravenously administered fluids, 
serum vials, medical specimen vials and the like, and to package 
oxygen-sensitive chemicals. 
Other uses for transparent barrier compositions include protecting fragile 
artifacts, such as books and archaeological specimens, from oxidation 
while permitting them to be viewed readily. They may provide protective 
coatings for easily oxidized metals or oxygen-sensitive conductive 
polymers, as for example in solar-energy collection devices. They may also 
be used in devices where a specific concentration of gases must be 
maintained, such as so-called high-temperature metal oxide 
superconductors, which must be maintained in an oxidizing atmosphere, and 
controlled-atmosphere chambers used for handling sensitive chemical and 
biological materials, i.e. "dry boxes" and the like. 
The following examples are intended to illustrate the present invention and 
not to limit it except as it is limited by the claims. All percentages are 
by weight unless otherwise specified and all reagents are of good 
commercial quality unless otherwise specified. 
The resins used in the following examples are described below: 
Polyglutarimide as used in the following examples refers to polymers made 
by reacting poly(alkyl methacrylate) homo- or copolymers with amines or 
ammonia at elevated temperatures in a devolatilizing extruder. 
Poly(N-methylglutarimide) (PMG) refers to a commercial polymer made from 
poly(methyl methacrylate) and methyl amine. Acid-content-reduced 
poly(N-methylglutarimide) refers to a similar polymer further reacted with 
agents that eliminate acid and/or anhydride groups, as for example 
dimethyl carbonate, as taught in U.S. Pat. No. 4,727,117. In both cases, 
the Vicat softening temperature was related to the degree of imidization. 
Poly(methyl methacrylate) (PMMA) in these examples refers to polymers with 
a preponderance of methyl methacrylate mers, and particularly those with 
greater than 85% methyl methacrylate mers, with the other mers being lower 
alkyl esters of acrylic or methacrylic acid. PMMA homopolymer refers to a 
polymer with mers at least about 99% methyl methacrylate. Such polymers 
are made by free-radical polymerization in a continuous stirred tank 
reactor to a range of from about 30 to about 65% conversion at 
temperatures from about 120.degree. to about 200.degree. C., usually 
contain a mercaptan chain transfer agent, are separated from residual 
monomer in a devolatilizing extruder, extruded through a die and the 
extruded strands cut into pellets. Such polymers are the starting 
materials for the imidization reactions with ammonia or lower alkyl 
amines. It should be noted that the process for preparing the PMMA is not 
restricted to the continuous process described above; well-known methods 
such as bulk casting, suspension polymerization, and emulsion 
polymerization may also be used. In the multi-polymer blends, the 
polycarbonate was a commercial bis-phenol A polycarbonate obtained from 
Mobay Chemical Company, having a melt flow rate of 55-60 grams/10 minutes 
at 300.degree. C., measured according to ASTM Method D 1238. The 
poly(.rho.-hydroxystyrene), of 32,000 weight-average molecular weight, was 
purchased from Hoechst-Celanese, and was reported to have a barrier value 
against oxygen of 7.88 cm.sup.3.mm/(m.sup.2.atm.day). 
They poly(ethylene-vinyl alcohol) copolymers and the poly(vinyl alcohol) 
polymers were commercially available; both are believed to be prepared by 
the hydrolysis or saponification of the corresponding vinyl acetate co- or 
homopolymers. For the copolymers used, the molar percentage of ethylene in 
the copolymer and the melt index, as a correlation with weight-average 
molecular weight, are given in Table I, below. 
TABLE I 
______________________________________ 
Vinyl Alcohol Homo- and Copolymers 
Desig- Mol % Melt 
nation 
Polymer Type Ethylene Index MW 
______________________________________ 
CoP-1 Ethylene-vinyl alcohol 
32 1.3 -- 
CoP-2 Ethylene-vinyl alcohol 
44 5.5 -- 
CoP-3 Ethylene-vinyl alcohol 
27 -- -- 
CoP-4 Ethylene-vinyl alcohol 
38 3.5 -- 
HP-1 Poly(vinyl alcohol) 
-- -- 14000 
HP-2 Poly(vinyl alcohol) 
-- -- 85000 
HP-3 Poly(vinyl alcohol) 
-- -- 115000 
HP-4 Poly(vinyl alcohol) 
-- -- -- 
______________________________________ 
Melt index was in grams/10 minutes, measured at 190.degree. C. for CoP-1 
and CoP-2 and 210.degree. C. for CoP-4. 
The commercial designations are: CoP-1: Eval F-101A; CoP-2=Eval E 105A; 
CoP-3=Eval L (all supplied by Evalco); CoP-4=Soarnol ET, supplied by 
Nichimen America, Inc. New York, N.Y. (U.S. agents for Nippon Gohsei of 
Japan); HP-1, HP-2, and HP-3 supplied by Polysciences Inc. Warrington, PA 
18976; HP-4=Hitech Polyvinyl alcohol containing an unspecified 
plasticizer, made according to U.S. Pat. No. 4,536,532, and supplied by 
Hitech Polymers, Inc., P. O. Box 30041, Cincinnati, Ohio 45230. 
Blending of polymers: Polymer blends were prepared by tumble-blending 
pellets, usually with addition of a small amount of thermal stabilizer 
(0.25 wt. % tris(nonylphenyl phosphite) based on total resin content). The 
pellets were fed to a twin-screw, counter-rotating, intermeshing extruder, 
length 870 mm, equipped with a vacuum vent, a single-hole strand die of 
approximately 6 mm. diameter, a water bath for cooling the extruded 
strand, and a strand pelletizer. The feed zone was set at 230.degree. C., 
and the barrel and die zones at 235.degree. C. The melt temperature was 
between 226.degree. and 238.degree. C.; a screw speed of 100 rpm was 
employed. 
Alternatively, for smaller samples, blends were prepared from blends of 
polymer powders and granulated pellets or bulk castings. They were milled 
on a two-roll electric mill for three minutes at 205.degree.-215.degree. 
C., then removed from the mill rolls, cooled, granulated and compression 
molded using a Carver press. The samples were molded at 138 megapascals 
(MPa) and 215.degree. C. into 127-mm-square plaques 0.13 mm thick. 
Preparation of films: A single-screw extruder, 25.4 mm in diameter, 24/1 
length/diameter ratio was equipped with a two-stage vacuum vent, a 152.4 
mm "coat-hanger" adjustable-thickness film die, a three-roll, heated film 
stack immediately adjacent to the die lips for receiving the film on 
extrusion, and a film puller and film wind-up apparatus. The puller speed 
was set to avoid any drawdown of the film. The extruder was operated at 75 
rpm; melt temperatures were usually 232.degree. to 237.degree. C., but may 
be adjusted depending on recommendations from the resin supplier to 
achieve acceptable extrusion rates. The roll temperatures of the stack 
were: top and middle: 132.degree. C., bottom 100.degree. C. Film of 
thickness 76 to 635 .mu.m were prepared by this method. 
Injection Molding: Blended pellets were molded in an injection-molding 
apparatus equipped with a heated, ASTM family mold. Injection pressures 
were 5.17 to 7.58 megaPascals (MPA), with back pressure of 0.69 MPa; the 
melt temperature was 232.degree. to 260.degree. C., depending upon the 
viscosity of the polymer melt. The mold temperature was 110.degree. C. 
Morphology: Polymeric blends were sectioned by microtoming at room 
temperature to sections about 100 nm thick, and stained with ruthenium 
tetroxide by the method of Trent et al., Macromolecules, 16, 589 (1983). 
Exposure to vapors from a 0.5% aqueous solution of RuO.sub.4 was about one 
hour at room temperature. Transmission electron microscopy at a 
magnification of up to 25000X was carried out on a Zeiss EM-10 instrument. 
Oxygen permeability values: Permeability was tested on a Mocon Ox-Tran 1000 
unit, manufactured by Modern Controls, Minneapolis, Minn. Films of 
measured dimensions were mounted in the unit, equilibrated with nitrogen 
to determine any leakage factor or edge effect, and then exposed to pure 
oxygen test gas until the carrier gas on the opposite side of the film 
reached equilibrium. Oxygen was detected by a nickel-cadminum fuel cell 
known as a Coulox Detector. The unit was equipped to record the oxygen 
content which was calculated in units of cm.sup.3.mil/100 
in.sup.2.atm.day; these units were converted to 
cm.sup.3.mm/m.sup.2.atm.day by multiplying by 0.3937. The resulting values 
were compared with values measured or reported for the single component 
(non-blend) film. Measurements were at 23.degree. C. and 0% relative 
humidity unless otherwise noted. 
EXAMPLE 1 
This example illustrates preparation of a blend of a poly(glutarimide) and 
an ethylene-vinyl alcohol copolymer. The values for the ethylene-vinyl 
alcohol polymer were from the manufacturer's literature, and were 
conducted on the dry polymer molding or film unless otherwise noted. Film 
thickness was approximately 0.178 mm. The properties of the resulting 
blend are shown in Table II below. 
TABLE II 
______________________________________ 
Properties of a Polyglutarimide-Ethylene-Vinyl Alcohol Blend 
Polymer or Blend 
Physical Glutarimide containing 
Property Glutarimide.sup.1 
CoP-1.sup.2 
10 wt. percent CoP-1 
______________________________________ 
O.sub.2 Perm., 
1.0 &gt;0.002 0.055 
0% RH 
O.sub.2 Perm., 
1.0 3.7 0.16 
100% RH 
Tensile 4595 3686 4134 
Modulus, MPa 
Glass temper- 
170.sup.3 65 169,69.sup.4 
ature, .degree.C. 
Visual clarity 
excellent poor good 
______________________________________ 
.sup.1 Nmethylglutarimide, no acid reduction treatment, Vicat 170.degree. 
C. 
.sup.2 see Table describing composition and MW of ethylenevinyl alcohol 
copolymers. 
.sup.3 from Vicat penetration or softening temperature 
.sup.4 two peaks, from differential scanning calorimetry 
EXAMPLES 2-6 
These examples illustrate the oxygen permeability of glutarimide blends 
with 10 to 25 weight percent of several polymers containing vinyl alcohol 
mers. Blends were prepared with the same glutarimide matrix as in Example 
1. Values were at 0% relative humidity. The oxygen permeability for the 
blends at the specified levels of polymers containing the vinyl alcohol 
mers are shown in Table III below. 
TABLE III 
______________________________________ 
Oxygen Permeability of Polyglutarimide Blends 
Level of Copolymer in Glutarimide 
Vinyl Alcohol of Example 1, wt. % 
Example 
(Co)polymer 0% 10% 15% 20% 25% 
______________________________________ 
1 CoP-1, Ex. 4.92 0.057 -- 0.083 -- 
2 CoP-4 -- &lt;0.3.sup.1 
-- &lt;0.002 
-- 
3 HP-1 -- 1.0 -- &lt;0.002 
4 HP-2 -- 0.91 -- &lt;0.002 
-- 
5 HP-3 -- 1.06 -- 0.71 -- 
6a HP-4, Lot 1 -- 0.055 -- 0.083 -- 
6b HP-4, Lot 2 -- 0.71 0.79 -- 0.13 
______________________________________ 
.sup.1 In separate measurement, &lt;0.005 was value. 
EXAMPLE 7 
This example illustrates rapid decrease of oxygen permeability at 
increasing but still low levels of an ethylene-vinyl alcohol copolymer. 
The polymers and processing were that of Example 1. The predicted values 
were those read from a line drawn on semi-log paper between the 0 and 100 
CoP-1 levels. Film thicknesses were about 0.177 mm. The observed and 
predicted values for oxygen permeability of the blends are shown in Table 
IV below. 
TABLE IV 
______________________________________ 
Oxygen Permeability of Polyglutarimide-Ethylene-Vinyl 
Alcohol Blends 
% CoP-1 Predicted 
Found 
______________________________________ 
0 -- 1.22 
1 1.18 0.81 
2.9 1.10 0.88 
6.5 0.97 0.81 
9.1 0.88 0.34 
11.1 0.82 0.24 
12.6 0.78 0.13 
15 0.71 0.078 
100 -- 0.033 
______________________________________ 
The onset of substantial lessening of oxygen permeability in the present 
system was seen at about 9 wt. % of the CoP-1 additive, but values below 
the theoretical were seen at lower concentrations in the blend. 
Examination of the blends with above 9.1% CoP-1 showed little evidence of 
a laminar morphology for the dispersed CoP-1 phase. 
EXAMPLE 8 
This example illustrates rapid decrease of oxygen permeability at 
increasing but still low levels of a second ethylene-vinyl alcohol 
copolymer (CoP-3, containing 27 mol-% ethylene). The PMG was that of 
Example 1. The predicted values were those read from a line drawn on 
semi-log paper between the 0 and 100 CoP-3 levels. Film thicknesses were 
about 0.177 mm. The predicted and observed values for oxygen permeability 
of the blends are shown in Table V below. 
TABLE V 
______________________________________ 
Oxygen Permeability of Polyglutarimide-Ethylene-Vinyl 
Alcohol Blends 
% CoP-3 Predicted 
Found 
______________________________________ 
0 -- 1.22 
3 1.15 1.32 
6.5 0.79 1.15 
9 0.69 0.67* 
11 0.61 0.17* 
15 0.45 0.07 
17.5 0.38 0.026 
20 0.32 0.086 
23.6 0.25 0.0016 
100 -- 0.0016 
______________________________________ 
*From a separate series of experiments. 
EXAMPLE 9 
This example illustrates rapid decrease of oxygen permeability at 
increasing but still low levels of a third ethylene-vinyl alcohol 
copolymer (CoP-2, containing 44 mol-% ethylene). The PMG was that of 
Example 1. The predicted values were those read from a line drawn on 
semi-log paper between the 0 and 100 CoP-2 levels. Film thicknesses were 
about 0.177 mm. The predicted and observed values for oxygen permeability 
of the blends are shown in Table VI below. 
TABLE VI 
______________________________________ 
Oxygen Permeability of Polyglutarimide-Ethylene-Vinyl 
Alcohol Blends 
Oxygen Permeability 
% CoP-2 Predicted 
Found 
______________________________________ 
0 -- 1.22 
6 0.96 1.24 
9 0.84 0.70 
12 0.74 0.58 
13.4 0.70 0.43 
14.3 0.68 0.54 
15 0.66 0.10 
20 0.54 0.20 
25 0.44 0.002 
27.3 0.40 0.0015 
35 0.29 0.18 
40 0.24 0.24 
100 -- 0.001 
______________________________________ 
Microscopic examination of the blend containing 20% of the CoP-2 additive 
showed a laminar morphology for the dispersed CoP-1 phase. 
EXAMPLES 10-26 
These examples show the effect of relative humidity on blends of a 
poly(vinyl alcohol) homopolymer with various glutarimide matrices. The 
poly(vinyl alcohol) was that used in Example 1 (HP-4). The 
polyglutarimides were imidized in a devolatilizing extruder to degrees of 
imidization measured by the Vicat softening temperature of the resulting 
resin. Portions of these polymers were then reduced in acid content by 
treatment by the method of Hallden-Abberton et al. The polymers used in 
the examples are shown in Table VII below. 
TABLE VII 
______________________________________ 
Polymers Used in Relative Humidity Effects Study 
Poly(glutarimide) Vicat softening 
Example 
Source Acid-reduced? 
temperature, .degree.C. 
______________________________________ 
10 PMG N 170 
(from Example 1) 
11 PMG N 150 
12 PMG-T Y (Ex. 10) 160 
13 PMG-T Y (Ex. 11) 145 
______________________________________ 
Blends of these polymers were then made as in previous examples, with the 
poly(vinyl alcohol) at 10 and 20% use levels, and oxygen permeability 
measured at 0 and 100% relative humidities on films of similar 
thicknesses. The results of these measurements are shown in Table VIII 
below. 
TABLE VIII 
______________________________________ 
Effects of Relative Humidity on Oxygen Permeability of Blends 
Source of Wt. % Relative 
Oxygen 
Example 
Glutarimide 
PVOH(HP-4) Humidity 
Permeability 
______________________________________ 
1 Ex. 10 -- 0 0.98 
1 Ex. 10 -- 100 0.98 
14 Ex. 10 10 0 0.71 
15 Ex. 10 10 100 1.3 
16 Ex. 11 -- 0 1.2 
17 Ex. 11 10 0 1.2 
18 Ex. 11 10 100 1.5 
19 Ex. 11 20 0 1.1 
20 Ex. 12 10 0 1.2 
21 Ex. 12 10 100 1.9 
22 Ex. 12 20 0 0.002 
23 Ex. 13 -- 0 2.2 
24 Ex. 13 10 0 1.5 
25 Ex. 13 10 100 2.2 
26 Ex. 13 20 0 0.94 
______________________________________ 
These data show that a) high relative humidity is deleterious to 
permeability behavior, even at the relatively low levels of poly(vinyl 
alcohol) homopolymer employed, and b) 10% of poly(vinyl alcohol) additive 
is not enough to produce a drastic decrease in the permeability value. 
EXAMPLES 27-36 
These examples illustrate that substantial improvements in barrier 
performance can be achieved by blending relatively low levels of an 
ethylene-vinyl alcohol copolymer with an acid-reduced 
poly-N-methylglutarimide. The polyglutarimide was that of Example 12 
except for one example where a polymer of lower imide content (Ex. 13) was 
used; the vinyl alcohol copolymer was CoP-1. The oxygen permeability of 
the blends is shown in Table IX below. 
TABLE IX 
______________________________________ 
Oxygen Permeability of Blends of Acid-Reduced Polyglutarimide 
with Ethylene-Vinyl Alcohol Polymer 
Source of Wt. % Relative 
Oxygen 
Example Glutarimide 
CoP-1 Humidity 
Permeability 
______________________________________ 
27 Ex. 12 0 0 2.42 
28 Ex. 12 3 0 3.40 
29 Ex. 12 6 0 2.15 
30 Ex. 12 9 0 0.721 
31 Ex. 12 10 0 1.2 
32 Ex. 13 11.1 0 0.33 
33 Ex. 12 12 0 0.131* 
34 Ex. 12 15 0 0.0004 
35 Ex. 12 20 0 0.0004 
36 Ex. 12 25 0 0.079* 
______________________________________ 
*sample pelletized poorly and film may not have been uniform. 
EXAMPLE 37 
This example illustrates that blends of non-imidized poly(methyl 
methacrylate) will also exhibit unexpectedly good barrier properties when 
blended with an ethylene-vinyl alcohol copolymer. The polymer used is a 
poly(methyl methacrylate) homopolymer of molecular weight ca. 150,000. The 
unmodified PMMA has an oxygen permeability value of 3.9 
cm.sup.3.mm/m.sup.2.atm.day; the value for the blend with 20% CoP-1 was 
0.004. The blend had excellent contact clarity and was only slightly hazy. 
EXAMPLES 38-40 
These examples illustrate that a glutarimide prepared from ammonia does not 
exhibit the improvement in barrier properties at low levels of blending 
with a ethylene-vinyl alcohol; copolymer. The ammonia imide had a Vicat 
temperature of 205.degree. C., was&gt;90% imidized, and about 48% percent of 
the imide groups were N-methylimide (during imidization with ammonia, 
monomethylamine is formed, which then competes for the sites of 
imidization). The samples at 5 and 10% ethylene-vinyl alcohol polymer were 
hazy; the sample at 20% could not be processed, possibly due to chemical 
interactions leading to crosslinking. Results of these tests are shown in 
Table X, below. 
TABLE X 
______________________________________ 
Oxygen Permeability of Ammonia Polyglutarimides Blended 
with Poly(Ethylene-Vinyl Alcohol) 
Glutarimide 
% Relative 
Oxygen 
Example Glutarimide 
CoP-1 Humidity 
Permeability 
______________________________________ 
38 Ammonia -- 0 .about.0.4 
39 Ammonia 5 0 1.3 
40 Ammonia 10 0 1.8 
______________________________________ 
EXAMPLE 41 
This example illustrates that a styrene copolymer containing imide units 
does not exhibit outstanding barrier properties. A commercial 
styrene-maleic anhydride copolymer containing about 20% anhydride by 
weight was treated with methylamine to yield the N-methylsuccinimide 
functionality. The permeability value for the polymer was greater than 
200. Blending with 20% CoP-1 did not substantially decrease the 
permeability value. 
EXAMPLE 42 
This example demonstrates that the blends of glutarimide polymer and 
ethylene-vinyl alcohol polymer may be further combined with poly(vinyl 
chloride) and a methacrylate-butadiene-styrene impact modifier to produce 
a blend with good barrier performance and improved service temperature. 
Poly(vinyl chloride) formulations were prepared as follows: 
Poly(vinyl chloride), K=69:100 parts 
Organotin stabilizer: 1.0 phr 
Polyglutarimide, (Ex. 11): 0 or 40 phr 
Ethylene-vinyl alcohol: 0 or 4.4 phr copolymer, (CoP-1) 
MBS modifier: 0 or 24 phr 
The materials were intensively blended while dry, milled for 5 minutes on a 
two-mill roll at 190.degree. C., and the resulting polymer blend pressed 
into a film which was 0.2 mm thick. Results of oxygen permeability tests 
on these materials are shown in Table XI, below. 
TABLE XI 
______________________________________ 
Blends of Polyglutarimide-Ethylene Vinyl Alcohol 
with Poly(Vinyl Chloride) and MBS 
Glutarimide, 
phr CoP-1, phr MBS, phr Oxygen Permeability 
______________________________________ 
0 0 0 3.1 
40 0 0 3.7 
40 0 24 8.23 
40 4.4 0 2.5 
40 4.4 24 3.5 
______________________________________ 
EXAMPLES 43-52 
These examples illustrate that copolymers of methyl methacrylate with 
acrylic monomers bearing functional groups, which are expected to improve 
compatibility with the vinyl alcohol moieties of an ethylene-vinyl alcohol 
copolymer, exhibit an unexpected improvement in barrier properties. All 
blends contain 80% methacrylic copolymer and 20% of the ethylene-vinyl 
alcohol designated CoP-1. Controls with no CoP-1 are noted. The copolymers 
are prepared by emulsion polymerization, as follows: 
Five monomer mixtures were prepared, having respective methyl 
methacrylate:hydroxyethyl methacrylate ratios of 100:0, 95:5, 90:10, 85:15 
and 80:20. Each mixture contained 1320 parts of methyl 
methacrylate:hydroxyethyl methacrylate monomer, 3.96 parts n-dodecyl 
mercaptan, 778.24 parts water and 19.8 parts 10% aqueous sodium 
dodecylbenzene sulfonate solution (a total of 2122 parts). 
Each monomer mixture was polymerized according to the following procedure. 
To an appropriate glass vessel equipped with stirrer, heater, a reflux 
condenser, and nitrogen sparge tube, was added 1992 parts of deionized 
water, 59.4 parts of a 10% aqueous solution of sodium dodecylbenzene 
sulfonate, and 1 part of sodium carbonate. The mixture was sparged for one 
hour with nitrogen while heating to 70.degree. C. Ten percent of the 
monomer mixture (212.2 parts) was added at 70.degree. C. and the mixture 
was heated to 85.degree. C. Then 14.89 parts of a solution of sodium 
persulfate (2.24 parts) in 146.63 parts of deionized water was added. The 
reaction was monitored until a color change and exotherm were observed, 
signalling the onset of polymerization. Sixty minutes after onset, gradual 
addition of the remainder of the monomer mix was begun and continued over 
three hours. During that time, the remainder of the initiator solution was 
added in 14.89-part portions every 15 minutes. At the completion of the 
monomer addition the mixture was held at 85.degree. C. for one hour. The 
mixture was then cooled, filtered, and the polymer isolated by 
freeze-drying. 
Blends with and without the ethylene-vinyl alcohol copolymer were prepared 
for testing by milling and compression molding films, and the oxygen 
permeability was determined as described above. Table XII shows the 
results for these films. 
TABLE XII 
__________________________________________________________________________ 
Oxygen Permeability-Copolymers and Binary Blends of MMA/HEMA//CoP-1 
% Composition 
Calculated 
Observed 
Example 
Polymer/Blend (w//w) Perm..sup.1 
Perm..sup.1 
__________________________________________________________________________ 
43 (MMA/HEMA = 100/0) 
100//0 2.96 
44 (MMA/HEMA = 95/5) 
100//0 2.90 
45 (MMA/HEMA = 90/10) 
100//0 2.93 
46 (MMA/HEMA = 85/15) 
100//0 2.67 
47 (MMA/HEMA = 80/20) 
100//0 2.15 
48 (MMA/HEMA = 100/0)// CoP-1 
80//20 8.27.sup.2 
49 (MMA/HEMA = 95/5)// CoP-1 
80//20 0.77 0.39 
50 (MMA/HEMA = 90/10)// CoP-1 
80//20 0.78 0.35 
51 (MMA/HEMA = 85/15)// CoP-1 
80//20 0.72 0.34 
52 (MMA/HEMA = 80/20)// CoP-1 
80//20 0.61 0.37 
__________________________________________________________________________ 
.sup.1 indicates units of cm.sup.3 .multidot. mm/m.sup.2 .multidot. atm 
.multidot. day 
.sup.2 This value is anomalously high; compare with Example 37. In no 
other instance has a value for the methacrylate polymer blend with a viny 
alcohol polymer given a higher value for oxygen permeability than the 
unmodified control. 
EXAMPLES 53-65 
These examples illustrate that copolymers of cyclohexyl methacrylate with 
methyl methacrylate may be blended with another resin plus the 
ethylene-vinyl alcohol polymer identified herein as CoP-1, to form tough 
blends having light transmission properties ranging from translucent to 
transparent. 
Samples of the methyl methacrylate/cyclohexyl methacrylate copolymer were 
prepared as follows: Bags of poly(vinyl alcohol) film were prepared with 
tightly sealed edges, except for an opening to allow addition of liquids. 
A monomer mixture of methyl methacrylate (MMA)/cyclohexyl methacrylate 
(CHMA) was prepared from 2700 parts MMA and 800 parts of CHMA. A separate 
initiator solution was prepared from 2200 parts MMA, 2.464 parts 
azobis(isobutyronitrile), 4.928 parts t-butyl peroxyacetate, and 70.4 
parts n-dodecyl mercaptan. To the MMA/CHMA mixture was added 517.7 parts 
of the initiator solution. The resulting monomer-initiator mixture was 
degassed by sparging with nitrogen and transferred to a poly(vinyl 
alcohol) bag. 
The bag was degassed under mild vacuum. The bag was then heated to 
45.degree. C. and held at that temperature for at least 24 hours, then 
slowly heated to 120.degree. C. and held there for six hours. The 
poly(vinyl alcohol)-film bag was removed from the resulting polymer, which 
was then washed with water, dried, and granulated. 
In the following blends of Table XIII, the acrylic copolymer was blended 
with the polycarbonate (a commercial molding grade of bis(phenol-A) 
polycarbonate) at various ratios, then that blend was blended further with 
the ethylene-vinyl alcohol copolymer. 
The blends were prepared as described above for "Blending of polymers." 
Extrusion or the alternative milling procedure were used depending upon 
the amount of polymer made. 
TABLE XIII 
__________________________________________________________________________ 
% Composition 
Calculated 
Observed 
Example 
Polymer//Blend (w//w) Perm.* 
Perm.* 
__________________________________________________________________________ 
53 (MMA/CHMA = 80/20) 
100//0 9.88 
54 (MMA/CHMA = 80/20)//PC 
75//25 18.04 15.46 
55 (MMA/CHMA = 80/20)//PC 
50//50 32.84 28.99 
56 (MMA/CHMA = 80/20)//CoP-1 
76//24 1.51 
57 (MMA/CHMA = 80/20)//CoP-1 
54//46 0.27 0.03 
58 (MMA/CHMA = 80/20)//CoP-1 
68//32 0.81 0.51 
59 (MMA/CHMA = 80/20)//CoP-1 
44//56 0.12 0.03 
60 (MMA/CHMA = 80/20)//PC- 
81//19 3.61 0.26 
{75//50}//CoP-1 
61 (MMA/CHMA = 80/20)//PC- 
61//39 0.97 0.23 
{50//50}//CoP-1 
62 PC//CoP-1 28//72 0.07 0.03 
63 PC//CoP-1 44//56 0.33 0.04 
64 PC 100//0 109.66 
65 CoP-1 100//0 0.004 
__________________________________________________________________________ 
*indicates units of cm.sup.3 .multidot. mm/m.sup.2 .multidot. atm 
.multidot. day 
EXAMPLES 66-72 
The following examples illustrate that when the level of the third polymer, 
whose barrier properties are not decreased dramatically by the vinyl 
alcohol polymer blends, is raised above a critical level of about 25% of 
the barrier polymer, the advantage of surprising barrier properties of the 
ternary blend with an acrylic polymer is lost. 
TABLE XIV 
__________________________________________________________________________ 
Oxygen Permeability of Transparent Ternary Blends of 
(MMA/CHMA = 80//20)/PC//CoP-1 
% Composition 
Calculated 
Observed 
Example 
Polymer/Blend (w/w) Perm.* 
Perm.* 
__________________________________________________________________________ 
66 (MMA/CHMA = 80/20)//PC- 
80//20 5.41 19.6 
50/50)//CoP-1 
67 (MMA/CHMA = 80/20)//PC- 
80//20 5.10 20.1 
53/47)//CoP-1 
68 (MMA/CHMA = 80/20)//PC- 
80//20 4.91 16.3 
55/45)//CoP-1 
69 (MMA/CHMA = 80/20)//PC- 
80//20 4.73 18.0 
57/43)//CoP-1 
70 (MMA/CHMA = 80/20)//PC- 
80//20 4.46 15.1 
60/40)//CoP-1 
71 (MMA/CHMA = 80/20)//PC- 
80//20 4.21 15.7 
63/47)//CoP-1 
72 (MMA/CHMA = 80/20)//PC- 
80//20 4.05 16.9 
65/35)//CoP-1 
__________________________________________________________________________ 
*indicates units of cm.sup.3 .multidot. mm/m.sup.2 .multidot. atm 
.multidot. day. 
EXAMPLES 73-76 
The following examples illustrate that a blend of 
poly(.rho.-hydroxystyrene), which is compatible with methyl methacrylate, 
and which has barrier properties somewhat similar to those of poly(methyl 
methacrylate), may be used in conjunction with an ethylene-vinyl alcohol 
copolymer to produce the unexpected improvement in barrier properties. 
Poly(.rho.-hydroxystyrene) of 32,000 weight-average molecular weight was 
purchased from HoechstCelanese. The barrier value for this material is 
reported to be 7.88 cm.mm/m.sup.2.atm.day. 
Three-component blends were prepared as described above for "Blending of 
polymers." Extrusion or the alternative milling procedure were used 
depending upon the amount of polymer made. The oxygen permeability of the 
samples was determined, and is shown in Table XV. The reduction in 
permeability over expected values is not discernible at low percentages of 
the ethylene-vinyl alcohol polymer, but it is quite apparent that 
permeability has been substantially decreased when the level of that 
copolymer in the blend reaches about 20%. 
TABLE XV 
__________________________________________________________________________ 
Oxygen Permeability of Ternary Blends of PMMA// Poly(p- 
Hydroxystyrene (PpHS)//Ethylene-Vinyl Alcohol (CoP-1) 
% Composition 
Calculated 
Observed 
Example 
Polymer/Blend 
(w/w) Perm.* 
Perm.* 
__________________________________________________________________________ 
73 PMMA//PpHS//CoP-1 
89.9/6.7/3.4 
5.54 6.46 
74 PMMA//PpHS//CoP-1 
87.0/8.7/4.3 
5.19 7.30 
75 PMMA//PpHS//CoP-1 
83.4/8.3/8.3 
3.84 4.37 
76 PMMA//PpHS//CoP-1 
54.0/26.0/20.0 
1.63 0.120 
__________________________________________________________________________ 
EXAMPLES 77-88 
These examples illustrate blends of the first copolymer containing mers of 
heterocyclic monomers. Copolymers of these examples were prepared in 
emulsion using a polymerization procedure similar to that of Example 43. 
N-vinylpyrrolidone (N-VP), 4-vinylpyridine (4-VP) and .rho.-acetoxystyrene 
are commercially available monomers. The polymer containing units of 
p-hydroxystyrene was prepared as follows: In a flask fitted with a reflux 
condenser and stirrer, 100 g of p-acetoxystyrene copolymer with methyl 
methacrylate was dissolved in 1000 ml tetrahydrofuran. To this solution 
was added 25 g sodium hydroxide dissolved in 100 ml water. The mixture was 
refluxed for two hours, then cooled to 50.degree. C.; 500 ml water was 
then added, followed by glacial acetic acid unitl the flask contents were 
slightly acidic. Water (500-1000 ml) was added to fully precipitate the 
polymer, which was then filtered and dried under vacuum and blended as in 
Example 43 with various polymers containing vinyl alcohol units. CoP-5 and 
CoP-6 are copolymers which are primarily vinyl alcohol having long-chain 
(up to C.sub.20) alkenoxy methacrylate ester mers grafted onto the 
polymer, and were obtained from Air Products Company. CoP-5 has a melt 
index of 4.5 g/10 minutes, a glass transition temperature (T.sub.g) of 
46.degree. C., and a melt viscosity of 9408 poise at 19.degree. C. CoP-6 
has a melt index of 14 g/10 minutes, a T.sub.g of 24.degree. C., and a 
melt viscosity of 2970 at 195.degree. C. The melt indices are measured at 
230.degree. C. and 2160 g, and the melt viscosities are at zero shear. 
Most of the polymer blends shown in Table XVI show better resistance to 
oxygen permeability than predicted by plotting either a linear or an 
S-shaped curve of the natural logarithm of permeability versus polymer 
composition, based on the barrier properties of the individual components. 
TABLE XVI 
__________________________________________________________________________ 
Oxygen Permeability of Binary Blends of MMA Copolymers 
with Polar Monomers //Ethylene-Vinyl Alcohol Copolymer 
% Composition 
Calculated 
Observed 
Example 
Polymer/Blend (w/w) Perm.* 
Perm.* 
__________________________________________________________________________ 
77 (MMA/4VP = 90/10)//CoP-1 
80//20 2.27 0.131 
78 (MMA/4VP = 80/20)//CoP-1 
80//20 2.27 0.43 
79 (MMA/NVP = 75/25) 
100//0 3.45 
80 (MMA/NVP = 75/25)//CoP-1 
80//20 0.89 0.019 
81 (MMA/NVP = 75/25)//CoP-1 
75//25 0.63 0.013 
82 (MMA/NVP = 75/25)//CoP-5 
80//20 0.89 0.057 
83 (MMA/NVP = 75/25)//CoP-5 
75//25 0.63 0.056 
84 (MMA/NVP = 75/25)//CoP-5 
66//34 0.34 0.004 
85 (MMA/NVP = 75/25)//CoP-6 
80//20 0.89 0.030 
86 (MMA/NVP = 75/25)//CoP-6 
75//25 0.63 0.033 
87 (MMA/NVP = 75/25)//PVOH 
80//20 0.64 1.819 
88 (MMA/NVP = 75/25)//PVOH 
75//25 0.64 2.226 
__________________________________________________________________________ 
*indicates units of cm.sup.3 .multidot. mm/m.sup.2 .multidot. atm 
.multidot. day. 
EXAMPLES 89-100 
In the following examples, blends were prepared from CoP-1, 
N-methyldimethylglutarimide of Vicat softening temperature 170.degree. C. 
and made without acid reduction treatment, and nylon 6 (poly(caprolactam)) 
manufactured by Allied -Signal Inc. as Capron 8202. Sodium hydroxide was 
added at a level of 500 parts per million parts of the total polymer blend 
to those blends indicated "NaOH - Yes" below. These polymers were blended 
in a 2.5-cm Killion extruder equipped with a barrier screw operating at 
100 rpm and a 4.8-mm die, and having the following temperature profile: 
feed zone--250.degree. C.; zone 2--300.degree. C.; zone 3--300.degree. C.; 
die 1--275.degree. C.; die 2--275.degree. C. Blended samples were 
compression molded into 100-mm square films for permeability testing. The 
blend compositions and testing results are shown in Table XVII below. Upon 
visual examination, all samples were transparent and free from haze. 
TABLE XVII 
__________________________________________________________________________ 
Imide-Poly(Vinyl-Alcohol)-Polyamide Blends 
Exam- 
Glutar- 
Nylon 
CoP-1 Film Thick- 
Permeability 
ple imide % 
6% % NaOH 
ness, .mu.m 
* Clarity 
__________________________________________________________________________ 
89 80.75 
5.0 14.25 
No 307 0.705 Haze-free 
90 80.75 
5.0 14.25 
No 279 0.669 Haze-free 
91 72.25 
15.0 
12.75 
No 376 0.657 Haze-free 
92 72.25 
15.0 
12.75 
No 269 0.677 Haze-free 
93 72.25 
15.0 
12.75 
Yes 315 0.516 Haze-free 
94 63.75 
25.0 
11.25 
No 345 0.508 Haze-free 
95 63.75 
25.0 
11.25 
No 295 0.748 Haze-free 
96 63.75 
25.0 
11.25 
Yes 340 0.776 Haze-free 
97 63.75 
25.0 
11.25 
Yes 325 0.929 Haze-free 
98 47.5 47.5 
5.0 Yes 246 1.14 Haze-free 
99 45.0 45.0 
10.0 
Yes 170 0.921 Haze-free 
100 42.5 42.5 
15.0 
Yes 216 0.638 Haze-free 
__________________________________________________________________________ 
*indicates units of cm.sup.3 .multidot. mm/m.sup.2 .multidot. atm 
.multidot. day. 
While the invention has been described with reference to specific examples 
and applications, other modifications and uses for the invention will be 
apparent to those skilled in the art without departing from the spirit and 
scope of the invention defined in the claims below.