Thermoplastic polyolefin resin composition and laminar articles having improved barrier properties prepared

Laminar articles having improved barrier properties to organic solvents and gases, fabricated directly from polyolefin and modified polyamide, are disclosed. The modified polyamide is a blend of 97-40 wt % polyamide and 3-60 wt % of compatabilizer which is a polyether ester amide block copolymer or a mixture of the block copolymer and alkylcarboxyl-substituted polyolefin.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to a polyolefin resin composition and the 
laminar articles prepared therefrom, which exhibits improved barrier 
properties to permeation of organic solvents and gases. 
2. Description of the Prior Art 
Polyolefins have been widly used in the manufacture of containers and 
packing materials for fluids. However, as they do not exhibit good barrier 
properties to permeation of organic solvents and gases, their uses are 
limited. 
U.S. Pat. Nos. 2,811,463, 3,862,284, 3,998,180, 4,081,574, 4,142,032, 
4,394,333 and 4,467,075, disclose that the barrier properties to the 
permeation of organic solvents and gases of a plastic film or container 
can be improved by surface treatment with fluorine and bromine gases. 
Japan Kokai Koho No. 55-80439 discoses a method of treating the surface of 
polyolefin articles with fluorocarbon compounds by plasma to improve the 
barrier properties to the permeation of gasoline and hydrocarbon vapors. 
U.S. Pat. No. 4,182,457 and Japan Kokai Koho Nos. 59-103726 and 59-103727 
disclose that a six-layer structure of polypropylene/adhesive 
layer/ethylene-vinyl alcohol copolymer/adhesive layer/recycled 
plastics/polypropylene, which is formed by coextrusion and blow molding 
and in which ethylene-vinyl alcohol copolymer (EVOH) is used as barrier 
layer, can effectively act as a barrier to the permeation of gases. U.S. 
Pat. Nos. 3,857,754 and 3,975,463 disclose a structure of three layers 
having improved barrier properties which can be formed from a homogeneous 
molten blend of polyolefin, saponified ethylene-vinyl acetate copolymer 
and a carbonyl-containing thermoplastic polymer by utilizing high shear 
equipment. U.S. Pat. No. 3,873,667 discloses a heat treatment process for 
decreasing the permeability of gases through a homogeneous composition of 
polyolefin and polyamide. U.S. Pat. No. 3,093,255 discloses a method for 
preparing polyolefin/polyamide blends by subjecting them to intensive 
mixing under high pressure. U.S. Pat. Nos. 3,373,222, 3,373,223 and 
3,373,224, all disclose dispersant materials such as carboxylated 
polyethylene, ethylene-acrylic acid copolymer and ethylene-metchacrylic 
acid copolymer and ionized ethylene-unsaturated carboxylic acid copolymer, 
that are used to enhance the barrier and mechanical properties of 
polyolefin/polyamide blends. U.S. Pat. Nos. 4,410,482 and 4,444,817, 
disclose alkyl carboxyl-substituted polyolefins used as compatabilizers 
for polyolefines and condensation polymer blends. The resulting blends can 
be fabricated into laminar articles having improved barrier properties to 
the permeation of organic solvents and gases. 
SUMMARY OF THE INVENTION 
The object of the invention is to provide a polyolefine composition which 
can easily be fabricated into laminar articles having higher barrier 
properties to the permeation of organic solvents and gases, and 
simultaneously display good impact resistance and dimensional stability. 
The polyolefin composition of the invention is a blend of a polyolefin and 
a modified polyamide. In fabricated laminar articles, the polyolefin is 
present as a continuous matrix phase and the modified polyamide is present 
as a discontinuous distributed phase. The modified polyamide includes 3-60 
percent by weight of a compatabilizer. The compatabilizer can be a 
polyether ester amide block copolymer or a mixture of said polyether ester 
amide block copolymer and an alkyl carboxyl-substituted polyolefin. 
The laminar articles of the invention can be fabricated directly from the 
blend by, for example, extrusion blow molding method, and the like. 
The present invention can be more completely understood by reference to the 
following detailed descriptions.

DETAILED DESCRIPTION OF THE INVENTION 
According to the invention, the polyolefin constitutes 60-98 percent by 
weight of the composition. Examples of the polyolefin include but are not 
limited to polyethylene, polypropylene, polybutylene, and copolymers of 
these materials and the like. Among them, polyethylene(PE) is preferred, 
and may be high, medium or low density. 
The modified polyamides constitute 2-40 percent by weight of the 
composition, and are a blend of 97-40 percent by weight of aliphatic 
polyamides or semi-aromatic polyamides or the mixture thereof, and 3-60 
percent by weight of compatilizers. 
Aliphatic polyamides are made by reacting carboxylic acids with primary 
amines under well-known conditions, or prepared from lactams or 
aminocarboxylic acids. Examples of carboxylic acids used in polyamide 
preparation are adipic acid, suberic acid, sebacid acid, azelaic acid, 
malonic acid, glutaric acid, pimelic acid, docecanic acid, and the like. 
Examples of primary amines are tetramethylene amine, pentamethylene amine, 
hexamethylene amine, octamethylene amine and the like. Examples of 
aliphatic polyamides include but are not limited to polypentamethylene 
adipamide, polyhexamethylene adipamide, polyhexamethylene azelamide, 
polyhexamethylene sebamide, polyhexamethylene dodecanamide, 
polyhexamethylene sebacamide, caprolactams, and polyamides obtained from 
amino acids such as 11-aminoundecanoic acid, and the like. 
Semi-aromatic polyamides suitable for use in the invention are those 
prepared from (1) 100 mole % of terephthalic acid and a mixture of 40-60 
mole % of 2,2,4-trimethyl hexadiamine and 60-40 mole % of 2,4,4-trimethyl 
hexadiamine; (2) a mixture of 60-90 mole % isophthalic acid and 10-40 mole 
% of terephthalic acid and a mixture of 80-98 mole % of hexadiamine and 
2-20 mole % of at least one C.sub.8 -C.sub.20 aliphatic diamine 
(containing at least one cyclohexane, for example 
1-amino-3-aminomethyl-3,5,5-trimethyl cyclohexane, 
1,4-bis(aminomethyl)cyclohexane and bis(ortho-aminocyclohexyl) methane); 
and (3) 100 mole % of adipic acid and a mixture of 70-100 mole % of 
isophthalic diamine and 0-30 mole % of hexamethylene diamine, and the 
like. 
The compatabilizer suitable for use in the invention can be a polyether 
ester amide block copolymer in which the rigid segments are polyamides 
such as nylon 4-6, 6-10, 6-12, 6, 11, and 12 and the flexible segments are 
polyethyl glycol, polypropyl glycol, polyethylene glycol, 
polytetramethylene glycol, polycaprolactone diol, polycarbonate diol and 
the like. 
The compatabilizer can also be a mixture of said polyether ester amide 
block copolymer and alkylcarboxyl-substituted polyolefin, in which the 
alkylcarboxyl-substituted polyolefin constitutes up to 85 percent by 
weight of the mixture. 
The alkylcarboxyl-substituted polyolefin compatibilizer is a polyolefin 
which has carboxylic moieties attached thereto, either on the polyolefin 
backbone itself or on side chains. The term "carboxylic moiety" means 
carboxylic groups from the group consisting of acids, esters, anhydrides, 
and salts. Carboxylic salts are neutralized carboxylic acids, and a 
compatibilizer which includes carboxylic salts as a carboxylic moiety also 
includes the carboxylic acid of that slat. Such compatibilizers are termed 
ionomeric polymers. 
Compatibilizers can be prepared by direct synthesis or by grafting. An 
example of direct synthesis is the polymerization of an .alpha.-olefin 
with an olefinic monomer having a carboxylic moiety; and an example of 
grafting is the addition of a monomer having a carboxylic moiety to a 
polyolefin backbone. When the compatibilizer is made by grafting, the 
polyolefin is a polyethylene; or a copolymer of ethylene and at least one 
.alpha.-olefin of 3-8 carbon atoms such as propylene, and the like; or a 
copolymer including at least one .alpha.-olefin of 3-8 carbon atoms and a 
diolefin, such as 1, 4-hexadiene, and the like. The polyolefin is reacted 
with an unsaturated carboxylic acid, anhydride, or ester monomer to obtain 
the grafted polymer. Representative eligible acids, anhydrides, and esters 
include: methacrylic acid; acrylic acid; ethacrylic acid; glycidyl 
methacrylate; 2-hydroxy ethylacrylate; 2-hydroxy ethyl methacrylate; 
diethyl maleate, monoethyl maleate; di-n-butyl malcate; maleic anhydride; 
maleic acid; fumaric acid; itaconic acid; monoesters of such dicarboxylic 
acids; dodecenyl succinic anhydride; 3-norbornene-2, 3-anhydride; nadic 
anhydride (3,6-endomethylene-1,2,3, 6-tetrahydrophthalic anhydride); and 
the like. Generally, the graft polymer will have from about 0.01 to about 
20, preferably about 0.1 to about 10, and most preferably about 0.2 to 
about 5, weight percent graft monomer. 
When the compatibilizer is made by direct synthesis, the polymeric material 
is a copolymer of an .alpha.-olefin of 2-10 carbon atoms and an .alpha., 
.beta.-ethylenically unsaturated carboxylic acid, ester, anhydride, or 
salt having 1 or 2 carboxylic moieties. The directly synthesized 
compatibilizer is made up of at least 75 mole percent of the olefin 
component and from about 0.2 to 25 mole percent of the carboxylic 
component. 
The ionomeric compatibilizer is preferably made of directly synthesized 
compatibilizer and of about 90 to 99 mole percent of olefin and about 1 to 
10 mole percent of .alpha., .beta.-ethylenically unsaturated monomer 
having carboxylic moieties, wherein the moieties are considered as acid 
equivalents and are neutralized with; (1) metal ions having valences of 1 
to 3, inclusive, when the carboxylic acid equivalent is monocarboxylic, 
and (2) metal ions having a valence of 1 when the carboxylic acid 
equivalent is dicarboxylic. To control the degree of neutralization, metal 
ions are present in an amount sufficient to neutralize at least 10 percent 
of the carboxylic moieties. Representative eligible 60 -olefins and 
unsaturated carboxylic acid, anhydride, and ester monomers are those 
previously described herein. 
The modified polyamides of the invention are obtained by first blending the 
previously described polyamides and compatabilizers, and then extruding by 
using, for example, a single screw or twin screw extruders, and are then 
pelletized. The pelletized, modified, polyamides thus obtained have 
excellent adhesion to polyolefins, and thus can be blended with 
polyolefins and then fabricated into laminar, shaped articles directly by, 
for example, blow molding, co-extrusion, or sheet extrusion molding 
methods. Additives which will not influence the formation of laminar 
structure and the desired physical properties of the articles, for 
example, colorants, lubricants, stabilizers and fillers, can be added to 
the blend prior to the fabrication process. 
The laminar, shaped articles of the invention display good barrier 
properties to various organic liquids, such as commerical-use solvents, 
thinners or dispersants. Typical organic liquids include aliphatic 
hydrocarbons, e.g. crude gasoline, heptane, aromatic hydrocarbons, e.g. 
toluene and xylene, and halogenated hydrocarbons, e.g. trichloro ethane, 
and ortho-dichloro benzene. The polyolefin/modified polyamide composition 
of the invention also has good barrier properties to the vapors of the 
above organic fluids. 
The following example illustrates the invention without limiting its scope. 
EXAMPLE 
Modified polyamides A, B, C and D were prepared by blending polyamides, 
polyether ester amide block copolymer and modified polyolefins and then 
mixing in an extruder at 220.degree. C.-260.degree. C., and were then 
pelletized. The weight ratios of each components of the blend are 
summarized in Table 1 below. 
TABLE 1 
______________________________________ 
modified polyether ester block 
polyamide 
polyamide copolymer modified polyolefin 
______________________________________ 
A 94.sup.(1) 
6 -- 
B 85 5 10.sup.(2) 
C 75.5 4.5 20 .sup. 
D 94.sup.(3) 
6 -- 
______________________________________ 
Note: 
.sup.(1) Nylon 6 
.sup.(2) maleic anhydride modified high density PE, 0.22 weight percent 
grafted 
.sup.(3) Zytel 330 (E.I. du Pont de Nemours and Company, semiaromatic 
amorphous nylon) 
Blends 2, 3, 4, 5, 6 and 7 were prepared by blending thoroughly high 
density polyethylene and the above obtained modified polyamides. The 
weight ratios of the high density PE and modified polyamides are 
summarized in Table 2. Blends were then fed into a low shear extrusion 
blow molding machine, and bottles with a capacity of about 1 liter were 
blow molded at an extrusion temperature of about 225.degree. C. As a 
control, bottles were also made from blend 1 which is a mixture of high 
density PE and commerical available Nylon 6 in the same extrusion blow 
molding machine at the same extrusion temperature. 
TABLE 2 
______________________________________ 
High density Modified 
Blend P.E. Nylon 6 polyamide 
______________________________________ 
1 93 7 -- 
2 97 -- 3(A) 
3 90 -- 10(A) 
4 93 -- 7(B) 
5 95 -- 5(B) 
6 95 -- 5(C) 
7 90 -- 10(D) 
______________________________________ 
Bottles thus formed were tested for permeation of xylene and impact 
strength. Barrier to permeation was tested by adding 800 g of xylene to 
bottles, sealing the bottles, and then determining the weight loss after 
30 days at a temperature of about 25.degree. C. and a relative humidity of 
less than 50%. Impact strength was tested by filling the bottles with 
water, sealing the bottles and then letting them free fall from a 
1.2-meter height. Test results are summarized in Table 3. 
TABLE 3 
______________________________________ 
Permeation barrier 
(g-loss) Impact Strength 
______________________________________ 
High density PE 
22.95 not broken 
Blend 1 2.27 broken 
Blend 2 1.00 not broken 
Blend 3 0.24 not broken 
Blend 4 0.22 not broken 
Blend 5 0.32 not broken 
Blend 6 0.42 not broken 
Blend 7 0.31 not broken 
______________________________________ 
As shown in Table 3, the bottles of the invention exhibited excellent 
barrier properties to permeation of xylene as opposed to the bottles 
prepared from high density PE or a blend of high density PE and unmodified 
polyamide, as well as good impact strength.