Note: Descriptions are shown in the official language in which they were submitted.
3. Detailed Description of the Invention
[Industrial Field of Utilization]
The present invention provides a saponified
ethylene-vinyl acetate copolymer composition markedly
improved in long run property in melt-molding and in
quality.
~Prior Art]
Saponified etnylene-vinyl acetate copolymers are
excellént in variols properties such as oxygen barrier
property, mechanical strength, etc., and therefore have
found application _n various uses such as film, sheet,
container material, textile fiber and so on.
However, since such saponified copolymers are
highly hygroscopic, shaped articles based on these
materials are disadvantageous in that they undergo
marked change in p;~ysical properties such as flexibility
according to changes in the humidity and temperature of
the ambient atmospnere and, in particular, their oxygen
barrier property s so highly dependent on humidity
that they do not effectively seal off oxygen in a
high-humidity env_ron~ent.
~ ~-v r r~
Furthermore, because of poor stretchability and
flexibility, shaped articles based on this type of
copolymer readily undergo uneven stretching in the
course of deep-drawing or other molding procedures
involving stretchinq and/or give pinholes in use after
molding, imposing limitatlons on their use as packaging
materials. Therefore a polyolefin resin is often
admixed with said saponified copolymers.
However, such resin mixtures as mentioned above
are inferior in the so-called long run property. ~hen
they are used to produce films, sheets and the like
shaped articles by melt-molding, for instance, said
mixture compositions undergo gelation during molding
and/or give, during molding, thermally discolored or
carbonized resins (the so-called scorches), which
adhere to the extruder inside. Accordingly the melt
molding cannot be done continuously for a prolonged
period of time. To cope with this probiem, the com-
bined use of a hydrotalcite solid solution has been
proposed as a measure therefor.
[Problems which the Invention is to solve]
Recent technological innovations and social needs
for higher quality snaped articles have emphasized the
necessity of developing novel saponified ethylene-~inyl
acetate copolymer compositions much more improved than
~3~ 2
the conventional ones.
More specifically, the prior art compositions are
often used in the form of laminates with a polyolefin
or polyester or the like thermoplastic resin. When
exposed to a high-temperature high-humidity atmosphere,
. the laminates in the form of packaging materials for
retortable foods, or instance, often undergo decrease
in interlayer adhesion, which may lead to the occur-
rence of the phenomenon of peeling or whitening (blush-
ing). Development of improved compositions is strongly
demanded.
[Means for Solving ,he Problems]
The inventors of the present invention made
intensive investigations in an attempt to develop a
saponified ethylene-vinyl acetate copolymer composition
having excellent long run property and ensuring higher
quality characteristics as compared with the conven-
tional compositions, for example markedly improved
interlayer adhesion, among others, even in a high-
temperature high-h~midity atmosphere, with the oxygen
barrier property in~rinsic of the saponified copolymer
being retained at a high level. As a result, they
found that the objects such as mentioned above can be
accomplished by a ~esin composition which comprises
(A) a saponified ethylene-vinyl acetate copolymer,
~B) a polyolefin resin,
(C) A graft polymer obtained by grafting an ethylenic-
ally unsaturated carboxylic acid or a derivative
thereof to a polyolefin resin and reacting the adduct
with a polyamide oligomer, and
(D~ a hydrotalcite solid solution representable by the
general formula
)yl(M )y2]1-xr~ (oH)2Ax/n~mH2o
wherein M2+ represents at least one metal selected from
among Mg, Ca, Sr and Ba, M2 is a metal selected from
among Zn, Cd, Pb and Sn, M3 is a trivalent metal, An
is an anion having a valence of n, and. x, yl, y2 and m
are respectively positive numbers satisfying the
conditions 0 < x ' 0.5, 0.5 < yl < 1, yl + y2 = 1, and
0 S m < 2. The present invention has been completed
based on the above finding.
The present invention will hereinafter be de-
scribed in detail, with emphasis placed on such composi-
tion and, in particular, on uses for shaped articles
based thereon.
The saponified ethylene-vinyl acetate copolymer
~A) to be employed in accordance with the present
invention should have an ethylene content of 2Q to 60
mole %, preferably 25 to 55 mole %, with a degree of
saponification of its vinyl acetate component being not
less than 95 mole %.
With an ethylene content less than 20 moie %, the
oxygen barrier property under high-humidity conditions
is not as high as desired, while an ethylene content in
excess of 60 mole % leads to decreases in o~gen
barrier property, printability and other phys-cal
properties. When the degree of saponificatiGn or
hydrolysis is less than 95 mole %, the oxygen barrier
property and moisture resistance are sacrificed.
It should be understood that this sapon~ ied
copolymer may contain small proportions of o~;.er
comonomer ingredients including a-olefins such as
propylene, isobutene, a-octene, a-dodecene, ~-octa-
decene, etc., unsatura~ed carboxylic acids o_ salts
thereof, partial alkyl esters, complete alkyl esters,
nitriles, amides and anhydrides and unsatura__d sulfon-
ic acids or salts thereof.
With regard to the above component (A), -ts melt
flow rate (hereinafter referred to briefly as ;~FR) M
as determined at 210C and under a load of G ~O g
according to JIS K-6760 is suitably in the range of 0.5
to 100 g/lO minutes and preferably 1 to 60 g/:0 minutes.
With regard to the polyolefin resin (~), there may
be mentioned linear low-density polyethylene, low-,
~3~
medium- and high-density polyethylenes, ionomers,
ethylene-propylene copolymer, crystalline polypropyl-
ene, polybutene, ethylene-vinyl acetate copolymer of
comparatively low vinyl acetate content, and so on.
Particularly, low-, medium- or high-density polyethyl-
ene, and isotactic polypropylene are of practical
importance.
With regard to (B~, it is advantageous that its
melt flow rate as determined at 210C and under a load
of 2160 g according to JIS ~-6760 is in the range of
0.01 to 100 g/10 minutes.
~ or improving the compatibility among the
components of the desired resin composition,
incorporation of (C) is essential in the practice of
the invention.
The component (C) is a graft polymer obtainable by
grafting an ethylenically unsaturated carboxylic acid
or a derivative thereof to a polyolefin resin and
reacting this carboxylic acid or derivative thereof
with a polyamide oligomer.
This graft polymer can be produced by dissolving
or suspending a polyolefin resin in an appropriate sol-
vent or putting it in a molten state, activating the poly-
olefin resin chain with a peroxide or diazo initiator,
grafting an ethylenically unsaturated carboxylic acid or a
- 7 -
2 ~ ~ 3~
derivative thereof thereto to give a polymer and mixing
this polymer with a polyamide oliyomer in molten state.
For this reaction, Brabender machine, Buss blender,
s-ngle-screw extruder, Werner and ~fleiderer twin-screw
extruder or the like is employed.
- The degree of polymerization of the polyolefin
resin to be employed is about 350 to 45,000 and prefer-
ably about 500 to 10,000. The melt flow rate ~230C,
load 2160 g; the same applies hereinafter) is about 0.1
to 50 g/10 minutes for all practical purposes.
~ he reaction ratio of the polyolefin resin to the
ethylenically unsaturated carboxylic acid or a derlva-
tive thereof is 100/0.05 through 100/10 and preferably
100/0.5 through 100/3 as expressed on the weight basis.
If the ratio is 100/less than 0.05, the improving
effect on compatibility will not be sufficient. On the
other hand, if the ratio is 100/more than 10, the
viscosity will be too high for practical molding.
The degree of polymerization of said polyamide
oligomer is 5 to 80, preferably about 15 to 55, for all
practical purposes and the reaction ratio is 0.01 to 1
mole and preferably 0.05 to 0.9 mole per mole of the
carboxyl group.
As examples of the polyolefin resin, there may be
mentioned linear low-density, low-density, medium-
-- 8
density or high-density polyethylene, ionomers, ethyl-
ene-propylene copolymer, crystalline polypropylene,
polybutene, ethylene-vinyl acetate copolymer, ethylene-
propylene copolymer and so on. Important for practical
purposes are linear low-density polyethylene, low-
density polyethylene, high-density polyethylene,
ethylene-propylene copolymer, ethylene-vinyl acetate
copolymer and crystalline polypropylene.
The ethylenically unsaturated carboxylic acid or
derivative thereof to be grafted to such a trunk
polymer includes, among others, unsaturated carboxylic
acids such as acrylic acid, methacrylic acld, crotonic
acid, maleic acid, fumaric acid and itaconic acid, and
the corresponding anhydrides or half esters.
The polyamide oligomer can be prepared by the
known methods such as addition polymerization of a
lactam, polycondensation of an aminocarboxylic acid,
polycondensation of a diamine with a dicarboxylic acid,
and so on.
~ xamples of the starting materials for said
polyamide oligomer are various lactams such as ~-capro-
lactam, enantholactam, caprylolactam, laurolactam,
a-pyrrolidone, a-piperidone, etc., ~-amino acids such
as 6-aminocaproic acid, 7-aminoheptanoic acid, 9-amino-
nonanoic acid, 11-aminoundecanoic acid, etc., dibasic
g
acids such as adipic acid, glutaric acid, pimellic
acid, suberlc acid, azelaic acid, sebacic acid, un-
decadioic acid, dodecadioic acid, hexadecadioic acid,
hexadecenedioic acid, eicosadioic acid, eicosadiene-
dioic acid, diglycolic acid, 2,2,4-trimethyladipic
acid, xylylenedicarboxylic acid, 1,4-cyclohexanedi-
carboxylic acid, terephthalic acid, isophthalic acid,
etc., and diamines such as hexamethylenediamine,
tetramethylenediamine, nonamethylenediamine, undeca-
methylenediamine, dodecamethylenediamine, 2,2,4- (or
2,4,4-)trimethylhexamethylenediamine, bis(4,4'-amino-
cyclohexyl)methane, metaxylylenediamine and so on. For
molecular weight control, a monoamine such as lauryl-
amine or oleylamine can also be used in an appropriate
amount.
In the composition of the present invention, the
proportion of (A) should be 50 to g9.5 weight O and
preferably 60 to 95 weight %, that of (B) should be 0.4
to 50 weight % and preferably 4.5 to 35 weight -0, and
that of (C) should be 0.1 to 15 weight ~ and preferably
1.5 to 10 weight %.
When the proportion of (A) is less than 50 weight
% or that of (B) is over 50 weight %, the oxygen
barrier property is adversely affected. Conversely
when the proportion of ~A) is over 99.5 weight % or
-- 10 --
that of (B) is less than 0.4 weight ~, stretchability
and flexibility are sacrificed. When the proportion of
(C) is less than 0.1 weight %, the compatibility
between (A) and (B) is poor, so that the interlayer
adhesion of laminates decreases. Conversely when the
proportion of (C) exceeds 15 weight %, long-run mold-
ability is adversely affected.
The component (D) to be employed in accordance
with the present invention is a hydrotalcite solid
solution representable by the general formula
[( )yl(M )y2]1-xM (OH)2Ax~n.mH2o
wherein M2 represents at least one metal selected from
among Mg, Ca, Sr and Ba, M2 is a metal selected from
among Zn, Cd, Pb and Sn, M3+ is a trivalent metal, An
is an anion having a valence of n, and x, yl, y2 and m
are respectively positive numbers satisfying the
conditions O ~ x ' 0.5, 0.5 < yl < 1, yl + y2 = 1, and
O ~ m < 2.
With regard to the above general formula, M2 is
preferably Mg or Ca and M2 is desirably Zn or Cd. M3+
includes, as examples thereof, Al, Bi, In, Sb, B, Ga
and Ti. Among them, Al is suited for practical use.
Useful as A are C03 , OH , HC03 , salicylate
ion, citrate ion, tartrate ion, N03 , I , oxalate ion,
[Fe(CN)6]4 , Cl04 , CH3COO , maleate ion and the like.
-- 11 --
:
The hydrotalcite solid solution may be surface-
treated with a higher fatty acid, anionic surfactant,
silane coupline agent, titanate coupling agent, glycerin
fatty acid ester or the like.
Typical examples of (D) are as follows:
0-75 0.25]0.67Al0.33(H)2(C3)0 165--45H2
[MgO 79Zno 21]0 7Alo.3( OH)2(co3)o.15
1/7 3/7 3/7]o.7Alo.3(oH)2(cHcoo) o.4lH2o
CHCOO o 15
[ g6/7Cdl/7]0.7P~l0.3(0H)2(cH3coo)o 3-0.34H20
[Mg5/7pb2/7]o 7Alo 3(0H)2(C03)o 15-0.52H20
[ gO.74zno.26]o.68Alo 32(H)2(C3)0 16
0-56 0.44]0.68A10.32(0H)2(Co3)0 16-o-2H2o
[ go.8lzno.ls]o.74Alo.26(oH)2(co3)o 13
0-75 3-25]0.8AlQ.2(oH)2(co3)0 1o-0.16H20
[MgO 71ZnO 29]0.7Al0.3(H)2( 3)0-30
[Mg0.7lzno.29]o.7 10.3( )2(11 )
CHC 0.15
[ gO .14CaO . 57ZnO . 29 ] 0 - 7A10 3 ~ OH~ 2 3 25H2o
The component (D) is used in an amount of 0.005 to
5 parts by weight, prefexably 0.01 to 1 part by weight,
per 100 parts by weight of the sum total of (A) plus
(B) plus (C).
When the amount of (D) is smaller than O.005 part
by weight, the long-run moldability is low while films
. - 12 -
2~3~7~
will have decreased transparency, stretchability and
flexibllity when said amount exceeds 5 parts by weight.
The component ~D) may be present in any form in
the mixture of (A), (BJ and (C~. The time of addition
of (D) is not critical. It is advantageous, however,
to admix (D) with the polyolefin resin (B) in advance
and then blend the masterbatch-like mixture with the
components (A) and (C).
While the composition according to the present
invention is useful for a variety of applications such
as shaped articles, adhesives, coatings and so on, it
is most useful for molding purposes and can be molded
into pellets, film, sheet, containers, fibers, bars,
pipe and other shaped articles by the melt-kneading
technique. Such products can be crushed (for reclaim-
ing) or pelleted for re-melt-molding.
For melt-molding of the composition, extrusion
molding ~e.g. T-die extrusion, inflation molding, blow
molding, melt spinning or contour extrusion) and
injection molding are mostly employed. The melt-
molding temperature is selected in many cases from the
range of 170 to 270C. In addition to the above
techniques, two-color molding and injection-blow
molding techniques may also be employed and shaped
articles with good dimensional tolerances can be
- 13 -
2 ~ 3 ~
manufactured.
In the molding process, it is of course possible
to use two or more different saponified ethylene-vinyl
acetate copolymers varying in ethylene content and/or
in the degree of saponification in combination. In
melt-molding, it is also possible to incorporate,
besides the above-mentioned saponified ethylene-vinyl
acetate copolymer, suitable amounts of additives such
as a plasticizer (for example, a polyhydric alcohol),
stabilizer, surfactant, crosslinking agent (for example,
an epoxy compound, polyvalent metal salt, inorganic or
organic polybasic acid or salt thereof), filler,
colorant, reinforcing fiber ~for example, glass fiber,
carbon fiber, etc.), and so on. Any other thermo-
plastic resin may also be incorporated. Such thermo-
plastic resin includes, among others, polyolefins other
than the component (B) mentioned above (linear low-
density, low-density or high-density polyethylene,
polypropylene, ethylene-propylene copolymer, ethyl-
ene-propylene-diene copolymers, copolymers of ethylene
and an alpha-olefin containing 4 or more carbon atoms,
ethylene-vinyl acetate copolymer, ethylene-acrylate
ester copolymers, ionomers, polybutene, polypentene,
etc.), modified polyolefins obtainable by graft-modi-
fication of such polyolefins with unsaturated carboxylic
- 14 -
~ ~ ~ 3
acids or derivatives thereof, polyamides, polyvinyl
chloride, polyvinylidene chloride, polyesters, poly-
styrene, polyacrylonitrile, polyurethanes, polyacetal,
polycarbonates, melt-moldable polyvinyl alcohol resin
and so on.
As mentioned hereinbefore, the composition of the
present invention is not only used for the manufacture
of a single-layer article solely composed of the
composition but also used often as a laminated article
including at least one layer of the composition.
The layer of the composition of the present
invention shows a characteristically high bonding
affinity for the layer material to be laminated there-
with. In particular, said bonding affinity can be
retained at a high level even under high-temperature
high-humidity conditions in retorts and the like.
In the manufacture of a laminated product accord-
ing to the invention, in which a different material is
laminated to one side or either side of a layer of the
composition of the invention, the following laminating
methods, for instance, can be employed. Thus, the
method which comprises melt-extruding a thermoplastic
resin onto a film or sheet of the composition of the
invention, the method which comprises melt-extruding
the composition of the invention onto a substrate made
- 15 -
2~3~ 7~
of a thermoplastic resin or some other material, the
method which comprises co-extruding the composition of
the invention and a different thermoplastic resin, and
the method in which a film or sheet of the composition
of the invention is laminated to a film or sheet of a
different material with a known adhesive such as an
organotitanium compound, an isocyanate compound or a
polyester compound can be mentioned.
As mating resins for co-extrusion, there may be
mentioned linear low-density polyethylene, low-density
polyethylene, medium-density polyethylene, high-density
polyethylene, ethylene-vinyl acetate copolymer, ionomers,
ethylene-a-olefin (C3 20 a-olefin) copolymers, ethylene-
acrylic ester copolymers, polypropylene, propylene-a-
olefin (C4 20 a-olefin) copolymers, homo- or copolymers
of olefins such as polybutene, polypentene, etc., and
polyolefin resins in a broad sense as obtainable by
modifying such homopolymers or copolymers of olefins by
grafting of an unsaturated carboxylic acid or an ester
thereof, polyesters, polyamides, copolymerized poly-
amides, polyvinyl chloride, polyvinylidene chloride,
acrylic resins, styrenic resins, vinyl ester resin,
polyester elastomers, polyurethane elastomers, chlo-
rinated polyethylene, chlorinated polypropylene and so
on. A saponified ethylene-vinyl acetate copolymer can
- 16 -
2 ~ ?~ a~ J
also be co-extruded.
When a film or sheet or the like shaped article is
prepared from the composition of the invention and,
then, extrusion-coated with a different material or
laminated to a film or sheet of a different material
with an adhesive, said different material is not
limited to said thermoplastic resins but may be vir-
tually any other material (such as paper, metal foil,
uniaxially or biaxially oriented plastic film or
sheet, woven fabric, nonwoven fabric, metal filament,
wood and so on).
The laminar structure of sald laminated product is
optional. Thus, a layer of the composition of the
invention being designated as A (A1, A2, ) and a
layer of a different material, e.g. a thermoplastic
resin, being designated as B (B1, B2, ), not only a
two-layer structure of A/B but a variety of other
combinations such as B/A/B, A/B/A, A1/A2/B, A/B1/B2,
B/A/B, B2/B1/A/B1/B2, etc. can be employed for a film,
sheet or bottle, for instance. In the case of a
filament, a bimetal-type, core (A) - sheath (B), core
(B) - sheath (A), eccentric core-sheath and other
combinations of A and B can be adopted.
For co-extrusion, A may be blended with B or vice
versa, or for improved interlayer adhesion, a suitable
~$~Jc~s 2
resin may be incorporated in at least one of A and B.
The laminated product may be optionally configured.
Thus, film, sheet, tape, bottle, pipe, filament, or
modified cross-section extrudate may be mentioned.
The laminated product may, if necessary, ~e
further subjected to a variety of processings, such as
heat treatment, cooling, rollinq, printing, dry lamina-
tlon, solution- or melt-coating, bag production,
deep-drawing, box-making, tubing, splitting and so on.
The aforementioned shaped articles and laminated
products, in particular in the form of film or sheet,
can be improved in physical properties by stretching or
drafting, if required.
In the present invention, the composition is
melt-molded into a film material. The thickness of
such film is virtually optional and may range from a
few microns to several hundred microns. The term
'film' as used in this specification means a film in
the broad sense of the term, thus including a sheet,
tape, tube, container and so on.
The film obtained in the above manner is condi-
tioned for absorption of moisture or drying, if neces-
sary, and then stretched.
This stretching may be uniaxial or biaxial. The
effects of the invention are better materialized when
- 18 -
2 ~
the stretching ratio or draft is as high as possible.
In the case of uniaxial stretching, the stretching
ratio is preferably at least 1.5 times and, for still
better results, not less than 2 times. In the case of
biaxial stretching, the stretching ratio is preferably
not less than 1.5 times, more desirably not less than 2
times and, for still better results, not less than 4
times on the area basis.
As to the stretching technique that can be em-
ployed, there may be mentioned roll stretching, tenter
stretching, tubular stretching and stretching blow
processes, as well as high-draft deep drawing or vacuum
molding. In the case of biaxial stretching, whichever
of concurrent biaxial stretching and serial biaxial
stretching can be adopted.
The stretching temperature is selected from the
range OI about 40 to 150C.
After completion of stretching, the product is
thermally set. This thermal setting can be effected by
the well-known technique. Thus, with the stretched
film being held in taut condition, it is heat-treated
at a temperature of S0 to 160C, preferably at 80 to
160C for about 2 to 600 seconds.
The resulting oriented film can be subjected to a
variety of processings such as cooling, rolling,
-- 19 --
~ ~3 C~S ~ 'J i ~
printing, dry lamination, solution- or melt-coating,
bag-making, deep-drawing, box-making, tubing, splitting
and so on.
The film, sheet or container obtainable from the
composition of the present invention is useful for
packaging foodstuffs, pharmaceutical products, in-
dustrial chemicals, agrochemical products and so on.
[Effects]
The composition according to the invention which
comprises (A), (B~, (C) and (D) is excellent in long
run property and the shaped articles obtained therefrom
are characterized by their markedly improved interlayer
adhesion, oxygen barrier property, stretcha~sility and
flexibility.
[Examples]
The following examples are further illustrative of
the composition of the present invention. In the
following description, all parts and % are by weight
unless otherwise indicated.
- 20 -
2~33~ 7~
Saponified ethYlene-vinyl acetate co~olYmer
Sample E-l E-2 E-3 E-4
Ethylene content 30 33 40 45
(~ole %)
Degree of saponification of
vinyl acetate component 99.4 99.1 99.6 99.7
(mole ~)
Polyolefin resin
MFR Melting point
Sampie l jlO min.) (C)
P-l Polypropyiene 3 166
P-2 Ethylene-propylene ~lock copolymer 5 163
(Ethylene content 12~)
P-3 Ethylene-propylene rando~ copolymer 8 165
(Ethylene content 3%)
P-4 Polypropylene 8 166
P-5 Linear low-density polyethylene 4 124
_
P-6 High-density polyethylene 1.2 134
- 21 -
~ Y~1 ~ J ~3
.~ S' E a~ a~
C ~ ,_ 0_ h ~ N N
~r ~ r r o
J NO 3 Eo N O t~
CJl--I 0 0 ~ ~ O
.' :~ ~ WO~
1_1 ~ o ,1 h
~1 a) ~ c ~ ~
:: a) ^c ~ ~ o0 0
~ _ UC ~1 0 ~ .
r~ ~ ~ . 0 ~ ~ ~1 ^ _
o, c o~1 JJ a) --I --I o
_I X 0 ,
o O 0
:~: G :~: :~ ~a ~ --
rl
ô
_ ~ ~ ~ .r~
~ ~ h E ~-
O I O ^
O t) ~D :~V ~ ~ Ir~ u~
I o a~ I'') c ~ _, N N
N ~I t.) C _ 0
a) E --I ~J E o N
-- O ~~ tl. O ~
C~C 0 ~1
L~ :~ W O
r~
C 1~ ~
W - C'{1 N
Q. E gc u -- ~
~ I D~ W ~ 0 N N
~ c g al0 o ~ o
_ y ~,~ Ll- O O
- ~u~ _l ~1 0
^0 ~ .n O,) ~J ~
. .,~ ~ L:^ ~ O
h h C U ~ ~ O -- ~
8 ~ E E 0 _~ . . ~ 0 0
~ ~ ~ a~ u ~ 3 r~ u E J-
_l ~ _l o ~ ~1 a) _ _ ~, _ _
0~ ~ ~ - L~ ~ ~
u~ ~:~ ~ E I c
Y _.L) O 0 O O U
0 C 0 .R _ ~ E v v
h ~c 0 O ~ O ~1 0
-- o u~ h
-- 22 --
2~ 3 ~ 2
Hydrotalcite solid solution
H-1 [MgO 75ZnO 25]0 67Alo.33(H)2(C03)0.165 2
[ g6/7Cdl~7]0 7Alo 3~H)2(CH3C)O 3~0.34H ~
91/7 a3/7Zn3/7]0.7AlO 3(0H)2~cHcoo) 0.41H O
\CHCOO O 15
H-4: [Mg5/7Pb2/7]o 7Alo 3(0H)2(Co3)o.ls 2
Examples 1 through 10 and Comparative ExamPles 1
and 2
Laminates having the construction shown below were
produced using the compositions comprising a combination
of (A), (B), (C) and (D) as specified in Table 1.
Outer layer (I): Polyamide 6.
Intermediate layer (II): Composition according to
the invention comprising (A), (B), (C) and (D).
Adhesive layer (III): Maleic anhydride-modified
ethylene-vinyl acetate copolymer [MFR: 2.1
g/10 minutes (190C, 2160 g)].
Inner layer ~IV): Ethylene-vinyl acetate
copolymer with a vinyl acetate content of 10%
- [MFR: 2 g/10 minutes (l90~C, 2160 g)].
Four-layer laminates with layer thicknesses of
(I)/(II)/(III)/(IV)=20/10/5/20 microns. For
stretchability testing, f~lms with layer
thicknesses 80/40/20/80 microns were used.
Extrusion modlinq conditions
- 23 -
- ~3~v~
Extruder:
40 mm-dia. extruder (for inner layer)
40 mm-dia. extruder (for intermediate layer)
30 mm-dia. extruder (for adhesive layer)
40 mm-dia. extruder (for outer layer)
Screw: For each, L/C = 2.8; compression ratio =
3.2
Speed of screw revolution:
For inner layer : 40 rpm
For intermediate layer: 20 rpm
For adhesive layer : 20 rpm
For outer layer : 40 rpm
Die:
T-Die with a 4-layer combining adapter
Die width: 450 mm
Extrusion temperature:
Extruders for inner, outer and adhesive
layers
C1 = 190C, C2 = 200C, C3 = 210C,
C4 = 220C
Extruder ior intermediate layer
C1 = 180C, t2 = 200C, C3 = 220C,
C4 = 220C
Combining adapter: 210C
T die : 210C
- 24 -
2 ~
The results obtained are shown in Table 1.
The bond strength was measured after retort
treatment (120C x 30 minutes).
The long-run property was evaluated after 96 hours
of continuous extrusion molding, followed by disjointing
of the extruder, in terms of the state of gel adhesion
on the screen mesh as rated on the 5-point scale from 1
(no adhesion) to 5 (adhesion on the whole surface) or
the state of adhesion of a scorched or burnt material
on the screw surface as rated on the 5-point scale from
1 (no adhesion) to 5 (adhesion on the whole surface).
The oxygen permeability was determined with a
MOCON Oxtran 10/50. The stretchability was evaluated
in terms of uneven stretching in simultaneous biaxial
stretching (3 x 3 times) at 90C.
The film impact strength was determined using a
film impact tester (impact head diameter 3/2 inches,
20C x 65% RH).
The resistance to flexural fatigue was evaluated
in terms of the number of bendings until formation of
one pinhole (until an abrupt increase in oxygen per~
meability) with a Gelboflex tester.
- 25 -
; r
8~ ~ ~ o o o o o o o o
F O O O (~ O O O O
0 ~1 U~ O U~ ~ ~ O 11~ O O 1~ ~
0 V _ 1`1 ~1 ~ ~ ~ ~ N ~1
C~
6 u~ o o o u~ o o u~
U C U ~ r~ ~ In ~ r~ ~ r~
~C ,~ ~ _ _ _ _ ~ _
~ ~ 0_
o o o o o o o o
ù ~ al u~ ~D ~ O u~ ~ ~ V
~ ~0~ ~ a) a~ r- ~ co 0 ~
U r ~,
~ ~ ~ ~ ~ ~ ~ O O ~
U~
u ~ r ~ o a~ ~r _ r-~ ~D ~
X ~ ~ _ ~ _ _ _
~ U
~ ~u r~ _~ r~ r~ _ r~ ~ r~
. D cD ~ 1- a
6 ,,
o
. . ~
~,l ~o~
~ ~ ul u) ~n
., h V ~ O _I ~ O rl ~ ~ ~
tJ' 0 h0 ~ o o o o o o o o
C: D~ ~ ~
~a) . o o ut ~ O ~ ~
m ~ ~ o ~ o o o o ~
P.......... ~ t~l N 1~ _I ~
~s~ O O ~, ~ U'l \I~ O Ul O
~_ 2 ~D ~ r- r` ~) Cl~
_~
Ll ~ _I r`J ~ r~l ~ ~ ~ ~ rl ~ ~ ~ ~ ~ ~ ~ ~ ~D _ ~ ~ ~ _ _I ~ u~
~L) W 11~ ~,7 ~ ~ ~ ~ ~ ~ 1~ t,7 T 1~ T ~ ) ~ ~ 1 ~ ~ P t:~ T !~
,~1 ~1 rl ~r Il~ ~D ~_
.
c~w 1 ~3~
,a ~I) a) o o o o
U V _ o .~ ~ o
~ ~ E ~r o o o
U C O O O O
o ~ ~ u~ r N a~ ~
c~ ~ a~ _ ~
. ' .~ 'U~
C h (~) O X Cl
E ::~
C ~ P
u E ~ r ~ ~ r~ ~r
~ ~ U
E~ C ~ ou
O ~ v c~ u ~ ~ ~ ~J
o ~ v C ~
0 ~ vl
~ ~ O r~
L" r~l r o
la
5~ r~ ~ rl ~ r~ r ~ ~ , _l ~ ~
ra kl ~ ~ ~ O
. _~ ~ _
E E~ u~ X
~; ~ . ~
Examples 11 through 15
Inner layer (I) and outer layer (V): Linear
low-density polyethylene (MFR 1.5 g/10
minutes, density 0.920)
Adhesi~e layers (II) and (IV): Maleic anhydride-
modified linear low density polyethylene (MFR
2 g/10 minutes)
Intermediate layer (III): Composition according
to the invention comprising (A), (~), (C) and
(D).
Layer Composition and layer thicknesses (microns):
(I)/(II)/(III)/(IV)/(V) = 20/5/10/5/20
For stretchability testing, the layer thicknesses
80/20/40/20/80 were used.
Extruder:
40 mm-dia. ex~ruder (for inner and outer layers)
40 mm-dia. extruder (for intermediate layer)
30 mm-dia. extruder (for adhesive layers)
Screw: For each, L/D = 28, compression ratio = 3.2
Speed of screw revolution:
For inner and outer layers: 65 rpm
For intermediate layer: 20 rpm
For adhesive layers: 30 rpm.
Die:
T-Die with a 5-layer combining adapter
- 28 -
2 ~ 3 ~ e~ ~ ~
Die width: 450 mm
Extrusion temperature:
Extruders for inner, outer and adhesive layers
C1 = 190C, C2 = 200C, C3 = 210C, C4 = 220C,
Extruder for intermediate layer
. ' C1 = 180C, C2 = 200C, C3 = 220C, C4 = 220C,
Combining adapter 210C
T die 210C
The results obtained are shown in Table 2.
. - 29 -
~, ~ o o o o o 2 ~ r3 ~ ~
~ a) ~ ~ o o o o o
Q)O~- ~ ~ ~7 ~ ~
v ~ E o o u) In o
a~ U r~ _ _ ~ tt~
~ ~,_
0~ 0~ O Ln 1n ~
.` ~ ~
~ ~' ~ ~ ~ ~ ~
e 1 U ~ _ _ ~ ~`J
~ ~U~
.` ~ S~ ~3
h :~ V L~ U ~ _ t~1 r~l _
4~ ~'0
~1 t~ ~q E ~1 _ ~ _
.~ O o
. ' v ~ O + 'n ~ ~ o rl
1~ ~ + o o o o o
~ ~ o o
u7 ~ ~ m ~n
r ~ r r
s~ _ _ ~ ~ ~ r) r~l r~ rl ~ ~ r~ ~r ~ ~ _~
)a ~1.7 ~ ~ ~~ ~ ~7 T ~ ~ ~7 'r ~ ) ~ ~ ~L ~7
_ _ r~ _ n
~3~
[Effect~
The composition according to the invention which
comprises (A) a saponified ethylene-vinyl acetate
copolymer, (B) a polyolefin resin, (C) a specific graft
copolymer and (D) a hydrotalcite solid solution is
excellent in long-run processability and gives shaped
articles having good oxygen barrier property, stretch-
ability and flexibility.
- 31 -
