 |
Description  |
|
|
FIELD OF THE INVENTION
The present invention relates to resin compositions, laminates and block
copolymers which are flexible and excellent in flexural fatigue resistance
and in gas barrier properties.
BACKGROUND OF THE INVENTION
Saponified products of ethylene-vinyl acetate copolymers (hereafter
referred to as EVOH) are widely known as melt-formable thermoplastic
resins that are excellent in gas barrier properties, oil resistance,
solvent resistance, flavor retention properties, etc. and have been used
for films, sheets, containers, etc. in various wrapping arts.
However, EVOH has some disadvantages, such as it is rigid and fragile and
lacks flexibility so that EVOH is scarcely used alone but has mainly been
used in laminates with other thermoplastic resins. But cracks and pinholes
are still formed in the EVOH layer because of violent vibrations, for
example, due to transportation, flexural fatigue, etc. and, therefore, the
excellent gas barrier properties cannot be retained.
SUMMARY OF THE INVENTION
One of the main objects of the present invention is to provide a resin
composition having excellent flexural fatigue resistance and excellent gas
barrier properties.
As a result of extensive investigations, the present inventors have
discovered that the object described above can be achieved by blending
EVOH-type copolymer containing a polyether component with ordinary EVOH.
The present invention is directed to a resin composition comprising 95 to
50 parts by weight of EVOH and 5 to 50 parts by weight of EVOH containing
the polyether component.
The packaging materials composed of the resin composition according to the
present invention are excellent in gas barrier properties, oil resistance,
solvent resistance and flavor retention properties and greatly improve
flexibility and flexural fatigue resistance. The aforesaid resin
composition is extremely useful in various packaging arts not only as
flexible laminate packaging materials but also as flexible single-layer
packaging materials.
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is an NMR spectrum of a reacetylated block copolymer wherein
ethylene-vinyl acetate copolymer is added to both ends of polyoxypropylene
.
DETAILED DESCRIPTION OF THE INVENTION
EVOH used in the present invention is a saponified ethylene-vinyl acetate
copolymer having an ethylene content of 20 to 60 mol%, preferably 25 to 55
mol%, in which the vinyl acetate component has a saponification degree of
at least 95%, preferably 98% or more. When the ethylene content becomes
less than 20 mol%, not only is the formability decreased, but the gas
barrier properties are also reduced under high humidity conditions. When
the ethylene content exceeds 60 mol%, the gas barrier properties are
greatly reduced, which is not preferred. When the saponification degree of
the vinyl acetate component becomes less than 95%, the gas barrier
properties are reduced, which is not preferred. In addition, other
copolymerizable unsaturated monomers may also be included in a range that
does not damage the properties of EVOH.
The term "ethylene content of 20 to 60 mol%" in the EVOH containing the
polyether component indicates the content of ethylene present in the EVOH
from which the polyether component has been excluded. The ethylene content
and the saponification degree of both the EVOH containing the polyether
component and the EVOH blended therewith can be freely chosen in the
ranges described above, but it is preferred that both the ethylene content
and the saponification degree of each is equal or approximately equal, for
example, a difference in the ethylene contents of 20 mol% or less,
preferably 10 mol% or less and a difference in the saponification degree
of 3% or less, preferably 2% or less.
The polyether component, includes a component mainly composed of an
oxyalkylene unit such as an oxyethylene unit, an oxypropylene unit, an
oxyethylene-oxypropylene unit, an oxytetramethylene unit, etc. Among them,
particularly preferred are the oxypropylene unit and the
oxyethylene-oxypropylene unit. The polyether component may further include
a polymethylene unit, an amide group, a urethane group, an ester group, a
phenyl group, etc. therein.
As to the weight ratio of the EVOH component to the polyether component of
the polyether component-containing EVOH copolymer in the present
invention, it is preferred that the polyether component be at least 2 wt%
from the viewpoint of imparting flexibility thereto and in view of
dispersibility upon blending with EVOH, interaction therebetween or gas
barrier properties, the polyether component be 90 wt% or less. As
described above, the polyether component is at least 10 wt%, preferably 20
wt% or more and preferably not greater than 80 wt%, when employing the
polyether component-containing EVOH copolymer as a blend with EVOH.
Processes for preparing the polyether component-containing EVOH copolymer
in the present invention will be described below in detail.
A first type is a block copolymer of polyether and EVOH; where polyether
and EVOH are expressed by P and E, respectively, the block copolymer is
represented by P-E or E-P-E. Such a block copolymer can be prepared, for
example, by the following processes, including a process which comprises
copolymerizing vinyl acetate and ethylene in the presence of polyether
containing a mercapto group(s) at the end(s) thereof (one end or both
ends) followed by saponification in a conventional manner, a process which
comprises polymerizing polyether containing a polymerizable double bond(s)
therein in the presence of ethylene-vinyl alcohol copolymer containing a
mercapto group at one end thereof, etc.
The polyether containing a polymerizable double bond(s) therein as used
herein includes:
a (meth)allyl ether type represented the general formula:
##STR1##
wherein R represents a hydrogen atom or a methyl group; R.sup.1 and
R.sup.2 represents a hydrogen atom or an alkyl group having 1 to 10 carbon
atoms; and R.sup.3 represents a hydrogen atom or an alkyl group having 1
to 10 carbon atoms, an alkyl ester group (having 1 to 10 carbon atoms in
the alkyl group) or an alkylamide group (having 1 to 10 carbon atoms in
the alkyl group), for example polyoxyethylene (meth)allyl ether,
polyoxypropylene (meth)allyl ether, etc.; n represents an integer of 1 to
100;
a (meth)allyl ether type represented by general formula:
##STR2##
wherein R, R.sup.1, R.sup.2 and R.sup.3 are the same as described above;
a (meth)acrylamide type having a double bond at one end thereof represented
by general formula:
##STR3##
wherein R, R.sup.1, R.sup.2, R.sup.3 are the same as described above, and
R.sup.4 represents a hydrogen atom or an alkyl group having 1 to 10 carbon
atoms or
##STR4##
X represents an alkylene group, substituted alkylene group, phenylene
group or substituted phenylene group having 1 to 10 carbon atoms; m
represents 0 or an integer of 1 to 20; each of n and p represents an
integer of 1 to 100 respectively; and R.sup.1, R.sup.2 and R.sup.3 are the
same as described above; for example, polyoxyethylene (meth)acrylamide,
polyoxypropylene (meth)acrylamide, etc.;
a (meth)acrylic acid ester type represented by general formula:
##STR5##
wherein R, R.sup.1, R.sup.2, R.sup.3, X, m and n are the same as described
above, for example, polyoxyethylene (meth)acrylate, polyoxypropylene
(meth)acrylate, etc.; or,
a vinyl ether type represented by general formula:
##STR6##
wherein R.sup.1, R.sup.2, R.sup.3, X, m and n are the same as described
above, for example, polyoxyethylene vinyl ether, polyoxypropylene vinyl
ether, etc.
The next type is a graft copolymer in which polyether is added in a grafted
form as a branch polymer of EVOH. Such a graft copolymer can be obtained,
for example, by copolymerizing ethylene and vinyl acetate together with
polyether containing a polymerizable double bond(s) at the end(s) thereof
followed by saponification in a conventional manner.
A third type is a graft copolymer in which EVOH is added in a grafted form
as a branch polymer of polyether. Such a graft copolymer can be obtained,
for example, by copolymerizaing ethylene and vinyl acetate in the presence
of polyether containing mercapto groups in the side chain thereof followed
by saponification. The processes described above are representative
examples, but the present invention is not deemed to be limited thereto.
The thus obtained polyether component-containing EVOH copolymer has a melt
index (MI) of 0.1 to 250 g/10 mins. The MI as used herein is a value
determined in accordance with ASTM D-1238-65T (2160 g, 190.degree. C.). MI
can be controlled by the degree of polymerization of the EVOH component,
the degree of polymerization of the polyether component and weight ratio
of the EVOH component to the polyether component. In the case of blending
said polyether component-containing EVOH with ordinary EVOH, however, MI
of said polyether component-containing EVOH can be chosen over a wide
range.
The thus obtained polyether component-containing EVOH copolymer is blended
with EVOH. The blending ratio varies depending upon the type, weight ratio
and addition mode of polyether in the EVOH copolymer and further upon the
desired efficiency, but it is generally preferred that the EVOH and the
polyether component-containing EVOH copolymer be contained in 95 to 50
parts by weight and 5 to 50 parts by weight, respectively. It is preferred
that MI or the EVOH used herein be 0.1 to 50 g/10 mins, more preferably
0.1 to 30 g/10 mins, and most preferably 0.1 to 20 g/10 mins. For
blending, there can be adopted known methods such as a melt blending
method using a Banbury mixer, a melt blending method using a single- or
twin-screw extruder, etc.
Upon blending, other additives, for example, antioxidants, UV absorbants,
lubricants, plasticizers, antistatic agents, coloring agents, etc. can be
incorporated therein with a range that does not inhibit the effect and
function of the present invention.
The thus obtained resin composition of the present invention is readily
formable by known melt forming methods and can be formed into optional
forming products such as films, sheets, cups, tubes, bottles, etc. Further
in case that the resin composition is used as two, three or more layer
laminates with the other thermoplastic resins, for example, polypropylene
polyethylene, polyethylene terephthalate, polyamide, polystyrene, etc.,
forming is effected by known methods such as a multilayered co-extrusion
method, a co-injection extrusion method, a coating method, etc. Further,
where there are three or more layers, it is preferred that the composition
of the present invention be used as an intermediate layer.
Further embodiments of the present invention will be described below.
As described hereinabove, for optimum gas barrier properties, the blend of
EVOH and the polyether component-containing EVOH copolymer are preferably
used, as will be noted from Examples 1-1 to 1-15. A laminate having
excellent flexural fatigue resistance, excellent gas barrier properties
and freedom form cracks or unevenness in drawing upon thermoforming (for
example, upon deep drawing, drawing, blowing), can be obtained by
providing an EVOH layer containing the polyether component. Laminates
comprising a layer of a block copolymer which is the polyether
component-containing EVOH copolymer, are shown in Examples 2-1 to 2-6. In
this case, a weight ratio of the EVOH component to the polyether component
in the block copolymer is 50 to 98 wt% of the EVOH component and 2 to 50
wt% of the polyether component. To impart flexibility thereto, the
polyether component is at least 2 wt%, preferably 5 wt% or more. On the
other hand, it is desirable that the polyether component is 50 wt% or
less, preferably 30 wt% or less, to obtain excellent gas barrier
properties. Further, MI of this block copolymer is 0.1 to 50 g/10 mins.,
preferably 0.3 to 25 g/10 mins.
In this block copolymer, Young's modulus is reduced to 2/3 to 1/10 that of
ordinary EVOH, which is flexible and melt formable as in ordinary EVOH.
The thermoplastic resins that can be used for laminating on this block
copolymer, there are included polypropylene, polyethylene (branched or
linear), ethylene-propylene copolymer, ethylene-vinyl acetate copolymer,
thermoplastic polyester, polyamide, polystyrene, polycarbonate, polyvinyl
chloride, etc. Among them, particularly preferred are linear polyethylene,
polypropylene, ethylene-propylene copolymer, thermoplastic polyester and
polystyrene.
To make laminates, the foregoing resins can be formed into a multilayered
structure of two layers, three layers or more layers. In the case of three
or more layers, the block copolymer layer is often used as an intermediate
layer.
Methods for molding or forming to obtain such laminates, known methods can
be used such as a co-extrusion method, a co-injection method, an extrusion
lamination method, a coating method, etc. Particularly preferred is the
co-extrusion method.
When preparing laminates, it is advantageous to insert an adhesive resin
between respective layers. There is no particular limitation to the
adhesive resin, but preferred examples include carboxyl-modified products
of polyethylene, ethylene-vinyl acetate copolymer, polypropylene and
ethylene-acrylic acid ester (methyl ester or ethyl ester, etc,) copolymer,
etc. A product modified with maleic anhydride may be suitably used as such
or in the form of blend with an unmodified polymer.
The thus formed laminates using the block copolymer are extremely useful as
flexible laminate packaging materials because they exhibit extremely
excellent properties in violent vibrations occurring during
transportation, flexural fatigue, impact when dropped, fatigue caused by
friction, etc. because of improved flexibility in the block copolymer
layer, as compared to laminates obtained using conventional EVOH. These
properties are more readily observed at low temperature.
Next, laminates bearing a layer of EVOH-type copolymer in which polyether
is added in a grafted form as a branch polymer of EVOH or EVOH-type
copolymer in which EVOH is added in a grafted form as a branch polymer of
polyether (hereafter they are referred to as graft copolymers) are
described in Examples 3-1 to 3-6. With respect to a weight ratio of the
EVOH component to the polyether component in the graft copolymer, the
polyether component is 2 to 60 wt%; the polyether component is at least 2
wt%, preferably 5 wt% or more from a viewpoint of imparting flexibility
thereto and on the other hand, in view of gas barrier properties, the
polyether component is at most 60 wt%, preferably 50 wt% or less. In this
case the ethylene content is preferably 31 to 60 mol%.
In the graft copolymer, Young's modulus is reduced to 2/3 to 1/10 and
impact strength becomes 2 to 50 times that of ordinary EVOH. The graft
copolymer is flexible and excellent in impact resistance and is melt
formable as in ordinary EVOH. As thermoplastic resins used for laminating
with the graft copolymer, there can be used those as described above.
The thus formed laminates using the graft copolymer are extremely useful as
flexible laminate packaging materials because they exhibit extremely
excellent properties in violent vibrations occurring during
transportation, flexural fatigue, impact when dropped, fatigue caused by
friction, etc. because of improved flexibility in the EVOH layer, as
compared to laminates obtained using conventional EVOH. These properties
can be better observed at low temperatures.
Next, still another embodiment of the present invention will be described
below.
The block copolymer used in the present invention in which the polyether
component is added at the end of EVOH is novel.
As is also evident from the foregoing description, the block copolymer is
melt formable, has good laminate formability with other thermoplastic
resins and is excellent in flexibility, flexural fatigue resistance and
gas barrier properties and therefore, is extremely useful as various
packaging materials, especially as packaging materials for foodstuffs.
Properties of the block copolymer are fully described in Examples 1-1 to
1-6 and 2-1 to 2-6 and clear from the description. Examples 1-1 to 1-3
In a reactor of a 1 liter volume equipped with a stirrer were charged 500 g
of polyoxypropylene allyl ether (manufactured by Nippon Oils and Fats Co.,
Ltd., Unisafe PKA-5018) having a molecular weight of 3000 and containing
polymerizable double bonds at both ends thereof and 4 mg of benzoyl
peroxide. While stirring at room temperature, thioacetic acid was
continuously added to the mixture at a rate of 13 g/hour for 3 hours. Then
the unreacted thioacetic acid was removed out of the reaction system at
30.degree. to 45.degree. C. under reduced pressure. Next, 100 g of
methanol and 1.1 g of sodium hydroxide were added to the system. After
stirring at 60.degree. C. for 2 hours in a nitrogen flow, acetic acid was
added to the system to neutralize an excess of sodium hydroxide. Titration
of mercapto groups of the thus obtained mercapto-polyoxypropylene with
I.sub.2 showed 6.56.times.10.sup.-4 eq/g, wherein the both ends
containing double bonds were almost quantitatively changed to mercapto
groups.
Next, 14.5 kg of vinyl acetate and 31 g of mercapto-polyoxypropylene were
charged in a polymerization tank of a 50 liter volume having a cooling
coil inside, equipped with a stirred. After the air in the polymerization
tank was replaced with nitrogen, the temperature was raised to 60.degree.
C. and ethylene was charged to render the pressure 43 kg/cm.sup.2. Then,
14 g of polymerization initiator 2,2'-azobis-(2,4-dimethylvaleronitrile)
was dissolved in 300 ml of methanol and the solution was added to the
reaction system. Subsequently, mercapto-polyoxypropylene was added to the
system at a rate of 440 g/hour for 4 hours to perform polymerization. A
conversion of the vinyl acetate was 42%. Then, the copolymerization
reaction solution was supplied to a stripping tower. After the unreacted
vinyl acetate was removed from the top by feeding methanol from the bottom
of the tower, saponification was performed using sodium hydroxide as a
catalyst in a conventional manner. Then after thoroughly washing with
acetone and then with water, the product was immersed in a diluted aqueous
acetic acid solution and the system was dried at 60.degree. to 105.degree.
C. in a nitrogen flow. The thus obtained EVOH copolymer was a block
copolymer wherein EVOH was added to the both ends of polyoxypropylene. As
a result of 500 MHZ.sup.1 N-NMR analysis, the composition had an ethylene
content of 30.8% and a polyoxypropylene content of 31 wt%, and a
sponification degree of the vinyl acetate component showed 99.1%. Further
melt index (hereafter referred to as MI) measured at 190 g under a load of
2160 g according to ASTM D-1238-65T was 120 g/10 mins.
To confirm that thus obtained EVOH copolymer is a block copolymer wherein
EVOH is added to the both ends of polyoxypropylene, that is,
EVOH-S-polyoxypropylene-S-EVOH, the EVOH block copolymer was reacetylated,
and then observed with 500 MHZ .sup.1 H-NMR. The NMR spectrum of thus
obtained reacetylated product is shown in FIG. 1.
As the peak centered at 2.6 ppm is assigned to the methylene protons
adjacement to sulfur, it is clear that this reacetylated product is a
block copolymer wherein ethylene-vinyl acetate copolymer is added to the
both ends of polyoxypropylene. Therefore, it is also clear that the
aforesaid EVOH copolymer is a block copolymer wherein EVOH is added to the
both ends of polyoxypropylene.
Next, the block copolymer (copolymer A) and EVOH having the ethylene
content of 32.1 mol%, the saponification degree in the vinyl acetate
component of 99.5% and MI of 0.61 g/10 mins. (EVOH No. 1) were blended in
various proportions. The blends were extrusion molded to give films and,
Young's modulus, flexural fatique resistance and the oxygen permeability
of the films were measured.
Using a film-forming machine equipped with an extruder and a T-die,
extrusion molding was carried out at 180.degree. to 220.degree. C.
temperature of the extruder and 215.degree. C. temperature of the T-die to
give films each having a thickness of 15.mu..
The Young's modulus was measured using as specimens films which had been
moisture controlled for 7 days under conditions of 20.degree. C. and 65%
RH, by Autograph at a extension rate of 200%/mins., according to ASTM
D-638.
The test of flexural fatique resistance was carried out using Gelbo Flex
Tester (manufactured by Rigaku Kogyo Co., Ltd.), on a specimen of 12 in.
by 8 in. made round into a cylinder having a diameter of 31/2 in. in which
both the ends were held of the stroke at an initial holding distance of 7
in. and a holding distance when flexed to the maximum of 1 in. To the
specimen were applied repeated, reciprocating motions, one motion
consisting of twisting at an angle of 440.degree. in the first 31/2 in. of
the stroke and at subsequent 21/2 in. linear horizontal motion at a rate
of 40 times/min under conditions of 20.degree. C. and 65% RH.
The measurement of the amount of gas permeation was performed after
moisture control for 7 days under conditions of 20.degree. C. and 65% RH
as well as 20.degree. C. and 85% RH, using OX-TRAN 100 manufactured by
Modern Control Co., Ltd. The specimens provided for the measurement were
those used for the test of flexural fatique resistance by changing the
reciprocating motions to various times.
The results of these measurements are shown in Tables 1-1 and 1-2.
COMPARATIVE EXAMPLES 1-1 TO 1-2
Evaluation was also made using the aforesaid EVOH alone having and ethylene
content of 32.1 mol%, a saponification degree of 99.5% in the vinyl
acetate component and MI of 0.61 g/10 mins. (EVOH No. 1) (Comparative
Example 1-1) and using the aforesaid EVOH alone having an ethylene content
of 31.5 mol% and a saponification degree of 99.6% in the vinyl acetate
component (EVOH No. 2) (Comparative Example 1-2) in a conventional manner,
in place of the resin compositions of Examples 1-1 to 1-3. The results are
shown in Tables 1-1 and 1-2.
TABLE 1-1
______________________________________
Resin Composition Young's
Copolymer A/
MI Modulus
EVOH No. 1 (g/10 mins.)
(kg/mm.sup.2)
______________________________________
Example 1-1
10/90 1.0 187
Example 1-2
20/80 1.7 163
Example 1-3
30/70 2.9 139
Comparative
EVOH No. 1 alone
0.61 215
Example 1-1
Comparative
EVOH No. 2 alone
2.5 220
Example 1-2
______________________________________
TABLE 1-2
______________________________________
Number of
Reciprocating Motion (time)
0 50 100 200
______________________________________
Example Number of Pinholes (/96 in.sup.2)
0 0 0 1
1-1 Amount of Oxygen Permeated
(c.c.20 .mu./m.sup.2 .multidot. day .multidot. atm)
20.degree. C., 65% RH
0.6 0.6 0.7 .infin.
20.degree. C., 85% RH
1.8 1.8 2.0 .infin.
Example Number of Pinholes (/96 in.sup.2)
0 0 0 0
1-2 Amount of Oxygen Permeated
(c.c.20 .mu./m.sup.2 .multidot. day .multidot. atm)
20.degree. C., 65% RH
0.7 0.7 0.7 0.8
20.degree. C., 85% RH
2.2 2.2 2.3 2.3
Example Number of Pinholes (/96 in.sup.2)
0 0 0 0
1-3 Amount of Oxygen Permeated
(c.c.20 .mu./m.sup.2 .multidot. day .multidot. atm)
20.degree. C., 65% RH
0.8 0.8 0.8 0.9
20.degree. C., 85% RH
2.7 2.7 2.7 2.9
Compara-
Number of Pinholes (/96 in.sup.2)
0 1 14 26
tive Ex-
Amount of Oxygen Permeated
ample 1-1
(c.c.20 .mu./m.sup.2 .multidot. day .multidot. atm)
20.degree. C., 65% RH
0.5 .infin.
.infin.
28
20.degree. C., 85% RH
1.5 .infin.
.infin.
.infin.
Compara-
Number of Pinholes (/96 in.sup.2)
0 1 16 31
tive Ex-
Amount of Oxygen Permeated
ample 1-2
(c.c.20 .mu./m.sup.2 .multidot. day .multidot. atm)
20.degree. C., 65% RH
0.5 .infin.
.infin.
28
20.degree. C., 85% RH
1.4 .infin.
.infin.
.infin.
______________________________________
Note:
.infin. indicates that there is no oxygen barrier properties.
EXAMPLES 1-4 TO 1-6
In a polymerization tank as shown in Examples 1-1 to 1-3 were charged 25.0
kg of vinyl acetate and 3.9 g of thioacetic acid. After the air in the
polymerization tank was replaced with nitrogen, the temperature was raised
to 60.degree. C. and ethylene was charged to render the pressure 60
kg/cm.sup.2. Then, 100 g of polymerization initiator
2,2'-azobis-isobutyronitrile was dissolved in 1 liter of methanol and the
solution was added to the reaction system. Subsequently, methanol solution
of 11.7 g/l thioacetic acid was added to the system at a rate of 500
ml/hour for 8 hours for polymerization. The conversion of the vinyl
acetate was 40%. Then, the copolymerization reaction solution was supplied
to a stripping tower. After the unreacted vinyl acetate was removed from
the top by feeding methanol from the bottom of the tower, saponification
was performed using sodium hydroxide as a catalyst in a conventional
manner. Then after thoroughly washing with water and then with acetone,
the product was dried at 40.degree. C. under reduced pressure.
Next, 6.0 kg of EVOH containing mercapto groups at the ends thereof
obtained in the method described above, 2.5 kg of polyoxypropylene allyl
ether (manufactured by Nippon Oils and Fats Co., Ltd., Unisafe PKA-5014)
having a molecular weight of 1500 and containing a polymerizable double
bond at one end thereof and 20 kg of dimethylsulfoxide were charged in the
polymerization tank described above. After the air in the polymerization
tank was replaced with nitrogen, the temperature was raised to 60.degree.
C. to obtain a homogeneous solution. Then 500 ml of a 100 g/l methanol
solution of 2,2'-azobisisobutyronitrile was added to the system followed
by reaction for 5 hours. Next, the reaction solution was added to 200
liters of acetone in small portions with stirring to precipitate the EVOH
copolymer. After thoroughly washing with acetone, the product was immersed
in a diluted aqueous acetic acid solution and the system was dried at
60.degree. to 105.degree. C. in a nitrogen flow. The thus obtained EVOH
copolymer was a block copolymer wherein polyoxypropylene was added to one
end of EVOH.
Employing NMR analysis, it was determined that the composition had an
ethylene content of 44.2 mol% and a polyoxypropylene content of 24 wt%,
and the saponification degree of the vinyl acetate component showed 99.4%.
Further MI was 230 g/10 mins.
Next, the copolymer (copolymer B) and EVOH having the ethylene content of
45.1 mol%, a saponification degree in the vinyl acetate component of 99.5%
and MI of 2.8 g/10 mins. (EVOH No. 2) were blended in various proportions.
The blends were extrusion molded in a manner similar to Examples 1-1 to
1-3 to give films and, Young's modulus, flexural fatigue resistance and
oxygen permeability of the films were measured. The results are shown in
Tables 1-3 and 1-4.
COMPARATIVE EXAMPLES 1-3 TO 1-4
Evaluation was also made using the aforesaid EVOH alone having an ethylene
content of 45.1 mol%, a saponification degree of 99.5% in the vinyl
acetate component and MI of 2.8 g/10 mins. (EVOH No. 3) (Comparative
Example 1-3) and using the aforesaid EVOH alone having an ethylene content
of 44.3 mol%, a saponification degree of 99.3% in the vinyl acetate
component and MI of 9.5 g/10 mins. (EVOH No. 4) (Comparative Example 1-4),
in place of the resin compositions of Examples 1-4 to 1-6. The results are
shown in Tables 1-3 and 1-4.
TABLE 1-3
______________________________________
Resin Composition Young's
Copolymer B/
MI Modulus
EVOH No. 2 (g/10 mins.)
(kg/mm.sup.2)
______________________________________
Example 10/90 4.4 130
1-4
Example 20/80 6.8 101
1-5
Example 30/70 10.5 72
1-6
Comparative
EVOH No. 3 alone
2.8 151
Example 1-3
Comparative
EVOH No. 4 alone
9.5 148
Example 1-4
______________________________________
TABLE 1-4
______________________________________
Number of
Reciprocating Motion (time)
0 70 150 250
______________________________________
Example Number of Pinholes (/96 in.sup.2)
0 0 0 1
1-4 Amount of Oxygen Permeated
(c.c.20 .mu./m.sup.2 .multidot. day .multidot. atm)
20.degree. C., 65% RH
1.5 1.5 1.8 .infin.
20.degree. C., 85% RH
3.8 3.8 4.2 .infin.
Example Number of Pinholes (/96 in.sup.2)
0 0 0 0
1-5 Amount of Oxygen Permeated
(c.c.20 .mu./m.sup.2 .multidot. day .multidot. atm)
20.degree. C., 65% RH
1.8 1.8 2.1 2.5
20.degree. C., 85% RH
4.5 4.6 4.9 5.5
Example Number of Pinholes (/96 in.sup.2)
0 0 0 0
1-6 Amount of Oxygen Permeated
(c.c.20 .mu./m.sup.2 .multidot. day .multidot. atm)
20.degree. C., 65% RH
2.2 2.3 2.5 2.8
20.degree. C., 85% RH
5.5 5.7 5.9 6.2
Compara-
Number of Pinholes (/96 in.sup.2)
0 1 17 29
tive Ex-
Amount of Oxygen Permeated
ample 1-3
(c.c.20 .mu./m.sup.2 .multidot. day .multidot. atm)
20.degree. C., 65% RH
1.3 .infin.
.infin.
.infin.
20.degree. C., 85% RH
3.3 .infin.
.infin.
.infin.
Compara-
Number of Pinholes (/96 in.sup.2)
0 2 25 38
tive Ex-
Amount of Oxygen Permeated
ample 1-4
(c.c. 20 .mu./m.sup.2 .multidot. day .multidot. atm)
20.degree. C., 65% RH
1.2 .infin.
.infin.
.infin.
20.degree. C., 85% RH
3.1 .infin.
.infin.
.infin.
______________________________________
Note:
.infin. indicates that there is no oxygen barrier properties.
EXAMPLES 1-7 TO 1-9
In a polymerization tank as in Examples 1-1 to 1-3 was charged a solution
of 11.0 kg of vinyl acetate, 7.46 kg of polyoxypropylene allyl ether
(manufactured by Nippon Oils and Fats Co., Ltd., Unisafe PKA-5018) having
a molecular weight of 3000 and containing polymerizable double bonds at
both ends thereof, 4.7 kg of methanol and 45 g of
2,2'-azobis-(2,4-dimethylvaleronitrile) dissolved in 500 ml of methanol
and the ethylene pressure was rendered 37 kg/cm.sup.2. Copolymerization
was conducted at 60.degree. C. for 6.8 hours. The conversion of the vinyl
acetate was 40%. Then, the copolymerization reaction solution was supplied
to a stripping tower. After the unreacted vinyl acetate was removed from
the top by feeding methanol from the bottom of the tower, saponification
was performed using sodium hydroxide as a catalyst in a conventional
manner. Then after thoroughly washing with acetone and then with water,
the product was immersed in a diluted aqueous acetic acid solution and the
system was dried at 60.degree. to 105.degree. C. in a nitrogen flow. In
the thus obtained EVOH copolymer, polyoxypropylene was added in a grafted
form as a branch polymer of EVOH. Employing NMR analysis, it was
determined that the composition had an ethylene content of 37.6 mol% and a
polyoxypropylene content of 49 wt%, and the saponification degree of the
vinyl acetate component showed 99.4%. Further MI was 0.51 g/10 mins.
Next, the copolymer (copolymer C) and EVOH having the ethylene content of
37.8 mol%, the saponification degree in the vinyl acetate component of
99.4% and MI of 1.3 g/10 mins. (EVOH No. 5) were blended in various
proportions. The blends were formed into films in a manner similar to
Examples 1-1 to 1-3 to give films having a thickness of 15.mu.. Young's
modulus, flexural fatigue resistance and oxygen permeation of the films
were measured. The results are shown in Tables 1-5 and 1-6.
COMPARATIVE EXAMPLE 1-5
Evaluation was also made using the aforesaid EVOH alone having the ethylene
content of 37.8 mol%, the saponification degree of 99.4% in the vinyl
acetate component and MI of 1.3 g/10 mins. (EVOH No. 5), in place of the
resin compositions of Examples 1-7 to 1-9. The results are shown in Tables
1-5 and 1-6.
TABLE 1-5
______________________________________
Resin Composition Young's
Copolymer C/
MI Modulus
EVOH No. 5 (g/10 mins.)
(kg/mm.sup.2)
______________________________________
Example 1-7
10/90 1.2 146
Example 1-8
20/80 1.1 123
Example 1-9
30/70 1.0 99
Comparative
EVOH No. 5 alone
1.3 183
Example 1-5
______________________________________
TABLE 1-6
______________________________________
Number of
Reciprocating Motion (time)
0 60 100 200
______________________________________
Example Number of Pinholes (/96 in.sup.2)
0 0 0 1
1-7 Amount of Oxygen Permeated
(c.c.20 .mu./m.sup.2 .multidot. day .multidot. atm)
20.degree. C., 65% RH
1.0 1.0 1.3 .infin.
20.degree. C., 85% RH
3.1 3.1 3.6 .infin.
Example Number of Pinholes (/96 in.sup.2)
0 0 0 0
1-8 Amount of Oxygen Permeated
(c.c.20 .mu./m.sup.2 .multidot. day .multidot. atm)
20.degree. C., 65% RH
1.2 1.2 1.3 1.5
20.degree. C., 85% RH
3.8 3.8 4.0 4.6
Example Number of Pinholes (/96 in.sup.2)
0 0 0 0
1-9 Amount of Oxygen Permeated
(c.c.20 .mu./m.sup.2 .multidot. day .multidot. atm)
20.degree. C., 65% RH
1.5 1.5 1.7 2.0
20.degree. C., 85% RH
4.8 4.8 5.0 5.5
Compara-
Number of Pinholes (/96 in.sup.2)
0 1 21 29
tive Ex-
Amount of Oxygen Permeated
ample 1-5
(c.c.20 .mu./m.sup.2 .multidot. day .multidot. atm)
20.degree. C., 65% RH
0.8 .infin.
.infin.
.infin.
20.degree. C., 85% RH
2.5 .infin.
.infin.
.infin.
______________________________________
Note:
.infin. indicates that there is no oxygen barrier properties.
EXAMPLES 1-10 TO 1-12
In a reactor of a 10 liter volume equipped with a stirrer were charged 4.5
kg of thoroughly dehydrated poly(oxyethylene-oxypropylene) (manufactured
by Nippon Oils and Fats Co., Ltd., Unirub DE-60) having a molecular weight
of 3000, 480 g of methylenebis(4-phenylisocyanate), 64 g of thioglycerol
and 36 g of acetic acid. Stirring was continued at 80.degree. C. for 3
hours to synthesize polyether containing mercapto group at the side chain
thereof.
Next, 14.5 kg of vinyl acetate and 55 g of the aforesaid polyether
containing thiol group at the side chain thereof were charged in a
polymerization tank as in Examples 1-1 to 1-3. After the air in the
polymerization tank was replaced with nitrogen, the temperature was raised
to 60.degree. C. and ethylene was charged to render the pressure 43
kg/cm.sup.2. Then, 14 g of polymerization initiator
2,2'-azobis-(2,4-dimethylvaleronitrile) was added to the system;
thereafter, the polyether containing thiol groups at the side chain
thereof was added at a rate of 404 g/hour for 5 hours to effect
polymerization. The conversion of the vinyl acetate was 39%. Then, the
copolymerization reaction solution was supplied to a stripping tower.
After the unreacted vinyl acetate was removed from the top by feeding
methanol from the bottom of the tower, saponification was performed using
sodium hydroxide as a catalyst in a conventional manner. Then after
thoroughly washing with acetone and then with water, the product was
immersed in a diluted aqueous acetic acid solution and the system was
dried at 60.degree. to 105.degree. C. in a nitrogen flow. In the thus
obtained EVOH copolymer EVOH was added in a grafted form as a branch
polymer of polyether. Employing NMR analysis it was determined that, the
composition had an ethylene content of 31.8 mol% and a
poly(oxyethylene-oxypropylene) content of 35 wt%, and the saponification
degree of the vinyl acetate component showed 99.3%. Further MI was 170
g/10 mins.
Next, the copolymer (copolymer D) and EVOH having the ethylene content of
32.1 mol%, the saponification degree in the vinyl acetate component of
99.5% and MI of 0.61 g/10 mins. (EVOH No. 1) used in Examples | | |
