Note: Descriptions are shown in the official language in which they were submitted.
~036779
This invention relates to a biaxially stretched film consisting
essentially of a l~ighly polymerized polyester at least 90 mol% of the re-
curring units of which are composed of ethylene 2,6-naphtl~alate units, such
polyester having a carboxyl group content of not more tl~an 30 cquivalents/
tOII, The invention also relates to a thermally sta~le material, especially
an electrically insulatin~ material, consisting essentially of the above
biaxially stretched film.
It has already been known that films composed of polyethylene
2,6-naphthalate (to be referred to as PEN) have superior heat-resistant pro-
perties, and are suited, for example, for use as an electrically insulating
material (see, for example, Belgian Patent No. 777,126).
We have now found that as compared with the known biaxiallyoriented films of ethylene 2,6-naphthalate polyester, biaxially oriented
films composed of ethylene 2,6-naphthalate polyesters having a low carboxyl
group content, especially a carboxyl group content not exceeding 30 equiva-
lents/ton have very superior heat~resistant properties, for example, resis-
tance to wet heat, resistance to dry heat, and resistance to oils or cooling
media at an elevated temperature of, for example 80C. or above, and retain
their superior properties even when allowed to stand for long periods of
time in the wet state, in the dry state, or in oils or in an atmosphere of
cooling media at an elevated temperatureO
The term "ethylene 2,6-naphthalate polyester", as used in the
present specification and the appended claims, denotes not only a polyester
100 mol% of which recurring units are composed of ethylene 2,6-naphthalate
~i.e., polyethylene 2,6-naphthalate or PEN), but also a copolyester wherein
not more than 10 mol%, preferably not more than 5 mol%, of the total recur-
ring units are composed of a comonomer or modifier other than the ethylene
2,6-naphthalate, and a mixture of at least 90 mol%, preferabl~ at least 95
mol%, of PEN and not more than 10 mol%, preferably not more than 5 mol%, of
- 1 - ~
another polyester. lV~9
In general, the polyethylene 2,6 naphthalate is prepared by reac-
ting naphthalene-2,6^dicarboxylic acid or its functional derivative or deri-
vatives ~ith ethylene glycol or its functional derivative or derivatives in
the presence of a catalyst or catalysts. The reaction conditions and opera-
ting procedures have been known in the art, and are disclosed, for example,
in British Patent No. ~04,073 and United States Patent No. 3,161,710. When
the copolyesters are to be prepared, one or more suitable comonomers or
modifiers are added to the polymerization system before the completion of the
reaction of forming the polyethylene 2,6-naphthalate, and then the polymeriz-
ation is continued until the copolyestersare formed.
The comonomer or modifier may be a compound or compounds having a
divalent ester-forming functional groupO Examples of this compound are
dicarboxylic acids such as oxalic acid, adipic acid, phthalic acid, isophthalic
acid, terephthalic acid, naphthalene-1,5-dicarboxylic acid, naphthalene-1,6-
dicarboxylic acid, naphthalene-2,7-dicarboxylic acid, 4,4-diphenoxyethane
dicarboxylic acid, succinic acid, diphenyl ether dicarboxylic acid and lower
alkyl esters of these dicarboxylic acids; hydroxycarboxylic acids such as
E~hydroxybenzoic acid and ~-hydroxyethoxybenzoic acid, and lower alkyl esters
of these hydroxycarboxylic acids; and dihydric alcohols such as trimethylene
glycol, tetramethylene glycol, hexamethylene glycol, or neopentyl glycol.
The polyethylene 2,6-naphthalate or its modified product may have terminal
hydroxyl and/or carboxyl groups capped with a monofunctional compound or
compounds such as benzoic acid, benzoyl benzoic acid, benzyloxybenzoic acid
or methoxypolyalkylene glycols. There can also be used polyethylene 2,6-
naphthalate polyesters modified with a very small amount of a polyfunctional
compound or compounds such as glycerol and pentaerythritol to such an extent
that the linearity of the polymer is not substantially lost.
The other polyesters used to form the PEN mixtures are, for
~3~77~
example, those derived from a dicarboxylic acid component selected from
terephthalic acid, isophthalic acid, adipic acid, succinic acid, naphthalene-
2,6-dicarboxylic acid, naphthalene-1,5-dicarboxylic acid, 4,4-diphenoxyethane
dicarboxylic acid, 4,4'-tetramethylene diphenyl dicarboxylic acid, and
functional derivatives thereof and a glycol component selected from ethylene
glycol, trimethylene ~lycol, tetramethylene glycol, hexamethylene glycol,
neopentyl glycol, and functional derivatives thereof. The functional deri-
vatives may, for example, be lower alkyl esters of the carboxylic acids, as
exemplified ~Yith respect to the polyethylene 2~6-naphthalate.
The ethylene 2~6-naphthalate polyester for making the biaxially
stretched film of this invention should have
(1) an intrinsic viscosity [n], calculated from the value
measured in o-chlorophenol at 35C., of at least 0.40, preferably at least
0.45, (100 cc/g), and
(2) a carboxyl group content of not more than 30 equivalents/ton,
preferably not more than 25 equivalents/ton.
Those having a lower intrinsic viscosity than that specified above
have too low degrees of polymerization, and reduced mechanical properties,
and are naturally not preferred for use in the present invention.
So long as the polyester meets the above requirements (1) and (2),
it may contain a delusterant such as titanium dioxide, a stabilizer or
stabilizers such as phosphoric acid, phosphorous acid or an ester of any of
these, a lubricant or lubricants such as finely divided silica or china clay,
or other fillers.
The biaxially stretched film of this invention is characterized by
being composed of the ethylene 2,6-naphthalate polyester having a low
carboxyl group content. The carboxyl group content of the polyester can be
measured by the method of A. Conix disclosed in Die Makromolekulare Chemie,
Vol. 26, pages 226 et seq. (1958). Briefly stated, this method comprises
--3--
i779 f.
dissolving the polyester in hot benzyl alcohol in an inert gas atmosphere,
and titrating it with sodium hydroxide using Phenol Red. Therefore, the
equivalents/ton of the polyester represent the equivalents of sodium
hydroxide required to titrate every 106 grams (one ton) of the polymer.
This sho~s the concentration of the free carboxyl group present in the
polyester.
The biaxially stretched film of this invention can be produced by
forming a film of an ethylene 2,6-naphthalate polyester having a high degree
of polymerization and a low carboxyl group content which fully meets the
requirements of intrinsic viscosity (l) and carboxyl group content (2)
described above, biaxially stretching the resulting polyester film, and if
desired, further heat-treating the stretched film.
The conventional method for producing polyesters as mentioned
above is not preferred for forming polyesters having such a high degree of
polymerization and a low carboxyl group content, because such a conventional
method generally requires high temperatures and relatively long periods of
time in order to obtain highly polymerized polyesters. The polymerization
reaction at high temperatures for a long period of time can result in an
increase in the degrees of polymerization of the resulting polyester, but on
the other hand, tends to cause an increase in the amount of the carboxyl end
groups of the polyester.
Accordingly, in order to produce ethylene 2,6-naphthalate polyes-
ters having a high degree of polymerization and a low carboxyl group content
which are suitable for use in preparing the biaxially stretched films of
this invention, the followirg methods are recommended.
For example, the polyester used in this invention can be prepared
by the melt-polymerization process disclosed, for example, in United States
Patents Nos. 3,433,770, 3,637,910, 3,714,125 and 3,787,370 in which a com-
pound such as diphenyl carbonate or diphenyl oxalate is added to the
--4--
1036779
polyester-forming reaction system described above. Alternatively, polyesters
having a high degrees of polymerization and a relatively low carboxyl group
content, as used in the present invention,can be synthesized by forming PEN
having a medium degree of polymerization by the melt-polymerization process,
and then polymerizing the PEN in the solid state.
In this case too, a compound such as diphenyl carbonate or di-
phenyl oxalate is preferably added to the polyester-forming reaction system
in the molten state or the solid state.
Furthermore, ethylene 2,6-naphthalate polyesters prepared by
methods known per sie may be treated~ in the form of chips or films, with an
epoxy compound such as epoxidized glycerol or vinyl cyclohexene dioxide, or
diazomethane, thereby to reduce the carboxyl group content of the polyesters
to the values specified in the present invention.
In short, so long as the intrinsic viscosity and carboxyl group
content as defined in this invention are completely satisfied, any ethylene
2,6-naphthalate polyesters can be used irrespective of the method of
preparation.
The polyesters can be fabricated into biaxially oriented films by
any desired method, but some preferred embodiments are cited below.
For example, the biaxially stretched film of this invention can be
obtained by first preparing an unstretched film by drying the polyester at a
temperature of 140C. to 220C., and then melt-extruding the dried polyester
at a temperature of 280C. to 330C., preferably 285C. to 315C. The resul-
ting unstretched film is stretched in the longitudinal direction at a ratio
of about 3 to 5, preferably 3 to 4 at a temperature of about 120C. to
160C., preferably 135C. to 160C., and then in the transverse direction at
ratio of about 3 to 5, preferably about 3 to 4, at a temperature of about
115C. to 150C., preferably 120C. to 140C., and then if desired, heat-
treating the stretched film at a temperature of about 170C. to 240C.
--5--
10367~9
Alternatively, an unstretched tubular film of the polyester is
stretched at a temperature of 125C. to 160C., preferably 130C. to 150C.
both in the longitudinal direction at a ratio of about 2.5 to about 5 and in
the direction of the diameter of the tube at a ratio of about 2.5 to about 5,
and then, if desired, the stretched film is heat-treated at a temperature of
170C. to 240C., thereby to obtain the biaxially stretched film of this
invention.
The biaxially stretched film of this invention can be a '`shrink-
able~ film if in the above-described procedures, the film is not heat-set
after the stretching, or it is heat-set at a temperature above the stretching
temperature but below 170C. after the stretching.
Depending upon the conditions described above, the film of this
invention can ei~her be a thermally stable film or a shrinkable film. How-
ever, irrespective of whether it is shrinkable or not, the film of this
invention retains the superior properties for prolonged periods of time when
exposed to heat in the dry or wet state, or to elevated temperatures in the
presence of a cooling medium or oil, as will be described below.
As stated above, it is important that in the preparation of the
biaxially stretched f;l~ of this invention, the ethylene 2,6-naphthalate
p`Dlyester should be used which has an intrinsic viscosity, as defined
hereinabove, of at least 0.40, preferably at least 0.45, and a carboxyl
group content of not more than 30 equivalents/ton, preferably not more than
25 equivalents/ton.
In order to prevent the intrinsic viscosity from decreasing and/or
the carboxyl group content from increasing, during the preparation of the
unstretched film and/or during the heat-treatment of the stretched film, it
is preferred to employ one or more of the following conditions.
(a) The starting polyester should be dried as sufficiently as
possible.
--6--
1036779
(b) In the preparation of an unstretched film of the polyester,
the melting and extrudirg temperatures of the polyester should be kept as
low as possible.
(c) The extrusion of the polymer shou~l be carried out in an inert
gas atmosphere, for example, a nitrogen gas.
(d) The residence time of the polyester in the molten state should
be sh~rtened as much as possible.
By employing these conditions, it is possible to prepare a
biaxially stretched film composed of the polyester having the intrinsic
viscosity and the carboxyl group content as specified above.
The biaxially stretched films of this invention which have the high
degrees of polymerization and low carboxyl group content as defined above
retain superior properties, for example, high tensile strength and high
elongation at break, as compared with biaxially oriented films composed of
ethylene 2, & naphthalate polyesters having a carboxyl group content exceeding
the upper limit specified in the present invention, when the films are sub-
jected to the following conditions.
(i) When maintained in an atmosphere having a high moisture
content and held at an elevated temperature (a wet heat atmosphere).
(ii) When maintained in a dry atmosphere held at an elevated
temperature (a dry heat atmosphere).
(iii) When maintained in an atmosphere held at an elevated
temperature in which a cooling medium gas such as a fluorohydrocarbon or
fluorochlorohydrocarbon is present (an atmosphere of a cooling medium held
at an elevated temperature).
(iv) When maintained in an atmosphere held at an elevated temper-
ature in which an oil such as a lubricating oil, machine oil, or insulating
oil is present (an atmosphere of an oil held at a high temperature).
Accordingly, the biaxially stretched films of this invention are
--7--
1036~79
superior as thermally stable materials, and find utility as decorative and
other industrial materials which are to be subjected to coating, metallizing
or other treatments at high temperatures.
In addition to these superior properties, the biaxially stretched
films of this invention have high dielectric strergth, and therefore, are
suitab`1e as insulating materials for electric appliances which are likely to
come into contact with a cooling medium of, for example, refrigerators, or
lubricating oils, machine oils, or insulating oils.
The following examples illustrate the present invention. It
should be understood that these examples are only illustrative, and are not
in any way intended to limit the present invention.
The various properties in the examples were measured by the follow-
ing methods.
(a) Tensile Mechanical Properties
Determined at 23C. in an atmosphere having a relative humidity of
65% using an Instron-type tensile tester under the following conditions.
Sample form: strip (15 cm x 1 cm)
Chuck distance: 10 cm
Pulling rate: 10 cm/min.
(b) Moisture Content of Polyester
(1) A sample was taken out in an atmosphere of dry nitrogen.
(2) The sample was transferred to an oven of a moisture analyzer
(Bell ~ Howell 26-321) placed in a dry box.
(3) The temperature of the oven was raised to 200C., and measure-
ment was continued until there was no moisture.
(4) The sample was taken out of the oven, and was weighed by a
balance. The moisture content is defined by the following equation.
Weight of moisture
Moisture content= x 100
Welght of sample
1036779
(c) Carboxyl group content
Measured in accordance with the A. Conix's method disclosed in
"Die Makromolekulare Chemie", Vol. 26, P 226 et seq. (1918). About 100 mg
(W) of the polymer was added to 10 ml. of benzyl alcohol and dissolved at
215C. in 2.5 min. The solution was cooled to room temperature by adding
10 n~. of chloroform, and then titrated with a 0.1N benzyl alcohol solution
of sodium hydroxide. The amount titrated is designated A ml. Then, 10 ml.
of benzyl alcohol alone was taken, and titrated with a 0.1N benzyl alcohol
solution of sodium hydroxide. The amount titrated at this time is desig-
nated B ml. Then, the carboxyl group content of the sample polymer is
calculated in accordance with the following equation.
CarboXyl group =0.1 (A-B)F/W
content
(F=factor of a O.lN benzyl alcohol
solution of sodium hydroxide)
(d) A test to determine the resistance to cooling medium was performed in
the following manner.
(1) A film sample was wrapped with a stairless steel net, and
dried in vacuo at 110C. for 5 hours.
(2) The film ~as placed in a 800 ml. shakirg-type autoclave in an
atmosphere of nitrogen gas.
(3) 250 g of CHClF2 as a cooling medium (Daiflon R-22, the product
of Daikin Kogyo Kabushiki Kaisha, dried by being passed through a molecular
sieve) and 250 g of Suniso 3&S (an insulating oil of Sun Oil Company, dried
for 1 hour at 100C) were added.
(4) The temperature of the autoclave was elevated to 155C., and
the autoclave was maintained at this temperature for 18 days.
(e) Dielectric stren~th
Determined in accordance wi*n the method of JIS C 2318. An
_g_
1036779
alternate current was applied using a disc electrode with a diameter of
25 mm, and the voltage was elevated at a rate of 1 KV/sec.
(f) Retention of each of the properties
Let the value of a property of a sample before being subjected to
each of the tests mentioned above (e.g. cooling medium resistance test) be
A, and the value of the property of the sample after the test be B, then the
retention (%) can be expressed by
Retention (%)-- A 11 x 100
(g) Treatment with Diazomethane
In accordance with the method disclosed in '`Organic Synthesis"
(John Wiley ~ Sons, New York, Champman and Hall, London, edited by A. H.
Blatt), Collective Vol.2, page 165, diazomethane was produced and sufficient-
ly dissolved in ethyl ether. A sample film was immersed in the solution at
room temperature, and allowed to stand for a certain period of time, after
which the film was taken out.
Examples 1 to 3 and Controls 1 and 2
Polyethylene 2,6-naphthalate having a carboxyl group content of
35.3 equivalents/ton and an intrinsic viscosity of 0.62 and containing 0.065
mol % of trimethyl phosphite as a stabilizer was dried for 3 hours in hot air
held at 175C At this time, the polymer had a moisture content of 0.002%.
The dried polymer was melt-extruded at a temperature of 300C.. The result-
ing unstretched film was stretched at 135C. in the longitudinal direction at
a ratio of 3.5, and then at 127C. in the transverse direction at a ratio of
3.8, and then heat-set at 230C. for 12 second to form a 27~ thick stretched
film. The film was immersed in ethyl ether with diazomethane at room temp-
erature for varying periods of time thereby to form films having different
carboxyl group content.
--10--
103~
~ he c~rboxyl group content, tensile strength,
elong~tion ~t bre~k, ~nd dielectric strength of e~ch film
~re shown in ~ble 1.
1036779
= ~
. ..
~ ~ o ~ ~ o U)
~. ~ ~ ~ ~ ~ ~ ~
C~
~1 OGD~`3u)~
ao
~1 o
E~l ~ U~
C`l C`~ C~ C`l C`J
..
U~ o
~ ~ ~ .
o ~ ,o, C, o ~ ~ '
I X
~*
I! ~ ~
~036~9
It is seen from Table 1 that the films were not affected in their
tensile strength, elongation at break and dielectric strength by the diazo-
methane treatment alone.
Each of the films was then subjected to the cooling medium resis-
tance test as described hereinabove. The values and retentions of each
property after the test are shown in Table 2.
Table 2
.
Runs Tensile Elongation Dielectric
strength(Kg/cm2)at break(%) strength
(retention in (retension (K~/mm)
%) in %) (retention
_ .
Example 1 2340 78 311
(85) (98) (115)
Example 2 2320 80 304
(83) (103) (110)
Example 3 2380 73 254
(86) (89) (93)
Control 2120 57 232
1 (78) (76) (83)
Control 1860 54 234
2 (68) (70) (85)
(The values in the parentheses show the retention.)
The measurements of the tensile strength and elongation at break
were performed both in the longitudinal direction and in the transverse
direction of the films. But the above tables show the values obtained by
the measurement in the longitudinal direction, because the values in the
transverse direction were substantially the same as, or greater than, those
in the longitudinal direction.
Examples 4 to 6 and Controls 3 and 4
Polyethylene 2~6-naphthalate having a carboxyl group content of
-13-
103~779
12.1 equivalents/ton and an intrinsic viscosity of 0.62 and containing
0.1 mol% of trimethyl phosphite as a stabilizer was dried, and then melt-
extruded in a dry air atmosphere to form an unstretched film. The drying
temperature and time, and the extruding temperature were changed as shown
in Table 3.
Table 3
~uns ~ DryingDrying Moisture Extruding COOH content
temper-time content temper- of the
ature(minutes) of dried ature unstretched
(C) polymer C) film
(%) (equivalents/
Example 160300 0.0019 388 24.0
175180 0.0016 298 18.5
Example 220 60 O.OQ23 295 27.3
Control 1001800 0.0078 295 57.2
G~otrcl O. O
Each of the unstretched films was stretched first in the longi-
tudinal direction at a ratio of 3.5 at 135C., and then in the transverse
direction at a ratio of 3.8 at 127C., and then the stretched film was heat-
set at 230C. for 15 seconds to form a 2.7,u thick film. The carboxyl group
content of each of the stretched films coincided with that of the unstretched
film within the range of experimental errors.
Each of the stretched films was subjected to the cooling medium
resistance test, and the retentions of the various properties of the film
were determined. The results are shown in Table 4. The retentions of the
--1~
1036779
properties were those of the properties measured in the longitudinal direc-
tion of the films.
Table 4
. .,
Runs Retention of Retention of Retention of
tensile elongation dielectric
strength ~) at break(%) resistance (%)
_
E~cample 4 83 103 110
Example 5 85 98 115
Example 6 86 89 93
Control 3 58 68 83
Control 4 Not measureable because of marked
deterioration
E~camPles 7 and 8 and Control 5
A copolyester consisting of 96.5 mol% of ethylene naphthalate
units and 3.5 mol% of ethylene terephthalate units which had a carboxyl
group content of 37.1 equivalents/ton and an intrinsic viscosity of 0.63
and contained 0.08 mol% of phosphorous acid was fabricated into an unstretched
10 ~` film and stretched and heat-set under the same conditions as in Example 1 to
form a 23~ thick film. Each of the stretched films was then treated with
diazomethane to form stretched films of varying carboxyl group content.
Each of the films was then subjected to the cooling medium resis-
tance test, and the retention of the properties of each of the films were
determined. The results are shown in Table 5.
--15--
1036~
Table 5
-
Runs COOH Retention Retention Retention of
content of tensile of elon- dielectric
(equivalents/ strength gation at resistance
ton) break
(%) (%) (%)
_ .. __
Example 7 17.1 88 102 109
Example 8 26.3 85 97 111
Control 5 38.? 73 74 83 .
ExamPles ~ and 10
Two polymers were prepared in accordance with
the method disclosed in United States Patent No. 3,433,770
in the following manner.
An autoclave equipped with a rectifying column
was charged with 5,000 parts of 2~6-dimethyl naphthalate~
2,600 parts of ethylene glycol, 3.50 parts of calcium
acetate monohydrate and 1.80 parts of antimony trioxide,
and heated at 165 to 230C for 4 hours. After releasing
methanol formed, 0.840 parts of phosphorous acid was added.
The reaction mixture was then transferred to a polymerization
vessel, and the temperature was gradually raised, after
which the reaction mixtùre was reacted for 10 minutes at
260C. and at atmospheric pressure, and for 40 minutes at
275C. and at 20 mmHg. The polymerization was further
continued at 290C. at a reduced pressure of less than
J~
i7'~9
0.5 mmHg, and diphenyl oxalate was added in an amount of 0.8 mol%
(Example 9), and 1.2 mol% (Example 10) respectively based on the
total acid component. After the addition of the diphenyl oxalate,
the reaction was carried out for several minutes at atmospheric
pressure, and the pressure of the reaction system was gradually
reduced. Finally, the reaction was performed for 15 minutes at
a pressure of less than 0.5 mmHg to form two polymers, one having
an intrinsic viscosity of 0.69 and a carboxyl group content of
11.2 equivalents/ton (Example 9) and the other having an intrin-
sic viscosity of 0.66 and a carboxyl group content of 6.3
equivalents/ton. (Example 10).
Each of the polymers was dried for 3 hours at 175C.,
and then melt-extruded at 293C. in a dry nitrogen atmosphere.
The resulting unstretched film was stretched both in the longi-
tudinal direction and in the transverse direction and heat-set
under the same conditions as in Example 1 to form a 25~u thick
film having a low carboxyl group content.
Each of the biaxially stretched films was subjected
to the cooling medium resistance test, and the results are
shown in Table 6.
-17-
103~;77~
Table 6
Runs COOH Retention Retention I ~etention .
content of of tensile of elo~ga- o~ dielect-
the film strength tion at ric
(equivalents/ break strength
ton) (~) (~ (%)
__ _ _ ._ .
Example 9 23.1 85 99 106
Examplc 10 19.2 87 I101 108 L
Exam~les 11 and 12 and Control 6
Each of polymers having different carboxyl
group content was dried at 170C. for 5 hours, and melt-
extruded at 295C. in a dry nltrogen atmosphere to form
an unstretched film. me unstretched film was stretched
at 130C. simultaneously in the longitudinal direction at
a ratio of 3.6 and in the transverse direction at a ratio of
3.6, and then heat-set under tension at 240C. for 30
scconds.
The intrinsic viscosities and carboxyl group
contents of the films are shown in T-able 7 below, Inciden-
tally, each of these films contained 0.1 mol% of trimethyl
phosphite.
/~
_,~ _
~ 0 ~ 7 7
Table 7
Runs Intrinsic Carboxyl
viscosity group con-
(~quivalents/ton)
, _ _ ~ .
Example 11 0.56 20,4
Example 12 0,58 28,0
Control 6 0,61 43,1
Each of the films was sub~ected to the following
tests,
(1) The film was wrapped with a stainless steel
net, and dried at 110C. at reduced pressure for 5 hours,
men the film was placed in a dry nitrogen atmosphere in
a 800 ml. shaking-type autoclave, Furthermore, 250g of
CHClF2 gas was added, and after sealing the autoclave, the
temperature was raised to 185C., and the film was maintained
at this temperature ~or 20 hours, me properties of the
films before and after treatment with CHClF2 gas, and the
retentions of these properties are shown in Table 8 below.
_ ~_
10367~9
Table 8
. .
~Before tr~ atment ~ reatment
Tensile Elongation Tensile Elongation
Runs strength at break strength at break
(K~/cm2) (S) tKg/cm2) (%)
. __ . .
~xample 11 2860 68 1(70) 13
¦ Examp e 12 ¦ 2730 ¦ 65 ¦ 10 0 ¦ (9 )
Control 6 2790 71 ~921) j7
* The values in the parentheses show the retentions.
(2) Each of the films shown in Table 7 was immersed
in a refrigerator oil (Suniso 3GS) in an autocla~e, and
after elevating the temperature to 185C, was maintained at
this temperature for 48 hours. The properties of the films
after this treatment, and the retentions of the properties
are shown in Table 9 below.
o2~
~o367~9
Table 9
~ . ~
Properties after treatment
.
Runs Tensile strength Elongation at
(Kg/cm ) break (%)
.. .. . ~ .
Example 11 2020 (71) 52 (76)
Example 12 1770 (65) 42 (65)
Control 6 1760 (63) ~ 27 (38)
* The values in the parentheses show the retentions
(3) Each of the films shown in Table 7 was
wrapped with a stainless steel net and suspended in a l-liter
autoclave. 100 cc of water was added to the autoclave so
that the water did not come into direct contact with the
film. After sealing the autoclave, the temperature was
raised to 150C., and the film was maintained at this tempera-
ture for 40 hours. The properties of the films after
treatment and the retentions of these properties are shown
in Table 10,
~/
103~>779
T~ble 10
.
Properties after treatment
._ _ .
Runs
Tsnsile strength Elongation at
(Kg/cm ) break t%)
. _ _ ._ .
Example 11 1720 (60) 35 (51)
Example 12 1210 (44) 16 (24)
Control 6 590 (21) 3 (4)
' - _ _ _
* The values in the parentheses show the
retentions.
.`
.
(4) Each of the films shown in Table 7 was
placed in a Gear oven held at 235C., and maintalned at
this temperature for 45 hours. The properties of the
films after the treatment, and the retentions of the
properties are shown in Table 11.
103~.77g
Table 11
Properties a~ter treatment
Runs _ j _ . ~ .
Tensile strength Elongation at break
(I~g/cm ) (%)
- - ~_ _, . ,
Example 11 1290 (45) 82 (120)
Example 12 1230 (45) 37 (57)
Control 6 1060 (38) 5 (7)
_
*The values in the parentheses show the
retentions.
,~_
