Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
873
BACKGROUND OF THE INVENTION
The present invention relates to a biaxially
oriented paraphenylene sulfide block copolymer film showing
a heat shrinkage of 0 - 2.0% at 100 - 220C and a process
for producing such film. More particularly, the present
invention relates to a biaxially oriented paraphenylene
sulfide block copolymer film showing a heat shrinkage of
0 - 2.0% at 100 - 220C, comprising a paraphenylene sulfide
block copolymer essentially composed of recurriny units (A):
-t ~ -S ~- and recurring units (B): ~ -S ~- , the
molar fraction of recurring units (A) being 0.50 - 0.98,
and having a melt viscosity (n*) of 1,000 - 15,000 poises
as measured at 310C and shear rate of 200 sec 1, a glass
transition temperature (Tg) of 20 - 80C, a crystalline
melting point (Tm) of 250 - 285C and a crystallization
index (Ci) of 15 - 45 (measured with the non-stretched
heat-treated polymer film), and a process for producing a
paraphenylene sulfide block copolymer oriented film showing
a heat shrinkage of 0 - 2.0% at 100 - 220C, which comprises
melt extruding and molding said paraphenylene sulfide block
copolymer into a film, stretching the thus molded ilm at
a temperature of 85 - 110C, and heat-setting the thus
stretched film at a temperature which is in the range of
250 - 275C and further defined by the following ~ormula:
200 ~ 15 log n* < THS ~ 182.5 ~ 22.5 log n*
- 2 -
~L~8~L~373
(wherein THS is heat-setting temperature, and ~* is melt
viscosity as measured at 310C and shear rate of 200 sec 1).
Paraphenylene sulfide polymer is known as a
thermoplastic resin having high heat-resistance and high
chemical-resistance and excellent electrical properties
since the paraphenylene sulfide polymer can be used at its
working temperature as high as nearly the crystalline
melting point (about 285C) by crystallizing it to a high
degree because of its high crystallinity (see, for instance,
Japanese Patent Publication No. 52-12240 (1977), ~apanese
Patent Publication No. 45-3368 (1970), Japanese Patent
Application Laying Open (KOKAI) No. 59-22926 (1984) and
U. S. Patent No. 3,869,434). Also, some films made of such
paraphenylene sulfide polymers and the processes for produc-
ing such films have been proposed.
For instance, there have been proposed a biaxially
oriented poly-p-phenylene sulfide film containing more than
90~ by mole of recurring units: -~ ~ - S ~- and having
a density of 1.330 - 1.400 g/cc at 25C, produced by melt
extruding and molding a poly-p-phenylene sulfide having a
melt viscosity in the range of 100 - 600,000 poises as
measured at 300C and shear rate of 200 sec 1 to orm a
non-crystalline (amorphous) transparent film, biaxially
stretching the thus obtained film simultaneously or succes-
sively at 80 - 120C, and heat-setting the thus stretched
lX~3~873
film under tension at a temperature in the range from 180C
to the melting point of the polymer (Japanese Patent Publi--
cation No. 59-5100 (1984)); a biaxially oriented poly-p-
phenylene sulfide film having a film-to-film kinematic
friction coefficient of greater than 0.75 at 20C and 70~
~I and a film surface roughness of less than 0.9 ~/ 5mm on
the average, obtained by producing a poly-p-phenylene sulfide
containing not less than 90~ by mole of recurring units:
- S ~- by polymerization, melt extruding and molding
this polymer to form a non-crystalline (amorphous) film,
biaxially stretching this film at a temperature of 80 - 100C
and heat-setting the thus biaxially stretched film at a
temperature of 150 - 280C, wherein the particles of an
inert inorganic material such as silica, alumina, carbon,
glass, calcium carbonate, calcium phosphate or the like are
added during or at the end of the polymerization, a
determined amount of insoluble salt used in the polymeriza-
tion is left, or the film is treated by a surface roughening
roll in the film forming process or subjected to surface
oxidation treatment or blast f.inishing with a solid matter
(Japanese Patent Application Laying Open (KOKAI) No. 55-
34968 (1980)); a process for producing a poly-p-phenylene
sulfide film comprising melt extruding and molding poly-p-
phenylene sulfide containing not less than 90~ by mole of
recurring units: -~ ~ -S ~- to form a substantlally
~;~8~373
amorphous film, stretching this film by 2.0 - 5.0 times in
one direction at 80 - 120C to make the birefrigence index
of the film 0.05 - 0.30, further stretching the thus obtained
film by 1.5 - 5 times in the direction orthogonal to the
initially stretched direction at a temperature of 80 - 150C,
and heat-settiny the thus treated film under tension at a
temperature in the range from 180C to the melting point of
the polymer (Japanese Patent Application Laying Open (KOKAI)
No. 55-111235 (1980)); a process for produciny a poly-p-
phenylene sulfide film, comprising melting a poly-p-phenylene
(amorphous) sulfide containing not less than 90% by mole
of recurring units: -~ ~ -S ~- and having a melt viscosity
of 100 - 600,000 poises as measured at 300C and shear rate
of 200 sec 1, extruding the melt onto a cooling medium
having a surface temperature of 120C or below to form a
film having a density of 1.320 - 1.330 g/cc, uniaxially
stretching the thus obtained film by 3 - 4.7 times at 85 -
100C, then further stretching the thus stretched film by
2.7 - 4.5 times in the orthogonal direction to the initially
oriented direction at 87 - 110C and heat-setting the thus
treated film at 200 - 275C (Japanese Patent Application
Laying Open (KOKAI) No. 56-62128 (1981)); a biaxlally
oriented poly-p-phenylene sulfide film having a gradient of
0.01 - 1.0 kg/mm2/% at 20% elongation in the stress-strain
curve when a 10 mm film piece cut out from said film in the
~ Z81~3~73
longitudinal and transverse directions is stretched at a
rate of 600 %/min at 25C, produced by melt extruding and
molding a poly-p-phenylene sulfide containing not less than
90~ by mole of recurring units: -~ ~ -S ~- and having
a melt viscosity of 300 - 100,000 poises as measured at
300C and shear rate of 200 sec 1 to form a substantially
amorphous film, biaxially stretching this film simultaneously
or successively at a temperature of 80 - 120C, and heat-
setting the thus stretched film under tension at a tempera-
ture in the range from 180C to the melting point of the
polymer for 1 - 10 minutes (Japanese Patent Application
Laying Open (KOXAI) No. 56-62127 (1981)); a process for
producing a poly-p-phenylene sulfide film comprising melt
extruding and molding a poly-p-phenylene sulfide containing
not less than 90~ by mole of recurring units: -~ ~ -S -
~to form a non-crystalline (amorphous) poly-p-phenylene
sulfide film, biaxially stretching this film at 80 - 100C,
heat-setting the thus stretched film at 150 - 280C, and
subjecting the thus treated film to a heat treatment at a
temperature in the range below the heat-setting temperature
but above 50C or sub~ecting the thus treated film to a
heat treatment at a temperature in the range below the
heat-setting temperature but above 50C while shrinking or
stretching within 20% in the longitudinal and transverse
directions (Japanese Patent Publication No. 59-5099 (1981));
8~ 73
and a base film for magnetic recording media having a
Young's modulus not less than 250 kg/mm at 20C at least
in one direction and a thermal expansion coefficient ln the
range of -2 x 10 4 - 2 x 10 4 mm/(mm C) in the temperature
of 20 - 150C, produced by melt extruding a poly-p-phenylene
sulfide containing not less than 90~ by mole of recurring
units~ S -~ , cold casting the thus obtained film,
biaxially stretching the thus treated film simultaneously
or successively and then subjecting the thus stretched film
to crystallization heat treatment under tension at 180 -
280C (Japanese Patent Application Laying Open (KOKAI) No.
55-38613 (1980)).
Paraphenylene sulfide polymer, however, has the
problem that its crystallization rate is too high in the
melting work and it tends to form coarse spherulites. For
instance, in case of forming a film by inflation method,
the polymer is crystallized and hardened before a sufficient
expansion occurs, and it is difficult to obtain a desired
oriented film. Also, in case of extruding and molding the
polymer into a sheet by a T-die, crystallization and
hardening take place before the sheet is taken up on a
take-up roll, and it is unable to obtain a flat and smooth
sheet having a uniform thickness.
For overcoming these problems in workin~ of
paraphenylene sulEide polymer, there has been proposed
873
an injection molding article, extrusion molding article or
wire-coating article of a paraphenylene sulfide block
copolymer essentially composed of recurring units (A).
-~ ~ -S ~- and recurring units (B)~ - S ~- , in
which the recurring units A exist as a bonded block of
average 20 to 5,000 units of the recurring unit (A) in the
molecular chain and the molar fraction of recurring units
(A) is in the range of 0.50 - 0.98, said copolymer having
a melt viscosity (n*) of 50 - 100,000 poises as measured at
310C and shear rate of 200 sec 1, a glass transition
temperature (Tg) of 20 - 80C, a crystalline melting point
(Tm) of 250 - 285C and a crystallization index (Ci) of 15
- 45 (measured with the non-oriented heat-treated polymer
film) (Japanese Patent Application Laying Open (KOKAI) No.
61-14228 (1986)).
The paraphenylene sulfide block copolymer which
is essentially composed of recurring units (A): -~ ~ -S~-
and recurring units (B). -~ ~ -S~- , wherein the recurring
units (A) exist as a bonded block o~ average 20 - 2,000
units of the recurring unit (A) in the molecular chain and
the molar fraction of recurring units (A) is in the range
of 0.50 - 0.98, and which has a melt viscosity (n*) of
1,000 - 15,000 poises as measured at 310C and shear rate
of 200 sec~l, a glass transition temperature of 20 - 80C,
a crystalline melting point of 250 - 285C and a crystal-
lization index of 15 - 45 (measured with the non-stretched
heat-treated polymer film), has the same degree of crystal-
linity and heat resistance as paraphenylene sulfide homo-
polymer, is free of the problems in melt works of the
homopolymer and also has a salient working characteristic
that it can be well molded and worked even in a supercooling
temperature range.
Recently, metallic thin-film tape is popularly
used as magnetic tape for enhancing recording density.
Fe, Ni, Co, their alloys and ferromagnetic compounds such
as ferrite are used for the magnetic layer of the metallic
thin-film tape. The thickness of the film is on the order
of several micronmeters or less. In such metallic thin-film
magnetic tape, it is important that the magnetic layer be
fastly bonded on a plastic base film which has a certain
limitation in heat resistance, without causing heat deterio-
ration of the base film. Hitherto, polyester film has been
used as such plastic base film.
However, the conventional polyester film is
unsatisfactory in heat resistance. Also, this base Eilm
is subject to heat deterioration by the heat from the
high--temperature evaporation (deposition) source ~nd the
latent heat of the magnetic atoms which come flying thereto
in the course of vacuum evaporation (deposition). The
examples of such heat deterioration are diversified from
~8~a73
local creasing, pinholes and fusion to the serious flaws on
the product. Under these circumstances, a new proposal of
a film having excellent heat resistance for use as base film
for metallic thin-film type magnetic tape has been desired.
As a result of studies on the subject matter,
the present inventors found that by after stretching a
paraphenylene sulfide block copolymer film, heat~setting
the thus stretched film in a specific temperature range,
it is possible to produce a biaxially oriented paraphenylene
sulfide block copolymer film showing a proper degree of
heat shrinkage, which film is free of the problem of heat
deterioration by the heat from the high-temperature evapora-
tion (deposition) source and the latent heat of the magnetic
atoms coming flying thereto in the course of vacuum evapora-
tion (deposition), and has easy melt workability, excellent
dimensional stability at high temperatures and good coherence
to the metallic rolls whereby the film cooling effect is
increased and the rise of film temperature suppresses to
the minimum in the course of vacuum evaporation (deposition).
The present invention was attained on the basis of such
finding.
SUMMARY OF THE INVENTION
In a first aspect of the present invention, there
is provided a biaxially oriented paraphenylene sulfide block
-- 10 --
~Z~3~87~
copolymer film showing a heat shrinkage of 0 - 2.0% at 100
- 220C, comprising a paraphenylene sulfide block copolymer
essentially composed of recurring units (A): -~ ~ -S ~-
and recurring units (B)~ S ~- , the molar fraction
of recurring units (A) baing 0.50 - 0.98, and having a melt
viscosity (n*) of 1,000 - 15,000 poises as measured at
310C and shear rate of 200 sec 1, a glass transition tem-
perature (Tg) of 20 - 80C, a crystalline melting point (~m)
of 250 - 285C and a crystallization index (Ci) of 15 - ~5
(measured with the non-stretched heat-treated polymer film).
In a second aspect of the present invention,
there is provided a process for producing a biaxially
oriented paraphenylene sulfide block copolymer film showing
a heat shrinkage of 0 - 2.0% at 100 - 220C, comprising
melt extruding and molding a paraphenylene sulfide block
copolymer essentially composed of recurring units (A):
-~ ~ -5 -~ and recurring units (B): -~ ~ -S~- , the
molar fraction of recurring units (A) being 0.50 - 0.98,
and having a melt viscosity (n*) of 1,000 - 15,000 poises
as measured at 310C and shear rate of 200 sec 1, a glass
transition temperature (Tg) of 20 - 80C, a crystalline
mel~iny point (Tm) of 250 - 285C and a crystallization
index (Ci) of 15 - ~5 (measured with the non-stretched
heat-treated polymer film), into a film, and after stretch-
ing the molded film, heat-setting the thus stretched film
-- 11 --
1~81873
at a temperature which is in the range of 250 - 275C and
further defined by the formula:
200 ~ 15 log n* < THS < 182.5 + 22.5 log n*
(wherein THS is heat-setting temperature, and ~* is melt
viscosity as measured at 310C and shear rate o~ 200 sec 1).
BRIEF DESCRIPTION OF THE DRAWING
FIG. 1 is a drawing showing the relation between
heat-setting temperature (C) and shrinkage (%).
DETAILED DESCRIPTION OF THE INVENTION
.. . .
The polymer of the biaxially oriented paraphenylene
sulfide block copolymer film according to the present
invention is essentially composed of recurring units (A):
-~ ~ -S ~- and recurring units (B): -~ ~ -S ~- , in which
the recurring units (A) exist as a bonded blocks of average
20 - 2,000 units of the recurring unit (A) in the molecular
chain and the molar fraction of recurring units (A) is in
the range o~ 0.50 - 0.98, and has a melt viscosity (~*) of
1,000 - 15,000 poises as rneasured at 310C and shear rate
of 200 sec~l, a glass transition temperature of 20 - 80C,
a crystalline melting point of 250 - 285C and a crystal-
lization index of 15 - ~5 (measured with the non-s-tretched
heat-treated polymer film).
- 12 -
~8~73
The crystalline p-phenylene sulfide block copolymer
of the present lnvention is a high-molecular material having
a chemical structure in which the recurring units (A):
-~ ~ -S ~- are bonded block-wise in the molecular chain.
For providing this copolymer with heat resistance
based on crystallinity characteristic of p-phenylene sulEide
homopolymer and with the working easeability in inflation
film ~orming, melt extruding and molding, wire coating,melt
spinning and drawing, etc., it is indispensable that the
p-phenylene sulfide recurring units (A) of this copolymer
be distributed in the molecular chain as bonded blocks of
20 - 2,000 units, preferably 40 - 1,500 units, more prefer-
ably 100 - 1,000 units on the average.
It is also necessary that the molar fraction of
the recurring unlts (A) in the copolymer molecular chain
is in the range of 0.50 - 0.98, preferably 0.60 - 0.90.
When the p-phenylene sulfide recurring units are in the
above-mentioned range, this copolymer has crystallinity and
heat resistance equal to p-phenylene sulfide homopolymer
and is also excellent in workability for inflation film
forming, melt extrusion, wire coating, melt spinning and
drawiny, etc.
The recurring units (B) which cons-titute the
block copolymer with the p-phenylene sulfide recurring
units (A), essentially comprise meta-phenylene sulfide
- 13 -
73
recurring units~ S ~- in which aromatic compound
recurring units: -~ Ar -S -~ may be contained. In this
formula, Ar represents an aromatic compound residueO
Typical examples of -~ Ar -S -~ may exemplify -~ ~ -S -~,
O O
S ~, ~- C -~- S ~ ~ )~ S
-~ ~ -O - ~ -S ~ and -~ ~ - ~ -S ~- .
The term "essentially" is used in the present
invention to signify that m-phenylene sulfide units occupy
not less than 80~ by mole, preferably 90 to 100% by mole
of the whole recurring units (B).
The polymerization degree of the paraphenylene
sulfide block copolymer of the present invention, as
eY~pressed in terms of melt viscosity (n*), is in the range
of 1,000 - 15,000 poises. The melt viscosity (n*) is
represented as measured under the conditions of 310~C and
shear rate of 200 sec 1 by using a Koka-type flowtester.
If the melt viscosity (n*) is less than 1,000 poises, no
tenacious molded product can be obtained.
The number of the recurring units (A): -~ ~ -S-~ ,
that ls, the polymerization degree of poly-paraphenylene
sulfide blocks in the block copolymer of the present
invention can be determined by fluorescent X-ray method,
and the polymerization degree of poly-metaphenylene sulfide
-- 1~ --
~8~373
blocks (B) can be measured by yel permeation chromatography
(GPC). The molar fraction of poly-paraphenylene sulfide
blocks can be easily determined by infrared analysis.
Further, the paraphenylene sulfide block copolymer
of the present invention has a glass transition temperature
(Tg) of 20 - 80C and a crystalline melting point (Tm) of
250 - 285C, and a crystallization index (Ci) of 15 - ~5
(measured with the non-stretched heat treated polymer film).
The paraphenylene sulfide block copolymer of the
present invention is also characterized by the fact that
the crystallization temperature (Tc2) on the high tempera-
ture side (viz. the temperature at which the crystallization
begins when the polymer in the molten state is cooled
gradually) is widely different from the crystalline melting
point (Tm) and also the crystallization rate is not so high,
contrastive to p-phenylene sulfide homopolymer in which
Tc2 is close to Tm and the crystallization rate is very
high. Therefore, the paraphenylene sulfide block copolymer
of the present invention has a very advantageous working
characteristic that it can be well molded and worked even
in the temperature region between Tm and Tc2, that is, in
the supercooliny temperature range, and is thus suited for
various types of working.
Tm, Ty, Tcl and Tc2 are the values expressed by
the melt peak, the temperature causing the start of heat
- 15 --
~LX~ 3
absorption and the crystallization peak, respectively, as
they were measured with 10 mg of specimen, which has been
quenched from the molten state into a substantially non-
crystalline (amorphous) state, under nitrogen gas atmosphere
at a heating and cooliny rate of 10C/min by using a
differential scanning type calorimeter mfd. by Metler Corp.
(DSC Metler TA-3000).
The crystallization index (Ci) of the paraphenylene
sulfide block copolymer of the present invention, which has
been heat-treated but not stretched, is in the range of 15
- 45. This crystallization index (Ci) is a value calculated
from the formula: Ci = [Ac/(Ac -~ Aa)] x 100, by separating
the crystalline scattering strength (Ac) and non~crystalline
scattering strength (Aa) at 20 =17 -23 from the X-ray
diffraction pattern [J. Appl. Poly. Sci., 20, 2545 (1976)].
Ci shown in the present invention is the value obtained
from the measurement on the heat-treated film made by melt
pressing the block copolymer by a high-tempexature press at
a temperature about 30C higher than the melting point,
rapidly cooling the thus melt pressed film with water to
form a 0.1 - 0.2 mm thick film, and heat treating the thus
obtained film for 20 min at a temperature 20C lower -than the
melting point for effecting crystallization. In the case of the
oriented and then heat-treated film, Ci is higher, usually
in the range of ~0 - 90.
- 16 -
~.~8~8~3
Typical examples of the preparation process of
paraphenylene sulfide block copolymer according to the
present invention are shown below.
(I) A non-protonic polar organic solvent containing
paradihalobenzene and an alkaline metal sulfide is heated
to produce a reaction solution (C) containing a para-
phenylene sulfide polymer in which the number of recurring
units (A): ~ -S -~ is 20 - 2,000 on the average
(first step), and this reaction solution (C) is added with
a dihalo aromatic compound substantially composed of
metadihalobenzene and the thus obtained mixture is heated
for effecting block copolymerization so as to obtain a
paraphenylene sulfide block copolymer comprising the
recurring units (A): ~ S~- and recurring units (B):
-~ ~ -S~- , in which the molar fraction of recurring units
(A) is in the range of 0.50 - 0.98, and having a melt
viscosity (n*) of 1,000 - 15,000 as measured under the
conditions of 310C and shear rate of 200 sec 1, a glass
transition temperature (Tg) of 20 - 80C, a crystalline
melting point (Tm) of 250 - 285C, and a crystallization
index (Ci) of 15 - ~5 (measured with the non-stretched
heat-treated polymer film).
(II) A non-protonic polar organic solvent containing
a dihalo aromatic compound composed of metadihalobenzene
8~;3
and an alkaline metal sulfide is heated to
produce a reaction solution (E) containi.ng a
metaphenylene sulfide polymer comprising recurrin~
units (B)~ S~- , having an average polymerization
degree of not less than 2 and satisfying the relation of
(20 x 1 y ~ ) ~ (2,000 x l y Y ) (wherein Y is the molar
fraction of recurriny units (A) of the produced block
copolymer, of 0.50 - 0.98) (first s-tep), and this reaction
solution (E) is added with paradihalobenzene and the thus
obtained mixture is heated for effecting block polymeriza-
tion so as to obtain a paraphenylene sulfide block copolymer
comprising the recurring units (B): ~ ~ -S~- and
recurring units (A): -~ ~ -S~- , in which the molar
fraction of recurring units (A) is in the range of 0.50 -
0.98, and having a melt viscosity (n*) of 1.,000 - 15,000 as
measured at 310C and shear rate of 200 sec 1, a glass
transition temperature (Tg) of 20 - 80C, a crystalline
melting point (Tm) of 250 - 285C, a crystallization index
(Ci) of 15 - 45 (measured with the non-stretched heat-
treated polymer film).
The alkaline metal sulfide used as sulfide bond
supply source is preferably selected from the sul~ides of
such metals as Na, Li, K, Rb and the like, among which the
sulfides of Na and Li are especially preferred in view of
reactivity. In case such sulfide contains crystal water,
- 18 -
~'~8~ 73
it is necessary to reduce its water content by suitable
means such as evaporation or drying before it is used for
the polymerization reaction.
Carboxylic acid amides, organophosphoric acid
amides, urea derivatives and the like can be preferably
used as non-protonic polar organic soIvent in the reaction,
but in view of chemical and thermal stability, N-methyl-
pyrrolidone, hexatrimethylphosphoric acid triamide,
tetramethylurea and the like are especially preferred.
In the dihalo aromatic compound, paradichloro-
benzene, paradibromobenzene and the like can be used as
paradihalobenzene for forming the p-phenylene sulfide
blocks, while dihalo subs-tituted aromatic compounds can be
used in a small quantity with the above-mentioned metadihalo-
benzene for forming other blocks. Typical examples of such
dihalo substituted aromatic compounds are those shown by
X Y O
the formulae: X ~ - Y, ~ , X - ~ - C - ~ -Y,
X- ~ - ~ -Y, X - ~ -O - ~ -Y, and X - ~ -~ - ~ -Y
(wherein X and Y are each a halogen atom).
It is also possible to use polyfunctional com-
pounds having three or more halogen groups such as 1,2,3-
or 1,2,~-trihalobenzene.
-- 19 --
873
The polymerization conditions should be selected
so that a polymer having a melt viscosity (n*) of 1,000 -
15,000 poises, preferably 1,050 - 15,000 poises, is formed.
The preparation processes will be described more
particularly below.
Preparation process (I)
In case of using an alkaline metal sulfide contain-
ing crystal water as starting material, such as Na2S-9H2O,
Na2S-5H2O and Na2S-3H2O (including those produced from an
in situ reaction of NaHS-2H2O + NaOH ~ Na2S-3H2O), it ls
preferable (i) to reduce the water content to a proper
level by drying and then feed the thus dried compound into
an organic solvent, (ii) to feed the alkaline metal sulfide
alone into an organic solvent and heat the thus obtained
mixture to about 200C thereby distilling off water, or
(iii) to carry out chemical dehydration by adding, for
example, CaO thereby properly adjusting the water content
(usually 0.5 - 2.5 moles to one mole of sulfide). There-
after, p-dihalobenzene is added thereto in an amount
corresponding to 0.95 - 1.05 moles to one mole of sulfide,
and the mixture is heated to a proper temperature, usually
160 - 300C, preferably 190 - 260C, to carry out poly-
merization reaction until the average polymerization de~ree
oE the produced p-phenylene sulfide prepolymer becomes 20
2,000, thereby forminy a prepolymer-containing reacted
- 20 -
~LX8~3t73
mixture solutlon (C). The time required for this process
is usually about 0.5 - 30 hours.
On the other hand, an unreacted mixture solution
(D) is prepared by adding metadihalobenzene (which may
contain a small quantity of dihalo substituted aromatic
compound) to the starting alkali metal sulfide in an amount
corresponding to 0.95 - 1.05 mole to one mole of sulfide,
after adjusting its water content by drying, distillation
in the organic solvent or chemical dehydration in the same
way as described above.
The unreacted mixture solution (D) and the
prepolymer~containing reaction mixture solution (C) are
mixed in a proper ratio (viz. a ratio selected such that
the molar fraction of paraphenylene sulfide recurring units
in the produced block copolymer would become 0.50 - 0.98),
and after re-adjusting the water content if necessary, the
mixture is again heated to a proper temperature, usually
160 - 300C, preferably 200 - 280C, to carry out poly-
merization re~ction. There can resultantly be obtained a
crystalline paraphenylene sulfide block copolymer of the
present invention.
The polymer can be xecovered in a granular or
powdery form by subjecting the thus obtained polymer to
neutralization, filtration, washing and drying as desired
in the conventional method.
~;~8~873
Preparation process (II)
Assuming that the average length (polymerization
degree) of the blocks of paraphenylene sulfide recurring
units (A) is n, the molar fraction is Y and the average
length (polymerization degree) of the blocks of recurring
units (B) mainly composed of metaphenylene sulfide is m,
there generally exists the following relation:
n : m = Y ~ Y)
.-.m = n x (1 - y)
Therefore, in the case of a block polymer in
which n =20~2,000, there exists the relation:
m = (20 x 1 y Y ) ~ (2,000 x 1 y Y ) (m must not be less
than 2). This relation is applied in the preparation
process (II).
In this process, as the case of the preparation
process tI), a polar organic solvent and a starting alkaline
metal sulfide are fed after properly adjusting the water
content thereof, and then metadihalobenzene (whi.ch may
contain a small quantity of dihalo substituted aromatic
compound) is added thereto in an amount corresponding to
usually 0.95 - 1.05 mole to one mole of sulfide. Then the
mixture is heated to a proper temperature, usuall.y 160 -
300C, preferably 190 - 260C, to carry out polymerization
reaction until the average polymerization degree of the
- 22 -
~L~8~373
produced arylene sulfide prepolymer would become ~20 x 1 y Y
(2,000 x l y Y~), thereby preparing a prepolymer-
containing reaction mixture solution (E).
On the other hand, an unreacted mixture solution
(F) is prepared by feediny a polar organic solvent and a
starting alkaline metal sulfide after adjusting the water
content thereof in the same way as the preparation process
(I) and then adding p-dihalobenzene thereto in an amount
corresponding to usually 0.95 - 1.05 mole to one mole of
sulfide. (As mentioned before, the essential component of
the mixture solution (F) may be p-dihalobenzene alone, with
no sulfide and solvent contained).
The unreacted mixture solution (F) and the pre-
polymer-containing reaction mixture solution (E) are mixed
in a predetermined ratio, and after re-adjusting the water
content thereof, if necessary, the mixture is again heated
to a proper temperature, usually 160 - 300C, preferably
200 - 280C, to accomplish polymerization reaction, thereby
obtaining a crystalline p-phenylene sulfide block copolymer
of the present invention. Recovery and purification of
the polymer can be performed in the same way as preparation
process (I).
The thus produced polyphenylene sulfide block
copolymer is melted by heating to the crystalline melting
point (Tm) or higher and then molded into a sheet or film
- 23 -
~81~73
by a T-die or the like joined to a press or an extruder,
and the thus molded material is cooled rapidly to produce
a non-crystalline (amorphous) film or sheet. This rapid
cooling is preferably conducted at a cooling rate of at
least 10 C/sec to provide a transparent sheet with a
crystallization degree of not more than 20%. If the cooling
rate is lower than 10 C/sec, the growth of crystal is
advanced and causes opacification and embrittlement of the
produced film.
The thus obtained non-crystalline (amorphous)
transparent sheet is stretched at a temperature of 85 - 110C
by rolling or tentering, and then heat-set at a temperature
which is in the range of 250 - 275C and further defined
by the formula:
200 + 15 log n* _ THS < 182.5 + 22.5 lo~ n*
(wherein THS is heat-setting temperature, and n* is melt
viscosity as measured at 310C and shear rate of 200 sec 1).
In this way, it is possible to obtain a biaxially oriented
paraphenylene sulfide block copolymer film showing a heat
shrinkage of 0 - 2.0%, preferably 0.1 - 1.8%, at 100 - 220C,
comprisin~ a paraphenylene sulfide block copolymer essential-
ly composed of recurring units (A)~ S~- and
recurring units (B): -~ ~ -S-~ , the molar fraction of
recurring units (A) being 0.50 - 0.98, preferably 0.70 -0.90,
- 2~ -
a73
and having a melt viscosity (n*) of l,ooo - 15,000 poises
as measured at 310C and shear rate of 200 sec 1, a glass
transition temperature (Tg) of 20 - 80C, preferably 45 -
80C, a crystalline melting point (Tm) of 250 - 285C,
preferably 265 - 278C, and a crystallization index (Ci) of
15 - 45, preferably 20 - 45 (measured with the non-stretched
heat-treated polymer film).
Since the heat-set film which expands in the tempexature
of 100 - 220C (heat shrinkage < 0) may not adhere to the cooling
metal roll in the working heat treatment such as vacuum evapora-
tion (deposition), such a film is not preferable. Also,
the oriented film showing a heat shrinkage of more than
2.0% is undeslrable in respect of work precision.
By stretching the film usually not less than 6
times, preferably not less than 8 times as large as the
original surface area of the film, it is possible to obtain
a stretched film having a high intra-facial tension of
molecular chain. In the case of successively biaxially
stretching, the first-stage stretching ratio is preferably
not more than 5 times. If the first~stage stretching ratio
is more than 5 times, there may be caused not only an
increase of tension of molecular chain but also a high-
degree crystallization or a whitening phenomenon which
gives an adverse effect to the film in the second-s-tage
stretching.
- 25 -
~,2s~a73
The drawing rate is preferably in the range of
500 - 20,000 %/min. If it is lower than 500 %/min, non-
uniformity of orientation may be caused, while if the
drawing rate is more than 20,000 %/min, there may occur a
whiteniny phenomenon or cut off the film.
The present invention is characterized in that
the stretched film is heat-set at a temperature which is
in the range of 250 - 275C and further defined by the
formula: 200-~15 log n* < THS < 182.5 -~ 22.5 log n*.
For obtaining a biaxially oriented polyphenylene
sulfide block copolymer film showing a heat shrinkage of
0 - 2.0~ at 100 - 220C and having excellent dimensional
stability in the working heat treatment such as vacuum
evaporation and good workability, it is necessary to adjust
the heat-setting temperature of the stretched fllm in a
spe~ific range in confo'rmity to the melt viscosity.
For instance, the heat-setting temperature for
a film comprising a polymer having a melt viscosity of
1,000 poises should be 250C, and that of a film comprising
a polymer having a melt viscosity of 2,500 poises should
be 250.9 - 25~.9C. Also, in the case of a film comprising
a polymer having a melt viscosity o~ 7,600 poises, the
heat-setting temperature should be deEined to a relatively
narrow range of 258.2 - 269.8C.
If the heat-set-ting temperature is less than
- 26 -
8~7~
250C~ it is substantially difficult to obtain a film having
excellent dimensional stability, and the obtained film is
unsuited for use as a base film of a magnetic recording
medium for high-density recording. Also, if the heat-setting
temperature is more than 275C/ it is difficult to obtain
a film which shows the desired shrinking behavior in the
temperature of 100 - 220C. Even if the heat-setting
temperature is in the range o~ 250 ~ 275C/ no satisfactory
shrinking behavior can be obtained unless the melt viscosity
(n*) of the film used is in a proper range. If the melt
viscosity (n*) is too low, no satisfactory shrinking
behavior is shown even if heat-setting is conducted at
250C, and there is obtained a film showing an expanding
behavior. Further, if the melt viscosity (n*) is too high,
there is obtained a film which shows too large shrinkage
for-practical use. Such film is poor in dimensional
stability or may break in the course of heat-setting
treatment.
For obtaining a film showing a heat shrinkage of
0 ~ 2.0~o at 100 - 220C/ it is necessary to heat-set the
film at a temperature specified by the above-mentioned
formula which accords with the melting behavior of the film
used. When heat-setting is conducted in this temperature
range, there can be obtained a film showing a proper
shrinking behavior, and when such film is subjected to a
873
metallization treatment (metal vacuum evaporation) at a
high temperature, the film can well adhere to the cooling
metal roll and therefore the cooling effect by the roll is
enhanced to facilitate the metallization treatment.
The heat-setting time, though variable according
to the desired properties of the produced film, is usually
in the range from 3 seconds to several ten minutes, prefer-
ably 3 - 600 seconds. By the heat-setting treatment of
from 3 seconds to several ten minutes, there mainly takes
place crystallization and a thermally stabilized film can
be obtained. If the heat-setting time is longer than the
above-mentioned range, there may take place undesirable
phenomena such as excessive coloration or embrittlement of
the film.
The present invention provides a biaxially
oriented paraphenylene sulfide block copolymer film showing
a heat shrinkage of 0 - 2~ and a process for producing such
film. By using the biaxially oriented paraphenylene sulfide
block copolymer film as base film and depositing thereon
Fe, Ni, Co, their alloys or a ferromagnetic compound such
as ferrite, it is possible to produce a base film o a
magnetic recording medium for high-density recording.
The present invention will hereinafter be described
according to the examples thereof. These examples, however,
are merely illustrative and not limi-tive of the scope of
the invention.
- 28 -
373
Synthesis Example 1
8.0 kg of N-methylpyrrolidone (NMP) and 21.0 moles
of Na2S 5H2O were supplied into a 20-litre polymerization
pressure vessel and heated to about 200C to distil off
water (loss of S =1.5 mol%; water in the vessel =28 moles).
Then 20.1 moles of m-dichlorobenzene (m-DCB) and 3.1 kg of
NMP (calcd. Na2S concentration in the mixed solution -
1.342 mol/ky) were supplied thereto, and after the vessel
atmosphere replacement with N2, the mixture was polymerized
at 220C for one hour and then further reacted at 230C for
9 hours to prepare a reaction mixture solution (E-l). This
solution was taken out from the vessel and stored.
A small amount of (E-1) solution was sampled out
and the polymerization degree of the produced m-phenylene
sulfide prepolymer was measured (by GPC method). The
polymerization degree was 30.
8.0 kg of NMP and 20.0 moles of Na2S-5H2O were
fed into a 20-litre polymerization pressure vessel and
heated to about 200C to distil off water ~loss of S =1.5
mol%; water in the vessel =26 moles). Then 20.29 moles of
p-dichlorobenzene (p-DCB), 3.55 moles of water and 2.75 kg
of NMP were supplied thereto(mole ration of p-DCB to Na2S
in the mixture is 1.03); and the mixture was cooled under
stirring. The Na2S concentration in the mixed solution
was 1.322 mol/kg. The solution was taken out from the
- 29 -
873
vessel and mixed well to prepare an unreacted mixture solution
(F-l).
The reaction mixture solution (E-l) and unreacted
mixture solution (F-l) were supplied in a ratio of 2.25 kg
(E-l) to 12.58 kg (F-l) into a 20-litre polymerization
pressure vessel, and the mixture was reacted at 215C for
10 hours, then 1.24 ky of water was added thereto and the
thus obtained mixture was further reacted at 260C for 5
hours.
The thus obtained reaction mixture was filtered,
washed with hot water and dried under reduced pressure to
obtain the block copolymer.
The molar fraction (X) of the recurring units:
-~ ~ -S~- in the blocks, as measured by infrared analysis,
was 0.15. The melt viscosity (~*) as measured at 310C
and shear rate of 200 sec 1 by using a Koka type flowtester
was 1,800 poises.
Synthesis Examples 2 - 4
Unreacted mixture solutions (F-1) were prepared
in the same way as in Synthesis Example 1 except that the
p-DCB to Na2S molar ratio was changed to 1.02, 1.015 and
1.01, respectively, and each of these unreacted mixture
solutions (F-l) was supplied along with the reaction
mixture solution (E-l) into a 20-litre polymerization
- 30 -
~.28~37~
pressure vessel so that the mixture would contain 15 mol~
of recurring units (B)~ S~- , and they were reacted
in the same way as in Synthesis Example l to obtain the
corresponding block copolymers.
Synthesis Example 5
8.0 kg of N-methylpyrrolidone (NMP) and 20.0 moles
of Na2S-5~2O were supplied into a 20-litre polymerization
pressure vessel and heated to about 200C to distill off
water (loss of S =1.5 mol%; water in the vessel =26.4 moles).
Then 20.1 moles of p-dichlorobenzene (p-DCB), 3.15 moles
of water and 2.5 kg of NMP were supplied (Na2S concentration
in the mixture =1.325 mol/kg), and after atmosphere
replacement with N2, the mixture was polymerized at 210C
for 10 hours to prepare a reaction mixture solution (C-l). .,
This (C-l) solution was taken off from the vessel and
stored. A small amount of (C-l) solution was sampled out
and the polymerization degree of the produced p-phenylene
sulfide prepolymer was measured (by fluorescent X-ray
method). It was llO.
8.0 kg of NMP and 21.0 moles of Na2S-5H2O were
supplied into a 20-litre polymerization pressure vessel
and heated to about 200C to distill off water (loss of
S =1.5 mol%; water in the vessel =28.5 moles). Then 20.~85
moles of m-DC~ and 3.0 kg of NMP were supplied (Na2S
- 31 -
373
concentration in the mixture = 1.334 mol/kg), and the mixture
was cooled under stirring to prepare an unreacted mixture
solution (D-l). The solutlon was taken out of the vessel
and stored.
The reaction mixture solution (C-l) and the
unreacted mixture solution (D-l) were supplied in a ratio
of 13.91 ky (C-l) to 2.25 kg (D-l) into a 20-litre poly-
merization pressure vessel and reacted at 225C for 10 hours,
then added with 1.35 kg of water and further reacted at
260C for 5 hours. The reaction mixture was filtered,
washed with hot water and dried under reduced pressure to
obtain a block copolymer.
The obtained block copolymers were melted at
a temperature by about 30C higher than the melting point
and pressed by a high-temperature press and then cooled
rapidly with water to make 0.1 - 0.2 mm thick films. By
using the thus obtained films as samples, the copolymer
compositions were determined by infrared analysis (FT-IR
method). Tg, Tm, Tcl and Tc2 were also determined by using
these samples.
Each film was heat treated at a temperature 20C
lower than the meltiny point for 20 minutes for e~fectiny
crystallization and the crystallization index Ci of the
heat treated sheet was determined by X-ray diffractometry.
The results of determinations are shown in
Table 1.
~~`` 1~8~L~73
rl Ln ~ 0
u ~
oo ~ o ~~r
~ O , O o o o o
O E-~ ~ 1
.IJ
O ~1 co o a~ ooco
~1 E-~
t` I` I` 1-
E~
ro
t1~ ~
O o o o o
O o o o o
* C~
5~
r~ ,~ ~
~ ~ ~ O L~ r
E-l àP)~ ~ 1 r-l r-l r-l
O ~ ~
~ Q
,~
~0 ~ U~
CJ ~-r~ o o o o
~ ~ ~ . . . . I
rl ~ O r-l r-l rl r
0~'~
tn ~
t~l ~ ~ ~1
~ ~ ~ O
Zi S I h u~
~r~
n
~1
-- 33 --
373
Examples 1 - 4 & Comparative Example 1
Polyphenylene sulfide block copolymers containing
14 and 15 mole% of recurring units~ S-~ and havin~
different melt viscosities, obtained in Synthesis Examples
1 - 5, were extruded onto a 75 - 85C casting roll throu~h
a 35 mm~ extruder provided with a hard chrominum plated
screw at a resin temperature of 305C to form 245 mm thick
T-die sheets. Each of these sheets was biaxially stretched
3.5 times in ~e longitudinal and transverse directions
simultaneously at a stretching temperature of 95C, drawing
rate of 2,300 %/min and preheating time of 1 minute by
using a film stretcher mfd. by T. M. Long & Inc. The thus
obtained stretched films were respectively fixed to a metal
frame and heated at 260C for 10 minutes in the case of
the films of block copolymers of Synthesis Examples 1 - 4
and at 250C for 10 minutes in the case of the film of block
copolymer of Synthesis Example 5 to obtain transparent
films. The film thickness was about 20 ~m.
~ film piece of 5 mm in width and 20 mm in length
was cut out from each of the thus obtained biaxially
stretched film [(1) n* = 3,200 poises (Example 1), (2) n* =
4,600 poises (Example 2), (3) n* = 7,600 poises (Example 3),
and (4) n* = 1,800 poises (Comparative Example 1)], and each
film piece was heated at a heating rate of 10C/min under
a load of about 30 g/mm2 by using TMA (thermal machine
- 34 -
8~873
analyzer, mfd. by Shimazu Co., Ltd.) to determine the
thermal expansion/contraction behavior.
The results of determinations are shown in FIG. lo
The film of Exarnple 4 (n* = 1, 300 poises) obtained from
the block copolymer of Synthesis Example 5 showed a heat
shrinkage of 0.1% at 100C and 0.5% at 220C, and the heat
shrinkage in this temperature range was 0.1 - 0.5~. Each
film expands until it is heated to the temperature at which
the molecular motion of the non-crystalline portion becomes
active (that is, till reaching the glass transition tem-
perature). Above the glass transition temperature, the
expansion/contraction behavior differs according to the
working conditions. When the film is further heated,
crystal begins to melt and a sharp shrinkage occurs.
As seen from FIG. 1, in the case of the film of
Comparative Example l which has been heat-set at a tem-
perature outside the heat-setting temperature range
specified in the present invention (shown by 4 in FIG. l;
the film was heat-set at a higher temperature than the
temperature range specified in the present invention),
thermal expansion occurred and the adhesion to the metal
roll became poor at higher than 150C. Thus, this film was
unsuited for metallization (metal vacuum deposition) at
high temperat~lre.
In the case of the films of Examples 1 - 3 (the
- 35 -
873
film of Example 1 being shown by 1, the film of Example 2
being shown by 2 and the film of Example 3 being shown by
3 in FIG. 1) and the film of Example 4, which were all heat-
set in the temperature range specified in the present
invention, the heat shrinkage was 0 - 2% in the temperature
range of 100 - 220C and the adhesion to the metal roll was
also excellent. Thus, these films were suited for metal-
lization (metal vacuum deposition) at high temperature.
- 36 -
