Process for the preparation of polymer solution

A process for the preparation of a polymer solution comprises the steps of: mixing a polymer with a solvent to swell the polymer in the solvent; cooling the swelled mixture; and then warming the cooled mixture to dissolve the polymer in the solvent. The present invention uses a polymer other than cellulose esters of lower fatty acids to form the polymer solution.

FIELD OF THE INVENTION 
The present invention relates to a process for the preparation of a polymer 
solution. 
BACKGROUND OF THE INVENTION 
Polymers have been used in various technical fields. A polymer material 
such as a plastic film is formed by using a melt or solution of a polymer. 
A process of forming a polymer material comprises dissolving a polymer in 
a solvent to form a solution, forming a polymer material by using the 
solution, and drying the formed material by evaporating the solvent. 
The solvent of a polymer is a liquid that can dissolve a polymer at a 
required concentration. The solvent also requires safety and an 
appropriate boiling point for evaporating the solvent from a formed 
polymer material. Recently, the solvent particularly requires safety of 
the human body and the environment. Therefore, it is now rather difficult 
to find out an appropriate solvent in liquids that can dissolve a polymer. 
For example, methylene chloride has been used as a solvent of cellulose 
triacetate. However, the use of hydrocarbon halides such as methylene 
chloride has recently been restricted severely to protect the global 
environmental conditions. Further, methylene chloride may cause problems 
in the working environment. 
On the other hand, acetone is a widely used organic solvent. Acetone has an 
appropriate boiling point (56.degree. C.). Further, acetone has few 
problems on the human body and the global environmental conditions, 
compared with the other organic solvents. However, cellulose triacetate 
has a poor solubility in acetone. Cellulose triacetate can be swelled in 
acetone, but is scarcely dissolved in acetone. 
J. M. G. Cowie et al. report in Makromol., Chem., 143 (1971) 105-114, that 
cellulose acetate having a substitution degree in the range of 2.70 
(acetic acid content: 60.1%) to 2.80 (acetic acid content: 61.3%) is 
dissolved in acetone by a specific process. The process comprises the 
steps of cooling the cellulose acetate in acetone to a temperature of -80 
to -70.degree. C., and warming it to obtain 0.5 to 5 wt. % solution of 
the-cellulose acetate in acetone. The method of cooling a mixture of a 
polymer and a solvent to obtain a solution is hereinafter referred to as a 
cooling dissolution method. 
The solution of cellulose acetate in acetone is also reported by K. Kamide 
et al., Textile Machinery Society, Vol. 34, 57-61 (1981). The report 
(written in Japanese) is entitled "Dry spinning process using acetone 
solution of triacetyl cellulose." In the report, the cooling dissolution 
method is applied to the art of fiber spinning. The experiments shown in 
the report examine the mechanical strength, the dyeing property and the 
cross sectional profile of the fiber obtained by the cooling dissolution 
method. In the report, 10 to 25 wt. % solution of cellulose acetate is 
used to form a fiber. 
SUMMARY OF THE INVENTION 
An object of the present invention is to dissolve a polymer in a solvent 
according to an improved cooling dissolution method, even if the polymer 
is swelled in, but is not dissolved in the solvent by a conventional 
dissolution method. 
The present invention provides a process for the preparation of a polymer 
solution which comprises the steps of: mixing a polymer other than 
cellulose esters of lower fatty acids with a solvent to swell the polymer 
in the solvent; cooling the swelled mixture; and then warming the cooled 
mixture to dissolve the polymer in the solvent. 
As is described in the item of the Background of the Invention, the cooling 
dissolution method has been proposed to dissolve cellulose acetate in 
acetone. 
A lower fatty acid ester of cellulose such as cellulose acetate has a 
specific chemical structure, which is completely different from a 
synthetic polymer or other natural or semi-synthetic polymers such as 
gelatin. The lower fatty acid ester of cellulose is a specific 
semi-synthetic polymer, in which ester bonds combine lower fatty acids 
(having 1 to 6 carbon atoms) to free hydroxyl of glucose units polymerized 
with .beta.1-4 glycoside bond. The cooling dissolution method is effective 
in dissolving cellulose acetate in acetone. The specific effect of the 
cooling dissolution method has been considered to depend on the specific 
chemical structure of cellulose acetate. 
The applicants have studied the cooling dissolution method, and have 
surprisingly found that the cooling dissolution method is effective in 
dissolving a polymer other than cellulose esters of lower fatty acids in a 
solvent. 
The cooling dissolution method can dissolve the polymer other than 
cellulose esters of lower fatty acids in the solvent, even if a 
conventional dissolution method does not dissolve the polymer in the 
solvent. Further, the cooling dissolution method can prepare an excellent 
polymer solution of a high concentration in which insoluble materials or 
gels are not observed, even if a conventional dissolution method does not 
prepare the polymer solution of the high concentration. Furthermore, the 
cooling dissolution method can form a stable polymer solution. 
Accordingly, the solution prepared by the cooling dissolution method can 
be further concentrated. A plastic material such as a plastic film is 
advantageously prepared by using a polymer solution of a high 
concentration because a solvent can quickly be removed from the a polymer 
solution of a high concentration.

DETAILED DESCRIPTION OF THE INVENTION 
[Polymer and Solvent] 
A combination of a polymer and a solvent is selected preferably on a 
condition that the polymer is swelled in the solvent at a temperature of 0 
to 120.degree. C., and preferably 0 to 55.degree. C. (more preferably, a 
temperature at which the obtained solution will be used). If a polymer is 
not swelled in a solvent, it is substantially impossible to dissolve the 
polymer in the solvent even if a cooling dissolution method is used. Even 
though a polymer is dissolved in a solvent at room temperature, the 
present invention is effective because the process of the invention can 
dissolve the polymer in the solvent faster than a conventional dissolution 
method such as a method of stirring a mixture of the polymer and the 
solvent at a room temperature or an elevated temperature. 
Examples of the polymers other than cellulose esters of lower fatty acids 
include polyolefins (e.g., a norbornene polymer), polyamides (e.g., 
aromatic polyamides), polysulfones, polyethers (including 
polyethersulfones and polyetherketones), polystyrenes, polycarbonates, 
polyacrylic polymers, polyacrylamides, polymethacrylic polymers (e.g., 
polymethyl methacrylate), polymethacrylamides, polyvinyl alcohols, 
polyureas, polyesters, polyimides, polyvinyl acetates, polyvinyl acetals 
(e.g., polyvinyl formals, polyvinyl butyrals) and proteins (e.g., 
gelatin). 
In the present specification, the polyolefins mean polymers formed by an 
addition reaction of unsaturated monomers, which are essentially 
consisting of hydrocarbon. The polyamides mean polymers comprising 
repeating units combined by an amido bond (--NH--CO--). The polysulfones 
mean polymers comprising repeating units combined by a sulfonyl bond 
(--SO.sub.2 --). The polyethers mean polymers comprising repeating units 
combined by an ether bond (--O--). The polystyrenes mean polymers formed 
by an addition reaction of styrene or its derivatives (e.g., styrene 
having a substituted benzene ring). The polycarbonates mean polymers 
comprising repeating units combined by a carbonate bond (--O--CO--O--). 
The polyacrylic polymers mean polymers formed by an addition reaction of 
acrylic acid or its derivatives (e.g., acrylic esters). The 
polyacrylamides mean polymers formed by an addition reaction of acrylamide 
or its derivatives (e.g., N-substituted acrylamides). The polymethacrylic 
polymers mean polymers formed by an addition reaction of methacrylic acid 
or its derivatives (e.g., methacrylic esters). The polymethacrylamides 
mean polymers formed by an addition reaction of methacrylamide or its 
derivatives (e.g., N-substituted methacrylamides). 
Further, the polyvinyl alcohols mean polymers formed by a saponification or 
a partial saponification reaction of polyvinyl acetate (described below) 
or their derivatives (e.g., acid modified polyvinyl alcohols). The 
polyureas mean polymers comprising repeating units combined by a urea bond 
(--NH--CO--NH--). The polyesters mean polymers comprising repeating units 
combined by an ester bond (--CO--O--). The polyurethanes mean polymers 
comprising repeating units combined by a urethane bond (--NH--CO--O--). 
The polyimides mean polymers comprising repeating units combined by an 
imido bond. The polyvinyl acetates mean polyvinyl acetate and its 
derivatives. The polyvinyl acetals mean polymers formed by a condensation 
(acetal) reaction of hydroxyl of polyvinyl alcohols (described above) with 
aldehyde. The proteins include natural proteins, denatured proteins and 
partially decomposed proteins. 
The cooling dissolution method is effective in dissolving the 
above-mentioned polymers in a solvent. 
In the present invention, an organic solvent is preferred to an inorganic 
solvent. Examples of the organic solvents include ketones (e.g., acetone, 
methyl ethyl ketone, cyclohexanone), esters (e.g., methyl formate, methyl 
acetate, ethyl acetate, amyl acetate, butyl acetate), ethers (e.g., 
dioxane, dioxolane, THF, diethyl ether, methyl t-butyl ether), 
hydrocarbons (e.g., benzene, toluene, xylene, hexane) and alcohols (e.g., 
methanol, ethanol). 
A polymer is preferably swelled in a solvent, as is mentioned above. 
Accordingly, the solvent should be determined depending on the polymer. 
For example, preferred solvents of polycarbonates and polystyrenes include 
acetone and methyl acetate. Preferred solvents of polyolefins (e.g., a 
norbornene polymer) include benzene, toluene, xylene, hexane, acetone and 
methyl ethyl ketone. Preferred solvents of polyamides, polyacrylic 
polymers, polyacrylamides, polymethacrylic polymers (e.g., polymethyl 
methacrylate), polymethacrylamides, polysulfones and polyethers include 
acetone, methyl ethyl ketone, methyl acetate, butyl acetate and methanol. 
A preferred solvent of polyvinyl alcohols and proteins is water. 
Two or more solvents can be used in combination. The characteristics of the 
prepared solution (such as viscosity) can be adjusted by using two or more 
solvents in combination. 
The solvent has a boiling point preferably in the range of 20 to 
300.degree. C., more preferably in the range of 30 to 200.degree. C., 
further preferably in the range of 40 to 100.degree. C., and most 
preferably in the range of 50 to 800.degree. C. 
[Swelling Stage] 
At the first stage, a polymer is mixed with a solvent to swell the polymer 
in the solvent. 
The swelling stage is preferably conducted at a temperature of -10 to 
55.degree. C. The swelling stage is usually conducted at room temperature. 
The ratio of the polymer to the mixture is determined depending on a 
concentration of a solution to be obtained. In the case that a solvent is 
supplied to the mixture at a cooling stage (described below), the amount 
of the solvent in the mixture should be determined by subtracting the 
amount of the supplemental solvent from the amount of the solvent in a 
solution to be obtained. The amount of the polymer in the solution to be 
obtained is preferably in the range of 5 to 30 wt. %, more preferably in 
the range of 8 to 20 wt. %, and most preferably in the range of 10 to 15 
wt. %. 
The mixture of the polymer and the solvent is preferably stirred to swell 
the polymer in the solvent. The stirring time is preferably in the range 
of 10 to 150 minutes, and more preferably in the range of 20 to 120 
minutes. 
At the swelling stage, other optional additives such as a plasticizer, a 
deterioration inhibitor, a dye and an ultraviolet absorbent can be added 
to the polymer and the solvent. 
[Cooling Stage] 
At the next stage, the swelled mixture is cooled. The swelled mixture 
preferably solidifies at the cooling stage. The cooling temperature is 
preferably in the range of the temperature of 5.degree. C. higher than the 
freezing point of the solvent to the boiling point of the solvent (at 
atmospheric pressure), and more preferably in the range of the temperature 
of 10.degree. C. higher than the freezing point to the temperature of 
80.degree. C. higher than the freezing point. Accordingly, the cooling 
temperature is preferably determined by the freezing point or the boiling 
point of the solvent. The cooling temperature is usually in the range of 
-100 to -10.degree. C. 
In the first embodiment of the cooling stage, the cooling rate is in the 
range of 1 to 40.degree. C. per minute, preferably in the range of 2 to 
40.degree. C. per minute, more preferably in the range of 4 to 40.degree. 
C. per minute, and most preferably in the range of 8 to 40.degree. C. per 
minute. 
In the second embodiment of the cooling stage, the cooling rate is faster 
than 40.degree. C. per minute, preferably faster than 1.degree. C. per 
second, more preferably faster than 2.degree. C. per second, further 
preferably faster than 4.degree. C. per second, and most preferably faster 
than 8.degree. C. per second. The cooling rate is preferably fast as 
possible. However, a theoretical upper limit of the cooling rate is 
10,000.degree. C. per second, a technical upper limit is 1,000.degree. C. 
per second, and a practical upper limit is 100.degree. C. per second. 
The cooling rate means the change of temperature at the cooling stage per 
the time taken to complete the cooling stage. The change of temperature 
means the difference between the temperature at which the cooling stage is 
started and the temperature at which the cooling stage is completed. 
According to the first embodiment of the cooling stage, the swelled mixture 
is preferably cooled by incorporating the mixture into a cylinder to which 
a cooling mean is attached, and stirring and conveying the mixture in the 
cylinder. The swelled mixture can be cooled quickly according to the first 
embodiment. 
Further, the swelled mixture can also be cooled by further mixing the 
mixture with a supplemental solvent precooled at a temperature of -105 to 
-15.degree. C. The supplemental solvent is precooled preferably at a 
temperature of -100 to -25.degree. C., more preferably at a temperature of 
-95 to -35.degree. C., and most preferably at a temperature of -85 to 
-55.degree. C. 
The time taken to complete the cooling stage (the time taken to cool the 
mixture and to keep the mixture at the cooling temperature) is preferably 
in the range of 10 to 300 minutes, and more preferably in the range of 20 
to 200 minutes. 
The cylinder used in the first embodiment is preferably sealed to prevent 
contamination of water, which may be caused by dew condensation at the 
cooling stage. Further, the time taken to complete the cooling stage can 
be shortened by conducting the cooling procedures under a reduced 
pressure. A cylinder resisting pressure is preferably used to conduct the 
procedures under a reduced pressure. 
The first embodiment of the cooling stage can be conducted in a closed 
system. The closed system has an advantage (compared with an open system 
such as the second embodiment) that amounts of components used in the 
system directly reflect the composition (particularly concentration) of a 
solution to be obtained. Accordingly, the amounts of components can be 
theoretically determined from the composition of the solution to be 
obtained. On the other hand, the amounts of components should empirically 
be determined from experimental results if the solution is prepared in an 
open system. 
According to the second embodiment, the swelled mixture is cooled by 
extruding the mixture into a liquid precooled at a temperature of -100 to 
-10.degree. C. The extruded mixture is in the form of fiber having a 
diameter in the range of 0.1 to 20.0 mm or in the form of membrane having 
a thickness in the range of 0.1 to 20.0 mm. The diameter or the thickness 
is preferably in the range of 0.2 to 10.0 mm. The cooling rate is 
inversely proportional to the square of the diameter. If a thermal 
conductivity of a fibrous swelled mixture is 0.2 kcal/mhr.degree. C. and a 
temperature of a liquid is -50.degree. C., the relation between the time 
taken to cool the center of the fiber from room temperature to -45.degree. 
C. (T. second) and the diameter of the fiber (D, mm) can be represented by 
a formula, T=D.sup.2. If the diameter is 1 mm, the cooling time is 1 
second, which means the cooling rate of 70.degree. C. per second. If the 
diameter is 10 mm, the cooling time is 100 second, which means the cooling 
rate of 42.degree. C. per minute. The relation between the cooling time 
and the thickness of the membrane of the swelled mixture is the same as 
the relation between the cooling time and the diameter of the fiber. 
The fiber or the membrane of the swelled mixture can be continuous (have an 
unlimited length) or can be cut into pieces having a certain length. The 
cross sectional profile of the fibrous mixture is determined preferably to 
improve efficiency of heat transfer. Accordingly, a starlike shape is 
preferred to a circular shape because a fiber having a star-like cross 
sectional profile has a large surface area, which is effective for heat 
transfer. 
The extrusion of the swelled mixture can be conducted by applying pressure 
(including gravity) to the mixture placed on a board having many small 
holes or slits whereby the mixture passes through the holes or slits. The 
formed fibers or membranes are immersed in (usually dropped into) a 
precooled liquid. 
There is no specific limitation with respect to the liquid for cooling the 
mixture (except that it must be in the form of liquid at the cooling 
temperature). The solvent contained in the mixture can also be used as the 
liquid. Since the second embodiment is an open system, the liquid may be 
incorporated into the mixture. If the solvent of the mixture is used as 
the liquid, the composition of the obtained polymer solution could be 
analogous to the composition of the mixture. Alternatively, a polymer 
solution can contain a liquid or a substance contained in the liquid as a 
minor component by incorporating the liquid or the substance into the 
mixture. 
According to the second embodiment, the swelled solvent can be cooled in a 
short time, for example several seconds. The mixture can be held at the 
cooling temperature. The cooling time corresponds to the time for which 
the mixture passes through the precooled liquid. If the liquid flows in a 
vessel, the cooling time can be adjusted by controlling the flow rate. 
The vessel used in the second embodiment is preferably sealed to prevent 
contamination of water, which may be caused by dew condensation at the 
cooling stage. Further, the time taken to complete the cooling stage can 
be shortened by conducting the cooling procedures under a reduced 
pressure. A vessel resisting pressure is preferably used to conduct the 
procedures under a reduced pressure. 
The cooling stage of the third embodiment can be conducted in the same 
manner as in the first embodiment or the second embodiment. 
[Separating Stage] 
After the second embodiment of the cooling stage, the extruded mixture is 
preferably separated from the precooled liquid after cooling the swelled 
mixture and before warming the cooled mixture. The fiber or membrane of 
the mixture separated from the liquid can be effectively warmed at the 
next warming stage. 
The extruded mixture usually solidifies at the cooling stage. It is easy to 
separate a solid fiber or membrane from a liquid. For example, a solid 
fiber or membrane in a liquid can be taken out in a net. A board having 
small holes or slits can be used in place of the net. The net or the board 
is made of a plastic or metal that is not dissolved in a precooled liquid. 
The mesh of the net, the diameter of the hole or the width of the slit 
should be adjusted to the diameter of the fiber or the thickness of the 
membrane to prevent the fiber or membrane from passing through the net or 
the board. Further, a conveyer can separate the fiber or membrane from the 
liquid. The conveyer transports the fiber or membrane from a cooling 
device to a warming device. The conveyer can be made of a net to separate 
the fiber or membrane from the liquid effectively. 
[Warming Stage] 
According to the first and second embodiment, the cooled mixture is warmed 
to a temperature of 0 to 120.degree. C., and preferably to a temperature 
of 0 to 55.degree. C. According to the third embodiment, the cooled 
mixture is warmed to a temperature of 0 to 200.degree. C. The temperature 
of the obtained solution after the warming stage usually is room 
temperature. 
In the first embodiment of the warming stage, the warming rate is in the 
range of 1 to 40.degree. C. per minute, preferably in the range of 2 to 
40.degree. C. per minute, more preferably in the range of 4 to 40.degree. 
C. per minute, and most preferably in the range of 8 to 40.degree. C. per 
minute. 
In the second embodiment of the warming stage, the warming rate is faster 
than 40.degree. C. per minute, preferably faster than 1.degree. C. per 
second, more preferably faster than 2.degree. C. per second, further 
preferably faster than 4.degree. C. per second, and most preferably faster 
than 8.degree. C. per second. 
In the third embodiment of the warming stage, the warming rate is faster 
than 1.degree. C. per minute, preferably faster than 2.degree. C. per 
minute, more preferably faster than 4.degree. C. per minute, and most 
preferably faster than 8.degree. C. per minute. 
The warming rate is preferably fast as possible. However, a theoretical 
upper limit of the warming rate is 10,000.degree. C. per second, a 
technical upper limit is 1,000.degree. C. per second, and a practical 
upper limit is 100.degree. C. per second. 
The warming rate means the change of temperature at the warming stage per 
the time taken to complete the warming stage. The change of temperature 
means the difference between the temperature at which the warming stage is 
started and the temperature at which the warming stage is completed. 
According to the first embodiment of the warming stage, the cooled mixture 
is preferably warmed by incorporating the mixture into a cylinder to which 
a warming mean is attached, and stirring and conveying the mixture in the 
cylinder. The cooled mixture can be warmed quickly according to the first 
embodiment. 
The time taken to complete the warming stage (the time taken to warm the 
mixture and to keep the mixture at the warming temperature) is preferably 
in the range of 10 to 300 minutes, and more preferably in the range of 20 
to 200 minutes. 
The time taken to complete the warming stage can be shortened by conducting 
the warming procedures under a high pressure. A cylinder resisting 
pressure is preferably used to conduct the procedures under a high 
pressure. 
The first embodiment of the warming stage can be conducted in a closed 
system. The closed system has an advantage (compared with an open system 
such as the second embodiment), as is described about the cooling stage. 
According to the second embodiment, the cooled mixture is warmed by 
immersing the mixture in a liquid prewarmed at a temperature of 0 to 
120.degree. C. The mixture is in the form of fiber having a diameter in 
the range of 0.1 to 20.0 mm or in the form of membrane having a thickness 
in the range of 0.1 to 20.0 mm. The diameter or the thickness is 
preferably in the range of 0.2 to 10.0 mm. The relation between the 
warming time and the diameter of the fiber or the thickness of the 
membrane is analogous to the relation described about the cooling stage. 
If a mixture is extruded in the form of a fiber or membrane at the cooling 
stage by the second embodiment, the cooled fiber or membrane is immersed 
in a prewarmed liquid at the warming stage. If the cooling stage is 
conducted by procedures other than the second embodiment, a cooled mixture 
is extruded in the form of a fiber or membrane, and dropped into a 
prewarmed liquid. The mixture can be extruded in the same manner as is 
described about the second embodiment of the cooling stage. 
There is no specific limitation with respect to the liquid for warming the 
mixture (except that it must be in the form of liquid at the warming 
temperature). The solvent contained in the mixture can also be used as the 
liquid. If the process is successively conducted, the prepared polymer 
solution can be used as the prewarmed liquid. For example, the fiber or 
membrane of the mixture is dropped into the prepared solution in a vessel 
to warm the fiber or membrane quickly and to change it into the solution, 
whereby the amount of the solution is increased. The increased amount of 
the solution is recovered from the vessel. 
According to the second embodiment, the cooled mixture can be warmed in a 
short time, for example several seconds. 
The time taken to complete the warming stage can be shortened by conducting 
the warming procedures under a reduced pressure. A pressure-resistant 
vessel is preferably used to conduct the procedures under a reduced 
pressure. 
According to the third embodiment, the cooled mixture is warmed at a 
temperature of higher than the boiling point of the solvent under a 
controlled pressure of preventing the solvent from boiling. 
The warming temperature of the third embodiment is determined according to 
the boiling point of the solvent. Since preferred solvents have a boiling 
point in the range of 50 to 80.degree. C. (e.g., methyl acetate: 
57.5.degree. C., acetone: 56.5.degree. C.), the warming temperature is 
usually in the range of 60 to 200.degree. C. The warming temperature is 
preferably in the range of 70 to 180.degree. C., more preferably in the 
range of 80 to 160.degree. C., further preferably in the range of 90 to 
150.degree. C., and most preferably in the range of 100 to 140.degree. C. 
The pressure is higher than 1 atmospheric pressure (=1,0332 kgw/cm.sup.2) 
to prevent the solvent from boiling. The pressure is determined by the 
relation between the boiling point of the solvent and the warming 
temperature. The pressure is usually in the range of 1.2 to 20 
kgw/cm.sup.2, preferably in the range of 1.5 to 18 kgw/cm.sup.2, more 
preferably in the range of 2 to 16 kgw/cm.sup.2, further preferably in the 
range of 3 to 14 kgw/cm.sup.2, and most preferably in the range of 4 to 12 
kgw/cm.sup.2. 
The warming stage of the third embodiment can easily be conducted in a 
pressure-resistant sealed vessel. Where the mixture is warmed in the 
pressure-resistant sealed vessel, the solvent is gradually evaporated to 
increase the pressure i the vessel. Accordingly, the solvent is not boiled 
in the vessel, even though the temperature is higher than the boiling 
point of the solvent. The pressure is increased with increasing the 
temperature. Therefore, the pressure in the vessel is automatically 
adjusted to prevent the solvent from boiling. Further, a means for 
adjusting the pressure can be attached to a pressure-resistant vessel. For 
example, the pressure in the vessel can be increased by injecting a 
relatively inactive gas (such as nitrogen gas) into the vessel. 
The mixture may be preheated by a heater in the case that a warming 
apparatus cannot warm the mixture at a sufficient warming rate. 
After the warming stage, a polymer solution is obtained. If a polymer is 
not completely dissolved in a solvent, the procedures from the cooling 
stage to the warming stage can be repeated twice or more times. It can be 
determined by observation whether a polymer is completely dissolved in a 
solvent or not. 
[Post Treatment] 
The prepared polymer solution can be subjected to post treatment such as 
adjustment of concentration (or dilution), filtration, adjustment of 
temperature or addition of components. 
In the case that the solution is prepared by the third embodiment, the 
solution under a high pressure can easily be concentrated according to a 
flash concentration method. In the flash concentration method, the solvent 
is evaporated by reducing the high pressure to the atmospheric pressure 
immediately. 
The additional components are determined according to use of the polymer 
solution. Examples of the representative additives include a plasticizer, 
a deterioration inhibitor (e.g., a peroxide decomposer, a radical 
inhibitor, a metal inactivator, an acid scavenger), a dye and an 
ultraviolet absorbent. 
The obtained polymer solution should be stored at a temperature within a 
certain range to keep the state of the solution. The obtained polymer 
solution can be used to form various polymer materials. 
[Preparation of Polymer Film] 
A polymer film can be formed by a solvent cast method using the obtained 
polymer solution. 
The polymer solution is cast on a support, and the solvent is evaporated to 
form a film. Before casting the solution, the concentration of the 
solution is preferably so adjusted that the solid content of the solution 
is in the range of 18 to 35 wt. %. The surface of the support is 
preferably polished to give a mirror plane. A drum or a band is used as 
the support. The casting and drying stages of the solvent cast methods are 
described in U.S. Pat. Nos. 2,336,310, 2,367,603, 2,492,078, 2,492,977, 
2,492,978, 2,607,704, 2,739,069, 2,739,070, British Patent Nos. 640,731, 
736,892, Japanese Patent Publication Nos. 45(1970)-4554, 49(1974)-5614, 
Japanese Patent Provisional Publication Nos. 60(1985)-176834, 
60(1985)-203430 and 62(1987)-115035. 
[Apparatus] 
The apparatus of the present invention is described below referring to the 
drawings. 
The first embodiment of the apparatus comprises a stirring device, a 
cooling device connected to the stirring device, and a warming device 
connected to the cooling device, wherein both of the cooling device and 
the warming device include a rotary screw. 
The stirring device preferably comprises a first vessel and a stirring 
means contained in the first vessel. The cooling preferably comprising a 
second vessel (more preferably in the form of a cylinder) connected to the 
first vessel, a rotary screw contained in the second vessel and a cooling 
means attached to the second vessel. The warming device preferably 
comprises a third vessel (more preferably in the form of a cylinder) 
connected to the second vessel, a rotary screw contained in the third 
vessel and a warming means attached to the third vessel. 
FIG. 1 is a flow chart schematically illustrating the process and apparatus 
of the first embodiment. 
As is shown in FIG. 1, a polymer (P) and a solvent (S1) are introduced into 
a stirring tank (1) at the swelling stage. The polymer and the solvent are 
mixed in the tank to swell the polymer with the solvent. 
The swelled mixture is sent to a cooling device (3) by a liquid pump (2). 
The liquid pump (2) preferably is a snake pump, which is advantageously 
used to send a viscous liquid. 
The cooling device (3) comprises a cylinder connected to the stirring tank 
(1) through the liquid pump (2), a rotary screw (3-1) contained in the 
cylinder and a cooling means (3-2) attached to the cylinder. The screw 
(3-1) rotates in the cylinder to send the swelled mixture while shearing, 
mixing and cooling the mixture. The mixture cannot stay in the cylinder 
because the screw (3-1) scrapes the mixture from the inner wall of the 
cylinder. The cooling means (3-2) shown in FIG. 1 is in the form of a 
jacket of the cylinder. A refrigerant (24) flows in the jacket. The 
refrigerant is sent from a refrigerant tank (21). An example of the 
refrigerant is a mixture of methanol and water. In place of rotating the 
screw, the screw can be fixed, and the mixture can be sent through the 
screw in the cylinder by pressure. 
After cooling the swelled mixture, the refrigerant returns to the cooling 
tank (21). The medium is cooled in a refrigerator (22). A cooling tower 
(23) processes heat formed in the refrigerator. 
The cooling device (3) has a means for supplying a solvent precooled at 
-105 to -15.degree. C. A supplemental solvent (S2) is precooled in a 
cooling stock tank (19) and sent to the cylinder of the cooling device (3) 
by a liquid pump (20). The swelled mixture is cooled more quickly by 
supplying the precooled solvent (S2) to the mixture. 
The cooling device (3) is described below in more detail referring to FIG. 
2. 
The swelled mixture is quickly and uniformly cooled to -100 to -10.degree. 
C. in the cooling device. The cooled mixture is sent to a warming device 
(4). 
The warming device (4) is similar to the cooling device (3). The warming 
device (4) comprises a cylinder connected to the cooling device (3), a 
rotary screw (4-1) contained in the cylinder and a warming means (4-2) 
attached to the cylinder. The screw (4-1) rotates in the cylinder to send 
the cooled mixture while shearing, mixing and warming the mixture. The 
mixture cannot stay in the cylinder because the screw (4-1) scrapes the 
mixture from the inner wall of the cylinder. The warming means (4-2) shown 
in FIG. 1 is in the form of a jacket of the cylinder. A heating medium 
(26) flows in the warming means (4-2). The heating medium is sent from a 
constant temperature bath (27). An example of the heating medium is hot 
water. In place of rotating the screw, the screw can be fixed, and the 
mixture can be sent through the screw in the cylinder by pressure. 
A prewarmed solvent may be supplied to the cooled mixture in the same 
manner as in the cooling device. However, the supplement of the prewarmed 
solvent is not effective. The solvent lacks thermal efficiency. Heat 
formed by rotation of the screw in the warming device as well as the 
heating medium (26) warms the cooled mixture. 
After warming the cooled mixture, the heating medium and water sent from 
the cooling tower (23) exchange heat in a heat exchanger (25). The thermal 
efficiency of the apparatus is improved by the heat exchange. After the 
heat exchange, the heating medium returns to the constant temperature bath 
(27). 
The cooled mixture is quickly and uniformly warmed in the warming device to 
dissolve a polymer in a solvent. The obtained solution is sent to a heater 
(6), a filter (7) and a pressure adjusting valve (8) in the order by a 
liquid pump to adjust temperature, to conduct filtration and to adjust 
pressure. 
The solution is concentrated in a concentration tank (9). The solution, 
which has been conditioned to a high temperature and a high pressure by 
the heater (6) and the pressure adjusting valve (8) is introduced into the 
concentration tank (9) under a reduced pressure. Accordingly, the solvent 
of the solution is immediately evaporated under the reduced pressure. The 
evaporated solvent is sent to a liquefying device (18) and to the cooling 
stock tank (19). The liquefied solvent mixed with the supplemental solvent 
(S2) is again sent to the cylinder of the cooling device (3) by the pump 
(20). 
The concentrated solution is sent to a thermal controller (11) and to a 
stock tank (12) by a liquid pump (10). 
A device of the preparation of a polymer film according to a solvent 
casting method is further attached to the apparatus shown in FIG. 1. 
The solution in the stock tank (12) is sent to a filter (14) and to a slit 
die (15) by a liquid pump (13). The solution is extruded by the die, and 
cast on a band support (16). The cast solution is dried and peeled from 
the support to form a film (17). The film (17) is further dried and wound 
up to a roll. 
FIG. 2 is a sectional view schematically illustrating the cooling device (3 
in FIG. 1) of the first embodiment. 
A swelled mixture of a polymer and a solvent is introduced into a cylinder 
(35) at an inlet (31-1). A cooled mixture is sent to a warming device from 
an outlet (31-2). 
The cylinder further has an inlet of a precooled supplemental solvent (32), 
an inlet (33-1) of a refrigerant and an outlet (33-2) of the refrigerant. 
In the cylinder, a screw rotates around the center of a shaft (34). The 
screw sends the swelled mixture from the inlet (31-1) to the outlet (31-2) 
while shearing, mixing and cooling the mixture. The mixture cannot stay in 
the cylinder because the screw scrapes the mixture from the inner wall of 
the cylinder (35). 
Spiral turbulent flow fins are attached inside a cooling means (36) in the 
form of a jacket, in other words outside the cylinder (35). The fins have 
a function of improving the cooling efficiency of a refrigerant. 
The screw shaft (34) is rotated by a motor (not shown) placed outside the 
cylinder (35). The inside of the cylinder (35) is under a high pressure. 
Accordingly, the connection of the cylinder (35) to the shaft (34) is 
sealed with a sealing compound (38) and a seal stopper (39). 
The warming device (4 in FIG. 1) can be analogous to the cooling device 
shown in FIG. 2, except that the inlet of the supplemental solvent (32) is 
not necessary. 
The second embodiment of the apparatus comprises a stirring device, an 
extrusion device connected to the stirring device, a cooling device 
connected to the extrusion device and warming device connected to the 
cooling device, wherein the extrusion device is a fiber or membrane 
extruding die, and both of the cooling device and the warming device 
mainly consist of a vessel. 
The stirring device preferably comprises a first vessel and a stirring 
means contained in the first vessel (41). The cooling device preferably 
comprises a second vessel placed under the extruding device and a cooling 
means attached to the second vessel (58). The second embodiment preferably 
further comprises a separating device between the cooling device and the 
warming device. The separating device preferably comprises a conveyer, a 
part of which is placed inside the second vessel and under the extruding 
device, and the other part of which is placed outside the second vessel. 
The warming device preferably comprises a third vessel (45) placed under 
the part of the conveyer outside the second vessel and a warming means 
attached to the third vessel. 
FIG. 3 is a flow chart schematically illustrating the process and apparatus 
of the second embodiment. 
As is shown in FIG. 3, a polymer (P) and a solvent (S1) are introduced into 
a stirring vessel (41) at the swelling stage. The polymer and the solvent 
are mixed in the vessel (41) to swell the polymer with the solvent. 
The swelled mixture is sent to a fiber extruding die (43) by a liquid pump 
(42a). The liquid pump (42a) preferably is a snake pump, which is 
advantageously used to send a viscous liquid. 
The die (43) extrudes the swelled mixture in the form of a fiber. The 
fibrous swelled mixture (44) is dropped into a cooling and separating 
vessel (58). The dropped fiber is immediately cooled with a cooling liquid 
(61) in the vessel (58). 
After cooling the swelled mixture, the refrigerant returns to the cooling 
liquid tank (60) through a filter (59). A supplemental cooling liquid (S2) 
is added to the returned cooling liquid (61), and the mixed cooling liquid 
is cooled in the tank (60). The cooling liquid is sent from the tank (60) 
to the cooling and separating vessel (58) by a pump (42b). 
The cooled fibrous mixture (44) is separated from the cooling liquid (61) 
and sent to a warming vessel (45). 
Means for warming and stirring the fibrous mixture (44) are attached to the 
warming vessel (45). The vessel (45) contains a prepared polymer solution 
(50) formed by warming the fibrous cooled mixture. The polymer solution 
(50) functions as a warming liquid. The fibrous cooled mixture dropped 
into the warming vessel (45) is immediately warmed with the polymer 
solution (50) to dissolve the polymer in the solvent. 
As a result, the amount of the polymer solution (45) in the warming vessel 
(45) is increased. The extra amount of the solution is sent from the 
warming vessel (45) to a liquid pump (42c). The solution is further sent 
to a heater (46), a filter (47) and a pressure adjusting valve (48) in the 
order to adjust temperature, to conduct filtration and to adjust pressure. 
The solution is concentrated in a concentration tank (49). The solution, 
which has been conditioned to a high pressure by the pressure adjusting 
valve (48) is introduced into the concentration tank (49) under a reduced 
pressure. Accordingly, the solvent of the solution is immediately 
evaporated under the reduced pressure. The solution is further heated and 
stirred in the concentration tank. The evaporated solvent (S3) is 
recovered and reused as the solvent (S1). 
The concentrated solution is sent to a thermal controller (51) and to a 
stock tank (52) by a liquid pump (42d). 
A device of the preparation of a polymer film according to a solvent 
casting method is further attached to the apparatus shown in FIG. 3. 
The solution in the stock tank (52) is sent to a filter (54) and to a slit 
die (55) by a liquid pump (42e). The solution is extruded by the die, and 
cast on a band support (56). The cast solution is dried and peeled from 
the support to form a film (57). The film (57) is further dried and wound 
up to a roll. 
FIG. 4 is a sectional view schematically illustrating the apparatus of the 
second embodiment (3 to 5 shown in FIG. 3). 
A swelled mixture of a polymer and a solvent (71) is extruded by a fiber 
extruding die (43). The extruded fiber (44) of the mixture is dropped into 
a cooling and separating vessel (58). FIGS. 3 and 4 show only one fiber 
(44) for convenience of description. However, it is possible and preferred 
to extrude many fibers simultaneously by using an extruding die. 
The cooling and separating vessel (58) contains a cooling liquid (61). 
Further, a slanted conveyer belt made of a net (22) is placed in the 
cooling and separating vessel (58), except that the end of the belt is 
placed outside the vessel. The conveyer belt is rotated by a driving 
roller (63). 
The dropped fiber of the mixture (44) is immediately cooled with the 
cooling liquid (61) in the vessel (58). The cooled fiber (64) is separated 
from the cooling liquid (61) while conveying the fiber on the belt (62). 
The separated fiber (64) is dropped into a warming vessel (45). A guide 
board (65) and a scraper (66) are attached to the conveyer belt (62). The 
board (65) guides the dropped fiber (44) to the conveyer belt (62). The 
scraper (66) scarps the fiber adhered to the conveyer belt (62). 
An adjusting board (67) is attached to the cooling and separating vessel 
(58). The board (67) can adjust the liquid level in the vessel (58) to 
control the time for which the dropped fiber (44) is immersed in the 
cooling liquid (61). A cooling liquid (68) flowing over the board (67) is 
filtered by a filter (59 in FIG. 3) and cooled in a cooling liquid tank 
(60 in FIG. 3), and is reused as the cooling liquid (61). 
The warming vessel (45) contains a prepared polymer solution (50). The 
polymer solution is warmed and stirred in the vessel (45). The cooled 
fiber (64) dropped into the vessel (45) is immediately warmed to dissolve 
the polymer in the solvent. An extra amount of the prepared solution (69) 
is sent from the warming vessel (45) to a liquid pump (42c in FIG. 3). 
FIG. 5 is a flow chart schematically illustrating the process and apparatus 
of the third embodiment. 
As is shown in FIG. 5, a polymer (P) and a solvent (S1) are introduced into 
a stirring tank (101) at the swelling stage. The polymer and the solvent 
are mixed in the tank to swell the polymer with the solvent. 
The swelled mixture is sent to a cooling device (103) by a liquid pump 
(102a). The liquid pump (102a) preferably is a snake pump, which is 
advantageously used to send a viscous liquid. 
The cooling device (103) comprises a cylinder connected to the stirring 
tank (101) through the liquid pump (102), a rotary screw (103-1) contained 
in the cylinder and a cooling means (103-2) attached to the cylinder. The 
screw (103-1) rotates in the cylinder to send the swelled mixture while 
shearing, mixing and cooling the mixture. The mixture cannot stay in the 
cylinder because the screw (103-1) scrapes the mixture from the inner wall 
of the cylinder. The cooling means (103-2) shown in FIG. 5 is in the form 
of a jacket of the cylinder. A refrigerant (124) flows in the jacket. The 
refrigerant is sent from a refrigerant tank (121). An example of the 
refrigerant is a mixture of methanol and water. In place of rotating the 
screw, the screw can be fixed, and the mixture can be sent through the 
screw in the cylinder by pressure. 
After cooling the swelled mixture, the refrigerant returns to the cooling 
tank (121). The medium is cooled in a refrigerator (122). A cooling tower 
(123) processes heat formed in the refrigerator. 
The cooling device (103) has a means for supplying a solvent. A 
supplemental solvent (S2) is precooled in a cooling stock tank (119) and 
sent to the cylinder of the cooling device (103) by a liquid pump (120). 
The swelled mixture is cooled more quickly by supplying the precooled 
solvent (S2) to the mixture. 
The swelled mixture is quickly and uniformly cooled in the cooling device. 
The cooled mixture is sent to a warming device (104). 
The warming device (104) comprises a sealed pressure-resistant vessel. A 
heater (104-0) is placed before the warming device to preheat the mixture. 
A stirring means (4-1) is placed in the vessel. A heating means in the 
form of a jacket (104-2) is attached to the vessel. When a mixture is 
stirred in the warming device (104) while heating, the solvent is 
gradually evaporated to increase the pressure in the vessel. Accordingly, 
the solvent is not boiled, even if the mixture is heated at a temperature 
of higher than the boiling point of the solvent. 
The warming device (104) is described below in more detail referring to 
FIG. 6. 
The cooled mixture is quickly and uniformly warmed in the warming device to 
dissolve a polymer in a solvent. The obtained solution is sent by a liquid 
pump (105) to a heater (106), a filter (107) and a pressure adjusting 
valve (108) in the order to adjust temperature, to conduct filtration and 
to adjust pressure. 
The solution is concentrated in a concentration tank (109). The solution, 
which has been conditioned to a high temperature and a high pressure by 
the heater (106) and the pressure adjusting valve (108) is introduced into 
the concentration tank (109) under a reduced pressure. Accordingly, the 
solvent of the solution is immediately evaporated under the reduced 
pressure. The evaporated solvent is sent to a liquefying device (118) and 
to the cooling stock tank (119). The liquefied solvent mixed with the 
supplemental solvent (S2) is again sent to the cylinder of the cooling 
device (103) by the pump (120). 
The concentrated solution is sent to a thermal controller (111) and to a 
stock tank (112) by a liquid pump (110). 
A device of the preparation of a polymer film according to a solvent 
casting method is further attached to the apparatus shown in FIG. 5. 
The solution in the stock tank (112) is sent to a filter (114) and to a 
slit die (115) by a liquid pump (113). The solution is extruded by the 
die, and cast on a band support (116). The cast solution is dried and 
peeled from the support to form a film (117). The film (117) is further 
dried and wound up to a roll. 
FIG. 6 is a sectional view schematically illustrating the warming device 
(104 in FIG. 5) of the third embodiment. 
The pressure-resistant long vessel (104) has an inlet (141). The cooled 
mixture is introduced into the vessel (104) through the inlet (141). The 
inlet (141) is placed under a liquid surface (142) and above a steam 
jacket (143) for heating the mixture. A stirring axis (145) having many 
stirring wings (144) is centered in the vessel (104). The stirring wing 
(144) is made of a flat disc. The length of the wing is slightly shorter 
than the internal diameter of the vessel. Holes can be made in the flat 
disc. Scratching wings (146) are attached to both ends of the stirring 
wing (144). The stirring wing (144) is slowly rotated to prevent a 
vertical flow. A large opening (147) is arranged on the top of the vessel 
(104). The opening (147) is usually closed, and is opened in an emergency 
(under an extraordinary pressure). A liquid level meter (148) and a 
manometer (149) are also attached to the vessel (104). The liquid level 
(142) is adjusted between the top (150) of the stirring wing (144) and the 
inlet (141). 
A steam jacket (143) is arranged outside the vessel (104). The jacket (143) 
is divided into three parts (143a, 143b, 143c). A steam is controlled by 
controlled bulbs (151a, 151b, 151c), supplied to the jacket (143), and 
evacuated along a drain line (152). Thermometers (152a, 152b, 152c, 153a, 
153b, 153c) are attached to the top, middle and bottom of the vessel (104) 
and the top, middle and bottom jackets (143a, 143b, 143c) respectively. An 
outlet (54) is attached to the bottom of the vessel. A solution made from 
the mixture is sucked by a pump (105). 
The charge and discharge of the mixture as well as the supplement of a 
steam into the jacket can automatically be controlled in the apparatus 
shown in FIG. 6. 
REFERENCE EXAMPLE 1 
A solution of 26 weight parts of cellulose triacetate in 74 weight parts of 
acetone was prepared by using the apparatus shown in FIG. 1. At the 
swelling stage, 70 weight parts of acetone was used. The remaining 4 
weight parts of acetone was used as a supplemental solvent at the cooling 
stage. 
The obtained solution was observed to confirm that a transparent uniform 
solution was formed. 
The processing conditions are shown below. 
Temperature at the swelling stage: room temperature 
Time of the swelling stage: 30 minutes 
Cooling rate: 10.degree. C. per minute 
Temperature of supplemental solvent: -80.degree. C. 
Final cooling temperature: -75 to -65.degree. C. 
Time of the cooling stage: 60 minutes 
Warming rate: 10.degree. C. per minute 
Final warming temperature: 50.degree. C. 
Time of the warming stage: 60 minutes 
COMISON EXAMPLE 1 
A mixture of 26 weight parts of cellulose triacetate and 74 weight parts of 
acetone was stirred at 30.degree. C. for 1 hour. As a result, cellulose 
triacetate was swelled in acetone, but was scarcely dissolved in acetone. 
The swelled mixture was cooled to -70.degree. C. by using a mixture of 
methanol and dry ice. The cooling rate was 0.4.degree. C. per minute. The 
mixture was left for 2 hours at -70.degree. C. 
The cooled mixture was warmed to 50.degree. C. for 5 hours while stirring 
the mixture. The warming rate was 0.4.degree. C. per minute. The mixture 
was stirred at 50.degree. C. for 3 hours. 
As a result, most of cellulose triacetate was dissolved in acetone, however 
a part of cellulose triacetate was not dissolved in acetone and observed 
as a milky turbidity. 
REFERENCE EXAMPLE 2 
A solution of 18 weight parts of cellulose triacetate in 82 weight parts of 
methyl acetate was prepared by using the apparatus shown in FIG. 1. At the 
swelling stage, 75 weight parts of methyl acetate was used. The remaining 
7 weight parts of methyl acetate was used as a supplemental solvent at the 
cooling stage. 
The obtained solution was observed to confirm that a transparent uniform 
solution was formed. 
The processing conditions are shown below. 
Temperature at the swelling stage: room temperature 
Time of the swelling stage: 45 minutes 
Cooling rate: 12.degree. C. per minute 
Temperature of supplemental solvent: -50.degree. C. 
Final cooling temperature: -45 to -40.degree. C. 
Time of the cooling stage: 40 minutes 
Warming rate: 8.degree. C. per minute 
Final warming temperature: 50.degree. C. 
Time of the warming stage: 50 minutes 
REFERENCE EXAMPLE 3 
A solution of 18 weight parts of cellulose triacetate in 62 weight parts of 
methyl acetate and 20 weight parts of ethanol was prepared by using the 
apparatus shown in FIG. 1. At the swelling stage, 75 weight parts of the 
mixture of methyl acetate and ethanol was used. The remaining 7 weight 
parts of the mixture of methyl acetate and ethanol was used as a 
supplemental solvent at the cooling stage. 
The obtained solution was observed to confirm that a transparent uniform 
solution was formed. 
The processing conditions are shown below. 
Temperature at the swelling stage: room temperature 
Time of the swelling stage: 60 minutes 
Cooling rate: 12.degree. C. per minute 
Temperature of supplemental solvent: -50.degree. C. 
Final cooling temperature: -55 to -45.degree. C. 
Time of the cooling stage: 50 minutes 
Warming rate: 10.degree. C. per minute 
Final warming temperature: 50.degree. C. 
Time of the warming stage: 60 minutes 
REFERENCE EXAMPLE 4a 
A solution of 28 weight parts of cellulose triacetate in 72 weight parts of 
acetone was prepared by using the apparatus shown in FIGS. 3 and 4. 
The obtained solution was observed to confirm that a transparent uniform 
solution was formed. 
The processing conditions are shown below. 
Temperature at the swelling stage: room temperature 
Time of the swelling stage: 30 minutes 
Diameter of fibrous swelled mixture: 2 mm 
Number of extruded fibers: 500 
Extruded amount of swelled mixture: 20 l per minute 
Cooling rate: 15.degree. C. per second 
Temperature of cooling liquid: -80.degree. C. 
Final cooling temperature: -75 to -65.degree. C. 
Time of the cooling stage: 4 seconds 
Warming rate: 15.degree. C. per second 
Final warming temperature: 50.degree. C. 
Time of the warming stage: 20 seconds 
COMISON EXAMPLE 2 
A mixture of 28 weight parts of cellulose triacetate and 72 weight parts of 
acetone was stirred at 30.degree. C. for 1 hour. As a result, cellulose 
triacetate was swelled in acetone, but was scarcely dissolved in acetone. 
The swelled mixture was cooled to -70.degree. C. by using a mixture of 
methanol and dry ice. The cooling rate was 0.4.degree. C. per minute. The 
mixture was left for 2 hours at -70.degree. C. 
The cooled mixture was warmed to 50.degree. C. for 5 hours while stirring 
the mixture. The warming rate was 0.4.degree. C. per minute. The mixture 
was stirred at 50.degree. C. for 3 hours. 
As a result, most of cellulose triacetate was dissolved in acetone, however 
a part of cellulose triacetate was not dissolved in acetone and observed 
as a milky turbidity. 
REFERENCE EXAMPLES 4b to 12d 
The procedures of Example 4a were repeated except that the processing 
conditions were changed as is shown in Table 1 (4 to 12) and Table 2 (a to 
d) to prepare 36 (=9.times.4) polymer solutions including the solution of 
Example 4a. The conditions not shown in Tables 1 and 2 (such as the 
conditions at the swelling stage) are the same as the conditions in 
Example 4a. 
The obtained solutions were observed to confirm that transparent uniform 
solutions were formed. 
TABLE 1 
______________________________________ 
Weight 
Final cooling 
No. %* Composition of solvent 
ratio temperature 
______________________________________ 
4 28 Acetone 100 -75 to -65.degree. C. 
5 30 Methyl acetate 100 -45 to -40.degree. C. 
6 30 Methyl acetate/ethanol 
80/20 -75 to -65.degree. C. 
7 18 Methyl acetate/ethanol 
80/20 -45 to -40.degree. C. 
8 17 MeAc/ethanol/butanol 
80/15/5 
-35 to -30.degree. C. 
9 17 MeAc/butanol/acetone 
75/20/5 
-35 to -30.degree. C. 
10 17 MeAc/EtOH/cyclohexane 
80/15/5 
-35 to -30.degree. C. 
11 17 MeAc/ethanol/methanol 
80/18/2 
-35 to -30.degree. C. 
12 17 MeAc/ethanol/propanol 
80/15/5 
-35 to -30.degree. C. 
______________________________________ 
(Remark) 
%*: Concentration of polymer solution 
MeAc: Methyl acetate 
EtOH: Ethanol 
TABLE 2 
______________________________________ 
Sample 
Fibers of mixture 
Cooling stage 
Warming stage 
No. Diam. Number Amount Rate Time Rate Time 
______________________________________ 
a 2 mm 500 20 15 10 15 10 
b 2 mm 500 35 15 10 15 10 
c 5 mm 80 20 2 60 2 80 
d 5 mm 80 35 2 60 2 80 
______________________________________ 
(Remark) 
Diam.: Diameter of fibers 
Amount: Extruded amount (liter per minute) 
Rate: Cooling or warming rate (.degree. C per second) 
Time: Time of cooling or warming stage (second) 
EXAMPLE 1a 
A solution of 15.0 weight parts of polycarbonate in 85.0 weight parts of 
acetone was prepared by using the apparatus shown in FIGS. 5 and 6. 
The obtained solution was observed to confirm that a transparent uniform 
solution was formed. The solution was placed in a glass vessel having the 
diameter of 40 mm, and the light transmittance was measured. As a result, 
the transmittance at 610 nm was 45 to 50%. 
The processing conditions are shown below. 
Temperature at the swelling stage: room temperature 
Time of the swelling stage: 30 minutes 
Cooling rate: 10.degree. C. per minute 
Temperature of cooling liquid: -80.degree. C. 
Final cooling temperature: -75.degree. C. 
Warming rate: 4.degree. C. per minute 
Final warming temperature: 120.degree. C. 
Pressure at the warming temperature: 8 kgw/cm.sup.2 
COMISON EXAMPLE 11 
In 85.0 weight parts of acetone, 15.0 weight parts of polycarbonate was 
mixed. The mixture was stirred at 30.degree. C. for 2 hours. Polycarbonate 
was swelled in acetone, but not dissolved in acetone. 
EXAMPLE 1b 
In 85.0 weight parts of acetone, 15.0 weight parts of polycarbonate was 
mixed. The mixture was stirred at 30.degree. C. for 1 hour. Polycarbonate 
was swelled in acetone. 
The swelled mixture was cooled to -70.degree. C. by using a mixture of 
methanol and dry ice. The cooling rate was 0.4.degree. C. per minute. The 
mixture was left for 2 hours at -70.degree. C. 
The cooled mixture was warmed to 50.degree. C. for 5 hours while stirring 
the mixture. The warming rate was 0.4.degree. C. per minute. The mixture 
was stirred at 50.degree. C. for 3 hours. 
The obtained solution was observed to confirm that a transparent uniform 
solution was formed. The solution was placed in a glass vessel having the 
diameter of 40 mm, and the light transmittance was measured. As a result, 
the transmittance at 610 nm was 45 to 50%. 
EXAMPLE 2a 
The procedures of Example 1a were repeated except that 15.0 weight parts of 
polystyrene was used in place of 15.0 weight parts of polycarbonate to 
prepare a polymer solution. 
The obtained solution was observed to confirm that a transparent uniform 
solution was formed. The solution was placed in a glass vessel having the 
diameter of 40 mm, and the light transmittance was measured. As a result, 
the transmittance at 610 nm was 50% or more. 
COMISON EXAMPLE 12 
The procedures of Comparison Example 11 were repeated except that 15.0 
weight parts of polystyrene was used in place of 15.0 weight parts of 
polycarbonate. The mixture was stirred at 30.degree. C. for 2 hours. 
As a result, a part of polystyrene was dissolved in acetone, however most 
of polystyrene was not dissolved (swelled) in acetone. The obtained 
mixture was placed in a glass vessel having the diameter of 40 mm, and the 
light transmittance was measured. As a result, the transmittance at 610 nm 
was 45% or less. 
EXAMPLE 2b 
The procedures of Example 1b were repeated except that 15.0 weight parts of 
polystyrene was used in place of 15.0 weight parts of polycarbonate. 
As a result, polycarbonate was dissolved in acetone. The solution was 
placed in a glass vessel having the diameter of 40 mm, and the light 
transmittance was measured. As a result, the transmittance at 610 nm was 
45 to 50%. 
EXAMPLE 3a 
The procedures of Example 1a were repeated except that 15.0 weight parts of 
polymethyl methacrylate was used in place of 15.0 weight parts of 
polycarbonate to prepare a polymer solution. 
The obtained solution was observed to confirm that a transparent uniform 
solution was formed. The solution was placed in a glass vessel having the 
diameter of 40 mm, and the light transmittance was measured. As a result, 
the transmittance at 610 nm was 50% or more. 
COMISON EXAMPLE 13 
The procedures of Comparison Example 11 were repeated except that 15.0 
weight parts of polymethyl methacrylate was used in place of 15.0 weight 
parts of polycarbonate. The mixture was stirred at 30.degree. C. for 2 
hours. 
As a result, a part of polymethyl methacrylate was dissolved in acetone, 
however most of polymethyl methacrylate was not dissolved (swelled) in 
acetone. The obtained mixture was placed in a glass vessel having the 
diameter of 40 mm, and the light transmittance was measured. As a result, 
the transmittance at 610 nm was 45% or less. 
EXAMPLE 3b 
The procedures of Example 1b were repeated except that 15.0 weight parts of 
polymethyl methacrylate was used in place of 15.0 weight parts of 
polycarbonate. 
As a result, polymethyl methacrylate was dissolved in acetone. The solution 
was placed in a glass vessel having the diameter of 40 mm, and the light 
transmittance was measured. As a result, the transmittance at 610 nm was 
45 to 50%. 
EXAMPLE 4a 
The procedures of Example 3a were repeated except that 85.0 weight parts of 
methyl ethyl ketone was used in place of 85.0 weight parts of acetone to 
prepare a polymer solution. 
The obtained solution was observed to confirm that a transparent uniform 
solution was formed. The solution was placed in a glass vessel having the 
diameter of 40 mm, and the light transmittance was measured. As a result, 
the transmittance at 610 nm was 50% or more. 
COMISON EXAMPLE 14 
The procedures of Comparison Example 13 were repeated except that 85.0 
weight parts of methyl ethyl ketone was used in place of 85.0 weight parts 
of acetone. The mixture was stirred at 30.degree. C. for 2 hours. 
As a result, a part of polymethyl methacrylate was dissolved in methyl 
ethyl ketone, however most of polymethyl methacrylate was not dissolved 
(swelled) in methyl ethyl ketone. The obtained mixture was placed in a 
glass vessel having the diameter of 40 mm, and the light transmittance was 
measured. As a result, the transmittance at 610 nm was 45% or less. 
EXAMPLE 4b 
The procedures of Example 3b were repeated except that 85.0 weight parts of 
methyl ethyl ketone was used in place of 85.0 weight parts of acetone. 
As a result, polymethyl methacrylate was dissolved in methyl ethyl ketone. 
The solution was placed in a glass vessel having the diameter of 40 mm, 
and the light transmittance was measured. As a result, the transmittance 
at 610 nm was 45 to 50%. 
EXAMPLE 5 
The procedures of Example 1a were repeated except that 15.0 weight parts of 
a norbornene polymer (Artone, Japan Synthetic Rubber Co., Ltd.) was used 
in place of 15.0 weight parts of polycarbonate to prepare a polymer 
solution. 
The obtained solution was observed to confirm that a transparent uniform 
solution was formed. The solution was placed in a glass vessel having the 
diameter of 40 mm, and the light transmittance was measured. As a result, 
the transmittance at 610 nm was 50% or more. 
COMISON EXAMPLE 15 
The procedures of Comparison Example 11 were repeated except that 15.0 
weight parts of a norbornene polymer (Artone, Japan Synthetic Rubber Co., 
Ltd.) was used in place of 15.0 weight parts of polycarbonate. The mixture 
was stirred at 30.degree. C. for 2 hours. 
As a result, a part of the norbornene polymer was dissolved in acetone, 
however most of the norbornene polymer was not dissolved (swelled) in 
acetone. The obtained mixture was placed in a glass vessel having the 
diameter of 40 mm, and the light transmittance was measured. As a result, 
the transmittance at 610 nm was 40%. 
EXAMPLE 6 
The procedures of Example 1a were repeated except that 15.0 weight parts of 
an aromatic polyamide was used in place of 15.0 weight parts of 
polycarbonate, and 85.0 weight parts of butyl acetate was used in place of 
85.0 weight parts of acetone to prepare a polymer solution. 
The obtained solution was observed to confirm that a transparent uniform 
solution was formed. The solution was placed in a glass vessel having the 
diameter of 40 mm, and the light transmittance was measured. As a result, 
the transmittance at 610 nm was 50% or more. 
COMISON EXAMPLE 16 
The procedures of Comparison Example 11 were repeated except that 15.0 
weight parts of an aromatic polyamide was used in place of 15.0 weight 
parts of polycarbonate, and 85.0 weight parts of butyl acetate was used in 
place of 85.0 weight parts of acetone. The mixture was stirred at 
30.degree. C. for 2 hours. 
As a result, a part of the aromatic polyamide was dissolved in butyl 
acetate, however most of the aromatic polyamide was not dissolved 
(swelled) in butyl acetate. The obtained mixture was placed in a glass 
vessel having the diameter of 40 mm, and the light transmittance was 
measured. As a result, the transmittance at 610 nm was 45%. 
EXAMPLE 7 
The procedures of Example 1a were repeated except that 15.0 weight parts of 
polysulfone (Victolex P-350, Amoco) was used in place of 15.0 weight parts 
of polycarbonate, and 85.0 weight parts of methyl ethyl ketone was used in 
place of 85.0 weight parts of acetone to prepare a polymer solution. 
The obtained solution was observed to confirm that a transparent uniform 
solution was formed. The solution was placed in a glass vessel having the 
diameter of 40 mm, and the light transmittance was measured. As a result, 
the transmittance at 610 nm was 50% or more. 
COMISON EXAMPLE 17 
The procedures of Comparison Example 11 were repeated except that 15.0 
weight parts of polysulfone (Victolex P-350, Amoco) was used in place of 
15.0 weight parts of polycarbonate, and 85.0 weight parts of methyl ethyl 
ketone was used in place of 85.0 weight parts of acetone. The mixture was 
stirred at 30.degree. C. for 2 hours. 
As a result, a part of polysulfone was dissolved in methyl ethyl ketone, 
however most of the polysulfone was not dissolved (swelled) in methyl 
ethyl ketone. The obtained mixture was placed in a glass vessel having the 
diameter of 40 mm, and the light transmittance was measured. As a result, 
the transmittance at 610 nm was 35%. 
EXAMPLE 8 
The procedures of Example 1a were repeated except that 15.0 weight parts of 
polyethersulfone was used in place of 15.0 weight parts of polycarbonate 
to prepare a polymer solution. 
The obtained solution was observed to confirm that a transparent uniform 
solution was formed. The solution was placed in a glass vessel having the 
diameter of 40 mm, and the light transmittance was measured. As a result, 
the transmittance at 610 nm was 50% or more. 
COMISON EXAMPLE 18 
The procedures of Comparison Example 11 were repeated except that 15.0 
weight parts of polyethersulfone was used in place of 15.0 weight parts of 
polycarbonate. The mixture was stirred at 30.degree. C. for 2 hours. 
As a result, a part of polyethersulfone was dissolved in acetone, however 
most of polyethersulfone was not dissolved (swelled) in acetone. The 
obtained mixture was placed in a glass vessel having the diameter of 40 
mm, and the light transmittance was measured. As a result, the 
transmittance at 610 nm was 40%. 
EXAMPLES 9 to 19 
The procedures of Example 1a were repeated except that the polymer, the 
solvent and the cooling temperature were changed according to Table 3 to 
prepare polymer solutions. 
TABLE 3 
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Exam- Polymer Solvent Cooling 
ple (weight parts) (weight parts) 
Temp. 
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9 Polymethyl methacrylate (15.0) 
Acetone (85.0) 
-75.degree. C. 
10 Polyacrylamide (15.0) 
Acetone (85.0) 
-75.degree. C. 
11 Polymethacrylamide (15.0) 
Acetone (85.0) 
-75.degree. C. 
12 Polyvinyl alcohol (20.0) 
Water (80.0) 0.degree. C. 
13 Polyurea (15.0) Butyl acetate (85.0) 
-75.degree. C. 
14 Polyester (15.0) Butyl acetate (85.0) 
-75.degree. C. 
15 Polyurethane (15.0) 
Butyl acetate (85.0) 
-75.degree. C. 
16 Polyimide (15.0) Butyl acetate (85.0) 
-75.degree. C. 
17 Polyvinyl acetate (15.0) 
Butyl acetate (85.0) 
-75.degree. C. 
18 Polyvinyl formal (15.0) 
Butyl acetate (85.0) 
-75.degree. C. 
19 Gelatin (20.0) Water (80.0) 0.degree. C. 
______________________________________ 
The obtained solutions were observed to confirm that transparent uniform 
solutions were formed.