JP2991937B2 - Aromatic polyether sulfone solution composition and method for producing film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a solution of an aromatic polyethersulfone solution and a method for producing an aromatic polyethersulfone film useful from the solution for an optical application such as a display element or an electric / electronic device. More specifically, using a solution composition (dope) comprising 1,3-dioxolane which is a non-halogen solvent that does not cause environmental pollution, it is excellent in surface properties, transparency, uniformity, and aromatic resin with little residual solvent. The present invention relates to a solution casting method (casting method) for an ether sulfone film.

[0002]

2. Description of the Related Art In recent years, liquid crystal display devices have attracted attention because of their low power consumption and excellent image quality, and have been put to practical use. In these liquid crystal display devices,
Polymer films are used for polarizing plates, protective layers, retardation plates, electrode substrates, and the like. Among them, the polymer electrode substrate, that is, the plastic substrate, is used instead of the conventional glass substrate to reduce the weight of the liquid crystal display device, and has extremely high optical isotropy to accurately transmit the transmitted polarized light to the liquid crystal layer. And homogeneity are required. Further, heat resistance is required to withstand heat applied during processing such as film formation of a transparent electrode and formation of an alignment film. For this purpose, non-stretched polycarbonate films, polyarylate films and the like are used, but films made of aromatic polyethersulfone are considered promising because they exhibit extremely excellent properties from the viewpoint of heat resistance. However, aromatic polyethersulfone has a high polarizability due to the inclusion of an aromatic group in the molecule, and therefore has a drawback that the aromatic polyethersulfone film causes optical anisotropy even with a slight molecular orientation.
From such a viewpoint, development of a technique for forming an aromatic polyethersulfone film having excellent optical isotropy while suppressing molecular orientation as much as possible has become an important issue.

A retardation film is used for improving the visibility of an image in an STN type liquid crystal display device or a TN type liquid crystal display device, and has a role of converting elliptically polarized light transmitted through a liquid crystal layer into linearly polarized light. I am carrying it. As these materials, a polycarbonate film or a polyvinyl alcohol film that is uniaxially stretched is mainly used. Recently, from the demand for further improvement in image visibility, a retardation film having a wavelength dispersion property of a retardation that matches the liquid crystal layer has been demanded, and an aromatic polyethersulfone film is expected to be promising. As described above, the aromatic polyethersulfone has a high polarizability because it contains an aromatic group in the molecule, and the refractive index anisotropy is easily obtained by molecularly orienting the film by uniaxial stretching. Therefore, it is advantageous in that the retardation required for the retardation film can be obtained by a slight stretching, but it is difficult to obtain an optically homogeneous oriented film. In order to obtain such an oriented film, it is necessary to use a film having a high optical isotropy at the stage of an unstretched film (base film). Therefore, development of a film forming technique is desired.

In general, aromatic polyethersulfone is formed by a melt extrusion method, particularly a T-die method. The T-die method is widely used as a plastic film-forming method. However, since a high-viscosity melt is extruded, the polymer chains are easily oriented, and furthermore, stress distortion tends to remain in the film. Or homogeneity is difficult to obtain. To lower the melt viscosity, it is necessary to lower the molecular weight of the plastic or raise the film forming temperature.However, lowering the molecular weight decreases the mechanical properties of the film, and increasing the film forming temperature causes thermal degradation and coloring. Easier to trigger. Further, since the melt extruded from the T-die is directly cooled rapidly, streaks due to the T-die, that is, so-called die lines are easily generated, and it is difficult to obtain a film having a high surface property. Surface properties and optical homogeneity required for a film used for a liquid crystal display device are quite severe. For example, for a plastic substrate, a surface thickness unevenness of ± 5 μm or less, a phase difference of 10 nm or less, and an optical axis orientation of ± 10 ° or less are required.
For the base film for a retardation film, the surface thickness unevenness is ± 2 μm or less, the retardation is 30 nm or less, and the optical axis orientation is ± 1
° or less is required. In fact, it is difficult to achieve such a severe requirement by the melt extrusion method.

In order to avoid such a problem, it is conceivable to form a film by a solution casting method (casting method).
100μ like liquid crystal display film by solution casting method
A high concentration solution (dope) is required to obtain a film having a thickness of about m, but a solvent that dissolves aromatic polyether sulfone at a high concentration and is applicable to film formation is limited. For example,
Polar solvents such as dimethylacetamide, dimethylformamide, pyridine or N-methylpyrrolidone are good solvents for these. However, since these have a high boiling point, the amount of the residual solvent in the film-forming film cannot be easily reduced, and is not practical as a film-forming solvent. Halogen-based solvents such as dichloromethane and chloroform are also good solvents, but their use is banned because their effects on environmental pollution are regarded as problematic and carcinogenicity is suspected. In addition, if these solvents remain in the film even in a very small amount, there is a limitation in the application to the field of display devices and electric / electronic devices that use fine elements in order to generate undesirable corrosive compounds in the course of long-term use. . From these viewpoints, the development of a film forming technology from a non-halogen solvent is expected.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide an aromatic polyether which is excellent in surface properties, optical properties and homogeneity and has little residual solvent without using a halogen-based solvent which may cause environmental pollution or corrosion. It is an object of the present invention to provide a method for producing a sulfone film by a solution casting method.

[0007]

The present inventors have conducted intensive studies to solve the above-mentioned problems. As a result, (1) 1,3-dioxolan dissolves aromatic polyether sulfone at a high concentration, (2) It has been found that a transparent and optically isotropic smooth film can be formed from the solution having a specific viscosity without causing turbidity.

That is, the present invention provides an aromatic polyethersulfone solution composition in which 10 parts by weight of an aromatic polyethersulfone is dissolved in 15 to 90 parts by weight of a solvent containing 1,3-dioxolane of 60% by weight or more. It is.

In the present invention, when a solution composition (dope) is cast on a supporting substrate and heated to evaporate the solvent to produce a film, 1,3-dioxolane is added to the film.
For 15 to 90 parts by weight of a solvent containing 0% by weight or more, 1
A method for producing an aromatic polyethersulfone film, comprising using a dope in which 0 parts by weight of an aromatic polyethersulfone is dissolved.

As described above, 1,3-dioxolane is a very good solvent for forming an aromatic polyethersulfone film, but its only disadvantage is that peroxides are liable to be generated when exposed to air. is there. As a result of intensive studies on this point, it has been found that the generation of peroxide can be suppressed by drying in an inert gas atmosphere. Surprisingly, it has been found that even when 1,3-dioxolane is contained at a high concentration of 2.1% or more, which is the lower limit of the explosion limit, it can be dried very efficiently, and the present invention has been achieved. This means that the solvent can be efficiently recovered by a simple method by drying in an atmosphere containing 1,3-dioxolan at a high concentration.

Hereinafter, the present invention will be described in detail.

The aromatic polyethersulfone used in the present invention is a generic term for those in which an aromatic group is bonded to a skeleton by a sulfone group and an ether group. For example, the following general formulas (1) to (3)

[0013]

Embedded image (—Ar ¹ —SO ₂ —Ar ² —O—) (1) (—Ar ³ —X—Ar ⁴ —O—Ar ⁵ —SO ₂ —Ar ⁶ —O—) (2) (− Ar ⁷ —SO ₂ —Ar ⁸ —O—Ar ⁹ —O— (3) [In the formula (1), Ar ¹ and Ar ² are the same or different aromatic hydrocarbon groups having 6 to 12 carbon atoms. In the equation (2), A
r ^{3 to} Ar ⁶ are the same or different aromatic hydrocarbon groups having 6 to 12 carbon atoms, and X is a divalent hydrocarbon group having 1 to 15 carbon atoms. In the formula (3), Ar ^{7 to} Ar ⁹ are the same or different aromatic hydrocarbon groups having 6 to 12 carbon atoms. Aromatic polyether sulfone consisting of at least one kind of repeating unit selected from the group consisting of

Here, Ar ¹ , which is preferable in the formula (1),
Ar ² is an arylene group having 6 to 12 carbon atoms,
An arylene group having 6 to 10 carbon atoms is more preferable. Specific examples include an m-phenylene group, a p-phenylene group, a dimethyl-p-phenylene group, a tetramethyl-p-phenylene group, a naphthylene group and a biphenylylene group. The case where both Ar ¹ and Ar ² are p-phenylene groups is advantageous from the viewpoint of production and is particularly preferably used.

In the formula (2), preferred Ar ^{3 to} Ar ⁶
Is an arylene group having 6 to 12 carbon atoms, and an arylene group having 6 to 10 carbon atoms is more preferable. Specifically, m-phenylene group, p-phenylene group, dimethyl-
p-phenylene group, tetramethyl-p-phenylene group,
Examples thereof include a naphthylene group and a biphenylylene group, and a particularly preferable example of each of Ar ^{3 to} Ar ⁶ is a p-phenylene group. X is a divalent hydrocarbon group having 1 to 15 carbon atoms, and is selected from divalent aliphatic hydrocarbon groups having 1 to 15 carbon atoms, alicyclic hydrocarbon groups, and araalkylene groups. It is preferably a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms, an alicyclic hydrocarbon group, or an aralkylene group, and more preferably a divalent aliphatic hydrocarbon group having 1 to 10 carbon atoms. , An alicyclic hydrocarbon group and an aralkylene group. Specifically, methylene, 1,1-ethylene, 2,2-propylene, 2,2-butylene, 4-methyl-2,2-
Aliphatic hydrocarbon group such as pentylene group, 1,1-cyclohexylene group, alicyclic hydrocarbon group such as 3,3,5-trimethyl-1,1-cyclohexylene group, 1-phenyl-1,1- An aralkylene group such as an ethylene group and a diphenylmethylene group can be exemplified. Of these, the 2,2-propylene group is more preferably used. In the formula (2), particularly preferably, all of Ar ^{3 to} Ar ⁶ are p-
X is a phenylene group, and X is a 2,2-propylene group.

Further, in the formula (3), suitable Ar ⁷ ,
Ar ⁸ is an arylene group having 6 to 12 carbon atoms,
An arylene group having 6 to 10 carbon atoms is more preferable. Specific examples include m-phenylene group, p-phenylene group, dimethyl-p-phenylene group, tetramethyl-p-phenylene group, naphthylene group, biphenylylene group and the like. Among them, a p-phenylene group is more preferably used for both Ar ⁷ and Ar ⁸ . Preferred Ar ⁹ is an arylene group having 6 to 12 carbon atoms,
10 to 10 arylene groups are more preferred. In particular,
m-phenylene group, p-phenylene group, naphthylene group,
And a biphenylylene group. Among these, p-
A phenylene group and a biphenylylene group are even more preferred. In the formula (3), particularly preferably, Ar ⁷ , Ar ⁸ ,
Ar ⁹ is a p-phenylene group.

As the aromatic polyethersulfone used in the present invention, a composition or a copolymer comprising one or more kinds of repeating units represented by the above formulas (1) to (3) can also be suitably used. . For example, in the case of a copolymer, an aromatic polyether sulfone comprising a repeating unit of the formula (1) and a repeating unit of the formula (2), and an aromatic polyether comprising a repeating unit of the formula (1) and a repeating unit of the formula (3) Ether sulfone is preferably used. In that case,
The ratio of the repeating unit of the formula (1) and the repeating unit of the formula (2) or the repeating unit of the formula (1) and the repeating unit of the formula (3), that is, the copolymer composition ratio (1) / (2),
(1) / (3) may be determined in consideration of the solubility, heat resistance, and physical properties of the formed film of the obtained aromatic polyether sulfone, and is not particularly limited. Aromatic polyethersulfone containing 0.1 to 99.9 mol%, preferably 1 to 99 mol%, is preferred.

The above aromatic polyether sulfone can be polymerized by a known method. For example, it can be obtained by polycondensing a monomer having a hydroxyl group and a halogen group at the terminal in an aprotic polar solvent in the presence of an alkali metal carbonate.

The molecular weight of the aromatic polyether sulfone used in the present invention is 0.1 to 10 dl / g, preferably 0.3 to 5.
It is in the range of 0 dl / g. However, these viscosities are values measured at 30 ° C. in a 0.5 g / dl dioxolane solution. If it is less than 0.1 dl / g, a strong film cannot be obtained, and if it exceeds 10 dl / g, the polymer is not only difficult to obtain, but also the solubility is undesirably reduced.

The aromatic polyether sulfone used in the present invention is preferably subjected to reprecipitation before being dissolved in a solvent, or it is preferably used after being once melted and rapidly cooled. This is because the dissolution rate is higher in the amorphous state and the stability of the solution composition (dope) is higher. The reprecipitation is performed by dropping a dilute solution prepared using a good solvent into a poor solvent. Examples of the good solvent include polar solvents such as dimethylacetamide, dimethylformamide and N-methylpyrrolidone; halogen solvents such as dichloromethane and chloroform; and cyclic ether solvents such as 1,4-dioxane, tetrahydrofuran and 1,3-dioxolan. . Examples of the poor solvent include alcoholic solvents such as methanol and ethanol, and water. The melting is preferably performed in a nitrogen or inert gas atmosphere from the viewpoint of suppressing coloration. It is also necessary to quench as quickly as possible from the melting point to room temperature.

The main component of the solvent used in the present invention is 1,3-dioxolan. This solvent has high solubility, has a relatively low boiling point, and is suitably used as a solvent that provides a stable high-concentration solution. In addition, since it is a non-halogen solvent, there is little influence of environmental pollution or carcinogenicity which is threatened by the halogen solvent. In addition, in the case of a halogen-based solvent, for example, a corrosive gas typified by hydrogen chloride reacts with moisture in the air to generate a casting device, particularly a metal cast drum or cast belt surface which has been subjected to mirror finish which can be called a heart. When a film is formed using a solution composition comprising a halogen-based solvent, a small amount of halogen ions remaining in the film may be corroded, and a slight amount of halogen ions remaining in the film may become a transparent electrode of a liquid crystal display device or a thin film TFT.
transcriptor may deteriorate. Since 1,3-dioxolan used in the present invention is a non-halogen solvent, there is no such concern.

The solvent used in the present invention includes
More than 60% by weight of 1,3-dioxolane, preferably 7%
A solvent containing 0% by weight or more, preferably a single solvent, that is, 100% by weight of 1,3-dioxolane. The other solvent used is not particularly limited, and may be used in consideration of the effect. The effects referred to here include, for example, the improvement of the surface properties of a film formed by a solution casting method (leveling effect), the evaporation rate, and the improvement of the system by mixing solvents within a range that does not sacrifice solubility or stability. These include viscosity control and crystallization suppression effects. The type of the solvent to be mixed and the addition quality may be determined depending on the degree of these effects, and one or more kinds of the mixed solvents may be used. Suitable solvents include cyclic ethers such as 1,4-dioxane and tetrahydrofuran, hydrocarbon solvents such as toluene and xylene, ketone solvents such as acetone, methyl ethyl ketone and cyclohexanone, and ester solvents such as ethyl acetate and butyl acetate. And ether solvents such as ethylene glycol dimethyl ether and methoxyethyl acetate.

According to the present invention, the concentration of the aromatic polyethersulfone in the dope is such that the solvent amount is 15 to 90 parts by weight, preferably 20 to 50 parts by weight, based on 10 parts by weight of the aromatic polyethersulfone. . When the amount of the solvent is more than this, there is no problem in the stability of the solution, but it is not preferable because the effective concentration of the aromatic polyether sulfone is low, and when the film is formed by the solution casting method using this solution composition, Is low, external disturbance is likely to occur and surface smoothness cannot be obtained, which is not preferable. Conversely, if the amount of the solvent is less than this, it is difficult to obtain a stable dope. These concentrations are determined mainly in consideration of the stability of the dope and the viscosity of the solution.

When there is insoluble matter or suspended matter such as impurities in the obtained dope, or when haze is observed in the dope, it is desirable to remove them by a treatment such as filtration. If such treatment is not performed, the optical properties of the formed film may be deteriorated. In addition, the storage stability of the prepared dope itself may decrease.

In the present invention, a solution composition (dope) obtained by dissolving aromatic polyethersulfone in a solvent mainly comprising 1,3-dioxolane is cast on a supporting substrate, and then heated to remove the solvent. A film is obtained by evaporation. Industrial continuous film forming process generally includes a casting process, a drying process,
It consists of three heat treatment steps. The casting step is a step of smoothly casting the dope, the drying step is a step of evaporating and removing most of the solvent from the cast dope, and the heat treatment step is a step of removing the remaining solvent.

In the casting process, a method using a doctor blade, a method using a reverse roll coater, a method using extrusion from a die, and the like are used. Industrially, the most common method is to continuously extrude a dope from a die onto a belt-shaped or drum-shaped support substrate. The support substrate to be used is not particularly limited, but a glass substrate, a metal substrate of stainless steel or ferro type, a plastic film of polyethylene terephthalate or the like is used. However, a metal substrate having a mirror-finished surface is most commonly used to industrially obtain a homogeneous film having excellent optical isotropy, which is the main feature of the present invention.

In general, the solution viscosity is a very important factor in forming a transparent and smooth film from a dope. Although the solution viscosity depends on the concentration of the resin, the molecular weight and the type of the solvent, the viscosity of the solution composition of the present invention is 300 to 5
0000 cps, preferably 400 to 30,000 c
ps. Exceeding this is not preferred because the fluidity of the solution decreases and a smooth film may not be obtained. On the other hand, if it is less than this, the fluidity is too high and the surface is disturbed due to external disturbance, so that a uniform and smooth film cannot be obtained.

Before moving from the casting process to the drying step, the surface properties of the film can be highly smoothed (leveling effect) by suppressing the drying for a certain time and securing the fluidity of the dope. At this time, for example, a volatile solvent having a low boiling point, such as dichloromethane or chloroform, remarkably evaporates at room temperature. for that reason,
At the same time as the disturbance caused by evaporation occurs, the surface is dried and the so-called yuzu skin phenomenon occurs. On the other hand, 1,3-dioxolane according to the present invention has an appropriate boiling point and volatility, so that such a phenomenon is unlikely to occur, and is preferable for film formation requiring a high degree of smoothness.

In the drying step, it is necessary to evaporate and remove most of the solvent from the dope cast on the supporting substrate in as short a time as possible. However, drying conditions should be carefully selected, since rapid evaporation will cause deformation by foaming. In the present invention, the reaction is carried out in the range having the lowest boiling point among the solvents used, preferably the (boiling point −10) ° C. as an upper limit. Usually, in the initial stage, a method of sequentially or continuously raising the temperature from a temperature lower than the boiling point of the solvent used, for example, 30 ° C., is employed. Moreover, you may send a wind as needed. In that case, the wind speed is generally in the range of 1 to 20 m / sec, preferably 2 to 15 m / sec. If it is less than this, the effect is not sufficient, and if it exceeds this, it is not preferable because a smooth surface cannot be obtained due to wind disturbance. The wind speed may be changed sequentially or continuously. On the other hand, at this stage, the film is on the substrate and is peeled off from the substrate at the end of this step. At that time, if the amount of the residual solvent is large, the film is soft and the polymer flows and deforms in the film, and if the amount of the residual solvent is small, the adhesiveness to the substrate is high and stress distortion occurs. Therefore, the amount of the residual solvent is an important factor, and the amount of the residual solvent is preferably selected in the range of 5 to 30% by weight, more preferably 10 to 20% by weight.

In the heat treatment step, the film peeled from the substrate is further dried to reduce the residual solvent amount to 3% by weight or less
It is necessary to be preferably 1% by weight or less, more preferably 0.5% by weight or less. If the amount of the residual solvent is large, deformation occurs with time, or dimensional change occurs when heat is applied in a post-processing step. In particular, it is important for a liquid crystal display device because an optically uniform film is required. Industrially, a method of drying while transporting a film by a pin tender method or a roll hanging method is used. The drying temperature must be selected from a range that does not cause deformation of the film. That is, when the glass transition temperature of the aromatic polyether sulfone used is Tg (° C.), (Tg−100 ° C.)
Tg range, preferably (Tg-80 ° C) to (Tg-1
0 ° C.). Thermal deformation is less likely to occur as residual solvent decreases. Therefore, it is preferable to adopt a method of initially raising the temperature within the above range at a low temperature, and then sequentially or continuously raising the temperature. Further, air may be sent in the same manner as in the drying step.

Next, a film forming method in an inert gas atmosphere will be described.

In the present invention, the drying step, that is, the evaporation of the solvent from the dope cast on the supporting substrate is usually performed in an air atmosphere, but preferably in an inert gas atmosphere.

As the inert gas constituting the above-mentioned inert gas atmosphere, nitrogen gas, argon gas, helium gas,
Non-oxidizing and non-flammable gases such as carbon dioxide. Among them, nitrogen gas and carbon dioxide gas are preferably used in consideration of economy.

The concentration of oxygen contained in the inert gas is preferably 10% by volume or less, more preferably 8% by volume or less.
More preferably, it is at most 5% by volume. Oxygen concentration is 10
If it is higher than the capacity%, the possibility of explosion increases, which is not preferable. The oxygen concentration may satisfy the above conditions, has no technical lower limit, and may be appropriately determined in consideration of economy.

The inert gas atmosphere preferably contains a solvent having a vapor concentration of 1,3-dioxolane as a main component contained in the dope of preferably 3% by volume or more, more preferably 5% by volume or more. However, considering the recovery efficiency of the solvent, it is also desirable because the drying speed of the film is high. The upper limit concentration is not particularly limited, but is preferably 50% of the saturated vapor concentration at the drying temperature. Above that, the drying rate is undesirably reduced.

An inert gas containing a solvent vapor having such a concentration is led to a cooled condenser and the solvent is recovered in an inert gas atmosphere, whereby 1,3-dioxolan, which is easily oxidized, is converted into a peroxide. Generation can be suppressed and can be recovered stably.

In practicing the present invention, an inert gas source such as nitrogen equipped with a flow control device is connected to the air inlet of a usual dryer, and a cooling and condensing device is connected to the exhaust port, thereby making it possible to obtain a high-concentration atmosphere. From the solvent. Such a device has already been technically prepared (Japanese Patent Publication No. 55-36389, Japanese Patent Publication No. Sho 59-5959).
21656 public relations etc.).

Further, since most of the solvent is removed in the drying step, the heat treatment step corresponding to the post-drying is not necessarily performed in an inert gas atmosphere, but may be performed in air. However, it is obvious that even if the heat treatment step is performed in an inert gas atmosphere, the lower the solvent concentration in the atmosphere, the better. This step may be performed according to the above-described heat treatment step.

As described above, in the drying in an inert gas atmosphere, there is no concern about the explosion limit. Therefore, the drying can be performed in an atmosphere containing a high concentration of the solvent, and the solvent can be recovered by a simple condensation method. On the other hand, in an air atmosphere, drying must be performed in a low-concentration solvent atmosphere below the explosion limit, and only methods such as the adsorption method and gas absorption method can be applied, which is disadvantageous in terms of solvent recovery and purification. Is inevitable. In addition, drying in an inert atmosphere is advantageous because the air oxidation of the solvent does not occur, so that the generation of peroxide is suppressed. In addition, it was generally believed that the lower the concentration of the solvent vapor, the more efficiently the drying proceeded, but surprisingly, the drying proceeded smoothly even in an atmosphere having a high solvent concentration in the present invention, and the heat treatment step was included. It was found that when including the total drying, the drying could be performed at a speed not inferior to that in a low solvent concentration atmosphere in air. This is because surface drying is suppressed in the initial stage in an inert atmosphere with a high solvent concentration, and a film layer (skin layer) is formed on the surface.
It is presumed that the diffusion of the solvent in the film proceeds smoothly in the subsequent drying step and heat treatment step because no is formed.

The thickness of the film obtained according to the present invention is
It is in the range of 10 to 300 μm, preferably 50 to 200 μm. In particular, a thickness of 50 to 200 μm is preferably used for plastic substrates and retardation films. If it is thicker, it is difficult to remove the residual solvent, and if it is thinner, it is difficult to suppress thickness unevenness.

[0041]

According to the present invention, 1,3-dioxolan, which is a non-halogen solvent which does not cause environmental pollution or corrosion, is used as a main solvent to provide excellent surface properties, optical properties, homogeneity, and residual properties. An aromatic polyethersulfone film having a small amount of solvent can be obtained by a casting method. The film is useful for an optical film used for a liquid crystal display device or the like, particularly a retardation film.

[0042]

The present invention will be described below in detail with reference to examples. However, the present invention is not limited to this. The measurement items performed in the examples were measured by the following methods.

Solution viscosity: B-type viscometer B manufactured by Tokyo Keiki Co., Ltd.
Use H type. Measured at 30 ° C. Transmittance: UV-visible spectroscope (UV-2) manufactured by Shimadzu Corporation
40) was used. Haze value: An automatic digital haze meter UDH-20D manufactured by NIPPON DENSHOKU KOGYO was used. Phase difference and slow axis: KOBRA-21A automatic birefringence meter
DH (manufactured by KS Systems) was used. Quantification of residual solvent: Heating was performed at 180 ° C. for 10 hours in a nitrogen atmosphere, and the weight was measured before and after that. Quantification of peroxide: Quantified by ¹ H-NMR.

Example 1 30 parts by weight of 1,3-dioxolane were aromatic polyether sulfones mainly composed of repeating units in which Ar ¹ and Ar ² in the above formula (1) are both p-phenylene groups ( Amoco Radel A-30
0 ", ηsp / c = 0.34 dl / g) was added in three portions with stirring at room temperature to obtain a transparent and viscous dope. The solution viscosity of this solution at 30 ° C. was 4.1 × 10 ² cps. This solution did not change even when left in a closed state at room temperature for 24 hours, and neither clouding nor gelation was observed.

The resulting solution was cast on a glass substrate using a doctor blade, and then dried at 30 ° C. for 20 minutes, 50 ° C. for 20 minutes, 80 ° C. for 20 minutes, and 100 ° C. for 20 minutes to obtain a film. Peeled from the substrate. The residual solvent amount of the film in this state was 10.3% by weight. The film was further dried at 120 ° C. for 20 minutes and 150 ° C. for 14 hours, and the film thickness was measured by a stylus method to be 76 μm.
The obtained film was uniform without foaming, yuzu skin and waving phenomenon. The residual solvent was 1.22% by weight. The transmittance in the visible light region was 85% or more, the haze was 1.1%, and the film was optically transparent. Wavelength 590nm
Was 10 nm or less, and there was little variation in the film. Also, the dispersion of the slow axis was ± 10 ° or less, and it was optically homogeneous.
The glass transition point measured by DSC was 208.0 ° C., and the heat resistance was also high.

Comparative Example 1 In Example 1, instead of 1,3-dioxolane, solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, n-butanol and n-hexane were used. Could not be completely dissolved.

Example 2 A dope was prepared in the same manner as in Example 1 except that 23 parts by weight of 1,3-dioxolane was used instead of 30 parts by weight of 1,3-dioxolane in Example 1. The solution viscosity of this dope at 30 ° C. was 1.
It was 2 × 10 ³ cps. This solution did not change even when left in a closed state at room temperature for 24 hours, and neither clouding nor gelation was observed.

When a film was formed by the doctor blade method in the same manner as in Example 1, a film having a thickness of 88 μm was obtained. The obtained film was uniform without foaming, citron skin and waving. The amount of residual solvent was 1.25% by weight, which was extremely small. The transmittance in the visible light region was 85% or more, the haze was 1.1, and the film was optically transparent.
The phase difference at a wavelength of 590 nm was found to be 10 nm.
The results were as follows, and there was little variation in the film.
Also, the dispersion of the slow axis was ± 10 ° or less, and it was optically homogeneous. The glass transition point measured by DSC is
The temperature was 208.0 ° C., and the heat resistance was also high.

Example 3 A dope was prepared in the same manner as in Example 1, except that 30 parts by weight of 1,3-dioxolane in Example 1 was replaced by 20 parts by weight of 1,3-dioxolane. The solution viscosity at 30 ° C. of the dope was 2.5 × 10 ³ cps. The solution did not change even when left in a closed state at room temperature for 24 hours, and neither clouding nor gelation was observed.

When a film was formed by the doctor blade method in the same manner as in Example 1, a film having a thickness of 65 μm was obtained. The obtained film was uniform without foaming, citron skin and waving. The residual solvent amount was 0.3%, which was extremely small. The transmittance in the visible light region was 89.5%, the haze was 0.7%, and the film was optically transparent. The retardation at a wavelength of 590 nm was found to be 10 nm or less, and there was little variation within the film. Further, the dispersion of the slow axis was ± 10 ° or less, and it was optically homogeneous. The glass transition point measured by DSC is
The temperature was 219.4 ° C., and the heat resistance was also high.

Comparative Example 2 A dope was prepared in the same manner as in Example 1, except that 190 parts by weight of 1,3-dioxolan was used instead of 30 parts by weight of 1,3-dioxolan in Example 1. The dope did not change even when left in a closed state at room temperature for 24 hours, and neither clouding nor gelation was observed.

When a film was formed by the doctor blade method in the same manner as in Example 1, a film having a thickness of 9 μm was obtained. Yuzu skin-like irregularities were observed on the entire surface of this film, and the surface smoothness was not good.

Comparative Example 3 A dope was prepared in the same manner as in Example 1 except that 10 parts by weight of 1,3-dioxolan was used instead of 30 parts by weight of 1,3-dioxolan in Example 1. Stirring was continued for 24 hours, but insolubles remained. Further, 24 hours later, the whole solution became cloudy and the fluidity was significantly reduced. An attempt was made to form a film using this dope in the same manner as in Example 1, but a transparent and uniform film could not be obtained.

Example 4 Instead of 30 parts by weight of 1,3-dioxolane in Example 1, 24 parts by weight of 1,3-dioxolane were used, and aromatic polyether sulfone ("RadelA-300" manufactured by Amoco) was used. Was replaced with an aromatic polyether sulfone (“Radel A-100” manufactured by Amoco) to prepare a dope in the same manner as in Example 1. The solution viscosity of this dope at 30 ° C. was 2.8 × 10 ³ cps. This dope did not change even when left in a closed state at room temperature for 24 hours, and neither clouding nor gelation was observed.

When a film was formed by the doctor blade method in the same manner as in Example 1, an optically uniform film was obtained.

Example 5 Ar ^{3 to} Ar ⁶ in the above formula (2) are all p-phenylene groups and X is a 2,2-propylene group with respect to 40 parts by weight of 1,3-dioxolane. Aromatic polyether sulfone mainly composed of a certain repeating unit ("Udel P-1700" manufactured by Amoco, ηsp / c =
0.41 dl / g) was added in three portions while stirring at room temperature to obtain a transparent and viscous dope. The solution viscosity at 30 ° C. of this dope was 4.6 × 1.
It was 0 ² cps. The dope was filtered using a 2.5 μm pore size filter to remove suspended matter,
It was left in a closed state at room temperature for 24 hours. As a result, no change was observed in the dope, and no clouding or gelation was observed.

When a film was formed by the doctor blade method in the same manner as in Example 1, a film having a thickness of 60 μm was obtained. The obtained film was uniform without foaming, citron skin and waving. The residual solvent amount was 0.64% by weight, which was extremely small. The transmittance in the visible light region was 89% or more, the haze was 0.9, and the film was optically transparent.
The phase difference at a wavelength of 590 nm was found to be 10 nm.
The results were as follows, and there was little variation in the film.
Also, the dispersion of the slow axis was ± 10 ° or less, and it was optically homogeneous. The glass transition point measured by DSC is
The temperature was 189.0 ° C., and the heat resistance was also high.

Example 6 A dope was prepared in the same manner as in Example 5, except that 40 parts by weight of 1,3-dioxolane in Example 5 was replaced with 30 parts by weight of 1,3-dioxolane. The solution viscosity of this dope at 30 ° C. was 5.
It was 8 × 10 ³ cps.

When a film was formed by the doctor blade method in the same manner as in Example 1, a film having a thickness of 60 μm was obtained. The obtained film was uniform without foaming, citron skin and waving. The residual solvent amount was 0.2%, which was extremely small. The transmittance in the visible light region was 90.7%, the haze was 0.3%, and the film was optically transparent. The retardation at a wavelength of 590 nm was found to be 10 nm or less, and there was little variation within the film. Further, the dispersion of the slow axis was ± 10 ° or less, and it was optically homogeneous. The glass transition point measured by DSC is
The temperature was 183.3 ° C, and the heat resistance was also high.

Example 7 Instead of the aromatic polyether sulfone ("Udel P-1700" manufactured by Amoco) in Example 6, an aromatic polyether sulfone (trade name: Udel P-3500 manufactured by Amoco) was used. Thus, a dope was prepared in the same manner as in Example 5. The solution viscosity at 30 ° C. of the dope was 3.1 × 10 ³ cps.

When a film was formed by the doctor blade method in the same manner as in Example 1, an optically uniform film was obtained.

Example 8 Instead of the aromatic polyether sulfone (“Radel A-100” manufactured by Amoco) in Example 4, a repeating unit represented by the above formula (1)
A dope was prepared in the same manner as in Example 4 using a copolymer having a repeating unit ratio represented by (3) of 75/25. The solution viscosity of this dope at 30 ° C. was 2.9 ×
Was 10 ³ c ps. This dope did not change even when left in a closed state at room temperature for 24 hours, and neither clouding nor gelation was observed.

When a film was formed by the doctor blade method in the same manner as in Example 1, an optically uniform film was obtained.

[Embodiment 9]
Instead of 30 parts by weight of oxolane, use 1,3-dioxola
27 parts by weight of aromatic polyether sulfone (A
(Raco A-300 manufactured by Moco))
And the repeating unit represented by the above formula (2)
Examples using copolymers having a unit ratio of 25/75
A dope was prepared in the same manner as in Example 1. 30 of this dope
The solution viscosity at 2.2 ° C. is 2.2 × 10 ^Threecps.
Filter this dope with a 2.5 μm pore size filter.
The spent suspended matter was removed. Such dope is sealed at room temperature
No change even when left for 24 hours, and clouding and gelation
I was not able to admit.

When a film was formed by the doctor blade method in the same manner as in Example 1, an optically uniform film was obtained.

Example 10 20% by weight of 1,4-dioxane, tetrahydrofuran or cyclohexanone
Three kinds of 1,3-dioxolane solutions were prepared, and an aromatic polyethersulfone dope was prepared in the same manner as in Example 5. Each of the obtained dope solutions was transparent and viscous, did not change even when left in a closed state at room temperature for 24 hours, and neither clouding nor gelation was observed.
Using these dopes, films were formed in the same manner as in Example 1 to obtain films of about 60 μm each. All of the films were optically transparent without foaming, citron skin and waving.

Example 11 Dichloromethane 1 of aromatic polyether sulfone ("Udel P-3500" manufactured by Amoco)
A 5% by weight solution was prepared, and the solution was dropped into boiling water to perform reprecipitation. The flake-form aromatic polyethersulfone thus obtained was sufficiently dried at 150 ° C. A dope was prepared in the same manner as in Example 5 using this reprecipitated aromatic polyethersulfone instead of the aromatic polyethersulfone ("Udel P-3500" manufactured by Amoco) used in Example 7. did. The solution viscosity at 30 ° C. of this dope was 2.9 × 10 ³ cps. This dope did not change even when left in a closed state at room temperature for 48 hours, and neither clouding nor gelation was observed.

When a film was formed by the doctor blade method in the same manner as in Example 1, an optically uniform film was obtained.

Example 12 The aromatic polyethersulfone (Udel P-350 manufactured by Amoco) used in Example 7 was used.
0 ") instead of an aromatic polyethersulfone (" UdelP-3500 "manufactured by Amoco Co., Ltd.) which was melted by heating at 196 ° C. for 10 minutes in a nitrogen atmosphere and then immediately returned to room temperature.
)), And a dope was prepared in the same manner as in Example 5. The solution viscosity of this dope at 30 ° C. was 2.9 ×
Was 10 ³ c ps. This dope did not change even when left in a closed state at room temperature for 48 hours, and neither clouding nor gelation was observed.

When a film was formed by the doctor blade method in the same manner as in Example 1, an optically uniform film was obtained.

Example 13 Using the dope obtained by the method of Example 2, continuous film formation was performed. The film-forming machine was of a type extruding from a die to a mirror-finished metal belt, and a heat treatment process used a pin-tender type hot-air drying furnace. The film was formed at a speed of 1 m / min. The conditions of the drying process were 50 ° C., wind speed 2 m / sec; 50 ° C., wind speed 5 m / sec; 70 ° C., wind speed 10
m / sec. At this time, the amount of residual solvent in the obtained film was 11.5% by weight. After that, in the heat treatment process,
Hot air with an air velocity of 5 m / sec was sent to the film at 120 ° C., 150 ° C., and 170 ° C. The film thus obtained was uniform without foaming, citron skin and waving. The average film thickness was 86 μm, and the thickness unevenness was ± 3.9 μm. The transmittance was 88% and the haze value was 0.6. The phase difference was 10 nm or less, and the optical isotropy was extremely high.

Comparative Example 4 A dope was prepared in the same manner as in Example 5 except that 40 parts by weight of pyridine was used instead of 40 parts by weight of 1,3-dioxolane in Example 5. From this dope, a film was formed by the doctor blade method in the same manner as in Example 1 to obtain a film having a thickness of 103 μm. The amount of residual solvent in this film was 4.3% by weight, and it was difficult to reduce the amount of residual solvent.

Example 14 The 1,3-dioxolane solution of the aromatic polyether sulfone used in Example 1 was cast on a glass substrate, and 10% by volume of 1,3-dioxolane was dried in a drying furnace. 30 in nitrogen gas atmosphere
C. for 20 minutes, 50.degree. C. for 30 minutes, and 100.degree. C. for 20 minutes. This film was a film containing 15% by weight of the residual solvent. This film was heat-treated at 120 ° C. for 20 minutes and 150 ° C. for 14 hours under no wind conditions (in air) to obtain a film having a thickness of 82 μm. The obtained film was uniform without foaming, yuzu skin and waving phenomenon. Also,
The residual solvent was 0.55% by weight, which was lower than that of the film of Example 1 which was performed under the same conditions in an atmosphere with a low solvent concentration in air. From this fact, it has become clear that drying can be performed efficiently even in a nitrogen atmosphere containing 1,3-dioxolane.

The transmittance of the above film in the visible light region was 85% or more, the haze was 0.8%, and the film was optically transparent. The phase difference at a wavelength of 590 nm was 10 nm or less, and there was little variation within the film. Also,
The variation of the slow axis was 10 or less, and it was optically homogeneous. The glass transition temperature determined by DSC was 209 ° C., and the heat resistance was also high.

Further, 1,3-dioxolan in the drying furnace was taken out from the exhaust port and trapped at -70 ° C., and the amount of peroxide contained therein was quantified. As a result, the amount of peroxide in the used 1,3-dioxolane was 100 ppm, whereas the amount of peroxide in the recovered 1,3-dioxolane was 107 ppm. Was not generated.

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-62-25159 (JP, A) JP-A-48-73451 (JP, A) JP-A-2-105854 (JP, A) JP-A-6-205 313100 (JP, A) (58) Fields studied (Int. Cl. ⁶ , DB name) C08L 81/06 C08G 75/20-75/23 CA (STN) REGISTRY (STN)

Claims (5)

(57) [Claims] 1. An aromatic polyether sulfone solution composition in which 10 parts by weight of an aromatic polyether sulfone is dissolved in 15 to 90 parts by weight of a solvent containing 1,3-dioxolane in an amount of 60% by weight or more. 2. A solvent composition containing 60% by weight or more of 1,3-dioxolane in casting a solution composition (dope) on a supporting substrate and heating the solvent composition to evaporate the solvent. A method for producing an aromatic polyethersulfone film, comprising using a solution composition (dope) in which 10 parts by weight of an aromatic polyethersulfone is dissolved with respect to 90 parts by weight. 3. The method for producing an aromatic polyethersulfone film according to claim 2, wherein the solvent is evaporated, followed by drying in an inert gas atmosphere and heat treatment in an inert gas or air atmosphere. 4. The method for producing an aromatic polyether sulfone film according to claim 3, wherein the inert gas atmosphere contains 1,3-dioxolane in an amount of 3% by volume or more. 5. The method for producing an aromatic polyethersulfone film according to claim 3, wherein the inert gas comprises a gas mainly containing nitrogen gas and / or carbon dioxide gas having an oxygen concentration of 10% by volume or less. .