TWI460214B - A method for producing an aromatic polycarbonate film - Google Patents

Description

Method for producing aromatic polycarbonate film

In the present invention, after the polycarbonate solution is flow-molded on a support such as a metal, the support is peeled off and dried in a state containing a certain amount of a solvent, and is used for various optical materials or in place of glass. A method for forming a polycarbonate resin film having excellent optical properties and smoothness in various fields such as a substrate.

In an industrial production method such as a film by a solution process of a polycarbonate flow molding method, a metal substrate such as a steel strip is generally used as a support. The polycarbonate solution is flow-molded by extrusion molding on the support body, and a film called a tape is formed. After the solvent contained in the tape is volatilized to some extent, the support is peeled off (for example, : Patent Document 1).

On the other hand, in the production method, the solvent must be sufficiently volatilized. Therefore, the general equipment does not have to slow down the casting speed (hereinafter referred to as CS), and the productivity is poor. Further, in the case where the length of the endless belt can be increased to a high CS, strong static electricity is generated at the time of peeling, whereby the endless belt is damaged, the film is shrunk, unevenness, and minute defects are caused. Therefore, it is extremely difficult to produce a high-quality film in a long-term manner.

In the prior art, several related techniques for peeling off a film from a support are disclosed. For example, a method of adding a release agent to a polymer resin solution to facilitate peeling, coating a surface of a support with a fluororesin or the like, and reducing a peeling force of a film or the like which reduces surface energy is disclosed.

The release conditions of the film or the like of the support are mainly defined as, for example, Patent Documents 2 to 5.

Further, in Patent Document 2, it is described that the amount of the remaining solvent at the time of peeling is 10 to 30% based on the dry amount, and the surface temperature of the support is maintained at a temperature of 15.5 ° C or more at the peeling portion, and the flow of 20 ° C or less is characteristic. Plastic film method.

Patent Document 6 discloses that when the film is formed by peeling a film from a support, the film is peeled off, and when the following flow molding is performed on the support, the surface temperature of the support is 15 ° C or lower, and A flow plastic film forming method in which a gas having a low dew point in which the support body is exposed to a temperature lower than the surface temperature of the support body is satisfied.

Patent Document 7 discloses that a solution of a polymer is flow molded on a support, and when the optical polymer film is dried, the film is flow-molded, and then the support is applied to a support at a temperature of -40 ° C to 10 ° C. A method for producing an optical polymer film characterized by a drier is used to produce a film having an optically anisotropic film only in the thickness direction.

In these technologies, although copying, peeling damage, adhesion damage, scratches, surface defects, and transparency are actually improved, for example, in the case of using a glass for organic EL instead of a substrate, even if such a known technique is used It is not necessarily sufficient, and the static electricity generated by the peeling gradually damages the endless belt, so that it is difficult to stably produce a high-quality resin film for a long period of time. This problem is more prominent when it is desired to increase the thickness of the film forming film when the film forming speed is to be increased.

Patent Document 1: Japanese Patent Publication No. Hei 5-239229

Patent Document 2: Patent No. 2640189

Patent Document 3: Japanese Patent Publication No. Hei 5-239229

Patent Document 4: JP-A-2-11111

Patent Document 5: Japanese Patent Publication No. 7-304048

Patent Document 6: JP-A-2-11111

Patent Document 7: Japanese Patent Publication No. 7-304048

Therefore, in the prior art, when the tape is peeled off from the support, it is necessary to peel off under low residual solubility, so that it is extremely difficult to perform stable and continuous film formation under high CS and high CS at the time of peeling.

In order to solve the above problems, the present invention provides a flow-through film forming method of a polycarbonate film which is excellent in optical characteristics and smoothness.

The subject of the present invention has been achieved by the following constitution.

1. It is characterized in that a solvent composition of an aromatic polycarbonate containing 15 to 45% by mass is dissolved in a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 6 carbon atoms, and The ratio of the dichloromethane to the aliphatic alcohol (MA represented by the following formula (i)) is 4 to 14 and the composition of the paste is inhibited at 0 to 15 ° C in an atmosphere at a dew point, and is flow molded on the endless belt. A method for producing a stripped aromatic polycarbonate film in a state where the residual solvent concentration represented by the following formula (ii) is 35 to 45%.

Formula (i) MA = mass of aliphatic alcohol / (mass of aliphatic alcohol + mass of dichloromethane) × 100

Formula (ii) Residual solvent concentration (%) = amount of solvent / (volume amount + dissolved mass) × 100

2. A method for producing an aromatic polycarbonate film according to the first aspect of the present invention, wherein the ratio of the dichloromethane to the aliphatic alcohol (MA) is from 5 to 12.

3. A method for producing an aromatic polycarbonate film as described in the above item 1 or 2 in which the dew point of the peeling portion is controlled by being controlled in an atmosphere of 0 to 5 °C.

4. A method of producing an aromatic polycarbonate film according to any one of the above 1 to 3, wherein the time is from 120 to 270 seconds after flowing onto the endless belt to the peeling.

According to the invention of the present application, it is possible to provide a flow-through film forming method of a polycarbonate film which is excellent in optical characteristics and smoothness.

[Best form of implementation of the invention]

The best mode for carrying out the invention will be described in detail below, but the invention is not limited thereto.

The inventors of the present invention conducted a detailed study on the flow molding film, and found the following points, and completed the invention of the present application. That is, by appropriately adjusting the composition of the binder solvent, the solid concentration of the film, or controlling the temperature and humidity at the time of peeling, the film can be peeled off under high residual solubility, and the polycarbonate film having good quality under high CS can be stably produced for a long period of time. .

The method for producing an aromatic polycarbonate film of the present invention is characterized in that 15 to 45% by mass of aroma is dissolved in a solvent containing dichloromethane and a linear or branched aliphatic alcohol having 1 to 6 carbon atoms. a cement composition of a family polycarbonate, and the ratio of the dichloromethane to the aliphatic alcohol (MA represented by the following formula (i)) is 4 to 14 and the composition of the paste is suppressed to 0 to 15 ° C at a dew point. In the atmosphere, the resin is flow-molded to the endless belt, and the residual solvent concentration shown in the following formula (ii) is 35 to 45%.

Formula (i) MA = mass of aliphatic alcohol / (mass of aliphatic alcohol + mass of dichloromethane) × 100

Formula (ii) Residual solvent concentration (%) = amount of solvent / (volume amount + dissolved mass) × 100

The invention is described in detail below.

(aromatic polycarbonate)

The aromatic polycarbonate used in the present invention is not particularly limited, and is not particularly limited as long as it can obtain the aromatic polycarbonate having various properties of the desired film. Generally, a polymer material generally referred to as polycarbonate uses a polycondensation reaction in its synthesis method, generally referred to as a carbonic acid bond in the main chain, and also refers to a general phenol derivative and a polycondensation of phosgene and diphenyl carbonate. Acquired. Generally, an aromatic polycarbonate represented by a repeating unit of bisphenol component, which is called 2,2-bis(4-hydroxyphenyl)propane of bisphenol A, is preferable, and various bisphenol derivatives are appropriately selected. It can constitute an aromatic polycarbonate copolymer.

In addition to the bisphenol A as the copolymer component, such as: bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 9,9-bis(4-hydroxybenzene) , 1, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2 , 2-bis(4-hydroxyphenyl)-2-phenylethane, 2,2-bis(4-hydroxyphenyl)-1,1,1,3,3,3-hexafluoropropane, bis ( 4-hydroxyphenyl)diphenylmethane, bis(4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl)anthracene, 1,1-bis(4-hydroxyphenyl)-3,3,5 - Trimethylcyclohexane and the like.

Further, an aromatic polyester carbonate containing a terephthalic acid and/or an isophthalic acid component may also be used in part. By using a part of the constituent component of the aromatic polycarbonate formed from bisphenol A, the constituent unit can improve the properties of the aromatic polycarbonate, such as heat resistance and solubility, and the present invention It is also effective for the copolymer.

The viscosity average molecular weight of the aromatic polycarbonate used therein is preferably 10,000 or more and 200,000 or less. A particularly desirable viscosity average molecular weight is from 20,000 to 120,000. If a resin having a viscosity average molecular weight of less than 10,000 is used, the mechanical strength of the obtained film will be insufficient. Conversely, a high molecular weight of 400,000 or more will result in a problem that the viscosity of the paste is too large, which is undesirable. The viscosity average molecular weight can be measured by a commercially available high-speed liquid chromatograph or the like.

The present invention is characterized in that the ratio of dichloromethane to aliphatic alcohol (MA represented by the following formula (i)) is 4 to 14 in the solvent used for the composition of the aromatic polycarbonate solution.

Formula (i) MA = mass of aliphatic alcohol / (mass of aliphatic alcohol + mass of dichloromethane) × 100

The above ratio (MA) is preferably from 5 to 12.

The mastic composition of the present invention is composed of the methylene chloride and an aliphatic alcohol, and other solvents may be used. The other residual solvent is not particularly limited as long as it dissolves the aromatic polycarbonate in a high concentration and is miscible with the alcohol, and has a lower boiling point solvent. For example, for solvents with aromatic polycarbonate solubility: in addition to dichloromethane, such as: chloroform, 1,2-dichloroethane, 1,1,2-trichloroethane, chlorobenzene and other halogens Examples of a solvent such as a solvent, a solvent such as a 1,3-dioxolane, 1,4-dioxane or tetrahydrofuran, or a ketone-based solvent such as cyclohexanone.

When other solvents are used, it is not particularly limited, and only the effect can be considered. The effect refers to the improvement of the surface properties of the film formed by the solution flow molding method (coating effect), the evaporation rate, and the viscosity adjustment of the system, without impairing the solubility and stability. , crystallization inhibition effect, and the like. The type and amount of the solvent to be mixed may be determined in accordance with the effects of the above-mentioned effects, and one type or two or more types may be used as the mixed solvent.

Other solvents suitable for use include halogen-based solvents such as chloroform and 1,2-dichloroethane, hydrocarbon-based solvents such as toluene and xylene, ketone-based solvents such as acetone, methyl ethyl ketone and cyclohexane, and ethyl acetate. An ether-based solvent such as an ester-based solvent such as butyl acetate, ethylene glycol dimethyl ether or methoxyethyl acetate.

The type of alcohol added is limited by the solvent used. It is essential that the alcohol and the solvent have mutual solubility. These may be added alone or in combination of two or more. The alcohol of the present invention is a chain-like or branched aliphatic alcohol having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms, more preferably 2 to 4 carbon atoms. Specific examples thereof include methanol, ethanol, isopropanol, and tert-butanol. The effects of ethanol, isopropanol and tert-butanol are slightly the same, but the methanol effect is slightly lower. The reason is unclear, but it can be presumed to be the boiling point of the solvent, that is, the relationship that is easier to fly when dry. Since the above higher alcohols have a high boiling point, they are likely to remain after film formation, which is not preferable.

The amount of alcohol added must be carefully selected. These are completely lacking in solubility for aromatic polycarbonates and are extremely weak solvents. Therefore, it is not possible to add too much to obtain the minimum amount that satisfies the peelability. In general, the total amount of the solvent is preferably from 1 to 10% by mass, preferably from 1 to 8% by mass, more preferably from 1.5 to 5% by mass, and the amount of methylene chloride is adjusted to satisfy the ratio MA. The scope is appropriate.

When the amount of addition is in the range of 1 to 10% by mass, the effect of improving the solubility, the stability of the paste, and the improvement of the peelability of the polymer of the solvent becomes large.

The solution composition of the present invention may be prepared by a method in which a transparent solution having a low turbidity can be obtained. A predetermined amount of the alcohol may be added to the aromatic polycarbonate solution dissolved in a solvent in advance, or the aromatic polycarbonate may be dissolved in the alcohol-containing mixed solvent. However, as described above, since the alcohol is a weak solvent, in the method of adding the former, the gel may be cloudy after the precipitation of the polymer, so that the latter method of dissolving the solvent is preferred.

The aromatic polycarbonate solution composition (slurry) of the present invention depends on the molecular weight of the cosolvent or aromatic polycarbonate used therein, and the solvent is contained in an amount of 15 to 45% by mass of the aromatic polycarbonate. The amount is preferably 15 to 55% by mass, more preferably 20 to 50% by mass. When the amount of the solvent exceeds this time, the stability of the solution is not problematic, but the effective concentration of the aromatic polycarbonate becomes low. Therefore, when the solution composition is used to form a film by a solution flow molding method, since the solution viscosity is low, It is easy to cause external interference, and it is not easy to obtain surface smoothness. On the other hand, if the amount of the solvent does not reach this point, it is difficult to obtain a stable paste. These concentrations are mainly determined by considering the stability of the glue and the viscosity of the solution.

In the present invention, after the aromatic polycarbonate solution composition (slurry) is flow-molded on the support substrate, the film is obtained by evaporation of the solvent. The solvent can be evaporated by heating. The industrial continuous film forming step usually consists of three steps of a flow molding step, a pre-drying step, and a post-drying step. The flow molding step is a step of smoothing the flow of the glue. The pre-drying step is a step of removing a large portion of the solvent by a flow molding glue, and the post-drying step is a step of removing the residual solvent.

In the flow molding step, a method of extrusion by a mold, a method by a doctor blade, a method of reverse roll coating, or the like is used. Industrially, the method of continuously extruding the glue on a belt-shaped or cylindrical support substrate by a mold is the most common. Examples of the support substrate to be used include a glass substrate, a metal substrate such as stainless steel or iron, and a plastic substrate such as polyethylene terephthalate. The material and surface state of the support substrate greatly affect the peelability of the flow-through film. For example, in a substrate coated with Teflon (registered trademark) having a very low surface tension, the peeling property is good. However, when a film having a high degree of surface properties and optical homogeneity is industrially continuously formed, the most common one is a metal substrate whose surface is mirror-finished, and the present invention determines the effect by using such a metal substrate.

The viscosity of the solution at the time of film formation of a transparent and smooth film by a paste is a very important factor. The solution viscosity depends on the concentration of the polymer, the molecular weight and the type of the solvent, and the viscosity of the solution composition of the present invention is preferably from 500 to 50,000 cps, preferably from 700 to 30,000 cps. When it exceeds this range, the fluidity of the solution is lowered, and it is not preferable to obtain a smooth film. Moreover, when the fluidity is too high when the range is not reached, the T-die used for general casting is not easy to uniformly discharge the glue, and external disturbance causes the surface to be disordered, and a homogeneous and smooth film cannot be obtained. The effect of adding alcohol on the viscosity of the solution is also only a trace amount.

The temperature at which the flow molding of the present invention is carried out depends on the solvent to be used, and is usually carried out at a temperature of from 10 to 40 ° C, preferably from 15 to 35 ° C. In order to obtain a film having good smoothness, it is necessary to melt and smooth the solution extruded from the mold on the support substrate. If the flow molding temperature is too high at this time, the surface is dried and solidified before being smoothed. On the other hand, if the temperature is too low, the viscosity of the fluid solution is lowered after cooling, and it is difficult to obtain smoothness and unfavorable condensation.

The humidity of the flow molding of the present invention is characterized in that the dew point is controlled in an atmosphere of 0 to 15 ° C, and the fluid is molded on an endless belt. Preferably it is 0 to 5 °C. By controlling the dew point in this range, a polycarbonate film having excellent peelability, excellent optical properties, and smoothness can be obtained. When the film is formed in an atmosphere in which the dew point exceeds 15 ° C, water droplets adhering to the surface adhere to the surface, which deteriorates smoothness, and causes generation of garbage and foreign matter. Further, in an atmosphere exceeding 20 ° C, whitening occurs due to condensation on the surface, and further than 25 ° C, the film is whitened in general, and the film is broken at the time of peeling.

When the dew point is controlled, the flow molding step can also be made into one zone or divided into a plurality of zones for control. In particular, it is preferable to blow dry air around the peeling portion, or to form an independent region around the peeling portion, and to control the dew point.

By moving from the flow molding step to the drying step, after a certain period of time is suppressed from drying, the surface properties of the film can be highly smoothed (smoothing effect) by ensuring the fluidity of the paste.

In the pre-drying step, it is necessary to evaporate the majority of the solvent by evaporation of the paste flowing on the support substrate in the shortest possible time. However, if violent evaporation occurs, deformation occurs via foaming, so it is necessary to carefully select drying conditions. In the present invention, the lowest boiling point of the solvent to be used is preferably such that the (boiling point - 5 ° C) is made into an upper limit range and drying is started. After that, the temperature is gradually or continuously increased, and it is necessary to increase the drying efficiency. The upper limit of the temperature in the final stage of the step is preferably 120 ° C, preferably 100 ° C. In this step, when the residual solvent is in the present invention, it also contains 35 to 45% by mass, and when the temperature is too high, foaming is not preferable. Also, if necessary, you can also send the wind. In this case, the wind speed is usually 20 m/sec or less, preferably 15 m/sec or less. Beyond this range, wind interference does not make it impossible to obtain a smooth surface. The wind speed may be enhanced by stages or continuity, and it is better to say that it is better. In the initial stage, in order to avoid wind interference, there is no wind.

In the pre-drying step, the film is attached to the substrate, and at the end of the step, the substrate is peeled off. In this case, if the amount of the remaining solvent is large, the film is soft and deformed. On the other hand, even if the residual solvent is small, even if the fluidized film cast from the solution composition of the present invention has high adhesion to the support substrate, the peeling property is deteriorated. Stress deformation, peeling line, and peeling damage occur. Therefore, the amount of the residual solvent is an important factor, and it is preferable that the amount of the residual solvent represented by the following formula (ii) is selected from the range of 35 to 45% by mass.

Formula (ii) Residual solvent concentration (%) = amount of solvent / (volume amount + dissolved mass) × 100

In the solution flow molding method using a metal substrate, the peeling property is usually good at the initial stage of film formation, and the peeling property is gradually lowered in the case of repeated peeling. The reason for this is not certain, and it is presumed that a large amount of metal atoms having a high surface tension are exposed gradually on the surface of the substrate, or a very small amount of the polymer adheres to the surface, which starts to function like an adhesive layer. As a countermeasure, the surface of the substrate is periodically cleaned, for example, the surface of the substrate is wiped with water, and the peeling property is restored. However, in the industrial continuous film forming step, the work is extremely troublesome and the efficiency is poor. If this operation is not required in accordance with the present invention, good peelability of the flow-through film from the support substrate can be effectively maintained.

In the post-drying step, the film peeled off from the substrate is further dried, and the amount of the residual solvent is preferably 3% by mass or less, preferably 1% by mass or less, and more preferably 0.5% by mass or less. When the amount of the residual solvent is large, deformation occurs over time, or after the processing step such as a liquid crystal display device, if heated, dimensional change, that is, heat shrinkage is caused. Usually, the post-drying step is carried out in the industry by means of a needle combing method or a roll hanging method, and the film is conveyed while drying. However, in these methods, various forces are added to the film during drying. Therefore, in the film formation of a film which requires optically high homogeneity, such as the use of a liquid crystal display device, the drying temperature must be selected from the range in which film deformation does not occur. In general, when the glass transition temperature of the aromatic polycarbonate to be used is Tg (°C), the range of (Tg - 120 ° C) to Tg is preferably selected, and preferably (Tg - 100 ° C) - (Tg - 10) °C) range. Exceeding this range will cause thermal deformation of the film to be unsatisfactory. If the range is not reached, the drying speed will be significantly slower. Thermal deformation will not easily occur if the residual solvent is reduced. Therefore, in this range, it is preferable that the initial stage is a low temperature, and then the temperature is raised stepwise or continuously. In the post-drying step, the air may be supplied in the same manner as the pre-drying step.

In the present invention, when the aromatic polycarbonate film is produced, it may be dried in an inert gas atmosphere such as nitrogen or carbonic acid gas at a high solvent gas concentration. When a flammable solvent is used, the bursting limit of the solvent is considered, and it is preferable to use a drying method in the inert gas atmosphere from the viewpoint of safety. At this time, the gas concentration of the solvent considers the heat energy of drying, and the recovery efficiency is preferably 3% by volume or more. Further, in an inert gas atmosphere, the oxygen concentration is preferably 10% by volume or less.

The thickness of the film of the present invention is preferably from 10 to 300 μm, preferably from 50 to 200 μm. In particular, it is preferable to use a plastic substrate constituting the display device and a thickness of 50 to 200 μm for the film for a phase difference film. If it is higher than this thickness, it is difficult to remove the residual solvent, and below this thickness, it is difficult to suppress thickness unevenness.

(display device)

By using the aromatic polycarbonate film produced by the present invention, various display devices having good visibility can be produced. The aromatic polycarbonate film of the present invention uses various types of reflective, light-transmitting, translucent LCD or TN type, STN type, OCB type, HAN type, VA type (PVA type, MVA type), IPS type, and the like. The LCD driver should be suitable. Further, the aromatic polycarbonate film of the present invention is also suitable for use in various display devices such as a plasma display, a field emission display, an organic EL display, an inorganic EL display, and an electronic paper having good planarity.

(Organic EL device)

An organic EL (electroluminescence) element which is particularly suitable for the aromatic polycarbonate film of the present invention will be described.

The organic EL element is provided with a transparent electrode on both sides of the substrate, and a composite layer which is laminated by a layer having various functions such as (a) injection function, (b) conveyor function, and (c) luminescence function is interposed therebetween. The resulting organic EL element layer is sealed around. When constituting the organic EL device, for example, a substrate of an aromatic polycarbonate film (including a patterned transparent conductive layer auxiliary electrode layer)/hole injection layer/hole transport layer/light emitting layer/electron injection layer/ An example of a layer formed by a cathode/seal layer. The layer configuration is not particularly limited, and specifically, it can correspond to an anode/light emitting layer/cathode, an anode/hole injection layer/light emitting layer/cathode, an anode/light emitting layer/electron injection layer/cathode, and an anode/hole injection layer. /Layer layer / electron injection layer / cathode, anode / hole injection layer / hole transport layer / light-emitting layer / electron transport layer / electron injection layer / cathode and many other layer structures. It is not limited to this configuration, and is accompanied by a color filter or a plurality of means (layers) other than the color filter. The organic EL device may use a glass substrate as a substrate, and the aromatic polycarbonate film of the present invention may be applied to the outside of the glass substrate, or the glass substrate may be replaced by the aromatic polycarbonate film of the present invention. When the substrate is replaced by the aromatic polycarbonate film of the present invention, the whole can be made into a flexible display.

[Examples]

The following examples are given to illustrate the invention, but the invention is not limited thereto.

<Polycarbonate resin used>

‧Elderly Chemicals (shares) panliteL-1225Y

‧Emperor Chemicals (shares) panliteK-1300Y

‧Copolymer A: BCF (9,9-bis-(3-methyl-4-hydroxyphenyl)fluorene) as a monomer and BPA (2,2-bis-(4-hydroxyphenyl)-propane ) copolymerized with BCF30 mol%/BPA70 mol% (Tg195°C)

‧Copolymer B: BCF (9,9-bis-(3-methyl-4-hydroxyphenyl)fluorene) as a monomer and BPA (2,2-bis-(4-hydroxyphenyl)-propane ) copolymerized with BCF70 mol%/BPA30 mol% (Tg230 °C)

The aromatic polycarbonate film of the present invention and comparatively produced was produced by the following production.

[Example 1]

For 65 parts by mass of a mixed solvent of dichloromethane and ethanol containing 3.3 parts by mass of ethanol, 35 parts by mass of a polycarbonate resin having a bisphenol A as a constituent unit (Teijin Chemicals panlite L-1225Y) is 25 Stirring was carried out at ° C, and after dissolution, a transparent viscous paste was obtained. The glue was subjected to air supply by dry air, and flow-molded on a stainless steel belt having a dew point of 7 ° C or less, and peeled off after 220 seconds. The residual solvent at this time was 42% by mass. As a result of good peelability and low static electricity, no peeling section, peeling line, or the like appeared on the surface of the film which was visually observed. The residual solvent concentration is dried to 1% by mass or less. The film thickness was 115 μm.

[Embodiment 2]

For 70 parts by mass of a mixed solvent of methylene chloride and ethanol containing 8.4 parts by mass of ethanol, 30 parts by mass of a polycarbonate resin (Teijin Chemicals panlite K-1300Y) having bisphenol A as a constituent unit was used in 25 parts. Stir at ° C while dissolving to obtain a clear, viscous paste. After the glue is sent to the air by dry air, it is flow-molded on a stainless steel belt with a dew point of 5 ° C or less, and the dehumidifier is opened after the stripping portion is further batched, so that the dew point is below 3 ° C, and after 200 seconds. Stripped. The residual solvent at this time was 42% by mass. As a result of good peelability and low static electricity, no peeling section, peeling line, or the like appeared on the surface of the film by visual observation. The drying is carried out until the residual solvent concentration is 1% by mass or less. The film thickness was 114 μm.

[Example 3]

For 68 parts by mass of a mixed solvent of dichloromethane and ethanol containing 2.7 parts by mass of ethanol, 32 parts by mass of a copolymerized polycarbonate resin (copolymer A) containing bisphenol A was stirred at 25 ° C while being dissolved. Obtain a transparent sticky glue. The glue was subjected to air supply by dry air, and flow-molded on a stainless steel belt having a dew point of 10 ° C or less, and peeled off after 250 seconds. The residual solvent at this time was 40% by mass. As a result of good peelability and low static electricity, no peeling section, peeling line, or the like appeared on the surface of the film by visual observation. It is dried until the residual solvent concentration is 1% by mass or less. The film thickness was 125 μm.

[Example 4]

37 parts by mass of a copolymerized polycarbonate resin (copolymer B) containing bisphenol A was stirred at 25 ° C while dissolving 63 parts by mass of a mixed solvent of dichloromethane and ethanol containing 4.4 parts by mass of ethanol , to obtain a transparent sticky glue. The glue was subjected to air supply by dry air, and flow-molded on a stainless steel belt having a dew point of 8 ° C or less, and the residual solvent was peeled off at 42% by mass. The time from flow molding to peeling was 130 seconds. As a result of good peelability and low static electricity, no peeling section, peeling line, or the like appeared on the surface of the film by visual observation. It is dried until the residual solvent concentration is 1% by mass or less. The film thickness was 85 μm.

[Examples 5 to 13]

The aromatic polycarbonate film of Examples 5 to 13 was produced in the same manner as in Example 1 except that the polycarbonate resin, the solvent, the MA, the dew point, the residual solvent, and the time from the extension to the peeling and the film thickness were changed as shown in Table 1.

[Comparative Example 1]

For 90 parts by mass of a mixed solvent of dichloromethane and ethanol containing 5.4 parts by mass of ethanol, 10 parts by mass of a polycarbonate resin having a bisphenol A as a constituent unit (Teijin Panlite K-1300Y) was used. Stirring was carried out at 25 ° C while dissolving to obtain a transparent viscous paste. The glue was subjected to air supply by dry air, and flow-molded on a stainless steel belt having a dew point of 10 ° C or less, and peeled off after 300 seconds. The residual solvent at this time was 40% by mass. The film thickness was 115 μm. As a result, the solid content is small, so the time until the peeling is extremely long, and the production efficiency is remarkably lowered. Moreover, since the concentration of the glue is low, the viscosity is low, and when the flow molding is performed, the surface is wrinkled, the surface of the protruding pomelo-like surface is poor, and the turbidity is high.

[Comparative Example 2]

For 50 parts by mass of a mixed solvent of dichloromethane and ethanol containing 2 parts by mass of ethanol, 50 parts by mass of a polycarbonate resin containing bisphenol A as a constituent unit (Teijin Chemicals panlile L-1225Y) is used. Stirring at 25 ° C, while dissolving, the viscosity of the glue is too high to solidify, so it cannot be flow molded on the stainless steel belt, and the film cannot be formed.

[Comparative Example 3]

30 parts by mass of a copolymerized polycarbonate resin (copolymer A) containing bisphenol A was stirred at 25 ° C while dissolving 70 parts by mass of a mixed solvent of dichloromethane and ethanol containing 9.8 parts by mass of ethanol , to obtain a transparent sticky glue. The paste was ventilated by dry nitrogen gas and cast on the stripped stainless steel strip at a dew point of 0 degrees or less, and peeled off after 230 seconds. At this time, the residual solvent was 43% by mass. As a result, the peeling property was good, and no peeling section, a peeling line, etc. were formed in the film surface. However, since the dew point is lowered too much, the electrification becomes large, discharge occurs between the film rolls, and protrusions on the surface of the film deteriorate the flatness of the surface. It is dried until the residual solvent concentration is 1% by mass or less. The film thickness was 116 μm.

[Comparative Example 4]

30 parts by mass of a copolymerized polycarbonate resin (copolymer B) containing bisphenol A was stirred at 25 ° C while dissolving 70 parts by mass of a mixed solvent of dichloromethane and ethanol containing 7 parts by mass of ethanol After that, a transparent viscous glue is obtained. The paste was flow-molded on a stainless steel belt, and at a temperature not exceeding 15 ° C of the uncontrolled dew point, peeling was performed 210 seconds later. At this time, the residual solvent was 41% by mass. As a result, the peeling property was good, and no peeling section, a peeling line, etc. were formed in the film surface. However, the dew point is too high, causing the film surface of the film to evaporate via methylene chloride during peeling, condensation under the influence of latent heat, and white turbidity in the presence of voids in the film. The drying is carried out until the residual solvent concentration is 1% by mass or less. The film thickness was 110 μm.

[Comparative Example 5]

For 70 parts by mass of a mixed solvent of dichloromethane and ethanol containing 5.6 parts by mass of ethanol, 30 parts by mass of a polycarbonate resin having a bisphenol A as a constituent unit (Teijin Panlite L-1225Y), After stirring at 25 ° C and simultaneously dissolving, a clear viscous paste was obtained. After the slurry was subjected to air supply by dry air, it was flow-molded on a stainless steel belt under an atmosphere having a dew point of 7 ° C, and peeled off after 300 seconds. At this time, the residual solvent was 20% by mass. Since the residual solvent at the time of peeling was a small value of 20% by mass, static electricity was generated at the time of peeling, and a peeling section, a peeling line, and the like were visually observed on the surface of the film. The residual solvent concentration is dried to 1% by mass or less. The film thickness was 120 μm.

[Comparative Example 6]

For 70 parts by mass of a mixed solvent of dichloromethane and ethanol containing 3.5 parts by mass of ethanol, 30 parts by mass of a polycarbonate resin having a bisphenol A as a constituent unit (Teijin Panlite L-1225Y), After stirring at 25 ° C and simultaneously dissolving, a clear viscous paste was obtained. The mortar was subjected to air supply in a dry air, and flow-molded on a stainless steel belt under an atmosphere having a dew point of 6 ° C, and peeled off after 100 seconds. At this time, the residual solvent was 53% by mass. As a result, it was broken at the time of peeling, and a film could not be produced

[Comparative Example 7]

30 parts by mass of a copolymerized polycarbonate resin (copolymer A) containing bisphenol A was stirred at 25 ° C while dissolving 70 parts by mass of a mixed solvent of dichloromethane and ethanol containing 1.4 parts by mass of ethanol. , to obtain a transparent sticky glue. The glue was subjected to air supply by dry air, and flow-molded on a stainless steel belt under an atmosphere having a dew point of 7 ° C, and peeling was performed after 230 seconds. The residual solvent at this time was 42% by mass. However, since the ratio of ethanol is a small value of 2% by mass, the tension for peeling is extremely large, and a peeling section, a peeling line, and the like appear on the film by visual observation. The drying is carried out until the residual solvent concentration is 1% by mass or less. The film thickness was 114 μm.

[Comparative Example 8]

For 70 parts by mass of a mixed solvent of dichloromethane and ethanol containing 11.2 parts by mass of ethanol, 30 parts by mass of the bisphenol A-containing polycarbonate resin (copolymer B) was stirred and dissolved at 25 ° C, Obtain a clear, viscous paste. The paste was subjected to air supply by dry air, and flow-molded on a stainless steel belt under an atmosphere having a dew point of 7 ° C, and peeled off after 200 seconds. The residual solvent at this time was 42% by mass. However, since the proportion of ethanol is as high as 16% by mass, condensation is apparent at the time of peeling, and the cavity is opened and turbid on the belt surface of the film. The film thickness was 112 μm.

[Comparative Examples 9, 10]

The polycarbonate resin, the solvent, the MA, the dew point, the residual solvent, the time from the extension to the peeling, and the film thickness as described in Table 1 were prepared in the same manner as in Comparative Example 1, and the aromatic polycarbonate film of Comparative Examples 9 and 10 was produced. .

The composition, production conditions, productivity evaluation, surface roughness (Ra), and haze of the aromatic polycarbonate film sample were as follows in Table 1 below.

In addition, the following evaluations were made for productivity evaluation, surface roughness (Ra), and turbidity.

(productive)

○: No fault, high defect productivity

△: Slightly faulty, defective and less productive

×: fault, defect, and poor productivity

(surface roughness (Ra))

The surface roughness (Ra) was measured by an optical interference type surface roughness meter RST/PLUS (manufactured by WYKO Co., Ltd.) in accordance with JIS B 0601:2001.

(turbidity)

One film sample was measured by T-2600DA manufactured by Tokyo Denshoku Industries Co., Ltd. according to ASTM-D1003-52.

The aromatic polycarbonate film samples of Examples 1 to 13 of the present invention showed good productivity, surface roughness (Ra), and turbidity.

Next, the aromatic polycarbonate film produced in Examples 1 to 13 and Comparative Examples 1 to 10 (except Comparative Examples 2 and 6 in which the film could not be produced) was used as a plastic substrate, and a transparent conductive layer (ITO) was formed. An organic EL (electroluminescence) element was fabricated on a transparent conductive film.

On the polycarbonate film of 100 nm imparted to the ITO conductive layer, CuPc (10 nm) / NPO (30 nm) / CBP: Ir (ppy) 33% by mass / Alq ₃ (50 nm) / LiF (0.5 nm) / Al (120 nm) In the order, the hole injection layer, the hole transport layer, the light-emitting layer, the electron transport layer, and the electrode were formed by vacuum deposition, and finally sealed in an atmosphere of N ₂ gas.

<Evaluation of Organic EL>

(uneven illumination)

The source major unit Model 2400 manufactured by KEITHLEY was used to emit light after applying a DC voltage to the organic EL element. The unevenness of light emission was observed with a microscope at 50 times for a light-emitting element that emits light at 200 cd.

Evaluation of unevenness in illuminance

◎: 90% or more uniform illumination

○: More than 80% of uniform light

△: 70% or more uniform illumination

×: Only 70% have uniform illumination

(display defect)

The organic EL element was caused to emit light, and the area of the defective portion displayed during white display was evaluated in accordance with the following order.

◎: No display defects at all

○: Display defects appear in areas that are less than 1%

△: Display defects appear in areas where 1% or more are less than 3%

×: Display defects appear in an area of 3% or more

(voltage rise)

When driving at a specific current of 10 mA/cm ² , the initial voltage and the voltage after 150 hours were measured. The relative value of the voltage after 100 hours from the initial voltage was used as the voltage increase rate, and was classified into the following order.

◎: 100～105

○: 106 to 115

△: 116 to 125

×: 125 or more

(lower brightness)

The time required for the luminance to fall to 90% of the initial luminance was measured, which was used as the 10% decay time (τ 0.9) for the deterioration index at the initial stage of the device. As a result, the relative value of Example 1 was 100, and it was divided into the following order.

◎: 100

○: 90 to 99

△: 80 to 89

×: 79 or less

(black dot)

Each of the organic EL devices was stored in an environment of 60 ° C and 90% RH for 300 hours and 500 hours, and photographs were magnified 50 times. The appearance of black spots was visually observed, and black spot tolerance was evaluated according to the following criteria. Sex.

◎: Black spots are still not produced after 500 hours.

○: After 300 hours of storage, although no black spots appeared, after a 500-hour save, a slight black dot appeared.

△: A slight black spot is generated after 300 hours of storage.

×: After 300 hours of storage, the black spots and unpractical qualities are greatly generated.

Except for Comparative Examples 4 and 8, all the films were observed to emit light, and the organic EL of the aromatic polycarbonate film of the comparative example was used for most of the peeling lines and the substrate on which the protrusions were present, so that the surface flatness was poor, and The illuminance of the illuminating unevenness, the display defect, and the voltage rise are lowered. Moreover, the electric resistance of the conductive layer is uneven, and a black spot is formed by the concentration of the electric charge at one point, which also has a problem of shortening the life.

The aromatic polycarbonate film produced by the production method of the present invention has extremely smooth surface, uneven light emission, display defects, voltage rise, and good black spots, and has been proved to be extremely suitable for an organic EL substrate.

Claims (6)

A method for producing an aromatic polycarbonate film characterized by dissolving 15 to 45 mass% of aromatics in a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 6 carbon atoms a cement composition of polycarbonate, and the ratio of the dichloromethane to the aliphatic alcohol (MA represented by the following formula (i)) is 4 to 14 and the composition of the mortar is inhibited at 0 to 15 ° C at the dew point. In the atmosphere, the flow is molded on an endless belt, and the residual solvent concentration shown in the following formula (ii) is 35 to 45%, and the method is (i) MA = mass of the aliphatic alcohol / (aliphatic) Mass of alcohol + mass of dichloromethane) × 100 Formula (ii) Residual solvent concentration (%) = amount of solvent / (volume amount + dissolved mass) × 100. The method for producing an aromatic polycarbonate film according to claim 1, wherein a ratio of the dichloromethane to the aliphatic alcohol (MA) of 5 to 12 is used. The method for producing an aromatic polycarbonate film according to claim 1 or 2, wherein the dew point of the peeling portion is controlled to be peeled off in an atmosphere of 0 to 5 °C. The method for producing an aromatic polycarbonate film according to claim 1 or 2, wherein the time from the flow molding to the endless belt to the peeling is 120 to 270 seconds. The method for producing an aromatic polycarbonate film according to claim 1 or 2, wherein the aromatic polycarbonate film has a haze of 1.0% or less. The method for producing an aromatic polycarbonate film according to claim 1 or 2, wherein the aromatic polycarbonate film has a surface roughness (Ra) of 0.8 nm or less.