KR20140086810A - Method for manufacturing polyene type polarizer, polyene type polarizer manufactured using the same, polarizing plate comprising the polyene type polarizer and display comprising the polyene type polarizer - Google Patents

Abstract

The purpose of the present invention is to provide a method of manufacturing a new and improved polarizing film, which can stably manufacture a polarizing film having good optical characteristics. To solve the problem, according to one aspect of the present invention, provided is the method of manufacturing a polyene-based polarizing film, which is configured to comprise the steps of using a coating solution containing polyvinyl alcohol and an acid catalyst to manufacture a polyvinyl alcohol film; and performing dehydration reaction of the polyvinyl alcohol film. According to this aspect, the present invention can uniformly disperse the acid catalyst of high concentration within the polyvinyl alcohol film.

Description

TECHNICAL FIELD [0001] The present invention relates to a method of manufacturing a polarizing film, a method of manufacturing the same, a method of manufacturing a polarizing film, a method of manufacturing a polarizing film, a method of manufacturing a polarizing film, a method of manufacturing a polarizing film,

The present invention relates to a method for producing a polyene polarizing film, a polyene polarizing film, a laminated polarizing film and a display device.

BACKGROUND ART [0002] With the spread of OLED display devices using OLEDs (organic light emitting diodes), it is required to increase the transmittance of polarizing films. On the other hand, an iodine polarizing film is known as a polarizing film used in various display devices. Iodine-based polarizing films are widely used.

In the iodine-based polarizing film, a structure contributing to polarization (that is, a structure for absorbing visible light) is iodine. Therefore, in order to increase the transmittance, it is necessary to reduce the amount of iodine in the polarizing film. However, when iodine is sublimated at high temperature and high humidity, the amount of iodine in the polarizing film is reduced, so that iodine in the polarizing film becomes insufficient, and as a result, there is a possibility that the degree of polarization greatly decreases. For this reason, in an iodine polarizing film having a high transmittance (for example, a transmittance of 44% or more), the long-term reliability of the polarizing film at high temperature and high humidity is lowered.

As a polarizing film which is expected to solve such a problem, a dye-based polarizing film and a polyene-based polarizing film disclosed in Patent Document 1 are known. The dye-based polarizing film exhibits excellent heat resistance even when the transmittance is high. However, the dye-based polarizing film has a problem that the degree of polarization tends to decrease when the transmittance is high.

On the other hand, although the polarization degree of the polyene polarizing film is slightly lower than that of the iodine polarizing film, there is an advantage that the reliability at high temperature and high humidity is high even when the transmittance is high. The reason for this is that, in the polyene polarizing film, a constitution contributing to polarization (that is, a constitution for absorbing visible light) becomes polyene (specifically, carbon double bond). Carbon double bonds are hardly affected by temperature or humidity. Therefore, the polyene polarizing film is fundamentally durable against high temperature and high humidity. For this reason, the polyene polarizing film has attracted much attention as a polarizing film for a display device.

As a method of producing a polyene polarizing film, a method of dehydrating polyvinyl alcohol using an acid catalyst is known. Specifically, a polyvinyl alcohol film is impregnated with an aqueous solution of an acid catalyst. Then, the polyvinyl alcohol film is subjected to a heat treatment to cause dehydration reaction to the polyvinyl alcohol. Thereby, a polyene-based polarizing film is produced. As the acid catalyst, hydrochloric acid or sulfuric acid is used.

<Prior Art Literature>

<Patent Literature>

(Patent Document 1) JP2006-99076 A

However, when hydrochloric acid is used as the acid catalyst, the acid catalyst volatilizes as hydrogen chloride together with evaporation of water at the time of heat treatment of the polyvinyl alcohol. For this reason, there is a problem that it is very difficult to control the acid concentration in the polyvinyl alcohol film. If there is a deviation in the acid concentration in the polyvinyl alcohol, deviation or unevenness of optical properties (for example, transmittance, polarization degree) of the polyene polarizing film tends to occur.

As a method for solving this problem, it is considered that the acid concentration in the polyvinyl alcohol film is made constant by controlling the temperature, the humidity and the atmospheric pressure of the environment in which the heat treatment is performed. However, with this method, the manufacturing facility becomes more complicated.

On the other hand, sulfuric acid is a substance hard to volatilize. However, since sulfuric acid is excessively strong in dewatering action, when sulfuric acid is used as an acid catalyst, problems such as intermolecular dehydration and PVA main chain cleavage tend to occur during heat treatment, and the optical characteristics of the polyene- .

Thus, in the conventional method of producing a polyene polarizing film, the production stability and the optical performance were not sufficiently satisfied. On the other hand, Patent Document 1 discloses a technique of using an organic acid as an acid catalyst. However, even with this technique, it has been difficult to keep the acid concentration in polyvinyl alcohol constant.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and an object of the present invention is to provide a novel and improved polarizing film production method and the like capable of stably producing a polarizing film having good optical properties It is on.

According to one aspect of the present invention, there is provided a process for producing a polyvinyl alcohol film, comprising the steps of: preparing a polyvinyl alcohol film by using a coating liquid containing an acid catalyst and polyvinyl alcohol; Wherein the polarizing film is a polarizing film.

According to this aspect, since a high-concentration acid catalyst can be uniformly dispersed in the polyvinyl alcohol film, it is possible to produce a polyene-based polarizing film in which a large number of carbon double bonds are uniformly formed without precisely controlling the environmental temperature and the like have. Therefore, according to this aspect, it becomes possible to stably produce a polyene-based polarizing film having both a high polarization degree and a high transmittance, that is, a polarizing film having good optical characteristics.

Here, the acid catalyst may be a low-volatile acid catalyst.

According to this viewpoint, since the acid catalyst is a low-volatile acid catalyst, it is difficult to evaporate at the time of polyene formation. Therefore, the production method according to this aspect can make the concentration of the acid in the polyvinyl alcohol more uniform even when polyene is produced.

The acid catalyst may have a weight reduction ratio at 100 占 폚 of less than 3 mass%.

According to this viewpoint, the acid catalyst is less likely to evaporate at the time of polyene formation because the weight reduction rate at 100 占 폚 is less than 3 mass%. Therefore, the manufacturing method according to this aspect can make the concentration of the acid in the polyvinyl alcohol more uniform even when polyene is generated.

The acid catalyst may be an organic acid.

According to this viewpoint, since the acid catalyst is an organic acid, it is difficult to evaporate at the time of polyene formation. Therefore, the manufacturing method according to this aspect can make the concentration of the acid in the polyvinyl alcohol more uniform even when polyene is generated.

Further, the organic acid may have any one functional group selected from the group consisting of a carboxylic acid group and a sulfonic acid group.

According to this aspect, since the organic acid has any one functional group selected from the group consisting of a carboxylic acid group and a sulfonic acid group, it is difficult to evaporate at the time of polyene formation. Therefore, the manufacturing method according to this aspect can make the concentration of the acid in the polyvinyl alcohol more uniform even when polyene is generated.

The coating liquid may contain an acid catalyst in an amount of 2% by mass or more and 10% by mass or less with respect to the mass of the polyvinyl alcohol.

According to this aspect, the coating liquid contains an acid catalyst in an amount of 2% by mass or more and 10% by mass or less with respect to the mass of the polyvinyl alcohol. Therefore, the production method according to this aspect can produce a polyene-based polarizing film having a higher polarization degree and a higher transmittance.

The coating liquid may contain an acid catalyst in an amount of 4.0% by mass or more and 10.0% by mass or less with respect to the mass of the polyvinyl alcohol.

According to this aspect, the coating liquid contains an acid catalyst in an amount of 4.0% by mass or more and 10.0% by mass or less with respect to the mass of the polyvinyl alcohol. Therefore, the production method according to this aspect can produce a polyene-based polarizing film having a higher polarization degree and a higher transmittance.

The content of the acid catalyst may be 5% by mass with respect to the mass of the polyvinyl alcohol.

According to this aspect, since the content of the acid catalyst is 5 mass% with respect to the mass of the polyvinyl alcohol, a polyene polarizing film having a higher polarization degree and a high transmittance can be produced.

According to another aspect of the present invention, there is provided a polyene polarizing film produced by the above production method.

The polyene polarizing film according to this aspect is suitable for an organic light emitting display device, for example, because it has both a high polarization degree and a high transmittance.

Here, the thickness of the polyene polarizing film may be less than 10 mu m.

The polyene-based polarizing film according to this aspect has a thickness of less than 10 mu m, so that the shrinkage of the polyene-based polarizing film can be reduced even when the polyene-based polarizing film according to this aspect is applied to a large-screen organic light emitting display. Therefore, according to this aspect, warping of the organic light emitting display device can be reduced.

According to another aspect of the present invention, there is provided a laminated polarizing film characterized by including the polyene polarizing film.

The laminated polarizing film according to this aspect has both a high polarization degree and a high transmittance, and is therefore preferable for an organic light emitting display device, for example.

According to another aspect of the present invention, there is provided a display device comprising the laminated polarizing film.

The display device according to this viewpoint has a laminated polarizing film in which the high polarization degree and the high transmittance are both attained, and therefore, the display device is excellent in various optical characteristics.

INDUSTRIAL APPLICABILITY As described above, according to the present invention, it is possible to uniformly disperse a high-concentration acid catalyst in a polyvinyl alcohol film, and therefore, even when environmental temperature and the like are not precisely controlled, A film can be produced. Therefore, according to the present invention, it is possible to stably produce a polyene-based polarizing film having both a high polarization degree and a high transmittance, that is, a polarizing film having good optical characteristics.

Fig. 1 is an explanatory diagram showing a polarizing film according to an embodiment of the present invention and a conventional polarizing film in comparison with each other.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the specification and drawings, constituent elements having substantially the same functional configuration are denoted by the same reference numerals, and redundant description will be omitted.

(Production method of polarizing film)

First, a method for producing a polarizing film according to the present embodiment will be described. The manufacturing method according to the present embodiment is roughly composed of a step (first step) of producing a polyvinyl alcohol film by using a coating solution containing an acid catalyst and polyvinyl alcohol, and a dehydration reaction in the polyvinyl alcohol film (Second step).

(First step)

In the first step, first, a coating liquid containing an acid catalyst and polyvinyl alcohol is prepared. Specifically, polyvinyl alcohol is added to water, and a mixed liquid of water and polyvinyl alcohol is heated while stirring to dissolve the polyvinyl alcohol sufficiently in water. Then, an acid catalyst and a leveling agent are added to a polyvinyl alcohol aqueous solution and stirred to prepare a coating liquid.

The degree of polymerization of polyvinyl alcohol may be 1500-5000, specifically 1500-2500. In the above range, there is no problem that the film is broken even in the wet stretching of the film.

The saponification degree of polyvinyl alcohol may be 95-100 mol%. For example, 99.9 mol%. Within the above range, there can be obtained an effect of excellent durability and high elongation.

As described above, in this embodiment, the acid catalyst is mixed in advance in the coating liquid. Thereby, the acid concentration in the polyvinyl alcohol can be made more uniform. That is, the acid catalyst can be more uniformly dispersed in the polyvinyl alcohol.

The kind of the acid catalyst is not particularly limited, but it is preferably a low volatile acid catalyst. When the acid catalyst is low in volatility, the evaporation of the acid catalyst during polyene formation is suppressed, so that the acid concentration in the polyvinyl alcohol can be more uniform.

More specifically, it is preferable that the acid catalyst has a weight reduction ratio at 100 占 폚 of less than 3 mass%. When the weight loss rate at 100 占 폚 is less than 3 mass%, for example, 0.1-2.5 mass%, the acid concentration in the polyvinyl alcohol can be made more uniform at the time of polyene formation.

Examples of the acid catalyst that meets the above requirements include organic acids. The organic acid may have any one functional group selected from the group consisting of, for example, a carboxylic acid group and a sulfonic acid group. The specific constitution of the organic acid is represented by R-X. R is not particularly limited as long as it is a compound composed of carbon, hydrogen and fluorine. R is any one selected from, for example, an alkyl group having 1 to 12 carbon atoms, a perfluoroalkyl group having 1 to 12 carbon atoms, an aromatic functional group having 1 to 12 carbon atoms, and a fluorinated aromatic group having 1 to 12 carbon atoms. X is any one functional group selected from the group consisting of a carboxylic acid group and a sulfonic acid group. Specific examples of the organic acid include para-toluenesulfonic acid.

For example, when the paratoluenesulfonic acid is heated at 100 占 폚 for 10 minutes, the weight reduction rate is the detection limit (10 ppm or less) of the analytical instrument. As for the analyzer, ion chromatography and the like can be mentioned. In the analysis method, the sample is heated on a heat plate to collect the generated gas. Subsequently, the gas is bubbled in water and replaced. Quantitative analysis is carried out by ion chromatography.

Further, since the concentration of the saturated aqueous solution of para-toluenesulfonic acid is higher than that of hydrochloric acid, when the para-toluenesulfonic acid is used as the acid catalyst, a higher concentration of the acid catalyst can be dispersed in the polyvinyl alcohol. In addition, the acid catalyst remaining on the polyene polarizing film may lower the durability of the polyene polarizing film, but paratoluene sulfonic acid is more easily removed from the polyene polarizing film than hydrochloric acid.

The content ratio of the acid catalyst is not particularly limited, but is preferably 2% by mass or more and 10% by mass or less with respect to the mass of the polyvinyl alcohol, and more preferably 4.0% by mass or more and 10.0% by mass or less. Thereby, the time required for the reaction can be reduced, and the adverse reaction can be suppressed. Further, the dehydration reaction can be easily controlled, and at the same time, the corrosion of the production apparatus can be suppressed. For example, when the content ratio of the acid catalyst is less than 4% by mass, it takes 10 minutes or more to start the reaction at the dehydration temperature of 140 占 폚, and a long time is required until the reaction is completed do).

The content ratio of the acid catalyst is most preferably 5% by mass. When the content ratio of the acid catalyst becomes this value, a polyene-based polarizing film in which a high transmittance and a high degree of polarization are combined is produced. On the other hand, the degree of polarization of the polyene polarizing film can be controlled by the content ratio of the acid catalyst. As the number of the acid catalyst increases, the amount of polyenes (that is, carbon double bonds) in the polyvinyl alcohol increases, and the degree of polarization increases.

On the other hand, the transmittance tends to increase as the distribution of the contribution to polarization (carbon double bonds in the polyene polarizing film and iodine in the iodine polarizing film) becomes uniform. In the conventional method of producing a polyene polarizing film, the distribution of carbon double bonds in the polyene polarizing film was uneven because the acid concentration in the polyvinyl alcohol could not be made uniform. Therefore, not only the polarization degree is not uniform but also the transmittance is uneven. On the other hand, in the present embodiment, since an acid catalyst is preliminarily mixed into polyvinyl alcohol, a desired concentration of the acid catalyst can be more uniformly dispersed in polyvinyl alcohol. Therefore, in the present embodiment, it is possible to produce a polyene-based polarizing film having both high transmittance and high degree of polarization.

The leveling agent is not particularly limited, but a leveling agent such as a perfluoroalkylethylene oxide adduct is suitable.

Next, a polyvinyl alcohol film is formed on the substrate by coating the coating liquid on a substrate (for example, a lead-free film) and drying. Here, the layer thickness of the polyvinyl alcohol film is not particularly limited, but it is preferable that the film thickness of the finally prepared polyenic polarizing film is adjusted to 10 占 퐉. In an embodiment, the thickness of the polyvinyl alcohol film comprising the acid catalyst may be 0.5-10.0 mu m. In the above range, it can be used for a polarizing plate application, and can prevent breakage in stretching.

(Second step)

In the second step, polyvinyl alcohol in the polyvinyl alcohol film is subjected to a dehydration reaction to form polyene (carbon double bond). Concretely, the polyvinyl alcohol film is heated so that the polyvinyl alcohol is dehydrated. In this embodiment, since the acid catalyst is uniformly distributed in the polyvinyl alcohol, the carbon double bond is uniformly formed in the polyvinyl alcohol. The heating temperature and heating time are not particularly limited and may be suitably set according to the desired degree of polarization.

The polyvinyl alcohol is dehydrated and the polyvinyl alcohol film is stretched in a predetermined direction. Hereinafter, the stretching performed in a liquid is referred to as wet stretching, and the stretching performed in a gas (for example, in the air) is also referred to as dry stretching, thereby aligning the orientations of carbon double bonds. But may be, for example, 1.1 to 6 times, for example, about 4 times. Dry drawing and wet drawing described later may be performed in alignment with the substrate.

Dewatering and dry stretching may include treating the polyvinyl alcohol film at 50-150 占 폚 for 1-20 minutes.

Next, a polyvinyl alcohol film is charged into an aqueous solution of boric acid, and polyvinyl alcohol is stretched in an aqueous solution of boric acid in the same direction as dry stretching. That is, polyvinyl alcohol is wet-drawn. The magnification of the wet stretching is not particularly limited, but is, for example, 1.1 to 3.5 times, for example, 1.5 times. When the dry stretching magnification is 4 times and the wet stretching magnification is 1.5 times, the polyvinyl alcohol film is stretched 6 times in total. Thereafter, the polyvinyl alcohol film is dried to produce a polyene polarizing film. The aqueous solution of boric acid may be an aqueous solution of 0.1 to 5% by weight of boric acid. Within this range, there may be an effect of immobilizing the double bond of the polyene.

The wet stretching may include stretching the polyvinyl alcohol film in an aqueous boric acid solution at 20-60 占 폚 for 1-20 minutes.

As described above, in this embodiment, since the acid catalyst is mixed in the coating liquid, it is possible to uniformly disperse the acid catalyst of high concentration in the polyvinyl alcohol. Therefore, in the present embodiment, it is possible to produce a polyene-based polarizing film in which a plurality of carbon double bonds are uniformly dispersed. That is, in the present embodiment, it is possible to produce a polyene-based polarizing film having both a high polarization degree and a high transmittance. In addition, in the present embodiment, unevenness of the polyene-based polarizing film can be reduced. In addition, since the step of impregnating polyvinyl alcohol into the acid catalyst aqueous solution becomes unnecessary, the production process can be simplified.

Further, in the present embodiment, since the acid catalyst is mixed in the coating liquid, even if the polyvinyl alcohol film is thinned, the high concentration acid catalyst can be uniformly dispersed in the polyvinyl alcohol film. Therefore, in the present embodiment, a polyene polarizing film having a thin film, high polarization degree, and high transmittance can be produced. For example, in the present embodiment, the transmittance is set to 44% or more, for example, 44-46%, while the thickness of the polyene-based polarizing film is set to 10 μm or less, for example, %, For example, 98 to 100%. When an organic acid is used as the acid catalyst, evaporation of the acid catalyst at the time of polyene formation is suppressed, and the degree of polarization can be further improved.

On the other hand, in the conventional production method, since the polyvinyl alcohol film is impregnated with the aqueous acid catalyst solution, when the polyvinyl alcohol film is made thin, the polyvinyl alcohol film can not be impregnated with a sufficient amount of the acid catalyst. Also, since hydrochloric acid is easily volatilized, hydrochloric acid volatilizes when polyene is produced. For this reason, in the conventional production method, since polyene, that is, carbon double bond, could not be sufficiently produced, it was impossible to produce a polyene polarizing film having a high degree of polarization while being a thin film.

The polyene-based polarizing film is peeled from the substrate, and then bonded to a protective film and a retardation film (1/4? Film). Thus, a laminated polarizing film is produced.

An example of the laminated polarizing film is shown in Fig. 1 shows the laminated polarizing film 10 according to the present embodiment and the conventional iodine laminated polarizing film 100 in contrast to each other. 1 (a) shows a conventional iodine-based laminated polarizing film 100, and Fig. 1 (b) shows a laminated polarizing film 10 according to the present embodiment.

The conventional laminated polarizing film 100 is composed of the iodine polarizing film 110, the protective films 120 and 130, the pressure sensitive adhesive layers 140 and 160, and the retardation film (1/4 λ film) 150 Respectively. The conventional iodine-based polarizing film 110 needs to be thickened to realize a desired degree of polarization. For example, the iodine-based polarizing film 110 had a film thickness of 22 mu m or more. For this reason, the film thickness of the entire laminated polarizing film 100 also tends to become thick. For example, the laminated polarizing film 100 has a film thickness of 190 μm or more.

On the other hand, the laminated polarizing film 10 according to the present embodiment is a laminated polarizing film 10 comprising a polyene polarizing film 11, UV adhesive layers 12 and 14, a protective film 13, a retardation film 15, and a pressure-sensitive adhesive layer 16.

Therefore, the laminated polarizing film 10 is a circularly polarizing film. The laminated polarizing film 10 according to the present embodiment may be made of a known material other than the polyene-based polarizing film 11. The pressure-sensitive adhesive layer 16 is bonded to, for example, a display surface of a display device. In the present embodiment, since the polyene laminated polarizing film 11 is made thinner, the entire laminated polarizing film 10 associated therewith becomes thinner. For example, in the present embodiment, the film thickness of the laminated polarizing film 10 as a whole can be made 100 탆 or less. Of course, the laminated polarizing film according to the present embodiment may have another structure. The laminated polarizing film may not be a circular polarizing film. The laminated polarizing film may have a transmittance of 44% or more, for example, 44-46%, and a degree of polarization of 97% or more, for example, 98-100%.

(Example)

(Example 1)

Next, a first embodiment of the present embodiment will be described. In Example 1, a polyene polarizing film and a laminated polarizing film were produced as follows.

(First step)

First, polyvinyl alcohol (JC-25 manufactured by Japan VAM & POVAL Co., Ltd.) was added to water as a solvent. Then, the mixed liquid of water and polyvinyl alcohol was heated with stirring to sufficiently dissolve the polyvinyl alcohol in water. Subsequently, paratoluene sulfonic acid and a leveling agent (Megapak, product of DIC Corporation) were added to an aqueous polyvinyl alcohol solution and stirred to prepare a coating solution. Here, the impregnation ratio (mass ratio) of water, polyvinyl alcohol and paratoluene sulfonic acid in the coating liquid was 89.5 mass%: 10 mass%: 0.5 mass%. The mass ratio of the leveling agent is an external number, specifically 0.002 mass% with respect to the total mass of water, polyvinyl alcohol and para-toluene sulfonic acid.

Next, a lead-free film composed of isophthalic acid copolymerized polyethylene terephthalate (PET) was prepared as a substrate, and the coating liquid was coated on the substrate. Subsequently, the coating solution was dried to produce a polyvinyl alcohol film. The film thickness of the polyvinyl alcohol film was 10 mu m.

(Second step)

The polyvinyl alcohol film was placed in an oven preheated to 140 캜 and heated at 140 캜 for 120 seconds. Thereby, dehydration reaction was performed on the polyvinyl alcohol in the polyvinyl alcohol film to form polyene (carbon double bond). On the other hand, the polyvinyl alcohol was dehydrated, and the polyvinyl alcohol film and the substrate were aligned and dry-drawn 4 times in a predetermined direction.

Then, a polyvinyl alcohol film was charged into a 5 mass% boric acid aqueous solution (an aqueous boric acid solution containing boric acid having 5 mass% based on the total mass of the aqueous boric acid solution) adjusted to 85 캜, and the polyvinyl alcohol film and the substrate were immersed in an aqueous boric acid solution In the same direction as that of dry drawing. As a result, the polyvinyl alcohol film was stretched 6 times in total. Thereafter, the polyvinyl alcohol film was placed in an oven preheated to 80 DEG C and dried at 80 DEG C for 2 minutes. Thus, a polyene-based polarizing film according to Example 1 was produced. The film thickness of the polyene polarizing film was 5 占 퐉.

Subsequently, a UV adhesive of the following composition was prepared.

(a) 90 mass%, (b) 10 mass%, (c) 1 mass% and (d) 2 mass% were mixed using a stirrer. The content ratio of (c) and (d) is the outside number with respect to the mass of (a) + (b).

(a) 4HBA (4-hydroxybutyl acrylate)

(b) Celloxide 2021P (3, 4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate) (Daicel Corporation)

(c) TPO (2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide) (available from Ciba Specialty Chemicals Holding Inc.)

(d) CPI-110P (p-phenylthiophenyldiphenylsulfonium PF6 salt) (SAN-APRO LTD.))

Then, a UV adhesive was applied to the surface of the polyene polarizing film (the side on which the polyene polarizing film was exposed in the front and back surfaces of the laminated film composed of the polyene polarizing film and the substrate) with a thickness of 2 m. Then, a protective film (ultraviolet absorber-containing triacetylcellulose film: FUJIFILM Corporation, "Fujitac") having a thickness of 50 mu m was laminated on the surface of the polyene polarizing film so as to fit the UV adhesive. Thereby, the laminated film comprising the polyene polarizing film and the substrate was stuck to the protective film. Next, 1000 mJ of UV light was irradiated to the laminated film to cure the UV adhesive. Subsequently, the substrate was peeled off from the polyene polarizing film.

Next, a UV adhesive was applied to the back surface of the polyene polarizing film (the surface exposed by the peeling) to a thickness of 2 m. Next, a retardation film (1/4 wave plate, product of Teijin Chemicals Ltd., &quot; WRS &quot;) having a film thickness of 50 占 퐉 was laminated on the back surface of the polyene polarizing film with an optical absorption axis of the poly 4 wave plate so that the ground axis is 45 degrees. Then, the UV adhesive was cured by the above process. Thus, a laminated polarizing film for evaluation was produced.

(Comparative Example)

Next, a polyene polarizing film and a laminated polarizing film according to comparative examples were produced by the following process.

First, polyvinyl alcohol (JC-25 produced by Nihon Sakubi Co., Ltd.) was added to water as a solvent. Then, the mixed liquid of water and polyvinyl alcohol was heated with stirring to sufficiently dissolve the polyvinyl alcohol in water. Then, a leveling agent (Megapak Co., Ltd.) was added to the polyvinyl alcohol aqueous solution and stirred to prepare a coating solution. Here, the impregnation ratio (mass ratio) of water, polyvinyl alcohol and leveling agent in the coating liquid was 90 mass%: 10 mass%: 0.002 mass%. That is, the mass ratio of the leveling agent was set to 0.002 mass% as the external water.

Next, a lead-free film composed of isophthalic acid copolymerized polyethylene terephthalate (PET) was prepared as a substrate, and the coating liquid was coated on the substrate. Next, the coating solution was dried to prepare a polyvinyl alcohol film. The film thickness of the polyvinyl alcohol film was 10 mu m.

Then, a polyvinyl alcohol film was fed into a 0.5 mass% hydrochloric acid aqueous solution (hydrochloric acid aqueous solution containing 0.5 mass% hydrochloric acid based on the total mass of the hydrochloric acid aqueous solution) adjusted to 10 ° C, 3-fold wet stretching. That is, in the comparative example, a polyvinyl alcohol film was impregnated with a hydrochloric acid aqueous solution, and wet stretching was performed in this state.

Then, the polyvinyl alcohol film was taken out from the hydrochloric acid aqueous solution and placed in an oven preheated at 65 占 폚. Then, the polyvinyl alcohol film was dried at 65 캜 for 15 minutes. Next, the polyvinyl alcohol film was put into an oven preheated to 130 캜 and dry-stretched twice in the same direction as the wet stretching. That is, the polyvinyl alcohol film was stretched 6 times. Then, the polyvinyl alcohol film was heated at 130 DEG C for 30 minutes to conduct dehydration reaction in the polyvinyl alcohol film. Thus, a polyene-based polarizing film was produced. Subsequently, a laminated polarizing film was produced in the same manner as in Example 1.

(evaluation)

The polarizing degree and transmittance (single transmittance) of the laminated polarizing film according to Example 1 and Comparative Example were evaluated by the following treatments.

Measurement apparatus: spectrophotometer (V7100 manufactured by JASCO Corporation)

Measurement method: The simple transmittance (T), the parallel transmittance (Tp) and the quadrature transmittance (Tc) of the polarizing element were measured. These are the Y values measured by the 2-degree field of view (C light source) of JIS Z8701 and subjected to visibility correction. The degree of polarization (P) was determined by the following formula (1) using the above transmittance.

[Equation 1]

(%) = {(Tp-Tc) / (Tp + Tc)} ^1/2 100

The measurement results are shown in Table 1.

T P Example 1 44.90% 97.085% Comparative Example 44.03% 96.506%

According to this evaluation, it can be seen that the laminated polarizing film according to Example 1 achieves both high polarization degree and high transmittance. On the other hand, the laminated polarizing film according to the comparative example has low polarization degree and low transmittance. In Example 1, since the organic acid as the acid catalyst is mixed into the coating liquid, the high concentration of the acid catalyst is uniformly dispersed in the polyvinyl alcohol. Further, since the organic acid is low in volatility, it is difficult to evaporate when polyene is produced. Therefore, in Example 1, since a large number of carbon double bonds are uniformly formed, the degree of polarization and transmittance are high. On the other hand, in the comparative example, since the polyvinyl alcohol film is impregnated with an aqueous hydrochloric acid solution, the distribution of hydrochloric acid in the polyvinyl alcohol is uneven. In addition, hydrochloric acid is volatile, so it evaporates when polyene is produced. Therefore, the number of carbon double bonds is smaller than that of Example 1, and the distribution is also uneven.

(Examples 2 to 4)

Next, Examples 2 to 4 were carried out in order to confirm a preferable content ratio of para-toluenesulfonic acid (content ratio to polyvinyl alcohol). In Examples 2 to 4, the same treatment as in the process up to dry drawing of Example 1 except that the content ratio of paratoluene sulfonic acid and the dehydration time (heating time) during dry drawing were changed as shown in Table 2 below . Thus, dry stretched films according to Examples 2 to 4 were produced. These dry stretched films are composed of a polyvinyl alcohol film and a substrate.

The transmittance (single transmittance) of the dry stretched films according to Examples 2 to 4 was measured in the same manner as in Example 1. [ The measurement results are shown in Table 2. The transmittance of the dry drawn film of Example 1 is also shown in Table 2.

content Dehydration time Transmittance Example 1 5 mass% 2 minutes 40.3% Example 2 10 mass% 1 minute 27% Example 3 4 mass% 10 minutes 39% Example 4 2 mass% 45 minutes 40%

Although the transmittances of Examples 1, 3 and 4 are less than 44%, the transmittance can be made 44% or more by performing wet drawing in the same manner as in Example 1 on the dry stretched film. In Example 2, although the transmittance is lower than that in Examples 1, 3 and 4, the transmittance can be set to about 40% by making the dehydration time shorter than 1 minute. That is, when the content ratio of the acid catalyst was large, the dehydration reaction progressed quickly, and the reaction proceeded excessively even with the above dehydration time (1 minute). Therefore, in Example 2, the transmittance can be set to about 40% by shortening the dehydration time. In Example 4, although the transmittance was high, the dehydration time was extremely long. In the case of producing a roll roll film, the longer the dewatering time, the longer the drying furnace is. Thus, from the viewpoints of the control of the transmittance and the dehydration time, the content ratio of the acid catalyst is preferably 4% by mass or more and 10% by mass or less.

As described above, the method for producing a polyene polarizing film according to the present embodiment includes the steps of: preparing a polyvinyl alcohol film by using a coating solution containing an acid catalyst and polyvinyl alcohol; and performing a dehydration reaction on the polyvinyl alcohol film .

Therefore, it is possible to uniformly disperse the high-concentration acid catalyst in the polyvinyl alcohol film, so that it is possible to produce a polyene-based polarizing film in which a large number of carbon double bonds are uniformly formed without controlling the environmental temperature precisely as in the prior art. Therefore, according to the manufacturing method according to the present embodiment, it is possible to stably produce a polyene-based polarizing film having both a high polarization degree and a high transmittance, that is, a polarizing film having good optical characteristics.

Such a polyene polarizing film having a high polarization degree and a high transmittance is suitable for an antireflection laminated polarizing film of an organic light emitting display device expected to be widely used in the future. In addition, since the polyene-based polarizing film essentially has high durability against high temperature and high humidity, the polyene-based polarizing film according to the present embodiment not only has good optical properties, but also has high durability against high temperature and high humidity. In a display device having such a polyene polarizing film, various optical characteristics are improved.

Since the acid catalyst is a low-volatile acid catalyst, it is difficult to evaporate at the time of polyene formation. Therefore, the production method according to the present embodiment can make the concentration of the acid in the polyvinyl alcohol even more uniform even when polyen is produced.

Further, since the acid catalyst has a weight reduction ratio of less than 3 mass% at 100 占 폚, it is difficult to evaporate at the time of polyene formation. Therefore, the production method according to the present embodiment makes it possible to make the concentration of the acid in the polyvinyl alcohol more uniform even when polyen is produced.

Further, since the acid catalyst is an organic acid, it is difficult to evaporate when polyene is produced. Therefore, the production method according to the present embodiment can make the concentration of the acid in the polyvinyl alcohol even more uniform even when polyen is produced.

Further, since the organic acid has any one functional group selected from the group consisting of a carboxylic acid group and a sulfonic acid group, it is difficult to evaporate at the time of polyene formation. Therefore, the production method according to the present embodiment can make the concentration of the acid in the polyvinyl alcohol even more uniform even when polyen is produced.

In the production method according to the present embodiment, the coating liquid contains an acid catalyst in an amount of 2 mass% or more and 10 mass% or less, and more preferably 4.0 mass% or more and 10.0 mass% or less, with respect to the mass of polyvinyl alcohol . Therefore, the production method according to the present embodiment can produce a polyene-based polarizing film having a higher polarization degree and a high transmittance.

Further, since the content of the acid catalyst is 5 mass% with respect to the mass of the polyvinyl alcohol, the production method according to the present embodiment can produce a polyene polarizing film having a higher polarization degree and a high transmittance.

Further, in the manufacturing method according to the present embodiment, the polyene polarizing film can be made thin. Specifically, in the manufacturing method according to the present embodiment, the film thickness of the polyene-based polarizing film can be made less than 10 mu m. Thus, even when the polyene-based polarizing film is applied to a large-screen organic light-emitting display device, shrinkage of the polyene-based polarizing film can be reduced, and further, warpage of the organic light-emitting display device can be reduced.

While the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to these examples. It will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Of the present invention.

10: laminated polarizing film, 11: polyene-based polarizing film
12, 14: UV adhesive layer, 13: protective film
15: retardation film, 16: pressure-sensitive adhesive layer

Claims (16)

Preparing a polyvinyl alcohol film by using a coating solution containing an acid catalyst and polyvinyl alcohol;
And a step of allowing the polyvinyl alcohol film to undergo a dehydration reaction. The method for producing a polyene polarizing film according to claim 1, wherein the acid catalyst is a low-volatile acid catalyst. The method for producing a polyene polarizing film according to claim 2, wherein the acid catalyst has a weight reduction ratio at 100 ° C of less than 3 mass%. The method for producing a polyene polarizing film according to claim 2, wherein the acid catalyst is an organic acid. The method for producing a polyene polarizing film according to claim 4, wherein the organic acid has at least one functional group selected from the group consisting of a carboxylic acid group and a sulfonic acid group. The method for producing a polyene polarizing film according to claim 1, wherein the coating solution contains 2% by mass or more and 10% by mass or less of the acid catalyst relative to the mass of the polyvinyl alcohol. The method for producing a polyene polarizing film according to claim 6, wherein the coating solution contains 4.0% by mass or more and 10.0% by mass or less of the acid catalyst with respect to the mass of the polyvinyl alcohol. The method for producing a polyene polarizing film according to claim 7, wherein the content of the acid catalyst is 5% by mass with respect to the mass of the polyvinyl alcohol. The method for producing a polyene polarizing film according to claim 1, wherein the polyvinyl alcohol has a polymerization degree of 1500-5000. The method for producing a polyene polarizing film according to claim 1, wherein the production method further comprises a step of wet-stretching the polyvinyl alcohol film after the dehydration reaction. The method for producing a polyene polarizing film according to claim 10, wherein the wet stretching comprises stretching the polyvinyl alcohol film in an aqueous solution of boric acid at 20-60 占 폚. A polyene-based polarizing film produced by the production method according to any one of claims 1 to 11. The polyene-based polarizing film according to claim 12, wherein the polyene-based polarizing film has a thickness of less than 10 mu m. A laminated polarizing film comprising the polyene-based polarizing film according to claim 12. 15. The laminated polarizing film according to claim 14, wherein the laminated polarizing film has a transmittance of 44% or more and a degree of polarization of 97% or more. A display device comprising the laminated polarizing film according to claim 14.

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