KR20220049491A - Polarizing film, laminated polarizing film, image display panel, and image display device - Google Patents

Abstract

A polarizing film in which a transparent protective film is bonded to both sides of a polarizing film, wherein the polarizing film is formed by adsorption orientation of iodine on a polyvinyl alcohol-based film, and an iodine concentration of 3 wt% or more and 10 wt% or less, the transparent protective film At least one has a moisture permeability of 200 g/(m 2 ·24h) or less, and the polarizing film has a change amount (ΔTs) of a single transmittance represented by the general formula (1): ΔTs(%)=Ts ₇₅₀ -Ts ₀ 0% or more 5% or less is satisfied. The polarizing film has a good initial polarization degree, is excellent in the inhibitory effect of reducing the single transmittance due to coloring of the polarizing film in a high-temperature environment, and is excellent in the inhibitory effect of the decrease in the polarization degree (humidification durability) in a high-temperature, high-humidity environment .

Description

Polarizing film, laminated polarizing film, image display panel, and image display device

The present invention relates to a polarizing film, a laminated polarizing film, an image display panel, and an image display device.

Conventionally, as a polarizing film used for various image display devices such as liquid crystal display devices and organic EL display devices, since it has high transmittance and high polarization degree, it is dyed (contains dichroic substances such as iodine and dichroic dyes) ) A polyvinyl alcohol-based film is used. The said polarizing film is manufactured by performing each process, such as swelling, dyeing|staining, bridge|crosslinking, extending|stretching, in a bath in a bath, for example, performing a washing process, and then drying the said polarizing film. In addition, the said polarizing film is normally used as a polarizing film (polarizing plate) in which the protective film, such as triacetyl cellulose, was bonded together on the single side|surface or both surfaces using the adhesive agent.

The polarizing film is used as a laminated polarizing film (optical laminate) by laminating other optical layers as needed, and the polarizing film or the laminated polarizing film (optical laminate) is an image display cell such as a liquid crystal cell or an organic EL device; It is bonded through an adhesive layer or an adhesive bond layer between front transparent members, such as a front transparent plate (window layer) and a touch panel, in the visual recognition side, and is used as said various image display apparatuses (patent document 1).

In recent years, in addition to mobile devices such as cellular phones and tablet terminals, such various image display devices are being used as vehicle-mounted image display devices such as car navigation devices and back monitors, and their uses are expanding. Accordingly, the image display device is required to have higher durability under harsher environments (eg, under high-temperature environments) than conventionally required, and images for the purpose of ensuring such durability A display device has been proposed (Patent Document 2).

Japanese Patent Laid-Open No. 2014-102353 Japanese Patent Laid-Open No. 2018-101117

Polarizing film or laminated polarizing film using an iodine-based polarizing film has a problem that, when exposed to a high-temperature environment, polyvinyl alcohol constituting the polarizing film is polyenized by a dehydration reaction, resulting in coloration of the polarizing film, and the single transmittance thereof decreases. .

As a result of the present inventors earnestly examining, it discovered that the iodine contained in an iodine type polarizing film accelerated|stimulated polyenization in a high temperature environment. Therefore, it is effective to reduce the iodine concentration (content) in the polarizing film in order to suppress a decrease in the single transmittance due to coloring of the polarizing film in a high-temperature environment. There existed a tendency for peeling at the time of the heating of a polarizing film or a laminated polarizing film to occur easily.

Moreover, in a polarizing film and a laminated polarizing film, the boric acid bridge|crosslinking in a polarizing film isolate|separates in a high-temperature, high-humidity environment, and there existed a problem that the polarization degree fell because an iodine complex was destroyed.

In view of the above circumstances, the present invention has a good initial polarization degree, excellent suppression effect of a decrease in single transmittance due to coloring of a polarizing film under a high-temperature environment, and a suppression effect of a decrease in the degree of polarization under a high-temperature, high-humidity environment It aims at providing the polarizing film which has a polarizing film excellent in (humidification durability).

Moreover, an object of this invention is to provide the laminated polarizing film which used the said polarizing film, an image display panel, and an image display apparatus.

That is, the present invention is a polarizing film in which a transparent protective film is bonded to both surfaces of a polarizing film, wherein the polarizing film is formed by adsorbing and oriented iodine on a polyvinyl alcohol-based film, and an iodine concentration of 3 wt% or more and 10 wt% or less, , at least one of the transparent protective film has a water vapor transmission rate of 200 g/(m 2 ·24h) or less, and the polarizing film has the general formula (1): ΔTs (%) = Ts ₇₅₀ -Ts ₀ (in the general formula (1), Ts ₀ is the single transmittance of the laminate in which a glass plate is bonded to one side of the polarizing film through an adhesive layer, and Ts ₇₅₀ is the single transmittance of the laminate after heat treatment at 105° C. and 750 hours). It relates to a polarizing film satisfying the condition that the amount of change (ΔTs) of is 0% or more and 5% or less.

Moreover, this invention relates to the laminated polarizing film by which the said polarizing film is bonded by the optical layer.

Moreover, this invention relates to the image display panel by which the said polarizing film or the said laminated|multilayer polarizing film is bonded by the image display cell.

Moreover, this invention relates to the image display apparatus provided with the front transparent member on the polarizing film or laminated polarizing film side of the said image display panel.

Although the detail of the action mechanism of the effect in the polarizing film of this invention has an unclear part, it is estimated as follows. However, the present invention does not need to be interpreted as being limited to this mechanism of action.

The polarizing film of the present invention is a polarizing film in which a transparent protective film is bonded to both sides of a polarizing film, wherein the polarizing film is formed by adsorbing and orienting iodine to a polyvinyl alcohol-based film, and has an iodine concentration of 3% by weight or more and 10% by weight or less and at least one of the transparent protective films has a water vapor transmission rate of 200 g/(m 2 ·24h) or less, and the polarizing film has the general formula (1): ΔTs (%) = Ts ₇₅₀ -Ts ₀ (in the general formula (1) , Ts ₀ is the single transmittance of the laminate in which a glass plate is bonded to one side of the polarizing film through an adhesive layer, and Ts ₇₅₀ is the single transmittance after the laminate is heat-treated at 105° C. for 750 hours). It is a polarizing film satisfying the condition that the amount of change in transmittance (ΔTs) is 0% or more and 5% or less. Since the polarizing film of the present invention has a small change amount (ΔTs) of the single transmittance after the heat treatment (under a high temperature environment), it is possible to suppress a decrease in the single transmittance due to coloring of the polarizing film. In this way, it is presumed that the reason why the amount of change (ΔTs) of the single transmittance before and after the heat treatment is small is that the temperature at which the dehydration reaction due to polyenization occurs in the polarizing film of the present invention is higher than that of the conventional polarizing film. In particular, the heat treatment is a heat durability test that is an index of the heat resistance of an in-vehicle display, and is more severe than the conventional heat durability test. Further, in the polarizing film of the present invention, by setting the iodine concentration in the polarizing film to a certain range, the temperature at which the dehydration reaction by polyenization occurs can be controlled to the high temperature side, and the initial degree of polarization becomes good.

In addition, in the polarizing film of the present invention, since at least one of the transparent protective films has a water vapor transmission rate of 200 g/(m 2 ·24 h) or less, it prevents the ingress of water into the polarizing film, thereby reducing the decrease in the degree of polarization even in a high-temperature, high-humidity environment ( Humidification durability) is excellent.

<Polarizing film>

The polarizing film of the present invention is an iodine-based polarizing film formed by adsorbing and aligning iodine to a polyvinyl alcohol-based film, and has an iodine concentration of 3% by weight or more and 10% by weight or less. The polyvinyl alcohol (PVA)-based film has light transmittance in a visible light region and disperses and adsorbs iodine can be used without particular limitation. Moreover, it is preferable that thickness is about 1-100 micrometers, and, as for the PVA type film normally used as a raw material, it is more preferable that it is about 1-50 micrometers, It is preferable that it is about 100-5000 mm in width.

Examples of the material of the polyvinyl alcohol-based film include polyvinyl alcohol or a derivative thereof. As a derivative of the said polyvinyl alcohol, For example, polyvinyl formal, polyvinyl acetal; olefins such as ethylene and propylene; Unsaturated carboxylic acids, such as acrylic acid, methacrylic acid, and a crotonic acid, and what modified|denatured with its alkylester, acrylamide, etc. are illustrated. The polyvinyl alcohol preferably has an average degree of polymerization of about 100 to 10,000, more preferably about 1,000 to 10,000, and still more preferably about 1,500 to 4,500. Further, the polyvinyl alcohol preferably has a degree of saponification of about 80 to 100 mol%, more preferably about 95 mol% to 99.95 mol. In addition, the said average degree of polymerization and the said saponification degree can be calculated|required according to JISK6726.

The said polyvinyl alcohol-type film may contain additives, such as a plasticizer and surfactant. As said plasticizer, polyols, such as glycerol, diglycerol, triglycerol, ethylene glycol, propylene glycol, polyethyleneglycol, its condensate, etc. are illustrated, for example. Although there is no restriction|limiting in particular in the usage-amount of the said additive, For example, about 20 weight% or less in a polyvinyl alcohol-type film is suitable.

In the polarizing film, the iodine concentration (content) is 3% by weight or more and 10% by weight or less from the viewpoint of improving the initial polarization degree of the polarizing film and increasing the temperature at which the dehydration reaction by polyenization occurs. In the polarizing film, the iodine concentration (content) is preferably 3.5% by weight or more, more preferably 4% by weight or more, from the viewpoint of improving the initial polarization degree of the polarizing film, and the temperature at which the dehydration reaction by polyenization occurs is set to a high temperature. It is preferably 9 wt% or less from the viewpoint of

It is preferable that the said polarizing film contains the compound which has a radical trapping function. It is estimated that the compound having the radical trapping function captures radicals generated by heating of the polyvinyl alcohol of the polarizing film, and can set the temperature at which the dehydration reaction of polyenization occurs to the high temperature side. Examples of the compound having the radical trapping function include radicals such as hindered phenol-based, hindered amine-based, phosphorus-based, sulfur-based, benzotriazole-based, benzophenone-based, hydroxylamine-based, salicylic acid ester-based, and triazine-based compounds. A compound having a trapping function is exemplified. The compound having a radical trapping function is preferably a compound having, for example, a nitroxy radical or a nitroxide group from the viewpoint that the temperature at which the dehydration reaction of polyenization occurs can be easily set to the high temperature side. The compound which has the said radical trapping function may be used independently and may use 2 or more types together.

As the compound having a nitroxy radical or a nitroxide group, an N-oxyl compound (as a functional group, a compound having C-N(-C)-O· (O· is an oxy radical )) are exemplified, and a known one can be used. As a compound which has the said nitroxy radical or a nitroxide group, the compound etc. which have an organic group of the following structures are illustrated, for example.

(In the general formula (1), R ¹ represents an oxy radical, R ² to R ⁵ independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and n represents 0 or 1) The left side of the dotted line part in Formula (1) shows arbitrary organic groups.

As a compound which has the said organic group, the compound etc. which are represented by the following general formula (2) - (5) are illustrated, for example.

(In general formula (2), R ¹ to R ⁵ and n are the same as above, R ⁶ represents a hydrogen atom or an alkyl group, acyl group, or aryl group having 1 to 10 carbon atoms, and n is 0 or represents 1)

(In general formula (3), R ¹ to R ⁵ and n are the same as above, and R ⁷ and R ⁸ independently represent a hydrogen atom or an alkyl group, acyl group, or aryl group having 1 to 10 carbon atoms. )

(In general formula (4), R ¹ to R ⁵ and n are the same as above, and R ⁹ to R ¹¹ are independently a hydrogen atom, or an alkyl group, acyl group, amino group, or alkoxy group having 1 to 10 carbon atoms. , a hydroxy group, or an aryl group)

(In general formula (5), R ¹ to R ⁵ and n are the same as above, and R ¹² represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, an amino group, an alkoxy group, a hydroxyl group, or an aryl group)

In the general formulas (1) to (5), R ² to R ⁵ are preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, from the viewpoint of availability. Moreover, in the said General formula (2), from a viewpoint of availability, it is preferable that R< ⁶ > is a hydrogen atom or a C1-C10 alkyl group, and it is more preferable that it is a hydrogen atom. In the general formula (3), R ⁷ and R ⁸ independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, more preferably a hydrogen atom from the viewpoint of availability. Further, in the general formula (4), from the viewpoint of availability, R ⁹ to R ¹¹ are preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. Moreover, in the said General formula (5), it is preferable from a viewpoint of availability that R< ¹² > is a hydroxyl group, an amino group, or an alkoxy group. In the general formulas (1) to (5), n is preferably 1 from the viewpoint of availability.

Moreover, as a compound which has the said nitroxy radical or a nitroxide group, the following compounds etc. are illustrated, for example.

(In general formula (6), R represents a hydrogen atom or an alkyl group, acyl group, or aryl group having 1 to 10 carbon atoms)

Further, the compound having a radical trapping function has a molecular weight of preferably 1000 or less, more preferably 500 or less, and still more preferably 300 or less from the viewpoint of efficiently trapping radicals generated in the polyenization reaction.

In addition, the compound having the radical trapping function is preferably a water-soluble compound that can dissolve 1 part by weight or more with respect to 100 parts by weight of water at 25°C from the viewpoint of easy transfer to moisture in the polarizing film, and 100 parts by weight of water at 25°C It is more preferable that it is a water-soluble compound which can dissolve 2 weight part or more with respect to part, and it is still more preferable that it is a water-soluble compound which can dissolve 5 weight part or more with respect to 100 weight part of 25 degreeC water.

When the polarizing film contains the compound having the radical trapping function, the content of the compound having the radical trapping function is 0.01 in the polarizing film from the viewpoint of suppressing a decrease in the single transmittance due to coloring of the polarizing film in a high temperature environment. It is preferable that it is weight % or more, It is more preferable that it is 0.02 weight% or more, It is still more preferable that it is 0.05 weight% or more, And from the viewpoint of an external appearance, it is preferable that it is 10 weight% or less, It is more preferable that it is 7 weight% or less, It is 3 weight% It is more preferable that it is the following.

The polarizing film preferably contains chlorine ions (chloride ions). It is estimated that the chlorine ion is deliquescent and delays the dehydration reaction caused by heating the polyvinyl alcohol of the polarizing film, so that the temperature at which the dehydration reaction of polyenization occurs can be set to the high temperature side.

When the polarizing film contains chlorine ions (chloride ions), the content of the chlorine ions is more than 2% by weight in the polarizing film from the viewpoint of suppressing a decrease in the single transmittance due to coloring of the polarizing film in a high-temperature environment. Preferably, it is more preferably 2.5% by weight or more, more preferably 3% by weight or more, and from the viewpoint of color change of the polarizing film in a high-temperature environment, it is preferably 10% by weight or less, and more preferably 7% by weight or less, , more preferably 5% by weight or less.

<Method for producing a polarizing film>

The method for producing the polarizing film is obtained by subjecting the polyvinyl alcohol-based film to an optional swelling step and washing step, at least a dyeing step, a crosslinking step, and an stretching step. The content of the iodine contained in the polarizing film is the concentration of iodide such as iodine and potassium iodide contained in any one of the treatment baths in the swelling step, the dyeing step, the crosslinking step, the stretching step and the washing step, It is controllable by the processing temperature and processing time by each said processing bath.

In addition, when manufacturing a polarizing film containing a compound having the radical trapping function, the radical trapping function is provided in the treatment bath of any one or more of the swelling step, the washing step, the dyeing step, the crosslinking step, and the stretching step. What is necessary is just to contain the compound which has. The concentration of the compound having the radical trapping function contained in any one of the respective treatment baths cannot be determined collectively because it is affected by the number of treatments, treatment time, treatment temperature, etc. of each treatment, but the radical trapping function in the polarizing film From the viewpoint of being able to efficiently control the content of the compound having It is more preferable that it is 10 weight% or less, and it is still more preferable that it is 5 weight% or less.

In particular, when the washing process is performed after the dyeing process, the crosslinking process, and the extending process are performed, the washing process is performed after considering the treatment conditions in the dyeing process, the crosslinking process, and the stretching process, and then iodine or a compound having the above radical trapping function It is easy to adjust content of the said iodine and the compound which has the said radical trapping function to a desired range from a viewpoint of being able to elute from a polyvinyl alcohol-type film, or make it adsorb|suck to a polyvinyl alcohol-type film.

Moreover, when manufacturing the polarizing film containing the compound which has the said radical trapping function, you may apply|coat and impregnate the polarizing film with the aqueous solution containing the compound which has the said radical trapping function. The application step may be provided before or after any of the above swelling step, dyeing step, crosslinking step, stretching step, and washing step, and in particular, a cleaning step from the viewpoint of easy adjustment of the content of the compound having a radical trapping function to a desired range. It is preferable to install it later. There is no restriction|limiting in particular as a coating method, For example, the wire bar coating method, the gravure coating method, the spray method etc. are illustrated.

Further, each treatment bath in the swelling step, the dyeing step, the crosslinking step, the stretching step and the washing step may contain additives such as zinc salt, a pH adjuster, a pH buffer, and other salts. Examples of the zinc salt include zinc halides such as zinc chloride and zinc iodide; Inorganic zinc salts, such as zinc sulfate and zinc nitrate, etc. are illustrated. As said pH adjuster, strong acids, such as hydrochloric acid, sulfuric acid, nitric acid, and strong bases, such as sodium hydroxide and potassium hydroxide, are illustrated, for example. Examples of the pH buffer include carboxylic acids and salts thereof such as acetic acid, oxalic acid and citric acid, and weak inorganic acids and salts thereof such as phosphoric acid and carbonic acid. Examples of the other salts include chlorides such as sodium chloride, potassium chloride and barium chloride, nitrates such as sodium nitrate and potassium nitrate, sulfates such as sodium sulfate and potassium sulfate, and salts of alkali metals and alkaline earth metals. In particular, from the viewpoint of obtaining a polarizing film capable of suppressing a decrease in the single transmittance due to coloring of the polarizing film in a high-temperature environment, it is preferable that one or more treatment baths of each of the above treatment baths contain a chloride.

The swelling step is a treatment step of immersing the polyvinyl alcohol-based film in a swelling bath, and it is possible to remove contamination and blocking agents, etc. on the surface of the polyvinyl alcohol-based film, and to reduce dyeing unevenness by swelling the polyvinyl alcohol-based film can be suppressed As the swelling bath, a medium mainly containing water such as water, distilled water, or pure water is used. The said swelling bath follows a conventional method, and surfactant, alcohol, etc. may be added suitably.

It is preferable that the temperature of the said swelling bath is about 10-60 degreeC, It is more preferable that it is about 15-45 degreeC, It is more preferable that it is about 18-30 degreeC. In addition, the immersion time in the swelling bath cannot be determined collectively because the degree of swelling of the polyvinyl alcohol-based film is affected by the temperature of the swelling bath, but it is preferably about 5 to 300 seconds, and 10 to 200 seconds. It is more preferable that it is about, and it is still more preferable that it is about 20 to 100 second. The said swelling process may be implemented only once, and may be implemented multiple times as needed.

The dyeing step is a treatment step in which the polyvinyl alcohol-based film is immersed in a dyeing bath (iodine solution), and iodine can be adsorbed and oriented to the polyvinyl alcohol-based film. It is preferable that the said iodine solution is usually an aqueous iodine solution, and it contains iodine and iodide as a dissolution aid. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, titanium iodide, and the like. Among these, potassium iodide is suitable from a viewpoint of controlling content of potassium in the said polarizing film.

In the said dyeing bath, it is preferable that it is about 0.01 to 1 weight%, and, as for the density|concentration of an iodine, it is more preferable that it is about 0.02 to 0.5 weight%. In the said dyeing bath, it is preferable that the density|concentration of the said iodide is about 0.01 to 20 weight%, It is more preferable that it is about 0.05 to 10 weight%, It is more preferable that it is about 0.1 to 5 weight%.

It is preferable that the temperature of the said dyeing bath is about 10-50 degreeC, It is more preferable that it is about 15-45 degreeC, It is more preferable that it is about 18-30 degreeC. In addition, the immersion time in the dyeing bath cannot be determined collectively because the degree of dyeing of the polyvinyl alcohol-based film is affected by the temperature of the dyeing bath, but it is preferably about 10 to 300 seconds, and 20 to 240 seconds. It is more preferable that it is about. The said dyeing process may be performed only once, and may be performed multiple times as needed.

The crosslinking step is a treatment step in which the polyvinyl alcohol-based film is immersed in a treatment bath (crosslinking bath) containing a boron compound, the polyvinyl alcohol-based film is crosslinked by the boron compound, and iodine molecules or dye molecules are crosslinked adsorbed to the structure. As said boron compound, boric acid, a borate, borax etc. are illustrated, for example. The crosslinking bath is generally an aqueous solution, but may be, for example, a mixed solution of an organic solvent miscible with water and water. Moreover, the said crosslinking bath may contain potassium iodide from a viewpoint of controlling content of potassium in the said polarizing film.

It is preferable that the density|concentration of the said boron compound in the said crosslinking bath is about 1 to 15 weight%, It is more preferable that it is about 1.5 to 10 weight%, It is more preferable that it is about 2 to 5 weight%. Further, when potassium iodide is used in the crosslinking bath, the concentration of potassium iodide in the crosslinking bath is preferably about 1 to 15% by weight, more preferably about 1.5 to 10% by weight, and 2 to 5% by weight. % is more preferable.

It is preferable that it is about 20-70 degreeC, and, as for the temperature of the said crosslinking bath, it is more preferable that it is about 30-60 degreeC. In addition, the immersion time in the crosslinking bath cannot be determined collectively because the degree of crosslinking of the polyvinyl alcohol-based film is affected by the temperature of the crosslinking bath, but it is preferably about 5 to 300 seconds, and 10 to 200 seconds. It is more preferable that it is about. The said crosslinking process may be performed only once, and may be performed multiple times as needed.

The stretching step is a treatment step of stretching the polyvinyl alcohol-based film in at least one direction at a predetermined magnification. Generally, a polyvinyl alcohol-type film is uniaxially stretched in a conveyance direction (longitudinal direction). The stretching method is not particularly limited, and either a wet stretching method or a dry stretching method may be employed. The said extending process may be performed only once, and may be performed multiple times as needed. The said extending process may be performed at any stage in manufacture of a polarizing film.

As the treatment bath (stretching bath) in the wet stretching method, a solvent such as water or a mixed solution of an organic solvent miscible with water and water can be used normally. The said stretching bath may contain potassium iodide from a viewpoint of controlling content of the said potassium in the said polarizing film. When using potassium iodide for the said drawing bath, it is preferable that the density|concentration of potassium iodide in the said drawing bath is about 1 to 15 weight%, It is more preferable that it is about 2 to 10 weight%, It is about 3 to 6 weight% It is more preferable that In addition, the treatment bath (stretching bath) may contain the boron compound from the viewpoint of suppressing film breakage during stretching. In this case, the concentration of the boron compound in the stretching bath is preferably about 1 to 15% by weight. And, it is more preferable that it is about 1.5 to 10 weight%, and it is more preferable that it is about 2 to 5 weight%.

It is preferable that the temperature of the said drawing bath is about 25-80 degreeC, It is more preferable that it is about 40-75 degreeC, It is more preferable that it is about 50-70 degreeC. The immersion time in the stretching bath cannot be determined collectively because the degree of stretching of the polyvinyl alcohol-based film is affected by the temperature of the stretching bath, but it is preferably about 10 to 800 seconds, and 30 to 500 seconds. It is more preferable that it is about. In addition, you may implement the extending|stretching process in the said wet extending|stretching method together with the treatment process of any one or more of the said swelling process, the said dyeing|staining process, the said bridge|crosslinking process, and the said washing|cleaning process.

Examples of the dry stretching method include an inter-roll stretching method, a heated roll stretching method, and a compression stretching method. In addition, you may implement the said dry stretching method together with the said drying process.

The total draw ratio (cumulative draw ratio) applied to the polyvinyl alcohol-based film can be appropriately set depending on the purpose, but it is preferably about 2 to 7 times, more preferably about 3 to 6.8 times, and 3.5 to It is more preferable that it is about 6.5 times.

The cleaning step is a treatment step in which the polyvinyl alcohol-based film is immersed in a cleaning bath, and foreign substances remaining on the surface of the polyvinyl alcohol-based film can be removed. As the washing bath, a medium mainly containing water such as water, distilled water, or pure water is used. In addition, potassium iodide may be included in the washing bath from the viewpoint of controlling the content of potassium in the polarizing film, and in this case, the concentration of potassium iodide in the washing bath is preferably about 1 to 10% by weight, and 1.5 It is more preferable that it is about -4 weight%, and it is still more preferable that it is about 1.8-3.8 weight%.

It is preferable that the temperature of the said washing|cleaning bath is about 5-50 degreeC, It is more preferable that it is about 10-40 degreeC, It is still more preferable that it is about 15-30 degreeC. The immersion time in the cleaning bath cannot be determined collectively because the degree of cleaning of the polyvinyl alcohol-based film is affected by the temperature of the cleaning bath, but it is preferably about 1 to 100 seconds, and 2 to 50 seconds. It is more preferable that it is about, and it is still more preferable that it is about 3 to 20 second. The said swelling process may be implemented only once, and may be implemented multiple times as needed.

The manufacturing method of the polarizing film of this invention may provide a drying process. The said drying process is a process of drying the polyvinyl alcohol-type film wash|cleaned in the said washing process, and obtaining a polarizing film, and the polarizing film which has a desired moisture content is obtained by drying. Said drying is performed by arbitrary suitable methods, for example, natural drying, air drying, and heat drying are illustrated.

It is preferable that it is about 20-150 degreeC, and, as for the said drying temperature, it is more preferable that it is about 25-100 degreeC. The drying time cannot be determined collectively because the degree of drying of the polarizing film is affected by the drying temperature, but is preferably about 10 to 600 seconds, and more preferably about 30 to 300 seconds. The said drying process may be performed only once, and may be performed multiple times as needed.

The polarizing film preferably has a thickness of 1 µm or more from the viewpoint of improving the initial polarization degree of the polarizing film, more preferably 2 µm or more, and preferably 20 µm or less from the viewpoint of preventing heat peeling, and more preferably 18 µm or less It is preferable, and it is more preferable that it is 15 micrometers or less. In particular, in order to obtain a polarizing film having a thickness of about 8 μm or less, the following method for producing a thin polarizing film using a laminate including a polyvinyl alcohol-based resin layer formed on a thermoplastic resin substrate as the polyvinyl alcohol-based film is applied. can

<Method for producing thin polarizing film>

A method for producing a thin polarizing film is to form a polyvinyl alcohol-based resin layer (PVA-based resin layer) containing a polyvinyl alcohol-based resin (PVA-based resin) on one side of a long thermoplastic resin substrate to obtain a laminate, and lamination It includes performing an aerial auxiliary extending|stretching process, a dyeing|staining process, an underwater extending|stretching process, and drying shrinkage process to a sieve in this order. In particular, in order to obtain a polarizing film having high optical properties, a method of two-stage stretching in which an air-assisted stretching treatment (dry stretching) and an underwater stretching treatment in an aqueous boric acid solution are combined is selected.

Any suitable method is employ|adopted as a method of producing the said laminated body, For example, the method is illustrated by apply|coating the coating liquid containing the said PVA-type resin to the surface of the said thermoplastic resin base material, and drying. It is preferable that it is about 20-300 micrometers, and, as for the thickness of the said thermoplastic resin base material, it is more preferable that it is about 50-200 micrometers. It is preferable that it is about 3-40 micrometers, and, as for the thickness of the said PVA-type resin layer, it is more preferable that it is about 3-20 micrometers.

The thermoplastic resin substrate absorbs water to significantly reduce the stretching stress, and from the viewpoint of being able to stretch at a high magnification, the water absorption is preferably about 0.2% or more, and more preferably about 0.3% or more. On the other hand, in the thermoplastic resin substrate, the dimensional stability of the thermoplastic resin substrate is remarkably reduced, and from the viewpoint of preventing problems such as deterioration of the appearance of the polarizing film obtained, the water absorption is preferably about 3% or less, and about 1% or less more preferably. In addition, the said water absorption rate can be adjusted by introduce|transducing a modifier into the constituent material of the said thermoplastic resin base material, for example. The said water absorption is a value calculated|required according to JISK7209.

The thermoplastic resin substrate preferably has a glass transition temperature (Tg) of about 120° C. or less from the viewpoint of sufficiently securing the stretchability of the laminate while suppressing crystallization of the PVA-based resin layer. Further, in consideration of plasticization of the thermoplastic resin substrate with water and good stretching in water, the glass transition temperature (Tg) is more preferably about 100° C. or less, and still more preferably about 90° C. or less. On the other hand, the glass transition temperature of the thermoplastic resin substrate is preferably about 60° C. or higher from the viewpoint of preventing problems such as deformation of the thermoplastic resin substrate during application and drying of the coating liquid and producing a good laminate. In addition, the said glass transition temperature can be adjusted by heating using the crystallization material which introduce|transduces a modifying group into the constituent material of the said thermoplastic resin base material, for example. The said glass transition temperature (Tg) is a value calculated|required according to JISK7121.

Any suitable thermoplastic resin may be employed as the constituent material of the thermoplastic resin substrate. Examples of the thermoplastic resin include ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, polyamide resins, polycarbonate resins, and these A copolymer resin etc. are illustrated. Among these, norbornene-based resins and amorphous (non-crystalline) polyethylene terephthalate-based resins are preferable, and the thermoplastic resin substrate is extremely excellent in stretchability and amorphous (amorphous) from the viewpoint that crystallization during stretching can be suppressed. ) A polyethylene terephthalate-based resin is preferably used. As the amorphous (non-crystalline) polyethylene terephthalate-based resin, a copolymer containing isophthalic acid and/or cyclohexanedicarboxylic acid as dicarboxylic acid, and a copolymer containing cyclohexanedimethanol or diethylene glycol as glycol is exemplified.

The thermoplastic resin substrate may be subjected to surface treatment (eg, corona treatment, etc.) before forming the PVA-based resin layer, or an easily adhesive layer may be formed on the thermoplastic resin substrate. By performing such a process, the adhesiveness of a thermoplastic resin base material and a PVA-type resin layer can be improved. In addition, the said thermoplastic resin base material may be extended|stretched before forming a PVA-type resin layer.

The coating solution is a solution in which a PVA-based resin is dissolved in a solvent. Examples of the solvent include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, ethylenediamine, and diethylenetriamine. Amines are illustrated, and water is preferable. These can be used individually or in combination of 2 or more types. The concentration of the PVA-based resin in the coating solution is preferably about 3 to 20 parts by weight based on 100 parts by weight of the solvent from the viewpoint of forming a uniform coating film in close contact with the thermoplastic resin substrate.

It is preferable that a halide is mix|blended with the said coating liquid from a viewpoint of improving the orientation of polyvinyl alcohol molecules by extending|stretching. Any suitable halide can be employ|adopted as said halide, For example, iodide, sodium chloride, etc. are illustrated. As said iodide, potassium iodide, sodium iodide, lithium iodide etc. are illustrated, for example, Potassium iodide is preferable. The concentration of the halide in the coating solution is preferably about 5 to 20 parts by weight, more preferably about 10 to 15 parts by weight, based on 100 parts by weight of the PVA-based resin.

Moreover, you may mix|blend an additive with the said coating liquid. As said additive, For example, plasticizers, such as ethylene glycol and glycerol; Surfactants, such as a nonionic surfactant, etc. are illustrated.

Any suitable method can be adopted as the coating method of the coating liquid, for example, a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, a die coating method, a curtain coating method, a spray coating method, and a knife. A coating method (comma coating method, etc.) etc. are illustrated. Moreover, it is preferable that the drying temperature of the said coating liquid is about 50 degreeC or more.

Since the above-mentioned aerial auxiliary stretching treatment enables stretching while suppressing crystallization of the thermoplastic resin substrate, the laminate can be stretched at a high magnification. The stretching method of the aerial auxiliary stretching treatment may be fixed-end stretching (eg, stretching using a tenter stretching machine), or free-end stretching (eg, uniaxial by passing a laminate between rolls having different peripheral speeds) stretching method) may be used, but free-end stretching is preferable from the viewpoint of obtaining high optical properties.

It is preferable that the draw ratio in the said aerial auxiliary extending|stretching is about 2-3.5 times. The said aerial auxiliary extending|stretching may be performed in one step, and may be performed in multiple steps. When carrying out in multiple steps, the draw ratio is the product of the draw ratios of each step.

The stretching temperature in the air-assisted stretching can be set to any appropriate value depending on the forming material of the thermoplastic resin substrate, the stretching method, etc., for example, it is preferably not less than the glass transition temperature (Tg) of the thermoplastic resin substrate, the glass It is more preferable that it is transition temperature (Tg) +10 degreeC or more, and it is still more preferable that it is the said glass transition temperature (Tg) +15 degreeC or more. On the other hand, the upper limit of the stretching temperature suppresses the rapid progress of crystallization of the PVA-based resin, and from the viewpoint of suppressing problems due to crystallization (eg, hindering the orientation of the PVA-based resin layer due to stretching). It is preferable that it is about 170 degreeC.

If necessary, you may perform an insolubilization process after the said aerial auxiliary extending|stretching process, before a dyeing|staining process or an underwater extending|stretching process. The insolubilization treatment is typically performed by immersing the PVA-based resin layer in an aqueous boric acid solution. By giving an insolubilization process, water resistance can be provided to a PVA-type resin layer, and the orientation fall of PVA at the time of being immersed in water can be prevented. The concentration of the boric acid aqueous solution is preferably about 1 to 5 parts by weight based on 100 parts by weight of water. It is preferable that the liquid temperature of an insolubilization treatment bath is about 20-50 degreeC.

The dyeing treatment is performed by dyeing the PVA-based resin layer with iodine. As the adsorption method, for example, a method of immersing a PVA-based resin layer (laminate) in a dyeing solution containing iodine, a method of applying the dyeing solution to the PVA-based resin layer, and applying the dyeing solution to a PVA-based resin layer The method of spraying etc. are illustrated, The method of immersing the PVA-type resin layer (laminated body) in the dyeing liquid containing iodine is preferable.

It is preferable that the compounding quantity of the iodine in the said dyeing bath is about 0.05-0.5 weight part with respect to 100 weight part of water. In order to increase the solubility of iodine in water, it is preferable to mix the iodide with an aqueous iodine solution. It is preferable that it is about 0.1-10 weight part with respect to 100 weight part of water, and, as for the compounding quantity of the said iodide, it is more preferable that it is about 0.3-5 weight part. It is preferable that the liquid temperature of a dyeing bath is about 20-50 degreeC in order to suppress dissolution of PVA-type resin. Moreover, it is preferable that they are about 5 second - about 5 minutes from a viewpoint of ensuring the transmittance|permeability of a PVA-type resin layer, and, as for immersion time, it is more preferable that they are about 30 second - 90 second. From a viewpoint of obtaining the polarizing film which has favorable optical properties, it is preferable that the ratio of content of iodine and iodide in an aqueous iodine solution is about 1:5-1:20, and it is more preferable that it is about 1:5-1:10.

If necessary, after the dyeing treatment, a crosslinking treatment may be performed before the underwater stretching treatment. The crosslinking treatment is typically performed by immersing the PVA-based resin layer in an aqueous boric acid solution. By performing a crosslinking process, water resistance can be provided to a PVA-type resin layer, and the orientation fall of PVA at the time of immersing in hot water by subsequent underwater extending|stretching can be prevented. The boric acid concentration of the boric acid aqueous solution is preferably about 1 to 5 parts by weight based on 100 parts by weight of water. In addition, when performing a crosslinking process, it is preferable to mix|blend the said iodide further in the crosslinking bath in a crosslinking process. By mix|blending the said iodide, the elution of the iodine made to adsorb|suck to the PVA-type resin layer can be suppressed. It is preferable that the compounding quantity of the said iodide is about 1-5 weight part with respect to 100 weight part of water. It is preferable that the liquid temperature of a crosslinking bath (boric acid aqueous solution) is about 20-50 degreeC.

The underwater stretching treatment is performed by immersing the laminate in a stretching bath. According to the underwater stretching treatment, stretching can be performed at a temperature lower than the glass transition temperature (typically, about 80° C.) of the thermoplastic resin substrate or the PVA-based resin layer, and the PVA-based resin layer is stretched at a high magnification while suppressing its crystallization. can do. The stretching method of the underwater stretching treatment may be fixed-end stretching (for example, a method of stretching using a tenter stretching machine), or free-end stretching (eg, uniaxial stretching by passing a laminate between rolls having different peripheral speeds) method) may be used, but free-end stretching is preferable from the viewpoint of obtaining high optical properties.

It is preferable to perform the said underwater extending|stretching process by immersing a laminated body in boric-acid aqueous solution (boric-acid water extending|stretching). By using the aqueous boric acid solution as the stretching bath, it is possible to impart rigidity to the PVA-based resin layer to withstand the tension applied during stretching and water resistance not to dissolve in water. It is preferable that it is 1-10 weight part with respect to 100 weight part of water, and, as for the boric acid concentration of boric-acid aqueous solution, it is more preferable that it is 2.5-6 weight part. In addition, you may mix|blend an iodide with the said extending|stretching bath (boric acid aqueous solution). It is preferable that it is about 40-85 degreeC, and, as for the liquid temperature of a drawing bath, it is more preferable that it is about 60 degreeC - 75 degreeC. It is preferable that the immersion time to the extending|stretching bath of a laminated body is about 15 second - about 5 minutes.

It is preferable that it is about 1.5 times or more, and, as for the draw ratio in the said underwater extending|stretching, it is more preferable that it is about 3 times or more.

Moreover, it is preferable that it is about 5 times or more with respect to the original length of a laminated body, and, as for the total draw ratio of a laminated body, it is more preferable that it is about 5.5 times or more.

Said drying shrinkage process may be performed by zone heating performed by heating the whole zone, and may be performed by heating a conveyance roll (a so-called heating roll is used), but both are preferably used. By drying using a heating roll, it is possible to efficiently suppress heating curl of the laminate to manufacture a polarizing film excellent in appearance, and also to keep the laminate in a flat state while drying it, thereby suppressing the occurrence of wrinkles as well as curls. can do. In addition, from the viewpoint of improving the optical properties of the polarizing film obtained by shrinking in the width direction during the drying shrinkage treatment, the shrinkage rate in the width direction of the laminate by the dry shrinkage treatment is preferably about 1 to 10%, and 2 to 8 % is more preferable.

Drying conditions are controllable by adjusting the heating temperature (temperature of a heating roll) of a conveyance roll, the number of heating rolls, contact time with a heating roll, etc. It is preferable that the temperature of a heating roll is about 60-120 degreeC, It is more preferable that it is about 65-100 degreeC, It is still more preferable that it is 70-80 degreeC. From the viewpoint that the degree of crystallinity of the thermoplastic resin can be satisfactorily increased and curling can be suppressed favorably, the number of conveying rolls is usually about 2 to 40, preferably about 4 to 30. It is preferable that it is about 1 to 300 second, as for the contact time (total contact time) of a laminated body and a heating roll, it is more preferable that it is 1 to 20 second, It is more preferable that it is 1 to 10 second.

A heating roll may be installed in a heating furnace, and may be installed in a normal production line (under a room temperature environment). Preferably, it is installed in the heating furnace provided with the ventilation means. By using together drying with a heating roll and hot air drying, the rapid temperature change between heating rolls can be suppressed, and the contraction|shrinkage of the width direction can be controlled easily. It is preferable that the temperature of hot air drying is about 30-100 degreeC. Moreover, it is preferable that hot air drying time is about 1-300 second.

It is preferable to perform a washing|cleaning process after an underwater extending|stretching process, but before a dry shrinkage process. The washing treatment is typically performed by immersing the PVA-based resin layer in an aqueous potassium iodide solution.

In addition, in the case of manufacturing a thin polarizing film containing the compound having the radical trapping function, at least one treatment bath of dyeing treatment, underwater stretching treatment, insolubilization treatment, crosslinking treatment, and washing treatment has the radical trapping function. What is necessary is just to contain a compound. The concentration of the compound having the radical trapping function contained in any one of the respective treatment baths cannot be determined collectively because it is affected by the number of treatments, treatment time, treatment temperature, etc. of each treatment, but the radical trapping function in the polarizing film From the viewpoint of being able to efficiently control the content of the compound having It is more preferable that it is 10 weight% or less, and it is still more preferable that it is 5 weight% or less.

In particular, in the case of carrying out the washing treatment, the washing treatment takes into account the treatment conditions in dyeing treatment and water stretching treatment, and then eluting components such as iodine or a compound having a radical trapping function from the polyvinyl alcohol-based film, or polyvinyl alcohol-based It is easy to adjust content of the said iodine and the compound which has the said radical trapping function to a desired range from a viewpoint of being able to make a film adsorb|suck.

Moreover, when manufacturing the thin polarizing film containing the compound which has the said radical trapping function, you may apply|coat and impregnate the polarizing film with the aqueous solution containing the compound which has the said radical trapping function. The application step may be provided before or after any of the dyeing treatment, the underwater stretching treatment, the insolubilization treatment, the crosslinking treatment, and the washing treatment, and in particular, from the viewpoint of easy adjustment of the content of the compound having the radical trapping function to a desired range. It is preferable to install after washing process. There is no restriction|limiting in particular as a coating method, For example, the wire bar coating method, the gravure coating method, the spray method etc. are illustrated.

In addition, additives such as zinc salt, pH adjuster, pH buffer, and other salts may be contained in each treatment bath in the dyeing treatment, water stretching treatment, insolubilization treatment, crosslinking treatment, and washing treatment. Examples of the zinc salt include zinc halides such as zinc chloride and zinc iodide; Inorganic zinc salts, such as zinc sulfate and zinc nitrate, etc. are illustrated. As said pH adjuster, strong acids, such as hydrochloric acid, sulfuric acid, nitric acid, and strong bases, such as sodium hydroxide and potassium hydroxide, are illustrated, for example. Examples of the pH buffer include carboxylic acids and salts thereof such as acetic acid, oxalic acid and citric acid, and weak inorganic acids and salts thereof such as phosphoric acid and carbonic acid. Examples of the other salts include chlorides such as sodium chloride, potassium chloride and barium chloride, nitrates such as sodium nitrate and potassium nitrate, sulfates such as sodium sulfate and potassium sulfate, and salts of alkali metals and alkaline earth metals. In particular, from the viewpoint of obtaining a polarizing film capable of suppressing a decrease in the single transmittance due to coloring of the polarizing film in a high-temperature environment, it is preferable that one or more treatment baths of each of the above treatment baths contain a chloride.

<Polarizing film>

The polarizing film of the present invention is a polarizing film in which a transparent protective film is bonded to both surfaces of the polarizing film, and at least one of the transparent protective film has a water vapor transmission rate of 200 g/(m 2 ·24h) or less, and general formula (1): ΔTs (%) ) = Ts ₇₅₀ -Ts ₀ (In the general formula (1), Ts ₀ is the single transmittance of the laminate in which a glass plate is bonded to one side of the polarizing film through an adhesive layer, and Ts ₇₅₀ is 105° C., 750 in the laminate It satisfies the condition that the amount of change (ΔTs) in the single transmittance expressed by the single transmittance after heat treatment with time is 0% or more and 5% or less.

<Transparent protective film>

The transparent protective film is not particularly limited as long as the water vapor transmission rate of the transparent protective film bonded to at least one surface of the polarizing film is 200 g/(m 2 ·24 h) or less, and various transparent protective films used for the polarizing film can be used. . As the material constituting the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like is used. Examples of the thermoplastic resin include cellulose ester-based resins such as triacetyl cellulose, polyester-based resins such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone-based resins, polysulfone-based resins, polycarbonate-based resins, nylon, Polyamide-based resin such as aromatic polyamide, polyimide-based resin, polyethylene, polypropylene, polyolefin-based resin such as ethylene/propylene copolymer, (meth)acrylic-based resin, cyclo-based or cyclic polyolefin-based resin having a norbornene structure (norbornene-based resin), polyarylate-based resin, polystyrene-based resin, polyvinyl alcohol-based resin, and mixtures thereof are exemplified. In addition, as the transparent protective film, a cured layer formed of a thermosetting resin or ultraviolet curable resin such as (meth)acrylic, urethane, acrylic urethane, epoxy, or silicone may be used. Among these, cellulose ester-type resin, polycarbonate-type resin, (meth)acrylic-type resin, cyclic polyolefin-type resin, and polyester-type resin are suitable.

Although the thickness of the transparent protective film can be appropriately determined, in general, it is preferably about 1-500 µm, more preferably about 1-300 µm, from the viewpoints of workability such as strength and handleability, thin layer properties, etc. , more preferably about 5 to 100 µm.

At least one side of the transparent protective film (the first transparent protective film on one side of the polarizer) has a water vapor transmission rate of 200 g/(m 2 ·24 h) or less, and a water vapor transmission rate of 180 g/( m 2 ·24h) or less, and more preferably 150 g/(m2·24h) or less. In addition, the other transparent protective film (the second transparent protective film on the other side of the polarizer) has a water vapor transmission rate of 200 g/(m 2 ·24h) or more from the viewpoint of production efficiency of the drying step after bonding the polarizing film and the transparent protective film. Preferably, it is more preferably 300 g/(m 2 ·24h) or more, and from the viewpoint of suppressing a decrease in the polarization degree of the polarizing film under a high temperature and high humidity environment, the water vapor transmission rate is preferably 1200 g/(m2·24h) or less, and 1000 g/(m2·24h) ) or less is more preferable. In addition, as for the moisture permeability, according to the moisture permeability test (cup method) of JIS Z0208, a sample cut to a diameter of 60 mm is set in a moisture-permeable cup containing about 15 g of calcium chloride, and placed in a thermostat at a temperature of 40° C. and a humidity of 90% R. H., for 24 hours It is computable by measuring the weight increase of calcium chloride before and behind leaving to stand.

When the said transparent protective film is laminated|attached on both surfaces of the said polarizing film, the transparent protective film of the both surfaces may be same or different.

As the transparent protective film, a retardation plate having a phase difference of 40 nm or more and/or a thickness direction retardation of 80 nm or more may be used. The front retardation is usually controlled in the range of 40 to 200 nm, and the thickness direction retardation is usually controlled in the range of 80 to 300 nm. When a retardation plate is used as the transparent protective film, since the retardation plate also functions as a transparent protective film, thickness reduction can be achieved.

Examples of the retardation plate include a birefringent film formed by subjecting a polymer material to uniaxial or biaxial stretching treatment, an alignment film of a liquid crystal polymer, and a film in which an alignment layer of a liquid crystal polymer is supported by a film. Although the thickness in particular of a retardation plate is not restrict|limited, About 20-150 micrometers is common. Further, the phase plate may be bonded to a transparent protective film having no phase difference to be used.

The transparent protective film may contain any appropriate additives such as an ultraviolet absorber, antioxidant, lubricant, plasticizer, mold release agent, color inhibitor, flame retardant, antistatic agent, pigment, and colorant.

Functional layers such as a hard coat layer, an anti-reflection layer, an anti-sticking layer, a diffusion layer or an anti-glare layer may be provided on the surface of the transparent protective film on which the polarizing film is not bonded. In addition, functional layers, such as the said hard coat layer, an antireflection layer, an anti-sticking layer, a diffusion layer, and an anti-glare layer, can be provided in the protective film, and can also be provided as a thing separate from a protective film.

The polarizing film and the transparent protective film, or the polarizing film and the functional layer are usually bonded through a pressure-sensitive adhesive layer or an adhesive layer.

As the pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer, various pressure-sensitive adhesives used for polarizing films can be applied, for example, a rubber-based pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive, a silicone pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a vinyl alkyl ether-based pressure-sensitive adhesive, a polyvinyl alcohol-based pressure-sensitive adhesive, a poly A vinyl porrolidone-type adhesive, a polyacrylamide-type adhesive, a cellulose-type adhesive, etc. are illustrated. Among these, an acrylic adhesive is suitable.

As a method of forming the pressure-sensitive adhesive layer, for example, a method in which the pressure-sensitive adhesive is applied to a peeling-treated separator or the like and dried to form a pressure-sensitive adhesive layer and then transferred to a polarizing film or the like, or the pressure-sensitive adhesive is applied to a polarizing film or the like and dried to the pressure-sensitive adhesive A method of forming a layer and the like can be exemplified. The thickness in particular of the said adhesive layer is not restrict|limited, For example, it is about 1-100 micrometers, and it is preferable that it is about 2-50 micrometers.

As the adhesive for forming the adhesive layer, various adhesives used in polarizing films can be applied, for example, isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latex-based adhesives, water-based polyesters, etc. do. These adhesives are usually used as adhesives made of an aqueous solution, and may contain 0.5 to 60% by weight of solid content.

As said adhesive agent, other than the above, active energy ray hardening adhesives, such as an ultraviolet curing adhesive and an electron beam curing adhesive, are illustrated. As said active energy ray hardening-type adhesive agent, a (meth)acrylate-type adhesive agent is illustrated, for example. As a curable component in the said (meth)acrylate-type adhesive agent, the compound which has a (meth)acryloyl group, and the compound which has a vinyl group are illustrated, for example. Moreover, the compound which has an epoxy group or oxetanyl group can also be used as a cationic polymerization hardening-type adhesive agent. The compound having an epoxy group is not particularly limited as long as it has at least two epoxy groups in the molecule, and various generally known curable epoxy compounds can be used.

Application of the said adhesive may be performed either to the said transparent protective film side (or the said functional layer side), and to the said polarizing film side, and may be performed to both. After bonding, a drying step is performed to form an adhesive layer comprising a coating and drying layer. After the drying step, if necessary, ultraviolet rays or electron beams can be irradiated. The thickness of the adhesive layer is not particularly limited, and when a water-based adhesive or the like is used, it is preferably about 30 to 5000 nm, more preferably about 100 to 1000 nm, and an ultraviolet curing adhesive, electron beam curing adhesive, etc. is used. In this case, it is preferable that it is about 0.1-100 micrometers, and it is more preferable that it is about 0.5-10 micrometers.

The transparent protective film and the polarizing film, or the polarizing film and the functional layer may be laminated through an intervening layer such as a surface modification treatment layer, an easily adhesive layer, a block layer, and a refractive index adjusting layer.

Examples of the surface modification treatment for forming the surface modification layer include corona treatment, plasma treatment, primer treatment, saponification treatment, and the like.

Examples of the easy-to-adhesive agent for forming the easily adhesive layer include various resins having a polyester skeleton, polyether skeleton, polycarbonate skeleton, polyurethane skeleton, silicone skeleton, polyamide skeleton, polyimide skeleton, polyvinyl alcohol skeleton, etc. A forming material that does this is exemplified. The said easily adhesive layer is normally provided in advance in a protective film, and the easily adhesive layer side of the said protective film and a polarizing film are laminated|stacked with the said adhesive layer or the said adhesive bond layer.

The blocking layer is a layer having a function to prevent impurities such as oligomers and ions eluted from the transparent protective film or the like from migrating (infiltrating) into the polarizing film. The block layer may be any layer that has transparency and can prevent impurities eluted from the transparent protective film or the like. As a material for forming the block layer, for example, a urethane prepolymer-based forming material, a cyanoacrylate-based forming material , an epoxy-based forming material, and the like.

The refractive index adjusting layer is a layer formed to suppress a decrease in transmittance due to reflection between layers having different refractive indices, such as the transparent protective film and the polarizing film. As a refractive index adjusting material which forms the said refractive index adjusting layer, the forming agent containing various resin and additives which have, for example, a silica type, an acryl type, an acryl-styrene type, a melamine type, etc. are illustrated.

The polarizing film of the present invention has the general formula (1): ΔTs (%) = Ts ₇₅₀ -Ts ₀ (in the general formula (1), Ts ₀ is a laminate in which a glass plate is bonded to one side of the polarizing film through an adhesive layer is the single transmittance of , and Ts ₇₅₀ represents the single transmittance after the laminate is heat-treated at 105° C. for 750 hours). Moreover, it is preferable that it is 0% or more and 3% or less, and, as for the change amount (ΔTs) of the said single transmittance, it is more preferable that it is 0% or more and 2% or less.

The polarization film preferably has a polarization degree of 99.98% or more, and more preferably a polarization degree of 99.99% or more.

<Laminated Polarizing Film>

As for the laminated polarizing film (optical laminated body) of this invention, the said polarizing film is bonded by the optical layer. The optical layer is not particularly limited, and for example, a reflective plate, a transflective plate, a retardation plate (including a wave plate such as 1/2 or 1/4), and a liquid crystal display device such as a visual compensation film One or two or more optical layers may be used. As the laminated polarizing film, in particular, a reflective polarizing film or a transflective polarizing film in which a reflecting plate or a transflective reflecting plate is further laminated on the polarizing film, an elliptically polarizing film or a circularly polarizing film in which a retardation plate is further laminated on the polarizing film; A wide viewing angle polarizing film formed by further laminating a visual compensation film on a polarizing film, or a polarizing film formed by further laminating a brightness enhancing film on the polarizing film is exemplified.

On one or both surfaces of the polarizing film or the laminated polarizing film, an image display cell such as a liquid crystal cell or an organic EL element, and a front transparent member such as a front transparent plate or a touch panel on the viewing side are other An adhesive layer for joining members may be laid. An adhesive layer is suitable as said adhesive bond layer. The pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer is not particularly limited, but for example, an acrylic polymer, silicone-based polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer as the base polymer is appropriately selected and used. can In particular, like the adhesive containing an acrylic polymer, it is excellent in optical transparency, shows suitable hygroscopicity, cohesiveness, and adhesiveness, and is excellent in weather resistance, heat resistance, etc. are used preferably.

Laying of the adhesive layer to one side or both surfaces of the said polarizing film or the said laminated|multilayer polarizing film can be performed by an appropriate method. As the laying of the pressure-sensitive adhesive layer, for example, a method of preparing an adhesive solution and directly laying it on the polarizing film or the laminated polarizing film by an appropriate development method such as a casting method or a coating method, or forming an adhesive layer on a separator and the method of attaching it on the said polarizing film or the said laminated polarizing film, etc. are illustrated. The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the purpose of use, adhesive strength, etc., and is generally 1 to 500 μm, preferably 5 to 200 μm, and more preferably 10 to 100 μm. Thus, let the thing in which the adhesive layer was formed in at least one surface of the said polarizing film or the said laminated polarizing film be a polarizing film with an adhesive layer, or a laminated polarizing film with an adhesive layer.

The exposed surface of the pressure-sensitive adhesive layer is preferably covered with a separator for the purpose of preventing contamination and the like until it is put into practical use. Thereby, contamination of the pressure-sensitive adhesive layer and the like under normal handling conditions can be prevented. As the separator, for example, a suitable thin leaf body such as a plastic film, rubber sheet, paper, cloth, nonwoven fabric, net, foam sheet, metal foil, laminates thereof, etc. Coated with an appropriate release agent for

<Image display panel and image display device>

As for the image display panel of this invention, the said polarizing film or the said laminated polarizing film is bonded by the image display cell. Moreover, the image display apparatus of this invention equips the polarizing film or laminated polarizing film side (viewing side) of the said image display panel with a front transparent member.

As said image display cell, a liquid crystal cell, organic electroluminescent cell, etc. are illustrated, for example. Examples of the liquid crystal cell include a reflective liquid crystal cell using external light, a transmissive liquid crystal cell using light from a light source such as a backlight, and a transflective liquid crystal cell using both light from the outside and light from the light source. you may use that In the case where the liquid crystal cell uses light from a light source, in the image display device (liquid crystal display device), a polarizing film is disposed on the side opposite to the viewing side of the image display cell (liquid crystal cell), and a light source is further disposed. It is preferable that the polarizing film and liquid crystal cell on the side of the said light source are bonded together through an appropriate adhesive bond layer. As a drive method of the said liquid crystal cell, the thing of arbitrary types, such as a VA mode, an IPS mode, a TN mode, an STN mode, and a band orientation ((pi) type|mold), can be used, for example.

As said organic electroluminescent cell, what laminated|stacked in order a transparent electrode, an organic light emitting layer, and a metal electrode on a transparent substrate, and formed the light emitting body (organic electroluminescent light emitting body) etc. are used suitably, for example. The organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative and a light emitting layer made of a fluorescent organic solid such as anthracene, or a layered product of these light emitting layers and a perylene derivative, etc. Various layer configurations, such as a laminate of electron injection layers, or a laminate of a hole injection layer, a light emitting layer, and an electron injection layer, can be employed.

As a front transparent member arrange|positioned on the visual recognition side of the said image display cell, a front transparent plate (window layer), a touch panel, etc. are illustrated, for example. As the front transparent plate, a transparent plate having an appropriate mechanical strength and thickness is used. As such a transparent plate, for example, a transparent resin plate such as an acrylic resin or polycarbonate resin, or a glass plate is used. As said touch panel, various touch panels, such as a resistive film method, a capacitive method, an optical method, and an ultrasonic method, a glass plate, a transparent resin board, etc. provided with a touch sensor function are used, for example. When a capacitive touch panel is used as the transparent plate, it is preferable that a front transparent plate made of glass or a transparent resin plate is provided on the viewing side more than the touch panel.

The polarizing film of the present invention has a good initial polarization degree, has an excellent effect of suppressing a decrease in the single transmittance due to coloring of the polarizing film under a high-temperature environment, and has an excellent inhibitory effect on a decrease in the degree of polarization under a high-temperature, high-humidity environment. Therefore, the polarizing film of this invention, the laminated polarizing film using the said polarizing film, an image display panel, and an image display apparatus are suitable for the use of vehicle-mounted image display apparatuses, such as a car navigation apparatus and a back monitor.

Example

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

<Example 1>

<Production of polarizing film>

A polyvinyl alcohol film having an average degree of polymerization of 2,400, a degree of saponification of 99.9 mol%, and a thickness of 30 µm was prepared. The polyvinyl alcohol film is immersed in a 20°C swelling bath (water bath) for 30 seconds between rolls with different circumferential speed ratios, and stretched 2.2 times in the conveying direction while swelling (swelling step), followed by a 30°C dyeing bath (water 100 weight) In the iodine aqueous solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with respect to parts), the iodine concentration of the finally obtained polarizing film is 3.8% by weight while adjusting the concentration so that the original polyvinyl alcohol is immersed for 30 seconds and dyed. It extended|stretched 3.3 times in the conveyance direction on the basis of the film (polyvinyl alcohol film which is not extended|stretched at all in the conveyance direction) (dyeing process). Next, the dyed polyvinyl alcohol film was immersed for 28 seconds in a crosslinking bath (boric acid concentration of 3.5 wt%, potassium iodide concentration of 3.0 wt%, and zinc sulfate concentration of 3.6 wt%) in a crosslinking bath at 40°C for 28 seconds to obtain the original polyvinyl alcohol. It extended|stretched up to 3.6 times in the conveyance direction on the basis of the film (crosslinking process). Further, the obtained polyvinyl alcohol film was immersed in a drawing bath at 64°C (aqueous solution having a boric acid concentration of 4.5% by weight, potassium iodide concentration of 5.0% by weight, and zinc sulfate concentration of 5.0% by weight) for 60 seconds to obtain the original polyvinyl alcohol film. After stretching up to 6.0 times in the conveying direction as a reference (stretching step), a cleaning bath at 27°C (potassium iodide concentration of 2.3% by weight, a compound having a radical trapping function, the compound concentration represented by the following general formula (9) is It was immersed for 10 second in 1.0 weight% aqueous solution) (washing process). The wash|cleaned polyvinyl alcohol film was dried at 40 degreeC for 30 second, and the polarizing film was produced. The iodine concentration of the polarizing film was calculated|required by the following measuring method. In addition, the obtained polarizing film has a dehydration temperature of polyenization (the peak temperature of the maximum intensity of water detected by the generated gas analysis method) of 210° C., and the content of the compound represented by the following general formula (9) in the polarizing film is 0.3% by weight, The thickness of the polarizing film was 12 μm.

[Method for Measuring Iodine Concentration (wt%) in Polarizing Film]

About the polarizing film, the iodine concentration (weight%) was calculated|required using the following formula using the fluorescence X-ray analyzer (The Rigaku Corporation make, brand name "ZSX-PRIMUS IV", measurement diameter: Ø20 mm).

Iodine concentration (wt%) = 14.474 × (fluorescence X-ray intensity) / (film thickness) (kcps/㎛)

In addition, although the coefficient at the time of calculating a density|concentration differs depending on the measuring apparatus, the said coefficient can be calculated|required using an appropriate calibration curve.

[Method for measuring dehydration temperature of polyenization]

A polarizing film was introduced into a furnace-type pyrolizer (manufactured by Frontier Laboratories Ltd., PY-2020iD), and the generated gas was directly introduced into TOFMS (manufactured by JEOL, MS-T100GCV), followed by analysis of the generated gas (EGA/TOFMS). The measurement was performed, the peak temperature of the maximum intensity of water to be detected was determined, and this temperature was set as the dehydration temperature for polyenization.

[Measuring conditions]

Temperature rise condition: 40℃→+10℃/min→350℃

Interface: Inert Fused Silica Tube, 2.5m×0.15mm id

Carrier gas: He (1.0 mL/min)

Inlet temperature: 300℃

Inlet: Split ratio 20:1

Interface temperature: 300℃

Mass Spectrometer: TOFMS

Ionization method: EI method

Mass range: m/z=18

[Method for measuring content (weight %) of a compound having a radical trapping function in a polarizing film]

About 20 mg of the polarizing film was collected, quantified, and dissolved by heating in 1 mL of water, diluted with 4.5 mL of methanol, and the resulting extract was filtered through a membrane filter, and the filtrate was filtered using HPLC (ACQUITY UPLC H-class Bio manufactured by Waters). The concentration of the compound having a radical trapping function was measured.

<Production of polarizing film>

As the adhesive, an aqueous solution containing a polyvinyl alcohol resin containing an acetoacetyl group (average degree of polymerization 1,200, saponification degree 98.5 mol%, acetoacetylation degree 5 mol%) and methylolmelamine in a weight ratio of 3:1 was used. Using this adhesive, HC was formed on a triacetyl cellulose film (manufactured by FUJIFILM Corporation, trade name "TJ40UL") as a second transparent protective film on one side (viewer side) of the polarizing film obtained above, and HC was formed, 47 µm thick, transparent A protective film (water vapor permeability of 380 g/(m 2 ·24h)) on the other side (image display cell side) as a first transparent protective film, (meth)acrylic resin (modified acrylic polymer having a lactone ring structure) 30 μm thick of a transparent protective film (manufactured by Nippon Shokubai Co., Ltd., moisture permeability of 125 g/(m 2 ·24 h)) was further bonded with a roll bonding machine, and then heated and dried in an oven (temperature of 90° C., time of 10 minutes) ) to prepare a polarizing film in which a transparent protective film was bonded to both surfaces of the polarizing film.

[Method for measuring single transmittance in a high-temperature environment]

The polarizing film obtained above is cut into a size of 5.0 x 4.5 cm so that the absorption axis of the polarizing film is parallel to the long side, and a glass plate (doctor) image display cell) was bonded, and the autoclave process was carried out at 50 degreeC and 0.5 MPa for 15 minutes, and the laminated body was produced. The obtained laminate was left still in a hot-air oven with a temperature of 105 degreeC for 750 hours, and the single transmittance ((DELTA)Ts) before and behind injection|throwing-in (heating) was measured. The single transmittance was measured using a spectrophotometer (manufactured by JASCO Corporation, product name "V7100"), and evaluated by the following standards. In addition, the measurement wavelength is 380-700 nm (every 5 nm). A result is shown in Table 1.

ΔTs(%)=Ts ₇₅₀ -Ts ₀

Here, Ts ₀ is the single transmittance of the laminate before heating, and Ts ₇₅₀ is the single transmittance of the laminate after heating for 750 hours.

[Evaluation of polarization degree]

The polarization degree of a polarizing film can be measured using the spectrophotometer (The JASCO Corporation make, product name "V7100"). As a specific method for measuring the degree of polarization, parallel transmittance (H0) and orthogonal transmittance (H90) of the polarizing film are measured, and from the formula: polarization degree (%) = {(H0-H90)/(H0+H90)}1/2×100 can be saved The parallel transmittance (H0) is a value of transmittance of a parallel laminated polarizing film prepared by stacking two identical polarizing films so that their absorption axes are parallel to each other. In addition, the orthogonal transmittance (H90) is a value of transmittance of an orthogonal laminated polarizing film prepared by superimposing two identical polarizing films so that their absorption axes are orthogonal to each other. In addition, these transmittance|permeability is the Y value which performed visibility correction|amendment with the 2 degree field of view (C light source) of JIS Z 8701-1982. A result is shown in Table 1.

[Evaluation of the humidification durability]

The polarization degree after leaving the said laminated body sample still for 500 hours in 85 degreeC and 85%RH moist-heat oven was evaluated with the said spectrophotometer (JASCO Corporation make, product name "V7100"). A result is shown in Table 1.

○: polarization degree 90% or more

x: polarization degree less than 90%

[Evaluation of heat peeling]

The polarizing film is cut to a size of 680 × 250 mm so that the absorption axis of the polarizing film is parallel to the long side, and a glass plate (pseudo image display cell) is passed through an acrylic pressure-sensitive adhesive layer having a thickness of 20 μm on the protective film side of the image display cell side of the polarizing film. has produced The following reference|standard visually evaluated the external appearance after leaving still for 750 hours in the 105 degree hot-air oven of the obtained laminated body sample. A result is shown in Table 1.

(circle): Although the edge part peels slightly, or foaming exists, there is no problem practically.

(triangle|delta): Although an edge part peels or foaming exists, unless there is a special use (For example, the distance from the edge part of a polarizing plate to the active area on which an image is short, the display of a narrow frame, etc.), there is no practical problem.

x: There is remarkable peeling at an edge part, and there exists a problem practically.

<Example 2>

<Preparation of polarizing film and polarizing film>

Preparation of a polarizing film WHEREIN: A polarizing film and a polarizing film were produced by operation similar to Example 1 except having adjusted the iodine concentration of a dyeing bath so that the iodine concentration of the polarizing film finally obtained might be set to 4.3 weight%. The obtained polarizing film had a peak temperature of the maximum intensity of water detected by the generated gas analysis method of 208° C., the content of the compound represented by the general formula (9) in the polarizing film was 0.3 wt %, and the thickness of the polarizing film was 12 μm.

<Example 3>

<Preparation of polarizing film and polarizing film>

In the production of the polarizing film, the polarizing film and A polarizing film was produced. The obtained polarizing film had a peak temperature of the maximum intensity of water detected by the generated gas analysis method of 210°C, the content of the compound represented by the above general formula (9) in the polarizing film was 0.2 wt%, and the thickness of the polarizing film was 18 µm.

<Example 4>

<Preparation of polarizing film and polarizing film>

In the preparation of the polarizing film, the iodine concentration of the dyeing bath is adjusted so that the iodine concentration of the finally obtained polarizing film is 4.8 wt%, and the potassium iodide concentration in the washing bath is 3.6 wt%, instead of the above general formula (9) A polarizing film and a polarizing film were produced by the operation method similar to Example 1 except having adjusted so that the compound represented by Formula (8) might become 1.5 weight%. The obtained polarizing film had a peak temperature of the maximum intensity of water detected by the generated gas analysis method of 210° C., the content of the compound represented by the general formula (8) in the polarizing film was 0.4 wt %, and the thickness of the polarizing film was 12 μm.

<Example 5>

<Preparation of polarizing film and polarizing film>

In the preparation of the polarizing film, the iodine concentration of the dyeing bath is adjusted so that the iodine concentration of the finally obtained polarizing film is 2.5% by weight, and the potassium iodide concentration in the washing bath is 1.8% by weight, instead of the above general formula (9), the following general A polarizing film and a polarizing film were produced by the operation method similar to Example 1 except having adjusted so that the compound represented by Formula (10) might become 1.0 weight% and sodium chloride might become 15 weight%. The obtained polarizing film has a peak temperature of the maximum intensity of water detected by the generated gas analysis method of 209°C, the content of the compound represented by the following general formula (10) in the polarizing film is 0.3% by weight, and the content of chlorine ions is 3.1% by weight, , the thickness of the polarizing film was 12 μm. In addition, the chlorine ion was calculated|required by the following measuring method.

[Method for measuring chlorine ions (chloride ions)]

5 mg of a sample was collect|collected in a polyenepropylene container, 20 mL of ultrapure water was added, and the lid was covered. Then, heating was performed at 120°C for 1 hour, and the resulting extract was filtered with a membrane filter and an organic matter removal cartridge, and chlorine ions were calculated by quantitative analysis by ion chromatography.

[Measuring conditions]

Apparatus (anion): ICS-3000 from Thermo Fisher Scientific

Separation column: Dionex IonPac AS18-fast (4 mm x 150 mm)

Guard column: Dionex IonPac AG18-fast (4 mm × 30 mm)

Removal System: Dionex AERS-500 (External Mode)

Detector: Electrical Conductivity Detector

Eluent: aqueous KOH solution (using eluent generator EGCIII)

Eluent flow rate: 1.2 mL/min

Sample injection volume: 250 μl

<Example 6>

<Preparation of polarizing film and polarizing film>

Creation of a polarizing film WHEREIN: A polarizing film and a polarizing film were produced by the operation method similar to Example 5 except not having added the compound represented by the said General formula (10). The obtained polarizing film had a peak temperature of the maximum intensity of water detected by the generated gas analysis method of 209°C, the content of chlorine ions in the polarizing film was 3.2% by weight, and the thickness of the polarizing film was 12 µm.

<Comparative Example 1>

<Preparation of polarizing film and polarizing film>

Preparation of a polarizing film WHEREIN: A polarizing film and a polarizing film were produced by operation similar to Example 2 except not having added the compound represented by the said General formula (9) as a compound which has a radical trapping function to a washing|cleaning bath. The obtained polarizing film had a peak temperature of the maximum intensity of water detected by the generated gas analysis method of 197 ° C., the content of the compound represented by the general formula (9) in the polarizing film was 0 wt%, and the thickness of the polarizing film was 12 µm.

<Comparative Example 2>

<Preparation of polarizing film and polarizing film>

In the preparation of the polarizing film, the iodine concentration of the dyeing bath is adjusted so that the iodine concentration of the polarizing film finally obtained is 2.5% by weight, and the compound represented by the general formula (9) as a compound having a radical trapping function in the washing bath A polarizing film and a polarizing film were produced by operation similar to Example 1 except not adding. The obtained polarizing film had a peak temperature of the maximum intensity of water detected by the generated gas analysis method of 206° C., the content of the compound represented by the general formula (9) in the polarizing film was 0% by weight, and the thickness of the polarizing film was 12 μm.

<Comparative Example 3>

<Preparation of polarizing film and polarizing film>

Polarized light in the same manner as in Example 1, except that a triacetyl cellulose film (KONICA MINOLTA, INC., trade name "KC2CT") having a thickness of 20 µm and a water vapor transmission rate of 1270 g/(m 2 ·24 h) was used for the first transparent protective film film was made

<Comparative Example 4>

<Preparation of polarizing film and polarizing film>

In the production of the polarizing film, a polyvinyl alcohol film having a thickness of 75 μm is immersed in a swelling bath (water bath) at 35° C. between rolls having different circumferential speed ratios for 30 seconds, and stretched 2.2 times in the conveying direction while swelling (swelling step), The iodine concentration of the dyeing bath was adjusted so that the iodine concentration of the finally obtained polarizing film was 3.1% by weight, 3% by weight of sodium chloride was added to the washing bath, and the first transparent protective film had a thickness of 20 μm and a water vapor transmission rate of 1270 g/m2 · A polarizing film and a polarizing film were produced in the same manner as in Comparative Example 1 except that a 24 hr triacetyl cellulose film (KONICA MINOLTA, INC., trade name "KC2CT") was used. The obtained polarizing film had a peak temperature of the maximum intensity of water detected by the generated gas analysis method of 209°C, the content of chlorine ions in the polarizing film was 1.1% by weight, and the thickness of the polarizing film was 28 µm.

Using the polarizing film of each Example and each comparative example obtained above, the above [Method for measuring single transmittance in a high temperature environment], [Evaluation of polarization degree], [Evaluation of humidification durability], and [Evaluation of heat peeling] did A result is shown in Table 1.

Claims (11)

A polarizing film in which a transparent protective film is bonded to both sides of a polarizing film,
The polarizing film is formed by adsorption orientation of iodine on a polyvinyl alcohol-based film, and an iodine concentration of 3% by weight or more and 10% by weight or less,
At least one of the transparent protective films has a moisture permeability of 200 g/(m 2 ·24h) or less,
The polarizing film has the general formula (1): ΔTs(%)=Ts ₇₅₀ -Ts ₀
(In the general formula (1), Ts ₀ is the single transmittance of a laminate in which a glass plate is bonded to one side of the polarizing film through an adhesive layer, and Ts ₇₅₀ is a simple substance after the laminate is heat-treated at 105° C. for 750 hours. The polarizing film which satisfies the condition that the amount of change (ΔTs) of the single transmittance represented by the transmittance is 0% or more and 5% or less. The method of claim 1,
The polarizing film is a polarizing film, characterized in that the thickness is 20㎛ or less. 3. The method of claim 1 or 2,
The polarizing film is characterized in that it contains a compound having a radical trapping function. 4. The method of claim 3,
The polarizing film, characterized in that the compound having a radical trapping function is a compound having a nitroxy radical or a nitroxide group. 5. The method according to any one of claims 1 to 4,
The polarizing film is characterized in that it contains chlorine ions. 6. The method of claim 5,
The polarizing film, characterized in that the content of the chlorine ion is more than 2% by weight of the polarizing film. 7. The method according to any one of claims 1 to 6,
A polarizing film, characterized in that the degree of polarization is 99.98% or more. The polarizing film in any one of Claims 1-7 is bonded by the optical layer, The laminated polarizing film characterized by the above-mentioned. The polarizing film in any one of Claims 1-7, or the laminated polarizing film of Claim 8 is bonded by the image display cell, The image display panel characterized by the above-mentioned. A front transparent member is provided on the polarizing film or laminated polarizing film side of the image display panel of Claim 9, The image display apparatus characterized by the above-mentioned. 11. The method of claim 10,
An image display device for use in a vehicle.