TW202116544A - Polarizing film, laminated polarizing film, image display panel, and image display device - Google Patents

Abstract

A polarizing film in which transparent protective films are bonded to both sides of the polarizing film, wherein the polarizing film is formed by adsorbing and orienting iodine on a polyvinyl alcohol-based film and has an iodine concentration of 6 wt% or more, at least one of the transparent protective films has a moisture permeability of 200 g/(m2.24 h) or less, and the polarizing film satisfies the condition that the amount of change ([Delta]Ts) of a single transmittance represented by a general formula (1): [Delta]Ts (%) = Ts750 - Ts0 is 0-5% (inclusive). The polarizing film has a good initial degree of polarization, excels in suppressing a decrease in the single transmittance due to coloring of the polarizing film in a high-temperature environment, and also excels in suppressing a decrease in the degree of polarization in a high-temperature and high-humidity environment.

Description

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

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

In the past, polarizing films used in various image display devices such as liquid crystal display devices or organic EL display devices have been dyed (containing iodine or dichroic dyes, etc.) for the reason of having both high transmittance and high polarization. Color material) polyvinyl alcohol film. This polarizing film is manufactured by subjecting the polyvinyl alcohol-based film to various treatments such as swelling, dyeing, crosslinking, and stretching in a bath, followed by washing treatment and drying. In addition, the aforementioned polarizing film is usually used as a polarizing film (polarizing plate) in which a protective film such as cellulose triacetate is bonded to one or both sides using an adhesive.

The aforementioned polarizing film can be laminated with other optical layers to form a laminated polarizing film (optical laminate) to use, and the aforementioned polarizing film or the aforementioned laminated polarizing film (optical laminate) is bonded through an adhesive layer or an adhesive layer. Between the image display unit such as a liquid crystal cell or an organic EL element and a front transparent member such as a front transparent plate (window layer) or a touch panel on the viewing side, the various image display devices described above are used (Patent Document 1).

In recent years, the various image display devices described above have been used in mobile devices such as mobile phones or tablet terminals, as well as in-vehicle image display devices such as car navigation devices and rear-illuminated monitors, and have a wide range of applications. Therefore, the aforementioned image display device is required to have high durability in a harsher environment (for example, under a high temperature environment) than conventionally required, and an image display device for the purpose of ensuring the durability is proposed (Patent Document 2). Prior art literature Patent literature

Patent Document 1: Japanese Patent Laid-Open No. 2014-102353 Patent Document 2: Japanese Patent Laid-Open No. 2018-101117

The problem to be solved by the invention When the polarizing film or laminated polarizing film using iodine-based polarizing film is exposed to high temperature, the polyvinyl alcohol that constitutes the polarizing film will be polyalkenized due to the dehydration reaction, causing the polarizing film to be colored, and its monomer transmittance is reduced. The problem.

Through active research, the inventors of the present invention found that iodine contained in the iodine-based polarizing film promotes polyethylenization under a high-temperature environment. Therefore, if it is desired to suppress the decrease in the transmittance of the monomer due to the coloring of the polarizing film in a high temperature environment, it is effective to reduce the iodine concentration (content) in the polarizing film. On the other hand, it is difficult to obtain a polarizing film with a good degree of polarization and a high iodine concentration.

In addition, when the polarizing film or the laminated polarizing film is in a high temperature and high humidity environment, the crosslinking of boric acid in the polarizing film will fall off, causing the iodine complex to be destroyed, and there is a problem that the degree of polarization decreases.

In view of the above situation, the purpose of the present invention is to provide a polarizing film with a polarizing film with a high iodine concentration to provide a polarizing film with the following polarizing film. The effect of reducing the volume transmittance is good, and the effect of suppressing the decrease of polarization degree (humidification durability) is good in a high temperature and high humidity environment.

Moreover, an object of the present invention is to provide a laminated polarizing film, an image display panel, and an image display device using the above-mentioned polarizing film.

The means to solve the problem, that is, the present invention relates to a polarizing film, which is laminated with a transparent protective film on both sides of the polarizing film; the polarizing film is formed by adsorbing and oriented iodine on the polyvinyl alcohol film, and the iodine concentration The moisture permeability of at least one of the aforementioned transparent protective films is less than 200g/(m ² ·24h); the aforementioned polarizing film satisfies the general formula (1): ΔTs _{(%)=Ts 750 -Ts 0} The condition that the change in monomer transmittance (ΔTs) is 0% or more and 5% or less (in the aforementioned general formula (1), Ts ₀ is a laminate in which a glass plate is attached to one side of the polarizing film through an adhesive layer) The monomer transmittance of the body, Ts ₇₅₀ represents the monomer transmittance of the aforementioned laminate after heat treatment at 95°C for 750 hours).

In addition, the present invention relates to a laminated polarizing film obtained by bonding the aforementioned polarizing film to an optical layer.

In addition, the present invention relates to an image display panel, which is bonded with the aforementioned polarizing film or the aforementioned laminated polarizing film to an image display unit.

Furthermore, the present invention relates to an image display device which is provided with a front transparent member on the polarizing film or laminated polarizing film side of the aforementioned image display panel.

Invention effect Although the details of the mechanism of the effect of the polarizing film of the present invention are still unclear, we speculate as follows. However, the present invention may not be limited to the explanation of the mechanism of action.

The polarizing film of the present invention is one with a transparent protective film laminated on both sides of the polarizing film; the polarizing film is formed by adsorbing and oriented iodine on the polyvinyl alcohol film, and the iodine concentration is 6 wt% or more; of the transparent protective film The moisture permeability of at least one of them is 200g/(m ² ·24h) or less; the aforementioned polarizing film satisfies the general formula (1): ΔTs _{(%)=Ts 750 -Ts 0} The amount of change in the transmittance of the monomer (ΔTs) is Conditions of 0% or more and 5% or less (in the above general formula (1), Ts ₀ is the monomer transmittance of the laminated body with the glass plate bonded to the adhesive layer on one side of the polarizing film, and Ts ₇₅₀ represents the above The monomer transmittance of the laminate after heat treatment at 95°C for 750 hours). The polarizing film of the present invention has a small change in monomer transmittance (ΔTs) after the above-mentioned heat treatment (under a high temperature environment), so it can suppress the coloring of the polarizing film to reduce the monomer transmittance. Therefore, we speculate that the reason why the change in monomer transmittance (ΔTs) before and after the heat treatment is small is that the temperature of the dehydration reaction caused by the polyolefinization of the polarizing film of the present invention is higher than that of the conventional polarizing film. In particular, the above-mentioned heating treatment is a heating endurance test as a heat resistance index of a vehicle display, which is more stringent than the previous heating endurance test. In addition, the polarizing film of the present invention sets the iodine concentration in the polarizing film within a certain range, so that the temperature of initiating polyolefinization and leading to the dehydration reaction can be controlled to the high temperature side, and the initial polarization degree is good.

In addition, in the polarizing film of the present invention, the moisture permeability of at least one of the transparent protective films is 200g/(m ² · 24h) or less, so water can be prevented from entering the polarizing film, thereby suppressing polarized light even in a high temperature and high humidity environment The effect of lowering the degree of humidity (humidification durability) is still good.

The form used to implement the invention ＜Polarizing film＞ The polarizing film of the present invention is an iodine-based polarizing film formed by adsorbing and oriented iodine on a polyvinyl alcohol-based film, and the iodine concentration is 6 wt% or more. The above-mentioned polyvinyl alcohol (PVA)-based film can be used without particular limitation, which has translucency in the visible light region and can dispersely adsorb iodine. In addition, the thickness of the PVA-based film generally used as the original plate is preferably about 1 to 100 μm, preferably about 1 to 50 μm, and the width is preferably about 100 to 5000 mm.

Examples of the material of the polyvinyl alcohol-based film include polyvinyl alcohol or derivatives thereof. Examples of the aforementioned derivatives of polyvinyl alcohol include polyvinyl formal and polyvinyl acetal; olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid and their alkyl esters, and amide acrylates. Waiting for reformers, etc. The average degree of polymerization of the aforementioned polyvinyl alcohol is preferably about 100 to 10,000, preferably about 1,000 to 10,000, and more preferably about 1,500 to 4,500. In addition, the degree of saponification of the aforementioned polyvinyl alcohol is preferably about 80 to 100 mol%, preferably about 95 mol% to 99.95 mol%. In addition, the aforementioned average polymerization degree and the aforementioned saponification degree can be obtained in accordance with JIS K 6726.

The aforementioned polyvinyl alcohol-based film may also contain additives such as plasticizers and surfactants. Examples of the plasticizer include polyhydric alcohols such as glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol, and polyethylene glycol, and condensates thereof. The use amount of the aforementioned additives is not particularly limited, but for example, it is preferably about 20% by weight or less in a polyvinyl alcohol-based film.

In the aforementioned polarizing film, the iodine concentration (content) is 6 wt% or more from the viewpoint of making the initial polarization degree of the polarizing film good. In the aforementioned polarizing film, from the viewpoint of increasing the initial polarization degree of the polarizing film, the aforementioned iodine concentration (content) is preferably greater than 6 wt%, more preferably 7 wt%, and more preferably 8 wt% or more. From the viewpoint that the temperature of the dehydration reaction due to olefination becomes a high temperature, it is preferably 12% by weight or less, and more preferably 10% by weight or less.

系化合物等具有自由基捕捉功能之化合物。由可易將引發多烯化之脫水反應的溫度設定在高溫側之觀點來看，前述具有自由基捕捉功能之化合物例如宜為具有氮氧自由基或氮氧基之化合物。前述具有自由基捕捉功能之化合物可單獨使用亦可將2種以上併用。The aforementioned polarizing film preferably contains a compound having a radical trapping function. We speculate that the aforementioned compound with free radical trapping function will trap the free radicals generated by heating of the polyvinyl alcohol of the polarizing film, and the temperature for initiating the dehydration reaction of polyalkylene can be set to the high temperature side. The aforementioned compounds with a free radical trapping function can include, for example, hindered phenols, hindered amines, phosphorus, sulfur, benzotriazole, diphenylketone, hydroxylamine, salicylate, and three

It is a compound with free radical trapping function, such as a compound. From the viewpoint that the temperature of the dehydration reaction for initiating polyolefination can be easily set to the high temperature side, the aforementioned compound having a radical trapping function is preferably a compound having a nitroxide radical or a nitroxyl group. The aforementioned compounds having a radical trapping function may be used alone or in combination of two or more kinds.

…(1) (通式(1)中，R¹ 表示氧自由基，R² 至R⁵ 獨立表示氫原子或碳原子數1~10烷基，n表示0或1)。此外，通式(1)中虛線部之左邊表示任意的有機基。The aforementioned compounds with nitroxyl radicals or nitroxyl radicals are considered to have free radicals that are relatively stable at room temperature and in the air, and N-oxyl compounds (with CN(-C)-O· as a functional group) The compound (O・represents oxygen radical)), and known ones can be used. The aforementioned compound having a nitroxide radical or a nitroxyl group includes, for example, a compound having an organic group of the following structure. [Chemical formula 1]

...(1) (In the general formula (1), R ¹ represents an oxygen radical, R ² to R ⁵ independently represent a hydrogen atom or an alkyl group with 1 to 10 carbon atoms, and n represents 0 or 1). In addition, the left side of the dotted line in the general formula (1) represents an arbitrary organic group.

…(2) (通式(2)中，R¹ ~R⁵ 及n與上述相同，R⁶ 表示氫原子或碳原子數1~10烷基、醯基或芳基，n表示0或1)。 [化學式3]

…(3) (通式(3)中，R¹ 至R⁵ 及n與上述相同，R⁷ 及R⁸ 獨立表示氫原子或碳原子數1~10烷基、醯基或芳基)。 [化學式4]

…(4) (通式(4)中，R¹ 至R⁵ 及n與上述相同，R⁹ 至R¹¹ 獨立表示氫原子或碳原子數1~10烷基、醯基、胺基、烷氧基、羥基或芳基)。 [化學式5]

…(5) (通式(5)中，R¹ 至R⁵ 及n與上述相同，R¹² 表示氫原子或碳原子數1~10烷基、胺基、烷氧基、羥基或芳基)。Examples of the compound having the above-mentioned organic group include compounds represented by the following general formulas (2) to (5). [Chemical formula 2]

…(2) (In the 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 with 1 to 10 carbon atoms, and n represents 0 or 1) . [Chemical formula 3]

...(3) (In the general formula (3), R ¹ to R ⁵ and n are the same as described 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). [Chemical formula 4]

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

...(5) (In the 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 with 1 to 10 carbon atoms, an amino group, an alkoxy group, a hydroxyl group or an aryl group) .

In the aforementioned general formulas (1) to (5), R ² to R ⁵ are preferably an alkyl group having 1 to 6 carbon atoms, and more preferably an alkyl group having 1 to 3 carbon atoms, from the viewpoint of ease of acquisition. Furthermore, in the aforementioned general formula (2), from the viewpoint of ease of acquisition, R ^{6 is} preferably a hydrogen atom or an alkyl group with 1 to 10 carbon atoms, and a hydrogen atom is more preferred. Moreover, in the aforementioned general formula (3), from the viewpoint of ease of acquisition, R ⁷ and R ^{8 are} preferably independently a hydrogen atom or an alkyl group with 1 to 10 carbon atoms, and a hydrogen atom is preferred. In addition, in the aforementioned general formula (4), R ⁹ to R ^{11 are} preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms from the viewpoint of ease of acquisition. In addition, in the aforementioned general formula (5), R ^{12 is} preferably a hydroxyl group, an amino group or an alkoxy group from the viewpoint of ease of acquisition. In the aforementioned general formulas (1) to (5), n is preferably 1 from the viewpoint of ease of acquisition.

…(6) (通式(6)中，R表示氫原子或碳原子數1~10烷基、醯基或芳基)。 [化學式7]

…(7) [化學式8]

…(8)In addition, examples of the compound having a nitroxide radical or a nitroxyl group include the following compounds. [Chemical formula 6]

...(6) (In the general formula (6), R represents a hydrogen atom or an alkyl group, acyl group, or aryl group having 1 to 10 carbon atoms). [Chemical formula 7]

…(7) [Chemical formula 8]

…(8)

In addition, from the viewpoint of efficiently trapping free radicals generated in the polyolefination reaction, the molecular weight of the aforementioned compound having a radical trapping function is preferably 1000 or less, preferably 500 or less, and more preferably 300 or less.

In addition, the aforementioned compound with a radical trapping function is preferably a water-soluble compound that can dissolve at least 1 part by weight with respect to 100 parts by weight of water at 25°C from the viewpoint of water that easily moves into the polarizing film. It is preferable that 100 parts by weight of water can dissolve 2 parts by weight or more of water-soluble compounds, and it is more preferable to dissolve more than 5 parts by weight of water-soluble compounds relative to 100 parts by weight of water at 25°C.

From the viewpoint of suppressing the decrease in the transmittance of the monomer due to the coloring of the polarizing film in a high temperature environment, when the polarizing film contains the compound having the free radical trapping function, the content of the compound having the free radical trapping function is in the polarizing film It is preferably 0.01% by weight or more, preferably 0.02% by weight or more, more preferably 0.05% by weight or more. From the viewpoint of appearance, it is preferably 10% by weight or less, preferably 7% by weight or less, and more preferably 3% by weight or less.

The aforementioned polarizing film preferably contains chloride ions (chloride ions). We speculate that the aforementioned chloride ions are deliquescent, which can delay the dehydration reaction of the polyvinyl alcohol of the polarizing film due to heating, so that the temperature of the dehydration reaction that initiates polyolefinization can be set to the high temperature side.

When the aforementioned polarizing film contains chloride ions (chloride ions), the content of the aforementioned chloride ions in the aforementioned polarizing film is preferably 0.1% by weight or more from the viewpoint of suppressing the reduction of monomer transmittance caused by the coloring of the polarizing film in a high-temperature environment. 0.5% by weight or more is preferable, 1% by weight or more is more preferable, and more than 2% by weight is even more preferable. From the viewpoint of the hue change of the polarizing film in a high temperature environment, it is preferably 10% by weight or less and 7% by weight or less Preferably, it is more preferably 5% by weight or less.

＜Manufacturing method of polarizing film＞ The manufacturing method of the aforementioned polarizing film is obtained by subjecting the aforementioned polyvinyl alcohol-based film to any swelling step and washing step, and at least performing a dyeing step, a cross-linking step, and a stretching step. The content of the aforementioned iodine contained in the aforementioned polarizing film can be determined by the concentration of the aforementioned iodine and potassium iodide and other iodides contained in any one of the treatment baths in the swelling step, the dyeing step, the cross-linking step, the stretching step, and the washing step. The treatment temperature and treatment time of each treatment bath mentioned above are controlled.

In addition, when manufacturing a polarizing film containing the compound having a radical trapping function, any one or more of the swelling step, the washing step, the dyeing step, the crosslinking step, and the stretching step need to be contained in any one or more treatment baths. The aforementioned compound having the function of capturing radicals is sufficient. The concentration of the aforementioned compound with free radical trapping function contained in any of the aforementioned treatment baths will be affected by the number of treatments, treatment time, treatment temperature, etc., so it cannot be determined unambiguously, but the polarizing film can be controlled efficiently From the viewpoint of the content of the compound having a free radical trapping function in the above, it is usually preferably 0.03% by weight or more, preferably 0.05% by weight or more, more preferably 0.1% by weight or more, and preferably 15% by weight or less, 10% by weight % Or less is preferable, and 5% by weight or less is more preferable.

Especially when the washing step is performed after the dyeing step, the cross-linking step, and the extension step, taking into account the processing conditions of the dyeing step, cross-linking step, and extension step, the iodine or the aforementioned free radical trapping From the viewpoint of elution or adsorption of functional compounds and other components to the polyvinyl alcohol-based film, the cleaning step can easily adjust the content of the aforementioned iodine or the aforementioned compound having a radical-trapping function to a desired range.

In addition, when manufacturing a polarizing film containing the aforementioned compound having a radical trapping function, it is also possible to apply an aqueous solution containing the aforementioned compound having a radical trapping function to infiltrate the polarizing film. The coating step can be set before and after any one of the above-mentioned swelling step, dyeing step, cross-linking step, extension step, and washing treatment. In particular, the content of the aforementioned compound with free radical trapping function can be easily adjusted to the desired level. From the point of view of scope, it should be set after the washing step. The coating method is not particularly limited, and examples thereof include a wire bar coating method, a gravure coating method, and a spray coating method.

In addition, each treatment bath in the aforementioned swelling step, the aforementioned dyeing step, the aforementioned cross-linking step, the aforementioned extension step, and the aforementioned washing step may also contain additives such as zinc salt, pH adjusting agent, pH buffering agent, and other salts. Examples of the aforementioned zinc salt include zinc halides such as zinc chloride and zinc iodide; and inorganic zinc salts such as zinc sulfate and zinc acetate. Examples of the pH adjuster include strong acids such as hydrochloric acid, sulfuric acid, and nitric acid, or strong bases such as sodium hydroxide and potassium hydroxide. Examples of the aforementioned pH buffering agent include carboxylic acids and their salts such as acetic acid, oxalic acid, and citric acid, or weak inorganic acids such as phosphoric acid and carbonic acid and their salts. The aforementioned other salts include, for example, chlorides such as sodium chloride, potassium chloride, and barium chloride, nitrates such as sodium nitrate, potassium nitrate, sulfates such as sodium sulfate, potassium sulfate, and salts of alkali metals and alkaline earth metals. Wait. In particular, from the viewpoint of obtaining a polarizing film capable of suppressing the decrease in the transmittance of the monomer due to coloring of the polarizing film in a high-temperature environment, it is preferable that one or more of the above-mentioned treatment baths contain a chloride.

The aforementioned swelling step is a processing step of immersing the polyvinyl alcohol-based film in a swelling bath, which can remove dirt and anti-caking agents on the surface of the polyvinyl alcohol-based film, and can swell the polyvinyl alcohol-based film to suppress uneven dyeing. The aforementioned swelling bath generally can use water, distilled water, pure water and other media with water as the main component. The aforementioned swelling bath can also be appropriately added with surfactants, alcohols, etc. according to general methods.

The temperature of the aforementioned swelling bath is preferably about 10-60°C, preferably about 15-45°C, and more preferably about 18-30°C. In addition, since the degree of swelling of the polyvinyl alcohol-based film is affected by the temperature of the swelling bath, the immersion time for immersion in the aforementioned swelling bath cannot be determined uniformly. It is preferably about 5 to 300 seconds, preferably about 10 to 200 seconds. , 20~100 seconds is better. The aforementioned swelling step can be implemented only once, or multiple times as needed.

The aforementioned dyeing step is a processing step of immersing the polyvinyl alcohol-based film in a dyeing bath (iodine solution), which can adsorb and orient iodine to the polyvinyl alcohol-based film. The aforementioned iodine solution is generally an iodine aqueous solution, and contains iodine and iodide as a dissolution aid. In addition, the aforementioned iodide may include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, titanium iodide, etc. . Among these, from the viewpoint of controlling the potassium content in the aforementioned polarizing film, potassium iodide is preferable.

In the aforementioned dyeing bath, the iodine concentration is preferably about 0.01 to 1% by weight, preferably about 0.02 to 0.5% by weight. In the aforementioned dyeing bath, the concentration of the aforementioned iodide is preferably about 0.01-20% by weight, preferably about 0.05-10% by weight, and more preferably about 0.1-5% by weight.

The temperature of the aforementioned dyeing bath is preferably about 10-50°C, preferably about 15-45°C, and more preferably about 18-30°C. In addition, since the degree of dyeing of the polyvinyl alcohol-based film is affected by the temperature of the dyeing bath, the immersion time for immersion in the aforementioned dyeing bath cannot be determined uniformly, and it is preferably about 10 to 300 seconds, preferably about 20 to 240 seconds . The aforementioned dyeing step can be performed only once, or multiple times as needed.

The aforementioned cross-linking step is a treatment step in which the polyvinyl alcohol-based film is immersed in a treatment bath (cross-linking bath) containing a boron compound. The polyvinyl alcohol-based film can be cross-linked through the boron compound to adsorb iodine molecules or dye molecules to The cross-linked structure. Examples of the aforementioned boron compound include boric acid, borate, and borax. The aforementioned crosslinking bath is generally an aqueous solution, but for example, it may be a mixed solution of an organic solvent and water that is miscible with water. In addition, from the viewpoint of controlling the potassium content in the polarizing film, the cross-linking bath preferably contains potassium iodide.

In the aforementioned crosslinking bath, the concentration of the aforementioned boron compound is preferably about 1 to 15% by weight, preferably about 1.5 to 10% by weight, and more preferably about 2 to 5% by weight. Furthermore, when potassium iodide is used in the cross-linking bath, the concentration of potassium iodide in the cross-linking bath is preferably about 1 to 15% by weight, preferably about 1.5 to 10% by weight, and more preferably about 2 to 5% by weight.

The temperature of the aforementioned crosslinking bath is preferably about 20 to 70°C, preferably about 30 to 60°C. In addition, since the degree of crosslinking of the polyvinyl alcohol-based film is affected by the temperature of the crosslinking bath, the immersion time for immersion in the aforementioned crosslinking bath cannot be determined uniformly, but is preferably about 5 to 300 seconds, 10 to 200 seconds Left and right are better. The aforementioned cross-linking step can be performed only once, or multiple times as needed.

The aforementioned stretching step is a processing step of stretching the polyvinyl alcohol-based film in at least one direction at a predetermined magnification. In general, the polyvinyl alcohol-based film is uniaxially stretched in the conveying direction (long-side direction). The aforementioned extension method is not particularly limited, and any one of a wet extension method and a dry extension method can be used. The aforementioned extension step can be performed only once, or multiple times as needed. The aforementioned stretching step can be performed at any stage in the manufacture of the polarizing film.

The treatment bath (extension bath) of the aforementioned wet extension method generally can use a solvent such as water or an organic solvent miscible with water and a mixed solution of water. From the viewpoint of controlling the potassium content in the polarizing film, the stretching bath may also contain potassium iodide. When potassium iodide is used in the aforementioned extension bath, the concentration of potassium iodide in the extension bath is preferably about 1-15% by weight, preferably about 2-10% by weight, and more preferably about 3-6% by weight. In addition, from the viewpoint of suppressing film breakage during stretching, the treatment bath (stretching bath) may contain the boron compound. In this case, the concentration of the boron compound in the stretching bath is preferably about 1-15% by weight, 1.5-10 About weight% is preferable, and about 2 to 5 weight% is more preferable.

The temperature of the aforementioned extension bath is preferably about 25-80°C, preferably about 40-75°C, and more preferably about 50-70°C. Also, since the degree of extension of the polyvinyl alcohol-based film is affected by the temperature of the extension bath, the immersion time for immersion in the aforementioned extension bath cannot be determined at all. It is preferably about 10 to 800 seconds, preferably about 30 to 500 seconds. . In addition, the stretching treatment of the aforementioned wet stretching method can also be performed together with any one or more treatment steps of the aforementioned swelling step, the aforementioned dyeing step, the aforementioned cross-linking step, and the aforementioned washing step.

Examples of the aforementioned dry stretching method include an inter-roll stretching method, a heated roll stretching method, and a compression stretching method. In addition, the aforementioned dry stretching method can also be performed together with the aforementioned drying step.

The total stretching ratio (cumulative stretching ratio) applied to the aforementioned polyvinyl alcohol-based film can be appropriately set according to the purpose, and is preferably about 2 to 7 times, preferably about 3 to 6.8 times, and more preferably about 3.5 to 6.5 times.

The aforementioned washing step is a processing step of immersing the polyvinyl alcohol-based film in a washing bath, which can remove foreign substances remaining on the surface of the polyvinyl alcohol-based film. The aforementioned washing bath generally can use a medium containing water as the main component, such as water, distilled water, and pure water. In addition, from the viewpoint of controlling the potassium content in the polarizing film, the washing bath may also contain potassium iodide. At this time, the concentration of potassium iodide in the washing bath is preferably about 1-10% by weight, 1.5-4% by weight About% is preferable, and about 1.8 to 3.8% by weight is more preferable.

The temperature of the aforementioned washing bath is preferably about 5-50°C, preferably about 10-40°C, and more preferably about 15-30°C. In addition, since the degree of washing of the polyvinyl alcohol-based film is affected by the temperature of the washing bath, the immersion time for immersion in the aforementioned washing bath cannot be determined uniformly. It is preferably about 1-100 seconds, 2-50 seconds Left and right are better, preferably about 3 to 20 seconds. The aforementioned swelling step can be implemented only once, or multiple times as needed.

The manufacturing method of the polarizing film of the present invention can also be provided with a drying step. The aforementioned drying step is a step of drying the polyvinyl alcohol-based film washed in the aforementioned washing step to obtain a polarizing film, and a polarizing film having a desired moisture content can be obtained by drying. The aforementioned drying can be performed by any appropriate method, and examples thereof include natural drying, air blowing drying, and heat drying.

The aforementioned drying temperature is preferably about 20 to 150°C, preferably about 25 to 100°C. In addition, since the degree of drying of the polarizing film will be affected by the drying temperature, the aforementioned drying time cannot be determined at all. It is preferably about 10 to 600 seconds, preferably about 30 to 300 seconds. The aforementioned drying step can be performed only once, or multiple times as needed.

From the viewpoint of increasing the initial polarization of the polarizing film, the thickness of the aforementioned polarizing film is preferably 1 μm or more, preferably 2 μm or more, and from the viewpoint of preventing panel warpage, it is preferably 15 μm or less, preferably 10 μm or less. 8μm or less is more preferable. In particular, in order to obtain a polarizing film with a thickness of about 8μm or less, the following thin polarizing film manufacturing method can be applied. The thin polarizing film uses a laminate including a polyvinyl alcohol-based resin layer formed by forming a film on a thermoplastic resin substrate as the aforementioned Polyvinyl alcohol-based film.

＜Manufacturing method of thin polarizing film＞ The manufacturing method of the thin polarizing film includes the following steps: forming a polyvinyl alcohol resin layer (PVA resin layer) containing a polyvinyl alcohol resin (PVA resin) on one side of a long-shaped thermoplastic resin substrate, and the product is made Laminated body; and, the laminated body is sequentially subjected to aerial auxiliary stretching treatment, dyeing treatment, underwater stretching treatment and drying shrinkage treatment. Especially in order to obtain a polarizing film with high optical properties, a two-stage stretching method combining aerial auxiliary stretching treatment (dry stretching) and water stretching treatment in a boric acid aqueous solution is selected.

Any appropriate method can be adopted for the method of producing the laminate. For example, a method of applying a coating liquid containing the PVA-based resin to the surface of the thermoplastic resin substrate and drying it can be mentioned. The thickness of the aforementioned thermoplastic resin substrate is preferably about 20 to 300 μm, preferably about 50 to 200 μm. The thickness of the aforementioned PVA-based resin layer is preferably about 3-40 μm, preferably about 3-20 μm.

From the standpoint of the aforementioned thermoplastic resin substrate that can absorb water and greatly reduce the elongation stress so as to extend at a high magnification, the water absorption is preferably about 0.2% or more, preferably about 0.3% or more. On the other hand, from the viewpoint of preventing the dimensional stability of the thermoplastic resin substrate from being significantly reduced and causing the deterioration of the appearance of the polarizing film obtained, the water absorption rate of the thermoplastic resin substrate is preferably about 3% or less. About% or less is better. In addition, the water absorption rate can be adjusted, for example, by introducing a modifying group into the constituent material of the thermoplastic resin substrate. The aforementioned water absorption is a value obtained in accordance with JIS K 7209.

From the viewpoint of suppressing the crystallization of the PVA-based resin layer and ensuring the extensibility of the laminate, the glass transition temperature (Tg) of the aforementioned thermoplastic resin substrate is preferably about 120°C or less. In addition, considering the use of water to plasticize the thermoplastic resin substrate and the ability to stretch well in water, the glass transition temperature (Tg) is preferably about 100°C or less, and preferably about 90°C or less. On the other hand, from the viewpoint of preventing defects such as deformation of the thermoplastic resin substrate during coating and drying of the coating solution and producing a good laminate, the glass transition temperature of the thermoplastic resin substrate is preferably about 60°C or higher . In addition, the glass transition temperature can be adjusted by heating, for example, by using a crystallization material that can introduce a modifying group into the constituent material of the thermoplastic resin substrate. The aforementioned glass transition temperature (Tg) is a value obtained in accordance with JIS K 7121.

Any appropriate thermoplastic resin can be used as the constituent material of the aforementioned thermoplastic resin substrate. The aforementioned thermoplastic resins include, for example, ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, polyamide resins, and polycarbonate resins. And other copolymer resins. Among them, norbornene-based resins and amorphous (amorphous) polyethylene terephthalate-based resins are preferred, and from the viewpoint of excellent extensibility and suppression of crystallization during stretching For the thermoplastic resin substrate, it is better to use amorphous (amorphous) polyethylene terephthalate resin. Amorphous (amorphous) polyethylene terephthalate resins may include copolymers containing isophthalic acid and/or cyclohexanedicarboxylic acid as dicarboxylic acids, or containing cyclohexanedimethanol Or diethylene glycol as a copolymer of glycol.

The aforementioned thermoplastic resin substrate may be subjected to surface treatment (for example, corona treatment, etc.) before forming the PVA-based resin layer, or an easy-adhesion layer may be formed on the thermoplastic resin substrate. By performing the treatment, the adhesion between the thermoplastic resin substrate and the PVA-based resin layer can be improved. In addition, the aforementioned thermoplastic resin substrate may be stretched before forming the PVA-based resin layer.

The aforementioned coating liquid is a solution in which PVA-based resin is dissolved in a solvent. Examples of the aforementioned solvent include water, dimethyl sulfide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, trimethylolpropane and other polyols, extensions Amines such as ethylenediamine and diethylenetriamine are preferably water. These can be used alone or in combination of two or more kinds. From the viewpoint of forming a uniform coating film adhered to the thermoplastic resin substrate, the concentration of the PVA-based resin in the coating solution is preferably about 3 to 20 parts by weight relative to 100 parts by weight of the solvent.

From the viewpoint that the orientation of polyvinyl alcohol molecules can be improved by extension, it is preferable to blend a halide in the aforementioned coating liquid. Any appropriate halide can be used as the aforementioned halide, and examples thereof include iodide and sodium chloride. Examples of the aforementioned iodide include potassium iodide, sodium iodide, and lithium iodide, and potassium iodide is preferred. The concentration of the halide in the coating solution is preferably about 5-20 parts by weight, preferably about 10-15 parts by weight, relative to 100 parts by weight of the PVA-based resin.

In addition, additives may be blended in the aforementioned coating liquid. Examples of the aforementioned additives include plasticizers such as ethylene glycol or glycerol; and surfactants such as nonionic surfactants.

As an example of the coating method of the aforementioned coating liquid, any appropriate method can be used, such as roll coating, spin coating, wire bar coating, dip coating, die coating, curtain coating, spray coating, and doctor blade. Type coating method (comma coating method, etc.) and so on. In addition, the drying temperature of the aforementioned coating liquid is preferably about 50°C or higher.

The aforementioned air-assisted stretching treatment step can stretch while suppressing the crystallization of the thermoplastic resin base material, so that the laminate can be stretched at a high magnification. The stretching method of the aforementioned aerial auxiliary stretching treatment can be fixed-end stretching (for example, stretching using a tenter stretching machine) or free-end stretching (for example, uniaxial stretching of the laminated body through rollers with different peripheral speeds) Method), and from the viewpoint of obtaining high optical characteristics, it is better to extend the free end.

The extension ratio of the aforementioned aerial auxiliary extension should be about 2~3.5 times. The aforementioned aerial auxiliary extension can be carried out in one stage or in multiple stages. When it is carried out in multiple stages, the stretching ratio is the product of the stretching ratios of each stage.

The stretching temperature of the aforementioned aerial auxiliary stretching can be set to any appropriate value according to the forming material of the thermoplastic resin substrate, the stretching method, etc., for example, preferably above the glass transition temperature (Tg) of the thermoplastic resin substrate, the aforementioned glass transition temperature (Tg) +10°C or higher is preferable, and the aforementioned glass transition temperature (Tg) +15°C or higher is more preferable. On the other hand, from the viewpoint of suppressing the rapid progress of the crystallization of the PVA-based resin and suppressing the defects caused by the crystallization (for example, hindering the orientation of the PVA-based resin layer due to extension), the upper limit of the extension temperature is preferably Around 170°C.

It is also possible to perform the insolubilization treatment after the aforementioned aerial auxiliary extension treatment and before the dyeing treatment or the underwater extension treatment according to needs. The aforementioned insolubilization treatment means that the PVA-based resin layer is immersed in an aqueous boric acid solution. The insolubilization treatment can impart water resistance to the PVA-based resin layer and prevent the orientation of the PVA from decreasing when immersed in water. The concentration of the boric acid aqueous solution is preferably about 1 to 5 parts by weight relative to 100 parts by weight of water. The liquid temperature of the insoluble treatment bath should be about 20~50℃.

The aforementioned dyeing treatment is performed by dyeing the PVA-based resin layer with iodine. The adsorption method includes, for example, a method of immersing the PVA-based resin layer (layered body) in a dyeing solution containing iodine, a method of coating the dyeing solution on the PVA-based resin layer, and spraying the dyeing solution onto the PVA The method on the resin layer, etc., is preferably a method of immersing the PVA resin layer (layered body) in a dyeing solution containing iodine.

The blending amount of iodine in the aforementioned dyeing bath is preferably about 0.05 to 0.5 parts by weight with respect to 100 parts by weight of water. In order to improve the solubility of iodine in water, it is advisable to mix the aforementioned iodide with the iodine aqueous solution. The blending amount of the aforementioned iodide is preferably about 0.1 to 10 parts by weight, preferably about 0.3 to 5 parts by weight, relative to 100 parts by weight of water. In order to prevent the PVA-based resin from dissolving, the liquid temperature of the dyeing bath is preferably about 20-50°C. In addition, from the viewpoint of ensuring the transmittance of the PVA-based resin layer, the immersion time is preferably about 5 seconds to 5 minutes, and more preferably about 30 seconds to 90 seconds. From the viewpoint of obtaining a polarizing film with good optical properties, the content ratio of iodine and iodide in the iodine aqueous solution is preferably about 1:5 to 1:20, preferably about 1:5 to 1:10.

It can also be cross-linked after dyeing treatment and before extension treatment in water as needed. The aforementioned crosslinking treatment is typically performed by immersing the PVA-based resin layer in a boric acid aqueous solution. The cross-linking treatment can impart water resistance to the PVA-based resin layer and prevent the orientation of the PVA from being reduced when it is immersed in high-temperature water in the subsequent water extension. The boric acid concentration of the boric acid aqueous solution is preferably about 1 to 5 parts by weight relative to 100 parts by weight of water. In addition, when the crosslinking treatment is performed, it is preferable to further blend the aforementioned iodide in the crosslinking bath of the crosslinking treatment. By blending the aforementioned iodide, it is possible to suppress the elution of iodine that has been adsorbed on the PVA-based resin layer. The blending amount of the aforementioned iodide is preferably about 1 to 5 parts by weight relative to 100 parts by weight of water. The temperature of the cross-linking bath (aqueous solution of boric acid) should be around 20~50°C.

The aforementioned underwater stretching treatment is performed by immersing the laminate in a stretching bath. The stretching treatment in water can stretch at a temperature lower than the glass transition temperature of the thermoplastic resin substrate or PVA resin layer (typically around 80°C), and can suppress the crystallization of the PVA resin layer at the same time Perform high-magnification extension. The stretching method of the aforementioned underwater stretching treatment can be fixed-end stretching (for example, a method of stretching using a tenter stretcher) or free-end stretching (for example, a method of uniaxially stretching the laminated body through rollers with different peripheral speeds) ), and from the viewpoint of obtaining high optical properties, it is better to extend the free end.

The aforementioned underwater stretching treatment is preferably performed by immersing the layered body in a boric acid aqueous solution (boric acid aqueous stretching). By using an aqueous solution of boric acid as a stretching bath, rigidity and water-insoluble water resistance can be imparted to the PVA-based resin layer to withstand the tension applied during stretching. The boric acid concentration of the boric acid aqueous solution is preferably 1-10 parts by weight, preferably 2.5-6 parts by weight relative to 100 parts by weight of water. In addition, iodide may be blended in the aforementioned stretching bath (aqueous boric acid solution). The temperature of the extension bath should be about 40~85℃, preferably about 60℃~75℃. The immersion time for the laminate to be immersed in the extension bath is preferably about 15 seconds to 5 minutes.

The stretching ratio of the aforementioned underwater stretching is preferably about 1.5 times or more, preferably about 3 times or more.

In addition, the total stretching ratio of the laminated body is preferably about 5 times or more, and more preferably about 5.5 times or more relative to the original length of the laminated body.

The aforementioned drying and shrinking treatment can be performed by heating the area by heating the entire area, or by heating the conveying roller (so-called using a heating roller). It is preferable to use both. By using a heating roller to dry it, heating and curling of the laminated body can be effectively suppressed, and a polarizing film with excellent appearance can be produced. The laminated body can be dried while maintaining a flat state, so not only curling can be suppressed. It can also suppress wrinkling. In addition, during the drying and shrinking treatment, by shrinking it in the width direction, the optical properties of the obtained polarizing film can be improved. From this point of view, the shrinkage rate in the width direction of the laminate due to the drying and shrinking treatment is preferably About 1~10%, 2~8% is better.

By adjusting the heating temperature of the conveying roller (temperature of the heating roller), the number of heating rollers and the contact time with the heating roller, etc., the drying conditions can be controlled. The temperature of the heating roller is preferably around 60~120℃, preferably around 65~100℃, more preferably 70~80℃. From the viewpoint of improving the degree of crystallinity of the thermoplastic resin and suppressing curling well, the conveyor rollers are generally set at about 2 to 40, and preferably set at about 4 to 30. The contact time (total contact time) between the laminate and the heating roller is preferably about 1 to 300 seconds, preferably 1 to 20 seconds, and more preferably 1 to 10 seconds.

The heating roller can be installed in a heating furnace or in a general manufacturing line (under room temperature). It is suitable to be installed in a heating furnace equipped with an air supply mechanism. By combining drying with heating rollers and hot air drying, sudden temperature changes between the heating rollers can be suppressed, and the shrinkage in the width direction can be easily controlled. The temperature of hot air drying should be around 30~100℃. In addition, the hot air drying time is preferably about 1 to 300 seconds.

It is advisable to perform a washing treatment after the water extension treatment and before the drying shrinkage treatment. The aforementioned washing treatment is typically performed by immersing the PVA-based resin layer in a potassium iodide aqueous solution.

In addition, when manufacturing a thin polarizing film containing the compound with the aforementioned free radical trapping function, it is only necessary that any one or more of the dyeing treatment, underwater stretching treatment, insolubilization treatment, cross-linking treatment, and cleaning treatment contains the aforementioned compound Compounds with free radical capture function are sufficient. The concentration of the aforementioned compound with free radical trapping function contained in any of the aforementioned treatment baths will be affected by the number of treatments, treatment time, treatment temperature, etc., so it cannot be determined unambiguously, but the polarizing film can be controlled efficiently From the viewpoint of the content of the compound having a free radical trapping function in the above, it is usually preferably 0.03% by weight or more, preferably 0.05% by weight or more, more preferably 0.1% by weight or more, and preferably 15% by weight or less, 10% by weight % Or less is preferable, and 5% by weight or less is more preferable.

Especially in the case of washing treatment, taking into account the treatment conditions such as dyeing treatment, water extension treatment, etc., components such as iodine or the aforementioned free radical trapping function can be eluted from the polyvinyl alcohol-based film or From the viewpoint of adsorption to the polyvinyl alcohol-based film, it is easy to adjust the content of the aforementioned iodine or the aforementioned compound having a radical trapping function to a desired range in the washing treatment.

In addition, when manufacturing a thin polarizing film containing the aforementioned compound having a radical trapping function, it is also possible to apply an aqueous solution containing the aforementioned compound having a radical trapping function to infiltrate the polarizing film. The coating step can be set before and after any one of the above-mentioned dyeing treatment, water extension treatment, insolubilization treatment, cross-linking treatment and washing treatment, especially by adjusting the content of the aforementioned compound with free radical trapping function to the desired From the point of view of the range, it should be set after the washing treatment. The coating method is not particularly limited, and examples thereof include a wire bar coating method, a gravure coating method, and a spray coating method.

In addition, the above-mentioned dyeing treatment, water extension treatment, insolubilization treatment, cross-linking treatment, and washing treatment may also contain additives such as zinc salt, pH adjuster, pH buffer, and other salts. Examples of the aforementioned zinc salt include zinc halides such as zinc chloride and zinc iodide; and inorganic zinc salts such as zinc sulfate and zinc acetate. Examples of the pH adjuster include strong acids such as hydrochloric acid, sulfuric acid, and nitric acid, or strong bases such as sodium hydroxide and potassium hydroxide. Examples of the aforementioned pH buffering agent include carboxylic acids and their salts such as acetic acid, oxalic acid, and citric acid, or weak inorganic acids such as phosphoric acid and carbonic acid and their salts. The aforementioned other salts include, for example, chlorides such as sodium chloride, potassium chloride, and barium chloride, nitrates such as sodium nitrate, potassium nitrate, sulfates such as sodium sulfate, potassium sulfate, and salts of alkali metals and alkaline earth metals. Wait. In particular, from the viewpoint of obtaining a polarizing film capable of suppressing the decrease in the transmittance of the monomer due to coloring of the polarizing film in a high-temperature environment, it is preferable that one or more of the above-mentioned treatment baths contain a chloride.

<Polarizing film> The polarizing film of the present invention is one with transparent protective films laminated on both sides of the aforementioned polarizing film; the moisture permeability of at least one of the aforementioned transparent protective films is 200g/(m ² · 24h) or less; the polarizing film satisfies Formula (1): ΔTs _{(%)=Ts 750 -Ts 0} shows that the change in monomer transmittance (ΔTs) is 0% or more and 5% or less (in the aforementioned general formula (1), Ts ₀ is The monomer transmittance of the laminated body in which the glass plate is bonded to one side of the polarizing film through the adhesive layer. Ts ₇₅₀ represents the monomer transmittance of the laminated body after heat treatment at 95°C for 750 hours).

<Transparent protective film> As long as the transparent protective film is bonded to at least one side of the polarizing film, the moisture permeability of the transparent protective film is 200g/(m ²・24h) or less. There is no particular limitation. Various types of polarizing films can be used. Transparent protective film. As the material constituting the aforementioned transparent protective film, for example, thermoplastic resins excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, and isotropy can be used. Examples of the thermoplastic resin include: cellulose ester resins such as cellulose triacetate, polyester resins such as polyethylene terephthalate or polyethylene naphthalate, polyether-based resins, and poly-based resins. , Polycarbonate resins, polyamide resins such as nylon or aromatic polyamides, polyimide resins, polyolefin resins such as polyethylene, polypropylene, ethylene and propylene copolymers, (methyl) Acrylic resin, cyclic or cyclic polyolefin resin having a norbornene structure (norbornene resin), polyarylate resin, polystyrene resin, polyvinyl alcohol resin, and mixtures thereof. In addition, the aforementioned transparent protective film can be cured using thermosetting resins such as (meth)acrylic, urethane, acrylic urethane, epoxy, polysilicone, or ultraviolet curable resins. Floor. Among these, cellulose ester resins, polycarbonate resins, (meth)acrylic resins, cyclic polyolefin resins, and polyester resins are preferable.

The thickness of the aforementioned transparent protective film can be appropriately determined, but generally from the viewpoints of workability such as strength or handling, thin layer properties, etc., it is preferably about 1 to 500 μm, preferably about 1 to 300 μm, and more preferably about 5 to 100 μm.

At least one of the aforementioned transparent protective films (the first transparent protective film on one side of the polarizer) has a moisture permeability of 200g/(m ² · 24h) or less, which suppresses the degree of polarization of the polarizing film in a high-temperature and high-humidity environment From the viewpoint of reduction, the moisture permeability is preferably 180g/(m ² ·24h) or less, ^{preferably 150g/(m 2} ·24h) or less. In addition, from the viewpoint of production efficiency in the drying step after bonding the polarizing film and the transparent protective film, the moisture permeability of the other transparent protective film (the second transparent protective film on the other side of the polarizing member) is preferably 200 g/( m ² ·24h) or more, 300g/(m ² ·24h) or more is preferable. From the viewpoint of suppressing the decrease in the degree of polarization of the polarizing film in a high-temperature and high-humidity environment, the moisture permeability is preferably 1200g/(m ² · 24h) or less, ^{preferably 1000g/(m 2} ·24h) or less. In addition, the moisture permeability can follow the moisture permeability test of JIS Z0208 (cup method). The sample cut to a diameter of 60mm is placed in a moisture permeable cup containing about 15g of calcium chloride and placed in the temperature In a thermostat with a temperature of 40°C and a humidity of 90%RH, the weight gain of calcium chloride before and after being left for 24 hours was measured to calculate it.

When the transparent protective film is attached to both sides of the polarizing film, the transparent protective films on both sides may be the same or different.

As the aforementioned transparent protective film, a retardation plate having a frontal retardation of 40 nm or more and/or a retardation of 80 nm or more in the thickness direction can be used. The frontal phase difference is usually controlled in the range of 40~200nm, and the thickness direction phase difference is usually controlled in the range of 80~300nm. When a phase difference plate is used as the above-mentioned transparent protective film, the phase difference plate can also function as a transparent protective film, so that it can be reduced in thickness.

As the above-mentioned retardation plate, for example, a birefringent film obtained by uniaxially or biaxially stretching a polymer material, an oriented film of a liquid crystal polymer, a film supporting an oriented layer of a liquid crystal polymer, etc. are mentioned. The thickness of the phase difference plate is not particularly limited, and is generally about 20 to 150 μm. In addition, it can also be used by pasting the aforementioned phase plate on a transparent protective film without phase difference.

The aforementioned transparent protective film may also contain any appropriate additives such as ultraviolet absorbers, antioxidants, slip agents, plasticizers, release agents, anti-colorants, flame retardants, antistatic agents, pigments, and colorants.

Functional layers such as a hard coat layer, an anti-reflection layer, an anti-adhesion layer, a diffusion layer or an anti-glare layer can be provided on the surface of the aforementioned transparent protective film that is not attached to the polarizing film. In addition, functional layers such as the above-mentioned hard coat layer, anti-reflection layer, anti-adhesion layer, diffusion layer, or anti-glare layer may be provided in addition to the protective film itself, or may be separately provided as an individual from the protective film.

The aforementioned polarizing film and the aforementioned transparent protective film, or the aforementioned polarizing film and the aforementioned functional layer are generally bonded through an adhesive layer or an adhesive layer.

The adhesive that forms the aforementioned adhesive layer can be applied to various adhesives that can be used for polarizing films, such as rubber-based adhesives, acrylic adhesives, silicone-based adhesives, urethane-based adhesives, and vinyl alkanes. Base ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, cellulose-based adhesives, etc. Among them, acrylic adhesive is preferable.

The method of forming the adhesive layer can be exemplified by the following method: the aforementioned adhesive is applied to a peeled-off part, etc., dried to form an adhesive layer, and then transferred to a polarizing film, etc.; The adhesive is applied to a polarizing film, etc., and dried to form an adhesive layer. The thickness of the aforementioned adhesive layer is not particularly limited, and is, for example, about 1 to 100 μm, and preferably about 2 to 50 μm.

Various adhesives that can be used for polarizing films can be applied to the adhesive forming the aforementioned adhesive layer, and examples thereof include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latex-based, water-based polyesters, and the like. These adhesives are usually used as an adhesive composed of an aqueous solution and contain 0.5 to 60% by weight of solid content.

In addition to the above-mentioned adhesives, active energy ray-curable adhesives such as ultraviolet-curable adhesives and electron beam-curable adhesives can be cited. Examples of the active energy ray-curable adhesive agent include (meth)acrylate-based adhesive agents. Examples of the curable component of the (meth)acrylate-based adhesive include a compound having a (meth)acryloyl group and a compound having a vinyl group. Moreover, the cationic polymerization hardening type adhesive agent can also use the compound which has an epoxy group or an oxetanyl group. 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.

The application of the adhesive may be performed on either the transparent protective film side (or the functional layer side) and the polarizing film side, or both. After bonding, a drying step is performed to form an adhesive layer composed of a coated dry layer. After the aforementioned drying step, ultraviolet light or electron beam can be irradiated as needed. The thickness of the aforementioned adhesive layer is not particularly limited. When using water-based adhesives, etc., it is preferably about 30 to 5000 nm, preferably about 100 to 1000 nm. When using ultraviolet curing type adhesives, electron beam curing type adhesives, etc., It is preferably about 0.1 to 100 μm, preferably about 0.5 to 10 μm.

The transparent protective film and the polarizing film, or the polarizing film and the functional layer may also be laminated via intermediary layers such as a surface modification layer, an easy-adhesive layer, a barrier layer, and a refractive index adjustment layer.

The surface modification treatment for forming the aforementioned surface modification layer includes, for example, corona treatment, plasma treatment, primer treatment, saponification treatment, and the like.

Examples of the easy-adhesive agent forming the aforementioned easy-adhesive layer include forming materials containing various resins having the following skeletons: polyester skeleton, polyether skeleton, polycarbonate skeleton, polyurethane skeleton, polysiloxane, poly Amide skeleton, polyimide skeleton, polyvinyl alcohol skeleton, etc. The aforementioned easy-adhesive layer is usually provided on the protective film in advance, and the easy-adhesive layer side of the protective film and the polarizing film are laminated by the aforementioned adhesive layer or the aforementioned adhesive layer.

The aforementioned barrier layer has a function of preventing impurities such as oligomers or ions eluted from the transparent protective film from moving (intruding) into the polarizing film. The aforementioned barrier layer may be a layer that has transparency and can prevent impurities eluted from a transparent protective film, etc. The material for forming the barrier layer includes, for example, a urethane prepolymer-based forming material and a cyanoacrylate-based forming material. , Epoxy-based forming materials, etc.

The refractive index adjustment layer is a layer provided in order to prevent the transmittance from being lowered due to reflection between layers having different refractive indexes such as the transparent protective film and the polarizing film. Examples of the refractive index adjusting material that forms the refractive index adjusting layer include forming agents containing various resins and additives such as silica-based, acrylic-based, acrylic-styrene-based, and melamine-based resins.

The polarizing film of the present invention satisfies the general formula (1): ΔTs _{(%) = Ts 750 -Ts 0} shows that the change in monomer transmittance (ΔTs) is 0% or more and 5% or less (the aforementioned general formula (1) In ), Ts ₀ is the monomer transmittance of the laminated body with the glass plate bonded to the adhesive layer on one side of the polarizing film, and Ts ₇₅₀ represents the monomer after the laminated body is heated at 95°C for 750 hours Transmittance). In addition, the amount of change (ΔTs) of the aforementioned monomer transmittance is preferably 0% or more and 3% or less, preferably 0% or more and 2% or less.

The degree of polarization of the aforementioned polarizing film is preferably 99.98% or more, and the degree of polarization is preferably 99.99% or more.

＜Layered Polarizing Film＞ The laminated polarizing film (optical laminate) of the present invention is obtained by bonding the aforementioned polarizing film to the optical layer. The aforementioned optical layer is not particularly limited. For example, one layer or two or more layers such as reflective plates and semi-transmissive plates, retardation plates (including 1/2 and 1/4 wavelength plates), viewing angle compensation films, etc. can be used to form liquid crystals. Optical layer for display devices, etc. As the laminated polarizing film, for example, a reflective polarizing film or a semi-transmissive polarizing film formed by laminating a reflective plate or a semi-transmissive reflective plate on the polarizing film, and a retardation plate is laminated on the polarizing film. Elliptically polarizing film or circular polarizing film, a wide viewing angle polarizing film formed by laminating a viewing angle compensation film on the polarizing film, or a polarizing film formed by laminating a brightness enhancement film on the polarizing film.

Adhesive layers can also be attached to one or both sides of the aforementioned polarizing film or the aforementioned multilayer polarizing film, which can be used to bond image display units such as liquid crystal cells or organic EL elements with transparent components such as front transparent plates or touch panels on the viewing side. And other components. The adhesive layer is preferably an adhesive layer. The adhesive forming the aforementioned adhesive layer is not particularly limited, and can be appropriately selected from acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based Such polymers are used as the base polymer. In particular, it can be suitably used, such as an acrylic polymer-containing adhesive, which has excellent optical transparency, exhibits moderate wettability, cohesiveness, and adhesiveness, and has excellent weather resistance or heat resistance.

Attaching the adhesive layer to one side or both sides of the aforementioned polarizing film or the aforementioned multilayer polarizing film can be carried out by an appropriate method. The adhesive layer can be attached by, for example, the following methods: preparing an adhesive solution, and directly attaching it to the aforementioned polarizing film or the aforementioned multilayer polarizing film by a suitable spreading method such as a casting method or a coating method; A method of forming an adhesive layer on the surface and transferring it to the aforementioned polarizing film or the aforementioned multilayer polarizing film. The thickness of the aforementioned adhesive layer can be appropriately determined according to the purpose of use or adhesion, etc., generally 1~500μm, preferably 5~200μm, more preferably 10~100μm. In this way, the polarizing film or the laminated polarizing film provided with an adhesive layer on at least one surface is called an adhesive layer-attached polarizing film or an adhesive layer-attached laminated polarizing film.

For the exposed surface of the aforementioned adhesive layer to prevent it from being contaminated, it is advisable to temporarily stick a separator to cover it before actual use. This can prevent the adhesive layer from being contaminated in the usual disposal state. As the aforementioned separating member, for example, suitable thin films such as plastic films, rubber sheets, paper, cloth, non-woven fabrics, nets, foam sheets or metal foils, and laminates of these can be used. Those who apply appropriate release agents such as alkyl group, fluorine or molybdenum sulfide, etc.

<Image display panel and image display device> The image display panel of the present invention is one in which the aforementioned polarizing film or the aforementioned laminated polarizing film is attached to the image display unit. In addition, the image display device of the present invention is provided with a front transparent member on the polarizing film or laminated polarizing film side (viewing side) of the aforementioned image display panel.

The aforementioned image display unit may be, for example, a liquid crystal cell or an organic EL unit. The aforementioned liquid crystal cell may use, for example, 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 external light and light from a light source. Either. When the aforementioned liquid crystal cell uses light from a light source, the image display device (liquid crystal display device) will also arrange a polarizing film on the side of the image display unit (liquid crystal cell) opposite to the viewing side, and will also arrange a light source. The polarizing film on the light source side and the liquid crystal cell should be attached through a suitable adhesive layer. The driving method of the aforementioned liquid crystal cell may use any type such as VA mode, IPS mode, TN mode, STN mode, or bend orientation (π-type).

The aforementioned organic EL unit can be suitably used, for example, a transparent electrode, an organic light-emitting layer, and a metal electrode are sequentially laminated on a transparent substrate to form a light-emitting body (organic electroluminescent body). The aforementioned organic light-emitting layer is a laminate of a variety of organic thin films. For example, the following various layers can be used: a laminate of a hole injection layer composed of triphenylamine derivatives and a light-emitting layer composed of a fluorescent organic solid such as anthracene; A laminate of the light-emitting layer and an electron injection layer composed of a perylene derivative, etc.; or a laminate of a hole injection layer, a light-emitting layer, and an electron injection layer, etc.

The front transparent member arranged on the viewing side of the aforementioned image display unit may, for example, be a front transparent plate (window layer) or a touch panel. For the aforementioned front transparent plate, a transparent plate with appropriate mechanical strength and thickness can be used. As the transparent plate, for example, a transparent resin plate such as an acrylic resin or a polycarbonate resin, a glass plate, or the like can be used. As the aforementioned touch panel, various touch panels such as resistive film type, capacitive type, optical type, ultrasonic type, etc., or glass plate or transparent resin plate with touch sensing function can be used. When a capacitive touch panel is used as the aforementioned transparent plate, it is advisable to provide a glass or a transparent resin plate on the front surface of the transparent plate on the side closer to the visibility than the touch panel.

The polarizing film of the present invention has the following polarizing film. Therefore, the polarizing film of the present invention, and the laminated polarizing film, image display panel, and image display device using the polarizing film are suitable for use in car navigation devices or rear-illuminated monitors and other vehicle-mounted image display devices Purpose: The polarizing film of the present invention has a good initial polarization degree and a good effect of inhibiting the reduction of the monomer transmittance caused by the coloring of the polarizing film in a high temperature environment, and a good effect of inhibiting the decrease of the polarization degree under a high temperature and high humidity environment.

Example Examples are listed below to illustrate the present invention in more detail, but the present invention is not limited to these examples.

…(9)<Example 1><Preparation of a polarizing film> The thermoplastic resin substrate used a long strip of amorphous isophthalic acid copolymer polyethylene terephthalate film with a water absorption rate of 0.75% and a Tg of about 75°C (thickness: 100μm). And applied corona treatment to one side of the resin substrate. In a 9:1 mixture of polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetyl acetyl modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER Z410"). To 100 parts by weight of resin, 13 parts by weight of potassium iodide was added to prepare a PVA aqueous solution (coating liquid). The above-mentioned PVA aqueous solution was applied to the corona-treated surface of the resin substrate and dried at 60° C. to form a PVA-based resin layer with a thickness of 13 μm to produce a laminate. The obtained laminate was uniaxially stretched 2.4 times in the longitudinal direction (long side direction) between rollers with different peripheral speeds in an oven at 130°C (air-assisted stretching treatment). Next, the layered body was immersed in an insoluble bath (an aqueous solution with a boric acid concentration of 4.0% by weight) at a liquid temperature of 40°C for 30 seconds (insoluble treatment). Next, adjust the concentration in a dyeing bath (100 parts by weight of water and an iodine aqueous solution obtained by mixing iodine and potassium iodide at a weight ratio of 1:7) at a liquid temperature of 30°C and immerse it for 60 seconds to make the final The iodine concentration of the polarizing film obtained was 9.3% (dyeing treatment). Then, it was immersed in a crosslinking bath (aqueous solution with a potassium iodide concentration of 3.0% by weight and a boric acid concentration of 5.0% by weight) at a liquid temperature of 40°C for 30 seconds (crosslinking treatment). Then, while immersing the layered body in a boric acid aqueous solution (boric acid concentration 4.0% by weight) at a liquid temperature of 70°C, uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds so that the total stretch magnification reached 5.5 times (extension treatment in water). Next, the laminate was immersed in a washing bath with a liquid temperature of 20°C (a potassium iodide concentration of 3% by weight, and a compound with a radical trapping function, represented by the following general formula (9), in an aqueous solution with a concentration of 1.0% by weight) ( Washing treatment). After that, while drying in an oven maintained at 90°C, the contact surface temperature was maintained at 75°C with a heating roll made of SUS for about 2 seconds (drying shrinkage treatment). Through the above procedures, a polarizing film with a thickness of 5 μm was formed on the resin substrate. In addition, the dehydration temperature of polyolefination of the obtained polarizing film (the peak temperature of the maximum intensity of water detected by the outgas analysis method) was 204°C, and the content of the compound represented by the following general formula (9) in the polarizing film It is 0.3% by weight. [Chemical formula 9]

…(9)

[Measurement method of iodine concentration (wt%) in polarizing film] For the polarizing film, an X-ray fluorescence analyzer (manufactured by Rigaku, trade name "ZSX-PRIMUS IV", measurement diameter: ψ20 mm) was used, and the iodine concentration (% by weight) was determined by the following formula. Iodine concentration (wt%=14.474×(X-ray fluorescence intensity)/(film thickness)(kcps/μm)) In addition, the coefficient when calculating the concentration will be different depending on the measuring device, but the coefficient can use an appropriate amount The curve is obtained.

[Determination method of dehydration temperature for polyolefination] The polarizing film is introduced into a furnace-type pyrolyzer (Frontier Laboratories, PY-2020iD), and then the generated gas is directly introduced into TOFMS (JEOL, MS-T100GCV), using outgas analysis (EGA/TOFMS) Method to determine the peak temperature of the maximum intensity of the detected water, and use this temperature as the dehydration temperature for polyolefination. [Measurement conditions] Heating conditions: 40℃→＋10℃/min→350℃ Interface: Inactive fused silica tube, 2.5m×0.15mm id Carrier gas: He(1.0mL/min) Note inlet temperature: 300℃ Note inlet: split ratio 20:1 Interface temperature: 300℃ Quality Analyzer: TOFMS Ionization method: EI method Mass range: m/z=18

[Method for measuring the content (wt%) of the compound with free radical trapping function in the polarizing film] About 20 mg of the polarizing film was taken and quantified. After heating and dissolving in 1 mL of water, it was diluted with 4.5 mL of methanol, and the obtained extract was filtered with a membrane filter, and the filtrate was measured by HPLC (ACQUITY UPLC H-class Bio manufactured by Waters) Concentration of compounds with free radical capture function.

<Preparation of polarizing film> The following aqueous solution is used as the adhesive: a weight ratio of 3:1 containing polyvinyl alcohol resin containing acetyl group (average degree of polymerization 1,200, degree of saponification 98.5 mol%, degree of acetylation degree 5 mol%) and methylol melamine. Using this adhesive, a transparent protective film (made by Nippon Shokubai) with a thickness of 30μm composed of (meth)acrylic resin (modified acrylic polymer with a lactone ring structure) (made by Nippon Shokubai) with a moisture permeability of 125g/ (m ² ·24h)) As the first transparent protective film, it was bonded to the surface (image display unit side) of the polarizing film obtained above on the opposite side to the resin substrate. Next, the resin substrate is peeled off, and a transparent protective film (transparent) with a thickness of 47μm with HC is formed on a triacetate cellulose film (manufactured by Fuji Film, trade name "TJ40UL") with a roll laminator through an ultraviolet curable adhesive. Humidity is 380g/(m ²・24h)) as the second transparent protective film, attached to the peeled surface (view side), and then irradiated with UV light from the transparent protective film surface to harden the adhesive to produce a polarizing film .

[Method for measuring monomer transmittance under high temperature environment] The polarizing film obtained above was cut into a size of 5.0×4.5 cm so that the absorption axis of the polarizing film was parallel to the long side, and passed through an acrylic with a thickness of 20 μm Adhesive layer The glass plate (analog image display unit) is attached to the protective film surface of the polarizing film on the side of the image display unit, and then autoclaved at 50°C and 0.5MPa for 15 minutes to produce a laminate. The resulting laminate was left in a hot air oven at a temperature of 95°C for 750 hours, and the monomer transmittance (ΔTs) before and after the input (heating) was measured. The monomer transmittance was measured using a spectrophotometer (manufactured by JASCO Corporation, product name "V7100"), and evaluated based on the following criteria. In addition, the measurement wavelength is 380 to 700 nm (every 5 nm). The results are listed in Table 1. ΔTs (%)=Ts _{750 −Ts 0} Here, Ts ₀ is the monomer transmittance of the laminate before heating, and Ts ₇₅₀ is the monomer transmittance of the laminate after heating for 750 hours.

[Assess the degree of polarization] The degree of polarization of the polarizing film can be measured using a spectrophotometer (manufactured by JASCO, product name "V7100"). The specific measurement method of polarization degree is to measure the parallel transmittance (H0) and orthogonal transmittance (H90) of the polarizing film, which can be determined by the formula: polarization degree (%)={(H0-H90)/(H0+H90)}1 /2×100 to find. The parallel transmittance (H0) is the value of the transmittance of the parallel-type laminated polarizing film, which is made by stacking two identical polarizing films so that the absorption axes of both sides are parallel. In addition, the cross transmittance (H90) is the value of the transmittance of the cross-type laminated polarizing film, which is made by stacking two identical polarizing films so that the absorption axes of both sides are orthogonal to each other. In addition, the transmittance is the Y value obtained by the visual sensitivity correction of the 2 degree field of view (C light source) of JIS Z 8701-1982. The results are listed in Table 1.

[Evaluation of humidification durability] After placing the laminate sample in a humid oven at 85°C and 85% RH for 240 hours, the degree of polarization was evaluated by the spectrophotometer (Japan Seiko Co., Ltd., product name "V7100"). The results are listed in Table 1. ○: Polarization degree above 90% ×: The degree of polarization is less than 90%

[Evaluation panel warpage] Cut into a size of 145×105mm with the absorption axis of the polarizing film parallel to the long side, and stick a thickness of 0.4mm on the protective film surface of the polarizing film on the image display unit side of the polarizing film through an acrylic adhesive layer with a thickness of 20μm. And the size of the glass plate of 155×115mm. The obtained glass (analog panel) sample with polarizing film was placed in a hot air oven at 85°C for 5 hours, and then placed in a room temperature and humidity environment for 1 hour, and then the amount of warpage of the glass was evaluated. Warpage refers to the amount of curvature of the glass and polarizer that is convex to the lower side. The results are listed in Table 1. ○: The amount of warpage is less than 1.0mm ×: The amount of warpage is 1.0mm or more

<Example 2> <Production of polarizing film and polarizing film> When producing the polarizing film, the iodine concentration of the dye bath was adjusted so that the iodine concentration of the finally obtained polarizing film became 6.3% by weight, except that the same operation as in Example 1 was performed to prepare the polarizing film and the polarizing film. The peak temperature of the maximum intensity of water detected by the outgas analysis method of the obtained polarizing film was 207°C, the content of the compound represented by the general formula (9) in the polarizing film was 0.3% by weight, and the thickness of the polarizing film was 5 μm.

<Example 3> <Production of polarizing film and polarizing film> Prepare a polyvinyl alcohol film with an average degree of polymerization of 2,400, a degree of saponification of 99.9 mol%, and a thickness of 30 μm. While immersing the polyvinyl alcohol film in a swelling bath (water bath) at 20°C for 30 seconds between rolls with different peripheral speed ratios for swelling, it stretched 2.2 times in the conveying direction (swelling step), and then heated at 30°C. Adjust the concentration in a dyeing bath (an iodine aqueous solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with respect to 100 parts by weight of water) and immerse for 30 seconds for dyeing, so that the final iodine concentration of the polarized film obtained becomes 6.1 weight %, and stretched 3.3 times in the conveying direction based on the original polyvinyl alcohol film (a polyvinyl alcohol film that has not been stretched in the conveying direction at all) (dyeing step). Next, the dyed polyvinyl alcohol film was immersed in a cross-linking bath (an aqueous solution with a boric acid concentration of 3.5% by weight, potassium iodide concentration of 3.0% by weight, and zinc sulfate concentration of 3.6% by weight) at 40°C for 28 seconds, and the original Based on the polyvinyl alcohol film, stretched to 3.6 times in the conveying direction (crosslinking step). Then the obtained polyvinyl alcohol film was immersed in a stretching bath (an aqueous solution with 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) at 64°C for 60 seconds, and the original polyvinyl alcohol After the film is stretched to 6.0 times in the conveying direction (stretching step) based on the basis, it is shown in the following general formula (6) as a compound with a free radical trapping function in a 27°C washing bath (potassium iodide concentration is 2.3% by weight) The compound is immersed in an aqueous solution with a compound concentration of 1.0% by weight for 10 seconds (washing step). The washed polyvinyl alcohol film was dried at 40°C for 30 seconds to prepare a polarizing film. The peak temperature of the maximum intensity of water detected by the outgas analysis method of the obtained polarizing film was 209°C, the content of the compound represented by the general formula (9) in the polarizing film was 0.2% by weight, and the thickness of the polarizing film was 12 μm.

Next, the following aqueous solution was used for the adhesive: a weight ratio of 3:1 containing polyvinyl alcohol resin containing acetyl acetyl groups (average degree of polymerization 1,200, saponification degree 98.5 mol%, acetyl acetylation degree 5 mol) %) Those with methylol melamine. Using this adhesive, a cellulose triacetate film (manufactured by Fujifilm, trade name "TJ40UL") was laminated on one side (viewing side) of the polarizing film obtained above with a roll laminator to form a transparent protection of 47μm in thickness with HC The film (with a moisture permeability of 380g/(m ² · 24h)) is used as the second transparent protective film, and on the other side (the side of the image display unit) is laminated a (meth)acrylic resin (with a lactone ring structure). A transparent protective film with a thickness of 30μm (made by Nippon Shokubai, with a moisture permeability of 125g/(m ² · 24h)) composed of acrylic polymer) is used as the first transparent protective film, and then it is heated and dried in an oven (temperature The temperature is 90°C and the time is 10 minutes), and a polarizing film with a transparent protective film attached to both sides of the polarizing film is produced.

<Example 4> <Production of polarizing film and polarizing film> When making a polarizing film, add 1.0% by weight of the compound represented by the above general formula (8) to the washing bath instead of the above general formula (9), except that the same operation method as in Example 1 was used to prepare a polarizing film And polarizing film. The peak temperature of the maximum intensity of water detected by the outgas analysis method of the obtained polarizing film was 205°C, the content of the compound represented by the general formula (8) in the polarizing film was 0.3% by weight, and the thickness of the polarizing film was 5 μm.

…(10)<Example 5><Preparation of polarizing film and polarizing film> When making a polarizing film, the iodine concentration of the dyeing bath was adjusted so that the iodine concentration of the polarizing film finally obtained became 9.2% by weight, and the iodine concentration was adjusted to potassium iodide in the washing bath The concentration was 1.8% by weight, the compound represented by the following general formula (10) in place of the above general formula (9) was 1.0% by weight, and the sodium chloride was 15% by weight, except that the same operation method as in Example 1 was used. Produce polarizing film and polarizing film. The peak temperature of the maximum intensity of water detected by the outgas analysis method of the obtained polarizing film is 205°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 chloride ion is 2.7 Weight %, the thickness of the polarizing film is 5μm. In addition, the chloride ion system was obtained by the following measurement method. [Chemical formula 10]

…(10)

[Measurement method of chloride ion (chloride ion)] Take 5 mg of the sample into a polyene propylene container, add 20 mL of ultrapure water, and close the lid. Next, after heating and extracting at 120° C. for 1 hour, the obtained extract was filtered with a membrane filter and an organic substance removal cartridge, and quantitatively analyzed by an ion chromatograph to calculate chloride ions. [Measurement conditions] Device (anion): ICS-3000 manufactured by Thermo Fisher Scientific Separation column: Dionex IonPac AS18-fast (4mm×150mm) Protection column: Dionex IonPac AG18-fast(4mm×30mm) Removal system: Dionex AERS-500 (external mode) Detector: conductivity detector Eluent: KOH aqueous solution (using the eluent generator EGCIII) Eluent flow rate: 1.2mL/min Sample injection volume: 250μL

<Example 6> <Production of polarizing film and polarizing film> In the production of the polarizing film, the compound represented by the above general formula (10) was not added, except that the polarizing film and the polarizing film were prepared by the same operation method as in Example 5. The peak temperature of the maximum intensity of water detected by the outgas analysis method of the obtained polarizing film was 205°C, the chloride ion content in the polarizing film was 2.9% by weight, and the thickness of the polarizing film was 5 μm.

<Comparative example 1> <Production of polarizing film and polarizing film> When making the polarizing film, the iodine concentration of the dyeing bath is adjusted so that the iodine concentration of the polarizing film finally obtained becomes 8.5% by weight, and the compound represented by the general formula (9) is not added to the washing bath as a free radical trap The functional compound, except that the polarizing film and the polarizing film were prepared by the same operation as in Example 1. The peak temperature of the maximum intensity of water detected by the outgas analysis method of the obtained polarizing film was 193°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 5 μm.

＜Comparative example 2＞ <Production of polarizing film and polarizing film> When making the polarizing film, the iodine concentration of the dyeing bath is adjusted so that the iodine concentration of the polarizing film finally obtained becomes 5.6% by weight, and the compound represented by the above general formula (9) is not added to the washing bath as a free radical trap The functional compound, except that the polarizing film and the polarizing film were prepared by the same operation as in Example 1. The peak temperature of the maximum intensity of water detected by the outgas analysis method of the obtained polarizing film was 203°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 5 μm.

<Comparative example 3><Preparation of polarizing film and polarizing film> Except for the first transparent protective film, a tri-cellulose acetate film (manufactured by Konica Minolta, trade name "KC2CT" ^{with a thickness of 20 μm and a moisture permeability of 1270 g/(m 2 · 24h)) was used} ), using the same method as in Example 2 to produce a polarizing film.

Using the polarizing films of the respective Examples and Comparative Examples obtained above, the above-mentioned [Method for Measuring Monomer Transmittance in High-Temperature Environment], [Evaluation of Polarization Degree], [Evaluation of Humidification Durability], and [Evaluation of Panel Warpage ]. The results are listed in Table 1.

[Table 1]

(no)

Claims (11)

A polarizing film, which is laminated with a transparent protective film on both sides of the polarizing film; the characteristic of the polarizing film is that: the polarizing film is formed by adsorbing and oriented iodine on the polyvinyl alcohol film, and the iodine concentration is more than 6 wt%; The moisture permeability of at least one of the aforementioned transparent protective films is 200g/(m ² ·24h) or less; the aforementioned polarizing film satisfies the following general formula (1). The monomer transmittance change (ΔTs) is 0% or more and Under the condition of 5%, the general formula (1): ΔTs _{(%)=Ts 750 -Ts 0} (in the general formula (1), Ts ₀ is a glass plate attached to one side of the polarizing film through the adhesive layer The monomer transmittance of the laminate, Ts ₇₅₀ represents the monomer transmittance of the laminate after heat treatment at 95°C for 750 hours). The polarizing film of claim 1, wherein the thickness of the aforementioned polarizing film is 15 μm or less. The polarizing film of claim 1 or 2, wherein the aforementioned polarizing film contains a compound having a radical trapping function. The polarizing film of claim 3, wherein the aforementioned compound having a radical trapping function is a compound having nitroxide radicals or nitroxyl radicals. The polarizing film of claim 1 or 2, wherein the aforementioned polarizing film contains chloride ions. The polarizing film of claim 5, wherein the content of the chloride ion in the polarizing film is 0.1% by weight or more. For example, the polarizing film of claim 1 or 2 has a degree of polarization of 99.98% or more. A laminated polarizing film, characterized in that it is bonded to an optical layer as the polarizing film of any one of claims 1 to 7. An image display panel, characterized in that it is laminated with the polarizing film of any one of claims 1 to 7 or the laminated polarizing film of claim 8 on the image display unit. An image display device, characterized in that it is provided with a front transparent member on the side of the polarizing film or laminated polarizing film of the image display panel of claim 9. Such as the image display device of claim 10, which is used for in-vehicle use.