CN115698789A

CN115698789A - Polarizing film, optical film, and image display device

Info

Publication number: CN115698789A
Application number: CN202180040743.XA
Authority: CN
Inventors: 菅野亮; 洼添日名子
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2020-07-13
Filing date: 2021-03-25
Publication date: 2023-02-03
Also published as: JP7179802B2; JP2022017074A; KR20230035224A; TW202202881A; WO2022014102A1

Abstract

The present invention provides a polarizing film, which comprises: and an adhesive layer adjacent to the polarizer or an optical film other than the polarizer, wherein the polarizing film has no bright spot derived from a foreign substance more than 3mm from the end face after being exposed to a humidity durability test for 1000 hours in an environment of 65 to 95% humidity. The polarizer preferably contains a metal component capable of becoming a divalent metal cation in water, particularly zinc.

Description

Polarizing film, optical film, and image display device

Technical Field

The present invention relates to a polarizing film including a polarizer and an adhesive layer adjacent to the polarizer or an optical film other than the polarizer. The polarizing film may be used alone or in the form of an optical film in which the polarizing film is laminated to form an image display device such as a mobile phone, a car navigation device, a computer monitor, or a television.

Background

Liquid crystal display devices are rapidly becoming on the market in mobile phones, car navigation devices, monitors for computers, televisions, and the like. A liquid crystal display device is a device for visualizing the polarization state of a liquid crystal switch, and uses a polarizer based on the display principle. In particular, in applications such as TVs, high brightness, high contrast, and wide viewing angles are increasingly required, and polarizing films are also increasingly required to have high transmittance, high polarization, high color reproducibility, and the like.

As the polarizer, an iodine polarizer having a structure in which iodine is adsorbed to polyvinyl alcohol (hereinafter, also referred to as "PVA") and stretched is generally most widely used from the viewpoint of having high transmittance and high degree of polarization. Generally, a polarizing film is used in which a transparent protective film is laminated on both surfaces of a polarizer by using a so-called aqueous adhesive in which a polyvinyl alcohol-based material is dissolved in water (patent document 1). As the transparent protective film, cellulose triacetate having high moisture permeability or the like is used. When the aqueous adhesive is used (so-called wet lamination), a drying step is required after the polarizer and the transparent protective film are bonded.

On the other hand, an active energy ray-curable adhesive has been proposed instead of the aqueous adhesive. When the polarizing film is produced using the active energy ray-curable adhesive, the productivity of the polarizing film can be improved because a drying step is not required. For example, a radical polymerization type active energy ray-curable adhesive using an N-substituted amide monomer as a curable component has been proposed (patent document 2). The adhesive layer formed using the active energy ray-curable adhesive described in patent document 2 can sufficiently withstand, for example, a water resistance test for evaluating the presence or absence of discoloration or peeling after immersion in hot water at 60 ℃ for 6 hours. However, in recent years, polarizing films are often used not only for portable devices such as mobile phones but also for image display devices for in-vehicle applications, and in-vehicle applications, it is necessary to satisfy durability tests under higher temperature and humidity conditions than in portable devices.

Documents of the prior art

Patent literature

Patent document 1: japanese patent laid-open No. 2001-296427

Patent document 2: japanese laid-open patent publication No. 2012-052000

Disclosure of Invention

Problems to be solved by the invention

As a durability test required for a polarizing film used for an in-vehicle application, there is, for example, a humidification durability test in which the polarizing film is exposed to an environment of 65 to 95% humidity for 1000 hours. Here, the present inventors have studied in detail the appearance state of the polarizing film after the humidification durability test, and found that, in particular, bright spots from foreign matter, which are white misty, are generated at the ends of the polarizing film, and the bright spots become product defects in terms of appearance characteristics. Such a phenomenon is first observed after a durability test in a high-temperature and high-humidity environment, and intensive studies have been necessary to solve this new problem.

The present invention has been made in view of the above circumstances, and an object thereof is to provide a polarizing film which suppresses the occurrence of bright spots from foreign matter even after a humidification durability test and has excellent appearance characteristics.

Means for solving the problems

The above problem can be solved by the following configuration. That is, the present invention relates to a polarizing film comprising a polarizer and an adhesive layer adjacent to the polarizer or an optical film other than the polarizer, wherein the polarizing film does not have a bright spot derived from a foreign substance more than 3mm from an end surface after being exposed to a humidity durability test for 1000 hours in an environment of 65 to 95% humidity.

In the polarizing film, the polarizer preferably contains a metal component capable of forming a divalent metal cation in water.

In the polarizing film, the metal component is preferably zinc.

In the polarizing film, it is preferable that the polarizing film includes:

a polarizer,

An optical film laminated on at least one surface of the polarizer via an aqueous adhesive layer, and

and an adhesive layer provided on a surface of the optical film opposite to the aqueous adhesive layer.

In the polarizing film, the adhesive layer is preferably formed of a cured product layer of an active energy ray-curable adhesive composition.

In the polarizing film, the adhesive layer is preferably formed of a cured product layer of an adhesive composition, and when a cured product obtained by curing the adhesive composition is immersed in pure water at 23 ℃ for 24 hours, the bulk water absorption rate represented by the following formula is less than 10% by weight,

formula (II): { (M2-M1)/M1 }. Times.100 (%)

Wherein, M1: weight of cured product before immersion, M2: weight of cured product after immersion.

In the polarizing film, it is preferable that the (number of carbon atoms)/(number of oxygen atoms + number of nitrogen atoms) measured based on the element ratio of the adhesive layer is 2.5 or more.

In the polarizing film, the adhesive layer is preferably formed of a cured product layer of an adhesive composition, and logPow representing an octanol/water partition coefficient based on a weighted average of mole fractions of monomer components contained in the adhesive composition is preferably 1.6 or more.

In the polarizing film, the adhesive composition preferably contains 25 parts by weight or more of a monomer component having an alkyl group having 8 or more carbon atoms, based on 100 parts by weight of the total monomer components.

In the polarizing film, the adhesive composition preferably contains 40 parts by weight or less of a monomer component having a hydroxyl group, based on 100 parts by weight of the total amount of the monomer components.

The present invention also relates to an optical film in which at least 1 sheet of the polarizing film described in any one of the above is laminated, and an image display device using the polarizing film described in any one of the above and/or the optical film described above.

ADVANTAGEOUS EFFECTS OF INVENTION

Polarizing films used for in-vehicle applications and the like are required to have excellent appearance characteristics even after exposure to a humidity durability test for 1000 hours in an environment of 65 to 95% humidity, for example. The polarizing film of the present invention has excellent appearance characteristics because it has no bright spots derived from foreign matter more than 3mm from the end face after the humidification durability test.

In particular, the polarizing film of the present invention has excellent appearance characteristics even when it contains a polarizer containing a metal component capable of forming a divalent metal cation in water, in particular, zinc. The reason why this effect can be obtained is not clear, but the following reason can be presumed, for example.

In a polarizing film including a polarizer and an adhesive layer adjacent to the polarizer or an optical film other than the polarizer, a metal component capable of forming a divalent metal cation in water, particularly zinc, contained in the polarizer moves into the adhesive layer through steam and dew condensation at an end of the polarizing film in a humidification durability test. Here, in the adhesive layer, components other than the components contained in the adhesive composition serving as the raw material, for example, oxalic acid, are present in an ionized state, but oxalic acid is not detected as foreign matter in the adhesive layer unless it forms oxalate by bonding with the metal component. However, in the humidification durability test, if a specific metal component contained in the polarizer is mixed into the adhesive layer from the end portion, the ionized oxalic acid is bonded to the metal component, and particularly, oxalate is generated at the end portion in the adhesive layer, which becomes a white bright point and is detected as a foreign substance. As a result, the appearance characteristics of the polarizing film are deteriorated.

The polarizing film of the present invention comprises: and an adhesive layer adjacent to the polarizer or an optical film other than the polarizer, wherein the polarizing film has no bright spot derived from a foreign substance more than 3mm from the end face after being exposed to a humidity durability test for 1000 hours in an environment of 65 to 95% humidity. In particular, in the case where the polarizer of the present invention includes an adhesive layer designed such that the bulk water absorption of the cured product layer of the adhesive composition as a raw material is less than 10 wt%, even when a specific metal component contained in the polarizer is mixed into the adhesive layer from the end, the bonding of the ionized oxalic acid to the metal component and the movement of the oxalate from the end of the polarizing film to the inside are suppressed. As a result, the appearance characteristics of the polarizing film were particularly improved even after the humidification durability test.

In particular. The adhesive layer provided in the polarizing film of the present invention is formed of a cured layer of an adhesive composition, and (i) when (carbon number)/(oxygen number + nitrogen number) measured based on the element ratio of the adhesive layer is 2.5 or more, or (ii) logPow representing the octanol/water distribution coefficient based on the weighted average of the mole fractions of the monomer components contained in the adhesive composition is 1.6 or more, the bonding of oxalic acid after ionization to the metal component and the movement of oxalate from the end portion to the inside of the polarizing film can be suppressed at the end portion in particular in the adhesive layer. As a result, the appearance characteristics of the polarizing film were significantly improved even after the humidification durability test.

Drawings

Fig. 1 is an example of a schematic cross-sectional view of a polarizing film according to an embodiment of the present invention.

Fig. 2 is another example of a schematic cross-sectional view of a polarizing film according to an embodiment of the present invention.

Description of the symbols

10. Polarizing film

1. Polarizer

2. Aqueous adhesive

3. 4,6 optical film

5. Adhesive layer

7. Adhesive layer

Detailed Description

Fig. 1 shows an example of a schematic cross-sectional view of a polarizing film according to an embodiment of the present invention. The polarizing film 10 in this embodiment includes: a polarizer 1, and an adhesive layer 5 adjacent to the 1 st optical film 4 other than the polarizer 1. More specifically, the polarizing film 10 includes: a polarizer 1, a1 st optical film (retardation film) 4 laminated on at least one surface of the polarizer 1 via an aqueous adhesive layer 2, and an adhesive layer 5 provided on one surface of the 1 st optical film (retardation film) 4 opposite to the aqueous adhesive layer 2. In particular, the polarizing film 10 of this embodiment is formed by laminating a 2 nd optical film (transparent protective film) 3 on one surface of a polarizer 1 via an aqueous adhesive layer 2, a1 st optical film (retardation film) 4 on the other surface of the polarizer 1 via the aqueous adhesive layer 2, an adhesive layer 5 on the 1 st optical film (retardation film) 4, and a 3 rd optical film (retardation film) 6 on the adhesive layer 5. The polarizing film 10 is further laminated with an adhesive layer 7 on the 3 rd optical film 6, and is laminated on an image display unit or the like via the adhesive layer 7.

Fig. 2 shows another example of a schematic cross-sectional view of a polarizing film according to an embodiment of the present invention. The polarizing film 10 in this embodiment includes: a polarizer 1, and an adhesive layer 5 adjacent to the polarizer 1. More specifically, in the polarizing film 10 of this embodiment, a 2 nd optical film (transparent protective film) 3 is laminated on one surface of the polarizer 1 via an aqueous adhesive layer 2, and a1 st optical film (retardation film) 4 is laminated on the other surface of the polarizer 1 via an adhesive layer 5. The polarizing film 10 is further laminated with an adhesive layer 7 on the optical film 4, and is laminated on an image display unit or the like via the adhesive layer 7.

In the polarizing film shown in fig. 1 and 2, an aqueous solution (for example, a solid content concentration of 0.5 to 60% by weight) of an aqueous adhesive such as an isocyanate adhesive, a polyvinyl alcohol adhesive, a gelatin adhesive, a vinyl latex, or an aqueous polyester is suitably used as the aqueous adhesive layer 2. The thickness of the aqueous adhesive layer 2 is not particularly limited, and is usually about 0.01 μm to 0.5 μm in thickness after drying.

In the polarizing film 10 shown in fig. 1 and 2, a metal component capable of forming a divalent metal cation in water, particularly zinc, contained in the polarizer 1 moves into the adhesive layer 5 through vapor and dew condensation at the end of the polarizing film 10 in a humidification durability test. Here, in the adhesive layer 5, components other than the components contained in the adhesive composition serving as the raw material, for example, oxalic acid, are present in an ionized state, but oxalic acid is not detected as foreign matter in the adhesive layer unless it forms oxalate by bonding with the metal component. Here, if a specific metal component contained in the polarizer 10 is mixed into the adhesive layer 5 in the humidification durability test, the ionized oxalic acid is bonded to the metal component to generate oxalate and become a white bright point, and the white bright point is detected as foreign matter, but after the polarizing film 10 shown in fig. 1 and 2 is exposed to the humidity environment of 65 ℃ to 95% for 1000 hours in the humidification durability test, the bright point from the foreign matter is not present more than 3mm from the end face, more preferably more than 2mm from the end face.

Hereinafter, each configuration of the polarizing film of the present invention will be described. In the present invention, a polarizing film includes: a polarizer, and an adhesive layer adjacent to the polarizer or an optical film other than the polarizer.

< polarizer >

As a material of the polyvinyl alcohol based film suitable for the polarizer, polyvinyl alcohol or a derivative thereof is used. Examples of the derivative of polyvinyl alcohol include polyvinyl formal, polyvinyl acetal, and the like, and further, a derivative of polyvinyl alcohol modified with an olefin such as ethylene or propylene, an unsaturated carboxylic acid such as acrylic acid, methacrylic acid, crotonic acid, an alkyl ester thereof, acrylamide, and the like. Polyvinyl alcohol is generally used which has a polymerization degree of about 1000 to 10000 and a saponification degree of about 80 to 100 mol%.

The polyvinyl alcohol film may contain an additive such as a plasticizer. Examples of the plasticizer include polyhydric alcohols and condensates thereof, and examples thereof include: glycerin, diglycerin, triglycerol, ethylene glycol, propylene glycol, polyethylene glycol, and the like. The amount of the plasticizer to be used is not particularly limited, and is preferably 20% by weight or less in the polyvinyl alcohol film.

In the production of the polarizer, a dyeing step of dyeing the polyvinyl alcohol film with iodine and a stretching step of stretching the polyvinyl alcohol film in at least one direction are performed. In general, the polyvinyl alcohol film may be subjected to a series of steps including swelling, dyeing, crosslinking, stretching, washing with water, and drying.

The swelling step can be performed, for example, by immersing the polyvinyl alcohol-based film in a swelling bath (water bath). By this treatment, the polyvinyl alcohol based film can be swollen while cleaning the dirt and the antiblocking agent on the surface of the polyvinyl alcohol based film, and unevenness such as uneven dyeing can be prevented. Glycerin, potassium iodide, and the like may be added to the swelling bath as appropriate. The temperature of the swelling bath is usually about 20 to 60 ℃ and the immersion time in the swelling bath is usually about 0.1 to 10 minutes.

The dyeing step can be performed by, for example, immersing the polyvinyl alcohol film in an iodine solution. The iodine solution is usually an aqueous iodine solution containing iodine and potassium iodide as a dissolution aid. The iodine concentration is usually about 0.01 to 1% by weight, preferably 0.02 to 0.5% by weight. The potassium iodide concentration is usually about 0.01 to 10% by weight, preferably 0.02 to 8% by weight.

In the iodine dyeing step, the temperature of the iodine solution is usually about 20 to 50 ℃, preferably 25 to 40 ℃. The immersion time is usually about 10 to 300 seconds, preferably 20 to 240 seconds. In the iodine dyeing treatment, it is preferable to adjust conditions such as the concentration of the iodine solution, the immersion temperature of the polyvinyl alcohol film in the iodine solution, and the immersion time so that the iodine content and the potassium content in the polyvinyl alcohol film fall within the above ranges.

The crosslinking step can be performed, for example, by immersing the iodine-dyed polyvinyl alcohol film in a treatment bath containing a crosslinking agent. As the crosslinking agent, any suitable crosslinking agent can be used. Specific examples of the crosslinking agent include boron compounds such as boric acid and borax, glyoxal, and glutaraldehyde. These crosslinking agents may be used alone or in combination. The solvent used in the solution of the crosslinking bath is usually water, but an organic solvent compatible with water may be added as appropriate. The crosslinking agent is usually used in a proportion of 1 to 10 parts by weight relative to 100 parts by weight of the solvent. Preferably, the solution of the crosslinking bath further contains an auxiliary such as iodide. The concentration of the auxiliary is preferably 0.05 to 15% by weight, and more preferably 0.5 to 8% by weight. The temperature of the crosslinking bath is usually about 20 to 70 ℃ and preferably 40 to 60 ℃. The immersion time in the crosslinking bath is usually about 1 second to 15 minutes, preferably about 5 seconds to 10 minutes.

The stretching step is a step of stretching the polyvinyl alcohol-based film in at least one direction. In general, a polyvinyl alcohol-based film is uniaxially stretched in the transport direction (longitudinal direction). The stretching method is not particularly limited, and any of a wet stretching method and a dry stretching method may be employed. In the case of the wet stretching method, the polyvinyl alcohol-based film is stretched to a given magnification in a treatment bath. As the solution of the stretching bath, a solution obtained by adding a compound necessary for various treatments to a solvent such as water or an organic solvent (e.g., ethanol) can be suitably used. Examples of the dry stretching method include an inter-roll stretching method, a heated roll stretching method, and a compression stretching method. In the production of the polarizer, the drawing step may be performed at any stage. Specifically, the swelling, dyeing and crosslinking may be performed simultaneously, or may be performed at any time before or after the above-described steps. In addition, the stretching may be performed in a plurality of stages. The cumulative draw ratio of the polyvinyl alcohol film is usually 5 times or more, preferably about 5 to 7 times.

In the present invention, the polarizer preferably contains a metal component capable of becoming a divalent metal cation in water, more preferably contains magnesium, calcium, copper or zinc, and particularly preferably contains zinc. By including zinc in the polarizer, the decrease in transmittance and the deterioration in hue of the polarizing film after the heat test tend to be suppressed. When the polarizer contains zinc, the content of zinc in the polarizer is preferably 0.002 to 2% by weight, more preferably 0.01 to 1% by weight.

In the present invention, the polarizer preferably contains a sulfate ion. When the polarizer contains a sulfate ion, the decrease in transmittance of the polarizing film after the heat test tends to be suppressed. When the polarizer contains sulfate ions, the content of the sulfate ions in the polarizer is preferably 0.02 to 0.45% by weight, more preferably 0.05 to 0.35% by weight, and still more preferably 0.1 to 0.25% by weight. The content of sulfate ions in the polarizer can be calculated from the sulfur atom content.

In order to incorporate zinc into the polarizer, it is preferable to perform zinc impregnation treatment in the polarizer manufacturing process. In order to contain sulfate ions in the polarizer, it is preferable to perform a sulfate ion treatment in the polarizer manufacturing process.

The zinc impregnation treatment can be performed by, for example, immersing the polyvinyl alcohol film in a zinc salt solution. As the zinc salt, inorganic chlorine compounds such as zinc halides such as zinc chloride and zinc iodide, and aqueous solutions of zinc sulfate and zinc acetate are preferable. In the zinc impregnation treatment, various zinc complexes may be used. In addition, when an aqueous solution containing potassium ions and iodide ions by using potassium iodide or the like is used as the zinc salt solution, zinc ions are easily impregnated, which is preferable. The concentration of potassium iodide in the zinc salt solution is preferably about 0.5 to 10% by weight, and more preferably 1 to 8% by weight.

The sulfate ion treatment can be performed by, for example, immersing the polyvinyl alcohol film in an aqueous solution containing a metal sulfate. As the metal sulfate, the following metal sulfate is preferable: the metal sulfate is easily separated into sulfate ions and metal ions in the treatment liquid, and the metal sulfate is easily introduced into the polyvinyl alcohol film in an ionic state. Examples of the metal forming the metal sulfate include alkali metals such as sodium and potassium; alkaline earth metals such as magnesium and calcium; transition metals such as cobalt, nickel, zinc, chromium, aluminum, copper, manganese, iron, and the like.

In the production of the polarizer, the zinc impregnation treatment and the sulfate ion treatment may be performed at any stage. That is, the zinc impregnation treatment and the sulfate ion treatment may be performed before the dyeing step or after the dyeing step. The zinc impregnation treatment and the sulfate ion treatment may be performed simultaneously. In the present invention, it is preferable to perform the zinc impregnation treatment and the sulfuric acid ion treatment simultaneously by using zinc sulfate as the zinc salt and the metal sulfate salt and immersing the polyvinyl alcohol film in a treatment bath containing zinc sulfate. In addition, the zinc salt and the metal sulfate may be made to coexist in the dyeing solution in advance, and the zincating treatment and/or the sulfate ion treatment may be performed simultaneously with the dyeing step. The zinc impregnation treatment and the sulfate ion treatment may be performed simultaneously with the stretching.

In the zinc impregnation treatment and the sulfate ion treatment, the zinc content and the sulfate ion content in the polarizer are adjusted by adjusting the concentrations of the zinc salt solution and the metal sulfate salt solution, the immersion temperature and the immersion time of the polyvinyl alcohol film in the treatment bath, and the like. In the zincating treatment and the sulfate ion treatment, the temperature of the zinc salt solution and the metal sulfate solution is usually about 15 to 85 ℃ and preferably 25 to 70 ℃. The immersion time is usually about 1 to 120 seconds, preferably 3 to 90 seconds. The concentrations of the zinc salt solution and the metal sulfate salt solution vary depending on the type of the zinc salt and the metal sulfate, and are usually about 0.5 to 20% by weight, preferably 1 to 10% by weight, and more preferably 2 to 7% by weight. By setting the zinc salt concentration and the metal sulfate salt concentration within these ranges, the zinc content and the sulfate ion content in the polarizer can be set within the above-described preferable ranges.

The polyvinyl alcohol film (stretched film) subjected to the above-described treatments is subjected to a water washing step and a drying step in accordance with a usual method.

The water washing step can be usually performed by immersing the polyvinyl alcohol film in a water washing bath. The water bath may be pure water or an aqueous solution of an iodide (e.g., potassium iodide, sodium iodide, etc.). The concentration of the aqueous iodide solution is preferably 0.1 to 10% by weight. An auxiliary agent such as zinc sulfate and zinc chloride may be added to the aqueous iodide solution.

The washing temperature is usually 5 to 50 ℃, preferably 10 to 45 ℃, and more preferably 15 to 40 ℃. The immersion time is usually about 10 to 300 seconds, preferably 20 to 240 seconds. The water washing step may be performed only 1 time, or may be performed a plurality of times as needed. When the water washing step is carried out a plurality of times, the kind and concentration of the additive contained in the water bath used for each treatment can be appropriately adjusted.

The step of drying the polyvinyl alcohol film may be performed by any appropriate method (for example, natural drying, air-blow drying, and heat drying). The thickness of the polarizer after the drying step is preferably 3 to 20 μm.

In the present invention, the surface modification treatment of the obtained polarizer is performed. Examples of the surface modification treatment include corona treatment, plasma treatment, and ITRO treatment, and corona treatment is particularly preferable. By performing the corona treatment, reactive functional groups such as carbonyl groups and amino groups are formed on the polarizer surface, and the adhesion to the durability-improving layer is improved. Further, impurities on the surface can be removed by ashing effect, or unevenness on the surface can be reduced, thereby producing a polarizing film having excellent appearance characteristics.

In the present invention, a polarizing film includes: a polarizer, and an adhesive layer adjacent to the polarizer or an optical film other than the polarizer. The polarizing film 10 shown in fig. 1 includes an adhesive layer adjacent to an optical film (retardation film) 4 other than the polarizer 1. The polarizing film 10 shown in fig. 2 includes an adhesive layer 5 adjacent to the polarizer 1. The adhesive layer will be described below.

< adhesive layer >

The adhesive layer is formed of a cured product layer of the adhesive composition, and particularly preferably formed of a cured product layer of an active energy ray-curable adhesive composition such as electron beam-curable, ultraviolet-curable, or visible light-curable properties. The thickness of the adhesive layer after drying is preferably 0.01 to 5 μm, and more preferably 0.01 to 3 μm, from the viewpoint of improving the appearance characteristics of the polarizing film. The active energy ray-curable adhesive composition can be classified into a radical polymerization-curable adhesive composition and a cationic polymerizable adhesive composition. In the present invention, an active energy ray having a wavelength ranging from 10nm to less than 380nm is referred to as ultraviolet ray, and an active energy ray having a wavelength ranging from 380nm to 800nm is referred to as visible light.

Examples of the monomer component constituting the radical polymerization curing adhesive composition include radical polymerizable compounds. Examples of the radical polymerizable compound include compounds having a radical polymerizable functional group having a carbon-carbon double bond such as a (meth) acryloyl group or a vinyl group. Any of a monofunctional radical polymerizable compound and a polyfunctional radical polymerizable compound having 2 or more polymerizable functional groups can be used as the monomer component. These radical polymerizable compounds may be used alone in 1 kind, or in combination with 2 or more kinds. As these radical polymerizable compounds, for example, compounds having a (meth) acryloyl group are preferable. In the present invention, (meth) acryloyl means acryloyl and/or methacryloyl, and "(meth)" means the same as defined below.

Examples of the monofunctional radical polymerizable compound include a (meth) acrylamide derivative having a (meth) acrylamide group. The (meth) acrylamide derivative is preferable in terms of securing adhesiveness to a polarizer and various transparent protective films, and in terms of high polymerization rate and excellent productivity. Specific examples of the (meth) acrylamide derivative include: n-alkyl group-containing (meth) acrylamide derivatives such as N-methyl (meth) acrylamide, N-dimethyl (meth) acrylamide, N-diethyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, and N-hexyl (meth) acrylamide; n-hydroxyalkyl (meth) acrylamide-containing derivatives such as N-methylol (meth) acrylamide, N-hydroxyethyl (meth) acrylamide, and N-methylol-N-propyl (meth) acrylamide; n-aminoalkyl-containing (meth) acrylamide derivatives such as aminomethyl (meth) acrylamide and aminoethyl (meth) acrylamide; n-alkoxy group-containing (meth) acrylamide derivatives such as N-methoxymethylacrylamide and N-ethoxymethylacrylamide; n-mercaptoalkyl-containing (meth) acrylamide derivatives such as mercaptomethyl (meth) acrylamide and mercaptoethyl (meth) acrylamide; and so on. Examples of the heterocyclic ring-containing (meth) acrylamide derivative in which the nitrogen atom of the (meth) acrylamide group forms a heterocyclic ring include: n-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylpyrrolidine and the like.

Among the above (meth) acrylamide derivatives, N-hydroxyalkyl (meth) acrylamide derivatives are preferable from the viewpoint of adhesion to polarizers and various transparent protective films, and examples of the monofunctional radical polymerizable compound include various (meth) acrylic acid derivatives having a (meth) acryloyloxy group. Specific examples thereof include: (meth) acrylic acid (1 to 20) -alkyl esters such as methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, 2-methyl-2-nitropropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, tert-pentyl (meth) acrylate, 3-pentyl (meth) acrylate, 2-dimethylbutyl (meth) acrylate, n-hexyl (meth) acrylate, hexadecyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 4-methyl-2-propylpentyl (meth) acrylate, and n-octadecyl (meth) acrylate.

Examples of the (meth) acrylic acid derivative include: cycloalkyl (meth) acrylates such as cyclohexyl (meth) acrylate and cyclopentyl (meth) acrylate; aralkyl (meth) acrylates such as benzyl (meth) acrylate; polycyclic (meth) acrylates such as 2-isobornyl (meth) acrylate, 2-norbornyl methyl (meth) acrylate, 5-norbornen-2-yl methyl (meth) acrylate, 3-methyl-2-norbornyl methyl (meth) acrylate, dicyclopentenyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, and dicyclopentanyl (meth) acrylate; (meth) acrylic esters having an alkoxy group or a phenoxy group such as 2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxymethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethyl carbitol (meth) acrylate, phenoxyethyl (meth) acrylate, and alkylphenoxypolyethylene glycol (meth) acrylate; and so on.

Further, examples of the (meth) acrylic acid derivative include: hydroxyalkyl (meth) acrylates such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 8-hydroxyoctyl (meth) acrylate, 10-hydroxydecyl (meth) acrylate, and 12-hydroxylauryl (meth) acrylate, hydroxy-containing (meth) acrylates such as [4- (hydroxymethyl) cyclohexyl ] methyl acrylate, cyclohexanedimethanol mono (meth) acrylate, and 2-hydroxy-3-phenoxypropyl (meth) acrylate; epoxy group-containing (meth) acrylates such as glycidyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate glycidyl ether; halogen-containing (meth) acrylates such as 2, 2-trifluoroethyl (meth) acrylate, 2-trifluoroethylethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, hexafluoropropyl (meth) acrylate, octafluoropentyl (meth) acrylate, heptadecafluorodecyl (meth) acrylate, and 3-chloro-2-hydroxypropyl (meth) acrylate; alkylaminoalkyl (meth) acrylates such as dimethylaminoethyl (meth) acrylate; oxygen-containing heterocyclic butyl (meth) acrylates such as 3-oxetanylmethyl (meth) acrylate, 3-methyloxetanylmethyl (meth) acrylate, 3-ethyloxetanylmethyl (meth) acrylate, 3-butyloxetanylmethyl (meth) acrylate, and 3-hexyloxetanylmethyl (meth) acrylate; and (meth) acrylates having a heterocyclic ring such as tetrahydrofurfuryl (meth) acrylate and butyrolactone (meth) acrylate, hydroxypivalic acid neopentyl glycol (meth) acrylic acid adducts, and p-phenylphenol (meth) acrylate.

Examples of the monofunctional radical polymerizable compound include: carboxyl group-containing monomers such as (meth) acrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, and isocrotonic acid.

Examples of the monofunctional radical polymerizable compound include: lactam vinyl monomers such as N-vinylpyrrolidone, N-vinyl-epsilon-caprolactam and methyl vinylpyrrolidone; vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinylpyridine

Vinyl monomers having a nitrogen-containing heterocycle such as oxazole and vinyl morpholine.

As the monofunctional radical polymerizable compound, a radical polymerizable compound having an active methylene group can be used. The radical polymerizable compound having an active methylene group is a compound having an active methylene group and an active double bond group such as a (meth) acryloyl group at a terminal or in a molecule. Examples of the active methylene group include: acetoacetyl, alkoxymalonyl, cyanoacetyl, or the like. The active methylene group is preferably an acetoacetyl group. Specific examples of the radical polymerizable compound having an active methylene group include: acetoacetoxyethyl alkyl (meth) acrylates such as 2-acetoacetoxyethyl (meth) acrylate, 2-acetoacetoxyethyl propyl (meth) acrylate, and 2-acetoacetoxyethyl-1-methylethyl (meth) acrylate; 2-ethoxymalonyloxyethyl (meth) acrylate, 2-cyanoacetoxyethyl (meth) acrylate, N- (2-cyanoacetoxyethyl) acrylamide, N- (2-propionylacetyloxybutyl) acrylamide, N- (4-acetoacetoxyethylmethylbenzyl) acrylamide, N- (2-acetoacetylaminoethyl) acrylamide, and the like. The radical polymerizable compound having an active methylene group is preferably acetoacetoxyethyl (meth) acrylate.

Further, examples of the polyfunctional radical polymerizable compound having 2 or more polymerizable functional groups include: tripropylene glycol di (meth) Acrylate, tetraethylene glycol di (meth) Acrylate, 1, 6-hexanediol di (meth) Acrylate, 1, 9-nonanediol di (meth) Acrylate, 1, 10-decanediol diacrylate, 2-ethyl-2-butylpropanediol di (meth) Acrylate, bisphenol A ethylene oxide adduct di (meth) Acrylate, bisphenol A propylene oxide adduct di (meth) Acrylate, bisphenol A diglycidyl ether di (meth) Acrylate, neopentyl glycol di (meth) Acrylate, tricyclodecane dimethanol di (meth) Acrylate, cyclic Trimethylolpropane formal (meth) Acrylate, diethylene glycol Acrylate, and the like

Alkanediol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol di (meth) acrylateEsterified product of (meth) acrylic acid and polyol such as pentaerythritol hexa (meth) acrylate or EO-modified diglycerol tetra (meth) acrylate, and 9, 9-bis [4- (2- (meth) acryloyloxyethoxy) phenyl]Fluorene. Specific examples thereof include ARONIX M-220 (manufactured by Toyo Seisakusho Co., ltd.), LIGHT ACRYLATE 1,9ND-A (manufactured by Kyowa Kabushiki Kaisha), LIGHT ACRYLATE DGE-4A (manufactured by Kyowa Kabushiki Kaisha Co., ltd.), LIGHT ACRYLATE DCP-A (manufactured by Kyowa Kabushiki Kaisha Co., ltd.), SR-531 (manufactured by Sartomer Co., ltd.), CD-536 (manufactured by Sartomer Co., ltd.), and the like. Further, as necessary, there may be mentioned: various epoxy (meth) acrylates, urethane (meth) acrylates, polyester (meth) acrylates, various (meth) acrylate monomers, and the like.

In the present invention, a polarizing film includes: and an adhesive layer adjacent to the polarizer or the optical film other than the polarizer, wherein the adhesive layer is formed of a cured product layer of an adhesive composition, and when a cured product obtained by curing the adhesive composition is immersed in pure water at 23 ℃ for 24 hours, the bulk water absorption rate represented by the following formula is preferably less than 10% by weight.

Formula (II): { (M2-M1)/M1 }. Times.100 (%)

According to this configuration, even when a specific metal component contained in the polarizer is mixed into the adhesive layer from the end, the bonding between the ionized oxalic acid and the metal component and the movement of the oxalate from the end of the polarizing film to the inside are suppressed. As a result, the appearance characteristics of the polarizing film were particularly improved even after the humidification durability test. The water absorption of the body is more preferably less than 8% by weight, particularly preferably less than 6% by weight.

In the present invention, a polarizing film includes: the (number of carbon atoms)/(number of oxygen atoms + number of nitrogen atoms) measured based on the element ratio of the adhesive layer is preferably 2.5 or more. It is considered that the bonding between the ionized oxalic acid and the metal component and the movement of the oxalate occur via water. Here, when the (number of carbon atoms)/(number of oxygen atoms + number of nitrogen atoms) of the adhesive layer measured based on the element ratio of the adhesive layer is 2.5 or more, it is possible to suppress the intrusion of water into the adhesive layer from the end portion, and in particular, in the end portion of the adhesive layer, it is possible to suppress the bonding of the ionized oxalic acid and the metal component, and further, to suppress the movement of the oxalate from the end portion of the polarizing film to the inside. As a result, the appearance characteristics of the polarizing film were significantly improved even after the humidification durability test. The method of measuring the ratio of elements in the adhesive layer will be described later.

In addition, in the present invention, a polarizing film includes: and an adhesive layer adjacent to the polarizer or the optical film other than the polarizer, wherein the adhesive layer is formed of a cured layer of the adhesive composition, and the logPow representing the octanol/water partition coefficient based on a weighted average of mole fractions of monomer components contained in the adhesive composition is preferably 1.6 or more. It is considered that the bonding between the ionized oxalic acid and the metal component and the movement of the oxalate occur via water. Here, when logPow representing the octanol/water distribution coefficient based on the weighted average of the mole fractions of the monomer components contained in the adhesive composition is 1.6 or more, it is possible to suppress the intrusion of water into the adhesive layer from the end portions, and in particular, in the end portions of the adhesive layer, it is possible to suppress the bonding of the ionized oxalic acid and the metal component, and further, to suppress the movement of the oxalate from the end portions of the polarizing film to the inside. As a result, the appearance characteristics of the polarizing film were significantly improved even after the humidification durability test.

The octanol/water partition coefficient (logPow) is an index indicating the lipophilicity of a substance and refers to the logarithmic value of the octanol/water partition coefficient. A high logPow indicates lipophilicity, i.e. a low water absorption. The logPow value can be measured (by the flask permeation method described in JIS-Z-7260) or calculated by calculation. In this specification, the logPow value calculated by Chem Draw Ultra manufactured by cambridge soft corporation is used.

The logPow of the main radical polymerizable compound is shown below. Examples thereof include: <xnotran> ( "HEAA", , logPow: -0.56), ( "DEAA", KJ , logPow: 1.69), ε - ( "PLACCEL FA1DDM", , logPow: 1.06), N- ( "Beamset 770", , logPow: -0.25), ( "ACMO", , logPow: -0.20), γ ( "GBLA", , logPow: 0.19), ( "β -CEA", , logPow: 0.2), N- ( "NVP", , logPow: 0.24), ( "AAEM", , logPow: 0.27), 2- ( "HEA", , logPow: 0.28), ( "Light Ester G", , logPow: 0.57), ( "DMAA", , logPow: 0.58), ( "Viscoat #150D", , logPow: 0.60), 4- ( "4-HBA", </xnotran> Manufactured by osaka organic chemical industry co, logPow:0.68 Acrylic acid (trade name "acrylic acid"), manufactured by mitsubishi chemical corporation, logPow:0.69 Ext> triethyleneext> glycolext> diacrylateext> (ext> tradeext> nameext> "ext> LIGHText> ACRYLATEext> 3ext> EGext> -ext> aext>"ext>,ext> productext> ofext> coyorkext> chemicalext> coext>.ext>,ext> ltdext>.ext>,ext> logpowext>:ext> 0.72 Ext> PEGext> 400ext> #ext> diacrylateext> (ext> tradeext> nameext> "ext> LIGHText> ACRYLATEext> 9ext> EGext> -ext> Aext>"ext>,ext> productext> ofext> Kyoeishaext> chemicalext> Coext>.ext>,ext> Ltdext>.ext>,ext> LogPowext>;ext> -0.1), polypropylene glycol diacrylate (trade name "aronium M-220", manufactured by east asian corp., logPow:1.68 Dicyclopentenyl acrylate (trade name "FANCRYL FA-511AS", manufactured by hitachi chemical co., logPow:2.26 BUTYL ACRYLATE (trade name "BUTYL ACRYLATE", manufactured by mitsubishi chemical corporation, logPow:2.35 1, 6-hexanediol diacrylate (trade name "LIGHT ACRYLATE 1.6HX-A", product of Kyoeisha chemical Co., ltd., logPow:2.43 Dicyclopentyl acrylate (trade name "FANCRYL FA-513AS", manufactured by hitachi chemical co., logPow:2.58 Dimethylol tricyclodecane diacrylate (trade name "LIGHT ACRYLATE DCP-a", product of coyork chemical co., ltd., logPow:3.05 Isobornyl ACRYLATE (trade name "LIGHT ACRYLATE IB-XA", manufactured by kyo chemical corporation, logPow:3.27 Hydroxypivalic acid neopentyl glycol acrylic acid adduct (trade name "LIGHT ACRYLATE HPP-a", manufactured by gory chemical co., ltd., logPow:3.35 1, 9-nonanediol diacrylate (trade name "LIGHT ACYLATE 1,9ND-A", product of Kyoeisha chemical Co., ltd., logPow:3.68 O-phenylphenol EO-modified acrylate (trade name "FANCRYL FA-301A", manufactured by Hitachi chemical Co., ltd., logPow:3.98 2-ethylhexyloxetane (trade name "Aron oxtane OXT-212", manufactured by east asian co., ltd., logPow:4.24 Bisphenol-a-diglycidyl ether (trade name "JER828", manufactured by mitsubishi chemical corporation, logPow:4.76 Bisphenol a EO6 mol-modified diacrylate (trade name "FA-326A", manufactured by hitachi chemical co., logPow:4.84 Bisphenol a EO4 mol-modified diacrylate (trade name "FA-324A", manufactured by hitachi chemical co., ltd., logPow:5.15 Bisphenol A PO2 mol-modified diacrylate (trade name "FA-P320A", manufactured by Hitachi chemical Co., ltd., logPow:6.10 Bisphenol A PO3 mol-modified diacrylate (trade name "FA-P323A", manufactured by Hitachi chemical Co., ltd., logPow:6.26 Bisphenol A PO4 mol-modified diacrylate (trade name "FA-P324A", manufactured by Hitachi chemical Co., ltd., logPow:6.43 Lauryl ACRYLATE (trade name "LIGHT ACRYLATE L-a", product of coyork chemical co., logPow: 6) Isostearyl acrylate (trade name "ISTA"), manufactured by Osaka organic chemical industries, ltd; logPow:7.46 Etc.).

The adhesive layer is formed of a cured product layer of an adhesive composition, and preferably contains 25 parts by weight or more of a monomer component having an alkyl group having 8 or more carbon atoms, based on 100 parts by weight of the total amount of the monomer components, so that logPow representing the octanol/water partition coefficient based on a weighted average of the mole fractions of the monomer components contained in the adhesive composition is 1.6 or more. Examples of the monomer component having an alkyl group having 8 or more carbon atoms include dicyclopentyl ACRYLATE (trade name "FACCRYL FA-513AS", manufactured by Hitachi chemical Co., ltd., logPow: 2.58), lauryl ACRYLATE (trade name "LIGHT ACRYLATE L-A", manufactured by Kyoeisha chemical Co., ltd., logPow: 6), isostearyl ACRYLATE (trade name "ISTA"), manufactured by Osaka organic chemical industry Co., ltd.; logPow:7.46 Etc.).

The adhesive layer is formed of a cured product layer of an adhesive composition, and the content of a monomer component having a hydroxyl group is preferably 40 parts by weight or less so that logPow representing the octanol/water partition coefficient based on the weighted average of the mole fractions of the monomer components contained in the adhesive composition is 1.6 or more. The monomer component having a hydroxyl group includes a monomer component having a hydroxyl group among the above monomer components.

In addition, in the present invention, a polarizing film includes: the adhesive layer is formed of a cured layer of an adhesive composition, and the adhesive composition preferably contains 25 parts by weight or more, more preferably 30 parts by weight or more, of a monomer component having 2 or more polymerizable functional groups, based on 100 parts by weight of the total amount of the monomer components. Even if the adhesive layer generates an oxalate, the adhesive layer has high hardness, which inhibits crystal growth of the oxalate. As a result, the generation of foreign matter due to oxalate is suppressed, and the appearance characteristics of the polarizing film are significantly improved.

Examples of the monomer component having 2 or more polymerizable functional groups include the above-mentioned polyfunctional radically polymerizable compounds having 2 or more polymerizable functional groups. In particular, when the adhesive composition contains 25 parts by weight or more of a monomer component having 2 or more polymerizable functional groups per 100 parts by weight of the total amount of the monomer components, the content of the monomer component having a hydroxyl group is preferably 40 parts by weight or less.

In the present invention, the adhesive composition which is a raw material of the adhesive layer provided in the polarizing film may contain an acrylic oligomer obtained by polymerizing a (meth) acrylic monomer, in addition to the radical polymerizable compound. By including the acrylic oligomer in the adhesive composition, curing shrinkage at the time of curing the composition by irradiation with active energy rays can be reduced, and the interface stress between the adhesive layer and an adherend such as a polarizer or an optical film can be reduced. As a result, the adhesive layer can be prevented from being deteriorated in adhesiveness to the adherend.

In view of workability and uniformity in coating, the active energy ray-curable adhesive is preferably low in viscosity, and therefore an acrylic oligomer obtained by polymerizing a (meth) acrylic monomer is also preferably low in viscosity. The weight average molecular weight (Mw) of the low-viscosity acrylic oligomer capable of preventing curing shrinkage of the adhesive layer is preferably 15000 or less, more preferably 10000 or less, and particularly preferably 5000 or less. On the other hand, in order to sufficiently suppress cure shrinkage of the cured product layer (adhesive layer), the weight average molecular weight (Mw) of the acrylic oligomer is preferably 500 or more, more preferably 1000 or more, and particularly preferably 1500 or more. Specific examples of the (meth) acrylic monomer constituting the acrylic oligomer include: (meth) acrylic acid (1-20 carbon atoms) alkyl esters such as methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, 2-methyl-2-nitropropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, sec-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-pentyl (meth) acrylate, tert-pentyl (meth) acrylate, 3-pentyl (meth) acrylate, 2-dimethylbutyl (meth) acrylate, n-hexyl (meth) acrylate, cetyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 4-methyl-2-propylpentyl (meth) acrylate, n-octadecyl (meth) acrylate, and the like, and for example: cycloalkyl (meth) acrylates (e.g., cyclohexyl (meth) acrylate, cyclopentyl (meth) acrylate, etc.), (aralkyl (meth) acrylates (e.g., benzyl (meth) acrylate, etc.), polycyclic (meth) acrylates (e.g., 2-isobornyl (meth) acrylate, 2-norbornyl methyl (meth) acrylate, 5-norborn-2-ylmethyl (meth) acrylate, 3-methyl-2-norbornyl methyl (meth) acrylate, etc.), hydroxyl-containing (meth) acrylates (e.g., hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2, 3-dihydroxypropyl methylbutyl (meth) acrylate, etc.), alkoxy-or phenoxy-containing (meth) acrylates ((meth) acrylate-2-methoxyethyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 2-methoxymethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethylcarbitol (meth) acrylate, phenoxyethyl (meth) acrylate, etc.), epoxy-containing (meth) acrylates (e.g., glycidyl (meth) acrylate, etc.), halogen-containing (meth) acrylates (e.g., 2-trifluoroethyl (meth) acrylate, 2-trifluoroethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, hexafluoropropyl (meth) acrylate, octafluoropentyl (meth) acrylate, heptadecafluorodecyl (meth) acrylate, etc.), alkylaminoalkyl (meth) acrylates (e.g., dimethylaminoethyl (meth) acrylate, etc.), and the like. These (meth) acrylates may be used alone or in combination of 2 or more. Specific examples of the acrylic oligomer (E) include "ARUFON" manufactured by Toyo Seisakusho, "ACTFLOW" manufactured by Sokko Kagaku K.K., and "JONCRYL" manufactured by BASF Japan Ltd.

The amount of the acrylic oligomer blended is preferably 15 parts by weight or less, based on 100 parts by weight of the total amount of the monomer components in the adhesive composition. When the content of the acrylic oligomer in the composition is too large, the reaction rate when the composition is irradiated with an active energy ray may be rapidly decreased, and curing may be deteriorated. On the other hand, in order to sufficiently suppress curing shrinkage of the adhesive layer, it is preferable to contain 3 parts by weight or more of the acrylic oligomer in the composition.

The photopolymerization initiator in the case of using a radical polymerizable compound can be appropriately selected depending on the active energy ray. In the case of curing by ultraviolet light or visible light, a photopolymerization initiator that is cleaved by ultraviolet light or visible light is used. Examples of the photopolymerization initiator include: benzophenone compounds such as dibenzoyl, benzophenone, benzoylbenzoic acid, and 3,3' -dimethyl-4-methoxybenzophenone; aromatic ketone compounds such as 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, α -hydroxy- α, α' -dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, and α -hydroxycyclohexyl phenyl ketone; acetophenone compounds such as methoxyacetophenone, 2-dimethoxy-2-phenylacetophenone, 2-diethoxyacetophenone, and 2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropan-1-one; benzoin ether compounds such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, and anisoin methyl ether; aromatic ketal compounds such as benzil dimethyl ketal; aromatic sulfonyl chloride compounds such as 2-naphthalenesulfonyl chloride; optically active oximes such as 1-phenyl-1, 1-propanedione-2- (o-ethoxycarbonyl) oxime; thioxanthone compounds such as thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2, 4-dimethylthioxanthone, isopropylthioxanthone, 2, 4-dichlorothioxanthone, 2, 4-diethylthioxanthone, 2, 4-diisopropylthioxanthone and dodecylthioxanthone; camphorquinone; a halogenated ketone; acyl phosphine oxides; acyl phosphonates and the like.

The amount of the photopolymerization initiator is 20% by weight or less, based on 100% by weight of the total amount of the active energy ray-curable adhesive composition. The amount of the photopolymerization initiator is preferably 0.01 to 20% by weight, more preferably 0.05 to 10% by weight, and still more preferably 0.1 to 5% by weight.

When the curable adhesive for polarizing films of the present invention is used in a visible light curable type containing a radical polymerizable compound as a curable component, it is particularly preferable to use a photopolymerization initiator having high sensitivity to light of 380nm or more. The photopolymerization initiator having high sensitivity to light of 380nm or more will be described later.

As the photopolymerization initiator, a compound represented by the following general formula (1) is preferably used alone; or a combination of a compound represented by the general formula (1) and a photopolymerization initiator having a high sensitivity to light of 380nm or more as described later.

[ chemical formula 1]

(wherein R is ¹ And R ² represents-H, -CH ₂ CH ₃ -iPr or Cl, R ¹ And R ² May be the same or different). When the compound represented by the general formula (1) is used, the adhesiveness is superior to that when a photopolymerization initiator having high sensitivity to light of 380nm or more is used alone. Among the compounds represented by the general formula (1), R is particularly preferable ¹ And R ² is-CH ₂ CH ₃ Diethyl thioxanthone (ll). The composition ratio of the compound represented by the general formula (1) in the adhesive composition is preferably 0.1 to 5 parts by weight, more preferably 0.5 to 4 parts by weight, and still more preferably 0.9 to 3 parts by weight, relative to 100 parts by weight of the total amount of the curable components.

Further, it is preferable to add a polymerization initiation aid as needed. Examples of the polymerization initiation aid include: triethylamine, diethylamine, N-methyldiethanolamine, ethanolamine, 4-dimethylaminobenzoic acid, methyl 4-dimethylaminobenzoate, ethyl 4-dimethylaminobenzoate, isoamyl 4-dimethylaminobenzoate, etc., and ethyl 4-dimethylaminobenzoate is particularly preferable. When the polymerization initiator is used, the amount thereof added is usually 0 to 5 parts by weight, preferably 0 to 4 parts by weight, and most preferably 0 to 3 parts by weight, based on 100 parts by weight of the total amount of the curable components.

Further, a known photopolymerization initiator may be used in combination as necessary. Since the transparent protective film having UV absorption ability does not transmit light of 380nm or less, it is preferable to use a photopolymerization initiator having high sensitivity to light of 380nm or more as the photopolymerization initiator. Specific examples include: 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone, 2- (dimethylamino) -2- [ (4-methylphenyl) methyl ] -1- [4- (4-morpholino) phenyl ] -1-butanone, 2,4, 6-trimethylbenzoyldiphenylphosphine oxide, bis (2, 4, 6-trimethylbenzoyl) phenylphosphine oxide, bis (. Eta.5-2, 4-cyclopentadien-1-yl) bis (2, 6-difluoro-3- (1H-pyrrol-1-yl) phenyl) titanium and the like.

In particular, as the photopolymerization initiator, in addition to the photopolymerization initiator of the general formula (1), a compound represented by the following general formula (2) is preferably further used,

[ chemical formula 2]

(in the formula, R ³ 、R ⁴ And R ⁵ Represents H, -CH ₃ 、-CH ₂ CH ₃ -iPr or Cl, R ³ 、R ⁴ And R ⁵ May be the same or different). As the compound represented by the general formula (2), commercially available 2-methyl-1- (4-methylthiophenyl) -2-morpholinopropan-1-one (trade name: IRGACURE 907 manufacturer: BASF) can be suitably used. Further, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -1-butanone (trade name: IRGACURE 369 manufacturer: BASF), 2- (dimethylamino) -2- [ (4-methylphenyl) methyl group]-1- [4- (4-morpholinyl) phenyl]-1-butanone (trade name: IRGACURE 379 manufacturer: BASF) is preferred due to its high sensitivity.

In the present invention, among the above photopolymerization initiators, a hydroxyl group-containing photopolymerization initiator is preferably used. When the active energy ray-curable adhesive composition contains a hydroxyl group-containing photopolymerization initiator as a polymerization initiator, the solubility of the adhesive layer having a high concentration of the component a on the polarizer side is improved, and the curability of the adhesive layer is improved. Examples of the photopolymerization initiator having a hydroxyl group include: 2-methyl-2-hydroxypropiophenone (trade name "DAROCUR1173", manufactured by BASF), 1-hydroxycyclohexyl phenyl ketone (trade name "IRGACURE184", manufactured by BASF), 1- [4- (2-hydroxyethoxy) -phenyl ] -2-hydroxy-2-methyl-1-propan-1-one (trade name "IRGACURE2959", manufactured by BASF), 2-hydroxy-1- {4- [4- (2-hydroxy-2-methyl-propionyl) -benzyl ] phenyl } -2-methyl-propan-1-one (trade name "IRGACURE127", manufactured by BASF), and the like. In particular, 1-hydroxycyclohexylphenyl ketone is more preferable because it has particularly excellent solubility in an adhesive layer having a high concentration of component A.

The cationically polymerizable compound used in the cationically polymerizable adhesive composition can be classified into a monofunctional cationically polymerizable compound having 1 cationically polymerizable functional group in the molecule and a polyfunctional cationically polymerizable compound having 2 or more cationically polymerizable functional groups in the molecule. Since the monofunctional cationic polymerizable compound has a low liquid viscosity, the liquid viscosity of the resin composition can be reduced by adding the monofunctional cationic polymerizable compound to the resin composition. Further, the monofunctional cationically polymerizable compound often has a functional group that can exhibit various functions, and by including the monofunctional cationically polymerizable compound in the cationically polymerizable adhesive composition, various functions can be exhibited in the cationically polymerizable adhesive composition and/or the cured product of the cationically polymerizable adhesive composition. The polyfunctional cationically polymerizable compound is preferably contained in a cured product of the cationically polymerizable adhesive composition because the polyfunctional cationically polymerizable compound can 3-dimensionally crosslink the cured product of the cationically polymerizable adhesive composition. The ratio of the monofunctional cationic polymerizable compound to the polyfunctional cationic polymerizable compound is preferably in the range of 10 parts by weight to 1000 parts by weight based on 100 parts by weight of the monofunctional cationic polymerizable compound. Examples of the cationically polymerizable functional group include an epoxy group, an oxetane group, and a vinyl ether group. Examples of the compound having an epoxy group include an aliphatic epoxy compound, an alicyclic epoxy compound, and an aromatic epoxy compound, and since the compound has excellent curability and adhesiveness, it is particularly preferable to contain an alicyclic epoxy compound as the cationically polymerizable adhesive composition of the present invention. Examples of the alicyclic epoxy compound include 3, 4-epoxycyclohexylmethyl-3, 4-epoxycyclohexanecarboxylate, a caprolactone-modified product of 3, 4-epoxycyclohexylmethyl-3, 4-epoxycyclohexanecarboxylate, a trimethylcaprolactone-modified product, a valerolactone-modified product, and the like, and specifically include CELLOXIDE 2021, CELLOXIDE 2021A, CELLOXIDE 2021P, CELLOXIDE2081, CELLOXIDE 2083, CELLOXIDE 2085 (the above is made by Daiiluo Chemicals Co., ltd.), cyracure UVR-6105, cyracure UVR-6107, cyracure 30, R-6110 (the above is made by Dow Chemical Japan Ltd.). The compound having an oxetanyl group is preferably contained because of the effect of improving the curability of the cationic polymerization curable adhesive composition and reducing the liquid viscosity of the composition. Examples of the oxetanyl group-containing compound include 3-ethyl-3-hydroxymethyloxetane, 1, 4-bis [ (3-ethyl-3-oxetanyl) methoxymethyl ] benzene, 3-ethyl-3- (phenoxymethyl) OXETANE, bis [ (3-ethyl-3-oxetanyl) methyl ] ether, 3-ethyl-3- (2-ethylhexyloxymethyl) OXETANE, novolak OXETANE and the like, and are commercially available as ARON OXETANE ox-101, ARON OXETANE ox-121, ARON OXETANE ox-211, ARON OXETANE ox-221 and ARON OXETANE ox-212 (available from east asia corporation). The compound having a vinyl ether group is preferably contained because of the effects of improving the curability of the cationically polymerizable adhesive composition and reducing the liquid viscosity of the composition. Examples of the compound having a vinyl ether group include 2-hydroxyethyl vinyl ether, diethylene glycol monovinyl ether, 4-hydroxybutyl vinyl ether, diethylene glycol monovinyl ether, triethylene glycol divinyl ether, cyclohexanedimethanol monovinyl ether, tricyclodecane vinyl ether, cyclohexyl vinyl ether, methoxyethyl vinyl ether, ethoxyethyl vinyl ether, pentaerythritol-type tetravinyl ether, and the like.

The cationically polymerizable adhesive composition contains at least 1 compound selected from the compounds having epoxy groups, oxetanyl groups and vinyl ether groups described above as a curable component, and is cured by cationic polymerization, and therefore a photo cationic polymerization initiator is blended. The photo cation polymerization initiator generates a cation species or lewis acid by irradiation of active energy rays such as visible light, ultraviolet rays, X-rays, electron beams, and the like, thereby initiating polymerization of an epoxy group or an oxetanyl group. As the photo cation polymerization initiator, a photo acid generator described later can be suitably used. In addition, in the case of using the cationic polymerizable adhesive composition as the visible light-curable, it is particularly preferable to use a photo cationic polymerization initiator having high sensitivity to light of 380nm or more, but since the photo cationic polymerization initiator is a compound which usually exhibits a maximum absorption in the vicinity of 300nm or a wavelength region shorter than 300nm, by blending a photosensitizer which exhibits a maximum absorption in a wavelength region longer than that, specifically, in a wavelength region longer than 380nm, it is possible to sense light of a wavelength in the vicinity thereof and promote generation of cationic species or acid from the photo cationic polymerization initiator. As the photosensitizer, for example: anthracene compounds, pyrene compounds, carbonyl compounds, organic sulfur compounds, sulfides, redox compounds, azo and diazo compounds, halogen compounds, photoreducing pigments, etc., and these may be mixed with 2 or more of them. Particularly, anthracene compounds are preferable because they are excellent in photosensitizing effect, and specifically Anthracure UVS-1331 and Anthracure UVS-1221 (manufactured by Kawasaki chemical Co., ltd.) are mentioned. The content of the photosensitizer is preferably 0.1 to 5 wt%, more preferably 0.5 to 3 wt%.

< optical film >

In the present invention, examples of the optical film provided in the polarizing film include: transparent protective film, phase difference film. In addition, the surface modification treatment may be performed not only on the polarizer but also on the optical film. The surface modification treatment includes corona treatment, plasma treatment, and ITRO treatment, and particularly corona treatment is preferable.

As a material of the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like can be used. Specific examples of such thermoplastic resins include cellulose resins such as cellulose triacetate, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, cyclic polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The transparent protective film may contain 1 or more kinds of any appropriate additives. Examples of additives include: ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, colorants, and the like. The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, even more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. When the content of the thermoplastic resin in the transparent protective film is 50 wt% or less, there is a fear that high transparency and the like originally possessed by the thermoplastic resin cannot be sufficiently expressed.

The material for forming the transparent protective film is preferably excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like, and particularly, the moisture permeability is more preferably 150g/m ² Less than 24h, particularly preferably 140g/m ² A total of 24 hours or less, more preferably 120g/m ² The time is less than 24h.

A functional layer such as a hard coat layer, an antireflection layer, an anti-blocking layer, a diffusion layer, or an antiglare layer may be provided on the surface of the transparent protective film which is not bonded to the polarizer. The functional layers such as the hard coat layer, the antireflection layer, the anti-blocking layer, the diffusion layer, and the antiglare layer may be provided to protect the transparent protective film itself, or may be provided separately from the transparent protective film.

The thickness of the transparent protective film may be suitably determined, and is generally about 1 to 500 μm, preferably 1 to 300 μm, and more preferably 5 to 200 μm in view of strength, handling properties such as handling properties, and thin layer properties. More preferably 10 to 200. Mu.m, still more preferably 20 to 80 μm.

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

Examples of the retardation film include: a birefringent film obtained by uniaxially or biaxially stretching a polymer material, an alignment film of a liquid crystal polymer, and a retardation film obtained by supporting an alignment layer of a liquid crystal polymer with a film. The thickness of the retardation film is not particularly limited, and is generally about 20 to 150 μm.

As the retardation film, a reverse wavelength dispersion type retardation film satisfying the following formulas (1) to (3) can be used:

0.70＜Re[450]/Re[550]＜0.97···(1)

1.5×10 ^-3 ＜Δn＜6×10 ^-3 ···(2)

1.13＜NZ＜1.50···(3)

(wherein Re 450 and Re 550 are in-plane phase difference values of the retardation film measured at 23 ℃ by light having wavelengths of 450nm and 550nm, respectively; Δ n is in-plane birefringence, which is nx-ny when the refractive indices of the retardation film in the slow axis direction and the fast axis direction are nx and ny, respectively; and NZ is the ratio of nx-NZ and nx-ny when NZ is the refractive index of the retardation film in the thickness direction, where nx-NZ is the thickness direction birefringence, and nx-ny is the in-plane birefringence).

The polarizing film of the present invention can be produced, for example, by the following production method.

A method for manufacturing a polarizing film, the polarizing film comprising: a polarizer and an adhesive layer adjacent to a1 st optical film other than the polarizer, the method comprising: a1 st bonding step of bonding the polarizer and the 1 st optical film together via an aqueous adhesive layer; and a 2 nd bonding step of bonding the 1 st optical film and the 2 nd optical film together via the adhesive layer. The polarizer preferably contains a metal component capable of forming a divalent metal cation in water, particularly zinc. The adhesive layer is preferably formed by a cured product layer of an active energy ray-curable adhesive composition.

The polarizing film of the present invention can be produced by the following production method, for example.

A method for manufacturing a polarizing film, the polarizing film comprising: a polarizer and an adhesive layer adjacent to the polarizer, the method comprising: and a1 st bonding step of bonding the polarizer and the 1 st optical film together via the adhesive layer. The polarizer preferably contains a metal component capable of forming a divalent metal cation in water, particularly zinc. The adhesive layer is preferably formed by a cured product layer of an active energy ray-curable adhesive composition.

In the above-described bonding step, various adhesive compositions are applied to an adherend such as a polarizer or an optical film, the adherend such as a polarizer or an optical film is bonded, and the adhesive compositions are cured. The method of applying the adhesive composition may be appropriately selected depending on the viscosity of the adhesive composition and the target thickness, and examples thereof include: reverse coaters, gravure coaters (direct, reverse, or offset), bar reverse coaters, roll coaters, die coaters, wire wound bar coaters, and the like. The adhesion of an adherend such as a polarizer and an optical film can be performed by a roll laminator or the like.

The adhesive layer is formed of a cured product layer of the adhesive composition, and particularly preferably formed of a cured product layer of an active energy ray-curable adhesive composition such as electron beam-curable, ultraviolet-curable, or visible light-curable. In the bonding step, the adhesive composition is cured by irradiation with active energy rays (e.g., electron beams, ultraviolet rays, and visible light) to form an adhesive layer. The irradiation direction of the active energy ray (electron beam, ultraviolet ray, visible light, etc.) may be from any appropriate direction. When the polarizing film of the present invention is produced by a continuous production line, the line speed varies depending on the curing time of the adhesive composition, and is preferably 5 to 100m/min, more preferably 10 to 50m/min, and still more preferably 20 to 30m/min. When the linear velocity is too low, productivity is insufficient, or damage to the transparent protective film is too large, and a polarizing film that can withstand a durability test or the like cannot be produced. When the line speed is too high, the curing of the curable resin composition may be insufficient, and the desired adhesiveness may not be obtained.

The polarizing film of the present invention can be used as an optical film laminated with other optical layers in actual use. The optical layer is not particularly limited, and optical layers used in the formation of liquid crystal display devices and the like may be used, for example, 1 or 2 or more layers of reflective plates, semi-transmissive plates, retardation plates (including 1/2 wave plates, 1/4 wave plates, and other wave plates), viewing angle compensation films, and the like. In particular, a reflective polarizing film or a semi-transmissive polarizing film in which a reflective plate or a semi-transmissive reflective plate is further laminated on the polarizing film of the present invention, an elliptical polarizing film or a circular polarizing film in which a phase difference plate is further laminated on the polarizing film, a wide-angle polarizing film in which a viewing angle compensation film is further laminated on the polarizing film, or a polarizing film in which a brightness enhancement film is further laminated on the polarizing film is preferable.

The optical film in which the above optical layers are laminated on the polarizing film may be formed by laminating the optical layers one by one in order in the manufacturing process of a liquid crystal display device or the like, but when the optical film is laminated in advance, there is an advantage that the quality stability, the assembling operation, and the like are excellent, and the manufacturing process of the liquid crystal display device or the like can be improved. For lamination, an appropriate bonding method such as an adhesive layer can be used. When the polarizing film or the other optical film is bonded, the optical axes thereof may be arranged at an appropriate angle according to the target retardation characteristics.

An adhesive layer for adhesion to other members such as a liquid crystal cell may be provided on the polarizing film or the optical film in which at least 1 polarizing film is laminated. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited, and for example, a pressure-sensitive adhesive using a polymer such as an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine polymer, or a rubber as a base polymer can be suitably selected and used. In particular, an acrylic pressure-sensitive adhesive, which is excellent in optical transparency, exhibits appropriate adhesive properties such as wettability, cohesiveness and adhesiveness, and is excellent in weather resistance and heat resistance, can be preferably used.

The adhesive layer may be provided on one side or both sides of the polarizing film or the optical film in the form of a laminated layer of layers of different compositions, kinds, or the like. In addition, when the polarizing film and the optical film are provided on both surfaces, adhesive layers having different compositions, kinds, thicknesses, and the like may be formed on the front and back surfaces of the polarizing film and the optical film. The thickness of the adhesive layer may be suitably determined depending on the purpose of use, adhesion, and the like, and is usually 1 to 100 μm, preferably 5 to 30 μm, and particularly preferably 10 to 20 μm.

The exposed surface of the adhesive layer is temporarily adhered to and covered with the separator for the purpose of preventing contamination of the exposed surface until the adhesive layer is actually used. This prevents contact with the adhesive layer in a normal processing state. As the separator, a conventionally specified suitable separator such as a separator obtained by coating a suitable thin layer body such as a plastic film, a rubber sheet, paper, cloth, nonwoven fabric, a net, a foamed sheet, a metal foil, or a laminate thereof with a suitable release agent such as silicone, long-chain alkyl, fluorine, or molybdenum sulfide, if necessary, can be used in addition to the above thickness conditions.

The polarizing film or optical film of the present invention can be preferably used for formation of various devices such as a liquid crystal display device. The liquid crystal display device can be formed according to a conventional method. That is, the liquid crystal display device is generally formed by appropriately assembling a liquid crystal cell with a polarizing film or an optical film and, if necessary, components such as an illumination system, and incorporating a driver circuit, and the like. As the liquid crystal cell, any type of liquid crystal cell such as TN type, STN type, pi type, or the like can be used.

A suitable liquid crystal display device such as a liquid crystal display device in which a polarizing film or an optical film is disposed on one side or both sides of a liquid crystal cell, a liquid crystal display device using a backlight or a reflector in an illumination system, or the like can be formed. In this case, the polarizing film or the optical film of the present invention may be disposed on one side or both sides of the liquid crystal cell. In the case where a polarizing film or an optical film is provided on both sides, they may be the same or different. Further, in the formation of the liquid crystal display device, appropriate members such as a diffusion plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusion plate, and a backlight may be disposed in appropriate positions in 1 layer or 2 layers or more.

Examples

Examples of the present invention are described below, but the embodiments of the present invention are not limited to these examples.

< manufacture of polarizer >

A polyvinyl alcohol film having an average degree of polymerization of 2700 and a thickness of 45 μm was stretched and conveyed while being dyed between rolls having different peripheral speed ratios. First, after the polyvinyl alcohol film was stretched 1.2 times in the transport direction while being swollen by immersing in a water bath at 30 ℃ for 1 minute (1 st stretching), the film was stretched 3 times in the transport direction (based on the unstretched film) while being dyed by immersing in an aqueous solution (liquid temperature 30 ℃) of potassium iodide (0.03 wt%) and iodine (0.3 wt%) for 1 minute (2 nd stretching). Next, the stretched film was stretched 6 times (based on an unstretched film) in the conveyance direction while being immersed in an aqueous solution (bath) of boric acid (4 wt%), potassium iodide (5 wt%), and zinc sulfate (3.5 wt%) for 30 seconds (No. 3 stretching). The stretched film was dried, whereby polarizer 1 was obtained. The thickness of the polarizer 1 after drying was 18 μm. A polarizer 2 was obtained by the same production method as the polarizer 1 except that a polyvinyl alcohol film having a thickness of 30 μm was used. The thickness of the polarizer 2 after drying was 12 μm.

< active energy ray >

As the active energy ray, a visible light (metal halide lamp in which gallium is sealed) irradiation device was used: fusion uv systems, inc. Light HAMMER10, valve: v valve, peak illuminance: 1600mW/cm ² Cumulative dose of radiation 1000/mJ/cm ² (wavelength 380-440 nm). The illuminance of visible light was measured by using the Sola-Check system manufactured by solaell corporation.

< method for measuring element ratio of adhesive layer >

The element ratio of the adhesive layer included in the polarizing film was measured by the following measurement method.

First, in both of the following polarizing film configuration (1) and polarizing film configuration (2), an adhesive that does not constitute a polarizing film was applied to the 2 nd optical film surface and fixed to a metal support base. Next, the pressure-sensitive adhesive and the 1 st optical film or the 2 nd optical film were removed by a microtome, and the pressure-sensitive adhesive layer to be measured was exposed. Then, ar-GCIB etching was performed, and the exposed adhesive layer after the Ar-GCIB etching was pressed against the sample table by a Mo plate and fixed. Then, ESCA analysis was performed using a scanning X-ray photoelectron spectrometer (Quantum 2000, manufactured by ULVAC-PHI.), and a wide-scanning measurement was performed to perform qualitative analysis. Further, the carbon element, the oxygen element, and the nitrogen element were measured by narrow scanning, and the element ratio (atomic%) was calculated. From the obtained carbon element ratio (atomic%), oxygen element ratio (atomic%), and nitrogen element ratio (atomic%), the (number of carbon atoms)/(number of oxygen atoms + number of nitrogen atoms) was calculated.

< test of lighting panel >

An on-board dashboard monitor (TKH 703) manufactured by MAXWIN corporation was disassembled, and the liquid crystal panel was taken out. The polarizing film attached to the visible side of the liquid crystal panel was peeled off, and instead, the polarizing films of the respective examples and comparative examples were cut into the same size as the polarizing film peeled off from the liquid crystal panel, and were attached via an adhesive layer (thickness 20 μm) in the same manner as the peeled polarizing film in the transmission axis, to obtain a liquid crystal panel.

The liquid crystal panel obtained above was placed in an environment of 65 ℃ and 95% for 1000 hours and left to stand in a normal temperature and normal humidity environment for 24 hours. Then, the liquid crystal panel was again attached to a monitor case obtained by disassembling the liquid crystal panel, and a black image was displayed and confirmed by visual observation. As a result, a case where only the black screen is displayed is indicated by o, and a case where a white fog display failure occurs in a part of the screen is indicated by x.

< 3 rd optical film >

The 3 rd optical film used in the polarizing film configuration (1) described below was produced by the following production method.

An autoclave equipped with a stirrer, a condenser, a nitrogen inlet and a thermometer was charged with 48 parts by weight of hydroxypropylmethylcellulose (product name: methosose 60SH-50, manufactured by shin-Etsu chemical Co., ltd.), 15601 parts by weight of distilled water, 8161 parts by weight of diisopropyl fumarate, 240 parts by weight of 3-ethyl-3-oxetanylmethyl acrylate and 45 parts by weight of t-butyl peroxypivalate as a polymerization initiator, and subjected to nitrogen bubbling for 1 hour, followed by stirring and holding at 49 ℃ for 24 hours, thereby carrying out radical suspension polymerization. Subsequently, the mixture was cooled to room temperature, and the resulting suspension containing the polymer particles was centrifuged. The obtained polymer was washed with distilled water 2 times and methanol 2 times, and then dried under reduced pressure.

The obtained fumarate resin (polymer having negative birefringence) was dissolved in a toluene/methyl ethyl ketone mixed solution (toluene/methyl ethyl ketone 50 wt%/50 wt%), to prepare a 20% solution. Further, 5 parts by weight of tributyl trimellitate was added as a plasticizer to 100 parts by weight of the fumarate resin to prepare a cement.

As the support film, a biaxially oriented film (75 μm thick and 1350mm wide) of polyester (polyethylene terephthalate/ethylene isophthalate copolymer) was used. The tensile Modulus (MD) of the support at 140 ℃ is 800MPa.

The wound body of the support film is set in a feeding section of the film forming apparatus, and is subjected to a heating treatment in a heating furnace while being fed and conveyed to the downstream side. The temperature of the heat treatment is adjusted by changing the temperature of the atmosphere in the heating furnace. The heating time is adjusted by changing the transport speed of the support. The cement prepared in Synthesis example A was coated on the heated support so that the dried film thickness became 6.3. Mu.m, and dried at 140 ℃. The dried coating film is wound into a laminate together with a support.

The laminate was set in the feeding section of the stretching apparatus, and while being fed and conveyed to the downstream side, free-end uniaxial stretching was performed in a stretching furnace at a temperature of 140 ℃. The support was peeled from the stretched laminate to obtain a retardation film having a thickness of 6 μm. The stretching ratio was adjusted so that the in-plane retardation of the retardation film after the support was peeled off became 35 nm.

Example 1

As the adhesive, an aqueous solution containing a polyvinyl alcohol resin having an acetoacetyl group (average polymerization degree 1200, saponification degree 98.5 mol%, acetoacetylation degree 5 mol%) and methylol melamine at a weight ratio of 3. Using this adhesive, a 2 nd optical film (a cellulose triacetate film with a hard coat layer (trade name "TG40UL", film thickness 40 μm) was bonded to one surface (one surface on the visible side) of the polarizer 1 by a roll laminator at a temperature of 30 ℃, and a1 st optical film (a cycloolefin film with a retardation (trade name "ZT12", film thickness 17 μm ", manufactured by japan rayleigh corporation)) was bonded to the other surface (the image display unit side surface) of the polarizer 1, and then heated and dried in an oven, thereby producing a laminated film in which optical films were laminated on both surfaces of the polarizer.

Then, an adhesive composition adjusted to the compounding amount shown in Table 1 was applied to the cycloolefin film side having a retardation of the laminated film obtained above using an MCD coater (manufactured by Fuji mechanical Co., ltd.) (cell shape: the number of honeycomb and gravure rolls: 1000 pieces/inch, rotation speed 140%/line speed), and the resultant film was laminated on the 3 rd optical film (film thickness: 6 μm) by a roll coater so that the thickness thereof became 1 μm. Then, the adhesive composition was cured by irradiation with the above visible light from the 3 rd optical film side using an active energy ray irradiation apparatus, and then hot-air dried at 70 ℃ for 3 minutes to obtain a polarizing film (the polarizing film having this composition was referred to as "polarizing film composition (1)"). The thickness of the adhesive layer after drying was 1 μm, and the lamination was performed at a lamination line speed of 25 m/min.

The polarizing film of example 1 produced was bonded to one surface of alkali-free glass having a thickness of 0.7mm via an adhesive layer (thickness: 20 μm), thereby preparing a sample for evaluation of a humidification durability test. After the sample was put into an environment of 65 to 95% humidity, a humidification durability test of exposure for 1000 hours was performed. The samples for evaluation of the humidified durability test after the durability test were subjected to bonding of a cross nicol polarizing film via an adhesive layer (thickness 20 μm) so that the transmission axes of the respective polarizing films were perpendicular to each other, to the other side of the alkali-free glass to which the polarizing film of example 1 was bonded, and then placed on a backlight (the polarizing film of example 1 was the upper surface), and the polarizing film of example 1 was visually observed to examine the presence or absence of the occurrence of a bright point originating from a foreign substance.

It is found that the polarizing film of example 1 has no bright point from a foreign substance more than 3mm from the end face after the humidification durability test in which the polarizing film is exposed to an environment of 65 to 95% humidity for 1000 hours.

Example 2

As the adhesive, an aqueous solution of a polyvinyl alcohol resin containing acetoacetyl groups (average polymerization degree 1200, saponification degree 98.5 mol%, acetoacetylation degree 5 mol%) and methylolmelamine at a weight ratio of 3. Using this adhesive, a 2 nd optical film (a hard-coated cellulose triacetate film (manufactured by fuji film co., ltd., trade name "TG40UL", film thickness 40 μm)) was bonded to one surface (visible side surface) of a polarizer 1 by a roll laminator under a temperature condition of 30 ℃, and then heated and dried in an oven, thereby producing a laminated film in which the optical film is laminated to one surface of the polarizer.

Next, an adhesive composition adjusted to the blending amount shown in table 1 was applied to the polarizer 1 side of the laminated film using an MCD coater (manufactured by fuji machine corporation) (cell shape: number of lines of honeycomb and gravure roll: 1000 pieces/inch, rotation speed 140%/line speed), and the laminated film was bonded to a1 st optical film (cycloolefin film (product name "ZF14", manufactured by ZEON corporation, japan, film thickness 13 μm)) by a roll coater so that the thickness thereof became 1 μm. Then, the adhesive composition was cured by irradiation with the visible light from the cycloolefin film side using an active energy ray irradiation apparatus, and then dried with hot air at 70 ℃ for 3 minutes, to obtain a polarizing film (the polarizing film having this configuration was referred to as "polarizing film configuration (2)"). The thickness of the adhesive layer after drying was 1 μm. The lamination was carried out at a lamination line speed of 25 m/min.

The polarizing film of example 4 thus produced was subjected to a humidity durability test of exposure to an environment of 65 to 95% humidity for 1000 hours in the same manner as in example 1, and the presence or absence of the occurrence of a bright point derived from a foreign substance was visually observed.

It is found that the polarizing film of example 2 has no bright point derived from a foreign substance more than 3mm from the end face after the humidification durability test of 1000 hours of exposure to the environment of 65 to 95% humidity.

Examples 3 to 6 and comparative examples 1 to 6

The presence or absence of the occurrence of a bright spot due to a foreign substance was observed in the same manner as in examples 1 to 2, except that the composition of the polarizing film, the blending of the adhesive composition, and the kind of polarizer were changed to the conditions described in table 1.

The details of each component described in table 1 are as follows.

(monofunctional radical polymerizable Compound)

Unsaturated fatty acid hydroxyalkyl ester-modified epsilon-caprolactone (monomer component having a hydroxyl group) (trade name "PLACCEL FA1DDM", manufactured by Daiiol Co., ltd., molecular weight 230.26, logPow: 1.06)

Acryloylmorpholine (trade name: ACMO, product of Kyoho Co., ltd., molecular weight 141.17, logPow: -0.20)

Diethylacrylamide (trade name "DEAA", manufactured by KJ chemical Co., ltd., molecular weight 127.18, logPow: 1.69)

Lauryl ACRYLATE (trade name "LIGHT ACRYLATE L-A", product of Kyoeisha chemical Co., ltd., molecular weight 240.39, logPow: 6)

Isostearyl acrylate (trade name "ISTA"), manufactured by osaka organic chemical industries, ltd, molecular weight 324.5, logPow: 7.46)

Dicyclopentyl acrylate (trade name "FANCRYL FA-513AS", manufactured by Hitachi chemical Co., ltd., molecular weight 206.28, logPow: 2.58)

(polyfunctional radical polymerizable Compound)

Ext> PEGext> 400ext> #ext> diacrylateext> (ext> tradeext> nameext> "ext> LIGHText> ACRYLATEext> 9ext> EGext> -ext> Aext>"ext>,ext> manufacturedext> byext> Kyoeishaext> chemicalext> Coext>.ext>,ext> Ltdext>.ext>,ext> molecularext> weightext> 536.61ext>,ext> LogPowext>:ext> -ext> 0.1ext>)ext>

Polypropylene glycol diacrylate (trade name "ARONIX M-220", manufactured by Toyo Synthesis Co., ltd., molecular weight 300.35, logPow: 1.68)

1, 9-nonanediol diacrylate (trade name "LIGHT ACRYLATE 1,9ND-A", available from Kyoho chemical Co., ltd., molecular weight 268.35, logPow: 3.68)

Dimethylol tricyclodecane diacrylate (trade name "LIGHT ACRYLATE DCP-A", of Kyoeisha chemical Co., ltd., molecular weight 304.38, logPow: 3.05)

(acrylic acid oligomer)

A34/66 molar ratio copolymer oligomer of butyl acrylate and butyl methacrylate (trade name "ARUFON UP-1190", manufactured by TOYOBO SYNTHETIC CO., LTD., molecular weight 1700, logPow: 1.95)

(initiator)

2-methyl-1- [4- (methylthio) phenyl ] -2-morpholinopropan-1-one (trade name "Omnirad 907", manufactured by IGM Resins B.V., inc., molecular weight 279.13, logPow: 2.09)

Diethyl thioxanthone (trade name "KAYACURE DETX-S", manufactured by Nippon chemical Co., ltd., molecular weight 268.37, logPow: 5.12)

In table 1, "the number of carbon atoms)/(the number of oxygen atoms + the number of nitrogen atoms" means a value calculated based on the above-mentioned "method of measuring the element ratio of adhesive layer", the "average logPow" means a logPow indicating an octanol/water distribution coefficient based on a weighted average of the mole fractions of the monomer components contained in the adhesive composition ", and the" distance (μm) from the edge face to the foreign object "means a distance from the edge face of the polarizing film to a bright point from the foreign object, which is observed", respectively.

Claims

1. A polarizing film comprising:

a polarizer, and

an adhesive layer adjacent to the polarizer or the optical film other than the polarizer,

the polarizing film has no bright point from foreign matter more than 3mm from the end face after being exposed to a humidification durability test for 1000 hours in an environment of 65-95% humidity.

2. The polarizing film of claim 1,

the polarizer contains a metal component capable of becoming a divalent metal cation in water.

3. The polarizing film of claim 2,

the metal component is zinc.

4. The polarizing film according to any one of claims 1 to 3,

the polarizing film is provided with:

a polarizer,

5. The polarizing film according to any one of claims 1 to 4,

the adhesive layer is formed from a cured product layer of an active energy ray-curable adhesive composition.

6. The polarizing film according to any one of claims 1 to 5,

the adhesive layer is formed of a cured product layer of an adhesive composition, and when a cured product obtained by curing the adhesive composition is immersed in pure water at 23 ℃ for 24 hours, the bulk water absorption rate represented by the following formula is less than 10% by weight,

formula (II): { (M2-M1)/M1 }. Times.100 (%)

7. The polarizing film according to any one of claims 1 to 5,

(number of carbon atoms)/(number of oxygen atoms + number of nitrogen atoms) measured based on the ratio of elements in the adhesive layer is 2.5 or more.

8. The polarizing film according to any one of claims 1 to 6,

the adhesive layer is formed from a cured product layer of an adhesive composition, and the logPow representing the octanol/water partition coefficient based on the weighted average of the mole fractions of the monomer components contained in the adhesive composition is 1.6 or more.

9. The polarizing film of claim 8,

the adhesive composition contains 25 parts by weight or more of a monomer component having an alkyl group having 8 or more carbon atoms, based on 100 parts by weight of the total monomer component.

10. The polarizing film of claim 8 or 9,

the adhesive composition contains 40 parts by weight or less of a monomer component having a hydroxyl group, based on 100 parts by weight of the total monomer component.

11. An optical film comprising at least 1 polarizing film according to any one of claims 1 to 10 laminated thereon.

12. An image display device using the polarizing film according to any one of claims 1 to 10 and/or the optical film according to claim 11.