JP6741477B2 - Polarizing film, polarizing film with adhesive layer, and image display device - Google Patents

Description

The present invention relates to a polarizing film and a polarizing film with a pressure-sensitive adhesive layer having the polarizing film and a pressure-sensitive adhesive layer. The present invention also relates to an image display device including the polarizing film with an adhesive layer.

A polarizing film is used for displaying images in various image display devices. For example, in a liquid crystal display (LCD), it is indispensable to dispose polarizing films on both sides of a glass substrate forming the surface of a liquid crystal panel due to its image forming method. Further, in the organic EL display device, in order to shield specular reflection of external light at the metal electrode, a circularly polarizing film in which a polarizing film and a quarter wavelength plate are laminated is arranged on the viewing side of the organic light emitting layer.

As the polarizing film, generally, one or both surfaces of a polarizer made of a dichroic material such as a polyvinyl alcohol film and iodine, a protective film bonded with a polyvinyl alcohol adhesive or the like is used. ing.

In the harsh environment of thermal shock (for example, a heat shock test in which temperature conditions of −40° C. and 85° C. are repeated), the polarizing film is changed in the contraction stress of the polarizer so that the entire absorption axis direction of the polarizer is affected. There is a problem that cracks (penetration cracks) are likely to occur. Therefore, in order to suppress the shrinkage of the polarizer and reduce the effect of thermal shock, the polarizing film is usually coated with a 40 to 80 μm triacetyl cellulose (TAC) film as a protective film on both surfaces of the polarizer. A combined laminate is used. However, even with the polarizing film protected on both sides, the change in shrinkage stress of the polarizer is not negligible, it is difficult to completely suppress the effect of shrinkage, to some extent in the optical film laminate containing the polarizer. It was unavoidable that the contraction of the.

On the other hand, in recent years, thinning of image display devices such as liquid crystal display devices has progressed, and accordingly, thinner polarizers have been required. In the case of a thin polarizer having a thickness of 10 μm or less, a change in shrinkage stress is small, so that a through crack is less likely to occur. For example, there is disclosed a polarizing film in which a protective film is attached to one side or both sides of a thin polarizer having a thickness of 10 μm or less, and generation of a through crack is suppressed (for example, refer to Patent Document 1). In particular, if the protective film is a double-sided protective polarizing film laminated on both sides of the thin polarizer, the protective film provided on both sides, because it is possible to suppress the amount of shrinkage of the polarizer during the heat shock test, through cracks Can be effectively suppressed.

JP, 2005-152911, A

However, on the other hand, a thin polarizer having a thickness of 10 μm or less has a problem that its optical characteristics are easily deteriorated in a humid environment. Therefore, even in the double-sided protective polarizing film using the thin polarizer described in Patent Document 1 or the like, depending on the type of the protective film, the polarizer deteriorates due to moisture in a humid environment, and the optical characteristics of the polarizing film. Will be significantly reduced.

Therefore, for the purpose of suppressing the deterioration of the polarizer due to such water, the moisture permeability is extremely low (specifically, 30 g/(m ² ·day) or less as a protective film attached to both surfaces of the thin polarizer. The use of resin films is being considered. However, when such a resin film having an extremely low moisture permeability is used as a protective film, deterioration of the polarizer in a humid environment can be suppressed, but a thin polarizer having a thickness of 10 μm or less is used. Moreover, a new problem has been found that a through-crack is generated in the polarizing film even though the protective films are attached to both surfaces of the thin polarizer.

Therefore, in the present invention, in a polarizing film in which a resin film having extremely low moisture permeability is laminated on both surfaces of a polarizer having a thickness of 10 μm or less, deterioration of the polarizer due to humidification is suppressed (humidification reliability), and thermal shock resistance is high. An object of the present invention is to provide a polarizing film capable of suppressing the occurrence of through cracks even in a harsh environment.

As a result of intensive studies to solve the above problems, the present inventors have found the following polarizing film and completed the present invention.

That is, the present invention is a polarizing film having a first resin film on one surface of a polarizer having a thickness of 10 μm or less and a second resin film on the other surface,
The water vapor permeability of each of the first resin film and the second resin film is 30 g/(m ² ·day) or less,
The present invention relates to a polarizing film having a protective plate on a surface of the first resin film opposite to a surface having the polarizer.

The linear expansion coefficient of the protective plate is preferably 1.0×10 ⁻⁵ /K or less in the direction orthogonal to the absorption axis of the polarizer.

The linear expansion coefficient of the first resin film and the second resin film may be 5.0×10 ^{−5 to} 8.0×10 ⁻⁵ /K in the direction orthogonal to the absorption axis of the polarizer. preferable.

The dimensional change rate of the first resin film and the second resin film when heat-treated at 85° C. for 120 hours is −0.40 to 0% in a direction orthogonal to the absorption axis of the polarizer. Is preferred.

The breaking strength of the first resin film and the second resin film is preferably 5 to 30 N in the direction orthogonal to the absorption axis of the polarizer.

The first resin film and the second resin film are preferably the same or different cycloolefin resin films.

85°C, 85% R.I. H. It is preferable that the absolute value of the polarization degree change rate after being left in the environment for 500 hours is less than 0.1%.

The present invention also relates to a polarizing film with a pressure-sensitive adhesive layer, which has a pressure-sensitive adhesive layer on the second resin film side of the polarizing film.

Further, the present invention relates to an image display device having the polarizing film with the pressure-sensitive adhesive layer.

As described above, in a polarizing film in which a resin film having a very low moisture permeability (specifically, 30 g/(m ² ·day) or less) is laminated as a protective film on both surfaces of a thin polarizer, deterioration of the polarizer due to humidification is caused. It was newly found that through cracks occur although it can suppress the heat generation (can improve the humidification reliability). As a factor causing the penetration crack, a resin film (protective film) having an extremely low moisture permeability generally has a large linear expansion coefficient in a direction orthogonal to the absorption axis of the polarizer, a small dimensional change rate, and/ Alternatively, it is considered that the breaking strength is low. In the direction orthogonal to the absorption axis of the polarizer, when the linear expansion coefficient of the protective film is large, the difference between expansion and contraction in the heat shock test becomes large, so that the strain becomes large, and as a result, there is a through crack in the polarizing film. It is thought to occur easily. Further, in the direction orthogonal to the absorption axis of the polarizer, if the dimensional change rate of the protective film is small, it is difficult for the protective film to follow the shrinkage of the polarizer during cooling in the heat shock test, so stress accumulates, and as a result, It is considered that penetration cracks are likely to occur in the polarizing film. Furthermore, if the breaking strength of the protective film is low in the direction orthogonal to the absorption axis of the polarizer, the brittleness of the protective film may trigger the occurrence of through cracks in the polarizing film.

In the present invention, since the protective plate is attached on the first resin film of the polarizing film, it is possible to perform the heat shock test (for example, a heat shock test in which temperature conditions of −40° C. and 85° C. are repeated) under a severe environment. Also, in the direction orthogonal to the absorption axis of the polarizer, since it is possible to reduce the amount of shrinkage as the entire polarizing film, a protective film with extremely low moisture permeability on both sides of the polarizer (in other words, a large linear expansion coefficient Even when a protective film having a small dimensional change rate and/or a low breaking strength is laminated, it is possible to suppress the occurrence of through cracks in the polarizing film. That is, the polarizing film of the present invention can achieve both suppression of deterioration of the polarizer due to humidification (improvement of humidification reliability) and suppression of occurrence of through cracks.

Further, the present invention can provide a pressure-sensitive adhesive layer-attached polarizing film that achieves both improvement of humidification reliability and suppression of penetration crack generation, and an image display device using the pressure-sensitive adhesive layer-attached polarizing film.

It is sectional drawing which shows one Embodiment of the polarizing film of this invention typically. It is sectional drawing which shows typically one Embodiment of the polarizing film with an adhesive layer of this invention.

1. Polarizing Film The polarizing film of the present invention has a first resin film on one surface and a second resin film on the other surface of a polarizer having a thickness of 10 μm or less,
The water vapor permeability of each of the first resin film and the second resin film is 30 g/(m ² ·day) or less,
A protective plate is provided on the surface of the first resin film opposite to the side having the polarizer.

In the present invention, as described above, since the protective plate is attached on the first resin film of the polarizing film, it is harsh against thermal shock (for example, a heat shock test in which temperature conditions of −40° C. and 85° C. are repeated). Even in a humid environment or in a humid environment, it is possible to reduce the amount of shrinkage of the polarizing film as a whole in the direction orthogonal to the absorption axis of the polarizer, and as a result, protect both sides of the polarizer from low moisture permeability. Even if the films are laminated, it is possible to suppress the occurrence of through cracks in the polarizing film.

The structure of the polarizing film of the present invention will be described in detail with reference to FIG. It should be noted that the dimensions of each component in FIG. 1 are examples thereof, and the present invention is not limited to this.

As shown in FIG. 1, the polarizing film 1 of the present invention has a first resin film 3 on one surface of a polarizer 2 and a second resin film 4 on the other surface. Further, the protective plate 5 is provided on the side of the first resin film 3 on which the polarizer 2 is not provided. The first resin film 3 and the second resin film 4 can be attached to the polarizer 2 via an adhesive layer (not shown). The protective plate 5 can via an adhesive layer or a pressure-sensitive Chakuzaiso (not shown) bonded to the first resin film 3. Further, the polarizing film 1 of the present invention can include layers other than the above layers (for example, an easily adhesive layer, various functional layers, etc.).

Further, the first resin film 3 is preferably arranged on the viewing side of the polarizer 2, and the second resin film 4 is preferably arranged on the image display cell side of the polarizer 2.

Hereinafter, each component will be described.

(1) Polarizer In the present invention, a thin polarizer having a thickness of 10 μm or less is used. The thickness of the polarizer is preferably 8 μm or less, more preferably 7 μm or less, and further preferably 6 μm or less from the viewpoint of thinning and suppressing the occurrence of through cracks. On the other hand, the thickness of the polarizer is preferably 2 μm or more, more preferably 3 μm or more. Such a thin polarizer has little thickness unevenness and excellent visibility, and since it has little dimensional change, it has excellent durability against thermal shock.

A polarizer using a polyvinyl alcohol resin is used as the polarizer. Examples of the polarizer include hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene/vinyl acetate copolymer partially saponified films, and dichroic dyes such as iodine and dichroic dyes. Examples include polyene oriented films such as those obtained by adsorbing substances and uniaxially stretched, polyvinyl alcohol dehydrated products, polyvinyl chloride dehydrochlorinated products, and the like. Among these, a polarizer made of a polyvinyl alcohol film and a dichroic substance such as iodine is preferable.

A polarizer obtained by dyeing a polyvinyl alcohol-based film with iodine and uniaxially stretching can be produced, for example, by dyeing polyvinyl alcohol by immersing it in an aqueous solution of iodine and stretching it to 3 to 7 times its original length. If necessary, boric acid, zinc sulfate, zinc chloride or the like may be contained, or the solution may be immersed in an aqueous solution of potassium iodide or the like. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed with water before dyeing. By washing the polyvinyl alcohol-based film with water, it is possible to wash the stains and anti-blocking agents on the surface of the polyvinyl alcohol-based film, and by swelling the polyvinyl alcohol-based film, the effect of preventing unevenness such as uneven dyeing is also provided. is there. Stretching may be performed after dyeing with iodine, stretching while dyeing, or stretching and then dyeing with iodine. Stretching can be carried out in an aqueous solution of boric acid or potassium iodide or in a water bath.

The polarizer preferably contains boric acid from the viewpoint of stretching stability and humidification reliability. In addition, the content of boric acid contained in the polarizer is preferably 22% by weight or less, and more preferably 20% by weight or less, based on the total amount of the polarizer, from the viewpoint of suppressing the occurrence of through cracks. From the viewpoint of stretching stability and humidification reliability, the boric acid content is preferably 10% by weight or more, and more preferably 12% by weight or more, based on the total amount of the polarizer.

As a thin polarizer, typically,
Patent No. 4751486 specification,
Japanese Patent No. 4751481,
Japanese Patent No. 4815544,
Japanese Patent No. 5048120,
International Publication 2014/0775599 pamphlet,
International Publication 2014/077636 pamphlet,
And the thin polarizers obtained by the production methods described therein.

As the thin polarizer, even in a manufacturing method including a step of stretching and a step of dyeing in the state of a laminated body, in that it can be stretched at a high magnification and the polarization performance can be improved, Japanese Patent No. 4751486 Specification, Patent Those obtained by a production method including a step of stretching in an aqueous solution of boric acid as described in Japanese Patent No. 4751481 and Japanese Patent No. 4815544 are preferable, and particularly, those described in Japanese Patent Nos. 4751481 and 4815544 are described. What is obtained by a production method including a step of auxiliary stretching in air before stretching in a boric acid aqueous solution having a certain amount is preferable. These thin polarizer, the polyvinyl alcohol-based resin (hereinafter, also referred to as PVA-based resin) layer and the stretched resin base material can be obtained Ri by the method comprising the step of dyeing the step of stretching in the state of the stack. According to this production method, even if the PVA-based resin layer is thin, it can be stretched without trouble such as breakage due to stretching because it is supported by the stretching resin base material.

(2) First resin film As a material for forming the first resin film provided on one surface of the polarizer, it is transparent and the water vapor transmission rate is 30 g/(m ² ·day) or less. Any material can be used as long as it can form a film. Specifically, for example, a cycloolefin resin film or the like can be used.

As the cycloolefin-based resin film, known ones can be used without particular limitation as long as the moisture permeability is 30 g/(m ² ·day) or less. The cycloolefin-based resin is a general term for resins polymerized with cycloolefin as a polymerized unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137 and the like. Resin. Specific examples thereof include ring-opening (co)polymers of cycloolefins, addition polymers of cycloolefins, copolymers of cycloolefins with α-olefins such as ethylene and propylene (typically random copolymers), Examples thereof include graft polymers obtained by modifying these with unsaturated carboxylic acids and their derivatives, and hydrides thereof. Specific examples of cycloolefins include norbornene-based monomers.

Various products are commercially available as cycloolefin resins. As specific examples, product names “Zonex” and “Zeonor” manufactured by Nippon Zeon Co., Ltd., product names “Arton” manufactured by JSR Co., Ltd., product names “Topas” manufactured by TICONA, manufactured by Mitsui Chemicals, Inc. Trade name “APEL” and the like.

The water vapor permeability of the first resin film is 30 g/(m ² ·day) or less, preferably 25 g/(m ² ·day) or less, and 20 g/(m ² ·day) or less. More preferable. The lower limit of the water vapor transmission rate is not particularly limited, but ideally, it is preferable that no water vapor permeate (that is, 0 g/(m ² ·day)). When the moisture permeability of the first resin film is within the above range, deterioration of the polarizer due to water can be suppressed.

The thickness of the first resin film is not particularly limited, but is 10 μm or more from the viewpoint of lowering the moisture permeability to enhance the humidification reliability and the fracture strength to further suppress the through cracks. The thickness is preferably 12 μm or more, more preferably 12 μm or more. On the other hand, from the viewpoint of thinning, it is preferably 40 μm or less, and more preferably 30 μm or less.

The linear expansion coefficient of the first resin film is not particularly limited, but, for example, in the direction orthogonal to the absorption axis of the polarizer, 5.0×10 ^{−5 to} 8.0×10 ⁻⁵ / For example, K may be about 5.5×10 ^{−5 to} 7.5×10 ⁻⁵ /K. The polarizing film of the present invention can suppress the occurrence of penetrating cracks even when the first resin film having extremely low moisture permeability and a linear expansion coefficient within the above range is used. The linear expansion coefficient can be measured by the measuring method described in the examples.

Further, the breaking strength of the first resin film is not particularly limited, but for example, in the direction orthogonal to the absorption axis of the polarizer, about 5 to 30 N can be mentioned, and about 8 to 25 N. It may be present, or may be about 8 to 23N. The polarizing film of the present invention can suppress the occurrence of penetrating cracks even when the first resin film having extremely low moisture permeability and a breaking strength in the above range is used. The breaking strength can be measured by the measuring method described in the examples.

Further, the dimensional change rate when the first resin film is heat-treated at 85° C. for 120 hours is not particularly limited, but for example, in the direction orthogonal to the absorption axis of the polarizer, −0. It may be about 40 to 0%, may be about -0.34 to 0%, or may be about -0.33 to -0.01%. INDUSTRIAL APPLICABILITY The polarizing film of the present invention can suppress the occurrence of penetrating cracks even when the first resin film having extremely low moisture permeability and a dimensional change rate within the above range is used. The dimensional change rate can be measured by the measuring method described in the examples.

From the viewpoint of humidification reliability, the polarizer and the first resin film are usually adhered to each other via an adhesive such as an active energy ray-curable adhesive. The active energy ray-curable adhesive is an adhesive that is cured by active energy rays such as electron beams and ultraviolet rays (radical curable type, cation curable type), and is, for example, an electron beam curable type or an ultraviolet ray curable type. Can be used. As the active energy ray curable adhesive, for example, a photo radical curable adhesive can be used. When the photoradical curable active energy ray curable adhesive is used as an ultraviolet curable adhesive, the adhesive contains a radical polymerizable compound and a photopolymerization initiator. The coating method of the adhesive is appropriately selected depending on the viscosity of the adhesive and the desired thickness. Examples of the coating method include a reverse coater, a gravure coater (direct, reverse or offset), a bar reverse coater, a roll coater, a die coater, a bar coater, a rod coater and the like. In addition, a method such as a dipping method can be appropriately used for coating.

The surface of the first resin film to which the polarizer is not adhered may be subjected to a hard coat layer, an antireflection treatment, a sticking prevention treatment, or a treatment for the purpose of diffusion or antiglare.

(3) Second resin film A second resin film is provided on the surface of the polarizer opposite to the surface on which the first resin film is formed. The material for forming the second resin film may be any material that is transparent and that can form a film having a water vapor transmission rate of 30 g/(m ² ·day) or less. Specifically, for example, a cycloolefin resin film or the like can be used.

Examples of the cycloolefin-based resin film include those mentioned in the first resin film.

The water vapor transmission rate of the second resin film is 30 g/(m ² ·day) or less, preferably 25 g/(m ² ·day) or less, and 20 g/(m ² ·day) or less. More preferable. The lower limit of the water vapor transmission rate is not particularly limited, but ideally, it is preferable that no water vapor permeate (that is, 0 g/(m ² ·day)). When the moisture permeability of the second resin film is within the above range, deterioration of the polarizer due to water can be suppressed.

The thickness of the second resin film is not particularly limited, but is 10 μm or more from the viewpoint of lowering moisture permeability to improve humidification reliability and fracture strength to further suppress penetration cracks. The thickness is preferably 12 μm or more, more preferably 12 μm or more. On the other hand, from the viewpoint of thinning, it is preferably 40 μm or less, and more preferably 30 μm or less.

The linear expansion coefficient of the second resin film is not particularly limited, but, for example, in the direction orthogonal to the absorption axis of the polarizer, 5.0×10 ^{−5 to} 8.0×10 ⁻⁵ / For example, K may be about 5.5×10 ^{−5 to} 7.5×10 ⁻⁵ /K. The polarizing film of the present invention can suppress the occurrence of through cracks even when the second resin film having extremely low moisture permeability and a linear expansion coefficient within the above range is used. The linear expansion coefficient can be measured by the measuring method described in the examples.

Moreover, the breaking strength of the second resin film is not particularly limited, but for example, in the direction orthogonal to the absorption axis of the polarizer, about 5 to 30 N can be mentioned, and about 8 to 25 N. It may be present, or may be about 8 to 23N. The polarizing film of the present invention can suppress the occurrence of penetrating cracks even when the second resin film having extremely low moisture permeability and breaking strength in the above range is used. The breaking strength can be measured by the measuring method described in the examples.

Further, the dimensional change rate when the second resin film is heat-treated at 85° C. for 120 hours is not particularly limited, but, for example, in the direction orthogonal to the absorption axis of the polarizer, −0. It may be about 40 to 0%, may be about -0.34 to 0%, or may be about -0.33 to -0.01%. The polarizing film of the present invention can suppress the occurrence of through cracks even when the second resin film having extremely low moisture permeability and a dimensional change rate within the above range is used. The dimensional change rate can be measured by the measuring method described in the examples.

The polarizer and the second resin film are usually in close contact with each other via an adhesive. Examples of the adhesive include those listed for the first resin film.

The surface of the second resin film to which the polarizer is not adhered may be subjected to a treatment for the purpose of hard coat layer, antireflection treatment, sticking prevention, diffusion or antiglare.

(4) Protective Plate The polarizing film of the present invention has a protective plate on the side of the first resin film that does not have the polarizer. By providing the protective plate, the amount of shrinkage of the polarizer during the heat shock test can be suppressed, so that the occurrence of through cracks can be suppressed.

The protective plate is not particularly limited as long as it can suppress the shrinkage of the polarizing film even when the polarizing film of the present invention is exposed to a thermal shock environment.

The linear expansion coefficient of the protective plate is preferably 1.0×10 ⁻⁵ /K or less, and 9.0×10 ⁻⁶ /K or less in the direction orthogonal to the absorption axis of the polarizer. Is more preferable, and it is further preferable that it is 8.0×10 ⁻⁶ /K or less. In the direction orthogonal to the absorption axis of the polarizer, when the linear expansion coefficient of the protective plate is in the above range, in the heat shock test, the protective plate can suppress the shrinkage amount of the polarizer, the through cracks. The occurrence can be suppressed more effectively. Further, the lower limit of the linear expansion coefficient is not particularly limited, but is preferably 1.0×10 ⁻⁶ /K or more, for example.

The thickness of the protective plate is not particularly limited, but is preferably 0.5 to 1.0 mm, more preferably 0.5 to 0.8 mm. When the thickness of the protective plate is within the above range, dimensional shrinkage is less likely to occur, which is preferable.

The pencil hardness of the protective plate is preferably 8H or more, more preferably 10H or more. It is preferable that the pencil hardness of the protective plate is within the above range, because it is difficult for the dimension to shrink. The pencil hardness is a pencil hardness according to JIS K 5600-5-4.

The specific gravity of the protective plate is preferably 2.0 or more, more preferably 2.3 or more. It is preferable for the specific gravity of the protective plate to be within the above range, because it is difficult for the dimension to shrink.

The thermal conductivity of the protective plate is preferably 2.0 W/(m·K) or less, and more preferably 1.5 W/(m·K) or less. Since the heat conductivity of the protective plate is in the above range, heat is difficult to be transmitted to the polarizer even in the heat shock test, and the shrinkage amount of the polarizer can be suppressed in the direction orthogonal to the absorption axis of the polarizer. Therefore, it is preferable.

The material for forming the protective plate is not particularly limited, and examples thereof include glass and acrylic plates. Of these, glass is preferable.

The protective plate and the first resin film can be laminated via an adhesive layer or a pressure-sensitive adhesive layer. As the adhesive layer, the adhesive layer described in this specification can be appropriately used.

The pressure-sensitive adhesive layer is not particularly limited, and known materials can be used. As such an adhesive layer, specifically, for example, a (meth)acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer is used as a base polymer. Can be appropriately selected and used. Among these, acrylic pressure-sensitive adhesives based on (meth)acrylic polymers are excellent in optical transparency and show appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and have weather resistance and heat resistance. It is preferable because it has excellent properties.

The (meth)acrylic polymer is not particularly limited, but is obtained by polymerizing a monomer component containing an alkyl(meth)acrylate having an alkyl group having 4 to 24 carbon atoms at the end of an ester group. You can list the ones. In addition, alkyl (meth)acrylate means alkyl acrylate and/or alkyl methacrylate, and has the same meaning as (meth) of the present invention.

Examples of the alkyl (meth)acrylate include those having a linear or branched alkyl group having 4 to 24 carbon atoms, and having a linear or branched alkyl group having 4 to 9 carbon atoms. Alkyl (meth)acrylate is preferable because it is easy to balance the adhesive properties. These alkyl (meth)acrylates may be used alone or in combination of two or more.

The monomer component forming the (meth)acrylic polymer may contain, as a monofunctional monomer component, a copolymerization monomer other than the alkyl (meth)acrylate. Examples of such a copolymerization monomer include a cyclic nitrogen-containing monomer, a hydroxyl group-containing monomer, a carboxyl group-containing monomer, and a monomer having a cyclic ether group.

In addition to the monofunctional monomer, the monomer component forming the (meth)acrylic polymer may contain a polyfunctional monomer in order to adjust the cohesive force of the pressure-sensitive adhesive. .. The polyfunctional monomer is a monomer having at least two polymerizable functional groups having an unsaturated double bond such as a (meth)acryloyl group or a vinyl group, and for example, dipentaerythritol hexa(meth)acrylate, 1 , 6-hexanediol di(meth)acrylate and trimethylolpropane tri(meth)acrylate. The polyfunctional monomers may be used alone or in combination of two or more.

For the production of such a (meth)acrylic polymer, a known production method such as solution polymerization, radiation polymerization such as ultraviolet polymerization, bulk polymerization, and various radical polymerization such as emulsion polymerization can be appropriately selected. Further, the obtained (meth)acrylic polymer may be any of a random copolymer, a block copolymer, a graft copolymer and the like.

The polymerization initiator, chain transfer agent, emulsifier, etc. used in the radical polymerization are not particularly limited, and known ones commonly used in this field can be appropriately selected and used. Further, the weight average molecular weight of the (meth)acrylic polymer can be controlled by the amount of the polymerization initiator and the chain transfer agent used and the reaction conditions, and the amount used is appropriately adjusted according to these types.

The weight average molecular weight of the (meth)acrylic polymer used in the present invention is preferably 400,000 to 4,000,000. By setting the weight average molecular weight to be more than 400,000, it is possible to satisfy the durability of the pressure-sensitive adhesive layer and to suppress the adhesive residue from causing the adhesive force to be reduced to cause adhesive residue. On the other hand, when the weight average molecular weight is more than 4,000,000, the bondability tends to deteriorate. Further, the viscosity of the pressure-sensitive adhesive in a solution system becomes too high, which may make coating difficult. The weight average molecular weight was measured by GPC (Gerupami et Shon chromatography) refers to a value calculated in terms of polystyrene. The molecular weight of the (meth)acrylic polymer obtained by radiation polymerization is difficult to measure.

The pressure-sensitive adhesive composition used in the present invention may contain a crosslinking agent. As the crosslinking agent, an isocyanate crosslinking agent, an epoxy crosslinking agent, a silicone crosslinking agent, an oxazoline crosslinking agent, an aziridine crosslinking agent, a silane crosslinking agent, an alkyl etherified melamine crosslinking agent, a metal chelate crosslinking agent, a peroxide. Examples thereof include crosslinking agents such as oxides, which may be used alone or in combination of two or more. As the crosslinking agent, an isocyanate crosslinking agent and an epoxy crosslinking agent are preferably used.

The cross-linking agent may be used alone, or two or more kinds may be mixed and used, but the content as a whole is based on 100 parts by weight of the (meth)acrylic polymer. It is preferable to contain the cross-linking agent in the range of 0.01 to 10 parts by weight.

The pressure-sensitive adhesive composition used in the present invention may contain a (meth)acrylic oligomer in order to improve the adhesive strength. Further, the pressure-sensitive adhesive composition used in the present invention may contain a silane coupling agent in order to enhance water resistance at the interface when applied to a hydrophilic adherend such as glass of the pressure-sensitive adhesive layer.

Further, the pressure-sensitive adhesive composition used in the present invention may contain other known additives, for example, polyether compounds of polyalkylene glycol such as polypropylene glycol, colorants, powders such as pigments, dyes. , Surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, softeners, antioxidants, antioxidants, light stabilizers, UV absorbers, polymerization inhibitors, inorganic or organic fillers, Metal powder, particulates, foils and the like can be appropriately added depending on the intended use. Further, a redox system to which a reducing agent is added may be adopted within a controllable range.

The pressure-sensitive adhesive layer can be formed by a known method.

Further, as a pressure-sensitive adhesive layer for laminating the protective plate and the first resin film, “LUCIACS” manufactured by Nitto Denko Corporation, “Clear Fit” manufactured by Mitsubishi Plastics Co., Ltd., manufactured by Dexerials Co., Ltd. Commercially available products such as an adhesive layer (adhesive sheet) such as "optical elastic resin (SVR)" can also be preferably used.

The polarizing film of the present invention has an R. H. The absolute value of the polarization rate change rate after standing for 500 hours in the environment is preferably less than 0.1%, more preferably 0.05% or less, and further preferably 0.03% or less. preferable. Polarizing film of the present invention, since the bonding a protective plate on the first resin film, thermal shock (e.g., heat shock test to repeat a temperature of -40 ℃ and 85 ° C.) Oite the harsh environment of In addition, the shrinkage force of the polarizing film as a whole is extremely small, and since the low moisture permeability protective film is used, deterioration of the polarizer due to water is suppressed, and as a result, even if it is exposed to a harsh environment, The degree of change is small and the optical characteristics are excellent.

2. Polarizing Film with Adhesive Layer The polarizing film with an adhesive layer of the present invention has an adhesive layer on the second resin film side of the polarizing film.

The pressure-sensitive adhesive layer can be laminated on the side of the second resin film having no polarizer. Specifically, as shown in FIG. 2, the pressure-sensitive adhesive layer-attached polarizing film 10 of the present invention comprises a protective plate 5, a first resin film 3, a polarizer 2, a second resin film 4, and an adhesive layer 6. Have in order.

The pressure-sensitive adhesive layer-attached polarizing film of the present invention is formed by directly applying the pressure-sensitive adhesive composition on the second resin film of the polarizing film having the protective plate, and removing the solvent or the like by heating and drying to form the pressure-sensitive adhesive layer. Can be formed. Further, the pressure-sensitive adhesive layer formed on the support or the like can be transferred onto the second resin film of the polarizing film to form a pressure-sensitive adhesive layer-attached polarizing film.

As the pressure-sensitive adhesive composition, those described in the present specification can be appropriately used, but among them, an acrylic pressure-sensitive adhesive using the above-mentioned (meth)acrylic polymer as a base polymer is preferable.

Various methods are used as a method for applying the pressure-sensitive adhesive composition. Specifically, for example, roll coat, kiss roll coat, gravure coat, reverse coat, roll brush, spray coat, dip roll coat, bar coat, knife coat, air knife coat, curtain coat, lip coat, die coater, etc. Examples of the method include an extrusion coating method.

The heating and drying temperature is preferably about 30 to 200°C, more preferably about 40 to 180°C, and even more preferably about 80 to 150°C. By setting the heating temperature in the above range, a pressure-sensitive adhesive layer having excellent pressure-sensitive adhesive properties can be obtained. As the drying time, an appropriate time can be appropriately adopted. The drying time is preferably about 5 seconds to 20 minutes, more preferably about 30 seconds to 10 minutes, and even more preferably 1 minute to 8 minutes.

As the support, for example, a release-treated sheet (separator) can be used. A silicone release liner is preferably used as the release-treated sheet.

As the constituent material of the separator, for example, polyethylene, polypropylene, polyethylene terephthalate, a plastic film such as a polyester film, a porous material such as paper, cloth, non-woven fabric, a net, a foamed sheet, a metal foil, and a laminated body thereof are appropriately used. Examples thereof include thin leaf bodies, but plastic films are preferably used because of their excellent surface smoothness.

Examples of the plastic film include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene. -Vinyl acetate copolymer film and the like can be mentioned.

The thickness of the separator is usually 5 to 200 μm, preferably about 5 to 100 μm. In the separator, if necessary, a silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agent, release with silica powder, and antifouling treatment, coating type, kneading type, vapor deposition Antistatic treatment of a mold or the like can also be performed. In particular, by appropriately performing a peeling treatment such as a silicone treatment, a long-chain alkyl treatment, or a fluorine treatment on the surface of the separator, the peelability from the pressure-sensitive adhesive layer can be further enhanced.

The release-treated sheet used in the production of the pressure-sensitive adhesive layer-carrying polarizing film can be used as it is as a separator for the pressure-sensitive adhesive layer-carrying polarizing film, and the process can be simplified.

Further, in forming the pressure-sensitive adhesive layer in the above-mentioned pressure-sensitive adhesive layer-attached polarizing film, an adhesive layer is formed on the surface of the second resin film after various anchor adhesion treatments, corona treatments, plasma treatments and the like. An agent layer can be formed. Further, the surface of the pressure-sensitive adhesive layer may be subjected to easy adhesion treatment.

The thickness of the pressure-sensitive adhesive layer is not particularly limited and is, for example, preferably 5 to 100 μm, and more preferably 10 to 50 μm.

The pressure-sensitive adhesive layer-attached polarizing film of the present invention uses a double-sided protective polarization film having a polarizer thickness of 10 μm or less, so that the pressure-sensitive adhesive layer-attached polarizing film as a whole can be thinned. The thickness of the polarizing film with the pressure-sensitive adhesive layer can be 70 μm or less.

The polarizing film with a pressure-sensitive adhesive layer of the present invention can be attached to an image display cell such as a liquid crystal cell via the pressure-sensitive adhesive layer. In particular, the pressure-sensitive adhesive layer-attached polarizing film of the present invention can be suitably used as a viewing side polarizing film of a liquid crystal display device.

3. Image Display Device The image display device of the present invention has the polarizing film with the pressure-sensitive adhesive layer.

The image display device of the present invention may be any one as long as it includes the pressure-sensitive adhesive layer-attached polarizing film of the present invention, and other configurations include the same as those of conventional image display devices.

Since the image display device of the present invention includes the polarizing film with the pressure-sensitive adhesive layer, it has high reliability.

The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. The parts and% in each example are based on weight.

Production Example 1 (Production of Polarizing Film (1))
Amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 μm) having a water absorption of 0.75% and a Tg of 75° C. was corona-treated on one side of the base material, and the corona-treated surface was treated with polyvinyl chloride. Alcohol (degree of polymerization: 4200, degree of saponification: 99.2 mol%) and acetoacetyl-modified PVA (degree of polymerization: 1200, degree of acetoacetyl modification: 4.6%, degree of saponification: 99.0 mol% or more, Japan Synthetic Chemical Industry Co., Ltd., trade name "Gosephimmer Z200") is applied at 25°C and an aqueous solution containing 9:1 ratio is applied and dried to form a PVA-based resin layer having a thickness of 11 µm. It was made.
The obtained laminated body was uniaxially stretched by 2.0 times in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds in an oven at 120° C. (in-air auxiliary stretching treatment).
Then, the laminated body was immersed in an insolubilizing bath having a liquid temperature of 30° C. (boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) for 30 seconds (insolubilization treatment).
Then, the polarizing plate was immersed in a dyeing bath having a liquid temperature of 30° C. while adjusting the iodine concentration and the immersion time so that the polarizing plate had a predetermined transmittance. In this example, 0.2 part by weight of iodine was added to 100 parts by weight of water, and 1.0 part by weight of potassium iodide was added, and the resultant was immersed for 60 seconds in an aqueous iodine solution (dyeing treatment). ..
Then, it was immersed for 30 seconds in a crosslinking bath at a liquid temperature of 30° C. (an aqueous boric acid solution obtained by mixing 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with 100 parts by weight of water). (Crosslinking treatment).
Then, the laminated body was added to an aqueous boric acid solution having a liquid temperature of 70° C. (an aqueous solution obtained by adding 4.5 parts by weight of boric acid and 5 parts by weight of potassium iodide to 100 parts by weight of water). While being immersed, uniaxial stretching was performed between rolls having different peripheral speeds in the longitudinal direction (longitudinal direction) such that the total stretching ratio was 5.5 (underwater stretching treatment).
After that, the laminate was immersed in a cleaning bath having a liquid temperature of 30° C. (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 100 parts by weight of water) (cleaning treatment).
As described above, an optical film laminate including a polarizer having a thickness of 5 μm was obtained. The boric acid content of the obtained polarizer was 20% by weight.

(Preparation of adhesive applied to transparent protective film)
40 parts by weight of N-hydroxyethylacrylamide (HEAA), 60 parts by weight of acryloylmorpholine (ACMO) and 3 parts by weight of a photoinitiator "IRGACURE 819" (manufactured by BASF) were mixed to prepare an ultraviolet curable adhesive.

The visible side transparent protective film while applying the ultraviolet curable adhesive to the surface of the polarizer (thickness: 5 μm) of the optical film laminate so that the adhesive layer after curing has a thickness of 0.1 μm. (First resin film) (27 μm thick cycloolefin film (trade name: ZF12-025-1300UHC, manufactured by Nippon Zeon Co., Ltd.), moisture permeability at 40° C., 92% RH: 17 g/(m ² ·day), linear expansion coefficient: 6×10 ⁻⁵ /K, dimensional change rate: −0.33%, breaking strength: 13 N), and then radiated with ultraviolet rays as active energy rays to obtain an adhesive. Was cured. Ultraviolet irradiation is performed using a gallium-encapsulated metal halide lamp, irradiation device: Fusion UV Systems, Inc. Light HAMMER10, bulb: V bulb, peak illuminance: 1600 mW/cm ² , integrated irradiation amount 1000/mJ/cm ² (wavelength 380 to 440 nm). ) Was used, and the illuminance of ultraviolet rays was measured using a Sola-Check system manufactured by Solatell. Then, the amorphous PET base material is peeled off, and the UV-ray-curable adhesive is applied to the peeled surface so that the thickness of the adhesive layer after curing becomes 0.1 μm, and the corona treatment is performed in advance. Image display cell side transparent protective film (second resin film) (thickness 13 μm of cycloolefin film (trade name: ZF-014-1330, manufactured by Nippon Zeon Co., Ltd.), 40° C., 92% RH. Moisture permeability: 12 g/(m ² ·day), linear expansion coefficient: 7.1×10 ⁻⁵ /K, dimensional change rate: −0.01%, breaking strength: 9 N), and then bond as above. Similarly, ultraviolet rays were irradiated to cure the adhesive, and a double-sided protective polarizing film (1) using a thin polarizer was produced.

Production Example 2 (Production of Polarizing Film (2))
On the surface of the polarizer (thickness: 5 μm) of the optical film laminate obtained in Production Example 1, the thickness of the adhesive layer after curing the ultraviolet curable adhesive produced in Example 1 is 0.1 μm. While coating as described above, a transparent protective film on the visual side (a cycloolefin film having a thickness of 27 μm (trade name: ZD12-099063-C1300UHC, manufactured by Nippon Zeon Co., Ltd.), 40° C., 92% RH moisture permeability : 24 g/(m ² ·day), linear expansion coefficient: 6.3×10 ⁻⁵ /K, dimensional change rate: −0.28%, breaking strength: 20 N), and then as an active energy ray, Ultraviolet rays were irradiated to cure the adhesive. Ultraviolet irradiation is performed using a gallium-encapsulated metal halide lamp, irradiation device: Fusion UV Systems, Inc. Light HAMMER10, bulb: V bulb, peak illuminance: 1600 mW/cm ² , integrated irradiation amount 1000/mJ/cm ² (wavelength 380 to 440 nm). ) Was used, and the illuminance of ultraviolet rays was measured using a Sola-Check system manufactured by Solatell. Then, the amorphous PET substrate was peeled off, and the ultraviolet curable adhesive produced in Example 1 was applied to the peeled surface so that the thickness of the cured adhesive layer would be 0.1 μm. , Transparent protective film on the image display cell side (a cycloolefin film having a thickness of 13 μm (trade name: ZF-014-130, manufactured by Nippon Zeon Co., Ltd.), moisture permeability at 40° C., 92% RH: 12 g/ (M ² ·day), linear expansion coefficient: 7.1×10 ⁻⁵ /K, dimensional change rate: −0.01%, breaking strength: 9N), and then UV irradiation is performed in the same manner as above. The adhesive was cured to prepare a double-sided protective polarizing film (2) using a thin polarizer.

Production Example 3 (Production of Polarizing Film (3))
While the polyvinyl alcohol adhesive was applied to the surface of the polarizer (thickness: 5 μm) of the optical film laminate obtained in Production Example 1 so that the adhesive layer had a thickness of 0.1 μm, the visible side was transparent. Protective film (40 μm thick acrylic film (trade name: HX-40UC-1330, manufactured by Kaneka Corporation), moisture permeability at 40° C., 92% RH: 70 g/(m ² ·day), line An expansion coefficient of 4.3×10 ⁻⁵ /K, a dimensional change rate of −0.5%, and a breaking strength of 39 N) were laminated, and then dried at 50° C. for 5 minutes. Then, the amorphous PET substrate was peeled off, and a polyvinyl alcohol-based adhesive was applied to the peeled surface so that the adhesive layer had a thickness of 0.1 μm, while the image display cell side transparent protective film ( 20 μm thick acrylic film (trade name: RV-20UB-1330, manufactured by Toyo Kohan Co., Ltd.), water vapor permeability at 40° C., 92% RH: 170 g/(m ² ·day), linear expansion Coefficient: 5.6×10 ⁻⁵ /K, dimensional change rate: −0.35%, breaking strength: 19N), and then drying at 50° C. for 5 minutes, and using a thin polarizer on both sides. A protective polarizing film (3) was produced.

Example 1
On the viewing side protective film of the double-sided protective polarizing film (1) obtained in Production Example 1, an adhesive sheet (thickness: 150 μm, “LUCIACS” (trade name) which is an adhesive sheet manufactured by Nitto Denko Corporation). To form a pressure-sensitive adhesive layer, and a protective plate (cover glass having a thickness of 500 μm, linear expansion coefficient: 8×10 ⁻⁶ /K, pencil hardness: 10H, specific gravity: 2.5, on the pressure-sensitive adhesive layer. Thermal conductivity: 1 W/(m·K)) was laminated to form a polarizing film with a protective plate.

Example 2
A polarizing plate with a protective plate was formed in the same manner as in Example 1 except that the double-sided protective polarizing film (2) obtained in Production Example 2 was used.

Comparative Examples 1-3
In Comparative Examples 1 to 3, the double-sided protective polarizing films (1) to (3) obtained in Production Examples 1 to 3 were used as they were (without protective plate lamination).

Examples, moisture permeability of the protective film used in Comparative Examples, the linear expansion coefficient of the protective film and the protective plate, the polarizing film with the protective film obtained in Examples, the dimensional change rate of the polarizing film used in Comparative Examples, and penetration The occurrence of cracks was measured by the following method.

<Water vapor permeability of transparent protective film>
The moisture permeability was measured according to the moisture permeability test (cup method) of JIS Z0208. The sample cut into a diameter of 6 cm was set in a moisture permeable cup (opening diameter: diameter 6 cm) containing about 15 g of calcium chloride, and the temperature was 40° C. and the humidity was 92% R.V. H. The moisture permeability (g/(m ² ·day) was determined by measuring the weight increase of calcium chloride before and after leaving it in the incubator for 24 hours.

<Dimensional change rate>
Samples were prepared by cutting the double-sided protective polarizing film used in the examples and comparative examples to a size of 100 mm×100 mm (polarizer absorption axis direction was 100 mm). The sample was autoclaved at 50° C. and 0.5 MPa for 15 minutes, taken out from the autoclave, and left in an environment of room temperature (23° C.) for 24 hours. Then, it put into the 85 degreeC oven for 120 hours. After taking out from the oven, the protective film was peeled off from the sample, and the length of each protective film was measured using a non-contact type two-dimensional image analyzer (trade name: QVA606L1L-C, manufactured by Mitutoyo Co., Ltd.). Was measured. The dimensional change rate was calculated based on the following formula from the measured values before and after the treatment.
Dimensional change rate (%)={(L ₀ −L ₁ )/L ₁ }×100
L ₀ : length of the initial protective film in the direction orthogonal to the absorption axis of the polarizer (100 mm)
L ₁ : length of the protective film after being left in a heating environment in a direction orthogonal to the absorption axis of the polarizer

<Measurement of linear expansion coefficient>
The linear expansion coefficient was measured using a thermomechanical analyzer (product name: TMA7100, manufactured by Hitachi High-Tech Science Co., Ltd.). Specifically, a sample (length 20 mm×width 5 mm) is cut out from the protective film or protective plate used in Examples and Comparative Examples, the sample is set in a tensile measurement jig, and the tensile load is 20 mN, the temperature rising rate, A linear expansion coefficient was obtained by measuring 10°C/min and -40°C to 85°C under the condition of 4 cycles (heat shock condition). The linear expansion coefficient was measured in the direction orthogonal to the absorption axis of the polarizer.

<Measurement of breaking strength>
After cutting the protective film used in Examples and Comparative Examples into 100 mm×100 mm, an autograph (product name: AG-IS, manufactured by Shimadzu Corporation) was used as a tensile tester, and the test sample was pulled. A tensile test was performed at a speed of 300 mm/min, a chuck distance of 100 mm, and room temperature (23° C.) to obtain a stress-strain curve. The stress when the protective film broke was determined and defined as the breaking strength. The breaking strength was measured in the direction orthogonal to the absorption axis of the polarizer.

<Measurement of polarization degree change (ΔP) of polarizing film>
The polarizing films obtained in the examples and comparative examples were subjected to 85° C./85% R.V. H. It was put in the constant temperature and constant humidity machine for 500 hours. The polarization degree of the polarizing film before and after the addition was measured using a spectrophotometer with an integrating sphere (V7100 manufactured by JASCO Corporation), and the change amount ΔP of the polarization degree was calculated by the following formula.
Amount of change in polarization degree ΔP (%) = (polarization degree before input (%))-(polarization degree after input (%))
The degree of polarization P is the transmissivity (parallel transmissivity: Tp) when two identical polarizing films are superposed so that their transmissive axes are parallel, and the superposition is such that both transmissive axes are orthogonal. It is obtained by applying the transmittance (orthogonal transmittance: Tc) in the combined case to the following formula.
Polarization degree P(%)={(Tp−Tc)/(Tp+Tc)} ^1/2 ×100
Each transmittance is represented by a Y value which is adjusted in terms of visual sensitivity by a 2 degree visual field (C light source) of JIS Z8701, with 100% of the completely polarized light obtained through the Glan-Teller prism polarizer.

<Confirmation of penetration cracks: Heat shock test>
A pressure-sensitive adhesive layer was provided on the transparent protective film side of the image display cell side of the double-sided protective polarizing film obtained in Examples and Comparative Examples to prepare a polarizing film with a pressure-sensitive adhesive layer. The polarizing film with the pressure-sensitive adhesive layer was cut into 50 mm×150 mm (50 mm in the absorption axis direction) and bonded to a 0.5 mm thick non-alkali glass to prepare a sample. After heat-shocking the sample at −40 to 85° C. for 30 minutes in each environment of 100 times, it was taken out and visually confirmed whether a through crack (number) occurred in the polarizing film. .. This test was performed 10 times.

DESCRIPTION OF SYMBOLS 1 Polarizing film 2 Polarizer 3 1st resin film 4 2nd resin film 5 Protective plate 6 Adhesive layer 10 Polarizing film with an adhesive layer

Claims (8)

A polarizing film having a first resin film on one surface and a second resin film on the other surface of a polarizer having a thickness of 10 μm or less,
The water vapor transmission rate of each of the first resin film and the second resin film measured by the following method is 30 g/(m ² ·day) or less,
Wherein the said side having the polarizer of the first resin film have a protective plate on the opposite side,
85°C, 85% R.I. H. Polarizing films absolute value of the polarization degree change ratio after 500 hours left in an environment, characterized in der Rukoto 0.05% or less.
<Water vapor transmission rate>
The moisture permeability is measured according to the moisture permeability test (cup method) of JIS Z0208. The sample cut into a diameter of 6 cm was set in a moisture permeable cup (opening diameter: diameter 6 cm) containing 15 g of calcium chloride, and the temperature was 40° C. and the humidity was 92% R.S. H. The moisture permeability (g/m ² ·day) is determined by measuring the weight increase of calcium chloride before and after leaving it in the incubator for 24 hours . The linear expansion coefficient of the protective plate measured by the following method is 1.0×10 ⁻⁵ /K or less in the direction orthogonal to the absorption axis of the polarizer. Polarizing film.
<Measurement of linear expansion coefficient>
The coefficient of linear expansion is measured using a thermomechanical analyzer. A sample (length 20 mm × width 5 mm) is cut out from the protective plate, the sample is set on a tensile measurement jig, and a tensile load of 20 mN, a temperature rising rate of 10°C/min, and -40°C to 85°C for 4 cycles (heat). (Shock condition) to obtain a linear expansion coefficient. The linear expansion coefficient is measured in the direction orthogonal to the absorption axis of the polarizer. The linear expansion coefficient of the first resin film and the second resin film measured by the following method is 5.0×10 ^{−5 to} 8.0×10 ^{−5 in the} direction orthogonal to the absorption axis of the polarizer. /K, The polarizing film according to claim 1 or 2.
<Measurement of linear expansion coefficient>
The coefficient of linear expansion is measured using a thermomechanical analyzer. A sample (length 20 mm x width 5 mm) is cut out from the first resin film or the second resin film, the sample is set on a tensile measurement jig, and the tensile load is 20 mN, the heating rate is 10°C/min, and -40°C ~ 85° C. is measured under the condition of 4 cycles (heat shock condition) to obtain a linear expansion coefficient. The linear expansion coefficient is measured in the direction orthogonal to the absorption axis of the polarizer. The dimensional change rate of the first resin film and the second resin film when heat-treated at 85° C. for 120 hours is −0.40 to 0% in a direction orthogonal to the absorption axis of the polarizer. The polarizing film according to any one of claims 1 to 3. The breaking strength of the first resin film and the second resin film measured by the following method is 5 to 30 N in a direction orthogonal to the absorption axis of the polarizer. The polarizing film according to any one.
<Measurement of breaking strength>
After cutting the first resin film or the second resin film into 100 mm×100 mm, an autograph was used as a tensile tester, and a test sample was pulled at a pulling speed of 300 mm/min, a chuck distance of 100 mm, and room temperature (23° C.). A tensile test is performed to obtain a stress-strain curve. The stress when the test sample breaks is calculated and used as the breaking strength. The breaking strength is measured in the direction orthogonal to the absorption axis of the polarizer. The said 1st resin film and the said 2nd resin film are the same or different cycloolefin system resin films, The polarizing film in any one of Claims 1-5 characterized by the above-mentioned. Polarizing film with an adhesive layer and having an adhesive layer on the second resin film side of the polarizing film according to any one of claims 1-6. An image display device comprising the polarizing film with an adhesive layer according to claim 7 .

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