TW202001308A - Polarizing film, polarizing film with adhesive layer, and image display device - Google Patents

Abstract

The purpose of the present invention is to provide a polarizing film which is not susceptible to the occurrence of a crack in a polarizer even under severe thermal shock conditions. A polarizing film according to the present invention is obtained by providing one surface or both surfaces of a polarizer with a protective film, with an adhesive layer being interposed therebetween; and at least one protective film provided on the polarizer satisfies formula (1). (1): Y ≤ 1.26 * lnX + 3.5 (In the formula, Y is the linear expansion coefficient (* 10<SP>-5</SP>/K) of the protective film; and X is the elongation (%) at break of the protective film.).

Description

Polarizing film, polarizing film with adhesive layer and image display device

The invention relates to a polarizing film, and a polarizing film having an adhesive layer and an adhesive layer with the polarizing film and the adhesive layer. Moreover, the present invention relates to an image display device including the polarizing film or the polarizing film with an adhesive layer.

Background of the invention In various image display devices, polarizing films are used for displaying images. For example, in view of the image forming method of a liquid crystal display device (LCD), it is necessary to dispose polarizing films on both sides of the glass substrate forming the surface of the liquid crystal panel. On the organic EL display device, in order to shield the specular reflection of the external light on the metal electrode, a circular polarizing film laminated with a polarizing film and a quarter-wave plate is arranged on the viewing side of the organic light emitting layer.

The aforementioned polarizing film is generally used when a polarizing member composed of a polyvinyl alcohol-based film and a dichroic material such as iodine passes through a polyvinyl alcohol-based adhesive or the like and has a protective film laminated on one or both sides.

Under the severe environment of thermal shock (for example, repeated thermal shock tests conducted at -40°C and 85°C), the polarizing film may be easily absorbed in the direction of the absorption axis due to changes in the shrinkage stress of the polarizer The problem of cracks (penetrating cracks) occurs.

Patent Document 1 proposes a polarizing plate with the purpose of providing a polarizing plate that is excellent in durability even under cold and hot shock environments. The polarizing plate is formed by disposing transparent protective films on both sides of the polarizing film, and is characterized by: The difference between the linear expansion coefficient of the polarizing film in a direction orthogonal to the absorption axis and the linear expansion coefficient of the transparent protective film disposed on at least one surface of the polarizing film in a direction orthogonal to the absorption axis of the polarizing plate is 1.3× 10 ^-4 /℃ or less.

Prior technical literature Patent Literature Patent Document 1: Japanese Patent Laid-Open No. 2011-203571

Summary of the invention Problems to be solved by invention However, even the polarizing plate of Patent Document 1, depending on the type of the transparent protective film, the stress of the transparent protective film based on expansion and contraction may still greatly affect the expansion and contraction of the polarizing film, so it may occur in the polarizing film Crack situation.

The object of the present invention is to provide a polarizing film which is not prone to cracking of the polarizer even under severe environment of thermal shock.

Furthermore, an object of the present invention is to provide an adhesive-attached polarizing film having the polarizing film and the adhesive layer, and an image display device including the polarizing film or the adhesive-attached polarizing film.

The method used to solve the problem After an active review by the present inventors, it was found that the above-mentioned problems can be solved by the following polarizing film, and the present invention was completed.

That is, the present invention relates to a polarizing film provided with a protective film on one side or both sides of the polarizing member via an adhesive layer. The polarizing film is characterized by: at least one of the aforementioned protective films provided on the polarizing member Those satisfying the following formula (1): Y≦1.26×lnX+3.5 (1) Y: Coefficient of linear expansion of the protective film (×10 ^-5 /K) X: Breaking elongation (%) of the protective film.

In the polarizing film, the Y (×10 ^-5 /K) is preferably 4 or less.

In the polarizing film, the thickness of the polarizer is preferably 10 μm or less.

In addition, the present invention relates to a polarizing film with an adhesive layer and an adhesive layer.

The present invention also relates to an image display device, wherein the image display unit is provided with the polarizing film or the polarizing film with an adhesive layer.

Invention effect By using at least one protective film that satisfies the aforementioned formula (1) as the protective film provided on one or both sides of the polarizer, the expansion and contraction of the polarizer caused by the stress of the protective film due to expansion and contraction can be alleviated Because of the stress, it is not easy to crack the polarizer.

By using a protective film with a linear expansion coefficient Y (×10 ^-5 /K) of 4 or less, the stress caused by the expansion and contraction of the polarizer can be more effectively relieved, so that the cracks in the polarizer can be more effectively suppressed.

In addition, in recent years, with the development of thinner image display devices such as liquid crystal display devices, polarizers are also required to be thinner. However, a thin polarizer with a thickness of 10 μm or less has a problem that its optical characteristics are easily degraded under a humidified environment (due to moisture). In order to suppress the deterioration of the thin polarizer due to moisture, we considered using a resin film with low moisture permeability (specifically, 100 g/(m ² ·day) or less) as a protective film attached to the thin polarizer. When a resin film with low moisture permeability is used as a protective film, the deterioration of the polarizer under a humidified environment can be suppressed. However, the protective film with low moisture permeability tends to have a large coefficient of linear expansion, and it will be difficult to alleviate the stress caused by the expansion and contraction of the polarizer, so the polarizer is likely to crack. However, even a protective film with a large linear expansion coefficient, as long as the protective film has a large elongation at break and satisfies the above formula (1), it can effectively relieve the stress caused by the expansion and contraction of the polarizer, so it is not easy to crack the polarizer. . Therefore, the polarizing film of the present invention can balance the suppression of the deterioration of the polarizer due to humidification (improving the reliability of humidification) and the suppression of cracks.

Forms for carrying out the invention 1. Polarizing film The polarizing film of the present invention is provided with a protective film on one side or both sides of the polarizer through an adhesive layer, and at least one of the aforementioned protective films provided on the polarizer satisfies the following Scription (1). Y≦1.26×lnX+3.5 (1) Y: Linear expansion coefficient of protective film (×10 ^-5 /K) X: Breaking elongation of protective film (%)

Each component will be described below.

(1) Polarizer The polarizer can be any known one without any limitation, but from the viewpoint of thinning and suppressing the occurrence of cracks, it is preferable to use a polarizer with a thickness of 10 μm or less. The thickness of the polarizer is more preferably 8 μm or less, 7 μm or less, and 6 μm or less. On the other hand, the thickness of the polarizer is 2 μm or more, and more preferably 3 μm or more.

The polarizer is made of polyvinyl alcohol resin. Examples of polarizers include the adsorption of iodine or dichroic dyes by hydrophilic polymer films such as polyvinyl alcohol-based films, partially formalized polyvinyl alcohol-based films, and ethylene-vinyl acetate copolymer-based partially saponified films. Monochromatic substances, polyolefin oriented films such as polyvinyl alcohol dehydration treatment or polyvinyl chloride dehydrochlorination treatment, etc. Among them, a polarizer composed of a polyvinyl alcohol-based film and a dichroic substance such as iodine is more suitable.

The polarizing member in which the polyvinyl alcohol-based film is dyed with iodine and uniaxially stretched can be produced by, for example, immersing polyvinyl alcohol in an aqueous solution of iodine and dyeing it, and stretching it to 3 to 7 times its original length. If necessary, it may contain boric acid, zinc sulfate, zinc chloride, etc., or it may be immersed in an aqueous solution such as potassium iodide. Further, if necessary, the polyvinyl alcohol-based film is immersed in water and washed with water before dyeing. By washing the polyvinyl alcohol-based film with water, the dirt and anti-caking agent on the surface of the polyvinyl alcohol-based film can be washed. In addition, the polyvinyl alcohol-based film swells to prevent uneven dyeing and other unevenness. The extension can be performed after dyeing with iodine, or it can be extended while dyeing, or it can be dyed with iodine after extension. It can also be extended in an aqueous solution such as boric acid or potassium iodide or in a water bath.

From the viewpoint of extension stability and humidification reliability, the polarizer should preferably contain boric acid. In addition, from the viewpoint of suppressing the occurrence of cracks, the content of boric acid contained in the polarizer is preferably 22% by weight or less, and more preferably 20% by weight or less with respect to the total amount of the polarizer. From the standpoint of extension stability and humidification reliability, the boric acid content is preferably 10% by weight or more, and more preferably 12% by weight or more relative to the total amount of polarizers.

The representative of thin polarizers can be mentioned as follows: Specification of Japanese Patent No. 4751486, Specification of Japanese Patent No. 4751481, Specification of Japanese Patent No. 4815544, Specification of Japanese Patent No. 5048120, Manual of International Publication No. 2014/077599, The thin polarizer described in the manual of International Publication No. 2014/077636, etc., or the thin polarizer produced by the manufacturing method described there.

In the manufacturing method including the step of extending in the state of a laminate and the dyeing step, from the viewpoint of extending at a high magnification and improving the polarizing performance, the thin polarizer is described in Japanese Patent No. 4751486, Japanese Patent No. 4751481 The specification described in the Japanese Patent No. 4815544 and the Japanese Patent No. 4815544 are preferably prepared by a method including a step of extending in an aqueous solution of boric acid, and are particularly as described in Japanese Patent No. 4751481 and Japanese Patent No. 4815544 Preferably, it is prepared by a method including a step of auxiliary air stretching before stretching in a boric acid aqueous solution. These thin polarizers can be produced by a manufacturing method including the following steps: a step of stretching a polyvinyl alcohol-based resin (hereinafter, also referred to as PVA-based resin) layer and a resin substrate for extension in the state of a laminate and dyeing step. As long as this production method is used, even if the PVA-based resin layer is very thin, it is supported by the resin substrate for stretching, so it can be stretched without breaking or other defects caused by the stretching.

(2) Protective film The material of the protective film should preferably be excellent in transparency, mechanical strength, thermal stability, moisture blocking property and isotropy. Examples include polyester-based polymers such as polyethylene terephthalate or polyethylene naphthalate; cellulose-based polymers such as diethyl cellulose or triethyl cellulose; polymethacrylate Acrylic polymers such as esters; styrene polymers such as polystyrene or acrylonitrile-styrene copolymers (AS resins); polycarbonate polymers and the like. In addition, the following polymers can be cited as examples of the polymer forming the above protective film: polyethylene, polypropylene, polyolefin having a ring system or a norbornene structure, such as an ethylene-propylene copolymer polyolefin polymer , Vinyl chloride polymer, nylon or aromatic polyamide amide polymer, amide imide polymer, lanyard polymer, polyether lanyard polymer, polyether ether ketone polymer, polyextrusion Phenylsulfide-based polymer, vinyl alcohol-based polymer, chlorinated vinylidene-based polymer, vinyl butyral-based polymer, aryl ester-based polymer, polyoxymethylene-based polymer, epoxy-based polymer or the above-mentioned polymer Of blends, etc.

The protective film may contain one or more arbitrary and appropriate additives. Additives include, for example, ultraviolet absorbers, antioxidants, slip agents, plasticizers, mold release agents, colorants, flame retardants, nucleating agents, antistatic agents, pigments, colorants, and the like.

The content of the polymer in the protective film is preferably 50 to 100% by weight, preferably 50 to 99% by weight, more preferably 60 to 98% by weight, and even more preferably 70 to 97% by weight. When the content of the polymer in the protective film is less than 50% by weight, there is a possibility that the high transparency and the like inherent in the polymer may not be sufficiently exhibited.

As the protective film, a phase difference film, a brightness enhancement film, a diffusion film, etc. can also be used. Examples of the retardation film include those having a frontal phase difference of 40 nm or more and/or a thickness direction phase difference of 80 nm or more. The frontal phase difference is usually controlled in the range of 40~200nm, and the thickness direction phase difference is usually controlled in the range of 80~300nm. When a retardation film is used as a protective film, the retardation film can also function as a protective film of a polarizer, so that it can be made thinner.

Examples of the retardation film include a birefringent film obtained by uniaxially or biaxially stretching a thermoplastic resin film. The stretching temperature, stretching magnification, etc. can be appropriately set according to the phase difference value, film material and thickness.

The thickness of the protective film can be appropriately determined, but it is about 1 to 500 μm from the viewpoints of workability such as strength and operability, and thinness. The thickness of the protective film is preferably 1 to 300 μm, preferably 5 to 200 μm, more preferably 5 to 150 μm, and even more preferably 20 to 100 μm.

A functional layer such as a hard coat layer, an anti-reflection layer, an anti-adhesion layer, a diffusion layer, and even an anti-glare layer may be provided on the surface of the aforementioned protective film that does not follow the polarizer. In addition, the functional layer such as the hard coat layer, the anti-reflection layer, the anti-adhesion layer, the diffusion layer, or the anti-glare layer can be provided separately from the protective film in addition to the protective film itself.

In the present invention, at least one of the protective films (which may also include the aforementioned functional layer) provided on the polarizer is one that satisfies the following formula (1). When the protective films are to be provided on both sides of the polarizer, the protective films provided on both sides of the polarizer preferably satisfy the following formula (1). In this way, the stress caused by the expansion and contraction of the polarizer can be effectively relieved, so that the polarizer can be less prone to cracks. In addition, please refer to the description of the examples for the measuring methods of the linear expansion coefficient and the breaking elongation of the protective film. Y≦1.26×lnX+3.5 (1) Y: Linear expansion coefficient of protective film (×10 ^-5 /K) X: Breaking elongation of protective film (%)

The coefficient of linear expansion and elongation at break of the protective film will vary depending on the raw materials and thickness used, so the thickness should be adjusted appropriately according to the raw materials used. The protective film satisfying the above formula (1) can be produced, for example, by extending the cycloolefin-based polymer film to a thickness of about 17 to 18 μm.

Commercial products that satisfy the protective film of the above formula (1) include, for example, TJ25UL (manufactured by Fujifilm, raw material: triacetyl cellulose polymer, thickness: 25 μm), ZT12 (manufactured by Japan Zeon, raw material: Cycloolefin-based polymer, thickness: 17 μm), KC2UA (manufactured by Konica Minolta, raw material: triacetyl cellulose polymer, thickness: 20 μm), and KC2UGR-HC (manufactured by Konica Minolta, made of triethyl cellulose polymer) The film is provided with an acrylic resin hard coat film, thickness: 37μm), etc.

The coefficient of linear expansion Y (×10 ^-5 /K) of the protective film satisfying the above formula (1) is preferably 4 or less, and preferably 3.5 or less, and more preferably 3.1 or less.

(3) Adhesive layer

The adhesive layer is formed of an adhesive. The type of adhesive is not particularly limited, and various substances can be used. The adhesive layer is not particularly limited as long as it is optically transparent. Adhesives can be used in various forms such as water-based, solvent-based, hot-melt adhesive, and active energy ray-curable types, except for water-based adhesives or active energy ray-curable types. Adhesive is appropriate.

Examples of the water-based adhesive include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latex-based adhesives, and water-based polyesters. The water-based adhesive is usually used as an adhesive composed of an aqueous solution, and usually contains 0.5 to 60% by weight of solid content.

The active energy ray-curable adhesive is an adhesive that is cured by active energy rays such as electron beams, ultraviolet rays (radical curing type, cation curing type), etc. For example, it can be used in the form of electron beam curing type or ultraviolet curing type. For the active energy ray hardening type adhesive, for example, a photo radical hardening type adhesive can be used. When the photoradical hardening type active energy ray hardening type adhesive is used as the ultraviolet hardening type, the adhesive contains a radical polymerizable compound and a photopolymerization initiator.

The application method of the adhesive can be appropriately selected according to the viscosity or the target thickness of the adhesive. Examples of the coating method include a reverse coater, a gravure coater (direct, reverse or lithography), a bar reverse coater, a roll coater, a die coater, a bar coater, and a rod coater. In addition, for coating, a method such as a dipping method can be used as appropriate.

In addition, when using an aqueous adhesive or the like for the application of the adhesive, the thickness of the adhesive layer to be finally formed is preferably 30 to 300 nm. The thickness of the aforementioned adhesive layer is more preferably 60 to 250 nm. On the other hand, when an active energy ray-curable adhesive is used, it is preferably performed so that the thickness of the adhesive layer is 0.1 to 200 μm. It is preferably 0.5-50 μm, and more preferably 0.5-10 μm.

In addition, when laminating the polarizer and the protective film, an easy adhesion layer may be provided between the protection film and the adhesive layer. The easy-adhesion layer may be formed of various resins having, for example, the following skeletons: polyester skeleton, polyether skeleton, polycarbonate skeleton, polyurethane skeleton, polysiloxane system, polyamide skeleton, polyimide skeleton , Polyvinyl alcohol skeleton, etc. These polymer resins can be used alone or in combination of two or more. In addition, other additives may be added when the easy-adhesion layer is formed. Specifically, stabilizers such as tackifiers, ultraviolet absorbers, antioxidants, heat-resistant stabilizers, and the like can be used.

The easy-adhesive layer is usually provided on the protective film in advance, and the easy-adhesive layer side of the protective film and the polarizer are laminated by an adhesive layer. The formation of the easy-adhesion layer can be carried out by applying a known technique to the formation material of the easy-adhesion layer on the protective film and drying it. The forming material of the easy-adhesion layer is usually adjusted to a solution that has been diluted to an appropriate concentration in consideration of the thickness after drying and the smoothness of the coating. The thickness of the easy-adhesion layer after drying should be 0.01-5 μm, more preferably 0.02-2 μm, and more preferably 0.05-1 μm. In addition, the easy-adhesion layer may be provided in multiple layers. In this case, the total thickness of the easy-adhesion layer should preferably fall within the above range.

2. Polarizing film with adhesive layer The polarizing film with an adhesive layer of the present invention has the polarizing film and the adhesive layer.

When a double-sided protective polarizing film is provided with protective films on both sides of the polarizer, an adhesive layer is provided directly on one side of the double-sided protective polarizing film or through other layers. In addition, a surface protective film can also be provided on the other side of the double-sided protective polarizing film directly or through other layers.

In the case of a single-sided protective polarizing film provided with a protective film on only one side of the polarizer, an adhesive layer is provided directly or through another layer on the polarizer side of the single-sided protective polarizing film. In addition, a surface protective film may be provided directly on the protective film side of the single-sided protective polarizing film or through other layers.

The aforementioned other layers are not particularly limited, and examples thereof include known functional layers and optical layers provided on the polarizing film. Examples of the optical layer include reflective plates, semi-transmissive plates, retardation plates (including 1/2 or 1/4 wavelength plates, etc.), viewing angle compensation films, and brightness enhancement films. The aforementioned other layers may be provided with one layer or two or more layers.

The adhesive layer is provided on one side of the polarizing film for bonding the polarizing film to a unit substrate such as a liquid crystal cell.

The thickness of the adhesive layer is not particularly limited. For example, it may be about 1-100 μm, preferably 2-50 μm, more preferably 2-40 μm, and even more preferably 5-35 μm.

Appropriate adhesives can be used for the formation of the aforementioned adhesive layer, and there is no particular limitation on the type. Examples of the adhesive include rubber adhesives, acrylic adhesives, polysiloxane adhesives, urethane adhesives, vinyl alkyl ether adhesives, polyvinyl alcohol adhesives, and polyvinylpyrrole. Pyridone-based adhesives, polyacrylamide-based adhesives, cellulose-based adhesives, etc.

Among these adhesives, those having good optical transparency, exhibiting moderate wettability, cohesiveness and adhesiveness, and excellent weather resistance and heat resistance are suitable for use. For those exhibiting such characteristics, it is better to use acrylic adhesives.

The method of forming the adhesive layer may be, for example, a method of applying the adhesive to a separator subjected to peeling treatment, drying and removing the polymerization solvent, etc. to form an adhesive layer, and then transferring it to the polarizing film Or the method of applying the above adhesive, drying and removing the polymerization solvent, etc. to form an adhesive layer on the polarizing film. In addition, when applying the adhesive, one or more solvents other than the polymerization solvent may be appropriately added.

The separated parts after stripping treatment should use polysilicone stripping lining material. In the step of applying an adhesive on the lining material and drying it to form an adhesive layer, the method of drying the adhesive may be an appropriate and appropriate method depending on the purpose. It is preferable to use a method in which the above coating film is overheated and dried. The heating and drying temperature is preferably 40°C to 200°C, more preferably 50°C to 180°C, and particularly preferably 70°C to 170°C. By setting the heating temperature within the above range, an adhesive having excellent adhesive properties can be obtained.

The appropriate drying time can be adopted as the drying time. The above drying time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and particularly preferably 10 seconds to 5 minutes.

Various methods can be used to form the adhesive layer. Specific examples include roll coating, contact roll coating, gravure coating, reverse coating, roll brush, spray cloth, dip roll coating, bar coating, knife coating, and air knife coating , Curtain coating, lip coating, extrusion coating method using die coater, etc.

When the adhesive layer is exposed, the peeled sheet (separator) can be used to protect the adhesive layer until it is ready for practical use.

Examples of constituent materials of the separator include plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester films; porous materials such as paper, cloth, and non-woven fabric; meshes, and foamed sheets , Metal foil, and other appropriate laminates such as laminates, etc., but from the viewpoint of excellent surface smoothness, it is suitable to use plastic film.

The plastic film is not particularly limited as long as it can protect the adhesive layer, and examples include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, and polyvinyl chloride. Film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-ethyl acetate copolymer film, etc.

The thickness of the aforementioned separator is usually 5 to 200 μm, preferably about 5 to 100 μm. The aforementioned separator can also be subjected to mold release and antifouling treatment using polysilicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based release agents, silica powder, etc., as well as coating type, Antistatic treatment such as kneading type and evaporation type. In particular, by appropriately performing peeling treatments such as polysiloxane treatment, long-chain alkyl treatment, and fluorine treatment on the surface of the separator, the peelability from the adhesive layer can be further improved.

The surface protection film usually has a base film and an adhesive layer, and the polarizing film is protected by the adhesive layer.

From the viewpoints of inspection and management, the substrate film of the surface protective film can be selected to have isotropic or nearly isotropic film materials. Examples of the film material include polyester-based resins such as polyethylene terephthalate films, cellulose-based resins, acetate-based resins, polyether-based resins, polycarbonate-based resins, and polyamide-based resins. Polyimide-based resin, polyolefin-based resin, acrylic resin-like transparent polymer. Among them, polyester resins are suitable. The base film can be used as a laminate of one or more types of film materials, or an extension of the aforementioned film can be used. The thickness of the substrate film is usually 500 μm or less, preferably 10 to 200 μm.

The adhesive for forming the adhesive layer of the surface protective film can be appropriately selected from (meth)acrylic polymer, polysiloxane polymer, polyester, polyurethane, polyamide, polyether, and fluorine Or polymers such as rubbers are used as adhesives for base polymers. From the viewpoints of transparency, weather resistance, heat resistance, etc., an acrylic adhesive using an acrylic polymer as a base polymer is suitable. The thickness of the adhesive layer (dry film thickness) can be determined according to the required adhesive force. Usually it is about 1~100μm, preferably 5~50μm.

In addition, the surface protection film may be provided with a peeling treatment layer on the opposite surface of the base film with the adhesive layer by a low-adhesion material such as polysiloxane treatment, long-chain alkyl treatment, or fluorine treatment.

3. Image display device The image display device of the present invention only needs to include the polarizing film of the present invention or the polarizing film with an adhesive layer, and the rest of the configuration may be the same as the conventional image display device. The aforementioned polarizing film or the polarizing film with an adhesive layer can be applied to the image display unit. For example, when the image display device is a liquid crystal display device, the polarizing film or the polarizing film with an adhesive layer can be applied to either the viewing side or the backlight side of the image display unit (liquid crystal unit). When the image display device is an organic EL display device, the polarizing film or the polarizing film with an adhesive layer can be applied to the viewing side of the image display unit. Since the image display device of the present invention includes the polarizing film or the polarizing film with an adhesive layer, it has high reliability. Examples

Hereinafter, the present invention will be specifically described with examples, but the present invention is not limited by these examples. As for the parts and% in each case are based on weight.

(Make polarizer) Corona treatment is applied to one side of the substrate of amorphous isophthalic acid copolymerized polyethylene terephthalate (IPA copolymerized PET) film (thickness: 100 μm) with a water absorption of 0.75% and Tg75°C. The treated surface was coated with polyvinyl alcohol (degree of polymerization: 4200, degree of saponification: 99.2 mol%) and modified PVA (degree of polymerization: 1200, degree of ethyl acetate) at a ratio of 9:1 at 25°C. Acrylic modification degree: 4.6%, saponification degree: 99.0 mol% or more, manufactured by Japan Synthetic Chemical Industry Co., Ltd., trade name "Gohsefimer Z200") and dried to form a PVA resin layer with a thickness of 11 μm. Out of the laminate. In an oven at 120° C., the obtained laminate was uniaxially stretched by 2.0 times in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds in the longitudinal direction (longitudinal direction) (air assisted stretching treatment). Next, the laminate was immersed in an insoluble bath (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 30°C for 30 seconds (insoluble treatment). Next, it was immersed in a dyeing bath at a liquid temperature of 30°C, and the iodine concentration and the immersion time were adjusted at the same time to make the polarizing plate a predetermined transmittance. In this example, it was immersed in an aqueous iodine solution obtained by mixing 0.2 parts by weight of iodine and 1.0 parts by weight of potassium iodide with respect to 100 parts by weight of water for 60 seconds (dyeing treatment). Next, it was immersed in a crosslinking bath (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 30°C (crosslinking treatment) . Then, while immersing the laminate in a boric acid aqueous solution having a liquid temperature of 70° C. (an aqueous solution obtained by blending 4.5 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water), the rollers differ in the peripheral speed. Uniaxial stretching is carried out in the longitudinal direction (longitudinal direction) so that the total stretching magnification is 5.5 times (underwater stretching treatment). Thereafter, the laminate was immersed in a washing bath (aqueous solution obtained by mixing 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 30° C. (washing treatment). In the above-mentioned manner, an optical film laminate including a polarizer having a thickness of 5 μm was produced. The boric acid content of the prepared polarizer was 20% by weight.

(Making adhesives for protective films) 40 parts by weight of N-hydroxyethyl acrylamide (HEAA), 60 parts by weight of acryloyl morpholin (ACMO) and 3 parts by weight of photoinitiator "IRGACURE 819" (manufactured by BASF) are mixed to prepare ultraviolet rays Hardening adhesive.

Example 1 (Making single-sided protective polarizing film) On the surface of the polarizer (thickness: 5 μm) of the above-mentioned optical film laminate, apply the above-mentioned ultraviolet curing adhesive so that the thickness of the adhesive layer after curing becomes 0.1 μm, and simultaneously attach the protective film 1 (attached HC's 25μm TAC film: TJ25UL (made by Fujifilm, raw material: triacetyl cellulose-based polymer, thickness: 25μm) film with acrylic resin-based hard coating), irradiated with ultraviolet rays as active energy rays The aforementioned adhesive is hardened. Then, the amorphous PET substrate provided on one side of the polarizer is peeled off to produce a single-sided protective polarizing film.

Examples 2, 3, 6-8, Comparative Examples 1-8 A single-sided protective polarizing film was produced in the same manner as in Example 1 except that the protective film 1 described in Table 1 was used.

Example 4 (Making double-sided protective polarizing film) On the surface of the polarizer (thickness: 5 μm) of the above-mentioned optical film laminate, apply the above-mentioned ultraviolet curing adhesive so that the thickness of the adhesive layer after curing becomes 0.1 μm, and simultaneously attach the protective film 1 (attached HC's 25μm TAC film: TJ25UL (made by Fujifilm, raw material: triacetyl cellulose-based polymer, thickness: 25μm) film with acrylic resin-based hard coating), irradiated with ultraviolet rays as active energy rays The aforementioned adhesive is hardened. After that, the non-crystalline PET substrate provided on one side of the polarizer is peeled off, and the ultraviolet curing adhesive is applied on the peeling surface so that the thickness of the cured adhesive layer becomes 0.1 μm, and the protection is applied at the same time. Film 2 (25 μm TAC film: TJ25UL (manufactured by Fujifilm, raw material: triacetyl cellulose-based polymer, thickness: 25 μm)), irradiated with ultraviolet rays as an active energy ray to harden the adhesive to produce double-sided protection Polarizing film.

Examples 5, 9, 10, and Comparative Example 9 Using the protective films 1 and 2 described in Table 1, except that the double-sided protective polarizing film was produced in the same manner as in Example 4.

The protective films 1 and 2 described in Table 1 are as follows.

25μm TAC film with HC: TJ25UL (manufactured by Fujifilm, raw material: triethyl cellulose polymer, thickness: 25μm) film with acrylic resin hard coating

25μm TAC film: TJ25UL (manufactured by Fujifilm, raw material: triacetyl cellulose polymer, thickness: 25μm)

17μm COP film: ZT12 (made by Japan Zeon, cycloolefin polymer film biaxially stretched with a frontal phase difference of 116nm and a thickness phase difference of 81nm, thickness: 17μm)

20μm TAC film: KC2UA (manufactured by Konica Minolta, raw material: triacetyl cellulose polymer, thickness: 20μm)

Manufacturing method of 20μm acrylic film In a 30-liter kettle-type reactor equipped with a stirring device, a temperature sensor, a cooling tube, and a nitrogen introduction tube, feed 8,000 g of methyl methacrylate (MMA) and 2,000 g of 2-(hydroxymethyl) Methyl acrylate (MHMA), 10,000g of 4-methyl-2-pentanone (methyl isobutyl ketone, MIBK), 5g of n-dodecanethiol, and heated to 105°C while passing nitrogen through After refluxing, 5.0 g of tertiary butylperoxy isopropyl carbonate (Kayakarubon BIC-7, manufactured by KAYAKU AKZO CO., LTD.) was added as a polymerization initiator, and it took 4 hours to drop 30.0 of tertiary from 10.0 g A solution consisting of butyl peroxy isopropyl carbonate and 230 g of MIBK is subjected to solution polymerization at about 105 to 120° C. under reflux, and it takes another 4 hours to ripen. Add 30g of octadecyl phosphate/di(octadecyl) phosphate mixture (Phoslex A-18, manufactured by Sakai Chemical Industry Co., Ltd.) to the prepared polymer solution, and under reflux at about 90~120 Cyclization condensation reaction was carried out at ℃ for 5 hours. Next, the prepared polymer solution was introduced into a sleeve temperature of 260°C, a rotation speed of 100 rpm, a decompression degree of 13.3 to 400 hPa (10 to 300 mmHg), and a number of rear vent holes at a processing speed converted to 2.0 kg/h in terms of the amount of resin One vented twin-screw extruder with four front vents (φ=29.75mm, L/D=30), and further cyclization condensation reaction and devolatization in the extruder Extrusion is performed to obtain transparent pellets of the lactone ring-containing polymer. After performing dynamic TG measurement on the prepared polymer containing lactone ring, a mass loss of 0.17% by mass was detected. In addition, the weight average molecular weight of the lactone ring-containing polymer was 133,000, the melt flow rate was 6.5 g/10 min, and the glass transition temperature was 131°C. Using a uniaxial extruder (screw 30mmφ), the obtained pellets and acrylonitrile-styrene (AS) resin (TOYO AS AS20, manufactured by TOYO STYRENE CO., LTD.) were kneaded and extruded at a mass ratio of 90/10 To produce transparent pellets. The glass transition temperature of the resulting pellets was 127°C. The pellets were melt extruded from a 400 mm wide hanger-type T-die using a 50 mmφ uniaxial extruder to produce a film with a thickness of 80 μm. In addition, it was melt-extruded while supplying an ultraviolet absorbent (product name: LA-F70 manufactured by ADEKA Corporation) of 0.66 parts by weight with respect to 100 parts by weight of the resin in the pellets. Using a biaxial stretching device, the produced film was stretched 2.0 times under the temperature condition of 150° C., thereby obtaining a stretched film (20 μm acrylic film) with a thickness of 20 μm. After measuring the optical properties of the stretched film, the total light transmittance was 93%, the in-plane phase difference Δnd was 0.8 nm, and the thickness direction phase difference Rth was 1.5 nm.

Manufacturing method of 40μm acrylic film (UV) MS resin (MS-200; copolymer of methyl methacrylate/styrene (mole ratio) = 80/20, manufactured by Nippon Steel Chemical Co., Ltd.) was subjected to imidateization with monomethylamine (acetamide) Amination rate: 5%). In addition, the aforementioned amidation is the use of a 15mm caliber type co-rotating biaxial extruder. The temperature of each temperature adjustment zone of the extruder was set at 230°C, the screw rotation speed was 150 rpm, and the MS resin was supplied at 2.0 kg/hr. The amount of monomethylamine supplied was 2 parts by weight relative to 100 parts by weight of the MS resin. Copies. After feeding MS resin from the feed hopper and kneading the molten resin to fill it, monomethylamine was injected from the nozzle. Put a sealing ring at the end of the reaction zone and fill it with resin. The pressure of the exhaust port is reduced to -0.08MPa to devolatize the by-products and excessive methylamine after the reaction. After the resin sent from the die set at the exit of the extruder to form a bundle is cooled in a water tank, it is pelletized by a pelletizer. The aforementioned imidized MS resin was melt-extruded and formed into a film. At this time, 0.66 parts by weight of an ultraviolet absorber (manufactured by ADEKA, trade name: LA-F70) was supplied to 100 parts by weight of MS resin. Next, biaxial stretching was performed twice as long and twice as wide to produce a protective film (40 μm acrylic film (UV), thickness 40 μm, Re=2 nm, Rth=2 nm).

Method for manufacturing 30 μm acrylic film containing cross-linked elastomer The mixture having the following composition was fed into a glass reactor, and the temperature was raised to 80°C while stirring in a nitrogen stream, and 25 parts of methyl methacrylate and 1 part of allyl methacrylate were fed at once. 25% of the mixture of 0.1 parts of the monomer mixture and tertiary butyl hydrogen peroxide was polymerized for 45 minutes. Deionized water 　　　　　　　　　　220 copies Boric acid 　　　　　　　　　　　　0.3 servings Sodium carbonate 　　　　　　　　　　　0.03 servings N-laurel sodium sarcosinate 　　　　　　0.09 servings Sodium formaldehyde hyposulfite 　　　　　　　0.09 servings Ethylenediaminetetraacetic acid 2-sodium 　　　　　　0.006 servings Ferrous sulfate 　　　　　　　　　　0.002 servings Then the remaining 75% of the mixed solution was continuously added for 1 hour. After the addition was completed, the polymerization was completed after maintaining at this temperature for 2 hours. In addition, 0.2 parts of N-lauryl sarcosinate was added during the period. The polymerization conversion rate (polymerization yield/monomer feed amount) of the prepared innermost crosslinked methacrylic polymer latex was 98%. The innermost polymer latex prepared was maintained at 80°C in a nitrogen stream, and after adding 0.1 part of potassium persulfate, it took 5 hours to continuously add 41 parts of n-butyl acrylate, 9 parts of styrene, and methacrylic acid A monomer mixture consisting of 1 part of allyl ester. During this period, 0.1 part of potassium oleate was added three times. After the monomer mixture was added, in order to complete the polymerization, 0.05 parts of potassium persulfate was further added and held for 2 hours to obtain rubber particles. The prepared rubber particles had a polymerization conversion rate of 99% and a particle size of 225 nm. The obtained rubber particle latex was maintained at 80°C, and after adding 0.02 parts of potassium persulfate, a monomer mixture of 14 parts of methyl methacrylate and 1 part of n-butyl acrylate was continuously added over 1 hour. After adding the monomer mixture, it was kept for 1 hour to prepare a graft copolymer latex. The polymerization conversion rate was 99%. The obtained graft copolymer latex was maintained at 80°C, and a monomer mixture of 5 parts of methyl methacrylate and 5 parts of n-butyl acrylate was continuously added over 0.5 hours. After adding the monomer mixture, it was kept for 1 hour to prepare a rubber-containing graft copolymer latex. The polymerization conversion rate was 99%. The obtained rubber-containing graft copolymer latex was salted out and solidified with calcium chloride, heat-treated, and dried to obtain a white powder-like crosslinked elastomer. MS resin (MS-200; copolymer of methyl methacrylate/styrene (mole ratio) = 80/20, manufactured by Nippon Steel Chemical Co., Ltd.) was subjected to imidateization with monomethylamine (acetamide) Amination rate: 5%). In addition, the aforementioned amidation is the use of a 15mm caliber type co-rotating biaxial extruder. The temperature of each temperature adjustment zone of the extruder was set at 230°C, the screw rotation speed was 150 rpm, and the MS resin was supplied at 2.0 kg/hr. The amount of monomethylamine supplied was 2 parts by weight relative to 100 parts by weight of the MS resin. Copies. After feeding MS resin from the feed hopper and kneading the molten resin to fill it, monomethylamine was injected from the nozzle. Put a sealing ring at the end of the reaction zone and fill it with resin. The pressure of the exhaust port is reduced to -0.08MPa to devolatize the by-products and excessive methylamine after the reaction. After the resin sent from the die set at the exit of the extruder to form a bundle is cooled in a water tank, it is pelletized by a pelletizer. The aforementioned imidized MS resin was melt-extruded and formed into a film. At this time, 0.66 parts by weight of an ultraviolet absorber (manufactured by ADEKA, trade name: LA-F70) was supplied to 100 parts by weight of MS resin. Next, 10 parts by weight of the aforementioned cross-linked elastomer was supplied to 100 parts by weight of the MS resin. Next, the extruded 160 μm film was biaxially stretched to 2 times in length and 2 times in width to produce a protective film (30 μm acrylic film including cross-linked elastomer, thickness 30 μm, Re=2 nm, Rth=2 nm) .

37μmλ/4TAC film with HC: KC2UGR-HC (made by Konica Minolta, triacetyl cellulose-based polymer film with acrylic resin-based hard coating, thickness: 37μm)

13μm COP film: ZF-014 (made by Japan Zeon, raw material: cycloolefin polymer, thickness: 13μm)

26μmλ/4COP film with HC: ZD12 (made by Japan Zeon, raw material: cycloolefin polymer, thickness: 20μm) film with acrylic resin hard coating

Manufacturing method of 40μm acrylic film with HC in a 30L kettle type reactor equipped with stirring device, temperature sensor, cooling tube, nitrogen introduction tube, feeding 8,000g of methyl methacrylate (MMA), 2,000 g of 2-(hydroxymethyl) methyl acrylate (MHMA), 10,000g of 4-methyl-2-pentanone (methyl isobutyl ketone, MIBK), 5g of n-dodecanethiol, and use After nitrogen was heated to 105°C and refluxed through one side, 5.0 g of tertiary butyl peroxy isopropyl carbonate (Kayakarubon BIC-7, manufactured by KAYAKU AKZO CO., LTD.) was added as a polymerization initiator, and it took A solution composed of 10.0 g of tertiary butylperoxyisopropyl carbonate and 230 g of MIBK was dropped in 4 hours, and solution polymerization was carried out at about 105 to 120° C. under reflux, and it took another 4 hours for aging. Add 30g of octadecyl phosphate/di(octadecyl) phosphate mixture (Phoslex A-18, manufactured by Sakai Chemical Industry Co., Ltd.) to the prepared polymer solution, and under reflux at about 90~120 Cyclization condensation reaction was carried out at ℃ for 5 hours. Next, the prepared polymer solution was introduced into a sleeve temperature of 260°C, a rotation speed of 100 rpm, a decompression degree of 13.3 to 400 hPa (10 to 300 mmHg), and a number of rear vent holes at a processing speed converted to 2.0 kg/h in terms of the amount of resin One vented twin-screw extruder with four front vents (φ=29.75mm, L/D=30), and further cyclization condensation reaction and devolatization in the extruder Extrusion is performed to obtain transparent pellets of the lactone ring-containing polymer. After performing dynamic TG measurement on the prepared polymer containing lactone ring, a mass loss of 0.17% by mass was detected. In addition, the weight average molecular weight of the lactone ring-containing polymer was 133,000, the melt flow rate was 6.5 g/10 min, and the glass transition temperature was 131°C. Using a uniaxial extruder (screw 30mmφ), the obtained pellets and acrylonitrile-styrene (AS) resin (TOYO AS AS20, manufactured by TOYO STYRENE CO., LTD.) were kneaded and extruded at a mass ratio of 90/10 To produce transparent pellets. The glass transition temperature of the resulting pellets was 127°C. The pellets were melt extruded from a 400 mm wide hanger-type T-die using a 50 mmφ uniaxial extruder to produce a film with a thickness of 160 μm. Using a biaxial stretching device, the produced film was stretched 2.0 times at a temperature of 150°C, thereby obtaining a stretched film with a thickness of 40 μm. After measuring the optical properties of the stretched film, the total light transmittance was 93%, the in-plane phase difference Δnd was 0.8 nm, and the thickness direction phase difference Rth was 1.5 nm. The resin contained in the coating solution is prepared with 70 parts by weight of ultraviolet-curable resin (manufactured by Shin Nakamura Chemical Industry Co., Ltd., trade name "NK oligomer UA-53H-80BK" solid content concentration 80%) and 30 parts by weight A portion of UV-curable resin (manufactured by Shin Nakamura Chemical Co., Ltd., trade name "A-GLY-9E" solid content concentration 100%). For every 100 parts by weight of the resin solid content of the aforementioned resin, 5 parts of a photopolymerization initiator (made by BASF (stock), product name "IRGACURE907") and 0.1 parts of a leveling agent (made by DIC (product), product name "GRANDIC PC4100" are added ). Toluene and cyclopentanone were added to the above blending liquid at a ratio of 80:20 to make the solid content concentration in the above solution 40%. The hard coating forming material is produced through the above procedure. The produced hard coat layer forming material was applied to the stretched film so that the thickness of the hard coat layer after curing became 7 μm to form a coating film. After that, the coating film was dried at 90° C. for 1 minute, and the coating film was irradiated with ultraviolet light with a cumulative light amount of 300 mJ/cm ² by a high-pressure mercury lamp to harden the coating film to form a hard coat layer to produce a 40 μm acrylic film with HC.

Manufacturing method of 30 μm acrylic film with cross-linked elastomer with HC attached 15-functional urethane acrylate oligomer (manufactured by Shin Nakamura Chemical Co., Ltd., trade name: NK Oligo UA-53H, weight average molecular weight: 2300) 22 Parts, neopentaerythritol triacrylate (manufactured by Osaka Organic Chemical Industry Co., Ltd., trade name: Viscoat#300) 28 parts, ethoxylated glycerin triacrylate (manufactured by Shin Nakamura Chemical Co., Ltd., trade name: NK Ester A-GLY -9E) 50 parts, 3 parts of a photopolymerization initiator (manufactured by Ciba Japan, trade name: IRGACURE 907), and diluted with methyl isobutyl ketone to a solid content concentration of 40% to produce a hard coat forming material . The produced hard coat layer forming material was applied to the aforementioned 30 μm acrylic film containing the crosslinked elastomer so that the thickness of the hard coat layer after curing became 10 μm to form a coating film. After that, the coating film was dried at 90°C for 1 minute, and the coating film was irradiated with ultraviolet light with a cumulative light amount of 200 mJ/cm ² by a high-pressure mercury lamp to harden the coating film to form a hard coating layer to produce a cross-linked elastomer with HC. 30μm acrylic film.

Manufacturing method of 40μm acrylic film In a 30-liter kettle-type reactor equipped with a stirring device, a temperature sensor, a cooling tube, and a nitrogen introduction tube, feed 8,000 g of methyl methacrylate (MMA) and 2,000 g of 2-(hydroxymethyl) Methyl acrylate (MHMA), 10,000g of 4-methyl-2-pentanone (methyl isobutyl ketone, MIBK), 5g of n-dodecanethiol, and heated to 105°C while passing nitrogen through After refluxing, 5.0 g of tertiary butylperoxy isopropyl carbonate (Kayakarubon BIC-7, manufactured by KAYAKU AKZO CO., LTD.) was added as a polymerization initiator, and it took 4 hours to drop 30.0 of tertiary from 10.0 g A solution consisting of butyl peroxy isopropyl carbonate and 230 g of MIBK is subjected to solution polymerization at about 105 to 120° C. under reflux, and it takes another 4 hours to ripen. Add 30g of octadecyl phosphate/di(octadecyl) phosphate mixture (Phoslex A-18, manufactured by Sakai Chemical Industry Co., Ltd.) to the prepared polymer solution, and under reflux at about 90~120 Cyclization condensation reaction was carried out at ℃ for 5 hours. Next, the prepared polymer solution was introduced into a sleeve temperature of 260°C, a rotation speed of 100 rpm, a decompression degree of 13.3 to 400 hPa (10 to 300 mmHg), and a number of rear vent holes at a processing speed converted to 2.0 kg/h in terms of the amount of resin One vented twin-screw extruder with four front vents (φ=29.75mm, L/D=30), and further cyclization condensation reaction and devolatization in the extruder Extrusion is performed to obtain transparent pellets of the lactone ring-containing polymer. After performing dynamic TG measurement on the prepared polymer containing lactone ring, a mass loss of 0.17% by mass was detected. In addition, the weight average molecular weight of the lactone ring-containing polymer was 133,000, the melt flow rate was 6.5 g/10 min, and the glass transition temperature was 131°C. Using a uniaxial extruder (screw 30mmφ), the obtained pellets and acrylonitrile-styrene (AS) resin (TOYO AS AS20, manufactured by TOYO STYRENE CO., LTD.) were kneaded and extruded at a mass ratio of 90/10 To produce transparent pellets. The glass transition temperature of the resulting pellets was 127°C. The pellets were melt extruded from a 400 mm wide hanger-type T-die using a 50 mmφ uniaxial extruder to produce a film with a thickness of 160 μm. Using a biaxial stretching device, the produced film was stretched 2.0 times under the temperature condition of 150°C, thereby obtaining a stretched film (40 μm acrylic film) with a thickness of 40 μm. After measuring the optical properties of the stretched film, the total light transmittance was 93%, the in-plane phase difference Δnd was 0.8 nm, and the thickness direction phase difference Rth was 1.5 nm.

APF: Brightening film (made by Sumitomo 3M, trade name: APF, thickness 26 μm)

APF with HC: Brightening film (made by Sumitomo 3M, trade name: APF, thickness 20μm) with acrylic resin hard coating film

26μm COP film with HC: ZF12-HC: made by ZEON, Japan, raw materials: those with acrylic resin hard coating on cycloolefin polymer

The methods of measuring the linear expansion coefficient and the breaking elongation of the protective films used in Examples and Comparative Examples are as follows. The polarizing films produced in Examples and Comparative Examples were evaluated as follows. The results are listed in Table 1.

>Measure the linear expansion coefficient Y (×10 ^-5 /K) of the protective film> Using a TMA analyzer (manufactured by Hitachi High-Tech Science Co., TMA7100E), measure the dimensional change of the protective film under the following measurement conditions, and obtain The value is substituted into the following formula (A) to calculate the dimensional change rate. Four measurements were made and the average value of four times was used as the dimensional change rate. Then, the average value of the obtained dimensional change rate was substituted into the following formula (B) to calculate the linear expansion coefficient Y (×10 ^-5 /K) of the protective film. Sample size: 20mm×5mm Measurement environment: -40℃⇔85℃ Heating and cooling rate: 10℃/min Number of measurements: 4 Dimensional change rate=(ΔL/L)×100 (A) ΔL: Dimensional change during measurement Quantity (the difference between the size at -40°C and the size at 85°C) L: The size before measurement (the size at 25°C) Linear expansion coefficient Y (×10 ^-5 /K) = (dimension change rate /ΔT)/100 (B) ΔT: temperature change range

>Measure the breaking elongation X(%) of the protective film> Using an Autograph (manufactured by Shimadzu Corporation) under the following measurement conditions, the film was stretched at a fixed speed until the protective film was broken, and the length at break was measured. The initial length and the length at break were substituted into the following formula (C) to calculate the breaking elongation X (%). Three measurements were made and the average value of three times was taken as the elongation at break X (%). Sample size: 100mm×10mm Stretching speed: 300mm/min Measurement environment: temperature 23℃, humidity 50%RH Number of determinations: 3 Elongation at break X (%) = {(length at break-initial length)/initial length}×100　　　(C)

>Butterfly Test of Polarized Film (Crack Resistance Test)> As shown in Figure 1, a polarizing film of 150 mm × 50 mm was cut with a laser in the MD direction to prepare a sample. This sample was bonded to a glass plate (manufactured by Songlang Glass Industry Co., Ltd.) using a manual roller through an adhesive, and the sample bonded to the glass plate was placed in an autoclave at 50°C for 15 minutes. After that, the sample attached to the glass plate was put into a test tank, and a thermal shock test was conducted under the following conditions. The sample attached to the glass plate is taken out every 10 cycles, and it is confirmed whether there is a crack of more than 1 mm in the circled part of FIG. The number of cycles when cracks of 1 mm or more were generated was counted for each of the five samples (the number of cycles where five of the five samples all had cracks), and the maximum value among them was evaluated according to the following criteria. (Measurement conditions) Measurement environment: -40℃ (maintain for 30 minutes) ⇔ 85℃ (maintain for 30 minutes) Heating and cooling speed: 10℃/min Number of samples: 5 (Evaluation criteria) 〇: 200 cycles or more △: 100~199 cycles ×: 99 cycles or less

[Table 1]

It can be seen from Table 1 that at least one of the protective films provided on the polarizer satisfies the polarizing films of Examples 1 to 10 of the above formula (1), even under thermal shock (repeatedly under the temperature conditions of -40°C and 85°C Thermal shock test) is not easy to produce cracks in polarized parts, and it has excellent crack resistance. On the other hand, it can be seen that the polarizing films of Comparative Examples 1 to 9 in which the protective film provided on the polarizer does not satisfy the above formula (1) are prone to cracks in the polarizer due to thermal shock and have poor crack resistance.

Industrial availability The polarizing film of the present invention can be used alone or in the form of a laminated optical film for image display devices such as liquid crystal display devices (LCDs) and organic EL display devices.

Fig. 1 is a schematic diagram showing the shape of a sample used in a butterfly test.

Claims (5)

A polarizing film is provided with a protective film on one side or both sides of a polarizer through an adhesive layer. The polarizing film is characterized in that at least one of the protective films provided on the polarizer satisfies the following formula (1): Y≦1.26×lnX+3.5 (1) Y: Coefficient of linear expansion of protective film (×10 ^-5 /K) X: Breaking elongation of protective film (%). The polarizing film according to claim 1, wherein the aforementioned Y (×10 ^-5 /K) is 4 or less. The polarizing film according to claim 1 or 2, wherein the thickness of the polarizing member is 10 μm or less. A polarizing film with an adhesive layer, comprising the polarizing film according to any one of claims 1 to 3 and an adhesive layer. An image display device, wherein the image display unit is provided with a polarizing film according to any one of claims 1 to 3 or a polarizing film with an adhesive layer according to claim 4.

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