TW202402536A - Polarizing plate - Google Patents

Abstract

An object of the present invention is to provide a polarizing plate which has a protective film capable of satisfactorily suppressing blocking, while suppressing surface defects and haze. The polarizing plate contains a polarizer, an adhesive layer, and a protective film in this order. The protective film has a substrate layer and an easy-adhesion layer laminated on the adhesive layer side of the substrate layer. The easy-adhesive layer has a haze of 3% or more, and the polarizing plate has a haze of 0.5% or less. The curl amount in the absorption axis direction of the polarizing plate at a temperature of 25 DEG C and a relative humidity of 55% is -5.0% or more and 5.0% or less.

Description

polarizing plate

The present invention relates to a polarizing plate, and more particularly to an optical laminated body and a display device equipped with a polarizing plate, and a method for manufacturing the polarizing plate.

In display devices such as liquid crystal display devices and organic EL display devices, it is known that a polarizing plate is disposed on the viewing side. Polarizing plates are generally used as protective films on one or both sides of a polarizer to protect the polarizer. In order to improve the adhesion between the protective film and the polarizer, an easy-adhesion layer is sometimes provided on the surface of the protective film (for example, Patent Document 1, etc.). In Patent Document 1, in order to suppress blocking that occurs when a protective film is rolled into a roll, it is disclosed that an easy-adhesive agent composition containing fine particles is used to form an easy-adhesive layer, and microscopic particles are formed on the surface of the easy-adhesive layer. The concave and convex.

[Prior technical literature]

[Patent Document]

[Patent Document 1] Japanese Patent No. 5354733

When the amount of fine particles in the easy-adhesive layer is increased in order to effectively suppress the adhesion of the protective film, the haze of the easy-adhesive layer increases, and when the protective film is rolled into a roll, there are unevenness caused by the fine particles. The surface of the protective film is deformed, etc. Such deformation of the protective film may cause surface defects in the polarizing plate obtained by laminating the protective film on the polarizing element, and may cause deterioration in the display characteristics of a display device using the polarizing plate.

The object of the present invention is to provide a manufacturing method of a polarizing plate and a polarizing plate. The polarizing plate is equipped with a protective film that can effectively inhibit adhesion and can inhibit surface defects and haze.

The present invention provides the following polarizing plate, optical laminate, display device, and method for manufacturing the polarizing plate.

[1] A polarizing plate, which is provided with a polarizer, an adhesive layer, and a protective film in this order, wherein:

The protective film has a base material layer and an easy-adhesive layer laminated on the adhesive layer side of the base material layer,

The haze of the aforementioned easy-adhesive layer is above 3%.

The haze of the aforementioned polarizing plate is below 0.5%.

At a temperature of 25°C and a relative humidity of 55%, the amount of warpage in the absorption axis direction of the polarizing plate is -5.0% or more and 5.0% or less.

[2] The polarizing plate according to [1], wherein the thickness of the base layer is 30 μm or less.

[3] The polarizing plate according to [1] or [2], wherein the thickness of the easy-adhesion layer is 70 nm or more and 800 nm or less.

[4] The polarizing plate according to any one of [1] to [3], wherein the thickness of the polarizer is 12 μm or less.

[5] The polarizing plate according to any one of [1] to [4], wherein the polarizing element contains polyvinyl alcohol-based resin,

The shrinkage rate in the absorption axis direction of the polarizer at a temperature of 80°C is 1.3N/2mm or more and 2.4N/2mm or less.

[6] The polarizing plate according to any one of [1] to [5], wherein the polarizing element contains polyvinyl alcohol-based resin and boron,

The boron content of the polarizer is 2.8 mass% or more and 4.7 mass% or less.

[7] The polarizing plate according to any one of [1] to [6], wherein the base material layer is a (meth)acrylic resin film.

[8] The polarizing plate according to any one of [1] to [7], wherein the easily bonded layer contains a resin and a filler.

[9] The polarizing plate according to any one of [1] to [8], wherein the adhesive layer is a hardened material layer of a water-based adhesive.

[10] The polarizing plate according to any one of [1] to [9], wherein the thickness of the adhesive layer is 10 nm or more and 200 nm or less.

[11] An optical laminate including the polarizing plate, the retardation body, and the adhesive layer described in any one of [1] to [10] in this order.

[12] A display device including the optical layered body according to [11].

[13] A method of manufacturing a polarizing plate, which is provided with a polarizer, an adhesive layer, and a protective film in order, and the method of manufacturing a polarizing plate includes the following steps:

Step (a) is to prepare a laminated film having a base material layer and an easy-adhesion layer formed on the base material layer;

Step (b) is to anneal the aforementioned laminated film to obtain the aforementioned protective film;

Step (c) is to bond the polarizer on the side of the easy-adhesive layer in front of the protective film through the adhesive composition used to form the adhesive layer; wherein,

The haze of the easily adhesive layer in the laminated film is 3% or more,

The haze of the aforementioned polarizing plate is less than 0.5%.

[14] The manufacturing method of a polarizing plate according to [13], wherein the base material layer in the laminated film is a biaxially stretched film stretched in the first direction and the second direction,

The stretching ratio in the first direction is the same as or smaller than the stretching ratio in the second direction,

The ratio of the stretch ratio in the first direction to the stretch ratio in the second direction (first direction/second direction) is 0.70 or more and 1.00 or less,

The aforementioned step (b) is to perform annealing treatment so that the shrinkage rate of the aforementioned laminated film in the aforementioned second direction becomes 0.30% or less,

The aforementioned step (c) is to bond the polarizer and the protective film so that the angle between the absorption axis direction of the polarizer and the first direction of the laminated film becomes -20° or more and 20° or less.

[15] The method for manufacturing a polarizing plate according to [13] or [14], wherein the step (b) involves annealing the laminated film at a temperature of not less than 75°C and not more than 105°C.

[16] The method for manufacturing a polarizing plate according to any one of [13] to [15], wherein the thickness of the base layer in the laminated film is 30 μm or less.

[17] The method for manufacturing a polarizing plate according to any one of [13] to [16], wherein the adhesive composition is a water-based adhesive.

[18] The manufacturing method of a polarizing plate according to any one of [13] to [17], wherein the polarizing element contains polyvinyl alcohol-based resin and boron,

The boron content of the polarizer is 2.8 mass% or more and 4.7 mass% or less.

According to the present invention, it is possible to provide a manufacturing method of a polarizing plate and a polarizing plate that is provided with a protective film that can effectively suppress adhesion and can suppress surface defects and haze.

1:Polarizing plate

10:Polarizer

20:Protective film

21:Substrate layer

22: Easy to adhere layer

30: Phase difference body

31: 1st phase difference layer

32: 2nd phase difference layer

33: 2nd laminating layer

41:Adhesive layer

42: Adhesive layer

43: 1st laminating layer

120:Laminated film

121:Substrate layer

122:Easy bonding layer

FIG. 1 is a schematic cross-sectional view of a polarizing plate according to an embodiment of the present invention.

FIG. 2 is a cross-sectional view schematically showing the manufacturing steps of the polarizing plate according to one embodiment of the present invention.

FIG. 3 is a cross-sectional view schematically showing an optical laminate according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following embodiments. In each drawing, the same components as those previously described are assigned the same reference numerals and their descriptions are omitted. All the following drawings are shown to help the understanding of the present invention, and the size or shape of each component shown in the drawings may not necessarily match the size or shape of the actual component.

(Polarizing plate)

FIG. 1 is a schematic cross-sectional view of a polarizing plate according to an embodiment of the present invention. The polarizing plate 1 of this embodiment includes a polarizer 10, an adhesive layer 41, and a protective film 20. The polarizing plate 1 may be a linear polarizing plate. The protective film 20 has a base material layer 21 and an easy-adhesion layer 22 laminated on the polarizer 10 side of the base material layer 21 . The adhesive layer 41 is preferably in direct contact with the polarizer 10 and the easy-adhesive layer 22 of the protective film 20 . The details of each layer constituting the polarizing plate 1 will be described later.

The polarizing plate 1 is as shown in FIG. 1 . Although the polarizer 10 may have an adhesive layer 41 and a protective film 20 on only one side thereof, it may also have an adhesive layer 41 and a protective film 20 on both sides of the polarizer 10 . When only one side of the polarizer 10 has the adhesive layer 41 and the protective film 20 , the adhesive layer 41 and the protective film 20 are preferably disposed on the viewing side of the polarizer 10 .

The haze of the polarizing plate 1 is 0.5% or less, may be 0.4% or less, may be 0.3% or less, may be 0.2% or less, for example, may be 0.01% or more, may be 0.1% or more. The haze of the polarizing plate 1 can depend on the bonding state of the protective film 20 and the adhesive layer 41, the type and thickness of the easy-adhesive layer 22, the surface conditions of the base material layer 21 and the easy-adhesive layer 22, the protective film 20 (base material) The types of layer 21, easy-adhesive layer 22) and adhesive layer 41 are adjusted. The haze of the polarizing plate 1 can be measured using a haze meter, and can be measured by the method described in the Examples described below.

The amount of warpage in the absorption axis direction of the polarizing plate 1 at a temperature of 25°C and a relative humidity of 55% can be -5.0% or more and not more than 5.0%, it can be -4.0% or more and not more than 4.0%, it can be -3.5% or more and not more than 3.5%. , can be above -2.0% and below 2.0%. The above-mentioned warpage amount of the polarizing plate 1 can be determined by the type and thickness of the base material layer 21, the stretching ratio of the base material layer 21, the conditions of the annealing treatment performed by the manufacturing method of the polarizing plate 1 described below, the type of the polarizing element 10 and The thickness, boron content of the polarizer 10, etc. are adjusted. The above-mentioned amount of warpage of the polarizing plate 1 in the absorption axis direction can be determined as the ratio of the amount of warping of the end portion of the polarizing plate 1 in the absorption axis direction to the length of the polarizing plate 1 in the absorption axis direction, and can be determined based on the following The measurement was carried out according to the method described in the examples.

The amount of warpage in the absorption axis direction of the polarizing plate 1 is within the above range. Usually, the polarizing plate 1 is manufactured in a strip shape, so the protective film 20 used for the polarizing plate 1 is also prepared in a strip shape. The long protective film is rolled into a roll for storage and transportation. In order to prevent the protective films from adhering to each other in the roll, an easy-adhesion layer with a large haze may be provided. With such ease The protective film of the next layer has fine unevenness on the surface of the easy-to-adhere layer side, so when it is made into a roll, the base material layer of the overlapping protective film is easily deformed by the unevenness caused by the easy-to-adhesion layer. When the protective film in which the base material layer is deformed is laminated on the polarizer 10 , surface defects (indentations) may occur on the polarizer 1 . In this embodiment, as will be described later, the laminated film having the base material layer and the easy-adhesive layer is annealed to reduce the deformation of the base material layer caused by forming the laminated film into a roll, etc., and uses a smooth The protective film 20 is formed to obtain the polarizing plate 1 . Therefore, surface defects occurring in the polarizing plate 1 can be suppressed. On the other hand, when the protective film 20 obtained by annealing the laminated film is laminated on the polarizer 10, it may become a polarizing plate with a large absolute value of the amount of warpage. As will be described later, the polarizing plate 1 of this embodiment has the protective film 20 obtained by adjusting the conditions of the annealing process, etc., so that the absolute value of the amount of warpage in the absorption axis direction can be reduced as described above.

The polarizing plate 1 further has a haze within the above-mentioned range, and as will be described later, the haze of the easily adhesive layer 22 is 3% or more. As mentioned above, before and after the annealing treatment of the laminated film, the change in the haze of the easy-adhesion layer is essentially zero (to a negligible extent), so the haze of the easy-adhesion layer 22 can be regarded as changing in the laminated film. Medium haze for the easy-to-adhere layer. As mentioned above, a laminated film with a relatively high haze as an easy-to-adhere layer can inhibit adhesion. Accordingly, the polarizing plate 1 in which the haze of the easy-adhesion layer 22 is in the above-mentioned range can be said to have the protective film 20 using a laminated film that effectively suppresses blocking. In addition, in the polarizing plate 1, since the adhesive layer 41 fully penetrates into the fine unevenness formed on the surface of the protective film 20 by the easy-adhesive layer 22, it is presumed that the haze of the polarizing plate 1 becomes smaller and the haze can be obtained. Suppressed polarizing plate 1.

The polarizing plate 1 may have a square shape in plan view, for example, preferably a square shape with long sides and short sides, and more preferably a rectangular shape. The entire polarizing plate 1 or one or more of the layers constituting the polarizing plate 1 may be rounded at the corners, chamfered at the end, or perforated.

The thickness of the polarizing plate 1 is not particularly limited, but is preferably 40 μm or less, more preferably 30 μm or less. The thickness of the polarizing plate 1 is usually 10 μm or more. By setting the thickness of the polarizing plate 1 within the above range, the polarizing plate 1 can be made thinner.

The details of each layer constituting the polarizing plate 1 will be described below.

(protective film)

The protective film 20 is provided on one or both sides of the polarizer 10 and has the function of protecting the surface of the polarizer 10 . The protective film 20 has a base material layer 21 and an easy-adhesion layer 22 . The base material layer 21 and the easy-adhesive layer 22 are usually in direct contact. The easy-adhesive layer 22 is usually provided on one side of the base material layer 21, but may also be provided on both sides.

The thickness of the protective film 20 is not less than 8 μm and not more than 30 μm, preferably not less than 10 μm and not more than 28 μm, and may be not less than 15 μm and not more than 25 μm.

(Substrate layer)

The base material layer 21 constituting the protective film 20 provides mechanical strength to the protective film 20 and has the function of protecting the polarizer 10 .

The thickness of the base material layer 21 is preferably 30 μm or less. The thickness of the base material layer 21 may be 8 μm or more, may be 10 μm or more, may be 15 μm or more, and is usually 25 μm or less, and may be 20 μm or less. When the thickness of the base material layer 21 is within the above range, it becomes easy to obtain the polarizing plate 1 in which the absolute value of the amount of warpage in the absorption axis direction is reduced. In addition, when the thickness of the base material layer 21 becomes smaller, as described above, when the laminated film used is made into a roll to obtain the protective film 20, deformation easily occurs in the base material layer of the laminated film. As mentioned above, before and after the annealing treatment of the laminated film, the change in the thickness of the base material layer can be regarded as substantially zero (as small as a negligible degree). Therefore, when the thickness of the base material layer 21 is within the above range, it means that the protective film 20 is obtained from a laminated film that is easily deformed in the base material layer. In the polarizing plate 1 of this embodiment, even when the protective film 20 obtained from such a laminated film is used, surface defects can be suppressed favorably.

For example, a resin film excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, stretchability, etc. can be used for the base material layer 21 . The resin film may be a thermoplastic resin film. Specific examples of such resins include: cellulose-based resins such as cellulose triacetate; polyester-based resins such as polyethylene terephthalate and polyethylene naphthalate; polyether-based resins; polyurethane-based resins; Polyamide-based resins; polycarbonate-based resins; polyamide-based resins such as nylon and aromatic polyamide; polyimide-based resins; polyolefin-based resins such as polyethylene, polypropylene, and ethylene/propylene copolymers; with ring systems and cyclic polyolefin-based resins with norzene structures (also known as norzene-based resins); (meth)acrylic resins; polyarylate-based resins; polystyrene-based resins; polyvinyl alcohol-based resins, and A mixture of these.

A resin film composed of (meth)acrylic resin can be suitably used for the base material layer 21 . The (meth)acrylic resin is preferably polymethylmethacrylate resin.

The resin film constituting the base material layer 21 may be a uniaxially stretched film or a biaxially stretched film, with the biaxially stretched film being preferred.

(Easy adhesive layer)

The easy-adhesion layer 22 constituting the protective film 20 can improve the adhesion to the adhesive layer 41 used to bond the protective film 20 and the polarizer 10, and can improve the bonding between the protective film 20 and the polarizer 10 in the polarizer 1. Then sex. Therefore, the easy-adhesion layer 22 is usually provided on the surface of the base material layer 21 so as to constitute the surface of the protective film 20 on the polarizer 10 side.

The haze of the easy-adhesive layer 22 is 3% or more. The haze of the easy-adhesive layer 22 may be more than 4%, may be more than 5%, may be more than 8%, may be more than 10%, usually less than 30%, may be less than 25%, may be 20% the following. The haze of the easy-adhesive layer 22 can be adjusted according to the type and thickness of the easy-adhesive layer 20 , the content of the filler contained in the easy-adhesive layer 20 , etc. The haze system of the easy-adhesive layer 22 can be obtained by The haze of the protective film 20 is determined by subtracting the haze of the base material layer 21 and can be measured by the method described in the Examples described below. The haze of the protective film 20 and the base material layer 21 can be measured using a haze meter.

The haze of the easily adhesive layer 22 is considered to be substantially unchanged before and after the annealing treatment of the laminated film (described later) used to obtain the protective film 20, so it can be regarded as the haze of the easily adhesive layer in the laminated film. Accordingly, as described above, the protective film 20 included in the polarizing plate 1 can be considered to be obtained from a laminated film that can effectively suppress adhesion.

The thickness of the easy-adhesive layer 22 is preferably between 70nm and 800nm, and can be 80nm and 750nm, 100nm and 700nm, 200nm and 600nm, 280nm and 550nm, and 290nm and 500nm. . When the thickness of the easily adhesive layer 22 is within the above range, it becomes easy to adjust the haze of the easily adhesive layer 22 to the above range, and when the polarizing plate 1 is produced, it becomes easy to adjust the haze of the polarizing plate 1 to the above range. In addition, it becomes easy to suppress the discoloration of the polarizing plate 1 in the wet heat durability test. When the resin contained in the easy-adhesive layer 22 has water affinity, if the thickness of the easy-adhesive layer 22 exceeds 800 nm, the polarizing plate (especially the polarizing element containing polyvinyl alcohol-based resin) will be easily discolored according to the wet heat durability test. . The thickness of the easy-adhesive layer 22 refers to the thickness of the resin portion. As described later, when resin and filler are included, it means the thickness of the resin layer of the easy-adhesive layer 22 .

The easy-adhesive layer 22 preferably contains resin and filler. The resin contained in the easily adhesive layer 22 can be cross-linked. Examples of the resin include urethane resin, (meth)acrylic resin, polyester resin, and the like. Examples of resins contained in the easily adhesive layer 22 include polyester urethane resins, polyether urethane resins, or mixtures of these resins. However, polyester urethane resins are included. Resin is preferred. The polyester urethane resin is a urethane resin having an ester bond in the main chain of the molecule. Polyether urethane resin is a urethane resin having an ether bond in the main chain of the molecule.

The filler contained in the easy-adhesive layer 22 may be an inorganic filler or an organic filler. Examples of inorganic fillers include: inorganic oxides such as silica, titanium oxide, aluminum oxide, and zirconium oxide; calcium carbonate, talc, clay, fired kaolin, fired calcium silicate, hydrated calcium silicate, aluminum silicate, and silicic acid. Magnesium, calcium phosphate, etc. Examples of organic fillers include silicone resin, fluororesin, acrylic resin, and the like. Among these, silicon oxide is preferred, and colloidal silicon oxide is more preferred.

The average primary particle diameter of the filler may be, for example, 1 nm to 200 nm, 5 nm to 150 nm, 10 nm to 100 nm, 15 nm to 80 nm, or 20 nm to 50 nm. The average primary particle size of the filler can be measured, for example, by the BET method.

When the easy-adhesive layer 22 contains a resin and a filler, the content of the filler may be 0.3 to 10 parts by mass, 0.5 to 8 parts by mass, or 1.0 to 6 parts by mass relative to 100 parts by mass of the resin. parts or less, and may be 1.5 parts by mass or more and 5 parts by mass or less.

The easily adhesive layer 22 can be formed using an easily adhesive composition. The easy-adhesion composition may include resin, filler, cross-linking agent, alkali component, solvent, etc., and is preferably a composition in which resin is dissolved or dispersed in a solvent. The easy-adhesion composition may include monomers and polymerization initiators used to form the resin to replace the resin.

唑啉基、環氧基、或碳二亞胺基等之交聯劑。 The crosslinking agent only needs to be one that can react with the crosslinkable functional group of the resin component. When the resin component is urethane resin having cross-linkable functional groups such as carboxyl groups, it is possible to use urethane resin containing amine groups,

Cross-linking agents such as oxazoline-based, epoxy-based, or carbodiimide-based.

Examples of the base component include ammonia, amine compounds (primary amine, secondary amine, tertiary amine, etc.), hydrazine compounds, imidazole compounds, or imidazoline compounds.

Examples of the solvent system include water or water-soluble solvents. Examples of water-soluble solvents include: methanol, ethanol, isopropyl alcohol, acetone, tetrahydrofuran, N-methylpyrrolidone, dimethylstyrene, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, etc. . The preferred solvent is water.

The easily-adhesive layer can be formed by applying an easily-adhesive composition to the surface of the base layer facing the polarizer to form a coating layer, and drying the coating layer. Examples of methods for coating the easy-adhesion composition include: die-slit coater, notch wheel coater, reverse roller coater, gravure coater, rod coater, wire bar coater, and doctor blade Coating methods using applicators, air knife applicators, etc. The coated easy-adhesive composition can be dried using, for example, a hot air dryer or an infrared dryer. When the easy-adhesive composition contains monomers and polymerization initiators used to form the resin component, as long as the coating layer of the easy-adhesive composition is dried and hardened, an aging step is provided as needed, thereby forming Easy to apply layers.

(Polarized parts)

Polarizers have the function of selectively transmitting linearly polarized light from non-polarized light such as natural light.

The polarizer may be a film containing polyvinyl alcohol-based resin and boron (hereinafter sometimes referred to as "PVA-based polarizing film"), or a composition containing a compound with absorption anisotropy and liquid crystallinity coated on A liquid crystal polarizer formed of a base film (hereinafter, sometimes referred to as "liquid crystal polarizing film"). The compound with absorption anisotropy and liquid crystallinity may be a mixture of a pigment with absorption anisotropy and a compound with liquid crystallinity, or may be a pigment with absorption anisotropy and liquid crystallinity.

The polarizer is preferably PVA polarizing film. PVA-based polarizing films are preferably stretched films with adsorbed dichroic pigments. When a dichroic pigment is dispersed in a polymer chain (polyvinyl alcohol-based resin chain) that generates anisotropy by stretching, coloring is visible from a certain direction, and is almost colorless when viewed from a direction perpendicular to it.

In addition to the stretched film obtained by adsorbing and stretching a dichroic dye on a monomer polyvinyl alcohol-based resin film (hereinafter sometimes referred to as a "PVA resin film"), the PVA-based polarizing film may also be, for example, As described in Japanese Patent Application Laid-Open No. 2012-73563, a polyvinyl alcohol-based resin layer (hereinafter sometimes referred to as "PVA resin") is provided on a base film (thermoplastic resin film) such as an ester-based thermoplastic resin film. layer"), After the PVA resin layer and the substrate are completely stretched, the dichroic pigment is adsorbed/aligned to obtain an stretched layer. In addition, a general method for manufacturing the extension layer will be described later. When a PVA-based polarizing film is used as the stretched layer, it is manufactured using an appropriate base film (thermoplastic resin film) as described above, and then the base film (thermoplastic resin film) supports the polarizer that is the stretched layer. In a polarizing plate, a polarizer that is an extension layer that has been peeled off and removed from the base film can be assembled, or the base film can be used as a protective layer for the polarizer that is an extension layer to assemble the extension layer and the base film.

The boron content of the PVA-based polarizing film included in the polarizing plate is 2.8 mass% or more and 4.7 mass% or less. The boron content of the polarizer may be 3.0 mass% or more and 4.5 mass% or less, and may be 3.2 mass% or more and 4.3 mass% or less. When the boron content of the polarizer is within the above range, it becomes easier to reduce the absolute value of the amount of warpage of the polarizer. In addition, it becomes easy to suppress the discoloration of the polarizing plate in the moist heat durability test, and can suppress the shrinkage of the polarizer in the moist heat environment.

The boron content of the PVA-based polarizing film is the ratio of the mass of boron contained in the PVA-based polarizing film to the total mass of the PVA-based polarizing film, and can be determined based on the method described in the examples below. The boron in the PVA-based polarizing film is considered to exist in the free state of boric acid (H ₃ BO ₃ ), or in the state of a cross-linked structure formed by units of boron and polyvinyl alcohol-based resin. In this specification, as mentioned above, the boron content includes the amount of the boron atom (B) itself existing in the state of a compound. As will be described later, the boron content of the PVA-based polarizing film can be adjusted based on the amount of boric acid used in the production of the PVA-based polarizing film or the conditions for processing with boric acid.

The shrinkage force of the PVA polarizing film in the direction of the absorption axis is preferably 1.3N/2mm or more and 2.4N/2mm or less. It can be 1.5N/2mm or more and 2.1N/2mm or less. It can be 1.6N/2mm or more 2.0N/ 2mm or less. When the shrinkage force in the absorption axis direction of the PVA-based polarizing film is within the above range, it becomes easier to suppress the discoloration of the polarizing plate in the wet heat durability test. The shrinkage force of the PVA polarizing film in the direction of the absorption axis was measured on a polarizing element kept at a temperature of 80°C for 4 hours as described in the examples below. Certainly. The shrinkage force in the absorption axis direction of the PVA-based polarizing film can be adjusted according to the boron content, the type or amount of the dichroic pigment used in the polarizer, the extension ratio, etc.

The thickness of the PVA-based polarizing film is usually 30 μm or less, preferably 18 μm or less, more preferably 12 μm or less, and may be 10 μm or less, may be 9 μm or less, may be 8 μm or less, usually 1 μm or more, and may be 5 μm or more. The thickness of the PVA polarizing film can be adjusted based on the thickness and extension ratio of the PVA resin film (embryonic membrane) before stretching or the PVA resin layer before stretching. When the PVA polarizing film is an extension layer adsorbed with dichroic pigments, the thickness and extension ratio of the PVA resin layer formed on the base film can be adjusted.

The PVA polarizing film can be manufactured through the following steps: the step of uniaxially stretching the PVA resin film; the step of dyeing the PVA resin film with dichroic pigments such as iodine and adsorbing the dichroic pigment; The step of treating the PVA resin film adsorbed with the dichroic pigment with a boric acid aqueous solution; and the step of washing with water after the treatment with the boric acid aqueous solution. PVA-based resin films before uniaxial stretching can be easily obtained from the market. As will be described later, polyvinyl acetate-based resins can also be produced by known means and saponified to produce polyvinyl alcohol-based resins, and then the polyvinyl acetate-based resins can be produced. Vinyl alcohol resin is used to form a film. Film formation can be performed at the stage of polyvinyl acetate resin, and the polyvinyl acetate resin contained in the film can be saponified.

When the PVA-based polarizing film is an extension layer adsorbed with dichroic pigments, the PVA-based polarizing film can usually be produced through the following steps: coating a coating liquid containing polyvinyl alcohol-based resin on the base film, and A step of forming a laminated film of a PVA resin layer on a base film (hereinafter, sometimes referred to as a "PVA laminated film"); a step of uniaxially stretching the obtained PVA laminated film; by stretching the uniaxially stretched The PVA resin layer of the PVA laminated film is dyed with a dichroic pigment, and the dichroic pigment is adsorbed on the PVA resin layer to make a PVA-based polarizing film; the PVA resin layer adsorbed with the dichroic pigment is dissolved in boric acid. The step of treating with a boric acid aqueous solution; and the step of washing with water after being treated with a boric acid aqueous solution. The base film used to form the PVA-based polarizing film can also be used as a protective layer on the PVA-based polarizing film. If necessary, the base film can also be peeled and removed from the PVA-based polarizing film. Examples of the material and thickness of the base film include the materials and thickness of the base layer constituting the protective film.

Polyvinyl alcohol-based resin is obtained by saponifying polyvinyl acetate-based resin. As the polyvinyl acetate resin, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, copolymers of vinyl acetate and other monomers copolymerizable therewith can also be used. Other monosystems that can be copolymerized with vinyl acetate include, for example, unsaturated carboxylic acid compounds, olefin compounds, vinyl ether compounds, unsaturated styrene compounds, and (meth)acrylates with ammonium groups. Amine compounds, etc. In this specification, (meth)acrylic acid means at least one of acrylic acid and methacrylic acid. The same applies to the (meth)acrylyl group and the like.

The saponification degree of the polyvinyl alcohol-based resin is usually 85 mol% or more and 100 mol% or less, preferably 98 mol% or more. The polyvinyl alcohol-based resin can be modified, and aldehyde-modified polyvinyl formaldehyde, polyvinyl acetal, etc. can also be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually from 1,000 to 10,000, preferably from 1,500 to 5,000.

As the dichroic dye, iodine or organic dyes can be used, but iodine is preferably used. When using iodine as a dichroic dye, a polyvinyl alcohol-based resin film or a PVA laminated film including a base film and a PVA resin layer is usually immersed in a dyeing bath containing iodine and iodide, and the polyvinyl alcohol-based resin film is The resin is dyed with iodine. Examples of iodide compounds include potassium iodide, zinc iodide, etc., with potassium iodide being preferred. The content of iodine in the dyeing bath is 0.003 to 1 part by mass per 100 parts by mass of water. The content of iodide is 0.15 to 20 parts by mass per 100 parts by mass of water. In addition, the temperature of the dyeing bath can be about 10 to 45°C.

In particular, in the step of treating a PVA resin film having iodine adsorbed as a dichroic dye or a PVA laminated film including a PVA resin layer and a base film with a boric acid aqueous solution, the PVA resin having the dichroic dye adsorbed is usually The film or PVA laminated film is immersed in a boric acid aqueous solution (crosslinking bath). The boric acid source contained in the boric acid aqueous solution is a boron compound such as boric acid or borax. Cross-linking agents such as glyoxal and glutaraldehyde can also be used with boron compounds. The solvent of the boric acid aqueous solution may be water, but may further include an organic solvent that is compatible with water.

The boron content of the PVA polarizing film can be controlled by adjusting the conditions of the step of treating the PVA resin film adsorbed with the dichroic pigment or the PVA resin layer with a boric acid aqueous solution. For example, the boron content of the PVA polarizing film can be adjusted by changing the concentration/amount of boric acid in the boric acid aqueous solution, changing the temperature of the boric acid aqueous solution, or changing the immersion time in the boric acid aqueous solution. Appropriate preliminary experiments can also be performed to derive the conditions for the PVA-based polarizing film to have a desired boron content. In order to adjust the boron content of the PVA-based polarizing film, it is better to set the concentration of boric acid in the boric acid aqueous solution to 2.0 to 6.5 parts by mass per 100 parts by mass of water, and to appropriately adjust the immersion time in the cross-linking bath. The concentration of boric acid is set to 3.0 to 6.0 parts by mass per 100 parts by mass of water, and the immersion time of the cross-linking bath is appropriately adjusted.

The boric acid aqueous solution may further contain iodide. By adding iodide, the in-plane polarizing performance of the obtained PVA-based polarizing film can be made more uniform. Examples of the iodide compound include the compounds described above, with potassium iodide being preferred. The concentration of iodide in the boric acid aqueous solution is 0.1 to 20 parts by mass per 100 parts by mass of water.

The temperature of the boric acid aqueous solution (cross-linking bath) can usually be set to 40 to 80°C, preferably 50 to 70°C. When the temperature of the cross-linking bath is too low, the cross-linking reaction between the units of the polyvinyl alcohol-based resin and boron in the PVA resin film or PVA resin layer tends to be insufficient. On the other hand, when the temperature of the cross-linking bath is too high, In the cross-linking bath, it is easy to cause the PVA resin film or PVA laminated film to break, and the processing stability is significantly reduced. The immersion time in the cross-linking bath is usually 10 to 600 seconds, preferably 60 to 420 seconds, more preferably 90 to 300 seconds.

The uniaxial stretching of the PVA resin film or PVA laminated film can be carried out before dyeing, or during dyeing, or in the step of treating with boric acid aqueous solution after dyeing, or in multiple stages of these. Perform uniaxial extension. The PVA resin film or PVA laminated film system can be uniaxially stretched in the MD direction (film conveying direction). In this case, the uniaxial stretching can be performed between rollers with different peripheral speeds, or a hot roller can be used for uniaxial stretching. In addition, the PVA resin film or the PVA laminated film is uniaxially stretched in the TD direction (the direction perpendicular to the film conveyance direction). In this case, a so-called tenter method can be used. In addition, the above-mentioned stretching may be dry stretching in which stretching is performed in the air, or wet stretching in which a PVA resin film or PVA laminated film is stretched in a swollen state using a solvent. In order to express the performance of the polarizing element, the extension ratio is 3.0 times or more, preferably 3.5 times or more, and 4.0 times or more is particularly preferred. The upper limit of the stretch ratio is not particularly limited, but from the viewpoint of suppressing cracking, etc., it is preferably 8.0 times or less.

The liquid crystal polarizing film can be a composition containing a pigment with liquid crystallinity and absorption anisotropy, or a liquid crystal compound containing a pigment with absorption anisotropy and a polymerizable liquid crystal compound other than the pigment, which can be coated on the base film. Obtained from things. Examples of the base film include the material and thickness of the base layer constituting the protective film described above. Examples of a film system including a liquid crystalline polarizing layer include the polarizing layer described in Japanese Patent Application Laid-Open No. 2013-33249 and the like.

The liquid crystal compound only needs to have the property of displaying a liquid crystal state. In particular, it is preferable to have a higher-order alignment state such as a smectic type because it can exhibit high polarizing performance. The liquid crystal compound is preferably a polymerizable liquid crystal compound. The polymerizable liquid crystal compound is a liquid crystal compound having a polymerizable functional group.

Pigment systems with absorption anisotropy include dichroic pigments. The dichroic dye may have liquid crystallinity or may have a polymerizable functional group. The dichroic dye can be aligned by the liquid crystallinity of the dichroic dye itself, or can be aligned together with a liquid crystal compound to exhibit dichroism. Any compound contained in the composition for forming the liquid crystal polarizing layer preferably has a polymerizable functional group. The above composition system may further include initiators, solvents, dispersants, leveling agents, stabilizers, surfactants, cross-linking agents, silane coupling agents, etc.

The liquid crystal polarizing film system can be manufactured by coating the above composition on the alignment film to form a liquid crystal polarizing film. Compared with PVA-based polarizing films, liquid crystal polarizing films can be formed to a thinner thickness. The thickness of the liquid crystal polarizing film is, for example, 0.5 μm or more and 10 μm or less, and may be 1 μm or more and 5 μm or less.

The alignment film system can be produced, for example, by applying an alignment film-forming composition on a base film and imparting alignment properties by rubbing, polarized light irradiation, or the like. In addition to the alignment agent, the alignment film forming composition system may also include solvents, cross-linking agents, initiators, dispersants, leveling agents, silane coupling agents, etc. Examples of alignment agents that can be used include polyvinyl alcohols, polyacrylates, polyamides, and polyimides. When using a photoalignment agent, it is better to use an alignment agent containing a cinnamate group.

The weight average molecular weight of the polymer system used as the aligning agent can be from 10,000 to 1,000,000. The thickness of the alignment film is preferably from 5 nm to 10,000 nm. In particular, the thickness is preferably from 10 nm to 500 nm because the alignment restricting force can be fully expressed.

The liquid crystal polarizing film with the base film removed by peeling can be assembled in the polarizing plate, or the base film can be used as a protective layer of the liquid crystal polarizing film to assemble the liquid crystal polarizing film and the base material layer.

(adhesive layer)

The adhesive layer 41 can be formed of an adhesive composition. The adhesive composition used to form the adhesive layer 41 is an adhesive other than a pressure sensitive adhesive (adhesive), and examples thereof include For example: water-based adhesive, active energy ray hardening adhesive. The adhesive layer 41 is preferably a hardened layer of water-based adhesive.

Examples of water-based adhesives include adhesives in which a water-soluble resin is dissolved or dispersed in water. Examples of water-soluble resins include polyacrylamide-based resins, polyvinyl alcohol (PVA)-based resins, and vinyl alcohol-based resins such as ethylene-vinyl alcohol copolymers and (meth)acrylic acid or its anhydride-vinyl alcohol copolymers. ; Carboxy vinyl ester resin; polyvinylpyrrolidone; starch; sodium alginate; polyethylene oxide resin, etc.

The water-based adhesive preferably contains PVA-based resin. From the viewpoint of adhesiveness, the average polymerization degree of the PVA-based resin contained in the water-based adhesive is preferably about 100 to 5,500, more preferably 1,000 to 4,500. From the viewpoint of adhesion, the average degree of saponification is preferably 85 mol% to 100 mol%, more preferably 90 mol% to 100 mol%.

The PVA-based resin contained in the water-based adhesive preferably contains an acetyl acetyl group. A PVA-based resin containing an acetyl acetyl group can be obtained, for example, by reacting a PVA-based resin and diketene by any method. The acetyl acetyl group modification degree of the PVA-based resin containing an acetyl acetyl group is typically 0.1 mol% or more, preferably 0.1 mol% or more and 20 mol% or less.

Water-based adhesives can contain cross-linking agents as needed. As the cross-linking agent, a known cross-linking agent can be used. Examples include water-soluble epoxy compounds, dialdehyde compounds, isocyanate compounds, and the like.

The water-based adhesive may also contain an organic solvent. In terms of miscibility with water, alcohols are preferred as organic solvents, and methanol or ethanol is more preferred among alcohols.

The water-based adhesive may contain an antioxidant; at least one urea-based compound selected from the group consisting of urea, urea derivatives, thiourea, and thiourea derivatives.

The resin concentration of the water-based adhesive is preferably not less than 0.1% by weight and not more than 15% by weight, more preferably not less than 0.5% by weight and not more than 10% by weight. The solid content concentration of the water-based adhesive is preferably 10 mass% or more and 50 mass% or less, and may be 20 mass% or more and 40 mass% or less.

The drying method when using a water-based adhesive is not particularly limited. For example, a method of drying using a hot air dryer or an infrared dryer can be used.

Examples of active energy ray-curable adhesives include solvent-free active energy ray-curable adhesives containing a curable compound that is cured by irradiation with active energy rays such as ultraviolet light, visible light, electron rays, and X-rays. By using solvent-free active energy ray-hardening adhesive, the adhesion between layers can be improved.

In order to exhibit good adhesion, the active energy ray curable adhesive preferably contains any one or both of a cationic polymerizable curable compound and a radical polymerizable curable compound. The active energy ray curable adhesive may further contain a cationic polymerization initiator such as a photocationic polymerization initiator or a radical polymerization initiator for starting the curing reaction of the curable compound.

The thickness of the adhesive layer 41 is preferably not less than 10 nm and not more than 200 nm, more preferably not less than 20 nm and not more than 150 nm, and can be not less than 20 nm and not more than 100 nm.

(Manufacturing method of polarizing plate)

FIG. 2 is a cross-sectional view schematically showing the manufacturing steps of the polarizing plate according to one embodiment of the present invention.

The manufacturing method of the polarizing plate of this embodiment may be to manufacture the above-mentioned polarizing plate 1 , or may be to manufacture a polarizing plate other than the above-mentioned polarizing plate 1 . The polarizing plate 1 may include the polarizer 10, the adhesive layer 41, and the protective film 20 in this order. The polarizing plate 1, polarizing element 10, adhesive layer 41, and protective film 20 are as described above.

The manufacturing method of polarizing plate 1 includes the following steps:

Step (a) is to prepare the laminated film 120 having the base material layer 121 and the easy-adhesive layer 122 formed on the base material layer 121 (Fig. 2 (a));

In step (b), the laminated film 120 is annealed to obtain the protective film 20 (Fig. 2 (b)).

Step (c) is to bond the polarizer 10 on the easy-adhesive layer 122 side of the protective film 20 via the adhesive composition used to form the adhesive layer 41 (Fig. 2(c)); wherein,

The haze of the easy-adhesive layer 122 in the laminated film 120 is 3% or more,

The haze of the polarizing plate 1 is 0.5% or less.

(step (a))

The above-mentioned step (a) is a step of preparing the laminated film 120 having the base material layer 121 and the easy-adhesive layer 122. The laminated film 120 becomes the protective film 20 of the polarizing plate 1 through the annealing process in step (b).

Step (a) may include the step of forming the easy-adhesive layer 122 on the base material layer 121 . The step of forming the easy-adhesive layer 122 may include: the step of coating the easy-adhesive composition for forming the easy-adhesive layer 122 on the base material layer 121 to form a coating layer, the step of drying the coating layer, and the step of drying the The coating layer is subjected to aging steps, etc. The easily adhesive composition, the coating method of the easy adhesive composition, and the drying method of the coating layer include the compositions and methods described for the easily adhesive layer 22 of the protective film.

The haze of the easy-adhesive layer 122 of the laminated film 120 prepared in the above step (a) is 3% or more. The laminated film 120 in which the haze of the easily adhesive layer 122 is in the above range is presumed to have sufficient fine unevenness formed on the surface of the laminated film 120 on the side where the easily adhesive layer 122 is formed in order to suppress adhesion. Therefore, when the laminated film 120 is rolled into a roll shape, the occurrence of blocking can be effectively suppressed. The details of the laminated film 120 will be described later.

(step (b))

The above step (b) is a step in which the laminated film 120 is annealed (heated) to obtain the protective film 20 . By the annealing treatment performed in step (b), the protective film 20 can be obtained in which the deformation of the base material layer 121 caused by forming the laminated film 120 into a roll or the like has been smoothed. This can prevent surface defects (indentations) from occurring in the polarizing plate 1 obtained through step (c).

The base material layer 121 in the laminated film 120 that is annealed in step (b) is preferably a biaxially stretched film stretched in the first direction and the second direction as described below. The stretching ratio in the first direction is the same as that in the second direction. The ratio of the stretching ratio in the direction (first direction/second direction) (hereinafter, sometimes referred to as "stretching ratio") is 0.70 or more and 1.00 or less. The stretch ratio of the base material layer 121 in the laminated film 120 may be 0.75 or more and 1.00 or less, may be 0.80 or more and 0.95 or less, or may be 0.82 or more and 0.90 or less.

In step (b), it is preferable to perform annealing treatment on the laminated film 120 having the above-mentioned stretching ratio so that the shrinkage ratio in the second direction becomes 0.30% or less. In the annealing treatment of step (b), the shrinkage rate in the second direction of the laminated film 120 may be 0.25% or less, may be 0.20% or less, may be 0.16% or less, may be 0.10% or less, and is usually more than 0.03%. , can be above 0.05%. The shrinkage rate in the second direction of the laminated film 120 can be adjusted according to the type of the laminated film 120, the type and thickness of the base material layer 121 of the laminated film 120, the temperature of the annealing treatment, and the like. The above shrinkage rate assumes that the length of the laminated film 120 in the second direction before annealing is L1 [mm], and the length of the laminated film 120 (protective film 20) after the annealing in the second direction is L2 [mm]. can be calculated according to the following formula.

Shrinkage rate [%]=(L1-L2/L1)×100

The laminated film 120 having the above extension ratio is annealed so that the shrinkage ratio in the second direction falls within the above range, so that the absorption axis of the polarizer 10 in step (c) below is aligned with the first direction of the laminated film. The angle formed is between -20° and below 20°, and the polarizer 10 is attached to the protective The protective film 20 can thereby reduce the absolute value of the amount of warpage in the absorption axis direction of the polarizing plate 1 obtained in step (c).

The temperature of the annealing treatment in step (b) is preferably 75°C or more and 105°C or less. It can be 80°C or more and 100°C or less, and it can be 85°C or more and 95°C or less. By performing the annealing treatment at the above temperature, it becomes easy to reduce the absolute value of the amount of warpage in the absorption axis direction of the polarizing plate 1 obtained through step (c).

The annealing treatment can be performed using a device that can heat the laminated film 120 at a predetermined temperature. The device system can be listed as: heating oven, hot air circulation oven, infrared heating furnace, vacuum oven, heating plate, etc. Preferably, it is a heating oven, hot air circulation oven, infrared heating furnace, and more preferably a hot air circulation oven and infrared heating. furnace.

(step (c))

Step (c) is a step of bonding the protective film 20 and the polarizer 10 via the adhesive composition for forming the adhesive layer 41 . Step (c) is, for example, applying an adhesive composition to the easy-adhesive layer 22 side of the protective film 20 and/or the polarizer 10, and laminating the protective film 20 and the polarizer 10 via the adhesive composition, or, protecting the After the adhesive composition flows between the easily adhesive layer 22 of the film 20 and the polarizer 10, the adhesive composition is hardened. It is preferable that the adhesive flows into the surface irregularities on the easy-adhesive layer 22 side of the protective film 20 and adjusts the solid content and/or viscosity of the adhesive composition so that the haze becomes 0.5 when used as the polarizing plate 1 % in the following manner. After the adhesive composition is hardened, a step of aging may be provided.

The adhesive composition may also be a water-based adhesive. At this time, step (c) preferably includes a step of laminating the protective film 20 and the polarizer 10 via a water-based adhesive, and a step of hardening the water-based adhesive to form the adhesive layer 41 . Methods for hardening water-based adhesives include water-based adhesives. Drying processing method. The drying treatment can be performed, for example, by drying the water-based adhesive at a temperature of 50 to 100° C. for 0.5 to 10 minutes. After the drying process, it may be aged for 1 to 10 days at a temperature of about 30 to 50°C, which is slightly higher than room temperature.

As described above, when the laminated film 120 having the above stretch ratio is annealed so that the shrinkage rate in the second direction falls within the above range, the polarizer 10 and the protective film 20 are preferably so that the polarizer 10 absorbs The lamination is performed so that the angle between the axis and the first direction of the laminated film becomes -20° or more and 20° or less. The angle is preferably from -10° to 10°, more preferably from -5° to 5°, and may be 0°. Thereby, the absolute value of the amount of warpage in the absorption axis direction of the polarizing plate 1 obtained in step (c) can be reduced.

(Laminated film)

The laminated film 120 has a base material layer 121 and an easy-adhesion layer 122. The easy-adhesion layer 122 is usually provided on one side of the base material layer 121, but may also be provided on both sides. The laminated film 120 becomes the protective film 20 by the above-mentioned annealing process. The base material layer 121 and the easy-adhesion layer 122 of the laminated film 120 become the base material layer 21 and the easy-adhesion layer 22 of the protective film 20 respectively.

The base material layer 121 in the laminated film 120 can be formed using the materials described for the base material layer 21 of the protective film 20 . The thickness of the base material layer 121 can be set to the same range as the thickness of the base material layer 21 .

The base material layer 121 may be a biaxially stretched film stretched in the first direction and the second direction. In the base material layer 121, the stretching ratio in the first direction is the same as the stretching ratio in the second direction, or smaller than the stretching ratio in the second direction, and the stretching ratio ratio (stretching ratio in the first direction/stretching ratio in the second direction) It is preferably within the above range.

When the base material layer 121 is a biaxially stretched film, the stretching ratio in the first direction may be 1.2 times or more and 4.0 times or less, 1.5 times or more and 3.0 times or less, or 1.8 times or more and 2.5 times or less. base material layer When 121 is a biaxially stretched film, the stretching ratio in the second direction can be 1.3 times or more and 4.0 times or less, 1.5 times or more and 3.5 times or less, or 2.0 times or more and 3.0 times or less.

The easy-adhesive layer 122 in the laminated film 120 can be formed using the materials described for the easy-adhesive layer 22 of the protective film 20 . The thickness of the easily adhesive layer 122 can be set to the same range as the thickness of the easily adhesive layer 22 . The haze of the easily adhesive layer 122 can be set to the same range as the haze of the easily adhesive layer 22 .

The static friction coefficient of the laminated film 120 is preferably 0.10 or more and 0.90 or less, and may be 0.20 or more and 0.80 or less, may be 0.30 or more and 0.75 or less, and may be 0.60 or more. By having the static friction coefficient of the laminated film 120 within the above range, the smoothness when rolling the laminated film 120 into a roll can be improved, and the occurrence of bends or wrinkles in the laminated film 120 during or after rolling can be suppressed. . When the static friction coefficient is 0.60 or more, it becomes difficult to wind up the laminated film 120. However, since the haze of the easy-adhesion layer 122 of the polarizing plate 1 of this embodiment is 3% or more, it becomes difficult to wind up the laminated film 120. Bad situation. The static friction coefficient of the laminated film 120 is determined by using the laminated film 120 with the easy-adhesive layer 122 on one side of the base material layer 121. At a temperature of 25°C and a relative humidity of 55%, the base material layer 121 of the laminated film 120 and the The easy-adhesive layers 122 of the other laminated film 120 are rubbed together and measured, and can be measured by the method described in the Examples described below.

(Optical laminated body)

FIG. 3 is a cross-sectional view schematically showing an optical laminate according to an embodiment of the present invention. The optical laminated body 2 of this embodiment includes the polarizing plate 1, the retardation body 30, and the adhesive layer 42 in this order. The optical laminated body 2 may function as a circular polarizing plate, for example. The optical laminate 2 can be used in a display device, and the adhesive layer 42 is used to bond the optical laminate 2 to a display element of the display device. The optical laminated body 2 may have a release film on the side of the adhesive layer 42 opposite to the retardation body 30 side.

The retardation body 30 contained in the optical laminate 2 may contain a liquid crystal cured layer. The phase difference body 30 is preferably laminated on one side of the polarizer 10 and has a protective film only on one side of the polarizer 10 20, for example, as shown in FIG. 3 , the polarizer 10 may be provided with a retardation body 30 on the side opposite to the protective film 20 side. At this time, it is preferable that the polarizer 10 and the retardation body 30 are laminated via the first bonding layer 43 . The first bonding layer 43 can be directly in contact with a later-described retardation layer included in the polarizer 10 and the retardation body 30 . The first bonding layer 43 is an adhesive layer or an adhesive layer.

The retardation body 30 includes one or more retardation layers, and the retardation layer may also include a liquid crystal hardened layer. When the retardation body 30 includes two or more retardation layers, the two or more retardation layers are preferably laminated via a bonding layer. The retardation body 30 may be a laminated body in which the first retardation layer 31, the second bonding layer 33, and the second retardation layer 32 are sequentially laminated, as shown in FIG. 3, for example. At this time, at least one of the first retardation layer 31 and the second retardation layer 32 preferably includes a liquid crystal hardened layer, and both of them may include a liquid crystal hardened layer. The second bonding layer 33 is an adhesive layer or an adhesive layer.

The first retardation layer 31 may have an alignment layer and a liquid crystal hardened layer. The first retardation layer 31 may have an overcoat layer that supports and protects the surface of the liquid crystal hardened layer or alignment layer, an alignment layer, a base film of the liquid crystal alignment layer, etc. The second retardation layer 32 may have an alignment layer and a liquid crystal hardened layer. The second retardation layer 32 may have an overcoat layer that supports and protects the surface of the liquid crystal hardened layer or the alignment layer, an alignment layer, a base film of the liquid crystal alignment layer, etc.

When the retardation body 30 has the first retardation layer 31 and the second retardation layer 32, the combination of the first retardation layer 31 and the second retardation layer 32 may include, for example: [i] Giving a phase difference of λ/4 A combination of a retardation layer (λ/4 layer) and a retardation layer imparting a phase difference of λ/2 (λ/2 layer), or [ii] a phase difference layer imparting a phase difference of λ/4 (λ/4 layer) and the combination of positive C layer, etc. The first retardation layer 31 and the second retardation layer 32 may have positive wavelength dispersion or reverse wavelength dispersion. The λ/4 layer may be a λ/4 layer with reverse wavelength dispersion. When the retardation body 30 in the polarizing plate 2 includes a λ/4 layer, the absorption axis of the polarizer 10 and the λ/4 layer The angle formed by the slow axis can be 45°±10°. Thereby, the polarizing plate 2 has an anti-reflection function and can function as a circular polarizing plate.

The optical laminate 2 can be obtained by forming the adhesive layer 42 on the polarizing plate 1 . The details of each layer constituting the optical laminated body 2 will be described below.

(Phase difference body)

The phase difference system includes a liquid crystal hardened layer, which is a layer that imparts phase difference to the polarizing plate. The retardation body preferably has one or more retardation layers including a liquid crystal hardened layer. When the retardation body includes two or more retardation layers, as long as at least one retardation layer contains a liquid crystal hardened layer, the remaining retardation layers can be formed by stretching films. When the retardation body includes two or more retardation layers, the retardation body preferably has a bonding layer for bonding these layers.

The thickness of the retardation body is, for example, 0.1 μm or more and 50 μm or less, preferably 0.5 μm or more and 30 μm or less, more preferably 1 μm or more and 10 μm or less.

(Phase difference layer (first phase difference layer, second phase difference layer))

The retardation layer (first retardation layer, second retardation layer) contained in the retardation body may be formed of a resin film exemplified as a material of the base material layer constituting the protective film, or may be formed of a liquid crystal cured layer. The liquid crystal cured layer is preferably a layer obtained by polymerizing and curing a polymerizable liquid crystal compound. As mentioned above, the first retardation layer 31 and the second retardation layer 32 may include, in addition to the liquid crystal cured layer, an alignment layer, a base film, an overcoat layer, and the like.

When the liquid crystal cured layer is a layer obtained by polymerization and curing of a polymerizable liquid crystal compound, it can be formed by applying a composition containing a polymerizable liquid crystal compound to a base film and curing the composition. An alignment layer may also be formed between the base film and the coating layer. Examples of the material and thickness of the base film include the materials and thickness of the base layer constituting the protective film mentioned above.

The polymerizable liquid crystal compound is a compound having at least one polymerizable group and having liquid crystallinity. As the polymerizable liquid crystal compound, known polymerizable liquid crystal compounds can be used. The type of polymerizable liquid crystal compound used to form the liquid crystal hardened layer is not particularly limited, and rod-shaped liquid crystal compounds, disk-shaped liquid crystal compounds, and mixtures thereof can be used. The cured material layer formed by polymerizing the polymerizable liquid crystal compound is cured in a state where the polymerizable liquid crystal compound is aligned in an appropriate direction to exhibit a phase difference. When the rod-shaped polymerizable liquid crystal compound is aligned horizontally or vertically with respect to the plane direction of the optical layered body, the optical axis of the polymerizable liquid crystal compound coincides with the long axis direction of the polymerizable liquid crystal compound. When a disc-shaped polymerizable liquid crystal compound is aligned, the optical axis of the polymerizable liquid crystal compound exists in a direction orthogonal to the disc surface of the polymerizable liquid crystal compound. As rod-shaped polymerizable liquid crystal compounds, those described in Japanese Patent Application Publication No. 11-513019 (claim 1, etc.) can be suitably applied, for example. The disk-shaped polymerizable liquid crystal compound system can be suitably applied to Japanese Patent Application Laid-Open No. 2007-108732 (paragraphs [0020] to [0067], etc.) and Japanese Patent Application Laid-Open No. 2010-244038 (paragraphs [0013] to [0108] paragraphs, etc.).

The polymerizable group contained in the polymerizable liquid crystal compound means a group that participates in a polymerization reaction, and is preferably a photopolymerizable group. The photopolymerizable group refers to a group that can participate in the polymerization reaction by active radicals or acids generated from the photopolymerization initiator. Examples of polymerizable groups include: vinyl, vinyloxy, 1-chlorovinyl, isopropenyl, 4-vinylphenyl, (meth)acryloxy, oxirane, and oxetane Alkyl, styryl, allyl, etc. Among them, (meth)acryloxy group, vinyloxy group, oxirane group and oxetanyl group are preferred, and acryloxy group is more preferred. The liquid crystal property of the polymerizable liquid crystal compound can be either a thermotropic liquid crystal or a liquid crystal. When classifying thermotropic liquid crystals in terms of order, they can be either nematic liquid crystal or smectic liquid crystal. When two or more types of polymerizable liquid crystal compounds are used together to form a hardened material layer of a polymerizable liquid crystal compound, it is preferred that at least one type have two or more polymerizable groups in the molecule.

The liquid crystal cured layer is a coating film formed by applying a composition for forming a liquid crystal cured layer containing a polymerizable liquid crystal compound, a solvent, and various additives as required on an alignment layer described later, and curing the coating film ( hardening) to form a layer in which the polymerizable liquid crystal compound is polymerized and hardened. Alternatively, the composition can be applied on a base film to form a coating film, and the coating film can be stretched together with the base film and hardened to form the coating film. In addition to the above-mentioned polymerizable liquid crystal compound and solvent, the above composition may also contain a polymerization initiator, a reactive additive, a leveling agent, a polymerization inhibitor, etc. As the polymerizable liquid crystal compound, solvent, polymerization initiator, reactive additive, leveling agent, polymerization inhibitor, etc., known ones can be suitably used.

The thickness of the liquid crystal hardened layer may be 0.1 μm or more, 0.5 μm or more, or 1 μm or more, and may be 10 μm or less, 8 μm or less, 5 μm or less, or 3 μm or less.

The alignment layer has an alignment restriction force that aligns the polymerizable liquid crystal compound in a desired direction. The alignment layer can be a vertical alignment film in which the molecular axis of the polymerizable liquid crystal compound is aligned vertically with respect to the plane direction of the optical laminate, or it can be a vertical alignment film in which the molecular axis of the polymerizable liquid crystal compound is aligned horizontally with respect to the plane direction of the laminate. The horizontal alignment film may also be a tilt alignment film in which the molecular axis of the polymerizable liquid crystal compound is tilted with respect to the plane direction of the optical laminate.

The alignment layer preferably has solvent resistance such that it is not dissolved by application of a composition for forming a liquid crystal cured layer containing a polymerizable liquid crystal compound, and heat treatment for removing the solvent or aligning the polymerizable liquid crystal compound. sexual person. Examples of the alignment layer system include an alignment polymer layer formed of an alignment polymer, a photo-alignment polymer layer formed of a photo-alignment polymer, a concave-convex pattern formed by rubbing treatment on the surface of the layer, or a plurality of Groove alignment layer of trench (groove), etc.

(adhesive layer)

The adhesive layer 42 is a layer formed using an adhesive. Adhesives are those that adhere themselves to the object to show adhesion, and are also called so-called pressure-sensitive adhesives. As the adhesive, a known adhesive having excellent optical transparency can be used. Known adhesives include, for example, adhesives containing base polymers such as acrylic polymers, urethane polymers, polysiloxane polymers, and polyvinyl ethers. In addition, the adhesive may be an active energy ray-hardening adhesive, a thermosetting adhesive, or the like. Among these, an adhesive using an acrylic resin as a base polymer that is excellent in transparency, adhesion, re-peelability (reworkability), weather resistance, heat resistance, etc. is suitable. The adhesive layer is preferably composed of an adhesive containing (meth)acrylic resin, a cross-linking agent, and a silane coupling agent, and may also contain other components.

The thickness of the adhesive layer 42 is not particularly limited, but is preferably 5 μm to 300 μm, may be 10 μm to 250 μm, may be 15 μm to 100 μm, may be 20 μm to 70 μm, may be 25 μm to 50 μm.

(1st laminating layer, 2nd laminating layer)

The first bonding layer 43 and the second bonding layer 33 (hereinafter, both are sometimes collectively referred to as "laminated layers") are each independently an adhesive layer or an adhesive layer. Examples of the adhesive layer and adhesive layer include those described above.

(peeling film)

The release film system may have a base film and a release treatment layer. The base film may be a resin film. The resin film can be formed, for example, from the material that forms the above-mentioned base material layer constituting the protective film. The release treatment layer only needs to be a known release treatment layer, and examples thereof include a layer formed by applying a release agent such as a fluorine compound or a polysiloxy compound to a base film.

(display device)

The optical laminated body 2 can be used in a display device. The display device may have a display element and an optical laminate 2 laminated on the viewing side of the display element. The optical laminate 2 system can be 42 is attached to the display element. When the optical laminate 2 is provided with the polarizing plate 1 having the protective film 20 only on one side of the polarizer 10, and when the optical laminate 2 is disposed on the viewing side of the display element, it is preferable that the protective film 20 is located further than the polarizer 10. Close to the identification side. The display device is not particularly limited, and examples thereof include image display devices such as organic EL display devices, inorganic EL display devices, liquid crystal display devices, and electric light-emitting display devices. The display device can function as a touch panel. The optical laminate 2 can be used in a flexible display device having flexibility such as bending or bending.

The display device can be used as portable devices such as smartphones and tablets, televisions, digital photo frames, electronic signboards, measuring instruments or instruments, office equipment, medical equipment, electronic computers, etc., and is especially suitable for use in the future. Display devices mounted on portable devices requiring smaller sizes are required.

[Example]

Hereinafter, the present invention will be explained more specifically by showing examples and comparative examples, but the present invention is not limited to these examples.

<Production of polarizer>

(Production of polarizer a)

Prepare a polyvinyl alcohol-based resin film with a thickness of 20 μm, a polymerization degree of 2400, and a saponification degree of 99% or more. The polyvinyl alcohol-based resin film was uniaxially stretched on a hot roller to a stretch magnification of 4.1 times, maintained in a taut state, and immersed in a dyeing bath at 28°C containing 0.05 parts by mass of iodine and 5 parts by mass of potassium iodide per 100 parts by mass of water. Hit for 60 seconds.

Then, it was immersed in the 64 degreeC boric acid aqueous solution (1) containing 5.5 mass parts of boric acid and 15 mass parts of potassium iodide per 100 mass parts of water for 110 seconds. Thereafter, it was immersed in a boric acid aqueous solution (2) having a temperature of 67°C and containing 3.9 parts by mass of boric acid and 15 parts by mass of potassium iodide per 100 parts by mass of water for 30 seconds. Thereafter, the polarizer a was obtained by washing with pure water at a temperature of 10° C. and drying. The thickness, boron content, and shrinkage of polarizer a were measured according to the procedures described below. The results are shown in Tables 1 to 3.

(Production of polarizer b)

The polarizer b was produced in the same manner as the polarizer a except that the boric acid content of the boric acid aqueous solution (2) was changed to 2.3 parts by mass per 100 parts by mass of water. The thickness, boron content, and shrinkage force of the polarizer b were measured according to the procedures described below. The results are shown in Tables 1 to 3.

(Production of polarizer c)

The polarizer c was produced in the same manner as the polarizer a except that the boric acid content of the boric acid aqueous solution (2) was changed to 5.5 parts by mass per 100 parts by mass of water. The thickness, boron content, and shrinkage force of the polarizer c were measured according to the procedures described below. The results are shown in Tables 1 to 3.

(Production of polarizer d)

The polarizer d was produced in the same manner as the polarizer a except that the boric acid content of the boric acid aqueous solution (2) was changed to 1.5 parts by mass per 100 parts by mass of water. The thickness, boron content, and shrinkage force of the polarizer d were measured according to the procedures described below. The results are shown in Tables 1 to 3.

[Measurement of thickness]

The thickness of each layer of the polarizer, the laminated film described below, and the protective film is measured with a contact film thickness meter [trade name "DIGIMICRO (registered trademark) MH-15M" manufactured by Nikon Co., Ltd.]. The thickness of the easy-adhesion layer of the laminated film and the protective film is determined by the thickness of the resin layer.

[Boron content of polarizer]

Dissolve 0.2 g of polarizer in 200 g of 1.9 mass% mannitol aqueous solution. The obtained aqueous solution was titrated with 1 mol/L NaOH aqueous solution, and the boron amount (mass) was calculated by comparing the amount of NaOH solution required for neutralization with the calibration curve. The boron content of the polarizer was calculated as the calculated amount of boron relative to the mass of the polarizer.

[Measurement of shrinkage force of polarizer]

The polarizer was cut into a rectangular shape with a short side of 2 mm and a long side of 50 mm using a Supercutter (manufactured by Ogino Seiki Seisakusho Co., Ltd.) so that the absorption axis of the polarizer coincides with the long side to serve as a test piece. The shrinkage force of the test piece was measured using a thermomechanical analysis device (model TMA/6100 manufactured by SII TECHNOLOGY Co., Ltd.). This measurement was performed in the constant size mode, with the distance between the fixtures set to 10mm, the static load set to 0mN, and a SUS probe used as the jig, and carried out according to the following procedure. First, place the test piece in a room with a temperature of 20°C for a sufficient period of time. After that, the temperature setting in the room where the test piece was placed was raised from 20°C to 80°C in 10 minutes. After raising the temperature, set it to maintain the indoor temperature at 80°C. After leaving it for another 4 hours, measure the shrinkage force in the longitudinal direction (absorption axis direction) of the test piece in an environment with a temperature of 80°C.

<Production of laminated film>

(Easy to prepare the composition)

唑啉的聚合物、日本觸媒股份有限公司製，商品名：EPOCROS WS-700，固形份：25%)4.2g、1質量%之氨水2.0g、膠態氧化矽(扶桑化學工業股份有限公司製，QUARTRON PL-3，固形份：20質量%)0.42g、及純水76.6g，獲得易接著組成物。 Mixed polyester urethane (manufactured by Daiichi Industrial Pharmaceutical Co., Ltd., trade name: SUPERFLEX 210, solid content: 33%) 16.8g, cross-linking agent (containing

Polymer of oxazoline, manufactured by Nippon Shokubai Co., Ltd., trade name: EPOCROS WS-700, solid content: 25%) 4.2g, 1 mass% ammonia 2.0g, colloidal silicon oxide (Fuso Chemical Industry Co., Ltd. Prepared, QUARTRON PL-3, solid content: 20 mass%) 0.42g, and pure water 76.6g, to obtain an easy-to-adhere composition.

(Production of laminated film A)

=20.0mm、L/D=25)及衣架型T模頭(Coat hanger type T die)(寬度150mm)，在溫度280℃下熔融擠壓出屬於丙烯酸系樹脂之聚甲基丙烯酸甲酯樹脂[玻璃轉移溫度：135℃、熔融黏度：700Pa‧s(溫度270℃、剪切速度100(1/sec))]之顆粒。藉由將擠壓出的樹脂以保持於溫度110℃之冷卻輥進行冷卻，成形為厚度80μm之未延伸的丙烯酸系樹脂膜。將如此方式得到的未延伸 之丙烯酸系樹脂膜使用桌上型延伸機在長邊方向以延伸倍率2.0倍進行延伸，獲得延伸膜。 Use a single-axis extruder (

=20.0mm, L/D=25) and Coat hanger type T die (width 150mm), the polymethyl methacrylate resin, which is an acrylic resin, is melt-extruded at a temperature of 280°C [ Glass transition temperature: 135℃, melt viscosity: 700Pa‧s (temperature 270℃, shear speed 100(1/sec))] particles. The extruded resin was cooled with a cooling roll maintained at a temperature of 110° C. to form an unstretched acrylic resin film with a thickness of 80 μm. The unstretched acrylic resin film obtained in this manner was stretched in the longitudinal direction at a stretching magnification of 2.0 times using a desktop stretching machine to obtain a stretched film.

After applying the easy-adhesion composition prepared above on one surface of the stretched film using a bar coater, it was put into a hot air dryer and dried at a temperature of 100° C. for 90 seconds to obtain a stretched film with a coated film. The stretched film with the coating film was stretched in the width direction using a desktop stretching machine (stretching ratio: 2.35 times) to obtain a laminated film A having an easy-adhesion layer with a thickness of 300 nm on the surface of a base layer with a thickness of 20 μm. The obtained laminated film A was wound into a roll shape at a constant tension.

In the laminated film A, the longitudinal direction is the first direction and the width direction is the second direction. The haze and static friction coefficient of the laminated film A are measured according to the procedure described below, and the storage is evaluated. The results are shown in Tables 1 to 3.

(Production of laminated films B and C)

The conditions are the same as those of the laminated film A except that the ratio of the stretching ratio when the stretched film is obtained and the stretching ratio when the stretched film with the coating film is stretched in the width direction is changed to the stretching ratios described in Tables 1 to 3. Method: Laminated films B and C were obtained and rolled into rolls. In the laminated films B and C, the longitudinal direction is the first direction and the width direction is the second direction. The haze and static friction coefficient of laminated films B and C were measured according to the procedure described below, and storage was evaluated. The results are shown in Tables 1 to 3.

(Production of laminated films D to F)

Laminated films D to F were obtained in the same manner as laminated film A, except that the thickness of the coating film formed using the easy-adhesive composition was changed to the thicknesses listed in Tables 1 to 3, and then rolled into a roll. The haze and static friction coefficient of the laminated films D and E were measured according to the procedure described below, and the storage was evaluated. Moreover, the haze of the laminated film F was measured by the procedure mentioned later, and the storage was evaluated. The results are shown in Tables 1 to 3.

(Production of laminated film G)

The conditions are the same as those of the laminated film A except that the ratio of the stretching ratio when the stretched film is obtained and the stretching ratio when the stretched film with the coating film is stretched in the width direction is changed to the stretching ratios described in Tables 1 to 3. Method: The laminated film G is obtained and rolled into a roll shape. In the laminated film G, the longitudinal direction is the first direction and the width direction is the second direction. The haze and static friction coefficient of the laminated film G are measured according to the procedure described below, and the storage is evaluated. The results are shown in Tables 1 to 3.

(Production of laminated film H)

The ratio of the stretching ratio when the stretched film is obtained by making the longitudinal direction become the second direction and the width direction becomes the first direction, and the stretching ratio when the stretched film with the coating film is stretched in the width direction is changed to Except for the stretch ratios described in Tables 1 to 3, the laminated film H was obtained in the same manner as the laminated film A and wound into a roll. The haze and static friction coefficient of the laminated film H are measured according to the procedure described below, and the storage is evaluated. The results are shown in Tables 1 to 3.

(Production of laminated film I)

The laminated film I was obtained in the same manner as the laminated film A except that the thickness of the coating film formed using the easy-adhesion composition was changed to the thicknesses listed in Tables 1 to 3, and the film was wound into a roll. The haze and static friction coefficient of the laminated film I were measured according to the procedure described below, and the storage was evaluated. The results are shown in Tables 1 to 3.

(Production of laminated film J)

Except that the thickness of the base material layer was changed to the thickness described in Tables 1 to 3, the laminated film J was obtained in the same manner as the laminated film A and wound into a roll shape. The haze and static friction coefficient of the laminated film J were measured according to the procedure described below, and the storage was evaluated. The results are shown in Tables 1 to 3.

[Measurement of haze of easy-adhesive layer]

The laminated film was cut into a size of 40 mm × 40 mm, and the haze was measured using a haze meter HR-150 manufactured by Murakami Color Technology Research Institute Co., Ltd., which was used as the haze of the laminated film. Then, the laminated film is formed The base material layer was cut into a size of 40 mm × 40 mm, and the haze was measured using the above-mentioned haze meter, which was used as the haze of the base material layer. The haze of the easy-adhesive layer is determined by subtracting the haze of the base material layer from the haze of the laminated film.

[Measurement of static friction coefficient]

Prepare 2 laminated films for measuring the static friction coefficient. The easily bondable layer side of a laminated film is fixed on the glass plate. The base material layer side of the other laminated film was fixed to a stainless steel jig so that the contact area became 40 cm ² . Under the conditions of a temperature of 25°C and a relative humidity of 55%, the base material layer of the laminated film fixed on the glass plate is closely connected to the easy-adhesive layer of the laminated film fixed on the jig, and 200g of the laminated film is applied from the jig. In the state of load, calculate the static friction coefficient from the maximum load when moving in the horizontal direction (direction perpendicular to the load direction) at a speed of 100mm/min.

[Evaluation of safekeeping]

The laminated film rolled into a roll is stored and pulled out after a predetermined period of time. The state of the pulled out laminated film is visually observed and evaluated based on the following criteria. The evaluation results are shown in Tables 1 to 3.

A: No wrinkles, bends, or adhesion will occur in the laminated film even if it is more than 1 month after rolling.

B: Any of wrinkles, bends, or adhesion in the laminated film occurs more than 1 week and within 1 month after winding.

C: Any wrinkles, bends, or adhesion occur in the laminated film within 1 week after winding.

<Preparation of water-based adhesive>

Dissolve 3 parts by mass of carboxyl-modified polyvinyl alcohol (KURARAY Co., Ltd., trade name "KL-318") in 100 parts by mass of water, and add a polyamide epoxy additive that is a water-soluble epoxy resin to the aqueous solution. (Taoka Chemical Industry Co., Ltd., trade name "SUMIREZ RESIN (registered trademark) 650 (30), solid content concentration 30 mass % aqueous solution)" 1.5 parts by mass, and prepare a water-based adhesive.

[Examples 1 to 17, Comparative Example 1]

The laminated film shown in Tables 1 to 3 was pulled out and rolled into a roll, and annealed to obtain a protective film at a temperature and shrinkage rate shown in Tables 1 to 3. After the annealing treatment, the above-mentioned protective film was bonded to one side of the polarizer shown in Tables 1 to 3 via the aqueous adhesive prepared above, and dried to obtain a polarizing plate. In the polarizing plates of Examples 1 to 14, 16, 17 and Comparative Example 1, the absorption axis direction of the polarizing element is parallel to the long side direction (first direction) of the protective film. In the polarizing plate of Example 15, the absorption axis of the polarizing element is The axial direction is orthogonal to the width direction (first direction) of the protective film.

The shrinkage rate of the laminated film accompanying the annealing treatment and the haze and warpage amount of the polarizing plate were measured according to the procedures described below, and the indentation evaluation and wet heat durability test were performed. The results are shown in Tables 1 to 3. In addition, the thickness of the base layer of the protective film and the haze and thickness of the easy-adhesive layer are the same as the thickness of the base layer of the laminated film and the haze and thickness of the easy-adhesive layer measured above.

[Comparative example 2]

The polarizing plate was obtained in the same manner as in Example 1 except that the laminated film A without annealing was used directly as a protective film to obtain a polarizing plate. The haze and warpage of the polarizing plate were measured according to the procedures described below, and the indentation evaluation and wet heat durability test were performed. The results are shown in Tables 1 to 3.

[Measurement of Shrinkage]

While conveying the laminated film before annealing, the width-direction length of the laminated film was measured using a laser displacement meter (manufactured by KEYENCE Co., Ltd.), and this was taken as the width-direction length Lw1 [mm] of the laminated film. Then, after annealing while conveying the laminated film, the length Lw2 [mm] in the width direction of the laminated film (protective film) after the annealing treatment was measured using the above-mentioned laser displacement meter, and this was used as the width direction length of the protective film. length. From the measured length value, the shrinkage rate was calculated according to the following formula. In addition, the width direction of the laminated film was the second direction in Examples 1 to 14, 16, 17 and Comparative Example 1, and was the first direction in Example 15.

Shrinkage rate [%]=(Lw1-Lw2/Lw1)×100

[Measurement of haze of polarizing plates]

The polarizing plate was cut into a size of 40 mm × 40 mm, and the haze was measured using a haze meter HR-150 manufactured by Murakami Color Technology Research Institute Co., Ltd., which was used as the haze of the polarizing plate.

[Measurement of the amount of warpage of polarizing plates]

Place the polarizing plate in an environment with a temperature of 25°C and a relative humidity of 55% for 24 hours. The polarizing plate was cut into a rectangular shape with a length of 164 mm in the absorption axis direction and a length of 70 mm in the transmission axis direction and used as a measurement sample. Place the measurement sample on a reference plane (horizontal platform) with the concave surface facing upward, and measure the amount of lift of both ends of the measurement sample in the direction of the absorption axis (two sides parallel to the direction of the penetration axis) as the distance from the reference plane. the height. Among the two sides of the measurement sample that are parallel to the direction of the penetration axis, the measurement is performed at 5 points at the two ends, the center, and the midpoint between the two ends and the center, for a total of 10 points at 5 points on each side. Measure and average the results to obtain the warpage height [mm]. The warp height when the protective film side of the polarizing plate becomes a concave surface is taken as a positive value, and the warp height when the polarizer side of the polarizing plate becomes a concave surface is taken as a negative value. From the measured warp height and the length of the measured sample in the absorption axis direction, the amount of warp is calculated according to the following formula.

Amount of warpage [%] = (height of warpage [mm]/length of the measurement sample in the direction of the absorption axis [mm]) × 100

[Evaluation of Indentations (Surface Defects)]

Visually observe the surface of the protective film side of the polarizing plate and evaluate based on the following criteria. The results are shown in Tables 1 to 3.

A: No indentation is seen on the protective film.

B: A slight indentation is seen on the protective film.

C: Obvious indentations are seen on the protective film.

D: Very obvious indentations are seen on the protective film.

[Damp heat durability test]

(Preparation of acrylic adhesive layer)

In a reaction container equipped with a stirrer, a thermometer, a reflux cooler, a dripping device, and a nitrogen introduction pipe, 97.0 parts by mass of n-butyl acrylate, 1.0 parts by mass of acrylic acid, 0.5 parts by mass of 2-hydroxyethyl acrylate, and ethyl acetate were placed. 200 parts by mass of ester and 0.08 parts by mass of 2,2'-azobisisobutyronitrile, and the air in the reaction container was replaced with nitrogen. The reaction solution was heated to 60° C. while stirring in a nitrogen environment. After reacting for 6 hours, it was cooled to room temperature to obtain a (meth)acrylate polymer with a weight average molecular weight of 1.8 million. 100 parts by mass of this (meth)acrylate polymer (solid content conversion value; the same below) and trimethylolpropane-modified toluene diisocyanate (manufactured by TOSOH Co., Ltd., CORONATE L) as an isocyanate-based cross-linking agent were mixed. 0.30 parts by mass and 0.30 parts by mass of 3-glycidoxypropyltrimethoxysilane (KBM 403, manufactured by Shin-Etsu Chemical Industry Co., Ltd.) as a silane coupling agent were thoroughly stirred and diluted with ethyl acetate, thereby, A coating solution of the adhesive composition was obtained. After applying the above-mentioned coating solution with a thin coater on the release-treated surface of the release film (SP-PLR382190 manufactured by LINTEC Co., Ltd.) so that the thickness after drying becomes 25 μm, it is dried at a temperature of 100°C for 1 minutes to obtain an acrylic adhesive layer.

(Damp heat durability test)

The polarizing plate was cut into a size of 50 mm×50 mm, and was bonded to alkali-free glass via the acrylic adhesive layer obtained above to prepare a test piece. Place the test piece in a constant temperature and humidity device with a temperature of 60°C and a relative humidity of 95%, and let it stand for 500 hours. Observe the appearance of the polarizing plate on the test piece and evaluate it based on the following standards. The results are shown in Tables 1 to 3.

A: No discoloration was seen.

B: Slightly discolored.

C: Overall discoloration.

[Table 1]

[Table 2]

[table 3]

1:Polarizing plate

10:Polarizer

20:Protective film

21:Substrate layer

22: Easy to adhere layer

41:Adhesive layer

Claims (18)

A polarizing plate, which is provided with a polarizer, an adhesive layer, and a protective film in sequence, wherein: The protective film has a base material layer and an easy-adhesive layer laminated on the adhesive layer side of the base material layer, The haze of the aforementioned easy-adhesive layer is above 3%. The haze of the aforementioned polarizing plate is below 0.5%. At a temperature of 25°C and a relative humidity of 55%, the amount of warpage in the absorption axis direction of the polarizing plate is -5.0% or more and 5.0% or less. The polarizing plate according to claim 1, wherein the thickness of the base material layer is 30 μm or less. The polarizing plate according to claim 1 or 2, wherein the thickness of the easy-adhesive layer is 70 nm or more and 800 nm or less. The polarizing plate according to any one of claims 1 to 3, wherein the thickness of the polarizing element is 12 μm or less. The polarizing plate according to any one of claims 1 to 4, wherein the polarizing element contains polyvinyl alcohol resin, The shrinkage rate in the absorption axis direction of the polarizer at a temperature of 80°C is 1.3N/2mm or more and 2.4N/2mm or less. The polarizing plate according to any one of claims 1 to 5, wherein the polarizing element contains polyvinyl alcohol resin and boron, The boron content of the polarizer is 2.8 mass% or more and 4.7 mass% or less. The polarizing plate according to any one of claims 1 to 6, wherein the base material layer is a (meth)acrylic resin film. The polarizing plate according to any one of claims 1 to 7, wherein the easily adhesive layer contains resin and filler. The polarizing plate according to any one of claims 1 to 8, wherein the adhesive layer is a hardened layer of a water-based adhesive. The polarizing plate according to any one of claims 1 to 9, wherein the thickness of the adhesive layer is 10 nm or more and 200 nm or less. An optical laminate including the polarizing plate, the retardation body, and the adhesive layer described in any one of claims 1 to 10 in this order. A display device including the optical layered body according to claim 11. A method of manufacturing a polarizing plate. The polarizing plate is provided with a polarizer, an adhesive layer, and a protective film in sequence. The manufacturing method of the polarizing plate includes the following steps: Step (a) is to prepare a laminated film having a base material layer and an easy-adhesion layer formed on the base material layer; Step (b) is to subject the aforementioned laminated film to annealing treatment to obtain the aforementioned protective film; Step (c) is to bond the polarizer on the side of the easy-adhesive layer in front of the protective film through the adhesive composition used to form the adhesive layer; wherein, The haze of the easily adhesive layer in the laminated film is 3% or more, The haze of the aforementioned polarizing plate is less than 0.5%. The manufacturing method of a polarizing plate according to claim 13, wherein in the laminated film, the base material layer is a biaxially stretched film stretched in the first direction and the second direction, The stretching ratio in the first direction is the same as or smaller than the stretching ratio in the second direction, The ratio of the stretch ratio in the first direction to the stretch ratio in the second direction (first direction/second direction) is 0.70 or more and 1.00 or less, The aforementioned step (b) is to perform annealing treatment so that the shrinkage rate of the aforementioned laminated film in the aforementioned second direction becomes 0.30% or less, The aforementioned step (c) is to bond the polarizer and the protective film so that the angle between the absorption axis direction of the polarizer and the first direction of the laminated film becomes -20° or more and 20° or less. The manufacturing method of a polarizing plate according to claim 13 or 14, wherein the step (b) is to anneal the laminated film at a temperature of not less than 75°C and not more than 105°C. The method for manufacturing a polarizing plate according to any one of claims 13 to 15, wherein the thickness of the base material layer in the laminated film is 30 μm or less. The method for manufacturing a polarizing plate according to any one of claims 13 to 16, wherein the adhesive composition is a water-based adhesive. The manufacturing method of a polarizing plate according to any one of claims 13 to 17, wherein the polarizing element contains polyvinyl alcohol resin and boron, The boron content of the polarizer is 2.8% by mass or more and 4.7% by mass or less.

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