TW202232154A - Polarizing plate, and polarizing plate with retardation layer - Google Patents

Abstract

The present invention provides a polarizing plate which exhibits excellent adhesion and excellent followability to curved surfaces even though the polarizing plate is extremely thin. A polarizing plate according to the present invention comprises a polarizer and protective layers that are arranged on both surfaces of the polarizer; the protective layers contain an epoxy resin that has an aromatic skeleton and a diol skeleton; and the epoxy resin has a glass transition temperature of 40 DEG C or less, while having an elongation of 1.40 mm or more in a penetration test.

Description

Polarizing plate and polarizing plate with retardation layer

The present invention relates to a polarizing plate and a polarizing plate with retardation layer.

In an image display device (eg, a liquid crystal display device, an organic EL display device), a polarizing plate is usually disposed on at least one side of the display unit based on its image forming method. In recent years, the thinning and flexibility of image display devices have been continuously advanced, and there is a strong expectation for the thinning of polarizing plates. However, if the conventional thin polarizer is applied to a flexible image display device, the adhesiveness of the polarizer decreases and the compliance of the polarizer to curved surfaces decreases. prior art literature Patent Literature

Patent Document 1: Japanese Patent Laid-Open No. 2015-210474

The problem to be solved by the invention The present invention was made in order to solve the above-mentioned conventional problems, and its main object is to provide a polarizing plate excellent in adhesion and conformability to curved surfaces despite being very thin.

means of solving problems The polarizer of the present invention comprises a polarizer and a protective layer disposed on both sides of the polarizer; the protective layer comprises an epoxy resin having an aromatic skeleton and a diol skeleton, and its glass transition temperature is below 40°C; The elongation during the puncture test is 1.40mm or more. In one embodiment, the polarizer is composed of a polyvinyl alcohol-based resin film containing a dichroic substance, and the orientation function is 0.30 or less. In one Embodiment, the said protective layer consists of the hardened|cured material of the photocationic polymerization of the said epoxy resin, or the hardened|cured material of the coating film of the organic solvent solution of the said epoxy resin. In one embodiment, the total thickness of the polarizing plate is 20 µm or less. In one embodiment, the puncture strength of the polarizing plate is 300 g or more. In one Embodiment, the glass transition temperature of the said protective layer is 0 degreeC or more. In another aspect, the present invention provides a polarizing plate with retardation layer. The polarizing plate with retardation layer includes a retardation layer, the above-mentioned polarizer and the above-mentioned protective layer.

Invention effect According to the present invention, the protective layers disposed on both sides of the polarizer include epoxy resin having an aromatic skeleton and a diol skeleton, and its glass transition temperature is 40° C. or lower, whereby a very thin film with excellent adhesion can be obtained. A polarizing plate with excellent surface compliance.

A. Outline of polarizer FIG. 1 is a schematic cross-sectional view of a polarizing plate according to an embodiment of the present invention. The polarizer 100 illustrated in the figure has a polarizer 10 and protective layers 20 and 30 disposed on both sides of the polarizer 10 . When the polarizing plate 100 is applied to a liquid crystal display device, it may be arranged on the viewing side of the display unit, or may be arranged on the opposite side (back side) to the viewing side. The polarizing plate can be in the shape of a long strip or a single sheet. When the polarizing plate is in the shape of a long strip, it should be wound into a roll shape.

Representatively, the polarizing plate can have an adhesive layer as the outermost layer on one side, and can be attached to the display unit. The surface protection film and/or the carrier film can be temporarily adhered to the polarizing plate in a peelable manner as required to reinforce and/or support the polarizing plate. When the polarizing plate includes an adhesive layer, the surface of the adhesive layer is temporarily adhered with a separation piece in a releasable manner, which can protect the adhesive layer before actual use, and can roll the polarizing plate.

In the embodiment of the present invention, the protective layer contains an epoxy resin having an aromatic skeleton and a diol skeleton, and the glass transition temperature thereof is 40° C. or lower. With the above-described configuration, a polarizing plate excellent in adhesion and curved surface conformability can be realized.

The protective layer is preferably composed of a photocationic cured product of an epoxy resin having an aromatic skeleton and a diol skeleton, or a cured product of a coating film of an organic solvent solution of the epoxy resin. With the above configuration, the protective layer can be made very thin (eg, 10 µm or less). In addition, the protective layer can be directly formed on the polarizer (ie, without passing through the adhesive layer or the adhesive layer). According to the embodiment of the present invention, as described above, the protective layer is very thin and the adhesive layer or the adhesive layer can be omitted, so that the total thickness of the polarizing plate can be extremely thin. In addition, the adhesion between the polarizer and the protective layer is also excellent. The total thickness of the polarizing plate is preferably 20µm or less, preferably 15µm or less, and more preferably 12µm or less. The total thickness of the polarizing plate may be, for example, 4 µm or more.

The elongation during the puncture test of the polarizing plate is 1.40mm or more, preferably 1.60mm or more. When the elongation of the polarizing plate in the puncture test is within the above-mentioned range, a polarizing plate having excellent adhesion and excellent conformability to curved surfaces can be obtained.

In the embodiment of the present invention, the puncture strength of the polarizing plate is preferably 300g or more, more preferably 340g or more. If the puncture strength of the polarizing plate is within the above-mentioned range, a polarizing plate excellent in adhesion and curved surface compliance can be obtained.

In the embodiment of the present invention, the thickness of the polarizing plate can be extremely thin as described above. Therefore, it can be suitably applied to a flexible image display device. Preferably, the image display device has a curved shape (essentially a curved display screen), and/or is flexible or bendable. Specific examples of the image display device include a liquid crystal display device and an electroluminescence (EL) display device (for example, an organic EL display device and an inorganic EL display device). Of course, the above description does not prevent the polarizing plate of the present invention from being applied to general image display devices.

The polarizer and the protective layer are described in detail below.

B. Polarizer Any suitable polarizer can be used as the polarizer. The polarizer is composed of a PVA-based resin film containing a dichroic substance. The resin film forming the polarizer may be, for example, a single-layer resin film or a laminate of two or more layers.

Specific examples of polarizers composed of a single-layer resin film include polyvinyl alcohol (PVA)-based films, partially formalized PVA-based films, ethylene-acetic acid using dichroic substances such as iodine and dichroic dyes. Vinyl ester copolymer is a hydrophilic polymer film such as a partially saponified film, which is dyed and stretched; a polyene-based oriented film such as a dehydration-treated product of PVA or a dehydrochloric acid-treated product of polyvinyl chloride, etc. From the viewpoint of excellent optical properties, it is preferable to use a polarizer obtained by uniaxially extending a PVA-based film dyed with iodine.

The above-mentioned dyeing with iodine can be performed, for example, by immersing a PVA-based film in an aqueous iodine solution. The stretching ratio of the above-mentioned uniaxial stretching is preferably 3 to 7 times. The stretching may be performed after the dyeing treatment, or may be performed while dyeing. Moreover, it is also possible to extend and then dye. If necessary, swelling treatment, cross-linking treatment, washing treatment, drying treatment, etc. are performed on the PVA-based film. For example, by immersing the PVA-based film in water and washing it before dyeing, not only the dirt and anti-adhesives on the surface of the PVA-based film can be removed, but also the PVA-based film can be swelled to prevent uneven dyeing.

The above-mentioned polarizer can be typically produced by using a laminate of two or more layers. Specific examples of the polarizer obtained by using the laminate include a polarizer obtained by using a laminate of a resin substrate and a PVA-based resin layer formed on the resin substrate. A polarizer obtained by using a laminate of a resin substrate and coating a PVA-based resin layer formed on the resin substrate can be produced, for example, by the following steps: apply a PVA-based resin solution to a resin substrate and make it After drying, a PVA-based resin layer is formed on the resin substrate to obtain a laminate of the resin substrate and the PVA-based resin layer; and the laminate is extended and dyed to form the PVA-based resin layer into a polarizer. In this embodiment, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is preferably formed on one side of the resin substrate. The stretching typically includes stretching by immersing the layered body in an aqueous solution of boric acid. In addition, the stretching preferably further includes a step of in-air stretching the layered body at a high temperature (eg, 95° C. or higher) before stretching in a boric acid aqueous solution. The total stretching ratio of the above-mentioned laminate is preferably 5.0 times or more, more preferably 5.5 times or more, with respect to the original length of the laminate. Hereinafter, the embodiment of the present invention in which the polarizer is obtained as described above will be referred to as Embodiment A. The details of the manufacturing method of the polarizer are described in, for example, Japanese Patent Laid-Open No. 2012-73580 (Japanese Patent No. 5414738 ) and Japanese Patent No. 6470455 . In this specification, the entirety of these publications is incorporated by reference.

In one embodiment of the present invention, the total stretching magnification of the above-mentioned laminated body is preferably 3.0 to 4.5 times the original length of the laminated body, which is obviously smaller than normal. Even at the aforementioned total extension ratio, a polarizer with acceptable optical properties can be obtained by a combination of halide addition and drying shrinkage treatment. In addition, in the embodiment of the present invention, the stretching ratio of the aerial auxiliary stretching is preferably larger than the stretching ratio of the boric acid water stretching. More specifically, the ratio of the extension magnification of the aerial auxiliary extension to the extension magnification of the underwater extension (the underwater extension/the aerial auxiliary extension) is preferably 0.4 to 0.9, more preferably 0.5 to 0.8. By making such a configuration, even if the total magnification of extension is small, a polarizer having acceptable optical characteristics can be obtained. In addition, the layered body is preferably subjected to drying shrinkage treatment in which the layered body is heated while being transported in the longitudinal direction to shrink by 2% or more in the width direction. In one embodiment, the manufacturing method of the polarizer includes sequentially performing an air-assisted stretching treatment, a dyeing treatment, an underwater stretching treatment, and a drying shrinkage treatment on the laminate. By introducing auxiliary stretching, the crystallinity of the PVA-based resin can be improved even when the PVA-based resin is coated on the thermoplastic resin, and high optical properties can be achieved. Furthermore, the orientation of the PVA-based resin is improved in advance, thereby preventing problems such as lowering or dissolving the orientation of the PVA-based resin when immersed in water in the subsequent dyeing step or stretching step, and high optical properties can be achieved. In addition, when the PVA-based resin layer is immersed in a liquid, the disorder of orientation of the polyvinyl alcohol molecules and the decrease in the orientation can be suppressed compared to the case where the PVA-based resin layer does not contain a halide. Thereby, the optical characteristic of the polarizer obtained by the process of immersing the laminated body in liquid, such as dyeing process and underwater extension process, can be improved. In addition, by shrinking the laminate in the width direction by drying shrinkage treatment, the optical properties can be improved. The obtained laminate of resin substrate/polarizer can be used as it is (that is, the resin substrate can also be used as a protective layer of the polarizer), or the resin substrate can be peeled off from the laminate of resin substrate/polarizer, and depending on the purpose Any suitable protective layer on the peeled area layer is used later. Hereinafter, the embodiment of the present invention in which the polarizer is obtained as described above will be referred to as Embodiment B.

The thickness of the above polarizer is preferably 1µm~12µm, more preferably 2µm~10µm, more preferably 3µm~8µm. By making the thickness of the polarizer very thin as described above, it is possible to contribute to the thinning of the polarizer. Also, thermal shrinkage can be made very small.

The above-mentioned polarizer should preferably exhibit absorption dichroism at any wavelength of 380 nm to 780 nm. The single transmittance of the polarizer obtained in the above Embodiment A is preferably 42.0% to 46.0%, more preferably 44.5% to 46.0%. The degree of polarization of the polarizer should preferably be above 97.0%, preferably above 99.0%, and more preferably above 99.9%. The single transmittance of the polarizer obtained in the above-mentioned Embodiment B is preferably 40.0% or more, more preferably 41.0% or more. The upper limit of the monomer transmittance may be, for example, 49.0%. In Embodiment B, the single transmittance of the polarizer is, for example, 40.0% to 45.0%. The degree of polarization of the polarizer obtained in the above-mentioned Embodiment B is preferably 99.0% or more, more preferably 99.4% or more. The upper limit of the degree of polarization may be, for example, 99.999%. In Embodiment B, the polarization degree of the polarizer is, for example, 99.0% to 99.9%.

The orientation function (f) of the PVA-based resin constituting the polarizer obtained in Embodiment B is preferably 0.30 or less, more preferably 0.25 or less, more preferably 0.20 or less, and particularly preferably 0.15 or less. The lower limit of the orientation function may be, for example, 0.05. If the orientation function is too small, the allowable single transmittance and/or polarization degree may not be obtained.

The orientation function (f) is obtained, for example, by attenuated total reflection (ATR: attenuated total reflection) measurement using a Fourier transform infrared spectrophotometer (FT-IR) with polarized light as measurement light. Specifically, germanium is used for the microcrystalline system for making the polarizer dense, the incident angle of the measurement light is set to be 45°, and the polarized infrared rays (measurement light) to be incident are made parallel to the dense germanium crystal sample. The polarized light (s-polarized light) that vibrates against the surface, and the extending direction of the polarizer is arranged to be parallel and perpendicular to the polarization direction of the measurement light, and the measurement is carried out in this state, and then the 2941 cm ^-1 of the obtained absorbance spectrum is used. The strength is calculated according to the following formula. Here, the intensity I is a value of 2941 cm ^-1 /3330 cm ^-1 with 3330 cm ^-1 as a reference peak. Also, f=1 is fully oriented and f=0 is random. Also, we believe that the peak at 2941 cm ^-1 is due to the absorption of the vibration of the PVA backbone ( _-CH2- ) in the polarizer. f=(3＜cos ² θ＞-1)/2 =(1-D)/[c(2D+1)] =-2×(1-D)/(2D+1) However, when c=( When 3cos ² β-1)/2 and the vibration of 2941cm ^-1 , β=90°. θ: The angle of the molecular chain relative to the extension direction β: The angle of the transition dipole moment relative to the molecular chain axis D=(I _⊥ )/(I _// ) (At this time, the more oriented the PVA molecule is, the larger the D is) I _⊥ : The absorption intensity when the polarization direction of the measured light is perpendicular to the extending direction of the polarizer I _// : The absorption intensity when the polarization direction of the measured light is parallel to the extending direction of the polarizer

The polarizer obtained in the above-mentioned Embodiment B is preferably such that the PVA-based resin constituting the PVA-based resin film (substantially the polarizer) includes a PVA-based resin modified with an acetylacetate group. With the above configuration, a polarizer having a desired penetration strength can be obtained. When the entire PVA-based resin is 100% by weight, the blending amount of the PVA-based resin modified with acetylacetate groups is preferably 5% by weight to 20% by weight, more preferably 8% by weight to 12% by weight.

C. Protective layer The protective layer contains an epoxy resin having an aromatic skeleton and a diol skeleton.

C-1. Epoxy resin The protective layer is preferably composed of a photocationic polymer cured product of an epoxy resin having an aromatic skeleton and a diol skeleton, or a cured product of a coating film of an organic solvent solution of the epoxy resin. The protective layer contains an epoxy resin having an aromatic skeleton and a diol skeleton, thereby obtaining a polarizing plate with excellent adhesion and curved surface compliance although it is very thin. In addition, the protective layer is preferably a photocationic polymerized cured product of an epoxy resin having an aromatic skeleton and a diol skeleton. Hereinafter, the constituent components of the protective layer will be specifically described, and then the characteristics of the protective layer will be described.

As the aromatic skeleton in the above epoxy resin, a bisphenol A type skeleton, a bisphenol F type skeleton, a biphenyl skeleton and the like can be mentioned. More specifically, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, biphenyl type epoxy resin, naphthalene ring-containing epoxy resin, epoxy resin having a bicyclic ring can be exemplified. Pentadiene skeleton epoxy resin, phenol novolac type resin, cresol novolac type epoxy resin, triphenylmethane type epoxy resin, aliphatic epoxy resin, aliphatic epoxy resin and aromatic ring Oxygen resin copolymer epoxy resin, etc., among these, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, biphenyl type epoxy resin, naphthalene ring-containing epoxy resin As the epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, epoxy resin containing naphthalene ring, and biphenyl type epoxy resin can be preferably used.

The above-mentioned diol skeleton preferably contains an aliphatic skeleton having 2 to 6 carbon atoms. More specifically, 1,4-butanediol, 1,6-hexanediol, 1,4-naphthalenediol, 1,6-naphthalenediol, etc. are mentioned; among these, 1,4 is also preferably used -Butanediol, 1,6-Hexanediol.

The glass transition temperature (Tg) of the above epoxy resin is 40°C or lower, preferably 35°C or lower. Therefore, the Tg of the protective layer is 40°C or lower, preferably 35°C or lower. The lower limit of the glass transition temperature (Tg) of the epoxy resin is preferably 0°C. When the glass transition temperature (Tg) of the epoxy resin is within the above-mentioned range, a polarizing plate having excellent adhesion and excellent conformability to curved surfaces can be obtained. On the other hand, if the glass transition temperature (Tg) of the epoxy resin is lower than 0° C., the epoxy resin may become sticky.

In the embodiment of the present invention, an epoxy resin and other resins may be used in combination. That is, a blend or copolymer of epoxy resin and other resins may also be used for forming the protective layer. Other resins include, for example, styrene-based resins, polyethylene, polypropylene, polyamide, polyphenylene sulfide, polyether ether ketone, polyester, polystyrene, polyphenylene ether, polyacetal, and polyimide , Polyetherimide and other thermoplastic resins. The type and blending amount of the resin to be used in combination can be appropriately set according to the purpose, the properties desired for the obtained film, and the like.

When the epoxy resin and other resins are used together, the content of the epoxy resin is preferably 50% by weight to 100% by weight, preferably 60% by weight to 100% by weight, and more preferably 70% by weight relative to the total of the epoxy resin and other resins. % by weight to 100% by weight, preferably 80% by weight to 100% by weight. When the content is less than 50% by weight, the heat resistance of the protective layer and the sufficient adhesion to the polarizer may not be obtained.

C-2. Hardener The epoxy resin can be hardened by using it with any suitable hardener. The hardener can be any suitable hardener that can harden the epoxy resin. In one embodiment, the hardener contains a photocationic polymerization initiator. By including a photocationic polymerization initiator, a protective layer which is a cationic polymerization cured product can be formed. As a photocationic polymerization initiator, any appropriate compound which can harden the epoxy resin which has an aromatic skeleton and a diol skeleton by light irradiation, such as an ultraviolet-ray, can be used. The photocationic polymerization initiator may be used alone or in combination of two or more.

Examples of the photocationic polymerization initiator include triphenyl perylene hexafluoroantimonate, triphenyl perylene hexafluorophosphate, p-(phenylthio)phenyldiphenyl perylene hexafluoroantimonate, p-(phenylthio) base) phenyldiphenyl perylene hexafluorophosphate, 4-chlorophenyldiphenyl perylene hexafluorophosphate, 4-chlorophenyldiphenyl perylene hexafluoroantimonate, bis[4-(diphenyl Peryl)phenyl]sulfide bis-hexafluorophosphate, bis[4-(diphenylperylanyl)phenyl]sulfide bishexafluoroantimonate, (2,4-cyclopentadien-1-yl )[(1-methylethyl)benzene]-Fe-hexafluorophosphate, diphenyliodonium hexafluoroantimonate, etc. It is preferable to use a photocationic polymerization initiator of triphenyl perionium salt type hexafluoroantimonate type, and a photocationic polymerization initiator of diphenyliodonium salt type hexafluoroantimonate type.

Commercially available ones can also be used as the photocationic polymerization initiator. Commercially available products include SP-170 (manufactured by ADEKA), CPI-101A (manufactured by SAN-APRO), WPAG-1056 (manufactured by Wako Pure Chemical Industries, Ltd.) The diphenyliodonium salt is WPI-116 (manufactured by Wako Pure Chemical Industries, Ltd.) of the hexafluoroantimonate type, and the like.

Relative to 100 parts by weight of the epoxy resin, the content of the photocationic polymerization initiator is preferably 0.1 parts by weight to 3 parts by weight, more preferably 0.25 parts by weight to 2 parts by weight. If the content of the photocationic polymerization initiator is less than 0.1 part by weight, sufficient curing may not be achieved even when irradiated with light (ultraviolet rays).

C-3. Composition and characteristics of protective layer The protective layer includes an epoxy resin having an aromatic skeleton and a diol skeleton as described above. In addition, the protective layer is preferably composed of a photocationic polymer cured product of an epoxy resin having an aromatic skeleton and a diol skeleton, or a cured product of a coating film of an organic solvent solution of the epoxy resin. In the case of the hardened or cured product, the thickness can be much thinner than that of an extruded film. The thickness of the protective layer is preferably 10µm or less, preferably 7µm or less, more preferably 5µm or less, especially 3µm or less. The thickness of the protective layer may be, for example, 1 µm or more. The epoxy resin having an aromatic skeleton and a diol skeleton has excellent adhesion between the protective layer and the polarizer as a cured product. Therefore, even with the above-mentioned thickness, the polarizer can be protected to the same extent as the protective layer using the conventional thin film.

The protective layer (hardened product of an epoxy resin having an aromatic skeleton and a diol skeleton) may contain any appropriate additives according to the purpose. Specific examples of additives include: ultraviolet absorbers; leveling agents; antioxidants such as hindered phenol-based, phosphorus-based, and sulfur-based additives; stabilizers such as light-resistant stabilizers, weather-resistant stabilizers, and thermal stabilizers; and reinforcing materials such as glass fibers and carbon fibers. ;Near-infrared absorbers; ginseng (dibromopropyl) phosphate, triallyl phosphate, antimony oxide and other flame retardants; anionic, cationic, nonionic surfactants and other antistatic agents; inorganic pigments , organic pigments, dyes and other colorants; organic fillers or inorganic fillers; resin modifiers; organic fillers or inorganic fillers; plasticizers; lubricants; antistatic agents; flame retardants, etc. Additives are usually added to the solution when the protective layer is formed. The type, quantity, combination, addition amount, etc. of the additives can be appropriately set according to the purpose.

D. Polarizing plate with retardation layer The polarizing plate described in the above item C can be provided in the form of a laminate with other optical films and/or optical members. In one embodiment, the polarizing plate can be provided in the form of a laminate with a retardation film (polarizing plate with retardation layer). Therefore, the present invention includes a polarizing plate with a retardation layer, which has the above-mentioned polarizing plate. The polarizing plate with retardation layer according to the embodiment of the present invention includes the above-described polarizing plate and retardation layer. Optical properties (eg, refractive index properties, in-plane retardation (Re), thickness direction retardation (Rth), wavelength dispersion properties), number, combination, and arrangement order of the retardation layer can be appropriately set according to the purpose.

Example Hereinafter, the present invention will be specifically described by means of embodiments, but the present invention is not limited by these embodiments. The measurement method of each characteristic is as follows. In addition, unless otherwise noted, "parts" and "%" in the examples are based on weight.

(1) Puncture test The polarizing plates or polarizers obtained in the Examples or Comparative Examples were placed in a compression tester equipped with a needle (manufactured by KATO TECH CO., LTD., product name "NDG5", needle penetration force measurement specification), and were placed in a chamber. In a warm (23℃±3℃) environment, puncture with a load of 5kg. Calculate the elongation (mm) and strength (g) of the polarizing plate or polarizer when it is about to break. (2) Thickness The thickness of the polarizing plates or polarizers obtained in Examples or Comparative Examples was measured using a dial gauge (manufactured by PEACOCK, product name "DG-205", and a dial gauge frame (product name "pds-2"). (3) Glass transition temperature Tg After the protective layer obtained in the example or the comparative example was cut into a long sheet, a viscoelastic spectrometer (manufactured by SII NanoTechnology Inc., product name "DMS6100") was used in the temperature range of -80°C to 150°C, and the temperature rise and fall rate was 2. The measurement was performed under the conditions of °C/min and a frequency of 1 Hz. (4) Adhesion Test pieces (50 mm×50 mm) were cut out from the polarizing plates obtained in Examples and Comparative Examples, and the test pieces were formed on two sides opposite to the direction perpendicular to the absorption axis direction and the absorption axis direction of the polarizer, respectively. The polarizer side surface of the test piece was coated with an adhesive and attached to the glass plate. Next, a square grid of 10×10 was drawn on the side surface of the protective layer (cured product of the coating film) with a cutter, and an adhesive tape (manufactured by Sekisui Chemical Industry Co., Ltd.) was attached to the surface. The adhesive tape was then peeled off and the number of peeled squares in the 100 square grids was assessed. Good: The number of grids is more than 50 Bad: less than 50 grids (5) Surface compliance A jig assumed to be the corner of a smartphone was made of acrylic resin, and the polarizers obtained in Examples and Comparative Examples were made to conform to the curved portion and stretched by hand to visually evaluate whether there were wrinkles or cracks in the polarizers. Good: Wrinkles, cracks, or cracks cannot be confirmed Bad: Wrinkles, cracks or cracks confirmed

<Example 1> 1. Fabrication of polarizer/resin base laminate The resin substrate is a long strip of amorphous isophthalic acid copolymer polyethylene terephthalate film (thickness: 100µm) with a water absorption rate of 0.75% and a Tg of about 75°C. Corona treatment was performed on one side of the resin substrate. A PVA-based resin obtained by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetylacetate modified PVA (manufactured by Mitsubishi Chemical Co., trade name "GOHSEFIMER Z410") at a ratio of 9:1 To 100 parts by weight, 13 parts by weight of potassium iodide was added to prepare an aqueous PVA solution (coating liquid). The above-mentioned PVA aqueous solution was coated on the corona-treated surface of the resin substrate and dried at 60° C. to form a PVA-based resin layer with a thickness of 13 μm, thereby producing a laminate. The obtained layered body was uniaxially stretched by 2.4 times the free end in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds in an oven at 130°C (aerial-assisted stretching treatment). Next, the layered body was immersed in an insolubilization bath (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40° C. for 30 seconds (insolubility treatment). Next, it was immersed for 60 seconds in a dyeing bath with a liquid temperature of 30° C. (an aqueous iodine solution obtained by mixing iodine and potassium iodide at a weight ratio of 1:7 with respect to 100 parts by weight of water) while adjusting the concentration. So that the monomer transmittance (Ts) of the polarizer finally obtained was 41.5%±0.1% (dyeing treatment). Next, it was immersed in a cross-linking bath (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds in a cross-linking bath (cross-linking treatment). ). Then, while immersing the layered body in a boric acid aqueous solution (boric acid concentration 4.0 wt %, potassium iodide 5 wt %) at a liquid temperature of 70° C., uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds to The total extension ratio was made 5.5 times (in-water extension treatment). Then, the layered body was immersed in a cleaning bath (aqueous solution obtained by mixing 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 20°C (cleaning treatment). After that, while drying in an oven maintained at 90°C, the contact surface temperature was maintained at 75°C with a heating roll made of SUS for about 2 seconds (drying shrinkage treatment). The shrinkage rate of the laminate in the width direction under the drying shrinkage treatment was 5.2%. In the above-described manner, a polarizer with a thickness of 5 µm was formed on the resin substrate to produce a polarizer/resin substrate laminate. Hereinafter, this polarizer is referred to as polarizer A.

2. Preparation of protective layer forming composition 30 parts of epoxy resins (manufactured by Mitsubishi Chemical Co., "YX7105") having an aromatic skeleton and a diol skeleton were dissolved in 67.6 parts of methyl ethyl ketone to obtain an epoxy resin solution. To the obtained epoxy resin solution, 2.4 parts of a photocationic polymerization initiator (manufactured by San-Apro Ltd., trade name: CPI (registered trademark)-100P) was added to obtain a protective layer forming composition.

3. Preparation of polarizing plate The protective layer-forming composition obtained in 2. was coated on the polarizer surface of the polarizing plate obtained above with a wire bar, and the coated film was dried at 60° C. for 3 minutes. Next, ultraviolet rays were irradiated using a high-pressure mercury lamp so that the accumulated light amount would be 600 mJ/cm ² to form a protective layer. The thickness of the protective layer is 2µm~3µm, and the glass transition temperature (Tg) is 31℃. Hereinafter, this protective layer is referred to as protective layer A. In the above-described manner, a laminate having a configuration of protective layer A/polarizer A/resin substrate was obtained. And after peeling the resin base material of this laminated body, the protective layer A was formed in the same method on the surface opposite to the protective layer of the polarizer. In the above-described manner, a polarizing plate having a configuration of protective layer A/polarizer A/protective layer A was obtained. The polarizer has an elongation of 1.44mm, a strength of 344g, and a thickness of 11µm. The obtained polarizing plate was used for the evaluation of the above-mentioned (4) and (5). The results are listed in Table 1.

<Example 2> 1. Preparation of polarizer/resin substrate laminate The thermoplastic resin substrate is a long strip of amorphous isophthalic acid copolymerized with polyethylene terephthalate having a water absorption rate of 0.75% and a Tg of about 75°C Ethylene formate film (thickness: 100µm). Corona treatment (treatment condition: 55W·min/m ² ) was performed on one side of the resin substrate. The PVA system is a 9:1 mixture of polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetylacetate modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "GOHSEFIMER Z410") To 100 parts by weight of resin, 13 parts by weight of potassium iodide was added to prepare an aqueous PVA solution (coating liquid). The above-mentioned PVA aqueous solution was coated on the corona-treated surface of the resin substrate and dried at 60° C. to form a PVA-based resin layer with a thickness of 13 μm, thereby producing a laminate. The obtained layered body was uniaxially stretched by 2.4 times the free end in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds in an oven at 130°C (aerial-assisted stretching treatment). Next, the layered body was immersed in an insolubilization bath (a boric acid aqueous solution obtained by blending 4 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 40° C. for 30 seconds (insolubility treatment). Next, it was immersed for 60 seconds in a dyeing bath with a liquid temperature of 30° C. (an aqueous iodine solution obtained by mixing iodine and potassium iodide at a weight ratio of 1:7 with respect to 100 parts by weight of water) while adjusting the concentration. So that the single transmittance (Ts) of the polarizer finally obtained was 41.6% (dyeing treatment). Next, it was immersed in a crosslinking bath (a boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 5 parts by weight of boric acid with respect to 100 parts by weight of water) for 30 seconds in a crosslinking bath (crosslinking treatment). ). Then, while immersing the layered body in a boric acid aqueous solution (boric acid concentration 4.0 wt %, potassium iodide 5.0 wt %) at a liquid temperature of 62° C., uniaxially stretched in the longitudinal direction (longitudinal direction) between rolls with different peripheral speeds to The total magnification of stretching was made 3.0 times (in-water stretching treatment: the stretching magnification in underwater stretching treatment was 1.25 times). Then, the layered body was immersed in a cleaning bath (aqueous solution obtained by mixing 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 20°C (cleaning treatment). After that, while drying in an oven maintained at 90°C, the contact surface temperature was maintained at 75°C with a heating roll made of SUS for about 2 seconds (drying shrinkage treatment). The shrinkage rate of the laminate in the width direction under the drying shrinkage treatment was 2%. A polarizer with a thickness of 6.0 µm was formed on the resin substrate in the above manner. Hereinafter, this polarizer is referred to as polarizer B. The orientation function of the resulting polarizer was 0.15. A polarizing plate having a configuration of protective layer A/polarizer B/protective layer A was obtained in the same manner as in Example 1 except that the polarizer was modulated in the above-mentioned method. The polarizer has an elongation of 1.66mm, a strength of 415g and a thickness of 12µm. The obtained polarizing plate was used for the evaluation of the above-mentioned (4) and (5). The results are listed in Table 1.

(Comparative Example 1) 1. Preparation of protective layer forming composition 15 parts of epoxy resins (Mitsubishi Chemical Co. make, trade name: jER (registered trademark) YX4000) which have a biphenyl skeleton were melt|dissolved in 83.8 parts of methyl ethyl ketones, and the epoxy resin solution was obtained. To the obtained epoxy resin solution, 1.2 parts of a photocationic polymerization initiator (manufactured by San-Apro Ltd., trade name: CPI (registered trademark)-100P) was added to obtain a protective layer forming composition. Hereinafter, the protective layer formed of this protective layer-forming composition is referred to as protective layer B. The glass transition temperature (Tg) of the protective layer B was 106°C. A polarizing plate having a configuration of protective layer B/polarizer A/protective layer B was obtained in the same manner as in Example 1, except that the protective layer forming composition was prepared in the above-mentioned manner. The polarizer has an elongation of 1.17mm, a strength of 256g, and a thickness of 11µm. The obtained polarizing plate was used for the evaluation of the above-mentioned (4) and (5). The results are listed in Table 1.

(Comparative Example 2) A polarizing plate having a configuration of protective layer B/polarizer B/protective layer B was obtained in the same manner as in Comparative Example 1, except that the polarizer B was obtained in the same manner as in Example 2. The polarizer has an elongation of 1.26mm, a strength of 337g, and a thickness of 12µm. The obtained polarizing plate was used for the evaluation of the above-mentioned (4) and (5). The results are listed in Table 1.

(Comparative Example 3) A polarizing plate having a configuration of protective layer A/polarizer A was obtained in the same manner as in Example 1, except that the protective layer A was only provided on one side of the polarizer A. The elongation of the polarizing plate was 1.35 mm after the puncture test from the protective layer side, and 1.00 mm or less after the puncture test from the polarizer side. The strength of the polarizing plate was 285 g after the puncture test from the protective layer side, and 100 g or less after the puncture test from the polarizer side. And, the thickness of the polarizing plate is 8µm. The obtained polarizing plate was used for the evaluation of the above-mentioned (4) and (5). The results are listed in Table 1.

(Comparative Example 4) The polarizer A was fabricated according to the same method as in Example 1, and no protective layer was provided. The polarizer has an elongation of 1.00mm or less, a strength of 100g or less, and a thickness of 5µm. The resulting polarizer was used for the evaluations of (4) and (5) above. The results are listed in Table 1.

(Comparative Example 5) The polarizer B was fabricated according to the same method as in Example 2, and no protective layer was provided. The polarizer has an elongation of 1.38mm, a strength of 267g, and a thickness of 6µm. The resulting polarizer was used for the evaluations of (4) and (5) above. The results are listed in Table 1.

(Comparative Example 6) Except using an acrylic film (thickness 20µm, glass transition temperature (Tg) 123°C, hereinafter referred to as protective layer C) for the protective layer, a protective layer C/polarizer A/protective layer C was obtained in the same manner as in Example 1 The polarizing plate composed of it. The polarizing plate has an elongation of 1.00mm or less, a strength of 500g or more, and a thickness of 45µm. The obtained polarizing plate was used for the evaluation of the above-mentioned (4) and (5). The results are listed in Table 1.

(Comparative Example 7) A polarizing plate having a configuration of protective layer C/polarizer A was obtained in the same manner as in Comparative Example 6, except that the protective layer C was formed only on one side of the polarizer A. The polarizing plate has an elongation of 1.00mm or less, a strength of 500g or more, and a thickness of 25µm. The obtained polarizing plate was used for the evaluation of the above-mentioned (4) and (5). The results are listed in Table 1.

比較例3之(1)係表示從保護層側進行穿刺試驗後之結果，(2)係表示從偏光件側進行穿刺試驗後之結果。 [Table 1]

(1) of Comparative Example 3 shows the result of the puncture test from the protective layer side, and (2) shows the result of the puncture test from the polarizer side.

＜Assessment＞ As apparent from Table 1, the polarizing plates having the constitutions of Examples 1 and 2 were excellent in adhesion and excellent in conformability to curved surfaces.

industrial availability The polarizing plate of the present invention can be suitably used in an image display device. Examples of image display devices include portable devices such as portable information terminals (PDAs), smart phones, mobile phones, clocks, digital cameras, and portable game consoles; OA devices such as computer monitors, notebook computers, and copiers; Video cameras, televisions, microwave ovens and other household electrical appliances; rear light monitors, monitors for car navigation systems, car audio and other in-vehicle devices; digital signage, display devices such as information guide screens for commercial stores; monitoring monitors such as alarm machines; nursing care monitors, medical monitors, and other nursing care medical devices.

10: Polarizer 20: Protective layer 30: Protective layer 100: polarizer

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

10: Polarizer

20: Protective layer

30: Protective layer

100: polarizer

Claims (7)

A polarizer, comprising a polarizer and a protective layer disposed on both sides of the polarizer; The protective layer comprises an epoxy resin with an aromatic skeleton and a diol skeleton, and its glass transition temperature is below 40°C; The elongation of the polarizing plate in the puncture test is 1.40 mm or more. The polarizing plate of claim 1, wherein the polarizer is composed of a polyvinyl alcohol-based resin film containing a dichroic substance, and the orientation function is 0.30 or less. The polarizing plate according to claim 1 or 2, wherein the protective layer is composed of a cured product of photocationic polymerization of the epoxy resin, or a cured product of a coating film of an organic solvent solution of the epoxy resin. The polarizing plate according to any one of claims 1 to 3, whose total thickness is 20 μm or less. The polarizing plate according to any one of claims 1 to 4, whose puncture strength is 300 g or more. The polarizing plate according to any one of claims 1 to 5, wherein the glass transition temperature of the protective layer is 0°C or higher. A polarizing plate with a retardation layer, comprising a retardation layer, a polarizer and a protective layer according to any one of claims 1 to 6.

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