JP2009244860A - Polarizing plate, optical member, and liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing plate which is made thin and light and has an improved hardness of a protective layer while keeping an excellent adhesion between a polarizing film and the protective layer, to provide an optical member using the polarizing plate, and to provide a liquid crystal display. <P>SOLUTION: The polarizing plate has a protective layer formed on at least one side of the polarizing film composed of a polyvinyl alcohol resin. The protective layer is composed of a cured product of an active energy ray-curable resin compound which contains an active energy ray-curable compound and fine particles. The polarizing plate has the protective layer having an elastic modulus of 4000-10,000 MPa. Silica particles are suitably used as the fine particles. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a polarizing plate having a protective layer on one side or both sides of a polarizing film made of a polyvinyl alcohol-based resin. The present invention also relates to an optical member and a liquid crystal display device using the polarizing plate.

  The polarizing plate is useful as an optical component constituting a liquid crystal display device. Conventionally, the polarizing plate has a configuration in which a protective layer made of a transparent resin film is laminated on one or both sides of a polarizing film using an aqueous adhesive or the like. As such a transparent resin film, a triacetyl cellulose film (TAC film) is often used because of its excellent optical transparency and moisture permeability. The polarizing plate is bonded to the liquid crystal cell with an adhesive via another optical function layer as necessary, and is incorporated into the liquid crystal display device.

  In recent years, with the development of liquid crystal display devices in mobile devices such as notebook personal computers, mobile phones, car navigation systems, etc., the polarizing plates that make up liquid crystal display devices are thinner and lighter and have higher durability (high mechanical strength). Is now required. In addition, liquid crystal display devices for mobile use are required to be usable under wet heat, and polarizing plates used therefor are also required to have high heat and humidity resistance. In particular, when exposed to a high temperature and high humidity for a long period of time, there was a problem that the polarizing performance deteriorated or the polarizing film contracted. Therefore, the protective layer laminated on the polarizing film is required to improve the mechanical strength and the ability to suppress the contraction of the polarizing film (shrinkage suppressing force) as well as reducing the thickness and weight. .

  However, in the polarizing plate bonded with a TAC film as a protective layer, it is difficult to make the thickness of the protective layer 20 μm or less from the viewpoints of handleability and durability at the time of work, and there is a limit to reducing the thickness and weight. .

  As a technique that can solve the above problem, for example, Patent Document 1 discloses a technique in which a transparent thin film layer is formed by applying a resin solution to one or both sides of a polarizing film made of a hydrophilic polymer. Patent Document 2 discloses that a protective film is formed on a polarizing film by curing an energy ray-curable composition containing an energy ray-polymerizable compound having a dicyclopentanyl residue or a dicyclopentenyl residue. A forming technique is disclosed. Patent Document 3 discloses a polarizing plate having a protective film mainly composed of an epoxy resin on at least one surface of a polarizing film. Patent Document 4 discloses that at least one surface of a polarizing film is protected with a cured product of an active energy ray-curable resin composition.

JP 2000-199819 A JP 2003-185842 A JP 2004-245924 A JP 2005-92112 A

  An object of the present invention is to provide a polarizing plate in which thin and light weight and the hardness of the protective layer are improved while maintaining good adhesion between the polarizing film and the protective layer. Another object of the present invention is to provide an optical member and a liquid crystal display device using such a polarizing plate.

  The present invention is a polarizing plate having a protective layer on at least one surface of a polarizing film made of a polyvinyl alcohol-based resin, the protective layer comprising an active energy ray-curable resin composition containing an active energy ray-curable compound and fine particles. Provided is a polarizing plate comprising a cured product of the product and having an elastic modulus of 4000 to 10,000 MPa.

  The active energy ray-curable compound preferably includes an epoxy compound having one or more epoxy groups bonded to an alicyclic ring. It is more preferable that the active energy ray-curable compound further includes an oxetane compound.

  The active energy ray-curable compound may include a (meth) acrylic compound having one or more (meth) acryloyloxy groups in the molecule. The (meth) acrylic compound having one or more (meth) acryloyloxy groups in the molecule has a cured product obtained by curing only the (meth) acrylic compound in the presence of a polymerization initiator and having 3000 MPa or more. A (meth) acrylic compound giving an elastic modulus is preferable.

  The active energy ray-curable resin composition preferably contains 5 to 250 parts by weight of the fine particles with respect to 100 parts by weight of the active energy ray-curable compound.

  The fine particles are preferably silica particles having a particle size of 100 nm or less. Moreover, you may use the silica particle which has 1 or more types of functional groups selected from the group which consists of a hydroxyl group, an epoxy group, a (meth) acryloyloxy group, and a vinyl group on the surface.

  The present invention also provides an optical member comprising a laminate of the polarizing plate of the present invention and an optical functional layer, and a liquid crystal display device in which the polarizing plate or optical member of the present invention is disposed on one or both sides of a liquid crystal cell. .

  According to the present invention, since the thickness of the protective layer can be reduced as compared with a conventional TAC film or the like, the polarizing plate can be reduced in thickness and weight, and the adhesion between the polarizing film and the protective layer is also good. It is. Furthermore, since the hardness of the protective layer is improved, the mechanical strength of the polarizing plate can be improved, and even when the thickness of the protective layer is reduced compared to the conventional case, The shrinkage of the polarizing film can be effectively suppressed. Such a polarizing plate of the present invention and an optical member using the same can be suitably applied to, for example, a liquid crystal display device for mobile use.

<Polarizing plate>
The polarizing plate of the present invention has a protective layer made of a cured product of an active energy ray-curable resin composition containing an active energy ray-curable compound and fine particles on one or both sides of a polarizing film made of a polyvinyl alcohol resin. Can be obtained. Hereinafter, the polarizing plate of the present invention will be described in detail.

(Polarizing film)
The polarizing film used in the present invention is made of a polyvinyl alcohol resin, and specifically, a dichroic dye is adsorbed and oriented on a uniaxially stretched polyvinyl alcohol resin film.

  The polyvinyl alcohol resin constituting the polarizing film can be obtained by saponifying a polyvinyl acetate resin. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, vinyl ethers, and the like. The saponification degree of the polyvinyl alcohol-based resin is usually about 85 to 100 mol%, preferably 98 to 100 mol%. The polyvinyl alcohol-based resin may be further modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The degree of polymerization of the polyvinyl alcohol resin is usually about 1,000 to 10,000, preferably about 1,500 to 10,000.

  A film obtained by forming such a polyvinyl alcohol resin is used as a raw film of a polarizing film. The method for forming a polyvinyl alcohol-based resin is not particularly limited, and can be formed by a known method. Although the film thickness of a polyvinyl alcohol-type raw film is not specifically limited, For example, it is about 10 micrometers-150 micrometers.

  A polarizing film is usually a process of uniaxially stretching a raw film made of a polyvinyl alcohol resin as described above, a process of dyeing a polyvinyl alcohol resin film with a dichroic dye and adsorbing the dichroic dye, two colors It is manufactured through a step of treating a polyvinyl alcohol-based resin film adsorbed with a functional dye with an aqueous boric acid solution and a step of washing with water after the treatment with an aqueous boric acid solution.

  Uniaxial stretching may be performed before dyeing with the dichroic dye, may be performed simultaneously with the dyeing, or may be performed after the dyeing. When uniaxial stretching is performed after dyeing with a dichroic dye, the uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Moreover, it is also possible to perform uniaxial stretching in these several steps. In uniaxial stretching, it may be uniaxially stretched between rolls having different peripheral speeds, or may be uniaxially stretched using a hot roll. Further, it may be dry stretching such as stretching in the air, or may be wet stretching in which stretching is performed in a state swollen with a solvent. The draw ratio is usually about 4 to 8 times.

  In order to dye the polyvinyl alcohol resin film with the dichroic dye, for example, the polyvinyl alcohol resin film may be immersed in an aqueous solution containing the dichroic dye. As the dichroic dye, iodine, a dichroic dye or the like is used. In addition, it is preferable that the polyvinyl alcohol-type resin film performs the immersion process to water before a dyeing process.

  When iodine is used as the dichroic dye, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide is usually employed as a dyeing method. The content of iodine in this aqueous solution is usually about 0.01 to 0.5 parts by weight with respect to 100 parts by weight of water, and the content of potassium iodide is usually 0.00 with respect to 100 parts by weight of water. About 5 to 10 parts by weight. The temperature of the aqueous solution used for dyeing is usually about 20 to 40 ° C., and the immersion time (dyeing time) in this aqueous solution is usually about 30 to 300 seconds.

On the other hand, when a dichroic dye is used as the dichroic dye, a method of immersing a polyvinyl alcohol-based resin film in a dye aqueous solution containing a water-soluble dichroic dye is usually employed as a dyeing method. The content of the dichroic dye in this dye aqueous solution is usually about 1 × 10 ⁻³ to 1 × 10 ⁻² parts by weight with respect to 100 parts by weight of water. The dye aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing assistant. The temperature of the aqueous dye solution is usually about 20 to 80 ° C., and the immersion time (dyeing time) in the aqueous dye solution is usually about 30 to 300 seconds.

  The boric acid treatment after dyeing with a dichroic dye is performed by immersing the dyed polyvinyl alcohol-based resin film in a boric acid-containing aqueous solution. The boric acid content in the boric acid-containing aqueous solution is usually about 2 to 15 parts by weight, preferably about 5 to 12 parts by weight with respect to 100 parts by weight of water. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide. The content of potassium iodide in the boric acid-containing aqueous solution is usually about 2 to 20 parts by weight, preferably about 5 to 15 parts by weight with respect to 100 parts by weight of water. The immersion time in the boric acid-containing aqueous solution is usually about 100 to 1,200 seconds, preferably about 150 to 600 seconds, and more preferably about 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 ° C or higher, preferably 50 to 85 ° C.

  The polyvinyl alcohol resin film after the boric acid treatment is usually washed with water. The water washing treatment is performed, for example, by immersing a boric acid-treated polyvinyl alcohol resin film in water. The temperature of water in the water washing treatment is usually about 5 to 40 ° C., and the immersion time is about 2 to 120 seconds. After washing with water, a drying process is performed to obtain a polarizing film. The drying treatment can be performed using a hot air dryer or a far infrared heater. A drying temperature is about 40-100 degreeC normally. The time for the drying treatment is usually about 120 to 600 seconds.

  As described above, a polarizing film in which a dichroic dye is adsorbed and oriented on a uniaxially stretched polyvinyl alcohol resin film can be produced. The thickness of the polarizing film can be about 5 to 40 μm.

(Protective layer)
In this invention, it is set as a polarizing plate by laminating | stacking the protective layer which consists of hardened | cured material of the active energy ray-curable resin composition containing an active energy ray-curable compound and microparticles | fine-particles on the single side | surface or both surfaces of the said polarizing film.

  Here, the elastic modulus of the protective layer is 4000 to 10000 MPa, preferably 4500 to 6500 MPa. When the elastic modulus of the protective layer is less than 4000 MPa, the ability to suppress the shrinkage of the polarizing film under high temperature and high humidity is lowered, and as a result, the polarization characteristics are lowered. Moreover, since the adhesiveness of a polarizing film and a protective layer worsens when the elasticity modulus of a protective layer exceeds 10,000 Mpa, problems, such as peeling of a protective layer, may arise.

  The elastic modulus of the protective layer is measured as follows. First, an active energy ray-curable resin composition for forming a protective layer is applied onto a polyethylene terephthalate film (PET film), and light irradiation is performed to cure the resin composition. Next, this cured product layer is cut into a 1 cm width × 8 cm length together with the PET film, and the PET film is peeled off to obtain a sample. Next, the upper and lower grips of the AUTOGRAPH AG-1S tester manufactured by Shimadzu Corporation were used to sandwich the both ends of the sample in the long side direction so that the distance between the grips was 5 cm, and the sample was pulled at a pulling speed of 10 mm / min. The elastic modulus is calculated from the slope of the initial straight line in the obtained stress-strain curve.

  As the active energy ray-curable compound contained in the active energy ray-curable resin composition for forming the protective layer, the elastic modulus of the protective layer obtained by curing falls within the above range, and the polarizing film, the protective layer, As long as sufficient adhesiveness is obtained, it is not particularly limited, and examples thereof include a cationic curable compound and a radical curable compound.

  An example of the cationic curable compound is an epoxy compound. Especially, since the adhesiveness of a polarizing film and a protective layer can be improved more effectively, an active energy ray hardening compound is an epoxy type which has at least 1 or more epoxy group couple | bonded with the alicyclic ring. It is preferable to include a compound (hereinafter referred to as an alicyclic epoxy compound). Here, in the present invention, the “epoxy compound” means a compound that has two or more epoxy groups in the molecule and can be cured by irradiation with active energy rays. By using an epoxy compound, the adhesion between the protective layer and the polarizing film can be further improved.

  Moreover, the epoxy group couple | bonded with the alicyclic ring has a structure shown by following formula (1). In formula, m is an integer of 2-5.

Therefore, the alicyclic epoxy compound is a compound having one or more structures represented by the above formula (1) and having a total of two or more epoxy groups in the molecule. More specifically, a compound in which one or more hydrogen groups in (CH ₂ ) _m in the above formula (1) are bonded to another chemical structure becomes an alicyclic epoxy compound. obtain. One or more hydrogen atoms in (CH ₂ ) _m may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group. Among alicyclic epoxy compounds, an epoxy compound having an oxabicyclohexane ring (m = 3 in the above formula (1)) or an oxabicycloheptane ring (m = 4 in the above formula (1)). The compound is more preferably used because of its high elastic modulus and excellent adhesion to a polarizing film. In the alicyclic epoxy compound, it is sufficient that at least one epoxy group bonded to the alicyclic ring is present, and the remaining epoxy groups may not be bonded to the alicyclic ring. Those in which both groups are bonded to the alicyclic ring are preferred. Although the structure of the alicyclic epoxy compound preferably used in the present invention is specifically exemplified below, it is not limited to these compounds.

  (A) Epoxycyclohexylmethyl epoxycyclohexanecarboxylates represented by the following formula (2):

(In the formula, R ₁ and R ₂ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)
(B) Epoxycyclohexanecarboxylates of alkanediol represented by the following formula (3):

(In the formula, R ₃ and R ₄ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and n represents an integer of 2 to 20).
(C) Epoxycyclohexyl methyl esters of dicarboxylic acid represented by the following formula (4):

(In the formula, R ₅ and R ₆ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and p represents an integer of 2 to 20).
(D) Epoxycyclohexyl methyl ethers of polyethylene glycol represented by the following formula (5):

(In the formula, R ₇ and R ₈ independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and q represents an integer of 2 to 10).
(E) Epoxycyclohexyl methyl ethers of alkanediols represented by the following formula (6):

(In the formula, R ₉ and R ₁₀ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and r represents an integer of 0 to 18).
(F) Diepoxy trispiro compound represented by the following formula (7):

(In the formula, R ₁₁ and R ₁₂ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)
(G) Diepoxy monospiro compound represented by the following formula (8):

(In the formula, R ₁₃ and R ₁₄ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)
(H) Vinylcyclohexene diepoxides represented by the following formula (9):

(In the formula, R ₁₅ represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)
(I) Epoxycyclopentyl ethers represented by the following formula (10):

(In the formula, R ₁₆ and R ₁₇ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)
(J) Diepoxytricyclodecanes represented by the following formula (11):

(In the formula, R ₁₈ represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)
Among the alicyclic epoxy compounds exemplified above, the following alicyclic epoxy compounds are commercially available or similar, and are preferably used because they are relatively easy to obtain. It is done.

(A) Esterified product of 7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and (7-oxa-bicyclo [4.1.0] hept-3-yl) methanol [formula (2 ) In which R ₁ = R ₂ = H],
(B) 4-methyl-7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and (4-methyl-7-oxa-bicyclo [4.1.0] hept-3-yl) methanol Esterified product [compound of the above formula (2), R ₁ = 4-CH ₃ , R ₂ = 4-CH ₃ ],
(C) 7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and 1,2-ethanediol esterified product [in the above formula (3), R ₃ = R ₄ = H, n = 2 Compound of
(D) (7-oxabicyclo [4.1.0] hept-3-yl) esterified product of methanol and adipic acid [in the above formula (4), R ₅ = R ₆ = H, p = 4 compound ],
(E) (4-Methyl-7-oxabicyclo [4.1.0] hept-3-yl) esterified product of methanol and adipic acid [in the above formula (4), R ₅ = 4-CH ₃ , R ₆ = 4-CH ₃ , p = 4 compound]
(F) etherified product of (7-oxabicyclo [4.1.0] hept-3-yl) methanol and 1,2-ethanediol [in the above formula (6), R ₉ = R ₁₀ = H, r = 0 compound].

  In the present invention, the above-described alicyclic epoxy compound is preferably used as the epoxy compound, but another epoxy compound may be used in combination with the alicyclic epoxy compound. Examples of other epoxy compounds include hydrogenated epoxy compounds and aliphatic epoxy compounds.

  The hydrogenated epoxy compound can be obtained by selectively hydrogenating an aromatic epoxy compound in the presence of a catalyst under pressure. Examples of aromatic epoxy compounds include bisphenol-type epoxy resins such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S; phenol novolac epoxy resins, cresol novolac epoxy resins, hydroxy Examples include novolak-type epoxy resins such as benzaldehyde phenol novolac epoxy resins; glycidyl ethers of tetrahydroxyphenylmethane, glycidyl ethers of tetrahydroxybenzophenone, and polyfunctional epoxy resins such as epoxidized polyvinylphenol. Of these, hydrogenated bisphenol A glycidyl ether is preferably used as the hydrogenated epoxy compound.

  Moreover, as an aliphatic epoxy-type compound, polyglycidyl ether of an aliphatic polyhydric alcohol or its alkylene oxide addition product can be mentioned. More specifically, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, propylene Polyethers of polyether polyols obtained by adding one or more alkylene oxides (ethylene oxide or propylene oxide) to aliphatic polyhydric alcohols such as glycol diglycidyl ether, ethylene glycol, propylene glycol and glycerin Examples thereof include glycidyl ether.

  In the present invention, the epoxy compound may be used alone or in combination of two or more, but preferably contains at least an alicyclic epoxy compound.

  In the present invention, from the viewpoint of weather resistance, refractive index, cationic polymerizability, etc., it is preferable to mainly use an epoxy compound that does not contain an aromatic ring in the molecule as the epoxy compound. Moreover, the epoxy equivalent of an epoxy compound is 30-3,000 g / equivalent normally, Preferably it is 50-1,500 g / equivalent. If the epoxy equivalent is less than 30 g / equivalent, the flexibility of the protective layer after curing may be reduced, or the adhesion with the polarizing film may be reduced. On the other hand, if it exceeds 3,000 g / equivalent, the compatibility with other components may decrease.

  When the active energy ray-curable resin composition used in the present invention contains a cationic curable compound (for example, an alicyclic epoxy compound), the content is 30 to 70 in the active energy ray curable compound. It is preferable that it is weight%, and it is more preferable that it is 40-60 weight%. When the content of the cationic curable compound is less than 30% by weight, the adhesion with the polarizing film tends to be lowered. On the other hand, when the content exceeds 70% by weight, the optical performance is improved due to yellowing of the cured film. There is a tendency to decrease.

  Moreover, when other epoxy-type compounds other than an alicyclic epoxy-type compound are used, it is preferable that the addition amount of the said other epoxy-type compound is 30 weight part or less in 100 weight part of epoxy-type compounds. When it exceeds 30 parts by weight, the elastic modulus of the cured product is lowered, and the effect of suppressing the shrinkage of the polarizing film tends to be lowered.

  When the active energy ray-curable resin composition used in the present invention contains a cationic curable compound such as an epoxy compound, a photocationic polymerization initiator is blended in the active energy ray-curable resin composition. It is preferable. When a cationic photopolymerization initiator is used, it becomes possible to form a protective layer at room temperature, so the need to consider the heat resistance of the polarizing film or distortion due to expansion is reduced, and the protective layer is placed on the polarizing film with good adhesion. Can be formed. In addition, since the photocationic polymerization initiator acts catalytically by light, it is excellent in storage stability and workability even when mixed with an epoxy compound.

  The cationic photopolymerization initiator generates a cationic species or a Lewis acid upon irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, and initiates an epoxy group polymerization reaction. In the present invention, any type of cationic photopolymerization initiator may be used, but it is preferable from the viewpoint of workability that latency is imparted. Although it does not specifically limit as a photocationic polymerization initiator, For example, aromatic diazonium salt, aromatic iodonium salt, onium salts, such as an aromatic sulfonium salt, an iron- allene complex etc. can be mentioned.

  Examples of the aromatic diazonium salt include benzenediazonium hexafluoroantimonate, benzenediazonium hexafluorophosphate, and benzenediazonium hexafluoroborate. Examples of the aromatic iodonium salt include diphenyliodonium tetrakis (pentafluorophenyl) borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, di (4-nonylphenyl) iodonium hexafluorophosphate, and the like.

  Examples of aromatic sulfonium salts include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, 4,4′-bis [diphenylsulfonio] diphenyl sulfide bishexa. Fluorophosphate, 4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide, bishexafluoroantimonate, 4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide, bis Hexafluorophosphate, 7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate, 7- [di (p-tolui) ) Sulfonio] -2-isopropylthioxanthone tetrakis (pentafluorophenyl) borate, 4-phenylcarbonyl-4′-diphenylsulfonio-diphenyl sulfide hexafluorophosphate, 4- (p-tert-butylphenylcarbonyl) -4′-diphenyl Sulfonio-diphenyl sulfide hexafluoroantimonate, 4- (p-tert-butylphenylcarbonyl) -4′-di (p-toluyl) sulfonio-diphenyl sulfide, tetrakis (pentafluorophenyl) borate and the like.

  Examples of the iron-allene complex include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, xylene-cyclopentadienyl iron (II). -Tris (trifluoromethylsulfonyl) methanide and the like.

  These photocationic polymerization initiators can be easily obtained as commercial products. For example, “Kayarad PCI-220” and “Kayarad PCI-620” (Nippon Kayaku Co., Ltd. )), “UVI-6990” (manufactured by Union Carbide), “Adekaoptomer SP-150”, “Adekaoptomer SP-170” (manufactured by ADEKA, Inc.), “CI-5102”, “ "CIT-1370", "CIT-1682", "CIP-1866S", "CIP-2048S", "CIP-2064S" (Nippon Soda Co., Ltd.), "DPI-101", "DPI-102" , “DPI-103”, “DPI-105”, “MPI-103”, “MPI-105”, “BBI-101”, “BBI-102”, “BBI” 103 "," BBI-105 "," TPS-101 "," TPS-102 "," TPS-103 "," TPS-105 "," MDS-103 "," MDS-105 "," DTS-102 " , “DTS-103” (manufactured by Midori Chemical Co., Ltd.), “PI-2074” (manufactured by Rhodia), and the like.

  These cationic photopolymerization initiators may be used alone or in combination of two or more. Among these, aromatic sulfonium salts, in particular, have ultraviolet absorption characteristics even in a wavelength region of 300 nm or more, and thus give a cured product having excellent curability and good mechanical strength and good adhesion to a polarizing film. Therefore, it is preferably used.

  The compounding quantity of a photocationic polymerization initiator is 0.5-20 weight part normally with respect to 100 weight part of cationic curable compounds, Preferably it is 1-6 weight part. When the blending amount of the cationic photopolymerization initiator is less than 0.5 parts by weight with respect to 100 parts by weight of the cationic curable compound, curing becomes insufficient, and mechanical strength and adhesion between the protective layer and the polarizing film are reduced. Tend to decrease. Moreover, when the compounding quantity of a photocationic polymerization initiator exceeds 20 weight part with respect to 100 weight part of cationic curable compounds, the hygroscopic property of hardened | cured material is high because the ionic substance in hardened | cured material increases. Thus, the durability performance may be reduced.

  When an epoxy compound is used as the cationic curable compound, an oxetane compound may be added to the active energy ray curable resin composition. By adding an oxetane compound, the viscosity of the active energy ray-curable resin composition can be lowered and the curing rate can be increased. Moreover, yellowing of a cured film can be prevented and optical performance can be improved.

  An oxetane compound is a compound having a 4-membered ring ether in the molecule, such as 3-ethyl-3-hydroxymethyloxetane, 1,4-bis [(3-ethyl-3-oxetanyl) methoxymethyl] benzene, Examples include 3-ethyl-3- (phenoxymethyl) oxetane, di [(3-ethyl-3-oxetanyl) methyl] ether, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, and phenol novolac oxetane. . These oxetane compounds can be easily obtained as commercial products. For example, all of these oxetane compounds are trade names such as “Aron Oxetane OXT-101”, “Aron Oxetane OXT-121”, “Aron Oxetane OXT-211”. , “Aron Oxetane OXT-221”, “Aron Oxetane OXT-212” (manufactured by Toagosei Co., Ltd.), and the like.

  Although the compounding quantity of an oxetane type compound is not specifically limited, Usually, it is 5 to 30 weight% in an active energy ray hardening compound, Preferably it is 10 to 25 weight%.

  Next, the radical curable compound will be described. As the radical curable compound, it is preferable to use a (meth) acrylic compound having one or more (meth) acryloyloxy groups in the molecule. By using a (meth) acrylic compound, the mechanical strength of the protective layer can be improved. Especially, it is more preferable to use the (meth) acrylic-type compound from which the elastic modulus of the hardened | cured material obtained by hardening will be 3000 Mpa or more. The elastic modulus of a cured product obtained by curing the (meth) acrylic compound alone is more preferably 3100 MPa or more. By using a (meth) acrylic compound in which the cured product obtained by curing has a modulus of elasticity of 3000 MPa or more, a protective layer having a modulus of elasticity within the above range can be obtained relatively easily. In addition, it is possible to obtain a protective layer having high mechanical strength and capable of effectively suppressing the shrinkage of the polarizing film. The “(meth) acryloyloxy group” means an acryloyloxy group or a methacryloyloxy group. The “(meth) acrylic compound” means an acrylate derivative or a methacrylic acid ester derivative, respectively. The elastic modulus of the cured product obtained by curing the (meth) acrylic compound is a resin composition comprising the (meth) acrylic compound and a radical polymerization initiator (not including other active energy ray-curable compounds). It is measured in the same manner as in the case of the protective layer except that it is used.

  The radical curable compound can be polymerized and cured by irradiating active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays in the presence of a radical photopolymerization initiator.

  Examples of the (meth) acrylic compound having one or more (meth) acryloyloxy groups in the molecule include (meth) acrylate monomers having one or more (meth) acryloyloxy groups in the molecule (hereinafter referred to as (meth) And (meth) acryloyloxy group-containing compounds such as (meth) acrylate oligomers (hereinafter referred to as (meth) acrylate oligomers) having two or more (meth) acryloyloxy groups in the molecule. Can do. These may be used alone or in combination of two or more. The “(meth) acrylate monomer” means an acrylate monomer or a methacrylate monomer, and the “(meth) acrylate oligomer” means an acrylate oligomer or a methacrylate oligomer.

  Examples of the (meth) acrylate monomer include a (meth) acrylate monomer having one (meth) acryloyloxy group in the molecule (hereinafter referred to as a monofunctional (meth) acrylate monomer), and two (meth) acrylate monomers in the molecule. ) (Meth) acrylate monomer having acryloyloxy group (hereinafter referred to as bifunctional (meth) acrylate monomer) and (meth) acrylate monomer having three or more (meth) acryloyloxy groups in the molecule (hereinafter referred to as polyfunctional) (Meth) acrylate monomer.). Only one type of (meth) acrylate monomer may be used, or two or more types may be used in combination.

  Specific examples of monofunctional (meth) acrylate monomers include tetrahydrofurfuryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxy- 3-phenoxypropyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentenyl (meth) acrylate, benzyl (meth) acrylate , Isobornyl (meth) acrylate, phenoxyethyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, ethyl cal Tall (meth) acrylate, trimethylolpropane mono (meth) acrylate, pentaerythritol mono (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate and the like.

  Moreover, a carboxyl group-containing (meth) acrylate monomer may be used as the monofunctional (meth) acrylate monomer. Examples of the carboxyl group-containing monofunctional (meth) acrylate monomer include 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, carboxyethyl (meth) acrylate, and 2- (meth). Examples include acryloyloxyethyl succinic acid, N- (meth) acryloyloxy-N ′, N′-dicarboxy-p-phenylenediamine, 4- (meth) acryloyloxyethyl trimellitic acid, and the like. Moreover, as a monofunctional (meth) acrylate monomer, a (meth) acryloylamino group-containing monomer such as 4- (meth) acryloylamino-1-carboxymethylpiperidine can be used.

  Examples of the bifunctional (meth) acrylate monomer include alkylene glycol di (meth) acrylates, polyoxyalkylene glycol di (meth) acrylates, halogen-substituted alkylene glycol di (meth) acrylates, and aliphatic polyol di (meth). Di (meth) acrylates of acrylates, hydrogenated dicyclopentadiene or tricyclodecane dialkanol, di (meth) acrylates of dioxane glycol or dioxane dialkanol, di (meth) alkylene oxide adducts of bisphenol A or bisphenol F ) Acrylates, epoxy di (meth) acrylates of bisphenol A or bisphenol F, and the like are representative, but are not limited to these, and various types can be used.

  More specific examples of the bifunctional (meth) acrylate monomer include ethylene glycol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1 , 6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, pentaerythritol di (meth) acrylate, ditri Methylolpropane di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polyethylene Glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, silicon di (meth) acrylate, hydroxypivalate ester neopentyl glycol di (meth) acrylate, 2,2-bis [4- (Meth) acryloyloxyethoxyethoxyphenyl] propane, 2,2-bis [4- (meth) acryloyloxyethoxyethoxycyclohexyl] propane, hydrogenated dicyclopentadienyl di (meth) acrylate, tricyclodecandi Methanol di (meth) acrylate, 1,3-dioxane-2,5-diyl di (meth) acrylate [also known as dioxane glycol di (meth) acrylate], hydroxypivalaldehyde and trimethylol group Di (meth) acrylate of acetal compound [chemical name: 2- (2-hydroxy-1,1-dimethylethyl) -5-ethyl-5-hydroxymethyl-1,3-dioxane] with bread, 1,3, And di (meth) acrylate of 5-tris (2-hydroxyethyl) isocyanurate.

  Examples of the polyfunctional (meth) acrylate monomer include glycerin tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol tri (meth). ) Acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, etc. ) Acrylate is typical, and in addition, poly (meth) acrylates of tri- or higher functional halogen-substituted polyols, glycerin alkylene oxide adducts Li (meth) acrylate, trimethylolpropane alkylene oxide adduct tri (meth) acrylate, 1,1,1-tris [(meth) acryloyloxyethoxyethoxy] propane, 1,3,5-tris (2-hydroxy Ethyl) isocyanurate tri (meth) acrylate, silicone hexa (meth) acrylate and the like.

  As the (meth) acrylate oligomer, a bifunctional or higher urethane (meth) acrylate oligomer (hereinafter referred to as a polyfunctional urethane (meth) acrylate oligomer), a bifunctional or higher polyester (meth) acrylate oligomer (hereinafter referred to as a polyfunctional polyester). (Meth) acrylate oligomer.) Bifunctional or higher functional epoxy (meth) acrylate oligomer (hereinafter referred to as polyfunctional epoxy (meth) acrylate oligomer). Only one type of (meth) acrylate oligomer may be used, or two or more types may be used in combination.

  Examples of the polyfunctional urethane (meth) acrylate oligomer include a urethanation reaction product of a (meth) acrylate monomer having at least one (meth) acryloyloxy group and a hydroxyl group in the molecule and a polyisocyanate, and a polyisocyanate. And urethanation reaction products of an isocyanate compound obtained by reaction with (meth) acrylate monomer having at least one (meth) acryloyloxy group and one or more hydroxyl groups in the molecule.

  Examples of the (meth) acrylate monomer having one or more (meth) acryloyloxy groups and hydroxyl groups in the molecule used for the urethanization reaction include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, glycerin di (meth) acrylate, trimethylolpropane di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (Meth) acrylate etc. are mentioned.

  The polyisocyanate used in the urethanization reaction is obtained by hydrogenating aromatic methylene diisocyanates, hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate. Diisocyanates (for example, diisocyanates such as hydrogenated tolylene diisocyanate and hydrogenated xylylene diisocyanate), di- or tri-isocyanates such as triphenylmethane triisocyanate and dimethylene triphenyl triisocyanate, and a diisocyanate obtained Polyisocyanate etc. are mentioned.

  As the polyols used for the reaction with the polyisocyanate, polyester polyols, polyether polyols and the like can be used in addition to aromatic, aliphatic and alicyclic polyols. Aliphatic and alicyclic polyols include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, trimethylol ethane, trimethylol propane, ditriol. Examples include methylolpropane, pentaerythritol, dipentaerythritol, dimethylolheptane, dimethylolpropionic acid, dimethylolbutanoic acid, glycerin, and hydrogenated bisphenol A.

  The polyester polyol is obtained by a dehydration condensation reaction between the polyol and a polybasic carboxylic acid or an anhydride thereof. Polybasic carboxylic acids or their anhydrides include (anhydrous) succinic acid, adipic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, (anhydrous) trimellitic acid, (anhydrous) pyromellitic acid, hexahydro (anhydrous) ) Phthalic acid, (anhydrous) phthalic acid, isophthalic acid, terephthalic acid and the like.

  As said polyether polyol, the polyoxyalkylene modified polyol obtained by reaction of the said polyols or dihydroxybenzenes and alkylene oxide other than polyalkylene glycol is mentioned.

  The polyfunctional polyester (meth) acrylate oligomer can be obtained by a dehydration condensation reaction of (meth) acrylic acid, polybasic carboxylic acid or anhydride thereof and polyol. Polybasic carboxylic acids or anhydrides used in the dehydration condensation reaction include (anhydrous) succinic acid, adipic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, (anhydrous) trimellitic acid, (anhydrous) pyrone Examples include merit acid, hexahydro (anhydride) phthalic acid, (anhydrous) phthalic acid, isophthalic acid, terephthalic acid and the like. Examples of the polyol used for the dehydration condensation reaction include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, trimethylolethane, trimethylolpropane, Examples include ditrimethylolpropane, pentaerythritol, dipentaerythritol, dimethylolheptane, dimethylolpropionic acid, dimethylolbutanoic acid, glycerin, and hydrogenated bisphenol A.

  Moreover, a polyfunctional epoxy (meth) acrylate oligomer can be obtained by addition reaction of polyglycidyl ether and (meth) acrylic acid. Examples of the polyglycidyl ether include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and bisphenol A diglycidyl ether.

Among the (meth) acrylic compounds described above, for example, (meth) acrylic compounds having a structure represented by the following formulas (12) to (15) have a cured product obtained by curing having an elastic modulus of 3000 MPa or more. In addition, when combined with a cationic curable compound, particularly an alicyclic epoxy compound, it is preferable because of its excellent adhesion to a polarizing film. In the following formulas (12) and (13), R ₁₉ and R ₂₀ each independently represent a (meth) acryloyloxy group or a (meth) acryloyloxyalkyl group, wherein the alkyl has 1 to 1 carbon atoms. And R ₂₁ represents hydrogen or a hydrocarbon group having 1 to 10 carbon atoms; in the following formula (14), R ₂₂ , R ₂₃ and R ₂₄ each independently represent a (meth) acryloyloxy group. In the following formula (15), R ₂₅ represents a hydroxyl group or a (meth) acryloyloxy group.

In the above formulas (12) and (13), R ₁₉ and R ₂₀ each independently represent a (meth) acryloyloxy group or a (meth) acryloyloxyalkyl group. When R ₁₉ or R ₂₀ is a (meth) acryloyloxyalkyl group, the alkyl may be linear or branched and can have 1 to 10 carbon atoms, but generally has 1 to 1 carbon atoms. About 6 is sufficient. In the formula (13), R ₂₁ is hydrogen or a hydrocarbon group having 1 to 10 carbon atoms, and the hydrocarbon group may be linear or branched, and can typically be an alkyl group. . In this case, it is generally sufficient for the alkyl group to have about 1 to 6 carbon atoms.

The compound represented by the formula (12) is a di (meth) acrylate derivative of hydrogenated dicyclopentadiene or tricyclodecane dialkanol, and specific examples thereof are those exemplified above. Dicyclopentadienyl di (meth) acrylate [in the formula (12), R ₁₉ = R ₂₀ = (meth) acryloyloxy group compound], tricyclodecane dimethanol di (meth) acrylate [in the formula (12) R ₁₉ = R ₂₀ = (meth) acryloyloxymethyl group compound] and the like.

The compound represented by the formula (13) is a di (meth) acrylate derivative of dioxane glycol or dioxane dialkanol, and specific examples thereof include those exemplified above, but 1,3-dioxane-2. , 5-diyldi (meth) acrylate [also known as dioxane glycol di (meth) acrylate, compound of formula (13), R ₁₉ = R ₂₀ = (meth) acryloyloxy group, R ₂₁ = H], hydroxypivalaldehyde (Meth) acrylate [Chemical name: 2- (2-hydroxy-1,1-dimethylethyl) -5-ethyl-5-hydroxymethyl-1,3-dioxane] in (13), R ₁₉ = (meth) acryloyloxy methyl group, R ₂₀ = 2- (meth) acryloyloxy 1,1-dimethylethyl group, a compound of R ₂₁ = ethyl group], and the like.

  The compound represented by the formula (14) is triacrylate or trimethacrylate of 1,3,5-tris (2-hydroxyethyl) isocyanurate. The compound represented by the formula (15) is pentaerythritol tri- or tetra- (meth) acrylate. Specific examples thereof include pentaerythritol tri (meth) acrylate and pentaerythritol tetra (meth) acrylate. Can be mentioned.

  When the active energy ray-curable resin composition used in the present invention contains a radical curable compound (for example, a (meth) acrylic compound having one or more (meth) acryloyl groups in the molecule), the content thereof The rate is preferably 30 to 70% by weight, more preferably 35 to 65% by weight, and particularly preferably 40 to 60% by weight in the active energy ray-curable compound. When the content of the radical curable compound is less than 30% by weight, the optical performance tends to decrease due to yellowing of the cured film. When the content exceeds 70% by weight, the adhesion to the polarizing film is poor. There is a tendency to decrease.

  When the active energy ray-curable resin composition used in the present invention contains a radical curable compound, it is preferable that a radical photopolymerization initiator is blended in the active energy ray-curable resin composition. The radical photopolymerization initiator is not particularly limited as long as it can start curing of the radical curable compound by irradiation with active energy rays, and a conventionally known one can be used. Specific examples of the radical photopolymerization initiator are not particularly limited. For example, acetophenone, 3-methylacetophenone, benzyldimethyl ketal, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropane-1- Acetophenone-based initiators including ON, 2-methyl-1- [4- (methylthio) phenyl-2-morpholinopropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one; Benzophenone initiators such as benzophenone, 4-chlorobenzophenone, 4,4'-diaminobenzophenone, benzoin ether initiators including benzoinpropyl ether and benzoin ethyl ether; thioxanthones such as 4-isopropylthioxanthone Initiator Other, it is xanthone, fluorenone, camphor quinone, benzaldehyde, anthraquinone, such as.

  The compounding quantity of radical photopolymerization initiator is 0.5-20 weight part normally with respect to 100 weight part of radical type curable compounds, Preferably it is 1-6 weight part. When the blending amount of the photo radical polymerization initiator is less than 0.5 parts by weight with respect to 100 parts by weight of the radical curable compound, curing becomes insufficient, and mechanical strength and adhesion between the protective layer and the polarizing film are reduced. Tend to decrease. Moreover, when the compounding quantity of radical photopolymerization initiator exceeds 20 weight part with respect to 100 weight part of radical type curable compounds, the ionic substance in hardened | cured material will increase, and the hygroscopic property of hardened | cured material will become high. The durability performance may be reduced.

  In the present invention, the active energy ray-curable resin composition comprises both an epoxy compound and a (meth) acrylic compound having one or more (meth) acryloyloxy groups in the molecule as the active energy ray curable compound. It is preferable to include. Among them, the active energy ray-curable resin composition has one alicyclic epoxy compound as an active energy ray-curable compound and one in a molecule in which the elastic modulus of a cured product obtained by curing is 3000 MPa or more. It is more preferable to include both of the above (meth) acrylic compounds having a (meth) acryloyloxy group. By using both an epoxy compound and a (meth) acrylic compound having one or more (meth) acryloyloxy groups in the molecule as the active energy ray curable compound, the viscosity of the active energy ray curable resin composition And the curing speed, and the surface protective properties of the resulting protective layer, adhesion to the polarizing film, and elastic modulus can be adjusted more easily, and the hardness and mechanical strength are excellent. It becomes possible to obtain a protective layer capable of effectively suppressing shrinkage of the polarizing film under humidity. In addition, it is possible to provide a polarizing plate that can impart high adhesion to the protective layer and is excellent in moisture and heat resistance.

  When an epoxy compound and a (meth) acrylic compound having one or more (meth) acryloyloxy groups in the molecule are used in combination, one or more (meth) acryloyl in the molecule in the total amount of these compounds The content of the (meth) acrylic compound having an oxy group is preferably 30 to 70% by weight, more preferably 35 to 65% by weight, and particularly preferably 40 to 60% by weight. When the content is less than 30% by weight, the contraction rate of the polarizing plate may increase. Moreover, when the said content rate exceeds 70 weight%, the adhesiveness of a polarizing film and a protective layer may not be enough.

  Next, the fine particles contained in the active energy ray curable resin composition will be described. By adding fine particles to the active energy ray-curable resin composition, the hardness and mechanical strength of the protective layer obtained can be further improved. Thereby, the capability to suppress shrinkage | contraction of a polarizing film under high temperature and high humidity can further be improved. Examples of the fine particles include inorganic fine particles, organic fine particles, and inorganic / organic hybrid fine particles. Since the protective layer is preferably optically transparent, it is preferable to use fine particles that do not inhibit the optical transparency of the protective layer, such as not causing light scattering.

  The inorganic fine particles are not particularly limited, but for example, metal oxide fine particles such as silica fine particles, alumina fine particles, tin oxide fine particles, antimony oxide fine particles, indium oxide fine particles; tin oxide-antimony composite oxide fine particles, indium oxide-tin composite Examples thereof include composite oxide fine particles such as oxide fine particles. Among these, silica fine particles are preferably used because the material itself has a low refractive index and high strength. The silica fine particles may have a hydroxyl group on the surface. Examples of the organic fine particles include fine particles made of polystyrene resin, acrylic resin, organic silicone resin, polycarbonate resin, and the like. Examples of the inorganic / organic hybrid fine particles include silica fine particles having a functional group such as an epoxy group, a (meth) acryloyloxy group, and a vinyl group on the surface. Silica fine particles having a reactive functional group such as a hydroxyl group, an epoxy group, a (meth) acryloyloxy group, or a vinyl group on the surface are preferably used from the viewpoint of reacting with an active energy ray-curable compound and crosslinking.

  The particle diameter of the fine particles measured by the BET method or the dynamic light scattering method (DLS method) is preferably 100 nm or less, and more preferably 70 nm or less. When the particle diameter of the fine particles exceeds 100 nm, an optically transparent protective layer tends to be not obtained. The particle size is usually 3 nm or more.

  The inorganic fine particles may be added to the active energy ray-curable resin composition as solid fine particles, or may be added as a colloidal material dispersed in a solvent. As the solvent, an organic solvent is preferably used because drying can be performed relatively easily. Examples of inorganic fine particles dispersed in an organic solvent preferably used in the present invention include colloidal silica. The silica concentration in the colloidal silica is not particularly limited, and a commercially available product, for example, about 20 to 40% by weight can be used. As for colloidal silica, only 1 type may be used and 2 or more types may be used together.

  Examples of commercially available colloidal silica include “methanol silica sol” (manufactured by Nissan Chemical Industries, Ltd., silica particle size 10 to 15 nm, solid content 30% by weight), “MA- “ST-M” (manufactured by Nissan Chemical Industries, Ltd., silica particle size 20 to 25 nm, solid content 40% by weight), “OSCAL 1132” (manufactured by Catalyst Chemical Industries, Ltd., silica particle size 10 to 20 nm, solid content 30) "OSCAL 1232" (catalyst chemical industry Co., Ltd., silica particle size 10-20 nm, solid content 30-31 wt%); the organic solvent is n-propyl alcohol Certain “OSCAL 1332” (manufactured by Catalyst Kasei Kogyo Co., Ltd., silica particle size 10-20 nm, solid content 30-31 wt%); organic solvent is isopropyl alcohol "IPA-ST" (Nissan Chemical Industry Co., Ltd., silica particle size 10-15 nm, solid content 30 wt%), "OSCAL 1432" (Catalyst Chemical Industry Co., Ltd., silica particle size 10 "NBA-ST" (Nissan Chemical Industry Co., Ltd., silica particle size 10-15 nm, solid content 20% by weight), "OSCAL", organic solvent is n-butyl alcohol 1532 "(Catalyst Kasei Kogyo Co., Ltd., silica particle size 10-20 nm, solid content 30-31 wt%);" EG-ST "(Nissan Chemical Industry Co., Ltd., silica particles whose organic solvent is ethylene glycol) "OSCAL 1632" in which the organic solvent is ethyl cellosolve (manufactured by Catalyst Chemical Industry Co., Ltd., silica particle size of 10 to 20 nm, solid content of 30 to 31% by weight) “NPC-ST” (manufactured by Nissan Chemical Industries, silica particle size 10 to 15 nm, solid content 30% by weight); the organic solvent is dimethylacetamide “DMAC- ST ”(manufactured by Nissan Chemical Industries, Ltd., silica particle size 10-15 nm, solid content 20 wt%),“ DMAC-ST-ZL ”(manufactured by Nissan Chemical Industries, Ltd., silica particle size 70-100 nm, solid content) 20% by weight); “XBA-ST” (manufactured by Nissan Chemical Industries, silica particle size 10-15 nm, solid content 30% by weight); the organic solvent is a mixture of xylene and n-butyl alcohol; the organic solvent is methyl “MIBK-ST” which is isobutyl ketone (manufactured by Nissan Chemical Industries, Ltd., silica particle size 10 to 15 nm, solid content 30% by weight); the organic solvent is methyl ethyl ketone “ “MEK-ST” (manufactured by Nissan Chemical Industries, silica particle size 10-15 nm, solid content 30% by weight), “SP-1120” (manufactured by Konishi Chemical Industry Co., Ltd., silica particle size 15-20 nm, solid content) 5-10% by weight), “SP-6120” (manufactured by Konishi Chemical Co., Ltd., silica particle size 15-20 nm, solid content 5-10% by weight); “Snowtex 20” in which the dispersion medium is water, “Snowtex C” (manufactured by Nissan Chemical Industries, Ltd., silica particle size 10-20 nm) and the like are included. It can be preferably used.

  Moreover, as a commercial item of solid silica fine particles, for example, those sold by Nippon Aerosil Co., Ltd. as “AEROSIL” series such as “AEROSIL 50”, “AEROSIL 130”, “Nipsil E 150K”, Examples of the “Nipsil” series such as “Nipsil E 200” include those sold by Nippon Silica Kogyo Co., Ltd., and these can also be suitably used.

  The fine particles are preferably added in an amount of 5 to 250 parts by weight, more preferably 10 to 100 parts by weight based on 100 parts by weight of the active energy ray curable compound contained in the active energy ray curable resin composition. is there. When the addition amount of the fine particles is less than 5 parts by weight with respect to 100 parts by weight of the active energy ray-curable compound, the improvement in the hardness of the protective layer due to the addition of the fine particles may not be sufficient. On the other hand, when the addition amount of fine particles exceeds 250 parts by weight with respect to 100 parts by weight of the active energy ray-curable compound, the adhesion between the polarizing film and the protective layer may be lowered. Moreover, when the addition amount of the fine particles exceeds 250 parts by weight, the dispersion stability of the fine particles in the active energy ray-curable resin composition may be decreased, or the viscosity of the resin composition may be excessively increased. .

  The active energy ray-curable resin composition includes an active energy ray-curable compound, fine particles, and a photocationic polymerization initiator, and a photo radical polymerization initiator that is blended when a radical curable compound is included. For example, other components such as a solvent may be included.

  As a method of forming a protective layer on one side or both sides of the polarizing film, for example, the following method can be mentioned. First, for example, the active energy ray-curable resin composition is applied onto a polyethylene terephthalate film (PET film). Then, after drying for removing the solvent as necessary, a polarizing film is formed so that the PET film having a coating film made of the active energy ray-curable resin composition becomes a bonding surface. Paste to. Under the present circumstances, when laminating | stacking a protective layer on both surfaces of a polarizing film, two PET films which have a coating film are produced, and the said 2 PET film is bonded on both surfaces of a polarizing film. Next, this laminate is irradiated or heated with active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, thereby curing the coating film made of the active energy ray-curable resin composition to form a protective layer. Form. Finally, the PET film is peeled off to obtain a polarizing plate having a protective layer on one side or both sides of the polarizing film. The thickness of the protective layer is preferably as thin as possible in view of thinness and lightness. However, if the thickness is too thin, the polarizing film cannot be sufficiently protected, and handling properties are lacking. Therefore, the thickness of the protective layer is preferably about 1 to 35 μm.

  It is also possible to apply and cure the active energy ray-curable resin composition directly on the polarizing film, but the active energy ray-curable resin composition contains a solvent and is cured after a drying step. When making it, the above-described method is preferable from the viewpoint of preventing the polarizing film from being eroded by the solvent or shrinking at the drying temperature. Moreover, when forming a protective layer on both surfaces of a polarizing film, the content component of the active energy ray curable resin composition for forming both protective layers may be the same, or may differ.

When curing by irradiation with active energy rays, the light source used is not particularly limited, but has a light emission distribution at a wavelength of 400 nm or less, such as a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, A black light lamp, a microwave excitation mercury lamp, a metal halide lamp, etc. can be used. The light irradiation intensity to the active energy ray-curable resin composition may vary depending on the composition, but the irradiation intensity in the wavelength region effective for activation of the photo radical polymerization initiator and / or the photo cationic polymerization initiator is 10 It is preferably ˜2500 mW / cm ² . When the light irradiation intensity to the active energy ray curable resin composition is less than 10 mW / cm ² , the reaction time becomes too long, and when it exceeds 2500 mW / cm ² , the heat radiated from the lamp and the active energy ray curable property. There is a possibility that yellowing of the active energy ray-curable resin composition or deterioration of the polarizing film may occur due to heat generation during polymerization of the resin composition. The light irradiation time to the active energy ray-curable resin composition is controlled for each composition and is not particularly limited, but the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is 10. It is preferably set to be ˜2500 mJ / cm ² . If the integrated light amount to the active energy ray-curable resin composition is less than 10 mJ / cm ² , the generation of active species derived from the polymerization initiator is not sufficient, and the resulting protective layer may be insufficiently cured. is there. On the other hand, if the integrated light quantity exceeds 2500 mJ / cm ² , the irradiation time becomes very long, which is disadvantageous for improving productivity. In addition, it is preferable that irradiation of an active energy ray is performed in the range in which various performances, such as the polarization degree and transmittance | permeability of a polarizing film, do not fall.

<Optical member and liquid crystal display device>
The optical member of the present invention comprises a laminate of the polarizing plate and the optical functional layer, and specifically has a structure in which an optical functional layer is provided on the protective layer of the polarizing plate. The optical functional layer is not particularly limited, and a conventionally known layer can be used. Specific examples of the optical functional layer include, for example, a reflective layer, a transflective reflective layer, a light diffusing layer, a retardation plate, a light collecting plate, and a brightness enhancement film.

  The reflective layer can be formed, for example, by providing a foil or a vapor deposition film made of a metal such as aluminum on the protective layer of the polarizing plate. The transflective reflective layer can be formed by forming a reflective mirror as a half mirror, or providing a reflective plate containing a pearl pigment or the like and exhibiting light transmittance on the protective layer. The light diffusion layer can be formed by a method of performing a mat treatment on the protective layer, a method of applying a resin containing fine particles, a method of bonding a film containing fine particles, and the like.

  The retardation plate is used for the purpose of compensation of retardation by a liquid crystal cell, for example, a birefringent film made of a stretched film of various plastics, a film in which a discotic liquid crystal or a nematic liquid crystal is oriented and fixed. And those having the above-mentioned liquid crystal layer formed on a film substrate. In this case, a cellulose-based film such as triacetyl cellulose is preferably used as the film substrate that supports the oriented liquid crystal layer.

  The light collector is used for the purpose of optical path control and can be formed as a prism array sheet, a lens array sheet, or a dot-attached sheet.

  The brightness enhancement film is used for the purpose of improving the brightness in a liquid crystal display device or the like. For example, a plurality of thin film films having different refractive index anisotropies are laminated to produce anisotropy in reflectance. And a reflection-type polarization separation sheet designed in the above, a cholesteric liquid crystal polymer alignment film, and a circular polarization separation sheet in which the alignment liquid crystal layer is supported on a film substrate.

  The optical function layer may be used alone or in combination of two or more. The bonding of the optical functional layer to the protective layer and the bonding of the optical functional layers can be performed using an adhesive or a pressure-sensitive adhesive.

  The polarizing plate or optical member of the present invention can be suitably applied to a liquid crystal display device. Under the present circumstances, the polarizing plate or optical member of this invention is arrange | positioned at the one side or both surfaces of a liquid crystal cell. The polarizing plates or optical members provided on both sides of the liquid crystal cell may be the same or different.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited by these examples. In the examples, “parts” and “%” representing the amount used or content are based on weight unless otherwise specified.

(Production Example 1: Production of polarizing film)
A 75 μm-thick polyvinyl alcohol film (average polymerization degree: 1700, saponification degree: 99.9 mol% or more) was subjected to uniaxial stretching at a draw ratio of 5 times, and iodine and potassium iodide were kept in a tension state. It was immersed for 60 seconds in the aqueous solution containing (iodine: potassium iodide: water = 0.05: 5: 100 (weight ratio)). Next, it is immersed in a 65 ° C. aqueous solution containing potassium iodide and boric acid (potassium iodide: boric acid: water = 2.5: 7.5: 100 (weight ratio)) for 300 seconds to perform boric acid treatment. It was. Next, after washing with pure water at 25 ° C. for 20 seconds and drying at 50 ° C., a polarizing film in which iodine was adsorbed and oriented on a uniaxially stretched polyvinyl alcohol resin film was obtained.

(Production Example 2: Preparation of active energy ray-curable resin composition I)
First, the following components were mixed to obtain an active energy ray-curable resin composition A.

3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (Daicel Chemical Industries, Celoxide 2021P) 35 parts Bis (3-ethyl-3-oxetanylmethyl) ether (Toagosei Co., Ltd., Aron) Oxetane OXT-221) 15 parts 4-hydroxybutyl acrylate glycidyl ether (Nippon Kasei Co., Ltd., 4HBAGE) 25 parts Epoxy acrylate (Nippon Iupika Co., Ltd. Neopol SK-02-500)
25 parts 2-hydroxy-2-methyl-1-phenylpropan-1-one (Ciba Specialty Chemicals, DAROCUR 1173, photoradical polymerization initiator)
2.25 parts 4,4′-bis [diphenylsulfonio] diphenyl sulfide Bishexafluorophosphate-based photocationic polymerization initiator (manufactured by ADEKA, Adekaoptomer SP-150) 2.25 parts

  Next, 30 parts (in terms of solid content) of colloidal silica (Nissan Chemical Co., Ltd., MIBK-ST, silica particle size 10 to 15 nm) was mixed with 73 parts of the active energy ray-curable resin composition A. An active energy ray-curable resin composition I was obtained.

(Production Example 3: Preparation of active energy ray-curable resin composition II)
First, the following components were mixed to obtain an active energy ray-curable resin composition B.

3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (Daicel Chemical Industries, Celoxide 2021P) 35 parts Bis (3-ethyl-3-oxetanylmethyl) ether (Toagosei Co., Ltd., Aron) Oxetane OXT-221) 15 parts Tricyclodecane dimethanol diacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., A-DCP) 50 parts 2-hydroxy-2-methyl-1-phenylpropan-1-one (Ciba Specialty)・ Chemicals, DAROCUR 1173, photo radical polymerization initiator)
2.25 parts 4,4′-bis [diphenylsulfonio] diphenyl sulfide Bishexafluorophosphate-based photocationic polymerization initiator (manufactured by ADEKA, Adekaoptomer SP-150) 2.25 parts

  Next, 30 parts (in terms of solid content) of colloidal silica (Nissan Chemical Co., Ltd., MIBK-ST, silica particle size 10 to 15 nm) was mixed with 73 parts of the active energy ray-curable resin composition B. An active energy ray-curable resin composition II was obtained.

(Production Example 4: Preparation of active energy ray-curable resin composition III)
73 parts of active energy ray-curable resin composition B and 30 parts (in terms of solid content) of colloidal silica (manufactured by Nissan Chemical Co., Ltd., MEK-ST, silica particle size 10 to 15 nm) are mixed to obtain an active energy ray. A curable resin composition III was obtained.

(Production Example 5: Preparation of active energy ray-curable resin composition IV)
First, the following components were mixed to obtain an active energy ray-curable resin composition C.

3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (Daicel Chemical Industries, Celoxide 2021P) 35 parts Bis (3-ethyl-3-oxetanylmethyl) ether (Toagosei Co., Ltd., Alonoxetane) OXT-221) 15 parts Diacrylate of acetal compound of hydroxypivalaldehyde and trimethylolpropane (Shin-Nakamura Chemical Co., Ltd., A-DOG) 50 parts 2-hydroxy-2-methyl-1-phenylpropane- 1-one (Ciba Specialty Chemicals, DAROCUR 1173, photo radical polymerization initiator)
2.25 parts 4,4′-bis [diphenylsulfonio] diphenyl sulfide Bishexafluorophosphate-based photocationic polymerization initiator (manufactured by ADEKA, Adekaoptomer SP-150) 2.25 parts

  Next, 30 parts (solid content conversion) of colloidal silica (Nissan Chemical Co., Ltd. product, MEK-ST, silica particle size 10-15 nm) was mixed with 73 parts of active energy ray-curable resin composition B. An active energy ray-curable resin composition IV was obtained. In addition, said A-DOG (diacrylate of the acetal compound of a hydroxypivalaldehyde and a trimethylol propane) is a compound which has a structure of the following Formula (16).

(Production Example 6: Preparation of active energy ray-curable resin composition V)
First, the following components were mixed to obtain an active energy ray-curable resin composition D.

3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (Daicel Chemical Industries, Celoxide 2021P) 35 parts Bis (3-ethyl-3-oxetanylmethyl) ether (Toagosei Co., Ltd., Alonoxetane) OXT-221) 15 parts 1,3,5-tris (2-hydroxyethyl) isocyanurate triacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., A-9300) 50 parts 2-hydroxy-2-methyl-1- Phenylpropan-1-one (manufactured by Ciba Specialty Chemicals, DAROCUR 1173, photo radical polymerization initiator)
2.25 parts 4,4′-bis [diphenylsulfonio] diphenyl sulfide Bishexafluorophosphate-based photocationic polymerization initiator (manufactured by ADEKA, Adekaoptomer SP-150) 2.25 parts

  Next, 30 parts (in terms of solid content) of colloidal silica (Nissan Chemical Co., Ltd., MEK-ST, silica particle size 10 to 15 nm) is mixed with 73 parts of the active energy ray-curable resin composition D. The active energy ray-curable resin composition V was obtained.

(Production Example 7: Preparation of active energy ray-curable resin composition VI)
First, the following components were mixed to obtain an active energy ray-curable resin composition E.

3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (Daicel Chemical Industries, Celoxide 2021P) 35 parts Bis (3-ethyl-3-oxetanylmethyl) ether (Toagosei Co., Ltd., Alonoxetane) 15 parts pentaerythritol tetraacrylate (manufactured by Shin-Nakamura Chemical Co., Ltd., A-TMMT) 50 parts 2-hydroxy-2-methyl-1-phenylpropan-1-one (manufactured by Ciba Specialty Chemicals) , DAROCUR 1173, radical photopolymerization initiator)
2.25 parts 4,4′-bis [diphenylsulfonio] diphenyl sulfide Bishexafluorophosphate-based photocationic polymerization initiator (manufactured by ADEKA, Adekaoptomer SP-150) 2.25 parts

  Next, 30 parts (in terms of solid content) of colloidal silica (Nissan Chemical Co., Ltd., MEK-ST, silica particle size 10 to 15 nm) was mixed with 73 parts of the active energy ray-curable resin composition E. An active energy ray-curable resin composition VI was obtained.

(Production Example 8: Preparation of active energy ray-curable resin composition VII: for comparison)
73 parts of active energy ray-curable resin composition B and colloidal silica (manufactured by Konishi Chemical Industry Co., Ltd., SP-6120, silica particle size 15 to 20 nm, silica surface having vinyl group) 30 parts (solid content conversion) Were mixed to obtain an active energy ray-curable resin composition VII.

(Production Example 9: Preparation of active energy ray-curable resin composition VIII: for comparison)
73 parts of active energy ray-curable resin composition B, colloidal silica (manufactured by Konishi Chemical Industry Co., Ltd., SP-1120, silica particle size 15 to 20 nm, silica surface having vinyl group) 30 parts (solid content conversion) Were mixed to obtain an active energy ray-curable resin composition VIII.

<Example 1>
The film thickness after curing the active energy ray-curable resin composition I obtained in Production Example 2 on a polyethylene terephthalate (PET) film (Ester film E7002 manufactured by Toyobo Co., Ltd.) using a bar coater. It apply | coated so that it might become 20 micrometers. Next, the solvent was removed by drying at 80 ° C. for 3 minutes. Next, two PET films on which a coating film made of the active energy ray-curable resin composition was formed were pasted on both sides of the polarizing film obtained in Production Example 1 so that the coating film side became a bonding surface, respectively. Bonding was performed using an apparatus (manufactured by Fuji Pla Co., Ltd., LPA3301). Next, this laminated body was irradiated with ultraviolet rays with an integrated light quantity of 1500 mJ / cm ² by a D bulb manufactured by Fusion UV Systems, and the coating films on both sides were cured. Finally, the PET films on both sides were peeled off to obtain a polarizing plate having protective layers on both sides of the polarizing film, each having a protective layer (cured coating film) thickness of 20 μm. In addition, it was 70 micrometers when the thickness of the polarizing plate was measured using the film thickness measuring device (made by Nikon Corporation, ZC-101) (it is the same also about a following example and a comparative example).

<Example 2>
A polarizing plate was produced in the same manner as in Example 1, except that the active energy ray-curable resin composition II obtained in Production Example 3 was used instead of the active energy ray-curable resin composition I.

<Example 3>
A polarizing plate was produced in the same manner as in Example 1 except that the active energy ray-curable resin composition III obtained in Production Example 4 was used instead of the active energy ray-curable resin composition I.

<Example 4>
A polarizing plate was produced in the same manner as in Example 1 except that instead of the active energy ray-curable resin composition I, the active energy ray-curable resin composition IV obtained in Production Example 5 was used.

<Example 5>
A polarizing plate was produced in the same manner as in Example 1 except that instead of the active energy ray curable resin composition I, the active energy ray curable resin composition V obtained in Production Example 6 was used.

<Example 6>
A polarizing plate was produced in the same manner as in Example 1 except that instead of the active energy ray-curable resin composition I, the active energy ray-curable resin composition VI obtained in Production Example 7 was used.

<Comparative Example 1>
A polarizing plate was produced in the same manner as in Example 1 except that instead of the active energy ray curable resin composition I, the active energy ray curable resin composition A (not containing fine particles) was used.

<Comparative Example 2>
A polarizing plate was produced in the same manner as in Example 1 except that instead of the active energy ray curable resin composition I, the active energy ray curable resin composition B (not containing fine particles) was used.

<Comparative Example 3>
A polarizing plate was produced in the same manner as in Example 1 except that instead of the active energy ray curable resin composition I, the active energy ray curable resin composition C (containing no fine particles) was used.

<Comparative example 4>
A polarizing plate was produced in the same manner as in Example 1 except that the active energy ray-curable resin composition VII obtained in Production Example 8 was used instead of the active energy ray-curable resin composition I.

<Comparative Example 5>
A polarizing plate was produced in the same manner as in Example 1 except that the active energy ray-curable resin composition VIII obtained in Production Example 9 was used instead of the active energy ray-curable resin composition I.

  Table 1 summarizes the compositions of the active energy ray resin compositions used in Examples 1 to 6 and Comparative Examples 1 to 5 and the elastic modulus of the protective layer. Moreover, about the polarizing plate of Examples 1-6 and Comparative Examples 1-5, the adhesiveness test, the dimensional stability test, and the pencil hardness test were done. The results are shown in Table 2. Moreover, the elasticity modulus of the hardened | cured material obtained by hardening the (meth) acrylic-type compound used for preparation of an active energy ray resin composition was measured. The results are shown after the table.

  The elastic modulus and the measurement method for each test are as follows.

[Elastic modulus of protective layer]
On one side of a polyethylene terephthalate film (PET film), an active energy ray-curable resin composition for forming a protective layer is applied using a coating machine (manufactured by Daiichi Rika Co., Ltd., bar coater) The resin composition was cured by irradiating ultraviolet rays with an integrated light quantity of 1500 mJ / cm ² using a D bulb manufactured by Fusion UV Systems. Next, this cured product layer was cut into a 1 cm width × 8 cm length together with the PET film, and the PET film was peeled off to obtain a sample. Next, the long side portion of this sample was sandwiched between the upper and lower grips of an AUTOGRAPH AG-1S tester manufactured by Shimadzu Corporation so that the distance between the grips was 5 cm, and pulled at a pulling speed of 10 mm / min (the length of the sample From the initial straight line of the obtained stress-strain curve, the elastic modulus was calculated using data processing software (manufactured by Shimadzu Corporation, TRAPEZIUM2).

[Elastic modulus of cured product of (meth) acrylic compound]
The elasticity of the protective layer except that a curable resin composition comprising 50 parts of 4-hydroxybutyl acrylate glycidyl ether used in Production Example 2 and 2.25 parts of a radical photopolymerization initiator used in Production Example 2 is used. The modulus of elasticity of the cured product of the resin composition was measured in the same manner as the rate. The elastic modulus of the cured product was 150 MPa. Also, the epoxy acrylate used in Production Example 2, tricyclodecane dimethanol diacrylate used in Production Example 3, the diacrylate of an acetal compound of hydroxypivalaldehyde and trimethylolpropane used in Production Example 5, Production Example 6 For the triacrylate of 1,3,5-tris (2-hydroxyethyl) isocyanurate used in Example 1 and the pentaerythritol tetraacrylate used in Production Example 7, the elastic modulus of the cured product was measured in the same manner. As a result, the elastic modulus of the cured product was 1000, 3200, 3100, 3800, and 4300 MPa, respectively.

[Adhesion test]
After laminating the polarizing plate to the glass via an adhesive, 100 pieces of 1 mm square grids were cut on the surface of the protective layer with a cutter knife, a cellophane tape was applied thereto, and then a test was conducted to remove 100 pieces. Counted by the number of grids that remained unstripped. As a result, in any polarizing plate, the number of remaining grids was 100. In Table 2, “A” indicates that the number of remaining grids is 100/100.

[Dimensional stability test]
About each polarizing plate, the dimensional change after leaving still for 120 hours in a 85 degreeC dry environment was measured. That is, first, the polarizing plate was cut into a size of 8 cm × 8 cm, and bonded to glass via an adhesive to obtain a measurement sample. The sample was autoclaved for 1 hour at a temperature of 50 ° C. and a pressure of 5 kg / cm ² (490.3 kPa), and then left for 24 hours in an environment of a temperature of 23 ° C. and a relative humidity of 55%. The dimension in this state was defined as the initial dimension. Next, after allowing to stand in a dry environment at 85 ° C. for 120 hours, the dimensions in the machine direction (MD) and the transverse direction (TD) were measured using a two-dimensional dimension measuring device (manufactured by Nikon Corporation, NEXIV VMR-1207). The dimensional change rate was calculated from the following formula.
Dimension shrinkage (%) = {(Dimension after test−Initial dimension) / Initial dimension} × 100

  Table 2 shows the dimensional change rate in the MD direction. A when the dimensional change rate is less than 0.8% in absolute value, B when 0.8% or more and less than 1.1%, C when 1.3% or more and less than 1.3%, 1.3 % Or more was evaluated as D.

[Pencil hardness test]
The pencil hardness of the protective layer was measured in accordance with JIS K 5600-5-4 (scratch hardness (pencil method)). A sample of 2H or higher was A, a sample of less than 2H was B, and a sample of less than H was C.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

Claims (10)

A polarizing plate having a protective layer on at least one side of a polarizing film made of a polyvinyl alcohol-based resin,
The protective layer comprises a cured product of an active energy ray-curable resin composition containing an active energy ray-curable compound and fine particles,
The elastic modulus of the protective layer is 4000 to 10,000 MPa.   The polarizing plate according to claim 1, wherein the active energy ray-curable compound includes an epoxy compound having one or more epoxy groups bonded to an alicyclic ring.   The polarizing plate according to claim 2, wherein the active energy ray-curable compound further includes an oxetane compound.   The polarizing plate according to claim 2, wherein the active energy ray-curable compound further comprises a (meth) acrylic compound having one or more (meth) acryloyloxy groups in the molecule.   The (meth) acrylic compound having one or more (meth) acryloyloxy groups in the molecule has a cured product of 3000 MPa or more obtained by curing only the (meth) acrylic compound in the presence of a polymerization initiator. The polarizing plate according to claim 4, which is a (meth) acrylic compound that gives an elastic modulus of 5.   The polarizing plate according to claim 1, wherein the active energy ray-curable resin composition contains 5 to 250 parts by weight of the fine particles with respect to 100 parts by weight of the active energy ray-curable compound.   The polarizing plate according to claim 1, wherein the fine particles are silica particles having a particle size of 100 nm or less.   The polarizing plate according to claim 7, wherein the silica particles have one or more functional groups selected from the group consisting of a hydroxyl group, an epoxy group, a (meth) acryloyloxy group, and a vinyl group on a surface thereof.   The optical member which consists of a laminated body of the polarizing plate in any one of Claims 1-8, and an optical function layer.   The liquid crystal display device by which the polarizing plate in any one of Claims 1-8, or the optical member of Claim 9 is arrange | positioned at the single side | surface or both surfaces of a liquid crystal cell.