CN116723938A - Optical film and polarizing plate - Google Patents

Abstract

The present invention provides a (meth) acrylic resin optical film which can improve adhesion to a polarizing plate when placed in a high-temperature and high-humidity environment. The present invention provides an optical film comprising a resin layer containing a (meth) acrylic resin (A), (meth) acrylic resin (B) and an elastomer component (C), wherein the (meth) acrylic resin (A) has a higher syndiotacticity than the (meth) acrylic resin (B), and wherein when the content of the (meth) acrylic resin (A) in the resin layer is A (parts by mass) and the content of the elastomer component (C) is C (parts by mass), A/(A+C) < 0.6 is satisfied.

Description

Optical film and polarizing plate

Technical Field

The present invention relates to an optical film and a polarizing plate.

Background

A polarizing plate widely used in image display devices such as liquid crystal display devices and organic EL display devices generally has a structure in which a thermoplastic resin film is bonded to one or both surfaces of a polarizing plate as a protective film. JP-A2008-102274 (patent document 1) describes that an acrylic resin film can be used as a protective film.

Prior art literature

Patent literature

Patent document 1: japanese patent laid-open No. 2008-102274

Disclosure of Invention

Problems to be solved by the invention

There is room for improvement in adhesion between a polarizing plate and a (meth) acrylic resin film when the polarizing plate is placed in a high-temperature and high-humidity environment, in a polarizing plate having the (meth) acrylic resin film as a protective film.

The purpose of the present invention is to provide a (meth) acrylic resin-based optical film that can improve the adhesion.

Means for solving the problems

The present invention provides an optical film and a polarizing plate shown below.

[1] an optical film comprising a resin layer containing a (meth) acrylic resin (A), (meth) acrylic resin (B) and an elastomer component (C),

the (meth) acrylic resin (A) has a higher syndiotacticity than the (meth) acrylic resin (B),

when the content of the (meth) acrylic resin (a) in the resin layer is a (parts by mass) and the content of the elastomer component (C) is C (parts by mass), the resin layer satisfies the following formula [1]:

A/(A+C) < 0.6 [1]

The optical film according to [2], wherein when the content of the (meth) acrylic resin (B) in the resin layer is B (parts by mass), the following formula [2] is further satisfied:

A/(A+B) is more than or equal to 0.05 and less than or equal to 0.4 formula [2]

The optical film according to [ 1 ] or [2], wherein the elastomer component (C) is rubber particles.

The optical film according to any one of [ 1 ] to [ 3 ], further comprising a surface treatment layer laminated on the resin layer.

The optical film according to any one of [ 1 ] to [ 4 ], which is a protective film for a polarizing plate.

[ 6 ] A polarizing plate comprising, in order, a polarizing plate, an adhesive layer and the optical film according to any one of [ 1 ] to [ 5 ].

Effects of the invention

Provided is a (meth) acrylic resin optical film which can improve adhesion to a polarizing plate when placed in a high-temperature and high-humidity environment.

Drawings

Fig. 1 is a schematic cross-sectional view showing an example of the layer structure of the polarizing plate of the present invention.

Fig. 2 is a schematic cross-sectional view showing another example of the layer structure of the polarizing plate of the present invention.

Detailed Description

< optical film >

The optical film of the present invention (hereinafter also referred to as "optical film") is a film having a resin layer containing a (meth) acrylic resin (a), (meth) acrylic resin (B) and an elastomer component (C), and can be suitably used as a protective film for a polarizing plate.

Hereinafter, the (meth) acrylic resin (a), the (meth) acrylic resin (B), and the elastomer component (C) will also be referred to as "component (a)", "component (B)", and "component (C)", respectively.

The component (A) and the component (B) have at least different syndiotacticity, and specifically, the syndiotacticity of the component (A) is higher than that of the component (B).

In the present specification, the term "(meth) acrylic" means at least 1 selected from acrylic and methacrylic. The same applies to "(meth) acryl" and "(meth) acrylate".

When the content of the component (a) in the resin layer is a (parts by mass) and the content of the component (C) is C (parts by mass), the resin layer satisfies the following formula [1]:

A/(A+C) < 0.6 [1]

When the optical film of the present invention is bonded to a polarizing plate using an adhesive, the adhesion to the polarizing plate can be good, and thus the durability of the polarizing plate can be good. The optical film of the present invention can have good adhesion to a polarizing plate when adhered to the polarizing plate using an adhesive, particularly when exposed to a high-temperature and high-humidity environment, and thus can have good durability of the polarizing plate in a high-temperature and high-humidity environment.

[1] composition of optical film

The optical film may be a single-layer film, that is, may include the above-described resin layer. Alternatively, the optical film may include a layer other than the resin layer, and one example of the other layer is a surface treatment layer (coating layer).

[ 2 ] resin layer

The resin layer is a layer containing component (a), component (B) and component (C). The thickness of the resin layer is usually 5 μm or more and 200 μm or less, preferably 10 μm or more and 120 μm or less, more preferably 10 μm or more and 85 μm or less, still more preferably 15 μm or more and 65 μm or less. The thickness of the resin layer may be 60 μm or less or 50 μm or less. The reduction in thickness of the resin layer is advantageous for thinning of the polarizing plate, and further advantageous for thinning of an image display device or the like to which the polarizing plate is applied.

The resin layer may contain other resin components than the component (a) and the component (B).

Among them, from the viewpoints of heat resistance and toughness of the optical film, the total content of the component (a) and the component (B) in the resin component (excluding the component (C)) contained in the resin layer is preferably high, and the total content is preferably 80 mass% or more, more preferably 90 mass% or more, and still more preferably 95 mass% or more.

The component (a) is preferably a polymer containing methacrylate as a main monomer (containing 50 mass% or more). The component (A) may be a homopolymer of a methacrylate or a copolymer of a methacrylate and other copolymerized components.

The content of the structural unit derived from the methacrylate ester of the component (a) is preferably 90% by mass or more, more preferably 95% by mass or more, still more preferably 98% by mass or more, still more preferably 99% by mass or more, and particularly preferably 100% by mass.

In a preferred embodiment, component (a) is a homopolymer of methacrylate. In a preferred further embodiment, component (a) is a homopolymer of methyl methacrylate.

Examples of the methacrylate include methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, and 2-hydroxyethyl methacrylate. Component (a) may contain 1 or 2 or more structural units derived from methacrylate esters.

The methacrylate preferably comprises methyl methacrylate, more preferably methyl methacrylate.

Examples of the other copolymerizable component include:

acrylic esters such as ethyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate;

Hydroxyalkyl acrylates such as methyl 2- (hydroxymethyl) acrylate, methyl 2- (1-hydroxyethyl) acrylate, ethyl 2- (hydroxymethyl) acrylate, and n-butyl 2- (hydroxymethyl) acrylate, isobutyl, and tert-butyl 2- (hydroxymethyl) acrylate;

unsaturated acids such as methacrylic acid and acrylic acid;

halogenated styrenes such as chlorostyrene and bromostyrene;

substituted styrenes such as vinyl toluene and α -methylstyrene;

unsaturated nitriles such as acrylonitrile and methacrylonitrile;

unsaturated anhydrides such as maleic anhydride and citraconic anhydride;

unsaturated imides such as phenylmaleimide and cyclohexylmaleimide; and the like.

The other monofunctional monomers may be used alone or in combination of at least 2 kinds.

Multifunctional monomers may also be used as the other copolymerization components described above.

Examples of the polyfunctional monomer include compounds obtained by esterifying both terminal hydroxyl groups of ethylene glycol or an oligomer thereof with (meth) acrylic acid, such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, nonaethylene glycol di (meth) acrylate, and tetradecanediol di (meth) acrylate;

A compound obtained by esterifying both terminal hydroxyl groups of propylene glycol or an oligomer thereof with (meth) acrylic acid;

neopentyl glycol di (meth) acrylate, hexanediol di (meth) acrylate, butanediol di (meth) acrylate, and the like, which are obtained by esterifying the hydroxyl group of a diol with (meth) acrylic acid;

a compound obtained by esterifying both terminal hydroxyl groups of bisphenol A, alkylene oxide adducts of bisphenol A, or halogen substituents thereof with (meth) acrylic acid;

compounds obtained by esterifying polyhydric alcohols such as trimethylolpropane and pentaerythritol with (meth) acrylic acid, and compounds obtained by ring-opening addition of an epoxy group of glycidyl (meth) acrylate to the terminal hydroxyl group of the compounds;

a compound obtained by ring-opening addition of an epoxy group of glycidyl (meth) acrylate to a dibasic acid such as succinic acid, adipic acid, terephthalic acid, phthalic acid, or a halogen substituent thereof, or an alkylene oxide adduct thereof;

aryl (meth) acrylates; aromatic divinyl compounds such as divinylbenzene; etc.

The weight average molecular weight Mw of the component (a) is, for example, 40000 to 150000, preferably 40000 to 120000, more preferably 50000 to 100000 from the viewpoints of heat resistance of the optical film, adhesion to the polarizing plate, and formability of the resulting film.

The molecular weight distribution (weight average molecular weight Mw/number average molecular weight Mn) of the component (a) is, for example, 1.01 to 1.8, preferably 1.03 to 1.5, more preferably 1.05 to 1.3, from the viewpoints of heat resistance of the optical film and adhesion to the polarizing plate.

Mw and Mn can be controlled by adjusting the type and/or amount of the polymerization initiator used in the preparation of the component (A). Mw and Mn can be measured by Gel Permeation Chromatography (GPC) (standard polystyrene conversion).

The glass transition temperature Tg of the component (a) is preferably 110 ℃ or higher and 160 ℃ or lower, more preferably 120 ℃ or higher and 150 ℃ or lower, and still more preferably 125 ℃ or higher and 140 ℃ or lower, from the viewpoint of improving the toughness of the optical film. Tg can be controlled by adjusting molecular weight, syndiotacticity, etc.

The syndiotacticity (rr) represented by the triad of the component (a) is, for example, 55% or more, preferably 60% or more, more preferably 65% or more, and even more preferably 70% or more from the viewpoint of improving the toughness of the optical film and the viewpoint of improving the heat resistance of the optical film. The syndiotacticity (rr) represented by the triad of the component (a) is usually 90% or less, or may be 85% or less.

The syndication (rr) expressed by the triad is the ratio of the two chains (diad ) of three consecutive structural units (triad ) to the racemate (denoted rr). The syndiotacticity (rr) (%) expressed in the triad is calculated as follows, i.e., in CDCL ₃ In the course of the measurement at 30℃C ¹ H-NMR spectrum, based on which the area (X) and 0.6 to 1.35 of the region of 0.6 to 0.95ppm were measured when TMS was set to 0ppmThe area (Y) of the ppm region was calculated by (X/Y). Times.100.

The component (a) having the syndiotacticity (rr) represented by the triad in the above-described range can be produced, for example, by the method described in japanese unexamined patent publication No. 2016/080124, and the proportion of the syndiotacticity (rr) represented by the triad can be increased by decreasing the temperature at the time of polymerization or by extending the polymerization time.

The component (B) may be, for example, a polymer containing a methacrylate as a main monomer (containing 50 mass% or more), and is preferably a copolymer of a methacrylate and another copolymerization component. In a preferred embodiment, component (B) is a copolymer comprising structural units derived from methyl methacrylate. In a preferred further embodiment, component (B) is a copolymer comprising structural units derived from methyl methacrylate and structural units derived from methyl acrylate.

Examples of the other copolymerizable component other than methyl acrylate include compounds exemplified as the methacrylate ester and other copolymerizable components for component (A).

The weight average molecular weight Mw of the component (B) is, for example, 40000 to 150000, preferably 40000 to 130000, more preferably 50000 to 120000, from the viewpoints of heat resistance of the optical film, adhesion to the polarizing plate, and formability of the resulting film.

The molecular weight distribution (weight average molecular weight Mw/number average molecular weight Mn) of the component (B) is, for example, 1.01 to 2.5, preferably 1.03 to 2.4, more preferably 1.05 to 2.3, from the viewpoints of heat resistance of the optical film and adhesion to the polarizing plate.

Mw and Mn can be controlled by adjusting the type and/or amount of the polymerization initiator used in the preparation of the component (B). Mw and Mn can be measured by Gel Permeation Chromatography (GPC) (standard polystyrene conversion).

The glass transition temperature Tg of the component (B) is preferably 80 ℃ or more and 140 ℃ or less, more preferably 90 ℃ or more and 130 ℃ or less, and still more preferably 90 ℃ or more and less than 125 ℃. Tg can be controlled by adjusting molecular weight, syndiotacticity, etc.

The triad of component (B) represents a lower syndication (rr) than the syndication of component (a). The syndiotacticity (rr) represented by the triad of the component (B) is, for example, 25% or more and 60% or less, preferably 30% or more and 55% or less, and more preferably 40% or more and less than 55%.

The component (B) can be prepared, for example, by referring to the method described in JP 2009-145397A and JP 2021-155698A. Component (B) may also be a compound prepared by free radical polymerization.

The resin layer contains component (C). The inclusion of component (C) is advantageous in improving the toughness of the optical film and the adhesion to the polarizing plate. The component (C) may be rubber particles.

The rubber particles are rubber elastomer particles including a layer exhibiting rubber elasticity. The rubber particles may be particles including only a layer exhibiting rubber elasticity, or may be particles having a multilayer structure in which the layer exhibiting rubber elasticity is provided and other layers are provided. Examples of the rubber elastomer include olefin-based elastic polymers, diene-based elastic polymers, styrene-diene-based elastic copolymers, and acrylic-based elastic polymers. Among them, acrylic elastic polymers are preferably used from the viewpoints of light resistance and transparency of the optical film.

The acrylic elastic polymer may be a polymer mainly composed of an alkyl acrylate, that is, a polymer containing 50 mass% or more of a structural unit derived from an alkyl acrylate based on the total monomer amount. The acrylic elastic polymer may be a homopolymer of an alkyl acrylate or a copolymer containing 50 mass% or more of a structural unit derived from an alkyl acrylate and 50 mass% or less of a structural unit derived from another polymerizable monomer.

As the alkyl acrylate constituting the acrylic elastic polymer, an alkyl acrylate having 4 to 8 carbon atoms in the alkyl group is generally used.

Examples of the other polymerizable monomer include alkyl methacrylates such as methyl methacrylate and ethyl methacrylate; styrene monomers such as styrene and alkylstyrene; monofunctional monomers such as unsaturated nitriles, e.g., acrylonitrile and methacrylonitrile, and unsaturated carboxylic acid alkenyl esters such as allyl (meth) acrylate and methallyl (meth) acrylate; diallyl maleate and other dibasic acid dienyl esters; polyfunctional monomers such as unsaturated carboxylic acid diesters of glycols such as alkylene glycol di (meth) acrylate.

The rubber particles containing the acrylic elastic polymer are preferably particles having a multilayer structure of layers of the acrylic elastic polymer. Specifically, examples of the particles include particles having a two-layer structure including a hard polymer layer mainly composed of an alkyl methacrylate on the outer side of a layer of an acrylic elastic polymer, and particles having a three-layer structure including a hard polymer layer mainly composed of an alkyl methacrylate on the inner side of a layer of an acrylic elastic polymer. The alkyl methacrylate is preferably methyl methacrylate.

The rubber particles preferably have an average particle diameter ranging from 10nm to 350nm inclusive up to the rubber elastomer layer (layer of the acrylic elastic polymer) contained therein. The average particle diameter in this range is advantageous for improving the toughness of the optical film and the adhesion with the polarizing plate. The average particle diameter is more preferably 30nm or more, still more preferably 50nm or more, still more preferably 320nm or less, still more preferably 300nm or less.

The average particle diameter of the rubber particles up to the rubber elastomer layer (layer of the acrylic elastic polymer) can be measured as follows. That is, when such rubber particles are mixed with a (meth) acrylic resin to form a film and the cross section thereof is dyed with an aqueous solution of ruthenium oxide, only the rubber elastomer layer is dyed to observe a substantially circular shape, and the (meth) acrylic resin of the mother layer is not dyed. Thus, a sheet was prepared from the thus-stained film section using an ultra-thin microtome or the like, and observed with an electron microscope. Thereafter, 100 dyed rubber particles were randomly extracted, and the respective particle diameters (diameters up to the rubber elastomer layer) were calculated, and then the number average value was used as the average particle diameter. The average particle diameter obtained by the measurement according to this method is a number average particle diameter.

In the case of rubber particles in which the outermost layer is a hard polymer mainly composed of methyl methacrylate and in which a rubber elastomer layer (layer of an acrylic elastic polymer) is enclosed, if the rubber particles are mixed into a matrix (meth) acrylic resin, the outermost layer of the rubber particles is mixed with the matrix (meth) acrylic resin. Therefore, when the cross section is stained with ruthenium oxide and observed by an electron microscope, the rubber particles are observed as particles from which the outermost layer is removed. Specifically, in the case of a rubber particle having a two-layer structure in which the inner layer is an acrylic elastic polymer and the outer layer is a hard polymer mainly composed of methyl methacrylate, the acrylic elastic polymer of the inner layer is partially dyed and is observed as a particle having a single-layer structure. In the case of the rubber particles having a three-layer structure in which the innermost layer is a hard polymer mainly composed of methyl methacrylate, the intermediate layer is an acrylic elastic polymer, and the outermost layer is a hard polymer mainly composed of methyl methacrylate, the particles having a two-layer structure in which the central portion of the particles as the innermost layer is not dyed, but only the acrylic elastic polymer portion of the intermediate layer is dyed are observed.

The resin layer satisfies the above formula [1]. In this way, the adhesion to the polarizer can be improved when the optical film is adhered to the polarizer using the adhesive, and in particular, the adhesion to the polarizer can be improved when the optical film is adhered to the polarizer using the adhesive even when the optical film is exposed to a high-temperature and high-humidity environment. The ratio a/(a+c) may be 0.55 or less, may be 0.50 or less, may be 0.45 or less, or may be 0.40 or less.

From the viewpoint of the adhesion, a/(a+c) is preferably 0.1 or more, more preferably 0.2 or more.

When the content of the component (B) is B (parts by mass), B is preferably larger than a.

The resin layer preferably further satisfies the following formula [2]:

A/(A+B) is more than or equal to 0.05 and less than or equal to 0.4 formula [2]

Satisfying the formula [2] is advantageous in improving the toughness of the optical film and the adhesion with the polarizing plate.

A/(A+B) is preferably 0.10 or more and 0.35 or less, more preferably 0.15 or more and 0.30 or less.

The content of the component (a) in the resin layer is preferably 1% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 40% by mass or less, still more preferably 10% by mass or more and 35% by mass or less, and still more preferably 15% by mass or more and 30% by mass or less, from the viewpoints of toughness of the optical film and adhesion to the polarizing plate.

The content of the component (B) in the resin layer is preferably 10 mass% or more and 95 mass% or less, more preferably 20 mass% or more and 90 mass% or less, still more preferably 30 mass% or more and 80 mass% or less, and still more preferably 40 mass% or more and 70 mass% or less, from the viewpoints of toughness of the optical film and adhesion to the polarizing plate.

The content of the component (C) in the resin layer is preferably 1% by mass or more and 50% by mass or less, more preferably 5% by mass or more and 40% by mass or less, still more preferably 10% by mass or more and 35% by mass or less, and still more preferably 15% by mass or more and 35% by mass or less, from the viewpoints of toughness of the optical film and adhesion to the polarizing plate.

The resin layer may contain other components than those described above as needed. Examples of the other components include lubricants, antiblocking agents, heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, impact modifiers, surfactants, and mold release agents.

When the tensile elastic modulus in the MD direction at 23℃is E23 (MD) and the tensile elastic modulus in the TD direction at 23℃is E23 (TD), the resin layer preferably satisfies the following formula [3]:

E23 (TD)/E23 (MD) of 0.5 to 1.5 [3]

E23 (TD)/E23 (MD) in the formula [3] may be 0.6 or more and 1.4 or less, or 0.7 or more and 1.3 or less, or 0.8 or more and 1.3 or less, or 0.9 or more and 1.2 or less, or 0.9 or more and 1.1 or less. E23 The units of (MD) and E23 (TD) are MPa.

In order to satisfy the above formula [3], the resin layer is preferably unstretched.

When the tensile elastic modulus in the MD direction at 80℃is E80 (MD) and the tensile elastic modulus in the TD direction at 80℃is E80 (TD), the resin layer preferably satisfies the following formula [4]:

e80 (TD)/E80 (MD) of 0.5 to 1.5 [4]

E80 (TD)/E80 (MD) in the formula [4] may be 0.6 or more and 1.4 or less, or 0.7 or more and 1.3 or less, or 0.8 or more and 1.3 or less, or 0.9 or more and 1.2 or less, or 0.9 or more and 1.1 or less. E80 The units of (MD) and E80 (TD) are MPa.

The resin layer preferably has an absorption energy (Charpy impact strength) of 140kJ/m as measured by the Charpy impact test ² The above is more preferably 160kJ/m ² The above is more preferably 170kJ/m ² The above is more preferably 180kJ/m ² The above is particularly preferably 200kJ/m ² The above. Charpy impact strength is generally 350kJ/m ² Hereinafter, it may be 300kJ/m ² The following is given. The Charpy impact test was performed in an environment having a temperature of 23℃and a relative humidity of 50% RH.

Setting the Charpy impact strength to the above range is advantageous in improving the adhesion between the polarizing plate and the optical film, and particularly in improving the adhesion between the polarizing plate and the optical film when placed in a high-temperature and high-humidity environment.

The tensile elastic modulus and the Charpy impact strength of the resin layer can be measured by the method described in one of examples described below.

[ 3 ] surface treatment layer

Examples of the surface treatment layer include a hard coat layer, an antiglare layer, an antireflection layer, a light diffusion layer, an antistatic layer, an antifouling layer, and a conductive layer, and a hard coat layer is preferable. The surface treatment layer may be 1 layer and have a plurality of functions, or may be a layer having, for example, a hard coat property and an antiglare property. A surface treatment layer (coating layer) is laminated on the resin layer, and is usually directly laminated on the resin layer. In a polarizing plate in which an optical film is bonded to a polarizing plate, the surface of a resin layer on which a surface treatment layer is laminated is generally the surface on the opposite side to the polarizing plate side.

The surface-treated layer may be a cured layer of a curable resin composition containing an active energy ray-curable compound. The active energy ray-curable compound is a compound that is polymerized and cured by irradiation with active energy rays such as ultraviolet rays and electron beams.

Examples of the active energy ray-curable compound include monofunctional, 2-functional, or 3-functional or more (meth) acrylate compounds. The active energy ray-curable compound may be used in an amount of 1 or 2 or more.

Examples of the monofunctional (meth) acrylate compound include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, ethyl (meth) acrylate, N-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, glycidyl (meth) acrylate, acryloylmorpholine, N-vinylpyrrolidone, tetrahydrofurfuryl acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isobornyl (meth) acrylate, isodecyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, cetyl (meth) acrylate, octadecyl (meth) acrylate, benzyl (meth) acrylate, 2-ethoxyethyl (meth) acrylate, 3-methoxybutyl (meth) acrylate, ethylcarbitol (meth) acrylate, phosphoric acid (meth) acrylate, ethylene oxide modified phosphoric acid (meth) acrylate, phenoxy (meth) acrylate, ethylene oxide modified phenoxy (meth) acrylate, propylene oxide modified phenoxy (meth) acrylate, nonylphenoxy (meth) acrylate, and nonylphenol (meth) acrylate Ethylene oxide modified nonylphenol (meth) acrylate, propylene oxide modified nonylphenol (meth) acrylate, methoxydiglycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypropanediol (meth) acrylate, 2- (meth) acryloyloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2- (meth) acryloyloxyethyl hydrophthalate, 2- (meth) acryloyloxypropyl hexahydrophthalate, 2- (meth) acryloyloxypropyl tetrahydrophthalate, dimethylaminoethyl (meth) acrylate, trifluoroethyl (meth) acrylate, tetrafluoropropyl (meth) acrylate, hexafluoropropyl (meth) acrylate, octafluoropropyl (meth) acrylate, adamantane derivative mono (meth) acrylates (e.g., adamantyl acrylate having a valence of 1 derived from adamantane diol), and the like.

Examples of the 2-functional (meth) acrylate compound include di (meth) acrylates such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, hexanediol di (meth) acrylate, nonanediol di (meth) acrylate, ethoxylated hexanediol di (meth) acrylate, propoxylated hexanediol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, neopentyl glycol di (meth) acrylate, ethoxylated neopentyl glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, isocyanuric acid di (meth) acrylate, hydroxypivalic acid neopentyl glycol di (meth) acrylate, adamantyl di (meth) acrylate, isobornyl di (meth) acrylate, dicyclopentane di (meth) acrylate, and tricyclodecane di (meth) acrylate.

Examples of the 3-functional or higher (meth) acrylate compound include trimethylolpropane tri (meth) acrylate, ethoxylated trimethylolpropane tri (meth) acrylate, propoxylated trimethylolpropane tri (meth) acrylate, tris 2-hydroxyethyl isocyanurate tri (meth) acrylate, glycerol tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol tri (meth) acrylate, ditrimethylolpropane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, ditrimethylolpropane penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, ditrimethylolpropane hexa (meth) acrylate, tripentaerythritol octa (meth) acrylate, tetrapentaerythritol deca (meth) acrylate, and polyfunctional (meth) acrylates in which some of these (meth) acrylates are substituted with alkyl groups, epsilon-caprolactone.

Further examples of the active energy ray-curable compound include oligomers and polymers such as urethane (meth) acrylate, isocyanurate (meth) acrylate, polyester-urethane (meth) acrylate, and epoxy (meth) acrylate.

Examples of the urethane (meth) acrylate include pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate hexamethylene diisocyanate urethane prepolymer, pentaerythritol triacrylate toluene diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate toluene diisocyanate urethane prepolymer, pentaerythritol triacrylate isophorone diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate isophorone diisocyanate urethane prepolymer, and the like.

The curable resin composition may further contain a thermoplastic resin. Examples of the thermoplastic resin include styrene resins, (meth) acrylic resins, vinyl acetate resins, vinyl ether resins, halogen-containing resins, alicyclic olefin resins, polycarbonate resins, polyester resins, polyamide resins, cellulose derivatives, silicone resins, and rubbers or elastomers.

The curable resin composition may further comprise a thermosetting resin. Examples of the thermosetting resin include phenol resins, urea resins, diallyl phthalate resins, melamine resins, guanamine resins, unsaturated polyester resins, polyurethane resins, epoxy resins, amino alkyd resins, melamine-urea cocondensation resins, silicone resins, and polysiloxane resins.

The curable resin composition may contain 1 or 2 or more photo radical polymerization initiators. Examples of the photo radical polymerization initiator include acetophenones, benzophenones, benzoates and benzoates of milbetone, such as benzoates, benzoates and acylphosphinoxides. The curable resin composition may further contain 1 or 2 or more photosensitizers. Examples of the photosensitizer include n-butylamine, triethylamine, and poly-n-butylphosphine.

The curable resin composition may further contain organic fine particles and inorganic fine particles. The organic fine particles may be fine particles containing at least one material selected from the group consisting of acrylic resins, polystyrene resins, styrene-acrylic copolymers, polyethylene resins, epoxy resins, silicone resins, polyvinylidene fluoride resins, and polyvinyl fluoride resins. Examples of the inorganic fine particles include Silica (SiO) ₂ ) Microparticles, alumina microparticles, titania microparticles, tin oxide microparticles, and antimony-doped tin oxide (abbreviation: ATO) fine particles, zinc oxide fine particles, and the like, and silica fine particles are preferable. The silica particles are preferably amorphous silica. Examples of the amorphous silica fine particles include fumed silica fine particles and colloidal silica. The silica particles may be surface-modified. The average primary particle diameter of the silica fine particles is preferably 200nm or less, more preferably 100nm or less. The lower limit of the average primary particles of the silica fine particles is not particularly limited, and may be, for example, 1nm or more.

The curable resin composition may contain 1 or 2 or more solvents. Examples of the solvent include alcohols (e.g., methanol, ethanol, propanol, isopropanol, n-butanol, sec-butanol, tert-butanol, benzyl alcohol, PGME, and ethylene glycol), ketones (e.g., acetone, methyl Ethyl Ketone (MEK), cyclohexanone, methyl isobutyl ketone, diacetone alcohol, cycloheptanone, and diethyl ketone), ethers (e.g., 1, 4-dioxane, dioxolane, diisopropyl ether dioxane, and tetrahydrofuran), aliphatic hydrocarbons (e.g., hexane), alicyclic hydrocarbons (e.g., cyclohexane), aromatic hydrocarbons (e.g., toluene, and xylene), halocarbons (e.g., dichloromethane and dichloroethane), esters (e.g., methyl formate, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, and ethyl lactate), cellosolves (e.g., methyl cellosolve, ethyl cellosolve, and butyl cellosolve), cellosolve acetates, sulfoxides (e.g., dimethyl sulfoxide), and amides (e.g., dimethylformamide and dimethylacetamide).

The solid content (total amount of active energy ray-curable compound, thermoplastic resin, and thermosetting resin) of the curable resin composition is, for example, 5 to 70 mass%, preferably 25 to 60 mass%.

The content of the photo radical polymerization initiator in the curable resin composition is preferably 0.5 parts by mass or more and 10 parts by mass or less relative to 100 parts by mass of the active energy ray-curable compound.

The thickness of the surface treatment layer such as a hard coat layer is, for example, 0.1 μm or more and 50 μm or less, preferably 0.5 μm or more and 30 μm or less, more preferably 1 μm or more and 20 μm or less, and still more preferably 1 μm or more and 10 μm or less.

< polarizing plate >

The term "polarizing plate" as used herein refers to an optical laminate comprising a polarizing plate and a thermoplastic resin film laminated on one or both surfaces thereof. In the polarizing plate, a polarizing plate and the thermoplastic resin film are laminated via an adhesive layer. The adhesive layer is a layer formed of an adhesive composition, and is, for example, a cured product layer of the adhesive composition.

The polarizing plate may include a film or layer other than the polarizing plate and the thermoplastic resin film.

The polarizing plate of the present invention comprises a polarizing plate, an adhesive layer, and the optical film of the present invention described above in this order. Typically, the polarizer is in contact with the adhesive layer, which is in contact with the optical film. Since the polarizing plate of the present invention uses the optical film of the present invention as a protective film for a polarizing plate, adhesion between the polarizing plate and the optical film can be improved, and thus durability of the polarizing plate can be improved. In the polarizing plate of the present invention, adhesion between the polarizing plate and the optical film can be improved even when exposed to a high-temperature and high-humidity environment, and durability in a high-temperature and high-humidity environment can be improved.

The polarizing plate of the present invention can be suitably used for image display devices such as liquid crystal display devices and organic EL devices.

[ 1 ] constitution of polarizing plate

Fig. 1 and 2 show an example of the layer structure of the polarizing plate of the present invention.

As shown in fig. 1, the polarizing plate of the present invention may include, in order, a polarizing plate 30, a 1 st adhesive layer 15, and a 1 st thermoplastic resin film 10 as the optical film of the present invention, that is, may include the polarizing plate 30 and the 1 st thermoplastic resin film 10 laminated and bonded to one surface thereof via the 1 st adhesive layer 15.

The primer layer may be interposed between the 1 st adhesive layer 15 and the 1 st thermoplastic resin film 10, or the 1 st adhesive layer 15 may be in direct contact with the 1 st thermoplastic resin film 10. Preferably, the polarizer 30 is in direct contact with the 1 st adhesive layer 15.

As shown in fig. 2, the polarizing plate of the present invention may include a polarizing plate 30, a 1 st thermoplastic resin film 10 as the optical film of the present invention described above laminated and bonded to one surface thereof via a 1 st adhesive layer 15, and a 2 nd thermoplastic resin film 20 laminated and bonded to the other surface of the polarizing plate 30 via a 2 nd adhesive layer 25.

The 1 st adhesive layer 15 is preferably in direct contact with the 1 st thermoplastic resin film 10. Preferably, the polarizer 30 is in direct contact with the 1 st adhesive layer 15. The 2 nd adhesive layer 25 is preferably in direct contact with the 2 nd thermoplastic resin film 20. Preferably, the polarizer 30 is in direct contact with the 2 nd adhesive layer 25.

The polarizing plate of the present invention is preferably incorporated into an image display device such that the 1 st thermoplastic resin film 10 side is the viewing side. That is, the optical film of the present invention is preferably a protective film laminated on the viewing side of the polarizing plate 30.

The polarizing plate of the present invention may include other layers (or films) than those described above, not limited to the examples of fig. 1 and 2. Examples of the other layer include an adhesive layer laminated on the outer surfaces of the 1 st thermoplastic resin film 10, the 2 nd thermoplastic resin film 20, and/or the polarizing plate 30; a release film (also referred to as a "release film") laminated to an outer surface of the adhesive layer; a protective film (also referred to as a "surface protective film") laminated on the outer surface of the 1 st thermoplastic resin film 10, the 2 nd thermoplastic resin film 20, and/or the polarizing plate 30; an optically functional film (or layer) laminated on the outer surfaces of the 1 st thermoplastic resin film 10, the 2 nd thermoplastic resin film 20, and/or the polarizing plate 30 via an adhesive layer and an adhesive layer.

[ 2 ] polarizer

The polarizing plate 30 is a film having a function of selectively transmitting linearly polarized light in a certain direction from natural light. Examples of the polarizing plate 30 include an iodine-based polarizing plate in which iodine as a dichroic dye is adsorbed and aligned to a polyvinyl alcohol-based resin film, a dye-based polarizing plate in which a dichroic dye as a dichroic dye is adsorbed and aligned to a polyvinyl alcohol-based resin film, and a coated polarizing plate in which a dichroic dye in a lyotropic liquid crystal state is coated, aligned, and immobilized. These polarizing plates are called absorption type polarizing plates because they selectively transmit linear polarized light in one direction from natural light and absorb linear polarized light in the other direction.

The polarizing plate 30 is not limited to an absorption type polarizing plate, and may be a reflection type polarizing plate that selectively transmits linear polarized light in one direction from natural light, reflects linear polarized light in the other direction, or scatters linear polarized light in the other direction, but an absorption type polarizing plate is preferable in view of excellent visibility when the polarizing plate is applied to an image display device or the like.

Among these, the polarizing plate 30 is more preferably a polyvinyl alcohol polarizing plate composed of a polyvinyl alcohol resin, and further preferably a polyvinyl alcohol polarizing plate in which a dichroic dye such as iodine or a dichroic dye is adsorbed and aligned to a polyvinyl alcohol resin film, and particularly preferably a polyvinyl alcohol polarizing plate (polyvinyl alcohol-iodine polarizing plate) in which iodine is adsorbed and aligned to a polyvinyl alcohol resin film.

The polyvinyl alcohol-based polarizing plate can be produced by a conventionally known method using a polyvinyl alcohol-based resin film (or layer).

The thickness of the polarizing plate 30 may be 30 μm or less, preferably 25 μm or less (for example, 20 μm or less, further 15 μm or less, further 10 μm or less, further 8 μm or less). The thickness of the polarizing plate 30 is usually 2 μm or more. Reducing the thickness of the polarizing plate 30 is advantageous for thinning the polarizing plate, and further advantageous for thinning an image display device or the like to which the polarizing plate is applied.

[ 3 ] No. 2 thermoplastic resin film

The 2 nd thermoplastic resin film 20 may be a film containing a light-transmissive (preferably optically transparent) thermoplastic resin, and may be a polyolefin resin containing a chain polyolefin resin (polyethylene resin, polypropylene resin, etc.), a cyclic polyolefin resin (norbornene resin, etc.), or the like; cellulose ester resins such as triacetyl cellulose and diacetyl cellulose; polyester resins such as polyethylene terephthalate, polyethylene naphthalate and polybutylene terephthalate; a polycarbonate resin; a film of (meth) acrylic resin or the like.

The 2 nd thermoplastic resin film 20 may be an optical film of the present invention.

When the 2 nd thermoplastic resin film 20 is a (meth) acrylic resin film, the resin components constituting the 2 nd thermoplastic resin film 20 may be different from the resin components constituting the optical film of the present invention in terms of composition or the like.

The 2 nd thermoplastic resin film 20 may be any one of a film which is not stretched, or a film which is uniaxially or biaxially stretched. The biaxial stretching may be simultaneous biaxial stretching in which the stretching is simultaneous in 2 stretching directions, or sequential biaxial stretching in which the stretching is followed by stretching in the 1 st direction and then stretching in the 2 nd direction different from the 1 st direction.

The 2 nd thermoplastic resin film 20 may be a protective film that serves to protect the polarizing plate 30, or may be a protective film having optical functions such as a retardation film. For example, a retardation film to which an arbitrary phase difference value is imparted can be produced by stretching a film containing the thermoplastic resin (uniaxial stretching, biaxial stretching, or the like), or forming a liquid crystal layer on the thermoplastic resin film.

The 2 nd thermoplastic resin film 20 may contain additives as needed. Examples of the additives include lubricants, antiblocking agents, heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, impact modifiers, surfactants, and mold release agents.

In one embodiment, the 1 st thermoplastic resin film 10 is the optical film of the present invention, and the 2 nd thermoplastic resin film 20 is a polyolefin resin film (preferably a cyclic polyolefin resin film), a cellulose ester resin, or a polyester resin film.

In another embodiment, the 1 st thermoplastic resin film 10 is the optical film of the present invention, and the 2 nd thermoplastic resin film 20 is a (meth) acrylic resin film. The (meth) acrylic resin film may be the optical film of the present invention.

The 2 nd thermoplastic resin film 20 may have a coating layer (surface treatment layer) such as a hard coat layer, an antiglare layer, an antireflection layer, a light diffusion layer, an antistatic layer, an antifouling layer, and a conductive layer on its outer surface (surface opposite to the polarizer 30).

The thickness of the 2 nd thermoplastic resin film 20 is usually 5 μm or more and 200 μm or less, preferably 10 μm or more and 120 μm or less, more preferably 10 μm or more and 85 μm or less, still more preferably 15 μm or more and 65 μm or less. The thickness of the 2 nd thermoplastic resin film 20 may be 60 μm or less or 50 μm or less. Reducing the thickness of the 2 nd thermoplastic resin film 20 is advantageous for thinning of the polarizing plate, and further advantageous for thinning of an image display device or the like to which the polarizing plate is applied.

(4) manufacturing of polarizing plate and adhesive layer

The 1 st thermoplastic resin film 10 as the optical film of the present invention is laminated and bonded on one surface of the polarizing plate 30 via the 1 st adhesive layer 15, whereby the polarizing plate having the configuration shown in fig. 1 can be obtained, and the 2 nd thermoplastic resin film 20 is further laminated and bonded on the other surface of the polarizing plate 30 via the 2 nd adhesive layer 25, whereby the polarizing plate having the configuration shown in fig. 2 can be obtained.

In the case of manufacturing a polarizing plate having both the 1 st thermoplastic resin film 10 and the 2 nd thermoplastic resin film 20 (hereinafter, these are also collectively referred to simply as "thermoplastic resin films"), these thermoplastic resin films may be laminated and bonded in stages one by one, or the thermoplastic resin films on both sides may be laminated and bonded at the same time.

The adhesive composition for forming the 1 st adhesive layer 15 and the 2 nd adhesive layer 25 includes an aqueous adhesive and an active energy ray-curable adhesive. The adhesive composition forming the 1 st adhesive layer 15 may be the same as or different from the adhesive composition forming the 2 nd adhesive layer 25.

The adhesive used for bonding the optical film and the polarizing plate of the present invention is preferably an active energy ray-curable adhesive.

As the aqueous adhesive, for example, a conventionally known adhesive composition using a polyvinyl alcohol resin or a urethane resin as a main component is given. The active energy ray-curable adhesive is an adhesive cured by irradiation with active energy rays such as ultraviolet rays, visible rays, electron beams, and X-rays. When an active energy ray-curable adhesive is used, the adhesive layer of the polarizing plate is a cured product layer of the adhesive.

The active energy ray-curable adhesive may be an adhesive containing an epoxy compound cured by cationic polymerization as a curable component, and preferably an ultraviolet-curable adhesive containing the epoxy compound as a curable component. The epoxy compound is a compound having an average of 1 or more, preferably 2 or more epoxy groups in the molecule. The epoxy compound may be used in an amount of 1 or 2 or more.

Examples of the epoxy compound include hydrogenated epoxy compounds (glycidyl ethers of polyols having alicyclic rings) obtained by reacting epichlorohydrin with alicyclic polyols obtained by hydrogenation of aromatic rings of aromatic polyols; aliphatic epoxy compounds such as polyglycidyl ethers of aliphatic polyols and alkylene oxide adducts thereof; an alicyclic epoxy compound as an epoxy compound having 1 or more epoxy groups bonded to an alicyclic ring in the molecule.

The active energy ray-curable adhesive may contain a radically polymerizable (meth) acrylic compound as a curable component instead of the epoxy compound or together with the epoxy compound. The (meth) acrylic compound includes a (meth) acrylate monomer having 1 or more (meth) acryloyloxy groups in the molecule; (meth) acryloyloxy group-containing compounds such as (meth) acrylate oligomers having at least 2 (meth) acryloyloxy groups in the molecule, which are obtained by reacting 2 or more functional group-containing compounds.

When the active energy ray-curable adhesive contains an epoxy compound cured by cationic polymerization as a curable component, it preferably contains a photo-cationic polymerization initiator. Examples of the photo-cation polymerization initiator include aromatic diazonium salts; onium salts such as aromatic iodonium salts and aromatic sulfonium salts; iron-arene complexes, and the like.

When the active energy ray-curable adhesive contains a radical polymerizable component such as a (meth) acrylic compound, it preferably contains a photo radical polymerization initiator. Examples of the photo radical polymerization initiator include acetophenone-based initiators, benzophenone-based initiators, benzoin ether-based initiators, thioxanthone-based initiators, xanthone, fluorenone, camphorquinone, benzaldehyde, and anthraquinone.

The bonding of the polarizing plate 30 and the thermoplastic resin film may include a step of applying an adhesive composition to the bonding surface of the polarizing plate 30 and/or the bonding surface of the thermoplastic resin film, or a step of injecting an adhesive composition between the polarizing plate 30 and the thermoplastic resin film, and laminating the films of both by pressing them from above and below with a bonding roller or the like, for example, through a layer of the adhesive composition.

For forming the adhesive composition layer, various coating methods such as a blade, a wire bar, a die coater, a comma coater, a gravure coater, and the like can be used. The adhesive composition may be cast between the polarizer 30 and the thermoplastic resin film while continuously supplying them so that the bonding surface of the both is inside.

One or both of the bonding surfaces of the polarizing plate 30 and the thermoplastic resin film may be subjected to an easy-to-bond treatment (surface activation treatment) such as saponification treatment, corona discharge treatment, plasma treatment, flame treatment, primer treatment, anchor coating treatment, and the like before the adhesive composition is applied.

When an active energy ray-curable adhesive is used, an active energy ray is irradiated to cure the adhesive composition layer.

The light source for irradiation of the active energy ray may be any light source capable of generating ultraviolet rays, electron beams, X-rays, or the like. In particular, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, a chemical lamp, a black light lamp, a microwave-excited mercury lamp, a metal halide lamp, or the like having a light emission distribution at a wavelength of 400nm or less can be suitably used.

The thickness of the 1 st adhesive layer 15 and the 2 nd adhesive layer 25 in the polarizing plate is, for example, 0.1 μm or more and 100 μm or less, preferably 0.5 μm or more and 80 μm or less, more preferably 1 μm or more and 60 μm or less, and still more preferably 2 μm or more and 50 μm or less. From the viewpoint of thinning the polarizing plate, the thickness of the adhesive layer is preferably 30 μm or less, more preferably 20 μm or less. In the case of using the aqueous adhesive, the thickness of the adhesive layer may be smaller than the above thickness.

The thickness of the 1 st adhesive layer 15 and the 2 nd adhesive layer 25 may be the same or different.

[ 5 ] other constituent elements of the polarizing plate

5-1 optical functional film

The polarizing plate may be provided with an optical functional film other than the polarizing plate 30 for imparting a desired optical function, and a suitable example thereof is a retardation film.

As described above, the 2 nd thermoplastic resin film 20 may also serve as a retardation film, but a retardation film may be laminated in addition to the thermoplastic resin film. In the latter case, the retardation film may be laminated on the outer surface of the 2 nd thermoplastic resin film 20 via an adhesive layer or an adhesive layer. In addition, a retardation film may be laminated instead of the 2 nd thermoplastic resin film 20. In a specific example thereof, for example, in the configuration shown in fig. 1, in the single-sided protective polarizing plate in which the 1 st thermoplastic resin film 10 is bonded to one surface of the polarizing plate 30, a retardation film is bonded to the other surface of the polarizing plate 30. In this case, the retardation film may be laminated on the surface of the polarizing plate 30 via an adhesive layer or an adhesive layer.

The retardation film may be a birefringent film composed of a stretched film of a thermoplastic resin having light transmittance; a film in which discotic liquid crystals or nematic liquid crystals are oriented and fixed; the film of the liquid crystal layer is formed on the base film.

The base film is usually a film containing a thermoplastic resin, and one example of the thermoplastic resin is a cellulose ester resin such as triacetyl cellulose.

As the thermoplastic resin forming the birefringent film, the resin described for the 2 nd thermoplastic resin film 20 can be used.

Examples of other optically functional films (optical members) that may be included in the polarizing plate are a light condensing plate, a brightness enhancement film, a reflective layer (reflective film), a semi-transmissive reflective layer (semi-transmissive reflective film), a light diffusion layer (light diffusion film), and the like. These are generally provided in the case where the polarizing plate is a polarizing plate disposed on the back side (backlight side) of the liquid crystal cell.

5-2 adhesive layer

The polarizing plate of the present invention may include an adhesive layer for bonding the polarizing plate to an image display element such as a liquid crystal cell or an organic EL element, or to another optical member. The adhesive layer may be laminated on the outer surface (the surface opposite to the 1 st thermoplastic resin film 10 side) of the polarizing plate 30 in the polarizing plate having the configuration shown in fig. 1, and may be laminated on the outer surface of the 1 st thermoplastic resin film 10 or the 2 nd thermoplastic resin film 20 in the polarizing plate having the configuration shown in fig. 2.

In the polarizing plate according to a preferred embodiment, the adhesive layer is laminated on the outer surface of the 2 nd thermoplastic resin film 20, that is, on the surface opposite to the 1 st thermoplastic resin film 10 side with respect to the polarizing plate 30. In this embodiment, when the polarizing plate is bonded to the image display device, the polarizing plate is bonded to the image display device via the adhesive layer so that the 1 st thermoplastic resin film 10 side is the observation side.

As the adhesive used in the adhesive layer, an adhesive containing a (meth) acrylic resin, a silicone resin, a polyester resin, a polyurethane resin, a polyether resin, or the like as a base polymer can be used. Among them, the (meth) acrylic adhesive is preferable from the viewpoints of transparency, adhesion, reliability, weather resistance, heat resistance, reworkability, and the like.

The thickness of the pressure-sensitive adhesive layer is preferably in the range of 1 μm to 50 μm, more preferably 2 μm to 40 μm, depending on the adhesive strength and the like.

The polarizing plate may include a barrier film laminated on an outer surface of the adhesive layer. The separator may be a film containing polyethylene resin such as polyethylene, polypropylene resin such as polypropylene, polyester resin such as polyethylene terephthalate, or the like. Among them, a stretched film of polyethylene terephthalate is preferable.

The adhesive layer may contain glass fibers, glass beads, resin beads, fillers formed of metal powder, other inorganic powder, pigments, colorants, antioxidants, ultraviolet absorbers, antistatic agents, and the like as needed.

[ 5-3 ] protective film

The polarizing plate of the present invention may contain a protective film for protecting the surface thereof (thermoplastic resin film surface, polarizer surface, etc.). After the polarizing plate is attached to, for example, an image display element or other optical member, the protective film is peeled off together with the pressure-sensitive adhesive layer provided thereon.

In a preferred embodiment, a polarizing plate is laminated on the surface of the 1 st thermoplastic resin film 10 as the optical film of the present invention.

The protective film is composed of, for example, a base film and an adhesive layer laminated thereon. The above description can be cited with respect to the adhesive layer.

The resin constituting the base film may be, for example, a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, a polyester resin such as polyethylene terephthalate and polyethylene naphthalate, or a thermoplastic resin such as a polycarbonate resin. Polyester resins such as polyethylene terephthalate are preferable.

Examples

Hereinafter, the present invention will be described in further detail by way of examples, but the present invention is not limited to these examples. In the examples, the% and parts indicated in the content or the amount used are mass references unless otherwise indicated. The thickness of the film and the adhesive layer (cured layer) was measured using a digital micrometer "MH-15M" manufactured by Nikon corporation.

Example 1 ]

(1) Production of optical film I

The following raw materials were prepared.

(meth) acrylic resin (a): methacrylic resin (homopolymer of methyl methacrylate) having syndiotacticity (rr) of 76% represented by triad

(meth) acrylic resin (B-1): free radical copolymer with syndiotacticity (rr) of 48% expressed as triad of methyl methacrylate/methyl acrylate=97/3 (mass ratio)

Elastomer component (C): (meth) acrylic rubber particles as (meth) acrylic multilayer polymers comprising a three-layer structure (first layer (innermost layer): copolymer of methyl methacrylate and methyl acrylate and allyl methacrylate (mass ratio 93.8/6.0/0.2)/second layer: copolymer of butyl acrylate and styrene and allyl methacrylate (mass ratio 80.6/17.4/2.0)/third layer (outermost layer): copolymer of methyl acrylate and ethyl acrylate (mass ratio 94/6))

An unstretched resin film (resin layer) having a thickness of 50 μm was produced by melt extrusion from a mixture of 20 parts of (meth) acrylic resin (A), 55 parts of (meth) acrylic resin (B-1) and 25 parts of elastomer component (C).

The following components were dissolved in propylene glycol monomethyl ether to obtain an ultraviolet-curable resin composition. The resin solid content in the ultraviolet-curable resin composition was 50%.

60 parts of pentaerythritol triacrylate,

40 parts of multifunctional urethanized acrylate (reaction product of hexamethylene diisocyanate and pentaerythritol triacrylate)

The ultraviolet curable resin composition was mixed with 2.5 parts by weight of "Omnirad 184" (IGM Resins b.v. company) as a solid content and 1 part by weight of "Omnirad 819" (IGM Resins b.v. company) as a solid content per 100 parts by weight of the resin solid content, and then applied to one surface of the resin film by a bar coater, and dried at 80 ℃ for 3 minutes. The dried coating layer was run with "H tube" manufactured by Fusion company as a light source to accumulate 200mJ/cm of light ² An optical film I having a hard coat layer formed on the surface of the resin layer was produced by irradiating ultraviolet rays. The film thickness of the hard coat single film was 5. Mu.m.

(2) Manufacture of polarizing plate

The surface (the surface opposite to the hard coat layer) of the optical film I was subjected to corona treatment, and the curable adhesive composition a was applied to the corona treated surface by using an adhesive applicator. The obtained coated layer and a polyvinyl alcohol-iodine-based polarizing plate having a thickness of 23 μm were laminated using a nip roller to obtain a polarizing plate with an optical film I. In the polarizing plate with the optical film I, the mechanical flow direction (MD direction) of the optical film I is parallel to the absorption axis of the polarizing plate.

Then, the surface of a retardation film (trade name "ZEONOR" manufactured by ZEON corporation, japan) containing a cyclic polyolefin resin and having a thickness of 50 μm was subjected to corona treatment, and the curable adhesive composition B was applied to the corona-treated surface by using an adhesive applicator. The obtained coating layer and the polarizing plate surface of the polarizing plate with the optical film I were laminated using a nip roller to obtain a laminate. In the laminate, the mechanical flow direction (MD direction) of the retardation film is parallel to the absorption axis of the polarizing plate.

The total cumulative light amount of irradiation (cumulative light intensity in a wavelength region of 320 to 400 nm) from the retardation film side of the laminate was about 200mJ/cm ² Ultraviolet (UVB) light (measured by a measuring instrument, UV Power PuckII, fusionUV Co., ltd.) cures the layer of the curable adhesive composition B and the layer of the curable adhesive composition A to produce a polarizing plate. The thickness of the cured layer of the curable adhesive composition a was about 3 μm, and the thickness of the cured layer of the curable adhesive composition B was about 3 μm.

The curable adhesive composition A was prepared by mixing 20 parts of 3, 4-epoxycyclohexane carboxylic acid 3',4' -epoxycyclohexyl methyl ester (trade name "Celloxide 2021P" manufactured by Daicel Co., ltd.) 70 parts of neopentyl glycol diglycidyl ether (trade name "EX-211L" manufactured by Nagase ChemteX Co., ltd.), 2 parts of 4-hydroxybutyl vinyl ether (trade name "HBVE" manufactured by Japanese Carbide), 8 parts of methyl methacrylate-glycidyl methacrylate copolymer (cationic polymerizable polymer) (trade name "Marproof G-01100" manufactured by daily oil Co., ltd.) and 2.25 parts of a photopolymerization initiator (trade name "CPI-100P" manufactured by San-Apro Co., ltd.) and defoaming the mixture.

The curable adhesive composition B was prepared by mixing 25 parts of 1, 4-butanediol diglycidyl ether (trade name "EX-214L" manufactured by Nagase ChemteX Co., ltd.) and 2.8 parts of a photopolymerization initiator (trade name "CPI-100P" manufactured by San-Apro Co., ltd.) with 100 parts of 3, 4-epoxycyclohexylmethyl 3',4' -epoxycyclohexane carboxylate (trade name "Celloxide2021P" manufactured by Daicel Co., ltd.) and defoaming the mixture.

Example 2 ]

(1) Production of optical film II

An unstretched resin film (resin layer) having a thickness of 50 μm was produced by melt extrusion from a mixture of 21 parts of (meth) acrylic resin (A), 59 parts of (meth) acrylic resin (B-1) and 20 parts of elastomer component (C). The same materials as in example 1 were used as the (meth) acrylic resin (a), (meth) acrylic resin (B-1) and the elastomer component (C). An optical film II was produced by forming a hard coat layer in the same manner as in example 1, except that the resin film was used.

(2) Manufacture of polarizing plate

A polarizing plate was produced in the same manner as in example 1, except that the optical film II was used instead of the optical film I.

Comparative example 1 ]

(1) Fabrication of optical film III

An unstretched resin film (resin layer) having a thickness of 50 μm was produced from a mixture of 75 parts of (meth) acrylic resin (A) and 25 parts of elastomer component (C) by melt extrusion. The same materials as in example 1 were used as the (meth) acrylic resin (a) and the elastomer component (C). An optical film III was produced by forming a hard coat layer in the same manner as in example 1, except that the resin film was used.

(2) Manufacture of polarizing plate

A polarizing plate was produced in the same manner as in example 1, except that the optical film III was used instead of the optical film I.

Example 3 ]

(1) Fabrication of optical film IV

The following raw materials were prepared.

(meth) acrylic resin (B-2): a radical copolymer having a syndiotacticity (rr) of 51% expressed as a triad of methyl methacrylate/methyl acrylate=98.6/1.4 (mass ratio)

An unstretched resin film (resin layer) having a thickness of 60 μm was produced by melt extrusion from a mixture of 12 parts of (meth) acrylic resin (A), 68 parts of (meth) acrylic resin (B-2) and 20 parts of elastomer component (C). The same materials as in example 1 were used as the (meth) acrylic resin (a) and the elastomer component (C). An optical film IV was produced by forming a hard coat layer in the same manner as in example 1, except that the resin film was used.

(2) Manufacture of polarizing plate

A polarizing plate was produced in the same manner as in example 1, except that the optical film IV was used instead of the optical film I.

Example 4 ]

(1) Production of optical film V

An unstretched resin film (resin layer) having a thickness of 60 μm was produced from a mixture of 7.5 parts of (meth) acrylic resin (A), 67.5 parts of (meth) acrylic resin (B-2) and 25 parts of elastomer component (C) by melt extrusion. The same materials as in example 1 were used as the (meth) acrylic resin (a) and the elastomer component (C). An optical film V was produced by forming a hard coat layer in the same manner as in example 1, except that the resin film was used.

(2) Manufacture of polarizing plate

A polarizing plate was produced in the same manner as in example 1, except that the optical film V was used instead of the optical film I.

Example 5 ]

(1) Fabrication of optical film VI

An unstretched resin film (resin layer) having a thickness of 60 μm was produced from a mixture of 22.5 parts of (meth) acrylic resin (A), 52.5 parts of (meth) acrylic resin (B-2) and 25 parts of elastomer component (C) by melt extrusion. The same materials as in example 1 were used as the (meth) acrylic resin (a) and the elastomer component (C). An optical film VI was produced by forming a hard coat layer in the same manner as in example 1, except that the resin film was used.

(2) Manufacture of polarizing plate

A polarizing plate was produced in the same manner as in example 1, except that the optical film VI was used instead of the optical film I.

Example 6 ]

(1) Preparation of optical film VII

An unstretched resin film (resin layer) having a thickness of 60 μm was produced by melt extrusion from a mixture of 14 parts of (meth) acrylic resin (A), 56 parts of (meth) acrylic resin (B-2) and 30 parts of elastomer component (C). The same materials as in example 1 were used as the (meth) acrylic resin (a) and the elastomer component (C). An optical film VII was produced in the same manner as in example 1, except that the resin film was used.

(2) Manufacture of polarizing plate

A polarizing plate was produced in the same manner as in example 1, except that the optical film VII was used instead of the optical film I.

< measurement and evaluation >

(1) Determination of tensile elastic modulus of optical film

(1-1) measurement of tensile elastic modulus in MD at 23 ℃

Rectangular test pieces having a length of 100mm by a width of 10mm were cut out from the optical films obtained above. The longitudinal direction of the test piece was parallel to the MD direction of the optical film and to the absorption axis of the polarizing plate included in the produced polarizing plate. The width direction of the test piece was parallel to the TD direction (direction orthogonal to the MD direction) of the optical film and orthogonal to the absorption axis of the polarizing plate included in the produced polarizing plate. Then, both ends of the test piece in the longitudinal direction (MD direction of the optical film) were held by upper and lower clamps of a tensile tester (Autograph AG-1S tester manufactured by Shimadzu corporation) so that the interval between the clamps was 5cm, and the test piece was pulled in the longitudinal direction (MD direction of the optical film) at a pulling rate of 50 mm/min at 23℃under an environment, and the elastic modulus (tensile elastic modulus) [ MPa ] in the MD direction of the optical film at 23℃was calculated from the slope of the initial straight line of the obtained stress-strain curve.

(1-2) measurement of tensile elastic modulus in TD at 23 ℃ in the TD direction

Rectangular test pieces having a length of 100mm by a width of 10mm were cut out from the optical films obtained above. The longitudinal direction of the test piece was parallel to the TD direction of the optical film and perpendicular to the absorption axis of the polarizing plate included in the produced polarizing plate. The width direction of the test piece was parallel to the MD direction of the optical film and to the absorption axis of the polarizing plate included in the produced polarizing plate. Then, both ends of the test piece in the longitudinal direction (the TD direction of the optical film) were held by upper and lower clamps of a tensile tester (Autograph AG-1S tester manufactured by shimadzu corporation) so that the interval between the clamps was 5cm, and the test piece was pulled in the longitudinal direction (the TD direction of the optical film) at a pulling rate of 50 mm/min at a temperature of 23 ℃.

(1-3) measurement of tensile elastic modulus at 80 ℃

The tensile elastic modulus in the MD direction at 80℃and the tensile elastic modulus in the TD direction at 80℃were measured in the same manner as in (1-1) and (1-2) above, except that the measurement was performed in an environment of 80 ℃.

The tensile elastic modulus in the MD direction at each temperature is shown in column "MD" of Table 1, and the tensile elastic modulus in the TD direction is shown in column "TD" of Table 1. The tensile elastic modulus in the TD direction was divided by the tensile elastic modulus in the MD direction, and the obtained values are shown in the column "TD/MD" in Table 1.

(2) Determination of Charpy impact Strength of optical films

Rectangular test pieces having a length of 100mm by a width of 10mm were cut out from the optical films obtained above. Using the obtained test piece, a Charpy impact test was performed in an environment of a temperature of 23℃and a relative humidity of 50% RH using a pendulum 1J (rotational moment: 0.540116 N.multidot.m) in accordance with ISO179-1 and JIS K7111-1. For absorption energy (kJ/m) ² ) 10 determinations were made and the average value thereof was used. The results are shown in Table 1.

(3) Determination of pencil hardness of optical film

The scratch hardness was measured according to JIS K5600-5-4 using a No553-M1 electric pencil scratch hardness tester manufactured by a An Tian refiner. First, an optical film was fixed on a glass plate with an adhesive tape so that the hard coat layer faced up, a pencil was placed so as to reach 45 degrees, a load of 500g was applied, and the surface of the sample (hard coat layer surface) was scratched. 5 trials were performed using pencils of the same hardness. The pencil hardness was changed to F to 2H, and the same scratch test was performed. The film with the scratched surface was placed on a blackboard, and the presence or absence of flaws on the surface of the film was observed by reflection using a fluorescent lamp. The maximum pencil hardness, which was found to be free from scratch, among 5 times, was taken as the pencil hardness of the film. The results are shown in Table 1.

(4) Evaluation of adhesion

(4-1) initial adhesion

An adhesive layer was formed on the optical film side (the side opposite to the retardation film) of the obtained polarizing plate. The obtained polarizing plate with the adhesive layer was cut into a size of 200mm in length (parallel to the absorption axis direction of the polarizing plate) and 25mm in width, and the adhesive layer was bonded to a glass plate to obtain a laminate. The mixture was left to stand at a temperature of 23℃and a relative humidity of 50% RH for 24 hours. Thereafter, a cutter blade of a dicing blade was inserted between the polarizing plate and the optical film of the obtained laminate, the laminate was peeled off from the end portion by 30mm in the longitudinal direction, the peeled portion was held by a jig portion of a tester, and the glass plate was held by a lower portion of the jig. The test piece in this state was subjected to a temperature of 23℃and a relative humidity of 55% in an atmosphere in accordance with JIS K6854-2:1999 "adhesive-peel adhesion Strength test method-part 2: 180 degree peeling ", peeling test was performed at a jig moving speed of 300 mm/min, and an average peeling force (unit: N/25 mm) of 60mm length excluding 30mm of the jig portion was obtained as peeling strength between the polarizing plate and the optical film. The results are shown in Table 1.

(4-2) adhesion after exposure to high-temperature and high-humidity Environment

An adhesive layer was formed on the optical film side (the side opposite to the retardation film) of the obtained polarizing plate. The obtained polarizing plate with the adhesive layer was cut into a size of 200mm in length (parallel to the absorption axis direction of the polarizing plate) and 25mm in width, and the adhesive layer was bonded to a glass plate to obtain a laminate. The laminate obtained was left to stand in a high-temperature and high-humidity environment at a temperature of 80℃and a relative humidity of 90% RH for 24 hours, and then left to stand in an environment at a temperature of 23℃and a relative humidity of 50% RH for 24 hours. Thereafter, a cutter blade of a dicing blade was inserted between the polarizing plate and the optical film of the obtained laminate, the laminate was peeled off from the end portion by 30mm in the longitudinal direction, the peeled portion was held by a jig portion of a tester, and the glass plate was held by a lower portion of the jig. The test piece in this state was subjected to a temperature of 23℃and a relative humidity of 55% in an atmosphere in accordance with JIS K6854-2: 1999 "adhesive-peel adhesion Strength test method-part 2: 180 degree peeling ", peeling test was performed at a jig moving speed of 300 mm/min, and an average peeling force (unit: N/25 mm) of 60mm length excluding 30mm of the jig portion was obtained as peeling strength between the polarizing plate and the optical film. The results are shown in Table 1.

TABLE 1

Description of the reference numerals

10 st thermoplastic resin film, 15 st adhesive layer, 20 nd thermoplastic resin film, 25 nd adhesive layer, 30 polarizing plate.

Claims (6)

1. An optical film comprising a resin layer containing a (meth) acrylic resin A, a (meth) acrylic resin B and an elastomer component C,

the (meth) acrylic resin A has a higher syndiotacticity than the (meth) acrylic resin B,

when the content of the (meth) acrylic resin a in the resin layer is a and the content of the elastomer component C is C, the resin layer satisfies the following formula [1]:

A/(A+C) <0.6 [1]

The units of A, C are parts by mass.

2. The optical film according to claim 1, wherein,

when the content of the (meth) acrylic resin B in the resin layer is B, the following formula [2] is further satisfied:

A/(A+B) is more than or equal to 0.05 and less than or equal to 0.4 formula [2]

The unit of the B is mass parts.

3. The optical film according to claim 1 or 2, wherein,

the elastomer component C is rubber particles.

4. The optical film according to any one of claims 1 to 3, further comprising a surface treatment layer laminated on the resin layer.

5. The optical film according to any one of claims 1 to 4, which is a protective film for a polarizing plate.

6. A polarizing plate comprising, in order, a polarizing plate, an adhesive layer, and the optical film according to any one of claims 1 to 5.