KR20230148188A - Optical films and polarizers - Google Patents

Abstract

(Problem) To provide a (meth)acrylic resin-based optical film that can improve adhesion to a polarizer when placed in a high temperature and high humidity environment.
(Solution) A resin layer containing a (meth)acrylic resin (A), a (meth)acrylic resin (B), and an elastomer component (C) is provided, and the (meth)acrylic resin (A) has syndiotacticity. It is higher than the (meth)acrylic resin (B), and 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 An optical film satisfying /(A+C)<0.6 is provided.

Description

Optical films and polarizers

The present invention relates to optical films and polarizers.

Polarizing plates, which are widely used in image display devices such as liquid crystal display devices and organic EL display devices, usually have a structure in which a thermoplastic resin film is bonded as a protective film to one or both sides of the polarizer. Japanese Patent Application Laid-Open No. 2008-102274 (Patent Document 1) describes that an acrylic resin film can be used as a protective film.

Patent Document 1: Japanese Patent Publication No. 2008-102274

The polarizing plate using a (meth)acrylic resin film as a protective film had room for improvement in the adhesion between the polarizer and the (meth)acrylic resin film when placed in a high temperature and high humidity environment.

The purpose of the present invention is to provide a (meth)acrylic resin-based optical film capable of improving the above-described adhesion.

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

[1] An optical film comprising a resin layer containing (meth)acrylic resin (A), (meth)acrylic resin (B), and 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 has the following formula [1 ]:

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

Optical film that meets the requirements.

[2] When the content of the (meth)acrylic resin (B) in the resin layer is B (parts by mass), the following formula [2]:

0.05≤A/(A+B)≤0.4 Equation [2]

The optical film according to [1], which further satisfies the following.

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

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

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

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

A (meth)acrylic resin-based optical film capable of improving adhesion to a polarizer when placed in a high-temperature, high-humidity environment can be provided.

1 is a schematic cross-sectional view showing an example of the layer structure of a polarizing plate according to the present invention.
Figure 2 is a schematic cross-sectional view showing another example of the layer structure of a polarizing plate according to the present invention.

<Optical film>

The optical film (hereinafter also referred to as “optical film”) according to the present invention has a resin layer containing (meth)acrylic resin (A), (meth)acrylic resin (B), and elastomer component (C). It is a film provided and can be suitably used as a protective film for polarizers.

Hereinafter, the (meth)acrylic resin (A), (meth)acrylic resin (B), and elastomer component (C) are also referred to as “component (A),” “component (B),” and “component (C),” respectively.

Component (A) and component (B) have at least different syndiotacticities, and specifically, component (A) has higher syndiotacticity than component (B).

In this specification, “(meth)acrylic” represents at least one type selected from the group consisting of acrylic and methacryl. The same applies to expressions such as “(meth)acryloyl” and “(meth)acrylate.”

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

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

satisfies.

The optical film according to the present invention can have good adhesion to the polarizer when adhered to the polarizer using an adhesive, and thereby the durability of the polarizing plate can be improved. In particular, the optical film according to the present invention can have good adhesion to the polarizer when adhered to the polarizer using an adhesive even when exposed to a high temperature and high humidity environment, thereby providing good durability of the polarizer in a high temperature and high humidity environment. It can be done with

[1] Composition of optical film

The optical film may be a single-layer film, that is, it may be composed of the above resin layer. Alternatively, the optical film may contain layers other than the resin layer, and an 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, and still more preferably 15 μm or more and 65 μm or less. The thickness of the resin layer may be 60 μm or less, and may be 50 μm or less. Reducing the thickness of the resin layer is advantageous for reducing the thickness of the polarizing plate and, by extension, the image display device to which it is applied.

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

However, from the viewpoint of heat resistance and toughness of the optical film, it is preferable that the total content of component (A) and component (B) in the resin component (component (C) is not included) contained in the resin layer is high, and The total content is preferably 80% by mass or more, more preferably 90% by mass or more, and even more preferably 95% by mass or more.

Component (A) is preferably a polymer containing methacrylic acid ester as the main monomer (containing 50% by mass or more). Component (A) may be a homopolymer of methacrylic acid ester, or may be a copolymer of methacrylic acid ester and another copolymerization component.

Component (A) has a content of structural units derived from methacrylic acid ester, preferably 90% by mass or more, more preferably 95% by mass or more, further preferably 98% by mass or more, even more preferably It is 99% by mass or more, particularly preferably 100% by mass.

In one preferred embodiment, component (A) is a homopolymer of methacrylic acid ester. In another preferred embodiment, component (A) is a homopolymer of methyl methacrylate.

The methacrylic acid esters include, for example, methyl methacrylate, ethyl methacrylate, n-, i-, or t-butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, and metacrylate. Examples include 2-ethylhexyl acrylate and 2-hydroxyethyl methacrylate. Component (A) may contain structural units derived from one type or two or more types of methacrylic acid ester.

Methacrylic acid ester preferably contains methyl methacrylate, and more preferably is methyl methacrylate.

Other copolymerization components include, for example,

Acrylic acid esters such as ethyl acrylate, n-, i- or t-butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate;

2-(hydroxymethyl)methyl acrylate, 2-(1-hydroxyethyl)methyl acrylate, 2-(hydroxymethyl)ethyl acrylate, n-, i- or t-butyl 2-(hydroxymethyl)acrylate, etc. hydroxyalkyl acrylic acid esters;

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 acid anhydrides such as maleic anhydride and citraconic anhydride;

Unsaturated imides such as phenylmaleimide and cyclohexylmaleimide;

Monofunctional monomers such as these can be mentioned.

As for the other monofunctional monomers mentioned above, only one type may be used individually, or two or more types may be used in combination.

A polyfunctional monomer may be used as the other copolymerization component.

Multifunctional monomers include, for example, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, and nonaethylene glycol. Di(meth)acrylate, tetradecaethylene glycol di(meth)acrylate, etc. obtained by esterifying both terminal hydroxyl groups of ethylene glycol or its oligomer with (meth)acrylic acid;

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

Products obtained by esterifying the hydroxyl group of a dihydric alcohol such as neopentyl glycol di(meth)acrylate, hexanediol di(meth)acrylate, and butanediol di(meth)acrylate with (meth)acrylic acid;

Bisphenol A, alkylene oxide adducts of bisphenol A, or halogen-substituted products thereof obtained by esterifying both terminal hydroxyl groups with (meth)acrylic acid;

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

ring-opening addition of the epoxy group of glycidyl (meth)acrylate to dibasic acids such as succinic acid, adipic acid, terephthalic acid, phthalic acid, halogen-substituted products thereof, or alkylene oxide adducts thereof;

Aryl (meth)acrylate; Aromatic divinyl compounds such as divinylbenzene;

etc. can be mentioned.

The weight average molecular weight Mw of component (A) is, for example, 40,000 or more and 150,000 or less, and is preferably 40,000 or more and 120,000 or less, and more preferably 50,000 from the viewpoint of heat resistance of the optical film, adhesion to a polarizer, and moldability into a film. More than 100000 or less.

The molecular weight distribution (weight average molecular weight Mw/number average molecular weight Mn) of component (A) is, for example, 1.01 or more and 1.8 or less, and is preferably 1.03 or more and 1.5 or less from the viewpoint of heat resistance of the optical film and adhesion to the polarizer. Preferably it is 1.05 or more and 1.3 or less.

Mw and Mn can be controlled by adjusting the type and/or amount of the polymerization initiator used when preparing component (A). Mw and Mn are measured by gel permeation chromatography (GPC) (standard polystyrene conversion).

From the viewpoint of increasing the toughness of the optical film, the glass transition temperature Tg of component (A) is preferably 110°C or higher and 160°C or lower, more preferably 120°C or higher and 150°C or lower, and even more preferably 125°C or higher. It is below 140℃. Tg can be controlled by adjusting molecular weight, syndiotacticity, etc.

The syndiotacticity (rr) in the three-character designation of component (A) is, for example, 55% or more, and is preferably 60% or more from the viewpoint of increasing the toughness of the optical film and the heat resistance of the optical film. Preferably it is 65% or more, and more preferably 70% or more. The syndiotacticity (rr) of component (A) in the three-character display is usually 90% or less, and may be 85% or less.

Syndiotacticity (rr), expressed in triple letters, is the ratio of two chains (diads, diads) of a chain (triads, triads) of three consecutive structural units being racemose (notated as rr). am. Syndiotacticity (rr) (%) in three-letter display is obtained by measuring ^{the 1} H-NMR spectrum at 30°C in CDCL ₃ , and from the spectrum, it is 0.6 to 0.95 ppm when the internal standard TMS is set to 0 ppm. The area (X) of the region and the area (Y) of the region of 0.6 to 1.35 ppm are measured, and calculated as (X/Y) x 100.

Component (A) having a syndiotacticity (rr) in the above range in 3-letter form can be prepared, for example, according to the method described in International Publication No. 2016/080124, by lowering the temperature during polymerization or polymerization. By lengthening the time, the ratio of syndiotacticity (rr) of the three-character display can be increased.

Component (B) may be, for example, a polymer (containing 50 mass% or more) containing methacrylic acid ester as the main monomer, and is preferably a copolymer in which methacrylic acid ester and other copolymerization components are copolymerized. In one preferred embodiment, component (B) is a copolymer containing a structural unit derived from methyl methacrylate. In another preferred embodiment, component (B) is a copolymer containing a structural unit derived from methyl methacrylate and a structural unit derived from methyl acrylate.

Examples of other copolymerization components other than methyl acrylate include those exemplified as methacrylic acid ester and other copolymerization components for component (A).

The weight average molecular weight Mw of component (B) is, for example, 40,000 or more and 150,000 or less, and is preferably 40,000 or more and 130,000 or less, and more preferably 50,000 from the viewpoint of heat resistance of the optical film, adhesion to the polarizer, and moldability into a film. More than 120000 or less.

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

Mw and Mn can be controlled by adjusting the type and/or amount of the polymerization initiator used when preparing component (B). Mw and Mn are measured by gel permeation chromatography (GPC) (standard polystyrene conversion).

The glass transition temperature Tg of component (B) is preferably 80°C or higher and 140°C or lower, more preferably 90°C or higher and 130°C or lower, and even more preferably 90°C or higher and 125°C or lower. Tg can be controlled by adjusting molecular weight, syndiotacticity, etc.

The syndiotacticity (rr) of the three-character display of component (B) is lower than that of component (A). The syndiotacticity (rr) of the component (B) in three-character terms 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%.

Component (B) can be prepared by referring to the method described in, for example, Japanese Patent Application Laid-Open No. 2009-145397 or Japanese Patent Application Laid-Open No. 2021-155698. Component (B) may be prepared by radical polymerization.

The resin layer contains component (C). Containing component (C) is advantageous in improving the toughness of the optical film and the adhesion to the polarizer. Component (C) includes rubber particles.

Rubber particles are rubber elastomer particles containing a layer exhibiting rubber elasticity. The rubber particles may be particles composed only of a layer exhibiting rubber elasticity, or may be particles of a multilayer structure having other layers along with the layer exhibiting rubber elasticity. Examples of the rubber elastomer include olefin-based elastomer, diene-based elastomer, styrene-diene-based elastomer copolymer, and acrylic elastomer. Among them, acrylic elastic polymer is preferably used from the viewpoint of light resistance and transparency of the optical film.

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

The alkyl acrylate constituting the acrylic elastic polymer is usually one whose alkyl group has 4 to 8 carbon atoms.

Examples of the other polymerizable monomers include alkyl methacrylates such as methyl methacrylate and ethyl methacrylate; Styrene-based monomers such as styrene and alkyl styrene; monofunctional monomers such as unsaturated nitriles such as acrylonitrile and methacrylonitrile, and further alkenyl esters of unsaturated carboxylic acids such as allyl (meth)acrylate and metharyl (meth)acrylate; Dialkenyl esters of dibasic acids such as diallyl maleate; and 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 with a multilayer structure having a layer of the acrylic elastic polymer. Specifically, it has a two-layer structure with a hard polymer layer mainly composed of alkyl methacrylate on the outside of the acrylic elastomer layer, and a hard polymer layer mainly composed of alkyl methacrylate on the inside of the acrylic elastomer layer. A three-layer structure having a polymer layer of: Alkyl methacrylate is preferably methyl methacrylate.

It is preferable that the average particle diameter of the rubber particles up to the rubber elastomer layer (acrylic elastomer layer) included therein is in the range of 10 nm to 350 nm. The average particle size in this range is advantageous in improving the toughness of the optical film and the adhesion to the polarizer. The average particle diameter is more preferably 30 nm or more, further preferably 50 nm or more, and further preferably 320 nm or less, further preferably 300 nm or less.

The average particle diameter from the rubber particles to the rubber elastomer layer (layer of acrylic elastomer) can be measured as follows. That is, when these rubber particles are mixed with (meth)acrylic resin to form a film and the cross section is stained with an aqueous solution of ruthenium oxide, only the rubber elastomer layer is colored and observed to be almost circular, and the (meth)acrylic resin of the parent layer is dyed. It doesn't work. Therefore, from the cross section of the film dyed in this way, a thin section is prepared using a microtome or the like, and this is observed with an electron microscope. Then, 100 dyed rubber particles are randomly extracted, the diameter of each particle (diameter to the rubber elastomer layer) is calculated, and the number average value is taken as the average particle diameter. By measuring in this way, the average particle size obtained becomes the number average particle size.

If the outermost layer is a hard polymer mainly composed of methyl methacrylate and is a rubber particle enclosing a rubber elastomer layer (layer of acrylic elastomer) within it, mixing it with the base (meth)acrylic resin creates a rubbery rubber. The outermost layer of the particle is mixed with the base (meth)acrylic resin. Therefore, when the cross section is stained with ruthenium oxide and observed with an electron microscope, the rubber particles are observed as particles with the outermost layer removed. Specifically, in the case of a rubber particle with a two-layer structure in which the inner layer is an acrylic elastomer and the outer layer is a hard polymer mainly composed of methyl methacrylate, the acrylic elastomer portion of the inner layer is dyed and observed as a single-layer structured particle. do. In addition, in the case of rubber particles with a three-layer structure in which the innermost layer is a hard polymer mainly composed of methyl methacrylate, the middle layer is an acrylic elastomer, and the outermost layer is a hard polymer mainly composed of methyl methacrylate, The particle center portion of the innermost layer is not dyed, and only the acrylic elastomer portion of the middle layer is dyed, which is observed as a particle with a two-layer structure.

The resin layer satisfies the above equation [1]. As a result, the optical film can have good adhesion to the polarizer when adhered to the polarizer using an adhesive, and in particular, even when exposed to a high temperature and high humidity environment, the optical film has good adhesion to the polarizer when adhered to the polarizer using the adhesive. Adhesion can be improved. A/(A+C) may be 0.55 or less, 0.50 or less, 0.45 or less, and 0.40 or less.

A/(A+C) is preferably 0.1 or more, more preferably 0.2 or more, from the viewpoint of adhesion.

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

The resin layer has the following formula [2]:

0.05≤A/(A+B)≤0.4 Equation [2]

It is desirable to further satisfy. Satisfying the formula [2] is advantageous in improving the toughness of the optical film and the adhesion to the polarizer.

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

The content of component (A) in the resin layer is preferably 1 mass% or more and 50 mass% or less, more preferably 5 mass% or more and 40 mass% or less from the viewpoint of the toughness of the optical film and the adhesion to the polarizer. , more preferably 10 mass% or more and 35 mass% or less, and even more preferably 15 mass% or more and 30 mass% or less.

The content of 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, from the viewpoint of the toughness of the optical film and adhesion to the polarizer. , more preferably 30 mass% or more and 80 mass% or less, and even more preferably 40 mass% or more and 70 mass% or less.

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

The resin layer may contain components other than the above as needed. Other components include, for example, lubricants, anti-blocking agents, heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, impact resistance improvers, surfactants, mold release agents, etc.

The resin layer has the following formula [3], when the tensile modulus of elasticity in the MD direction at 23°C is E23(MD) and the tensile modulus of elasticity in the TD direction at 23°C is E23(TD):

0.5≤E23(TD)/E23(MD)≤1.5 Equation [3]

It is desirable to satisfy. E23(TD)/E23(MD) in formula [3] may be 0.6 or more and 1.4 or less, may be 0.7 or more and 1.3 or less, may be 0.8 or more and 1.3 or less, may be 0.9 or more and 1.3 or less, and may be 0.9 or more and 1.2 or less. , it may be 0.9 or more and 1.1 or less. The units for E23(MD) and E23(TD) are MPa.

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

The resin layer has the following formula [4] when the tensile elastic modulus in the MD direction at 80°C is E80(MD) and the tensile elastic modulus in the TD direction at 80°C is E80(TD):

0.5≤E80(TD)/E80(MD)≤1.5 Equation [4]

It is desirable to satisfy. E80(TD)/E80(MD) in formula [4] may be 0.6 or more and 1.4 or less, may be 0.7 or more and 1.3 or less, may be 0.8 or more and 1.3 or less, may be 0.9 or more and 1.3 or less, and may be 0.9 or more and 1.2 or less. , it may be 0.9 or more and 1.1 or less. The units for E80(MD) and E80(TD) are MPa.

The resin layer has an absorbed energy (Charpy impact strength) measured by a Charpy impact test of preferably 140 kJ/m2 or more, more preferably 160 kJ/m2 or more, and even more preferably 170 kJ/m2 or more. , and even more preferably 180 kJ/m2 or more, and particularly preferably 200 kJ/m2 or more. The Charpy impact strength is usually 350 kJ/m2 or less, and may be 300 kJ/m2 or less. The Charpy impact test is conducted in an environment with a temperature of 23°C and a relative humidity of 50% RH.

Setting the Charpy impact strength within the above range is advantageous in improving the adhesion between the polarizer and the optical film, especially when placed in a high temperature and high humidity environment.

The tensile elastic modulus and Charpy impact strength of the resin layer can be measured by the method described in the [Examples] section described later.

[3] Surface treatment layer

Examples of the surface treatment layer include a hard coat layer, an anti-glare layer, an anti-reflection layer, a light diffusion layer, an anti-static layer, an anti-pollution layer, and a conductive layer, and the hard coat layer is preferable. In addition, the surface treatment layer may have multiple functions as a single layer, and may be, for example, a layer having hard coat properties and anti-glare properties. A surface treatment layer (coating layer) is laminated on the resin layer, and is usually laminated directly on the resin layer. The surface of the resin layer on which the surface treatment layer is laminated is usually the surface on the opposite side to the polarizer side in a polarizing plate formed by bonding an optical film to a polarizer.

Examples of the surface treatment layer include a cured product layer of a curable resin composition containing an active energy ray-curable compound. An active energy ray-curable compound is a compound that polymerizes and hardens by irradiation of active energy rays such as ultraviolet rays or electron beams.

Examples of active energy ray-curable compounds include mono-, di-, or tri- or more functional (meth)acrylate compounds. The active energy ray-curable compound can be used one type or two or more types.

Monofunctional (meth)acrylate compounds include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and ethyl (meth)acrylate. Latex, 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, stearyl (meth)acrylate, benzyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, 3-methoxybutyl (meth)acrylate Rate, 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, nonylphenol (meth)acrylate, ethylene oxide modified nonylphenol (meth)acrylate, propylene oxide modified nonylphenol (meth)acrylate, methoxydiethylene glycol (meth)acrylate, methoxy Polytylene glycol (meth)acrylate, methoxypropylene glycol (meth)acrylate, 2-(meth)acryloyloxyethyl-2-hydroxypropyl phthalate, 2-hydroxy-3-phenoxypropyl (meth) Acrylate, 2-(meth)acryloyloxyethylhydrogenphthalate, 2-(meth)acryloyloxypropylhydrogenphthalate, 2-(meth)acryloyloxypropylhexahydrohydrogenphthalate, 2-( Meth)acryloyloxypropyltetrahydrogen phthalate, dimethylaminoethyl (meth)acrylate, trifluoroethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, hexafluoropropyl (meth)acrylate ester, octafluoropropyl (meth)acrylate, octafluoropropyl (meth)acrylate, adamantane derivative mono(meth)acrylate (e.g., monovalent mono(meth)acrylate derived from adamantanediol) and adamantyl acrylate).

Bifunctional (meth)acrylate compounds include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, butanediol di(meth)acrylate, hexanediol di(meth)acrylate, and nonanedi. Old di(meth)acrylate, ethoxylated hexanediol di(meth)acrylate, propoxylated hexanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, di Propylene 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, isoboronyl di(meth)acrylate ) Di(meth)acrylates such as acrylate, dicyclopentane di(meth)acrylate, and tricyclodecane di(meth)acrylate.

Examples of trifunctional or higher (meth)acrylate compounds include trimethylolpropane tri(meth)acrylate, ethoxylated trimethylolpropane tri(meth)acrylate, propoxylated trimethylolpropane tri(meth)acrylate, and tris 2- Hydroxyethyl isocyanurate tri(meth)acrylate, glycerin tri(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol tri(meth)acrylate, ditrimethylolpropane tri(meth) ) Acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, ditrimethylol Propane tetra(meth)acrylate, ditrimethylolpropane penta(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ditrimethylolpropane hexa(meth)acrylate In addition to latex, tripentaerythritol octa(meth)acrylate, and tetrapentaerythritol deca(meth)acrylate, polyfunctional (meth)acrylates in which some of these (meth)acrylates are replaced with alkyl groups or ε-caprolactone. Late compounds, etc. can be mentioned.

Other examples of active energy ray-curable compounds include oligomers or polymers such as urethane (meth)acrylate, isocyanurate (meth)acrylate, polyester-urethane (meth)acrylate, and epoxy (meth)acrylate. You can.

Urethane (meth)acrylates include pentaerythritol triacrylate hexamethylene diisocyanate urethane prepolymer, dipentaerythritol pentaacrylate hexamethylene diisocyanate urethane prepolymer, pentaerythritol triacrylate toluene diisocyanate urethane prepolymer, and dipentaerythritol triacrylate toluene diisocyanate urethane prepolymer. Erythritol pentaacrylate toluene diisocyanate urethane prepolymer, pentaerythritol triacrylate isophorone diisocyanate urethane prepolymer, and dipentaerythritol pentaacrylate isophorone diisocyanate urethane prepolymer.

The curable resin composition may further include a thermoplastic resin. Thermoplastic resins include, for example, styrene-based resins, (meth)acrylic-based resins, vinyl acetate-based resins, vinyl ether-based resins, halogen-containing resins, alicyclic olefin-based resins, polycarbonate-based resins, polyester-based resins, and polyamide-based resins. Resins, cellulose derivatives, silicone resins, rubbers or elastomers, etc. can be mentioned.

The curable resin composition may further include a thermosetting resin. Thermosetting resins include, for example, phenol resin, urea resin, diallyl phthalate resin, melamine resin, guanamine resin, unsaturated polyester resin, polyurethane resin, epoxy resin, aminoalkyd resin, melamine-urea cocondensation resin, and silicon resin. , polysiloxane resin, etc.

The curable resin composition may contain one type or two or more types of radical photopolymerization initiators. Examples of radical photopolymerization initiators include acetophenones, benzophenones, Michler benzoylbenzoate, α-amyloxime ester, thioxanthone, propiophenone, benzyl, benzoin, and acylphosphine oxide. . The curable resin composition may further contain one or two or more types of photosensitizer. Examples of photosensitizers 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 are fine particles made of at least one material selected from the group consisting of acrylic resin, polystyrene resin, styrene-acrylic copolymer, polyethylene resin, epoxy resin, silicone resin, polyvinylidene fluoride resin, and polyethylene fluoride resin. I can hear it. Inorganic fine particles include silica (SiO ₂ ) fine particles, alumina fine particles, titania fine particles, tin oxide fine particles, antimony-doped tin oxide (abbreviated name: ATO) fine particles, zinc oxide fine particles, etc., and are preferably silica fine particles. The silica particles are preferably amorphous silica. Examples of amorphous silica fine particles include fumed silica fine particles and colloidal silica. The silica fine particles may be surface modified. The average primary particle diameter of the silica fine particles is preferably 200 nm or less, and more preferably 100 nm or less. The lower limit of the average primary particle of silica fine particles is not particularly limited, but may be, for example, 1 nm or more.

The curable resin composition may contain one or two or more solvents. Solvents include, for example, alcohols (e.g., methanol, ethanol, propanol, isopropanol, n-butanol, s-butanol, t-butanol, benzyl alcohol, PGME, ethylene glycol), ketones (acetone, methyl ethyl ketone (MEK), Cyclohexanone, methyl isobutyl ketone, diacetone alcohol, cycloheptanone, diethyl ketone, etc.), ethers (1,4-dioxane, dioxolane, diisopropyl etherdioxane, tetrahydrofuran, etc.), aliphatics Hydrocarbons (hexane, etc.), alicyclic hydrocarbons (cyclohexane, etc.), aromatic hydrocarbons (toluene, xylene, etc.), halogenated carbons (dichloromethane, dichloroethane, etc.), esters (methyl formate, methyl acetate, ethyl acetate) , propyl acetate, butyl acetate, ethyl lactate, etc.), cellosolves (methyl cellosolve, ethyl cellosolve, butyl cellosolve, etc.), cellosolve acetates, sulfoxides (dimethyl sulfoxide, etc.), amides (dimethylformamide, dimethylacetamide, etc.).

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

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

The thickness of the surface treatment layer such as the 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 even more preferably 1 μm or more. It is less than 10 μm.

<Polarizer>

In this specification, “polarizing plate” refers to an optical laminated body containing a polarizer and a thermoplastic resin film laminated on one side or both sides. In the polarizing plate, the polarizer and the thermoplastic resin film are laminated through an adhesive layer. The adhesive layer is a layer formed from an adhesive composition, for example, a layer of a cured product of an adhesive composition.

The polarizing plate may contain films or layers other than the polarizer and the thermoplastic resin film.

The polarizing plate according to the present invention includes a polarizer, an adhesive layer, and the optical film according to the present invention in this order. Usually, the polarizer and the adhesive layer are in contact with each other, and the adhesive layer and the optical film are in contact with each other. Since the polarizing plate according to the present invention uses the optical film according to the present invention as a protective film for the polarizer, the adhesion between the polarizer and the optical film can be improved, and thereby the durability of the polarizing plate can be improved. there is. In particular, the polarizing plate according to the present invention can have good adhesion between the polarizer and the optical film even when exposed to a high temperature and high humidity environment, and thereby, durability in a high temperature and high humidity environment can be improved.

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

〔1〕Configuration of polarizer

An example of the layer structure of the polarizing plate according to the present invention is shown in Figures 1 and 2.

As shown in Figure 1, the polarizing plate according to the present invention includes a polarizer 30, a first adhesive layer 15, and a first thermoplastic resin film 10, which is an optical film according to the present invention, in this order. That is, it may include a polarizer 30 and a first thermoplastic resin film 10 that is laminated and bonded to one side of the polarizer 30 through a first adhesive layer 15.

A primer layer may be interposed between the first adhesive layer 15 and the first thermoplastic resin film 10, and the first adhesive layer 15 and the first thermoplastic resin film 10 may be in direct contact. It is preferable that the polarizer 30 and the first adhesive layer 15 are in direct contact with each other.

In addition, as shown in Figure 2, the polarizing plate according to the present invention is a polarizer 30 and a first thermoplastic resin film, which is an optical film according to the present invention, which is laminated and bonded to one side of the polarizer 30 through a first adhesive layer 15. (10) and a second thermoplastic resin film (20) laminated and bonded to the other side of the polarizer (30) via a second adhesive layer (25).

It is preferable that the first adhesive layer 15 and the first thermoplastic resin film 10 are in direct contact with each other. It is preferable that the polarizer 30 and the first adhesive layer 15 are in direct contact with each other. It is preferable that the second adhesive layer 25 and the second thermoplastic resin film 20 are in direct contact with each other. It is preferable that the polarizer 30 and the second adhesive layer 25 are in direct contact with each other.

The polarizing plate according to the present invention is preferably inserted into the image display device so that the first thermoplastic resin film 10 side is the viewing side. That is, the optical film according to the present invention is preferably a protective film laminated on the viewing side of the polarizer 30.

Without being limited to the examples of FIGS. 1 and 2, the polarizing plate according to the present invention may include layers (or films) other than those described above. Other layers include, for example, an adhesive layer laminated on the outer surface of the first thermoplastic resin film 10, the second thermoplastic resin film 20, and/or the polarizer 30; A separate film (also referred to as “release film”) laminated on the outer surface of the adhesive layer; A protection film (also referred to as a “surface protection film”) laminated on the outer surface of the first thermoplastic resin film 10, the second thermoplastic resin film 20, and/or the polarizer 30; Examples include an optical functional film (or layer) laminated on the outer surface of the first thermoplastic resin film 10, the second thermoplastic resin film 20, and/or the polarizer 30 through an adhesive layer or adhesive layer.

〔2〕Polarizer

The polarizer 30 is a film that has the function of selectively transmitting linearly polarized light in one direction from natural light. The polarizer 30 includes, for example, an iodine-based polarizer in which iodine as a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film, and a dye-based polarizer in which a dichroic dye as a dichroic dye is adsorbed and oriented in a polyvinyl alcohol-based resin film. A polarizer and an applied polarizer coated with a dichroic dye in a lyotropic liquid crystal state and oriented and fixed are included. These polarizers are called absorption-type polarizers because they selectively transmit linearly polarized light in one direction from natural light and absorb linearly polarized light in another direction.

The polarizer 30 is not limited to an absorption type polarizer, but is a reflection type polarizer that selectively transmits linearly polarized light in one direction from natural light and reflects linearly polarized light in another direction, or scatters linearly polarized light in another direction. It may be a scattering type polarizer, but an absorption type polarizer is preferable because it provides excellent visibility when the polarizer is applied to an image display device, etc.

Among them, the polarizer 30 is more preferably a polyvinyl alcohol-based polarizer composed of a polyvinyl alcohol-based resin, and a dichroic dye such as iodine or a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film. It is more preferable that it is a polyvinyl alcohol-based polarizer, and it is especially preferable that it is a polyvinyl alcohol-based polarizer in which iodine is adsorbed and oriented on a polyvinyl alcohol-based resin film (polyvinyl alcohol-iodine-based polarizer).

A polyvinyl alcohol-based polarizer can be manufactured by a conventionally known method using a polyvinyl alcohol-based resin film (or layer).

The thickness of the polarizer 30 can be 30 μm or less, and is 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 polarizer 30 is usually 2 μm or more. Reducing the thickness of the polarizer 30 is advantageous for reducing the thickness of the polarizing plate and, by extension, the image display device to which it is applied.

[3] Second thermoplastic resin film

The second thermoplastic resin film 20 is made of a light-transmitting (preferably optically transparent) thermoplastic resin, such as chain polyolefin-based resin (polyethylene resin, polypropylene-based resin, etc.), cyclic polyolefin-based resin (norbornene-based resin) polyolefin-based resins such as resins, etc.; Cellulose ester-based resins such as triacetyl cellulose and diacetyl cellulose; Polyester resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polycarbonate-based resin; It may be a film made of (meth)acrylic resin, etc.

The second thermoplastic resin film 20 may be an optical film according to the present invention.

When the second thermoplastic resin film 20 is a (meth)acrylic resin film, the resin component constituting the second thermoplastic resin film 20 may be different in composition from the resin component constituting the optical film according to the present invention. good night.

The second thermoplastic resin film 20 may be an unstretched film or a uniaxially or biaxially stretched film. The biaxial stretching may be simultaneous biaxial stretching in which the material is stretched simultaneously in two stretching directions, or may be sequential biaxial stretching in which the material is stretched in a first direction and then stretched in a second direction different from this.

The second thermoplastic resin film 20 may be a protective film that serves to protect the polarizer 30, or may be a protective film that also has an optical function such as a retardation film. For example, a retardation film with an arbitrary retardation value can be obtained by stretching the film made of the thermoplastic resin (uniaxial stretching, biaxial stretching, etc.) or forming a liquid crystal layer on the thermoplastic resin film.

The second thermoplastic resin film 20 may contain additives as needed. Additives include, for example, lubricants, anti-blocking agents, heat stabilizers, antioxidants, ultraviolet absorbers, antistatic agents, impact resistance improvers, surfactants, mold release agents, etc.

In one embodiment, the first thermoplastic resin film 10 is an optical film according to the present invention, and the second thermoplastic resin film 20 is a polyolefin-based resin film (preferably, a cyclic polyolefin-based resin film), It is a cellulose ester-based resin or polyester-based resin film.

In another embodiment, the first thermoplastic resin film 10 is an optical film according to the present invention, and the second thermoplastic resin film 20 is a (meth)acrylic resin film. This (meth)acrylic resin film may be an optical film according to the present invention.

The second thermoplastic resin film 20 has a coating layer (surface treatment) such as a hard coat layer, an anti-glare layer, an anti-reflection layer, a light diffusion layer, an anti-static layer, an anti-pollution layer, and a conductive layer on its outer surface (the surface opposite to the polarizer 30). layer) may be provided.

The thickness of the second 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, and still more preferably 15 μm or more. 65 It is less than μm. The thickness of the second thermoplastic resin film 20 may be 60 μm or less, and may be 50 μm or less. Reducing the thickness of the second thermoplastic resin film 20 is advantageous for reducing the thickness of the polarizing plate and, by extension, the image display device to which it is applied.

[4] Manufacturing of polarizing plate and adhesive layer

By laminating and adhering the first thermoplastic resin film 10, which is an optical film according to the present invention, to one side of the polarizer 30 through the first adhesive layer 15, a polarizing plate having the configuration shown in FIG. 1 can be obtained. By further laminating and adhering the second thermoplastic resin film 20 to the other side of the polarizer 30 through the second adhesive layer 25, a polarizing plate having the configuration shown in FIG. 2 can be obtained.

When manufacturing a polarizing plate having both the first thermoplastic resin film 10 and the second thermoplastic resin film 20 (hereinafter, these are collectively referred to simply as “thermoplastic resin films”), these thermoplastic resin films are manufactured in steps. You may laminate and bond one side at a time, or you may laminate and bond thermoplastic resin films on both sides simultaneously.

Adhesive compositions that form the first adhesive layer 15 and the second adhesive layer 25 include water-based adhesives or active energy ray-curable adhesives. The adhesive composition forming the first adhesive layer 15 and the adhesive composition forming the second adhesive layer 25 may be the same or different.

The adhesive used for adhering the optical film and polarizer according to the present invention is preferably an active energy ray-curable adhesive.

Examples of water-based adhesives include conventionally known adhesive compositions using polyvinyl alcohol-based resin or urethane resin as the main component. An active energy ray-curable adhesive is an adhesive that hardens by irradiation of active energy rays such as ultraviolet rays, visible light, electron beams, and X-rays. When using an active energy ray-curable adhesive, the adhesive layer that the polarizing plate has is a cured product layer of the adhesive.

The active energy ray-curable adhesive may be an adhesive that contains an epoxy-based compound that hardens by cationic polymerization as a curable component, and is preferably an ultraviolet-curable adhesive that contains this epoxy-based compound as a curable component. An epoxy-based compound refers to a compound having an average of one or more, preferably two or more, epoxy groups in the molecule. The epoxy-based compound may be used alone or in combination of two or more types.

Examples of the epoxy-based compound include hydrogenated epoxy-based compounds obtained by reacting epichlorohydrin with an alicyclic polyol obtained by hydrogenating the aromatic ring of an aromatic polyol (glycidyl ether of a polyol having an alicyclic ring); Aliphatic epoxy-based compounds such as polyglycidyl ethers of aliphatic polyhydric alcohols or their alkylene oxide adducts; and alicyclic epoxy-based compounds, which are epoxy-based compounds having one 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 or together with the epoxy compound. Examples of the (meth)acrylic compound include (meth)acrylate monomers having one or more (meth)acryloyloxy groups in the molecule; Examples include (meth)acryloyloxy group-containing compounds, such as (meth)acrylate oligomer, which is obtained by reacting two or more types of functional group-containing compounds and has at least two (meth)acryloyloxy groups in the molecule.

When the active energy ray-curable adhesive contains an epoxy-based compound that hardens by cationic polymerization as a curable component, it is preferable to contain a photocationic polymerization initiator. Examples of photocationic polymerization initiators include aromatic diazonium salts; Onium salts such as aromatic iodonium salts and aromatic sulfonium salts; An iron-allene complex, etc. can be mentioned.

When the active energy ray-curable adhesive contains a radical polymerizable component such as a (meth)acrylic compound, it is preferable to contain a radical photopolymerization initiator. Examples of the radical photopolymerization initiator include acetophenone-based initiator, benzophenone-based initiator, benzoin ether-based initiator, thioxanthone-based initiator, xanthone, fluorenone, camphorquinone, benzaldehyde, anthraquinone, etc.

The adhesion of the polarizer 30 and the thermoplastic resin film is performed by applying an adhesive composition to the bonding surface of the polarizer 30 and/or the bonding surface of the thermoplastic resin film, or by injecting the adhesive composition between the polarizer 30 and the thermoplastic resin film. It may include a process of overlapping both films through a layer of adhesive composition and bonding them by pressing them from the top and bottom using, for example, a bonding roll.

For forming the adhesive composition layer, various coating methods such as doctor blade, wire bar, die coater, comma coater, and gravure coater can be used. Additionally, a method may be used in which the polarizer 30 and the thermoplastic resin film are continuously supplied so that their bonding surfaces are on the inside, and the adhesive composition is softened in the meantime.

Before applying the adhesive composition, easy adhesion treatment such as saponification treatment, corona discharge treatment, plasma treatment, flame treatment, primer treatment, anchor coating treatment, etc. on one or both sides of the bonding surface of the polarizer 30 and the thermoplastic resin film ( Surface activation treatment) may be used.

When using an active energy ray-curable adhesive, the adhesive composition layer is cured by irradiating active energy rays.

The light source used to irradiate active energy rays may be any that can generate ultraviolet rays, electron beams, X-rays, etc. In particular, low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high pressure mercury lamps, chemical lamps, black light lamps, microwave excited mercury lamps, metal halide lamps, etc., which have an emission distribution in a wavelength of 400 nm or less, are suitably used.

The thickness of the first adhesive layer 15 and the second adhesive layer 25 is, for example, 0.1 μm or more and 100 μm or less in the polarizing plate, preferably 0.5 μm or more and 80 μm or less, and more preferably 1 μm. At least 60 μm or less, more preferably 2 μm or more and 50 μm or less. From the viewpoint of reducing the thickness of the polarizing plate, it is also desirable to set the thickness of the adhesive layer to 30 μm or less, and further preferably 20 μm or less. When using a water-based adhesive, the thickness of the adhesive layer may be smaller than the above.

The first adhesive layer 15 and the second adhesive layer 25 may have the same or different thicknesses.

[5] Other components of the polarizer

〔5-1〕Optical functional film

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

As described above, the second thermoplastic resin film 20 may also serve as a retardation film, but the retardation film may be laminated separately from the thermoplastic resin film. In the latter case, the retardation film can be laminated on the outer surface of the second thermoplastic resin film 20 through a pressure-sensitive adhesive layer or adhesive layer. Additionally, a retardation film may be laminated instead of the second thermoplastic resin film 20. For example, in a single-sided protective polarizing plate in which a first thermoplastic resin film 10 is bonded to one side of the polarizer 30 shown in FIG. 1, a retardation film is bonded to the other side of the polarizer 30. It is one composition. In this case, the retardation film can be laminated on the surface of the polarizer 30 through a pressure-sensitive adhesive layer or adhesive layer.

Examples of the retardation film include a birefringent film made of a stretched film of a light-transmitting thermoplastic resin; A film in which discotic liquid crystal or nematic liquid crystal is aligned and fixed; Examples include those in which the liquid crystal layer is formed on a base film.

The base film is usually a film made of a thermoplastic resin, and an example of the thermoplastic resin is a cellulose ester-based resin such as triacetylcellulose.

As the thermoplastic resin that forms the birefringent film, those described for the second thermoplastic resin film 20 can be used.

Examples of other optical functional films (optical members) that can be included in the polarizing plate include a light collection plate, a brightness enhancing film, a reflective layer (reflective film), a transflective reflective layer (transflective reflective film), and a light diffusion layer (light diffusion film). These are generally installed when 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 according to the present invention may include an adhesive layer for bonding it to an image display element such as a liquid crystal cell or an organic EL element, or to another optical member. The adhesive layer is on the outer surface of the polarizer 30 (the surface opposite to the first thermoplastic resin film 10 side) in the polarizing plate with the configuration shown in FIG. 1, and on the first thermoplastic plate in the polarizing plate with the configuration shown in FIG. 2. It can be laminated on the outer surface of the resin film 10 or the second thermoplastic resin film 20.

In the polarizing plate according to one preferred embodiment, the adhesive layer is laminated on the outer surface of the second thermoplastic resin film 20, that is, on the surface opposite to the first thermoplastic resin film 10 with respect to the polarizer 30. . In this embodiment, when the polarizing plate is bonded to the image display element, the polarizing plate is bonded to the image display element through the adhesive layer so that the first thermoplastic resin film 10 side is the viewing side.

As the adhesive used in the adhesive layer, one using (meth)acrylic resin, silicone resin, polyester resin, polyurethane resin, polyether resin, etc. as the base polymer can be used. Among them, (meth)acrylic adhesives are preferable from the viewpoints of transparency, adhesiveness, reliability, weather resistance, heat resistance, reworkability, etc.

The thickness of the adhesive layer is determined depending on its adhesive strength, etc., but is preferably in the range of 1 μm to 50 μm, and is preferably 2 μm to 40 μm.

The polarizing plate may include a separate film laminated on the outer surface of the adhesive layer. The separate film may be a film made of a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, or a polyester-based resin such as polyethylene terephthalate. Among them, stretched films of polyethylene terephthalate are preferable.

The adhesive layer may, if necessary, contain fillers made of glass fibers, glass beads, resin beads, metal powders or other inorganic powders, pigments, colorants, antioxidants, ultraviolet absorbers, antistatic agents, etc.

〔5-3〕Protect film

The polarizing plate according to the present invention may include a protection film to protect its surface (thermoplastic resin film surface, polarizer surface, etc.). The protective film is peeled and removed for each adhesive layer it has, for example, after the polarizing plate is bonded to the image display element or other optical member.

In a preferred embodiment, the polarizing plate is laminated on the surface of the first thermoplastic resin film 10, which is the optical film according to the present invention.

The protective film is composed of, for example, a base film and an adhesive layer laminated thereon. Regarding the adhesive layer, the above description is cited.

The resin constituting the base film may be, for example, a thermoplastic resin such as a polyethylene-based resin such as polyethylene, a polypropylene-based resin such as polypropylene, a polyester-based resin such as polyethylene terephthalate or polyethylene naphthalate, or a polycarbonate-based resin. there is. Preferably, it is a polyester resin such as polyethylene terephthalate.

Example

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. In the examples, % and parts indicating content or usage are based on mass unless otherwise specified. The thickness of the film and 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) with a syndiotacticity (rr) of 76% in 3-character form.

· (Meth)acrylic resin (B-1): Radical copolymer with a syndiotacticity (rr) of 48% in the three-character form of methyl methacrylate/methyl acrylate = 97/3 (mass ratio)

· Elastomer component (C): (meth)acrylic rubber particles, which are (meth)acrylic multilayer polymers with a three-layer structure (first layer (innermost layer): copolymer of methyl methacrylate, methyl acrylate, and allyl methacrylate ( Mass ratio 93.8/6.0/0.2)/2nd layer: copolymer of butyl acrylate, styrene, and allyl methacrylate (mass ratio 80.6/17.4/2.0)/3rd layer (outermost layer): copolymer of methyl acrylate and ethyl acrylate (mass ratio 80.6/17.4/2.0) Mass ratio 94/6))

An unstretched resin film (resin layer) with a thickness of 50 μm obtained 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). produced.

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

Pentaerythritol triacrylate 60 copies,

Multifunctional urethanated acrylate (reaction product of hexamethylene diisocyanate and pentaerythritol triacrylate) 40 copies

With respect to the above ultraviolet curable resin composition, 2.5 parts of “Omnirad 184” (manufactured by IGM Resins B.V.) as a photoradical polymerization initiator and “Omnirad 819” (manufactured by IGM Resins B.V.) as a solid content per 100 parts of the resin solid content. After adding and mixing 1 part, it was applied to one side of the resin film using a bar coater and dried at 80°C for 3 minutes. The dried applied layer was irradiated with ultraviolet rays at an accumulated light amount of 200 mJ/cm2 using an “H Bulb” lamp manufactured by Fusion as a light source, and optical film I in which a hard coat layer was formed on the surface of the resin layer was produced. The film thickness of the hard coat layer monolayer was 5 μm.

(2) Production of polarizer

The surface of the optical film I (the surface opposite to the hard coat layer) was subjected to corona treatment, and curable adhesive composition A was applied to the corona-treated surface using an adhesive coating device. The obtained coating layer and a polyvinyl alcohol-iodine-based polarizer with a thickness of 23 μm were laminated using a nip roll to obtain a polarizer with optical film I. In the polarizer with optical film I, the mechanical flow direction (MD direction) of optical film I and the absorption axis of the polarizer are parallel.

Next, the surface of a 50 μm thick retardation film made of cyclic polyolefin resin (trade name “ZEONOR” manufactured by Nippon Zeon Co., Ltd.) is subjected to corona treatment, and curable adhesive composition B is applied to the corona-treated surface using an adhesive coating device. It was pottered using. The obtained coating layer and the polarizer surface of the polarizer with optical film I were laminated using a nip roll to obtain a laminate. In the above laminate, the mechanical flow direction (MD direction) of the retardation film and the absorption axis of the polarizer are parallel.

From the retardation film side of this laminate, the total integrated light amount (integrated amount of light irradiation intensity in the wavelength range of 320 to 400 nm) is about 200 mJ/cm2 (measurement using UV Power PuckII manufactured by FusionUV). The layer of curable adhesive composition B and the layer of curable adhesive composition A were cured by irradiating phosphorus ultraviolet rays (UVB) to produce a polarizing plate. Additionally, the thickness of the cured layer of curable adhesive composition A was about 3 μm, and the thickness of the cured layer of curable adhesive composition B was about 3 μm.

Curable adhesive composition A is 20 parts of 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (trade name "Celoxide 2021P" manufactured by Daicel Co., Ltd.), neopentyl glycol diglycidyl ether. (manufactured by Nagase Chemtex Co., Ltd., brand name “EX-211L”) 70 parts, 4-hydroxybutyl vinyl ether (manufactured by Nippon Carbide, brand name “HBVE”) 2 parts, methyl methacrylate-glycidyl methacrylate Prepared by mixing and defoaming 8 parts of ether copolymer (cationic polymerizable polymer) (trade name: “Maproof G-01100” manufactured by Nichiyu) and 2.25 parts of solid content of photopolymerization initiator (trade name: “CPI-100P” manufactured by San-Apro Co., Ltd.) did.

Curable adhesive composition B is 1,4-butanedioldi, based on 100 parts of 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate (trade name "Celoxide 2021P" manufactured by Daicel Co., Ltd.) It was prepared by mixing and defoaming 25 parts of glycidyl ether (trade name "EX-214L" manufactured by Nagase Chemtex Co., Ltd.) and 2.8 parts of solid content of a photopolymerization initiator (trade name "CPI-100P" manufactured by San-Apro Co., Ltd.).

<Example 2>

(1) Production of optical film II

An unstretched resin film (resin layer) with a thickness of 50 μm is prepared 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). ) was produced. As the (meth)acrylic resin (A), (meth)acrylic resin (B-1), and elastomer component (C), the same ones as in Example 1 were used. A hard coat layer was formed in the same manner as in Example 1 except for using this resin film, and optical film II was produced.

(2) Production of polarizer

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

<Comparative Example 1>

(1) Production of optical film III

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

(2) Production of polarizer

A polarizing plate was produced in the same manner as in Example 1 except that Optical Film III was used instead of Optical Film I.

<Example 3>

(1) Fabrication of optical film IV

The following raw materials were prepared.

· (Meth)acrylic resin (B-2): Radical copolymer with a syndiotacticity (rr) of 51% in 3-character form of methyl methacrylate/methyl acrylate = 98.6/1.4 (mass ratio)

An unstretched resin film (resin layer) with a thickness of 60 μm is prepared 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). ) was produced. The same (meth)acrylic resin (A) and elastomer component (C) as in Example 1 were used. A hard coat layer was formed in the same manner as in Example 1 except for using this resin film, and optical film IV was produced.

(2) Production of polarizer

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

<Example 4>

(1) Production of optical film V

An unstretched resin film (resin layer) with a thickness of 60 μm is obtained by melt extrusion 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). ) was produced. The same (meth)acrylic resin (A) and elastomer component (C) as in Example 1 were used. A hard coat layer was formed in the same manner as in Example 1 except for using this resin film, and optical film V was produced.

(2) Production of polarizer

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

<Example 5>

(1) Fabrication of optical film VI

An unstretched resin film (resin layer) with a thickness of 60 μm is prepared by melt extrusion 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). ) was produced. The same (meth)acrylic resin (A) and elastomer component (C) as in Example 1 were used. A hard coat layer was formed in the same manner as in Example 1 except for using this resin film, and optical film VI was produced.

(2) Production of polarizer

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

<Example 6>

(1) Production of optical film VII

An unstretched resin film (resin layer) with a thickness of 60 μm is prepared 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). ) was produced. The same (meth)acrylic resin (A) and elastomer component (C) as in Example 1 were used. A hard coat layer was formed in the same manner as in Example 1 except for using this resin film, and optical film VII was produced.

(2) Production of polarizer

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

<Measurement and evaluation>

(1) Measurement of tensile modulus of optical film

(1-1) Measurement of tensile modulus in MD direction at 23°C

A rectangular test piece with a length of 100 mm x a width of 10 mm was cut from the optical film obtained above. The longitudinal direction of the test piece is parallel to the MD direction of the optical film and is parallel to the absorption axis of the polarizer of the produced polarizing plate. The width direction of the test piece is parallel to the TD direction (direction perpendicular to the MD direction) of the optical film and is perpendicular to the absorption axis of the polarizer of the produced polarizing plate. Next, both ends of the test piece in the longitudinal direction (MD direction of the optical film) are clamped between the upper and lower grippers of a tensile tester (Autograph AG-1S tester manufactured by Shimadzu Corporation) so that the gap between the grippers is 5 cm, and the test piece is placed at 23°C. Under the environment, the test piece was stretched in the longitudinal direction (MD direction of the optical film) at a tensile speed of 50 mm/min, and from the slope of the initial straight line in the obtained stress-strain curve, the elastic modulus in the MD direction of the optical film at 23°C (Tensile modulus) [MPa] was calculated.

(1-2) Measurement of tensile modulus in TD direction at 23°C

A rectangular test piece with a length of 100 mm x a width of 10 mm was cut from the optical film obtained above. The longitudinal direction of the test piece is parallel to the TD direction of the optical film and is perpendicular to the absorption axis of the polarizer of the produced polarizing plate. The width direction of the test piece is parallel to the MD direction of the optical film and is parallel to the absorption axis of the polarizer of the produced polarizing plate. Next, both ends of the test piece in the longitudinal direction (TD direction of the optical film) are clamped between the upper and lower grippers of a tensile tester (Autograph AG-1S tester manufactured by Shimadzu Corporation) so that the gap between the grippers is 5 cm, and the test piece is placed at 23°C. Under the environment, the test piece was stretched in the longitudinal direction (TD direction of the optical film) at a tensile speed of 50 mm/min, and from the slope of the initial straight line in the obtained stress-strain curve, the elastic modulus in the TD direction of the optical film at 23°C (Tensile modulus) [MPa] was calculated.

(1-3) Measurement of tensile modulus at 80°C

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

The tensile modulus of elasticity in the MD direction at each temperature is shown in the “MD” column of Table 1, and the tensile modulus of elasticity in the TD direction is shown in the “TD” column of Table 1. Additionally, the value obtained by dividing the tensile modulus in the TD direction by the tensile modulus in the MD direction is shown in the “TD/MD” column in Table 1.

(2) Measurement of Charpy impact strength of optical films

A rectangular test piece with a length of 100 mm x a width of 10 mm was cut from the optical film obtained above. Using the obtained test piece, a Charpy impact test was conducted in accordance with ISO179-1 and JISK7111-1 using a hammer 1J (rotational moment: 0.540116 N·m) in an environment with a temperature of 23°C and a relative humidity of 50% RH. . Absorbed energy (kJ/m2) was measured 10 times and the average value was adopted. The results are shown in Table 1.

(3) Measurement of pencil hardness of optical films

In accordance with JIS K5600-5-4, it was measured using a No553-M1 electric pencil scratch hardness tester manufactured by Yasuda Seki Manufacturing. First, the optical film was fixed with tape on a glass plate with the hard coat layer facing upward, a pencil was set at 45 degrees, and a load of 500 g was applied to scratch the sample surface (hard coat layer surface). The test was conducted five times using pencils of the same hardness. Additionally, the hardness of the pencil was changed from F to 2H, and the same scratch test was performed. The film with the surface scratched was placed on a blackboard, and the presence or absence of damage on the surface of the film was observed by reflection of fluorescent light. The maximum pencil hardness at which no damage occurred in 4 or more out of 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 (opposite to the retardation film) of the obtained polarizing plate. The obtained polarizing plate with an adhesive layer was cut into a size of 200 mm in length (parallel to the absorption axis direction of the polarizer) x 25 mm in width, and the adhesive layer was bonded to a glass plate to obtain a laminate. It was placed in an environment with a temperature of 23°C and a relative humidity of 50% RH for 24 hours. After that, a cutter blade was inserted between the polarizer and the optical film of the obtained laminate, and 30 mm was peeled from the end in the longitudinal direction. The peeled portion was held by the grip part of the tester, and the lower part of the grip held a glass plate. For the test piece in this state, in an atmosphere of a temperature of 23°C and a relative humidity of 55%, in accordance with JIS K 6854-2:1999 "Adhesive - Peel adhesive strength test method - Part 2: 180 degree peel", the grip movement speed was 300. A peeling test was performed at mm/min to determine the average peeling force (unit: N/25 mm) over a length of 60 mm excluding 30 mm of the grip portion, and this was taken as the peeling strength between the polarizer 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 (opposite to the retardation film) of the obtained polarizing plate. The obtained polarizing plate with an adhesive layer was cut into a size of 200 mm in length (parallel to the absorption axis direction of the polarizer) x 25 mm in width, and the adhesive layer was bonded to a glass plate to obtain a laminate. The obtained laminate was placed in a high-temperature, high-humidity environment with a temperature of 80°C and a relative humidity of 90% RH for 24 hours, and then placed in an environment with a temperature of 23°C and a relative humidity of 50% RH for 24 hours. After that, a cutter blade was inserted between the polarizer of the obtained laminate and the optical film, and 30 mm was peeled from the end in the longitudinal direction. The peeled part was held by the grip part of the tester, and the lower part of the grip held a glass plate. For the test piece in this state, in an atmosphere of a temperature of 23°C and a relative humidity of 55%, in accordance with JIS K 6854-2:1999 "Adhesive - Peel adhesive strength test method - Part 2: 180 degree peel", the grip movement speed was 300. A peeling test was performed at mm/min, the average peeling force (unit: N/25 mm) over a length of 60 mm excluding 30 mm of the grip portion was determined, and this was taken as the peeling strength between the polarizer and the optical film. The results are shown in Table 1.

10: first thermoplastic resin film, 15: first adhesive layer, 20: second thermoplastic resin film, 25: second adhesive layer, 30: polarizer.

Claims (6)

An optical film comprising a resin layer containing (meth)acrylic resin (A), (meth)acrylic resin (B), and 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 has the following formula [1 ]:
A/(A+C)<0.6 Equation [1]
Optical film that meets the requirements. The method according to claim 1, wherein the content of the (meth)acrylic resin (B) in the resin layer is expressed as B (parts by mass), using the following formula [2]:
0.05≤A/(A+B)≤0.4 Equation [2]
An optical film that further satisfies the requirements. The optical film according to claim 1 or 2, wherein the elastomer component (C) is rubber particles. The optical film according to any one of claims 1 to 3, further comprising a surface treatment layer laminated on the resin layer. The optical film according to any one of claims 1 to 4, which is a protective film for a polarizer. A polarizing plate comprising a polarizer, an adhesive layer, and the optical film according to any one of claims 1 to 5 in this order.