JP4881105B2 - Optical film, polarizing plate, and image display device - Google Patents

Description

  The present invention relates to an optical film, a polarizing plate using the optical film, and an image display device such as a liquid crystal display device, an organic EL display device, and a PDP including at least one polarizing plate.

  Optical films such as retardation films and polarizer protective films are used in liquid crystal display devices, organic EL display devices, image display devices such as PDPs, and the like. The optical film is required to have various optical properties, mechanical strength, transparency, heat resistance, moisture resistance, and the like depending on its use. In particular, in recent years, development of an optical film suitable for increasing the size of a liquid crystal display and development of a thin optical film used for mobile devices are required.

As for an optical film, one kind of film may be used alone, but in many cases, it is used by being combined with another film (for example, see Patent Documents 1 and 2). Bonding with other films for this composite is generally performed using an adhesive. However, depending on the type of film, bonding with an adhesive cannot be performed sufficiently, and problems such as peeling may occur.
JP 2005-326831 A JP 2005-352403 A

  The present invention has been made in order to solve the above-described conventional problems, and an object of the present invention is to provide an optical film excellent in adhesiveness of a bonded product, and polarization using such an optical film. It is in providing a board and an image display device.

The present inventors have intensively studied to solve the above problems. As a result, an optical film having a specific surface orientation on the surface, specifically, an optical film having a Dxz of 1240 cm ⁻¹ in a polarized ATR / FT-IR spectrum measured at an incident angle of 60 degrees is 1.05 or more Then, the present inventors have found that the above problems can be solved, and have completed the present invention.

The optical film of the present invention is an optical film in which at least one surface is oriented out of plane, and a Dxz of 1240 cm ⁻¹ in a polarized light ATR / FT-IR spectrum measured at an incident angle of 60 degrees is 1.05 or more. is there.

In a preferred embodiment, the Dxy of 1240 cm ⁻¹ in the polarized ATR / FT-IR spectrum measured at an incident angle of 60 degrees is 1.00 or more.

  In a preferred embodiment, the out-of-plane orientation is formed by a chemical orientation treatment.

  In a preferred embodiment, the optical film is an acrylic film.

  In a preferred embodiment, the optical film is a polarizer protective film.

  According to another aspect of the present invention, a polarizing plate is provided. The polarizing plate of this invention contains the polarizer formed from polyvinyl alcohol-type resin, and the optical film of this invention which is a polarizer protective film.

  According to another aspect of the present invention, an image display device is provided. The image display device of the present invention includes at least one polarizing plate of the present invention.

According to the present invention, it is possible to provide an optical film excellent in adhesiveness of a bonded product, and to provide a polarizing plate and an image display device using such an optical film.
Such an effect is that the optical film having a specific surface orientation on the surface, specifically, the Dxz of 1240 cm ⁻¹ in the polarized ATR / FT-IR spectrum measured at an incident angle of 60 degrees is 1.05 or more. It can be expressed by the optical film.
The above optical characteristics can be preferably obtained by performing a chemical orientation treatment on the surface of the optical film.

  Hereinafter, although preferable embodiment of this invention is described, this invention is not limited to these embodiment.

[Optical film]
An effective method for evaluating the structure of the film surface is a polarized ATR / FT-IR spectrum.

  In the present invention, the polarized ATR / FT-IR spectrum is obtained by using an FT-IR spectrum (Fourier transform infrared absorption spectrum) measuring device (FT-IR manufactured by Digilab, model number: FTS3000) with an infrared polarizer and a variable angle hemispherical ATR. The measurement was performed under the following conditions using a device to which an accessory (manufactured by HARIC, trade name: Seagull, internal reflection element: hemispherical Ge prism) was attached. As a measurement sample, a sample piece cut out from a sample film in an approximately 30 mm square parallel to the MD direction was used.

(FT-IR measurement conditions)
Measurement resolution: 2 cm ^-1
Integration count: 256 times

(Polarization ATR measurement conditions)
Incident angle: 60 degrees Polarization direction: p-direction (parallel polarization) and s-polarization (vertical polarization)
Measurement direction: MD direction and TD direction

In the present invention, the polarized ATR / FT-IR spectrum obtained by the above measurement method, that is, the parallel absorption spectrum by parallel polarization (the infrared absorption spectrum measured by matching the polarization direction of the infrared light and the stretching axis). ) And the vertical absorption spectrum (infrared absorption spectrum measured with the polarization direction of infrared light and the stretching axis at 90 degrees) and the orientation analysis of the vertical absorption spectrum, X of a specific absorption band (1240 cm ^{−1 in the} present invention) The extinction coefficients kx, ky, and kz in the directions of the axis, Y axis, and Z axis were calculated, and Dxy (= kx / ky) and Dxz (= kx / kz) in the absorption band were obtained.

  Regarding Dxy (= kx / ky), when Dxy ≧ 1.00, it means that parallel dichroism is shown, and when Dxy <1.00, it means that vertical dichroism is shown.

The extinction coefficients kx, ky, and kz can be calculated as follows. That is, the experimental constants of extinction coefficients kx, ky, kz, and ATR in the X-axis, Y-axis, and Z-axis directions of a specific absorption band (1240 cm ^{−1 in the} present invention) are α, β, γ, and the absorbance of the parallel absorption spectrum. Is “A (parallel)”, and the absorbance of the vertical absorption spectrum is “A (vertical)”, the following relational expression is established, which can be calculated from these expressions.

A (parallel) = log _e (αkx + γkz)
A (vertical) = log _e βky
α = {4n ₂ ² (1-n ₂ ² / n ₁ ² sin ² θ)} / {n ₁ ² tan θ (1-n ₂ ² / n ₁ ² sin ² θ) ^1/2 (1-n ₂ ² / N ₁ ² sin ² θ + n ₂ ⁴ cot ² θ / n ₁ ⁴ )}
β = 4n ₂ ² / {n ₁ ² tan θ (1-n ₂ ² / n ₁ ² sin ² θ) ^1/2 (1-n ₂ ² / n ₁ ² )}
γ = 4n ₂ ² / {n ₁ ² tan θ (1-n ₂ ² / n ₁ ² sin ² θ) ^1/2 (1-n ₂ ² / n ₁ ² sin ² θ + n ₂ ⁴ cot ² θ / n ₁ ⁴ )}
n ₁ , n ₂ , and θ are the refractive index of the IRE, the refractive index of the sample, and the incident angle, respectively.

The optical film of the present invention is an optical film in which at least one surface is oriented out of plane, and Dxz of 1240 cm ⁻¹ in a polarized ATR spectrum measured at an incident angle of 60 degrees is 1.05 or more. Since at least one surface only needs to be out-of-plane, only one surface may be out-of-plane or both surfaces may be out-of-plane.

  The above Dxz is preferably 1.10 or more, more preferably 1.20 or more, further preferably 1.30 or more, particularly preferably 1.40 or more, and most preferably 1.50 or more. The upper limit of Dxz can be set to any appropriate range as long as the object of the present invention can be achieved. Preferably it is 9.0 or less.

  When the Dxz is 1.05 or more, an optical film having excellent adhesion of a bonded product can be obtained.

In the present invention, the Dxy of 1240 cm ⁻¹ in the polarized ATR / FT-IR spectrum measured at an incident angle of 60 degrees is preferably 1.00 or more. The Dxy is preferably 1.02 or more, more preferably 1.04 or more, further preferably 1.06 or more, and particularly preferably 1.08 or more. The upper limit of the Dxy can be set to any appropriate range as long as the object of the present invention can be achieved. Preferably it is 4.2 or less.

  The above optical characteristics can be preferably obtained by performing chemical orientation treatment on the surface of the optical film. The chemical orientation treatment is a concept opposite to physical orientation treatment such as rubbing treatment or roll friction treatment. Examples of the chemical alignment treatment include alignment treatment using a chemical reaction, alignment treatment by blending any appropriate component, and the like.

  The chemical orientation treatment in the present invention is preferably an orientation treatment by blending one or two or more resins constituting the film and any appropriate component, specifically, for example, blending of fine particles An alignment treatment by means of. By blending fine particles, the orientation state of the optical film surface can be suitably controlled, and the adhesive interface strength in bonding with other films is significantly improved. The fine particles are preferably nanoscale particles (so-called nanoparticles). As a compounding quantity in the case of mix | blending a fine particle, 1-50 weight% is preferable with respect to the total amount of resin which comprises a film, 5-45 weight% is more preferable, and 10-40 weight% is further more preferable. When the amount is within the above range, the treatment effect of the chemical orientation treatment can be sufficiently exhibited.

  The particle diameter of the fine particles is preferably 1 to 1000 nm, more preferably 10 to 900 nm, still more preferably 50 to 800 nm, and particularly preferably 100 to 700 nm. When the particle diameter of the fine particles is within the above range, the treatment effect of the chemical orientation treatment can be sufficiently exhibited.

  The fine particles are more preferably core-shell type nanoparticles.

  The core-shell type nanoparticles are core-shell type nanoparticles having a core layer made of a rubbery polymer and a shell layer made of a glassy polymer. The Tg of the rubber-like polymer constituting the core layer is preferably 20 ° C. or less, more preferably −60 to 20 ° C., and further preferably −60 to 10 ° C. If the Tg of the rubbery polymer constituting the core layer exceeds 20 ° C, the effects of the present invention may not be exhibited. The glassy polymer constituting the shell layer preferably has a Tg of 50 ° C. or higher, more preferably 50 to 140 ° C., and still more preferably 60 to 130 ° C. When Tg of the glassy polymer constituting the shell layer is lower than 50 ° C., the effect of the present invention may not be exhibited.

  The content ratio of the core layer in the core-shell type nanoparticles is preferably 30 to 95% by weight, more preferably 50 to 90% by weight. The content ratio of the shell layer in the core-shell type nanoparticles is preferably 5 to 70% by weight, more preferably 10 to 50% by weight.

  The core-shell type nanoparticles may contain any appropriate other component as long as the effects of the present invention are not impaired.

  Any appropriate polymerizable monomer can be adopted as the polymerizable monomer for forming the rubber-like polymer constituting the core layer.

  The polymerizable monomer forming the rubbery polymer preferably contains an alkyl (meth) acrylate. The “alkyl (meth) acrylate” is a collective expression of alkyl acrylate or alkyl methacrylate. In the polymerizable monomer forming the rubber-like polymer, the alkyl (meth) acrylate is preferably contained in an amount of 50% by weight or more, more preferably 50 to 99.9% by weight, and 60 to 99.9% by weight. More preferably it is included.

  Examples of the alkyl (meth) acrylate include ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isononyl (meth) acrylate, and lauroyl. Examples thereof include alkyl (meth) acrylates having 2 to 20 carbon atoms in the alkyl group, such as (meth) acrylate and stearyl (meth) acrylate. Among these, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isononyl (meth) acrylate, and the like are preferable alkyl (meth) acrylates having 2 to 10 carbon atoms, such as butyl acrylate and 2-ethylhexyl. Acrylate and isononyl acrylate are more preferable. These may be used alone or in combination of two or more.

  The polymerizable monomer forming the rubbery polymer preferably contains a polyfunctional monomer having two or more vinyl groups in the molecule. In the polymerizable monomer forming the rubbery polymer, the polyfunctional monomer having two or more vinyl groups in the molecule is preferably contained in an amount of 0 to 20% by weight, and preferably contained in an amount of 0.1 to 20% by weight. Is more preferable, 0.1 to 10% by weight is more preferable, and 0.2 to 5% by weight is particularly preferable.

  Examples of the polyfunctional monomer having two or more vinyl groups in the molecule include aromatic divinyl monomers such as divinylbenzene, ethylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, hexanediol di ( Alkane polyols such as (meth) acrylate, oligoethylene glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, trimethylolpropane tri (meth) acrylate, urethane di (meth) acrylate, epoxy di ( And (meth) acrylate. Examples of the polyfunctional monomer having different reactive vinyl groups include allyl (meth) acrylate, diallyl maleate, diallyl fumarate, diallyl itaconate, and the like. Among these, ethylene glycol dimethacrylate, butylene glycol diacrylate, and allyl methacrylate are preferable. These may be used alone or in combination of two or more.

  The polymerizable monomer forming the rubber-like polymer may contain the above-mentioned alkyl (meth) acrylate and other polymerizable monomer copolymerizable with a polyfunctional monomer having two or more vinyl groups in the molecule. good. In the polymerizable monomer forming the rubber-like polymer, the other polymerizable monomer is preferably contained in an amount of 0 to 49.9% by weight, and more preferably 0 to 39.9% by weight.

  Examples of the other monomer include aromatic vinyl such as styrene, vinyl toluene and α-methylstyrene, vinyl cyanide such as aromatic vinylidene, acrylonitrile and methacrylonitrile, vinylidene cyanide, methyl methacrylate, urethane acrylate and urethane. A methacrylate etc. can be mentioned. The other monomer may be a monomer having a functional group such as an epoxy group, a carboxyl group, a hydroxyl group, or an amino group. Specifically, examples of the monomer having an epoxy group include glycidyl methacrylate, and examples of the monomer having a carboxyl group include methacrylic acid, acrylic acid, maleic acid, and itaconic acid. Examples of the monomer having a hydroxyl group include 2-hydroxyethyl methacrylate and 2-hydroxyethyl acrylate. Examples of the monomer having an amino group include diethylaminoethyl methacrylate and diethylaminoethyl acrylate. These may be used alone or in combination of two or more.

  Any appropriate polymerizable monomer can be adopted as the polymerizable monomer for forming the glassy polymer constituting the shell layer.

  The polymerizable monomer forming the glassy polymer preferably contains at least one monomer selected from alkyl (meth) acrylates and aromatic vinyl monomers. Among the polymerizable monomers forming the glassy polymer, at least one monomer selected from alkyl (meth) acrylate and aromatic vinyl monomer is preferably contained in an amount of 50 to 100% by weight, and contained in an amount of 60 to 100% by weight. It is more preferable.

  As said alkyl (meth) acrylate, the C1-C4 thing of alkyl groups, such as methyl acrylate, methyl methacrylate, ethyl methacrylate, is preferable, and methyl methacrylate is more preferable. These may be used alone or in combination of two or more.

  Examples of the aromatic vinyl monomer include styrene, vinyl toluene, α-methyl styrene and the like. Among these, styrene is preferable. These may be used alone or in combination of two or more.

  The polymerizable monomer forming the glassy polymer may contain a polyfunctional monomer having two or more vinyl groups in the molecule. In the polymerizable monomer forming the glassy polymer, the polyfunctional monomer having two or more vinyl groups in the molecule is preferably contained in an amount of 0 to 10% by weight, and preferably contained in an amount of 0.1 to 8% by weight. Is more preferable, and 0.2 to 5% by weight is more preferable.

  Specific examples of the polyfunctional monomer having two or more vinyl groups in the molecule include the same ones as described above.

  The polymerizable monomer forming the glassy polymer may contain the above alkyl (meth) acrylate and another polymerizable monomer copolymerizable with a polyfunctional monomer having two or more vinyl groups in the molecule. good. In the polymerizable monomer forming the glassy polymer, the other polymerizable monomer is preferably contained in an amount of 0 to 50% by weight, and more preferably 0 to 40% by weight.

  Examples of the other monomer include vinyl cyanide such as acrylonitrile and methacrylonitrile, vinylidene cyanide, alkyl (meth) acrylates other than those described above, urethane acrylate, and urethane methacrylate. Moreover, you may have functional groups, such as an epoxy group, a carboxyl group, a hydroxyl group, and an amino group. Examples of the monomer having an epoxy group include glycidyl methacrylate, and examples of the monomer having a carboxyl group include methacrylic acid, acrylic acid, maleic acid, itaconic acid, and the like, and have a hydroxyl group. Examples of the monomer include 2-hydroxy methacrylate and 2-hydroxy acrylate, and examples of the monomer having an amino group include diethylaminoethyl methacrylate and diethylaminoethyl acrylate. These may be used alone or in combination of two or more.

  As a method for producing core-shell type nanoparticles that can be used in the present invention, any suitable method capable of producing core-shell type particles can be adopted. For example, a polymerizable monomer that forms a rubbery polymer constituting the core layer is subjected to suspension polymerization to produce a suspension containing rubbery polymer particles, and then a shell layer is formed in the suspension. And a method of obtaining core-shell type nanoparticles having a multilayer structure in which a glassy polymer is coated on the surface of a rubbery polymer particle by radical polymerization by adding a polymerizable monomer that forms a glassy polymer.

  Any appropriate resin can be adopted as the main component resin constituting the optical film of the present invention as long as the object of the present invention can be achieved. Specifically, for example, transparent resins such as polyester, polyvinyl alcohol, polycarbonate, polyamide, polyimide, polyethersulfone, polysulfone, polystyrene, polynorbornene, polyolefin, acrylic, and acetate Etc. In addition, thermosetting resins such as acrylic, urethane, acrylic urethane, epoxy, and silicone, or ultraviolet curable resins are also included. In addition to this, for example, a glassy polymer such as a siloxane polymer is also included. Moreover, the polymer film as described in Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007) can also be used. As a material for this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and nitrile group in the side chain For example, a resin composition having an alternating copolymer composed of isobutene and N-methylmaleimide and an acrylonitrile / styrene copolymer can be mentioned. The polymer film can be, for example, an extruded product of the resin composition. The “main component” in the present invention is preferably 50 to 99% by weight, more preferably 60 to 98% by weight, and still more preferably 70 to 97% by weight, based on the total amount.

  The resin is preferably transparent and has no color. Specifically, the thickness direction retardation value is preferably −90 nm to +90 nm, more preferably −80 nm to +80 nm, and most preferably −70 nm to +70 nm.

  The optical film of this invention should just be a film comprised with arbitrary appropriate resin in the range which does not impair the effect of this invention. Examples of the resin include acetate resin, polyester resin, polyethersulfone resin, polysulfone resin, polycarbonate resin, polyamide resin, polyimide resin, polyolefin resin, (meth) acrylic resin, and norbornene. Examples thereof include cyclic olefin resins such as resins, polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. Also, thermosetting resins such as acrylic, urethane, acrylic urethane, epoxy, and silicone, or ultraviolet curable resins may be used. These resins may be used alone or in combination of two or more.

  The optical film of the present invention is preferably an acrylic film. The acrylic film referred to in the present invention refers to a film in which the main component of the resin constituting the optical film of the present invention is a (meth) acrylic resin. Here, the “main component” is preferably 50% by weight or more, more preferably 60% by weight or more, still more preferably 70% by weight or more, still more preferably 80% by weight or more, particularly preferably 90% by weight of the total amount of the resin. It means greater than or equal to wt%, most preferably 100 wt%.

  Each of the (meth) acrylic resins may be composed of one kind of resin, or may be composed of two or more kinds of resins. The (meth) acrylic resin has a mass average molecular weight (sometimes referred to as a weight average molecular weight) of preferably 1,000 to 2,000,000, more preferably 5,000 to 1,000,000, still more preferably 10,000 to 500,000, particularly preferably 50,000 to 500,000. It is. If the mass average molecular weight is out of the above range, the effects of the present invention may not be sufficiently exhibited.

  The (meth) acrylic resin preferably has a Tg (glass transition temperature) of 115 ° C. or higher, more preferably 120 ° C. or higher, still more preferably 125 ° C. or higher, and particularly preferably 130 ° C. or higher. By including a (meth) acrylic resin having a Tg (glass transition temperature) of 115 ° C. or higher as a main component, for example, when it is finally incorporated into a polarizing plate, it tends to be excellent in durability. The upper limit value of Tg of the (meth) acrylic resin is not particularly limited, but is preferably 170 ° C. or less from the viewpoint of moldability and the like.

  The (meth) acrylic resin is preferably as the total light transmittance of a molded product obtained by injection molding measured by a method according to ASTM-D-1003 is higher, preferably 85% or more. Preferably it is 88% or more, More preferably, it is 90% or more. If the total light transmittance is less than 85%, the transparency is lowered, and there is a possibility that it cannot be used for the intended purpose.

  The (meth) acrylic resin preferably has high light transmittance, low in-plane retardation Δnd and low thickness direction retardation Rth.

Although it does not specifically limit as said (meth) acrylic-type resin, For example, poly (meth) acrylic acid ester, such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meta ) Acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester- (meth) acrylic acid copolymer, (meth) methyl acrylate-styrene copolymer (MS resin, etc.), alicyclic hydrocarbon group Polymers (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, methyl methacrylate-norbornyl (meth) acrylate copolymer, etc.) and the like can be mentioned. Preferably, (meth) acrylic acid C ₁ containing poly (meth) acrylate C _1-6 alkyl such as poly (meth) acrylate methyl as a main component (50 to 100% by weight, preferably 70 to 100% by weight). _-6 alkyl resin is mentioned, More preferably, the methyl methacrylate resin which has methyl methacrylate as a main component (50-100 weight%, Preferably 70-100 weight%) is mentioned.

  Specific examples of the (meth) acrylic resin include (meth) acrylic resins having a ring structure in the molecule described in, for example, Acrypet VH and Acrypet VRL20A manufactured by Mitsubishi Rayon Co., Ltd., and JP-A-2004-70296. Examples of the resin include high Tg (meth) acrylic resins obtained by intramolecular crosslinking or intramolecular cyclization reaction.

  In the present invention, the (meth) acrylic resin described in JP 2000-230016, JP 2001-151814, JP 2005-146084, JP 2005-314534, etc. A (meth) acrylic resin having a ring structure may be used.

  When the optical film of the present invention is an acrylic film, in the resin constituting the optical film of the present invention, in addition to the above (meth) acrylic resin as a main component, any appropriate within a range not impairing the effects of the present invention Other resins may be included.

  Examples of the other resins include cyclic olefins such as acetate resins, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, and norbornene resins. Resin, polyarylate resin, polystyrene resin, polyvinyl alcohol resin, and mixtures thereof. Also, thermosetting resins such as acrylic, urethane, acrylic urethane, epoxy, and silicone, or ultraviolet curable resins may be used. These resins may be used alone or in combination of two or more.

  The optical film of the present invention may contain any appropriate additive other than the above-described resins. Specifically, for example, ultraviolet absorbers, general compounding agents such as stabilizers, lubricants, processing aids, plasticizers, impact aids, phase difference reducing agents, matting agents, antibacterial agents, fungicides Etc.

  The melting point of the ultraviolet absorber is preferably 110 ° C. or higher, and more preferably 120 ° C. or higher. When the melting point of the ultraviolet absorber is 130 ° C. or higher, there is little volatilization at the time of heat-melting processing, and roll contamination during film production is difficult to occur. The type of the UV absorber is not particularly limited, but a benzotriazole UV absorber having a molecular weight of 400 or more and a triazine UV absorber having a molecular weight of 400 or more are particularly preferable. Examples of commercially available products include “Tinubin 1577” (manufactured by Ciba Specialty Chemicals), “Adeka Stub LA-31” (manufactured by Asahi Denka Kogyo Co., Ltd.), and the like.

  As the retardation reducing agent, for example, a styrene-containing polymer such as acrylonitrile-styrene copolymer is preferable. When the retardation reducing agent is contained in the optical film of the present invention, the addition amount of the retardation reducing agent is 30% by weight or less based on the total amount of the resin in the optical film of the present invention. More preferably, it is 25% by weight or less, more preferably 20% by weight or less. When added beyond this range, visible light may be scattered or transparency may be impaired.

  Any appropriate thickness can be adopted as the thickness of the optical film of the present invention as long as the effects of the present invention are not impaired. Specifically, the thickness of the optical film of the present invention is preferably 20 to 200 μm, more preferably 25 to 180 μm, and further preferably 30 to 140 μm. When the thickness is 20 μm or more, it has appropriate strength and rigidity, and handling properties are good during secondary processing such as laminating and printing. Further, the phase difference caused by the stress at the time of take-up can be easily controlled, and the film can be manufactured stably and easily. When the thickness of the other protective layer is 200 μm or less, film winding is facilitated, and line speed, productivity, and controllability are facilitated.

  In the optical film of the present invention, the haze representing optical transparency is preferably as low as possible, preferably 5% or less, more preferably 3% or less, still more preferably 1.5% or less, and particularly preferably 1% or less. It is. When the haze is 5% or less, it is possible to visually give a good clear feeling to the film. When the haze is 1.5% or less, even when used as a lighting member such as a window, the visibility and the lighting performance are improved. Since both can be obtained, and even when used as a front plate of a display device, the display contents can be visually recognized well, and thus the industrial utility value is high.

  The optical film of the present invention preferably has a higher total light transmittance as measured by a method according to ASTM-D-1003, preferably 85% or more, more preferably 88% or more, and still more preferably 90%. That's it. If the total light transmittance is less than 85%, the transparency is lowered, and there is a possibility that it cannot be used for the intended purpose.

  The optical film of the present invention can be used as a polarizer protective film.

  When the optical film of the present invention is a polarizer protective film, it is preferable that the in-plane retardation Δnd is 3.0 nm or less, the thickness direction retardation Rth is 10.0 nm or less, and the tear strength is 2.0 N / mm or more. . When the in-plane retardation Δnd, thickness direction retardation Rth, and tear strength are within these ranges, both excellent optical properties and excellent mechanical strength can be achieved.

  When the optical film of the present invention is a polarizer protective film, the in-plane retardation Δnd is preferably as small as possible, preferably 2.0 nm or less, more preferably 1.5 nm or less, and even more preferably 1.0 nm or less. is there. When the in-plane retardation Δnd exceeds 3.0 nm, for example, there is a possibility that excellent optical characteristics may not be exhibited. The thickness direction retardation Rth is preferably as small as possible, preferably 7.0 nm or less, more preferably 5.0 nm or less, and still more preferably 3.0 nm or less. If the thickness direction retardation Rth exceeds 10.0 nm, for example, excellent optical characteristics may not be exhibited.

  When the optical film of the present invention is a polarizer protective film, the tear strength is preferably 2.1 N / mm or more, more preferably 2.2 N / mm or more, still more preferably 2.3 N / mm or more, particularly preferably. 2.4 N / mm or more, and most preferably 2.5 N / mm or more. If the tear strength is out of the above range, the excellent mechanical strength may not be exhibited.

When the optical film of the present invention is a polarizer protective film, the moisture permeability is preferably as low as possible, preferably 100 g / m ² · 24 hr or less, more preferably 60 g / m ² · 24 hr or less. If the moisture permeability exceeds 100 g / m ² · 24 hr, the moisture resistance may be inferior.

  When the optical film of the present invention is a polarizer protective film, it may be stretched by longitudinal stretching and / or lateral stretching. By being stretched by longitudinal stretching and / or lateral stretching, it has excellent optical properties, is excellent in mechanical strength, and improves productivity and reworkability.

  The stretching may be stretching by only longitudinal stretching (free end uniaxial stretching) or stretching by only lateral stretching (fixed end uniaxial stretching), but the longitudinal stretching ratio is 1.1 to 3.0 times, and the transverse stretching ratio. Is preferably a sequential stretching or simultaneous biaxial stretching of 1.1 to 3.0 times. In stretching only by longitudinal stretching (free-end uniaxial stretching) and stretching only by lateral stretching (fixed-end uniaxial stretching), the film strength increases only in the stretching direction, and the strength does not increase in the direction perpendicular to the stretching direction. There is a possibility that sufficient film strength as a whole cannot be obtained. The longitudinal stretching ratio is more preferably 1.2 to 2.5 times, and still more preferably 1.3 to 2.0 times. The transverse stretching ratio is more preferably 1.2 to 2.5 times, and still more preferably 1.4 to 2.0 times. When the longitudinal draw ratio and the transverse draw ratio are less than 1.1 times, the draw ratio is too low, and there is a possibility that there is almost no stretching effect. When the longitudinal stretching ratio and the lateral stretching ratio exceed 3.0 times, stretching breakage is likely to occur due to the problem of the smoothness of the film end face.

  The stretching temperature is preferably Tg to (Tg + 30 ° C.) of the film to be stretched. If the stretching temperature is lower than Tg, the film may be broken. If the stretching temperature exceeds (Tg + 30 ° C.), the film may start to melt and paper passing may be difficult.

  The optical film of the present invention may be produced by any method, but the raw material (resin composition) for forming the film is extruded (melt extrusion method such as T-die method or inflation method), cast molding ( A method of producing a film by performing a melt casting method or the like, calendar molding or the like is preferable. Furthermore, you may extend | stretch the obtained film as needed.

  Extrusion molding does not require drying and scattering of the solvent in the adhesive used during processing, such as the organic solvent in the adhesive for dry lamination, as in the case of the dry lamination method. Excellent in productivity. Specifically, a method of forming a film by supplying a resin composition as a raw material to an extruder connected to a T-die, extruding, extruding, taking out by water cooling or contacting with a cooling roll Can be illustrated. The screw type of the extruder may be uniaxial or biaxial, and an additive such as a plasticizer or an antioxidant may be added.

  The extrusion molding temperature can be appropriately set, but when the glass transition temperature of the resin composition as a raw material is Tg (° C.), (Tg + 80) ° C. to (Tg + 180) ° C. is preferable, and (Tg + 100) ° C. to (Tg + 150) ° C. More preferred. If the extrusion molding temperature is too low, the resin does not have fluidity and may not be molded. If the extrusion molding temperature is too high, the resin viscosity will be low, and there may be a problem in production stability such as uneven thickness of the molded product.

  The optical film of the present invention can be used by being laminated on another substrate. For example, it can be laminated by multilayer extrusion molding including an adhesive resin layer or multilayer inflation molding on a substrate such as glass, a polyolefin resin, an ethylene vinylidene copolymer serving as a high barrier layer, or polyester. If the heat-fusibility is high, the adhesive layer may be omitted.

  The optical film of the present invention, for example, besides being used as a polarizer protective film, architectural daylighting members such as windows and carport roofing materials, vehicle daylighting members such as windows, agricultural daylighting members such as greenhouses, lighting members, It can be used by laminating it on display members such as front filters, etc., and it has been conventionally covered with (meth) acrylic resin films. Household appliance casings, vehicle interior members, interior building materials, wallpaper, decorative boards It can also be used by being laminated on entrance doors, window frames, baseboards, and the like.

〔Polarizer〕
The polarizing plate of this invention is a polarizing plate containing the polarizer formed from a polyvinyl alcohol-type resin, and the optical film of this invention as a polarizer protective film. One preferred embodiment of the polarizing plate of the present invention is that, as shown in FIG. 1, one surface of a polarizer 31 is bonded to the optical film 34 of the present invention via an adhesive layer 32 and an easy adhesion layer 33. Thus, the other surface of the polarizer 31 is bonded to the polarizer protective film 36 through the adhesive layer 35. The polarizer protective film 36 may be the optical film of the present invention, or may be any other appropriate polarizer protective film.

  As the polarizer formed from the polyvinyl alcohol-based resin, one obtained by dyeing a polyvinyl alcohol-based resin film with a dichroic substance (typically iodine, a dichroic dye) and uniaxially stretching is used. The polymerization degree of the polyvinyl alcohol resin constituting the polyvinyl alcohol resin film is preferably 100 to 5000, and more preferably 1400 to 4000. The polyvinyl alcohol-based resin film constituting the polarizer can be formed by any suitable method (for example, a casting method in which a solution obtained by dissolving a resin in water or an organic solvent is cast, a casting method, an extrusion method). . The thickness of the polarizer can be appropriately set according to the purpose and application of the LCD in which the polarizing plate is used, but is typically 5 to 80 μm.

  As a method for producing a polarizer, any appropriate method can be adopted depending on the purpose, materials used, conditions, and the like. Typically, a method is employed in which the polyvinyl alcohol-based resin film is subjected to a series of production steps including swelling, dyeing, crosslinking, stretching, washing with water, and drying steps. In each processing step except the drying step, the treatment is performed by immersing the polyvinyl alcohol-based resin film in a bath containing a solution used in each step. The order, frequency, and presence / absence of each treatment of swelling, dyeing, crosslinking, stretching, washing with water, and drying can be appropriately set according to the purpose, materials used, conditions, and the like. For example, several processes may be performed simultaneously in one process, and a specific process may be omitted. More specifically, for example, the stretching process may be performed after the dyeing process, may be performed before the dyeing process, or may be performed simultaneously with the swelling process, the dyeing process, and the crosslinking process. Further, for example, it can be suitably employed to perform the crosslinking treatment before and after the stretching treatment. Further, for example, the water washing process may be performed after all the processes, or may be performed only after a specific process.

  The swelling step is typically performed by immersing the polyvinyl alcohol resin film in a treatment bath (swelling bath) filled with water. By this treatment, dirt on the surface of the polyvinyl alcohol-based resin film and an anti-blocking agent can be washed, and unevenness such as uneven dyeing can be prevented by swelling the polyvinyl alcohol-based resin film. Glycerin, potassium iodide, or the like can be appropriately added to the swelling bath. The temperature of the swelling bath is typically about 20 to 60 ° C., and the immersion time in the swelling bath is typically about 0.1 to 10 minutes.

  The dyeing step is typically performed by immersing the polyvinyl alcohol-based resin film in a treatment bath (dye bath) containing a dichroic substance such as iodine. As the solvent used for the dye bath solution, water is generally used, but an appropriate amount of an organic solvent compatible with water may be added. The dichroic substance is typically used at a ratio of 0.1 to 1.0 part by weight with respect to 100 parts by weight of the solvent. When iodine is used as the dichroic substance, the dye bath solution preferably further contains an auxiliary agent such as iodide. This is because the dyeing efficiency is improved. The auxiliary is preferably used in a proportion of 0.02 to 20 parts by weight, more preferably 2 to 10 parts by weight, with respect to 100 parts by weight of the solvent. Specific examples of iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and iodide. Titanium is mentioned. The temperature of the dyeing bath is typically about 20 to 70 ° C., and the immersion time in the dyeing bath is typically about 1 to 20 minutes.

  The crosslinking step is typically performed by immersing the dyed polyvinyl alcohol resin film in a treatment bath (crosslinking bath) containing a crosslinking agent. Arbitrary appropriate crosslinking agents can be employ | adopted as a crosslinking agent. Specific examples of the crosslinking agent include boron compounds such as boric acid and borax, glyoxal, and glutaraldehyde. These can be used alone or in combination. As the solvent used for the solution of the crosslinking bath, water is generally used, but an appropriate amount of an organic solvent having compatibility with water may be added. The crosslinking agent is typically used at a ratio of 1 to 10 parts by weight with respect to 100 parts by weight of the solvent. When the concentration of the crosslinking agent is less than 1 part by weight, sufficient optical properties cannot often be obtained. When the concentration of the crosslinking agent exceeds 10 parts by weight, the stretching force generated in the film during stretching increases, and the resulting polarizing plate may shrink. The solution of the crosslinking bath preferably further contains an auxiliary agent such as iodide. This is because it is easy to obtain uniform characteristics in the plane. The concentration of the auxiliary agent is preferably 0.05 to 15% by weight, more preferably 0.5 to 8% by weight. Specific examples of iodide are the same as those in the dyeing process. The temperature of the crosslinking bath is typically about 20 to 70 ° C, preferably 40 to 60 ° C. The immersion time in the crosslinking bath is typically about 1 second to 15 minutes, preferably 5 seconds to 10 minutes.

  The stretching process may be performed at any stage as described above. Specifically, it may be performed after the dyeing process, may be performed before the dyeing process, may be performed simultaneously with the swelling process, the dyeing process, and the crosslinking process, or may be performed after the crosslinking process. The cumulative draw ratio of the polyvinyl alcohol-based resin film needs to be 5 times or more, preferably 5 to 7 times, and more preferably 5 to 6.5 times. When the cumulative draw ratio is less than 5 times, it may be difficult to obtain a polarizing plate with a high degree of polarization. When the cumulative draw ratio exceeds 7 times, the polyvinyl alcohol-based resin film (polarizer) may be easily broken. Arbitrary appropriate methods may be employ | adopted as a specific method of extending | stretching. For example, when the wet stretching method is adopted, the polyvinyl alcohol-based resin film is stretched at a predetermined magnification in a treatment bath (stretching bath). As the stretching bath solution, a solution in which various metal salts, iodine, boron or zinc compounds are added to a solvent such as water or an organic solvent (for example, ethanol) is preferably used.

  The water washing step is typically performed by immersing the polyvinyl alcohol-based resin film subjected to the above-described various treatments in a treatment bath (water washing bath). An unnecessary residue of the polyvinyl alcohol-based resin film can be washed away by the water washing step. The washing bath may be pure water or an aqueous solution of iodide (for example, potassium iodide or sodium iodide). The concentration of the iodide aqueous solution is preferably 0.1 to 10% by mass. An auxiliary agent such as zinc sulfate or zinc chloride may be added to the aqueous iodide solution. The temperature of the washing bath is preferably 10 to 60 ° C, more preferably 30 to 40 ° C. The immersion time is typically 1 second to 1 minute. The water washing step may be performed only once, or may be performed a plurality of times as necessary. When implemented several times, the kind and density | concentration of the additive contained in the washing bath used for each process can be adjusted suitably. For example, the water washing step includes a step of immersing the polymer film in an aqueous potassium iodide solution (0.1 to 10% by mass, 10 to 60 ° C.) for 1 second to 1 minute, and a step of rinsing with pure water.

  Any appropriate drying method (for example, natural drying, air drying, heat drying) may be employed as the drying step. For example, in the case of heat drying, the drying temperature is typically 20 to 80 ° C., and the drying time is typically 1 to 10 minutes. A polarizer is obtained as described above.

  In the polarizing plate of this invention, although the said polarizer and the optical film of this invention are included, it is preferable to have an easily bonding layer and an adhesive bond layer between an optical film and a polarizer.

  The adhesive layer is preferably a layer formed from a polyvinyl alcohol-based adhesive. The polyvinyl alcohol-based adhesive contains a polyvinyl alcohol-based resin and a crosslinking agent.

  The polyvinyl alcohol-based resin is not particularly limited. For example, polyvinyl alcohol obtained by saponifying polyvinyl acetate; a derivative thereof; and a saponified product of a copolymer with a monomer having copolymerizability with vinyl acetate. Modified polyvinyl alcohol obtained by acetalization, urethanization, etherification, grafting, phosphoric esterification, etc. of polyvinyl alcohol. Examples of the monomer include unsaturated carboxylic acids such as (anhydrous) maleic acid, fumaric acid, crotonic acid, itaconic acid, (meth) acrylic acid, and esters thereof; α-olefins such as ethylene and propylene, (meth) Examples include allyl sulfonic acid (soda), sulfonic acid soda (monoalkyl malate), disulfonic acid soda alkyl maleate, N-methylol acrylamide, acrylamide alkyl sulfonic acid alkali salt, N-vinyl pyrrolidone, N-vinyl pyrrolidone derivatives, and the like. . These polyvinyl alcohol resins may be used alone or in combination of two or more.

  From the viewpoint of adhesiveness, the polyvinyl alcohol-based resin preferably has an average degree of polymerization of 100 to 3000, more preferably 500 to 3000, and an average degree of saponification of preferably 85 to 100 mol%, more preferably 90. ˜100 mol%.

  As the polyvinyl alcohol resin, a polyvinyl alcohol resin having an acetoacetyl group can be used. A polyvinyl alcohol-based resin having an acetoacetyl group is a polyvinyl alcohol-based adhesive having a highly reactive functional group, and is preferable in terms of improving the durability of the polarizing plate.

  A polyvinyl alcohol-based resin containing an acetoacetyl group is obtained by reacting a polyvinyl alcohol-based resin with diketene by a known method. For example, a method in which a polyvinyl alcohol resin is dispersed in a solvent such as acetic acid and diketene is added thereto, and a polyvinyl alcohol resin is previously dissolved in a solvent such as dimethylformamide or dioxane, and diketene is added thereto. And the like. Moreover, the method of making diketene gas or liquid diketene contact directly to polyvinyl alcohol is mentioned.

  The degree of acetoacetyl group modification of the polyvinyl alcohol resin having an acetoacetyl group is not particularly limited as long as it is 0.1 mol% or more. If it is less than 0.1 mol%, the water resistance of the adhesive layer is insufficient, which is inappropriate. The degree of acetoacetyl modification is preferably 0.1 to 40 mol%, more preferably 1 to 20 mol%. When the degree of acetoacetyl modification exceeds 40 mol%, the number of reaction points with the cross-linking agent decreases, and the effect of improving water resistance is small. The degree of acetoacetyl modification is a value measured by NMR.

As said crosslinking agent, what is used for the polyvinyl alcohol-type adhesive agent can be especially used without a restriction | limiting.
As the crosslinking agent, a compound having at least two functional groups having reactivity with the polyvinyl alcohol resin can be used. For example, alkylene diamines having two alkylene groups and two amino groups such as ethylene diamine, triethylene amine, hexamethylene diamine (hexamethylene diamine is preferred); tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylene propane tolylene Isocyanate adduct, triphenylmethane triisocyanate, methylene bis (4-phenylmethane triisocyanate, isophorone diisocyanate and isocyanates such as ketoxime block or phenol block; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin di Or triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylo Epoxys such as rupropane triglycidyl ether, diglycidyl aniline, diglycidyl amine; monoaldehydes such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde; glyoxal, malondialdehyde, succindialdehyde, glutardialdehyde, maleidialdehyde , Dialdehydes such as phthaldialdehyde; amino-formaldehyde resins such as methylol urea, methylol melamine, alkylated methylol urea, alkylated methylolated melamine, acetoguanamine, condensates of benzoguanamine and formaldehyde; sodium, potassium, magnesium Divalent metals such as calcium, aluminum, iron and nickel, or salts of trivalent metals and oxides thereof. Is to, melamine-based crosslinking agent is preferably, suitable in particular melamine.

  The amount of the crosslinking agent is preferably 0.1 to 35 parts by weight, more preferably 10 to 25 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol resin. On the other hand, in order to further improve the durability, the crosslinking agent can be blended in a range of more than 30 parts by weight and 46 parts by weight or less with respect to 100 parts by weight of the polyvinyl alcohol resin. In particular, when a polyvinyl alcohol-based resin containing an acetoacetyl group is used, it is preferable to use the crosslinking agent in an amount exceeding 30 parts by weight. Water resistance improves by mix | blending a crosslinking agent in the range of more than 30 weight part and 46 weight part or less.

  The polyvinyl alcohol-based adhesive further includes coupling agents such as silane coupling agents and titanium coupling agents, various tackifiers, ultraviolet absorbers, antioxidants, heat stabilizers, hydrolysis stabilizers, and the like. A stabilizer or the like can also be blended.

  The optical film of the present invention can be subjected to an easy adhesion treatment for improving adhesion on the surface in contact with the polarizer. Examples of the easy adhesion treatment include surface treatment such as corona treatment, plasma treatment, low-pressure UV treatment, and saponification treatment, and it is preferable to form an easy adhesion layer (anchor layer) after performing the easy adhesion treatment.

  In the polarizing plate of this invention, the outstanding effect that favorable adhesiveness of a polarizer and an optical film is realizable can be exhibited, maintaining high heat resistance, high transparency, and high mechanical strength.

  As said easily bonding layer, the silicone layer which has a reactive functional group is mentioned, for example. The material of the silicone layer having a reactive functional group is not particularly limited. For example, an isocyanate group-containing alkoxysilanol, an amino group-containing alkoxysilanol, a mercapto group-containing alkoxysilanol, a carboxy-containing alkoxysilanol, an epoxy group-containing Examples thereof include alkoxysilanols, vinyl-type unsaturated group-containing alkoxysilanols, halogen group-containing alkoxylanols, and isocyanate group-containing alkoxysilanols, and amino silanols are preferred. Furthermore, the adhesive force can be strengthened by adding a titanium-based catalyst or a tin-based catalyst for efficiently reacting the silanol. Moreover, you may add another additive to the silicone which has the said reactive functional group. Specifically, terpene resins, phenol resins, terpene-phenol resins, rosin resins, xylene resins and other tackifiers, UV absorbers, antioxidants, heat stabilizers and other stabilizers may be used.

  The silicone layer having the reactive functional group is formed by coating and drying by a known technique. The thickness of the silicone layer is preferably 1 to 100 nm, more preferably 10 to 50 nm after drying. During coating, silicone having a reactive functional group may be diluted with a solvent. The dilution solvent is not particularly limited, and examples thereof include alcohols. The dilution concentration is not particularly limited, but is preferably 1 to 5% by weight, more preferably 1 to 3% by weight.

  The adhesive layer is formed by applying the adhesive to either side or both sides of the optical film and to either side or both sides of the polarizer. After laminating the optical film and the polarizer, a drying step is performed to form an adhesive layer composed of a coating dry layer. This can also be bonded after forming the adhesive layer. Bonding of the polarizer and the optical film can be performed by a roll laminator or the like. The heating and drying temperature and drying time are appropriately determined according to the type of adhesive.

  The thickness of the adhesive layer is preferably 0.01 to 10 μm, more preferably 0.03 to 5 μm, because it is not preferable in terms of the adhesiveness of the optical film if the thickness after drying becomes too thick.

  The optical film can be bonded to the polarizer by adhering to both sides of the polarizer on one side of the optical film.

  In addition, the optical film can be bonded to the polarizer by adhering to one side of the polarizer on one side of the optical film and bonding the cellulosic resin film to the other side.

  The cellulose resin film is not particularly limited, but triacetyl cellulose is preferable in terms of transparency and adhesiveness. The thickness of the cellulose resin film is preferably 30 to 100 μm, more preferably 40 to 80 μm. If the thickness is less than 30 μm, the film strength is lowered and workability is inferior.

  The polarizing plate of the present invention may have an adhesive layer as at least one of the outermost layers (such a polarizing plate may be referred to as an adhesive polarizing plate). As a particularly preferred embodiment, a pressure-sensitive adhesive layer for adhering to other members such as other optical films and liquid crystal cells can be provided on the side of the optical film where the polarizer is not adhered.

  The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited. For example, an acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer is used as a base polymer. It can select suitably and can be used. In particular, those having excellent optical transparency such as an acrylic pressure-sensitive adhesive, exhibiting appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and being excellent in weather resistance and heat resistance can be preferably used. In particular, an acrylic pressure-sensitive adhesive made of an acrylic polymer having 4 to 12 carbon atoms is preferable.

  In addition to the above, in terms of prevention of foaming and peeling phenomena due to moisture absorption, deterioration of optical properties and liquid crystal cell warpage due to differences in thermal expansion, etc., as well as formability of liquid crystal display devices with high quality and excellent durability An adhesive layer having a low moisture absorption rate and excellent heat resistance is preferred.

  The pressure-sensitive adhesive layer is, for example, a natural or synthetic resin, in particular, a tackifier resin, a filler or pigment made of glass fiber, glass beads, metal powder, other inorganic powders, a colorant, an antioxidant. An additive to be added to the pressure-sensitive adhesive layer such as an agent may be contained.

  Moreover, the adhesive layer etc. which contain microparticles | fine-particles and show light diffusibility may be sufficient.

  The attachment of the pressure-sensitive adhesive layer can be performed by an appropriate method. For example, a pressure sensitive adhesive solution of about 10 to 40% by weight in which a base polymer or a composition thereof is dissolved or dispersed in a solvent composed of a suitable solvent alone or a mixture such as toluene and ethyl acetate is prepared. A method in which it is attached directly on the polarizing plate or the optical film by an appropriate development method such as a casting method or a coating method, or an adhesive layer is formed on the separator in accordance with the above and transferred to the optical film surface. The method of wearing is raised.

  The pressure-sensitive adhesive layer can be provided on one side or both sides of the polarizing plate as a superposed layer of different compositions or types. Moreover, when providing in both surfaces, it can also be set as adhesive layers with a different composition, a kind, thickness, etc. in the front and back of a polarizing plate.

  The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the purpose of use and adhesive force, and is preferably 1 to 40 μm, more preferably 5 to 30 μm, and particularly preferably 10 to 25 μm. When the thickness is less than 1 μm, the durability is deteriorated. When the thickness is more than 40 μm, floating or peeling due to foaming or the like is liable to occur, resulting in poor appearance.

  In order to improve the adhesion between the optical film and the pressure-sensitive adhesive layer, an anchor layer may be provided between the layers.

  As the anchor layer, an anchor layer selected from polyurethane, polyester and polymers containing an amino group in the molecule is preferably used, and polymers containing an amino group in the molecule are particularly preferably used. Polymers containing amino groups in the molecule are good because the amino groups in the molecule exhibit interactions such as reaction or ionic interaction with carboxyl groups in the adhesive and polar groups in the conductive polymer. Adhesion is ensured.

  Examples of the polymer containing an amino group in the molecule include, for example, polyethyleneimine, polyallylamine, polyvinylamine, polyvinylpyridine, polyvinylpyrrolidine, and amino-containing groups such as dimethylaminoethyl acrylate shown as a copolymerization monomer of the above-mentioned acrylic adhesive. Examples thereof include polymers of contained monomers.

  In order to impart antistatic properties to the anchor layer, an antistatic agent may be added. Antistatic agents for imparting antistatic properties include ionic surfactant systems, conductive polymer systems such as polyaniline, polythiophene, polypyrrole, and polyquinoxaline, and metal oxide systems such as tin oxide, antimony oxide, and indium oxide. In particular, a conductive polymer system is preferably used from the viewpoint of optical characteristics, appearance, antistatic effect, and stability of the antistatic effect when heated and humidified. Among these, water-soluble conductive polymers such as polyaniline and polythiophene or water-dispersible conductive polymers are particularly preferably used. This is because, when a water-soluble conductive polymer or a water-dispersible conductive polymer is used as a material for forming the antistatic layer, it is possible to suppress deterioration of the optical film substrate due to an organic solvent during the coating process.

  In the present invention, the polarizer, the optical film, etc. that form the polarizing plate described above, and each layer such as the pressure-sensitive adhesive layer include, for example, salicylic acid ester compounds, benzophenol compounds, benzotriazole compounds, cyanoacrylate compounds, Those having an ultraviolet absorbing ability by a method such as a method of treating with an ultraviolet absorber such as a nickel complex compound may be used.

  The polarizing plate of the present invention may be provided on either the viewing side or the backlight side of the liquid crystal cell or on both sides, and is not limited.

(Image display device)
Next, the image display apparatus of the present invention will be described. The image display device of the present invention includes at least one polarizing plate of the present invention. Here, a liquid crystal display device will be described as an example, but it goes without saying that the present invention can be applied to any display device that requires a polarizing plate. Specific examples of the image display device to which the polarizing plate of the present invention can be applied include a self-luminous display device such as an electroluminescence (EL) display, a plasma display (PD), and a field emission display (FED: Field Emission Display). Can be mentioned. FIG. 2 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention. In the illustrated example, a transmissive liquid crystal display device will be described, but it goes without saying that the present invention is also applied to a reflective liquid crystal display device and the like.

  The liquid crystal display device 100 includes a liquid crystal cell 10, retardation films 20 and 20 ′ disposed across the liquid crystal cell 10, and polarizing plates 30 and 30 ′ disposed outside the retardation films 20 and 20 ′. A light guide plate 40, a light source 50, and a reflector 60 are provided. The polarizing plates 30 and 30 'are arranged so that their polarization axes are orthogonal to each other. The liquid crystal cell 10 includes a pair of glass substrates 11 and 11 ′ and a liquid crystal layer 12 as a display medium disposed between the substrates. One substrate 11 is provided with a switching element (typically a TFT) for controlling the electro-optical characteristics of the liquid crystal, a scanning line for supplying a gate signal to the switching element, and a signal line for supplying a source signal ( Neither is shown). The other glass substrate 11 ′ is provided with a color layer constituting a color filter and a light shielding layer (black matrix layer) (both not shown). The distance (cell gap) between the substrates 11 and 11 ′ is controlled by the spacer 13. In the liquid crystal display device of the present invention, the polarizing plate of the present invention described above is employed as at least one of the polarizing plates 30 and 30 '.

  For example, in the case of the TN mode, in such a liquid crystal display device 100, when no voltage is applied, the liquid crystal molecules of the liquid crystal layer 12 are arranged in a state where the polarization axis is shifted by 90 degrees. In such a state, incident light that is transmitted through only light in one direction by the polarizing plate is twisted 90 degrees by liquid crystal molecules. As described above, since the polarizing plates are arranged so that the polarization axes thereof are orthogonal to each other, the light (polarized light) reaching the other polarizing plate is transmitted through the polarizing plate. Therefore, when no voltage is applied, the liquid crystal display device 100 performs white display (normally white method). On the other hand, when a voltage is applied to such a liquid crystal display device 100, the arrangement of liquid crystal molecules in the liquid crystal layer 12 changes. As a result, the light (polarized light) that has reached the other polarizing plate cannot be transmitted through the polarizing plate, resulting in black display. An image is formed by switching such display for each pixel using an active element.

  EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited to these Examples. Unless otherwise indicated, parts and percentages in the examples are based on weight.

<Adhesion between optical film and polarizer>
The state when the polarizing plate (100 mm × 100 mm) was twisted by hand and threaded was evaluated according to the following criteria.
○: The polarizer and the optical film are integrated and peeling does not occur.
(Triangle | delta): Peeling is recognized by a polarizer, an optical film, and an edge part.
X: Peeling is recognized between the polarizer and the optical film.

[Production Example 1: Production of polarizer]
A polyvinyl alcohol film having a thickness of 80 μm was dyed in an aqueous iodine solution of 5% by weight (weight ratio: iodine / potassium iodide = 1/10). Next, after being immersed in an aqueous solution containing 3% by weight boric acid and 2% by weight potassium iodide and further stretched to 5.5 times in an aqueous solution containing 4% by weight boric acid and 3% by weight potassium iodide. It was immersed in a 5% by weight aqueous potassium iodide solution. Then, it dried for 3 minutes in 40 degreeC oven, and obtained the 30-micrometer-thick polarizer.

[Production Example 2: Production of lactone ring-containing acrylic resin (1A)]
A lactone ring-containing acrylic resin (1A) was produced according to the method described in Production Example 1 of JP-A-2006-171464. That is, 8000 g of methyl methacrylate (MMA), 2000 g of methyl 2- (hydroxymethyl) methyl acrylate (MHMA), 10000 g of 4- Methyl-2-pentanone (methyl isobutyl ketone, MIBK) and 5.0 g of n-dodecyl mercaptan were charged, and the temperature was raised to 105 ° C. through nitrogen, and when refluxed, 5.0 g of tertiary butyl was used as an initiator. While adding peroxyisopropyl carbonate (made by Kayaku Akzo, trade name: Kaya-Carbon BIC-75), simultaneously adding 10.0 g of tertiary butyl peroxyisopropyl carbonate and 230 g of MIBK dropwise over 2 hours, Solution polymerization under reflux (about 105-120 ° C) Done, aging was carried out over an additional 4 hours.

  To the obtained polymer solution, 30 g of stearyl phosphate / distearyl phosphate mixture (manufactured by Sakai Chemicals, trade name: Phoslex A-18) was added and cyclized under reflux (about 90 to 120 ° C.) for 5 hours. A condensation reaction was performed. Subsequently, the polymer solution obtained by the cyclization condensation reaction was subjected to a vent having a barrel temperature of 260 ° C., a rotation speed of 100 rpm, a degree of vacuum of 13.3 to 400 hPa (10 to 300 mmHg), a rear vent number of 1, and a forevent number of 4 It is introduced into a type screw twin screw extruder (Φ = 29.75 mm, L / D = 30) at a processing rate of 2.0 kg / hour in terms of resin amount, and cyclization condensation reaction and devolatilization are carried out in the extruder. By extrusion, a transparent lactone ring-containing acrylic resin pellet (1A) was obtained.

[Example 1]
(Production of optical film)
100 parts of lactone ring-containing acrylic resin pellets (1A), Staphyloid IM-702 (core-shell type nanoparticles, core layer is rubbery polymer, shell layer is glassy polymer) manufactured by Ganz Kasei Co., Ltd. 30 The parts were mixed and extruded from a T die at a die temperature of 260 ° C. using a single screw extruder to obtain an optical film (1) of 120 μm. The primary particle size of Staphyloid IM-702 was 200 nm, and the aggregate particle size was 200 nm to 2 mm. Dxy of the obtained optical film (1) was 1.089, which was larger than 1 and exhibited parallel dichroism. Dxz of the obtained optical film (1) was 1.56, which was larger than 1 and indicated that the film was oriented out of plane.

(Formation of easy adhesion layer)
A solution prepared by adding 66.7 parts of isopropyl alcohol to 100 parts of silane coupling agent APZ-6601 (manufactured by Toray Dow Corning Silicone Co., Ltd.) on one side of the optical film (1) obtained above. Corona treatment was performed at a discharge amount of 70 w · min / m ² , and the corona treatment surface was coated with a wire bar # 5 to evaporate volatile components.

(Preparation of adhesive aqueous solution)
A polyvinyl alcohol adhesive aqueous solution prepared by adjusting an aqueous solution containing 20 parts by weight of methylolmelamine to 100 parts by weight of an acetoacetyl-modified polyvinyl alcohol resin (degree of acetylation 13%) to a concentration of 0.5% by weight Prepared.

(Preparation of polarizing plate)
Triacetylcellulose (manufactured by Fuji Photo Film Co., Ltd., trade name: T-40UZ) in which the easy-adhesion layer surface of the optical film (1) is applied to one side of the polarizer produced in Production Example 1 and the other surface is saponified. Were bonded using the polyvinyl alcohol-based adhesive aqueous solution prepared above. The polyvinyl alcohol adhesive aqueous solution was applied to the easy-adhesion layer side and the triacetyl cellulose side of the optical film (1), respectively, and dried at 70 ° C. for 10 minutes to obtain a polarizing plate (1).

(Formation of adhesive layer)
As a base polymer, a solution (solid content 30) containing an acrylic polymer having a weight average molecular weight of 2 million consisting of a copolymer of butyl acrylate: acrylic acid: 2-hydroxyethyl acrylate = 100: 5: 0.1 (weight ratio) %) Was used. Viscosity adjustment of 4 parts of Coronate L manufactured by Nippon Polyurethane Co., Ltd., which is an isocyanate-based polyfunctional compound, to 100 parts of polymer solids and 0.5 part of an additive (KBM403, manufactured by Shin-Etsu Silicone) A solvent (ethyl acetate) was added to prepare an adhesive solution (solid content 12%). The pressure-sensitive adhesive solution was applied on a release film (polyethylene terephthalate substrate: Diafoil MRF38, manufactured by Mitsubishi Chemical Polyester) so that the thickness after drying was 25 μm, and then dried in a hot air circulation oven, An adhesive layer was formed.

(Polarizing plate anchor layer)
A polyethylenimine adduct of polyacrylic acid ester (trade name: Polyment NK380, manufactured by Nippon Shokubai Co., Ltd.) was diluted 50 times with methyl isobutyl ketone. This was coated and dried on one side of the polarizing plate using a wire bar (# 5) so that the thickness after drying was 50 nm.

(Preparation of adhesive polarizing plate)
A release film on which the pressure-sensitive adhesive layer was formed was bonded to the anchor layer of the polarizing plate to produce a pressure-sensitive adhesive-type polarizing plate (1).

(Evaluation of polarizing plate)
The adhesive property between the optical film (1) and the polarizer in the obtained polarizing plate was evaluated. The results are shown in Table 1.

[Example 2]
In the production of the optical film of Example 1, a film obtained by extrusion from a T-die was stretched 2.0 times at 140 ° C. in the longitudinal direction, and then stretched 2.0 times at 140 ° C. in the transverse direction to obtain a thickness of 60 μm. Except having obtained this film, it carried out similarly to Example 1, and obtained the optical film (2), the polarizing plate (2), and the adhesive type polarizing plate (2).

  Dxy of the obtained optical film (2) was 1.088, which was larger than 1 and exhibited parallel dichroism. Dxz of the obtained optical film (2) was 1.99, which was larger than 1 and indicated that the film was oriented out of plane. Furthermore, the adhesiveness of the optical film (2) and polarizer in the obtained polarizing plate was evaluated. The results are shown in Table 1.

[Comparative Example 1]
The production of the optical film of Example 2 was performed in the same manner as in Example 2 except that Staphyloid IM-702 was not used, and the optical film (3), the polarizing plate (3), and the adhesive-type polarizing plate (3) were formed. Obtained.

  Dxy of the obtained optical film (3) was 0.899, smaller than 1, Dxz was 1.00, and did not show out-of-plane orientation. Furthermore, the adhesiveness of the optical film (3) and polarizer in the obtained polarizing plate was evaluated. The results are shown in Table 1.

表１に示すように、実施例１および実施例２では、貼り合わせ品の接着性に優れた光学フィルムが得られたが、比較例１では、貼り合わせ品の接着性に劣る光学フィルムしか得られなかった。

As shown in Table 1, in Examples 1 and 2, an optical film excellent in the adhesiveness of the bonded product was obtained, but in Comparative Example 1, only an optical film inferior in the adhesiveness of the bonded product was obtained. I couldn't.

  The optical film and polarizing plate of the present invention can be suitably used for various image display devices (liquid crystal display devices, organic EL display devices, PDPs, etc.).

It is sectional drawing which shows an example of the polarizing plate of this invention. 1 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Liquid crystal cell 11, 11 'Glass substrate 12 Liquid crystal layer 13 Spacer 20, 20' Retardation film 30, 30 'Polarizing plate 31 Polarizer 32 Adhesive layer 33 Easy-adhesion layer 34 Optical film 35 Adhesive layer 36 Polarizer protective film 40 Light guide plate 50 Light source 60 Reflector 100 Liquid crystal display device

Claims (6)

It is an acrylic film in which core-shell nanoparticles are blended with the resin constituting the film,
The resin constituting the film contains 90% by weight or more of a lactone ring-containing acrylic resin with respect to the total amount of the resin ,
The compounding amount of the core-shell type nanoparticles is 10 to 40% by weight based on the total amount of the resin constituting the film,
The core-shell type nanoparticles have a core layer made of a rubbery polymer and a shell layer made of a glassy polymer,
The core-shell nanoparticle has a particle size of 100 to 700 nm,
An optical film in which at least one surface is oriented out of plane and a Dxz of 1240 cm ⁻¹ in a polarized ATR / FT-IR spectrum measured at an incident angle of 60 degrees is 1.05 or more. The optical film according to claim 1, wherein a Dxy of 1240 cm ⁻¹ in a polarized ATR / FT-IR spectrum measured at an incident angle of 60 degrees is 1.00 or more.   The optical film according to claim 1, wherein the out-of-plane orientation is formed by a chemical orientation treatment.   The optical film according to any one of claims 1 to 3, which is a polarizer protective film.   A polarizing plate comprising a polarizer formed from a polyvinyl alcohol-based resin and the optical film according to claim 4.   An image display device comprising at least one polarizing plate according to claim 5.

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