TWI647492B - Optical laminate and graphic display device - Google Patents

Abstract

The present invention provides an optical laminate, and an image display device using the optical laminate. The optical layered body provided by the present invention comprises a polarizer and an optical film laminated on one side of the polarizer, wherein the optical film is converted by linearly polarized light into a circularly polarized light and is emitted, and satisfies the following formula: (1) 100 nm ≦R _e (590)≦180nm, (2)0.5<R _th (590)/R _e (590)≦0.8, (3)0.85≦R _e (450)/R _e (550)<1.00, and (4 1.00 < R _e (630) / R _e (550) ≦ 1.1 [wherein, R _e (590), R _e (450), R _e (550), and R _e (630) are expressed at the measurement wavelength 590, The in-plane retardation value in 450, 550, and 630 nm, and R _th (590) is the thickness direction retardation value in the measurement wavelength of 590 nm. ].

Description

Optical laminate and image display device

The present invention relates to an optical layered body comprising a polarizer, and an image display device using the optical layered body.

The image display device represented by a liquid crystal display device is mounted on a mobile device such as a mobile phone, a smart phone, a tablet type information terminal, a mobile TV, a digital camera, and a car guide. For example, when such a mobile device is used outside the house, the screen of the image display device may be recognized while wearing the polarized sunglasses. In this case, the image display device requires the screen to be viewed through the polarized sunglasses. The recognition is still excellent.

Several proposals have been made in the past (Patent Documents 1 to 10) in order to improve the visibility of the screen when viewed through polarized sunglasses.

(previous technical literature) (Patent Literature)

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2009-122454

[Patent Document 2] Japanese Patent Laid-Open Publication No. 2011-107198

[Patent Document 3] Japanese Laid-Open Patent Publication No. 2011-215646

[Patent Document 4] Japanese Laid-Open Patent Publication No. 2012-230390

[Patent Document 5] Japanese Patent Laid-Open Publication No. 03-174512

[Patent Document 6] Japanese Patent Laid-Open Publication No. 2013-231761

[Patent Document 7] Japanese Laid-Open Patent Publication No. 2011-113018

[Patent Document 8] Japanese Patent Laid-Open Publication No. 2013-182162

[Patent Document 9] Japanese Patent Laid-Open Publication No. 2013-200445

[Patent Document 10] Japanese Patent Laid-Open Publication No. 2010-091655

The conventional method for improving the visibility when viewing a screen through polarized sunglasses can be roughly divided into: a linear polarized light that is emitted from a polarizing plate disposed on the identification side of an image display element such as a liquid crystal element. a circular (or circular) polarized phase difference plate (for example, a λ/4 wavelength plate) disposed on the identification side of the polarizing plate (Patent Documents 1 to 9); and, for converting the linearly polarized light into none A method in which the polarized depolarization layer is disposed on the identification side of the polarizing plate (Patent Document 10).

However, any of the above-mentioned methods proposed by the prior art is related to the absorption axis of the polarizing plate disposed on the side of the image display element and the polarizing sunglasses in order to suppress the brightness of the screen when viewed through the polarized sunglasses. The technique of changing the angle formed by the absorption axis is not a technique for suppressing the change in color tone when viewing a picture from various directions (azimuth and polar angle).

It is an object of the present invention to provide for the transmission of polarized light The optical layered body of the image display device in which the change in the color tone of the sun glasses is small in various directions (azimuth and polar angle), and the image display device having good visibility using the optical layered body.

The present invention provides the following optical layered body and image display device.

[1] An optical layered body comprising: a polarizer; and an optical film laminated on one surface of the polarizer, wherein the optical film is formed by converting linearly polarized light into rounded polarized light, and satisfies the following formula: (1) 100 nm ≦R _e (590) ≦ 180 nm, (2) 0.5 < R _th (590) / R _e (590) ≦ 0.8, (3) 0.85 ≦ R _e (450) / R _e (550) < 1.00 And (4) 1.00 < R _e (630) / R _e (550) ≦ 1.1 [wherein, R _e (590), R _e (450), R _e (550), and R _e (630) are respectively In the in-plane retardation value at the measurement wavelengths of 590 nm, 450 nm, 550 nm, and 630 nm, R _th (590) is a thickness direction phase difference value expressed in the measurement wavelength of 590 nm. ].

[2] The optical layered product according to [1], wherein an angle formed by a slow axis of the optical film and an absorption axis of the polarizer is 45 ± 20° or 135 ± 20°.

[3] The optical layered product according to the above [1], wherein the optical film contains a cyclic polyolefin resin, a polycarbonate resin, a cellulose resin, a polyester resin, or (meth)acrylic Resin.

[4] The optical layered product according to any one of [1] to [3] wherein the optical film is laminated on the polarizer via a first adhesive layer or an adhesive layer.

[5] The optical layered product according to any one of [1] to [4] further comprising a second adhesive layer laminated on a surface of the polarizer opposite to the optical film.

[6] The optical layered product according to any one of [1] to [4] further comprising a thermoplastic resin film laminated on a surface of the polarizer opposite to the optical film.

[7] The optical layered product according to [6], wherein the thermoplastic resin film is a retardation film.

[8] The optical laminate according to [6] or [7], further comprising a third adhesive layer laminated on a surface of the thermoplastic resin film opposite to the polarizer.

[9] The image display device according to any one of [1] to [8] wherein the optical layered body is such that the polarizer is on the image display element side. Configured in a way.

According to the present invention, it is possible to provide an optical layered body of an image display device which can realize a change in color tone when a screen is seen through various directions (azimuth and polar angle) through polarized sunglasses, and an image display device using the optical layered body. .

1, 2, 3, 4, 5‧ ‧ optical laminates

10‧‧‧ polarizer

10a‧‧‧Absorption axis of polarizer

20‧‧‧Optical film

20a‧‧‧The slow phase axis of the optical film

25‧‧‧1st adhesive layer or adhesive layer

30‧‧‧2nd adhesive layer

40‧‧‧1st thermoplastic resin film

45‧‧‧4th adhesive layer or adhesive layer

50‧‧‧3rd adhesive layer

60‧‧‧2nd thermoplastic resin film

65‧‧‧ adhesive layer

70‧‧‧Liquid crystal components

80‧‧‧Polar plate

80a‧‧‧Absorption axis of polarizing plate

85‧‧‧Adhesive layer

90‧‧‧ Backlight

100‧‧‧Light source

110‧‧‧ glass plate

120‧‧‧Polarized film

120a‧‧‧Absorption axis of polarizing film

130‧‧‧Receiver Department (camera)

Fig. 1 is a schematic cross-sectional view showing an example of a layer structure of an optical layered body according to the present invention.

Fig. 2 is a schematic cross-sectional view showing another example of the layer structure of the optical layered body according to the present invention.

Fig. 3 is a schematic cross-sectional view showing another example of the layer structure of the optical layered body according to the present invention.

Fig. 4 is a schematic cross-sectional view showing another example of the layer structure of the optical layered body according to the present invention.

Fig. 5 (a) and (b) are diagrams for explaining an azimuth angle and a polar angle indicating directions of a screen of the image display device.

Fig. 6 (a) and (b) are views for explaining the formation angle θ of the slow axis of the optical film and the absorption axis of the polarizer.

Fig. 7 is a schematic cross-sectional view showing the layer structure of a liquid crystal display device of the present invention.

Fig. 8 (a) and (b) schematically show a side view and an exploded perspective view of a measurement system for changing the color tone.

Fig. 9 is an xy chromaticity diagram obtained from the optical layered body of Example 1.

Fig. 10 is an xy chromaticity diagram obtained from the optical layered body of Example 2.

Fig. 11 is an xy chromaticity diagram obtained from the optical layered body of Example 3.

Fig. 12 is an xy chromaticity diagram obtained from the optical layered body of Comparative Example 1.

Fig. 13 is an xy chromaticity diagram obtained from the optical laminate of Comparative Example 2.

Fig. 14 is an xy chromaticity diagram obtained from the optical laminate of Comparative Example 3.

Fig. 15 is an xy chromaticity diagram obtained from the optical laminate of Comparative Example 4.

Fig. 16 is an xy chromaticity diagram obtained from the optical laminate of Comparative Example 5.

Fig. 17 is an xy chromaticity diagram obtained from the optical laminate of Comparative Example 6.

[Best Mode for Carrying Out the Invention]

Hereinafter, the form of the embodiment will be described, and the optical layered body and the image display apparatus according to the present invention will be described in detail.

<Optical laminate>

[a] Layer structure of optical laminate

An optical layering system according to the present invention comprises: a polarizer; and an optical film laminated on one side of the polarizer. An example of the layer structure of the optical layered body of the present invention is shown in Fig. 1. The optical laminate 1 shown in Fig. 1 includes a polarizer 10, and an optical film 20 laminated on one surface of the polarizer 10 via a first adhesive layer or an adhesive layer 25. In the optical laminate of the present invention, the optical film 20 is disposed on the polarizer 10 The optical element on one side has a function of converting the linearly polarized light emitted from the polarizer 10 to the optical film 20 into a circularly polarized light (including a case where circularly polarized light is included).

Unlike the example of Fig. 1, the optical layered body according to the present invention may further include other layers laminated on the surface opposite to the optical film 20 in the polarizer 10. Examples of optical laminates containing other layers are shown in Figs. 2 and 3. The optical laminate 2 shown in Fig. 2 includes a polarizer 10; an optical film 20 laminated on one surface of the polarizer 10 sandwiching the first adhesive layer or the adhesive layer 25; in the polarizer 10 The second adhesive layer 30 is laminated on the surface opposite to the optical film 20.

The optical laminate 3 shown in Fig. 3 includes a polarizer 10; an optical film 20 laminated on one surface of the polarizer 10 via a first adhesive layer or an adhesive layer 25; and a fourth adhesive interposed therebetween. The layer or the adhesive layer 45 is laminated on the first thermoplastic resin film 40 on the surface of the polarizer 10 opposite to the optical film 20; and the surface of the first thermoplastic resin film 40 opposite to the polarizer 10 is laminated. The third adhesive layer 50 on top. The third adhesive layer 50 may be omitted in the optical layered body 3.

The second adhesive layer 30 or the third adhesive layer 50 disposed on the outermost side of the optical laminate can be bonded to the optical laminate, for example, in another optical member such as an image display element.

Further, as in the optical layered body 4 shown in Fig. 4, the second thermoplastic resin film 60 may be interposed between the polarizer 10 and the optical film 20. The second thermoplastic resin film 60 can be bonded to the polarizer 10, for example, via the adhesive layer 65.

[b]Polarizer

The polarizer 10 may be an optical element having a property of absorbing a linearly polarized light having a vibration surface parallel to an optical axis (absorption axis) and polarizing a linear light having a vibration surface perpendicular to the optical axis, and specifically, may be suitably used. In the polyvinyl alcohol-based resin film, a dichroic dye (iodine or a dichroic organic dye) is adsorbed and aligned.

The polyvinyl alcohol-based resin constituting the polarizer 10 can be obtained by saponifying a polyvinyl acetate-based resin. As the polyvinyl acetate-based resin, in addition to the polyvinyl acetate which is a homopolymer of vinyl acetate, a copolymer of vinyl acetate and another monomer copolymerizable therewith can be exemplified. Examples of the other monomer copolymerized in the vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and ammonium (meth) acrylamides. The degree of saponification of the polyvinyl alcohol-based resin is usually about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be further modified. For example, an aldehyde-modified polyvinyl alcohol formaldehyde or a polyvinyl acetal may be used.

In the specification of the present invention, "(meth)acrylyl" means at least one selected from the group consisting of an acryl group and a methacryl group. The same is true when it is called "(meth) propylene oxime".

The degree of polymerization of the polyvinyl alcohol-based resin is usually from about 1,000 to 10,000, preferably from about 1,500 to 5,000. Specifically, as a polyvinyl alcohol-based resin or a dichroic dye, for example, those exemplified in JP-A-2012-159778 can be cited.

The film formed of the above polyvinyl alcohol resin is used as the original film of the polarizer 10 and used. The polyvinyl alcohol-based resin can be formed into a film by a known method. The thickness of the original film made of a polyvinyl alcohol-based resin is, for example, about 1 to 150 μm. If the ease of extension is also taken into consideration, the thickness is preferably 10 μm or more.

The polarizer 10 can be produced, for example, by the following steps: a step of uniaxially stretching a polyvinyl alcohol-based resin film as described above; and dyeing the uniaxially stretched polyvinyl alcohol-based resin film with a dichroic dye a step of adsorbing a coloring dye; a step of treating the polyvinyl alcohol-based resin film of the adsorbed dichroic dye with an aqueous solution of boric acid; a step of washing with water by the aqueous solution of boric acid; and a drying step. The thickness of the polarizer 10 is usually about 2 to 40 μm, preferably about 3 to 30 μm.

The polarizer 10 can be produced, for example, according to the method described in JP-A-2012-159778. In the method described in this document, a polyvinyl alcohol-based resin layer is formed by applying a polyvinyl alcohol-based resin to a base film, instead of using the original film formed of the polyvinyl alcohol-based resin. After the polarizing sheet layer (polarizing sheet 10) is formed by stretching and dyeing, a thermoplastic resin film such as a protective film is bonded.

[c]Optical film

The optical film 20 laminated on one aspect of the polarizer 10 is a film satisfying the following formula.

(1) 100 nm ≦R _e (590) ≦ 180 nm, (2) 0.5 < R _th (590) / R _e (590) ≦ 0.8, (3) 0.85 ≦ R _e (450) / R _e (550) < 1.00 And (4) 1.00 <R _e (630) / R _e (550) ≦ 1.1, where R _e (590), R _e (450), R _e (550), and R _e (630) are respectively expressed in The in-plane retardation values at wavelengths of 590 nm, 450 nm, 550 nm, and 630 nm were measured, and R _th (590) is a thickness direction retardation value at a measurement wavelength of 590 nm. These in-plane phase difference values and thickness direction phase difference values were measured in an environment of a temperature of 23 ° C and a relative humidity of 55%.

The refractive index in the in-plane slow axis direction is set to n _x , the in-plane in-phase axis direction (direction perpendicular to the in-plane slow axis direction) is set to n _y , and the thickness direction refractive index is set to n _z When the thickness of the optical film 20 is set to d, the in-plane phase difference value R _e and the thickness direction phase difference R _th of the optical film 20 are _expressed by the following formula: R _e = (n _{x -} n _y ) × d

R _th =[{(n _x +n _y )/2}-n _z ]×d is defined.

In the case of an optical layered body in which the optical film 20 exhibiting the phase difference characteristics and the wavelength dispersion characteristics of the above formulas (1) to (4) is laminated on one aspect of the polarizer 10, the image display device is used (more) Specifically, in the case where the polarizer 10 is disposed on the side of the image display device as a polarizing plate as in the image display device side, it is possible to maintain the transmitted polarized sunglasses from various directions (azimuth and The polar angle) can effectively suppress the change in color tone when the brightness is seen on the screen, and the visibility of the image display device can be improved. In view of this, in the case where any one or more of the above formulas (1) to (4) are not satisfied, the effect of maintaining the brightness and suppressing the color tone cannot be sufficiently achieved at the same time.

As shown in Fig. 5(a), the azimuth angle refers to an angle equivalent to the longitude, and the polar angle refers to an angle corresponding to the latitude. Fig. 5(b) shows an example of the identification position (the position of the eye) when the azimuth angle is 0° and the polar angle is 40°.

From the viewpoint of maintaining the brightness of the screen when viewed through polarized sunglasses, R _e (590) in the formula (1) is preferably from 105 to 170 nm, and from the viewpoint of more effectively suppressing the change in color tone, 2) The middle R _th (590) / R _e (590) is preferably 0.75 or less, and R _e (450) / R _e (550) in the formula (3) is preferably 0.86 to 0.98, in the formula (4) R _e (630)/R _e (550) is preferably 1.01 to 1.06.

The optical film 20 is a type of retardation film which has a function of converting a linearly polarized light emitted from the polarizer 10 to the optical film 20 into a circularly polarized light (including a case where it is a circularly polarized light), and exhibits a function of the sixth retardation film. The optical film 20 of the drawing is laminated on the polarizer 10 such that the retardation axis 20a and the absorption axis 10a of the polarizer 10 form an angle θ of 45 ± 20° or 135 ± 20°. When the angle θ is out of this range, it is not easy to obtain a function of converting the linearly polarized light into a circularly polarized light, and as a result, the brightness at the time of seeing the screen through the polarized sunglasses tends to decrease. The ideal angle θ is 45 ± 10 ° or 135 ± 10 °, more preferably 45 ± 5 ° or 135 ± 5 °.

The optical film 20 may further contain a film of a light transmissive (preferably optically transparent) thermoplastic resin. Examples of the thermoplastic resin include a polyolefin resin such as a linear polyolefin resin (such as a polypropylene resin) or a cyclic polyolefin resin (a norbornene resin); for example, cellulose triacetate Cellulose ester of acid ester and cellulose diacetate A cellulose resin such as a resin; a polyester resin; a polycarbonate resin; a (meth)acrylic resin; a polystyrene resin; or a mixture or a copolymer thereof.

In addition to a homopolymer of a chain olefin such as a polyethylene resin or a polypropylene resin, a copolymer of two or more kinds of chain olefins may be mentioned as the chain polyolefin resin.

The cyclic polyolefin resin is a general term for a resin obtained by polymerizing a cyclic olefin as a polymerization unit. Specific examples of the cyclic polyolefin-based resin include a ring-opened (co)polymer of a cyclic olefin, an addition polymer of a cyclic olefin, and a copolymer of a cyclic olefin and a chain olefin such as ethylene or propylene ( Representative examples are random copolymers, and graft polymers which have been modified with unsaturated carboxylic acids or derivatives thereof, and such hydrides and the like. Among them, a norbornene-based resin using a norbornene-based monomer, such as a norbornene or a polycyclic norbornene-based monomer, which is a cyclic olefin, is preferably used.

The cellulose ester resin is an ester of cellulose and a fatty acid. Specific examples of the cellulose ester-based resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Further, it is also possible to use such a copolymer or a part of a hydroxyl group which is modified by another substituent. Among these, cellulose triacetate (triacetyl cellulose: TAC) is particularly preferred.

The polyester resin is an ester bond and is a resin other than the cellulose ester resin, and is generally composed of a polyvalent carboxylic acid or a polycondensate of the derivative and the polyol. As the polycarboxylic acid or a derivative thereof, a divalent dicarboxylic acid or a derivative thereof can be used, and for example, p-benzoic acid can be cited. Formic acid, isophthalic acid, dimethyl terephthalate, dimethyl naphthalate or the like. As the polyol, a divalent diol can be used, and examples thereof include ethylene glycol, propylene glycol, butanediol, neopentyl glycol, and cyclohexane dimethanol.

Specific examples of the polyester resin include: polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, dibutyl naphthalate, polytrimethylene terephthalate Methyl ester, polytrimethylene naphthalate, dimethyl dimethyl terephthalate, cyclohexane dimethyl phthalate.

The polycarbonate resin is a polymer in which a monomer unit having a carboxylate group is bonded. The polycarbonate resin may also be a resin called modified polycarbonate such as a polymer backbone, or a copolymerized polycarbonate or the like.

The (meth)acrylic resin is a resin in which a compound having a (meth)acryl fluorenyl group is used as a main structural monomer. Specific examples of the (meth)acrylic resin include, for example, poly(meth)acrylate such as polymethyl methacrylate; methyl methacrylate-(meth)acrylic acid copolymer; methyl methacrylate -(meth)acrylate copolymer; methyl methacrylate-acrylate-(meth)acrylic acid copolymer; methyl (meth)acrylate-styrene copolymer (MS resin, etc.); methyl methacrylate A copolymer with a compound having an alicyclic hydrocarbon group (for example, a methyl methacrylate-cyclohexyl methacrylate copolymer, a methyl methacrylate-norbornyl (meth)acrylate copolymer, etc.). It is desirable to use a polymer having a poly(methyl) acrylate poly(methyl) acrylate C _1-6 alkyl ester as a main component, and more desirably, methyl methacrylate is used. The main component (50 to 100% by weight, desirably 70 to 100% by weight) of a methyl methacrylate-based resin.

The optical film 20 can be produced by stretching a film containing the thermoplastic resin or by applying a phase difference exhibiting substance such as a liquid crystal material which exhibits a phase difference to a film containing the thermoplastic resin. Examples of the elongation handler include uniaxial stretching or biaxial stretching. The direction of the extension may be, for example, a mechanical flow direction (MD) of the unstretched film, a direction perpendicular thereto (TD), a direction oblique to the mechanical flow direction (MD), and the like. The biaxial extension may be a biaxial extension that extends simultaneously while extending in two extension directions, or a sequential biaxial extension that extends in other directions after extending in a specified direction. The stretching treatment, for example, using two or more pairs of nip rolls having a large peripheral speed on the outlet side, or extending in the long direction (mechanical flow direction: MD), supporting the both ends of the unstretched film with a chuck, The mechanical flow direction is expanded in the vertical direction (TD). At this time, the phase difference value can be controlled within the range of the above formulas (1) to (2) by adjusting the thickness of the film or adjusting the stretching ratio. Further, the wavelength dispersion value can be controlled within the range of the above formulas (3) to (4) by adding a wavelength dispersion adjusting agent to the resin.

The thickness d of the optical film 20 is not particularly limited as long as it satisfies the above formulae (1) to (4), but is preferably 90 μm or less, and more preferably 60 μm or less from the viewpoint of reduction in thickness of the optical layered body. Further, from the viewpoint of the rationality of the optical film 20, it is preferably 5 μm or more, and more preferably 10 μm or more.

The optical film 20 may contain one type or two or more types such as a slip agent, a plasticizer, a dispersant, a heat stabilizer, and an ultraviolet absorber. Infrared absorber, antistatic agent, antioxidant additive.

Further, in order to impart desired optical characteristics or other characteristics, a coating layer (surface treatment layer) may be provided on the outer surface of the optical film 20. Specific examples of the coating layer include a hard coat layer, an antiglare layer, an antireflection layer, an antistatic layer, and an antifouling layer. The method of forming the coating layer is not particularly limited, and a conventional method can be used.

[d] thermoplastic resin film

The first thermoplastic resin film 40 (see FIG. 3) which can be laminated on the surface opposite to the optical film 20 in the polarizing plate 10, or the second thermoplastic layer between the polarizer 10 and the optical film 20 can be used. A specific example of the thermoplastic resin constituting the film of the resin film 60 (see Fig. 4) can be the same as the above-described examples relating to the optical film 20. In the case where both the first thermoplastic resin film 40 and the second thermoplastic resin film 60 are present, both of them may be composed of the same thermoplastic resin, or may be composed of different kinds of thermoplastic resins.

The first thermoplastic resin film 40 and the second thermoplastic resin film 60 may be a protective film that functions only as a protective polarizer 10, but in particular, the first thermoplastic resin film 40 disposed on the image display element side of the polarizer 10 may be used. It is a protective film which simultaneously has an optical function as a retardation film. For example, the retardation layer can be formed by stretching a film containing the thermoplastic resin or by applying a phase difference material such as a liquid crystal material which exhibits a phase difference on a film containing the thermoplastic resin, thereby imparting an arbitrary retardation value. The phase difference film.

The first thermoplastic resin film 40 and the second thermoplastic tree The thickness of the thickness of the optical film 60 is preferably 90 μm or less, more preferably 60 μm or less, from the viewpoint of thinning of the optical layered body, and is preferably 5 μm or more from the viewpoint of handleability, and more preferably It is 10 μm or more.

[e]Adhesive layer and adhesive layer

The first adhesive layer as the first adhesive layer or the adhesive layer 25 (see FIGS. 1 to 4) can be used, and the second surface on the surface opposite to the optical film 20 in the polarizing film 10 can be laminated. The adhesive layer 30 (see FIG. 2) and the third adhesive layer 50 (see FIG. 3) and the fourth adhesive layer which are laminated on the surface of the first thermoplastic resin film 40 opposite to the polarizer 10 (see FIG. 3) The adhesive for the adhesive layer of the fourth adhesive layer (see FIG. 3) of the adhesive layer 45 may be, for example, a (meth)acrylic adhesive, an amine ester adhesive, or an anthrone adhesive. Polyester adhesive, polyamine adhesive, polyether adhesive, fluorine adhesive, rubber adhesive, etc., but from transparency, adhesion, reliability, rework From the viewpoint of the use, a (meth)acrylic adhesive is preferably used. In the case where the optical laminate is a plurality of adhesive layers, the adhesive compositions constituting the adhesive layers may have the same composition or may have mutually different compositions.

The (meth)acrylic adhesive is usually a (meth)acrylic resin as a base polymer, and an adhesive such as a crosslinking agent of an isocyanate compound, an epoxy compound or an aziridine compound is added thereto. Made up of components. The adhesive composition may also contain fine particles as an adhesive layer which exhibits light scattering. The thickness of the adhesive layer is usually from 1 to 40 μm, preferably from 3 to 25 μm.

The adhesive layer may be provided, for example, by using an adhesive in the form of an organic solvent solution, on the surface of the adhesive layer, by coating or drying, or in a plastic film which has been subjected to release treatment ( The formed sheet-like adhesive is formed on the surface of the adhesive layer by a transfer method.

As an adhesive layer (see FIGS. 1 to 4) for forming the first adhesive layer or the adhesive layer 25, an adhesive layer of the fourth adhesive layer or the adhesive layer 45 (see FIG. 3), For the adhesive of the subsequent agent layer 65 (refer to Fig. 4), for example, a water-based adhesive or an active energy ray-curable adhesive can be used. Examples of the water-based adhesive include an adhesive made of a polyvinyl alcohol-based resin aqueous solution, and an aqueous two-component amine ester-based latex adhesive. In particular, in the case of a cellulose ester-based resin film which is subjected to surface treatment (hydrophilization treatment) such as saponification treatment, it is preferred to use a water-based adhesive made of a polyvinyl alcohol-based resin aqueous solution.

As a polyvinyl alcohol-based resin, in addition to a polyvinyl alcohol homopolymer obtained by saponifying a polyvinyl acetate homopolymer of vinyl acetate, it is also possible to use an ethyl acetate together with it. A polyvinyl alcohol-based copolymer obtained by saponification of a copolymer of another monomer to be polymerized, or a modified polyvinyl alcohol-based polymer obtained by partially modifying such a hydroxyl group. The aqueous binder may contain an additive such as a polyvalent aldehyde, a water-soluble epoxy compound, a melamine-based compound, a zirconium compound, or a zinc compound.

The water-based adhesive is applied to the bonding surface of at least one of the two bonded films, and the films are bonded together via the adhesive layer, and it is preferably pressurized by using a bonding roll or the like. Make it dense to implement fit. The coating method of the aqueous adhesive (the active energy ray-curable adhesive to be described later is also the same) is not particularly limited, and a casting method, a Meyer bar coating method, a gravure coating method, and a missing angle coating method can be used. Conventional methods such as a knife coating method, a die coating method, a dip coating method, and a spray method.

In the case of using a water-based adhesive, it is preferred to dry the film in order to remove water contained in the aqueous adhesive after the above-described bonding. Drying can be carried out, for example, by introducing a film into a drying oven. The drying temperature (temperature of the drying oven) is desirably 30 to 90 °C. When the temperature is less than 30 ° C, the adhesion is likely to be insufficient. When the drying temperature exceeds 90 ° C, the polarizing performance via the thermal polarizer 10 may be deteriorated.

After the drying step, a curing step of about 12 to 600 hours may be provided at room temperature or a temperature slightly higher than this, for example, at a temperature of about 20 to 45 ° C. The curing temperature is generally set lower than the drying temperature.

The active energy ray-curable adhesive is an adhesive which is cured by irradiation with an active energy ray such as ultraviolet rays, visible rays, electron rays, or X-rays. In this case, the adhesive layer is a cured layer of an active energy ray-curable adhesive. The active active energy ray-curable adhesive is a photocurable adhesive, and more preferably an ultraviolet curable adhesive.

Examples of the photocurable adhesive include those containing a polymerizable compound and a photopolymerization initiator, those containing a photoreactive resin, and those containing an adhesive resin and a photoreactive crosslinking agent. The polymerizable compound may, for example, be a photocurable epoxy-based monomer, a photocurable acrylic monomer, or a photocurable amine ester-based monomer. Or an oligomer derived from a photopolymerizable monomer. As a photopolymerization initiator, those which contain an active species such as a neutral radical, an anion radical, or a cationic radical generate light by ultraviolet light irradiation. As the photocurable adhesive containing a polymerizable compound and a photopolymerization initiator, those containing a photocurable epoxy monomer and a photocationic polymerization initiator can be preferably used.

In the case of using an active energy ray-curable adhesive, after performing the above-described bonding, a drying step is performed as needed (in the case where the active energy ray-curable adhesive is a solvent, etc.), and secondly, by irradiating active energy such as ultraviolet rays The hardening step is performed by curing the active energy ray-curable adhesive. Although the active energy ray for irradiation is not particularly limited, it is preferably an ultraviolet ray having a light-emitting distribution at a wavelength of 400 nm or less. Specifically, as a light source, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, and a chemical are used. Lights, black lights, microwaves, mercury lamps, metal halide lamps, etc. are preferred.

When the film is bonded, at least one of the film bonding surfaces may be subjected to surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame treatment, saponification treatment, etc. in order to improve adhesion. The treatment) is preferably performed by plasma treatment, corona treatment or saponification treatment. For example, when the film to be bonded is formed of a cyclic polyolefin resin, it may be subjected to plasma treatment or corona treatment. Further, in the case of a cellulose ester-based resin, a saponification treatment can be performed. As the saponification treatment, a method of immersing in an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide can be mentioned.

<Portrait display device>

In the image display device according to the present invention, the optical layered body of the present invention is disposed on the side of the image display element, and the polarizer of the optical layered body is disposed on the image display element side. The image display element may be a non-self-luminous type element such as a liquid crystal cell, or may be a self-luminous type element such as an organic EL display element. The liquid crystal element is a liquid crystal layer sandwiched between two transparent substrates, and is displayed by an applied voltage to control the alignment state of the liquid crystal layer. A well-known person can be used in the field of liquid crystal display. The organic EL display element is one in which an illuminant containing an organic luminescent material is sandwiched by a pair of electrodes, and it is naturally possible to employ a person well-known in the art.

An example of a liquid crystal display device using the liquid crystal element 70 in the image display element is shown in Fig. 7. In this example, the optical layered body 2 shown in FIG. 2 is suitably used. However, the image display apparatus is only required to include the optical layered body according to the present invention. The optical layering system as shown in Fig. 7 can be attached to the image display element by using an adhesive layer or the like. In the liquid crystal display device, the polarizing plate 80 is disposed on the backlight plate 90 side of the liquid crystal element 70. However, the polarizing plate 80 may be bonded to the image display element by using the adhesive layer 85 or the like. As the polarizing plate 80 and the backlight 90 on the backlight side, a conventionally known component can be used.

In the optical layering system of the image display device according to the present invention, the optical film 20 is disposed on the image display element such that the optical film 20 is disposed closer to the side than the polarizer 10 (so that the polarizer 10 is on the image display element side). . The image display device including the optical laminate of the present invention is seen through various directions (azimuth and polar angle) through polarized sunglasses. The brightness at the time of the screen is good, and the change in color tone is also small, and the visibility is excellent.

[Examples]

Hereinafter, the present invention will be more specifically described by showing examples and comparative examples, but the present invention is not limited to these examples.

<Example 1>

(1) Production of polarizer

A polyvinyl alcohol film having a thickness of 75 μm (average degree of polymerization of about 2400, a degree of saponification of 99.9 mol% or more) was uniaxially stretched by about 5 times by dry stretching, and further kept at a state of tension at 60 ° C. After immersing in pure water for 1 minute, it was immersed in an aqueous solution of iodine/potassium iodide/water at a weight ratio of 0.05/5/100 at 28 ° C for 60 seconds. Thereafter, it was immersed in an aqueous solution of 72 ° C in a weight ratio of potassium iodide/boric acid/water of 8.5/8.5/100 for 300 seconds. After continuously washing with pure water at 26 ° C for 20 seconds, it was dried at 65 ° C to obtain a polarizer having a thickness of 28 μm in which iodine was adsorbed in a polyvinyl alcohol film.

(2) Production of polarizing plate

3 parts by weight of carboxy-modified polyvinyl alcohol [trade name "KL-318" obtained from Kuraray Co., Ltd., Japan] was dissolved in 100 parts by weight of water, and 1.5 parts by weight of water-soluble epoxy resin was added to the aqueous solution. A polyamine-based epoxy-based additive [Sumirez resin 650 (30)" obtained from the company of Takaoka Chemical Industry Co., Ltd., and an aqueous solution having a solid concentration of 30% by weight] was prepared to prepare a water-based adhesive. This adhesive was applied to one surface of the polarizer obtained in the above (1), and a triacetyl cellulose (TAC) film having a thickness of 40 μm was attached to the coated surface [Konica Minolta Optical Co., Ltd. After the protective film of "KC4UY", the adhesive layer was dried to obtain a polarizing plate having a layer structure of a TAC film/adhesive layer/polarizer.

(3) Production of optical laminates

On the TAC film surface of the polarizing plate obtained in the above (2), the optical film A was bonded to the surface of the TAC film having a thickness of 25 μm (trade name "#7" manufactured by Lintec Co., Ltd.). A polycarbonate film manufactured by the company, "Purex® RM", having a thickness of 53 μm, was obtained to obtain an optical laminate. The formation angle θ of the slow axis of the optical film A and the absorption axis of the polarizer is set to 45°.

<Examples 2 to 3, Comparative Examples 1 to 6>

In the first embodiment, an optical laminate was produced in the same manner except that the optical film described below was used instead of the optical film A.

Example 2: Optical film B [TAC film, thickness 43 μm]

Example 3: Optical film C [Polymer film manufactured by Teijin Chemical Co., Ltd., trade name "Purex® WR", thickness 53 μm]

Comparative Example 1: Optical film D [a film made of a cyclic polyolefin made by Zeon, Japan, trade name "ZEONOR® film ZF35-film #140", thickness 28 μm]

Comparative Example 2: Optical film E [a film of a cyclic polyolefin film manufactured by Zeon Co., Ltd., trade name "ZEONOR® film ZF35-film #110", thickness 28 μm]

Comparative Example 3: Optical film F [film made of a cyclic polyolefin, thickness 20 μm]

Comparative Example 4: Optical film G [a film made of a cyclic polyolefin made by Zeon, Japan, trade name "ZEONOR® film ZD12", thickness 33 μm]

Comparative Example 5: Optical film H [polycarbonate film manufactured by Kaneka Co., Ltd., trade name "RB-film #130", thickness 25 μm]

Comparative Example 6: Optical film I [polyester film manufactured by Toray Industries, trade name "Lumirror 4 ZY004", thickness 5 μm].

(Measurement of phase difference characteristics and wavelength dispersion characteristics of optical films)

In an environment of a temperature of 23 ° C and a relative humidity of 55%, an automatic birefringence meter (KOBRA-WPR) manufactured by Oji Scientific Instruments Co., Ltd. was used, and the optical films A to I used in the examples and the comparative examples were measured for R _e ( 590), R _th (590), R _e (450), R _e (550), R _e (630), calculate R _th (590) / R _e (590), R _e (450) / R _e (550), R _e (630)/R _e (550). The results are shown in Table 1.

(evaluation of hue change)

Referring to Figs. 8(a) and 8(b), which schematically show the color tone change measurement system, first, the polarizing plate surface of the optical layered body made of the polarizing plate and the optical film and the glass plate are sandwiched by a sheet having a thickness of 25 μm. The adhesive [product name "#7" manufactured by Lintec Co., Ltd.] was attached to each other to obtain a sample for evaluation. Next, the evaluation sample was attached to a viewing angle characteristic measurement and evaluation device [trade name "EZ Contrast" manufactured by ELDIM Co., Ltd.]. At this time, the sample for evaluation is arranged in the order of a light source (cold cathode line), a glass plate, a polarizing plate, an optical film, and a light receiving unit (camera). Further, between the optical film of the optical laminate and the light receiving portion, a polarizing plate which is assumed to be polarized sunglasses is used to absorb the absorption axis of the polarizing plate which is assumed to be an optical laminate and the polarizing plate which is assumed to be polarized sunglasses. The shaft is formed in such a manner as a crossed prism. In any of the examples and comparative examples, false The polarizing plate produced in Example 1 was used as the polarizing plate of the polarized sunglasses (the same as the polarizing plate included in the optical laminate).

The azimuth angles 0, 45, 90, 135, 180, 225, 270 in the polar angles 0, 10, 20, 30, 40, 50, 60, 70, 80° are measured by the above-described viewing angle characteristic measurement evaluation device. The chromaticity of 315 ° (9 × 8 = 72 points) was used to obtain the (x, y) value of the CIE-XYZ color system. Then, the difference Δy between the maximum value and the minimum value of the maximum value Δx,y of the 72 points is obtained, and the total value Δx+Δy is evaluated based on the following evaluation criteria. The change in color tone when viewing the picture from various directions (azimuth and polar angle) through polarized sunglasses. The results are shown in Table 1. Further, the xy chromaticity diagrams obtained in the respective examples and comparative examples are shown in the figures 9 to 17.

A: Δx + Δy is less than 0.065

B: Δx + Δy is 0.065 or more and less than 0.100

C: Δx + Δy is 0.100 or more.

Claims (9)

An optical layered body comprising a polarizer and an optical film laminated on one side of the polarizer, wherein the optical film is formed by converting linearly polarized light into rounded polarized light, and satisfies the following formula: (1) 100 nm≦R _e (590)≦180 nm, (2)0.5<R _th (590)/R _e (590)≦0.8, (3)0.85≦R _e (450)/R _e (550)<1.00, and 4) 1.00 < R _e (630) / R _e (550) ≦ 1.1 [wherein, R _e (590), R _e (450), R _e (550), R _e (630), respectively, at the measurement wavelength In-plane retardation values of 590 nm, 450 nm, 550 nm, and 630 nm, and R _th (590) is a thickness direction phase difference value at a measurement wavelength of 590 nm. The optical layered body according to claim 1, wherein an angle formed by the slow axis of the optical film and the absorption axis of the polarizer is 45 ± 20° or 135 ± 20°. The optical layered product according to claim 1 or 2, wherein the optical film contains a cyclic polyolefin resin, a polycarbonate resin, a cellulose resin, a polyester resin or (meth) Acrylic resin. The optical layered product according to claim 1 or 2, wherein the optical film is laminated on the polarizer via a first adhesive layer or an adhesive layer. For example, if the optical laminate described in claim 1 or 2 is applied, The step includes a second adhesive layer laminated on a surface of the polarizer opposite to the optical film. The optical layered product according to claim 1 or 2, further comprising a thermoplastic resin film laminated on a surface of the polarizer opposite to the optical film. The optical laminate according to claim 6, wherein the thermoplastic resin film is a retardation film. The optical laminate according to claim 6, further comprising a third adhesive layer laminated on a surface of the thermoplastic resin film opposite to the polarizer. An image display device comprising an image display device, and the optical laminate according to any one of claims 1 to 8, wherein the optical layering system is such that the polarizer is on the side of the image display element And configuration.