JP2013101409A - Laminate film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate film that can improve display uniformity of a liquid crystal display device, and to provide a laminate film excellent in adhesiveness to a liquid crystal cell as well as excellent in light release property.SOLUTION: The laminate film includes at least a polarizing plate, a retardation film and a first pressure-sensitive adhesive layer, in this order. The polarizing plate comprises a polarizer, a first protective layer disposed on a side of the polarizer where the retardation film is present, and a second protective layer disposed on the other side of the polarizer opposite to the side where the retardation film is present. The retardation film is a stretched film containing a norbornene resin. The first pressure-sensitive adhesive layer comprises an adhesive obtained by crosslinking a composition prepared by compounding a (meth)acrylate (co)polymer and a crosslinking agent essentially comprising a peroxide such as diallylperoxides.

Description

  The present invention relates to a laminated film having a polarizing plate, a retardation film, and an adhesive layer.

  Liquid crystal display devices are attracting attention for their features such as thinness, light weight, and low power consumption. Mobile devices such as mobile phones and watches; OA devices such as personal computer monitors and laptop computers; and home appliances such as video cameras and liquid crystal televisions. Widely popular. Conventionally, a laminated film in which a polarizing plate and a retardation film are laminated is used for a liquid crystal display device. For example, a laminated film in which a polarizing plate and a retardation film having a refractive index ellipsoid having a relationship of nx> nz> ny are laminated on one side of an in-plane switching (IPS) liquid crystal cell, A method for improving the contrast ratio in the direction is disclosed (see Patent Document 1). However, in a liquid crystal display device obtained using a conventional laminated film, for example, when a screen displaying a black image is viewed from an oblique direction, the color changes greatly depending on the viewing direction (the color shift amount is also large). ) When the backlight is turned on for a certain period of time, there is a problem that optical unevenness occurs on the screen.

Usually, a laminated film is stuck to a liquid crystal cell through an adhesive layer. However, with conventional laminated films, it is difficult to peel the laminated film from the liquid crystal cell, or after peeling the laminated film, the members (retardation film or adhesive layer) constituting the laminated film are the surface of the liquid crystal cell. There was a problem that it remained on the surface. Generally, a liquid crystal display device is inspected before shipping. At this time, when the laminated film itself has a defect or foreign matter is mixed between the laminated film and the liquid crystal cell, the laminated film is peeled off in order to reuse the liquid crystal cell (also referred to as rework). ). Ideally, the laminated film should adhere to the liquid crystal cell so that it does not peel off or generate bubbles even in high temperature and high humidity environments. It must be easy to peel off from the liquid crystal cell so that the gap does not change or break. In the prior art, it has been difficult to achieve such conflicting properties. For this reason, the laminated | multilayer film with which this subject was solved was desired.

JP-A-11-305217

The present invention has been made to solve such problems, and an object thereof is to provide a laminated film capable of improving the display uniformity of a liquid crystal display device. Furthermore, it is providing the laminated film which is excellent in adhesiveness with a liquid crystal cell, and excellent in light peelability.

As a result of intensive studies to solve the above problems, the present inventors have found that the above object can be achieved by the laminated film shown below, and have completed the present invention.

The laminated film of the present invention comprises at least a polarizing plate, a retardation film, and a first pressure-sensitive adhesive layer in this order,
The polarizing plate includes a polarizer, a first protective layer disposed on a side including the retardation film of the polarizer, and a second disposed on a side opposite to the side including the retardation film of the polarizer. Including a protective layer,
The retardation film is a stretched film containing a norbornene resin,
This 1st adhesive layer contains the adhesive which can be obtained by bridge | crosslinking the composition which mix | blended at least the (meth) acrylate type | system | group (co) polymer and the crosslinking agent which has a peroxide as a main component.

In a preferred embodiment, the first protective layer and / or the second protective layer is a polymer film containing a cellulose resin.

In a preferred embodiment, the first protective layer is substantially optically isotropic.

In a preferred embodiment, the refractive index ellipsoid of the first protective layer has a relationship of nx≈ny ≧ nz:
Where nx, ny and nz are the refractive index in the slow axis direction, the refractive index in the fast axis direction, and the refractive index in the thickness direction, respectively.

In a preferred embodiment, the refractive index ellipsoid of the retardation film has a relationship of nx>nz> ny:
Where nx, ny and nz are the refractive index in the slow axis direction, the refractive index in the fast axis direction, and the refractive index in the thickness direction, respectively.

In a preferred embodiment, Re [590] of the retardation film is 80 nm to 350 nm:
However, Re [590] is an in-plane retardation value measured with light having a wavelength of 590 nm at 23 ° C.

In a preferred embodiment, the retardation film has an Nz coefficient of 0.1 to 0.7:
However, the Nz coefficient is a value calculated from the formula: Rth [590] / Re [590], and Re [590] and Rth [590] are surfaces measured with light having a wavelength of 590 nm at 23 ° C., respectively. It is the phase difference value in the inside and the phase difference value in the thickness direction.

In a preferred embodiment, the absolute value of the photoelastic coefficient measured with light having a wavelength of 590 nm at 23 ° C. of the retardation film is 1 × 10 ⁻¹² to 10 × 10 ⁻¹² .

In a preferred embodiment, the adhesive strength for a glass plate at 23 ° C. of the first pressure-sensitive adhesive layer (F _1A) is located at 2N / 25mm~10N / 25mm:
However, the above adhesive strength is the adhesion when a 25 mm wide laminated film is pressed once on a glass plate with a 2 kg roller, cured at 23 ° C. for 1 hour, and then peeled off at 90 mm direction at 300 mm / min. It is strength.

In a preferred embodiment, the anchoring force (F _1B ) of the first pressure-sensitive adhesive layer on the retardation film at 23 ° C. is 10 N / 25 mm to 40 N / 25 mm:
However, the throwing force is such that a laminate of a 25 mm wide adhesive layer and a retardation film is pressed once on a treated surface of a polyethylene terephthalate film vapor-deposited with indium tin oxide with a 2 kg roller at 23 ° C. It is the adhesive strength when the polyethylene terephthalate film is peeled off at 300 mm / min in the 180 ° direction together with the pressure-sensitive adhesive layer after culturing for 1 hour.

In a preferred embodiment, the throwing force (F _1B ) of the first pressure-sensitive adhesive layer on the retardation film at 23 ° C., and the adhesion force (F _1A ) of the first pressure-sensitive adhesive layer to the glass plate at 23 ° C. Difference (F _1B −F _1A ) is 5 N / 25 mm or more:
However, the throwing force is such that a laminate of a 25 mm wide adhesive layer and a retardation film is pressed once on a treated surface of a polyethylene terephthalate film vapor-deposited with indium tin oxide with a 2 kg roller at 23 ° C. It is the adhesive strength when the polyethylene terephthalate film is peeled off at 300 mm / min in the direction of 180 degrees together with the pressure-sensitive adhesive layer after cultivating for 1 hour. The above adhesive strength is obtained by laminating a 25 mm wide laminated film on a glass plate with a 2 kg roller. This is the adhesive strength when the laminated film is peeled off at 300 mm / min in the 90-degree direction after reciprocating pressure bonding and curing at 23 ° C. for 1 hour.

In a preferred embodiment, the (meth) acrylate (co) polymer is a (meth) acrylate monomer having a linear or branched alkyl group having 1 to 8 carbon atoms, and at least one hydrogen atom is substituted with a hydroxyl group. And a copolymer with a (meth) acrylate monomer having a straight-chain or branched alkyl group having 1 to 8 carbon atoms.

In preferable embodiment, the compounding quantity (weight ratio) of the crosslinking agent which has the said peroxide as a main component is 0.01-1.0 with respect to the said (meth) acrylate type | system | group (co) polymer 100. FIG.

In a preferred embodiment, the first pressure-sensitive adhesive layer comprises a (meth) acrylate-based (co) polymer, a peroxide-based crosslinking agent, an isocyanate group-containing compound, a silane coupling agent, A pressure-sensitive adhesive that can be obtained by crosslinking a composition containing at least
The compounding amount (weight ratio) of the compound having an isocyanate group is 0.005 to 1.0 with respect to the (meth) acrylate-based (co) polymer 100,
The blending amount (weight ratio) of the silane coupling agent is 0.001 to 2.0 with respect to the (meth) acrylate (co) polymer 100.

In preferable embodiment, the glass transition temperature (Tg) of the said adhesive is -70 degreeC--10 degreeC.

In preferable embodiment, the moisture content of the said adhesive is 1.0% or less.

In a preferred embodiment, a second pressure-sensitive adhesive layer is further provided between the polarizing plate and the retardation film,
The second pressure-sensitive adhesive layer is obtained by crosslinking a composition containing at least a (meth) acrylate-based (co) polymer, a crosslinking agent mainly composed of a compound having an isocyanate group, and a silane coupling agent. A pressure sensitive adhesive.

According to another aspect of the present invention, a liquid crystal panel is provided. The liquid crystal panel includes at least the laminated film and a liquid crystal cell.

According to another aspect of the present invention, a liquid crystal display device is provided. The liquid crystal display device includes the liquid crystal panel.

By using a stretched film containing a norbornene-based resin as the retardation film in the laminated film of the present invention, it is possible to obtain a liquid crystal display device that is less likely to cause optical unevenness due to strain and has excellent display uniformity. When the refractive index ellipsoid of the retardation film has a relationship of nx> nz> ny, the liquid crystal display in which the light leakage in the oblique direction and the color shift in the oblique direction are much smaller than those of the conventional liquid crystal display device. A device can be obtained. Furthermore, the laminated film of the present invention can be firmly adhered to the retardation film by using an adhesive that can be obtained by crosslinking a specific composition as the adhesive layer. In addition, a practically sufficient adhesive force and bonding time can be obtained with respect to the substrate (glass plate) of the liquid crystal cell without causing peeling or bubbles even in a high temperature and high humidity environment. On the other hand, when the laminated film of the present invention is peeled off from the liquid crystal cell and reused, the pressure-sensitive adhesive layer or retardation film does not remain on the surface of the liquid crystal cell and can be peeled off with a light force. it can. Therefore, the cell gap of the liquid crystal cell does not change or the substrate is not damaged, and the productivity of the liquid crystal display device can be greatly improved.

It is a schematic sectional drawing of the laminated | multilayer film by preferable embodiment of this invention. It is a schematic diagram which shows the concept of the typical manufacturing process of the polarizer used for this invention. It is a schematic diagram which shows the concept of the typical manufacturing process of the phase difference film used for this invention. It is a schematic diagram which shows the concept of the typical manufacturing process of the 1st adhesive layer used for this invention. It is a schematic sectional drawing of the laminated | multilayer film by one Embodiment of this invention. It is a schematic sectional drawing of the liquid crystal panel by preferable embodiment 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. It is a graph which shows the relationship between the in-plane retardation value Re ([590]) of the retardation film obtained in Reference Examples 1-12, and a Nz coefficient. It is a graph which shows the relationship between the in-plane retardation value Re ([590]) of the retardation film obtained in Reference Examples 1-12, and the thickness direction retardation value (Rth [590]). It is a graph which shows the Y value of the polar angle 60 degrees of the liquid crystal display device of Example 3 and the comparative example 3, and azimuth | direction angles 0 degree-360 degrees. It is a graph which shows ⁽ DELTA) a ^* b ^* value of the polar angle of the liquid crystal display device of Example 3 and the comparative example 3 of 60 degrees, and an azimuth angle of 0 degrees-360 degrees. It is a photograph of the surface of a glass plate after peeling the laminated | multilayer film of Example 4. FIG. It is a photograph of the surface of a glass plate after peeling the laminated | multilayer film of the comparative example 4.

A. 1 is a schematic cross-sectional view of a laminated film according to a preferred embodiment of the present invention. It should be noted that, for the sake of easy understanding, the ratio of the length, width, and thickness of each component in FIG. 1 is described differently from the actual one. The laminated film 10 includes a polarizing plate 20, a retardation film 30, and a first pressure-sensitive adhesive layer 41 in at least this order. The polarizing plate 20 is disposed on the opposite side of the polarizer 21, the first protective layer 22 disposed on the side of the polarizer 21 including the retardation film 30, and the side of the polarizer 21 including the retardation film 30. Second protective layer 23. The retardation film 30 is a stretched film containing a norbornene resin. The 1st adhesive layer 41 contains the adhesive which can be obtained by bridge | crosslinking the composition which mix | blended at least the (meth) acrylate type | system | group (co) polymer and the crosslinking agent which has a peroxide as a main component. When such a laminated film is used in a liquid crystal display device, optical unevenness is hardly caused by strain, and excellent display uniformity can be obtained. In addition, even in a high temperature and high humidity environment, a practically sufficient adhesive force and bonding time can be obtained without causing peeling or bubbles. On the other hand, when it peels from a liquid crystal cell, it has the characteristics that it is excellent in light peelability (it is also called rework property).

In the present invention, between the retardation film 30 and the first protective layer 22, between the first protective layer 22 and the polarizer 21, and between the polarizer 21 and the second protective layer 23, An optional adhesive layer (not shown) can be placed. In this specification, the “adhesive layer” refers to a layer that joins surfaces of adjacent optical members and integrates them with practically sufficient adhesive force and adhesion time. Specific examples of the adhesive layer include an adhesive layer, a pressure-sensitive adhesive layer, and an anchor coat layer. The adhesive layer may have a multilayer structure in which an anchor coat layer is formed on the surface of an adherend, and an adhesive layer or a pressure-sensitive adhesive layer is formed thereon, or may not be recognized visually. A thin layer (also referred to as a hairline) may be used.

Practically, a release liner (not shown) may be disposed on the side of the first pressure-sensitive adhesive layer 41 opposite to the side provided with the retardation film 30. A surface protective film (not shown) may be disposed on the side of the second protective layer 23 opposite to the side provided with the polarizer 21. The release liner and the surface protective film are used for preventing the laminated film from becoming dirty or damaged during the production process or transportation. Therefore, the release liner and the surface protective film are usually peeled before the laminated film is put into practical use.

The thickness of the laminated film is preferably 100 μm to 600 μm, more preferably 200 μm to 400 μm. By setting the thickness of the laminated film in the above range, a film having excellent mechanical strength can be obtained.

In addition, the laminated | multilayer film of this invention are not limited to said embodiment. For example, other constituent members may be disposed between the constituent members illustrated in FIG. Hereinafter, each member and each layer constituting the laminated film of the present invention will be described in detail.

B. Referring to FIG. 1, a polarizing plate 20 used in the present invention includes a polarizer 21, a first protective layer 22 disposed on the side of the polarizer 21 that includes the retardation film 30, and a polarizer 21. A second protective layer 23 disposed on the side opposite to the side including the retardation film 30 is included. The first protective layer 22 and the second protective layer 23 of the polarizing plate 20 may be the same or different from each other.

Preferably, the polarizing plate 20 is provided with an adhesive layer (not shown) between the polarizer 21 and the first protective layer 22 and between the polarizer 21 and the second protective layer 23, respectively. Each protective layer and polarizer are attached. Thus, a polarizing plate excellent in mechanical strength can be obtained by sandwiching a polarizer with a protective layer. Furthermore, it is possible to prevent the polarizer from expanding or contracting even under a high temperature and high humidity environment, and as a result, a polarizing plate having excellent optical characteristics can be obtained.

The thickness of the polarizing plate is preferably 45 μm to 250 μm, and more preferably 70 μm to 220 μm. By setting the thickness of the polarizing plate in the above range, a material having excellent mechanical strength can be obtained.

The transmittance at a wavelength of 550 nm (also referred to as single transmittance) measured at 23 ° C. of the polarizing plate is preferably 40% or more, and more preferably 42% or more. Note that the theoretical upper limit of the single transmittance is 50%, and the realizable upper limit is 46%.

The polarization degree of the polarizing plate is preferably 99.8% or more, and more preferably 99.9 or more. The theoretical upper limit of the degree of polarization is 100%. By setting the single transmittance and the degree of polarization within the above ranges, a liquid crystal display device with small light leakage in the front direction (as a result, high contrast) can be obtained.

The hue of the polarizing plate according to National Bureau of Standards (NBS); the a value (single a value) is preferably −2.0 or more, more preferably −1.8 or more. Note that the ideal value of the a value is zero. The hue of the polarizing plate according to National Bureau of Standards (NBS); b value (single b value) is preferably 4.2 or less, and more preferably 4.0 or less. Note that the ideal value of the b value is zero. By setting the a value and b value of the polarizing plate to values close to 0, a liquid crystal display device with vivid colors of the display image can be obtained.

The single transmittance, polarization degree, and hue can be measured using a spectrophotometer [Murakami Color Research Laboratory, product name “DOT-3”]. As a specific method for measuring the degree of polarization, the parallel transmittance (H ₀ ) and orthogonal transmittance (H ₉₀ ) of the polarizing plate are measured, and the formula: degree of polarization (%) = {(H ₀ −H ₉₀ ) / (H ₀ + H ₉₀ )} ^1/2 × 100. The parallel transmittance (H ₀ ) is a value of transmittance of a parallel laminated polarizing plate produced by superposing two identical polarizing plates so that their absorption axes are parallel to each other. The orthogonal transmittance (H ₉₀ ) is a value of the transmittance of an orthogonal laminated polarizing plate produced by superposing two identical polarizing plates so that their absorption axes are orthogonal to each other. Note that these transmittances are Y values obtained by correcting the visibility with a 2-degree field of view (C light source) of JlSZ 8701-1982.

B-1. Polarizer Any suitable polarizer may be adopted as long as it converts natural light or polarized light into linearly polarized light. The polarizer is preferably a stretched film mainly composed of a polyvinyl alcohol resin containing iodine or a dichroic dye. In the present specification, the “stretched film” refers to a polymer film in which tension is applied to an unstretched film at an appropriate temperature, and molecular orientation is enhanced along the tensile direction.

The thickness of the polarizer may be appropriately selected depending on the purpose. The thickness of the polarizer is preferably 5 μm to 50 μm, and more preferably 10 μm to 30 μm.

The polyvinyl alcohol resin can be obtained by saponifying a vinyl ester polymer obtained by polymerizing a vinyl ester monomer. Examples of the vinyl ester monomers include vinyl formate, vinyl acetate, vinyl propionate, vinyl valelate, vinyl laurate, vinyl stearate, vinyl benzoate, vinyl pivalate, vinyl versatate, and the like.

The saponification degree of the polyvinyl alcohol resin is preferably 95.0 mol% to 99.9 mol%. The saponification degree can be determined according to JISK 6726-1994. By using a polyvinyl alcohol resin having a saponification degree in the above range, a polarizer having excellent durability can be obtained.

As the average degree of polymerization of the polyvinyl alcohol-based resin, an appropriate value can be appropriately selected according to the purpose. The average degree of polymerization is preferably 1200 to 3600. In addition, an average degree of polymerization can be calculated | required according to JISK 6726-1994.

Any appropriate forming method can be adopted as a method for obtaining the polymer film containing the polyvinyl alcohol resin as a main component. Examples of the molding method include the method described in JP 2000-315144 A [Example 1].

The polymer film containing the polyvinyl alcohol resin as a main component preferably contains a polyhydric alcohol as a plasticizer. The polyhydric alcohol is used for the purpose of further improving the dyeability and stretchability of the polarizer. Examples of the polyhydric alcohol include ethylene glycol, glycerin, propylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and trimethylolpropane. These may be used alone or in combination of two or more. The content (weight ratio) of the polyhydric alcohol is preferably more than 0 and 30 with respect to the total solid content 100 of the polyvinyl alcohol resin.

The polymer film containing the polyvinyl alcohol resin as a main component can further contain a surfactant. The surfactant is used for the purpose of further improving the dyeability and stretchability of the polarizer. The surfactant is preferably a nonionic surfactant. Examples of the nonionic surfactant include lauric acid diethanolamide, coconut oil fatty acid diethanolamide, coconut oil fatty acid monoethanolamide, lauric acid monoisopropanolamide, oleic acid monoisopropanolamide, and the like. The content (weight ratio) of the surfactant is preferably more than 0 and 5 or less with respect to the polyvinyl alcohol resin 100.

Any appropriate dichroic material can be adopted. In this specification, “dichroism” refers to optical anisotropy in which light absorption differs in two directions, ie, an optical axis direction and a direction orthogonal thereto. Examples of the dichroic dye include red BR, red LR, red R, pink LB, rubin BL, Bordeaux GS, sky blue LG, lemon yellow, blue BR, blue 2R, navy RY, green LG, violet LB, and violet. B, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Spura Blue G, Spura Blue GL, Spura Orange GL, Direct Sky Blue, Direct First Orange S, First Black, etc. are mentioned.

A commercially available film can be used as it is as the polymer film mainly composed of the polyvinyl alcohol resin used in the present invention. Examples of polymer films based on commercially available polyvinyl alcohol resins include, for example, “Kuraray Vinylon Film” manufactured by Kuraray Co., Ltd., “Toselo Vinylon Film” manufactured by Tosero Co., Ltd., Nippon Synthetic Chemical Industry Product name “Nippon Vinylon Film”, etc., may be mentioned.

An example of a method for manufacturing a polarizer will be described with reference to FIG. FIG. 2 is a schematic view showing the concept of a typical production process of a polarizer used in the present invention. For example, a polymer film 301 mainly composed of a polyvinyl alcohol-based resin is drawn out from the feed-out unit 300, immersed in an iodine aqueous solution bath 310, and tensioned in the film longitudinal direction by rolls 311 and 312 having different speed ratios. While being subjected to swelling and dyeing processes. Next, it is immersed in a bath 320 of an aqueous solution containing boric acid and potassium iodide, and subjected to a crosslinking treatment while tension is applied in the longitudinal direction of the film with rolls 321 and 322 having different speed ratios. The film subjected to the crosslinking treatment is immersed in an aqueous solution bath 330 containing potassium iodide by rolls 331 and 332 and subjected to a water washing treatment. The water-washed film is dried by the drying means 340 so that the moisture content is adjusted to, for example, 10% to 30% and wound up by the winding unit 360. The polarizer 350 can be obtained by stretching the polymer film containing the polyvinyl alcohol resin as a main component to 5 to 7 times the original length through these steps.

B-2. First Protective Layer Referring to FIG. 1, the first protective layer 22 is disposed between the polarizer 21 and the retardation film 30. The first protective layer is used together with the second protective layer for the purpose of preventing the polarizer from contracting and expanding and preventing deterioration due to ultraviolet rays.

As the thickness of the first protective layer, an appropriate value can be appropriately selected according to the purpose. The thickness of the protective layer is preferably 20 μm to 100 μm. By setting the thickness of the first protective layer in the above range, a polarizing plate excellent in mechanical strength and durability can be obtained.

The transmittance of the first protective layer measured with light having a wavelength of 590 nm at 23 ° C. is preferably 90% or more. The theoretical upper limit of the transmittance is 100%, and the realizable upper limit is 96%.

The absolute value (C [590] (m ² / N)) of the photoelastic coefficient of the first protective layer is preferably 1 × 10 ^{−12 to} 100 × 10 ⁻¹² , more preferably 1 × 10 ^{−. 12 to} 60 × 10 ⁻¹² . By using a photoelastic coefficient whose absolute value is in the above range, a polarizing plate in which optical unevenness hardly occurs due to strain can be obtained.

Since the 1st protective layer used for the liquid crystal panel of this invention is arrange | positioned between a polarizer and a liquid crystal cell, the optical characteristic may influence the display characteristic of a liquid crystal display device. Therefore, it is preferable to use the first protective layer having an appropriate retardation value.

In one embodiment, preferably, the first protective layer is substantially optically isotropic. In the present specification, the case of substantially optically isotropic means that the in-plane retardation value (Re [590]) is less than 10 nm and the absolute value of the retardation value in the thickness direction ( | Rth [590] |) is less than 10 nm.

In this specification, Re [590] refers to an in-plane retardation value measured with light having a wavelength of 590 nm at 23 ° C. Here, the “in-plane retardation value” means a retardation value in the film plane when the measurement object is a single film, and a laminate when the measurement object is a laminate. This means the in-plane retardation value of the whole body. Re [590] is expressed by the formula: Re [590] where the refractive indexes in the slow axis direction and the fast axis direction at a wavelength of 590 nm are nx and ny, respectively, and d (nm) is the thickness of the object to be measured. = (Nx−ny) × d. The slow axis means the direction in which the in-plane refractive index is maximum.

When the first protective layer is substantially optically isotropic, Re [590] of the first protective layer is less than 10 nm, preferably 8 nm or less, more preferably 5 nm or less. is there. By setting Re [590] within the above range, a liquid crystal display device with extremely small light leakage and color shift in an oblique direction can be obtained when combined with a retardation film having specific optical characteristics described later.

In this specification, Rth [590] is a thickness direction retardation value measured with light having a wavelength of 590 nm at 23 ° C. Here, “the retardation value in the thickness direction” means the retardation value in the thickness direction of the film when the measurement object is a single film, and when the measurement object is a laminate, It means the retardation value in the thickness direction of the entire laminate. Rth [590] is expressed by the formula: Rth [590] = (nx) where the refractive indices in the slow axis direction and the thickness direction at a wavelength of 590 nm are nx and nz, respectively, and d (nm) is the thickness of the object to be measured. −nz) × d. The slow axis means the direction in which the in-plane refractive index is maximum.

When the first protective layer is substantially optically isotropic, the absolute value of Rth [590] (| Rth [590] |) of the first protective layer is less than 10 nm, preferably Is 8 nm or less, more preferably 5 nm or less. By setting | Rth [590] | in the above range, a liquid crystal display device having extremely small light leakage and color shift in an oblique direction can be obtained when combined with a retardation film having specific optical characteristics described later. .

Re [590] and Rth [590] can be measured using a product name “KOBRA21-ADH” manufactured by Oji Scientific Instruments. In-plane retardation value (Re) at a wavelength of 590 nm at 23 ° C., retardation value measured by tilting 40 degrees with the slow axis as the tilt axis (R40), measurement object thickness (d), and measurement object thickness Using the average refractive index (n0), nx, ny and nz can be obtained by computer numerical calculation from the following formulas (i) to (iii), and then Rth can be calculated by formula (iv). Here, φ and ny ′ are represented by the following equations (v) and (vi), respectively.
Re = (nx−ny) × d (i)
R40 = (nx−ny ′) × d / cos (φ) (ii)
(Nx + ny + nz) / 3 = n0 (iii)
Rth = (nx−nz) × d (iv)
φ = sin ⁻¹ [sin (40 °) / n0] (v)
ny ′ = ny × nz [ny ² × sin ² (φ) + nz ² × cos ² (φ)] ^1/2 (vi)

In another embodiment, preferably, in the first protective layer, the refractive index ellipsoid has a relationship of nx≈ny> nz. Here, nx, ny, and nz are the refractive index in the slow axis direction, the refractive index in the fast axis direction, and the refractive index in the thickness direction, respectively. Ideally, the protective layer in which the refractive index ellipsoid has a relationship of nx≈ny> nz has an optical axis in the normal direction. In this specification, nx≈ny includes not only the case where nx and ny are completely the same, but also the case where nx and ny are substantially the same. Here, “when nx and ny are substantially the same” includes a case where the in-plane retardation value (Re [590]) is less than 10 nm.

When the relationship of the refractive index ellipsoid; nx≈ny> nz is expressed by Re [590] and Rth [590], the first protective layer satisfies the following expressions (1) and (2).
Re [590] <10 nm (1)
10 nm ≦ Rth [590] (2)
However, Re [590] and Rth [590] are an in-plane retardation value and a thickness direction retardation value measured with light having a wavelength of 590 nm at 23 ° C., respectively.

When the refractive index ellipsoid of the first protective layer has a relationship of nx≈ny> nz, Re [590] of the first protective layer is less than 10 nm, preferably 8 nm or less, more preferably Is 5 nm or less. By setting Re [590] within the above range, a liquid crystal display device with extremely small light leakage and color shift in an oblique direction can be obtained when combined with a retardation film having specific optical characteristics described later.

When the refractive index ellipsoid of the first protective layer has a relationship of nx≈ny> nz, Rth [590] of the first protective layer is 10 nm or more, preferably 20 nm to 100 nm, Preferably, it is 30 nm to 80 nm. By setting Rth [590] in the above range, a liquid crystal display device with extremely small oblique light leakage and color shift can be obtained when combined with a retardation film having specific optical characteristics described later.

As the material for forming the first protective layer, an appropriate material can be appropriately adopted. Preferably, the first protective layer is a polymer film containing a cellulose resin. Since the cellulose resin is excellent in adhesiveness with the polarizer, a polarizing plate can be obtained in which the constituent members do not peel off even under high temperature and high humidity.

Arbitrary appropriate things can be employ | adopted for the said cellulose resin. The cellulose-based resin is preferably a cellulose organic acid ester or a cellulose mixed organic acid ester in which part or all of the hydroxyl groups of cellulose are substituted with an acetyl group, a propionyl group and / or a butyl group. Examples of the cellulose organic acid ester include cellulose acetate, cellulose propionate, and cellulose butyrate. Examples of the cellulose mixed organic acid ester include cellulose acetate propionate and cellulose acetate butyrate. The cellulose resin can be obtained, for example, by the method described in JP-A-2001-188128 [0040] to [0041].

A commercially available cellulose resin can be used as it is. Or what carried out arbitrary appropriate polymer modification | denaturation to commercially available resin can be used. Examples of the polymer modification include modifications such as copolymerization, crosslinking, molecular terminals, and stereoregularity. Examples of commercially available cellulose-based resins include cellulose acetate propionate resin manufactured by Daicel Fine Chemical Co., Ltd., cellulose acetate manufactured by EASTMAN, cellulose butyrate manufactured by EASTMAN, cellulose acetate propionate manufactured by EASTMAN, and the like.

The weight average molecular weight (Mw) of the cellulose resin is a value measured by a gel permeation chromatograph (GPC) method using a tetrahydrofuran solvent, preferably 20,000 to 1,000,000, more preferably 25,000. 000-800,000. In addition, the said weight average molecular weight is the value measured by the method as described in an Example. When the weight average molecular weight is in the above range, a material having excellent mechanical strength, good solubility, moldability, and casting operability can be obtained.

The glass transition temperature (Tg) of the cellulose resin is preferably 110 ° C to 185 ° C. If Tg is 110 ° C. or higher, a film having good thermal stability can be easily obtained, and if it is 185 ° C. or lower, molding processability is excellent. The glass transition temperature (Tg) can be determined by the DSC method according to JIS K7121.

Any appropriate molding method can be adopted as a method of obtaining the polymer film containing the cellulose resin. Examples of the molding process include compression molding, transfer molding, injection molding, extrusion molding, blow molding, powder molding, FRP molding, and solvent casting. Preferably, the molding method is a solvent casting method. This is because a polymer film excellent in smoothness and optical uniformity can be obtained.

Specifically, the solvent casting method includes defoaming a concentrated solution (dope) obtained by dissolving a resin composition containing a resin as a main component, an additive, and the like in a solvent, on the surface of an endless stainless belt or a rotating drum, In this method, the film is cast uniformly in a sheet form and the solvent is evaporated. Appropriate conditions can be appropriately selected as conditions employed during film formation depending on the purpose.

The polymer film containing the cellulose-based resin may further contain any appropriate additive. Examples of the additive include a plasticizer, a heat stabilizer, a light stabilizer, a lubricant, an antioxidant, an ultraviolet absorber, a flame retardant, a colorant, an antistatic agent, a compatibilizer, a crosslinking agent, and a thickener. Etc. The content (weight ratio) of the additive can be appropriately set according to the purpose. Preferably, the content (weight ratio) of the additive is more than 0 and 20 or less with respect to 100 parts by weight of the cellulose resin.

A commercially available film can be used as it is for the first protective layer. Alternatively, a commercially available film that has been subjected to secondary processing such as stretching and / or shrinking can be used. As a polymer film containing a commercially available cellulose resin, for example, Fuji Photo Film Co., Ltd. Fujitac series (trade name: ZRF80S, TD80UF, TDY-80UL), Konica Minolta Opto Co., Ltd. trade name “KC8UX2M” Or the like.

B-3. Second Protective Layer Referring to FIG. 1, the second protective layer 23 is disposed on the opposite side of the polarizer 21 from the side having the first protective layer 22. The second protective layer is used together with the first protective layer for the purpose of preventing the polarizer from contracting and expanding and preventing deterioration due to ultraviolet rays.

Any appropriate layer can be adopted as the second protective layer. Preferably, those having a thickness, a transmittance, and a photoelastic coefficient within the range described in the above section C-1 are used.

As a material for forming the second protective layer, an appropriate material can be appropriately adopted. Preferably, the second protective layer is a polymer film containing a cellulose resin. The polymer film containing the cellulose resin is preferably the same as that described in the section B-2.

The second protective layer used in the liquid crystal panel of the present invention is disposed on the outside (viewing side or backlight side) of the liquid crystal cell. For example, in the first polarizing plate, the second protective layer can be disposed on the outermost surface on the viewing side. Alternatively, in the second polarizing plate, the second protective layer may be disposed on an upper part of the prism sheet that has been subjected to uneven processing. Therefore, the second protective layer preferably further includes a surface treatment layer on the outer surface (the side opposite to the side including the polarizer).

The surface treatment layer can be appropriately treated according to the purpose. Examples of the surface treatment layer include treatment layers such as hard coat treatment, antistatic treatment, antireflection treatment (also referred to as antireflection treatment), and diffusion treatment (also referred to as antiglare treatment). These surface treatment layers are used for the purpose of preventing the screen from being soiled or damaged, or preventing the display image from becoming difficult to see due to the reflection of indoor fluorescent light or sunlight on the screen. In general, the surface treatment layer is formed by fixing a treatment agent for forming the treatment layer on the surface of a base film. The base film may also serve as the second protective layer. Further, the surface treatment layer may have a multilayer structure in which, for example, a hard coat treatment layer is laminated on an antistatic treatment layer.

As the second protective layer, a commercially available polymer film provided with a surface treatment layer can be used as it is. Alternatively, a commercially available polymer film can be used after any surface treatment. Examples of commercially available diffusion treatment (anti-glare treatment) include AG150, AGS1, AGS2, and AGT1 manufactured by Nitto Denko Corporation. Examples of commercially available antireflection treatment (anti-reflection treatment) include ARS and ARC manufactured by Nitto Denko Corporation. Examples of the commercially available film subjected to the hard coat treatment and the antistatic treatment include “KC8UX-HA” manufactured by Konica Minolta Opto Co., Ltd. Examples of the commercially available surface treatment layer subjected to the antireflection treatment include ReaLook series manufactured by NOF Corporation.

B-4. Adhesive layer In the polarizing plate, the adhesive layer provided for adhering the first protective layer and the second protective layer to the polarizer may be any appropriate adhesive, pressure-sensitive adhesive, and / or anchor coating agent. Can be employed.

The thickness of the adhesive layer can be appropriately selected depending on the purpose. The thickness of the adhesive layer is preferably 0.01 μm to 50 μm. By setting the thickness of the adhesive layer in the above range, the polarizer and the protective layer to be joined do not float or peel off, and a practically sufficient adhesive force and adhesive time can be obtained.

The material for forming the adhesive layer is preferably a water-soluble adhesive mainly composed of a polyvinyl alcohol resin. This is because the adhesive property between the polarizer and the protective layer is excellent, and the workability, productivity and economy are excellent. A commercially available adhesive can be used as it is as the water-soluble adhesive mainly composed of the polyvinyl alcohol resin. Or a solvent and an additive can also be mixed and used for a commercially available adhesive agent. As a water-soluble adhesive mainly composed of a commercially available polyvinyl alcohol resin, for example, GOHSENOL series (trade names “NH-18S, GH-18S, T-330, etc.”) manufactured by Nippon Synthetic Chemical Industry Co., Ltd. And Goseifamer series (trade names “Z-100, Z-200, Z-210, etc.”) manufactured by the same company.

The adhesive layer may be obtained by crosslinking a composition obtained by further blending a crosslinking agent with the water-soluble adhesive. Any appropriate crosslinking agent may be employed depending on the purpose. Examples of the crosslinking agent include amine compounds, aldehyde compounds, methylol compounds, epoxy compounds, isocyanate compounds, and polyvalent metal salts. A commercially available crosslinking agent can be used as it is. Commercially available cross-linking agents include amine compounds manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name “metaxylene diamine”, aldehyde compounds manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name “Glyoxal”, and methylol compounds manufactured by Dainippon Ink, Inc. The trade name “Watersol” and the like can be mentioned.

C. Retardation film The retardation film used in the present invention is a stretched film containing a norbornene-based resin. Since the stretched film containing the norbornene-based resin has a small absolute value of the photoelastic coefficient, for example, even if distortion occurs in the laminated film due to stress due to expansion and contraction of the polarizer, the retardation value fluctuates and optical Is less likely to cause unevenness. As a result, a liquid crystal display device excellent in display uniformity can be obtained.

The refractive index ellipsoid of the retardation film preferably has a relationship of nx> nz> ny. A retardation film having such a refractive index ellipsoidal relationship can be arranged on one side or both sides of a liquid crystal cell to greatly reduce oblique light leakage and oblique color shift of a liquid crystal display device. it can. In general, in a liquid crystal display device in which two polarizing plates are arranged on both sides of a liquid crystal cell so that their absorption axis directions are orthogonal to each other, light leaks from an oblique direction. Specifically, when the long side of the liquid crystal panel is set to 0 °, the amount of light leakage tends to be maximized in the oblique 45 ° azimuth and 135 ° azimuth. When the retardation film having the above-described refractive index ellipsoidal relationship is used for the laminated film of the present invention, a liquid crystal display device in which light leakage in an oblique direction is remarkably smaller than that of a conventional liquid crystal display device. Can be obtained.

When the relationship of the refractive index ellipsoid; nx>nz> ny is expressed by Re [590] and Rth [590], the retardation film satisfies the following formula (3).
10 nm ≦ Rth [590] <Re [590] (3)
However, Re [590] and Rth [590] are an in-plane retardation value and a thickness direction retardation value measured with light having a wavelength of 590 nm at 23 ° C., respectively.

Conventionally, a retardation film containing a norbornene resin and having a refractive index ellipsoid having a relationship of nx> nz> ny has not been obtained. This is because a polymer film containing a norbornene-based resin is less likely to generate a retardation value by stretching than other resins, or the film itself is fragile, and stretching is difficult. Furthermore, in order to make the refractive index (nz) in the thickness direction of the film larger than one in-plane refractive index (ny), a large stress must be applied to the film, and the production of such a retardation film is required. Made it more difficult. According to the present invention, a retardation film having a relationship of nx> nz> ny can be actually obtained using a stretched film containing a norbornene-based resin by a production method using a specific shrinkable film.

Referring to FIG. 1, the retardation film 30 is disposed between the first protective layer 22 disposed on one side of the polarizing plate 20 and the first pressure-sensitive adhesive layer 41. Preferably, the slow axis direction of the retardation film 30 is substantially parallel, substantially orthogonal, or substantially 45 ° with the absorption axis direction of the polarizer 21. More preferably, the slow axis direction of the retardation film 30 is substantially orthogonal to the absorption axis direction of the polarizer 21. In this way, by using the retardation film in a specific positional relationship, a liquid crystal display device with even smaller light leakage in the oblique direction can be obtained. In this specification, “substantially parallel” includes the case where the angle formed by the slow axis direction of the retardation film 30 and the absorption axis direction of the polarizer 21 is 0 ° ± 2.0 °. Preferably, it is 0 ° ± 1.0 °, and more preferably 0 ° ± 0.5 °. “Substantially orthogonal” includes the case where the angle formed by the slow axis direction of the retardation film 30 and the absorption axis direction of the polarizer 21 is 90 ° ± 2.0 °, preferably 90 °. It is ± 1.0 °, and more preferably 90 ° ± 0.5 °. Further, “substantially 45 °” includes the case where the angle formed by the slow axis direction of the retardation film 30 and the absorption axis direction of the polarizer 21 is 45 ° ± 2.0 °, preferably Is 45 ° ± 1.0 °, more preferably 45 ° ± 0.5 °. Liquid crystal display in which the smaller the deviation of the angle between the slow axis direction of the retardation film and the absorption axis direction of the polarizer (from 0 °, 90 °, or 45 °), the smaller the light leakage in the oblique direction. A device can be obtained.

The thickness of the retardation film can be appropriately selected depending on the purpose. The thickness of the retardation film is preferably 20 μm to 200 μm. By setting the thickness of the retardation film within the above range, a target retardation value can be obtained, and a retardation film excellent in mechanical strength and durability can be obtained.

The transmittance of the retardation film measured with light having a wavelength of 590 nm at 23 ° C. is preferably 90% or more. The theoretical upper limit of the transmittance is 100%, and the realizable upper limit is 96%.

The absolute value (C [590] (m ² / N)) of the photoelastic coefficient of the retardation film is preferably 1 × 10 ⁻¹² to 10 × 10 ⁻¹² , more preferably 1 × 10 ⁻¹² to 8 × 10 ⁻¹² , particularly preferably 1 × 10 ^{−12 to} 6 × 10 ⁻¹² . By using a film having an absolute value of the photoelastic coefficient in the above range, a retardation film that hardly causes optical unevenness due to strain can be obtained.

One or both sides of the retardation film used in the present invention may be subjected to surface modification treatment. Any appropriate method can be adopted as the surface modification treatment. For example, the surface modification treatment may be a dry treatment or a wet treatment. Specific examples of the dry treatment include discharge treatment such as corona treatment and glow discharge treatment, flame treatment, ozone treatment, UV ozone treatment, ionization active ray treatment such as ultraviolet ray treatment and electron beam treatment. The surface modification treatment (dry treatment) suitable for the retardation film is preferably corona treatment. In this specification, “corona treatment” refers to a corona in which air between electrodes is dielectrically broken and ionized by applying a high frequency and high voltage between a grounded dielectric roll and an insulated electrode. This means that the film surface is modified by allowing the film to pass through the discharge.

Examples of the wet treatment include alkali treatment and anchor coat treatment. In the present specification, “alkali treatment” refers to a treatment in which the film surface is modified by immersing the film in an alkali treatment solution in which a basic substance is dissolved in water or an organic solvent. “Anchor coating treatment” refers to a treatment in which an anchor coating agent is applied in advance to the laminated surface of the film for the purpose of improving the adhesion between the film and the pressure-sensitive adhesive layer. The surface modification treatment (wet treatment) suitable for the retardation film is preferably an anchor coat treatment. The anchor coat agent used for the anchor coat treatment preferably contains polymers having an amino group in the molecule, and particularly preferably contains polyethyleneimine.

C-1. Material for Forming Retardation Film Any appropriate norbornene-based resin can be adopted as the retardation film. The norbornene-based resin is preferably a resin that is excellent in transparency, mechanical strength, thermal stability, moisture shielding properties, and the like, and hardly causes optical unevenness due to strain.

In this specification, the norbornene-based resin refers to a (co) polymer obtained by using a norbornene-based monomer having a norbornene ring as a part or all of a starting material (monomer). In the present specification, “(co) polymer” means a homopolymer or a copolymer (copolymer).

In the norbornene-based resin, a norbornene-based monomer having a norbornene ring (having a double bond in the norbornane ring) is used as a starting material. In the state of the (co) polymer, the norbornene-based resin may or may not have a norbornane ring in the structural unit. The norbornene-based resin having a norbornane ring as a structural unit in the state of a (co) polymer is, for example, tetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] dec-3-ene, 8-methyltetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] Dec-3-ene, 8-methoxycarbonyltetracyclo [4.4.1 ^2,5 . 1 ^7,10 . 0] Dec-3-ene and the like. A norbornene-based resin having no norbornane ring as a structural unit in the (co) polymer state is, for example, a (co) polymer obtained using a monomer that becomes a 5-membered ring by cleavage. Examples of the monomer that becomes a 5-membered ring by cleavage include norbornene, dicyclopentadiene, 5-phenylnorbornene, and derivatives thereof. When the norbornene-based resin is a copolymer, the arrangement state of the molecules is not particularly limited, and may be a random copolymer, a block copolymer, or a graft copolymer. It may be.

As said norbornene-type resin, a commercially available thing can be used as it is. Or what carried out arbitrary appropriate polymer modification | denaturation to commercially available norbornene-type resin can be used. Examples of commercially available norbornene resins include Arton series (trade name: ARTON FLZR50, ARTON FLZR70, ARTONFLZL100, ARTON F5023, ARTONFX4726, ARTON FX4727, ARTOND4531, ARTON D4532 etc.) manufactured by JSR Co., Ltd. ZEONOR series (trade names; ZEONOR 750R, ZEONOR 1020R, ZEONOR1600, etc.), Apel series (APL8008T, APL6509T, APL6011T, APL6013T, APL6015T, APL5014T, etc.) manufactured by Mitsui Chemicals, COPA resin manufactured by TICONA; Etc.

Examples of the norbornene resin include (A) a resin obtained by hydrogenating a ring-opening (co) polymer of a norbornene monomer, and (B) a resin obtained by addition (co) polymerization of a norbornene monomer. The ring-opening copolymer of the norbornene-based monomer is a resin obtained by hydrogenating a ring-opening copolymer of one or more norbornene-based monomers and α-olefins, cycloalkenes, and / or non-conjugated dienes. Include. The resin obtained by addition copolymerization of the norbornene monomer includes a resin obtained by addition copolymerization of one or more norbornene monomers with α-olefins, cycloalkenes and / or non-conjugated dienes. The norbornene-based resin is preferably a resin obtained by hydrogenating a ring-opening (co) polymer of (A) norbornene-based monomer. This is because a retardation film having excellent molding processability and a large retardation value at a low draw ratio can be obtained.

A resin obtained by hydrogenating the ring-opening (co) polymer of the norbornene monomer is subjected to a metathesis reaction of the norbornene monomer or the like to obtain a ring-opening (co) polymer. It can be obtained by hydrogenation. Specifically, for example, NTS Co., Ltd. “Development and application technology of optical polymer materials” p. 103-p. 111 (2003 edition), the method described in paragraphs [0059] to [0060] of JP-A-11-116780, and the paragraphs [0035] to [0037] of JP-A-2001-350017. And the method described in paragraph [0053] of JP-A-2005-008698. The resin obtained by addition (co) polymerization of the norbornene monomer can be obtained, for example, by the method described in Example 1 of JP-A No. 61-292601.

The weight average molecular weight (Mw) of the norbornene resin is preferably 20,000 to 500,000, more preferably 30 as measured by a gel permeation chromatograph (GPC) method using a tetrahydrofuran solvent. , 000-200,000. The said weight average molecular weight is the value measured by the method as described in an Example. When the weight average molecular weight is in the above range, a material having excellent mechanical strength, good solubility, moldability, and casting operability can be obtained.

The glass transition temperature (Tg) of the norbornene-based resin is preferably 110 ° C. to 185 ° C., more preferably 120 ° C. to 170 ° C., and particularly preferably 125 ° C. to 150 ° C. If Tg is 110 ° C. or higher, a film having good thermal stability is easily obtained, and if it is 185 ° C. or lower, in-plane and thickness direction retardation values are easily controlled by stretching. The glass transition temperature (Tg) can be determined by a DSC method according to JIS K7121.

As a method for obtaining the polymer film containing the norbornene-based resin, any appropriate forming method can be adopted. Examples of the forming method include the method described in the section B-2. Preferably, the molding method is a solvent casting method. This is because a polymer film excellent in smoothness and optical uniformity can be obtained.

The polymer film containing the norbornene-based resin may further contain any appropriate additive. Examples of the additive include a plasticizer, a heat stabilizer, a light stabilizer, a lubricant, an antioxidant, an ultraviolet absorber, a flame retardant, a colorant, an antistatic agent, a compatibilizer, a crosslinking agent, and a thickener. Etc. The content (weight ratio) of the additive is preferably more than 0 and 10 or less with respect to the norbornene-based resin 100.

The polymer film containing the norbornene resin may be obtained from a resin composition containing a norbornene resin and another resin. Any appropriate resin may be selected as the other resin. The other resin is preferably a styrene resin. The styrenic resin can be used to adjust the wavelength dispersion value and photoelastic coefficient of the retardation film. The content (weight ratio) of the other resin is preferably more than 0 and 30 or less with respect to the norbornene-based resin 100.

As the polymer film containing the norbornene resin, a commercially available film can be used as it is. Alternatively, a commercially available film that has been subjected to secondary processing such as stretching and / or shrinking can be used. As a polymer film containing a commercially available norbornene-based resin, for example, Arton series (trade name: ARTON F, ARTON FX, ARTON D) manufactured by JSR Corporation, or ZEONOR series (trade name: ZEONOR Corporation) manufactured by Optes Co., Ltd. ZF14, ZEONOR ZF16) and the like.

C-2. Optical Properties of Retardation Film An appropriate value can be selected as appropriate for Re [590] of the above retardation film according to the purpose. Re [590] of the retardation film is 10 nm or more, preferably 80 nm to 350 nm, more preferably 120 nm to 350 nm, and further preferably 160 nm to 280 nm. By setting Re [590] in the above range, a liquid crystal display device with extremely small light leakage in the oblique direction and color shift in the oblique direction can be obtained.

An appropriate value of Re [590] of the retardation film can be selected depending on the value of Rth [590] of the first protective layer. Preferably, Re [590] of the retardation film has a total of Re [590] and Rth [590] of the first protective layer (Re [590] + Rth [590]) of 220 nm to 300 nm. Is set as follows. For example, when the first protective layer is substantially optically isotropic and | Rth [590] | is less than 10 nm, Re [590] of the retardation film is preferably 250 nm to 310 nm. When Rth [590] of the first protective layer is 40 nm, Re [590] of the retardation film is preferably 180 nm to 260 nm. When Rth [590] of the first protective layer is 60 nm, Re [590] of the retardation film is preferably 160 nm to 240 nm. When Rth [590] of the first protective layer is 100 nm, Re [590] of the retardation film is preferably 120 nm to 200 nm.

The wavelength dispersion value (D) of the retardation film is preferably 0.90 to 1.10, more preferably 0.95 to 1.05, and particularly preferably 0.98 to 1.02. . The chromatic dispersion value (D) is a value calculated from the formula: Re [480] / Re [590], and Re [480] and Re [590] are light at wavelengths of 480 nm and 590 nm at 23 ° C., respectively. This is the in-plane retardation value measured in (1). By using a retardation film having a wavelength dispersion value (D) in the above range, a liquid crystal display device can be obtained in which the color shift in the oblique direction is much smaller than that of a conventional liquid crystal display device.

The Nz coefficient of the retardation film is preferably 0.1 to 0.7, more preferably 0.2 to 0.6, and particularly preferably 0.25 to 0.55. Most preferably, it is 0.35-0.55. The Nz coefficient is a value calculated from the formula: Rth [590] / Re [590], and Re [590] and Rth [590] are in-plane measured with light having a wavelength of 590 nm at 23 ° C., respectively. The phase difference value and the thickness direction retardation value. By setting the Nz coefficient in the above range, a liquid crystal display device with extremely small light leakage in the oblique direction and color shift in the oblique direction can be obtained.

As the Nz coefficient of the retardation film, an appropriate value can be selected depending on the value of Rth [590] of the first protective layer. For example, when the first protective layer is substantially optically isotropic and | Rth [590] | is less than 10 nm, the Nz coefficient of the retardation film is preferably 0.4 to 0.6. When Rth [590] of the first protective layer is 40 nm, the Nz coefficient of the retardation film is preferably 0.3 to 0.5. Alternatively, when Rth [590] of the first protective layer is 60 nm, the Nz coefficient of the retardation film is preferably 0.2 to 0.4. Alternatively, when Rth [590] of the first protective layer is 100 nm, the Nz coefficient of the retardation film is preferably 0.1 to 0.3.

As Rth [590] of the retardation film, an appropriate value can be appropriately selected according to the Nz coefficient. Preferably, Rth [590] of the retardation film is smaller than Re [590], preferably 10 nm to 200 nm, more preferably 20 nm to 180 nm, and further preferably 30 nm to 140 nm. By setting Rth [590] in the above range, a liquid crystal display device with extremely small light leakage in the oblique direction and color shift in the oblique direction can be obtained.

C-3. Production method of retardation film The retardation film is obtained by, for example, pasting a shrinkable film on both sides of a polymer film containing a norbornene-based resin, and heating and stretching the film by a longitudinal uniaxial stretching method using a roll stretching machine. Can do. The shrinkable film is used for imparting a shrinkage force in a direction perpendicular to the stretching direction at the time of heat stretching and increasing a refractive index (nz) in the thickness direction. As a method for bonding the shrinkable film to both surfaces of the polymer film, an appropriate method can be appropriately employed. Preferably, a method in which a pressure-sensitive adhesive layer containing an acrylic pressure-sensitive adhesive is provided between the polymer film and the shrinkable film for adhesion is preferable from the viewpoint of excellent productivity, workability, and economic efficiency.

An example of a method for producing the retardation film will be described with reference to FIG. FIG. 3 is a schematic diagram showing the concept of a typical production process of the retardation film used in the present invention. For example, the polymer film 402 containing a norbornene-based resin is fed from the first feeding unit 401 and fed from the second feeding unit 403 to both surfaces of the polymer film 402 by the laminate rolls 407 and 408. The shrinkable film 404 including the pressure-sensitive adhesive layer and the shrinkable film 406 including the pressure-sensitive adhesive layer fed out from the third feeding portion 405 are bonded together. The polymer film having the shrinkable film attached on both sides is given a tension in the longitudinal direction of the film by rolls 410, 411, 412 and 413 having different speed ratios while being held at a constant temperature by the heating means 409 ( At the same time, the film is subjected to a stretching treatment while being given a tension in the thickness direction by the shrinkable film. The stretched film 418 is peeled off at the first winding portion 414 and the second winding portion 415 together with the shrinkable films 404 and 406 together with the adhesive layer, and wound at the third winding portion 419. It is done.

The shrinkable film is preferably a stretched film such as a biaxially stretched film or a uniaxially stretched film. The shrinkable film can be obtained, for example, by stretching an unstretched film formed into a sheet by an extrusion method in the longitudinal and / or transverse direction at a predetermined magnification with a simultaneous biaxial stretching machine or the like. The molding and stretching conditions can be appropriately selected depending on the composition, type and purpose of the resin used.

Examples of the material used for the shrinkable film include polyester, polystyrene, polyethylene, polypropylene, polyvinyl chloride, and polyvinylidene chloride. Preferably, the shrinkable film is a biaxially stretched film containing polypropylene. Since such a shrinkable film is excellent in shrinkage uniformity and heat resistance, a target retardation value can be obtained, and a retardation film excellent in optical uniformity can be obtained.

In one embodiment, preferably, the shrinkable film has a shrinkage ratio in the film longitudinal direction at 140 ° C .: S ¹⁴⁰ [MD] of 5.0% to 7.7%, and the film at 140 ° C. Shrinkage ratio in the width direction: S ¹⁴⁰ [TD] is 10.0% to 15.5%. More preferably, the shrinkable film has S ¹⁴⁰ [MD] of 5.5% to 7.0% and S ¹⁴⁰ [TD] of 11.5% to 14.5%.

In another embodiment, preferably, the shrinkable film has a film longitudinal shrinkage at 160 ° C .: S ¹⁶⁰ [MD] of 15.5% to 23.5%, and a film at 140 ° C. Shrinkage ratio in the width direction: S ¹⁶⁰ [TD] is 36.5% to 54.5%. More preferably, the shrinkable film has an S ¹⁶⁰ [MD] of 17.5% to 21.5% and an S ¹⁶⁰ [TD] of 40.0% to 50.0%. By setting the shrinkage rate at each temperature of the shrinkable film within the above range, a retardation film having a target retardation value and excellent in uniformity can be obtained.

In one embodiment, the difference between the shrinkage in the width direction and the shrinkage in the longitudinal direction at 140 ° C. of the shrinkable film: ΔS ¹⁴⁰ = S ¹⁴⁰ [TD] −S ¹⁴⁰ [MD] is preferably 5.0. % To 7.7%, more preferably 5.7% to 7.0%. In another embodiment, the difference between the shrinkage in the width direction and the shrinkage in the longitudinal direction at 160 ° C. of the shrinkable film: ΔS ¹⁶⁰ = S ¹⁶⁰ [TD] −S ¹⁶⁰ [MD] is preferably 20.5. % To 31.5%, more preferably 23.0% to 28.5%. If the shrinkage rate in the MD direction is large, in addition to stretching tension, the shrinking force of the shrinkable film may be applied to a stretching machine, making uniform stretching difficult. By setting the shrinkage rate of the shrinkable film in the above range, uniform stretching can be performed without applying an excessive load to equipment such as a stretching machine.

The shrinkage stress in the width direction at 140 ° C. of the shrinkable film: T ¹⁴⁰ [TD] is preferably 0.50 N / 2 mm to 0.80 N / 2 mm, more preferably 0.58 N / 2 mm to 0.72 N /. 2 mm. The shrinkage stress in the width direction at 150 ° C. of the shrinkable film: T ¹⁵⁰ [TD] is preferably 0.60 N / 2 mm to 0.90 N / 2 mm, more preferably 0.67 N / 2 mm to 0.83 N /. 2 mm. By setting the shrinkage rate of the shrinkable film in the above range, a retardation film having a target retardation value and excellent in optical uniformity can be obtained.

The shrinkage rates S [MD] and S [TD] can be determined according to the heating shrinkage rate A method of JISZ 1712-1997 (however, the heating temperature is 140 ° C (or 160 ° C) instead of 120 ° C). The difference is that a load of 3 g was applied to the test piece). Specifically, five test pieces each having a width of 20 mm and a length of 150 mm were taken from the vertical [MD] and horizontal [TD] directions, and a test piece with a mark at a distance of about 100 mm was prepared at the center of each. To do. The test piece is suspended vertically in an air circulation type drying oven maintained at a temperature of 140 ° C. ± 3 ° C. (or 160 ° C. ± 3 ° C.) under a load of 3 g, heated for 15 minutes, and then taken out. Further, after being left in the standard state (room temperature) for 30 minutes, the distance between the gauge points is measured using a caliper specified in JIS B 7507, and the average value of the five measured values is obtained. Shrinkage is expressed by the following equation: S (%) = [[Distance between gauge points before heating (mm) −Distance between gauge points after heating (mm)] / Distance between gauge points before heating (mm)] × 100 Can be calculated.

The shrinkable film can be used for general packaging, food packaging, pallet packaging, shrinkage labels, cap seals, and electrical insulation, as long as it satisfies the properties such as shrinkage. A commercially available shrinkable film can be appropriately selected and used. These commercially available shrinkable films may be used as they are, or after being subjected to secondary processing such as stretching treatment or shrinkage treatment. Commercially available shrinkable films include, for example, Oji Paper Co., Ltd. Alpha Series (trade name; Alfan P, Alfan S, Alfan H, etc.), Gunze Co., Ltd. Fancy Top Series (trade name; Fancy) Top EP1, Fancy Top EP2, etc.), Toray Industries, Inc. Trefan BO series (trade name; 2570, 2873, 2500, 2554, M114, M304, etc.), Santox Corporation Santox-OP series (trade name; PA20, PA21, PA30, etc.) and Tosero OP series (trade names; OPU-0, OPU-1, OPU-2, etc.) and the like.

The temperature in the stretching oven (also referred to as stretching temperature) when the laminate of the polymer film containing the norbornene-based resin and the shrinkable film is heated and stretched is the target retardation value, the polymer film used. It can be appropriately selected according to the type and thickness. The stretching temperature is preferably Tg + 1 ° C. to Tg + 30 ° C. with respect to the glass transition temperature (Tg) of the polymer film. By setting it as said temperature range, the retardation value of a retardation film becomes easy to become uniform, and it becomes difficult to crystallize (white turbidity) a film. Specifically, the stretching temperature is usually 110 ° C to 185 ° C. The glass transition temperature (Tg) can be determined by a DSC method according to JIS K 7121-1987.

Furthermore, the stretching ratio (stretching ratio) when stretching a laminate of a polymer film containing a norbornene-based resin and a shrinkable film depends on the target retardation value, the type and thickness of the polymer film used, etc. Depending on the case, it can be selected appropriately. The draw ratio is usually more than 1 and less than 2 times the original length. The feeding speed during stretching is usually 1 m / min to 20 m / min from the viewpoint of mechanical accuracy and stability of the stretching apparatus. If it is said extending | stretching conditions, the target retardation value will be obtained and the retardation film excellent in the optical uniformity may be obtained.

D. 1st adhesive layer The 1st adhesive layer used for this invention bridge | crosslinks the composition which mix | blended at least the (meth) acrylate type | system | group (co) polymer and the crosslinking agent which has a peroxide as a main component. A pressure-sensitive adhesive that can be obtained. In the present invention, the “pressure-sensitive adhesive” refers to a viscoelastic substance that exhibits an adhesive force that can be sensed by pressure contact at room temperature.

Referring to FIG. 1, the first pressure-sensitive adhesive layer 41 is disposed on the side opposite to the side of the retardation film 30 that includes the polarizing plate 20. The first pressure-sensitive adhesive layer is used for fixing the laminated film of the present invention to, for example, a liquid crystal cell of a liquid crystal display device. Such an adhesive layer can be firmly adhered to a stretched film (retardation film) containing a norbornene resin. In addition, a practically sufficient adhesive force and bonding time can be obtained with respect to the substrate (glass plate) of the liquid crystal cell without peeling or bubbles even in a high temperature and high humidity environment. On the other hand, when peeling from the liquid crystal cell, the pressure-sensitive adhesive layer and the retardation film do not remain on the surface of the liquid crystal cell, and can be peeled with a light force.

Conventionally, a pressure-sensitive adhesive layer that exhibits strong adhesion to stretched films containing norbornene-based resins and moderate adhesion and light peelability to liquid crystal cell substrates (glass plates) is obtained. It was not done. This is because a stretched film containing a norbornene resin has fewer polar groups that can act on the pressure-sensitive adhesive than other resins such as a polycarbonate resin. Furthermore, as described above, the stretched film containing a norbornene-based resin is more difficult to peel because the film itself is brittle. According to the present invention, by using a pressure-sensitive adhesive that can be obtained by crosslinking a specific composition, it is possible to obtain a laminated film excellent in adhesiveness and light peelability.

D-1. Various physical properties of the first pressure-sensitive adhesive layer The thickness of the first pressure-sensitive adhesive layer can be appropriately selected according to the purpose. The thickness of the first pressure-sensitive adhesive layer is preferably 2 μm to 50 μm, more preferably 2 μm to 40 μm, and particularly preferably 5 μm to 35 μm. By setting the thickness of the first pressure-sensitive adhesive layer in the above range, a laminated film having an appropriate adhesive force and excellent in light peelability can be obtained.

The transmittance of the first pressure-sensitive adhesive layer measured with light having a wavelength of 590 nm at 23 ° C. is preferably 90% or more. The theoretical upper limit of the transmittance is 100%, and the realizable upper limit is 96%.

Re [590] of the first pressure-sensitive adhesive layer is preferably less than 2 nm, and more preferably less than 1 nm. Rth [590] of the first pressure-sensitive adhesive layer is preferably less than 2 nm, more preferably less than 1 nm.

The adhesive force (F _1A ) to the glass plate at 23 ° C. of the first pressure-sensitive adhesive layer is preferably 2 N / 25 mm to 10 N / 25 mm, more preferably 3 N / 25 mm to 9 N / 25 mm, and particularly preferably. 3N / 25mm to 8N / 25mm, most preferably 4N / 25mm to 6N / 25mm. The above adhesive strength is the adhesive strength when a 25 mm wide laminated film is pressed once on a glass plate with a 2 kg roller and cured at 23 ° C. for 1 hour, and then peeled off at 300 mm / min in a 90 degree direction. is there.

The throwing force (F _1B ) on the retardation film at 23 ° C. of the first pressure-sensitive adhesive layer is preferably 10 N / 25 mm to 40 N / 25 mm, more preferably 14 N / 25 mm to 40 N / 25 mm, and particularly preferably. Is 17 N / 25 mm to 35 N / 25 mm. The throwing force is such that a laminate of a 25 mm-wide pressure-sensitive adhesive layer and a retardation film is subjected to one-way reciprocating with a 2 kg roller on a treated surface of a polyethylene terephthalate film on which indium tin oxide (ITO) is vapor-deposited. The adhesive strength when the polyethylene terephthalate film is peeled off at 300 mm / min in the direction of 180 degrees together with the pressure-sensitive adhesive layer after being cultivated for 1 hour.

In the laminated film of the present invention, the relationship between the adhesive force (F _1A ) of the first pressure-sensitive adhesive layer to the glass plate at 23 ° C. and the anchoring force (F _1B ) to the retardation film at 23 ° C. is preferably F _1A <F _1B . Furthermore, the difference between the anchoring force and the adhesive force of the first pressure-sensitive adhesive layer; (F _1B −F _1A ) is preferably 5 N / 25 mm or more, more preferably 5 N / 25 mm to 37 N / 25 mm, Particularly preferred is 8 N / 25 mm to 31 N / 25 mm, and most preferred is 16 N / 25 mm to 30 N / 25 mm. By making the relationship between F _1A and F _1B as described above, a pressure-sensitive adhesive layer or retardation film does not remain on the surface of the liquid crystal cell, and a laminated film excellent in light peelability can be obtained.

The first pressure-sensitive adhesive layer may further contain any appropriate additive. Examples of the additive include metal powder, glass fiber, glass beads, silica, and a filler. Moreover, the said 1st adhesive layer may contain the transfer substance (for example, residual solvent, additive, oligomer, etc.) from an adjacent layer. The content (weight ratio) of the additive is preferably more than 0 and 10 or less with respect to the total solid content 100 of the first pressure-sensitive adhesive layer. In addition, the content (weight ratio) of the transition material is preferably more than 0 and 5 or less with respect to the total solid content 100 of the first pressure-sensitive adhesive layer.

D-2. The pressure-sensitive adhesive forming the first pressure-sensitive adhesive layer The pressure-sensitive adhesive forming the first pressure-sensitive adhesive layer was blended with at least a (meth) acrylate-based (co) polymer and a crosslinking agent mainly composed of peroxide. It can be obtained by crosslinking the composition. In the present specification, “crosslinking” means that a polymer is chemically crosslinked to form a three-dimensional network structure.

D-3. Preparation of raw material composition (first adhesive layer)
As the (meth) acrylate-based (co) polymer, an appropriate one can be appropriately employed depending on the purpose. The said (meth) acrylate type | system | group (co) polymer says the (co) polymer obtained using a (meth) acrylate type monomer. When the polymer is a copolymer, the arrangement state of the molecules is not particularly limited, and may be a random copolymer, a block copolymer, or a graft copolymer. May be. The molecular arrangement state of the (meth) acrylate-based (co) polymer is preferably a random copolymer.

In the present specification, the “(meth) acrylate-based (co) polymer” means an acrylate-based polymer or a methacrylate-based polymer when the polymer is a homopolymer, and when the polymer is a copolymer, Acrylate copolymer synthesized from two or more acrylate monomers, methacrylate copolymer synthesized from two or more methacrylate monomers, or synthesized from one or more acrylate monomers and one or more methacrylate monomers Means a copolymer. Further, “(meth) acrylate monomer” means an acrylate monomer or a methacrylate monomer.

The (meth) acrylate-based (co) polymer can be obtained by any appropriate polymerization method. Examples of the polymerization method include a solution polymerization method, a bulk polymerization method, and a suspension polymerization method. In the present invention, the polymerization method is preferably a solution polymerization method. Specifically, in the solution polymerization method, for example, a polymerization initiator such as azobisisobutyronitrile is added to a solution in which a monomer is dissolved in a solvent in an amount of 0.01 to 0. In this method, 2 parts by weight is added, the temperature of the solution is set to 50 to 70 ° C., and the reaction is performed for 8 to 30 hours in a nitrogen atmosphere. Such a polymerization method has an advantage that the polymerization temperature can be adjusted with high accuracy. Furthermore, there is an advantage that the polymer solution after polymerization can be easily taken out from the reaction vessel.

The weight average molecular weight (Mw) of the (meth) acrylate-based (co) polymer can be appropriately set to an appropriate value. Preferably, the weight average molecular weight (Mw) is a value measured by a gel permeation chromatograph (GPC) method using a tetrahydrofuran solvent, preferably 1,000,000 or more, more preferably 1,200, 000 to 3,000,000, particularly preferably 1,200,000 to 2,500,000. The said weight average molecular weight (Mw) can be suitably adjusted suitably with the kind of solvent, superposition | polymerization temperature, an additive, etc.

Preferably, the (meth) acrylate (co) polymer is a (co) polymer obtained using a (meth) acrylate monomer having a linear or branched alkyl group having 1 to 10 carbon atoms. Examples of the (meth) acrylate monomer having a linear or branched alkyl group having 1 to 10 carbon atoms include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and n-butyl (meth). Acrylate, iso-butyl (meth) acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, iso-pentyl (meth) acrylate, n-hexyl (meth) acrylate, iso-hexyl (meth) acrylate, n-heptyl (meth) acrylate, iso-heptyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, iso-octyl (meth) acrylate, n-nonyl (meth) acrylate, iso- Nonyl (meth) a Relate, n- decyl (meth) acrylate, iso- decyl (meth) acrylate.

More preferably, the (meth) acrylate-based (co) polymer has a (meth) acrylate-based monomer having a linear or branched alkyl group having 1 to 8 carbon atoms, and at least one hydrogen atom is substituted with a hydroxyl group. It is a copolymer with a (meth) acrylate monomer having a linear or branched alkyl group having 1 to 8 carbon atoms. Since such a copolymer is excellent in reactivity with a crosslinking agent containing peroxide as a main component, an adhesive having excellent adhesive properties can be obtained.

Carbon number of the alkyl group of the (meth) acrylate monomer having a linear or branched alkyl group (unit having an alkyl group not substituted with a hydroxyl group); C ₁ is preferably 2 to 8, and Preferably it is 2-6, Most preferably, it is 4-6. Carbon number of the alkyl group of the (meth) acrylate monomer (unit having an alkyl group substituted with a hydroxyl group) having a linear or branched alkyl group in which at least one hydrogen atom is substituted with a hydroxyl group; C ₂ is preferably equal to or above C _1, or more than the C _1, more preferably from 2 to 8, particularly preferably 4 to 6. Thus, by adjusting the carbon number of the alkyl group, the reactivity with the crosslinking agent can be improved, and a pressure-sensitive adhesive having even more excellent pressure-sensitive adhesive properties can be obtained.

Particularly preferably, the (meth) acrylate-based (co) polymer is a (meth) acrylate-based monomer having a linear or branched alkyl group having 1 to 8 carbon atoms, and at least one hydrogen atom is substituted with a hydroxyl group. A copolymer with a (meth) acrylate monomer having a linear or branched alkyl group having 1 to 8 carbon atoms, wherein the linear or branched chain having 1 to 8 carbon atoms in which at least one hydrogen atom is substituted with a hydroxyl group A unit derived from a (meth) acrylate monomer having a branched alkyl group is contained in an amount of 0.1 mol% to 10.0 mol%. The unit derived from a (meth) acrylate monomer having a linear or branched alkyl group having 1 to 8 carbon atoms in which at least one hydrogen atom is substituted with a hydroxyl group, more preferably 0.2 mol% to 5.0 mol. %, Particularly preferably from 0.3 mol% to 1.1 mol%.

Examples of the (meth) acrylate monomer having a linear or branched alkyl group having 1 to 8 carbon atoms in which at least one hydrogen atom is substituted with a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meta ) Acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, 3- Examples include hydroxy-3-methylbutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 7-hydroxyheptyl (meth) acrylate, and 8-hydroxyoctyl (meth) acrylate.

Any suitable crosslinking agent may be employed as long as it contains a peroxide as a main component. The peroxide is used for generating radicals by thermal decomposition and crosslinking the (meth) acrylate-based (co) polymer. Examples of the peroxide include hydroperoxides, dialkyl peroxides, peroxyesters, diacyl peroxides, peroxydicarbonates, peroxyketals, and ketone peroxides. Specific examples of the peroxide include di (2-ethylhexyl) peroxydicarbonate, di (4-t-butylcyclohexyl) peroxydicarbonate, t-butylperoxyneodecanoate, and t-hexylperoxy. Pivalate, t-butylperoxypivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, di (4- Methylbenzoyl) peroxide, dibenzoyl peroxide, t-butyl peroxybutyrate, benzoyl-m-methylbenzoyl peroxide, m-toluoyl peroxide and the like. These peroxides can be used alone or in combination of two or more.

The cross-linking agent preferably contains a diacyl peroxide peroxide, more preferably dibenzoyl peroxide and / or benzoyl m-methylbenzoyl peroxide. Such a peroxide, for example, has a half-life of 90 ° C. to 140 ° C. for 1 minute, so that it has excellent storage stability and can control the crosslinking reaction with high accuracy.

A commercially available crosslinking agent can be used as it is. Or a solvent and an additive can also be mixed and used for a commercially available thing. Examples of commercially available cross-linking agents based on peroxides include, for example, Parroyl series (trade name “IB, 335, L, SA, IPP, NPP, TCP, etc.” manufactured by Nippon Oil & Fats Co., Ltd. Product names such as “FF, BO, NS, E, BMT-Y, BMT-K40, BMT-M,” and the like.

An appropriate amount of the crosslinking agent can be appropriately selected according to the purpose. The amount (weight ratio) of the cross-linking agent is preferably 0.01 to 1.0, more preferably 0.05 to 0.8, relative to the (meth) acrylate (co) polymer 100. Especially preferably, it is 0.1-0.5, Most preferably, it is 0.15-0.45. By setting the blending amount of the crosslinking agent in the above range, it is possible to obtain a pressure-sensitive adhesive layer having excellent adhesive properties and a low moisture content, and as a result, a laminate having excellent adhesion and light release properties. A film can be obtained.

In one embodiment, the composition further contains a compound having an isocyanate group and / or a silane coupling agent. The compound having an isocyanate group is used to improve the adhesion strength (also referred to as anchoring force) at the interface between the first pressure-sensitive adhesive layer and the retardation film. The silane coupling agent is used to improve the adhesion with the substrate of the liquid crystal cell.

As the compound having an isocyanate group, an appropriate one can be appropriately selected. Examples of the compound having an isocyanate group include triresin isocyanate, chlorophenylene diisocyanate, hexamethylene isocyanate, tetramethylene isocyanate, isophorone diisocyanate, xylylene diisocyanate, diphenylmethane isocyanate, trimethylolpropane xylene diisocyanate, and the like. Or the adduct type isocyanate compound using the compound which has these isocyanate groups, an isocyanurate, a biuret type compound, etc. are mentioned. These compounds having an isocyanate group can be used alone or in combination of two or more. Preferably, the compound having an isocyanate group used in the first pressure-sensitive adhesive layer is trimethylolpropane xylene diisocyanate.

A commercially available compound can be used as it is as the compound having an isocyanate group. Or a solvent and an additive can also be mixed and used for a commercially available thing. Examples of commercially available compounds having an isocyanate group include Takenate series (trade name “500, 600, 700, etc.”) manufactured by Mitsui Takeda Chemical Co., Ltd., Coronate series (trade name “L, MR, EH, HL, etc. ".

The compounding amount of the compound having an isocyanate group can be appropriately selected depending on the purpose. The compounding amount (weight ratio) of the compound having an isocyanate group is preferably 0.005 to 1.0, more preferably 0.008 to 0.00 with respect to the (meth) acrylate-based (co) polymer 100. 8, particularly preferably 0.01 to 0.5, and most preferably 0.015 to 0.2. By setting the blending amount of the compound having an isocyanate group within the above range, a laminated film in which the interface between the first pressure-sensitive adhesive layer and the retardation film is difficult to peel off even under more severe high temperature and humidity environment is obtained. be able to.

As the silane coupling agent, one having an appropriate functional group can be appropriately selected. Examples of the functional group include a vinyl group, an epoxy group, a methacryloxy group, an amino group, a mercapto group, an acryloxy group, an acetoacetyl group, an isocyanate group, a styryl group, and a polysulfide group. Specific examples of the silane coupling agent include vinyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, and γ-methacryloxypropyltrimethoxy. Silane, γ-acryloxypropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropyltrimethoxysilane, γ-aminopropylmethoxysilane, γ-mercaptopropylmethyldimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide , Γ-isocyanatopropyltrimethoxysilane and the like. Preferably, the silane coupling agent used for the first pressure-sensitive adhesive layer is a silane coupling agent having an acetoacetyl group.

A commercially available silane coupling agent can be used as it is. Or a solvent and an additive can also be added and used for a commercially available thing. Examples of commercially available silane coupling agents include the KA series (trade name “KA-1003”, etc.) manufactured by Shin-Etsu Silicone Co., Ltd., and the KBM series (trade names “KBM-303, KBM-403, KBM-503”, etc.) manufactured by the same company. ”, The company's KBE series (trade names“ KBE-402, KBE-502, KBE-903, etc. ”), the Toray Industries, Inc. SH series (trade names“ SH6020, SH6040, SH6062 etc. ”), the company ’s SZ series (products) The names “SZ6030, SZ6032, SZ6300, etc.” are mentioned.

An appropriate amount of the silane coupling agent can be appropriately selected depending on the purpose. The blending amount (weight ratio) is preferably 0.001 to 2.0, more preferably 0.005 to 2.0, and particularly preferably with respect to the (meth) acrylate-based (co) polymer 100. Is 0.01 to 1.0, most preferably 0.02 to 0.5. By making the compounding quantity of the said silane coupling agent into said range, the laminated | multilayer film in which peeling and a bubble do not generate | occur | produce even in the severer high temperature and humid environment can be obtained.

In one embodiment, the composition is prepared by a method comprising the following steps 1-A and 1-B.
Step 1-A: A step of preparing a polymer solution (1-A) by diluting a (meth) acrylate-based (co) polymer with a solvent,
Step 1-B: A polymer solution (1-A) obtained in Step 1-A is blended with a crosslinking agent mainly composed of a peroxide, a compound having an isocyanate group, and a silane coupling agent. A step of adjusting 1-B).

Steps 1-A and 1-B are performed in order to obtain a uniform composition by uniformly dispersing or dissolving the blended substances. When the (meth) acrylate-based (co) polymer is polymerized by a solution polymerization method, the obtained reaction solution may be used as it is as the polymer solution (1-A). Alternatively, the resulting reaction solution may be further diluted by adding a solvent.

As the solvent, a solvent obtained by uniformly diluting the (meth) acrylate-based (co) polymer is preferably used. Examples of the solvent include toluene, xylene, chloroform, dichloromethane, dichloroethane, phenol, diethyl ether, tetrahydrofuran, anisole, tetrahydrofuran, acetone, methyl isobutyl ketone, methyl ethyl ketone, cyclohexanone, cyclopentanone, 2-hexanone, 2-pyrrolidone, N-methyl-2-pyrrolidone, n-butanol, 2-butanol, cyclohexanol, isopropyl alcohol, t-butyl alcohol, glycerin, ethylene glycol, diethylene glycol dimethyl ether, 2-methyl-2,4-pentanediol dimethylformamide, dimethylacetamide , Acetonitrile, butyronitrile, methyl cellosolve, methyl cellosolve acetate, ethyl acetate, butyl acetate And the like. The solvent is preferably toluene or ethyl acetate. These solvents are excellent in productivity, workability, and economy.

The total solid content concentration of the polymer solution (1-B) is preferably 1% by weight to 40% by weight, and more preferably 5% by weight to 30% by weight. By setting the total solid content concentration within the above range, a material having excellent coating property to a substrate can be obtained, and as a result, a pressure-sensitive adhesive layer having excellent surface uniformity can be obtained.

In addition to this, any appropriate additive may be added to the composition. Examples of the additive include a plasticizer, a heat stabilizer, a light stabilizer, a lubricant, an antioxidant, an ultraviolet absorber, a flame retardant, a colorant, an antistatic agent, a compatibilizer, a crosslinking agent, and a thickener. Etc. The blending amount (weight ratio) of the additive can be appropriately set according to the purpose. Preferably, the compounding amount (weight ratio) of the additive is more than 0 and 5 or less with respect to the (meth) acrylate (co) polymer 100.

As a method of blending each material when preparing the composition, an appropriate method can be adopted as appropriate. Preferably, the composition is prepared by adding a crosslinking agent mainly composed of a peroxide, a compound having an isocyanate group, and a silane coupling agent in this order to a (meth) acrylate-based (co) polymer. In the case where either or both of the compound having an isocyanate group and the silane coupling agent are not blended, the blending step is omitted.

D-4. Method of crosslinking composition (first pressure-sensitive adhesive layer)
As a method for crosslinking the composition, an appropriate method can be appropriately employed depending on the purpose. Preferably, the method of heating the said composition at 50 to 200 degreeC is used. The heating temperature is preferably 70 ° C to 190 ° C, more preferably 100 ° C to 180 ° C, and particularly preferably 120 ° C to 170 ° C. By setting the heating temperature within the above range, a side-reaction is not caused and a crosslinking reaction between the peroxide and the polymer occurs rapidly, and a pressure-sensitive adhesive having excellent pressure-sensitive adhesive properties can be obtained.

In the case where a heating method is employed to crosslink the composition, an appropriate time can be appropriately employed as the heating time. The heating time is preferably 5 seconds to 20 minutes, more preferably 5 seconds to 10 minutes, and particularly preferably 10 seconds to 5 minutes. By setting the heating time within the above range, the crosslinking reaction between the peroxide and the polymer is efficiently performed.

In one embodiment, the composition is cross-linked by the method including the following step 1-C and step 1-D after the step 1-A and step 1-B.
Step 1-C: a step of coating the base material with the polymer solution (1-B) obtained in Step 1-B,
Step 1-D: A step of drying the coated product obtained in Step 1-C at 50 ° C. to 200 ° C. to form an adhesive layer on the surface of the substrate.

Step 1-C is performed in order to thinly develop the polymer solution on the base material and obtain a thin film-like coated product. Step 1-D is performed to evaporate the solvent of the coated material and to crosslink the peroxide and the polymer. In addition, you may perform said drying in multiple steps, for example using the several temperature control means to which different temperature was set. According to such a method, a pressure-sensitive adhesive layer having a small thickness variation can be efficiently obtained, and a cross-linking reaction between a peroxide and a polymer can be appropriately performed to obtain a pressure-sensitive adhesive layer having excellent adhesive properties. it can.

As a method of applying the polymer solution (1-B) to the substrate, a coating method using an appropriate coater is appropriately employed. Examples of the coater include a reverse roll coater, a forward rotation roll coater, a gravure coater, a knife coater, a rod coater, a slot orifice coater, a curtain coater, a fountain coater, an air doctor coater, a kiss coater, a dip coater, a bead coater, a blade coater, and a cast coater. , Spray coater, spin coater, extrusion coater, hot melt coater and the like. A reverse roll coater, a gravure coater, a slot orifice coater, a curtain coater, and a fountain coater are preferable. If it is a coating method using said coater, the coated material which is excellent in surface uniformity can be obtained.

As the base material, an appropriate one can be appropriately selected according to the purpose. Preferably, the base material used is a surface on which the polymer solution (1-B) is applied and subjected to a release treatment. A polymer film is preferably used as the substrate. This is because roll production is possible and productivity can be greatly improved. The substrate may be a retardation film used in the present invention, or other polymer film. Preferably, the base material is a polyethylene terephthalate film treated with a silicone-based release agent. According to such a form, the said film can be used as a peeling liner of a laminated | multilayer film. The release liner is usually peeled before the laminated film is put into practical use.

As the temperature control means for heating or drying the composition, an appropriate one can be appropriately selected. Examples of the temperature control means include an air circulation type constant temperature oven in which hot air or cold air circulates, a heater using microwaves or far infrared rays, a roll heated for temperature adjustment, a heat pipe roll, a metal belt, or the like. It is done.

In one embodiment, the pressure-sensitive adhesive layer is laminated by a method including the following step 1-E after the step 1-A to step 1-D.
Step 1-E: a step of transferring the pressure-sensitive adhesive layer formed on the surface of the substrate obtained in Step 1-D to a retardation film to obtain a laminate.

According to such a method, the optical characteristics of the retardation film hardly change, and a laminated film having excellent optical characteristics can be obtained. The pressure-sensitive adhesive layer may be transferred to the retardation film after being peeled off from the substrate, transferred to the retardation film while being peeled off from the substrate, or transferred to the retardation film. You may peel from a base material. By doing so, a laminate having excellent surface uniformity can be obtained.

When the 1st adhesive layer used for this invention contains the adhesive which can be obtained by bridge | crosslinking the composition containing the compound which has an isocyanate group, Preferably, the said 1st adhesive layer is process 1-. After E, aging is performed by a method further including Step 1-F.
Step 1-F: A step of storing the laminate obtained in Step 1-E for at least 3 days.

Step 1-F is performed to age the pressure-sensitive adhesive layer. In this specification, “aging (also referred to as aging)” means that the pressure-sensitive adhesive layer is allowed to stand (store) for a certain period of time under appropriate conditions, thereby allowing diffusion of a substance contained in the pressure-sensitive adhesive layer and a chemical reaction. To obtain favorable properties and conditions.

As the temperature for aging the pressure-sensitive adhesive layer (aging temperature), an appropriate temperature can be appropriately selected depending on the kind of the polymer and the crosslinking agent, the aging time, and the like. The aging temperature is preferably 10 ° C to 80 ° C, more preferably 20 ° C to 60 ° C, and particularly preferably 20 ° C to 40 ° C. By selecting the above temperature range, a pressure-sensitive adhesive layer having stable pressure-sensitive adhesive properties can be obtained.

As the time for aging the pressure-sensitive adhesive layer (aging time), an appropriate time can be appropriately selected depending on the kind of the polymer and the crosslinking agent, the aging temperature, and the like. The aging temperature is preferably 3 days or more, more preferably 5 days or more, and particularly preferably 7 days or more. By selecting the above time, an adhesive layer having stable adhesive properties can be obtained.

An example of the manufacturing method of a 1st adhesive layer is demonstrated with reference to FIG. FIG. 4 is a schematic view showing the concept of a typical production process for the first pressure-sensitive adhesive layer used in the present invention. For example,
As a base material, a polyethylene terephthalate film 502 treated with a silicone-based release agent is fed from the first feeding unit 501 and obtained by diluting a (meth) acrylate-based (co) polymer with a solvent in the coater unit 503. The polymer solution (1-B) prepared by blending the polymer solution (1-A) with a crosslinking agent mainly composed of a peroxide, a compound having an isocyanate group, and a silane coupling agent is applied. The The coated material coated on the surface of the substrate is sent to a temperature control means (drying means) 504, and dried and crosslinked at, for example, 50 ° C. to 200 ° C. to form an adhesive layer. The retardation film 506 is fed out from the second feeding unit 506 and transferred to the pressure-sensitive adhesive layer by the laminate rolls 507 and 508. The laminate 509 of the thus obtained retardation film, the first pressure-sensitive adhesive layer, and the polyethylene terephthalate film 502 treated with the silicone release agent is wound up by the winding unit 510. The polyethylene terephthalate film 502 treated with a silicone release agent can be used as it is as a release liner.

D-5. Physical and chemical properties of the first pressure-sensitive adhesive layer The pressure-sensitive adhesive (as a result of the first pressure-sensitive adhesive layer) obtainable by the above method is preferably characterized by the following physical and chemical properties: .

The gel fraction of the pressure-sensitive adhesive is preferably 40% to 90%, more preferably 50% to 90%, and particularly preferably 60% to 85%. By setting the gel fraction within the above range, an adhesive layer having good adhesive properties can be obtained. In general, when a part (also referred to as a gel part) in which a polymer of an adhesive is crosslinked to form a three-dimensional network structure is immersed in a solvent, the volume is increased by absorbing the solvent. This phenomenon is called swelling. The said gel fraction is the value measured by the method as described in an Example.

The glass transition temperature (Tg) of the pressure-sensitive adhesive is preferably −70 ° C. to −10 ° C., more preferably −60 ° C. to −20 ° C., and particularly preferably −50 ° C. to −30 ° C. By setting the glass transition temperature in the above range, the retardation film has strong adhesiveness, and has an appropriate adhesiveness to the substrate (glass plate) of the liquid crystal cell, A pressure-sensitive adhesive layer excellent in light peelability can be obtained.

The moisture content of the pressure-sensitive adhesive is preferably 1.0% or less, more preferably 0.8% or less, and particularly preferably 0.6% or less. Most preferably, it is 0.4% or less. The theoretical lower limit of moisture content is zero. By setting the moisture content within the above range, it is possible to obtain a pressure-sensitive adhesive layer in which foaming hardly occurs even in a high temperature environment. In addition, the said moisture content is the value calculated | required from the weight decreasing rate after throwing an adhesive layer into a 150 degreeC air circulation type thermostat oven, and 1 hour progress.

E. Second pressure-sensitive adhesive layer In the laminated film of the present invention, preferably, a second pressure-sensitive adhesive layer may be further disposed between the polarizing plate and the retardation film. FIG. 5 is a schematic cross-sectional view of a laminated film according to one embodiment of the present invention. Note that the ratio of the vertical, horizontal, and thickness of each component in FIG. 5 is different from the actual ratio. The laminated film 11 includes at least a polarizing plate 20, a second pressure-sensitive adhesive layer 42, a retardation film 30, and a first pressure-sensitive adhesive layer 41 in this order. The polarizing plate 20 includes a polarizer 21, a first protective layer 22 disposed on the side of the polarizer 21 including the retardation film 30, and a side opposite to the side of the polarizer 21 including the retardation film 30. And a second protective layer 23 disposed on the surface. The retardation film 30 is a stretched film containing a norbornene resin. The 1st adhesive layer 41 contains the adhesive which can be obtained by bridge | crosslinking the composition which mix | blended at least the (meth) acrylate type | system | group (co) polymer and the crosslinking agent which has a peroxide as a main component. The 2nd adhesive layer 42 is obtained by bridge | crosslinking the composition which mix | blended at least the (meth) acrylate type | system | group (co) polymer, the crosslinking agent which has a compound which has an isocyanate group as a main component, and a silane coupling agent. A pressure sensitive adhesive.

E-1. Various physical properties of the second pressure-sensitive adhesive layer The thickness of the second pressure-sensitive adhesive layer can be appropriately selected depending on the purpose. The thickness of the second pressure-sensitive adhesive layer is preferably 2 μm to 50 μm, more preferably 2 μm to 40 μm, and particularly preferably 5 μm to 35 μm. By setting the thickness of the second pressure-sensitive adhesive layer in the above range, a pressure-sensitive adhesive layer having excellent pressure-sensitive adhesive properties can be obtained.

The transmittance of the second pressure-sensitive adhesive layer measured with light having a wavelength of 590 nm at 23 ° C. is preferably 90% or more. The theoretical upper limit of the transmittance is 100%, and the realizable upper limit is 96%.

Re [590] of the second pressure-sensitive adhesive layer is preferably less than 2 nm, and more preferably less than 1 nm. Rth [590] of the second pressure-sensitive adhesive layer is preferably less than 2 nm, more preferably less than 1 nm.

The adhesive force (F _2A ) to the retardation film at 23 ° C. of the second pressure-sensitive adhesive layer is preferably 6 N / 25 mm to 40 N / 25 mm, more preferably 8 N / 25 mm to 40 N / 25 mm, and particularly preferably. Is 10 N / 25 mm to 35 N / 25 mm.

The adhesive strength is as follows: a polarizing plate with an adhesive layer having a width of 25 mm is applied to a glass plate with a 2 kg roller, and after curing for 1 hour at 23 ° C., the polarizing plate with an adhesive layer is 300 mm / min in a 90-degree direction. It is the adhesive strength at the time of peeling.

The anchoring force (F _2B ) on the polarizing plate (first protective layer) at 23 ° C. of the second pressure-sensitive adhesive layer is preferably 10 N / 25 mm to 40 N / 25 mm, more preferably 13 N / 25 mm to 40 N / 25 mm, particularly preferably 16 N / 25 mm to 35 N / 25 mm. The anchoring force is obtained by pressing a laminate of a 25 mm wide adhesive layer and a polarizing plate on a treated surface of a polyethylene terephthalate film vapor-deposited with indium tin oxide with a 2 kg roller, and cultivating at 23 ° C. for 1 hour. Then, it is the adhesive strength at the time of peeling such a polyethylene terephthalate film at 300 mm / min.

In the laminated film of the present invention, the adhesive force (F _1A ) of the first pressure-sensitive adhesive layer to the 23 ° C. glass plate and the anchoring force (F _1B ) of the first pressure-sensitive adhesive layer to the retardation film at 23 ° C. ), The adhesive force of the second pressure-sensitive adhesive layer to the retardation film at 23 ° C. (F _2A ), and the anchoring force of the second pressure-sensitive adhesive layer to the polarizing plate (first protective layer) at 23 ° C. F _2B ) is set so that F _1A becomes the smallest, for example, F _1A <F _2A ≦ F _2B ≦ F _1B .

In one embodiment, the adhesive force (F _1A ) of the first pressure-sensitive adhesive layer to a 23 ° C. glass plate, and the adhesive force (F _2A ) of the second pressure-sensitive adhesive layer to a retardation film at 23 ° C. The difference (F _2A -F _1A ) is preferably 3 N / 25 mm or more, more preferably 3 N / 25 mm to 37 N / 25 mm, particularly preferably 4 N / 25 mm to 37 N / 25 mm, and most preferably 5 N. / 25 mm to 31 N / 25 mm. By setting the relationship between F _2A and F _{1A in} the above range, a laminated film excellent in light peelability can be obtained without any pressure-sensitive adhesive layer or retardation film remaining on the surface of the liquid crystal cell.

In another embodiment, the adhesive force (F _1A ) of the first pressure-sensitive adhesive layer to the 23 ° C. glass plate and the anchoring of the second pressure-sensitive adhesive layer to the polarizing plate (first protective layer) at 23 ° C. The difference (F _2B −F _1A ) from the force (F _2B ) is preferably 5 N / 25 mm or more, more preferably 5 N / 25 mm to 40 N / 25 mm, and particularly preferably 6 N / 25 mm to 37 N / 25 mm. And most preferably 6 N / 25 mm to 31 N / 25 mm. By setting the relationship between F _2B and F _{1A in} the above range, a pressure-sensitive adhesive layer and a retardation film do not remain on the surface of the liquid crystal cell, and a laminated film excellent in light peelability can be obtained.

The second pressure-sensitive adhesive layer may further contain any appropriate additive. Examples of the additive include metal powder, glass fiber, glass beads, silica, and a filler. Moreover, the said 2nd adhesive layer may contain the transfer substance (for example, residual solvent, additive, oligomer, etc.) from an adjacent layer. The content (weight ratio) of the additive is preferably more than 0 and 10 or less with respect to 100 of the total solid content of the second pressure-sensitive adhesive layer. Further, the content (weight ratio) of the transition material is preferably more than 0 and 5 or less with respect to the total solid content 100 of the second pressure-sensitive adhesive layer.

E-2. The pressure-sensitive adhesive forming the second pressure-sensitive adhesive layer The pressure-sensitive adhesive forming the second pressure-sensitive adhesive layer is composed of a (meth) acrylate-based (co) polymer, a crosslinking agent mainly composed of a compound having an isocyanate group, and silane. It can be obtained by crosslinking a composition containing at least a coupling agent.

E-3. Preparation of raw material composition (second adhesive layer)
As the (meth) acrylate-based (co) polymer, an appropriate one can be appropriately employed depending on the purpose. The said (meth) acrylate type | system | group (co) polymer says the (co) polymer obtained using a (meth) acrylate type monomer. When the polymer is a copolymer, the arrangement state of the molecules is not particularly limited, and may be a random copolymer, a block copolymer, or a graft copolymer. May be. The molecular arrangement state of the (meth) acrylate-based (co) polymer is preferably a random copolymer. The (meth) acrylate-based (co) polymer can be obtained, for example, by the method described in the section D-3.

The weight average molecular weight (Mw) of the (meth) acrylate-based (co) polymer can be appropriately set to an appropriate value. Preferably, the weight average molecular weight (Mw) is a value measured by a gel permeation chromatograph (GPC) method using a tetrahydrofuran solvent, preferably 1,000,000 or more, more preferably 1,200, 000 to 3,000,000, particularly preferably 1,200,000 to 2,000,000. The said weight average molecular weight (Mw) can be suitably adjusted suitably with the kind of solvent, superposition | polymerization temperature, an additive, etc.

Examples of the (meth) acrylate-based (co) polymer include those described in the section D-3. Preferably, the (meth) acrylate-based (co) polymer is a (meth) acrylate-based monomer having a linear or branched alkyl group having 1 to 8 carbon atoms, a (meth) acrylate-based monomer, and at least one hydrogen. It is a copolymer with a (meth) acrylate monomer having a linear or branched alkyl group having 1 to 8 carbon atoms in which an atom is substituted with a hydroxyl group. By using such a copolymer, an adhesive having excellent adhesive properties can be obtained.

Carbon number of the alkyl group of the (meth) acrylate monomer having a linear or branched alkyl group (unit not substituted with a hydroxyl group); C ₁ is preferably 2 to 8, and more preferably 2 to 2. 6, particularly preferably 4-6. The carbon number of the alkyl group of the (meth) acrylate monomer (unit substituted with a hydroxyl group) having a linear or branched alkyl group in which at least one hydrogen atom is substituted with a hydroxyl group; C ₂ is preferably It is less than C ₁ , more preferably 2 to 4, and particularly preferably 2. Thus, by adjusting the carbon number of the alkyl group, the reactivity with the crosslinking agent can be improved, and a pressure-sensitive adhesive having even more excellent pressure-sensitive adhesive properties can be obtained.

Particularly preferably, the (meth) acrylate-based (co) polymer is a (meth) acrylate-based monomer having a linear or branched alkyl group having 1 to 8 carbon atoms, a (meth) acrylate-based monomer, and at least one It is a copolymer with a (meth) acrylate monomer having a linear or branched alkyl group having 1 to 8 carbon atoms in which a hydrogen atom is substituted with a hydroxyl group, and the number of carbon atoms in which at least one hydrogen atom is substituted with a hydroxyl group A unit derived from a (meth) acrylate monomer having 1 to 8 linear or branched alkyl groups is contained in an amount of 0.05 mol% to 0.25 mol%. The unit derived from a (meth) acrylate monomer having a linear or branched alkyl group having 1 to 8 carbon atoms in which at least one hydrogen atom is substituted with a hydroxyl group is more preferably 0.10 mol% to 0.22 mol. %, Particularly preferably 0.14 mol% to 0.20 mol%.

Examples of the (meth) acrylate monomer having a linear or branched alkyl group having 1 to 8 carbon atoms in which at least one hydrogen atom is substituted with a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meta ) Acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, 3- Examples include hydroxy-3-methylbutyl (meth) acrylate, 6-hydroxyhexyl (meth) acrylate, 7-hydroxyheptyl (meth) acrylate, and 8-hydroxyoctyl (meth) acrylate.

Any suitable crosslinking agent may be employed as long as it contains a compound having an isocyanate group as a main component. Examples of the compound having an isocyanate group include those described in the section D-3.

An appropriate amount of the crosslinking agent can be selected as appropriate. The blending amount (weight ratio) of the cross-linking agent is preferably 0.15 to 1.0, more preferably 0.30 to 0.90 with respect to the (meth) acrylate-based (co) polymer 100. Particularly preferably, it is 0.39 to 0.81, and most preferably 0.48 to 0.72. By setting the blending amount of the cross-linking agent in the above range, a laminated film in which the interface between the second pressure-sensitive adhesive layer and the retardation film is difficult to peel off even under more severe high temperature and high humidity environment can be obtained. .

Examples of the silane coupling agent include those described in the section D-3. The silane coupling agent used in the second pressure-sensitive adhesive layer is preferably a silane coupling agent having an epoxy group, and more preferably γ-gridoxypropyltrimethoxysilane.

An appropriate amount of the silane coupling agent can be appropriately selected depending on the purpose. The blending amount (weight ratio) is preferably 0.01 to 0.20, more preferably 0.037 to 0.113, particularly preferably with respect to the (meth) acrylate-based (co) polymer 100. Is 0.049 to 0.101, most preferably 0.060 to 0.090. By making the compounding quantity of the said silane coupling agent into said range, the laminated | multilayer film in which peeling and a bubble do not generate | occur | produce even in the severer high temperature and humid environment can be obtained.

In one embodiment, the composition is prepared by a method comprising the following steps 2-A and 2-B.
Step 2-A: A step of preparing a polymer solution (2-A) by diluting a (meth) acrylate-based (co) polymer with a solvent,
Step 2-B: A polymer solution (2-B) obtained by blending a polymer solution (2-A) obtained in Step 2-A with a crosslinking agent containing a compound having an isocyanate group as a main component and a silane coupling agent. Adjusting the process.

Steps 2-A and 2-B are performed to uniformly disperse or dissolve the blended substance to obtain a uniform composition. When the (meth) acrylate-based (co) polymer is polymerized by a solution polymerization method, the obtained reaction solution may be used as it is as the polymer solution (2-A). Alternatively, the resulting reaction solution may be further diluted by adding a solvent.

Examples of the solvent include those described in the section D-3. Preferably, the solvent is toluene or ethyl acetate. These solvents are excellent in productivity, workability, and economy.

The total solid content concentration of the polymer solution (2-B) is preferably 5% by weight to 50% by weight, and more preferably 10% by weight to 40% by weight. By setting the total solid content concentration within the above range, a material having excellent coating property to a substrate can be obtained, and as a result, a pressure-sensitive adhesive layer having excellent surface uniformity can be obtained.

In addition to this, any appropriate additive may be added to the composition. Examples of the additive include those described in the section D-3. The amount (weight ratio) of the additive is preferably more than 0 and 5 or less with respect to the (meth) acrylate-based (co) polymer 100.

As a method of blending each material when preparing the composition, an appropriate method can be adopted as appropriate. Preferably, the composition is prepared by adding a silane coupling agent to a (meth) acrylate-based (co) polymer after adding a cross-linking agent containing a compound having an isocyanate group as a main component.

E-4. Method for crosslinking composition (second pressure-sensitive adhesive layer)
As a method for crosslinking the composition, an appropriate method can be appropriately employed depending on the purpose. Preferably, the method of heating the said composition at 20 to 200 degreeC is used. The heating temperature is preferably 50 ° C to 170 ° C. By setting the heating temperature within the above range, an adhesive layer having excellent surface uniformity can be obtained.

As the heating time, an appropriate time can be appropriately adopted. The heating time is preferably 10 seconds to 20 minutes, more preferably 20 seconds to 10 minutes, and particularly preferably 30 seconds to 5 minutes. By setting the heating time in the above range, a pressure-sensitive adhesive layer having excellent surface uniformity can be obtained.

In one embodiment, the composition is crosslinked by a method including the following Step 2-C and Step 2-D after Step 2-A and Step 2-B.
Step 2-C: a step of coating the substrate with the polymer solution (2-B) obtained in Step 2-B,
Step 2-D: A step of drying the coated product obtained in Step 2-C at 20 ° C. to 200 ° C. to form an adhesive layer on the surface of the substrate.

Step 2-C is performed in order to obtain a coated product with small thickness variation. Step 2-D is performed to evaporate the solvent of the coated material. In addition, you may perform said drying in multiple steps, for example using the several temperature control means to which different temperature was set. According to such a method, a pressure-sensitive adhesive layer having a small thickness variation can be obtained efficiently.

The method of coating the polymer solution (2-B) on the substrate, the type of the substrate, and the temperature control means are, for example, the coating method using the coater described in the section D-4, the substrate, and the temperature. Control means are employed.

In one embodiment, the pressure-sensitive adhesive layer is laminated and aged by a method including the following steps 2-E and 2-F after the steps 2-A to 2-D.
Step 2-E: a step of transferring the pressure-sensitive adhesive layer formed on the surface of the substrate obtained in Step 2-D to a retardation film to obtain a laminate,
Step 2-F: A step of storing the laminate obtained in Step 2-E for at least 3 days.

According to such a method, the optical characteristics of the retardation film hardly change, and a laminated film having excellent optical characteristics can be obtained. The pressure-sensitive adhesive layer may be transferred to the phase difference film after being peeled off from the base material, or may be transferred to the phase difference film while being peeled off from the base material. It may be peeled from the material. By doing so, a laminate having excellent surface uniformity can be obtained. Step 2-F is performed for aging the pressure-sensitive adhesive layer.

As the temperature for aging the pressure-sensitive adhesive layer (aging temperature), an appropriate temperature can be appropriately selected depending on the kind of the polymer and the crosslinking agent, the aging time, and the like. The aging temperature is preferably 10 ° C to 80 ° C, more preferably 20 ° C to 60 ° C, and particularly preferably 20 ° C to 40 ° C. By selecting the above temperature range, a pressure-sensitive adhesive layer having stable pressure-sensitive adhesive properties can be obtained.

As the time for aging the pressure-sensitive adhesive layer (aging time), an appropriate time can be appropriately selected depending on the kind of the polymer and the crosslinking agent, the aging temperature, and the like. The aging temperature is preferably 3 days or more, more preferably 5 days or more, and particularly preferably 7 days or more. By selecting the above time, an adhesive layer having stable adhesive properties can be obtained.

E-5. Physical and chemical properties of the second pressure-sensitive adhesive layer The pressure-sensitive adhesive (as a result of the second pressure-sensitive adhesive layer) obtainable by the above method is preferably characterized by the following physical and chemical properties: .

The gel fraction of the pressure-sensitive adhesive is preferably 60% to 96%, more preferably 70% to 94%, and particularly preferably 78% to 92%. By setting the gel fraction within the above range, the pressure-sensitive adhesive layer has strong adhesiveness for the retardation film and has excellent adhesive properties for the substrate (glass plate) of the liquid crystal cell. Can be obtained.

The glass transition temperature (Tg) of the pressure-sensitive adhesive is preferably −42 ° C. to −14 ° C., more preferably −37 ° C. to −18 ° C., and particularly preferably −34 ° C. to −21 ° C. By setting the glass transition temperature within the above range, an adhesive layer having good adhesive properties can be obtained.

The moisture content of the pressure-sensitive adhesive is preferably 0.4% or more, and more preferably 0.4% to 0.8%. The theoretical lower limit of moisture content is zero. By setting the moisture content within the above range, a pressure-sensitive adhesive layer excellent in adhesiveness with the retardation film can be obtained. In addition, the said moisture content is the value calculated | required from the weight decreasing rate after throwing an adhesive layer into a 150 degreeC air circulation type thermostat oven, and 1 hour progress.

F. Liquid Crystal Panel FIGS. 6A and 6B are schematic cross-sectional views of a liquid crystal panel according to a preferred embodiment of the present invention. It should be noted that for the sake of easy understanding, the ratios of the vertical, horizontal, and thickness of the constituent members shown in FIGS. 6A and 6B are different from actual ones.

Referring to FIG. 6A, the liquid crystal panel 100 includes the laminated film 10 of the present invention on one side of the liquid crystal cell 50. Preferably, a reflective film (not shown) or a second polarizing plate (not shown) may be disposed on the other side of the liquid crystal cell 50. When the second polarizing plate is disposed, the second polarizing plate is preferably disposed so that the absorption axis direction thereof is substantially perpendicular to the absorption axis direction of the polarizer 21. In this specification, “substantially orthogonal” means that the angle formed by the absorption axis direction of the polarizer 21 and the absorption axis direction of the second polarizing plate (polarizer) is 90 ° ± 2.0 °. In some cases, it is preferably 90 ° ± 1.0 °, and more preferably 90 ° ± 0.5 °. In the present invention, the polarizers disposed on both sides of the liquid crystal cell may be the same or different.

Referring to FIG. 6B, the liquid crystal panel 101 includes the laminated film 10 of the present invention on one side of the liquid crystal cell 50, and the laminated film 10 ′ of the present invention on the other side of the liquid crystal cell 50. Preferably, the laminated films 10 and 10 ′ are arranged so that the absorption axis direction of the polarizer 21 is substantially orthogonal to the absorption axis direction of the polarizer 21 ′. “Substantially orthogonal” includes the case where the angle formed by the absorption axis direction of the polarizer 21 and the absorption axis direction of the second polarizing plate (polarizer) is 90 ° ± 2.0 °, The angle is preferably 90 ° ± 1.0 °, and more preferably 90 ° ± 0.5 °. In the present invention, the laminated films 10 and 10 'may be the same or different.

Referring to FIG. 6, a liquid crystal cell 50 used in the present invention has a pair of substrates 51 and 51 'and a liquid crystal layer 52 as a display medium sandwiched between the substrates 51 and 51'. One substrate (active matrix substrate) 51 ′ includes 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 active element, and a signal line for supplying a source signal. Are provided (both not shown). The other substrate (color filter substrate) 51 is provided with a color filter. The color filter may be provided on the active matrix substrate 51 '. Alternatively, for example, when an RGB three-color light source is used for the illumination means of the liquid crystal display device as in the field sequential method, the color filter can be omitted. A distance (cell gap) between the substrate 51 and the substrate 51 ′ is controlled by a spacer (not shown). An alignment film (not shown) made of polyimide, for example, is provided on the side of the substrate 51 and the substrate 51 ′ in contact with the liquid crystal layer 52.

F. Liquid Crystal Display Device FIG. 7 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention. It should be noted that, for the sake of easy understanding, the ratio of the vertical, horizontal, and thickness of each component shown in FIG. 7 is different from the actual ratio. The liquid crystal display device 200 includes a liquid crystal panel 100 (or 101) and a backlight unit 80 disposed on one side of the liquid crystal panel 100. In the illustrated example, a case where a direct system is adopted as the backlight unit is shown, but this may be a side light system, for example. When the direct method is employed, the backlight unit 80 includes at least a backlight 81, a reflective film 82, a diffusion plate 83, a prism sheet 84, and a brightness enhancement film 85. When the sidelight system is adopted, the backlight unit further includes at least a light guide plate and a light reflector in addition to the above configuration. By using these optical members, the liquid crystal display device can obtain more excellent display characteristics. In addition, as long as the effect of the present invention is obtained, a part of the optical member illustrated in FIG. 7 can be omitted depending on the application, such as the illumination method of the liquid crystal display device and the driving mode of the liquid crystal cell, or Other optical members can be substituted.

The liquid crystal display device may be a transmissive type that irradiates light from the back side of the liquid crystal panel to view the screen, or a reflective type that irradiates light from the viewing side of the liquid crystal panel to view the screen. good. Alternatively, the liquid crystal display device may be a transflective type having both transmissive and reflective properties. Preferably, the liquid crystal display device of the present invention is a transmissive type. This is because a liquid crystal display device with small light leakage in an oblique direction can be obtained.

Any appropriate structure can be adopted as the backlight. As the structure of the backlight, typically, there are a “straight-line method” in which light is irradiated from directly below the liquid crystal panel and an “edge light method” in which light is irradiated from the lateral edge of the liquid crystal panel. Preferably, the structure of the illumination means is a direct type. This is because a direct-type backlight can obtain high luminance.

As the backlight, an appropriate one can be adopted as appropriate according to the purpose. Examples of the backlight include a cold cathode fluorescent tube (CCFL), a light emitting diode (LED), an organic EL (OLED), and a field emission device (FED). When a light emitting diode is employed for the backlight, the color of the light source may be white or RGB three colors. When an RGB three-color light source is used for the light emitting diode, a field sequential type liquid crystal display device capable of color display without using a color filter can be obtained.

The reflective film is used to prevent light from being lost to the side opposite to the viewing side of the liquid crystal panel and to make the light of the backlight enter the light guide plate efficiently. As the reflective film, for example, a polyethylene terephthalate film on which silver is vapor-deposited or a laminated film in which a polyester resin is laminated in multiple layers is used. The reflectance of the reflective film is preferably 90% or more over the entire wavelength range of 410 nm to 800 nm. The thickness of the reflective film is usually 50 μm to 200 μm. As the reflective film, a commercially available reflective film can be used as it is. Examples of the commercially available reflective film include Kimoto's Lef White series, Sumitomo 3M's Vicuity ESR series, and the like.

The light guide plate is used to spread light from the backlight over the entire screen. As the light guide plate, for example, an acrylic resin, a polycarbonate resin, a cycloolefin resin, or the like formed into a tapered shape so that the thickness decreases as the distance from the light source increases.

The diffusion plate is used to guide light emitted from the light guide plate to a wide angle and make the screen uniform brightness. As the diffusion plate, for example, a polymer film that has been subjected to uneven treatment or a polymer film containing a diffusion agent is used. The haze of the diffusion plate is preferably 85% to 92%. Furthermore, the total light transmittance of the diffusing plate is preferably 90% or more. As the diffusion plate, a commercially available diffusion plate can be used as it is. As a commercially available diffuser plate, for example, OPULS series manufactured by Eiwa Co., Ltd., light up series manufactured by Kimoto Co., Ltd., and the like can be given.

The prism sheet is used to collect light having a wide angle by the light guide plate in a specific direction and improve the luminance in the front direction of the liquid crystal display device. As the prism sheet, for example, a sheet in which a prism layer made of an acrylic resin or a photosensitive resin is laminated on the surface of a base film made of a polyester resin is used. As the prism sheet, a commercially available prism sheet can be used as it is. As a commercially available prism sheet, for example, Mitsubishi Rayon Co., Ltd. Diamond Art Series can be mentioned.

The said brightness improvement film is used in order to improve the brightness | luminance of the front of a liquid crystal display device, and a diagonal direction. A commercially available brightness enhancement film can be used as it is. Examples of commercially available brightness enhancement films include NIPOCS PCF series manufactured by Nitto Denko Corporation and Vicuity DBEF series manufactured by Sumitomo 3M Co., Ltd.

G. Display characteristics of liquid crystal display device The maximum value of the Y value in a polar angle of 60 ° and in all directions (0 ° to 360 °) when a black image of a liquid crystal display device provided with the laminated film of the present invention is displayed is preferably 0. 0.5 or less, more preferably 0.4 or less, and particularly preferably 0.3 or less. Further, the average value of Y values in a polar angle of 60 ° and in all directions (0 ° to 360 °) when displaying a black image of the liquid crystal display device is preferably 0.3 or less, and more preferably 0. .2 or less, particularly preferably 0.1 or less. The Y value is the tristimulus value Y defined by the CIE 1931XYZ display system, and the theoretical lower limit is zero. The smaller this value is, the smaller the amount of light leakage in the oblique direction of the screen of the liquid crystal display device displaying the black image.

In the liquid crystal display device of the present invention, the maximum value of the color shift amount (Δa ^* b ^* ) in a polar angle of 60 ° and in all directions (0 ° to 360 °) when displaying a black image is preferably 8.0. Or less, more preferably 6.0 or less, and particularly preferably 4.0 or less. Further, the average value of the color shift amount (Δa ^* b ^* ) in the polar angle 60 ° and in all directions (0 ° to 360 °) when displaying the black image of the liquid crystal display device is preferably 4.0 or less. More preferably, it is 3.0 or less, and particularly preferably 2.0 or less. Here, Δa ^* b ^* is a value calculated from the formula; {(a ^* ) ² + (b ^* ) ² } ^1/2 , and a ^* and b ^* are CIE1976L ^* a ^* b ^* color space. The theoretical lower limit of Δa ^* b ^* is 0. The smaller this value is, the smaller the color change in the oblique direction of the screen of the liquid crystal display device displaying the black image.

H. Application of the liquid crystal display device of the present invention The liquid crystal display device of the present invention is used for any appropriate application. Applications include, for example, OA equipment such as personal computer monitors, notebook computers, and copiers, mobile phones, watches, digital cameras, personal digital assistants (PDAs), portable devices such as portable game machines, video cameras, televisions, microwave ovens, etc. Home appliances, back monitors, car navigation system monitors, car audio and other in-vehicle equipment, exhibition equipment such as commercial store information monitors, security equipment such as surveillance monitors, nursing care monitors, medical monitors, etc. Nursing care / medical equipment.

Preferably, the use of the liquid crystal display device of the present invention is a television. In particular, it is preferably used for a large television. The screen size of the television is preferably a wide 17 type (373 mm × 224 mm) or more, more preferably a wide 23 type (499 mm × 300 mm) or more, and particularly preferably a wide 26 type (566 mm × 339 mm) or more. Most preferably, it is a wide 32 type (687 mm × 412 mm) or more.

The present invention will be further described using the above examples and comparative examples. In addition, this invention is not limited only to these Examples. In addition, each analysis method used in the Example is as follows.
(1) Measuring method of single transmittance, polarization degree, hue a value, hue b value of polarizing plate:
It measured at 23 degreeC using the spectrophotometer [Murakami Color Research Laboratory Co., Ltd. product name "DOT-3"].
(2) Measuring method of molecular weight:
Polystyrene was calculated as a standard sample by the gel permeation chromatograph (GPC) method. Specifically, it measured with the following apparatuses, instruments, and measurement conditions. The sample is
Measurement sample: The sample was dissolved in tetrahydrane to give a 0.1% by weight solution, allowed to stand overnight, and then filtered using a 0.45 μm membrane filter.
・ Analyzer: “HLC-8120GPC” manufactured by TOSOH
Column: TSKgelSuperHM-H / H4000 / H3000 / H2000
Column size: 6.0 mmI. D. × 150mm
-Eluent: Tetrahydrofuran-Flow rate: 0.6 ml / min.
・ Detector: RI
-Column temperature: 40 ° C
・ Injection volume: 20 μl
(3) Measuring method of thickness:
When the thickness was less than 10 μm, measurement was performed using a thin film spectrophotometer [manufactured by Otsuka Electronics Co., Ltd., “instant multiphotometry system MCPD-2000”]. When the thickness was 10 μm or more, measurement was performed using an Anritsu digital micrometer “KC-351C type”.
(4) Method for measuring the average refractive index of the film:
It calculated | required from the refractive index measured with the light of wavelength 589nm in 23 degreeC using the Abbe refractometer [The product name "DR-M4" by Atago Co., Ltd.].
(5) Measuring method of phase difference value (Re [480], Re [590], Rth [590]):
Using a trade name “KOBRA21-ADH” manufactured by Oji Scientific Instruments Co., Ltd., measurement was performed with light at wavelengths of 480 nm and 590 nm at 23 ° C.
(6) Measuring method of transmittance (T [590]):
It measured with the light of wavelength 590nm in 23 degreeC using the ultraviolet visible spectrophotometer [The product name "V-560" by JASCO Corporation].
(7) Measuring method of absolute value (C [590]) of photoelastic coefficient:
Using a spectroscopic ellipsometer [product name “M-220” manufactured by JASCO Corporation], the sample (size 2 cm × 10 cm) is sandwiched at both ends and stress (5 to 15 N) is applied to the phase difference at the center of the sample. The value (23 ° C./wavelength 590 nm) was measured and calculated from the slope of the function of stress and retardation value.
(8) Measuring method of shrinkage rate of shrinkable film:
It was determined according to the heat shrinkage ratio A method of JIS Z 1712-1997 (however, the heating temperature was changed to 140 ° C. (or 160 ° C.) instead of 120 ° C., and a load of 3 g was added to the test piece). Specifically, five test pieces each having a width of 20 mm and a length of 150 mm were taken from the vertical [MD] and horizontal [TD] directions, and a test piece with a mark at a distance of about 100 mm was prepared at the center of each. To do. The test piece was suspended vertically in an air circulation drying oven maintained at a temperature of 140 ° C. ± 3 ° C. (or 160 ° C. ± 3 ° C.) with a load of 3 g, heated for 15 minutes, taken out, and standard. After being left in the state (room temperature) for 30 minutes, the distance between the gauge points was measured using a caliper specified in JIS B 7507, and the average value of the five measured values was obtained, and S (%) = [[Heating Distance between previous gauge points (mm) −Distance between gauge points after heating (mm)] / Distance between gauge points before heating (mm)] × 100.
(9) Measuring method of shrinkage stress of shrinkable film:
Using the following apparatus, the shrinkage stress T ¹⁴⁰ [TD] and the shrinkage stress T ¹⁵⁰ [TD] in the width [TD] direction at 140 ° C. and 150 ° C. were measured by the TMA method.
Equipment: “TMA / SS6100” manufactured by Seiko Instruments Inc.
Data processing: “EXSTAR6000” manufactured by Seiko Instruments Inc.
・ Measurement mode: Constant temperature rise measurement (10 ℃ / min)
・ Measurement atmosphere: In air (23 ℃)
・ Load: 20mN
Sample size: 15mm x 2mm (long side is width [TD] direction)
(10) Measuring method of adhesive strength of pressure-sensitive adhesive layer:
A 25 mm wide sample was pressed against a glass plate once with a 2 kg roller, and after curing at 23 ° C. for 1 hour, the adhesive strength was measured when the sample was peeled off at 90 mm in a direction of 300 mm / min.
(11) Measuring method of anchoring force of adhesive layer:
A laminate of a 25 mm wide pressure-sensitive adhesive layer and a retardation film on a treated surface of a polyethylene terephthalate film [trade name “125 Tetraite OES” (thickness 125 μm) manufactured by Oike Kogyo Co., Ltd.] in which indium tin oxide is deposited. The film was subjected to one-way reciprocation with a 2 kg roller and cultivated at 23 ° C. for 1 hour, and then the adhesive strength was measured when the polyethylene terephthalate film was peeled off along the pressure-sensitive adhesive layer in the direction of 180 ° at 300 mm / min.
(12) Measuring method of glass transition temperature (Tg) of adhesive:
The differential scanning calorimeter manufactured by Seiko Denshi Kogyo Co., Ltd. was obtained by the DSC method according to JISK 7121 using the product name “DSC220C”.
(13) Measuring method of moisture content of adhesive:
The pressure-sensitive adhesive layer was put into a 150 ° C. air circulation type thermostatic oven, and the weight reduction rate after 1 hour [(W ₁ −W ₂ ) / W ₁ × 100] was obtained. Here, W ₁ is the weight of the pressure-sensitive adhesive layer before being charged into the air circulation type thermostatic oven, and W ₂ is the weight of the pressure-sensitive adhesive layer after being charged into the air circulation type constant temperature oven.
(14) Measuring method of gel fraction of adhesive:
A sample of the adhesive whose weight was measured in advance was placed in a container filled with ethyl acetate and allowed to stand at 23 ° C. for 7 days. Then, the adhesive was taken out, the solvent was wiped off, and the weight was measured. The gel fraction was determined from the following formula: [(W _A −W _B ) / W _A × 100]. Here, W _A is the weight of the adhesive layer before poured into ethyl acetate, W _B is the weight of the adhesive layer after poured into ethyl acetate.
(15) Measuring method of light leakage amount (Y) of liquid crystal display device:
After 30 minutes have passed since the light was turned on in a dark room at 23 ° C., an ELDIM product name “EZ Contrast 160D” was used to display a black image at an azimuth angle of 0 ° to 360 ° and a polar angle of 60 °. The tristimulus value Y value defined by the CIE1931XYZ display system was measured. The long side direction of the liquid crystal panel was set to an azimuth angle of 0 °, and the normal direction was set to a polar angle of 0 °.
(16) Measuring method of color shift amount (Δa ^* b ^* ) of liquid crystal display device:
After 30 minutes have passed since the light was turned on in a dark room at 23 ° C., an ELDIM product name “EZ Contrast 160D” was used to display a black image at an azimuth angle of 0 ° to 360 ° and a polar angle of 60 °. The color coordinates a ^* and b ^* defined in the CIE1976L ^* a ^* b ^* color space were measured. The color shift amount (Δa ^* b ^* ) in the oblique direction was calculated from the following equation: {(a ^* ) ² + (b ^* ) ² } ^1/2 .

<Production of retardation film>
[Reference Example 1]
Polymer film containing a resin (norbornene-based resin) obtained by hydrogenating a ring-opening polymer of norbornene-based monomer having a thickness of 100 μm [trade name “Zeonor ZF-14-100” manufactured by Optes Co., Ltd. (average refractive index = 1. 52, Tg = 136 ° C., Re [590] = 3.0 nm, Rth [590] = 5.0 nm)] on both sides of the shrinkable film A (biaxially stretched film containing polypropylene having a thickness of 60 μm [Toray Industries, Inc. ) Product name “Torphan BO2873”]) was bonded together via an acrylic adhesive layer (thickness 15 μm). Thereafter, the film longitudinal direction is maintained with a roll stretching machine and stretched 1.38 times in an air circulation oven at 146 ° C. After stretching, the shrinkable film A is peeled off together with the acrylic pressure-sensitive adhesive layer. A retardation film was prepared. The retardation film is referred to as retardation film A, and the characteristics are shown in Table 1. In this retardation film, the refractive index ellipsoid showed a relationship of nx>nz> ny, and the chromatic dispersion value (D) was 1.00. The physical properties of the shrinkable film A are shown in Table 2.

[Reference Examples 2-4, 6, 7]
Retardation films B to D, F, and G were produced in the same manner as in Reference Example 1 except that the stretching conditions shown in Table 2 were adopted. The properties of these retardation films are shown in Table 1. In these retardation films, the refractive index ellipsoid showed a relationship of nx>nz> ny, and the chromatic dispersion value (D) was 1.00.

[Reference Example 5]
A polymer film containing a resin (norbornene resin) obtained by hydrogenating a ring-opening polymer of a norbornene monomer having a thickness of 130 μm [trade name “ARTON FLZU130D0” (weight average molecular weight = 78,200, average refraction) Rate = 1.53, Tg = 135 ° C., Re [590] = 3.0 nm, Rth [590] = 5.0 nm)] on both sides of the shrinkable film A and an acrylic adhesive layer (thickness 15 μm). Pasted together. Thereafter, the film longitudinal direction is maintained with a roll stretching machine and stretched 1.38 times in an air circulation oven at 146 ° C. After stretching, the shrinkable film A is peeled off together with the acrylic pressure-sensitive adhesive layer. A retardation film E was produced. The characteristics are shown in Table 1. In this retardation film, the refractive index ellipsoid showed a relationship of nx>nz> ny, and the chromatic dispersion value (D) was 1.00.

[Reference Example 8]
A retardation film H was produced in the same manner as in Reference Example 5 except that the draw ratio was 1.43 and the shrinkable film B (biaxially stretched film containing polypropylene having a thickness of 60 μm) was used. The characteristics are shown in Table 1. In this retardation film, the refractive index ellipsoid showed a relationship of nx>nz> ny, and the chromatic dispersion value (D) was 1.00. Table 2 shows the physical properties of the shrinkable film B.

[Reference Example 9]
A retardation film I was produced in the same manner as in Reference Example 5 except that the draw ratio was 1.42 and the shrinkable film C (biaxially stretched film containing polypropylene having a thickness of 60 μm) was used. The characteristics are shown in Table 1. In this retardation film, the refractive index ellipsoid showed a relationship of nx>nz> ny, and the chromatic dispersion value (D) was 1.00. Table 2 shows the physical properties of the shrinkable film C.

[Reference Example 10] to [Reference Example 12]
A polymer film containing a resin (norbornene resin) obtained by hydrogenating a ring-opening polymer of a norbornene monomer having a thickness of 40 μm (trade name “Zeonor ZF-14-40” manufactured by Optes Co., Ltd.) (average refractive index = 1. 52, Tg = 136 ° C., Re [590] = 1.0 nm, Rth [590] = 3.0 nm)], and the stretching conditions were set as shown in Table 1, Example 1 Retardation films J to L were prepared in the same manner as described above. The properties of these retardation films are shown in Table 1. In these retardation films, the refractive index ellipsoid showed a relationship of nx>nz> ny, and the chromatic dispersion value (D) was 1.00.

[Reference Example 13]
Polymer film containing polycarbonate resin having a thickness of 55 μm [trade name “Elmec” manufactured by Kaneka Corporation (weight average molecular weight = 60,000, average refractive index = 1.53, Tg = 136 ° C., Re [590] = 1.0 nm, Rth [590] = 3.0 nm)] on both sides, a shrinkable film D (biaxially stretched film containing polypropylene having a thickness of 60 μm [trade name “Trefan BO2570A” manufactured by Toray Industries, Inc.]) It bonded together through the acrylic adhesive layer (thickness 15 micrometers). Thereafter, the film longitudinal direction is maintained with a roll stretching machine, and the film is stretched 1.27 times in an air circulation oven at 147 ° C. After stretching, the shrinkable film D is peeled off together with the acrylic pressure-sensitive adhesive layer. A retardation film M was produced. The characteristics are shown in Table 1. In this retardation film, the refractive index ellipsoid showed a relationship of nx>nz> ny, and the chromatic dispersion value (D) was 1.08. The physical properties of the shrinkable film D are shown in Table 2.

FIG. 8 is a graph showing the relationship between the in-plane retardation value Re ([590]) of the retardation films obtained in Reference Examples 1 to 12 and the Nz coefficient. FIG. 9 is a graph showing the relationship between the in-plane retardation value Re ([590]) of the retardation films obtained in Reference Examples 1 to 12 and the thickness direction retardation value (Rth [590]). is there. Thus, by employing a specific shrinkable film, a stretching method, and a specific stretching condition, the refractive index ellipsoid has a relationship of nx> nz> ny, and has various retardation values and Nz coefficients. A retardation film could actually be obtained.

<Preparation of polarizing plate>
[Reference Example 14]
A commercially available polarizing plate [Nitto Denko Corporation trade name “SIG1423DU”] was used as the polarizing plate A as it was. The polarizing plate includes a polarizer, a first protective layer disposed on the liquid crystal cell side of the polarizer, and a second protective layer disposed on the side opposite to the liquid crystal cell side. The first protective layer of the polarizing plate A is substantially isotropic, Re [590] is 0.5 nm, and Rth [590] is 1.0 nm.

[Reference Example 15]
A commercially available polarizing plate [Nitto Denko Corporation trade name “TEG1425DU”] was used as the polarizing plate B as it was. The polarizing plate includes a polarizer, a first protective layer disposed on the liquid crystal cell side of the polarizer, and a second protective layer disposed on the side opposite to the liquid crystal cell side. The refractive index ellipsoid of the first protective layer of the polarizing plate B has a relationship of nx≈ny> nz, Re [590] is 1.3 nm, and Rth [590] is 39.8 nm.

<Production of adhesive>
[Reference Example 16]
In a reaction vessel equipped with a cooling tube, a nitrogen introducing tube, a thermometer and a stirrer, 99 parts by weight of butyl acrylate, 1.0 part by weight of 4-hydroxybutyl acrylate, and 2,2-azobisisobutyronitrile were added. 3 parts by weight of ethyl acetate was added to prepare a solution. Next, the solution was stirred while blowing nitrogen gas and polymerized at 60 ° C. for 4 hours to obtain an acrylate copolymer of butyl acrylate and 4-hydroxybutyl acrylate having a weight average molecular weight of 1,650,000.

The acrylate copolymer was further diluted by adding ethyl acetate to prepare a polymer solution (1-A) having a total solid content of 30% by weight. Next, in this polymer solution (1-A), a cross-linking agent containing 0.2 parts by weight of dibenzoyl peroxide with respect to 100 parts by weight of the acrylate copolymer [trade name “NIPER BO— manufactured by Nippon Oil & Fats Co., Ltd.” Y "], 0.02 parts by weight of trimethylolpropane xylylene diisocyanate [trade name" Takenate D110N "manufactured by Mitsui Takeda Chemical Co., Ltd.] with respect to 100 parts by weight of the acrylate copolymer, and 100 weights of the acrylate copolymer. A silane coupling agent containing 0.2 parts by weight of an acetoacetyl group [trade name “A-100” manufactured by Soken Chemical Co., Ltd.] in this order was blended in this order, and a polymer solution (1-B) was prepared. Prepared.

This polymer solution (1-B) is uniformly coated with a fountain coater on the surface of a polyethylene terephthalate film (base material) treated with a silicone release agent, and dried in an air-circulating constant temperature oven at 155 ° C. for 70 seconds. Then, an adhesive layer was formed on the surface of the substrate. Next, the pressure-sensitive adhesive layer formed on the surface of the base material was laminated on the treated surface of the retardation film E that had been subjected to corona treatment (1.2 kW / 15 m / min) to obtain a laminate. This laminate was aged in a 70 ° C. air circulating constant temperature oven for 7 days. The pressure-sensitive adhesive layer thus obtained was referred to as pressure-sensitive adhesive layer A (thickness: 21 μm), and the characteristics are shown in Table 4. In the present invention, instead of the retardation film E, the retardation films A to L shown in Table 2 and the polarizing plate shown in Table 3 are also applied to the pressure-sensitive adhesive layer A by the same method described herein. Can be formed, and equivalent adhesive properties can be obtained.

[Reference Example 17]
Trimethylolpropane xylylene diisocyanate [trade name “Takenate D110N” manufactured by Mitsui Takeda Chemical Co., Ltd.] was used in the same manner as in Reference Example 16 except that 0.12 part by weight was used with respect to 100 parts by weight of the acrylate copolymer. By the method, an adhesive layer B (thickness: 21 μm) was produced. Table 4 shows the characteristics of the pressure-sensitive adhesive layer B. In the present invention, instead of the retardation film E, the pressure-sensitive adhesive layer B is also applied to the retardation films A to L shown in Table 2 and the polarizing plate shown in Table 3 by the same method described herein. Can be formed, and equivalent adhesive properties can be obtained.

[Reference Example 18]
In a reaction vessel equipped with a cooling tube, a nitrogen introduction tube, a thermometer and a stirrer, 100 parts by weight of butyl acrylate, 5 parts by weight of acrylic acid, 0.075 parts by weight of 2-hydroxyethyl acrylate, and 2,2-azo A solution was prepared by adding 0.3 parts by weight of bisisobutyronitrile and ethyl acetate. Next, the solution was stirred while blowing nitrogen gas and subjected to a polymerization reaction at 60 ° C. for 4 hours to obtain an acrylate copolymer of butyl acrylate, acrylic acid and 2-hydroxyethyl acrylate having a weight average molecular weight of 2,200,000.

The acrylate copolymer was further diluted with ethyl acetate to prepare a polymer solution (2-A) having a total solid concentration of 30% by weight. Next, in this polymer solution (2-A), a crosslinking agent having a main component of a compound having an isocyanate group of 0.6 parts by weight with respect to 100 parts by weight of the acrylate copolymer [trade name of Nippon Polyurethane Co., Ltd.] Coronate L "] and 0.075 parts by weight of γ-glycidoxypropyltrimethoxysilane [trade name" KBM-403 "manufactured by Shin-Etsu Chemical Co., Ltd.] with respect to 100 parts by weight of the acrylate copolymer. The polymer solution (2-B) was prepared by blending in order.

This polymer solution (2-B) is uniformly coated with a fountain coater on the surface of a polyethylene terephthalate film (base material) treated with a silicone release agent, and dried in an air-circulating constant temperature oven at 155 ° C. for 70 seconds. Then, an adhesive layer was formed on the surface of the substrate. Next, the pressure-sensitive adhesive layer formed on the surface of the base material was laminated on the treated surface of the retardation film E that had been subjected to corona treatment (1.2 kW / 15 m / min) to obtain a laminate. This laminate was aged in a 23 ° C. air circulating constant temperature oven for 7 days. The pressure-sensitive adhesive layer thus obtained was defined as pressure-sensitive adhesive layer C (thickness: 21 μm), and the characteristics are shown in Table 4. In the present invention, instead of the retardation film E, the retardation films A to L shown in Table 2 and the polarizing plate shown in Table 3 are also applied to the pressure-sensitive adhesive layer C by the same method described herein. Can be formed, and equivalent adhesive properties can be obtained.

<Production of liquid crystal cell>
[Reference Example 19]
Take out the liquid crystal panel from the liquid crystal display device including the IPS mode liquid crystal cell [Toshiba Corporation 32V type wide liquid crystal television product name “FACE (model number: 32LC100)”, screen size: 697 mm × 392 mm)] All of the optical films arranged above and below were removed, and the glass surfaces (front and back) of the liquid crystal cell were washed. The liquid crystal cell thus prepared was designated as liquid crystal cell A.

<Preparation of laminated film>
[Example 1]
A pressure-sensitive adhesive layer A was formed on one surface of the retardation film A obtained in Reference Example 1 in the same manner as in Reference Example 16. Further, an adhesive layer C was formed on one surface of the polarizing plate A obtained in Reference Example 14 by the same method as in Reference Example 18. A laminator is provided on the side opposite to the side of the retardation film A provided with the pressure-sensitive adhesive layer A by peeling off the release liner of the polarizing plate A provided with the pressure-sensitive adhesive layer C. Used to stick. At this time, the retardation film A was laminated so that the slow axis direction of the retardation film A was substantially orthogonal to the absorption axis direction of the polarizing plate A. The laminated film A thus produced comprises a polarizing plate A, an adhesive layer C (second adhesive layer), a retardation film A, and an adhesive layer A (first adhesive layer). Prepare in this order.

[Example 2]
A pressure-sensitive adhesive layer A was formed on one surface of the retardation film E obtained in Reference Example 5 in the same manner as in Reference Example 16. In addition, an adhesive layer C was formed on one surface of the polarizing plate B obtained in Reference Example 15 by the same method as in Reference Example 18. A laminator is provided on the side opposite to the side of the retardation film E provided with the pressure-sensitive adhesive layer A by peeling the release liner of the polarizing plate B including the pressure-sensitive adhesive layer C from the polarizing plate B and the phase difference film E. Used to stick. At this time, the retardation film E was laminated so that the slow axis direction of the retardation film E was substantially orthogonal to the absorption axis direction of the polarizing plate B. The laminated film B thus produced comprises a polarizing plate B, an adhesive layer C (second adhesive layer), a retardation film E, and an adhesive layer A (first adhesive layer). Prepare in this order.

[Comparative Example 1]
A pressure-sensitive adhesive layer A was formed on one surface of the retardation film M obtained in Reference Example 13 by the same method as in Reference Example 16. Further, an adhesive layer C was formed on one surface of the polarizing plate A obtained in Reference Example 14 by the same method as in Reference Example 18. The polarizing plate A and the retardation film M are separated from the release liner of the polarizing plate A provided with the pressure-sensitive adhesive layer C, and a laminator is provided on the side opposite to the side provided with the pressure-sensitive adhesive layer A of the retardation film M. Used to stick. At this time, the retardation film M was laminated so that the slow axis direction of the retardation film M was substantially orthogonal to the absorption axis direction of the polarizing plate A. The laminated film X thus produced comprises a polarizing plate A, an adhesive layer C (second adhesive layer), a retardation film M, and an adhesive layer A (first adhesive layer). Prepare in this order.

[Comparative Example 2]
A pressure-sensitive adhesive layer C was formed on one surface of the retardation film A obtained in Reference Example 1 in the same manner as in Reference Example 18. Further, an adhesive layer C was formed on one surface of the polarizing plate A obtained in Reference Example 14 by the same method as in Reference Example 18. A laminator is provided on the side opposite to the side of the retardation film A provided with the pressure-sensitive adhesive layer C by peeling off the release liner of the polarizing plate A provided with the pressure-sensitive adhesive layer C. Used to stick. At this time, the retardation film A was laminated so that the slow axis direction of the retardation film A was substantially orthogonal to the absorption axis direction of the polarizing plate A. The laminated film Y thus produced comprises a polarizing plate A, an adhesive layer C (second adhesive layer), a retardation film A, and an adhesive layer C (first adhesive layer). Prepare in this order.

<Evaluation of optical characteristics of liquid crystal display device>
[Example 3]
The laminated film A obtained in Example 1 is placed on the viewing side of the liquid crystal cell obtained in Reference Example 19 so that the absorption axis direction of the polarizing plate A is substantially parallel to the long side direction of the liquid crystal cell A. The adhesive layer A was attached. Subsequently, the polarizing plate A ′ obtained in Reference Example 14 is placed on the backlight side of the liquid crystal cell A so that the absorption axis direction of the polarizing plate A ′ is substantially perpendicular to the long side direction of the liquid crystal cell A. The adhesive layer A was attached to the surface. The liquid crystal panel A was combined with a backlight unit [trade name “PRO-LIGHT-BOX 35H” manufactured by Argo Co., Ltd.] to produce a liquid crystal display device A. After 30 minutes have passed since the backlight was turned on, the color shift amount (Δa ^* b ^* ) in the oblique direction and the light leakage amount (Y value) in the oblique direction of the liquid crystal display device A were measured. The characteristics are shown in Table 5. FIG. 10 is a graph showing the Y value of the polar angle 60 ° and the azimuth angles 0 ° to 360 ° of the liquid crystal display device of Example 3 and Comparative Example 3 described later. FIG. 11 is a graph showing Δa ^* b ^* values of polar angle 60 ° and azimuth angles 0 ° to 360 ° of the liquid crystal display device of Example 3 and Comparative Example 3 described later.

The uniformity of the display screen of the liquid crystal display device A was observed 3 hours after the backlight was turned on. As a result, no optical unevenness was observed. The display had good display uniformity over the entire panel surface (indicated as “display uniformity” “◯” in Table 5). In addition, although the laminated film A was used in this example, the same excellent display characteristics and excellent display uniformity can be obtained by using the laminated film B obtained in Example 2 instead. Can be.

[Comparative Example 3]
A liquid crystal panel X and a liquid crystal display device X were produced in the same manner as in Example 4 except that the laminated film X obtained in Comparative Example 1 was used in place of the laminated film A. After 30 minutes have passed since the backlight was turned on, the color shift amount (Δa ^* b ^* ) in the oblique direction and the light leakage amount (Y value) in the oblique direction of the liquid crystal display device A were measured. The characteristics are shown in Table 5. The uniformity of the display screen of the liquid crystal display device X after 3 hours from turning on the backlight was observed. As a result, optical unevenness was observed in the liquid crystal display device X (indicated as “display uniformity” “×” in Table 5).

<Evaluation of light peelability and durability>
[Example 4]
The laminated film B obtained in Example 2 was attached to the surface of an alkali-free glass plate [trade name “1737” manufactured by Corning Co., Ltd.] via the adhesive layer A using a laminator. Subsequently, in order to adhere the pressure-sensitive adhesive layer A to the alkali-free glass plate, an autoclave treatment was performed at 50 ° C. and 5 atm for 15 minutes. The sample produced in this manner was peeled off with light force after 1 hour by human hands, and was able to be peeled off with a light force (in Table 6, “lightly peelable” “◯”). ). Further, neither the pressure-sensitive adhesive layer nor the retardation film remained on the surface of the glass plate. FIG. 12 is a photograph of the surface of the glass plate after the laminated film of Example 3 was peeled off. The results of the peel test are shown in Table 6 together with the results of the adhesive strength and anchoring force of each layer of the laminated film B. In this embodiment, an alkali-free glass plate is used as an alternative to the liquid crystal cell. However, similar results can be obtained by using a liquid crystal cell instead of the alkali-free glass plate.

Another sample produced by the same method was left in a constant temperature bath at 80 ° C. and 90% RH for 500 hours, and then removed from the constant temperature bath to observe the sample. As a result, no peeling or bubbles were generated in the sample (in Table 6, “peeling and generation of bubbles” indicated as “◯”).

[Comparative Example 4]
The laminated film Y obtained in Comparative Example 2 was attached to the surface of an alkali-free glass plate [Corning Corporation trade name “1737”] with a laminator through the adhesive layer C. Subsequently, in order to adhere the pressure-sensitive adhesive layer C to the alkali-free glass plate, an autoclave treatment was performed at 50 ° C. and 5 atm for 15 minutes. The sample produced in this manner was peeled off by a human force after 1 hour by human hands, but could not be peeled with a light force (in Table 6, light peelability “×”). ). When the laminated film was peeled off with a strong force, the laminated film was peeled off at the interface between the polarizing plate and the retardation film, and the pressure-sensitive adhesive layer and the retardation film remained on the surface of the glass plate. FIG. 13 is a photograph of the surface of the glass plate after peeling off the laminated film of Comparative Example 4.

[Evaluation]
As is clear from FIGS. 10 and 11, the liquid crystal display device provided with the laminated film of Example 1 has an extremely small amount of light leakage in the oblique direction and an amount of color shift in the oblique direction, and has good display characteristics. showed that. Further, this liquid crystal display device showed good display uniformity without observing optical unevenness due to distortion. On the other hand, the liquid crystal display device including the laminated film of Comparative Example 1 had a large light leakage amount in the oblique direction and a color shift amount in the oblique direction. In addition, optical irregularities were observed in this liquid crystal display device.

Moreover, the laminated film of Example 2 showed excellent adhesiveness and light peelability without peeling or bubbles even in a high temperature and high humidity environment with respect to an alkali-free glass plate. On the other hand, the laminated film of Comparative Example 2 could not be easily peeled off from the alkali-free glass plate, and the pressure-sensitive adhesive layer and the retardation film remained on the surface of the glass plate after peeling.

As described above, it can be said that the laminated film of the present invention is extremely useful for improving display characteristics of a liquid crystal display device and improving productivity. A liquid crystal display device provided with the laminated film of the present invention is suitably used for a liquid crystal television.

DESCRIPTION OF SYMBOLS 10 Laminated film 20 Polarizing plate 21 Polarizer 22 1st protective layer 23 2nd protective layer 30 Phase difference film 41 1st adhesive layer 42 2nd adhesive layer 50 Liquid crystal cell 51, 51 'Substrate 52 Liquid crystal layer DESCRIPTION OF SYMBOLS 100 Liquid crystal panel 80 Backlight unit 81 Backlight 82 Reflective film 83 Diffusion plate 84 Prism sheet 85 Brightness improvement film 200 Liquid crystal display device 300 Feeding part 310 Iodine aqueous solution bath 320 Bath of aqueous solution containing boric acid and potassium iodide 330 Iodination Aqueous bath 340 containing potassium Drying means 350 Polarizer 360 Winding parts 401, 403, 405 Feeding parts 414, 416, 419 Winding parts 404, 406 Shrinkable films 407, 408 Laminating roll 409 Heating means 501, 506 Feeding part 503 Coater 504 Temperature control hand 507, 508 laminate roll 511 winding-up unit

Claims (20)

A polarizing plate, a retardation film, and a first pressure-sensitive adhesive layer are provided at least in this order,
The polarizing plate includes a polarizer, a first protective layer disposed on a side including the retardation film of the polarizer, and a second disposed on a side opposite to the side including the retardation film of the polarizer. Including a protective layer,
The retardation film is a stretched film containing a norbornene resin,
The first pressure-sensitive adhesive layer is a pressure-sensitive adhesive that can be obtained by crosslinking a composition containing at least a (meth) acrylate-based (co) polymer and a crosslinking agent mainly composed of a diacyl peroxide peroxide. Laminated film containing an agent.   The laminated film according to claim 1, wherein the first protective layer and / or the second protective layer is a polymer film containing a cellulosic resin.   The laminated film according to claim 1 or 2, wherein the first protective layer has substantially optical isotropy. The laminated film according to claim 1, wherein the refractive index ellipsoid of the first protective layer has a relationship of nx≈ny ≧ nz.
Where nx, ny and nz are the refractive index in the slow axis direction, the refractive index in the fast axis direction, and the refractive index in the thickness direction, respectively. The laminated film according to any one of claims 1 to 4, wherein the refractive index ellipsoid of the retardation film has a relationship of nx>nz> ny:
Where nx, ny and nz are the refractive index in the slow axis direction, the refractive index in the fast axis direction, and the refractive index in the thickness direction, respectively. The laminated film according to any one of claims 1 to 5, wherein Re [590] of the retardation film is from 80 nm to 350 nm.
However, Re [590] is an in-plane retardation value measured with light having a wavelength of 590 nm at 23 ° C. The laminated film according to any one of claims 1 to 6, wherein the retardation film has an Nz coefficient of 0.1 to 0.7.
However, the Nz coefficient is a value calculated from the formula: Rth [590] / Re [590], and Re [590] and Rth [590] are surfaces measured with light having a wavelength of 590 nm at 23 ° C., respectively. It is the phase difference value in the inside and the phase difference value in the thickness direction. The laminated film according to any one of claims 1 to 7, wherein an absolute value of a photoelastic coefficient measured with light having a wavelength of 590 nm at 23 ° C of the retardation film is 1 x 10 ^-12 to 10 x 10 ^-12 . The laminated film according to any one of claims 1 to 8, wherein an adhesive force (F _1A ) of the first pressure-sensitive adhesive layer to a glass plate at 23 ° C is 2 N / 25 mm to 10 N / 25 mm.
However, the above adhesive strength is the adhesion when a 25 mm wide laminated film is pressed once on a glass plate with a 2 kg roller, cured at 23 ° C. for 1 hour, and then peeled off at 90 mm direction at 300 mm / min. It is strength. The laminated film according to any one of claims 1 to 9, wherein a throwing force (F _1B ) of the first pressure-sensitive adhesive layer on a retardation film at 23 ° C is 10 N / 25 mm to 40 N / 25 mm.
However, the throwing force is such that a laminate of a 25 mm wide adhesive layer and a retardation film is pressed once on a treated surface of a polyethylene terephthalate film vapor-deposited with indium tin oxide with a 2 kg roller at 23 ° C. It is the adhesive strength when the polyethylene terephthalate film is peeled off at 300 mm / min in the 180 ° direction together with the pressure-sensitive adhesive layer after culturing for 1 hour. Said first anchoring force against the retardation film at 23 ° C. of the adhesive layer and (F _1B), the difference (F _1B of the adhesive force (F _1A) to the glass plate at 23 ° C. of the first adhesive layer - The laminated film according to any one of claims 1 to 10, wherein F _1A ) is 5 N / 25 mm or more.
However, the throwing force is such that a laminate of a 25 mm wide adhesive layer and a retardation film is pressed once on a treated surface of a polyethylene terephthalate film vapor-deposited with indium tin oxide with a 2 kg roller at 23 ° C. It is the adhesive strength when the polyethylene terephthalate film is peeled off at 300 mm / min in the direction of 180 degrees together with the pressure-sensitive adhesive layer after cultivating for 1 hour. The above adhesive strength is obtained by laminating a 25 mm wide laminated film on a glass plate with a 2 kg roller. This is the adhesive strength when the laminated film is peeled off at 300 mm / min in the 90-degree direction after reciprocating pressure bonding and curing at 23 ° C. for 1 hour.   The (meth) acrylate-based (co) polymer is a (meth) acrylate-based monomer having a linear or branched alkyl group having 1 to 8 carbon atoms, and 1 to 1 carbon atoms in which at least one hydrogen atom is substituted with a hydroxyl group. The laminated film according to any one of claims 1 to 11, which is a copolymer with a (meth) acrylate monomer having 8 linear or branched alkyl groups.   The blending amount (weight ratio) of the crosslinking agent containing the peroxide as a main component is 0.01 to 1.0 with respect to the (meth) acrylate-based (co) polymer 100. The laminated film according to any one of the above. The first pressure-sensitive adhesive layer comprises a (meth) acrylate-based (co) polymer, a crosslinking agent mainly composed of a diacyl peroxide peroxide, a compound having an isocyanate group, and a silane coupling agent. A pressure-sensitive adhesive that can be obtained by crosslinking the blended composition at least;
The compounding amount (weight ratio) of the compound having an isocyanate group is 0.005 to 1.0 with respect to the (meth) acrylate-based (co) polymer 100,
The lamination | stacking in any one of Claim 1 to 13 whose compounding quantity (weight ratio) of this silane coupling agent is 0.001-2.0 with respect to this (meth) acrylate type | system | group (co) polymer 100. the film.   The laminated film according to any one of claims 1 to 14, wherein a glass transition temperature (Tg) of the pressure-sensitive adhesive is -70 ° C to -10 ° C.   The laminated film according to any one of claims 1 to 15, wherein a moisture content of the pressure-sensitive adhesive is 1.0% or less.   The laminated film according to any one of claims 1 to 16, wherein the pressure-sensitive adhesive has a gel fraction of 40% to 90%. Further comprising a second pressure-sensitive adhesive layer between the polarizing plate and the retardation film,
The second pressure-sensitive adhesive layer is obtained by crosslinking a composition containing at least a (meth) acrylate-based (co) polymer, a crosslinking agent mainly composed of a compound having an isocyanate group, and a silane coupling agent. The laminated film according to claim 1, comprising a pressure-sensitive adhesive that can be obtained.   A liquid crystal panel comprising at least the laminated film according to claim 1 and a liquid crystal cell.   A liquid crystal display device comprising the liquid crystal panel according to claim 19.

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