JP6199716B2 - Retardation film and liquid crystal display device - Google Patents

Description

  The present invention relates to a retardation film and a liquid crystal display device.

Conventionally, a wide viewing angle liquid crystal system such as an IPS (In-Plane Switching) system and a VA (Vertically Aligned) system has been proposed, and the share of the liquid crystal TV is increasing with the recent increase in demand for liquid crystal televisions.
Each method has improved display quality. However, the solution to the problem of color change (color shift) and light leakage (black luminance) that occurs when observing the liquid crystal cell from an oblique direction is particularly effective. It is requested.
As a technique for solving such a problem, a technique using two types of retardation films having different optical characteristics is known (see, for example, Patent Documents 1 to 3).

JP 2009-053684 A JP 2009-069813 A JP 2009-237421 A

On the other hand, in recent years, liquid crystal display devices have been made thinner, and accordingly, there has been a demand for thinner members (for example, retardation films) used.
Therefore, the present inventors examined thinning of the conventionally known retardation films described in Patent Documents 1 to 3 and the like, and as a result, the liquid crystal display device was reduced in thickness and display performance (color change and light leakage prevention). It was found difficult to achieve a balance with).

  Accordingly, an object of the present invention is to provide a retardation film capable of achieving both reduction in thickness of the device and improvement in display performance when applied to a liquid crystal display device, and a liquid crystal display device using the same.

As a result of diligent research to achieve the above-mentioned problems, the present inventors have found that a resin layer containing a polyvinyl alcohol resin and having a thickness and Re (550) in a specific range, and a liquid crystal layer having a thickness in a predetermined range. By using a retardation film having the above, it was found that the liquid crystal display device can be made thin and the display performance can be improved, and the present invention has been completed.
That is, it has been found that the above object can be achieved by the following configuration.

[1] A retardation film having a resin layer and a liquid crystal layer,
The resin layer is a resin layer containing a polyvinyl alcohol-based resin, having a thickness of 3 μm to 20 μm, and Re (550) of 80 nm to 300 nm,
A retardation film having a liquid crystal layer having a thickness of 5 μm or less.
(However, Re (550) represents in-plane retardation (nm) at a wavelength of 550 nm.)
[2] The position according to [1], wherein the Nz value of the resin layer (where “Nz = Rth (550) / Re (550) +0.5”) satisfies 1.0 and 2.0 or less. Phase difference film.
(However, Re (550) represents in-plane retardation (nm) at a wavelength of 550 nm, and Rth (550) represents retardation in the film thickness direction (nm) at a wavelength of 550 nm.)
[3] The retardation film according to [1] or [2], wherein the liquid crystal layer is a film formed by fixing the alignment state of the liquid crystalline compound.
[4] A liquid crystal display device including a viewing side polarizer, the retardation film according to any one of [1] to [3], and a liquid crystal cell in this order.

[5] The retardation film according to any one of [1] to [3], wherein the optical characteristics of the liquid crystal layer satisfy the following formulas (1-1) and (1-2).
Formula (1-1) 0 nm ≦ Re (550) ≦ 10 nm
Formula (1-2) −200 nm ≦ Rth (550) ≦ −100 nm
(However, Re (550) represents in-plane retardation (nm) at a wavelength of 550 nm, and Rth (550) represents retardation in the film thickness direction (nm) at a wavelength of 550 nm.)
[6] The retardation film according to [5], wherein the liquid crystal layer contains a rod-like liquid crystalline compound in which the liquid crystal layer is vertically aligned.
[7] A liquid crystal display device comprising a viewing side polarizer, the retardation film according to [5] or [6], and a liquid crystal cell in this order.
[8] The liquid crystal display device according to [7], wherein the liquid crystal cell is in an IPS mode.
[9] The liquid crystal display device according to [7] or [8], wherein the total thickness of the viewing side polarizer and the retardation film is 5 μm to 35 μm.
[10] The liquid crystal display device according to any one of [7] to [9], wherein an angle formed between the absorption axis of the viewing side polarizer and the slow axis of the retardation film is 85 ° to 95 °.
[11] The liquid crystal display device according to any one of [7] to [10], wherein the retardation film is disposed such that the viewing side polarizer and the resin layer constituting the retardation film are adjacent to each other.
[12] The liquid crystal display device according to any one of [7] to [9], wherein an angle formed between the absorption axis of the viewing side polarizer and the slow axis of the retardation film is −5 ° to 5 °.
[13] The liquid crystal display device according to any one of [7] to [9] and [12], wherein the retardation film is disposed so that a liquid crystal cell and a resin layer constituting the retardation film are adjacent to each other. .

[14] The retardation film according to any one of [1] to [3], wherein the optical characteristics of the liquid crystal layer satisfy the following formulas (2-1) and (2-2).
Formula (2-1) 60 nm ≦ Re (550) ≦ 180 nm
Formula (2-2) −30 nm ≦ Rth (550) ≦ −90 nm
(However, Re (550) represents in-plane retardation (nm) at a wavelength of 550 nm, and Rth (550) represents retardation in the film thickness direction (nm) at a wavelength of 550 nm.)
[15] A liquid crystal display device having a viewing side polarizer, the retardation film according to [14], and a liquid crystal cell in this order.
[16] The liquid crystal display device according to [15], wherein the liquid crystal cell is in an IPS mode.
[17] The liquid crystal display device according to [15] or [16], wherein the total thickness of the viewing side polarizer and the retardation film is 5 μm to 35 μm.
[18] The liquid crystal display device according to any one of [15] to [17], wherein an angle formed between the absorption axis of the viewing side polarizer and the slow axis of the retardation film is −5 ° to 5 °.
[19] The liquid crystal display device according to any one of [15] to [18], wherein the retardation film is disposed so that a liquid crystal cell and a resin layer constituting the retardation film are adjacent to each other.
[20] The liquid crystal display device according to any one of [15] to [17], wherein an angle formed between the absorption axis of the viewing side polarizer and the slow axis of the retardation film is 85 ° to 95 °.
[21] The retardation film according to any one of [15] to [17] and [20], wherein the retardation film is arranged so that the viewing side polarizer and the resin layer constituting the retardation film are adjacent to each other. Liquid crystal display device.

[22] The retardation film according to any one of [1] to [3], wherein the optical characteristics of the liquid crystal layer satisfy the following formulas (3-1) and (3-2).
Formula (3-1) 0 nm ≦ Re (550) ≦ 10 nm
Formula (3-2) 100 nm ≦ Rth (550) ≦ 200 nm
(However, Re (550) represents in-plane retardation (nm) at a wavelength of 550 nm, and Rth (550) represents retardation in the film thickness direction (nm) at a wavelength of 550 nm.)
[23] A liquid crystal display device having a viewing side polarizer, the retardation film according to [22], and a liquid crystal cell in this order.
[24] The liquid crystal display device according to [23], wherein the liquid crystal cell is in a VA mode.
[25] The liquid crystal display device according to [23] or [24], wherein the total thickness of the viewing side polarizer and the retardation film is 5 μm to 35 μm.
[26] The liquid crystal display device according to any one of [23] to [25], wherein an angle formed between the absorption axis of the viewing side polarizer and the slow axis of the retardation film is 85 ° to 95 °.
[27] The liquid crystal display device according to any one of [23] to [26], wherein the retardation film is arranged so that the viewing side polarizer and the resin layer constituting the retardation film are adjacent to each other.

  ADVANTAGE OF THE INVENTION According to this invention, when applied to a liquid crystal display device, the phase difference film which can make the thickness reduction of a device and the improvement of display performance compatible, and a liquid crystal display device using the same can be provided.

It is typical sectional drawing which shows an example of the phase difference film of this invention. It is typical sectional drawing which shows an example of the 1st aspect of the liquid crystal display device of this invention. It is typical sectional drawing which shows an example of the 2nd aspect of the liquid crystal display device of this invention. It is typical sectional drawing which shows an example of the 3rd aspect of the liquid crystal display device of this invention.

Hereinafter, the present invention will be described in detail.
The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments.
In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
Next, terms used in this specification will be described.

In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at the wavelength λ, respectively.
Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH or KOBRA WR (both manufactured by Oji Scientific Instruments). In selecting the measurement wavelength λnm, the wavelength selection filter can be exchanged manually, or the measurement value can be converted by a program or the like.

Here, when the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method.
Rth (λ) is the film surface when Re (λ) is set to the in-plane slow axis (determined by KOBRA 21ADH or KOBRA WR) as the tilt axis (rotary axis). Measurement is performed at a total of 6 points by injecting light of wavelength λ nm from each inclined direction in steps of 10 degrees from the normal direction to 50 ° on one side with respect to the film normal direction (with any rotation direction as the rotation axis). Then, KOBRA 21ADH or KOBRA WR is calculated based on the measured retardation value, the assumed value of the average refractive index, and the input film thickness value. In the above case, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, retardation at a tilt angle larger than the tilt angle. The value is calculated by KOBRA 21ADH or KOBRA WR after changing its sign to negative. The retardation value is measured from two inclined directions with the slow axis as the tilt axis (rotation axis) (if there is no slow axis, the arbitrary direction in the film plane is the rotation axis). Rth can also be calculated from the following formula (A) and formula (B) based on the value, the assumed value of the average refractive index, and the input film thickness value.

Note that Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. In the formula (A), nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction orthogonal to nx in the plane, and nz is the direction orthogonal to nx and ny. Represents the refractive index.
Rth = ((nx + ny) / 2−nz) × d (B)

On the other hand, when the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film having no so-called optical axis, Rth (λ) is calculated by the following method. The
Rth (λ) is from −50 ° with respect to the film normal direction, with Re (λ) being the in-plane slow axis (determined by KOBRA 21ADH or KOBRA WR) as the tilt axis (rotary axis). Measured at 11 points with light of wavelength λ nm incident in 10 ° steps up to + 50 °, respectively, and based on the measured retardation value, average refractive index assumption and input film thickness value KOBRA 21ADH or KOBRA WR is calculated. In the above measurement, as the assumed value of the average refractive index, values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can be used. If the average refractive index is not known, it can be measured with an Abbe refractometer.
The average refractive index values of main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). By inputting the assumed value of the average refractive index and the film thickness, KOBRA 21ADH or KOBRA WR calculates nx, ny, and nz. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

  In the present specification, “visible light” means 380 nm to 780 nm. Moreover, in this specification, when there is no special mention about a measurement wavelength, a measurement wavelength is 550 nm.

  Further, in this specification, the angle relationship (for example, “orthogonal”, “parallel”, “90 °”, etc.) includes a range of errors allowed in the technical field to which the present invention belongs. Specifically, it means that the angle is within a range of strict angle ± 10 °, and an error from the strict angle is preferably 5 ° or less, and more preferably 3 ° or less.

[Phase difference film]
The retardation film of the present invention is a retardation film having a resin layer and a liquid crystal layer, the resin layer contains a polyvinyl alcohol-based resin, has a thickness of 3 μm to 20 μm, and Re (550) is It is a phase difference film which is a resin layer which is 80 nm-300 nm, and the thickness of a liquid crystal layer is 5 micrometers or less.

FIG. 1 is a cross-sectional view schematically showing an example of the retardation film of the present invention. In addition, the figure in this invention is a schematic diagram, and the relationship of the thickness of each layer, a positional relationship, etc. do not necessarily correspond with an actual thing. The same applies to the other figures.
A retardation film 10 shown in FIG. 1 has a resin layer 12 and a liquid crystal layer 14.
Moreover, the resin layer 12 and the liquid crystal layer 14 may be adjacent as shown in FIG. 1, and may be laminated | stacked through the adhesive agent and adhesive which are not shown in figure.
Below, each layer which comprises the retardation film of this invention is explained in full detail.

<Resin layer>
The resin layer of the retardation film of the present invention is a resin layer containing a polyvinyl alcohol (PVA) resin, having a thickness of 3 μm to 20 μm, and Re (550) of 80 nm to 300 nm.
In the present invention, by using a retardation film having a liquid crystal layer, which will be described later, together with such a resin layer, both thinning of the liquid crystal display device and improvement of display performance can be achieved.
Although this is not clear in detail, the present inventors presume as follows.
Polyvinyl alcohol resin contains a large amount of hydroxyl groups in the molecule, and since these hydroxyl groups easily form hydrogen bonds between molecules to suppress molecular movement of the polymer chain, it contains polyvinyl alcohol resin. The resin layer is considered to be less susceptible to orientation relaxation than a resin layer containing another polymer resin such as a cellulose acylate resin, an acrylic resin, or a cycloolefin resin.
As a result, the resin layer containing a polyvinyl alcohol-based resin maintains a high degree of orientation and can maintain a high birefringence even if it is a thin film, thus achieving both thinning of the liquid crystal display device and improvement of display performance. I think it can be done.

  Moreover, since the resin layer containing such a polyvinyl alcohol-type resin is conventionally utilized as a liquid crystal alignment film, it can be utilized as an alignment film for forming a liquid crystal layer described later.

  The content of the polyvinyl alcohol resin in the resin layer (the total content in the embodiment containing two or more polyvinyl alcohol resins) is preferably 50% by mass or more of the total raw materials (excluding the solvent), More preferably, it is 70-99.5 mass%, and it is still more preferable that it is 80-99 mass%.

  The polyvinyl alcohol-based resin is not particularly limited, and may be formed using one kind of polyvinyl alcohol-based resin, and any of a plurality of types (for example, polymerization degree, saponification degree, presence / absence of chemical modification, type of chemical modification, etc.) Alternatively, it may be formed using a plurality of types of polyvinyl alcohol resins that differ in one or more points.

  Specific examples of the polyvinyl alcohol-based resin include unmodified PVA described in paragraphs [0024] to [0048] of Patent Document 3 (JP 2009-237421 A) and modified polyvinyl having a polymerizable functional group in the molecule. Alcohol etc. are mentioned.

The said resin layer may contain the additive in the range which does not impair the effect of this invention other than polyvinyl alcohol-type resin. For example, a crosslinking agent can be used to cure a composition containing a polyvinyl alcohol-based resin to obtain a film having water resistance.
Examples of the crosslinking agent include boric acid, aldehydes, N-methylol compounds, dioxane derivatives, compounds that act by activating carboxyl groups, active vinyl compounds, active halogen compounds, isoxazole, and dialdehyde starch. More specifically, compounds described in paragraphs [0023] to [0024] of JP-A No. 2002-62426 may be mentioned. Aldehydes having high reaction activity, particularly glutaraldehyde are preferred.

  In the present invention, the Nz value of the resin layer (where “Nz = Rth (550) / Re (550) +0.5” is represented for the reason that display performance (particularly, color change prevention performance) is further improved. .) Is preferably more than 1.0 and not more than 2.0, more preferably 1.02 to 1.8, and still more preferably 1.02 to 1.6.

In addition, the thickness of the resin layer is preferably 3 μm to 15 μm, more preferably 4 μm to 12 μm, from the viewpoint of further improving display performance.
Further, Re (550) of the resin layer is preferably from 80 nm to 150 nm, more preferably from 80 nm to 120 nm, from the viewpoint of further improving the display performance.
Similarly, Rth (550) of the resin layer is preferably 40 nm to 225 nm, more preferably 40 nm to 150 nm, from the viewpoint of further improving display performance.

  In the present invention, the method for forming the resin layer is not particularly limited. For example, a composition containing a polyvinyl alcohol resin is a base material (for example, a polyethylene terephthalate (PET) base material, a polypropylene (PP) base material, etc.). Examples of the method include a method in which a film-like product is formed after being applied on top and dried, and then subjected to stretching treatment.

Here, the stretching treatment is preferably performed by uniaxial stretching.
Uniaxial stretching can employ either longitudinal stretching performed in the longitudinal direction of the film-like product or transverse stretching conducted in the width direction of the film-like product. Examples of the transverse stretching method include a fixed end uniaxial stretching method in which one end is fixed via a tenter, and a free end uniaxial stretching method in which one end is not fixed. Examples of the longitudinal stretching method include an inter-roll stretching method, a compression stretching method, and a stretching method using a tenter.
Further, the stretching treatment includes biaxial stretching (for example, a method of stretching biaxially in the plane direction, a method of stretching uniaxially or biaxially in the plane direction, and stretching in the thickness direction, etc.), oblique stretching; Can be done.

<Liquid crystal layer>
The liquid crystal layer included in the retardation film of the present invention is a liquid crystal layer having a thickness of 5 μm or less.
In the present invention, such a liquid crystal layer is preferably formed by fixing the alignment state of the liquid crystal compound. Specifically, a liquid crystal compound having an unsaturated double bond (polymerizable group) is used. A method of immobilizing this liquid crystalline compound by polymerization is preferably exemplified. Note that the liquid crystal layer may have a single-layer structure or a stacked structure.
The kind of unsaturated double bond contained in the liquid crystal compound is not particularly limited, and a functional group capable of addition polymerization reaction is preferable, and a polymerizable ethylenically unsaturated group or a ring polymerizable group is preferable. More specifically, a (meth) acryloyl group, a vinyl group, a styryl group, an allyl group, etc. are mentioned preferably, and a (meth) acryloyl group is more preferable.

In general, liquid crystal compounds can be classified into a rod-shaped type and a disk-shaped type based on their shapes. In addition, there are low and high molecular types, respectively. Polymer generally refers to a polymer having a degree of polymerization of 100 or more (Polymer Physics / Phase Transition Dynamics, Masao Doi, 2 pages, Iwanami Shoten, 1992). In the present invention, any liquid crystalline compound can be used, but a rod-like liquid crystalline compound (nematic liquid crystalline compound, smectic liquid crystalline compound, cholesteric liquid crystalline compound) or discotic liquid crystalline compound (discotic liquid crystalline compound) is used. It is preferable to use it. Two or more kinds of rod-like liquid crystalline compounds, two or more kinds of disc-like liquid crystalline compounds, or a mixture of a rod-like liquid crystalline compound and a disk-like liquid crystalline compound may be used. In order to fix the liquid crystalline compound, it is more preferable to use a rod-like liquid crystalline compound having a polymerizable group or a discotic liquid crystalline compound, and the liquid crystalline compound has 2 polymerizable groups in one molecule. It is more preferable to have the above. In the case where the liquid crystal compound is a mixture of two or more, it is preferable that at least one liquid crystal compound has two or more polymerizable groups in one molecule.
As the rod-like liquid crystalline compound, for example, those described in claim 1 of JP-T-11-53019 and paragraphs [0026] to [0098] of JP-A-2005-289980 can be preferably used. As the tick liquid crystal compound, for example, those described in paragraphs [0020] to [0067] of JP-A-2007-108732 and paragraphs [0013] to [0108] of JP-A-2010-244038 are preferably used. However, it is not limited to these.

  In addition to the liquid crystal compound, the liquid crystal layer may use an additive (alignment control agent) that promotes horizontal alignment and vertical alignment in order to make the liquid crystal compound in a horizontal alignment and vertical alignment state. Various known additives can be used as the additive.

  Further, the thickness of the liquid crystal layer is preferably 0.5 μm to 5 μm, more preferably 1 μm to 4 μm, from the viewpoint of stabilizing the performance to be expressed.

In the present invention, the optical characteristics of the liquid crystal layer are that, in the first aspect of the liquid crystal display device of the present invention described later, light leakage and color change are suppressed at a higher level, and the display performance is further improved. It is preferable that the following formula (1-1) and formula (1-2) are satisfied.
Formula (1-1) 0 nm ≦ Re (550) ≦ 10 nm
Formula (1-2) −200 nm ≦ Rth (550) ≦ −100 nm
Among these, from the viewpoint of further improving the display performance of the liquid crystal display device, Re (550) is preferably 7 nm or less, more preferably 5 nm or less, and Rth (550) is preferably −190 nm to −110 nm, and −180 nm to -120 nm is more preferable.

  Here, from the viewpoint of satisfying the above formulas (1-1) and (1-2), the liquid crystal layer is a vertically aligned rod-like liquid crystal as shown in a liquid crystal display device (first embodiment) described later. It is preferable to contain a functional compound.

Further, the optical characteristics of the liquid crystal layer are expressed by the following formulas in the second aspect of the liquid crystal display device of the present invention described later, because light leakage and color change are suppressed at a higher level and display performance is further improved. It is preferable to satisfy (2-1) and formula (2-2).
Formula (2-1) 60 nm ≦ Re (550) ≦ 180 nm
Formula (2-2) −30 nm ≦ Rth (550) ≦ −90 nm
Among these, from the viewpoint of further improving the display performance of the liquid crystal display device, Re (550) is preferably 70 nm to 160 nm, more preferably 80 nm to 140 nm, and Rth (550) is preferably −80 nm to −35 nm, − 70 nm to -40 nm is more preferable.

  Here, from the viewpoint of satisfying the above formulas (2-1) and (2-2), the liquid crystal layer is a vertically aligned disc shape as shown in a liquid crystal display device (second embodiment) described later. It preferably contains a liquid crystal compound.

Further, the optical characteristics of the liquid crystal layer are expressed by the following formulas in the third aspect of the liquid crystal display device of the present invention to be described later, because light leakage and color change are suppressed at a higher level and display performance is further improved. It is preferable to satisfy (3-1) and formula (3-2).
Formula (3-1) 0 nm ≦ Re (550) ≦ 10 nm
Formula (3-2) 100 nm ≦ Rth (550) ≦ 200 nm
Among these, from the viewpoint of further improving the display performance of the liquid crystal display device, Re (550) is preferably 7 nm or less, more preferably 5 nm or less, and Rth (550) is preferably 120 nm to 190 nm, more preferably 140 nm to 180 nm. preferable.

  Here, from the viewpoint of satisfying the above formulas (3-1) and (3-2), the liquid crystal layer is a horizontally-aligned disk shape as shown in a liquid crystal display device (third mode) described later. It preferably contains a liquid crystal compound.

<Adhesives and adhesives>
In the present invention, the above-described interlayer between the resin layer and the liquid crystal layer may be laminated via an adhesive or an adhesive.
The pressure-sensitive adhesive and adhesive used in the present invention are not particularly limited, and a commonly used pressure-sensitive adhesive (for example, acrylic pressure-sensitive adhesive) and an adhesive (for example, polyvinyl alcohol-based adhesive) can be used.

[Liquid Crystal Display]
The liquid crystal display device of the present invention is a liquid crystal display device having a viewing side polarizer, the above-described retardation film of the present invention, and a liquid crystal cell in this order.
The liquid crystal display device of the present invention can achieve both reduction in thickness and improvement in display performance by including the retardation film having the resin layer described above.
In the liquid crystal display device of the present invention, the total thickness of the viewing side polarizer and the retardation film is preferably 5 μm to 35 μm, more preferably 6 μm to 25 μm, and further preferably 7 μm to 20 μm. preferable.
Below, each structure of the liquid crystal display device of this invention is explained in full detail.

<Viewing side polarizer>
The viewing side polarizer of the liquid crystal display device of the present invention is not particularly limited, and a commonly used polarizer can be used.
Examples of polarizers include dichroic iodine and dichroic dyes on hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymer partially saponified films. Examples include those obtained by adsorbing substances and uniaxially stretched; polyene-based oriented films such as dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride.
Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic substance such as iodine is preferable.

  The thickness of the viewing side polarizer is not particularly limited, but is preferably 25 μm or less, more preferably 15 μm or less, for the reason that the thickness of the liquid crystal display device can be further reduced. Although a minimum is not specifically limited, Usually, it is 1 micrometer or more.

(Protective film)
In this invention, you may provide the protective film as arbitrary structures in the surface on the opposite side to the side in which the phase difference film of the said visual recognition side polarizer was provided.
Here, specifically, as the protective film, for example, films of cellulose acylate, polycarbonate, polysulfone, polyethersulfone, polyacrylate and polymethacrylate, cyclic polyolefin, polyolefin, polyamide, polystyrene, polyester, and the like may be used. it can.

<Phase difference film>
The retardation film of the liquid crystal display device of the present invention is the above-described retardation film of the present invention.
Here, as shown also in the specific mode (especially FIG. 2 and 3) of the liquid crystal display device mentioned later, as for a retardation film, the said visual recognition side polarizer and the resin layer which comprises retardation film are adjacent. It may be arrange | positioned and may arrange | position so that the liquid crystal cell mentioned later and the resin layer which comprises retardation film may adjoin. In particular, the former arrangement is preferred for reasons such as good adhesion between the viewing-side polarizer and the retardation film.

<Liquid crystal cell>
The liquid crystal cell which the liquid crystal display device of this invention has is not specifically limited, The thing of various well-known modes can be used.
Specific examples of the mode include IPS mode, VA mode, TN mode, OCB mode, and ECB mode.
Among these, from the viewpoint of having good visibility without using a retardation film and making the liquid crystal display device thinner, the IPS mode and the VA mode are used as shown in the specific embodiment of the liquid crystal display device described later. preferable.

<Backlight side polarizer>
The liquid crystal display device of the present invention has a backlight side polarizer on the side (backlight side) opposite to the side where the retardation film of the liquid crystal cell is provided.
Here, the backlight side polarizer and the viewing side polarizer are a pair of polarizers arranged with the liquid crystal cell sandwiched therebetween, and are arranged so that the absorption axes thereof are orthogonal to each other.
Moreover, a backlight side polarizer is not specifically limited, The polarizer used normally can be used and the example similar to the said visual recognition side polarizer is mentioned.
Moreover, the backlight side polarizer may have a protective film in the backlight side similarly to the visual recognition side polarizer.

<First aspect>
FIG. 2 is a cross-sectional view schematically showing an example of the first aspect of the liquid crystal display device of the present invention.
A liquid crystal display device 20 shown in FIG. 2A includes a viewing side polarizer 22, a retardation film 10 [reference numeral 12: resin layer, reference numeral 14 a: liquid crystal layer (vertically aligned rod-like liquid crystalline compound)], and a liquid crystal cell 24. The liquid crystal display device includes the (IPS cell) and the backlight side polarizer 26 in this order.
Moreover, the liquid crystal display device 20 shown in FIG. 2 (B) has a liquid crystal layer (vertically aligned rod-like liquid crystalline compound) 14a and a resin from the viewing side in the layer configuration of the retardation film 10 in the embodiment shown in FIG. It is the aspect changed in order of the layer 12.
2 and FIGS. 3 and 4 to be described later, “⇔” and “「 ”indicate the directions of the absorption axis or slow axis in each displayed layer, and“ ⇔ ”and“ 「” are orthogonal to each other. Represents that

  Here, in the aspect shown in FIG. 2A, that is, in the aspect in which the viewing side polarizer 22 and the resin layer 12 constituting the retardation film 10 are adjacent to each other, the absorption of the viewing side polarizer 22 is performed. The angle formed between the axis and the slow axis of the retardation film 10 is preferably 85 ° to 95 °.

  On the other hand, in the embodiment shown in FIG. 2B, that is, in the embodiment in which the liquid crystal cell 24 and the resin layer 12 constituting the retardation film 10 are arranged adjacent to each other, the absorption axis and position of the viewing-side polarizer 22 are changed. The angle formed with the slow axis of the retardation film 10 is preferably −5 ° to 5 °.

<Second aspect>
FIG. 3 is a cross-sectional view schematically showing an example of the second aspect of the liquid crystal display device of the present invention.
A liquid crystal display device 30 shown in FIG. 3A includes a viewing-side polarizer 22, a retardation film 10 (reference numeral 14b: liquid crystal layer (vertical alignment discotic liquid crystalline compound), reference numeral 12: resin layer), and a liquid crystal cell. This is a liquid crystal display device having 24 (IPS cell) and the backlight side polarizer 26 in this order.
In addition, the liquid crystal display device 30 shown in FIG. 3B has a resin layer 12 and a liquid crystal layer (vertically aligned disk-like liquid crystal properties) from the viewing side in the layer configuration of the retardation film 10 in the embodiment shown in FIG. Compound) 14b and the order of modification.

  Here, in the embodiment shown in FIG. 3A, that is, in the embodiment in which the liquid crystal cell 24 and the resin layer 12 constituting the retardation film 10 are arranged adjacent to each other, the absorption axis of the viewing-side polarizer 22 and The angle formed with the slow axis of the retardation film 10 is preferably −5 ° to 5 °.

  On the other hand, in the embodiment shown in FIG. 3B, that is, in the embodiment in which the viewing side polarizer 22 and the resin layer 12 constituting the retardation film 10 are disposed adjacent to each other, the absorption axis of the viewing side polarizer 22. And an angle formed by the slow axis of the retardation film 10 is preferably 85 ° to 95 °.

<Third Aspect>
FIG. 4 is a cross-sectional view schematically showing an example of the third aspect of the liquid crystal display device of the present invention.
The liquid crystal display device 40 shown in FIG. 4 includes a viewing side polarizer 22, a retardation film 10 [reference numeral 12: resin layer, reference numeral 14c: liquid crystal layer (horizontal alignment discotic liquid crystalline compound)], and a liquid crystal cell 24 (VA). Cell) and a backlight side polarizer 26 in this order.

  The present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

[Example 1]
<Preparation of resin layer (optical compensation layer 1)>
6 mol% of isophthalic acid was copolymerized to produce an amorphous ester-based thermoplastic resin base material (hereinafter also simply referred to as “resin base material”) made of isophthalic acid-copolymerized polyethylene terephthalate.
A polyvinyl alcohol (PVA) resin layer having a film thickness of 13 μm was formed on the resin substrate by applying a solution containing a polyvinyl alcohol-based resin.
Subsequently, the resin base material and the PVA resin layer were integrally stretched at 90 ° C. by 30% to prepare an optical compensation layer 1 (thickness: 10 μm) made of the PVA resin layer on the resin base material.
About the film in which the optical compensation layer 1 was produced, using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.), the dependency of retardation on the light incident angle was measured, and the resin substrate was measured in advance. When the optical characteristics of the optical compensation layer 1 alone were calculated by subtracting this contribution, it was confirmed that Re of the PVA resin layer was 100 nm and Rth was 100 nm.

<Preparation of liquid crystal layer (optical compensation layer 2)>
Next, 3.8 g of methyl ethyl ketone, 3.8 g of the following rod-like liquid crystal compound 1, 0.06 g of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy), sensitizer (Kayacure DETX, Nippon Kayaku Co., Ltd.) )) And 0.02 g of the following air interface side vertical alignment agent were dissolved to prepare a solution.
Next, this solution was applied to the surface of the PVA resin layer (optical compensation layer 1) on the previously prepared resin substrate using a # 3.4 number wire bar. After application, the rod-shaped liquid crystal compound 1 was aligned by heating in a thermostatic bath at 100 ° C. for 2 minutes.
Next, UV irradiation was performed at 80 ° C. with a 120 W / cm high pressure mercury lamp for 20 seconds to crosslink the rod-like liquid crystal compound 1 to form a liquid crystal layer (optical compensation layer 2, thickness: 1 μm), and then allowed to cool to room temperature. The phase difference film 1 of Example 1 was produced by removing the amorphous ester thermoplastic resin substrate used as the resin substrate.

Rod-like liquid crystalline compound 1:

  About the produced retardation film 1, the automatic birefringence meter (KOBRA-21ADH, Oji Scientific Instruments Co., Ltd. product) was used to measure the light incident angle dependency of retardation, and the PVA resin layer ( By subtracting the contribution of the optical compensation layer 1), the optical characteristics of only the liquid crystal layer (optical compensation layer 2) were calculated. As a result, Re was 0 nm and Rth was -155 nm. It was confirmed that they were oriented.

[Example 2]
A retardation film 2 was produced in the same manner as in Example 1 except that the wire bar count at the production of the liquid crystal layer (optical compensation layer 2) was changed to # 3.0.
As for the optical characteristics of the liquid crystal layer (optical compensation layer 2) in the produced retardation film 2, Re was 0 nm and Rth was -140 nm.

[Example 3]
<Preparation of resin layer (optical compensation layer 1)>
A resin base material was produced in the same manner as in Example 1.
A polyvinyl alcohol (PVA) resin layer having a film thickness of 13 μm was formed on the resin substrate by applying a solution containing a polyvinyl alcohol-based resin.
Subsequently, the resin base material and the PVA resin layer were integrally stretched at 90 ° C. by 60% to prepare an optical compensation layer 1 (thickness: 5 μm) composed of the PVA resin layer on the resin base material.
When the optical characteristics of the film from which the optical compensation layer 1 was produced were calculated in the same manner as in Example 1, it was confirmed that Re of the PVA resin layer was 80 nm and Rth was 42 nm.

<Preparation of liquid crystal layer (optical compensation layer 2)>
First, the rubbing process was performed to the PVA resin layer (optical compensation layer 1) produced previously. At this time, the rotation axis of the rubbing roller was orthogonal to the film stretching direction.
Next, a coating liquid A containing a discotic liquid crystal compound having the following composition was applied to the surface of the PVA resin layer (optical compensation layer 1) subjected to rubbing treatment using a # 1.7th wire bar. After coating, the coating film was heated for 90 seconds with warm air at 120 ° C. to dry the solvent of the coating film and to mature the orientation of the discotic liquid crystal compound.
Next, UV irradiation is performed at 80 ° C. to fix the orientation of the liquid crystal compound, and after preparing a liquid crystal layer (optical compensation layer 2, thickness: 1 μm), the mixture is allowed to cool to room temperature and then used as a resin substrate. The retardation film 3 of Example 3 was produced by removing the amorphous ester thermoplastic resin base material.

(Composition of coating liquid A)
-100 parts by weight of the following discotic liquid crystal compound-3 parts by weight of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Japan) 1 part by weight of a sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 1 part by mass of the pyridinium salt 0.4 parts by mass of the following fluoropolymer (FP1) 252 parts by mass of methyl ethyl ketone

The direction of the slow axis of the liquid crystal layer (optical compensation layer 2) in the produced retardation film 3 was orthogonal to the rotation axis of the rubbing roller. That is, the slow axis was parallel to the stretching direction of the resin base material and the PVA resin layer.
Separately, instead of the resin base material and the PVA resin layer, a layer containing the discotic liquid crystal compound is formed using a glass substrate as a support, and Re (0 °), Re (40 °) and Re ( −40 °) was measured using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments), and they were 89.7 nm, 82.2 nm, and 82.1 nm, respectively. Re (°) represents an incident angle with the normal direction of the sample surface being 0 °.
From these results, the average tilt angle of the disc surface of the discotic liquid crystal compound with respect to the film surface was 90 °, and it was confirmed that the discotic liquid crystal compound was aligned perpendicular to the film surface. The formed liquid crystal layer (optical compensation layer 2) had a thickness of 1 μm, Re of 90 nm, and Rth of −45 nm.

[Example 4]
A retardation film 4 was produced in the same manner as in Example 3 except that the wire bar count at the production of the liquid crystal layer (optical compensation layer 2) was changed to # 2.1.
The optical properties of the produced retardation film 4 are Re (0 °), Re (40 °), and Re (−40 °) of 125.2 nm, 106.0 nm, and 105.9 nm, respectively. The average tilt angle of the disc surface with respect to the film surface was 90 °, and it was confirmed that the discotic liquid crystal compound was aligned perpendicular to the film surface. The formed liquid crystal layer (optical compensation layer 2) had a thickness of 1 μm, Re of 115 nm, and Rth of −58 nm.

[Example 5]
<Preparation of resin layer (optical compensation layer 1)>
A resin base material was produced in the same manner as in Example 1.
On this resin base material, the polyvinyl alcohol (PVA) resin layer with a film thickness of 14 micrometers was formed by apply | coating the solution containing polyvinyl alcohol-type resin.
Subsequently, the optical compensation layer 1 (thickness: 11 μm) composed of the PVA resin layer was formed on the resin base material by stretching the resin base material and the PVA resin layer integrally at 90 ° C. for 30%.
When the optical characteristics of the film from which the optical compensation layer 1 was produced were calculated in the same manner as in Example 1, it was confirmed that the Re of the PVA resin layer was 110 nm and Rth was 110 nm.

<Preparation of liquid crystal layer (optical compensation layer 2)>
The following compounds 3-1 to 3-6 were dissolved in methyl ethyl ketone to prepare a coating solution so that the solid concentration was 36.2%.
(Composition of coating solution)
Polymerizable liquid crystal compound 3-1 91.0 parts by mass Compound 3-2 9.0 parts by mass Polymerization initiator: Compound 3-3 3.0 parts by mass Polymerization initiator: Compound 3-4 1.0 Part by mass / Fluorine-containing surfactant: Compound 3-5 0.8 part by mass / Adhesion improver: Compound 3-6 0.5 part by mass

The prepared coating solution was applied to the surface of the previously stretched PVA resin layer using a # 4.4th wire bar and dried. The polymerizable liquid crystal compound 3-1 was aligned by heating at 70 ° C. for 90 seconds. Thereafter, 290 mJ / cm ² of ultraviolet light is immediately irradiated under the temperature condition of 70 ° C. to polymerize the polymerizable liquid crystal compound 3-1, fix the alignment state, and then the liquid crystal layer (optical compensation layer 2, thickness) : 2 μm), and after cooling to room temperature, the amorphous ester thermoplastic resin base material used as the resin base material was removed to prepare the retardation film 5 of Example 5.
Regarding the optical properties of the liquid crystal layer (optical compensation layer 2) in the produced retardation film 5, Re was 0 nm and Rth was 160 nm.

[Comparative Example 1]
<Preparation of resin layer (optical compensation layer 1)>
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution B.
(Composition of cellulose acylate solution B)
Cellulose acetate (degree of substitution 2.46) 100.0 parts by mass Compound A * 1 19.0 parts by mass Methylene chloride 365.5 parts by mass Methanol 54.6 parts by mass * 1: Compound A is terephthalic acid / succinic acid It represents an acid / propylene glycol / ethylene glycol copolymer (copolymerization ratio [mol%] = 27.5 / 22.5 / 25/25).

The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution C.
(Composition of cellulose acylate solution C)
Cellulose acetate (degree of substitution 2.79) 100.0 parts by mass Compound A * 1 11.0 parts by mass Silica fine particles R972 (manufactured by Nippon Aerosil) 0.15 parts by mass Methylene chloride 395.0 parts by mass Methanol 59 0.0 part by mass * 1: Compound A represents a terephthalic acid / succinic acid / propylene glycol / ethylene glycol copolymer (copolymerization ratio [mol%] = 27.5 / 22.5 / 25/25).

The cellulose acylate solution B was cast so as to be a core layer having a thickness of 90 μm, and the cellulose acylate solution C was cast so as to be a skin A layer having a thickness of 2 μm and a skin B layer having a thickness of 2 μm.
The obtained web (film) was peeled from the band, dried and wound up. At this time, the residual solvent amount with respect to the mass of the entire film was 0 to 0.5%.
Subsequently, the said film was sent out and 75% of TD stretching was performed at 190 degreeC with the tenter, and the resin layer (optical compensation layer 1) with a film thickness of 40 micrometers was produced. The optical characteristics were measured, and it was confirmed that Re was 100 nm and Rth was 100 nm.

<Preparation of liquid crystal layer (optical compensation layer 2)>
The surface of the resin layer (optical compensation layer 1) produced above was saponified, and a commercially available vertical alignment film (JALS-204R, manufactured by Nippon Synthetic Rubber Co., Ltd.) was diluted 1: 1 with methyl ethyl ketone on this film. After that, 2.4 mL / m ^{2 was} applied with a wire bar coater. Immediately, it was dried with warm air of 120 ° C. for 120 seconds.
Next, 3.8 g of the following rod-shaped liquid crystal compound 2, 0.06 g of photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy), 0.02 g of sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.), A solution prepared by dissolving 0.002 g of the air interface side vertical alignment agent in 9.2 g of methyl ethyl ketone was prepared.
This solution was applied to the alignment film side of the film on which the alignment film was formed with a # 3.4 count wire bar. This was affixed to a metal frame and heated in a constant temperature bath at 100 ° C. for 2 minutes to align the rod-like liquid crystal compound.
Next, UV irradiation was performed at 80 ° C. with a 120 W / cm high-pressure mercury lamp for 20 seconds to crosslink the rod-like liquid crystal compound to produce a liquid crystal layer (optical compensation layer 2), and then allowed to cool to room temperature. A retardation film 6 was produced.

Rod-like liquid crystalline compound 2:

  About the produced phase difference film 6, the light incident angle dependence of retardation was measured using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments), and the cellulose acylate ( TAC) By calculating the optical characteristics of only the liquid crystal layer (optical compensation layer 2) by subtracting the contribution of the resin layer (optical compensation layer 1), Re is 0 nm and Rth is -155 nm. It was confirmed that the rod-like liquid crystal was aligned substantially vertically.

[Comparative Example 2]
A retardation film 7 was produced by the same means as in Comparative Example 1 except that the wire bar count at the production of the liquid crystal layer (optical compensation layer 2) was changed to # 3.0.
As for the optical characteristics of the liquid crystal layer (optical compensation layer 2) in the produced retardation film 7, Re was 0 nm and Rth was -140 nm.

[Comparative Examples 3 and 4]
<Preparation of resin layer (optical compensation layer 1)>
Cellulose acylate was synthesized by the method described in JP-A-10-45804 and JP-A-08-231761, and the degree of substitution was measured.
Specifically, sulfuric acid (7.8 parts by mass with respect to 100 parts by mass of cellulose) was added as a catalyst, a carboxylic acid serving as a raw material for the acyl substituent was added, and an acylation reaction was performed at 40 ° C. At this time, the kind and substitution degree of the acyl group were adjusted by adjusting the kind and amount of the carboxylic acid. Moreover, it age | cure | ripened at 40 degreeC after acylation. Further, the low molecular weight component of the cellulose acylate was removed by washing with acetone.

(Preparation of cellulose acylate solution for low substitution layer)
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution.
The amount of the solvent (methylene chloride and methanol) was appropriately adjusted so that the solid content concentration of each cellulose acylate solution would be the value described in the following composition.
-------------------------------------------------- ------------------------
Cellulose acetate (degree of substitution 2.45) 100.0 parts by mass The following additives (polycondensed ester of carboxylic acid and diol) 18.5 parts by mass Methylene chloride 365.5 parts by mass Methanol 54.6 parts by mass
-------------------------------------------------- ------------------------

(Preparation of cellulose acylate solution for high substitution layer)
The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution.
The amount of the solvent (methylene chloride and methanol) was appropriately adjusted so that the solid content concentration of each cellulose acylate solution had the following value.
-------------------------------------------------- ------------------------
Cellulose acetate (degree of substitution 2.79) 100.0 parts by mass The following additives (polycondensation ester of carboxylic acid and diol) 11.3 parts by mass Silica fine particles R972 (manufactured by Nippon Aerosil) 0.15 parts by mass Methylene chloride 395.0 parts by mass-Methanol 59.0 parts by mass
-------------------------------------------------- ------------------------

  Polycondensation ester: Polycondensation ester of terephthalic acid or succinic acid as dicarboxylic acid with ethylene glycol or 1,2-propylene glycol as diol (terephthalic acid: phthalic acid: ethylene glycol: 1,2-propylene glycol = 55 : 45: 50: 50 (molar ratio)) (terminal: acetyl group, molecular weight 800)

(Preparation of cellulose acylate film)
The cellulose acylate solution for the low substitution layer is a core layer having a thickness of 30 μm, and the cellulose acylate solution for the high substitution layer is a skin A layer and a skin B layer having a thickness of 2 μm, respectively. Casted. The obtained web (film) was peeled from the band, sandwiched between clips, and stretched by 10% using a tenter at 140 ° C. when the amount of residual solvent relative to the total mass of the film was 20 to 5%. Thereafter, the clip was removed from the film and dried at 130 ° C. for 20 minutes, and then further stretched again by 17% at 170 ° C. using a tenter.
The residual solvent amount was determined according to the following formula.
Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M is a mass of the web at an arbitrary time point, and N is a mass when the web of which M is measured is dried at 120 ° C. for 2 hours.
Thus, resin layers (optical compensation layer 1, film thickness: 34 μm) of Comparative Examples 3 and 4 were obtained. The optical characteristics were measured, and it was confirmed that Re was 30 nm and Rth was 75 nm.

<Preparation of liquid crystal layer (optical compensation layer 2)>
The surface of the resin layer (optical compensation layer 1) produced above was subjected to saponification treatment, and an alignment film coating solution having the following composition was continuously applied onto this film with a # 14 wire bar. Drying was performed with warm air of 60 ° C. for 60 seconds, and further with warm air of 100 ° C. for 120 seconds.
(Composition of alignment film coating solution)
-10 parts by weight of the following modified polyvinyl alcohol-371 parts by weight of water-119 parts by weight of methanol-0.5 parts by weight of glutaraldehyde-0.3 parts by weight of a photopolymerization initiator (Irgacure 2959, manufactured by Ciba Japan)

  Subsequently, the alignment film produced above was continuously rubbed. At this time, the longitudinal direction of the long film and the transport direction were parallel, and the rotation axis of the rubbing roller was orthogonal to the film longitudinal direction.

Next, a discotic liquid crystalline compound was applied on the rubbed alignment film.
Specifically, for Comparative Example 3, a retardation film was obtained by the same means as in Example 3 except that the wire bar count during the production of the liquid crystal layer (optical compensation layer 2) was changed to # 2.3. 8 was produced. The formed liquid crystal layer (optical compensation layer 2) had a thickness of 1 μm, Re of 125 nm, and Rth of −65 nm.
For Comparative Example 4, a retardation film 9 is produced by the same means as in Example 3 except that the wire bar count at the production of the liquid crystal layer (optical compensation layer 2) is changed to # 2.7. did. The formed liquid crystal layer (optical compensation layer 2) had a thickness of 1 μm, Re of 140 nm, and Rth of −70 nm.

[Comparative Example 5]
<Preparation of resin layer (optical compensation layer 1)>
A resin layer (optical compensation layer 1, film thickness: 45 μm) was obtained in the same manner as in Comparative Example 1 so that the cellulose acylate solution B became a core layer having a film thickness of 100 μm. The optical characteristics were measured, and it was confirmed that Re was 110 nm and Rth was 110 nm.

<Preparation of liquid crystal layer (optical compensation layer 2)>
In the same manner as in the liquid crystal layer (optical compensation layer 2) of Example 5, coating is performed on the cellulose acylate film to form a liquid crystal layer (optical compensation layer 2, film thickness: 2 μm). Produced.
The optical properties of the liquid crystal layer (optical compensation layer 2) in the produced retardation film 10 were measured, and Re was 0 nm and Rth was 160 nm.

[Preparation of polarizing plate]
<Viewing side>
The surface of a cellulose acylate film (TD80UL, manufactured by Fuji Film) was subjected to alkali saponification treatment. It was immersed in a 1.5 N aqueous sodium hydroxide solution at 55 ° C. for 2 minutes, washed in a water bath at room temperature, and neutralized with 0.1 N sulfuric acid at 30 ° C. Again, it was washed in a water bath at room temperature and further dried with hot air at 100 ° C.
Next, a thin film polarizer was produced as follows according to the method described in Japanese Patent No. 4804588. Specifically, first, isophthalic acid copolymerized polyethylene terephthalate copolymerized with 6 mol% of isophthalic acid was prepared as an amorphous ester thermoplastic resin substrate. On this resin base material, a PVA resin layer was formed by coating. After the resin base material and the PVA resin layer are integrally stretched in a two-stage stretching process consisting of air-assisted stretching and boric acid water stretching, the PVA resin layer is dyed with a dichroic dye, A polarizer having a thickness of 3 μm was prepared by peeling off the crystalline ester-based thermoplastic resin substrate.
After the optical compensation layer 1 or 2 described in the following Table 1 is bonded to the surface of one side of the polarizer with the retardation films 1 to 10 described above, the other surface is subjected to TD80UL saponification treatment. A polarizing plate was produced by bonding.
In addition, the polyvinyl alcohol-type adhesive agent aqueous solution was utilized for bonding.
In addition, the lamination is performed by laminating the slow axis of the retardation film to be bonded and the absorption axis of the polarizer so as to be orthogonal to each other in Examples 1, 4 and 5, and Comparative Examples 1, 4 and 5. Examples 2 and 3 and Comparative Examples 3 and 4 were laminated so as to be parallel.
<Backlight side>
A polarizer similar to the viewer-side polarizer was used, and a polarizing plate A was prepared by bonding TD80UL saponified surfaces to both sides of the polarizer.

[Production of liquid crystal display devices]
The following liquid crystal cell 1 or liquid crystal cell 2 was used as the liquid crystal cell.
<Liquid crystal cell 1>
The polarizing plates on both sides were peeled off from a liquid crystal cell manufactured by Apple (iPad) and used as an IPS mode liquid crystal cell. Δn · d = 350 nm and the pretilt was 2.0 °.
<Liquid crystal cell 2>
The polarizing plates on both sides were peeled from a liquid crystal cell manufactured by SHARP (LC-32GH5), and used as a VA mode liquid crystal cell. Δn · d = 300 nm.

A liquid crystal display device was produced using the previously produced polarizing plate and the liquid crystal cell.
Specifically, the polarizing plate prepared above was disposed on the viewing side of the liquid crystal cell, and the polarizer of polarizing plate A was disposed on the liquid crystal cell side on the backlight side. The combinations of liquid crystal cell modes and retardation films are as shown in Table 1 below.

[Evaluation]
Evaluation of the display performance was performed in Examples 1 to 4 and Comparative Examples 1 to 4 (liquid crystal cell: IPS mode) using a backlight of a commercially available liquid crystal display device iPad (manufactured by Apple). No. 5 (liquid crystal cell: VA mode) was evaluated using a backlight of a commercially available liquid crystal display device LC-32GH5 (manufactured by SHARP) so that the produced optical compensation layer was on the viewing side.

<Evaluation of light leakage in an oblique direction during black display>
Each produced liquid crystal display device was displayed in black, and the degree of light leakage from the normal direction of the display surface in the polar angle direction of 60 ° and the azimuth angle direction of 0 to 360 ° was visually evaluated according to the following criteria. The evaluation method was made by comparing a plurality of displays in parallel and comparing them at the same time, and evaluated according to the following criteria. The evaluation results are shown in Table 1 below.
(Evaluation criteria)
A: No light leakage B: Light leakage but no problem in practical use C: There is significant light leakage

<Evaluation of color shift>
The color shift is measured by displaying each produced liquid crystal display device in black, and changing the hue in the direction of the polar angle of 60 ° from the normal direction of the display surface to a commercially available liquid crystal viewing angle and chromaticity characteristic measuring device Ezcom (ELDIM). The maximum change width (Δu′v ′) is shown when the blackness change (in increments of 5 °) at a polar angle of 60 ° is plotted on the u′v ′ plane. The larger the value, the greater the color change, and the evaluation was made in the following three stages A to C. The evaluation results are shown in Table 1 below.
(Evaluation criteria)
A: 0.15 or less B: More than 0.15 and 0.25 or less C: More than 0.25

  As apparent from Table 1 above, when Examples and Comparative Examples having the same numbers are compared, a resin layer containing a polyvinyl alcohol-based resin and having a thickness and Re (550) in a specific range, and a thickness within a predetermined range It was found that by using a retardation film having a liquid crystal layer, the device can be thinned while maintaining the light leakage and color shift display characteristics during black display.

10 retardation film 12 resin layer 14 liquid crystal layer 14a liquid crystal layer (vertical alignment rod-like liquid crystalline compound)
14b Liquid crystal layer (vertically aligned discotic liquid crystalline compound)
14c Liquid crystal layer (horizontal alignment discotic liquid crystalline compound)
20, 30, 40 Liquid crystal display device 22 Viewing side polarizer 24 Liquid crystal cell 26 Backlight side polarizer

Claims (26)

A retardation film having a resin layer and a liquid crystal layer,
The resin layer is a resin layer containing a polyvinyl alcohol-based resin, having a thickness of 3 μm to 20 μm, and Re (550) of 80 nm to 300 nm,
Nz value of the resin layer (however, “Nz = Rth (550) / Re (550) +0.5”) is more than 1.0 and not more than 2.0,
Ri der thickness 5μm or less of the liquid crystal layer,
A retardation film in which the optical characteristics of the liquid crystal layer satisfy the following formulas (1-1) and (1-2) .
Formula (1-1) 0 nm ≦ Re (550) ≦ 10 nm
Formula (1-2) −200 nm ≦ Rth (550) ≦ −100 nm
(However, Re (550) is Table in-plane retardation (nm) at a wavelength of 550nm, Rth (550) a thickness-direction retardation at a wavelength of 550nm is (nm) Table to.) The retardation film according to claim 1, wherein the liquid crystal layer is a film formed by fixing an alignment state of a liquid crystalline compound. Containing rod-like liquid crystal compound in which the liquid crystal layer is vertically aligned, the phase difference film according to claim 1 or 2. The liquid crystal display device which has a visual recognition side polarizer, the phase difference film of any one of Claims 1-3, and a liquid crystal cell in this order. The liquid crystal display device according to claim 4 , wherein the liquid crystal cell is in an IPS mode. 6. The liquid crystal display device according to claim 4 , wherein a total thickness of the viewing side polarizer and the retardation film is 5 μm to 35 μm. The liquid crystal display device according to any one of claims 4 to 6 , wherein an angle formed by an absorption axis of the viewing side polarizer and a slow axis of the retardation film is 85 ° to 95 °. The liquid crystal display device according to any one of claims 4 to 7 , wherein the retardation film is disposed so that the viewing side polarizer and the resin layer constituting the retardation film are adjacent to each other. The angle between the slow axis of the retardation film and the absorption axis of the viewing side polarizer is -5 ° to 5 °, the liquid crystal display device according to any one of claims 4-6. The retardation film, the the liquid crystal cell and the resin layer constituting the retardation film is disposed adjacent the liquid crystal display device according to any one of claims 4-6 and 9. A retardation film having a resin layer and a liquid crystal layer,
The resin layer is a resin layer containing a polyvinyl alcohol-based resin, having a thickness of 3 μm to 20 μm, and Re (550) of 80 nm to 300 nm,
Nz value of the resin layer (however, “Nz = Rth (550) / Re (550) +0.5”) is more than 1.0 and not more than 2.0,
The liquid crystal layer has a thickness of 5 μm or less;
Optical characteristics of the liquid crystal layer satisfies the following formula (2-1) and (2-2), phase difference films.
Formula (2-1) 60 nm ≦ Re (550) ≦ 180 nm
Formula (2-2) −30 nm ≦ Rth (550) ≦ −90 nm
(However, Re (550) represents in-plane retardation (nm) at a wavelength of 550 nm, and Rth (550) represents retardation in the film thickness direction (nm) at a wavelength of 550 nm.)   The retardation film according to claim 11, wherein the liquid crystal layer is a film formed by fixing an alignment state of a liquid crystalline compound. The liquid crystal display which has a visual recognition side polarizer, the phase difference film of Claim 11 or 12 , and a liquid crystal cell in this order. The liquid crystal display device according to claim 13 , wherein the liquid crystal cell is in an IPS mode. The liquid crystal display device according to claim 13 or 14 , wherein a total thickness of the viewing side polarizer and the retardation film is 5 µm to 35 µm. The liquid crystal display device according to any one of claims 13 to 15 , wherein an angle formed between an absorption axis of the viewing side polarizer and a slow axis of the retardation film is -5 ° to 5 °. The liquid crystal display device according to any one of claims 13 to 16 , wherein the retardation film is arranged so that the liquid crystal cell and the resin layer constituting the retardation film are adjacent to each other. The liquid crystal display device according to any one of claims 13 to 15 , wherein an angle formed by an absorption axis of the viewing side polarizer and a slow axis of the retardation film is 85 ° to 95 °. The liquid crystal display according to any one of claims 13 to 15 and 18 , wherein the retardation film is disposed so that the viewing-side polarizer and the resin layer constituting the retardation film are adjacent to each other. apparatus. A retardation film having a resin layer and a liquid crystal layer,
The resin layer is a resin layer containing a polyvinyl alcohol-based resin, having a thickness of 3 μm to 20 μm, and Re (550) of 80 nm to 300 nm,
Nz value of the resin layer (however, “Nz = Rth (550) / Re (550) +0.5”) is more than 1.0 and not more than 2.0,
The liquid crystal layer has a thickness of 5 μm or less;
Optical characteristics of the liquid crystal layer satisfies the following formula (3-1) and (3-2), phase difference films.
Formula (3-1) 0 nm ≦ Re (550) ≦ 10 nm
Formula (3-2) 100 nm ≦ Rth (550) ≦ 200 nm
(However, Re (550) represents in-plane retardation (nm) at a wavelength of 550 nm, and Rth (550) represents retardation in the film thickness direction (nm) at a wavelength of 550 nm.)   The retardation film according to claim 20, wherein the liquid crystal layer is a film formed by fixing an alignment state of a liquid crystalline compound. The liquid crystal display which has a visual recognition side polarizer, the phase difference film of Claim 20 or 21 , and a liquid crystal cell in this order. The liquid crystal display device according to claim 22 , wherein the liquid crystal cell is in a VA mode. The total thickness of the viewing side polarizer and the retardation film is 5Myuemu～35myuemu, liquid crystal display device according to claim 22 or 23. The liquid crystal display device according to any one of claims 22 to 24 , wherein an angle formed between an absorption axis of the viewing side polarizer and a slow axis of the retardation film is 85 ° to 95 °. The liquid crystal display device according to any one of claims 22 to 25 , wherein the retardation film is disposed so that the viewing-side polarizer and the resin layer constituting the retardation film are adjacent to each other.