JP2012181277A - Polarizing plate, polarizing plate set, liquid crystal panel and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarizing plate, a polarizing plate set, a liquid crystal panel and a liquid crystal display device in which an outer resin film is hard to be broken, and the thickness of the whole polarizing plate can be thinned and defects due to moisture moving in and out from an external environment are hard to be generated.SOLUTION: There is provided a polarizing plate 20 in which a first retardation film 23, a first polarizing film 21 and a first outer resin film 25 are laminated in this order, the polarizing plate 20 being used by sticking to a liquid crystal cell 40. The first retardation film 23 made of a biaxial cellulose resin has an in-plane retardation value of 30 to 200 nm and a thickness-direction retardation value of 100 to 350 nm. The first outer resin film 25 made of an acrylic resin composition in which rubber elastomer particles are blended in a transparent acrylic resin, has an internal haze value of 0.5% or less and an external haze value of 5% or less. The first retardation film 23, the first polarizing film 21 and the first outer resin film 25 are disposed so that these films are sequentially positioned from a side close to the liquid crystal cell 40.

Description

  The present invention relates to a polarizing plate, a set of polarizing plates, a liquid crystal panel, and a liquid crystal display device, and more particularly, a polarizing plate in which a retardation film, a polarizing film, and an outer resin film are laminated, a set of polarizing plates, a liquid crystal panel, and a liquid crystal display device About.

  Liquid crystal display devices (LCDs) are used as information display devices such as mobile phones, personal digital assistants, computer monitors, and televisions. In recent years, light-weight and thin liquid crystal display devices that consume less power, are driven at a low voltage, and have become rapidly popularized. With the progress of liquid crystal technology, liquid crystal display devices of various modes have been proposed, and problems peculiar to liquid crystal display devices such as response speed, contrast, and narrow viewing angle are being solved. However, it has been pointed out that the viewing angle of a liquid crystal display device is still narrower than that of a cathode ray tube (CRT), and various attempts have been made to expand the viewing angle.

  In general, a liquid crystal display device has a configuration in which polarizing plates are bonded to both sides of a liquid crystal cell. As a polarizing plate, what has the structure on which the outer side resin film, the polarizing film, and the phase difference film were laminated | stacked in order from the distant side of a liquid crystal cell is known. As the outer resin film, a protective film having a role of protecting the surface of the polarizing film is used. On the other hand, the retardation film has an optical compensation function for compensating for birefringence and the like of the liquid crystal cell itself.

  One type of liquid crystal cell is a vertical alignment (VA) mode in which rod-like liquid crystal molecules having positive or negative dielectric anisotropy are aligned perpendicular to a substrate. When the liquid crystal cell in the vertical alignment mode is not driven, the liquid crystal molecules of the liquid crystal cell are aligned perpendicularly to the substrate, so that light passes through the liquid crystal layer without being changed in polarization. For this reason, by arranging the linearly polarizing plates so that the absorption axes are orthogonal to each other above and below the liquid crystal panel, almost complete black display can be obtained when viewed from the front, and a high contrast ratio can be obtained. .

  However, in the VA mode liquid crystal display device having only the polarizing plate in the liquid crystal cell, the axial angle of the arranged polarizing plate is deviated from 90 ° when viewed from an oblique direction, and the rod shape in the cell Light leakage occurs due to the birefringence of the liquid crystal molecules. As a result, there is a problem in that the contrast ratio varies significantly and the color tone changes depending on the viewing angle. Note that the contrast ratio and the color change when such a liquid crystal display device is viewed obliquely are referred to as “viewing angle characteristics”.

  In order to eliminate this defect in viewing angle characteristics, it is necessary to dispose an optical compensation film between the liquid crystal cell and the linear polarizing plate. Conventionally, a biaxial retardation film is provided as an optical compensation film between the liquid crystal cell and the upper and lower polarizing films, respectively, or a uniaxial retardation film and a complete biaxial retardation film. The specification of arranging each one above and below the liquid crystal cell, the specification of arranging both on one side of the liquid crystal cell, and the like have been adopted.

  As a retardation film used in the VA mode, a norbornene resin (for example, see Patent Document 1) and a cellulose resin film (for example, see Patent Document 2) are known. In these documents, a film made of norbornene resin (cycloolefin resin) or a cellulose derivative is produced by biaxial stretching, and the refractive index in the slow axis direction in the film plane is nx, and the slow axis in the film plane. A retardation film satisfying nx> ny> nz, where ny is the refractive index in the direction orthogonal to the direction and nz is the refractive index in the thickness direction, is used as the retardation film for VA mode compensation. As a result, when black display is performed when the VA cell is not driven, light leakage during tilt observation can be significantly suppressed over a wide range to maintain low luminance, and a high contrast ratio and wide viewing angle can be achieved. It becomes.

  In addition, a technique for forming the outer resin film with a resin other than cellulose acetate has been proposed. As such a resin other than cellulose acetate, there is a technique using a relatively inexpensive acrylic resin. As an acrylic resin, a protective film made of a (meth) acrylic resin containing a lactone ring is known (for example, see Patent Document 3). By providing a protective film made of such an acrylic resin, it is possible to provide a polarizing plate that is inexpensive and excellent in durability and display uniformity.

  Furthermore, a polarizing plate protective film obtained by uniaxially or biaxially stretching an acrylic resin within a stretch ratio of 50 to 200% is known (for example, see Patent Document 4). By using such a stretched acrylic resin, an optical film having excellent mechanical strength and heat shrinkability can be obtained.

  On the other hand, the polarizing plate generally has a structure in which the outer resin film / adhesive / polarizer / adhesive / inner resin film (or retardation film) are laminated in this order. Among them, as described in Patent Document 1, a norbornene-based resin may be used as a retardation film. However, since the norbornene-based resin has a lower moisture permeability than the cellulose-based resin, in the retardation film state, moisture easily stays in the interior with respect to moisture that enters and exits from the external environment. There is a problem that defects such as point defects are likely to occur due to moisture. This problem is particularly noticeable when the outer resin film of the polarizing plate is a film made of a resin having a moisture permeability lower than that of the cellulose resin (for example, cycloolefin resin, acrylic resin, polyester resin, polyolefin resin, etc.). Concerned.

JP-A-8-43812 (Claim 2, paragraph 0004) WO2007 / 018267 (Claim 1, paragraph 0045) JP 2009-122663 A (Claim 1) JP 2008-216586 A (Claim 1)

  The above-described outer resin film made of the conventional acrylic resin has a problem that it is inferior in flexibility and easily broken. Therefore, research is being carried out to increase the flexibility of the outer resin film made of acrylic resin and make it difficult to break.

  An object of the present invention is to provide a polarizing plate, a set of polarizing plates, a liquid crystal panel, and a liquid crystal display device, in which an outer resin film is hardly broken and the entire thickness can be reduced.

  Furthermore, the object of the present invention is a combination of an outer resin film and an inner resin film, which appropriately absorbs / discharges moisture that comes in and out from the external environment, and a set of polarizing plates and polarizing plates that are less prone to moisture-induced defects, A liquid crystal panel and a liquid crystal display device are provided.

  According to the polarizing plate of the present invention, the above-described problem is that the first retardation film, the first polarizing film, and the first outer resin film are laminated in this order and are used by being bonded to a liquid crystal cell. The first retardation film is a biaxial cellulose-based resin having an in-plane retardation value in the range of 30 to 200 nm and a thickness direction retardation value in the range of 100 to 350 nm. The first outer resin film is made of an acrylic resin composition in which 25 to 45% by weight of rubber elastic body particles having a number average particle diameter of 10 to 300 nm are blended in a transparent acrylic resin, and has an internal haze value. Is 0.5% or less and the external haze value is 5% or less, and the first retardation film, the first polarizing film, and the first outer resin film are positioned in order from the side closer to the liquid crystal cell. By being placed in It is determined.

  In this case, the first polarizing film and the first retardation film, and the first polarizing film and the first outer resin film are each composed of a resin composition containing an epoxy compound that is cured by active energy rays. It is preferable that they are bonded by an adhesive.

  The rubber elastic body particles preferably contain an acrylic elastic polymer.

  Moreover, the said subject is for the liquid crystal display which consists of the 1st polarizing plate arrange | positioned at the visual recognition side of a liquid crystal cell, and the 2nd polarizing plate arrange | positioned at a back side according to the set of the polarizing plate of this invention. A set of polarizing plates, wherein one of the first polarizing plate and the second polarizing plate is the polarizing plate according to any one of the above, and the first polarizing plate and the second polarizing plate. The other polarizing plate is formed by laminating a second retardation film, a second polarizing film, and a second outer resin film in this order, and in order from the side closer to the liquid crystal cell, The retardation film, the second polarizing film, and the second outer resin film are disposed so that the second retardation film has an in-plane retardation value in the range of 30 to 200 nm at a wavelength of 590 nm. Thickness direction retardation value at 590 nm is 100 to 350 In the range of m, it is solved by comprising a biaxial cellulose resin film.

  Further, according to the liquid crystal panel of the present invention, the above-mentioned problem is composed of a liquid crystal cell and a pair of polarizing plates disposed on both sides thereof, and the pair of polarizing plates is the set of polarizing plates described above. The first outer resin film, the first polarizing film, the first retardation film, the liquid crystal cell, the second retardation film, the second polarizing film, and the second outer resin film are laminated in this order. Is solved.

  In addition, according to the liquid crystal display device of the present invention, the above problem includes a backlight, a light diffusion plate, and the liquid crystal panel described above, and the backlight, the light diffusion plate, the second polarizing plate, This is solved by arranging the liquid crystal cell and the first polarizing plate in this order.

  Furthermore, the liquid crystal cell is preferably a VA mode liquid crystal cell.

  According to the set of the polarizing plate and the polarizing plate of the present invention, since the elastic rubber particles are blended in the acrylic resin constituting the outer resin film, the outer resin film has excellent flexibility, is thin, and breaks. It is difficult to do. In addition, since the inner resin film is composed of a biaxial cellulose-based resin film that can be thinned, the entire polarizing plate can be made thinner than a conventional cycloolefin-based resin film. Furthermore, since the cellulose resin film has higher moisture permeability than a cycloolefin resin or the like, it is possible to appropriately absorb / discharge moisture from the external environment. For this reason, there is also an advantage that moisture hardly accumulates inside the polarizing plate, and problems caused by moisture hardly occur.

  In addition, according to the liquid crystal panel and the liquid crystal display device of the present invention, since the thin polarizing plate that is difficult to break is used, it is possible to provide a device having durability and wear resistance and a thin film. It becomes. In addition, it is possible to provide a device that is less prone to problems due to moisture in the external environment.

It is a cross-sectional schematic diagram of the set of a polarizing plate and a polarizing plate. It is a cross-sectional schematic diagram of the liquid crystal panel and liquid crystal display device using the set of polarizing plates.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In addition, this invention is not limited by the member, arrangement | positioning, etc. which are demonstrated below, These members etc. can be suitably changed in accordance with the meaning of this invention.

(First embodiment)
Hereinafter, a polarizing plate, a set of polarizing plates, a liquid crystal panel and a liquid crystal display device including the same according to the first embodiment of the present invention will be described.

  <Polarizing plate and polarizing plate set>

  Hereinafter, a polarizing plate, a set of polarizing plates, a liquid crystal panel, and a liquid crystal display device according to an embodiment of the present invention will be described. FIG. 1: has shown the cross-sectional schematic diagram of the set of the polarizing plate and polarizing plate which concerns on one Embodiment of this invention. As shown in this figure, the polarizing plate 20 has a layer structure in which a retardation film 23, a polarizing film 21, and an outer resin film 25 are laminated in this order. The set of polarizing plates includes a polarizing plate 20 that is a first polarizing plate and a polarizing plate 30 that is a second polarizing plate.

  As shown in FIG. 2, these polarizing plates 20 and 30 are used as components of the liquid crystal panel 2 and the liquid crystal display device 1. The liquid crystal panel 2 can be manufactured by laminating the polarizing plate 20 and the polarizing plate 30 on both surfaces of the liquid crystal cell 40. In the present embodiment, the polarizing plate 20 and the polarizing plate 30 constitute a back side polarizing plate and a viewing side polarizing plate of the liquid crystal panel 2, respectively. Here, “back-side polarizing plate” means a polarizing plate located on the backlight 10 side when the liquid crystal panel 2 is mounted on the liquid crystal display device 1, and “viewing-side polarizing plate” means the liquid crystal panel 2. Means a polarizing plate located on the viewing side (opposite side of the backlight 10) when mounted on the liquid crystal display device 1. Hereinafter, the polarizing plate 20 will be described in detail.

(A) Polarizing plate 20 (first polarizing plate)
The polarizing plate 20 is a polarizing plate used as a back side polarizing plate (polarizing plate 20) of the liquid crystal panel 2. The polarizing plate 20 corresponds to the first polarizing plate of the present invention. As shown in FIG. 1, the polarizing plate 20 has a layer structure in which an outer resin film 25, a polarizing film 21, a retardation film 23, and an adhesive layer 27 are laminated in this order. Hereinafter, each layer constituting the polarizing plate 20 will be described.

(1) Polarizing film 21 (first polarizing film)
The polarizing film 21 is a film having a function of converting natural light into linearly polarized light. The polarizing film 21 corresponds to the first polarizing film of the present invention. As the polarizing film 21, a film obtained by adsorbing and orienting a dichroic dye on a uniaxially stretched polyvinyl alcohol resin film can be used. As the polyvinyl alcohol resin, a saponified polyvinyl acetate resin can be used. As the polyvinyl acetate resin, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate, polyvinyl acetate and Examples thereof include copolymers with other copolymerizable monomers. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

  The saponification degree of the polyvinyl alcohol resin is usually about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can also be used. The degree of polymerization of the polyvinyl alcohol resin is usually about 1,000 to 10,000, preferably about 1,500 to 5,000.

  A film obtained by forming such a polyvinyl alcohol resin is used as a raw film of the polarizing film 21. The method for forming a polyvinyl alcohol-based resin is not particularly limited, and can be formed by a known method. Although the thickness of a polyvinyl alcohol-type raw film is not specifically limited, For example, it is about 5-150 micrometers.

  The polarizing film 21 usually has a step of uniaxially stretching such a polyvinyl alcohol resin film, a step of adsorbing a dichroic dye by dyeing the polyvinyl alcohol resin film with a dichroic dye, and a dichroic dye It is manufactured through a step of treating the adsorbed polyvinyl alcohol-based resin film with a boric acid aqueous solution and a step of washing with water after the treatment with the boric acid aqueous solution.

  Uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before dyeing with the dichroic dye, simultaneously with dyeing, or after dyeing. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Moreover, uniaxial stretching can also be performed in several steps. For uniaxial stretching, a method of stretching uniaxially between rolls having different peripheral speeds, a method of stretching uniaxially using a hot roll, or the like can be adopted. Further, the uniaxial stretching may be dry stretching in which stretching is performed in the air, or may be wet stretching in which stretching is performed in a state where a polyvinyl alcohol-based resin film is swollen using a solvent such as water. The draw ratio is usually about 3 to 8 times.

  The polyvinyl alcohol resin film can be dyed with a dichroic dye by, for example, a method of immersing the polyvinyl alcohol resin film in an aqueous solution containing the dichroic dye. Specifically, iodine or a dichroic dye is used as the dichroic dye. In addition, it is preferable to perform the process which a polyvinyl alcohol-type resin film swells by immersing in water before a dyeing process.

  When iodine is used as the dichroic dye, a method of dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide is usually employed. The content of iodine in this aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water, and the content of potassium iodide is usually about 0.5 to 20 parts by weight per 100 parts by weight of water. It is. The temperature of the aqueous solution used for dyeing is usually about 20 to 40 ° C. Moreover, the immersion time (dyeing time) in this aqueous solution is usually about 20 to 1,800 seconds.

On the other hand, when a dichroic dye is used as the dichroic dye, a method of immersing and dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye is usually employed. The content of the dichroic dye in this aqueous solution is usually about 1 × 10 ⁻⁴ to 10 parts by weight, preferably about 1 × 10 ⁻³ to 1 part by weight per 100 parts by weight of water. This aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing assistant. The temperature of the aqueous dichroic dye solution used for dyeing is usually about 20 to 80 ° C. Moreover, the immersion time (dyeing time) in this aqueous solution is usually about 10 to 1,800 seconds.

  The boric acid treatment after dyeing with a dichroic dye can be performed by immersing the dyed polyvinyl alcohol-based resin film in a boric acid-containing aqueous solution. The boric acid content in the boric acid-containing aqueous solution is usually about 2 to 15 parts by weight, preferably about 5 to 12 parts by weight per 100 parts by weight of water. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide. The content of potassium iodide in the boric acid-containing aqueous solution is usually about 0.1 to 15 parts by weight, preferably about 5 to 12 parts by weight per 100 parts by weight of water. The immersion time in the boric acid-containing aqueous solution is usually about 60 to 1,200 seconds, preferably about 150 to 600 seconds, and more preferably about 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 ° C. or higher, preferably 50 to 85 ° C., more preferably 60 to 80 ° C.

  The polyvinyl alcohol resin film after the boric acid treatment is usually washed with water. The water washing treatment can be performed, for example, by immersing a boric acid-treated polyvinyl alcohol resin film in water. The temperature of water in the water washing treatment is usually about 5 to 40 ° C., and the immersion time is usually about 1 to 120 seconds.

  After washing with water, a drying process is performed to obtain the polarizing film 21. The drying process can be performed using a hot air dryer or a far infrared heater. The temperature of a drying process is about 30-100 degreeC normally, Preferably it is 50-80 degreeC. The drying time is usually about 60 to 600 seconds, preferably 120 to 600 seconds.

  In this way, the polyvinyl alcohol-based resin film is subjected to uniaxial stretching, dyeing with a dichroic dye, and boric acid treatment, and the polarizing film 21 is obtained. The thickness of the polarizing film 21 can be about 2-40 micrometers, for example.

(2) Retardation film 23 (first retardation film)
The phase difference film 23 is a phase difference film disposed between the polarizing film 21 and the pressure-sensitive adhesive layer 27. The retardation film 23 has an optical compensation function that widens the viewing angle when bonded to the liquid crystal cell 40. The retardation film 23 corresponds to the first retardation film of the present invention.

The retardation film 23 is a retardation film made of a biaxial cellulose-based resin having an in-plane retardation value R ₀ in the range of 30 to 200 nm and a thickness direction retardation value R _th in the range of 100 to 350 nm. is there. The in-plane retardation value R ₀ and the thickness direction retardation value R _th here are values at a wavelength of 590 nm, and so on.

  The retardation film 23 preferably has a Gurley method bending resistance measured in accordance with JIS L 1096 of 350 mgf or less, more preferably 200 mgf or less, and even more preferably 150 mgf or less. Thus, since the rigidity of the obtained polarizing plate 20 is reduced by using the retardation film 23 having a low bending resistance, handling properties when bonding to the liquid crystal cell 40 can be improved.

  With the above cellulose-based resin, some or all of the hydrogen atoms in the hydroxyl group of cellulose obtained from raw material cellulose such as cotton linter and wood pulp (broadwood pulp, conifer pulp) are substituted with acetyl, propionyl and / or butyryl groups. The cellulose organic acid ester or cellulose mixed organic acid ester. For example, cellulose acetate, propionate, butyrate, and mixed esters thereof can be used. Among these, triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, cellulose acetate butyrate, or the like is preferably used. Commercially available films using such a cellulose-based resin include the Konica Minolta Opto Co., Ltd. Konica Minolta Tack Film Series and the Fuji Film Corporation Fuji Tac Series.

  As the cellulose resin constituting the retardation film 23, the above-described cellulose resin may be used alone, or two or more kinds may be used in combination. These cellulose resins can be used after any appropriate polymer modification. Examples of the polymer modification include modification such as copolymerization, cross-linking, molecular terminal modification, stereoregularity control, and mixing including a case involving reactions between different polymers.

  A cellulose-based resin film suitable as the retardation film 23 is obtained by stretching an unstretched film made of the above-described cellulose-based resin to develop a retardation, thereby obtaining a retardation film 23. As described above, a retardation film made of a so-called biaxial cellulose resin is generally prepared by stretching an unstretched film in a biaxial direction. In particular, those in which biaxial birefringence is expressed by successive biaxial stretching are preferred. The stretching ratio at this time is approximately 1.1 to 10 times in the direction in which the optical axis is expressed (the direction in which the stretching ratio is large and the slow axis) among the longitudinal direction and the transverse direction, and is orthogonal to that. What is necessary is just to select suitably from the range of about 1.1-7 times by the direction (direction where a draw ratio is small, and becomes a fast axis) according to the required phase difference value. The optical axis may be developed in the lateral direction of the film, or the optical axis may be developed in the longitudinal direction.

  The thickness of the retardation film 23 is preferably as thin as possible in the range where the polarizing plate and the liquid crystal display device using the retardation film 23 can be reduced in weight and thickness. Specifically, it is in the range of 5 to 100 μm, preferably in the range of 10 to 70 μm, and more preferably in the range of 20 to 50 μm. In particular, the retardation film 23 made of a cellulose resin is preferable because it can be made thinner than a retardation film made of a cycloolefin resin.

Next, the retardation value of the retardation film 23 will be described. The refractive index of in-plane slow axis direction n _x of the _film, the refractive index n _y in-plane fast axis direction (direction orthogonal with the slow axis and the _plane), the refractive index in the thickness direction n _z, thickness Where d is the in-plane retardation value R ₀ and the thickness direction retardation value R _th are defined by the following equations (I) and (II), respectively.

_{R 0 = (n x -n y} ) × d (I)
_Rth = [( _nx + _ny ) / 2- _nz ] * d (II).
Furthermore, when the liquid crystal cell 40 is in the VA mode, the retardation film 23 preferably satisfies the relationship of the following formula (III) with respect to its refractive index.
_nx > _ny > _nz (III).

In the present invention, the retardation film 23 having an in-plane retardation value R ₀ in the range of 30 to 200 nm and a thickness direction retardation value R _th in the range of 100 to 350 nm is used. The phase difference value may be appropriately selected according to the characteristics required for the applied liquid crystal display device 1. The in-plane retardation value R ₀ is preferably 100 nm or less, and the thickness direction retardation value R _th is preferably 80 nm or more and 200 nm or less.

The accuracy of the in-plane retardation value R ₀ is within the center value ± 7 nm, preferably within the center value ± 5 nm, and the accuracy of the thickness direction retardation value R _th is within the center value ± 15 nm, preferably the center value ± 10 nm. Is within. If the accuracy of these values exceeds the above range, the visual characteristics of the applied liquid crystal display device 1 tend to deteriorate.

  The slow axis angle in the film plane of the retardation film 23 is substantially 0 ° or 90 ° with respect to the absorption axis of the polarizing film. If the slow axis deviates from this angle, light leakage occurs when the polarizing plate is set in a crossed Nicol state, and when applied to the liquid crystal display device 1, visual characteristics such as front contrast tend to be greatly reduced. is there. The accuracy of the slow axis is preferably within the center value ± 0.7 °, and more preferably within the center value ± 0.5 °. Here, the light leakage means that when the axial accuracy of the polarizing film 21 with respect to the biaxial retardation film 23 or the axial accuracy of the polarizing plate 20 with respect to the liquid crystal cell 40 is poor, the liquid crystal display device 1 starts from the entire display area when displaying black. A phenomenon in which light leaks. As described above, the shift of the slow axis in the retardation film 23 is reduced, and therefore the shift of the angle between the slow axis and the absorption axis of the polarizing film 21 is also reduced. By increasing the axial accuracy of the polarizing plates (polarizing plate 20 and polarizing plate 30) bonded to the front and back surfaces of the cell 40, and reducing the deviation from 90 ° of the angle formed by the absorption axes of both polarizing plates, light leakage Can be reduced.

  In adhering the retardation film 23 to the polarizing film 21, the optimum axial relationship between them may be selected in consideration of the viewing angle characteristics and color change characteristics of the target liquid crystal display device 1. In large liquid crystal television applications where the front contrast is important, the slow axis of the retardation film 23 and the absorption axis of the polarizing film 21 are often arranged so as to have a substantially parallel or substantially orthogonal relationship. Here, “substantially parallel or substantially orthogonal” includes not only the case of being completely parallel or orthogonal but also the case of deviation from the parallel or orthogonal relationship within a range of about ± 10 °. The angle deviation is preferably within ± 5 °, more preferably within ± 2 °. The slow axis of the retardation film 23 and the absorption axis of the polarizing film are preferably in a completely parallel or orthogonal relationship.

(3) Outer resin film 25 (first outer resin film)
The outer resin film 25 is a member having functions such as wear prevention and reinforcement of the surface of the polarizing film 21 and is made of an acrylic resin. The outer resin film 25 corresponds to the first outer resin film of the present invention.

  The acrylic resin constituting the outer resin film 25 is blended with 25 to 45% by weight of rubber elastic particles having a number average particle diameter of 10 to 300 nm in order to improve flexibility and handleability. The outer resin film 25 has high transparency and optical uniformity. Specifically, the internal haze value of the outer resin film 25 is 0.5% or less and the external haze value is 5% or less.

[Acrylic resin]
The acrylic resin is made of a polymer mainly composed of alkyl methacrylate. The monomer composition of the alkyl methacrylate is preferably 70% by weight or more, more preferably 80% by weight or more, and still more preferably 90% by weight or more, based on the total 100% by weight of all monomers. And alkyl methacrylate is 99% by weight or less. The acrylic resin may be a homopolymer of alkyl methacrylate, or a copolymer of 50% by weight or more of alkyl methacrylate and 50% by weight or less of a monomer other than alkyl methacrylate. Also good. As the alkyl methacrylate, those having 1 to 4 carbon atoms of the alkyl group are usually used, and among them, methyl methacrylate is preferably used.

  The monomer other than alkyl methacrylate may be a monofunctional monomer having one polymerizable carbon-carbon double bond in the molecule, or two or more polymerizable carbons in the molecule. -A polyfunctional monomer having a carbon double bond may be used. In particular, monofunctional monomers are preferably used. Examples thereof include alkyl acrylates such as methyl acrylate and ethyl acrylate, styrene monomers such as styrene and alkyl styrene, acrylonitrile and methacrylonitrile. Such unsaturated nitriles. When using alkyl acrylate as a copolymerization component, the carbon number is 1-8 normally.

  The acrylic resin preferably does not have a glutarimide derivative, a glutaric anhydride derivative, a lactone ring structure, or the like. These acrylic resins may be difficult to obtain sufficient mechanical strength and heat-and-moisture resistance as the outer resin film 25.

[Rubber elastic particles]
The rubber elastic body particles contained in the outer resin film 25 are particles containing a rubber elastic body, and may be particles composed only of a rubber elastic body, or particles having a multilayer structure having a rubber elastic body layer. There may be. Examples of rubber elastic bodies include olefin-based elastic polymers, diene-based elastic polymers, styrene-diene-based elastic copolymers, and acrylic-based elastic polymers. Among them, an acrylic elastic polymer is preferably used from the viewpoint of the surface hardness, light resistance, and transparency of the outer resin film 25.

  The acrylic elastic polymer is preferably a polymer mainly composed of alkyl acrylate, and may be a homopolymer of alkyl acrylate, or may be a single polymer other than alkyl acrylate of 50% by weight or more and alkyl acrylate. A copolymer with 50% by weight or less of the monomer may be used. As the alkyl acrylate, those having 4 to 8 carbon atoms in the alkyl group are usually used. Examples of monomers other than alkyl acrylate include alkyl methacrylates such as methyl methacrylate and ethyl methacrylate, styrene monomers such as styrene and alkyl styrene, acrylonitrile and methacrylonitrile. Monofunctional monomers such as unsaturated nitriles, alkenyl esters of unsaturated carboxylic acids such as allyl (meth) acrylate and methallyl (meth) acrylate, dialkenyl esters of dibasic acids such as diallyl maleate, And polyfunctional monomers such as unsaturated carboxylic acid diesters of glycols such as alkylene glycol di (meth) acrylate.

  The rubber elastic particle containing the acrylic elastic polymer is preferably a multi-layered particle having an acrylic elastic polymer layer, and a polymer mainly composed of alkyl methacrylate outside the acrylic elastic polymer. It may be a two-layer structure having the above-mentioned layer, or a three-layer structure having a polymer layer mainly composed of alkyl methacrylate inside the acrylic elastic polymer. In addition, the example of the monomer composition of the polymer mainly composed of alkyl methacrylate constituting the layer formed on the outside or inside of the acrylic elastic polymer is the alkyl methacrylate mentioned above as an example of the acrylic resin. It is the same as that of the example of the monomer composition of the polymer which has mainly. Such acrylic rubber elastic particles having a multilayer structure can be produced, for example, by the method described in Japanese Patent Publication No. 55-27576.

  As the rubber elastic particles, those having a number average particle diameter of 10 to 300 nm of rubber elastic bodies contained therein are used. Thereby, when the outer side resin film 25 is laminated | stacked on the polarizing film 21 using an adhesive agent, the outer side resin film 25 can be made hard to peel from an adhesive bond layer. The number average particle diameter of the rubber elastic body is preferably 50 nm or more and 250 nm or less.

  In the case of rubber elastic particles in which the outermost layer is a polymer mainly composed of methyl methacrylate and the acrylic elastic polymer is encapsulated therein, the rubber elastic particles are mixed with the base acrylic resin. Since the outermost layer of the resin is mixed with the base acrylic resin, the rubber elastic particles are excluded from the outermost layer when the acrylic elastic polymer is dyed with ruthenium oxide in the cross section and observed with an electron microscope. It is observed as particles in a wet state. Specifically, in the case of using rubber elastic particles having a two-layer structure in which the inner layer is an acrylic elastic polymer and the outer layer is a polymer mainly composed of methyl methacrylate, the inner layer is an acrylic elastic polymer. The portion is dyed and observed as particles having a single layer structure. Further, the rubber elastic particles having a three-layer structure in which the innermost layer is a polymer mainly composed of methyl methacrylate, the intermediate layer is an acrylic elastic polymer, and the outermost layer is a polymer mainly composed of methyl methacrylate. When is used, the center part of the innermost layer particle is not dyed, and only the acrylic elastic polymer part of the intermediate layer is dyed and observed as a two-layered particle. In this specification, the number average particle diameter of the rubber elastic particles is, as described above, when the rubber elastic particles are mixed with the base resin and the cross section is dyed with ruthenium oxide. It is the number average value of the diameter of the part to be done.

  In the acrylic resin composition forming the outer resin film 25, 25 to 45% by weight of rubber elastic body particles having a number average particle diameter of 10 to 300 nm is blended in a transparent acrylic resin.

  The acrylic resin composition is produced, for example, by obtaining rubber elastic particles and then polymerizing a monomer as a raw material for the acrylic resin in the presence thereof to produce a base acrylic resin. Alternatively, the rubber elastic particles and the acrylic resin may be obtained and then mixed by melt kneading or the like.

  For the acrylic resin composition, if necessary, colorants such as pigments and dyes, fluorescent brighteners, dispersants, heat stabilizers, light stabilizers, infrared absorbers, ultraviolet absorbers, antistatic agents. Further, a compounding agent such as an antioxidant, a lubricant or a solvent may be contained.

  The ultraviolet absorber is added to improve durability by absorbing ultraviolet rays of 400 nm or less. As the ultraviolet absorber, known ones such as a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, and an acrylonitrile ultraviolet absorber can be used. Among them, 2,2'-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol), 2- (2'-hydroxy-3 ' -Tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2,4-di-tert-butyl-6- (5-chlorobenzotriazol-2-yl) phenol, 2,2'-dihydroxy- 4,4′-dimethoxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone and the like are preferably used. Among these, 2,2′-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol) is particularly preferable. The concentration of the ultraviolet absorber can be selected in such a range that the transmittance of the outer resin film 25 at a wavelength of 370 nm or less is preferably 10% or less, more preferably 5% or less, and further preferably 2% or less. Examples of the method of containing the ultraviolet absorber include a method of previously blending the ultraviolet absorber into the acrylic resin; a method of supplying it directly at the time of melt extrusion molding, and any method may be employed.

  Infrared absorbers include nitroso compounds, metal complexes thereof, cyanine compounds, squarylium compounds, thiol nickel complex compounds, phthalocyanine compounds, naphthalocyanine compounds, triallylmethane compounds, imonium compounds, diimonium compounds, Infrared absorption of naphthoquinone compounds, anthraquinone compounds, amino compounds, aminium salt compounds, carbon black, indium tin oxide, antimony tin oxide, metal oxides belonging to Group 4A, 5A or 6A, carbides, borides, etc. An agent etc. can be mentioned. These infrared absorbers are preferably selected so as to be able to absorb the entire infrared ray (light having a wavelength in the range of about 800 nm to 1100 nm), and two or more types may be used in combination. The amount of the infrared absorber can be appropriately adjusted so that, for example, the light transmittance of the outer resin film 25 at a wavelength of 800 nm or more is 10% or less.

  The glass transition temperature Tg of the acrylic resin composition is preferably in the range of 80 to 120 ° C. Further, the acrylic resin composition has a high surface hardness when formed into a film, specifically, a pencil hardness (with a load of 500 g, conforming to JIS K5600-5-4) of B or more. preferable.

  The acrylic resin composition preferably has a flexural modulus (JIS K7171) of 1500 MPa or less from the viewpoint of flexibility of the outer resin film 25. The flexural modulus is more preferably 1300 MPa or less, and still more preferably 1200 MPa or less. This flexural modulus varies depending on the type and amount of acrylic resin and rubber elastic particles in the acrylic resin composition. For example, as the content of rubber elastic particles increases, the flexural modulus generally decreases. Become. In addition, the use of a copolymer of an alkyl methacrylate and an alkyl acrylate as an acrylic resin generally has a lower flexural modulus than using an alkyl methacrylate homopolymer.

  In addition, the elastic elastic polymer particles having the two-layer structure are generally used as the elastic rubber particles, rather than the acrylic elastic polymer particles having the two-layer structure. In general, the flexural modulus is smaller when the acrylic elastic polymer particles having a layer structure are used. Further, in the rubber elastic body particles, as the average particle diameter of the rubber elastic body is smaller or the amount of the rubber elastic body is larger, the bending elastic modulus is generally smaller. Therefore, it is preferable to adjust the kind and amount of the acrylic resin and the rubber elastic body particles within the predetermined range so that the flexural modulus is 1500 MPa or less.

  When the outer resin film 25 has a multilayer structure, the layer that can exist other than the layer of the acrylic resin composition is not particularly limited in its composition. For example, an acrylic resin containing no rubber elastic body particles or a composition thereof It may be a layer of a product, or may be a layer made of an acrylic resin composition in which the content of rubber elastic particles and the average particle size of the rubber elastic material in the rubber elastic particles are outside the above-mentioned limits. .

  Typically, it has a two-layer or three-layer structure, for example, a two-layer structure composed of a layer of the above-mentioned acrylic resin composition / an acrylic resin not containing rubber elastic particles or a layer of the composition. Alternatively, it may be a three-layer structure composed of the acrylic resin composition layer / the acrylic resin not containing the rubber elastic particles or the composition layer / the acrylic resin composition layer. The outer side resin film 25 having a multi-layer configuration may be a surface of the acrylic resin composition layer used as a bonding surface with the polarizing film 21.

  When the outer resin film 25 has a multilayer structure, the contents of the rubber elastic particles and the layers of the compounding agent may be different from each other. For example, a layer containing an ultraviolet absorber and / or an infrared absorber and a layer not containing an ultraviolet absorber and / or an infrared absorber may be laminated with this layer interposed therebetween. In addition, the content of the ultraviolet absorber in the acrylic resin composition layer is higher than the content of the ultraviolet absorber in the acrylic resin or the composition layer containing no rubber elastic particles. Specifically, the former is preferably 0.5 to 10% by weight, more preferably 1 to 5% by weight, and the latter is preferably 0 to 1% by weight, more preferably 0 to 0.5% by weight. Thus, ultraviolet rays can be efficiently blocked without deteriorating the color tone of the polarizing plate, and a decrease in the degree of polarization during long-term use can be prevented.

  The outer resin film 25 of the present invention is characterized by comprising a non-oriented acrylic resin film that is not stretched. By not performing the stretching treatment in this way, the film thickness is increased, so that the handling property of the outer resin film 25 is improved and the wear resistance and the like are excellent. Such an outer resin film 25 can be obtained from an unstretched film (raw film) obtained by forming the acrylic resin composition.

  The acrylic resin is formed into an unstretched film by any method. This unstretched film is preferably transparent and substantially free of in-plane retardation. Examples of the film forming method include an extrusion method in which a molten resin is extruded to form a film, and a solvent cast method in which a solvent dissolved in an organic solvent is cast on a flat plate and then the solvent is removed to form a film. Etc. can be adopted.

  As a specific example of the extrusion molding method, for example, there is a method of forming a film in a state where an acrylic resin composition is sandwiched between two metal rolls. In this case, the metal roll is preferably a mirror roll. Thereby, the unstretched film excellent in surface smoothness can be obtained. In addition, when the thing of a multilayer structure is obtained as the outer side resin film 25, the said acrylic resin composition should just be formed into a film after multilayer extrusion with another acrylic resin composition. The thickness of the unstretched film thus obtained is preferably 5 to 200 μm, more preferably 10 μm to 85 μm.

  Next, the haze value of the outer resin film 25 will be described. The haze value is the ratio of the diffuse light transmittance to the total light transmittance when the film is irradiated with visible light. It is recognized that the smaller the haze value is, the better the film is. Moreover, an internal haze value shows the value which deducted the haze value (external haze value) resulting from the surface shape of a film from the haze value of a film.

  As described above, the haze value of the outer resin film 25 is preferably 0.5% or less, and preferably 5% or less, as described above. When the internal haze value exceeds 0.5% and the external haze value exceeds 5%, the light transmitted through the film is scattered, and the display characteristics may deteriorate when the liquid crystal display device 1 is bonded.

The retardation value of the outer resin film 25 is not particularly limited, but preferably has substantially no retardation value for the use of the polarizing plate. Specifically, the in-plane retardation value R ₀ is preferably 10 nm or less, and the absolute value of the thickness direction retardation value R _th is preferably 10 nm or less.

(4) Adhesive layer 27 (first adhesive layer)
The pressure-sensitive adhesive layer 27 is a layer having adhesiveness, and is used for bonding the polarizing plate 20 to the liquid crystal cell 40. The pressure-sensitive adhesive layer 27 corresponds to the first pressure-sensitive adhesive layer of the present invention. Examples of the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer 27 include those having an acrylic polymer, silicone-based polymer, polyester, polyurethane, polyether or the like as a base polymer. Among them, acrylic pressure-sensitive adhesives based on acrylic polymers are excellent in optical transparency, maintain appropriate wettability and cohesive strength, and are also excellent in weather resistance and heat resistance. It is preferably used because it does not easily cause separation problems such as floating and peeling even under conditions.

  In the acrylic base polymer constituting the acrylic pressure-sensitive adhesive, an acrylic acid alkyl ester having an ester group having an alkyl group having 20 or less carbon atoms such as a methyl group, an ethyl group, a butyl group, or a 2-ethylhexyl group; An acrylic copolymer with a functional group-containing (meth) acrylic monomer such as (meth) acrylic acid or 2-hydroxyethyl (meth) acrylate is preferably used. The pressure-sensitive adhesive layer containing such an acrylic copolymer does not cause adhesive residue or the like on the glass substrate when it is necessary to peel off after having been bonded to the liquid crystal cell 40, It can be peeled relatively easily. The acrylic copolymer used for the pressure-sensitive adhesive preferably has a glass transition temperature of 25 ° C. or lower, more preferably 0 ° C. or lower. The acrylic copolymer usually has a weight average molecular weight of 100,000 or more.

  As the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer 27, a diffusion pressure-sensitive adhesive in which a light diffusing agent is dispersed can be used. The light diffusing agent is for imparting light diffusibility to the pressure-sensitive adhesive layer. The light diffusing agent may be fine particles having a refractive index different from that of the base polymer constituting the pressure-sensitive adhesive layer, and fine particles made of an inorganic compound or fine particles made of an organic compound (polymer) can be used. Since the base polymer constituting the pressure-sensitive adhesive layer, including the acrylic base polymer as described above, often has a refractive index of about 1.4, the light diffusing agent has a refractive index of about 1-2. May be selected as appropriate. The difference in refractive index between the base polymer constituting the pressure-sensitive adhesive layer and the light diffusing agent is usually 0.01 or more, and from the viewpoint of ensuring the brightness and visibility of the applied liquid crystal display device 1, it is 0.01 or more. It is preferable that it is 0.5 or less. The fine particles used as the light diffusing agent are preferably spherical and those close to monodisperse, and fine particles having an average particle diameter of about 2 to 6 μm are preferably used.

  Examples of the fine particles made of an inorganic compound include aluminum oxide (refractive index 1.76) and silicon oxide (refractive index 1.45). Examples of the fine particles composed of an organic compound (polymer) include melamine resin beads (refractive index 1.57), polymethyl methacrylate beads (refractive index 1.49), methyl methacrylate / styrene copolymer resin beads ( (Refractive index 1.50 to 1.59), polycarbonate beads (refractive index 1.55), polyethylene beads (refractive index 1.53), polystyrene beads (refractive index 1.6), polyvinyl chloride beads (refractive index 1. 46), silicone resin beads (refractive index 1.46), and the like.

  The amount of the light diffusing agent is appropriately determined in consideration of the haze value required for the pressure-sensitive adhesive layer in which it is dispersed, the brightness of the liquid crystal display device 1 to which it is applied, etc. The amount is about 3 to 30 parts by weight with respect to 100 parts by weight of the base polymer constituting the agent layer.

  The haze value measured according to JIS K 7361 of the pressure-sensitive adhesive layer in which the light diffusing agent is dispersed is from the viewpoint of ensuring the brightness of the liquid crystal display device 1 to be applied and making the display image less likely to bleed or blur. A range of 20 to 80% is preferable.

  Each component (base polymer, light diffusing agent, crosslinking agent, etc.) constituting the transparent pressure-sensitive adhesive or diffusion pressure-sensitive adhesive is dissolved in a suitable solvent such as ethyl acetate to form a pressure-sensitive adhesive composition. However, components that are not soluble in a solvent such as a light diffusing agent are dispersed. The pressure-sensitive adhesive layer 27 can be formed by applying this pressure-sensitive adhesive composition on the retardation film 23 or a release film (not shown) and drying it.

  The pressure-sensitive adhesive layer 27 preferably has antistatic properties in order to eliminate static electricity charged on the polarizing plate 20. The polarizing plate 20 may be charged with static electricity when a release film (not shown) laminated on the pressure-sensitive adhesive layer 27 is peeled off and bonded to the liquid crystal cell 40. At this time, if the pressure-sensitive adhesive layer 27 has antistatic properties, the static electricity is quickly eliminated, and the display circuit of the liquid crystal cell 40 is prevented from being broken and the liquid crystal molecules are prevented from being disturbed in alignment. The

  Examples of a method for imparting antistatic properties to the pressure-sensitive adhesive layer 27 include a method in which the pressure-sensitive adhesive composition contains metal fine particles, metal oxide fine particles, or fine particles coated with a metal, etc .; electrolyte salt and organopolysiloxane And a method of incorporating an organic salt antistatic agent. The required antistatic holding time is at least about 6 months from the viewpoint of production, distribution, and storage period of a general polarizing plate.

  The adhesive layer 27 may pass active energy rays in order to cure the adhesive layer. Therefore, it is preferable to have a high transmittance in the corresponding spectral region of the active energy ray. In addition, it is preferable that various characteristics as an adhesive do not change by irradiation of an active energy ray.

  For example, the pressure-sensitive adhesive layer 27 is aged for about 3 to 20 days in an environment of a temperature of 23 ° C. and a relative humidity of 65%, and after the reaction of the cross-linking agent sufficiently proceeds, the pressure-sensitive adhesive layer 27 is used for bonding to the liquid crystal cell 40. The

  The thickness of the pressure-sensitive adhesive layer 27 is appropriately determined according to the adhesive force and the like, but is usually about 1 to 40 μm. In order to obtain a thin polarizing plate without impairing properties such as workability and durability, the thickness of the pressure-sensitive adhesive layer is preferably about 3 to 25 μm. Moreover, when using the adhesive layer in which the light diffusing agent is dispersed, the brightness when the liquid crystal display device 1 is viewed from the front or obliquely is set by setting the thickness of the adhesive layer 27 within this range. It is possible to keep the display image from blurring and blurring.

(5) Adhesive layer (not shown)
The retardation film 23 and the outer resin film 25 are usually bonded to the polarizing film 21 via an adhesive layer. The adhesive that forms the adhesive layer provided on both surfaces of the polarizing film 21 may be the same or different.

  As the adhesive, an adhesive having an epoxy resin, urethane resin, cyanoacrylate resin, acrylamide resin, or the like as an adhesive component can be used. One of the adhesives preferably used is a solventless type adhesive. Solventless adhesives do not contain a significant amount of solvent, and are curable compounds (monomers or oligomers) that are reactively cured by heating or irradiation with active energy rays (for example, ultraviolet rays, visible light, electron beams, X-rays, etc.) ), And an adhesive layer is formed by curing of the curable compound, and typically includes a curable compound that is reactively cured by heating or irradiation of active energy rays, and a polymerization initiator. In particular, when the retardation film 23 or the outer resin film 25 is a resin film with low moisture permeability, water drainage is poor when an aqueous adhesive is used, and the polarizing film 21 is damaged by the moisture of the adhesive or the polarization performance is deteriorated. May cause. Therefore, when bonding such a resin film with low moisture permeability, a solventless adhesive is preferable.

  From the viewpoint of rapid curing and productivity improvement of the polarizing plate 20 associated therewith, as an example of a preferable adhesive for forming the adhesive layer, an active energy ray-curable adhesive that is cured by irradiation with active energy rays can be mentioned. it can. As an example of such an active energy ray-curable adhesive, for example, a photo-curable adhesive that is cured by light energy such as ultraviolet light and visible light can be cited. As the photocurable adhesive, those that are cured by cationic polymerization are preferable from the viewpoint of reactivity, and in particular, the solventless epoxy adhesive using an epoxy compound as a curable compound includes the polarizing film 21 and the retardation film. 23 and the outer resin film 25 are more preferable because of excellent adhesion.

  Although it does not restrict | limit especially as an epoxy compound which is a sclerosing | hardenable compound contained in the said solventless type epoxy adhesive, The thing hardened | cured by cationic polymerization is preferable. In particular, from the viewpoint of weather resistance and refractive index, it is more preferable to use an epoxy compound that does not contain an aromatic ring in the molecule. Examples of such epoxy compounds that do not contain an aromatic ring in the molecule include hydrides of aromatic epoxy compounds, alicyclic epoxy compounds, and aliphatic epoxy compounds. In addition, the epoxy compound that is a curable compound usually has two or more epoxy groups in the molecule.

  After laminating the retardation film 23 and the outer resin film 25 to the polarizing film 21 through an adhesive layer made of an uncured epoxy adhesive, the adhesive film is bonded by irradiating active energy rays or heating. The agent layer is cured, and the retardation film 23 and the outer resin film 25 are fixed on the polarizing film 21. In the case of curing by irradiation with active energy rays, ultraviolet rays are preferably used. Specific examples of the ultraviolet light source include a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, a black light lamp, and a metal halide lamp. The irradiation intensity and irradiation amount of active energy rays such as ultraviolet rays are appropriately selected so as to sufficiently activate the cationic polymerization initiator and not adversely affect the cured adhesive layer, the polarizing film 21 and the like. . In addition, when cured by heating, it can be heated by a generally known method, and the temperature and time at that time can sufficiently activate the cationic polymerization initiator, and the cured adhesive layer or It is appropriately selected so as not to adversely affect the film such as the polarizing film 21.

  The thickness of the adhesive layer comprising the cured epoxy adhesive obtained as described above is usually 50 μm or less, preferably 20 μm or less, more preferably 10 μm or less, and usually 1 μm or more.

  Further, from the viewpoint of thinning the adhesive layer, an aqueous adhesive, that is, an adhesive in which an adhesive component is dissolved in water or an adhesive component is dispersed in water can also be used as the adhesive. For example, an aqueous composition using a polyvinyl alcohol resin or a urethane resin as a main component can be mentioned as a preferred aqueous adhesive.

  A conventionally known method can be used as a method of laminating each film. For example, the polarizing film 21 and / or the film to be bonded to it by the casting method, Meyer bar coating method, gravure coating method, comma coater method, doctor blade method, die coating method, dip coating method, spraying method, etc. The method of apply | coating an adhesive agent to a surface and superimposing both is mentioned. The casting method is a method of spreading and spreading an adhesive on the surface of a film to be coated while moving the film in a substantially vertical direction, a substantially horizontal direction, or an oblique direction between the two.

  In order to improve adhesiveness, the surface of each film may be appropriately subjected to surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, and saponification treatment. Examples of the saponification treatment include a method of immersing in an aqueous alkali solution such as sodium hydroxide or potassium hydroxide.

  The laminated body joined through the water-based adhesive is usually subjected to a drying treatment, and the adhesive layer is dried and cured. The drying process can be performed, for example, by blowing hot air. A drying temperature is normally selected from the range of about 40-100 degreeC, Preferably it is 60-100 degreeC. The drying time is, for example, about 20 to 1,200 seconds. The thickness of the adhesive layer after drying is usually about 0.001 to 5 μm, preferably 0.01 μm or more, preferably 2 μm or less, more preferably 1 μm or less. If the thickness of the adhesive layer becomes too large, the appearance of the polarizing plate 20 tends to be poor.

(Lamination of polarizing film 21, retardation film 23 and outer resin film 25)
Next, the bonding method of the polarizing film 21 and the retardation film 23, and the polarizing film 21 and the outer resin film 25 will be described. The polarizing plate 20 can be manufactured by a known method such as sheet-to-sheet bonding, sheet-to-roll bonding (also referred to as roll-to-sheet bonding), roll-to-roll bonding method, and the like. it can. The sheet-to-sheet bonding method is a method in which a polarizing film and a resin film (retardation film or outer resin film) are both chip-cut into a single sheet and bonded. In addition, the sheet-to-roll bonding method is a method in which one of the polarizing film and the resin film is a roll film, and the other film is chip-cut into a sheet and bonded to the roll film. . The roll-to-roll bonding method is a method of bonding a roll-shaped polarizing film and a roll-shaped resin film.

  When the polarizing film 21 and the outer resin film 25 are bonded together, the surface of the polarizing film 21 that is bonded to the outer resin film 25 is subjected to a corona discharge treatment, and is bonded to the outer resin film 25 through this processed surface. It is preferable to match. By performing the surface treatment in this way, the adhesion between the polarizing film 21 and the outer resin film 25 becomes good. The same applies when the polarizing film 21 and the retardation film 23 are bonded together.

(B) Polarizing plate 30 (second polarizing plate)
Next, the polarizing plate 30 will be described. The polarizing plate 30 is used as a viewing side (front side) polarizing plate of the liquid crystal panel 2. The polarizing plate 30 corresponds to the second polarizing plate of the present invention. The polarizing plate 30 has a layer configuration in which an outer resin film 35, a polarizing film 31, a retardation film 33, and an adhesive layer 37 are laminated in this order. Hereinafter, each layer constituting the polarizing plate 30 will be described.

(1) Polarizing film 31 (second polarizing film)
The polarizing film 31 corresponds to the second polarizing film of the present invention. As the polarizing film 31, as in the polarizing film 21 described above, a film obtained by adsorbing and orienting a dichroic dye on a uniaxially stretched polyvinyl alcohol-based resin film can be used. The polarizing film 21 and the polarizing film 31 may be the same or different with respect to the outer shape (thickness, etc.), material, and manufacturing method.

(2) Retardation film 33 (second retardation film)
The retardation film 33 is a retardation film disposed between the polarizing film 31 and the pressure-sensitive adhesive layer 37 and has an optical compensation function that widens the viewing angle when bonded to the liquid crystal cell 40. The retardation film 33 corresponds to the second retardation film of the present invention. Similar to the retardation film 23, the retardation film 33 has an in-plane retardation value R ₀ in the range of 30 to 200 nm, a thickness direction retardation value R _th in the range of 100 to 350 nm, and biaxial cellulose. It is a retardation film made of a resin. The phase difference film 23 and the phase difference film 33 may be the same as or different from each other in terms of the outer shape (thickness, etc.), material, and manufacturing method.

(3) Outer resin film 35 (second outer resin film)
The outer resin film 35 is a resin film laminated on the outer side of the polarizing film 31. The outer resin film 35 corresponds to the second outer resin film of the present invention. As the outer resin fill 35, any resin material can be used, but one composed of a transparent resin is preferable. Examples of such resin materials include (meth) acrylic resins such as methyl methacrylate resin ((meth) acrylic resin means methacrylic resin or acrylic resin), olefinic resin, Vinyl chloride resin, cellulose resin, styrene resin, acrylonitrile / butadiene / styrene copolymer resin, acrylonitrile / styrene copolymer resin, polyvinyl acetate resin, polyvinylidene chloride resin, polyamide resin, polyacetal resin , Polycarbonate resins, modified polyphenylene ether resins, polyester resins (for example, polybutylene terephthalate resins, polyethylene terephthalate resins, etc.), polysulfone resins, polyethersulfone resins, polyarylate resins, polyamideimide resins , Polyimide resins, epoxy resins, oxetane resins. These resins can contain additives as long as they do not impair transparency and adhesiveness with a polarizing film.

  As the outer resin film 35, for example, a protective film can be employed. Since the protective film is as described in the outer resin film 25 described above, detailed description thereof is omitted here.

  Further, an antiglare film can be adopted as the outer resin film 35. As an anti-glare film, the thing in which the hard-coat layer which has a fine uneven | corrugated shape on the surface can be mentioned. Such a hard coat layer is formed by a method of forming a coating film containing organic fine particles or inorganic fine particles on the surface of the base film, or after forming a coating film containing or not containing organic fine particles or inorganic fine particles. The film can be manufactured by a method (for example, an embossing method) or the like that presses the film against the uneven surface of a roll having an uneven shape.

  Furthermore, the outer resin film 35 is not limited to the above-described protective film or antiglare film, and may be another functional film. For example, a film having functions such as antireflection, low reflection, antifouling, and antistatic may be used.

[Anti-reflective / low-reflective properties (anti-reflective / low-reflective film)]
In general, the antireflection film is formed by stretching a low refractive index layer that is also an antifouling layer and at least one layer having a higher refractive index than that of the low refractive index layer (that is, a high refractive index layer or a medium refractive index layer). It is formed by being provided on a resin film such as unstretched cellulose acetate.

  As a multilayer film in which transparent thin films of inorganic compounds (metal oxides, etc.) with different refractive indexes are laminated, colloid by chemical vapor deposition (CVD) method, physical vapor deposition (PVD) method, metal compound sol / gel method such as metal alkoxide And a method of forming a thin film by post-treatment (ultraviolet irradiation: JP-A-9-157855, plasma treatment: JP-A-2002-327310) after forming the metal oxide particle film.

  On the other hand, various antireflection films have been proposed as antireflection films having high productivity, in which a thin film in which inorganic particles are dispersed in a matrix is laminated. Moreover, the antireflection film which consists of an anti-glare antireflection layer which gave the shape of the fine unevenness | corrugation to the uppermost layer surface of such an antireflection film by application | coating is also mentioned.

[Granting antifouling properties]
For the purpose of imparting properties such as antifouling properties, water resistance, chemical resistance, and slipperiness, a known silicone-based or fluorine-based antifouling agent, slipping agent, etc., may be appropriately added to a cellulose acetate-based resin film. You can also. When these additives are added, it is preferably added in the range of 0.01 to 20% by mass, more preferably in the range of 0.05 to 10% by mass of the total solid content of the low n layer. Particularly preferably 0.1 to 5% by mass.

[Addition of dustproof / antistatic layer]
For the purpose of imparting dustproof and antistatic properties, a known antistatic agent such as a cationic surfactant or a polyoxyalkylene compound, an antistatic agent, or the like can be appropriately added to a resin film such as cellulose acetate. . These dustproofing agent and antistatic agent may contain the structural unit as a part of the function in the above-mentioned silicone compound or fluorine compound. When these are added as additives, it is preferably added in the range of 0.01 to 20% by mass, more preferably in the range of 0.05 to 10% by mass of the total solid content of the low n layer. Particularly preferably 0.1 to 5% by mass.

(4) Adhesive layer 37 (second adhesive layer)
The pressure-sensitive adhesive layer 37 corresponds to the second pressure-sensitive adhesive layer of the present invention. As the pressure-sensitive adhesive layer 37, those described in the pressure-sensitive adhesive layer 27 can be similarly used. The pressure-sensitive adhesive layer 27 and the pressure-sensitive adhesive layer 37 may be the same or different with respect to the outer shape (thickness and the like), the material, the manufacturing method, and the like.

(Bonding of polarizing film 31, retardation film 33 and protective film 35)
Bonding of the polarizing film 31 and the retardation film 33 and the polarizing film 31 and the protective film 35 can be performed by the same method as that described for the polarizing plate 20. The adhesive forming the adhesive layer provided on both surfaces of the polarizing film 31 may be the same or different. Moreover, the adhesive used for preparation of the polarizing plate 20 and the adhesive used for preparation of the polarizing plate 30 may be the same or different.

<Liquid crystal panel 1 and liquid crystal display device 2>
FIG. 2 is a schematic cross-sectional view showing an example of a basic layer configuration of the liquid crystal panel 2 and the liquid crystal display device 1. The liquid crystal display device 1 shown in this figure includes a liquid crystal panel 2, a backlight 10, and a light diffusion plate 50. The liquid crystal panel 2 includes a liquid crystal cell 40, a polarizing plate 20 as a back side polarizing plate bonded to one surface of the liquid crystal cell 40, and a front side polarizing plate bonded to the other surface of the liquid crystal cell 40. Polarizing plate 30. The polarizing plate 20 has a configuration in which the polarizing film 21 is sandwiched between the retardation film 23 and the outer resin film 25, and the adhesive film 27 is interposed therebetween so that the retardation film 23 faces the liquid crystal cell 40. The liquid crystal cell 40 is pasted. The polarizing plate 30 has a configuration in which an outer resin film 35 and a polarizing film 31 are laminated, and the liquid crystal cell 40 is interposed via the adhesive layer 37 so that the retardation film 33 faces the liquid crystal cell 40. Is pasted. In the liquid crystal display device 1, the liquid crystal panel 2 is arranged so that the polarizing plate 20, which is a back side polarizing plate, is on the backlight 10 side, that is, the outer resin film 25 faces the light diffusion plate 50.

  The liquid crystal cell 40 is an element that displays an image by electrically controlling a cell in which a liquid crystal material is sealed between glass substrates. The type of the liquid crystal cell 40 is not particularly limited, but is preferably a VA mode liquid crystal cell 40. In the VA mode, since the luminance varies depending on whether it is viewed from the front of the liquid crystal display device or from an oblique direction, it is necessary to widen the viewing angle, and at least one biaxial retardation film is required. Because.

  The liquid crystal panel 2 and the liquid crystal display device 1 can be manufactured by a known method. As a manufacturing method of the liquid crystal panel 2, the long polarizing plate 20 and the polarizing plate 30 wound in a roll shape can be cut into pieces and bonded to the liquid crystal cell 40.

  When the liquid crystal panel 2 is formed using the VA mode liquid crystal cell 40, the absorption axes of the polarizing plate 20 and the polarizing plate 30 are generally orthogonal to each other (crossed Nicols), and these absorption axes are rectangular. The liquid crystal cell 40 is parallel to the long side direction or the short side direction.

  The backlight 10 is a device for illuminating the liquid crystal cell 40. Examples of the type of the backlight 10 include an edge light type and a direct type. The edge-light type backlight 10 irradiates light to the liquid crystal cell 40 through a light guide plate from a light source such as a cold cathode tube or an LED arranged on a side surface. In the direct type backlight 10, a light source is disposed on the back side of the liquid crystal cell 40 to irradiate the liquid crystal cell 40 with light. As the type of the backlight 10, a backlight according to the application of the liquid crystal display device 1 can be appropriately adopted.

  The light diffusing plate 50 is an optical member having a function of diffusing light from the backlight 10, for example, a material in which particles as a light diffusing agent are dispersed in a thermoplastic resin to impart light diffusibility, thermoplasticity The surface of the resin film may be uneven to provide light diffusibility, or the resin film may be provided with a coating layer of a resin composition in which particles are dispersed on the surface of the thermoplastic resin film. . The thickness can be about 0.1-5 mm.

  Between the light diffusing plate 50 and the liquid crystal panel 2, a sheet or film exhibiting other optical functionality such as a brightness enhancement sheet (a reflective polarizing film (such as “DBEF”)) or a light diffusing sheet is disposed. You can also Two or more sheets or films exhibiting other optical functionalities can be arranged as needed.

(Second Embodiment)
Next, a set of polarizing plates relating to the second embodiment of the present invention will be described. In the first embodiment described above, the outer resin film 25 of the polarizing plate (polarizing plate 20) on the back side of the liquid crystal cell 40 is made of an acrylic resin, and the outer resin film 35 of the polarizing plate (polarizing plate 30) on the viewing side. Was a configuration made of an arbitrary resin. However, in the present invention, any film may be used as long as at least one of the outer resin film 25 and the outer resin film 35 is made of an acrylic resin.

In the present embodiment, the outer resin film 25 is an arbitrary resin film, and the outer resin film 35 is a film made of an acrylic resin. As an arbitrary resin in this case, an arbitrary resin material as described in the outer resin film 35 in the first embodiment described above can be used.
The outer resin film 35 is composed of a film made of an acrylic resin. As such an acrylic resin, an acrylic resin as described in the outer resin film 25 in the first embodiment described above can be used.

(Third embodiment)
Next, a set of polarizing plates relating to the third embodiment of the present invention will be described. In the present embodiment, both the outer resin film 25 of the polarizing plate (polarizing plate 20) on the back side of the liquid crystal cell 40 and the outer resin film 35 of the polarizing plate (polarizing plate 30) on the viewing side are made of acrylic resin. . As such an acrylic resin, an acrylic resin as described in the outer resin film 25 in the first embodiment described above can be used.

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device, 2 Liquid crystal panel, 10 Backlight, 20 Polarizing plate (1st polarizing film), 21 Polarizing film (1st polarizing film), 23 Retardation film (1st retardation film), 25 Outer Resin film (first outer resin film), 27 pressure-sensitive adhesive layer (first pressure-sensitive adhesive layer), 30 polarizing plate (second polarizing plate), 31 polarizing film (second polarizing film), 33 retardation film (Second retardation film), 35 outer resin film (second outer resin film), 37 adhesive layer (second adhesive layer) 40 liquid crystal cell, 50 light diffusion plate

Claims (7)

The first retardation film, the first polarizing film, and the first outer resin film are laminated in this order, and are polarizing plates used by being bonded to a liquid crystal cell,
The first retardation film is composed of a biaxial cellulose-based resin having an in-plane retardation value in the range of 30 to 200 nm and a thickness direction retardation value in the range of 100 to 350 nm.
The first outer resin film is made of an acrylic resin composition in which 25 to 45% by weight of rubber elastic particles having a number average particle size of 10 to 300 nm are blended in a transparent acrylic resin, and the internal haze value is 0. .5% or less and the external haze value is 5% or less,
A polarizing plate, wherein the first retardation film, the first polarizing film, and the first outer resin film are disposed in order from the side closer to the liquid crystal cell.   By the adhesive which consists of a resin composition containing the epoxy compound which the said 1st polarizing film, the said 1st phase difference film, the said 1st polarizing film, and the said 1st outer side resin film each harden | cure by an active energy ray The polarizing plate according to claim 1, which is adhered.   The polarizing plate according to claim 1, wherein the rubber elastic body particles include an acrylic elastic polymer. A set of polarizing plates for liquid crystal display comprising a first polarizing plate disposed on the viewing side of the liquid crystal cell and a second polarizing plate disposed on the back side,
Either one of the first polarizing plate and the second polarizing plate is the polarizing plate according to claim 1,
The other of the first polarizing plate and the second polarizing plate is formed by laminating a second retardation film, a second polarizing film, and a second outer resin film in this order, and the liquid crystal In order from the side closer to the cell, the second retardation film, the second polarizing film, and the second outer resin film are arranged to be positioned,
The second retardation film has an in-plane retardation value at a wavelength of 590 nm in the range of 30 to 200 nm, a thickness direction retardation value at a wavelength of 590 nm in the range of 100 to 350 nm, and from the biaxial cellulose-based resin film. A set of polarizing plates characterized by It consists of a liquid crystal cell and a pair of polarizing plates arranged on both sides thereof,
The pair of polarizing plates is a set of polarizing plates according to claim 4,
The first outer resin film, the first polarizing film, the first retardation film, the liquid crystal cell, the second retardation film, the second polarizing film, and the second outer resin film are laminated in this order. A liquid crystal panel characterized by A backlight, a light diffusing plate, and a liquid crystal panel according to claim 5,
The liquid crystal display device, wherein the backlight, the light diffusing plate, the second polarizing plate, the liquid crystal cell, and the first polarizing plate are arranged in this order.   The liquid crystal panel liquid crystal display device according to claim 6, wherein the liquid crystal cell is a VA mode liquid crystal cell.

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