KR20070065336A - Polarizing plate and liquid crystal display - Google Patents

Abstract

A polarizing plate comprising a polarizer comprising polyvinyl alcohol and a protective film on at least one side of the polarizer, the polarizer having a difference of 5.0% or smaller between maximum and minimum of an in-plane phase difference Rpva thereof in any area thereof measuring 39 cm wide and 65 cm long.

Description

Polarizers and Liquid Crystal Displays {POLARIZING PLATE AND LIQUID CRYSTAL DISPLAY}

Field of technology

The present invention relates to a polarizing plate having a polarizer having a substantially uniform in-plane phase transition, and a liquid crystal display (hereinafter referred to as LCD) in which stripe unevenness in density is eliminated by using the polarizing plate.

Background

LCDs are widely applied to monitors of personal computers, mobile devices, and TV sets in terms of various advantages such as low voltage, low power consumption, and allowing for reduction in size and thickness. Various modes have been proposed for LCDs depending on the orientation of liquid crystal molecules of the liquid crystal cell. Twisted nematic (TN) mode was the mainstream, in which the orientation direction of the liquid crystal molecules is twisted by about 90 ° from one side of the cell to the other.

LCDs generally consist of liquid crystal cells, optical compensation films, and polarizers. The optical compensation film serves to remove image discoloration or to enlarge a viewing angle, and includes a stretched birefringent film and a transparent film coated with a liquid crystal compound. Japanese Patent No. 2587398 discloses a technique for expanding the viewing angle in a TN mode liquid crystal cell using an optical compensation film prepared by applying a discotic liquid crystal compound to a triacetyl cellulose film, orienting the liquid crystal molecules, and fixing the orientation. Initiate. However, even such state-of-the-art technology is still unsatisfactory in the application of LCD TVs, which are expected to be viewed at a wide angle with a wide screen and eventually have a reduced viewing angle dependency. In this situation, LCD modes different from TN modes have been studied, including IPS (in-plane switching) mode, OCB (optical compensation band optically compensatory bend) mode, and VA (vertically aligned) mode. do. In particular, VA mode is drawing attention for TV monitor applications due to its high contrast and relatively high production rate.

Usually, polyvinyl alcohol (hereinafter referred to as PVA) is generally used as the material of the polarizer essential for LCD. The PVA film may be uniaxially stretched and then dyed with iodine or dichroic dye, or may be dyed first and lost, and then crosslinked with a boron compound to form a polarizer (polarizing film).

Cellulose acylate films are characterized by having higher optical anisotropy (low retardation values) compared to other polymer films. Therefore, it is common to use a cellulose acylate film for the application which requires optical anisotropy, such as a protective film of a polarizing plate.

In contrast, optical anisotropy (higher retardation value) is required for the optical compensation film (retardation film). In particular, the optical compensation film for the VA mode is required to have a total retardation (Re) of 30 to 200 nm and a thickness direction retardation (Rth) of 70 to 400 nm. For this reason, synthetic polymer films having high retardation values, such as polycarbonate films or polysulfone films, are commonly used as optical compensation films.

In short, it is a general principle in the field of optical materials to use synthetic polymer films that require optical anisotropy (high retardation values) and to use cellulose acylate films when optical anisotropy (low retardation values) are required. .

Contrary to the general principle, EP 911656 proposes a cellulose acetate film useful for applications with high retardation values and requiring optical anisotropy. According to the above proposal, as a retardation increasing agent for cellulose triacetate, an aromatic compound having two or more aromatic rings, in particular a compound having a 1,3,5-triazine ring, is added, and the cellulose triacetate is drawn by stretching the film. High retardation values of the film are achieved. Since cellulose triacetate is usually difficult to stretch, it is known that it is difficult to increase the birefringence of cellulose triacetate by stretching. According to the EP, co-stretching the additive increases birefringence to achieve high retardation values. This film also functions as a protective film of the polarizing plate, thereby providing a competitive and slim LCD.

JP-A-2002-71957 discloses an optical film containing a cellulose ester having an acyl group having 2 to 4 carbon atoms as a substituent. The acyl group substituent satisfies the formula: 2.0 ≦ A + B ≦ 3.0 and A <2.4, where A is the degree of substitution of acetyl and B is the degree of substitution of propionyl or butyryl. The refractive index Nx in the slow axis direction of the optical film and the refractive index Ny in the fast axis direction both satisfy the formula: 0.0005 ≦ Nx−Ny ≦ 0.0050 at 590 nm.

 JP-A-2003-270442 discloses polarizers for use in VA mode LCDs. The polarizing plate comprises a polarizer and an optical biaxial, mixed fatty acid cellulose ester film. In the polarizing plate, a cellulose ester film is disposed between the liquid crystal cell and the polarizer.

JP-A-2002-333523 discloses a polarizing plate having an in-plane retardation (Δnd) of 500 to 1000 nm and an LCD having the polarizing plate. The proposed polarizer exhibits high contrast properties and high dimensional safety due to reduced residual stress.

The prior art described above is effective for providing a cheap and thin LCD. On the other hand, LCD technology is rapidly increasing the application for television in recent years. Since LCD-TVs have a brighter backlight than other LCD monitors, display unevenness becomes more pronounced. In particular, wide-screen LCD-TVs require wide but uniform screen characteristics. Thus, polarizers for such applications require that a wide area have a uniform quality.

Wide polarizer plates currently available lack the stretching uniformity, ie it is worsened by uneven stretching. Non-uniform stretching is mainly due to non-uniform orientation of PVA. The nonuniformity can be assessed by the variables of the in-plane retardation Rpva of the PVA correlated with the orientation of the PVA.

The stretching orientation nonuniformity of PVA tends to occur in a direction perpendicular to the stretching direction, and appears as a striped nonuniformity in terms of density when the LCD receives light from the back side. The use of such polarizers in wide-screen LCDs causes streaking defects on the screen. For this reason, development of a polarizing plate with little stretch orientation nonuniformity in PVA has been required.

In JP-A-2002-333523 described above, the in-plane retardation of the polarizing plate is specified and a manufacturing process of the polarizing plate having sufficient optical properties is proposed, but the uniformity of the in-plane retardation value is not considered.

Disclosure of the Invention

It is an object of the present invention to provide a polarizing plate that performs excellent optical compensation function and uniform quality even in a wider area and to provide an LCD using the polarizing plate.

As a result of extensive research, the inventors of the present invention have found that the above object is achieved by using a polarizer having a small stretching orientation unevenness of the PVA film.

The present invention provides a polarizing plate having a polarizer containing polyvinyl alcohol and a protective film provided on at least one side of the polarizer. The polarizer has a deviation of 5.0% or less between the maximum value and the minimum value of the in-plane retardation Rpva in any region having a width of 39 cm and a length of 65 cm.

The present invention provides a preferred embodiment of the polarizer, wherein:

(1) The deviation of the in-plane phase difference Rpva at any two points 1 cm apart is 10 nm or less.

(2) The polarizer is produced by a process comprising swelling a polyvinyl alcohol film and stretching a swelled polyvinyl alcohol, and stretching is biaxially stretching.

(3) The protective film provided on one side of the polarizer has a front retardation value Re (590) and a thickness direction retardation value Rth (590), all at 590 nm wavelengths, and the following formulas (1) and (2) Satisfies:

20nm≤Re (590) ≤200nm (1)

70 nm ≤ Rth (590) ≤ 400 nm (2).

(4) The ratio of Re (590) to Rth (590) is 0.1 to 0.8.

(5) The protective film provided on one side of the polarizer contains, as a main polymer component, a cellulose mixed fatty acid ester having an acyl group and an acetyl group having three or more carbon atoms substituting a hydroxyl group of cellulose. Cellulose acylate film. The cellulose mixed fatty acid ester is represented by the following formula (3) and formula (4):

2.0≤A + B≤3.0 (3)

0 <B (4)

Where A is the degree of substitution by the acetyl group; And B is a degree of substitution by an acyl group having 3 or more carbon atoms.

(6) The acyl group having three or more carbon atoms is a butanoyl group.

(7) The acyl group having three or more carbon atoms is a propionyl group.

(8) The protective film provided on one side of the polarizer is a cellulose acylate film having an acyl group containing two or more carbon atoms, the following formula (5) and formula (6):

2.0≤DS2 + DS3 + DS6≤3.0 (5)

DS6 / (DS2 + DS3 + DS6) ≥0.315 (6)

Where DS2, DS3, and DS6 each represent a degree of substitution of hydroxyl groups at 2-, 3- and 6-positions of the glucose units constituting cellulose by the acyl groups.

(9) In (8), the acyl group is an acetyl group.

(10) The protective film provided on one side of the polarizer includes at least one of a plasticizer, an ultraviolet absorber, a release agent, a dye, and a mat agent.

(11) The protective film provided on one side of the polarizer includes at least one retardation enhancer selected from rod-shaped compounds and discotic compounds.

(12) The protective film provided on one side of the polarizer includes a polymer film and an optically anisotropic layer.

(13) The polarizing plate further includes at least one of a hard coat layer, an antiglare layer, and an antireflection layer on a protective film disposed on the other side of the polarizer.

(14) The polarizing plate further includes a retardation film attached through an adhesive to the protective film provided on one side of the polarizer.

 The present invention also provides an LCD having a protective film facing the liquid crystal cell and the polarizing plate of the present invention.

The polarizing plate according to the present invention is accompanied by a reduced nonuniformity of the stretching orientation of the polarizer. The use of the polarizing plate according to the present invention provides an LCD having a uniform display quality even in a wide area.

Brief description of the drawings

1 schematically shows a layer structure of a polarizing plate embodiment according to the present invention.

2 schematically shows the structure of a liquid crystal display embodiment according to the present invention.

Reference numerals used to define various structural features in the figures include the following.

1, 11, 21: polarizer

4: functional layer

5, 15, 25: polarizer

Optimal for carrying out the invention mode

The polarizing plate of the present invention has a polarizer containing polyvinyl alcohol and a protective film provided on at least one side of the polarizer. The polarizer has a deviation of 5.0% or less between the maximum value and the minimum value of the in-plane retardation Rpva in any region having a width of 39 cm and a length of 65 cm.

The 39 cm wide and 65 cm long region referred to in the present invention corresponds to the screen of a 30 inch LCD TV and can be seen as a criterion for evaluating the applicability for wide screen LCD.

The polarizing plate is usually composed of a polarizer and a transparent protective film disposed on each side of the polarizer. The polarizing plate according to the present invention preferably has a specific optical cellulose acylate film (to be described later) as a protective film provided on at least one side of the polarizer. The protective film provided on the other side may be a specific cellulose acylate film or a conventional cellulose acylate film. In the present invention, uniform display quality of the polarizing plate is achieved by reducing the thickness change in the width direction of the polarizer.

Polarizers include iodine polarizers, dichroic polarizers, and polyene polarizers. Iodine polarizers and dichroic polarizers are usually made using PVA films. The polarizer usable in the present invention is preferably a PVA dichroic polarizer composed of PVA and dichroic molecules.

PVA is a polymeric material obtained by saponification of polyvinyl acetate. It may comprise components which are copolymerizable with vinyl acetate, such as unsaturated carboxylic acids, unsaturated sulfonic acids, olefins or vinyl ethers. Modified PVAs, including acetoacetyl groups, sulfonic acid groups, carboxyl groups, oxyalkylene groups and the like, are of course useful.

Although the degree of saponification of PVA is not limited, Preferably it is 80-100 mol%, More preferably, it is 90-100 mol%. The degree of polymerization of PVA is preferably 1000 to 3800, more preferably 1500 to 3800.

PVA preferably has a degree of syndiotacticity of at least 55% in order to have improved durability, as described in Japanese Patent No. 2978219. As described in Japanese Patent No. 3317494, PVA having an alternating degree of 45 to 52.5% is also preferably used.

PVA-based dichroic polarizers are preferably prepared by first forming PVA into a film and then introducing dichroic molecules. The PVA film is preferably prepared by molding the PVA solution in water or an organic solvent, as is usually done. The concentration of PVA solution is usually 5-20% by weight. Molding of the PVA solution causes the PVA film to have a thickness of 10 to 200 μm. For details of PVA film molding, Japanese Patent No. 3342516, JP-A-9-328593, JP-A-13-302817, and JP-A-14-144401 can be referred to.

The crystallinity of the PVA film is not particularly limited. For example, a PVA film having an average crystallinity (Xc) of 50 to 75% by weight disclosed in Japanese Patent No. 3251073 and a PVA film having a crystallinity of 38% or less disclosed in JP-A-14-236214 can be used. .

It is preferable that birefringence ((DELTA) n) of a PVA film is as small as possible. PVA films having birefringence of 1.0 × 10 ^-3 or less disclosed in Japanese Patent No. 3342156 are preferably used. On the other hand, as proposed in JP-A-14-228835, a birefringent PVA film of 0.02-0.01 is used in order to obtain high polarization while avoiding a break during film stretching, or described in JP-A-14-60505. As described above, a PVA film having a birefringence that satisfies the formula: 0.0003 ≦ (nx + ny) /2-nz≦0.01 may be used. The PVA film preferably has an in-plane retardation of 0 to 100 nm, more preferably 0 to 50 nm, and preferably has a thickness direction retardation (Rth) of 0 to 500 nm, more preferably 0 to 300 nm.

Other PVA films preferably used in the present invention for forming polarizers have a 1,2-glycol bond content of 1.5 mol% or less, as described in Japanese Patent No. 3021494, in JP-A-13-316492. It does not contain more than 500 optical foreign substances of more than 5㎛ per 100cm2 as described, and has a water jet temperature change of less than 1.5 ℃ in TD as proposed in JP-A-14-30163 for hot water jet cutting Prepared by, tri-hydric alcohol to hexa-hydric alcohol, for example, prepared from PVA solution containing 1 to 100 parts by weight of glycerin, and PVA system as disclosed in JP-A-6-289225 And those made with a PVA solution comprising at least 15% by weight of plasticizer.

The thickness of the non-stretched PVA film is not particularly limited, but is preferably 1 µm to 1 mm, more preferably 20 to 200 µm in view of handling stability and stretching uniformity. As described in JP-A-14-236212, it is possible to use a PVA film that is thin enough to generate a stress of 10 N or less when drawn in water with 4 to 6 layers.

Dichroic molecules that can preferably be used to color the PVA film include higher-order iodine ions such as I ₃ or I ₅ and dichroic dyes. Higher order iodine ions are particularly preferred in the present invention. Nagata Ryo (ed.), Henkoban no oyo, CMC Publishing Co., Ltd. And Kogyo zairyo, vol. 28, no. 7, pp. As described in 39-45, in order to have higher order iodine ions absorbed and arranged inside the PVA film, the PVA film is immersed in an aqueous potassium iodide solution and / or an aqueous boric acid solution in which iodine is dissolved.

When using dichroic dyes as dichroic molecules, azo dyes, in particular Biazo dyes and triazo dyes, are preferred. It is preferable that a dichroic dye is water-soluble. To obtain a water soluble dichroic dye, hydrophilic substituents such as sulfonic acid groups, amino groups or hydroxyl groups are introduced into the dichroic molecules to form free acids or salts with alkali metals, ammonium or amines.

 Examples of useful dichroic dyes are C.I. Direct red 37, Congo Red (C.I. direct red 28), C.I. Direct purple 12, C.I. Direct blue 90, C.I. Direct blue 22, C.I. Direct blue 1, C.I. Direct blue 151, and C.I. Benzidine dyes such as direct green 1; C.I. Direct yellow 44, C.I. Direct red 23, and C.I. Diphenylurea dyes such as direct red 79; C.I. Stilbene dyes such as direct yellow 12; C.I. Dinaphthylamine dyes such as direct red 31; And C.I. Direct red 81, C.I. Direct purple 9, and C.I. Direct acid dyes such as blue 78.

JP-A-62-70802, JP-A-1-161202, JP-A-1-172906, JP-A-1-172907, JP-A-1-183602, JP-A-1-248105, JP- CI disclosed in A-1-265205, and JP-A-7-261024 Direct yellow 8, C.I. Direct yellow 28, C.I. Direct yellow 86, C.I. Direct yellow 87, C.I. Direct yellow 142, C.I. Orange 26, C.I. Direct orange 39, C.I. Orange 72, C.I. Orange 106, C.I. Orange 107, C.I. Direct red 2, C.I. Direct red 39, C.I. Direct red 83, C.I. Direct red 89, C.I. Direct red 240, C.I. Direct red 242, C.I. Direct red 247, C.I. Direct purple 48, C.I. Direct purple 51, C.I. Direct purple 98, C.I. Direct blue 15, C.I. Direct blue 67, C.I. Direct blue 71, C.I. Direct blue 98, C.I. Direct blue 168, C.I. Direct blue 202, C.I. Direct blue 236, C.I. Direct blue 249, C.I. Direct blue 270, C.I. Direct green 59, C.I. Direct green 85, C.I. Direct brown 44, C.I. Direct brown 106, C.I. Direct brown 195, C.I. Direct brown 210, C.I. Direct brown 223, direct brown 224, C.I. Direct black 1, C.I. Direct black 17, C.I. Direct black 19, C.I. Direct black 54, dichroic dyes are further included. Two or more dichroic dyes may be used to produce the desired color tone. When using a dichroic dye, the adsorption thickness can be at least 4 μm, as described in JP-A-14-82222.

The dichroic molecular content of the PVA film is usually in the range of 0.01 to 5% by weight, based on the PVA substrate. Too small a content of dichroic molecules results in low polarization, and a content of too large dichroic molecules causes a decrease in transmittance.

The polarizer preferably has a thickness of 5 to 40 µm, more preferably 10 to 35 µm. As suggested in JP-A-14-174727, the thickness ratio of the polarizer to the protective film (to be described later) is preferably 0.01 to 0.16.

The polarizing plate may further have an adhesive, a separation sheet, and a releasable protective sheet in addition to the polarizer described above and a protective film to be described later.

The polarizing plate is manufactured as follows. The polarizing plate is preferably manufactured by a process comprising the steps of swelling, dyeing, curing, stretching, drying, laminating on a protective film, and drying after lamination. The order of the dyeing, curing and stretching steps can be changed as desired. Two or more steps may be performed simultaneously. As in Japanese Patent No. 3331615, the curing step may be performed after washing with water.

The process is preferably carried out in the order of swelling, dyeing, curing / drawing, drying, lamination to the protective film, and drying after lamination. During or after these steps, an online inspection step of the surface state can be provided.

The swelling step is preferably performed using only water. In order to obtain stable optical performance and to avoid wrinkle of the film, an aqueous solution of boric acid can be used to swell the PVA film to a controlled degree. The swelling temperature and time, optionally determined, are preferably 10 to 60 ° C. and 5 to 2000 seconds.

In the dyeing step, the method of JP-A-2002-86554 can be employed. Instead of the immersion method, dyeing can also be carried out by coating or spraying with iodine or dye solution. The dyeing technique proposed in JP-A-13-290025 can be as follows: PVA film is stirred at a specific draw ratio, in a dyeing bath, at a specific dye or iodine concentration, at a particular bath temperature, It is stretched while making it.

When higher order iodine ions are used as dichroic molecules, it is preferable to use an aqueous potassium iodide solution in which iodine is dissolved in order to obtain a polarizer which achieves high contrast. The aqueous iodine-potassium iodide solution preferably has an iodine concentration of 0.05-20 g / l, a potassium iodide concentration of 3-200 g / l, and a weight ratio of iodine / potassium iodide of 1-2000. The solution more preferably has an iodine concentration of 0.05-2 g / l, a potassium iodide concentration of 30-120 g / l, and an iodine / potassium iodide weight ratio of 30-120. The aqueous solution of iodine-potassium iodide is preferably carried out at a bath temperature of 10 to 60 ° C, more preferably 20 to 50 ° C, preferably for 10 to 1200 seconds, more preferably for 30 to 600 seconds.

The dye bath may contain a boron compound such as boric acid or borax, as described in Japanese Patent No. 3145747.

The curing step can be carried out by mixing the crosslinker in the film, preferably by immersion in the crosslinker solution or by coating with the crosslinker solution. The curing step can be made in several divided steps, as described in JP-A-11-52130.

Useful crosslinkers include those described in US Pat. No. 232897. Most preferred are boric acid compounds. Nevertheless, as suggested in Japanese Patent No. 3357109, multifunctional aldehydes can be used to improve the dimensional stability.

When using boric acid as a crosslinking agent, an aqueous solution of boric acid-potassium iodide to which metal ions are added may be used. Zinc chloride is preferably added to the metal ion source. Zinc halides (eg zinc iodide) or zinc salts For example, other zinc sources, such as zinc sulfate or zinc acetate, may be used in place of zinc chloride, as suggested in JP-A-2000-35512.

In the present invention, the curing can preferably be carried out by immersing the PVA film in an aqueous solution of boric acid-potassium iodide containing zinc chloride. The boric acid-potassium iodide aqueous solution containing zinc chloride preferably has a boric acid concentration of 1 to 100 g / l, more preferably 10 to 80 g / l, and preferably 1 to 120 g / l, more preferably 5 to 100 g / l potassium Iodide concentration, and preferably zinc chloride concentration of 0.01 to 10 g / l, more preferably 0.02 to 8 g / l. Curing is preferably carried out at a solution temperature of 10 to 60 ° C., more preferably at a solution temperature of 20 to 50 ° C., preferably for 10 to 1200 seconds, more preferably for 30 to 600 seconds.

The stretching step is preferably carried out by longitudinal monoaxial stretching, as described in US Pat. No. 2,454,515, or tentering, as described in JP-A-2002-86554. The draw ratio is preferably 2 to 12, more preferably 3 to 10. Regarding the relationship between the draw ratio, the unstretched film thickness, and the final polarizer thickness, JP-A-14-40256 described (polarizer thickness / non-stretch film thickness after attaching the protective film) x (total draw ratio)> 0.17 is described. The operation according to the above can be preferably used. Regarding the relationship between the width A of the polarizer and the width B of the polarizer from the final bath, the manipulation of JP-A-14-40247, which describes 0.80 ≦ B / A ≦ 0.95, can be preferably used.

As a result of stretching, the orientation nonuniformity in the final PVA polarizer is within a range where the deviation between the maximum and minimum of the in-plane retardation Rpva is not greater than 5%, i. Should be The deviation is preferably 0% to 4.5%. The deviation is calculated from [(max-min) / min] × 100. The Rpva deviation between any two points 1 cm apart is preferably 10 nm or less, that is, 10 nm / cm or less, more preferably 8 nm / cm or less. In-plane retardation Rpva can be measured with the near infrared retardation measurement system KOBRA-WX100 / IR available from Oji Scientific Instruments.

Larger in-plane retardation Rpva means higher orientation and good optical properties of PVA molecules. If the phase difference Rpva is greater than 5.0%, the well-arranged portion and the incompletely-arranged portion of the polarizer make the striped spots look different when receiving strong light coming from the back side in the orthogonal nicotine state. Moreover, where the Rpva deviation is deeper than 10 nm / cm, the striped spots will be sharper.

There are various means of preparing polarizers with a small stretching arrangement nonuniformity of PVA. Such means include providing a swelling step prior to the dyeing step and raising the bath temperature in the dyeing and curing step. In the dyeing and curing step, sufficient water can be supplied to the PVA film to be stretched by swelling or treating at increased temperature, so that the stretching is performed uniformly. In order to obtain uniform stretching, it is preferable that the PVA film has a water content of 40 to 75% by weight immediately before stretching. Since the increased temperature can greatly affect the optical performance of the produced polarizer, the swelling step is substantially desirable to increase the water temperature in the dyeing and curing steps.

Stretching with a fixed with or performing a stretching step by biaxial stretching is another method for obtaining a polarizer with a small stretching arrangement nonuniformity. Stretching to a fixed width is performed by holding both edges of the film with pinch guiders, cross guiders, tender clips, expander rolls, spiral rolls, and the like, to prevent the film from shrinking in the width direction. . Biaxial stretching is stretching in both the longitudinal and transverse directions, which can be performed simultaneously or continuously. The draw ratio is preferably 2 to 12 in the major axis direction, more preferably 3 to 10, and 1 to 2 in the horizontal axis direction.

The drying step is carried out by the method disclosed in JP-A-2002-86554. Preferable drying conditions are 30-100 degreeC on temperature, and 30 second-60 minutes on time. The stretched film may be heat treated, as disclosed in Japanese Patent No. 3148513, the discoloration temperature in water is 50 ° C. or higher, or as disclosed in JP-A-7-325215 and JP-A-7-325218, The film can be aged at a controlled temperature and humidity in the atmosphere.

The step of laminating on the protective film is a step in which the polarizers from the drying step are laminated on both sides of the protective film. Lamination is preferably performed by applying an adhesive, just before laminating and passing the film between a pair of rolls. In order to reduce irregularities such as grooves due to stretching, it is preferable to adjust the moisture content of the stacked polarizers. In the present invention, the moisture content is preferably adjusted to 0.1-30%.

The adhesive agent used is not specifically limited. Useful adhesives include PVA resins (including modified PVAs having acetoacetyl groups, sulfonic acid groups, carboxyl groups, oxyalkylene groups, etc.) and aqueous boron compound solutions with preferred PVA resins. The adhesive is preferably applied with a dry thickness of 0.01-5 μm, more preferably 0.05-3 μm.

In order to improve the adhesion between the polarizer and the protective film, it is preferable to hydrophilize the protective film by surface treatment before adhesion. Surface modification for hydrophilization can be achieved by known methods, for example saponification with alkaline solutions or by corona treatment. Surface treatment may be performed after providing a primer layer such as gelatin for improving adhesion. As described in JP-A-14-267839, the protective film preferably has a water contact angle of 50 ° or less.

The drying step after lamination is carried out under the conditions described in JP-A-2000-86554. Preferable conditions are 30-100 degreeC by temperature, and 30 second-60 minutes on time. Preferably, the film can be aged in the atmosphere with controlled humidity and temperature, as disclosed in JP-A-7-325220.

After all, preferably prepared polarizers have an iodine content of 0.1-3.0 g / m 2, boron content of 0.1-5.0 g / m 2, potassium content of 0.1-2.0 g / m 2, and zinc content of 0-2.0 g / m 2. . The potassium content can be up to 0.2% by weight as described in JP-A-13-166143. The zinc content can be 0.04-0.5 weight percent or less, as described in JP-A-12-35512.

The polarizer may comprise an organotitanium compound and / or an organozirconium compound, which may be added at any stage of dyeing, stretching and curing, to improve dimensional stability, as disclosed in Japanese Patent No. 3323255. Dichroic dyes may be mixed in the polarizer for color control.

Specific cellulose acylate films suitable for use as protective films are described below. Two or more different kinds of cellulose acylates may be mixed and used.

The cellulose acylate used in the present invention is a mixed fatty acid ester obtained by replacing the hydroxyl group of cellulose with an acetyl group and an acyl group having 3 or more carbon atoms. The degree of substitution of hydroxyl groups by acyl groups satisfies equations (3) and (4):

2.0≤A + B≤3.0 (3)

0 <B (4)

Wherein A and B each represent a degree of substitution of a hydroxyl group by an acyl group; More specifically, A is a degree of substitution by an acetyl group, and B is a degree of substitution by an acyl group having three or more carbon atoms.

Glucose units linked through β-1,4 overlap bind to complement each cellulose having free hydroxyl groups in 2-position, 3-position, and 6-position. Cellulose acylate is a polymer in which part or all of the hydroxyl groups are esterified with acyl groups. The degree of substitution by acyl groups is the proportion of esterified hydroxyl groups in 2-position, 3-position, and 6-position (one hundred percent esterification is substitution degree 1).

The sum of substitution degrees A and B, (A + B) is in the range of 2.0 to 3.0, preferably in the range of 2.2 to 2.9, more preferably in the range of 2.40 to 2.85, as represented by formula (3). Substitution degree B is 0 or more, Preferably it is 0.6 or more.

(A + B) less than 2.0 means that the cellulose acylate is hydrophilic and susceptible to ambient humidity. It is preferred that at least 28% of the acyl substituents having 3 or more carbon atoms are at the 6-position of the glucose unit, more preferably at least 30%, still more preferably at least 31%, and most preferably at least 32%. . The sum of degrees of substitution A and B at the 6-position of the glucose unit is preferably at least 0.75, more preferably at least 0.80, even more preferably at least 0.85.

Cellulose acylate that satisfies the conditions described above provides a film-forming solution with satisfactory solubility and filtration capacity (ie low viscosity), even in chlorine-free organic solvents.

When the cellulose acylate film is provided as a protective film on the side of the liquid crystal cell of the polarizer, the cellulose acylate preferably satisfies the formulas (5) and (6):

2.0≤DS2 + DS3≤3.0 (5)

DS6 / (DS2 + DS3 + DS6) ≥0.315 (6)

Here, DS2, DS3, and DS6 represent substitution degrees of hydroxyl groups at 2-position, 3-position, and 6-position of glucose units constituting cellulose by acyl groups, respectively.

When the formulas (5) and (6) are satisfied, the optical performance of the cellulose acylate film can be easily controlled within the desired range.

Acyl groups having three or more carbon atoms may be aliphatic groups or aromatic groups for forming alkylcarbonyl esters, alkenylcarbonyl esters, aromatic carbonyl esters, aromatic alkylcarbonyl esters, and the like. The acyl group may have a substituent. Examples of suitable acyl groups having 3 or more carbon atoms include propionyl, butanoyl, pentanoyl, hexanoyl, heptanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, Octadecanoyl, isobutanoyl, t-butanoyl, cyclohexanecarbonyl, oleoyl, benzoyl, naphthylcarbonyl, and cinnamoyl. Preferred among them are propionyl, butanoyl, dodecanoyl, octadecanoyl, t-butanoyl, oleyl, benzoyl, naphthylcarbonyl, and cinnamoyl. Especially preferred are propionyl and butanoyl. Substitution degree B with a propionyl group becomes like this. Preferably it is 1.3 or more.

Examples of cellulose mixed fatty acid esters include cellulose acetate propionate and cellulose acetate butyrate.

The basic principles for the synthesis of cellulose acylate are described in Migita, et al., Mokuzai kagaku, pp. 180-190, Kyoritsu Shuppan (1968). Liquid acetylation processes using carboxylic anhydride, acetic acid, and sulfonic acid catalysts are typical.

More specifically, cellulose such as cotton linter or wood pulp, in order to fully esterify cellulose to obtain cellulose acylate having a total substitution of almost 3.00 in 2-, 3- and 6-positions. The raw material is pretreated with an appropriate amount of acetic acid and poured into the pre-cooled carboxylated mixed solution. The carboxylated mixed solution usually contains acetic acid as a solvent, carboxylic anhydride as an esterifying agent and sulfonic acid as a catalyst. Carboxylic anhydrides are usually used in stoichiometric excess relative to the total amount of cellulose and water content as reverse reactants in the reaction system. After termination of esterification, an aqueous solution of neutralizing agent (eg carbonate, acetate or calcium, magnesium, iron, aluminum or zinc oxide) is used to hydrolyze the excess residual carboxylic anhydride and neutralize the esterification catalyst. Is added. The finished ester is thus saponified and aged by maintaining 50 ° to 90 ° C. under a small amount of an acetylation catalyst (usually residual sulfonic acid can play a role) until the desired degree of acyl substitution and neutralization is obtained. When the desired cellulose acylate is obtained, the catalyst remaining in the system cannot be fully neutralized or neutralized with the neutralizing agent described above, and the cellulose acylate solution is poured into water or dilute sulfonic acid, or the water or dilute sulfonic acid is cellulose acylate To the solution. The cellulose acylate thus separated is also obtained by washing, stabilizing or similar procedures with water to obtain the specific cellulose acylate described above.

It is preferable that the polymer component of the specific cellulose acylate film described above to be used in the present invention should be substantially made of a specific cellulose acylate. The term "substantially" as used herein means that at least 55%, preferably at least 70%, more preferably at least 80% by weight of the polymer component is a specific cellulose acylate.

Cellulose acylate is preferably used in particulate form. It is preferred that at least 90% by weight of the cellulose acylate particles used have a particle size of 0.5 to 5 mm, and at least 50% by weight of the particles to have a particle size of 1 to 4 mm. The shape of the cellulose acylate particles is preferably as spherical as possible.

The cellulose acylate preferably has a viscosity-average degree of polymerization of 200 to 700, more preferably 250 to 550, even more preferably 250 to 400, particularly preferably 250 to 350. The average degree of polymerization is Uda, et al. (Uda Kazuo and Saito Hideo, Journal of Fiber Science and Technology, Japan, Vol. 18, No. 1, pp. 105-120, 1962). Details can be found in JP-A-9-95538.

Removal of the low molecular weight component causes an increase in the average molecular weight (polymerization degree), but decreases its viscosity than the original cellulose acylate. Thus, the cellulose acylate used is advantageously free of low molecular weight components. Cellulose acylates with reduced low molecular weight components are obtained by removing the low molecular weight components from the cellulose acylates synthesized in a general synthetic method by washing with a suitable organic solvent. When producing cellulose acylates with reduced low molecular weight components, the amount of sulfonic acid catalyst used in the acetylation reaction is preferably controlled within the range of 0.5 to 25 parts by weight per 100 parts by weight of cellulose acylate. Such controlling the amount of catalyst is also beneficial in terms of uniform molecular weight distribution of the resulting cellulose acylate. The water content of the cellulose acylate is preferably 2% by weight or less, more preferably 1% by weight or less, even more preferably 0.7% by weight or less. In general, cellulose acylate has a constant moisture content, which is known as 2.5 to 5% by weight. Drying is required to achieve moisture content of 2% or less. The drying method is not limited as long as the desired moisture content is reached.

For details of the synthesis of raw cotton and cellulose acylate, see Journal of Thechnical Disclosure, No. 2001-1745, pp. 7-12, Japanese Invention and Innovation Association, March, 2001.

The cellulose acylate film usable in the present invention is obtained from a solution of the specific cellulose acylate described above in an organic solvent which may contain additives if desired.

Additives that can be added to the cellulose acylate solution include plasticizers, UV absorbers, antidegradants, retardation (optical anisotropy) enhancers, retardation (optical anisotropy) reducers, fine particles, dyes, mold release agents, and infrared absorbers. In this invention, addition of a retardation promoter is preferable. Also recommended is the addition of at least one of plasticizers, UV absorbers, dyes, and release agents.

The additive may be solid or oily. That is, it is not limited by the melting point or the boiling point. For example, a UV absorber having a melting point of 20 ° C. or lower and a UV absorber having a melting point of 20 ° C. or higher may be used in combination, or as proposed in JP-A-2001-151901, Mixtures can be used.

The UV absorbers used are freely selected according to the intended purpose among salicylic esters, benzophenones, benzotriazoles, benzoates, cyanoacrylates, nickel complex salts and the like. Preferred are benzophenone, benzotriazole, and salicylic esters. Examples of benzophenone UV absorbers include 2,4-dihydroxybenzophenone, 2-hydroxy-4-acetoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy- 4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-dodecyloxy Benzophenone, and 2-hydroxy-4- (2-hydroxy-3-methacryloxy) propoxybenzophenone. Examples of benzotriazole UV absorbers include 2- (2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-5 ' -t-butylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-t-amylphenyl) benzotriazole, 2- (2'-hydroxy-3', 5 ' -Di-t-butylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-5'-t-octylphenyl) benzotriazole. Examples of salicylic ester UV absorbers include phenyl salicylate, p-octylphenyl salicylate, and p-t-butylphenyl salicylate. Particularly preferred among the UV absorbers mentioned are 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-methoxybenzophenone, 2- (2'-hydroxy-3 ' -t-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-5'-t-butylphenyl) benzotriazole, 2- (2'-hydroxy-3 ' , 5'-di-t-amylphenyl) benzotriazole, and 2- (2'-hydroxy-3 ', 5'-di-t-butylphenyl) -5-chlorobenzotriazole.

In order to protect over a wider range of wavelengths, it is desirable to use a combination of UV absorbers having different absorption wavelengths. UV absorbers for LCD applications are required to have a high absorption at less than 370nm to prevent liquid crystal distortion and to absorb almost no visible light at 400nm or more in order to secure the display quality. In this respect, the above-described benzotriazole compound, benzophenone compound and salicylic ester are preferred. Inter alia, benzotriazole UV absorbers are particularly preferred; This is because they rarely express color in cellulose acylate films.

In addition to the above-described UV absorbers, the following publications: JP-A-60-2235852, JP-A-3-199201, JP-A-5-1907073, JP-A-5-194789, JP-A-5-271471, JP -A-6-107854, JP-A-6-118233, JP-A-6-148430, JP-A-7-11055, JP-A-7-11056, JP-A-8-29619, JP-A Also useful are the compounds described in -8-239509, and JP-A-2000-204173.

The amount of UV absorber is preferably 0.001 to 5% by weight, more preferably 0.01 to 1% by weight, based on cellulose acylate. At an amount of less than 0.001% by weight, sufficient UV absorbing effect is not obtained. In amounts above 5% by weight, a UV absorber may bleed off the film surface.

The UV absorber may be added when the cellulose acylate is dissolved in the solvent or added to the dope (cellulose acylate solution for film formation). For easy control of the absorption characteristics of the spectrum, the UV absorber is preferably mixed in the dope just before casting by a fixed mixer or the like.

Antithermal agents act to prevent cellulose acylate from degrading due to degradation. Useful antipyretic agents include butylamine, hindered amine compounds (see JP-A-8-325537), guanidine compounds (see JP-A-5-271471), benzotriazole UV absorbers (JP-A-6-235819 Reference), and a benzophenone UV absorber (see JP-A-6-118233).

Plasticizers preferably include phosphoric esters and carboxylic esters. Examples of preferred plasticizers are triphenyl phosphate, tricresyl phosphate, cresyldiphenyl phosphate, octyldiphenyl phosphate, biphenyldiphenyl phosphate, trioctyl phosphate, tributyl phosphate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, di Octyl phthalate, diphenyl phthalate, di (ethylhexyl) phthalate, triethyl O-acetylcitrate, tributyl O-acetylcitrate, acetyltriethyl citrate, acetyltributyl citrate, butyl oleate, methylacetyl ricinol Latex, dibutyl sebacate, triacetin, tributyrin, butylphthalylbutyl glycolate, ethylphthalylethyl glycolate, methylphthalylethyl glycolate, and butylphthalylbutyl glycolate. More preferred among them are (di) pentaerythritol, glycerol ester, and diglycerol ester.

Release agents include ethyl citrate and derivatives thereof. Infrared absorbers include those described in JP-A-2001-194522.

As mentioned, dyes may be added to the cellulose acylate for color control. The amount of dye added for this purpose is preferably 10 to 1000 ppm, more preferably 50 to 500 ppm, based on cellulose acylate. Such dye addition causes a reduction in light piping and yellowness of the cellulose acylate film. The dye may be added to the solvent with cellulose acylate in the preparation of cellulose acylate solution (dope) or at any other stage of dope preparation or after dope preparation. The dye may be added to the UV absorber to be added inline.

The dyes preferably used in the present invention for color control are represented by the formula (I) or (II):

Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , and R ⁸ each represent a hydrogen atom, a hydroxyl group, an aliphatic group, an aromatic group, a heterocycle group, a halogen atom, a cyano group, and nitro , COR ⁹ , COOR ⁹ , NR ⁹ R ¹⁰ , NR ¹⁰ COR ¹¹ , NR ¹⁰ SO ₂ R ¹¹ , CONR ⁹ R ¹⁰ , SO ₂ NR ⁹ R ¹⁰ , COR ¹¹ , SO ₂ R ¹¹ , OCOR ¹¹ , NR ⁹ CONR ¹⁰ R ¹¹ , CONHSO ₂ R ¹¹ or SO ₂ NHCOR ¹¹ ; R ⁹ And R ¹⁰ each represents a hydrogen atom, an aliphatic group, an aromatic group or a heterocycle group; R ¹¹ represents an aliphatic group, an aromatic group or a heterocycle group; R ⁹ and R ¹⁰ may be linked to each other to form a 5- or 6-membered ring; And R ¹ And the combination of R ² in combination or R ² and R ³ of the can to form a ring.

Wherein R ²¹ , R ²³ , and R ²⁴ each represent a hydrogen atom, a hydroxyl group, a nitro group, a cyano group, an aliphatic group, an aromatic group, COR ²⁹ , COOR ²⁹ , NR ²⁹ R ³⁰ , NR ³⁰ COR ³¹ Or NR ³⁰ SO ₂ R ³¹ ; R ²² represents an aliphatic group or an aromatic group; R ²⁰ And R ³⁰ each have the same meaning as R ⁹ and R ¹⁰ in formula (I); And R ³¹ has the same meaning as R ¹¹ in formula (I); At least one of R ²¹ , R ²² , R ²³ , and R ²⁴ is a condition that is a substituent (not a hydrogen atom).

In formula (I), the aliphatic group represented by R ¹ to R ¹¹ is an alkyl group having 1 to 20 carbon atoms (eg, methyl, ethyl, n-butyl, isopropyl, 2-ethylhexyl, n-decyl or n-octadecyl), a cycloalkyl group having 1 to 20 carbon atoms (eg, cyclopentyl or cyclohexyl), and an allyl group, each of which may have a substituent. Substituents include halogen atoms (e.g., F, Cl, Br or I), hydroxyl groups, cyano groups, nitro groups, carboxyl groups, aryl groups having 6 to 10 carbon atoms (e.g., phenyl or naphthyl), 20 Amino groups having up to carbon atoms (eg, NH ₂ , NHCH ₃ , N (C ₂ H ₅ ) ₂ , N (C ₄ H ₉ ) ₂ , N (C ₈ H ₁₇ ) ₂ , anilino or 4- Methoxyanilino), an amide group having 1 to 20 carbon atoms (for example, acetylamino, hexanoylamino, benzoylamino or octadecanoylamino), a carbamoyl group having 1 to 20 carbon atoms (for example, Unsubstituted carbamoyl, methylcarbamoyl, ethylcarbamoyl, octylcarbamoyl or hexadecylcarbamoyl), ester groups having 2 to 20 carbon atoms (e.g., methoxycarbonyl, ethoxycarbyl) Carbonyl, phenoxycarbonyl, n-butoxycarbonyl or dodecyloxycarbonyl), alkoxy with up to 20 carbon atoms Or an aryloxy group (for example, methoxy, ethoxy, butoxy, isopropoxy, benzyloxy, phenoxy or octadecyloxy), a sulfonamide group having 1 to 20 carbon atoms (for example, methanesulfone Amide, ethanesulfonamide, butanesulfonamide, benzenesulfonamide or octasulfonamide), sulfamoyl groups having 0 to 20 carbon atoms (e.g., unsubstituted sulfamoyl, methyl sulfamoyl, butyl sulfamoyl or decyl sulfamoyl) And 5- or 6-membered heterocycle groups (eg, pyridyl, pyrazolyl, morpholino, piperidino, pyrrolino or benzoxazolyl).

The aromatic group represented by R ¹ to R ¹¹ includes a substituted or unsubstituted aryl group (eg, phenyl or naphthyl) having 6 to 10 carbon atoms. Substituents for aryl groups include those cited above as substituents for aliphatic groups, furthermore alkyl groups having 1 to 20 carbon atoms (eg, methyl, ethyl, butyl, t-butyl or octyl).

The heterocycle groups represented by R ¹ to R ¹¹ are substituted or unsubstituted 5- or 6-membered heterocycle groups (for example, pyridine, piperidine, morpholine, pyrrolidine, pyrazole, pyrazolidone, pyra Sleepy, pyrazolone or benzoxazole). Substituents for heterocycle groups include those mentioned above as substituents for aromatic groups.

5- or 6-membered rings formed by the bonding of R ⁹ and R ¹⁰ include morpholine rings, piperidine rings, and pyrrolidine rings. The ring formed by the bond of R ¹ and R ² or the bond of R ² and R ³ is preferably a five-membered or six-membered ring (eg benzene ring or phthalimide ring).

In formula (II), R ²¹ To aliphatic groups represented by R ²⁴ have the same meanings as the aliphatic groups represented by R ¹ to R ¹¹ in formula (I), and R ²¹ To aromatic group represented by R ²⁴ has the same meaning as the aromatic group represented by R ¹ to R ¹¹ in formula (I).

The aforementioned additives may be added at any stage in the preparation of the dope. The addition of the additive may be provided separately as the last step in the dope preparation. The amount of each additive added is not limited as long as the intended effect is exhibited. The cellulose acylate protective film has a multilayer structure, and the type and amount of the additive may be different among the sublayers. The choice of the type and amount of additive in the cellulose acylate film is, for example, well known in the art described in JP-A-2001-151902. In terms of suitability for polarizer processing and LCD assembly, the glass transition point Tg of the cellulose acylate film is 70-150 ° C., as measured by the dynamic viscoelasticity measuring device Vibron DVA-225 manufactured by ITK Co., Ltd. It is preferable to select the type and amount of the additive to be preferably 80 ~ 135 ℃.

For additional information on additives of cellulose acylate films, see Journal of Technical Disclosure, No 2001-1745, p. 16 et seq., From the Japanese Association of Invention and Innovation, March, 2001.

In the present invention, retardation enhancers are particularly preferred for improving large optical anisotropy in order to obtain the desired retardation value.

Retardation enhancers include rod-shaped or discotic compounds. Rod or discotic compounds include compounds having two or more aromatic rings.

As the retardation enhancer, the rod-shaped compound is added in an amount of preferably 0.1 to 30 parts by weight, more preferably 0.5 to 20 parts by weight per 100 parts by weight of the total polymer component including cellulose acylate. The discotic compound as the retardation enhancer is preferably 0.05 to 30 parts by weight, more preferably 0.1 to 20 parts by weight, even more preferably 0.2 to 15 parts by weight, per 100 parts by weight of the total polymer component including cellulose acylate, Especially preferably, it is added in the quantity of 0.5-10 weight part.

Discotic compounds are superior to rod-shaped compounds in enhancing retardation Rth and are preferably used where very high Rth is required. Two or more retardation enhancers can be used in combination.

As the retardation enhancer, it is preferable that the rod-shaped or discotic compound shows the maximum absorption in the wavelength region of 250 to 400 nm and does not show the absorption substantially in the visible region.

Discotic compounds having two or more aromatic rings are described in detail. The term "aromatic ring" as used herein includes aromatic heterocycle rings as well as aromatic hydrocarbon rings.

The aromatic hydrocarbon ring is preferably a six-membered ring, ie a benzene ring.

Aromatic heterocycle rings are usually unsaturated heterocycle rings. Aromatic heterocycle rings are preferably 5- to 7-membered rings, preferably 5- or 6-membered rings. Aromatic heterocycle rings usually have the most double bonds. Heteroatoms preferably include nitrogen, oxygen, and sulfur, with nitrogen being particularly preferred. Examples of aromatic heterocycle rings include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring , Pyran ring, pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, and 1,3,5-triazine ring.

The aromatic ring is preferably a benzene ring, furan ring, thiophene ring, pyrrole ring, oxazole ring, thiazole ring, imidazole ring, triazole ring, pyridine ring, pyrimidine ring, pyrazine ring, and 1,3,5 -Triazine ring. 1,3,5-triazine ring is particularly preferred. Specific examples of preferred discotic compounds are provided, for example, in JP-A-2001-166144.

The number of aromatic rings contained in the discotic compound is preferably 2-20, more preferably 2-12, even more preferably 2-8, particularly preferably 2-6. The mode of connection between the two aromatic rings can be any of (a) fusion (to form a fused ring), (b) through a single bond, and (c) through a linking group. As aromatic, the rings do not form spiro bonding.

The fused ring (two or more aromatic rings fused together) includes indene ring, naphthalene ring, azulene ring, fluorene ring, phenanthrene ring, anthracene ring, asenanaphthalene ring, biphenylene ring, naphthacene ring, pyrene ring, Indole ring, isoindole ring, benzene furan ring, benzothiophene ring, indolizine ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring, purine ring, indazole ring, chromen ring , Quinoline ring, isoquinoline ring, quinolidine ring, quinazoline ring, cinnoline ring, quinoxaline ring, phthalazine ring, pteridine ring, carbazole ring, acridine ring, phenanthridine ring, x Acidene ring, phenazine ring, phenothiazine ring, phenoxatiin ring, phenoxazine ring, and thianthrene ring. Preferred among them are naphthalene ring, azulene ring, indole ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring, and quinoline ring.

In bond mode (b) the single bond is preferably a bond between the carbon atoms of two aromatic rings. Two aromatic rings may be linked through two or more single bonds to form an aliphatic ring or a non-aromatic ring between them.

The linking group in the bonding mode (c) is preferably between the carbon atoms of the two aromatic rings. Linking groups preferably include alkylene groups, alkenylene groups, alkynylene groups, -CO-, -O-, -NH-, -S-, and combinations thereof. Examples of linking group combinations are shown below. The order of the unit linkers can be reversed.

c1: -CO-O-

c2: -CO-NH-

c3: -alkylene-O-

c4: -NH-CO-NH-

c5: -NH-CO-O-

c6: -O-CO-O-

c7: -O-alkylene-O-

C8: -CO-alkenylene-

C9: -CO-alkenylene-NH-

c10: -CO-alkenylene-O-

c11: -alkylene-CO-O-alkylene-O-CO-alkylene-

c12: -O-alkylene-CO-O-alkylene-O-CO-alkylene-O-

c13: -O-CO-alkylene-CO-O-

c14: -NH-CO-alkenylene-

c15: -O-CO-alkenylene-

Aromatic rings and linking groups may have substituents. Substituents include halogen atoms (e.g., F, Cl, Br or I), hydroxyl groups, carboxyl groups, cyano groups, amino groups, nitro groups, sulfo groups, carbamoyl groups, sulfamoyl groups, ureido groups, alkyl groups, alkenyl groups, Alkynyl group, aliphatic acyl group, aliphatic acyloxy group, alkoxy group, alkoxycarbonyl group, alkoxycarbonylamino group, alkylthio group, alkylsulfonyl group, aliphatic amide group, aliphatic sulfonamide group, aliphatic substituted amino group, aliphatic substituted carbamoyl group, Aliphatic substituted sulfamoyl groups, aliphatic substituted ureido groups, and non-aromatic heterocycle groups.

The alkyl group preferably contains 1 to 8 carbon atoms. Acyclic alkyl groups are preferred over cyclic alkyl groups, and straight chain alkyl groups are preferred over branched alkyl groups. Alkyl groups may have substituents (eg, hydroxyl, carboxyl, alkoxy or alkyl amino). Examples of substituted or unsubstituted alkyl groups are methyl, ethyl, n-butyl, n-hexyl, 2-hydroxyethyl, 4-carboxybutyl, 2-methoxyethyl, and 2-diethylaminoethyl.

Alkenyl groups preferably contain 2 to 8 carbon atoms. Bicyclic alkenyl groups are preferred to cyclic alkenyl groups, and straight chain alkenyl groups are preferred to branched forms. Alkenyl groups may have substituents. Examples of alkenyl groups are vinyl, allyl, and 1-hexenyl.

Alkynyl groups preferably contain 2 to 8 carbon atoms. Bicyclic alkynyl groups are preferred over cycle groups. The linear alkynyl group is more preferable than the branched alkynyl group. Alkynyl groups may have a substituent. Examples of alkynyl groups are ethynyl, 1-butynyl, and 1-hexynyl.

Aliphatic acyl groups preferably have 1 to 10 carbon atoms. Examples of fatty acyl groups include acetyl, propanoyl, and butanoyl.

Fatty acyloxy groups preferably contain 1 to 10 carbon atoms. Examples of fatty acyloxy include acetoxy.

The alkoxy group preferably contains 1 to 8 carbon atoms. The alkoxy group may have a substituent (eg, an alkoxy group). Examples of substituted or unsubstituted alkoxy groups are methoxy, ethoxy, butoxy, and methoxyethoxy.

Alkoxycarbonyl groups preferably contain 2 to 10 carbon atoms. Examples of alkoxycarbonyl groups include methoxycarbonyl and ethoxycarbonyl.

The alkoxycarbonylamino group preferably contains 2 to 10 carbon atoms. Alkoxycarbonylamino groups include methoxycarbonylamino and ethoxycarbonylamino.

The alkylthio group preferably contains 1 to 12 carbon atoms. Examples of alkylthio groups are methylthio, ethylthio, and octylthio.

The alkylsulfonyl group preferably contains 1 to 8 carbon atoms. Examples of alkylsulfonyl groups are methanesulfonyl and ethanesulfonyl.

Aliphatic amide groups preferably contain 1 to 10 carbon atoms. Examples include acetamide.

Aliphatic sulfonamide groups preferably contain from 1 to 8 carbon atoms. Examples include methanesulfonamide, butanesulfonamide, and n-octanesulfonamide.

Aliphatic substituted amino groups preferably contain from 1 to 10 carbon atoms. Aliphatic substituted amino groups include dimethylamino, diethylamino, and 2-carboxyethylamino.

Aliphatic substituted carbamoyl groups preferably contain 2 to 10 carbon atoms. Examples are methylcarbamoyl and diethylcarbamoyl.

The aliphatic substituted sulfamoyl group preferably contains 1 to 8 carbon atoms. Examples include methylsulfamoyl and diethylsulfamoyl.

Aliphatic substituted ureido groups preferably contain 2 to 10 carbon atoms. Examples include methylureido.

Non-aromatic heterocycle groups include piperidino and morpholino.

As a retardation enhancer, the discotic compound preferably has a molecular weight of 300 to 800.

Rod-shaped compounds preferably usable as retardation enhancers are compounds having a linear molecular structure. To have a "straight molecular structure" means a compound having a straight molecular structure when in the thermodynamic most stable state. The most thermodynamically stable structures can be obtained through crystal structure analysis or molecular orbital estimation. For example, molecular orbital estimation is performed with molecular orbital estimation software (eg, WinMOPAC 2000 manufactured by Fujitsu Ltd.) in order to obtain the molecular structure with the lowest formation heat. Having a "straight molecular structure" indicates that the molecular backbone forms an angle of at least 140 ° in the thermodynamic most stable state as measured.

Preferably, the rod-shaped compound having two or more aromatic rings includes those represented by formula (III):

Ar ¹ -L ¹ -Ar ² (III)

Where Ar ¹ and Ar ² Each represents an aromatic group; And L ¹ is a divalent linking group.

In the formula (III), the term "aromatic group" includes an aryl group (aromatic hydrocarbon group), a substituted aryl group, an aromatic heterocycle group, and a substituted aromatic heterocycle group. Substituted or unsubstituted aryl groups are preferred to substituted or unsubstituted aromatic heterocycle groups. Aromatic heterocycle rings are usually unsaturated. Aromatic heterocycle rings are preferably 5- or 7-membered rings, more preferably 5- or 6-membered rings. Aromatic heterocycle rings usually have a large number of double bonds. Heteroatoms preferably include nitrogen, oxygen and sulfur atoms. More preferred are nitrogen atoms or sulfur atoms.

Aromatic rings of aromatic groups include benzene ring, furan ring, thiophene ring, pyrrole ring, oxazole ring, thiazole ring, imidazole ring, triazole ring, pyridine ring, pyrimidine ring, and pyrazine ring Rings are particularly preferred.

Substituents of substituted aryl groups and substituted aromatic heterocycle groups include halogen atoms (e.g., F, Cl, Br or I), hydroxyl groups, carboxyl groups, cyano groups, amino groups, alkylamino groups (e.g., methylamino, ethyl Amino, butylamino, dimethylamino), nitro group, sulfo group, carbamoyl group, alkylcarbamoyl group (e.g., N-methylcarbamoyl, N-ethylcarbamoyl or N, N-dimethylcarbamoyl) ), Sulfamoyl groups, alkylsulfamoyl groups (e.g., N-methylsulfamoyl, N-ethylsulfamoyl or N, N-dimethylsulfamoyl), ureido groups, alkylureido groups (e.g., N-methyl Ureido, N, N-dimethylureido or N, N, N'-trimethylureido), alkyl groups (e.g., methyl, ethyl, propyl, butyl, pentyl, heptyl, octyl, isopropyl, sec-butyl, t-amyl, cyclohexyl or cyclopentyl), alkenyl groups (e.g. vinyl, allyl or hexenyl), alkynyl groups (e.g. For example, ethynyl, butynyl), acyl groups (eg formyl, acetyl, butyryl, hexanoyl or lauryl), acyloxy groups (eg, acetoxy, butyryloxy, hexanoyl) Oxy or lauryloxy), alkoxy groups (e.g. methoxy, ethoxy, propoxy, butoxy, pentyloxy, heptyloxy or octyloxy), aryloxy groups (e.g. phenoxy), alkoxycarbonyl groups (Eg, methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, butoxycarbonyl, pentyloxycarbonyl or heptyloxycarbonyl), aryloxycarbonyl groups (eg phenoxycarbonyl), Alkoxycarbonylamino groups (eg butoxycarbonylamino or hexyloxycarbonylamino), alkylthio groups (eg methylthio, ethylthio, propylthio, butylthio, pentylthio, heptylthio or octyl Thio), arylthio group (e.g., phenylthio), alkylsulfonyl group (e.g., For example, methylsulfonyl, ethylsulfonyl, propylsulfonyl, butylsulfonyl, pentylsulfonyl, heptylsulfonyl or octylsulfonyl), amide groups (e.g. acetamide, butylamide, hexylamide or lauryl) Amides), and non-aromatic heterocycle groups (eg, morphoryl or pyrazinyl).

Substituents of a substituted aryl group and a substituted aromatic heterocycle group are preferably a halogen atom, cyano group, carboxyl group, hydroxyl group, amino group, alkylamino group, acyl group, acyloxy group, amide group, alkoxycarbonyl group, alkoxy group, alkylthio group And alkyl groups.

The alkyl group and alkyl moiety of the alkylamino, alkoxycarbonyl, alkoxy and alkylthio groups may have a substituent. Examples of the substituent of the alkyl group or alkyl moiety include a halogen atom, hydroxyl group, carboxyl group, cyano group, amino group, alkylamino group, nitro group, sulfo group, carbamoyl group, alkylcarbamoyl group, sulfamoyl group, alkylsulfayl group, urea Ido group, alkylureido group, alkenyl group, alkynyl group, acyl group, acyloxy group, acylamino group, alkoxy group, aryloxy group, alkoxycarbonyl group, aryloxycarbonyl group, alkoxycarbonylamino group, alkylthio group, arylthio group, Alkylsulfonyl groups, amide groups, and non-aromatic heterocycle groups. Preferred among these substituents are halogen atom, hydroxyl group, amino group, alkylamino group, acyl group, acyloxy group, acylamino group, alkoxycarbonyl group, and alkoxy group.

In formula (III), the divalent linking group represented by L ¹ is selected from alkylene group, alkenylene group, alkynylene group, -O-, -CO-, and combinations thereof.

The alkylene group may have a cycle structure. The cycle alkylene group is preferably a cyclohexylene group, more preferably a 1,4-cyclohexylene group. Straight chain bicyclic alkylene groups are preferred to branched bicyclic alkylene groups. The alkylene group is preferably 1 to 20 carbon atoms, more preferably 1 to 15 carbon atoms, still more preferably 1 to 10 carbon atoms, particularly preferably 1 to 8 carbon atoms, particularly preferably It contains 1 to 6 carbon atoms.

Alkenylene groups and alkynylene groups preferably have a bicyclic structure. The linear bicyclic structure is more preferable than the branched bicyclic structure. Alkenylene groups and alkynylene groups are preferably 2 to 10 carbon atoms, more preferably 2 to 8 carbon atoms, even more preferably 2 to 6 carbon atoms, particularly preferably 2 to 4 carbon atoms Most preferably two carbon atoms (ie, vinylene or ethynylene).

The arylene group preferably contains 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, even more preferably 6 to 12 carbon atoms.

In the molecular structure of formula (III), Ar ¹ and Ar ² preferably form an angle of at least 140 ° at L ¹ .

Rod compounds are Mol. Crysta. Liq. Cryst., Vol. 53, p. 229 (1979), ib., Vol. 89, p. 93 (1982), ib., Vol. 145, p. 111 (1987), ib., Vol. 170, p. 43 (1989), J. Am. Chem., Vol. 40, p. 420 (1975), and Tetrahedron, vol. 48, No. 16, p. 343 (1992), such as those described in the publications.

 Among the rod-like compounds of formula (III), those represented by formula (IV) are preferred:

Wherein R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁹ , and R ¹⁰ each represent a hydrogen atom or a substituent; R ¹ , R ² , R ³ , R ⁴ , and R ⁵ At least one of represents an electron donating group; R ⁸ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, 6 An aryloxy group having ˜12 carbon atoms, an alkoxycarbonyl group having 2 to 12 carbon atoms, an acylamino group having 2 to 12 carbon atoms, a cyano group or a halogen atom.

In formula (IV), the substituents represented by R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁹ , and R ¹⁰ include a group of substituents T to be described later.

R ¹ , R ² , R ³ , R ⁴ , and R ⁵ At least one of which represents an electronic provider. Preferably R ¹ , R ³ , and R ⁵ At least one of is an electron provider. More preferably R ³ is an electron donor group. The electron donor is a group having a Hammett substitution constant sigma p or less. Chem. Rev., vol. 91, p. 165 (1991) describes an electron electron providing group having a sigma p value of 0 or less. It is more preferable to have sigma p of -0.85-0, such as an alkyl group, an alkoxy group, an amino group, and a hydroxyl group. The electron donor group preferably comprises an alkyl group and alkoxy, more preferably an alkoxy group (preferably between 1 and 12 carbon atoms, more preferably between 1 and 8 carbon atoms, even more preferably between 1 and 6 carbon atoms , More preferably 1 to 4 carbon atoms).

R ¹ preferably represents a hydrogen atom or an electron donor group, more preferably an alkyl group, an alkoxy group, an amino group or a hydroxyl group, even more preferably an alkyl group having 1 to 4 carbon atoms and a 1 to 12 carbon atoms Alkoxy groups, particularly preferably alkoxy groups (preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, even more preferably 1 to 6 carbon atoms, particularly preferably 1 to 4 carbon atoms Atoms, most preferably a methoxy group.

R ² preferably has a hydrogen atom, an alkyl group, an alkoxy group, an amino group or a hydroxyl group, more preferably a hydrogen atom, an alkyl group or an alkoxy group, even more preferably a hydrogen atom, an alkyl group (preferably having 1 to 4 carbon atoms, More preferably has a methyl group or an alkoxy group (preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, even more preferably 1 to 6 carbon atoms, particularly preferably 1 to 4 carbon atoms) Including carbon atoms). In particular, preferably R ² is a hydrogen atom, a methyl group or a methoxy group.

R ³ preferably represents a hydrogen atom or an electron donor group, more preferably a hydrogen atom, an alkyl group, an alkoxy group, an amino group or a hydroxyl group, even more preferably an alkyl group and an alkoxy group, particularly preferably an alkoxy group (preferably 1 to 1). Twelve carbon atoms, more preferably 1 to 8 carbon atoms, still more preferably 1 to 6 carbon atoms, and particularly preferably 1 to 4 carbon atoms). In particular, preferably R ³ represents an n-propoxy group, an ethoxy group or a methoxy group.

R ⁴ preferably represents a hydrogen atom or an electron donor group, more preferably a hydrogen atom, an alkyl group, an alkoxy group, an amino group or a hydroxyl group, even more preferably a hydrogen atom, an alkyl group having 1 to 4 carbon atoms or 1 to Alkoxy groups having 12 carbon atoms (preferably 1-8 carbon atoms, more preferably 1-6 carbon atoms, even more preferably 1-4 carbon atoms), particularly preferably hydrogen atoms, 1-4 An alkyl group having a carbon atom or an alkoxy group having 1 to 4 carbon atoms is represented. Especially preferably, R ⁴ represents a hydrogen atom, a methyl group or a methoxy group.

R ⁵ preferably has a hydrogen atom, an alkyl group, an alkoxy group, an amino group or a hydroxyl group, more preferably a hydrogen atom, an alkyl group or an alkoxy group, even more preferably a hydrogen atom, an alkyl group (preferably having 1 to 4 carbon atoms, More preferably has a methyl group or an alkoxy group (preferably 1 to 12 carbon atoms, more preferably 1 to 8 carbon atoms, even more preferably 1 to 6 carbon atoms, particularly preferably 1 to 4 carbon atoms) Carbon atoms), particularly preferably a hydrogen atom, a methyl group or a methoxy group.

R ⁶ , R ⁷ , R ⁹ , and R ¹⁰ are each preferably a hydrogen atom, an alkyl group having 1 to 12 carbon atoms, an alkoxy group or halogen atom having 1 to 12 carbon atoms, more preferably a hydrogen atom or a halogen Atoms, even more preferably hydrogen atoms.

R ⁸ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, 6 An aryloxy group having ˜12 carbon atoms, an alkoxycarbonyl group having 2 to 12 carbon atoms, an acylamino group having 2 to 12 carbon atoms, a cyano group or a halogen atom, each of which may have a substituent have. Substituents include the substituent T mentioned later.

R ⁸ is preferably an alkyl group having 1 to 4 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms or 2 to Aryloxy groups having 12 carbon atoms, even more preferably aryl groups having 6 to 12 carbon atoms, alkoxy groups having 1 to 12 carbon atoms or aryloxy groups having 6 to 12 carbon atoms, even more Alkoxy groups preferably having 1 to 12 carbon atoms (preferably 1 to 8 carbon atoms, more preferably 1 to 6 carbon atoms, even more preferably 1 4 carbon atoms), particularly preferably methoxy groups, to Oxy, n-propoxy group, isopropoxy group or n-butoxy group.

Among the compounds of formula (IV), those represented by formula (IV-A) are preferred:

Wherein R ¹¹ represents an alkyl group; R ¹ , R ² , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁹ , and R ¹⁰ each represent a hydrogen atom or a substituent; R ⁸ is a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, 6 An aryloxy group having ˜12 carbon atoms, an alkoxycarbonyl group having 2 to 12 carbon atoms, an acylamino group having 2 to 12 carbon atoms, a cyano group, or a halogen atom.

In formula (IV-A), R ¹ , R ² , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁹ , and R ¹⁰ Each has the same meaning as in formula (IV), and its preferred range is also the same as in formula (IV).

The alkyl group represented by R ¹¹ is preferably an alkyl group having 1 to 12 carbon atoms, which may be linear or branched, and may have a substituent. R ¹¹ preferably represents an alkyl group having 1 to 8 carbon atoms, more preferably an alkyl group having 1 to 6 carbon atoms, and even more preferably an alkyl group having 1 to 4 carbon atoms, for example, Methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl or t-butyl.

Among the compounds represented by formula (IV), those represented by formula (IV-B) are more preferred:

Wherein R ¹ , R ² , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁹ , and R ¹⁰ each represent a hydrogen atom or a substituent; R ¹¹ represents an alkyl group having 1 to 12 carbon atoms; And X is an alkyl group having 1 to 4 carbon atoms, an alkynyl group having 2 to 6 carbon atoms, an aryl group having 6 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, 6 to 12 carbon atoms Aryloxy group having a carbon atom, alkoxycarbonyl group having 2 to 12 carbon atoms, acylamino group having 2 to 12 carbon atoms, cyano group or halogen atom.

In formula (IV-B), R ¹ , R ² , R ⁴ , R ⁵ , R ⁶ , R ⁷ , R ⁹ , and R ¹⁰ Each has the same meaning as in formula (IV), and its preferred range is also the same as in formula (IV).

R ¹¹ has the same meaning as in formula (IV-A), and its preferred range is also the same as in formula (IV-A).

Wherein R ¹ , R ² , R ⁴ , and R ⁵ Each represents a hydrogen atom, X preferably represents an alkyl group, an alkynyl group, an aryl group, an alkoxy group or an aryloxy group, more preferably an aryl group, an alkoxy group or an aryloxy group, even more preferably an alkoxy group (preferably 1 to Twelve carbon atoms, more preferably 1 to 8 carbon atoms, even more preferably 1 to 6 carbon atoms, particularly preferably 1 to 4 carbon atoms), in particular a methoxy group, an ethoxy group, n -Propoxy group, isopropoxy group or n-butoxy group.

Wherein R ¹ , R ² , R ⁴ , and R ⁵ At least one of which represents a substituent, X preferably represents an alkynyl group, an aryl group, an alkoxycarbonyl group or a cyano group, more preferably an aryl group (preferably having 6 to 12 carbon atoms), a cyano group or an alkoxycarbonyl group (preferably Having 2 to 12 carbon atoms), even more preferably an aryl group (preferably having 6 to 12 carbon atoms, more preferably having a phenyl group, p-cyanophenyl group or p-methoxyphenyl group), alkoxycarbonyl group (Preferably has 2 to 12 carbon atoms, more preferably 2 to 6 carbon atoms, even more preferably 2 to 4 carbon atoms, particularly preferably methoxycarbonyl, ethoxycarbonyl Or n-propoxycarbonyl) or a cyano group, particularly preferably a phenyl group, methoxycarbonyl group, ethoxycarbonyl group, n-propoxycarbonyl group or cyano group.

Among the compounds represented by formula (IV), those represented by formula (IV-C) are even more preferred:

Wherein R ¹ , R ² , R ⁴ , R ⁵ , R ¹¹ , and X are defined for Formula (IV-B). Preferred ranges of R ¹ , R ² , R ⁴ , R ⁵ , R ¹¹ , and X are as described above.

Among the compounds represented by formula (IV), those represented by formula (IV-D) are particularly preferred:

Wherein R ² , R ⁴ , and R ⁵ are defined for formula (IV-C); R ²¹ and R ²² each represent an alkyl group having 1 to 4 carbon atoms: and X ¹ represents an aryl group having 6 to 12 carbon atoms, an alkoxycarbonyl group or cyano group having 2 to 12 carbon atoms.

In formula (IV-D), the preferable ranges of R ² , R ⁴ , and R ⁵ are the same as those described above. R ²¹ preferably represents an alkyl group having 1 to 3 carbon atoms, more preferably an ethyl group or a methyl group. R ²² preferably represents an alkyl group having 1 to 3 carbon atoms, more preferably an ethyl group or a methyl group, even more preferably a methyl group.

X ¹ is preferably an aryl group having 6 to 12 carbon atoms, an alkoxycarbonyl group or cyano group having 2 to 6 carbon atoms, more preferably a phenyl group, p-cyanophenyl group, p-methoxyphenyl group, methoxycarbonyl group , Ethoxycarbonyl group, n-propoxycarbonyl group or cyano group, even more preferably phenyl group, methoxycarbonyl group, ethoxycarbonyl group, n-propoxycarbonyl group or cyano group.

Among the compounds represented by formula (IV), those represented by formula (IV-E) are particularly preferred:

Wherein R ² , R ⁴ and R ⁵ are as defined above under the condition that at least one of them is a -OR ¹³ group wherein R ¹³ represents an alkyl group having from 1 to 4 carbon atoms; And R ²¹ , R ²² and X ¹ are also defined above.

Preferred ranges of R ² , R ⁴ and R ⁵ are the same as described above. Preferably R ⁴ and R ⁵ All represent -OR ¹³ . More preferably R ⁴ represents -OR ¹³ . R ¹³ is preferably an alkyl group having 1 to 3 carbon atoms, more preferably methyl or ethyl, even more preferably methyl.

The substituent T mentioned above has an alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, even more preferably 1 to 8 carbon atoms, for example methyl, Ethyl, isopropyl, t-butyl, n-octyl, n-decyl, n-hexadecyl, cyclopropyl, cyclopentyl or cyclohexyl), alkenyl groups (preferably 2-20 carbon atoms, more preferably 2 ~) 12 carbon atoms, even more preferably 2-8 carbon atoms, for example vinyl, allyl, 2-butenyl or 3-pentenyl, an alkynyl group (preferably 2-20 carbon atoms) More preferably 2 to 12 carbon atoms, even more preferably 2 to 8 carbon atoms, for example having propargyl or 3-pentynyl, an aryl group (preferably 6 to 30) More preferably 6 to 20 carbon atoms, still more preferably 6 to 12 carbon atoms More preferably, for example, having phenyl, p-methylphenyl or naphthyl, a substituted or unsubstituted amino group (preferably up to 20 carbon atoms, more preferably up to 10 carbon atoms) Up to 6 carbon atoms, for example amino, methylamino, dimethylamino, diethylamino or dibenzylamino), an alkoxy group (preferably 1-20 carbon atoms, more preferably 1-12) Carbon atoms, more preferably 1-8 carbon atoms, for example, methoxy, ethoxy or butoxy), an aryloxy group (preferably 6-20 carbon atoms, more preferably 6 to 16 carbon atoms, more preferably 6 to 12 carbon atoms, for example phenyloxy or 2-naphthyloxy, an acyl group (preferably 1 to 20 carbon atoms, more Preferably from 1 to 16 carbon atoms, even more preferably from 1 to 12 carbon atoms Atoms with, for example, acetyl, benzoyl, formyl or pivaloyl, alkoxycarbonyl groups (preferably 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, even more preferably 2 12 carbon atoms, for example, having methoxycarbonyl or ethoxycarbonyl, an aryloxycarbonyl group (preferably 7-20 carbon atoms, more preferably 7-16 carbon atoms, More preferably having 7 to 10 carbon atoms, for example phenyloxycarbonyl, an acyloxy group (preferably 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms) More preferably 2 to 10 carbon atoms, for example acetoxy or benzoyloxy, acylamino group (preferably 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms) To make 2 to 10 carbon atoms, for example, Amino or benzoylamino), alkoxycarbonylamino group (preferably 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, even more preferably 2 to 12 carbon atoms, for example, Methoxycarbonylamino), aryloxycarbonyl groups (preferably between 7 and 20 carbon atoms, more preferably between 7 and 16 carbon atoms, even more preferably between 7 and 12 carbon atoms, for example , Phenyloxycarbonylamino), sulfonylamino group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, even more preferably 1 to 12 carbon atoms, for example Methanesulfonylamino or benzenesulfonylamino), sulfamoyl groups (preferably up to 20 carbon atoms, more preferably up to 16 carbon atoms, even more preferably up to 12 carbon atoms, eg For example, sulfamoyl, methylsulfa Moyl, dimethylsulfamoyl or phenylsulfamoyl), carbamoyl groups (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, even more preferably 1 to 12 carbon atoms, For example, having carbamoyl, methylcarbamoyl, diethylcarbamoyl or phenylcarbamoyl, an alkylthio group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms) More preferably 1 to 12 carbon atoms, for example, methylthio or ethylthio, an arylthio group (preferably 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms) More preferably 6 to 12 carbon atoms, for example, phenylthio), a sulfonyl group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, even more preferably Having 1 to 12 carbon atoms, for example mesyl or tosyl), Neyl group (preferably having 1-20 carbon atoms, more preferably 1-16 carbon atoms, even more preferably 1-12 carbon atoms, for example methanesulfinyl, benzenesulfinyl), Ureido groups (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, even more preferably 1 to 12 carbon atoms, for example ureido, methylureido or phenylureido Phosphoric amide group (preferably 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, even more preferably 1 to 12 carbon atoms, for example, diethylphosphoric Amide or phenylphosphoric amide), hydroxyl groups, mercapto groups, halogen atoms (e.g., F, Cl, Br or I), cyano groups, sulfo groups, carboxyl groups, nitro groups, hydroxamic acid groups, Sulfino group, hydrazino group, imino group, heterocycle group (hetero atom And a nitrogen atom, an oxygen atom, a sulfur atom and the like, preferably 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, for example, imidazolyl, pyridyl, quinolyl, furyl , Piperidyl, morpholino, benzoxazolyl, benzimidazolyl or benzothiazolyl), and silyl groups (preferably from 3 to 40 carbon atoms, more preferably from 3 to 30 carbon atoms, More preferably 3 to 24 carbon atoms, for example having trimethylsilyl or triphenylsilyl. These substituents may be substituted.

When there are two or more substituents, they are the same or different and, if necessary, may be linked to each other to form a ring.

Specific examples of the rod-shaped compound represented by formula (IV) include, but are not limited to the following.

Compounds of formula (IV) can be synthesized by any mode of esterification reaction between substituted benzoic acid and phenol derivatives. For example, substituted benzoic acid is condensed to phenol and converted to acid halides, or substituted benzoic acid and phenol derivatives are condensed by dehydration with a condenser or catalyst. The foregoing procedure is preferred for manufacturing advantages.

Reaction solvents usable for synthesis include hydrocarbons (preferably toluene and xylene), ethers (preferably dimethyl ether, tetrahydrofuran, and dioxane), ketones, esters, acetonitrile, dimethylformamide, and dimethylacetamide do. The solvent can be used independently or as a mixture of two or more. Preferred among them are toluene, acetonitrile, dimethylformamide, and dimethylacetamide.

The reaction is preferably carried out at 0 to 150 ° C, more preferably at 0 to 100 ° C, even more preferably at 0 to 90 ° C, particularly preferably at 20 to 90 ° C. The reaction is preferably carried out without base. Where a base is used, available bases include organic or inorganic bases, preferably pyridine and organic bases such as tertiary alkylamines (preferably triethylamine or ethyldiisopropylamine).

In the solution, two or more kinds of rod-shaped compounds having an absorption peak (λmax) of 250 nm or less in the UV absorption spectrum may be used in combination.

The cellulose acylate film preferably comprises fine particles as a matting agent. The microparticles usable in the present invention are silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, calcium silicate hydrate, aluminum silicate , Magnesium silicate, and calcium phosphate. Including silicon, in particular silicon dioxide, is preferred for reducing turbidity. Preferably having an average primary particle size of 20 nm or less, more preferably 5-16 nm, preferably at least 70 g / l, more preferably 90-200 g / l, even more preferably 100-200 g / l Preference is given to using silicon dioxide particles. Small primary particle sizes are advantageous for reducing haze. High apparent specific gravity allows for high concentration dispersion, which leads to reduction of haze and lumps.

The amount of the silicon dioxide fine particles, when used, is preferably 0.01 to 0.3 parts by weight per 100 parts by weight of the polymer component including cellulose acylate.

The microparticles are usually present in the film as agglomerates of primary particles to provide a film having an average particle size of 0.1-3.0 μm and a surface irregularities of 0.1-3.0 μm. The average secondary particle size is preferably 0.2-1.5 μm, more preferably 0.4-1.2 μm, even more preferably 0.6-1.1 μm. Secondary particles of 1.5 µm or more increase the haze, and those of 0.2 µm or less are insufficient for the blocking effect of film cracking.

The circumscribed diameter of the primary or secondary particles is measured by particle size under a scanning electron microscope. A total of 200 particles at different locations are measured to obtain an average particle size.

Commercially available silicon dioxide particles are available, including AEROSIL R972, R972V, R974, R812, 200, 200V, 300, R202, OX50 and TT600 (all available from Nippon Aerosil Co., Ltd.). Commercially available zirconium oxide particles, such as AEROSIL R976 and 811 (both available from Nippon Aerosil Co., Ltd.), are useful.

Among them, AEROSIL 200V and AEROSIL R972 (silicon dioxide) have an average primary particle size of 20 nm or less, have an apparent specific gravity of 70 g / l or more, and are very effective in reducing the coefficient of friction of the film while maintaining low turbidity, Particularly preferred.

Several techniques have been proposed for preparing a matte dispersion for obtaining a cellulose acylate film comprising small secondary particles of the matte. On the method, the mat agent and the fine particles of the solvent are mixed by stirring to prepare a dispersion. Separately, a cellulose acylate solution (dope) is prepared. The mat dispersion is added to a small portion of the cellulose acylate solution, stirred to dissolve, and mixed with the rest of the dope. By this method, the silicon dioxide particles can be well dispersed and hardly reaggregate. Alternatively, a small amount of cellulose acylate is stirred and dissolved in a solvent, fine particles are added thereto and dispersed in a disperser. The resulting dispersion is thoroughly mixed with dope in an inline mixer. The present invention is not limited to this method. When dispersing the silicon dioxide particles in the solvent or solution, the silicon dioxide concentration is preferably 5-30% by weight, more preferably 10-25% by weight, even more preferably 15-20% by weight. High concentration dispersions result in low liquid turbidity with respect to the amount added, reducing haze and aggregation. The amount of the mat agent of the final cellulose acylate dope is preferably 0.01 to 1.0 g / m 2, more preferably 0.03 to 0.3 g / m 2, even more preferably 0.08 to 0.16 g / m 2.

Solvents used in the preparation of the matte dispersions preferably include low alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, and butyl alcohol, and organic solvents usable in the preparation of cellulose acylate dope.

In order to manufacture the cellulose acylate solution (dope) for film formation, the organic solvent which can be used at the time of cellulose acylate dissolution is described.

Both the chlorine-containing solvent system including the chlorine-containing organic solvent as the main solvent and the chlorine-removing organic solvent system can be used in the present invention. Chlorine-containing organic solvents are preferably used as the main solvent when preparing the cellulose acylate solution. The chlorine-containing organic solvent is not particularly limited as long as it can dissolve cellulose acylate to provide a casting dope. Preferred chlorine-containing organic solvents include dichloromethane and chloroform, with dichloromethane being more preferred. Chlorine-containing organic solvents can be used in combination with other organic solvents. However, in this case, dichloromethane should be used at a ratio of 50% by weight or more based on the organic solvent system. Other organic solvents usable in combination with chlorine-containing solvents preferably include esters, ketones, ethers, alcohols, and hydrocarbons, each having 3 to 12 carbon atoms. Esters, ketones, ethers and alcohols may have a cycle structure. Also useful are compounds having two or more functional groups selected from ester groups, ketone groups, and ether groups (ie, -O-, -CO-, and -COO-). It may also have other functional groups such as alcoholic hydroxyl groups. In the case of such an organic solvent having two or more kinds of functional groups, the number of carbon atoms contained in the solvent compound should be within the range cited as a compound having any one of the functional groups. Esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate, and pentyl acetate. Ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, and methylcyclohexanone. Ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole, and phentol . Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol, and 2-butoxyethanol.

Alcohols usable in combination with chlorine-containing organic solvents may be straight chain, branched or cyclic and preferably comprise saturated aliphatic hydrocarbons. The hydroxyl group of the alcohol can be primary, secondary or tertiary. Examples of alcohols are methanol, ethanol, 1-propanol, 2-propyl alcohol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, 2-methyl-2-butanol and cyclohexanol. Fluoroalcohols such as 2-fluoroethanol, 2,2,2-trifluoroethanol, and 2,2,3,3-tetrafluoro-1-propanol are also useful. Hydrocarbons usable in combination with chlorine-containing organic solvents may be straight chain, branched or cyclic and include aromatic hydrocarbons and aliphatic hydrocarbons. Fatty hydrocarbons may be saturated or unsaturated. Examples of hydrocarbons are cyclohexane, hexane, benzene, toluene, and xylene.

Combination examples of chlorine-containing organic solvents with other organic solvents include, but are not limited to:

(1) dichloromethane / methanol / ethanol / butanol (weight ratio 80/10/5/5, the same as below)

(2) dichloromethane / acetone / methanol / propanol (80/10/5/5)

(3) dichloromethane / methanol / butanol / cyclohexane (80/10/5/5)

(4) dichloromethane / methyl ethyl ketone / methanol / butanol (80/10/5/5)

(5) dichloromethane / acetone / methyl ethyl ketone / ethanol / isopropyl alcohol (75/8/5/5/7)

(6) dichloromethane / cyclopentanone / methanol / isopropyl alcohol (80/7/5/8)

(7) dichloromethane / methyl acetate / butanol (80/10/10)

(8) dichloromethane / cyclohexanone / methanol / hexane (70/20/5/5)

(9) dichloromethane / methyl ethyl ketone / acetone / methanol / ethanol (50/20/5/5)

(10) dichloromethane / 1,3-dioxolane / methanol / ethanol (70/20/5/5)

(11) dichloromethane / dioxane / acetone / methanol / ethanol (60/20/10/5/5)

(12) dichloromethane / acetone / cyclopentanone / ethanol / isobutanol / cyclohexane (65/10/10/5/5/5)

(13) dichloromethane / methyl ethyl ketone / acetone / methanol / ethanol (70/10/10/5/5)

(14) dichloromethane / acetone / ethyl acetate / ethanol / butanol / hexane (65/10/10/5/5/5)

(15) dichloromethane / methyl acetoacetate / methanol / ethanol (65/20/10/5), and

(16) dichloromethane / cyclopentanone / ethanol / butanol (65/20/10/5)

The chlorine-removing organic solvent that can be used as the main solvent in preparing the cellulose acylate dope is not particularly limited as long as it can dissolve the cellulose acylate to provide a casting dope. Preferred chlorine-free organic solvents include esters, ketones, and ethers, each containing from 3 to 12 carbon atoms and may have a cycle structure. Compounds having two or more functional groups selected from ester groups, ketone groups, and ether groups (ie, -O-, -CO-, and -COO-) are also useful as main solvents. It may also have other functional groups such as alcoholic hydroxyl groups. In the case of such an organic solvent having two or more kinds of functional groups, the number of carbon atoms contained in the solvent compound should be within the range cited as a compound having any one of the functional groups. Esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate, and pentyl acetate. Ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, and methylcyclohexanone. Ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole, and phentol . Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol, and 2-butoxyethanol.

In view of the various aspects described above, it is selected from chlorine-removing organic solvents. More specifically, the chlorine-removing organic solvent which is preferably used in the present invention is a mixed solvent system comprising the above-described chlorine-removing organic solvent as a main component. The mixed solvent system preferably comprises a first solvent component selected from methyl acetate, ethyl acetate, methyl formate, ethyl formate, acetone, dioxolane, dioxane, and mixtures thereof, and ketones and acetos having 4 to 7 carbon atoms. A second solvent component selected from the acetic ester and a third solvent component selected from an alcohol or hydrocarbon having 1 to 10 carbon atoms, in particular an alcohol having 1 to 8 carbon atoms. When the first solvent component is a mixture, the second solvent component can be omitted. The first solvent component is preferably methyl acetate, acetone, methyl formate, ethyl formate or mixtures thereof, and the second solvent component is preferably methyl ethyl ketone, cyclopentanone, cyclohexanone or methyl acetylacetate. The second solvent component may be a mixture of solvents listed as preferred second solvent components.

As the second solvent component, the alcohol may be linear or branched or cyclic, and may preferably comprise saturated aliphatic hydrocarbons. The hydroxyl group of the alcohol can be primary, secondary or tertiary. Examples of alcohols are methanol, ethanol, 1-propanol, 2-propyl alcohol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, 2-methyl-2-butanol, and cyclohexanol. Fluoroalcohols such as 2-fluoroethanol, 2,2,2-trifluoroethanol, and 2,2,3,3-tetrafluoro-1-propanol are also useful. As the third solvent component, the hydrocarbon may be linear, branched or cyclic, and may include aromatic hydrocarbons and aliphatic hydrocarbons. Fatty hydrocarbons may be saturated or unsaturated. Examples of hydrocarbons are cyclohexane, hexane, benzene, toluene, and xylene. The third solvent component may be a single compound or a mixture of two or more compounds selected from these alcohols and hydrocarbons. Examples of preferred third solvent components include methanol, ethanol, 1-propanol, 2-propyl alcohol, 1-butanol, 2-butanol, cyclohexanol, cyclohexane, and hexane. Particular preference is given to methanol, ethanol, 1-propanol, 2-propyl alcohol, and 1-butanol.

The chlorine-removing mixed solvent system preferably comprises 20 to 95% by weight of the first solvent component, 2 to 60% by weight of the second solvent component, and 2 to 30% by weight of the third solvent component. More preferably, the system comprises 30 to 90% by weight of the first component, 3 to 50% by weight of the second component, and 3 to 25% by weight of alcohol as the third component. Even more preferably, the solvent system comprises 30 to 90% by weight of the first component, 3 to 30% by weight of the second component, and 3 to 15% by weight of alcohol as the third component. More detailed information on the chlorine-free organic solvent systems usable in the present invention is given in the Journal of Technical Disclosure, No. 2001-1745, pp. 12-16, Japanese Society of Invention and Innovation, March, 2001.

Preferred configurations of the chlorine-removing organic solvent system include, but are not limited to:

(1) methyl acetate / acetone / methanol / ethanol / butanol (weight ratio 75/10/5/5/5, the same below)

(2) methyl acetate / acetone / methanol / ethanol / propanol (75/10/5/5/5)

(3) methyl acetate / acetone / methanol / butanol / cyclohexane (75/10/5/5/5)

(4) methyl acetate / acetone / ethanol / butanol (81/8/7/4)

(5) methyl acetate / acetone / ethanol / butanol (82/10/4/4)

(6) methyl acetate / acetone / ethanol / butanol (80/10/4/6)

(7) Methyl Acetate / Methyl Ethyl Ketone / Methanol / Butanol (80/10/5/5)

(8) Methyl acetate / acetone / methyl ethyl ketone / ethanol / isopropyl alcohol (75/8/5/5/7)

(9) Methyl Acetate / cyclopentanone / methanol / isopropyl alcohol (80/7/5/8)

(10) methyl acetate / acetone / butanol (85/10/5)

(11) Methyl Acetate / cyclopentanone / acetone / methanol / butanol (60/15/14/5/6)

(12) Methyl Acetate / cyclohexanone / methanol / hexane (70/20/5/5)

(13) Methyl acetate / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5)

(14) Methyl acetate / 1,3-dioxolane / methanol / ethanol (70/20/5/5)

(15) Methyl acetate / dioxane / acetone / methanol / ethanol (60/20/10/5/5)

(16) Methyl acetate / acetone / cyclopentanone / ethanol / isobutanol / cyclohexane (65/10/10/5/5/5)

(17) methyl formate / methyl ethyl ketone / acetone / methanol / ethanol (50/20/5/5)

(18) Methyl formate / acetone / ethyl acetate / ethanol / butanol / hexane (65/10/10/5/5/5)

(19) Acetone / methyl acetoacetate / methanol / ethanol (65/20/10/5)

(20) Acetone / cyclopentanone / ethanol / butanol (65/20/10/5)

(21) acetone / 1,3-dioxolane / ethanol / butanol (65/20/10/5), and

(22) 1,3-dioxolane / cyclohexanone / methyl ethyl ketone / methanol / butanol (55/20/10/5/5/5)

In addition to the above, cellulose acylate is dissolved in a mixed solvent of 81/8/7/4 parts by weight of methyl acetate, acetone, ethanol, and butanol, the solution is filtered and concentrated, and 2 parts by weight of butanol in a concentrated solution. Method of adding; Cellulose acylate is dissolved in a mixed solvent of 84/10/4/2 parts by weight of methyl acetate, acetone, ethanol, and butanol, the solution is filtered and concentrated, and 4 parts by weight of butanol is added to the concentrated solution. Way; Cellulose acyl by dissolving cellulose acylate in a mixed solvent of 84/10/6 parts by weight of methyl acetate, acetone, and ethanol, filtering the solution, concentrating, and adding 5 parts by weight of butanol to the concentrated solution. Rate solutions can be prepared.

The dope based on the chlorine-free solvent system may comprise up to 10% by weight of dichloromethane based on the total solvent system.

The cellulose acylate solution (dope) for film formation preferably has a concentration of 10 to 30% by weight, more preferably 13 to 27% by weight, even more preferably 15 to 25% from the viewpoint of casting suitability. The method of preparing the cellulose acylate solution is not limited as long as the desired concentration is shown. For example, to provide a planned concentration, a predetermined amount of cellulose acylate may be dissolved in a solvent, or a solution of a lower concentration (eg, 9-14% by weight) than the planned one may be prepared once more Adjust to high concentration as shown. Conversely, it is also possible to prepare a solution at a higher concentration than planned and to add various additives therein to derive the desired concentration.

In view of the peelability or release property of the cast film from the casting support, the cellulose acylate solution is a collection of cellulose acylate molecules in a solution diluted to a concentration of 0.1 to 5% by weight using the same solvent system ( Resultant) preferably have a molecular weight of 150,000 to 15,000,000, more preferably 180,000 to 9,000,000. The molecular weight of the aggregate is obtained by a static light scattering method. The dilute cellulose acylate solution is such that the RMS radius is preferably 10-200 nm, more preferably 20-200 nm, which is determined simultaneously in the molecular weight measurement by the static light scattering method. Furthermore, the dilute cellulose acylate solution preferably has a secondary vireal coefficient in the range of ^{-2x10 -4} to + ^{4x10 -4} , more preferably in the range of -2x10 ^-4 to + 2x10 ^-4 . It is

The molecular weight, RMS radius, and secondary vireal coefficient of the aggregate of cellulose acylate solutions are measured by the following static light scattering method. Although these measurements are performed in dilute solutions, the measurement results fully reflect the action of the dope.

Cellulose acylate dried at 120 ° C. for 2 hours is dissolved in the same solvent used to prepare the dope to prepare dilute solutions having concentrations of 0.1%, 0.2%, 0.3%, and 0.4% by weight. . To prevent moisture absorption, the cellulose acylate is weighed at 25 ° C. and 10% RH. Dissolution is carried out under the temperature conditions (at room temperature or under cooling or heating) applied in the preparation of the dope. The solution and solvent were filtered through a 0.2 μm Teflon filter and incremented by 10 ° at 25 ° C. during static light scattering on a light scattering spectrophotometer DLS-700 (manufactured by Otsuka Electronics Co., Ltd.) at variable angles of 30 ° to 140 °. Is measured. Obtained static light scattering data is analyzed by Berry plot. Solvent refractive index, needed for analysis, is obtained using an Abbe refractometer system, and refractive index increment (dn / dc), which is also required for analysis, is a differential refractometer with the same solvent and solution used for light scattering measurements. It is measured by 1021 (manufactured by Otsuka Electronics).

The cellulose acylate solution (dope) for film formation is prepared by any method, ie, cooling at room temperature or at high temperature, or a combination thereof. Details of the preparation of cellulose acylate dope are described, for example, in JP-A-5-163301, JP-A-61-106628, JP-A-58-127737, JP-A-9-95544, JP-A-10 -95854, JP-A-10-45950, JP-A-2000-53784, JP-A-11-322946, JP-A-11--322947, JP-A-4-259511, JP-A-2000- 273184, JP-A-11-323017, and JP-A-11-302388. Known techniques relating to the dissolution of cellulose acylate in organic solvents are appropriately applied to the present invention, unless the scope and spirit of the present invention are inconsistent. More specifically, especially for chlorine-removing solvent systems, the Journal of Thechnical Disclosure, No. 2001-1745, pp. 22-25, Japanese Society of Invention and Innovation, March, 2001. Concentration and filtration, usually associated with the preparation of cellulose acylate dope, are described in the same book, p. See 25. When cellulose acylate is dissolved in an organic solvent at high temperatures, the heating temperature is in all cases above the boiling point of the solvent. In such a case, the system is under pressure.

The cellulose acylate dope preferably has the following viscosity and dynamic storage modulus to ensure easy casting. 1 ml of sample solution is measured with a flow meter CSL 500 (manufactured by TA Instruments Inc.) using a stainless steel cone and plate geometry (cone diameter of 4 cm and an angle of 2 °) (manufactured by TA Instruments). In oscillation mode the temperature gradient is applied by varying from 40 ° C. to −10 ° C. at a rate of 2 ° C./min. The static non-Newtonian viscosity n * (Pa · s) at 40 ° C. and storage modulus G ′ (pa) at −5 ° C. are measured. Prior to the start of the measurement, the sample solution is maintained at the starting temperature until the solution temperature is constant. It is preferable that dope has a viscosity of 1-400 Pa.s at 40 degreeC, and has a dynamic storage modulus of 500 Pa or more at 15 degreeC. More preferably, the dope has a viscosity of 10 to 200 Pa · s at 40 ° C. and a dynamic storage modulus of 100 to 1,000,000 Pa or more at 15 ° C. It is also desirable for the dope to have a high dynamic storage modulus at low temperatures. When the casting support is at −5 ° C., for example, the dope preferably has a dynamic storage modulus of 10,000 to 1,000,000 Pa at −5 ° C. When the casting support is at -50 ° C, for example, the dope preferably has a dynamic storage modulus of 10,000 to 5,000,000 Pa at -50 ° C.

In the present invention, the use of specific cellulose acylates allows the preparation of high concentrations or very stable dope without performing the dope concentration process. Naturally, the concentration process can be applied where a low concentration of cellulose acylate solution is prepared once and then concentrated to the desired concentration to facilitate dissolution. Concentration can be carried out by any method. For example, the method of JP-A-4-259511 is useful, where a low concentration solution rotates along the inner wall of the cylinder and the inner wall of the cylinder, giving a temperature difference to the solution and thereby causing the solvent to evaporate. It is drawn into the cylinder between the faces of the cylinders. The methods disclosed in U.S. Pat. Flash-evaporated before. Solvent vapor is directed out of the container and the concentrated solution is withdrawn from the bottom of the container.

The dope is preferably filtered through a filter, such as a metal screen or flannel, to remove any insoluble matter or foreign matter (eg dust or impurities). In order to filter the cellulose acylate dope, a filter having an absolute filtration capacity of preferably 0.1 to 100 µm, more preferably 0.5 to 25 µm is used. The filter thickness is preferably 0.1 to 10 mm, more preferably 0.2 to 2 mm. At that thickness, the filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, even more preferably 1.0 MPa or less, particularly preferably 0.2 MPa or less. Filters of known filter materials are used, including glass fibers, cellulose fibers, fiber papers, and fluoropolymers such as polytetrafluoroethylene. Preference is given to filters made of ceramic or metal. The dope viscosity immediately before casting should be within the range suitable for casting, preferably 10 to 2000 Pa · s, more preferably 30 to 1000 Pa · s, even more preferably 40 to 500 Pa · s. The dope temperature immediately before casting is preferably -5 to 70 ° C, more preferably -5 to 55 ° C.

The cellulose acylate dope is cast into a film using methods and apparatus commonly employed to effect solvent casting. The dope prepared in the dissolution tank is stored once in the storage tank while the foam is removed. The resulting final dope is fed to the pressure die through a pressure pump, for example a constant batch gear pump capable of accurate metering by the number of revolutions, and evenly cast through the slot of the pressure die on an endlessly moving metal support. When the dope on the support is about one turn and reaches the release site, by that time the dope is semi-dried and the semi-dried dope, called the web, is peeled off from the support. The web is transported by the tenter with its width fixed by the clip, which is then dried while drying between the roll groups of the dryer, and wound around the winder to the prescribed length. The combination of the dryer and tenter with rolls is changed according to the purpose. Where functional protective films are produced for applications in electronic displays, coaters may be used in addition to solvent casting equipment to provide functional layers such as undercoats, antistatic layers, anti-halation layers, or protective layers on cellulose acylate cast films. Often used.

Each step involved in forming the cellulose acylate film will be described briefly below, but the present invention is not limited thereto.

Finally the prepared dope is cast on a rotating drum or band (support) and the solvent is evaporated to form a film. The dope to be cast is preferably adjusted to have a solids content of 5 to 40% by weight. The support surface is preferably mirror finished. Preferably the support surface temperature is 30 degrees C or less, More preferably, it is -10-20 degreeC. Casting method is JP-A-2000-301555, JP-A-2000-301558, JP-A-7-32391, JP-A-3-193316, JP-A-5-86212, JP-A-62-37113 , JP-A-2-276607, JP-A-55-14201, JP-A-2-111511, and JP-A-2-208650.

Solvent casting can be performed using a single cellulose acylate dope or cast on the same support (layered casting) using two or more cellulose acylate dope to obtain a laminated casting film. Layered casting may be performed by dope casting through each die provided with space in the direction of movement of the support. The techniques described in JP-A-61-158414, JP-A-1-122419, and JP-A-11-198285 can be applied. Layered castings are also described, for example, in JP-B-60-27562, JP-A-61-94724, JP-A-61-947245, JP-A-61-104813, JP-A-61-158413, And casting two dope simultaneously through each die slot described in JP-A-6-134933. The solvent casting technique proposed in JP-A-56-162617 is also useful, wherein the flow of high viscosity cellulose acylate dope is surrounded by the flow of low viscosity cellulose acylate dope, and the two dope are simultaneously extruded onto the support do. In a preferred embodiment, the content of the alcohol component as a bad solvent is higher for external dope than for internal dope as suggested in JP-A-61-94724 and JP-A-61-94725. The technique disclosed in JP-B-44-20235 is also useful, wherein the casting film formed by casting the first dope from the first die onto the support is peeled off and the casting film from the second die on the side in contact with the support. The second dope is cast onto the bed. The two or more cellulose acylate dope used for the layered casting may be the same or different. To impart functionality to two or more cellulose acylate layers, cellulose acylate dope suitable for each function is extruded from each slot. It is also possible to cast cellulose acylate dope simultaneously with other functional layers (eg, adhesive layers, dye layers, antistatic layers, semi-halation layers, UV absorbing layers and polarizing layers).

In order to obtain the required film thickness by single layer casting, it is necessary to extrude high concentration, high viscosity cellulose acylate dope. Such dope tends to form solids that are poor in stability and often lead to equipment failure or poor surface smooth film formation. The layered casting described above provides a solution to this problem. Since a plurality of high viscosity cellulose acylate dope is cast from each die slot at the same time on a metal support, the resulting casting film exhibits excellent surface properties such as improved smoothness. Moreover, the use of thick cellulose acylate dope contributes to reducing the drying load and improving the production rate. In the case of co-casting, the thickness of the inner layer and the thickness of the outer layer are not particularly limited. The outer thickness is preferably 1-50% of the total thickness, more preferably 2-30%. When co-casting three or more layers, the total thickness of the layer in contact with the metal support and the layer in contact with the atmosphere is defined as "outer thickness". Cellulose acylate dope with different concentrations of the aforementioned additives such as plasticizers, UV absorbers, and matting agents can be co-cast to form cellulose acylate laminate films. For example, a cellulose acylate laminated film composed of a surface layer / center layer / surface layer can be obtained. In this layer structure, the matting agent can be added to the surface layer, for example, in large amounts, or added to the surface layer alone. Plasticizers and UV absorbers may be added in large quantities to the core layer rather than to the surface layer or only to the center layer. The type of plasticizer or UV absorber can vary between the center layer and the surface layer. For example, less volatile plasticizers and / or UV absorbers can be added to the surface layer, while plasticizers with good plasticizing effects and UV absorbers with high UV absorbance can be added to the central layer. Moreover, it is preferable embodiment to add a mold release agent only to the surface of a support body side. In the case of chill-roll extrusion, it is preferable to add a large amount of alcohol, i.e., a bad solvent, to the surface layer since the dope is gelled by the cooling of the metal support. The surface layer and the center layer may have different Tg. It is preferable that the Tg of the center layer is lower than that of the surface layer. Dopes for the surface and center layers may have different viscosities. It is usually preferred that the surface layer has a lower viscosity than the center layer, but the viscosity of the center layer may be lower than the viscosity of the surface layer.

Doping casting is, for example, a method in which the prepared dope is uniformly extruded from a pressure die onto a metal support, a method in which the casting dope is flush with the doctor blade once on the metal support to control the film thickness, or The film thickness is carried out by a method using a reverse roll coater, which is controlled by roll rotation in the reverse direction. Preference is given to using a pressure die. The pressure dies include hanger type and T-die type in addition to the above-described method, each of which can preferably be used. A variety of known solvent casting techniques can be used to form cellulose acylate films. By properly selecting the conditions taking into account the differences, for example the boiling point of the solvent, the effects and advantages reported in the publication are obtained.

Metal supports used and continuously moving in solvent casting include drums surface-finished by chrome plating, and surface mirror-polished stainless steel belts or bands. One or more pressure dies are provided on the metal support. The preferred number of pressure dies is one or two. When two or more pressure dies are provided, the casted dope may be dispensed in an appropriate amount for each die. It is also possible to provide the die with the desired amount of dope, each using a precise metering gear pump. The temperature of the cellulose acylate dope to be cast is preferably in the range of -10 to 55 ° C, more preferably 25 to 50 ° C. The dope temperature may be kept constant or may vary from step to step through the process involved in dope preparation. In the latter case, the temperature immediately before casting should be a predetermined level.

The cellulose acylate web on the metal support is usually dried by blowing hot air to the metal support (drum or belt), i.e. the web exposed surface on the metal support or the inner side of the drum or belt, or the drum or belt (ie casting by heat transfer) It is usually dried by applying a temperature-controlling liquid to the inner surface of the drum or belt to heat the side opposite to the surface and control its surface temperature. Liquid heat transfer methods are preferred. The surface temperature of the metal support is not limited as long as it is not higher than the boiling point of the solvent used for the dope. In order to enhance the drying or fluidity loss of the web on the metal support, it is desirable to set the support surface at 1-10 ° C. below the lowest boiling point of the solvent used in the dope, but this is when the web is stripped without cooling and drying Does not apply to

The retardation of the cellulose acylate casting film can be controlled by stretching. Positive stretching in the width direction is, for example, JP-A-62-115035, JP-A-4- 152125, JP-A-4-284211, JP-A-4-298310, and JP-A-11 It is proposed as disclosed in -48271. By stretching, the in-plane retardation value of the cellulose acylate film can be improved.

Stretching is carried out at room temperature or under heating. The heating temperature is preferably below the glass transition temperature of the film. The film can be stretched uniaxially (in the longitudinal or transverse direction) or biaxially. Biaxial stretching may be performed simultaneously or sequentially. The stretching ratio is 1 to 200%, preferably 1 to 100%, and more preferably 1 to 50%. It is preferable that the birefringent optical film has a larger refractive index in the horizontal axis direction than in the long axis direction. Therefore, it is recommended to stretch the film at a higher ratio in the horizontal axis direction than in the long axis direction. The stretching step may be carried out in a separate line on the film which is incorporated into the film forming line or released from the roll. In the former case, a film comprising residual solvent can be stretched. The residual solvent content of the stretched film is preferably 2-30%.

The thickness of the cellulose acylate film (after drying) depends on the intended use. Usually 5-500 micrometers, Preferably it is 20-300 micrometers, More preferably, it is the range of 30-150 micrometers. In order to use for a VA mode liquid crystal display, 40-110 micrometers is preferable.

The desired film thickness can be obtained by adjusting the solid concentration of the dope, the slot gap of the die, the extrusion pressure from the die, the moving speed of the metal support, and the like.

The width of the resulting cellulose acylate film is preferably 0.5 to 3 m, more preferably 0.6 to 2.5 m, even more preferably 0.8 to 2.2 m. The length of the rolled film per roll is preferably 100 to 10,000 m, more preferably 500 to 7,000 m, even more preferably 1,000 to 6,000 m. When the film is wound, it is desirable to be knurl at least along its edge. The null width is preferably 3 to 50 mm, more preferably 5 to 30 mm, and the height of the null is preferably 0.5 to 500 µm, more preferably 1 to 200 µm. The board can be single sided or double sided.

The Re (590) change in the width direction is preferably within ± 5 nm, more preferably ± 3 nm. The change in Rth (590) in the width direction is preferably ± 10 nm, more preferably ± 5 nm. The same selection applies to variations of the long axis Re 590 and Rth 590 in the longitudinal direction.

In order to ensure the viewing angle of the LCD, in particular VA mode LCD, it is preferred that the cellulose acylate protective film has optical properties satisfying the formulas (7) and (8):

20nm≤Re (590) ≤200nm (7)

70nm≤Rth (590) ≤400nm (8)

The ratio of Re (590) to Rth (590) is preferably 0.1 to 0.8, more preferably 0.25 to 0.6. These optical properties can be controlled by selection of the type and amount of the additive and the draw ratio.

In the present invention, Re (λ) and Rth (λ) represent in-plane retardation and thickness direction retardation at wavelength λ. Re (λ) is measured with the phase difference measuring system KOBRA 21ADH (manufactured by Oji Scientific Instruments) while light of wavelength λ is incident in the direction perpendicular to the film surface. Rth (λ) is estimated by KOBRA 21ADH on the basis of the retardation value measured in three directions: the retardation value measured in three directions is the Re (λ) obtained from the first and the tilt (rotation) axis. A retardation measured during the incidence of light having a wavelength of λ nm in a direction rotated by + 40 ° with respect to the vertical direction of the film around the in-plane slow axis measured by KOBRA 21ADH, and the third is the tilt (rotation) axis, Retardation measured during the incidence of light of wavelength lambda nm in the direction rotated by -40 ° with respect to the vertical direction of the film around the in-plane slow axis measured by KOBRA 21ADH. Hypothetical values of average refractive index and film thickness are also required for estimation. The assumption of average refractive index is Polymer Handbook, Jhon Wiley & Sons, Inc. And catalogs of various optical films. The average refractive index of cellulose acylate is 1.48. As a result, KOBRA 21ADH estimates nx, ny, and nz.

The cellulose acylate film is applied to both sides of the VA mode liquid crystal cell or only one side. When applied to both sides, the cellulose acylate film preferably has a Re of 20-100 nm, more preferably 30-70 nm, and preferably has a Rth of 70-300 nm, more preferably 100-200 nm. When applied only to one side, the film preferably has a Re of 30 to 150 nm, more preferably 40 to 100 nm, and preferably has a Rth of 100 to 300 nm, more preferably 150 to 250 nm.

The change in in-plane slow axis angle of the cellulose acylate film is preferably in the range of ± 2 °, more preferably ± 1 °, even more preferably ± 0.5 ° from the reference direction of the roll film. The "reference direction" is the long axis direction when the film is a stretched film in length, and the transverse direction when the film is a stretched film in transverse direction.

The cellulose acylate film preferably has a deviation ΔRe of 0-10 nm between the Re value measured at 25 ° C. and 10% RH and the value at 25 ° C. and 80% RH (= Re 10% RH-Re 80% RH), There is a deviation ΔRth between 0 and 30 nm between the Rth value measured at 25 ° C and 10% RH and the value at 25 ° C and 80% RH (= Rth10% RH-Rth80% RH), which is the color of LCD It is effective in reducing change.

The cellulose acylate film preferably has an equilibrium moisture content of less than 3.2% at 25 ° C. and 80% RH, which is also effective in reducing the color change of the LCD over time. The moisture content of the cellulose acylate film is measured on a 7 mm wide and 35 mm long specimen according to Karl Fischer's method using a moisture meter CA03 and a sample dryer VA05 (both available from Mitsubishi Chemical Corp.). The moisture content (g) is divided by the sample weight (g) to provide the moisture content (%).

The cellulose acylate film is preferably normalized to a film thickness of 80 μm and has water permeability in terms of water vapor permeability (hereinafter referred to as WVTR) of 400 to 1800 g / m 2 · 24hr at 60 ° C. and 95% RH. It is advantageous to reduce the color change of the LCD over time. WVTR decreases with film thickness. This is because the WVTR is normalized to a film thickness of 80 μm regardless of the thickness of the sample. The WVTR normalized to a film thickness of 80 μm is calculated from the formula: Measured WVTR × measured film thickness (μm) / 80 μm. WVTR measurements were measured by Kobunshi no Bussei II (Kobunshi Jikken Koza 4), Kyoritsu Shuppan, pp. 285-294: Joki Toka Ryo no Sokutei (Shituryo Ho, Ondokei Ho, Jokiatsu Ho, Kyuchaku Ho).

The glass transition temperature (Tg) of the cellulose acylate film is measured as follows. Prior to the measurement, 5 mm wide and 30 mm long specimens cut from unstretched cellulose acylate film are set to 25 ° C. and 60% RH conditions for at least 2 hours. Tg is a dynamic viscoelasticity measuring instrument Vibron manufactured by ITK Co., Ltd. at a heating rate of 2 ° C./min from 30 ° C. to 200 ° C., at a sample length between 20 mm of grips, and at a period of 1 Hz. Measured by DVA-225. The storage modulus is plotted on a logarithmic coordinate with the log longitudinal axis and temperature (° C.). Line 1 (solid region) and line 2 (glass transition region) are shown which show a sharp decrease in storage modulus observed in the phase transition from the solid region to the glass transition region. The intersection of lines 1 and 2 represents the temperature at which the storage modulus begins to decrease rapidly and the temperature at which the film begins to soften, ie the temperature at which the film begins to change into the glass transition region. This temperature is called the glass transition temperature Tg (dynamic viscoelastic).

The cellulose acylate film preferably has a haze of 0.01 to 2%. Haze is measured with a haze meter HGM-2DP (manufactured by Suga Test Instruments Co., Ltd.) according to JIS K6714 in a 40 mm wide and 80 mm long specimen.

The cellulose acylate film exhibits a mass change that is preferably no greater than 5% at 80 ° C. and 90% RH for 48 hours, and 90 ° C. and 5% RH days at 60 ° C. and 95% RH for 24 hours or 24 hours. When the dimension change is not more than 5%.

The cellulose acylate film preferably has a photoelastic coefficient of 50 × 10 ⁻¹³ cm 2 / dyne or less to reduce the color change of the LCD over time. The photoelastic coefficient is measured by applying tensile stress in the long axis direction to 10 mm wide and 100 mm long specimens and measuring retardation with an ellipsometer M150 (manufactured by JASCO Corp.). The photoelastic coefficient is calculated from changing the retardation with stress.

The protective film usable in the present invention further includes a polymer film having an optically anisotropic layer. The optically anisotropic layer is preferably composed of a transparent polymer film, an alignment film, and an optically anisotropic layer in this order.

The alignment layer may be provided by rubbing a layer formed of an organic compound, depositing an inorganic compound by oblique vacuum deposition, or forming a layer with micro grooves. Alignment layers are also known which develop an alignment function by electric or magnetic field application or light irradiation. Particular preference is given to an alignment layer formed by the orientation of the polymer layer. The rubbing treatment is preferably carried out by rubbing the surface of the polymer layer several times in a given direction with paper or cloth. The rubbing direction is preferably substantially parallel to the absorption axis of the polarizer. Preferred polymers for preparing the alignment layer include polyimide, polyvinyl alcohol, and the polymers described in JP-A-9-152509. The alignment layer preferably has a thickness of 0.01 to 5 µm, more preferably 0.05 to 2 µm.

The optically anisotropic layer preferably comprises a liquid crystal compound, particularly preferably a discotic liquid crystal compound. Discotic liquid crystal compounds have a discotic core with radially extended side chains, as typically illustrated by the triphenylene derivatives shown below.

Triphenylene Derivatives:

Substituents that react to heat or light applications may be mixed. Preferred examples of discotic liquid crystal compounds are provided in JP-A-8-50206.

Discotic liquid crystal molecules adjacent to the alignment layer are arranged in parallel with the rubbing direction of the alignment layer having the pretilt angle. Discotic liquid crystal molecules on the side facing the atmosphere are arranged almost vertically. Therefore, the discotic liquid crystal layer exhibits a hybrid arrangement as a whole, thereby widening the viewing angle of the TN mode TFT-LCD.

An optically anisotropic layer usually applies a solution of discotic compounds and other materials (eg, polymerizable monomers and photopolymerization initiators) in a solvent as an alignment layer, dries the coating film, and coats the coating film with a discotic nematic phase formation. It is obtained by heating to a temperature and polymerizing the monomer by, for example, UV irradiation after cooling. The discotic liquid crystal compound used in the present invention preferably has a discotic nematic liquid crystal phase-solid phase transition temperature of 70 to 300 ° C, more preferably 70 to 170 ° C.

Compounds added to optical anisotropy in addition to discotic compounds are not particularly limited as long as they are compatible with the discotic compound and do not interfere with the orientation of the discotic compound, for example, helping the discotic compound molecule to change the tilt angle. Compound. Useful compounds are preferably polymerizable monomers (e.g., compounds having vinyl, vinyloxy, acryloyl or methacryloyl groups), fluorine-containing triazine compounds which perform orientation control in terms of facing the atmosphere. And polymers such as cellulose acetate, cellulose acetate propionate, hydroxypropyl cellulose, and cellulose acetate butyrate. These compounds are added in an amount of usually 0.1 to 50% by weight, more preferably 0.1 to 30% by weight, based on the discotic compound.

The thickness of the optically anisotropic layer is preferably 0.1 to 10 µm, more preferably 0.5 to 5 µm.

The optically anisotropic layer may be a non-liquid crystalline polymer prepared by applying a solution of the non-liquid crystalline compound in a solvent to a substrate and then thermally drying. Useful non-liquid crystal compounds include polymers such as polyamides, polyimides, polyesters, polyether ketones, polyaryl ether ketones, polyamide-imides, and polyester-imides. Such polymers are applicable alone or as mixtures of two or more with other functional groups, such as mixtures of polyaryl ether ketones and polyamides. Of these polymers, polyimides are preferred in view of high transparency, high orientation properties, and high elongation. The substrate is preferably a triacetyl cellulose (TAC) film.

The stacking of the non-liquid crystal layer and the substrate may preferably be burnt 1.5 times in the transverse direction by the tenter. The stretched stack is thus applied as a polarizer on the side of the substrate facing the polarizer.

The optically anisotropic layer may also be an oriented and fixed cholesteric liquid crystal layer that selectively reflects light in the wavelength region below 350 nm. The cholesteric liquid crystal compounds include JP-A-3-67219, JP-A-3-140921, JP-A-5-61039, JP-A-6-186534, and JP-A exhibiting the selective reflections listed above. Selected from those described in -9-133810. In view of the stability of the alignment layer fixed layer, the cholesteric liquid crystal layer may be polymerized by light or heat application to form a cholesteric liquid crystal polymer, a nematic liquid crystal polymer comprising a chiral agent, or such a liquid crystal polymer. Are formed into compounds.

As an optically anisotropic layer, a cholesteric liquid crystal layer is formed by coating a cholesteric liquid crystal compound on a board | substrate, for example. For phase difference control or the like, a cholesteric liquid crystal compound may be applied in a layer, or another cholesteric liquid crystal compound may be applied in a layer. Application is carried out by a suitable coating method such as gravure coating, die coating, or dipping. The substrate is preferably a TAC film or any other polymer film.

In order to produce the liquid crystal-containing optically anisotropic layer, any method for liquid crystal alignment is taken. Among them, there is a method in which a liquid crystal compound is applied on the alignment layer and aligned by it. The alignment layer may be a rubbing layer of an organic compound (eg a polymer), an obliquely deposited layer of an inorganic compound, a layer having microgrooves, and an organic compound (eg, ω-tricosanoic acid, dioctadecylmethylammonium chloride And a layer formed by accumulating a Langmuir-Blodgett (LB) membrane of methyl stearate. Also included is an alignment layer that develops the alignment function by light irradiation. Furthermore, an alignment technique (see JP-A-3-9325) in which the liquid crystal molecules are applied to and oriented by the stretched film or a technique in which the liquid crystal molecules are oriented in an applied electric or magnetic field may be used. It is preferable that the liquid crystal alignment is as uniform as possible, and that the liquid crystal molecules in the layer are fixed in an alignment state.

The polarizing plate of the present invention, in which the cellulose acylate film is used as a protective film of the polarizer, is produced by a general method without particular limitation. For example, the cellulose acylate film is treated with alkali and attached to one or both sides of the PVA polarizer by an aqueous solution of fully saponified PVA. The cellulose acylate film can be treated for simple adhesion instead of alkali treatment, as described in JP-A-6-94915 and JP-A-6-118232. Adhesives that can be applied between the surface of the treated protective film and the polarizer include PVA adhesives such as PVA and polyvinyl butyral and vinyl latiss such as butyl acrylate. The polarizing plate consists of a polarizer and a protective film on both sides thereof. It is possible for the polarizer to be further protected by a releaseable protective sheet on one side thereof and further protected by a separate sheet on the other side. Both the releasable protective sheet and the separate sheet protect the polarizer during product shipment or inspection. The protective sheet is for protecting the viewer side of the polarizer, while the separate sheet is for covering the adhesive layer attaching the polarizer to the liquid crystal cell. The cellulose acylate protective film is preferably attached to the polarizer while allowing the slow axis to coincide with the transmission axis of the polarizer.

If the right-angle precision (perpendicular to the transmission axis of the polarizer) exceeds 1 ° between the slow axis of the cellulose acylate film and the absorption axis of the polarizer, the polarizing plate assembled under orthogonal nicotine degrades the polarization performance under orthogonal nicotine, resulting in light leakage. Cause. When combined with a liquid crystal cell, such a polarizer will be difficult to provide sufficient black level or contrast. Therefore, the deviation in the direction of the main refractive index nx of the cellulose acylate film from the transmission axis of the polarizer is preferably within 1 °, more preferably within 0.5 °.

If desired, the cellulose acylate film may be surface treated to have improved adhesion to functional layers such as primer layers or back coating layers. Suitable surface treatments include glow discharge treatment, UV irradiation treatment, corona treatment, salt treatment, and alkali treatment. The glow discharge treatment may be a low temperature plasma treatment under a low gas pressure of 10 ⁻³ to 20 Torr or a plasma treatment under atmospheric pressure. Plasma gases forming plasma under the above conditions include argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, fluorocarbons such as tetrafluoromethane, and mixtures thereof. Plasma forming gas is described in Journal of Technical Disclosure, No. 2001-1745, pp. 30-32, Japanese Association of Invention and Innovation, March, 2001. Atmospheric pressure plasma treatment, which has recently attracted attention, applies irradiation energy of 20 to 500 kGy under 10 to 1000 keV, more preferably 20 to 300 kGy under 30 to 500 keV. Of the surface treatments described above, alkali treatment (ie, saponification) is particularly effective in improving the adhesion of cellulose acylate films.

The alkali saponification treatment is preferably carried out by mixing the cellulose acylate film directly into the saponification solution tank or by coating the film with the saponification solution by dip coating, curtain coating, extrusion coating, bar coating, extrusion slide coating or the like. The solvent used in the preparation of the saponification solution should be chosen to have a good wetting characteristic on the cellulose acylate film without causing surface abnormalities and to maintain the film surface in an excellent state. In this respect, alcohol solvents, in particular isopropyl alcohol, are preferred. An aqueous solution of the surface active agent can also act as a solvent. The alkali of the saponification solution is chosen to be soluble in the selected solvent. Preference is given to potassium hydroxide or sodium hydroxide. The pH of the saponification solution is preferably at least 10, more preferably at least 12. Alkali saponification is preferably carried out at room temperature for 1 second to 5 minutes, more preferably for 5 seconds to 5 minutes, even more preferably for 20 seconds to 3 minutes. After the saponification reaction, the saponified surface of the cellulose acylate film is preferably washed with water or continuously with acid and water.

The polarizing plate of the present invention preferably has at least one functional layer selected from a hard coat layer, an antiglare layer, and an antireflective layer provided on the surface of the protective film on the other side of the polarizing plate. That is, as shown in Figure 1, when employed in the liquid crystal display, it is preferable to provide a functional layer on the protective film (TAC 2) provided on the opposite side of the polarizing plate for the liquid crystal cell. One functional layer may have a combined function. For example, the antiglare layer may have a combined function, such as an antireflection layer or a hard coat layer.

In a preferred embodiment of a polarizing plate having a functional layer on the viewer side protective film, an antireflection layer composed of a light scattering sublayer and a low refractive index sublayer and an antireflection layer composed of an intermediate refractive index sublayer, a high refractive index sublayer, and a low refractive index sublayer in this order. This is provided on the protective film on the side of the viewer.

The light scattering sublayer preferably comprises dispersed matt particles. The portion of the light scattering sublayer free of matte particles preferably has a refractive index of 1.50 to 2.00, while the low refractive index sublayer provided to the light scattering sublayer has a refractive index of 1.20 to 1.49. The light scattering sublayer has both an antiglare function and a hard coat function. The light scattering sublayer may have a single layer structure or a multi layer structure composed of, for example, two to four divided layers.

The antireflective layer is preferably designed to have the following surface profile: Ra (centerline average surface roughness) of 0.08 to 0.40 mu m; Rs not more than 10 times of Ra (10 point height parameter); Sm of 1 to 100 µm (center space between profile peaks at the center line); Standard deviation of peak height measured from the deepest valley below 0.5 μm; Standard deviation of Sm of 0.2 μm or less (center space between profile peaks at center line); And the ratio of 0 ° to 5 ° slope is more than 10%. The antireflective layer that satisfies the surface profile parameter achieves sufficient antiglare performance and uniform mat appearance when viewed visually. In order for the reflected light to have a neutral tint, the light reflected by the antireflective layer preferably has a * value of -2 to 2 and b * value of -3 to 3, under standard light source C, The minimum to maximum refractive index ratio in the wavelength region of 380 to 780 nm is preferably 0.5 to 0.99. In addition, in order to reduce yellowing of the white display, under the standard light source C, it is preferable that the b * value of the transmitted light is 0-3. Moreover, when a grid of 40 mu m x 120 mu m is disposed between the planar light source and the antireflection layer, the antireflection layer preferably has a brightness distribution of 20 or less standard deviations on its surface. With this distribution of brightness, polarizers applied to high definition panels reduce glare.

The antireflective layer preferably has a specular reflectance of 2.5% or less, a transmittance of 90% or more, and a 60 ° gloss of 70% or less. With this optical characteristic, reflection of external light is suppressed and display visibility is improved. The specular reflectivity is more preferably 1% or less, even more preferably 0.5% or less. In order to achieve non-glare and clarity of characters when applied to high-definition LCD panels, the antireflective layer preferably has a haze of 20-50%, with a total haze ratio of internal haze of 0.3 to 1, The haze of the light scattering sublayer having no low refractive index sublayer in the layer and the haze difference between the light scattering sublayer and the low refractive index sublayer formed thereon is 15% or less, and the image clarity transmitted at an optical comb width of 0.5 mm is 20%. It is -50%, and it is preferable that the transmission ratio of the vertical incident light with respect to the incident light 2 degrees away from a vertical direction is 1.5-5.0.

The low refractive index sublayer usable in forming the antireflective layer preferably has a refractive index of 1.20 to 1.49, more preferably 1.30 to 1.44. In order to ensure low refractive index, the low refractive index sublayer preferably satisfies the following equation:

(m / 4) λ × 0.7 <n1d1 <(m / 4) λ × 1.3

Where m is a positive odd number; n1 is the refractive index of the low refractive index sublayer; d1 is the thickness (nm) of the low refractive index sublayer, and λ is the wavelength in the range of 500-550 nm.

The low refractive index sublayer preferably comprises a fluoropolymer as the low refractive index binder. The fluoropolymer is preferably a polymer crosslinked by application of heating or ion irradiation, and preferably has a dynamic coefficient of friction of 0.03 to 0.20, a contact angle with water of 90 to 120 °, and a pure water droplet sliding angle of 70 ° or less. The adhesive strength of the low refractive index sublayer on commercially available and pressure sensitive adhesive tapes is preferably 500 gf or less, given that adhesive tapes or labels that are applied as antireflective layers of image displays are preferably easily stripped. More preferably 300 gf or less, even more preferably 100 gf or less, which is measured with a tensile tester. In order to ensure scratch resistance, the low refractive index sublayer preferably has a surface hardness of at least 0.3 Gpa, more preferably at least 0.5 Gpa, which is measured with a micro hardness tester.

The fluoropolymer provides crosslinking force with the perfluoroalkyl-containing silane compound (eg, heptadecafluoro-1,1,2,2-tetrahydrodecyl) triethoxysilane) and the fluoromonomer units. Hydrolysis of the fluorine-containing copolymer comprising monomer units followed by dehydration condensation.

Examples of fluoromonomers include fluoroolefins (eg, fluoroethylene, vinylidene fluoride, tetrafluoroethylene, perfluorooctylethylene, hexafluoropropylene, and perfluoro-2,2-dimethyl- 1,3-dioxol) and (meth) acrylic acid ("(meth) acrylic acid", which is a partially or fully fluorinated alkyl ester derivative, represent acrylic acid and / or methacrylic acid, the same below) (e.g., Osaka Organic Viscoat 6FM manufactured by Chemical Industry, Ltd. and M-2000 manufactured by Daikin Industries, Ltd.) and partially or fully fluorinated vinyl ethers. Perfluoroolefins are preferred. Hexafluoropropylene is particularly preferable in terms of its refractive index, solubility, transparency, and utility.

Monomers for providing crosslinking capacity include glycidyl (meth) acrylates (“(meth) acrylates” refer to acrylates and / or methacrylates, the same below) and self- such as glycidyl vinyl ethers. Derived from monomers having crosslinking functionality; Carboxyl, hydroxyl groups such as (meth) acrylic acid, methrol (meth) acrylate, hydroxyalkyl (meth) acrylate, allyl acrylate, hydroxyethyl vinyl ether, hydroxybutyl vinyl ether, maleic acid, and crotonic acid Derived from a monomer comprising an amino group or a sulfo group; And crosslinking functional groups (e.g., (meth) acryloyl groups) via polymer reactions (e.g. by mixing acryloyl groups to hydroxyl groups to form acrylic acid chlorides). It includes those produced by mixing in the monomer.

The fluorine-containing copolymer may further include a fluorine-removing monomer unit in order to improve solvent solubility and transparency, in addition to the fluoromonomer unit and the unit providing the crosslinking force. Such additional monomers include, but are not limited to, olefins (eg ethylene, propylene, isoprene, vinyl chloride, and vinylidene chloride), acrylic esters (eg methyl acrylate, ethyl acrylate, And 2-ethylhexyl acrylate), methacrylate esters (eg methyl methacrylate, ethyl methacrylate, butyl methacrylate, and ethylene glycol dimethacrylate), styrene derivatives (eg styrene, Divinylbenzene, vinyltoluene, and α-methylstyrene), vinyl ethers (eg methyl vinyl ether, ethyl vinyl ether, and cyclohexyl vinyl ether), vinyl esters (eg vinyl acetate, vinyl propionate , And vinyl cinnamates), acrylamides (eg, Nt-butylacrylamide and N-cyclohexylacrylamide), methacrylamide, and arc And a casting reel Ronnie derivative.

Curing agents may be appropriately added to the polymers described above, as disclosed in JP-A-10-25388 and JP-A-10-147739.

The light scattering sublayer is provided for hardcoat properties to improve surface scattering and / or internal scattering and scratch resistance. Thus, the light scattering sublayer includes a binder for developing hard coat properties, a mat particle for developing light scattering properties, and an inorganic filler, if desired, to improve refractive index, prevent shrinkage upon crosslinking, and increase strength. do. The light scattering sublayer also functions as an antiglare layer to provide a polarizing plate having an antiglare layer.

The light scattering sublayer preferably has a thickness of 1 to 10 µm, more preferably 1.2 to 6 µm, in order to secure hard coat properties. Too small a thickness will result in unsatisfactory hardness. Too thick layers tend to have poor processability, such as curls and brittleness.

The binder of the light scattering sublayer is preferably a polymer having a saturated hydrocarbon backbone or a polyether backbone, more preferably a polymer having a saturated hydrocarbon backbone. The binder polymer preferably has a crosslinked structure. The binder polymer having a saturated hydrocarbon backbone is preferably a polymer of ethylenically unsaturated monomers. The binder polymer having a saturated hydrocarbon backbone and crosslinked structure preferably comprises a homo- or copolymer of monomers comprising at least two ethylene-unsaturated groups. Such monomers may have one or more atoms selected from aromatic rings or halogen atoms other than fluorine, sulfur atoms, phosphorus atoms and nitrogen atoms to provide binder polymers with increased refractive index.

Examples of monomers containing two or more ethylenically unsaturated groups include ethylene glycol di (meth) acrylate, butanediol di (meth) acrylate, hexanediol di (meth) acrylate, 1,4-cyclohexane diacrylate, pentaerythritol Tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimetholpropane tri (meth) acrylate, trimetholethane tri (meth) acrylate, dipentaerythritol tetra (meth) acrylate, Dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, pentaerythritol hexa (meth) acrylate, 1,2,3-cyclohexane tetramethacrylate, polyurethane polyacrylate And esters of polyhydric alcohols and (meth) acrylic acids, such as polyester polyacrylates; Ethylene oxidation-modified products of the esters; Vinylbenzenes and derivatives thereof such as 1,4-divinylbenzene, 2-acryloylethyl 4-vinylbenzoate, and 1,4-divinylcyclohexanone; Vinylsulfones (eg divinylsulfone), acrylamides (eg methylenebisacrylamide); And methacrylamide. These monomers can be applied in combination of two or more.

Monomers that provide high refractive index include bis (4-methacryloylthiophenyl) sulfide, vinylnaphthalene, vinyl phenyl sulfide, and 4-methacryloxyphenyl-4'-methoxyphenyl thioether. These monomers can also be applied as a combination of two or more.

Polymerization of the ethylenically unsaturated group-containing monomer can be carried out by applying ion irradiation or heating in the presence of a radical photoinitiator or radical thermal initiator. Thus, the light scattering sublayer is applied to the protective film by applying a coating mixture comprising ethylenically unsaturated group-containing monomers, radical photoinitiators or thermal initiators, mat particles, and inorganic fillers and curing the coating layer by radiation-induced or heat-induced polymerization. Is formed. Known radical photoinitiators and radical thermal initiators can be used.

The polymer having a polyether backbone is preferably a ring-opening polymer of a polyfunctional epoxy compound. The ring-opening polymerization of the polyfunctional epoxy compound is carried out by applying ion irradiation or heating in the presence of a photo-acid generator or a heat acid generator. Thus, the light scattering sublayer applies a coating mixture of a multifunctional epoxy compound, a photo-acid generator or a thermal acid generator, a mat particle, and an inorganic filler to the protective film, and the coating layer is subjected to ion irradiation-induced polymerization or heat-induced polymerization. It can form by hardening.

The monomer mixture may include a monomer having a crosslinking functional group in place of or in addition to a monomer having two or more ethylenically unsaturated groups, thereby introducing a crosslinking structure into the binder polymer by reaction of the crosslinking functional group.

Examples of crosslinking functional groups include isocyanate groups, epoxy groups, aziridine groups, oxazoline groups, aldehyde groups, carbonyl groups, hydrazine groups, carboxyl groups, methirol groups, and active methylene groups. In addition, monomers capable of introducing crosslinking structures include metal alkoxides such as vinyl sulfonic acid, acid anhydrides, cyanoacrylate derivatives, melamines, etherified metyrols, esters, urethanes, and tetramethoxysilanes. Like block isocyanate groups, functional groups that decompose to develop crosslinking forces are also useful. That is, the crosslinking functional groups mentioned herein include groups that are not only reaction-prepared but also decompose to be ready for crosslinking. Binder polymers, including those such as crosslinking functional groups, form a crosslinked structure when heated after the coating mixture is applied.

The mat particles used in the light scattering sublayers for imparting antiglare properties are larger than the filler particles, and usually have an average particle size of 1 to 10 탆, preferably 1.5 to 70 탆. The mat particles include inorganic compound particles and resin particles.

Examples of mat particles include particles of inorganic compounds such as silica and titanium dioxide, and resin particles such as acrylic resins, crosslinked acrylic resins, polystyrenes, crosslinked polystyrenes, melamine resins, and benzoguanamine resins. Preferred among them are particles of crosslinked styrene, crosslinked acrylic resin, crosslinked acrylic styrene resin, and silica. The shape of the mat particles may be spherical or irregular.

Two or more kinds of mat particles having different particle sizes may be used in combination. For example, large particles may contribute to non-glare and small particles may contribute to other optical properties.

It is preferred that the mat particles have a single-dispersion particle size distribution. That is, the mat particles are preferably as similar in particle diameter as possible. Particles that are at least 20% larger than the median particle size are considered to be large particles, and the proportion of such large particles among all particles is preferably at most 1%, more preferably at most 0.1%, even more preferably at most 0.1%. Matt particles with a small size distribution are produced by classifying the particles as synthesized in a general manner. Higher number of classifications and / or higher degree of classification narrows the size distribution and becomes more desirable as a result.

The mat particles are preferably used in the light scattering sublayer in an amount of 10 to 1000 mg / m 2, more preferably 100 to 700 mg / m 2.

The particle size distribution of the mat particles is measured with a Coulter counter. The measured distribution is converted to a numeric distribution.

In order to increase the refractive index of the light scattering sublayer, the light scattering sublayer is preferably an inorganic filler such as titanium, zirconium, which has a median particle size of 0.2 μm or less, more preferably 0.1 μm or less, even more preferably 0.06 μm or less. Metal oxides of at least one of aluminum, indium, zinc, tin and antimony.

Where matt particles having a high refractive index are used, it is a desirable treatment to use silicon oxide as a filler to help reversely reduce the refractive index of the light scattering sublayer, whereby the refractive index difference from the matt particles is increased. The above preference for the particle size of the inorganic filler applies to the silicon oxide particles.

Examples of inorganic fillers useful for the light scattering sublayers include TiO ₂ , ZrO ₂ , Al ₂ O ₃ , In ₂ O ₃ , ZnO, SnO ₂ , Sb ₂ O ₃ , ITO, and SiO ₂ . TiO ₂ and ZrO ₂ are preferred for increasing the refractive index. The inorganic filler may be surface treated with a silane coupling agent or a titanium coupling agent to introduce functional groups that react with the binder species.

The amount of the inorganic filler is preferably 10 to 90%, more preferably 20 to 80%, and even more preferably 30 to 75%, based on the total weight of the light scattering sublayer. The fillers of the listed particle size are small enough to be compared to the light wavelength and consequently do not cause light scattering. Such filler dispersion systems in binder polymers act like optical single components.

The bulk refractive index of the binder and the inorganic filler mixture in the light scattering sublayer is preferably 1.50 to 2.00, more preferably 1.51 to 1.80, which can be achieved by appropriately selecting the type and ratio of the binder and the inorganic filler. The choice is simply made experimentally.

The coating mixture for forming the light scattering sublayer may comprise fluorine-containing surfactants and / or silicone surface active agents to prevent coating irregularities, dry irregularities and point defects and thereby ensure film uniformity. Fluorine-containing surface active agents are preferred for their ability to reduce coating irregularities, dry irregularities, point defects and similar coating defects with reduced amounts of addition. By the use of surface active agents, coating defects are reduced, which allows for high speed coating and thus improves productivity.

As described above, the antireflective layer may have a structure composed of one or more intermediate refractive index sublayers, a high refractive index sublayer, and a low refractive index sublayer. The intermediate refractive index sublayer is closest to the protective film and the low refractive index sublayer is at the outermost.

The antireflection layer having such a layer structure is designed to satisfy the following relation: refractive index of the high refractive index sublayer> refractive index of the intermediate refractive index sublayer> refractive index of the protective film> refractive index of the low refractive index sublayer. The hard coat sublayer may be provided between the protective film and the intermediate refractive index sublayer. On the other hand, a hard coat sublayer may be provided between the intermediate refractive index sublayer and the high refractive index sublayer. Antireflective layer structures applicable in the present invention are, for example, JP-A-8-122504, JP-A-8-110401, JP-A-10-300902, JP-A-2002-243906, and JP-A- 2002-111706.

Each sublayer may have additional functionality. For example, the low refractive index sublayer may be given anti-staining property, or the high refractive index sublayer may be given antistatic property. In detail, reference may be made to JP-A-10-206603 and JP-A-2002-243906.

The antireflective layer preferably has a pencil hardness of 5% or less, more preferably 3% or less, and preferably has a pencil hardness of at least H, more preferably at least 2H, even more preferably at least 3H, and is measured by JIS K5400.

The intermediate refractive index sublayer and the high refractive index sublayer are cured films containing a binder as a matrix and one or more inorganic compound particles having a high refractive index and a median particle size of 100 nm or less, respectively.

Inorganic compounds having a high refractive index include those having a refractive index of at least 1.65, preferably those having a refractive index of at least 1.9, such as oxides or composite oxides of Ti, Zn, Sb, Sn, Zr, Ce, Ta, La In and the like.

Such high refractive fine particles include, for example, silane coupling agents (see JP-A-11-295503, JP-A-11-153703, and JP-A-2000-9908), anionic compounds or organometallic coupling agents ( Surface treatment agents such as JP-A-2001-310432), which can be obtained by surface treatment of particles; By forming a center / shell structure having high refractive index particles as the center (see JP-A-2001-166104); Or by using specific dispersants (see JP-A-11-153703, US Pat. No. 6,210,858, and JP-A-2002-277609).

The matrix-forming binder includes known thermoplastic resins and known cured resins. The binder preferably comprises a component containing a multifunctional compound having at least two radically polymerizable groups and / or a cationic polymerizable group, a component containing an organometallic compound having a hydrolyzable group or a partial condensation product thereof, and Mixtures. Examples of these compounds are described in JP-A-2000-47004, JP-A-2000-315242, JP-A-2001-31871, and JP-A-2001-296401.

Cured films obtained from constructs containing colloidal metal oxides and metal alkoxides prepared by condensation of metal alkoxides following hydrolysis are also preferred matrices. The film is described, for example, in JP-A-2001-293818.

The high refractive index sublayer preferably has a refractive index of 1.70 to 2.20, preferably 5 nm to 10 μm, more preferably 10 nm to 1 μm.

The refractive index of the intermediate refractive index sublayer is adjusted to be between the refractive index of the low refractive index sublayer (hereafter listed) and the high refractive index sublayer. The intermediate refractive index sublayer preferably has a refractive index of 1.50 to 1.70, preferably 5 nm to 10 μm, more preferably 10 nm to 1 μm.

The low refractive index sublayer formed on the high refractive index sublayer preferably has a refractive index of 1.20 to 1.55, more preferably 1.30 to 1.50.

The low refractive index sublayer is preferably designed as scratch-resistant and stain resistant outer sublayer. Imparting slip properties to the surface is an effective way to greatly improve the scratch resistance, which can be achieved by applying known thin film techniques using silicon compounds or fluorine-containing compounds.

The fluorine-containing compound preferably comprises a crosslinking functional group or a polymerizable functional group and has a fluorine content of 35 to 80% by weight. Examples of fluorine-containing compounds are JP-A-9-222503, paragraphs [0018]-[0026], JP-A-11-38202, paragraphs [0019]-[0003], and JP-A-2001-40284 , Paragraphs [0027]-[0028], and JP-A-2000-284102. The fluorine-containing compound is preferably 1.35 to 1.50, more preferably 1.36 to 1.47.

Silicone compounds are polysiloxane compounds which preferably contain curable functional groups or polymerizable functional groups in the polymer chain to form a crosslinked structure in the film. Examples include reactive silicones (Silaplane available from Chisso Corp.) and polysiloxanes having salanol groups at both ends (see JP-A-11-258403).

The low refractive index sublayer comprising a fluorine-containing polymer or silicone is a coating composed of a fluorine-containing compound or a polysiloxane compound including a crosslinkable group or a polymerizable group, a polymerization initiator, a sensitizer, etc., in a high refractive index sublayer or the like. It is preferably formed by applying the mixture and applying light or heat to the coating layer simultaneously with or after the coating.

Preference is also given to films which are formed by a condensation curing reaction and solidified with a sol-gel between an organometallic compound such as a silane coupling agent in the presence of a catalyst and a silane coupling agent comprising a specific hydrofluoric hydrocarbon group. Examples of the latter silane coupling agents are polyfluoroalkyl-containing silane compounds or partial hydrolysis-condensation products thereof, in particular JP-A-58-142958, JP-A-58-147483, JP-A-58-147484, The compounds described in JP-A-9-157582, and JP-A-11-106704; And silyl compounds having perfluoroalkyl ether groups (ie, fluorine-containing long chains), such as those described in JP-A-2000-117902, JP-A-2001-48590, and JP-A-2002-53804 It includes.

In addition to the components described above, the low refractive index sublayer may contain other additives such as fillers, silane coupling agents, slip agents, and surface active agents. Examples of useful fillers are particles of inorganic compounds having low refractive indices such as silicon dioxide (silica) and fluorine-containing compounds (e.g. magnesium fluoride, calcium fluoride, and barium fluoride) and average primary particle sizes of 1-150 nm. And the fine organic particles described in JP-A-11-3820, paragraphs [0020] to [0038].

If a low refractive index sublayer is provided next to the outer layer, the low refractive index sublayer may be formed by vapor phase treatment such as vacuum evaporation, sputtering, ion plating or plasma-assisted CVD. Nevertheless, wet coating methods are preferred from an economic point of view.

The low refractive index sublayer preferably has a thickness of 30-200 nm, more preferably 50-150 nm, even more preferably 60-120 nm.

The hard coat layer is provided on the protective film having an antireflection layer in order to provide physical strength to the protective film. It is preferably provided between the transparent substrate and the high refractive index sublayer. The hard coat layer is preferably formed by crosslinking or polymerization of the photo-curing or heat-curing compound. The curing functional group of the curing compound is preferably a photopolymerizable functional group. Preference is also given to organometallic compounds comprising hydrolysable functional groups or organic alkoxysilyl compounds. Useful compounds are the same as listed for the high refractive index sublayer.

Examples of useful mixtures for forming the hard coat layer are provided in JP-A-2002-144913, JP-A-2000-9908, and WO00 / 46617.

The high refractive index sublayer can serve as a hard coat layer. In this case, it is preferable to form a hard coat layer by precisely dispersing the fine particles using the technique described for the high refractive index sublayer.

The hard coat layer may contain particles having an average particle size of 0.2 to 10 μm in order to serve as an antiglare layer having an antiglare function.

The thickness of the hard coat layer can be appropriately designed according to the purpose. The thickness of the hard coat layer is preferably in the range of 0.2 to 10 m, more preferably 0.5 to 7 m.

The hard coat layer preferably has a pencil hardness of at least H, more preferably at least 2H, even more preferably at least 3H, which is measured by JIS K5400. Moreover, the hardcoat layer preferably has as little taber wear as possible in the taber wear test specified in JIS K5400.

In addition to the antireflection layer, the polarizing plate of the present invention may have a forward scattering layer, a primer layer, an antistatic layer, a bottom coating layer, a protective sheet, and the like.

Where an antistatic layer is provided, it is desirable to impart electrical conductivity expressed by volume resistivity of 10 ⁻⁸ (Ωcm ⁻³ ) or less. Although the volume resistivity is reduced to 10 ⁻⁸ (Ωcm ⁻³ ) or less using hygroscopic substances, water soluble inorganic salts, certain surface active agents, cationic polymers, anionic polymers, colloidal silica, etc., the resulting layer The volume resistance is severely dependent on temperature and humidity, and as a result, it is impossible to ensure sufficient conductivity under low humidity conditions. Therefore, it is reasonable to use metal oxide as the antistatic layer material. Colored metal oxides are undesirable because they color the entire film. It is advisable to use an unpainted metal oxide composed mainly of one or more of Zn, Ti, Sn, Al, In, Si, Mg, Ba, Bo, W and V. Examples of suitable metal oxides include ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , In ₂ O ₃ , SiO ₂ , MgO, BaO, MoO ₃ , WO ₃ , V ₂ O ₅ , and composite oxides thereof. In particular, ZnO, TiO ₂ , and SnO ₂ are preferred. The metal oxide may be doped with hetero atoms. Effective metal oxides doped with hetero atoms include ZnO doped with Al or In, SnO ₂ doped with Sb, Nb or halogen atoms, and TiO ₂ doped with Nb or Ta. As described in JP-B-59-6235, particulate or fibrous crystalline metals (eg titanium oxide) having the metal oxide attached thereto are also useful. Unlike the physical properties, the volume resistance and the surface resistance are not easily compared, but when the antistatic layer has a surface resistance of about 10 ⁻¹⁰ (Ω / square) or less, preferably 10 ⁻⁸ (Ω / square) or less, 10 ⁻ A volume resistance of ⁸ (Ωcm ^-3 ) or less will be secured. The surface resistance of the antistatic layer should be measured while the antistatic layer is on the outermost side. That is, the surface resistance measurement of the antistatic layer is performed in the process of forming the laminated structure.

The LCD according to the present invention has an LCD (first embodiment) using the polarizing plate according to the present invention, and VA mode, OCB mode or TN having two polarizing plates according to the present invention, one on the viewer side and the other on the backlight side. A mode LCD (second embodiment) and a VA mode LCD (third embodiment) having one polarizing plate according to the present invention on the side of the backlight.

The polarizing plate of the present invention is advantageously applied to LCD. The polarizing plate of the present invention can be applied to a wide range of LCD display modes. Proposed LCD display modes include twisted nematic (TN), in-plane swtiching (IPS), ferroelectric liquid crystal (FLC), anti-ferroelectric liquid crystal (AFLC), optically compensatory bend (OCB), supper twisted nematic (STN), Vertically aligned (VA), and hybrid aligned nematic (HAN). Among these modes, VA mode and OCB mode are preferable for applying the polarizing plate of the present invention.

In the VA mode liquid crystal cell, when no voltage is applied, the rod-shaped liquid crystal molecules are arranged substantially vertically. The VA mode liquid crystal cell is (1) a VA mode liquid crystal cell in a narrow sense in which rod-shaped liquid crystal molecules are arranged substantially vertically when voltage is not applied and are substantially horizontal when voltage is applied (see JP-A-2-176625). (2) MVA mode liquid crystal cell (described in SID97, Digest of tech. Papers, 28 (1997), p. 845), in which VA mode is transformed into a multi-domain in order to secure a viewing angle. Nippon Ekisho Toronkai, Digest of tech. Papers (1998), in which the rod-shaped liquid crystal molecules are arranged substantially vertically and arranged in a substantially twisted multi-domain orientation upon application of voltage. pp. 58-59), and (4) a liquid crystal cell in SURVIVAL mode (disclosed in LCD international 98).

The VA mode LCD includes a liquid crystal cell (VA mode cell) and two polarizing plates each composed of TAC1, polarizer and TAC2, as shown in FIG. 2, one polarizing plate is disposed on the side of the viewer and the other One is arranged on the side of the backlight. The liquid crystal cell holds a liquid crystal between two electrodes.

In the OCB mode liquid crystal cell, the rod-shaped liquid crystal molecules are arranged in a band state so that the molecules on one side of the cell and the molecules on the other side are arranged in substantially opposite directions (symmetrically). OCB mode liquid crystal cells are disclosed in US Pat. Nos. 4,583,825 and 5,410,422. Since the arrangement of rod-like liquid crystal molecules is symmetrical on both sides of the cell, the band-array cell has a self-compensating function. This is why the band arrangement mode is called "optical compensation band" mode. Band array mode LCDs have the advantage of improved response times.

In another embodiment of the transmissive LCD according to the present invention, a particular cellulose acylate film is applied as a protective film provided between the liquid crystal cell and the polarizer. The cellulose acylate film is either a protective film of only one polarizing plate (cellulose acylate film disposed between the cell and the polarizer) or a protective film of both polarizing plates (cellulose acylate film disposed between the cell and the polarizer of each polarizing plate) Is applicable. The polarizing plate is preferably attached to the liquid crystal cell such that the specific cellulose acylate film (ie, TAC1) specified in the present invention contacts the VA mode liquid crystal cell. When a particular cellulose acylate film is used as a protective film of one of the polarizing plates (disposed between the cell and the polarizer), there is no functional difference whether the polarizing plate is disposed on the viewer side or the backlight side. When a polarizing plate having a specific cellulose acylate film on the liquid crystal cell side is disposed on the viewer side of the cell, the polarizing plate must have a functional layer formed on the outer side (viewer side), which can reduce the production yield. In this respect, a polarizing plate having a specific cellulose acylate film is preferably applied to the backlight side of the liquid crystal cell.

In the second embodiment of the LCD, the polarizing plate of the present invention is applied to both sides of the liquid crystal cell. In the third embodiment of the LCD, the polarizing plate of the present invention is applied only to the backlight side of the liquid crystal cell.

The protective film (TAC2) may be a specific cellulose acylate film embodied in the present invention or a cellulose acylate film employed in the prior art. Cellulose acylate films usable with TAC2 include, but are not limited to, KC4UX2M (thickness: 40 μm), KC5UX (thickness: 60 μm) and KC80UXSFD (thickness: 80 μm) all available from Konica Opto Corp .; And both TD80U (thickness: 80 μm) and TF80U (thickness: 80 μm) available from Fuji Photo Film Co., Ltd.

Example

Although the present invention will be described in more detail with reference to examples, it is obvious that the invention is not to be construed as being limited thereto. Although not described, all parts, percentages, and ratios are by weight.

1. Preparation of cellulose acylate film (film numbers 1 to 19)

1-1. Synthesis of Cellulose Acylate

In each degree of substitution shown in Table 1, the cellulose acylate having an acyl group shown in Table 1 was prepared by acylation of 100 parts of cellulose with carboxylic acid in the presence of 7.8 parts of sulfuric acid as a catalyst at 40 ° C. The kind of acyl group and the degree of substitution by the acyl group in the resulting cellulose acylate are determined by the selection of the type and amount of the corresponding carboxylic acid. After acylation, the reaction system is aged at 40 ° C. and then washed with acetone to remove low molecular weight components. In Table 1, CTA is a cellulose triacetate (acyl group: acetyl); CTB represents cellulose acetate butyrate (acyl group: acetyl + butyryl): and CAP represents cellulose acetate propionate (acyl group: acetyl + propionyl).

To dichloromethane / methanol mixed solvent (87/13), as shown in Table 1, cellulose acylate, plasticizer (triphenyl phosphate (TPP) and biphenyldiphenyl phosphate (BDP)), and other additives (shown below) UV absorbers 1 and 2 and retardation enhancers 1 and 2) are poured and stirred during heating to produce a solution having a cellulose acylate concentration of 15%. At the same time, 0.05 parts of AEROSIL R972 (manufactured by Nippon Aerosil Co., LTD.) As a mat agent are poured into the mixture and stirred under heating. In Table 1, the amounts of plasticizer system and additives (%) are based on the weight of cellulose acylate.

UV Absorbent 1 (abbreviated to UV-1 in Table 1):

UV absorbers 2 (abbreviated to UV-2 in Table 1):

Retardation Enhancer 1 (abbreviated as RD-1 in Table 1):

Retardation Enhancer 2 (abbreviated as RD-2 in Table 1):

1-2. casting

The resulting dope is cast on the band by the use of band casting equipment. The semi-dried casting film with a residual solvent content of 25-35% is peeled off from the band and applied to the tenter at a draw ratio of 10 to 30.5% (see Table 1) at a temperature of about (Tg-10) to (Tg + 10) ° C. It is stretched in the lateral direction.

The Tg of the cellulose acylate film is a dynamic viscoelasticity measuring instrument (Vibron DVA-225 manufactured by ITK Co., Ltd.) at a heating rate of 2 ° C./min from 30 ° C. to 200 ° C., at a sample length between 20 mm grips. , And at a frequency of 1 Hz. The storage modulus is plotted on a logarithmic coordinate with the log longitudinal axis and temperature (° C.). Line 1 (solid region) and line 2 (glass transition region) are shown which show a sharp decrease in storage modulus observed in the phase transition from the solid region to the glass transition region. The intersection of lines 1 and 2 represents the temperature at which the storage modulus begins to decrease rapidly and the temperature at which the film begins to soften, ie the temperature at which the film begins to change into the glass transition region. This temperature is called the glass transition temperature Tg (dynamic viscoelastic). The Tg of all the cellulose acylate films prepared in the examples was measured by the method described above and is in the range of 110 to 160 ° C.

After setting at 25 ° C. and 60% RH for 2 hours, each of the resulting cellulose acylate films (compensation film) 1-19 was available from Oji Scientific Instruments at 590 nm, 25 ° C. and 60% RH, respectively. Measure the retardation values (Re and Rth) with. The results obtained are shown in Table 3.

All cellulose acylate films prepared in Example 1 had a haze of 0.1-0.9, showed a 0-3% mass change at 80 ° C. and 90% RH for 48 hours, and no more than 50 × 10 ⁻¹³ cm 2 / dyne Had a photoelastic coefficient of. The mat agent used in the cellulose acylate film had an average secondary particle size of 1.0 μm or less.

2. Preparation of protective film with optically anisotropic layer (film number 20 ~ 23)

2-1. Protective film with optically anisotropic layer (film numbers 20 and 21)

Cellulose acylate films (film numbers 20 and 21 shown in Table 1) prepared in the same manner as films No. 1 to 19, respectively, were coated with 5.2 ml / m 2 of saponification solution having the following constitution, and at 60 ° C. for 10 seconds. To dry. The film surface is washed with running water for 10 seconds and dried by blowing air at 25 ° C.

Composition of saponification solution:

Isopropyl Alcohol 818 Part

Water 167 parts

Propylene Glycol 187 Parts

Potassium Hydroxide 68 Part

Surfactant (nC ₁₆ H ₃₃ O (C ₂ H ₄ O) ₁₀ H) 12 parts

The coating mixture having the following formulation was applied to the saponified surface of cellulose acylate film 20 or 21 using a # 14 wire bar coater at a coating rate of 24 ml / m 2 and dried for 60 seconds with hot air at 60 ° C. Then dried at 90 ° C. for 150 seconds to form an alignment layer. The alignment layer was rubbed in the direction of 45 ° (substantially coincident with the low axis) from the stretching direction of the cellulose acetate film 20 or 21.

Formulation of coating mixture for alignment layer:

Modified polyvinyl alcohol (1) 20 parts

Water 360 parts

Methanol 120 Parts

Glutaraldehyde (Crosslinker) 1.0 Part

Modified Polyvinyl Alcohol (1):

The alignment layer is coated at 25 ° C. with a # 3.6 wire bar coater at 6.2 ml / m 2 of a mixture having the following formulation to form an optically anisotropic layer.

Formulation of coating mixture of optically anisotropic layer:

Discotic liquid crystal compound formula:

                                                    91 parts

Ethylene Oxide-Modified Trimetholpropane Triacrylate (V # 36, manufactured by Osaka Organic Chemistry Industry, Ltd.) 9 parts

Cellulose acetate butyrate (CAB531-1 manufactured from Eastman Chemical Co.) 1.5 parts

Photopolymerization Initiator (Irgacure 807 from Ciba Geigy, Ltd.)

                                                      3 parts

Photosensitizer (Kayacure DETX manufactured by Nippon Kayaku Co., Ltd.)

                                                      1 part

Citrix mixed ester formula:

R: H or C ₂ H ₅ 1.0 parts

Methyl Ethyl Ketone 214.2 Part

The coated film is held on a metal frame and heated for 2 minutes in a thermostat at 140 ° C. to arrange the discotic liquid crystal molecules. The film was then irradiated for 1 minute at 90 ° C. with UV light from a 120 W / cm high pressure mercury lamp to polymerize the discotic liquid crystal molecules, and then at room temperature to obtain a protective film (film numbers 20 and 21) with an optically anisotropic layer. Cool slowly

Table 1-continued

2-2. Protective film with optically anisotropic layer (film number 22)

The nematic liquid crystal compound and the chiral agent, both shown below, were mixed to exhibit selective reflectivity at 290-310 nm, and a photopolymerization initiator was added to prepare a cholesteric liquid crystal solution. The solution was applied to a biaxially stretched PET film to induce crosslinking to form a retardation layer B having a thickness of 1.9 μm, Re of 2 nm, and Rth of 132 nm, and heated at 80 ° C. for 3 minutes. , Was irradiated with UV light. The retardation layer B was attached to a commercially available cellulose acylate film (TAC TD80U, manufactured by Fuji Photo Film Co., Ltd.) through a 15 μm thick acrylic adhesive layer. The biaxially stretched PET film was stripped to provide a laminated retarder (film no. 22) with 2 nm Re and 182 nm R.

Nematic liquid crystal compound:

Chiralases:

2-3. Protective film with optically anisotropic layer (film number 23)

Polyhexamide synthesized from 2,2'-bis (3,4-dicarboxyphenyl) hexafluoropropane and 2,2'-bis (trifluoromethyl) -4,4'-diaminobiphenyl Dissolve in rice fields to prepare a 15% solution. The polyimide solution was applied to a 80 μm thick TAC base film (TAC TD80U, manufactured by Fuji Photo Film) and dried at 120 ° C. for 10 minutes to form a laminate composed of a TAC base film and a 5 μm thick non-liquid crystalline polymer film. Get The laminate was stretched 1.05 times in the transverse direction using a tenter to obtain a protective film (film number 23) laminated with an optically anisotropic layer having a total thickness of 73 μm. The film thus formed is a laminated film of the stretched TAC film as the optical compensation layer and the stretched non-liquid crystalline polymer layer as the optical compensation layer.

3. Preparation of protective film with antireflection function (film numbers 24 and 25)

3-1. Protective film with antireflection function (film number 24)

(a) Preparation of Coating Mixture for Light Scattering Sublayers

A 50 g weight pentaerythritol triacrylate / pentaerythritol tetraacrylate mixture (PETA, manufactured by Nippon Kayaku) is diluted in 38.5 g of toluene. 2 g of polymerization initiator (Irgacure 184, manufactured by Ciba Specialty Chemicals) are added to the solution and dissolved by stirring. The coating film obtained by UV-curing the solution had a refractive index of 1.51.

Separately, crosslinked polystyrene particles (SX-350, manufactured by Soken Chemical & Engineering Co., Ltd .; refractive index: 1.60) having an average particle size of 3.5 μm were applied for 20 minutes at 10000 rpm in a Polytron dispersion apparatus. Dispersed in toluene to produce 30% dispersion-1. A 30% toluene dispersion-2 of crosslinked acrylic styrene particles (Soken Chemical &Engineering; Refractive Index: 1.55) having an average particle size of 3.5 μm was prepared simultaneously.

The monomer solution prepared above was added to 1.7 g of dispersion-1 and 13.3 g of dispersion-2. Finally, 0.75 g of fluorine-containing surface modifier (FP-1) and 10 g of silane coupling agent (KBM-5103, manufactured by Shin-Etsu Chemical Co., Ltd.) were added. The mixture is filtered through a polypropylene filter having an opening size of 30 μm to prepare a coating mixture of light scattering sublayers.

(b) Preparation of Coating Mixture for Low Refractive Index Sublayers

A reactor equipped with a stirrer and a circulation condenser was equipped with 120 parts of methyl ethyl ketone, 100 parts of acryloyloxypropyltrimethoxysilane (KBM5103, manufactured by Shin-Etsu Chemical), and 3 parts of diisopropoxy (ethyl acetoacene). Taito) aluminum was poured and mixed. 30 parts of ion-exchanged water was added to the mixture, and the mixture was allowed to react at 60 ° C. for 4 hours, and then cooled to room temperature to obtain a sol solution-a. The weight average molecular weight was 1600 and 100% of the oligomer and polymer components had a molecular weight of 1,000 to 20,000. Gas chromatography analysis showed no residue of starting acryloyloxypropyltrimethoxysilane.

13 g thermal crosslinkable fluoropolymer having a refractive index of 1.42 (JN-7228, manufactured by JSR Corp .; solid content: 6%), 1.3 g silica sol (MEK-ST of different sizes, Nissan Chemical Industries, Ltd .; average Particles: 45 nm; solids: 30%), a mixture of 0.6 g sol solution-a, 5 g methyl ethyl ketone, and 0.6 g cyclohexanone was stirred and filtered through a polypropylene filter having an opening size of 1 μm A coating mixture for the refractive index sublayer is prepared.

(c) Preparation of protective film with antireflection layer

30 rpm gravure rotation speed and 30 m using a 50 mm diameter micro gravure roll and doctor blade with an 80 μm thick triacetyl cellulose film (TAC TD80U, manufactured by Fuji Photo Film) and a gravure pattern with 180 lines and 40 μm deep Coated with a coating mixture for the functional layer (light scattering sublayer) at a film running speed of / min, dried at 60 ° C. for 150 seconds, and 160 W / cm air-cooled metal halide in an atmosphere purged with nitrogen to cure the coating layer. Using a lamp (manufactured by Eye Graphics Co., Ltd.) with UV light at a power density of 400 mW / cm 2 and a dose of 250 ml / cm 2, a light scattering sublayer having a thickness of 6 μm was formed. The film with the light scattering sublayer is once wound on a roll.

The film with the light scattering sublayer was released. The coating mixture for the low refractive index sublayer was prepared using a 50 mm diameter micro gravure roll with a gravure pattern of 180 lines and a depth of 40 μm and a doctor bleed at 30 rpm gravure rotation speed and film progression speed of 15 m / min. Apply to the side of the layer, dry at 120 ° C. for 150 seconds, then at 140 ° C. for 8 minutes, use a 240 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.) in an atmosphere purged with nitrogen Irradiated with UV light at a power density of 400 mW / cm 2 and a dose of 900 ml / cm 2 to form a low refractive index sublayer having a thickness of 100 μm. The film is wound on a roll to produce a protective film having an antireflection function (film number 24).

3-2. Protective film with antireflection function (film number 25)

(a) Preparation of Coating Mixture for Hard Coat Sublayer

To 750.0 parts of trimethylolpropane triacetate (TMPTA, manufactured by Nippon Kayaku Co., Ltd.), 270.0 parts of polyglycidyl methacrylate having a weight average molecular weight of 3000, 730.0 g of methyl ethyl ketone, 500.0 g Cyclohexanone and 50.0 g of a photopolymerization initiator (Irgacure 184, manufactured by Ciba Geigy, Japan) were added and stirred. The mixture was filtered through a polypropylene filter having an opening size of 0.4 μm to prepare a coating mixture for the hard coat sublayer.

(b) Preparation of Titanium Dioxide Dispersion

To 257.1 g of titanium dioxide particles containing cobalt and surface treated with aluminum hydroxide and zirconium hydroxide (MPT-129, manufactured by Ishihara Sangyo Kaisha, Ltd.), 38.6 g of dispersant and 704.3 g of cyclohexanone shown below The mixture was added and dispersed in Dynomill to prepare a titanium dioxide dispersion having a weight average particle size of 70 nm.

Dispersant:

(c) Preparation of the Coating Mixture for the Medium Refractive Index Sublayer

To 88.9 g of titanium dioxide dispersion prepared above, 58.4 g of dipentaerythritol pentaacrylate / dipentaerythritol hexaacrylate mixture (DPHA, manufactured by Nippon Kayaku), 3.1 g of photopolymerization initiator (Irgacure 907, Ciba- Geigy Japan Ltd.), 1.1 g of a photosensitizer (Kayacure DETX, manufactured by Nippon Kayaku), 482.4 g of methyl ethyl ketone, and 1869.8 g of cyclohexanone were added. The mixture was stirred thoroughly and filtered through a polypropylene filter with an opening size of 0.4 μm to prepare a coating mixture of medium refractive index sublayers.

(d) Preparation of coating mixture for high refractive index sublayer

In 586.8 g of titanium dioxide dispersion prepared above, 47.9 g of dipentaerythritol pentaacrylate / dipentaerythritol hexaacrylate mixture (DPHA, manufactured by Nippon Kayaku), 4.0 g of photopolymerization initiator (Irgacure 907, Ciba- Geigy Japan Ltd.), 1.3 g photosensitive agent (Kayacure DETX, manufactured by Nippon Kayaku), 455.8 g methyl ethyl ketone, and 1427.8 g cyclocyclo were added. The mixture was stirred and filtered through a polypropylene filter having an opening size of 0.4 μm to prepare a coating mixture of high refractive index sublayers.

(e) Preparation of Coating Mixture for Low Refractive Index Sublayers

The copolymer (P-1) shown below was dissolved in methyl isobutyl ketone at a concentration of 7%, and a silicone resin (X-22-164C manufactured by Shin-Etsu Chemical) and an optical radical generator (Irgacure) having a methacrylate group at the end thereof. 907) was added to the solution in amounts of 3% and 5%, respectively, based on the solids amount of the solution, to prepare a coating mixture for the low refractive index sublayer.

Copolymer (P-1):

(Polymerization ratio: per mole)

(f) Preparation of a transparent protective film having an antireflection layer

An 80 μm thick triacetyl cellulose film (TAC TD80U, manufactured by Fuji Photo Film) was coated with a gravure coater with a coating mixture for the hard coat sublayer. The coating layer was dried at 100 ° C. and irradiated with UV light at a power density of 400 mW / cm 2 and a dose of 300 J / cm 2 using a 160 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics) while purging the atmosphere with nitrogen. The oxygen concentration was adjusted to 1.0 vol% or less. As a result, the coating layer was cured to form a hard coat sublayer having a thickness of 8 μm.

A gravure coater with three coating stations was used on the hardcoat sublayers to apply the coating mixture for the medium refractive index sublayer, the coating mixture for the high refractive index sublayer, and the coating mixture for the low refractive index sublayer.

Medium refractive index sublayer drying conditions were 100 ° C. and 2 minutes. UV irradiation was carried out with a power density of 400 mW / cm 2 and a dose of 400 J / cm 2 using a 180 W / cm 2 air-cooled metal halide lamp (manufactured by Eye Graphics) while purging the atmosphere, adjusting the oxygen concentration to 1.0 vol% or less. did. The intermediate refractive index sublayer thus formed had a refractive index of 1.630 and a thickness of 67 nm.

Drying conditions for the high refractive index sublayer and the low refractive index sublayer are 1 minute at 90 ° C, followed by 1 minute at 100 ° C. UV irradiation for the formation of both the high and low refractive index sublayers purged the atmosphere while using a 240 W / cm 2 air-cooled metal halide lamp (manufactured by Eye Graphics) with a power density of 600 mW / cm 2 and a dose of 600 mJ / cm 2 The oxygen concentration was adjusted to 1.0 vol% or less. After curing, the high refractive index sublayer had a refractive index of 1.905 and a thickness of 107 nm, and the low refractive index sublayer had a refractive index of 1.440 and a thickness of 85 nm. This gives a transparent protective film (film number 25) with an antireflection layer.

Example 1

1. Preparation of Polarizing Plate 1

A 75 μm thick PVA film with a degree of polymerization of 2400 was swelled in 30 ° C. water for 40 seconds. The swelled PVA film was immersed in an aqueous solution containing 0.06% iodine and 6% potassium iodide at 30 ° C. for 60 seconds and then in an aqueous solution containing 4% boric acid and 3% potassium iodide at 40 ° C. for 60 seconds. Supported. While the PVA film is loaded, it is stretched 5.2 folds along its long axis. Immediately before stretching, the water content of the PVA film was 52%. The PVA film stretched to the next major axis was stretched 1.1 layers transversely using the tenter. As a result, the last length was five times the original length. The stretched film was dried at 50 ° C. for 4 minutes to obtain a polarizer (referred to as polarizer 1).

Film 1 (prepared cellulose acylate film) and commercially available triacetyl cellulose film (TAC TD80U, manufactured by Fuji Photo Film) were each immersed in an aqueous solution of 1.5 mol / L sodium hydroxide for saponification and to remove sodium hydroxide. Rinse thoroughly with water. The film was then immersed in a 0.005 mol / L diluted sulfuric acid aqueous solution at 35 ° C. for 1 minute, immersed in water to completely remove the diluted sulfuric acid aqueous solution, and dried well at 120 ° C.

Polarizer 1 was sandwiched between saponified cellulose acylate film 1 and saponified TD80U film through a polyvinyl alcohol adhesive and heated at 70 ° C. for 30 minutes. Three centimeters were trimmed from the edges using a cutter to produce a roll-shaped polarizing plate 1 having an effective width of 1200 mm and a length of 50 m.

Sheets 39 cm wide and 65 cm long were cut into the appropriate portions of the polarizing plate 1, and the in-plane phase difference Rpva was measured at 1 cm intervals using a near infrared phase difference measuring system KOBRA-WX100 / IR (manufactured by Oji Scientific Instruments). did. One of the cut sheets (polarizer 1) had a maximum Rpva of 973.0 nm and a minimum Rpva of 945.0 nm with a deviation of 3.0%. The maximum-minimum Rpva deviation of all other cut sheets was in the range of 3.0% or less. For all cut sheets, the maximum deviation in Rpva measured at 1 cm intervals was 6 nm / cm (see Table 3).

2. Preparation of polarizing plates 2 to 23 and polarizing plates 27 to 30

The polarizing plates 2 to 23 and the polarizing plates 27 to 30 were prepared by the same method as the polarizing plate 1 except for the combination of a cellulose acylate film compatible with a previously prepared protective film (film numbers 2 to 25), as shown in Table 3. It became. The film thickness and degree of polymerization of the PVA film applied for producing the polarizer, the conditions for producing the polarizer, and the like are shown in Table 2.

A plurality of sheets cut to a width of 39 cm and a length of 65 cm for each of the polarizing plates were tested in the same manner as in the polarizing plate 1. Table 3 shows the maximum Rpva, the minimum Rpva, the deviation between the maximum and the minimum, the maximum deviation of Rpva per centimeter of the cut sheet that showed the largest maximum-minimum deviation of all sheets cut from the same polarizer.

Commercially available cellulose acylate films applied to polarizing plates were TAC TF80U and TAC TD80U, manufactured by Fuji Photo Film, and KC80UVSFD, manufactured by Konica Opto Corp.

All polarizers and two protective films are provided in roll form and are laminated and associated together in a continuous manner parallel to each other in the major axis direction. The cellulose acylate films 1 to 19 applied as the protective film of the polarizer on the side of the liquid crystal cell had a slow axis parallel to the transmission axis of the polarizer. In the same way that the slow axis of the transparent substrate and the transmission axis of the polarizer are parallel to each other, the protective films 20 to 23 having the optically anisotropic layer are attached to one side of the polarizer on the transparent substrate with polyvinyl alcohol.

3. Preparation of Polarizer 31

The polarizing plate is produced by the same method described above, except that the commercially available cellulose acylate film TD80U (manufactured by Fuji Photo Film) is applied to both sides of the polarizer (see polarizing plate number 31 shown in Table 3). A 25 μm thick acrylic adhesive layer was applied to one side of the polarizing plate, and a 90 μm thick film, which will be described later, was attached thereto to obtain a polarizing plate 31. The stretched film is prepared by stretching a 100 μm thick norbornene resin film (ARTON, manufactured by JSR Corp.) in a transverse direction using a tenter, and from the refractive index measured by a phase measurement system KOBRA 21ADH (manufactured by Oji Scientific Instruments). It had a calculated 95 nm of Re and 50 nm of Rth.

An acrylic adhesive was applied to the cell-face side of polarizer 31 and a separate film was attached to the adhesive. The protective sheet was attached on the opposite side.

Comparative Example 1

Preparation of Polarizing Plates 24-26:

Polarizing plates 24-26 were produced in the same manner as in Example 1 except that the swelling step was not performed prior to dyeing and that the PVA film was uniaxially stretched with an unfixed width rather than biaxially stretched. The combination of protective films is shown in Table 3.

Table 2-Continued

Table 2-Continued

Table 3-continued

Table 3-continued

Refractive Index Measurement:

Spectrophotometric reflectance at 5 ° incidence angle on the side of the functional layer of the polarizer, with a spectrophotometer (manufactured by JASCO Corp.) equipped to obtain integrated sphere-average reflectivity in the wavelength range of 450-650 nm. It was measured in the wavelength range of. Polarizers 7 and 13 with film 27, which are transparent protective films with antireflective layers, have an average reflectivity of 0.4%, while polarizers 4 and 12 with film 26, which are transparent protective films with antireflective layers, have an average reflectance of 2.3%. Has Prior to the measurement, the protective sheet on the transparent protective film having the antireflective layer was stripped.

Example 2

LCD-TV in VA mode (LC-30AD1, manufactured by Sharp Corp.) was stripped of the polarizing plates on the viewing side and the backlight side, and instead of the polarizing plate and viewing angle compensation film prepared in Example 1 according to the combination shown in Table 4 A polarizing plate selected from a commercially available polarizing plate (HLC2-5618, manufactured by Sanritzu Corp.) was provided. The polarizing plate on the viewing side was arranged such that its absorption axis was parallel to the horizontal direction of the LCD panel, and the polarizing plate on the backlight side was arranged so that its absorption axis coincided with the vertical direction of the panel. The polarizer was attached to the side of the adhesive facing the liquid crystal cell.

After the peelable protective sheet has been stripped, the viewing angle of the LCD-TV (angle that provides a contrast ratio of 10 or more without gradient reversal on the black display) has a contrast meter (EZContrast 160D, manufactured by ELDIM) with black (L1) Measured at 8 scales from to the white (L8) display. LCD-TV showed satisfactory viewing angle characteristics with any polarizer tested.

An LCD-TV (screen size: 30 inches (about 39 cm × 65 cm)) assembled as described above using the polarizing plate of Example 1 was evaluated for screen image uniformity with backlight light and was graded as follows. lost. The results obtained are shown in Table 4.

Screen image uniformity rating:

AA: Very good.

A: Weak streaked spots look closer.

B: Striped stains were observed.

C: Streaked spots are clearly observed.

Comparative Example 2

Each of the polarizing plates 24 to 26 manufactured in Comparative Example 1 was attached to the VA mode LCD panel in the same manner as in Example 2, and the viewing angle characteristics and the screen image uniformity were evaluated in the same manner as in Example 2. The results obtained are shown in Table 4. Any comparative polarizer was inferior to the polarizer according to the present invention in terms of viewing angle compensation performance and screen image uniformity, and the screen portion was dark and not good.

Example 3

A polyimide film was formed on a pair of glass substrates having an ITO electrode rubbed as an alignment layer. The two organic substrates were bonded so that the alignment layers faced each other and the two alignment layers were parallel to each other, thereby forming a cell having a cell gap of 5.7 μm. The cell was filled with a liquid crystal compound (ZLI1132, manufactured by Merck Ltd.) having a Δn of 0.1396 in order to form a 30 inch (about 39 cm × 65 cm) liquid crystal cell with a band alignment.

The pair of polarizing plates 27 or the pair of polarizing plates 28 prepared in Example 1 have a liquid crystal cell such that the optically anisotropic layer faces the cell substrate and the rubbing direction of the optically anisotropic layer facing the rubbing direction of the cell is parallel and opposite to each other. It was attached to both sides of the.

The LCD was observed when the backlight was turned on. It has been proved that the LCD using the polarizing plate according to the present invention showed a small change in contrast and color along with the viewing angle.

Furthermore, the same LCD panel was evaluated for image uniformity according to the following grading system. The results are shown in Table 5.

Screen image uniformity rating:

AA: Very good.

A: Weak streaked spots look closer.

B: Striped stains were observed.

C: Streaked spots are clearly observed.

Comparative Example 3

Each of the polarizing plates 24 to 26 manufactured in Comparative Example 1 was disposed on the liquid crystal cell in the same manner as in Example 3. After the peelable protective sheet is stripped, the viewing angle of the LCD-TV (angle providing a contrast ratio of 10 or more without tilting inversion on the black display) has a contrast meter (EZContrast 160D, manufactured by ELDIM) and black (L1) to white (L8). ) Measured at 8 scale up to the display. All comparative polarizers were inferior to the polarizers according to the present invention in terms of viewing angle compensation performance and screen image uniformity, and the screen portion was dark and was not good.

This application is based on Japanese Patent Application JP 2004-276108, filed September 22, 2004, the entire contents of which are incorporated by reference as described in detail.

Claims (16)

A polarizing plate having a polarizer containing polyvinyl alcohol and a protective film provided on at least one side of the polarizer, And wherein the polarizer has a deviation of 5.0% or less between the maximum and minimum values of its in-plane retardation Rpva in any region having a width of 39 cm and a length of 65 cm. The method of claim 1, The deviation of said in-plane phase difference Rpva between any two points 1 cm apart is 10 nm or less. The method of claim 1, The polarizer is manufactured by a process comprising swelling a polyvinyl alcohol film and stretching the swelled polyvinyl alcohol, The stretching step is a step of stretching in a biaxial, polarizing plate. The method of claim 1, The protective film provided on one side of the polarizer has a front retardation value Re (590) and a thickness direction retardation value Rth (590), and all at 590 nm wavelengths, the following equations (1) and Equation (2): 20nm≤Re (590) ≤200nm (1) 70nm≤Rth (590) ≤400nm (2) To satisfy the polarizer. The method of claim 4, wherein The protective film provided on one side of the polarizer has a ratio of Re (590) to Rth (590) of 0.1 ~ 0.8, the polarizing plate. The method of claim 1, The protective film provided on one side of the polarizer includes, as a main polymer component, a cellulose acyl containing a cellulose mixed fatty acid ester having an acyl group and an acetyl group containing three or more carbon atoms to substitute a hydroxyl group of cellulose. It is a late film, The cellulose mixed fatty acid ester is represented by the following formula (3) and formula (4): 2.0≤A + B≤3.0 (3) 0 <B (4) Satisfying Where A is the degree of substitution by the acetyl group; B is a degree of substitution by an acyl group having 3 or more carbon atoms. The method of claim 6, The acyl group having three or more carbon atoms is a butanoyl group. The method of claim 6, The acyl group having three or more carbon atoms is a propionyl group. The method of claim 1, The protective film provided on one side of the polarizer is a cellulose acylate film having an acyl group containing two or more carbon atoms, the following formula (5) and formula (6): 2.0≤DS2 + DS3 + DS6≤3.0 (5) DS6 / (DS2 + DS3 + DS6) ≥0.315 (6) Satisfying Wherein DS2, DS3 and DS6 each represent a degree of substitution of hydroxyl groups at 2-, 3- and 6-positions of the glucose units constituting cellulose by the acyl groups. The method of claim 9, The acyl group is an acetyl group, polarizing plate. The method of claim 1, The protective film provided on one side of the polarizer includes at least one of a plasticizer, an ultraviolet absorber, a release agent, a dye, and a matting agent. The method of claim 1, The protective film provided on one side of the polarizer comprises at least one retardation enhancer selected from rod-shaped compound and discotic compound (discotic compound), the polarizing plate. The method of claim 1, The protective film provided on one side of the polarizer comprises a polymer film and an optically anisotropic layer, polarizing plate. The method of claim 1, And at least one of a hard coat layer, an antiglare layer, and an antireflection layer on a protective film disposed on the other side of the polarizer. The method of claim 1, The polarizing plate further comprises a retardation film attached via an adhesive to the protective film provided on one side of the polarizer.  It includes a liquid crystal cell and a polarizing plate, The polarizing plate is a polarizing plate according to claim 1, wherein the protective film on one side of the polarized light faces the liquid crystal cell.

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