KR20140015540A - Elongated polarization plate and liquid crystal display device - Google Patents

Abstract

An elongate polarizing plate having an absorption axis in the width direction and easy to rework is provided. Further, a liquid crystal display device in which luminance unevenness at the time of black display is improved is provided. The elongate polarizing plate of this invention is an elongate polarizing plate in which at least a transparent protective film, a polarizer, and an optical compensation film are laminated | stacked in this order, The said polarizer has an absorption axis in the width direction, and the Nz coefficient of the said polarizer Is within the range of 1.05 to 1.20, and the film thickness d of the optical compensation film is within a range that satisfies the following formula (1).
Equation (1): 10 μm <d <40 μm

Description

Long shape polarizer and liquid crystal display {ELONGATED POLARIZATION PLATE AND LIQUID CRYSTAL DISPLAY DEVICE}

The present invention relates to an elongate polarizing plate and a liquid crystal display device provided with the elongate polarizing plate.

The cost reduction of a liquid crystal display device is calculated | required. As the method, there is a method of reducing the loss of the polarizing plate. The liquid crystal display device requires two polarizing plates orthogonal to the viewer side and the backlight side. Display devices, especially televisions and monitors, differ in length from side to side of the screen. Therefore, when it is going to cut out from the elongate polarizing plate which has an absorption axis in the longitudinal direction which is normally used, the size of one side was limited to the length of the width of a polarizing plate, and it could not respond to enlargement. Moreover, the acquisition efficiency was also bad.

As a method of improving the problem, in addition to a polarizing plate having an absorption axis in the normal longitudinal direction, a polarizing plate having an absorption axis in the width direction of one sheet may be produced, and a method of cutting out orthogonal polarizing plates for the viewing side and the backlight side from each of them may be considered. Can be. There exists a technique disclosed by patent document 1 as an example of preparation of the polarizing plate which has an absorption axis in the width direction. Here, the optical film which improves the dispersion | variation in the polarization degree in the both ends of the fabric width direction which becomes a problem when manufacturing the polarizing plate which has an absorption axis in the width direction, and obtains the outstanding optical characteristic when used for a liquid crystal panel is disclosed.

However, although the optical performance as a polarizing plate was evaluated in the said patent document 1, it does not mention about evaluation when it is actually used on a panel.

On the other hand, by improving the front contrast of the current liquid crystal panel, the luminance unevenness at the time of small black display which has not been a problem until now becomes outstanding, and the luminance unevenness which cannot be improved even by the technique disclosed by the said patent document 1 becomes a problem. have.

In addition, when the bonding of the polarizing plate to the cell fails for cost reduction, a rework is required to remove the polarizing plate from the cell in order to reuse the liquid crystal cell.If the optical compensation film used for the polarizing plate is thin, the polarizing plate is torn or broken. There is also a problem that peeling residues are generated on the cells, making it difficult to rework.

Japanese Patent Laid-Open No. 2010-26112

This invention is made | formed in view of the said problem and the situation, and the subject of solution is providing the elongate polarizing plate which has an absorption axis in the width direction, and is easy to rework. Furthermore, the present invention provides a liquid crystal display device in which luminance unevenness at the time of black display is improved.

The said subject which concerns on this invention is solved by the following means.

1. An elongate at least transparent elongated protective film, a polarizer and an optical compensation film are elongated polarizing plates formed by laminating in this order, wherein the polarizer has an absorption axis in the width direction, and the Nz coefficient of the polarizer is in the range of 1.05 to 1.20. It exists in the inside, and the film thickness (d) of the said optical compensation film exists in the range which satisfy | fills following formula (1), The elongate shape polarizing plate characterized by the above-mentioned.

Equation (1): 10 μm <d <40 μm

2. It is a liquid crystal display device which has a backlight, a liquid crystal cell, and a polarizing plate one by one on the viewing side and a backlight side of the said liquid crystal cell at least, The polarizing plate obtained by cutting the elongate polarizing plate of 1 is provided, and also The liquid crystal display device characterized by satisfying the requirements (a) to (c).

(a) As the polarizing plate (hereinafter referred to as "polarizing plate 1") on the backlight side of the liquid crystal cell, the optical compensation film (hereinafter referred to as "optical compensation film 1") of the polarizing plate obtained by cutting the elongate polarizing plate according to the above 1 It is arrange | positioned so that it may become the said liquid crystal cell side.

(b) The polarizing plate (hereinafter referred to as "polarizing plate 2") on the visual side of the liquid crystal cell is a polarizing plate in which a transparent protective film, a polarizer and an optical compensation film (hereinafter referred to as "optical compensation film 2") are laminated in this order. It is arrange | positioned so that the said optical compensation film 2 may be the said liquid crystal cell side.

(c) It arrange | positions so that the absorption axis of the said polarizing plate 1 and the said polarizing plate 2 may orthogonally cross.

3. The said liquid crystal cell is a vertically-aligned liquid crystal cell, the said optical compensation film 2 contains the cellulose ester in which the average acyl group substitution degree exists in the range of 2.0-2.6, and also the following formula (2)-a formula ( The relationship represented by 5) is satisfied. The liquid crystal display device according to 2 above.

Equation (2): Ro (1) ≤ 5 nm

Equation (3): -10 nm < Rt (1) &lt; 20 nm

Equation (4): 60nm≤Ro (2) ≤80nm

Equation (5): 190nm≤Rt (2) ≤260nm

(However, in-plane retardation values Ro measured at a measurement wavelength of 589 nm at 23 ° C. and 55% RH of the optical compensation film 1 and the optical compensation film 2 are referred to as Ro (1) and Ro (2), respectively. In addition, thickness direction retardation value Rt is called Rt (1) and Rt (2), respectively, and Ro and Rt are defined by a following formula.

Formula (I): Ro = (n _x -n _y ) × d (nm)

Formula (II): Rt = {(n _x + n _y ) / 2-n _z } × d (nm)

In said formula, Ro represents the in-plane phase difference value in an optical compensation film (also called phase difference film), and Rt represents the phase difference of the thickness direction in a film. In addition, d represents the thickness of an optical compensation film, and n _x represents the refractive index of the largest (ground-axis direction) in surface of an optical compensation film. n _y represents the refractive index of the direction orthogonal to the slow axis in the optical compensation film plane, and n _z represents the refractive index of the optical compensation film in the thickness direction. In addition, measurement conditions are as above.)

4. A reflective luminance improving film is provided between the backlight and the polarizing plate 1, and the transmission axis of the reflective luminance improving film and the absorption axis of the polarizer of the polarizing plate 1 are arranged so as to be perpendicular to each other. The liquid crystal display device according to 2 or 3 above.

By the said means of this invention, the elongate polarizing plate which has an absorption axis in the width direction and is easy to rework can be provided. In addition, a liquid crystal display device having improved luminance unevenness at the time of black display can be provided.

According to the said means of this invention, even when the absorption axis of a polarizer is made into the width direction, when the Nz coefficient of a polarizer is in the range of 1.05-1.20, entanglement of the polymer in a polarizer is maintained, the film intensity | strength of a polarizer rises, and the laminated optical Even when the compensation film is a thin film, no crack is generated in the polarizing plate at the time of rework, and no peeling residue is generated.

Moreover, when the Nz coefficient of the polarizer of a backlight side polarizing plate exists in the range of 1.05-1.20, when it is incorporated in a vertically-aligned liquid crystal display device, contrast can be improved, but luminance unevenness is in a practical range.

1 is a conceptual diagram illustrating an example of a liquid crystal display of the present invention.

The elongate polarizing plate of this invention is an elongate polarizing plate in which at least a transparent protective film, a polarizer, and an optical compensation film are laminated | stacked in this order, The said polarizer has an absorption axis in the width direction, and the Nz coefficient of the said polarizer Is within the range of 1.05 to 1.20, and the film thickness d of the optical compensation film is within a range that satisfies the formula (1): 10 탆 <d <40 탆. This feature is a technical feature common to the inventions relating to the claims 1 to 4.

The elongate polarizing plate of this invention can be used suitably for a liquid crystal display device. In particular, it is a liquid crystal display device which has at least one backlight, a liquid crystal cell, and a polarizing plate one by one on the visual side and the backlight side of the said liquid crystal cell, and the polarizing plate obtained by cutting the elongate polarizing plate of this invention is provided, and also the said requirement It can use suitably for the liquid crystal display device of the form which satisfy | fills (a)-(c). In this case, the said liquid crystal cell is a vertically-aligned liquid crystal cell, the said optical compensation film 2 contains the cellulose ester in which the average acyl-group substitution degree exists in the range of 2.0-2.6, and said Formula (2)-Formula It is preferable that the relationship represented by (5) is satisfied. Moreover, the liquid crystal display device of the form in which a reflective luminance improvement film is provided between the said backlight and the polarizing plate 1, and arrange | positioned so that the transmission axis of the said reflective luminance improvement film and the absorption axis of the polarizer of the said polarizing plate 1 orthogonally crosses. Preference is given to (see FIG. 1).

EMBODIMENT OF THE INVENTION Hereinafter, the detailed content and form for implementing this invention, its component, and this invention are demonstrated. In addition, in this application, "-" uses the numerical value described before and after that by the meaning included as a lower limit and an upper limit.

(Summary of Long Shape Polarizing Plate of the Present Invention)

The elongate polarizing plate of this invention is an elongate polarizing plate in which at least a transparent protective film, a polarizer, and an optical compensation film are laminated | stacked in this order, The said polarizer has an absorption axis in the width direction, and the Nz coefficient of the said polarizer Is within the range of 1.05 to 1.20, and the film thickness d of the optical compensation film is within a range that satisfies the following formula (1).

Equation (1): 10 μm <d <40 μm

In addition, in this application, "long shape" means the film shape which has a length of 500 m or more. In addition, what cut | disconnected the rectangle of predetermined dimension from the roll of the said elongate polarizing plate is called "sheet-shaped polarizing plate."

(Polarizer)

As for the elongate polarizer which concerns on this invention, it is preferable that Nz coefficient defined by following formula (i) is 1.05 <Nz <1.20, More preferably, it is 1.05 <Nz <1.15. If it is 1.05 or less, the rework property will be inferior, and if it is 1.20 or more, the light leakage of the black display at the time of using it on a panel will be too large, and it will not be able to display it as black.

Formula (i) Nz = (n _x -n _z ) / (n _x -n _y )

(Wherein n _x is the refractive index in the slow axis direction in the film plane, n _y is the refractive index in the fast axis direction in the film plane, and n _z is the refractive index in the thickness direction of the film)

In addition, in this application, a "polarizer (also called a" polarizing film ")" means the film | membrane (film) which has a function which transmits only the linearly polarized light which has a specific vibration direction.

The refractive indexes n _x , n _y , n _z of the polarizer can be measured using an automatic birefringence meter. For example, using KOBRA-WX100 / IR (manufactured by Oji Keisukuki Co., Ltd.), the wavelength can be obtained at 1000 nm under an environment of a temperature of 23 ° C. and a humidity of 55% RH.

As the polarizer, any suitable polarizer may be employed depending on the purpose. For example, a dichroic substance such as iodine or a dichroic dye is adsorbed onto hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized polyvinyl alcohol films, and ethylene / vinyl acetate copolymerized partial saponified films. The polyene type orientation film, such as the thing extended | stretched and stretched, the dehydration process of polyvinyl alcohol, and the dehydrochlorination process of polyvinyl chloride, etc. are mentioned. Among these, the polarizer which adsorbed and extended | stretched dichroic substances, such as iodine, on the polyvinyl alcohol-type film has a high polarization dichroic ratio, and is especially preferable. Although the thickness in particular of these polarizers is not restrict | limited, It is preferable that it is about 5-80 micrometers.

A polarizer stretched by adsorbing iodine on a polyvinyl alcohol-based film can be produced by, for example, dyeing polyvinyl alcohol by dipping in an aqueous solution of iodine and stretching the film to 3 to 7 times its original length. Boric acid, zinc sulfate, zinc chloride, etc. may be included as needed, and it can also be immersed in aqueous solutions, such as potassium iodide. If necessary, the polyvinyl alcohol film may be dipped in water and washed with water before dyeing.

By washing the polyvinyl alcohol-based film with water, it is possible not only to wash the contamination and blocking blocking agent on the surface of the polyvinyl alcohol-based film, but also to swell the polyvinyl alcohol-based film to prevent irregularities such as staining of dyeing. Stretching may be performed after dyeing with iodine, stretching while dyeing, or stretching, followed by dyeing with iodine. It can extend | stretch also in aqueous solution, such as boric acid and potassium iodide, or in a water bath.

(Polarizer)

In this application, a "polarizing plate" means the optical film in which a transparent protective film, a polarizer, and an optical compensation film are laminated | stacked in this order. In addition, depending on a case, it may use with the meaning containing an elongate (roll-shaped) polarizing plate and a sheet-shaped polarizing plate.

The polarizing plate of the present invention can be produced by a general method. With a transparent protective film and an optical compensation film, it is preferable to join together to form the both surfaces of the polarizer produced by immersion extending | stretching in the iodine solution. Examples of the adhesive for bonding include a PVA adhesive, a urethane adhesive, a UV curable adhesive, and the like.

When bonding the transparent protective film and optical compensation film which concern on this invention to a polarizer, it is preferable to perform a hydrophilization process and a corona treatment as an adhesion | attachment facilitation process to the surface of the said film before that. Examples of the hydrophilization treatment include saponification treatment, plasma treatment, flame treatment and ultraviolet irradiation treatment. The saponification treatment includes an acid saponification treatment and an alkali saponification treatment. In the present invention, an alkali saponification treatment is preferably used.

It is preferable to perform an alkali saponification process by the method of directly immersing the said film in the tank of saponification liquid, or the method of apply | coating a saponification liquid to a cellulose acylate film. As a coating method, the dip coating method, the curtain coating method, the extrusion coating method, the bar coating method, and the E-type coating method can be proposed. In order to apply | coat the solvent of an alkali saponification process coating liquid to a transparent support body of a saponification liquid, it is wettability, and the solvent which maintains a planar shape in good state, without forming unevenness | corrugation on the transparent support surface by a saponification liquid solvent It is desirable to choose. Specifically, an alcoholic solvent is preferable and isopropyl alcohol is especially preferable. Moreover, the aqueous solution of surfactant can also be used as a solvent. The alkali which melt | dissolves in the said solvent is preferable, and, as for the alkali of an alkali saponification coating liquid, KOH and NaOH are more preferable. The pH of the saponifying coating liquid is preferably 10 or more, more preferably 12 or more. 1 second-5 minutes are preferable at room temperature, as for the reaction conditions at the time of alkali saponification, 5 second-5 minutes are more preferable, 20 second-3 minutes are especially preferable. After the alkaline saponification reaction, it is preferable to wash the saponified liquid coated surface with water or acid and then wash with water.

In the present invention, the surface of the film can be processed before bonding with the polarizer according to the individual requirements of the protective film or the optical compensation film to improve the performance. As such a surface treatment, For example, as a process which prevents surface reflection and improves the visibility of a liquid crystal panel, it is an antiglare process, a nonglare process, or an anti-reflective process; Antistatic or antifouling treatments to reduce fouling adhesion of surfaces; Hard coating treatments that improve mechanical properties to increase surface hardness and improve solvent resistance and chemical resistance; The coloring process for giving a desired color, etc. are mentioned. Such treatment can be carried out by a known method depending on the purpose. You may superimpose several surface treatments.

[Optical Compensation Film 1]

The elongate polarizing plate of this invention is an elongate polarizing plate in which an elongate transparent protective film, a polarizer, and an optical compensation film are laminated | stacked in this order, The film thickness (d) of the said optical compensation film is represented by following formula (1) It is characterized by being in a satisfying range.

Equation (1): 10 μm <d <40 μm

The in-plane retardation value Ro measured in the measurement wavelength of 589 nm at 23 degreeC * 55% RH of the said optical compensation film exists in the range of 0-10 nm, and thickness direction retardation value Rt is -20-45 nm. It is preferable to exist in the range of.

In addition, when using the said optical compensation film for the liquid crystal display device which has a backlight, a liquid crystal cell, and a polarizing plate one by one on the viewing side and backlight side of the said liquid crystal cell, for example, the polarizing plate of the backlight side of the said liquid crystal cell ( Hereinafter, as "polarizing plate 1", it is preferable that the optical compensation film (henceforth "optical compensation film 1") of the polarizing plate obtained by cutting the said elongate polarizing plate is arrange | positioned so that it may become the said liquid crystal cell side.

In addition, the in-plane retardation value Ro measured by the measurement wavelength of 589 nm at 23 degreeC * 55% RH of the said optical compensation film 1 is called Ro (1), and thickness direction retardation value Rt is Rt (1). In this case, it is preferable to satisfy the following formulas (2) and (3).

Equation (2): Ro (1) ≤ 5 nm

Equation (3): -10 nm < Rt (1) &lt; 20 nm

In addition, Ro and Rt are defined by the following formula.

Formula (I): Ro = (n _x -n _y ) × d (nm)

Formula (II): Rt = {(n _x + n _y ) / 2-n _z } × d (nm)

In said formula, Ro represents the in-plane phase difference value in an optical compensation film, and Rt represents the phase difference of the thickness direction in a film. In addition, d represents the thickness of an optical compensation film, and n _x represents the largest (ground-axis direction) refractive index in surface of an optical compensation film. n _y represents the refractive index of the direction orthogonal to the slow axis in the optical compensation film plane, and n _z represents the refractive index of the optical compensation film in the thickness direction. In addition, measurement conditions are the same as the above.

As resin used for the optical compensation film 1, a cellulose ester resin, an acrylic resin, cycloolefin resin, etc. are mentioned. Especially, it is preferable to contain an acrylic resin.

Methacrylic resin is also contained in the acrylic resin which can be used for the said optical compensation film. Although it does not restrict | limit especially as resin, What consists of 50-99 mass% of methylmethacrylate units and 1-50 mass% of other monomeric units copolymerizable with this is preferable.

Examples of other copolymerizable monomers include alkyl methacrylates having 2 to 18 carbon atoms for alkyl, alkyl acrylates having 1 to 18 carbon atoms for alkyl, alpha, beta -unsaturated acids such as acrylic acid and methacrylic acid, maleic acid, Aromatic vinyl compounds such as unsaturated group-containing divalent carboxylic acids such as fumaric acid and itaconic acid, styrene, α-methylstyrene, and nuclear substituted styrene, α, β-unsaturated nitriles such as acrylonitrile and methacrylonitrile, and maleic anhydride Acid, maleimide, N-substituted maleimide, glutaric anhydride, etc. are mentioned, These can be used individually or in combination of 2 or more types.

Among these, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate, etc. are preferable, and methyl acrylate and n-butyl acrylate are preferable. Particularly preferably.

As an acrylic resin, a commercially available thing can also be used. (Manufactured by Asahi Kasei Chemicals Corporation), Dianal BR52, BR80, BR83, BR85 and BR88 (manufactured by Mitsubishi Rayon Co., Ltd.) and KT75 (manufactured by Denki Kagaku Kogyo Co., Ltd.) And the like.

Moreover, in this invention, (meth) acrylic resin which has a lactone ring structure can also be used as an acrylic resin. As (meth) acrylic resin which has the said lactone ring structure, Unexamined-Japanese-Patent No. 2000-230016, Unexamined-Japanese-Patent No. 2001-151814, Unexamined-Japanese-Patent No. 2002-120326, Unexamined-Japanese-Patent No. 2002-254544 (Meth) acrylic resin which has a lactone ring structure as described in Unexamined-Japanese-Patent No. 2005-146084, etc. is mentioned.

Moreover, you may blend an acrylic resin with another resin. As another resin, it is preferable to use a cellulose ester resin together from a viewpoint of a physical property and heat resistance improvement. For example, it is preferable to contain an acrylic resin and a cellulose ester resin in the mass ratio of 95: 5-30: 70. Preferably, acrylic resin (A) is 50 mass% or more. In addition, the average acyl group substitution degree of the said cellulose ester resin is 2.00-3.00, the acetyl group substitution degree (ac) is 0-1.89, carbon number of acyl groups other than an acetyl group is 3-7, and a weight average molecular weight (Mw) is Preferred forms are 75000 to 280000.

[Optical Compensation Film 2]

When using the polarizing plate obtained by cutting the said elongate polarizing plate of this invention for a liquid crystal display device, For example, the liquid crystal display of a form which has a polarizing plate by a backlight, a liquid crystal cell, and the viewing side and the backlight side of the said liquid crystal cell, respectively, one by one. When used for the device, a polarizing plate (hereinafter referred to as "polarizer 2") on the visual side of the liquid crystal cell is laminated with a transparent protective film, a polarizer and an optical compensation film (hereinafter referred to as "optical compensation film 2") in this order. It is a polarizing plate formed, and it is preferable to arrange | position so that the said optical compensation film 2 may become the said liquid crystal cell side.

Moreover, it is preferable that the said optical compensation film 2 contains the cellulose ester. As a cellulose ester used for the said optical compensation film 2, average acyl-group substitution degree is 1.00-2.80 from a viewpoint of phase difference expression property, moisture resistance, etc., More preferably, it is 2.0-2.6.

Moreover, the cellulose ester which concerns on this invention is resin in which many (beta) -glucose molecules superposed | polymerized in linear form by (beta) -1, 4- glycoside bond. The glucose unit which comprises cellulose by the said β-1,4-glycosidic bond has the free hydroxyl group (hydroxyl group) in 2nd, 3rd, and 6th positions. Therefore, the cellulose-ester resin which concerns on this invention is a polymer (resin) which esterified one part or all part of these hydroxyl groups (hydroxyl group) by the acyl group.

"Acyl group substitution degree" shows the sum total of the ratio by which the hydroxyl group (hydroxyl group) is esterified about the 2nd, 3rd, and 6th positions of glucose of a repeating unit. Specifically, the case where the hydroxy group (hydroxyl group) in each of the second, third and sixth positions of cellulose is 100% esterified is referred to as substitution degree 1, respectively. Therefore, when all 2nd, 3rd, and 6th positions of cellulose are 100% esterified, substitution degree will be 3 maximum.

In this application, "average acyl-group substitution degree" means the acyl-group substitution degree which expressed the acyl-group substitution degree of the some glucose unit which comprises a cellulose ester as an average value per unit. In addition, in this application, the average value of substitution degree, such as a specific acyl group, for example, an acetyl group, a propionyl group, is abbreviate | omitted "average" like "acetyl group substitution degree", "propionyl group substitution degree", etc., respectively. I will express it.

The measuring method of acyl-group substitution degree can be measured according to ASTM-D817-96.

As an acyl group, for example, an acetyl group, propionyl group, butanoyl group, heptanoyl group, hexanoyl group, octanoyl group, decanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, hexadecanoyl group, octa Decanoyl group, isobutanoyl group, tert-butanoyl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like.

Among these, acetyl group, propionyl group, butanoyl group, dodecanoyl group, octadecanoyl group, tert-butanoyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like are more preferable, and particularly preferred. Is an acetyl group, a propionyl group, butanoyl group (when an acyl group has 2 to 4 carbon atoms), More preferably, it is an acetyl group.

Moreover, in the case of an aliphatic acyl group, 2-6 are preferable and, as for carbon number, from a viewpoint of the productivity and cost of cellulose synthesis | combination, 2-4 are more preferable. In addition, it is preferable that the part which is not substituted by the acyl group exists normally as a hydroxyl group (hydroxyl group).

In this invention, it is preferable that the said optical compensation film 2 is 60-80 nm of phase difference values Ro, and Rt is 190-260 nm especially when enlarging the viewing angle of a vertically-aligned liquid crystal display device. That is, it is preferable that the relationship represented by following formula (4) and (5) is satisfied.

Equation (4): 60nm≤Ro (2) ≤80nm

Equation (5): 190nm≤Rt (2) ≤260nm

(However, the in-plane retardation value Ro measured at a measurement wavelength of 589 nm at 23 ° C. and 55% RH of the optical compensation film 2 is called Ro (2), and the thickness direction retardation value Rt is Rt (2). In addition, Ro and Rt are defined by said Formula (I) and (II).

Although the film thickness (d) does not have a restriction | limiting in particular, Preferably it is 50-80 micrometers.

Moreover, it is preferable that the optical compensation film 2 contains the glucose compound mentioned later.

In order to obtain retardation value (retardation value) (Ro, Rt) aimed at by this invention, it is preferable that an optical compensation film takes the structure of this invention, and also performs refractive index control by control of conveyance tension and an extending | stretching operation. .

For example, it is possible to vary the phase difference value (retardation value) by lowering or increasing the tension in the longitudinal direction.

Moreover, biaxial stretching or uniaxial stretching can be performed in order or simultaneously with respect to the longitudinal direction (film forming direction) of a film, and the direction orthogonal to it in a film plane, ie, the width direction.

There is no particular limitation on the method of extending the web. For example, a method in which a plurality of rolls are placed in a circumferential speed and stretched in the longitudinal direction using a roll circumferential difference therebetween, both ends of the web are fixed with clips or pins, and the distance between the clips or pins is extended in the advancing direction. And stretching in the longitudinal direction, likewise extending in the horizontal direction and stretching in the horizontal direction, or stretching in both the longitudinal and horizontal directions at the same time. Of course, you may use these methods in combination.

In the so-called tenter method, it is preferable to drive the clip portion by the linear drive method, since smooth drawing can be performed and the risk of breakage can be reduced.

It is preferable to perform this width | variety maintenance or the extending | stretching of a horizontal direction of a film forming process with a tenter, and a pin tenter or a clip tenter may be sufficient.

When the slow axis or fast axis of the optical compensation film according to the present invention is present in the film plane, and the angle formed by the film forming direction is θ1, it is preferable that θ1 is -1 ° or more and + 1 ° or less, and -0.5 ° or more + It is more preferable that it is 0.5 degrees or less.

This (theta) 1 can be defined as an orientation angle, and measurement of (theta) 1 can be performed using automatic birefringence system cobra (KOBRA) -21ADH (Oji Keisukuki). θ1 satisfying the above relationship can contribute to obtaining high luminance in the display image, suppressing or preventing light leakage, and contributing to obtaining faithful color reproduction in the color liquid crystal display device.

[Transparent protective film 1]

As used herein, the term "transparent protective film" refers to a film that is a structural member of a polarizing plate and which is bonded to a polarizer and plays a role of suppressing dimensional change and physical property change of the polarizer. For example, resin films, such as a triacetyl cellulose (TAC) film, are generally used. The detail of the resin base material which can be used by this invention is mentioned later.

Moreover, as a transparent protective film, the optical film commercially available (for example, Konica Minolta Tak KC8UX, KC4UX, KC5UX, KC8UY, KC4UY, KC12UR, KC8UCR-3, KC8UCR-4, KC8UCR-5, KC8UE, KC4UE, KC4FR-3, KC4FR-4, KC4HR-1, KC8UY-HA, KC8UX-RHA, the above-mentioned Konica Minolta Advanced Layer Co., Ltd.), etc. are also preferably used.

As the cellulose ester resin used for the transparent protective film 1, the effect is remarkable when the average acyl group substitution degree is 2.70 to 3.00 from the viewpoint of preventing the film from shrinking even if the temperature rises and suppressing the occurrence of stains. Do. This is presumably because the cellulose ester resin of the acyl group substitution degree of this range is excellent in moisture resistance originally, and a remarkable effect is recognized.

Although the film thickness of the transparent protective film 1 does not have a restriction | limiting in particular, It is preferable that it is 10-40 micrometers.

[Transparent protective film 2]

As cellulose-ester resin used for the transparent protective film 2, it is as above-mentioned, and in order to have a protective function, average acyl-group substitution degree, Preferably it is 2.70-3.00.

Although the film thickness of a transparent protective film does not have a restriction | limiting in particular, It is preferable that it is 40-80 micrometers.

[Cellulose ester]

As a cellulose ester which can be used for the transparent protective film and optical compensation film which concern on this invention, the cellulose triacetate, a cellulose diacetate, a cellulose ester propionate etc. which can be used for a well-known optical film are mentioned.

The number average molecular weight (Mn) of a cellulose ester is preferable because the mechanical strength of the film from which the range of 30000-30000 is obtained is strong. And those of 50,000 to 200,000 are preferably used.

It is preferable that the value of ratio (Mw / Mn) of the weight average molecular weight (Mw) and number average molecular weight (Mn) of a cellulose ester is 1.4-3.0.

The number average molecular weight (Mn) and the weight average molecular weight (Mw) of cellulose ester were measured using gel permeation chromatography (GPC).

Measurement conditions are as follows.

Solvent: methylene chloride

Column: Shodex K806, K805, K803G (three manufactured by Showa Denko Co., Ltd. were used)

Column temperature: 25 ° C

Sample concentration: 0.1 mass%

Detector: RI Model 504 (manufactured by GL Science)

Pump: L6000 (manufactured by Hitachi Seisakusho Co., Ltd.)

Flow rate: 1.0 ml / min

Calibration curve: Standard curve of polystyrene STK standard A calibration curve with 13 samples of polystyrene (manufactured by Tosoh Corporation) Mw = 1000000 to 500 was used. 13 samples are used at almost equal intervals.

Although there is no limitation in particular as a cellulose of the raw material of a cellulose ester, Cotton linter, wood pulp (derived from hardwood, derived from hardwood), kenaf, etc. are mentioned. The cellulose esters obtained therefrom may be mixed and used in an arbitrary ratio.

The cellulose ester which concerns on this invention can be manufactured by a well-known method. Specifically, it can synthesize | combine with reference to the method of Unexamined-Japanese-Patent No. 10-45804, 2009-161701, etc. with reference.

Glucose Compounds

It is preferable that the optical compensation film which concerns on this invention, especially the said optical compensation film 2 contains a glucose compound. By adding a glucose compound to the optical compensation film, the glucose compound can act as a moisture modifier, making the film more likely to shrink.

In this invention, it is preferable to contain the compound represented by following General formula (I) as a glucose compound.

(I)

In the formula, each of R ¹¹ and R ¹² independently represents an alkyl group having 1 to 10 carbon atoms or an alkenyl group having 2 to 10 carbon atoms, and one CH ₂ group present in these groups or adjacent groups Two or more CH ₂ groups that are not present may be substituted with an oxygen atom (O), L ¹ represents —OCO— *, —OCH ₂ — * (bonds with B on the * side), or represents a single bond; Each independently represents a trans-1,4-cyclohexylene group or 1,4-phenylene group which may be substituted, and R ¹³ and R ¹⁴ each independently represent a hydrogen atom or a C 1-10 Acyl)

R ¹¹ and R ¹² are preferably each independently an alkyl group having 1 to 10 carbon atoms, an alkoxyl group, an alkoxyalkyl group or an alkenyl group having 2 to 10 carbon atoms. More preferably, they are a C1-C6 alkyl group, an alkoxy group, an alkoxyalkyl group, or a C2-5 alkenyl group. More preferably, they are ethyl group, n-propyl group, n-butyl group, n-pentyl group, methoxy group, ethoxy group, n-propoxy group, n-butoxy group or allyl group, Most preferably, it is a methoxy group . These R ¹¹ and R ¹² may be the same or different, respectively.

L ¹ represents -OCO- *, -OCH _2- * (bonded with B on the * side) or a single bond, and preferably -OCO- * or -OCH _2- *.

A and B each independently represent a trans-1,4-cyclohexylene group or a 1,4-phenylene group. Preferably, it is a 1, 4- phenylene group. A and B may be substituted, and as a substituent at that time, although a methyl group, an ethyl group, a methoxy group, etc. are mentioned as a preferable example, It is more preferable that it is substituted by the methyl group or is unsubstituted.

R ¹³ and R ¹⁴ are each independently a hydrogen atom or an acyl group having 1 to 10 carbon atoms, preferably a hydrogen atom, an acetyl group, propionyl group, butyryl group, or benzoyl group, and most preferably a hydrogen atom or It is an acetyl group. These R <^13> , R <^14> may be same or different, respectively.

Among the compounds represented by the above formula (I), glucose compounds represented by the following formula (II) are preferable.

&Lt; RTI ID = 0.0 &

(R ^15, of formula R ¹⁶ are, each independently, a carbon atom alkyl group of 1 to 6, or a carbon atom represents a 2-5 alkenyl group. These groups present one CH ₂ group or not adjacent to the two or more CH ₂ groups may be substituted with O ² is L, * -OCO-, -OCH ₂ -.. represents a * (* phenylene group bonded at side) R ^17, R ¹⁸ are, each independently, A hydrogen atom or an acyl group having 1 to 10 carbon atoms, each of R ¹⁹ and R ²⁰ independently represents a hydrogen atom, a methyl group, or a methoxy group);

Although the specific example of a compound represented by general formula (I) or (II) below is shown, this invention is not limited at all by the following specific examples. In addition, in this application, Ac represents an acetyl group.

The compound represented by general formula (I) which concerns on this invention can be synthesize | combined from (D) -glucose according to the following scheme. For example, J. Am. Chem. Soc., 2000, 124 (33), pp9756-9767 describe a method for synthesizing Intermediate B from (D) -glucose through acetal exchange, acylation, and selective deacylation of the first-order hydroxyl group. Arbitrary esterification reaction can be used as a method of guide | inducing to the glucose compound A from the following intermediate B, For example, the method of using the corresponding acid halide or a condensing agent, etc. are mentioned. As a method of obtaining glucose compound B, Carbohyd. Res. 1985, 135, 203., or Angew. Chem., Int. Ed. Engl. The method described in 1986, 25, 212., followed by the induction to intermediate C, followed by glycosylation with a corresponding alcohol. However, the synthesis | combining method of the compound which concerns on this invention is not limited to this example.

It is preferable that content of the compound represented by general formula (I) or (II) in the cellulose composition which concerns on this invention is 0.1-15 mass% with respect to a cellulose compound, More preferably, it is 0.5-10 mass%, Preferably it is 1-5 mass%.

The compound represented by the above-mentioned formula (I) or (II) can be used as a retardation increasing agent (controlling agent) for an optical film, and in particular, a retardation increasing agent for obtaining a film excellent in retardation expression property by stretching. It can be suitably used as.

<Carboxylic acid sugar ester>

It is preferable to add carboxylic acid sugar ester to the optical compensation film or transparent protective film which concern on this invention as needed.

Here, "carboxylic acid sugar ester" refers to a compound having an ester bond derived from a hydroxy group (also referred to as an "OH group") of a saccharide and a carboxy group of a carboxylic acid. However, in this application, a cellulose ester shall not be contained in the said carboxylic acid sugar ester.

As the carboxylic acid sugar ester, for example, an ester compound in which at least one of the pyranose structure or the furanose structure has at least one or more than 12 and esterified with a portion of the hydroxyl group of the structure can be preferably used. . It is preferable that the ratio of esterification is 70% or more.

In this invention, the compound represented by following General formula (1) can be used suitably as carboxylic acid sugar ester.

In the present invention, the degree of substitution of the compound represented by the formula (1) represents the number substituted by substituents other than hydrogen in the eight hydroxyl groups (hydroxyl groups) included in the formula (1), that is, R of the formula (1) ₁ through R _8, represents the number of groups containing other than hydrogen. Therefore, when all R <_1> -R <_8> is substituted by substituents other than hydrogen, substitution degree becomes 8.0 which is the maximum value, and when all R <_1> -R <_8> is hydrogen atoms, it becomes 0.0.

In this invention, it is preferable that substitution degree of the compound represented by General formula (1) is 2.8-6.0 from a viewpoint of retardation, transmittance | permeability, volatility, mechanical strength, etc. Moreover, 2.8-5.2 are more preferable.

As a substitution degree of the compound represented by General formula (1), it is suitable to use average substitution degree, and the average substitution degree can be measured from the area ratio of the chart which shows substitution degree distribution by high performance liquid chromatography by the following method. have.

Since cellulose ester of ultra-low substitution degree has many residual hydroxyl groups (hydroxyl groups), it is a point which is more water-resistant than the existing cellulose ester with high substitution degree. In order to improve it, a plasticizer may be added, but it will volatilize if compatibility is not met. In view of this point, the effect of the present invention can be further increased by adding a carboxylic acid sugar ester having a similar structure to that of the cellulose ester and having a low degree of substitution.

In addition, since the cellulose ester of ultra-low substitution degree is easy to be influenced by moisture, shrinkage at the time of durability when using a polarizing plate becomes a problem. Therefore, the effect of shrinkage in the polarizing plate is made by making the substitution degree of the carboxylic acid sugar ester smaller, leaving more hydroxy groups (hydroxyl groups), and softening the hydrogen bonds of the low-substituted cellulose ester and the carboxylic acid sugar ester very well. Can be made small.

In the general formula (1), R ₁ to R ₈ represent a hydrogen atom, a substituted or unsubstituted alkylcarbonyl group, or a substituted or unsubstituted arylcarbonyl group, that is, an acyl group, and R ₁ to R ₈ may be the same or different. (Hereinafter, R ₁ to R ₈ other than a hydrogen atom are also referred to as an acyl group).

As an example of the sugar of the synthetic raw material of the carboxylic acid sugar ester which concerns on this invention, although the following are mentioned, for example, this invention is not limited to these.

Glucose, galactose, mannose, fructose, xylose, or arabinose, lactose, sucrose, nystose, 1F-fructosyl nystose, stakiose, maltitol, lactitol, lactulose, cellobiose, Maltose, cellotriose, maltotriose, raffinose or kestoose.

In addition, gentiobiose, gentiootriose, gentiotetraose, xylotriose, galactosyl sucrose and the like may be mentioned.

Especially, sucrose is preferable from a viewpoint of compatibility and volatility.

As a monocarboxylic acid used at the time of the synthesis | combination of the carboxylic acid sugar ester which concerns on this invention, a well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, etc. can be used. The carboxylic acid used may be one kind or a mixture of two or more kinds.

Examples of preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelagonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylenic acid , Lauric acid, tridecyl acid, myristic acid, pentadecyl acid, palmitic acid, heptadecyl acid, stearic acid, nonadecanoic acid, arachnic acid, behenic acid, lignoseric acid, sertoic acid, heptaconic acid And saturated fatty acids such as montanic acid, melisic acid and lacseric acid, and unsaturated fatty acids such as undecylenic acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, arachidonic acid and octenic acid.

Examples of preferred alicyclic monocarboxylic acids include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, and derivatives thereof.

As an example of a preferable aromatic monocarboxylic acid, the aromatic monocarboxylic acid, cinnamic acid, benzyl acid, biphenylcarboxylic acid, naphthalenecar which introduce | transduced 1-5 alkyl groups or an alkoxy group into the benzene ring of benzoic acid, such as benzoic acid and toluic acid, is mentioned. Aromatic monocarboxylic acids which have two or more benzene rings, such as an acid and tetralin carboxylic acid, or derivatives thereof are mentioned, Especially benzoic acid is preferable.

A part of the specific example of the compound represented by General formula (1) which concerns on this invention is shown below, R in the following table represents either of the acyl groups represented by R <_1> -R <_8> in General formula (1). It shall be present.

The carboxylic acid sugar ester according to the present invention can be produced by reacting an acylating agent (an anhydride such as an acid halide of acetyl chloride, acetic anhydride, also referred to as an esterifying agent) with a sugar ester, and an esterification rate The distribution of is achieved by adjusting the amount of the acylating agent, the addition timing, and the esterification time, but by mixing a carboxylic acid sugar ester having a different esterification rate or a compound having a different esterification rate isolated from pure water, Carboxylic acid sugar esters can be prepared.

[Mat]

It is also preferable to add microparticles | fine-particles to an optical compensation film and a transparent protective film in order to prevent a flaw or deterioration of conveyability when the produced film is handled.

As fine particles, examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate Etc. can be mentioned. It is preferable that the fine particles include silicon because the turbidity is lowered, and silicon dioxide is particularly preferable.

The average particle diameter of the primary particles of the fine particles is preferably from 5 to 400 nm, more preferably from 10 to 300 nm. These may be contained mainly as a secondary aggregate with a particle diameter of 0.05-0.3 micrometer, It is also preferable that it is contained as a primary particle, without aggregating, if it is a particle | grain of an average particle diameter of 80-400 nm. It is preferable that it is 0.01-1 mass%, and, as for content of these microparticles | fine-particles in a film, 0.05-0.5 mass% is especially preferable. In the case of the optical compensation film of the multilayer constitution by a covalent smoke method, it is preferable to contain this addition amount microparticles on the surface.

The fine particles of silicon dioxide are commercially available under the trade names of, for example, Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, and TT600 (above Nippon Aerosil Co., Ltd.). .

The fine particles of zirconium oxide are commercially available under the trade names of Aerosil R976 and R811 (above Nippon Aerosil Co., Ltd.), for example, and can be used.

As an example of resin, a silicone resin, a fluororesin, and an acrylic resin are mentioned. A silicone resin is preferable, and it is preferable to have a three-dimensional network structure especially, for example, tos perl 103, tos perl 105, tos perl 108, tos perl 120, tos perl 145, tos perl 3120 and tos perl 240 (above Toshiba). It is marketed under the brand name of Silicone Co., Ltd., and can be used.

Among these, Aerosil 200V and Aerosil R972V are especially preferably used because the effect of lowering the coefficient of friction is great while keeping the haze of the optical compensation film low. In the optical compensation film which concerns on this invention, it is preferable that the dynamic friction coefficient of at least one surface is 0.2-1.0.

In addition, a mat agent may be disperse | distributed uniformly to the whole film and may be localized only to a surface layer.

(Method for producing optical compensation film and transparent protective film)

As a method for producing the optical compensation film and the transparent protective film according to the present invention, conventional production methods such as inflation method, T-die method, calender method, cutting method, casting method, emulsion method and hot press method can be used. The solution casting method by the casting method and the melt casting method are preferable from the viewpoints of suppression of coloring, suppression of foreign matter defects, suppression of optical defects such as die lines, and the like.

Hereinafter, the manufacturing method in the case of manufacturing the optical compensation film which concerns on this invention is demonstrated in detail. In addition, the transparent protective film which concerns on this invention can be manufactured by a conventionally well-known general method, For example, it can manufacture by the method according to the manufacturing method of the following optical compensation film.

<The manufacturing method of the optical compensation film by the solution casting method>

<< organic solvent >>

When manufacturing the optical compensation film which concerns on this invention by the solution casting | flow_spreading method, the organic solvent useful for forming dope can be used as long as it melt | dissolves thermoplastic resins, such as a cellulose ester resin.

For example, as the chlorine organic solvent, methylene chloride, and the non-chlorine organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone Ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3 , 3,3-hexafluoro-2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro -1-propanol, nitroethane, ethyl lactate, lactic acid, diacetone alcohol, etc. are mentioned, Methylene chloride, methyl acetate, ethyl acetate, acetone, ethyl lactate etc. can be used preferably.

In addition to the said organic solvent, dope may contain 1-40 mass% linear or branched aliphatic alcohol of 1-4 carbon atoms. When the proportion of alcohol in the dope increases, the web gels, and peeling from the metal support becomes easy, and when the proportion of alcohol is small, there is also a role of promoting dissolution of the thermoplastic resin in the non-chlorine organic solvent system.

In particular, it is preferable that the thermoplastic resin is a dope composition which melt | dissolved at least 10-45 mass% in total in the solvent containing methylene chloride and a C1-C4 linear or branched aliphatic alcohol.

Examples of the linear or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol and tert-butanol. Among these, ethanol is preferable at the point of stability of dope, comparatively low boiling point, and good dryness.

Hereinafter, the preferable film forming method of the optical compensation film (henceforth simply called "film") concerning this invention is demonstrated.

1) Dissolution Process

It is a process of forming a dope by melt | dissolving a thermoplastic resin and other additives in stirring kiln in the organic solvent which mainly uses a good solvent for a thermoplastic resin, stirring.

For dissolving the thermoplastic resin, a method performed at ordinary pressure, a method performed below the boiling point of the main solvent, a method performed by pressing above the boiling point of the main solvent, Japanese Patent Laid-Open No. 9-95544, Japanese Patent Laid-Open No. 9-95557 Although various dissolution methods, such as the method of performing by the cooling dissolution method as described in Unexamined-Japanese-Patent No. 9-95538, the method of performing at high pressure as described in Unexamined-Japanese-Patent No. 11-21379, can be used, Especially a main solvent The method of pressing and performing above the boiling point of is preferable.

The semi-finished material is a finely pulverized film, which cuts off both side portions of the film, which occurs when the film is formed, and is an out-of-specification film fabric due to scratches, etc., which is also reused.

2) Flexible process

The dope is fed to a press die via a feed pump (e.g., a pressurized metering gear pump), and is in a flexible position on a metal support such as an endless metal belt, for example, a stainless steel belt, or a rotating metal drum, which is fed indefinitely. It is a process of casting dope from a pressurized die slit.

The pressurization die which can adjust the slit shape of the metal member part of die | dye, and is easy to make film thickness uniform is preferable. There exist a coating hanger die, a T die, etc. in pressurization die | dye, and all are used preferably. The surface of the metal support is mirror-finished. In order to raise a film forming speed | rate, you may provide 2 or more press dies on a metal support body, and may divide | stack and dope amount. Or it is also preferable to obtain the film of a laminated structure by the covalent smoke method which simultaneously casts a plurality of dope.

3) Solvent evaporation process

It is a process of evaporating a solvent by heating a web (dope formed on the flexible support and called dope film | membrane a web) on a casting support.

In order to evaporate the solvent, there is a method of blowing air from the web side, and / or a method of heat transfer from the back side of the support by liquid, a method of heat transfer from front and back by radiant heat, and the like. Do. Moreover, the method of combining them is also used preferably. It is preferable to dry the web on the support body after casting | flow_spread on a support body in 40-100 degreeC atmosphere. In order to maintain in 40-100 degreeC atmosphere, it is preferable to adjust the warm air of this temperature to a web upper surface, or to heat by infrared rays or other means.

In view of surface quality, moisture permeability, and peelability, it is preferable to peel the web from the support within 30 to 120 seconds.

4) Peeling process

It is a process of peeling the web in which the solvent evaporated on the metal support body at a peeling position. The peeled web is sent to the next process.

The temperature at the peeling position on the metal support is preferably 10 to 40 ° C, more preferably 11 to 30 ° C.

In addition, although the amount of residual solvent at the time of peeling of a web on a metal support at the time of peeling is preferable to peel in 50-120 mass% in accordance with the strength of dry conditions, the length of a metal support, etc., When peeling at many points of time, if the web is too soft, the planarity is impaired at the time of peeling, and the amount of residual solvent at the time of peeling is determined by balancing the economical speed and quality, because it is easy to cause slack and vertical stripes due to the peeling tension.

The residual solvent amount of the web is defined by the following formula.

Residual solvent amount (%) = (mass before heat treatment of web-mass after heat treatment of web) / (mass after heat treatment of web) × 100

In addition, the heat processing at the time of measuring the amount of residual solvent shows performing heat processing for 1 hour at 115 degreeC.

Although the peeling tension at the time of peeling a metal support body and a film is 196-245 N / m normally, when wrinkles are easy to produce at the time of peeling, it is preferable to peel by the tension of 190 N / m or less, and also it can peel It is preferable to peel at the lowest tension to 166.6 N / m, and then to the lowest tension to 137.2 N / m, particularly preferably to peel at the lowest tension to 100 N / m.

In this invention, it is preferable to make temperature in the peeling position on the said metal support body into -50-40 degreeC, 10-40 degreeC is still more preferable, and it is most preferable to set it as 15-30 degreeC.

5) Drying and drawing process

After peeling, a web is dried using the drying apparatus which alternately passes a web through the roll arrange | positioned in multiple drying apparatuses, and / or the tenter stretching apparatus which clips and conveys both ends of a web with a clip.

The drying means generally blows hot air on both sides of the web, and there is also a means of heating microwaves instead of the wind. Too rapid drying tends to impair the planarity of the finished film. It is good to perform drying by high temperature from about 8 mass% or less of residual solvent. Through and drying are performed in general at 40-250 degreeC. It is especially preferable to dry at 40-160 degreeC.

When using a tenter stretching apparatus, it is preferable to use the apparatus which can independently control the grip length (distance from grip start to grip end) of a film by left and right holding means of a tenter independently from side to side. It is also desirable to make compartments with intentionally different temperatures in order to improve planarity in the tenter process.

It is also preferable to provide a neutral zone so that each compartment does not cause interference between different temperature compartments.

Moreover, extending | stretching operation may be divided | segmented into multistep, and it is also preferable to carry out biaxial stretching in the casting | flow_spread direction and the width direction. In addition, when biaxial stretching is performed, simultaneous biaxial stretching may be performed and you may carry out in steps.

In this case, with stage, it is also possible, for example, to perform extending | stretching different from each other in the extending | stretching direction sequentially, dividing extending | stretching of the same direction into multiple stages, and adding extending | stretching of a different direction to either of them can also be carried out. . That is, the following extending steps are also possible, for example.

Stretching in the flexible direction-Stretching in the width direction-Stretching in the flexible direction-Stretching in the flexible direction

Stretch in the width direction-Stretch in the width direction-Stretch in the flex direction-Stretch in the flex direction

In addition, simultaneous biaxial stretching also includes extending | stretching in one direction and reducing the tension and shrinking the other one. The preferable draw ratio of simultaneous biaxial stretching can be taken in the range of * 1.01 times-* 1.5 times in the width direction and the longitudinal direction.

It is preferable that the amount of residual solvent of a web in the case of tenter is 20-100 mass% at the time of tenter start, and it is preferable to dry, putting a tenter until the amount of residual solvent of a web becomes 10 mass% or less, More preferably, it is 5 mass% or less.

30-160 degreeC is preferable, as for the drying temperature in the case of tenter, 50-150 degreeC is more preferable, and 70-140 degreeC is the most preferable.

In a tenter process, it is preferable from the viewpoint of improving the uniformity of a film that there is little temperature distribution of the width direction of an atmosphere, and, as for the temperature distribution of the width direction in a tenter process, within ± 5 degreeC is preferable, and within ± 2 degreeC More preferably, it is most preferable within +/- 1 degreeC.

6) winding process

After the amount of residual solvent in a web becomes 2 mass% or less, it is a process of winding up by a winding machine as a film, and the film with favorable dimensional stability can be obtained by making the amount of residual solvent 0.4 mass% or less. It is preferable to wind up at 0.00-0.10 mass% especially.

As a winding method, what is generally used may be used, and there exist a static torque method, the positive tension method, the taper tension method, the program tension control method with constant internal stress, etc., and may just cover them.

It is preferable that it is a long film, the film which concerns on this invention shows the thing of about 100m-5000m specifically, and is a thing of the form provided in roll shape normally. Moreover, it is preferable that it is 1.3-4 m, and, as for the width of a film, it is more preferable that it is 1.4-2 m.

Although there is no restriction | limiting in particular in the film thickness of the film which concerns on this invention, It is preferable that it is 20-200 micrometers.

<The manufacturing method of the optical compensation film by the melt casting film forming method>

The method in the case of manufacturing thermoplastic resin film base materials, such as a cellulose ester resin and an acrylic resin which concerns on this invention as an optical compensation film, by the melt casting film forming method is demonstrated.

<Melt pellet manufacturing process>

It is preferable to knead | mix and pelletize the composition which comprises the thermoplastic resin film used for melt extrusion normally previously.

Pelletization may be a known method, for example, by supplying an additive to a extruder by a feeder according to the dry thermoplastic resin and the purpose, kneading using a single or twin-screw extruder, extruded into a strand shape from the die, water-cooled or It can cool by air-cooling and can cut.

Drying the raw material before extrusion is important in preventing decomposition of the raw material. Since cellulose ester is especially easy to absorb moisture, it is preferable to dry at 70-140 degreeC or more with a dehumidification hot air dryer or a vacuum dryer for 3 hours or more, and to make moisture content 200 ppm or less and 100 ppm or less.

The additives may be mixed before being fed to the extruder or may be fed to individual feeders, respectively. In order to mix uniformly a small amount of additives, such as antioxidant, it is preferable to mix before supplying to an extruder.

The mixture of antioxidants may be mixed with each other, and if necessary, the antioxidant may be dissolved in a solvent, impregnated with a thermoplastic resin and mixed, or sprayed and mixed.

A vacuum Nauta mixer or the like is preferable because drying and mixing can be performed at the same time. In addition, when in contact with the outlet, such as air from the feeder portion and the die, it is preferable that the atmosphere up and down, such as dehumidified air and the dehumidifying a N ₂ gas.

It is preferable that the extruder is capable of pelletizing so as to suppress the shearing force and prevent the resin from deteriorating (reducing molecular weight, coloring, gel formation, etc.) and processing at a low temperature as possible. For example, in the case of a twin screw extruder, it is preferable to rotate in the same direction using a screw of a deep groove type. In view of the uniformity of the kneading, the engagement type is preferred.

Film formation is carried out using the pellets obtained as described above. It is also possible to supply powder of a raw material to an extruder with a feeder as it is, without pelletizing, and to film-form as it is.

<Step of extruding molten mixture from die to cooling roll>

First, the produced pellets are extruded using a single screw or twin screw extruder, and the melt temperature (Tm) at the time of extruding is set to about 200 to 300 ° C., filtered through a leaf disk type filter or the like to remove foreign substances, and then T The film is coextruded from the die into a film, solidified on a cooling roll, and flexible while being pressed with an elastic touch roll.

When introducing into the extruder from the feed hopper, it is preferable to prevent oxidative decomposition or the like under vacuum or reduced pressure or inert gas atmosphere. In addition, Tm is the temperature of the die | dye exit part of an extruder.

If foreign matter such as a scratch or a plasticizer condensation adheres to the die, a stripe defect may occur. Although such a defect is also called a die line, in order to reduce the defect of the surface, such as a die line, it is preferable to set it as the structure in which the retention part of resin is as small as possible in the piping from an extruder to a die. It is preferable to use the one which does not have scratches or the like inside the die or the lip as much as possible.

It is preferable that the inner surface which contacts with molten resin, such as an extruder and die | dye, is made the surface process which hardly adheres to molten resin, by making surface roughness small or using the material with low surface energy. Specifically, what polished so that hard chromium plating or the ceramic thermal sprayed thing may be 0.2S or less of surface roughness is mentioned.

In the present invention, the cooling roll is not particularly limited, but is a roll having a structure in which a thermally controllable thermal medium or a cooling medium flows through a highly rigid metal roll, and the size is not limited, but is sufficient to cool the melt-extruded film. What is necessary is just size, and the diameter of a cooling roll is about 100 mm-about 1 m normally.

Examples of the surface material of the cooling roll include carbon steel, stainless steel, aluminum, titanium, and the like. Moreover, in order to improve the hardness of a surface, or to improve peelability with resin, it is preferable to perform surface treatment of hard chromium plating, nickel plating, amorphous chromium plating, etc., ceramic spraying, etc.

It is preferable to make surface roughness of a cooling roll surface into 0.1 micrometer or less by arithmetic mean roughness Ra, and also to be 0.05 micrometer or less. The smoother the roll surface, the smoother the surface of the resulting film can be. Of course, it is preferable that the surface processed is further polished and made into the surface roughness mentioned above.

In this invention, as an elastic touch roll, Unexamined-Japanese-Patent No. 03-124425, Unexamined-Japanese-Patent No. 08-224772, Unexamined-Japanese-Patent No. 07-100960, Unexamined-Japanese-Patent No. 10-272676, WO97 / 028950, Japan Use of a silicone rubber roll coated with a thin film metal sleeve described in Japanese Patent Laid-Open No. 11-235747, Japanese Patent Laid-Open No. 2002-36332, Japanese Patent Laid-Open No. 2005-172940 or Japanese Patent Laid-Open No. 2005-280217 Can be.

When peeling a film from a cooling roll, it is preferable to control tension and prevent deformation of a film.

<Stretching Step>

In the present invention, the film obtained as described above may be stretched 1.01 to 3.0 times in at least one direction after passing through a step of contacting the cooling roll.

Preferably, it is preferably stretched 1.1 to 2.0 times in both vertical (film conveyance directions) and horizontal (width directions) directions.

As a method of extending | stretching, a well-known roll stretching machine, a tenter, etc. can be used preferably. In particular, when the optical compensation film also serves as a polarizer protective film, lamination with the polarizing film can be made in roll form by making the stretching direction the width direction.

By extending | stretching in the width direction, the slow axis of an optical compensation film becomes a width direction.

Usually, draw ratio is 1.1-3.0 times, Preferably it is 1.2-2 times, and extending | stretching temperature is Tg-Tg + 50 degreeC of resin which comprises a film normally, Preferably it is the temperature range of Tg-Tg + 50 degreeC. Is done in.

It is preferable to perform extending | stretching under uniform temperature distribution controlled in the longitudinal direction or the width direction. It is preferably within ± 2 ° C, more preferably within ± 1 ° C, particularly preferably within ± 0.5 ° C.

When using the film-form resin film produced by the said method as an optical compensation film, you may shrink | contract a film in the longitudinal direction or the width direction for the purpose of adjusting the phase difference (retardation) of the said optical compensation film and reducing the rate of dimensional change. .

In order to shrink | contract in the longitudinal direction, for example, there is a method of shrinking the film by temporarily clipping out the width stretching to relax in the longitudinal direction or by gradually narrowing the interval between adjacent clips of the transverse stretching machine.

Uniformity in the slow axis direction is also important, and it is preferable that the angle is in the range of -5 to + 5 ° with respect to the film width direction, and also preferably in the range of -1 to + 1 °, and particularly in the range of -0.5 to + 0.5 °. It is preferable to exist in a range, and it is especially preferable to exist in the range of -0.1 to +0.1 degrees. Such deviation can be achieved by optimizing the stretching conditions.

It is preferable that it is a long film, and the optical compensation film which concerns on this invention shows the thing of about 100m-10000m specifically, and is a thing of the form provided in roll shape normally. Moreover, it is preferable that it is 1.3-4 m, and, as for the width of a film, it is more preferable that it is 1.4-2.5 m.

There is no restriction | limiting in particular in the film thickness of the optical compensation film which concerns on this invention, It is preferable to change according to the objective. For example, when using for a polarizer protective film, it is preferable that it is 20-200 micrometers.

(Liquid crystal display device)

By using the polarizing plate of this invention for a liquid crystal display device, the liquid crystal display device which concerns on this invention excellent in various visibility can be manufactured.

The polarizing plate of this invention can be used for the liquid crystal display of various drive systems, such as STN, TN, OCB, HAN, VA (MVA, PVA), IPS, OCB. Preferably, they are In-Plane-Switching (IPS) and Vertical Alignment (VA) type liquid crystal display devices.

Especially in this invention, it is a liquid crystal display device which has a backlight, a liquid crystal cell, and a polarizing plate one by one on the viewing side and a backlight side of the said liquid crystal cell, The polarizing plate obtained by cutting the elongate polarizing plate of this invention is further equipped, The liquid crystal display device which satisfy | fills the following requirements (a)-(c) is preferable from a viewpoint of brightness unevenness improvement.

(a) As the polarizing plate (hereinafter referred to as "polarizing plate 1") on the backlight side of the liquid crystal cell, the optical compensation film (hereinafter referred to as "optical compensation film 1") of the polarizing plate obtained by cutting the elongate polarizing plate according to claim 1 It is arrange | positioned so that it may become the said liquid crystal cell side.

(b) The polarizing plate (hereinafter referred to as "polarizing plate 2") on the visual side of the liquid crystal cell is a polarizing plate in which a transparent protective film, a polarizer and an optical compensation film (hereinafter referred to as "optical compensation film 2") are laminated in this order. It is arrange | positioned so that the said optical compensation film 2 may be said liquid crystal cell side.

(c) The polarizing plates 1 and 2 are arranged so that the absorption axes are orthogonal to each other.

Moreover, the said liquid crystal cell is a vertically-aligned liquid crystal cell, the said optical compensation film 2 contains the cellulose ester which acyl-group substitution degree exists in the range of 2.0-2.6, Moreover, said Formula (2)-Formula (5) It is preferable that the relationship represented by) is satisfied.

Moreover, the liquid crystal display device of the form in which a reflection type brightness improving film is provided between the said backlight and the polarizing plate 1, and is arrange | positioned so that the transmission axis of the said reflection type brightness improving film and the absorption axis of the polarizer of the said polarizing plate 2 orthogonally crosses. It is preferable from the viewpoint of maintaining black display performance.

[Vertical Alignment Type Liquid Crystal Cell]

It is preferable that the liquid crystal display device of this invention has a vertically-aligned liquid crystal cell. As a liquid crystal cell which concerns on this invention, various conventionally well-known liquid crystal cells, for example, VA (MVA, PVA) type, VA-IPS, TBA type Etc. can be used. The dielectric anisotropy of the liquid crystal held by two transparent substrates may be positive or negative.

The present invention also applies to a COA method. As described in, for example, Japanese Patent Application Laid-Open No. 2011-28207, the COA method uses a color filter integrated drive substrate and a counter electrode (conductive layer) in which a color filter is directly formed on a drive side substrate of a liquid crystal cell. The counter substrate provided is disposed to face each other with a spacer interposed therebetween, and a liquid crystal material is enclosed in the gap portion. The color filter is formed on the reflective electrode, and the bonding margin can be widened at high precision to improve the yield and the aperture ratio. have.

In the present invention, the liquid crystal cell is, for example, negative in dielectric anisotropy between the upper and lower substrates, and a nematic liquid crystal material of Δn = 0.0815 and Δε = -4.5 or the like can be used.

Although it does not restrict | limit especially about the thickness d of a liquid crystal layer, When using the liquid crystal of the characteristic of the said range, it can set to about 3.5 micrometers, for example.

In addition, in a vertically-aligned (VA type) liquid crystal display device, although the addition of the chiral material generally used in the TN mode liquid crystal display device is used in order to reduce dynamic response characteristics, in order to reduce an orientation defect, It may be added.

In addition, in the case of a multi-domain structure, it is advantageous to adjust the orientation of liquid crystal molecules in the boundary region between each domain.

In addition, the "multi-domain structure" means the structure which divided | segmented one pixel of the liquid crystal display device into the several area | region. For example, in the vertically-aligned (VA type) liquid crystal display device, since the liquid crystal molecules are inclined at the time of white display, the magnitude of the birefringence of the liquid crystal molecules when observed in the inclination direction is different in the inclination direction and the reverse direction thereof. A difference occurs in luminance and color tone, but a multi-domain structure is preferable because the viewing angle characteristic of luminance and color tone is improved.

Specifically, by constituting and averaging each pixel into two or more regions having different initial alignment states of the liquid crystal molecules, it is possible to reduce the deviation of luminance and color tone depending on the viewing angle. The same effect can be obtained even when each pixel is constituted by two or more different regions in which the alignment direction of the liquid crystal molecules continuously changes in the voltage application state.

In order to obtain a uniform viewing angle in all directions, the number of divisions may be increased, but by setting it as 4 divisions or more, a substantially uniform viewing angle is obtained.

The present invention can obtain a liquid crystal display device excellent in luminance unevenness at the time of black display, especially when the screen is applied to a vertically oriented liquid crystal display device of a large screen of 30 type or more.

When bonding a polarizing plate to a cell, you may carry out by the roll-to-panel system which joins in a roll-shaped state, without cutting out the polarizing plate of a piece from an elongate polarizing plate beforehand.

Example

Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these.

&Lt; Example 1 >

(Production of polarizer A1)

A polyvinyl alcohol film having a thickness of 75 μm was swollen with water at 35 ° C., which was immersed in an aqueous solution containing 0.075 g of iodine, 5 g of potassium iodide, and 100 g of water for 60 seconds, followed by 3 g of potassium iodide, 7.5 g of boric acid, After being immersed in 45 degreeC aqueous solution containing 100 g of water, transverse stretching by a tenter was performed at 55 degreeC by draw ratio 4.5 times. This was washed with water, dried, and wound to obtain an elongated polarizer A1 having a winding length of 1000 m.

(Production of polarizer A2)

The polarizer A2 was produced by the method which has the following process.

(1) Swelling process and stretching process

A polyvinyl alcohol (PVA) film (film width: 300 mm) having a thickness of 75 µm having a polymerization degree of 2400 and a saponification degree of 99.9% was prepared. Single side | surface of the said PVA film was swelled by immersing in 30 degreeC warm water (swelling bath) for 60 second, and tenter extending | stretching (horizontal stretching) was performed in the width direction so that it might become 2 times length with respect to the width of the film before swelling.

(2) dyeing process and stretching process

The PVA film was taken out of the swelling bath, immersed for 60 seconds in an aqueous solution (dyeing bath) at a concentration of 3.2% by mass of 30% by mass containing iodine and potassium iodide in a mass ratio of 1: 7, and the PVA film before the swelling step. Tenter extending | stretching (horizontal stretching) was performed in the width direction so that it might become 3.5 times the length with respect to the width.

(3) crosslinking process and stretching process

After taking out the said PVA film from the said dyeing bath and immersing in 30 degreeC aqueous solution (crosslinking bath) containing 3 mass% boric acid and 3 mass% potassium iodide for 20 second, about the width of the PVA film before the said swelling process, The tenter stretching (horizontal stretching) was performed in the width direction so as to have a length of 3.6 times.

(4) stretching process

The PVA film was taken out of the crosslinking bath, immersed in an aqueous solution at 60 ° C. (extension bath) containing 4% by mass of boric acid and 5% by mass of potassium iodide for 60 seconds, and 5.9 with respect to the width of the PVA film before the swelling step. Tenter extending | stretching (horizontal stretching) was performed in the width direction so that it might become length of a ship.

(5) Adjustment (iodine ion impregnation treatment), drying process

The said PVA film was taken out from the said stretching bath, and it was immersed for 20 second in 30 degreeC aqueous solution (adjustment bath) containing 3 mass% potassium iodide. Then, this PVA film was dried at 60 degreeC for 4 minutes, and the polarizer A2 of this Example was obtained.

The width axis angle of the absorption axis of the obtained polarizer was -3 ° at the right end of the fabric and + 3 ° at the left edge when the fabric center was set at 0 ° (TD direction). It was.

(Production of polarizer A3)

A polyvinyl alcohol film having a thickness of 75 μm was swollen with water at 35 ° C., which was immersed in an aqueous solution containing 0.075 g of iodine, 5 g of potassium iodide, and 100 g of water for 60 seconds, followed by 3 g of potassium iodide, 7.5 g of boric acid, and water. It immersed in 45 degreeC aqueous solution containing 100g, and uniaxially stretched (temperature 55 degreeC, draw ratio 5 times). This was washed with water and dried to obtain a polarizer A3.

(Production of polarizer A4)

Polarizer A4 was produced in the same manner as in the production of polarizer A1 except that the draw ratio was tripled.

(Evaluation of Nz coefficient of polarizer)

Using KOBRA-WX100 / IR (manufactured by Oji Keisukuki Co., Ltd.), n _x , n _y , n _z were obtained at a wavelength of 1000 nm under an environment of a temperature of 23 ° C. and a humidity of 55% RH, and Nz Was calculated. The average refractive index was 1.60. Table 1 shows the results.

(Production of optical compensation film C1)

<Fine Particle Dispersion 1>

11 parts by mass of fine particles (Aerosil R812 Nippon Aerosil Co., Ltd. product)

Ethanol 89 parts by mass

The mixture was stirred with a dissolver for 50 minutes and then dispersed with Manton-Gaulin.

&Lt; Fine Particle Addition Solution 1 >

The fine particle dispersion 1 was slowly added while sufficiently stirring in a dissolution tank containing methylene chloride. In addition, dispersion was performed by grinding to make the particle diameter of the secondary particles become a predetermined size. This was filtered with Fine Mat NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle addition liquid 1.

99 parts by mass of methylene chloride

Fine particle dispersion 15 parts by mass

The main doping of the following composition was prepared. First, methylene chloride and ethanol were added to the pressure-melting tank. It injected | threw-in stirring the cellulose ester of acetyl group substitution degree 2.45 to the pressure dissolution tank containing a solvent. This was heated and dissolved completely with stirring. This was filtered using Azumi Rossi No. 244 manufactured by Azumi Rossi Co., Ltd. to prepare a main dope.

<Composition of main dope>

Methylene chloride 340 parts by mass

Ethanol 64 parts by mass

100 mass parts of cellulose esters (acetyl group substitution degree 2.45, Mn = 60000)

12 parts by mass of a sugar ester compound M

11 parts by mass of fine particle addition liquid

The above was put into the sealed main melting kiln, and it melt | dissolved stirring, and dope was manufactured.

<Synthesis of carboxylic acid sugar ester compound M>

Sucrose 34.2 g (0.1 mol), 135.6 g (0.6 mol) of benzoic anhydride, 284.8 g (3.6 mol) of pyridine were added to a four-necked colbene equipped with a stirring device, a reflux condenser, a thermometer, and a nitrogen gas introduction tube. The temperature was raised while bubbling nitrogen gas from the nitrogen gas introduction tube, and the esterification reaction was performed at 70 ° C for 5 hours.

Subsequently, the internal pressure of collven was reduced to 4 × 10 ² Pa or less, excess pyridine was distilled off at 60 ° C., the pressure in corbene was reduced to 1.3 × 10 Pa or less, and the temperature was raised to 120 ° C. to obtain an anhydrous benzoic acid Most were distilled off. Subsequently, 300 g of an aqueous solution of sodium carbonate of 0.5% by mass and 1 L of toluene was added, stirred at 50 캜 for 30 minutes, and then allowed to stand to separate the toluene layer. Finally, water was added to 100g at a separated toluene layer, and then for 30 minutes at room temperature, washed with water, and the separated toluene layer under reduced pressure (4 × 10 ² or less Pa), to remove the toluene distilled at 60 ℃, compound A The sugar ester compound M which was a mixture of -1, A-2, A-3, A-4, and A-5 was obtained.

As a result of analyzing the obtained mixture by high performance liquid chromatography mass spectrometry (HPLC-MS), 1.2 mass% of A-1, 13.2 mass% of A-2, 14.2 mass% of A-3, and 35.4 mass% of A-4 And A-5 were 40.0 mass%. Average substitution degree was 5.2.

On the stainless steel belt support, the solvent was evaporated until the amount of residual solvent in the cast film became 75%. Then, it peeled on the stainless steel belt support body by peeling tension 130N / m. The peeled optical compensation film was extended | stretched 35% in the width direction using the tenter, applying 170 degreeC heat. The residual solvent at the start of the stretching was 15%.

Subsequently, drying was completed while conveying the drying zone to a plurality of rolls. The drying temperature was 130 占 폚, and the conveying tension was 100 N / m. As described above, an optical compensation film C1 having a dry film thickness of 38 μm was obtained. The in-plane retardation value Ro of the optical compensation film C1 was 52 nm, and the thickness direction retardation value Rt was 125 nm.

(Production of optical compensation film C2)

<Silicon Dioxide Dispersion>

10 parts by mass of aerosil R812 (manufactured by Nippon Aerosil Co., Ltd.)

(Average diameter of primary particles: 7 nm)

90 parts by mass of ethanol

The resulting mixture was stirred with a dissolver for 30 minutes and dispersed with Manton-Gaulin. 88 parts by mass of methylene chloride was added to the silicon dioxide dispersion while stirring, and the mixture was stirred with a dissolver for 30 minutes to prepare a silicon dioxide dispersion diluted solution. Filtration was carried out with a fine particle dispersion dilution filter (Adventic Orient Co., Ltd .: polypropylene wind cartridge filter TCW-PPS-1N).

<Dope composition>

90 parts by mass of cellulose triacetate

(Cellulose triacetate synthesized from the linter side, acetyl group substitution degree 2.88, Mn = 140000)

10 parts by mass of an acrylic compound

4 parts by mass of silicon dioxide dispersion diluent

432 parts by mass of methylene chloride

38 parts by mass of ethanol

The above was put into an airtight container, it heated, it melt | dissolved, stirring, and filtered using Azumi Rossi No.24 by Azumi Rossi Co., Ltd., and dope was manufactured.

Subsequently, it casted uniformly on the stainless steel band support body using the belt casting apparatus. On the stainless steel band support, the solvent was evaporated until the amount of residual solvent became 100% and peeled off on the stainless steel band support. The solvent of the cellulose-ester film was evaporated at 35 degreeC, it slit to 1.65 m width, it width-retained by the tenter, and it dried at 160 degreeC drying temperature (also called heat processing temperature and extending | stretching temperature). The residual solvent amount at the start of drying was 20%. Then, after drying for 15 minutes, conveying the inside of a 120 degreeC drying apparatus with many rolls, a knurling process of width 15mm and a height of 5 micrometers is given to the both ends of a film, it winds up to a winding core, and optical compensation of a film thickness of 20 micrometers Film C2 was obtained. In-plane retardation value Ro of this optical compensation film C2 was 0 nm, and thickness direction retardation value Rt was 5 nm. The residual solvent amount of the optical compensation film C2 was 0.2%, and the winding number was 6000 m.

Synthesis of Acrylic Compound

In a glass flask with a stirrer, two dropping funnels, a gas introduction tube and a thermometer, 40 g of a monomer mixture liquid containing 80 MMA (methyl methacrylate) and 20 HEA (β-hydroxyethyl acrylate) mixed, 3.0 g of mercaptopropionic acid and 30 g of toluene were added, and the temperature was raised to 90 ° C. Thereafter, 60 g of the same monomer mixture liquid was added dropwise over 3 hours from one dropping funnel, and 0.6 g of azobisisobutyronitrile dissolved in 14 g of toluene was simultaneously dropped over 3 hours from the other funnel. . Thereafter, 0.6 g of azobisisobutyronitrile dissolved in 56 g of toluene was further added dropwise over 2 hours, and then the reaction was continued for 2 hours to obtain an acrylic compound.

<Measurement of molecular weight>

The weight average molecular weight was measured using high performance liquid chromatography.

Measurement conditions are as follows.

Solvent: methylene chloride

Column: Shodex K806, K805, K803G (three manufactured by Showa Denko Co., Ltd. were used)

Column temperature: 25 ° C

Sample concentration: 0.1 mass%

Detector: RI Model 504 (manufactured by GL Science)

Pump: L6000 (manufactured by Hitachi Seisakusho Co., Ltd.)

Flow rate: 1.0 ml / min

Calibration curve: Standard polystyrene STK standard A calibration curve with 13 samples of polystyrene (manufactured by Tosoh Corporation) Mw = 1000000 to 500 was used. 13 samples are used at almost equal intervals.

(Production of optical compensation films C3 and C5)

In the following chemical formula, R ¹ is a hydrogen atom, R ² and R ³ are methyl groups (meth) acrylic resins having a lactone ring structure {copolymerization monomer mass ratio = methyl methacrylate / 2- (hydroxymethyl) methyl acrylate = 8 / 2, lactone cyclization rate about 100%, content rate of lactone ring structure 19.4%, weight average molecular weight 133000, melt flow rate 6.5g / 10min (240 degreeC, 98N (10kgf), Tg 131 degreeC) 90 mass parts, and acrylo Pellets of a mixture of 10 parts by mass of a nitrile-styrene (AS) resin (Toyo AS AS20, manufactured by Toyo Styrene) (Tg 127 ° C) were fed to a twin screw extruder and melt-extruded into a sheet at about 280 ° C to form a film thickness 43 A (meth) acrylic resin sheet having a lactone ring structure of µm was obtained, The unstretched sheet was stretched 2.0 times in length and 2.4 times in width under a 160 ° C temperature condition to give a (meth) acrylic resin film C3 having a thickness of 15 µm. In-plane phase difference value Ro of this optical compensation film C3: 0 nm, and thickness direction retardation value Rt were 0 nm.

Corona discharge treatment (corona discharge electron irradiation amount: 77 W / m ² / min) was performed on one side of the (meth) acrylic resin film. 16.8 g of polyester urethane (made by Daiichi Kogyo Seiyaku, brand name: Super Flex 210, solid content: 33%), crosslinking agent (oxazoline-containing polymer, Nippon Shokubai manufactured, brand name: Epocross WS-700, solid content: 25%) 4.2 g, 1 mass% of ammonia water 2.0 g, colloidal silica (fuso Kagaku Kogyo Co., Ltd., Quattron PL-3, solid content: 20 mass%), 0.42 g, and pure water 76.6g were mixed, and the adhesion agent composition was obtained.

The obtained adhesive composition was apply | coated with the bar coater (# 6) so that the thickness after drying might be 350 nm to the corona discharge treatment surface of the (meth) acrylic resin film which performed the corona discharge treatment. Then, the (meth) acrylic resin film was put into a hot air dryer (140 degreeC), the adhesive agent composition was dried for about 5 minutes, the easily bonding layer (0.3-0.5 micrometer) was formed, and the optical compensation film C3 was obtained. .

Except having set the film thickness at the time of melt extrusion into 25 micrometers, the optical compensation film C5 with a film thickness of 8 micrometers was obtained similarly. In-plane retardation value Ro of this optical compensation film C5 was 0 nm, and thickness direction retardation value Rt was 0 nm.

(Production of optical compensation film C4)

A polymer film (Neonbon Xeon Co., Ltd. make, brand name "Zenooa", film thickness: 100 micrometers, film width: 700 mm) containing a norbornene-based resin was three times as wide as 1 axis at 143 ° C using a tenter stretching machine. Stretching was performed to obtain an optical compensation film C4 having a thickness of 35 μm. In-plane retardation value Ro of obtained optical compensation film C4 was 270 nm, and thickness direction retardation value Rt was 197 nm.

(Phase Difference Measurement)

After humidifying the produced optical compensation film at 23 degreeC 55% RH, phase difference was measured at the measurement wavelength of 590nm using Axoscan by Axometrcs. The average refractive index for Rt calculation measured the refractive index of three directions with the Abbe refractometer, and used the average value of them.

The measurement results are shown in Table 2.

(Transparent protective film)

Commercially available Konica Minolta Advanced Layer Co., Ltd. KC4UA-SW and KC6UA-SW were used as transparent protective films B1 and B2, respectively.

(Production of Polarizing Plates P1 and 2)

Alkaline saponification was performed using the transparent protective film B1 and the produced optical compensation film using 50 degreeC 2N KOH aqueous solution, and it washed with water and dried, and performed the polarizing plate process as follows.

The saponified film on both sides of the produced polarizer A1 was formed by sandwiching a polarizer into both films using a water pool, and a pressure of 20 to 30 N / cm ² and a conveying speed were bonded at about 10 m / min. The drying process was performed at 60 degreeC for about 2 minutes, and then at 60 degreeC for about 2 minutes, and the winding and the polarizing plate roll were produced. The adhesive layer was provided in the polyethylene terephthalate film which carried out the peeling process, the surface of the adhesion layer was affixed on the optical compensation film side of the obtained polarizing plate, and the adhesive polarizing plate roll was produced. Table 3 shows the correspondence between the film used as the transparent protective film and the optical compensation film and the polarizing plate.

(Production of Polarizing Plates P3 and P5)

Alkaline saponification process was performed using 50 degreeC 2N KOH aqueous solution, and the transparent protective film B1 was washed with water and dried.

(Production of Adhesive Composition)

20 parts by mass of methylolmelamine is pure water at a temperature of 30 ° C based on 100 parts by mass of acetoacetyl group-containing polyvinyl alcohol-based resin (average degree of polymerization: 1200, saponification degree: 98.5 mol%, acetoacetyl group modification: 5 mol%). It melt | dissolved in and obtained the aqueous solution of 0.5% of solid content concentration. The obtained aqueous solution was used under the temperature conditions of 30 degreeC as an adhesive composition.

(Production of polarizing plate)

30 minutes after manufacture of the said adhesive composition, the adhesive composition was apply | coated to the easily bonding layer side of the optical compensation film C3 or C5 so that the thickness after drying might be 50 nm. Similarly, the adhesive composition was apply | coated to the one side of the alkali saponification process completed transparent protective film B1 as mentioned above. Then, the transparent protective film B1 and the optical compensation film C3 or C5 are laminated | stacked using the laminator on both sides of the polarizer A1 via an adhesive composition, and it puts into a hot air dryer (70 degreeC), and it dries for 5 minutes, Polarizing plates P3 and P5 were obtained. Table 3 shows the correspondence between the film used as the transparent protective film and the optical compensation film and the polarizing plate.

(Production of Polarizing Plate P4)

The said polarizer A2, the said optical compensation film C4, and the transparent protective film B1 were bonded by the adhesive agent so that the polarizer A2 might be between the optical compensation film C4 and the transparent protective film B1. The adhesive agent is 20 mass parts of methylol melamine with respect to 100 mass parts of polyvinyl alcohol-type resins (average degree of polymerization: 1200, saponification degree: 98.5 mol%, acetacetylation degree: 5 mol%) which have an acetoacetyl group on 30 degreeC conditions. The aqueous solution which melt | dissolved in the pure water and manufactured at solid content concentration of 3.2 mass% was used. Using this adhesive agent, after bonding the said optical compensation film C4 and the said transparent protective film B1 with a roll on both surfaces of the said polarizer on the temperature conditions of 30 degreeC, it dried at 60 degreeC for 4 minutes, and produced the polarizing plate P4.

(Evaluation of reworkability)

The obtained polarizing plates P1 to P5 were punched out to a size of 100 × 100 mm and bonded to the glass base. In one place of four corners, the polarizing plate was slightly peeled from the glass base, and the peeled polarizing plate was gripped and peeled in the diagonal direction while pressing the glass base. The same operation was performed with 10 samples in total, and the evaluation was performed according to the following criteria.

(Circle): Peeling residue generate | occur | produces in 0-5 sheets

X: 6 or more peeling residues generate | occur | produce

Table 3 shows the results of the evaluation.

As apparent from the evaluation results shown in Table 3, it is understood that the reworkability is improved in the polarizing plate of the present invention.

<Example 2>

(Production of optical compensation film C6)

(Dope composition 1)

70 parts by mass of diamond BR85 (manufactured by Mitsubishi Rayon Co., Ltd.)

30 mass parts of cellulose esters (cellulose acetate propionate; average acyl group substitution degree 2.75, acetyl group substitution degree 0.19, propionyl group substitution degree 2.56, Mw = 200000)

300 parts by mass of methylene chloride

40 parts by mass of ethanol

It melt | dissolved fully, heating the said composition, and dope was produced.

(Film Formation)

The produced dope was uniformly cast on the stainless steel band support body at the temperature of 22 degreeC, and 2 m width using the belt casting apparatus. In the stainless steel band support, the solvent was evaporated until the amount of residual solvent became 100%, and it peeled from the stainless steel band support body on peeling tension 162 N / m.

The solvent was evaporated at 35 ° C., and the web of the peeled acrylic resin was slitted to a width of 1.6 m, and then dried at a drying temperature of 135 ° C. while stretching at a width of 1.1 times with a tenter. At this time, the amount of residual solvent when extending | stretching with a tenter was 10%.

After extending | stretching with a tenter, after relaxing at 130 degreeC for 5 minutes, drying was terminated, conveying the drying zone of 120 degreeC and 140 degreeC with many rolls, and it slitted to 1.5 m width, and width 10mm height 5 micrometers in both ends of a film. The knurling process was performed, it wound up to the inner diameter of 15.24cm core by the initial tension of 220N / m, and the last tension of 110N / m, and obtained the acrylic resin film.

The draw ratio in the MD direction calculated from the rotational speed of the stainless steel band support and the operating speed of the tenter is 1.1 times, the residual solvent amount of the finished film is 0.1%, the film thickness is 20 µm, the in-plane retardation value (Ro) is 0 nm, the thickness The direction retardation value Rt was 0 nm and the winding length was 4000 m.

(Formation of Adhesion Facing Layer)

On one side of the produced film, the coating liquid 1a having the following composition was applied so that the wet film thickness (wd) was 20 μm, and further dried at 100 ° C. for 5 minutes to form an easy-adhesive layer. C6 was produced.

<Production of Coating Liquid 1a>

0.8 mass part of cellulose diacetate (the Daicel Chemical Industries, Ltd. make, brand name: L-50)

Acetone 7 parts by mass

7 parts by mass of methyl ethyl ketone

6 parts by mass of methanol

(Production of Polarizing Plates P11 to 14)

Polarizing plate P11 was produced like P1 and P13 similarly to P3. However, about the optical compensation film C6, it bonded together so that the surface on which the adhesion facilitation process was performed may become a polyvinyl alcohol side. Table 4 shows the correspondence between the film used as the transparent protective film, the optical compensation film, and the polarizer, and the polarizing plate.

(Fabrication of liquid crystal display device)

The polarizing plate of Toshiba Corporation REGZA42ZS1 which is IPS mode was peeled off, the polarizing plate produced above was bonded to the panel by the combination shown in Table 5, the liquid crystal display devices (1-1 to 1-4) were produced, and the following evaluation was performed It was done.

(Stain evaluation)

A black display was displayed on the screen while the backlight was turned on, and luminance unevenness was evaluated by visual observation according to the following criteria.

◎: 0 to 2 of 10 stains can be confirmed

○: 3 to 5 of 10 stains can be confirmed

X: The stain | clear | clear_clear so that 6-10 of 10 stain | stain can be confirmed

The results of the evaluation are shown in Table 5.

As is apparent from the evaluation results shown in Table 5, it can be seen that the liquid crystal display device using the polarizing plate of the present invention is excellent enough to hardly confirm luminance unevenness.

<Example 3>

(Production of optical compensation film C11)

An optical compensation film C11 having a dry film thickness of 70 μm was obtained in the same manner as the film C1 except that the draw ratio was 40% and the film thickness was changed. In-plane retardation value Ro of this optical compensation film C11 was 70 nm, and thickness direction retardation value Rt was 240 nm.

(Production of optical compensation film C12)

(Production of particulate dispersion)

11 parts by mass of fine particles (aerosil R972V (made by Nippon Aerosil Co., Ltd.))

(Average diameter 16nm, apparent specific gravity 90g / liter of primary particles)

Ethanol 89 parts by mass

The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton-Gaulin to obtain a fine particle dispersion.

<Particulate addition liquid>

Cellulose ester (average acetyl group substitution degree 2.23, Mn = 140000) was added to the dissolution tank containing methylene chloride, and it melt | dissolved completely by heating, This was filtered using Azumi Rossi No. 244 by Azumi Rossi Co., Ltd. product. . The fine particle dispersion was slowly added thereto while sufficiently stirring the cellulose acetate solution after filtration. Further, the particles were dispersed in the attritor so that the particle diameter of the secondary particles became a predetermined value. This was filtered by FineMet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle addition liquid.

(Composition of the particulate addition liquid)

99 parts by mass of methylene chloride

4 mass parts of cellulose esters (above)

11 parts by mass of fine particle dispersion

The main doping of the following composition was prepared. First, methylene chloride and ethanol were added to the pressure-melting tank. The cellulose ester was added to the pressurized dissolution tank containing the solvent while stirring. It melt | dissolved completely, heating and stirring, and also the plasticizer was added and dissolved. This was filtered using Azumi Rossi No. 244 manufactured by Azumi Rossi Co., Ltd. to prepare a main dope.

<Composition of main dope>

Methylene chloride 390 parts by mass

80 parts by mass of ethanol

100 mass parts of cellulose esters (average acyl group substitution degree 2.48, acetyl group substitution degree 1.58, propionyl group substitution degree 0.90, Mn = 160000)

4 parts by mass of a glucose compound ((A-2) in [Formula 3])

100 mass parts of main dope and 5 mass parts of fine particle addition liquids are added, and it mixes enough by an inline mixer (Toray static type internal tube mixer Hi-Mixer, SWJ), and it is then uniform to a 2 m wide stainless steel band support body using a belt casting apparatus. It was flexible. On the stainless steel band support, the solvent was evaporated until the amount of residual solvent became 110%, and it peeled from the stainless steel band support. Subsequently, both ends of the web are gripped with a tenter and stretched at 42% in the width direction at 185 ° C, held for 4 seconds while maintaining the width after the completion of stretching, and the tension in the width direction is released to release the width maintenance, Furthermore, it conveyed for 30 minutes in the 3rd drying zone set to 125 degreeC, and dried, and produced the optical compensation film C12 which has a knurling of 1.49 m in width and 1 cm in width at the edge part in winding length 4000 m. The film thickness of this optical compensation film C12 was 68 micrometers. In-plane retardation value Ro of this optical compensation film C11 was 70 nm, and thickness direction retardation value Rt was 240 nm.

(Production of optical compensation film C13)

The pellet of the thermoplastic resin (brand name "Zenoa 1420", the Nippon Xeon company make, norbornene resin) was melt | dissolved with the extruder, it supplied to the die for extrusion, and the original film was shape | molded.

Subsequently, the original film was extended | stretched by extending | stretching temperature 170 degreeC, and draw ratio 1.01 times with the tenter stretching machine, and the long optical compensation film C13 with a film thickness of 20 micrometers was obtained. In-plane retardation value Ro of this optical compensation film C11 was 2 nm, and thickness direction retardation value Rt was 10 nm.

(Production of Polarizing Plates P21 to 27)

Polarizing plates P21-25 were produced like P1, P26, and 27 similarly to P3. However, about the optical compensation film C6, it bonded together so that the surface on which the adhesion facilitation process was performed may become a polyvinyl alcohol side. Table 6 shows the correspondence between the film used as the protective film, the optical compensation film, and the polarizer, and the polarizing plate.

(Fabrication of liquid crystal display device)

The polarizing plate of BRAVIA KDL-46HX800 manufactured by SONY Co., Ltd., which is VA mode, was peeled off, and the polarizing plate produced above was bonded to the panel by the combination shown in Table 7 so as to have the configuration of FIG. 1, and the liquid crystal display device (2-1) To 2-9) were produced and the following evaluation was performed. The liquid crystal cell of this liquid crystal display device is a cell of a COA type liquid crystal display device in which a color filter and a driving thin film transistor are arranged on one side of a transparent substrate, and are transmitted to the backlight unit in a direction orthogonal to the absorption axis of the polarizer 1. The reflection type brightness improving film which has an axis is inserted.

(Stain evaluation)

A black display was displayed on the screen in the state where the backlight was turned on, and luminance unevenness was evaluated by visual observation according to the following criteria.

◎: 0 to 2 of 10 stains can be confirmed

○: 3 to 5 of 10 stains can be confirmed

X: The stain | clear | clear_clear so that 6-10 of 10 stain | stain can be confirmed

The results of the evaluation are shown in Table 7.

As is clear from the evaluation results shown in Table 7, it can be seen that the liquid crystal display device using the polarizing plate of the present invention is excellent enough to hardly confirm luminance unevenness.

In addition, about the liquid crystal display device 2-9 of the comparative example, before performing uneven | corrugated evaluation, the light leakage of the front side at the time of black display was too large, and it did not function as a display apparatus.

The elongate polarizing plate of this invention can be used for manufacture of the liquid crystal display device using the polarizing plate for large liquid crystal display devices, such as a television and a monitor, and the said elongate polarizing plate.

1: Reflective type brightness enhancement film 1 2: Transparent protective film 1
3: polarizer 1 4: optical compensation film 1
5 liquid crystal cell 6 optical compensation film 2
7: polarizer 2 8: transparent protective film 2
a: transmission axis b: absorption axis
c: slow axis F: front (viewer's side)
R: Rear (back light side)

Claims (4)

At least the elongate transparent protective film, the polarizer, and the optical compensation film are elongate polarizing plates which are laminated in this order, the polarizer has an absorption axis in the width direction, and the Nz coefficient of the polarizer is within the range of 1.05 to 1.20. Moreover, the film thickness (d) of the said optical compensation film exists in the range which satisfy | fills following formula (1), The elongate shape polarizing plate characterized by the above-mentioned.
Equation (1): 10 μm <d <40 μm It is a liquid crystal display device which has a backlight, a liquid crystal cell, and a polarizing plate one by one on the viewing side and a backlight side of the said liquid crystal cell at least, The polarizing plate obtained by cutting the elongate polarizing plate of Claim 1 is equipped, and also the following requirements (a)-(c) is satisfied, The liquid crystal display device characterized by the above-mentioned.
(a) An optical compensation film (hereinafter referred to as "optical compensation film 1") of a polarizing plate obtained by cutting the elongated polarizing plate according to claim 1 as a polarizing plate (hereinafter referred to as "polarizing plate 1") on the backlight side of the liquid crystal cell. It is arrange | positioned so that it may become this liquid crystal cell side.
(b) The polarizing plate (hereinafter referred to as "polarizing plate 2") on the visual side of the liquid crystal cell is a polarizing plate in which a transparent protective film, a polarizer and an optical compensation film (hereinafter referred to as "optical compensation film 2") are laminated in this order. It is arrange | positioned so that the said optical compensation film 2 may be the said liquid crystal cell side.
(c) It arrange | positions so that the absorption axis of the said polarizing plate 1 and the said polarizing plate 2 may orthogonally cross. 3. The method of claim 2,
The said liquid crystal cell is a vertically-aligned liquid crystal cell, the said optical compensation film 2 contains the cellulose ester in which the average acyl group substitution degree exists in the range of 2.0-2.6, and also following formula (2)-formula (5) A liquid crystal display device, characterized by satisfying a relationship expressed by.
Equation (2): Ro (1) ≤ 5 nm
Equation (3): -10 nm < Rt (1) &lt; 20 nm
Equation (4): 60nm≤Ro (2) ≤80nm
Equation (5): 190nm≤Rt (2) ≤260nm
(However, in-plane retardation values Ro measured at a measurement wavelength of 589 nm at 23 ° C. and 55% RH of the optical compensation film 1 and the optical compensation film 2 are referred to as Ro (1) and Ro (2), respectively. In addition, thickness direction retardation value Rt is called Rt (1) and Rt (2), respectively, and Ro and Rt are defined by a following formula.
Formula (I): Ro = (n _x -n _y ) × d (nm)
Formula (II): Rt = {(n _x + n _y ) / 2-n _z } × d (nm)
In said formula, Ro represents the in-plane phase difference value in an optical compensation film, and Rt represents the phase difference of the thickness direction in a film. In addition, d represents the thickness of an optical compensation film, and n _x represents the largest (ground-axis direction) refractive index in surface of an optical compensation film. n _y represents the refractive index of the direction orthogonal to the slow axis in the optical compensation film plane, and n _z represents the refractive index of the optical compensation film in the thickness direction. In addition, measurement conditions are the same as the above.) The method according to claim 2 or 3,
A reflective luminance improving film is provided between the backlight and the polarizing plate 1, and the transmissive axis of the reflective luminance improving film and the absorption axis of the polarizer of the polarizing plate 1 are arranged so as to be perpendicular to each other. Display device.

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