JP2007058183A - Polarizing plate and image display device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image display device that prevents warpage of a panel and suppresses degradation in display performance. <P>SOLUTION: The image display device includes a panel comprising a glass or resin substrate, a top side layered body provided in the viewing side of the substrate, and a back layered body provided to the opposite side of the substrate, and is characterized in that: the top side layered body comprises a polarizer, a viewing side protective film disposed in the viewing side of the polarizer, and a substrate side protective film disposed on the opposite side of the polarizer; and the substrate side protective film is thinner than the viewing side protective film by 10 μm or more. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a polarizing plate and an image display device such as a thin display using the polarizing plate. In particular, the present invention relates to an image display device useful as a liquid crystal display device used for a monitor for a personal computer, a television, or the like.

  In recent years, many types of image display devices such as liquid crystal display devices, organic EL display devices, and PDPs have been developed. Although these uses are diverse, in recent years, developments for personal computer monitor applications and further TV applications have been promoted, and the enlargement of screens is progressing accordingly. At the same time as the screen has been enlarged, the overall thickness of the image display device has been reduced, and the panel having a thin glass or resin substrate constituting the image display device is likely to be warped, viewed from the front side (viewing side). The problem is that the center of the panel is dented and the edge is warped front side. When such warping occurs, the edge portions or four corners of the panel may come into contact with the housing, which adversely affects the screen display performance.

Panel warpage is the difference between the front and back sides of the glass or resin substrate that does not naturally warp, because various members laminated on the front side and back side cause expansion and contraction due to heating, moisture absorption / release, etc. This is because the balance between the front and back forces of the image display device is lost. In a normal image display device, the front side surface is open, while the back side is incorporated in a housing and is in a semi-sealed state. For this reason, there is a difference in heating and absorption / moisture release between the front-side laminate and the back-side laminate sandwiching the substrate, and there is also a difference in expansion / contraction.

  Taking a liquid crystal display device as an example, the liquid crystal display device includes a polarizing plate that creates polarized light on both sides of a liquid crystal cell in which liquid crystal is sealed in a glass substrate, and a retardation plate, an antireflection film, and a brightness enhancement film as necessary. Are stacked together, and the outer peripheral part is fixed with a fixed frame made of a metal plate called stainless steel called “bezel” to form a liquid crystal module, and this liquid crystal module is assembled and housed in a housing together with other components. Manufactured.

  When the power source of the liquid crystal display device is turned on, a difference in temperature or humidity may occur between the front side (viewing side) and the backlight side due to the temperature rising by the backlight. In this case, the temperature and humidity conditions at which the front-side laminate including the polarizing plate and the backlight-side laminate are exposed differ from each other with the liquid crystal cell as the boundary, and each laminate is considered to be affected by this. . When the warpage occurs, not only the edge portions or four corners of the panel come into contact with the housing, but also a display performance problem occurs due to the close contact with the backlight installed on the back surface. Furthermore, when a black display screen is used, the “corner unevenness” phenomenon in which the four corners of the panel (screen) leak light unevenly may cause a very large problem in display performance.

In order to improve panel warpage due to environmental changes, Patent Document 1 discloses a liquid crystal display device in which a polarizing plate made of a polarizer with a protective film is provided on both sides of a liquid crystal cell, and a brightness enhancement film is laminated on the polarizing plate on the back side. The film thickness of the protective film used for the front side polarizing plate and the protective film used for the back side polarizing plate are changed. However, when the thickness of the protective film on the viewing side of the laminate provided on the front side is reduced, there has been a problem that the optical performance is likely to deteriorate due to the deterioration of the polarizer due to humidity.
JP 2003-149634 A

  Accordingly, the present inventors consider solving the problems of the prior art, and provide an image display apparatus that prevents warping of the panel of the image display apparatus and suppresses a decrease in display performance. The purpose was. Another object of the present invention is to provide a polarizing plate that can prevent panel warpage when incorporated in an image display device and suppress deterioration in display performance.

The inventors of the present invention, when the liquid crystal display device is left for a certain period of time under high temperature and high humidity, and taken out under normal temperature and high humidity, the laminate member on the front side exposed to high temperature and high humidity particularly contracts, The balance between the force on the front and back of the panel is broken and warping has occurred, but the shrinkage of the laminated member on the front side is mainly caused by the shrinkage of the polarizer constituting the laminated member on the front side. I found it.
As a result of further investigation, in order to prevent warping, in order to suppress the contraction of the polarizer, the thickness of the protective film on the viewing side of the polarizer on the front side is increased, and in order to suppress the moment of warping, It has been found that the thickness of the protective film on the substrate side should be reduced to bring the polarizer closer to the substrate.

Specifically, the problem was solved by the following means.
[1] A polarizing plate in which at least one protective film is provided on each side of the polarizer, and the total thickness of the protective film provided on one side of the polarizer is provided on the opposite side of the polarizer. A polarizing plate characterized by being 10 μm or more thinner than the total thickness of the film.
[2] A polarizing plate in which one protective film is provided on one side of the polarizer and at least one protective film is provided on the opposite side of the polarizer, and the polarizing plate is provided on one side of the polarizer. A polarizing plate characterized in that the thickness of the protective film on the sheet is 10 μm or more thinner than the total thickness of the protective film provided on the opposite side of the polarizer.
[3] The polarizing plate according to [1] or [2], wherein at least one of the protective films constituting the polarizing plate is made of cellulose acylate.
[4] The cellulose acylate has a structure in which a hydroxyl group of a glucose unit constituting cellulose is substituted with an acyl group having 2 or more carbon atoms, and satisfies the following formulas (1) and (2): The polarizing plate according to [3], which is characterized in that
Formula (1): 2.0 ≦ DS ₂ + DS ₃ + DS ₆ ≦ 3.0
Formula (2): DS ₆ / (DS ₂ + DS ₃ + DS ₆ ) ≧ 0.315
[In the formula, DS ₂ represents the substitution degree of the hydroxyl group at the 2-position of the glucose unit constituting the cellulose with an acyl group, DS ₃ represents the substitution degree of the hydroxyl group at the 3-position with an acyl group, and DS ₆ represents the hydroxyl group at the 6-position. Represents the degree of substitution with an acyl group. ]
[5] The polarizing plate according to [4], wherein the acyl group is an acetyl group.
[6] The protective film made of cellulose acylate has a mixed fatty acid ester of cellulose as a main polymer component,
The mixed fatty acid ester of cellulose has a structure in which a hydroxyl group of cellulose is substituted with an acetyl group and an acyl group having 3 or more carbon atoms, and satisfies the following mathematical formulas (3) and (4): The polarizing plate according to [3].
Formula (3): 2.0 ≦ A + B ≦ 3.0
Formula (4): 0 <B
[In the formula, A represents the substitution degree of the acetyl group of cellulose acylate, and B represents the substitution degree of the acyl group having 3 or more carbon atoms. ]
[7] The polarizing plate according to [6], wherein the acyl group having 3 or more carbon atoms is a propionyl group or a butanoyl group.
[8] The polarizing plate according to [6] or [7], wherein the substitution degree of the hydroxyl group at the 6-position of cellulose in the cellulose acylate is 0.75 or more.
[9] The polarizing plate according to [1] or [2], wherein at least one of the protective films constituting the polarizing plate is made of a cyclic polyolefin.
[10] The total thickness of the protective film on one side of the polarizer is 30 μm to 50 μm, and the total thickness of the protective film on the opposite side of the polarizer is 70 μm to 150 μm. ] The polarizing plate as described in any one of.

[11] An image display device comprising a panel comprising a substrate made of glass or resin, a front side laminate provided on the viewing side of the substrate, and a back side laminate provided on the opposite side of the substrate,
The front side laminate was installed such that the total thickness of the protective film provided on the substrate side of the polarizer was 10 μm or more thinner than the total thickness of the protective film provided on the viewing side of the polarizer [1] to [10] An image display device comprising the polarizing plate according to any one of [10].
[12] The image display device according to [11], wherein the panel is rectangular or square, and one side is 10 cm to 500 cm.
[13] The image display device according to [11] or [12], wherein a front surface of the panel is open and a back surface of the panel is closed by a casing.
[14] The image display device according to any one of [11] to [13], wherein the substrate has a liquid crystal cell, and the back-side laminate has an optical compensation film.
[15] The image display device according to any one of [11] to [14], wherein a VA mode or IPS mode liquid crystal display mode is used.

  The image display apparatus of the present invention can maintain excellent display performance because the warpage of the panel is suppressed. Further, if the polarizing plate of the present invention is incorporated in an image display device, it is possible to suppress warping of the panel and maintain excellent display performance.

  Hereinafter, the polarizing plate and the image display device of the present invention will be described in detail. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value. In this specification, “parallel” means that the angle between the two directions is 0 ° ± 1 °, and “vertical” and “orthogonal” means that the angle between the two directions is 90 ° ± 1 °.

(Configuration of image display device)
The image display device of the present invention includes a panel having a substrate made of glass or resin, a front side laminate provided on the viewing side of the substrate, and a back side laminate provided on the opposite side of the substrate. The front side laminate has a polarizing plate, a viewing side protective film provided on the viewing side of the polarizing plate, and a substrate side protective film provided on the opposite side of the polarizing plate. Further, the thickness of the substrate-side protective film is characterized by being 10 μm or thinner than the thickness of the viewing-side protective film.
The panel which comprises the image display apparatus of this invention may be provided with the other optical film and the functional layer as needed. Further, it is preferable that the front surface of the panel is open and the back surface is closed by a housing. A configuration example of such an image display apparatus of the present invention is shown in FIG. 1 (the upper side is the viewer side).

  In the following description, a liquid crystal display device will be described as a main example as an image display device, but the image display device of the present invention is not limited to a liquid crystal display device.

The liquid crystal display device has a structure in which polarizing plates are disposed on both sides of a liquid crystal cell serving as a substrate, and various optical elements such as a retardation film, an antireflection film, and a brightness enhancement film are laminated as necessary. The substrate referred to in the present invention corresponds to a liquid crystal cell in the case of a liquid crystal display device, and the laminate corresponds to various optical elements such as a polarizing plate, a retardation film, an antireflection film, and a brightness enhancement film.
In general, a liquid crystal display device is a liquid crystal module in which the outer periphery of the liquid crystal panel is fixed with a fixed frame made of a metal plate such as stainless steel called a “bezel”, and the liquid crystal module is assembled and housed in a casing together with other components. Manufactured. The present invention is also used in the same configuration.

(substrate)
The substrate constituting the image display device of the present invention is made of glass or resin (plastic). The glass or resin may contain an additive, and the substrate may hold components other than glass or resin. In the present invention, the “substrate” refers to a plate that holds a liquid crystal in a liquid crystal display device, and a plate that holds a light emitter in an organic EL display device or PDP.
For example, when the substrate is a liquid crystal cell of a liquid crystal display device, glass or resin usually used for this purpose can be adopted as a constituent element. Then, liquid crystal can be sealed between cell substrates made of glass or resin. Moreover, a transparent conductive film can be provided on both surfaces of the liquid crystal, and a color filter can be provided on the front side (viewing side) of the transparent conductive film. From the viewpoint of thinning the liquid crystal display device, the substrate preferably has a thickness of 1 mm or less, more preferably 0.7 mm or less, and most preferably 0.5 mm or less. Although there is no particular limitation on the size, the liquid crystal panel is likely to warp when the area is large. Therefore, the present invention is particularly effective when used in a large-screen liquid crystal display device.

  Here, the material of the resin substrate is not particularly limited as long as it has transparency and mechanical strength, and all conventionally known ones can be used. Examples of the resin that forms the resin substrate include thermoplastic resins such as polycarbonate, polyarylate, polyethersulfone, polyester, polysulfone, polymethyl methacrylate, polyetherimide, and polyamide, epoxy resin, unsaturated polyester, and polydiallyl. Examples thereof include thermosetting resins such as phthalate and polyisobornyl methacrylate. 1 type, or 2 or more types can be used for this resin, and it can also be used as a copolymer and a mixture with another component.

(Polarizer)
Next, the polarizing plate which comprises a laminated body in a liquid crystal display device is demonstrated.
The polarizing plate of this invention is used for the front side laminated body of the liquid crystal display device of this invention. The polarizing plate of the present invention is a polarizing plate in which at least one protective film is provided on both sides of the polarizer, and the total thickness of the protective film provided on one side of the polarizer is provided on the opposite side of the polarizer. It is characterized by being 10 μm or thinner than the total thickness of the protective film. Among them, a polarizing plate in which one protective film is provided on one side of the polarizer and at least one protective film is provided on the opposite side of the polarizer, and 1 is provided on one side of the polarizer. A polarizing plate characterized in that the thickness of the protective film on the sheet is 10 μm or more thinner than the total thickness of the protective film provided on the opposite side of the polarizer.
In the polarizing plate of the present invention, the total thickness of the protective film provided on one side of the polarizer is preferably 20 μm or thinner than the total thickness of the protective film provided on the opposite side of the polarizer, more preferably 30 μm or thinner. . Further, the total thickness of the protective film provided on one side of the polarizer is preferably 50 μm or less, and particularly preferably 30 μm to 40 μm. At this time, the total thickness of the protective film provided on the opposite side of the polarizer is preferably 70 μm or more, particularly preferably 80 μm to 150 μm.

  As a polarizing plate constituting the liquid crystal display device of the present invention, for example, a polyvinyl alcohol (PVA) film is dyed with iodine having a dichroism or a dichroic dye, stretched and oriented, and then crosslinked and dried. An absorptive polarizing plate produced by bonding a polarizer and a protective film such as a triacetyl cellulose (TAC) film can be preferably used. The polarizer is preferably excellent in light transmittance and degree of polarization. The light transmittance is preferably 30% to 50%, more preferably 35% to 50%, and most preferably 40% to 50%. The degree of polarization is preferably 90% or more, more preferably 95% or more, and most preferably 99% or more. When the transmittance is 30% or less or the degree of polarization is 90% or less, the brightness and contrast of the image display device are low, and the display quality is deteriorated. The thickness of the polarizer is preferably 1 to 50 μm, more preferably 1 to 30 μm, and most preferably 8 to 25 μm.

  In the present invention, the adhesion treatment between the polarizer and the protective film is not particularly limited. For example, an adhesive made of a vinyl alcohol polymer, boric acid, borax, glutaraldehyde, melamine, oxalic acid, etc. This can be carried out through an adhesive comprising at least a water-soluble crosslinking agent of the vinyl alcohol polymer. In particular, it is preferable to use a polyvinyl alcohol-based adhesive because it has the best adhesion to the polyvinyl alcohol-based film. Such an adhesive layer can be formed as a coating / drying layer of an aqueous solution, but other additives and a catalyst such as an acid can be blended as necessary when preparing the aqueous solution.

  As a material for forming the protective film, a polymer excellent in optical performance transparency, mechanical strength, thermal stability, moisture shielding property, isotropy and the like is preferable. Examples include polycarbonate polymers, polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, acrylic polymers such as polymethyl methacrylate, and styrene polymers such as polystyrene and acrylonitrile / styrene copolymer (AS resin). Polyolefins such as polyethylene and polypropylene, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers, polyethersulfone polymers , Polyether ether ketone polymers, polyphenylene sulfide polymers, vinylidene chloride polymers, vinyl alcohol polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene polymers, epoxy polymers, or polymers mixed with the above polymers Take as an example. In addition, the protective film used in the present invention can be formed as a cured layer of an acrylic, urethane, acrylic urethane, epoxy, silicone, or other ultraviolet curable or thermosetting resin.

  In the present invention, as a polymer for forming a protective film, cellulose acylate (eg, cellulose acetate, cellulose diacetate), polyolefin, cyclic polyolefin (eg, polymer of norbornene (hereinafter also referred to as “norbornene polymer”)) Poly (meth) acrylic acid esters (eg, polymethyl methacrylate), polycarbonate and polysulfone are used. Commercially available polymers (for norbornene polymers, Arton (manufactured by JSR), Zeonore (manufactured by Nippon Zeon), etc.) are preferred. Examples of the norbornene-based polymer include a ring-opening polymer of norbornenes (for example, norbornene, a compound in which norbornene is condensed with a cycloolefin ring), a hydrogenated product thereof, an addition copolymer of norbornene and ethylene, and the like. Can be mentioned.

  The protective film used in the present invention may be formed by thermally melting a thermoplastic polymer resin, or may be formed by solution film formation (solvent casting method) from a solution in which a polymer is uniformly dissolved. . In the case of hot melt film formation, various additives (for example, a compound that reduces optical anisotropy, a wavelength dispersion adjusting agent, an ultraviolet ray preventing agent, a plasticizer, a deterioration preventing agent, fine particles, an optical property adjusting agent, etc.) are heated. It can be added at the time of melting. On the other hand, when the protective film is prepared from a solution, the polymer solution (hereinafter referred to as a dope) includes various additives (for example, a compound that reduces optical anisotropy, wavelength dispersion) depending on the application in each preparation step. Adjusters, ultraviolet inhibitors, plasticizers, deterioration inhibitors, fine particles, optical property adjusters, and the like). Further, the timing of the addition may be at any stage of the dope preparation process or at the end of the dope preparation process.

(Front side laminate including polarizing plate)
The front side laminate of the liquid crystal display device includes a polarizing plate, and may further include an optical member bonded to the viewing side of the polarizing plate and the liquid crystal cell side (substrate side).
An optical compensation film may be used as necessary for the protective film on the liquid crystal cell side of the polarizing plate (substrate-side protective film). The optical compensation film generally refers to an optical material that compensates for a viewing angle in an oblique direction of a liquid crystal display device, and is synonymous with a retardation plate, an optical compensation sheet, and the like. The optical compensation film may be an integral type in which the protective film itself of the polarizing plate has optical performance, for example, a triacetyl cellulose acylate film having optical compensation performance to form a protective film for a polarizer. For example, a triacetyl cellulose film coated with a discotic liquid crystal and then integrated with a polarizing plate may be used.
When the optical compensation film is provided on the back-side laminate, the protective film on the liquid crystal cell side (substrate-side protection film) of the polarizing plate of the front-side laminate has a small refractive index anisotropy (different in the surface direction and thickness direction). A protective film may not be used.

  In any case, in the present invention, the thickness of the protective film (substrate side protective film) on the liquid crystal cell side of the polarizing plate of the front side laminate is such that the protective film on the visual side of the polarizing plate of the front side laminate (visible side protective film). Further, it is characterized by being made thinner by 10 μm or more. The substrate side protective film is preferably thinner than the visible side protective film by 20 μm or more, preferably 30 μm or more. The thickness of the substrate side protective film is preferably 50 μm or less, particularly preferably 30 μm to 40 μm. At this time, the thickness of the viewing side protective film is preferably 70 μm or more, and particularly preferably 80 μm to 150 μm.

  In some cases, a hard coat film, an antireflection film, an antiglare film, or the like is appropriately provided on the viewing side surface of the polarizing plate by bonding or surface treatment. The hard coat film or hard coat treatment is performed for the purpose of preventing scratches on the polarizing plate surface, for example, a cured film excellent in hardness, slipperiness, etc. due to an appropriate ultraviolet curable resin such as a silicone type, It can be formed by a method of adding to the surface of the transparent protective film. The anti-reflection film or anti-reflection treatment (anti-reflection) is applied for the purpose of preventing the reflection of external light on the polarizing plate surface, and the anti-glare film or anti-glare treatment (anti-glare) is the surface of the panel (screen). In order to prevent external light from being reflected and obstructing the visibility of transmitted light from the panel, for example, a roughening method such as a sandblasting method or an embossing method, or transparent fine particles are contained. It can be formed by providing a fine concavo-convex structure on the surface of the protective film by an appropriate method such as a method of coating a coating liquid.

(Back side laminate including polarizing plate)
The back side laminate of the liquid crystal display device includes a polarizing plate, and may further include an optical member bonded to the liquid crystal cell side and the backlight side of the polarizing plate.
If necessary, an optical compensation film may be used on the liquid crystal cell side of the polarizing plate, and a diffusion sheet, a brightness enhancement film, or the like may be used on the backlight side. These members may be bonded together using a pressure-sensitive adhesive, and the pressure-sensitive adhesive at this time is also included in the back side laminate. However, if the diffusion sheet, the brightness enhancement film, and the like are arranged on the backlight side and are not directly bonded to the back side polarizing plate, they are not included in the back side laminate in the present invention.

  The optical compensation film of the back side laminate may be of a type that is integrated with the same polarizing plate as that described for the front side laminate, or may be a laminate of a plurality of sheets. As the optical compensation film to be bonded, a polymer film is mainly preferably used. For example, bi-directional stretching such as a birefringent polymer film stretched biaxially in the plane direction, or a tilted orientation polymer film with a controlled refractive index in the thickness direction stretched uniaxially in the plane direction and stretched in the thickness direction A film or the like is used. Furthermore, an inclined alignment film is also used. For example, a heat-shrinkable film may be bonded to the polymer film, and the polymer film may be stretched and / or shrunk under the action of the shrinkage force by heating, or the liquid crystal polymer may be obliquely oriented.

  Generally, the members constituting the layers on the viewing side and the liquid crystal cell side are bonded together using an adhesive. The adhesive layer at this time is also included in each laminate.

  The pressure-sensitive adhesive layer can be formed of an appropriate pressure-sensitive adhesive such as an acrylic type. From the viewpoints of preventing foaming and peeling phenomena due to moisture absorption, and reducing optical characteristics due to differences in thermal expansion, etc., an adhesive layer having a low moisture absorption rate and excellent heat resistance is preferred. The pressure-sensitive adhesive layer may be provided as necessary, and in the present invention, for example, it can be provided as necessary for adhesion between the optical compensation film and the protective film, adhesion between the liquid crystal cell and the protective film, or the like.

(Panel size)
The size of each layer used in the image display device is equal to the size of the panel (screen). Although depending on the panel size of the image display device, the length of the long side is preferably 10 to 500 cm from the viewpoint of practical size and manufacturing. More preferably, it is 20-500 cm, More preferably, it is 30-500 cm, Most preferably, it is 50-500 cm. Although there is no particular limitation on the size, the liquid crystal panel is likely to warp when the area is large. Therefore, the present invention is particularly effective when used in a large-screen liquid crystal display device.

(Panel warpage)
The warpage of the panel in the present invention is measured when 20 minutes have passed since the panel was left at a temperature of 50 ° C. and a relative humidity of 95% for 50 hours and then moved to an environment of a temperature of 25 ° C. and a relative humidity of 60%. . The warpage is measured by placing the panel on a horizontal table. Of the outer edge of the panel that is lifted from the horizontal base due to warpage, the height of the lift of the portion with the greatest warpage is measured as the amount of warpage (mm). The warpage rate (w / L) is obtained by dividing the warpage amount w (mm) by the length L (mm) in the long side direction of the panel. The warpage rate in the present invention preferably satisfies w / L ≦ 0.006, and more preferably satisfies w / L ≦ 0.005.

(Image display device)
As described above, the image display device of the present invention includes many types of image display devices such as a liquid crystal display device, an organic EL display device, and a PDP.

  The liquid crystal display device which is an example of the image display device of the present invention can be achieved by using liquid crystal cells of various display modes. Display modes include IPS (In-Plane Switching), VA (Vertical Aligned), TN (Twisted Nematic), OCB (Optically Compensated Bend), STN (Super Twisted Nematic), ECB (Electrically Controlled Birefringence), FLC (Ferroelectric Liquid Crystal). ), AFLC (Anti-ferroelectric Liquid Crystal), and HAN (Hybrid Aligned Nematic) have been proposed. In addition, a display mode in which the above display mode is oriented and divided has been proposed.

  In order to more effectively prevent panel warpage and corner unevenness due to warpage, the absorption axis of the polarizing plate is bonded in parallel or perpendicular to the long side direction of the panel (usually the horizontal direction of the screen). It is desirable to adopt. Display modes that generally employ such bonding include IPS and VA. In the liquid crystal display device of the present invention, liquid crystal cells of these display modes can be desirably used.

(Cellulose acylate)
Next, the cellulose acylate preferably used in the present invention will be described in detail. In the present invention, two or more different cellulose acylates may be mixed and used.

  Next, the cellulose acylate of the present invention produced from the above-mentioned cellulose will be described. The cellulose acylate of the present invention is obtained by acylating a hydroxyl group of cellulose, and the substituent can be any acetyl group having 2 carbon atoms to 22 carbon atoms. In the cellulose acylate of the present invention, the degree of substitution of cellulose with a hydroxyl group is not particularly limited, but the degree of binding of acetic acid and / or a fatty acid having 3 to 22 carbon atoms substituted with a hydroxyl group of cellulose is measured and substituted by calculation. You can get a degree. As a measuring method, it can carry out according to ASTM D-817-91.

  Among the acetic acid substituted for the hydroxyl group of cellulose and / or the fatty acid having 3 to 22 carbon atoms, the acyl group having 2 to 22 carbon atoms is not particularly limited and may be an aliphatic group or an allyl group. A mixture of the above may also be used. These are, for example, cellulose alkylcarbonyl esters, alkenylcarbonyl esters, aromatic carbonyl esters, aromatic alkylcarbonyl esters, and the like, each of which may further have a substituted group. As these preferable acyl groups, acetyl group, propionyl group, butanoyl group, heptanoyl group, hexanoyl group, octanoyl group, decanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, hexadecanoyl group, octadecanoyl group , Iso-butanoyl group, t-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, t-butanoyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like are preferable, and acetyl group, propionyl group, butanoyl group are preferable. Groups are more preferred.

  Glucose units having β-1,4 bonds constituting cellulose have free hydroxyl groups at the 2nd, 3rd and 6th positions. Cellulose acylate is a polymer obtained by esterifying some or all of these hydroxyl groups with acyl groups. The degree of acyl substitution means the proportion of cellulose esterified at each of the 2nd, 3rd and 6th positions, and the hydroxyl group is 100% esterified at each of the 2nd, 3rd and 6th positions. In this case, the substitution degree is 1, and when all hydroxyl groups at the 2-position, 3-position and 6-position are 100% esterified, the substitution degree is 3. That is, the sum of the substitution degrees (A + B, which is also called the total substitution degree) is 3. Similarly, the degree of acetyl substitution, the degree of propionyl substitution, and the degree of butanoyl substitution mean the proportions of cellulose acetylated, propionylated, and butanoylated, respectively.

In the present invention, the substitution degree of the hydroxyl group at the 2-position of the glucose unit of the cellulose acylate film with DS2 is DS2, the substitution degree with the acyl group of the hydroxyl group at position 3 is DS3, and the substitution degree with the acyl group of the hydroxyl group at position 6 is DS6. It is preferable that the following mathematical formulas (1) and (2) are satisfied.
Formula (1): 2.0 ≦ DS2 + DS3 + DS6 ≦ 3.0
Formula (2): DS6 / (DS2 + DS3 + DS6) ≧ 0.315

  Among the above, DS2 + DS3 + DS6 is preferably 2.20 to 3.00, and particularly preferably 2.40 to 2.85. DS6 / (DS2 + DS3 + DS6) is preferably 0.316 or more, and more preferably 0.317 or more. The upper limit is preferably 0.36, and more preferably 0.35.

  The cellulose acylate used in the present invention is a mixed fatty acid ester of cellulose obtained by substituting a hydroxyl group of cellulose with an acetyl group and an acyl group having 3 or more carbon atoms, and has a degree of substitution with the hydroxyl group of cellulose. A cellulose acylate satisfying the following mathematical formulas (3) and (4) can also be preferably used.

Formula (3): 2.0 ≦ A + B ≦ 3.0
Formula (4): 0 <B
Here, in the formula, A and B represent the substitution degree of the acyl group substituted by the hydroxyl group of cellulose, A is the substitution degree of the acetyl group, and B is the substitution degree of the acyl group having 3 or more carbon atoms.

In the present invention, the total substitution degree (A + B) of hydroxyl groups A and B is preferably 2.00 to 3.00, more preferably 2.20 to 3, as shown in the above formula (3). 0.00, particularly preferably 2.40 to 2.85. Further, the substitution degree of B is preferably a value exceeding 0, more preferably 0.5 to 2.5, and even more preferably 0.6 to 2.0, as shown in the above formula (4). And particularly preferably 0.7 to 1.8.
If A + B is 2.0 or more, since hydrophilicity is weak, there exists a tendency which is hard to receive to the influence of environmental humidity.
When B is 0 and becomes cellulose acetate, it tends to be relatively susceptible to environmental humidity.
Further, B is preferably 28% or more of the substitution degree of the 6-position hydroxyl group, more preferably 30% or more is the substitution degree of the 6-position hydroxyl group, more preferably 31% or more, and particularly preferably 32% or more. preferable.
Furthermore, the sum of the substitution degrees of A and B of the 6-position hydroxyl group of cellulose acylate is preferably 0.75 or more, more preferably 0.80 or more, and particularly preferably 0.85 or more. With these cellulose acylate films, a solution for preparing a film having preferable solubility and filterability can be produced, and a good solution can be produced even in a non-chlorine organic solvent. Furthermore, it becomes possible to produce a solution having a low viscosity and good filterability.

  The acyl group having 3 or more carbon atoms may be an aliphatic group or an aromatic hydrocarbon group, and is not particularly limited. These are, for example, cellulose alkylcarbonyl esters, alkenylcarbonyl esters, aromatic carbonyl esters, aromatic alkylcarbonyl esters, and the like, each of which may further have a substituted group. As these preferable B, propionyl group, butanoyl group, keptanoyl group, hexanoyl group, octanoyl group, decanoyl group, dodecanoyl group, tridecanoyl group, tetradecanoyl group, hexadecanoyl group, octadecanoyl group, iso-butanoyl group , T-butanoyl group, cyclohexanecarbonyl group, oleoyl group, benzoyl group, naphthylcarbonyl group, cinnamoyl group and the like. Among these, a propionyl group, a butanoyl group, a dodecanoyl group, an octadecanoyl group, a t-butanoyl group, an oleoyl group, a benzoyl group, a naphthylcarbonyl group, a cinnamoyl group and the like are preferable. Particularly preferred are a propionyl group and a butanoyl group. In the case of a propionyl group, the substitution degree B (propionyl substitution degree) is preferably 1.3 or more.

  Specific examples of cellulose acylate include cellulose acetate propionate and cellulose acetate butyrate.

[Method of synthesizing cellulose acylate]
The basic principle of the cellulose acylate synthesis method is described in Mita et al., Wood chemistry, 180-190 (Kyoritsu Shuppan, 1968). A typical synthesis method is a liquid phase acetylation method using a carboxylic acid anhydride-acetic acid-sulfuric acid catalyst.
Specifically, cellulose raw materials such as cotton linter and wood pulp are pretreated with an appropriate amount of acetic acid, and then put into a pre-cooled carboxylated mixed solution to be esterified to complete cellulose acylate (2nd, 3rd and 6th). The total degree of acyl substitution at the position is approximately 3.00). The carboxylated mixed solution generally contains acetic acid as a solvent, carboxylic anhydride as an esterifying agent, and sulfuric acid as a catalyst. The carboxylic anhydride is usually used in a stoichiometric excess over the sum of the cellulose that reacts with it and the water present in the system. After completion of the esterification reaction, a neutralizing agent (for example, calcium, magnesium, iron, aluminum or zinc) is used for hydrolysis of excess carboxylic anhydride remaining in the system and neutralization of a part of the esterification catalyst. Of carbonate, acetate or oxide). Next, the obtained complete cellulose acylate is saponified and aged by maintaining it at 50 to 90 ° C. in the presence of a small amount of an acetylation reaction catalyst (generally, remaining sulfuric acid) to obtain a desired acyl substitution degree and polymerization. The cellulose acylate having a degree is changed. When the desired cellulose acylate is obtained, the catalyst remaining in the system is completely neutralized with the neutralizing agent as described above, or in water or dilute sulfuric acid without neutralization. The cellulose acylate solution is added (or water or dilute sulfuric acid is added to the cellulose acylate solution), the cellulose acylate is separated, washed and stabilized, and the like. Can be obtained.

In the cellulose acylate film, the main polymer component constituting the film is preferably composed of the specific cellulose acylate. In the present application, “main” means 55% by mass or more (preferably 70% by mass or more, more preferably 80% by mass or more) of the polymer component. When the polarizing plate of the present invention is produced, cellulose acylate containing a mixed fatty acid ester of cellulose having a structure in which a hydroxyl group of cellulose is substituted with an acetyl group and an acyl group having 3 or more carbon atoms as a main polymer component is used. Is mentioned as a preferred embodiment.
Cellulose acylate is preferably used in the form of particles. 90% by mass or more of the particles to be used preferably have a particle diameter of 0.5 to 5 mm. Moreover, it is preferable that 50 mass% or more of the particle | grains to be used have a particle diameter of 1-4 mm. The cellulose acylate particles preferably have a shape as close to a sphere as possible.
The degree of polymerization of cellulose acylate preferably used in the present invention is a viscosity average degree of polymerization, preferably 200 to 700, more preferably 250 to 550, still more preferably 250 to 400, and particularly preferably 250 to 350. . The average degree of polymerization can be measured by Uda et al.'S intrinsic viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Society, Vol. 18, No. 1, pages 105-120, 1962). Further details are described in JP-A-9-95538.

When the low molecular component is removed, the average molecular weight (polymerization degree) is increased, but the viscosity is lower than that of ordinary cellulose acylate. Therefore, the cellulose acylate from which the low molecular component is removed is useful. . Cellulose acylate having a small amount of low molecular components can be obtained by removing low molecular components from cellulose acylate synthesized by a usual method. The removal of the low molecular component can be carried out by washing the cellulose acylate with an appropriate organic solvent. In addition, when manufacturing a cellulose acylate with few low molecular components, it is preferable to adjust the sulfuric acid catalyst amount in an acetylation reaction to 0.5-25 mass parts with respect to 100 mass parts of cellulose acylates. When the amount of the sulfuric acid catalyst is within the above range, cellulose acylate that is preferable in terms of molecular weight distribution (uniform molecular weight distribution) can be synthesized. When used in the production of cellulose acylate, the water content is preferably 2% by mass or less, more preferably 1% by mass or less, and particularly 0.7% by mass or less. In general, the cellulose acylate contains water and generally has a water content of 2.5 to 5% by mass. In order to make this moisture content, it is preferable to dry, and the method will not be specifically limited if it becomes the target moisture content.
The raw material cotton of cellulose acylate and the synthesis method thereof are the raw material cotton described in detail on pages 7 to 12 of the Japan Institute of Invention Technology (Publication No. 2001-1745, published on March 15, 2001, Japan Society of Invention). A synthesis method can be adopted.

The cellulose acylate film of the present invention can be obtained by forming a film using a solution prepared by dissolving the specific cellulose acylate and, if necessary, an additive in an organic solvent.
[Additive]
In the present invention, examples of the additive that can be used in the cellulose acylate solution include a plasticizer, an ultraviolet absorber, a deterioration inhibitor, a retardation (optical anisotropy) developer, fine particles, a peeling accelerator, and red. An external absorbent can be used, and in the present invention, it is preferable to use a retardation developer. Moreover, it is preferable to use 1 or more types of a plasticizer, a ultraviolet absorber, and a peeling accelerator.
They may be solid or oily. That is, the melting point and boiling point are not particularly limited. For example, ultraviolet absorbers having melting points of 20 ° C. or lower and 20 ° C. or higher can be mixed and used, and plasticizers can also be mixed and used, for example, as described in Japanese Patent Application Laid-Open No. 2001-151901. .

  As the ultraviolet absorber, any type can be selected according to the purpose, and a salicylic acid ester-based, benzophenone-based, benzotriazole-based, benzoate-based, cyanoacrylate-based, nickel complex-based absorber or the like is used. Preferred are benzophenone series, benzotriazole series, and salicylic acid ester series. Examples of benzophenone ultraviolet absorbers include 2,4-dihydroxybenzophenone, 2-hydroxy-4-acetoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2′-di-hydroxy-4-methoxybenzophenone, 2, 2′-di-hydroxy-4,4′-methoxybenzophenone, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy-4- (2-hydroxy-3- And methacryloxy) propoxybenzophenone. Examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-3′-tert-butyl-5′-methylphenyl) -5-chlorobenzotriazole, 2- (2′-hydroxy-5′-tert- Butylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-amylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) ) -5-chlorobenzotriazole, 2- (2′-hydroxy-5′-tert-octylphenyl) benzotriazole, and the like. Examples of salicylic acid esters include phenyl salicylate, p-octylphenyl salicylate, and p-tert-butylphenyl salicylate. Among these exemplified UV absorbers, 2-hydroxy-4-methoxybenzophenone, 2,2′-di-hydroxy-4,4′-methoxybenzophenone, 2- (2′-hydroxy-3′-tert-butyl), among others. -5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-5'-tert-butylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert -Amylphenyl) benzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-butylphenyl) -5-chlorobenzotriazole is particularly preferred.

  As the ultraviolet absorber, it is preferable to use a combination of a plurality of absorbers having different absorption wavelengths because a high blocking effect can be obtained in a wide wavelength range. From the viewpoint of preventing deterioration of the liquid crystal, the ultraviolet absorbent for liquid crystal is preferably excellent in the ability to absorb ultraviolet light having a wavelength of 370 nm or less, and has little absorption of visible light having a wavelength of 400 nm or more from the viewpoint of liquid crystal display properties. Particularly preferred ultraviolet absorbers are the benzotriazole compounds, benzophenone compounds, and salicylic acid ester compounds mentioned above. Among these, a benzotriazole-based compound is preferable because unnecessary coloring with respect to the cellulose ester is small.

  As for the UV absorber, JP-A-60-235852, JP-A-3-199201, JP-A-51907073, JP-A-5-194789, JP-A-5-271471, JP-A-6-107854, JP-A-6-107854. 118233, 6-148430, 7-11056, 7-11055, 7-11056, 8-29619, 8-239509, JP-A-2000-204173 These compounds can also be used.

  The addition amount of the ultraviolet absorber is preferably 0.001 to 5% by mass, preferably 0.01 to 1% by mass with respect to the cellulose acylate from the viewpoint of the addition effect and suppressing the ultraviolet absorber from bleeding out to the film surface. Is more preferable.

  Further, the ultraviolet absorber may be added simultaneously with the dissolution of cellulose acylate, or may be added to the dope after dissolution. In particular, a mode in which an ultraviolet absorbent solution is added to the dope immediately before casting using a static mixer or the like is preferable because the spectral absorption characteristics can be easily adjusted.

  The deterioration preventing agent prevents cellulose triacetate and the like from deteriorating and decomposing. Examples of the deterioration preventing agent include butylamine, hindered amine compounds (JP-A-8-325537), guanidine compounds (JP-A-5-271471), benzotriazole-based UV absorbers (JP-A-6-235819), and benzophenone-based compounds. There are compounds such as UV absorbers (JP-A-6-118233).

  The plasticizer is preferably a phosphate ester or a carboxylic acid ester. Specific examples of the plasticizer include triphenyl phosphate (TPP), tricresyl phosphate (TCP), cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, dimethyl phthalate (DMP), Diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), diphenyl phthalate (DPP), diethyl hexyl phthalate (DEHP), triethyl O-acetylcitrate (OACTE), tributyl O-acetylcitrate (OACTB) , Acetyl triethyl citrate, acetyl tributyl citrate, butyl oleate, methyl acetyl ricinoleate, dibutyl sebacate, triacetin Tributyrin, butyl phthalyl butyl glycolate, ethyl phthalyl ethyl glycolate, methyl phthalyl ethyl glycolate, butyl phthalyl butyl glycolate may be preferably mentioned. Further, preferred plasticizers include (di) pentaerythritol esters, glycerol esters, and diglycerol esters.

  Examples of the peeling accelerator include citric acid ethyl esters. Furthermore, as an infrared absorber, the compound as described in Unexamined-Japanese-Patent No. 2001-194522 is mentioned, for example.

  These additives may be added at any stage in the dope preparation process, but may be performed by adding an additive addition process as the final preparation process of the dope preparation process. Furthermore, the amount of each material added is not particularly limited as long as the function is manifested. Moreover, when a cellulose acylate film is a multilayer, the kind and addition amount of the additive of each layer may differ. For example, although it describes in Unexamined-Japanese-Patent No. 2001-151902 etc., these are techniques conventionally known.

As for the elastic modulus of the cellulose acylate film of the present invention, the elastic modulus E (MD) in the casting (conveying) direction and the elastic modulus E (TD) in the casting width direction (vertical casting direction) are expressed by the following formula (5). ) And (6) are preferably satisfied. Furthermore, it is preferable that elastic modulus E (MD) and E (TD) satisfy | fill following numerical formula (7). The elastic modulus can be measured with a tensile tester (Strograph-R2 (Toyo Seiki)).
Formula (5): 1500 MPa ≦ E (MD) ≦ 3400 MPa
Formula (6): 1200 MPa ≦ E (TD) ≦ 3400 MPa
Expression (7): 0.5 ≦ E (MD) / E (TD) ≦ 2
The elastic modulus of the cellulose acylate film of the present invention can satisfy the above mathematical formula by selecting the kind and the addition amount of the plasticizer.
The effect of the elastic modulus E (MD) in the casting (conveying) direction and the elastic modulus E (TD) in the casting width direction (vertical casting direction) satisfying the above formulas (5) and (6) is as follows. It is as follows. When there is a change in the environment (humidity), a polarizing plate constituent part composed of an adhesive layer, a retardation film, a polarizer, a protective film and the like contracts and expands, and stress is generated between the parts. When this stress is well balanced in the constituent parts of the polarizing plate, the polarizing plate becomes a liquid crystal display device with little change in viewing angle characteristics even when there is a change in environmental humidity, and a preferable result is obtained.

  70-150 degreeC is preferable and, as for the glass transition point Tg of the cellulose acylate film of this invention, 80-135 degreeC is more preferable. The glass transition point Tg can be measured with a dynamic viscoelasticity measuring device (Vibron: DVA-225 (ITG Measurement Control Co., Ltd.)). The glass transition point can also be adjusted to the above range by appropriately selecting the type and amount of plasticizer. The cellulose acylate film of the present invention preferably has a glass transition point Tg within the above range from the viewpoint of process suitability for polarizing plate processing and liquid crystal display device assembly.

  Furthermore, about an additive, what is described in detail after 16 pages of invention association public technical bulletins (public technical number 2001-1745, March 15, 2001 issue, invention association) can be used suitably.

[Retardation expression agent]
In the present invention, a retardation developing agent is preferably used in order to express a preferable retardation value, and examples of the retardation developing agent that can be used include those composed of rod-like or discotic compounds.
As the rod-like or discotic compound, a compound having at least two aromatic rings can be used.
The addition amount of the retardation developer composed of a rod-shaped compound is preferably 0.1 to 30 parts by mass, and preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the polymer component containing cellulose acylate. Further preferred.

The discotic retardation enhancer is preferably used in a range of 0.05 to 20 parts by mass, and in a range of 0.1 to 10 parts by mass with respect to 100 parts by mass of the polymer component containing the cellulose acylate. It is more preferable to use it, it is more preferable to use it in the range of 0.2 to 5 parts by mass, and it is most preferable to use it in the range of 0.5 to 2 parts by mass.
Since the discotic compound is superior to the rod-like compound in Rth retardation expression, it is preferably used when a particularly large Rth retardation is required.
In the present invention, two or more retardation developing agents may be used in combination.
The retardation developer composed of a rod-like or discotic compound preferably has maximum absorption in the wavelength region of 250 to 400 nm, and preferably has substantially no absorption in the visible region.

The discotic compound will be described. As the discotic compound, a compound having at least two aromatic rings can be used.
In the present specification, the “aromatic ring” includes an aromatic hetero ring in addition to an aromatic hydrocarbon ring.
The aromatic hydrocarbon ring is particularly preferably a 6-membered ring (that is, a benzene ring).
The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of aromatic heterocycles include furan ring, thiophene ring, pyrrole ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, pyrazole ring, furazane ring, triazole ring, pyran ring, pyridine ring , Pyridazine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring.
As the aromatic ring, benzene ring, furan ring, thiophene ring, pyrrole ring, oxazole ring, thiazole ring, imidazole ring, triazole ring, pyridine ring, pyrimidine ring, pyrazine ring and 1,3,5-triazine ring are preferable, In particular, a 1,3,5-triazine ring is preferably used. Specifically, for example, a compound disclosed in JP 2001-166144 A is preferably used as the discotic compound.

The number of aromatic rings contained in the discotic compound is preferably 2 to 20, more preferably 2 to 12, further preferably 2 to 8, and most preferably 2 to 6. preferable.
The bond relationship between two aromatic rings can be classified into (a) a condensed ring, (b) a direct bond with a single bond, and (c) a bond through a linking group (for aromatic rings). , Spiro bonds cannot be formed). The connection relationship may be any of (a) to (c).

  Examples of the condensed ring (a condensed ring of two or more aromatic rings) include an indene ring, a naphthalene ring, an azulene ring, a fluorene ring, a phenanthrene ring, an anthracene ring, an acenaphthylene ring, a biphenylene ring, a naphthacene ring, Pyrene ring, indole ring, isoindole ring, benzofuran ring, benzothiophene ring, indolizine ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring, purine ring, indazole ring, chromene ring, quinoline ring, isoquinoline Ring, quinolidine ring, quinazoline ring, cinnoline ring, quinoxaline ring, phthalazine ring, pteridine ring, carbazole ring, acridine ring, phenanthridine ring, xanthene ring, phenazine ring, phenothiazine ring, phenoxathiin ring, phenoxazine ring and thiant It includes emissions ring. Naphthalene ring, azulene ring, indole ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring and quinoline ring are preferred.

  The single bond (b) is preferably a bond between carbon atoms of two aromatic rings. Two aromatic rings may be bonded with two or more single bonds to form an aliphatic ring or a non-aromatic heterocyclic ring between the two aromatic rings.

The linking group in (c) is also preferably bonded to carbon atoms of two aromatic rings. The linking group is preferably an alkylene group, an alkenylene group, an alkynylene group, —CO—, —O—, —NH—, —S—, or a combination thereof. Examples of linking groups composed of combinations are shown below. In addition, the relationship between the left and right in the following examples of the linking group may be reversed.
c1: -CO-O-
c2: —CO—NH—
c3: -alkylene-O-
c4: —NH—CO—NH—
c5: —NH—CO—O—
c6: —O—CO—O—
c7: -O-alkylene-O-
c8: -CO-alkenylene-
c9: -CO-alkenylene-NH-
c10: -CO-alkenylene-O-
c11: -alkylene-CO-O-alkylene-O-CO-alkylene-
c12: -O-alkylene-CO-O-alkylene-O-CO-alkylene-O-
c13: -O-CO-alkylene-CO-O-
c14: -NH-CO-alkenylene-
c15: -O-CO-alkenylene-

The aromatic ring and the linking group may have a substituent.
Examples of substituents include halogen atoms (F, Cl, Br, I), hydroxyl groups, carboxyl groups, cyano groups, amino groups, nitro groups, sulfo groups, carbamoyl groups, sulfamoyl groups, ureido groups, alkyl groups, alkenyls. Group, alkynyl group, aliphatic acyl group, aliphatic acyloxy group, alkoxy group, alkoxycarbonyl group, alkoxycarbonylamino group, alkylthio group, alkylsulfonyl group, aliphatic amide group, aliphatic sulfonamido group, aliphatic substituted amino group An aliphatic substituted carbamoyl group, an aliphatic substituted sulfamoyl group, an aliphatic substituted ureido group, and a non-aromatic heterocyclic group.

It is preferable that the alkyl group has 1 to 8 carbon atoms. A chain alkyl group is preferable to a cyclic alkyl group, and a linear alkyl group is particularly preferable. The alkyl group may further have a substituent (eg, hydroxy group, carboxy group, alkoxy group, alkyl-substituted amino group). Examples of alkyl groups (including substituted alkyl groups) include methyl, ethyl, n-butyl, n-hexyl, 2-hydroxyethyl, 4-carboxybutyl, 2-methoxyethyl, and 2- A diethylaminoethyl group is included.
The alkenyl group preferably has 2 to 8 carbon atoms. A chain alkenyl group is preferable to a cyclic alkenyl group, and a linear alkenyl group is particularly preferable. The alkenyl group may further have a substituent. Examples of the alkenyl group include a vinyl group, an allyl group, and a 1-hexenyl group.
The alkynyl group preferably has 2 to 8 carbon atoms. A chain alkynyl group is preferable to a cyclic alkynyl group, and a linear alkynyl group is particularly preferable. The alkynyl group may further have a substituent. Examples of the alkynyl group include ethynyl group, 1-butynyl group and 1-hexynyl group.

The number of carbon atoms in the aliphatic acyl group is preferably 1-10. Examples of the aliphatic acyl group include an acetyl group, a propanoyl group, and a butanoyl group.
The number of carbon atoms in the aliphatic acyloxy group is preferably 1-10. Examples of the aliphatic acyloxy group include an acetoxy group.
The number of carbon atoms of the alkoxy group is preferably 1-8. The alkoxy group may further have a substituent (eg, alkoxy group). Examples of the alkoxy group (including a substituted alkoxy group) include a methoxy group, an ethoxy group, a butoxy group, and a methoxyethoxy group.
The number of carbon atoms of the alkoxycarbonyl group is preferably 2-10. Examples of the alkoxycarbonyl group include a methoxycarbonyl group and an ethoxycarbonyl group.
The number of carbon atoms of the alkoxycarbonylamino group is preferably 2-10. Examples of the alkoxycarbonylamino group include a methoxycarbonylamino group and an ethoxycarbonylamino group.

The alkylthio group preferably has 1 to 12 carbon atoms. Examples of the alkylthio group include a methylthio group, an ethylthio group, and an octylthio group.
The alkylsulfonyl group preferably has 1 to 8 carbon atoms. Examples of the alkylsulfonyl group include a methanesulfonyl group and an ethanesulfonyl group.
The number of carbon atoms in the aliphatic amide group is preferably 1-10. Examples of the aliphatic amide group include an acetamide group.
The number of carbon atoms of the aliphatic sulfonamide group is preferably 1-8. Examples of the aliphatic sulfonamido group include a methanesulfonamido group, a butanesulfonamido group, and an n-octanesulfonamido group.
The number of carbon atoms of the aliphatic substituted amino group is preferably 1-10. Examples of the aliphatic substituted amino group include a dimethylamino group, a diethylamino group, and a 2-carboxyethylamino group.
The number of carbon atoms in the aliphatic substituted carbamoyl group is preferably 2-10. Examples of the aliphatic substituted carbamoyl group include a methylcarbamoyl group and a diethylcarbamoyl group.
The number of carbon atoms in the aliphatic substituted sulfamoyl group is preferably 1-8. Examples of the aliphatic substituted sulfamoyl group include a methylsulfamoyl group and a diethylsulfamoyl group.
The number of carbon atoms in the aliphatic substituted ureido group is preferably 2-10. Examples of the aliphatic substituted ureido group include a methylureido group.
Examples of the non-aromatic heterocyclic group include a piperidino group and a morpholino group.
The molecular weight of the retardation developer composed of a discotic compound is preferably 300 to 800.

  The rod-like compound will be described. As the rod-like compound, a compound having a linear molecular structure can be used. The linear molecular structure means that the molecular structure of the rod-like compound is linear in the most thermodynamically stable structure. The most thermodynamically stable structure can be obtained by crystal structure analysis or molecular orbital calculation. For example, molecular orbital calculation can be performed using molecular orbital calculation software (eg, WinMOPAC2000, manufactured by Fujitsu Limited) to obtain a molecular structure that minimizes the heat of formation of a compound. The molecular structure being linear means that in the thermodynamically most stable structure obtained by calculation as described above, the angle of the main chain constituting the molecular structure is 140 degrees or more.

As the rod-shaped compound, those having at least two aromatic rings are preferable, and as the rod-shaped compound having at least two aromatic rings, a compound represented by the following general formula (1) is preferable.
Formula (1): Ar ¹ -L ¹ -Ar ²
In the general formula (1), Ar ¹ and Ar ² are each independently an aromatic group.
In the present specification, the aromatic group includes an aryl group (aromatic hydrocarbon group), a substituted aryl group, an aromatic heterocyclic group, and a substituted aromatic heterocyclic group.
An aryl group and a substituted aryl group are more preferable than an aromatic heterocyclic group and a substituted aromatic heterocyclic group. The heterocycle of the aromatic heterocyclic group is generally unsaturated. The aromatic heterocycle is preferably a 5-membered ring, 6-membered ring or 7-membered ring, more preferably a 5-membered ring or 6-membered ring. Aromatic heterocycles generally have the most double bonds. As a hetero atom, a nitrogen atom, an oxygen atom or a sulfur atom is preferable, and a nitrogen atom or a sulfur atom is more preferable.
As the aromatic ring of the aromatic group, a benzene ring, a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, a thiazole ring, an imidazole ring, a triazole ring, a pyridine ring, a pyrimidine ring and a pyrazine ring are preferable, and a benzene ring is particularly preferable. .

  Examples of the substituent of the substituted aryl group and the substituted aromatic heterocyclic group include a halogen atom (F, Cl, Br, I), a hydroxyl group, a carboxyl group, a cyano group, an amino group, an alkylamino group (eg, methyl). Amino group, ethylamino group, butylamino group, dimethylamino group), nitro group, sulfo group, carbamoyl group, alkylcarbamoyl group (eg, N-methylcarbamoyl group, N-ethylcarbamoyl group, N, N-dimethylcarbamoyl group) ), Sulfamoyl group, alkylsulfamoyl group (eg, N-methylsulfamoyl group, N-ethylsulfamoyl group, N, N-dimethylsulfamoyl group), ureido group, alkylureido group (eg, N -Methylureido group, N, N-dimethylureido group, N, N, N'-trimethylureido group), alkyl group (eg, Methyl, ethyl, propyl, butyl, pentyl, heptyl, octyl, isopropyl, s-butyl, t-amyl, cyclohexyl, cyclopentyl), alkenyl (eg, vinyl, allyl) Group, hexenyl group), alkynyl group (eg, ethynyl group, butynyl group), acyl group (eg, formyl group, acetyl group, butanoyl group, hexanoyl group, lauryl group), acyloxy group (eg, acetoxy group, butanoyloxy) Group, hexanoyloxy group, lauryloxy group), alkoxy group (eg, methoxy group, ethoxy group, propoxy group, butoxy group, pentyloxy group, heptyloxy group, octyloxy group), aryloxy group (eg, phenoxy group) ), Alkoxycarbonyl group (eg, methoxycarbonyl group, ethoxycarbonyl group) , Propoxycarbonyl group, butoxycarbonyl group, pentyloxycarbonyl group, heptyloxycarbonyl group), aryloxycarbonyl group (eg, phenoxycarbonyl group), alkoxycarbonylamino group (eg, butoxycarbonylamino group, hexyloxycarbonylamino group) , Alkylthio groups (eg, methylthio group, ethylthio group, propylthio group, butylthio group, pentylthio group, heptylthio group, octylthio group), arylthio groups (eg, phenylthio group), alkylsulfonyl groups (eg, methylsulfonyl group, ethylsulfonyl group) , Propylsulfonyl group, butylsulfonyl group, pentylsulfonyl group, heptylsulfonyl group, octylsulfonyl group), amide group (eg, acetamido group, butyramide group, hexylamide) , Lauryl amido group) and a non-aromatic Hajime Tamaki (e.g., morpholyl groups include pyrazinyl group).

Examples of the substituent of the substituted aryl group and the substituted aromatic heterocyclic group include a halogen atom, a cyano group, a carboxyl group, a hydroxyl group, an amino group, an alkyl-substituted amino group, an acyl group, an acyloxy group, an amide group, an alkoxycarbonyl group, Alkoxy groups, alkylthio groups and alkyl groups are preferred.
The alkyl part and alkyl group of the alkylamino group, alkoxycarbonyl group, alkoxy group and alkylthio group may further have a substituent. Examples of the alkyl moiety and the substituent of the alkyl group include halogen atom, hydroxyl group, carboxyl group, cyano group, amino group, alkylamino group, nitro group, sulfo group, carbamoyl group, alkylcarbamoyl group, sulfamoyl group, alkylsulfur group. Famoyl group, ureido group, alkylureido group, alkenyl group, alkynyl group, acyl group, acyloxy group, acylamino group, alkoxy group, aryloxy group, alkoxycarbonyl group, aryloxycarbonyl group, alkoxycarbonylamino group, alkylthio group, An arylthio group, an alkylsulfonyl group, an amide group and a non-aromatic heterocyclic group are included. As the substituent for the alkyl moiety and the alkyl group, a halogen atom, a hydroxyl group, an amino group, an alkylamino group, an acyl group, an acyloxy group, an acylamino group, an alkoxycarbonyl group, and an alkoxy group are preferable.

In the general formula (1), L ¹ is a divalent linking group selected from an alkylene group, an alkenylene group, an alkynylene group, —O—, —CO— and a combination thereof.
The alkylene group may have a cyclic structure. As the cyclic alkylene group, cyclohexylene is preferable, and 1,4-cyclohexylene is particularly preferable. As the chain alkylene group, a linear alkylene group is more preferable than a branched alkylene group.
The alkylene group preferably has 1 to 20 carbon atoms, more preferably 1 to 15, more preferably 1 to 10, still more preferably 1 to 8, and most preferably 1 to 6. It is.

The alkenylene group and alkynylene group preferably have a chain structure rather than a cyclic structure, and more preferably have a linear structure rather than a branched chain structure.
The alkenylene group and the alkynylene group preferably have 2 to 10 carbon atoms, more preferably 2 to 8, more preferably 2 to 6, still more preferably 2 to 4, and most preferably 2. (Vinylene or ethynylene).
The arylene group preferably has 6 to 20 carbon atoms, more preferably 6 to 16, and still more preferably 6 to 12.

In the molecular structure of the general formula (1), the angle formed by Ar ¹ and Ar ² across L ¹ is preferably 140 degrees or more.
As the rod-like compound, a compound represented by the following formula (2) is more preferable.
Formula ^{(2): Ar 1 -L 2} -X-L 3 -Ar 2
In the general formula (2), Ar ¹ and Ar ² are each independently an aromatic group. The definition and examples of the aromatic group are the same as those of Ar ¹ and Ar ^{2 in} the general formula (1).

In the general formula (2), L ² and L ³ are each independently a divalent linking group selected from an alkylene group, —O—, —CO— and a group consisting of a combination thereof.
The alkylene group preferably has a chain structure rather than a cyclic structure, and more preferably has a linear structure rather than a branched chain structure.
The alkylene group preferably has 1 to 10 carbon atoms, more preferably 1 to 8, more preferably 1 to 6, still more preferably 1 to 4, and 1 or 2 (methylene or Most preferred is ethylene).
L ² and L ³ are particularly preferably —O—CO— or —CO—O—.

In the general formula (2), X is a 1,4-cyclohexylene group, a vinylene group or an ethynylene group.
Specific examples of the compound represented by the general formula (1) or (2) are shown below, but the compound represented by the general formula (1) or (2) that can be used in the present invention is limited to these. It is not something.

  Specific examples (1) to (34), (41), and (42) have two asymmetric carbon atoms at the 1-position and the 4-position of the cyclohexane ring. However, since the specific examples (1), (4) to (34), (41), and (42) have a symmetrical meso type molecular structure, there are no optical isomers (optical activity), and geometric isomers (trans Type and cis type). The trans type (1-trans) and cis type (1-cis) of specific example (1) are shown below.

As described above, the rod-like compound preferably has a linear molecular structure. Therefore, the trans type is preferable to the cis type.
Specific examples (2) and (3) have optical isomers (a total of four isomers) in addition to geometric isomers. As for geometric isomers, the trans type is similarly preferable to the cis type. The optical isomer is not particularly superior or inferior, and may be D, L, or a racemate.
In specific examples (43) to (45), the central vinylene bond includes a trans type and a cis type. For the same reason as described above, the trans type is preferable to the cis type.

  Other preferred compounds are shown below.

Two or more rod-shaped compounds whose maximum absorption wavelength (λmax) is shorter than 250 nm in the ultraviolet absorption spectrum of the solution may be used in combination.
The rod-like compound can be synthesized by a method described in the literature. As literature, Mol. Cryst. Liq. Cryst. 53, 229 (1979), 89, 93 (1982), 145, 111 (1987), 170, 43 (1989), J. Am. Chem. Soc. 113, 1349 (1991), 118, 5346 (1996), 92, 1582 (1970), J. Org. Chem. 40, 420 pages (1975), Tetrahedron 48, 16 pages, 3437 pages (1992).

[Matting agent fine particles]
It is preferable to add fine particles as a matting agent to the cellulose acylate film of the present invention. The fine particles used in the present invention 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, silica Mention may be made of magnesium and calcium phosphates. Fine particles containing silicon are preferable from the viewpoint of low turbidity, and silicon dioxide is particularly preferable. The fine particles of silicon dioxide preferably have a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more. Those having an average primary particle size as small as 5 to 16 nm are more preferred because they can reduce the haze of the film. The apparent specific gravity is preferably 90 to 200 g / liter or more, and more preferably 100 to 200 g / liter or more. A larger apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.
When the silicon dioxide fine particles are used, the amount used is preferably 0.01 to 0.3 parts by mass with respect to 100 parts by mass of the polymer component containing cellulose acylate.

These fine particles usually form secondary particles having an average particle diameter of 0.1 to 3.0 μm, and these fine particles are present as aggregates of primary particles in the film, and 0.1 to 0.1 μm on the film surface. An unevenness of 3.0 μm is formed. The secondary average particle diameter is preferably 0.2 μm to 1.5 μm, more preferably 0.4 μm to 1.2 μm, and most preferably 0.6 μm to 1.1 μm. If the secondary average particle diameter is in the above range, the effect of preventing squeaking is sufficiently exhibited and the haze is small.
The primary and secondary particle diameters are determined by observing the particles in the film with a scanning electron microscope and using the diameter of a circle circumscribing the particles as the particle diameter. Also, 200 particles are observed at different locations, and the average value is taken as the average particle diameter.

  As the fine particles of silicon dioxide, for example, commercially available products such as Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above Nippon Aerosil Co., Ltd.) can be used. Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.

  Among these, Aerosil 200V and Aerosil R972V are fine particles of silicon dioxide having a primary average particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more, and the coefficient of friction is maintained while keeping the turbidity of the optical film low. It is particularly preferable because it has a great effect of reducing the effect.

In order to obtain a cellulose acylate film having particles having a small secondary average particle size in the present invention, several methods are conceivable when preparing a fine particle dispersion. For example, a method of preparing a fine particle dispersion in which a solvent and fine particles are stirred and mixed in advance, adding the fine particle dispersion to a small amount of a separately prepared cellulose acylate solution, stirring and dissolving, and further mixing with the main cellulose acylate dope solution There is. This method is a preferable preparation method in that the dispersibility of the silicon dioxide fine particles is good and the silicon dioxide fine particles are more difficult to reaggregate. In addition, a small amount of cellulose ester is added to the solvent, stirred and dissolved, and then the fine particles are added and dispersed with a disperser to make this fine particle additive solution. There is also a way to do it. The present invention is not limited to these methods, but the concentration of silicon dioxide when the silicon dioxide fine particles are mixed and dispersed with a solvent or the like is preferably 5 to 30% by mass, more preferably 10 to 25% by mass, and 15 to 20%. Mass% is most preferred. A higher dispersion concentration is preferable because the liquid turbidity with respect to the added amount is lowered, and haze and aggregates are improved. The addition amount of the matting agent in the final cellulose acylate dope solution is preferably 0.01 to 1.0 g, more preferably 0.03 to 0.3 g, and 0.08 to 0.16 g per 1 m ^2. Most preferred.

  The solvent used is preferably lower alcohols such as methyl alcohol, ethyl alcohol, propyl alcohol, isopropyl alcohol, butyl alcohol and the like. Although it does not specifically limit as solvents other than a lower alcohol, It is preferable to use the solvent used at the time of film forming of a cellulose ester.

Next, the organic solvent in which the cellulose acylate of the present invention is dissolved will be described.
In the present invention, any of a chlorinated solvent containing a chlorinated organic solvent as a main solvent and a non-chlorinated solvent not containing a chlorinated organic solvent can be used as the organic solvent.
[Chlorine solvent]
In preparing the cellulose acylate solution of the present invention, a chlorinated organic solvent is preferably used as the main solvent. In the present invention, the type of the chlorinated organic solvent is not particularly limited as long as the object can be achieved within the range in which cellulose acylate can be dissolved and cast and formed. These chlorinated organic solvents are preferably dichloromethane and chloroform. Particularly preferred is dichloromethane. In addition, there is no particular problem in mixing an organic solvent other than the chlorinated organic solvent. In that case, it is necessary to use at least 50% by mass of dichloromethane in the total amount of the organic solvent. Other organic solvents used in combination with the chlorinated organic solvent in the present invention will be described below. That is, as another preferable organic solvent, a solvent selected from esters, ketones, ethers, alcohols, hydrocarbons and the like having 3 to 12 carbon atoms is preferable. Esters, ketones, ethers and alcohols may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO— and —COO—) can also be used as a solvent. You may have group simultaneously. In the case of a solvent having two or more types of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group. Examples of the esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate. Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, and methylcyclohexanone. Examples of ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole. Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.

The alcohol used in combination with the chlorinated organic solvent may be linear, branched or cyclic, and among them, saturated aliphatic hydrocarbon is preferable. The hydroxyl group of the alcohol may be any of primary to tertiary. Examples of the alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, 2-methyl-2-butanol and cyclohexanol. As the alcohol, fluorine-based alcohol is also used. Examples thereof include 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol and the like. Furthermore, the hydrocarbon may be linear, branched or cyclic. Either aromatic hydrocarbons or aliphatic hydrocarbons can be used. The aliphatic hydrocarbon may be saturated or unsaturated. Examples of hydrocarbons include cyclohexane, hexane, benzene, toluene and xylene.
Examples of combinations of chlorinated organic solvents and other organic solvents include the following compositions, but are not limited thereto.

Dichloromethane / methanol / ethanol / butanol (80/10/5/5, parts by mass),
Dichloromethane / acetone / methanol / propanol (80/10/5/5, parts by mass),
Dichloromethane / methanol / butanol / cyclohexane (80/10/5/5, parts by mass),
Dichloromethane / methyl ethyl ketone / methanol / butanol (80/10/5/5, parts by mass),
Dichloromethane / acetone / methyl ethyl ketone / ethanol / isopropanol (75/8/5/5/7, parts by mass),
Dichloromethane / cyclopentanone / methanol / isopropanol (80/7/5/8, parts by mass),
Dichloromethane / methyl acetate / butanol (80/10/10, parts by mass),
Dichloromethane / cyclohexanone / methanol / hexane (70/20/5/5, parts by mass)
Dichloromethane / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5, parts by mass),
Dichloromethane / 1,3-dioxolane / methanol / ethanol (70/20/5/5, parts by mass),
Dichloromethane / dioxane / acetone / methanol / ethanol (60/20/10/5/5, parts by mass),
Dichloromethane / acetone / cyclopentanone / ethanol / isobutanol / cyclohexane (65/10/10/5/5/5, parts by mass),
Dichloromethane / methyl ethyl ketone / acetone / methanol / ethanol (70/10/10/5/5, parts by mass),
Dichloromethane / acetone / ethyl acetate / ethanol / butanol / hexane (65/10/10/5/5/5, parts by mass),
Dichloromethane / methyl acetoacetate / methanol / ethanol (65/20/10/5, parts by mass),
Dichloromethane / cyclopentanone / ethanol / butanol (65/20/10/5, parts by mass),
And so on.

[Non-chlorine solvents]
Next, a non-chlorine organic solvent that is preferably used in preparing the cellulose acylate solution of the present invention will be described. In the present invention, the non-chlorine organic solvent is not particularly limited as long as the object can be achieved as long as the cellulose acylate can be dissolved, cast, and formed into a film. The non-chlorine organic solvent used in the present invention is preferably a solvent selected from esters, ketones and ethers having 3 to 12 carbon atoms. Esters, ketones and ethers may have a cyclic structure. A compound having two or more functional groups of esters, ketones and ethers (that is, —O—, —CO— and —COO—) can also be used as a main solvent, such as an alcoholic hydroxyl group. It may have a functional group of In the case of the main solvent having two or more kinds of functional groups, the number of carbon atoms may be within the specified range of the compound having any functional group. Examples of esters having 3 to 12 carbon atoms include ethyl formate, propyl formate, pentyl formate, methyl acetate, ethyl acetate and pentyl acetate. Examples of ketones having 3 to 12 carbon atoms include acetone, methyl ethyl ketone, diethyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone and methylcyclohexanone. Examples of ethers having 3 to 12 carbon atoms include diisopropyl ether, dimethoxymethane, dimethoxyethane, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, anisole and phenetole. Examples of the organic solvent having two or more kinds of functional groups include 2-ethoxyethyl acetate, 2-methoxyethanol and 2-butoxyethanol.

  The non-chlorine organic solvent used in the above cellulose acylate is selected from the various viewpoints described above, and is preferably as follows. That is, the non-chlorine solvent is preferably a mixed solvent containing the non-chlorine organic solvent as a main solvent, and is a mixed solvent of three or more different solvents, wherein the first solvent is methyl acetate, ethyl acetate, At least one selected from methyl formate, ethyl formate, acetone, dioxolane, and dioxane, or a mixture thereof; the second solvent is selected from ketones having 4 to 7 carbon atoms or acetoacetate; The solvent is a mixed solvent selected from alcohols or hydrocarbons having 1 to 10 carbon atoms, more preferably alcohols having 1 to 8 carbon atoms. Note that when the first solvent is a mixed liquid of two or more kinds of solvents, the second solvent may be omitted. The first solvent is more preferably methyl acetate, acetone, methyl formate, ethyl formate, or a mixture thereof, and the second solvent is preferably methyl ethyl ketone, cyclopentanone, cyclohexanone, methyl acetyl acetate, or a mixed solvent thereof. It may be.

  The alcohol as the third solvent may be linear, branched or cyclic, and is preferably a saturated aliphatic hydrocarbon. The hydroxyl group of the alcohol may be any of primary to tertiary. Examples of the alcohol include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, t-butanol, 1-pentanol, 2-methyl-2-butanol and cyclohexanol. As the alcohol, fluorine-based alcohol is also used. Examples thereof include 2-fluoroethanol, 2,2,2-trifluoroethanol, 2,2,3,3-tetrafluoro-1-propanol and the like. Furthermore, the hydrocarbon may be linear, branched or cyclic. Either aromatic hydrocarbons or aliphatic hydrocarbons can be used. The aliphatic hydrocarbon may be saturated or unsaturated. Examples of hydrocarbons include cyclohexane, hexane, benzene, toluene and xylene. These alcohols and hydrocarbons as the third solvent may be used alone or in combination of two or more, and are not particularly limited. As the third solvent, preferred specific compounds include alcohol, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, and cyclohexanol, cyclohexane, hexane, Are methanol, ethanol, 1-propanol, 2-propanol, 1-butanol.

  The mixing ratio of the above three types of mixed solvents is 20 to 95% by mass for the first solvent, 2 to 60% by mass for the second solvent, and 2 to 30% by mass for the third solvent in the total amount of the mixed solvent. The first solvent is preferably 30 to 90% by mass, the second solvent is 3 to 50% by mass, and the third alcohol is preferably 3 to 25% by mass. . In particular, it is preferable that the first solvent is 30 to 90% by mass, the second solvent is 3 to 30% by mass, and the third solvent is alcohol and 3 to 15% by mass. The non-chlorine-based organic solvent used in the present invention is described in more detail on pages 12 to 16 of the Japan Society for Invention and Innovation (Publication No. 2001-1745, published on March 15, 2001, Japan Institute of Invention). ing. Preferred combinations of non-chlorine organic solvents of the present invention can include the following, but are not limited thereto.

-Methyl acetate / acetone / methanol / ethanol / butanol (75/10/5/5/5, parts by mass),
-Methyl acetate / acetone / methanol / ethanol / propanol (75/10/5/5/5, parts by mass),
Methyl acetate / acetone / methanol / butanol / cyclohexane (75/10/5/5/5, parts by mass),
Methyl acetate / acetone / ethanol / butanol (81/8/7/4, parts by mass)
-Methyl acetate / acetone / ethanol / butanol (82/10/4/4, parts by mass),
-Methyl acetate / acetone / ethanol / butanol (80/10/4/6, parts by mass),
Methyl acetate / methyl ethyl ketone / methanol / butanol (80/10/5/5, parts by mass),
-Methyl acetate / acetone / methyl ethyl ketone / ethanol / isopropanol (75/8/5/5/7, parts by mass)
・ Methyl acetate / cyclopentanone / methanol / isopropanol (80/7/5/8, part by mass), methyl acetate / acetone / butanol (85/10/5, part by mass),
Methyl acetate / cyclopentanone / acetone / methanol / butanol (60/15/14/5/6, parts by mass),
-Methyl acetate / cyclohexanone / methanol / hexane (70/20/5/5, parts by mass)
Methyl acetate / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5, parts by mass),
Methyl acetate / 1,3-dioxolane / methanol / ethanol (70/20/5/5, parts by mass),
Methyl acetate / dioxane / acetone / methanol / ethanol (60/20/10/5/5, parts by mass),
Methyl acetate / acetone / cyclopentanone / ethanol / isobutanol / cyclohexane (65/10/10/5/5/5, parts by mass),
Methyl formate / methyl ethyl ketone / acetone / methanol / ethanol (50/20/20/5/5, parts by mass),
-Methyl formate / acetone / ethyl acetate / ethanol / butanol / hexane (65/10/10/5/5/5, parts by mass)
Acetone / methyl acetoacetate / methanol / ethanol (65/20/10/5, parts by mass)
Acetone / cyclopentanone / ethanol / butanol (65/20/10/5, parts by mass)
Acetone / 1,3-dioxolane / ethanol / butanol (65/20/10/5, parts by mass)
1,3-dioxolane / cyclohexanone / methyl ethyl ketone / methanol / butanol (55/20/10/5/5/5, parts by mass)
And so on.

Further, a cellulose acylate solution prepared by the following method can also be used.
A method of preparing a cellulose acylate solution with methyl acetate / acetone / ethanol / butanol (81/8/7/4, parts by mass) and adding 2 parts by weight of butanol after filtration and concentration. Methyl acetate / acetone / ethanol / Butanol (84/10/4/2, part by mass) A method for adding a cellulose acylate solution and adding 4 parts by weight of butanol after filtration and concentration. Methyl acetate / acetone / ethanol (84/10/6, In addition to the above non-chlorine organic solvent of the present invention, dichloromethane is added to the dope used in the present invention for the addition of 5 parts by weight of butanol after filtration and concentration. You may make it contain 10 mass% or less of the total amount of organic solvents.

[Cellulose acylate solution properties]
The cellulose acylate solution is preferably a solution obtained by dissolving cellulose acylate in the organic solvent at a concentration of 10 to 30% by mass from the viewpoint of film forming casting suitability, and more preferably 13 to 27% by mass. It is particularly preferably 15 to 25% by mass. The method for carrying out the cellulose acylate at these concentrations may be carried out so that the cellulose acylate has a predetermined concentration at the stage of dissolution, or it is prepared as a low-concentration solution (for example, 9 to 14% by mass) and then concentrated as described later. You may adjust to a predetermined high concentration solution by a process. Furthermore, after preparing a high-concentration cellulose acylate solution in advance, various additives may be added to obtain a predetermined low-concentration cellulose acylate solution, and any method will result in the cellulose acylate solution concentration of the present invention. If implemented, there is no particular problem.

Next, in this invention, it is preferable that the aggregate molecular weight of the cellulose acylate in the diluted solution which made the cellulose acylate solution 0.1-5 mass% with the organic solvent of the same composition is 150,000-15 million. More preferably, the associated molecular weight is 180,000 to 9 million. This associated molecular weight can be determined by a static light scattering method. In that case, it is preferable to dissolve so that the inertial square radius required at the same time is 10 to 200 nm. A more preferable inertial square radius is 20 to 200 nm. Furthermore, it is preferable to dissolve so that the second virial coefficient is −2 × 10 ⁻⁴ to + 4 × 10 ^−4, and more preferably the second virial coefficient is −2 × 10 ⁻⁴ to + 2 × 10 ^−4. It is.

Here, the definition of the associated molecular weight, the inertial square radius and the second virial coefficient in the present invention will be described. These are measured using the static light scattering method according to the following method. Although the measurement is performed in a dilute region for the convenience of the apparatus, these measured values reflect the behavior of the dope in the high concentration region of the present invention.
First, cellulose acylate is dissolved in a solvent used for the dope to prepare 0.1 mass%, 0.2 mass%, 0.3 mass%, and 0.4 mass% solutions. In order to prevent moisture absorption, the cellulose acylate is dried at 120 ° C. for 2 hours and is measured at 25 ° C. and 10% RH. The dissolution method is carried out according to the method employed at the time of dope dissolution (room temperature dissolution method, cooling dissolution method, high temperature dissolution method). Subsequently, the solution and the solvent are filtered through a 0.2 μm Teflon filter. The filtered solution is measured for static light scattering at intervals of 10 degrees from 30 degrees to 140 degrees at 25 ° C. using a light scattering measuring device (DLS-700 manufactured by Otsuka Electronics Co., Ltd.). The obtained data is analyzed by the BERRY plot method. In addition, the refractive index required for this analysis uses the value of the solvent calculated | required with the Abbe refractive system, and the refractive index concentration gradient (dn / dc) uses the differential refractometer (Otsuka Electronics Co., Ltd. DRM-1021). Measure using the solvent and solution used for light scattering measurement.

[Dope preparation]
Next, preparation of a cellulose acylate solution (dope) will be described. The method for dissolving the cellulose acylate is not particularly limited, and may be room temperature, or a cooling dissolution method or a high-temperature dissolution method, or a combination thereof. With respect to these, for example, JP-A-5-163301, JP-A-61-106628, JP-A-58-127737, JP-A-9-95544, JP-A-10-95854, JP-A-10-45950, JP 2000-53784, JP 11-322946, JP 11-322947, JP 2-276830, JP 2000-273239, JP 11-71463, JP 04-259511, Special JP-A 2000-273184, JP-A-11-323017, JP-A-11-302388, etc. describe methods for preparing a cellulose acylate solution.
The above-described method for dissolving cellulose acylate in an organic solvent is applicable to the present invention as long as it is within the scope of the present invention. The details of these methods, particularly for non-chlorinated solvent systems, are described in detail on pages 22 to 25 of the Japan Institute of Invention and Technology (Publication No. 2001-1745, published on March 15, 2001, Japan Institute of Invention). Will be implemented. Further, the cellulose acylate dope solution of the present invention is usually subjected to solution concentration and filtration. Similarly, the technical report of the Japan Society of Invention (Publication No. 2001-1745, published on March 15, 2001, Japan Society of Invention), page 25. Are described in detail. In addition, when it melt | dissolves at high temperature, it is the case where it is more than the boiling point of the organic solvent to be used, and in that case, it uses in a pressurized state.

  It is preferable that the cellulose acylate solution has a viscosity and a dynamic storage elastic modulus within the ranges described below because it is easy to cast. 1 mL of the sample solution is measured with a rheometer (CLS 500) using Steel Cone having a diameter of 4 cm / 2 ° (both manufactured by TA Instruments). Measurement conditions were measured at Oscillation Step / Temperature Ramp by changing the range from 40 ° C to -10 ° C at 2 ° C / min, static non-Newtonian viscosity at 40 ° C n * (Pa · s) and storage at -5 ° C The elastic modulus G ′ (Pa) is obtained. The sample solution is preliminarily kept at the measurement start temperature until the liquid temperature becomes constant, and then the measurement is started. In the present invention, the viscosity at 40 ° C. is 1 to 400 Pa · s, the dynamic storage elastic modulus at 15 ° C. is preferably 500 Pa or more, and more preferably the viscosity at 40 ° C. is 10 to 200 Pa · s. And the dynamic storage elastic modulus in 15 degreeC is 100-1 million. Furthermore, it is preferable that the dynamic storage elastic modulus at a low temperature is large. For example, when the casting support is −5 ° C., the dynamic storage elastic modulus is preferably 10,000 to 1,000,000 Pa at −5 ° C. When the body is at −50 ° C., the dynamic storage elastic modulus at −50 ° C. is preferably 10,000 to 5 million Pa.

  In the present invention, since the above-mentioned specific cellulose acylate is used, it is characterized in that a high concentration dope is obtained, and a cellulose acylate having a high concentration and excellent stability without relying on a means of concentration. A solution is obtained. Furthermore, in order to make it easy to melt | dissolve, after making it melt | dissolve at a low density | concentration, you may concentrate using a concentration means. The concentration method is not particularly limited. For example, the low-concentration solution is guided between the cylindrical body and the rotation trajectory of the outer periphery of the rotating blade rotating in the circumferential direction, and the temperature between the solution and the solution. A method of obtaining a high-concentration solution while evaporating the solvent by giving a difference (for example, JP-A-4-259511), a heated low-concentration solution is blown into the container from the nozzle, and the solution is applied from the nozzle to the inner wall of the container In which the solvent is flash evaporated and the solvent vapor is withdrawn from the container and the concentrated solution is withdrawn from the bottom of the container (eg, US Pat. No. 2,541,012, US Pat. No. 2,858,229, US Pat. No. 4,414,341, US Pat. No. 4,504,355, etc.).

Prior to casting, it is preferable to filter off foreign matters such as undissolved matter, dust, and impurities using a suitable filter medium such as a wire mesh or flannel. For the filtration of the cellulose acylate solution, it is preferable to use a filter having an absolute filtration accuracy of 0.1 to 100 μm, and it is more preferable to use a filter having an absolute filtration accuracy of 0.5 to 25 μm. The thickness of the filter is preferably from 0.1 to 10 mm, and more preferably from 0.2 to 2 mm. In that case, the filtration pressure is 1.6 MPa. The following is preferable, more preferably 1.2 MPa or less, further 1.0 MPa or less, and particularly preferably 0.2 MPa or less. As the filter medium, conventionally known materials such as glass fibers, cellulose fibers, filter paper, fluororesins such as tetrafluoroethylene resin can be preferably used, and ceramics, metals and the like are particularly preferably used. The viscosity of the cellulose acylate solution immediately before film formation may be a range that can be cast at the time of film formation. BR> A is usually adjusted to a range of 10 Pa · s to 2000 Pa · s, preferably 30 Pa · s to 1000 Pa · s is more preferable, and 40 Pa · s to 500 Pa · s is still more preferable. The temperature at this time is not particularly limited as long as it is a temperature at the time of casting, but is preferably −5 to + 70 ° C., more preferably −5 to + 55 ° C.

[Film formation]
The cellulose acylate film of the present invention can be obtained by forming a film using the cellulose acylate solution. As the film forming method and equipment, a solution casting film forming method and a solution casting film forming apparatus conventionally used for producing a cellulose triacetate film are used. The dope (cellulose acylate solution) prepared from the dissolving machine (kettle) is once stored in a storage kettle, and the foam contained in the dope is defoamed for final preparation. The dope is sent from the dope discharge port to the pressure die through a pressure metering gear pump capable of delivering a constant amount of liquid with high accuracy, for example, by the number of rotations, and the dope is run endlessly from the die (slit) of the pressure die. The dry-dried dope film (also referred to as web) is peeled off from the metal support at a peeling point that is uniformly cast on the metal support and substantially rounds the metal support. The both ends of the obtained web are sandwiched between clips, transported by a tenter while keeping the width, dried, then transported by a roll group of a drying device, dried, and wound up to a predetermined length by a winder. The combination of the tenter and the roll group dryer varies depending on the purpose. In the solution casting film forming method used for the functional protective film for electronic displays, in addition to the solution casting film forming apparatus, surface processing on films such as an undercoat layer, an antistatic layer, an antihalation layer, a protective layer, etc. Therefore, a coating device is often added. Although each manufacturing process is described briefly below, it is not limited to these.

  First, when the cellulose acylate solution (dope) prepared is produced by a solvent casting method, a dope is cast on a drum or a band, and a solvent is evaporated to form a film. It is preferable to adjust the concentration of the dope before casting so that the solid content is 5 to 40% by mass. The surface of the drum or band is preferably finished in a mirror state. The dope is preferably cast on a drum or band having a surface temperature of 30 ° C. or lower, and particularly preferably a metal support temperature of −10 to 20 ° C. Further, JP 2000-301555, JP 2000-301558, JP 07-032391, JP 03-193316, JP 05-086212, JP 62-037113, JP 02-276607. The methods described in JP-A Nos. 55-014201, 02-111511, and 02-208650 can be used in the present invention.

[Multilayer casting]
The cellulose acylate solution may be cast as a single layer liquid on a smooth band or drum as a metal support, or a plurality of cellulose acylate liquids of two or more layers may be cast. When casting a plurality of cellulose acylate solutions, produce a film while casting and laminating a solution containing cellulose acylate from a plurality of casting openings provided at intervals in the traveling direction of the metal support. For example, the methods described in JP-A-61-158414, JP-A-1-122419, and JP-A-11-198285 can be applied. A film may also be formed by casting a cellulose acylate solution from two casting ports. For example, Japanese Patent Publication Nos. 60-27562, 61-94724, 61-947245, 61-947245, This can be carried out by the methods described in JP-A Nos. 61-104813, 61-158413, and 6-134933. Further, a cellulose acylate film in which a flow of a high-viscosity cellulose acylate solution described in JP-A-56-162617 is wrapped with a low-viscosity cellulose acylate solution and the high- and low-viscosity cellulose acylate solutions are simultaneously extruded. A casting method may be used. Furthermore, it is also a preferred embodiment that the outer solution described in JP-A-61-94724 and JP-A-61-94725 contains a larger amount of an alcohol component which is a poor solvent than the inner solution. Alternatively, by using two casting ports, peeling the film formed on the metal support by the first casting port, and performing the second casting on the side that was in contact with the metal support surface, A film may be prepared, for example, a method described in Japanese Patent Publication No. 44-20235. The cellulose acylate solutions to be cast may be the same solution or different cellulose acylate solutions, and are not particularly limited. In order to give a function to a plurality of cellulose acylate layers, a cellulose acylate solution corresponding to the function may be extruded from each casting port. Furthermore, the cellulose acylate solution can be cast by simultaneously casting other functional layers (for example, an adhesive layer, a dye layer, an antistatic layer, an antihalation layer, a UV absorbing layer, a polarizing layer).

  In the conventional single-layer liquid, it is necessary to extrude a cellulose acylate solution having a high concentration and a high viscosity in order to obtain a necessary film thickness. In many cases, the problem occurs, such as a failure or flatness. As a solution to this, by casting a plurality of cellulose acylate solutions from a casting port, a highly viscous solution can be extruded onto a metal support at the same time. Not only can it be produced, but also a concentrated cellulose acylate solution can be used to reduce the drying load and increase the film production speed. In the case of co-casting, the inner and outer thicknesses are not particularly limited, but preferably the outer side is preferably 1 to 50% of the total film thickness, more preferably 2 to 30%. Here, in the case of co-casting with three or more layers, the total thickness of the layer in contact with the metal support and the layer in contact with the air side is defined as the outer thickness. In the case of co-casting, a cellulose acylate film having a laminated structure can be produced by co-casting cellulose acylate solutions having different additive concentrations such as the above-mentioned plasticizer, ultraviolet absorber and matting agent. For example, a cellulose acylate film having a structure of skin layer / core layer / skin layer can be produced. For example, the matting agent can be contained in the skin layer in a large amount or only in the skin layer. The plasticizer and the ultraviolet absorber can be contained in the core layer more than the skin layer, and may be contained only in the core layer. In addition, the type of plasticizer and ultraviolet absorber can be changed between the core layer and the skin layer. For example, the skin layer contains at least one of a low-volatile plasticizer and an ultraviolet absorber, and the core layer is plastic. It is also possible to add an excellent plasticizer or an ultraviolet absorber excellent in ultraviolet absorption. Moreover, it is also a preferable aspect to contain a peeling accelerator only in the skin layer on the metal support side. It is also preferable to add more alcohol, which is a poor solvent, to the skin layer than the core layer in order to cool the metal support by the cooling drum method to gel the solution. The Tg of the skin layer and the core layer may be different, and the Tg of the core layer is preferably lower than the Tg of the skin layer. Further, the viscosity of the solution containing cellulose acylate during casting may be different between the skin layer and the core layer, and the viscosity of the skin layer is preferably smaller than the viscosity of the core layer. It may be smaller than the viscosity.

[Casting]
As a solution casting method, a method in which the prepared dope is uniformly extruded from a pressure die onto a metal support, and a method using a doctor blade in which the film thickness of the dope once cast on the metal support is adjusted with a blade. Alternatively, there is a method using a reverse roll coater that adjusts with a reverse rotating roll, but a method using a pressure die is preferable. The pressure die includes a coat hanger type and a T die type, and any of them can be preferably used. In addition to the methods listed here, it can be carried out by various methods for casting a cellulose triacetate solution known in the art, and by setting each condition in consideration of differences in the boiling point of the solvent used, etc. The same effects as described in the above publication can be obtained. The endlessly running metal support used for producing the cellulose acylate film of the present invention includes a drum whose surface is mirror-finished by chrome plating and a stainless steel belt whose surface is mirror-finished by surface polishing (referred to as a band). May be used). One or two or more pressure dies used for producing the cellulose acylate film of the present invention may be installed above the metal support. Preferably 1 or 2 groups. When two or more are installed, the dope amount to be cast may be divided into various ratios for each die, or the dope may be fed to the dies from each of a plurality of precision quantitative gear pumps. The temperature of the cellulose acylate solution used for casting is preferably −10 to 55 ° C., more preferably 25 to 50 ° C. In that case, all of the processes may be the same, or may be different at various points in the process. If they are different, the temperature may be a desired temperature just before casting.

[Dry]
The drying of the dope on the metal support involved in the production of the cellulose acylate film is generally a method of applying hot air from the surface side of the metal support (drum or belt), that is, the surface of the web on the metal support, A method of applying hot air from the back of the drum or belt, contacting the temperature-controlled liquid from the back of the belt or drum opposite the dope casting surface, and heating the drum or belt by heat transfer to control the surface temperature Although there is a heat transfer method, the back surface liquid heat transfer method is preferable. The surface temperature of the metal support before casting may be any number as long as it is not higher than the boiling point of the solvent used for the dope. However, in order to promote drying and to lose fluidity on the metal support, the temperature should be set to 1 to 10 ° C. lower than the boiling point of the lowest boiling solvent used. Is preferred. This is not the case when the casting dope is cooled and peeled off without drying.

[Stretching treatment]
In the cellulose acylate film of the present invention, the retardation can be adjusted by a stretching treatment. Furthermore, there is also a method of positively stretching in the width direction. For example, JP-A-62-115035, JP-A-4-152125, JP-A-4-284111, JP-A-4-298310, and JP-A-11 -48271, and the like. This stretches the produced film in order to increase the in-plane retardation value of the cellulose acylate film.
The film is stretched at room temperature or under heating conditions. The heating temperature is preferably around 10 ° C. across the glass transition temperature of the film. The stretching of the film may be uniaxial stretching only in the longitudinal or lateral direction, or may be simultaneous or sequential biaxial stretching. Stretching is performed at 1 to 200%. The stretching is preferably performed at 1 to 100%, particularly preferably at 1 to 80%. The birefringence of the optical film is preferably such that the refractive index in the width direction is larger than the refractive index in the length direction. Therefore, it is preferable to stretch more in the width direction. In addition, the stretching process may be performed in the middle of the film forming process, or the raw film that has been formed and wound may be stretched. In the former case, stretching may be performed in a state including the residual solvent amount, and the residual solvent amount (residual solvent amount / (residual solvent amount + solid content amount)) may be preferably 2 to 50%.
For the purpose of improving the wavelength dispersion characteristics of retardation in the front and film thickness directions of the film, the stretching of the film is preferably 30 ° C to 100 ° C higher than the glass transition temperature, and 35 ° C to 90 ° C higher. It is more preferable that the temperature is higher by 40 to 80 ° C.
By making the film stretching temperature 30 ° C to 100 ° C higher than the glass transition temperature, the Re wavelength dispersion characteristic is inversely dispersed (Re ₍₄₀₀₎ <Re ₍₇₀₀₎ ), and the Rth wavelength dispersion characteristic is forwardly dispersed. (Rth ₍₄₀₀₎ > Rth ₍₇₀₀₎ ). Therefore, it is possible to improve the viewing angle, contrast, and black color change when mounted on the liquid crystal display device.

(Cyclic polyolefin)
Next, the cyclic polyolefin preferably used in the present invention will be described in detail. In the present invention, two or more different types of cyclic polyolefins may be mixed and used.
The cyclic polyolefin in the present invention has a structure in which a cyclic olefin is polymerized. Examples of cyclic polyolefins include (1) norbornene polymers, (2) monocyclic olefin polymers, (3) cyclic conjugated diene polymers, (4) vinyl alicyclic hydrocarbon polymers, and Examples of the hydride include (1) to (4). As cyclic polyolefin preferably used in the present invention, an addition (co) polymer containing at least one repeating unit represented by the following general formula (II), at least one repeating unit represented by the following general formula (II) And an addition (co) polymer containing at least one repeating unit represented by the following general formula (I), and a ring-opening (co) polymer containing at least one cyclic repeating unit represented by the following general formula (III) Coalescence can be mentioned.

In the above formula, m represents an integer of 0 to 4. R ^{1 to} R ⁶ are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, X ^{1 to} X ³ and Y ^{1 to} Y ³ are each independently a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, A halogen atom, a hydrocarbon group having 1 to 10 carbon atoms substituted with a halogen atom, — (CH ₂ ) _n COOR ¹¹ , — (CH ₂ ) _n OCOR ¹² , — (CH ₂ ) _n NCO, — (CH ₂ ) _{n NO 2, - (CH 2} ) n CN, - (CH 2) n CONR 13 R 14, - (CH 2) n NR 13 R 14, - (CH 2) n OZ , or - with (CH _{2) n} W Or X ¹ and Y ¹ , X ² and Y ^2, or X ³ and Y ³ are bonded to each other to represent —COOCO— or —CONR ¹⁵ CO—. R ^{11 to} R ¹⁵ are each independently a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, Z is a hydrocarbon group or a hydrocarbon group substituted with halogen, and W is SiR ¹⁶ _p D _3-p (R ¹⁶ is a hydrocarbon group having 1 to 10 carbon atoms, D is a halogen atom, —OCOR ¹⁶ or —OR ¹⁶ , p is an integer of 0 to 3), and n is an integer of 0 to 10.

By introducing a highly polarizable functional group into the substituents of X ^{1 to} X ³ and Y ^{1 to} Y ³ , the thickness direction retardation (Rth) of the optical film is increased and the in-plane retardation (Re) of The expression can be increased. A film having a high Re developability can increase the Re value by stretching in the film forming process.

  Norbornene-based addition (co) polymers are disclosed in JP-A-10-7732, JP-T 2002-504184, US Patent Publication No. 2004 / 229157A1 and International Publication No. 2004 / 070463A1. A thing etc. can be used. The norbornene-based addition (co) polymer is obtained by addition polymerization of norbornene-based polycyclic unsaturated compounds. If necessary, norbornene-based polycyclic unsaturated compounds and conjugated dienes such as ethylene, propylene, butene, butadiene and isoprene; non-conjugated dienes such as ethylidene norbornene; acrylonitrile, acrylic acid, methacrylic acid, anhydrous It can also be obtained by addition polymerization with a linear diene compound such as maleic acid, acrylic acid ester, methacrylic acid ester, maleimide, vinyl acetate or vinyl chloride. A commercially available product can also be used as the norbornene-based addition (co) polymer. Specifically, APL8008T (Tg70 ° C), APL6013T (Tg125 ° C), APL6015T (Tg145 ° C), etc. sold by Mitsui Chemicals, Inc. TOPAS8007, TOPAS6013, TOPAS6015, etc. sold by Polyplastics Co., Ltd. Pellets, and Appear 3000 sold by Ferrania.

  Norbornene-based polymer hydrides are disclosed in JP-A-1-240517, JP-A-7-196736, JP-A-60-26024, JP-A-62-19807, JP-A-2003-1159767, or As disclosed in JP-A-2004-309979 and the like, it can be obtained by subjecting a polycyclic unsaturated compound to addition polymerization or metathesis ring-opening polymerization and then hydrogenation.

In general formula (III), R ⁵ and R ⁶ are each independently preferably a hydrogen atom or —CH ₃ , and X ³ and Y ³ are each independently preferably a hydrogen atom, Cl or —COOCH ₃ . As such a preferred norbornene-based resin, a commercially available product can be used, and specifically, Arton G and Arton F, which are sold by JSR Corporation, and Nippon Zeon Corporation. Mention may be made of Zeonor ZF14, ZF16, Zeonex 250 and Zeonex 280.

  The cyclic polyolefin used in the present invention preferably has a mass average molecular weight (Mw) measured by gel permeation chromatography (GPC) of 5,000 to 1,000,000 in terms of polystyrene molecular weight. More preferably, it is -500,000, and it is further more preferable that it is 50,000-300,000. Moreover, it is preferable that molecular weight distribution (Mw / Mn; Mn is the number average molecular weight measured by GPC) is 10 or less, More preferably, it is 5.0 or less, More preferably, it is 3.0 or less. The glass transition temperature (Tg) measured by DSC is preferably 50 to 350 ° C, more preferably 80 to 330 ° C, still more preferably 100 to 300 ° C.

  Regarding the method for producing a film using a cyclic polyolefin, the additive components at that time, and the application of the produced film, the above description regarding cellulose acylate can be referred to.

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

<Examples 1-5, Comparative Examples 1 and 2>
(1) Production of transparent film for protective film (1-1) Production of transparent film sample 101 Acetyl substitution degree is 2.86, substitution degree of acyl group having 3 or more carbon atoms is 0.0, acyl at 6 position 100 parts by mass of cellulose acetate having a substitution degree / total substitution degree of 0.317, 10 parts by mass of triphenyl phosphate (TPP), 400 parts by mass of methylene chloride (first solvent), 60 parts by mass of methanol (second solvent) These were dissolved in each mixing tank and stirred to prepare a cellulose acetate solution. This cellulose acetate solution was filtered, cast onto a metal support, held in a tenter zone at 100 ° C. and conveyed, and then dried by passing through a 130 ° C. drying zone for 30 minutes, whereby a transparent film sample 101 was produced. The resulting transparent film 101 had a residual solvent amount of 0.2% or less and a film thickness of 40 μm.

(1-2) Production of transparent film sample 102 A transparent film having a film thickness of 50 μm was used in the same manner as sample 101 except that the cellulose acetate solution used for production of transparent film sample 101 was used and the film thickness during casting was changed. Sample 102 was prepared.

(1-3) Production of transparent film sample 103 A transparent film having a film thickness of 70 μm was used in the same manner as sample 101 except that the cellulose acetate solution used for production of transparent film sample 101 was used and the film thickness during casting was changed. Sample 103 was produced.

(1-4) Production of transparent film sample 104 A transparent film having a film thickness of 80 μm is used in the same manner as sample 101 except that the cellulose acetate solution used for production of transparent film sample 101 is used and the film thickness during casting is changed. Sample 104 was produced.

(2) Production of Polarizing Plate The transparent film samples 101 to 104 were immersed in a 1.5 mol / L sodium hydroxide aqueous solution at 55 ° C. for 2 minutes. It wash | cleaned in the room temperature water-washing tub, and neutralized using the 0.1 mol / L sulfuric acid at 30 degreeC. Again, it was washed in a water bath at room temperature and further dried with hot air at 100 ° C. Thus, the surface of each transparent film sample was surface-treated.
A roll-shaped polyvinyl alcohol film having a thickness of 80 μm was continuously stretched 5 times in an aqueous iodine solution and dried to obtain a polarizer having a thickness of 25 μm.
Using a polyvinyl alcohol adhesive on both surfaces of a 25 μm-thick polarizer, the surface-treated transparent film samples 101 to 104 are bonded as protective films in the configuration shown in Table 1, and the front side (viewing side) iodine A system polarizing plate was produced. Further, the surface-treated transparent film sample 104 (thickness 80 μm) is bonded to both surfaces of a 25 μm-thick polarizer using a polyvinyl alcohol-based adhesive as a protective film, and the back side (backlight side) iodine-based polarized light. A plate was prepared.

(3) Production of liquid crystal display device An acrylic adhesive is used on the front and back sides of a 26-inch (horizontal long side 58 cm, vertical short side 35 cm) size IPS liquid crystal cell using a 0.5 mm thick glass substrate. A liquid crystal panel was manufactured by bonding so that the polarizing plate and the substrate were in contact with each other in the configuration shown in FIG. 1, and this liquid crystal panel was assembled in a housing to prepare a liquid crystal display device (FIG. 1). It was confirmed in advance that the elastic modulus of the adhesive and pressure-sensitive adhesive used in this case had almost no difference between the long side direction and the short side direction, and the value of the elastic modulus was negligible with respect to other members. .

  When manufacturing each liquid crystal display device, the polarizer absorption axis of the polarizing plate constituting the front side laminate, the machine transport direction of the protective film constituting the front side laminate, and the long side direction of the panel are parallel, The polarizer absorption axis of the polarizing plate constituting the back-side laminate and the mechanical transport direction of the protective film constituting the back-side laminate are parallel, and the polarizing axis constituting the absorption axis of the polarizing plate constituting the front-side laminate and the back-side laminate Each member was arrange | positioned so that the absorption axis of a board might orthogonally cross.

(4) Evaluation by wet heat treatment of liquid crystal display device The prepared liquid crystal display device was left for 50 hours in an environment of a temperature of 50 ° C. and a relative humidity of 95%. After the treatment, it was transferred to an environment at a temperature of 25 ° C. and a relative humidity of 60%. The power was turned on, and the black display state was visually observed. Next, only the panel was taken out from the liquid crystal display device, and the amount of warpage w at the time when 20 minutes had elapsed after moving to an environment of temperature 25 ° C. and relative humidity 60% was measured. The warpage rate w / L (mm / mm) was determined by dividing the warpage amount w by the length L in the long side direction, and the results are shown in Table 1.

<Examples 6 to 10, Comparative Examples 3 and 4>
(1) Preparation of cellulose acylate The degree of acetyl substitution (A) is 1.9 and the degree of substitution of acyl groups having 3 or more carbon atoms is 0.8 (all acyl groups having 3 or more carbon atoms are propionyl groups. , B is equal to the propionyl substitution degree], a cellulose acylate having an acyl substitution degree at the 6-position of 0.897 and an acyl substitution degree at the 6-position / total substitution degree of 0.332 was prepared. That is, sulfuric acid (7.8 parts by mass with respect to 100 parts by mass of cellulose) was added to cellulose as a catalyst, carboxylic acid serving as a raw material for the acyl substituent was added, and an acylation reaction was performed at 40 ° C. At this time, the kind of acyl group to be substituted, the total substitution degree, and the 6-position substitution degree were adjusted by adjusting the amount of sulfuric acid catalyst, the amount of water, and the aging time. The aging temperature was 40 ° C. Moreover, it age | cure | ripened at 40 degreeC after acylation. Further, the low molecular weight component of the cellulose acylate was removed by washing with acetone.

(2) Dope preparation (2-1) Cellulose acylate solution The following composition is put into a mixing tank, stirred to dissolve each component, heated to 90 ° C. for about 10 minutes, and then filtered with an average pore size of 34 μm. And it filtered with the sintered metal filter with an average hole diameter of 10 micrometers.

(Composition of cellulose acylate solution)
Cellulose acylate prepared in (1) 100.0 parts by mass Triphenyl phosphate 8.0 parts by mass Biphenyl diphenyl phosphate 4.0 parts by mass Methylene chloride 403.0 parts by mass Methanol 60.2 parts by mass

(2-2) Matting Agent Dispersion Next, the following composition containing the cellulose acylate solution prepared by the above method was charged into a disperser to prepare a matting agent dispersion.

(Composition of matting agent dispersion)
Silica particles (average particle size 16 nm) 2.0 parts by mass
"aerosil R972" {Nippon Aerosil Co., Ltd.}
Methylene chloride 72.4 parts by mass Methanol 10.8 parts by mass The above cellulose acylate solution 10.3 parts by mass

(2-3) Retardation developer solution A
Next, the following composition containing the cellulose acylate solution produced by the above method was put into a mixing tank and dissolved by stirring while heating to prepare a retardation developer solution A.

(Composition of retardation developer solution A)
Retardation developer (RP1 having the following structure) 20.0 parts by mass Methylene chloride 58.3 parts by mass Methanol 8.7 parts by mass The above cellulose acylate solution 12.8 parts by mass

  100 parts by mass of the cellulose acylate solution, 1.35 parts by mass of the matting agent dispersion, and 3 parts by mass of the retardation developer solution A were mixed to prepare a dope for film formation. This dope was used for film production. The retardation developer solution A is a mass part of the retardation developer when the cellulose acylate amount is 100 parts by mass.

(3) Production of transparent film for protective film The dope was cast using a band casting machine. A film peeled off from the band with a residual solvent amount of 25 to 35% by mass was controlled by adjusting the stretching temperature within a range from a temperature about 5 ° C. lower to a temperature about 5 ° C. higher than the glass transition temperature of the cellulose acylate film. A cellulose acylate film having a thickness of 40 μm was formed by stretching in the machine direction and the width direction using a tenter. This was designated as a transparent film sample 201.
By changing the film thickness at the time of casting and performing the same procedure, a transparent film sample 202 with a film thickness of 50 μm, a transparent film sample 203 with a film thickness of 70 μm, and a transparent film sample 204 with a film thickness of 80 μm were produced.

(4) Production of polarizing plate and liquid crystal display device Using the transparent film samples 201 to 204 as described in Table 2, a polarizing plate was prepared in the same manner as in Examples 1 to 5, and further a liquid crystal display A device was made.

(5) Evaluation by wet heat treatment of liquid crystal display device For the prepared liquid crystal display device, the warpage rate w / L (mm / mm) was obtained using the same method as in Examples 1 to 5, and the results are shown in Table 2. did.

<Examples 11 to 15 and Comparative Examples 5 and 6>
(1) Preparation of cellulose acylate Degree of acetyl substitution (A) is 1.4, substitution degree of acyl group having 3 or more carbon atoms (B) is 1.3 [all acyl groups having 3 or more carbon atoms are butanoyl groups , B is equal to the butanoyl substitution degree], and a cellulose acylate having an acyl substitution degree at the 6-position of 0.880 and an acyl substitution degree at the 6-position / total substitution degree of 0.326 was prepared. That is, sulfuric acid (7.8 parts by mass with respect to 100 parts by mass of cellulose) was added to cellulose as a catalyst, carboxylic acid serving as a raw material for acyl substituents was added, and an acylation reaction was performed at 40 ° C. At this time, by adjusting the amount of sulfuric acid catalyst, the amount of water, and the aging time, the kind of acyl group to be substituted, the total substitution degree, and the 6-position substitution degree were adjusted. The aging temperature was 40 ° C. Moreover, it age | cure | ripened at 40 degreeC after acylation. Further, the low molecular weight component of the cellulose acylate was removed by washing with acetone.

(2) Dope preparation (2-1) Cellulose acylate solution The following composition is put into a mixing tank, stirred to dissolve each component, heated to 90 ° C. for about 10 minutes, and then filtered with an average pore size of 34 μm. And it filtered with the sintered metal filter with an average hole diameter of 10 micrometers.

(Composition of cellulose acylate solution)
Cellulose acylate prepared in (1) 100.0 parts by mass Triphenyl phosphate 8.0 parts by mass Biphenyl diphenyl phosphate 4.0 parts by mass Methylene chloride 403.0 parts by mass Methanol 60.2 parts by mass

(2-2) Matting Agent Dispersion Next, the following composition containing the cellulose acylate solution prepared by the above method was charged into a disperser to prepare a matting agent dispersion.

(Composition of matting agent dispersion)
Silica particles (average particle size 16 nm) 2.0 parts by mass
"aerosil R972" {Nippon Aerosil Co., Ltd.}
Methylene chloride 72.4 parts by mass Methanol 10.8 parts by mass The above cellulose acylate solution 10.3 parts by mass

(2-3) Retardation developer solution A
Next, the following composition containing the cellulose acylate solution produced by the above method was put into a mixing tank and dissolved by stirring while heating to prepare a retardation developer solution A.

(Composition of retardation developer solution A)
Retardation developer (RP1) 20.0 parts by mass Methylene chloride 58.3 parts by mass Methanol 8.7 parts by mass The above cellulose acylate solution 12.8 parts by mass

  100 parts by mass of the cellulose acylate solution, 1.35 parts by mass of the matting agent dispersion, and 3 parts by mass of the retardation developer solution A were mixed to prepare a dope for film formation. This dope was used for film production. The retardation developer solution A is a mass part of the retardation developer when the cellulose acylate amount is 100 parts by mass.

(3) Production of transparent film for protective film The dope was cast using a band casting machine. A film peeled off from the band with a residual solvent amount of 25 to 35% by mass was controlled by adjusting the stretching temperature within a range from a temperature about 5 ° C. lower to a temperature about 5 ° C. higher than the glass transition temperature of the cellulose acylate film. A cellulose acylate film having a thickness of 40 μm was formed by stretching in the machine direction and the width direction using a tenter. This was designated as a transparent film sample 301.
By changing the film thickness at the time of casting and performing the same procedure, a transparent film sample 302 having a thickness of 50 μm, a transparent film sample 303 having a thickness of 70 μm, and a transparent film sample 304 having a thickness of 80 μm were produced.

(4) Preparation of polarizing plate and liquid crystal display device Using the transparent film samples 301 to 304 as described in Table 3, a polarizing plate was prepared in the same manner as in Examples 1 to 5, and further a liquid crystal display A device was made.

(5) Evaluation by wet heat treatment of liquid crystal display device For the prepared liquid crystal display device, the warpage rate w / L (mm / mm) was obtained using the same method as in Examples 1 to 5, and the results are shown in Table 3. did.

<Example 16>
Nippon Zeon Co., Ltd. cycloolefin polymer film sample 401 {Zeonor film, film thickness 100 μm}, sample 402 {Zeonor film, film thickness 84 μm}, sample 403 {Zeonor film, film thickness 70 μm} Then, this corona-treated surface side was adhered to one surface of a polarizer produced in the same manner as in Examples 1 to 5 using a polyvinyl alcohol-based adhesive. In addition, cellulose acetate film samples 101, 102, 103, and 104 (substrate-side protective films) whose surfaces were saponified in the same manner as in Examples 1 to 5 were bonded to the other surface of the polarizer using the same adhesive. Then, the viewing-side polarizing plate (front-side laminate) described in Table 4 was produced. A liquid crystal display device was prepared and evaluated in the same manner as in Example 1 using the viewing side polarizing plate. The results are shown in Table 4.

<Example 25>
Nippon Zeon Co., Ltd. cycloolefin polymer film sample 401 {Zeonor film, film thickness 100 μm} was corona-treated, and this corona-treated surface side was visually recognized on one surface of a polarizer produced in the same manner as in Example 1. The side protective film was bonded using a polyvinyl alcohol-based adhesive. Further, a cellulose acetate film sample 104 {film thickness 80 μm} (substrate-side protective film) whose surface was saponified in the same manner as in Example 1 was bonded to the other surface of the polarizer using the same adhesive. Furthermore, a cycloolefin polymer film {ZEONOR film, film thickness 84 µm} made by Nippon Zeon Co., Ltd. is bonded to the cycloolefin polymer film side of this laminate through an adhesive sheet {SK-1478 made by Soken Chemical Co., Ltd.}. (Back side laminate) was produced. A liquid crystal display device was prepared and evaluated in the same manner as in Example 16 except that the above-mentioned back side polarizing plate was used. As a result, the warpage rate w / L (mm / mm) was 0.0001.

  As is clear from Tables 1 to 4, the liquid crystal display devices of Examples 1 to 25 manufactured using a protective film having a predetermined thickness and having a predetermined arrangement have less warping of the panel, and display deterioration due to the warpage is deteriorated. It was not seen and it was confirmed that it was a level with no problem in practical use. On the other hand, in the liquid crystal display device of the comparative example, the panel warpage rate is as high as 0.006 or more, corner unevenness due to warpage occurs, light leaks at the four corners, and there is a problem in practical use. It was confirmed that.

  In the image display device of the present invention, since the warpage of the panel is suppressed, it is possible to effectively suppress a decrease in display performance. For this reason, it is possible to maintain excellent display performance even under conditions in which environmental changes are significant. Therefore, the present invention has high industrial applicability.

It is sectional drawing which shows the structural example of the image display apparatus of this invention (an upper side is a visual recognition side).

Explanation of symbols

(A) Front side laminate (B) Substrate (C) Back side laminate (D) Housing

Claims (15)

  A polarizing plate in which at least one protective film is provided on each side of the polarizer, and the total thickness of the protective film provided on one side of the polarizer is the total of the protective films provided on the opposite side of the polarizer. A polarizing plate characterized by being 10 μm or more thinner than the thickness.   A polarizing plate in which one protective film is provided on one side of the polarizer and at least one protective film is provided on the opposite side of the polarizer, and one protective film is provided on one side of the polarizer A polarizing plate, wherein the thickness of the film is 10 μm or more thinner than the total thickness of the protective film provided on the opposite side of the polarizer.   The polarizing plate according to claim 1 or 2, wherein at least one of the protective films constituting the polarizing plate is made of cellulose acylate. The cellulose acylate has a structure in which a hydroxyl group of a glucose unit constituting cellulose is substituted with an acyl group having 2 or more carbon atoms, and satisfies the following formulas (1) and (2): The polarizing plate according to claim 3.
Formula (1): 2.0 ≦ DS ₂ + DS ₃ + DS ₆ ≦ 3.0
Formula (2): DS ₆ / (DS ₂ + DS ₃ + DS ₆ ) ≧ 0.315
[In the formula, DS ₂ represents the substitution degree of the hydroxyl group at the 2-position of the glucose unit constituting the cellulose with an acyl group, DS ₃ represents the substitution degree of the hydroxyl group at the 3-position with an acyl group, and DS ₆ represents the hydroxyl group at the 6-position. Represents the degree of substitution with an acyl group. ]   The polarizing plate according to claim 4, wherein the acyl group is an acetyl group. The protective film made of cellulose acylate has a mixed polymer ester of cellulose as a main polymer component,
The mixed fatty acid ester of cellulose has a structure in which a hydroxyl group of cellulose is substituted with an acetyl group and an acyl group having 3 or more carbon atoms, and satisfies the following formulas (3) and (4): The polarizing plate according to claim 3.
Formula (3): 2.0 ≦ A + B ≦ 3.0
Formula (4): 0 <B
[In the formula, A represents the substitution degree of the acetyl group of cellulose acylate, and B represents the substitution degree of the acyl group having 3 or more carbon atoms. ]   The polarizing plate according to claim 6, wherein the acyl group having 3 or more carbon atoms is a propionyl group or a butanoyl group.   The polarizing plate according to claim 6 or 7, wherein the substitution degree of the hydroxyl group at the 6-position of cellulose in the cellulose acylate is 0.75 or more.   The polarizing plate according to claim 1 or 2, wherein at least one of the protective films constituting the polarizing plate comprises a cyclic polyolefin.   The total thickness of the protective film on one side of the polarizer is 30 μm to 50 μm, and the total thickness of the protective film on the opposite side of the polarizer is 70 μm to 150 μm. The polarizing plate as described in a term. An image display device comprising a substrate made of glass or resin, a front side laminate provided on the viewing side of the substrate, and a panel having a back side laminate provided on the opposite side of the substrate,
The said front side laminated body was installed so that the total thickness of the protective film provided in the board | substrate side of a polarizer might be 10 micrometers or more thinner than the total thickness of the protective film provided in the visual recognition side of a polarizer. An image display device, which is the polarizing plate according to claim 10.   The image display device according to claim 11, wherein the panel is rectangular or square and one side is 10 cm to 500 cm.   The image display device according to claim 11 or 12, wherein a front surface of the panel is open, and a back surface of the panel is closed by a casing.   The image display device according to claim 11, wherein the substrate has a liquid crystal cell, and the back-side laminate has an optical compensation film.   The image display device according to claim 11, wherein a VA mode or IPS mode liquid crystal display mode is used.

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