JP5547882B2 - Film, film manufacturing method, polarizing plate, optical compensation film, antireflection film, and liquid crystal display device - Google Patents

Description

  The present invention relates to a method for producing a film. The present invention also relates to a film produced by the production method, a polarizing plate having the film, and a liquid crystal display device.

  In recent years, with the rise of the liquid crystal display market, various films have been developed. For example, Patent Documents 1 to 3 disclose inclined retardation films.

For example, Patent Document 1 discloses that a film is passed between two rolls having different peripheral speeds, thereby applying a shearing force to the film to create a film with an inclined optical axis, and a TN type liquid crystal display. Applications are described. However, the method of this patent has problems such as large variations in optical properties of the film and easy contact scratches on the film surface. Nor did it suggest application to melts. Therefore, Patent Documents 2 and 3 describe that the above problem can be solved by sandwiching the melt using two rolls of a metal roll that may be different in peripheral speed from a rubber roll and applying a shearing force. .
However, the effect of optical compensation is not sufficient simply by using an optical film having an inclined optical axis for a liquid crystal display. For example, Patent Document 3 discloses an optical film in which the optical axis is inclined by 11.5 to 18.2 ° in the embodiment, but there is no description about the relationship between the optical axis inclination angle and the optical compensation of the liquid crystal display. Actually, in order to perform optical compensation of a transmissive TN or ECB liquid crystal display or a transflective ECB liquid crystal display, the tilt structure has a large phase difference until the retardation of the liquid crystal cell can be compensated. A large optical film has been desired. Furthermore, an optical film with high uniformity of optical properties has been desired.

  Conventionally, it is known that when the roll pressure is increased, a film in which a large compressive force acts in the thickness direction and molecular chains are selectively oriented in the thickness direction can be produced. However, in Patent Document 4, a film in which a large residual strain is generated by increasing the roll pressure causes irregular reflection of light and birefringence phenomenon. Therefore, it cannot be used for optical applications or liquid crystal display devices, and the film thickness is about 300 μm. The limit is disclosed. For this reason, it is disclosed that it is preferable to reduce the roll pressure to reduce the phase difference in optical applications. In fact, it is known that the film produced by the melt touch roll method is more oriented in the thickness direction than the film produced by the melt cast method.

On the other hand, a film produced by a melt film forming method generally has a thick film end due to a neck-in phenomenon. Therefore, it is known that the touch roll first hits the end of the film, and it is difficult to apply sufficient pressure uniformly to the center of the film. In addition, when the pressing pressure of the roll is increased, there is a problem that although the pressure at the film end increases, the pressure at the center of the film hardly increases. On the other hand, using a roll having a roll width shorter than the film width, a method of manufacturing a thermoplastic film by passing a film-like melt of a thermoplastic resin between two constant speed rolls is known (patent) Reference 5). This document discloses that by using a roll having a roll width shorter than the film width, the residual phase difference of the film can be reduced and the optical axis variation can be reduced. However, none of Patent Documents 1 to 5 describes a method for producing a film that further increases the residual retardation. That is, a method for producing a film suitable for optical applications having a large inclined structure and high optical property uniformity has not been known.
JP-A-6-222213 JP 2003-25414 A JP 2007-38646 A Japanese Patent No. 3194904 JP 2005-172940 A

  In the conventional optical film field, when the pressure between the rolls is increased, the compressive force increases, so the molecular chains are selectively oriented in the thickness direction, and even if the shearing force (slip) applied to the melt increases, the phase difference does not occur. It was expected that the size of the inclined structure would decrease relatively. However, in the manufacturing method in which the inventor creates a film having a tilted phase difference structure using two rolls having different peripheral speeds, the pressure between the two rolls is increased and the pressure is uniformly applied in the film width direction. Upon examination, it was surprisingly found that a film having a large inclined structure and high optical property uniformity can be produced. That is, it was impossible to predict that a film having a large inclined structure and high optical property uniformity can be produced by increasing the roll pressure in this way.

  The present invention has been made in consideration of the above-mentioned problems, and a first object of the present invention is to provide a film having a large tilted phase difference structure and high uniformity of optical characteristics and a method for producing the same. . The second object of the present invention is to provide a polarizing plate, an optical compensation film, an antireflection film and a liquid crystal display device using the film.

  As a result of intensive studies to solve the above problems, the present inventors have made a film that passes between two rolls by preventing a portion of 50 to 500 mm from the film end from contacting at least one of the two rolls. The present invention described below has been completed by finding that the film can be formed by applying a high pressure of 5 MPa or more uniformly in the width direction of the melt, and the above problems can be solved.

[1] A step of melt-extruding a composition containing a thermoplastic resin from a die, and continuously pressing the melt-extruded melt between a first clamping surface and a second clamping surface constituting a clamping device. And forming the film-like melt into a film-like melt by applying a pressure of 5 to 1000 MPa to the central portion in the width direction of the film-like melt by the clamping device, A portion of 50 to 500 mm from one end is clamped without contacting at least one of the first clamping surface and the second clamping surface of the clamping device, and the moving speed of the first clamping surface is set to the second clamping surface. A method for producing a film, characterized in that the film is made faster than a moving speed of a pressing surface.
[2] In the step of continuously pressing the melt-extruded melt between a first clamping surface and a second clamping surface constituting the clamping device to form a film, the clamping devices are arranged around each other. The method for producing a film according to [1], wherein the two rolls have different speeds.
[3] In the method for producing a film according to [1] or [2], a portion of 50 to 500 mm from both ends of the film-like melt is placed between the first and second clamping surfaces of the clamping device. A method for producing a film, wherein the film is pressed without contacting at least one surface of the pressure surface.
[4] In the method for producing a film according to any one of [1] to [3], a portion of 50 to 500 mm from the end is formed between the first and second pressing surfaces of the pressing device. A method for producing a film, wherein the film is clamped while being brought into contact with only one surface.
[5] The moving speed ratio between the first clamping surface and the second clamping surface of the clamping device defined by the following formula (I) is 0.70 to 0.99, [1] to [1] 4] The manufacturing method of the film as described in any one of [4].
Movement speed ratio = speed of the second clamping surface / speed of the first clamping surface (I)
[6] The method for producing a film according to any one of [2] to [5], wherein the roll that is not in contact with the melt is a touch roll.
[7] The method for producing a film according to any one of [2] to [6], wherein the contact portion of the roll is crowned.
[8] The thermoplastic resin is at least one selected from a cyclic olefin resin, a cellulose acylate resin, a polycarbonate resin, a styrene resin, and an acrylic resin. [7] The method for producing a film according to any one of [7].
[9] A film produced by the method for producing a film according to any one of [1] to [8].
[10] In a plane containing a thermoplastic resin and including a film tilt direction and a film normal, retardation Re [0 °] at a wavelength of 550 nm measured from the normal, and a tilt of + 40 ° with respect to the normal Retardation Re [+ 40 °] measured from a different direction and retardation Re [−40 °] measured from a direction inclined by −40 ° with respect to the normal line, both of the following formulas (II) and (III): The film according to [9], wherein “the direction inclined by θ ° from the film normal” is a direction inclined in the film surface direction by θ ° from the normal direction to the inclination direction. is there).
60 nm ≦ Re [0 °] ≦ 300 nm (II)
40 nm ≦ | Re [+ 40 °] −Re [−40 °] | ≦ 300 nm (III)
[11] The film according to [9] or [10], wherein a variation ΔRe [0 °] in Re [0 °] of the film satisfies the following formula (IV):
ΔRe [0 °] ≦ 10 nm (IV)
[12] A polarizing plate comprising a polarizer and the film described in any one of [9] to [11].
[13] An optical compensation film using the film according to any one of [9] to [11].
[14] An antireflection film using the film according to any one of [9] to [11].
[15] A liquid crystal display device using the film according to any one of [9] to [11].

  ADVANTAGE OF THE INVENTION According to this invention, when it uses for a liquid crystal display, sufficient optical compensation can be implement | achieved, and a film with high uniformity of an optical characteristic and its manufacturing method can be provided. Specifically, the film having the above optical characteristics can realize sufficient optical compensation when used in a TN mode, ECB mode, or OCB mode liquid crystal display. For example, in a TN mode liquid crystal display, since the viewing angle is narrow, an optical compensation film (for example, WV film (Fuji Film)) provided with an optical compensation layer made of a liquid crystal composition that realizes optical compensation is usually polarized. When the film of the present invention is used, an optical compensation having an optical compensation layer made of a conventional liquid crystal composition can be used without using an optical compensation layer made of a liquid crystal composition. Viewing angle compensation can be performed more easily than those using a film. Moreover, the film of this invention can be provided with the manufacturing method of the film of this invention.

Hereinafter, the present invention will be described in more detail. 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 the present specification, the “film longitudinal direction” means the MD (machine direction) direction.
In this specification, the glass transition temperature is also referred to as Tg.

[the film]
(In-plane retardation Re)
The film of the present invention (hereinafter also referred to as the film of the present invention) contains a thermoplastic resin, and has a retardation Re [0 at a wavelength of 550 nm measured from the normal line in a plane including the film tilt direction and the film normal line. And retardation Re [+ 40 °] measured from a direction inclined + 40 ° and retardation Re [−40 °] measured from a direction inclined −40 ° with respect to the normal line are represented by the following formulas ( It is preferred to satisfy both II) and formula (III).
60 nm ≦ Re [0 °] ≦ 300 nm (II)
40 nm ≦ | Re [+ 40 °] −Re [−40 °] | ≦ 300 nm (III)

  In this specification, the “direction inclined by θ ° from the film normal” is defined as a direction inclined in the film surface direction by θ ° from the normal direction to the inclination direction. That is, the normal direction of the film surface is a direction with an inclination angle of 0 °, and an arbitrary direction within the film surface is a direction with an inclination angle of 90 °.

In the film of the present invention, | Re [+ 40 °] −Re [−40 °] | is preferably 60 to 200 nm, and more preferably 80 to 180 nm. The film of the present invention preferably has an in-plane retardation Re [0 °] of 60 to 250 nm, more preferably Re [0 °] of 60 to 200 nm, and still more preferably 80 to 180 nm. It is.
Further, the film of the present invention preferably has a thickness direction retardation Rth of 40 to 500 nm, more preferably 40 to 350 nm, and still more preferably 40 to 300 nm.
Furthermore, the film of the present invention preferably satisfies the following formulas (V) to (VII) at the same time.
60 nm ≦ Re [0 °] ≦ 200 nm (V)
60 nm ≦ | Re [+ 40 °] −Re [−40 °] | ≦ 250 nm (VI)
40 nm ≦ Rth ≦ 350 nm (VII)

  A film in which | Re [+ 40 °] -Re [−40 °] |, Re [0 °] and Rth are in the preferred ranges can be produced by the production method of the present invention described later. In addition, when the film having the above preferable optical characteristics is used for optical compensation of a liquid crystal display such as a TN mode, an ECB mode, and an OCB mode, it contributes to an improvement in viewing angle characteristics and achieves a wide viewing angle. Can do.

  The film thickness of the film of the present invention is preferably 100 μm or less. When used for a liquid crystal display or the like, from the viewpoint of thinning, it is more preferably 80 μm or less, particularly preferably 60 μm or less, and particularly preferably 40 μm or less. In the film manufacturing method of the present invention, such a thin film can be produced, which is one of the differences from the prior art.

(Re variation)
Variations in Re [0 °], Re [+ 40 °], and Re [−40 °] appear as display unevenness when used in a liquid crystal display. Therefore, the variation is preferably as small as possible. It is preferably within ± 3 nm, and more preferably within ± 1 nm.
Similarly, since the variation in the angle of the slow axis also causes display unevenness, the variation is preferably as small as possible, specifically within ± 1 °, and preferably within ± 0.5 °. It is more preferable that the angle is within ± 0.25 °.

The film of the present invention has a variation in Re [0 °] (hereinafter also referred to as ΔRe [0 °]) satisfying the following formula (IV) from the viewpoint of reducing unevenness of a display image when used in a liquid crystal display device. Therefore, it is preferable.
ΔRe [0 °] ≦ 10 nm (IV)
ΔRe [0 °] is more preferably 7 nm or less, and particularly preferably 5 nm or less.

The optical characteristic value can be measured by the following method.
In the present invention, Re [0 °], Re [+ 40 °] and Re [−40 °] of the film are measured using KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments Co., Ltd.). , The phase difference at an inclination angle of 0 °, the phase difference at an inclination angle of 40 degrees, and the phase difference at an inclination angle of −40 degrees were measured.
Here, the inclination direction was determined by the following method.
(1) The slow axis direction in the film plane is 0 °, the fast axis direction in the film plane is 90 °, and the temporary tilt direction is set in increments of 0.1 ° between 0 ° and 90 °.
(2) Re [+ 40 °] and Re [−40 °] are measured in a plane including each provisional tilt direction and the film normal to obtain | Re [+ 40 °] −Re [−40 °] |.
(3) The direction in which | Re [+ 40 °] −Re [−40 °] | is maximized is determined as the tilt direction.
The measurement wavelength is 550 nm. Note that a film made of a general thermoplastic resin by a melt film forming method has a value of | Re [+ 40 °] −Re [−40 °] | ≈0 nm regardless of the orientation. That is, when | Re [+ 40 °] −Re [−40 °] | is measured in the tilt direction, it is a feature of the film of the present invention that a phase difference of 0 nm or more is expressed.
In addition, variations in Re [0 °], Re [+ 40 °], and Re [−40 °] can be measured by the following method. Sampling is performed at any 10 or more positions on the film surface 2 mm or more away from each other, and Re [0 °], Re [+ 40 °] and Re [−40 °] are measured by the above method. The difference in value is defined as the variation of Re [0 °], Re [+ 40 °], and Re [−40 °]. In this application, the variation was measured at 10 points obtained by dividing the film width direction into 11 equal parts at an arbitrary position and 100 points sampled at 9 points at 0.2 m intervals from that point.
Further, the slow axis and the variation of Rth described later are measured in the same manner.

式中、Ｒｅ（θ）は法線方向から角度θ傾斜した方向におけるレターデーション値をあらわす。また、数式（Ｂ）中のβは、屈折率楕円体が一様傾斜したことを仮定した場合の傾斜角度を表し、傾斜型位相差フィルムの構造を単純に把握するときに使用される。
上記の測定において、平均屈折率の仮定値は、ポリマーハンドブック（ＪＯＨＮ ＷＩＬＥＹ＆ＳＯＮＳ，ＩＮＣ）、各種光学補償フィルムのカタログの値を使用することができる。また、平均屈折率の値が既知でないものについては、アッベ屈折計で測定することができる。主な光学補償フィルムの平均屈折率の値を以下に例示する：セルロースアシレート（１．４８）、シクロオレフィンポリマー（１．５２）、ポリカーボネート（１．５９）、ポリメチルメタクリレート（１．４９）、ポリスチレン（１．５９）である。 (Retardation Rth in film thickness direction)
Rth is calculated by calculating the refractive indices nx, ny, and nz in each direction of the refractive index ellipsoid and substituting them into the following formula (A), assuming that the refractive index ellipsoid is uniformly inclined by β °. be able to.
Rth = ((nx + ny) / 2−nz) × d Formula (A)
In the film of the present invention, ny is the refractive index in the film width direction. nx is the refractive index in the direction in which the projection component on the x-axis of the film is larger than the projection component on the z-axis, and nz is the refractive index in the direction in which the projection component on the z-axis is larger than the projection component on the x-axis.
The method for obtaining nx, ny, and nz is described in the technical data of Oji Scientific Instruments Co., Ltd. (http://www.oji-keisoku.co.jp/products/kobra/kobra.html). For example, it is possible to calculate from the values of Re [0 °], Re [+ 40 °] and Re [−40 °], the value of average refractive index n _ave , and the film thickness value d using the following formula (B). I can do it.

In the formula, Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. In addition, β in the mathematical formula (B) represents an inclination angle when it is assumed that the refractive index ellipsoid is uniformly inclined, and is used when the structure of the inclined retardation film is simply grasped.
In the above measurement, as the assumed value of the average refractive index, the values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical compensation films can be used. Moreover, about the thing whose average refractive index value is not known, it can measure with an Abbe refractometer. The average refractive index values of the main optical compensation films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49) Polystyrene (1.59).

(Thermoplastic resin)
The thermoplastic resin used in the present invention is not particularly limited as long as it has the above-mentioned optical characteristics. However, when it is produced using a melt extrusion method, it is preferable to use a material having good melt extrusion moldability. In, polyolefins such as cyclic olefin resins, cellulose acylate resins, polycarbonate resins, polyesters, transparent polyethylene, transparent polypropylene, polyarylates, polysulfones, polyethersulfones, maleimide copolymers, transparent It is preferable to select nylons, transparent fluororesins, transparent phenoxys, polyetherimides, polystyrenes, acrylic resins, and styrene resins. One kind of the resin may be contained, or two or more kinds of the resins different from each other may be contained. The film of the present invention preferably contains at least one of a cyclic olefin resin, a cellulose acylate resin, a polycarbonate resin, a styrene resin, and an acrylic resin. The cyclic olefins are preferably cyclic olefins obtained by addition polymerization.

In particular, when a cellulose acylate resin, a cyclic olefin resin, and a polycarbonate resin exhibiting positive intrinsic birefringence are subjected to shear deformation with two rolls, the slow axis faces the tilt direction, and | Re [ + 40 °] −Re [−40 °] |> 0 film can be produced. For example, when two rolls are arranged in parallel to the die exit, the tilt direction is the same as the film longitudinal direction.
Also, acrylic resin and styrene resin exhibiting negative intrinsic birefringence, when the above processing is performed, the fast axis is directed to the tilt direction, and | Re [+ 40 °] −Re [−40 °] | > 0 films can be created.

  When the film of the present invention is applied to a liquid crystal display device as a viewing angle compensation film, the positive or negative intrinsic birefringent resin is appropriately used in consideration of the characteristics of the liquid crystal display device and the convenience of polarizing plate processing. You can select and use.

Examples of the cyclic olefin resin that can be used in the present invention include a norbornene resin obtained by polymerization of a norbornene compound. Further, it may be a resin obtained by any polymerization method of ring-opening polymerization and addition polymerization.
Examples of the addition polymerization and the cyclic olefin-based resin obtained thereby include, for example, Japanese Patent No. 3517471, Japanese Patent No. 3559360, Japanese Patent No. 3867178, Japanese Patent No. 3871721, Japanese Patent No. 3907908, Japanese Patent No. 3945598, Special Table 2005 No. 5,276,696, JP-A-2006-28993, JP-A-2006-11361, International Publication No. WO 2006/004376, International Publication No. WO 2006/030797. Among these, those described in Japanese Patent No. 3517471 are particularly preferable.
Examples of the ring-opening polymerization and the cyclic olefin-based resin obtained thereby include International Publication WO 98/98499, pamphlet, Japanese Patent No. 30605532, Japanese Patent No. 3320478, Japanese Patent No. 3273046, Japanese Patent No. 3404027, Japanese Patent No. 3428176. , Japanese Patent No. 3687231, Japanese Patent No. 3873934, and Japanese Patent No. 3912159. Among these, those described in International Publication WO 98/14499 pamphlet and Japanese Patent No. 30605532 are particularly preferable.
Among these cyclic olefin-based resins, those obtained by addition polymerization are preferable from the viewpoint of the expression of birefringence and the melt viscosity. For example, “TOPAS # 6013” (manufactured by Polyplastics) can be used.

  Examples of the cellulose acylate resin that can be used in the present invention include any cellulose acylate in which three hydroxyl groups in a cellulose unit are at least partially substituted with an acyl group. The acyl group (preferably an acyl group having 3 to 22 carbon atoms) may be either an aliphatic acyl group or an aromatic acyl group. Among them, cellulose acylate having an aliphatic acyl group is preferable, those having an aliphatic acyl group having 3 to 7 carbon atoms are more preferable, those having an aliphatic acyl group having 3 to 6 carbon atoms are more preferable, and carbon number More preferably has 3 to 5 aliphatic acyl groups. A plurality of these acyl groups may be present in one molecule. Examples of preferred acyl groups include acetyl, propionyl, butyryl, pentanoyl, hexanoyl and the like. Among these, a cellulose acylate having one or more selected from an acetyl group, a propionyl group and a butyryl group is more preferable, and an even more preferable one has both an acetyl group and a propionyl group. Cellulose acylate (CAP). The CAP is preferable in terms of easy resin synthesis and high stability of extrusion molding.

When producing a film by the melt extrusion method including the production method of the present invention, the cellulose acylate used preferably satisfies the following formulas (S-1) and (S-2). Cellulose acylate satisfying the following formula has a low melting temperature and improved meltability, and is therefore excellent in melt extrusion film formation.
Formula (S-1) 2.0 ≦ X + Y ≦ 3.0
Formula (S-2) 0.25 <= Y <= 3.0
In the formulas (S-1) and (S-2), X represents the degree of substitution of the acetyl group with respect to the hydroxyl group of cellulose, and Y represents the sum of the degree of substitution of the acyl group with respect to the hydroxyl group of cellulose. The “degree of substitution” in the present specification means the total of the ratio of substitution of hydrogen atoms of hydroxyl groups at the 2-position, 3-position and 6-position of cellulose. When the hydrogen atoms of all hydroxyl groups at the 2nd, 3rd and 6th positions are substituted with acyl groups, the degree of substitution is 3.
Furthermore, it is more preferable to use a cellulose acylate that satisfies the following formulas (S-3) and (S-4).
Formula (S-3) 2.3 ≦ X + Y ≦ 2.95
Formula (S-4) 1.0 ≦ Y ≦ 2.95
It is more preferable to use a cellulose acylate that satisfies the following formulas (S-5) and (S-6).
Formula (S-5) 2.7 ≦ X + Y ≦ 2.95
Formula (S-6) 2.0 ≦ Y ≦ 2.9

  There is no restriction | limiting in particular about the mass average polymerization degree and number average molecular weight of a cellulose acylate-type resin. In general, the mass average degree of polymerization is about 350 to 800, and the number average molecular weight is about 70000 to 230,000. The cellulose acylate resin can be synthesized using an acid anhydride or acid chloride as an acylating agent. In the industrially most general synthesis method, cellulose obtained from cotton linter, wood pulp, etc. is converted into organic acids (acetic acid, propionic acid, butyric acid) corresponding to acetyl groups and other acyl groups, or their acid anhydrides (anhydrous anhydride). A cellulose ester is synthesized by esterification with a mixed organic acid component containing acetic acid, propionic anhydride, and butyric anhydride). As a method for synthesizing cellulose acylate satisfying the above formulas (S-1) and (S-2), the technical report of the Japan Society of Invention (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Invention) 7 Pp. 12 to 12, JP-A-2006-45500, JP-A-2006-241433, JP-A-2007-138141, JP-A-2001-188128, JP-A-2006-142800, JP-A-2007. Reference can be made to the method described in Japanese Patent No. 98917.

  Examples of polycarbonate resins that can be used in the present invention include polycarbonate resins having a bisphenol A skeleton, which are obtained by reacting a dihydroxy component and a carbonate precursor by an interfacial polymerization method or a melt polymerization method. JP-A-2006-277914, JP-A-2006-106386, and JP-A-2006-284703 can be preferably used. For example, “Taflon MD1500” (manufactured by Idemitsu Kosan Co., Ltd.) can be used as a commercial product.

The styrenic resin that can be used in the present invention refers to a resin obtained by polymerizing styrene and derivatives thereof as a main component, and copolymers of other resins, and is not particularly limited as long as the effects of the present invention are not impaired. A known styrene-based thermoplastic resin can be used, and a copolymer resin that can improve birefringence, film strength, and heat resistance is particularly preferable.
Examples of the copolymer resin include styrene-acrylonitrile resins, styrene-acrylic resins, styrene-maleic anhydride resins, and multi-component (binary, ternary, etc.) copolymer polymers thereof. Among these, a styrene-maleic anhydride resin is preferable from the viewpoint of film strength.
In the styrene-maleic anhydride resin, the mass composition ratio of styrene and maleic anhydride is preferably styrene: maleic anhydride = 95: 5 to 50:50, and styrene: maleic anhydride = 90: 10. More preferably, it is ˜70: 30. In order to adjust the intrinsic birefringence, hydrogenation of a styrene resin can be preferably used.
Examples of the styrene-maleic anhydride resin include “Daylark D332” manufactured by Nova Chemical Co., Ltd.

The acrylic resin that can be used in the present invention refers to a resin obtained by polymerizing acrylic acid, methacrylic acid and derivatives thereof as main components, and further derivatives thereof, as long as the effects of the present invention are not impaired. It does not specifically limit, A well-known methacrylic acid type thermoplastic resin etc. can be used.
Examples of the resin obtained by polymerizing acrylic acid, methacrylic acid and derivatives thereof include those having a structure represented by the following general formula (1).

前記一般式（１）中、Ｒ¹およびＲ²は、それぞれ独立に、水素原子または炭素数１〜２０の有機残基を示す。有機残基とは、具体的には、炭素数１〜２０の直鎖状、分枝鎖状、もしくは環状のアルキル基を示す。

In the general formula (1), R ¹ and R ² each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue specifically represents a linear, branched or cyclic alkyl group having 1 to 20 carbon atoms.

Specific examples of resins obtained by polymerizing the acrylic acid, methacrylic acid and derivatives thereof include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, and (meth) acrylic. N-butyl acid, tert-butyl (meth) acrylate, n-hexyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 3-hydroxy (meth) acrylate Propyl, 2,3,4,5,6-pentahydroxyexyl (meth) acrylate and 2,3,4,5-tetrahydroxypentyl (meth) acrylate are preferred, and in terms of excellent thermal stability (meta ) Methyl acrylate (hereinafter also referred to as MMA) is more preferable. Among these, only 1 type may be used and 2 or more types may be used together. Further, among these, it may be a single polymer, a copolymer of two or more, or a copolymer of other resins, but from the viewpoint of increasing the glass transition temperature, Particularly preferred is a copolymer with a resin.
Among the acrylic copolymer resins, those containing 30 mol% or more of MMA units (monomer) in all monomers constituting the resin are preferable. In addition to MMA, lactone ring units, maleic anhydride units, glutaric anhydrides More preferably, at least one unit of units is included, and for example, the following can be used.

(1) Acrylic resin containing a lactone ring unit JP 2007-297615 A, JP 2007-63541 A, JP 2007-70607 A, JP 2007-100044 A, JP 2007-254726 A, JP 2007-254727 A , JP 2007-261265, JP 2007-293272, JP 2007-297619, JP 2007-316366, JP 2008-9378, and JP 2008-76764. Can be used. Among these, the resin described in JP-A-2008-9378 is more preferable.
(2) Acrylic resin containing maleic anhydride unit JP 2007-113109 A, JP 2003-292714 A, JP 6-279546 A, JP 2007-51233 A (described here), JP JP-A-2001-270905, JP-A-2002-167694, JP-A-2000-302988, JP-A-2007-111110, JP-A-2007-11565 can be used. Among these, the one described in JP 2007-113109 A is more preferable. A commercially available maleic acid-modified MAS resin (for example, Delpet 980N manufactured by Asahi Kasei Chemicals Corporation) can also be preferably used.
(3) Acrylic resin containing glutaric anhydride unit JP-A-2006-241263, JP-A-2004-70290, JP-A-2004-70296, JP-A-2004-126546, JP-A-2004-163924, JP-A-2004 -291302, JP-A-2004-292812, JP-A-2005-314534, JP-A-2005-326613, JP-A-2005-331728, JP-A-2006-131898, JP-A-2006-134882, JP-A-2006- 206881, JP 2006-241197, JP 2006-283013, JP 2007-118266, JP 2007-176982, JP 2007-178504, JP 2007-197703, JP 2008-74818. No., International Publication WO2005 / 105 Those described in each publication such as 918 can be used. Among these, those described in JP-A-2008-74918 are more preferable.
The glass transition temperature (Tg) of these resins is preferably 106 ° C to 170 ° C, more preferably 110 ° C to 160 ° C, still more preferably 115 ° C to 150 ° C.

Among these, the thermoplastic resin is preferably a cyclic olefin resin, more preferably a norbornene resin from the viewpoint of high transparency, birefringence and heat resistance, and an addition polymerization type norbornene. It is particularly preferable that the resin is a series resin.
In addition, when the thermoplastic resin is a copolymer, it may be a random copolymer or a block copolymer.

(Additive)
The film of the present invention may contain a material other than the thermoplastic resin, but contains one or more of the thermoplastic resins as a main component (the highest content ratio among all the materials in the composition). In the aspect which means material and contains 2 or more types of the said resin, it is preferable to contain as the content ratio of those sum total being higher than the content rate of each other material. Examples of materials other than the thermoplastic resin include various additives, and examples thereof include a stabilizer, an ultraviolet absorber, a light stabilizer, a plasticizer, fine particles, and an optical adjusting agent.

Stabilizer:
The film of the present invention may contain at least one stabilizer. The stabilizer is preferably added before or when the thermoplastic resin is heated and melted. The stabilizer has effects such as preventing oxidation of the film constituting material, capturing an acid generated by decomposition, and suppressing or inhibiting a decomposition reaction caused by radical species caused by light or heat. Stabilizers are useful for suppressing the occurrence of alterations such as coloring and molecular weight reduction and the generation of volatile components due to various decomposition reactions including unresolved decomposition reactions. Even at the melting temperature for forming a resin film, the stabilizer itself is required to function without being decomposed. Typical examples of stabilizers include phenol-based stabilizers, phosphorous acid-based stabilizers (phosphite-based), thioether-based stabilizers, amine-based stabilizers, epoxy-based stabilizers, and lactone-based stabilizers. Stabilizers, amine stabilizers, metal deactivators (tin stabilizers) and the like are included. These are described in JP-A-3-199201, JP-A-5-1907073, JP-A-5-194789, JP-A-5-271471, JP-A-6-107854, and the like. Then, it is preferable to use at least one or more of a phenol-based or phosphorous acid-based stabilizer. Among phenolic stabilizers, it is particularly preferable to add a phenolic stabilizer having a molecular weight of 500 or more. Preferable phenolic stabilizers include hindered phenolic stabilizers.

  These materials are readily available as commercial products and are sold by the following manufacturers. From Ciba Specialty Chemicals, Irganox 1076, Irganox 1010, Irganox 3113, Irganox 245, Irganox 1135, Irganox 1330, Irganox 259, Irganox 565, Irganx 565, Irganx 565, Ir35x10 Moreover, it can obtain from Asahi Denka Kogyo Co., Ltd. as ADK STAB AO-50, ADK STAB AO-60, ADK STAB AO-20, ADK STAB AO-70, and ADK STAB AO-80. Furthermore, from Sumitomo Chemical Co., Ltd., it can obtain as Sumilizer BP-76, Sumilizer BP-101, Sumilizer GA-80. In addition, it is also possible to obtain as Sinox 326M and Sinox 336B from Sipro Kasei Co., Ltd.

  Moreover, as said phosphorous acid type stabilizer, the compound as described in [0023]-[0039] of Unexamined-Japanese-Patent No. 2004-182979 can be used more preferably. Specific examples of the phosphite ester stabilizer include JP-A-51-70316, JP-A-10-306175, JP-A-57-78431, JP-A-54-157159, Examples thereof include compounds described in Japanese Utility Model Laid-Open No. 55-13765. Furthermore, as other stabilizers, the materials described in detail on pages 17 to 22 of the Japan Institute of Invention Disclosure Bulletin (Public Technical No. 2001-1745, issued March 15, 2001, Japan Society of Invention) are preferably used. be able to.

  The phosphite stabilizer is useful to have a high molecular weight in order to maintain stability at high temperature, has a molecular weight of 500 or more, more preferably a molecular weight of 550 or more, and particularly a molecular weight of 600 or more. Is preferred. Furthermore, at least one substituent is preferably an aromatic ester group. The phosphite ester stabilizer is preferably a triester, and is desirably free of impurities such as phosphoric acid, monoester and diester. When these impurities are present, the content is preferably 5% by mass or less, more preferably 3% by mass or less, and particularly 2% by mass or less. These include compounds described in [0023] to [0039] of JP-A No. 2004-182979, JP-A-51-70316, JP-A-10-306175, JP-A-57. The compounds described in JP-A-78431, JP-A-54-157159, and JP-A-55-13765 can also be mentioned. Preferable specific examples of the phosphite ester stabilizer include the following compounds, but the phosphite ester stabilizer that can be used in the present invention is not limited thereto.

  These are commercially available from Asahi Denka Kogyo Co., Ltd. as ADK STAB 1178, 2112, PEP-8, PEP-24G, PEP-36G, and HP-10, and Sandostab P-EPQ from Clariant. Is possible. Furthermore, a stabilizer having phenol and phosphite in the same molecule is also preferably used. These compounds are further described in detail in JP-A-10-273494. Examples of the compounds are included in the examples of the stabilizer, but are not limited thereto. As a typical commercial product, Sumitizer GP is available from Sumitomo Chemical Co., Ltd. These are commercially available from Sumitomo Chemical Co., Ltd. as Sumilizer TPL, TPM, TPS, TDP. Also available from Asahi Denka Kogyo Co., Ltd. as ADK STAB AO-412S.

  The stabilizers can be used alone or in combination of two or more, and the blending amount thereof is appropriately selected within a range not impairing the object of the present invention. Preferably, the addition amount of the stabilizer is preferably 0.001 to 5% by mass, more preferably 0.005 to 3% by mass, and still more preferably 0.01 to 0% with respect to the mass of the thermoplastic resin. 0.8% by mass.

UV absorber:
The film of this invention may contain the 1 type (s) or 2 or more types of ultraviolet absorber. From the viewpoint of preventing deterioration, the ultraviolet absorbent is preferably excellent in the ability to absorb ultraviolet light having a wavelength of 380 nm or less and has little absorption of visible light having a wavelength of 400 nm or more from the viewpoint of transparency. Examples include oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, nickel complex compounds, and the like. Particularly preferred ultraviolet absorbers are benzotriazole compounds and benzophenone compounds. Among these, a benzotriazole-based compound is preferable because unnecessary coloring with respect to the cellulose mixed ester is small. These are disclosed in JP-A-60-235852, JP-A-3-199201, 5-1907073, 5-194789, 5-271471, 6-107854, 6-118233, 6 -148430, 7-11056, 7-11055, 7-11056, 8-29619, 8-239509, and JP-A-2000-204173.
The addition amount of the ultraviolet absorber is preferably 0.01 to 2% by mass of the thermoplastic resin, and more preferably 0.01 to 1.5% by mass.

Light stabilizer:
The film of the present invention may contain one or more light stabilizers. Light stabilizers include hindered amine light stabilizer (HALS) compounds, more specifically, US Pat. No. 4,619,956, columns 5-11 and US Pat. No. 4,839. 2,405, 2,2,6,6-tetraalkylpiperidine compounds, or their acid addition salts or complexes of them with metal compounds. These are commercially available from Asahi Denka as ADK STAB LA-57, LA-52, LA-67, LA-62, LA-77, and TINUVIN 765, 144 from Ciba Specialty Chemicals. .

  These hindered amine light stabilizers can be used alone or in combination of two or more. These hindered amine light stabilizers may of course be used in combination with additives such as plasticizers, stabilizers, UV absorbers, etc., or may be introduced into a part of the molecular structure of these additives. Good. The blending amount is determined within a range not impairing the effects of the present invention, and is generally about 0.01 to 20 parts by mass, preferably 0.02 to 15 parts per 100 parts by mass of the thermoplastic resin. About mass parts, and particularly preferably about 0.05 to 10 mass parts. The light stabilizing agent may be added at any stage of preparing the melt of the thermoplastic resin composition, for example, at the end of the melt preparation process.

Plasticizer:
The film of the present invention may contain a plasticizer. The addition of a plasticizer is preferable from the viewpoint of film modification such as improvement of mechanical properties, imparting flexibility, imparting water absorption resistance, and reducing moisture permeability. In addition, when the film of the present invention is produced by a melt film-forming method, for the purpose of lowering the melting temperature of the film constituting material by adding a plasticizer rather than the glass transition temperature of the thermoplastic resin used, or without addition Will be added for the purpose of lowering the viscosity at the same heating temperature than the other thermoplastic resins. For the film of the present invention, for example, a plasticizer selected from phosphoric acid ester derivatives and carboxylic acid ester derivatives is preferably used. Further, a polymer obtained by polymerizing an ethylenically unsaturated monomer having a weight average molecular weight of 500 to 10,000 described in JP-A-2003-12859, an acrylic polymer, an acrylic polymer having an aromatic ring in the side chain, or a cyclohexyl group An acrylic polymer or the like having in the side chain is also preferably used.

Fine particles:
The film of the present invention may contain fine particles. Examples of the fine particles include fine particles of inorganic compounds and fine particles of organic compounds, and any of them may be used. The average primary particle size of the fine particles contained in the thermoplastic resin in the present invention is preferably 5 nm to 3 μm, more preferably 5 nm to 2.5 μm, more preferably 10 nm to 2.0 μm from the viewpoint of keeping haze low. More preferably. Here, the average primary particle size of the fine particles is determined by observing the thermoplastic resin with a transmission electron microscope (magnification of 500,000 to 1,000,000 times) and determining the average value of the primary particle sizes of 100 particles. The addition amount of the fine particles is preferably 0.005 to 1.0% by mass with respect to the thermoplastic resin, more preferably 0.01 to 0.8% by mass, and further preferably 0.02 to 0%. 4% by mass.

Optical modifier:
The film of the present invention may contain an optical adjusting agent. Examples of the optical adjusting agent include a retardation adjusting agent, for example, those described in JP-A Nos. 2001-166144, 2003-344655, 2003-248117, and 2003-66230. Can be used. By adding an optical adjusting agent, in-plane retardation (Re) and thickness direction retardation (Rth) can be controlled. A preferable addition amount is 0 to 10% by mass, more preferably 0 to 8% by mass, and further preferably 0 to 6% by mass.

[Film Production Method]
The film production method of the present invention includes a step of melt-extruding a composition containing a thermoplastic resin from a die, and a melt-extruded melt between a first clamping surface and a second clamping surface constituting a clamping device. A film including a step of continuously pressing to form a film-like melt, a pressure of 5 to 1000 MPa is applied to the central portion in the width direction of the film-like melt by the pressing device, A portion of 50 to 500 mm from at least one end of the film-like melt is clamped without contacting at least one of the first clamping surface and the second clamping surface of the clamping device, and The moving speed is made faster than the moving speed of the second clamping surface.
Conventionally, a melt-extruded melt is continuously pressed between the first and second clamping surfaces constituting the clamping device to form a film, and the film is conveyed by tension applied in the conveyance direction. The melt flowed at the end of the melt and swelled at the end of the film (Neckin phenomenon). When such a bulge at the end of the film exists, it is difficult to increase the pressure between the pressing devices because the pressure at the center of the film-like melt does not increase even if the roll pressure is increased. In the present invention, the end of the film-like melt that does not swell is not brought into contact with the first and second clamping surfaces of the clamping device, so that the pressure between the clamping devices is not increased by the swelling of the film end. Uniformity is eliminated, and a large pressure between the pressing devices can be applied evenly in the film width direction. It is a feature of the present invention that differs from the conventional method in that the pressure between the clamping devices is equally large in the film width direction. Examples of the clamping device having different speeds on the first clamping surface and the second clamping surface include, for example, a combination of two rolls having different peripheral speeds, and rolls having different speeds described in Japanese Patent Application Laid-Open No. 2000-219752. Examples include a combination of touch belts (single-sided belt method), a combination of belts and belts (double-sided belt method), and the like. Among these, since it is possible to uniformly apply a high pressure of 20 to 500 MPa, it is preferable that the two rolls have different peripheral speeds. The roll pressure can be measured by passing a pressure measurement film (such as a prescale for medium pressure by Fuji Film) through two rolls.
Hereinafter, the film production method of the present invention (hereinafter also referred to as the production method of the present invention) will be described in detail.

<Melting extrusion>
In the production method of the present invention, first, a composition containing a thermoplastic resin (sometimes referred to as a “thermoplastic resin composition”) is melt-extruded. Prior to melt extrusion, the thermoplastic resin composition is preferably pelletized. Commercially available thermoplastic resins (for example, TOPAS # 6013, Toughlon MD1500, Delpet 980N, DayLark D332, etc.) may be pelletized, but if not pelletized, the following method may be used. it can.
The thermoplastic resin composition is dried, melted at 150 ° C. to 300 ° C. using a twin-screw kneading extruder, and then extruded into noodles, and solidified in air or water and cut. Further, after melting by an extruder, it can be pelletized by an underwater cutting method in which it is cut while being directly extruded from a die into water. Extruders used for pelletization include single screw extruders, non-meshing different direction rotating twin screw extruders, meshing different direction rotating twin screw extruders, and meshing same direction rotating twin screw extruders. Etc. can be used. The number of revolutions of the extruder is preferably 10 rpm to 1000 rpm, more preferably 20 rpm to 700 rpm. The extrusion residence time is 10 seconds to 10 minutes, more preferably 20 seconds to 5 minutes.
No particular limitation is imposed on the size of the pellets is generally about 10mm ³ ~1000mm ^3, more preferably about 30 mm ³ 500 mm ^3.

  It is preferred to reduce the moisture in the pellets prior to melt extrusion. A preferable drying temperature is 40 to 200 ° C, more preferably 60 to 150 ° C. Thereby, the moisture content is preferably 1.0% by mass or less, and more preferably 0.1% by mass or less. Drying may be performed in air, nitrogen, or vacuum.

  Next, the dried pellets are supplied into the cylinder through the supply port of the extruder, and are kneaded and melted. The inside of the cylinder is composed of, for example, a supply unit, a compression unit, and a measurement unit in order from the supply port side. The screw compression ratio of the extruder is preferably 1.5 to 4.5, the ratio of the cylinder length to the cylinder inner diameter (L / D) is preferably 20 to 70, and the cylinder inner diameter is preferably 30 mm to 150 mm. The extrusion temperature (hereinafter also referred to as the discharge temperature) is determined according to the melting temperature of the thermoplastic resin, but generally about 190 to 300 ° C. is preferable. Furthermore, in order to prevent the molten resin from being oxidized by residual oxygen, it is also preferable to carry out the inside of the extruder in an inert (nitrogen or the like) air flow or while evacuating using an extruder with a vent.

  It is preferable to provide a filtration apparatus incorporating a breaker plate type filtration or a leaf type disk filter for filtering foreign matter in the thermoplastic resin composition. Filtration may be performed in one stage or may be performed in multistage filtration. The filtration accuracy is preferably 15 μm to 3 μm, more preferably 10 μm to 3 μm. It is desirable to use stainless steel as the filter medium. As the configuration of the filter medium, a knitted wire, a sintered metal fiber or metal powder (sintered filter medium) can be used, and among them, a sintered filter medium is preferable.

  In order to reduce the fluctuation of the discharge amount and improve the thickness accuracy, it is preferable to provide a gear pump between the extruder and the die. Thereby, the resin pressure fluctuation width in the die can be within ± 1%. In order to improve the quantitative supply performance by the gear pump, a method of controlling the pressure before the gear pump to be constant by changing the number of rotations of the screw can also be used.

  The molten resin is melted by the extruder configured as described above, and the molten resin is continuously fed to the die via a filter and a gear pump as necessary. The die may be any of a T die, a fish tail die, and a hanger coat die. It is also preferable to insert a static mixer immediately before the die to increase the uniformity of the resin temperature.

The clearance of the die exit portion is generally 1.0 to 30 times the film thickness, preferably 5.0 to 20 times.
In the manufacturing method of the present invention, the radius of curvature of the tip of the die lip is not particularly limited, and a known die can be used.

It is preferable that the die can be adjusted in thickness at intervals of 5 to 50 mm. Also effective is an automatic thickness adjustment die that calculates downstream film thickness and thickness deviation and feeds back the results to die thickness adjustment.
In addition to the single layer film forming apparatus, it is also possible to manufacture using a multilayer film forming apparatus.
Thus, the residence time from when the resin enters the extruder through the supply port until it exits from the die is preferably 3 to 40 minutes, more preferably 4 to 30 minutes.

<Cast>
Next, the melt of the thermoplastic resin is extruded from the die into a film, and the melt-extruded melt is continuously sandwiched between the first sandwiching surface and the second sandwiching surface constituting the sandwiching device, and then cooled and solidified. To obtain a film. At this time, from the viewpoint of stabilization of productivity, one of the first clamping surface and the second clamping surface is peeled off from the melt first, and then the melt is peeled off from the other surface. preferable. In the manufacturing method of the present invention, the moving speed of the first pressing surface is faster than the moving speed of the second pressing surface, but the surface to be peeled first is the second pressing surface even if it is the first pressing surface. However, from the viewpoint of suppressing the peeling dan, it is preferable that the first surface to be peeled first is the first pinching surface (pressing surface having a high moving speed).

  In the production method of the present invention, in addition to the conventional method of forming a film by continuously pressing the melt-extruded melt between the first and second clamping surfaces constituting the clamping device, The film which has the optical characteristic of this invention is produced by applying a pressure to the center part of the width direction of this film-form melt with a pressure apparatus at 5-1000 Mpa. The pressure is preferably 20 to 500 MPa, more preferably 25 to 200 MPa, and particularly preferably 30 to 150 MPa.

In the manufacturing method of the present invention, the moving speed ratio of the first clamping surface and the second clamping surface of the clamping device defined by the following formula (I) is adjusted to 0.70 to 0.99, and the molten resin is sandwiched. It is preferable to apply a shear stress when passing through the pressure device to produce the film of the present invention. The moving speed ratio of the clamping device is more preferably 0.75 to 0.98.
Movement speed ratio = speed of the second clamping surface / speed of the first clamping surface (I)

In the production method of the present invention, the portion of 50 to 500 mm from the end of the film-like melt is pinched without contacting at least one of the first pinching surface and the second pinching surface of the pinching device. Hereinafter, the portion of the film-like melt that is clamped by the clamping device without contacting the first clamping surface or the second clamping surface of the clamping device is also referred to as a non-contact portion. If the non-contact portion is 50 mm or more, the portion where the bulging of the film end is not noticeable is not pinched by the pinching device. . In addition, it is preferable that the non-contact portion is 500 mm or less, because the film-like melt is sufficiently pressed onto the first clamping surface or the second clamping surface of the clamping device, and film formation is easy.
It is possible to press the portions of 50 to 500 mm from both ends of the film-like melt without bringing them into contact with at least one of the first and second pressing surfaces of the pressing device. More preferable from the viewpoint.
The first pressing surface of the pressing device of the film or the pressing is performed by bringing a portion of 50 to 500 mm from the end portion into contact with only one of the first pressing surface and the second pressing surface of the pressing device. This is particularly preferable from the viewpoint of adhesion to the second clamping surface.

  The non-contact portion is preferably 60 to 400 mm, more preferably 70 to 350 mm, and particularly preferably 80 to 300 mm.

(Discharge temperature)
In the production method of the present invention, the discharge temperature (resin temperature at the die outlet) is preferably Tg + 50 to Tg + 200 ° C., more preferably Tg + 70 to Tg + 180 ° C., from the viewpoint of improving the moldability of the resin and suppressing deterioration. Tg + 90 to Tg + 150 ° C. is particularly preferable. That is, if Tg + 50 ° C. or higher, the viscosity of the resin is sufficiently low and the moldability is good, and if Tg + 200 ° C. or lower, the resin is less likely to deteriorate.

(Air gap)
In the production method of the present invention, the air gap (distance from the die outlet to the melt landing point of the pinching device) is preferably as close as possible from the viewpoint of heat retention of the melt between the die and the pinching device, Specifically, the thickness is preferably 10 to 300 mm, more preferably 20 to 250 mm, and particularly preferably 30 to 200 mm.

(Line speed)
In the production method of the present invention, from the viewpoint of heat retention of the melt in the air gap, the line speed (film forming speed) is preferably 2 m / min or more, more preferably 5 m / min or more, and 10 m / min. The above is particularly preferable. When the line speed is increased, cooling of the melt in the air gap can be suppressed, and more uniform shear deformation can be imparted by the pinching device while the melt temperature is high. The line speed represents the speed at which the melt passes between the clamping apparatuses and the film conveyance speed in the conveyance apparatus.

  In the production method of the present invention, the width of the film-like melt is, for example, preferably 200 to 3000 mm, more preferably 250 to 2500 mm, and particularly preferably 300 to 2000 mm.

(Cast using two rolls)
Among the methods in which the melt-extruded melt is continuously pressed between a first pressing surface and a second pressing surface constituting a pressing device to form a film, two rolls (for example, a touch roll ( It is preferable to pass between the first roll) and the chill roll (second roll)). In addition, in this specification, when it has multiple casting rolls which convey the said melt, the casting roll nearest to the most upstream die | dye is also called a chill roll. Hereinafter, the preferable aspect of the manufacturing method of this invention using two rolls is demonstrated.

In the method for producing a film of the present invention, there is no particular limitation on the landing point of the melt extruded from the die, and the landing point of the melt extruded from the die is closest to the touch roll and the cast roll. The distance from the vertical line passing through the midpoint of the gap in the portion may be zero or may be shifted.
The landing point of the melt refers to a point where the melt extruded from the die comes into contact (landing) with the touch roll or chill roll for the first time. The midpoint of the gap between the touch roll and the cast roll refers to the midpoint of the touch roll surface and the cast roll surface where the gap between the touch roll and the cast roll is the narrowest.

In the production method of the present invention, a portion of 50 to 500 mm from the end of the film-like melt is passed between the two rolls without contacting at least one of the two rolls. Hereinafter, the portion of the film melt that passes between the two rolls without contacting the two rolls is also referred to as a non-contact portion. If the non-contact portion is 50 mm or more, the portion where the bulging of the film end is not noticeable is not sandwiched between the rolls, so that the pressure at the center of the roll can be increased and the phase difference is easily developed. Moreover, if the non-contact part is 500 mm or less, it is preferable because the film is sufficiently pressure-bonded to a roll and easy to form a film.
From the viewpoint of retardation development, it is more preferable to pass a portion of 50 to 500 mm from both ends of the film-like melt between the two rolls without contacting at least one of the two rolls.
It is particularly preferable from the viewpoint of adhesion of the film to the roll that a portion of 50 to 500 mm from the end is brought into contact with only one of the two rolls and passed between the two rolls.
The roll that is not in contact with the melt is a touch roll, that is, only the roll that is not the touch roll is brought into contact with the portion of 50 to 500 mm from the end portion and passed between the two rolls.
It is more particularly preferable from the viewpoint of the handleability of the film.
The preferable range of the non-contact portion is the same as the preferable general range of the above-described clamping device even in the case of casting using two rolls.

In the production method of the present invention, in addition to the conventional method of passing a film-like melt between two rolls rotating at different peripheral speeds, the roll pressure is set to 5 to 1000 MPa at the center of the film-like melt. By applying the film, the film having the optical characteristics of the present invention is produced. A preferable roll pressure is 20 to 500 MPa, more preferably 25 to 200 MPa, and particularly preferably 30 to 150 MPa.
The roll pressure and the pressure distribution in the width direction can be measured using a pressure measurement film (such as a prescale for medium pressure manufactured by Fuji Film).

  In the manufacturing method of the present invention, in order to pressurize the roll pressure in the above range, the cylinder set value is appropriately changed. Although the said cylinder setting value changes also with the resin material to be used and the material of two rolls, for example, when the effective width of a film-form melt is 330 mm, it is preferable that it is 1-30KN, and is 2.5-20KN. It is more preferable. When the effective width of the film-like melt is 1000 mm, it is preferably 2 to 100 KN, and more preferably 4 to 40 KN. For example, when the effective width of the film-like melt is 1800 mm, it is preferably 5 to 200 KN, more preferably 10 to 100 KN. Moreover, there is no restriction | limiting in particular in the roll which pressurizes roll pressure, Even if it only applies and pressurizes only to a touch roll, it applies to both a touch roll and a chill roll, pressurizes and pressurizes only to a chill roll. Also good.

In the production method of the present invention, in order to pressurize the roll pressure in the above range, it is preferable to use a roll having a roll hardness of 45 HS or more. The Shore hardness of the two preferable rolls is preferably 50 HS or more, and more preferably 60 to 90 HS.
The Shore hardness can be determined from the average value of values measured at 5 points in the roll width direction and 5 points in the circumferential direction using the method of JIS Z 2246.

  The material of the two rolls is preferably a metal from the viewpoint of achieving the Shore hardness, more preferably stainless steel, and a roll whose surface is plated is also preferred. Moreover, if the material of two rolls is a metal, since the surface unevenness | corrugation is small and the surface of a film is hard to be damaged, it is preferable. On the other hand, a rubber roll or a metal roll lined with rubber can be used without particular limitation as long as the roll pressure can be achieved.

  As for the touch roll, for example, JP-A-11-314263, JP-A-2002-36332, JP-A-11-235747, WO97 / 28950, JP-A-2004-216717, JP The thing of 2003-145609 gazette can be utilized.

There is no restriction | limiting in particular as a shape of a roll which has a part which does not contact a film-form melt in the said two rolls, The roll of a width | variety and the step which are the extent which 50-500 mm part does not contact from a film-form melt end part Examples thereof include rolls and rolls that have been crowned. Among them, it is preferable to use a roll in which the contact portion is crowned from the viewpoint of uniformizing the pressure in the roll width direction, and the width is such that a portion of 50 to 500 mm from the end of the film-like melt does not contact, It is more preferable to use a roll whose contact portion is crowned. In addition, about a crown amount, it can set so that it may not be contrary to the meaning of the manufacturing method of this invention according to the film thickness of the film to manufacture.
Moreover, although it may be a shape which does not contact both ends of a film-like melt by the said structure, or a shape which does not contact only one edge part, it is a film which is a shape which does not contact both edge parts. From the viewpoint of increasing the pressure at the center and applying pressure uniformly in the film width direction.

  The surfaces of the two rolls preferably have an arithmetic average height Ra of 100 nm or less, more preferably 50 nm or less, and still more preferably 25 nm or less.

Furthermore, in the production method of the present invention, by adjusting the peripheral speed ratio of the two rolls through which the film-like melt passes, a shear stress is applied when the molten resin passes through the two rolls. A film is manufactured. The peripheral speed ratio is preferably 0.70 to 0.99, and more preferably 0.75 to 0.98. Here, the peripheral speed ratio of the two rolls is defined by the following formula (I) ′.
Peripheral speed ratio = slow roll peripheral speed / fast roll peripheral speed Formula (I) ′

If the peripheral speed ratio of the two rolls is 0.70 or more, the absolute value of the difference between Re [+ 40 °] and Re [−40 °] of the obtained film becomes large and satisfies the above formula (III). This is preferable. If the peripheral speed ratio is 0.60 or more, it is preferable that the surface of the obtained film is hardly damaged. It is preferable to set the peripheral speed ratio of the two rolls to 0.70 to 0.99, since it is difficult to damage the film surface and a film having good smoothness can be stably produced.
In order to obtain the film of the present invention, whichever speed of the two rolls may be high, when the touch roll is slow, the bank is formed on the touch roll side. Formed residue) is formed. Since the touch roll has a short contact time with the melt, the bank formed on the touch roll side cannot be sufficiently cooled, and a peeling dan is generated, which easily causes a surface failure. Therefore, it is preferable that the slow roll is a chill roll (second roll) and the fast roll is a touch roll (first roll).

  Furthermore, in the production method of the present invention, it is preferable to use a roll having a large diameter as each of the two rolls. Specifically, two rolls having a diameter of 350 to 600 nm, more preferably 350 to 500 nm are used. Is preferred. When a roll with a large diameter is used, the contact area between the film-like melt and the roll becomes wide, and the time for shearing becomes longer. Therefore, a film with a large difference between Re [+ 40 °] and Re [−40 °] is used. , Re [0 °] can be manufactured while suppressing variations. In the production method of the present invention, the diameters of the two rolls may be the same or different.

  In the manufacturing method of the present invention, the two rolls are driven at different peripheral speeds. The two rolls may be driven or driven independently, but in order to suppress variations in Re [0 °], the two rolls are preferably driven independently.

Further, in order to increase the difference between Re [40 °] and Re [−40 °], the surface temperature of the two rolls may be made different. A preferable temperature difference is 5 ° C to 80 ° C, more preferably 20 ° C to 80 ° C, and further preferably 20 ° C to 60 ° C. At that time, the temperature of the two rolls is Tg−70 ° C. to Tg + 20 ° C., more preferably Tg−50 ° C. to Tg + 10 ° C., more preferably Tg−40 ° C. to Tg + 5 ° C., using the glass transition temperature Tg of the resin. Set to. Such temperature control can be achieved by passing a temperature-controlled liquid or gas through the touch roll.
The glass transition temperature of the thermoplastic resin is measured by adding a resin to a measurement pan using a scanning differential calorimeter (DSC) and raising the temperature from 30 ° C. to 300 ° C. at 10 ° C./min in a nitrogen stream. (1st-run), and then cooled to 30 ° C. at −10 ° C./min, and again heated from 30 ° C. to 300 ° C. at 10 ° C./min (2nd-run). The temperature at which the baseline starts to deviate from the low temperature side in 2nd-run can be obtained as the glass transition temperature (Tg).

In the production method of the present invention, the melt is preferably kept warm until the melt is extruded from the die and comes into contact with at least one of the two rolls to reduce the temperature distribution in the width direction. The temperature distribution in the direction is preferably within 5 ° C. In order to reduce the temperature distribution, a member having a heat insulating function or a heat reflecting function is disposed in at least a part of the passage between the melt die and the two rolls to shield the melt from the outside air. Is preferred. Thus, by arranging the heat insulating member in the passage and shielding it from the outside air, it is possible to suppress the influence of the external environment, for example, wind, and to suppress the temperature distribution in the width direction of the film. The temperature distribution in the width direction of the film-like melt is more preferably within ± 3 ° C., and even more preferably within ± 1 ° C.
Furthermore, when the said shielding member is used, since it can pass between rolls in the state with the high temperature of a film-form melt, ie, a state with low melt viscosity, there also exists an effect which is easy to produce the film of this invention.
The temperature distribution of the film-like melt can be measured with a contact thermometer or a non-contact thermometer.

The said shielding member is provided inside the both ends of two rolls, for example, via the width direction side surface of die | dye, and a clearance gap. The shielding plate may be directly fixed to the side surface of the die, or may be supported and fixed by a support member. For example, the width of the shielding member is preferably equal to or greater than the width of the side surface of the die so that the rising airflow due to heat dissipation of the die can be efficiently blocked.
The gap between the shielding member and the end in the width direction of the film-like melt is preferably narrow so as to efficiently shield the rising airflow flowing along the surface of the roll. More preferably, it is about 50 mm from the part. Note that the gap between the side surface of the die and the shielding member is not necessarily provided, but is preferably formed to an extent that allows airflow in the space surrounded by the shielding member to be discharged, for example, 10 mm or less.
In addition, as the material having a heat insulating function and / or a heat reflecting function, a material excellent in wind insulation and heat retention is preferable. For example, a metal plate such as stainless steel can be preferably used.

  As a method for eliminating the variation of Re [0 °], there is a method for improving the adhesion when the film-like melt comes into contact with the casting roll. Specifically, the adhesion can be improved by combining electrostatic application method, air knife method, air chamber method, vacuum nozzle method and the like. Such an adhesion improving method may be performed on the entire surface of the film-like melt or may be partially performed.

  After film formation in this way, it is preferable to cool the film by using one or more casting rolls in addition to two rolls (for example, a casting roll and a touch roll) that allow the film-like melt to pass through. The touch roll is usually arranged so as to touch the first casting roll on the most upstream side (closer to the die). In general, it is relatively common to use three cooling rolls, but this is not a limitation. The distance between the plurality of casting rolls is preferably 0.3 mm to 300 mm, more preferably 1 mm to 100 mm, and still more preferably 3 mm to 30 mm between the surfaces.

Further, it is preferable to trim both ends of the processed film. The portion cut off by trimming may be crushed and used again as a raw material. Further, it is also preferable to perform a thickness increasing process (knurling process) on one or both ends. The height of the unevenness due to the thickness increasing process is preferably 1 μm to 50 μm, more preferably 3 μm to 20 μm. Thickening processing may be convex on both sides or convex on one side. The width of the thickness increasing process is preferably 1 mm to 50 mm, more preferably 3 mm to 30 mm. Extrusion can be performed at room temperature to 300 ° C. It is also preferable to attach a lami film on one side or both sides before winding. The thickness of the laminated film is preferably 5 μm to 100 μm, more preferably 10 μm to 50 μm. The material is not particularly limited, such as polyethylene, polyester, and polypropylene.
The winding tension is preferably 2 kg / m width to 50 kg / width, more preferably 5 kg / m width to 30 kg / width.
The film thickness of the film obtained by the production method of the present invention when unstretched is preferably 100 μm or less. When used for a liquid crystal display or the like, from the viewpoint of thinning, it is more preferably 80 μm or less, particularly preferably 60 μm or less, and particularly preferably 40 μm or less.

<Stretching and relaxation treatment>
Furthermore, after film formation by the above method, stretching and / or relaxation treatment may be performed. For example, each process can be implemented by the following combinations (a) to (g).
(A) transverse stretching (b) transverse stretching → relaxation treatment (c) longitudinal stretching (d) longitudinal stretching → relaxation treatment (e) longitudinal (transverse) stretching → lateral (longitudinal) stretching (f) longitudinal (transverse) stretching → lateral (Longitudinal) stretching → relaxation treatment (g) Transverse stretching → relaxation treatment → longitudinal stretching → relaxation treatment Among these, the steps (a) to (d) are particularly preferable.

The transverse stretching can be performed using a tenter. That is, the film is stretched by holding both ends in the width direction with clips and widening the film in the lateral direction. At this time, the stretching temperature can be controlled by sending wind at a desired temperature into the tenter. The stretching temperature is preferably Tg-10 ° C to Tg + 60 ° C, more preferably Tg-5 ° C to Tg + 45 ° C, and further preferably Tg-10 ° C to Tg + 20 ° C or less. Moreover, a preferable lateral stretch ratio is 1.2 to 3.0 times, more preferably 1.2 to 2.5 times, and still more preferably 1.2 to 2.0 times.
By performing preheating before stretching and heat setting after stretching, the Re and Rth distribution after stretching can be reduced, and the variation in orientation angle associated with bowing can be reduced. Either preheating or heat setting may be performed, but both are more preferable. These preheating and heat setting are preferably performed by holding with a clip, that is, preferably performed continuously with stretching.
Preheating can be performed at a temperature about 1 ° C to 50 ° C higher than the stretching temperature, preferably 2 ° C to 40 ° C or less, more preferably 3 ° C to 30 ° C. The preheating time is preferably 1 second to 10 minutes, more preferably 5 seconds to 4 minutes, and even more preferably 10 seconds to 2 minutes. During preheating, it is preferable to keep the width of the tenter substantially constant. Here, “substantially” refers to ± 10% of the width of the unstretched film.
The heat setting can be performed at a temperature lower by 1 ° C. to 50 ° C. than the stretching temperature, more preferably 2 ° C. to 40 ° C., further preferably 3 ° C. to 30 ° C. More preferably, it is less than the stretching temperature and less than Tg. The preheating time is preferably 1 second to 10 minutes, more preferably 5 seconds to 4 minutes, and even more preferably 10 seconds to 2 minutes. During the heat setting, it is preferable to keep the width of the tenter substantially constant. Here, “substantially” refers to 0% (the same width as the tenter width after stretching) to −10% (shrinking by 10% from the tenter width after stretching = reduced width) of the tenter width after stretching. If the width is wider than the stretched width, residual strain tends to occur in the film, which is not preferable.

Longitudinal stretching can be achieved by making the peripheral speed on the outlet side faster than the peripheral speed on the inlet side while heating between two pairs of rolls. Under the present circumstances, the expression of the retardation of the thickness direction can be changed by changing the space | interval (L) between and the film width (W) before extending | stretching. When L / W (referred to as aspect ratio) is 2 to 50 or less (long span stretching), it is easy to produce a film having a small Rth, and when L / W is 0.01 to 0.3 (short span), a film having a large Rth is used. Can be created. In this embodiment, any of long span stretching, short span stretching, and a region between them (intermediate stretching = L / W exceeds 0.3 and 2 or less) may be used. Span stretching and short span stretching are preferred. Further, when aiming at high Rth, it is more preferable to use short span stretching, and when aiming at low Rth, it is distinguished from long span stretching.
The stretching temperature is preferably Tg-10 ° C to Tg + 60 ° C, more preferably Tg-5 ° C to Tg + 45 ° C, and further preferably Tg-10 ° C to Tg + 20 ° C or less. Moreover, a preferable lateral stretch ratio is 1.2 to 3.0 times, more preferably 1.2 to 2.5 times, and still more preferably 1.2 to 2.0 times.

Furthermore, dimensional stability can be improved by performing relaxation treatment after these stretching. Thermal relaxation is preferably performed either after film formation, after longitudinal stretching, or after lateral stretching, or both. The relaxation treatment may be performed online continuously after stretching, or may be performed offline after winding after stretching.
Thermal relaxation is (Tg-30) ° C to (Tg + 30) ° C, more preferably (Tg-30) ° C to (Tg + 20) ° C, and more preferably (Tg-15) ° C to (Tg + 10) ° C for 1 second to 10 minutes. More preferably 5 seconds to 4 minutes, still more preferably 10 seconds to 2 minutes, 0.1 kg / m to 20 kg / m, more preferably 1 kg / m to 16 kg / m, still more preferably 2 kg / m to 12 kg / m. It is preferable to carry out while conveying with tension.

[Polarizer]
The polarizing plate of the present invention can be obtained by laminating at least a polarizer (hereinafter also referred to as a polarizing film) on the film of the present invention. Hereinafter, the polarizing plate of the present invention will be described. Examples of the polarizing plate of the present invention include a polarizing plate formed on the surface of a polarizing film for the purpose of two functions of a protective film and viewing angle compensation, and a composite polarizing plate laminated on a protective film such as TAC. Can be mentioned.

  If the polarizing plate of this invention uses the film and polarizer of this invention, there will be no restriction | limiting in particular in a structure. For example, when the polarizing plate of the present invention is composed of a polarizer and two polarizing plate protective films (transparent polymer films) that protect both sides of the polarizer, the film of the present invention may be used as at least one polarizing plate protective film. it can. Moreover, the polarizing plate of this invention may have an adhesive layer for sticking with another member in the at least one surface. Moreover, in the polarizing plate of this invention, if the surface of the film of this invention is an uneven | corrugated structure, it will have an anti-glare (anti-glare) function. Further, the polarizing plate of the present invention has an antireflection film of the present invention in which an antireflection layer (low refractive index layer) is further laminated on the surface of the film of the present invention, and further optical anisotropy on the surface of the film of the present invention. It is also preferable to use the optical compensation film of the present invention in which layers are laminated.

  In general, a liquid crystal display device includes four polarizing plate protective films because a liquid crystal cell is provided between two polarizing plates. The film of the present invention may be used for any of the four polarizing plate protective films, but the film of the present invention is particularly advantageous as a protective film disposed between a liquid crystal cell and a polarizing plate in a liquid crystal display device. Can be used.

  The polarizing plate of the present invention more preferably has a configuration in which a cellulose acylate film, a polarizer and a film of the present invention are laminated in this order. Moreover, the structure which the cellulose acylate film, the polarizer, the film of this invention, and the adhesive layer are laminated | stacked in this order is also more preferable.

(Optical film)
The film of the present invention is used for the optical film of the polarizing plate of the present invention. The film can be surface treated. Examples of the surface treatment method include methods such as corona discharge, glow discharge, UV irradiation, and flame treatment.

(Cellulose acylate film)
As the cellulose acylate film of the polarizing plate of the present invention, a known cellulose acylate film for a polarizing plate is used. For example, a known triacetyl cellulose (TAC) film (for example, Fujitac T-60 manufactured by Fuji Film Co., Ltd.) can be preferably used. The lurose acylate film may be surface treated. Examples of the surface treatment method include saponification treatment.

(Polarizer)
As the polarizer, for example, a film obtained by immersing and stretching a polyvinyl alcohol film in an iodine solution can be used.

  As the polarizer used in the present invention, any appropriate one can be selected as long as the object of the present invention can be achieved. Examples of the polarizer include a uniaxially stretched film obtained by adsorbing a dichroic substance such as iodine or a dichroic dye on a hydrophilic polymer film, a dehydrated polyvinyl alcohol product or a dehydrochlorinated polyvinyl chloride product. And polyene-based oriented films. Examples of the hydrophilic polymer film include a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, and an ethylene / vinyl acetate copolymer partially saponified film. In the present invention, a polarizer in which iodine is adsorbed on a polyvinyl alcohol film is preferable.

  The polarizer preferably further contains at least one of potassium and boron. When the polarizer contains potassium and boron, a polarizer (polarizing plate) having a composite elastic modulus (Er) in a preferable range and having a high degree of polarization can be obtained. For production of a polarizer containing at least one of potassium and boron, for example, a film which is a material for forming a polarizer may be immersed in a solution of at least one of potassium and boron. The solution may also serve as a solution containing iodine.

  Any appropriate molding method can be adopted as a method for obtaining the polyvinyl alcohol film. A conventionally known method can be applied as the molding method. Moreover, a commercially available film can be used as it is for the polyvinyl alcohol film. Examples of commercially available polyvinyl alcohol films include the product name “Kuraray Vinylon Film” manufactured by Kuraray Co., Ltd., the product name “Tosero Vinylon Film” manufactured by Tosero Co., Ltd., and the product manufactured by Nippon Synthetic Chemical Industry Co., Ltd. Names include “Nippon Vinylon Film”.

  Regarding an example of a method for producing a polarizer, for example, a polymer film (raw film) mainly composed of a polyvinyl alcohol resin is immersed in a swelling bath containing pure water and a dyeing bath containing an aqueous iodine solution. Swelling treatment and dyeing treatment are performed while applying tension in the film longitudinal direction with different rolls. Next, the film subjected to the swelling treatment and the dyeing treatment is immersed in a crosslinking bath containing potassium iodide, and is subjected to crosslinking treatment and final stretching treatment while tension is applied in the longitudinal direction of the film with rolls having different speed ratios. Is given. The film subjected to crosslinking treatment is immersed in a washing bath containing pure water by a roll and subjected to a washing treatment. The film subjected to the water washing treatment is dried and wound up after adjusting the moisture content. Thus, the polarizer can be obtained by stretching the original film, for example, 5 to 7 times the original length.

  The polarizer may be subjected to any surface modification treatment in order to improve the adhesion with the adhesive. Examples of the surface modification treatment include corona treatment, plasma treatment, glow discharge treatment, flame treatment, ozone treatment, UV ozone treatment, and ultraviolet treatment. These treatments may be used alone or in combination of two or more.

(Adhesive layer)
The polarizing plate of the present invention may have an adhesive layer as at least one of the outermost layers (such a polarizing plate may be referred to as an adhesive polarizing plate). As a particularly preferred embodiment, a pressure-sensitive adhesive layer for adhering to other members such as other films and liquid crystal cells can be provided on the side of the film where the polarizer is not adhered.

(Production method of polarizing plate)
The manufacturing method of the polarizing plate of this invention is demonstrated.
The polarizing plate of the present invention can be produced by bonding one side of the film of the present invention (a surface-treated surface in the case of surface treatment) to at least one side of the polarizer using an adhesive. When the cellulose acylate film, the polarizer and the film of the present invention are bonded together in this order, the polarizing plate of the present invention can be produced by laminating the polarizer and other films using an adhesive on both sides of the polarizer. .
In the manufacturing method of the polarizing plate of this invention, it is preferable that the film of this invention is directly bonded with the polarizer.

  As the adhesive, a known polarizing plate production adhesive can be used. Moreover, the aspect which has an adhesive bond layer between the said polarizer and each film is also preferable. Specific examples of the adhesive include an aqueous solution of polyvinyl alcohol or polyvinyl acetal (eg, polyvinyl butyral) and a latex of a vinyl-based polymer (eg, polybutyl acrylate). A particularly preferred adhesive is an aqueous solution of fully saponified polyvinyl alcohol. The polyvinyl alcohol-based adhesive preferably contains a polyvinyl alcohol-based resin and a crosslinking agent.

  The manufacturing method of the polarizing plate of this invention is not limited to said method, Another method can also be used. For example, JP 2000-171635, JP 2003-215563, JP 2004-70296, JP 2005-189437, JP 2006-199788, JP 2006-215463, JP 2006-227090. JP, 2006-243216, JP 2006-243681, JP 2006-259313, JP 2006-276574, JP 2006-316181, JP 2007-10756, JP 2007-128025, Use methods described in JP 2007-140092, JP 2007-171943, JP 2007-197703, JP 2007-316366, JP 2007-334307, JP 2008-20891, etc. it can. Among these, the methods described in JP2007-316366A and JP2008-20891A are more preferable.

  It is preferable that a protective film is also attached to the other surface of the polarizing film, and the protective film may be the film of the present invention. Moreover, the various films conventionally used as a protective film of a polarizing plate, such as a cellulose acylate film and a cyclic polyolefin polymer film, can be used.

  The polarizing plate of the present invention thus obtained is preferably used in a liquid crystal display device, and may be provided on either the viewing side or the backlight side of the liquid crystal cell, or on both sides. Not. Specific examples of the image display device to which the polarizing plate of the present invention can be applied include a self-luminous display device such as an electroluminescence (EL) display, a plasma display (PD), and a field emission display (FED: Field Emission Display). Can be mentioned. The liquid crystal display device is applied to a transmissive liquid crystal display device, a reflective liquid crystal display device, and the like.

[Liquid Crystal Display]
The film and polarizing plate of the present invention can be used for liquid crystal display devices of various modes. Preferably, it can be used for TN (Twisted Nematic), OCB (Optically Compensatory Bend), ECB (Electrically Controlled Birefringence) mode liquid crystal display devices, and more preferably for TN and ECB mode liquid crystal displays.

[Optical compensation film]
The film of the present invention can be preferably used as a film for optical applications, and can be particularly preferably used as an optical compensation film.

<Laminated film>
It can also be set as a laminated | multilayer film by further providing an optically anisotropic layer to the film of this invention. Below, the structure of the optical compensation film at the time of setting it as a laminated film is demonstrated.

(Optically anisotropic layer)
The optically anisotropic layer is preferably designed so as to compensate for the liquid crystalline compound in the liquid crystal cell in the black display of the liquid crystal display device. The alignment state of the liquid crystal compound in the liquid crystal cell in black display varies depending on the mode of the liquid crystal display device. The alignment state of the liquid crystal compound in this liquid crystal cell is described in IDW'00, P411 to 414 of FMC7-2, and the like.
The optically anisotropic layer is formed directly from the liquid crystalline compound on the support or from the liquid crystalline compound via an alignment film. The alignment film preferably has a thickness of 10 μm or less.
The liquid crystalline compound used for the optically anisotropic layer includes a rod-like liquid crystalline compound and a discotic liquid crystalline compound. The rod-like liquid crystal compound and the discotic liquid crystal compound may be a high-molecular liquid crystal or a low-molecular liquid crystal, and further include those in which the low-molecular liquid crystal is cross-linked and no longer exhibits liquid crystallinity. The optically anisotropic layer can be formed by applying a liquid crystal compound and, if necessary, a coating liquid containing a polymerizable initiator and optional components on the alignment film. A preferred example of the alignment film of the present invention is described in JP-A-8-338913.

(Bar-shaped liquid crystalline compound)
Examples of rod-like liquid crystalline compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines. , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.
The rod-like liquid crystalline compound includes a metal complex. Moreover, the liquid crystal polymer which contains a rod-shaped liquid crystalline compound in a repeating unit can also be used as a rod-shaped liquid crystalline compound. That is, the rod-like liquid crystalline compound may be bonded to a (liquid crystal) polymer.
Regarding rod-like liquid crystalline compounds, for example, Quarterly Chemical Review Vol. 22, Liquid Crystal Chemistry (1994), Chapter 4, Chapter 7 and Chapter 11 of the Chemical Society of Japan, and Liquid Crystal Device Handbook, Japan Society for the Promotion of Science, 142nd Committee The one described in Chapter 3 of the edition can be adopted.
The birefringence of the rod-like liquid crystalline compound is preferably in the range of 0.001 to 0.7.

  The rod-like liquid crystalline compound preferably has a polymerizable group in order to fix its alignment state. The polymerizable group is preferably an unsaturated polymerizable group or an epoxy group, more preferably an unsaturated polymerizable group, and most preferably an ethylenically unsaturated polymerizable group.

(Discotic liquid crystalline compounds)
Examples of discotic liquid crystalline compounds include C.I. Benzene derivatives described in a research report of Destrade et al. (Mol. Cryst. 71, 111 (1981)), C.I. Destrode et al. (Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990)) described in The cyclohexane derivatives described in the research report of Kohne et al. (Angew. Chem. 96, 70 (1984)) and M.M. Lehn et al. (JCS, Chem. Commun., 1794 (1985)), J.C. Azacrown-type and phenylacetylene-type macrocycles described in the research report of Zhang et al. (J. Am. Chem. Soc. 116, 2655 (1994)) are included.

  The discotic liquid crystalline compound also includes a compound having a structure in which a linear alkyl group, an alkoxy group, and a substituted benzoyloxy group are radially substituted as a side chain of the mother nucleus with respect to the mother nucleus at the center of the molecule. The molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting a certain orientation. The optically anisotropic layer formed from the discotic liquid crystalline compound does not necessarily require that the compound finally contained in the optically anisotropic layer is a discotic liquid crystalline compound. Also included are compounds having a group that reacts with heat or light and, as a result, polymerized or cross-linked by reaction with heat or light, resulting in a high molecular weight and loss of liquid crystallinity. Preferred examples of the discotic liquid crystalline compound are described in JP-A-8-50206. Moreover, about superposition | polymerization of a discotic liquid crystalline compound, Unexamined-Japanese-Patent No. 8-27284 has description.

  In order to fix the discotic liquid crystalline compound by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline compound. However, when the polymerizable group is directly connected to the disc-shaped core, it becomes difficult to maintain the orientation state in the polymerization reaction. Therefore, a linking group is introduced between the discotic core and the polymerizable group. Therefore, the discotic liquid crystalline compound having a polymerizable group is preferably a compound represented by the following formula (5).

General formula (5)
D (-LQ) _r
(In General Formula (5), D is a discotic core, L is a divalent linking group, Q is a polymerizable group, and r is an integer of 4 to 12.)

  An example of the disk-shaped core (D) is shown below. In each of the following examples, LQ (or QL) means a combination of a divalent linking group (L) and a polymerizable group (Q).

  In the general formula (5), the divalent linking group (L) is selected from the group consisting of an alkylene group, an alkenylene group, an arylene group, —CO—, —NH—, —O—, —S—, and combinations thereof. It is preferable that it is a bivalent coupling group. The divalent linking group (L) is a divalent combination of at least two divalent groups selected from the group consisting of an alkylene group, an arylene group, -CO-, -NH-, -O-, and -S-. More preferably, it is a linking group. The divalent linking group (L) is most preferably a divalent linking group in which at least two divalent groups selected from the group consisting of an alkylene group, an arylene group, -CO- and -O- are combined. . The alkylene group preferably has 1 to 12 carbon atoms. The alkenylene group preferably has 2 to 12 carbon atoms. The number of carbon atoms in the arylene group is preferably 6-10.

Examples of the divalent linking group (L) are shown below. The left side is bonded to the discotic core (D), and the right side is bonded to the polymerizable group (Q). AL represents an alkylene group or an alkenylene group, and AR represents an arylene group. The alkylene group, alkenylene group and arylene group may have a substituent (eg, an alkyl group).
L1: -AL-CO-O-AL-,
L2: -AL-CO-O-AL-O-,
L3: -AL-CO-O-AL-O-AL-,
L4: -AL-CO-O-AL-O-CO-,
L5: -CO-AR-O-AL-,
L6: -CO-AR-O-AL-O-,
L7: -CO-AR-O-AL-O-CO-,
L8: -CO-NH-AL-,
L9: -NH-AL-O-,
L10: -NH-AL-O-CO-,

L11: -O-AL-,
L12: -O-AL-O-,
L13: -O-AL-O-CO-,
L14: -O-AL-O-CO-NH-AL-,
L15: -O-AL-S-AL-,
L16: -O-CO-AL-AR-O-AL-O-CO-,
L17: -O-CO-AR-O-AL-CO-,
L18: -O-CO-AR-O-AL-O-CO-,
L19: -O-CO-AR-O-AL-O-AL-O-CO-,
L20: -O-CO-AR-O-AL-O-AL-O-AL-O-CO-,
L21: -S-AL-,
L22: -S-AL-O-,
L23: -S-AL-O-CO-,
L24: -S-AL-S-AL-,
L25: -S-AR-AL-.

  The polymerizable group (Q) of the general formula (5) is determined according to the type of polymerization reaction. Examples of the polymerizable group (Q) are shown below.

  The polymerizable group (Q) is preferably an unsaturated polymerizable group (Q1, Q2, Q3, Q7, Q8, Q15, Q16, Q17) or an epoxy group (Q6, Q18). More preferably, it is most preferably an ethylenically unsaturated polymerizable group (Q1, Q7, Q8, Q15, Q16, Q17). A specific value of r is determined according to the type of the disk-shaped core (D). In addition, although the combination of several L and Q may differ, it is preferable that it is the same.

  In the hybrid alignment, the angle between the major axis (disk surface) of the discotic liquid crystalline compound and the surface of the support, that is, the inclination angle is in the direction of the depth of the optically anisotropic layer (that is, perpendicular to the transparent support). And it increases or decreases as the distance from the plane of the polarizing film increases. The angle preferably increases with increasing distance. Further, the change in the tilt angle can be continuous increase, continuous decrease, intermittent increase, intermittent decrease, change including continuous increase and continuous decrease, or intermittent change including increase and decrease. . The intermittent change includes a region where the inclination angle does not change in the middle of the thickness direction. Even if a region where the angle does not change is included, it may be increased or decreased as a whole. However, it is preferred that the tilt angle changes continuously.

The average direction of the major axis (disk surface) of the discotic liquid crystalline compound (average of the major axis direction of each molecule) is generally selected by selecting the discotic liquid crystalline compound or the material of the alignment film, or selecting the rubbing treatment method. By doing so, it can be adjusted. The major axis (disk surface) direction of the discotic liquid crystalline compound on the surface side (air side) is generally adjusted by selecting the type of additive used together with the discotic liquid crystalline compound or the discotic liquid crystalline compound. be able to.
Examples of the additive used together with the discotic liquid crystalline compound include a plasticizer, a surfactant, a polymerizable monomer and a polymer. The degree of change in the orientation direction of the major axis can also be adjusted by selecting liquid crystalline molecules and additives as described above.

  The plasticizer, surfactant and polymerizable monomer used together with the discotic liquid crystalline compound are compatible with the discotic liquid crystalline compound, and can change the tilt angle of the discotic liquid crystalline compound or change the orientation. It is preferable not to inhibit. Among the additive components, addition of a polymerizable monomer (eg, a compound having a vinyl group, a vinyloxy group, an acryloyl group and a methacryloyl group) is preferable. The amount of the compound added is generally in the range of 1 to 50% by mass and preferably in the range of 5 to 30% by mass with respect to the discotic liquid crystalline compound. In addition, when a monomer having 4 or more polymerizable reactive functional groups is mixed and used, adhesion between the alignment film and the optically anisotropic layer can be improved.

The optically anisotropic layer may contain a polymer together with the discotic liquid crystalline compound. The polymer preferably has a certain degree of compatibility with the discotic liquid crystalline compound and can change the tilt angle of the discotic liquid crystalline compound. A cellulose ester can be mentioned as an example of a polymer. Preferable examples of the cellulose ester include cellulose acetate, cellulose acetate propionate, hydroxypropyl cellulose and cellulose acetate butyrate. The addition amount of the polymer is preferably in the range of 0.1 to 10% by mass with respect to the discotic liquid crystalline compound so as not to inhibit the orientation of the discotic liquid crystalline compound, and 0.1 to 8% by mass. More preferably, it is in the range of 0.1 to 5% by mass.
The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline compound is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

(Fixing the alignment state of liquid crystalline molecules)
The aligned liquid crystal molecules can be fixed while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. A photopolymerization reaction is preferred.

(Photopolymerization initiator)
Examples of photopolymerization initiators include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ethers (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatic acyloin compounds ( US Pat. No. 2,722,512), polynuclear quinone compounds (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of triarylimidazole dimer and p-aminophenyl ketone (described in US Pat. No. 3,549,367), acridine, and Phenazine compounds (described in JP-A-60-105667 and US Pat. No. 4,239,850) and oxadiazole compounds (described in US Pat. No. 4,221,970) are included.

The amount of the photopolymerization initiator used is preferably in the range of 0.01 to 20% by mass, more preferably in the range of 0.5 to 5% by mass, based on the solid content of the coating solution.
It is preferable to use ultraviolet rays for light irradiation for polymerization of liquid crystalline molecules.
The irradiation energy is preferably in the range of ^{20mJ / cm 2 ~50J / cm 2} , more preferably in the range of ^{20mJ / cm 2 ~5000mJ / cm 2} , a range of 100mJ / cm ² ~800mJ / cm ² More preferably. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.
A protective layer may be provided on the optically anisotropic layer.

  The optically anisotropic layer is prepared by preparing a coating solution containing at least one of the liquid crystalline compounds and, optionally, an additive such as a polymerizable initiator and a fluorine-based polymer, and applying the coating solution to the alignment film surface. It can be formed by drying.

(Fluorine compounds)
Examples of the fluorine-based compound include conventionally known compounds. Specific examples include the fluorine-based compounds described in paragraphs [0028] to [0056] of JP-A-2001-330725. It is done.

(solvent)
As a solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of organic solvents include amides (eg, N, N-dimethylformamide), sulfoxides (eg, dimethyl sulfoxide), heterocyclic compounds (eg, pyridine), hydrocarbons (eg, benzene, hexane), alkyl halides (eg, , Chloroform, dichloromethane, tetrachloroethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.
When producing an optical compensation film with high uniformity, the surface tension of the coating solution is preferably 25 mN / m or less, and more preferably 22 mN / m or less.

(Method for producing optical compensation film)
The coating liquid can be applied by a known method (eg, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method).

Prior to the application of the liquid crystalline compound, it is preferable to rub the surface of the film to be applied. In the rubbing method, a rubbing treatment method widely adopted as a liquid crystal alignment treatment process of LCD can be applied. That is, orientation is obtained by rubbing the surface of the film in a certain direction using paper, gauze, felt, rubber, nylon, or polyester fiber. In general, it is carried out by rubbing several times using a cloth in which fibers having a uniform length and thickness are planted on average. It is preferable to carry out using a rubbing roll in which the roundness, cylindricity, and deflection (eccentricity) of the roll itself are all 30 μm or less. The film wrap angle on the rubbing roll is preferably 0.1 to 90 degrees. However, as described in JP-A-8-160430, a stable rubbing treatment can be obtained by winding 360 degrees or more.
When rubbing a long film, the film is preferably transported at a speed of 1 to 100 m / min in a constant tension state by a transport device. The rubbing roll is preferably rotatable in the horizontal direction with respect to the film traveling direction for setting an arbitrary rubbing angle. It is preferable to select an appropriate rubbing angle in the range of 0 to 60 degrees. When used in a liquid crystal display device, 40 to 50 degrees is preferable. 45 degrees is particularly preferable.

[Antireflection film]
The antireflection film of the present invention is obtained by providing an antireflection layer on the film of the present invention. The antireflection film generally includes a low refractive index layer which is also an antifouling layer, and at least one layer having a refractive index higher than that of the low refractive index layer (a high refractive index layer and a medium refractive index in the present specification). Layer) on a (transparent) support.

Colloidal metal is formed as a multilayer film in which transparent thin films of inorganic compounds (metal oxides, etc.) with different refractive indexes are laminated by chemical vapor deposition (CVD) method, physical vapor deposition (PVD) method, or metal compound sol-gel method such as metal alkoxide. Examples include a method of forming a thin film by post-processing (ultraviolet irradiation: JP-A-9-157855, plasma processing: JP-A-2002-327310) after forming an oxide particle film.
On the other hand, various antireflection films formed by laminating thin films in which inorganic particles are dispersed in a matrix have been proposed as antireflection films with high productivity.
The antireflection film which consists of the antireflection layer which provided the anti-glare property which the antireflection film by application | coating as mentioned above provided the surface of the uppermost layer with the shape of a fine unevenness | corrugation is also mentioned.
The film of the present invention can be applied to any of the above methods, but the coating method (coating type) is particularly preferable.

(Layer structure)
(Transparent) The antireflection film comprising a layer structure of at least a middle refractive index layer, a high refractive index layer, and a low refractive index layer (outermost layer) on the support has a refractive index satisfying the following relationship: Designed.
The refractive index of the high refractive index layer> The refractive index of the medium refractive index layer> The refractive index of the transparent support> The refractive index of the low refractive index layer Further, a hard coat layer is provided between the transparent support and the medium refractive index layer. May be. Furthermore, it may consist of a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer.
Examples thereof include JP-A-8-122504, JP-A-8-110401, JP-A-10-300902, JP-A-2002-243906, JP-A-2000-11706, and the like.

  Other functions may be imparted to each layer, for example, an antifouling low refractive index layer or an antistatic high refractive index layer (eg, JP-A-10-206603, JP-A-2002). -243906 publication etc.) etc. are mentioned.

  The haze of the antireflection film is preferably 5% or less, more preferably 3% or less. Further, the strength of the film is preferably H or more, more preferably 2H or more, and most preferably 3H or more in a pencil hardness test according to JIS K5400.

(High refractive index layer and medium refractive index layer)
The layer having a high refractive index of the antireflection film is composed of a curable film containing at least an inorganic compound ultrafine particle having a high refractive index having an average particle size of 100 nm or less and a matrix binder.
Examples of the high refractive index inorganic compound fine particles include inorganic compounds having a refractive index of 1.65 or more, preferably those having a refractive index of 1.9 or more. Examples thereof include oxides such as Ti, Zn, Sb, Sn, Zr, Ce, Ta, La, and In, and composite oxides containing these metal atoms.
In order to obtain such ultrafine particles, the surface of the particles is treated with a surface treatment agent (for example, silane coupling agents, etc .: JP-A-11-295503, JP-A-11-153703, JP-A-2000-9908). No., anionic compound or organometallic coupling agent: Japanese Patent Laid-Open No. 2001-310432, etc., core-shell structure with high refractive index particles as a core (Japanese Patent Laid-Open No. 2001-166104, etc.), specific dispersant Combined use (for example, Unexamined-Japanese-Patent No. 11-153703, patent number US62081058B1, Unexamined-Japanese-Patent No. 2002-27776069 etc.) etc. are mentioned.
Examples of the material forming the matrix include conventionally known thermoplastic resins and curable resin films.
Further, it is selected from a polyfunctional compound-containing composition containing at least two radically polymerizable and / or cationically polymerizable groups, an organometallic compound containing a hydrolyzable group, and a partial condensate composition thereof. At least one composition is preferred. Examples thereof include compounds described in JP-A Nos. 2000-47004, 2001-315242, 2001-31871, and 2001-296401.
A curable film obtained from a colloidal metal oxide obtained from a hydrolyzed condensate of metal alkoxide and a metal alkoxide composition is also preferred. For example, it describes in Unexamined-Japanese-Patent No. 2001-293818.
The refractive index of the high refractive index layer is generally 1.70 to 2.20. The thickness of the high refractive index layer is preferably 5 nm to 10 μm, and more preferably 10 nm to 1 μm.
The refractive index of the middle refractive index layer is adjusted to be a value between the refractive index of the low refractive index layer and the refractive index of the high refractive index layer. The refractive index of the middle refractive index layer is preferably 1.50 to 1.70.

(Low refractive index layer)
The low refractive index layer is formed by sequentially laminating on the high refractive index layer. The refractive index of the low refractive index layer is 1.20 to 1.55. Preferably it is 1.30-1.50.
It is preferable to construct as the outermost layer having scratch resistance and antifouling property. As means for greatly improving the scratch resistance, imparting slipperiness to the surface is effective, and conventionally known thin film layer means such as introduction of silicone or introduction of fluorine can be applied.
The refractive index of the fluorine-containing compound is preferably 1.35 to 1.50. More preferably, it is 1.36-1.47. The fluorine-containing compound is preferably a compound containing a crosslinkable or polymerizable functional group containing fluorine atoms in the range of 35 to 80% by mass.
For example, paragraph numbers [0018] to [0026] of Japanese Patent Application Laid-Open No. 9-222503, paragraph numbers [0019] to [0030] of Japanese Patent Application Laid-Open No. 11-38202, and paragraph numbers of Japanese Patent Application Laid-Open No. 2001-40284. [0027] to [0028], JP-A 2000-284102, and the like.
The silicone compound is a compound having a polysiloxane structure, preferably containing a curable functional group or a polymerizable functional group in the polymer chain and having a crosslinked structure in the film. For example, reactive silicone (eg, Silaplane (manufactured by Chisso Corporation), silanol group-containing polysiloxane (Japanese Patent Laid-Open No. 11-258403, etc.) and the like can be mentioned.

The crosslinking or polymerization reaction of the fluorine-containing and / or siloxane polymer having a crosslinking or polymerizable group is carried out at the same time or after the coating composition for forming the outermost layer containing a polymerization initiator, a sensitizer, etc. It is preferable to carry out by light irradiation or heating.
Also preferred is a sol-gel cured film in which an organometallic compound such as a silane coupling agent and a specific fluorine-containing hydrocarbon group-containing silane coupling agent are cured by a condensation reaction in the presence of a catalyst.

  For example, a polyfluoroalkyl group-containing silane compound or a partially hydrolyzed condensate thereof (Japanese Patent Laid-Open Nos. 58-142958, 58-147483, 58-147484, Japanese Patent Laid-Open Nos. 9-157582, 11) -106704), silyl compounds containing a poly "perfluoroalkyl ether" group which is a fluorine-containing long chain group (Japanese Patent Application Laid-Open Nos. 2000-117902, 2001-48590, 2002) 53804), and the like.

The low refractive index layer has an average primary particle diameter of 1 to 150 nm such as a filler (for example, silicon dioxide (silica), fluorine-containing particles (magnesium fluoride, calcium fluoride, barium fluoride)) as an additive other than the above. Low refractive index inorganic compounds, organic fine particles described in paragraphs [0020] to [0038] of JP-A-11-3820, etc.), silane coupling agents, slip agents, surfactants, and the like can be contained.
When the low refractive index layer is located below the outermost layer, the low refractive index layer may be formed by a vapor phase method (vacuum deposition method, sputtering method, ion plating method, plasma CVD method, etc.). The coating method is preferable because it can be manufactured at a low cost.
The film thickness of the low refractive index layer is preferably 30 to 200 nm, more preferably 50 to 150 nm, and most preferably 60 to 120 nm.

(Hard coat layer)
The hard coat layer is provided on the surface of the transparent support in order to impart physical strength to the antireflection film. In particular, it is preferably provided between the transparent support and the high refractive index layer.
The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of a light and / or heat curable compound.
The curable functional group is preferably a photopolymerizable functional group, and the hydrolyzable functional group-containing organometallic compound is preferably an organic alkoxysilyl compound.
Specific examples of these compounds are the same as those exemplified for the high refractive index layer.
Specific examples of the constituent composition of the hard coat layer include those described in JP-A Nos. 2002-144913, 2000-9908, and WO 00/46617.
The high refractive index layer can also serve as a hard coat layer. In such a case, it is preferable to form fine particles dispersed in the hard coat layer using the method described for the high refractive index layer.

The hard coat layer can also serve as an antiglare layer (described later) provided with particles having an average particle size of 0.2 to 10 μm to provide an antiglare function (antiglare function).
The film thickness of the hard coat layer can be appropriately designed depending on the application. The film thickness of the hard coat layer is preferably 0.2 to 10 μm, more preferably 0.5 to 7 μm.
The strength of the hard coat layer is preferably H or higher, more preferably 2H or higher, and most preferably 3H or higher in a pencil hardness test according to JIS K5400. Further, in the Taber test according to JIS K5400, the smaller the wear amount of the test piece before and after the test, the better.

(Forward scattering layer)
The forward scattering layer is provided in order to give a viewing angle improvement effect when the viewing angle is inclined in the vertical and horizontal directions when applied to a liquid crystal display device. By dispersing fine particles having different refractive indexes in the hard coat layer, it can also serve as a hard coat function.
For example, Japanese Patent Laid-Open No. 11-38208 specifying a forward scattering coefficient, Japanese Patent Laid-Open No. 2000-199809 having a relative refractive index of a transparent resin and fine particles in a specific range, and Japanese Patent Laid-Open No. 2002 specifying a haze value of 40% or more. -107512 gazette etc. are mentioned.

(Other layers)
In addition to the above layers, a primer layer, an antistatic layer, an undercoat layer, a protective layer, and the like may be provided.

(Production method of antireflection film)
Each layer of the antireflection film is formed by a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating, a micro gravure method or an extrusion coating method (US Pat. No. 2,681,294). It can be formed by coating.

  The antireflection film may have an antiglare function that scatters external light. The antiglare function is obtained by forming irregularities on the surface of the antireflection film. When the antireflection film has an antiglare function, the haze of the antireflection film is preferably 3 to 30%, more preferably 5 to 20%, and most preferably 7 to 20%.

  As a method for forming irregularities on the surface of the antireflection film, any method can be applied as long as these surface shapes can be sufficiently maintained. For example, a method of forming irregularities on the film surface using fine particles in the low refractive index layer (for example, JP 2000-271878 A), a lower layer of the low refractive index layer (high refractive index layer, medium refractive index layer) Alternatively, a small amount (0.1 to 50% by mass) of relatively large particles (particle size 0.05 to 2 μm) is added to the hard coat layer to form a surface uneven film, and these shapes are maintained thereon. A method of providing a low refractive index layer (for example, JP 2000-281410 A, JP 2000-95893 A, JP 2001-100004 A, 2001-281407, etc.), an uppermost layer (antifouling layer) A method of physically transferring the uneven shape onto the surface after coating (for example, as an embossing method, Japanese Patent Laid-Open Nos. 63-278839, 11-183710, 2000-275401) It includes equal forth) and the like.

The present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below. In addition, the following Examples 1, 4, 8 to 10 and 12 shall be read as Reference Examples 1, 4, 8 to 10 and 12, respectively.

<Measurement method>
(Re [0 °] variation measurement method)
The variation of Re [0 °] (ΔRe [0 °]) was measured according to the following method.
Sampling was performed at 10 points in the width direction of the film and 10 points in the conveyance direction at equal intervals, and using KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments), Re [0 °], Re [+ 40 °] and Re [−40 °] was measured, and the difference between the maximum value and the minimum value was regarded as the variation of Re [0 °], Re [+ 40 °], and Re [−40 °].

Production Example 1 Production of Cyclic Olefin Copolymer Pellets Pellets of “TOPAS # 6013” manufactured by Polyplastics were used as the cyclic olefin copolymer COC. “TOPAS # 6013” indicates positive intrinsic birefringence. The glass transition point of the resin was 136 ° C.

[Production Example 2] Production of cellulose acylate propionate pellets Cellulose acetate propionate (CAP) was produced according to the method described in Example 1 of JP-A-2006-348123, and pelletized according to a conventional method. did. The composition of the CAP used is a positive intrinsic birefringence with an acetylation degree of 0.15, a propionylation degree of 2.60, a total acyl substitution degree of 2.75, and a number average polymerization degree of DPn = 118. The glass transition point of the resin was 137 ° C.

[Production Example 3] Manufacture of pellets of polycarbonate PC As the polycarbonate, pellets of "Taflon MD1500" manufactured by Idemitsu Kosan Co., Ltd. were used. “Taflon MD1500” exhibits positive intrinsic birefringence. Moreover, the glass transition point of the said resin was 150 degreeC.

[Production Example 4] Production of styrene copolymer pellets As a styrene-maleic anhydride resin, pellets of "Daylark D332" manufactured by Nova Chemical Co. were used. “Daylark D332” indicates negative intrinsic birefringence. The glass transition point of the resin was 130 ° C.

[Example 1]
(Production of film)
The pellets of cyclic olefin copolymer TOPAS # 6013 were dried at 100 ° C. for 2 hours or more, melted at 260 ° C., kneaded and extruded using a single-screw kneading extruder. At this time, a screen filter, a gear pump, and a leaf disk filter were arranged in this order between the extruder and the die, and these were connected by a melt pipe. This was extruded from the die at the extrusion temperatures listed in Table 1.
Thereafter, a melt (molten resin) was extruded onto the cast roll. The film width of the melt at this time was 330 mm, the touch roll width was 220 mm, and the chill roll width was 1800 mm. That is, 55 mm at one end of the melt was a non-contact length. In addition, the touch roll used was crowned in consideration of roll deflection (3 μm in this example). At this time, the cylinder was set to 2.5 KN so that the pressure applied to the center of the film was 20 MPa, and the touch roll was brought into contact. In addition, it was confirmed by measuring the pressure through a prescale for medium pressure (manufactured by Fuji Film Co., Ltd.) between two rolls before extruding the melt at the cylinder set value.
Using these rolls, the touch roll speed, the chill roll speed, and the peripheral speed ratio were set to the conditions shown in Table 1 below to form a film. The temperature of the touch roll and chill roll was set to Tg-5 ° C., and the distance between the die and the melt landing point was set to 200 mm. The film forming atmosphere was 25 ° C. and 60%.
In addition, it is visually confirmed that the center of the film is securely in contact with the touch roll and chill roll, and the theoretically weighted pressure is being applied to the center of the film. It was confirmed by the fact that it was in the form of a plane.
Then, after trimming both ends (5 cm each of the full width) immediately before winding, thicknessing (knurling) with a width of 10 mm and a height of 20 μm was applied to both ends. The film was wound up 3000 m at a film forming speed of 5 m / min. The thickness of the film after film formation was 100 μm, and the film of Example 1 was produced.

(Optical properties of the film)
The optical properties of the obtained film of Example 1 are shown in Table 1. In addition, the inclination direction which measured Re [+40 degree] and Re [-40 degree] of the film of this invention is all the longitudinal direction of a film.

[Examples 2-14, Comparative Examples 1-4]
Except that the resin used and the film forming conditions were changed as described in Table 1 below, films of Examples and Comparative Examples were obtained in the same manner as Example 1. The optical properties of the films of the examples and comparative examples are shown in Table 1 below. In Comparative Example 4, a film was produced under the same conditions as in Example 1 of JP-A-2005-172940.

From Table 1, it was found that in Examples 1 to 14, all of the inclined structures having favorable phase differences were formed, and the variation in Re [0 °] was small. On the other hand, in Comparative Example 1, the roll non-contact length at the film edge is 45 mm, and the central roll pressure in the film width direction is 4 MPa. The obtained film has a small retardation structure and is not suitable as a retardation film. The performance was sufficient, and the variation in Re [0 °] was very large. That is, when the non-contact length is less than 50 mm, it is found that when the film is formed with a pinching device, the melt is thick at the film end and the pressure on the central portion is reduced, so that the phase difference is difficult to develop. . This is supported by the fact that in Comparative Example 1, the pressure applied to the end of the roll is much larger than that at the center. Furthermore, in Comparative Example 2, the roll non-contact length was set to 0 mm, the gradient structure of the retardation of the film obtained from Comparative Example 1 was further smaller, and the variation in Re [0 °] was further larger. . That is, in the conventional manufacturing method in which the non-contact length is 0 mm, when the film is formed with a pinching device, the melt becomes thick at the film edge, and the pressure to the central portion is reduced, so that the phase difference is hardly expressed. I found out. This is supported by the fact that the pressure applied to the end of the roll in Comparative Example 2 is larger than that in Comparative Example 1 compared to the central part. In Comparative Example 3, the roll non-contact length at the end of the film was set to 525 nm, a press-bonding failure to the roll occurred, and film formation could not be performed. In Comparative Example 4 in which a film was produced under the same conditions as in Example 1 of JP-A-2005-172940, the roll non-contact length at the film end and the central roll pressure in the film width direction deviated from the scope of the production method of the present invention. In addition, since there is no difference in the moving speed between the first clamping surface and the second clamping surface of the clamping device, the gradient structure of the retardation of the obtained film was small and the performance as a retardation film was insufficient.
As described above, according to the manufacturing method of the present invention, by adjusting the roll width, a high pressure can be uniformly applied to the melt in the width direction, and the tilt structure with good retardation and the variation in optical characteristics can be reduced. all right.

(Preparation of polarizing plate)
A polarizing plate was produced using the produced film of Example 1 and the film of Comparative Example 1. Specifically, first, iodine was adsorbed to a stretched polyvinyl alcohol film to prepare a polarizing film. Using this polarizing film, a Re = 270 nm λ / 2 plate composed of an 80 μm TAC film (manufactured by Fuji Film Co., Ltd.) and a uniaxially stretched norbornene polymer film in the arrangement shown in FIG. 1, Invention 1 Or the film of the comparative example 1 was bonded together. In this manner, two polarizing plates PL1 using the film of Example 1 and two PL2 using the film of Comparative Example 1 were produced.

(Production and evaluation of transflective ECB mode liquid crystal display)
Next, an ECB type transflective liquid crystal display device was manufactured using the polarizing plate. The liquid crystal cell used uses ZLI-1695 (manufactured by Merck) as the liquid crystal material, and the liquid crystal layer thickness is 2.4 μm in the reflective electrode region (reflective display portion) and 4.9 μm in the transmissive electrode region (transmissive display portion). did. The pretilt angle at the substrate interface of the liquid crystal layer was 2 degrees, and Δnd of the liquid crystal cell was about 150 nm for the reflective display portion and about 320 nm for the transmissive display portion.
The two types of polarizing plates prepared above were arranged above and below the liquid crystal cell as shown in FIG. The arrows in the polarizing plates P1 and P2 indicate the respective absorption axes, the arrows in the retardation film indicate the respective slow axes, and the arrows of the ECB cells indicate the rubbing direction of the rubbing treatment applied to the respective facing surfaces. Here, the 12 o'clock direction is 0 ° and the clockwise direction is +.

With respect to the liquid crystal display device LCD1 which is an embodiment of the present invention, a viewing angle with a contrast ratio of 10 or more in monochrome display was obtained. On the other hand, in the LCD 2 using the film of the comparative example, the viewing angle with a contrast ratio of 10 or more was less than 260 ° in any of the upper, lower, left and right directions.
Thus, when the film of the present invention is used, a large viewing angle compensation can be performed when incorporated in a liquid crystal display device.

(Antireflection film for liquid crystal display)
When the optical film of Example 1 was produced as a low reflection film according to Example 47 of the Japan Institute of Invention and Technology (Publication No. 2001-1745) and incorporated in a liquid crystal display device, good optical performance was obtained.

(Anti-reflection film for organic EL)
According to Japanese Patent Laid-Open No. 9-127885, the optical film of Example 1 and a linearly polarizing plate were bonded to each other so that the angle between the slow axis and the absorption axis was 45 degrees to prepare an antireflection film. The antireflection film was incorporated into an organic EL display device, and the antireflection function was confirmed. Furthermore, it confirmed that it had the asymmetric viewing angle performance from the characteristic of the film of this invention.

It is a top view showing the absorption axis of the polarizing plate, the orientation direction of a liquid crystal cell, and the slow axis of a film in the transflective ECB mode liquid crystal display device of the present invention.

Claims (8)

A step of melt-extruding a composition containing a thermoplastic resin from a die, and a film-like product by continuously pressing the melt-extruded melt between a first clamping surface and a second clamping surface constituting a clamping device In a method for producing a film comprising a step of forming into a melt,
Apply a pressure of 25 to 200 MPa to the central part in the width direction of the film-like melt by the clamping device,
Clamping a portion of 50 to 500 mm from at least one end of the film-like melt without bringing it into contact with at least one of the first clamping surface and the second clamping surface of the clamping device,
And the moving speed of said 1st pressing surface is made faster than the moving speed of said 2nd pressing surface, The manufacturing method of the film characterized by the above-mentioned. In the step of continuously pressing the melt-extruded melt between the first clamping surface and the second clamping surface constituting the clamping device to form a film, the clamping devices have different peripheral speeds. The method for producing a film according to claim 1, wherein there are two rolls. 3. The method for producing a film according to claim 1, wherein a portion of 50 to 500 mm from both ends of the film-like melt is placed on at least one of the first clamping surface and the second clamping surface of the clamping device. A method for producing a film, wherein the film is pressed without contacting the surface. In the manufacturing method of the film as described in any one of Claims 1-3, the part of 50-500 mm from the said edge part is only to one surface of the 1st clamping surface of the said clamping device, and a 2nd clamping surface. A method for producing a film, wherein the film is brought into contact and pinched. 5. The moving speed ratio between the first clamping surface and the second clamping surface of the clamping device defined by the following formula (I) is 0.70 to 0.99, 5. The method for producing a film according to one item.
Movement speed ratio = speed of the second clamping surface / speed of the first clamping surface (I) The method for producing a film according to any one of claims 2 to 5, wherein the roll not in contact with the melt is a touch roll. The film manufacturing method according to claim 2, wherein the contact portion of the roll is crowned. The thermoplastic resin is at least one selected from a cyclic olefin resin, a cellulose acylate resin, a polycarbonate resin, a styrene resin, and an acrylic resin. 2. A method for producing a film according to item 1.

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