JP2010069703A - Film, method for producing the film and apparatus for producing the film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film in which a sufficient optical compensation is achieved when used for a liquid crystal display, nonuniformity of a phase difference is small, and peelability is good, and a method for producing the same. <P>SOLUTION: The method for producing the film includes a process to pass a composition containing a thermoplastic resin between a first pinching surface and a second pinching surface which comprises a pinching device to continuously mold the composition in film-like. The composition is pinched by pressure of 20-1,000 MPa with the first pinching surface and the second pinching surface, temperature of the composition to be passed between the first pinching surface and the second pinching surface is Tg+5°C or higher, and at least one surface of the first pinching surface and the second pinching surface is controlled to have both at least one of a temperature range portion which is Tg or higher and at least one of a temperature range portion which is lower than Tg (wherein, Tg represents a glass transition temperature of the thermoplastic resin). <P>COPYRIGHT: (C)2010,JPO&INPIT

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 and a film production apparatus suitable for the film production method.

  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. Therefore, Patent Documents 2 and 3 describe that the above problem can be solved by applying a shearing force to the melt.

  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, ECB liquid crystal display, or transflective ECB liquid crystal display, the optical axis is inclined more than the above film, and the optical characteristics are more uniform. An optical film was desired.

On the other hand, in recent years, a method for improving the physical properties of a film obtained by controlling the temperature of the clamping device in a film production method using the clamping device has been disclosed. For example, in Patent Document 4, the temperature of the portion conveyed by the touch belt is Tg−60 to Tg + 20 ° C. and the temperature of the portion peeled off from the touch belt is Tg−30 using a pinching device including a cast roll and a touch belt. It is disclosed that the phase difference can be reduced and the optical axis inclination can be reduced by controlling the temperature so that the temperature becomes ~ Tg ° C. Patent Document 5 discloses that the roll temperature of the portion where the molten resin from the die comes into contact with the cooling roll and the roll temperature of the portion where the resin is separated from the cooling roll are controlled. It is disclosed that the crystallinity of the resin can be controlled.
JP-A-6-222213 JP 2003-25414 A JP 2007-38646 A JP 2007-237495 A JP 2006-256159 A

  In the film forming methods described in Patent Documents 2 and 3, the inventor has a large phase difference, particularly when a film passing between two rolls is formed at a pressure higher than that of the prior art by 20 MPa or more. It has been found that a film having an inclined structure can be produced. However, in order to create a film having a large inclined structure, it is necessary to increase the molding temperature. For this reason, if the extrusion temperature is increased or the two roll temperatures are increased, a large inclined structure is expressed. A new problem has been discovered that stripping dan is likely to occur.

  The present invention has been made in consideration of the above-mentioned problems, and a first object of the present invention is to realize sufficient optical compensation when used in a liquid crystal display, with small phase difference unevenness, and stripping. It is to provide a film having good properties and a method for producing the film. The second object of the present invention is to provide a film production apparatus suitable for the film production method.

  Therefore, as a result of further intensive studies by the inventor, as a result of applying a high pressure to the film-like melt, the temperature at the location where shear deformation is applied, and the location where the film is peeled off from at least one clamping surface of the clamping device It has been found that the above new problem can be solved by controlling the temperature of the pinching surface. Controlling the temperature at the place where a high pressure is applied to the film-like melt and the temperature at the place where the film-like melt is peeled off from the pinching device is based on the contents disclosed in Patent Document 5. It is not suggested, and the effects obtained are also different.

  Furthermore, when forming a film at a high pressure as in the production method of the present invention, contrary to the technical idea disclosed in Patent Document 4, there is a surprising effect that the retardation of the obtained film is further improved. I found out.

  As a result of intensive studies to solve the above problems, the present inventors have found that the following production method and a film produced by the method can solve the above problems, and have completed the present invention described below.

[1] In a film manufacturing method including a step of continuously forming a film containing a thermoplastic resin-containing composition between a first clamping surface and a second clamping surface constituting a narrow pressure device, The composition is narrowed at a pressure of 20 to 1000 MPa by the first clamping surface and the second clamping surface, and the temperature of the composition passing between the first clamping surface and the second clamping surface is Tg + 5 ° C. or higher. And at least one of the first clamping surface and the second clamping surface is controlled so as to have at least one temperature region portion equal to or higher than Tg and one temperature region portion lower than Tg. Film production method (however, Tg represents the glass transition temperature of the thermoplastic resin).
[2] The surfaces of both the first clamping surface and the second clamping surface are controlled to have at least one temperature region portion equal to or higher than Tg and one temperature region portion lower than Tg. The method for producing a film according to 1].
[3] The temperature T1 of at least one clamping surface in a portion 1 cm above the clamping surface from a position where the composition is narrowed is Tg or more, according to [1] or [2] Film production method (however, Tg represents the glass transition temperature of the thermoplastic resin).
[4] Temperature T2 at a portion 1 cm below the pressure-clamping surface from the portion where the composition is narrowed in the pressure-clamping surface of the first pressure-clamping surface and the second pressure-clamping surface that is peeled off first from the film-like composition. Is less than Tg, The manufacturing method of the film as described in any one of [1]-[3] (however, Tg represents the glass transition temperature of the said thermoplastic resin).
[5] The method for producing a film according to any one of [1] to [4], wherein the narrow pressure device is at least two rolls.
[6] The method for producing a film according to any one of [1] to [5], wherein the narrow pressure device is at least one roll and a belt.
[7] The method for producing a film according to any one of [1] to [6], wherein T1 is Tg + 15 ° C. or more (where Tg is a glass transition temperature of the thermoplastic resin). Represents.)
[8] The method for producing a film according to any one of [1] to [7], wherein T2 is Tg−5 ° C. or less (where Tg is a glass transition temperature of the thermoplastic resin). Represents.)
[9] The method for producing a film according to any one of [1] to [8], wherein the difference between the T1 and T2 is 5 to 100 ° C.
[10] The length from the portion where the thermoplastic resin-containing composition is clamped by the clamping device to the portion where the thermoplastic resin-containing composition is peeled off from the clamping device is 0.1 mm or more and less than 200 mm [1] ] The manufacturing method of the film as described in any one of [9].
[11] A film produced by the method for producing a film according to any one of [1] to [10].
[12] A film manufacturing apparatus including a narrowing device having a first clamping surface and a second clamping surface, wherein the first clamping surface and the second clamping surface are the first clamping surface and the second clamping surface. It is arranged so that a composition containing a thermoplastic resin can be continuously passed between the pressing surfaces at a pressure of 20 to 1000 MPa while being narrowed, and at least of the first pressing surface and the second pressing surface The temperature of the composition in which any one of the surfaces has at least one temperature region portion equal to or higher than Tg and a temperature region portion lower than Tg, and is compressed between the first pressure-clamping surface and the second pressure-clamping surface. Is provided with means for controlling the surface temperatures of the first and second clamping surfaces to maintain Tg + 5 ° C. or higher, wherein Tg is the glass of the thermoplastic resin. Represents the transition temperature).
[13] The surface of both the first clamping surface and the second clamping surface has at least one temperature region portion equal to or higher than Tg and one temperature region portion lower than Tg, according to [12]. Film production equipment.
[14] The film manufacturing apparatus according to [12] or [13], wherein the means for controlling the surface temperature of the pressing surface is at least one cooling means.

  ADVANTAGE OF THE INVENTION According to this invention, when it uses for a liquid crystal display, sufficient optical compensation can be implement | achieved, a phase difference nonuniformity can be small, and a film with good peelability 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. Moreover, the manufacturing method of the film of this invention can be implemented simply by the film manufacturing apparatus 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 the present specification, unless otherwise specified, “Tg” represents “a glass transition temperature of a thermoplastic resin contained in a composition to be clamped by a clamping device”.

[Film produced by the production method of the present invention]
(In-plane retardation Re, thickness direction retardation Rth)
The film produced by the production method of the present invention (hereinafter also referred to as the film of the present invention) contains a thermoplastic resin, and has a wavelength of 550 nm measured from the normal line in a plane including the film tilt direction and the film normal line. Retardation Re [0 °], retardation Re [+ 40 °] measured from a direction inclined + 40 °, and retardation Re [−40 °] measured from a direction inclined −40 ° relative to the normal Preferably satisfy both the following formulas (II) and (III).
40 nm ≦ Re [0 °] ≦ 300 nm (II)
0 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 0 to 300 nm, more preferably 0 to 200 nm, and still more preferably 40 to 200 nm. In the film of the present invention, the in-plane retardation Re [0 °] is preferably 40 to 300 nm, more preferably 40 to 200 nm, and still more preferably 60 to 180 nm.
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.
| Re [+ 40 °] −Re [−40 °] |, Re [0 °] and Rth in the above preferred ranges can be produced by the production method of the present invention described later. In addition, when the optical film having the 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. be able to.

  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, it is preferably 80 μm or less, more preferably 60 μm or less, and particularly preferably 40 μm or less from the viewpoint of thinning. 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.

  The variation in Re [0 °] (hereinafter also referred to as ΔRe [0 °]), the variation in Re [+ 40 °], and the variation in Re [−40 °] become display unevenness when used in a liquid crystal display. Therefore, the variation is preferably as small as possible. Specifically, it is preferably within ± 5 nm, more preferably within ± 4 nm, and even more preferably within ± 2 nm. Similarly, the variation in the angle of the slow axis also causes display unevenness. Therefore, the variation is preferably as small as possible, specifically within ± 1 °, preferably within ± 0.5 °. It is more preferable that the angle is within ± 0.25 °.

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.
Further, the variation in Re [0 °] can be measured by the following method. Sampling is performed at any 10 or more positions 2 mm or more apart from each other on the film surface, Re [0 °] is measured by the above method, and the difference between the maximum value and the minimum value is the average value of Re [0 °]. Divide by, and the percentage value will be the variation. 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 variation in Re [+ 40 °] and Re [−40 °] can be measured by the following method. Sampling is performed at arbitrary 10 points or more on the film surface 2 mm or more away from each other, Re [+ 40 °] and Re [−40 °] are measured by the above method, and the difference between the maximum value and the minimum value is determined as Re Variations in [+ 40 °] and Re [−40 °] are assumed.
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。 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, 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).

[Materials used in the production method of the present invention]
(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, styrene-acrylic resins and styrene-maleic anhydride resins are preferable from the viewpoints of heat resistance and 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.
As the styrene-acrylic resin, “Delpet 980N” manufactured by Asahi Kasei Chemical Co., Ltd., which will be described later, can be used.

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 2008-74918. 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 Corporation.

  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. Preferred specific examples of the phosphite stabilizer include the following compounds, but the phosphite 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 adjusting agent:
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 method for producing a film of the present invention includes a step of continuously forming a film containing a thermoplastic resin-containing composition between a first clamping surface and a second clamping surface constituting a narrow pressure device. In the method for producing a film, the composition is narrowed at a pressure of 20 to 1000 MPa by the first clamping surface and the second clamping surface, and passed between the first clamping surface and the second clamping surface. The temperature of Tg + 5 ° C. or higher is controlled so that at least one of the first clamping surface and the second clamping surface has at least one temperature region portion above Tg and one temperature region portion below Tg. It is characterized by doing. Applying such a large pressure is a feature of the present invention that is different from the conventional method.
As the clamping device having the first clamping surface and the second clamping surface, for example, a combination of two rolls, a combination of a roll and a touch belt (single-sided belt method) described in JP 2000-219752 A, The combination of a belt and a belt (double-sided belt system) etc. are mentioned. Among these, two rolls are preferable because a high pressure of 20 to 1000 MPa can be applied uniformly. 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. Etc.) can be measured by passing them through two rolls. The composition to be passed through the narrow pressure device may be in a molten state or a solution state in an appropriate solvent, but is preferably in a molten state, more preferably in a melt-extruded state. preferable.
Further, the temperature of the composition passing between the first pressure-clamping surface and the second pressure-clamping surface of the narrow-pressure device is set to Tg + 5 ° C. or more, and at least one of the first pressure-clamping surface and the second pressure-clamping surface It is also one of the features of the present invention that the surface of the substrate has at least one temperature region portion equal to or higher than Tg and a temperature region portion lower than Tg. Conventionally, applying a high pressure of 20 to 1000 MPa to a composition containing a plastic resin has not been studied.
In the present specification, a composition containing a melt-extruded thermoplastic resin is also referred to as a melt.
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 of the die (hereinafter also referred to as the discharge temperature) is determined according to the melting temperature of the thermoplastic resin, but generally it is preferably about 190 to 300 ° C. 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. An automatic thickness adjustment die that calculates downstream film thickness and thickness deviation and feeds back the results to die thickness adjustment is also effective.
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 first from the melt, and then the other surface is peeled off from the other surface. preferable. In the manufacturing method of the present invention, there is no particular limitation on the relationship between the moving speed of the first pressing surface and the moving speed of the second pressing surface, but the moving speed of the first pressing surface is faster than the moving speed of the second pressing surface. By doing so, a shearing stress can be applied, and a retardation film having an inclined structure can be produced. At that time, the surface to be peeled first may be the first pressure-clamping surface or the second pressure-clamping surface, but from the viewpoint of suppressing the peeling dan, the surface to be peeled first is the first A pinching surface (a pinching surface having a high moving speed) is preferable.

In the production method of the present invention, the temperature of the composition passing between the first and second clamping surfaces is set to Tg + 5 ° C. or more, and the first and second clamping surfaces constituting the narrowing device are formed. It is passed between them to form a film. Thus, since the film which has a big inclination structure can be created by letting a pinching apparatus pass in the state of Tg + 5 degreeC or more of a thermoplastic resin, it is preferable.
The temperature of the composition when passing between the first pressure-clamping surface and the second pressure-clamping surface refers to the temperature immediately before passing between the two narrow-pressure surfaces of the composition.

  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 having the optical characteristics of the present invention is produced by applying a pressure of 20 to 1000 MPa between the pressure devices. A preferable roll pressure is 20 to 500 MPa, a more preferable pressure is 25 to 300 MPa, further preferably 25 to 200 MPa, and particularly preferably 30 to 150 MPa.

In the manufacturing method of the present invention, 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 adjusted to 0.60 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 preferably 0.60 to 0.99, and more preferably 0.75 to 0.98.
Movement speed ratio = speed of the second clamping surface / speed of the first clamping surface (I)

(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 not particularly limited, and can be, for example, 200 to 2000 mm.

(Clamping device temperature)
In the manufacturing method of the present invention, at least one of the first pressure-clamping surface and the second pressure-clamping surface of the narrow-pressure device has at least one temperature region portion that is equal to or higher than Tg and one temperature region portion that is less than Tg. Control to have. Although there is no restriction | limiting in particular as a clamping apparatus which enables such a structure, It is preferable to use the film manufacturing apparatus of this invention mentioned later.
In the manufacturing method of the present invention, the surfaces of both the first clamping surface and the second clamping surface may be controlled to have at least one temperature region portion equal to or higher than Tg and one temperature region portion lower than Tg. From the viewpoint of controlling the inclined structure in the film thickness direction, it is more preferable.

In the production method of the present invention, the letter T indicates that the temperature T1 (or C1) of at least one clamping surface in a portion 1 cm above the clamping surface from the portion where the thermoplastic resin-containing composition is narrowed is Tg or more. From the viewpoint of greatly expressing the reed, particularly Re [0 °]. Moreover, it is also preferable from the viewpoint of expressing a phase difference tilt structure with a large | Re [+ 40 °] −Re [−40 °] |. Here, the temperature in the upper 1 cm portion along the pinching surface from the portion where the composition is narrowed on the pinching surface of the first pinching surface and the second pinching surface which is peeled off first from the film-like composition is changed. The temperature at a portion 1 cm above the pressing surface from the portion where the composition is narrowed on the pressing surface of the first pressing surface and the second pressing surface that is to be peeled off from the film-like composition later. Is referred to as C1. Further, in the pressing surface of the first pressing surface and the second pressing surface that is peeled off first from the film-like composition, the temperature at the portion 1 cm below the pressing surface from the portion where the composition is narrowed is T2 It is. Furthermore, the temperature at the peeling point of the pinching surface of the first pinching surface and the second pinching surface, which is later peeled from the film-like composition, is C2. Further, in the present specification, “a portion 1 cm upward along the pinching surface from the portion where the thermoplastic resin-containing composition is narrowed” refers to the “starting pinching of the section where the thermoplastic resin-containing composition is pinched” A portion 1 cm upward from the portion along the clamping surface ”. Similarly, “the portion 1 cm below the pressure-clamping surface from the portion where the thermoplastic resin-containing composition is narrowed” means “the pressure-clamping surface from the pressure-clamping end portion of the section where the thermoplastic resin-containing composition is clamped”. A portion of 1 cm below along “.
In the production method of the present invention, T1 and C1 are preferably Tg + 15 ° C. or higher because a film having a large gradient structure can be produced. Further, the T1 and the C1 are particularly preferably Tg + 20 ° C. or higher.
The T1 and the C1 are preferably Tg + 130 ° C. or less, more preferably Tg + 100 ° C. or less, and more preferably Tg + 70 ° C. or less.
Further, the T1 and the C1 may be the same temperature or different. The difference between the T1 and the C1 is preferably 0 to 50 ° C., more preferably 5 to 30 ° C., and more preferably 10 to 30 ° C. from the viewpoint of expression of a large inclined structure and planarization. It is particularly preferred.

In the production method of the present invention, in the pressing surface of the first pressing surface and the second pressing surface that is peeled off first from the film-like composition, the portion 1 cm below the pressing surface from the position where the composition is narrowed The temperature T2 at the portion is preferably less than Tg, from the viewpoint of suppression of peeling dan and inclination structure unevenness, and more preferably Tg−5 ° C. or less. Further, the T2 is particularly preferably Tg-10 ° C or lower. Moreover, it is also preferable that it is cooled to room temperature.
Further, it is possible to suppress peeling dan when the temperature C2 at the peeling point of the clamping surface of the first clamping surface and the second clamping surface which is later peeled off from the film-like composition is Tg-100 ° C. or more and less than Tg. From the viewpoint of The C2 is more preferably Tg-50 ° C to Tg-5 ° C, and particularly preferably Tg-30 ° C to Tg-10 ° C. It is also preferable that it is cooled to room temperature.

  In the production method of the present invention, it is preferable that the difference between the T1 and the T2 or the difference between the C1 and the C2 is 5 to 100 ° C., since a peeling dan can be suppressed while expressing a large inclined structure. The difference between T1 and T2 is more preferably 10 to 80 ° C, and particularly preferably 20 to 60 ° C.

  In the production method of the present invention, depending on the conveying speed, the length from the portion where the thermoplastic resin-containing composition is pinched by the pinching device to the portion where the thermoplastic resin-containing composition is peeled off from the pinching device (containing the thermoplastic resin) The distance of the section where the composition is sandwiched is preferably 0.1 mm or more and less than 200 mm, more preferably 0.5 to 20 mm, and particularly preferably 1 to 10 mm. Thus, by shortening the distance of the section in which the thermoplastic resin-containing composition is sandwiched and rapidly cooling the film, the retardation in the preferred range and the optical retardation in the preferred range are not relaxed. A film having characteristics can be formed.

  In addition, as long as the temperature of the said T1 and the said T2 is the preferable range of this invention, in the area where the said thermoplastic resin containing composition is pinched, the temperature of a pinching surface is temperature from T1 to T2 continuously and gently. The temperature may change, and the temperature may change to T2 while fluctuating, for example, repeatedly rising or falling from T1 in the middle of the section, and there is a local temperature change portion in the middle of the section. There may be a part that sometimes exceeds T1 or falls below T2. The same applies to C1 and C2.

(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.

  When a touch roll and a chill roll are used in a cast using two rolls, the touch roll is first peeled off from the thermoplastic resin composition. Therefore, the roll surface temperature of the upper 1 cm portion along the touch roll from the location where the resin composition is narrowed becomes T1, and the roll surface temperature of the upper 1 cm portion along the chill roll becomes C1 from the location where the resin composition is narrowed. The roll surface temperature of the portion 1 cm below along the touch roll from the location where the resin composition is narrowed is T2, and the roll surface temperature at the point where the resin composition is peeled from the chill roll is C2.

  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.

  The surface of the two rolls (for example, a touch roll or a casting roll) preferably has an arithmetic average height Ra of 100 nm or less, more preferably 50 nm or less, and further preferably 25 nm or less.

  In the production method of the present invention, the width of each of the two rolls is not particularly limited, and can be freely changed and employed according to the width of the film-like melt.

  The roll pressure between the two rolls is 20 to 1000 MPa, the preferred roll pressure is 20 to 500 MPa, the preferred roll pressure is 25 to 300 MPa, more preferably 25 to 200 MPa, and particularly preferably 30 to 150 MPa.

  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. The cylinder set value varies depending on the resin material used and the material of the two rolls. For example, when the effective width of the film-like melt is 200 mm, it is preferably 3 to 100 KN, and preferably 3 to 50 KN. Is more preferable, and 3 to 25 KN is particularly preferable.

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.

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. It is preferable to produce a film. The peripheral speed ratio of the two rolls is preferably 0.60 to 0.99, and more preferably 0.75 to 0.98. Here, the peripheral speed ratio of the two rolls means the peripheral speed of the slow roll / the peripheral speed of the fast roll.
If the peripheral speed ratio of the two rolls is 0.60 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 0.60 to 0.99, since it is difficult to scratch the film surface and a film with 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, a bank (excess of melt stays on the roll and forms on the 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. Moreover, it can be manufactured while suppressing variations in Re [0 °], Re [+ 40 °] and Re [−40 °]. 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 may be driven at a constant speed or at different peripheral speeds, but are preferably driven at different peripheral speeds. The two rolls may be driven or driven independently. However, in order to suppress variations in Re [0 °], Re [+ 40 °] and Re [−40 °], 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 set temperature of the two rolls is preferably Tg−70 ° C. to Tg + 20 ° C., more preferably Tg−50 ° C. to Tg + 10 ° C., more preferably Tg−40 ° C., using the glass transition temperature Tg of the resin. Set to ~ Tg + 5 ° C. Such temperature control can be achieved by passing a temperature-controlled liquid or gas through the touch roll. In the present invention, the surface temperatures of the two rolls are the same as the surface temperatures of the first and second clamping surfaces of the clamping device described in the temperature of the clamping device, and the preferred ranges are also the same. Furthermore, the surface temperature of such two rolls can be achieved by a film manufacturing apparatus described later.
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 of eliminating variations in Re [0 °], Re [+ 40 °], and Re [−40 °], there is a method of increasing adhesion when a film-like melt comes into contact with a 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.

(Cast using roll and belt)
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, at least one roll and a belt (for example, It is also preferable to pass between the touch belt and the chill roll). Hereinafter, although the preferable aspect of the manufacturing method of this invention using at least 1 roll and a belt is demonstrated, about the preferable range of this roll, it is the same as the preferable range of the roll in the case of the casting using the said 2 rolls. is there. In addition, when using a touch belt and a chill roll in the cast using a roll and a belt, a touch belt will peel first from a thermoplastic resin composition. Accordingly, the belt surface temperature of the upper 1 cm portion along the touch belt from the portion where the resin composition is narrowed becomes T1, and the roll surface temperature of the upper 1 cm portion along the chill roll from the portion where the resin composition is narrowed becomes C1. The belt surface temperature of the portion 1 cm below along the touch belt from the position where the resin composition is narrowed is T2, and the roll surface temperature at the point where the resin composition is peeled from the chill roll is C2.

  The surface of the belt (for example, touch belt) preferably has an arithmetic average height Ra of 100 nm or less, more preferably 50 nm or less, and further preferably 25 nm or less.

  In the production method of the present invention, the lateral width of each of the belts is not particularly limited, and can be freely changed according to the width of the film-like melt.

  The pressure between the roll and the belt is 20 to 1000 MPa, the preferable pressure is 20 to 500 MPa, the more preferable pressure is 25 to 300 MPa, further preferably 25 to 200 MPa, and particularly preferably 30 to 150 MPa. .

The belt is preferably made of metal, more preferably hard chrome or nickel. Further, it is preferable that the belt is made of a metal because the surface has small irregularities and the film surface is hardly damaged. On the other hand, a rubber roll or a belt lined with rubber can be used without particular limitation as long as the pressure between the roll and the belt can be achieved. Moreover, the surface of the film is hardly damaged by using a belt having no seam.
As the belt, for example, a belt described in JP-A-2007-237495 can be used.

  Furthermore, in the production method of the present invention, by adjusting the peripheral speed ratio between the roll and the belt through which the film-like melt passes, a shear stress is applied when the molten resin passes through the roll and the belt. It is preferable to produce a film. The preferable range of the peripheral speed difference between the roll and the belt is the same as in the case of the two rolls.

  In the production method of the present invention, the belt driving method is not particularly limited. For example, it is preferable that the belt held by two holding rolls is driven by rotating the holding rolls. Moreover, it is preferable from a viewpoint of making a belt and a roll a peripheral speed difference that it is independent drive with a cast roll.

  Further, in order to increase the difference between Re [40 °] and Re [−40 °], a difference may be made between the surface temperature of the roll and the surface temperature of the belt. 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 roll and belt 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. Further, in the present invention, the surface temperature of the roll and the surface temperature of the belt are the same as the surface temperatures of the first clamping surface and the second clamping surface of the clamping device described in the temperature of the clamping device, and the preferred range is also It is the same. Furthermore, the surface temperature of such a roll and belt can be achieved by a film manufacturing apparatus described later.

  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 longitudinal draw 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.

[Film production equipment]
The film production apparatus of the present invention is a film production apparatus provided with a narrow pressure device having a first clamping surface and a second clamping surface, wherein the first clamping surface and the second clamping surface are the first clamping surface. And a composition containing a thermoplastic resin between the second pressure-clamping surface and the second pressure-clamping surface so that the composition can be continuously passed while being narrowed at a pressure of 20 to 1000 MPa. At least one surface of the two pinching surfaces has at least one temperature region portion equal to or higher than Tg and a temperature region portion lower than Tg, and is compressed between the first pressing surface and the second pressing surface. And a means for controlling the surface temperature of the first pressure-clamping surface and the second pressure-clamping surface so as to maintain the temperature of the composition to be Tg + 5 ° C. or higher. Here, the surfaces of both the first clamping surface and the second clamping surface have at least one temperature region portion of Tg or more and a temperature region portion of less than Tg, respectively. It is preferable from the viewpoint of control.
As a preferred embodiment of the clamping device, the clamping device described in the manufacturing method of the present invention can be used, and the temperature adjusting means and the pressure adjusting means are also in the clamping device described in the manufacturing method of the present invention. It is the same as each means. Among them, the production apparatus of the present invention has at least one cooling means as a temperature adjusting means for the pressure-clamping surface, and is peeled off first from the film-like composition between the first pressure-clamping surface and the second pressure-clamping surface. This is preferable from the viewpoint of adjusting the temperature at the peeling point to be within the preferable range.
As the film manufacturing apparatus of the present invention, the surface of the first pressure-clamping surface has at least one temperature region portion having a temperature of Tg or more and a temperature region portion of less than Tg, and the surface of the second pressure-clamping surface has a temperature of Tg or more. As a device having at least one region portion and a temperature region portion less than Tg, for example, a heating means (device) and a cooling means (device) are further installed at suitable positions in a conventionally known clamping device. A film manufacturing apparatus and the roll as described in Unexamined-Japanese-Patent No. 2006-256159 can be mentioned.
Although the preferable aspect of the film manufacturing apparatus of this invention is illustrated below, this invention is not restrict | limited by these specific examples.

Examples of the film manufacturing apparatus in which a heating apparatus and a cooling apparatus are further installed at suitable positions in the conventionally known clamping apparatus include a film manufacturing apparatus having an embodiment shown in FIG. In FIG. 1, a heating device 4a is provided above the chill roll 2, and a heating device 4b is provided above the touch roll 3a. By means of the heating device 4a and the heating device 4b, the upper surface temperature of the chill roll 2 at a portion of about 0.1 to 10 cm above the roll from the pinching portion (the point at which the touch roll and cast roll pinch the melt) The upper surface temperature of the touch roll 3a in the upper portion of about 0.1 to 10 cm along the roll from the pressure portion can be set to a temperature equal to or higher than the Tg of the molten resin 1. The lower part of the chill roll 2 and the touch roll 3a has a cooling device 5b. By the cooling device 5b, the lower surface temperature of the touch roll 3a at a portion of about 0.1 to 10 downward from the pinching part along the roll. Can be set to a temperature lower than Tg of the molten resin 1. That is, according to the control device of the present invention, the roll surface temperature T1 of the upper part 1 cm along the touch roll from the position where the resin composition is narrowed, and the upper part 1 cm along the chill roll from the position where the resin composition is narrowed It is possible to control the roll surface temperature C1 of the part and the roll surface temperature T2 of the part 1 cm below along the touch roll from the position where the resin composition is narrowed.
Moreover, the more preferable roll temperature distribution of this invention can be obtained by changing the preset temperature of the heating apparatus 4a, the heating apparatus 4b, and the cooling device 5b. Furthermore, by providing the cooling device 5a and setting the chill roll lower surface temperature C2 at the point where the film peels from the chill roll 2, the peelability can be further improved.
The T1, T2, C1, and C2 are temperatures in the above specific range, but may be controlled to be preferable temperatures in the production method of the present invention over a wide range of rolls. For example, if it is said T1, even if the part about 0.1-10 cm above a roll from the pinching part (part where a touch roll and a cast roll pinch | melt a melt) is a preferable range of said T1, it is a touch. The entire upper portion of the roll 3a may be within the preferable temperature range of T1. Similarly, the entire lower part of the touch roll 3a may satisfy T2, the entire upper part of the chill roll 2 may satisfy C1, and the entire lower part of the chill roll 2 may satisfy C2.

The cooling device 5a is preferably installed vertically downward from the peeling part of the chill roll 2 and the film-like melt from the viewpoint of suppressing a peeling dan when peeling the chill roll and the film. It is more preferable to install it at ˜20 cm. The cooling device 5b is preferably installed vertically downward from the portion where the touch roll and the cast roll are closest to each other because turbulence is unlikely to occur in the atmosphere below the touch roll and chill roll. More preferably, it is installed at 3-10 cm.
Needless to say, there is no limitation on the mode of the pinching device. For example, a pinching device of a combination of a chill roll and a touch roll can be used as the film manufacturing apparatus of the present invention by providing the heating device and the cooling device.

  In detail, the roll described in JP-A-2006-256159 includes an inner cylinder disposed non-rotatably, a rotatable outer cylinder disposed concentrically with the inner cylinder, and the inner cylinder. An annular medium flow passage formed by a gap between the outer peripheral surface of the outer cylinder and the inner peripheral surface of the outer cylinder, each extending in the axial direction of the inner cylinder and blocking the annular medium flow passage in the circumferential direction, A plurality of partition members that divide the medium flow path into a plurality of small medium flow paths, and shafts of the inner cylinder at different positions in the circumferential direction of the inner cylinder so as to be connected to the small medium flow paths, respectively. A plurality of slit-shaped medium inlets drilled in the flesh of the inner cylinder along the inner cylinder and the inner cylinder at different positions in the circumferential direction of the inner cylinder so as to connect to the respective small medium flow paths. Drilled into the flesh of the inner cylinder along the axis of the cylinder Heating, characterized in that it comprises a plurality of slit-shaped medium outlet that is, a, is a cooling roll. By adopting such a configuration, it is possible to control the surface temperature distribution of the roll according to the position, and it can be used as a clamping device used in the manufacturing method of the present invention.

As a first example of the embodiment using the roll described in JP-A-2006-256159, a chill roll 2 which is a roll described in JP-A-2006-256159 and a touch belt 3b shown in FIG. A mode in which the molten resin 1 is sandwiched and used is exemplified. The touch belt 3b heats or cools the entire surface temperature of each of the first holding roll 11a and the second holding roll 11b constituting the touch belt by a known method, for example, a liquid or gas whose temperature is adjusted inside the touch roll. Thus, the surface temperature distribution of the touch belt 3b can be controlled within the range of the present invention. In addition to the temperature control of the holding roll as described above, the temperature control of the touch belt can also be achieved by installing a heating device or a cooling device inside or near the outside of the belt.
As a second example of the embodiment using the roll described in JP-A-2006-256159, chill roll 2 which is a roll described in JP-A-2006-256159 shown in FIG. A mode in which the molten resin 1 is sandwiched by using the touch roll 3a which is a roll described in Japanese Patent No. 256159 is exemplified. Thus, by making both rolls into rolls described in JP-A-2006-256159, the roll surface temperature distribution can be controlled within the range of the present invention.

  There is no restriction | limiting in particular as said various heating apparatus and cooling device, A well-known heating means and cooling means can each be used. Moreover, although there is no restriction | limiting in particular in the width | variety of the said heating apparatus or cooling device, It is preferable to match | combine with the width | variety of the cast roll to be used.

(Polarizer)
A polarizing plate 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 will be described. Examples of the polarizing plate include those prepared for the purpose of two functions of a protective film and viewing angle compensation on one surface of the polarizing film, and a composite polarizing plate laminated on a protective film such as TAC. .

  If the said polarizing plate 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 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 can be used as at least one polarizing plate protective film. Moreover, the polarizing plate may have an adhesive layer for sticking to another member on at least one surface thereof. Moreover, in the said polarizing plate, if the surface of the film of this invention is a concavo-convex structure, it will have an anti-glare (anti-glare) function. Further, the polarizing plate further includes an antireflection film in which an antireflection layer (low refractive index layer) is further laminated on the surface of the film of the present invention, and an optical in which an optical anisotropic layer is further laminated on the surface of the film of the present invention. It is also preferable to use a compensation film.

  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.

  More preferably, the polarizing plate has a structure 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. 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 for the polarizing plate, 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.

  Any appropriate polarizer may be selected as long as it can achieve the object of the present invention. 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 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 another member such as another optical film or a liquid crystal cell can be provided on the side of the optical film where the polarizer is not adhered.

(Production method of polarizing plate)
A method for producing the polarizing plate will be described.
The said polarizing plate can be manufactured by bonding the single side | surface (surface treatment surface in the case of having surface-treated) of the film of this invention on the at least single side | surface of the said polarizer using an adhesive agent. Moreover, when bonding together a cellulose acylate film, a polarizer, and the film of this invention in order, the said polarizing plate can be manufactured by bonding a polarizer and another film on both surfaces of a polarizer using an adhesive agent.
In the manufacturing method of the said polarizing plate, 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 said polarizing plate 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 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, and is not limited. Specific examples of the image display device to which the polarizing plate 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). . 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 device)
The film of the present invention can be used in various modes of liquid crystal display devices. 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.

  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.

  It can also be set as a laminated | multilayer film by providing another layer to the film of this invention.

  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.

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

[Production Example 2] Preparation of cellulose acylate propionate (CAP) pellets Cellulose acetate propionate was produced according to the method described in Example 1 of JP-A-2006-348123, and pelletized according to a conventional method. . 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 temperature of the resin was 137 ° C.

[Production Example 3] Preparation of pellets of polycarbonate (PC) As polycarbonate, pellets of "Taflon MD1500" manufactured by Idemitsu Kosan Co., Ltd. were used. “Taflon MD1500” exhibits positive intrinsic birefringence. The glass transition temperature of the resin was 142 ° C.

[Production Example 4] Preparation of pellets of styrene copolymer (SMA) 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 temperature of the resin was 130 ° C.

[Example 1]
(Production of film)
The pellets of the 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 a die having a width of 450 mm at an extrusion temperature (discharge temperature) of 260 ° C.
Thereafter, the melt (molten resin) was extruded onto the cast roll using the film production apparatus of FIG. The temperature of the molten resin was 260 ° C. at the die discharge point. At this time, the cylinder was set so that the cast pressure (chill roll 2) having a width of 1800 mm on the most upstream side had the touch pressure (center pressure) shown in Table 1 below, and the touch roll 3a having a width of 300 mm was brought into contact therewith. Using these rolls, the peripheral speed ratio of the touch roll and the chill roll speed was set to the conditions shown in Table 1 below to form a film. The surface temperature of the touch roll and chill roll was set to be Tg-5 ° C. when an external heating device and cooling device were not used, and the distance between the die and the melt landing point was set to 200 mm. Next, infrared heaters 4a and 4b having a width of 1800 mm are installed in the upper 20 cm portion of each roll, and 1 cm upward along the roll from the pressure-clamping portion (the point where the touch roll and chill roll pinch the melt) at the top of the touch roll. The heater temperature was set so that the surface temperature T1 in the portion and the surface temperature C1 in the portion 1 cm upward from the pinching portion at the top of the chill roll became the temperatures shown in Table 1. Further, a cold air device 5a having a width of 1800 mm is installed at a lower portion of the chill roll 10 cm vertically from a peeling part of the chill roll and the film-like melt, and the touch roll and the chill roll are closest to the cold air device 5b having a width of 1800 mm. Installed at a position 10 cm vertically downward from the part, surface temperature T2 at the part 1 cm downward from the pinching part below the touch roll along the roll, surface temperature at the peeling point between the chill roll below the chill roll and the film-like melt The cooling air temperature was set so that C2 became the temperature described in Table 1 below. The film forming atmosphere was 60% humidity.
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 forming width was 200 mm, and the film was wound up by 450 m at a film forming speed of 5 m / min (chill roll speed). The thickness of the film after film formation was 60 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 also 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.

(Film peelability)
The peelability of the obtained film of Example 1 was evaluated according to the following evaluation method, and the results are shown in Table 1.
○: The film could be peeled off satisfactorily from the touch roll, and no peeling dan was confirmed.
X: When peeling a film from a touch roll, the peeling sound generate | occur | produced and the peeling Dan was able to be confirmed.
The stripping dan was evaluated from the measurement of film thickness unevenness using an interference film thickness meter (Laser Interferometer F601 Fujinon Co., Ltd.).
Moreover, the peeling sound was evaluated using a sound level meter (precision sound level meter NA-28 Lion Co., Ltd.).

[Examples 2 to 13, Comparative Examples 1 and 2]
Optical films of the respective examples and comparative examples were obtained in the same manner as in Example 1 except that the resin used and the film forming conditions were changed as described in Table 1 below. The optical properties of the optical films of each Example and Comparative Example are shown in Table 1 below.

From Table 1, it was found that in each of Examples 1 to 13, Re [0 °] was greatly expressed, and the peelability was also good. On the other hand, in Comparative Example 1, the T2 temperature was outside the range of the production method of the present invention, and Re [0 °] of the obtained film was small and the retardation unevenness was large, so that it was insufficient as a retardation film. In addition to performance, it was also poorly stripped. In Comparative Example 2, the T1 temperature was out of the range of the production method of the present invention, and 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, sufficient optical compensation is realized when used in a liquid crystal display by controlling the T1 temperature and the T2 temperature within the range of the present invention with the touch pressure as the range of the present invention. It was found that it was possible to produce a film with small phase difference unevenness and good peelability.
Furthermore, in Examples 5-7 and 9-12, it turned out that a film with a large phase difference inclination structure can be created by giving a peripheral speed difference to two rolls.

It is the schematic of the film manufacturing apparatus used in the Example of this invention. It is one aspect | mode of the Example of this invention using the touch belt and the cast roll of Unexamined-Japanese-Patent No. 2006-256159. It is one aspect | mode of the Example of this invention using the touch roll of Unexamined-Japanese-Patent No. 2006-256159 and the cast roll of Unexamined-Japanese-Patent No. 2006-256159.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Molten resin 2 Chill roll 3a Touch roll 3b Touch belt 4a Heating device 4b Heating device 5a Cooling device 5b Cooling device 11a 1st holding roll 11b 2nd holding roll C1 Cast roll surface temperature C2 in a pinching part Touch roll (belt) Cast roll surface temperature T1 at the peeled portion of the molten resin and touch roll (belt) surface temperature T2 at the pinched portion of the touch roll (belt)

Claims (14)

In the method for producing a film including a step of continuously forming a film containing a thermoplastic resin-containing composition between a first clamping surface and a second clamping surface constituting the narrow pressure device,
The composition is narrowed at a pressure of 20 to 1000 MPa by the first clamping surface and the second clamping surface,
The temperature of the composition that passes between the first clamping surface and the second clamping surface is Tg + 5 ° C. or higher, and at least one surface of the first clamping surface and the second clamping surface is Tg or higher. A method for producing a film, wherein the film is controlled so as to have at least one region portion and a temperature region portion less than Tg (where Tg represents a glass transition temperature of the thermoplastic resin).   The surface of both said 1st clamping surface and said 2nd clamping surface is controlled so that it may have at least 1 temperature region part more than Tg and temperature region part less than Tg, respectively. The manufacturing method of the film of description.   3. The method for producing a film according to claim 1, wherein the temperature T1 of at least one clamping surface in a portion 1 cm above the clamping surface from a position where the composition is narrowed is Tg or more. However, Tg represents the glass transition temperature of the said thermoplastic resin.)   Of the first pressure-clamping surface and the second pressure-clamping surface, the pressure-clamping surface that is peeled off first from the film-like composition has a temperature T2 of less than Tg at a portion 1 cm below the pressure-clamping surface from the position where the composition is narrowed The method for producing a film according to any one of claims 1 to 3, wherein Tg represents a glass transition temperature of the thermoplastic resin.   The method for producing a film according to claim 1, wherein the narrow pressure device is at least two rolls.   The method for producing a film according to claim 1, wherein the narrow pressure device is at least one roll and a belt.   Said T1 is Tg + 15 degreeC or more, The manufacturing method of the film of any one of Claims 1-6 (however, Tg represents the glass transition temperature of the said thermoplastic resin).   Said T2 is Tg-5 degrees C or less, The manufacturing method of the film of any one of Claims 1-7 (however, Tg represents the glass transition temperature of the said thermoplastic resin).   The method for producing a film according to any one of claims 1 to 8, wherein a difference between the T1 and the T2 is 5 to 100 ° C.   The length from the portion where the thermoplastic resin-containing composition is pinched by the pinching device to the portion where the thermoplastic resin-containing composition is peeled off from the pinching device is 0.1 mm or more and less than 200 mm. The manufacturing method of the film as described in any one of these.   A film produced by the method for producing a film according to claim 1. A film manufacturing apparatus comprising a narrow pressure device having a first clamping surface and a second clamping surface,
The first clamping surface and the second clamping surface allow a composition containing a thermoplastic resin to pass between the first clamping surface and the second clamping surface continuously while being narrowed at a pressure of 20 to 1000 MPa. Arranged to be able to
At least one of the first clamping surface and the second clamping surface has at least one temperature region portion that is equal to or higher than Tg and a temperature region portion that is less than Tg. A film comprising means for controlling the surface temperatures of the first and second clamping surfaces so as to maintain the temperature of the composition to be narrowed between the clamping surfaces at Tg + 5 ° C. or higher. Manufacturing apparatus (however, Tg represents the glass transition temperature of the thermoplastic resin).   13. The film production according to claim 12, wherein the surfaces of both the first clamping surface and the second clamping surface have at least one temperature region portion equal to or higher than Tg and one temperature region portion lower than Tg. apparatus.   14. The film manufacturing apparatus according to claim 12, wherein the means for controlling the surface temperature of the clamping surface is at least one cooling means.

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