JP2008023986A - Thermoplastic film, its manufacturing method, polarizing plate, reflection preventing film and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a thermoplastic film reduced in the temperature dependence of Re and Rth or the in-plane irregularity of the temperature dependence. <P>SOLUTION: The manufacturing method of the thermoplastic film is characterized in that a non-stretched film manufactured by a melt film forming method is heat-treated at a temperature of Tg-(Tg+60°C) while holding feed tension to 0.1-20 kg/m. Herein, Tg is the glass transition temperature of the non-stretched film. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thermoplastic film and a method for producing the same. The present invention also relates to a polarizing plate, an optical compensation film, and a liquid crystal display device using a thermoplastic film having excellent optical characteristics.

  There is a demand for low retardation of films used as protective films for polarizing films used in recent liquid crystal display devices. That is, an in-plane retardation value (Re; hereinafter simply referred to as “Re”) and a thickness direction retardation value (Rth; hereinafter simply referred to as “Rth”). There is a demand for thermoplastic films that are both in a small range (Re: 0 nm to 10 nm, Rth: 0 to 30 nm).

  As a thermoplastic film having a small retardation, a film made of a polycarbonate or a cycloolefin polymer has been proposed (for example, see Patent Documents 1 to 4). These films are commercially available, for example, as “ZEONOR” (manufactured by Nippon Zeon Co., Ltd.), “ARTON” (manufactured by JSR Corporation), and the like.

  In addition, a method of using a specific cellulose acylate resin as a thermoplastic film has also been proposed (see, for example, Patent Documents 5 and 6). In these, the carbon chain of the ester group of the cellulose acylate resin is lengthened to lower the melting point, thereby facilitating melt film formation. Specifically, the film formation by melt film formation is enabled by changing cellulose acetate into cellulose propionate, cellulose butyrate, or the like.

  However, liquid crystal display devices using these thermoplastic films have been clarified to cause color unevenness depending on the use temperature, and the improvement has been demanded.

JP 2001-318233 A JP 2002-328233 A JP 2004-151573 A JP 2005-134768 A JP 2000-352620 A JP 2006-63169 A

  An object of the present invention is to provide a thermoplastic film having a temperature dependency of Re and Rth of the thermoplastic film and a small in-plane unevenness of the temperature dependency, and a method for producing the same. Another object of the present invention is to provide a polarizing plate and an antireflection film using the thermoplastic film, and a liquid crystal display device with improved color unevenness.

That is, the object of the present invention has been achieved by the following means.
(1) An unstretched film formed by a melt film forming method is heat-treated at a temperature of Tg to (Tg + 60 ° C.) at a conveyance tension of 0.1 kg / m to 20 kg / m. Manufacturing method (the Tg represents the glass transition temperature of the unstretched film).
(2) A film of Re ≦ 10 nm and Rth ≦ 30 nm obtained by stretching an unstretched film formed by the melt film-forming method, at a temperature of Tg to (Tg + 60 ° C.), a conveyance tension of 0.1 kg / m to 20 kg / m A method for producing a thermoplastic film characterized by heat treatment in the above (Re represents an in-plane retardation at 25 ° C. and 60% relative humidity, and Rth represents a retardation in the thickness direction at 25 ° C. and 60% relative humidity) And the Tg represents the glass transition temperature of the unstretched film).
(3) An unstretched film having a residual solvent amount of 0.01% by mass or less is heat-treated at a temperature of Tg to (Tg + 60 ° C.) with a conveyance tension of 0.1 kg / m to 20 kg / m. A method for producing a thermoplastic film (the Tg represents the glass transition temperature of the unstretched film).
(4) A non-stretched film having a residual solvent amount of 0.01% by mass or less and a film satisfying Re ≦ 10 nm and Rth ≦ 30 nm at a temperature of Tg to (Tg + 60 ° C.) at a transport tension of 0.1 kg. / M to 20 kg / m, a method for producing a thermoplastic film (where Re represents in-plane retardation at 25 ° C. and 60% relative humidity, Rth represents 25 ° C. and 60% relative humidity) Represents the retardation in the thickness direction, and Tg represents the glass transition temperature of the unstretched film).
(5) The method for producing a thermoplastic film according to any one of (1) to (4), wherein the heat treatment is performed for 1 second to 60 minutes.
(6) The method for producing a thermoplastic film according to any one of (1) to (5), wherein the heat treatment is performed during a melt film-forming step.
(7) The manufacturing method according to any one of (1) to (6), wherein the unstretched film is formed using a touch roll method.
(8) A thermoplastic film characterized by satisfying the following formulas (1) and (2) and produced by a melt film-forming method.
Formula (1): Re ≦ 30 nm
Formula (2): ΔRetemp ≦ 10 nm
[In the above formula, Re represents in-plane retardation of the thermoplastic film at 25 ° C. and 60% relative humidity, ΔRe temp represents | Re-Re60 ° C., and Re 60 ° C. represents 60 ° C. of the thermoplastic film. -Represents in-plane retardation at 60% relative humidity. ]
(9) A thermoplastic film characterized by satisfying the following formulas (1) and (2) and having a residual solvent amount of 0.01% by mass or less.
Formula (1): Re ≦ 30 nm
Formula (2): ΔRe temp ≦ 10 nm
[In the above formula, Re represents in-plane retardation of the thermoplastic film at 25 ° C. and 60% relative humidity, ΔRe temp represents | Re-Re60 ° C., and Re 60 ° C. represents 60 ° C. of the thermoplastic film. -Represents in-plane retardation at 60% relative humidity. ]
(10) The thermoplastic film according to (8) or (9), wherein the following formulas (3) and (4) are satisfied.
Formula (3): | Rth | ≦ 30 nm
Formula (4): ΔRth temp ≦ 15 nm
[In the above formula, Rth represents retardation in the thickness direction at 25 ° C. and 60% relative humidity of the thermoplastic film, ΔRth temp represents | Rth−Rth60 ° C., and Rth60 ° C. represents 60 ° C. of the thermoplastic film] -Represents retardation in the thickness direction at a relative humidity of 60%. ]
(11) The thermoplastic film according to any one of (8) to (10), wherein the following formulas (5) and (6) are satisfied.
Formula (5): ΔRe film ≦ 5 nm
Formula (6): ΔRth film ≦ 5 nm
[In the above formula, ΔRe film represents the uneven distribution of ΔRe temp over the entire film surface of the thermoplastic film, and ΔRth film represents the uneven distribution of ΔRth temp over the entire film surface of the thermoplastic film. ΔRe temp represents | Re−Re60 ° C., Re represents in-plane retardation of the thermoplastic film at 25 ° C. and 60% relative humidity, and Re 60 ° C. represents 60 ° C. and 60% relative humidity of the thermoplastic film. In-plane retardation at. ΔRth temp represents | Rth−Rth60 ° C., Rth represents retardation in the thickness direction at 25 ° C. and relative humidity of 60% of the thermoplastic film, and Rth 60 ° C. represents 60 ° C. and relative humidity of 60% of the thermoplastic film. Represents retardation in the thickness direction. ]
(12) The thermoplastic film as described in any one of (8) to (11), which contains cellulose acylate satisfying the following formulas (S-1) and (S-2).
Formula (S-1): 2.5 <= A + B <3.0
Formula (S-2): 1.25 ≦ B <3
(In the formula, A represents the degree of substitution of the acetyl group with respect to the hydrogen atom constituting the hydroxyl group of cellulose, and B represents the sum of the degree of substitution of the propionyl group, butynyl group and pentanoyl group with respect to the hydrogen atom constituting the hydroxyl group of cellulose.)
(13) The thermoplastic film as described in any one of (8) to (11), comprising cellulose acylate having a composition satisfying the following formulas (T-1) and (T-2).
Formula (T-1): 2.5 <= A + C <3.0
Formula (T-2): 0.1 ≦ C <2
(In the formula, A represents the degree of substitution of the acetate group, and C represents a substituted or unsubstituted aromatic acyl group.)
(14) The thermoplastic film as described in any one of (8) to (11), which contains a saturated norbornene resin.
(15) The thermoplastic film as described in any one of (8) to (11), having a retardation satisfying the following formulas (R-1) and (R-2).
Formula (R-1): 0 nm ≦ Re ≦ 150 nm
Formula (R-2): 0 nm ≦ Rth ≦ 300 nm
(In the formula, Re represents the in-plane retardation of the thermoplastic film, and Rth represents the thickness direction retardation of the thermoplastic film.)
(16) The thermoplastic film according to any one of (8) to (15) is stretched with an aspect ratio L / W of more than 2 and 50 or less, or 0.01 to 0.3. A thermoplastic film.
(17) A thermoplastic film, wherein the thermoplastic film according to any one of (8) to (16) is preheated at a temperature higher by 1 ° C to 50 ° C than the stretching temperature before transverse stretching.
(18) A thermoplastic film obtained by heat-treating the thermoplastic film according to any one of (8) to (17) at a temperature lower by 1 ° C to 50 ° C than the stretching temperature after transverse stretching.
(19) After the thermoplastic film according to any one of (8) to (18) is subjected to longitudinal stretching or at least one of the lateral stretching, at (Tg-50) ° C to (Tg + 30) ° C. A thermoplastic film which has been heat relaxed while being conveyed with a tension of 0.1 kg / m to 20 kg / m.
(20) The thermoplastic film according to any one of (8) to (19), which is produced by the method for producing a thermoplastic film according to any one of (1) to (7). .
(21) A polarizing plate comprising at least one thermoplastic film according to any one of (8) to (20).
(22) An antireflection film comprising the thermoplastic film according to any one of (8) to (20).
(23) At least one of the thermoplastic film according to any one of (8) to (20), the polarizing plate according to (21), and the antireflection film according to (22) is used. A liquid crystal display device.

  ADVANTAGE OF THE INVENTION According to this invention, the thermoplastic film with small temperature dependence of Re and Rth of a thermoplastic film, and in-plane nonuniformity of this temperature dependence, and its manufacturing method can be provided. Moreover, according to this invention, a liquid crystal display device with little color unevenness can be provided by using the thermoplastic film of this invention, the polarizing plate using the thermoplastic film of this invention, and an antireflection film.

  As a result of intensive studies, the present inventors have found that the color unevenness accompanying the temperature change of the liquid crystal display device using the thermoplastic film is caused by the Re, Rth temperature fluctuation of the film. The Re and Rth temperature fluctuations are caused by distortion in the film generated in the film forming process (particularly between the die and the casting drum), and it has been found that this distortion can be eliminated by heat-treating the thermoplastic film under low tension conditions. It came to.

  Below, the thermoplastic film of this invention, its manufacturing method, and its application are demonstrated in detail. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

  In the method for producing a thermoplastic film of the present invention, an unstretched film formed by a melt film forming method is heat-treated at a temperature of Tg to (Tg + 60 ° C.) at a conveyance tension of 0.1 kg / m to 20 kg / m. It is characterized by. In the present invention, instead of an unstretched film formed by the melt film forming method, a film with Re ≦ 10 nm and Rth ≦ 30 nm formed by the melt film forming method; an amount of residual solvent of 0.01% by mass or less A stretched film; or a film having a residual solvent amount of 0.01% by mass or less, Re ≦ 10 nm, and Rth ≦ 30 nm may be used. In the description of the present invention described below, the description will be made mainly on the case of using an unstretched film formed by a melt film forming method, but the same applies to the case where the above-mentioned film other than the unstretched film is used. The present invention can be implemented.

The thermoplastic film production method of the present invention aims to reduce the Re and Rth temperature fluctuations in a film having a small Re and Rth and an unstretched film.
In the present invention, the “unstretched film” means a film that is not substantially stretched. In general, a film with Re ≦ 10 nm and Rth ≦ 30 nm is applicable, and Re and Rth that are developed with stretching are small.

In the method for producing a thermoplastic resin film of the present invention, it is important to produce the film in the following process.
1) The method for producing a thermoplastic film of the present invention comprises an unstretched thermoplastic film (including a film that is in the process of film formation if it is formed into a film) Tg to (Tg + 60 ° C.), more preferably Tg. It heat-processes at the temperature of-(Tg + 50 degreeC), More preferably, Tg- (Tg + 40 degreeC). In the present specification, “Tg” means the glass transition temperature of the unstretched film.
When the temperature of the heat treatment is lower than the Tg, the retardation temperature dependency is not reduced because the distortion reducing effect in the film is small. On the other hand, when the temperature of the heat treatment is higher than (Tg + 60 ° C.), the effect of eliminating distortion is great, but the thermoplastic resin melts so that the film shape cannot be maintained and heat treatment becomes impossible.

  The heat treatment is performed while transporting the film, and the transport tension is 0.1 kg / m to 20 kg / m. The conveyance tension is more preferably 0.3 kg / m to 10 kg / m, and further preferably 0.5 kg / m to 8 kg / m. When the conveyance tension is less than 0.1 kg / m, sufficient conveyance cannot be performed. On the other hand, when the conveyance tension is greater than 20 kg / m, the stretching effect of the film acts more than the distortion elimination effect by heat treatment, and retardation is developed.

  The heat treatment time for the heat treatment is preferably 1 second to 60 minutes. As said heat processing time, 1 second-20 minutes are more preferable, More preferably, it is 1 second-10 minutes. When the heat treatment time is 1 second or longer, sufficient heat treatment can be performed, and when the heat treatment time is 60 minutes or shorter, molecular weight reduction and coloring due to deterioration of the thermoplastic resin due to heating can be suppressed.

2) The above heat treatment method can be carried out by (i) carrying an unstretched thermoplastic film on a roll set at the heat treatment temperature, or (ii) passing through a heat treatment zone set at a predetermined temperature, iii) A method of heating the film with a radiant heat source such as an IR heater or a halogen heater may be used. The heat treatment may be any method other than the above (i) to (iii) as long as it can reduce the strain in the unstretched thermoplastic film.

  More specifically, in the case of the method (i), the heat treatment can be performed during the conveyance of the unstretched film using one or a plurality of rolls set to the heat treatment temperature. Furthermore, the roll temperature when using a plurality of rolls may be the same or different. When the roll temperatures are different, the temperature sequence may be increased or decreased with respect to the transport direction, or a combination thereof.

The number of rolls in the method (i) may be any number as long as it can stably transport an unstretched film. Specifically, 2 to 7 is preferable, and 3 to 5 is more preferable. . As the roll, any form of roll such as a casting drum or a heat roll may be used as long as the purpose can be achieved.

  In the case of the method (ii), for example, a thermostatic bath can be used as the heat treatment zone. The thermostat may be in any form as long as it is a device capable of heat-treating an unstretched film at a set temperature, for example, warming the entire thermostat with warm air set at a predetermined temperature. Alternatively, warm air may be blown onto the film, or the inside of the thermostatic chamber may be set to a desired temperature using a heater. As long as the unstretched film can be uniformly heated, the attachment position of such a heating device such as a heater may be attached to any position inside the thermostat. Regarding the temperature distribution inside the thermostatic chamber, the temperature may be increased from the entrance toward the exit, the temperature may be decreased, or the temperature increase and decrease may be repeated.

  In the case of the method (iii), the heater may be attached on one side or both sides of the unstretched film, but it is preferable to heat from both sides of the film because it can be heated more uniformly and efficiently. Although the number of heaters may be one or more, it is preferable to use a plurality of heaters as necessary in order to proceed the heat treatment more completely. When a plurality of heaters are used, the output may be set in any manner depending on the temperature and conditions necessary for the heat treatment. When using a plurality of heaters, the heater outputs may all be the same or different.

Even when the heat treatment methods (i) to (iii) are used, the extruded thin film thermoplastic resin in the molten state (this is also included in the “film” to be subjected to the heat treatment in this application) has a high temperature. By performing the heat treatment as it is, the effect becomes higher. For this reason, it is preferable to incorporate a heat treatment step after the time of film formation in the melt film forming step. In other words, it is preferable to perform the heat treatment during the film forming process rather than performing the heat treatment offline after the film formation. Therefore, it is preferable to use the method (i) or (ii) as the heat treatment step,
The method (i) is particularly preferable because a normal film forming apparatus can be used as it is.

The unstretched thermoplastic film which satisfy | fills the following physical properties (Formula (1)-(6)) can be produced with the manufacturing method of the thermoplastic film of the above-mentioned this invention.
That is, the thermoplastic film of the present invention satisfies at least the following formulas (1) and (2). The thermoplastic film of the present invention is also characterized by being produced by a melt film-forming method or having a residual solvent amount of 0.01% by mass or less.
Formula (1): In-plane retardation (Re) ≦ 30 nm
Formula (2): Change in Re between 25 ° C. and 60 ° C. (ΔRe temp) ≦ 10 nm

In the formula (1), the in-plane retardation (Re) is 10 nm or less, preferably 7 nm or less, particularly preferably 5 nm or less.
In the above formula (2), the change in Re (ΔRe temp) between 25 ° C. and 60 ° C. is 30 nm or less, preferably 25 nm or less, particularly preferably 20 nm or less.

It is preferable that the thermoplastic film of the present invention further satisfies the following formulas (3) and (4).
Formula (3): Absolute value of retardation in thickness direction (| Rth |) ≦ 30 nm
Formula (4): Change in Rth between 25 ° C. and 60 ° C. (ΔRth temp) ≦ 15 nm

In the formula (3), the absolute value (| Rth |) of retardation in the thickness direction is 30 nm or less, preferably 20 nm or less, particularly preferably 10 nm or less.
In the formula (4), the change in Rth (ΔRth temp) between 25 ° C. and 60 ° C. is 15
It is nm or less, preferably 11 nm or less, particularly preferably 8 nm or less.

It has been clarified that the unstretched film subjected to the above heat treatment has less in-plane unevenness due to retardation temperature dependency. The cause of this is not clear, but it is presumed that the uneven strain in the film plane was eliminated by heat treatment. A film having the following physical properties can be produced by such a heat treatment effect on the unstretched film.
That is, it is preferable that the thermoplastic film of the present invention further satisfies the following formulas (5) and (6).
Formula (5): ΔRe temp distribution unevenness (ΔRe film) ≦ 5 nm on the entire film surface
Formula (6): ΔRth temp distribution unevenness (ΔRth film) ≦ 5 nm on the entire film surface

Formula (5): ΔRe temp distribution unevenness (ΔRe film) on the entire film surface is 5 nm or less, preferably 4 nm or less, particularly preferably 2 nm or less.
Formula (6): ΔRth temp distribution unevenness (ΔRth film) on the entire film surface is 5 nm or less, preferably 4 nm or less, particularly preferably 2 nm or less.

Hereinafter, the present invention will be described in order.
Preferred examples of the thermoplastic film of the present invention include a transparent thermoplastic film composed of at least one selected from a cellulose acylate resin, a polycarbonate resin, and a saturated norbornene resin. Of these, cellulose acylate resins and saturated norbornene resins are preferred.

<Cellulose acylate resin>
The cellulose acylate resin that can be used in the present invention preferably has the following characteristics. Here, A represents the degree of substitution of acetyl groups with respect to hydrogen atoms constituting the hydroxyl groups of cellulose, and B represents the sum of the degree of substitution of propionyl groups, butyryl groups and pentanoyl groups with respect to hydrogen atoms constituting the hydroxyl groups of cellulose. In the present invention, the degree of substitution refers to the ratio of hydrogen atoms constituting the hydroxyl group of cellulose at each of the 2-position, 3-position and 6-position (for example, 100% esterification is represented by substitution degree = 1). Means the sum of In addition, natural cellulose raw materials contain components other than cellulose, such as polymers (hemicellulose) of constituent sugars other than glucose (for example, xylose, mannose, etc.) and lignin corresponding to the organism or purification method from which they are derived. However, in the present invention, acylates produced using cellulose raw materials containing these as raw materials are also collectively referred to as cellulose acylates.
2.5 ≦ A + B <3.0
1.25 ≦ B <3
More preferably,
When 1/2 or more of B is a propionyl group 2.6 ≦ A + B ≦ 2.95
2.0 ≦ B ≦ 2.95
When less than 1/2 of B is a propionyl group 2.6 ≦ A + B ≦ 2.95
1.3 ≦ B ≦ 2.5
More preferably,
When ½ or more of B is a propionyl group 2.7 ≦ A + B ≦ 2.95
2.4 ≦ B ≦ 2.9
When less than 1/2 of B is a propionyl group 2.7 ≦ A + B ≦ 2.95
1.3 ≦ B ≦ 2.0

  The cellulose acylate resin is characterized in that the degree of substitution of acetyl groups in the acyl group is reduced and the sum of the degrees of substitution of propionyl groups, butyryl groups, and pentanoyl groups is increased. Thereby, it is easy to lower the melt viscosity, and it can be in a desired viscosity range. This is to increase the free volume between molecules by increasing the number of these groups longer than the acetyl group, and to suppress the increase in viscosity due to entanglement. However, if the acyl group is longer than the above, the glass transition temperature (Tg) and elastic modulus are excessively lowered, which is not preferable. For this reason, a propionyl group, a butyryl group, and a pentanoyl group larger than an acetyl group are preferable, a propionyl group and a butyryl group are more preferable, and a propionyl group is more preferable.

  The method for producing the cellulose acylate resin will be described in detail. The raw material cotton and the synthesis method of the cellulose acylate resin are also described in detail on pages 7 to 12 of the Japan Society for Invention and Technology (Publication No. 2001-1745, published on March 15, 2001, Japan Institute of Invention). ing.

(Raw material and pretreatment)
As the cellulose raw material, those derived from hardwood pulp, softwood pulp and cotton linter are preferably used. As a cellulose raw material, it is preferable to use a high-purity material having an α-cellulose content of 92 mass% to 99.9 mass%.
When the cellulose raw material is in the form of a film or a lump, it is preferable to pulverize in advance, and it is preferable that the pulverization proceeds until the cellulose form is fluffy.

(Pretreatment (activation))
Prior to acylation, the cellulose raw material is preferably subjected to a treatment (activation) for contact with an activator. As the activator, carboxylic acid or water can be used. However, when water is used, an excess of acid anhydride is added after activation to perform dehydration or to replace water. It is preferable to include a step of washing with an acid or adjusting acylation conditions. The activator may be added by adjusting to any temperature, and the addition method can be selected from spraying, dropping, dipping and the like.

  Preferred carboxylic acids as the activator are carboxylic acids having 2 to 7 carbon atoms (for example, acetic acid, propionic acid, butyric acid, 2-methylpropionic acid, valeric acid, 3-methylbutyric acid, 2-methylbutyric acid, 2,2 -Dimethylpropionic acid (pivalic acid), hexanoic acid, 2-methylvaleric acid, 3-methylvaleric acid, 4-methylvaleric acid, 2,2-dimethylbutyric acid, 2,3-dimethylbutyric acid, 3,3-dimethylbutyric acid , Cyclopentanecarboxylic acid, heptanoic acid, cyclohexanecarboxylic acid, benzoic acid and the like, more preferably acetic acid, propionic acid, or butyric acid, and particularly preferably acetic acid.

  At the time of activation, an acylation catalyst such as sulfuric acid can be further added as necessary. However, when a strong acid such as sulfuric acid is added, depolymerization may be promoted. Therefore, the addition amount is preferably limited to about 0.1% by mass to 10% by mass with respect to cellulose. Two or more kinds of activators may be used in combination, or an acid anhydride of a carboxylic acid having 2 to 7 carbon atoms may be added.

  The addition amount of the activator is preferably 5% by mass or more, more preferably 10% by mass or more, and particularly preferably 30% by mass or more based on cellulose. It is preferable that the amount of the activator is equal to or more than the lower limit value because problems such as a decrease in the degree of activation of cellulose do not occur. The upper limit of the addition amount of the activator is not particularly limited as long as productivity is not lowered, but it is preferably 100 times or less, more preferably 20 times or less, and 10 times or less by mass with respect to cellulose. It is particularly preferred that Activation may be carried out by adding a large excess of activator to cellulose, and then the amount of the activator may be reduced by performing operations such as filtration, air drying, heat drying, distillation under reduced pressure, and solvent substitution.

  The activation time is preferably 20 minutes or more, and the upper limit thereof is not particularly limited as long as it does not affect the productivity, but is preferably 72 hours or less, more preferably 24 hours or less, Especially preferably, it is 12 hours or less. The activation temperature is preferably 0 ° C to 90 ° C, more preferably 15 ° C to 80 ° C, and particularly preferably 20 ° C to 60 ° C. The step of activating cellulose can also be performed under pressure or reduced pressure. Moreover, you may use electromagnetic waves, such as a microwave and infrared rays, as a heating means.

By such activation treatment, the number of bright spot foreign matters in the film can be 25 / cm ² or less, more preferably 22 / cm ² or less, and still more preferably 20 / cm ² or less. Here, the “bright spot” is a diameter observed from the side of the other polarizing plate when light is applied from one polarizing plate to an optical film arranged between two polarizing plates arranged in a crossed Nicol state. It refers to a bright spot of 0.01 mm or more. This bright spot is derived from unreacted cellulose in cellulose acylate. That is, since the acylating agent does not penetrate into the inside of the cellulose, it is caused by unreacted cellulose remaining. For this reason, a bright spot can be reduced by making it fully swell to the inside of a cellulose by an activation process as mentioned above, and making it easy to make an acylating agent osmose | permeate. The bright spot is derived from the original cellulose having a fibrous shape, and has an elongated needle shape. For this reason, it is preferable to remove from the reaction stage as in the present invention because the filtration cannot pass through the space between the filter media sufficiently.
If there is a foreign substance that is the basis of such a bright spot, non-uniformity occurs in the melt, and residual distortion is likely to occur when cooling between the die and the casting drum (CD), which is a variation in Re and Rth. (Difference before and after 60 ° C.).

(Acylation)
In the method of synthesizing the cellulose acylate resin, it is preferable to acylate the hydroxyl group of cellulose by adding an acid anhydride of carboxylic acid to cellulose and reacting with Bronsted acid or Lewis acid as a catalyst. Cellulose mixed acylate can be obtained by mixing two carboxylic acid anhydrides as acylating agents or reacting them by sequential addition; mixed acid anhydrides of two carboxylic acids (for example, acetic acid / propionic acid mixed acid anhydride). A mixed acid anhydride (for example, acetic acid / propionic acid mixed acid anhydride) in a reaction system using an acid anhydride (for example, acetic acid and propionic acid anhydride) of a carboxylic acid and another carboxylic acid as a raw material. ) And reacting with cellulose; a cellulose acylate resin having a substitution degree of less than 3 is once synthesized, and a method of further acylating the remaining hydroxyl group with an acid anhydride or acid halide is used. Can do.

(Acid anhydride)
Preferred examples of the carboxylic acid anhydride include compounds having 2 to 7 carbon atoms as the carboxylic acid. Examples of the acid anhydride include acetic anhydride, propionic anhydride, butyric anhydride, 2-methylpropionic anhydride, valeric anhydride, 3-methylbutyric anhydride, 2-methylbutyric anhydride, 2, 2-dimethylpropionic anhydride (pivalic anhydride), hexanoic anhydride, 2-methylvaleric anhydride, 3-methylvaleric anhydride, 4-methylvaleric anhydride, 2,2-dimethylbutyric anhydride And 2,3-dimethylbutyric anhydride, 3,3-dimethylbutyric anhydride, cyclopentanecarboxylic anhydride, heptanoic anhydride, cyclohexanecarboxylic anhydride, benzoic anhydride, and the like.
The acid anhydride is more preferably an anhydride such as acetic anhydride, propionic anhydride, butyric anhydride, valeric anhydride, hexanoic anhydride, heptanoic anhydride, particularly preferably acetic anhydride. , Propionic anhydride, butyric anhydride.
For the purpose of preparing a mixed ester, it is preferable to use these acid anhydrides in combination. The mixing ratio is preferably determined according to the substitution ratio of the target mixed ester. The acid anhydride is usually added in excess equivalent to the cellulose. That is, it is preferable to add 1.2-50 equivalent with respect to the hydroxyl group of a cellulose, it is more preferable to add 1.5-30 equivalent, and it is especially preferable to add 2-10 equivalent.

(catalyst)
It is preferable to use a Bronsted acid or a Lewis acid as an acylation catalyst used in the production of the cellulose acylate resin. The definitions of Bronsted acid and Lewis acid are described in, for example, “Physical and Chemical Dictionary”, 5th edition (2000). Examples of preferable Bronsted acid include sulfuric acid, perchloric acid, phosphoric acid, methanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid and the like. Examples of preferred Lewis acids include zinc chloride, tin chloride, antimony chloride, magnesium chloride and the like.
As the catalyst, sulfuric acid or perchloric acid is more preferable, and sulfuric acid is particularly preferable. The preferable addition amount of a catalyst is 0.1-30 mass% with respect to a cellulose, More preferably, it is 1-15 mass%, Most preferably, it is 3-12 mass%.

(solvent)
In carrying out acylation, a solvent may be added for the purpose of adjusting viscosity, reaction rate, stirring ability, acyl substitution ratio, and the like. As such a solvent, dichloromethane, chloroform, carboxylic acid, acetone, ethyl methyl ketone, toluene, dimethyl sulfoxide, sulfolane and the like can be used, but carboxylic acid is preferable, for example, a carboxylic acid having 2 to 7 carbon atoms. Acids {eg acetic acid, propionic acid, butyric acid, 2-methylpropionic acid, valeric acid, 3-methylbutyric acid, 2-methylbutyric acid, 2,2-dimethylpropionic acid (pivalic acid), hexanoic acid, 2-methylvaleric acid , 3-methylvaleric acid, 4-methylvaleric acid, 2,2-dimethylbutyric acid, 2,3-dimethylbutyric acid, 3,3-dimethylbutyric acid, cyclopentanecarboxylic acid} and the like. More preferable examples include acetic acid, propionic acid, butyric acid and the like. These solvents may be used as a mixture.

(Conditions for acylation)
When acylation is performed, an acid anhydride and a catalyst, and further, if necessary, a solvent may be mixed and then mixed with cellulose, or these may be separately mixed with cellulose. It is preferable to prepare a mixture of an acid anhydride and a catalyst or a mixture of an acid anhydride, a catalyst and a solvent as an acylating agent and then react with cellulose. In order to suppress an increase in temperature in the reaction vessel due to reaction heat during acylation, the acylating agent is preferably cooled in advance. In this case, the cooling temperature is preferably −50 ° C. to 20 ° C., more preferably −35 ° C. to 10 ° C., and particularly preferably −25 ° C. to 5 ° C. The acylating agent may be added in a liquid state or may be frozen and added as a crystal, flake or block solid.

  Further, the acylating agent may be added to the cellulose at once or dividedly. In addition, cellulose may be added to the acylating agent all at once or in divided portions. When the acylating agent is added in portions, the same acylating agent or a plurality of different acylating agents may be used. As a preferred example, 1) a mixture of acid anhydride and solvent is added first, then the catalyst is added, and 2) a mixture of acid anhydride and solvent and a portion of the catalyst is added first, then the catalyst Add the mixture of the rest and solvent 3) Add the mixture of acid anhydride and solvent first, then add the mixture of catalyst and solvent 4) Add the solvent first, acid anhydride and catalyst Or a mixture of an acid anhydride, a catalyst, and a solvent.

Although acylation of cellulose is an exothermic reaction, in the method for producing the cellulose acylate resin, it is preferable that the maximum temperature reached during acylation is 50 ° C. or less. It is preferable that the reaction temperature is lower than this temperature because depolymerization proceeds and there is no inconvenience such as difficulty in obtaining a cellulose acylate resin having a polymerization degree suitable for the use of the present invention. The maximum temperature reached during acylation is preferably 45 ° C. or lower, more preferably 40 ° C. or lower, and particularly preferably 35 ° C. or lower. The reaction temperature may be controlled using a temperature control device or may be controlled by the initial temperature of the acylating agent. The reaction temperature can also be controlled by reducing the pressure of the reaction vessel and the heat of vaporization of the liquid component in the reaction system. Since the exotherm during the acylation is large in the initial stage of the reaction, it is possible to control such as cooling in the initial stage of the reaction and heating thereafter. The end point of acylation can be determined by means such as light transmittance, solution viscosity, temperature change of the reaction system, solubility of the reaction product in an organic solvent, and observation with a polarizing microscope.
The minimum reaction temperature is preferably −50 ° C. or higher, more preferably −30 ° C. or higher, and particularly preferably −20 ° C. or higher. A preferable acylation time is 0.5 to 24 hours, more preferably 1 to 12 hours, and particularly preferably 1.5 to 6 hours. If it is 0.5 hours or less, the reaction may not sufficiently proceed under normal reaction conditions, and if it exceeds 24 hours, it is not preferable for industrial production.

(Reaction terminator)
In the method for producing the cellulose acylate resin used in the present invention, it is preferable to add a reaction terminator after the acylation reaction.
The reaction terminator may be any as long as it decomposes an acid anhydride, and preferred examples include water, alcohol (eg, ethanol, methanol, propanol, isopropyl alcohol, etc.) or a composition containing these. Can be mentioned. Moreover, the reaction terminator may contain a neutralizing agent described later. When adding the reaction terminator, there is a case where a large heat generation exceeding the cooling capacity of the reactor occurs, which may cause a decrease in the degree of polymerization of the cellulose acylate resin, or the cellulose acylate may precipitate in an undesired form. In order to avoid such disadvantages, it is preferable to add a mixture of carboxylic acid such as acetic acid, propionic acid and butyric acid and water rather than directly adding water or alcohol, and acetic acid is particularly preferable as the carboxylic acid. The composition ratio of carboxylic acid and water can be used at any ratio, but the water content is 5% by mass to 80% by mass, further 10% by mass to 60% by mass, and particularly 15% by mass to 50% by mass. It is preferable to be in the range.

  The reaction terminator may be added to the acylation reaction vessel or the reactant may be added to the reaction terminator vessel. The reaction terminator is preferably added over 3 minutes to 3 hours. If the addition time of the reaction terminator is 3 minutes or more, the exotherm becomes too large, causing a decrease in the degree of polymerization, insufficient hydrolysis of the acid anhydride, and the stability of the cellulose acylate resin. This is preferable because there is no inconvenience such as reduction. Moreover, it is preferable that the addition time of the reaction terminator is 3 hours or less because problems such as industrial productivity decrease do not occur. The addition time of the reaction terminator is preferably 4 minutes to 2 hours, more preferably 5 minutes to 1 hour, and particularly preferably 10 minutes to 45 minutes. When adding the reaction terminator, the reaction vessel may or may not be cooled, but for the purpose of suppressing depolymerization, it is preferable to cool the reaction vessel to suppress the temperature rise. It is also preferable to cool the reaction terminator.

(Neutralizer)
In order to hydrolyze excess carboxylic anhydride remaining in the system or neutralize part or all of the carboxylic acid and esterification catalyst after the acylation termination step or the acylation termination step, Additives (eg, calcium, magnesium, iron, aluminum or zinc carbonates, acetates, hydroxides or oxides) or solutions thereof may be added. As a solvent for the neutralizing agent, water, alcohol (eg, ethanol, methanol, propanol, isopropyl alcohol, etc.), carboxylic acid (eg, acetic acid, propionic acid, butyric acid, etc.), ketone (eg, acetone, ethyl methyl ketone, etc.), Preferred examples include polar solvents such as dimethyl sulfoxide and mixed solvents thereof.

(Partial hydrolysis)
The cellulose acylate resin thus obtained has a total degree of substitution of nearly 3. However, for the purpose of obtaining a desired degree of substitution, a small amount of catalyst (generally, a remaining acyl such as sulfuric acid) is used. The ester bond is partially hydrolyzed by keeping it at 20 to 90 ° C. for several minutes to several days in the presence of water and a catalyst to reduce the acyl substitution degree of the cellulose acylate resin to a desired level. (So-called aging) is generally performed. Since the cellulose sulfate ester is also hydrolyzed during the partial hydrolysis, the amount of sulfate ester bound to the cellulose can be reduced by adjusting the hydrolysis conditions.
When the desired cellulose acylate is obtained, it is preferable to completely neutralize the catalyst remaining in the system using the neutralizing agent as described above or a solution thereof to stop partial hydrolysis. . By adding a neutralizing agent (for example, magnesium carbonate, magnesium acetate, etc.) that generates a salt that is poorly soluble in the reaction solution, a catalyst (for example, sulfate ester) bound to the solution or cellulose is effectively removed. It is also preferable to remove.

(Filtration)
The reaction mixture (dope) is preferably filtered for the purpose of removing or reducing unreacted substances, hardly soluble salts, and other foreign matters in the cellulose acylate. Filtration may be performed at any step between the completion of acylation and reprecipitation. For the purpose of controlling filtration pressure and handleability, it is also preferable to dilute with an appropriate solvent prior to filtration.

(Reprecipitation)
The cellulose acylate solution thus obtained is mixed in a poor solvent such as water or an aqueous solution of carboxylic acid (for example, acetic acid, propionic acid, etc.), or the poor solvent is mixed in the cellulose acylate solution. As a result, the cellulose acylate resin can be reprecipitated, and the desired cellulose acylate resin can be obtained by washing and stabilizing treatment. Reprecipitation may be carried out continuously or batchwise by a fixed amount. It is also preferable to control the form and molecular weight distribution of the re-precipitated cellulose acylate resin by adjusting the concentration of the cellulose acylate solution and the composition of the poor solvent according to the substitution mode of the cellulose acylate resin or the degree of polymerization.

(Washing)
The produced cellulose acylate resin is preferably washed. Any washing solvent may be used as long as it has low solubility of the cellulose acylate resin and can remove impurities, but water or warm water is usually used as washing water. The temperature of the washing water is preferably 25 ° C to 100 ° C, more preferably 30 ° C to 90 ° C, and particularly preferably 40 ° C to 80 ° C. The washing treatment may be performed in a so-called batch system in which filtration and replacement with a washing liquid are repeated, or may be carried out using a continuous washing apparatus. It is also preferable to reuse the waste liquid generated in the reprecipitation and washing steps as a poor solvent in the reprecipitation step, or to recover and reuse a solvent such as carboxylic acid by means such as distillation.
The progress of washing may be traced by any means, but preferable examples include methods such as hydrogen ion concentration, ion chromatography, electrical conductivity, ICP, elemental analysis, and atomic absorption spectrum.
By such treatment, the catalyst (sulfuric acid, perchloric acid, trifluoroacetic acid, p-toluenesulfonic acid, methanesulfonic acid, zinc chloride, etc.) in the cellulose acylate, neutralizer (for example, calcium, magnesium, iron, Aluminum or zinc carbonates, acetates, hydroxides or oxides), reaction products of neutralizing agents with catalysts, carboxylic acids (eg acetic acid, propionic acid, butyric acid), reactions of neutralizing agents with carboxylic acids Can be removed, which is effective to increase the stability of the cellulose acylate resin.

(Stabilization)
Cellulose acylate resin after washing with hot water treatment is weakly alkaline (for example, carbonates such as sodium, potassium, calcium, magnesium, aluminum, hydrogen carbonate, etc.) in order to further improve the stability or reduce the carboxylic acid odor. It is also preferable to perform the stabilization treatment with an aqueous solution of a salt, hydroxide, oxide or the like).
Further, the amount of residual impurities in the cellulose acylate resin can be controlled by the amount of the cleaning liquid, the cleaning temperature, the time, the stirring method, the configuration of the cleaning container, the composition and concentration of the stabilizer. In the present invention, it is preferable to set the conditions for acylation, partial hydrolysis and washing so that the amount of residual sulfate radical (as the sulfur atom content) is 0 to 500 ppm.

(Dry)
In the present invention, in order to adjust the water content of the cellulose acylate resin to a preferable amount, it is preferable to dry the cellulose acylate resin. The drying method is not particularly limited as long as the desired moisture content can be obtained. However, it is preferable that the drying method be performed efficiently by using means such as heating, air blowing, decompression, and stirring alone or in combination. At this time, the drying temperature is preferably 0 to 200 ° C, more preferably 40 to 180 ° C, and particularly preferably 50 to 160 ° C. The cellulose acylate resin preferably has a moisture content of 2% by mass or less, more preferably 1% by mass or less, and particularly preferably 0.7% by mass or less.

(Form)
The cellulose acylate resin can take various shapes such as particles, powders, fibers, and lumps, but the raw material for film production is preferably particles or powders. For this reason, the cellulose acylate resin after drying may be pulverized or sieved in order to make the particle size uniform and improve the handleability. When the cellulose acylate is in the form of particles, 90% by mass or more of the particles used preferably have a particle size of 0.5 to 5 mm. Moreover, it is preferable that 50 mass% or more of the particle | grains to be used have a particle size of 1-4 mm. The cellulose acylate particles preferably have a shape as close to a sphere as possible. The cellulose acylate particles preferably have an apparent density of 0.5 to 1.3, more preferably 0.7 to 1.2, and particularly preferably 0.8 to 1.15. The method for measuring the apparent density is defined in JIS K7365 (1999).
The cellulose acylate particles preferably have an angle of repose of 10 to 70 °, more preferably 15 to 60 °, and particularly preferably 20 to 50 °.

(Degree of polymerization)
The number average polymerization degree of the cellulose acylate resin preferably used in the present invention is 110 to 270, preferably 120 to 260, and more preferably 140 to 250. In the present invention, the number average degree of polymerization is measured by a method using gel permeation chromatography (GPC) described later.
In the present invention, the weight average polymerization degree / number average polymerization degree by GPC of the cellulose acylate resin is preferably 1.6 to 3.6, more preferably 1.7 to 3.3. It is especially preferable that it is .8 to 3.2.
These cellulose acylate resins may be used alone or in combination of two or more. Moreover, what mixed suitably polymer components other than a cellulose acylate resin may be used. The polymer component to be mixed is preferably one having excellent compatibility with the cellulose ester, and the transmittance when formed into a film is 80% or more, more preferably 90% or more, and further preferably 92% or more.

[Additive]
(Plasticizer)
Furthermore, in the present invention, a plasticizer can be added to the cellulose acylate resin. When a plasticizer is added to the cellulose acylate resin, stretching strain is easily reduced. Examples of the plasticizer include alkyl phthalyl alkyl glycolates, phosphoric acid esters and carboxylic acid esters.
Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl ethyl glycolate Ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl glycolate, Butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalyl ester Le glycolate, and the like.
Examples of phosphate esters include triphenyl phosphate, tricresyl phosphate, phenyl diphenyl phosphate, and the like. Furthermore, it is preferable to use the phosphate ester plasticizer described in claims 3 to 7 of JP-T-6-501040.
Examples of carboxylic acid esters include phthalic acid esters such as dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate and diethyl hexyl phthalate, and citrate esters such as acetyl trimethyl citrate, acetyl triethyl citrate and acetyl tributyl citrate. And adipic acid esters such as dimethyl adipate, dibutyl adipate, diisobutyl adipate, bis (2-ethylhexyl) adipate, diisodecyl adipate, and bis (butyl diglycol adipate). In addition, butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, triacetin and the like are preferably used alone or in combination.
These plasticizers are preferably 0% by mass to 20% by mass, more preferably 1% by mass to 20% by mass, and further preferably 2% by mass to 15% by mass with respect to the cellulose acylate film (thermoplastic film). These plasticizers may be used in combination of two or more if necessary.

It is also preferable to add a polyhydric alcohol plasticizer in addition to these plasticizers. The polyhydric alcohol plasticizer that can be specifically used in the present invention has good compatibility with cellulose fatty acid esters, and glycerin ester compounds such as glycerin esters and diglycerin esters in which the thermoplastic effect is remarkable, Examples thereof include polyalkylene glycols such as polyethylene glycol and polypropylene glycol, and compounds in which an acyl group is bonded to a hydroxyl group of polyalkylene glycol.
Specific glycerin esters include glycerin diacetate stearate, glycerin diacetate palmitate, glycerin diacetate myristate, glycerin diacetate laurate, glycerin diacetate caprate, glycerin diacetate nonanate, glycerin diacetate octanoate, Glycerin diacetate heptanoate, glycerol diacetate hexanoate, glycerol diacetate pentanoate, glycerol diacetate oleate, glycerol acetate dicaprate, glycerol acetate dioctanoate, glycerol acetate dioctanoate, glycerol acetate diheptanoate , Glycerol acetate dicaproate, glycerol acetate divalerate, glycerol acetate dibu Glycerol dipropionate caprate, glycerol dipropionate laurate, glycerol dipropionate myristate, glycerol dipropionate palmitate, glycerol dipropionate stearate, glycerol dipropionate oleate, glycerol tributyrate, glycerol tri Examples include but are not limited to pentanoate, glycerin monopalmitate, glycerin monostearate, glycerin distearate, glycerin propionate laurate, glycerin oleate propionate, and these are used alone or in combination. be able to.
Among them, glycerol diacetate caprylate, glycerol diacetate pelargonate, glycerol diacetate caprate, glycerol diacetate laurate, glycerol diacetate myristate, glycerol diacetate palmitate, glycerol diacetate stearate, glycerol diacetate oleate preferable.

Specific examples of diglycerin esters include diglycerin tetraacetate, diglycerin tetrapropionate, diglycerin tetrabutyrate, diglycerin tetravalerate, diglycerin tetrahexanoate, diglycerin tetraheptanoate, diglyceride. Glycerin tetracaprylate, diglycerin tetrapelargonate, diglycerin tetracaprate, diglycerin tetralaurate, diglycerin tetramyristate, diglycerin tetrapalmitate, diglycerin triacetate propionate, diglycerin triacetate butyrate, diglycerin Triacetate valerate, diglycerin triacetate hexanoate, diglycerin triacetate heptanoate, diglycerin triacetate caprylate, Glycerin triacetate pelargonate, diglycerol triacetate caprate, diglycerol triacetate laurate, diglycerol triacetate myristate, diglycerol triacetate palmitate, diglycerol triacetate stearate, diglycerol triacetate oleate, diglycerol diacetate dipropionate, diglycerol Diacetate dibutyrate, diglycerin diacetate divalerate, diglycerin diacetate dihexanoate, diglycerin diacetate diheptanoate, diglycerin diacetate dicaprylate, diglycerin diacetate dipelargonate, diglycerin di Acetate dicaprate, diglycerin diacetate dilaurate, diglycerin diacetate dimisti Diglycerin diacetate dipalmitate, diglyceryl diacetate distearate, diglycerin diacetate dioleate, diglyceryl acetate tripropionate, diglyceryl acetate tributyrate, diglyceryl acetate trivalerate, diglyceryl acetate tri Hexanoate, diglycerol acetate triheptanoate, diglycerol acetate tricaprylate, diglycerol acetate tripelargonate, diglycerol acetate tricaprate, diglycerol acetate trilaurate, diglycerol acetate trimyristate, diglycerol acetate tri Palmitate, Diglycerol acetate tristearate, Diglycerol acetate trioleate, Diglycerol laurate, Jig Examples include, but are not limited to, mixed acid esters of diglycerin such as glycerin stearate, diglycerin caprylate, diglycerin myristate, and diglycerin oleate, and these can be used alone or in combination.
Among these, diglycerin tetraacetate, diglycerin tetrapropionate, diglycerin tetrabutyrate, diglycerin tetracaprylate, and diglycerin tetralaurate are preferable.

Specific examples of the polyalkylene glycol include polyethylene glycol and polypropylene glycol having an average molecular weight of 200 to 1000, but are not limited thereto, and these can be used alone or in combination.
Specific examples of the compound in which an acyl group is bonded to the hydroxyl group of polyalkylene glycol include polyoxyethylene acetate, polyoxyethylene propionate, polyoxyethylene butyrate, polyoxyethylene valerate, polyoxyethylene caproate, Polyoxyethylene heptanoate, polyoxyethylene octanoate, polyoxyethylene nonanate, polyoxyethylene caprate, polyoxyethylene laurate, polyoxyethylene myristate, polyoxyethylene palmitate, polyoxyethylene stearate , Polyoxyethylene oleate, polyoxyethylene linoleate, polyoxypropylene acetate, polyoxypropylene propionate, polyoxypropylene butyrate, polyoxypropylene Valerate, polyoxypropylene caproate, polyoxypropylene heptanoate, polyoxypropylene octanoate, polyoxypropylene nonanoate, polyoxypropylene caprate, polyoxypropylene laurate, polyoxypropylene myristate, polyoxy Examples thereof include propylene palmitate, polyoxypropylene stearate, polyoxypropylene oleate, and polyoxypropylene linoleate, but are not limited thereto, and these can be used alone or in combination.

(Aromatic acylated cellulose acylate)
In the present invention, it is also preferable to use cellulose acylate having a composition satisfying the following formulas (T-1) and (T-2).
Formula (T-1): 2.5 <= A + C <3.0
Formula (T-2): 0.1 ≦ C <2
More preferably, the formula (T-3): 2.6 ≦ A + C <2.95
Formula (T-4): 0.1 ≦ C <1.5
More preferably, the formula (T-3): 2.7 ≦ A + C <2.95
Formula (T-4): 0.1 ≦ C <1.0
It is.
In the formula, A represents the degree of substitution of the acetate group, and C represents a substituted or unsubstituted aromatic acyl group.
Examples of the substituted or unsubstituted aromatic acyl group include groups represented by the following general formula (I).

First, general formula (I) will be described. X is a substituent, and examples of the substituent include a halogen atom, a cyano group, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an acyl group, a carbonamido group, a sulfonamido group, a ureido group, an aralkyl group, and a nitro group. Group, alkoxycarbonyl group, aryloxycarbonyl group, aralkyloxycarbonyl group, carbamoyl group, sulfamoyl group, acyloxy group, alkenyl group, alkynyl group, alkylsulfonyl group, arylsulfonyl group, alkyloxysulfonyl group, aryloxysulfonyl group, alkyl Sulfonyloxy group and aryloxysulfonyl group, —S—R, —NH—CO—OR, —PH—R, —P (—R) ₂ , —PH—O—R, —P (—R) (— O -R), -P (-O-R) ₂ , -PH (= O) -RP (= O) (-R) ₂ , -PH (= O) -O-R, -P (= O) (-R) (-O-R), -P (= O) (-O-R) ₂ , -O-PH (= O) -R, -O- P (═O) (— R) ₂ —O—PH (═O) —O—R, —O—P (═O) (— R) (— O—R), —O—P (═O) (—O—R) ₂ , —NH—PH (═O) —R, —NH—P (═O) (— R) (— O—R), —NH—P (═O) (— O— _{R) 2, -SiH 2 -R,} -SiH (-R) 2, -Si (-R) 3, -O-SiH 2 -R, -O-SiH (-R) 2 and -O-Si (- R) ₃ is included. R is an aliphatic group, an aromatic group or a heterocyclic group. The number of substituents is preferably 1 to 5, more preferably 1 to 4, further preferably 1 to 3, and most preferably 1 or 2. As the substituent, a halogen atom, a cyano group, an alkyl group, an alkoxy group, an aryl group, an aryloxy group, an acyl group, a carbonamido group, a sulfonamide group, and a ureido group are preferable, and a halogen atom, a cyano group, an alkyl group, an alkoxy group Group, aryloxy group, acyl group and carbonamido group are more preferred, halogen atom, cyano group, alkyl group, alkoxy group and aryloxy group are more preferred, and halogen atom, alkyl group and alkoxy group are most preferred.

The halogen atom includes a fluorine atom, a chlorine atom, a bromine atom and an iodine atom.
The alkyl group may have a cyclic structure or a branched structure. The number of carbon atoms in the alkyl group is preferably 1-20, more preferably 1-12, still more preferably 1-6, and most preferably 1-4. When the alkyl group has a substituent, the number including the number of carbon atoms of the substituent is preferably the number of carbon atoms (hereinafter, the same applies to other groups). Examples of the alkyl group include methyl group, ethyl group, propyl group, isopropyl group, butyl group, tert-butyl group, hexyl group, cyclohexyl group, octyl group and 2-ethylhexyl group.
The alkoxy group may have a cyclic structure or a branch. The number of carbon atoms in the alkoxy group is preferably 1-20, more preferably 1-12, still more preferably 1-6, and most preferably 1-4. The alkoxy group may be further substituted with another alkoxy group. Examples of the alkoxy group include methoxy group, ethoxy group, 2-methoxyethoxy group, 2-methoxy-2-ethoxyethoxy group, butyloxy group, hexyloxy group and octyloxy group.

The number of carbon atoms of the aryl group is preferably 6-20, and more preferably 6-12. Examples of the aryl group include a phenyl group and a naphthyl group. The aryloxy group preferably has 6 to 20 carbon atoms, more preferably 6 to 12 carbon atoms.
Examples of the aryloxy group include a phenoxy group and a naphthoxy group. The number of carbon atoms in the acyl group is preferably 1-20, and more preferably 1-12.
Examples of the acyl group include a formyl group, an acetyl group, and a benzoyl group.
The carbon atom number of the carbonamide group is preferably 1-20, and more preferably 1-12. Examples of the carbonamido group include an acetamide group and a benzamide group. The number of carbon atoms in the sulfonamide group is preferably 1-20, and more preferably 1-12.
Examples of the sulfonamide group include a methanesulfonamide group, a benzenesulfonamide group, and a p-toluenesulfonamide group.
The number of carbon atoms in the ureido group is preferably 1-20, and more preferably 1-12. Examples of ureido groups include (unsubstituted) ureido groups.

The number of carbon atoms in the aralkyl group is preferably 7-20, and more preferably 7-12. Examples of the aralkyl group include a benzyl group, a phenethyl group, and a naphthylmethyl group. The number of carbon atoms in the alkoxycarbonyl group is preferably 1-20, and more preferably 2-12.
Examples of the alkoxycarbonyl group include a methoxycarbonyl group. The number of carbon atoms of the aryloxycarbonyl group is preferably 7-20, and more preferably 7-12. Examples of the aryloxycarbonyl group include a phenoxycarbonyl group. The number of carbon atoms in the aralkyloxycarbonyl group is preferably 8-20, and more preferably 8-12. Examples of the aralkyloxycarbonyl group include a benzyloxycarbonyl group. The number of carbon atoms of the carbamoyl group is preferably 1-20, and more preferably 1-12. Examples of the carbamoyl group include a (unsubstituted) carbamoyl group and an N-methylcarbamoyl group. The number of carbon atoms in the sulfamoyl group is preferably 20 or less, and more preferably 12 or less. Examples of the sulfamoyl group include a (unsubstituted) sulfamoyl group and an N-methylsulfamoyl group.
The number of carbon atoms in the acyloxy group is preferably 1-20, and more preferably 2-12. Examples of the acyloxy group include an acetoxy group and a benzoyloxy group.

The alkenyl group has preferably 2 to 20 carbon atoms, and more preferably 2 to 12 carbon atoms. Examples of the alkenyl group include a vinyl group, an allyl group, and an isopropenyl group. The alkynyl group preferably has 2 to 20 carbon atoms, and more preferably 2 to 12 carbon atoms.
Examples of the alkynyl group include a thienyl group. The number of carbon atoms in the alkylsulfonyl group is preferably 1-20, and more preferably 1-12. The number of carbon atoms of the arylsulfonyl group is preferably 6-20, and more preferably 6-12.
The number of carbon atoms in the alkyloxysulfonyl group is preferably 1-20, and more preferably 1-12.
The number of carbon atoms of the aryloxysulfonyl group is preferably 6-20, and more preferably 6-12.
The number of carbon atoms of the alkylsulfonyloxy group is preferably 1-20, and more preferably 1-12. The number of carbon atoms of the aryloxysulfonyl group is preferably 6-20, and more preferably 6-12.

  Such compounds are obtained by substituting an aromatic acyl group for the hydroxyl group of cellulose and generally use symmetric acid anhydrides and mixed acid anhydrides derived from aromatic carboxylic acid claloids or aromatic carboxylic acids. Methods and the like. Particularly preferred is a method using an acid anhydride derived from an aromatic carboxylic acid (Journal of Applied Polymer Science, Vol. 29, 3981-3990 (1984)). As a method for producing the cellulose mixed acid ester compound of the present invention as the above method, (1) once the cellulose fatty acid monoester or diester is produced, the remaining hydroxyl group is an aromatic acyl represented by the above general formula (I) And (2) a method of reacting a mixed acid anhydride of an aliphatic carboxylic acid and an aromatic carboxylic acid directly with cellulose. In the method (1), a known method can be adopted as the method for producing cellulose fatty acid ester or diester, and the subsequent reaction for further introducing an aromatic acyl group is appropriately determined depending on the kind of the aromatic acyl group. The reaction temperature is preferably 0 to 100 ° C., more preferably 20 to 50 ° C., and the reaction time is preferably 30 minutes or more, more preferably 30 to 300 minutes. In the method using the mixed acid anhydride (2), the reaction conditions can be appropriately determined depending on the type of the mixed acid anhydride, but the reaction temperature is preferably 0 to 100 ° C., more preferably 20 to 50. C. and the reaction time are preferably 30 to 300 minutes, more preferably 60 to 200 minutes. In any of the above reactions, the reaction may be carried out either without a solvent or in a solvent, but is preferably carried out using a solvent. As the solvent, dichloromethane, chloroform, dioxane and the like can be used.

Specific examples of the aromatic acyl group represented by the general formula (I) are shown below, but the present invention is not limited thereto.

  Among these substituents, the substituents of 1 to 9, 18 to 19, and 27 to 28 are preferable, more preferably 1 to 3 substituents, and most preferably 1 substituent.

(Stabilizer)
In the present invention, it is preferable to use either or both of a phosphite compound and a phosphite compound as a stabilizer. The blending amount of these stabilizers is preferably 0.005 to 0.5% by mass, more preferably 0.01 to 0.4% by mass, and still more preferably 0.02 to 0.3% by mass. %.

(I) Phosphite stabilizer Although a specific phosphite stabilizer is not specifically limited, The phosphite stabilizer shown by following General formula (2)-(4) is preferable.

(Where R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ′ ¹ , R ′ ² , R ′ ³ ... R ′ ^p , R ′ ^{p + 1} are hydrogen or carbon A group selected from the group consisting of alkyl, aryl, alkoxyalkyl, aryloxyalkyl, alkoxyaryl, arylalkyl, alkylaryl, polyaryloxyalkyl, polyalkoxyalkyl and polyalkoxyaryl groups of formulas 4 to 23. In the general formulas (2), (3), and (4), all of them are not hydrogen, and X in the phosphite stabilizer represented by the general formula (3) is an aliphatic chain. And a group selected from the group consisting of an aliphatic chain having an aromatic nucleus in the side chain, an aliphatic chain having an aromatic nucleus in the chain, and a chain including two or more non-continuous oxygen atoms in the chain. , K, q are integers greater than or equal to 1, p is 3 It represents an integer of the above.)

  The numbers of k and q in these phosphite stabilizers are preferably 1 to 10. By setting the number of k and q to 1 or more, volatility at the time of heating is reduced, and setting to 10 or less is preferable because compatibility with cellulose acetate propionate is improved. The value of p is preferably 3-10. By setting it to 3 or more, volatility at the time of heating becomes small, and setting it to 10 or less is preferable because compatibility with cellulose acetate propionate is improved.

  As a specific example of the phosphite stabilizer represented by the following general formula (2), those represented by the following general formulas (5) to (8) are preferable.

  Moreover, as a specific example of the phosphite stabilizer represented by the following general formula (3), those represented by the following general formulas (9) to (11) are preferable.

(Ii) Phosphite ester stabilizer Examples of the phosphite ester stabilizer include cyclic neopentanetetraylbis (octadecyl) phosphite, cyclic neopentanetetraylbis (2,4-di-tert-). Butylphenyl) phosphite, cyclic neopentanetetraylbis (2,6-di-tert-butyl-4-methylphenyl) phosphite, 2,2-methylenebis (4,6-di-tert-butylphenyl) octyl Examples thereof include phosphite and tris (2,4-di-tert-butylphenyl) phosphite.

(Iii) Other stabilizers In addition, weak organic acids, thioether compounds, epoxy compounds and the like may be added as stabilizers.

The weak organic acid is not particularly limited as long as it has a pKa of 1 or more, does not interfere with the action of the present invention, and has coloration prevention properties and physical property deterioration prevention properties. Examples thereof include tartaric acid, citric acid, malic acid, fumaric acid, oxalic acid, succinic acid, maleic acid and the like. These may be used alone or in combination of two or more.
Examples of the thioether compound include dilauryl thiodipropionate, ditridecyl thiodipropionate, dimyristyl thiodipropionate, distearyl thiodipropionate, and palmityl stearyl thiodipropionate. It may be used in combination, or two or more may be used in combination.
Examples of the epoxy compound include those derived from epichlorohydrin and bisphenol A, such as derivatives from epichlorohydrin and glycerin, vinylcyclohexene dioxide, and 3,4-epoxy-6-methylcyclohexylmethyl-3. Cyclic ones such as 1,4-epoxy-6-methylcyclohexanecarboxylate can also be used. Epoxidized soybean oil, epoxidized castor oil, long chain α-olefin oxides, and the like can also be used. These may be used alone or in combination of two or more.

(Matting agent)
Further, it is preferable to add fine particles as a matting agent to the cellulose acylate resin. The fine particles used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate and Mention may be made of calcium phosphate.
These fine particles usually form secondary particles having an average particle size of 0.1 to 3.0 μm, and these fine particles exist in the film as aggregates of primary particles, and 0.1 to 0.1 μm on the film surface. An unevenness of 3.0 μm is formed. The secondary average particle size is preferably 0.2 μm to 1.5 μm, more preferably 0.4 μm to 1.2 μm, and most preferably 0.6 μm to 1.1 μm. For the primary and secondary particle sizes, the particles in the film were observed with a scanning electron microscope, and the diameter of a circle circumscribing the particles was defined as the particle size. In addition, 200 particles were observed at different locations, and the average value was taken as the average particle size.
The amount of the fine particles is preferably 1 ppm to 5000 ppm, more preferably 5 ppm to 1000 ppm, and still more preferably 10 ppm to 500 ppm by mass ratio with respect to the cellulose acylate resin.
Fine particles containing silicon are preferable because they can reduce turbidity, and silicon dioxide is particularly preferable. The fine particles of silicon dioxide preferably have a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / liter or more. Those having an average primary particle size as small as 5 to 16 nm are more preferred because they can reduce the haze of the film. The apparent specific gravity is preferably 90 to 200 g / liter or more, and more preferably 100 to 200 g / liter or more. A larger apparent specific gravity is preferable because a high-concentration dispersion can be produced, and haze and aggregates are improved.

As fine particles of silicon dioxide, for example, commercially available products such as Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (above Nippon Aerosil Co., Ltd.) can be used. Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.), and these can be used.
Among the above-mentioned fine particles, Aerosil 200V and Aerosil R972V are silicon dioxide fine particles having a primary average particle size of 20 nm or less and an apparent specific gravity of 70 g / liter or more, and keep the turbidity of the optical film low. However, since the effect of reducing the friction coefficient is great, it is particularly preferable.

(Other additives)
In addition, an infrared absorbent, an ultraviolet absorbent optical modifier, a surfactant, an odor trapping agent (such as amine), and the like can be added to the cellulose acylate resin. These details are disclosed in the Invention Association Public Technique No. 2001-1745 (issued March 15, 2001, Invention Association), p. Materials described in detail in 17-22 are preferably used.
As the infrared absorbing dye, for example, those disclosed in JP-A No. 2001-194522 can be used, and as the ultraviolet absorber, for example, those described in JP-A No. 2001-151901 can be used. The infrared absorber and the ultraviolet absorber are each 0.001 with respect to the cellulose acylate resin.
It is preferable to contain -5 mass%.

  Examples of the optical adjusting agent include retardation adjusting agents, for example, those described in JP-A Nos. 2001-166144, 2003-344655, 2003-248117, and 2003-66230. Accordingly, 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.

<Saturated norbornene resin>
In the present invention, it is also preferable to use a saturated norbornene resin as the thermoplastic resin of the thermoplastic film. As the saturated norbornene resin, any of the following saturated norbornene resin A and saturated norbornene resin B can be preferably used.

(Saturated norbornene resin A)
As the saturated norbornene resin-A used in the present invention, for example, (1) a ring-opening (co) polymer of a norbornene monomer was modified with a polymer such as maleic acid addition or cyclopentadiene addition as necessary. Later, hydrogenated resins, (2) resins obtained by addition polymerization of norbornene monomers, and (3) resins obtained by addition copolymerization of norbornene monomers and olefin monomers such as ethylene and α-olefin, etc. be able to. The polymerization method and the hydrogenation method can be performed by conventional methods.

  Examples of the norbornene-based monomer include norbornene and alkyl and / or alkylidene substituted products thereof such as 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, and 5-butyl. 2-Norbornene, 5-ethylidene-2-norbornene, and the like, polar substituents such as halogens thereof; dicyclopentadiene, 2,3-dihydrodicyclopentadiene, etc .; dimethanooctahydronaphthalene, its alkyl and / or alkylidene Substituents and polar group substituents such as halogen such as 6-methyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6- Ethyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-oct Hydronaphthalene, 6-ethylidene-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-chloro-1,4: 5,8-dimethano -1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-cyano-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a -Octahydronaphthalene, 6-pyridyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4: 5 8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, etc .; adducts of cyclopentadiene and tetrahydroindene, etc .; 3-pentamers of cyclopentadiene, such as 4,9 : 5,8-dimethano-3a, 4,4a, , 8,8a, 9,9a-octahydro-1H-benzoindene, 4,11: 5,10: 6,9-trimethano-3a, 4,4a, 5,5a, 6,9,9a, 10,10a, 11,11a-dodecahydro-1H-cyclopentanthracene; and the like.

(Saturated norbornene resin-B)
Moreover, as saturated norbornene resin-B, what is represented by the following general formula (1)-(4) can be mentioned, Among these, what is represented by the following general formula (1) is especially preferable.

[In General Formulas (1) to (4), A, B, C and D represent a hydrogen atom or a monovalent organic group, and at least one of them represents a polar group. ]

The weight average molecular weight of these saturated norbornene resins is usually preferably 5,000 to 1,000,000, more preferably 8,000 to 200,000.
Examples of the saturated norbornene resin include, for example, JP-A-60-168708, JP-A-62-252406, JP-A-62-2252407, JP-A-2-133413, JP-A-63-3. Examples thereof include resins described in JP-A No. 145324, JP-A-63-264626, JP-A-1-240517, JP-B-57-8815, and the like.
Among these resins, a hydrogenated polymer obtained by hydrogenating a ring-opening polymer of a norbornene monomer is particularly preferable.
The glass transition temperature (Tg) of these saturated norbornene resins is preferably 120 ° C. or higher, more preferably 140 ° C. or higher, and the saturated water absorption is preferably 1% by mass or lower, more preferably 0.8%. 8 mass% or less. The glass transition temperature (Tg) and saturated water absorption of the saturated norbornene resins represented by the general formulas (1) to (4) can be controlled by selecting the type of the substituents A, B, C, and D. .

  As the saturated norbornene resin, at least one tetracyclododecene derivative represented by the following general formula (5) alone or an unsaturated cyclic compound that can be copolymerized with the tetracyclododecene derivative A hydrogenated polymer obtained by hydrogenating a polymer obtained by metathesis polymerization may be used.

（式中、Ａ、Ｂ、ＣおよびＤは、水素原子または１価の有機基を示し、これらのうち少なくとも１つは極性基である。）

(In the formula, A, B, C and D represent a hydrogen atom or a monovalent organic group, and at least one of them is a polar group.)

In the tetracyclododecene derivative represented by the general formula (5), when at least one of A, B, C and D is a polar group, the polarized light has excellent adhesion to other materials, heat resistance, etc. A film can be obtained. Further, the polar group is a group represented by — (CH ₂ ) n COOR (where R is a hydrocarbon group having 1 to 20 carbon atoms, and n is an integer of 0 to 10). The resulting hydrogenated polymer (polarizing film substrate) is preferred because it has a high glass transition temperature. In particular, the - (CH ₂₎ a polar substituent represented by n COOR the general formula (5) per molecule of the tetracyclododecene derivative be contained one from the viewpoint of reducing the water absorption. In the polar substituent, it is preferable in that the hygroscopicity of the obtained hydrogenated polymer decreases as the number of carbon atoms of the hydrocarbon group represented by R increases, but the balance with the glass transition temperature of the obtained hydrogenated polymer is reduced. From this point, the hydrocarbon group is preferably a chain alkyl group having 1 to 4 carbon atoms or a (poly) cyclic alkyl group having 5 or more carbon atoms, and particularly preferably a methyl group, an ethyl group, or a cyclohexyl group. preferable.

Furthermore, the tetracyclododecene derivative of the general formula (5) in which a hydrocarbon group having 1 to 10 carbon atoms is bonded as a substituent to a carbon atom to which a group represented by — (CH ₂ ) n COOR is bonded, This is preferable because the resulting hydrogenated polymer has low hygroscopicity. In particular, the tetracyclododecene derivative of the general formula (5) in which the substituent is a methyl group or an ethyl group is preferable in terms of easy synthesis. Specifically, 8-methyl-8-methoxycarbonyltetracyclo [4,4,0,12.5,17.10] dodec-3-ene is preferable. These tetracyclododecene derivatives and mixtures of unsaturated cyclic compounds copolymerizable therewith are described, for example, in JP-A-4-77520, page 4, upper right column, line 12 to page 6, lower right column, line 6. Metathesis polymerization and hydrogenation can be carried out by the prepared method.

These norbornene resins preferably have an intrinsic viscosity (ηinh) measured at 30 ° C. in chloroform of 0.1 to 1.5 dl / g, more preferably 0.4 to 1.2 dl / g. It is. Moreover, as a hydrogenation rate of a hydrogenated polymer, the value measured by 60 MHz and < ¹ > H-NMR shall be 50% or more, Preferably it is 90% or more, More preferably, it is 98% or more. The higher the hydrogenation rate, the more the saturated norbornene film obtained has better stability to heat and light. The gel content contained in the hydrogenated polymer is preferably 5% by mass or less, and more preferably 1% by mass or less.

Furthermore, a saturated norbornene resin having the following structure can be used for the film of the present invention. In the present invention, as saturated norbornene resin,
[A-1]: Hydrogenated random copolymer of an α-olefin having 2 to 20 carbon atoms and a cyclic olefin represented by the following formula (II),
[A-2]: A ring-opened polymer of a cyclic olefin represented by the following formula (II) or a hydrogenated product of a copolymer.

Formula (II)

  These saturated norbornene resins have a glass transition temperature (Tg) measured by DSC of preferably 70 ° C. or higher, more preferably 70 to 250 ° C., and further preferably 120 to 180 ° C.

  Further, these saturated norbornene resins are amorphous or low crystalline, and the crystallinity measured by X-ray diffraction method is usually 20% or less, preferably 10% or less, more preferably 2%. It is as follows.

  The saturated norbornene resin of the present invention has an intrinsic viscosity [η] measured in decalin at 135 ° C. of usually 0.01 to 20 dl / g, preferably 0.03 to 10 dl / g, and more Preferably it is 0.05-5 dl / g, The melt flow index (MFR) measured by 260 degreeC load 2.16kg according to ASTM D1238 is 0.1-200 g / 10min normally, Preferably it is 1-100 g / 10 minutes, more preferably 5 to 50 g / 10 minutes.

  Furthermore, the softening point of the cyclic olefin-based resin is usually 30 ° C. or higher, preferably 70 ° C. or higher, more preferably 80 to 260 ° C. as the softening point (TMA) measured with a thermal mechanical analyzer.

Details of the structure of the saturated norbornene represented by the above formula (II) will be described.
In the above formula (II), n is 0 or 1, m is 0 or an integer of 1 or more, and q is 0 or 1. In addition, when q is 1, R ^a and R ^b are each independently the atoms or hydrocarbon groups shown below. When q is 0, each bond is bonded to form a 5-membered member. Form a ring.

R ^{1 to} R ¹⁸ and R ^a and R ^b are each independently a hydrogen atom, a halogen atom or a hydrocarbon group. Here, the halogen atom is a fluorine atom, a chlorine atom, a bromine atom or an iodine atom. Moreover, as a hydrocarbon group, a C1-C20 alkyl group, a C3-C15 cycloalkyl group, and an aromatic hydrocarbon group are mentioned. More specifically, examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, an amyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, and an octadecyl group, and the cycloalkyl group includes a cyclohexyl group. Group, and examples of the aromatic hydrocarbon group include a phenyl group and a naphthyl group. These hydrocarbon groups may be substituted with a halogen atom. Furthermore, in the above formula (II), R ^{15 to} R ¹⁸ may be bonded to each other (in cooperation with each other) to form a monocyclic or polycyclic ring, and the monocyclic or polycyclic ring formed in this way The ring may have a double bond.

で示されるビシクロ[2.2.1]-2-ヘプテン（＝ノルボルネン）（上記式中において、１〜７の数字は炭素の位置番号を示す。）および該化合物に炭化水素基が置換した誘導体が挙げられる。 Specific examples of the cyclic olefin represented by the above formula (II) are shown below. As an example,

And bicyclo [2.2.1] -2-heptene (= norbornene) represented by the formula (wherein the numbers 1 to 7 represent carbon position numbers) and derivatives in which a hydrocarbon group is substituted on the compound. It is done.

  As this substituted hydrocarbon group, 5-methyl group, 5,6-dimethyl group, 1-methyl group, 5-ethyl group, 5-n-butyl group, 5-isobutyl group, 7-methyl group, 5-phenyl group , 5-methyl-5-phenyl group, 5-benzyl group, 5-tolyl group, 5-ethylphenyl group, 5-isopropylphenyl group, 5-biphenyl group, 5-β-naphthyl group, 5-α-naphthyl group , 5-anthracenyl group, 5,6-diphenyl group and the like.

  Still other derivatives include cyclopentadiene-acenaphthylene adduct, 1,4-methano-1,4,4a, 9a-tetrahydrofluorene, 1,4-methano-1,4,4a, 5,10,10a-hexahydro. Bicyclo [2.2.1] -2-heptene derivatives such as anthracene can be exemplified.

で示されるテトラシクロ［４．４．０．１^2,5．１^7,10］−３−ドデセン、およびこれに炭化水素基が置換した誘導体が挙げられる。ここで、誘導体に置換される炭化水素基としては、８−メチル基、８−エチル基、８−プロピル基、８−ブチル基、８−イソブチル基、８−ヘキシル基、８−シクロヘキシル基、８−ステアリル基、５，１０−ジメチル基、２，１０−ジメチル基、８，９−ジメチル基、８−エチル−９−メチル基、１１，１２−ジメチル基、２，７，９−トリメチル基、２，７−ジメチル−９−エチル基、９−イソブチル−２，７−ジメチル基、９，１１，１２−トリメチル基、９−エチル−１１，１２−ジメチル基、９−イソブチル−１１，１２−ジメチル基、５，８，９，１０−テトラメチル基、８−エチリデン基、８−エチリデン−９−メチル基、８−エチリデン−９−エチル基、８−エチリデン−９−イソプロピル基、８−エチリデン−９−ブチル基、８−ｎ−プロピリデン基、８−ｎ−プロピリデン−９−メチル基、８−ｎ−プロピリデン−９−エチル基、８−ｎ−プロピリデン−９−イソプロピル基、８−ｎ−プロピリデン−９−ブチル基、８−イソプロピリデン基、８−イソプロピリデン−９−メチル基、８−イソプロピリデン−９−エチル基、８−イソプロピリデン−９−イソプロピル基、８−イソプロピリデン−９−ブチル基、８−クロロ基、８−ブロモ基、８−フルオロ基、８，９−ジクロロ基、８−フェニル基、８−メチル−８−フェニル基、８−ベンジル基、８−トリル基、８−エチルフェニル基、８−イソプロピルフェニル基、８，９−ジフェニル基、８−ビフェニル基、８−β−ナフチル基、８−α−ナフチル基、８−アントラセニル基、５，６−ジフェニル基等を例示することができる。 In addition, tricyclo [4.3.0.1 ^2,5 ] -3-decene, 2-methyltricyclo [4.3.0.1 ^2,5 ] -3-decene, 5-methyltricyclo [4 .3.0.1 ^2,5 ] -3-decene and other tricyclo [4.3.0.1 ^2,5 ] -3-decene derivatives, tricyclo [4.4.0.1 ^2,5 ] -3 A tricyclo [4.4.0.1 ^2,5 ] -3-undecene derivative such as undecene, 10-methyltricyclo [4.4.0.1 ^2,5 ] -3-undecene,

Tetracyclo [4.4.0.1 ^2,5 . 1 ^7,10 ] -3-dodecene, and derivatives substituted with a hydrocarbon group. Here, examples of the hydrocarbon group substituted by the derivative include 8-methyl group, 8-ethyl group, 8-propyl group, 8-butyl group, 8-isobutyl group, 8-hexyl group, 8-cyclohexyl group, 8 -Stearyl group, 5,10-dimethyl group, 2,10-dimethyl group, 8,9-dimethyl group, 8-ethyl-9-methyl group, 11,12-dimethyl group, 2,7,9-trimethyl group, 2,7-dimethyl-9-ethyl group, 9-isobutyl-2,7-dimethyl group, 9,11,12-trimethyl group, 9-ethyl-11,12-dimethyl group, 9-isobutyl-11,12- Dimethyl group, 5,8,9,10-tetramethyl group, 8-ethylidene group, 8-ethylidene-9-methyl group, 8-ethylidene-9-ethyl group, 8-ethylidene-9-isopropyl group, 8-ethylidene -9-butyl 8-n-propylidene group, 8-n-propylidene-9-methyl group, 8-n-propylidene-9-ethyl group, 8-n-propylidene-9-isopropyl group, 8-n-propylidene-9-butyl Group, 8-isopropylidene group, 8-isopropylidene-9-methyl group, 8-isopropylidene-9-ethyl group, 8-isopropylidene-9-isopropyl group, 8-isopropylidene-9-butyl group, 8- Chloro group, 8-bromo group, 8-fluoro group, 8,9-dichloro group, 8-phenyl group, 8-methyl-8-phenyl group, 8-benzyl group, 8-tolyl group, 8-ethylphenyl group, Examples include 8-isopropylphenyl group, 8,9-diphenyl group, 8-biphenyl group, 8-β-naphthyl group, 8-α-naphthyl group, 8-anthracenyl group, 5,6-diphenyl group, etc. It can be.

Further, tetracyclo [4.4.0.1 ^2,5 ... Cyclopentadiene-acenaphthylene adduct and cyclopentadiene adduct. 1 ^7,10 ] -3-dodecene derivative, pentacyclo [6.5.1.1 ^3,6 . 0 ^2,7 . 0 ^9,13] -4-pentadecene and its derivatives, pentacyclo [7.4.0.1 ^2,5. 1 ^9,12 . 0 ^8,13] -3-pentadecene and its derivatives, pentacyclo [8.4.0.1 ^2,5. 1 ^9,12 . 0 ^8,13] -3-hexadecene and derivatives thereof, pentacyclo [6.6.1.1 ^{3, 6.} 0 ^2,7 . 0 ^9,14] -4-hexadecene and derivatives thereof, hexacyclo [6.6.1.1 ^{3, 6.} 1 ^10,13 . 0 ^2,7 . 0 ^9,14] -4-heptadecene and its derivatives, heptacyclo [8.7.0.1 ^2,9. 1 ^4,7 . 1 ^11,17 . 0 ^3,8 . 0 ^12,16 ] -5-eicosene and its derivatives, heptacyclo [8.7.0.1 ^3,6 . 1 ^10,17 . 1 ^12,15 . 0 ^2,7 . 0 ^11,16 ] -4-eicosene and its derivatives, heptacyclo [8.8.0.1 ^2,9 . 1 ^4,7 . 1 ^11,18 . 0 ^3,8 . 0 ^12,17 ] -5- ^heneicosene and its derivatives, octacyclo [8.8.0.1 ^2,9 . 1 ^4,7 . 1 ^11,18 . 1 ^13,16 . 0 ^3,8 . 0 ^12,17 ] -5-docosene and derivatives thereof, nonacyclo [10.9.1.1 ^4,7 . 1 ^13,20 . 1 ^15,18 . 0 ^2,10 . 0 ^3,8 . 0 ^12,21 . 0 ^14,19] -5-pentacosene and derivatives thereof.

Specific examples of these saturated norbornene resins are as described above, but more specific structures of these compounds are shown in paragraphs 0032 to 0054 of JP-A-7-145213.
Moreover, about the synthesis method of these saturated norbornene resins, it can carry out with reference to paragraph numbers 0039-0068 of Unexamined-Japanese-Patent No. 2001-114836.

The saturated norbornene resin of the present invention is derived from at least one type of polymer units represented by the following formulas (I) to (VI), or from at least one type of these and the compound represented by the following formula (VII). And cycloolefin (co) polymers composed of the following polymerization units. Here, the ratio of the polymerization unit derived from the compound represented by the formula (VII) in the cycloolefin (co) polymer is 0 to 99 mol%.

式中、Ｒ⁹、Ｒ¹⁰、Ｒ¹¹およびＲ¹²は、それぞれ、水素原子、または、炭素数１〜８のアルキル基、炭素数６〜１８のアリール基等の直鎖または分岐の、飽和または不飽和の、炭素数１〜２０の炭化水素基である。 In the above formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ , R ⁷ and R ⁸ are each a hydrogen atom, a linear or branched alkyl group having 1 to 8 carbon atoms, and the number of carbon atoms C6-C20 hydrocarbon group such as 6-18 aryl group, C7-20 alkylene aryl group, C2-C20 alkenyl group which may be cyclic, saturated, unsaturated or aromatic To form a cyclic group. n is an integer of 0-5.

In the formula, each of R ⁹ , R ¹⁰ , R ^11, and R ¹² is a hydrogen atom, or a linear or branched, saturated or saturated group such as an alkyl group having 1 to 8 carbon atoms or an aryl group having 6 to 18 carbon atoms. An unsaturated hydrocarbon group having 1 to 20 carbon atoms.

  The cycloolefin (co) polymer can be obtained, for example, by ring-opening polymerization of at least one of the monomers having the formulas (I) to (VI) and then hydrogenating the resulting product. it can.

式中、ｎは２〜１０の数である。 Moreover, the cycloolefin (co) polymer which contains the polymer unit derived from the compound represented by a following formula (VIII) in the said polymer 0-45 mol% of the whole is also preferable.

In the formula, n is a number of 2 to 10.

  The proportion of polymerized units derived from cyclic, especially polycyclic olefins, is preferably 3 to 75 mol% of the cycloolefin (co) polymer. The proportion of the polymer units derived from the acyclic olefin is preferably 5 to 80 mol% of the cycloolefin (co) polymer.

  The cycloolefin (co) polymer is preferably a polymer unit derived from one or more polycyclic olefins, in particular a polycyclic olefin represented by formula (I) or formula (III), and the formula ( VII) consisting of polymerized units derived from one or more acyclic olefins represented by VII), in particular α-olefins having 2 to 20 carbon atoms. Preferably, it consists in particular of polymerized units derived from polycyclic olefins of formula (I) or formula (III) and polymerized units derived from acyclic olefins of formula (VII) It is a cycloolefin copolymer. Preferably, a polymer unit derived from a polycyclic monoolefin represented by formula I or formula III, a polymer unit derived from an acyclic monoolefin represented by formula (VII), and at least two Carrying cyclic or acyclic olefins (polyenes) containing double bonds, for example, especially cyclic, preferably polycyclic dienes such as norbornadiene, particularly preferably, for example, alkenyl groups having 2 to 20 carbon atoms It is a three-dimensional polymer consisting of polymerized units derived from polycyclic alkenes such as vinyl norbornene.

  The cycloolefin (co) polymer used in the present invention preferably contains an olefin based on a norbornene structure, particularly preferably norbornene, tetracyclododecene, and optionally vinyl norbornene or norbornadiene. Also preferred are cycloolefins (copolymers) comprising polymerized units derived from α-olefins having for example 2 to 20 carbon atoms, particularly preferably acyclic olefins having terminal double bonds such as ethylene or propylene. ) Polymer. Particularly preferred are norbornene / ethylene copolymers and tetracyclododecene / ethylene copolymers.

  Among the three-dimensional polymers, three-dimensional polymers of norbornene / vinyl norbornene / ethylene, norbornene / norbornadiene / ethylene terpolymer, tetracyclododecene / vinylnorbornene / ethylene terpolymer, and tetracyclododecene / vinyl are particularly preferable. Tetracyclododecene-ethylene three-dimensional polymer. The proportion of polymerized units derived from polyenes, preferably vinyl norbornene or norbornadiene, is 0.1 to 50 mol%, particularly preferably 0.1 to 20 mol%, based on the total structure of the cycloolefin (co) polymer. The ratio of the acyclic monoolefin represented by the formula (VII) is usually 0 to 99 mol%, preferably 5 to 80 mol%. In the said three-dimensional polymer, Preferably it is 0.1-99 mol% of a cycloolefin (co) polymer, More preferably, it is 3-75 mol%.

The cycloolefin (co) polymer used in the present invention is preferably a polymer unit that can be derived from a polycyclic olefin represented by the formula (I) and an acyclic olefin represented by the formula (VII). It contains at least one cycloolefin (co) polymer containing polymerized units that can be derived.
Such cycloolefin (co) polymer can be synthesized according to paragraph numbers 0019 to 0020 of JP-A-10-168201.

  Examples of the saturated norbornene resin include known antioxidants such as 2,6-di-tert-butyl-4-methylphenol, 2,2′-dioxy-3,3′-di-tert-butyl-5, 5′-dimethylphenylmethane, tetrakis [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane, 1,1,3-tris (2-methyl-4-hydroxy-5) -Tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, stearyl-β- (3,5- Di-tert-butyl-4-hydroxyphenyl) propionate, 2,2′-dioxy-3,3′-di-tert-butyl-5,5′-diethylphenylmethane 3,9-bis [1,1-dimethyl-2- [β- (3-tert-butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl], 2,4,8,10-tetraoxspiro [5,5] undecane, tris (2,4-di-tert-butylphenyl) phosphite, cyclic neopentanetetraylbis (2,4-di-tert-butylphenyl) phosphite, cyclic neopentanetetra Irbis (2,6-di-tert-butyl-4-methylphenyl) phosphite, 2,2-methylenebis (4,6-di-tert-butylphenyl) octyl phosphite; UV absorber, eg 2,4 -It can be stabilized by adding dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, etc. Kill. Further, additives such as a lubricant can be added for the purpose of improving processability.

The addition amount of these antioxidants is 0.1-3 mass parts normally with respect to 100 mass parts of saturated norbornene-type resin, Preferably it is 0.2-2 mass parts.
Furthermore, you may add various additives, such as anti-aging agents, such as a phenol type and phosphorus type, an antistatic agent, an ultraviolet absorber, and the above-mentioned easy-to-slip agent, to a saturated norbornene-type resin. In particular, since the liquid crystal is usually deteriorated by ultraviolet rays, it is preferable to add an ultraviolet absorber when other protective measures such as laminating an ultraviolet protective filter are not taken. As the UV absorber, a benzophenone UV absorber, a benzotriazole UV absorber, an acrylonitrile UV absorber, or the like can be used. Among them, a benzophenone UV absorber is preferable, and the addition amount is usually 10 ˜100,000 ppm, preferably 100 to 10,000 ppm. Moreover, when producing a sheet | seat by the solution casting method, in order to make surface roughness small, addition of a leveling agent is preferable. As the leveling agent, for example, a coating leveling agent such as a fluorine-based nonionic surfactant, a special acrylic resin leveling agent, or a silicone leveling agent can be used, and among them, those having good compatibility with a solvent are preferable. The addition amount is usually 5 to 50,000 ppm, preferably 10 to 20,000 ppm.

<Film formation>
In the present invention, the residual solvent is preferably 0.01% by mass or less, more preferably 0% by mass. Residual solvent tends to remain locally, and non-uniformity within the film surface tends to occur. Since such a residual solvent is likely to be generated by solution casting, melt casting is preferred for the thermoplastic film of the present invention.

(Melting film formation)
(I) Pelletization The (transparent) thermoplastic resin and additives are preferably mixed and pelletized prior to melt film formation.
The transparent thermoplastic resin and additive are preferably dried in advance for pelletization, but this can be substituted by using a vented extruder. In the case of drying, a method of heating at 90 ° C. for 8 hours or more in a heating furnace can be used as a drying method, but this is not restrictive. Pelletization can be produced by melting the transparent thermoplastic resin and additives at 150 ° C. to 250 ° C. using a twin-screw kneading extruder and then extruding them into noodles and solidifying them in water. . Alternatively, pelletization may be performed by an underwater cutting method or the like that cuts while being directly extruded from a die after being melted by an extruder.
Any known single-screw extruder, non-meshing counter-rotating twin-screw extruder, meshing-type counter-rotating twin-screw extruder, meshing co-direction as long as the melter kneading is sufficient A rotary twin screw extruder or the like can be used.
The preferred size is the cross-sectional area of 1 mm ² to 300 mm ² of the pellets, is 1mm~30mm is Preferably length, more preferably the cross-sectional area of 2 mm ² 100 mm ^2, the length is 1.5Mm～10mm.

Moreover, when pelletizing, the said additive can also be injected | thrown-in from the raw material input port and vent port in the middle of an extruder.
The number of revolutions of the extruder is preferably 10 rpm to 1000 rpm, more preferably 20 rpm to 700 rpm, and even more preferably 30 rpm to 500 rpm. Accordingly, when the rotational speed is slow, the residence time becomes long, which is not preferable because the molecular weight is lowered due to thermal deterioration or the yellowishness is easily deteriorated. On the other hand, if the rotational speed is too high, molecules are likely to be cut by shearing, which leads to problems such as a decrease in molecular weight and an increase in the generation of cross-linked gel.
The extrusion residence time in pelletization is 10 seconds or more and within 30 minutes, more preferably 15 seconds to 10 minutes, and further preferably 30 seconds to 3 minutes. If sufficient melting is possible, a shorter residence time is preferable in terms of suppressing resin deterioration and yellowing.

(Ii) Drying It is preferable to reduce moisture in the pellets prior to melt film formation. The drying method is often dried using a dehumidifying air dryer, but is not particularly limited as long as the desired moisture content can be obtained (heating, blowing, decompression, stirring, etc. alone or in combination. It is preferably carried out efficiently by use, and more preferably, the drying hopper has a heat insulating structure). The drying temperature is preferably 0 to 200 ° C, more preferably 40 to 180 ° C, and particularly preferably 60 to 150 ° C. When the drying temperature is too low, not only does drying take time, but the moisture content does not fall below the target value, which is not preferable. On the other hand, if the drying temperature is too high, the resin sticks and is not preferable. The amount of drying air used is preferably 20 to 400 m ³ / time, more preferably 50 to 300 m ³ / hour, and particularly preferably 100 to 250 m ³ / hour. If the amount of drying air is small, the drying efficiency is unfavorable. On the other hand, even if the air volume is increased, if the amount is more than a certain amount, further improvement of the drying effect is small and not economical. The dew point of air is preferably 0 to -60 ° C, more preferably -10 to -50 ° C, and particularly preferably -20 to -40 ° C. The drying time is required to be at least 15 minutes, more preferably 1 hour or more, and particularly preferably 2 hours or more. On the other hand, even if the drying time exceeds 50 hours, the effect of further reducing the moisture content is small, and there is a concern about thermal degradation of the resin, so it is not preferable to unnecessarily increase the drying time. The water content of the transparent thermoplastic resin of the present invention is preferably 1.0% by mass or less, more preferably 0.1% by mass or less, and particularly preferably 0.01% by mass or less. .

(Iii) Melt extrusion The above-described transparent thermoplastic resin is supplied into the cylinder through the supply port of the extruder. Inside the cylinder, in order from the supply port side, a supply unit (region A) for quantitatively transporting the transparent thermoplastic resin supplied from the supply port, a compression unit (region B) for melting and kneading and compressing the transparent thermoplastic resin, and melt kneading and compression And a measuring part (area C) for measuring the transparent thermoplastic resin. The resin is preferably dried in order to reduce the water content by the above-mentioned method. However, in order to prevent oxidation of the molten resin by residual oxygen, the inside of the extruder is in an inert (nitrogen or the like) air flow or with a vent. More preferably, it is carried out while evacuating using an extruder. The screw compression ratio of the extruder is set to 2.5 to 4.5, and L / D is set to 20 to 70. Here, the screw compression ratio is expressed by the volume ratio between the supply unit A and the metering unit C, that is, the volume per unit length of the supply unit A ÷ the volume per unit length of the metering unit C. It is calculated using the outer diameter d1 of the shaft, the outer diameter d2 of the screw shaft of the measuring part C, the groove part diameter a1 of the supply part A, and the groove part diameter a2 of the measuring part C. L / D is the ratio of the cylinder length to the cylinder inner diameter. Moreover, extrusion temperature is set to 190-240 degreeC. When the temperature in the extruder exceeds 230 ° C., a cooler may be provided between the extruder and the die.

  If the screw compression ratio is less than 2.5 and is too small, it will not be melted and kneaded sufficiently, undissolved parts will be generated, undissolved foreign matter will easily remain in the transparent thermoplastic film after production, and bubbles will be mixed It becomes easy to do. Thereby, the strength of the transparent thermoplastic film is lowered, or when the film is stretched, the film is easily broken, and the orientation cannot be sufficiently increased. On the other hand, if the screw compression ratio exceeds 4.5, the shear stress is excessively applied and the resin is easily deteriorated due to heat generation, so that the transparent thermoplastic film after production is easily yellowed. On the other hand, when too much shear stress is applied, the molecules are cut, the molecular weight is lowered, and the mechanical strength of the film is lowered. Therefore, the screw compression ratio is preferably in the range of 2.5 to 4.5, more preferably 2 in order to make the transparent thermoplastic film after production difficult to produce a yellowish color, have high film strength, and be difficult to stretch and break. .8 to 4.2, particularly preferably in the range of 3.0 to 4.0.

On the other hand, if L / D is less than 20 and is too small, melting and kneading are insufficient, and undissolved foreign matter is likely to be generated in the transparent thermoplastic film after production as in the case where the compression ratio is small. On the other hand, if L / D exceeds 70 and is too large, the residence time of the transparent thermoplastic resin in the extruder becomes too long, and the resin tends to be deteriorated. In addition, when the residence time is long, the molecules are cut or the molecular weight is lowered, so that the mechanical strength of the transparent thermoplastic film is lowered. Therefore, L / D is preferably in the range of 20 to 70, and more preferably in the range of 22 to 65, in order to make the transparent thermoplastic film after production hardly yellowish and the film strength is strong and further makes it difficult to stretch and break. Especially preferably, it is the range of 24-50.
The extrusion temperature is preferably in the above temperature range. The transparent thermoplastic film thus obtained has characteristic values having a haze of 2.0% or less and a yellow index (YI value) of 10 or less.
Here, the haze is an index indicating whether the extrusion temperature is too low, in other words, an index for knowing some of the undissolved foreign matter remaining in the transparent thermoplastic film after manufacture. If the haze exceeds 2.0%, The strength of the transparent thermoplastic film is reduced and breakage during stretching tends to occur. The yellow index (YI value) is an index for knowing whether the extrusion temperature is too high. If the yellow index (YI value) is 10 or less, there is no problem in terms of yellowness.

In general, single-screw extruders with relatively low equipment costs are often used as the types of extruders, and there are screw types such as full flight, madok, and dalmage, but cellulose acid with relatively poor thermal stability. The rate resin is preferably a full flight type. In addition, although the equipment cost is effective, it is possible to use a twin-screw extruder that can be extruded while devolatilizing unnecessary volatile components by providing a vent port in the middle by changing the screw segment. There are two types of shaft extruders, the same direction and different directions, which can be used. However, the type of the same direction rotation is preferred because it is less likely to cause a stagnant portion. The twin-screw extruder is effective in equipment, but has high kneadability and high resin supply performance, so that it can be extruded at low temperatures, and is suitable for film formation of cellulose acetate resin that is easily thermally decomposed. By appropriately arranging the vent opening, it is possible to use the cellulose acylate pellets and powder in an undried state as they are. In addition, film smears produced during film formation can be reused as they are without drying.
In addition, although the diameter of a preferable screw changes with the target extrusion amount per unit time, it is 10 mm-300 mm, More preferably, it is 20 mm-250 mm, More preferably, it is 30 mm-150 mm.

(Iv) Filtration It is preferable to perform a so-called breaker plate type filtration in which a filter medium is provided at the outlet of the extruder for filtering foreign matter in the resin and avoiding damage to the gear pump due to foreign matter. In order to filter foreign matter with higher accuracy, it is preferable to provide a filtration device incorporating a so-called leaf type disk filter after passing through the gear pump. Filtration can be performed by providing one filtration section, or multistage filtration performed by providing a plurality of places. Although the filtration accuracy of the filter medium is preferably higher, the filtration accuracy is preferably 15 μm to 3 μmm, more preferably 10 μm to 3 μm, from the viewpoint of the pressure resistance of the filter medium and the increase in the filtration pressure due to clogging of the filter medium. In particular, when using a leaf-type disk filter device that finally filters foreign matter, it is preferable to use a filter medium with high filtration accuracy in terms of quality, and it is adjusted by the number of loaded sheets to ensure the suitability of pressure resistance and filter life. Is possible. The type of filter medium is preferably a steel material because it is used under high temperature and high pressure. Among steel materials, stainless steel, steel, etc. are particularly preferable, and stainless steel is particularly preferable in terms of corrosion. . As a configuration of the filter medium, for example, a sintered filter medium formed by sintering metal long fibers or metal powder can be used in addition to a knitted wire, and a sintered filter medium is preferable in terms of filtration accuracy and filter life.

(V) Gear pump In order to improve the thickness accuracy, it is important to reduce the fluctuation of the discharge amount. A gear pump is provided between the extruder and the die, and a certain amount of cellulose acylate resin is supplied from the gear pump. Is effective. A gear pump is accommodated in a state where a pair of gears consisting of a drive gear and a driven gear are engaged with each other, and the drive gear is driven to engage and rotate the two gears so that a melted state is generated from the suction port formed in the housing. Resin is sucked into the cavity, and a certain amount of the resin is discharged from a discharge port formed in the housing. Even if there is a slight fluctuation in the resin pressure at the front end of the extruder, the fluctuation is absorbed by using a gear pump, the fluctuation in the resin pressure downstream of the film forming apparatus becomes very small, and the thickness fluctuation is improved. By using a gear pump, it is possible to keep the fluctuation range of the resin pressure in the die portion 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. In addition, a high-precision gear pump using three or more gears that eliminate the gear pump gear variation is also effective.

Other advantages of using a gear pump are that the pressure at the screw tip can be reduced to form a film, reducing energy consumption, preventing rise in resin temperature, improving transport efficiency, reducing residence time in the extruder, L / D can be expected to be shortened. Also, when using a filter to remove foreign matter, if there is no gear pump, the amount of resin supplied from the screw may fluctuate as the filtration pressure rises. It can be resolved. On the other hand, the disadvantages of gear pumps are that the length of the equipment becomes longer depending on the equipment selection method, the residence time of the resin becomes longer, and the shearing stress of the gear pump section may cause the molecular chain to break. is required.
The preferred residence time of the resin from the supply port through the extruder until it exits the die is 2 minutes to 60 minutes, more preferably 3 minutes to 40 minutes, and even more preferably 4 minutes to 30 minutes. is there.

  Since the polymer flow for bearing circulation in the gear pump becomes worse, the polymer seal in the drive part and bearing part worsens, causing problems such as large fluctuations in metering and liquid feed pressure. A gear pump design (especially clearance) that matches the melt viscosity of the resin is required. In some cases, the staying part of the gear pump causes deterioration of the transparent thermoplastic resin, and therefore a structure with as little staying as possible is preferable. The polymer pipes and adapters that connect the extruder and gear pump or gear pump and die must also be designed with as little stagnation as possible, and in order to stabilize the extrusion pressure of transparent thermoplastic resins with high temperature dependence of melt viscosity. It is preferable to make the temperature fluctuation as small as possible. In general, a band heater with a low equipment cost is often used for heating the polymer tube, but it is more preferable to use an aluminum cast heater with less temperature fluctuation. Further, in the extruder as described above, it is preferable that the barrel of the extruder is heated and melted with a heater divided into 3 to 20.

(Vi) Die The transparent thermoplastic resin is melted by the extruder configured as described above, and the molten resin is continuously sent to the die via a filter and a gear pump as necessary. As long as the die is designed so that the molten resin stays in the die, any type of commonly used T die, fishtail die, and hanger coat die may be used. There is no problem in placing a static mixer for improving the uniformity of the resin temperature immediately before the T die. The clearance of the T-die exit portion is generally 1.0 to 5.0 times the film thickness, preferably 1.2 to 3 times, and more preferably 1.3 to 2 times. When the lip clearance is 1.0 times smaller than the film thickness, it is difficult to obtain a good sheet by film formation. Further, when the lip clearance is larger than 5.0 times the film thickness, the sheet thickness accuracy is lowered, which is not preferable. The die is a very important facility for determining the thickness accuracy of the film, and a die that can control the thickness adjustment severely is preferable. Normally, the thickness can be adjusted at intervals of 40 to 50 mm, but preferably a type capable of adjusting the film thickness at intervals of 35 mm or less, more preferably at intervals of 25 mm or less. Further, in order to improve the uniformity of the film-forming film, it is important to design as little as possible of the temperature unevenness of the die and the flow velocity unevenness in the width direction. An automatic thickness adjustment die that measures the downstream film thickness, calculates the thickness deviation, and feeds back the result to the die thickness adjustment is also effective in reducing the thickness fluctuation in long-term continuous production.
For production of a film, a single-layer film forming apparatus with a low equipment cost is generally used. However, in some cases, a film having two or more types of structures can also be manufactured using a multilayer film forming apparatus in order to provide a functional layer on an outer layer. Is possible. In general, the functional layer is preferably thinly laminated on the surface layer, but the layer ratio is not particularly limited.

(Vii) Casting According to the above method, the molten resin extruded onto the sheet from the die is cooled and solidified on the casting drum to obtain a film. At this time, it is preferable to use a method such as an electrostatic application method, an air knife method, an air chamber method, a vacuum nozzle method, or a touch roll method to increase the adhesion between the casting drum and the melt-extruded sheet. Such an adhesion improving method may be performed on the entire surface of the melt-extruded sheet or a part thereof.

  In the present invention, it is particularly preferable to use the touch roll method at the time of casting. In this method, the melt discharged from the die is sandwiched between a casting drum and a touch roll and solidified by cooling. As a result, the non-uniformity when extruded from the die as described above can be improved. That is, since the touch roll can be made to have a uniform temperature by passing a heating medium inside, the resin can be cooled and solidified at a uniform temperature over the entire width by sandwiching the molten resin, thereby further cooling the resin more uniformly. Each ΔRe and ΔRth generated by the residual strain can be reduced. If the cooling temperature is uneven, distortion occurs partially when it is cooled and solidified. For this reason, by using a touch roll, the melt is rapidly cooled (Tg + 40 ° C.) to shorten the passage time of Tg, and the thickness reduction during this time can be reduced. Furthermore, since the melt is pressed from both sides by the touch roll and the casting drum, the vibration of the melt can be suppressed by disturbance, and the occurrence of the horizontal dump can be reduced.

  The touch roll is usually made of a rigid material, but if it is too rigid, residual strain is likely to occur when the melt from the die is sandwiched between the rolls, further promoting partial strain. For this reason, it is preferable that the material of the touch roll has elasticity. As a result, the excessive surface pressure is absorbed by the deformation of the touch roll and the distortion is suppressed. In order to give elasticity to the roll, it is necessary to make the outer cylinder thickness of the roll thinner than a normal roll, and the outer wall thickness Z is preferably 0.05 mm to 7.0 mm, more preferably 0.2 mm to 5.0 mm. More preferably, it is 0.3 mm-3.5 mm. The touch roll may be installed on a metal shaft and a heat medium (fluid) may be passed between them. An elastic layer is provided between the outer cylinder and the metal shaft, and the heat medium (fluid) is filled between the outer cylinders. Can be raised.

  Thus, since the touch roll has low elasticity, when it is brought into contact with the casting roll, it is elastically deformed into a concave shape by the pressing. Therefore, since the touch roll and the casting roll are in surface contact with the cooling roll, the pressure is dispersed and a low surface pressure can be achieved. For this reason, uniform cooling can be achieved without leaving a residual strain in the film sandwiched therebetween. The linear pressure of the preferred touch roll is 1 kg / cm to 100 kg / cm, more preferably 2 kg / cm to 80 kg / cm, and still more preferably 3 kg / cm to 60 kg / cm. The linear pressure referred to here is a value obtained by dividing the force applied to the touch roll by the width of the discharge port of the die. If the linear pressure is less than the above range, the pressing force of the touch roll is weak and the non-uniformity in the surface cannot be corrected. On the other hand, if the linear pressure exceeds the linear pressure, a uniform linear pressure cannot be applied over the entire width (the roll is bent at both ends or Non-uniformity is likely to increase (linear pressure tends to concentrate in the center).

The surface temperature of the touch roll is preferably set to 60 ° C to 160 ° C, more preferably 70 ° C to 150 ° C, and still more preferably 80 ° C to 140 ° C. Such temperature control can be achieved by passing a temperature-controlled liquid or gas through these rolls.
The touch roll and casting roll preferably have a mirror surface, and the arithmetic average height Ra is 100 nm or less, preferably 50 nm or less, more preferably 25 nm or less. Specifically, for example, JP-A No. 11-314263, JP-A No. 2002-36332, JP-A No. 11-235747, WO 97/28950, JP-A No. 2004-216717, and JP-A No. 2003-2003. No. 145609 can be used.

More preferably, a plurality of casting drums (rolls) are used for gradual cooling (among these, the touch roll is used so as to touch the first casting roll on the most upstream side (the one closer to the die)). ). In general, it is relatively common to use three cooling rolls, but this is not a limitation. The diameter of the roll is preferably 50 mm to 5000 mm, more preferably 100 mm to 2000 mm, and still more preferably 150 mm to 1000 mm. The interval between the plurality of 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. The casting drum is preferably 60 ° C to 160 ° C, more preferably 70 ° C to 150 ° C, still more preferably 80 ° C to 140 ° C.
Then, it peels off from a casting drum, winds up after passing through a nip roll. The winding speed is preferably 10 m / min to 100 m / min, more preferably 15 m / min to 80 m / min, still more preferably 20 m / min to 70 m / min.
The film forming width is 0.7 m to 5 m, more preferably 1 m to 4 m, and still more preferably 1.3 m to 3 m. The thickness of the unstretched film thus obtained is preferably 20 μm to 400 μm, more preferably 25 μm to 300 μm, and still more preferably 30 μm to 200 μm. When using it without extending | stretching especially, 30-100 micrometers is preferable, More preferably, it is 30-60 micrometers. Such a thin film is uniformly cooled in the film thickness direction simultaneously from the cast drum side surface to its opposite surface when the melt (melt) from the die during melt film formation cools and solidifies on the cast drum. Therefore, residual strain hardly remains in the film, and retardation change with time hardly occurs. On the other hand, since the thick film is gradually cooled from the cast drum side having a large heat capacity toward the opposite surface, the heat contraction on the cast drum side is larger than that on the opposite surface and distortion is likely to occur. As a result, the retardation change with time tends to increase.

Further, the casting drum is preferably used for the heat treatment because the method (i) is preferably performed while the unstretched thermoplastic film is conveyed on the roll set to the heat treatment temperature as described above. The surface temperature of the casting drum may be any temperature as long as the resin can be removed from the drum. Tg + 40 ° C.) is preferable. The number of thermal relaxation casting drums combined with the number of temperature cooling drums is generally three, but is not limited thereto.

Then, it peels off from a casting drum, winds up after passing through a nip roll. The winding speed is preferably 10 m / min to 100 m / min, more preferably 15 m / min to 80 m / min, still more preferably 20 m / min to 70 m / min.
The film forming width is 0.7 m to 5 m, more preferably 1 m to 4 m, and still more preferably 1.3 m to 3 m. The thickness of the unstretched film thus obtained is preferably 30 μm to 400 μm, more preferably 40 μm to 300 μm, and still more preferably 50 μm to 200 μm.

It is also preferable to trim both ends before winding. As the trimming cutter, any type of rotary cutter, shear blade, knife, or the like may be used. As for the material, either carbon steel or stainless steel may be used. In general, it is preferable to use a cemented carbide blade or a ceramic blade because the life of the blade is long and the generation of chips is suppressed. 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) at one or both ends before winding. The height of the unevenness due to the thickness increasing process is preferably 1 μm to 200 μm, more preferably 10 μm to 150 μm, and still more preferably 20 μm to 100 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, and still more preferably 5 mm to 20 mm. Extrusion can be performed at room temperature to 300 ° C.

Moreover, it is also preferable from a viewpoint of scratch prevention to attach a lami film at least on one side before winding. The thickness of the laminated film is preferably 5 μm to 200 μm, preferably 10 μm to 150 μm, and preferably 15 μm to 100 μm. The material is not particularly limited, such as polyethylene, polyester, and polypropylene.
A preferable winding tension is 1 kg / m width to 50 kg / width, more preferably 2 kg / m width to 40 kg / width, and further preferably 3 kg / m width to 20 kg / width. When the winding tension is smaller than 1 kg / m width, it is difficult to wind the film uniformly. On the other hand, when the winding tension exceeds 50 kg / width, the film becomes tightly wound, not only the appearance of the winding is deteriorated, but also the bump portion of the film extends due to the creep phenomenon, and the film wave This is not preferable because it causes a cause or residual birefringence due to the elongation of the film. It is preferable that the winding tension is detected by tension control in the middle of the line and wound while being controlled so as to have a constant winding tension. If there is a difference in film temperature depending on the location of the film production line, the length of the film may be slightly different due to thermal expansion. It is necessary to prevent tension.

  The winding tension can be wound at a constant tension by controlling the tension control. However, it is more preferable that the winding tension is tapered to an appropriate winding tension according to the wound diameter. Generally, the tension is gradually reduced as the winding diameter increases, but in some cases, it may be preferable to increase the tension as the winding diameter increases.

<Physical properties of stretched and stretched cellulose acylate film>
<Extension>
The reason why the film of the present invention is easy to stretch is that the film of the present invention has a small apparent activation energy, that is, the position of the polymer main chain can be changed with low tension because the position of the polymer main chain can be changed with small energy. It can be oriented. In addition, since the film produced according to the present invention has small thickness unevenness and uniform tension, occurrence of thickness unevenness in the stretching process can be suppressed.
Therefore, it is preferable that the cellulose acylate film of the present invention is longitudinally stretched and / or laterally stretched. Either one of the longitudinal stretching and the lateral stretching may be performed, or both may be performed. Further, the longitudinal stretching and the lateral stretching may each be performed once, or may be performed a plurality of times, and the longitudinal stretching and the lateral stretching may be performed simultaneously.

The draw ratio in this invention is calculated | required using the following formula | equation.
Elongation ratio (%) = 100 × {(Length after stretching) − (Length before stretching)} / (Length before stretching)

  If the unstretched film of the present invention is used, the film can be stretched with a small distortion in the film, and retardation control can be performed with little color unevenness due to temperature fluctuation. Details of the stretching method will be described below.

Specifically, it is preferable to use the following stretching method.
(1) Longitudinal Stretching Longitudinal stretching can be achieved by installing two pairs of nip rolls and heating the gap between them so that the peripheral speed of the outlet side nip roll is faster than the peripheral speed of the inlet side nip roll. At this time, the expression of retardation (Rth) in the thickness direction can be changed by changing the distance (L) between the nip rolls and the film width (W) before stretching. When L / W (referred to as aspect ratio) exceeds 2 and is 50 or less (long span stretching), Rth can be decreased, and when the aspect ratio is 0.01 to 0.3 (short span stretching), Rth can be increased. These are appropriately used according to the purpose (target value of Rth). Details will be described below.

(1-1) Long span stretching The film is stretched as it is stretched. At this time, the film is reduced in thickness and width to reduce the volume change. At this time, shrinkage in the width direction is limited by friction between the nip roll and the film. For this reason, when the nip roll interval is increased, it is easy to contract in the width direction, and thickness reduction can be suppressed. When the thickness reduction is large, the same effect as that in which the film is compressed in the thickness direction is obtained. On the contrary, when the aspect ratio is large and the thickness reduction is small, Rth hardly appears and low Rth can be realized.
Furthermore, if the aspect ratio is long, the uniformity in the width direction can be improved. This is due to the following reason.
• The film tends to shrink in the width direction as it is stretched. At the central portion in the width direction, both sides thereof also try to contract in the width direction, so that it becomes a tug of war and cannot be contracted freely.
-On the other hand, the film width direction end part is in a tug-of-war state only on one side and can contract relatively freely.
-The difference in shrinkage behavior associated with the stretching between both ends and the central portion becomes stretching unevenness in the width direction.
Due to such non-uniformity between both ends and the center, retardation in the width direction and axial deviation (orientation angle distribution of slow axis) occur. On the other hand, since long span stretching is performed slowly between two long nip rolls, uniformity of these non-uniformities (molecular orientation becomes uniform) proceeds during stretching. On the other hand, in normal longitudinal stretching (aspect ratio = more than 0.3 and less than 2), such homogenization does not occur.

The aspect ratio exceeds 2 and is preferably 50 or less, more preferably 3 to 40, and still more preferably 4 to 20. The stretching temperature is preferably (Tg−5 ° C.) to (Tg + 100) ° C., more preferably (Tg) to (Tg + 50) ° C., and further preferably (Tg + 5) to (Tg + 30) ° C. The draw ratio is preferably 1.05 to 3 times, more preferably 1.05 to 1.7 times, and still more preferably 1.05 to 1.4 times. Such long span stretching may be performed in multiple stages with three or more pairs of nip rolls as long as the longest aspect ratio is within the above range.
Such long span stretching may be performed by heating the film between two pairs of nip rolls separated by a predetermined distance. The heating method is a heater heating method (infrared heater, halogen heater, panel heater, etc. above or below the film). Or heating by radiant heat) or a zone heating method (heating in a zone in which hot air or the like is blown and adjusted to a predetermined temperature) may be used. In the present invention, the zone heating method is preferable from the viewpoint of uniformity of the stretching temperature. At this time, the nip roll may be installed in the stretching zone or out of the zone, but in order to prevent the film and the nip roll from sticking, it is preferably out of the zone. It is also preferable to preheat the film before such stretching, and the preheating temperature in this case is preferably (Tg−80 ° C.) to (Tg + 100 ° C.).

By such stretching, a film having an Re value of preferably 0 to 200 nm, more preferably 10 to 200 nm, and even more preferably 15 to 100 nm is obtained. Further, by such stretching, a film having an Rth value of preferably 30 to 500 nm, more preferably 50 to 400 nm, and still more preferably 70 to 350 nm is obtained. By this stretching method, the ratio of Rth and Re (Rth / Re) can be, for example, 0.4 to 0.6, preferably 0.45 to 0.55. Furthermore, by such stretching, both the Re value and the Rth value can be changed to, for example, 5% or less, preferably 4% or less, more preferably 3% or less.
By such stretching, the ratio of the film width before and after stretching (film width after stretching / film width before stretching) is, for example, 0.5 to 0.9, preferably 0.6 to 0.85, more preferably It can be set to 0.65 to 0.83.

(1-2) Short span stretching The aspect ratio (L / W) is, for example, more than 0.01 and less than 0.3, preferably 0.03 to 0.25, more preferably 0.05 to 0.2. Perform longitudinal stretching (short span stretching). By performing stretching at an aspect ratio (L / W) in such a range, neck-in (shrinkage in the direction orthogonal to stretching accompanying stretching) can be reduced. Although the width and thickness are reduced to compensate for stretching in the stretching direction, such short span stretching suppresses width shrinkage and preferentially reduces the thickness. As a result, the film is compressed in the thickness direction, and the orientation (plane orientation) in the thickness direction proceeds. As a result, the Rth value, which is a measure of the anisotropy in the thickness direction, tends to increase. On the other hand, conventionally, the aspect ratio (L / W) is generally about 1 (0.7 to 1.5). This is usually done by installing a heater for heating between the nip rolls, but if the L / W becomes too large, the film cannot be heated uniformly with the heater, uneven stretching tends to occur, and if the L / W is too small. This is because the heater is difficult to install and cannot be heated sufficiently.
The short span stretching described above can be performed by changing the conveyance speed between two or more pairs of nip rolls, but unlike a normal roll arrangement, the two pairs of nip rolls are slanted (the rotational axes of the front and rear nip rolls are shifted up and down). This can be achieved by arranging.
Accordingly, since a heater for heating cannot be installed between the nip rolls, it is preferable to raise the temperature of the film by flowing a heating medium in the nip rolls. Furthermore, it is also preferable to provide a preheating roll in which a heating medium is flowed inside before the entrance side nip roll, and to heat the film before stretching. The stretching temperature is preferably (Tg-5 ° C) to (Tg + 100) ° C, more preferably (Tg) to (Tg + 50) ° C, still more preferably (Tg + 5) to (Tg + 30) ° C, and a preferable preheating temperature. Is Tg-80 ° C to Tg + 100 ° C.

Here, the long span stretching and the short span stretching will be described in detail.
FIG. 2 is a schematic configuration diagram of the film manufacturing apparatus 10 in the case of manufacturing a thermoplastic film by melt film formation when performing long span stretching.
The film manufacturing apparatus 10 is an apparatus for manufacturing a thermoplastic film F that can be used in a liquid crystal display device or the like. After the pelletized cellulose acylate resin or cycloolefin resin, which is a raw material of the thermoplastic film F, is introduced into the dryer 12 and dried, the pellet is extruded by the extruder 14 and supplied to the filter 18 by the gear pump 16. Next, the foreign matter is filtered by the filter 18 and pushed out from the die 20. Thereafter, the film is sandwiched between the cast drum 28 and the touch roll 24 and passes between the cast drum 28 and the roll 26 to be solidified to form an unstretched film Fa having a predetermined surface roughness. And this unstretched film Fa is supplied to the longitudinal stretch part 30 which performs long span stretching.
In the longitudinal stretching section 30, the unstretched film Fa is stretched in the transport direction between the inlet side nip roll 32 and the outlet side nip roller 34 to obtain a longitudinally stretched film Fb. FIG. 3 is a perspective explanatory view of the longitudinal stretching unit 30, and the longitudinal stretching aspect ratio (L / W) is determined by the distance L between the inlet-side nip roll 32 and the outlet-side nip roller 34 and the inlet-side nip roll 32. And the width W of the outlet side nip roller 34 in the length direction. Next, the longitudinally stretched film Fb is adjusted to a predetermined preheating temperature by passing through the preheating unit 36 and then supplied to the lateral stretching unit 42.
In the laterally stretched portion 42, the longitudinally stretched film Fb is stretched in the width direction orthogonal to the transport direction to form a laterally stretched film Fc. Then, the laterally stretched film Fc is supplied to the heat fixing unit 44 and wound up by the winding unit 46, whereby the thermoplastic film F that is the final product in which the orientation angle and retardation are adjusted is manufactured. The transversely stretched film Fc may be further subjected to heat relaxation treatment after passing through the heat fixing portion 44.

On the other hand, FIG. 4 is a schematic configuration diagram of a film manufacturing apparatus 10a in which a longitudinal stretching unit 30a that performs short span stretching is used instead of the longitudinal stretching unit 30 that performs long span stretching shown in FIGS.
In this film manufacturing apparatus 10a, the unstretched film Fa is preheated to a predetermined temperature by the preheating rolls 33 and 35 and then supplied between the two sets of nip rolls 37 and 39 for longitudinal stretching. In this case, the nip rolls 37 and 39 are disposed in the vicinity of the transport direction of the unstretched film Fa and are disposed so that the height differs by a predetermined distance in the vertical direction. By disposing the nip rolls 37 and 39 in this way, the transport distance of the unstretched film Fa in the longitudinal stretching portion 30a can be secured, and the distance between the mechanisms disposed before and after the longitudinal stretching portion 30a can be shortened. The manufacturing apparatus 10a can be downsized.
FIG. 5 is an explanatory perspective view of the longitudinally stretched portion 30a, and the longitudinal stretch aspect ratio (L / W) is the distance L in the transport direction of the unstretched film Fa nipped by the nip rolls 37 and 39. , And the width W in the length direction of the nip rolls 37 and 39.

(2) Lateral stretching Re and Rth can be adjusted by combining longitudinal stretching and lateral stretching. Either longitudinal stretching or lateral uniaxial stretching may be used, but by combining the stretching in both directions, it is easy to adjust that the orientation in the stretching direction advances and the absolute value of Re increases excessively. Further, by combining the longitudinal stretching and the lateral stretching, there is an advantage that the longitudinal orientation and the lateral orientation are offset and Re can be reduced. Furthermore, since the film is stretched in both the vertical and horizontal directions, the thickness reduction is increased, the plane orientation is advanced, and Rth can be increased.
Either the longitudinal stretching or the lateral stretching may be performed first and may be performed at the same time, but a method of performing lateral stretching after the longitudinal stretching is more preferable. Thereby, an installation can be made compact. Although longitudinal stretching and lateral stretching may be performed independently or continuously, it is more preferable to perform them continuously.
The transverse stretching can be performed using, for example, 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 still more preferably (Tg) to (Tg + 30) ° C. A preferable draw ratio is 1.01 times to 4 times, more preferably 1.03 times to 3.5 times, and still more preferably 1.05 times to 2.5 times. The ratio of transverse stretching to longitudinal stretching (lateral stretching ratio / longitudinal stretching ratio) is preferably 1.1 to 100 or 0.9 to 0.01, more preferably 2 to 60 or 0.5 to 0.017, Preferably it is 4-40 or 0.25-0.025.

Preheating can be performed before such stretching, and heat treatment can be performed after stretching. By adopting such means, 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 treatment may be performed, but it is more preferable to perform both. These preheating and heat treatment are preferably performed by holding with a clip, that is, preferably performed continuously with stretching.
Preheating is preferably performed at a temperature higher than the stretching temperature by 1 ° C to 50 ° C, more preferably 2 ° C to 40 ° C, and even 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 further preferably 10 seconds to 2 minutes.
The heat treatment is preferably performed at a temperature lower than the stretching temperature by 1 ° C to 50 ° C, more preferably 2 ° C to 40 ° C, and even more preferably 3 ° C to 30 ° C. More preferably, the temperature is not more than the stretching temperature and not more than Tg. The preheating time is preferably 1 second to 10 minutes, more preferably 5 seconds to 4 minutes, and further preferably 10 seconds to 2 minutes.
Such preheating and heat treatment can reduce the variation in orientation angle and Re and Rth for the following reasons.
The film is stretched in the width direction and tends to become thin (neck-in) in the orthogonal direction (longitudinal direction).
-For this reason, the film before and after transverse stretching is pulled and stress is generated. However, both ends in the width direction are fixed by chucks and are not easily deformed by stress, and the central portion in the width direction is easily deformed. As a result, the stress caused by the neck-in is deformed into a bow shape and bowing occurs. As a result, in-plane Re and Rth unevenness and distribution of orientation axes occur.
In order to suppress this, if the temperature on the preheating side (before stretching) is increased and the temperature on the heat treatment (after stretching) is lowered, neck-in occurs on the high temperature side (preheating) with a lower elastic modulus, and heat treatment ( It becomes difficult to occur after stretching). That is, when heat setting is not performed, as shown in FIG. 6, a convex bowing is generated on the upstream side in the conveyance direction near the exit of the transverse stretching zone of the film F after transverse stretching. By performing heat fixing in the heat fixing part 44 immediately after the extending part 42, as shown in FIG. 7, it is possible to suppress the occurrence of bowing that is convex on the upstream side in the transport direction. Further, when preheating is performed in the preheating section 36 immediately before the lateral stretching section 42, the resin distribution easily spreads in the transport direction downstream near the entrance of the lateral stretching section 42, and uniform lateral stretching becomes possible. Convex bowing hardly occurs on the upstream side in the transport direction near the exit of the laterally extending portion 42. As a result, bowing after stretching can be suppressed.

  By such stretching, the fluctuations of Re and Rth depending on the location in the width direction and the longitudinal direction are both preferably 5% or less, more preferably 4% or less, and still more preferably 3% or less. Further, the orientation angle is preferably 90 ° ± 5 ° or less or 0 ° ± 5 ° or less, more preferably 90 ° ± 3 ° or less or 0 ° ± 3 ° or less, and 90 ° ± 1 ° or less. Or it is more preferable to set it as 0 degrees ± 1 degrees or less.

(3) Relaxation Further, dimensional stability can be improved by performing a relaxation treatment after the stretching. The thermal relaxation is preferably performed after longitudinal stretching, either after lateral stretching, or both, and more preferably after lateral stretching. The relaxation treatment may be performed online continuously after stretching, or may be performed offline after winding after stretching.
The thermal relaxation is preferably (Tg-50) ° C to (Tg + 30) ° C, more preferably (Tg-30) ° C to (Tg + 20) ° C, more preferably (Tg-15) ° C to (Tg + 10) ° C, preferably 1 second to 10 minutes, more preferably 5 seconds to 4 minutes, even more preferably 10 seconds to 2 minutes, preferably 0.1 kg / m to 20 kg / m, more preferably 1 kg / m to 16 kg / m, still more preferably 2 kg It is carried out while transporting at a tension of / m to 12 kg / m.

(4) Physical properties after stretching It is preferable that Re and Rth of the cellulose acylate film thus longitudinally stretched, laterally stretched, and longitudinally and laterally satisfied satisfy the following formulas (R-1) and (R-2).
Formula (R-1): 0 nm ≦ Re ≦ 200 nm
Formula (R-2): 0 nm ≦ Rth ≦ 600 nm
(In the formula, Re represents the in-plane retardation of the thermoplastic film, and Rth represents the thickness direction retardation of the thermoplastic film.)

More preferably, Rth ≧ Re × 1.1
180 ≧ Re ≧ 10
400 ≧ Rth ≧ 50
More preferably, Rth ≧ Re × 1.2
150 ≧ Re ≧ 20
300 ≧ Rth ≧ 100
It is.

  Further, the thermoplastic film produced according to the present invention is considered to have obtained a film with less temperature fluctuations in Re and Rth by stretching the film more uniformly than in the case of stretching a conventional thermoplastic film.

<Processing of thermoplastic film>
The thus obtained (transparent) thermoplastic film may be used alone or in combination with a polarizing plate, and a liquid crystal layer or a layer with a controlled refractive index (low reflection) Layer) or a hard coat layer may be used. These can be achieved by the following steps.

(1) Surface treatment (i) Cellulose acylate film By performing the surface treatment, adhesion with each functional layer (for example, undercoat layer and back layer) can be improved. For example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The “glow discharge treatment” here is a treatment for subjecting the film surface to a plasma treatment in the presence of a plasma-excitable gas.
The glow discharge treatment includes a low temperature plasma treatment that occurs under a low pressure gas of 10 ^{−3 to} 20 Torr (0.13 to 2700 Pa). Further, plasma treatment under atmospheric pressure is also a preferable glow discharge treatment. The plasma-excitable gas refers to a gas that is plasma-excited under the above-described conditions, and includes chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. can give. Details of these are described in detail on pages 30 to 32 in the Journal of the Invention Association (Technology No. 2001-1745, issued on March 15, 2001, Invention Association). Note that, in the plasma treatment at atmospheric pressure which has been attracting attention in recent years, irradiation energy of 20 to 500 kGy is used, for example, under 10 to 1000 Kev, and more preferably irradiation energy of 20 to 300 kGy is used under 30 to 500 Kev.
Of these, alkali saponification is particularly preferable.

  The alkali saponification treatment may be immersed in a saponification solution (immersion method) or a saponification solution may be applied (application method). In the case of the dipping method, it is achieved by passing an aqueous solution of pH 10 to 14 such as NaOH or KOH through a bath heated to 20 ° C. to 80 ° C. for 0.1 minutes to 10 minutes, followed by neutralization, washing with water and drying. it can.

  In the case of the coating method, a dip coating method, a curtain coating method, an extrusion coating method, a bar coating method, and an E-type coating method can be used. The solvent of the alkali saponification coating solution has good wettability because it is applied to the transparent support of the saponification solution, and the surface state remains good without forming irregularities on the surface of the transparent support by the saponification solution solvent. It is preferred to select a solvent to keep. Specifically, an alcohol solvent is preferable, and isopropyl alcohol is particularly preferable. An aqueous solution of a surfactant can also be used as a solvent. The alkali of the alkali saponification coating solution is preferably an alkali that dissolves in the solvent, and more preferably KOH or NaOH. The pH of the saponification coating solution is preferably 10 or more, more preferably 12 or more. The reaction conditions during alkali saponification are preferably 1 second to 5 minutes at room temperature, more preferably 5 seconds to 5 minutes, and particularly preferably 20 seconds to 3 minutes. After the alkali saponification reaction, it is preferable to wash the surface on which the saponification solution is applied with water or with an acid and then with water. Further, the coating-type saponification treatment and the alignment film uncoating described later can be performed continuously, and the number of steps can be reduced. Specific examples of these saponification methods are described in JP 2002-82226 A and WO 02/46809 pamphlet.

It is also preferable to provide an undercoat layer for adhesion to the functional layer. This layer may be coated after the surface treatment or may be coated without the surface treatment. Details of the undercoat layer are described on page 32 of the Japan Society for Invention and Innovation (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention).
These surface treatment and undercoating processes can be incorporated at the end of the film forming process, can be performed alone, or can be performed in the functional layer application process described later.

(Ii) Transparent thermoplastic film other than cellulose acylate A transparent thermoplastic film such as a saturated norbornene film can be subjected to glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment. The glow discharge treatment here is a treatment for subjecting the film surface to a plasma treatment in the presence of a plasma-excitable gas as described above.
The glow discharge treatment includes a low temperature plasma treatment that occurs under a low pressure gas of 10 ^{−3 to} 20 Torr (0.13 to 2700 Pa). Further, plasma treatment under atmospheric pressure is also a preferable glow discharge treatment. The plasma-excitable gas refers to a gas that is plasma-excited under the above-described conditions, and includes chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. can give. Details of these are described in detail on pages 30 to 32 in the Journal of the Invention Association (Technology No. 2001-1745, issued on March 15, 2001, Invention Association). Note that, in the plasma treatment at atmospheric pressure which has been attracting attention in recent years, irradiation energy of 20 to 500 kGy is used, for example, under 10 to 1000 Kev, and more preferably irradiation energy of 20 to 300 kGy is used under 30 to 500 Kev.
Of these, glow discharge treatment, corona treatment, and flame treatment are particularly preferred.

It is also preferable to provide an undercoat layer for adhesion to the functional layer. This layer may be coated after the surface treatment or may be coated without the surface treatment. Details of the undercoat layer are described on page 32 of the Japan Society for Invention and Innovation (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention).
These surface treatment and undercoating processes can be incorporated at the end of the film forming process, can be performed alone, or can be performed in the functional layer application process described later.

(2) Application of functional layer The thermoplastic film of the present invention is described in detail on pages 32 to 45 in the Japan Society for Invention and Innovation Technical Report (Technical Number 2001-1745, published on March 15, 2001, Japan Society for Invention). It is preferable to combine the functional layers. Among these, application of a polarizing film (polarizing plate), application of an optical compensation layer (optical compensation sheet), and application of an antireflection layer (antireflection film) are preferable.

(A) Application of polarizing film (production of polarizing plate)
The polarizing plate of the present invention is characterized by using the thermoplastic film of the present invention. Preferably, at least one sheet of the thermoplastic film of the present invention is used as a polarizing plate protective film.
(E1) Material used Currently, a commercially available polarizing film is produced by immersing a stretched polymer in a solution of iodine or dichroic dye in a bath, and allowing the iodine or dichroic dye to penetrate into the binder. It is common to be done. As the polarizing film, a coating type polarizing film represented by Optiva Inc. can also be used. Iodine and dichroic dye in the polarizing film exhibit deflection performance by being oriented in the binder. As the dichroic dye, an azo dye, stilbene dye, pyrazolone dye, triphenylmethane dye, quinoline dye, oxazine dye, thiazine dye or anthraquinone dye is used. The dichroic dye is preferably water-soluble. The dichroic dye preferably has a hydrophilic substituent (eg, sulfo, amino, hydroxyl). For example, the compound as described in Invention Association public technique, public technical number 2001-1745, page 58 (issue date March 15, 2001) can be mentioned.

  As the binder for the polarizing film, either a polymer that can be crosslinked per se or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of the binder include methacrylate copolymer, styrene copolymer, polyolefin, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylolacrylamide) described in paragraph No. [0022] of JP-A-8-338913. , Polyester, polyimide, vinyl acetate copolymer, carboxymethyl cellulose, polycarbonate and the like. Silane coupling agents can be used as the polymer. Water-soluble polymers (eg, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, modified polyvinyl alcohol) are preferred, gelatin, polyvinyl alcohol and modified polyvinyl alcohol are more preferred, and polyvinyl alcohol and modified polyvinyl alcohol are most preferred. . It is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%. It is preferable that the polymerization degree of polyvinyl alcohol is 100-5000. The modified polyvinyl alcohol is described in JP-A-8-338913, JP-A-9-152509 and JP-A-9-316127. Two or more kinds of polyvinyl alcohol and modified polyvinyl alcohol may be used in combination.

The lower limit of the binder thickness is preferably 10 μm. The upper limit of the thickness is preferably as thin as possible from the viewpoint of light leakage of the liquid crystal display device. It is preferably not more than a commercially available polarizing plate (about 30 μm), preferably 25 μm or less, and more preferably 20 μm or less.
The binder of the polarizing film may be cross-linked. A polymer or monomer having a crosslinkable functional group may be mixed in the binder, or a crosslinkable functional group may be imparted to the binder polymer itself. Crosslinking can be performed by light, heat, or pH change, and a binder having a crosslinked structure can be formed. The crosslinking agent is described in US Reissue Patent 23297. Boron compounds (eg, boric acid, borax) can also be used as a crosslinking agent. The addition amount of the crosslinking agent in the binder is preferably 0.1 to 20% by mass with respect to the binder. The orientation of the polarizing element and the wet heat resistance of the polarizing film are improved.
Even after the crosslinking reaction is completed, the unreacted crosslinking agent is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. By doing in this way, a weather resistance improves.

(E2) Stretching of polarizing film The polarizing film is preferably dyed with iodine or a dichroic dye after the polarizing film is stretched (stretching method) or rubbed (rubbing method).
In the stretching method, the stretching ratio is preferably 2.5 to 30.0 times, and more preferably 3.0 to 10.0 times. Stretching can be performed by dry stretching in air. Moreover, you may implement wet extending | stretching in the state immersed in water. The stretch ratio of dry stretching is preferably 2.5 to 5.0 times, and the stretch ratio of wet stretching is preferably 3.0 to 10.0 times. Stretching may be performed in parallel to the MD direction (parallel stretching) or may be performed in an oblique direction (oblique stretching). These stretching operations may be performed once or divided into several times. By dividing into several times, it is possible to stretch more uniformly even at high magnification.

a) Parallel stretching method Prior to stretching, the PVA film is preferably swollen. The degree of swelling is 1.2 to 2.0 times (mass ratio between before swelling and after swelling). Thereafter, the film is stretched at a bath temperature of 15 to 50 ° C., particularly 17 to 40 ° C. in an aqueous medium bath or a dye bath for dissolving a dichroic substance while being continuously conveyed through a guide roll or the like. Stretching can be achieved by gripping with two pairs of nip rolls and increasing the conveyance speed of the subsequent nip roll to be higher than that of the previous nip roll. The draw ratio is based on the length ratio after stretching / initial state (hereinafter the same), but the preferred draw ratio is 1.2 to 3.5 times, especially 1.5 to 3.0 times from the viewpoint of the above-mentioned effects. is there. Then, it is made to dry at 50 to 90 degreeC, and a polarizing film is obtained.

b) Diagonal Stretching Method For this purpose, a method of stretching using a tenter projecting in an oblique direction inclined in an oblique direction described in JP-A-2002-86554 can be used. Since this stretching is performed in the air, it is necessary to make it easy to stretch by adding water in advance. The preferred water content is 5% to 100%, more preferably 10% to 100%.
The temperature during stretching is preferably 40 ° C to 90 ° C, more preferably 50 ° C to 80 ° C. The humidity is preferably 50% relative humidity to 100% relative humidity, more preferably 70% relative humidity to 100% or less relative humidity, and still more preferably 80% relative humidity to 100% relative humidity. The traveling speed in the longitudinal direction is preferably 1 m / min or more, more preferably 3 m / min or more.
After the completion of stretching, the film is dried at 50 to 100 ° C., more preferably 60 to 90 ° C., for 0.5 to 10 minutes. More preferably, it is 1 minute to 5 minutes.
The absorption axis of the polarizing film thus obtained is preferably 10 ° to 80 °, more preferably 30 ° to 60 °, and still more preferably 45 ° (40 ° to 50 °).

(E3) Bonding The thermoplastic film after the surface treatment and the polarizing film prepared by stretching are bonded to prepare a polarizing plate. The laminating direction is preferably performed so that the casting axis direction of the transparent thermoplastic film and the stretching axis direction of the polarizing plate are 45 °.
The adhesive for bonding is not particularly limited, but examples thereof include PVA resins (including modified PVA such as acetoacetyl group, sulfonic acid group, carboxyl group, oxyalkylene group) and boron compound aqueous solution. preferable. The thickness of the adhesive layer is preferably 0.01 to 10 μm after drying, and particularly preferably 0.05 to 5 μm.
The polarizing plate thus obtained preferably has a higher light transmittance, and preferably has a higher degree of polarization. The transmittance of the polarizing plate is preferably in the range of 30 to 50%, more preferably in the range of 35 to 50%, and most preferably in the range of 40 to 50% in light having a wavelength of 550 nm. . The degree of polarization is preferably in the range of 90 to 100%, more preferably in the range of 95 to 100%, and most preferably in the range of 99 to 100% in light having a wavelength of 550 nm.
Furthermore, the polarizing plate thus obtained can be laminated with a λ / 4 plate to produce circularly polarized light. In this case, lamination is performed so that the slow axis of λ / 4 and the absorption axis of the polarizing plate are 45 °. At this time, λ / 4 is not particularly limited, but more preferably has a wavelength dependency such that the lower the wavelength, the smaller the retardation. Furthermore, it is preferable to use a polarizing film having an absorption axis inclined by 20 ° to 70 ° with respect to the longitudinal direction and a λ / 4 plate made of an optically anisotropic layer made of a liquid crystalline compound.

(B) Application of optical compensation layer (production of optical compensation sheet)
The optical compensation sheet has an optical compensation layer on a substrate, and the thermoplastic film of the present invention can be used as the substrate.
The optically anisotropic layer is for compensating the liquid crystal compound in the liquid crystal cell in the black display of the liquid crystal display device, and forms an alignment film on the transparent thermoplastic film, and further provides an optically anisotropic layer. It is formed by doing.

(B-1) Alignment film An alignment film is provided on the surface-treated transparent thermoplastic film. This film has a function of defining the alignment direction of liquid crystalline molecules. However, if the alignment state is fixed after aligning the liquid crystalline compound, the alignment film plays the role, and thus is not necessarily an essential component of the present invention. That is, it is possible to produce the polarizing plate of the present invention by transferring only the optically anisotropic layer on the alignment film in which the alignment state is fixed onto the polarizer.
The alignment film is an organic compound (eg, ω-tricosanoic acid) formed by rubbing treatment of an organic compound (preferably polymer), oblique deposition of an inorganic compound, formation of a layer having a microgroove, or Langmuir-Blodgett method (LB film). , Dioctadecylmethylammonium chloride, methyl stearylate). Furthermore, an alignment film in which an alignment function is generated by application of an electric field, application of a magnetic field, or light irradiation is also known.

The alignment film is preferably formed by polymer rubbing treatment. In principle, the polymer used for the alignment film has a molecular structure having a function of aligning liquid crystal molecules.
In the present invention, in addition to the function of aligning liquid crystalline molecules, a cross-linking having a function of aligning a side chain having a crosslinkable functional group (eg, double bond) to the main chain or aligning liquid crystalline molecules. It is preferable to introduce a functional functional group into the side chain.

  As the polymer used in the alignment film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of the polymer include methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohol and modified polyvinyl alcohol, poly (N-methylol) described in paragraph No. [0022] of JP-A-8-338913. Acrylamide), polyester, polyimide, vinyl acetate copolymer, carboxymethylcellulose, polycarbonate and the like. Silane coupling agents can be used as the polymer. Water-soluble polymers (eg, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, modified polyvinyl alcohol) are preferred, gelatin, polyvinyl alcohol and modified polyvinyl alcohol are more preferred, and polyvinyl alcohol and modified polyvinyl alcohol are most preferred. . It is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%. It is preferable that the polymerization degree of polyvinyl alcohol is 100-5000.

A side chain having a function of aligning liquid crystal molecules generally has a hydrophobic group as a functional group. The specific type of functional group is determined according to the type of liquid crystal molecule and the required alignment state.
For example, the modifying group of the modified polyvinyl alcohol can be introduced by copolymerization modification, chain transfer modification or block polymerization modification. Examples of modifying groups include hydrophilic groups (carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, amino groups, ammonium groups, amide groups, thiol groups, etc.), hydrocarbon groups having 10 to 100 carbon atoms, fluorine atoms Substituted hydrocarbon groups, thioether groups, polymerizable groups (unsaturated polymerizable groups, epoxy groups, azirinidyl groups, etc.), alkoxysilyl groups (trialkoxy, dialkoxy, monoalkoxy) and the like can be mentioned. As specific examples of these modified polyvinyl alcohol compounds, for example, paragraph numbers [0022] to [0145] in JP-A No. 2000-155216 and paragraph numbers [0018] to [0018] in JP-A No. 2002-62426 are described. [0022] and the like.

  When a side chain having a crosslinkable functional group is bonded to the main chain of the alignment film polymer, or a crosslinkable functional group is introduced into a side chain having a function of aligning liquid crystalline molecules, the alignment film polymer and the optically anisotropic film The polyfunctional monomer contained in the conductive layer can be copolymerized. As a result, not only between the polyfunctional monomer and the polyfunctional monomer, but also between the alignment film polymer and the alignment film polymer and between the polyfunctional monomer and the alignment film polymer is firmly bonded by a covalent bond. Therefore, the strength of the optical compensation sheet can be remarkably improved by introducing the crosslinkable functional group into the alignment film polymer.

  The crosslinkable functional group of the alignment film polymer preferably contains a polymerizable group in the same manner as the polyfunctional monomer. Specific examples include those described in paragraphs [0080] to [0100] in JP-A-2000-155216. Apart from the crosslinkable functional group, the alignment film polymer can also be crosslinked using a crosslinking agent.

Examples of the crosslinking agent include aldehydes, N-methylol compounds, dioxane derivatives, compounds that act by activating carboxyl groups, active vinyl compounds, active halogen compounds, isoxazole, and dialdehyde starch. Two or more kinds of crosslinking agents may be used in combination. Specific examples include compounds described in paragraphs [0023] to [024] in JP-A No. 2002-62426. Aldehydes having high reaction activity, particularly glutaraldehyde are preferred.
0.1-20 mass% is preferable with respect to a polymer, and, as for the addition amount of a crosslinking agent, 0.5-15 mass% is more preferable. The amount of the unreacted crosslinking agent remaining in the alignment film is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. By adjusting in this way, even if the alignment film is used for a long time in a liquid crystal display device or left in a high temperature and high humidity atmosphere for a long time, sufficient durability without reticulation can be obtained. May occur.

  The alignment film can be basically formed by applying the polymer, which is an alignment film forming material, on a transparent support containing a crosslinking agent, followed by heat drying (crosslinking) and rubbing treatment. As described above, the crosslinking reaction may be performed at any time after coating on the transparent support. When a water-soluble polymer such as polyvinyl alcohol is used as the alignment film forming material, the coating solution is preferably a mixed solvent of an organic solvent (eg, methanol) having a defoaming action and water. The ratio of water: methanol is preferably 0: 100 to 99: 1, and more preferably 0: 100 to 91: 9. Thereby, generation | occurrence | production of a bubble is suppressed and the defect of the layer surface of an alignment film and also an optical anisotropic layer reduces remarkably.

The alignment film is preferably applied by spin coating, dip coating, curtain coating, extrusion coating, rod coating, or roll coating. A rod coating method is particularly preferable. The film thickness after drying is preferably 0.1 to 10 μm. Heating and drying can be performed at 20 ° C to 110 ° C. In order to form sufficient cross-linking, 60 ° C to 100 ° C is preferable, and 80 ° C to 100 ° C is particularly preferable. The drying time can be 1 minute to 36 hours, preferably 1 minute to 30 minutes. The pH is preferably set to an optimum value for the crosslinking agent to be used. When glutaraldehyde is used, the pH is 4.5 to 5.5, and 5 is particularly preferable.
The alignment film is provided on the transparent support or the undercoat layer. The alignment film can be obtained by rubbing the surface after crosslinking the polymer layer as described above.
For the rubbing treatment, a treatment method widely adopted as a liquid crystal alignment treatment process of LCD can be applied. That is, a method of obtaining the orientation by rubbing the surface of the orientation film in a certain direction using paper, gauze, felt, rubber, nylon, polyester fiber or the like can be used. Generally, it is carried out by rubbing several times using a cloth or the like in which fibers having a uniform length and thickness are planted on average.

When the industrial rubbing treatment is carried out, it is achieved by bringing the rotating rubbing roll into contact with the film with the polarizing film being conveyed. However, the roundness, cylindricity, and deflection (eccentricity) of the rubbing roll are achieved. ) Is preferably 30 μm or less. The film wrap angle on the rubbing roll is preferably 0.1 to 90 °. However, as described in JP-A-8-160430, a stable rubbing treatment can be obtained by winding 360 ° or more. As for the conveyance speed of a film, 1-100 m / min is preferable. It is preferable to select an appropriate rubbing angle in the range of 0 to 60 °. When used for a liquid crystal display device, 40 to 50 ° is preferable. 45 ° is particularly preferred.
The thickness of the alignment film thus obtained is preferably in the range of 0.1 to 10 μm.

Next, the liquid crystalline molecules of the optically anisotropic layer are aligned on the alignment film. Thereafter, if necessary, the alignment film polymer and the polyfunctional monomer contained in the optically anisotropic layer are reacted, or the alignment film polymer is crosslinked using a crosslinking agent.
The liquid crystalline molecules used in the optically anisotropic layer include rod-like liquid crystalline molecules and discotic liquid crystalline molecules. The rod-like liquid crystal molecules and the disk-like liquid crystal molecules may be high-molecular liquid crystals or low-molecular liquid crystals, and further include those in which low-molecular liquid crystals are cross-linked and no longer exhibit liquid crystallinity.

(B-2) Rod-like liquid crystal molecules The rod-like liquid crystal molecules include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoate esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano. Substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.
The rod-like liquid crystalline molecule includes a metal complex. In addition, a liquid crystal polymer containing a rod-like liquid crystalline molecule in a repeating unit can also be used as the rod-like liquid crystalline molecule. In other words, the rod-like liquid crystal molecule may be bonded to a (liquid crystal) polymer.
For rod-like liquid crystalline molecules, see Chapter 4, Chapter 7 and Chapter 11 of the Chemistry of the Quarterly Chemistry Vol. 22 (1994) The Chemical Society of Japan, and the 142th Committee of the Japan Society for the Promotion of Science. Described in Chapter 3.
The birefringence of the rod-like liquid crystal molecule is preferably in the range of 0.001 to 0.7.
The rod-like liquid crystal molecule preferably has a polymerizable group in order to fix its alignment state. The polymerizable group is preferably a radically polymerizable unsaturated group or a cationically polymerizable group. Specifically, for example, the polymerizable groups described in paragraphs [0064] to [0086] of JP-A-2002-62427 are described. Group and a polymerizable liquid crystal compound.

(B-3) Discotic liquid crystalline molecules The discotic liquid crystalline molecules include C.I. Destrade et al., Mol. Cryst. 71, 111 (1981), benzene derivatives described in C.I. Destrade et al., Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990); Kohne et al., Angew. Chem. 96, page 70 (1984) and the cyclohexane derivatives described in J. Am. M.M. Lehn et al. Chem. Commun. , 1794 (1985), J. Am. Zhang et al., J. Am. Chem. Soc. 116, 2655 (1994), azacrown type and phenylacetylene type macrocycles are included.

As a discotic liquid crystalline molecule, a compound having liquid crystallinity in which a linear alkyl group, an alkoxy group, and a substituted benzoyloxy group are substituted radially as a side chain of the mother nucleus with respect to the mother nucleus at the center of the molecule Is also included. The molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting a certain orientation. In the optically anisotropic layer formed from the discotic liquid crystalline molecules, the compound finally contained in the optically anisotropic layer does not need to be a discotic liquid crystalline molecule. Also included are compounds that have a group that reacts with heat or light, and that eventually polymerize or cross-link by reaction with heat or light to increase the molecular weight and lose liquid crystallinity. Preferred examples of the discotic liquid crystalline molecules are described in JP-A-8-50206. The polymerization of discotic liquid crystalline molecules is described in JP-A-8-27284.
In order to fix the discotic liquid crystalline molecules by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline molecules. A compound in which the discotic core and the polymerizable group are bonded via a linking group is preferable, whereby the orientation state can be maintained even in the polymerization reaction. Examples thereof include compounds described in paragraphs [0151] to “0168” in JP-A No. 2000-155216.

In the hybrid alignment, the angle between the major axis (disk surface) of the discotic liquid crystalline molecule and the surface of the polarizing film increases or decreases in the depth direction of the optically anisotropic layer and with increasing distance from the surface of the polarizing film. is doing. It is preferable that the angle between the major axis of the discotic liquid crystalline molecule and the plane of the polarizing film decreases as the distance increases. Furthermore, as the change of the angle between the major axis of the discotic liquid crystalline molecule and the plane of the polarizing film, the change includes continuous increase, continuous decrease, intermittent increase, intermittent decrease, continuous increase and continuous decrease, Alternatively, intermittent changes including increases and decreases are possible. The intermittent change includes a region where the inclination angle does not change in the middle of the thickness direction. Even if the angle between the major axis of the discotic liquid crystalline molecule and the plane of the polarizing film includes a region where the angle does not change, it may be increased or decreased as a whole. Furthermore, it is preferable that the angle changes continuously.

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

(B-4) Other composition of optically anisotropic layer Along with the above liquid crystalline molecules, a plasticizer, a surfactant, a polymerizable monomer, etc. are used in combination, and the uniformity of the coating film, the strength of the film, and the liquid crystal Molecular orientation and the like can be improved. It is preferable that the compound has compatibility with the liquid crystal molecules and can change the tilt angle of the liquid crystal molecules or does not inhibit the alignment.
Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Preferably, it is a polyfunctional radically polymerizable monomer and is preferably copolymerizable with the polymerizable group-containing liquid crystal compound. Examples thereof include those described in paragraph numbers [0018] to [0020] in JP-A No. 2002-296423. The amount of the compound added is generally in the range of 1 to 50% by mass and preferably in the range of 5 to 30% by mass with respect to the discotic liquid crystalline molecules.

Examples of the surfactant include conventionally known compounds, and fluorine compounds are particularly preferable. Specific examples include compounds described in paragraph numbers [0028] to [0056] in JP-A-2001-330725.
The polymer used together with the discotic liquid crystalline molecule is preferably capable of changing the tilt angle of the discotic liquid crystalline molecule.
A cellulose ester can be mentioned as an example of a polymer. Preferable examples of the cellulose ester include those described in paragraph [0178] of JP-A No. 2000-155216. The addition amount of the polymer is preferably in the range of 0.1 to 10% by mass, and preferably in the range of 0.1 to 8% by mass with respect to the liquid crystal molecule so as not to disturb the alignment of the liquid crystal molecules. It is more preferable.
The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline molecules is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

(B-5) Formation of optically anisotropic layer The optically anisotropic layer is coated with a coating liquid containing liquid crystalline molecules and, if necessary, a polymerizable initiator and an optional component described later on the alignment film. Can be formed.
As a solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of organic solvents include amides (eg, N, N-dimethylformamide), sulfoxides (eg, dimethyl sulfoxide), heterocyclic compounds (eg, pyridine), hydrocarbons (eg, benzene, hexane), alkyl halides (eg, , Chloroform, dichloromethane, tetrachloroethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.

The coating liquid can be applied by a known method (eg, wire bar coating method, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method).
The thickness of the optically anisotropic layer is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm, and most preferably 1 to 10 μm.

(B-6) Fixing of alignment state of liquid crystalline molecules The aligned liquid crystalline molecules can be fixed while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. A photopolymerization reaction is preferred.
Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatic acyloin. Compound (described in US Pat. No. 2,722,512), polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of triarylimidazole dimer and p-aminophenyl ketone (US Pat. No. 3,549,367) Acridine and phenazine compounds (JP-A-60-105667, U.S. Pat. No. 4,239,850) and oxadiazole compounds (U.S. Pat. No. 4,212,970).
The amount of the photopolymerization initiator used is preferably in the range of 0.01 to 20% by mass, more preferably in the range of 0.5 to 5% by mass, based on the solid content of the coating solution.
It is preferable to use ultraviolet rays for light irradiation for polymerization of liquid crystalline molecules.
The irradiation energy is preferably in the range of ^{20mJ / cm 2 ~50J / cm 2} , more preferably in the range of 20~5000mJ / cm ^2, more preferably in the range of 100 to 800 mJ / cm ² . In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.
A protective layer may be provided on the optically anisotropic layer.

It is also preferable to combine this optical compensation film and a polarizing film (polarizing plate). Specifically, the optically anisotropic layer is formed by applying the coating liquid for the optically anisotropic layer as described above to the surface of the polarizing film. As a result, without using a polymer film between the polarizing film and the optically anisotropic layer, a thin polarizing plate having a small stress (strain × cross-sectional area × elastic modulus) associated with the dimensional change of the polarizing film is produced. . When the polarizing plate according to the present invention is attached to a large liquid crystal display device, an image with high display quality can be displayed without causing problems such as light leakage.
The inclination angle between the polarizing plate and the optical compensation layer should be extended so as to match the angle formed by the transmission axis of the two polarizing plates bonded to both sides of the liquid crystal cell constituting the LCD and the vertical or horizontal direction of the liquid crystal cell. Is preferred. A normal inclination angle is 45 °. Recently, however, devices that are not necessarily 45 ° have been developed for transmissive, reflective, and transflective LCDs, and it is preferable that the stretching direction can be arbitrarily adjusted in accordance with the design of the LCD.

(C) Application of an antireflection layer (antireflection film)
The antireflection film of the present invention has an antireflection film on a substrate, and is characterized by using the thermoplastic film of the present invention as a substrate.
The antireflection film generally includes a low refractive index layer which is also an antifouling layer, and at least one layer having a higher refractive index than that of the low refractive index layer (that is, a high refractive index layer and a medium refractive index layer). It is provided above.

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

(C-1) Layer configuration of coating type antireflection film An antireflection film comprising a layer configuration in the order of at least a medium refractive index layer, a high refractive index layer, and a low refractive index layer (outermost layer) on a substrate is as follows. Designed to have a refractive index that satisfies the relationship.
Refractive index of high refractive index layer> refractive index of medium refractive index layer> refractive index of transparent support> refractive index of low refractive index layer

Further, a hard coat layer may be provided between the transparent support and the medium refractive index layer. Furthermore, it may consist of a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer.
Examples thereof include JP-A-8-122504, JP-A-8-110401, JP-A-10-300902, JP-A-2002-243906, JP-A-2000-11706, and the like. Other functions may be imparted to each layer, for example, an antifouling low refractive index layer or an antistatic high refractive index layer (eg, JP-A-10-206603, JP-A-2002). -243906 publication etc.) etc. are mentioned.

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

(C-2) High Refractive Index Layer and Medium Refractive Index Layer The antireflective layer having a high refractive index is a curable film containing at least inorganic compound ultrafine particles having a high refractive index with an average particle size of 100 nm or less and a matrix binder. Consists of.
Examples of the high refractive index inorganic compound fine particles include inorganic compounds having a refractive index of 1.65 or more, preferably those having a refractive index of 1.9 or more. Examples thereof include oxides such as Ti, Zn, Sb, Sn, Zr, Ce, Ta, La, and In, and composite oxides containing these metal atoms.
In order to obtain such ultrafine particles, the surface of the particles is treated with a surface treatment agent (for example, silane coupling agents, etc .: JP-A-11-295503, JP-A-11-153703, JP-A-2000-9908). No., anionic compound or organometallic coupling agent: Japanese Patent Laid-Open No. 2001-310432, etc., core-shell structure with high refractive index particles as a core (: Japanese Patent Laid-Open No. 2001-166104, etc.), specific (For example, Japanese Patent Application Laid-Open No. 11-153703, Japanese Patent No. US6210858B1, Japanese Patent Application Laid-Open No. 2002-2776069, etc.).

Examples of the material forming the matrix include conventionally known thermoplastic resins and curable resin films.
Further, it is selected from a polyfunctional compound-containing composition containing at least two radically polymerizable and / or cationically polymerizable groups, an organometallic compound containing a hydrolyzable group, and a partial condensate composition thereof. At least one composition is preferred. Examples thereof include compounds described in JP-A Nos. 2000-47004, 2001-315242, 2001-31871, and 2001-296401.
A curable film obtained from a colloidal metal oxide obtained from a hydrolyzed condensate of metal alkoxide and a metal alkoxide composition is also preferred. For example, it describes in Unexamined-Japanese-Patent No. 2001-293818.

The refractive index of the high refractive index layer is generally 1.70 to 2.20. The thickness of the high refractive index layer is preferably 5 nm to 10 μm, and more preferably 10 nm to 1 μm.
The refractive index of the middle refractive index layer is adjusted to be a value between the refractive index of the low refractive index layer and the refractive index of the high refractive index layer. The refractive index of the middle refractive index layer is preferably 1.50 to 1.70.

(C-3) Low refractive index layer The low refractive index layer is formed by sequentially laminating on the high refractive index layer. The refractive index of the low refractive index layer is 1.20 to 1.55. Preferably it is 1.30-1.50.
It is preferable to construct as the outermost layer having scratch resistance and antifouling property. As means for greatly improving the scratch resistance, imparting slipperiness to the surface is effective, and conventionally known thin film layer means such as introduction of a silicone compound or introduction of fluorine by a fluorine-containing compound can be applied.

The refractive index of the fluorine-containing compound is preferably 1.35 to 1.50. More preferably, it is 1.36-1.47. The fluorine-containing compound is preferably a compound containing a crosslinkable or polymerizable functional group containing fluorine atoms in the range of 35 to 80% by mass.
For example, paragraph numbers [0018] to [0026] of Japanese Patent Application Laid-Open No. 9-222503, paragraph numbers [0019] to [0030] of Japanese Patent Application Laid-Open No. 11-38202, and paragraph numbers of Japanese Patent Application Laid-Open No. 2001-40284. [0027] to [0028], compounds described in JP-A No. 2000-284102, and the like.

The silicone compound is a compound having a polysiloxane structure, preferably containing a curable functional group or a polymerizable functional group in the polymer chain and having a crosslinked structure in the film. For example, reactive silicone (eg, Silaplane (manufactured by Chisso Corporation), silanol group-containing polysiloxane (Japanese Patent Laid-Open No. 11-258403, etc.) and the like can be mentioned.
The crosslinking or polymerization reaction of the fluorine-containing and / or siloxane polymer having a crosslinking or polymerizable group is carried out at the same time or after the coating composition for forming the outermost layer containing a polymerization initiator, a sensitizer, etc. It is preferable to carry out by light irradiation or heating.

Also preferred is a sol-gel cured film in which an organometallic compound such as a silane coupling agent and a specific fluorine-containing hydrocarbon group-containing silane coupling agent are cured by a condensation reaction in the presence of a catalyst.
For example, a polyfluoroalkyl group-containing silane compound or a partially hydrolyzed condensate thereof (Japanese Patent Laid-Open Nos. 58-142958, 58-147483, 58-147484, Japanese Patent Laid-Open Nos. 9-157582, 11) -106704), silyl compounds containing a poly "perfluoroalkyl ether" group which is a fluorine-containing long chain group (Japanese Patent Application Laid-Open Nos. 2000-117902, 2001-48590, 2002) 53804), and the like.

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

(C-4) Hard coat layer The hard coat layer is provided on the surface of the transparent support in order to impart physical strength to the antireflection film. In particular, it is preferably provided between the transparent support and the high refractive index layer.
The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of a light and / or heat curable compound. As the curable functional group, a photopolymerizable functional group is preferable, and the organometallic compound containing a hydrolyzable functional group is preferably an organic alkoxysilyl compound.
Specific examples of these compounds are the same as those exemplified for the high refractive index layer.
Specific examples of the constituent composition of the hard coat layer include those described in JP-A Nos. 2002-144913, 2000-9908, and WO 00/46617.
The high refractive index layer can also serve as a hard coat layer. In such a case, it is preferable to form fine particles dispersed in the hard coat layer using the method described for the high refractive index layer.

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

(C-5) Forward scattering layer The forward scattering layer is provided in order to give a viewing angle improvement effect when the viewing angle is inclined in the vertical and horizontal directions when applied to a liquid crystal display device. By dispersing fine particles having different refractive indexes in the hard coat layer, it can also serve as a hard coat function.
For example, Japanese Patent Application Laid-Open No. 11-38208 specifying a forward scattering coefficient, Japanese Patent Application Laid-Open No. 2000-199809 having a relative refractive index of a transparent resin and fine particles in a specific range, and Japanese Patent Application Laid-Open No. 2002 specifying a haze value of 40% or more. -107512 gazette etc. are mentioned.

(C-6) Other layers In addition to the above layers, a primer layer, an antistatic layer, an undercoat layer, a protective layer, and the like may be provided.

(C-7) Coating method Each layer of the antireflection film is formed by a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating, a micro gravure method or an extrusion coating method (US patent). No. 2,681,294) can be formed by coating.

(C-8) Anti-glare function The antireflection film may have an anti-glare function that scatters external light. The antiglare function is obtained by forming irregularities on the surface of the antireflection film. When the antireflection film has an antiglare function, the haze of the antireflection film is preferably 3 to 30%, more preferably 5 to 20%, and most preferably 7 to 20%.

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

(D) Liquid crystal display device The liquid crystal display device of the present invention can use a polarizing plate, an optical compensation sheet, an antireflection film or the like using the thermoplastic film of the present invention as described above, instead of a known one. . Each liquid crystal mode of the liquid crystal display layer of the present invention will be described.

(TN mode liquid crystal display)
The TN mode liquid crystal display device is most frequently used as a color TFT liquid crystal display device, and is described in many documents. The alignment state in the liquid crystal cell in the TN mode black display is an alignment state in which the rod-like liquid crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie in the vicinity of the cell substrate.

(OCB mode liquid crystal display)
The OCB mode liquid crystal display device is a bend alignment mode liquid crystal cell in which rod-like liquid crystal molecules are aligned (symmetrically) in substantially opposite directions at the upper and lower portions of the liquid crystal cell. Liquid crystal display devices using a bend alignment mode liquid crystal cell are disclosed in US Pat. Nos. 4,583,825 and 5,410,422. Since the rod-like liquid crystal molecules are symmetrically aligned at the upper and lower portions of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. Therefore, this liquid crystal mode is also called an OCB (Optically Compensatory Bend) liquid crystal mode.
Similarly to the TN mode, the liquid crystal cell in the OCB mode is in a black display, and the alignment state in the liquid crystal cell is such that the rod-like liquid crystal molecules rise in the center of the cell and the rod-like liquid crystal molecules lie in the vicinity of the cell substrate. .

(VA mode liquid crystal display device)
The VA mode liquid crystal display device is characterized in that the rod-like liquid crystalline molecules are aligned substantially vertically when no voltage is applied. (1) No voltage is applied to the VA mode liquid crystal cell. In addition to a narrowly-defined VA mode liquid crystal cell (described in JP-A-2-176625), which is sometimes aligned substantially vertically and aligned substantially horizontally when a voltage is applied, Liquid crystal cell with multi-domain mode (MVA mode) (SID97, Digest of tech. Papers (preliminary report) 28 (1997) 845), (3) The rod-like liquid crystal molecules are substantially vertically aligned when no voltage is applied. Mode (n-ASM mode) liquid crystal cell (described in Proceedings 58-59 (1998) of the Japanese Liquid Crystal Society) and (4) SURVAIVAL mode Liquid crystal cells (announced at LCD International 98).

(IPS mode liquid crystal display)
The IPS mode liquid crystal display device is characterized in that rod-like liquid crystalline molecules are substantially aligned horizontally in a plane when no voltage is applied, and this is switched by changing the alignment direction of the liquid crystal with or without voltage application. Is the feature. Specifically, JP 2004-365951 A, JP 2004-12731 A, JP 2004-215620 A, JP 2002-221726 A, JP 2002-55341 A, JP 2003-195333 A. Those described in the publication can be used.

(Other liquid crystal display devices)
The ECB mode and the STN mode can be optically compensated in the same way as described above.

It should be noted that the present invention and the techniques disclosed in the following patent publications can be used in combination without departing from the spirit of the present invention.
Japanese Utility Model Laid-Open No. 3-110418, Japanese Patent Application Laid-Open No. 5-119216, Japanese Patent Application Laid-Open No. 5-162261, Japanese Patent Application Laid-Open No. 5-182518, Japanese Patent Application Laid-Open No. 5-19115, Japanese Patent Application Laid-Open No. JP-A-5-264811, JP-A-5-281411, JP-A-5-281417, JP-A-5-281537, JP-A-5-288921, JP-A-5-288923, JP-A-5-281923. No. 3111119, JP-A-5-339395, JP-A-5-40204, JP-A-5-45512, JP-A-6-109922, JP-A-6-123805, JP-A-6-160626. JP-A-6-214107, JP-A-6-214108, JP-A-6-214109, JP-A-6-2 No. 2209, JP-A-6-222353, JP-A-6-234175, JP-A-6-235810, JP-A-6-258520, JP-A-6-264030, JP-A-6-305270 JP-A-6-331826, JP-A-6-347641, JP-A-6-75110, JP-A-6-75111, JP-A-6-82279, JP-A-6-93133, JP-A-7-104126, JP-A-7-134212, JP-A-7-181322, JP-A-7-188383, JP-A-7-230086, JP-A-7-290652, JP-A-7-290652. 7-294903, JP-A-7-294904, JP-A-7-294905, JP-A-7-325219 JP-A-7-56014, JP-A-7-56017, JP-A-7-92321, JP-A-8-122525, JP-A-8-146220, JP-A-8-171016, JP-A-8-188661, JP-A-8-21999, JP-A-8-240712, JP-A-8-25575, JP-A-8-286179, JP-A-8-292322, JP-A-8. No. -297211, JP-A-8-304624, JP-A-8-313881, JP-A-8-43812, JP-A-8-62419, JP-A-8-62422, JP-A-8-76112. JP, 8-94834, JP-A-9-137143, JP-A-9-197127, JP-A-9-251110. JP-A-9-258023, JP-A-9-269413, JP-A-9-269414, JP-A-9-281383, JP-A-9-288212, JP-A-9-288213, JP-A-9-292525, JP-A-9-292526, JP-A-9-294959, JP-A-9-318817, JP-A-9-80233, JP-A-10-10320, JP-A-10-32020 10-104428, JP-A-10-111403, JP-A-10-11507, JP-A-10-123302, JP-A-10-123322, JP-A-10-123323, JP-A-10- No. 176118, JP-A-10-186133, JP-A-10-264322, JP-A-10-2 No. 8133, JP-A-10-268134, JP-A-10-319408, JP-A-10-332933, JP-A-10-39137, JP-A-10-39140, JP-A-10-68821 JP-A-10-68824, JP-A-10-90517, JP-A-11-116903, JP-A-11-181131, JP-A-11-211901, JP-A-11-2111914, JP-A-11-242119, JP-A-11-246663, JP-A-11-246694, JP-A-11-256117, JP-A-11-258425, JP-A-11-263861, JP-A-11-26361 11-287902, JP-A-11-295525, JP-A-11-295 No. 27, JP-A-11-302423, JP-A-11-309830, JP-A-11-323552, JP-A-11-335641, JP-A-11-344700, JP-A-11-349947. JP-A-11-95011, JP-A-11-95030, JP-A-11-95208, JP-A-2000-109780, JP-A-2000-11070, JP-A-2000-119657, JP 2000-141556, JP 2000-147208, JP 2000-17099, JP 2000-171603, JP 2000-171618, JP 2000-180615, JP 2000-187102, JP-A 2000-187106, JP 2000-191819, JP 2000-191821, JP 2000-193804, JP 2000-204189, JP 2000-206306, JP 2000-214323, JP 2000-214329, 2000-230159, 2000-235107, 2000-241626, 2000-250038, 2000-267095, 2000- No. 284122, JP-A 2000-304927, JP-A 2000-304929, JP-A 2000-304929, JP-A 2000-309195, JP-A 2000-309196, JP-A 2000-309198 JP, 2000-309, Gazette 42, JP 2000-310704, 2000-310708, 2000-310709, 2000-310710, 2000-310711, 2000-310712 JP, 2000-310713, 2000-310714, 2000-310715, 2000-310716, 2000-310717, 2000-321560, JP 2000-321567, JP 2000-338309, JP 2000-338329, JP 2000-344905, JP 2000-347016, JP 2000-347017, JP JP 2000-347026, JP 2 Nos. 00-347027, 2000-347029, 2000-347030, 2000-347031, 2000-347032, 2000-347033, 2000- JP 347034, JP 2000-347035, JP 2000-347037, JP 2000-347038, JP 2000-86989, JP 2000-98392, JP 2001-100012. Gazette, JP-A-2001-108805, JP-A-2001-108806, JP-A-2001-133627, JP-A-2001-133628, JP-A-2001-142062, JP-A-2001-142072, JP 2001-174630 A JP-A-2001-174634, JP-A-2001-174737, JP-A-2001-179902, JP-A-2001-183526, JP-A-2001-188103, JP-A-2001-188124, JP 2001-188125 A, JP 2001-188225 A, JP 2001-188231 A, JP 2001-194505 A, JP 2001-228511 A, JP 2001-228333 A, JP 2001 A. -242461, JP-A-2001-242546, JP-A-2001-247834, JP-A-2001-26061, JP-A-2001-264517, JP-A-2001-272535, JP-A-2001-278924 Publication, JP 2001-279A JP, JP 2001-287308, JP 2001-305345, JP 2001-311827, JP 2001-350005, JP 2001-356207, JP 2001-356213. JP-A-2001-42122, JP-A-2001-42323, JP-A-2001-42325, JP-A-2001-4819, JP-A-2001-4829, JP-A-2001-4830, JP-A-2001-4831, JP-A-2001-4832, JP-A-2001-4834, JP-A-2001-4835, JP-A-2001-4836, JP-A-2001-4838, JP-A-2001. JP-A-4839, JP-A-2001-51118, JP-A-2001-51119. JP, 2001-51120, JP 2001-51273, JP 2001-51274, JP 2001-55573, JP 2001-66431, JP 2001-66597, JP 2001-74920 A, JP 2001-81469 A, JP 2001-83329 A, JP 2001-83515 A, JP 2002-162628 A, JP 2002-169024 A, JP JP-A 2002-189421, JP-A 2002-2013367, JP-A 2002-20410, JP-A 2002-258046, JP-A 2002-275391, JP-A 2002-294174, JP-A 2002-2002 No. 311214, JP-A No. 2002-311246, JP 2002-328233, JP 2002-338703, JP 2002-363266, JP 2002-365164, JP 2002-370303, JP 2002-40209, JP 2002 -48917, JP 2002-6109, JP 2002-71950, JP 2003-105540, JP 2003-114331, JP 2003-131036, JP 2003-139952. JP, JP 2003-172819, JP 2003-35819, JP 2003-43252, JP 2003-50318, JP 2003-96066, JP 2006-45501. JP, 2006-45502, JP, 200 -45499, JP-A 2006-45500, JP-A 2006-182008, JP-A 2006-241433, JP-A 2006-348123, JP-A 2005-325258, JP-A 2006-2026, JP 2006-2025, JP 2006-183005, JP 2006-183004, JP 2006-143873, JP 2006-257204, JP 2006-205472, JP 2006-241428 JP, JP-A-2006-251746, JP-A-2007-1198, JP-A-2007-1238, International Publication WO2005 / 103122, JP-A-2006-176636, JP-A-2006-243688. , JP 2006-327105 A JP, 2006-124642, JP 2006-205708, JP 2006-341443, JP 2006-199913, JP 2006-335050, JP 2007-8154, JP, 2006-334840, JP, 2006-341450, JP, 2006-327162, JP, 2006-341510, JP, 2006-327161, JP, 2006-327107, JP JP-A 2006-327160, JP-A 2006-328316, JP-A 2006-334839, JP-A 2007-8151, JP-A 2007-1286, JP-A 2006-327106, JP-A 2006-2006. Japanese Patent No. 334841, Japanese Patent Laid-Open No. 2006-334842 Publication, JP 2005-330411 A, JP 2006-116945 A, JP 2005-301225 A, JP 2007-1287 A, JP 2006-348268 A, International Publication WO 2006/132367 Pamphlet. ,
JP, 2005-178194, JP, 2006-336004, JP, 2006-249418, JP, 2007-2216, JP, 2006-28345, JP, 2006-215535, JP JP 2006-28387 A, JP 2007-2215 A, JP 2006-343479 A, JP 2006-2631992 A, JP 2000-352620 A, JP 2005-088578 A, JP 2005-2005 A. No. 300888, JP-A 2005-342929, JP-A 2006-021459, JP-A 2006-030425, JP-A 2006-036840, JP-A 2006-045306, JP-A 2006-045307 Publication, JP 2006-058825 A JP 2006-063169, JP 200677067, JP 2006-77113, JP 2006-82261, JP 2006-91035, JP 2006-91078, JP JP-A-2006-104374, JP-A-2006-106247, JP-A-2006-117117, JP-A-2006-1111797, JP-A-2006-113175, JP-A-2006-113551, JP-A-2006- No. 113567, JP-A 2006-116904, JP-A 2006-117714, JP-A 2006-119182, JP-A 2006-119183, JP-A 2006-123513, JP-A 2006-123177 Japanese Patent Laid-Open No. 2006-124629 JP, 2006-137721, JP 2006-142800, JP 2006-163033, JP 2006-163034, JP 2006-171404, JP 2006-178020, JP, 2006-182020, JP, 2006-182865, JP, 2006-188663, JP, 2006-195407, JP, 2006-208934, JP, 2006-219615, JP JP-A-2006-220814, JP-A-2006-224589, JP-A-2006-249221, JP-A-2006-256082, JP-A-2006-272616, JP-A-2006-290929, JP-A-2006- No. 293201, JP 2006-3 No. 01500, Japanese Patent Application Laid-Open No. 2006-301592.

  The measurement method used in the present invention is described below.

(1) Re, Rth
First, each retardation in the present invention will be described. In this specification, Re and Rth (unit: nm) are determined according to the following method. First, the film was conditioned at 25 ° C. and 60% relative humidity for 24 hours, and then a prism coupler (MODEL2010 Prism Coupler: manufactured by Metricon) was used. At 25 ° C. and 60% relative humidity, the following formula was used: An average refractive index (n) represented by (a) is obtained.
Formula (a): n = (n _TE × 2 + n _TM ) / 3
[ _Where n _TE is a refractive index measured with polarized light in the film plane direction, and n _TM is a refractive index measured with polarized light in the film surface normal direction. ]

In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at a wavelength λ, respectively. Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments).
When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method.

Rth (λ) is Re (λ), with the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotation axis) (in the absence of the slow axis, any in-plane value) Measurements were made at 11 points in total by making light of wavelength λ nm incident from each inclined direction in steps of 10 ° from −50 ° to + 50 ° from the normal direction to the normal direction of the film). Then, KOBRA 21ADH or WR is calculated based on the measured retardation value, average refractive index, and input film thickness value.
In the above, there is no particular description regarding λ, and when only Re and Rth are described, it represents a value measured using light with a wavelength of 590 nm. In addition, in the case of a film having a retardation value of zero at a certain tilt angle with the in-plane slow axis from the normal direction as the rotation axis, the retardation value at a tilt angle larger than that tilt angle. After changing its sign to negative, KOBRA 21ADH or WR calculates.

  In addition, the retardation value is measured from the two inclined directions, with the slow axis as the tilt axis (rotation axis) (when there is no slow axis, the arbitrary direction in the film plane is the rotation axis), Based on the value, the average refractive index, and the input film thickness value, Rth can also be calculated from the following formulas (b) and (c).

［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−デーション値をあらわす。また、ｎｘは面内における遅相軸方向の屈折率を表し、ｎｙは面内においてｎｘに直交する方向の屈折率を表し、ｎｚはｎｘおよびｎｙに直交する方向の屈折率を表す。］

[In the formula, Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. Further, nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction perpendicular to nx in the plane, and nz represents the refractive index in the direction perpendicular to nx and ny. ]

Formula (c): Rth = ((nx + ny) / 2−nz) × d

When the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film having no so-called optical axis, Rth (λ) is calculated by the following method.
Rth (λ) is Re (λ), and the in-plane slow axis (determined by KOBRA 21ADH or WR) is the tilt axis (rotation axis) from −50 ° to + 50 ° with respect to the film normal direction. Measured at 11 points by injecting light of wavelength λ nm from each inclined direction in 10 ° steps, and KOBRA 21ADH or WR is calculated based on the measured retardation value, average refractive index, and input film thickness value. To do.
By inputting these average refractive index and film thickness, KOBRA 21ADH or WR calculates nx, ny, and nz. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

(2) Temperature dependence of Re and Rth (ΔRe temp, ΔRth temp)
The sample film was conditioned for 24 hours in an atmosphere of 25 ° C. and a relative humidity of 60%, and the in-plane retardation value and the retardation value in the thickness direction were measured to be Re and Rth, respectively. Then put it in a 60 ° C. air thermostat without applying tension, leave it for 1 hour, take it out, measure the in-plane retardation value and the retardation value in the thickness direction by the method described above after 3 minutes, It z Re60 ° C and Rth60 ° C.
Differences Re and Rth between 25 ° C. and 60 ° C. ΔRe temp and ΔRth temp were defined by the following equations, respectively.
ΔRe temp = | Re-Re60 ° C. |
ΔRth temp = | Rth−Rth60 ° C. |

(3) Temperature dependent distribution unevenness of Re and Rth (ΔRe film, ΔRth film)
As shown in FIG. 1, a sample having a size of 2 cm × 2 cm is sampled at intervals of 5 cm along the width direction (TD) at the time of film formation, and at intervals of 5 cm along the film formation direction (MD). To do. Each sample is subjected to the Re and Rth temperature dependency measurement tests described in (2) above, and ΔRe temp and ΔRth temp are measured.

ΔRe temp in each sample, ΔRth temp maximum value, minimum value to ΔRe film,
ΔRth film was defined by the following equation.
ΔRe film = maximum ΔRe temp−minimum ΔRe temp
ΔRth film = maximum ΔRth temp−minimum ΔRth temp

(4) Degree of substitution of cellulose acylate resin The degree of acyl substitution of cellulose acylate resin is determined according to Carbohydr. Res. 273 (1995) 83-91 may be determined by ¹³ C-NMR according to the method described in (Tezuka et al.).

(5) Residual solvent amount A sample film of 300 mg dissolved in 30 ml of methyl acetate (sample A) and a sample film dissolved in 30 ml of dichloromethane (sample B) are prepared. Subsequently, these are measured under the following conditions using gas chromatography (GC).
Column: DB-WAX (0.25 mmφ × 30 m, film thickness 0.25 μm)
Column temperature: 50 ° C
Carrier gas: Nitrogen Analysis time: 15 minutes Sample injection volume: 1 μml

The amount of solvent can be determined by the following method.
For each peak of sample A other than the solvent (methyl acetate), the content is determined using a calibration curve, and the sum is defined as Sa. In sample B, the content rate is determined using a calibration curve for each peak in the region hidden by the solvent peak in sample A, the sum is Sb, and the sum of Sa and Sb is the residual solvent amount.

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

<Example 1>
(1) Cellulose acylate resin (i) Synthesis of cellulose acetate propionate (CAP) 150 parts by mass of cellulose (hardwood pulp) and 75 parts by mass of acetic acid are placed in a reaction vessel equipped with a reflux apparatus and heated to 60 ° C. While stirring vigorously. Samples were prepared by changing the number of foreign matters derived from unreacted cellulose by changing the pretreatment time. The cellulose subjected to such pretreatment swelled and crushed to form a fluff shape. The reaction vessel was placed in an ice water bath at 2 ° C. for 30 minutes and cooled.

Separately, as an acylating agent, a mixture of 1410 parts by mass of propionic anhydride and 10.5 parts by mass of sulfuric acid was prepared, cooled to −30 ° C., and then put into a reaction vessel containing the pretreated cellulose at once. added. After 30 minutes, the external temperature was gradually increased, and the internal temperature was adjusted to 25 ° C. after 2 hours from the addition of the acylating agent. The reaction vessel was cooled in an ice water bath at 5 ° C., the internal temperature was adjusted to 10 ° C. 0.5 hours after addition of the acylating agent, and the internal temperature was 23 ° C. after 2 hours, and the internal temperature was 23 ° C. The mixture was further stirred for 3 hours. The reaction vessel was cooled in an ice water bath at 5 ° C., and 120 parts by mass of 25% by mass hydrous acetic acid cooled to 5 ° C. was added over 1 hour. The internal temperature was raised to 40 ° C. and stirred for 2 hours (aging). Next, a solution obtained by dissolving magnesium acetate tetrahydrate in 2-fold mol of sulfuric acid in 50% by mass aqueous acetic acid was added to the reaction vessel, and the mixture was stirred for 30 minutes. 25 parts by mass of hydrous acetic acid 1000 parts by mass, 33% by mass hydrous acetic acid 500 parts by mass, 50% by mass hydrous acetic acid 1000 parts by mass and water 1000 parts by mass were added in this order to precipitate cellulose acetate propionate. The obtained cellulose acetate propionate precipitate was washed with warm water. After washing, the mixture was stirred in a 0.005 mass% calcium hydroxide aqueous solution at 20 ° C. for 0.5 hour, further washed with water until the pH of the washing solution became 7, and then vacuum dried at 70 ° C.

  According to NMR and GPC measurements, the obtained cellulose acetate propionate had an acetyl (Ac) degree of 0.45, a propionyl (Pr) degree of 2.45, and a degree of polymerization of 160. The composition was measured by the NMR method described above, and the degree of polymerization was measured using GPC as follows.

-Number average molecular weight (Mn) was determined using THF as an eluent and monodisperse polystyrene as a standard molecular weight.
The molecular weight (m) per segment was determined from the composition determined by NMR.
Mn was divided by m to determine the degree of polymerization (number average degree of polymerization: DPn).

(Ii) Synthesis of Cellulose Acetate Butyrate (CAB) 100 parts by mass of cellulose (cotton linter) and 135 parts by mass of acetic acid were placed in a reaction vessel equipped with a reflux apparatus and stirred vigorously while heating to 60 ° C. Samples were prepared by changing the number of foreign matters derived from unreacted cellulose by changing the pretreatment time. The cellulose subjected to such pretreatment swelled and crushed to form a fluff shape. The reaction vessel was placed in an ice water bath at 5 ° C. for 60 minutes and cooled.

  Separately, a mixture of 1080 parts by weight of butyric anhydride and 10.0 parts by weight of sulfuric acid was prepared as an acylating agent, cooled to −20 ° C., and then added to a reaction vessel containing pretreated cellulose at once. After 30 minutes, the external temperature was raised to 20 ° C. and reacted for 5 hours. The reaction vessel was cooled in an ice water bath at 5 ° C., and 2400 parts by mass of 12.5 mass% hydrous acetic acid cooled to about 5 ° C. was added over 1 hour. The internal temperature was raised to 30 ° C. and stirred for 1.5 hours (aging). Subsequently, 100 mass parts of 50 mass% aqueous solution of magnesium acetate tetrahydrate was added to the reaction container, and it stirred for 30 minutes. 1000 parts by mass of acetic acid and 2500 parts by mass of 50% by mass hydrous acetic acid were gradually added to precipitate cellulose acetate butyrate. The obtained cellulose acetate butyrate precipitate was washed with warm water. After washing, the mixture was stirred in a 0.005 mass% calcium hydroxide aqueous solution for 0.5 hour, further washed with water until the pH of the washing solution became 7, and then dried at 70 ° C.

  The obtained cellulose acetate butyrate had an acetyl (Ac) degree of 0.84, a butyryl (Bu) degree of 2.12, and a degree of polymerization of 180.

(Iii) Synthesis of other cellulose acylate resins By changing the type and amount of acylating agent, the degree of substitution is changed, and the degree of polymerization is changed by changing the aging time. An acylate resin was synthesized.
In addition, cellulose acylate esterified with benzoic acid and acetic acid was synthesized as cellulose acylate having a substituted or unsubstituted aromatic acyl group bonded thereto in accordance with Example 1 of JP-A No. 2002-3201. However, as the raw material cellulose acylate, 2.0-substituted and 2.45-substituted cellulose acetates were used, respectively. As a result, an aromatic acyl group-substituted cellulose acylate having an acetic acid substitution degree = 2.0 and a benzoic acid substitution degree = 1.0, and an acetic acid substitution degree = 2.45 and an benzoic acid substitution degree = 0.55 aromatic Acyl group-substituted cellulose acylate was obtained.
In addition to this, cellulose acylate having an aromatic acyl group bonded thereto in Examples 2 to 7 of JP-A No. 2002-3201 was synthesized, formed into a film in the same manner as Examples 35 and 36 in Table 1, and stretched in Table 2 Although it extended | stretched like the films 11-15, all obtained the favorable result similarly to the said cellulose acylate substituted with the benzoic acid.
Further, cellulose acetate propionate having an acetyl substitution degree of 1.8, a propionyl substitution degree of 0.8, and a number average polymerization degree of 230 was synthesized according to the above-described method, and described in the examples of JP-A-2006-195407. A plasticizer of Example 39 was added.

(2) Melt film formation (i) Pelletization of cellulose acylate resin 100 parts by mass of the cellulose acylate, 0.3 parts by mass of stabilizer (Sumitomo Chemical Co., Ltd., Sumilizer GP), silicon dioxide particles (Aerosil R972V) ) 0.05 part by weight, UV absorber (2- (2′-hydroxy-3 ′, 5-di-tert-butylphenyl) -benzotriazole 0.05 part by weight, 2,4-hydroxy-4-methoxy-benzophenone 0.1 parts by mass) was mixed.
These were dried at 100 ° C. for 3 hours to reduce the water content to 0.1% by mass or less, melted at 180 ° C. using a twin-screw kneader, then extruded into warm water at 60 ° C., and then cut into diameters. It was molded into a cylindrical pellet 3 mm long and 5 mm long. The residual solvent amount was 0.01% by mass or less.

(Ii) Melt Film Formation The cellulose acylate pellets prepared by the above method were dried at 100 ° C. for 5 hours using dehumidified air having a dew point temperature of −40 ° C. to make the water content 0.01% by mass or less. This was put into a hopper at 80 ° C. and melted with a melt extruder adjusted from 180 ° C. (inlet temperature) to 230 ° C. (outlet temperature). In addition, the diameter of the screw used for this was 60 mm, L / D = 50, and the compression ratio was 4. The resin extruded from the melt extruder is weighed and sent out by a gear pump. At this time, the number of revolutions of the extruder is changed so that the resin pressure before the gear pump can be controlled at a constant pressure of 10 MPa. The melt resin delivered from the gear pump was filtered through a leaf disk filter having a filtration accuracy of 5 μm, and extruded from a hanger coat die with a slit interval of 0.8 mm via a static mixer. The extruded resin was heat-treated during the film forming process by the method shown in Table 1 to obtain a thermoplastic film. When the touch roll was used, the unstretched film was brought into contact with the touch roll under the conditions described in Table 1 on the most upstream cast roll. The touch roll was the one described in Example 1 of JP-A-11-235747 (the one described as a double holding roll), and the temperature was adjusted to (Tg-5 ° C.) (however, a thin metal outer cylinder) The thickness was 3 mm).

  The solidified melt resin is peeled off from the casting drum, both ends (5% each of the total width) are trimmed immediately before winding, and then both ends are subjected to a thicknessing process (knurling) of 10 mm width and 50 μm height, and then 30 m / An unstretched film having a width of 1.5 m and a length of 3000 m was obtained. When the residual solvent amount of these films was measured, the residual solvent was not measured.

Moreover, Tg of resin was measured by the following method using DSC.
(Tg measurement) 20 mg of a sample was put in a DSC measurement pan, heated from 30 ° C. to 250 ° C. at 10 ° C./min in a nitrogen stream, and then cooled to 30 ° C. at −10 ° C./min. After that, when the temperature was raised again from 30 ° C. to 250 ° C., the temperature at which the baseline started to deviate from the low temperature side was defined as the glass transition temperature (Tg).

(Evaluation)
About the obtained film, the temperature dependence (ΔRe temp, ΔRth temp) of Re, Rth, Re, Rth, and the temperature dependence distribution unevenness (ΔRe film, ΔRth film) of Re, Rth were measured according to the above-described methods. The results are shown in Table 1 below.
At this time, good performance was obtained with the embodiment of the present invention.

(3) Preparation of polarizing plate (3-1) Surface treatment The cellulose acylate film was saponified by the following dipping method. Although the following coating saponification was also performed, the same results as in the immersion saponification were obtained.
(I) Immersion saponification Using a 1.5 mol / L NaOH aqueous solution adjusted to 60 ° C. as a saponification solution, a cellulose acylate film was immersed in this for 2 minutes. Then, after being immersed in 0.05 mol / L sulfuric acid aqueous solution for 30 seconds, it was passed through a water-washing bath.

(Ii) Coating saponification 20 parts by mass of water was added to 80 parts by mass of isopropanol, and KOH was further dissolved so as to have a concentration of 1.5 mol / L. This was coated on a cellulose acylate film at 60 ° C. at 10 g / m ² and saponified for 1 minute. After this, 5
Washing was performed by spraying warm water at 0 ° C. for 1 minute at 10 L / m ² · min using a spray.

(3-2) Production of Polarizing Film According to Example 1 of Japanese Patent Application Laid-Open No. 2001-141926, a circumferential speed difference was given between two pairs of nip rolls, and a polarizing film having a thickness of 20 μm was formed by stretching in the longitudinal direction.

(3-3) Bonding Using the cellulose acylate film obtained by forming, stretching, and saponifying the polarizing film thus obtained, PVA (manufactured by Kuraray Co., Ltd., PVA) was formed. -117H) A 3% aqueous solution was bonded as an adhesive to prepare a polarizing plate. The Fujitac (Fuji Photo Film TD80) described below was also saponified by the above method.
Polarizing plate A: present invention cellulose acylate / polarizing film / Fujitac

(3-4) Evaluation 20-inch VA type liquid crystal described in FIGS. 2 to 9 of Japanese Patent Application Laid-Open No. 2000-154261 with the polarizing plate obtained in this way, with the stretched cellulose acylate resin on the liquid crystal side. The display device was attached to a liquid crystal display device. This was displayed as white on the entire surface at a high temperature (60 ° C.), and a region of unevenness (light leakage) was visually measured to obtain a ratio to the total area of the display portion.

表１中、熱処理方法の「Ａ」はキャスティングドラムを熱処理温度に設定したものであり、「Ｂ」は内部を熱処理温度雰囲気に設定した恒温槽を用いたものであり、「Ｃ」はフィルム両面からＩＲヒータを用いてフィルム表面を熱処理温度に加温したものである。

In Table 1, “A” of the heat treatment method is that in which the casting drum is set at the heat treatment temperature, “B” is that using a thermostatic bath in which the inside is set in the heat treatment temperature atmosphere, and “C” is on both sides of the film. The film surface is heated to a heat treatment temperature using an IR heater.

As can be seen from Table 1, the performance of the present invention was obtained.
On the other hand, in the sample (Comparative Example 1) in which the temperature of the heat treatment process is out of the range of the present invention, residual strain is present in the cellulose acylate film, and therefore, temperature irregularities in both Re and Rth are more frequently generated. It can be seen that a lot of color unevenness occurred in the device. In Comparative Example 2, the resin was melted due to the high temperature, and the performance evaluation was not possible.

  Further, the sample (Comparative Example 3) having a transport tension smaller than that of the present invention could not transport the film. On the other hand, in the sample (Comparative Example 4) having a conveyance tension larger than that of the present invention, retardation and film residual distortion occurred during conveyance, and color unevenness of the liquid crystal display device occurred.

  In the sample (Comparative Example 5) in which the heat treatment time is shorter than that of the present invention, the cellulose acylate film has a residual strain because the heat treatment cannot be sufficiently performed, and more temperature irregularities of both Re and Rth occur. It can be seen that many color irregularities occurred. Even in the samples longer than the present invention, retardation and residual strain were generated.

  In addition, compared with the sample of Example 1 described in Japanese Patent Application Laid-Open No. 2006-63169 (Comparative Example 7 in Table 1), the present invention significantly reduces both Re and Rth temperature variations and Re and Rth temperature dependency distribution variations. Can improve. On the other hand, what carried out the present invention under conditions closest to this (Example 34 in Table 1) obtained good performance.

(8) Production / Evaluation of Stretched Film The unstretched sheet of Example 6 and the unstretched sheets of Examples 35 to 39 in Table 1 are the following magnifications at 3000% / min at a glass transition temperature (Tg + 10) ° C. of each film. The film was stretched (same conditions for longitudinal stretching and lateral stretching) to obtain a film having the following performance. The draw ratio here is defined by the following formula.
Stretch ratio (%) = 100 × {(Length after stretching) − (Length before stretching)} / (Length before stretching)

  The temperature dependence (ΔRe temp, ΔRth temp) of retardation of these stretched films and the temperature dependence unevenness of retardation (ΔRe film, ΔRth film) are both 10% using the film-forming film of the present invention. The following shows good performance.

The stretched cellulose acylate film thus obtained was saponified by the above-described method, and then a polarizing plate having the following composition was prepared as described above.
Polarizing plate C: Stretched cellulose acylate / polarizing layer / Fujitack Polarizing plate D: Stretched cellulose acylate / polarizing layer / cellulose acylate

The obtained polarizing plate was attached in place of the polarizing plate of the 20-inch VA liquid crystal display device liquid crystal display device described in FIGS. 2 to 9 of JP-A No. 2000-154261. After lapse of 500 hours at 35 ° C., the entire surface was displayed as white, and a region where rainbow-like unevenness (color change) was visually observed from an angle of 45 °, and the ratio to the total area of the display portion was measured. In all cases, the color change of the liquid crystal display panel was 10% or less, and good performance was shown. Good performance was obtained with the present invention.
Similar results were obtained with films obtained by stretching the unstretched films of the present invention 2-33 shown in Table 1.

<Example 2>
(1) Saturated norbornene resin (i) Production of saturated norbornene resin A 6-methyl-1,4,5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene As a polymerization catalyst, 10 parts by mass of a 15% cyclohexane solution of triethylaluminum, 5 parts by mass of triethylamine, and 10 parts by mass of a 20% cyclohexane solution of titanium tetrachloride were added, and ring-opening polymerization was performed in cyclohexane. The polymer was hydrogenated with a nickel catalyst to obtain a polymer solution. This polymer solution was coagulated in isopropyl alcohol and dried to obtain a powdery resin. The number average molecular weight of this resin was 40,000, the hydrogenation rate was 99.8% or more, and the Tg was 139 ° C.

(Ii) producing a saturated norbornene resin B 8- methyl-8-methoxycarbonyltetracyclo [4.4.0.12 ^5,17. 10] -3-dodecene (specific monomer B) 100 parts by mass and 5- (4-biphenylcarbonyloxy) bicyclo [2.2.1] hept-2-ene (specific monomer A) 150 parts by mass Then, 18 parts by mass of 1-hexene (molecular weight regulator) and 750 parts by mass of toluene were charged into a reaction vessel substituted with nitrogen, and this solution was heated to 60 ° C. Next, 0.62 parts by mass of a toluene solution of triethylaluminum (1.5 mol / l) as a polymerization catalyst and tungsten hexachloride modified with tert-butanol and methanol (tert-butanol: methanol: tungsten) are added to the solution in the reaction vessel. = 3.75 mol: 0.3 mol: 1 mol) of a toluene solution (concentration 0.05 mol / L) is added in an amount of 3.7 parts by mass, and this system is heated and stirred at 80 ° C. for 3 hours to cause a ring-opening polymerization reaction. Thus, a ring-opening polymer solution was obtained. The polymerization conversion rate in this polymerization reaction was 97%, and the intrinsic ring viscosity (ηinh) of the obtained ring-opened polymer measured in chloroform at 30 ° C. was 0.65 dl / g.
The autoclave was charged with 4,000 parts by mass of the ring-opening polymer solution thus obtained, and 0.48 part by mass of RuHCl (CO) [P (C ₆ H ₅ ) ₃ ] ₃ was added to the ring-opening polymer solution. And a hydrogenation reaction was performed by heating and stirring for 3 hours under the conditions of a hydrogen gas pressure of 100 kg / cm ² and a reaction temperature of 165 ° C. After cooling the obtained reaction solution (hydrogenated polymer solution), the hydrogen gas was released. This reaction solution was poured into a large amount of methanol to separate and recover a coagulated product, which was dried to obtain a hydrogenated polymer (specific cyclic polyolefin resin). The hydrogenated polymer thus obtained was measured for hydrogenation rate of olefinically unsaturated bonds using 400 MHz, ¹ H-NMR, and found to be 99.9%. When the number average molecular weight (Mn) and weight average molecular weight (Mw) in terms of polystyrene were measured by the GPC method (solvent: tetrahydrofuran), the number average molecular weight (Mn) was 39,000 and the weight average molecular weight (Mw) was 126,000. The molecular weight distribution (Mw / Mn) was 3.23. Moreover, Tg was 110 degreeC.

(Iii) Saturated norbornene resin C
The saturated norbornene compound (Tg: 127 ° C.) described in Example 2 of JP-A-2005-330465 was used as the saturated norbornene resin C.

(Iv) Saturated norbornene resin D
The saturated norbornene compound (Tg: 181 ° C.) described in Example 1 of JP-T-8-507800 was used as the saturated norbornene resin D.

(V) Saturated norbornene resin E
APL6015T (Tg: 145 ° C.) manufactured by Mitsui Chemicals, Inc. was used as the saturated norbornene resin E.

(Vi) Saturated norbornene resin F
TOPAS 6013 (Tg: 130 ° C.) manufactured by Polyplastics Co., Ltd. was used as the saturated norbornene resin F.

(2) Film formation The saturated norbornene resins A to F were formed into cylindrical pellets having a diameter of 3 mm and a length of 5 mm. This was dried with a vacuum dryer at 110 ° C., the water content was adjusted to 0.1% or less, and then charged into a hopper adjusted to (Tg−10 ° C.).
The melt temperature is adjusted so that the melt viscosity becomes 1000 Pa · s, the melt is melted by using a single-screw kneader at this temperature for 5 minutes, and then extruded and extruded from a T-die set to 10 ° C. higher than the melt temperature. Was casted on a casting drum set to (Tg-5 ° C.) by heat treatment during the film forming process by the method shown in Table 2 to obtain a film.
At this time, touch roll film formation was performed under the conditions shown in Table 2. The solidified melt was peeled off and wound up. In addition, after trimming both ends (each 3% of the total width) just before winding, a thicknessing process (knurling) with a width of 10 mm and a height of 50 μm was applied to both ends, and a film with a width of 1.5 m was rolled at 3000 m at 30 m / min. I took it.

  None of the residual solvent of each film thus formed was observed. In addition, no foreign matter was observed.

(Evaluation)
About the obtained film, the temperature dependence (ΔRe temp, ΔRth temp) of Re, Rth, Re, Rth, and the temperature dependence distribution unevenness (ΔRe film, ΔRth film) of Re, Rth were measured according to the above-described methods. The results are shown in Table 2 below.
At this time, good performance was obtained with the embodiment of the present invention.

(3) Production of Polarizing Plate (3-1) Surface Treatment Each film was subjected to corona treatment so that the surface contact angle with water was 60 °.

(3-2) Production of Polarizing Film According to Example 1 of JP-A-2001-141926, a circumferential speed difference was given between two pairs of nip rolls, and a polarizing film having a thickness of 20 μm was prepared by stretching in the longitudinal direction.

(3-3) Bonding The following polarizing plate was produced in the same manner as in Example 1 described above.
Polarizing plate: saturated norbornene film / polarizing film / Fujitac

(3-4) Evaluation A 20-inch VA liquid crystal display device described in FIGS. 2 to 9 of JP-A No. 2000-154261 is obtained by using the polarizing plate thus obtained with the saturated norbornene film on the liquid crystal side. Attached to. This was displayed as a white display on the entire surface at high temperature (60 ° C.), and the area of color unevenness (light leakage) was visually measured to determine the ratio to the total area of the display portion.

表３中、熱処理方法の「Ａ」はキャスティングドラムを熱処理温度に設定したものであり、「Ｂ」は内部を熱処理温度雰囲気に設定した恒温槽を用いたものであり、「Ｃ」はフィルム両面からＩＲヒータを用いてフィルム表面を熱処理温度に加温したものである。

In Table 3, “A” in the heat treatment method is that in which the casting drum is set to the heat treatment temperature, “B” is to use a thermostatic bath in which the inside is set in the heat treatment temperature atmosphere, and “C” is on both sides of the film. The film surface is heated to a heat treatment temperature using an IR heater.

(8) Stretching The saturated norbornene film obtained by the melt film formation was subjected to the same conditions as in Example 1 except that the conditions shown in Table 4 were used. When this was incorporated into a liquid crystal display panel and evaluated in the same manner as described above, good performance was obtained.

(5) Production of optical compensation film An optical compensation film was produced in the same manner as in Example 1 described above. Good performance was obtained with the present invention.

(6) Production of low-reflection film A low-reflection film was produced in the same manner as in Example 1 described above, and good optical performance was obtained in the case of carrying out the present invention.

(7) Production of liquid crystal display device A liquid crystal display device was produced in the same manner as in Example 1 described above. What carried out the present invention was a good liquid crystal display device.

It is explanatory drawing which shows the measuring method of the temperature dependence distribution nonuniformity of Re and Rth. The schematic block diagram of the film manufacturing apparatus which manufactures the thermoplastic film in the case of performing long span stretching is shown. FIG. 3 is a perspective explanatory view of a longitudinally extending portion in FIG. 2. The schematic block diagram of the film manufacturing apparatus which manufactures the thermoplastic film in the case of performing short span stretching is shown. The perspective explanatory view of the longitudinal extension part of Drawing 4 is shown. It is explanatory drawing of the bowing generate | occur | produced with the manufacturing method which does not heat-set. It is explanatory drawing which shows suppression of generation | occurrence | production of the bowing by heat setting.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10, 10a Film manufacturing apparatus 12 Dryer 14 Extruder 16 Gear pump 18 Filter 20 Die 22 Cooling part 24 Touch roll 26 Touch roll 28 Cast drum 30, 30a Longitudinal stretch part 32 Inlet side nip roll 33 Preheating roll 34 Outlet side nip roller 35 Preheating roll 36 Preheating part 37 Nip roll 39 Nip roll 42 Lateral stretch part 44 Heat fixing part 46 Winding part Fa Unstretched film Fb Longitudinal stretched film F Thermoplastic film Lb curve

Claims (23)

  A method for producing a thermoplastic film, comprising: heat-treating an unstretched film formed by a melt film-forming method at a temperature of Tg to (Tg + 60 ° C.) at a conveyance tension of 0.1 kg / m to 20 kg / m ( The Tg represents the glass transition temperature of the unstretched film).   A film of Re ≦ 10 nm and Rth ≦ 30 nm obtained by stretching an unstretched film formed by the melt film forming method is heat-treated at a temperature of Tg to (Tg + 60 ° C.) with a transport tension of 0.1 kg / m to 20 kg / m. A method for producing a thermoplastic film characterized in that (Re represents in-plane retardation at 25 ° C. and 60% relative humidity, Rth represents retardation in the thickness direction at 25 ° C. and 60% relative humidity, The Tg represents the glass transition temperature of the unstretched film).   A thermoplastic film characterized by heat-treating an unstretched film having a residual solvent amount of 0.01% by mass or less at a temperature of Tg to (Tg + 60 ° C.) at a conveyance tension of 0.1 kg / m to 20 kg / m. (Tg represents the glass transition temperature of the unstretched film).   An unstretched film having a residual solvent amount of 0.01% by mass or less is stretched, and a film with Re ≦ 10 nm and Rth ≦ 30 nm is conveyed at a temperature of Tg to (Tg + 60 ° C.) at a transport tension of 0.1 kg / m A method for producing a thermoplastic film characterized by heat treatment at 20 kg / m (where Re represents in-plane retardation at 25 ° C. and 60% relative humidity, and Rth represents a thickness direction at 25 ° C. and 60% relative humidity) The Tg represents the glass transition temperature of the unstretched film). The manufacturing method of the thermoplastic film of any one of Claims 1-4 which perform the said heat processing for 1 second-60 minutes.   The method for producing a thermoplastic film according to any one of claims 1 to 5, wherein the heat treatment is performed during the melt film-forming step.   The manufacturing method according to any one of claims 1 to 6, wherein the unstretched film is formed using a touch roll method. A thermoplastic film characterized by satisfying the following formulas (1) and (2) and produced by a melt film-forming method.
Formula (1): Re ≦ 30 nm
Formula (2): ΔRetemp ≦ 10 nm
[In the above formula, Re represents in-plane retardation of the thermoplastic film at 25 ° C. and 60% relative humidity, ΔRe temp represents | Re-Re60 ° C., and Re 60 ° C. represents 60 ° C. of the thermoplastic film. -Represents in-plane retardation at 60% relative humidity. ] A thermoplastic film characterized by satisfying the following formulas (1) and (2) and having a residual solvent amount of 0.01% by mass or less.
Formula (1): Re ≦ 30 nm
Formula (2): ΔRe temp ≦ 10 nm
[In the above formula, Re represents in-plane retardation of the thermoplastic film at 25 ° C. and 60% relative humidity, ΔRe temp represents | Re-Re60 ° C., and Re 60 ° C. represents 60 ° C. of the thermoplastic film. -Represents in-plane retardation at 60% relative humidity. ] The thermoplastic film according to claim 8 or 9, wherein the following formulas (3) and (4) are satisfied.
Formula (3): | Rth | ≦ 30 nm
Formula (4): ΔRth temp ≦ 15 nm
[In the above formula, Rth represents retardation in the thickness direction at 25 ° C. and 60% relative humidity of the thermoplastic film, ΔRth temp represents | Rth−Rth60 ° C., and Rth60 ° C. represents 60 ° C. of the thermoplastic film] -Represents retardation in the thickness direction at a relative humidity of 60%. ] The thermoplastic film according to any one of claims 8 to 10, wherein the following formulas (5) and (6) are satisfied.
Formula (5): ΔRe film ≦ 5 nm
Formula (6): ΔRth film ≦ 5 nm
[In the above formula, ΔRe film represents the uneven distribution of ΔRe temp over the entire film surface of the thermoplastic film, and ΔRth film represents the uneven distribution of ΔRth temp over the entire film surface of the thermoplastic film. ΔRe temp represents | Re−Re60 ° C., Re represents in-plane retardation of the thermoplastic film at 25 ° C. and 60% relative humidity, and Re 60 ° C. represents 60 ° C. and 60% relative humidity of the thermoplastic film. In-plane retardation at. ΔRth temp represents | Rth−Rth60 ° C., Rth represents retardation in the thickness direction at 25 ° C. and relative humidity of 60% of the thermoplastic film, and Rth 60 ° C. represents 60 ° C. and relative humidity of 60% of the thermoplastic film. Represents retardation in the thickness direction. ] The thermoplastic film according to any one of claims 8 to 11, comprising cellulose acylate satisfying the following formulas (S-1) and (S-2).
Formula (S-1): 2.5 <= A + B <3.0
Formula (S-2): 1.25 ≦ B <3
(In the formula, A represents the degree of substitution of the acetyl group with respect to the hydrogen atom constituting the hydroxyl group of cellulose, and B represents the sum of the degree of substitution of the propionyl group, butynyl group and pentanoyl group with respect to the hydrogen atom constituting the hydroxyl group of cellulose.) The thermoplastic film according to any one of claims 8 to 11, comprising cellulose acylate having a composition satisfying the following formulas (T-1) and (T-2).
Formula (T-1): 2.5 <= A + C <3.0
Formula (T-2): 0.1 ≦ C <2
(In the formula, A represents the degree of substitution of the acetate group, and C represents a substituted or unsubstituted aromatic acyl group.)   The thermoplastic film according to claim 8, comprising a saturated norbornene resin. The thermoplastic film according to any one of claims 8 to 11, which has a retardation satisfying the following formulas (R-1) and (R-2).
Formula (R-1): 0 nm ≦ Re ≦ 150 nm
Formula (R-2): 0 nm ≦ Rth ≦ 300 nm
(In the formula, Re represents the in-plane retardation of the thermoplastic film, and Rth represents the thickness direction retardation of the thermoplastic film.) The thermoplastic film according to any one of claims 8 to 15, wherein the thermoplastic film is stretched with an aspect ratio L / W of more than 2 and 50 or less, or 0.01 to 0.3. . A thermoplastic film obtained by preheating the thermoplastic film according to any one of claims 8 to 16 at a temperature higher by 1 to 50 ° C than the stretching temperature before transverse stretching. A thermoplastic film obtained by heat-treating the thermoplastic film according to any one of claims 8 to 17 at a temperature lower by 1 ° C to 50 ° C than a stretching temperature after transverse stretching. The thermoplastic film according to any one of claims 8 to 18 is subjected to 0.1 kg / (Tg-50) ° C to (Tg + 30) ° C after at least one of longitudinal stretching and transverse stretching. A thermoplastic film characterized by heat relaxation while being conveyed with a tension of m to 20 kg / m.   The thermoplastic film according to any one of claims 8 to 19, which is produced by the method for producing a thermoplastic film according to any one of claims 1 to 7.   A polarizing plate comprising at least one thermoplastic film according to any one of claims 8 to 20.   An antireflection film comprising the thermoplastic film according to any one of claims 8 to 20.   A liquid crystal display device using at least one of the thermoplastic film according to any one of claims 8 to 20, the polarizing plate according to claim 21, and the antireflection film according to claim 22. .

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