JP4604386B2 - Optical film manufacturing method and manufacturing apparatus - Google Patents

Description

【００４６】
なお、表１中の比較例１は、請求項２の発明に対する比較例であり、比較例２は請求項５の発明に対する比較例である。
【００４７】
表１から明らかなように、製造されたフィルム(F)の面内レターデーション(R0)および面内レターデーション(R0)のばらつきは、実施例１〜６ものが比較例１〜３のものに比べて小さくなっている。また、製造されたフィルム(F)の表面凹凸も、実施例１〜６ものが比較例１〜３のものに比べて小さくなっている。
【００４８】
また、実施例７〜８の結果を表２に示す。
【００４９】
【表２】

【００５０】
表２から明らかなように、製造されたフィルム(F)の面内レターデーションは、実施例１〜６の場合よりもさらに小さくなるとともに均一になっている。
【００５１】
なお、表１および表２において、「残溶」とは残留溶媒量を意味するものである。
【００５２】
【発明の効果】
請求項１の発明によれば、支持体から剥離した第１テンター装置へ送るウェブの残留溶媒量を１０〜５０質量％として、ウェブを幅方向に延伸するとともに、第２テンター装置へ送るフィルムの残留溶媒量を０．１〜５質量％として、フィルムの幅を一定に保持、またはフィルムを幅方向に延伸しているので、従来の方法に比べて、面内レターデーションが小さくかつばらつきのない光学用フィルムを製造することができる。しかも、製造された光学用フィルムの表面凹凸は小さく、平面性に優れている。請求項６の発明によっても、これと同様な効果を奏する。
【図面の簡単な説明】
【図１】 この発明による方法を実施する装置の実施形態を示す概略構成図である。
【符号の説明】
(1)：支持体
(3)(4)：加熱乾燥装置
(5)：剥離ロール
(6)(8)：乾燥装置
(7)：第１テンター装置
(9)：第２テンター装置
(W)：ウェブ
(F)：フィルム[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a manufacturing method and a manufacturing apparatus for an optical film used for, for example, a protective film for a polarizing plate and an optical compensation film of a liquid crystal image display device.
[0002]
In this specification, the cast dope is dried on the support and after being in the form of a dope film that can be peeled off from the support, it is finally dried to form a film as a “web”. Shall be called.
[0003]
[Prior art]
A liquid crystal image display device can be directly connected to an IC circuit with a low voltage and low power consumption, and can be reduced in thickness, and thus is widely used as a display device for a word processor, a personal computer, or the like. By the way, the basic configuration of the liquid crystal image display device is one in which polarizing plates are provided on both sides of the liquid crystal cell. Since a polarizing plate allows only light of a polarization plane in a certain direction to pass, in a liquid crystal image display device, the polarizing plate plays an important role in visualizing changes in alignment due to an electric field. The performance of the image display device is greatly affected.
[0004]
The general structure of the polarizing plate is, for example, a cellulose ester film such as a cellulose triacetate film or a cellulose acetate propionate film on one or both sides of a polarizing film made of a polyvinyl alcohol film uniaxially stretched and iodine-stained by alkali saponification. The protective film which consists of is bonded together through adhesives, such as polyvinyl alcohol. Such a protective film is required not only to have excellent flatness but also to have small in-plane retardation and no variation.
[0005]
Conventionally, the cellulose ester film used as a protective film of a polarizing plate is manufactured by the method described in Unexamined-Japanese-Patent No. 4-152125 and Unexamined-Japanese-Patent No. 5-185445, for example.
[0006]
The method described in JP-A-4-152125 includes a step of casting a cellulose ester dope on a support, a step of drying the dope cast on the support and forming a web, and a web In the above-mentioned final drying step, a step of peeling the substrate from the support, a drying step of drying the peeled web, and a final drying step of further drying the web to obtain a film with a residual solvent amount of 10% by mass or less, In this method, the film is stretched 2 to 6% in the width direction. In this method, the residual solvent amount is represented by the formula {(A−B) / A} × 100. Here, A is the mass of the sample film, and B is the mass when A is dried with hot air at 110 ° C. for 1 hour.
[0007]
The method described in JP-A-5-185445 includes a step of casting a cellulose ester dope on a support, a step of drying the dope cast on the support and forming a web, and a web A step of peeling the web from the support, a roll drying step of drying and peeling the peeled web on a drying roll, and stretching and drying the web while gripping and feeding the edges in the width direction in the tenter drying device. When the residual solvent amount (represented by the same formula as the method described in JP-A-4-152125) when the web is peeled from the support is 68% by mass or more. In this method, the drying temperature for at least 20 seconds after peeling is 30 to 80 ° C.
[0008]
[Problems to be solved by the invention]
However, the method described in JP-A-4-152125 has the following problems. That is, in the final drying step in which the residual solvent amount is 10% or less, drying at a high temperature for a long time is required, and softening due to heat and elongation due to tension occur. Further, the in-plane retardation control by stretching needs to be performed at the end of the final drying step. However, if the stretching is performed at a stretching ratio of 2 to 6% at the end of the final drying step, the in-plane letter of the obtained film is controlled. The dispersion of the foundation becomes large.
[0009]
The method described in JP-A-5-185445 has the following problems. That is, when the amount of residual solvent when the web is peeled off from the support is 68% by mass or more, the web is a soft film, so that the web is slackened or fluttered during conveyance in the roller drying process, and the conveyance is not performed. Become stable. When the conveyance tension is increased in order to realize stable conveyance, the web is stretched in the conveyance direction and contracted in the width direction, and as a result, the in-plane retardation of the obtained film is increased. Further, in the tenter drying step, drying, that is, reduction of the residual solvent amount and stretching are performed at the same time, resulting in variations in in-plane retardation of the obtained film.
[0010]
In addition, in any of the methods, since the residual solvent amount of the web during stretching is small, in order to control in-plane retardation only by this stretching, the motion sensitivity of in-plane retardation with respect to the stretching amount is high. Therefore, it is difficult to control the in-plane retardation.
[0011]
And in any method, the obtained film cannot be used for an optical film. In particular, in the case of a protective film for a polarizing plate or an optical compensation film of a liquid crystal image display device, if the in-plane retardation varies or increases, the performance of the liquid crystal image display device is greatly adversely affected.
[0012]
An object of the present invention is to solve the above-described problems and provide an optical film manufacturing method and manufacturing apparatus that have a smaller in-plane retardation and no variation compared to conventional methods.
[0013]
[Means for Solving the Problems]
The method for producing an optical film according to the first aspect of the present invention includes a step of casting a dope of a raw material resin of an optical film on a support, and drying the dope cast on the support to form a web. A step of peeling the web from the support, and feeding the peeled web to the first tenter device. The first tenter device grips both side edges in the width direction of the web and stretches the web in the width direction. a step of, obtaining a film by drying the web, send the film to the second tenter device, grips the widthwise side edges of the film at the second tenter apparatus, the width of the film constant holding, or film a method of producing an optical film for a and a step of stretching in the width direction, the residual solvent amount web to be sent to the first tenter apparatus is 10 to 50 wt%, and sends it to the second tenter device film The residual solvent amount is characterized in that it has 0.1 to 5 mass%.
[0014]
The residual solvent amount according to the present invention is different from the residual solvent amount in the conventional method described above, and is expressed by the following formula in all cases.
[0015]
Residual solvent amount (% by mass) = {(XY) / Y} × 100
Here, X is the mass of the web at any point in time, and Y is the mass when the X web is dried at 110 ° C. for 3 hours. In the following description, the residual solvent amount means that which is met by the above formula.
[0016]
According to a second aspect of the present invention, there is provided a method for producing an optical film according to the first aspect of the present invention, wherein the web is dried on the support until the residual solvent amount reaches 70 to 160% by mass, and then the web is supported. It peels from. Here, the residual solvent amount of the web to be peeled off from the support is limited to 70 to 160% by mass. In order to reduce the residual solvent amount to less than 70% by mass, the drying load on the support must be increased. However, in practice, it is difficult to raise the drying temperature until the residual solvent amount is less than 70% by mass. Further, if the residual solvent amount of the web to be peeled exceeds 160% by mass, the web becomes soft and the web stretches when peeled from the support, and in severe cases the web may be broken. .
[0017]
In claim 1, the amount of residual solvent of the web sent to the first tenter device is limited to 10 to 50% by mass, if the residual solvent amount is less than 10% by mass, the residual by stretching in the first tenter device This is because the stress increases and the shrinkage in the width direction in the subsequent drying process increases, so that the stretch ratio in the second tenter apparatus must be increased. Further, if the residual solvent amount exceeds 50% by mass, the change in the in-plane retardation due to stretching in the first tenter device becomes small, and it may be difficult to control the in-plane retardation.
[0018]
In the said Claim 1 , the amount of residual solvents of the film sent to a 2nd tenter apparatus shall be 5 mass% or less. This is because if the residual solvent amount exceeds 5% by mass, the degree of drying in the second tenter apparatus must be increased, and the variation in in-plane retardation may increase. The lower limit of the residual solvent amount of the film to be sent to the second tenter apparatus is determined in consideration of productivity, cost, etc., but is 0.1% by mass, preferably 0.01% by mass.
[0019]
The method for producing an optical film according to the invention of claim 3 is the method according to claim 1 or 2 , wherein the treatment temperature in the second tenter device is set within a range of ± 50 ° C. of the glass transition temperature of the raw resin, and stretched. The rate is set to 0 to 3%. Here, the treatment temperature in the second tenter device is limited to the range of ± 50 ° C. of the glass transition temperature of the raw resin, which enables uniform stretching in the width direction of the film , and the residual stress after stretching This is because an increase can be suppressed and a dimensional change can be reduced. Further, the reason why the stretching ratio in the second tenter apparatus is limited to 0 to 3% is that if it exceeds 3%, the in-plane retardation may be different between the central portion and the side edge portions of the film width. .
[0020]
Here, the case where the stretching ratio is 0% means that the film width is kept constant, and the case where it is larger than 0% means that the film is stretched in the width direction.
[0021]
According to a fourth aspect of the present invention, there is provided a method for producing an optical film, comprising: measuring the in-plane retardation of the web that has passed through the first tenter device according to any one of the first to third aspects; Thus, the stretching ratio in the first tenter device is controlled. In this case, the in-plane retardation of the web that has passed through the first tenter device can be set to the target value, and as a result, the stretching ratio in the second tenter device can be suppressed to a certain range, and obtained. Uniformity of in-plane retardation of the film can be ensured.
[0022]
The method for producing an optical film according to the invention of claim 5 is the invention according to any one of claims 1 to 4, wherein the web peeled from the support is measured in the transport direction and width direction, before and after the first tenter device. Measure the dimensions of the web in the conveyance direction and the width direction, and the dimensions in the conveyance direction and the width direction of the film before and after the second tenter device, and use the dimensions of the web peeled from the support as a reference. The dimension ratios in the transport direction and the width direction before and after the apparatus and before and after the second tenter apparatus are set to 0.9 to 1.1, respectively.
[0023]
In the invention of claim 5 , the dimension in the conveyance direction of the web or film refers to the distance between two marks applied by inkjet at a predetermined interval in the conveyance direction on the support. It is measured as follows. That is, a measurement roll on which a web or a film is hung is provided at each measurement location, the two marks passing through the measurement roll are observed with a CCD to obtain a passing time, and the web is further measured based on the number of rotations of the measurement roll. Alternatively, the speed at which the film passes through the measurement roll is obtained, and the distance between the two marks is obtained from the passage time and the passage speed. In addition, the dimension of the width direction of a web or a film is calculated | required by observing with CCD in each measurement location.
[0024]
Here, the reason why the dimensional ratio is limited to 0.9 to 1.1 is that in-plane retardation may be increased if the ratio is out of the above range. The dimensional ratio is more preferably 0.95 to 1.05.
[0025]
An apparatus for producing an optical film according to a sixth aspect of the invention forms a web by drying a support, a die for casting a dope of a raw resin on the support, and a dope cast on the support. a heating drying device, a stripping roll to peel the web from the support, is peeled web is sent to residual solvent amount in the 10 to 50 mass%, gripping the widthwise side edges of the web, c E A first tenter device that stretches the web in the width direction, a drying device that dries the web until the amount of residual solvent is 0.1 to 5% by mass, and grips both side edges of the film in the width direction And a second tenter device for keeping the film width constant or stretching the film in the width direction.
[0026]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0027]
FIG. 1 shows an apparatus for carrying out the method of the invention.
[0028]
In FIG. 1, an apparatus for producing a cellulose ester film includes a support (1) made of a metal endless belt having a mirror-finished surface, and a dope for casting a cellulose ester dope on the support (1). Heat drying to form a web by heating and drying the dope cast on the casting die (2) and both sides of the upper and lower transfer paths of the support (1) and cast on the support (1) Apparatus (3) (4), web peeling roll (5) for peeling web (W) from support (1), and first drying device for drying web (W) peeled from support (1) (6) and a first tenter device that holds both sides of the dried web (W) in the width direction so as to keep the width of the web (W) constant or stretch the web (W) in the width direction ( 7) and a second drying device (8) for further drying the web (W) whose width is regulated by the first tenter device (7) to obtain a film, A second tenter device (9) that holds both sides of the film (F) in the width direction to hold the film (F) width constant or stretch the film (F) in the width direction; And a film winding device (10) for winding the film (F). In addition, as a support body, it may replace with a metal endless belt and you may use what consists of metal drums.
[0029]
The first drying device (6) and the second drying device (8) have the same configuration, and housings (60), (80) having hot air blowing ports (61) (81) and discharge ports (62) (82), respectively. ), A plurality of transport rolls (63) and (83) are provided in a staggered arrangement. In both dryers (6) and (8), the web (W) is hung on all the transport rolls (63) and (83) in the housing (60) and (80), and hot air is blown during the transport. It is dried by dry hot air blown from the mouth (61) (81). The film winding device (10) includes a plurality of transport rolls (101) and one winding roll (102) provided in a housing (100). Then, the film (F) sent from the second tenter device (9) is hung on all the transport rolls (101) in the housing (100), and is taken up by the take-up roll (102). .
[0030]
In the above, the conveying rolls (63) and (83) of both drying apparatuses (6) and (8) are provided in a staggered arrangement, but the present invention is not limited to this, and the arrangement of the conveying rolls (63) and (83) This method can be changed as appropriate. In place of the transport rolls (63) and (83), an air roll, a floating nozzle, or the like may be used.
[0031]
Further, in the above, as the both tenter devices (7) and (9), a normal uniaxial tenter device or a biaxial tenter device using a linear motor capable of setting an expansion / contraction amount independently in the width direction and the conveyance direction is used. It is possible. When a single-axis tenter device is used, it is necessary to change the tension in the front and back to control the expansion and contraction in the transport direction within the tenter device. However, when a biaxial tenter device is used, Control of expansion and contraction in the transport direction can be easily performed.
[0032]
The manufacturing method of the cellulose ester film (F) using the manufacturing apparatus having the above-described configuration is as follows.
[0033]
First, a cellulose ester dope is cast from a casting die (2) onto a support (1) and dried by a heat drying device (3) (4) until the residual solvent amount is 70 to 160% by mass. Thus, the web (W) is formed on the support (1). Next, the web (W) formed on the support (1) is peeled off from the support (1) by the peeling roll (5), and the peeled web (W) is removed from the housing of the first drying device (6) ( Send within 60). In the first drying device (6), the web (W) is hung on a plurality of transport rolls (63) and transported in the housing (60). During this transport, the hot air blown from the hot air blowing port (61) is used to dry the web (W). It is made to dry and it is made to dry until the amount of residual solvents becomes 10-50 mass%. Next, the web (W) is fed to the first tenter device (7), where the both lateral edges of the web (W) are held, and the width of the web (W) is kept constant, or the web (W ) In the width direction and dried by heating. The stretch ratio in the first tenter device (7) is preferably 0 to 8%, and the residual solvent amount of the web (W) that has passed through the first tenter device (7) is preferably 5 to 20% by mass.
[0034]
Next, the web (W) whose width is restricted is fed into the housing (80) of the second drying device (8), and the web (W) is hung on a plurality of transport rolls (83) to move inside the housing (80). The film (F) is obtained by transporting and drying with hot dry air blown from the hot air blowing port (81) during the transfer until the residual solvent amount becomes 0.1 to 5% by mass. Next, this film (F) is sent to the second tenter device (9) where the stretch ratio is 0 to 3% at a temperature within the range of ± 50 ° C. of the glass transition temperature of the cellulose ester as the raw material. Stretch. The residual solvent amount of the film (F) whose width is regulated by the second tenter device (9) is 2% by mass or less. Even when the amount of residual solvent in the film (F) sent to the second tenter device (9) exceeds 2% by mass, the second tenter device (9) is heated during stretching, The amount of residual solvent is 2% by mass or less. Finally, the film (F) whose width has been regulated is sent to the film winding device (5), hung on the plurality of conveying rolls (101), conveyed, and then wound on the winding roll (102). Thus, the cellulose ester film (F) is produced.
[0035]
In the manufacturing method of the above embodiment, the in-plane retardation of the web (W) that has passed through the first tenter device (7) is measured by, for example, an online birefringence measuring device KOBLA-311 series manufactured by Oji Scientific Instruments, Based on this measured value, the stretching ratio in the first tenter device (7) may be feedback controlled.
[0036]
Further, in the manufacturing method of the above embodiment, the web (W) peeled from the support (1) in the carrying direction and the width direction, and the web (W) carrying direction before and after the first tenter device (7). Measure the dimensions of the web (W) peeled from the support (1) by measuring the dimensions in the width direction and the dimensions of the transport direction and width direction of the film (F) before and after the second tenter device (9). As a reference, the dimensional ratio in the conveying direction and the width direction before and after the first tenter device (7) and before and after the second tenter device (W) is 0.9 to 1.1, preferably 0.95 to 1. You may make it set to 05. That is, the web (W) formed on the support (1) is marked with two marks at a predetermined interval in the transport direction by ink jet, and further on the downstream side of the peeling roll (5), the first Measurement (not shown) in which the web (W) or film (F) is put on the front and back (upstream and downstream) of the tenter device (7) and on the front and back (upstream and downstream) of the second tenter device (9), respectively. A roll is provided, and the two marks passing through the measurement roll are observed with a CCD to determine the passage time. Further, the web (W) or film (F) passes through the measurement roll based on the number of rotations of the measurement roll. The distance between the two marks is obtained from the passage time and the passage speed, which is taken as the dimension in the conveyance direction, and the dimension in the conveyance direction of the web (W) peeled from the support (1). 1st tenter with 1 The dimensional ratios in the conveying direction before and after the before and after and the second tenter device of the apparatus (7) (W), respectively set in the above range. Further, in the above-described measurement roll portion, the width (W) or film (F) dimension in the width direction of the web (W) is obtained by observing with a CCD, and the dimension of the web (W) peeled off from the support (1) is used as a reference. As described above, the dimension ratio in the width direction before and after the first tenter device (7) and before and after the second tenter device (W) is set within the above range.
[0037]
Hereinafter, specific examples of the present invention will be described together with comparative examples.
[0038]
Examples 1-6 and Comparative Examples 1-4
Aerosil 200V (manufactured by Nippon Aerosil Co., Ltd.) 1 kg and ethanol 9 kg were stirred and mixed in a dissolver for 30 minutes, and then dispersed using a Manton Gorin type high-pressure dispersion device to prepare a silicon oxide dispersion. Next, 6 kg of cellulose triacetate (acetyl substitution degree 2.88) and 140 kg of methylene chloride were put into a sealed container, and 10 kg of the above silicon oxide dispersion was added with stirring, and the mixture was further stirred for 30 minutes, filtered and added. A liquid was prepared.
[0039]
And the following ingredients:
Cellulose triacetate (acetyl substitution degree 2.88)
100kg
440 kg of methylene chloride
Ethanol 38kg
Triphenyl phosphate 8kg
Ethyl phthalyl ethyl glycolate 2kg
Tinuvin 326 0.3kg
Tinuvin 109 0.5kg
Tinuvin 171 0.5kg
Of these, the solvent was put into a sealed container, the remaining one was added while stirring, and the mixture was heated and stirred to dissolve completely. Next, the temperature of this solution was lowered to the dope casting temperature and allowed to stand overnight, and after defoaming operation, this solution was filtered using Azumi filter paper No. 244 manufactured by Azumi Filter Paper Co., Ltd. Further, 2 kg of the above additive solution was added to this solution, mixed well with an in-line mixer (manufactured by Toray Industries, Inc., a static in-tube mixer Hi Mixer SWJ), and filtered to prepare a dope.
[0040]
Using the obtained dope, a cellulose ester film (F) was produced under various conditions using the apparatus shown in FIG. That is, the residual solvent amount of the web (W) peeled off from the support (1), the residual solvent amount of the web (W) after passing through the first drying device (6), and the first tenter device (7). Stretch rate and stretch temperature, residual amount of web (W) passed through the first tenter device (7), drying temperature in the second drying device (8), obtained through the second drying device (8) The cellulose ester film (F) having a film thickness of 80 μm and a residual solvent amount of 2% by mass or less was obtained by varying the amount of residual solvent of the film (F) and the stretching rate and stretching temperature in the second tenter device (9). Manufactured.
[0041]
In the case of Comparative Example 2, the film (9) was broken in the second tenter device (9).
[0042]
Examples 7-8
Dimensions of the web (W) peeled from the support (1) in the conveyance direction and the width direction, the dimension of the web (W) in the conveyance direction and the width direction before and after the first tenter device (7), and the second tenter device The dimensions of the film (F) before and after (9) are measured in the conveyance direction and width direction, and the dimension of the web (W) peeled from the support (1) is taken as 1, and the first tenter device (7) The dimensional ratios in the transport direction and the width direction before and after the front and rear and the second tenter device (W) are set in the range of 0.9 to 1.1, respectively. A cellulose ester film (F) having a thickness of 80 μm and a residual solvent amount of 2% by mass or less was produced.
[0043]
Evaluation Test The in-plane retardation (R0) of the films (F) obtained in Examples 1 to 6 and Comparative Examples 1 to 4 was measured using an on-line birefringence measuring device KOBLA-311 manufactured by Oji Scientific Instruments. Further, the surface irregularity of the obtained film (F) was measured with a laser displacement meter manufactured by Keyence Corporation.
[0044]
The results of Examples 1 to 7 and Comparative Examples 1 to 4 are shown in Table 1.
[0045]
[Table 1]

[0046]
Comparative Example 1 in Table 1 is a comparative example for the invention of claim 2, and Comparative Example 2 is a comparative example for the invention of claim 5.
[0047]
As is apparent from Table 1, the variations in the in-plane retardation (R0) and in-plane retardation (R0) of the produced film (F) were changed from those in Examples 1 to 6 to those in Comparative Examples 1 to 3. It is smaller than that. Moreover, the surface unevenness | corrugation of the manufactured film (F) is also small in Examples 1-6 compared with the thing of Comparative Examples 1-3.
[0048]
The results of Examples 7 to 8 are shown in Table 2.
[0049]
[Table 2]

[0050]
As is clear from Table 2, the in-plane retardation of the produced film (F) is smaller and uniform than in the case of Examples 1-6.
[0051]
In Tables 1 and 2, “residual solution” means the amount of residual solvent.
[0052]
【The invention's effect】
According to the first aspect of the present invention, the residual solvent amount of the web sent to the first tenter device peeled from the support is set to 10 to 50% by mass, the web is stretched in the width direction, and the film sent to the second tenter device is sent. Since the residual solvent amount is 0.1 to 5% by mass and the film width is kept constant or the film is stretched in the width direction, the in-plane retardation is small and no variation compared to the conventional method. An optical film can be produced. And the surface unevenness | corrugation of the manufactured optical film is small, and it is excellent in planarity. According to the sixth aspect of the invention, the same effect can be obtained.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram showing an embodiment of an apparatus for carrying out a method according to the present invention.
[Explanation of symbols]
(1): Support
(3) (4): Heating and drying equipment
(5): Release roll
(6) (8): Drying equipment
(7): First tenter device
(9): Second tenter device
(W): Web
(F): Film

Claims (6)

A step of casting a dope of a raw material resin for an optical film on a support, a step of drying a dope cast on the support to form a web, a step of peeling the web from the support, and a peeling and to send a web first tenter device, grips the widthwise side edges of the web in the first tenter device, a step of stretching the web in the width direction, obtaining a film by drying the web sends a film to the second tenter apparatus, including at a second tenter device grips the widthwise side edges of the film, and a step of stretching retain the width of the film constant, or a film in the width direction A method for producing an optical film, wherein the residual solvent amount of the web sent to the first tenter device is 10 to 50% by mass, and the residual solvent amount of the film sent to the second tenter device is 0.1 to 5% by mass. With features That, production method of an optical film.   The method for producing an optical film according to claim 1, wherein the web is formed by drying until the residual solvent amount is 70 to 160% by mass on the support, and then the web is peeled from the support. The process for producing a film for an optical film according to claim 1 or 2, wherein the treatment temperature in the second tenter device is within a range of ± 50 ° C of the glass transition temperature of the raw material resin, and the stretch ratio is 0 to 3%. Method. The optical film according to any one of claims 1 to 3, wherein an in-plane retardation of the web that has passed through the first tenter device is measured, and a stretching ratio in the first tenter device is controlled based on the measured value. Manufacturing method. Dimensions in the transport direction and width direction of the web peeled from the support, web transport direction and width dimension before and after the first tenter device, and film transport direction and width direction before and after the second tenter device The dimension ratios in the transport direction and the width direction before and after the first tenter device and before and after the second tenter device are respectively 0.9-1. The manufacturing method of the optical film in any one of Claims 1-4 set to 1 . A support, a die for casting a dope of a raw material resin on the support, a heat drying apparatus for drying the dope cast on the support to form a web, and a peeling roll for peeling the web from the support And the first tenter device, in which the peeled web is fed at a residual solvent amount of 10 to 50% by mass, grips both side edges of the web in the width direction, and stretches the web in the width direction; , A drying device for obtaining a film by drying until the residual solvent amount is 0.1 to 5% by mass, and holding both side edges in the width direction of the film to keep the film width constant, or the film in the width direction An optical film manufacturing apparatus comprising: a second tenter device for stretching.

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