Film roll, manufacturing method thereof, polarizing plate, and display device

Abstract

To provide a film roll with no sticking failure even during long-term storage, a method for manufacture of the same, a polarizer, and a display device.SOLUTION: In a film roll with no knurling processing part, when a thickness of a void layer between films adjacent to each other at a winding core peripheral part that is measured at a width direction side part is represented by X[μm], and a thickness of a void layer between films adjacent to each other at a winding outer peripheral part is represented by Y[μm], X and Y satisfy the following formula (1): X<Y.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a film roll, a method for producing the same, a polarizing plate, and a display device. More specifically, the present invention relates to a film roll that is free from misalignment during transportation and free from sticking problems even during long-term storage. [Background technology]

[0002] In recent years, due to the fierce price competition in the LCD TV market, polarizing plate manufacturers have been considering cost-cutting measures such as reducing switching losses, and in response to this, the films used in polarizing plates have been becoming longer.

[0003] By making the film longer, it is possible to reduce costs in various aspects, such as splicing loss, inspection labor hours, transportation, and auxiliary materials, and the film is usually wound into rolls after production for convenience in storage and transportation.

[0004] However, particularly in the case of long film rolls, misalignment can occur during transport, and if the film roll is stored for a long period of time, air can escape between the films, causing sticking problems.

[0005] One possible solution to the above problem would be to wind the protective film together with the film, but this would result in the protective film becoming waste.

[0006] One possible way to solve the above problem without generating waste is to knurl the edges of the film in advance, and then trap air between the films when they are wound up, thereby forming an air gap layer (also called an "air layer") of an appropriate thickness, which prevents the films from sticking together. However, the knurling method is less effective at preventing sticking than winding the film together with the protective film, and there is a problem that sticking problems are more likely to occur, especially in the outer part of the winding, as air escapes between the films over time. Furthermore, if the gap layer is formed thick to prevent the above-mentioned sticking failure, there is a problem that the winding may become misaligned during transportation of the product.

[0007] Patent Document 1 discloses a method for forming an air layer of an appropriate thickness by changing the magnitude of the winding tension and the height of the knurling at the film end in accordance with the winding diameter of the film roll when winding the film, thereby keeping the amount of air taken in between the film constant. However, there is still room for improvement in order to solve the above problems.

[0008] In this specification, the term "void layer" refers to a layer formed by the gap between the opposing surfaces of adjacent films in a film roll, in which air or substances other than air (for example, gases such as inert gases) may exist. Strictly speaking, the layer formed by the air in this "void layer" is called the "air layer," but when not distinguishing between the two does not particularly affect the present invention, the "air layer" will be referred to as the "void layer." Another example of a porous layer is when the minute uneven convex portions on the surface of one of the adjacent films are in contact with the surface of the other opposing film in places. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-46966 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been made in consideration of the above problems and circumstances, and the problem to be solved is to provide a film roll that does not slip during transportation and does not stick even when stored for a long period of time, a method for manufacturing the same, a polarizing plate, and a display device. [Means for solving the problem]

[0011] In order to solve the above-mentioned problems, the inventors of the present invention have studied the causes of the above-mentioned problems and have found that it is possible to reduce the thickness of the gap layer between the films at the outer periphery of the film roll without knurling the film roll. core The inventors have found that the above problem can be solved by making the thickness of the air gap layer thicker than that of the peripheral portion, and have arrived at the present invention. That is, the above-mentioned problems of the present invention are solved by the following means.

[0012] 1. A film roll having no knurled portion, wherein the thickness of the gap layer between adjacent films at the periphery of the core measured at the side surface in the width direction of the film roll is X [μm], and the thickness of the gap layer between adjacent films at the outer periphery of the roll is Y [μm], and X and Y satisfy the relationship of the following formula (1): death, The X [μm] and the Y [μm] satisfy the following formula (2) and formula (3). A film roll characterized by:

[0013] Formula (1) <Y Equation (2) 0.15< X <0.40 Equation (3) 1<(Y / X)≦3

[0016] 2 A method for producing a film roll that does not have a knurled portion, wherein the thickness of the gap layer between adjacent films in the peripheral portion of the winding core measured at the side portion in the width direction of the film roll is X [μm], and the thickness of the gap layer between adjacent films in the outer peripheral portion of the winding is Y [μm], and X and Y satisfy the relationship of the following formula (1): death, The X [μm] and the Y [μm] satisfy the following formula (2) and formula (3). The method for producing a film roll is characterized by adjusting the temperature so as to

[0017] Formula (1) <Y Equation (2) 0.15< X <0.40 Equation (3) 1<(Y / X)≦3

[0020] 3The film touch pressure at the peripheral portion of the winding core is adjusted within a range of 6 to 55 [N / m], the film touch pressure at the center of the winding is adjusted within a range of 4 to 40 [N / m], and the film touch pressure at the outer peripheral portion of the winding is adjusted within a range of 3 to 30 [N / m]. In item 2 A method for producing the film roll described above.

[0021] 4 .1st In the section A polarizing plate comprising a part of the film from the film roll described above.

[0022] 5 .1st In the section A display device comprising a part of the film from the film roll described above. [Effects of the Invention]

[0023] The above-described means of the present invention can provide a film roll that is free from misalignment during transportation and free from sticking problems even during long-term storage, a method for producing the same, a polarizing plate, and a display device. The mechanism by which the effects of the present invention are manifested or the mechanism of action is not clear, but is speculated as follows.

[0024] The film roll of the present invention is not subjected to knurling processing, and the thickness of the gap layer between the films at the outer periphery of the winding is made thicker than the thickness of the gap layer at the periphery of the winding core, so that the film does not slip during transportation and can be prevented from sticking together even during long-term storage.

[0025] In conventional film rolls that have been knurled, the film is supported only by the knurled parts, so the restricting force to prevent misalignment is applied to the knurled parts. This causes uneven stress on the film, which results in more air escaping between the film, especially on the outside of the roll, and the thickness of the void layer becomes uneven, which can lead to sticking and failure during long-term storage.

[0026] In contrast, the film roll of the present invention does not have any knurled portions, and the film is supported by the entire tiny contact surface between the films, and the void layer is thicker on the outside of the roll than on the core side.Therefore, even if the amount of air escaping between the films increases on the outside of the roll during long-term storage, the thickness of the void layer is less likely to become uneven, and it is presumed that the stress applied to the film is uniform, thereby eliminating sticking problems.

[0027] The above-mentioned "microscopic contact surface between films" will now be explained. Although the film roll of the present invention is not knurled, the film surface usually has minute irregularities of nanometer size, so that the numerous protrusions on the opposing surfaces of adjacent films come into contact with each other's surfaces in places, and the entire tiny contact surface of the protrusions supports the film.

[0028] That is, for example, because some of the convex portions are in contact with each other, the films may be supported not only by a gap layer, such as an air layer, but also by multiple contact points caused by the minute concaves and convexes.

[0029] Here, the inertial force acting in the width direction of the film roll (longitudinal direction of the core) during transportation of the film roll will be considered.

[0030] Figure 1 is a conceptual diagram of the inertial force acting in the width direction of the film roll on the film near the core side, and Figure 2 is a conceptual diagram of the inertial force acting in the width direction of the film roll on the film near the outside of the winding.

[0031] The core is designated as R, and the film wound around the film roll (30) closest to the core (R) is designated as F. in The film near the outside of the winding is F out As can be seen from Figures 1 and 2, the film (F in ) contains the film (F in ) is subjected to an inertial force equal to the mass of the film layer (L1) wound on the outside of the winding, but the film (Fout ) contains the film (F out ) only experiences an inertial force equal to the mass of the film layer (L2) wound on the outside of the roll.

[0032] From the above, the film (F in ) has the film near the outside of the winding (F out ) will act on the film, and since the inertial force is proportional to the mass, in ) contains the film (F out ) will act as a larger inertial force than the winding force acting on the core, making it more likely that misalignment will occur on the core side.

[0033] In contrast, in the film roll of the present invention, the thickness of the gap layer between the films at the outer periphery of the winding is made thicker than the thickness of the gap layer between the films at the periphery of the winding core. This makes the frictional force acting between the films at the periphery of the winding core relatively greater than that at the outer periphery of the winding, thereby balancing out the large inertial force acting on the winding core side as described above, and is thought to have made it possible to prevent winding slippage on the winding core side as described above. [Brief explanation of the drawings]

[0034] [Figure 1] Conceptual diagram of the inertial force acting on the film near the core in the width direction of the film roll [Figure 2] Conceptual diagram of the inertial force acting on the film near the outside of the roll in the width direction [Figure 3] Schematic diagram showing the positional relationship between the side surface of the film roll in the width direction and the imaging device. [Figure 4] Schematic diagram of a side surface in the width direction of a film roll as viewed from a plane perpendicular to the side surface. [Figure 5] Processed image for calculating the thickness of the void layer [Figure 6] A simplified conceptual diagram of a part of the side surface in the width direction of a film roll to illustrate the periphery of the winding core, the center of the winding, and the outer periphery of the winding. [Figure 7] Schematic diagram of the internal structure of the imaging unit [Figure 8] Schematic diagram of the system configuration of the imaging device [Figure 9] Flowchart showing the manufacturing process of the solution casting film-forming method [Figure 10] Schematic diagram of an apparatus for producing film by the solution casting method [Figure 11] FIG. 1 is a plan view schematically illustrating the internal configuration of a tenter stretching device. [Figure 12] A plan view showing the state where the cover of the tenter stretching device is removed. [Figure 13] Schematic diagram of the nozzle and heater installation area when viewing the three zones inside the tenter stretching machine from the front [Figure 14] Side view of the three zones within the tenter stretching unit [Figure 15] 1 is a schematic diagram showing the film winding process and the cross section of the film roll of the present invention after winding. [Figure 16] Flowchart showing the manufacturing process of the melt casting film production method [Figure 17] Schematic diagram of a device for producing film using the melt-casting film-making method [Figure 18] 1 is a schematic diagram showing an example of the configuration of a liquid crystal display device of the present invention; [Figure 19] Conceptual diagram showing the amount of misalignment between the left and right edges of the film roll in the width direction DETAILED DESCRIPTION OF THE INVENTION

[0035] The film roll of the present invention is a film roll that does not have a knurled portion, and is characterized in that, when the thickness of the gap layer between adjacent films at the periphery of the winding core, measured at the side portion in the width direction of the film roll, is X [μm] and the thickness of the gap layer between adjacent films at the outer periphery of the winding is Y [μm], X and Y satisfy the relationship of formula (1). The above features enable the problem of the present invention to be solved.

[0036] Furthermore, the film roll manufacturing method of the present invention is a method for manufacturing a film roll that does not have a knurled portion, and is characterized in that, when the thickness of the gap layer between adjacent films in the peripheral portion of the winding core, measured at the side portion in the width direction of the film roll, is X [μm] and the thickness of the gap layer between adjacent films in the outer peripheral portion of the winding is Y [μm], X and Y are adjusted to satisfy the relationship of formula (1). The above two features are technical features common to or corresponding to the following embodiments (modes).

[0037] As an embodiment of the present invention, it is preferable that the X [μm] and the Y [μm] satisfy the formula (2) and the formula (3) from the viewpoint of preventing misalignment during transportation and preventing sticking during long-term storage.

[0038] It is preferable to adjust the X [μm] and Y [μm] so as to satisfy the formula (2) and the formula (3) from the viewpoint of preventing misalignment during transportation and sticking during long-term storage.

[0039] It is preferable to adjust the film touch pressure around the core periphery within the range of 6 to 55 [N / m], the film touch pressure around the center of the winding within the range of 4 to 40 [N / m], and the film touch pressure around the outer periphery of the winding within the range of 3 to 30 [N / m] to prevent misalignment during transport and to prevent sticking during long-term storage.

[0040] A part of the film in the film roll of the present invention can be suitably used when it is provided in a polarizing plate.

[0041] A part of the film in the film roll of the present invention can be suitably used when it is provided in a display device.

[0042] The present invention, its components, and embodiments for carrying out the present invention will be described in detail below. In this application, the symbol "to" is used to mean that the numerical values ​​before and after it are included as lower and upper limits.

[0043] 1. Film roll (1.1) Film Roll Overview The film roll of the present invention is a film roll that does not have a knurled portion, and is characterized in that, when the thickness of the gap layer between adjacent films at the periphery of the winding core, measured at the side portion in the width direction of the film roll, is X [μm] and the thickness of the gap layer between adjacent films at the outer periphery of the winding is Y [μm], X and Y satisfy the relationship of the following formula (1):

[0044] Formula (1) <Y

[0045] In the film roll of the present invention ("film roll" refers to a film wound into a roll), the thickness of the gap layer between the films at the outer periphery of the winding is made thicker than the thickness of the gap layer at the periphery of the winding core, so that the frictional force acting on the film on the winding core side is increased, making it possible to prevent misalignment of the winding during transportation, particularly at the periphery of the winding core.

[0046] Furthermore, there are no knurled portions, and as mentioned above, the film is supported by the entire tiny contact surface between the films, and the void layer is thicker on the outside of the reel than on the core side. Therefore, even if the amount of air escaping between the films increases on the outside of the reel during long-term storage, the thickness of the void layer does not become uneven, and the stress applied to the film is uniform, eliminating sticking failures.

[0047] As an embodiment of the present invention, it is preferable that the X [μm] and the Y [μm] satisfy the formula (2) and the formula (3) from the viewpoint of preventing misalignment during transportation and preventing sticking during long-term storage.

[0048] (1.2) Air gap between films (1.2.1) Means for controlling the thickness of the air gap layer The film roll of the present invention has a void layer that is thicker at the outer periphery of the winding to allow in an appropriate amount of air, thereby relatively increasing the frictional force between the films at the periphery of the winding core, thereby improving the effectiveness of preventing misalignment during transportation and sticking during long-term storage. Furthermore, even if more air escapes from the outer portion of the roll, the thickness of the void layer is kept small throughout the entire film roll, and a uniform void layer is formed between the films.

[0049] Examples of such means include means for changing the film touch pressure by a touch roller, and means for changing the winding tension, winding speed, roller firing angle, etc. The touch roller may be provided in plural numbers, and the surface may be coated with chrome. Te It may be included. The touch roller may be an elastic roller or the like.

[0050] (1.2.2) Calculation method for the thickness of the air gap layer FIG. 3 is a schematic diagram showing the positional relationship between the side surface of the film roll in the width direction and the imaging device. As shown in FIG. 3, the imaging device (E) is installed on the side of the width direction of the film roll (30) wound around the core (R). In FIG. 3, TD is the width direction of the film roll.

[0051] An example of a method for capturing an image of the side surface in the width direction of the film roll using the imaging device and a method for calculating the thickness of the void layer will be described below.

[0052] An imaging unit (U), which is part of the imaging device, photographs the widthwise side of the film roll, centered on an arbitrary point (P) on the widthwise side of the film roll, and obtains image data for calculating the gap between the films.

[0053] FIG. 4 is a schematic diagram of a side surface in the width direction of a film roll as viewed from a plane perpendicular to the side surface.

[0054] Here, when the winding diameter from the core surface (S0) to the outermost film layer (S4) of the film roll is expressed as a percentage as shown in Figure 4, the winding diameter at the core surface (S0) is 0%, and the winding diameter at the outermost film layer (S4) of the film roll is 100%.

[0055] When photographing the area around the core, take a photo at a position that is 20% of the winding diameter (P 20 The side surface is photographed with the center of the image at the center of the lateral surface, and the image data is acquired.

[0056] When photographing the center of the winding, the position where the winding diameter is 50% (P 50 ) and photograph the side of the roll, and when photographing the outer periphery of the roll, the roll diameter is 80%. Ru Place(P 80 The side surface is photographed with the center of the image at the center of the lateral surface, and the image data is acquired.

[0057] The acquired image data is then subjected to edge enhancement processing to obtain a processed image for calculating the thickness of the void layer as shown in Figure 5, and the thickness of the void layer between adjacent films at each of the periphery of the core, the center of the winding, and the outer periphery of the winding on the side of the film roll in the width direction is calculated.

[0058] The thickness of the void layer between films is calculated in three regions: the periphery of the winding core, the center of the winding, and the outer periphery of the winding. Therefore, before providing specific examples for calculating the thickness of the void layer, we will first explain the concepts of the three regions: the periphery of the winding core, the center of the winding, and the outer periphery of the winding.

[0059] FIG. 6 is a simplified conceptual diagram of a part of the side surface in the width direction of the film roll, for illustrating the peripheral part of the winding core, the central part of the winding, and the outer peripheral part of the winding.

[0060] In Figure 6, the layer of film wound directly around the winding core (R) and attached to the winding core surface (S0) (not shown) is designated as S1, and the outermost layer of the film roll is designated as S4. When the area from S1 to S4 is divided into three equal areas, the area on the winding core side is designated as the winding core peripheral area (A), the area on the outside of the winding is designated as the winding outer peripheral area (C), and the area between the winding core peripheral area (A) and the winding outer peripheral area (C) is designated as the winding center area (B). In addition, the film layer forming the boundary between the peripheral portion (A) of the winding core and the central portion (B) of the winding is designated as S2, and the film layer forming the boundary between the central portion (B) of the winding and the outer peripheral portion (C) of the winding is designated as S3.

[0061] As a specific example for calculating the thickness of the void layer in the peripheral portion of the winding, for example, the following calculation method can be mentioned.

[0062] (Example of how to calculate the thickness of the air gap layer) For example, when calculating the thickness of the void layer around the core, 20 The side of the film roll in the width direction is photographed with the center (P ) and image data for calculating the gap between the films is obtained. After that, edge enhancement processing is performed on the obtained image data to obtain a processed image as shown in Figure 5. 20 The radial length is measured starting from the point at which the film is wound, and ending at the point at the 100th layer perpendicular to the film surface, and the thickness of the void layer X [μm] is calculated using the following formula (A).

[0063] Formula (A) Thickness of void layer X [μm] = [radial length [μm] - (average thickness per film layer measured with a film thickness meter [μm]) × (number of layers)] ÷ (number of layers)

[0064] In the above formula, the (number of layers) is determined by the layer number at which the end point is located, perpendicular to the film surface and toward the outside of the winding. If the end point is located at the 100th layer as mentioned above, the (number of layers) = 100.

[0065] In calculating the thickness of the void layer at the center of the winding, the thickness at the aforementioned position (P 20 ) to the position (P 50 ), the thickness of the void layer at the outer periphery of the winding is calculated in the same manner as above, except that the thickness is changed to the position (P 20 ) to the position (P 80 ) is calculated in the same manner as above, except that

[0066] When the overall length of the film roll is short and the side surface of the film roll in the width direction is photographed with the aforementioned arbitrary point (P) as the center, if there are fewer than 100 layers perpendicular to the film surface toward the outside of the winding, for example, if there are only up to 70 layers, the radial length can be measured with the point at the 70th layer as the end point, and the thickness X [μm] of the void layer can be calculated using the above formula (A).

[0067] As the film thickness meter in the above formula (A), for example, an in-line retardation / film thickness measuring device RE-200L2T-Rth+film thickness (manufactured by Otsuka Electronics Co., Ltd.) can be used.

[0068] (System configuration of imaging unit and imaging device) The imaging unit used had the following configuration: Figure 7 is a schematic diagram of the internal structure of the imaging unit (U), and S in Figure 7 is the surface to be measured (side surface in the width direction) of the film roll. The main components in Figure 7 are as follows:

[0069] <Component parts> Total reflection mirror (60) Half mirror(61) Telecentric lens (62) (MML1-HR130VI-35F: Moritex Corporation, magnification x1, WD 130mm) High-brightness line lighting (63) (LNSP2-100SW: CCS Corporation) Monochrome line sensor camera (64) (RMSL8K39CL: manufactured by Nippon Electro Devices Co., Ltd., 8000 pixels at 3.5 μm / pixel)

[0070] The system configuration of the imaging device is as shown in the schematic diagram of FIG.

[0071] 2. Film roll manufacturing method The method for producing a film roll of the present invention is a method for producing a film roll that does not have a knurled portion, and is characterized in that, when the thickness of the gap layer between adjacent films in the peripheral portion of the winding core, measured at the side portion in the width direction of the film roll, is X [μm] and the thickness of the gap layer between adjacent films in the outer peripheral portion of the winding is Y [μm], X and Y are adjusted to satisfy the relationship of formula (1).

[0072] In the above-mentioned method for producing a film roll, it is preferable to adjust X [μm] and Y [μm] so as to satisfy the formula (2) and the formula (3), from the viewpoint of preventing misalignment during transportation and preventing sticking during long-term storage.

[0073] Furthermore, it is preferable to adjust the film touch pressure around the core within a range of 6 to 55 [N / m], the film touch pressure around the center of the winding within a range of 4 to 40 [N / m], and the film touch pressure around the outer periphery of the winding within a range of 3 to 30 [N / m], from the viewpoint of preventing misalignment during transport and preventing sticking during long-term storage.

[0074] For producing the film roll of the present invention, a conventional production method such as an inflation method, a T-die method, a calendar method, a cutting method, a casting method, an emulsion method, or a hot press method can be used. From the viewpoints of suppressing coloration, foreign matter defects, and optical defects such as die lines, the solution casting method and the melt casting method are preferred, and the solution casting method is particularly preferred for achieving a uniform film surface.

[0075] (2.1) Solution casting method FIG. 9 is a flow chart showing the flow of the manufacturing process by the solution casting film-forming method, and FIG. 10 is a schematic diagram of an apparatus for manufacturing a film by the solution casting film-forming method.

[0076] The solution casting film-forming method will be described below with reference to FIGS. The film manufacturing method using the solution casting film-forming method includes a dope preparation process (S1), a casting process (S2), a peeling process (S3), a shrinking process (S4), a first drying process (S5), a first stretching process (S6), a first cutting process (S7), a second stretching process (S8), a second cutting process (S9), a second drying process (S10), a third cutting process (S11), and a winding process (S12).

[0077] It should be noted that the above manufacturing method does not necessarily include both the first drying step [S5] and the second drying step [S10], and it is sufficient to include at least one of these steps. In addition, it is sufficient that the method includes any one of the first stretching step [S6], the second stretching step [S8], the first cutting step [S7], the second cutting step [S9], and the third cutting step [S11].

[0078] (2.1.1) Dope preparation (stirring and preparation) step [S1] Hereinafter, as one embodiment of the present invention, a dope preparation process will be described using a cycloolefin resin (hereinafter also referred to as "COP") as a thermoplastic resin as an example, but the present invention is not limited thereto.

[0079] In the dope preparation (stirring preparation) step [S1] of FIG. 9, at least a resin and a solvent are stirred in the stirring tank (1a) of the stirring device (1) of FIG. 10 to prepare a dope to be cast onto the support (3) (endless belt).

[0080] (solvent) As the solvent, a mixed solvent of a good solvent and a poor solvent is used. This process is a process in which the COP and, if necessary, other compounds are dissolved in a solvent mainly consisting of a good solvent for the COP in a dissolution vessel while stirring to form a dope, or a process in which the COP solution is mixed with, if necessary, other compound solutions to form a dope, which is a main solution.

[0081] From the viewpoint of reducing the drying load after casting the dope onto the support, it is preferable that the concentration of COP in the dope is high. However, if the concentration is too high, the load during filtration of the dope increases, resulting in poor accuracy. Therefore, it is necessary to achieve both the reduction of the drying load and the suppression of the load during filtration. In order to achieve both of these, the concentration of COP in the dope is preferably in the range of 10 to 35% by mass, more preferably in the range of 15 to 30% by mass. The dope preferably contains water in the range of 0.01 to 2% by mass.

[0082] The solvents used in the dope may be used alone or in combination of two or more kinds. However, it is preferable to use a mixture of a good solvent and a poor solvent for COP in terms of production efficiency, and it is preferable to use a larger amount of the good solvent in terms of solubility of COP.

[0083] The preferred range of the mixing ratio of the good solvent to the poor solvent is 70 to 98 mass % of the good solvent and 2 to 30 mass % of the poor solvent.

[0084] In this specification, a "good solvent" for COP is defined as a solvent that dissolves the COP alone, and a "poor solvent" for COP is defined as a solvent that swells or does not dissolve the COP alone. Therefore, the solvent may be a good solvent or a poor solvent depending on the average degree of substitution of the COP.

[0085] The good solvent used in the present invention is not particularly limited, but examples thereof include organic halogen compounds such as methylene chloride, dioxolanes, acetone, methyl acetate, and methyl acetoacetate, and particularly preferred are methylene chloride and methyl acetate. but Examples include:

[0086] The poor solvent used in the present invention is not particularly limited, but for example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone, etc. are preferably used.

[0087] Furthermore, the solvent used to dissolve the COP is removed from the film by drying in each step and recovered, and then reused.

[0088] The recovered solvent may contain trace amounts of additives added to the COP, such as plasticizers, ultraviolet absorbers, resins, and monomer components. However, even if these additives are contained, the recovered solvent can be preferably reused, and if necessary, can be purified and reused.

[0089] (Dissolution method) As the method for dissolving COP when preparing the dope described above, a general method can be used. Specifically, preferred are methods carried out at normal pressure, at or below the boiling point of the main solvent, and methods carried out under pressure at or above the boiling point of the main solvent. Combining heating and pressure allows heating above the boiling point at normal pressure.

[0090] In addition, a method of stirring and dissolving while heating at a temperature above the boiling point of the solvent at normal pressure but within a range in which the solvent does not boil under pressure is also preferred, as this prevents the formation of lumpy undissolved matter called gel or lumps.

[0091] Also preferably used is a method in which the COP is mixed with a poor solvent to wet or swell it, and then a good solvent is added to dissolve it.

[0092] The pressure may be applied by injecting an inert gas such as nitrogen gas or by increasing the vapor pressure of the solvent by heating. Heating is preferably performed from the outside, and for example, a jacket type is preferred because it is easy to control the temperature.

[0093] A higher heating temperature after adding a solvent is preferable from the viewpoint of solubility of COP, but if the heating temperature is too high, the required pressure increases, resulting in poor productivity.

[0094] The heating temperature is preferably within a range of 30 to 120°C, more preferably within a range of 60 to 110°C, and even more preferably within a range of 70 to 105°C. The pressure is also adjusted so that the solvent does not boil at the set temperature.

[0095] Alternatively, a cooling dissolution method is also preferably used, by which COP can be dissolved in a solvent such as methyl acetate.

[0096] (filtration) Next, it is preferable to filter this COP solution (dope during or after dissolution) using a suitable filter material such as filter paper.

[0097] It is preferable that the filter has a low absolute filtration accuracy in order to remove insoluble matters, but if the absolute filtration accuracy is too low, there is a problem that the filter is prone to clogging. Therefore, a filter medium with an absolute filtration accuracy of 0.008 mm or less is preferred, a filter medium with an absolute filtration accuracy in the range of 0.001 to 0.008 mm is more preferred, and a filter medium with an absolute filtration accuracy in the range of 0.003 to 0.006 mm is even more preferred.

[0098] There are no particular restrictions on the material of the filter medium, and ordinary filter medium can be used, but filter medium made of plastic such as polypropylene or Teflon (registered trademark), or filter medium made of metal such as stainless steel is preferred as it does not cause fiber shedding.

[0099] It is preferable to remove or reduce impurities, particularly bright spot foreign matter, contained in the raw COP by filtration.

[0100] Bright spot foreign matter is a point (foreign matter) that is visible as light leaking from the opposite side when two polarizing plates are placed in a cross-Nicol state, a film or the like is placed between them, and light is shone from one polarizing plate side and observed from the other polarizing plate side. The number of bright spots is 200 / cm and is 0.01 mm or more in diameter. 2 It is preferable that: More preferably 100 / cm 2 More preferably, it is 50 pieces / m or less. 2 or less, and more preferably 0 to 10 particles / cm 2 The following is the result. It is also preferable to have fewer bright spots of 0.01 mm or less.

[0101] The dope can be filtered by a conventional method. However, a method of filtering the dope while heating the solvent at a temperature above the boiling point of the solvent at normal pressure and within a range where the solvent does not boil under pressure is preferred because the increase in the difference in filtration pressure (referred to as differential pressure) before and after filtration is small.

[0102] The temperature is preferably in the range of 30 to 120°C, more preferably in the range of 45 to 70°C, and even more preferably in the range of 45 to 55°C.

[0103] A small filtration pressure is preferred. Specifically, it is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, and even more preferably 1.0 MPa or less.

[0104] (2.1.2) Casting process [S2] In the casting step S2 shown in Fig. 9, the dope prepared in the dope preparation step S1 is sent to the casting die (2) shown in Fig. 10 through a conduit via a pressure type metering gear pump or the like, and the dope is cast from the casting die (2) at a casting position on the support (3) made of a stainless steel endless belt that is rotated and moves endlessly, to form a casting film (5).

[0105] In this case, the inclination of the casting die (2), i.e., the direction of the dope being discharged from the casting die (2) to the support (3), may be appropriately set so that the angle with respect to the normal to the surface of the support (3) (the surface onto which the dope is cast) falls within the range of 0 to 90°.

[0106] Thereafter, the casting film (5) is heated and dried on the support (3) to evaporate the solvent until the casting film (5) can be peeled off from the support (3) by a peeling roller (4). In the present invention, the casting film refers to the dope film cast from the lip portion.

[0107] The evaporation is preferably carried out in an atmosphere within a range of 5 to 75°C. The solvent can be evaporated by applying hot air to the upper surface of the casting film (5) and / or by transferring heat from the back surface of the support (3) using a liquid, or by transferring heat from the front and back by radiant heat. The method of transferring heat from the front and back by radiant heat is preferred because of its high drying efficiency. A combination of these methods is also preferably used.

[0108] The casting width is preferably 1.3 m or more from the viewpoint of productivity. More preferably, it is in the range of 1.3 to 4.0 m. If the casting width does not exceed 4.0 m, no streaks will appear during the manufacturing process and the film will be more stable during the subsequent transport process. From the viewpoint of transportability and productivity, a range of 1.3 to 3.0 m is more preferable.

[0109] (Casting die) Casting dies include coat hanger dies and T-dies, and any of these is preferably used.

[0110] In order for those skilled in the art to improve the uniformity of the film thickness in the casting process, a method for controlling the slit gap (the tip opening of the liquid outlet of the slit nozzle) at the lip part of the casting die (the part of the casting die slit from which the dope comes out) can be mentioned in both the solution casting film-forming method and the melt casting film-forming method.

[0111] For example, when extruding a highly viscous dope (including melt), the width of the slit gap varies. To prevent this, multiple heat bolts are installed in the width direction to control the slit gap.

[0112] However, this method has the problem that there is a physical limit to the number of heat bolts that can be installed. In order to suppress the pressure fluctuation in the width direction, which causes the variation in the width direction of the slit gap, there is a method of changing the internal structure of the casting die in the width direction. However, this method requires changing the casting die for each product type, which is time-consuming and costly.

[0113] The casting die is provided with a mechanism for adjusting the width of a slit through which the dope is discharged (or the resin is extruded in the case of melting). It is preferable to adjust the width of the slit through which the dope is discharged by the heat bolt of the casting die so that the thickness deviation immediately after discharge is within the range of 1.0 to 5.0% for the entire casting film, thereby controlling the initial film thickness of the casting film.

[0114] In order to increase the film-forming speed of the present invention, two or more of the above-mentioned casting dies may be provided on the support, and the dope may be divided and layered. Alternatively, it is also preferable to obtain a film roll having a laminated structure by a co-casting method in which a plurality of dopes are simultaneously cast. To increase the film-forming speed, two or more casting dies may be provided on the support, and the dope may be divided and layered.

[0115] (Support) The support (3) is preferably a stainless steel belt or a cast drum with a plated surface, and is held by a pair of rollers (3a) and (3b) and a plurality of rollers positioned between them. In this case, the surface of the support is preferably a mirror surface.

[0116] One or both of the rollers (3a) and (3b) are provided with a drive device that applies tension to the support (3), so that the support (3) is used in a tensioned state.

[0117] The surface temperature of the support (3) in the casting step (S2) is in the range of -50°C to the boiling point of the solvent, and a higher temperature is preferred since it increases the drying speed of the cast film.

[0118] The support temperature is preferably in the range of 0 to 55°C, more preferably in the range of 22 to 50°C.

[0119] The temperature of the support may be the same throughout or may vary depending on the position.

[0120] The method for controlling the temperature of the support (3) is not particularly limited, but includes a method of blowing hot or cold air onto the support, and a method of bringing hot water into contact with the back side of the support. The use of warm water is preferable because heat is transferred more efficiently and the time required for the temperature of the support to become constant is shorter. When using hot air, the temperature of the air used may be higher than the desired temperature.

[0121] (2.1.3) Peeling process [S3] In this process, in the casting step [S2], the solvent is evaporated on the support (3) until the cast film (5) has a film strength that allows peeling, and the film is dried and solidified or cooled and solidified, and then the film is peeled off from the support (3) before it makes a full revolution around the support (3). That is, this step is a step of peeling off the film from which the solvent has evaporated on the support (3) at the peeling position. At this time, from the viewpoints of surface quality, moisture permeability, and releasability, it is preferable to peel the film from the support within a range of 30 to 600 seconds.

[0122] In the peeling step [S3], the film is peeled off by a peeling roller (4) (a roll that helps peel off the film) while maintaining its self-supporting properties. The temperature at the peeling position on the support is preferably within the range of -50 to 40°C, more preferably within the range of 10 to 40°C, and most preferably within the range of 15 to 30°C.

[0123] (Residual solvent amount) The amount of residual solvent in the film on the support (3) during peeling in the peeling step [S3] is adjusted appropriately depending on the strength of the drying conditions, the length of the support (3), etc., and the amount of residual solvent in the shrinking step [S4] is greatly influenced by the thickness of the film, the resin, etc., so there is an overlapping range of the preferred ranges of residual solvent amount in the peeling step [S3] and the shrinking step [S4].

[0124] The amount of residual solvent in a film varies depending on the thickness of the film, but if there is too much residual solvent at the peeling point (the point where the film is peeled from the support), the film may become too soft and difficult to peel, which may impair flatness and make it more susceptible to horizontal steps, wrinkles, and vertical streaks due to the peeling tension. Conversely, if the amount of residual solvent is too small, part of the film may peel off during the process.

[0125] From the above viewpoint, in order for the film to exhibit good flatness, it is desirable that the amount of residual solvent is within the range of 10 to 50% by mass in terms of the balance between economic speed and quality.

[0126] As a method for increasing the film production speed (the film production speed can be increased because the film is peeled off while the amount of residual solvent is still as large as possible), there is a gel casting method, which allows peeling even when the amount of residual solvent is large.

[0127] The above-mentioned methods include a method in which a poor solvent for COP is added to the dope, and the dope is cast and then the cast film is gelled; a method in which the support is cooled to gel the cast film and then the film is peeled off in a state containing a large amount of residual solvent. There is also a method of adding a metal salt to the dope.

[0128] As described above, by gelling the cast film on the support to strengthen the film, the film can be peeled off from the support more quickly, thereby increasing the film production rate.

[0129] The residual solvent amount is defined by the following formula:

[0130] Formula: Residual solvent amount [mass%] = {(MN) / N} x 100

[0131] In the above formula, M is the mass of a sample taken at any time during or after the production of the cast membrane or film, and N is the mass of M after heating at 115° C. for 1 hour.

[0132] (peel tension) The peel tension when peeling the film from the support is preferably 300 N / m or less. A more preferable range is 196 to 245 N / m, but if wrinkles are likely to occur during peeling, peeling is preferably performed with a tension of 190 N / m or less.

[0133] (2.1.4) Shrinkage process [S4] The shrinking step [S4] is a step of shrinking the film (F) in the width direction within the plane. The film (F) can be shrunk, for example, by treating the film at a high temperature without holding the film widthwise to increase its density, by applying tension to the film after peeling it from the support in the machine direction (hereinafter also referred to as "MD direction"), and by stretching and shrinking the film in the width direction (TD direction) perpendicular to the MD direction within the film plane, or by rapidly reducing the amount of residual solvent in the film. In this case, the film shrinks in the transverse direction (hereinafter also referred to as "TD direction"), which is perpendicular to the MD direction within the film plane.

[0134] The shrinkage process promotes entanglement between resin molecules (matrix molecules) in the thickness direction of the film, so that, for example, when manufacturing a polarizing plate, even if the film is bonded to a polarizer via an adhesive, the adhesive is more likely to penetrate into the film through the entangled parts (crosslinked parts) between the matrix molecules. As a result, the film can be firmly fixed to the polarizer via the adhesive, and the peel strength of the film from the polarizer can be improved. That is, good adhesion between the film and the polarizer can be ensured.

[0135] (Definition of shrinkage rate) In the present invention, the shrinkage rate is defined by the following formula.

[0136] Formula: Shrinkage rate [%] = film width at the end of the shrinking process [mm] / film width at the start of the shrinking process [mm] x 100

[0137] Here, in the shrinkage step [S4], if the shrinkage rate of the film is too small, the effect of promoting entanglement between matrix molecules will be insufficient, and if it is too large, there is a concern that the production efficiency of the film (stretched film) will decrease. Therefore, the shrinkage rate of the film in the shrinking step [S4] is preferably within a range of 1 to 40%, and more preferably within a range of 5 to 20%.

[0138] (Methods for measuring and calculating shrinkage rate) The width of the film can be measured using LS-9000 manufactured by Keyence Corporation. The shrinkage rate of the film according to the present invention was determined by measuring the width of the film every second for 5 minutes (300 seconds) using the above-mentioned measuring device, taking the average of the measured values ​​as the width of the film, and substituting it into the above formula. However, the method is not limited to the above, and for example, the width of the film may be determined by reading the value from a ruler, and then substituting it into the above formula.

[0139] (2.1.5) First drying step [S5] In the first drying step [S5], the film (F) is heated on the support by a drying device (6) to evaporate the solvent and dry the film.

[0140] In the drying device (6) in FIG. 10, the film (F) is transported by a plurality of transport rolls arranged in a staggered pattern when viewed from the side, and the film (F) is dried during this transport.

[0141] The drying method in the drying device (6) is not particularly limited, and the film (F) is generally dried using hot air, infrared rays, a heated roll, microwaves, etc., but from the standpoint of simplicity, a method of drying the film (F) with hot air is preferred. A combination of these methods is also preferred. The first drying step [S5] may be carried out as needed.

[0142] If the film is not too thick, it will dry quickly, but drying too quickly can easily damage the flatness of the finished film. When drying a film at high temperatures, it is necessary to consider the amount of residual solvent before drying. However, if the amount of residual solvent is not too large, it is possible to prevent breakdown due to solvent foaming.

[0143] The amount of residual solvent before the first drying step [S5] is preferably about 30% by mass or less, and the drying temperature is generally within the range of 30 to 250°C throughout the entire drying step. It is particularly preferable to dry within the range of 35 to 200°C, and it is preferable to increase the drying temperature stepwise.

[0144] Film drying is generally achieved by either the roll drying method (a method in which the film is dried by passing it alternately through multiple rolls arranged above and below) or the tenter method, in which the film is dried while being transported.

[0145] When a tenter stretching apparatus is used to dry the film, it is preferable to use an apparatus that can independently control the gripping length (the distance from the start of gripping to the end of gripping) of the film on the left and right sides using the left and right gripping means of the tenter stretching apparatus in the stretching step described below. It is also preferable to intentionally create zones with different temperatures in the stretching process to improve flatness.

[0146] Furthermore, it is also preferable to provide a neutral zone between the different temperature sections so that each section does not interfere with the other.

[0147] (2.1.6) First stretching process [S6] The first stretching step [S6] may be a step of stretching the film (F) only in the MD direction within the film plane, or a step of stretching only in the TD direction, or in both the MD and TD directions, or a step of stretching in an oblique direction. There is no limitation on the stretching direction, but from the viewpoint of obtaining a wide film, it is preferable to include a step including stretching at least in the width direction. Such stretching is carried out by a stretching device (7).

[0148] (Stretching method) Examples of stretching methods include a method in which a difference in peripheral speed between rolls is used to stretch in the transport direction (longitudinal direction of the film; film-forming direction; casting direction; machine direction; MD direction) (longitudinal stretching), a method in which both side edges of the film (F) are fixed with clips or the like to stretch in the width direction (directions perpendicular to the film plane; width direction of the film; transverse direction; TD direction) (transverse stretching), a method in which longitudinal stretching and transverse stretching are performed in sequence (sequential biaxial stretching), and a method in which longitudinal stretching and transverse stretching are performed simultaneously (simultaneous biaxial stretching).Of these, a tenter stretching device is used for transverse stretching and simultaneous biaxial stretching (including diagonal stretching). A tenter stretching device is a device that stretches a film by gripping both widthwise ends of the film with clips and expanding the gap between the clips while running together with the film.

[0149] Among the above methods, the so-called tenter method using a tenter stretching device is preferred for improving film performance, productivity, flatness and dimensional stability.

[0150] In the case of the so-called tenter method, it is preferable to drive the clip portion by a linear drive system, since this allows smooth stretching and reduces the risk of breakage.

[0151] The width holding or transverse stretching in the film-forming process is preferably carried out by a tenter stretching device, which may be a pin tenter or a clip tenter. In addition to stretching, drying may also be carried out in the stretching device (7).

[0152] (Stretching ratio) In order to ensure a high retardation, a wide width, and to promote penetration of an adhesive when adhering to a polarizer, it is preferable to stretch the film at a high magnification in the stretching step. However, if the stretching ratio is too high, crazes may occur in the film due to the stretching stress, or the entanglement between matrix molecules that maintain the strength of the film may be dissociated, resulting in weakening of the film.

[0153] Therefore, the stretching ratio in the stretching step is preferably within the range of 1.1 to 5.0 times, and more preferably within the range of 1.3 to 3.0 times.

[0154] In the present invention, the term "stretching ratio" refers to the ratio [%] of the area of ​​the film after stretching to the area of ​​the film before stretching. That is, the above-mentioned stretching engineering The "stretching ratio" in this step is preferably a total area ratio of 1.1 to 5.0 times, more preferably 1.3 to 3.0 times, resulting from stretching in the longitudinal (length) and transverse (width) directions of the film.

[0155] When the stretching is carried out multiple times, it is preferable that the stretching at the highest magnification, which poses the highest risk of dissociation of the matrix molecules, is carried out in the final stretch. For example, in FIG. 9, the highest stretching ratio is preferably performed in the second stretching step. In this case, the entanglement of the matrix molecules can be strengthened before the maximum stretching ratio, so that even when the film is stretched to the maximum stretching ratio, dissociation of the entanglement of the matrix molecules can be suppressed, thereby suppressing cohesive failure.

[0156] (Tenter stretching device) Hereinafter, an example in which a tenter stretching device is used as the stretching device (7) will be described with reference to FIGS.

[0157] FIG. 11 is a plan view schematically showing the internal configuration of a tenter stretching apparatus, and is a cross-sectional view of the tenter stretching apparatus as viewed from above along a plane perpendicular to the film surface. FIG. 12 shows the tenter stretching apparatus with the cover removed, and the cover is indicated by a two-dot chain line.

[0158] FIG. 13 is a schematic diagram of the nozzles and heaters installed in the three zones of the tenter stretching apparatus as viewed from the front. As shown in Figure 13, the infrared (IR) heater is placed only above the nozzle so that the film will not come into contact with the infrared (IR) heater when the film breaks. However, since the radiant energy from the infrared (IR) heater can be concentrated in a narrower area by placing the infrared (IR) heater closer to the film, the infrared (IR) heater is placed as close to the film as possible without interfering with the width adjustment operation of the clips.

[0159] In addition, in FIG. 13, heat treatment from the central nozzle (105) is mainly shown, and heat treatment from the end nozzle (104) is not performed in this example, but it is possible to use both in this embodiment.

[0160] When performing heat treatment, it is better to have an infrared (IR) heater coming out of the nozzle gap as shown in Figure 14, as this will allow radiant energy to be transmitted to the film without waste.

[0161] As shown in Figure 11, infrared (IR) heaters were arranged in a row so that the entire width of the film could be heated even before stretching. The heaters may be arranged in a staggered pattern in the longitudinal direction.

[0162] The tenter stretching device (40) is provided with a large number of clips (42) for gripping both ends of the film (F) in the width direction, and the clips (42) are attached to an endless chain (48) at regular intervals. The endless chains (48) are arranged on both sides of the film (F), and are respectively stretched between a driving sprocket (50) on the inlet side and a driven sprocket (52) on the outlet side. The driving sprocket (50) is connected to a motor (not shown), and the driving sprocket (50) is rotated by driving the motor. As a result, the endless chain (48) travels around between the driving sprocket (50) and the driven sprocket (52), causing the clips (42) attached to the endless chain (48) to travel around.

[0163] A rail (54) for guiding the endless chain (48) (or clip (42)) is provided between the driving sprocket (50) and the driven sprocket (52). The rails (54) are arranged on both sides of the film (F), and the distance between the rails (54) is configured to be wider on the downstream side than on the upstream side in the transport direction of the film (F). As a result, when the clips (42) travel around, the distance between the clips (42) is increased, so that the film (F) held by the clips (42) can be stretched laterally in the width direction.

[0164] The driving sprocket (50) and the driven sprocket (52) each have a release member (56) attached thereto. The opening member (56) is a device that displaces a flapper (not shown) of the clip (42), which will be described later, from a gripping position to an open position, and this opening member (56) automatically performs the gripping and opening operations of the film (F).

[0165] As shown in FIGS. 11, 12 and 14, the tenter stretching device (40) is provided with a preheating zone, a (transverse) stretching zone and a heat setting zone inside. The zones are separated from each other by windshield curtains (not shown). In each zone, hot air is supplied to the film (F) from above, below, or both.

[0166] The hot air is blown out uniformly across the width of the film (F) while being controlled at a predetermined temperature for each zone. This allows the interior of each zone to be controlled to a desired temperature. Each zone will now be described.

[0167] The preheating zone is a zone where the film (F) is preheated, and the film (F) is heated without widening the gap between the clips (42).

[0168] The film (F) preheated in the preheating zone moves to the (transverse) stretching zone. The (transverse) stretching zone is a zone in which the film (F) is (transversely) stretched in the width direction by increasing the distance between the clips (42). The stretching ratio in this (transverse) stretching treatment is preferably in the range of 1.0 to 2.5 times, more preferably in the range of 1.05 to 2.3 times, and even more preferably in the range of 1.1 to 2 times.

[0169] The film (F) stretched laterally in the transverse stretching zone moves to the heat setting zone.

[0170] In the present embodiment, the interior of the tenter stretching apparatus (40) is divided into a preheating zone, a (transverse) stretching zone, and a heat setting zone, but the types and arrangement of the zones are not limited to these. For example, a cooling zone for cooling the film (F) may be provided after the (transverse) stretching zone. A heat relaxation zone may also be provided within the heat setting zone.

[0171] In this embodiment, only (transverse) stretching is performed in the tenter stretching device (40), but stretching in the machine direction may also be performed simultaneously. In this case, the pitch of the clips (42) (the distance between the clips (42) in the conveying direction) may be changed when the clips (42) are moved. The mechanism for changing the pitch of the clip (42) may be, for example, a pantograph mechanism or a linear guide mechanism.

[0172] (Heat treatment timing) A tenter stretching apparatus is usually divided into multiple zones, such as a preheating zone for heating the film, a transverse stretching zone for stretching the film in the transverse direction, a heat setting zone for crystallizing the film, and a relaxation zone for removing thermal stress from the film, as shown in Figures 11, 12, and 14.

[0173] (Furnace temperature) Generally, the temperature inside the furnace is preferably in the range of 120 to 200°C, more preferably in the range of 120 to 180°C. Here, the "oven temperature" refers to the temperature (H A = 100 mm), and is defined as the average value of each temperature measured every minute for one hour.

[0174] Generally, the temperature inside the furnace is preferably in the range of 120 to 200°C, more preferably in the range of 120 to 180°C. Here, when a temperature gradient is applied longitudinally in a plurality of compartments, the compartment to be heat-treated is the subject of the term.

[0175] Furthermore, the furnace temperature differs depending on whether or not heat treatment is performed in the stretching zone. However, when heat treatment is performed in the stretching zone, the furnace temperature refers to the furnace temperature in the stretching zone before heat treatment is performed.

[0176] (Residual solvent amount) The amount of residual solvent in the film during stretching is preferably 20% by mass or less, and more preferably 15% by mass or less.

[0177] (2.1.7) First cutting process [S7] In the first cutting step [S7], a cutting section (8) consisting of a slitter cuts both widthwise ends of the film (F) stretched in the first stretching step [S6]. In the film (F), the portions remaining after cutting both ends constitute the product portion that will become the film product. On the other hand, the portion cut from the film (F) may be recovered and reused as part of the raw material for film production.

[0178] (2.1.8) Second stretching process [S8] In the second stretching step (S8), the film (F) is stretched by the stretching device (9) in the same manner as in the first stretching step (S6). As the stretching method in this case, a stretching method in which a difference in peripheral speed between rolls is used to stretch in the conveying direction (MD direction), or a tenter method in which both side edges of the film (F) are fixed with clips or the like and stretched in the width direction (TD direction) is preferred in order to improve the performance, productivity, flatness and dimensional stability of the film. In addition to stretching, drying may also be carried out in the stretching device (9).

[0179] (2.1.9) Second cutting process [S9] In the second cutting step (S9), a cutting unit (10) made of a slitter cuts both ends in the width direction of the formed film (F) in the same manner as in the first cutting step (S7). The clipped portions at both ends of the film are usually cut off because the film is deformed and cannot be used as a product. If the material is not degraded by heat, it can be recovered and reused.

[0180] In the film (F), the portions remaining after cutting both ends constitute the product portion that will become the film product. On the other hand, the portion cut from the film (F) is recovered and reused as part of the raw material for film production.

[0181] (2.1.10) Second drying process [S10] In the second drying step (S10), the film (F) is dried in a drying device (11) in the same manner as in the first drying step (S5). In the drying device (11), the film (F) is transported by a plurality of transport rolls arranged in a staggered pattern when viewed from the side, and the film (F) is dried during this transport.

[0182] The drying method in the drying device (6) is not particularly limited, and generally includes hot air, infrared rays, a heated roll, microwaves, and the like. Among the above drying methods, the method of drying the film (F) with hot air is preferred from the viewpoint of simplicity. The second drying step [S10] may be carried out as needed.

[0183] (2.1.11) Third cutting process [S11] In the third cutting step [S11], similar to the first cutting step [S7] and the second cutting step [S9], a cutting section (12) consisting of a slitter cuts both ends of the formed film (F) in the width direction. In the film (F), the portions remaining after cutting both ends constitute the product portion that will become the film product. On the other hand, the portion cut from the film (F) is recovered and reused as part of the raw material for film production.

[0184] (2.1.12) Winding process [S12] Finally, in the winding step (S12), the film (F) is wound by a winding device (13) to obtain a film roll. That is, in the winding step, the film (F) is wound around a core while being transported, thereby producing a film roll. The initial tension when winding the film in the winding step is preferably in the range of 20 to 300 N / m.

[0185] FIG. 15 is a schematic diagram showing the process of winding a film and a cross section of the film roll of the present invention after winding. When winding the film (F), it is preferable to provide a touch roller (33) as shown in FIG. 15, and to appropriately change the film touch pressure to form a desired void layer. In FIG. 15, the formed film (31) is wound around a roller (32) and a touch roller (33) and taken up as a film roll (30).

[0186] (Residual solvent amount) More specifically, after the residual solvent content in the film becomes 2% by mass or less, the film is wound on a winding device (1 3) is a process of winding up the film, and by keeping the residual solvent content at 0.4% by mass or less, a film with good dimensional stability can be obtained. In particular, it is preferable to wind the film when the amount of residual solvent is in the range of 0.00 to 0.20% by mass.

[0187] (Winding method) The film (F) can be wound using a commonly used winder, and there are various tension control methods such as the constant torque method, constant tension method, taper tension method, and program tension control method with constant internal stress, and any of these can be used appropriately.

[0188] Before winding, the ends are slit and cut to the width of the product, and both ends of the film may be subjected to a surface modification treatment to prevent sticking or scratches during winding.

[0189] (After winding) The film roll of the present invention is preferably a long film, specifically within the range of about 100 to 10,000 m, and is usually provided in a roll form.

[0190] (2.2) Film roll manufacturing process using the melt casting method The film according to the present invention can also be produced by a melt casting film production method. The "melt film-forming method" refers to a method in which a composition containing a thermoplastic resin and the above-mentioned additives is heated to a temperature at which it exhibits fluidity and melted, and then the melt containing the fluid thermoplastic resin is cast.

[0191] Molding methods involving heating and melting can be specifically classified into melt extrusion molding, press molding, inflation molding, injection molding, blow molding, stretch molding, and the like. Among these molding methods, the melt extrusion method is preferred from the viewpoints of mechanical strength and surface precision.

[0192] FIG. 16 is a flowchart showing the flow of the manufacturing process of the melt-casting film-forming method. FIG. 17 is a schematic diagram of an apparatus for producing a film by the melt-casting film-forming method. The solution casting film-forming method will be described below with reference to FIGS.

[0193] The method for producing a film roll using the melt-casting film-forming method includes an extrusion process (M1), a casting / molding process (M2), a first stretching process (M3), a first cutting process (M4), a second stretching process (M5), a second cutting process (M6), and a winding process (M7).

[0194] It should be noted that the above-mentioned production method does not necessarily include both the first stretching step [M3] and the second stretching step [M5], and it is sufficient to include at least one of these steps. Similarly, the first cutting step [M4] and the second cutting step [M6] may also include at least one of the steps.

[0195] (2.2.1) Extrusion process [M1] In the extrusion step [M1], at least a resin is melt-extruded in an extruder (14) and molded onto a casting drum (16). The resins that can be used in the present invention will be described in detail below.

[0196] It is also preferable that the resin be kneaded and pelletized in advance. The pelletization may be carried out by a known method.

[0197] For example, dry resin, plasticizer, and other additives are fed into an extruder using a feeder, kneaded using a single-screw or twin-screw extruder, extruded in the form of a strand from a casting die (15), cooled with water or air, and cut into pellets.

[0198] The additives may be mixed with the resin before being fed to the extruder, or the additives and the resin may be fed to the extruder using separate feeders. Furthermore, it is preferable to mix small amounts of additives such as particles and antioxidants into the resin in advance in order to mix them uniformly.

[0199] When the pellets are introduced into the extruder from the supply hopper, it is preferable to prevent oxidative decomposition by drying, under vacuum, reduced pressure or in an inert gas atmosphere.

[0200] It is preferable that the extruder be operated at a temperature as low as possible that allows pelletization and prevents deterioration of the resin (reduction in molecular weight, coloration, gel formation, etc.) by suppressing shearing force.

[0201] For example, in the case of a twin-screw extruder, it is preferable to use deep-groove type screws and rotate them in the same direction. In view of uniformity of kneading, the intermeshing type is preferred. When the resin pellets are melted, it is preferable to filter them using a leaf disc type filter or the like to remove foreign matter.

[0202] The pellets obtained as described above are used to form a film. Of course, it is also possible to feed the raw material resin (powder, etc.) directly to an extruder using a feeder without pelletizing, and to form a film directly from the resin.

[0203] (2.2.2) Casting / forming process [M2] In the casting and molding process [M2], the resin pellets melted in the extrusion process are passed through a pressure-type metering gear pump or the like and cast into a film form from the casting die (15) through a conduit, and then cast from the casting die (15) onto the casting position on the endless cast drum (16) made of stainless steel and rotated to move endlessly. The cast molten resin pellets are then molded on a casting drum (16) to form a cast film (18).

[0204] The inclination of the casting die (15), i.e., the direction of extrusion of the molten resin / pellets from the casting die (15) onto the support (16), may be appropriately set so that the angle relative to the normal to the surface of the cast drum (16) (the surface onto which the molten resin / pellets are cast) falls within the range of 0 to 90°.

[0205] The film (F) may be formed by using a touch roller (16a) or a cooling drum (17) that assists the casting drum (16) either alone or in combination.

[0206] (2.2.3) First stretching process [M3] In the first stretching step [M3], the film (F) is stretched by a stretching device (19). As the stretching method in this case, a stretching method in which the film is stretched in the MD direction by setting a difference in peripheral speed between rolls, or a tenter method in which the film (F) is stretched in the TD direction by fixing both side edges with clips or the like, is preferred in order to improve the performance, productivity, flatness and dimensional stability of the film. In addition to stretching, drying may also be carried out in the stretching device (19).

[0207] The description of the tenter stretching device, the heat treatment timing, the temperature inside the oven, the stretching temperature, the temperature inside the stretching oven, the amount of residual solvent, etc. will be omitted here because they overlap with those in the first stretching step [S6] in the film roll manufacturing process by the solution casting film-forming method.

[0208] (2.2.4) First cutting process [M4] In the first cutting step [M4], a cutting section (20) consisting of a slitter cuts both ends in the width direction of the formed film (F). In the film (F), the portions remaining after cutting both ends constitute the product portion that will become the film product. On the other hand, the portion cut from the film (F) may be recovered and reused as part of the raw material for film production.

[0209] (2.2.5) Second stretching process [M5] In the second stretching step [M5], the film (F) is stretched by the stretching device (21) in the same manner as in the first stretching step [M3]. As the stretching method in this case, a stretching method in which the film is stretched in the MD direction by setting a difference in peripheral speed between rolls, or a tenter method in which the film (F) is stretched in the TD direction by fixing both side edges with clips or the like, is preferred in order to improve the performance, productivity, flatness and dimensional stability of the film. In addition to stretching, drying may also be carried out in the stretching device (21).

[0210] (2.2.6) Second cutting process [M6] In the second cutting step [M6], the cutting unit (22) made of a slitter cuts both ends in the width direction of the formed film (F) in the same manner as in the first cutting step [M4]. In the film (F), the portions remaining after cutting both ends constitute the product portion that will become the film product. On the other hand, the portion cut from the film (F) may be recovered and reused as part of the raw material for film production.

[0211] (2.2.7) Winding process [M7] Finally, in the winding step [M7], the film (F) is wound by a winding device (23) to obtain a film roll. That is, in the winding step [M7], the film (F) is wound around a core while being transported, thereby producing a film roll.

[0212] The film (F) can be wound using a commonly used winder, and there are various tension control methods such as the constant torque method, constant tension method, taper tension method, and program tension control method with constant internal stress, and any of these can be used appropriately.

[0213] 3. Resin that makes up the film (3.1) Thermoplastic resin There are no limitations on the thermoplastic resin material used for the film of the present invention, as long as it can be handled as a film roll after film formation.

[0214] Examples of thermoplastic resins used for polarizing plates include cellulose ester resins such as triacetyl cellulose (TAC), cellulose acetate propionate (CAP), and diacetyl cellulose (DAC); cyclic olefin resins such as cycloolefin resins (hereinafter also referred to as "COP"); polypropylene resins such as polypropylene (PP); acrylic resins such as polymethyl methacrylate (PMMA); and polyester resins such as polyethylene terephthalate (PET).

[0215] However, it is desirable to use COP in terms of ease of control of stretchability and crystallinity, ease of penetration of adhesive, and ability to ensure better adhesion to the polarizer. The film may be subjected to a surface modification treatment after production.

[0216] Furthermore, the effect of the present invention is enhanced in the thin film region. The thickness of the film is preferably in the range of 5 to 80 μm, more preferably in the range of 10 to 65 μm, and even more preferably in the range of 10 to 45 μm.

[0217] If the thickness of the film is 5 μm or more, the rigidity of the film roll is high, and it becomes easy to maintain the roll shape. If the thickness of the film is 80 μm or less, the mass does not increase too much, making it easier to produce a long film roll.

[0218] (3.1.1) Cycloolefin resin The cycloolefin resin contained in the film roll of the present invention is preferably a polymer of a cycloolefin monomer or a copolymer of a cycloolefin monomer and another copolymerizable monomer.

[0219] The cycloolefin monomer is preferably a cycloolefin monomer having a norbornene skeleton, and more preferably a cycloolefin monomer having a structure represented by the following general formula (A-1) or (A-2).

[0220] [ka]

[0221] In general formula (A-1), R 1 ~R 4 each independently represents a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms, or a polar group, and p represents an integer of 0 to 2. 1 ~R 4 Not all of these represent hydrogen atoms at the same time, and R 1 and R 2 does not simultaneously represent a hydrogen atom, and R 3 and R 4 does not simultaneously represent a hydrogen atom.

[0222] In general formula (A-1), R 1 ~R 4 The hydrocarbon group having 1 to 30 carbon atoms represented by the formula (I) is preferably a hydrocarbon group having 1 to 10 carbon atoms, and more preferably a hydrocarbon group having 1 to 5 carbon atoms.

[0223] The hydrocarbon group having 1 to 30 carbon atoms may further have a linking group containing, for example, a halogen atom, an oxygen atom, a nitrogen atom, a sulfur atom, or a silicon atom. Examples of such linking groups include divalent polar groups such as a carbonyl group, an imino group, an ether bond, a silyl ether bond, and a thioether bond. Examples of the hydrocarbon group having 1 to 30 carbon atoms include a methyl group, an ethyl group, a propyl group, and a butyl group.

[0224] In general formula (A-1), R 1 ~R 4 Examples of the polar group represented by the formula include a carboxy group, a hydroxy group, an alkoxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amido group, and a cyano group.

[0225] Among these, a carboxy group, a hydroxy group, an alkoxycarbonyl group, and an aryloxycarbonyl group are preferred, and from the viewpoint of ensuring solubility during solution casting, an alkoxycarbonyl group and an aryloxycarbonyl group are more preferred.

[0226] In general formula (A-1), p is preferably 1 or 2 from the viewpoint of increasing the heat resistance of the film. When p is 1 or 2, the resulting polymer becomes bulky and the glass transition temperature tends to be improved.

[0227] [ka]

[0228] In general formula (A-2), R 5 represents a hydrogen atom, a hydrocarbon group having 1 to 5 carbon atoms, or an alkylsilyl group having an alkyl group having 1 to 5 carbon atoms. 6 represents a carboxy group, a hydroxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amido group, a cyano group, or a halogen atom (a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom). p represents an integer of 0 to 2.

[0229] R in general formula (A-2) 5 preferably represents a hydrocarbon group having 1 to 5 carbon atoms, and more preferably represents a hydrocarbon group having 1 to 3 carbon atoms.

[0230] R in general formula (A-2) 6 preferably represents a carboxy group, a hydroxy group, an alkoxycarbonyl group or an aryloxycarbonyl group, and more preferably an alkoxycarbonyl group or an aryloxycarbonyl group from the viewpoint of ensuring solubility during solution casting.

[0231] In general formula (A-2), p preferably represents 1 or 2 from the viewpoint of improving the heat resistance of the film. When p is 1 or 2, the resulting polymer becomes bulky and the glass transition temperature tends to be improved.

[0232] A cycloolefin monomer having a structure represented by general formula (A-2) is preferred from the viewpoint of improving solubility in organic solvents.

[0233] In general, by breaking the symmetry of an organic compound, the crystallinity decreases, and the solubility in organic solvents improves.

[0234] R in general formula (A-2) 5 and R 6 is substituted only on the ring carbon atoms on one side of the axis of symmetry of the molecule, so the molecule has low symmetry. In other words, a cycloolefin monomer having a structure represented by general formula (A-2) has high solubility and is therefore suitable for producing a film by a solution casting method.

[0235] The content of the cycloolefin monomer having the structure represented by general formula (A-2) in the polymer of cycloolefin monomers can be, for example, 70 mol% or more, preferably 80 mol% or more, and more preferably 100 mol% relative to the total of all cycloolefin monomers constituting the cycloolefin resin.

[0236] When the cycloolefin monomer having the structure represented by general formula (A-2) is contained in a certain amount or more, the orientation of the resin is enhanced, and the phase difference (retardation) value is likely to increase.

[0237] Specific examples of cycloolefin monomers having a structure represented by general formula (A-1) are shown below as exemplary compounds 1 to 14, and specific examples of cycloolefin monomers having a structure represented by general formula (A-2) are shown below as exemplary compounds 15 to 34.

[0238] [ka]

[0239] Examples of the copolymerizable monomer copolymerizable with the cycloolefin monomer include a copolymerizable monomer capable of ring-opening copolymerization with the cycloolefin monomer, and a copolymerizable monomer capable of addition copolymerization with the cycloolefin monomer.

[0240] Examples of copolymerizable monomers capable of ring-opening copolymerization include cycloolefins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, and dicyclopentadiene.

[0241] Examples of copolymerizable monomers capable of addition copolymerization include unsaturated double bond-containing compounds, vinyl-based cyclic hydrocarbon monomers, and (meth)acrylates.

[0242] Examples of the unsaturated double bond-containing compound include olefinic compounds having 2 to 12 carbon atoms (preferably 2 to 8 carbon atoms), and examples thereof include ethylene, propylene, and butene.

[0243] Examples of the vinyl-based cyclic hydrocarbon monomer include vinylcyclopentene-based monomers such as 4-vinylcyclopentene and 2-methyl-4-isopropenylcyclopentene.

[0244] Examples of the (meth)acrylate include alkyl (meth)acrylates having 1 to 20 carbon atoms, such as methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and cyclohexyl (meth)acrylate.

[0245] The content of the cycloolefin monomer in the copolymer of a cycloolefin monomer and a copolymerizable monomer can be, for example, within the range of 20 to 80 mol %, preferably within the range of 30 to 70 mol %, relative to the sum of all monomers constituting the copolymer.

[0246] As described above, the cycloolefin resin is a polymer obtained by polymerizing or copolymerizing a cycloolefin monomer having a norbornene skeleton, preferably a cycloolefin monomer having a structure represented by general formula (A-1) or (A-2), and examples thereof include the following polymers (1) to (7).

[0247] (1) Ring-opening polymer of cycloolefin monomer (2) Ring-opening copolymers of cycloolefin monomers and copolymerizable monomers capable of ring-opening copolymerization with the cycloolefin monomers. (3) Hydrogenated ring-opening (co)polymer of (1) or (2) above (4) A (co)polymer obtained by cyclizing the ring-opening (co)polymer of (1) or (2) above by the Friedel-Crafts reaction and then adding hydrogen. (5) Saturated copolymer of cycloolefin monomer and unsaturated double bond-containing compound (6) Addition copolymers of cycloolefin monomers with vinyl cyclic hydrocarbon monomers and their hydrogenated products (7) Alternating copolymer of cycloolefin monomer and (meth)acrylate

[0248] The polymers (1) to (7) above can all be obtained by known methods, for example, the methods described in JP-A Nos. 2008-107534 and 2005-227606.

[0249] For example, the catalyst and solvent used in the ring-opening copolymerization (2) above may be those described in paragraphs 0019 to 0024 of JP-A No. 2008-107534.

[0250] As the catalyst used for the hydrogenated products (3) and (6) above, for example, those described in paragraphs 0025 to 0028 of JP-A No. 2008-107534 can be used.

[0251] The acidic compound used in the Friedel-Crafts reaction (4) above can be, for example, the one described in paragraph 0029 of JP-A No. 2008-107534.

[0252] As the catalyst used in the addition polymerization of the above (5) to (7), for example, those described in paragraphs 0058 to 0063 of JP-A No. 2005-227606 can be used.

[0253] The alternating copolymerization reaction (7) above can be carried out by, for example, the method described in paragraphs 0071 and 0072 of JP-A No. 2005-227606.

[0254] Among these, the polymers (1) to (3) and (5) are preferred, and the polymers (3) and (5) are more preferred.

[0255] That is, the cycloolefin-based resin preferably contains at least one of a structural unit represented by the following general formula (B-1) and a structural unit represented by the following general formula (B-2), in order to increase the glass transition temperature and light transmittance of the resulting cycloolefin-based resin, and more preferably contains only a structural unit represented by the general formula (B-2), or contains both a structural unit represented by the general formula (B-1) and a structural unit represented by the general formula (B-2).

[0256] The structural unit represented by general formula (B-1) is a structural unit derived from the cycloolefin monomer represented by the above-mentioned general formula (A-1), and the structural unit represented by general formula (B-2) is a structural unit derived from the cycloolefin monomer represented by the above-mentioned general formula (A-2).

[0257] [ka]

[0258] In the general formula (B-1), X represents -CH=CH- or -CH2CH2-. 1 ~R 4 and p are R in general formula (A-1), 1 ~R 4 and p.

[0259] [ka]

[0260] In the general formula (B-2), X represents -CH=CH- or -CH2CH2-. 5 ~R 6 and p are R in general formula (A-2), 5 ~R 6 and p.

[0261] The cycloolefin resin according to the present invention may be a commercially available product. Examples of commercially available cycloolefin resins include Arton G (for example, G7810), Arton F, Arton R (for example, R4500, R4900, and R5000), and Arton RX, all manufactured by JSR Corporation.

[0262] The intrinsic viscosity [η]inh of cycloolefin resin is 0.2 to 5 cm when measured at 30°C. 3 / g, and 0.3 to 3 cm 3 / g, and more preferably in the range of 0.4 to 1.5 cm 3 It is more preferable that the content is in the range of / g.

[0263] The number average molecular weight (Mn) of the cycloolefin resin is preferably within a range of 8,000 to 100,000, more preferably within a range of 10,000 to 80,000, and even more preferably within a range of 12,000 to 50,000.

[0264] The weight average molecular weight (Mw) of the cycloolefin resin is preferably within a range of 20,000 to 300,000, more preferably within a range of 30,000 to 250,000, and even more preferably within a range of 40,000 to 200,000.

[0265] The number average molecular weight and weight average molecular weight of the cycloolefin resin can be measured in terms of polystyrene by gel permeation chromatography (GPC).

[0266] (Gel Permeation Chromatography) Solvent: methylene chloride Column: Shodex K806, K805, K803G (three columns connected together, manufactured by Showa Denko K.K.) Column temperature: 25℃ Sample concentration: 0.1% by mass Detector: RI Model 504 (GL Sciences) Pump: L6000 (Hitachi, Ltd.) Flow rate: 1.0mL / min Calibration curve: A calibration curve was used using 13 samples of standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) in the range of Mw=500 to 2,800,000. It is preferable to use the 13 samples at approximately equal intervals.

[0267] When the intrinsic viscosity [η]inh, number average molecular weight and weight average molecular weight are within the above ranges, the cycloolefin resin has good heat resistance, water resistance, chemical resistance, mechanical properties and moldability into a film.

[0268] The glass transition temperature Tg [°C] of the cycloolefin resin is usually 110°C or higher, preferably in the range of 110 to 350°C, more preferably in the range of 120 to 250°C, and even more preferably in the range of 120 to 220°C.

[0269] When the glass transition temperature Tg [°C] is 110°C or higher, deformation under high temperature conditions is easily suppressed. On the other hand, if the glass transition temperature Tg [°C] is 350°C or lower, molding is easy and deterioration of the resin due to heat during molding is easily suppressed.

[0270] The content of the cycloolefin resin is preferably 70% by mass or more, and more preferably 80% by mass or more, based on the film.

[0271] (3.1.2) Acrylic resin The acrylic resin according to the present invention is a polymer of an acrylic acid ester or a methacrylic acid ester, and also includes copolymers with other monomers. Therefore, the acrylic resin according to the present invention also includes methacrylic resin.

[0272] The resin is not particularly limited, but is preferably one containing methyl methacrylate units in the range of 50 to 99% by mass and other monomer units copolymerizable therewith in the range of 1 to 50% by mass.

[0273] Other units constituting the acrylic resin formed by copolymerization include alkyl methacrylates having 2 to 18 carbon atoms in the alkyl group, alkyl acrylates having 1 to 18 carbon atoms in the alkyl group, hydroxyalkyl acrylates such as isobornyl methacrylate and 2-hydroxyethyl acrylate, α,β-unsaturated acids such as acrylic acid and methacrylic acid, acrylamides such as acryloylmorpholine and N-hydroxyphenylmethacrylamide, unsaturated group-containing dicarboxylic acids such as N-vinylpyrrolidone, maleic acid, fumaric acid, and itaconic acid, aromatic vinyl compounds such as styrene and α-methylstyrene, α,β-unsaturated nitriles such as acrylonitrile and methacrylonitrile, maleic anhydride, maleimide, N-substituted maleimide, glutarimide, and glutaric anhydride.

[0274] Examples of copolymerizable monomers that form units obtained by excluding glutarimide and glutaric anhydride from the above units include monomers corresponding to the above units.

[0275] That is, examples of the monomer include alkyl methacrylates having 2 to 18 carbon atoms in the alkyl group, alkyl acrylates having 1 to 18 carbon atoms in the alkyl group, hydroxyalkyl acrylates such as isobornyl methacrylate and 2-hydroxyethyl acrylate, α,β-unsaturated acids such as acrylic acid and methacrylic acid, acrylamides such as acryloylmorpholine and N-hydroxyphenylmethacrylamide, unsaturated group-containing dicarboxylic acids such as N-vinylpyrrolidone, maleic acid, fumaric acid, and itaconic acid, aromatic vinyl compounds such as styrene and α-methylstyrene, α,β-unsaturated nitriles such as acrylonitrile and methacrylonitrile, maleic anhydride, maleimide, and N-substituted maleimide.

[0276] Furthermore, glutarimide units can be formed, for example, by reacting an intermediate resin having a (meth)acrylic acid ester unit with a primary amine (imidizing agent) to effect imidization (see JP-A No. 2011-26563).

[0277] The glutaric anhydride unit can be formed, for example, by heating an intermediate resin having a (meth)acrylic acid ester unit (see Japanese Patent No. 4961164).

[0278] Of the above structural units, it is particularly preferred that the acrylic resin according to the present invention contains isobornyl methacrylate, acryloylmorpholine, N-hydroxyphenylmethacrylamide, N-vinylpyrrolidone, styrene, hydroxyethyl methacrylate, maleic anhydride, maleimide, N-substituted maleimide, glutaric anhydride, or glutarimide, from the viewpoint of mechanical strength.

[0279] The acrylic resin according to the present invention preferably has a weight average molecular weight (Mw) in the range of 50,000 to 1,000,000, more preferably in the range of 100,000 to 1,000,000, and particularly preferably in the range of 200,000 to 800,000, from the viewpoint of controlling dimensional changes due to changes in the environmental temperature and humidity, and from the viewpoint of improving peelability from metal supports during film production, drying properties in organic solvents, heat resistance, and mechanical strength.

[0280] If it is 50,000 or more, the heat resistance and mechanical strength are excellent, and if it is 1,000,000 or less, the peelability from the metal support and the drying property of the organic solvent are excellent.

[0281] The method for producing the acrylic resin according to the present invention is not particularly limited, and any of the known methods such as suspension polymerization, emulsion polymerization, bulk polymerization, and solution polymerization may be used.

[0282] Here, as the polymerization initiator, ordinary peroxide-based and azo-based initiators can be used, and also redox-based initiators can be used.

[0283] The polymerization temperature may be within a range of 30 to 100°C for suspension or emulsion polymerization, and within a range of 80 to 160°C for bulk or solution polymerization.

[0284] In order to control the reduced viscosity of the resulting copolymer, the polymerization may be carried out using an alkyl mercaptan or the like as a chain transfer agent.

[0285] The glass transition temperature Tg [°C] of the acrylic resin is preferably within the range of 80 to 120°C from the viewpoint of maintaining the mechanical strength of the film.

[0286] As the acrylic resin according to the present invention, commercially available products can also be used. Examples include Delpet 60N, 80N, 980N, and SR8200 (all manufactured by Asahi Kasei Chemicals Corporation), Dianal BR52, BR80, BR83, BR85, BR88, EMB-143, EMB-159, EMB-160, EMB-161, EMB-218, EMB-229, EMB-270, and EMB-273 (all manufactured by Mitsubishi Rayon Co., Ltd.), KT75, TX400S, and IPX012 (all manufactured by Denki Kagaku Kogyo Co., Ltd.), and the like. Two or more types of acrylic resins can also be used in combination.

[0287] The acrylic resin according to the present invention preferably contains an additive, and as an example of the additive, it is preferable to contain acrylic particles (rubber elastomer particles) described in WO 2010 / 001668 in order to improve the mechanical strength of the film and adjust the dimensional change rate.

[0288] Examples of commercially available products of such multilayered acrylic granular composites include "Metablen W-341" manufactured by Mitsubishi Rayon Co., Ltd., "Kane Ace" manufactured by Kaneka Corporation, "Paraloid" manufactured by Kureha Corporation, "Acryloid" manufactured by Rohm and Haas Company, "Staphyloid" manufactured by Aica Corporation, Chemisnow MR-2G, MS-300X (all manufactured by Soken Chemical & Engineering Co., Ltd.), and "Parapet SA" manufactured by Kuraray Co., Ltd., and these may be used alone or in combination.

[0289] The volume average particle size of the acrylic particles is 0.35 μm or less, preferably in the range of 0.01 to 0.35 μm, and more preferably in the range of 0.05 to 0.30 μm. If the particle size is equal to or larger than a certain level, the film can be easily stretched under heat, and if the particle size is equal to or smaller than a certain level, the transparency of the resulting film is less likely to be impaired.

[0290] From the viewpoint of flexibility, the film of the present invention preferably has a flexural modulus (JIS K7171) of 10.5 GPa or less, more preferably 1.3 GPa or less, and even more preferably 1.2 GPa or less.

[0291] The above-mentioned flexural modulus varies depending on the type and amount of the acrylic resin and rubber elastomer particles in the film. For example, the greater the content of rubber elastomer particles, the smaller the flexural modulus generally becomes.

[0292] Furthermore, when a copolymer of alkyl methacrylate and alkyl acrylate or the like is used as the acrylic resin, the flexural modulus is generally smaller than when a homopolymer of alkyl methacrylate is used.

[0293] (3.1.3) Cellulose ester resin In the film roll of the present invention, it is also preferable to use a cellulose ester resin.

[0294] The cellulose ester used in the present invention refers to a cellulose acylate resin in which some or all of the hydrogen atoms of the hydroxyl groups (-OH) at the 2nd, 3rd, and 6th positions in the β-1,4-bonded glucose units that constitute cellulose are substituted with acyl groups.

[0295] The above cellulose ester is not particularly limited, but is preferably an ester of a linear or branched carboxylic acid having about 2 to 22 carbon atoms. The carboxylic acid constituting the ester may be an aliphatic carboxylic acid, may form a ring, or may be an aromatic carboxylic acid.

[0296] Examples of the above include cellulose esters in which the hydrogen atom of the hydroxy group portion of cellulose is substituted with an acyl group having 2 to 22 carbon atoms, such as an acetyl group, a propionyl group, a butyryl group, an isobutyryl group, a valeryl group, a pivaloyl group, a hexanoyl group, an octanoyl group, a lauroyl group, or a stearoyl group.

[0297] The carboxylic acid (acyl group) constituting the ester may have a substituent. The carboxylic acid constituting the ester is preferably a lower fatty acid having 6 or less carbon atoms, more preferably a lower fatty acid having 3 or less carbon atoms.

[0298] The cellulose ester may contain a single type of acyl group or a combination of multiple acyl groups.

[0299] Specific examples of preferred cellulose esters include cellulose acetates such as diacetyl cellulose (DAC) and triacetyl cellulose (TAC), as well as mixed fatty acid esters of cellulose to which a propionate group or a butyrate group is bonded in addition to an acetyl group, such as cellulose acetate propionate (CAP), cellulose acetate butyrate, and cellulose acetate propionate butyrate. These cellulose esters may be used singly or in combination of two or more kinds.

[0300] (Type of acyl group, degree of substitution) By adjusting the type and degree of substitution of the acyl group of the cellulose ester, the humidity fluctuation of the retardation can be controlled within a desired range, and the uniformity of the film thickness can be improved.

[0301] The smaller the substitution degree of the acyl group in the cellulose ester, the more improved the retardation is, and thus the thinner the film can be made. On the other hand, if the degree of substitution of the acyl group is too small, the durability may be deteriorated, which is undesirable.

[0302] On the other hand, the greater the substitution degree of the acyl group in the cellulose ester, the less retardation is exhibited, so it is necessary to increase the stretching ratio during film formation. However, it is difficult to achieve uniform stretching at a high stretching ratio, which results in greater (worsening) variation in film thickness.

[0303] Furthermore, the Rt humidity fluctuation, which is the retardation (phase difference) in the thickness direction, occurs when water molecules coordinate with the carbonyl groups of cellulose, so the higher the degree of acyl group substitution, i.e., the more carbonyl groups there are in the cellulose, the worse the Rt humidity fluctuation tends to be.

[0304] The cellulose ester preferably has a total degree of substitution in the range of 2.1 to 2.5. By setting the temperature in this range, environmental fluctuations (especially Rt fluctuations due to humidity) can be suppressed, and the uniformity of the film thickness can be improved.

[0305] More preferably, it is in the range of 2.2 to 2.45, from the viewpoint of improving the flowability and stretchability during film formation and further improving the uniformity of the film thickness.

[0306] More specifically, the cellulose ester satisfies both of the following formulae (a) and (b): In the formulae (a) and (b), X is the degree of substitution of the acetyl group, and Y is the degree of substitution of the propionyl group or the butyryl group, or the degree of substitution of a mixture thereof.

[0307] Formula (a): 2.1≦X+Y≦2.5 Formula (b): 0≦Y≦1.5

[0308] The cellulose ester is preferably cellulose acetate (Y=0) or cellulose acetate propionate (CAP) (Y: propionyl group, Y>0), and more preferably cellulose acetate where Y=0 in order to reduce variations in film thickness.

[0309] A particularly preferred cellulose acetate is cellulose diacetate (DAC) having a value of 2.1≦X≦2.5 (more preferably 2.15≦X≦2.45) in order to keep retardation expression, Rt humidity fluctuation, and film thickness variation within desired ranges.

[0310] When Y>0, cellulose acetate propionate (CAP) is particularly preferably used, where X satisfies 0.95≦X≦2.25, 0.1≦Y≦1.2, and 2.15≦X+Y≦2.45.

[0311] By using the above-mentioned cellulose acetate or cellulose acetate propionate, a film roll having excellent retardation, mechanical strength, and resistance to environmental changes can be obtained.

[0312] The degree of acyl substitution indicates the average number of acyl groups per glucose unit, and indicates how many hydrogen atoms of the hydroxy groups at the 2nd, 3rd, and 6th positions of one glucose unit are substituted with acyl groups. Therefore, the maximum degree of substitution is 3.0, which means that all of the hydrogen atoms of the hydroxy groups at the 2-, 3-, and 6-positions are substituted with acyl groups.

[0313] These acyl groups may be substituted evenly at the 2-, 3- and 6-positions of the glucose units, or may be substituted with a distribution. The degree of substitution is determined by the method specified in ASTM-D817-96.

[0314] To obtain desired optical properties, cellulose acetates having different degrees of substitution may be mixed and used. In the above case, the mixing ratio of different cellulose acetates is not particularly limited.

[0315] The number average molecular weight (Mn) of cellulose ester is 2×10 4 ~3×10 5 in the range of 2×10 4 ~1.2×10 5 in the range of 4×10 4 ~8×10 4 Within this range, the mechanical strength of the resulting film roll is increased, which is preferable.

[0316] The number average molecular weight (Mn) of the cellulose ester is calculated by measurement using gel permeation chromatography (GPC) under the above-mentioned measurement conditions.

[0317] The weight average molecular weight (Mw) of the cellulose ester is 2 × 10 4 ~1×10 6 in the range of 2×10 4 ~1.2×10 5 in the range of 4×10 4 ~8×104 It is preferable that the thickness is within this range in view of increasing the mechanical strength of the resulting film roll.

[0318] The raw cellulose for the cellulose ester is not particularly limited, but examples thereof include cotton linter, wood pulp, and kenaf. The cellulose esters obtained from these materials can be mixed and used in any desired ratio.

[0319] Cellulose esters such as cellulose acetate and cellulose acetate propionate can be produced by known methods.

[0320] Generally, the raw material cellulose is mixed with a specific organic acid (acetic acid, propionic acid, etc.), an acid anhydride (acetic anhydride, propionic anhydride, etc.), and a catalyst (sulfuric acid, etc.), and the cellulose is esterified, and the reaction is continued until a cellulose triester is produced.

[0321] In triesters, the three hydroxy groups of the glucose unit are replaced with the acyl group of an organic acid.

[0322] When two kinds of organic acids are used at the same time, mixed ester type cellulose esters, such as cellulose acetate propionate and cellulose acetate butyrate, can be prepared.

[0323] Next, the cellulose triester is hydrolyzed to synthesize a cellulose ester resin having a desired degree of acyl substitution. Thereafter, the cellulose ester resin is completed through steps such as filtration, precipitation, washing with water, dehydration, drying, etc. Specifically, the cellulose ester resin can be synthesized by referring to the method described in JP-A-10-45804.

[0324] (3.2) Other additives The film roll of the present invention may contain the following additives in addition to the above-mentioned thermoplastic resin.

[0325] (3.2.1) Plasticizers The film roll of the present invention preferably contains at least one type of plasticizer for the purpose of imparting processability to, for example, a polarizing plate protective film. The plasticizers are preferably used alone or in combination.

[0326] Among plasticizers, it is preferable to include at least one plasticizer selected from the group consisting of sugar esters, polyesters, and styrene-based compounds, from the viewpoint of achieving both effective control of moisture permeability and high compatibility with base resins such as cellulose esters.

[0327] The molecular weight of the plasticizer is preferably 15,000 or less, more preferably 10,000 or less, from the viewpoint of achieving both improved resistance to moist heat and compatibility with base resins such as cellulose esters.

[0328] When the compound having a molecular weight of 10,000 or less is a polymer, it preferably has a weight average molecular weight (Mw) of 10,000 or less. The weight average molecular weight (Mw) is preferably in the range of 100 to 10,000, and more preferably in the range of 400 to 8,000.

[0329] In particular, to obtain the effects of the present invention, it is preferable to contain the compound having a molecular weight of 1500 or less in an amount within the range of 6 to 40 parts by mass, and more preferably within the range of 10 to 20 parts by mass, per 100 parts by mass of the base resin. By containing the component within the above range, it is possible to effectively control the moisture permeability and also to ensure compatibility with the base resin, which is preferable.

[0330] (sugar esters) The film roll of the present invention may contain a sugar ester compound for the purpose of preventing hydrolysis.

[0331] Specifically, the sugar ester compound may be a sugar ester having 1 to 12 of at least one kind of pyranose structure or furanose structure, in which all or some of the OH groups in the structure have been esterified.

[0332] (polyester) The film roll of the present invention may contain polyester.

[0333] The polyester is not particularly limited, but examples thereof include a polymer (polyester polyol) having a terminal hydroxy group that can be obtained by a condensation reaction between a dicarboxylic acid or an ester-forming derivative thereof and a glycol, and a polymer (terminal-capped polyester) in which the terminal hydroxy group of the polyester polyol is capped with a monocarboxylic acid.

[0334] The ester-forming derivatives referred to here include esters of dicarboxylic acids, dicarboxylic acid chlorides, and dicarboxylic acid anhydrides.

[0335] (styrene compounds) In the film roll of the present invention, a styrene-based compound may be used in addition to or instead of the sugar ester and polyester for the purpose of improving the water resistance of the film.

[0336] The styrene-based compound may be a homopolymer of a styrene-based monomer, or a copolymer of a styrene-based monomer and another copolymerizable monomer.

[0337] The content of structural units derived from styrene monomers in the styrene compound is preferably within a range of 30 to 100 mol %, more preferably within a range of 50 to 100 mol %, so that the molecular structure has a certain level of bulkiness.

[0338] Examples of styrene-based monomers include styrene; alkyl-substituted styrenes such as α-methylstyrene, β-methylstyrene, and p-methylstyrene; halogen-substituted styrenes such as 4-chlorostyrene and 4-bromostyrene; hydroxystyrenes such as p-hydroxystyrene, α-methyl-p-hydroxystyrene, 2-methyl-4-hydroxystyrene, and 3,4-dihydroxystyrene; vinylbenzyl alcohols; alkoxy-substituted styrenes such as p-methoxystyrene, p-tert-butoxystyrene, and m-tert-butoxystyrene; 3-vinylbenzoic acid, 4-vinylbenzoic acid, and the like. vinylbenzoates such as benzoic acid; 4-vinylbenzyl acetate; 4-acetoxystyrene; amidostyrenes such as 2-butylamidostyrene, 4-methylamidostyrene, and p-sulfonamidostyrene; aminostyrenes such as 3-aminostyrene, 4-aminostyrene, 2-isopropenylaniline, and vinylbenzyldimethylamine; nitrostyrenes such as 3-nitrostyrene and 4-nitrostyrene; cyanostyrenes such as 3-cyanostyrene and 4-cyanostyrene; vinylphenylacetonitrile; arylstyrenes such as phenylstyrene, and indenes. The styrene-based monomer may be one type or a combination of two or more types.

[0339] (3.2.2) Optional components The film roll of the present invention may contain other optional ingredients such as antioxidants, colorants, ultraviolet absorbers, matting agents, acrylic particles, hydrogen-bonding solvents, and ionic surfactants. These components can be added in an amount of 0.01 to 20 parts by mass per 100 parts by mass of the base resin.

[0340] (antioxidant) In the film roll of the present invention, commonly known antioxidants can be used. In particular, lactone-based, sulfur-based, phenol-based, double bond-based, hindered amine-based, and phosphorus-based compounds can be preferably used.

[0341] These antioxidants and the like are added in an amount of 0.05 to 20% by mass, preferably 0.1 to 1% by mass, based on the resin that is the main raw material of the film. A synergistic effect can be obtained by using several different compounds in combination with these antioxidants rather than using only one type. For example, it is preferable to use lactone-based, phosphorus-based, phenol-based and double bond-based compounds in combination.

[0342] (coloring agent) The film roll of the present invention preferably contains a colorant for adjusting the color tone, within a range that does not impair the effects of the present invention.

[0343] The colorant means a dye or pigment, and in the present invention refers to a dye or pigment that has the effect of making the color tone of the liquid crystal screen blue, adjusting the yellow index, or reducing haze.

[0344] As the colorant, various dyes and pigments can be used, but anthraquinone dyes, azo dyes, phthalocyanine pigments, etc. are effective.

[0345] (ultraviolet absorber) The film roll of the present invention can be used on the viewing side or backlight side of a polarizing plate, and therefore may contain an ultraviolet absorber for the purpose of imparting an ultraviolet absorbing function.

[0346] The ultraviolet absorber is not particularly limited, but examples thereof include ultraviolet absorbers such as benzotriazole-based, 2-hydroxybenzophenone-based, and salicylic acid phenyl ester-based ultraviolet absorbers.

[0347] Examples include triazoles such as 2-(5-methyl-2-hydroxyphenyl)benzotriazole, 2-[2-hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, and 2-(3,5-di-t-butyl-2-hydroxyphenyl)benzotriazole, and benzophenones such as 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, and 2,2′-dihydroxy-4-methoxybenzophenone. The above ultraviolet absorbents may be used singly or in combination of two or more.

[0348] The amount of ultraviolet absorber used varies depending on the type of ultraviolet absorber, conditions of use, etc., but is generally added in the range of 0.05 to 10 mass %, preferably 0.1 to 5 mass %, relative to the base resin.

[0349] (fine particles) The film roll of the present invention preferably contains fine particles that impart slipperiness to the film roll. In particular, the addition of fine particles is effective from the viewpoint of improving the slipperiness of the film surface according to the present invention, improving the slipperiness during winding, and preventing the occurrence of scratches and blocking.

[0350] The fine particles may be either inorganic or organic as long as they do not impair the transparency of the resulting film roll and are heat resistant when melted, but inorganic fine particles are more preferred. These fine particles can be used alone or in combination of two or more kinds.

[0351] By using particles with different particle sizes and shapes (for example, needle-like and spherical), it is possible to achieve both high transparency and lubricity.

[0352] Among the compounds constituting the above-mentioned fine particles, silicon dioxide is particularly preferably used because it has a refractive index close to that of the cycloolefin resin, acrylic resin, and cellulose ester resin and therefore has excellent transparency (haze).

[0353] Specific examples of silicon dioxide that can be preferably used include commercially available products with trade names such as Aerosil (registered trademark) 200V, Aerosil (registered trademark) R972V, Aerosil (registered trademark) R972, R974, R812, 200, 300, R202, OX50, TT600, and NAX50 (all manufactured by Nippon Aerosil Co., Ltd.), Seahoster (registered trademark) KEP-10, Seahoster (registered trademark) KEP-30, and Seahoster (registered trademark) KEP-50 (all manufactured by Nippon Shokubai Co., Ltd.), Silohorbic (registered trademark) 100 (manufactured by Fuji Silysia Co., Ltd.), Nipsil (registered trademark) E220A (manufactured by Nippon Silica Kogyo Co., Ltd.), and Admafine (registered trademark) SO (manufactured by Admatechs Co., Ltd.).

[0354] The shape of the particles is not particularly limited and may be irregular, acicular, flat, spherical, etc., but spherical particles are particularly preferred as they can improve the transparency of the resulting film roll.

[0355] If the particle size is close to the wavelength of visible light, the light will be scattered and transparency will be reduced, so the particle size is preferably smaller than the wavelength of visible light, and more preferably 1 / 2 or less of the wavelength of visible light.

[0356] If the particle size is too small, the lubricity may not be improved, so it is particularly preferable that the particle size is within the range of 80 to 180 nm. The particle size means the size of the aggregate when the particle is an aggregate of primary particles. When the particle is not spherical, the particle diameter means the diameter of a circle equivalent to the projected area of ​​the particle.

[0357] The fine particles are preferably added in an amount within a range of 0.05 to 10% by mass, and more preferably within a range of 0.1 to 5% by mass, relative to the base resin.

[0358] 4. Polarizing plate A part of the film in the film roll of the present invention can be suitably used when it is provided in a polarizing plate. A polarizing plate generally comprises a polarizer film (also called a "polarizing film" or "polarizer film") and transparent resin films laminated on both sides of the polarizer film. A portion of the film in the film roll of the present invention can be included in the polarizing plate as, for example, the resin film.

[0359] The polarizing plate may have a structure including, for example, a polarizer layer using a polarizer film, a polarizer protective film using a resin film, and an adhesive layer disposed therebetween.

[0360] (4.1) Polarizer Layer The polarizer layer is a layer made of at least a polarizer film. Here, the term "polarizer" refers to an element that transmits only light polarized in a certain direction.

[0361] Examples of polarizing films include polyvinyl alcohol-based polarizing films and cellulose ester-based polarizing films, and polyvinyl alcohol-based resins are preferred because they are superior to cellulose ester-based resins in transparency, optical properties, durability, etc.

[0362] Polyvinyl alcohol polarizing films include those dyed with iodine and those dyed with a dichroic dye.

[0363] The polyvinyl alcohol-based polarizing film may be a polyvinyl alcohol-based film that has been uniaxially stretched and then dyed with iodine or a dichroic dye (preferably a film that has been further subjected to a durability treatment with a boron compound), or a polyvinyl alcohol-based film that has been dyed with iodine or a dichroic dye and then uniaxially stretched (preferably a film that has been further subjected to a durability treatment with a boron compound). The absorption axis of the polarizer layer is usually parallel to the direction of maximum stretch.

[0364] For example, ethylene-modified polyvinyl alcohols having an ethylene unit content of 1 to 4 mol %, a polymerization degree of 2000 to 4000, and a saponification degree of 99.0 to 99.99 mol %, as described in JP-A Nos. 2003-248123 and 2003-342322, etc., are used.

[0365] The thickness of the polarizer layer is preferably 5 to 30 μm, and more preferably 5 to 20 μm in order to make the polarizing plate thinner.

[0366] (4.2) Polarizing plate protective film A part of the film in the film roll of the present invention can be disposed on at least one surface of the polarizer layer (at least the surface facing the liquid crystal cell) and can be used as a polarizing plate protective film or a retardation film. The surface of the polarizing plate protective film on which the polarizer layer is laminated may be subjected to an activation treatment as described below.

[0367] When a part of the film of the film roll of the present invention is disposed on only one side of the polarizer layer as a polarizing plate protective film, another optical film such as a retardation film may be disposed on the other side of the polarizer layer.

[0368] Other examples of optical films include commercially available cellulose ester films (e.g., Konica Minolta TAC KC8UX, KC5UX, KC4UX, KC8UCR3, KC4SR, KC4BR, KC4CR, KC4DR, KC4FR, KC4KR, KC8UY, KC6UY, KC4UY, KC4UE, KC8UE, KC8UY-HA, KC2UA, KC4UA , KC6UA, KC8UA, KC2UAH, KC4UAH, KC6UAH, all manufactured by Konica Minolta, Inc.; Fujitac T40UZ, Fujitac T60UZ, Fujitac T80UZ, Fujitac TD80UL, Fujitac TD60UL, Fujitac TD40UL, Fujitac R02, Fujitac R06, all manufactured by Fujifilm Corporation.

[0369] The thickness of the other optical film may be, for example, 5 to 100 μm, preferably 40 to 80 μm.

[0370] (4.3) Adhesive layer The adhesive layer is a dried water-based adhesive or ultraviolet-curable adhesive disposed between a part of the film of the film roll of the present invention (or another optical film) and the polarizer layer.

[0371] The thickness of the adhesive layer may be, for example, about 0.01 to 10 μm, and preferably about 0.03 to 5 μm.

[0372] (water-based adhesive) Examples of water-based adhesives include vinyl-based, gelatin-based, vinyl-latex-based, polyurethane-based, isocyanate-based, polyester-based, and epoxy-based adhesives.

[0373] When a polyvinyl alcohol-based polarizing film is used for the polarizer layer, from the viewpoint of easily obtaining adhesiveness, an aqueous adhesive containing a vinyl-based resin is preferred, and an aqueous adhesive containing a polyvinyl alcohol-based resin (such as a fully saponified polyvinyl alcohol aqueous solution) is more preferred.

[0374] The water-based adhesive containing a polyvinyl alcohol-based resin may further contain a water-soluble crosslinking agent such as boric acid, borax, glutaraldehyde, melamine, or oxalic acid.

[0375] (UV-curing adhesive) The ultraviolet-curable adhesive may be a photo-radical polymerizable composition or a photo-cationic polymerizable composition. Among these, photocationically polymerizable compositions are preferred.

[0376] The photocationically polymerizable composition contains an epoxy compound and a photocationic polymerization initiator.

[0377] An epoxy compound is a compound having one or more, preferably two or more, epoxy groups in the molecule.

[0378] Examples of epoxy compounds include hydrogenated epoxy compounds (glycidyl ethers of polyols having alicyclic rings) obtained by reacting alicyclic polyols with epichlorohydrin; aliphatic epoxy compounds such as polyglycidyl ethers of aliphatic polyhydric alcohols or their alkylene oxide adducts; and alicyclic epoxy compounds having one or more epoxy groups bonded to an alicyclic ring in the molecule. The epoxy compounds may be used alone or in combination of two or more.

[0379] The photocationic polymerization initiator may be, for example, an aromatic diazonium salt; an onium salt such as an aromatic iodonium salt or an aromatic sulfonium salt; or an iron-arene complex.

[0380] The cationic photopolymerization initiator may further contain additives such as a cationic polymerization accelerator such as oxetane or polyol, a photosensitizer, and a solvent, as required.

[0381] (4.4) Polarizing Plate Manufacturing Method The method for manufacturing a polarizing plate according to the present invention comprises the steps of: 1) subjecting the surface of a polarizing plate protective film to an activation treatment; 2) laminating a polarizer layer (polarizing film) onto the activated surface of the polarizing plate protective film via a water-based adhesive or an ultraviolet-curable adhesive; and 3) drying the resulting laminate.

[0382] Regarding step 1) The surface of the polarizing plate protective film (the surface to be bonded to the polarizer layer) is subjected to an activation treatment. This makes it easier to obtain adhesion to the polarizer layer.

[0383] Specifically, the activation treatment hydrophilizes the siloxane bonds, ether bonds, tertiary carbon atoms, etc. in the side chains of specific graft polymers contained in the polarizing plate protective film, thereby increasing their affinity with water-based adhesives and facilitating their interaction, thereby facilitating adhesion between the polarizing plate protective film and the polarizer layer.

[0384] Examples of the activation treatment include corona treatment, plasma treatment and saponification treatment, preferably corona treatment and plasma treatment, more preferably corona treatment.

[0385] The activation treatment conditions may be such that the siloxane bond, ether bond, tertiary carbon atom, etc. contained in the side chain of the specific graft polymer can be sufficiently activated. When the activation treatment is a corona treatment, the irradiation dose is 100 to 1000 [W·min / m 2 ], and 150 to 900 [W·min / m 2 It is more preferable that the range is within the range of .

[0386] Regarding step 2) Next, a polarizer layer is laminated on the activated surface of the polarizing plate protective film via a water-based adhesive or an ultraviolet-curable adhesive.

[0387] Regarding step 3) The resulting laminate is then dried to obtain a polarizing plate.

[0388] Drying can be carried out by heating. The drying temperature may be any temperature at which the water-based adhesive or the ultraviolet-curable adhesive is sufficiently dried, and may be within the range of, for example, 60 to 100°C.

[0389] 5.Display device A part of the film in the film roll of the present invention can be suitably used when it is provided in a display device. Examples of the display device include various image display devices such as liquid crystal display devices and organic EL display devices. As an example of the use of a part of the film roll of the present invention, the case where it is provided as a polarizer protective film in a polarizer and a liquid crystal display device will be described below.

[0390] (5.1) Liquid crystal display device A specific example of the display device of the present invention is a liquid crystal display device including a liquid crystal cell and a pair of polarizing plates sandwiching the liquid crystal cell.

[0391] FIG. 18 is a schematic diagram showing an example of the configuration of a liquid crystal display device of the present invention. As shown in FIG. 18, the liquid crystal display device ( 2 00) includes a liquid crystal cell (220), a first polarizing plate (210) and a second polarizing plate (230) that sandwich the cell, and a backlight (240).

[0392] The display mode of the liquid crystal cell (220) may be various display modes such as STN, TN, OCB, HAN, VA (MVA, PVA), IPS, etc., and the VA (MVA, PVA) mode is preferable to obtain high contrast.

[0393] The first polarizing plate (210) includes a first polarizer (212), a polarizing plate protective film (211) arranged on the surface of the first polarizer (212) opposite the liquid crystal cell, and a polarizing plate protective film (213) arranged on the surface of the first polarizer (212) facing the liquid crystal cell.

[0394] The second polarizing plate (230) includes a second polarizer (232), a polarizer protective film (231) disposed on the surface of the second polarizer (232) facing the liquid crystal cell, and a polarizer protective film (233) disposed on the surface of the second polarizer (232) opposite the liquid crystal cell. One of the polarizer protective films (213) and (231) can be omitted, if necessary.

[0395] At least one of the polarizing plate protective films (211) and (233) can be the resin film according to the present invention.

[0396] (5.2) Other uses Some films in the film roll of the present invention can be preferably used not only as polarizing plate protective films for liquid crystal display devices, but also as protective films for image display devices such as touch panels, organic EL displays, and plasma displays.

[0397] The embodiments to which the present invention can be applied are not limited to the above-described embodiments, and can be modified as appropriate without departing from the spirit of the present invention. [Example]

[0398] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these. In the examples, the terms "parts" and "%" are used, but unless otherwise specified, they represent "parts by mass" or "% by mass."

[0399] [A. Preparation of film roll] [A.1 Preparation of Film Roll No. 1] The film was formed by a solution casting method.

[0400] (Dope preparation step [S1]) <Synthesis of cyclic polyolefin polymer [P-1]> 100 parts by mass of purified toluene and 100 parts by mass of norbornenecarboxylic acid methyl ester were placed in a stirrer.

[0401] Next, 25 mmol % (based on the monomer mass) of ethylhexanoate-Ni dissolved in toluene, 0.225 mmol % (based on the monomer mass) of tri(pentafluorophenyl)boron, and 0.25 mmol % (based on the monomer mass) of triethylaluminum dissolved in toluene were added to the stirring device. The reaction was carried out at room temperature with stirring for 18 hours.

[0402] After the reaction was completed, the reaction mixture was poured into an excess of ethanol to precipitate a polymer. The precipitate was purified and the resulting polymer was dried in a vacuum oven at 65°C for 24 hours to synthesize a cyclic polyolefin polymer [P-1].

[0403] Preparation of Cyclic Polyolefin Solution (Dope [D-1]) The following composition [1] was placed in a mixing tank, stirred to dissolve each component, and then filtered through a filter paper with an average pore size of 34 μm and a sintered metal filter with an average pore size of 10 μm to prepare a cyclic polyolefin solution (dope [D-1]).

[0404] 《Composition [1]》 Cyclic polyolefin polymer [P-1] 25 parts by mass Dichloromethane 65 parts by mass Ethanol 10 parts by mass

[0405] Preparation of Microparticle Dispersion [1] Next, the following composition [2] was charged into a disperser to prepare a fine particle dispersion [1] as an additive.

[0406] 《Composition [2]》 Fine particles (Aerosil R812: manufactured by Nippon Aerosil Co., Ltd., primary average particle size: 7 nm, apparent specific gravity 50 g / L) 4 parts by mass Dichloromethane 76 parts by mass Ethanol 20 parts by weight

[0407] <Preparation of film-forming dope [1]> 100 parts by mass of the cyclic polyolefin solution (dope [D-1]) and 0.75 parts by mass of the fine particle dispersion [1] were mixed to prepare a membrane-forming dope [1] (resin composition cycloolefin resin: COP).

[0408] (Casting process [S2]) The membrane-forming dope [1] (resin composition, cycloolefin resin: COP) prepared in the dope preparation step [S1] was fed to a casting die through a conduit via a pressure-type metering gear pump, and the dope was cast from the casting die to a casting position on a support consisting of an endless, rotating, stainless steel belt in a width of 1,800 mm on a membrane-forming line. The dope was heated on the support until it became self-supporting, and dried by evaporating the solvent until the cast membrane could be peeled off from the support with a peel roller, thereby forming a cast membrane.

[0409] (Peeling process [S3]) In the casting step [S2], after forming the cast film, the cast film was peeled off from the support by a peeling roller while maintaining its self-supporting property.

[0410] (Shrinkage process [S4]) The film was treated at a high temperature without being held in the width direction, and the density of the film was increased, causing the film to shrink in the width direction at a shrinkage rate of 7%.

[0411] (1st drying process [S5]) The film was then heated on the support to evaporate the solvent. The residual solvent content of the film was measured by the following method and was found to be 5% by mass or less.

[0412] <Residual solvent amount measurement> The amount of residual solvent was determined by mass spectrometry using gas chromatography as follows. That is, a piece of film was taken from any location, and in order to prevent the solvent remaining in the film from volatilizing, it was quickly placed in a vial and sealed. Next, a needle was inserted into the vial and mass spectrometry was performed using a gas chromatograph (Agilent Technologies, Inc.).

[0413] The amount of residual solvent is defined by the following formula: Residual solvent amount [mass%] = {(MN) / N} x 100 In the above formula, M is the mass [g] of a sample taken at any time during or after the production of the cast membrane or film, and N is the mass [g] of the sample after heating at 115°C for 1 hour.

[0414] (1st stretching process [S6]) Thereafter, the film was transported in a tenter stretching device and stretched transversely.

[0415] (1st cutting process [S7]) Both ends of the stretched film in the width direction were cut.

[0416] (Second stretching process [S8]) As in the first stretching step, the film was stretched using a tenter stretching device. The residual solvent amount in the film was measured by the above method and was found to be 1 to 5% by mass.

[0417] (Second cutting process [S9]) Similar to the first cutting step, both ends of the stretched film in the width direction were cut.

[0418] (Second drying process [S10]) As in the first drying step, the film was heated on the support to evaporate the solvent. The residual solvent content of the film was measured by the above method and was found to be 0.1 to 2% by mass.

[0419] (Third cutting process [S11]) Similar to the first cutting step and the second cutting step, both ends of the stretched film in the width direction were cut.

[0420] (Winding process [S12]) The above film was wound up at a winding speed (line speed at which the film is transported) of 60 m / min, with a film roll width of 2000 mm and a wound length of 10000 m. The thickness of the film when wound was measured and found to be 40 μm.

[0421] In addition, using a winding device and TR (touch roller), the touch pressure around the core during winding was adjusted to 16.0 N / m and the tension to 40 N / m, the touch pressure at the center of the winding to 16.0 N / m and the tension to 40 N / m, and the touch pressure around the outer periphery of the winding to 15.2 N / m and the tension to 40 N / m, with a taper of 70% and a corner of 25%.

[0422] The film thickness was measured at 1,612 locations using an inline retardation / film thickness measuring device RE-200L2T-Rth+film thickness (manufactured by Otsuka Electronics Co., Ltd.), and the difference in height between the highest and lowest points of the uneven structure formed on the film surface was calculated and used as the average value. At this time, the traverse movement speed was 100 mm / sec.

[0423] Film roll No. 1 was produced through the above steps.

[0424] [A.2 Preparation of film rolls No. 2 to 13] Film rolls Nos. 2 to 13 were produced in the same manner as film roll No. 1, except that the type of film-forming dope (resin composition) in the dope preparation step [S1], the winding length [m], winding speed [m / min], film thickness [μm], touch pressure [N / m] and tension [N / m] at the periphery of the winding core during winding, touch pressure [N / m] and tension [N / m] at the center of the winding, and touch pressure [N / m] and tension [N / m] at the outer periphery of the winding were changed as shown in Table I.

[0425] [Table 1]

[0426] [B. Calculation of the thickness of the void layer around the core, the center of the winding, and the outer periphery of the winding] After storing each film roll at 40°C and 80% RH for one week, the thickness of the void layer around the core, in the center of the roll, and around the outer periphery of the roll was calculated using the method described above (an example of a method for calculating the thickness of the void layer).

[0427] The specific method for calculating the thickness of the void layer around the core using film roll No. 1 is shown below.

[0428] After one week of storage, the position of the film roll No. 1 at the side in the width direction, which is 20% of the winding diameter (P 20 The side surface was photographed with the center at the center, the image data was obtained, and edge enhancement processing was performed on the obtained image data to obtain a processed image for calculating the thickness of the void layer as shown in Figure 5.

[0429] Then, the center of the processed image (P 20 The radial length was measured starting from the point at which the film was wound, perpendicular to the film surface, and ending at the point at the 100th layer toward the outside of the winding. The thickness X [μm] of the void layer around the winding core was calculated using the following formula (A).

[0430] Formula (A) Thickness of void layer X [μm] = [radial length [μm] - (average thickness per film layer measured with a film thickness meter [μm]) × (number of layers)] ÷ (number of layers)

[0431] Substituting the measured values, the thickness of the void layer of film roll No. 1, X [μm] = [4020 μm - 40.00 μm × 100] ÷ 100 = 0.20 μm.

[0432] The thickness of the void layer at the center of the winding is determined at the position where the winding diameter is 50% on the side in the width direction (P 50 ) as the center, and photograph the side surface. 50 ) was used as the starting point, the thickness of the void layer in the peripheral portion of the winding core was calculated in the same manner.

[0433] The thickness of the void layer at the outer periphery of the winding is determined at the position where the winding diameter is 80% on the side in the width direction (P 80 ) as the center, and photograph the side surface. 80 ) was used as the starting point, the thickness of the void layer in the peripheral portion of the winding core was calculated in the same manner.

[0434] [Rating C] [C.1 Evaluation based on the amount of winding misalignment] (Evaluation method) After one week of storage, each film roll was placed in the transport environment recorder "Toughroger TR-1000" (manufactured by IMV Corporation) and subjected to a vibration test at 5.8 m / s across the width of the film roll. 2 The amount of deviation between the left and right edges of the film roll in the width direction was measured and evaluated based on the following criteria. The results are shown in Table I.

[0435] The "left and right deviation amount" will be explained below. FIG. 19 is a conceptual diagram showing the amount of left-right misalignment of the end faces in the width direction of the film roll as viewed from a direction perpendicular to the width direction of the film roll.

[0436] Before the vibration test, the end faces of the film roll (30) in the width direction are not shifted to the left or right, and the end faces at this time are the shortest end faces (S S )

[0437] In addition, as a result of the vibration test on the film roll, misalignment occurred on each end face of the film roll as shown in Figure 19. The end face where the largest misalignment occurred was the longest end face in the width direction of the film roll (S L )

[0438] The shortest end face (S S ) and the longest end of the film roll in the width direction (S L The length of the shift in the width direction between the end face of the film roll and the end face of the film roll was defined as the "amount of shift between the left and right sides of the end face of the film roll in the width direction."

[0439] (Evaluation criteria) ○: The amount of deviation was less than 2 mm. △: The amount of misalignment was 2 mm or more and less than 10 mm. ×: The amount of deviation was 10 mm or more.

[0440] [C.2 Evaluation based on the degree of sticking failure during long-term storage] (Evaluation method) Each of the film rolls was stored in a warehouse at room temperature for one month, after which the film was partially unwound from each film roll, and the condition of the film and film roll was visually observed and evaluated based on the following evaluation criteria. The results are shown in Table I.

[0441] (Evaluation criteria) ⊚: No adhesion of films to each other, no changes such as wrinkles or deformations. Good: The films were slightly stuck together and slight wrinkles were observed on the surface of the film roll, but no deformation was observed. Δ: The films were stuck together, wrinkles were observed on the surface of the film roll, and some deformation was observed, but this was not a problem in practical use. ×: The films were strongly stuck together, strong wrinkles were observed from the surface to the inside of the film roll, and strong deformation was observed on the surface of the film roll, extending to the inside.

[0442] [D Summary] As is clear from the conditions and evaluation results shown in Table I, the examples of the present invention showed no misalignment during the vibration test compared to the comparative examples, and no sticking problems even during long-term storage. [Explanation of symbols]

[0443] 1, 1a Stirring device (stirring tank) 2 Casting die 3 Support (endless belt, drum) 3a, 3b rollers 4 Peeling roller 5 Casting membrane 6 Drying equipment 7. Stretching device (tenter stretching device, diagonal stretching device) 8 Cut section 9 Stretching device (tenter stretching device) 10 Cut section 11 Drying equipment 12 Cut section 13 Winding device 14 Extruder 15 Casting die 16 Cast drum, support 16a Touch Roller 17 Cooling drum 19 Stretching device (tenter stretching device) 20 Cut section 21 Stretching device (tenter stretching device) 22 Cut section 23 Winding device 30 film rolls 31 Film 32 Roller 33 Touch Roller 40 Stretching device (tenter stretching device) 42 clips 46 Cover 48 endless chain 50 driving sprocket 52 driven sprocket 54 Rail 56 Opening member 60 Total Reflection Mirror 61 Half Mirror 62 Telecentric Lens 63 High-brightness line lighting 64 Monochrome line sensor camera 80 Temperature distribution sensor 101 Nozzle fixing part 102 nozzle 103 Casting membrane 104 End nozzle 105 Central nozzle 106 Clip Cover 200 LCD display device 210 First polarizing plate 211 Polarizing plate protective film arranged on the surface of the first polarizer opposite to the liquid crystal cell side 212 First polarizer 213 Polarizing plate protective film arranged on the liquid crystal cell side of the first polarizer 220 Liquid Crystal Cell 230 Second polarizing plate 231 Polarizing plate protective film arranged on the liquid crystal cell side of the second polarizer 232 Second Polarizer 233 Polarizing plate protective film arranged on the surface of the second polarizer opposite to the liquid crystal cell side 240 Backlight A. Periphery of the core B Center of winding C Outer periphery of winding F film F in Film close to the core F out Film near the outside of the roll L1: The film layer wound on the outside of the film closest to the core L2: The film layer wound on the outer side of the film closer to the outer side of the winding H A , H B width Q Thermocouple, Infrared (IR) Heater E. Imaging device R winding core Width direction of TD film roll U Imaging unit P Any point on the side of the film roll in the width direction S: Measurement surface of film roll (side surface in width direction) S0 core surface S1: Layer of film attached to the surface of the core S2: The film layer that forms the boundary between the periphery of the core and the center of the core S3: The film layer that forms the boundary between the center of the winding and the outer periphery of the winding The outermost film layer of an S4 film roll S L The longest edge of the film roll in the width direction S S The shortest end face of the film roll in the width direction P 20 Position where the winding diameter is 20% P 50 Position where the winding diameter is 50% P 80Position where the winding diameter is 80%

Claims

1. A film roll having no knurled portion, When the thickness of the gap layer between adjacent films in the peripheral portion of the winding core measured at the side portion in the width direction of the film roll is X [μm] and the thickness of the gap layer between adjacent films in the outer peripheral portion of the winding is Y [μm], X and Y satisfy the relationship of the following formula (1), The X [μm] and the Y [μm] satisfy the following formulas (2) and (3): A film roll characterized by: Formula (1) X<Y Formula (2) 0.15<X<0.40 Formula (3) 1<(Y / X)≦3

2. A method for manufacturing a film roll that does not have a knurled portion, When the thickness of the gap layer between adjacent films in the peripheral portion of the winding core measured at the side portion in the width direction of the film roll is X [μm] and the thickness of the gap layer between adjacent films in the outer peripheral portion of the winding is Y [μm], X and Y satisfy the relationship of the following formula (1), The X [μm] and the Y [μm] are adjusted so as to satisfy the following formulas (2) and (3): A method for producing a film roll, comprising: Formula (1) X<Y Formula (2) 0.15<X<0.40 Formula (3) 1<(Y / X)≦3

3. The film touch pressure at the peripheral portion of the core is adjusted within a range of 6 to 55 [N / m], the film touch pressure at the center of the winding is adjusted within a range of 4 to 40 [N / m], and the film touch pressure at the outer peripheral portion of the winding is adjusted within a range of 3 to 30 [N / m]. The method for producing a film roll according to claim 2 .

4. A part of the film of the film roll according to claim 1 is provided A polarizing plate characterized by:

5. A part of the film of the film roll according to claim 1 is provided A display device characterized by:

Images