CN117126503A

CN117126503A - Film roll, method for producing the same, polarizing plate, and display device

Info

Publication number: CN117126503A
Application number: CN202310589346.9A
Authority: CN
Inventors: 尾山真也; 增田修; 金子由纪; 南条崇
Original assignee: Konica Minolta Inc
Current assignee: Konica Minolta Inc
Priority date: 2022-05-25
Filing date: 2023-05-24
Publication date: 2023-11-28
Also published as: TW202406821A; KR20230164560A; JP2023173151A

Abstract

[ problem ] the technical problem of the present invention is: provided are a film roll, a method for producing the same, a polarizing plate, and a display device, wherein no adhesive tape transfer mark remains, and chain-like film deformation caused by air escape during long-term storage does not occur. [ solution ] to provide a film roll having no knurled portion, wherein when the thickness of a gap layer between films adjacent to each other in the peripheral portion of a roll core measured on the side surface portion in the width direction of the film roll is X [ mu ] m and the thickness of a gap layer between films adjacent to each other in the peripheral portion of the roll is Y [ mu ] m, the X and the Y satisfy the following formula (1) in the relation of formula (1): y < X.

Description

Film roll, method for producing the same, polarizing plate, and display device

Technical Field

The invention relates to a film roll, a method for manufacturing the same, a polarizing plate and a display device. More specifically, the present invention relates to a film roll or the like in which no tape transfer mark remains, and chain-like film deformation due to air escape during long-term storage does not occur.

Background

In recent years, with the intense price competition of liquid crystal televisions, cost reduction measures such as reduction of a change loss have been studied by polarizer manufacturers, and in order to cope with the measures, film growth for polarizers has been advanced.

By lengthening the film, cost reduction can be expected from various viewpoints such as connection loss, inspection man-hours, transportation, auxiliary materials, and the like, and the film is generally wound into a roll after production from the viewpoint of convenience in storage and transportation.

However, in particular, if a film roll formed by winding a film in a long form is stored for a long period of time, there is a problem in that: when the films are unwound, a tape transfer trace (hereinafter also referred to as "tape transfer") due to the adhesion of the films to each other remains, and a chain-like film deformation (hereinafter also referred to as "chain-like deformation") is caused by the escape of air between the films.

The term "chain deformation" as used herein refers to deformation of a film (chain defect) caused by stress due to the self weight of the film after winding and stress to be extended in the width direction of the film.

As a means for solving the above-mentioned problems, a means of winding together with the protective film is considered, but there is a problem that the protective film becomes waste.

As means for solving the above problems without discharging waste, the following means can be considered: the end portions of the films are subjected to a knurling process in advance, and air is introduced between the films during winding, whereby a void layer (also referred to as an "air layer") having an appropriate thickness is formed, and adhesion of the films to each other is suppressed.

However, the knurling process has a problem that the effect of suppressing adhesion is weaker than that of the wrapping process with the protective film.

Further, by using the above means, the pressure applied to the surface of the film increases as the film approaches the winding core of the film roll, and the air between the films is easily released, so that the void layer becomes thin, and there is a problem that the adhesive tape transfer trace caused by the adhesion of the films wound around the portion near the winding core and the chain-like deformation caused by the air release between the films when the film roll is stored for a long period of time are caused.

Patent document 1 discloses the following method: when the film is wound, the amount of air that enters between the films is made constant by changing the magnitude of the winding tension and the height of the knurling on the end of the film in accordance with the winding diameter of the film roll, and an air layer of an appropriate thickness is formed.

In the present specification, the "void layer" refers to a layer formed by a gap between facing surfaces of adjacent films in a film roll, and refers to a layer in which air or a substance other than air (for example, a gas such as an inert gas) can be present. The layer composed of air in the "void layer" is strictly referred to as an "air layer", but the "air layer" is referred to as a "void layer" unless the two are distinguished from each other, and the present invention is not particularly affected. "

Further, the mode in which fine concave-convex shaped protrusions inherent to films existing on one film surface of adjacent films are in contact with the other film surface facing each other everywhere is also one mode of the void layer. In the present invention, the void layer formed by embossing (concave-convex shape) artificially imparted to the film by the knurling is not included.

Prior art literature

Patent literature

[ patent document 1] Japanese patent application laid-open No. 2013-46966

Disclosure of Invention

Technical problem to be solved by the invention

The present invention has been made in view of the above problems and conditions, and solves the technical problems: provided are a film roll, a method for producing the same, a polarizing plate, and a display device, wherein no adhesive tape transfer mark remains, and chain-like film deformation caused by air escape during long-term storage does not occur.

Technical means for solving the problems

The present inventors have studied the cause of the above-mentioned problems and have found that the above-mentioned problems can be solved by making the thickness of the void layer between the films at the peripheral portion of the winding core thicker than the thickness of the void layer at the peripheral portion of the winding core without knurling the film winding, and have completed the present invention.

That is, the technical problem of the present invention is solved by the following means.

1. A film roll having no knurled portion, wherein X and Y satisfy the relationship of the following formula (1) when X [ mu ] m is the thickness of a gap layer between films adjacent to each other in the peripheral portion of a roll core measured on the side surface portion in the width direction of the film roll and Y [ mu ] m is the thickness of a gap layer between films adjacent to each other in the peripheral portion of the roll,

formula (1): y < X.

2. The film roll according to claim 1, wherein the X [ μm ] and the Y [ μm ] satisfy the following formula (2) and the following formula (3),

formula (2): 0.05< Y <0.50

Formula (3): 1< (X/Y) <3.

3. A method for producing a film roll which is a film roll having no knurled portion, wherein, when the thickness of a gap layer between films adjacent to each other in the peripheral portion of the roll core measured on the side surface portion in the width direction of the film roll is X [ mu ] m and the thickness of a gap layer between films adjacent to each other in the peripheral portion of the roll is Y [ mu ] m, the thickness is adjusted so that the X and the Y satisfy the relation of the following formula (1),

formula (1): y < X.

4. The method for producing a film roll according to claim 3, wherein the film roll is adjusted so that the X [ μm ] and the Y [ μm ] satisfy the following formula (2) and the following formula (3),

Formula (2): 0.05< Y <0.50

Formula (3): 1< (X/Y) <3.

5. The method for producing a film roll according to item 3 or 4, wherein the film touch pressure at the peripheral portion of the roll core is adjusted to a range of 2 to 30[ n/m ], the film touch pressure at the central portion of the roll is adjusted to a range of 3 to 40[ n/m ], and the film touch pressure at the peripheral portion of the roll is adjusted to a range of 5 to 55[ n/m ].

6. A polarizing plate is provided with: a portion of the film roll of item 1 or item 2.

7. A display device is provided with: a portion of the film roll of item 1 or item 2.

Effects of the invention

By the means of the present invention, it is possible to provide: film roll free from adhesive tape transfer marks and chain-like film deformation due to air escape during long-term storage, and its manufacturing method, polarizing plate and display device.

The expression mechanism or action mechanism of the effect of the present invention is not clear, but is presumed as follows.

The film roll of the present invention is configured such that the thickness of the void layer between films in the peripheral portion of the roll core is thicker than the thickness of the void layer in the peripheral portion of the roll core without knurling, and thus, no tape transfer mark due to adhesion of films to each other remains, and chain-like film deformation (hereinafter also referred to as "chain-like deformation") due to air escape between films can be prevented.

As described above, the term "chain deformation" refers to deformation of the film (chain defect) caused by stress due to the self weight of the film after winding and stress to be extended in the width direction of the film.

If the film roll is knurled as in the prior art to increase the amount of air that enters between the films, the gap layer between the films becomes thicker than if the process was not performed.

When the film roll is stored for a long period of time, the radial stress of the film is applied more to the portion closer to the roll core due to the dead weight of the film or the like, and particularly when the film roll generates a minute impact, the radial stress is applied more.

When radial stress of the films is applied, air between the films escapes, and therefore, the film roll subjected to the knurling becomes larger in the thickness change of the void layer in the portion close to the roll core than that of a normal film roll, and adhesion of the films to each other is particularly likely to occur in the roll core portion, and a large amount of tape transfer marks due to adhesion of the films to each other remain in the roll core portion.

Further, since the film roll subjected to the knurling is supported only by the embossed portion, a restriction force for preventing winding displacement is applied to the embossed portion, and since the stress applied to the film is uneven, the amount of air escaping between the films is uneven, and the thickness of the void layer becomes uneven, chain-like deformation is likely to occur during long-term storage.

In contrast, the film roll of the present invention has no embossed portion, and the film is supported by a minute contact surface between the films or the whole body of the gas (for example, air) in the void layer, so that the restraining force for preventing the winding displacement does not deviate, and the stress applied to the film becomes uniform.

In more detail, although the film roll of the present invention is not knurled, since the film surface generally has voids formed by fine concave-convex shapes of nanometer dimensions inherent to the film, there is a possibility that the film is supported by the entirety of the fine contact surfaces of the convex portions when the convex portions of the facing surfaces of adjacent films are in contact with each other everywhere.

That is, for example, since a part of the convex portion is in contact with each other, the films are supported not only by the void layer such as the air layer but also by a plurality of contact points formed by the minute irregularities.

Further, it is presumed that by thickening the void layer for allowing an appropriate amount of air to enter in the core portion, the thickness unevenness of the void layer in the whole film roll can be suppressed to be small even if more air escapes in the core portion during long-term storage of the film roll, and the void layer of uniform thickness can be formed between films, whereby no tape transfer mark remains and no chain-like deformation occurs when the film of the film roll is unwound.

Drawings

FIG. 1 is a schematic view showing a positional relationship between a side surface portion in the width direction of a film roll and an imaging device

FIG. 2 is a schematic view of the widthwise side surface portion of the film roll when viewed from a plane perpendicular to the side surface portion

FIG. 3A processed image for calculating the thickness of a void layer

FIG. 4 is a schematic conceptual view for explaining a part of the widthwise side portions of the film roll in the peripheral portion of the roll core, the roll center portion and the roll outer peripheral portion

FIG. 5 is a schematic view of the internal structure of the photographing unit

FIG. 6 is a schematic diagram of the system configuration of the imaging device

FIG. 7 is a flow chart showing a flow of a production process by a solution casting film forming method

FIG. 8 is a schematic view of an apparatus for producing a film by a solution casting film-forming method

FIG. 9 is a schematic plan view showing the internal structure of a tenter stretching device

FIG. 10 is a plan view showing a state in which the cover of the tenter stretching device is removed

FIG. 11 is a schematic view of the nozzle and heater arrangement portion when the 3 zones in the stretching apparatus of the tenter are seen from the front

FIG. 12 side view of 3 zones within a tenter frame stretching apparatus

FIG. 13 is a schematic view showing a step of winding a film and a cross section of a film roll of the present invention after winding

FIG. 14 is a flowchart showing a flow of a production process by a melt-casting film-forming method

FIG. 15 is a schematic view of an apparatus for producing a film by a melt-casting film-forming method

FIG. 16 is a schematic view showing an example of the constitution of a liquid crystal display device of the present invention

Detailed Description

The film roll of the present invention is a film roll having no knurled portion, wherein X and Y satisfy the relation of formula (1) when X [ mu ] m is the thickness of the gap layer between films adjacent to each other in the peripheral portion of the roll core measured on the side surface portion in the width direction of the film roll and Y [ mu ] m is the thickness of the gap layer between films adjacent to each other in the peripheral portion of the roll.

Through the above features, the technical problems of the present invention can be solved.

The method for producing a film roll according to the present invention is a method for producing a film roll having no knurled portion, wherein the thickness of the gap layer between films adjacent to each other in the peripheral portion of the roll core measured on the side surface portion in the width direction of the film roll is X [ mu ] m, and the thickness of the gap layer between films adjacent to each other in the peripheral portion of the roll is Y [ mu ] m, and wherein the thickness of the gap layer between films adjacent to each other in the peripheral portion of the roll is adjusted so that the X and the Y satisfy the relation of the formula (1).

The above two features are features of the technology common to or corresponding to the following embodiments (modes).

In an embodiment of the present application, from the viewpoint of uniform void layer formation during long-term storage, it is preferable that the X [ μm ] and the Y [ μm ] satisfy the formula (2) and the formula (3).

From the viewpoint of uniform void layer formation during long-term storage, it is preferable to adjust the conditions so that the X [ mu ] m and the Y [ mu ] m satisfy the formulas (2) and (3).

From the viewpoint of uniform void layer formation during long-term storage, it is preferable to adjust the film touch pressure in the peripheral portion of the winding core to a range of 2 to 30[ N/m ], to adjust the film touch pressure in the central portion of the winding to a range of 3 to 40[ N/m ], and to adjust the film touch pressure in the peripheral portion of the winding to a range of 5 to 55[ N/m ].

A part of the film roll of the present application can be suitably used by being provided in a polarizing plate.

A part of the film roll of the present application can be suitably used by being provided in a display device.

The present application and its constituent elements, and specific embodiments and modes of the present application will be described in detail below. In the present application, "to" is used in a sense of including the numerical values described before and after the "to" as the lower limit value and the upper limit value.

1. Film roll

(1.1) outline of film roll

The film roll of the present invention is a film roll having no knurled portion, wherein X and Y satisfy the relationship of the following formula (1) when X [ mu ] m is the thickness of a gap layer between films adjacent to each other in the peripheral portion of a roll core measured on the side surface portion in the width direction of the film roll and Y [ mu ] m is the thickness of a gap layer between films adjacent to each other in the peripheral portion of the roll.

Formula (1): y < X

In the film roll (film roll "means a film wound in a roll shape) of the present invention, since the film is entirely supported by gas (e.g., air) in a gap between adjacent films or a minute contact surface between films as described above, the stress applied to the film becomes uniform without deviation of the restricting force for preventing the winding deviation, in the portion where the knurling (also referred to as" embossing ") is not performed.

Further, by thickening the void layer in the core portion in an amount for allowing an appropriate amount of air to enter, it is possible to suppress the variation in the thickness of the void layer in the whole film roll to be small even if more air escapes from the core portion during long-term storage of the film roll, and to form a uniform void layer between films, whereby no adhesive tape transfer mark remains and no chain-like deformation occurs when the film of the film roll is unwound.

In an embodiment of the present invention, from the viewpoint of uniform void layer formation during long-term storage, it is preferable that the X [ μm ] and the Y [ μm ] satisfy the formula (2) and the formula (3).

(1.2) interstitial layers between films

(1.2.1) means for controlling the thickness of the void layer

The film roll of the present invention can suppress the variation in thickness of the void layer in the whole film roll to be small and form a uniform void layer between films even when the film roll is stored for a long period of time, particularly even if more air escapes from the roll core portion, by thickening the void layer for allowing an appropriate amount of air to enter the roll core portion.

Examples of such means include means for changing the film touch pressure by a touch roller, means for changing the winding tension, winding speed, and roller inclination angle.

The number of the touch rolls may be plural, or may be chrome-plated as a surface treatment.

Further, the touch roller may use an elastic roller or the like.

(1.2.2) method for calculating thickness of void layer

Fig. 1 is a schematic diagram showing a positional relationship between a side surface portion in the width direction of a film roll and an imaging device.

As shown in fig. 1, the imaging device (E) is provided on the side surface of the film roll (30) wound around the winding core (R) in the width direction.

In fig. 1, TD is the width direction of the film roll.

An example of an imaging method based on the side surface portion in the width direction of the film roll of the imaging device and a method for calculating the thickness of the void layer will be described below.

The image data for calculating the gap between films is acquired by photographing the side surface portion of the film roll in the width direction with an arbitrary point (P) on the side surface portion of the film roll in the width direction as a center by a photographing unit (U) which is a part of the photographing device.

Fig. 2 is a schematic view of the side surface portion in the width direction of the film roll when viewed from a surface perpendicular to the side surface portion.

Here, as shown in fig. 2, when the surface of the secondary winding core (S ₀ ) To the outermost film layer of the film roll (S ₄ ) When the roll diameter is expressed as a percentage, the surface of the core (S ₀ ) The roll diameter of the film roll was 0%, and the outermost film layer (S ₄ ) The roll diameter of (2) is 100%.

When photographing the periphery of the winding core, the position (P) with the winding diameter of 20 percent is adopted ₂₀ ) The image data is obtained by photographing the side surface portion as a center.

When the center portion of the roll was photographed, the position (P) was set at a position where the roll diameter was 50% ₅₀ ) The side surface portion was photographed at a position (P) of 80% of the roll diameter when photographing the outer peripheral portion of the roll ₈₀ ) The image data is acquired by photographing the side surface portion as a center.

Then, edge emphasis processing is performed on the acquired image data to obtain a processed image for calculating the thickness of the void layer as shown in fig. 3, and the thicknesses of the void layers between adjacent films in the core peripheral portion, the roll center portion, and the roll outer peripheral portion of the side portion in the width direction of the film roll are calculated.

Since the thickness of the gap layer between films is calculated in 3 areas, i.e., the core peripheral portion, the roll center portion, and the roll outer peripheral portion, before specific examples for calculating the thickness of the gap layer are performed, first, the concept of 3 areas, i.e., the core peripheral portion, the roll center portion, and the roll outer peripheral portion, will be described.

Fig. 4 is a schematic conceptual diagram for explaining a part of the widthwise side surface portion of the film roll in the roll core peripheral portion, the roll center portion, and the roll outer peripheral portion.

In FIG. 4, when the winding material is directly wound around the winding core (R) and attached to the surface of the winding core (S ₀ ) The layer of the film (not shown) is S ₁ The outermost layer of the film roll is set as S ₄ At the time, will follow S ₁ To S ₄ When the region of the roll core is divided into 3 equal regions, the region on the roll core side is defined as a roll core peripheral portion (a), the region on the outside of the roll is defined as a roll outer peripheral portion (C), and the region between the roll core peripheral portion (a) and the roll outer peripheral portion (C) is defined as a roll center portion (B).

The layer of the film that forms the boundary between the core peripheral portion (A) and the core central portion (B) is S ₂ The layer of the film which becomes the boundary between the roll center portion (B) and the roll outer peripheral portion (C) is S ₃ 。

Specific examples of the method for calculating the thickness of the void layer in the peripheral portion of the roll include the following calculation methods.

(specific example of a method for calculating the thickness of the void layer)

For example, in calculating the thickness of the void layer at the periphery of the winding core, the position (P ₂₀ ) The image data for calculating the gap between films is obtained by capturing the side surface portion of the film roll in the width direction as the center, and then the edge emphasis processing is performed on the obtained image data to obtain a processed image as shown in fig. 3, and the center (P ₂₀ ) The radial length was measured from the point located at the 100 th layer position perpendicular to the film surface toward the outside of the roll as the starting point, and the thickness X [ mu ] m of the void layer was calculated using the following formula (A)]。

The thickness X [ μm ] = [ length in radial direction [ μm ] - (average thickness [ μm ] X (number of layers) per 1 layer of the film layer measured by a film thickness meter) ]

The (number of layers) in the above formula is determined by whether the end point is located at the second layer toward the winding outer side perpendicular to the film surface, and when the end point is located at the 100 th layer as described above, (number of layers) =100.

In the calculation of the thickness of the void layer in the winding center portion, the position (P ₂₀ ) Change to position (P) ₅₀ ) The calculation was performed in the same manner as described above, except that the position (P ₂₀ ) Change to position (P) ₈₀ ) The calculation was performed in the same manner as described above.

Since the total length of the film roll is short, when the film roll is imaged on the side surface portion in the width direction around the arbitrary point (P), if there is no 100 layers facing the outside of the roll perpendicularly to the film surface, for example, if there are only 70 layers, the radial length may be measured with the point located at the 70 th layer as the end point, and the thickness X [ μm ] of the void layer may be calculated using the above formula (a).

As the film thickness meter in the above formula (a), for example, serial phase retardation (doctor solution) film thickness measuring device RE-200L 2T-rth+film thickness (manufactured by otsukaeleectronics corporation) may be used.

(System configuration of shooting Unit and shooting device)

As the photographing unit, the following configuration is used.

Fig. 5 is a schematic diagram of the internal structure of the imaging unit (U), and S in fig. 5 is the surface to be measured (broadside direction side surface portion) of the film roll. The main constituent elements in fig. 5 are as follows.

Constituent parts-

Quan Fanshe mirror (60)

Half mirror (61)

Telecentric lens (62) (MML 1-HR130VI-35F: manufactured by MORITEX Co., ltd.; magnification. Times.1, WD130 mm)

High brightness line illumination (63) (LNSP 2-100SW: manufactured by CCS Co., ltd.)

Monochromatic line sensor-camera (64) (RMSL 8K39CL 8000 pixels of 3.5 μm/pixel manufactured by Japanese electronics, inc.)

The system configuration of the imaging device is shown in a schematic diagram in fig. 6.

2. Method for manufacturing film roll

The film roll manufacturing method of the present invention is a film roll manufacturing method for manufacturing a film roll having no knurled portion, wherein when the thickness of a gap layer between films adjacent to each other in a peripheral portion of a roll core measured on a side surface portion in a widthwise direction of the film roll is X [ mu ] m, and the thickness of a gap layer between films adjacent to each other in an outer peripheral portion of the roll is Y [ mu ] m, the thickness is adjusted so that the X and the Y satisfy the relation of the formula (1).

In the method for producing a film roll, from the viewpoint of formation of a uniform void layer during long-term storage, it is preferable to adjust the thickness so that the thickness of the film roll X [ μm ] and the thickness of the film roll Y [ μm ] satisfy the formulas (2) and (3).

In addition, from the viewpoint of formation of a uniform air layer during long-term storage, it is preferable that the film touch pressure in the peripheral portion of the winding core is adjusted to a range of 2 to 30[ N/m ], the film touch pressure in the central portion of the winding is adjusted to a range of 3 to 40[ N/m ], and the film touch pressure in the peripheral portion of the winding is adjusted to a range of 5 to 55[ N/m ].

The film roll of the present invention can be produced by using a usual production method such as a blow-up method, a T-die method, a calendaring method, a cutting method, a casting method, an emulsion method, or a hot press method, and a solution casting film-forming method and a melt casting film-forming method are preferable from the viewpoints of suppression of coloring, suppression of defects of foreign matters, suppression of optical defects of die lines, and the like, and a solution casting film-forming method is particularly preferable from the viewpoint of uniformity of the film surface.

(2.1) solution casting film-making method

Fig. 7 is a flowchart showing a flow of a process for producing a solution casting film forming method, and fig. 8 is a schematic diagram of an apparatus for producing a film by a solution casting film forming method.

The following solution casting film forming method will be described with reference to fig. 7 and 8.

The method for producing a film by a solution casting film formation method comprises: a dope producing step [ S1], a casting step [ S2], a peeling step [ S3], a shrinking step [ S4], a 1 st drying step [ S5], a 1 st stretching step [ S6], a 1 st cutting step [ S7], a 2 nd stretching step [ S8], a 2 nd cutting step [ S9], a 2 nd drying step [ S10], a 3 rd cutting step [ S11], and a winding step [ S12].

The production method does not need to include both the 1 st drying step [ S5] and the 2 nd drying step [ S10], and may include at least any one step.

Further, the stretching step 1 [ S6], the stretching step 2 [ S8], and any one of the cutting steps 1 [ S7], 2 [ S9] and 3 [ S11] may be included.

(2.1.1) Process for preparing (stirring preparation) of dope [ S1]

Hereinafter, as an embodiment of the present invention, the dope production process will be described by taking a case where cycloolefin resin (hereinafter, also referred to as "COP") is used as a thermoplastic resin as an example, and the present invention is not limited thereto.

In the dope preparation (stirring preparation) step [ S1] of fig. 7, at least the resin and the solvent are stirred in the stirring tank (1 a) of the stirring apparatus (1) of fig. 8, and the dope cast on the support (3) (endless belt) is prepared.

(solvent)

As the solvent, a mixed solvent of a good solvent and a poor solvent is used.

The present step is a step of dissolving the COP and, if necessary, other compounds in a solvent mainly containing a good solvent for the COP in a dissolution vessel while stirring to form a dope, or a step of mixing, if necessary, other compound solutions in the COP solution to form a dope as a main dissolution solution.

From the viewpoint of reducing the drying load after casting the dope onto the support, it is preferable that the higher the concentration of COP in the dope is, but if the concentration is too high, the load at the time of filtering the dope is increased, and the accuracy is deteriorated, so that it is necessary to combine the reduction of the drying load and the load suppression at the time of filtering.

In order to achieve these effects, the concentration of COP in the dopant is preferably in the range of 10 to 35 mass%, more preferably in the range of 15 to 30 mass%.

The dopant preferably contains water in an amount of 0.01 to 2 mass%.

The solvent used for the dope may be used alone or in combination of two or more, and from the viewpoint of productivity, it is preferable to use a good solvent and a poor solvent for COP in combination, and from the viewpoint of solubility of COP, it is preferable that the good solvent is more.

The preferable range of the mixing ratio of the good solvent and the poor solvent is 70 to 98 mass% and the poor solvent is 2 to 30 mass%.

In the present specification, the "good solvent" of COP is defined as COP used for dissolution alone, and the "poor solvent" of COP is defined as COP used for swelling alone or COP used for non-dissolution.

Therefore, the good solvent and the poor solvent vary according to the average substitution degree of the COP.

The good solvent used in the present invention is not particularly limited, and examples thereof include organic halogen compounds such as methylene chloride, dioxolanes, acetone, methyl acetate, methyl acetoacetate, and the like, and particularly preferred examples thereof include methylene chloride and methyl acetate.

The poor solvent used in the present invention is not particularly limited, and for example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone and the like are preferably used.

The solvent used for dissolving COP is recovered and reused by drying the solvent removed from the film in each step.

The recovery solvent may contain a small amount of an additive added to COP, for example, a plasticizer, an ultraviolet absorber, a resin, a monomer component, or the like, but if the solvent is contained, the solvent may be preferably recycled, and if necessary, may be purified and recycled.

(dissolution method)

As the method for dissolving COP in the preparation of the dope described above, a usual method can be used.

Specifically, a method performed under normal pressure, a method performed at a boiling point of the main solvent or less, a method performed by pressurizing at a boiling point of the main solvent or more are preferable, and when heating and pressurizing are combined, heating to a boiling point of the normal pressure or more is possible.

The method of stirring and dissolving the solvent at a temperature not lower than the boiling point of the solvent under normal pressure and within a range where the solvent does not boil under pressure is also preferable because it can prevent the formation of gels and lumps of undissolved substances called lumps of dough.

Further, a method of mixing COP with a poor solvent, wetting or swelling the mixture, and then further adding a good solvent to dissolve the mixture is also preferable.

The pressurization may be performed by a method of pressurizing an inert gas such as nitrogen or a method of increasing the vapor pressure of the solvent by heating.

The heating is preferably performed from the outside, for example, a jacket type is preferable because temperature control is easy.

From the viewpoint of solubility of COP, it is preferable that the heating temperature of the solvent to be added is high, but if the heating temperature is too high, the required pressure becomes large, and productivity becomes poor.

The heating temperature is preferably in the range of 30 to 120 ℃, more preferably in the range of 60 to 110 ℃, and even more preferably in the range of 70 to 105 ℃.

In addition, the pressure is adjusted so that the solvent does not boil at the set temperature.

Alternatively, a cooling dissolution method is preferably used, whereby COP can be dissolved in a solvent such as methyl acetate.

(filtration)

Next, the COP solution (dope in solution or after dissolution) is preferably filtered using an appropriate filter material such as filter paper.

As the filter material, it is preferable that the absolute filtration accuracy is small in order to remove insoluble matters or the like, but if the absolute filtration accuracy is too small, clogging of the filter material is likely to occur.

Therefore, a filter having an absolute filtration accuracy of 0.008mm or less is preferable, a filter having a thickness of 0.001 to 0.008mm is more preferable, and a filter having a thickness of 0.003 to 0.006mm is still more preferable.

The material of the filter material is not particularly limited, and a filter material made of plastic such as polypropylene or TEFLON (registered trademark) or a filter material made of metal such as stainless steel is preferably used because no fiber is removed.

It is preferable to remove and reduce impurities contained in COP of the raw material, particularly, bright point foreign matter by filtration.

The spot foreign matter means a spot (foreign matter) where 2 polarizers are arranged in an orthogonal Nicole state, a film or the like is placed therebetween, light is irradiated from one polarizer side, and light from the opposite side appears to leak when viewed from the other polarizer side, and the number of spots having a diameter of 0.01mm or more is preferably 200 spots/cm ² The following is given.

More preferably 100/cm ² Hereinafter, more preferably 50/m ² Hereinafter, it is more preferably 0 to 10 pieces/cm ² The following is given.

In addition, the number of bright spots of 0.01mm or less is preferably small.

The filtration of the dope may be carried out by a usual method, and in a method of filtering while heating at a temperature not lower than the boiling point of the solvent under normal pressure and within a range where the solvent does not boil under pressure, it is preferable that the increase in the difference between the filtration pressure before and after filtration (referred to as differential pressure) is small.

The temperature is preferably in the range of 30 to 120 ℃, more preferably in the range of 45 to 70 ℃, and even more preferably in the range of 45 to 55 ℃.

The filtration pressure is preferably small.

Specifically, the pressure is preferably 1.6MPa or less, more preferably 1.2MPa or less, and still more preferably 1.0MPa or less.

(2.1.2) casting Process [ S2]

In the casting step [ S2] of fig. 7, the dope prepared in the dope preparation step [ S1] is fed to the casting die (2) of fig. 8 by a pressure type quantitative gear pump or the like, and the dope is cast from the casting die (2) at a casting position on a support (3) composed of a rotary-driven stainless steel endless belt which is infinitely transferred, thereby forming a casting film (5).

In this case, the inclination of the casting die (2), that is, the direction in which the dopant is discharged from the casting die (2) to the support (3), may be appropriately set so that the angle with respect to the normal line of the surface (the dope-casting surface) of the support (3) is in the range of 0 to 90 °.

Then, the casting film (5) is heated and dried on the support (3), and the solvent is evaporated until the casting film (5) can be peeled from the support (3) by the peeling roller (4).

In the present invention, the casting film refers to a dope film cast from the above lip portion.

The evaporation is preferably performed in an atmosphere in the range of 5 to 75 ℃.

In order to evaporate the solvent, there are a method of bringing warm air into contact with the upper surface of the casting film (5) and/or a method of conducting heat from the back surface of the support (3) by using a liquid, a method of conducting heat from the front surface back surface by using radiant heat, and the like, but a method of conducting heat from the front surface back surface by using radiant heat is preferable because the drying efficiency is good.

In addition, a method of combining them is also preferably used.

From the viewpoint of productivity, the width of casting (casting) is preferably 1.3m or more.

More preferably in the range of 1.3 to 4.0 m.

If the width of casting (casting) is not more than 4.0m, streaks are not added in the manufacturing process, and stability in the subsequent conveying process becomes high.

From the viewpoint of transportation and productivity, it is more preferably in the range of 1.3 to 3.0 m.

(casting die)

The casting mold is preferably a hanger type mold, a T type mold, or the like.

In order to improve the uniformity of the film thickness in the casting step, a method of controlling the slit gap (the front end opening of the slit nozzle liquid ejection port) of the lip portion (the portion where the dope of the casting die slit flows out) of the casting die in either the solution casting film forming method or the melt casting film forming method is known to those skilled in the art.

For example, when a dopant (including a melt) having a high viscosity is extruded, a deviation in the width of the slit gap occurs, but in order to prevent this, a method of controlling the slit gap by providing a plurality of heating bolts in the width is provided.

However, this method has a problem that the number of heating bolts has a physical setting limit.

In addition, there is a method of changing the internal structure of the casting die at the wide side in order to suppress the pressure fluctuation at the wide side that causes the variation in the wide side of the slit gap, but there is a problem in that it is necessary to change the casting die for each production type, and it takes time and costs.

The casting die is provided with a mechanism for adjusting a slit for discharging the dope (extrusion of the resin in the case of melting) to a wide side.

The initial discharge film thickness of the casting film is preferably controlled by adjusting the gap between the wide sides of the slit from which the dope is discharged to a range of 1.0 to 5.0% of the thickness deviation of the casting film immediately after discharge by the heating bolts of the casting die.

In order to increase the film forming speed of the film of the present invention, the support may be provided with 2 or more casting dies, and the number of dope may be divided into a plurality of layers.

Alternatively, it is also preferable to obtain a film roll of laminated structure by a co-casting method in which a plurality of dopants are cast simultaneously.

In order to increase the film forming speed, a plurality of casting dies may be provided on the support, and the number of dope may be divided into a plurality of layers.

(support)

The support (3) is preferably held by a pair of rolls (3 a), a roll (3 b) and a plurality of rolls located therebetween using a roll whose surface is subjected to plating finishing with, for example, a stainless steel belt or a cast.

In this case, the surface of the support is preferably a mirror surface.

One or both of the rollers (3 a) and (3 b) are provided with a driving device for imparting tension to the support body (3), whereby the support body (3) is used in a state of being tensioned by the application of tension.

The surface temperature of the support (3) in the casting step [ S2] is preferably a temperature in the range of-50℃to the boiling point of the solvent, since the drying rate of the casting film is high when the temperature is high.

The support temperature is preferably in the range of 0 to 55 ℃, more preferably in the range of 22 to 50 ℃.

The temperature of the support may be the same throughout, or may be different depending on the position.

The method for controlling the temperature of the support (3) is not particularly limited, and there are a method of blowing warm air or cool air and a method of bringing warm water into contact with the back surface side of the support.

Since heat can be transferred more efficiently by using warm water, it is preferable to shorten the time until the temperature of the support becomes constant.

When warm air is used, there are cases where air having a temperature higher than the target temperature is used.

(2.1.3) stripping step [ S3]

In this step, in the casting step [ S2], the solvent is evaporated on the support (3) until the casting film (5) reaches the peelable film strength, and after the film is dried and solidified or cooled and solidified, the film is peeled from the support (3) before the film winds around the support (3) for one week.

That is, the present step is a step of peeling the film obtained by evaporating the solvent on the support (3) at the peeling position.

In this case, from the viewpoint of the surface quality, moisture permeability, and peelability, the film is preferably peeled from the support within a range of 30 to 600 seconds.

In the peeling step (S3), the film is peeled off by a peeling roller (4) (a roller for facilitating peeling of the film) while maintaining self-supporting property.

The temperature of the peeling site on the support is preferably in the range of-50 to 40 ℃, more preferably in the range of 10 to 40 ℃, and most preferably in the range of 15 to 30 ℃.

(residual solvent amount)

The amount of the residual solvent in the film on the support (3) at the time of peeling in the peeling step [ S3] is appropriately adjusted depending on the strength of the drying condition, the length of the support (3), and the like, and the amount of the residual solvent in the shrinking step [ S4] is greatly affected by the thickness of the film, the resin, and the like, so that there is a range overlapping with the preferable range of the amount of the residual solvent in the peeling step [ S3] and the shrinking step [ S4 ].

The amount of residual solvent in the film also varies depending on the thickness of the film, but if the amount of residual solvent at the peeling point (the position where the film is peeled from the support) is too large, the film may be too soft to be peeled off, and the flatness may be impaired, or transverse segments, stripes, or longitudinal stripes may be easily generated due to peeling tension.

Conversely, if the amount of the residual solvent is too small, a part of the film may be peeled off in the middle.

From the above viewpoints, in order to achieve good flatness of the film, the amount of the residual solvent is preferably in the range of 10 to 50 mass% from the viewpoint of both economical speed and quality.

As a method for increasing the film forming speed (peeling is performed while the amount of residual solvent is as large as possible, and thus the film forming speed can be increased), there is a gel casting method (gel casting) in which peeling is possible even if the amount of residual solvent is large.

As the above method, there is a method of adding a poor solvent for COP to a dope and gelling a casting film after casting the dope; and a method in which the cast film is gelled by cooling the support and peeled off in a state where a large amount of residual solvent is contained.

In addition, there is a method of adding a metal salt to a dopant.

As described above, by forming the cast film into a gel on the support to reinforce the film, peeling of the film from the support can be accelerated, and the film forming speed can be increased.

The residual solvent amount is defined by the following formula.

The formula: residual solvent amount [ mass% ] = { (M-N)/N } ×100

In the above formula, M is the mass of a sample taken at any time during or after the production of a casting film or film, and N is the mass after M is heated at 115 ℃ for 1 hour.

(peel tension)

The peeling tension when peeling the support and the film is preferably 300N/m or less.

More preferably, the peeling is carried out at a tension of 190N/m or less when wrinkles are easily generated at the time of peeling in the range of 196 to 245N/m.

(2.1.4) shrinkage Process [ S4]

The shrinkage step [ S4] is a step of shrinking the film (F) in the width direction in the plane.

As a method for shrinking the film (F), for example, the following method can be used: a method of increasing the density of the film by performing a high-temperature treatment without maintaining the film in a wide-side state; a method in which tension is applied to the film peeled from the support in the transport direction (Machine Direction, hereinafter also referred to as "MD direction") and the film is stretched in the widthwise direction (TD direction) orthogonal to the MD direction in the film plane to shrink the film; and a method of sharply reducing the residual solvent amount of the film.

In this case, the film is shrunk in the widthwise direction (Traverse Direction, hereinafter also referred to as "TD direction") orthogonal to the MD direction in the film plane.

Since entanglement between resin molecules (matrix molecules) in the thickness direction of the film is promoted by the shrinkage step, even when the film is bonded to the polarizer via an adhesive in the production of a polarizing plate, for example, the adhesive is likely to penetrate into the film via entangled portions (crosslinked portions) 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 with respect to the polarizer can be improved.

That is, good adhesion between the film and the polarizer can be ensured.

(definition of shrinkage)

The shrinkage in the present invention is defined by the following formula.

The formula: shrinkage [% ] = width of film at the end of the shrinkage process [ mm ]/width of film at the beginning of the shrinkage process [ mm ] ×100

Here, in the shrinkage step [ S4], if the shrinkage of the film is too small, the effect of promoting entanglement between the matrix molecules becomes insufficient, and if it is too large, there is a risk that the production efficiency of the film (stretched film) is lowered.

Therefore, the shrinkage ratio of the film in the shrinkage step [ S4] is preferably in the range of 1 to 40%, more preferably in the range of 5 to 20%.

(method for measuring shrinkage and method for calculating shrinkage)

The width of the film was measured by LS-9000 manufactured by KEYENCE, inc.

The shrinkage of the film of the present invention is obtained by substituting the average value of the values obtained by measuring the film width by the measuring instrument for 5 minutes (300 seconds) every 1 second as the film width into the formula, but the shrinkage is not limited to the above method, and for example, a value obtained by reading the film width from a ruler may be used as the film width and substituted into the formula.

(2.1.5) 1 st drying step [ S5]

The 1 st drying step S5 is a step of heating the film F on the support by a drying device 6 to evaporate and dry the solvent.

In the drying apparatus (6) in fig. 8, the film (F) is conveyed by a plurality of conveying rollers arranged in a staggered manner when viewed from the side, and the film (F) is dried therebetween.

The drying method in the drying apparatus (6) is not particularly limited, and the film (F) is usually dried using hot air, infrared rays, a heating roller, microwaves, or the like, and from the viewpoint of simplicity, a method of drying the film (F) using hot air is preferable.

In addition, a method of combining them is also preferable.

The 1 st drying step [ S5] may be performed as needed.

If the film is not thick, the drying is rapid, but too rapid drying tends to impair the planarity of the finished film.

In the case of drying the film at a high temperature, it is necessary to consider the amount of the residual solvent before drying, but the residual solvent amount is not excessive, whereby failure due to foaming of the solvent can be prevented.

The amount of the residual solvent before the 1 st drying step [ S5] is preferably about 30% by mass or less, and the drying temperature is in the range of about 30 to 250 ℃ throughout the whole drying step.

The drying is particularly preferably carried out in the range from 35 to 200℃and the drying temperature is preferably increased stepwise.

In general, a roll drying method (a method in which a film is alternately passed through a plurality of rolls arranged vertically and dried) and a method in which a film is dried while being conveyed by a tenter method are used for drying the film.

In the case of using a tenter stretching device for drying a film, it is preferable to use a device capable of controlling the gripping length (the distance from the start of gripping to the end of gripping) of the film independently from left to right by left and right gripping mechanisms of the tenter stretching device in a stretching step to be described later.

In the stretching step, it is also preferable to intentionally create the partitions having different temperatures in order to improve the flatness.

Furthermore, it is also preferable to set the neutral region in such a way that the respective zones do not interfere between the different temperature zones.

(2.1.6) 1 st stretching step [ S6]

The 1 st stretching step [ S6] may be a step of stretching the film (F) in the MD direction only, a step of stretching the film in the TD direction only, a step of stretching the film in both the MD direction and the TD direction, or a step of stretching the film in an oblique direction.

The stretching direction is not limited, and from the viewpoint of obtaining a wide film, it is preferable to include a step of stretching in at least the width direction.

Such stretching is performed by a stretching device (7).

(stretching method)

Examples of the stretching method include a method of stretching (longitudinal stretching) by setting a circumferential speed difference of rolls in a conveying direction (longitudinal direction of a film; film forming direction; casting direction; machine direction; MD direction), a method of stretching (transverse stretching) by fixing both side edge portions of a film (F) with a jig or the like in a widthwise direction (direction orthogonal to a film surface; widthwise direction of a film; transverse direction; TD direction), a method of stretching (transverse stretching) by sequentially performing longitudinal stretching and transverse stretching (sequential biaxial stretching), a method of simultaneously performing longitudinal stretching and transverse stretching (simultaneous biaxial stretching), and the like, wherein a tenter stretching device is used in the transverse stretching and the simultaneous biaxial stretching (including oblique stretching).

The tenter stretching device stretches the film by holding both ends of the film in the width direction with jigs and expanding the gap while moving the jigs together with the film.

In the above method, in order to improve the performance, productivity, flatness, and dimensional stability of the film, a so-called tenter system using a tenter stretching apparatus is preferable.

In the case of the so-called tenter method, if the clip portion is driven by a linear drive system, smooth stretching can be performed, and the risk of breakage or the like can be reduced, which is preferable.

The width retention and the stretching in the transverse direction in the film forming step are preferably performed by a tenter stretching device, and may be a pin tenter or a clip tenter.

In addition to the stretching, the stretching device (7) may be used for drying.

(draw ratio)

In order to ensure a high retardation, a wide width, and promote penetration of an adhesive at the time of adhesion 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, cracks may be generated in the film due to the stretching stress, or entanglement between molecules of the matrix which maintains the strength of the film may be dissociated, and the film may be weakened.

Therefore, the stretching ratio in the stretching step is preferably in the range of 1.1 to 5.0 times, more preferably in the range of 1.3 to 3.0 times.

In the present invention, the term "stretch ratio" means a ratio of the area of the film after stretching to the area of the film before stretching [% ].

That is, in the "stretch ratio" in the above-described stretching process, the total stretch ratio based on stretching in the longitudinal (long side) direction and the transverse (wide side) direction of the film is preferably in the range of 1.1 to 5.0 times, more preferably in the range of 1.3 to 3.0 times in terms of area ratio.

In the case of performing the stretching plural times, the stretching at the highest magnification in which the risk of dissociation of the matrix molecule is highest among the stretching plural times is preferably performed at the last time.

For example, in fig. 7, the stretching at the highest magnification is preferably performed in the 2 nd stretching step.

In this case, entanglement of the matrix molecules can be made firm before the stretching at the highest magnification, so that dissociation of entanglement of the matrix molecules can be suppressed and cohesive failure can be suppressed even when the stretching at the highest magnification is performed.

(tenter stretching device)

Hereinafter, a case where a tenter stretching device is used as the stretching device (7) will be described as an example with reference to fig. 9, 10, 11, and 12.

Fig. 9 is a plan view schematically showing the internal structure of the tenter stretching device, and is a cross-sectional view of the tenter stretching device when the surface perpendicular to the surface of the film is viewed from the upper side.

Fig. 10 shows a state in which the cover of the tenter stretching device is removed, and the cover is indicated by a two-dot chain line.

Fig. 11 is a schematic view of the nozzle and heater arrangement portion when the 3 regions in the tenter stretching device are viewed from the front.

As shown in fig. 11, the Infrared (IR) heater is disposed only on the upper side of the nozzle so that the film does not come into contact with the Infrared (IR) heater when the film breaks, but the Infrared (IR) heater is brought close to the film so that the radiation energy of the Infrared (IR) heater can be concentrated in a narrower range, and therefore the Infrared (IR) heater is brought as close to the film as possible within a range that does not interfere with the width adjustment operation by the jig.

In fig. 11, the heat treatment from the center nozzle (105) is mainly shown, but the heat treatment of the end nozzle (104) is not performed in the present example, but may be used in combination in the present embodiment.

In the heat treatment, as shown in fig. 12, an Infrared (IR) heater comes out of the nozzle gap to be able to transmit radiant energy to the film without waste.

As shown in fig. 9, in the film before stretching, infrared (IR) heaters are also arranged in a row so as to be able to heat the entire width.

The heaters may be arranged in a staggered manner in the longitudinal direction.

A tenter stretching device (40) is provided with a plurality of clips (42) for holding both ends of a film (F) in the width direction, and the clips (42) are attached to an endless chain (48) at a constant interval.

An endless chain (48) is disposed on both sides with the film (F) interposed therebetween, and is respectively stretched between a driving sprocket (50) on the inlet side and a driven sprocket (52) on the outlet side.

The drive sprocket (50) is connected to a motor, not shown, and the drive sprocket (50) is rotated by driving the motor.

Thus, the endless chain (48) travels around between the driving sprocket (50) and the driven sprocket (52), and thus the jigs (42) mounted to the endless chain (48) travel around.

A rail (54) for guiding the endless chain (48) (or the jig (42)) is provided between the drive sprocket (50) and the driven sprocket (52).

The rails (54) sandwich the film (F) and are arranged on both sides, and the interval between the rails (54) is configured as follows: the downstream side of the film (F) in the conveying direction is wider than the upstream side.

As a result, the distance between the clips (42) is increased when the clips (42) travel around, and therefore the film (F) held by the clips (42) can be stretched laterally in the widthwise direction.

Opening members (56) are respectively attached to the driving sprocket (50) and the driven sprocket (52).

The opening member (56) is a device for displacing a shutter (not shown) of the gripper (42) described later from a gripping position to an opening position, and the gripping operation and the opening operation of the film (F) are automatically performed by the opening member (56).

However, as shown in fig. 9, 10 and 12, the inside of the tenter stretching device (40) is provided with a preheating zone, (transverse) stretching zone and a heat-setting zone.

The regions are separated from each other by a blind (not shown).

In addition, hot air is supplied to the film (F) from above or below or both in each region.

The hot air is uniformly blown out along the width direction of the film (F) in a state where each region is controlled to a given temperature.

Thereby, the inside of each region is controlled to a desired temperature. The following describes each region.

The preheating region is a region where the film (F) is preheated, and the film (F) is heated without expanding the interval between the jigs (42).

The film (F) preheated in the preheating zone is moved to the (transverse) stretching zone.

The (transverse) stretching region is a region in which the film (F) is stretched in the widthwise direction by expanding the interval between the jigs (42).

The stretching ratio in the (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.

The film (F) which has been subjected to the transverse stretching in the transverse stretching region is moved to the heat-set region.

In the present embodiment, the interior of the tenter stretching device (40) is divided into a preheating zone, a (transverse) stretching zone, and a heat-set zone, but the type and arrangement of the zones are not limited to this, and for example, a cooling zone for cooling the film (F) may be provided after the (transverse) stretching zone.

In addition, a heat relaxing region may be provided in the heat fixing region.

In the present embodiment, only (transverse) stretching is performed by the tenter stretching device (40), but stretching may be performed simultaneously in the longitudinal direction.

In this case, when the jigs (42) are moved, the pitch of the jigs (42) (the interval between the jigs (42) in the conveying direction) may be changed.

As a mechanism for changing the pitch of the jigs 42, a scaling mechanism or a linear guide mechanism can be used, for example.

(timing of heat treatment)

The tenter stretching apparatus is generally divided into a plurality of regions, and includes, for example, a preheating region for heating the film, a transverse stretching region for stretching the film in the transverse direction, a heat setting region for crystallizing the film, a relaxation region for removing thermal stress of the film, and the like, as shown in fig. 9, 10, and 12.

(temperature in furnace)

In general, the temperature in the furnace is preferably in the range of 120 to 200℃and more preferably in the range of 120 to 180 ℃.

The "in-furnace temperature" herein means a temperature (H) obtained by measuring a position 100mm above the center of the film immediately before stretching in a stretching region of a tenter stretching apparatus to be described later _A =100 mm), the value of each temperature every 1 minute was measured for 1 hour, and the average value thereof was calculated.

In general, the temperature in the furnace is preferably in the range of 120 to 200 ℃, more preferably in the range of 120 to 180 ℃.

Here, when a temperature gradient is applied to the long side among the plurality of partitions, the heat-treated partition is targeted.

In addition, the temperature in the furnace is different between the case where the heat treatment is performed in the stretching region and the case where the heat treatment is not performed in the stretching region, and the temperature in the furnace is the temperature in the stretching region before the heat treatment is performed in the stretching region.

(residual solvent amount)

The amount of the residual solvent in the film at the time of stretching is preferably 20 mass% or less, and more preferably 15 mass% or less.

(2.1.7) 1 st cutting step [ S7]

In the 1 st cutting step (S7), a cutting section (8) comprising a slitter cuts both ends in the widthwise direction of the film (F) stretched in the 1 st stretching step (S6).

In the film (F), the remaining portions after cutting of both end portions constitute a product portion which becomes a film product.

On the other hand, the portion cut from the film (F) may be recovered and reused as a part of the raw material for film production.

(2.1.8) 2 nd stretching step [ S8]

In the 2 nd stretching step [ S8], the film (F) is stretched by a stretching device (9) in the same manner as in the 1 st stretching step [ S6 ].

In this case, in order to improve the film performance, productivity, flatness, and dimensional stability, a stretching method in which a roll peripheral speed difference is provided and stretching is performed in a conveying direction (MD direction), and a tenter method in which both side edge portions of the film (F) are fixed by a jig or the like and stretched in a widthwise direction (TD direction) are preferable.

In addition to the stretching, the stretching device (9) may be used for drying.

(2.1.9) the 2 nd cutting step [ S9]

In the 2 nd cutting step [ S9], both ends of the film (F) after film formation in the widthwise direction are cut by a cutting section (10) including a slitter in the same manner as in the 1 st cutting step [ S7 ].

The holding portions of the jigs at both ends of the film are generally cut out because the film is deformed and cannot be used as a product.

When the material is not degraded by heat, the material is recycled after recovery.

On the other hand, the portion cut from the film (F) is recovered and reused as a part of the raw material for film production.

(2.1.10) the 2 nd drying step [ S10]

In the 2 nd drying step [ S10], the film (F) is dried by a drying device (11) in the same manner as in the 1 st drying step [ S5 ].

In the drying device (11), the film (F) is conveyed by a plurality of conveying rollers which are arranged in a staggered manner when seen from the side, and the film (F) is dried in the middle.

The drying method in the drying device (6) is not particularly limited, and examples thereof include hot air, infrared rays, heating rolls, microwaves, and the like.

Among the above drying methods, a method of drying the film (F) with hot air is preferable from the viewpoint of convenience.

The 2 nd drying step [ S10] may be performed as needed.

(2.1.11) 3 rd cutting step [ S11]

In the 3 rd cutting step [ S11], both ends of the film (F) after film formation in the widthwise direction are cut by a cutting section (12) including a slitter in the same manner as in the 1 st cutting step [ S7] and the 2 nd cutting step [ S9 ].

(2.1.12) winding step [ 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 the winding core while being conveyed, thereby producing a film roll.

The initial tension in winding the film in the winding step is preferably in the range of 20 to 300N/m.

Fig. 13 is a schematic view showing a step of winding a film and a cross section of a film roll of the present invention after winding.

When winding the film (F), for example, it is preferable to provide a touch roller (33) as shown in fig. 13, and to appropriately change the film touch pressure so as to form a desired void layer.

In fig. 13, a film (31) after film formation is wound by a roller (32) and a touch roller (33), and is wound as a film roll (30).

(residual solvent amount)

More specifically, the film is wound by a winding device (12) as a film after the amount of the residual solvent in the film is 2 mass% or less, and the film having good dimensional stability can be obtained by setting the amount of the residual solvent to 0.4 mass% or less.

Particularly, the winding is preferably performed in a range of 0.00 to 0.20 mass% of the residual solvent amount.

(winding method)

The film (F) may be wound by a winding machine commonly used, and the tension may be controlled by a constant torque method, a constant tension method, a taper tension method, a program tension control method with constant internal stress, or the like.

Before winding, the end portions are cut into the width of the product, and in order to prevent adhesion and scratch in the roll, both ends of the film may be subjected to a surface modification treatment.

(after winding)

The film roll of the present invention is preferably a long film, and specifically, it is a film roll in a form of being provided in a roll shape, which is in a range of about 100 to 10000 m.

(2.2) Process for producing film roll by melt casting film-forming method

The film of the present invention may be formed by a melt-casting film-forming method.

The "melt film forming method" refers to a method in which a composition containing a thermoplastic resin and the additive is heated and melted to a temperature at which fluidity is exhibited, and then the melt containing the thermoplastic resin having fluidity is cast.

The molding method by heat melting is classified into a melt extrusion molding method, a compression molding method, a inflation method, an injection molding method, a blow molding method, a stretch molding method, and the like.

Among these molding methods, the melt extrusion method is preferable in terms of mechanical strength, surface accuracy, and the like.

Fig. 14 is a flowchart showing a flow of a manufacturing process by the melt-casting film forming method.

Fig. 15 is a schematic view of an apparatus for producing a film by a melt-casting film-forming method.

Hereinafter, the solution casting film forming method will be described with reference to fig. 14 and 15.

The method for producing a film roll by a melt casting film-forming method comprises: extrusion step [ M1], casting/molding step [ M2], 1 st stretching step [ M3], 1 st cutting step [ M4], 2 nd stretching step [ M5], 2 nd cutting step [ M6] and winding step [ M7].

The production method does not need to include both the 1 st stretching step [ M3] and the 2 nd stretching step [ M5], and may include at least one step.

The 1 st cutting step [ M4] and the 2 nd cutting step [ M6] may include at least one step in the same manner.

(2.2.1) extrusion Process [ M1]

In the extrusion step [ M1], at least the resin is melt-extruded by an extruder (14) and molded on a casting drum (16).

Details of the resin that can be used in the present invention are described later.

In addition, the resin is preferably kneaded and pelletized in advance.

Granulation can be carried out by a known method.

For example, the dry resin, plasticizer, and other additives may be fed to an extruder by a feeder, kneaded by a uniaxial or biaxial extruder, extruded in a strand form from a casting die (15), water-cooled or air-cooled, and cut, and pelletized.

The additive may be mixed with the resin before being fed to the extruder, or the additive and the resin may be fed to the extruder separately using separate feeders.

In addition, in order to uniformly mix small amounts of additives such as particles and antioxidants, it is preferable to mix them in advance in the resin.

When the pellets are introduced from the feed hopper into the extruder, it is preferable to prevent oxidative decomposition or the like under drying, vacuum or reduced pressure, or under an inert gas atmosphere.

The extruder is preferably capable of granulating the resin so as to suppress shearing force and prevent deterioration of the resin (such as reduction in molecular weight, coloration, and gel formation), and processing the resin at a temperature as low as possible.

For example, in the case of a twin-screw extruder, it is preferable to use a screw of a deep-groove type to rotate in the same direction.

From the viewpoint of uniformity of kneading, the mesh type is preferable.

The resin and the particles are preferably filtered by a leaf disk filter or the like to remove foreign matters during melting.

Film formation was performed using the particles obtained as described above.

Needless to say, the resin (powder, etc.) as a raw material may be directly fed to the extruder through a feeder without being pelletized, and film formation may be directly performed.

(2.2.2) casting and Forming Process [ M2]

In the casting/molding step [ M2], the resin/pellets melted in the extrusion step are cast into a film form from a casting die (15) through a pipe by a pressurized quantitative gear pump or the like, and the melted resin/pellets are cast from the casting die (15) to a casting position on a rotary-driven stainless steel endless casting drum (16) that is infinitely transferred.

The resin/particles in a molten state after casting are molded on a casting drum (16) to form a casting film (18).

The inclination of the casting die (15), that is, the ejection direction of the molten resin/particles from the casting die (15) to the support (16), may be appropriately set so that the angle with respect to the normal line of the surface of the casting drum (16) (the surface on which the molten resin/particles are cast) is in the range of 0 to 90 degrees.

The film (F) may be formed by appropriately combining the touch roller (16 a) and the cooling roller (17) of the auxiliary casting roller (16).

(2.2.3) 1 st stretching step [ M3]

In the 1 st stretching step [ M3], the film (F) is stretched by a stretching device (19).

In this case, in order to improve the film performance, productivity, flatness, and dimensional stability, a stretching method in which the film is stretched in the MD direction by a difference in peripheral speed of rolls, and a tenter method in which both side edge portions of the film (F) are fixed by a jig or the like and stretched in the TD direction are preferably provided.

In addition to the stretching, the stretching device (19) may be used for drying.

The description of the tenter stretching apparatus, the heat treatment timing, the temperature in the furnace, the stretching temperature, the temperature in the stretching furnace, the amount of residual solvent, and the like is repeated with the 1 st stretching step [ S6] in the process of producing the film roll by the solution casting film forming method, and therefore is omitted.

(2.2.4) 1 st cutting step [ M4]

In the 1 st cutting step (M4), a cutting part (20) comprising a slitter cuts both ends of the film (F) after film formation in the width direction.

(2.2.5) 2 nd stretching step [ M5]

In the 2 nd stretching step [ M5], the film (F) is stretched by a stretching device (21) in the same manner as in the 1 st stretching step [ M3 ].

In addition to the stretching, the stretching device (21) may be used for drying.

(2.2.6) 2 nd cutting step [ M6]

In the 2 nd cutting step [ M6], both ends of the film (F) after film formation in the widthwise direction are cut by a cutting section (22) including a slitter in the same manner as in the 1 st cutting step [ M4 ].

(2.2.7) winding step [ 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 the winding core while being conveyed, thereby producing a film roll.

3. Film-forming resins

(3.1) thermoplastic resin

The thermoplastic resin material used in the film of the present invention is not limited as long as it can be handled as a film roll after the film is formed.

Examples of thermoplastic resins used for polarizing plates include cellulose ester resins such as Triacetate (TAC), cellulose Acetate Propionate (CAP) and Diacetate (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).

However, COP is preferably used in terms of easy control of stretchability and crystallinity, easy penetration of an adhesive, and ensuring more excellent adhesion to a polarizer.

The film may be subjected to a surface modification treatment after production.

Furthermore, the effect of the invention is of increased value in the film region.

The thickness of the film is preferably in the range of 5 to 80. Mu.m, more preferably in the range of 10 to 65. Mu.m, and even more preferably in the range of 10 to 45. Mu.m.

When the film thickness is 5 μm or more, the film roll has high rigidity and is easy to maintain the roll shape.

If the film thickness is 80 μm or less, the quality will not be excessively increased, and a long film roll can be easily produced.

(3.1.1) cycloolefin resin

The cycloolefin resin contained in the film roll of the present invention is preferably a polymer of cycloolefin monomer or a copolymer of cycloolefin monomer and a copolymerizable monomer other than the cycloolefin monomer.

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).

[ chemical formula 1]

General formula (A-l)

In the 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. p represents an integer of 0 to 2. However, R is ¹ ～R ⁴ All of them not simultaneously representing hydrogen atoms, R ¹ And R is ² Not simultaneously representing hydrogen atoms, R ³ And R is ⁴ Not simultaneously representing hydrogen atoms.

In the general formula (A-1), R is as follows ¹ ～R ⁴ The hydrocarbyl group having 1 to 30 carbon atoms represented is, for example, preferably a hydrocarbyl group having 1 to 10 carbon atoms, and more preferably a hydrocarbyl group having 1 to 5 carbon atoms.

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 carbonyl, imino, ether linkage, silyl ether linkage, thioether linkage, and the like.

Examples of the hydrocarbon group having 1 to 30 carbon atoms include: methyl, ethyl, propyl, butyl, and the like.

In the general formula (A-1), R ¹ ～R ⁴ Examples of the polar group represented include: carboxyl, hydroxyl, alkoxy, alkoxycarbonyl, aryloxycarbonyl, amino, amido and cyano.

Among them, carboxyl group, hydroxyl group, alkoxycarbonyl group and aryloxycarbonyl group are preferable, and alkoxycarbonyl group and aryloxycarbonyl group are preferable from the viewpoint of securing solubility at the time of solution film formation.

From the viewpoint of improving the heat resistance of the film, p in the general formula (A-1) is preferably 1 or 2.

This is because if p is 1 or 2, the steric hindrance of the resulting polymer becomes high, and the glass transition temperature tends to be high.

[ chemical formula 2]

General formula (A-2)

In the 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. R is R ⁶ Represents a carboxyl group, a hydroxyl group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amide group, a cyano group or a halogen atom (fluorine atom, chlorine atom, bromine atom or iodine atom). p represents an integer of 0 to 2.

R in the general formula (A-2) ⁵ Preferably a hydrocarbon group having 1 to 5 carbon atoms, more preferably a hydrocarbon group having 1 to 3 carbon atoms.

R in the general formula (A-2) ⁶ Preferably represents a carboxyl group, a hydroxyl group, an alkoxycarbonyl group and an aryloxycarbonyl group, and more preferably an alkoxycarbonyl group and an aryloxycarbonyl group from the viewpoint of securing solubility in a solution for film formation.

From the viewpoint of improving the heat resistance of the film, p in the general formula (a-2) preferably represents 1 or 2.

This is because if p represents 1 or 2, the steric hindrance of the resulting polymer becomes high and the glass transition temperature tends to be high.

Cycloolefin monomers having a structure represented by the general formula (A-2) are preferable in terms of improving the solubility in an organic solvent.

In general, the organic compound has crystallinity reduced by breaking symmetry, and thus solubility in an organic solvent is improved.

R in the general formula (A-2) ⁵ And R is ⁶ Since the symmetry of the molecule is low because the symmetry of the molecule is substituted with only one-sided ring constituent carbon atoms, that is, the cycloolefin monomer having the structure represented by the general formula (A-2) has high solubility, and is therefore suitable for producing a film by a solution casting film formation method.

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

If the cycloolefin monomer having a structure represented by the general formula (A-2) is contained at least a certain amount, the orientation of the resin is improved, and thus the value of the retardation (phase retardation) is liable to rise.

Specific examples of cycloolefin monomers having the structure represented by the general formula (A-1) are shown in the examples of the compounds 1 to 14, and specific examples of cycloolefin monomers having the structure represented by the general formula (A-2) are shown in the examples of the compounds 15 to 34.

[ chemical formula 3]

Examples of copolymerizable monomers copolymerizable with cycloolefin monomers include: a copolymerizable monomer ring-opening copolymerizable with a cycloolefin monomer, a copolymerizable monomer addition-copolymerizable with a cycloolefin monomer, and the like.

Examples of the ring-opening copolymerizable monomer include: cycloolefins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, dicyclopentadiene, and the like.

Examples of addition copolymerizable comonomers include: unsaturated double bond-containing compounds, vinyl cyclic hydrocarbon monomers, and (meth) acrylic esters, and the like.

Examples of the unsaturated double bond-containing compound include: an olefin compound having 2 to 12 carbon atoms (preferably 2 to 8), examples of which include: ethylene, propylene, and butylene, and the like.

Examples of vinyl-based cyclic hydrocarbon monomers include: vinyl cyclopentene monomers such as 4-vinyl cyclopentene and 2-methyl-4-isopropenyl cyclopentene.

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

The content of the cycloolefin monomer in the copolymer of the cycloolefin monomer and the copolymerizable monomer may be, for example, 20 to 80 mol%, and preferably 30 to 70 mol% based on the total of all the monomers constituting the copolymer.

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 the general formula (A-1) or (A-2), and examples thereof include: the following polymers (1) to (7).

(1) Ring-opened polymers of cycloolefin monomers

(2) Ring-opened copolymer of cycloolefin monomer and copolymerizable monomer ring-opened copolymerizable therewith

(3) The hydrogenated product of the ring-opened (co) polymer of (1) or (2)

(4) Cyclizing the ring-opened (co) polymer of (1) or (2) by Friedel Crafts reaction, followed by addition of hydrogen to the (co) polymer

(5) Saturated copolymers of cycloolefin monomers with compounds containing unsaturated double bonds

(6) Addition copolymer of cycloolefin monomer and vinyl cyclic hydrocarbon monomer and hydrogenated product thereof

(7) Alternating copolymers of cycloolefin monomers with (meth) acrylic esters

The polymers of the above-mentioned (1) to (7) can be obtained by a known method, for example, a method described in Japanese patent application laid-open No. 2008-107534, and Japanese patent application laid-open No. 2005-227606.

For example, as the catalyst and solvent used in the ring-opening copolymerization of the above-mentioned (2), for example, those described in paragraphs 0019 to 0024 of Japanese patent application laid-open No. 2008-107534 can be used.

The catalysts used in the hydrides of (3) and (6) are, for example, those described in paragraphs 0025 to 0028 of Japanese patent application laid-open No. 2008-107534.

The acidic compound used in the Friedel Crafts reaction of (4) can be, for example, as described in paragraph 0029 of Japanese patent application laid-open No. 2008-107534.

The catalysts used in the addition polymerization of (5) to (7) may be those described in paragraphs 0058 to 0063 of Japanese patent application laid-open No. 2005-227606.

The alternating copolymerization of (7) can be carried out by, for example, the methods described in paragraphs 0071 and 0072 of Japanese patent application laid-open No. 2005-227606.

Among them, the polymers of (1) to (3) and (5) are preferable, and the polymers of (3) and (5) are more preferable.

That is, from the viewpoint of being able to raise the glass transition temperature of the resulting cycloolefin resin and to improve the light transmittance, the cycloolefin resin preferably contains at least one of the structural unit represented by the following general formula (B-1) and the structural unit represented by the following general formula (B-2), more preferably contains only the structural unit represented by the general formula (B-2) or contains both the structural unit represented by the general formula (B-1) and the structural unit represented by the general formula (B-2).

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

[ chemical formula 4]

General formula (B-1)

In the general formula (B-1), X represents-CH=CH-or-CH 2CH2-. R is R ¹ ～R ⁴ And p is independently of R of the formula (A-1) ¹ ～R ⁴ Synonymous with p.

[ chemical formula 5]

General formula (B-2)

In the general formula (B-2), X represents-CH=CH-or-CH =CH ₂ CH ₂ -。R ⁵ ～R ⁶ And p is independently of R of the formula (A-2) ⁵ ～R ⁶ Synonymous with p.

The cycloolefin resin according to the present invention can be commercially available.

Examples of commercial products of cycloolefin resins include: ARTON G (e.g., G7810, etc.), ARTON F, ARTON R (e.g., R4500, R4900, R5000, etc.), and ARTON RX, manufactured by JSR (corporation).

Intrinsic viscosity [ eta ] of cycloolefin resin]inh is preferably 0.2 to 5cm in a measurement at 30 DEG C ³ In the range of/g, more preferably 0.3 to 3cm ³ In the range of/g, it is more preferably 0.4 to 1.5cm ³ In the range of/g.

The number average molecular weight (Mn) of the cycloolefin resin is preferably 8000 to 100000, more preferably 10000 to 80000, and even more preferably 12000 to 50000.

The weight average molecular weight (Mw) of the cycloolefin resin is preferably in the range of 20000 to 300000, more preferably in the range of 30000 to 250000, and even more preferably in the range of 40000 to 200000.

The number average molecular weight and the weight average molecular weight of the cycloolefin resin can be measured by Gel Permeation Chromatography (GPC) in terms of polystyrene.

(gel permeation chromatography)

Solvent: dichloromethane (dichloromethane)

Column: shodex K806, K805, K803G (3 Showa Denko Co., ltd.)

Column temperature: 25 DEG C

Sample concentration: 0.1 mass%

A detector: RI Model 504 (GL SCIENCE company)

And (3) a pump: l6000 (Hitachi manufacturing Co., ltd.)

Flow rate: 1.0mL/min

Calibration curve: calibration curves for 13 samples in the range of mw=500 to 2800000 of standard polystyrene STK standard polystyrene (TOSOH (manufactured by TOSOH corporation)) were used. The 13 samples are preferably used at substantially equal intervals.

When the intrinsic viscosity [ eta ] inh, the number average molecular weight and the weight average molecular weight are within the above-mentioned ranges, the cycloolefin resin is excellent in heat resistance, water resistance, chemical resistance, mechanical properties and molding processability as a film.

The cycloolefin resin has a glass transition temperature Tg [ DEG C ] of usually 110 ℃ or higher, preferably 110 to 350 ℃, more preferably 120 to 250 ℃, and still more preferably 120 to 220 ℃.

When the glass transition temperature Tg [ deg. ] is 110 ℃ or higher, deformation under high temperature conditions is easily suppressed.

On the other hand, when the glass transition temperature Tg [ DEG C ] is 350 ℃ or lower, molding processing becomes easy, and deterioration of the resin due to heat during molding processing is easily suppressed.

The content of the cycloolefin resin is preferably 70% by mass or more, more preferably 80% by mass or more, relative to the film.

(3.1.2) acrylic resin

The acrylic resin of the present invention is a polymer of acrylic acid esters or methacrylic acid esters, and also includes copolymers with other monomers.

Therefore, the acrylic resin of the present invention also contains methacrylic resin.

The resin is not particularly limited, but a resin having methyl methacrylate units in the range of 50 to 99 mass% and other monomer units copolymerizable therewith in the range of 1 to 50 mass% is preferable.

As other units constituting the acrylic resin formed by copolymerization, there are given: alkyl methacrylates having 2 to 18 carbon atoms in the alkyl group, alkyl acrylates having 1 to 18 carbon atoms in the alkyl group, isobornyl methacrylates, hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate, acrylamides such as acrylic acid and methacrylic acid, unsaturated group-containing dicarboxylic acids such as acryloylmorpholine and N-hydroxyphenylmethacrylamide, N-vinylpyrrolidone, maleic acid, fumaric acid and itaconic acid, aromatic vinyl compounds such as styrene and alpha-methylstyrene, and alpha, beta-unsaturated nitriles such as acrylonitrile and methacrylonitrile, maleic anhydride, maleimide, N-substituted maleimide, glutarimide and glutarimide.

The copolymerizable monomer forming the unit from which the glutarimide and the glutarimide are removed includes monomers corresponding to the above units.

Namely, there can be mentioned: alkyl methacrylates having 2 to 18 carbon atoms in the alkyl group, alkyl acrylates having 1 to 18 carbon atoms in the alkyl group, isobornyl methacrylates, hydroxyalkyl acrylates such as 2-hydroxyethyl acrylate, acrylamides such as acrylic acid and methacrylic acid, unsaturated group-containing dicarboxylic acids such as acryloylmorpholine and N-hydroxyphenylmethacrylamide, N-vinylpyrrolidone, maleic acid, fumaric acid and itaconic acid, aromatic vinyl compounds such as styrene and alpha-methylstyrene, and monomers such as alpha, beta-unsaturated nitriles such as acrylonitrile and methacrylonitrile, maleic anhydride, maleimide and N-substituted maleimide.

Further, the glutarimide unit can be formed by, for example, reacting an intermediate resin having a (meth) acrylate unit with a primary amine (imidizing agent) to imidize (refer to japanese patent application laid-open No. 2011-26563).

The glutaric anhydride unit can be formed, for example, by heating an intermediate resin having a (meth) acrylate unit (see japanese patent No. 4961164).

In the acrylic resin of the present invention, the structural unit preferably includes: isobornyl methacrylate, acryloylmorpholine, N-hydroxyphenylmethacrylamide, N-vinylpyrrolidone, styrene, hydroxyethyl methacrylate, maleic anhydride, maleimide, N-substituted maleimide, glutaric anhydride or glutarimide.

The weight average molecular weight (Mw) of the acrylic resin of the present invention is preferably in the range of 50000 ～ 1000000, more preferably in the range of 100000 ～ 1000000, and particularly preferably in the range of 200000 ～ 800000, from the viewpoint of controlling dimensional changes with respect to changes in the atmospheric temperature and humidity of the environment, and from the viewpoint of improving peelability of a metal support, drying property of an organic solvent, heat resistance, and mechanical strength at the time of film production.

When the temperature is 50000 or more, the heat resistance and the mechanical strength are excellent, and when the temperature is 1000000 or less, the releasability from the metal support and the drying property of the organic solvent are excellent.

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

Here, as the polymerization initiator, general polymerization initiators of peroxides and azo groups may be used, and redox groups may also be employed.

As regards the polymerization temperature, suspension or emulsion polymerization can be carried out in the range from 30 to 100℃and bulk or solution polymerization can be carried out in the range from 80 to 160 ℃.

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

From the viewpoint of maintaining the mechanical strength of the film, the glass transition temperature Tg [ DEG C ] of the acrylic resin is preferably in the range of 80 to 120 ℃.

As the acrylic resin of the present invention, a commercially available acrylic resin may be used.

Examples include: DELMET 60N, 80N, 980N, SR8200 (above, manufactured by Asahi Kagaku chemical Co., ltd.), dianal BR52, BR80, BR83, BR85, BR88, EMB-143, EMB-159, EMB-160, EMB-161, EMB-218, EMB-229, EMB-270, EMB-273 (above, manufactured by MITSUBISHI RAYON Co., ltd.), KT75, TX400S, and IPX012 (above, manufactured by electric chemical industry Co., ltd.), and the like.

The acrylic resin may be used in combination of two or more.

The acrylic resin of the present invention preferably contains an additive, and as an example of the additive, acrylic particles (rubber elastomer particles) described in international publication No. 2010/001668 are preferably contained for the purpose of improving the mechanical strength of a film and adjusting the dimensional change rate.

Examples of the commercial products of the acrylic granular composite having such a multilayer structure include: "METABLEN W-341" manufactured by MITSUBISHI RAYON, "KANEACE" manufactured by KANEKA, "PARALOID" manufactured by KUREHA, "ACRYLOID" manufactured by ROHM AND HAAS, "STAFYROID" manufactured by AICA, "CHEMISNOW MR-2G, MS-300X (above," PARAPET SA "manufactured by KURARAY Co., ltd.) AND the like may be used singly or in combination.

The volume average particle diameter of the acrylic particles is 0.35 μm or less, preferably 0.01 to 0.35 μm, and more preferably 0.05 to 0.30 μm.

If the particle size is not less than a certain value, the film can be easily stretched under heating, and if the particle size is not more than a certain value, the transparency of the obtained film is not easily impaired.

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

The flexural modulus varies depending on the type and amount of the acrylic resin and the rubber elastomer particles in the film, and generally decreases as the content of the rubber elastomer particles increases.

In addition, when a copolymer of an alkyl methacrylate and an alkyl acrylate or the like is used as the acrylic resin, the flexural modulus is generally smaller than that of a homopolymer of an alkyl methacrylate.

(3.1.3) cellulose ester resin

In the film roll of the present invention, a cellulose ester resin is also preferably used.

The cellulose ester used in the present invention refers to a cellulose acylate resin in which part or all of the hydrogen atoms of hydroxyl groups (-OH) at the 2-, 3-and 6-positions in glucose units bonded to β -1,4 constituting the cellulose are substituted with acyl groups.

The 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, a cyclic carboxylic acid, or an aromatic carboxylic acid.

Examples of the above-mentioned cellulose esters include cellulose esters in which a hydrogen atom of a hydroxyl 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 pentanoyl group (valyl group), a pivaloyl group, a hexanoyl group, an octanoyl group, a lauroyl group, and a stearoyl group.

The carboxylic acid (acyl group) constituting the ester may have a substituent.

The carboxylic acid constituting the ester is particularly preferably a lower fatty acid having 6 or less carbon atoms, and more preferably a lower fatty acid having 3 or less carbon atoms.

The acyl group in the cellulose ester may be one or a combination of a plurality of acyl groups.

Specific examples of the preferable cellulose ester include cellulose acetate such as diacetyl cellulose (DAC) and triacetyl cellulose (TAC), cellulose Acetate Propionate (CAP), cellulose acetate butyrate, and mixed fatty acid esters of cellulose having a propionate group or a butyrate group bonded to an acetyl group such as cellulose acetate propionate butyrate.

These cellulose esters may be used singly or in combination.

(species of acyl group, substitution degree)

By adjusting the type and substitution degree of the acyl group of the cellulose ester, the variation in humidity of the phase difference can be controlled within a desired range, and the uniformity of the film thickness can be improved.

The smaller the degree of substitution of acyl groups of cellulose esters, the more the retardation appearance improves, and thus the film can be made thinner.

On the other hand, if the substitution degree of the acyl group is too small, there is a risk of deterioration in durability, so that it is not preferable.

On the other hand, as the degree of substitution of acyl groups of cellulose esters increases, retardation is not exhibited, and therefore, it is necessary to increase the stretching ratio at the time of film formation, but it is difficult to uniformly stretch at a high stretching ratio, and therefore, variation in film thickness becomes large (deterioration).

Further, since the variation in Rt humidity, which is the phase retardation (retardation) in the thickness direction, occurs due to the coordination of water molecules with the carbonyl groups of cellulose, the higher the degree of substitution of acyl groups, that is, the more carbonyl groups in cellulose, the worse the variation in Rt humidity tends to be.

The cellulose ester preferably has a total substitution degree in the range of 2.1 to 2.5.

By setting the range to this, environmental fluctuations (particularly, rt fluctuations due to humidity) can be suppressed, and uniformity of film thickness can be improved.

From the viewpoint of improving the flow and stretchability in film formation and further improving the uniformity of the film thickness, it is more preferably in the range of 2.2 to 2.45.

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

Formula (a): X+Y is more than or equal to 2.1 and less than or equal to 2.5

Formula (b): y is more than or equal to 0 and less than or equal to 1.5

Cellulose esters are more preferably cellulose acetate (y=0) and Cellulose Acetate Propionate (CAP) (Y; propionyl, Y > 0), and from the viewpoint of reducing the variation in film thickness, more preferably cellulose acetate of y=0.

From the viewpoint of bringing the retardation expression, the variation in Rt humidity, and the variation in film thickness into desired ranges, cellulose acetate (DAC) in which X is 2.1 to 2.5 (more preferably 2.15 to 2.45) is particularly preferably used.

In the case of Y >0, cellulose Acetate Propionate (CAP) is particularly preferably used in which X.ltoreq.X.ltoreq.2.25, Y.ltoreq.0.1.ltoreq.1.2, and X.ltoreq.X+Y.ltoreq.2.45.

By using the cellulose acetate or cellulose acetate propionate, a film roll excellent in phase retardation, mechanical strength, and environmental fluctuation can be obtained.

The substitution degree of the acyl group means the average number of acyl groups per 1 glucose unit, and several hydrogen atoms of hydroxyl groups at the 2-, 3-and 6-positions of the 1 glucose unit are substituted with the acyl group.

Therefore, the maximum substitution degree is 3.0, which means that all of the hydrogen atoms of the hydroxyl groups at the 2-position, 3-position and 6-position are substituted with acyl groups.

These acyl groups may be substituted at the 2-, 3-, or 6-positions of the glucose unit on average, or may be substituted in a distributed manner.

The degree of substitution was determined by the method specified in ASTM-D817-96.

In order to obtain desired optical characteristics, cellulose acetate having different degrees of substitution may be used in combination.

In this case, the mixing ratio of the different cellulose acetates is not particularly limited.

The cellulose ester has a number average molecular weight (Mn) of 2X 10 ⁴ ～3×10 ⁵ Further within a range of 2X 10 ⁴ ～1.2×10 ⁵ Within (2), and further within 4 x 10) ⁴ ～8×10 ⁴ In the range (2), the mechanical strength of the film roll obtained is preferably increased.

The number average molecular weight (Mn) of the cellulose ester is calculated by measurement using Gel Permeation Chromatography (GPC) based on the above measurement conditions.

The cellulose ester has a weight average molecular weight (Mw) of 2X 10 ⁴ ～1×10 ⁶ Further within a range of 2X 10 ⁴ ～1.2×10 ⁵ And further in the range of 4 x 10 ⁴ ～8×10 ⁴ In the range (2), the mechanical strength of the film roll obtained is preferably increased.

The cellulose ester is not particularly limited, and examples thereof include cotton linter, wood pulp, kenaf, and the like.

The cellulose esters obtained from these may be used in any ratio.

Cellulose esters such as cellulose acetate and cellulose acetate propionate can be produced by a known method.

In general, raw cellulose, a given organic acid (acetic acid, propionic acid, etc.), an acid anhydride (acetic anhydride, propionic anhydride, etc.), and a catalyst (sulfuric acid, etc.) are mixed, and the mixture is subjected to esterification to react until a cellulose triester is formed.

In triesters, three hydroxyl groups of the glucose unit are replaced with acyloxy groups of the organic acid.

When two organic acids are used simultaneously, a mixed ester type cellulose ester, such as cellulose acetate propionate, cellulose acetate butyrate, can be prepared.

Next, a cellulose ester resin having a desired degree of acyl substitution is synthesized by hydrolyzing a triester of cellulose.

Then, the cellulose ester resin is produced by the steps of filtration, precipitation, washing with water, dehydration, drying, and the like. Specifically, it can be synthesized by referring to the method described in Japanese patent laid-open No. 10-45804.

(3.2) other additives

The film roll of the present invention may contain, as other additives, the following additives in addition to the thermoplastic resin.

(3.2.1) plasticizers

In order to impart processability to, for example, a polarizer protective film, the film roll of the present invention preferably contains at least one plasticizer.

The plasticizer is preferably used singly or in combination of two or more.

Among the plasticizers, at least one plasticizer selected from the group consisting of sugar esters, polyesters and styrene compounds is preferably contained from the viewpoint of achieving both high effective control of moisture permeability and compatibility with a base resin such as cellulose ester.

The molecular weight of the plasticizer is preferably 15000 or less, more preferably 10000 or less, from the viewpoint of improving the wet heat resistance and compatibility with a base resin such as cellulose ester.

When the compound having a molecular weight of 10000 or less is a polymer, the weight average molecular weight (Mw) is preferably 10000 or less.

The weight average molecular weight (Mw) is preferably in the range of 100 to 10000, more preferably 400 to 8000.

In particular, in order to obtain the effect of the present invention, the compound having a molecular weight of 1500 or less is preferably contained in a range of 6 to 40 parts by mass, and more preferably the compound having a molecular weight of 1500 or less is contained in a range of 10 to 20 parts by mass, relative to 100 parts by mass of the base resin.

The inclusion in the above range is preferable in that the moisture permeability can be effectively controlled and the compatibility with the base resin can be achieved.

(sugar esters)

The film roll of the present invention may contain a sugar ester compound in order to prevent hydrolysis.

Specifically, as the sugar ester compound, a sugar ester having at least one of a pyranose structure or a furanose structure of 1 to 12, and having all or part of the OH groups of the structure esterified can be used.

(polyester)

The film roll of the present invention may contain polyester.

The polyester is not particularly limited, and for example, a polymer having a hydroxyl group at the terminal (polyester polyol) obtained by a condensation reaction of a dicarboxylic acid or an ester-forming derivative thereof and a diol, or a polymer having a hydroxyl group at the terminal of the polyester polyol blocked with a monocarboxylic acid (blocked polyester) may be used.

The ester-forming derivative herein means an ester of a dicarboxylic acid, a dicarboxylic acid chloride, or an acid anhydride of a dicarboxylic acid.

(styrenes)

In the film roll of the present invention, a styrene compound may be used in addition to or instead of the above sugar ester or polyester for the purpose of improving the water resistance of the film.

The styrene compound may be a homopolymer of a styrene monomer or a copolymer of a styrene monomer and other comonomers.

In order to provide a steric hindrance of a molecular structure of a constant or higher, the content of the structural unit derived from the styrene monomer in the styrene compound may be preferably in the range of 30 to 100 mol%, more preferably in the range of 50 to 100 mol%.

Examples of styrenic 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; vinyl benzyl alcohol; alkoxy-substituted styrenes such as p-methoxystyrene, p-t-butoxystyrene and m-t-butoxystyrene; vinyl benzoic acids such as 3-vinyl benzoic acid and 4-vinyl benzoic acid; 4-vinylbenzyl acetate; 4-acetoxystyrene; amide styrenes such as 2-butylamide styrene, 4-methylamide styrene, and p-sulfonamide styrene; aminostyrenes such as 3-aminostyrene, 4-aminostyrene, 2-isopropenylaniline, and vinylbenzyl dimethylamine; nitrostyrenes such as 3-nitrostyrene and 4-nitrostyrene; cyanostyrenes such as 3-cyanostyrene and 4-cyanostyrene; vinyl phenyl acetonitrile; aryl styrenes such as phenyl styrene, indenes, and the like.

The styrene monomer may be one kind, or two or more kinds may be combined.

(3.2.2) optional ingredients

The film roll of the present invention may comprise: other optional components such as antioxidants, colorants, ultraviolet absorbers, matting agents, acrylic particles, hydrogen-bonding solvents, and ionic surfactants.

These components may be added in the range of 0.01 to 20 parts by mass relative to 100 parts by mass of the base resin.

(antioxidant)

The film roll of the present invention may use a conventionally known antioxidant as an antioxidant.

In particular, lactone compounds, sulfur compounds, phenol compounds, double bonds compounds, hindered amines, and phosphorus compounds can be preferably used.

These antioxidants and the like are added in the range of 0.05 to 20 mass%, preferably 0.1 to 1 mass%, to the resin as the main raw material of the film.

These antioxidants and the like can obtain synergistic effects by using a combination of a plurality of different kinds of compounds, as compared with the use of only one kind.

For example, the use of a combination of lactones, phosphorus compounds, phenols and double bond compounds is preferred.

(colorant)

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.

The colorant means a dye or a pigment, and in the present invention, means a colorant having an effect of changing the color tone of a liquid crystal screen to a blue color tone or a reduction in haze by adjusting a yellow index.

As the colorant, various dyes, pigments, anthraquinone dyes, azo dyes, phthalocyanine pigments, and the like are effective.

(ultraviolet absorber)

The film roll of the present invention may be used on the visible side or the backlight side of a polarizing plate, and may contain an ultraviolet absorber for the purpose of imparting an ultraviolet absorbing function.

The ultraviolet absorber is not particularly limited, and examples thereof include ultraviolet absorbers such as benzotriazoles, 2-hydroxybenzophenones, and phenyl salicylates.

Examples may include: triazoles such as 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [ 2-hydroxy-3, 5-bis (. Alpha.,. Alpha. -dimethylbenzyl) phenyl ] -2H-benzotriazole, 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 ultraviolet absorber may be used singly or in combination of two or more.

The amount of the ultraviolet absorber to be used varies depending on the type of the ultraviolet absorber, the conditions of use, and the like, and is usually in the range of 0.05 to 10 mass%, preferably 0.1 to 5 mass% with respect to the base resin.

(microparticles)

The film roll of the present invention preferably contains fine particles imparting slidability to the film roll.

In particular, the fine particles are also effective from the viewpoints of improving the slidability of the film surface of the present invention, improving the slidability at the time of winding, preventing the occurrence of damage and the occurrence of blocking.

The fine particles may be inorganic fine particles or organic fine particles, and are more preferably inorganic fine particles, as long as they do not impair the transparency of the obtained film roll and have heat resistance at the time of melting.

These fine particles may be used alone or in combination of two or more.

By using particles having different particle diameters and shapes (for example, needle-like and spherical shapes) in combination, both transparency and slidability can be achieved at a high level.

Among the compounds constituting the fine particles, silica having excellent transparency (haze) due to the refractive index close to that of the cycloolefin resin, acrylic resin, or cellulose ester resin is particularly preferably used.

Specific examples of SILICA include those having the trade names AEROSIL 200V, AEROSIL (registered trademark), SYLOPHO BIC 100 (FUJI SILYSIA, inc.), NIPSIL E220A (NIPPON SILICA industry (manufactured by Japanese company Co., ltd.), and ADMATINE (registered trademark) SO ADMATECHS, etc.

The shape of the particles is not particularly limited, and amorphous, needle-like, flat, spherical, or the like may be used, and particularly when spherical particles are used, the transparency of the resulting film roll can be improved, and thus it is preferable.

Since the particle size is smaller than the wavelength of visible light because the light is scattered and the transparency is poor when the particle size is close to the wavelength of visible light, the particle size is preferably 1/2 or less of the wavelength of visible light.

If the particle size is too small, the slidability may not be improved, and thus it is particularly preferably in the range of 80 to 180 nm.

The size of the particles refers to the size of aggregates when the particles are aggregates of primary particles.

In the case where the particles are not spherical, the diameter of a circle corresponding to the projected area thereof is referred to.

The fine particles are added in the range of 0.05 to 10 mass%, preferably 0.1 to 5 mass%, relative to the base resin.

4. Polarizing plate

A part of the film roll of the present invention can be suitably used by being provided in a polarizing plate.

The polarizing plate is generally composed of a polarizing film (also referred to as "polarizing film") and transparent resin films laminated on both surfaces thereof, and a part of the film roll of the present invention may be provided as the resin film in the polarizing plate, for example.

Examples of the polarizer include a polarizer having a structure in which a polarizer layer is formed using a polarizer film, a polarizer protective film is formed using a resin film, and an adhesive layer is disposed between the polarizer protective film and the polarizer protective film.

(4.1) polarizer layer

The polarizer layer is a layer at least comprising a polarizer film.

Here, the term "polarizer" refers to an element that passes only light having a polarization plane in a predetermined direction.

Examples of the polarizing film include a polyvinyl alcohol-based polarizing film and a cellulose ester-based polarizing film, but a polyvinyl alcohol-based resin is preferable because it is superior to a cellulose ester-based resin in transparency, optical characteristics, durability, and the like.

Examples of the polyvinyl alcohol-based polarizing film include a film obtained by dyeing a polyvinyl alcohol-based film with iodine and a film obtained by dyeing a polyvinyl alcohol-based film with a dichroic dye.

The polyvinyl alcohol-based polarizing film may be a film obtained by uniaxially stretching a polyvinyl alcohol-based film and then dyeing it with iodine or a dichroic dye (preferably a film further subjected to a durability treatment with a boron compound), or may be a film obtained by uniaxially stretching a polyvinyl alcohol-based film and then dyeing it with iodine or a dichroic dye (preferably a film further subjected to a durability treatment with a boron compound).

The absorption axis of the polarizer layer is generally parallel to the direction of maximum stretching.

For example, an ethylene-modified polyvinyl alcohol 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-A2003-248123, JP-A2003-342322 and the like can be used.

The thickness of the polarizer layer is preferably 5 to 30. Mu.m, more preferably 5 to 20. Mu.m, from the viewpoint of reducing the thickness of the polarizing plate.

(4.2) polarizer protective film

A part of the film roll of the present invention may be disposed on at least one surface (at least the surface facing the liquid crystal cell) of the polarizer layer, and may be used as a polarizer protective film or a retardation film.

The surface of the polarizer protective film on which the polarizer layer is laminated may be subjected to an activation treatment described later.

In the case where a part of the film roll of the present invention is disposed as a polarizer protective film on only one surface of the polarizer layer, another optical film such as a retardation film may be disposed on the other surface of the polarizer layer.

Examples of other optical films include: commercially available cellulose ester films (e.g., kenicamantadine TAC KC8UX, KC5UX, KC4UX, KC8UCR3, KC4SR, KC4BR, KC4CR, KC4DR, KC4FR, KC4KR, KC8UY, KC6UY, KC4UE, KC 8UY-HA, KC2UA, KC4UA, KC6UA, KC8UA, KC2UAH, KC4UAH, KC6UAH, manufactured by Kenicamantadine (Co., ltd.), FUJITACT40UZ, FUJITACT60UZ, FUJITACT80UZ, FUJITACTD80UL, FUJITACTD60UL, FUJITACTD40UL, FUJITACR02, FUJITACR06, manufactured by FUJITILM (Co., ltd.), etc.).

The thickness of the other optical film may be, for example, 5 to 100. Mu.m, preferably 40 to 80. Mu.m.

(4.3) adhesive layer

The adhesive layer is formed by drying an aqueous adhesive or an ultraviolet-curable adhesive disposed between a part of the film (or other optical film) of the film roll of the present invention and the polarizer layer.

The thickness of the adhesive layer may be, for example, about 0.01 to 10. Mu.m, preferably about 0.03 to 5. Mu.m.

(aqueous adhesive)

Examples of aqueous adhesives include: vinyl, gelatin, vinyl latex, polyurethane, isocyanate, polyester, epoxy, and the like.

In the case of using a polyvinyl alcohol-based polarizing film for the polarizer layer, an aqueous adhesive containing a vinyl-based resin is preferable from the viewpoint of easy adhesion, and an aqueous adhesive containing a polyvinyl alcohol-based resin (fully saponified polyvinyl alcohol aqueous solution, etc.) is more preferable.

The aqueous adhesive containing the polyvinyl alcohol resin may further contain a water-soluble crosslinking agent such as boric acid, borax, glutaraldehyde, melamine, oxalic acid, and the like.

(ultraviolet-curable adhesive)

The ultraviolet curable adhesive may be a photo radical polymerizable composition or a photo cation polymerizable composition.

Among them, a photo cation polymerizable composition is preferable.

The photo cation polymerizable composition contains an epoxy compound and a photo cation polymerization initiator.

The epoxy compound is a compound having 1 or more, preferably 2 or more epoxy groups in the molecule.

Examples of the epoxy compound include: hydrogenated epoxy compounds (glycidyl ethers of alicyclic polyols) obtained by reacting epichlorohydrin with alicyclic polyols; aliphatic epoxy compounds such as polyglycidyl ethers of aliphatic polyols or alkylene oxide adducts thereof; alicyclic epoxy compounds having 1 or more epoxy groups bonded to an alicyclic ring in the molecule.

The epoxy compound may be used alone or in combination of two or more.

The photo-cationic polymerization initiator may be, for example, an aromatic diazonium salt; onium salts such as aromatic iodonium salts and aromatic sulfonium salts; iron-arene complexes, and the like.

The photo-cationic polymerization initiator may further contain additives such as cationic polymerization accelerators such as oxetanes and polyols, photosensitizers, solvents and the like, as required.

(4.4) method for producing polarizing plate

The method for manufacturing a polarizing plate of the present invention comprises: 1) A step of activating the surface of the polarizer protective film; 2) Laminating a polarizer layer (polarizing film) on the surface of the polarizer protective film subjected to the activation treatment via an aqueous adhesive or an ultraviolet-curable adhesive; 3) And drying the obtained laminate.

Procedure 1)

The surface of the polarizer protective film (the surface to be bonded to the polarizer layer) is subjected to an activation treatment.

This facilitates adhesion to the polarizer layer.

Specifically, the polarizer protective film and the polarizer layer are easily bonded by hydrophilizing the siloxane bond, ether bond, tertiary carbon atom, etc. of the side chain of the specific graft polymer contained in the polarizer protective film by the activation treatment to improve the affinity with the aqueous adhesive or to facilitate the interaction.

Examples of the activation treatment include: corona treatment, plasma treatment, and saponification treatment, preferably corona treatment and plasma treatment, more preferably corona treatment.

The activation treatment conditions may be those which can sufficiently activate siloxane bonds, ether bonds, tertiary carbon atoms, and the like contained in the side chains of the specific graft polymer.

When the activation treatment is corona treatment, the irradiation amount is preferably 100 to 1000[ W.min/m ] ² ]More preferably in the range of 150 to 900[ W.min/m ] ² ]Within a range of (2).

Procedure 2)

Next, a polarizer layer is laminated on the surface of the polarizer protective film subjected to the activation treatment via an aqueous adhesive or an ultraviolet curable adhesive.

Procedure 3)

Subsequently, the obtained laminate was dried to obtain a polarizing plate.

Drying may be performed by heat drying.

The drying temperature may be in the range of 60 to 100℃as long as the aqueous adhesive or the ultraviolet curable adhesive is sufficiently dried.

5. Display device

A part of the film roll of the present invention can be suitably used by being provided in a display device.

The display device may be: various image display devices such as liquid crystal display devices and organic EL display devices.

Hereinafter, a case where a polarizer and a liquid crystal display device are provided as a polarizer protective film will be described as an example of the use of a part of the film roll of the present invention.

(5.1) liquid Crystal display device

Specifically, the display device of the present invention includes, for example, a liquid crystal display device including a liquid crystal cell and a pair of polarizing plates sandwiching the liquid crystal cell.

Fig. 16 is a schematic diagram showing an example of the configuration of a liquid crystal display device of the present invention.

As shown in fig. 16, the liquid crystal display device (200) includes: a liquid crystal cell (220), a 1 st polarizing plate (210) and a 2 nd polarizing plate (230) which sandwich the liquid crystal cell (220), and a backlight (240).

The display mode of the liquid crystal cell (220) may be, for example, STN, TN, OCB, HAN, VA (MVA, PVA), IPS or other various display modes, and in order to obtain a high contrast, the VA (MVA, PVA) mode is preferable.

The 1 st polarizing plate (210) comprises: a 1 st polarizer (212), a polarizer protective film (211) disposed on the surface of the 1 st polarizer (212) opposite to the liquid crystal cell, and a polarizer protective film (213) disposed on the surface of the 1 st polarizer (212) on the liquid crystal cell side.

The 2 nd polarizer (230) includes: a 2 nd polarizer (232), a polarizer protective film (231) disposed on the surface of the 2 nd polarizer (232) on the liquid crystal cell side, and a polarizer protective film (233) disposed on the surface of the 2 nd polarizer (232) on the opposite side of the liquid crystal cell. One of the polarizer protective films (213) and (231) may be omitted as needed.

Also, at least one of the polarizer protective films (211) and (233) may be the resin film of the present invention.

(5.2) other uses

The film roll of the present invention may be used as a protective film for an image display device such as an image display device including a touch panel, an organic EL display, or a plasma display, as well as a polarizer protective film for a liquid crystal display device.

The embodiment to which the present invention can be applied is not limited to the above-described embodiment, and may be modified as appropriate within the scope not departing from the gist of the present invention.

Examples (example)

The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto. In the examples, "part" or "%" is used, and unless otherwise specified, "part by mass" or "% by mass" is indicated. "

[ preparation of A film roll ]

[ A.1 preparation of film roll No. 1]

The film was formed by a solution casting film forming method.

(dopant production Process [ S1 ])

Synthesis of cyclic polyolefin Polymer [ P-1]

100 parts by mass of purified toluene and 100 parts by mass of norbornene carboxylic acid methyl ester were charged into a stirring apparatus.

Subsequently, 25m mol% (based on the mass of the monomer) of ethylhexanoate-Ni dissolved in toluene, 0.225 mol% (based on the mass of the monomer) of tris (pentafluorophenyl) boron, and 0.25 mol% (based on the mass of the monomer) of triethylaluminum dissolved in toluene were charged into a stirring apparatus.

It was allowed to react at room temperature for 18 hours under stirring.

After the completion of the reaction, the reaction mixture was poured into an excessive amount of ethanol to form a polymer precipitate.

The polymer obtained by refining the precipitate was dried in vacuum drying at 65℃for 24 hours, thereby synthesizing a cyclic polyolefin polymer [ P-1].

Preparation of cyclic polyolefin solution (dope [ D-1 ]) ]

The following composition [1] was put into a mixing tank, stirred to dissolve each component, and then filtered through a filter paper having an average pore diameter of 34 μm and a sintered metal filter having an average pore diameter of 10 μm to prepare a cyclic polyolefin solution (dope [ D-1 ]).

Composition [1]

25 parts by mass of a cyclic polyolefin polymer [ P-1]

Dichloromethane 65 parts by mass

Ethanol 10 parts by mass

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.

Composition [2]

4 parts by mass of fine particles (AEROSIL R812: manufactured by NIPPON AEROSIL Co., ltd., primary average particle diameter: 7nm, apparent specific gravity 50 g/L)

Dichloromethane 76 parts by mass

20 parts by mass of ethanol

Preparation of dope for film Forming [1]

A dope [1] for film formation (resin composition cycloolefin resin: COP) was prepared by mixing 100 parts by mass of the above-mentioned cyclic polyolefin solution (dope [ D-1 ]) with 0.75 part by mass of the fine particle dispersion [1].

(casting Process [ S2 ])

The dope [1] for film formation (cycloolefin resin of resin composition: COP) prepared in the dope preparation step [ S1] was fed to a casting die by a pressure type quantitative gear pump using a pipe, the dope was cast from the casting die at a casting position on a support made of a rotary-driven stainless steel endless belt, which was infinitely transferred, by a film-forming line, in a width of 1800mm, and the dope was heated on the support until the dope was self-supporting, and the solvent was evaporated until the cast film was peeled from the support by a peeling roller, whereby it was dried to form a cast film.

(stripping step [ S3 ])

In the casting step [ S2], after the casting film is formed, the casting film is peeled from the support by a peeling roller in a state of having self-supporting property.

(shrinkage step [ S4 ])

The film was subjected to a high temperature treatment in a state where the width of the film was not maintained, and the film was contracted at a contraction rate of 7% in the broadside direction by increasing the density of the film.

(1 st drying step [ S5 ])

Then, the film is heated on the support to evaporate the solvent.

The residual solvent content of the film was measured by the following method and found to be 5 mass% or less.

Determination of residual solvent amount

The residual solvent amounts were analyzed by gas chromatography as follows.

That is, the membrane is provided at an arbitrary position, and the vial is ensured to be sealed promptly in order to prevent the solvent remaining in the membrane from evaporating.

Next, a needle was inserted into the vial, and mass spectrometry was performed using a gas chromatograph (AGILENT TECHNOLOGIE S (manufactured by co.) ed).

The amount of residual solvent is defined by the following formula.

Residual solvent amount [ mass% ] = { (M-N)/N } ×100

In the formula, M is the mass [ g ] of a sample taken at any time point during or after the production of a cast film or film, and N is the mass [ g ] of the sample after heating at 115℃for 1 hour.

(1 st stretching step [ S6 ])

Then, the film was conveyed in a tenter stretching apparatus and subjected to transverse stretching.

(1 st cutting step [ S7 ])

Both ends of the stretched film in the widthwise direction are cut.

(2 nd stretching step [ S8 ])

The film was stretched by a tenter stretching apparatus in the same manner as in the 1 st stretching step.

The residual solvent content of the film was measured by the above method and found to be 1 to 5 mass%.

(2 nd cutting step [ S9 ])

The two ends of the stretched film in the widthwise direction are cut in the same manner as in the 1 st cutting step.

(2 nd drying step [ S10 ])

In the same manner as in the 1 st drying step, the film is heated on the support to evaporate the solvent.

The residual solvent content of the film was measured by the above method and found to be 0.1 to 2 mass%.

(3 rd cutting step [ S11 ])

The two ends of the stretched film in the widthwise direction are cut in the same manner as in the 1 st cutting step and the 2 nd cutting step.

(winding step [ S12 ])

The film was wound at a winding speed (linear speed of film transport) of 60m/min at a film roll width of 2000mm and a roll length of 10000 m.

The thickness of the film at the time of winding was measured and found to be 40. Mu.m.

The winding device and TR (touch roll) were used to adjust the touch pressure at the peripheral portion of the winding core to 15.2N/m, the tension to 40N/m, the touch pressure at the central portion of the winding to 16.0N/m, the tension to 40N/m, the touch pressure at the peripheral portion of the winding to 16.0N/m, and the tension to 40N/m, and the taper (the case and the corner) was 70% and 25%.

The thickness of the film was measured 1612 by a series phase retardation/film thickness measuring device RE-200L 2T-rth+film thickness (OTSUK A ELECTRONICS, manufactured by the company corporation), and the difference in height between the highest portion and the lowest portion of the uneven structure formed on the surface of the film was calculated as the average value.

At this time, the traverse speed was 100 mm/sec.

Through the above steps, film roll number 1 was prepared.

[ A.2 preparation of film roll numbers 2 to 13 ]

In the dope production process [ S1], film roll numbers 2 to 13 were produced in the same manner as in the film roll number 1, except that the type of dope (resin composition) for film production, the roll length [ m ], the roll speed [ m/min ], the thickness [ μm ] of the film, the touch pressure [ N/m ] and the tension [ N/m ] in the peripheral portion of the roll core at the time of winding, the touch pressure [ N/m ] and the tension [ N/m ] in the central portion of the roll, and the touch pressure [ N/m ] and the tension [ N/m ] in the peripheral portion of the roll were changed as shown in Table I in the winding process [ S12 ].

[ calculation of the thickness of the void layer in the core peripheral portion, the roll center portion, and the roll outer peripheral portion ]

After each film roll was stored at 40 ℃ and 80% rh for 1 week, the thickness of the void layer in the roll core peripheral portion, the roll center portion, and the roll outer peripheral portion was calculated as described above (an example of a method of calculating the thickness of the void layer).

A specific method of calculating the thickness of the void layer in the peripheral portion of the winding core using the film roll number 1 is shown below.

At a position (P) at which the roll diameter of the widthwise side surface portion of the film roll No. 1 after 1 week of storage was 20% ₂₀ ) The image data is obtained by photographing the side surface portion as a center, and the edge emphasis processing is performed on the obtained image data to obtain a processed image for calculating the thickness of the void layer as shown in fig. 3.

Then, the center (P ₂₀ ) The radial length was measured from the point located at the 100 th layer position perpendicular to the film surface toward the outside of the roll as the starting point, and the thickness X [ mu ] m of the void layer in the peripheral portion of the roll core was calculated using the following formula (A)]。

When the measured values are substituted, the thickness X [ μm ] = [4021 μm-40.00 μm×100] ++100=0.21 μm of the void layer of film roll number 1.

The thickness of the void layer in the central portion of the roll was set at a position (P) at which the roll diameter of the side portion in the width direction was 50% ₅₀ ) As a center, the side portion is photographed to process the center (P ₅₀ ) Except for the starting point, the thickness of the void layer in the peripheral portion of the winding core was calculated in the same manner.

The thickness of the void layer at the outer peripheral portion of the roll was set at a position (P) at which the roll diameter of the side portion in the width direction was 80% ₈₀ ) As a center, the side portion is photographed to process the center (P ₈₀ ) Except for the starting point, the thickness of the void layer in the peripheral portion of the winding core was calculated in the same manner.

[ C evaluation ]

[ evaluation of the extent of transfer by C.1 tape ]

(evaluation method)

The film of each film roll after 1 week of storage was unwound, and the position in the longitudinal direction of the film displayed in the winding device from the core portion to several meters was measured using a tachometer for the transfer of the tape in which the deformation in the width direction was clearly seen, and the evaluation was performed based on the following evaluation criteria. The results are shown in Table I.

(evaluation criterion)

O: tape transfer occurs only from the core portion to less than 20m.

Delta: the tape transfer occurs from the core portion to 20m or more and less than 50 m.

X: the tape transfer occurs from the core portion to 50m or more.

[ evaluation of the degree of chain deformation of C.2 ]

(evaluation method)

The film of each film roll after 1 week of storage was unwound, and the position value in the longitudinal direction of the film displayed on each winding device was measured for the length [ m ] of the film in which the chain-like deformation was generated using a tachometer, and the evaluation was performed based on the following evaluation criteria.

If Δ is equal to or greater than the below-described evaluation criterion, it is determined that there is no problem in practice. The results are shown in Table I.

(evaluation criterion)

And (3) the following materials: the length of the film subjected to chain deformation is less than 10m.

O: the length of the film deformed in a chain shape is 10m or more and less than 50m.

Delta: the length of the film deformed in a chain shape is 50m or more and less than 200m.

X: the length of the film deformed in a chain shape is 200m or more.

[ D summary ]

As is clear from the conditions, evaluation results, and the like shown in table I, the evaluation of the degree of tape transfer and the degree of chain deformation was higher in the examples of the present invention than in the comparative examples, and the results were excellent from a comprehensive point of view.

[ description of symbols ]

1. 1a stirring device (stirring tank)

2. Casting die

3. Support (Ring belt, roller)

3a, 3b roller

4. Stripping roller

5. Cast film

6. Drying device

7. Stretching device (tenter stretching device, oblique stretching device)

8. Cutting part

9. Stretching device (tenter stretching device)

10. Cutting part

11. Drying device

12. Cutting part

13. Winding device

14. Extrusion machine

15. Casting die

16. Casting roller and support

16a touch roller

17. Cooling roller

19. Stretching device (tenter stretching device)

20. Cutting part

21. Stretching device (tenter stretching device)

22. Cutting part

23. Winding device

30. Film roll

31. Film and method for producing the same

32. Roller

33. Touch roller

40. Stretching device (tenter stretching device)

42. Clamp

46. Cover for vehicle

48. Endless chain

50. Driving sprocket

52. Driven sprocket

54. Rail track

56. Opening part

60. Total reflection mirror

61. Half mirror

62. Telecentric lens

63. High brightness line illumination

64. Single color line sensor-camera

80. Temperature distribution sensor

101. Nozzle fixing portion

102. Nozzle

103. Cast film

104. End nozzle

105. Central nozzle

106. Clamp cover

200. Liquid crystal display device having a light shielding layer

210. 1 st polarizer

211. Polarizer protective film disposed on surface of 1 st polarizer opposite to liquid crystal cell side

212. 1 st polarizer

213. Polarizer protective film disposed on liquid crystal cell side surface of 1 st polarizer

220. Liquid crystal cell

230. 2 nd polarizer

231. Polarizer protective film disposed on liquid crystal cell side surface of 2 nd polarizer

232. 2 nd polarizer

233. Polarizer protective film disposed on surface of the 2 nd polarizer opposite to the liquid crystal cell side

240. Backlight source

A roll core peripheral part

Center part of the roll B

Outer peripheral portion of C coil

F film

H _A 、H _B Width of (L)

Q thermocouple, infrared (IR) heater

E shooting device

R coil core

Broadside direction of TD film roll

U shooting unit

Any point on the broadside direction side surface of the P film roll

S film roll measured surface (broadside direction side surface)

S ₀ Surface of winding core

S ₁ Layer of film attached to surface of winding core

S ₂ Layer of film that borders the periphery of the roll core and the roll center

S ₃ Layer of film that borders roll center portion and roll outer peripheral portion

S ₄ The outermost film layer of the film roll

P ₂₀ 20% of the roll diameter

P ₅₀ Position with 50% roll diameter

P ₈₀ 80% of the roll diameter

Claims

1. A film roll having no knurled processing portion, wherein,

when the thickness of the gap layer between the films adjacent to each other in the peripheral portion of the winding core measured on the side face portion in the width direction of the film winding is X [ mu ] m, and the thickness of the gap layer between the films adjacent to each other in the outer peripheral portion of the winding is Y [ mu ] m, the X and Y satisfy the relationship of the following formula (1),

formula (1): y < X.

2. The roll of film of claim 1 wherein,

the X [ mu ] m and the Y [ mu ] m satisfy the following formula (2) and the following formula (3),

formula (2): 0.05< Y <0.50

Formula (3): 1< (X/Y) <3.

3. A method for producing a film roll, which is a method for producing a film roll having no knurled portion, wherein,

when the thickness of the gap layer between the films adjacent to each other in the peripheral portion of the winding core measured on the side face portion in the width direction of the film winding is X [ mu ] m, and the thickness of the gap layer between the films adjacent to each other in the outer peripheral portion of the winding is Y [ mu ] m, the thickness is adjusted so that the X and the Y satisfy the relation of the following formula (1),

Formula (1): y < X.

4. The method for producing a film roll according to claim 3, wherein,

is adjusted in such a manner that the X [ mu ] m and the Y [ mu ] m satisfy the following formula (2) and the following formula (3),

formula (2): 0.05< Y <0.50

Formula (3): 1< (X/Y) <3.

5. The method for producing a film roll according to claim 3 or 4, wherein,

the film touch pressure at the peripheral portion of the winding core is adjusted to be in the range of 2 to 30[ N/m ], the film touch pressure at the central portion of the winding is adjusted to be in the range of 3 to 40[ N/m ], and the film touch pressure at the peripheral portion of the winding is adjusted to be in the range of 5 to 55[ N/m ].

6. A polarizing plate is provided with:

a portion of the film of claim 1 or 2.

7. A display device is provided with:

a portion of the film of claim 1 or 2.