WO2021201209A1

WO2021201209A1 - Laminate film, polarizing plate, display device, and method for manufacturing polarizing plate roll

Info

Publication number: WO2021201209A1
Application number: PCT/JP2021/014133
Authority: WO
Inventors: 隆建部; 大久保　康
Original assignee: コニカミノルタ株式会社
Priority date: 2020-04-02
Filing date: 2021-04-01
Publication date: 2021-10-07
Also published as: CN115280201A; JPWO2021201209A1; KR20220127320A

Abstract

The present invention has the object of providing a laminate film that is a thin film but that can be handled in the same manner as a conventional polarizing plate protective film, further has excellent drying properties, dimensional stability, and curl control performance during polarizing plate processing, and has improved productivity with regard to polarizing plate processing; the present invention also has the object of providing a polarizing plate equipped with this laminate film, a high-quality display device having no light leakage or optical unevenness, and a method for manufacturing a polarizing plate roll. This laminate film is formed by laminating at least a detachable functional layer on a base material film, and is characterized in that the layer thickness of the functional layer is in a range of 1-19 μm, the moisture permeability of the base material film at a temperature of 40°C and humidity of 90% RH is in a range of 100-400 g/m2·24h, the maximum dimensional change rate in the film plane of the base material film at a temperature of 23°C and humidity of 20-80% RH is in a range of 0.01-0.10%, and the thickness of the base material film is in a range of 20-60 μm.

Description

Method for manufacturing laminated film, polarizing plate, display device and polarizing plate roll

The present invention relates to a method for manufacturing a laminated film, a polarizing plate, a display device, and a polarizing plate roll. More specifically, although it is a thin film, it can be handled in the same manner as a conventional polarizing plate protective film, and further has excellent drying property, dimensional stability, and curl controllability during polarizing plate processing, and is a polarizing plate. Regarding laminated films and the like with improved processing productivity.

Since the liquid crystal display device has low power consumption and can be made thinner, it is widely used as an image display device for televisions (TVs), personal computers (PCs), and the like.

In recent years, there has been a demand for larger and thinner televisions and improved display quality, and in order to suppress optical unevenness caused by stress caused by bending of display panels and dimensional changes of members, thinning of members has been made. It has been demanded.

Furthermore, in applications such as notebook type and small and medium-sized personal computers, smartphones, slate PCs, etc., there is a particularly high demand for thinning of members, and functional films used (for example, viewing angle compensation film, polarizing plate protective film, etc.) Further thinning is required.

When handling a thin film, there is a concern that problems such as wrinkles, wrinkles, and breakage may occur during film transportation, so it is common to handle by laminating a protective film. For example, in the polarizing plate processing step, when the functional film and the polarizing element layer are bonded and then dried, the protective film is peeled off and dried, and then the protective film is reattached and handled from the viewpoint of scratch resistance. Since the process becomes complicated, it is required to be more simplified.

Patent Document 1 describes a method of forming a base resin film and a functional film as a laminated film in order to handle a thin functional film, and a polarizing plate is processed using the laminated film. At that time, there was a problem that the polarizing plate curled due to high moisture permeability and a large change in humidity dimension, and it was difficult to handle. Further, if the polarizing plate is curled due to humidity fluctuation after being incorporated in the display device, there is a problem that the curl causes light leakage and optical unevenness (also referred to as “bend unevenness”), which impairs the display quality.

On the other hand, when a member having low moisture permeability is used, the drying property is poor and the productivity is lowered in the step of bonding to the polarizing element layer which is a polarizing plate constituent member by using an adhesive or an adhesive. There is a problem that the polarizer layer is deteriorated by applying heat in a water-containing state.

Japanese Unexamined Patent Publication No. 2013-134336

The present invention has been made in view of the above problems and situations, and the problem to be solved is that although it is a thin film, it can be handled in the same manner as a conventional polarizing plate protective film without involving a complicated process. Furthermore, a laminated film having excellent drying property, dimensional stability, and curl controllability during polarizing plate processing and improved productivity of polarizing plate processing, a polarizing plate equipped with the laminated film, and high height without light leakage and optical unevenness. The purpose of the present invention is to provide a high-quality display device and a method for manufacturing a polarizing plate roll.

In order to solve the above problems, the present inventor has laminated a removable functional layer having a specific layer thickness on a base film having a specific film thickness in the process of examining the cause of the above problem. By controlling the moisture permeability and humidity dimensional change rate of the base film within a specific range, a laminated film having excellent drying property, dimensional stability, and curl controllability during polarizing plate processing can be obtained. Furthermore, it has been found that optical unevenness due to light leakage and bend deformation of the liquid crystal display device can be suppressed by using a polarizing plate provided with the laminated film as a polarizing plate protective film.

That is, the above problem according to the present invention is solved by the following means.

1. 1. A laminated film in which at least a peelable functional layer is laminated on a base film.
The layer thickness of the functional layer is in the range of 1 to 19 μm.
Temperature 40 ° C. of the substrate film, the moisture permeability under humidity of 90% RH is in the range of ^{100 ~ 400g / m 2 · 24h} ,
The maximum dimensional change rate in the film surface in the temperature range of 23 ° C. and the humidity range of 20 to 80% RH of the base film is in the range of 0.01 to 0.10%, and
A laminated film characterized in that the film thickness of the base film is in the range of 20 to 60 μm.

2. The laminated film according to item 1, wherein the thickness of the functional layer is in the range of 2 to 10 μm.

3. The first item or the first item, wherein the base film contains any one of a cycloolefin resin, a polyarylate resin, a styrene / (meth) acrylate copolymer, and a styrene / hydroxystyrene copolymer. Item 2. The laminated film according to item 2.

4. A polarizing plate comprising the laminated film according to any one of items 1 to 3.

5. A display device comprising the laminated film according to any one of items 1 to 3 or the polarizing plate according to item 4.

6. A method for producing a polarizing plate roll, wherein the laminated film according to any one of items 1 to 3 is wound around at least one surface of a polarizing element layer while being bonded to at least one surface via an adhesive. A polarizing plate roll including a step of winding the laminated film while adhering the laminated film to the polarizing layer so that the layers of the polarizing layer, the adhesive layer, the functional layer and the base film are arranged in this order from the inside of the roll. Manufacturing method.

By the above means of the present invention, although it is a thin film, it can be handled in the same manner as a conventional polarizing plate protective film without involving a complicated process, and further, excellent drying property and dimensional stability during polarizing plate processing. , And a laminated film having curl controllability and improved productivity of polarizing plate processing, a polarizing plate equipped with the laminated film, a high-quality display device having no optical unevenness due to light leakage or bend deformation, and a polarizing plate roll. A method can be provided.

The mechanism of expression or mechanism of action of the effect of the present invention has not been clarified, but it is inferred as follows.

The present invention is a laminated film in which a removable functional layer having a specific layer thickness is laminated on a base film having a specific film thickness, and the moisture permeability and the rate of change in humidity dimension of the base film are specified. By controlling within the above range, it is possible to provide a laminated film that has excellent drying property, dimensional stability, and curl controllability at the time of polarizing plate processing and can be applied to a polarizing plate protective film.

That is, by controlling the moisture permeability of the base film within a specific range, the drying property during polarizing plate processing is controlled to improve the adhesiveness, and the dimensional change rate with respect to humidity fluctuation is reduced to reduce the thin film. It is possible to suppress wrinkles and curl deformation of the functional layer. Therefore, the polarizing plate can be processed by the same polarizing plate processing process as the conventional one without reducing the productivity and without requiring the complicated processing process as described above using the protective film, and further, the polarizing plate curl can be formed. Since it can be suppressed, it is presumed that it is possible to provide a high-quality display device without light leakage or optical unevenness when it is provided in the display device.

This is because when the moisture permeability of the base film and the change in humidity dimension are within a specific range, the water content in the polarizing element layer does not continue to remain in the polarizing plate processing step and does not suddenly escape. Since it is possible to induce appropriate volatility, it is possible to suppress deterioration of the polarizer layer due to residual moisture during heating during drying, and it is thought that curl generation due to sudden changes in moisture can be suppressed. .. It is presumed that by using the polarizing plate produced in this manner and the polarizing plate in the display device, it is possible to provide a high-quality display device without light leakage or optical unevenness due to humidity fluctuation.

Schematic diagram showing a cross section of the laminated film of the present invention The figure which showed typically the example of the dope preparation step, the casting step and the drying step (solvent evaporation step) of the solution casting method. The schematic diagram which shows the manufacturing method of the laminated film which concerns on one Embodiment of this invention Cross-sectional view of polarizing plate with base film Cross-sectional view of the polarizing plate from which the base film has been peeled off

The laminated film of the present invention is a laminated film in which at least a peelable functional layer is laminated on a base film, and the layer thickness of the functional layer is in the range of 1 to 19 μm, and the base material. temperature 40 ° C. of the film, the moisture permeability under humidity of 90% RH is in the range of ^{100 ~ 400g / m 2 · 24h} , temperature 23 ° C. of the base film, in the region of RH humidity 20-80%, the film The maximum in-plane dimensional change rate is in the range of 0.01 to 0.10%, and the film thickness of the base film is in the range of 20 to 60 μm. This feature is a technical feature common to or corresponding to the following embodiments.

As an embodiment of the laminated film of the present invention, from the viewpoint of exhibiting the effect of the present invention, the layer thickness of the functional layer is in the range of 2 to 10 μm to prevent wrinkles and curl deformation of the functional layer which is a thin film. It is preferable from the viewpoint of suppressing and providing a thinner polarizing plate when the base film is peeled off and the functional layer is bonded to the polarizer layer. Further, it is also preferable from the viewpoint of suppressing optical unevenness of the liquid crystal display device using the polarizing plate.

The base film is based on a resin material selected from a cycloolefin resin, a polyarylate resin, a styrene / (meth) acrylate copolymer, or a styrene / hydroxystyrene copolymer. By controlling the moisture permeability of the material film within a specific range, the dryness during styrene processing is improved, and by reducing the dimensional change rate with respect to humidity fluctuations, the occurrence of wrinkles and curls in the functional layer is suppressed. From the viewpoint of Furthermore, by using the above resin material, it can be preferably used from the viewpoint of processability when processing the functional layer on the base film.

The polarizing plate of the present invention is provided with the laminated film of the present invention, so that the polarizing plate can be processed by the same polarizing plate processing process as the conventional one without reducing the productivity and without requiring a complicated processing process.

By providing the laminated film of the present invention or the polarizing plate, the display device of the present invention improves the curl resistance of the polarizing plate to suppress light leakage, and further, the layer thickness of the functional layer is in the range of 1 to 19 μm. It is preferable from the viewpoint of obtaining a high-quality display device having no optical unevenness.

In the method for producing a polarizing plate roll of the present invention, the laminated film is wound around the polarizing layer so as to be in the order of the polarizer layer, the adhesive layer, the functional layer, and the substrate fill from the inside of the roll. It is characterized by including a process. Depending on the method for manufacturing the polarizing plate roll, the base film can also serve as a protective film, leading to a reduction in the number of parts and a simplification of the processing process.

Hereinafter, the present invention, its constituent elements, and modes and modes for carrying out the present invention will be described in detail. In the present invention, "-" is used to mean that the numerical values described before and after the value are included as the lower limit value and the upper limit value.

<< Overview of the Laminated Film of the Present Invention >>
The laminated film of the present invention is a laminated film in which at least a peelable functional layer is laminated on a base film, and the layer thickness of the functional layer is in the range of 1 to 19 μm, and the base material. temperature 40 ° C. of the film, the moisture permeability under humidity of 90% RH is in the range of ^{100 ~ 400g / m 2 · 24h} , temperature 23 ° C. of the base film, in the region of RH humidity 20-80%, the film The maximum in-plane dimensional change rate is in the range of 0.01 to 0.10%, and the film thickness of the base film is in the range of 20 to 60 μm.

(Humidity permeability)
In the present invention, the moisture permeability of the base film is based on the calcium chloride-cup method described in JIS Z-0208: 1976, and the film to be measured is left to stand for 24 hours under the conditions of a temperature of 40 ° C. and a humidity of 90% RH. It is a value measured by.

Moisture permeability of the base film according to the present invention is in the range of ^{100 ~ 400g / m 2 · 24h} , preferably in the range of ^{100g ~ 300 / m 2 / 24h} , 100 ~ 200g / m 2 / more preferably 24h in the range of, more preferably within the range of ^{100 ~ 150g / m 2 · 24h} .

If the moisture permeability is less than 100g / m ² · 24h, a substrate film or a functional layer according to the present invention, drying properties and adhesion inferior in bonding the polarizer layer with water glue, etc., more The addition of heat in the presence of residual moisture may cause deterioration of the polarizer layer, resulting in deterioration of display quality. On the other hand, when the moisture permeability is more than 400g / m ² · 24h, causing polarizer curl by dehydration shrinkage of the polarizer layer due to sudden drying, even may cause peeling of a laminated film.

Specifically, the moisture permeability of the base film is measured according to JIS Z 0208: 1976 after being left in an environment of a temperature of 40 ° C. and a humidity of 90% RH for 24 hours as described above.

As described above, the the lower limit value of the moisture permeability of the substrate film was set to 100g / m ² · 24h is a limit Mizunori drying is good, the upper limit was set to 400g / m ² · 24h Is the limit value of the polarizing plate curl due to the sudden dehydration shrinkage of the polarizing element layer, so that the moisture permeability of the base film according to the present invention is adjusted within the above range.

(Dimensional change rate)
In the present invention, the maximum dimensional change rate in the film surface in the range of the temperature of the base film of 23 ° C. and the humidity of 20 to 80% RH is in the range of 0.01 to 0.10%.

Here, the "dimensional change rate" of the present invention is a value calculated as follows.

Two cross-shaped marks are placed on the surface of the base film, and the base film is left for 24 hours in an environment of a temperature of 23 ° C. and a humidity of 20% RH to control the humidity, and then between the two marks with an optical microscope. Measure the distance L _1. After that, the film was left to stand in an environment of a temperature of 23 ° C. and a humidity of 80% RH for 24 hours to adjust the humidity, and then the distance L ₂ between the two marks was measured in the same manner, and the dimensional change rate (%) was calculated by the following formula. do.

Dimensional change rate (%) = {(L _2- L ₁ ) / L ₁ } x 100
The "maximum dimensional change rate in the film surface" as used in the present invention means that the two places on the film surface are marked with a cross-shaped mark at random at 10 places in the film surface, and the dimensional change rate is calculated. The value indicating the maximum dimensional change rate among each measurement is adopted.

If the dimensional change rate is less than 0.01%, poor adhesion between the polarizing element layer and the functional layer occurs, and if it exceeds 0.10%, the functional layer is wrinkled or curled, and the polarizing plate curl is formed. As a result, the display panel is warped, resulting in light leakage and optical unevenness. More preferably, it is in the range of 0.03 to 0.08%.

(Layer structure of laminated film)
FIG. 1 shows an example of the layer structure of the laminated film of the present invention.

The laminated film 1 of the present invention has a base film 2 and a functional layer 3 on the base film 2. The base film 2 and the functional layer 3 may be formed by laminating a plurality of layers. Further, the functional layer 3 may have another functional layer such as a primer layer (not shown) or a protective layer (not shown) on the front surface or the back surface.

The base film 2 may have an adhesive layer (not shown) or an adhesive layer (not shown) on the surface opposite to the functional layer, and the adhesive layer or the adhesive layer is the base film 2 and a display element. It is possible to provide an adhesive function at the time of bonding with.

The "peelable functional layer" as used in the present invention means that the base film and the functional layer are in close contact with each other during normal production or general use and cannot be easily peeled off, but only the functional layer is used during polarizing plate processing. A mode in which the functional layer can be peeled off from the base film by external stress when desired.

For example, the stress when the base film is peeled from the functional layer is fixed by sticking the surface of the functional layer on the side opposite to the base film side interface to the glass base material via an acrylic adhesive sheet. Later, using a tensile tester (RTF-1210 manufactured by A & D Co., Ltd.), the base film at one end in the length direction (one side of the width of 25 mm) of the test piece was grasped, and the temperature was 23 ° C. and the humidity was 60%. In a RH atmosphere, at a crosshead speed (grasping movement speed) of 200 mm / min, a 90 ° peeling test (JIS K 6854-1: 1999 "Adhesive-Peeling Adhesive Strength Test Method-Part 1: 90 ° Peeling" When the peeling stress is evaluated by carrying out (according to the above), a state in which the base film and the functional layer can be peeled off with a stress in the range of 0.05 to 2.00 N / 25 mm can be mentioned as an example. If the stress is 0.05 N / 25 mm or more, peeling is less likely to occur during the polarizing plate processing process, and it is preferable. If the stress is 2.00 N / 25 mm or less, the polarizing plate is used when the base film is peeled off. It is preferable because it does not break.

Hereinafter, the configuration of the laminated film of the present invention will be described in detail.

[1] Base film The base film according to the present invention has at least a removable functional layer laminated on it, and the base film has a moisture permeability of 100 to 400 g at a temperature of 40 ° C. and a humidity of 90% RH. / m is in the range of ² · 24h, temperature 23 ° C. of the substrate film, between the humidity 20 ~ 80% RH, the maximum dimensional change in the film plane is in the range of 0.01 to 0.10% It is characterized in that the film thickness of the base film is in the range of 20 to 60 μm.

The laminated film of the present invention can suppress wrinkles and curl deformation even if it is a thin functional film, eliminates the need for a complicated processing process using a protective film or the like without reducing productivity, and is the same as the conventional one. It has the advantage that the polarizing plate can be processed in the polarizing plate processing process.

Among them, the temperature 40 ° C. of the substrate film, the moisture permeability under humidity of 90% RH is, by in the range of ^{100 ~ 400g / m 2 · 24h} , it is possible to impart excellent drying properties at a polarizing plate processing Moreover, it exhibits the effect of suppressing deterioration of the polarizing element layer due to humidity.

Further, when the maximum dimensional change rate in the film surface in the range of the temperature of the base film of 23 ° C. and the humidity of 20 to 80% RH is in the range of 0.01 to 0.10%, the curl of the polarizing plate is obtained. Since it is possible to suppress the warpage of the display device, the effect of preventing the occurrence of display unevenness is exhibited.

Further, when the film thickness of the base film is within the range of 20 to 60 μm, it is possible to provide a thin-film polarizing plate that satisfies the above-mentioned moisture permeability, suppress the polarizing plate curl, and use the polarizer layer as a protective film. It is possible to provide film strength that exhibits the protective effect of. It is preferably in the range of 20 to 40 μm.

The means for adjusting the moisture permeability and the dimensional change rate according to the present invention within the above range is not particularly limited, but the type of resin constituting the base film and the film thickness of the base film are appropriately selected and used. Is preferable.

[1.1] Resin Examples of the resin used for the base film according to the present invention include cycloolefin-based resin, polypropylene-based resin, acrylic-based resin, polyester-based resin, polycarbonate resin, polyarylate-based resin, and styrene-based resin. Examples of the composite resin include cycloolefin-based resins, polyarylate-based resins, styrene-based resins, and composite resins thereof (styrene-(styrene). It is preferable to contain either a meta) acrylate copolymer or a styrene / hydroxystyrene copolymer), and it is more preferable to use a cycloolefin resin.

<Cycloolefin resin>
The cycloolefin-based resin contained in the base film according to the present invention is a polymer of a cycloolefin monomer or a copolymer of a cycloolefin monomer and another copolymerizable monomer. Is preferable.

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

In the general formula (A-1), R ¹ to R ⁴ independently represent 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, ^{all of R 1} to R ⁴ do not represent hydrogen atoms at the same time, R ¹ and R ² do not represent hydrogen atoms at the same time, and R ³ and R ⁴ do not represent hydrogen atoms at the same time. do.

^{The hydrocarbon group having 1 to 30 carbon atoms represented by R 1} to R ⁴ in the general formula (A-1) is preferably, for example, a hydrocarbon group having 1 to 10 carbon atoms, and is preferably a carbon atom. More preferably, it is a hydrocarbon group having a number of 1 to 5. 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 groups, imino groups, ether bonds, silyl ether bonds, thioether bonds and the like. Examples of the hydrocarbon group having 1 to 30 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group and the like.

^{Examples of the polar groups represented by R 1} to R ⁴ in the general formula (A-1) include a carboxy group, a hydroxy group, an alkoxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amide group and a cyano group. Is included. Of these, a carboxy group, a hydroxy group, an alkoxycarbonyl group and an aryloxycarbonyl group are preferable, and an alkoxycarbonyl group and an aryloxycarbonyl group are preferable from the viewpoint of ensuring solubility during solution film formation.

P in the general formula (A-1) is preferably 1 or 2 from the viewpoint of increasing the heat resistance of the optical film. This is because when p is 1 or 2, the obtained polymer becomes bulky and the glass transition temperature tends to be improved.

In the general formula (A-2), R ⁵ represents an alkylsilyl group having a hydrogen atom, a hydrocarbon group having 1 to 5 carbon atoms, or an alkyl group having 1 to 5 carbon atoms. R ⁶ represents a carboxy group, a hydroxy 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 5} in the general formula (A-2) preferably represents a hydrocarbon group having 1 to 5 carbon atoms, and more preferably represents a hydrocarbon group having 1 to 3 carbon atoms.

^{R 6} in the general formula (A-2) preferably represents a carboxy group, a hydroxy group, an alkoxycarbonyl group and an aryloxycarbonyl group, and from the viewpoint of ensuring solubility during solution film formation, the alkoxycarbonyl group and aryl Oxycarbonyl groups are more preferred.

P in the general formula (A-2) preferably represents 1 or 2 from the viewpoint of enhancing the heat resistance of the optical film. This is because when p represents 1 or 2, the obtained polymer becomes bulky and the glass transition temperature tends to improve.

A cycloolefin monomer having a structure represented by the general formula (A-2) is preferable from the viewpoint of improving the solubility in an organic solvent. In general, an organic compound loses its symmetry and thus its crystallinity is lowered, so that its solubility in an organic solvent is improved. ^{Since R 5} and R ⁶ in the general formula (A-2) are substituted with only the ring-constituting carbon atom on one side with respect to the axis of symmetry of the molecule, the symmetry of the molecule is low, that is, the general formula (A-). Since the cycloolefin monomer having the structure represented by 2) has high solubility, it is suitable for producing an optical film by a solution casting method.

The content ratio of the cycloolefin monomer having the structure represented by the general formula (A-2) in the polymer of the cycloolefin monomer is the total of all the cycloolefin monomers constituting the cycloolefin resin. For example, it can be 70 mol% or more, preferably 80 mol% or more, and more preferably 100 mol%. When a cycloolefin monomer having a structure represented by the general formula (A-2) is contained in a certain amount or more, the orientation of the resin is increased, so that the retardation value is likely to increase.

Hereinafter, specific examples of the cycloolefin monomer having the structure represented by the general formula (A-1) are shown in Examples Compounds 1 to 14, and the cycloolefin single having the structure represented by the general formula (A-2) is shown. Specific examples of the merits are shown in Exemplified Compounds 15 to 34.

Examples of copolymerizable monomers that can be copolymerized with cycloolefin monomers include copolymerizable monomers that can be ring-opened and copolymerized with cycloolefin monomers, and addition copolymerization with cycloolefin monomers. Possible copolymerizable monomers and the like are included.

Examples of ring-opening copolymerizable copolymerizable monomers include cycloolefins such as cyclobutene, cyclopentene, cycloheptene, cyclooctene and dicyclopentadiene.

Examples of copolymerizable monomers that can be additionally copolymerized include unsaturated double bond-containing compounds, vinyl-based cyclic hydrocarbon monomers, (meth) acrylates, and the like. Examples of unsaturated double bond-containing compounds include olefin compounds having 2 to 12 (preferably 2 to 8) carbon atoms, and examples thereof include ethylene, propylene and butene. Examples of vinyl-based cyclic hydrocarbon monomers include vinyl cyclopentene-based monomers such as 4-vinylcyclopentene and 2-methyl-4-isopropenylcyclopentene. 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 ratio of the cycloolefin monomer in the copolymer of the cycloolefin monomer and the copolymerizable monomer is, for example, 20 to 80 mol% with respect to the total of all the monomers constituting the copolymer. It can be preferably 30 to 70 mol%.

As described above, the cycloolefin-based resin is obtained by polymerizing a cycloolefin monomer having a norbornene skeleton, preferably a cycloolefin monomer having a structure represented by the general formula (A-1) or (A-2). It is a polymer obtained by copolymerization, and examples thereof include the following.

1) Ring-opening polymer of cycloolefin monomer 2) Ring-opening copolymer of cycloolefin monomer and copolymerizable copolymer with ring-opening copolymer 3) Of 1) or 2) above Hydrogenated ring-opened (co) polymer 4) The ring-opened (co) polymer of 1) or 2) above was cyclized by the Friedercrafts reaction, and then hydrogenated (co) polymer 5) Cycloolefin. Saturated copolymer of monomer and unsaturated double bond-containing compound 6) Addition copolymer of cycloolefin monomer with vinyl-based cyclic hydrocarbon monomer and hydrogen additive thereof 7) Cycloolefin single Alternating copolymers of metric and (meth) acrylate The polymers of 1) to 7) above are all described in known methods, for example, JP-A-2008-107534 and JP-A-2005-227606. It can be obtained by the method of. For example, as the catalyst and solvent used for the ring-opening copolymerization of 2) above, those described in paragraphs 0019 to 0024 of JP-A-2008-107534 can be used, for example. As the catalyst used for hydrogenation of 3) and 6) above, for example, those described in paragraphs 0025 to 0028 of JP-A-2008-107534 can be used. As the acidic compound used in the Friedel-Crafts reaction of 4) above, for example, those described in paragraph 0029 of JP-A-2008-107534 can be used. As the catalyst used for the addition polymerization of 5) to 7) above, for example, those described in paragraphs 0058 to 0063 of JP-A-2005-227606 can be used. The alternating copolymerization reaction of 7) above can be carried out, for example, by the method described in paragraphs 0071 and 0072 of JP-A-2005-227606.

Among them, the polymers of 1) to 3) and 5) above are preferable, and the polymers of 3) and 5) above are more preferable. That is, the cycloolefin-based resin has a structural unit represented by the following general formula (B-1) in that the glass transition temperature of the obtained cycloolefin-based resin can be increased and the light transmittance can be increased. It is preferable that at least one of the structural units represented by the following general formula (B-2) is contained, and only the structural unit represented by the general formula (B-2) is included, or the general formula (B-1) is used. It is more preferable to include both the structural unit represented 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 above-mentioned general formula (A-1), and is represented by the general formula (B-2). The structural unit is a structural unit derived from the cycloolefin monomer represented by the above-mentioned general formula (A-2).

In the general formula (B-1), X represents -CH = CH- or -CH ₂ CH _2- . R ¹ ~ R ⁴ and p are respectively the same as R ¹ ~ R ⁴ and p of the general formula (A-1).

In the general formula (B-2), X represents -CH = CH- or -CH ₂ CH _2- . R ⁵ ~ R ⁶ and p are respectively the same as R ⁵ ~ R ⁶ and p in the general formula (A-2).

The cycloolefin-based resin according to the present invention may be a commercially available product. Examples of commercially available cycloolefin resins include Arton G (eg, G7810, etc.), Arton F, Arton R (eg, R4500, R4900, R5000, etc.) and Arton RX (eg, R4500, R4900, R5000, etc.) manufactured by JSR Corporation. For example, RX4500 etc.) is included.

The intrinsic viscosity [η] inh of the cycloolefin resin ^{is preferably 0.2 to 5 cm 3} / g, more preferably 0.3 to 3 cm ³ / g, as measured at 30 ° C. It is more preferably 4 to 1.5 cm ^{3 / g.}

The number average molecular weight (Mn) of the cycloolefin resin is preferably in the range of 8000 to 100,000, more preferably in the range of 10,000 to 80,000, and further preferably in the range of 12,000 to 50,000. The weight average molecular weight (Mw) of the cycloolefin resin is preferably in the range of 20000 to 300,000, more preferably in the range of 30,000 to 250,000, and even more preferably in the range of 40,000 to 200,000. 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: Methylene chloride Column: Shodex K806, K805, K803G (Three made by Showa Denko KK were connected and used)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0 mL / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation) A calibration curve with 13 samples in the range of Mw = 500 to 2800000 was used. The 13 samples are preferably used at approximately equal intervals.

When the intrinsic viscosity [η] inh, the number average molecular weight and the weight average molecular weight are in the above ranges, the heat resistance, water resistance, chemical resistance, mechanical properties, and molding processability of the base film of the cycloolefin resin are improved. It will be good.

The glass transition temperature (Tg) of the cycloolefin resin is usually 110 ° C. or higher, preferably in the range of 110 to 350 ° C., more preferably in the range of 120 to 250 ° C., and 120 to 220 ° C. It is more preferable that the range is. When Tg is 110 ° C. or higher, deformation under high temperature conditions can be easily suppressed. On the other hand, when Tg is 350 ° C. or lower, the molding process becomes easy, and the deterioration of the resin due to the heat during the molding process is also easily suppressed.

The content of the cycloolefin resin is preferably 70% by mass or more, and more preferably 80% by mass or more with respect to the base film.

<Polyarylate resin>
The polyarylate resin has excellent toughness when used as a base film. The polyialate-based resin contains at least a structural unit derived from an aromatic dialcohol and a structural unit derived from an aromatic dicarboxylic acid.

The aromatic dialcohol is preferably bisphenols represented by the following general formula (I), and more preferably bisphenols represented by the following general formula (II).

In the general formula (I) and the general formula (II), L represents a divalent group. The divalent group is preferably a single bond, an alkylene group, -S-, -SO-, -SO _2- , -O-, -CO- or -CR ₁ _{R 2-} (R ₁ and R ₂ are bonded to each other. To form an aliphatic ring or an aromatic ring).

The alkylene group is preferably an alkylene group having 1 to 10 carbon atoms, and examples thereof include a methylene group, an ethylene group, and an isopropylidene group. The alkylene group may further have a substituent such as a halogen atom or an aryl group.

-CR ₁ R _2- R ₁ and R ₂ are bonded to each other to form an aliphatic ring or an aromatic ring, respectively. The aliphatic ring is preferably an aliphatic hydrocarbon ring having 5 to 20 carbon atoms, and preferably a substituted or unsubstituted cyclohexane ring. The aromatic ring is an aromatic hydrocarbon ring having 6 to 20 carbon atoms, and is preferably a substituted or unsubstituted fluorene ring. _{Examples of -CR 1} R _2- forming a substituted or unsubstituted cyclohexane ring include cyclohexane-1,1-diyl group, 3,3,5-trimethylcyclohexane-1,1-diyl group and the like. Is done. _{Examples of −CR 1} R ₂₋ forming a substituted or unsubstituted fluorene ring include a fluoreneyl group represented by the following formula.

R of the general formula (I) and the general formula (II) can be independently an alkyl group having 1 to 5 carbon atoms or an aryl group having 6 to 10 carbon atoms. n is an integer of 0 to 4, preferably an integer of 0 to 3, independently of each other.

As the aromatic dialcohol component constituting the polyarylate resin, only one type may be used alone, or two or more types may be used in combination.

The aromatic dicarboxylic acid can be terephthalic acid, isophthalic acid or a mixture thereof.

The polyarylate resin may further contain a structural unit derived from an aromatic dicarboxylic acid other than terephthalic acid and isophthalic acid. Examples of such aromatic dicarboxylic acid components are orthophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenic acid, 4,4'-dicarboxydiphenyl ether, bis (p-carboxyphenyl) alkane, 4,4'-. Dicarboxyphenyl sulfone and the like are included.

The polyarylate-based resin according to the present invention may be a commercially available product, and examples thereof include PAR resin "U-100" manufactured by Unitika Ltd. and a weight average molecular weight (Mw): 100,000.

<Styrene / (meth) acrylate copolymer>
The styrene / (meth) acrylate copolymer (hereinafter, also referred to as “styrene / acrylic resin”) has excellent transparency when used as a base film.

The styrene / acrylic resin is formed by addition polymerization of at least a styrene monomer and a (meth) acrylic acid ester monomer. Styrene monomer includes, in addition to styrene represented by the structural formula _{_{CH 2 = CH-C 6 H}} 5, comprising a styrene derivative having a known side-chain or functional groups styrene structure.

The (meth) acrylic acid ester monomer is CH (R ₁ ) = CHCOOR ₂ (R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents an alkyl group having 1 to 24 carbon atoms). In addition to the represented acrylic acid ester and methacrylic acid ester, an acrylic acid ester derivative and a methacrylic acid ester derivative having known side chains and functional groups in the structure of these esters are included.

Examples of styrene monomers include styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene, p-phenylstyrene, p-ethylstyrene, 2,4-dimethylstyrene, p-. Includes tert-butyl styrene, pn-hexyl styrene, pn-octyl styrene, pn-nonyl styrene, pn-decyl styrene and pn-dodecyl styrene.

Examples of (meth) acrylic acid ester monomers include methyl acrylate, ethyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-octyl acrylate, 2-ethylhexyl acrylate (2EHA), and stearyl. Acrylate monomers such as acrylates, lauryl acrylates and phenyl acrylates; methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, n-octyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate. , Methacrylate esters such as lauryl methacrylate, phenyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoethyl methacrylate;

In the present specification, "(meth) acrylic acid ester monomer" is a general term for "acrylic acid ester monomer" and "methacrylic acid ester monomer", and one or both of them may be used. means. For example, "methyl (meth) acrylate" means one or both of "methyl acrylate" and "methyl methacrylate".

The above (meth) acrylic acid ester monomer may be one kind or more. For example, forming a copolymer using a styrene monomer and two or more kinds of acrylic acid ester monomers, or using a styrene monomer and two or more kinds of methacrylic acid ester monomers to have a common weight. It is possible to form a coalescence and to form a copolymer by using a styrene monomer, an acrylic acid ester monomer and a methacrylic acid ester monomer in combination.

From the viewpoint of controlling the plasticity of the styrene / acrylic resin, the content of the structural unit derived from the styrene monomer in the styrene / acrylic resin is preferably in the range of 40 to 90% by mass. Further, the content of the structural unit derived from the (meth) acrylic acid ester monomer in the amorphous resin is preferably in the range of 10 to 60% by mass.

The styrene / acrylic resin may further contain a structural unit derived from a monomer other than the styrene monomer and the (meth) acrylic acid ester monomer. The other monomer is preferably a compound having a carboxy group or a hydroxy group.

The other monomer is preferably a compound that ester-bonds with a hydroxy group (-OH) derived from a polyhydric alcohol or a carboxy group (-COOH) derived from a polyvalent carboxylic acid. That is, it is a polymer that can be additive-polymerized with respect to the styrene monomer and the (meth) acrylic acid ester monomer, and is further polymerized by a compound having a carboxy group or a hydroxy group (amphoteric compound). Is preferable.

Examples of the above compounds include compounds having a carboxy group such as acrylic acid, methacrylic acid, maleic acid, itaconic acid, silicic acid, fumaric acid, maleic acid monoalkyl ester, and itaconic acid monoalkyl ester; 2-hydroxyethyl. (Meta) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, Compounds having a hydroxy group such as polyethylene glycol mono (meth) acrylate; are included.

The styrene / acrylic resin can be synthesized by a method of polymerizing a monomer using a known oil-soluble or water-soluble polymerization initiator. Examples of oil-soluble polymerization initiators include azo-based or diazo-based polymerization initiators and peroxide-based polymerization initiators.

Examples of the azo-based or diazo-based polymerization initiator include 2,2'-azobis- (2,4-dimethylvaleronitrile), 2,2'-azobisisobutyronitrile, and 1,1'-azobis (2,4-dimethylvaleronitrile). Cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile and azobisisobutyronitrile are included.

Examples of peroxide-based polymerization initiators include benzoyl peroxide, methyl ethyl ketone peroxide, diisopropylperoxycarbonate, cumenehydroperoxide, t-butylhydroperoxide, di-t-butyl peroxide, dicumyl peroxide, 2 , 4-Dichlorobenzoyl peroxide, lauroyl peroxide, 2,2-bis- (4,5-t-butylperoxycyclohexyl) propane and tris- (t-butylperoxy) triazine.

Further, when synthesizing a styrene / acrylic resin by an emulsion polymerization method, a water-soluble radical polymerization initiator can be used as a polymerization initiator. Examples of the water-soluble polymerization initiator include persulfates such as potassium persulfate and ammonium persulfate, azobisaminodipropane acetate, azobiscyanovaleric acid and its salts, and hydrogen peroxide.

The weight average molecular weight (Mw) of the styrene / acrylic resin is preferably in the range of 10,000 to 500,000, more preferably in the range of 50,000 to 200,000, from the viewpoint of easy control of plasticity.

The styrene / acrylic resin according to the present invention may be a commercially available product, and MS resin "TX320XL" manufactured by Denka Corporation can be mentioned as an example.

<Styrene / hydroxystyrene copolymer>
The styrene / hydroxystyrene copolymer (hereinafter, also referred to as “styrene / hydroxystyrene resin”) is excellent in heat resistance and chemical resistance when used as a base film.

Examples of styrene-based monomers include styrene; alkyl-substituted styrenes such as α-methylstyrene, β-methylstyrene and p-methylstyrene; and halogen-substituted styrenes such as 4-chlorostyrene and 4-bromostyrene. can.

Examples of the hydroxystyrene monomer include hydroxystyrenes such as 4-hydroxystyrene, p-hydroxystyrene, α-methyl-p-hydroxystyrene, 2-methyl-4-hydroxystyrene, and 3,4-dihydroxystyrene. can.

The weight average molecular weight (Mw) of the styrene / hydroxystyrene resin is preferably in the range of 10,000 to 500,000, more preferably in the range of 50,000 to 200,000, from the viewpoint of easy control of plasticity.

The styrene / hydroxystyrene resin according to the present invention may be a commercially available product, and examples thereof include a styrene / hydroxystyrene copolymer "Marcalinker CST50" manufactured by Maruzen Petrochemical Co., Ltd. and a weight average molecular weight (Mw): 60000. be able to.

[1.2] Additives <Plasticizer>
The base film may contain a plasticizer. The plasticizer is not particularly limited, but is preferably a polyhydric alcohol ester plasticizer, a phthalic acid ester plasticizer, a citric acid plasticizer, a fatty acid ester plasticizer, a phosphoric acid ester plasticizer, or a polyvalent carboxylic acid. It is preferably selected from an ester-based plasticizer, a polyester-based plasticizer, and the like, and a polyester-based plasticizer is more preferable.

The polyhydric alcohol ester-based plasticizer is a plasticizer composed of an ester of a divalent or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule. It is preferably a 2- to 20-valent aliphatic polyhydric alcohol ester.

Examples of the phthalate-based plasticizer include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate and dicyclohexyl terephthalate.

Examples of the citrate ester-based plasticizer include acetyltrimethyl citrate, acetyltriethyl citrate, and acetyltributyl citrate.

Examples of fatty acid ester-based plasticizers include butyl oleate, methylacetyl ricinoleate, and dibutyl sebacate.

Examples of the phosphoric acid ester-based plasticizer include triphenyl phosphate, tricresyl phosphate, cresil diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, and tributyl phosphate.

The polyvalent carboxylic acid ester-based plasticizer is composed of an ester of a polyvalent carboxylic acid having a divalent value or higher, preferably a divalent to 20-valent carboxylic acid, and an alcohol. The aliphatic polyvalent carboxylic acid is preferably 2 to 20 valent, and the aromatic polyvalent carboxylic acid and the alicyclic polyvalent carboxylic acid are preferably 3 to 20 valent.

The polyvalent carboxylic acid is represented by the following general formula (a).

General formula (a) Rb (COOH) _m (OH) _n
In the general formula (a), Rb is an organic group having a (m + n) valence, m is a positive integer of 2 or more, n is an integer of 0 or more, a COOH group is a carboxy group, and an OH group is an alcoholic hydroxy group or a phenolic hydroxy group. Represents a group.

The polyester-based plasticizer is not particularly limited, but a polyester-based plasticizer having an aromatic ring or a cycloalkyl ring in the molecule can be used. The polyester-based plasticizer is not particularly limited, but for example, an aromatic terminal ester-based plasticizer represented by the following general formula (b) can be used.

General formula (b) B- (GA _{) n-GB}
In the general formula (b), B is a benzenemonocarboxylic acid residue, G is an alkylene glycol residue having 2 to 12 carbon atoms, an aryl glycol residue having 6 to 12 carbon atoms, or an oxyalkylene glycol having 4 to 12 carbon atoms. The residue, A, represents an alkylenedicarboxylic acid residue having 4 to 12 carbon atoms or an aryldicarboxylic acid residue having 6 to 12 carbon atoms, and n represents an integer of 1 or more.

In the general formula (b), the benzenemonocarboxylic acid residue represented by B, the alkylene glycol residue or oxyalkylene glycol residue or arylglycol residue represented by G, the alkylenedicarboxylic acid residue or aryldicarboxylic acid represented by A. It is composed of an acid residue and is obtained by the same reaction as a normal polyester-based plasticizer.

Examples of the benzene monocarboxylic acid component of the polyester-based plasticizer used in the present invention include benzoic acid, parataciaributyl benzoic acid, orthotoluic acid, metatoluic acid, paratoluic acid, dimethyl benzoic acid, ethyl benzoic acid, and normal propyl benzoic acid. There are acids, aminobenzoic acid, acetoxybenzoic acid and the like, and these can be used as one kind or a mixture of two or more kinds, respectively.

Examples of the alkylene glycol component having 2 to 12 carbon atoms of the polyester-based plasticizer used in the present invention include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, and 1,3-. Butanediol, 1,2-propanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl) Glycol), 2,2-diethyl-1,3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3propanediol (3,3-dimethylolheptan), 3-Methyl-1,5-pentanediol 1,6-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2-methyl-1,8 There are -octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecanediol and the like, and these glycols are used as one kind or a mixture of two or more kinds. In particular, alkylene glycol having 2 to 12 carbon atoms is particularly preferable because it has excellent compatibility with cellulose ester.

Further, examples of the oxyalkylene glycol component having 4 to 12 carbon atoms of the aromatic terminal ester include diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol and the like, and these glycols have 1 It can be used as a seed or a mixture of two or more.

Examples of the alkylenedicarboxylic acid component having 4 to 12 carbon atoms of the aromatic terminal ester include succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, azelaic acid, sebacic acid, dodecanediocarboxylic acid and the like. , Each used as one or a mixture of two or more. Examples of the allylenedicarboxylic acid component having 6 to 12 carbon atoms include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, and 1,4-naphthalenedicarboxylic acid.

The polyester-based plasticizer used in the present invention preferably has a number average molecular weight in the range of preferably in the range of 300 to 1500, more preferably in the range of 400 to 1000. The acid value is 0.5 mgKOH / g or less, the hydroxy value (hydroxyl value) is 25 mgKOH / g or less, more preferably the acid value is 0.3 mgKOH / g or less, and the hydroxy value (hydroxyl value) is 15 mgKOH / g or less. It is a thing.

The number average molecular weight and weight average molecular weight of the polyester used in the present invention can be measured by gel permeation chromatography. The measurement conditions are as described above.

<UV absorber>
The base film according to the present invention may also contain an ultraviolet absorber. Examples of the ultraviolet absorber used include benzotriazole-based, 2-hydroxybenzophenone-based, and salicylic acid phenyl ester-based agents. For example, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (3, Triazoles such as 5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone And other benzophenones can be exemplified.

Here, among the ultraviolet absorbers, the ultraviolet absorber having a molecular weight of 400 or more is hard to volatilize at a high boiling point and is hard to scatter even during high-temperature molding, so that the weather resistance is effectively improved by adding a relatively small amount. be able to.

Examples of ultraviolet absorbers having a molecular weight of 400 or more include 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole and 2,2-methylenebis [4- (1,1). 1,3,3-Tetrabutyl) -6- (2H-benzotriazole-2-yl) phenol] and other benzotriazoles, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis ( Hindered amines such as 1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, as well as 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonic acid. Bis (1,2,2,6,6-pentamethyl-4-piperidyl), 1- [2- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4 -[3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidin and other molecules have both hindered phenol and hindered amine structures. Examples thereof include hybrid systems, which can be used alone or in combination of two or more. Among these, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole and 2,2-methylenebis [4- (1,1,3,3-) Tetrabutyl) -6- (2H-benzotriazole-2-yl) phenol] is particularly preferred.

<Antioxidant>
The base film according to the present invention may contain an antioxidant. Antioxidants are also called anti-deterioration agents.

The antioxidant has a role of delaying or preventing the decomposition of the base film due to, for example, the amount of halogen remaining in the base film or the phosphoric acid of the phosphoric acid-based plasticizer, and thus the base film. It is preferable to contain it in.

As such an antioxidant, a hindered phenol-based compound is preferably used, for example, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrax [3- (3,5-di). -T-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,6-hexanediol-bis [3 -(3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino)- 1,3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t) -Butyl-4-hydroxyphenyl) propionate, N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 1,3,5-trimethyl-2,4 , 6-Tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, Tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate and the like. ..

In particular, 2,6-di-t-butyl-p-cresol, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], triethylene glycol-bis [3 -(3-T-Butyl-5-methyl-4-hydroxyphenyl) propionate] is preferable. Further, for example, a hydrazine-based metal inactivating agent such as N, N'-bis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyl] hydrazine or tris (2,4-di-). A phosphorus-based processing stabilizer such as t-butylphenyl) phosphite may be used in combination.

The amount of these compounds added is preferably in the range of 1% by mass to 1.0% by mass, more preferably in the range of 10 to 1000% by mass with respect to 100% by mass of the base resin.

<Fine particles>
The base film according to the present invention preferably contains fine particles.

Examples of the fine particles used in the present invention include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, and hydrated silicic acid. Calcium, aluminum silicate, magnesium silicate and calcium phosphate can be mentioned. Further, fine particles of an organic compound can also be preferably used. Examples of organic compounds include polytetrafluoroethylene, cellulose acetate, polystyrene, polymethylmethacrylate, polyppill methacrylate, polymethylacrylate, polyethylene carbonate, acrylic styrene resin, silicone resin, polycarbonate resin, benzoguanamine resin, and melamine resin. , Polyolefin-based powder, polyester-based resin, polyamide-based resin, polyimide-based resin, or polyfluorinated ethylene-based resin, crushed grades of organic polymer compounds such as starch are also mentioned. Alternatively, a polymer compound synthesized by a suspension polymerization method, a polymer compound made spherical by a spray-drying method, a dispersion method, or the like, or an inorganic compound can be used.

Fine particles containing silicon are preferable in that the turbidity is low, and silicon dioxide is particularly preferable.

The average particle size of the primary particles of the fine particles is preferably in the range of 5 to 400 nm, and more preferably in the range of 10 to 300 nm.

These may be mainly contained as secondary aggregates having a particle size in the range of 0.05 to 0.3 μm, and particles having an average particle size in the range of 100 to 400 nm are contained as primary particles without agglomeration. It is also preferable that the particles are used.

The content of these fine particles is preferably in the range of 0.01 to 1% by mass, particularly preferably in the range of 0.05 to 0.5% by mass, based on 100% by mass of the total mass of the base film. In the case of a multi-layered base material (optical film) by the cocurrent spreading method, it is preferable that the surface layer (skin layer) contains fine particles in this amount.

The fine particles of silicon dioxide are commercially available under the trade names of Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, and TT600 (all manufactured by Nippon Aerosil Co., Ltd.) and can be used. can.

The fine particles of zirconium oxide are commercially available under the trade names of Aerosil R976 and R811 (all manufactured by Nippon Aerosil Co., Ltd.) and can be used.

Examples of polymers include silicone resin, fluororesin and acrylic resin. Silicone resins are preferable, and those having a three-dimensional network structure are preferable. For example, products of Tospearl 103, 105, 108, 120, 145, 3120 and 240 (all manufactured by Toshiba Silicone Co., Ltd.). It is commercially available under the name and can be used.

Among these, Aerosil 200V and Aerosil R972V are particularly preferably used because they have a large effect of lowering the coefficient of friction while keeping the turbidity of the base film low. In the base film according to the present invention, the coefficient of dynamic friction of at least one surface is preferably in the range of 0.2 to 1.0.

When the base film is formed by casting a cycloolefin resin-containing solution to form a film, various additives may be added in batch to the dope which is the cycloolefin resin-containing solution before film formation, or the additives may be dissolved. A liquid may be prepared separately and added in-line. In particular, it is preferable to add a part or all of the fine particles in-line in order to reduce the load on the filter medium.

When the additive solution is added in-line, it is preferable to dissolve a small amount of cycloolefin resin in order to improve the miscibility with the doping. The amount of the cycloolefin-based resin is preferably in the range of 1 to 10 parts by mass, and more preferably in the range of 3 to 5 parts by mass with respect to 100 parts by mass of the solvent.

In order to perform in-line addition and mixing in the present invention, for example, an in-line mixer such as a static mixer (manufactured by Toray Engineering) or SWJ (Toray static in-tube mixer Hi-Mixer) is preferably used.

[1.3] Method for Producing Base Film The method for producing the base film of the present invention includes a normal inflation method, a T-die method, a calendar method, a cutting method, a casting method, an emulsion method, a hot press method, and the like. However, from the viewpoints of suppressing coloration, suppressing foreign matter defects, suppressing optical defects such as die lines, etc., the solution casting method and the melt casting method are preferable, and the solution casting method is particularly used. It is more preferable that the temperature in the processing step is low, and therefore, from the viewpoint of imparting high functionality by using various additives. Hereinafter, the “solution casting method” preferable to the present invention will be described.

<Solution casting method>
When the film is formed by the solution casting method, the method for producing the base film according to the present invention is a step of dissolving and dispersing an additive such as a thermoplastic resin and the above-mentioned fine particles in a solvent to prepare a dope (dissolving step; Dope preparation step), casting the dope onto an endless metal support (casting step), drying the cast dope as a web (solvent evaporation step), peeling from the metal support. It is preferable to include a step (peeling step), drying, stretching, a step of holding the width (stretching / width holding / drying step), and a step of winding the finished film into a roll (winding step).

FIG. 2 is a diagram schematically showing an example of a dope preparation step, a casting step, and a drying step (solvent evaporation step) of the solution casting method.

A large agglomerate is removed from the charging pot A41 with the filter A44, and the liquid is sent to the stock pot A42. Then, various additive liquids are added from the stock kettle A42 to the main dope melting kettle A1.

After that, the main dope is filtered by the main filter A3, and the additive additive liquid is added in-line from A16.

In many cases, the main dope may contain about 10 to 50% by mass of the return material.

The return material is a finely crushed film, and the material that is generated when the film is formed by cutting off both sides of the film, or the original film that is out of specification due to scratches, etc. is used.

Further, as the raw material of the resin used for the dope preparation, those obtained by pelletizing a cycloolefin resin, an acrylic resin, or other additives as a base resin in advance can also be preferably used.

Each process will be described below.

1) Dissolution step (dope preparation step)
Hereinafter, as one embodiment of the present invention, the dissolution step will be described by taking the case where a cycloolefin resin (hereinafter, also referred to as “COP”) is used as the thermoplastic resin as an example, but the present invention is not limited thereto.

This step is a step of dissolving the COP, in some cases, other compounds in a dissolution kettle in a solvent mainly containing a good solvent for the COP while stirring to form a dope, or in the COP solution, in some cases, other This is a step of mixing compound solutions to form a dope which is a main solution.

It is preferable that the COP concentration in the dope is high because the drying load after casting on the metal support can be reduced, but if the COP concentration is too high, the load during filtration increases and the filtration accuracy deteriorates. The concentration at which these are compatible is preferably in the range of 10 to 35% by mass, more preferably in the range of 15 to 30% by mass.

The solvent used for doping may be used alone or in combination of two or more, but it is preferable to use a mixture of a good solvent and a poor solvent of COP in terms of production efficiency, and the one having more good solvents. Is preferable in terms of the solubility of COP.

The preferable range of the mixing ratio of the good solvent and the poor solvent is the range of 70 to 98% by mass of the good solvent and the range of 2 to 30% by mass of the poor solvent. The good solvent and the poor solvent are defined as a good solvent in which the COP to be used is dissolved alone, and a poor solvent in which the COP used alone is swollen or not dissolved. Therefore, the good solvent and the poor solvent change depending on the average degree of substitution of 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, and methyl acetoacetate. Particularly preferred are methylene chloride or methyl acetate.

The poor solvent used in the present invention is not particularly limited, but for example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone and the like are preferably used. Further, it is preferable that the dope contains water in the range of 0.01 to 2% by mass.

Further, as the solvent used for dissolving the COP, the solvent removed from the film by drying in the film forming process is recovered and reused.

The recovery solvent may contain a small amount of additives added to the COP, such as a plasticizer, an ultraviolet absorber, a polymer, and a monomer component, but even if these are contained, they are preferably reused. It can be purified and reused if necessary.

A general method can be used as the COP dissolution method when preparing the above-mentioned dope. Specifically, a method performed at normal pressure, a method performed below the boiling point of the main solvent, and a method performed by pressurizing above the boiling point of the main solvent are preferable, and when heating and pressurization are combined, heating can be performed above the boiling point at normal pressure.

Further, a method of stirring and dissolving while heating at a temperature above the boiling point of the solvent at normal pressure and under pressure so that the solvent does not boil is also preferable in order to prevent the generation of massive undissolved substances called gels and mamaco.

Further, a method in which COP is mixed with a poor solvent to moisten or swell, and then a good solvent is further added to dissolve the COP is also preferably used.

Pressurization may be performed by a method of press-fitting an inert gas such as nitrogen gas or a method of increasing the vapor pressure of the solvent by heating. The heating is preferably performed from the outside, and for example, the jacket type is preferable because the temperature can be easily controlled.

A higher heating temperature with the addition of a solvent is preferable from the viewpoint of COP solubility, but if the heating temperature is too high, the required pressure increases and productivity deteriorates.

The preferred heating temperature is in the range of 45 to 120 ° C, more preferably in the range of 60 to 110 ° C, and even more preferably in the range of 70 ° C to 105 ° C. In addition, the pressure is adjusted so that the solvent does not boil at the set temperature.

Alternatively, a cooling dissolution method is also preferably used, which allows the COP to be dissolved in a solvent such as methyl acetate.

Next, it is preferable to filter this COP solution (dope during or after dissolution) 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 matter and the like, but if the absolute filtration accuracy is too small, there is a problem that clogging of the filter material is likely to occur. Therefore, a filter medium having an absolute filtration accuracy of 0.008 mm or less is preferable, a filter medium in the range of 0.001 to 0.008 mm is more preferable, and a filter medium in the range of 0.003 to 0.006 mm is further preferable.

The material of the filter medium is not particularly limited, and a normal filter medium can be used, but a plastic filter medium such as polypropylene or Teflon (registered trademark) or a metal filter medium such as stainless steel does not cause fibers to fall off. preferable.

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

A bright spot foreign substance is the opposite when two polarizing plates are arranged in a cross-nicoled state, a film or the like is placed between them, light is applied from the side of one polarizing plate, and observation is performed from the side of the other polarizing plate. It is a point (foreign matter) in which light from the side appears to leak, and it is preferable that the ^{number of bright spots having a diameter of 0.01 mm or more is 200 / cm 2 or less.} It is more preferably 100 pieces / cm ² or less, further preferably 50 pieces / m ² or less, and further preferably 0 to 10 pieces / cm ² or less. Further, it is preferable that there are few bright spots of 0.01 mm or less.

Dope filtration can be performed by a usual method, but the method of filtering while heating at a temperature above the boiling point of the solvent at normal pressure and within the range where the solvent does not boil under pressure is the method of filtering the filtration pressure before and after filtration. The increase in the difference (referred to as "differential pressure") is small, which is preferable.

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

It is preferable that the filter pressure is small. The filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, and even more preferably 1.0 MPa or less.

2) Casting step Subsequently, the dope is cast on the metal support. That is, in this step, the dope is sent to the pressure die A30 through a liquid feed pump (for example, a pressure type metering gear pump) and transferred indefinitely, such as an endless metal belt A31, for example, a stainless band, a rotating metal drum, or the like. This is a step of casting the dope from the pressure die slit at the casting position on the metal support of the above.

A pressure die that can adjust the slit shape of the die base and makes it easy to make the film thickness uniform is preferable. The pressure die includes a coat hanger die, a T die, and the like, and any of them is preferably used. The surface of the metal support is preferably a mirror surface. In order to increase the film forming speed, two or more pressure dies may be provided on the metal support, and the doping amount may be divided and layered. Alternatively, it is also preferable to obtain a film roll having a laminated structure by a co-flow spreading method in which a plurality of dope is cast at the same time.

The cast width is preferably 1.3 m or more from the viewpoint of productivity. More preferably, it is in the range of 1.3 to 4.0 m. If it exceeds 4.0 m, there is a risk that stripes will appear in the manufacturing process and the stability in the subsequent transport process will decrease. More preferably, it is in the range of 1.3 to 3.0 m in terms of transportability and productivity.

The metal support in the casting process is preferably a mirror-finished surface, and the metal support is preferably a stainless steel belt or a drum whose surface is plated with a casting.

The surface temperature of the metal support in the casting process is in the range of -50 ° C to less than the boiling point of the solvent, and a higher temperature is preferable because the drying speed of the web can be increased, but if it is too high, the web may foam. , Flatness may deteriorate.

The preferred support temperature is in the range of 0 to 55 ° C, more preferably in the range of 22 to 50 ° C. Alternatively, it is also a preferable method to gel the web by cooling and peel it off from the drum in a state containing a large amount of residual solvent.

The method of controlling the temperature of the metal support is not particularly limited, but there are a method of blowing hot air or cold air and a method of bringing hot water into contact with the back side of the metal support. It is preferable to use hot water because the heat transfer is more efficient and the time until the temperature of the metal support becomes constant is short. When using warm air, air with a temperature higher than the target temperature may be used.

3) Solvent evaporation step This step is a step of heating a web (a dope film formed by casting a dope on a casting support and calling the web) on the casting support to evaporate the solvent. Is.

To evaporate the solvent, there are a method of blowing wind from the web side and / or a method of transferring heat from the back surface of the support with a liquid, a method of transferring heat from the front and back surfaces by radiant heat, etc. The drying efficiency is good and preferable. In addition, a method of combining them is also preferably used. It is preferable that the web on the support after casting is dried on the support in an atmosphere in the range of 35 to 100 ° C. In order to maintain the atmosphere in the range of 35 to 100 ° C., it is preferable to blow warm air at this temperature on the upper surface of the web or heat it by means such as infrared rays.

From the viewpoint of surface quality, moisture permeability, and peelability, it is preferable to peel the web from the support within 30 to 120 seconds.

4) Peeling step Next, the web is peeled from the metal support. That is, this step is a step of peeling the web in which the solvent has evaporated on the metal support at the peeling position. The peeled web is sent to the next process.

The temperature at the peeling position on the metal support is preferably in the range of -50 to 40 ° C, more preferably in the range of 10 to 40 ° C, and most preferably in the range of 15 to 30 ° C.

The amount of residual solvent at the time of peeling the web on the metal support at the time of peeling is appropriately adjusted depending on the strength of the drying conditions, the length of the metal support, and the like. In order for the film to exhibit good flatness, the amount of residual solvent when the web is peeled from the metal support is preferably in the range of 10 to 150% by mass. When peeling at a time when the amount of residual solvent is larger, if the web is too soft, the flatness at the time of peeling is impaired, and slippage and vertical streaks are likely to occur due to the peeling tension. The amount is decided. It is more preferably in the range of 20 to 40% by mass or 60 to 130% by mass, and particularly preferably in the range of 20 to 30% by mass or 70 to 120% by mass.

In the present invention, the amount of residual solvent is defined by the following formula.

Residual solvent amount (mass%) = [(MN) / N] × 100
In addition, M is the mass of the sample collected at any time during or after the production of the web or film, and N is the mass after heating M at 115 ° C. for 1 hour.

The peeling tension when peeling the metal support and the film is preferably 300 N / m or less. More preferably, it is in the range of 196 to 245 N / m, but when wrinkles are likely to occur during peeling, it is preferable to peel with a tension of 190 N / m or less. The peeling tension is preferably 300 N / m or less.

5) Drying / stretching / width holding process (drying)
In the film drying step, the web is preferably peeled from the metal support and further dried to reduce the residual solvent amount to 1% by mass or less, more preferably 0.1% by mass or less, and particularly preferably 0. It is ~ 0.01% by mass or less.

In the film drying process, a roll drying method (a method in which the web is alternately passed through a large number of rollers arranged above and below to dry) or a tenter method is adopted while transporting the web. For example, after peeling, the web is transferred by using a drying device 35 that alternately passes and conveys the web through a plurality of rollers arranged in the drying device, and / or a tenter stretching device 34 that clips and conveys both ends of the web with clips. dry.

The means for drying the web is not particularly limited, and generally it can be performed by hot air, infrared rays, heating rollers, microwaves, etc., but it is preferable to use hot air from the viewpoint of simplicity. Too rapid drying tends to impair the flatness of the finished film. Drying at high temperature should be performed when the residual solvent is about 8% by mass or less. Throughout, drying is generally carried out in the range of 30-250 ° C. In particular, it is preferable to dry in the range of 35 to 200 ° C. It is preferable that the drying temperature is gradually increased.

When using a tenter stretching device, it is preferable to use a device that can independently control the film gripping length (distance from the start of gripping to the end of gripping) by the left and right gripping means of the tenter. Further, in the tenter step, it is also preferable to intentionally create sections having different temperatures in order to improve the flatness.

It is also preferable to provide a neutral zone so that the respective compartments do not interfere with each other between different temperature compartments.

(Stretching / maintaining width)
Subsequently, it is preferable to stretch the web exfoliated from the metal support in at least one direction. The orientation of the molecules in the film can be controlled by the stretching treatment. In order to obtain the desired retardation values Ro and Rt in the present invention, it is preferable that the film has the structure of the present invention, and the refractive index is controlled by controlling the transport tension and stretching operation. For example, the retardation value can be varied by lowering or increasing the tension in the longitudinal direction.

As a specific stretching method, two axes are sequentially or simultaneously with respect to the longitudinal direction of the web (film forming direction; spreading direction; MD direction) and the direction orthogonal to the web surface, that is, the width direction (TD direction). It can be stretched or uniaxially stretched. Preferably, it is a biaxially stretched film in which biaxial stretching is performed in the casting direction (MD direction) and the width direction (TD direction), but the film according to the present invention may be a uniaxially stretched film. It may be an unstretched film. The stretching operation may be performed in multiple stages. Further, when biaxial stretching is performed, simultaneous biaxial stretching may be performed, or biaxial stretching may be performed step by step. In this case, the term “stepwise” means, for example, that stretching in different stretching directions can be sequentially performed, stretching in the same direction is divided into multiple stages, and stretching in different directions is added to any of the steps. Is also possible.

For example, the following stretching steps are also possible:
・ Stretching in the casting direction → Stretching in the width direction → Stretching in the casting direction → Stretching in the casting direction ・ Stretching in the width direction → Stretching in the width direction → Stretching in the casting direction → Stretching in the casting direction Simultaneous biaxial stretching includes the case of stretching in one direction and contracting the other by relaxing the tension.

The stretching ratios in the biaxial directions orthogonal to each other are preferably in the range of 0.8 to 1.5 times in the casting direction and 1.1 to 2.5 times in the width direction, respectively. , It is preferable to carry out in the range of 0.8 to 1.2 times in the flow direction and 1.2 to 2.0 times in the width direction.

The stretching temperature is usually preferably a temperature in the range of Tg to Tg + 60 ° C. of the resin constituting the film. Usually, the stretching temperature is preferably in the range of 120 to 200 ° C, more preferably in the range of 120 to 180 ° C.

The residual solvent in the web at the time of stretching is preferably in the range of 20 to 0% by mass, more preferably in the range of 15 to 0% by mass.

There is no particular limitation on the method of stretching the web. For example, a method of making a difference in peripheral speed between multiple rollers and stretching in the vertical direction using the difference in peripheral speed between the rollers, fixing both ends of the web with clips or pins, and widening the distance between the clips and pins in the direction of travel. A method of stretching in the vertical direction, a method of similarly spreading in the horizontal direction and stretching in the horizontal direction, a method of spreading in the vertical and horizontal directions at the same time and stretching in both the vertical and horizontal directions, and the like can be mentioned. Of course, these methods may be used in combination. Above all, it is particularly preferable to stretch in the width direction (lateral direction) by a tenter method in which both ends of the web are gripped by clips or the like.

Further, in the case of the so-called tenter method, it is preferable to drive the clip portion by the linear drive method because smooth stretching can be performed and the risk of breakage can be reduced.

It is preferable that these width maintenance or lateral stretching in the film forming process is performed by a tenter, and either a pin tenter or a clip tenter may be used.

Assuming that the slow axis or the phase advance axis of the base film according to the present invention exists in the film surface and the angle formed by the film forming direction is θ1, θ1 is preferably -1 ° or more and + 1 ° or less. More preferably, it is 0.5 ° or more and + 0.5 ° or less.

This θ1 can be defined as an orientation angle, and the measurement of θ1 can be performed using an automatic birefringence meter KOBRA-21ADH (manufactured by Oji Measuring Instruments Co., Ltd.). Satisfying each of the above relationships with θ1 can contribute to obtaining high brightness in the displayed image, suppressing or preventing light leakage, and can contribute to obtaining faithful color reproduction in the color liquid crystal display device.

6) Winding step Finally, a film roll is obtained by winding the obtained web (finished film). More specifically, it is a step of winding the film as a film by the winder A37 after the amount of residual solvent in the web becomes 2% by mass or less, and dimensional stability is achieved by reducing the amount of residual solvent to 0.4% by mass or less. A film having good properties can be obtained. In particular, it is preferable to wind up in the range of 0.00 to 0.10% by mass.

As the winding method, a commonly used one may be used, and there are a constant torque method, a constant tension method, a taper tension method, a program tension control method with a constant internal stress, etc., and these can be used properly.

Before winding, the end is slit to the width of the product and cut off, and knurling is applied to both ends of the film to prevent sticking and scratches during winding.

Note that the gripping part of the clip at both ends of the film is usually cut because the film is deformed and cannot be used as a product. If the material has not deteriorated due to heat, it will be reused after recovery.

The base film according to the present invention is preferably a long film, specifically, a film having a length of about 100 to 10000 m, and is usually provided in a roll form.

[2] Functional Layer The functional layer according to the present invention is preferably bonded to a polarizing element layer to form a polarizing plate, and can function as an optical film such as a polarizing plate protective film or a retardation film. At that time, the base film according to the present invention may be peeled off from the functional layer or may be left as it is.

The layer thickness of the functional layer according to the present invention is in the range of 1 to 19 μm and in the range of 2 to 10 μm to provide a thin polarizing plate, and at the same time, wrinkle or curl deformation of the functional layer which is a thin film. It is preferable from the viewpoint of suppressing the above. If it is less than 1 μm, the strength as a functional layer cannot be maintained, wrinkles and curl deformation are likely to occur, and the protective function of the polarizer layer is insufficient. If it exceeds 19 μm, optical unevenness may be caused in a display device provided with a polarizing plate using the functional layer, and it becomes difficult to form a thin polarizing plate.

[2.1] Resin The resin used for the functional layer according to the present invention is not particularly limited, and is a (meth) acrylic resin, a cycloolefin resin, a cellulose acylate resin, a fumaric acid diester resin, or a polyimide resin. It can be resin or the like. As the cycloolefin-based resin, the same cycloolefin-based resin as the cycloolefin-based resin described in the base film can be appropriately used.

<(Meta) acrylic resin>
The (meth) acrylic resin used for the functional layer preferably contains at least a structural unit (U1) derived from methyl methacrylate and a structural unit (U2) derived from phenylmaleimide. The (meth) acrylic resin containing the structural unit (U2) derived from phenylmaleimide can reduce the coefficient of thermal expansion (CTE) of the functional layer.

The (meth) acrylic resin may further contain other structural units other than the above. Examples of such other structural units include (meth) acrylic acid alkyl esters such as adamantyl acrylate; (meth) acrylic acid cycloalkyl esters such as 2-ethylhexyl acrylate. Above all, it is preferable to further contain the structural unit (U3) derived from the acrylic acid alkyl ester from the viewpoint of reducing the deterioration of brittleness due to the inclusion of the structural unit (U2) derived from phenylmaleimide.

That is, the (meth) acrylic resin contains a structural unit (U1) derived from methyl methacrylate, a structural unit (U2) derived from phenylmaleimide, and a structural unit (U3) derived from an acrylic acid alkyl ester. Is more preferable.

The content of the structural unit (U1) derived from methyl methacrylate is preferably in the range of 50 to 95% by mass, preferably 70 to 90% by mass, based on all the structural units constituting the (meth) acrylic resin. More preferably, it is in the range.

Since the structural unit (U2) derived from phenylmaleimide has a relatively rigid structure, the coefficient of thermal expansion (CTE) of the functional layer can be reduced. Further, since the structural unit (U2) derived from phenylmaleimide has a relatively bulky structure, it may have microscopic voids in the resin matrix that can move the rubber particles. Therefore, the rubber particles can be used as the surface layer of the functional layer. It can be easily distributed unevenly in the part.

The content of the structural unit (U2) derived from phenylmaleimide is preferably in the range of 1 to 25% by mass with respect to all the structural units constituting the (meth) acrylic resin. When the content of the structural unit (U2) derived from phenylmaleimide is 1% by mass or more, the coefficient of thermal expansion (CTE) of the functional layer is easily reduced, and when it is 25% by mass or less, the brittleness of the functional layer is excessive. Is not easily damaged. From the above viewpoint, the content of the structural unit (U2) derived from phenylmaleimide is more preferably in the range of 7 to 15% by mass.

Since the structural unit (U3) derived from the acrylic acid alkyl ester can impart appropriate flexibility to the resin, for example, the brittleness due to containing the structural unit (U2) derived from phenylmaleimide can be improved.

The acrylic acid alkyl ester is preferably an acrylic acid alkyl ester having an alkyl moiety having 1 to 7 carbon atoms, preferably 1 to 5 carbon atoms. Examples of acrylic acid alkyl esters include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-hydroxyethyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate and the like.

The content of the structural unit (U3) derived from the acrylic acid alkyl ester is preferably in the range of 1 to 25% by mass with respect to all the structural units constituting the (meth) acrylic resin. When the content of the structural unit (U3) derived from the acrylic acid alkyl ester is 1% by mass or more, appropriate flexibility can be imparted to the (meth) acrylic resin, so that the functional layer does not become too brittle and breaks. Hateful. When the content of the structural unit (U3) derived from the acrylic acid alkyl ester is 25% by mass or less, the Tg of the functional layer does not become too low and the coefficient of thermal expansion (CTE) does not become too large. From the above viewpoint, the content of the structural unit (U3) derived from the acrylic acid alkyl ester is more preferably in the range of 5 to 15% by mass.

The ratio of the structural unit (U2) derived from phenylmaleimide to the total amount of the structural unit (U2) derived from phenylmaleimide and the structural unit (U3) derived from the acrylic acid alkyl ester is in the range of 20 to 70% by mass. It is preferable to have. When the ratio is 20% by mass or more, the tensile elastic modulus G2 of the functional layer is likely to be increased, and when it is 70% by mass or less, the functional layer is not too brittle.

The glass transition temperature (Tg) of the (meth) acrylic resin is preferably 100 ° C. or higher, and more preferably 120 to 150 ° C. When the Tg of the (meth) acrylic resin is within the above range, the heat resistance of the functional layer can be easily increased. In order to adjust the Tg of the (meth) acrylic resin, for example, it is preferable to adjust the content of the structural unit (U2) derived from phenylmaleimide and the structural unit (U3) derived from the acrylic acid alkyl ester.

The weight average molecular weight (Mw) of the (meth) acrylic resin is not particularly limited and can be adjusted according to the purpose. The weight average molecular weight of the (meth) acrylic resin is, for example, from the viewpoint of promoting entanglement of resin molecules to increase the toughness of the functional layer and making it difficult to break, and to appropriately increase the CTE ratio and curl to a degree preferable for adhesion. From the viewpoint of facilitating adjustment to the amount, it is preferably 100,000 or more, and more preferably 1 million or more. When the weight average molecular weight of the (meth) acrylic resin is 1 million or more, the toughness of the obtained functional layer can be enhanced. As a result, it is possible to prevent the functional layer from breaking due to the transfer tension when the film is transferred to the laminated film, and the transfer stability can be improved. From the same viewpoint, the weight average molecular weight of the (meth) acrylic resin is more preferably in the range of 1.5 million to 3 million. The method for measuring the weight average molecular weight is as described above.

<Fumaric acid diester resin>
The fumaric acid diester resin used for the functional layer is a fumaric acid diester resin containing a diisopropyl fumarate residue unit and a fumaric acid diester residue unit having an alkyl group having 1 or 2 carbon atoms.

Here, the alkyl groups having 1 or 2 carbon atoms in the fumaric acid diester residue unit having an alkyl group having 1 or 2 carbon atoms are independent of each other, and examples thereof include a methyl group and an ethyl group. Further, these may be substituted with a halogen group such as fluorine or chlorine; an ether group; an ester group or an amino group. Examples of the fumaric acid diester residue unit having an alkyl group having 1 or 2 carbon atoms include a dimethyl fumarate residue unit and a diethyl fumarate residue unit. Moreover, these may contain 1 type or 2 or more types.

Specific examples of the fumaric acid diester resin include diisopropyl fumarate / dimethyl fumarate copolymer resin and diisopropyl fumarate / diethyl fumarate copolymer resin.

The fumaric acid diester resin may contain other monomer residue units as long as it does not exceed the scope of the present invention, and examples of the other monomer residue units include styrene residue units. styrene residue units such as α-methylstyrene residue unit; (meth) acrylate residue unit; (meth) methyl acrylate residue unit, (meth) ethyl acrylate residue unit, (meth) butyl acrylate residue unit (Meta) acrylic acid ester residue unit such as residue unit; vinyl ester residue unit such as vinyl acetate residue unit, vinyl propionate residue unit; acrylonitrile residue unit; methacrylonyloryl residue unit; methyl Vinyl ether residue units such as vinyl ether residue unit, ethyl vinyl ether residue unit, butyl vinyl ether residue unit; N-methylmaleimide residue unit, N-cyclohexyl maleimide residue unit, N-phenylmaleimide residue unit, etc. -Substituted maleimide residue unit; olefin residue unit such as ethylene residue unit and propylene residue unit; or din-butyl fumarate residue unit, bis (2-ethylhexyl) fumarate residue unit and the like. One or more selected from the fumaric acid diester residue units other than the fumaric acid diester residue unit can be mentioned.

The blending ratio of the fumaric acid diester resin used in the present invention is in the range of 50 to 99 mol% of diisopropyl fumarate residue unit and 1 to 50 mol% of fumaric acid diester residue unit having an alkyl group having 1 or 2 carbon atoms. Fumaric acid having a range of 60 to 95 mol% of diisopropyl fumarate residue unit and an alkyl group having 1 or 2 carbon atoms is preferable because the range is preferable and the retardation characteristics and strength when used as a retardation film are excellent. A fumaric acid diester resin consisting of a diester residue unit in the range of 5 to 40 mol% is particularly preferable.

The fumaric acid diester resin used in the present invention preferably has a standard polystyrene-equivalent number average molecular weight in the range of 50,000 to 250,000 obtained from the elution curve measured by the gel permeation chromatography.

(Synthesis example of fumaric acid diester resin)
In a 1 L autoclave equipped with a stirrer, a cooling tube, a nitrogen introduction tube and a thermometer, 2 g of hydroxypropyl methylcellulose (manufactured by Shinetsu Chemical Co., Ltd., trade name: Metroz 60SH-50), 600 g of distilled water, 330 g of diisopropyl fumarate, 70 g of diethyl fumarate. , And 3 g of t-butylperoxypivalate as a polymerization initiator was added, and nitrogen bubbling was carried out for 1 hour, and then radical suspension polymerization was carried out by holding at 50 ° C. for 24 hours while stirring at 400 rpm. The suspension was cooled to room temperature, the suspension containing the produced polymer particles was filtered off, and washed with distilled water and methanol to obtain a fumaric acid diester resin (yield: 75%).
The number average molecular weight of the obtained fumaric acid diester resin was 120,000. Further, it was confirmed by 1H-NMR measurement that the resin composition was diisopropyl fumarate residue unit / diethyl fumarate residue unit = 84/16 (mol%).

<Polyimide resin>
The polyimide-based resin can be a polymerization reaction product of tetracarboxylic dianhydride and diamine.
The tetracarboxylic acid dianhydride may be any of aromatic tetracarboxylic acid dianhydride, aliphatic tetracarboxylic acid dianhydride, and alicyclic tetracarboxylic acid dianhydride, but aromatic tetracarboxylic acid dianhydride is preferable. It is an acid dianhydride. The diamine may be any of an aromatic diamine, an aliphatic diamine, and an alicyclic diamine, but is preferably an aromatic diamine.

The weight average molecular weight Mw of the polyimide resin is not particularly limited, but is preferably in the range of 100,000 to 300,000, preferably 130,000 to 250,000, from the viewpoint of increasing the toughness of the functional layer and making it difficult to break due to the conveying tension. It is more preferable that the range is. The method for measuring the weight average molecular weight Mw of the polyimide resin is the same as described above.

Among these, (meth) acrylic resin is preferable from the viewpoint of excellent translucency and less curing shrinkage.

The content of the resin in the functional layer is preferably 60% by mass or more, more preferably 70% by mass or more with respect to the functional layer.

[2.2] Additives The functional layer may further contain components other than the above, if necessary. Examples of other components include rubber particles, the above-mentioned matting agent (fine particles), a plasticizer, an ultraviolet absorber, and the like. Above all, since the functional layer containing the above-mentioned (meth) acrylic resin tends to be brittle, it is preferable to further contain rubber particles from the viewpoint of imparting toughness (suppleness).

<Rubber particles>
The rubber particles are particles containing a rubber-like polymer. The rubber-like polymer is a soft crosslinked polymer having a glass transition temperature of 20 ° C. or lower. Examples of such cross-linked polymers include butadiene-based cross-linked polymers, (meth) acrylic-based cross-linked polymers, and organosiloxane-based cross-linked polymers. Among them, the (meth) acrylic crosslinked polymer is preferable from the viewpoint that the difference in refractive index from the (meth) acrylic resin is small and the transparency of the functional layer is not easily impaired, and the acrylic crosslinked polymer (acrylic rubber-like weight) is preferable. Coalescence) is more preferable.

That is, the rubber particles are preferably particles containing the acrylic rubber-like polymer (a).

About acrylic rubber-like polymer (a):
The acrylic rubber-like polymer (a) is a crosslinked polymer containing a structural unit derived from an acrylic acid ester as a main component. "Included as a main component" means that the content of structural units derived from acrylic acid ester is in the range described later. The acrylic rubber-like polymer (a) has a structural unit derived from an acrylic acid ester, a structural unit derived from another monomer copolymerizable therewith, and two or more radically polymerizable groups in one molecule ( It is preferably a crosslinked polymer containing a structural unit derived from a polyfunctional monomer having a non-conjugated reactive double bond).

Acrylic acid esters include methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, sec-butyl acrylate, isobutyl acrylate, benzyl acrylate, cyclohexyl acrylate, 2-ethylhexyl acrylate, acrylic. An acrylic acid alkyl ester having 1 to 12 carbon atoms of an alkyl group such as n-octyl acid is preferable. The acrylic acid ester may be one kind or two or more kinds.

The content of the structural unit derived from the acrylic acid ester is preferably in the range of 40 to 80% by mass, preferably 50 to 80% by mass, based on all the structural units constituting the acrylic rubber-like polymer (a1). More preferably, it is in the range. When the content of the acrylic acid ester is within the above range, it is easy to impart sufficient toughness to the protective film.
The other copolymerizable monomer is a monomer copolymerizable with the acrylic acid ester other than the polyfunctional monomer. That is, the copolymerizable monomer does not have two or more radically polymerizable groups. Examples of copolymerizable monomers include methacrylic ester such as methyl methacrylate; styrenes such as styrene and methylstyrene; (meth) acrylonitrile; (meth) acrylamide; (meth) acrylic acid. .. Among them, the other copolymerizable monomer preferably contains styrenes. The other copolymerizable monomer may be one kind or two or more kinds.

The content of the structural unit derived from the other copolymerizable monomer is preferably in the range of 5 to 55% by mass with respect to the total structural unit constituting the acrylic rubber-like polymer (a). More preferably, it is in the range of 10 to 45% by mass.

Examples of polyfunctional monomers include allyl (meth) acrylate, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, diallyl malate, divinyl adipate, divinylbenzene, ethylene glycol di (meth) acrylate, and diethylene glycol (diethylene glycol). Includes meth) acrylates, triethylene glycol di (meth) acrylates, trimethylrol propanetri (meth) acrylates, tetromethylol methanetetra (meth) acrylates, dipropylene glycol di (meth) acrylates, polyethylene glycol di (meth) acrylates. ..

The content of the structural unit derived from the polyfunctional monomer is preferably in the range of 0.05 to 10% by mass with respect to all the structural units constituting the acrylic rubber-like polymer (a), and is 0. More preferably, it is in the range of 1 to 5% by mass. When the content of the polyfunctional monomer is 0.05% by mass or more, the degree of cross-linking of the obtained acrylic rubber-like polymer (a) is likely to be increased, so that the hardness and rigidity of the obtained functional layer are impaired. If it is not too much and is 10% by mass or less, the toughness of the functional layer is not easily impaired.

The monomer composition constituting the acrylic rubber-like polymer (a) can be measured by, for example, the peak area ratio detected by thermal decomposition GC-MS.

The glass transition temperature (Tg) of the rubber-like polymer is preferably 0 ° C. or lower, more preferably −10 ° C. or lower. When the glass transition temperature (Tg) of the rubber-like polymer is 0 ° C. or lower, appropriate toughness can be imparted to the film. The glass transition temperature (Tg) of the rubbery polymer is measured by the same method as described above.

The glass transition temperature (Tg) of the rubber-like polymer can be adjusted by the composition of the rubber-like polymer. For example, in order to lower the glass transition temperature (Tg) of the acrylic rubber-like polymer (a), an acrylic acid ester having an alkyl group having 4 or more carbon atoms in the acrylic rubber-like polymer (a) / It is preferable to increase the mass ratio of other copolymerizable monomers (for example, 3 or more, preferably in the range of 4 to 10).

The particles containing the acrylic rubber-like polymer (a) are the particles made of the acrylic rubber-like polymer (a) or the hard layer made of the hard crosslinked polymer (c) having a glass transition temperature of 20 ° C. or higher. , Particles having a soft layer made of the acrylic rubber-like polymer (a) arranged around the particles (these are also referred to as “elastomers”); the acrylic rubber-like polymer (a). In the presence of, the particles may be particles made of an acrylic graft copolymer obtained by polymerizing a mixture of monomers such as a methacrylate ester in at least one stage. The particles made of the acrylic graft copolymer may be core-shell type particles having a core portion containing the acrylic rubber-like polymer (a) and a shell portion covering the core portion.

About core-shell type rubber particles containing acrylic rubber-like polymer:
(Core part)
The core portion contains an acrylic rubber-like polymer (a), and may further contain a hard crosslinked polymer (c), if necessary. That is, the core portion may have a soft layer made of an acrylic rubber-like polymer and a hard layer made of a hard crosslinked polymer (c) arranged inside the soft layer.

The crosslinked polymer (c) can be a crosslinked polymer containing a methacrylic acid ester as a main component. That is, the crosslinked polymer (c) includes a structural unit derived from a methacrylic acid alkyl ester, a structural unit derived from another monomer copolymerizable therewith, and a structural unit derived from a polyfunctional monomer. It is preferably a crosslinked polymer containing.

The alkyl methacrylate ester may be the alkyl methacrylate ester described above; the other copolymerizable monomer may be the styrenes or acrylic acid ester described above; the polyfunctional monomer may be. Examples thereof include those similar to those mentioned above as the polyfunctional monomer.

The content of the structural unit derived from the methacrylic acid alkyl ester can be in the range of 40 to 100% by mass with respect to all the structural units constituting the crosslinked polymer (c). The content of the structural unit derived from the other copolymerizable monomer can be in the range of 60 to 0% by mass with respect to the total structural unit constituting the other crosslinked polymer (c). The content of the structural unit derived from the polyfunctional monomer can be in the range of 0.01 to 10% by mass with respect to all the structural units constituting the other crosslinked polymer.

(Shell part)
The shell portion contains a methacrylic polymer (b) (another polymer) graft-bonded to the acrylic rubber-like polymer (a) and containing a structural unit derived from a methacrylic acid ester as a main component. Including as a main component means that the content of structural units derived from methacrylic acid ester is in the range described later.

The methacrylic acid ester constituting the methacrylic acid polymer (b) is preferably an alkyl methacrylate ester having 1 to 12 carbon atoms of an alkyl group such as methyl methacrylate. The methacrylic acid ester may be one kind or two or more kinds.

The content of the methacrylic acid ester is preferably 50% by mass or more with respect to all the structural units constituting the methacrylic acid polymer (b). When the content of the methacrylate ester is 50% by mass or more, compatibility with a methacrylic resin containing a structural unit derived from methyl methacrylate as a main component can be easily obtained. From the above viewpoint, the content of the methacrylic acid ester is more preferably 70% by mass or more with respect to all the structural units constituting the methacrylic polymer (b).

The methacrylic polymer (b) may further contain a structural unit derived from another monomer copolymerizable with the methacrylic ester. Examples of other copolymerizable monomers are acrylic acid esters such as methyl acrylate, ethyl acrylate, n-butyl acrylate; benzyl (meth) acrylate, dicyclopentanyl (meth) acrylate, A (meth) acrylic monomer having an alicyclic, heterocyclic or aromatic ring such as phenoxyethyl (meth) acrylate (ring-containing (meth) acrylic monomer) is included.

The content of the structural unit derived from the copolymerizable monomer is preferably 50% by mass or less, preferably 30% by mass or less, based on all the structural units constituting the methacrylic polymer (b). Is more preferable.

The ratio of the graft component (graft ratio) in the rubber particles is preferably in the range of 10 to 250% by mass, and more preferably in the range of 15 to 150% by mass. When the graft ratio is above a certain level, the proportion of the graft component, that is, the methacrylic polymer (b) containing the structural unit derived from the methacrylic acid ester as the main component is moderately large, so that the rubber particles and the methacrylic resin are separated from each other. It is easy to improve compatibility and it is more difficult to agglomerate rubber particles. In addition, the rigidity of the film is not easily impaired. When the graft ratio is below a certain level, the proportion of the acrylic rubber-like polymer (a) does not become too small, so that the toughness and brittleness improving effect of the functional layer are not easily impaired.

The graft ratio is measured by the following method.

1) Dissolve 2 g of core-shell type particles in 50 mL of methyl ethyl ketone and centrifuge at a rotation speed of 30,000 rpm and a temperature of 12 ° C. for 1 hour using a centrifuge (manufactured by Hitachi Koki Co., Ltd., CP60E) to make it insoluble. Separate into the dissolved components (centrifugal separation work is set 3 times in total).

2) Calculate the graft ratio by applying the weight of the obtained insoluble matter to the following formula.

Graft ratio (mass%) = [{(mass of methyl ethyl ketone insoluble matter)-(mass of acrylic rubber-like polymer (a))} / (mass of acrylic rubber-like polymer (a))] × 100
In the present embodiment, since the functional layer is not stretched, the shape of the rubber particles can be a shape close to a true sphere. That is, the aspect ratio of the rubber particles when observing the cross section or the surface of the functional layer can be about 1 to 2.

The average particle size of the rubber particles is preferably in the range of 100 to 400 nm. When the average particle size of the rubber particles is 100 nm or more, sufficient toughness and stress relaxation property are easily imparted to the functional layer, and when it is 400 nm or less, the transparency of the functional layer is not easily impaired. From the same viewpoint, the average particle size of the rubber particles is more preferably in the range of 150 to 300 nm.

The average particle size of the rubber particles can be calculated by the following method.

The average particle size of the rubber particles can be measured as the average value of the equivalent circle diameters of 100 particles obtained by SEM or TEM photography of the surface or section of the laminated film. The equivalent circle diameter can be obtained by converting the projected area of the particles obtained by photographing into the diameter of a circle having the same area. At this time, the rubber particles observed by SEM observation and / or TEM observation at a magnification of 5000 times are used for calculating the average particle size.

The content of the rubber particles is not particularly limited, but is preferably in the range of 5 to 40% by mass, and more preferably in the range of 7 to 30% by mass with respect to the functional layer.

(Distribution of rubber particles)
The rubber particles may be uniformly dispersed in the thickness direction of the functional layer, or may be unevenly distributed. Specifically, in the cross section along the thickness direction of the functional layer, the area of 20% or less of the thickness of the functional layer from the surface opposite to the support of the functional layer is the area A and the support side of the functional layer. 20% or less of the area of the thickness from the surface functional layer and area B, and area ratio per unit area of the rubber particles in the region a R _a, the area ratio per unit area of the rubber particles in the region B and R _B When this _{is done, it is preferable that RA} / R _B is in the range of 1.0 to 1.1.

Above all, from the viewpoint of making it difficult to generate stress when the laminated film is curled and improving the adhesiveness with the polarizer layer, the rubber particles are the surface layer portion of the functional layer (the surface layer portion on the opposite side to the support). It is preferable that the particles are unevenly distributed. _{Specifically, the RA} / R _B of the functional layer is more preferably in the range of 1.04 to 1.06. When R _A / R _B is 1.04 or more, the rubber particles are unevenly distributed on the surface layer portion of the functional layer. Therefore, since the flexibility and toughness of the surface layer portion of the functional layer can be increased, as shown in FIG. 1B, when the functional layer is curled so as to be on the outside, it is easy to follow the curl, and stress is generated due to the curl. Can be reduced. When _RA / R _B is 1.1 or less, the difference in toughness between the surface layer portion and the inside of the functional layer does not become too large, so that cracks are unlikely to occur during transportation due to the stress difference.

_{The area ratio RA} per unit area of the rubber particles in the region A is expressed by the following formula.

Area ratio _RA (%) = total area of rubber particles in region A / area of region A x 100
Area ratio R _B per unit area of the rubber particles in the area B is similarly defined.

_{The RA} / R _B of the functional layer can be measured by the following method.

1) Cut the functional layer with a microtome, and observe the cut surface perpendicular to the surface of the functional layer by TEM. The observation conditions may be acceleration voltage (electron energy irradiating the sample): 30 kV, working distance (distance between the lens and the sample): 8.6 mm × magnification: 3.00 k. The observation area is a region including the entire functional layer in the thickness direction.

2) The obtained TEM image is subjected to an opening process after removing the brightness gradient using image processing software of NiVision (manufactured by National Instruments), and the contrast difference between the bulk and the rubber particles is detected. Thereby, the distribution state of the rubber particles is specified.

3) In the image after image processing obtained in 2) above, the area ratio _RA per unit area of the rubber particles in the region A and the area per unit area of the rubber particles in the region B in the thickness direction of the functional layer. Calculate the rate R _{B respectively.}

_{4) R A} / R _B is calculated from the result obtained in 3) above.

The method of unevenly distributing the rubber particles is not particularly limited, but can be adjusted by the drying conditions (drying speed, etc.) of the applied functional layer solution and the composition of the (meth) acrylic resin. In order to facilitate uneven distribution of rubber particles on the surface layer portion (region A) of the functional layer, it is preferable to increase the drying rate, as will be described later; in order to increase the drying rate, the drying temperature is increased. Is preferable. Further, the (meth) acrylic resin containing a moderately large amount of structural unit (U2) derived from phenylmaleimide has many microscopic voids and easily diffuses and moves rubber particles. Therefore, the structural unit derived from phenylmaleimide is used. By appropriately increasing the content of (U2), it is possible to make it easier for the rubber particles to be unevenly distributed.

[2.3] Physical Properties The functional layer according to the present invention can function as an optical film such as a retardation film by being peeled off from a base film and then bonded to a polarizer layer.

<Phase difference Ro and Rt>
From the viewpoint of using the functional layer as a retardation film for IPS mode, for example, the in-plane retardation Ro measured in an environment of a measurement wavelength of 590 nm, a temperature of 23 ° C., and a humidity of 55% RH is in the range of 0 to 10 nm. It is preferably in the range of 0 to 5 nm, and more preferably in the range of 0 to 5 nm. The phase difference Rt in the thickness direction of the functional layer is preferably in the range of -40 to 40 nm, and more preferably in the range of -25 to 25 nm.

Ro and Rt are defined by the following formulas, respectively.

Equation (a): Ro = (n _{x −} n _y ) × d
Equation (b): Rt = ((n _x + n _y ) /2- _nz ) × d
(During the ceremony,
n _x represents the refractive index in the in-plane slow-phase axial direction (the direction in which the refractive index is maximized) of the functional layer.
n _y represents the refractive index in the direction orthogonal to the in-plane slow phase axis of the functional layer.
n _z represents the refractive index of the functional layer in the thickness direction.
d represents the thickness (nm) of the functional layer. )
The in-plane slow-phase axis of the functional layer can be confirmed by an automatic birefringence meter Axoscan (Axo Scan Mueller Matrix Polarimeter: manufactured by Axometrics).

Ro and Rt can be measured by the following methods.

1) Humidity control of the functional layer for 24 hours in an environment with a temperature of 23 ° C and a humidity of 55% RH. The average refractive index of this film is measured with an Abbe refractometer, and the thickness d is measured with a commercially available micrometer.

2) The retardation Ro and Rt of the film after humidity control at a measurement wavelength of 590 nm were measured at a temperature of 23 ° C. and a humidity of 55 using an automatic birefringence meter Axoscan (AxoScan Mueller Matrix Polarimeter: manufactured by Axometrics). Measured in an environment of% RH.

The phase difference Ro and Rt of the functional layer can be adjusted, for example, by the type of resin, stretching conditions, and drying conditions. For example, Rt can be lowered by raising the drying temperature.

[3] Method for Producing Laminated Film The form of the laminated film (laminated body of the base film and the functional layer) of the present invention is not particularly limited, but may be band-shaped, for example. That is, it is preferable that the laminated film of the present invention is wound into a roll in a direction orthogonal to the width direction to form a roll.

[Production method]
The method for producing a laminated film of the present invention includes 1) a step of obtaining a solution for a functional layer, 2) a step of applying the obtained functional layer solution to the surface of a base film, and 3) a step of applying the obtained functional layer solution to the surface of the base film. It may be a method of forming a film on a substrate having a step of removing a solvent from a solution to form a functional layer, or a method of simultaneously laminating a film using a laminated die in the above solution film forming method. However, from the viewpoint of the flatness of the functional layer, a method of forming a film on the substrate is preferable.

1) Step of obtaining a solution for a functional layer A solution for a functional layer containing the above-mentioned resin and a solvent is prepared.

The solvent used for the solution for the functional layer is not particularly limited as long as it can disperse or dissolve the resin well. Examples of solvents include alcohols such as methanol, ethanol, propanol, n-butanol, 2-butanol, tert-butanol and cyclohexanol, ketones such as methyl ethyl ketone, methyl isobutyl ketone and acetone, ethyl acetate, methyl acetate and lactic acid. Esters such as ethyl, isopropyl acetate, amyl acetate, ethyl butyrate, glycol ethers (propylene glycol mono (C1 to C4) alkyl ethers (specifically, propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether, propylene glycol) Mono-n-propyl ether, propylene glycol monoisopropyl ether, propylene glycol monobutyl ether, etc.), propylene glycol mono (C1-C4) alkyl ether esters (propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate)), toluene, benzene , Cyclohexane, n-hexane and other hydrocarbons are included. It is preferable to contain ketones from the viewpoint of easily dissolving the resin, having a low boiling point, and easily increasing the drying speed and productivity, and further containing alcohols from the viewpoint of easily forming a functional layer having high flatness. preferable.

That is, the solvent preferably contains ketones and alcohols. The content ratio of ketones and alcohols is not particularly limited, but from the viewpoint of achieving both drying speed and flatness, ketones / alcohols = 95/5 to 60/40 (mass ratio) is preferable. , 95/5 to 80/20 (mass ratio), more preferably. When the proportion of ketones is moderately high, the drying property and productivity are likely to be improved, and when the proportion of alcohols is moderately high, the flatness is not easily impaired.

The resin concentration of the solution for the functional layer is preferably in the range of 1.0 to 20% by mass, for example, from the viewpoint of facilitating the adjustment of the viscosity to the range described later. Further, from the viewpoint of reducing the amount of shrinkage during drying of the coating film, the resin concentration of the solution for the functional layer is preferably moderately high, more preferably more than 5% by mass and 20% by mass or less, and more than 5% by mass. It is more preferably 15% by mass or less.

The viscosity of the solution for the functional layer may be such that a functional layer having a desired thickness can be formed, and is not particularly limited, but is preferably in the range of, for example, 5 to 5000 mPs · s. When the viscosity of the solution for the functional layer is 5 cP or more, it is easy to form a functional layer having an appropriate thickness, and when it is 5000 mPs · s or less, it is possible to suppress the occurrence of thickness unevenness due to the increase in the viscosity of the solution. From the same viewpoint, the viscosity of the solution for the functional layer is more preferably in the range of 100 to 1000 mPs · s. The viscosity of the solution for the functional layer can be measured with an E-type viscometer at 25 ° C.

2) Step of applying the functional layer solution Next, the obtained functional layer solution is applied to the surface of the base film. Specifically, the obtained solution for the functional layer is applied to the surface of the base film.

The method for applying the solution for the functional layer is not particularly limited, and may be, for example, a known method such as a back roll coating method, a gravure coating method, a spin coating method, a wire bar coating method, or a roll coating method. Above all, the back coat method is preferable from the viewpoint of being able to form a thin and uniform thickness coating film.

3) Step of forming the functional layer Next, the solvent is removed from the solution for the functional layer applied to the support to form the functional layer.

Specifically, the solution for the functional layer applied to the support is dried. Drying can be performed, for example, by blowing air or heating. Above all, from the viewpoint of facilitating curling of the laminated film, it is preferable to dry the laminated film by blowing air.

By adjusting the drying conditions (for example, drying temperature, drying air volume, drying time, etc.), for example, when the functional layer contains rubber particles, the distribution state of the rubber particles can be adjusted. Specifically, from the viewpoint of facilitating uneven distribution of rubber particles, the drying rate of the coating film of the solution for the functional layer containing the (meth) acrylic resin and the rubber particles is preferably high, and 0.0015 to 0. it is preferably in the range of .05kg / hr · m ^2, and more preferably in the range of ^{0.002 ~ 0.05kg / hr · m 2} .

The drying rate is expressed as the mass of the solvent that evaporates per unit time and unit area. The drying rate can usually be adjusted by the drying temperature. The drying temperature may be, for example, in the range of 50 to 200 ° C. ((Tb-50) to (Tb + 50) ° C. with respect to the boiling point of the solvent used), although it depends on the solvent type used.

The laminated film according to the present embodiment may be strip-shaped as described above. Therefore, it is preferable that the method for producing a laminated film according to the present embodiment further includes 4) a step of winding a strip-shaped laminated film into a roll to form a roll.

4) Step of winding the laminated film to obtain a roll body The obtained strip-shaped laminated film is wound into a roll shape in a direction orthogonal to the width direction thereof to form a roll body.

The length of the strip-shaped laminated film is not particularly limited, but may be, for example, about 100 to 10000 m. The width of the strip-shaped laminated film is preferably 1 m or more, and more preferably 1.3 to 4 m.

[manufacturing device]
The method for producing a laminated film of the present invention can be performed by, for example, the production apparatus shown in FIG.

FIG. 3 is a schematic view of a manufacturing apparatus B200 for carrying out the method for manufacturing a laminated film according to the present embodiment. The manufacturing apparatus B200 includes a supply unit B210, a coating unit B220, a drying unit B230, a cooling unit B240, and a winding unit B250. Ba to Bd indicate transport rolls for transporting the base film B110.

The supply unit B210 has a feeding device (not shown) for feeding out the roll body B201 of the strip-shaped base film B110 wound around the winding core.

The coating unit B220 is a coating device, and includes a backup roll B221 that holds the base film B110, a coating head B222 that applies a solution for a functional layer to the base film B110 held by the backup roll B221, and a coating head. It has a decompression chamber B223 provided on the upstream side of B222.

The flow rate of the functional layer solution discharged from the coating head B222 can be adjusted by a pump (not shown). The flow rate of the functional layer solution discharged from the coating head B222 is set to an amount capable of stably forming a coating layer having a predetermined layer thickness when continuously coated under the conditions of the coating head B222 adjusted in advance.

The decompression chamber B223 is a mechanism for stabilizing the bead (pool of coating liquid) formed between the solution for the functional layer from the coating head B222 and the base film B110 at the time of coating, and the degree of decompression can be adjusted. It has become. The decompression chamber B223 is connected to a decompression blower (not shown) so that the inside is decompressed. The pressure reducing chamber B223 is in a state where there is no air leakage, and the gap between the pressure reducing chamber B223 and the backup roll is narrowly adjusted so that a stable bead of the coating liquid can be formed.

The drying unit B230 is a drying device that dries the coating film applied to the surface of the base film B110, and has a drying chamber B231, a drying gas introduction port B232, and a discharge port B233. The temperature and air volume of the dry air are appropriately determined depending on the type of the coating film and the type of the base film B110. By setting conditions such as the temperature and air volume of the drying air and the drying time in the drying unit B230, the residual solvent content of the coating film after drying can be adjusted. The amount of residual solvent in the coating film after drying can be measured by comparing the unit mass of the coating film after drying with the mass after the coating film is sufficiently dried.

(Amount of residual solvent)
Since the functional layer is obtained by applying a solution for the functional layer, a solvent derived from the solution may remain. The amount of residual solvent is preferably 700 ppm or less, more preferably 30 to 700 ppm with respect to the functional layer. The content of the residual solvent can be adjusted by the drying conditions of the solution for the functional layer applied on the base film in the manufacturing process of the functional layer.

The amount of residual solvent in the functional layer can be measured by headspace gas chromatography. In the headspace gas chromatography method, a sample is sealed in a container, heated, and the gas in the container is promptly injected into a gas chromatograph with the container filled with volatile components, and mass analysis is performed to identify the compound. The volatile components are quantified while doing so. The headspace method makes it possible to observe all peaks of volatile components by gas chromatography, and by using an analytical method that utilizes electromagnetic interactions, it is possible to quantify volatile substances and monomers with high accuracy. It can be done at the same time.

The cooling unit B240 cools the temperature of the base film B110 having the coating film (functional layer B120) obtained by drying in the drying unit B230, and adjusts the temperature to an appropriate temperature. The cooling unit B240 has a cooling chamber B241, a cooling air inlet B242, and a cooling air outlet B243. The temperature and air volume of the cooling air can be appropriately determined depending on the type of the coating film and the type of the base film B110. Further, even if the cooling unit B240 is not provided, the cooling unit B240 may not be provided if the cooling temperature is appropriate.

The winding unit B250 is a winding device (not shown) for winding the base film B110 on which the transparent functional layer B120 is formed to obtain the roll body B251.

[4] Polarizing plate The polarizing plate has a polarizing element layer and a laminated film or functional layer of the present invention arranged on at least one surface thereof. It is preferable that the polarizer layer and the laminated film or the functional layer are adhered to each other via an adhesive layer.

FIG. 4 shows an example of the layer structure of the polarizing plate of the present invention, but the present invention is not limited thereto.

FIG. 4A is a cross-sectional view of a polarizing plate with a base film.
The functional layer 3 side of the laminated film 1 (base film 2 and functional layer 3) of the present invention is bonded to the polarizer layer 5 via the adhesive layer 4 to process the polarizing plate 10a. If necessary, the opposing film 6 may be bonded to the surface of the polarizer layer 5 opposite to the surface to which the laminated film 1 of the present invention is bonded, via the adhesive layer 4.

When the polarizing plate 10a is provided in a display device (not shown), for example, the laminated film 1 of the present invention may be bonded to the display element side via an adhesive layer (not shown), or the display element. The facing film 6 may be attached to the side via an adhesive layer (not shown). When the laminated film 1 of the present invention is bonded, it is preferably the embodiment shown in FIG. 4 (b) below in which the base film 2 is peeled off from the laminated film 1.

FIG. 4B is a cross-sectional view of a polarizing plate from which the base film has been peeled off.
The functional layer 3 side of the laminated film 1 (base film 2 and functional layer 3) of the present invention is bonded to the polarizer layer 5 via the adhesive layer 4 to process the polarizing plate 10b. The base film 2 is peeled from the functional layer 3 during or after the polarizing plate processing to process the thin polarizing plate 10b. If necessary, the opposing film 6 may be bonded to the surface of the polarizer layer 5 opposite to the surface to which the functional layer 3 according to the present invention is bonded, via the adhesive layer 4.

When the polarizing plate 10b is provided in a display device (not shown), for example, the functional layer 3 according to the present invention may be attached to the display element side via an adhesive layer (not shown), and the polarizing plate 10b may be displayed. The facing film 6 may be attached to the element side via an adhesive layer (not shown).

[4.1] Polarizer layer The polarizing layer is an element that allows only light on the plane of polarization in a certain direction to pass through. The polarizer layer can usually be a polyvinyl alcohol-based polarizing film. Examples of the polyvinyl alcohol-based polarizing film include a polyvinyl alcohol-based film dyed with iodine and a film dyed 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 bicolor dye (preferably a film further subjected to a durability treatment with a boron compound); polyvinyl. An alcohol-based film may be a film that has been dyed with iodine or a bicolor dye and then uniaxially stretched (preferably a film that has been further subjected to a durability treatment with a boron compound). The absorption axis of the polarizer layer is usually parallel to the maximum stretching direction.

The thickness of the polarizing element layer is preferably in the range of 5 to 30 μm, and more preferably in the range of 5 to 20 μm from the viewpoint of thinning the polarizing plate.

[4.2] Laminated Film or Functional Layer, and Opposite Film A base film or functional layer constituting the laminated film of the present invention is arranged on at least one surface of the polarizer layer. Any of the base film or the functional layer constituting the laminated film can function as a polarizer layer protective film. In the present embodiment, it is preferable that the functional layer is arranged on one surface of the polarizer layer and the other protective film is arranged on the other surface.

Examples of the opposing film include a cycloolefin resin, a polypropylene resin, an acrylic resin, a polyester resin, a polyarylate resin, a cellulose ester resin, a styrene resin, or a composite resin thereof. Above all, it is preferable to contain a cycloolefin resin, an acrylic resin and a polyester resin.

[4.3] Adhesive layer The adhesive layer is arranged between the functional layer and the polarizer layer, and between the opposing film and the polarizer layer, respectively. The adhesive layer arranged between the functional layer and the polarizer layer and the adhesive layer arranged between the opposing film and the polarizer layer may be the same or different.

The adhesive layer may be a layer obtained from a water-soluble polymer or a cured product layer of an active energy ray-curable adhesive. In the case of a water-soluble polymer, for example, via an adhesive made of a vinyl alcohol-based polymer, or at least an adhesive made of a water-soluble cross-linking agent of a vinyl alcohol-based polymer such as boric acid, borosand, glutaaldehyde, melamine, and oxalic acid. Can be done. Such an adhesive layer is formed as a coating dry layer of an aqueous solution or the like, but when preparing the aqueous solution, other additives or a catalyst such as an acid can be added as needed.

The active energy ray-curable adhesive may be a photoradical polymerizable composition or a photocationic polymerizable composition. Of these, a photocationically polymerizable composition is preferable.

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

The epoxy compound is a compound having one or more, preferably two or more epoxy groups in the molecule. Examples of epoxy compounds include hydride epoxy compounds obtained by reacting an alicyclic polyol with epichlorohydrin (glycidyl ether of a polyol having an alicyclic ring); an aliphatic polyhydric alcohol or an alkylene thereof. Aliphatic epoxy compounds such as polyglycidyl ether as an oxide adduct; alicyclic epoxy compounds having one or more epoxy groups bonded to an alicyclic ring in the molecule are included. Only one type of epoxy compound may be used, or two or more types may be used in combination.

The photocationic polymerization initiator may be, for example, an aromatic diazonium salt; an onium salt such as an aromatic iodonium salt or an aromatic sulfonium salt; an iron-alene complex or the like.

Photocationic polymerization initiators include cationic polymerization accelerators such as oxetane and polyols, photosensitizers, ion trapping agents, antioxidants, chain transfer agents, tackifiers, thermoplastic resins, fillers, and fluids, as required. Additives such as modifiers, plasticizers, defoamers, antistatic agents, leveling agents, solvents and the like may be further included.

The thickness of the adhesive layer is not particularly limited, but is preferably in the range of 0.01 to 10 μm, and more preferably in the range of 0.01 to 5 μm.

[4.4] Adhesive Layer The adhesive layer is a layer for bonding a polarizing plate to a display element such as a liquid crystal cell, and may be arranged on a surface of the functional layer opposite to the polarizer layer. Alternatively, it can be arranged on the surface of the opposing film.

The pressure-sensitive adhesive layer is preferably a pressure-sensitive adhesive composition containing a base polymer, a prepolymer and / or a cross-linking monomer, a cross-linking agent and a solvent, which is dried and partially cross-linked. That is, at least a part of the pressure-sensitive adhesive composition may be crosslinked.

Examples of the pressure-sensitive adhesive composition include an acrylic pressure-sensitive adhesive composition using a (meth) acrylic polymer as a base polymer, a silicone-based pressure-sensitive adhesive composition using a silicone-based polymer as a base polymer, and a rubber-based pressure-sensitive adhesive composition using a rubber as a base polymer. A pressure-sensitive adhesive composition is included. Above all, an acrylic pressure-sensitive adhesive composition is preferable from the viewpoint of transparency, weather resistance, heat resistance, and processability.

The (meth) acrylic polymer contained in the acrylic pressure-sensitive adhesive composition can be a copolymer of a (meth) acrylic acid alkyl ester and a cross-linking agent and a cross-linkable functional group-containing monomer.

The (meth) acrylic acid alkyl ester is preferably an acrylic acid alkyl ester having 2 to 14 carbon atoms in the alkyl group.

Examples of the functional group-containing monomer that can be crosslinked with the cross-linking agent include an amide group-containing monomer, a carboxyl group-containing monomer (acrylic acid, etc.), and a hydroxyl group-containing monomer (hydroxyethyl acrylate, etc.).

Examples of the cross-linking agent contained in the acrylic pressure-sensitive adhesive composition include an epoxy-based cross-linking agent, an isocyanate-based cross-linking agent, and a peroxide-based cross-linking agent. The content of the cross-linking agent in the pressure-sensitive adhesive composition can usually be in the range of, for example, 0.01 to 10 parts by mass with respect to 100 parts by mass of the base polymer (solid content).

Adhesive compositions include tackifiers, plasticizers, fiberglass, glass beads, metal powders, other fillers, pigments, colorants, fillers, antioxidants, UV absorbers, silane couplings as needed. Various additives such as agents may be further included.

The thickness of the pressure-sensitive adhesive layer is usually about 3 to 100 μm, preferably in the range of 5 to 50 μm.

The surface of the adhesive layer is protected by a release film that has undergone a mold release treatment. Examples of the release film include a plastic film such as an acrylic film, a polycarbonate film, a polyester film, and a fluororesin film.

[4.5] Method for Manufacturing a Polarizing Plate In the polarizing plate according to the present embodiment, the above-mentioned laminated film is attached to at least one surface of the polarizer layer, and the base film is peeled off if necessary. It can be manufactured through a process. The laminated film may be bonded to only one surface of the polarizing element layer or both surfaces, and from the viewpoint of optical characteristics such as transmittance and phase difference and curling suppression, the polarizing element layer may be bonded. It is preferable that the laminated film is attached to one surface and the opposing film, which is another protective film, is attached to the other surface.

Further, the base film side of the laminated film of the present invention may be bonded to the polarizer layer, or the functional layer side may be bonded. Preferably, the functional layer side is bonded and the base film is used as a protective film, or the base film is peeled off and only the functional layer of the thin film is used.

Therefore, when the laminated film is wound while being bonded to at least one surface of the polarizing element layer to produce a roll-shaped polarizing plate (also referred to as “polarizing plate roll”), the polarizing element layer is formed from the inside of the roll. It is a preferable method for producing a polarizing plate roll to include a step of winding the laminated film while adhering it to the polarizing element layer so that the order of the adhesive layer, the functional layer and the base material fill is arranged.

Basically, the polarizing plate according to the present invention is 1) a step of laminating the functional layer side of the laminated film on one surface of the polarizing element layer (arranged on the surface opposite to the polarizing element layer of the functional layer). The base film may be left attached or peeled off if necessary.) 2) An opposing film, which is another protective film, is attached to the other surface of the polarizing element layer. It can be manufactured through a process.

1) Laminating step of the functional layer The functional layer side of the laminated film is bonded to one surface of the polarizing element layer via an adhesive. If necessary, a pretreatment such as a corona treatment may be applied to the surface of the functional layer to be bonded or one surface of the polarizer layer.

For example, when a water-soluble polymer adhesive is used as the adhesive, 1) the surface of the functional layer of the laminated film is subjected to surface treatment such as corona treatment, if necessary. Next, the functional layer of the laminated film is laminated on one surface of the polarizer layer via an adhesive of a water-soluble polymer.
2) Step of pasting the opposing film, which is another protective film, on the other surface of the polarizer layer Next, the opposing film, which is another protective film, is bonded to the other surface of the polarizer layer. Specifically, the surface of the opposing film is subjected to a surface treatment such as a corona treatment, if necessary. Next, the opposing film is laminated on the other surface of the polarizer layer via an adhesive of a water-soluble polymer, and then a stepwise drying treatment is performed in a temperature range of, for example, 50 to 80 ° C.

The steps 1) and 2) may be performed simultaneously or sequentially. From the viewpoint of increasing production efficiency, it is preferable to perform the steps 1) and 2) at the same time.

The polarizing plate according to the present embodiment may be band-shaped. Therefore, in the steps 1) and 2), the functional layer of the strip-shaped laminated film, the strip-shaped polarizing element layer, and the other strip-shaped protective film (opposing film) are unwound from the roll body to roll. It is preferable to perform the polarizing plate processing by laminating with a to roll.

Further, it is preferable to further perform the step of winding the strip-shaped polarizing plate into a roll shape to form a roll body. In this step, the length and width of the strip-shaped polarizing plate are the same as the length and width of the strip-shaped laminated film in the step 4) of the method for manufacturing a laminated film.

Further, in the method for producing a polarizing plate roll of the present invention, in the step of winding the laminated film 1 while adhering it to at least one surface of the polarizing layer 5, the polarizing layer 5 and the adhesive layer 4 are formed from the inside of the roll. It is also preferable to form a polarizing plate roll by a step of winding the laminated film 1 while adhering it to the polarizing element layer 5 so that the functional layer 3 and the base material fill 2 are layered in this order. In this case, since the base film 2 according to the present invention is arranged on the outside of the polarizing plate roll, it exhibits a function as a protective film and prevents scratches or the like on the functional layer 2 during polarizing plate processing. Or, curling can be suppressed to facilitate handling.

At this time, if necessary, the opposing film 6 is wound on the surface opposite to the surface on which the laminated film 1 is bonded while being bonded to the polarizing layer 5 via the adhesive layer 4, and the polarizing plate roll is used. May be formed.

[5] Display device The display device according to the present embodiment includes a display element such as a liquid crystal cell or an organic electroluminescence (also referred to as "EL") element, and a polarizing plate manufactured by the above manufacturing method. Above all, the display device according to the present embodiment is preferably a liquid crystal display device having a liquid crystal cell and a polarizing plate manufactured by the above manufacturing method.

That is, the liquid crystal display device includes a liquid crystal cell, a first polarizing plate arranged on one surface of the liquid crystal cell, and a second polarizing plate arranged on the other surface of the liquid crystal cell. Then, at least one of the first polarizing plate and the second polarizing plate is the polarizing plate according to the present embodiment. It is preferable that the absorption axis of the first polarizing element layer in the first polarizing plate and the absorption axis of the second polarizer layer in the second polarizing plate are orthogonal to each other (cross Nicol).

The display modes of the liquid crystal cells are, for example, STN (Super-Twisted Nematic), TN (Twisted Nematic), OCB (Optically Compensated Bend), HAN (Hybridrated Nematic), VA (Vertic), and VA (Vertic). (Patterned Vertical Element)), IPS (In-Plane-Switching), and the like. For example, in a liquid crystal display device for mobile devices, the IPS mode is preferable.

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. In the examples, the indication of "parts" or "%" is used, but unless otherwise specified, it indicates "parts by mass" or "% by mass".

1. 1. Material of base film (1) Cycloolefin resin (COP1)
As the cycloolefin resin, ARTON / RX4500 manufactured by JSR Corporation was used.

(2) Polyarylate resin (PAR)
As the polyarylate resin, U-100 manufactured by Unitika Ltd. was used.

(3) Styrene / (meth) acrylate copolymer (MS)
TX320XL manufactured by Denka Co., Ltd. was used as the styrene / (meth) acrylate copolymer.

(4) Styrene-hydroxystyrene copolymer (CST)
Maruzen Petrochemical Co., Ltd. Maruka Linker CST50 was used as the styrene / hydroxystyrene copolymer.

(5) Cycloolefin resin (COP2)
As a comparative cycloolefin resin, ZF14 manufactured by Nippon Zeon Corporation was used.

(6) Triacetyl Cellulose Resin (TAC)
As a comparative triacetyl cellulose-based resin, acetyl cellulose having an acetyl substitution degree of 2.9 was used.

(7) Polymethylmethacrylate resin (PMMA)
As a comparative polymethylmethacrylate resin, 80N manufactured by Asahi Kasei Corporation was used.
(8) Polycarbonate resin (PC)
As the polycarbonate resin, Panlite K1300Y manufactured by Teijin Chemical Industries, Ltd. was used.

2. Preparation of base film <Production of base film 1>
(Preparation of fine particle additive liquid)
Fine particles (Aerosil R812: manufactured by Nippon Aerosil Co., Ltd., primary average particle size: 7 nm, apparent specific gravity 50 g / L) 4 parts by mass dichloromethane 48 parts by mass Ethanol 48 parts by mass or more is stirred and mixed with a dissolver for 50 minutes, and then dispersed with manton gorin. went. Further, the particles were dispersed by an attritor so that the particle size of the secondary particles became a predetermined size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution.

(Preparation of dope)
A dope having the following composition was prepared. First, dichloromethane and ethanol were added to the pressurized dissolution tank. Cycloolefin resin (DOP1): RX4500 was put into a pressurized dissolution tank containing a mixed solution of dichloromethane and ethanol with stirring. Further, 15 minutes after the start of solvent addition, the fine particle-added solution prepared above was added, and the mixture was heated to 80 ° C. and completely dissolved while stirring. At this time, the temperature was raised from room temperature to 5 ° C./min, dissolved in 30 minutes, and then lowered to 3 ° C./min. The obtained solution was used as Azumi Filter Paper No. 1 manufactured by Azumi Filter Paper Co., Ltd. Filtration was performed using 244 to prepare a dope.

(Doping composition)
Cycloolefin resin (RX4500) 100 parts by mass Dichloromethane 200 parts by mass Ethanol 10 parts by mass 1 part by mass Fine particle addition liquid Next, using an endless belt casting device, dope is uniformly flowed on a stainless steel belt at a temperature of 31 ° C. and a width of 1800 mm. It was postponed. The temperature of the stainless belt was controlled to 20 ° C. Then, the solvent was evaporated on the stainless steel belt until the amount of residual solvent in the cast film reached 100% by mass, and the cast film (base film) was peeled off from the stainless steel belt. At the time of peeling, the base film was stretched 1.2 times in the transport direction to shrink 15% in the width direction, and then stretched 1.5 times in the width direction under the condition of 160 ° C. The amount of residual solvent at the start of stretching was 15% by mass.

Next, the base film was dried at 120 ° C. for 15 minutes while being conveyed by a large number of rollers in the drying zone, and the end portion sandwiched between the tenter clips was slit with a laser cutter and wound up to have a thickness of 15 μm and a width of 1500 mm. The base film 1 of the above was prepared.

<Preparation of base film 2 to 11>
In the preparation of the base film 1, the resins (polymers) shown in Table I are used instead of the cycloolefin resin RX4500, and the base films 2 to the same are used so as to have the film thickness shown in Table I. 11 was prepared.

≪Measurement of moisture permeability≫
The moisture permeability of the base film is a value measured by leaving the film to be measured under the conditions of 40 ° C. and 90% RH for 24 hours based on the calcium chloride-cup method described in JIS Z-0208: 1976. ..

As described above, the moisture permeability of the base film was measured in accordance with JIS Z 0208: 1976 after being left in an environment with a temperature of 40 ° C. and a relative humidity of 90% RH for 24 hours.

≪Measurement of humidity dimension change rate≫
The prepared base film is cut into A4 size, two marks (crosses) are attached in the longitudinal direction or the width direction, and the humidity is adjusted for 24 hours in an environment of a temperature of 23 ° C. and a humidity of 20% RH. The distance was measured with an optical microscope. This was designated as L ₁ . Next, the humidity was adjusted for 24 hours in an environment of a temperature of 23 ° C. and a humidity of 80% RH, and the distance between the two points was measured with an optical microscope. This was designated as L ₂ . The dimensional change rate was calculated using the following formula. The measurement was carried out at 10 points on the film surface at random, and the maximum value of the dimensional change rate was adopted.

Dimensional change rate (%) = {(L _2- L ₁ ) / L ₁ } x 100
Table I shows the composition of the resin (polymer) used for the above base film and the measured values of the film thickness, the moisture permeability and the humidity dimensional change rate.

3. 3. Material of functional layer (1) Modified acrylic (Ac): MMA / PMI / HA copolymer (85/10/5 mass ratio), Mw: 2 million, Tg: 122 ° C.
(The above abbreviations represent MMA: methyl methacrylate, PMI: phenylmaleimide, and HA: 2-ethylhexyl acrylate.)
(2) Styrene-maleic anhydride copolymer (St-MA): DYLARK D332 manufactured by NOVA Chemicals, Inc.
(3) Fumaric acid diester (Rn): TYR-HR manufactured by Tosoh Chemical Co., Ltd.
(4) Polyimide (CPI): A weight having a structural unit derived from 4,4'-(hexafluoroisopropyridene) diphthalic anhydride and a structural unit derived from 2,2'-bis (trifluoromethyl) benzidine. Combined, Mw: 150,000, Tg: 350 ° C
(5) TAC: Acetyl cellulose with an acetyl substitution degree of 2.80 (commercially available: manufactured by Wako Pure Chemical Industries, Ltd.)
Table II shows the resin types (abbreviations) and model numbers.

4. Fabrication of laminated film: Formation of functional layer <Preparation of laminated film 1>
The following functional layers were laminated using the prepared base film 1 to prepare a laminated film 1.

<Preparation of rubber particles R1>
The rubber particles R1 prepared by the following method were used.

The following substances were charged into an 8L polymerization device with a stirrer.

Deionized water 180 parts by mass Polyoxyethylene lauryl ether phosphoric acid 0.002 parts by mass Boric acid 0.4725 parts by mass Sodium carbonate 0.04725 parts by mass Sodium hydroxide 0.0076 parts by mass The inside of the polymerization machine was sufficiently replaced with nitrogen gas. After that, the internal temperature was adjusted to 80 ° C., and 0.021 parts by mass of potassium persulfate was added as a 2% aqueous solution. Next, a monomer composed of 84.6% by mass of methyl methacrylate, 5.9% by mass of butyl acrylate, 7.9% by mass of styrene, 0.5% by mass of allyl methacrylate, and 1.1% by mass of n-octyl mercaptan. A mixed solution prepared by adding 0.07 parts by mass of polyoxyethylene lauryl ether phosphoric acid to 21 parts by mass of the mixture (c') was continuously added to the above solution over 63 minutes. Further, by continuing the polymerization reaction for 60 minutes, a hard polymer (c) for a core was obtained.

Then, 0.021 parts by mass of sodium hydroxide was added as a 2% by mass aqueous solution, and 0.062 parts by mass of potassium persulfate was added as a 2% by mass aqueous solution. Next, 0.25 polyoxyethylene lauryl ether phosphate was added to 39 parts by mass of the monomer mixture (a') consisting of 80.0% by mass of butyl acrylate, 18.5% by mass of styrene, and 1.5% by mass of allyl methacrylate. The mixed solution to which the mass part was added was continuously added over 117 minutes. After completion of the addition, 0.012 parts by mass of potassium persulfate was added in a 2% by mass aqueous solution, and the polymerization reaction was continued for 120 minutes to obtain a soft layer (a layer made of an acrylic rubber-like polymer (a)). The glass transition temperature (Tg) of the soft layer was −30 ° C. The glass transition temperature of the soft layer was calculated by averaging the glass transition temperature of the homopolymer of each monomer constituting the acrylic rubber-like polymer (a) according to the composition ratio.

Then, 0.04 parts by mass of potassium persulfate was added in a 2% by mass aqueous solution, and 26.1% by mass of a monomer mixture (b') composed of 97.5% by mass of methyl methacrylate and 2.5% by mass of butyl acrylate was added. The portions were added continuously over 78 minutes. The polymerization reaction was continued for another 30 minutes to obtain a polymer (b).

The obtained polymer was put into a warm aqueous solution of 3% by mass sodium sulfate for salting out and coagulation. Then, after repeating dehydration and washing, the particles were dried to obtain acrylic graft copolymer particles (rubber particles R1) having a three-layer structure. The average particle size of the obtained rubber particles R1 was 200 nm.

The average particle size of the rubber particles was measured by the following method.

(Average particle size)
The dispersed particle size of the rubber particles in the obtained dispersion was measured by a zeta potential / particle size measuring system (ELSZ-2000ZS manufactured by Otsuka Electronics Co., Ltd.).

<Preparation of solution 1 for functional layer>
The following components were mixed to obtain a solution 1 for the functional layer.

Acetone (ketones) 1012.5 parts by mass Methanol (alcohols) 112.5 parts by mass Modified acrylic (Ac) 100 parts by mass Rubber particles R1 25 parts by mass

<Preparation of solutions 2 to 4 for functional layers>
In the functional layer solution 1, the resin (polymer) used was changed from modified acrylic (Ac) to styrene-maleic anhydride copolymer (St-MA), fumaric acid ester (Rn), and polyimide (CPI), respectively. Then, solutions 2 to 4 for the functional layer were prepared with the following compositions.
Acetone (ketones) 1057.5 parts by mass Methanol (alcohols) 67.5 parts by mass Resin composition (St-MA, Rn, CPI) 125 parts by mass

<Preparation of solution 5 for functional layer>
The functional layer solution 5 was similarly prepared with the following composition.
MEK (Methylethylketone) 1057.5 parts by mass Methanol (alcohols) 67.5 parts by mass Sugar ester (octaacetylsucrose) 15 parts by mass Triacetyl cellulose (TAC, acetyl cellulose with acetyl substitution degree 2.80, Mn: 70000) 110 Mass part

<Preparation of laminated film 1 (formation of functional layer)>
As the support, the functional layer solution 1 is applied onto the base film 1 by the backcoat method using a die, and then the drying speed is 0.002 kg / hr · m ² , and the hot air and the functional layer applied from the support side are applied. The temperature of the hot air applied from the side was set to 130 ° C. and dried to form a functional layer having a thickness of 5 μm to obtain a laminated film 1.

<Preparation of laminated films 2 to 19 (formation of functional layer)>
In the preparation of the laminated film 1, the types and layer thicknesses of the base film and the functional layer were changed to the combinations of Tables III and IV, and the laminated films 2 to 19 were prepared.
In the case of a resin composition other than the modified acrylic (Ac), the solution for the functional layer was prepared with the following composition.
Dichloromethane 1057.5 parts by mass Methanol (alcohols) 67.5 parts by mass 125 parts by mass of resin composition of functional layer

≪Evaluation≫
The following evaluations were carried out using the produced laminated films 1 to 19.

<Polarizing plate curl>
<Manufacturing of polarizing plate>
Using the laminated films 1 to 19 prepared above, a polarizing plate was prepared by the following procedure.

(Preparation of polarizer layer)
A long polyvinyl alcohol film with a thickness of 60 μm is continuously conveyed via a guide roller and immersed in a dyeing bath (30 ° C.) containing iodine and potassium iodide for 2.5 times the dyeing treatment. After the stretching treatment, in an acidic bath (60 ° C.) to which boric acid and potassium iodide were added, a total of 5 times the stretching treatment and the cross-linking treatment were performed, and the obtained iodine-PVA system having a thickness of 12 μm was obtained. The polarizer layer was dried in a dryer at 50 ° C. for 30 minutes to obtain a polarizer layer having a moisture content of 4.9%.

(Preparation of polarizing plate)
The above-prepared polarizing element layers are sandwiched from both sides by using the optical films shown in Tables III and IV as opposed films with the laminated films 1 to 19, and are adhered to each other via the following water-soluble adhesive liquid 1 to form a polarizing plate. 101 to 119 were produced. At that time, the longitudinal axis of the polarizer layer and the longitudinal axis of the laminated film were aligned and bonded.

<Opposite film>
As the opposing film, a film containing the following resin was used.
COP (Cycloolefin): ARTON / RX4500 manufactured by JSR Corporation
TAC (Triacetyl Cellulose): Acetyl Cellulose with Degree of Substitution of 2.9 PMMA (Polymethyl Methacrylate): 80N manufactured by Asahi Kasei Corporation
PET (polyethylene terephthalate): Cosmo Shine SRF manufactured by Toyobo Co., Ltd.

(Preparation of water-soluble adhesive liquid 1)
After mixing each of the following components, defoaming was performed to prepare a water-soluble adhesive liquid 1.

100 parts by mass of pure water "Epocross WS-300" manufactured by Nippon Shokubai Co., Ltd. 7.5 parts by mass "CROSSLINKER CL-427" manufactured by Menadione
0.1 part by mass In the production of the polarizing plate, the surface of the laminated film on the adhesive side was subjected to corona discharge treatment at a corona output strength of 2.0 kW and a line speed of 18 m / min, and the water-soluble adhesive prepared above was applied to the corona discharge treated surface. The agent solution 1 was coated with a bar coater so that the film thickness after drying was about 3 μm, and then dried at 50 ° C., 60 ° C., and 70 ° C. in this order for 60 seconds to obtain a polarizing plate.

The obtained polarizing plate was cut into a circle with a diameter of 5 cm and used as a sample. The obtained sample was left for 24 hours in a constant temperature and humidity chamber having a temperature of 23 ° C. and a humidity of 55% RH. Then, the sample was taken out from the constant temperature and humidity chamber, placed on a flat plate, and 1 / r was obtained from the radius of curvature r (m) having a curve matching the sample using a curvature scale. Then, the curl amount was evaluated based on the following criteria.

◯: 1 / r is less than 8 Δ: 1 / r is 8 or more and less than 12 ×: 1 / r is 12 or more and Δ or more, it is judged to be good.

<Polarizing plate adhesiveness>
The peeling strength (adhesiveness) when peeled at the interface between the functional layer laminated on the base film of the obtained polarizing plate and the polarizer layer was 90 ° in an environment of a temperature of 23 ° C. and a humidity of 55% RH. The peel test (based on JIS Z0237: 2009) was measured with a 90 ° peeling test jig (P90-200N) manufactured by Imada Co., Ltd.

◯: Peeling strength is 2.0 (N / 25 mm) or more Δ: Peeling strength is 1.0 (N / 25 mm) or more and less than 2.0 (N / 25 mm) ×: Peeling strength is 1.0 (N / 25 mm) If it is less than Δ or more, it is judged to be good.

<Light leakage>
<Liquid crystal display device>
As a liquid crystal cell, an IPS type liquid crystal cell having a glass substrate having a total thickness of 0.25 mm between two opposing sheets and a liquid crystal layer arranged between them was prepared. Then, after the base film is peeled off from the prepared polarizing plates 101 to 119, the liquid crystal display panels 201 to 219 are attached to both sides of the liquid crystal cell via the adhesive layer so that the functional layer side is the liquid crystal cell side. Obtained. The two polarizing plates were bonded together so that the light transmission axes of the polarizing element layers were in a cross-nicol state.

The liquid crystal display device produced above was displayed in black while the backlight was turned on, and light leakage was evaluated based on the following criteria.

◯: No light leakage is observed or slight light leakage is observed, but there is no problem in actual use. Δ: Light leakage is observed, but the quality is acceptable in actual use. ×: Clear light leakage is observed. There is a problem in actual use. Light leakage is unevenness caused by a decrease in the degree of polarization and a phase difference value (Ro, Rt), and appears as wavy white spots. If it is Δ or more, it is judged to be good.

<Bendmura>
The liquid crystal display device produced above was left to stand in an environment of 40 ° C. and 80% RH for 80 hours. Next, in a state where the liquid crystal display device is displayed in black in a dry environment of 60 ° C., the difference between the brightness near the four vertices of the display screen and the brightness near the center of the display screen (optical unevenness between the center and the periphery). Was visually observed. Then, the bend unevenness was evaluated based on the following evaluation criteria.

◯: No or slight bend unevenness is observed, but there is no problem in actual use. Δ: Bend unevenness is observed, but the quality is acceptable in actual use. ×: Clear bend unevenness is observed, and there is no problem in actual use. There is a problem Bend unevenness is optical unevenness caused by bending deformation of a panel that tends to occur when the polarizing plate curl is strong or the protective film is thick, and it appears as circular unevenness in the center of the screen. If it is Δ or more, it is judged to be good.

The composition of the above laminated film and the evaluation results are shown in Table III and Table IV.

From the evaluation results in Tables III and IV, it is clear that the laminated film of the present invention is excellent in polarizing plate curl, adhesiveness, light leakage of the display device, and optical unevenness due to bend deformation.

Although the laminated film of the present invention is a thin film, it can be handled in the same manner as a conventional polarizing plate protective film, and further has excellent drying property, dimensional stability, and curl controllability during polarizing plate processing. Therefore, the productivity of the polarizing plate processing is improved, and the polarizing plate provided with the polarizing plate can provide a high-quality display device without optical unevenness due to light leakage or bend deformation.

1 Laminated film 2 Base film 3 Functional layer 4 Adhesive layer 5 Polarizer layer 6

Opposed film

10a, 10b Plate plate A1 Melting kettle A2, A5, A11, A14 Liquid transfer pump A3, A6, A12, A15 Filter A4, A13 Stock tank A8, A16 Conduit A10 Additive preparation pot A20 Confluence pipe A21 Mixer A30 Die A31 Metal support A32 Web A33 Peeling position A34 Tenter device A35 Roller drying device A36 Roller A37 Winder A41 Stock tank A43 Pump A44 Rolling device B110 Base film B120 Functional layer B200 Manufacturing device B210 Supply section B220 Coating section B230 Drying section B240 Cooling section B250 Winding section

Claims

A laminated film in which at least a peelable functional layer is laminated on a base film.
The layer thickness of the functional layer is in the range of 1 to 19 μm.
Temperature 40 ° C. of the substrate film, the moisture permeability under humidity of 90% RH is in the range of 100 ~ 400g / m 2 · 24h ,
The maximum dimensional change rate in the film surface in the temperature range of 23 ° C. and the humidity range of 20 to 80% RH of the base film is in the range of 0.01 to 0.10%, and
A laminated film characterized in that the film thickness of the base film is in the range of 20 to 60 μm.
The laminated film according to claim 1, wherein the functional layer has a layer thickness in the range of 2 to 10 μm.
Claim 1 or claim, wherein the base film contains any one of a cycloolefin resin, a polyarylate resin, a styrene / (meth) acrylate copolymer, or a styrene / hydroxystyrene copolymer. Item 2. The laminated film according to Item 2.
A polarizing plate comprising the laminated film according to any one of claims 1 to 3.
A display device comprising the laminated film according to any one of claims 1 to 3 or the polarizing plate according to claim 4.
A method for producing a polarizing plate roll, wherein the laminated film according to any one of claims 1 to 3 is wound while being bonded to at least one surface of a polarizing element layer.
A polarizing plate roll including a step of winding the laminated film while adhering the laminated film to the polarizing layer so that the layers of the polarizer layer, the adhesive layer, the functional layer and the base film are arranged in this order from the inside of the roll. Manufacturing method.