TWI737873B - Manufacturing method of optical film - Google Patents

Abstract

A manufacturing method of an optical film, a polarizing plate and a display device using the optical film. The manufacturing method of the aforementioned optical film includes a peeling step from providing a multilayer film to a peeling treatment. The multilayer film includes a film (A) made of a thermoplastic resin A and a film provided on one or both sides of the film (A) ( B) For the multilayer film, the peeling treatment includes peeling the film (B) from the film (A) by applying force along the thickness direction of the film (A) at the temperature Tov (°C), and the temperature Tov is the same as the foregoing The glass transition temperature TgA(℃) of the film (A) satisfies the relationship of Tov≧TgA. In the aforementioned multilayer film, the peeling force Pa of the aforementioned film (A) and the aforementioned film (B) at the temperature Tov is 0.03N/50mm or more And 0.5N/50mm or less.

Description

Manufacturing method of optical film

The present invention relates to a manufacturing method of an optical film, a polarizing plate and a display device.

In display devices such as liquid crystal display devices, for the purpose of optical compensation, etc., the installation of resin-made optical films with phase difference is now widely carried out. As a method of imparting a phase difference to a resin film, the stretching of this film is currently being widely carried out.

As such an optical film, there is a case where a film whose NZ coefficient Nz satisfies 0<Nz<1 is sought, and a film with 0.4<Nz<1 is preferred, and a film with Nz=0.5 is more ideal. However, when the film is stretched by the usual method, since the value of the NZ coefficient becomes a value less than 0 or a value greater than 1, it is difficult to obtain a film with 0<Nz<1.

As a method to obtain a film with 0<Nz<1, a multilayer film combining multiple films can be considered. However, a simpler single-layer structure is now being sought to achieve a film with 0<Nz<1.

As a method for realizing a film of 0<Nz<1 with a single-layer film, the method described in Patent Document 1 (Japanese Patent Publication No. H08-207119 (corresponding to other countries: European Patent Application Publication No. 0707938)) is known . In Patent Document 1, a shrink film is attached to a resin film to be processed, and then the shrink film is shrunk to shrink the resin film. As a result, 0<Nz<1 is achieved.

However, in the method described in Patent Document 1, it is difficult to control the shrinkage force of the shrink film, and the steps for shrinking the shrink film are complicated, and it is difficult to easily produce a film of 0<Nz<1.

Therefore, the object of the present invention is to provide an optical film manufacturing method that can easily manufacture an optical film of 0<Nz<1. A further object of the present invention is to provide a polarizing plate that can be easily manufactured and has a high degree of optical compensation, and to provide a display device that can be easily manufactured and exhibits a high degree of optical compensation.

The inventors of the present invention conducted studies in order to solve the aforementioned problems. As a result, the inventors of the present invention found that as an unprecedented manufacturing method of optical films, this problem can be solved by stretching the film in the thickness direction by utilizing the peeling force of the film. Furthermore, it was found that by setting the temperature for stretching in the thickness direction to a specific temperature and the characteristics of the multilayer film to be peeled off as specific characteristics, a good thickness direction stretching operation can be performed. The present invention was completed based on this discovery.

That is, the present invention is as follows.

[1] A method of manufacturing an optical film, including a peeling step of providing a multilayer film in a peeling process; the multilayer film includes a film (A) made of a thermoplastic resin A and disposed on one or both sides of the film (A) A multilayer film of the film (B) on the side; the peeling treatment includes peeling the film (B) from the film (A) by applying a force along the thickness direction of the film (A) at the temperature Tov (℃); The temperature Tov and the glass transition temperature TgA (℃) of the aforementioned film (A) satisfy the relationship Tov≧TgA; in the aforementioned multilayer film, the peeling force Pa of the aforementioned film (A) and the aforementioned film (B) at the temperature Tov is 0.03 N/50mm or more and 0.5 N/50mm or less.

[2] The method for producing an optical film as described in [1], wherein the thermoplastic resin A contains an alicyclic structure-containing polymer.

[3] The method for manufacturing an optical film as described in [1] or [2], further comprising a stretching step of extending the multilayer film in the in-plane direction of the multilayer film.

[4] A polarizing plate provided with an optical film and a polarizing member manufactured by the manufacturing method described in any one of [1] to [3].

[5] A display device including an optical film manufactured by the manufacturing method described in any one of [1] to [3].

According to the present invention, there is provided a method for manufacturing an optical film that can easily manufacture an optical film with 0<Nz<1; a polarizing plate that can be easily manufactured and has a high degree of optical compensation; and a display device that can be easily manufactured and exhibits a high degree of optical compensation .

Hereinafter, the implementation modes and examples of the present invention will be described in detail. However, the present invention is not limited to the embodiments and exemplified materials disclosed below, and can be arbitrarily changed and implemented without departing from the scope of the present invention and its equivalent scope.

In the following description, unless otherwise noted, the in-plane retardation Re of the film is the value represented by Re=(nx−ny)×d. Unless otherwise noted, the retardation Rth in the thickness direction of the film is The value represented by Rth={(nx+ny)/2−nz}×d. Moreover, the NZ coefficient Nz of the film is a value represented by Nz=(nx−nz)/(nx−ny), which can also be represented by Nz=(Rth/Re)+0.5. Here, nx represents the in-plane direction of the film, that is, the refractive index in the direction perpendicular to the thickness direction of the film that gives the maximum refractive index. ny represents the refractive index in the direction orthogonal to the nx direction in the aforementioned in-plane direction. nz represents the refractive index in the thickness direction. d represents the thickness of the film. Unless otherwise noted, the measurement wavelength of the in-plane retardation is 590 nm.

In the following description, unless otherwise noted, the so-called "polarizing plate" is not only a rigid component, but also a flexible component such as a resin film.

In the following description, the so-called "long strip" film refers to a film having a length of 5 times or more relative to the width, preferably a length of 10 times or more, and specifically refers to a film that is wound into a roll shape. The length of the film for storage or transportation. The upper limit of the length of the long film is not particularly limited, and may be, for example, 100,000 times or less relative to the width of the film.

In this technical field, the so-called "stretching" of the film generally means the operation of deforming the film by expanding the shape of the film in more than one direction of the in-plane direction of the film. However, in this application, the "extension" of the film is not limited to this, but also includes expanding the shape of the film in directions other than the in-plane direction (directions that are not parallel to the surface direction of the film, such as the thickness direction, etc.). Deformation operation. In the following description, when the context is clear, the operation of deforming the film by expanding the shape of the film in more than one direction of the in-plane direction of the film is generally referred to as "stretching". On the other hand, it is different from the usual "stretching", and the process of deforming the film by expanding the shape of the film in a direction other than the in-plane direction is called "thickness-direction stretching", and the film that has been processed in this way It is called "thickness-direction stretched film".

[1. Manufacturing method of optical film]

The manufacturing method of the optical film of the present invention includes a peeling step of providing a specific multilayer film in a specific peeling treatment.

[1.1. Multilayer film]

The multilayer film provided in the peeling step includes a film (A) made of a thermoplastic resin A and a film (B) provided on one or both sides of the aforementioned film (A).

[1.1.1. Film (A)]

The thermoplastic resin A constituting the film (A) is not particularly limited, and the desired physical properties as an optical film may be imparted, and resins containing various polymers may be appropriately selected and used.

As a preferable example of the polymer contained in the thermoplastic resin A, an alicyclic structure-containing polymer can be cited.

The alicyclic structure-containing polymer is a polymer having an alicyclic structure in the repeating unit, and any one of a polymer containing an alicyclic structure in the main chain and a polymer containing an alicyclic structure in the side chain can be used. The alicyclic structure-containing polymer may include crystalline resin and amorphous polymer. From the viewpoint of obtaining the desired effect of the present invention and the viewpoint of production cost, an amorphous alicyclic structure-containing polymer is preferred.

Examples of the alicyclic structure possessed by the amorphous alicyclic structure-containing polymer include a cycloalkane structure and a cycloalkene structure, but from the viewpoint of thermal stability and the like, a cycloalkane structure is preferred.

The number of carbons in the repeating unit constituting an alicyclic structure is not particularly limited, but is usually 4 to 30, preferably 5 to 20, and more preferably 6 to 15.

The proportion of the alicyclic structure-containing repeating unit in the alicyclic structure-containing polymer may be appropriately selected depending on the purpose of use, but is usually 50% by weight or more, preferably 70% by weight or more, and more preferably 90% by weight or more. Setting the repeating unit with alicyclic structure to such a large number can improve the heat resistance of the base film.

Specific examples of the alicyclic structure-containing polymer include: (1) norbornene polymer, (2) monocyclic cycloolefin polymer, (3) cyclic conjugated diene polymer, (4) Vinyl alicyclic hydrocarbon polymers, and these hydrides, etc. Among them, from the viewpoints of transparency and moldability, norene polymers and their hydrogenated products are preferred.

Examples of norrene polymers include: ring-opening polymers of norrene monomers, ring-opening copolymers formed with other monomers capable of ring-opening copolymerization with norrene monomers, and hydrogenated products of these ;Norene monomer addition polymer, addition copolymer formed with other monomers that can be copolymerized with norene monomer, etc. Among them, from the viewpoint of transparency, hydrogenated products of ring-opening polymers of norene monomers are particularly preferred.

As an example of the aforementioned alicyclic structure-containing polymer, for example, the polymer disclosed in Japanese Patent Publication No. 2002-321302 can be cited.

Furthermore, as an example of a crystalline alicyclic structure-containing polymer, the polymer disclosed in Japanese Patent Publication No. 2016-26909 can be cited.

As other examples of polymers included in the thermoplastic resin A, widely used polymers such as triacetyl cellulose and polystyrene polymers can be cited. In particular, among polystyrene polymers, it is particularly preferable to use a polystyrene polymer having a syndiotactic structure. As an example of a polystyrene-based polymer having a parallel structure, a polymer disclosed in Japanese Patent Publication No. 2014-186273 can be cited.

The weight average molecular weight of the polymer contained in the thermoplastic resin A is not particularly limited, but is preferably 10,000 or more, more preferably 20,000 or more, more preferably 300,000 or less, and more preferably 250,000 or less. When the weight average molecular weight is within this range, thermoplastic resin A with excellent mechanical strength and moldability can be easily obtained.

Although the thermoplastic resin A may be composed only of a polymer containing the above-mentioned substances as a main component, it may contain any admixture as long as the effect of the present invention is not significantly impaired. In the resin, the ratio of the polymer as the main component is preferably 70% by weight or more, and more preferably 80% by weight or more.

Among various commercially available products, the thermoplastic resin A should be appropriately selected and used as the thermoplastic resin A having the desired characteristics. As an example of this commercially available product, the product name "ZEONOR" (manufactured by Zeon Corporation), the product name "TOPAS" (manufactured by POLYPLASTICS Co., Ltd.), and the product name "ARTON" (manufactured by JSR Co., Ltd.) ) Of the product group.

The glass transition temperature TgA of the thermoplastic resin A is preferably 100°C or higher, preferably 110°C or higher, further preferably 180°C or lower, and preferably 170°C or lower. When TgA is in this range, processing such as stretching in the thickness direction can be smoothly performed, and an optical film with desired optical properties can be easily obtained.

The thickness of the film (A) is preferably 10 μm or more, more preferably 20 μm or more, more preferably 200 μm or less, and more preferably 190 μm or less. When the thickness of the film (A) is within this range, processing such as stretching in the thickness direction can be smoothly performed, and an optical film with desired optical properties can be easily obtained.

The method of manufacturing the film (A) is not particularly limited, and any manufacturing method may be adopted. For example, by molding the thermoplastic resin A into a desired shape, a film (A) can be produced. As a good example of the molding method for molding the resin A, extrusion molding can be cited. By performing extrusion molding, the film (A) with the desired size can be manufactured efficiently.

[1.1.2. Film (B)]

The material constituting the film (B) is not particularly limited, and a resin containing various polymers suitable for the implementation of the present invention can be appropriately selected and used. In the following, this resin is referred to as "Resin B" for short.

As the resin B, a thermoplastic resin must be used. As an example of the polymer contained in the resin B and the preferable range of its molecular weight, the same examples as the examples of the alicyclic structure-containing polymer contained in the thermoplastic resin A and other polymers listed above can be cited.

As another example of the alicyclic structure-containing polymer contained in the resin B, there may be mentioned: a polymer block containing two or more hydride units of a cyclic hydrocarbon group-containing compound [I] and a hydride unit of a chain hydrocarbon compound [II] ] Or a combination of unit [I] and unit [II], a hydrogenated block copolymer of one or more polymer blocks. As a specific example of this hydrogenated block copolymer, for example, the polymer disclosed in International Patent Publication No. WO2016/152871 can be cited.

As other examples of polymers contained in resin B, widely used polymers such as polypropylene, (meth)acrylate polymers, and polyimides can be cited. Among commercially available products, resin B should be appropriately selected and used with desired characteristics. As an example of this commercially available product, a self-adhesive stretched polypropylene film (for example, manufactured by Futamura Chemical Co., Ltd., trade name "FSA 010M #30") can be cited.

The thickness of the film (B) is preferably 10 μm or more, preferably 15 μm or more, more preferably 100 μm or less, and more preferably 90 μm or less. When the thickness of the film (B) is within this range, processing such as stretching in the thickness direction can be smoothly performed, and an optical film with desired optical properties can be easily obtained.

The method of manufacturing the film (B) is not particularly limited, and any manufacturing method may be adopted. For example, by molding the resin B into a desired shape, a film (B) can be produced. As a good example of the molding method for molding the resin B, extrusion molding can be cited. By performing extrusion molding, the film (B) with the desired size can be efficiently manufactured.

[1.1.3. Other layers]

In addition to the film (A) and the film (B), the multilayer film must contain any layer. For example, an adhesive layer must be included. As the adhesive constituting the adhesive layer, various commercially available adhesives can be used. Specifically, it is necessary to use an adhesive containing an acrylic polymer as a polymer as the main component. For example, a commercially available film with an adhesive layer (such as "MASTACK series" manufactured by Fujimori Kogyo) transfers the adhesive layer to the film (A) or film (B), and this can be used as a multi-layer film. Adhesive layer.

In the case of a multilayer film with an adhesive layer between the films (A) and (B), it is better that the adhesive layer's adhesion to the film (B) is higher than its adhesion to the film (A). By having such a difference in adhesion, the residual glue for the optical film can be reduced, and high-quality optical film can be easily obtained. This difference in adhesion can be obtained by appropriately selecting the material of the adhesive layer or applying appropriate surface treatment on the surfaces of the films (A) and (B) as required.

[1.1.4. Peeling force]

In the manufacturing method of the present invention, the film (A) and the film (B) used at the temperature Tov whose peeling force Pa is within a specific range is used as a multilayer film. Here, the temperature Tov is the film temperature in the peeling step of the manufacturing method of the present invention.

The peeling force Pa is 0.03 N/50mm or more, preferably 0.035 N/50mm or more, preferably 0.04 N/50mm or more, and 0.5 N/50mm or less, preferably 0.4 N/50mm or less, preferably 0.3 N/ It is preferably 50 mm or less. When the peeling force is within this range, the generation of wrinkles in the step of the peeling step can be suppressed, and the unintentional peeling of the film (B) at the stage before the peeling step can be suppressed, and it can be achieved in the film (A). The surface peels well, and the optical film of good quality can be manufactured smoothly.

The peeling force Pa can be obtained by performing a 180º peeling test on the multilayer film. In the 180º peel test, the multi-layer film must be cut into slices in the longitudinal direction × width direction = 300 mm × 50 mm, and placed in a tensile testing machine with a constant temperature and humidity chamber (for example, "5564" manufactured by INSTRON) , Implemented at the temperature Tov. Specifically, the film (A) is held by the chuck on one side of the measuring device, and the film (B) is held by the chuck on the other side, and the drawing speed is 300 mm/min. Have to implement a peel test.

[1.1.5. Preparation method of multilayer film]

The method for preparing the multilayer film provided in the manufacturing method of the present invention is not particularly limited, and any method may be adopted. This preparation is performed, for example, by bonding the film (A) and the film (B). Before lamination, the film (A) and/or film (B) may be subjected to surface treatment such as corona treatment as required. Furthermore, before lamination, an adhesive layer may be formed on the surface of the film (A) and/or the film (B) as required, and the adhesive layer may be used for lamination. The long film (A) and the long film (B) have to be laminated by aligning the longitudinal direction and laminating the long film (A) and the long film (B) by roll-to-roll.

[1.2. Peeling steps]

In the peeling step in the manufacturing method of the present invention, the multilayer film is provided for peeling treatment. The peeling treatment includes the action of peeling the film (B) from the film (A). By performing this peeling treatment, traction can be applied to the film (A) in the thickness direction, and as a result, the film (A) can be stretched in the thickness direction. In the case of the multi-layer film (B), the multi-layer film (B) is usually peeled off at the same time.

FIG. 1 is a side view schematically showing an example of the peeling device for performing the peeling step in the manufacturing method of the present invention and the operation of the peeling step using the device. In FIG. 1, the long multi-layer film 100 is transported in the direction of the arrow A11, and then provided in the peeling area P for the peeling step.

The multilayer film 100 includes a film (A) 131, a film (B) 111 disposed on one side of the film (A) 131, and a film (B) 112 disposed on the other side of the film (A) 131. The multilayer film 100 further includes adhesive layers 121 and 122 between the films (A) and (B). The thickness of the film (A) 131 in the multilayer film is indicated by the arrow A14.

The peeling treatment in the peeling step can be performed by pulling the film (B) in a direction different from the in-plane direction of the transported film (A). In the example of FIG. 1, the film (B) 111 is drawn along the longitudinal direction of the film (B) 111 to arrow A12 in the peeling area P, and the film (B) 112 is drawn along the longitudinal direction of the film (B) 112 to arrow A12. No. A13. Thereby, peeling is performed from downstream to upstream in the conveying direction of the multilayer film, and the films (B) 111 and 112 can be peeled off by applying force in the thickness direction of the film (A) 131. The so-called force in the thickness direction of the film is a force in a direction that is not parallel to the in-plane direction of the film, preferably a direction close to the direction perpendicular to the surface of the film. As a result of such a peeling step, an optical film 132 extending in the thickness direction can be obtained. Moreover, by balancing the traction force in the direction of the arrow A12 and the traction force in the direction of the arrow A13, such traction can be performed without imparting undesirable in-plane tension to the multilayer film 100 and the optical film 132.

In the example of FIG. 1, the thickness of the optical film 132 is indicated by an arrow A15. As a result of the extension in the thickness direction, the optical film 132 has a thicker thickness than the film (A) 131 in the multilayer film 100. However, the manufacturing method of the present invention is not limited to this. For example, the peeling step is accompanied by the extension in the in-plane direction. Although the thickness of the optical film is not necessarily thicker than the thickness of the film (A), even in this case, it is possible to obtain 0<Nz<1 The situation of the optical film.

The optical film 132 obtained as a result of the peeling step in the peeling area P is further transported along the arrow A11. The multilayer film 100 and the optical film 132 are conveyed in a state of being held by the rollers 151 and 152 at the upstream of the peeling area and the rollers 161 and 162 at the downstream of the peeling area. The conveying speed can be adjusted by appropriately adjusting the circumferential velocity of these rolls.

Moreover, the peripheral speed of the downstream rolls may be adjusted to be faster than the peripheral speed of the upstream rolls according to demand. By performing this adjustment, desired tension can be imparted to the multilayer film 100 and the optical film 132. If necessary, the stretching step along the longitudinal direction of the film can be performed along with the peeling step by adjusting the tension. Furthermore, depending on the needs, it can also be extended in any direction in the film surface at the same time as the peeling step, or in the upstream or downstream of the peeling area P.

In the manufacturing method of the optical film of the present invention, the stretching magnification in the case of stretching in the in-plane direction in addition to the thickness direction stretching can be appropriately adjusted in accordance with the desired optical performance desired to be imparted to the optical film. The specific stretching ratio is preferably 1 time or more, preferably 1.01 times or more, further preferably 2 times or less, and more preferably 1.8 times or less. When the stretching magnification in the in-plane direction is in this range, the desired optical performance can be easily obtained.

In the peeling device, when the peeling step of the long multi-layer film is continuously performed, the peeling area P can be set at a certain position in the peeling device by balancing the transport speed and the peeling speed of the multilayer film. In this case, the transport speed of the multilayer film becomes the peeling speed. The peeling speed should be adjusted appropriately in accordance with the desired optical properties that are desired to be imparted to the optical film. The specific peeling speed is preferably 1 m/min or more, preferably 2 m/min or more, more preferably 50 m/min or less, and preferably 40 m/min or less. When the peeling speed is within this range, the desired optical performance can be easily obtained.

In the manufacturing method of the optical film of the present invention, the peeling step is performed at the temperature Tov (°C). The temperature Tov and the glass transition temperature TgA (℃) of the film (A) satisfy the relationship Tov≧TgA. Tov is preferably (TgA+3)°C or higher, preferably (TgA+5)°C or higher. By adjusting the Tov in this range, the optical film can be easily given the desired NZ coefficient and other optical properties. The upper limit of Tov is not particularly limited, but may be set to (TgA+40)°C or lower, for example. The temperature Tov in the peeling step is in the peeling device. By heating with a suitable heating device, the temperature in the oven (not shown) surrounding the area containing the peeling area can be adjusted.

2 is a side view schematically showing another example of the peeling device for performing the peeling step in the manufacturing method of the present invention and another example of the operation of the peeling step using the device. In FIG. 2, the long multi-layer film 200 is transported along the arrow A21 direction, and then provided in the peeling area P for the peeling step. Although the multilayer film 200 includes the film (A) 231 and the film (B) 211 provided on one side of the film (A) 231, the film (B) is not provided on the other side of the film (A) 231. The multilayer film 200 further includes an adhesive layer 221 between the films (A) and (B). The thickness of the film (A) 231 in the multilayer film is indicated by the arrow A24.

In this example, since the multilayer film 200 only has the film (B) 211 on one side, the peeling process in the peeling step is performed in a direction different from the in-plane direction of the transported film (A). Pull this film (B) 211 in the direction of arrow A22. Therefore, by the rollers 151 and 152 at the upstream of the peeling zone and the rollers 161 and 162 at the downstream of the peeling zone, tension is applied to the multilayer film 200 and the optical film 232 after the peeling step, and this tension resists the pulling of the film (B) 211 . As a result of the peeling step, the film (A) 231 can be extended in the thickness direction to obtain the optical film 232. The optical film 232 has a thickness that is thicker than the film (A) 231 and is indicated by an arrow A25.

[2. Optical film]

According to the manufacturing method of the present invention, an optical film whose NZ coefficient Nz is 0<Nz<1 can be easily manufactured. Nz is preferably 0.4<Nz<1, ideally Nz=0.5. The optical film with this NZ coefficient is difficult to be manufactured by stretching the film in the usual in-plane direction, but it can be effectively used for the purpose of optical compensation of display devices. Therefore, the manufacturing method of the present invention exerts a high effect from the viewpoint of easily manufacturing products that are difficult to manufacture and effective.

The in-plane retardation Re of the optical film is preferably 100 nm or more, more preferably 120 nm or more, more preferably 350 nm or less, and more preferably 300 nm or less. When Re is in this range, an optical film that can be effectively used for optical compensation and other purposes can be constructed. The thickness direction retardation Rth of the optical film is preferably −80 nm or more, preferably −70 nm or more, further preferably 80 nm or less, and preferably 70 nm or less. In the case where Rth is in this range, an optical film that has desired characteristics such as NZ coefficient and is effectively used for applications such as optical compensation can be formed.

[3. Use of optical film: polarizing plate and display device]

The optical film obtained by the manufacturing method of the present invention can be used as a constituent element of an optical device such as a display device. For example, an optical film and other components are combined to form an optical component such as a polarizing plate.

The polarizing plate of the present invention is provided with the optical film and the polarizing member manufactured by the aforementioned manufacturing method of the present invention. The polarizing plate of the present invention can be manufactured by bonding an optical film and a polarizer.

Before bonding to the polarizer, an arbitrary layer can be set on the surface of the optical film. Examples of any layer include: hard coat layer for improving the surface hardness of the film, matte layer for optimizing the smoothness of the film, and anti-reflection layer.

The polarizing plate of the present invention can also be further provided with a bonding agent layer between the film cut from the optical film and the polarizer and used for bonding these.

The polarizer is not particularly limited, and any polarizer may be used. As an example of a polarizer, a polyvinyl alcohol film adsorbs iodine, dichroic dyes, and other materials and then stretches it. Examples of the bonding agent constituting the bonding agent layer include those using various polymers as the base polymer. As an example of this base polymer, for example, acrylic polymer, silicone polymer, polyester, polyurethane, polyether, and synthetic rubber can be cited.

The polarizing plate must have a protective film. Although the number of polarizers and protective films provided in the polarizer is arbitrary, the polarizer of the present invention usually has one layer of polarizer and two protective films provided on both sides of the polarizer. In the two-layer protective film, both of them may be the film cut from the optical film of the present invention, or only one of them may be the film cut from the optical film of the present invention.

The display device of the present invention may include the optical film manufactured by the aforementioned manufacturing method of the present invention. The display device of the present invention preferably has the aforementioned polarizing plate of the present invention. The display device of the present invention can be appropriately constructed by combining the optical film of the present invention with other constituent elements of the display device.

The display device of the present invention is preferably a liquid crystal display device. Examples of liquid crystal display devices include in-plane switching (In-Plane Switching, IPS) mode, vertical alignment (Vertical Alignment, VA) mode, multi-domain vertical alignment (Multi-domain Vertical Alignment, MVA) mode, and continuous pinwheel. Alignment (Continuous Pinwheel Alignment, CPA) mode, Hybrid Alignment Nematic (HAN) mode, Twisted Nematic (TN) mode, Super-Twisted Nematic (STN) mode, optical compensation A liquid crystal display device with a liquid crystal cell driven by a bending (Optical Compensated Bend, OCB) mode.

When the display device of the present invention is a liquid crystal display device, the polarizing plate must be provided as a layer that only allows the specific polarized light to pass through from the light incident on the liquid crystal cell and the light emitted from the liquid crystal cell. The polarizing plate must also be provided as a part of the constituent elements to prevent the reflection of external light.

The display device of the present invention can also be an organic electroluminescence display device. In this case, the aforementioned polarizing plate of the present invention can be provided as a part of the constituent elements for preventing reflection of external light, for example.

Hereinafter, embodiments will be disclosed and the present invention will be specifically described. However, the present invention is not limited to the embodiments disclosed below, and can be implemented with any changes within the scope of the patent application and the equivalent scope of the present invention.

In the following description, unless otherwise noted, the "%" and "parts" of the weight are based on weight. Moreover, unless otherwise noted, the operations described below are performed under normal temperature and pressure conditions.

[Evaluation method]

(Measurement method of glass transition temperature of resin)

Prepare the resin pellet to be measured, and measure the glass transition temperature of the resin pellet using a differential scanning thermal analyzer ("DSC6220" manufactured by SEIKO INSTRUMENTS). The conditions are set as a sample weight of 10 mg, and the heating rate is set at 20°C/min.

(Measurement method of phase difference and NZ coefficient)

Re and Rth were measured using a phase difference measuring device (manufactured by Axometric Corporation, product name "Axoscan") at a wavelength of 590 nm, and the NZ coefficient was obtained based on these.

(Measurement method of peeling force Pa between film (A) and film (B))

Cut out the long multi-layer film of the measuring object, and obtain the slice of longitudinal direction×width direction=300 mm×50 mm. Place the slices in a tensile testing machine (model "5564" manufactured by INSTRON) with a constant temperature and humidity tank, and heat up to the specified oven temperature Tov. Perform a 180º peel test while maintaining the temperature. The 180º peel test is performed with the chuck on one side of the measuring device holding the film (A) and the other side of the chuck holding the film (B), and the stretching speed is 300 mm/min. The average value of the measured value of the peeling force Pa (N/50mm) in the stable stretching distance of 50 mm is used as the value of the peeling force Pa.

[Manufacturing Example 1. Film (A)-1 Manufacturing]

The pellets containing alicyclic structure polymer resin (glass transition temperature of 126°C lower ene polymer resin, trade name "ZEONOR", manufactured by Zeon Co., Ltd.) were dried at 100°C for 5 hours. After that, the dried resin pellets are supplied to a uniaxial extruder. After the resin is melted in the extruder, it is extruded from the T-die on the casting drum through the polymer pipeline and polymer filter into a sheet, and then cooled. In this way, a strip-shaped film (A)-1 with a thickness of 80 μm and a width of 1000 mm was obtained. The produced film (A)-1 is wound into a roll for recovery.

[Manufacturing Example 2. Film (A)-2 Manufacturing]

Change the opening size of the mouth of the T-shaped mold, and perform the same operations as in Manufacturing Example 1. In this way, a long film (A)-2 with a thickness of 185 μm and a width of 1000 mm is obtained, which is wound into a roll for recovery.

[Manufacturing Example 3. Film (A)-3 Manufacturing]

Change the opening size of the mouth of the T-shaped mold, and perform the same operations as in Manufacturing Example 1. By this, a long film (A)-3 with a thickness of 133 μm and a width of 1000 mm is obtained, which is wound into a roll for recovery.

[Manufacturing Example 4. Film (A)-4 Manufacturing]

The film (A)-1 obtained in Production Example 1 was unrolled from a roll, and corona treatment was performed on both sides of the film (A)-1. Thus, film (A)-4 is obtained. The obtained film (A)-4 is wound into a roll for recovery.

[Manufacturing Example 5. Manufacturing of raw film for film (B)]

The pellets of polyester resin ("PET-G 6763" manufactured by EASTMAN) were dried at 120°C for 5 hours. The dried pellets are supplied to the extruder. After it is melted in the extruder, it passes through the polymer pipeline and polymer filter at the resin temperature of 260°C, extrudes it from the T-mold on the casting drum into a sheet, and then cools it. In this way, a raw film with a thickness of 60 μm and a width of 1400 mm was obtained.

[Manufacturing Example 6. Film (B)-1 Manufacturing]

The raw film obtained in Production Example 5 was continuously supplied to the tenter-type lateral stretching device. Use this transverse stretcher to stretch the raw film in the width direction under the conditions of a stretching temperature of 80°C and a stretching ratio of 2 times. The two ends in the width direction of the stretched film are trimmed, and corona treatment is further applied to one side of the film. Thus, a long film (B)-1 with a width of 900 mm and a thickness of 42 μm is obtained. The corona treated surface is wound on the inside, and this film (B)-1 is wound into a roll for recovery.

[Manufacturing example 7. Multilayer film (C)-1 manufacturing]

The film (B)-1 obtained in Production Example 6 was unrolled from the roll, and the adhesive layer (the adhesive layer of "MASTACK series" manufactured by Fujimori Kogyo Co., Ltd.) was transferred to the film (B)-1 after corona treatment Of the face. Next, the film (B)-1 was bonded to both sides of the film (A)-1 obtained in Manufacturing Example 1 in an ordinary method, and the adhesive layer was interposed between the film (B)-1 and the film (A). )-1. By this, a long strip with a layer structure of (film (B)-1)/(adhesive layer)/(film (A)-1)/(adhesive layer)/(film (B)-1) is obtained Multilayer film (C)-1. This multilayer film (C)-1 is wound into a roll for recovery. The thickness of each layer is 42 μm/25 μm/80 μm/25 μm/42 μm.

[Manufacturing example 8. Multilayer film (C)-2 manufacturing]

The film (B)-1 obtained in Production Example 6 was unrolled from the roll, and the adhesive layer (the adhesive layer of "MASTACK series" manufactured by Fujimori Kogyo Co., Ltd.) was transferred to the film (B)-1 after corona treatment Of the face. Next, the film (B)-1 was bonded to both sides of the film (A)-4 obtained in Manufacturing Example 4 in an ordinary method, and the adhesive layer was interposed between the film (B)-1 and the film (A). )-4. By this, a long strip with a layer structure of (film (B)-1)/(adhesive layer)/(film (A)-4)/(adhesive layer)/(film (B)-1) is obtained Multilayer film (C)-2. This multilayer film (C)-2 is wound into a roll for recovery. The thickness of each layer is 42 μm/25 μm/80 μm/25 μm/42 μm.

[Manufacturing Example 9. Manufacturing of Multilayer Film (C)-3]

Prepare a self-adhesive stretched polypropylene film ("FSA 010M #30" manufactured by FUTAMURA Chemical Co., Ltd.) as the film (B)-2. The film (B)-2 was bonded to both sides of the film (A)-1 obtained in Production Example 1 in an ordinary method. Thereby, a long multi-layer film (C)-3 having a layer structure of (film (B)-2)/(film (A)-1)/(film (B)-2) is obtained. This multilayer film (C)-3 is wound into a roll for recovery. The thickness of each layer is 30 μm/80 μm/30 μm.

[Manufacturing example 10. Multi-layer film (C)-4 manufacturing]

The film (A)-2 obtained in Manufacturing Example 2 was used instead of Film (A)-1, and the same operation as in Manufacturing Example 9 was used to obtain (film (B)-2)/(film (A)- 2)/(Film (B)-2) Long strip multilayer film (C)-4 with layer structure. This multilayer film (C)-4 is wound into a roll for recovery. The thickness of each layer is 30 μm/185 μm/30 μm.

[Manufacturing Example 11. Manufacturing of Multilayer Film (C)-5]

The film (A)-3 obtained in Manufacturing Example 3 was used instead of Film (A)-1, and the same operation as in Manufacturing Example 9 was used to obtain (film (B)-2)/(film (A)- 3)/(Film (B)-2) Long-strip multilayer film (C)-5 with layer structure. This multilayer film (C)-5 is wound into a roll for recovery. The thickness of each layer is 30 μm/133 μm/30 μm.

[Manufacturing example 12. Multilayer film (C)-6 manufacturing]

The film (B)-1 obtained in Production Example 6 was unrolled from the roll, and the adhesive layer (the adhesive layer of "MASTACK series" manufactured by Fujimori Kogyo Co., Ltd.) was transferred to the film (B)-1 after corona treatment Of the face. Then, corona treatment is applied to the surface of the transferred adhesive layer. The film (B)-1 with the corona-treated adhesive layer was attached to both sides of the film (A)-4 obtained in Production Example 4 through the adhesive layer in an ordinary method. By this, a long strip with a layer structure of (film (B)-1)/(adhesive layer)/(film (A)-4)/(adhesive layer)/(film (B)-1) is obtained Multilayer film (C)-6. This multilayer film (C)-6 is wound into a roll for recovery. The thickness of each layer is 42 μm/25 μm/80 μm/25 μm/42 μm.

[Example 1]

Prepare floating longitudinal stretcher. This stretching machine is a stretching machine that stretches the conveyed long strip film in the temperature-adjusted oven along its longitudinal direction. The multilayer film (C)-2 obtained in Manufacturing Example 8 was unrolled from a roll, transported in the film longitudinal direction, and supplied to the aforementioned longitudinal stretching machine. Transport the multilayer film (C)-2 to the oven of the longitudinal stretching machine. During transportation, the temperature Tov in the oven was set to 135°C and the stretching ratio was 1.07 times for stretching.

Next, the peeling step is performed near the exit in the oven. The peeling step is performed by pulling the film (B)-1 on both sides of the multilayer film (C)-2 and continuously peeling the film (B)-1 from the film (A)-4. The direction of pulling the two films (B)-1 is the direction perpendicular to the surface of the film (A)-4 being conveyed, and the directions are opposite to each other. Thereby, peeling by applying a force in the thickness direction of the film (A)-4 is performed to extend the film (A)-4 in the thickness direction. The peeling speed is 5 m/min. As a result, a film (A)-4 stretched in the thickness direction was obtained as an optical film.

Measure the in-plane retardation Re, thickness and NZ coefficient of the obtained optical film. Furthermore, the peeling force Pa between the film (A) and the film (B) in the Tov multilayer film of this embodiment was measured. The results are shown in Table 1. From the results in Table 1, it can be seen that the NZ coefficient of the obtained optical film is between 0 and 1.

[Example 2]

The multilayer film (C)-3 obtained in Manufacturing Example 9 was unwound from a roll, transported in the film longitudinal direction, and supplied to the same longitudinal stretching machine as used in Example 1. Transport the multilayer film (C)-3 to the oven of the longitudinal stretching machine. During transportation, the temperature Tov in the oven was set to 126°C. In addition, the stretching ratio was set to 1.00, that is, transportation without stretching was performed.

Next, the peeling step is performed near the exit in the oven. The peeling step is performed by pulling the film (B)-2 on both sides of the multilayer film (C)-3 and continuously peeling the film (B)-2 from the film (A)-1. The direction of pulling the two films (B)-2 is the direction perpendicular to the surface of the film (A)-1 being conveyed, and the directions are opposite to each other. Thereby, peeling with a force applied in the thickness direction of the film (A)-1 is performed to extend the film (A)-1 in the thickness direction. The peeling speed is 1 m/min. As a result, a film (A)-1 stretched in the thickness direction was obtained as an optical film.

Measure the in-plane retardation Re, thickness and NZ coefficient of the obtained optical film. Furthermore, the peeling force Pa between the film (A) and the film (B) in the Tov multilayer film of this embodiment was measured. The results are shown in Table 1. From the results in Table 1, it can be seen that the NZ coefficient of the obtained optical film is between 0 and 1.

[Example 3]

The temperature Tov in the oven was changed from 126°C to 130°C, and the stretching ratio was changed from 1.00 times to 1.02 times for stretching. In addition, an optical film was obtained and evaluated by the same operation as in Example 2. The peeling speed in the peeling step is 1 m/min. The results are shown in Table 1. From the results in Table 1, it can be seen that the NZ coefficient of the obtained optical film is between 0 and 1.

[Example 4]

The multilayer film (C)-4 obtained in Manufacturing Example 10 was unrolled from a roll, transported in the film longitudinal direction, and supplied to the same longitudinal stretching machine as used in Example 1. Transport the multilayer film (C)-4 to the oven of the longitudinal stretching machine. During transportation, the temperature Tov in the oven was set to 135°C and the stretching ratio was 1.07 times for stretching.

Next, the peeling step is performed near the exit in the oven. The peeling step is performed by pulling the film (B)-2 on both sides of the multilayer film (C)-4 and continuously peeling the film (B)-2 from the film (A)-2. The direction of pulling the two films (B)-2 is the direction perpendicular to the surface of the film (A)-2 being conveyed, and the directions are opposite to each other. Thereby, peeling by applying a force in the thickness direction of the film (A)-2 is performed to extend the film (A)-2 in the thickness direction. The peeling speed is 1 m/min. As a result, a film (A)-2 stretched in the thickness direction was obtained as an optical film.

Measure the in-plane retardation Re, thickness and NZ coefficient of the obtained optical film. Furthermore, the peeling force Pa between the film (A) and the film (B) in the Tov multilayer film of this embodiment was measured. The results are shown in Table 1. From the results in Table 1, it can be seen that the NZ coefficient of the obtained optical film is between 0 and 1.

[Example 5]

The temperature Tov in the oven was changed from 126°C to 135°C, and the stretching ratio was changed from 1.00 times to 1.07 times for stretching. In addition, an optical film was obtained and evaluated by the same operation as in Example 2. The peeling speed in the peeling step is 5 m/min. The results are shown in Table 1. From the results in Table 1, it can be seen that the NZ coefficient of the obtained optical film is between 0 and 1.

[Example 6]

The multilayer film (C)-5 obtained in Manufacturing Example 11 was unrolled from a roll, transported in the film longitudinal direction, and supplied to the same longitudinal stretching machine as that used in Example 1. Transport the multilayer film (C)-5 to the oven of the longitudinal stretching machine. During transportation, the temperature Tov in the oven was set to 140°C and the stretching ratio was 1.07 times for stretching.

Next, the peeling step is performed near the exit in the oven. The peeling step is performed by pulling the film (B)-2 on both sides of the multilayer film (C)-5 and continuously peeling the film (B)-2 from the film (A)-3. The direction of pulling the two films (B)-2 is the direction perpendicular to the surface of the film (A)-3 being conveyed, and the directions are opposite to each other. Thereby, peeling with a force applied in the thickness direction of the film (A)-3 is performed to extend the film (A)-3 in the thickness direction. The peeling speed is 1 m/min. As a result, a film (A)-3 stretched in the thickness direction was obtained as an optical film.

Measure the in-plane retardation Re, thickness and NZ coefficient of the obtained optical film. Furthermore, the peeling force Pa between the film (A) and the film (B) in the Tov multilayer film of this embodiment was measured. The results are shown in Table 1. From the results in Table 1, it can be seen that the NZ coefficient of the obtained optical film is between 0 and 1.

[Comparative Example 1]

The multilayer film (C)-1 obtained in Manufacturing Example 7 was unwound from a roll, transported in the film longitudinal direction, and supplied to the same longitudinal stretching machine as that used in Example 1. Transport the multilayer film (C)-1 to the oven of the longitudinal stretching machine. During transportation, the temperature Tov in the oven was set to 135°C and the stretching ratio was 1.07 times for stretching.

Furthermore, although the peeling step was attempted near the exit of the oven, the multilayer film (C)-1 that reached the exit of the oven produced the peeling of the film (B)-1, and the whole film (A)-1 Wrinkles are generated, and the peeling step cannot be performed.

In addition, the peeling force Pa between the film (A) and the film (B) in the Tov multilayer film of this embodiment was measured. The results are shown in Table 1.

[Comparative Example 2]

The multilayer film (C)-6 obtained in Manufacturing Example 12 was unrolled from a roll, transported in the film longitudinal direction, and supplied to the same longitudinal stretching machine as used in Example 1. Transport the multilayer film (C)-6 to the oven of the longitudinal stretching machine. During transportation, the temperature Tov in the oven was set to 135°C and the stretching ratio was 1.07 times for stretching.

Furthermore, although the peeling step was attempted near the exit in the oven, the interface between the film (A) and the adhesive layer could not be peeled smoothly, and the adhesive remained on the surface of the film (A) after peeling, and it could not perform well. Manufacturing of optical film.

In addition, the peeling force Pa between the film (A) and the film (B) in the Tov multilayer film of this embodiment was measured. The results are shown in Table 1.

[Comparative Example 3]

The temperature Tov in the oven was changed from 126°C to 120°C, and an optical film was obtained and evaluated by the same operation as in Example 2. The peeling speed in the peeling step is 5 m/min. The results are shown in Table 1. It can be seen from the results in Table 1 that the NZ coefficient of the obtained optical film is 1.6, which is a value greater than 1.

In addition, the peeling force Pa between the film (A) and the film (B) in the Tov multilayer film of this embodiment was measured. The results are shown in Table 1.

The results of the examples and comparative examples are collectively disclosed in Table 1.

【Table 1】

The meanings of the abbreviations in the table are as follows.

COP: A resin containing an alicyclic structure polymer (a resin with a glass transition temperature of 126°C and a lower ene polymer, trade name "ZEONOR", manufactured by Zeon Co., Ltd.).

PET: Polyester resin ("PET-G 6763" manufactured by EASTMAN).

OPP: Self-adhesive stretched polypropylene film (manufactured by FUTAMURA Chemical Co., Ltd., trade name "FSA 010M #30").

It can be seen from the results in Table 1 that the relationship between Tov and TgA and the value of Pa meet the requirements of the application in the extended embodiment of the application. The optical film with 0<Nz<1 can be easily manufactured.

100‧‧‧Multilayer film 111‧‧‧film (B) 112‧‧‧film (B) 121‧‧‧adhesive layer 122‧‧‧adhesive layer 131‧‧‧film (A) 132‧‧‧optical film 151‧‧‧Roller at the upstream of the stripping area 152‧‧‧Roller at the upstream of the stripping area 161‧‧‧Roller at the downstream of the stripping area 162‧‧‧Roller at the downstream of the stripping area 211‧‧‧Film (B) 221‧‧‧Adhesive layer 232‧‧‧Optical film P‧‧‧Peeling area

FIG. 1 is a side view schematically showing an example of the peeling device for performing the peeling step in the manufacturing method of the present invention and the operation of the peeling step using the device. 2 is a side view schematically showing another example of the peeling device for performing the peeling step in the manufacturing method of the present invention and another example of the operation of the peeling step using the device.

100: Multilayer film

111: Film (B)

112: Film (B)

121: Adhesive layer

122: Adhesive layer

131: Film (A)

132‧‧‧Optical Film

151‧‧‧The roller upstream of the stripping area

152‧‧‧The roller upstream of the stripping area

161‧‧‧The roll downstream of the stripping area

162‧‧‧The roller downstream of the stripping area

P‧‧‧Peeling area

Claims (3)

A manufacturing method of an optical film, including the peeling step of providing a multilayer film in a peeling process; the multilayer film includes a film (A) made of a thermoplastic resin A and a film set on one or both sides of the film (A) The multilayer film of (B); the peeling treatment includes peeling the film (B) from the film (A) at a temperature of Tov (°C) by pulling the film (A) in the thickness direction and extending the film (B) in the thickness direction; the The temperature Tov and the glass transition temperature TgA(℃) of the film (A) satisfy the relationship Tov≧TgA; in the multilayer film, the peeling angle of the film (A) and the film (B) at the temperature Tov is 180 °, the peeling force Pa at a stretching speed of 300mm/min is 0.03N/50mm or more and 0.5N/50mm or less. The method of manufacturing an optical film according to claim 1, wherein the thermoplastic resin A contains an alicyclic structure-containing polymer. The method for manufacturing an optical film according to claim 1 or 2, further comprising an extension step of extending the multilayer film in the in-plane direction of the multilayer film.

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