KR102287915B1 - Optical film manufacturing method, polarizing plate, and display device - Google Patents

Abstract

A peeling step of subjecting the multilayer film to a peeling treatment, wherein the multilayer film comprises a film (A) made of a thermoplastic resin A, and a film (B) provided on one or both surfaces of the film (A) It is a long multilayer film, and the peeling process includes peeling the film (B) from the film (A) at a temperature Tov (°C) so that a force is applied in the thickness direction of the film (A) and the temperature Tov and the glass transition temperature TgA (°C) of the film (A) satisfy the relationship of Tov ≥ TgA, and the film (B) has a shrinkage ratio Xb of 0% or more and less than 4%, The said shrinkage rate Xb is the shrinkage rate of the width direction of the said film (B) when the said film (B) is processed under the conditions of temperature Tov and 60 second, The manufacturing method of an optical film; And a polarizing plate and display device using the optical film.

Description

Optical film manufacturing method, polarizing plate, and display device

This invention relates to the manufacturing method of an optical film, a polarizing plate, and a display apparatus.

In display devices, such as a liquid crystal display device, providing the resin optical film which has retardation for the objective, such as optical compensation, is widely performed. As a method of providing retardation to a resin film, extending|stretching such a film is performed widely.

As such an optical film, a film in which the NZ coefficient Nz satisfies 0 < Nz < 1, preferably a film of 0.4 < Nz < 1, more ideally a film of Nz = 0.5 is required in some cases. However, when the film is stretched by a conventional method, the value of the NZ coefficient becomes a value smaller than 0 or a value larger than 1, so it is difficult to obtain a film of 0 < Nz < 1 .

As a method of obtaining the film of 0<Nz<1, employ|adopting the multilayer film which combined several films is considered. However, it is desired to realize a film of 0 < Nz < 1 with a simpler single-layer structure.

As a method of realizing a film of 0 < Nz < 1 with a single-layer film, the method described in Patent Document 1 is known. In Patent Document 1, a shrink film is bonded to a resin film to be processed, and thereafter, the shrink film is contracted, thereby shrinking the resin film, and as a result, 0 < Nz < 1 is achieved.

Japanese Laid-Open Patent Publication No. Hei 08 - 207119 (corresponding foreign publication: European Patent Application Laid-Open No. 0707938 Specification)

However, with the method described in Patent Document 1, it is difficult to control the shrinkage force of the shrink film, and the process for shrinking the shrink film is complicated, so it is difficult to simply produce a film having 0 < Nz < 1 .

Accordingly, an object of the present invention is to provide a method for manufacturing an optical film capable of easily manufacturing an optical film having 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 optical compensation function, and a display device that can be easily manufactured and has high optical compensation.

MEANS TO SOLVE THE PROBLEM This inventor investigated in order to solve the said subject. As a result, this inventor discovered that this subject could be solvable by extending|stretching a film in the thickness direction using the peeling force of a film as a manufacturing method of an unprecedented optical film. Moreover, it discovered that operation of favorable thickness direction extending|stretching could be performed by making the characteristic of the film to peel and the temperature at which extending|stretching to such a thickness direction is made specific. The present invention has been made based on these findings.

That is, this invention is as follows.

[1] including a peeling step of subjecting the multilayer film to a peeling treatment,

The multilayer film is a long multilayer film comprising a film (A) made of a thermoplastic resin A, and a film (B) provided on one or both surfaces of the film (A),

The peeling treatment includes peeling the film (B) from the film (A) at a temperature Tov (°C) so that a force is applied in the thickness direction of the film (A),

The temperature Tov and the glass transition temperature TgA (°C) of the film (A) satisfy the relationship Tov ≥ TgA,

The film (B) has a shrinkage ratio Xb of 0% or more and less than 4%, and the shrinkage ratio Xb is the width of the film (B) when the film (B) is treated under the conditions of a temperature Tov and 60 seconds. direction of shrinkage,

A method of manufacturing an optical film.

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

[3] The method for producing the optical film according to [1] or [2], further comprising a stretching step of stretching the multilayer film in the in-plane direction.

[4] A polarizing plate comprising an optical film and a polarizer manufactured by the manufacturing method according to any one of [1] to [3].

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

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the optical film which can manufacture easily the optical film of 0<Nz<1; a polarizing plate that can be easily manufactured and has a high optical compensation function; In addition, a display device that can be easily manufactured and has high optical compensation is provided.

BRIEF DESCRIPTION OF THE DRAWINGS It is a side view which shows typically the peeling apparatus which performs the peeling process in the manufacturing method of this invention, and an example of peeling process operation using this apparatus.
It is a side view which shows typically the peeling apparatus which performs the peeling process in the manufacturing method of this invention, and another example of peeling process operation using this apparatus.

Hereinafter, the present invention will be described in detail by showing embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and can be arbitrarily changed and implemented without departing from the scope of the claims of the present invention and its equivalents.

In the following description, the in-plane retardation Re of the film is a value expressed by Re = (nx - ny) × d, unless otherwise specified, and the retardation Rth in the thickness direction of the film is , Rth = {(nx + ny)/2 - nz} x d. In addition, the NZ coefficient Nz of a film is a value represented by Nz = (nx - nz)/(nx - ny), and can also be represented by Nz = (Rth/Re) + 0.5. Here, nx represents the refractive index of the direction which gives the maximum refractive index as a direction perpendicular|vertical to the in-plane direction of a film, ie, thickness direction. ny represents the refractive index of the direction orthogonal to the direction of nx as the said in-plane direction. nz represents the refractive index in the thickness direction. d represents the thickness of the film. The measurement wavelength is 590 nm, unless otherwise stated.

In the following description, unless otherwise indicated, a "polarizing plate" includes not only a rigid member but also a member having flexibility such as, for example, a resin film.

In the following description, a "long" film refers to a film having a length of 5 times or more with respect to the width, and preferably has a length of 10 times or more, and specifically, the extent to which it is wound in a roll and stored or transported. A film with a length of The upper limit of the length of the long film is not particularly limited, and can be, for example, 100,000 times or less with respect to the width.

In this technical field, "stretching" of a film usually means the operation of deforming a film so that the shape of a film may expand in one or more directions of the in-plane direction of a film. However, in the present application, "stretching" of the film is not limited thereto, and the film is deformed so as to extend the shape of the film in a direction other than the in-plane direction (a direction non-parallel to the in-plane direction of the film, for example, the thickness direction). It also includes operations that make In the following description, when it is clear from context, the operation which deforms a film so that it may expand the shape of a film in one or more directions of the normal in-plane direction of a film is simply called "stretching". On the other hand, the process of deforming the film so as to expand the shape of the film in a direction other than the in-plane direction, as distinguished from such normal "stretching", is called "thickness direction stretching", and the film subjected to such processing is referred to as "thickness direction stretching". It's called 'film'.

[One. Manufacturing method of optical film]

The manufacturing method of the optical film of this invention includes the peeling process of providing a specific multilayer film to a specific peeling process.

[1.1. multilayer film]

The multilayer film used for a peeling process is a long multilayer film containing the film (A) which consists of a thermoplastic resin A, and the film (B) provided in one or both surfaces of the film (A).

[1.1.1. Film (A)]

The thermoplastic resin A constituting the film (A) is not particularly limited, and a resin containing various polymers capable of imparting desired physical properties as an optical film can be appropriately selected and employed.

Preferred examples of the polymer contained in the thermoplastic resin A include an alicyclic structure-containing polymer.

The alicyclic structure-containing polymer is a polymer having an alicyclic structure in the repeating unit, and either a polymer containing an alicyclic structure in the main chain or a polymer containing an alicyclic structure in the side chain can be used. The alicyclic structure-containing polymer may include a crystalline resin and an amorphous polymer. An amorphous alicyclic structure-containing polymer is preferable from a viewpoint of obtaining the desired effect of this invention, and a viewpoint of manufacturing cost.

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

Although there is no restriction|limiting in particular in the carbon number which comprises one repeating unit of an alicyclic structure, Usually 4-30, Preferably it is 5-20, More preferably, it is 6-15.

The proportion of the repeating unit having an alicyclic structure in the alicyclic structure-containing polymer is appropriately selected depending on the intended use, but is usually 50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight or more. By increasing in this way the repeating unit which has an alicyclic structure, the heat resistance of a base film can be improved.

The alicyclic structure-containing polymer is specifically, (1) norbornene polymer, (2) monocyclic cyclic olefin polymer, (3) cyclic conjugated diene polymer, (4) vinyl alicyclic hydrocarbon polymer, hydrides thereof, etc. can be heard Among these, from a viewpoint of transparency and a moldability, a norbornene polymer and these hydrides are more preferable.

As a norbornene polymer, For example, the ring-opened polymer of a norbornene monomer, a ring-opened copolymer of a norbornene monomer, and other monomers capable of ring-opening copolymerization, and their hydrides; The addition copolymer of the addition polymer of a norbornene monomer, a norbornene monomer, and other monomer copolymerizable, etc. are mentioned. Among these, from a viewpoint of transparency, the ring-opened polymer hydride of a norbornene monomer is especially preferable.

As an example of the said alicyclic structure containing polymer, the polymer disclosed in Unexamined-Japanese-Patent No. 2002-321302 is mentioned, for example.

Moreover, as an example of a crystalline alicyclic structure containing polymer, the polymer disclosed in Unexamined-Japanese-Patent No. 2016-26909 is mentioned.

As another example of the polymer contained in the thermoplastic resin A, general-purpose polymers, such as a triacetyl cellulose and a polystyrene type polymer, are mentioned. In particular, among polystyrene-based polymers, a polystyrene-based polymer having a syndiotactic structure can be preferably employed. Examples of the polystyrene-based polymer having a syndiotactic structure include a polymer disclosed in Japanese Patent Application Laid-Open No. 2014-186273.

Although the weight average molecular weight of the polymer contained in the thermoplastic resin A is not specifically limited, Preferably it is 10000 or more, More preferably, it is 20000 or more, On the other hand, Preferably it is 300000 or less, More preferably, it is 250000 or less. When the weight average molecular weight is within this range, the thermoplastic resin A excellent in mechanical strength and moldability can be easily obtained.

The thermoplastic resin A may consist only of the polymer which is a main component, such as the above-mentioned, However, As long as the effect of this invention is not impaired remarkably, it may contain arbitrary compounding agents. The ratio of the polymer which is a main component in resin becomes like this. Preferably it is 70 weight% or more, More preferably, it is 80 weight% or more.

As the thermoplastic resin A, from among various commercially available products, those having desired properties can be appropriately selected and employed. Examples of such commercially available products include product groups under the trade name "Zeonoa" (manufactured by Nippon Zeon Corporation), the trade name "Topas" (manufactured by Polyplastics Corporation), and the trade name "Aton" (manufactured by JSR Corporation).

The glass transition temperature TgA of the thermoplastic resin A is preferably 100°C or higher, more preferably 110°C or higher, and preferably 180°C or lower, more preferably 170°C or lower. When TgA is in such a range, processing, such as thickness direction extending|stretching, can be performed smoothly, and the optical film which has a desired optical body characteristic can be obtained easily.

The thickness of the film (A) is preferably 10 µm or more, more preferably 20 µm or more, while preferably 200 µm or less, more preferably 190 µm or less. When the thickness of the film (A) is within such a range, it is possible to smoothly perform processing such as stretching in the thickness direction, and easily obtain an optical film having a desired optical body characteristic.

The method of manufacturing a film (A) is not specifically limited, Arbitrary manufacturing methods are employable. For example, the film (A) can be manufactured by shape|molding the thermoplastic resin A into a desired shape. As a preferable example of the shaping|molding method for shape|molding resin A, extrusion molding is mentioned. By performing extrusion molding, the film (A) which has a desired dimension can be manufactured efficiently.

[1.1.2. Film (B)]

It does not specifically limit as a material which comprises the film (B), A resin containing various polymers suitable for implementation of this invention can be selected suitably and it can be employ|adopted. In the following, this resin is simply referred to as "resin B".

As resin B, a thermoplastic resin can be used. Examples of the polymer contained in the resin B and preferable ranges of the molecular weight thereof include the same examples as those given above as examples of the alicyclic structure-containing polymer and other polymers contained in the thermoplastic resin A.

Further examples of the alicyclic structure-containing polymer contained in the resin B include two or more polymer blocks having a cyclic hydrocarbon group-containing compound hydride unit [I], and a chain hydrocarbon compound hydride unit [II], or a unit [I]. ] and a hydrogenated block copolymer comprising at least one polymer block having a combination of units [II]. As a specific example of such a hydrogenated block copolymer, the polymer disclosed in International Publication No. WO 2016/152871 is mentioned, for example.

General-purpose polymers, such as a polypropylene, a (meth)acrylate polymer, and a polyimide, are mentioned as an example of the polymer contained in resin B further. As the resin B, from among various commercially available products, those having desired properties can be appropriately selected and employed. As an example of such a commercial item, a self-adhesive stretched polypropylene film (For example, the Futamura Chemical Co., Ltd. make, brand name "FSA 010M #30") is mentioned.

As for the film (B) in a multilayer film, the shrinkage rate Xb is a value within the specific range. The shrinkage rate Xb is the shrinkage rate in the width direction of the film (B) when the film (B) is processed under the conditions of temperature Tov and 60 seconds. Here, temperature Tov is the temperature of the film in the peeling process of the manufacturing method of this invention.

The shrinkage ratio Xb is 0% or more, preferably 0.3% or more, more preferably 0.5% or more, still more preferably 1.4% or more, while less than 4%, preferably 3.9% or less, more preferably 3.8 % or less. When the shrinkage rate Xb is within such a range, generation of wrinkles in the process up to the peeling process is suppressed, and unintentional peeling of the film (B) in a step before the peeling process is suppressed, and the desired thickness direction elongation is achieved. A force can be imparted to the film (A). The shrinkage rate Xb can be calculated|required by heat-processing the sample of the film (B) at the temperature Tov for 60 second, measuring the dimension before and behind heat processing, and calculating their ratio.

The thickness of the film (B) is preferably 10 µm or more, more preferably 15 µm or more, while preferably 100 µm or less, more preferably 90 µm or less. When the thickness of the film (B) is within such a range, it is possible to smoothly perform a treatment such as stretching in the thickness direction, and easily obtain an optical film having a desired optical body characteristic.

The method of manufacturing a film (B) is not specifically limited, Arbitrary manufacturing methods are employable. For example, the film (B) can be manufactured by shape|molding resin B into a desired shape. As a preferable example of the shaping|molding method for shape|molding resin B, extrusion molding is mentioned. By performing extrusion molding, the film (B) which has a desired dimension can be manufactured efficiently.

[1.1.3. other floors]

A multilayer film can contain arbitrary layers in addition to films (A) and (B). For example, it may include a pressure-sensitive adhesive layer. As the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, various commercially available pressure-sensitive adhesives can be used. Specifically, as a polymer as a main component, an adhesive containing an acrylic polymer can be used. For example, from a commercially available film having an adhesive layer (for example, Fujimori Kogyo "Mastack Series"), an adhesive layer is transferred to the film (A) or film (B), and this is an adhesive layer in a multilayer film can be used as

When a multilayer film has an adhesive layer between films (A) and (B), it is preferable that the adhesive force with respect to the film (B) of this adhesive layer is higher than the adhesive force with respect to a film (A). By having such a difference in adhesive force, the residual of the glue with respect to an optical film can be reduced, and a high-quality optical film can be obtained easily. Such a difference in adhesive force can be obtained by appropriately selecting the material of the pressure-sensitive adhesive layer, and applying appropriate surface treatment to the surfaces of the films (A) and (B) as needed.

[1.1.4. Preparation method of multilayer film]

The method of preparing the multilayer film used for the manufacturing method of this invention is not specifically limited, Arbitrary methods are employable. Such preparation can be performed by bonding together a film (A) and a film (B), for example. Prior to bonding, if necessary, the film (A) and/or the film (B) can be subjected to surface treatment such as corona treatment. Moreover, prior to bonding, an adhesive layer can be formed in the surface of a film (A) and/or a film (B) as needed, and bonding can be performed through this adhesive layer. Bonding can be performed by bonding a long film (A) and a long film (B) by roll-to-roll in alignment with a longitudinal direction.

[1.2. peeling process]

In the peeling process in the manufacturing method of this invention, a multilayer film is used for a peeling process. The peeling process includes peeling the film (B) from the film (A). By performing such a peeling process, the force which pulls the film (A) in the thickness direction can be applied, As a result, thickness direction extending|stretching of the film (A) can be achieved. When a multilayer film has two or more layers of films (B), a multilayered film (B) peels at the same time normally.

BRIEF DESCRIPTION OF THE DRAWINGS It is a side view which shows typically an example of operation of the peeling apparatus which performs the peeling process in the manufacturing method of this invention, and the peeling process using this apparatus. In FIG. 1, the elongate multilayer film 100 is conveyed in the arrow A11 direction, and is provided for a peeling process in the peeling area P after that.

The multilayer film 100 is a film (A) 131, a film (B) 111 provided on one surface of the film (A) 131, and the other surface of the film (A) 131 . It includes a film (B) 112 installed on the. The multilayer film 100 also includes adhesive layers 121 and 122 interposed between the films (A) and (B). The thickness of the film (A) 131 in a multilayer film is represented by arrow A14.

The process of peeling in a peeling process can be performed by pulling the film B in the direction different from the in-plane direction of the film A conveyed. In the example of FIG. 1, in the peeling area|region P, the film (B) 111 is pulled in the arrow A12 direction along the longitudinal direction, and also the film (B) 112 is the longitudinal direction. It is being towed in the direction of the arrow A13. Thereby, peeling advances toward upstream from the downstream of the conveyance direction of a multilayer film, and it can peel so that the film (B)111 and 112 may be applied to the thickness direction of the film (A)131. The force in the thickness direction of the film as used herein is a force in a direction non-parallel to the in-plane direction of the film, and is preferably a direction close to a direction perpendicular to the surface of the film. As a result of this peeling process, the optical film 132 extended|stretched in the thickness direction is obtained. In addition, by balancing the traction force in the direction of the arrow A12 and the traction force in the direction of the arrow A13, these tractions are applied to the multilayer film 100 and the optical film 132. Undesired tension in the in-plane direction is not applied. can be done without

In the example of FIG. 1, the thickness of the optical film 132 is represented by arrow A15. The optical film 132 has a thicker thickness than the film (A) 131 in the multilayer film 100 as a result of thickness direction extending|stretching. However, the manufacturing method of the present invention is not limited thereto. For example, when the peeling step also involves stretching in the in-plane direction, the thickness of the optical film does not necessarily become thicker than the thickness of the film (A), but even in such a case, the optical film of 0 < Nz < 1 There may be cases where this is obtained.

The optical film 132 obtained as a result of the peeling process in peeling area|region P is further conveyed in arrow A11 direction. The multilayer film 100 and the optical film 132 are conveyed in the state held by the nip rolls 151 and 152 of the upstream of a peeling area|region, and the nip rolls 161 and 162 of the downstream of a peeling area|region. The conveying speed can be adjusted by appropriately adjusting the circumferential speed of these nip rolls.

Moreover, as needed, the circumferential speed of a downstream nip roll can be adjusted to the speed faster than the circumferential speed of an upstream nip roll. By performing such adjustment, desired tension|tensile_strength can be provided to the multilayer film 100 and the optical film 132. If necessary, by adjusting this tension, the stretching process in the film longitudinal direction according to the peeling process can be performed. Furthermore, as needed, you may extend|stretch to the arbitrary directions in a film plane together with a peeling process or in the upstream or downstream of the peeling area|region P.

In the manufacturing method of the optical film of this invention, in addition to thickness direction extending|stretching, the draw ratio in the case of performing in-plane direction extending|stretching can be suitably adjusted according to the desired optical performance requested|required to provide to an optical film. A specific draw ratio becomes like this. Preferably it is 1 time or more, More preferably, it is 1.01 time or more, On the other hand, Preferably it is 2 time or less, More preferably, it is 1.8 times or less. When the draw ratio in the in-plane direction is within such a range, desired optical performance can be easily obtained.

In the peeling apparatus, when performing the peeling process continuously with respect to the elongate multilayer film, the peeling area P can be set to the position where the peeling apparatus is by balancing the conveyance speed of a multilayer film and the speed of peeling. In that case, the conveyance speed of a multilayer film turns into a peeling speed. A peeling rate can be suitably adjusted according to the desired optical performance requested|required to provide to an optical film. The specific peeling speed is preferably 1 m/min or more, more preferably 2 m/min or more, while preferably 50 m/min or less, and more preferably 40 m/min or less. When the peeling rate is within this range, desired optical performance can be easily obtained.

In the manufacturing method of the optical film of this invention, a peeling process is performed at the temperature Tov (degreeC). The temperature Tov and the glass transition temperature TgA (°C) of the film (A) satisfy the relationship of Tov≥TgA. Tov is preferably (TgA+3)°C or higher, and more preferably (TgA+5)°C or higher. By adjusting Tov in such a range, optical properties, such as a desired NZ coefficient, can be easily provided to an optical film. Although the upper limit of Tov is not specifically limited, For example, it can be (TgA+40) degreeC or less. Temperature Tov in a peeling process can be adjusted by heating the temperature in oven (not shown) which surrounds the area|region containing a peeling area|region in a peeling apparatus with an appropriate heating apparatus.

It is a side view which shows typically the peeling apparatus which performs the peeling process in the manufacturing method of this invention, and another example of peeling process operation using this apparatus. In FIG. 2, the elongate multilayer film 200 is conveyed in the arrow A21 direction, and is provided for a peeling process in the peeling area P after that. The multilayer film 200 includes a film (A) 231 and a film (B) 211 provided on one surface of the film (A) 231 , the other side of the film (A) 231 . The film (B) is not provided on the surface of The multilayer film 200 also includes an adhesive layer 221 interposed between the films (A) and (B). The thickness of the film (A) 231 in a multilayer film is represented by arrow A24.

In this example, since the multilayer film 200 has a film (B) 211 only on the one surface, the peeling process in a peeling process carries out this film (B) 211, It carries out by pulling in the direction of arrow A22 which is a direction different from the in-plane direction of the film A. Therefore, tension is applied to the multilayer film 200 and the optical film 232 after the peeling process by the nip rolls 151 and 152 upstream of the peeling region and nip rolls 161 and 162 downstream of the peeling region, It is opposing the pulling of the film (B) 211 by this tension|tensile_strength. As a result of this peeling process, the film (A) 231 is extended|stretched in the thickness direction, and the optical film 232 is obtained. The optical film 232 has a thickness indicated by an arrow A25 which is thicker than the film (A) 231 .

[2. optical film]

According to the manufacturing method of this invention, the optical film whose NZ coefficient Nz is 0<Nz<1 can be manufactured easily. Nz is more preferably 0.4<Nz<1, and ideally Nz=0.5. While it is difficult to manufacture the optical film which has such an NZ coefficient by extending|stretching the film in the normal in-plane direction, it can be used usefully for the objective, such as optical compensation of a display device. Therefore, the manufacturing method of this invention exhibits a high effect from a viewpoint that manufacture is difficult and can manufacture a useful product easily.

In-plane retardation Re of an optical film becomes like this. Preferably it is 100 nm or more, More preferably, it is 120 nm or more, On the other hand, Preferably it is 350 nm or less, More preferably, it is 300 nm or less. When Re is within this range, an optical film that can be usefully used for purposes such as optical compensation can be configured. The retardation Rth in the thickness direction of the optical film is preferably -80 nm or more, more preferably -70 nm or more, and preferably 80 nm or less, more preferably 70 nm or less. When Re is in such a range, an optical film having desired properties such as Nz coefficient and useful for optical compensation and the like can be constituted.

[3. Applications of Optical Film: Polarizing Plates and Display Devices]

The optical film obtained by the manufacturing method of this invention can be used as a component of optical devices, such as a display apparatus. For example, optical components, such as a polarizing plate, can be comprised by combining an optical film and another member.

The polarizing plate of this invention is equipped with the optical film manufactured by the manufacturing method of the said this invention, and a polarizer. The polarizing plate of this invention can be manufactured by bonding an optical film and a polarizer together.

Prior to bonding with a polarizing plate, arbitrary layers can be formed in the surface of an optical film. As an example of arbitrary layers, the hard-coat layer which raises the surface hardness of a film, the mat layer which improves the sliding property of a film, and an antireflection layer are mentioned.

The polarizing plate of this invention may further be equipped with the adhesive bond layer for adhering these between the film cut out from the optical film, and a polarizer.

A polarizer is not specifically limited, Arbitrary polarizer can be used. As an example of a polarizer, after making materials, such as an iodine and a dichroic dye, adsorb|suck to a polyvinyl alcohol film, what carried out the extending|stretching process is mentioned. As an adhesive agent which comprises an adhesive bond layer, what used various polymers as a base polymer is mentioned. Examples of such base polymers include, for example, acrylic polymers, silicone polymers, polyesters, polyurethanes, polyethers, and synthetic rubbers.

A polarizing plate can be equipped with a protective film. Although the number of the polarizer and protective film with which a polarizing plate is equipped is arbitrary, the polarizing plate of this invention can be equipped with one layer of polarizer and two layers of protective films provided on the both surfaces normally. The film cut out from the optical film of this invention may be sufficient among these two layers of protective films, and the film cut out from the optical film of this invention may be sufficient as either one.

The display device of this invention is equipped with the optical film manufactured by the manufacturing method of the said this invention. The display device of the present invention may preferably include the polarizing plate of the present invention. The display device of the present invention can be suitably configured by combining the optical film of the present invention with other components of the display device.

The display device of the present invention is preferably a liquid crystal display device. Examples of the liquid crystal display device include in-plane switching (IPS) mode, vertical alignment (VA) mode, multi-domain vertical alignment (MVA) mode, continuous pinwheel alignment (CPA) mode, hybrid alignment nematic (HAN) mode. A liquid crystal display device provided with the liquid crystal cell of drive systems, such as a mode, a twisted nematic (TN) mode, a super twisted nematic (STN) mode, and an optical compensating bend (OCB) mode, is mentioned.

When the display device of the present invention is a liquid crystal display device, the polarizing plate can be provided as a layer for transmitting only desired specific polarized light among the light incident on the liquid crystal cell and the light emitted from the liquid crystal cell. The polarizing plate can also be installed as part of a component for preventing reflection of external light.

The display device of the present invention may further be an organic electroluminescent display device. In this case, for example, the polarizing plate of the present invention is provided as a part of a component for preventing reflection of external light.

Example

Hereinafter, the present invention will be specifically described with reference to Examples. However, this invention is not limited to the Example shown below, The range which does not deviate from the Claim of this invention and its equivalent range can be changed arbitrarily and can be implemented.

In the following description, "%" and "part" indicating the amount are by weight unless otherwise specified. In addition, the operation demonstrated below was performed under conditions of normal temperature and normal pressure, unless otherwise indicated.

[Assessment Methods]

(Method for measuring glass transition temperature of resin)

The pellet of the resin to be measured was prepared, and the glass transition temperature of the resin pellet was measured using a differential scanning calorimeter ("DSC6220" manufactured by Seiko Instruments). The conditions were a sample weight of 10 mg and a temperature increase rate of 20°C/min.

(Method of measuring phase difference and NZ coefficient)

Re and Rth were measured at a wavelength of 590 nm using a phase difference measuring apparatus (product name "Axoscan" by Axometric), and the NZ coefficient was calculated|required based on them.

(Measuring method of shrinkage rate Xb)

A long film to be measured was cut out to obtain a slice of length direction × width direction = 120 mm × 120 mm. The four corners of the rectangle 10 mm inside the section were marked with an oil-based pen. That is, the square had dimensions of 100 mm x 100 mm, and was located in the center of the section, and each side of the square was parallel to the side of the section.

Thereafter, the distance between the four marks was measured using a universal projector ("V-12BDC" manufactured by Nikon Corporation). Thereafter, the sample was placed in an oven and heated at a predetermined temperature for 60 seconds. After the heat treatment, the distance between the four marks was measured again. The shrinkage rate Xb was calculated|required from ratio of the distance in the width direction before heat processing and after heat processing. Shrinkage Xb(%) = ((Distance before treatment - Distance after treatment) / Distance before treatment) × 100

[Preparation Example 1. Preparation of Film (A)-1]

Pellets of a resin containing an alicyclic structure-containing polymer (a norbornene polymer resin having a glass transition temperature of 126°C, trade name “Zeonoa”, manufactured by Nippon Zeon Corporation) were dried at 100°C for 5 hours. Thereafter, the dried resin pellets were supplied to a single screw extruder. After the resin was melted in an extruder, it was extruded from a T die into a sheet on a casting drum through a polymer pipe and a polymer filter, and cooled. Thus, a long film (A)-1 having a thickness of 80 µm and a width of 1000 mm was obtained. The manufactured film (A)-1 was wound up in roll shape and collect|recovered.

[Preparation Example 2. Preparation of Film (A)-2]

The same operation as in Production Example 1 was performed except that the width of the opening of the nozzle of the T-die was changed. Thereby, a long film (A)-2 having a thickness of 185 µm and a width of 1000 mm was obtained, wound up in a roll shape, and recovered.

[Preparation Example 3. Preparation of Film (A)-3]

The same operation as in Production Example 1 was performed except that the width of the opening of the nozzle of the T-die was changed. Thereby, a long film (A)-3 having a thickness of 133 µm and a width of 1000 mm was obtained, wound up in a roll shape, and recovered.

[Production Example 4. Preparation of raw material film of film (B)]

The pellets of the polyester resin ("PET-G 6763" by Eastman) were dried at 120 degreeC for 5 hours. The dried pellets were fed to the extruder, melted in the extruder, passed through a polymer pipe and a polymer filter under the condition of a resin temperature of 260° C., and extruded from the T die into a sheet on a casting drum, and cooled. Thus, a raw film having a thickness of 60 µm and a width of 1400 mm was obtained.

[Preparation Example 5. Preparation of Film (B)-1]

The raw film obtained in Production Example 4 was continuously supplied to a roll-type longitudinal stretching apparatus. Using this longitudinal stretching machine, the raw film was stretched in the longitudinal direction under the conditions of a stretching temperature of 80°C and a draw ratio of 2 times. The both ends of the extended|stretched film width direction were trimmed, and also corona-treated to the surface of one side. Thus, a long film (B)-1 having a width of 900 mm and a thickness of 42 μm was obtained. As a result of measuring the shrinkage ratio under the conditions of 135°C x 60 seconds in the air of this film (B)-1, the shrinkage ratio Xb in the film width direction was 2%. This film (B) was recovered by winding the film (B) into a roll with the corona-treated surface inside.

[Preparation Example 6. Preparation of Film (B)-2]

The raw film obtained in Production Example 4 was continuously supplied to a tenter-type transverse stretching apparatus. Using this transverse stretching machine, it extended|stretched in the film width direction on the conditions of a extending|stretching temperature of 80 degreeC, and a draw ratio of 2 times. Then, the both ends of the film width direction were trimmed, and also corona-treated on one side, and the long film (B)-2 with a width of 1000 mm and a thickness of 30 micrometers was obtained. As a result of measuring the shrinkage rate under the conditions of 135°C x 60 seconds in the air of the film (B)-2, the shrinkage rate Xb in the film width direction was 20%. This film (B)-2 was recovered by winding the corona-treated surface into a roll shape.

[Preparation Example 7. Preparation of multilayer film (C)-1]

The film (B)-1 obtained in Production Example 5 was unwound from the roll, and the pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer of “Mastack Series” manufactured by Fujimori Industries) was transferred to the corona-treated side of the film (B)-1. Moreover, on both surfaces of the film (A)-1 obtained by manufacture example 1, the film (B)-1 was bonded together by the conventional method through the adhesive layer. Thereby, (film (B)-1) / (adhesive layer) / (film (A) - 1) / (adhesive layer) / (film (B) - 1) elongate multilayer film (C) ) - 1 was obtained. This multilayer film (C)-1 was wound up in roll shape and collect|recovered. The thickness of each layer was 42 µm/25 µm/80 µm/25 µm/42 µm.

[Production Example 8. Preparation of multilayer film (C)-2]

The film (B)-2 obtained in Production Example 6 was unwound from the roll, and the pressure-sensitive adhesive layer (the pressure-sensitive adhesive layer of "Mastack Series" manufactured by Fujimori Kogyo Co., Ltd.) was transferred to the corona-treated side of the film (B)-2. Moreover, on both surfaces of the film (A)-1 obtained by manufacture example 1, the film (B)-2 was bonded together by the conventional method through the adhesive layer. Thereby, (film (B)-2) / (adhesive layer) / (film (A) - 1) / (adhesive layer) / (film (B) - 2) elongate multilayer film (C) ) - 2 was obtained. This multilayer film (C)-2 was wound up in roll shape and collect|recovered. The thickness of each layer was 30 µm/25 µm/80 µm/25 µm/30 µm.

[Preparation Example 9. Preparation of multilayer film (C)-3]

As the film (B)-3, a self-adhesive stretched polypropylene film (“FSA 010M #30” manufactured by Futamura Chemical Company) was prepared. The shrinkage rate Xb in the width direction of the film under the conditions of 120°C × 60 seconds, 126°C × 60 seconds, 130°C × 60 seconds, 135°C × 60 seconds, and 140°C × 60 seconds in the air of this film (B)-3 is , 0.9%, 1.4%, 1.6%, 2.5%, and 3.5%. On both surfaces of the film (A)-1 obtained in manufacture example 1, the film (B)-3 was pasted together by the conventional method. Thereby, the elongate multilayer film (C)-3 which has the layer structure of (film (B)-3) / (film (A)-1) / (film (B)-3) was obtained. This multilayer film (C)-3 was wound up in roll shape and collect|recovered. The thickness of each layer was 30 µm/80 µm/30 µm.

[Production Example 10. Preparation of multilayer film (C)-4]

By the same operation as in Production Example 9, except that the film (A)-2 obtained in Production Example 2 was used instead of the Film (A)-1, (film (B)-3) / (film (A)-2) A long multilayer film (C) - 4 having a layer structure of / (film (B) - 3) was obtained. This multilayer film (C)-4 was wound up in roll shape and collect|recovered. The thickness of each layer was 30 µm/185 µm/30 µm.

[Preparation Example 11. Preparation of multilayer film (C)-5]

By the same operation as in Production Example 9, except that the film (A)-3 obtained in Production Example 3 was used instead of the Film (A)-1, (Film (B)-3) / (Film (A)-3) A long multilayer film (C)-5 having a layer structure of / (film (B)-3) was obtained. This multilayer film (C)-5 was wound up in roll shape and collect|recovered. The thickness of each layer was 30 µm/133 µm/30 µm.

[Example 1]

A floating type longitudinal stretching machine was prepared. This stretching machine is a stretching machine which can extend|stretch the elongate film conveyed in the longitudinal direction in the oven whose temperature was regulated. The multilayer film (C)-1 obtained in Production Example 7 was unwound from a roll, conveyed in the film longitudinal direction, and supplied to the said longitudinal stretching machine. The multilayer film (C)-1 was conveyed in the oven of the longitudinal stretching machine. At the time of conveyance, the oven temperature Tov was 135 degreeC, and it extended|stretched at the draw ratio 1.07 times.

Moreover, the peeling process was performed in the exit vicinity of the oven. The peeling process was performed by pulling the film (B)-1 of both sides of the multilayer film (C)-1, and peeling the film (B)-1 continuously from the film (A)-1. The direction in which the two films (B) - 1 were pulled was a direction perpendicular to the surface of the film (A) - 1 to be conveyed, and was set as a direction opposite to each other. Thereby, peeling with force applied in the thickness direction of the film (A)-1 was performed, and the film (A)-1 was extended|stretched in the thickness direction. The peeling speed was 5 m/min. As a result, the film (A)-1 stretched in the thickness direction was obtained as an optical film.

The in-plane retardation Re, thickness, and NZ coefficient of the obtained optical film were measured. A result is shown in Table 1. As for the obtained optical film, the NZ coefficient was between 0 and 1 so that the result of Table 1 might show.

[Example 2]

The multilayer film (C)-3 obtained in Production Example 9 was unwound from the roll, conveyed in the film longitudinal direction, and supplied to the same longitudinal stretching machine as used in Example 1. The multilayer film (C)-3 was conveyed in the oven of the longitudinal stretching machine. At the time of conveyance, the oven temperature Tov was 126 degreeC. In addition, the draw ratio was made into 1.00 times, ie, conveyance without extending|stretching was performed.

Moreover, the peeling process was performed in the exit vicinity of the oven. The peeling process was performed by pulling the film (B)-3 of both sides of the multilayer film (C)-3, and peeling the film (B)-3 continuously from the film (A)-1. The direction in which the two films (B) - 3 were pulled was a direction perpendicular to the surface of the film (A) - 1 to be conveyed, and was set as a direction opposite to each other. Thereby, peeling with force applied in the thickness direction of the film (A)-1 was performed, and the film (A)-1 was extended|stretched in the thickness direction. The peeling speed was 1 m/min. As a result, the film (A)-1 stretched in the thickness direction was obtained as an optical film.

The in-plane retardation Re, thickness, and NZ coefficient of the obtained optical film were measured. A result is shown in Table 1. As for the obtained optical film, the NZ coefficient was between 0 and 1 so that the result of Table 1 might show.

[Example 3]

An optical film was obtained and evaluated by the same operation as in Example 2 except that the oven temperature Tov was changed from 126°C to 130°C, and the draw ratio was changed from 1.00 times to 1.02 times and stretched. The peeling speed in the peeling process was 1 m/min. A result is shown in Table 1. As for the obtained optical film, the NZ coefficient was between 0 and 1 so that the result of Table 1 might show.

[Example 4]

The multilayer film (C)-4 obtained in Production Example 10 was unwound from the roll, conveyed in the film longitudinal direction, and supplied to the same longitudinal stretching machine as used in Example 1. The multilayer film (C)-4 was conveyed in the oven of the longitudinal stretching machine. At the time of conveyance, the oven temperature Tov was 135 degreeC, and it extended|stretched at the draw ratio 1.07 times.

Moreover, the peeling process was performed in the exit vicinity of the oven. The peeling process was performed by pulling the film (B)-3 of both sides of the multilayer film (C)-4, and peeling the film (B)-3 continuously from the film (A)-2. The direction in which the two films (B) - 3 were pulled was a direction perpendicular to the surface of the film (A) - 2 to be conveyed, and was set as a direction opposite to each other. Thereby, peeling with force applied in the thickness direction of the film (A)-2 was performed, and the film (A)-2 was extended|stretched in the thickness direction. The peeling speed was 1 m/min. As a result, the film (A)-2 extended|stretched in the thickness direction was obtained as an optical film.

The in-plane retardation Re, thickness, and NZ coefficient of the obtained optical film were measured. A result is shown in Table 1. As for the obtained optical film, the NZ coefficient was between 0 and 1 so that the result of Table 1 might show.

[Example 5]

An optical film was obtained and evaluated by the same operation as in Example 2 except that the oven temperature Tov was changed from 126°C to 135°C, and the draw ratio was changed from 1.00 times to 1.07 times and stretching was performed. The peeling speed in the peeling process was 5 m/min. A result is shown in Table 1. As for the obtained optical film, the NZ coefficient was between 0-1 so that the result of Table 1 might show.

[Example 6]

The multilayer film (C)-5 obtained in Production Example 11 was unwound from the roll, conveyed in the film longitudinal direction, and supplied to the same longitudinal stretching machine as used in Example 1. The multilayer film (C)-5 was conveyed in the oven of the longitudinal stretching machine. At the time of conveyance, the oven temperature Tov was 140 degreeC, and it extended|stretched by the draw ratio 1.07 times.

Moreover, the peeling process was performed in the exit vicinity of the oven. The peeling process was performed by pulling the film (B)-3 of both sides of the multilayer film (C)-5, and peeling the film (B)-3 continuously from the film (A)-3. The direction in which the two films (B) - 3 were pulled was a direction perpendicular to the surface of the film (A) - 3 to be conveyed, and was set as a direction opposite to each other. Thereby, peeling with force applied in the thickness direction of the film (A)-3 was performed, and the film (A)-3 was extended|stretched in the thickness direction. The peeling speed was 1 m/min. As a result, the film (A)-3 extended|stretched in the thickness direction was obtained as an optical film.

The in-plane retardation Re, thickness, and NZ coefficient of the obtained optical film were measured. A result is shown in Table 1. As for the obtained optical film, the NZ coefficient was between 0 and 1 so that the result of Table 1 might show.

[Comparative Example 1]

The multilayer film (C)-2 obtained in Production Example 8 was unwound from the roll, conveyed in the film longitudinal direction, and supplied to the same longitudinal stretching machine as used in Example 1. The multilayer film (C)-2 was conveyed in the oven of the longitudinal stretching machine. At the time of conveyance, the oven temperature Tov was 135 degreeC, and it extended|stretched at the draw ratio 1.07 times.

Further, in the vicinity of the outlet in the oven, an attempt was made to perform the peeling process, but in the multilayer film (C) - 2 which reached the vicinity of the outlet in the oven, peeling of the film (B) - 2 occurred, and the film (A) - 1 Wrinkles were generated on the entire surface, and the peeling process could not be performed.

[Comparative Example 2]

An optical film was obtained and evaluated by operation similar to Example 2 except having changed oven temperature Tov from 126 degreeC to 120 degreeC. The peeling speed in the peeling process was 5 m/min. A result is shown in Table 1. As for the obtained optical film so that the result of Table 1 might show, the NZ coefficient was 1.6, and was a value exceeding 1.

The result of an Example and a comparative example is put together in Table 1, and is shown.

The meaning of the abbreviation in a table|surface is as follows.

COP: A resin containing an alicyclic structure-containing polymer (a norbornene polymer resin having a glass transition temperature of 126°C, trade name “Zeonoa”, manufactured by Nippon Zeon Corporation).

PET: Polyester resin ("PET-G 6763" by Eastman Corporation).

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

As is clear from the results in Table 1, in the example of the present application in which stretching was performed under conditions in which the relationship between Tov and TgA and the value of Xb satisfy the requirements of the present application, an optical film having 0 < Nz < 1 can be easily produced. .

100: multilayer film
111: film (B)
112: film (B)
121: adhesive layer
122: adhesive layer
131: film (A)
132: optical film
151: nip roll upstream of peeling area
152: nip roll upstream of peel area
161: nip roll downstream of peel area
162: nip roll downstream of peel area
200: multilayer film
231: film (A)
211: film (B)
221: adhesive layer
232: optical film
P: peel area

Claims (5)

a peeling process of subjecting the multilayer film to a peeling treatment;
The multilayer film is a long multilayer film comprising a film (A) made of a thermoplastic resin A, and a film (B) provided on one or both surfaces of the film (A),
The peeling treatment includes peeling the film (B) from the film (A) at a temperature Tov (°C) so that a force is applied in the thickness direction of the film (A),
The temperature Tov and the glass transition temperature TgA (°C) of the film (A) satisfy the relationship Tov ≥ TgA,
The film (B) has a shrinkage ratio Xb of 0% or more and less than 4%, and the shrinkage ratio Xb is the width of the film (B) when the film (B) is treated under the conditions of a temperature Tov and 60 seconds. direction of shrinkage,
A method of manufacturing an optical film. The method of claim 1,
The said thermoplastic resin A contains an alicyclic structure containing polymer, The manufacturing method of an optical film. The method of claim 1,
The manufacturing method of the optical film which further includes the extending process of extending|stretching the said multilayer film in the in-plane direction. A polarizing plate provided with the optical film manufactured by the manufacturing method in any one of Claims 1-3, and a polarizer. The display device provided with the optical film manufactured by the manufacturing method in any one of Claims 1-3.

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