WO2018079745A1 - 広帯域波長フィルム及びその製造方法並びに円偏光フィルムの製造方法 - Google Patents
広帯域波長フィルム及びその製造方法並びに円偏光フィルムの製造方法 Download PDFInfo
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- WO2018079745A1 WO2018079745A1 PCT/JP2017/038998 JP2017038998W WO2018079745A1 WO 2018079745 A1 WO2018079745 A1 WO 2018079745A1 JP 2017038998 W JP2017038998 W JP 2017038998W WO 2018079745 A1 WO2018079745 A1 WO 2018079745A1
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
- G02B5/3025—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state
- G02B5/3033—Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state in the form of a thin sheet or foil, e.g. Polaroid
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
- B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
- B29C48/07—Flat, e.g. panels
- B29C48/08—Flat, e.g. panels flexible, e.g. films
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
- B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
- B29C55/04—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
- B29D11/00—Producing optical elements, e.g. lenses or prisms
- B29D11/00634—Production of filters
- B29D11/00644—Production of filters polarizing
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29D—PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE
- B29D11/00—Producing optical elements, e.g. lenses or prisms
- B29D11/0074—Production of other optical elements not provided for in B29D11/00009- B29D11/0073
- B29D11/00788—Producing optical films
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
- B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
- B32B27/22—Layered products comprising a layer of synthetic resin characterised by the use of special additives using plasticisers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
- B32B27/302—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising aromatic vinyl (co)polymers, e.g. styrenic (co)polymers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
- B32B7/02—Physical, chemical or physicochemical properties
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
- B32B7/02—Physical, chemical or physicochemical properties
- B32B7/023—Optical properties
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
- B32B7/03—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers with respect to the orientation of features
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/30—Polarising elements
- G02B5/3083—Birefringent or phase retarding elements
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2001/00—Use of cellulose, modified cellulose or cellulose derivatives, e.g. viscose, as moulding material
- B29K2001/08—Cellulose derivatives
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
- B29K2025/00—Use of polymers of vinyl-aromatic compounds or derivatives thereof as moulding material
- B29K2025/04—Polymers of styrene
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B38/00—Ancillary operations in connection with laminating processes
- B32B38/0012—Mechanical treatment, e.g. roughening, deforming, stretching
- B32B2038/0028—Stretching, elongating
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/40—Properties of the layers or laminate having particular optical properties
- B32B2307/42—Polarizing, birefringent, filtering
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2307/00—Properties of the layers or laminate
- B32B2307/50—Properties of the layers or laminate having particular mechanical properties
- B32B2307/514—Oriented
Definitions
- the present invention relates to a broadband wavelength film, a method for producing the same, and a method for producing a circularly polarizing film.
- a film including a combination of a ⁇ / 2 plate and a ⁇ / 4 plate is known.
- a broadband wavelength film includes a step of stretching a film to obtain a ⁇ / 2 plate, a step of stretching another film to obtain a ⁇ / 4 plate, and the ⁇ / 2 plate and ⁇ / plate. It is common to manufacture by the manufacturing method including the process of bonding 4 plates and obtaining a broadband wavelength film.
- a technique for obtaining a circularly polarizing film by combining the broadband wavelength film with a linearly polarizing film as a film that can function as a linearly polarizing plate is known.
- a long linearly polarizing film has an absorption axis in the longitudinal direction or the width direction.
- the slow axis of the ⁇ / 2 plate is required to be in an oblique direction that is neither parallel nor perpendicular to the width direction. .
- the present invention was devised in view of the above problems, and a broadband wavelength film that can be efficiently manufactured with a small number of steps and a method for manufacturing the same; and a method for manufacturing a circularly polarizing film including the method for manufacturing the broadband wavelength film
- the purpose is to provide;
- the present inventor has prepared a first step of preparing a layer (A) as a long obliquely stretched film; on this layer (A), the intrinsic birefringence is negative.
- the present inventors have found that the problems can be solved and completed the present invention. That is, the present invention includes the following.
- [3] The method for producing a broadband wavelength film according to [1] or [2], wherein the ⁇ / 4 layer has a slow axis that forms an angle of 0 ° ⁇ 20 ° with respect to the width direction of the broadband wavelength film. .
- [4] Any one of [1] to [3], wherein the layer (A) has a slow axis that forms an angle greater than 15 ° and less than 50 ° with respect to the width direction of the layer (A).
- [5] The method according to any one of [1] to [4], wherein the second step includes coating the layer (A) with a composition containing a resin having a negative intrinsic birefringence.
- a method for producing the described broadband wavelength film [6] The broadband wavelength film according to any one of [1] to [4], wherein the second step includes extruding a resin having a negative intrinsic birefringence onto the layer (A). Production method. [7] The broadband according to any one of [1] to [4], wherein the second step includes bonding a film of a resin having a negative intrinsic birefringence to the layer (A). A method for producing a wavelength film. [8] The third step includes stretching the multilayer film in a stretching direction that forms an angle of 90 ° ⁇ 20 ° with respect to the width direction of the multilayer film. The manufacturing method of the broadband wavelength film as described in any one of these.
- the long broadband wavelength film according to [13], comprising a thin film layer having a thickness of less than 2 ⁇ m between the ⁇ / 2 layer and the ⁇ / 4 layer.
- the amount of the plasticizer in the ⁇ / 4 layer is 0.001 wt% or more and 20 wt% or less.
- the method for producing a broadband wavelength film of the present invention since the number of stretching can be reduced as compared with the conventional method, the production of the broadband wavelength film can be efficiently performed with a small number of steps.
- the broadband wavelength film of the present invention can be efficiently produced with a smaller number of processes than in the past.
- the method for producing a circularly polarizing film of the present invention since a broadband wavelength film can be efficiently produced with a small number of steps, the circularly polarizing film can also be produced efficiently.
- FIG. 1 is a perspective view schematically showing a layer (A) as a long diagonally stretched film prepared in the first step of the method for producing a broadband wavelength film according to one embodiment of the present invention.
- FIG. 2 is a perspective view schematically showing a multilayer film obtained in the second step of the method for producing a broadband wavelength film according to one embodiment of the present invention.
- FIG. 3 is a perspective view schematically showing a broadband wavelength film obtained in the third step of the method for manufacturing a broadband wavelength film according to an embodiment of the present invention.
- the “long” film means a film having a length of 5 times or more, preferably 10 times or more, and specifically a roll.
- the upper limit of the film length is not particularly limited, and can be, for example, 100,000 times or less with respect to the width.
- the NZ coefficient of the layer is a value represented by (nx ⁇ nz) / (nx ⁇ ny) unless otherwise specified.
- nx represents a refractive index in a direction (in-plane direction) perpendicular to the thickness direction of the layer and giving the maximum refractive index.
- ny represents the refractive index in the in-plane direction of the layer and perpendicular to the nx direction.
- nz represents the refractive index in the thickness direction of the layer.
- d represents the thickness of the layer. The measurement wavelength is 590 nm unless otherwise specified.
- a material having a positive intrinsic birefringence means a material in which the refractive index in the stretching direction is larger than the refractive index in the direction perpendicular thereto unless otherwise specified.
- a material having a negative intrinsic birefringence means a material in which the refractive index in the stretching direction is smaller than the refractive index in the direction perpendicular thereto unless otherwise specified.
- the value of intrinsic birefringence can be calculated from the dielectric constant distribution.
- (meth) acryl includes “acryl”, “methacryl”, and combinations thereof.
- the slanting direction of the long film indicates the in-plane direction of the film, which is neither parallel nor perpendicular to the width direction of the film.
- the front direction of a film means the normal direction of the main surface of the film, specifically, the direction of the polar angle 0 ° and the azimuth angle 0 ° of the main surface. Point to.
- the inclination direction of a film means a direction that is neither parallel nor perpendicular to the main surface of the film, and specifically, the polar angle of the main surface is larger than 0 ° and 90 °. Point in a direction smaller than °.
- the directions of the elements “parallel”, “vertical”, and “orthogonal” include errors within a range that does not impair the effects of the present invention, for example, ⁇ 5 °, unless otherwise specified. You may go out.
- the angle formed by the optical axis (absorption axis, slow axis, etc.) of each layer in a member having a plurality of layers represents the angle when the layer is viewed from the thickness direction unless otherwise specified.
- the slow axis of the film or layer represents the slow axis in the plane of the film or layer.
- the orientation angle of the film or layer represents an angle formed by the slow axis of the film or layer with respect to the width direction of the film or layer.
- FIG. 1 is a perspective view schematically showing a layer (A) 100 as a long obliquely stretched film prepared in the first step of the method for producing a broadband wavelength film according to an embodiment of the present invention.
- FIG. 2 is a perspective view schematically showing a multilayer film 200 obtained in the second step of the method for producing a broadband wavelength film according to an embodiment of the present invention.
- FIG. 3 is a perspective view schematically showing a broadband wavelength film 300 obtained in the third step of the method for manufacturing a broadband wavelength film according to an embodiment of the present invention.
- the method for manufacturing the broadband wavelength film 300 includes: (1) As shown in FIG. 1, a first step of preparing a layer (A) 100 as a long obliquely stretched film; (2) a second step of forming a resin layer (B) 210 having a negative intrinsic birefringence on the layer (A) 100 to obtain a multilayer film 200 shown in FIG. 2; (3) a third step of stretching the multilayer film 200 to obtain the long broadband wavelength film 300 shown in FIG. 3; Are included in this order.
- a layer which is prepared in the first step (A) 100, since there obliquely stretched film usually has a slow axis A 100 in the diagonal direction.
- the multilayer film 200 is stretched, as shown in FIG.
- the direction of the slow axis A 100 and the optical characteristics of the layer (A) 100 are adjusted.
- the slow axis A 210 usually appears in the layer (B), and optical characteristics are exhibited.
- the stretched layer (A) 100 functions as one of the ⁇ / 2 layer and the ⁇ / 4 layer
- the stretched layer (B) 210 functions as the other of the ⁇ / 2 layer and the ⁇ / 4 layer.
- a ⁇ / 2 layer and a ⁇ / 4 layer are obtained.
- the manufacturing method will be described in detail.
- a layer (A) as a long obliquely stretched film is prepared.
- this layer (A) an obliquely stretched film obtained by stretching a long resin film in an oblique direction of the resin film is usually used.
- said diagonally stretched film although the film of the multilayer structure containing two or more layers may be used, the film of the single layer structure containing only one layer is used normally.
- thermoplastic resin containing a polymer and further containing optional components as required can be used as the resin for forming the resin film.
- a resin having a negative intrinsic birefringence may be used as the resin contained in the layer (A).
- a resin having a positive intrinsic birefringence should be used because a broadband wavelength film can be manufactured particularly easily. Is preferred.
- the resin having a positive intrinsic birefringence usually contains a polymer having a positive intrinsic birefringence.
- polymers having a positive intrinsic birefringence include polyolefins such as polyethylene and polypropylene; polyesters such as polyethylene terephthalate and polybutylene terephthalate; polyarylene sulfides such as polyphenylene sulfide; polyvinyl alcohol; polycarbonate; polyarylate; Polysulfone; Polysulfone; Polyallyl sulfone; Polyvinyl chloride; Cyclic olefin polymer such as norbornene polymer; Rod-like liquid crystal polymer.
- polymers may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.
- the polymer may be a homopolymer or a copolymer.
- a polycarbonate polymer is preferable because it is excellent in expression of retardation and stretchability at low temperature, and because it is excellent in mechanical properties, heat resistance, transparency, low moisture absorption, dimensional stability and lightness. Cyclic olefin polymers are preferred.
- the proportion of the polymer in the resin contained in the layer (A) is preferably 50% by weight to 100% by weight, more preferably 70% by weight to 100% by weight, and particularly preferably 90% by weight to 100% by weight.
- the resin contained in the layer (A) may further contain any component other than the polymer in combination with the polymer.
- Optional components include, for example, colorants such as pigments and dyes; plasticizers; fluorescent brighteners; dispersants; thermal stabilizers; light stabilizers; ultraviolet absorbers; antistatic agents; Examples include activators. These components may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.
- the glass transition temperature TgA of the resin contained in the layer (A) is preferably 100 ° C. or higher, more preferably 110 ° C. or higher, particularly preferably 120 ° C. or higher, preferably 190 ° C. or lower, more preferably 180 ° C. or lower, Especially preferably, it is 170 degrees C or less.
- the layer (A) Since the layer (A) is an obliquely stretched film, it usually has a slow axis in the oblique direction.
- the orientation angle formed by the slow axis with respect to the width direction of the layer (A) can be arbitrarily set within a range in which a desired broadband wavelength film can be obtained.
- the orientation angle of the layer obtained by stretching the layer (A) in the third step is more than the orientation angle of the layer (A). Also grows. Therefore, in this case, the orientation angle of the layer (A) is preferably set to an angle smaller than the orientation angle of the layer obtained by stretching the layer (A) in the third step.
- the specific orientation angle of layer (A) is preferably greater than 15 °, more preferably greater than 17 °, particularly preferably greater than 20 °, and preferably less than 50 °, more preferably less than 49 °, Particularly preferably, it is less than 48 °.
- the orientation angle of the layer (A) is in the above range, a broadband wavelength film having preferred optical properties can be easily obtained by stretching the multilayer film in the preferred stretching direction described later in the third step.
- the optical properties such as retardation and NZ coefficient of the layer (A) can be set according to the optical properties of the layer obtained by stretching the layer (A).
- the in-plane retardation of the layer (A) is preferably 140 nm or more, more preferably 150 nm or more, and particularly preferably 160 nm or more.
- the thickness is preferably 250 nm or less, more preferably 240 nm or less, and particularly preferably 230 nm or less.
- the thickness of the layer (A) can be arbitrarily set within a range where a desired broadband wavelength film can be obtained.
- the specific thickness of the layer (A) is preferably 20 ⁇ m or more, more preferably 25 ⁇ m or more, particularly preferably 30 ⁇ m or more, preferably 100 ⁇ m or less, more preferably 95 ⁇ m or less, and particularly preferably 90 ⁇ m or less.
- a ⁇ / 2 layer or a ⁇ / 4 layer having desired optical properties can be easily obtained by stretching in the third step.
- the layer (A) can be manufactured by a manufacturing method including stretching a pre-stretching film as an appropriate long resin film in an oblique direction of the pre-stretching film.
- the film before stretching can be produced by, for example, a melt molding method or a solution casting method.
- the melt molding method include an extrusion molding method, a press molding method, an inflation molding method, an injection molding method, a blow molding method, and a stretch molding method.
- an extrusion molding method, an inflation molding method or a press molding method is preferable.
- the extrusion method is particularly preferred.
- the long unstretched film After preparing a long unstretched film, the long unstretched film can be stretched in an oblique direction to obtain a layer (A) as an obliquely stretched film.
- the stretch direction of the pre-stretched film is set according to the direction of the slow axis of the layer (A). It is preferable.
- the stretching direction of the film before stretching can be set in a direction parallel to the slow axis of the layer (A).
- the stretching direction of the film before stretching is set in a direction perpendicular to the slow axis of the layer (A). It is preferable.
- the stretching ratio in stretching for obtaining the layer (A) is preferably 1.1 times or more, more preferably 1.2 times or more, preferably 4.0 times or less, more preferably 3.0 times or less. is there.
- the refractive index in the stretching direction can be increased by setting the stretching ratio to be equal to or higher than the lower limit of the above range.
- stretching a layer (A) can be easily controlled by setting it as an upper limit or less.
- the stretching temperature in stretching for obtaining the layer (A) is preferably TgA ° C. or higher, more preferably “TgA + 2 ° C.” or higher, particularly preferably “TgA + 5 ° C.” or higher, preferably “TgA + 40 ° C.” or lower, more preferably Is “TgA + 35 ° C.” or less, particularly preferably “TgA + 30 ° C.” or less.
- TgA refers to the glass transition temperature of the resin contained in the layer (A).
- the stretching described above is usually performed using a tenter stretching machine while continuously transporting the film before stretching in the longitudinal direction.
- a tenter stretching machine for example, the one described in Patent Document 1 can be used.
- the method for producing a broadband wavelength film may include a step of forming a thin film layer on the layer (A), if necessary, after preparing the layer (A) in the first step.
- the thin film layer functions as an easy adhesion layer, and the binding force between the layer (A) and the layer (B) can be increased.
- the thin film layer is preferably solvent resistant.
- Such a thin film layer is usually formed of a resin.
- Examples of the material for the thin film layer include acrylic resin, urethane resin, acrylic urethane resin, ester resin, and ethyleneimine resin.
- the acrylic resin is a resin containing an acrylic polymer.
- the urethane resin is a resin containing polyurethane.
- a polymer such as an acrylic polymer and polyurethane usually has a high binding force for a wide variety of resins, so that the binding force between the layer (A) and the layer (B) can be increased.
- these polymers may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.
- Resin as a material of the thin film layer is combined with a polymer, heat stabilizer, weather stabilizer, leveling agent, antistatic agent, slip agent, antiblocking agent, antifogging agent, lubricant, dye, pigment, natural oil, Arbitrary components such as synthetic oil, wax, and particles may be included.
- Arbitrary components may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.
- the glass transition temperature of the resin as the material of the thin film layer is higher than the glass transition temperature TgA of the resin contained in the layer (A) and the glass transition temperature TgB of the resin having a negative intrinsic birefringence contained in the layer (B). Preferably it is low.
- the difference between the glass transition temperature of the resin as the material of the thin film layer and the lower one of the glass transition temperatures TgA and TgB is preferably 5 ° C. or higher, more preferably 10 ° C. or higher, and particularly preferably 20 ° C. or higher. preferable.
- the thin film layer in a broadband wavelength film can have optical isotropy. Therefore, it is possible to easily adjust the optical characteristics of the broadband wavelength film.
- the thin film layer can be formed, for example, by a method including coating a coating liquid containing a resin as a material for the thin film layer and a solvent on the layer (A).
- a solvent water or an organic solvent may be used.
- an organic solvent the thing similar to the solvent which can be used for formation of the layer (B) mentioned later is mentioned, for example.
- a solvent may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.
- the coating liquid may contain a crosslinking agent.
- a crosslinking agent By using a crosslinking agent, the mechanical strength of the thin film layer can be increased, and the binding property of the thin film layer to the layer (A) and the layer (B) can be increased.
- a crosslinking agent an epoxy compound, an amino compound, an isocyanate compound, a carbodiimide compound, an oxazoline compound, etc. can be used, for example. Moreover, these may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.
- the amount of the crosslinking agent is preferably 1 part by weight or more, more preferably 5 parts by weight or more, preferably 70 parts by weight or less, more preferably 65 parts by weight with respect to 100 parts by weight of the polymer in the coating liquid. It is as follows.
- Examples of the coating method of the coating liquid include the same methods as the coating method that can be used for forming the layer (B) described later.
- a thin film layer can be formed by applying a coating solution on the layer (A).
- This thin film layer may be subjected to a curing treatment such as drying and crosslinking as necessary.
- a curing treatment such as drying and crosslinking as necessary.
- the drying method include heat drying using an oven.
- crosslinking method methods, such as heat processing, irradiation processing of active energy rays, such as an ultraviolet-ray, are mentioned, for example.
- Second step In the first step, after preparing the layer (A) and forming a thin film layer as necessary, the second step of forming a resin layer (B) having a negative intrinsic birefringence to obtain a multilayer film Do.
- the layer (B) is formed directly on the layer (A) or indirectly via an arbitrary layer such as a thin film layer.
- “directly” means that there is no arbitrary layer between the layer (A) and the layer (B).
- the resin having a negative intrinsic birefringence is usually a thermoplastic resin and includes a polymer having a negative intrinsic birefringence.
- polymers having a negative intrinsic birefringence include styrene or a styrene derivative homopolymer, and a polystyrene-based polymer including a copolymer of styrene or a styrene derivative and an arbitrary monomer; a polyacrylonitrile polymer; Examples thereof include polymethyl methacrylate polymers; multi-component copolymers thereof; and cellulose compounds such as cellulose esters.
- arbitrary monomer which can be copolymerized with styrene or a styrene derivative acrylonitrile, maleic anhydride, methyl methacrylate, and butadiene are mentioned as a preferable thing, for example.
- polystyrene polymers and cellulose compounds are preferred.
- these polymers may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.
- the ratio of the polymer in the resin having a negative intrinsic birefringence is preferably 50% by weight to 100% by weight, more preferably 70% by weight to 100% by weight, and particularly preferably 90% by weight to 100% by weight.
- the resin having a negative intrinsic birefringence contained in the layer (B) preferably contains a plasticizer.
- a plasticizer By using a plasticizer, the glass transition temperature TgB of the resin contained in the layer (B) can be adjusted appropriately.
- the plasticizer include phthalate esters, fatty acid esters, phosphate esters, and epoxy derivatives. Specific examples of the plasticizer include those described in JP-A-2007-233114.
- a plasticizer may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.
- phosphate esters are preferable because they are easily available and inexpensive.
- phosphate esters include trialkyl phosphates such as triethyl phosphate, tributyl phosphate and trioctyl phosphate; halogen-containing trialkyl phosphates such as trichloroethyl phosphate; triphenyl phosphate and tricresyl Triaryl phosphates such as phosphate, tris (isopropylphenyl) phosphate, cresyl diphenyl phosphate; alkyl-diaryl phosphates such as octyl diphenyl phosphate; tri (alkoxy) such as tri (butoxyethyl) phosphate Alkyl) phosphate; and the like.
- the amount of the plasticizer is preferably 0.001% by weight or more, more preferably 0.005% by weight or more, particularly preferably 100% by weight of the amount of the resin having a negative intrinsic birefringence contained in the layer (B). Is 0.1% by weight or more, preferably 20% by weight or less, more preferably 18% by weight or less, and particularly preferably 15% by weight or less. Since the glass transition temperature TgB of the resin contained in the layer (B) can be appropriately adjusted by keeping the amount of the plasticizer within the above range, appropriate stretching for obtaining a desired broadband wavelength film is performed in the third step. It is possible.
- the resin having a negative intrinsic birefringence may further contain an optional component other than the polymer and the plasticizer in combination with the polymer and the plasticizer.
- an optional component the same example as the arbitrary component which the resin contained in a layer (A) can contain is mentioned, for example.
- Arbitrary components may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.
- the glass transition temperature TgB of the resin having a negative intrinsic birefringence contained in the layer (B) is preferably 80 ° C. or higher, more preferably 90 ° C. or higher, further preferably 100 ° C. or higher, and particularly preferably 110 ° C. or higher, particularly preferably. Is 120 ° C. or higher. Since the glass transition temperature TgB of the resin having a negative intrinsic birefringence is thus high, the relaxation of the orientation of the resin having a negative intrinsic birefringence can be reduced. Moreover, although there is no restriction
- the glass transition temperature TgA of the resin contained in the layer (A) and the layer (B) It is preferable that it is not excessively separated from the glass transition temperature TgB of the resin having a negative intrinsic birefringence.
- of the difference between the glass transition temperature TgA and the glass transition temperature TgB is preferably 20 ° C. or less, more preferably 15 ° C. or less, and particularly preferably 10 ° C. or less.
- the layer (B) may have in-plane retardation and a slow axis.
- the in-plane retardation and the slow axis of the layer (B) are adjusted by stretching in the third step.
- the setting of the stretching conditions for performing such adjustment tends to be complicated. Therefore, from the viewpoint of easily obtaining the desired optical characteristics and slow axis direction in the layer (B) after stretching in the third step, the layer (B) formed in the second step has in-plane retardation and slow phase. It is preferable that the in-plane retardation is small even if it does not have an axis.
- the in-plane retardation of the layer (B) is preferably 0 nm to 20 nm, more preferably 0 nm to 15 nm, and particularly preferably 0 nm to 10 nm.
- the thickness of the layer (B) can be arbitrarily set within a range where a desired broadband wavelength film can be obtained.
- the specific thickness of the layer (B) is preferably 3 ⁇ m or more, more preferably 4 ⁇ m or more, particularly preferably 5 ⁇ m or more, preferably 15 ⁇ m or less, more preferably 13 ⁇ m or less, and particularly preferably 11 ⁇ m or less.
- a ⁇ / 2 layer or a ⁇ / 4 layer having desired optical properties can be easily obtained by stretching.
- a layer (B) There is no special restriction
- formation methods such as a coating method, an extrusion method, and the bonding method, can be used.
- the second step includes coating a composition containing a resin having a negative intrinsic birefringence on the layer (A).
- the above composition is usually a liquid composition containing a solvent in combination with a resin having a negative intrinsic birefringence.
- the solvent examples include methyl acetate, ethyl acetate, acetone, methyl ethyl ketone, 3-methyl-2-butanone, methyl isobutyl ketone, tetrahydrofuran, cyclopentyl methyl ether, acetylacetone, cyclohexanone, 2-methylcyclohexanone, 1,3-dioxolane, 1 , 4-dioxane, 2-pentanone, N, N-dimethylformamide and the like.
- a solvent may be used individually by 1 type and may be used combining two or more types by arbitrary ratios.
- Examples of the coating method of the composition include curtain coating method, extrusion coating method, roll coating method, spin coating method, dip coating method, bar coating method, spray coating method, slide coating method, print coating method, and gravure.
- Examples of the method include a coating method, a die coating method, a gap coating method, and a dipping method.
- the second step includes drying the coated composition as necessary after coating the composition on the layer (A).
- a resin layer (B) having a negative intrinsic birefringence can be formed on the layer (A). Drying can be performed by a drying method such as natural drying, heat drying, reduced pressure drying, and reduced pressure heat drying.
- the second step includes extruding a resin having a negative intrinsic birefringence on the layer (A).
- the extrusion of the resin is usually performed in a state where the resin is melted.
- resin is normally extruded to a film form using die
- a resin (B) having a negative intrinsic birefringence may be formed on the layer (A) by adhering the extruded resin having a negative intrinsic birefringence to the layer (A) or the thin film layer. it can.
- the second step usually includes cooling and curing the resin having a negative intrinsic birefringence that has been extruded and attached to the layer (A).
- a 2nd process includes bonding the film of resin with a negative intrinsic birefringence to a layer (A).
- the method for producing a resin film having a negative intrinsic birefringence include melt molding methods such as an extrusion molding method, an inflation molding method, and a press molding method; and a solution casting method.
- the coating method is preferable.
- a resin having a negative intrinsic birefringence tends to have a low mechanical strength.
- the layer (B) can be easily formed while using a resin having low mechanical strength.
- a bonding method forming a layer (B) on an appropriate support film, and bonding this layer (B) to the layer (A), while suppressing damage to the layer (B) It is possible to form the layer (B) on the layer (A).
- the coating method is the layer (B).
- the number of steps required to form the film can be reduced.
- an adhesive and a pressure-sensitive adhesive are unnecessary.
- the thickness of the layer (B) itself can be made thinner than in the extrusion method. Therefore, from the viewpoint of obtaining a thin broadband wavelength film with a small number of steps, it is preferable to form the layer (B) by a coating method.
- the third step of stretching the multilayer film to obtain a long broadband wavelength film is performed.
- the direction of the slow axis of the layer (A) is adjusted, and the optical characteristics of the layer (A) are adjusted to obtain one of the ⁇ / 2 layer and the ⁇ / 4 layer.
- the slow axis appears in the layer (B), and the optical characteristics appear in the layer (B), and the other of the ⁇ / 2 layer and the ⁇ / 4 layer is obtained.
- the stretching in the third step is usually performed only in one direction.
- the stretching direction in the third step is preferably set so that a desired broadband wavelength film can be obtained.
- the direction of the slow axis of the layer (A) changes so as to approach the stretching direction by stretching in the third step.
- the layer (A) is a resin layer having a negative intrinsic birefringence
- the slow axis direction of the layer (A) is perpendicular to the stretching direction by stretching in the third step. It changes to approach the direction.
- the direction of the slow axis of a layer (A) changes with extending
- a slow axis appears in a direction perpendicular to the stretching direction by stretching in the third step.
- the stretching direction in the third step is delayed in the desired direction by the change in the direction of the slow axis in the layer (A) and the development of the slow axis in the layer (B). It is preferable to set so that ⁇ / 2 layers and ⁇ / 4 layers having axes are obtained.
- the third step preferably includes stretching the multilayer film in a stretching direction that forms an angle of 90 ° ⁇ 20 ° with respect to the width direction of the multilayer film. More specifically, the angle formed by the stretching direction in the third step with respect to the width direction of the multilayer film is preferably 90 ° ⁇ 20 °, more preferably 90 ° ⁇ 15 °, still more preferably 90 ° ⁇ 10. It is in the range of °.
- the stretching in the third step is preferably performed in the longitudinal direction of the multilayer film forming an angle of 90 ° with respect to the width direction of the multilayer film. By stretching in such a stretching direction, the direction of the slow axis can be easily controlled.
- the draw ratio in the third step is preferably 1.1 times or more, more preferably 1.15 times or more, particularly preferably 1.2 times or more, preferably 2.0 times or less, more preferably 1.8 times. It is not more than twice, particularly preferably not more than 1.6 times.
- the stretching temperature in the third step is the following condition (C1) with respect to the glass transition temperature TgA of the resin contained in the layer (A) and the glass transition temperature TgB of the resin having a negative intrinsic birefringence contained in the layer (B). ) And (C2) are preferably satisfied.
- the stretching temperature is preferably TgA-20 ° C or higher, more preferably TgA-10 ° C or higher, particularly preferably TgA-5 ° C or higher, preferably TgA + 30 ° C or lower, more preferably TgA + 25 ° C or lower, particularly preferably. Is a temperature of TgA + 20 ° C. or lower.
- the stretching temperature is preferably TgB-20 ° C or higher, more preferably TgB-10 ° C or higher, particularly preferably TgB-5 ° C or higher, preferably TgB + 30 ° C or lower, more preferably TgB + 25 ° C or lower, particularly preferably. Is a temperature of TgB + 20 ° C. or lower.
- the stretching in the third step is preferably performed by free uniaxial stretching.
- free uniaxial stretching refers to stretching in a certain direction, and does not apply a restraining force in a direction other than the stretched direction.
- free uniaxial stretching in the longitudinal direction of a multilayer film refers to stretching in the longitudinal direction without restraining the widthwise end of the multilayer film.
- the stretching in the third step described above can be performed using an arbitrary stretching machine, for example, a tenter stretching machine or a roll stretching machine.
- a roll stretching machine free uniaxial stretching can be easily performed. Free uniaxial stretching using a roll stretching machine is usually performed while continuously transporting a long multilayer film in the longitudinal direction.
- the roll stretching machine for example, the one described in Patent Document 1 can be used.
- a long broadband wavelength film can be obtained as a co-stretched film having a ⁇ / 2 layer and a ⁇ / 4 layer.
- the stretching of the layer (A) and the layer (B) is not performed separately as in the prior art, but is performed together in the third step. Therefore, since the number of stretching processes can be reduced as compared with the prior art, the number of steps required for producing a broadband wavelength film can be reduced, and thus efficient production can be realized.
- both the ⁇ / 2 layer and the ⁇ / 4 layer are produced after the production.
- the conventional manufacturing method of bonding there is no shift in the slow axis direction due to bonding. Therefore, since it is easy to precisely control the direction of the slow axis of each of the ⁇ / 2 layer and the ⁇ / 4 layer, a high-quality broadband wavelength film capable of realizing a circularly polarizing film capable of effectively suppressing coloring. Can be easily obtained.
- the ⁇ / 2 layer is a layer obtained by stretching one of the layer (A) and the layer (B), and the ⁇ / 4 layer is the layer (A) and the layer (B ) Is a layer obtained by stretching.
- the ⁇ / 2 layer is preferably a layer obtained by stretching the layer (A)
- the ⁇ / 4 layer is preferably a layer (B ) Is preferably obtained by stretching. Therefore, the ⁇ / 2 layer is preferably a layer made of the same resin as the layer (A), and the ⁇ / 4 layer is preferably a layer made of the same resin as the layer (B).
- the ⁇ / 2 layer is a layer having in-plane retardation of usually 240 nm or more and usually 300 nm or less at a measurement wavelength of 590 nm. Since the ⁇ / 2 layer has such in-plane retardation, a broadband wavelength film can be realized by combining the ⁇ / 2 layer and the ⁇ / 4 layer. Therefore, by combining this broadband wavelength film with a linearly polarizing film, a broadband circular polarizing film having a function of absorbing one of right circularly polarized light and left circularly polarized light and transmitting the remaining light in a wide wavelength range. realizable.
- this circularly polarizing film can suppress coloring of the display surface due to an increase in reflection intensity of light having some wavelengths.
- the in-plane retardation of the ⁇ / 2 layer at a measurement wavelength of 590 nm is preferably 250 nm or more, preferably 280 nm or less, more preferably Is 265 nm or less.
- the retardation in the thickness direction of the ⁇ / 2 layer at a measurement wavelength of 590 nm is preferably 120 nm or more, more preferably 125 nm or more, particularly preferably 130 nm or more, preferably 240 nm or less, more preferably 230 nm or less, particularly preferably 220 nm. It is as follows. When the retardation in the thickness direction of the ⁇ / 2 layer is in the above range, the function of suppressing coloring in the tilt direction by the circularly polarizing film can be further enhanced.
- the NZ coefficient of the ⁇ / 2 layer is preferably 1.0 or more, more preferably 1.05 or more, preferably 1.3 or less, more preferably 1.25 or less, and particularly preferably 1.20 or less. .
- the NZ coefficient of the ⁇ / 2 layer is in the above range, the function of suppressing coloring in the tilt direction by the circularly polarizing film can be further enhanced. Further, the ⁇ / 2 layer having such an NZ coefficient can be easily manufactured.
- the optical properties such as the retardation of the ⁇ / 2 layer and the NZ coefficient include, for example, the retardation and thickness of the layer (A) prepared in the first step; and the stretching temperature, stretching ratio, stretching direction, etc. in the third step.
- the stretching conditions can be adjusted.
- the ⁇ / 2 layer has a slow axis in a direction corresponding to the slow axis direction of the ⁇ / 4 layer. It is preferable.
- a ⁇ / 4 layer having a slow axis that forms an angle ⁇ ( ⁇ / 4) with respect to a certain reference direction (for example, the longitudinal direction of the film), and an angle ⁇ ( ⁇ / 2) with respect to the reference direction.
- a broadband wavelength film capable of giving in-plane retardation of approximately 1 ⁇ 4 wavelength of the wavelength of the light transmitted through the light (see Japanese Patent Application Laid-Open No. 2007-004120). Therefore, in the broadband wavelength film, it is preferable that the slow axis of the ⁇ / 2 layer satisfies a relationship close to the slow axis of the ⁇ / 4 layer as expressed in the above formula X.
- the angle formed by the slow axis of the ⁇ / 2 layer and the slow axis of the ⁇ / 4 layer is preferably 67.5 ° ⁇ 10 °, more preferably 67.5 ° ⁇ 5 °, particularly The angle is preferably 67.5 ° ⁇ 3 °.
- a general linearly polarizing film has a transmission axis in the width direction and an absorption axis in the longitudinal direction.
- the orientation angle formed by the slow axis of the ⁇ / 2 layer with respect to the width direction of the broadband wavelength film is: The angle is preferably 67.5 ° ⁇ 10 °, more preferably 67.5 ° ⁇ 5 °, and particularly preferably 67.5 ° ⁇ 3 °.
- the direction of the slow axis of the ⁇ / 2 layer is, for example, the direction of the slow axis of the layer (A) prepared in the first step; and the stretching conditions such as the stretching direction and the stretching ratio in the third step; Can be adjusted.
- the thickness of the ⁇ / 2 layer is preferably 20 ⁇ m or more, more preferably 25 ⁇ m or more, further preferably 30 ⁇ m or more, preferably 80 ⁇ m or less, more preferably 70 ⁇ m or less, and even more preferably 60 ⁇ m or less. Thereby, the mechanical strength of the ⁇ / 2 layer can be increased.
- the ⁇ / 4 layer is a layer having an in-plane retardation of usually 110 nm or more and usually 154 nm or less at a measurement wavelength of 590 nm. Since the ⁇ / 4 layer has such in-plane retardation, a broadband wavelength film can be realized by combining the ⁇ / 2 layer and the ⁇ / 4 layer. Therefore, a broadband circularly polarizing film can be realized by combining this broadband wavelength film with a linearly polarizing film. By providing this circularly polarizing film in the image display device, it is possible to reduce the reflection of light in a wide wavelength range in both the front direction and the tilt direction, and to suppress coloring of the display surface. Is possible.
- the in-plane retardation of the ⁇ / 4 layer at a measurement wavelength of 590 nm is preferably 118 nm or more, preferably 138 nm or less, more preferably Is 128 nm or less.
- the retardation in the thickness direction of the ⁇ / 4 layer at a measurement wavelength of 590 nm is preferably 100 nm or more, more preferably 110 nm or more, particularly preferably 120 nm or more, preferably 180 nm or less, more preferably 170 nm or less, particularly preferably 160 nm. It is as follows. When the retardation in the thickness direction of the ⁇ / 4 layer is within the above range, the function of suppressing coloring in the tilt direction by the circularly polarizing film can be further enhanced.
- the NZ coefficient of the ⁇ / 4 layer is preferably ⁇ 1.0 or more, more preferably ⁇ 0.6 or more, particularly preferably ⁇ 0.4 or more, preferably 0.5 or less, more preferably 0.3. Hereinafter, it is more preferably 0.1 or less, particularly preferably 0.0 or less. In particular, the NZ coefficient of the ⁇ / 4 layer is particularly preferably ⁇ 0.2 ⁇ 0.2. When the NZ coefficient of the ⁇ / 4 layer is in the above range, the function of suppressing coloring in the tilt direction by the circularly polarizing film can be further enhanced. In addition, the ⁇ / 4 layer having such an NZ coefficient can be easily manufactured.
- optical properties such as retardation and NZ coefficient of the ⁇ / 4 layer are, for example, the thickness of the layer (B) formed in the second step; and the stretching conditions such as the stretching temperature, the stretching ratio and the stretching direction in the third step Can be adjusted.
- the ⁇ / 4 layer usually has a slow axis developed in a direction perpendicular to the stretching direction in the third step by stretching in the third step.
- the orientation angle formed by the slow axis of the ⁇ / 4 layer with respect to the width direction of the broadband wavelength film is preferably 0 ° ⁇ 20 °, more preferably 0 ° ⁇ 10 °, particularly preferably 0 ° ⁇ . 5 °.
- a broadband wavelength film including a ⁇ / 4 layer having such a slow axis realizes a circularly polarizing film in combination with a general linearly polarizing film having a transmission axis in the width direction and an absorption axis in the longitudinal direction. it can.
- the direction of the slow axis of the ⁇ / 4 layer can be adjusted by, for example, the stretching direction in the third step.
- the thickness of the ⁇ / 4 layer is preferably 3 ⁇ m or more, more preferably 4 ⁇ m or more, particularly preferably 5 ⁇ m or more, preferably 15 ⁇ m or less, more preferably 13 ⁇ m or less, and particularly preferably 10 ⁇ m or less.
- the ⁇ / 2 layer and the ⁇ / 4 layer are preferably in direct contact with each other. Thereby, the thickness of the broadband wavelength film can be reduced.
- the broadband wavelength film includes a thin film layer between the ⁇ / 2 layer and the ⁇ / 4 layer.
- the thin film layer of the broadband wavelength film obtained by the manufacturing method described above is thicker than the adhesive layer used in the conventional manufacturing method in which the ⁇ / 2 layer and the ⁇ / 4 layer are bonded together after manufacturing each of the ⁇ / 2 layer and the ⁇ / 4 layer. Can be thinner than that.
- the specific thickness of the thin film layer is preferably less than 2.0 ⁇ m, more preferably less than 1.8 ⁇ m, and particularly preferably less than 1.5 ⁇ m.
- the lower limit of the thickness of the thin film layer is preferably as thin as possible, and may be, for example, 0.1 ⁇ m.
- the broadband wavelength film may include an arbitrary layer in combination with the ⁇ / 2 layer, the ⁇ / 4 layer, and the thin film layer.
- an adhesive layer or an adhesive layer for adhering the ⁇ / 2 layer and the ⁇ / 4 layer may be provided.
- the total light transmittance of the broadband wavelength film is preferably 80% or more, more preferably 85% or more, and particularly preferably 88% or more.
- the light transmittance can be measured in a wavelength range of 400 nm to 700 nm using a spectrophotometer according to JIS K0115.
- the haze of the broadband wavelength film is preferably 5% or less, more preferably 3% or less, particularly preferably 1% or less, and ideally 0%.
- the haze can be measured at five locations using “turbidity meter NDH-300A” manufactured by Nippon Denshoku Industries Co., Ltd. in accordance with JIS K7361-1997, and the average value obtained therefrom can be adopted.
- the thickness of the broadband wavelength film is preferably 30 ⁇ m or more, more preferably 35 ⁇ m or more, particularly preferably 40 ⁇ m or more, preferably 100 ⁇ m or less, more preferably 90 ⁇ m or less, and particularly preferably 80 ⁇ m or less. According to the manufacturing method described above, it is possible to easily manufacture such a thin broadband wavelength film.
- the manufacturing method of the broadband wavelength film described above may further include an optional step in combination with the first step, the second step, and the third step.
- the method for producing a broadband wavelength film may include a step of providing a protective layer on the surface of the broadband wavelength film.
- surface treatment such as corona treatment and plasma treatment is applied to one or more surfaces of the layer (A), the layer (B), and the thin film layer at an arbitrary time.
- the process to apply may be included. Therefore, for example, after the surface treatment is performed on the surface of the layer (A), the layer (B) or the thin film layer may be formed on the treated surface. Further, for example, after the surface treatment is performed on the surface of the thin film layer, the layer (B) may be formed on the treated surface.
- the surface treatment it is possible to enhance the binding property between the layers on the surface-treated surface.
- a long circularly polarizing film can be manufactured using the broadband wavelength film manufactured by the manufacturing method described above.
- Such a circularly polarizing film can be manufactured by a manufacturing method including a step of manufacturing a broadband wavelength film by the above-described manufacturing method and a step of bonding the broadband wavelength film and a long linear polarizing film. The bonding is performed so that the linearly polarizing film, the ⁇ / 2 layer, and the ⁇ / 4 layer are arranged in this order in the thickness direction.
- the linearly polarizing film is a long film having an absorption axis, and has a function of absorbing linearly polarized light having a vibration direction parallel to the absorption axis and transmitting other polarized light.
- the vibration direction of linearly polarized light means the vibration direction of the electric field of linearly polarized light.
- the linearly polarizing film usually includes a polarizer layer, and a protective film layer for protecting the polarizer layer as necessary.
- a polarizer layer for example, a film obtained by subjecting a suitable vinyl alcohol polymer film to appropriate treatment in an appropriate order and manner can be used.
- vinyl alcohol polymers include polyvinyl alcohol and partially formalized polyvinyl alcohol.
- the film treatment include dyeing treatment with dichroic substances such as iodine and dichroic dyes, stretching treatment, and crosslinking treatment.
- the stretching treatment for producing the polarizer layer the film before stretching is stretched in the longitudinal direction, and therefore the obtained polarizer layer can exhibit an absorption axis parallel to the longitudinal direction of the polarizer layer.
- This polarizer layer is capable of absorbing linearly polarized light having a vibration direction parallel to the absorption axis, and is particularly preferably excellent in polarization degree.
- the thickness of the polarizer layer is generally 5 ⁇ m to 80 ⁇ m, but is not limited thereto.
- any transparent film can be used as the protective film layer for protecting the polarizer layer.
- a resin film excellent in transparency, mechanical strength, thermal stability, moisture shielding properties and the like is preferable.
- resins include acetate resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, cyclic olefin resins, (meth) acrylic resins, and the like.
- acetate resin, cyclic olefin resin, and (meth) acrylic resin are preferable in terms of low birefringence, and cyclic olefin resin is particularly preferable from the viewpoint of transparency, low moisture absorption, dimensional stability, lightness, and the like.
- the linearly polarizing film can be manufactured, for example, by laminating a long polarizer layer and a long protective film layer. In bonding, an adhesive may be used as necessary.
- the linearly polarizing film preferably has an absorption axis in the longitudinal direction of the linearly polarizing film.
- a linearly polarizing film is laminated with a broadband wavelength film comprising a ⁇ / 2 layer having an orientation angle of 67.5 ° ⁇ 10 ° and a ⁇ / 4 layer having an orientation angle of 0 ° ⁇ 20 °, It is preferable to produce a circularly polarizing film.
- a broadband wavelength film comprising a ⁇ / 2 layer having an orientation angle of 67.5 ° ⁇ 10 ° and a ⁇ / 4 layer having an orientation angle of 0 ° ⁇ 20 °.
- the circularly polarizing film In the circularly polarizing film thus obtained, linearly polarized light in a wide wavelength range transmitted through the linearly polarizing film is converted into circularly polarized light by the broadband wavelength film. Therefore, the circularly polarizing film has a function of absorbing one of right circularly polarized light and left circularly polarized light and transmitting the remaining light in a wide wavelength range.
- the circularly polarizing film may further include an arbitrary layer in combination with the linearly polarizing film and the broadband wavelength film.
- the circularly polarizing film may include a protective film layer for suppressing damage.
- the circularly polarizing film may include an adhesive layer or an adhesive layer for adhesion between the linearly polarizing film and the broadband wavelength film.
- the circularly polarizing film When the circularly polarizing film is provided on a surface that can reflect light, reflection of external light can be effectively reduced.
- the circularly polarizing film is useful in that reflection of external light can be effectively reduced in a wide wavelength range in the visible region. And since reflection of external light can be effectively reduced in such a wide wavelength range, the circularly polarizing film can suppress coloring due to an increase in the reflection intensity of light of some wavelengths.
- the circularly polarizing film can obtain the effects of suppressing reflection and coloring in both the front direction and the tilt direction, and can usually be obtained in all azimuthal directions of the film main surface. .
- the circularly polarizing film can be used as a reflection suppressing film of an organic electroluminescence display device (hereinafter sometimes referred to as “organic EL display device” as appropriate).
- the organic EL display device includes a circularly polarizing film piece obtained by cutting out from a long circularly polarizing film.
- the organic EL display device usually includes a circularly polarizing film piece on the display surface.
- the circularly polarizing film may be provided in a liquid crystal display device.
- a liquid crystal display device includes a circularly polarizing film piece obtained by cutting out from a long circularly polarizing film.
- the liquid crystal display device includes a circularly polarizing film piece so that the surface on the linearly polarizing film side faces the viewing side, it is possible to prevent light incident from the outside of the device from being reflected inside the device and emitted to the outside of the device. As a result, glare and coloring of the display surface of the display device can be suppressed.
- the broadband wavelength film of this circularly polarizing film piece is closer to the display surface than the liquid crystal cell of the liquid crystal display device When in position, the image can be displayed with circular polarization. Therefore, it is possible to stably view the light emitted from the display surface with the polarized sunglasses, and the image visibility when wearing the polarized sunglasses can be enhanced.
- an image display device includes a display panel including a display element such as an organic electroluminescence element and a liquid crystal cell.
- This display panel includes a base material such as a glass base material in order to increase the mechanical strength of the display panel.
- the substrate, the broadband wavelength film and the linearly polarizing film were usually provided in this order.
- the polarizer layer of a linearly polarizing film generally tends to shrink in the in-plane direction in a high temperature environment.
- a stress that tends to warp the display panel is generated in the display panel provided with the linearly polarizing film including the polarizer layer. Since warping of the display panel can cause deterioration in image quality, it is desirable to suppress it. As a result of investigation by the present inventor on this warp, it has been found that the warp tends to increase as the distance between the polarizer layer and the substrate of the display panel increases.
- a broadband wavelength film manufactured as a co-stretched film as described above has a ⁇ / 2 layer and a ⁇ / 4 layer in direct contact with each other, or is provided between a ⁇ / 2 layer and a ⁇ / 4 layer.
- the thin film layer can be made thin. Therefore, since the whole broadband wavelength film can be thinned, the distance between the polarizer layer and the substrate of the display panel can be reduced. Therefore, it is possible to suppress warping of the display panel.
- the multidirectional measurement was performed in each azimuth direction of 45 °, 90 °, 135 °, and 180 °, where the azimuth direction with the main surface of the broadband wavelength film was 0 °. Furthermore, the measurement wavelength of the above measurement was 590 nm.
- the in-plane retardation Re the thickness direction retardation Rth, the NZ coefficient and the orientation angle of each layer were determined by fitting calculation from the transmission polarization characteristics measured as described above.
- the fitting calculation was performed by setting the three-dimensional refractive index and the orientation angle of each layer included in the broadband wavelength film as fitting parameters.
- the attached software (“Multi-Layer Analysis” manufactured by Axometrics) of the phase difference meter (AxoScan) was used.
- color difference (DELTA) E * ab when light was irradiated to a circularly-polarizing film from D65 light source was calculated in the (i) front direction and (ii) inclination direction of the said circularly-polarizing film.
- the color difference ⁇ E * ab in the tilt direction was obtained as an average of values calculated for the color difference at the polar angle of 45 ° in the azimuth range of 0 ° to 360 °.
- ⁇ E * ab (i) the polar angle of 0 ° and the azimuth angle of 0 ° of the aluminum mirror not attached with the circularly polarizing film in both the front direction and (ii) the tilt direction Based on the reflected light in the direction.
- the surface reflection component actually generated on the surface of the circularly polarizing film is excluded from the calculation of the color difference ⁇ E * ab.
- the value of the color difference ⁇ E * ab means that the smaller the value, the smaller the color change, which is preferable.
- Example 1 (First step: production of layer (A)) A pellet-shaped norbornene resin (manufactured by Nippon Zeon Co., Ltd .; glass transition temperature 126 ° C.) was dried at 100 ° C. for 5 hours. The dried resin was supplied to an extruder, passed through a polymer pipe and a polymer filter, and extruded from a T-die onto a casting drum. The extruded resin was cooled to obtain a long unstretched film having a thickness of 70 ⁇ m. The obtained film before stretching was wound up on a roll and collected.
- a pellet-shaped norbornene resin manufactured by Nippon Zeon Co., Ltd .; glass transition temperature 126 ° C.
- the film before stretching was pulled out from the roll and continuously supplied to a tenter stretching machine. Then, by this tenter stretching machine, the film before stretching is stretched at a stretching temperature of 135 ° C. and a stretching ratio of 1.5 times in a stretching direction that forms an angle of 45 ° with respect to the width direction of the film before stretching.
- a long oblique stretched film as (A) was obtained.
- the obtained obliquely stretched film had an orientation angle of 45 ° and an in-plane retardation Re of 195 nm.
- the obtained obliquely stretched film was wound up on a roll and collected.
- a liquid composition containing a styrene-maleic anhydride copolymer (“Daylark D332” manufactured by Nova Chemical Co., glass transition temperature 130 ° C., oligomer component content 3% by weight) as a resin having a negative intrinsic birefringence was prepared.
- This liquid composition contained methyl ethyl ketone as a solvent, and the concentration of the styrene-maleic anhydride copolymer in the liquid composition was 10% by weight.
- the obliquely stretched film was pulled out from the roll, and the liquid composition was applied onto the obliquely stretched film. Thereafter, the coated liquid composition was dried to form a styrene-maleic anhydride copolymer layer (thickness 7 ⁇ m) as a layer (B) on the obliquely stretched film.
- a multilayer film comprising an obliquely stretched film as the layer (A) and a styrene-maleic anhydride copolymer layer as the layer (B) was obtained.
- the obtained multilayer film was wound up on a roll and collected.
- the multilayer film was pulled out from the roll and continuously supplied to the longitudinal stretching machine. And by this longitudinal stretching machine, the multilayer film is subjected to free uniaxial stretching at a stretching temperature of 127 ° C. and a stretching ratio of 1.4 times in the longitudinal direction forming an angle of 90 ° with respect to the width direction of the multilayer film. It was.
- a co-stretched film comprising a ⁇ / 2 layer obtained by stretching an obliquely stretched film and a ⁇ / 4 layer obtained by stretching a styrene-maleic anhydride copolymer layer.
- the obtained broadband wavelength film was evaluated by the method described above.
- Example 2 Except having changed the formation method of the layer (B) in a 2nd process into the following extrusion method, manufacture and evaluation of the elongate broadband wavelength film and the circularly-polarizing film were performed by the same operation as Example 1.
- FIG. 1 Example 1
- the obliquely stretched film was pulled out from the roll, and the resin was extruded onto the obliquely stretched film in the form of a film in a molten state at an extrusion temperature of 260 ° C. With the extruded resin attached to the obliquely stretched film, cooling is performed to cure the resin to form a resin layer (thickness 20 ⁇ m) containing a styrene-maleic anhydride copolymer as the layer (B). did.
- Example 3 Except having changed the formation method of the layer (B) in a 2nd process into the following bonding method, manufacture and evaluation of the elongate broadband wavelength film and the circularly-polarizing film were performed by the same operation as Example 1.
- FIG. 3 Except having changed the formation method of the layer (B) in a 2nd process into the following bonding method, manufacture and evaluation of the elongate broadband wavelength film and the circularly-polarizing film were performed by the same operation as Example 1.
- a liquid composition containing a styrene-maleic anhydride copolymer as a resin having the same intrinsic birefringence as that used in Example 1 was prepared.
- the unstretched film produced in the first step of Example 1 was pulled out from the roll, and the liquid composition was applied onto the unstretched film. Thereafter, the coated liquid composition was dried to form a styrene-maleic anhydride copolymer layer (thickness 7 ⁇ m) as a layer (B) on the film before stretching.
- the obliquely stretched film was pulled out from the roll, and an adhesive layer (“CS-9621T” manufactured by Nitto Denko Corporation) was bonded to one side of the obliquely stretched film. Furthermore, the styrene-maleic anhydride copolymer layer formed on the pre-stretched film was bonded to the obliquely stretched film via this adhesive layer, and then the pre-stretched film was peeled off.
- an adhesive layer (“CS-9621T” manufactured by Nitto Denko Corporation) was bonded to one side of the obliquely stretched film. Furthermore, the styrene-maleic anhydride copolymer layer formed on the pre-stretched film was bonded to the obliquely stretched film via this adhesive layer, and then the pre-stretched film was peeled off.
- a layer of the styrene-maleic anhydride copolymer as the layer (B) is formed on the obliquely stretched film via the adhesive layer, and the obliquely stretched film, the adhesive layer, and the styrene-maleic anhydride copolymer are formed.
- a multilayer film with layers in this order was obtained.
- Example 1 The layer (A) used was a film before stretching instead of the obliquely stretched film, the stretching temperature was changed in the third step, and a ⁇ / 4 layer having the same in-plane retardation as in Example 1 was obtained. Therefore, except that the glass transition temperature of the resin having a negative intrinsic birefringence was adjusted, the production and evaluation of a long broadband wavelength film and a circularly polarizing film were performed by the same operation as in Example 1. Specifically, the following operation was performed.
- Example 2 To the same styrene-maleic anhydride copolymer used in Example 1, 5% by weight of triphenyl phosphate as a plasticizer was added to 100% by weight of the styrene-maleic acid copolymer, and the glass transition temperature was adjusted. It was adjusted. A resin containing styrene-maleic anhydride copolymer and phosphoric phenonitrile thus obtained was mixed with methyl ethyl ketone as a solvent to prepare a liquid composition having a solid content concentration of 10% by weight. The unstretched film produced in the first step of Example 1 was pulled out from the roll, and the liquid composition was applied onto the unstretched film.
- triphenyl phosphate as a plasticizer
- the coated liquid composition was dried to form a resin layer (thickness 7 ⁇ m) containing a styrene-maleic anhydride copolymer on the film before stretching.
- a resin layer thickness 7 ⁇ m
- a multilayer film comprising a pre-stretched film and a resin layer containing a styrene-maleic anhydride copolymer was obtained.
- the obtained multilayer film was wound up on a roll and collected.
- This multilayer film was pulled out from the roll and continuously supplied to the longitudinal stretching machine. And with this longitudinal stretching machine, the multilayer film is stretched at a stretching temperature of 128 ° C. in the longitudinal direction forming an angle of 90 ° with respect to the width direction of the multilayer film, and the same stretching ratio as in the third step of Example 1.
- the obtained broadband wavelength film was evaluated by the method described above.
- the broadband wavelength film thus obtained was bonded to a linearly polarizing film in the same manner as in Example 1 to produce a circularly polarizing film.
- the obtained circularly polarizing film was evaluated by the method described above.
- Example 2 A long broadband wavelength was obtained by the same operation as in Example 1, except that the film before stretching was used instead of the obliquely stretched film as the layer (A), and that the stretching direction and stretching ratio in the third step were changed.
- the film was manufactured and evaluated. Specifically, the following operation was performed.
- a liquid composition containing a styrene-maleic anhydride copolymer as a resin having the same intrinsic birefringence as that used in Example 1 was prepared.
- the unstretched film produced in the first step of Example 1 was pulled out from the roll, and the liquid composition was applied onto the unstretched film. Thereafter, the coated liquid composition was dried to form a styrene-maleic anhydride copolymer layer (thickness 7 ⁇ m) on the unstretched film.
- a multilayer film comprising a pre-stretch film and a styrene-maleic anhydride copolymer layer was obtained.
- the obtained multilayer film was wound up on a roll and collected.
- This multilayer film was pulled out from the roll and continuously supplied to a tenter stretching machine. And, by this tenter stretching machine, the multilayer film is stretched in the stretching direction at an angle of 45 ° with respect to the width direction of the multilayer film at a stretch ratio of 1.5 times, and is the same as the third step of Example 1.
- the film was stretched at a stretching temperature to obtain a long broadband wavelength film.
- the obtained broadband wavelength film was evaluated by the method described above.
- the broadband wavelength film thus obtained was bonded to a linearly polarizing film in the same manner as in Example 1 to produce a circularly polarizing film.
- the obtained circularly polarizing film was evaluated by the method described above.
- Example 4 (First step: production of layer (A)) A pellet-shaped norbornene resin (manufactured by Nippon Zeon Co., Ltd .; glass transition temperature 126 ° C.) was dried at 100 ° C. for 5 hours. The dried resin was supplied to an extruder, passed through a polymer pipe and a polymer filter, and extruded from a T-die onto a casting drum. The extruded resin was cooled to obtain a long unstretched film having a thickness of 70 ⁇ m. The obtained film before stretching was wound up on a roll and collected.
- a pellet-shaped norbornene resin manufactured by Nippon Zeon Co., Ltd .; glass transition temperature 126 ° C.
- the film before stretching was pulled out from the roll and continuously supplied to a tenter stretching machine. Then, by this tenter stretching machine, the film before stretching is stretched at a stretching temperature of 135 ° C. and a stretching ratio of 1.5 times in a stretching direction that forms an angle of 45 ° with respect to the width direction of the film before stretching.
- a long oblique stretched film as (A) was obtained.
- the obtained obliquely stretched film had an orientation angle of 45 ° and an in-plane retardation Re of 215 nm.
- the obtained obliquely stretched film was wound up on a roll and collected.
- the obliquely stretched film was pulled out from the roll and subjected to corona treatment on one side.
- the corona treatment was performed under conditions of a line speed of 10 m / min and a nitrogen atmosphere and an output of 1.5 kW.
- a solution for forming a thin film layer was applied to the corona-treated surface using a reverse gravure rotating in the direction opposite to the film transport direction.
- the coated solution was then dried at 100 ° C. During drying, crosslinking of the acrylic polymer in the solution progressed, and a thin film layer containing the crosslinked acrylic polymer was formed.
- a resin having a negative intrinsic birefringence index As a resin having a negative intrinsic birefringence index, a styrene-maleic anhydride copolymer (“Daylark D332” manufactured by Nova Chemical Co.) was prepared. In addition, a mixed solvent containing methyl ethyl ketone and methyl isobutyl ketone at a weight ratio of 8: 2 was prepared. 100 parts of a styrene-maleic anhydride copolymer was dissolved in a mixed solvent, and 5 parts of triphenyl phosphate was further added as a plasticizer to obtain a liquid composition having a solid concentration of 12.5% by weight.
- This liquid composition was applied on the thin film layer by die coating.
- the applied liquid composition was dried at 120 ° C. to form a layer (B) having a thickness of 10 ⁇ m.
- a multilayer film comprising an obliquely stretched film as the layer (A), a thin film layer containing a crosslinked acrylic polymer, and a resin layer containing a styrene-maleic anhydride copolymer as the layer (B). Obtained.
- the obtained multilayer film was wound up on a roll and collected.
- the multilayer film was pulled out from the roll and continuously supplied to the longitudinal stretching machine. And by this longitudinal stretching machine, the multilayer film is subjected to free uniaxial stretching at a stretching temperature of 127 ° C. and a stretching ratio of 1.42 times in the longitudinal direction forming an angle of 90 ° with respect to the width direction of the multilayer film. It was.
- a ⁇ / 2 layer obtained by stretching an obliquely stretched film, a thin film layer (thickness 0.8 ⁇ m), and a ⁇ / layer obtained by stretching a resin layer containing a styrene-maleic anhydride copolymer.
- a broadband wavelength film was obtained as a co-stretched film having four layers in this order. The obtained broadband wavelength film was evaluated by the method described above.
- a linearly polarizing film including a polarizer layer (made of polyvinyl alcohol; thickness: 23 ⁇ m) and a protective film layer (made of triacetyl cellulose; thickness: 40 ⁇ m) provided on one surface of the polarizer layer was prepared.
- the surface of the linear polarizing film on the side of the polarizer layer and the surface of the broadband wavelength film on the side of the ⁇ / 2 layer are bonded together with an adhesive layer (“KRX-7007” manufactured by ADEKA); the thickness is 2 ⁇ m. Obtained.
- a rectangular glass plate (vertical 170 mm, horizontal 100 mm, thickness 0.5 mm) was bonded to the broadband wavelength film side of this sample film with an adhesive layer (“CS-9621T” manufactured by Nitto Denko Corporation; thickness 25 ⁇ m).
- CS-9621T manufactured by Nitto Denko Corporation; thickness 25 ⁇ m.
- the sample plate was placed in an 85 ° C. oven for 24 hours. Thereafter, the sample plate was taken out of the oven and placed on a horizontal plane so that the sample film was on the upper side in the direction of gravity. And the height from a plane to four corners of a glass plate was measured, and the average value was calculated
- Example 3 Manufacture of film corresponding to ⁇ / 2 layer
- the obliquely stretched film produced in the first step of Example 1 was drawn from the roll and continuously supplied to the longitudinal stretching machine. And by this longitudinal stretching machine, the obliquely stretched film is subjected to free uniaxial stretching at a stretching temperature of 127 ° C. and a stretching ratio of 1.42 times in the longitudinal direction forming an angle of 90 ° with respect to the width direction of the obliquely stretched film. It was. Thus, a long biaxially stretched film having an in-plane retardation Re of 270 nm, an orientation angle of 75 °, and a thickness of 40 ⁇ m was obtained.
- a pellet-shaped norbornene resin (manufactured by Nippon Zeon Co., Ltd .; glass transition temperature 126 ° C.) was dried at 100 ° C. for 5 hours. The dried resin was supplied to an extruder, passed through a polymer pipe and a polymer filter, and extruded from a T-die onto a casting drum. The extruded resin was cooled to obtain a long unstretched film having a thickness of 115 ⁇ m. The obtained film before stretching was wound up on a roll and collected.
- the film before stretching was pulled out from the roll and continuously supplied to a tenter stretching machine. Then, by this tenter stretching machine, the film before stretching is stretched at a stretching temperature of 135 ° C. and a stretching ratio of 5.0 times in a stretching direction that forms an angle of 15 ° with respect to the width direction of the film before stretching. An isometrically stretched film was obtained.
- the obtained obliquely stretched film had an orientation angle of 15 °, an in-plane retardation Re of 140 nm, and a thickness of 22 ⁇ m.
- a linearly polarizing film including a polarizer layer (made of polyvinyl alcohol; thickness: 23 ⁇ m) and a protective film layer (made of triacetyl cellulose; thickness: 40 ⁇ m) provided on one surface of the polarizer layer was prepared.
- the surface of the linear polarizing film on the side of the polarizer layer and the biaxially stretched film were bonded together with an adhesive layer (“KRX-7007” manufactured by ADEKA; thickness: 2 ⁇ m).
- the surface of the biaxially stretched film bonded to the linearly polarizing film was subjected to corona treatment. Moreover, the corona treatment was given to the one side of the said diagonally stretched film.
- the corona-treated surface of the biaxially stretched film and the corona-treated surface of the obliquely stretched film were bonded together with an adhesive layer (“CS-9621T” manufactured by Nitto Denko Corporation; thickness 25 ⁇ m).
- CS-9621T manufactured by Nitto Denko Corporation; thickness 25 ⁇ m.
- the angle between the slow axis of the biaxially stretched film and the slow axis of the obliquely stretched film is 60 ° by making the longitudinal direction of the biaxially stretched film and the longitudinal direction of the obliquely stretched film parallel to each other. I went to be.
- a long circular polarizing film comprising a linearly polarizing film, an adhesive layer, a ⁇ / 2 layer as a biaxially stretched film, an adhesive layer, and a ⁇ / 4 layer as an obliquely stretched film in this order.
- This circularly polarizing film was evaluated by the method described above. Further, warpage was evaluated by the same evaluation method as in Example 4 using this circularly polarizing film instead of the sample film.
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Abstract
Description
すなわち、本発明は、下記のものを含む。
前記層(A)上に、固有複屈折が負の樹脂の層(B)を形成して、複層フィルムを得る第二工程と、
前記複層フィルムを延伸して、λ/2層及びλ/4層を備える長尺の広帯域波長フィルムを得る第三工程と、
をこの順に含む、広帯域波長フィルムの製造方法。
〔2〕 前記λ/2層が、前記広帯域波長フィルムの幅方向に対して67.5°±10°の角度をなす遅相軸を有する、〔1〕記載の広帯域波長フィルムの製造方法。
〔3〕 前記λ/4層が、前記広帯域波長フィルムの幅方向に対して0°±20°の角度をなす遅相軸を有する、〔1〕又は〔2〕記載の広帯域波長フィルムの製造方法。
〔4〕 前記層(A)が、当該層(A)の幅方向に対して15°より大きく50°未満の角度をなす遅相軸を有する、〔1〕~〔3〕のいずれか一項に記載の広帯域波長フィルムの製造方法。
〔5〕 前記第二工程が、前記層(A)上に、前記固有複屈折が負の樹脂を含む組成物を塗工することを含む、〔1〕~〔4〕のいずれか一項に記載の広帯域波長フィルムの製造方法。
〔6〕 前記第二工程が、前記層(A)上に、前記固有複屈折が負の樹脂を押し出すことを含む、〔1〕~〔4〕のいずれか一項に記載の広帯域波長フィルムの製造方法。
〔7〕 前記第二工程が、前記層(A)に、前記固有複屈折が負の樹脂のフィルムを貼合することを含む、〔1〕~〔4〕のいずれか一項に記載の広帯域波長フィルムの製造方法。
〔8〕 前記第三工程が、前記複層フィルムを、前記複層フィルムの幅方向に対して90°±20°の角度をなす延伸方向に延伸することを含む、〔1〕~〔7〕のいずれか一項に記載の広帯域波長フィルムの製造方法。
〔9〕 前記λ/2層が、前記層(A)を延伸して得られた層である、〔1〕~〔8〕のいずれか一項に記載の広帯域波長フィルムの製造方法。
〔10〕 前記λ/4層が、前記層(B)を延伸して得られた層である、〔1〕~〔9〕のいずれか一項に記載の広帯域波長フィルムの製造方法。
〔11〕 〔1〕~〔10〕のいずれか一項に記載の製造方法で広帯域波長フィルムを製造する工程と、
前記広帯域波長フィルムと、長尺の直線偏光フィルムとを貼合する工程と、を含む、円偏光フィルムの製造方法。
〔12〕 前記直線偏光フィルムが、当該直線偏光フィルムの長手方向に吸収軸を有する、〔11〕記載の円偏光フィルムの製造方法。
〔13〕 幅方向に対して67.5°±10°の角度をなす遅相軸を有するλ/2層と、
幅方向に対して0°±20°の角度をなす遅相軸を有するλ/4層と、を備えた共延伸フィルムである、長尺の広帯域波長フィルム。
〔14〕 前記λ/2層と前記λ/4層とが、直接に接している、〔13〕記載の長尺の広帯域波長フィルム。
〔15〕 前記λ/2層と前記λ/4層との間に、厚み2μm未満の薄膜層を備える、〔13〕記載の長尺の広帯域波長フィルム。
〔16〕 前記λ/2層のNz係数が、1.0以上である、〔13〕~〔15〕のいずれか一項に記載の長尺の広帯域波長フィルム。
〔17〕 前記λ/2層が、固有複屈折が正の樹脂からなる、〔13〕~〔16〕のいずれか一項に記載の長尺の広帯域波長フィルム。
〔18〕 前記固有複屈折が正の樹脂が、環状オレフィン重合体を含む、〔17〕記載の長尺の広帯域波長フィルム。
〔19〕 前記λ/4層のNz係数が、-0.2±0.2である、〔13〕~〔18〕のいずれか一項に記載の長尺の広帯域波長フィルム。
〔20〕 前記λ/4層が、固有複屈折が負の樹脂からなる、〔13〕~〔19〕のいずれか一項に記載の長尺の広帯域波長フィルム。
〔21〕 前記固有複屈折が負の樹脂が、ポリスチレン系重合体又はセルロース化合物を含む、〔20〕記載の長尺の広帯域波長フィルム。
〔22〕 前記λ/4層の厚みが、15μm以下である、〔13〕~〔21〕のいずれか一項に記載の長尺の広帯域波長フィルム。
〔23〕 前記λ/4層が、可塑剤を含む、〔13〕~〔22〕のいずれか一項に記載の長尺の広帯域波長フィルム。
〔24〕 前記λ/4層における前記可塑剤の量が、0.001重量%以上20重量%以下である、〔23〕に記載の長尺の広帯域波長フィルム。
本発明の広帯域波長フィルムは、従来よりも少ない工程数で効率良く製造できる。
本発明の円偏光フィルムの製造方法によれば、広帯域波長フィルムを少ない工程数で効率良く製造できるので、円偏光フィルムも効率良く製造することが可能である。
図1は、本発明の一実施形態に係る広帯域波長フィルムの製造方法の第一工程で用意される長尺の斜め延伸フィルムとしての層(A)100を模式的に示す斜視図である。また、図2は、本発明の一実施形態に係る広帯域波長フィルムの製造方法の第二工程で得られる複層フィルム200を模式的に示す斜視図である。さらに、図3は、本発明の一実施形態に係る広帯域波長フィルムの製造方法の第三工程で得られる広帯域波長フィルム300を模式的に示す斜視図である。
(1)図1に示すように、長尺の斜め延伸フィルムとしての層(A)100を用意する第一工程と;
(2)層(A)100上に、固有複屈折が負の樹脂の層(B)210を形成して、図2に示す複層フィルム200を得る第二工程と;
(3)複層フィルム200を延伸して、図3に示す長尺の広帯域波長フィルム300を得る第三工程と;
をこの順に含む。
以下、前記の製造方法について、詳細に説明する。
第一工程では、長尺の斜め延伸フィルムとしての層(A)を用意する。この層(A)としては、通常、長尺の樹脂フィルムを当該樹脂フィルムの斜め方向に延伸して得られる斜め延伸フィルムを用いる。また、前記の斜め延伸フィルムとしては、2層以上の層を含む複層構造のフィルムを用いてもよいが、通常は、1層のみを含む単層構造のフィルムを用いる。
広帯域波長フィルムの製造方法は、第一工程において層(A)を用意した後で、必要に応じて、層(A)上に薄膜層を形成する工程を含んでいてもよい。適切な薄膜層を形成することにより、薄膜層は易接着層として機能し、層(A)と層(B)との結着力を高めることができる。また、薄膜層は耐溶媒性があるほうが好ましい。このような薄膜層は、通常、樹脂により形成される。
第一工程において層(A)を用意し、必要に応じて薄膜層を形成した後で、固有複屈折が負の樹脂の層(B)を形成して、複層フィルムを得る第二工程を行う。この第二工程では、層(A)上に、直接、又は、薄膜層等の任意の層を介して間接的に、層(B)を形成する。ここで「直接」とは、層(A)と層(B)との間に任意の層が無いことをいう。
第二工程において層(A)及び層(B)を備える複層フィルムを得た後で、この複層フィルムを延伸して、長尺の広帯域波長フィルムを得る第三工程を行う。第三工程での延伸により、層(A)の遅相軸の方向が調整され、且つ、層(A)の光学特性が調整されて、λ/2層及びλ/4層の一方が得られる。また、第三工程での延伸により、層(B)に遅相軸が現れ、且つ、層(B)に光学特性が発現して、λ/2層及びλ/4層の他方が得られる。
(C1)延伸温度が、好ましくはTgA-20℃以上、より好ましくはTgA-10℃以上、特に好ましくはTgA-5℃以上であり、好ましくはTgA+30℃以下、より好ましくはTgA+25℃以下、特に好ましくはTgA+20℃以下の温度である。
(C2)延伸温度が、好ましくはTgB-20℃以上、より好ましくはTgB-10℃以上、特に好ましくはTgB-5℃以上であり、好ましくはTgB+30℃以下、より好ましくはTgB+25℃以下、特に好ましくはTgB+20℃以下の温度である。
このような延伸温度で延伸を行うことにより、層(A)の光学特性を適切に調整でき、且つ、層(B)に所望の光学特性を発現させることができる。よって、所望の光学特性を有する広帯域波長フィルムを得ることができる。
上述した製造方法により、λ/2層及びλ/4層を備えた共延伸フィルムとして、長尺の広帯域波長フィルムが得られる。上述した製造方法では、層(A)及び層(B)の延伸を、従来のように別々に行うのではなく、第三工程において一緒に行っている。そのため、従来よりも延伸処理の回数を減らすことができるので、広帯域波長フィルムの製造に要する工程数を減らすことができ、したがって、効率の良い製造を実現できる。また、複層フィルムを延伸することで層(A)及び層(B)を共延伸して広帯域波長フィルムを得る前記の製造方法では、λ/2層及びλ/4層それぞれの製造後に両者を貼り合わせる従来の製造方法のように、貼り合わせによる遅相軸方向のズレを生じない。そのため、λ/2層及びλ/4層それぞれの遅相軸の方向を精密に制御することが容易であるので、効果的な色付き抑制が可能な円偏光フィルムを実現できる高品質の広帯域波長フィルムを容易に得ることができる。
例えば、広帯域波長フィルムの製造方法は、広帯域波長フィルムの表面に保護層を設ける工程を含んでいてもよい。
さらに、例えば、広帯域波長フィルムの製造方法は、任意の時点において、層(A)、層(B)、及び薄膜層のうち1又は2以上の表面に、コロナ処理、プラズマ処理等の表面処理を施す工程を含んでいてもよい。よって、例えば、層(A)の表面に表面処理を施した後で、その処理面に層(B)又は薄膜層を形成してもよい。また、例えば、薄膜層の表面に表面処理を施した後で、その処理面に層(B)を形成してもよい。表面処理を行うことにより、当該表面処理を施された面において層同士の結着性を高めることが可能である。
上述した製造方法で製造された広帯域波長フィルムを用いて、長尺の円偏光フィルムを製造することができる。このような円偏光フィルムは、上述した製造方法で広帯域波長フィルムを製造する工程と、この広帯域波長フィルムと長尺の直線偏光フィルムとを貼合する工程と、を含む製造方法により、製造できる。前記の貼合は、直線偏光フィルム、λ/2層及びλ/4層が、厚み方向においてこの順に並ぶように行う。また、貼合には、必要に応じて、接着層又は粘着層を用いてもよい。
偏光子層としては、例えば、適切なビニルアルコール系重合体のフィルムに、適切な処理を適切な順序及び方式で施したものを用いうる。かかるビニルアルコール系重合体の例としては、ポリビニルアルコール及び部分ホルマール化ポリビニルアルコールが挙げられる。フィルムの処理の例としては、ヨウ素及び二色性染料等の二色性物質による染色処理、延伸処理、及び架橋処理が挙げられる。通常、偏光子層を製造するための延伸処理では、延伸前のフィルムを長手方向に延伸するので、得られる偏光子層においては当該偏光子層の長手方向に平行な吸収軸が発現しうる。この偏光子層は、吸収軸と平行な振動方向を有する直線偏光を吸収しうるものであり、特に、偏光度に優れるものが好ましい。偏光子層の厚さは、5μm~80μmが一般的であるが、これに限定されない。
例えば、円偏光フィルムは、傷つき抑制のための保護フィルム層を備えていてもよい。また、例えば、円偏光フィルムは、直線偏光フィルムと広帯域波長フィルムとの接着のために、接着層又は粘着層を備えていてもよい。
有機EL表示装置が円偏光フィルム片を備える場合、通常、有機EL表示装置は表示面に円偏光フィルム片を備える。有機EL表示装置の表示面に、円偏光フィルム片を、直線偏光フィルム側の面が視認側に向くように設けることにより、装置外部から入射した光が装置内で反射して装置外部へ出射することを抑制することができ、その結果、表示装置の表示面のぎらつきを抑制しうる。具体的には、装置外部から入射した光は、その一部の直線偏光のみが直線偏光フィルムを通過し、次にそれが広帯域波長フィルムを通過することにより円偏光となる。円偏光は、表示装置内の光を反射する構成要素(反射電極等)により反射され、再び広帯域波長フィルムを通過することにより、入射した直線偏光の振動方向(偏光軸)と直交する方向に振動方向(偏光軸)を有する直線偏光となり、直線偏光フィルムを通過しなくなる。これにより、反射抑制機能が達成される。また、前記の反射抑制機能が広い波長範囲で得られることにより、表示面の色付きを抑制することができる。
液晶表示装置が円偏光フィルム片を、直線偏光フィルム側の面が視認側に向くように備える場合、装置外部から入射した光が装置内で反射して装置外部へ出射することを抑制することができ、その結果、表示装置の表示面のぎらつき及び色付きを抑制できる。
また、液晶表示装置が円偏光フィルム片を、直線偏光フィルム側の面が光源側に向くように備える場合、この円偏光フィルム片の広帯域波長フィルムが液晶表示装置の液晶セルよりも表示面に近い位置にあると、画像を円偏光で表示することができる。そのため、表示面から出る光を偏光サングラスによって安定して視認することを可能にして、偏光サングラス着用時の画像視認性を高めることができる。
これに対し、上述したように共延伸フィルムとして製造された広帯域波長フィルムは、λ/2層とλ/4層とが直接に接したり、λ/2層とλ/4層との間に設けられる薄膜層を薄くしたりできる。よって、広帯域波長フィルムの全体を薄くできるので、偏光子層と表示パネルの基材との間の距離を小さくできる。したがって、表示パネルの反りを抑制することが可能である。
以下の説明において、量を表す「%」及び「部」は、別に断らない限り、重量基準である。また、以下に説明する操作は、別に断らない限り、常温及び常圧の条件において行った。
〔広帯域波長フィルムの各層の光学特性の測定方法〕
評価対象となる広帯域波長フィルムを、位相差計(Axometrics社製「AxoScan」)のステージに設置した。そして、広帯域波長フィルムを透過する偏光の前記広帯域波長フィルムを透過する前後での偏光状態の変化を、広帯域波長フィルムの透過偏光特性として測定した。この測定は、広帯域波長フィルムの主面に対して極角-55°から55°の範囲で行う多方向測定として行った。また、前記の多方向測定は、広帯域波長フィルムの主面のある方位角方向を0°として、45°、90°、135°及び180°の各方位角方向において行った。さらに、前記の測定の測定波長は、590nmであった。
シミュレーション用のソフトウェアとしてシンテック社製「LCD Master」を用いて、各実施例及び比較例で製造された円偏光フィルムをモデル化し、下記の設定で色差ΔE*abを計算した。
シミュレーション用のモデルでは、平面状の反射面を有するアルミニウムミラーの前記反射面に、広帯域波長フィルムのλ/4層側がミラーに接するように円偏光フィルムを貼り付けた構造を設定した。したがって、このモデルでは、厚み方向において、直線偏光フィルム、λ/2層、λ/4層及びミラーがこの順に設けられた構造が設定された。
そして、前記のモデルにおいて、D65光源から円偏光フィルムに光を照射したときの色差ΔE*abを、前記円偏光フィルムの(i)正面方向及び(ii)傾斜方向において計算した。ここで、傾斜方向の色差ΔE*abは、極角45°の色差を0°~360°の方位角の範囲で計算した値の平均として求めた。また、色差ΔE*abの計算に当たっては、(i)正面方向及び(ii)傾斜方向のいずれにおいても、円偏光フィルムを貼り付けられていないアルミニウムミラーの、極角0°、方位角0°の方向での反射光を基準とした。また、シミュレーションにおいては、実際に円偏光フィルムの表面で発生する表面反射成分については、色差ΔE*abの計算から除いている。色差ΔE*abの値は、値が小さいほど色味変化が少ないことを意味しており、好ましい。
(第一工程:層(A)の製造)
ペレット状のノルボルネン系樹脂(日本ゼオン社製;ガラス転移温度126℃)を100℃で5時間乾燥した。乾燥した樹脂を、押出し機に供給し、ポリマーパイプ及びポリマーフィルターを経て、Tダイからキャスティングドラム上にシート状に押し出した。押し出された樹脂を冷却し、厚み70μmの長尺の延伸前フィルムを得た。得られた延伸前フィルムはロールに巻き取って回収した。
固有複屈折が負の樹脂としてスチレン-無水マレイン酸共重合体(ノヴァ・ケミカル社製「Daylark D332」、ガラス転移温度130℃、オリゴマー成分含有量3重量%)を含む液状組成物を用意した。この液状組成物は溶媒としてメチルエチルケトンを含み、液状組成物におけるスチレン-無水マレイン酸共重合体の濃度は10重量%であった。
複層フィルムをロールから引き出して、縦延伸機に連続的に供給した。そして、この縦延伸機によって、複層フィルムを、当該複層フィルムの幅方向に対して90°の角度をなす長手方向に、延伸温度127℃、延伸倍率1.4倍で自由一軸延伸を行った。これにより、斜め延伸フィルムを延伸して得られたλ/2層と、スチレン-無水マレイン酸共重合体の層を延伸して得られたλ/4層とを備える共延伸フィルムとして、広帯域波長フィルムを得た。得られた広帯域波長フィルムを、上述した方法によって評価した。
長手方向に吸収軸を有する長尺の直線偏光フィルムを用意した。この直線偏光フィルムと、前記の広帯域波長フィルムとを、互いの長手方向を平行にして貼合した。この貼合は、粘着剤(日東電工社製「CS-9621」)を用いて行った。これにより、直線偏光フィルム、λ/2層及びλ/4層をこの順で備える円偏光フィルムを得た。得られた円偏光フィルムについて、上述した方法で評価した。
第二工程における層(B)の形成方法を、下記の押出法に変更したこと以外は、実施例1と同じ操作により、長尺の広帯域波長フィルム及び円偏光フィルムの製造及び評価を行った。
固有複屈折が負の樹脂として、実施例1で用いたのと同じスチレン-無水マレイン酸共重合体を用意した。このスチレン-無水マレイン酸共重合体に可塑剤としてのリン酸トリフェニルを、スチレン-マレイン酸共重合体100重量%に対し10重量%添加し、ガラス転移温度を調整した。このようにガラス転移温度を調整したことで、層(B)の厚みが実施例1よりも厚くても、実施例1と同じ条件の第三工程によって、実施例1と同じ光学特性を有するλ/4層を得ることができる。こうして得られたスチレン-無水マレイン酸共重合体及びリン酸フェニトリルを含む樹脂を樹脂押出型としてのダイを備えた押出機に充填した。
第二工程における層(B)の形成方法を、下記の貼合法に変更したこと以外は、実施例1と同じ操作により、長尺の広帯域波長フィルム及び円偏光フィルムの製造及び評価を行った。
実施例1において用いたのと同じ固有複屈折が負の樹脂としてスチレン-無水マレイン酸共重合体を含む液状組成物を用意した。実施例1の第一工程で製造した延伸前フィルムをロールから引き出し、この延伸前フィルム上に前記の液状組成物を塗工した。その後、塗工された液状組成物を乾燥させて、延伸前フィルム上に層(B)としてのスチレン-無水マレイン酸共重合体の層(厚み7μm)を形成した。
層(A)として斜め延伸フィルムの代わりに延伸前フィルムを用いたこと、第三工程での延伸温度を変更したこと、及び、実施例1と同じ面内レターデーションを有するλ/4層を得るために固有複屈折が負の樹脂のガラス転移温度を調整したこと以外は、実施例1と同じ操作によって、長尺の広帯域波長フィルム及び円偏光フィルムの製造及び評価を行った。具体的には、下記のような操作を行った。
こうして得られた広帯域波長フィルムを、実施例1と同じく直線偏光フィルムと貼合して、円偏光フィルムを製造した。得られた円偏光フィルムについて、上述した方法で評価した。しかし、この円偏光フィルムは、吸収軸及び遅相軸の関係が円偏光フィルムとして機能するための範囲から外れ、十分な反射抑制効果が得られなかった。そのため、色付き抑制機能を評価できる程度に意味のある色差ΔE*abは得られなかった。
層(A)として斜め延伸フィルムの代わりに延伸前フィルムを用いたこと、並びに、第三工程における延伸方向及び延伸倍率を変更したこと以外は、実施例1と同じ操作によって、長尺の広帯域波長フィルムの製造及び評価を行った。具体的には、下記のような操作を行った。
こうして得られた広帯域波長フィルムを、実施例1と同じく直線偏光フィルムと貼合して、円偏光フィルムを製造した。得られた円偏光フィルムについて、上述した方法で評価した。
前記の実施例1~3及び比較例1~2の結果を、下記の表1に示す。表1において、略称の意味は、下記のとおりである。
COP:ノルボルネン重合体。
ST:スチレン-無水マレイン酸重合体。
Re:面内レターデーション。
Rth:厚み方向のレターデーション。
配向角:幅方向に対して遅相軸がなす角度。
総厚:λ/2層とλ/4層との合計厚み。実施例3では、粘着層の厚みは総厚に含まない。
斜め:斜め方向。
縦:長手方向。
(第一工程:層(A)の製造)
ペレット状のノルボルネン系樹脂(日本ゼオン社製;ガラス転移温度126℃)を100℃で5時間乾燥した。乾燥した樹脂を、押出し機に供給し、ポリマーパイプ及びポリマーフィルターを経て、Tダイからキャスティングドラム上にシート状に押し出した。押し出された樹脂を冷却し、厚み70μmの長尺の延伸前フィルムを得た。得られた延伸前フィルムはロールに巻き取って回収した。
アクリルポリマー(荒川化学製「DA105」)と、これを架橋させるためのイソシアネート系架橋剤(荒川化学製「CLシリーズ」)とを、重量比10:3で混合し、メチルイソブチルケトンで固形分濃度20%に希釈して、薄膜層形成用の溶液を得た。
固有複屈折率が負の樹脂として、スチレン-無水マレイン酸共重合体(ノヴァ・ケミカル社製「Daylark D332」)を用意した。また、メチルエチルケトンとメチルイソブチルケトンとを重量比8:2で含む混合溶媒を用意した。スチレン-無水マレイン酸共重合体100部を混合溶媒に溶かし、更に可塑剤としてリン酸トリフェニルを5部添加して、固形分濃度12.5重量%の液状組成物を得た。
複層フィルムをロールから引き出して、縦延伸機に連続的に供給した。そして、この縦延伸機によって、複層フィルムを、当該複層フィルムの幅方向に対して90°の角度をなす長手方向に、延伸温度127℃、延伸倍率1.42倍で自由一軸延伸を行った。これにより、斜め延伸フィルムを延伸して得られたλ/2層と、薄膜層(厚み0.8μm)と、スチレン-無水マレイン酸共重合体を含む樹脂層を延伸して得られたλ/4層とを、この順で備える共延伸フィルムとして、広帯域波長フィルムを得た。得られた広帯域波長フィルムを、上述した方法によって評価した。
偏光子層(ポリビニルアルコール製;厚み23μm)と、この偏光子層の片面に設けられた保護フィルム層(トリアセチルセルロース製;厚み40μm)とを備える直線偏光フィルムを用意した。この直線偏光フィルムの偏光子層側の面と、広帯域波長フィルムのλ/2層側の面とを、接着層(ADEKA社製「KRX-7007」;厚み2μm)によって貼り合わせて、サンプルフィルムを得た。このサンプルフィルムの広帯域波長フィルム側に、矩形のガラス板(縦170mm、横100mm、厚み0.5mm)を、粘着層(日東電工社製「CS-9621T」;厚み25μm)によって貼り合せた。ガラス板からはみ出したサンプルフィルムの部分を取り除いて、反り評価用のサンプル板を得た。
このサンプル板を、85℃のオーブンに24時間入れた。
その後、サンプル板をオーブンから取り出し、サンプルフィルムが重力方向上側になるように、水平な平面上に置いた。そして、平面からガラス板の4角までの高さを測定し、その平均値を反り量として求めた。
得られた広帯域波長フィルムを用いて、実施例1と同じ方法により、円偏光フィルムの製造及び評価を行った。
(λ/2層に相当するフィルムの製造)
実施例1の第一工程で製造した斜め延伸フィルムをロールから引き出し、縦延伸機に連続的に供給した。そして、この縦延伸機によって、斜め延伸フィルムを、当該斜め延伸フィルムの幅方向に対して90°の角度をなす長手方向に、延伸温度127℃、延伸倍率1.42倍で自由一軸延伸を行った。これにより、面内レターデーションReが270nm、配向角が75°、厚み40μmの長尺の二軸延伸フィルムを得た。
ペレット状のノルボルネン系樹脂(日本ゼオン社製;ガラス転移温度126℃)を100℃で5時間乾燥した。乾燥した樹脂を、押出し機に供給し、ポリマーパイプ及びポリマーフィルターを経て、Tダイからキャスティングドラム上にシート状に押し出した。押し出された樹脂を冷却し、厚み115μmの長尺の延伸前フィルムを得た。得られた延伸前フィルムはロールに巻き取って回収した。
偏光子層(ポリビニルアルコール製;厚み23μm)と、この偏光子層の片面に設けられた保護フィルム層(トリアセチルセルロース製;厚み40μm)とを備える直線偏光フィルムを用意した。この直線偏光フィルムの偏光子層側の面と、前記の二軸延伸フィルムとを、接着層(ADEKA社製「KRX-7007」;厚み2μm)によって貼り合わせた。
前記の実施例4及び比較例3の結果を、下記の表2に示す。表2において、略称の意味は、表1と同じである。
200 複層フィルム
210 層(B)
300 広帯域波長フィルム
Claims (24)
- 長尺の斜め延伸フィルムとしての層(A)を用意する第一工程と、
前記層(A)上に、固有複屈折が負の樹脂の層(B)を形成して、複層フィルムを得る第二工程と、
前記複層フィルムを延伸して、λ/2層及びλ/4層を備える長尺の広帯域波長フィルムを得る第三工程と、
をこの順に含む、広帯域波長フィルムの製造方法。 - 前記λ/2層が、前記広帯域波長フィルムの幅方向に対して67.5°±10°の角度をなす遅相軸を有する、請求項1記載の広帯域波長フィルムの製造方法。
- 前記λ/4層が、前記広帯域波長フィルムの幅方向に対して0°±20°の角度をなす遅相軸を有する、請求項1又は2記載の広帯域波長フィルムの製造方法。
- 前記層(A)が、当該層(A)の幅方向に対して15°より大きく50°未満の角度をなす遅相軸を有する、請求項1~3のいずれか一項に記載の広帯域波長フィルムの製造方法。
- 前記第二工程が、前記層(A)上に、前記固有複屈折が負の樹脂を含む組成物を塗工することを含む、請求項1~4のいずれか一項に記載の広帯域波長フィルムの製造方法。
- 前記第二工程が、前記層(A)上に、前記固有複屈折が負の樹脂を押し出すことを含む、請求項1~4のいずれか一項に記載の広帯域波長フィルムの製造方法。
- 前記第二工程が、前記層(A)に、前記固有複屈折が負の樹脂のフィルムを貼合することを含む、請求項1~4のいずれか一項に記載の広帯域波長フィルムの製造方法。
- 前記第三工程が、前記複層フィルムを、前記複層フィルムの幅方向に対して90°±20°の角度をなす延伸方向に延伸することを含む、請求項1~7のいずれか一項に記載の広帯域波長フィルムの製造方法。
- 前記λ/2層が、前記層(A)を延伸して得られた層である、請求項1~8のいずれか一項に記載の広帯域波長フィルムの製造方法。
- 前記λ/4層が、前記層(B)を延伸して得られた層である、請求項1~9のいずれか一項に記載の広帯域波長フィルムの製造方法。
- 請求項1~10のいずれか一項に記載の製造方法で広帯域波長フィルムを製造する工程と、
前記広帯域波長フィルムと、長尺の直線偏光フィルムとを貼合する工程と、を含む、円偏光フィルムの製造方法。 - 前記直線偏光フィルムが、当該直線偏光フィルムの長手方向に吸収軸を有する、請求項11記載の円偏光フィルムの製造方法。
- 幅方向に対して67.5°±10°の角度をなす遅相軸を有するλ/2層と、
幅方向に対して0°±20°の角度をなす遅相軸を有するλ/4層と、を備えた共延伸フィルムである、長尺の広帯域波長フィルム。 - 前記λ/2層と前記λ/4層とが、直接に接している、請求項13記載の長尺の広帯域波長フィルム。
- 前記λ/2層と前記λ/4層との間に、厚み2μm未満の薄膜層を備える、請求項13記載の長尺の広帯域波長フィルム。
- 前記λ/2層のNz係数が、1.0以上である、請求項13~15のいずれか一項に記載の長尺の広帯域波長フィルム。
- 前記λ/2層が、固有複屈折が正の樹脂からなる、請求項13~16のいずれか一項に記載の長尺の広帯域波長フィルム。
- 前記固有複屈折が正の樹脂が、環状オレフィン重合体を含む、請求項17記載の長尺の広帯域波長フィルム。
- 前記λ/4層のNz係数が、-0.2±0.2である、請求項13~18のいずれか一項に記載の長尺の広帯域波長フィルム。
- 前記λ/4層が、固有複屈折が負の樹脂からなる、請求項13~19のいずれか一項に記載の長尺の広帯域波長フィルム。
- 前記固有複屈折が負の樹脂が、ポリスチレン系重合体又はセルロース化合物を含む、請求項20記載の長尺の広帯域波長フィルム。
- 前記λ/4層の厚みが、15μm以下である、請求項13~21のいずれか一項に記載の長尺の広帯域波長フィルム。
- 前記λ/4層が、可塑剤を含む、請求項13~22のいずれか一項に記載の長尺の広帯域波長フィルム。
- 前記λ/4層における前記可塑剤の量が、0.001重量%以上20重量%以下である、請求項23に記載の長尺の広帯域波長フィルム。
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