KR101796893B1 - Method for manufacturing a laminated film - Google Patents

Abstract

The present invention provides a method for producing a laminated film excellent in the degree of polarization.
One aspect of the method for producing a laminated film of the present invention includes a first measuring step of measuring an angle of an absorption axis of a polarizer, a second measuring step of measuring an angle of a fast axis of the retardation film with respect to a predetermined direction, And a phase difference film bonding step of bonding a bonding surface of the retardation film to a bonding surface of the polarizing film, And the phase difference film is joined to the polarizing film by aligning the longitudinal direction of the polarizing film and the longitudinal direction of the retardation film in the phase difference film bonding step.

Description

METHOD FOR MANUFACTURING A LAMINATED FILM [0002]

The present invention relates to a method for producing a laminated film.

A configuration in which a retarder is bonded to a polarizer formed of polyvinyl alcohol (PVA) resin is known (for example, Patent Document 1). Such a laminated film is used in liquid crystal display devices such as a personal computer, a TV, a monitor, a cellular phone, and a PDA (Personal Digital Assistant).

Patent Document 1: Japanese Patent Laid-Open Publication No. 2011-186481

In such a laminated film, there is a problem that the absorption axis of the polarizer and the fast axis of the retardation film (retardation film) are distorted to lower the degree of polarization. As a result, when the laminated film is used in a liquid crystal display device or the like, the contrast of the liquid crystal display device is lowered.

In view of the above problems, one aspect of the present invention is to provide a method for producing a laminated film excellent in the degree of polarization.

One aspect of the method for producing a laminated film of the present invention is a method for producing a laminated film comprising a polarizing film including a polarizer in which a dichroic dye is oriented in a polyvinyl alcohol based resin and a retardation film bonded to the polarizing film A polarizing film preparation step of preparing the polarizing film; a retardation film preparing step of preparing the retardation film; and a step of preparing a polarizing film and a retardation film, wherein the polarizing film and the retardation film are laminated, A second measurement step of measuring an angle of a fast axis of the retardation film with respect to the predetermined direction, and a second measurement step of measuring the angle of the fast axis of the polarizing film with respect to the retardation film Wherein the polarizing film and the polarizing film are bonded such that a relative angle between the absorption axis and the fast axis is less than a predetermined angle, And a phase difference film joining step of joining the joining face of the retardation film to the joining face of the polarizing film, wherein in the phase difference film joining step, The polarizing film is unwound from the roll of the polarizing film on which the polarizing film is wound and the longitudinal direction of the polarizing film and the longitudinal direction of the retardation film are aligned with each other while the polarizing film is unwound from the disk roll on which the strip- And the retardation film is bonded to the polarizing film.

One aspect of the method for producing a laminated film of the present invention is a method for producing a laminated film comprising a polarizing film including a polarizer in which a dichroic dye is oriented in a polyvinyl alcohol based resin and a retardation film bonded to the polarizing film A polarizing film preparation step of preparing the polarizing film; a retardation film preparing step of preparing the retardation film; and a step of preparing a polarizing film and a retardation film, wherein the polarizing film and the retardation film are laminated, A second measurement step of measuring an angle of a phase axis of the retardation film with respect to the predetermined direction, and a second measurement step of measuring the angle of the retardation film with respect to the polarizing film and the retardation film Wherein the polarizing film and the polarizing film are bonded such that a relative angle between the absorption axis and the slow axis is less than a predetermined angle, And a phase difference film joining step of joining the joining face of the retardation film to the joining face of the polarizing film, wherein in the phase difference film joining step, The polarizing film is unwound from the roll of the polarizing film on which the polarizing film is wound and the longitudinal direction of the polarizing film and the longitudinal direction of the retardation film are aligned with each other while the polarizing film is unwound from the disk roll on which the strip- And the retardation film is bonded to the polarizing film.

The predetermined angle may be 0.24 DEG.

Wherein the direction of joining the joining faces is selected so that the relative angle is less than the predetermined angle in the selecting step, and in the joining step of the phase difference films, based on the joining direction selected, And the bonding surface of the retardation film is bonded to the surface of the substrate.

Wherein the polarizing film preparation step includes a polarizing film forming step of forming the polarizing film and the polarizing film forming step includes a polarizing step of forming the polarizing element and a protective film bonding step of bonding a protective film to the polarizing element And the first measuring step may be performed after the polarizer forming step and before the protective film bonding step.

The first measuring step may be performed after the polarizing film preparing step and before the selecting step.

A plurality of the retardation films may be prepared in the retardation film preparing step and the bonding surfaces of the retardation films may be selected from both surfaces of the plurality of retardation films in the selecting step.

A plurality of the polarizing films may be prepared in the polarizing film preparing step and the joining surface of the polarizing film may be selected from both surfaces of the plurality of polarizing films in the selecting step.

Wherein in the first measurement step, the measurement is performed at a plurality of points along the width direction of the polarizing film, and in the second measurement step, the measurement is performed at a plurality of points along the width direction of the retardation film, The bonding surface may be selected such that the relative angle is less than the predetermined angle in a plurality of portions of the polarizing film and the retardation film which are mutually opposed to each other.

According to one aspect of the present invention, there is provided a method for producing a laminated film excellent in the degree of polarization.

1 is a cross-sectional view showing a laminated film of this embodiment.
Fig. 2 is a flowchart showing a procedure of the method for producing a laminated film of the first embodiment.
3 is a schematic diagram showing the procedure of the polarizing film preparing step in the first embodiment.
4 is a perspective view showing the procedure of the phase difference film bonding step in the first embodiment.
Fig. 5 is a plan view showing the laminated film in Fig. 4; Fig.
Fig. 6 is a perspective view showing another procedure of the phase difference film bonding step in the first embodiment. Fig.
7 is a plan view showing the laminated film in Fig.
8A is an explanatory diagram for explaining rewinding of a disk roll.
8B is an explanatory view for explaining rewinding of the disk roll.
8C is an explanatory view for explaining the rewinding of the disk roll.
Fig. 9 is a flow chart showing a procedure of the method for producing a laminated film of the second embodiment.

Hereinafter, a method for manufacturing a laminated film according to an embodiment of the present invention will be described with reference to the drawings. On the other hand, the scope of the present invention is not limited to the following embodiments, but can be arbitrarily changed within the technical scope of the present invention. In the following drawings, the scale and number in each structure may be different from the scale and the number in the actual structure in order to make each structure easy to understand.

First, the laminated film 100 produced in this embodiment will be described. 1 is a cross-sectional view showing a laminated film 100 of the present embodiment. 1, the laminated film 100 includes a polarizing film 1, a retardation film 13, and an adhesive layer 14. The polarizing film 1, the adhesive layer 14 and the retardation film 13 are laminated in this order. Although not shown, the laminated film 100 of the present embodiment is in the shape of a long belt. The laminated film 100 may be wound, for example, on a core material and stored as a disk roll.

In the following description, the direction in which the respective layers are laminated in the laminated film 100 is simply referred to as " lamination direction ", and the longitudinal direction orthogonal to the lamination direction in the laminated film 100 is (The first direction) ", and the width direction orthogonal to both the lamination direction and the longitudinal direction of the laminated film 100 is simply referred to as " width direction (second direction) " Sometimes called.

In the drawings, the three-dimensional orthogonal coordinate system (XYZ coordinate system) is appropriately shown. In the three-dimensional rectangular coordinate system, the Z-axis direction is parallel to the lamination direction, the Y-axis direction is parallel to the width direction, and the X-axis direction is parallel to the longitudinal direction. In the following description, in the lamination direction, the positive side in the Z axis direction may be referred to as " upper side ", and the negative side in the Z axis direction may be referred to as " lower side ". In the width direction, the positive side in the Y-axis direction may be referred to as " right side ", and the negative side in the Y-axis direction may be referred to as " left side ". The upper, lower, right, and left sides are names used for simply describing the relative positional relationship of each part. The posture of each part, the actual posture of the laminated film, and the manner of use of the laminated film are not limited.

The polarizing film 1 includes a polarizer 10, a protective film 11, and an adhesive layer 12. The polarizer 10, the adhesive layer 12 and the protective film 11 are laminated in this order.

The polarizer 10 is a layer in which a dichroic dye is oriented in a polyvinyl alcohol-based resin. In this embodiment, the absorption axis of the polarizer 10 is arranged along the longitudinal direction, for example, and the transmission axis of the polarizer 10 is arranged along the width direction, for example.

Here, in the present specification, any of the axes are disposed along any direction includes not only parallel axes of certain axes and certain directions, but also parallel axes of certain axes and certain directions . That is, for example, the absorption axis of the polarizer 10 is arranged along the longitudinal direction, which means that the axial direction of the absorption axis of the polarizer 10 is substantially parallel to the longitudinal direction. The direction in which the axis of the shaft is substantially parallel with the direction in which the axis is formed includes an angle formed by an axial direction of a certain axis with a direction within a range of, for example, within ± 15 degrees.

Examples of the polyvinyl alcohol-based resin as the material for forming the polarizer 10 include polyvinyl alcohol resin, polyvinyl alcohol resin derivatives, and modified bodies of polyvinyl alcohol resin derivatives. Examples of the polyvinyl alcohol resin derivative include polyvinylformal, polyvinyl acetal, and polyvinyl butyral. As the modified body of the polyvinyl alcohol resin derivative, for example, the above-mentioned polyvinyl alcohol resin derivative is mixed with an olefin such as ethylene or propylene; Unsaturated carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid; Alkyl esters of unsaturated carboxylic acids; Or acrylamide or the like.

The average degree of polymerization of the polyvinyl alcohol-based resin is preferably 100 or more and 10000 or less, more preferably 1000 or more and 10000 or less, still more preferably 1,500 or more and 8,000 or less, still more preferably 2,000 or more and 5,000 or less. When the average degree of polymerization of the polyvinyl alcohol-based resin is less than 100, it is difficult to obtain suitable optical characteristics. When the average degree of polymerization is more than 10000, the solubility in water is lowered and it becomes difficult to prepare a coating solution 33 for a resin layer Because. In the present specification, the average degree of polymerization of the polyvinyl alcohol-based resin is determined, for example, by a method determined by JIS K 6727 (1994).

The polyvinyl alcohol-based resin as a material for forming the polarizer 10 is preferably saponified. The degree of saponification of the polyvinyl alcohol-based resin is preferably from 80.0 mol% to 100.0 mol%, more preferably from 90.0 mol% to 99.5 mol%, still more preferably from 93.0 mol% to 99.5 mol%. If the saponification degree of the polyvinyl alcohol-based resin is less than 80 mol%, it is difficult to obtain suitable optical characteristics.

The saponification degree of the polyvinyl alcohol-based resin is represented by the mol% in which the acetic acid group contained in the polyvinyl alcohol-based resin as the raw material of the polyvinyl alcohol-based resin is changed to the hydroxyl group by the saponification process. .

(Formula 1) saponification degree (mol%) = (number of hydroxyl groups) / (number of hydroxyl groups + number of acetic acid groups) x 100

In the present specification, the degree of saponification of the polyvinyl alcohol-based resin is determined, for example, by a method determined by JIS K 6727 (1994).

The polarizer 10 may contain an additive such as a plasticizer or a surfactant. Examples of plasticizers include condensates of polyols and polyols. Examples of the condensate of the polyol and the polyol include glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol, and polyethylene glycol. The content of the plasticizer in the polarizer 10 is not particularly limited, but is preferably 20 mass% or less, for example.

The thickness of the polarizer 10 is not particularly limited, and is, for example, 3 mu m or more and 50 mu m or less, preferably 5 mu m or more and 15 mu m or less. In the present specification, the thickness of a certain film (layer) is a dimension in a lamination direction of a certain film (layer), and also includes an average thickness of a certain film (layer). That is, the thickness of the polarizer also includes the average thickness of the polarizer.

Examples of the dichroic dye which is oriented in the polyvinyl alcohol-based resin include iodine and organic dyes.

The protective film 11 is bonded to the lower surface 10a of the polarizer 10 through the adhesive layer 12.

The protective film 11 may be a simple protective film having no optical function or a protective film having an optical function such as a brightness enhancement film.

The material for forming the protective film 11 is not particularly limited, and examples thereof include a cyclic polyolefin-based resin film; Acetic acid cellulose-based resin film made of a resin such as triacetylcellulose, diacetylcellulose and the like; A polyester resin film made of a resin such as polyethylene terephthalate, polyethylene naphthalate, or polybutylene terephthalate; A polycarbonate-based resin film; Acrylic resin film; And a polypropylene resin film.

The cyclic polyolefin-based resin film may be uniaxially stretched or biaxially stretched. By stretching, any phase difference can be imparted to the cyclic polyolefin-based resin film.

The cyclic polyolefin-based resin film generally has poor surface activity. Therefore, in the case where the protective film 11 is a cyclic polyolefin based resin film, the lower surface of the protective film 11 to be bonded to the polarizer 10 is subjected to plasma treatment, corona treatment, ultraviolet ray irradiation treatment, flame (flame) treatment , Saponification treatment, and the like. Particularly, plasma treatment and corona treatment that can be performed relatively easily are suitable.

When the protective film 11 is a cellulose acetate based resin film, a liquid crystal layer or the like may be formed on the surface of the protective film 11 in order to improve the viewing angle characteristics. Further, the protective film 11 may be a film obtained by stretching a cellulose acetate resin film to give a retardation. When the protective film 11 is a cellulose acetate-based resin film, the saponification treatment is generally applied to the lower surface of the protective film 11 in order to improve the adhesion with the polarizing film 1. As the saponification treatment, a method of immersing in an aqueous solution of an alkali such as sodium hydroxide and potassium hydroxide can be adopted.

On the surface of the protective film 11, an optical layer such as a hard coat layer, an antiglare layer, and an antireflection layer may be formed. The method of forming these optical layers on the surface of the protective film 11 is not particularly limited and a known method can be used.

The thickness of the protective film 11 is preferably as small as possible, preferably 90 占 퐉 or less, and more preferably 50 占 퐉 or less because of the requirement for thinning. If the thickness of the protective film 11 is too thin, the strength of the protective film 11 is lowered and the workability is lowered. Therefore, the thickness of the protective film 11 is preferably 5 m or more.

The adhesive layer 12 is laminated on the lower surface 10a of the polarizer 10. The adhesive layer 12 is a layer which adheres the polarizer 10 and the protective film 11 to each other. As the material for forming the adhesive layer 12, for example, an aqueous adhesive, an ultraviolet curable adhesive, an electron beam curable adhesive and the like are preferable, and an aqueous adhesive is more preferable. As the water-based adhesive, for example, an aqueous solution of a polyvinyl alcohol-based resin, an aqueous solution containing a common crosslinking agent in an aqueous solution of a polyvinyl alcohol-based resin, and a urethane emulsion adhesive. Further, a metal compound filler may be contained in the adhesive layer 12.

Although not shown, a primer layer may be provided on the upper surface 10b of the polarizer 10. The primer layer is provided to improve adhesion between the base film 20 and the resin layer 34 in the polarizing film preparation step (S11) described later. The primer layer is formed of a resin containing a component capable of improving the above-mentioned adhesion. The resin forming the primer layer is preferably a thermoplastic resin excellent in transparency, thermal stability, stretchability and the like. Examples of the resin forming the primer layer include (meth) acrylic resins, polyvinyl alcohol resins, and the like. Particularly, as the resin forming the primer layer, a polyvinyl alcohol-based resin is preferable. This is because adhesion between the base film 20 and the resin layer 34 described below can be satisfactorily obtained.

The polyvinyl alcohol-based resin used as the resin for forming the primer layer can be selected in the same manner as the polyvinyl alcohol-based resin of the polarizer 10 described above. The resin forming the primer layer may be the same as or different from the polyvinyl alcohol-based resin of the polarizer 10.

The thickness of the primer layer is preferably 0.05 탆 or more and 1 탆 or less, for example, and more preferably 0.1 탆 or more and 0.4 탆 or less. When the thickness of the primer layer is smaller than 0.05 占 퐉, the adhesiveness between the base film 20 and the resin layer 34 described later becomes smaller, and when the thickness is larger than 1 占 퐉, the thickness of the laminated film 100 to be produced tends to increase to be.

The retardation film 13 is bonded to the polarizing film 1 via an adhesive layer 14. [ More specifically, the retardation film 13 is bonded to the upper surface 10b of the polarizer 10 through the adhesive layer 14. [ The retardation film 13 has a function of imparting a phase difference to light passing therethrough. The fast axis of the phase difference film 13 is arranged along the longitudinal direction, for example, and the slow axis of the phase difference film 13 is arranged along the width direction, for example. That is, in this embodiment, the fast axis of the retardation film 13 and the absorption axis of the polarizer 10 are arranged along the same direction (longitudinal direction). In this embodiment, the relative angle between the absorption axis of the polarizer 10 and the fast axis of the retardation film 13 is, for example, less than 0.24 degrees.

In this specification, the relative angle between the absorption axis of the polarizer and the fast axis of the retardation film includes the absolute value of the difference between the angle of the absorption axis of the polarizer with respect to the predetermined direction and the angle of the fast axis of the retardation film with respect to the predetermined direction.

It is preferable that the retardation film 13 is formed of a resin which is excellent in transparency and can exhibit an appropriate retardation value by stretching. As the resin for forming the retardation film 13, for example, triacetyl cellulose (TAC) based resin; Polycarbonate resin; Polyvinyl alcohol-based resin; Polystyrene type resin; (Meth) acrylate-based resin; Polyolefin resins such as cyclic polyolefin resins and polypropylene resins; Polyarylate resins; Polyimide resin; And polyamide-based resins.

The film made of the above-mentioned resin is stretched by a suitable method such as uniaxial or biaxial to obtain a retardation film 13 to which an appropriate retardation is given.

The retardation film 13 may be a wave plate such as a quarter wave plate and a half wave plate, or may be a viewing angle compensation film. The thickness of the retardation film 13 is about 20 to 200 mu m and preferably 20 to 120 mu m.

The adhesive layer 14 may be laminated on the upper surface 10b of the polarizer 10 through a primer layer (not shown). The adhesive layer 14 is a layer that adheres the polarizer 10 and the retardation film 13 to each other. As a material for forming the adhesive layer 14, for example, a forming material such as the adhesive layer 12 can be used. The material for forming the adhesive layer 12 and the material for forming the adhesive layer 14 may be the same or different.

As a material for forming the adhesive layer 14, for example, it is preferable to cure by irradiation with activation energy, and ultraviolet ray curable resin which is cured by irradiating ultraviolet light as activation energy is more preferable. As the ultraviolet ray-curable resin, it is preferable to use a resin which contains a cationic polymerization initiator together with an epoxy compound and is cured by cationic polymerization when the activation energy (ultraviolet ray) is irradiated.

Next, a method for manufacturing the laminated film 100 of the present embodiment will be described.

≪ First Embodiment >

2 is a flow chart showing a procedure of a manufacturing method of the laminated film 100 of the present embodiment. 2, the polarizing film preparing step S11, the retardation film preparing step S12, the fast axis measuring step (second measuring step) (S13), a selection step (S14), and a phase difference film splicing step (S15).

The polarizing film preparation step (S11) is a step of preparing the polarizing film (1). In the present embodiment, the polarizing film preparation step (S11) is a polarizing film forming step for forming the polarizing film (1). The polarizing film preparation step S11 includes a resin layer forming step S11a, a stretching step S11b, a dyeing step S11c, an absorption axis measuring step S11d, (S11e). The resin layer forming step (S11a), the stretching step (S11b) and the dyeing step (S11c) constitute a polarizer forming step (S11f) for forming the polarizer (10).

3 is a schematic diagram showing the procedure of the polarizing film preparation step (S11). As shown in Fig. 3, in the present embodiment, the polarizing film 1 is produced while conveying the base film 20 in the form of a disk roll in the longitudinal direction by the nip roll and the conveying roll. On the other hand, in Fig. 3, the respective steps are performed continuously, but the film may be rolled up in the form of a roll each time the respective steps are completed, and may be returned to the next step.

The material of the base film 20 is not particularly limited as long as it can be stretched together with the resin layer 34 described later in the stretching step S11b. The material of the base film 20 is, for example, a thermoplastic resin. The thermoplastic resin used as the material of the base film 20 is preferably excellent in transparency, mechanical strength, thermal stability and stretchability.

Specifically, examples of the thermoplastic resin used as the material of the base film 20 include polyolefin resins such as a chain polyolefin resin and a cyclic polyolefin resin (norbornene resin and the like); Polyester-based resin; (Meth) acrylic resins; Cellulose ester-based resins such as cellulose triacetate and cellulose diacetate; Polycarbonate resin; Polyvinyl alcohol-based resin; Polyvinyl acetate resin; Polyarylate resins; Polystyrene type resin; Polyether sulfone type resin; Polysulfone resins; Polyamide based resin; Polyimide resin; And mixtures and copolymers of these resins.

The base film 20 is composed of one or more thermoplastic resins among the above-mentioned thermoplastic resins. The base film 20 may have a single-layer structure or a multi-layer structure.

The thickness of the base film 20 is not particularly limited, but is preferably 1 占 퐉 or more and 500 占 퐉 or less, more preferably 1 占 퐉 or more and 300 占 퐉 or less, and more preferably 5 占 퐉 or more and 200 占 퐉 or less And still more preferably 5 mu m or more and 150 mu m or less. The dimension of the base film 20 in the width direction is, for example, 500 mm or more.

The tensile modulus of elasticity in the longitudinal direction of the base film 20 is preferably 140 MPa or more at 80 캜. The tensile elastic modulus in the longitudinal direction of the base film 20 is more preferably 150 MPa or more at 80 캜, and more preferably 155 MPa or more. This is for suppressing heat shrinkage of the base film 20 in a drying step to be described later. In the present specification, the tensile modulus of elasticity in the longitudinal direction of the base film 20 is measured by, for example, Autograph (registered trademark) (manufactured by Shimadzu Seisakusho Co., Ltd., model: AG-IS). Specifically, it is measured in accordance with JIS K 7163.

The resin layer forming step (S11a) is a step of forming a resin layer (34) made of polyvinyl alcohol resin on the base film (20). First, a primer layer (not shown) may be formed on the base film 20. The primer layer is formed by drying the coating solution for the primer layer applied on the base film (20).

The coating solution for a primer layer is, for example, a resin solution obtained by dissolving a powder of a resin forming the aforementioned primer layer in a solvent. Examples of the solvent for the coating solution for the primer layer include an organic solvent and an aqueous solvent capable of dissolving the above-mentioned resin. Examples of the organic solvent include aromatic hydrocarbons such as benzene, toluene and xylene; Ketones such as acetone, methyl ethyl ketone and methyl isobutyl ketone; Esters such as ethyl acetate and isobutyl acetate; Chlorinated hydrocarbons such as methylene chloride, trichlorethylene, and chloroform; And alcohols such as ethanol, 1-propanol, 2-propanol and 1-butanol. As the solvent of the coating solution for the primer layer, water is preferable. This is because the base film 20 is hard to dissolve irrespective of the material of the base film 20 and the influence on the environment can be reduced. The concentration of the resin in the coating solution for a primer layer is preferably 1% by mass or more and 25% by mass or less.

The method of applying the coating solution for the primer layer is not particularly limited as long as it is capable of applying the coating solution for the primer layer on the base film (20). Examples of the application method of the coating solution for the primer layer include a roll coating method such as a wire bar coating method, a reverse coating method and a gravure coating method, a die coating method, a comma coating method, a lip coating method, a screen coating method, a fountain coating method, Spray method, and the like.

Depending on each application method, a coating device for applying a coating solution for a primer layer can be selected.

The coated primer layer coating solution is dried using a drying furnace (not shown). In the drying furnace, heat is applied to the coating solution for the primer layer by, for example, spraying hot air, and the coating solution for the primer layer is dried and cured. Whereby a primer layer is formed.

The drying furnace for drying the coating solution for the primer layer is not particularly limited as far as it can dry the coating solution for the primer layer. The drying temperature in the drying furnace is, for example, 50 ° C or more and 200 ° C or less, preferably 60 ° C or more and 150 ° C or less. The drying temperature in the drying furnace can be appropriately set in accordance with the type of the solvent contained in the coating solution for the primer layer. When the solvent of the coating solution for the primer layer contains water, the drying temperature of the drying furnace is desirably 80 DEG C or higher. The drying time is, for example, about 30 seconds to 20 minutes or less.

After the primer layer is formed, the coating solution for the resin layer 33 is coated on the base film 20 through the primer layer by using the coating device 42. [ The coating solution 33 for a resin layer is, for example, a polyvinyl alcohol-based resin solution obtained by dissolving a polyvinyl alcohol-based resin powder in a solvent. The polyvinyl alcohol-based resin is the same as that described above in the description of the material for forming the polarizer 10.

The solvent of the coating solution 33 for the resin layer is, for example, water. The concentration of the polyvinyl alcohol resin in the coating solution 33 for a resin layer is preferably 5 mass% or more, more preferably 5 mass% or more and 15 mass% or less, still more preferably 5 mass% or more and 10 mass% or less Do. When the concentration of the polyvinyl alcohol-based resin in the coating solution 33 for the resin layer is less than 5% by mass, the ratio of the liquid component in the coating solution 33 for the resin layer becomes large, The efficiency of drying may be lowered. When the concentration of the polyvinyl alcohol-based resin in the coating solution 33 for the resin layer is 15 mass% or more, the viscosity of the coating solution 33 for the resin layer becomes excessively large and the coating solution 33 for the resin layer It may become difficult.

The viscosity of the coating solution 33 for a resin layer is set such that the thickness of the layer of the coating solution 33 for a resin layer which is easy to coat on the base film 20 and is formed on the base film 20 is unlikely to be uneven The range is not particularly limited. The viscosity of the coating layer 33 for a resin layer is preferably 0.5 Pa · s or more and 10 Pa · s or less, for example, and preferably 0.8 Pa · s or more and 7 Pa · s or less More preferably 1 Pa · s or more and 5 Pa · s or less.

When the viscosity of the coating layer 33 for a resin layer is less than 0.5 Pa · s, the applied coating layer 33 for resin layer flows and the thickness precision of the resin layer 34 may decrease. When the viscosity of the coating solution 33 for the resin layer is larger than 10 Pa · s, the filter that can be used in the coating device 42 for coating the coating solution 33 for the resin layer is limited, The quality of the resin layer 34 may deteriorate.

The viscosity of the coating solution 33 for a resin layer may be in the above-described range when it is applied onto the base film 20. The viscosity of the resin layer coating solution 33 may be out of the above range in a tank (not shown) for storing the resin layer coating solution 33 connected to the coating device 42 . In this case, for example, the viscosity of the resin layer coating liquid 33 can be set within the above-mentioned numerical range by heating or cooling the coating liquid 33 for the resin layer.

The coating solution 33 for a resin layer may contain additives such as a plasticizer and a surfactant. The kind of the plasticizer is as described above. The blending amount of the additive in the resin layer coating solution 33 is preferably 20% by mass or less based on the amount of the polyvinyl alcohol-based resin.

The method of applying the coating solution 33 for a resin layer using the coating device 42 is not particularly limited as long as it is capable of applying the coating solution 33 for a resin layer on the base film 20. As a method of applying the coating solution 33 for a resin layer using the coating device 42, the same method as the coating method of the coating solution for a primer layer described above can be mentioned. The coating method of the resin layer coating solution 33 using the coating device 42 may be the same as or different from the coating method of the coating solution for a primer layer. As the application device 42, an application device according to each application method can be appropriately selected. The thickness of the applied coating layer 33 for a resin layer is, for example, 50 m or more and 200 m or less.

Subsequently, the coating solution 33 for a resin layer coated on the base film 20 is dried using a drying furnace 52. Then, In the drying furnace 52, heat is applied to the layer of the coating solution 33 for the resin layer by, for example, sprayed hot air, and the coating solution 33 for the resin layer is dried and cured. Thus, a resin layer 34 is formed.

The drying furnace 52 is not particularly limited as long as it can dry the coating liquid 33 for a resin layer. The drying temperature in the drying furnace 52 is, for example, 50 占 폚 to 200 占 폚, preferably 60 占 폚 to 150 占 폚. The drying temperature in the drying furnace 52 can be suitably set in accordance with the type of the solvent contained in the coating solution 33 for the resin layer. When the solvent of the coating layer 33 for a resin layer contains water, the drying temperature of the drying furnace 52 is desirably 80 DEG C or higher. The drying time is, for example, about 2 minutes to about 20 minutes.

As described above, the resin layer 34 is formed, and the layered product 70 in which the base film 20, the primer layer, and the resin layer 34 are laminated in this order is formed. The thickness of the formed resin layer 34 is, for example, 3 mu m or more and 20 mu m or less, and preferably 5 mu m or more and 20 mu m or less.

The stretching step (S11b) is a step of stretching the resin layer (34) together with the base film (20). In the stretching step S11b, the layered product 70 is uniaxially stretched in the longitudinal direction by using the stretching device 60. [

Thus, the resin layer 34 is stretched. The thickness of the resin layer 34 is reduced by stretching.

The stretch magnification of the resin layer 34 can be appropriately selected in accordance with the polarization characteristics of the desired polarizer 10. The stretch magnification of the resin layer 34 is preferably greater than 5 times, preferably 17 times or less, more preferably 5 times, or 8 times or less the dimension in the longitudinal direction of the resin layer 34 before stretching . When the stretching magnification of the resin layer 34 is 5 times or less, the orientation of the resin layer 34 becomes insufficient and the polarization degree of the polarizer 10 to be produced may not be sufficiently increased. When the stretch ratio of the resin layer 34 is larger than 17 times, the multilayer body 70 is easily broken or the thickness of the multilayer body 70 is excessively small, so that the workability and handling property in the subsequent process There may be a case where it is lowered.

The stretching device 60 is not particularly limited as long as the resin layer 34 can be stretched at a predetermined stretching magnification. The stretching method of the layered product 70 using the stretching device 60 may be a roll-to-roll stretching method in which a difference in the main speed of the transporting roll is applied to perform the stretching, or tenter stretching may be used. Further, the stretching process may be performed in multiple steps. In this case, all of the stretching process in multiple steps may be performed before the dyeing step (S11c), or all or all of the elongating step after the second step may be performed in the dyeing step (S11c).

The drawing temperature at the time of drawing the laminate 70 (the resin layer 34) by using the stretching device 60 is set to be not lower than the temperature at which the base film 20 and the resin layer 34 show fluidity to such an extent that the base film 20 and the resin layer 34 can be stretched Respectively. The stretching temperature is preferably in the range of -30 DEG C to +30 DEG C of the phase transition temperature (melting point or glass transition temperature) of the base film 20, more preferably -30 DEG C to + 5 DEG C , More preferably in the range of -25 占 폚 to 占 0 占 폚. When the stretching temperature is lower than -30 占 폚 of the phase transition temperature of the base film 20, the base film 20 is too small in fluidity to stretch the base film 20 and the resin layer 34 in some cases. When the stretching temperature is higher than the phase transition temperature of + 30 占 폚 of the base film 20, the fluidity of the base film 20 is excessively large and the base film 20 and the resin layer 34 may not be stretched easily . When the base film 20 has multiple layers, the phase transition temperature of the base film 20 refers to the highest temperature among the phase transition temperatures of a plurality of layers.

The dyeing step (S11c) is a step of adsorbing the dichroic dye to the resin layer (34). In the dyeing step (S11c), the stretched laminate (70) is immersed in the dyeing solution (80) containing a dichroic dye. The dyeing solution (80) is a solution in which a dichroic dye is dissolved in a solvent. The solvent of the dyeing solution (80) is, for example, water. An organic solvent compatible with water may be added to the solvent of the dyeing solution (80) in addition to water. The concentration of the dichroic dye in the dyeing solution 80 is preferably 0.01 mass% or more and 10 mass% or less, more preferably 0.02 mass% or more and 7 mass% or less, more preferably 0.025 mass% or more and 5 mass% or less desirable.

When the dichroic dye is iodine, iodide is preferably added to the dye solution 80 containing iodine. This is because the dyeing efficiency can be improved. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide and titanium iodide. The concentration of iodide in the dyeing solution (80) is preferably 0.01 mass% or more and 20 mass% or less.

It is preferable to add potassium iodide even in iodide. When potassium iodide is added, the ratio of the mass of potassium iodide to the mass of iodine is preferably 5 or more and 100 or less, more preferably 6 or more and 80 or less, still more preferably 7 or more and 70 or less.

The time for immersing the layered product 70 in the dyeing solution 80 is not particularly limited, but is preferably 15 seconds or more and 15 minutes or less, and more preferably 1 minute or more and 3 minutes or less. The temperature of the dyeing solution 80 is preferably from 10 캜 to 60 캜, more preferably from 20 캜 to 40 캜.

By performing the above-described dyeing treatment, the polarizer 10 in which the oriented dichroic dye is adsorbed to the resin layer 34 and laminated on the base film 20 through the primer layer can be obtained. Thus, the polarizing laminate 71 in which the base film 20, the primer layer, and the polarizer 10 are laminated in this order can be obtained.

In addition, the dyeing step (S11c) may include a crosslinking treatment step which is carried out subsequent to the above-mentioned dyeing treatment. In the crosslinking treatment step, the entirety of the dyed laminate 70 is immersed in a crosslinking solution containing a crosslinking agent. Examples of the crosslinking agent include boron compounds such as boric acid and borax; Glyoxal; And glutaraldehyde. The crosslinking agent may be used alone or in combination of two or more.

As the crosslinking solution, a solution in which a crosslinking agent is dissolved in a solvent can be used. The solvent of the crosslinking solution is, for example, water. In addition to water, an organic solvent compatible with water may be added to the solvent of the crosslinking solution. The concentration of the crosslinking agent in the crosslinking solution is, for example, preferably 1% by mass or more and 20% by mass or less, more preferably 6% by mass or more and 15% by mass or less.

Iodide may be added to the crosslinking solution. By the addition of the iodide, the polarization characteristics in the plane of the resin layer 34 can be more uniform. Examples of the iodide added to the crosslinking solution include iodides such as iodide added to the dye solution 80 described above. The iodide added to the crosslinking solution and the iodide added to the dyeing solution 80 may be the same or different. The concentration of iodide in the cross-linking solution is preferably 0.05 mass% or more and 15 mass% or less, more preferably 0.5 mass% or more and 8 mass% or less.

The time for immersing the layered product 70 in the crosslinking solution is preferably from 15 seconds to 20 minutes, more preferably from 30 seconds to 15 minutes. The temperature of the crosslinking solution is preferably from 10 캜 to 80 캜.

The crosslinking treatment may be carried out simultaneously with the dyeing treatment by blending the crosslinking agent into the dyeing solution 80. [ The treatment of immersing in a crosslinking solution may be carried out two or more times using two or more crosslinking solutions having different compositions.

The absorption axis measuring step S11d is a step of measuring the angle of the absorption axis of the polarizer 10 with respect to a predetermined direction orthogonal to the lamination direction in which the polarizing film 1 and the retardation film 13 are laminated. In the present embodiment, the predetermined direction is, for example, the longitudinal direction (the transport direction, the lateral direction in Fig. 3). The angle of the absorption axis is measured using a measuring instrument 90. In this specification, the measuring instrument 90 is, for example, "KOBRA (registered trademark) -WPR" manufactured by Oji Paper Co., Ltd. and "RETS (registered trademark)" manufactured by Otsuka Denshi Co., The measuring instrument 90 measures the absorption axis of the polarizer 10 by receiving light emitted from the polarizer 10 and incident on the polarizing laminate 71 from the base film 20 side.

In the absorption axis measuring step S11d, the angles of the absorption axes of the polarizers 10 are measured at a plurality of positions along the width direction orthogonal to both the lamination direction and the longitudinal direction (the direction perpendicular to the paper surface of Fig. 3). As an example, as a measurement method in the absorption axis measuring step S11d, there is a method of measuring the angle of the absorption axis with respect to each part when the polarizer 10 is divided into three parts along the width direction have. In this case, for example, the three measurement points may be located at a position of 50 mm toward the center portion in the center portion in the width direction and both end portions in the width direction. In the present embodiment, the absorption axis measuring step S11d is set before the protective film splicing step S11e after the polarizer forming step S11f (the resin layer forming step (S11a) to the dyeing step S11c) .

The protective film bonding step (S11e) is a step of bonding the protective film (11) to the polarizer (10). The protective film 11 is bonded to the surface of the polarizer 10 opposite to the base film 20 (the surface on the upper side in Fig. 3) through the adhesive layer 12. Examples of the method of forming the adhesive layer 12 include a method of applying the forming material of the adhesive layer 12 to the surface of the polarizer 10 or a method of dropping the forming material of the adhesive layer 12 on the surface of the polarizer 10, A method in which an adhesive is spread on the surface of the substrate. Examples of the method of applying the forming material of the adhesive layer 12 include a roll coating method such as a wire bar coating method, a reverse coating method and a gravure coating method, a die coating method, a comma coating method, a lip coating method, a screen coating method, , Dipping method, and spray method.

The bonding method of the protective film 11 is not particularly limited. For example, the protective film 11 wound in a roll form is unwound and the protective film 11 is placed on the adhesive layer 12, and two protective films 11 sandwiching the protective film 11 and the polarizing laminated body 71 The protective film 11 can be bonded by passing between the rollers.

By the above process, a laminate in which the polarizing film 1 including the polarizer 10 and the protective film 11 are laminated on the base film 20 can be obtained. The base film 20 is peeled off from this laminate to obtain a polarizing film (1). A method for peeling off the base film 20 is not particularly limited, and for example, a method similar to the peeling process of a separator (peeling film) performed in a polarizing plate having a pressure-sensitive adhesive can be employed. The base film 20 may be peeled off immediately after the protective film bonding step S11e or may be peeled off from the protective film bonding step S11e after the protective film 11 is bonded to the polarizing layered body 71 Rolled into a roll, and peeled off in a subsequent step.

The polarizing film 1 produced as described above is wound around a core material and temporarily stored as a disk roll. Thus, the disk roll 101 (see Fig. 4) on which the strip-shaped polarizing film 1 is wound can be obtained. In the polarizing film preparing step (S11) of the present embodiment, a plurality of polarizing films (1) are formed and prepared as described above. Thereby, the master roll 101 of the plurality of polarizing films 1 can be obtained.

The phase difference film preparation step (S12) is a step of preparing the phase difference film (13). In the phase difference film preparation step (S12), for example, a disk roll 113 (see Fig. 4) in which a strip-shaped phase difference film 13 is wound is prepared. In the phase difference film preparation step (S12) of the present embodiment, a plurality of disc rolls (113) of the retardation films (13) are prepared.

The phase advance axis measuring step S13 is a step of measuring the angle of the fast axis of the phase difference film 13 with respect to the predetermined direction. The predetermined direction is the same as the predetermined direction based on the measurement of the angle of the absorption axis in the absorption axis measuring step S11d, for example, the longitudinal direction. The measuring device for measuring the angle of the fast axis can be selected in the same manner as the measuring device 90 for measuring the absorption axis of the polarizer 10, for example. The measuring device for measuring the angle of the fast axis may be the same as or different from the measuring device 90 for measuring the absorption axis.

The predetermined direction as a reference when measuring the angle of the absorption axis in the absorption axis measuring step S11d and the predetermined direction as a reference when measuring the angle of the fast axis in the fast axis measuring step S13 are, It is permissible to slightly differ from each other. That is, the predetermined direction as the reference of the angle in each measurement step is the same direction, which includes that the predetermined direction in each measurement step is substantially the same direction.

In the fast axis measuring step (S13), the angle of the fast axis of the phase difference film (13) is measured at a plurality of points along the width direction. As an example, as a method of measuring the angle of the fast axis in the fast axis measuring step S13, the angle of the fast axis is measured for each portion when the retardation film 13 is divided into three portions along the width direction Method. In this case, for example, the three measurement points may be located at a position of 50 mm toward the center portion in the center portion in the width direction and both end portions in the width direction. In the fast axis measuring step (S13) of the present embodiment, the fast axis is measured for each of the plurality of retardation films (13) prepared in the retardation film preparing step (S12).

The selection step (S14) is a step of selecting bonding surfaces mutually bonded from the polarizing film (1) and the retardation film (13) prepared in the above process. In the selection step S14, the respective bonding surfaces are selected such that the relative angle between the absorption axis and the fast axis is less than a predetermined angle in the portion where the polarizing film 1 and the retardation film 13 are bonded to each other. In the present embodiment, in a plurality of portions (a plurality of portions measured in the above-described respective measurement steps) among the portions bonded to each other in the polarizing film 1 and the retardation film 13, It is preferable to select each bonding surface so that the relative angle is less than the predetermined angle. The predetermined angle to be set is preferably 0.24 deg., More preferably 0.20 deg., And further preferably 0.15 deg.. By setting the predetermined angle to 0.24 degrees, the degree of polarization of the laminated film 100 to be produced can be further improved.

In the selection step (S14) of the present embodiment, the bonding surface of the polarizing film (1) is selected from both surfaces of the plurality of polarizing films (1). In the selection step (S14) of this embodiment, the bonding surface of the retardation film (13) is selected from both surfaces of the plurality of retardation films (13). That is, in the selection step (S14), the polarizing film (1) and the retardation film (13) bonded to each other in the subsequent phase difference film bonding step (S15) are bonded to each other in the plurality of polarizing films (1) And a bonding surface joined to the retardation film 13 in the selected polarizing film 1 and a bonding surface bonded to the polarizing film 1 in the selected retardation film 13 are respectively selected . Since the retardation film 13 is bonded to the surface opposite to the side on which the protective film 11 of the polarizer 10 of the polarizing film 1 is bonded in the present embodiment, The face is limited to one face. The method of selecting each film and each bonding surface will be described later in detail.

The phase difference film bonding step S15 is a step of bonding the bonding face of the retardation film 13 selected in the selection step S14 to the bonding face of the polarizing film 1 selected in the selection step S14. 4 is a perspective view showing the procedure of the phase difference film bonding step (S15).

4, in the phase difference film bonding step (S15), the polarizing film (1) is unwound from the original roll (101) of the polarizing film (1) obtained in the polarizing film preparing step (S11) The retardation film 13 is unwound from the original roll 113 of the retardation film 13 obtained in the step S12. The retardation film 13 is bonded to the polarizing film 1 while aligning the longitudinal direction of the polarizing film 1 and the longitudinal direction of the retardation film 13 while releasing each film. The polarizing film 1 and the retardation film 13 are bonded together by passing between rolls and being pressed against each other in the same manner as in the case of bonding the protective film 11 in the protective film bonding step S11e.

Although not shown, an adhesive layer 14 (see FIG. 1) is formed on the bonding surface of the retardation film 13, and the polarizing film 1 and the retardation film 13 are bonded to each other through the adhesive layer 14.

The method of forming the adhesive layer 14 is not particularly limited. For example, a method similar to that of the above-described adhesive layer 12 may be employed, or a pressure-sensitive adhesive may be used.

By the above process, the laminated film 100 including the polarizing film 1 and the retardation film 13 is produced.

Next, a selection method of each film and each bonding surface in the selection step (S14) will be described. 5 is a plan view showing the laminated film 100 in Fig. 6 is a perspective view showing another procedure of the phase difference film bonding step (S15) different from that of Fig. 7 is a plan view showing the laminated film 100 in Fig.

For example, first, a case where the polarizing film 1 and the retardation film 13 are bonded as shown in Fig. 4 will be considered. 4, the polarizing film 1 is loosened from the top side of the disk roll 101, and the phase difference film 13 is loosened from the top side of the disk roll 113. Fig. In the following description, releasing the film from the upper side of the original roll may be simply referred to as " preliminarily ".

4 shows a polarizing film 1 having a polarizing film outer side 1b on both sides of the polarizing film 1 that is turned on the outer side when the polarizing film 1 is wound around the polarizing film 1, The inner side surface 13a of the retardation film is bonded. 4, the outer surface 1b of the polarizing film 1 is the bonding surface of the polarizing film 1, and the inner surface 13a of the retardation film is the bonding surface of the retardation film 13. The polarizing film outer surface 1b is an upper surface 10b (see Fig. 1) opposite to the protective film 11 in the polarizer 10.

Here, in the polarizing film 1, in the absorption axis measuring step S11d, in the three portions divided in the width direction (Y-axis direction), i.e., in the first portion AD1, the second portion AD2 and the third portion AD3 The angle of the absorption axis of the absorption axis is measured. The first portion AD1, the second portion AD2, and the third portion AD3 are formed adjacently in this order along the width direction. In the posture of the polarizing film 1 shown in Fig. 4 and Fig. 5, the first portion AD1 is the left side in the width direction (-Y side) of the polarizing film 1 and the third portion AD3 is the polarizing film 1) side in the width direction (+ Y side). And the second portion AD2 is the widthwise central portion of the polarizing film 1. [

5 shows an example of the absorption axes A1, A2, and A3 in the in-plane parts of the polarizing film 1 by the broken-line arrows. The absorption axis A1 is the absorption axis of the first portion AD1 in the polarizing film 1. [ The absorption axis A2 is the absorption axis of the second portion AD2 in the polarizing film 1. [ The absorption axis A3 is the absorption axis of the third portion AD3 in the polarizing film 1. [

The angles of the respective absorption axes are set so that the angle of the absorption axis is set to a value in a direction counterclockwise from the upper side (+ Z side) to the lower side (-Z side) (hereinafter referred to as a plane) (+? Z side) is set as the positive side and the side (-θz side) facing the clockwise direction with respect to the longitudinal direction is set as the negative side.

The angle? A1 of the absorption axis A1 with respect to the longitudinal direction (X-axis direction) in the first portion AD1 is positive and the angle? A2 with respect to the longitudinal direction in the second portion AD2 is negative , And the angle? A3 of the absorption axis A3 with respect to the longitudinal direction in the third portion AD3 is positive.

The phase difference film 13 has three parts in the width direction (Y axis direction), i.e., the first part FD1, the second part FD2 and the third part FD3 in the fast axis measuring step S13 And the angle of the leading-end shaft of the motor is measured. The first portion FD1, the second portion FD2, and the third portion FD3 are formed adjacently in this order along the width direction. In the attitude of the retardation film 13 shown in Figs. 4 and 5, the first portion FD1 is the portion on the left in the width direction (-Y side) of the retardation film 13, (+ Y side) in the widthwise direction of the base 13. And the second portion FD2 is the center portion in the width direction of the retardation film 13. [

4 and 5, the first portion FD1 of the retardation film 13 is bonded to the first portion AD1 of the polarizing film 1 so as to oppose to the lamination direction (Z-axis direction). The second portion FD2 of the retardation film 13 is bonded to the second portion AD2 of the polarizing film 1 so as to oppose to the lamination direction. The third portion FD3 of the retardation film 13 is bonded to the third portion AD3 of the polarizing film 1 so as to oppose the lamination direction.

5 shows an example of the fast axes F1, F2 and F3 in the in-plane parts of the retardation film 13 by solid arrows. The fast axis F1 is the fast axis of the first portion FD1 of the retardation film 13. [ The fast axis F2 is the fast axis of the second portion FD2 in the retardation film 13. [ The fast axis F3 is the fast axis of the third portion FD3 in the retardation film 13. [

Similarly to the angle of each absorption axis described above, the angle of each fast axis is set such that the side (+? Z side) facing the counterclockwise direction with respect to the longitudinal direction (X axis direction) The side (-θz side) facing clockwise is set as the minus side.

The angle? F1 of the fast axis F1 with respect to the longitudinal direction (X axis direction) of the first portion FD1 is negative and the angle? F2 of the fast axis F2 with respect to the longitudinal direction of the second portion FD2 is positive , And the angle? F3 of the fast axis F3 with respect to the longitudinal direction in the third portion FD3 is negative.

The laminated film 100 has three portions divided in the width direction (Y axis direction), i.e., a left portion LD, a center portion CD, and a right portion RD. The left portion LD, the center portion CD, and the right portion RD are formed adjacently in this order along the width direction. 4 and 5, the left portion LD is formed by laminating the first portion AD1 of the polarizing film 1 and the first portion FD1 of the retardation film 13. The central portion CD is formed by stacking a second portion AD2 of the polarizing film 1 and a second portion FD2 of the retardation film 13. [ The right portion RD is formed by laminating the third portion AD3 of the polarizing film 1 and the third portion FD3 of the retardation film 13.

The relative angle between the absorption axis and the fast axis in the case where the polarizing film 1 and the retardation film 13 are bonded as shown in Fig. 4 is evaluated. Specifically, it is determined whether the relative angle between the absorption axis and the fast axis is less than a predetermined angle (for example, 0.24 degrees in this embodiment) in the left portion LD, center portion CD and right portion RD of the laminated film 100 Or not.

5, the relative angle? L in the left portion LD is a relative angle between an angle? A1 of the absorption axis A1 and an angle? F1 of the fast axis F1, and? L = |? A1- Loses. The relative angle? C in the central portion CD is a relative angle between an angle? A2 of the absorption axis A2 and an angle? F2 between the fast axis F2 and? C = |? A2-? F2 |. The relative angle? R in the right portion RD is a relative angle between an angle? A3 of the absorption axis A3 and an angle? F3 between the fast axis F3 and? R = |? A3 -? F3 |.

In the selection step S14 of the present embodiment, it is determined that the deviation between the absorption axis and the fast axis of the laminated film 100 is sufficiently small when the relative angles? L,? C, and? R are both less than the predetermined angle (0.24 degrees).

Here, for example, in the laminated film 100 in which the polarizing film 1 and the retardation film 13 are bonded together as shown in Figs. 4 and 5, the relative angles? L,? C, ). In this case, in the selection step (S14), the joining surface of the polarizing film (1) and the joining surface of the retardation film (13) are selected such that the joining surfaces are the combinations shown in Fig. 4 and Fig. That is, the outer surface 1b of the polarizing film is selected as the bonding surface of the polarizing film 1, and the inner surface 13a of the retardation film is selected as the bonding surface of the retardation film 13.

On the other hand, in the selection step S14 of the present embodiment, when any one or more of the relative angles? L,? C, and? R is equal to or larger than the predetermined angle (0.24 degrees), the displacement of the absorption axis and the phase- It is judged to be big.

Here, for example, in the laminated film 100 formed by bonding the polarizing film 1 and the retardation film 13 as shown in Figs. 4 and 5, at least one of the relative angles? L,? C, (0.24 DEG) or more. In this case, the combination of the joint surfaces different from the combination shown in Figs. 4 and 5 is examined again.

In the case of another examination, for example, a case of joining the polarizing film 1 and the retardation film 13 as shown in Fig. 6 will be considered. In Fig. 6, the polarizing film 1 is produced as in Fig. The disk roll 113 is set in an inverted posture in the width direction (Y axis direction) with respect to the posture of the disk roll 113 in Fig. 4, . 6 and 7, the retardation film 13 has a width direction (Y-axis direction) and a stacking direction (Z-axis direction) with respect to the posture of the retardation film 13 shown in FIG. 4 and FIG. To the polarizing film 1 in a reversed posture.

In the following description, unfolding the film from the lower side of the original roll is simply referred to as " downstream ".

In Fig. 6, the outer surface 1b of the polarizing film is bonded to the outer surface 13b of the retardation film 13 which is the outer side of the outer surface of the retardation film 13 when it is wound on the disk roll 113. That is, in Fig. 6, the junction face of the retardation film 13 is the outer face 13b of the retardation film, unlike the junction face in Fig. The bonding surface of the polarizing film 1 is the polarizing film outer surface 1b similarly to Fig.

6 and 7, the retardation film 13 is in a posture inverted in the width direction (Y axis direction) with respect to the posture of the retardation film 13 shown in Figs. 4 and 5 have. 6 and 7, the first portion FD1 is a portion on the right side in the width direction (+ Y side) of the retardation film 13, and the third portion FD3 is a portion on the retardation film 13 Direction-left side (-Y side). As in Figs. 4 and 5, the second portion FD2 is a widthwise central portion of the retardation film 13. Fig.

6 and 7, the first portion FD1 of the retardation film 13 is bonded to the third portion AD3 of the polarizing film 1 so as to face the lamination direction (Z-axis direction). The second portion FD2 of the retardation film 13 is bonded to the second portion AD2 of the polarizing film 1 so as to oppose the lamination direction. The third portion FD3 of the retardation film 13 is bonded to the first portion AD1 of the polarizing film 1 so as to oppose the lamination direction. That is, in the case of Figs. 6 and 7, the portion of the polarizing film 1 to which the first portion FD1 and the third portion FD3 of the retardation film 13 are bonded differs from the example of Fig. 4 and Fig.

6 and 7, the left portion LD of the laminated film 100 is formed by laminating the first portion AD1 of the polarizing film 1 and the third portion FD3 of the retardation film 13. The right portion RD is formed by stacking a third portion AD3 of the polarizing film 1 and a first portion FD1 of the retardation film 13. [ As in the case of Fig. 4 and Fig. 5, the central portion CD is formed by laminating the second portion AD2 of the polarizing film 1 and the second portion FD2 of the retardation film 13.

6 and 7, the retardation film 13 is in a posture inverted in the lamination direction (Z-axis direction) with respect to the posture of the retardation film 13 shown in Figs. 4 and 5 have. Therefore, as shown in Fig. 7, the slopes of the fast axes F1 to F3 are reversed in the width direction (Y-axis direction) from the case shown in Fig. That is, the angle? F1 of the fast axis F1 with respect to the longitudinal direction (X axis direction) of the first portion FD1 is positive and the angle? F2 of the fast axis F2 with respect to the longitudinal direction of the second portion FD2 is And the angle? F3 of the fast axis F3 with respect to the longitudinal direction in the third portion FD3 is positive.

The relative angle between the absorption axis and the fast axis in the case where the polarizing film 1 and the retardation film 13 are joined as shown in Fig. 6 is evaluated. Specifically, it is determined whether the relative angle between the absorption axis and the fast axis is less than a predetermined angle (for example, 0.24 degrees in this embodiment) in the left portion LD, center portion CD and right portion RD of the laminated film 100 Or not.

7, the relative angle? L in the left portion LD is a relative angle between an angle? A1 of the absorption axis A1 and an angle? F3 between the fast axis F3 and? L = |? A1-? F3 |. The relative angle? C in the central portion CD is a relative angle between an angle? A2 of the absorption axis A2 and an angle? F2 between the fast axis F2 and? C = |? A2-? F2 |. The relative angle? R in the right portion RD is a relative angle between an angle? A3 of the absorption axis A3 and an angle? F1 between the fast axis F1 and? R = |? A3 -? F1 |.

Here, in the example of FIG. 5, the angle of each absorption axis and the angle of each fast axis are opposite to each other in positive / negative directions in either the left portion LD, the center portion CD, or the right portion RD of the laminated film 100 Therefore, the relative angle between the absorption axis and the fast axis in each part tends to be comparatively large.

On the other hand, in the example of Fig. 7, the phase difference film 13 is inverted in the width direction (Y axis direction) and the lamination direction (Z axis direction) In the left portion LD and the right portion RD, the portion of the retardation film 13 overlapping with the polarizing film 1 is also changed. As a result, in the example of Fig. 7, the plus / minus of the angles of the respective absorption axes and the plus / minus of the angles of the fast axes coincide with each other in the left portion LD, the center portion CD and the right portion RD of the laminated film 100 . Therefore, in the example of Fig. 7, the relative angle between the absorption axis and the fast axis in each part of the laminated film 100 is smaller than that in the example of Fig.

7, the angle? A3 of the absorption axis A3 and the angle? F1 of the fast axis F1 are the same, and the absorption axis A3 and the fast axis F1 are superimposed on each other. That is, in the example of FIG. 7, the relative angle? R in the right portion RD is 0 占.

For example, in the laminated film 100 formed by joining the polarizing film 1 and the retardation film 13 as shown in Figs. 6 and 7, when the relative angles? L,? C, and? R are both less than a predetermined angle (0.24 deg. . In this case, in the selection step (S14), the joining surface of the polarizing film (1) and the joining surface of the retardation film (13) are selected such that the joining surface is the combination shown in Fig. 6 and Fig. That is, the outer surface 1b of the polarizing film is selected as the bonding surface of the polarizing film 1, and the outer surface 13b of the retardation film is selected as the bonding surface of the retardation film 13.

On the other hand, for example, in the laminated film 100 formed by bonding the polarizing film 1 and the retardation film 13 as shown in Figs. 6 and 7, at least one of the relative angles? L,? C, (0.24 DEG) or more. In this case, the combination of bonding surfaces different from the combination shown in Figs. 6 and 7 is further examined. In the case of further examination, for example, at least one of the polarizing film 1 and the retardation film 13 is changed to another film, and the bonding surfaces are examined as described above.

Thus, the polarizing film 1 and the retardation film 13 are selected so that the respective relative angles? L,? C and? R are less than a predetermined angle (0.24 °) in the laminated film 100 to be formed, Is selected.

4 to 7, for convenience of explanation, the polarizing film 1 and the retardation film 13 are bonded to each other in the laminated film 100, And the angle was evaluated. However, in the actual selection step S14, the absorption in each part obtained from the absorption axis measuring step S11d and the phase advancing axis measuring step S13, without joining the polarizing film 1 and the retardation film 13, From the angle data of the axis and the angle data of the fast axis, selection of each film and selection of each joint surface is performed.

According to the present embodiment, based on the angle data of the absorption axis and the angle data of the fast axis obtained from the absorption axis measuring step S11d and the fast axis measuring step S13, the relative angle between the absorption axis and the fast axis A selection step S14 for selecting a surface is set. Therefore, in the phase difference film bonding step (S15), the bonding surfaces selected in the selection step (S14) are bonded to each other so that the relative angle between the absorption axis and the fast axis is less than the predetermined angle, ) Can be bonded. Thus, in the obtained laminated film 100, the relative angle between the absorption axis of the polarizing film 1 and the fast axis of the retardation film 13 can be made small, and the absorption axis and the fast axis can be prevented from being tilted. Therefore, the laminated film 100 excellent in the degree of polarization can be obtained. Thus, according to the present embodiment, when the laminated film 100 is used for a liquid crystal display device, the contrast of the liquid crystal display device can be suppressed from being lowered.

As another method for suppressing the deviation between the absorption axis and the fast axis, for example, there is a method of rotating the polarizing film 1 and the retardation film 13 around an axis parallel to the stacking direction and adjusting the angle of the absorption axis and the angle of the fast axis A method of bonding the films together is conceivable. However, in this method, since the joining angle between the polarizing film 1 and the retardation film 13 is displaced, it is not possible to use a method of joining the films unwound from the roll to each other as in the present embodiment, It is difficult to obtain a film.

Further, for example, as another method for suppressing the deviation between the absorption axis and the fast axis, the polarizing film 1 and the retardation film 13 are cut so that the displacement between the absorption axis and the fast axis when the polarizing film 1 and the retardation film 13 are joined together in the longitudinal direction , And a method of modifying the shape of each film to be joined may be considered. However, in this method, there is a problem in that the production cost of the laminated film is increased because the film is cut. Further, similarly to the above-mentioned other methods, it is difficult to obtain a long laminated film. Further, even if a long laminated film is obtained, there is a problem that the dimension in the width direction is reduced by cutting the film.

With respect to these methods, according to the present embodiment, the joining angle of the polarizing film 1 and the retardation film 13, which have been made long, is not displaced and the shape of the film is not corrected by cutting the film, It is possible to obtain a long polarizing film 1 by aligning the films together. Therefore, the manufacturing cost of the laminated film 100 can be suppressed from increasing, and a long laminated film 100 can be obtained easily. Also, the dimension in the width direction of the laminated film 100 can be suppressed from being reduced. From this point of view, the production method of this embodiment is more effective when producing a laminated film having a length in the longitudinal direction of 100 m or more, and is more effective when producing a laminated film having a length in the width direction of 30 cm or more.

Further, for example, when an original roll of a polarizing film is produced, if the angle of the absorption axis is greatly deviated from the fast axis of the retardation film to be bonded, desired properties can not be obtained as a laminated film to be produced. For this reason, for example, there is a case where a prepared polarizing film is discarded and a disk roll of a polarizing film is newly produced. As a result, there is a problem that the produced polarizing film is useless and the yield of the laminated film is lowered.

On the other hand, according to the present embodiment, since the selection step S14 is set, by selecting the junction surface of the retardation film having the fast axis with little deviation from the absorption axis of the produced polarizing film 1, Can be suppressed from becoming useless. As a result, the yield of the laminated film 100 can be suppressed from being lowered.

According to the present embodiment, in the selecting step S14, the respective bonding surfaces are selected such that the relative angle of the angle of the absorption axis to the angle of the fast axis is less than 0.24 DEG. Therefore, in the laminated film 100 to be produced, the distortion between the absorption axis and the fast axis can be suitably suppressed, and the degree of polarization of the laminated film 100 can be suitably improved.

In addition, when the angle of the absorption axis of the polarizer 10 measured in the absorption axis measuring step S11d is deviated from a desired angle, it is difficult to obtain desired performance for the polarizing film 1 to be produced. In this case, there is a problem that the width of a product which can use the polarizing film 1 becomes narrow.

On the other hand, according to the present embodiment, the absorption axis measuring step S11d is set after the polarizer forming step S11f and before the protective film splicing step S11e. Therefore, when the angle of the absorption axis of the polarizer 10 measured in the absorption axis measuring step S11d is greatly deviated from the desired angle, the conveyance of the polarizer 10 is stopped and the bonding of the protective film 11 is stopped can do. Thereby, the polarizer 10 in a state where the protective film 11 is not bonded can be obtained. Therefore, it is possible to change the kind of the film to be bonded to the polarizer 10, and to prevent the narrowing of the width of the product that can use the polarizing film or other multilayer film to be produced.

According to the present embodiment, in the phase difference film preparation step (S12), a plurality of phase difference films (13) are prepared, and in the selection step (S14) (13). Therefore, it is possible to increase the number of combinations of the bonding surfaces of the retardation film 13 bonded to the bonding surface of the polarizing film 1. Thus, in the obtained laminated film 100, the relative angle between the absorption axis of the polarizing film 1 and the fast axis of the retardation film 13 can be made smaller. Therefore, the degree of polarization of the laminated film 100 can be further improved. From this point of view, the number of the retardation films to be prepared in the phase difference film preparing step (S12) is preferably 2 or more, more preferably 3 or more.

According to the present embodiment, in the polarizing film preparing step S11, a plurality of polarizing films 1 are prepared, and in the selecting step S14, (1). Therefore, it is possible to increase the number of combinations of the joining surfaces of the polarizing film 1 and the joining surfaces of the retardation film 13. Thus, in the obtained laminated film 100, the relative angle between the absorption axis of the polarizing film 1 and the fast axis of the retardation film 13 can be made smaller. Therefore, the degree of polarization of the laminated film 100 can be further improved. From this point of view, the number of polarizing films to be prepared in the polarizing film preparation step (S11) is preferably two or more, more preferably three or more.

Further, by selecting the combination of the plurality of polarizing films 1 and the plurality of retardation films 13 in this way, it is possible to suppress the increase of the deviation between the absorption axis and the fast axis and the failure to obtain desired characteristics. Therefore, it is possible to further suppress the polarizing film (1) or the retardation film (13) from being wasted. Therefore, it is possible to further suppress the reduction in the yield of the laminated film (100).

If the relative angle between the absorption axis and the fast axis is not less than a predetermined angle in a part of the polarizing film (1) and the retardation film (13) prepared in one preparation step, the original roll of the film is stored And can be used as a film to be prepared in the next preparation step. This makes it possible to further prevent the polarizing film (1) or the retardation film (13) from being wasted.

As described above, in the case of the present embodiment, since the protective film 11 is bonded to one surface of the polarizing film 1, the surface that can be selected as the bonding surface with respect to one polarizing film 1 is protected And only the polarizing film outer surface 1b opposite to the film 11 is present. However, by changing the bonding surface of the retardation film 13, the relative angle between the absorption axis and the fast axis can be changed, and practically, the number of combinations for selecting the bonding surface is not reduced.

When the retardation film 13 can be bonded to both surfaces of the polarizing film 1, the bonding surface of the polarizing film 1 is bonded to the polarizing film outer surface 1b and both surfaces of the polarizing film 1, And can be selected from the inside surface 1a of the polarizing film which becomes the inside when the original roll 101 is wound. In this case, the degree of freedom in selecting the joining method of the polarizing film 1 and the retardation film 13 can be increased.

According to the present embodiment, the angle of the absorption axis is measured at a plurality of positions in the width direction of the polarizer 10 in the absorption axis measuring step S11d and the angle of the absorption axis is measured at the front side of the phase difference film 13 The angle of the fast axis is measured at a plurality of positions in the width direction. Then, in the selection step (S14), the phase difference film (13) is bonded to the polarizing film (1) such that the relative angle between the absorption axis and the fast axis is less than a predetermined angle at a plurality of positions. Therefore, the relative angle between the absorption axis of the polarizing film 1 and the fast axis of the phase difference film 13 can be reduced at a plurality of positions in the width direction of the laminated film 100, and the polarization degree of the laminated film 100 Can be improved.

In the present embodiment, the following method may be employed.

In the selection step S14, the direction in which the joining faces of the respective films are joined may be selected such that the relative angle between the absorption axis and the fast axis is less than a predetermined angle. In this case, in the phase difference film bonding step (S15), the bonding face of the retardation film (13) is bonded to the bonding face of the polarizing film (1) based on the bonding direction selected in the selection step (S14). The direction in which the joining faces of the respective films are joined includes, for example, the direction in the longitudinal direction of the joining face. Hereinafter, this will be described in detail.

For example, as shown in Figs. 4 and 6, when the films are joined together using the disc roll 101 of the polarizing film 1 and the disc roll 113 of the retardation film 13 as they are, The posture of each film is not reversed in the longitudinal direction in any of the case where the film is transported and the case where the film is transported downward. However, by rewinding the original roll, the posture of the film can be reversed in the longitudinal direction. In this case, since the distribution of the absorption axis or the fast axis in the width direction can be regarded as being uniform in the longitudinal direction, only the posture of the film can be reversed in the longitudinal direction.

8A to 8C are explanatory diagrams for explaining rewinding of a disk roll. 8A to 8C show a case where the original roll 101 of the polarizing film 1 is wound again.

As shown in Fig. 8A, one end 1c in the longitudinal direction of the polarizing film 1 is unwound from the disk roll 101 and wound on another core member as shown in Fig. 8B. Thus, the rewound disc roll 201 can be obtained. As shown in Fig. 8C, the rewound roll 201 is the end of the polarizing film 1 on the side where the other end 1d in the longitudinal direction is unwound.

When the master roll 201 of the polarizing film 1 obtained as described above is produced as shown in Figs. 4 and 6, the front and back of the polarizing film 1 are oriented in the longitudinal direction The direction in which the polarizing film outer surface 1b, which is the bonding surface of the polarizing film 1, can be reversed can be reversed. In this case, since the posture of the polarizing film 1 is also reversed in the width direction, the portion of the polarizing film 1 to which the first portion FD1 and the third portion FD3 of the retardation film 13 are bonded is the same as that shown in Figs. This is different from the case of the example of Fig. Specifically, a portion of the retardation film 13 bonded to the first portion FD1 and the third portion FD3 is opposite between the first portion AD1 and the third portion AD3 of the polarizing film 1.

On the other hand, in this case, the bonding surface of the polarizing film 1 is the same polarizing film outer surface 1b as in Figs. 4 and 6, and the orientation of the polarizing film 1 does not reverse in the laminating direction. Therefore, the plus / minus of the angle of the absorption axis of the polarizing film 1 is the same as that shown in Figs. 4 and 6. Thus, by changing the direction of the bonding surface of the polarizing film 1, it is possible to change the bonding portion between the polarizing film 1 and the retardation film 13 without changing the plus / minus of the angle of the absorption axis, The relative angle of the axis can be changed.

As described above, according to this method, by selecting the direction in which the joining faces of the respective films are joined in the selection step S14, the absorption axis and the phase axis of the phase axis film 13 can be obtained by using the same polarizing film 1 and the phase difference film 13. [ The width for changing the relative angle can be widened. Concretely, two combinations of the same polarizing film (1) and the retardation film (13) to change the joining surface without detecting the roll of the disc, and the combination of two It is possible to change the relative angle between the absorption axis and the fast axis in a total of four combinations. Therefore, in the selection step (S14), the joining conditions for joining the respective films in the retardation film joining step (S15) can be more appropriately selected. As a result, the lowering of the degree of polarization of the laminated film 100 can be further suppressed. Further, the polarizing film 1 and the phase difference film 13, which are prepared in plural, can be efficiently used in combination, and the production efficiency of the laminated film 100 can be improved.

In the above example, the case where the original roll 101 of the polarizing film 1 is wound again is described, but the present invention is not limited to this. The original roll 113 of the retardation film 13 may be wound again to change the joining direction of the joining face of the retardation film 13.

In the polarizing film preparation step (S11), the method of forming the polarizing film (1) is not particularly limited. For example, the polarizing film 1 may be formed by a method of producing a film of a polyvinyl alcohol-based resin by extrusion molding, followed by a stretching treatment and a dyeing treatment.

In the polarizing film preparing step (S11), the polarizing film (1) may not be formed, or a plurality of polarizing films (1) previously formed may be prepared. In the polarizing film preparing step S11, only one polarizing film 1 may be prepared. In addition, only one phase difference film 13 may be prepared in the phase difference film preparation step (S12). In addition, only one polarizing film 1 may be prepared in the polarizing film preparing step S11, and only one phase difference film 13 may be prepared in the phase difference film preparing step S12. In this case, each film to be bonded in the phase difference film bonding step (S15) is inevitably determined. By selecting the bonding direction of each bonding face and each bonding face, it is possible to suppress the decrease in polarization degree of the produced laminated film 100 have.

Further, the protective film bonding step (S11e) may not be provided. Further, in place of the protective film bonding step (S11e), or in addition to the protective film bonding step (S11e), a process of bonding other films or the like may be set.

In the absorption axis measuring step S11d, the absorption axis may be measured at two or four or more positions. Further, in the fast axis measuring step (S13), the fast axis may be measured at two points or at four or more points. For example, when the respective axes are measured at two points, the respective joint surfaces may be selected so that the relative angles of the respective axes at the two measured positions are smaller than a predetermined angle in the selection step (S14). In addition, for example, when the respective axes are measured at four or more points, even if the respective joint surfaces are selected so that the relative angles of the respective axes are less than a predetermined angle at all of the four or more positions measured in the selection step (S14) good.

In the absorption axis measuring step S11d, the absorption axis may be measured at only one position. Further, in the fast axis measuring step (S13), the fast axis may be measured at only one position. In this case, in the selection step (S14), the respective bonding surfaces may be selected so that the relative angles of the respective axes at a single measured position are less than a predetermined angle.

As described above, in the present specification, the selection of the joint surfaces so that the relative angles of the respective axes are less than the predetermined angle in the selection step (S14) means that, at all points measured in each measurement step, And selecting each joint surface such that the relative angle is less than a predetermined angle.

The predetermined direction, which is a reference for measuring the angle of the absorption axis and the angle of the fast axis, may be a direction other than the longitudinal direction.

The absorption axis of the polarizer 10 is orthogonal to the transmission axis of the polarizer 10. Therefore, measuring the absorption axis of the polarizer 10 is equivalent to measuring the transmission axis of the polarizer 10. Further, the fast axis of the retardation film 13 is orthogonal to the slow axis of the retardation film 13. Therefore, measuring the fast axis of the retardation film 13 is equivalent to measuring the slow axis of the retardation film 13. That is, evaluating the relative angle between the absorption axis and the fast axis by measuring the absorption axis and the fast axis respectively is equivalent to evaluating the relative angle between the transmission axis and the slow axis by measuring the transmission axis and the slow axis respectively. Therefore, a step of measuring the transmission axis of the polarizer 10 may be provided instead of the absorption axis measuring step S11d, and a step of measuring the slow axis of the retardation film 13 may be provided instead of the fast axis measuring step S13.

In the resin layer forming step (S11a), a step of subjecting the surface of the base film (20) coated with the coating solution for primer layer to corona treatment may be performed before forming the primer layer. In the resin layer forming step (S11a), a primer layer may not be formed.

When a plasticizer is used to form the resin layer 34 in the resin layer forming step (S11a), the plasticizer may be removed before the dyeing step (S11c). The removal of the plasticizer is performed by, for example, dipping the laminate 70 in water at a temperature from room temperature to 70 deg. C or less to swell the laminate 70, thereby eluting the plasticizer from the laminate 70. [

When the crosslinking treatment is carried out in the dyeing step S11c, after the crosslinking treatment, the polarizing laminate 71 is immersed in water such as pure water, ion-exchanged water, distilled water, tap water, etc., It may be subjected to washing treatment. The water washing liquid may contain iodide. Then, thereafter, the processing of drying the polarization-controlling multilayer body 71 may be performed. As the drying treatment, known methods such as natural drying, heat drying, air drying, and vacuum drying may be employed.

The dyeing step (S11c) may be performed before the drawing step (S11b), or the dyeing step (S11c) and the drawing step (S11b) may be performed at the same time.

≪ Second Embodiment >

The second embodiment differs from the first embodiment in the position where the absorption axis measuring process is performed.

Note that the same constitution as that of the above-described embodiment may be omitted by omitting the same reference numerals as appropriate.

Fig. 9 is a flow chart showing the procedure of the manufacturing method of the laminated film 100 of the present embodiment. 9, the manufacturing method of the laminated film 100 of the present embodiment includes a polarizing film preparing step (S21), an absorption axis measuring step (first measuring step) (S22), a retardation film preparing step (S12), a fast axis measuring step (S13), a selecting step (S14), and a retardation film bonding step (S15).

The polarizing film preparing step (S21) is the same as the polarizing film preparing step (S11) of the first embodiment, except that the absorption axis measuring step (S11d) is not set.

The absorption axis measuring step S22 is set after the polarizing film preparing step S21 and before the selecting step S14. In the absorption axis measuring step S22, the absorption axis of the polarizer 10 in the polarizing film 1 obtained in the polarizing film preparing step S21 is measured. The measurement of the absorption axis is carried out using a measuring instrument such as "KOBRA (registered trademark) -WPR" manufactured by Oji Paper Co., Ltd., "RETS (registered trademark)" manufactured by Otsuka Denshi Co., The measuring device measures the absorption axis of the polarizer 10 by, for example, receiving the light that is incident on the polarizing film 1 from the side of the protective film 11 and emitted from the polarizer 10.

According to the present embodiment, the absorption axis measuring step S22 is set after the polarizing film preparing step S21. Therefore, even when the angle of the absorption axis in the protective film joining step (S11e), for example, is changed, the angle of the absorption axis after the error can be measured in the absorption axis measuring step (S22). Therefore, the angle of the absorption axis immediately before the phase difference film 13 is bonded can be measured, and the bonding surface can be more appropriately selected in the selection step S14. As a result, the degree of polarization of the laminated film 100 can be further improved.

In the above embodiment, the direction of the absorption axis in the polarizer 10 is aligned with the direction of the fast axis in the retardation film 13, but the present invention is not limited to this. For example, the direction of the absorption axis in the polarizer 10 and the direction of the slow axis in the retardation film 13 may be matched. In this case, instead of the fast axis measuring step S13, a slow axis measuring step (first measuring step) for measuring the angle of the slow axis of the retardation film 13 with respect to the predetermined direction is provided. In the selection step S14, the polarization film 1 and the retardation film 13 are bonded to each other so that the relative angle between the absorption axis and the slow axis becomes less than a predetermined angle, ) And the phase difference film (13). Even when the absorption axis and the slow axis are matched, the degree of polarization of the laminated film 100 can be improved by making the relative angle between the axes less than a predetermined angle (for example, 0.24 degrees).

In addition, the above-described methods in the first embodiment and the second embodiment can be combined with each other within a range not inconsistent.

[Example]

Examples were produced using the production method of the laminated film 100 of each of the above-described embodiments, and the usefulness of the present invention was confirmed.

In the examples, the base film was a non-stretched polypropylene film having a thickness of 90 탆. The melting point of the base film was 163 ° C. The tensile modulus in the longitudinal direction of the base film was 205 MPa at 80 캜.

The coating solution for the primer layer in the examples was prepared as follows. Polyvinyl alcohol powder ("Z-200" manufactured by Nippon Gohsei Kagaku Kogyo K.K., average molecular weight 1100, average saponification degree: 99.5 mol%) was dissolved in hot water at 95 ° C to prepare a polyvinyl alcohol aqueous solution having a concentration of 3% . A coating solution for a primer layer was prepared by mixing 1 part by mass of a crosslinking agent ("Sumirez Resin (registered trademark) 650" manufactured by Sumitomo Chemical Co., Ltd.) with respect to 2 parts by mass of polyvinyl alcohol.

The coating liquid for the resin layer in the examples was prepared as follows. A polyvinyl alcohol powder ("PVA 124" manufactured by Kabushiki Kaisha Kuraray Co., Ltd., average degree of polymerization: 2400, average degree of saponification: 98.0 mol% or more, not more than 99.0 mol%) was dissolved in hot water at 95 캜 and a polyvinyl alcohol aqueous solution , And this was used as a coating solution for a resin layer.

The substrate film obtained as described above was continuously conveyed, corona treatment was performed on one surface thereof, and the above-mentioned coating solution for a primer layer was continuously applied to the corona-treated surface using a microgravure coater (coating device) . The applied primer layer coating solution was dried in a first drying device at 60 占 폚 for 3 minutes to form a primer layer having an average thickness of 0.2 占 퐉.

While the base film on which the primer layer was formed was continuously conveyed, the above-mentioned coating solution for resin layer was continuously coated on the primer layer using a lip coater (coating device). The applied coating solution for the resin layer was dried at 80 캜 for 8 minutes by using a drying device to form a resin layer on the primer layer.

The film was stretched in the longitudinal direction (film transport direction) by a stretching method between nip rolls while continuously transporting a laminate having a primer layer and a resin layer formed on a base film. The stretching was divided into two stages. Initially, the film was stretched until the stretching magnification was 2.5 times at a stretching temperature of 140 占 폚, and then stretching was performed at a stretching temperature of 160 占 폚 until the stretching magnification became 5.8 times. Here, the drawing magnification is a magnification with respect to the dimension in the longitudinal direction of the laminate in an unstretched state. That is, in the drawing step of this embodiment, the laminate was stretched so that the draw ratio finally became 5.8 times.

The stretched laminate was continuously conveyed and immersed in a dyeing solution containing iodine and potassium iodide at a temperature of 30 DEG C for a residence time of about 150 seconds to dye the resin layer. The excess dyeing solution was washed away with pure water at 10 DEG C and then the laminate was immersed in a crosslinked solution containing boric acid and potassium iodide at 76 DEG C for a residence time of 600 seconds and crosslinked. Thereafter, the laminate was washed with pure water at 10 캜 for 4 seconds, and dried at 80 캜 for 300 seconds. Thus, a polarizer in which the oriented dichroic dye was adsorbed on the resin layer was obtained.

The same treatment as described above was also applied to the surface opposite to the surface of the base film on which the polarizer was formed to form a polarizer. Thus, a polarizing laminate having a polarizer laminated on both surfaces of a base film through a primer layer was obtained. Three such polarizing laminates were produced. These three polarizing laminated bodies are referred to as a first polarizing laminate, a second polarizing laminate, and a third polarizing laminate, respectively.

The angle of the absorption axis of the polarizer with respect to the first and second polarizing laminated films was measured. In measuring the angle of the absorption axis, the polarizer formed on one surface of the base film was peeled off and the angle of the absorption axis with respect to the polarizer left on the base film was measured. Light (wavelength: 590 nm) was incident on the polarizing laminate from the base film side, and light transmitted through the polarizer was received to measure the angle of the absorption axis. For measurement of the angle of the absorption axis, " KOBRA (registered trademark) -WPR " manufactured by Oiso Kikai Kikai Co., Ltd. was used. The angle of the absorption axis was measured with respect to the center portion in the width direction of the polarizing laminate, that is, the second portion and both side portions in the width direction of the polarizing laminate, namely, the first portion and the third portion.

The measurement point in the first part is a part that is 40 mm x 40 mm in the width direction and the length direction centering on a position of 50 mm from the end on one side in the width direction to the other side in the width direction of the polarizing laminate did. The measurement points in the second portion were defined as a portion having a width of 40 mm x 40 mm in the width direction and the longitudinal direction centering on the center position in the width direction of the polarizing laminate. The measurement points in the third portion are portions 40 mm x 40 mm in the width direction and the length direction centering on a position of 50 mm from one end in the width direction to the other end in the width direction of the polarizing laminate did. Each measurement point of each part was measured once, and the average value was defined as the angle of the absorption axis in each part.

The adhesive solution was coated on the polarizer while continuously conveying the polarizing laminate for each of the first and second polarizing laminated films measured for the absorption axis to form an adhesive layer. A triacetylcellulose (TAC) film ("KC4UY" manufactured by Konica Minolta Optics, Inc., thickness: 40 μm), to which a bonding surface was saponified, was bonded to a polarizer through an adhesive layer. As a bonding method, a method in which a polarizing laminate is passed between a pair of rolls in a state in which a TAC film (protective film) is adhered to the polarizer through an adhesive layer, and then pressed.

The adhesive solution was prepared as follows. Polyvinyl alcohol powder ("KL-318" manufactured by Kabushiki Kaisha Kuraray Co., Ltd., average degree of polymerization: 1800) was dissolved in hot water at 95 ° C to prepare a polyvinyl alcohol aqueous solution having a concentration of 3% by mass. The obtained aqueous solution was mixed with a crosslinking agent (Sumirez Resin (registered trademark) 650 manufactured by Sumitomo Chemical Co., Ltd.) at a ratio of 1 part by mass based on 2 parts by mass of polyvinyl alcohol to obtain an adhesive solution.

The base film was peeled off from the first polarizing laminate and the second polarizing laminate to which the TAC film was bonded to obtain a first polarizing film and a second polarizing film. The obtained first polarizing film and second polarizing film were each wound on a core material to form a disk roll.

With respect to the third linearly polarizing laminated body, the TAC film was bonded in the same manner as the above-mentioned first and second polarizing laminated bodies. In the third linearly polarizing laminate, TAC films were bonded to both surfaces of the polarizing laminate. Thereafter, the third polarizing laminate was separated between the base film and one of the polarizers, and the base film was peeled off from the polarizing laminate having the base film to obtain a third polarizing film. The obtained third polarizing film was wound on a core material to form a disk roll.

The angle of the absorption axis of the polarizer with respect to the third polarizing film was measured. In measuring the angle of the absorption axis, light (wavelength: 590 nm) was incident on the third polarizing film, and light passing through the polarizer was received to measure the angle of the absorption axis. For measurement of the angle of the absorption axis, " KOBRA (registered trademark) -WPR " manufactured by Oiso Kikai Kikai Co., Ltd. was used. The angle of the absorption axis was measured with respect to the central portion in the width direction of the third polarizing film and both side portions in the width direction of the third polarizing film, that is, from the first portion to the third portion. The measurement points of the first to third portions of the third polarizing film were the same as those of the first to third portions in the first and second polarizing laminated bodies.

For each of the first polarizing film, the second polarizing film and the third polarizing film, the thickness of the polarizer was 5.3 mu m.

Table 1 shows the measured angle [degrees] of the absorption axis of each polarizing film. The angle of the absorption axis shown in Table 1 is the angle of the absorption axis in the polarizing film posture in the case where it is inverted in the same manner as shown in Fig.

[Table 1]

In Table 1, the visual sensitivity correction polarization degree [%] of each polarizing film is also shown. The visual sensitivity correction polarization degree was calculated as follows. First, light having a predetermined wavelength was incident on a Glanth Thompson prism, and the transmittance of the polarizing film with respect to the polarized light emitted from Glanth Thompson prism was measured. For the measurement of transmittance, a spectrophotometer (V7100, manufactured by Nippon Bunko K.K.) having an integrating sphere was used. The transmittance is a ratio of the amount of light (amount of light received by the measuring instrument) of the light that has passed through the object to be measured, to the total light amount (in this case, the total light amount of polarized light emitted from the Glen Thomson prism) emitted from the light source.

As the transmittance, the MD transmittance and the TD transmittance were measured respectively. The MD transmittance is a transmittance when the polarization direction of the polarized light emitted from the Glan Thompson prism is parallel to the direction of the transmission axis of the polarizing film. The TD transmittance is the transmittance when the polarization direction of the polarized light emitted from the Glanthampton prism is orthogonal to the direction of the transmission axis of the polarizing film. The measured MD transmittance and TD transmittance were substituted into the following equation (2) to calculate the polarization degree.

[Equation 1]

Here, the values of the MD transmittance and the TD transmittance substituted in (Equation 2) are values obtained by averaging the transmittances measured with respect to each of the cases where light having wavelengths of 380 nm or more and 780 nm or less is incident on the Glan-Thompson prism did.

The visual acuity correction was performed on the degree of polarization calculated by the above formula (2) by the visual field of 2 degrees (C light source) of JIS Z 8701 to obtain the visual sensitivity correction polarization degree. At this time, in this specification, the visual sensitivity correction polarization degree is simply referred to as the polarization degree.

Subsequently, two disc rolls of a cycloolefin-based transversely stretched retardation film (Zeonoa Film (registered trademark) manufactured by Nippon Zeon Co., Ltd.) were prepared as a retardation film. The two retardation films are referred to as a first retardation film and a second retardation film. The fast axis was measured for each of the first retardation film and the second retardation film. The angle of the fast axis was measured in the same manner as the polarizing film described above using " KOBRA (registered trademark) -WPR " manufactured by Oji Paper Co., The measurement results are shown in Table 2. The angle [deg.] Of the fast axis shown in Table 2 is the angle of the fast axis in the retardation film posture as shown in Fig.

[Table 2]

From the measurement data of the absorption axes of the three polarizing films obtained as described above and the measurement data of the fast axis of the two retardation films, the combination in which the relative angle is less than 0.24 deg. The results are shown in Tables 3 to 8.

[Table 3]

[Table 4]

[Table 5]

[Table 6]

[Table 7]

[Table 8]

Table 3 shows the case where the first polarizing film and the first retardation film are bonded to each other. Table 4 shows the case where the first polarizing film and the second retardation film are bonded. Table 5 shows the case where the second polarizing film and the first retardation film are bonded to each other. Table 6 shows the case where the second polarizing film and the second retardation film are bonded. Table 7 shows the case where the third polarizing film and the first retardation film are bonded. Table 8 shows the case where the third polarizing film and the second retardation film are bonded to each other.

In each of Tables 3 to 8, the case where the winding state of the polarizing film in the original roll is the winding state as it was and the case where the winding state is reversed in the longitudinal direction as shown in Figs. 8A to 8C In the case of the above-described embodiment. In both cases, the case where the phase difference film is changed as shown in Fig. 4 and the case where the phase difference film is changed as shown in Fig. 6 are shown. The polarizing film was unwound by any method.

The angle data shown in the above Tables 1 and 2 are the angle data in the case where the polarizing film and the retardation film are jointly joined together in a state of being in a winding state as the winding state of the polarizing film is made as shown in Fig. to be. That is, when the winding state of the polarizing film is in a winding state as it is, and the method of unwinding the polarizing film and the method of unwinding the retardation film are both preliminary, the relative angle of the left- Is the absolute value of the difference between the angle of the absorption axis of the first part in the first part and the angle of the fast axis of the first part in the table 2. The relative angle of the right portion in the laminated film is the absolute value of the difference between the angle of the absorption axis of the third portion in Table 1 and the angle of the fast axis of the third portion in Table 2. [

When the method of loosening the retardation film is taken as the outline, the attitude of the retardation film is reversed in the width direction and the stacking direction. Therefore, in Tables 3 to 8, the angle of the fast axis is changed in the left portion and the right portion, and the plus / minus is reversed with respect to the values shown in Table 2.

When the winding state of the polarizing film is rewound and inverted, the attitude of the polarizing film is reversed in the width direction and the length direction. Therefore, in Tables 3 to 8, the angle of the absorption axis is changed in the left portion and the right portion. In this case, since the attitude of the polarizing film is not reversed in the lamination direction, the plus / minus of the absorption axis is not changed with respect to the values shown in Table 1. [

The center portion of the laminated film is not described in Tables 3 to 8 because the relative angle is less than 0.24 deg. In any combination described above.

In Table 3 to Table 8, the portions indicated by hatching are portions where the relative angle is less than 0.24 deg. In either the central portion, the left portion, or the right portion of the laminated film. Among them, by selecting the direction in which the respective joining faces and joining faces are joined and joining the respective films, it is possible to obtain a laminated film in which the distortion between the absorption axis and the fast axis is small and the decrease in the degree of polarization is suppressed.

The laminated films of Examples 1 to 6 were produced by selecting from the combinations shown in Tables 3 to 8 in which relative angles were less than 0.24 deg. Further, a laminated film of Comparative Examples 1 to 4 was produced by selecting from a combination in which the relative angle was 0.24 or more in at least one of the left side portion and the right side portion shown in Tables 3 to 8.

In Example 1, the winding state of the polarizing film was manufactured as it was, and the third polarizing film and the first retardation film were bonded together in advance.

In Example 2, the release state of the polarizing film was prepared as it was, and the third polarizing film and the second retardation film were bonded together in advance.

In Example 3, the unrolling state of the polarizing film was rewound and inverted to manufacture the first polarizing film in advance and the second retardation film in the outward direction.

In Example 4, the unwinding state of the polarizing film was rewound so as to be inverted, and the first polarizing film was produced and the first retardation film was bonded at the outward.

In Example 5, the unrolling state of the polarizing film was rewound so as to be in an inverted state, and the second polarizing film was produced in advance and the first retardation film was bonded in the outward direction.

In Example 6, the unwinding state of the polarizing film was rewound so as to be in an inverted state, and the second polarizing film was produced in advance and the second phase difference film was bonded in the outward direction.

In Comparative Example 1, the release state of the polarizing film was prepared as it was, and the first polarizing film and the second retardation film were bonded together in advance.

In Comparative Example 2, the release state of the polarizing film was prepared as it was, and the second polarizing film and the second retardation film were bonded together in advance.

In Comparative Example 3, the release state of the polarizing film was prepared as it was, and the second polarizing film and the first retardation film were bonded together in advance.

In Comparative Example 4, the unwinding state of the polarizing film was rewound and inverted, and the third polarizing film was produced and the second phase difference film was bonded at the outward.

In each of the Examples and Comparative Examples, the polarizing film and the retardation film were bonded in the following manner. First, an ultraviolet ray-curable adhesive (" KR-75T ", manufactured by ADEKA Corporation) was coated on the bonding surface of the retardation film using a small diameter gravure coater so that the thickness after curing became about 1.0 mu m. 4 and 6, a pair of nip rolls was used to press the retardation film onto the polarizing film through the UV curable adhesive. A UV-curable adhesive was cured by irradiating the pressed film with ultraviolet light at an integrated light quantity of 200 mJ / cm < 2 > on the retardation film side using a high-pressure mercury lamp. Thus, laminated films of the respective Examples and Comparative Examples were obtained. Each laminated film thus prepared was in the form of a long belt, and the dimension in the longitudinal direction was 500 m. Each laminated film was formed by a roll of a core wound on a core material.

With respect to each of the examples and comparative examples obtained as described above, light was incident on the retardation film side to measure the visibility correction polarized light intensity. The results are shown in Tables 9 and 10.

[Table 9]

[Table 10]

It can be seen from Tables 9 and 10 that, in Examples 1 to 6, the visibility correction polarization degree is not less than 99.992% in the central portion, the left portion, and the right portion, whereas in Comparative Examples 1 to 4, It was confirmed that the visual sensitivity correction polarization degree was less than 99.992% in one or both of the parts. Empirically, when the visual sensitivity correction polarization degree is 99.992% or more, a sufficiently high contrast can be obtained when the laminated film is used in a liquid crystal display device.

Therefore, according to this embodiment, it was confirmed that by setting the selection step, a laminated film excellent in the degree of polarization (visual sensitivity correction polarization degree) can be produced. It has also been confirmed that the use of the thus-produced laminated film can suppress the lowering of the contrast of the liquid crystal display device. Further, it was confirmed that a laminated film having an excellent degree of polarization and a long elongation was easily obtained.

Thus, the usefulness of the present invention can be confirmed.

1: polarizing film
10: Polarizer
11: Protective film
13: retardation film
100: laminated film
101, 113, 201: disk roll
A1, A2, A3: absorption axis
F1, F2, F3:
S11, S21: Polarizing film preparing process
S11d, S22: absorption axis measuring step (first measuring step)
S11e: Protective film bonding step
S11f: Polarizer formation step
S12: Preparing phase difference film
S13: phase advancing axis measuring step (second measuring step)
S14: Selection process
S15: Phase difference film bonding process

Claims (11)

A method for producing a laminated film comprising a polarizing film comprising a polarizer in which a dichroic dye is oriented in a polyvinyl alcohol-based resin, and a retardation film bonded to the polarizing film,
A polarizing film preparation step of preparing the polarizing film;
A phase difference film preparing step of preparing the phase difference film,
A first measurement step of measuring an angle of an absorption axis of the polarizer with respect to a predetermined direction orthogonal to a lamination direction in which the polarizing film and the retardation film are laminated,
A second measuring step of measuring an angle of the fast axis of the retardation film with respect to the same direction as the predetermined direction based on the measurement of the angle of the absorption axis in the first measuring step;
A junction surface mutually bonded from the polarizing film and the retardation film is selected so that a relative angle between the absorption axis and the fast axis is less than a predetermined angle in a portion where the polarizing film and the retardation film are bonded to each other, ,
And a phase difference film joining step of joining the joining face of the retardation film to the joining face of the polarizing film,
The polarizing film is unwound from a disk roll in which the strip-shaped polarizing film is wound and the retardation film is unwound from a disk roll on which the strip-shaped retardation film is wound, And the longitudinal direction of the retardation film are aligned so that the retardation film is bonded to the polarizing film. A method for producing a laminated film comprising a polarizing film comprising a polarizer in which a dichroic dye is oriented in a polyvinyl alcohol-based resin, and a retardation film bonded to the polarizing film,
A polarizing film preparation step of preparing the polarizing film;
A phase difference film preparing step of preparing the phase difference film,
A first measurement step of measuring an angle of an absorption axis of the polarizer with respect to a predetermined direction orthogonal to a lamination direction in which the polarizing film and the retardation film are laminated,
A second measurement step of measuring an angle of a phase axis of the retardation film with respect to a direction same as the predetermined direction based on the measurement of the angle of the absorption axis in the first measurement step;
Wherein the polarizing film and the retardation film are bonded to each other so that a relative angle between the absorption axis and the retardation axis is less than a predetermined angle, ,
And a phase difference film joining step of joining the joining face of the retardation film to the joining face of the polarizing film,
The polarizing film is unwound from a disk roll in which the strip-shaped polarizing film is wound and the retardation film is unwound from a disk roll on which the strip-shaped retardation film is wound, And the longitudinal direction of the retardation film are aligned so that the retardation film is bonded to the polarizing film. The method for producing a laminated film according to claim 1 or 2, wherein the predetermined angle is 0.24 DEG. 3. The method according to claim 1 or 2, wherein in the selecting step, a direction in which the joining surfaces are joined is selected so that the relative angle is less than the predetermined angle,
And the bonding surface of the retardation film is bonded to the bonding surface of the polarizing film on the basis of the bonding direction selected in the phase difference film bonding step. The method according to claim 1 or 2, wherein the polarizing film preparation step is a polarizing film forming step of forming the polarizing film,
In the polarizing film forming step,
A polarizer forming step of forming the polarizer,
And a protective film bonding step of bonding a protective film to the polarizer,
Wherein the first measuring step is performed after the polarizer forming step and before the protective film bonding step. The method for producing a laminated film according to claim 1 or 2, wherein the first measurement step is performed after the polarizing film preparation step and before the selection step. The method according to claim 1 or 2, wherein in the step of preparing the retardation film, a plurality of the retardation films are prepared,
In the selecting step, the bonding surface of the retardation film is selected from both surfaces of the plurality of retardation films. The method according to claim 1 or 2, wherein in the polarizing film preparing step, a plurality of polarizing films are prepared,
In the selection step, the bonding surface of the polarizing film is selected from both surfaces of the plurality of polarizing films. The method according to claim 1 or 2, wherein in the first measurement step, measurements are made at a plurality of points along the width direction of the polarizing film,
In the second measurement step, measurements are made at a plurality of points along the width direction of the retardation film,
In the selection step, the bonding surfaces are selected so that the relative angle is less than the predetermined angle at a plurality of positions of the portions to be bonded to each other in the mutually opposing polarizing film and the retardation film . The method according to claim 1 or 2, wherein the polarizing film preparation step comprises:
A step of preparing a laminate in which the polarizing film is laminated on a base film,
And the first measurement step of measuring an angle of the absorption axis of the polarizer in a state in which the polarizing film is laminated on the base film,
Further comprising a step of peeling the polarizing film from the base film before the step of bonding the phase difference film after the first measuring step. The liquid crystal display device according to claim 10, wherein the laminate has the polarizer formed on both surfaces of the base film,
Further comprising a step of peeling the polarizer formed on one side of the base film before the first measurement step,
Wherein the angle of the absorption axis of the polarizer on the side left on the base film is measured in the first measurement step.

Images