JP2018169480A - Method for manufacturing retardation film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a retardation film capable of suppressing axis deviation distribution of a liquid crystal compound.SOLUTION: A method for manufacturing a retardation film comprises the steps of: forming a first coating film on a continuous film support body to be conveyed by applying and drying an alignment layer forming material; forming an alignment layer by irradiating the first coating film with polarized ultraviolet light; forming a second coating film on the alignment layer by applying and drying a liquid crystal layer forming material; and forming a liquid crystal layer by aligning and fixing the liquid crystal compound in the second coating film. The alignment layer forming step winds the continuous film support body 50 in which the first coating film is formed around a temperature-adjustable backup roll 40, and irradiates the first coating film with polarized ultraviolet light. The polarized ultraviolet light is obtained by polarizing the light emitted from a bar-like light source 10 with a wire grid polarizer 30. The alignment layer forming step arranges a wire grid 34 of the wire grid polarizer 30 at an angle θ vertical to or not parallel to a longitudinal direction X of the backup roll 40, and installs a louver 20 between the bar-like light source 10 and the wire grid polarizer 30.SELECTED DRAWING: Figure 2

Description

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

  As a retardation film or a viewing angle compensation film used for a liquid crystal display or the like, a film in which an alignment layer and a liquid crystal layer are provided on a support is known. The alignment layer is a film for arranging the liquid crystal compounds of the liquid crystal layer in a certain direction, and an alignment treatment is applied to the coating film containing an alignment factor to provide alignment regulating force. The liquid crystal compounds in the liquid crystal layer formed on the alignment layer are regularly arranged according to the alignment of the alignment layer.

  As the orientation treatment, a rubbing method in which a roller wound with a cloth such as nylon is rotated while being pushed into a substrate with a constant pressure has been widely used. However, there is a problem that fine dust and static electricity are generated due to the friction of the substrate, and in recent years, a photo-alignment system that applies alignment regulation force by irradiating polarized light has been used.

  For example, Patent Document 1 discloses a photo-alignment device including a light guide unit that is formed of a substantially rectangular plate having a non-reflective film on a surface provided between a rod-shaped lamp and a substrate at regular intervals in the longitudinal direction of the rod-shaped lamp. It is disclosed. Further, Patent Document 2 discloses a polarized light irradiation device for photo-alignment provided with a rod-shaped lamp and a wire grid polarizer. Further, Patent Document 3 includes a light irradiation unit including a linear light source and a wire grid polarizer, and a light irradiation polarized light irradiation provided with a mechanism for rotating the light irradiation unit about an axis orthogonal to the alignment film. An apparatus is disclosed.

JP 2014-26133 A JP 2004-144484 A JP 2006-133498 A

  The irradiation method described in the above-mentioned patent document is a method in which a support on which a coating film for an alignment layer is formed is transported on a flat plate to irradiate polarized light, or there is no flat plate between a feeding roll and a winding roll. Irradiation is carried out with a support suspended. In any case, a conveyance tension is applied, and the support may have wrinkles or the like on the flat plate, and the support may flutter up and down when the support is suspended between rolls (so-called, Fluttering). In such a case, there is a problem that the irradiation of polarized light is not performed uniformly and the photo-alignment is not performed uniformly.

  Therefore, the present inventors can irradiate polarized light without wrinkles or fluttering by wrapping a support on a backup roll and irradiating on the backup roll, thereby improving the axial variation of the liquid crystal compound. I thought. When the transmission axis direction of the wire grid polarizer is perpendicular or parallel to the longitudinal direction of the backup roll, the incident angle of the polarized light will not change even if it is projected on the backup roll by applying light from an oblique direction or light from the front. No. However, for the purpose of providing a pretilt angle (a rising angle of the liquid crystal) of the liquid crystal compound, there is a case where polarized light is irradiated obliquely with an incident angle with respect to the alignment layer. In such a case, if the transmission axis has an angle with respect to the longitudinal direction of the backup roll, the angle at which the light in front of the projection is projected is equal to the transmission axis angle. Is projected at a different angle. In this case, there is a problem that the alignment angle of the liquid crystal compound changes and an axial shift distribution of the liquid crystal compound occurs.

  The present invention has been made in view of the above circumstances, and in a retardation film in which an alignment layer and a liquid crystal layer are provided on a support, the retardation film suppresses the occurrence of an axial displacement distribution of a liquid crystal compound. An object is to provide a manufacturing method.

The method for producing the retardation film of the present invention comprises:
A step of forming a first coating film by applying and drying an alignment layer forming material for forming an alignment layer having an alignment regulating force for a liquid crystal compound on a continuous film support to be conveyed;
A step of forming an alignment layer by irradiating polarized ultraviolet light to the first coating film to form an alignment layer; and applying and drying a liquid crystal layer forming material containing a liquid crystal compound on the alignment layer Forming a coating film of
Aligning the liquid crystal compound in the second coating film, fixing the alignment and forming a liquid crystal layer;
A method for producing a retardation film comprising:
The step of forming the alignment layer is to irradiate polarized ultraviolet light by winding the continuous film support on which the first coating film is formed around a temperature-controllable backup roll,
Polarized ultraviolet light is a light emitted from a rod-shaped light source and polarized with a wire grid polarizer,
The wire grid of the wire grid polarizer is arranged at an angle θ that is not perpendicular to or parallel to the longitudinal direction of the backup roll, and the light emitted from the rod light source is transmitted to the wire grid polarizer between the rod light source and the wire grid polarizer. A louver composed of a plurality of parallel plates arranged in the longitudinal direction of a backup roll for guiding light is installed.

  Here, “the angle θ not perpendicular or parallel to the longitudinal direction of the backup roll” means an angle that is neither perpendicular nor parallel to the longitudinal direction X of the backup roll in FIG. The terms “vertical” and “parallel” here are defined in consideration of the design accuracy and installation accuracy of the mechanical device.

  The diameter of the backup roll is preferably 2000 mm or less.

It is preferable that the angle θ of the wire grid and the pitch L (mm) of the louvers satisfy the following relationship.
L × (sin θ + 1) <40, where 0 <θ <90 °

In the method for producing a retardation film of the present invention,
In a plane perpendicular to the axis of the backup roll,
A line that passes through the axis of the backup roll and is perpendicular to the substrate surface of the wire grid polarizer is used as a reference line.
The angle formed by the reference line and the line connecting the axial center of the backup roll and the upstream end in the transport direction of the irradiation region of polarized ultraviolet light on the continuous film support is θ1,
When the angle formed by the reference line and the line connecting the axial center of the backup roll and the downstream end in the conveying direction of the irradiation region of the polarized ultraviolet light on the continuous film support is θ2, the relationship of the following formula is satisfied. preferable.
| Θ1-θ2 | <5 °

  According to the method for producing a retardation film of the present invention, it is possible to suppress the occurrence of an axial displacement distribution of a liquid crystal compound.

FIG. 1 is a processing flow of the method for producing a retardation film of the present invention. FIG. 2 is a schematic configuration diagram showing a process of forming an alignment layer. FIG. 3 is a top view showing the louver. FIG. 4 is a plan view showing the arrangement of the wire grid of the wire grid polarizer. FIG. 5 is a schematic view showing an angle adjustment mechanism of the wire grid polarizer. FIG. 6 is a schematic diagram illustrating an example of the arrangement of polarizing elements in a wire grid polarizer. FIG. 7 is a schematic diagram illustrating another example of the arrangement of polarizing elements in a wire grid polarizer. FIG. 8 is a diagram for explaining the irradiation angle. FIG. 9 is a schematic view showing a case where the transmission axis of the wire grid polarizer is parallel to the longitudinal direction X of the backup roll. FIG. 10 is a schematic view showing a case where the transmission axis of the wire grid polarizer is perpendicular to the longitudinal direction X of the backup roll.

  Hereinafter, an embodiment of a method for producing a retardation film of the present invention will be described with reference to the drawings. In FIG. 1, the processing flow of the manufacturing method of the retardation film of this invention is shown. The schematic block diagram which shows the formation process of the orientation layer in the retardation film of this invention in FIG. 2 is shown.

[Method for producing retardation film]
In the method for producing a retardation film of the present invention, as shown in FIG. 1, an alignment layer forming material for forming an alignment layer having an alignment regulating force for a liquid crystal compound is applied on a continuous film support to be conveyed. And drying to form a first coating film,
A step of forming an alignment layer by irradiating polarized ultraviolet light to the first coating film to form an alignment layer; and applying and drying a liquid crystal layer forming material containing a liquid crystal compound on the alignment layer Forming a coating film of
Aligning the liquid crystal compound in the second coating film, fixing the alignment and forming a liquid crystal layer;
Is a method for producing a retardation film.

  And the manufacturing method of the retardation film of this invention has the following characteristics in the process of forming an orientation layer. This will be described with reference to FIG.

That is, in the step of forming the alignment layer, the continuous film support 50 on which the first coating film is formed is wound around the backup roll 40 capable of adjusting the temperature and irradiated with polarized ultraviolet light.
The polarized ultraviolet light is obtained by polarizing the ultraviolet light emitted from the rod-shaped light source 10 with the wire grid polarizer 30, and the wire grid 34 of the wire grid polarizer 30 is perpendicular to the longitudinal direction X of the backup roll 40 or A louver 20 composed of a plurality of parallel plates 21 arranged in the longitudinal direction X of the backup roll 40 is installed between the rod-shaped light source 10 and the wire grid polarizer 30 and arranged at an angle θ that is not parallel. At this time, the 1st coating film is arrange | positioned at the rod-shaped light source 10 side.

  When the transmission axis of the wire grid polarizer 30 is tilted on a curved surface such as a backup roll, light from an oblique direction enters in a region deviated from the front of the backup roll. If it does so, the light from diagonal will be projected on the angle which shifted | deviated from the transmission axis. According to the present invention, by installing the louver 20 between the rod-shaped light source 10 and the wire grid polarizer 30, the wire grid 34 of the wire grid polarizer 30 is not perpendicular or parallel to the longitudinal direction X of the backup roll 40. Even if they are arranged at an angle θ, it is possible to suppress light incident on the support from an oblique direction. That is, light can be irradiated on the backup roll from the front.

A concave reflecting mirror 11 that covers a part of the rod-shaped light source 10 is provided on the upper portion of the rod-shaped light source 10. Thereby, the light emitted from the rod-shaped light source 10 can be efficiently reflected to the wire grid polarizer 30 side in the vertical direction.
Examples of the rod-shaped light source 10 include a high-pressure mercury lamp and a metal halide lamp. Alternatively, a plurality of lamps or light emitting diodes may be arranged in a straight line to form a rod shape.
The diameter of the backup roll is preferably 2000 mm or less. By being 2000 mm or less, since the support can be prevented from floating on the backup roll and deformation of the support can be suppressed, variations in the orientation axis can be suppressed. On the other hand, the lower limit of the diameter of the backup roll is not particularly limited as long as it has a sufficient thickness to transport the film.

(louver)
As shown in FIG. 3, the parallel plate 21 is arranged with a pitch L (mm) in the longitudinal direction X of the backup roll 40, and the louver 20 is arranged between the rod-shaped light source 10 and the wire grid polarizer 30. The By installing the louver 20, the light from the rod-shaped light source 10 can be converted into parallel light, the spread of the light incident on the wire grid polarizer 30 can be suppressed, and the light from the front can be made to the backup roll. Moreover, although the parallel plate 21 is arrange | positioned at the angle orthogonal to the longitudinal direction X of a backup roll in FIG. 3, you may arrange | position not only orthogonally but parallel to the diagonal direction. The parallel plate 21 can be adjusted in pitch and angle by an interlocking mechanism (not shown).
Although FIG. 3 shows the case where the louver 20 is composed of parallel plates arranged in the longitudinal direction of the backup roll 40, the configuration of the louver 20 is not limited to this. It may be composed of a plurality of cylindrical parts having a polygonal or circular cross section, and the central axis of the cylinder may be arranged in a direction perpendicular to the central axis of the backup roll, and has a non-reflective film on the surface constituting the cylinder. May be.
The louver is preferably installed as close as possible to the lamp so as not to leak light from the louver. In order to suppress light leakage, the louver and the lamp may be brought into contact with each other, or the gap may be shielded with another member. The same applies to the gap between the louver and the wire grid polarizer.

  The louver material can have a heat resistant material such as stainless steel or aluminum. The surface of the louver can be smoothed to improve the reflectance in order to improve the efficiency of irradiation light. Further, in order to improve the straightness of irradiation light, surface irregularities can be imparted, or the reflectance can be reduced by covering with a non-reflective film. When reducing the reflectance, it is preferable that a light absorbing member is provided on the surface of the parallel plate 21 of the louver 20.

(Wire grid polarizer)
As shown in FIG. 4, the wire grid polarizer 30 includes a plurality of wire grid polarization elements 32 held by a frame 31. Each wire grid polarization element 32 is formed by arranging wire grids 34 made of a plurality of linear electric conductors on a substrate 33 at an angle θ that is not perpendicular or parallel to the longitudinal direction X of the backup roll 40. The wire grid polarization element 32 reflects the polarization (polarization) component parallel to the longitudinal direction of the wire grid 34 and passes the orthogonal polarization (polarization) component. The direction passing through orthogonal polarization components is called the transmission axis.
Examples of the electric conductor include metal wires such as chromium and aluminum.

  In the wire grid polarizing element 32 of the present invention, the wire grid 34 is arranged at an angle θ that is not perpendicular or parallel to the longitudinal direction of the backup roll, as shown in FIG.

(Relationship between wire grid angle θ and louver pitch L)
In the present invention, the angle θ of the wire grid 34 and the pitch L (mm) of the louvers preferably satisfy the relationship of the following formula.
L × (sin θ + 1) <40, where 0 <θ <90 °.

By setting L × (sin θ + 1) <40, the orientation of the alignment layer can be made uniform, and the axial displacement of the liquid crystal compound formed thereafter can be reduced.
L × (sin θ + 1) is more preferably 20 or less.
In addition, when the pitch of the louvers is not uniform, it is preferable that the maximum pitch satisfies the relationship of the above formula.

  As shown in FIG. 9 and FIG. 10, when the transmission axis T of the wire grid polarizer 30 is parallel to the longitudinal direction of the backup roll, the oblique light or the light from the front is applied and projected onto the backup roll. However, if the wire grid has an angle θ with respect to the longitudinal direction of the backup roll, the oblique light is projected at an angle different from the angle θ. That is, the liquid crystal light distribution angle changes to generate an axial distribution. However, by making the relationship satisfying the above expression, light from an oblique direction can be suppressed.

-Wire grid angle adjustment method-
Here, a method for adjusting the angle of the wire grid 34 of the wire grid polarizing element in the present invention will be described with reference to FIG.
As shown in FIG. 5, the angle adjustment mechanism 60 includes a light source 61, a reference wire grid polarization element 63, and a polarization light receiving unit 65. The polarized light receiving unit 65 includes a light receiving element 66 that detects polarized light 67. A polarizer unit 64 for adjusting the angle of the wire grid is installed between the reference wire grid polarization element 63 and the polarization light receiving unit 65 to adjust the angle of the wire grid.

  Light 62 from the light source 61 passes through the reference wire grid polarization element 63, is polarized, and enters the polarizer unit 64. At this time, in the polarized light receiving unit 65, the light receiving element 66 receives the light that has passed through the reference wire grid polarizing element 63 as detection light. The positions of the reference wire grid polarizing element 63 and the polarizer unit 64 may be reversed.

As the light source 61, a UV (ultraviolet) lamp, a laser, a light emitting diode, a high-intensity discharge (HID) lamp, or the like can be used.
Further, as the light receiving element 66, an illuminometer, a photodiode, a photomultiplier tube, a photoelectric tube, or the like can be used.

  As the reference wire grid polarization element 63, any polarizer can be used as long as it is a linear polarizer. The shape of the reference wire grid polarizing element 63 may be any shape of a rectangular parallelepiped, a parallelogram, or a circle.

  The polarizer unit 64 is configured to be rotatable within a detection measurement range of 180 ° or more with the normal direction S as the rotation axis. The rotation of the polarizer unit 64 is determined by a preset rotation angle θs from the detection position P0.

  When the rotation angle θs of the polarizer unit 64 is an angle at which the direction of the transmission axis T1 of the reference wire grid polarization element 63 coincides with the direction of the transmission axis T2 of the polarizer unit 64, the light received by the light receiving element 66 The illuminance is maximum. Further, when the rotation angle θs of the polarizer unit 64 is an angle at which the transmission axis T2 is orthogonal to the transmission axis T1, the illuminance of light received by the light receiving element 66 is minimized.

  That is, the illuminance of light received by the light receiving element 66 periodically varies according to the rotation angle of the polarizer unit 64. Therefore, the polarization axis angle of the polarized light 67 can be measured by monitoring the illuminance of the light received by the light receiving element 66 while rotating the polarizer unit 64. Accordingly, the detection light of the light receiving unit when the polarizer unit 64 is rotated by installing the wire grid of the reference wire grid polarization element 63 in the 90 ° direction of the angle θ of the target wire grid (see FIG. 4). Can be set at a desired angle.

-Installation method of wire grid polarizer-
Next, the arrangement of the wire grid polarizer 32 of the wire grid polarizer 30 will be described.
Widely used wire grid polarizing elements are arranged in series on the same plane and installed in a frame. However, in this installation method, there is a case where a slight gap is generated between the wire grid polarizing elements, unpolarized light is emitted, and the alignment is not performed uniformly.

Therefore, in the present invention, a more preferable installation method that does not generate unpolarized light is used. An example of the installation method of a wire grid polarizing element is demonstrated referring FIG. FIG. 6 shows a top view of the wire grid polarizing element in the upper part and a cross section AA ′ in the lower part for easy understanding of the arrangement state of the wire grid polarizing element.
As shown in FIG. 6, an example of the wire grid polarizer 30 includes a rectangular frame 31 and a wire grid polarizing element 32 held by the frame 31. The wire grid polarizing element 32 is formed on a rectangular substrate 33 at an angle θ where the wire grid 34 is not perpendicular or parallel to the X direction. The plurality of wire grid polarization elements 32 are arranged in the X direction (longitudinal direction of the rod-shaped light source) with the end portions 36 of the wire grid polarization elements 32 overlapped with the back surface 35 of the substrate 33 being aligned.

  In an example installation method, the wire grid polarization elements 32 are partially overlapped and installed so that unpolarized light is not emitted. In that case, since the deflection | deviation performance of the wire grid polarizer 30 will deteriorate if the surface by which the wire grid 34 was processed is made to contact, the board | substrate back surface 35 is match | combined.

Further, another example of the installation method of the wire grid polarizing element will be described with reference to FIG. FIG. 7 also shows a top view of the wire grid polarizing element in the upper part and a cross section AA ′ in the lower part for easy understanding of the arrangement state of the wire grid polarizing element.
The wire grid polarization element 32 itself is the same as that shown in FIG. As shown in FIG. 7, the wire grid polarizer 30 in another example is arranged in a frame 31 with all of the plurality of wire grid polarization elements 32 facing the top of the page. Then, the wire grid 34 of one wire grid polarization element 32 is separated so as not to come into contact with the back surface 35 of the substrate 33 of the adjacent wire grid polarization element 32, and the end portions 36 are overlapped with each other in the X direction (rod-like shape). In the longitudinal direction of the light source).

By arranging the wire grid polarization element 32 as shown in FIG. 6 and FIG. 7, there is no gap 37 between the wire grid polarization element 32 and the wire grid polarization element 32, so that unpolarized light is converted into the wire grid polarization. It is not emitted from the child 30.
Therefore, alignment failure does not occur, and the occurrence of an axial displacement distribution of the liquid crystal compound in the liquid crystal layer can be suppressed.

(Irradiation angle)
Next, the irradiation angle on the backup roll will be described with reference to FIG.

As shown in FIG. 8, in a plane perpendicular to the axial center O of the backup roll 40,
A line that passes through the axis O of the backup roll 40 and is perpendicular to the substrate surface 38 of the wire grid polarizer 30 is defined as a reference line L1.
The angle formed by the reference line L1 and the line L2 connecting the axial center O of the backup roll 40 and the upstream end M in the conveyance direction of the irradiation region A of the polarized ultraviolet light on the continuous film support 50 is defined as θ1.
When the angle formed by the reference line L1 and the line L3 connecting the axial center O of the backup roll 40 and the downstream end N in the transport direction of the irradiation region A of polarized ultraviolet light on the continuous film support 50 is θ2, It is preferable to satisfy the relationship of the formula.
| Θ1-θ2 | <10 °
More preferably, | θ1−θ2 | <7 °, and most preferably | θ1−θ2 | = 0 °.

  By setting the relationship between θ1 and θ2 as described above, it is possible to irradiate polarized ultraviolet light directly from the front of the irradiation phase of the backup roll 40, and to suppress the occurrence of an axial shift distribution of the liquid crystal compound.

  The backup roll has a temperature control function. By warming the entire backup roll, the alignment element can be easily aligned, and an axial distribution can be prevented from occurring in the liquid crystal compound.

  Next, configurations other than the above of the method for producing a retardation film of the present invention will be described in the order of steps.

(Step of forming the first coating film)
An alignment layer forming material for forming an alignment layer having an alignment regulating force for the liquid crystal compound is applied and dried on the transported continuous film support.

(Support)
As the support, it is preferable to use a polymer film that can be wound around a backup roll. Examples of polymer film materials used as the support include cellulose acylate films (for example, cellulose triacetate film (refractive index 1.48), cellulose diacetate film, cellulose acetate butyrate film, cellulose acetate propionate film). Polyolefin such as polyethylene and polypropylene, polyester resin film such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone film, polyacrylic resin film such as polymethylmethacrylate, polyurethane resin film, polycarbonate film, polysulfone film, polyether Film, polymethylpentene film, polyetherketone film, (meth) acrylonitrile film Polyolefin, polymer having an alicyclic structure (norbornene resin (trade name “Arton (registered trademark)”, manufactured by JSR Corporation, amorphous polyolefin (trade name “ZEONEX (registered trademark)”, manufactured by ZEON CORPORATION)), Of these, triacetyl cellulose, polyethylene terephthalate (PET), and polymers having an alicyclic structure are preferable, and triacetyl cellulose is particularly preferable.

The film thickness of the support may be about 5 μm to 1000 μm, preferably 10 μm to 250 μm, more preferably 15 μm to 90 μm.
The

-Material for alignment layer formation-
Examples of the photo-alignment material used for the alignment film include, for example, JP-A-2006-285197, JP-A-2007-76839, JP-A-2007-138138, JP-A-2007-94071, and JP-A-2007-121721. Azo compounds described in JP-A No. 2007-140465, JP-A No. 2007-156439, JP-A No. 2007-133184, JP-A No. 2009-109831, Japanese Patent No. 3888848, and Japanese Patent No. 4151746, Aromatic ester compounds described in JP-A No. 2002-229039, maleimide and / or alkenyl-substituted nadiimide compounds having a photo-alignment unit described in JP-A Nos. 2002-265541 and 2002-31713, Patent No. 4205195, Japanese Patent No. 4251 Photocrosslinkable silane derivatives described in No. 8, photocrosslinkable polyimides, polyamides or esters described in JP-T-2003-520878, JP-A-2004-529220, and JP-A-4162850, JP-A-9-118717 JP-A-10-506420, JP-A-2003-505561, WO2010 / 150748, JP-A-2013-177561, JP-A-2014-12823, particularly cinnamate Examples thereof include compounds, chalcone compounds, and coumarin compounds. Particularly preferred examples include azo compounds, photocrosslinkable polyimides, polyamides, esters, cinnamate compounds, and chalcone compounds.

-Application method-
The methods for applying the liquid crystal layer forming material to the alignment film surface include curtain coating, dip coating, spin coating, print coating, spray coating, slot coating, roll coating, slide coating, and blade. Well-known methods, such as a coating method, a gravure coating method, a wire bar method, are mentioned.

-Drying process-
The drying is preferably performed at 50 ° C. to 130 ° C. for about 10 seconds to 10 minutes with an oven, warm air, an IR (infrared) infrared heater or the like.

(Step of forming alignment layer)
In this step, the first coating layer is irradiated with polarized ultraviolet light to impart an alignment regulating force to form an alignment layer. The step of imparting alignment regulating force is an operation for causing a photoreaction in the alignment layer forming material. The peak wavelength of polarized ultraviolet light is preferably 200 nm to 400 nm.

  The light source used for light irradiation is a commonly used light source such as a tungsten lamp, a halogen lamp, a xenon lamp, a xenon flash lamp, a mercury lamp, a mercury xenon lamp, a carbon arc lamp, or various lasers (eg, semiconductor laser, helium). Neon laser, argon ion laser, helium cadmium laser, YAG (Yttrium Aluminum Garnet) laser), light emitting diode, cathode ray tube, and the like can be given.

  In the photo-alignment, the photo-alignment material is oriented by non-contact light irradiation as described above, and therefore, non-uniform physical uneven shapes such as rubbing are not easily generated. Therefore, in a liquid crystal display device using an optical film manufactured using an alignment layer to which an alignment regulating force is imparted by optical alignment, light leakage is reduced and high contrast can be realized.

(Step of forming the second coating film)
A liquid crystal layer forming material containing a liquid crystal compound is applied and dried on the alignment layer to form a second coating film. The liquid crystal layer forming material can be applied and dried by the same method as the application and drying of the alignment layer forming material, and detailed description thereof will be omitted.

-Material for liquid crystal layer formation-
The liquid crystal layer-forming material contains a rod-like liquid crystal compound or a disk-like liquid crystal compound and at least a chiral agent, and may further contain other components such as an alignment controller, a polymerization initiator, and an alignment aid.

-Rod-shaped liquid crystal compound-
Examples of the rod-like liquid crystal compound include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used. In addition to the above low-molecular liquid crystalline molecules, high-molecular liquid crystalline molecules can also be used.

  It is more preferable to fix the orientation of the rod-like liquid crystal compound by polymerization, and examples of the polymerizable rod-like liquid crystal compound include those described in Makromol. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), US Pat. Nos. 4,683,327, 5,622,648 and 5,770,107, WO 95/22586, 95/24455. Publication No. 97/00600, No. 98/23580, No. 98/52905, JP-A-1-272551, No. 6-16616, No. 7-110469, No. 11-80081 The compounds described in the gazette and Japanese Patent Application No. 2001-64627 can be used. Further, as the rod-like liquid crystal compound, for example, those described in JP-T-11-513019 and JP-A-2007-279688 can be preferably used.

-Discotic liquid crystal compound-
As the discotic liquid crystal compound, for example, those described in JP2007-108732A and JP2010-244038A can be preferably used.

(Step of forming the liquid crystal layer)
The liquid crystal compound in the second coating film is aligned and the alignment is fixed to form a liquid crystal layer.

-Orientation of liquid crystal compounds-
Before the liquid crystal layer forming material is cured, an alignment treatment of the liquid crystal compound of the second coating film is performed. The alignment treatment can be performed by drying at room temperature or by heating. In the case of a thermotropic liquid crystal compound, the liquid crystal layer formed by the alignment treatment can generally be transferred by a change in temperature or pressure. In the case of a liquid crystal compound having lyotropic properties, it can be transferred also by a composition ratio such as the amount of solvent.

  When the rod-like liquid crystal compound develops a smectic phase, the temperature region in which the nematic phase develops is usually higher than the temperature region in which the rod-like liquid crystal compound develops a smectic phase. Therefore, the rod-like liquid crystal compound is heated to a temperature range where the rod-like liquid crystal compound develops a nematic phase, and then the heating temperature is lowered to a temperature region where the rod-like liquid crystal compound develops a smectic phase, thereby bringing the rod-like liquid crystal compound into a nematic phase. To a smectic phase. By using such a method as a smectic phase, a liquid crystal layer in which liquid crystal compounds are aligned with a high degree of order can be provided.

In the temperature range where the rod-like liquid crystal compound develops a nematic phase, it is necessary to heat for a certain time until the rod-like liquid crystal compound forms a monodomain. The heating time is preferably 10 seconds to 5 minutes, more preferably 10 seconds to 3 minutes, and most preferably 10 seconds to 2 minutes.
In the temperature range where the rod-like liquid crystal compound develops a smectic phase, it is necessary to heat for a certain time until the rod-like liquid crystal compound develops a smectic phase. The heating time is preferably 10 seconds to 5 minutes, more preferably 10 seconds to 3 minutes, and most preferably 10 seconds to 2 minutes.

-Fixed orientation-
The liquid crystal compound in the second coating film is aligned and the alignment is fixed to form a liquid crystal layer.
The orientation can be fixed by thermal polymerization or polymerization by active energy rays, and can be performed by appropriately selecting a polymerizable group or a polymerization initiator suitable for the polymerization. In consideration of production suitability and the like, a polymerization reaction by ultraviolet irradiation can be preferably used. When the irradiation amount of ultraviolet rays is small, unpolymerized polymerizable rod-like liquid crystal remains, which causes a change in temperature of optical characteristics and deterioration with time.
Therefore, it is preferable to determine the irradiation conditions such that the ratio of the remaining polymerizable rod-like liquid crystal is 5% or less, and the irradiation conditions depend on the prescription of the polymerizable composition and the thickness of the second coating film. UV irradiation dose as is preferably 50~1000mJ / cm ^2, and more preferably 100 to 500 mJ / cm ^2.
In addition, for details of the manufacturing method of the liquid crystal layer, the descriptions in Japanese Patent Application Laid-Open Nos. 2008-225281 and 2008-026730 can be referred to.

  The present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

[Example 1]
Below, each layer which comprises the retardation film of Example 1 is demonstrated. The alignment treatment was performed by the method shown in FIG.

(Formation of first coating film, formation of alignment layer)
The support surface of the cellulose triacetate film TD80UL (manufactured by Fujifilm) was subjected to alkali saponification treatment. Specifically, after immersing the support in an aqueous 1.5N sodium hydroxide solution at 55 ° C for 2 minutes, the substrate was washed in a water bath at room temperature and neutralized using 0.1N sulfuric acid at 30 ° C. did. After neutralization, it was washed in a water bath at room temperature and further dried with hot air at 100 ° C.
On the support, an alignment layer forming material having the following composition was applied with a wire bar. The film was dried with warm air at 60 ° C. for 60 seconds and further with warm air at 100 ° C. for 120 seconds to form a photo-alignment layer.

-Preparation of alignment layer forming material-
Photo-alignment material P-1 1.0 part by mass Butoxyethanol 33 parts by mass Propylene glycol monomethyl ether 33 parts by mass Water 33 parts by mass

The support on which the prepared alignment layer is formed is wound around a backup roll (diameter 1000 mm, made of stainless steel) (see FIG. 2), and an ultraviolet ray is used in the air using an air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.). Was irradiated. At this time, exposure was carried out by setting the transmission axis of a wire grid polarizer (manufactured by Moxtek, ProFlux PPL02) and the absorption axis of the alignment layer to be 60 degrees, and performing photo-alignment treatment. At this time, the illuminance of the ultraviolet rays used was 100 mW / cm ^{2 in} the UV (ultra-violet) -A region (integration of wavelengths 380 nm to 320 nm), and the irradiation amount was 1000 mJ / cm ² in the UV-A region.

(Formation of second coating film, formation of liquid crystal)
Subsequently, the following liquid crystal layer forming material was prepared.

-Preparation of coating liquid for liquid crystal layer formation-
Inverse wavelength dispersion liquid crystalline compound R-3 100 parts by mass Photopolymerization initiator 3.0 parts by mass (Irgacure 819, manufactured by BASF Corporation)
Fluorine-containing compound A 0.8 parts by mass Crosslinkable polymer O-2 0.3 parts by mass Chloroform 588 parts by mass

A liquid crystal layer forming material was applied on the alignment layer using a bar coater. After aging for 60 seconds at a film surface temperature of 100 ° C. and cooling to 70 ° C., the sample was irradiated with 1000 mJ / cm ² of ultraviolet rays using an air-cooled metal halide lamp (produced by Eye Graphics Co., Ltd.) under air. Positive A plate A-0 was formed by fixing the orientation state. In the formed liquid crystal layer, the slow axis direction was perpendicular to the polarized light irradiation direction (that is, perpendicular to the absorption axis of the polarizing plate) (the reverse wavelength dispersion liquid crystalline compound was aligned perpendicular to the polarized light irradiation direction. ) Using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments Co., Ltd.), the light incident angle dependence of retardation Re and the tilt angle of the optical axis were measured. Re was 130 nm at a wavelength of 550 nm, and retardation. Rth is 65 nm, Re (450) / Re (550) is 0.83, Re (650) / Re (550) is 1.05, the tilt angle of the optical axis is 0 °, and the reverse wavelength dispersion liquid crystalline compound is homogeneous. Orientation.

(Louvre and irradiation angle)
The louver pitch L was 10 mm, and the relationship L × (sin θ + 1) between the angle of the wire grid and L was 15.
In addition, as shown in FIG. 8, the polarized light was irradiated from the position where θ1 and θ2 were θ1 / θ2 = 10 ° / 10 °. In other words, the backup roll was irradiated from the front.

[Example 2]
A retardation film was produced in the same manner as in Example 1 except that the louver pitch L was 27 mm and L × (sin θ + 1) was 41.

[Example 3]
A retardation film was produced in the same manner as in Example 1 except that θ1 / θ2 = 5 ° / 11 °.

[Comparative Example 1]
A retardation film was produced in the same manner as in Example 1 except that the louver was not provided.

[Evaluation of axial misalignment distribution in the width direction]
About the retardation film produced by the said Example and comparative example, the axial shift distribution of the width direction (X direction of FIG. 2) was evaluated based on the following method and evaluation criteria.

The obtained retardation film (500 mm) was cut out by 1 m, and 10 pieces of small piece samples were cut out at equal intervals in the width direction. Using Axoscan (manufactured by Axometrics), 10 points were measured for all of the cut out small piece samples, and the axial angle of each small piece sample was obtained. Subsequently, the axial displacement distribution of the obtained retardation film was calculated using the following formula 1.
Axial deviation distribution = Maximum axis angle-Minimum axis angle (Equation 1)

The axial deviation distribution obtained above was judged based on the following evaluation criteria.
(Evaluation criteria)
A: Axial deviation distribution <0.5 °
B: 0.5 ° ≦ axial deviation distribution <1.0 °
C: 1.0 ° ≦ axis deviation distribution

  Table 1 shows the production conditions and evaluation results of Examples and Comparative Examples.

As shown in Table 1, the retardation film produced by the method for producing a retardation film of the present invention has an axial displacement distribution of 0.7 or less in the width direction, and the axis compared to the comparative example in which no louver is provided. The deviation distribution could be suppressed.
In particular, Example 1 in which L × (sin θ + 1) is less than 40 was able to further suppress the axial deviation distribution compared to Example 2 in which L × (sin θ + 1) was 40 or more.
Further, Examples 1 and 2 (θ1 / θ2 = 10 ° / 10 °) irradiated from the front side to the backup roll are compared with Example 3 (θ1 / θ2 = 5 ° / 11 °) shifted from the front side. The axial deviation distribution could be further suppressed.

DESCRIPTION OF SYMBOLS 10 Rod light source 11 Reflector 20 Louver 21 Parallel plate 30 Wire grid polarizer 31 Frame 32 Wire grid polarization element 33 Substrate 34 Wire grid 35 Back surface 36 End 37 Between wire grid polarization element and wire grid polarization element 38 Substrate surface 40 Backup Roll 50 Support on which first coating film is formed 60 Light orientation mechanism 61 Light source 62 Light 63 Reference wire grid polarizing element 64 Polarizer unit 65 Polarized light receiving unit 66 Light receiving element 67 Polarized light X Longitudinal direction of backup roll Y Transport direction T1 , T2 Transmission axis S Normal direction P0 Detection position θs Rotation angle L1 Reference line A Irradiation area M Upstream end of irradiation area N Downstream end of irradiation area O Axis center of backup roll L2 Axis center and upstream end of irradiation area Connected line L3 Axis center and irradiation area Line connecting downstream end θ1, θ2 angle

Claims (4)

A step of forming a first coating film by applying and drying an alignment layer forming material for forming an alignment layer having an alignment regulating force for a liquid crystal compound on a continuous film support to be conveyed;
Applying the alignment regulation force by irradiating polarized ultraviolet light to the first coating film to form the alignment layer; and applying a liquid crystal layer forming material containing the liquid crystal compound on the alignment layer; Drying to form a second coating film;
Aligning the liquid crystal compound in the second coating film, fixing the alignment and forming a liquid crystal layer;
A method for producing a retardation film comprising:
The step of forming the alignment layer is to irradiate the polarized ultraviolet light by winding the continuous film support on which the first coating film is formed around a backup roll capable of adjusting the temperature,
The polarized ultraviolet light is obtained by polarizing light emitted from a rod-shaped light source with a wire grid polarizer,
The wire grid of the wire grid polarizer is arranged at an angle θ that is not perpendicular or parallel to the longitudinal direction of the backup roll, and the light emitted from the rod light source is placed between the rod light source and the wire grid polarizer. The manufacturing method of the phase difference film which installs the louver which guides to the said wire grid polarizer.   The method for producing a retardation film according to claim 1, wherein the backup roll has a diameter of 2000 mm or less. 3. The method for producing a retardation film according to claim 1, wherein the angle θ of the wire grid and the pitch L (mm) of the louvers satisfy the relationship of the following formula.
L × (sin θ + 1) <40, where 0 <θ <90 ° In a plane perpendicular to the axis of the backup roll,
A line that passes through the axis of the backup roll and is perpendicular to the substrate surface of the wire grid polarizer is a reference line.
An angle formed by the reference line and a line connecting the axial center of the backup roll and the upstream end in the transport direction of the polarized ultraviolet light irradiation region on the continuous film support is θ1,
When the angle formed by the reference line and the line connecting the axial center of the backup roll and the downstream end in the transport direction of the polarized ultraviolet light irradiation region on the continuous film support is θ2, The manufacturing method of the retardation film of Claim 1 or 2 which satisfy | fills a relationship.
| Θ1-θ2 | <5 °