JP6318481B2 - Method for producing optical film transfer body, method for producing optical film - Google Patents

Description

  The present invention relates to an optical film having a retardation layer made of a polymerizable liquid crystal monomer, for example, an optical film formed by laminating a linearly polarizing plate and a quarter-wave plate, and the quarter-wave plate is changed to a half-wavelength. The present invention relates to an optical film configured by laminating a retardation layer and a quarter-wave retardation layer.

  Conventionally, regarding an image display device, use of an optical film that secures various optical characteristics by imparting a desired retardation to transmitted light by a retardation layer has been proposed. Such a retardation layer is formed by laminating a polymerizable liquid crystal monomer on an alignment film, then raising the temperature to the phase transition point, and then polymerizing the polymerizable liquid crystal monomer by ultraviolet irradiation or the like to fix the alignment state of the liquid crystal. It is produced by this. In addition, the alignment film can be created by transferring the fine uneven shape created in the shaping mold by, for example, a shaping process using the shaping mold, or by a so-called photo-alignment technique. can do.

  Specifically, a reflection reducing film using a circularly polarizing plate, which is such an optical film, includes a linear polarizing plate and a quarter-wave plate, and is disposed on the panel surface (viewer side surface) of the image display panel. . This optical film converts extraneous light directed to the panel surface of the image display panel into linearly polarized light by a linear polarizing plate, and then converts it into circularly polarized light by a quarter wavelength plate. Here, the extraneous light by the circularly polarized light is reflected by the surface of the image display panel or the like, but the rotation direction of the polarization plane is reversed during the reflection. As a result, contrary to the arrival time, this reflected light is converted into linearly polarized light in the direction shielded by the linear polarizing plate by the quarter wavelength plate, and then shielded by the subsequent linear polarizing plate. Outgoing emission is significantly suppressed. In this reflection reducing film, the quarter retardation plate can be constituted by a retardation layer made of a polymerizable liquid crystal monomer.

  With regard to this optical film, Patent Document 1 and the like include a 1/2 wavelength phase difference layer that imparts a phase difference of ½ wavelength to transmitted light, and a 1 / wavelength that imparts a phase difference of ¼ wavelength to transmitted light. A method has been proposed in which a quarter-wave plate is formed by laminating four-wavelength retardation layers to use a liquid crystal material having a positive dispersion characteristic so that the quarter-wave plate functions with a reverse dispersion characteristic. Here, the reverse dispersion characteristic is a wavelength dispersion characteristic in which the phase difference in transmitted light is smaller as the wavelength is shorter.

  In addition, a pattern retardation film which is an optical film of this type is applied to an image display device by a passive method and used for three-dimensional image display. In this passive type image display device, pixels of a continuous liquid crystal display panel are sequentially assigned to the right eye and the left eye alternately, and driven by the right eye image data and the left eye image data, respectively. Display the left-eye image at the same time. The pattern retardation film is disposed on the panel surface (viewer side surface) of the liquid crystal display panel, and imparts a phase difference to the outgoing light by the linearly polarized light from the right-eye pixel and the left-eye pixel by the retardation layer, Convert to circular polarized light with different directions for right eye and left eye. As a result, in the passive method, glasses equipped with corresponding polarizing filters are worn, and a right-eye image and a left-eye image are selectively provided to the viewer's right and left eyes, respectively, and a three-dimensional image is displayed. can do. In the pattern retardation film, the retardation layer can be constituted by a retardation layer made of a polymerizable liquid crystal monomer.

  By the way, in the optical film provided with the retardation layer of this kind of polymerizable liquid crystal monomer, there is a problem that the retardation value of the retardation layer is lowered due to preservation in a normal temperature and humidity environment. Hereinafter, such a decrease in retardation value is referred to as retardation drop.

JP-A-10-68816 JP 2000-284126 A

  This invention is made | formed in view of such a condition, It enables it to reduce a retardation drop regarding the optical film provided with the phase difference layer by a polymeric liquid crystal monomer.

  The present inventor has conducted extensive research to solve the above problems, and by polymerizing the polymerizable liquid crystal monomer related to the retardation layer in a state where the order parameter (also referred to as orientation parameter or orientation order degree) is reduced, The idea of reducing the retardation drop by suppressing the decrease of the order parameter after polymerization was led to the completion of the present invention. The order parameter can be measured by the measuring method described in Japanese Patent Application Laid-Open No. 2007-256438.

(1) A method for producing a transfer body for an optical film comprising a support substrate and a transfer layer,
An alignment film production step of producing an alignment film on the substrate according to the support substrate;
A step of producing a retardation layer for producing a retardation layer of a polymerizable liquid crystal that imparts a desired retardation to transmitted light by laminating and curing a polymerizable liquid crystal monomer on the alignment film;
The transfer layer is at least a retardation layer of a polymerizable liquid crystal,
The step of producing the retardation layer includes
A retardation layer of the polymerizable liquid crystal having an order parameter of 0.35 to 0.55 is prepared.

  According to (1), by polymerizing the polymerizable liquid crystal monomer related to the retardation layer in a state where the order parameter is lowered, it is possible to suppress the drop in the order parameter after polymerization and reduce the retardation drop.

(2) In (1),
The step of producing the retardation layer includes
A coating process for coating the polymerizable liquid crystal monomer coating liquid on the alignment film;
A drying step of drying the coating liquid coated on the alignment film;
An ultraviolet irradiation step of producing a retardation layer of the polymerizable liquid crystal by polymerizing the polymerizable liquid crystal monomer provided on the alignment film by irradiation of ultraviolet rays,
In the ultraviolet irradiation step, ultraviolet rays are irradiated in an oxygen-containing atmosphere to polymerize the polymerizable liquid crystal monomer.

  According to (2), the retardation drop can be reduced by polymerizing the polymerizable liquid crystal monomer related to the retardation layer in a state where the order parameter is lowered by a more specific configuration.

(3) In (1),
The step of producing the retardation layer includes
A coating process for coating the polymerizable liquid crystal monomer coating liquid on the alignment film;
A drying step of drying the coating liquid applied on the alignment film;
An ultraviolet irradiation step of producing a retardation layer of the polymerizable liquid crystal by polymerizing the polymerizable liquid crystal monomer provided on the alignment film by irradiation of ultraviolet rays,
In the ultraviolet irradiation step, the polymerizable liquid crystal monomer is polymerized by irradiating ultraviolet rays at a temperature of 50 ° C. or higher and a glass transition temperature (Tg) of the support substrate or lower.

  According to (3), the retardation drop can be reduced by polymerizing the polymerizable liquid crystal monomer related to the retardation layer in a state where the order parameter is lowered by a more specific configuration.

(4) An alignment film creating step for a 1/2 wavelength retardation layer that creates an alignment film for a 1/2 wavelength retardation layer according to a 1/2 wavelength retardation layer on a first substrate;
A 1/2 wavelength retardation layer is formed that gives a retardation of 1/2 wavelength to transmitted light by laminating a polymerizable liquid crystal monomer on the alignment film for the 1/2 wavelength retardation layer and curing it. A half-wave retardation layer forming step,
An alignment film creating step for a quarter wavelength retardation layer for creating an alignment film for a quarter wavelength retardation layer according to a quarter wavelength retardation layer on a second substrate;
A quarter-wave retardation layer is formed that imparts a retardation corresponding to a quarter wavelength to transmitted light by laminating a polymerizable liquid crystal monomer on the alignment film for the quarter-wave retardation layer to be cured. A quarter wavelength retardation layer creating step;
A bonding step of bonding the half-wave retardation layer and the quarter-wave retardation layer with an adhesive layer;
The 1/4 wavelength retardation layer creation step and the 1/2 wavelength retardation layer creation step are:
The quarter wavelength retardation layer and the half wavelength retardation layer having an order parameter of 0.35 or more and 0.55 or less are prepared.

  According to (4), when producing a quarter-wave plate by laminating a half-wave retardation layer and a quarter-wave retardation layer with an adhesive layer to produce a circularly polarizing plate, the order parameter By polymerizing the polymerizable liquid crystal monomer related to the retardation layer in a state in which the retardation is lowered, it is possible to suppress a drop in order parameters after polymerization and reduce retardation drop.

(5) In (4),
The 1/4 wavelength retardation layer creation step and the 1/2 wavelength retardation layer creation step are:
A coating step of coating the polymerizable liquid crystal monomer coating liquid on the alignment film for the ½ wavelength retardation layer and the alignment film for the ¼ wavelength retardation layer;
A drying step of drying the coating liquid coated on the alignment film for the ½ wavelength retardation layer and the alignment film for the ¼ wavelength retardation layer;
The 1/4 wavelength retardation is obtained by polymerizing the polymerizable liquid crystal monomer provided on the alignment film for the ½ wavelength retardation layer and the alignment film for the ¼ wavelength retardation layer by ultraviolet irradiation. And an ultraviolet irradiation step for producing the ½ wavelength retardation layer,
In the ultraviolet irradiation step, ultraviolet rays are irradiated in an oxygen-containing atmosphere to polymerize the polymerizable liquid crystal monomer.

  According to (5), the retardation drop can be reduced by polymerizing the polymerizable liquid crystal monomer related to the retardation layer in a state where the order parameter is lowered by a more specific configuration.

(6) In (4),
The 1/4 wavelength retardation layer creation step and the 1/2 wavelength retardation layer creation step are:
A coating step of coating the polymerizable liquid crystal monomer coating liquid on the alignment film for the ½ wavelength retardation layer and the alignment film for the ¼ wavelength retardation layer;
A drying step of drying the coating liquid coated on the alignment film for the ½ wavelength retardation layer and the alignment film for the ¼ wavelength retardation layer;
The 1/4 wavelength retardation is obtained by polymerizing the polymerizable liquid crystal monomer provided on the alignment film for the ½ wavelength retardation layer and the alignment film for the ¼ wavelength retardation layer by ultraviolet irradiation. And an ultraviolet irradiation step for producing the ½ wavelength retardation layer,
In the ultraviolet irradiation step, the polymerizable liquid crystal monomer is polymerized by irradiating ultraviolet rays at a temperature of 50 ° C. or higher and a glass transition temperature (Tg) of the support substrate or lower.

  According to (6), the retardation drop can be reduced by polymerizing the polymerizable liquid crystal monomer related to the retardation layer in a state where the order parameter is lowered by a more specific configuration.

(7) an alignment film production step of producing an alignment film on a substrate made of a transparent film;
A step of producing a retardation layer for producing a retardation layer of a polymerizable liquid crystal that imparts a desired retardation to transmitted light by laminating and curing a polymerizable liquid crystal monomer on the alignment film;
The step of producing the retardation layer includes
A retardation layer of the polymerizable liquid crystal having an order parameter of 0.35 to 0.55 is prepared.

  According to (7), it can apply to an optical film and can reduce a retardation drop.

(8) In (7),
The step of producing the retardation layer includes
A coating process for coating the polymerizable liquid crystal monomer coating liquid on the alignment film;
A drying step of drying the coating liquid coated on the alignment film;
An ultraviolet irradiation step of producing a retardation layer of the polymerizable liquid crystal by polymerizing the polymerizable liquid crystal monomer provided on the alignment film by irradiation of ultraviolet rays,
In the ultraviolet irradiation step, ultraviolet rays are irradiated in an oxygen-containing atmosphere to polymerize the polymerizable liquid crystal monomer.

  According to (8), the retardation drop can be reduced by polymerizing the polymerizable liquid crystal monomer related to the retardation layer in a state where the order parameter is lowered by a more specific configuration.

(9) In (7),
The step of producing the retardation layer includes
A coating process for coating the polymerizable liquid crystal monomer coating liquid on the alignment film;
A drying step of drying the coating liquid applied on the alignment film;
An ultraviolet irradiation step of producing a retardation layer of the polymerizable liquid crystal by polymerizing the polymerizable liquid crystal monomer provided on the alignment film by irradiation of ultraviolet rays,
In the ultraviolet irradiation step, the polymerizable liquid crystal monomer is polymerized by irradiating ultraviolet rays at a temperature of 50 ° C. or higher and a glass transition temperature (Tg) of the support substrate or lower.

  According to (9), the retardation drop can be reduced by polymerizing the polymerizable liquid crystal monomer related to the retardation layer in a state where the order parameter is lowered by a more specific configuration.

(10) A transfer body for an optical film comprising a support substrate and a transfer layer,
The transfer layer is
A retardation layer of a polymerizable liquid crystal by polymerization of a polymerizable liquid crystal monomer laminated on an alignment film is provided.
The retardation layer of the polymerizable liquid crystal has an order parameter of 0.35 to 0.55.

  According to (10), when the polymerizable liquid crystal monomer related to the retardation layer is polymerized in a state where the order parameter is lowered, the drop in the order parameter after polymerization can be suppressed and the retardation drop can be reduced.

(11) In (10),
The transfer layer is
At least a quarter-wave retardation layer that imparts a phase difference of ¼ wavelength to transmitted light, an adhesive layer, and a ½-wave retardation layer that imparts a phase difference of ½ wavelength to transmitted light And
By the adhesive layer, the ½ wavelength retardation layer and the ¼ wavelength retardation layer are bonded together,
The retardation layer of the polymerizable liquid crystal is the quarter wavelength retardation layer and the half wavelength retardation layer.

  According to (11), retardation drops can be reduced when a circularly polarizing plate is produced by a transfer method.

(12) A substrate comprising a transparent film and a retardation layer of a polymerizable liquid crystal obtained by polymerization of a polymerizable liquid crystal monomer,
The retardation layer of the polymerizable liquid crystal has an order parameter of 0.35 to 0.55.

  According to (12), it can apply to an optical film and can reduce a retardation drop.

(13) In (12),
The retardation layer of the polymerizable liquid crystal is
It is the said transfer layer transcribe | transferred from the optical film transfer body of Claim 1 or Claim 2.

  According to (13), the retardation drop can be reduced with respect to the optical film produced by the transfer method.

(14) a substrate made of a transparent film;
An optical functional layer of a linearly polarizing plate that functions as a linearly polarizing plate;
A quarter wave plate is laminated,
The quarter-wave plate is
A quarter-wave retardation layer that provides at least a quarter-wave phase difference to transmitted light, an adhesive layer, and a half-wave retardation layer that imparts a half-wave phase difference to transmitted light; With
By the adhesive layer, the ½ wavelength retardation layer and the ¼ wavelength retardation layer are bonded together,
The 1/2 wavelength retardation layer and the 1/4 wavelength retardation layer are:
It is a retardation layer by polymerization of a polymerizable liquid crystal monomer laminated on an alignment film,
The order parameter is 0.35 or more and 0.55 or less.

  According to (14), the retardation drop can be reduced with respect to the circularly polarizing plate.

  (15) The optical film of (12), (13), or (14) is disposed on the panel surface of the image display panel.

  According to (15), the image display apparatus provided with the optical film formed by reducing the retardation drop of the retardation layer by a polymerizable liquid crystal monomer can be provided.

  This invention can reduce retardation drop regarding the optical film provided with the phase difference layer by a polymerizable liquid crystal monomer.

It is sectional drawing which shows the image display apparatus which concerns on 1st Embodiment of this invention. It is a figure where it uses for description of the optical film applied to the image display apparatus of FIG. It is sectional drawing which shows the transfer film which concerns on the optical film of FIG. It is a figure where it uses for description of the manufacturing process of the transfer film of FIG. It is a figure where it uses for description of the manufacturing process of the optical film by the transfer film of FIG. It is a figure where it uses for description of the process of the continuation of FIG. It is a figure where it uses for description of the manufacturing process of FIG. It is a figure with which it uses for description of the continuation of FIG. It is a chart which shows a verification result.

[First Embodiment]
[Optical film and image display device]
FIG. 1 is a diagram showing an image display apparatus according to the first embodiment of the present invention. In the image display device 11, an optical film 13 is disposed on the panel surface (viewer side surface) of the image display panel 12. Here, the image display panel 12 is an organic EL panel, for example, and displays a desired color image. Note that the image display panel 12 is not limited to the organic EL panel, and various image display panels such as a liquid crystal display panel can be widely applied.

  The optical film 13 is an optical film that suppresses reflection of extraneous light arriving at the image display panel 12 by the function of a circularly polarizing plate. For this reason, the optical film 13 is configured by laminating a linear polarizing plate 15 and a quarter-wave plate 16. The optical film 13 is peeled off a separator film (not shown) to expose the pressure-sensitive adhesive 14 with a pressure-sensitive adhesive, and is then attached and held on the panel surface of the image display panel 12 by the pressure-sensitive adhesive layer 14. Instead of the pressure-sensitive adhesive, the optical film 13 may be arranged by various adhesives such as an ultraviolet curable resin and an adhesive. The linear polarizing plate 15 and the quarter wavelength plate 16 are integrated with each other through the adhesive layer 17. Here, although various adhesives such as an ultraviolet curable resin, a thermosetting resin, and a pressure sensitive adhesive can be widely applied, the adhesive layer 17 is made of an ultraviolet curable resin from the viewpoint of reducing the overall thickness. In this case, it can be formed with a thickness of about 1 μm.

  The quarter wavelength plate 16 includes a quarter wavelength retardation layer 18 that imparts a phase difference of ¼ wavelength to transmitted light, and a ½ wavelength that imparts a phase difference of ½ wavelength to the transmitted light. It is comprised by the laminated body which bonded together the phase difference layer 19 with the contact bonding layer 20. FIG. Thereby, the optical film 13 sufficiently suppresses reflection of extraneous light in a wide wavelength band used for displaying a color image.

  The quarter-wave plate 16 is used for the production of the quarter-wave retardation layer 18 and the half-wave retardation layer 19. An alignment film 23 is provided on each of the image display panel 12 side and the linearly polarizing plate 15 side, whereby a transfer method is applied to produce an optical film 13 to reduce the overall thickness, and a 1/4 wavelength phase difference. The layer alignment film 22 and the ½ wavelength retardation layer alignment film 23 function as a protective layer to reduce damage to the ¼ wavelength retardation layer 18 and the ½ wavelength retardation layer 19.

  Accordingly, in the image display device 11, the ¼ wavelength phase difference layer 18, the ½ wavelength phase difference layer 19, and the linear polarizing plate 15 are sequentially arranged from the display screen side of the image display panel 12. In addition, as shown in FIG. 2, the slow axes (indicated by arrows respectively) of the ½ wavelength phase difference layer 19 and the ¼ wavelength phase difference layer 18 with respect to the transmission axis of the linearly polarizing plate 15 indicated by arrows. Are arranged so as to form angles of 15 degrees and 75 degrees counterclockwise, respectively.

  The quarter-wave retardation layer alignment film 22 and the half-wave retardation layer alignment film 23 are formed by forming a fine uneven shape on the surface, and 1 / The liquid crystal material according to the four-wavelength phase difference layer 18 and the half-wavelength phase difference layer 19 is aligned. The quarter-wave retardation layer alignment film 22 and the half-wave retardation layer alignment film 23 have a 10-point average roughness (Rz) of 10 nm to 45 nm, and an average surface roughness. (Ra) is 1 nm or more and 4 nm or less. As a result, the quarter-wave retardation layer alignment film 22 and the half-wave retardation layer alignment film 23 are disposed between the corresponding quarter-wave retardation layer 18 and the half-wave retardation layer 19. Sufficient adhesion strength can be secured, and variations in the quarter-wave retardation layer 18 and the half-wave retardation layer 19 related to so-called black luminance can be sufficiently reduced.

  In this embodiment, the quarter-wave retardation layer alignment film 22 and the half-wave retardation layer alignment film 23 are formed after the forming resin layer for forming a fine concavo-convex shape is formed. A fine concavo-convex shape is created and formed on the surface of this shaping resin layer by a shaping treatment. In this embodiment, an ultraviolet curable resin is applied to the shaping resin, and an acrylic ultraviolet curable resin is used. However, the present invention is not limited to this, and various resins used for the shaping process can be widely applied. it can.

  In addition, the fine uneven shape relating to the alignment film 23 for 1/2 wavelength retardation layer and the alignment film 22 for 1/4 wavelength retardation layer is formed by a line (line) uneven shape extending in one direction. The direction extending in one direction is formed so as to be at an angle of 15 degrees and 75 degrees counterclockwise with respect to the transmission axis of the linearly polarizing plate 15, respectively.

  The quarter-wave retardation layer 18 and the half-wave retardation layer 19 are made of a liquid crystal material that is solidified (cured) while maintaining refractive index anisotropy by the orientation regulating force of the corresponding orientation films 22 and 23. It is formed. More specifically, the quarter-wave retardation layer 18 and the half-wave retardation layer 19 are formed by laminating a polymerizable liquid crystal monomer on the alignment films 22 and 23, and then raising the temperature to the phase transition point. It is produced by polymerizing a polymerizable liquid crystal monomer by irradiation to fix the alignment state of the liquid crystal. Although the ¼ wavelength retardation layer 18 and the ½ wavelength retardation layer 19 can widely apply various liquid crystal materials applicable to this type of optical film, in this embodiment, the same material is used. Applied. More specifically, for example, the compounds represented by the following chemical formulas (1) to (13) are used for the quarter-wave retardation layer 18 and the half-wave retardation layer 19.

  Although various adhesives such as an ultraviolet curable resin, a thermosetting resin, and a pressure sensitive adhesive can be widely applied to the adhesive layer 20, an ultraviolet curable resin is applied from the viewpoint of reducing the overall thickness. In this case, it can be formed with a thickness of about 1 μm.

  The linearly polarizing plate 15 is provided with the optical functional layer 15B after the lower surface side of the base material 15A made of a transparent film such as TAC (triacetylcellulose) is saponified. In addition, 15 A of base materials replace with this, poly (meth) methyl acrylate, poly (meth) butyl acrylate, methyl (meth) acrylate- (meth) butyl acrylate copolymer, (meth) acrylate methyl- A resin such as an acrylic resin such as a styrene copolymer, a glass such as soda glass, potash glass, lead glass, or quartz glass can be used.

  The optical functional layer 15B is a part that bears an optical function as a linearly polarizing plate, and is produced, for example, by adsorbing and orienting iodine compound molecules on a film material made of polyvinyl alcohol (PVA).

  Thus, in the optical film 13, by configuring the quarter wavelength plate 16 with a laminate in which the quarter wavelength retardation layer 18 and the half wavelength retardation layer 19 are bonded by the adhesive layer 20, respectively. The ¼ wavelength phase difference layer 18 and the ½ wavelength phase difference layer 19 created by separate processes can be used, and thereby an alignment film and a phase difference layer are sequentially laminated. In this case, it can be created by effectively avoiding shortage of adhesion and insufficient adhesion, and as a result, it can be created with high stability and reliability.

  Further, the quarter-wave retardation layer alignment film 22 and the half-wave retardation layer alignment film 23 used for the production of the quarter-wave retardation layer 18 and the half-wave retardation layer 19 are respectively images. It is provided on the display panel 12 side and the linearly polarizing plate 15 side, whereby the transfer film is applied to produce the optical film 13 to reduce the overall thickness, and the quarter wavelength retardation layer alignment film 22, 1 / The alignment film 23 for the two-wavelength phase difference layer can function as a protective layer, and damage to the ¼ wavelength phase difference layer 18 and the ½ wavelength phase difference layer 19 can be reduced. The transfer method refers to, for example, when a desired layer is formed on a base material, the layer is not directly formed on the base material, but can be peeled once on a releasable support. After forming the transfer body by laminating the layers, the layer formed on the support is finally placed on the substrate (transfer base material) on which the layer is to be laminated according to the process, demand, etc. In this method, a desired layer is formed on the substrate by bonding and laminating, and then peeling and removing the support.

[Transcript]
In the optical film 13, the quarter-wave plate 16 and the linear polarizing plate 15 are integrated by the adhesive layer 17, and the transfer method is applied to a series of processes related to this integration. Thereby, in this embodiment, the substrate to be transferred is the linear polarizing plate 15, and the layers (transfer layers) used for transfer are the quarter-wave retardation layer alignment film 22 and the quarter-wave retardation layer 18. , An adhesive layer 20, a ½ wavelength phase difference layer 19, and a ½ wavelength phase difference layer alignment film 23.

  FIG. 3 is a diagram showing a configuration of a transfer film 21 which is this transfer body. The transfer film 21 is formed on the support base material 25, the quarter-wave retardation layer alignment film 22, the quarter-wave retardation layer 18, the adhesive layer 20, and the half-wave retardation layers 19, 1/2. A wavelength retardation layer alignment film 23 and a substrate 24 are provided.

  Here, the support base material 25 is a base material that is detachably supported after the transfer layer is detachably supported and the transfer layer is bonded and laminated on the transfer target substrate. In this embodiment, a PET (Polyethylene terephthalate) film, which is a transparent film material, is applied, whereby the transfer film 21 is configured to be able to inspect optical characteristics. The PET film is subjected to corona treatment as necessary, whereby the adhesion force is appropriately set. The support base material 25 may have a sheet shape as a whole. The support substrate 25 may be a resinous film material made of a resin such as a polyester resin such as polyethylene terephthalate, polybutylene terephthalate, or polyethylene aphthalate, or a polyolefin resin such as polypropylene or polymethylpentene.

  When the peelability from the transfer layer is insufficient, the support base material 25 is provided with a release layer that promotes peeling on the transfer layer side. Here, the release layer can be applied with a material having relatively high adhesion to the support substrate 25 (low peelability) and low adhesion to the transfer layer (high peelability). . In this embodiment, the lowermost layer of the transfer layer is an alignment film 22 for a quarter wavelength retardation layer made of an ultraviolet curable resin. Polymer compound), fluorine-based resin, melamine resin, epoxy resin, or a mixture of these resins and other resins (acrylic resin, cellulose-based resin, polyester resin, etc.) as appropriate.

  Incidentally, when the peelability by the release layer is insufficient, a release layer may be provided between the support substrate 25 and the release layer, and this release layer may be used to supplement the peelability by the release layer. . For the release layer, a material having relatively low adhesion to the support film (high peelability) and high adhesion to the release layer (low peelability) can be applied. More specifically, in this embodiment, the release layer includes an acrylic resin, a cellulose resin, a polyester resin, a urethane resin, a vinyl chloride-vinyl acetate copolymer, or a mixture of two or more selected from the above. Alternatively, a mixture of one or more selected from the above and other resins can be applied.

  The base material 24 is a base material that carries the transfer layer in a peelable manner and is used for peeling and removing as appropriate at the time of transfer or the like. In this embodiment, it is comprised similarly to the support body base material 25. FIG. Also in the base material 24, in order to appropriately set the adhesion between the lower-layer half-wave retardation layer alignment film 23, corona treatment is performed as necessary, and a release layer and a release layer are provided. Can be formed.

〔Manufacturing process〕
FIG. 4 is a diagram for explaining the manufacturing process of the transfer film 21. In this manufacturing process, the half-wave retardation layer alignment film 23 and the half-wave retardation layer 19 are formed on the substrate 24 (FIG. 4A). In addition, the quarter-wave retardation layer alignment film 22 and the quarter-wave retardation layer 18 are formed on the substrate 25 (FIG. 4B). In the manufacturing process, the optical characteristics of the ½ wavelength phase difference layer 19 and the ¼ wavelength phase difference layer 18 are inspected by transmitted light, respectively, and then the ½ wavelength phase difference layer 19 and ¼ wavelength are obtained by the adhesive layer 20. The phase difference layer 18 is bonded together, thereby creating the transfer film 21 (FIG. 4C). This optical characteristic includes the direction of the slow axis described above with reference to FIG. 2, the defect of the retardation layer, and the like.

  In the case where the ½ wavelength phase difference layer 19 and the ¼ wavelength phase difference layer 18 are individually formed and integrated as in this embodiment, the ½ wavelength phase difference layer 19, 1 / The optical characteristics of the four-wavelength retardation layer 18 can be inspected. As a result, the quality can be improved and the optical film 13 can be produced stably.

  FIG. 5 is a diagram for explaining the manufacturing process of the optical film 13 that follows. In this manufacturing process, only the base material 24 is peeled from the transfer film 21 (FIG. 5A), and then attached to the linear polarizing plate 15 via the adhesive layer 17 (FIG. 5B), thereby supporting the manufacturing process. The optical film 13 is formed integrally with the body substrate 25 and the quarter-wave retardation layer alignment film 22 and with the half-wave retardation layer alignment film 23 left behind. In addition, you may make it provide the transfer film 21 to the manufacturing process of the optical film 13 by providing the process which peels the base material 24 in the manufacturing process of the transfer film 21, and the form which peeled the base material 24.

  Thus, the alignment film 23 for a half-wave retardation layer protects the underlying half-wave retardation layer 19 until the substrate 24 is peeled off and bonded to the linearly polarizing plate 15.

  Subsequently, as shown in FIG. 6, in this step, after the support base material 25 is peeled from the optical film 13 (FIG. 6A), the adhesive layer 14 and the separator film are arranged to have a desired size. The optical film 13 is produced by cutting. In the subsequent manufacturing process of the image display device 11, in the final process, the separator film is peeled to expose the adhesive layer 14, and the optical film 13 is attached to the panel surface of the image display panel 12 through the adhesive layer 14 (FIG. 6). (B)). In addition, you may perform the process which peels the support body base material 25 in the manufacturing process of an image display apparatus.

  As a result, the quarter-wave retardation layer alignment film 22 protects the upper quarter-wave retardation layer 18 after the substrate 25 is peeled off until it is bonded to the image display panel 12.

  FIG. 7 is a diagram showing the manufacturing process described above with reference to FIGS. 4 (A) and 4 (B). In FIG. 7, the structure in which the quarter-wave retardation layer alignment film 22 and the quarter-wave retardation layer 18 are formed on the base material 25 according to FIG. And show.

  In this manufacturing process, the base material 24 is pulled out from the supply reel 31, coated with a coating solution of an ultraviolet curable resin with a die 32, and then dried with a drying furnace 33. Note that the coating of the coating liquid is not limited to using a die, and various methods can be applied. In this manufacturing process, the roll plate 34 is a mold for molding in which the fine irregularities related to the alignment film 23 for the ½ wavelength retardation layer are formed on the peripheral side surface. In this manufacturing process, the base material 24 coated with an ultraviolet curable resin is pressed against a roll plate 34 by a pressure roller 35, and the ultraviolet curable resin is cured by irradiation with ultraviolet rays by an ultraviolet irradiation device 36 made of high-pressure mercury vapor. . Thus, in the manufacturing process, the uneven shape formed on the peripheral side surface of the roll plate 34 is transferred to the substrate 24. Thereafter, the substrate 24 is peeled off together with the ultraviolet curable resin cured from the roll plate 34 by the peeling roller 37, and a coating liquid of a liquid crystal material is applied by the die 39. Then, after drying in the drying furnace 40, the liquid crystal material is cured by irradiating ultraviolet rays from the ultraviolet irradiating device 41, and taken up on the take-up reel 42. By this series of treatments, the half-wave retardation layer alignment film 23 and the half-wave retardation layer 19 are formed on the substrate 24.

  Further, in this manufacturing process, instead of the roll plate 34, a roll plate 44 used for the production of the alignment film 22 for the quarter wavelength retardation layer is arranged, and similarly, the base material 25 is pulled out from the supply reel 31, After coating the coating solution of the ultraviolet curable resin by 32, the coating liquid is dried by the drying furnace 33, and the quarter wavelength retardation layer alignment film 22 is formed by the roll plate 44. Further, after the liquid crystal material is applied and dried, the liquid crystal material is cured and wound on the take-up reel 52, whereby the quarter-wave retardation layer alignment film 22 is formed on the substrate 25. The quarter wavelength retardation layer 18 is formed.

  FIG. 8 is a diagram for explaining the bonding process of the quarter wavelength retardation layer 18 and the half wavelength retardation layer 19 (FIG. 4C). In this manufacturing process, the laminate of the base material 24, the ½ wavelength retardation layer alignment film 23, and the ½ wavelength retardation layer 19 is drawn out from the take-up reel 42, and the ultraviolet curing as an adhesive is performed by the die 55. After the application of the conductive resin, the laminate of the substrate 25, the quarter-wave retardation layer alignment film 22 and the quarter-wave retardation layer 18 which are dried by the drying furnace 56 and pulled out from the take-up reel 52, Laminate. Thereafter, the ultraviolet curable resin applied by irradiating the ultraviolet rays with the ultraviolet irradiation device 57 is cured, and then the substrate 24 is peeled off and taken up on the take-up reel 58.

[Countermeasures for retardation drop]
By the way, in the phase difference film wound up on the take-up reels 42 and 52 described above, the retardation value of the phase difference layers 18 and 19 is lowered by storage in a room temperature and humidity environment, and the retardation is obtained when the adhesive layer 20 is laminated. A drop has occurred. Thereby, in the optical film 13, there exists a possibility that it may become difficult to ensure a desired optical characteristic.

  Therefore, in this embodiment, the polymerizable liquid crystal monomer related to the retardation layer is polymerized in a state where the order parameter (orientation parameter) is lowered, thereby suppressing the drop in the order parameter after polymerization and reducing the retardation drop.

  According to the results of various studies here, in the quarter-wave retardation layer 18 and the half-wave retardation layer 19, if the order parameter is made from 0.35 to 0.55, If it is preferably produced by 0.35 or more and 0.45 or less, the retardation drop due to storage in a normal temperature and normal humidity environment can be sufficiently reduced in practice. If the order parameter is less than 0.35, the orientation is insufficient and the desired retardation cannot be obtained. If the order parameter exceeds 0.55 and approaches 1, the retardation drop becomes large, which is not preferable. The feature of the present invention is to suppress retardation drop by lowering the order parameter slightly from the normal orientation. In addition, lack of the absolute value of the retardation due to a slight decrease in orientation is not a problem because a desired retardation value can be obtained by appropriately increasing the thickness of the retardation layer accordingly.

  The order parameter S is used as an index representing the degree of orientation of the polymer film and the degree of orientation of the liquid crystal, and is defined in the range of 0 ≦ S ≦ 1. S = 0 indicates a completely random state such as a liquid state. S = 1 indicates a state where there is no molecular fluctuation and the crystal is completely oriented in one direction as in a crystal.

  The order parameter S can be measured by a conventionally known measurement method such as polarization Raman spectroscopy, polarization absorption measurement, polarized infrared spectroscopy, ellipsometry spectroscopy, etc. S is a value obtained by the above-described polarization Raman spectroscopy.

The “degree of orientation order” in the present specification is measured by the measurement method described in JP-A-2007-256438 as described above. Specifically, using “Nanofinder” manufactured by Tokyo Instruments Inc., the excitation laser wavelength is set to 532 nm, the excitation laser output is set to about 400 uW at the sample portion, and measurement is performed by attaching a depolarizer in front of the spectrometer. Value. As a measurement sample, the film to be measured is about 1 with respect to the film surface.
Use an angle cut at an angle of 2 degrees. Laser polarized light is incident on the sample, and polarization Raman measurement near the air interface of the optically anisotropic layer is performed. Rotate the sample, change the angle between the direction of the surface of the sample on which the laser polarized light is incident and the direction of the electric field of the incident laser polarized light, and measure at several angles. The scattered light components are parallel to the incident laser polarized electric field. A polarized light component (I perpendicular) to a polarized light component (I parallel) is spectroscopically detected using an analyzer. Further, for a band having a peak derived from the molecular skeleton contained in the layer, a fitting analysis based on the least square method is performed by using the orientation order parameters P2 and P4 as parameters by a theoretically derived expression, and the order parameter S is obtained. be able to.

  Here, various methods can be applied to the method for reducing the order parameter, but in this embodiment, the steps for producing the quarter-wave retardation layer 18 and the half-wave retardation layer 19 are used. In FIG. 7, by irradiation with ultraviolet rays in an oxygen-containing atmosphere (meaning including an air atmosphere, meaning that an inert gas purge such as nitrogen is not performed) (by ultraviolet irradiation by an ultraviolet irradiation device denoted by reference numeral 41 in FIG. 7) The phase difference layers 18 and 19 are produced by reducing the order parameter and setting the order parameter between 0.35 and 0.55.

  According to the above configuration, the transfer film according to the circularly polarizing plate, which forms the 1/4 retardation plate by laminating the 1/2 wavelength retardation layer 19 and the 1/4 wavelength retardation layer 18 by the adhesive layer 20, the optical film In the film, the retardation drop can be practically reduced by reducing the order parameter and producing the ½ wavelength retardation layer 19 and the ¼ wavelength retardation layer 18.

  Further, by reducing the order parameter by polymerizing the polymerizable liquid crystal monomer by irradiation with ultraviolet rays in the air atmosphere, the retardation drop can be sufficiently reduced practically with a simple configuration that effectively utilizes existing equipment.

[Second Embodiment]
In this embodiment, instead of polymerizing the polymerizable liquid crystal monomer by irradiation of ultraviolet rays in an oxygen-containing atmosphere and reducing the order parameter, the ultraviolet rays are preferably heated in a non-oxygen atmosphere environment such as a nitrogen purge. To reduce the order parameter. This embodiment has the same configuration as that of the first embodiment except that the order parameter reduction method is different.

  More specifically, in this embodiment, the lower limit is preferably the phase transition temperature to the isotropic phase minus 30 ° C. or higher, specifically preferably 50 ° C. or higher, preferably 60 ° C. or higher, and the upper limit is the base The polymerizable liquid crystal monomer is polymerized by irradiating with ultraviolet rays at a temperature not higher than the glass transition temperature (Tg) of the material, specifically preferably not higher than 70 ° C., whereby the order parameter is not lower than 0.35 and not higher than 0.55. The phase difference layers 18 and 19 are produced.

  According to this embodiment, the same effect as that of the first embodiment can be obtained even if the order parameter is reduced by irradiating ultraviolet rays while heating. In addition, you may combine with the oxygen containing atmosphere of 1st Embodiment.

[Other Embodiments]
The specific configuration suitable for the implementation of the present invention has been described in detail above. However, the present invention can be variously combined or modified with the configuration of the above-described embodiment without departing from the spirit of the present invention. Can do.

  That is, in the above-described embodiment, the case where the alignment films 22 and 23 are included in the transfer layer and function as a protective layer has been described. However, the present invention is not limited to this, and the alignment films 22 and 23 are excluded from the transfer layer. Also good.

  In the above-described embodiment, the case where the alignment films 22 and 23 are produced by transferring the fine line shape by the shaping process has been described. However, the present invention is not limited to this, and the alignment film is produced by a so-called photo-alignment technique. In this case, the present invention can be widely applied to the case where an alignment film is formed by the shape of the surface of the substrate by direct rubbing treatment of the substrate.

  Moreover, although the case where this invention was applied to a circularly-polarizing plate was described in the above-mentioned embodiment, this invention is not limited to this, It can apply widely to various optical films, such as a pattern phase difference film.

  In the above-described embodiment, the case where an optical film is produced by a transfer method has been described. However, the present invention is not limited to this, and an optical film is produced by directly producing an alignment film and a retardation layer on a substrate. It can be widely applied to cases. That is, for the circularly polarizing plates according to the first and second embodiments, on one side of the substrate made of a transparent film, an alignment film for a quarter wavelength retardation layer, a quarter wavelength retardation layer, a half wavelength position An alignment film for a retardation layer and a ½ wavelength retardation layer may be sequentially formed and bonded to a linearly polarizing plate, and for both a ½ wavelength retardation layer and a ¼ wavelength retardation layer on both sides. Each of the above configurations may be provided and bonded to the linear polarizing plate, and can be widely applied to these configurations.

  FIG. 9 is a diagram showing the results of studying retardation drops. In FIG. 9, Example 1 is one in which an order parameter is reduced by polymerizing a polymerizable liquid crystal monomer by irradiation with ultraviolet rays in an air atmosphere. In Example 1, a thinner-based photo-alignment material film is laminated with a film thickness of 100 nm on a substrate made of a TAC film having a thickness of 80 μm, and an alignment film is produced by irradiation with linearly polarized ultraviolet rays. The layer coating solution was applied. This coating liquid is a liquid crystal ink obtained by diluting a mixture of a photoinitiator (Irgacure 907) of 3 wt% and the following polymerizable rod-like liquid crystal monomer (phase transition point 100 ° C.) of 97 wt% with an organic solvent, and has a dry thickness. Was laminated to 1.5 μm, dried at 70 ° C., and heated to 105 ° C. for orientation. Thereafter, before the crystallization occurred, unpolarized ultraviolet rays were irradiated in an oriented state at 30 ° C. in an atmospheric environment, and a liquid crystal monomer was polymerized to prepare a retardation film A. The in-plane retardation was 142 nm, and the order parameter S determined by the polarization absorption measurement was 0.41.

  In Example 2, the order parameters were reduced by irradiating ultraviolet rays while heating in an environment purged with nitrogen. In Example 2, an alignment film was prepared on a substrate made of a TAC film under the same conditions as in Example 1, and then a retardation layer coating solution was applied. Thereafter, the film was dried at 70 ° C., heated to 105 ° C., and then kept at 70 ° C., irradiated with non-polarized ultraviolet rays under a nitrogen purge to polymerize the liquid crystal monomer, thereby producing a retardation film B. The in-plane retardation was 140 nm, and the order parameter S determined by the polarization absorption measurement was 0.39.

  In Comparative Example 1, a retardation film C was prepared by polymerizing a liquid crystal monomer by irradiating non-polarized ultraviolet light under a nitrogen purge instead of polymerizing a polymerizable liquid crystal monomer by irradiation with ultraviolet light in an air atmosphere. The configuration is the same as that of the first embodiment. The in-plane retardation was 148 nm, and the order parameter S determined by the polarization absorption measurement was 0.68.

  These retardation films A, B, and C were attached to a plate glass with an adhesive layer, and allowed to stand for 72 hours at 60 ° C. and 80 RH%, and the change in retardation value was measured. Among these Examples 1, 2 and Comparative Examples, the change in retardation value was the largest in Comparative Example 1, and in Examples 1 and 2, it was confirmed that the change in retardation value was small in each stage as compared with the Comparative Example. We were able to.

2, 15A, 24, 25 Base material 3, 23 Alignment film for 1/2 wavelength retardation layer (alignment film)
4, 19 1/2 wavelength retardation layer 5, 22 Alignment film for 1/4 wavelength retardation layer (alignment film)
6, 18 1/4 wavelength retardation layer 7, 16 1/4 wavelength plate 11, 71 Image display device 12 Image display panel 13, 73 Optical film 14 Adhesive layer 15 Linearly polarizing plate 15B Optical functional layer 17, 20 Adhesive layer 21 Transfer film 31 Supply reel 32, 39 Die 33, 40 Drying furnace 34, 44 Roll plate 35, 37 Roller 36, 41 Ultraviolet irradiation device 42 Take-up reel

Claims (6)

A method for producing a transfer body for an optical film comprising a support substrate and a transfer layer,
An alignment film production step of producing an alignment film on the substrate according to the support substrate;
A phase difference of a polymerizable liquid crystal which gives a phase difference of λ / 4 or λ / 2 to transmitted light by laminating a polymerizable liquid crystal monomer of a rod-like liquid crystal type on the alignment film and curing it. And a step of producing a retardation layer for producing a layer,
The transfer layer is at least a retardation layer of a polymerizable liquid crystal,
The step of producing the retardation layer includes
A coating process for coating the polymerizable liquid crystal monomer coating liquid on the alignment film;
A drying step of drying the coating liquid coated on the alignment film;
An ultraviolet irradiation step of producing a retardation layer of the polymerizable liquid crystal by polymerizing the polymerizable liquid crystal monomer provided on the alignment film by irradiation of ultraviolet rays;
With
In the ultraviolet irradiation step, the polymerizable liquid crystal monomer is polymerized by irradiating ultraviolet rays in an oxygen-containing atmosphere, and a retardation layer of the polymerizable liquid crystal having an order parameter of 0.35 to 0.55 is prepared.
A method for producing a transfer body for optical films. In the ultraviolet irradiation step, the polymerizable liquid crystal monomer is polymerized by irradiating ultraviolet rays at a temperature of 50 ° C. or more and a glass transition temperature (Tg) of the support substrate or less.
The manufacturing method of the transfer body for optical films of Claim 1. An alignment film creating step for a 1/2 wavelength retardation layer for creating an alignment film for a 1/2 wavelength retardation layer according to a 1/2 wavelength retardation layer on a first substrate;
By laminating a polymerizable liquid crystal monomer , which is a rod-like liquid crystal and a radical polymerization method, on the alignment film for the ½ wavelength phase difference layer, a phase difference corresponding to ½ wavelength is given to the transmitted light. A 1/2 wavelength retardation layer creating step of creating a 1/2 wavelength retardation layer;
An alignment film creating step for a quarter wavelength retardation layer for creating an alignment film for a quarter wavelength retardation layer according to a quarter wavelength retardation layer on a second substrate;
By laminating a polymerizable liquid crystal monomer , which is a rod-like liquid crystal and a radical polymerization method, on the alignment film for the quarter wavelength retardation layer, a phase difference corresponding to a quarter wavelength is imparted to transmitted light. A quarter wavelength retardation layer creating step for creating a quarter wavelength retardation layer;
A bonding step of bonding the half-wave retardation layer and the quarter-wave retardation layer with an adhesive layer;
The 1/4 wavelength retardation layer creation step and the 1/2 wavelength retardation layer creation step are:
A coating step of applying a coating liquid of the polymerizable liquid crystal monomer on the alignment film for the ¼ wavelength retardation layer and the alignment film for the ½ wavelength retardation layer;
A drying step for drying the coating liquid applied on the alignment film for the ¼ wavelength retardation layer and the alignment film for the ½ wavelength retardation layer;
The polymerizable liquid crystal monomer provided on the alignment film for the ¼ wavelength retardation layer and the alignment film for the ½ wavelength retardation layer is polymerized by irradiation with ultraviolet rays to form the ¼ wavelength position. An ultraviolet irradiation step for producing a retardation layer and the half-wave retardation layer;
With
In the ultraviolet irradiation step, the polymerizable liquid crystal monomer is polymerized by irradiating ultraviolet rays in an oxygen-containing atmosphere, and the quarter-wave retardation layer having an order parameter of 0.35 to 0.55 and the 1/2 The manufacturing method of the transfer body for optical films which produces a wavelength phase difference layer. In the ultraviolet irradiation step, the polymerizable liquid crystal monomer is polymerized by irradiating ultraviolet rays at a temperature of 50 ° C. or more and a glass transition temperature (Tg) of the substrate or less.
The manufacturing method of the transfer body for optical films of Claim 3. An alignment film production step of producing an alignment film on a substrate made of a transparent film;
A phase difference of a polymerizable liquid crystal which gives a phase difference of λ / 4 or λ / 2 to transmitted light by laminating a polymerizable liquid crystal monomer of a rod-like liquid crystal type on the alignment film and curing it. And a step of producing a retardation layer for producing a layer,
The step of producing the retardation layer includes
A coating process for coating the polymerizable liquid crystal monomer coating liquid on the alignment film;
A drying step of drying the coating liquid coated on the alignment film;
An ultraviolet irradiation step of producing a retardation layer of the polymerizable liquid crystal by polymerizing the polymerizable liquid crystal monomer provided on the alignment film by irradiation of ultraviolet rays;
With
In the ultraviolet irradiation step, the polymerizable liquid crystal monomer is polymerized by irradiating ultraviolet rays in an oxygen-containing atmosphere, and a retardation layer of the polymerizable liquid crystal having an order parameter of 0.35 to 0.55 is prepared.
Manufacturing method of optical film. In the ultraviolet irradiation step, the polymerizable liquid crystal monomer is polymerized by irradiating ultraviolet rays at a temperature of 50 ° C. or more and a glass transition temperature (Tg) of the substrate or less.
The manufacturing method of the optical film of Claim 5.

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