JP6217171B2 - Optical film transfer body, optical film, and image display device - Google Patents

Description

  The present invention relates to an optical film in which, for example, a quarter wavelength plate is formed by stacking a half wavelength retardation layer and a quarter wavelength retardation layer.

  Conventionally, regarding an image display device, a method has been proposed in which an optical film made of a circularly polarizing plate is arranged on the panel surface (viewer side surface) of an image display panel, and reflection of extraneous light is reduced by this optical film. Here, this optical film is composed of a laminate of a linear polarizing plate and a quarter-wave plate, and converts external light directed to the panel surface of the image display panel into linearly-polarized light by the linear polarizing plate, followed by a quarter-wave plate. Convert to circularly polarized light. 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, this reflected light is converted into linearly polarized light in the direction shielded by the linear polarizing plate by the ¼ wavelength plate, contrary to the arrival time, and then shielded by the subsequent linear polarizing plate. Outgoing emission is significantly suppressed.

  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.

  The half-wave retardation layer, the quarter-wave retardation layer, and the like can be created by solidifying (curing) the liquid crystal material in a state where the liquid crystal material is aligned by the alignment regulating force of the alignment film. . More specifically, this type of retardation layer is formed by laminating a polymerizable liquid crystal monomer on an alignment film, raising the temperature to the phase transition point, and then polymerizing by ultraviolet irradiation or the like to fix the alignment state of the liquid crystal. It is produced by. 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.

  By the way, after a ½ wavelength phase difference layer and a ¼ wavelength phase difference layer are individually formed, and then bonded together by an adhesive layer, a ½ wavelength phase difference layer and a ¼ wavelength phase difference layer are laminated. It is thought that a quarter wave plate can be produced by the body. At this time, it is considered that the entire thickness can be reduced by directly bonding the ½ wavelength retardation layer and the ¼ wavelength retardation layer with the adhesive layer.

  However, when the retardation layer is bonded together with an adhesive layer or the like in this way, there is a problem that the retardation value of the retardation layer gradually decreases, and the intended optical characteristics cannot be secured. Hereinafter, such a decrease in retardation value is referred to as retardation drop.

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

  The present invention has been made in view of such circumstances, and enables retardation retardation of the retardation layer to be reduced when the retardation device is bonded by an adhesive layer or the like.

  The present inventor has made extensive studies to solve the above-mentioned problems, and arrived at the idea of reducing the residual solvent component of the adhesive layer, thereby completing the present invention.

(1) A transfer body for an optical film comprising a support substrate and a transfer layer,
The transfer layer is
At least a ¼ wavelength phase difference layer that imparts a phase difference corresponding to ¼ wavelength to transmitted light, an adhesive layer or an adhesive layer, and a ½ that imparts a phase difference corresponding to ½ wavelength to transmitted light. A wavelength retardation layer,
By the adhesive layer or the pressure-sensitive adhesive layer, the ½ wavelength retardation layer and the ¼ wavelength retardation layer are bonded and held,
The adhesive layer or pressure-sensitive adhesive layer is
The amount of residual solvent is 1 mg / m ² or more and 5 mg / m ² or less.

  According to (1), a decrease in the retardation value due to the residual solvent can be reduced, thereby reducing the retardation drop.

  (2) In (1), the residual solvent of the ¼ wavelength retardation layer and / or the ½ wavelength retardation layer and the residual solvent of the adhesive layer or the pressure-sensitive adhesive layer contain the same solvent. Film transfer body.

  According to (2), the retardation drop can be more effectively reduced in the optical film using the optical film transfer body of (1).

(3) An optical film formed by bonding a transfer layer with an adhesive to a transfer substrate provided with a substrate made of at least a transparent film,
The transfer layer is the transfer layer of the optical film transfer body according to (1) or (2).

  According to (3), the retardation drop can be reduced in the optical film using the optical film transfer body of (1) or (2).

(4) 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
1/4 wavelength phase difference layer for imparting phase difference of 1/4 wavelength to transmitted light, adhesive layer or pressure-sensitive adhesive layer, and 1/2 wavelength for providing phase difference of 1/2 wavelength to transmitted light A retardation layer,
By the adhesive layer or the pressure-sensitive adhesive layer, the 1/2 wavelength retardation layer and the 1/4 wavelength retardation layer are bonded together,
The adhesive layer or pressure-sensitive adhesive layer is
The amount of residual solvent is 1 mg / m ² or more and 5 mg / m ² or less.

  According to (4), the retardation drop can be reduced with respect to the circularly polarizing plate produced by bonding the ½ wavelength retardation layer and the ¼ wavelength retardation layer by the adhesive layer and the pressure-sensitive adhesive layer.

  (5) The optical film described in (3) or (4) is disposed on the panel surface of the image display panel.

  According to (5), the image display apparatus by the optical film which reduced the retardation drop can be provided.

  The present invention can reduce a decrease in retardation value when a retardation layer is bonded by an adhesive layer.

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 graph which shows the examination result of the amount of residual solvents. It is a figure where it uses for description of the transfer film which concerns on 2nd Embodiment of this invention.

[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. In this embodiment, an ultraviolet curable resin applied to the preparation of the alignment film is applied. In the present invention, the adhesive layer 20 may be an adhesive layer.

  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. . Note that a material having relatively low adhesion to the support film (high peelability) and high adhesion to the release layer (low peelability) can be applied to the release layer. 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, after this process, the support base material 25 is peeled off from the optical film 13 (FIG. 6A), and then the adhesive layer 14 and the separator film are arranged to 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, when the 1/4 wavelength phase difference layer 18 and the 1/2 wavelength phase difference layer 19 are bonded together by the adhesive layer 20 to form a 1/4 wavelength plate, the 1/4 wavelength phase difference layer 18, 1 / There is a possibility that retardation drop occurs in the two-wavelength retardation layer 19. Therefore, in this embodiment, the amount of residual solvent in the adhesive layer 20 is reduced by setting the drying process for the adhesive layer 20 (FIG. 8, setting of the drying furnace 56), thereby reducing the retardation drop. More specifically, in this embodiment set the temperature in the drying oven 56, by the control of such conveying speed, the residual solvent amount was set to 5 mg / m ² or less, more preferably a residual solvent content to 2 mg / m ² or less This reduces retardation drops. If the residual solvent amount is significantly reduced, the base materials 24 and 25 are deformed due to thermal damage to the base materials 24 and 25, so that the lower limit value of the residual solvent amount is 1 mg / m ² . Thereby, the residual solvent amount of the adhesive layer 20 is set to 5 mg / m ² or less, 1 mg / m ² or more, more preferably 2 mg / m ² or less, 1 mg / m ² or more to reduce the retardation value. Can do. The reason for this is not clear, but it is presumed that the solvent of the adhesive layer or the adhesive layer permeates the surface of the retardation layer and disturbs the alignment of the liquid crystal near the surface layer. The residual solvent amount in the present invention is a value measured by gas chromatography (GC) under the condition of heating at 120 ° C. for 120 minutes.

  The solvent type of the residual solvent is not particularly limited, such as MEK, toluene, ethyl acetate, and a mixture thereof, but this retardation drop is a 1/4 wavelength retardation layer 18, 1 from the viewpoint of permeability to the surface of the retardation layer. / When the organic solvent of the coating liquid used for the preparation of the two-wavelength retardation layer 19 and the organic solvent of the coating liquid used for the preparation of the adhesive layer 20 contain the same solvent, preferably the same solvent This is a particularly preferable embodiment.

FIG. 9 is a diagram illustrating the examination result of the retardation drop. In the study of FIG. 9, methyl ethyl ketone (methyl ethyl ketone, MEK, the same as the solvent of the retardation layer) is applied to the organic solvent related to the coating solution of the adhesive layer 20, and the residual solvent amount is changed by changing the conditions of the drying furnace 56. The change in retardation value was measured by variously changing. The residual solvent amount was measured by curing with irradiation of ultraviolet rays in a state where the adhesive layer 20 was formed. According to the results in the measurement of FIG. 9, if the residual solvent amount of the adhesive layer 20 is 5 mg / m ² , it is possible to prevent the retardation value from being sufficiently reduced practically, and the residual solvent amount is 2 mg / m 2. ^It can be seen that the retardation drop can be further reduced by setting it to ² or less.

  In this embodiment, when the retardation layer is bonded by an adhesive layer made of an ultraviolet curable resin, the retardation drop can be reduced by reducing the amount of residual solvent in the adhesive layer.

[Second Embodiment]
FIG. 10 is a diagram showing a manufacturing process according to the second embodiment of the present invention in comparison with FIG. This manufacturing process includes a base material 24, a ½ wavelength retardation layer alignment film 23, a laminate of the ½ wavelength retardation layer 19, and a base material 25, a ¼ wavelength retardation layer alignment film 22, The manufacturing process according to FIG. 10 is applied to the manufacturing process of the laminated body of the ¼ wavelength retardation layer 18, and the ½ wavelength retardation layer alignment film 23 and the ¼ wavelength retardation layer alignment film 22 are applied. Is made of a photo-alignment film. This embodiment has the same configuration as that of the first embodiment except that the configuration related to the photo-alignment film is different. In FIG. 10, a reference numeral is attached to an example in which the alignment film 23 for a half-wave retardation layer is formed of a photoalignment film.

  That is, in this embodiment, the base material 24 is pulled out from the supply reel 31, and the coating liquid related to the photo-alignment film is applied by the die 32. In the photo-alignment film, various materials such as a photodimerization type material and a photoisomerization reaction type photo-alignment material can be applied. In the coating method, various methods can be applied. In this step, the coating liquid is dried by the drying furnace 33, and then irradiated with linearly polarized ultraviolet rays in a predetermined polarization direction from the ultraviolet irradiation device 60, thereby forming the alignment film 23 for a ½ wavelength retardation layer. To do. Subsequently, in this step, after the liquid crystal material is applied by the die 39, the liquid crystal material is dried by the drying furnace 40, the liquid crystal material is cured by the ultraviolet irradiation by the ultraviolet irradiation device 41, and wound on the take-up reel 42. Similarly, a quarter-wave retardation layer alignment film 22 is formed.

  Even when the alignment film is formed by applying the photo-alignment technique as in this embodiment, the same effect as that of the first embodiment can be obtained.

[Third Embodiment]
In this embodiment, the retardation layers 18 and 19 are bonded with a PSA (Pressure Sensitive Adhesive) adhesive instead of the adhesive layer 20 made of an ultraviolet curable resin. Furthermore, regarding the bonding with this pressure-sensitive adhesive, the amount of residual solvent in the pressure-sensitive adhesive layer with this pressure-sensitive adhesive is 1 mg / m ² or more and 5 mg / m ² or less, preferably 1 mg / m ² or more and 2 mg / m ² or less. Reduce.

  In this embodiment, the same effect as that of the above-described embodiment can be obtained by applying to the case where the retardation layer is bonded with an adhesive.

[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.

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 (4)

A transfer body for an optical film comprising a support substrate and a transfer layer,
The transfer layer is
At least a ¼ wavelength phase difference layer that imparts a phase difference corresponding to ¼ wavelength to transmitted light, an adhesive layer or an adhesive layer, and a ½ that imparts a phase difference corresponding to ½ wavelength to transmitted light. A wavelength retardation layer,
The quarter-wave retardation layer and the half-wave retardation layer are
Formed by a polymerizable liquid crystal monomer,
By the adhesive layer or the pressure-sensitive adhesive layer, the ½ wavelength retardation layer and the ¼ wavelength retardation layer are bonded and held,
The residual solvent of the ¼ wavelength retardation layer and the ½ wavelength retardation layer, and the residual solvent of the adhesive layer or the pressure-sensitive adhesive layer,
Contains the same solvent,
The adhesive layer or pressure-sensitive adhesive layer is
The optical film for transfer body residual solvent amount measured by gas chromatography is 1 mg / ^{m 2} or more 2 mg / ^{m 2} or less under the conditions of heating for 120 minutes at 120 ° C.. An optical film formed by bonding a transfer layer with an adhesive to a transfer substrate provided with a substrate made of at least a transparent film,
The optical film of the transfer layer is the transfer layer of the optical film for transfer body according to claim 1. 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
1/4 wavelength phase difference layer for imparting phase difference of 1/4 wavelength to transmitted light, adhesive layer or pressure-sensitive adhesive layer, and 1/2 wavelength for providing phase difference of 1/2 wavelength to transmitted light A retardation layer,
The quarter-wave retardation layer and the half-wave retardation layer are
Formed by a polymerizable liquid crystal monomer,
By the adhesive layer or the pressure-sensitive adhesive layer, the 1/2 wavelength retardation layer and the 1/4 wavelength retardation layer are bonded together,
The residual solvent of the ¼ wavelength retardation layer and the ½ wavelength retardation layer, and the residual solvent of the adhesive layer or the pressure-sensitive adhesive layer,
Contains the same solvent,
The adhesive layer or pressure-sensitive adhesive layer is
Optical film residual solvent content as determined by gas chromatography under the conditions of heating for 120 minutes at 120 ° C. is 1 mg / ^{m 2} or more 2 mg / ^{m 2} or less. The image display apparatus which has arrange | positioned the optical film of Claim 3 on the panel surface of an image display panel.

Images