JP2008089894A - Method for manufacturing retardation filmmethod for manufacturing retardation film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a retardation film having a low haze. <P>SOLUTION: The method for manufacturing a retardation film includes: a layer forming step of forming a retardation layer, to form a layer 2A' for formation of a retardation layer on a transparent substrate by applying a UV-curing composition containing a crosslinking liquid crystal material having a crosslinking functional group and a photoreactive compound having a photoreactive group on the transparent substrate 1; an alignment imparting step of developing alignment property of the layer for formation of a retardation layer to the crosslinking liquid crystal material by irradiating the layer for formation of the retardation layer with polarized UV rays through one surface to allow the photoreactive compound to react; and a step of heating the layer for formation of the retardation layer in such a manner that the surface of the layer for formation of the retardation layer irradiated with the polarized UV rays reaches a crystal-liquid crystal phase transition temperature of the crosslinking liquid crystal material faster than the surface opposite to the surface irradiated with polarized UV rays. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a retardation film used in a liquid crystal display device or the like. More specifically, the present invention relates to a method for producing a retardation film having a transparent substrate and a retardation layer formed directly on the transparent substrate without an alignment film and containing a liquid crystalline material.

  The liquid crystal display device has features such as power saving, light weight, thinness, and the like, and has rapidly spread in recent years in place of the conventional CRT display. As a general liquid crystal display device, as shown in FIG. 3, a liquid crystal display device having an incident side polarizing plate 102 </ b> A, an outgoing side polarizing plate 102 </ b> B, and a liquid crystal cell 101 can be exemplified. The polarizing plates 102A and 102B are configured to selectively transmit only linearly polarized light (schematically illustrated by arrows in the figure) having a vibration surface in a predetermined vibration direction. They are arranged to face each other in a crossed Nicol state so as to have a right angle relationship with each other. The liquid crystal cell 101 includes a large number of cells corresponding to the pixels, and is disposed between the polarizing plates 102A and 102B.

  The liquid crystal display device has a problem of viewing angle characteristics as a peculiar defect. The problem of viewing angle characteristics is a problem in which contrast, color, and the like change between when the liquid crystal display device is viewed from the front and when viewed from an oblique direction. Such a problem is caused by the fact that the liquid crystal cell used in the liquid crystal display device has birefringence and has two polarizing plates arranged in crossed Nicols.

  Various techniques have been developed so far to improve the viewing angle characteristic. One of the typical methods is a method using a retardation film having a predetermined birefringence. This method using a retardation film is a method for improving viewing angle characteristics by disposing a retardation film exhibiting a predetermined birefringence between a liquid crystal cell and a polarizing plate in a liquid crystal display device. Such a method can improve the viewing angle dependency problem of a liquid crystal display device using a liquid crystal cell having various optical characteristics by using a retardation film having different birefringence according to the type of the liquid crystal cell. In this respect, it is useful in liquid crystal display devices that employ various display methods.

  As the retardation film, those having a substrate, an alignment film formed on the substrate, and a retardation layer formed on the alignment film and containing a liquid crystal material have been widely used. It was. In such a retardation film, the liquid crystal material is regularly arranged in the retardation layer in accordance with the alignment regulating force of the alignment film, so that a desired birefringence can be expressed.

  By the way, in recent years, a retardation film that does not require the alignment film as the retardation film, that is, a retardation film having a structure in which a retardation layer is directly formed on the substrate has been developed (Patent Document 1). And Patent Document 2). Such a retardation film that does not require an alignment film is capable of three-dimensional alignment of a liquid crystal material, which has been difficult to achieve with a retardation film using a conventional alignment film, and has a plurality of positions. It has an advantage that a retardation layer can be laminated, and furthermore, a manufacturing process of a retardation film can be simplified.

  However, when the retardation film which does not require an alignment film using a compound as disclosed in Patent Document 1 and Patent Document 2 is prepared, the retardation is compared with a retardation film using a conventional alignment film. There was a problem that the haze of the layer was increased.

  For these reasons, there is a problem that it is difficult to obtain a retardation film excellent in transparency in a retardation film that does not use an alignment film.

Special table 2002-517605 gazette JP 2002-82224 A

  The present invention has been made in view of the above problems, and is a retardation film having a transparent substrate and a retardation layer which is directly formed on the transparent substrate without an alignment film and contains a liquid crystalline material. The main object of the present invention is to provide a method for producing a retardation film capable of producing a retardation film having a small haze.

  In order to solve the above-mentioned problems, the present invention uses a transparent substrate, and contains a crosslinkable liquid crystal material having a crosslinkable functional group on the transparent substrate and a photoreactive compound having a photoreactive group. By applying the composition, the phase difference layer forming layer forming step for forming the phase difference layer forming layer on the transparent substrate, and the polarizing layer forming layer is irradiated with polarized ultraviolet rays from one side, An alignment imparting step for causing the retardation layer forming layer to exhibit alignment with respect to the crosslinkable liquid crystal material by reacting the photoreactive compound, and the polarized ultraviolet rays of the retardation layer forming layer were irradiated. The phase difference layer forming layer is heated so that the surface surface reaches the crystal-liquid crystal phase transition temperature of the crosslinkable liquid crystal material before the surface opposite to the surface irradiated with the polarized ultraviolet light. The crosslinkable liquid crystal material Providing a liquid crystal alignment step of the column, a method for producing a retardation film characterized by having a liquid crystal crosslinking step of crosslinking the crosslinkable liquid crystal material arranged by the liquid crystal aligning step.

According to the present invention, the orientation imparting step imparts the orientation to the retardation layer forming layer by irradiating the retardation layer forming layer with polarized ultraviolet light from one side, and In the liquid crystal alignment step, the surface of the phase difference layer forming layer irradiated with the polarized ultraviolet light has a crystal of the crosslinkable liquid crystal material before the surface opposite to the surface irradiated with the polarized ultraviolet light. -By aligning the crosslinkable liquid crystal material by heating the retardation layer forming layer so as to reach the liquid crystal phase transition temperature, the crosslinkable liquid crystal material is uniformly distributed in the liquid crystal alignment step. Can be arranged. For this reason, according to this invention, the phase difference film which has a phase difference layer with a small haze can be manufactured.
Therefore, according to the present invention, a retardation film having a transparent substrate and a retardation layer formed directly on the transparent substrate without an alignment film and containing a liquid crystalline material, A retardation film having a small haze can be produced.

  In the present invention, the photoreactive compound preferably has at least one photoreactive group represented by the following formulas (I) and (II). Since the photoreactive compound having a photoreactive group represented by the following formulas (I) and (II) is excellent in compatibility with the crosslinkable liquid crystal material, by using such a photoreactive compound, This is because a retardation film having a small haze can be produced.

In the above formulas (I) and (II), A ¹ , A ² , A ³ are each independently unsubstituted or optionally substituted with fluorine, chlorine, cyano, alkyl, alkoxy, or alkyloxycarbonyl. , 4-phenylene, 4,4′-biphenylene, 1,4-naphthylene, 2,6-naphthylene, pyridine-2,5-diyl, pyrimidine-2,5-diyl, 1,3-dioxane-2,5- Diyl, piperidine-1,4-diyl or piperazine-1,4-diyl is represented.
R ¹ represents hydrogen, alkyl having 1 to 4 carbons, or alkoxy having 1 to 4 carbons.
R ² represents hydrogen, alkyl having 1 to 4 carbon atoms, alkoxy having 1 to 4 carbon atoms, alkyloxycarbonyl having 2 to 6 carbon atoms, or cyano.
R ³ represents hydrogen, unsubstituted or alkyl having 1 to 20 carbon atoms substituted with any fluorine or chlorine.

  In addition, the present invention uses a transparent substrate, and coats an ultraviolet curable composition containing a liquid crystalline structural unit having liquid crystallinity in the molecule and a photoreactive polymer liquid crystal having a photoreactive group on the transparent substrate. A phase difference layer forming layer forming step for forming a phase difference layer forming layer on the transparent substrate, and irradiating the phase difference layer forming layer with polarized ultraviolet light from one side to form the photoreactive group. An orientation imparting step for causing the retardation layer forming layer to exhibit orientation with respect to the liquid crystalline structural unit by reacting, and a surface of the surface of the retardation layer forming layer that has been irradiated with the polarized ultraviolet rays, By heating the retardation layer forming layer so as to reach the glass phase-liquid crystal phase transition temperature of the photoreactive polymer liquid crystal before the surface opposite to the surface irradiated with polarized ultraviolet rays, Liquid crystal in which the liquid crystalline structural units are arranged It provides a method for producing a retardation film characterized by having a column step.

According to the present invention, the orientation imparting step imparts the orientation to the retardation layer forming layer by irradiating the retardation layer forming layer with polarized ultraviolet light from one side, and In the liquid crystal alignment step, the surface of the retardation layer forming layer irradiated with the polarized ultraviolet light has a surface opposite to the surface opposite to the surface irradiated with the polarized ultraviolet light. The liquid crystalline structural units are aligned in the liquid crystal aligning step by heating the retardation layer forming layer so as to reach a glass phase-liquid crystal phase transition temperature of Can be arranged uniformly. For this reason, according to this invention, the phase difference film which has a phase difference layer with a small haze can be manufactured.
Therefore, according to the present invention, a retardation film having a transparent substrate and a retardation layer formed directly on the transparent substrate without an alignment film and containing a liquid crystalline material, A retardation film having a small haze can be produced.

  In this invention, it is preferable that the said liquid crystal aligning process heats the said layer for phase difference layer formation only from the surface side irradiated with the said polarized ultraviolet rays in the said orientation provision process. Thereby, in the liquid crystal alignment step, the cross-linkability of the surface of the retardation layer forming layer on the surface irradiated with the polarized ultraviolet light is earlier than the surface opposite to the surface irradiated with the polarized ultraviolet light. This is because it is easy to heat the retardation layer forming layer so as to reach the crystal-liquid crystal phase transition temperature of the liquid crystal material or the glass phase-liquid crystal phase transition temperature of the photoreactive polymer liquid crystal. .

  In the present invention, the orientation imparting step may irradiate the retardation layer forming layer with polarized ultraviolet light from the side opposite to the transparent substrate of the retardation layer forming layer. preferable. This is because it becomes easy to impart a uniform orientation regulating force to the retardation layer forming layer in the orientation imparting step.

  The present invention is a retardation film having a transparent substrate and a retardation film formed directly on the transparent substrate without an alignment film and containing a liquid crystalline material, and producing a retardation film having a small haze. There is an effect that can be done.

  Hereinafter, the manufacturing method of the retardation film of this invention is demonstrated.

  The method for producing a retardation film of the present invention can be broadly divided into two modes depending on the composition of the retardation layer forming coating solution used in the retardation layer forming layer forming step. Therefore, hereinafter, the method for producing the retardation film of the present invention will be described separately for each embodiment.

A. First, a method for producing the retardation film of the first aspect will be described. The method for producing a retardation film according to this aspect includes a retardation layer forming coating solution containing a crosslinkable liquid crystal material having a crosslinkable functional group and a photoreactive compound having a photoreactive group. This is the mode of use.
That is, the method for producing a retardation film of this embodiment uses a transparent substrate, and contains a crosslinkable liquid crystal material having a crosslinkable functional group on the transparent substrate and a photoreactive compound having a photoreactive group. By applying the curable composition, a retardation layer forming layer forming step for forming a retardation layer forming layer on the transparent substrate, and the polarizing layer forming layer is irradiated with polarized ultraviolet rays from one side. , By applying the photoreactive compound to the retardation layer forming layer, the orientation imparting step for expressing the orientation with respect to the crosslinkable liquid crystal material, and the polarized ultraviolet rays of the retardation layer forming layer are irradiated. The retardation layer forming layer is heated so that the surface of the surface reaches the crystal-liquid crystal phase transition temperature of the crosslinkable liquid crystal material before the surface opposite to the surface irradiated with the polarized ultraviolet light. The above crosslinkability A liquid crystal alignment step of aligning the crystal material, is characterized in that it has a liquid crystal crosslinking step of crosslinking the crosslinkable liquid crystal material arranged by the liquid crystal aligning step.

  The method for producing the retardation film of this embodiment will be described with reference to the drawings. FIG. 1 is a schematic view showing an example of a method for producing a retardation film of this embodiment. As illustrated in FIG. 1, the method for producing a retardation film of this embodiment uses a transparent substrate 1 (FIG. 1A), a crosslinkable liquid crystal material having a crosslinkable functional group on the transparent substrate 1, and light. Retardation layer forming layer forming step of forming a retardation layer forming layer 2A ′ on the transparent substrate 1 by coating an ultraviolet curable composition containing a photoreactive compound having a reactive group. (FIG. 1B) and the retardation layer forming layer 2A ′ are irradiated with polarized ultraviolet rays from the opposite surface (A) side to the transparent substrate 1 to cause the photoreactive compound to react. , An orientation imparting step (FIG. 1 (c)) for causing the retardation layer forming layer 2A ′ to exhibit orientation with respect to the crosslinkable liquid crystal material, and the transparent substrate 1 of the retardation layer forming layer 2A ′. The surface (A) on the opposite side is above the surface (B) on the transparent substrate 1 side. A liquid crystal alignment step (FIG. 1 (d)) for aligning the crosslinkable liquid crystal material by heating the retardation layer forming layer 2A ′ so as to reach the crystal-liquid crystal phase transition temperature of the crosslinkable liquid crystal material; The liquid crystal cross-linking step (FIG. 1 (e)) for cross-linking the cross-linkable liquid crystal material arranged in the liquid crystal aligning step, and the retardation layer 2A directly formed on the transparent substrate 1 10A is produced (FIG. 1 (f)).

  According to the present invention, the orientation imparting step imparts the orientation to the retardation layer forming layer by irradiating the retardation layer forming layer with polarized ultraviolet light from one side, and In the liquid crystal alignment step, the surface of the phase difference layer forming layer irradiated with the polarized ultraviolet light has a surface of the crosslinkable liquid crystal material prior to the surface opposite to the surface irradiated with the polarized ultraviolet light. The crosslinkable liquid crystal material is aligned by heating the retardation layer forming layer so as to reach a crystal-liquid crystal phase transition temperature, so that the crosslinkable liquid crystal material is uniformly distributed in the liquid crystal alignment step. Can be arranged. For this reason, according to this invention, the phase difference film which has a phase difference layer with a small haze can be manufactured.

Here, the reason why the retardation layer in which the crosslinkable liquid crystal material is uniformly arranged can be formed by having the alignment imparting step and the liquid crystal alignment step as described above is not clear. It is thought to be due to.
That is, in the orientation imparting step, the retardation layer forming layer is irradiated with polarized ultraviolet rays to cause the photoreactive compound contained in the retardation layer forming layer to react to impart orientation. It is. Here, since the photoreactive compound is capable of expressing a more uniform alignment regulating force when irradiated with polarized ultraviolet rays having a high degree of polarization, the polarized ultraviolet rays are irradiated in the orientation imparting step. The surface of the formed surface becomes a region where the most uniform orientation regulating force can be expressed.
For this reason, in the liquid crystal alignment step, the surface of the surface irradiated with the polarized ultraviolet light reaches the crystal-liquid crystal phase transition temperature of the crosslinkable liquid crystal material before the surface on the opposite side. By heating the phase difference layer forming layer, the crosslinkable liquid crystal material can be arranged according to a uniform alignment regulating force at an initial stage where the crosslinkable liquid crystal material is arranged.
Here, the crosslinkable liquid crystal material has a property that when the crosslinkable liquid crystal material present in a certain portion is aligned, the crosslinkable liquid crystal material present in the other portion is aligned along the alignment. For this reason, in the liquid crystal alignment step, when a uniform alignment can be formed at the initial stage where the crosslinkable liquid crystal material is aligned, then the crosslinkable liquid crystal present in other portions along the uniform alignment. It is possible to arrange the materials uniformly in a chained manner.
For this reason, the retardation film produced according to the present aspect can be obtained by forming the crosslinkable liquid crystal material in a uniform arrangement over the entire retardation layer. It is thought that it can be made small.

  From the above, according to this aspect, a retardation film having a transparent substrate and a retardation layer formed directly on the transparent substrate without an alignment film and containing a liquid crystalline material, A retardation film having a small haze can be produced.

The method for producing a retardation film according to this aspect includes at least the layer forming step for forming a retardation layer, the orientation imparting step, the liquid crystal alignment step, and the liquid crystal crosslinking step. May have other processes.
Hereinafter, each process used for the manufacturing method of the retardation film of this aspect is demonstrated in order.

1. Liquid Crystal Alignment Step First, the liquid crystal alignment step used in this embodiment will be described. In this step, the layer for forming the retardation layer formed in the layer forming step for forming the retardation layer, which will be described later, the surface of the surface irradiated with polarized ultraviolet rays in the orientation providing step described later is more than the surface on the opposite side. This is a step of arranging the crosslinkable liquid crystal material by first heating to reach the crystal-liquid crystal phase transition temperature of the crosslinkable liquid crystal material.
In the method for producing a retardation film of this embodiment, this step is to arrange the crosslinkable liquid crystal material by such a method, whereby a retardation film having a small haze can be produced.
Hereinafter, such a liquid crystal alignment process will be described in detail.

As described above, this step is a step of aligning the crosslinkable liquid crystal material by heating the phase difference layer forming layer. As a heating method used in this step, the orientation imparting is performed. A method in which the retardation layer forming layer can be heated so that the surface irradiated with polarized ultraviolet rays in the process reaches the crystal-liquid crystal phase transition temperature of the crosslinkable liquid crystal material before the opposite surface. If it is, it will not specifically limit. As such a heating method, heating is performed from both sides of the retardation layer forming layer, and the heating temperature for the surface irradiated with the polarized ultraviolet light is set higher than the heating temperature for the opposite surface. And a method of heating the retardation layer forming layer only from the side irradiated with the polarized ultraviolet light. In this step, any of these heating methods can be preferably used, but the latter heating method is particularly preferable. By using a method in which the phase difference layer forming layer is heated only from the surface side irradiated with the polarized ultraviolet light, the surface of the surface irradiated with the polarized ultraviolet light is the surface irradiated with the polarized ultraviolet light. This is because it is easy to heat the retardation layer forming layer so as to reach the crystal-liquid crystal phase transition temperature of the crosslinkable liquid crystal material before the surface on the opposite side.
In addition, when using the method of heating the phase difference layer forming layer only from the surface side irradiated with the polarized ultraviolet light, the surface opposite to the surface irradiated with the polarized ultraviolet light is cooled and the opposite side is cooled. You may suppress the temperature rise of the surface.

  The method of heating the retardation layer forming layer only from the side irradiated with polarized ultraviolet rays is particularly limited as long as the surface irradiated with polarized ultraviolet rays can be heated to a predetermined temperature. is not. As such a heating method, for example, a method of blowing warm air on the surface irradiated with the polarized ultraviolet light, a method of bringing a hot plate close to the surface irradiated with the polarized ultraviolet light, and a surface irradiated with the polarized ultraviolet light The method etc. which install an infrared heater or a far-infrared heater in the side of this can be mentioned.

  In addition, when the retardation layer forming layer is heated only from the side irradiated with polarized ultraviolet rays, the heat from the heat source for heating the surface irradiated with polarized ultraviolet rays wraps around the opposite side surface. The surface opposite to the surface irradiated with polarized ultraviolet light may be covered with a heat insulating member, or the surface opposite to the surface irradiated with polarized ultraviolet light may be cooled.

  In this step, the temperature (referred to as Tt) for heating the surface irradiated with polarized ultraviolet light is not less than the crystal-liquid crystal phase transition temperature (referred to as Tm) of the crosslinkable liquid crystal material, and The crosslinkable liquid crystal material has a temperature lower than the liquid crystal phase-isotropic phase transition temperature (referred to as Ti) and irradiated with the polarized ultraviolet light within a predetermined time. The temperature is not particularly limited as long as it can reach the liquid crystal phase transition temperature. Such a heating temperature can be appropriately determined according to the crystal-liquid crystal phase transition temperature (Tm) and the liquid crystal phase-isotropic phase transition temperature (Ti) of the crosslinkable liquid crystal material. Especially in this process, it is preferable that the said heating temperature (Tt) is in the range of (Tm + 5) (° C.) ≦ Tt (° C.) <Ti (° C.). When the heating temperature (Tt) in this step is Tm (° C.) ≦ Tt (° C.) <(Tm + 5) (° C.), the cross-linkable liquid crystal is irradiated on the surface irradiated with the polarized ultraviolet rays within a desired time. This is because it may be difficult to heat to the crystal-liquid crystal phase transition temperature of the material.

2. Orientation imparting step Next, the orientation imparting step used in this step will be described. In this step, the photoreactive compound contained in the retardation layer forming layer is obtained by irradiating the retardation layer forming layer formed by the retardation layer forming layer, which will be described later, with polarized ultraviolet rays from one side. Is a step of causing the retardation layer forming layer to exhibit orientation with respect to the crosslinkable liquid crystal material.
Hereinafter, such an orientation imparting step will be described in detail.

This step is to impart orientation to the retardation layer forming layer by irradiating polarized ultraviolet rays from one side of the retardation layer forming layer. The surface of the phase difference layer forming layer may be the surface on the transparent substrate side or the surface on the opposite side to the transparent substrate side. In particular, in this step, it is preferable to irradiate the retardation layer forming layer with polarized ultraviolet rays from the surface of the retardation layer forming layer on the side opposite to the transparent substrate. This is due to the following reason.
That is, when irradiating polarized ultraviolet rays to the surface on the transparent substrate side, the polarized ultraviolet rays are irradiated to the retardation layer forming layer through the transparent substrate. Here, when the polarized ultraviolet light passes through the transparent substrate, the polarized ultraviolet light is absorbed or scattered by the transparent substrate, and the intensity of the ultraviolet light is reduced or the polarized light is relaxed. There is a risk that it may be difficult to impart uniform orientation. On the other hand, when irradiating polarized ultraviolet rays from the surface opposite to the transparent substrate, such a situation does not occur. Therefore, in this step, it is easy to impart a uniform alignment regulating force to the retardation layer forming layer. Because it becomes.

  In this step, the polarized ultraviolet ray irradiated to the retardation layer forming layer has a wavelength that can cause a photoreaction of the photoreactive group of the photoreactive compound, and the crosslinkable liquid crystal material. There is no particular limitation as long as it is within a range in which the crosslinkable functional group has a crosslink formation reaction hardly occurring. Such polarized ultraviolet rays can be appropriately selected and used according to the types of the photoreactive group and the crosslinkable functional group.

In this step, the method for irradiating the retardation layer forming layer with polarized ultraviolet light is not particularly limited as long as it can irradiate the retardation layer forming layer with polarized ultraviolet light in a desired vibration direction. As such a method, a method of using a light source that oscillates ultraviolet rays having a wavelength in the above range and irradiating non-polarized ultraviolet rays oscillated from the light source to the retardation layer forming layer through a polarizer is used. It is done.
At this time, the vibration direction of the polarized ultraviolet light applied to the retardation layer forming layer can be changed by changing the direction of the absorption axis of the polarizer.

  Examples of the polarizer include a Glan-Thompson prism, a Grand Taylor prism, a polarizing film containing a dichroic dye, a Brewster plate polarizer, and a wire grid polarizer.

  Examples of the light source include an ultrahigh pressure mercury lamp, a medium pressure mercury lamp, a xenon lamp, a deuterium lamp, a halogen lamp, a deep UV lamp, and a fluorescent lamp.

  Furthermore, when irradiating polarized ultraviolet rays to the retardation layer forming layer in this step, a UV cut filter that shields ultraviolet rays having a specific wavelength may be used as necessary. By using such a UV cut filter, for example, the reaction of the photoreactive compound is prevented from being inhibited, or the crosslinking formation reaction of the crosslinkable liquid crystal material proceeds in this step. It is because it can prevent.

As a UV cut filter used in this step, for example, WG280 manufactured by SCHOTT can be mentioned as one used to prevent the reaction of the photoreactive compound from being inhibited.
Moreover, as what is used in order to prevent that the crosslinking formation reaction of the said crosslinkable liquid crystal material advances, when using the photoreactive compound whose maximum absorption wavelength is 270 nm-310 nm, for example, 325 nm- Examples thereof include a UV cut filter (manufactured by Asahi Spectroscopic Co., Ltd .: SU0325) that shields ultraviolet rays of 400 nm.

  In this step, the temperature of the retardation layer forming layer when the polarizing layer forming layer is irradiated with polarized ultraviolet light is preferably the non-liquid crystalline temperature of the crosslinkable liquid crystal material. Here, the non-liquid crystalline temperature usually means a temperature lower than the transition temperature from the crystal or glass phase to the liquid crystal phase and higher than the liquid crystal phase-isotropic phase transition temperature. It is preferably less than the transition temperature from the crystal or glass phase to the liquid crystal phase.

3. Next, the phase difference layer forming layer forming step used in this embodiment will be described. This step uses a transparent substrate, and coats an ultraviolet curable composition containing a crosslinkable liquid crystal material having a crosslinkable functional group and a photoreactive compound having a photoreactive group on the transparent substrate. To form a retardation layer forming layer on the transparent substrate.
Further, the retardation layer forming layer formed in this step is a retardation layer that develops retardation through the above-described liquid crystal alignment step, orientation imparting step, and liquid crystal crosslinking step described later. It is.
Hereinafter, the layer forming process for forming the retardation layer will be described in detail.

(1) Ultraviolet curable composition First, the ultraviolet curable composition used for this process is demonstrated. The ultraviolet curable composition used in this step contains a crosslinkable liquid crystal material having a crosslinkable functional group and a photoreactive compound having a photoreactive group.

a) Photoreactive compound As the photoreactive compound used in the ultraviolet curable composition, a phase difference layer forming layer is formed by this process by causing a photochemical reaction when irradiated with ultraviolet rays having a specific wavelength. If it has a photoreactive group which can provide the orientation with respect to the said crosslinkable liquid crystal material, it will not specifically limit. Examples of the photoreactive group of the photoreactive compound used in this step include cinnamate, coumarin, benzylidenephthalimidine, benzylideneacetophenone, diphenylacetylene, stilbazole, uracil, quinolinone, maleinimide, or cinnamylideneacetic acid derivatives. Can be mentioned.

  As the photoreactive compound used in this step, any photoreactive compound having any of the above-mentioned photoreactive groups can be suitably used, and among them, in the above formula (I) or (II) At least a photoreactive group represented (hereinafter, the photoreactive groups represented by the above formulas (I) and (II) may be referred to as a photoreactive group I and a photoreactive group II, respectively). It is preferable to use one photoreactive compound. Since the photoreactive compound having the photoreactive group I or the photoreactive group II is excellent in compatibility with a crosslinkable liquid crystal material described later, the use of such a photoreactive compound further increases the haze according to this embodiment. This is because it is possible to produce a retardation film having a small thickness.

Here, a retardation film having a smaller haze can be produced by using a compound having at least one of photoreactive group I or photoreactive group II as the photoreactive compound. This is thought to be due to such reasons.
That is, the crosslinkable liquid crystal material generally has a structure having a rigid part to which an aromatic ring structure is connected and a chain part that is bonded to the rigid part and includes a carbon-oxygen bond. is there. On the other hand, the photoreactive group I or the photoreactive group II has a structure in which at least two aromatic rings are connected, and is similar to the molecular structure of the rigid portion of the crosslinkable liquid crystal material. Have a high chemical structure.
For this reason, by using a photoreactive compound having at least one photoreactive group I or photoreactive group II as the photoreactive compound, the photoreactive compound, the crosslinkable liquid crystal material, Therefore, it is possible to form a retardation layer-forming layer having excellent transparency. As a result, a retardation film having a smaller haze can be produced.

  The photoreactive group I is not particularly limited as long as it has a structure represented by the above formula (I). The use of the retardation film produced according to this embodiment and the crosslinkability described later. It can be appropriately selected and used according to the type of liquid crystal material. In particular, in this embodiment, it is preferable that the coumarin is bonded to oxygen at the 7th or 6th position. This is because such a photoreactive group I has high photoreactivity.

The photoreactive group I used in this embodiment is preferably ^{one in} which the above A ¹ is 1,4-phenylene which is unsubstituted or optionally substituted with fluorine, chlorine, cyano, alkyl or alkoxy. By the A ¹ has such a structure, the molecular structure of photoreactive compound used in the present embodiment, since it in an approximation by the molecular structure described below crosslinked liquid crystal material, and the photoreactive compound This is because the compatibility with the crosslinkable liquid crystal material can be further improved, and as a result, a retardation film having a smaller haze can be produced.

  Examples of such photoreactive group I include those represented by the following formulas (I) -1 and (I) -2.

Here, in the above formula, R ⁴ represents hydrogen, alkyl having 1 to 4 carbon atoms, or alkoxy having 1 to 4 carbon atoms.
R ⁵ and R ⁶ each independently represent hydrogen, alkyl having 1 to 4 carbon atoms, alkoxy having 1 to 4 carbon atoms, cyano, or alkyloxycarbonyl having 2 to 6 carbon atoms.

In this embodiment, any one of the photoreactive groups I represented by the above formulas (I) -1 and (I) -2 can be suitably used. In particular, in this embodiment, A compound in which R ⁴ in the above formulas (I) -1 and (I) -2 is hydrogen or a methyl group and R ⁵ is hydrogen can be used more suitably. This is because the photoreactive group I having such a structure has high photoreactivity.

  Specific examples of such photoreactive group I include, for example, those represented by the following formula.

On the other hand, the photoreactive group II is not particularly limited as long as it has a structure represented by the above formula (II), and the use of the retardation film produced according to this embodiment, which will be described later. It can be appropriately selected and used according to the type of the crosslinkable liquid crystal material. Among these, in this embodiment, the above A ² and A ³ are each independently 1,4-phenylene, which is unsubstituted or optionally substituted with fluorine, chlorine, cyano, alkyl, alkoxy, or alkyloxycarbonyl, 4, What is 4′-biphenylene or 2,6-naphthylene can be preferably used. Since A ² and A ³ have such a structure, the molecular structure of the photoreactive compound used in this embodiment can be approximated by the molecular structure of the crosslinkable liquid crystal material described later. This is because the compatibility between the functional compound and the crosslinkable liquid crystal material can be further improved, and as a result, a retardation film having a smaller haze can be produced.

  As such a photoreactive group II, what is represented by following formula (II) -1, (II) -2, and (II) -3 can be illustrated, for example.

Here, in the above formula, R ⁷ represents hydrogen, unsubstituted or optionally substituted alkyl having 1 to 20 carbon atoms substituted with fluorine or chlorine.
R ⁸ and R ⁹ each independently represent hydrogen or alkoxy having 1 to 4 carbon atoms. R ¹⁰ represents hydrogen, alkyl having 1 to 4 carbons, alkoxy having 1 to 4 carbons, alkyloxycarbonyl having 2 to 6 carbons, or cyano.
Further, m is 0 or 1.

  Specific examples of the photoreactive group II used in this embodiment include those represented by the following formulas.

  The photoreactive compound used in this embodiment may have only one photoreactive group or may have a plurality of photoreactive groups. Among these, in this embodiment, it is preferable to use a photoreactive compound having a plurality of photoreactive groups. This is because by using such a photoreactive compound, it becomes easy to impart orientation to the phase difference layer forming layer in the above-described orientation imparting step.

  When a compound having a plurality of photoreactive groups represented by the above formula (I) or (II) in the molecule is used as the photoreactive compound, the photoreactive compound is represented by the same formula. May contain a plurality of the same photoreactive groups, may be represented by the same formula, may contain a plurality of photoreactive groups having different structures, and may be represented by different formulas. It may be an embodiment containing a plurality of photoreactive groups.

  Moreover, the photoreactive compound used in this embodiment may exhibit liquid crystallinity or may not exhibit liquid crystallinity.

  Examples of the photoreactive compound used in this embodiment include polymers of compounds represented by low molecular compounds (III) -1 to (III) -5 and (III) -1 represented by the following formulae: Can be mentioned.

In the above formula, W ¹ represents the photoreactive group. R ¹¹ represents hydrogen or methyl. Furthermore, n represents an integer of 0 to 20, and p represents 0 or 1.

Here, in the case of the polymer of the compound represented by the formula (III) -1, either a homopolymer or a copolymer may be used.
Further, in the case of a copolymer, a copolymer with a monomer other than the compound represented by (III) -1 may be used as long as the compatibility with a crosslinkable liquid crystal material described later is not impaired.
Further, in the case of a copolymer with a monomer other than the compound represented by (III) -1, the monomer other than the compound represented by (III) -1 may be either a liquid crystalline monomer or a non-liquid crystalline monomer. A liquid crystal monomer is preferable because compatibility with a crosslinkable liquid crystal material can be improved.

  In this embodiment, any of the photoreactive compound represented by the above formulas (III) -1 to (III) -5 and the polymer of the compound represented by (III) -1 is preferably used. Among them, polymers containing units represented by the following formulas (IV) -1 to (IV) -3 are preferably used.

Here, in the above formula, R ¹² represents hydrogen or a methyl group. R ¹³ represents hydrogen, alkyl having 1 to 4 carbons, or alkoxy having 1 to 4 carbons. R ¹⁴ and R ¹⁵ each independently represent hydrogen, alkyl having 1 to 4 carbon atoms, alkoxy having 1 to 4 carbon atoms, alkyloxycarbonyl having 2 to 6 carbon atoms, or cyano. R ¹⁶ represents unsubstituted or optionally substituted alkyl having 1 to 20 carbon atoms substituted with fluorine or chlorine. R <^17> , R < ¹⁸ > represents hydrogen and a C1-C4 alkoxy each independently. q represents an integer of 2 to 20.

  Specific examples of the photoreactive compound used in this embodiment include the following compounds.

(Photoreactive compound having a photoreactive group represented by the above formula (I))
7-{[4- (4-acryloyloxy) butoxy] benzoyloxy} coumarin, 7-{[4- (6-acryloyloxy) hexyloxy] benzoyloxy} coumarin, 4-methyl-7-{[4- (4 -Acryloyloxy) butyroxy] benzoyloxy} coumarin, 4-methyl-7-{[4- (6-acryloyloxy) hexyloxy] benzoyloxy} coumarin, 6-{[4- (6-acryloyloxy) hexyloxy] benzoyloxy } Coumarin, 4-methyl-6-{[4- (6-acryloyloxy) hexyloxy] benzoyloxy} coumarin, poly [7-{[4- (6-acryloyloxy) hexyloxy] benzoyloxy} coumarin], poly [ 7-{[4- (8-acryloyloxy) octyloxy] benzoyloxy} coumarin], poly [4-methyl-7-{[4- ( -Acryloyloxy) hexyloxy] benzoyloxy} coumarin], poly [4-methyl-7-{[4- (8-acryloyloxy) octyloxy] benzoyloxy} coumarin], poly [7-{[4- (6-methacryloyl) Oxy) hexyloxy] benzoyloxy} coumarin], poly [7-{[4- (8-methacryloyloxy) octyloxy] benzoyloxy} coumarin], poly [7-{[4- (11-methacryloyloxy) undecyloxy] benzoyloxy } Coumarin], poly [4-methyl-7-{[4- (6-methacryloyloxy) hexyloxy] benzoyloxy} coumarin], poly [4-methyl-7-{[4- (8-methacryloyloxy) octyloxy] Benzoyloxy} coumarin], poly [4-methyl-7-{[4- (11-methacryloyloxy) undecyloxy] benzoyl Xy} coumarin], poly [4-methyl-6-{[4- (6-methacryloyloxy) hexyloxy] benzoyloxy} coumarin], poly [4-methyl-6-{[4- (8-methacryloyloxy) octyloxy ] Benzoyloxy} coumarin], poly [4-methyl-6-{[4- (11-methacryloyloxy) undecyloxy] benzoyloxy} coumarin].

(Photoreactive compound having a photoreactive group represented by the formula (II))
1- [4- [4- [4-[(E) -2-methoxycarbonylvinyl] phenoxycarbonyl] phenoxy] butyloxycarbonyl] ethylene, 1- [6- [4- [4-[(E) -2] -Methoxycarbonylvinyl] phenoxycarbonyl] phenoxy] hexyloxycarbonyl] ethylene, 1- [4- [4- [2-methoxy-4-[(E) -2-methoxycarbonylvinyl] phenoxycarbonyl] phenoxy] butyloxycarbonyl ] Ethylene, 1- [6- [4- [2-methoxy-4-[(E) -2-methoxycarbonylvinyl] phenoxycarbonyl] phenoxy] hexyloxycarbonyl] ethylene, poly [1- [6- [4- [4-[(E) -2-methoxycarbonylvinyl] phenoxycarbonyl] phenoxy] hexyloxy Carbonyl] ethylene], poly [1- [8- [4- [4-[(E) -2-methoxycarbonylvinyl] phenoxycarbonyl] phenoxy] octyloxycarbonyl] ethylene], poly [1- [11- [4 -[4-[(E) -2-methoxycarbonylvinyl] phenoxycarbonyl] phenoxy] undecyloxycarbonyl] ethylene], poly [1- [6- [4- [2-methoxy-4-[(E)- 2-methoxycarbonylvinyl] phenoxycarbonyl] phenoxy] hexyloxycarbonyl] ethylene], poly [1- [8- [4- [2-methoxy-4-[(E) -2-methoxycarbonylvinyl] phenoxycarbonyl] phenoxy ] Octyloxycarbonyl] ethylene], poly [1- [11- [4- [2-methoxy-4-[( ) -2-Methoxycarbonylvinyl] phenoxycarbonyl] phenoxy] undecyloxycarbonyl] ethylene], poly [1- [6- [4- [4-[(E) -2-methoxycarbonylvinyl] phenoxycarbonyl] phenoxy] Hexyloxycarbonyl] -1-methylethylene], poly [1- [8- [4- [4-[(E) -2-methoxycarbonylvinyl] phenoxycarbonyl] phenoxy] octyloxycarbonyl] -1-methylethylene] Poly [1- [11- [4- [4-[(E) -2-methoxycarbonylvinyl] phenoxycarbonyl] phenoxy] undecyloxycarbonyl] -1-methylethylene], poly [1- [6- [ 4- [4-[(E) -2-ethoxycarbonylvinyl] phenoxycarbonyl] phenoxy Si] hexyloxycarbonyl] -1-methylethylene], poly [1- [8- [4- [4-[(E) -2-propoxycarbonylvinyl] phenoxycarbonyl] phenoxy] octyloxycarbonyl] -1-methyl Ethylene], poly [1- [6- [4- [2-methoxy-4-[(E) -2-methoxycarbonylvinyl] phenoxycarbonyl] phenoxy] hexyloxycarbonyl] -1-methylethylene], poly [1 -[8- [4- [2-methoxy-4-[(E) -2-methoxycarbonylvinyl] phenoxycarbonyl] phenoxy] octyloxycarbonyl] -1-methylethylene], poly [1- [11- [4 -[2-methoxy-4-[(E) -2-methoxycarbonylvinyl] phenoxycarbonyl] phenoxy] undec Oxycarbonyl] -1-methylethylene], poly [1- [6- [4- [2-methoxy-4-[(E) -2-ethoxycarbonylvinyl] phenoxycarbonyl] phenoxy] hexyloxycarbonyl] -1- Methylethylene], poly [1- [8- [4- [2-methoxy-4-[(E) -2-propoxycarbonylvinyl] phenoxycarbonyl] phenoxy] octyloxycarbonyl] -1-methylethylene], poly [ 1- [6- [4- [4-[(E) -2-methoxycarbonylvinyl] phenoxycarbonyl] naphthalin-6-yloxy] hexyloxycarbonyl] -1-methylethylene], poly- [1- [11- [5- [4-[(E) -2-methoxycarbonylvinyl] benzoyloxy] -2- [6- [2-methoxy- (E) -4- (Methoxycarbonylvinyl) phenoxy] oxyhexyl] benzoyloxy] undecyloxycarbonyl] -1-methylethylene], poly- [1- [11- [5- [4-[(E) -2-methoxycarbonylvinyl] benzoyloxy ] -2- (4-Propylbenzoyloxy) benzoyloxy] undecyloxycarbonyl] -1-methylethylene], poly- [1- [11- [5- [4-[(E) -2-methoxycarbonylvinyl]] Benzoyloxy] -2- (4-pentylbenzoyloxy) benzoyloxy] undecyloxycarbonyl] -1-methylethylene], poly- [1- [8- [5- [4-[(E) -2-methoxycarbonyl] Vinyl] benzoyloxy] -2- (4-propylbenzoyloxy) benzoyloxy] octyloxycarbonyl] -1-methylethyl ]

  In this embodiment, only one kind of such a photoreactive compound may be used, or a plurality of kinds of photoreactive compounds may be mixed and used.

b) Crosslinkable liquid crystal material Next, the crosslinkable liquid crystal material used in the ultraviolet curable composition will be described. The crosslinkable liquid crystal material used in this embodiment has a crosslinkable functional group.

  The crosslinkable liquid crystal material used in this embodiment is not particularly limited as long as it can give a desired retardation to the retardation film produced according to this embodiment, and includes a compound having any liquid crystallinity. Can be used. Especially, in this aspect, what shows a nematic phase as said crosslinkable liquid crystal material can be used conveniently. This is because nematic liquid crystals are easily arranged regularly as compared with liquid crystal materials exhibiting other liquid crystal phases.

The crosslinkable functional group of the crosslinkable liquid crystal material used in this embodiment is not particularly limited as long as it can form intermolecular crosslinks. Examples of such a crosslinkable functional group include a radiation crosslinkable functional group that forms a crosslink by radiation such as ultraviolet rays and electron beams, and a heat crosslinkable functional group that forms a crosslink by the action of heat. Among these, in the present embodiment, the radiation crosslinkable functional group is preferable, and an ultraviolet crosslinkable functional group that forms a crosslink by irradiation with ultraviolet rays is particularly preferable. The reason is as follows.
That is, when the thermally crosslinkable functional group is used as the crosslinkable liquid crystal material, for example, when the retardation layer forming layer is formed by applying and drying the ultraviolet curable composition in this step, the drying is performed. Sometimes the crosslinkable liquid crystal material is cross-linked, and as a result, the retardation of the retardation film formed may not be within a desired range. However, this is because there are few such problems with the ultraviolet crosslinkable functional group. Moreover, it is because the process of bridge | crosslinking the said crosslinkable liquid crystal material can be completed in a short time by using an ultraviolet crosslinkable functional group.

  The UV crosslinkable functional group is usually a polymerizable functional group capable of forming a crosslink by irradiating ultraviolet rays and obtaining a polymer compound of the crosslinkable liquid crystal material, or crosslinked by irradiating ultraviolet rays. A dimerization functional group that can form a dimer of the crosslinkable liquid crystal material is used.

  Examples of the polymerizable functional group include acryloyl group, methacryloyl group, vinyl ether group, oxetanyl group, glycidyl group, and alicyclic epoxy group.

  Examples of the dimerization functional group include cinnamate, coumarin, chalcone, benzylidenephthalimidine, benzylideneacetophenone, diphenylacetylene, stilbazole, uracil, quinolinone, thymine, maleimide, cinnamylideneacetic acid and derivatives thereof. it can.

  In this embodiment, any of the polymerizable functional group and the dimerized functional group can be preferably used, and among them, the polymerizable functional group is preferably used. This is because the polymerizable functional group has a high reaction rate when a photopolymerization initiator is added, and a highly durable layer can be formed with a smaller amount of UV irradiation than the dimerized functional group.

  In this embodiment, it is preferable to use an acryloyl group or an oxetanyl group among the polymerizable functional groups. This is because these polymerizable functional groups are excellent in reactivity. Furthermore, in this embodiment, it is preferable to use an acryloyl group among these polymerizable functional groups. This is because the crosslinkable liquid crystal material having an acryloyl group is easy to apply to this embodiment because there are many types that are industrially available.

  The crosslinkable liquid crystal material used in this embodiment may have a plurality of the crosslinkable functional groups or may have only one. In this embodiment, a crosslinkable liquid crystal material having a plurality of crosslinkable functional groups and a crosslinkable liquid crystal material having only one crosslinkable functional group may be mixed and used.

The crosslinkable liquid crystal material used in this embodiment preferably includes at least a structure represented by —A ⁴ —CO—O—A ⁵ —. This is because the compatibility of the crosslinkable liquid crystal material with the photoreactive compound can be improved by including the above structure.

Here, the above A ⁴ and A ⁵ are each independently 1,4-phenylene or 4,4′-biphenylene which is unsubstituted or optionally substituted with fluorine, chlorine, cyano, alkyl, alkoxy, or alkyloxycarbonyl. 1,4-naphthylene, 2,6-naphthylene, pyridine-2,5-diyl, pyrimidine-2,5-diyl, 1,3-dioxane-2,5-diyl, piperidine-1,4-diyl, or Represents piperazine-1,4-diyl.

  Among the crosslinkable liquid crystal materials having such a structure, examples of those having a plurality of the crosslinkable functional groups include compounds represented by the following formulas (1) to (7).

  Examples of the crosslinkable liquid crystal material having such a structure include those represented by the following formulas (8) and (9) as those having only one crosslinkable functional group.

Here, in the above formulas (1) to (9), L ¹ and L ² each independently represent —O— or —O—CO—O—. B represents a mesogenic group represented by the following formulas (i) to (viii).

R ¹⁹ each independently represents hydrogen or a methyl group. d to l are each independently an integer of 2 to 12, more preferably 4 to 10.
Further, L ³ and L ⁴ each independently represent any of the following formulas (ix) to (xiii).

Moreover, r represents the integer of 0-20. R ²¹ represents hydrogen, chlorine, bromine, iodine, an alkyl group having 1 to 10 carbon atoms, an alkyloxycarbonyl group, an alkoxy group, a cyano group, or a nitro group.

  In addition to the above, specific examples of the crosslinkable liquid crystal material used in this embodiment include, for example, JP-A-4-227684, JP-A-9-111240, JP-A-10-182556, and JP-A-11-513019. No. 2000-98113, No. 2002-69450, No. 2002-30042, No. 2003-96066, and No. 2004-123597. Can be mentioned.

  The crosslinkable liquid crystal material used in this embodiment may be one type or a mixture of two or more types.

c) UV curable composition The UV curable composition used in this step contains the photoreactive compound and the crosslinkable liquid crystal material, but the light contained in the UV curable composition. The ratio of the reactive compound and the crosslinkable liquid crystal material is not particularly limited as long as the retardation film produced according to this embodiment can provide a predetermined retardation, and is produced according to this embodiment. It can determine suitably according to the use etc. of the retardation film made. Especially in this aspect, it is preferable that content of the said photoreactive compound with respect to 100 mass parts of said crosslinkable liquid crystal materials exists in the range of 0.1 mass part-60 mass parts, especially 3 mass parts- It is preferably within the range of 50 parts by mass, and particularly preferably within the range of 10 parts by mass to 50 parts by mass. If the content of the photoreactive compound is less than the above range, for example, it may be difficult to regularly arrange the crosslinkable liquid crystal material in the retardation film produced according to this embodiment. is there. Moreover, it is because there exists a possibility that desired retardation property cannot be provided to the retardation film manufactured by this aspect when it is more than the said range.

  Although the ultraviolet curable composition used for this process contains the said photoreactive compound and the said crosslinkable liquid crystal material, it may contain other structures other than these as needed. . Examples of such other configurations include solvents, photopolymerization initiators, polymerization inhibitors, plasticizers, surfactants, and silane coupling agents. Especially in this aspect, it is preferable to use a photoinitiator and a solvent as said other structure. This is because by containing a photopolymerization initiator in the ultraviolet curable composition, it is possible to accelerate the cross-linking formation reaction of the cross-linkable liquid crystal material in the liquid crystal cross-linking step described later. In addition, when the ultraviolet curable composition contains a solvent, for example, even when an ultraviolet curable composition containing a crosslinkable liquid crystal material or a photoreactive compound having a high melting point or softening point is used, It is because it becomes easy to apply at room temperature.

  The solvent is not particularly limited as long as it can dissolve the photoreactive compound and the crosslinkable liquid crystal material at a desired concentration. Examples of such solvents include ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone and cyclopentanone; hydrocarbon solvents such as benzene, toluene and hexane; ethers such as tetrahydrofuran and 1,2-dimethoxyethane. Solvents; alkyl halide solvents such as chloroform and dichloromethane; ester solvents such as methyl acetate, ethyl acetate, propyl acetate, butyl acetate and propylene glycol monomethyl ether acetate; amide solvents such as N, N-dimethylformamide; and dimethyl Examples thereof include, but are not limited to, sulfoxide solvents such as sulfoxide.

  Further, the solvent used in this embodiment may be one type or a mixed solvent of two or more types of solvents.

  As said photoinitiator, it can select and use suitably according to the kind etc. of the polymerizable functional group which the said crosslinkable liquid crystal material has. Among these, in this embodiment, when a crosslinkable liquid crystal material having an acryloyl group and a methacryloyl group is used as the polymerizable functional group, it is preferable to use a radical photopolymerization initiator, while the polymerizable functional group In the case of using a crosslinkable liquid crystal material having a vinyl ether group, an oxetanyl group, a glycidyl group, and an alicyclic epoxy group, it is preferable to use a photocationic polymerization initiator.

  Examples of the photo radical polymerization initiator include benzyl, benzoin isobutyl ether, benzoin isopropyl ether, benzophenone, benzoyl benzoic acid, methyl benzoyl benzoate, 4-benzoyl-4′-methyldiphenyl sulfide, benzyl methyl ketal, dimethylaminomethyl. Benzoate, 2-n-butoxyethyl-4-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, 3,3′-dimethyl-dimethyl-4-methoxybenzophenone, methylobenzoylformate, 2-methyl-1- ( 4- (methylthio) phenyl) -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 1-hydroxycyclohexyl Erniketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 2-chlorothioxanthone, 2,4- Diethylthioxanthone, 2,4-diisopropylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 1-chloro-4-proxythioxanthone, 2-hydroxy-2-methyl- [4- (1-methylvinyl) phenyl] propanol oligomer Etc.

  Examples of the cationic photopolymerization initiator include sulfonic acid esters, imide sulfonates, dialkyl-4-hydroxysulfonium salts, arylsulfonic acid-p-nitrobenzyl esters, silanol-aluminum complexes, (η6-benzene) (η5-cyclo Pentadienyl) iron (II) and the like. More specifically, benzoin tosylate, 2,5-dinitrobenzyl tosylate, N-tosicphthalimide and the like can be mentioned.

  Furthermore, examples of the compound that can be used as the photo radical polymerization initiator and the photo cation polymerization initiator include aromatic iodonium salts, aromatic sulfonium salts, aromatic diazonium salts, aromatic phosphonium salts, triazine compounds, An iron arene complex etc. can be illustrated. More specifically, chlorides with or without iodine such as diphenyliodonium, ditolyliodonium, bis (p-tert-butylphenyl) iodonium, bis (p-chlorophenyl) iodonium; bromide, borofluoride, hexafluorophosphate salt, Iodonium salts such as hexafluoroantimonate salts, chlorides of sulfonium such as triphenylsulfonium, 4-tert-butyltriphenylsulfonium, tris (4-methylphenyl) sulfonium, bromides, borofluorides, hexafluorophosphate salts, hexafluoro Sulfonium salts such as antimonate salts, 2,4,6-tris (trichloromethyl) -1,3,5-triazine, 2-phenyl-4,6-bis (trichloromethyl) -1,3,5-triazine, 2 − And the like Chiru 4,6-bis (trichloromethyl) -1,3,5-2,4,6-substituted-1,3,5-triazine compounds such as triazines.

  Moreover, when using the said photoinitiator, a photoinitiator adjuvant can be used together. Examples of such photopolymerization initiation assistants include tertiary amines such as triethanolamine and methyldiethanolamine, and benzoic acid derivatives such as ethyl 2-dimethylaminoethylbenzoate and ethyl 4-dimethylamidebenzoate. Yes, but not limited to these.

  The amount of the photopolymerization initiator contained in the ultraviolet curable composition is 0.01% by mass to 20% by mass with respect to the mass of the crosslinkable liquid crystal material contained in the ultraviolet curable composition. It is preferably within the range, and in particular, it is preferably within the range of 0.1% by mass to 10% by mass, and particularly preferably within the range of 0.3% by mass to 5% by mass. If the addition amount of the photopolymerization initiator is less than the above range, the amount of ultraviolet irradiation necessary to crosslink the crosslinkable liquid crystal material may increase too much. It is because there exists a possibility of inhibiting the reaction of a photoreactive compound.

  In addition, when the said ultraviolet curable composition contains the said solvent, it is not specifically limited as solid content concentration of the said ultraviolet curable composition, The said ultraviolet curable composition in this process, The concentration can be set arbitrarily according to the coating method applied on the transparent substrate.

(2) Transparent substrate Next, the transparent substrate used for this process is demonstrated. The transparent substrate used in this step has transparency, and supports the retardation layer in the retardation film produced according to this embodiment.

The transparency of the transparent substrate used in this step may be arbitrarily determined according to the transparency required for the retardation film produced according to this embodiment, but the transmittance in the visible light region is usually 80% or more. It is preferably 90% or more. When the transmittance is in the above range, for example, when the retardation film produced according to this embodiment is used as a viewing angle compensation film for a liquid crystal display device, the display luminance of the liquid crystal display device is prevented from being lowered. Because you can.
Here, the transmittance of the transparent substrate can be measured according to JIS K7361-1 (Testing method for total light transmittance of plastic transparent material).

  The transparent substrate used in this step may be a flexible material having flexibility or a rigid material having no flexibility such as a glass substrate as long as it has the above transparency. Especially, it is preferable to use a flexible material in this process. By using a flexible material, this step can be performed in a roll-to-roll process (a retardation layer forming layer is continuously formed on a transparent substrate unwound from a rolled-up transparent substrate, and then rolled again. This is because the retardation film can be produced with high productivity according to this embodiment.

Further, the transparent substrate used in this step may be an optically isotropic substrate or a substrate having retardation.
Here, the optically isotropic substrate means a transparent substrate having Re of 10 nm or less and Rth of 40 nm or less. In particular, the optically isotropic substrate used in this step preferably has Re of 5 nm or less. Rth is preferably 20 nm or less.

The above Re and Rth are defined by the following formulas.
Re = (nx−ny) × d
Rth = [{(nx + ny) / 2} -nz] × d
In the formula, nx is the refractive index in the direction with the highest refractive index in the in-plane direction of the transparent substrate, ny is the refractive index in the direction with the lowest refractive index in the in-plane direction of the transparent substrate, and nz is the thickness direction of the transparent substrate. Is the refractive index. D is the thickness of the transparent substrate.

  Examples of the material constituting the optically isotropic substrate include cellulose derivatives, norbornene polymers, cycloolefin polymers, polycarbonates, polyesters, and the like. Among these, the optically isotropic substrate used in this step is preferably a cellulose derivative or a cycloolefin polymer. This is because the cellulose derivative is particularly excellent in optical isotropy. Moreover, it is because a cycloolefin type polymer is excellent in durability.

  As said cellulose derivative, it is preferable to use a cellulose ester, Furthermore, it is preferable to use cellulose acylates among cellulose esters. This is because cellulose acylates are advantageous in terms of availability because they are widely used industrially.

  Moreover, as said cellulose acylates, C2-C4 lower fatty acid ester is preferable. Such a lower fatty acid ester may contain only a single lower fatty acid ester, for example, cellulose acetate, and a plurality of fatty acid esters such as cellulose acetate butyrate and cellulose acetate propionate may be used. It may be included.

In this step, cellulose acetate can be particularly preferably used among the above lower fatty acid esters. Moreover, as a cellulose acetate, it is most preferable to use the triacetyl cellulose whose average acetylation degree is 57.5-62.5% (substitution degree: 2.6-3.0).
Here, the degree of acetylation means the amount of bound acetic acid per unit mass of cellulose. The degree of acetylation can be determined by measurement and calculation of the degree of acetylation in ASTM: D-817-91 (test method for cellulose acetate and the like). In addition, the acetylation degree of the triacetyl cellulose which comprises a triacetyl cellulose film can be calculated | required by said method, after removing impurities, such as a plasticizer contained in a film.

  On the other hand, the cycloolefin polymer is a polymer having a monomer unit composed of a cyclic olefin (cycloolefin) such as norbornene or a polycyclic norbornene monomer. Such a cycloolefin-based polymer can control the glass transition point and water absorption rate within a preferable range by molecular design, and can satisfy good heat resistance and appropriate water absorption.

The cycloolefin polymer used in this step preferably has a saturated water absorption at 23 ° C. of 1% by mass or less. This is because a transparent substrate made of such a cycloolefin-based polymer is less likely to cause changes in optical properties and dimensional changes due to water absorption.
Here, the said saturated water absorption shall mean the value obtained by immersing in 23 degreeC water for 1 week, and measuring an increase weight based on ASTMD570.

  Moreover, as for the cycloolefin type polymer used for this process, that whose glass transition temperature is in the range of 100 to 200 degreeC is preferable. This is because a transparent substrate made of such a cycloolefin polymer is excellent in heat resistance and processability.

  Examples of the transparent substrate made of a cycloolefin polymer used in this step include “Topas” sold by Ticona, Germany, “Arton” sold by JSR, and ZEON Corporation. “ZEONOR” and “ZEONEX” sold by the company, “Apel” sold by Mitsui Chemicals, Inc., and the like.

In addition, the structure of the transparent substrate used for this process is not restricted to the structure which consists of a single layer, You may have the structure by which the several layer was laminated | stacked.
Here, in the case of a configuration in which a plurality of layers are laminated, layers having the same composition may be laminated, or a plurality of layers having different compositions may be laminated. May be.

  As a transparent substrate having a structure in which the plurality of layers are laminated, an ultraviolet ray and / or an electron beam curable resin is formed on a layer composed of the cellulose derivative, norbornene polymer, cycloolefin polymer, polycarbonate, polyester, or the like. A laminate of layers cured by ultraviolet rays or electron beams can be mentioned. The layer in which the ultraviolet ray and / or electron beam curable resin is cured by ultraviolet ray or electron beam serves as a shielding layer for suppressing the additive contained in the layer composed of the polymer from moving to the retardation layer, It plays the role which improves the adhesiveness of the layer comprised from the said polymer, and retardation layer.

  The ultraviolet curable resin and the electron beam curable resin have two or more polymerizable groups such as a polymerizable vinyl group, allyl group, (meth) acryloyl group, isophenyl group, epoxy group, and oxetanyl group. Or what forms a crosslinked structure or network structure by irradiation of an electron beam is preferable. Among these, in this step, a (meth) acryloyl group or an epoxy group is preferable from the viewpoint of polymerization rate and reactivity, and a polyfunctional monomer or oligomer is preferable. Examples of such ultraviolet curable resins and electron beam curable resins include ultraviolet curable polyol acrylates, epoxy acrylates, urethane acrylates, polyester acrylates, and epoxy resins. These are usually used together with known photopolymerization initiators. The photopolymerization initiator or photosensitizer contained in the ultraviolet and / or electron beam curable resin composition excluding the solvent component that volatilizes after coating and drying is 0.5% by mass to 5% by mass of the composition. Is preferred.

When a substrate having retardation is used as the transparent substrate, the transparent substrate is not particularly limited as long as it can impart a desired refractive index anisotropy to the retardation film produced according to this embodiment. In particular, in this step, it is preferable to use a transparent substrate having properties as a λ / 4 plate or properties as a λ / 2 plate.
Here, the above-mentioned “having properties as a λ / 4 plate” usually means that Re of the transparent substrate shows a value of ¼ of the wavelength of incident light. As the transparent substrate to be used, those having Re at a wavelength of 550 nm in the range of 120 nm to 150 nm are preferable.
In addition, the above-mentioned “having properties as a λ / 2 plate” usually means that Re of the transparent substrate shows a value half of the wavelength of incident light. The transparent substrate to be used is preferably one having Re at a wavelength of 550 nm in the range of 250 nm to 300 nm.

  The thickness of the transparent substrate used in this step is not particularly limited as long as it is within a range in which necessary self-supporting properties can be provided according to the use of the retardation film produced according to this embodiment. In particular, in this step, it is preferably in the range of 25 μm to 1000 μm, particularly preferably in the range of 30 μm to 100 μm. This is because if the thickness of the transparent substrate is thinner than the above range, the necessary self-supporting property may not be imparted to the retardation film produced according to this embodiment. Further, if the thickness is thicker than the above range, for example, when cutting the retardation film produced according to this embodiment, the processing waste may increase or the cutting blade may be worn quickly. It is.

(3) Method for forming retardation layer forming layer In this step, the ultraviolet curable composition is coated on the transparent substrate to form the retardation layer forming layer. As a coating method for coating the curable composition on the transparent substrate, any method can be used as long as it can form a retardation layer forming layer having desired flatness according to the composition of the ultraviolet curable composition. It is not particularly limited. Examples of such coating methods include gravure coating, reverse coating, knife coating, dip coating, spray coating, air knife coating, roll coating, printing, curtain coating, die coating, and casting. Examples thereof include a method, a bar coating method, an extrusion coating method, and an E-type coating method.

  Moreover, the thickness of the coating film of the ultraviolet curable composition exhibits a desired retardation according to the present embodiment depending on the type of the crosslinkable liquid crystal material contained in the ultraviolet curable composition used in this step. The retardation film is not particularly limited as long as it is within a range capable of producing a retardation film. In particular, in this step, it is preferably within a range of 0.1 μm to 50 μm, particularly preferably within a range of 0.5 μm to 30 μm, and in particular within a range of 0.5 μm to 10 μm. Is preferred.

  In addition, when a solvent-containing material is used as the ultraviolet curable composition, the drying method for the coating film may be a commonly used drying method such as a heat drying method, a vacuum drying method, a gap drying method, or the like. Can be used. In addition, the drying method in the present invention is not limited to a single method, and for example, a plurality of drying methods may be adopted in such a manner that the drying method is sequentially changed according to the amount of the remaining solvent.

  In addition, when using the said heat drying method in this process, it is preferable to dry at the temperature below the crystal-liquid crystal phase transition temperature of the crosslinkable liquid crystal material contained in the said ultraviolet curable composition.

4). Liquid Crystal Crosslinking Step Next, the liquid crystal crosslinking step used in this embodiment will be described. This step is a step of crosslinking the crosslinkable liquid crystal material arranged in the liquid crystal alignment step.

  In this step, the method for crosslinking the crosslinkable liquid crystal material is not particularly limited as long as it is a method capable of causing a crosslinking formation reaction of the crosslinkable functional group of the crosslinkable liquid crystal material. A method corresponding to the type of the crosslinkable functional group possessed by the crosslinkable liquid crystal material can be appropriately selected and used. As such a method, for example, when a crosslinkable liquid crystal material having an ultraviolet polymerizable functional group is used, an ultraviolet ray having a wavelength capable of causing a polymerization reaction of the ultraviolet polymerizable functional group is used. A method of irradiating the retardation layer forming layer is used. When such a method of irradiating ultraviolet rays is used, non-polarized ultraviolet rays are usually used from the viewpoint that the ultraviolet rays for reacting the crosslinkable liquid crystal material have high reactivity.

5. Retardation film A retardation film produced by the method for producing a retardation film of this embodiment is formed on the transparent substrate, the cross-linked product of the cross-linkable liquid crystal material, and the reaction of the photoreactive compound. And a retardation layer containing a product.

  The cross-linked product of the cross-linkable liquid crystal material is present in a regularly arranged state by the action of the reaction product of the photoreactive compound. The arrangement is not particularly limited as long as the optical function can be expressed. Examples of such an arrangement state include a state in which the mesogens are parallel to the transparent substrate and the average orientation direction is oriented in a specific direction in the plane. This liquid crystal structure is called a homogeneous alignment structure, and by having such a structure, the optical function film of the present invention can be optically imparted with properties as an A plate. Furthermore, the mesogen can be oriented in a direction inclined with respect to the transparent substrate, and the inclination angle dependency in a specific direction of the retardation layer can be asymmetric with respect to the normal direction.

  In addition, since the retardation film of the present invention does not require an alignment layer, as described above, the three-dimensional liquid crystal material that has been difficult to realize with a retardation film that requires a conventional alignment layer. Orientation can be realized.

  Such a retardation film can be used, for example, as an optical compensation film (for example, a viewing angle compensation film) used in a liquid crystal display device, an elliptically polarizing plate, a circularly polarizing plate, and a brightness enhancement plate.

B. Manufacturing method of retardation film of second aspect Next, a manufacturing method of the retardation film of the second aspect will be described. The method for producing a retardation film according to this aspect includes a liquid crystalline structural unit having liquid crystallinity in a molecule and a photoreactive polymer liquid crystal having a photoreactive group as the retardation layer forming coating liquid. Is an embodiment using
That is, the method for producing a retardation film of this embodiment uses a transparent substrate, and contains a liquid crystalline structural unit having liquid crystallinity in the molecule and a photoreactive polymer liquid crystal having a photoreactive group on the transparent substrate. By applying a polymer liquid crystal-containing composition, a retardation layer forming layer forming step for forming a retardation layer forming layer on the transparent substrate, and polarized ultraviolet rays from one side are applied to the retardation layer forming layer. Irradiation and reacting the photoreactive group to cause the retardation layer forming layer to exhibit orientation with respect to the liquid crystalline structural unit, and the polarizing UV of the retardation layer forming layer The retardation layer is formed so that the surface of the irradiated surface reaches the glass phase-liquid crystal phase transition temperature of the photoreactive polymer liquid crystal before the surface opposite to the surface irradiated with the polarized ultraviolet light. By heating the working layer, A liquid crystal alignment step of arranging the serial liquid crystalline structural units, is characterized in that it has a.

  Such a method for producing a retardation film of this aspect will be described with reference to the drawings. FIG. 2 is a schematic view showing an example of a method for producing the retardation film of this embodiment. As illustrated in FIG. 2, the method for producing a retardation film of this embodiment uses a transparent substrate 1 (FIG. 2A), and on the transparent substrate 1, a liquid crystalline structural unit having liquid crystallinity in the molecule. And forming a retardation layer forming layer 2B ′ on the transparent substrate 1 by coating a polymer liquid crystal-containing composition containing a photoreactive polymer liquid crystal having a photoreactive group The layer forming step (FIG. 2B) and the retardation layer forming layer 2B ′ are irradiated with polarized ultraviolet rays from the side opposite to the transparent substrate 1 (A), and the photoreactive group is irradiated. An orientation imparting step (FIG. 2 (c)) for causing the retardation layer forming layer 2B ′ to exhibit orientation with respect to the liquid crystalline structural unit by reacting with the transparent layer forming layer 2B ′. The surface (A) on the side opposite to the substrate 1 is ahead of the surface (B) on the transparent substrate 1 side. A liquid crystal alignment step of aligning the liquid crystalline structural units by heating the retardation layer forming layer 2B ′ so as to reach the glass phase-liquid crystal phase transition temperature of the photoreactive polymer liquid crystal (FIG. 2 ( and d)) to produce a retardation film 10B having a transparent substrate 1 and a retardation layer 2B directly formed on the transparent substrate 1 (FIG. 2 (e)).

  According to this aspect, the orientation imparting step imparts the orientation to the retardation layer forming layer by irradiating the retardation layer forming layer with polarized ultraviolet light from one side, and In the liquid crystal alignment step, the surface of the retardation layer forming layer irradiated with the polarized ultraviolet light has a surface opposite to the surface opposite to the surface irradiated with the polarized ultraviolet light. The liquid crystalline structural units are aligned in the liquid crystal aligning step by heating the retardation layer forming layer so as to reach a glass phase-liquid crystal phase transition temperature of Can be arranged uniformly. For this reason, according to this aspect, a retardation film having a retardation layer having a small haze can be produced.

Here, although it is not clear why the retardation layer in which the crosslinkable liquid crystal material is uniformly arranged can be formed by the alignment imparting step and the liquid crystal alignment step as described above, the above-mentioned “A. The reason is considered to be similar to the reason described in the section “Method for producing retardation film”.
That is, in the orientation imparting step, the photoreactive group of the photoreactive polymer liquid crystal in the retardation layer forming layer is reacted by irradiating the retardation layer forming layer with polarized ultraviolet rays. It imparts orientation. Here, since the photoreactive group is capable of expressing a more uniform alignment regulating force when irradiated with polarized ultraviolet rays having a high degree of polarization, the polarized ultraviolet rays are irradiated in the orientation imparting step. The surface of the formed surface becomes a region where the most uniform orientation regulating force can be expressed.
Accordingly, in the liquid crystal alignment step, the surface of the surface irradiated with the polarized ultraviolet light reaches the glass phase-liquid crystal phase transition temperature of the photoreactive polymer liquid crystal before the surface on the opposite side. By heating the retardation layer forming layer, the liquid crystalline structural units can be arranged in accordance with a uniform alignment regulating force at an initial stage where the liquid crystalline structural units are arranged.
Here, the liquid crystalline structural unit has a property that when a liquid crystalline structural unit existing in a certain portion is aligned, a liquid crystalline structural unit existing in another portion is aligned along the alignment. For this reason, in the liquid crystal alignment step, when a uniform alignment can be formed at the initial stage where the liquid crystalline structural units are aligned, the liquid crystal structure existing in other portions along the uniform alignment is then obtained. It is possible to arrange the units uniformly in a chain.
For this reason, the retardation film produced according to the present embodiment can form the liquid crystalline structural unit having a uniform arrangement over the entire retardation layer. It is thought that it can be made small.

  From the above, according to this aspect, a retardation film having a transparent substrate and a retardation layer formed directly on the transparent substrate without an alignment film and containing a liquid crystalline material, A retardation film having a small haze can be produced.

The method for producing a retardation film of this aspect includes at least the retardation layer forming layer forming step, the orientation imparting step, and the liquid crystal alignment step, and has other steps as necessary. You may do it.
Hereinafter, each process used for the manufacturing method of the retardation film of this aspect is demonstrated in order.

1. Liquid Crystal Alignment Step First, the liquid crystal alignment step used in this embodiment will be described. In this step, the retardation layer forming layer formed in the later-described retardation layer forming layer forming step, the surface of the surface irradiated with the polarized ultraviolet rays in the orientation providing step described later was irradiated with the polarized ultraviolet rays. This is a step of aligning the liquid crystalline structural units by heating so as to reach the glass phase-liquid crystal phase transition temperature of the photoreactive polymer liquid crystal before the surface opposite to the surface.
In the method for producing a retardation film of this embodiment, a retardation film having a small haze can be produced by arranging the liquid crystalline structural units by such a method in this step.

  As described above, this step is a step of aligning the liquid crystalline structural units by heating the retardation layer forming layer. As a heating method used in this step, the orientation imparting is performed. In the process, the retardation layer forming layer is added so that the surface of the surface irradiated with polarized ultraviolet rays has the glass-liquid crystal phase transition temperature of the photoreactive polymer liquid crystal before the opposite surface. It is not particularly limited as long as it can be heated. As such a heating method, a method similar to the method described in the section “A. Method for producing retardation film of first aspect” can be used.

  In this step, the temperature (referred to as Tt) for heating the surface irradiated with polarized ultraviolet light is not less than the glass phase-liquid crystal phase transition temperature (referred to as Tg) of the photoreactive polymer liquid crystal. And the surface of the photoreactive polymer liquid crystal that is lower than the softening temperature of the photoreacted portion and irradiated with the polarized ultraviolet light is a glass phase-liquid crystal of the photoreactive polymer liquid crystal within a predetermined time. The temperature is not particularly limited as long as it can be a phase transition temperature. Such a heating temperature can be appropriately determined according to the glass phase-liquid crystal phase transition temperature of the photoreactive polymer liquid crystal. Especially in this process, it is preferable that the said heating temperature Tt (degreeC) is in the range of (Tg + 20) (degreeC) <= Tt (degreeC). The heating temperature Tt (° C.) in this step is Tt (° C.) <(Tg + 20) (° C.), so that the surface irradiated with the polarized ultraviolet light is irradiated on the surface of the photoreactive polymer liquid crystal within a desired time. This is because it may be difficult to warm to the glass phase-liquid crystal phase transition temperature.

2. Orientation imparting step Next, the orientation imparting step used in this step will be described. In this step, the retardation layer forming layer formed in the retardation layer forming layer forming step described later is irradiated with polarized ultraviolet rays from one side, and the photoreactive polymer liquid crystal in the retardation layer forming layer is This is a step of imparting orientation to the liquid crystalline structural unit to the retardation layer forming layer by reacting a photoreactive group having the same.
Hereinafter, such an orientation imparting step will be described in detail.

  This step is to impart orientation to the retardation layer forming layer by irradiating polarized ultraviolet rays from one side of the retardation layer forming layer. As such, the surface on the transparent substrate side of the phase difference layer forming layer may be used, or the surface opposite to the transparent substrate side may be used. In particular, in this step, it is preferable to irradiate the retardation layer forming layer with polarized ultraviolet rays from the surface of the retardation layer forming layer opposite to the transparent substrate. This is due to the following reason. That is, when irradiating polarized ultraviolet rays to the surface on the transparent substrate side, the polarized ultraviolet rays are irradiated to the retardation layer forming layer through the transparent substrate. Here, when the polarized ultraviolet light passes through the transparent substrate, the polarized ultraviolet light is absorbed or scattered by the transparent substrate, and the intensity of the ultraviolet light is reduced or the polarized light is relaxed. There is a risk that it may be difficult to impart uniform orientation. On the other hand, when polarized ultraviolet rays are irradiated from the surface opposite to the transparent substrate, this is not the case, so it is easy to impart a uniform alignment regulating force to the retardation layer forming layer in this step. Because it becomes.

  In this step, the polarized ultraviolet ray irradiated to the retardation layer forming layer is particularly limited as long as the wavelength is within a range in which the photoreactive group of the photoreactive compound has a photoreactive group. Is not to be done. Such polarized ultraviolet rays can be appropriately selected and used according to the types of the photoreactive group and the crosslinkable functional group.

  In this step, the method for irradiating the retardation layer forming layer with polarized ultraviolet light is not particularly limited as long as it can irradiate the retardation layer forming layer with polarized ultraviolet light in a desired vibration direction. As such a method, the method similar to the method demonstrated in the above-mentioned "A. Manufacturing method of retardation film of 1st aspect" can be used.

3. Next, the phase difference layer forming layer forming step used in this embodiment will be described. This step uses a transparent substrate, and coats a polymer liquid crystal-containing composition containing a liquid crystalline structural unit having liquid crystallinity in the molecule and a photoreactive polymer liquid crystal having a photoreactive group on the transparent substrate. This is a step of forming a retardation layer forming layer on the transparent substrate.
In addition, the retardation layer forming layer formed in this step is a retardation layer that exhibits retardation through the liquid crystal alignment step and the orientation imparting step described above.
Hereinafter, the layer forming process for forming the retardation layer will be described in detail.

(1) Polymer liquid crystal containing composition First, the polymer liquid crystal containing composition used for this process is demonstrated. The polymer liquid crystal-containing composition used in this step contains a photoreactive polymer liquid crystal having a liquid crystalline structural unit exhibiting liquid crystallinity and a photoreactive group in the molecule.

  The photoreactive group possessed by the photoreactive polymer liquid crystal used in this step includes a photochemical reaction caused by irradiation with ultraviolet rays having a specific wavelength, and the retardation layer forming layer formed in this step There is no particular limitation as long as it can provide orientation to the liquid crystalline structural unit. Examples of such photoreactive groups include cinnamate, coumarin, benzylidenephthalimidine, benzylideneacetophenone, diphenylacetylene, stilbazole, uracil, quinolinone, maleinimide, and cinnamilidene acetic acid derivatives.

  The liquid crystalline structural unit possessed by the photoreactive polymer liquid crystal used in this step is not particularly limited as long as it can express a desired retardation by being regularly arranged. What has arbitrary liquid crystallinity can be used according to the use etc. of retardation film manufactured. Among these, in this embodiment, it is preferable to use a liquid crystal structural unit that exhibits a nematic liquid crystal phase. This is because liquid crystalline structural units exhibiting a nematic liquid crystal phase can be easily arranged regularly.

The photoreactive polymer liquid crystal used in this embodiment may have only one photoreactive group or may have a plurality of photoreactive groups.
Further, the photoreactive polymer liquid crystal used in this embodiment may have only one liquid crystalline structural unit or may have a plurality of liquid crystalline structural units.

  Specific examples of the photoreactive polymer liquid crystal used in this embodiment include, for example, a photoreaction in which the main chain represented by the following formula has a structure such as hydrocarbon, acrylate, methacrylate, maleimide, N-phenylmaleimide, and siloxane. For example, a functional polymer liquid crystal.

In the above formulas (V) -1 and (V) -2, x ₁ , y ₁ , and z ₁ are x ₁ + y ₁ + z ₁ = 1, x ₂ , y ₂ is x ₂ + y ₂ = 1, and s is 1 to 1 12, t is 1 to 12, u is 1 to 12, v is 1 to 12, and w is 1 to 12.
X and Y each independently represent none, —COO, —OCO, —N═N—, —C═C—, or —C ₆ H ₄ —.
W ² , W ³ and W ⁴ are each independently —H, —CN, a halogen group, an alkyl group, an alkoxy group, an alkenyl group, an alkenyloxy group, a cyclohexyl group, a cyclohexenyl group, the following formula (VI) -1 to (VI) -8, and at least one of the structures is represented by the following formulas (VI) -1 to (VI) -8.

Furthermore, R ^{22 to} R ³² are each independently an alkyloxy group such as —H, —CN, a halogen group, an alkyl group, or a methoxy group.

  In this embodiment, only one kind of such a photoreactive polymer liquid crystal may be used, or a plurality of kinds of photoreactive compounds may be mixed and used.

  The polymer liquid crystal-containing composition used in this step contains the photoreactive polymer liquid crystal, but may contain other substances as necessary. Examples of such other substances include solvents, plasticizers, surfactants, and silane coupling agents. In particular, in this embodiment, it is preferable to use a solvent as the other configuration. By containing a solvent, for example, even when a polymer liquid crystal-containing composition containing a photoreactive polymer liquid crystal having a high melting point or softening point is used, it can be easily applied at room temperature. It is.

  The solvent is not particularly limited as long as it can dissolve the photoreactive polymer liquid crystal at a desired concentration. As such a solvent, those described in the above section “A. Method for producing retardation film of first aspect” can be used.

  In addition, when the said polymer liquid crystal containing composition contains the said solvent, it does not specifically limit as solid content concentration of the said polymer liquid crystal containing composition, The said polymer liquid crystal containing composition in this process is not limited. An object can be made into arbitrary density | concentration according to the coating method etc. which apply | coat on a transparent substrate.

(2) Transparent substrate Next, the transparent substrate used for this process is demonstrated. The transparent substrate used in this step has transparency, and supports the retardation layer in the retardation film produced according to this embodiment.
Here, the transparent substrate used in this embodiment is the same as that described in the above-mentioned section “A. Method for producing retardation film of first embodiment”, and thus the description thereof is omitted here.

(3) Method for forming retardation layer forming layer This step is to form the retardation layer forming layer by coating the above-mentioned polymer liquid crystal-containing composition on the transparent substrate. The method for forming the retardation layer-forming layer using the polymer liquid crystal-containing composition is the same as the method described in the section “A. Method for producing retardation film of first aspect” above. Explanation here is omitted.

4). Other Steps The method for producing a retardation film of this aspect may include steps other than the above steps. Such other steps are not particularly limited, and a step capable of imparting a desired function to the retardation film produced according to this embodiment can be arbitrarily used. Examples of such other steps include a step of irradiating the retardation layer with ultraviolet rays after the liquid crystal alignment step. By irradiating the retardation layer with ultraviolet rays after the liquid crystal alignment step, the photoreactive group of the photoreactive polymer liquid crystal that has not reacted by the irradiation with polarized ultraviolet rays in the orientation imparting step is reacted to form a crosslinked structure. By taking it, the heat resistance of the retardation layer is improved.

5. Retardation Film A retardation film produced by the method for producing a retardation film of this embodiment has the transparent substrate and a retardation layer formed on the transparent substrate and containing the photoreactive polymer liquid crystal. It will be a thing.

  Such a retardation film can be used, for example, as an optical compensation film (for example, a viewing angle compensation film) used in a liquid crystal display device, an elliptically polarizing plate, a circularly polarizing plate, and a brightness enhancement plate.

  The present invention is not limited to the above embodiment. The above-described embodiment is an exemplification, and the present invention has any configuration that has substantially the same configuration as the technical idea described in the claims of the present invention and that exhibits the same effects. Are included in the technical scope.

  Next, the present invention will be described more specifically by showing examples.

(Synthesis Example 1)
Synthesis of poly [1- [6- [4- [2-methoxy-4-[(E) -2-methoxycarbonylvinyl] phenoxycarbonyl] phenoxy] hexyloxycarbonyl] -1-methylethylene] (formula A below)

  1- [6- [4- [2-methoxy-4-[(E) -2-methoxycarbonylvinyl] phenoxycarbonyl] phenoxy] hexyloxycarbonyl] -1-methylethylene 4.91 parts by mass, 2,2 ′ -0.018 parts by mass of azobisisobutyronitrile was dissolved in 28 parts by mass of dehydrated tetrahydrofuran. Heated at 65 ° C. for 25 hours under nitrogen atmosphere. The obtained reaction solution was added dropwise to 800 ml of methanol, the precipitate was filtered, and dried under reduced pressure. The obtained solid was dissolved in 5 parts by mass of chloroform, the solution was dropped into 1 L of methanol, the precipitate was filtered, and then dried under reduced pressure. Poly [1- [6- [4- [2-methoxy-4-[(E) -2-methoxycarbonylvinyl] phenoxycarbonyl] phenoxy] hexyloxy having a weight average molecular weight of 116000 (GPC: solvent THF, converted to polystyrene) 3.6 parts by mass of [carbonyl] -1-methylethylene] were obtained.

(Synthesis Example 2)
Synthesis of poly [7-{[4- (6-methacryloyloxy) hexyloxy] benzoyloxy} coumarin]

Chem. Mater. , Vol. 13, no. Synthesis was performed in the same manner as described in 2,2001,694-703 to obtain 7-{[4- (6-methacryloyloxy) hexyloxy] benzoyloxy} coumarin.
7-{[4- (6-Methacryloyloxy) hexyloxy] benzoyloxy} coumarin 1.1 parts by mass, 2,2′-azobisisobutyronitrile 0.04 parts by mass, mercaptopropionic acid 0.06 parts by mass Dissolved in 7 parts by mass of dehydrated tetrahydrofuran. The mixture was heated at 65 ° C. for 19 hours under a nitrogen atmosphere. The obtained reaction solution was added dropwise to 600 ml of methanol, the precipitate was filtered, washed with methanol, and dried under reduced pressure at room temperature. 15 g of methyl ethyl ketone was added to the obtained solid, and after stirring, the portion insoluble in methyl ethyl ketone was removed by filtration. The methyl ethyl ketone solution was added dropwise to 800 ml of methanol, and the precipitate was filtered and dried under reduced pressure. As a result, 0.25 parts by mass of poly [7-{[4- (6-methacryloyloxy) hexyloxy] benzoyloxy} coumarin] having a weight average molecular weight of 5100 (GPC: solvent THF, polystyrene conversion) was obtained. This polymer exhibited liquid crystallinity in the range of 51 ° C to 77 ° C.

1. Example 1
(Production of shielding layer)
Pentaerythritol triacrylate (PET-30, Nippon Kayaku) 40 parts by mass, photopolymerization initiator 1-hydroxy-cyclohexyl-phenylketone (trade name IRGACURE184, manufactured by Ciba Specialty Chemicals) 2 parts by mass, methyl ethyl ketone 29 parts by mass A solution consisting of 58 parts by mass of toluene is bar-coated on a triacetylcellulose film (FT-T80UZ, manufactured by Fuji Photo Film Co., Ltd.), dried at 80 ° C. for 3 minutes, and then irradiated with a UV irradiation device (Fusion UV Systems Japan Co., Ltd.). A light-shielding layer having a thickness of 1 μm was produced by irradiating with an ultraviolet ray of 70 mJ / cm ² under a nitrogen atmosphere using a light source (manufactured, light source: H bulb).

(Preparation of UV curable composition)
Photoreactive compound: poly [1- [6- [4- [2-methoxy-4-[(E) -2-methoxycarbonylvinyl] phenoxycarbonyl] phenoxy] hexyloxycarbonyl] -1-methylethylene] (synthesis) Compound of Example 1) 2 parts by mass, crosslinkable liquid crystal material: compound represented by the following formula (B) 8 parts by mass, photopolymerization initiator: 1-hydroxy-cyclohexyl-phenyl ketone (trade name IRGACURE184, Ciba Specialty) Chemicals) 0.004 parts by mass was dissolved in methyl ethyl ketone to prepare a UV curable composition as a 10% solid content solution.

  Here, a and b in the above formula (B) are integers of 2 to 5, respectively.

(Formation of retardation layer)
The ultraviolet curable composition was coated on the shielding layer prepared in the above step with a wire bar, and heated and dried at 30 ° C. for 3 minutes to form a retardation layer forming layer.
A shot WG280 and Asahi Spectroscopic SU0325 were placed as a cut filter in an ultraviolet irradiation device using a 500 W Deep UV lamp to limit the wavelength, and further, the wire grid polarizing plate was transmitted to obtain polarized ultraviolet rays. From the surface opposite to the transparent substrate triacetylcellulose, polarized ultraviolet rays were irradiated in the air at 8 mJ / cm ² from the direction perpendicular to the film surface of the retardation layer forming layer. Here, the irradiation amount of polarized ultraviolet rays was calculated from the irradiation intensity and the irradiation time, and the irradiation intensity was measured with a UV RADIO METER UVR-400A (manufactured by ASONE Corporation) using a sensor S-310 (measurement range 280 to 360 nm). . Then, after irradiating polarized ultraviolet light, it was placed in an oven set at 100 ° C. and heated for 3 minutes so that warm air was applied from the side irradiated with polarized ultraviolet light. After aligning the liquid crystal by this heating, 120 mJ / cm ² non-polarized ultraviolet rays were irradiated in a nitrogen atmosphere to cure the coating film. Thereby, the aligned liquid crystal was fixed, and a retardation film was produced. The thickness of this retardation layer was 0.8 μm.

(Evaluation)
The retardation film thus obtained was measured for an in-plane retardation (Re) at a wavelength of 590 nm using an automatic birefringence measuring apparatus (manufactured by Oji Scientific Instruments, automatic birefringence meter KOBRA-WR). Met. Moreover, it was 1.5% when haze was measured with the turbidimeter NDH2000 (made by Nippon Denshoku Industries Co., Ltd.).

2. Example 2
(Preparation of polymer liquid crystal-containing composition)
Photoreactive polymer liquid crystal: 2 parts by mass of poly [7-{[4- (6-methacryloyloxy) hexyloxy] benzoyloxy} coumarin] (Compound of Synthesis Example 2) is dissolved in methyl ethyl ketone to obtain a 5% solid content solution. A polymer liquid crystal-containing composition was prepared.

(Formation of retardation layer)
The polymer liquid crystal-containing composition was coated on the shielding layer prepared in the same process as in Example 1 with a wire bar, and dried by heating at 30 ° C. for 3 minutes to form a retardation layer forming layer.
A shot WG280 and Asahi Spectroscopic SU0325 were placed as a cut filter in an ultraviolet irradiation device using a 500 W Deep UV lamp to limit the wavelength, and further, the wire grid polarizing plate was transmitted to obtain polarized ultraviolet rays. From the surface opposite to the transparent substrate triacetylcellulose, polarized ultraviolet rays were irradiated in the air at 20 mJ / cm ² from the direction perpendicular to the film surface of the retardation layer forming layer. After irradiating polarized ultraviolet rays, it was placed in an oven set at 65 ° C. and heated for 3 minutes so that warm air hits the surface irradiated with polarized ultraviolet rays. Thereby, the liquid crystal was aligned, and a retardation film was produced. The thickness of this retardation layer was 0.8 μm.

(Evaluation)
The retardation film thus obtained had an in-plane retardation at a wavelength of 590 nm of 50 nm and a haze of 2%.

3. Comparative Example Heating after irradiation with polarized ultraviolet rays was performed for 3 minutes so that triacetylcellulose was in contact with a 100 ° C. hot plate, and heating was performed from the opposite side to the surface irradiated with polarized ultraviolet rays. A sample was prepared. The obtained film had an in-plane retardation at a wavelength of 590 nm of 15 nm and a haze of 18%.

It is the schematic which shows an example of the manufacturing method of the phase difference film of the 1st aspect of this invention. It is the schematic which shows an example of the manufacturing method of the phase difference film of the 2nd aspect of this invention. It is the schematic which shows a part of common liquid crystal display device typically.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Transparent substrate 2A, 2B ... Phase difference layer 2A ', 2B' ... Phase difference layer formation layer 10A, 10B ... Phase difference film 100 ... Liquid crystal display device 101 ... Liquid crystal cell 102A, 102B ... Polarizing plate

Claims (5)

By applying a UV curable composition containing a crosslinkable liquid crystal material having a crosslinkable functional group and a photoreactive compound having a photoreactive group on the transparent substrate, using the transparent substrate, the transparent A phase difference layer forming layer forming step of forming a phase difference layer forming layer on the substrate;
Alignment imparting step in which the retardation layer forming layer is irradiated with polarized ultraviolet rays from one side and the photoreactive compound is reacted to cause the retardation layer forming layer to exhibit orientation with respect to the crosslinkable liquid crystal material; and ,
The crystal-liquid crystal phase transition temperature of the crosslinkable liquid crystal material is such that the surface of the phase difference layer forming layer irradiated with the polarized ultraviolet light has a surface opposite to the surface opposite to the surface irradiated with the polarized ultraviolet light. A liquid crystal alignment step of aligning the crosslinkable liquid crystal material by heating the retardation layer forming layer to reach
A liquid crystal cross-linking step of cross-linking the cross-linkable liquid crystal material aligned in the liquid crystal alignment step. The method for producing a retardation film according to claim 1, wherein the photoreactive compound has at least one photoreactive group represented by the following formulas (I) and (II).

(In the above formulas (I) and (II), A ¹ , A ² , A ³ are each independently unsubstituted or optionally substituted with fluorine, chlorine, cyano, alkyl, alkoxy, or alkyloxycarbonyl. 1,4-phenylene, 4,4′-biphenylene, 1,4-naphthylene, 2,6-naphthylene, pyridine-2,5-diyl, pyrimidine-2,5-diyl, 1,3-dioxane-2,5 -Represents diyl, piperidine-1,4-diyl or piperazine-1,4-diyl.
R ¹ represents hydrogen, alkyl having 1 to 4 carbons, or alkoxy having 1 to 4 carbons.
R ² represents hydrogen, alkyl having 1 to 4 carbon atoms, alkoxy having 1 to 4 carbon atoms, alkyloxycarbonyl having 2 to 6 carbon atoms, or cyano.
R ³ represents hydrogen, unsubstituted or alkyl having 1 to 20 carbon atoms substituted with any fluorine or chlorine. ) By applying a polymer liquid crystal-containing composition containing a photoreactive polymer liquid crystal having a liquid crystalline structural unit exhibiting liquid crystallinity in the molecule and a photoreactive group on the transparent substrate using a transparent substrate, A retardation layer forming layer forming step of forming a retardation layer forming layer on the transparent substrate;
Alignment imparting step in which the retardation layer forming layer is irradiated with polarized ultraviolet rays from one side and the photoreactive group is reacted to cause the retardation layer forming layer to exhibit orientation with respect to the liquid crystalline structural unit; ,
The surface of the surface of the retardation layer forming layer irradiated with the polarized ultraviolet light is a glass phase-liquid crystal of the photoreactive polymer liquid crystal before the surface opposite to the surface irradiated with the polarized ultraviolet light. And a liquid crystal alignment step of aligning the liquid crystalline structural units by heating the retardation layer forming layer so as to reach a phase transition temperature.   The liquid crystal alignment step is to heat the retardation layer forming layer only from the surface side irradiated with the polarized ultraviolet rays in the orientation imparting step. The method for producing a retardation film according to claim 3.   The orientation imparting step irradiates the retardation layer forming layer with polarized ultraviolet rays from the side of the retardation layer forming layer opposite to the transparent substrate. The method for producing a retardation film according to any one of claims 1 to 4.

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