JP6434692B2 - Manufacturing method of optical element having optical anisotropy and optical element having optical anisotropy - Google Patents

Description

  The present invention relates to a method for producing an optical element having optical anisotropy and an optical element produced by the method, and in particular, production of an optical element including application of a photosensitive polymer material using a solvent containing a nonpolar solvent. Method, and optical element produced by using the method, particularly retardation film having the characteristics of negative C plate, retardation film having biaxial optical anisotropy, and inclined biaxial refractive index ellipsoid It relates to a retardation film having optical anisotropy represented by the following.

  Liquid crystal display devices (LCDs) are widely used for displaying information on mobile phones, computer monitors, televisions, and the like. Depending on the driving method of the LCD, various methods such as Twisted Nematic LCD (TN LCD), Vertical Alignment LCD (VA LDC), and In Plane Switching LCD (IPS LCD) can be used. Many of these LCDs can obtain high-contrast images when viewed from the front. However, depending on the LCD, when viewed from an oblique direction, the axial angle of the disposed polarizing plate deviates from 90 °, and light leakage occurs due to the optical anisotropy of the liquid crystal molecules in the LCD cell. Decrease and color change will occur.

  In order to solve this problem, various retardation films have been used for LCDs. The retardation film is an optically anisotropic element having birefringence that allows linearly polarized components that vibrate in directions of principal axes perpendicular to each other to pass therethrough and that provides a necessary phase difference between the two components. The retardation film is also used in the liquid crystal display field for the purpose of improving the viewing angle of the liquid crystal display device as described above, and a retardation film having various characteristics according to the characteristics of the liquid crystal cell is used. The

For example, Patent Document 1 (Japanese Patent Application Laid-Open No. 2001-109909) describes that in a vertical alignment mode liquid crystal display device, an A plate and a negative C plate are disposed between upper and lower polarizing plates and a liquid crystal cell, respectively. Has been. Here, the A plate has a uniaxial optical anisotropy in which the optical axis is parallel to the film surface, and the C plate has a uniaxial optical anisotropy in which the optical axis is perpendicular to the film surface. It is a film. In particular, a retardation film in which the main refractive index of the refractive index ellipsoid has a relationship of nx = ny> nz is called a negative C plate.
In addition, a retardation film having a relationship of nx>ny> nz (Nz coefficient = 1 or more) (having biaxial optical anisotropy) of the three main refractive indices of the refractive ellipsoid is VA mode, IPS It is used in many types of liquid crystal display devices such as modes. Furthermore, a retardation film having an optical characteristic in which a refractive index ellipsoid is inclined may be useful as an optical compensation film for widening the viewing angle of liquid crystal display devices such as a TN mode and an ECB mode.

In the retardation film, in order to obtain desired optical characteristics, it is desired to arbitrarily control the size of the three main refractive indexes of the refractive ellipsoid of the film.
As a conventionally used method for producing a retardation film, a polymer material such as a cycloolefin polymer or polycarbonate is stretched, a polymer chain is oriented, a refractive index in the stretching direction, and a refraction in a direction perpendicular to the stretching direction. There is a method for making a difference in rate.
In the retardation film produced by such a stretching process, a retardation film having the characteristics of a negative C plate and a retardation film having biaxial optical characteristics can be produced. However, since this manufacturing method is based on a process of stretching a polymer material, it is difficult to reduce the film thickness. Therefore, it is difficult to achieve the thinning required for a liquid crystal display device of a mobile phone.
Furthermore, since the production of the film is based on the stretching process of the polymer material, the molecules are oriented in the stretching direction parallel to the film surface, and the optical property that the refractive index ellipsoid is inclined with respect to the film surface is substantially Impossible. Furthermore, special techniques, large-scale equipment, and complicated processes are required to obtain specific optical characteristics uniformly with high accuracy over a wide film area.

As a method for producing a thin retardation film, for example, a liquid crystal compound is aligned in Patent Document 2 (Japanese Patent Publication No. 11-513019), Patent Document 3 (Japanese Patent Publication No. 11-513360), and this alignment. A method of fixing is proposed. A method for obtaining a thin film having desired optical characteristics by such means has been proposed. For example, Patent Document 4 (Japanese Patent Application Laid-Open No. 2007-291060) discloses a lyotropic surface on a hydrophobic surface. A method is described in which the orientation of liquid crystal (L L C) is fixed and a retardation film having the characteristics of a negative C plate is produced.
Patent Document 5 (Re-Table 2011/007669) proposes a method for producing an optically anisotropic layer having the characteristics of a negative C plate by fixing the orientation of a cholesteric liquid crystal having a helical structure by crosslinking or polymerization. Has been.

  As a method for producing a birefringent film in which the optical axis is inclined with respect to the film surface, there is a method in which a rod-like liquid crystal compound or a discotic liquid crystal compound is arranged on a stretched film or a substrate subjected to alignment treatment by rubbing or light irradiation. For example, Patent Document 6 (Japanese Patent Laid-Open No. 7-287119) and Patent Document 7 (Japanese Patent Laid-Open No. 7-287120) describe a method of arranging discotic liquid crystals on a rubbing alignment film and a SiO oblique deposition alignment film. Has been. As a similar method, Patent Document 8 (Japanese Patent Laid-Open No. 10-278123) describes a method of aligning a discotic liquid crystal containing a photopolymerization initiator on a photo-alignment film and fixing the alignment by light irradiation. ing.

JP 2001-109909 A Japanese National Patent Publication No. 11-513019 Japanese National Patent Publication No. 11-513360 JP 2007-291060 A Table 2011/007669 JP-A-7-287119 JP 7-287120 A JP 10-278123 A

  In the methods described in Patent Documents 4 and 5, a retardation film having the characteristics of a relatively thin negative C plate can be produced. However, in the method described in Patent Document 4, the surface of the substrate needs to be treated in advance in a hydrophobic manner, and the manufacturing process becomes complicated. In the method described in Patent Document 5, it is necessary to make the helical pitch sufficiently small in order to prevent light interference due to the helical structure (for example, the helical pitch is 200 nm or less). In addition, in order to induce such a helical structure, it is necessary to add an optically active compound, and the optically active compound should be uniformly mixed with the polymerizable liquid crystal composition so as not to affect the optical properties such as haze generation. Is essential. For this reason, appropriate selection of the optically active compound and addition amount control are required.

  In the method of aligning the liquid crystal compound on the alignment film described in Patent Documents 6, 7, 8 and the like, it is possible to make the film thinner as compared with the stretching process, and the optical axis is inclined with respect to the film surface. A retardation film can be obtained. However, the characteristics of the refractive index ellipsoid of the obtained retardation film depend on the optical characteristics of the liquid crystal compound to be aligned. Here, the rod-like liquid crystal compound and the discotic liquid crystal compound have optically uniaxial characteristics, and the optical characteristics of the obtained retardation film are uniaxial, and exhibit optically biaxial characteristics. It is difficult. Even when the liquid crystalline compound is tilted, the optical properties of the film are limited to those in which a uniaxial refractive index ellipsoid is tilted or hybridly aligned. Therefore, with the methods described in Patent Documents 6, 7, and 8, it is difficult to develop optical characteristics in which the biaxial refractive index ellipsoid is inclined. Furthermore, there are problems such as complicated processes such as alignment treatment of the alignment film and alignment of the liquid crystal material.

  An object of this invention is to provide the manufacturing method of the phase difference film which can provide a thin phase difference film compared with the conventional phase difference film manufactured by the extending | stretching method by a simple method. The present invention also provides optical characteristics of an optical element manufactured by such a method, particularly a retardation film having a desired optical characteristic that is thin compared to a retardation film obtained by a conventional stretching method, particularly a negative C plate. It is an object of the present invention to provide a retardation film having optical properties of a biaxial refractive index ellipsoid, and a retardation film having optical properties in which the biaxial refractive index ellipsoid is inclined.

  As a result of diligent research to solve the above problems, the present inventor applied a liquid crystalline polymer material containing a structural unit represented by a specific chemical formula to form a coating film. It has been found that a thin film having optical anisotropy can be obtained by performing molecular orientation treatment. Furthermore, as a result of repeated research on a method for controlling the optical anisotropy of the film, by applying the liquid crystalline polymer material using a solvent containing an aprotic polar solvent, The alignment control becomes very easy, and by performing an alignment treatment by appropriately combining drying and heat treatment of the coating film with light irradiation as necessary, the optical characteristics of the negative C plate, biaxial optical anisotropy, The inventors have found that desired optical anisotropy such as optical anisotropy indicated by a biaxial refractive index ellipsoid inclined with respect to the film can be reliably imparted to the film, and the present invention has been completed.

The method for producing an optical element according to the present invention includes:
Applying a liquid crystalline polymer material containing a structural unit represented by chemical formula (1) to a substrate to form a coating film;
An orientation control step of imparting a predetermined orientation to the liquid crystalline polymer material in the coating film,
An optical element manufacturing method, wherein the liquid crystalline polymer material is applied using a solvent containing an aprotic polar solvent.

  Here, t represents an integer of 0 to 3, and R represents at least one selected from the group consisting of hydrogen, an alkyl group, an alkyloxy group, and halogen.

  In the method for manufacturing an optical element, in the chemical formula (1) of the structural unit, t may be 1 and R may be hydrogen. That is, the chemical formula of the structural unit may be represented by the following chemical formula (2).

  In the method for producing an optical element, the aprotic polar solvent is selected from the group consisting of tetrahydrofuran (THF), diethyl carbonate, propyl carbonate, N, N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO). It may be at least one kind.

  In the method for producing an optical element, the liquid crystalline polymer material may be provided with photocrosslinkability.

  In the optical element manufacturing method, the orientation control step preferably includes a heat treatment step for heating the coating film.

  In the method for manufacturing an optical element, the alignment control step may further include a light irradiation step of performing light irradiation on the coating film after the alignment control step.

  In the light irradiation step, the coating film may be irradiated with polarized light from a predetermined direction. For example, in the light irradiation step, the coating film may be irradiated with polarized light from the normal direction. The light applied to the coating film may be linearly polarized ultraviolet light.

  On the other hand, in the light irradiation step, the coating film may be irradiated with polarized light and / or non-polarized light from the tilt direction. In this case, for example, the coating film may be irradiated with polarized light from the normal direction and further irradiated with non-polarized light from a direction inclined with respect to the coating film. Specifically, for example, linearly polarized ultraviolet light may be applied to the surface of the coating film from an inclined direction. Alternatively, non-polarized ultraviolet light may be irradiated from a direction inclined with respect to the coating film. Alternatively, mixed light of linearly polarized ultraviolet light and non-polarized ultraviolet light may be irradiated. In this case, for example, unpolarized ultraviolet light may be irradiated from a direction inclined with respect to the surface of the coating film while linearly polarized ultraviolet light is irradiated to the coating film from the normal direction.

  In the method for manufacturing an optical element, the orientation control step may include a drying step of drying the coating film before the heat treatment. You may perform a drying process before the said light irradiation process.

  In the optical element manufacturing method, the coating film may be further irradiated with non-polarized ultraviolet light after the heat treatment in the orientation control step.

  The optical element of the present invention is an optical element manufactured by the above manufacturing method. The optical element may be an optical film.

  One aspect of the optical element of the present invention is a retardation film having the optical anisotropy of a negative C plate produced by the production method described above.

Another aspect of the optical element of the present invention is a retardation film having biaxial optical anisotropy manufactured by the above-described manufacturing method.
Another aspect of the optical element of the present invention is a retardation film having optical anisotropy in which a biaxial refractive index ellipsoid manufactured by the above-described manufacturing method is inclined with respect to the surface.

  According to the present invention, a thin film type having desired optical characteristics such as the optical anisotropy of the negative C plate, the biaxial optical anisotropy, and the optical anisotropy shown by the inclined biaxial refractive index ellipsoid. The optical element (for example, retardation film) can be provided by a simple method.

In one Embodiment of this invention, it is a schematic diagram which shows arrangement | positioning of the side chain of a polymer in the coating film after film forming. It is a schematic diagram which shows arrangement | positioning of the side chain of the polymer after irradiating polarized light to the coating film shown in FIG. 1, and heat-processing.

Hereinafter, the present invention will be further described based on embodiments.
[Method of manufacturing optical element]
The method of manufacturing an optical element according to an embodiment of the present invention includes a step of applying a liquid crystalline polymer material containing a structural unit represented by Chemical Formula 1 to a substrate to form a coating film,
Including an orientation control step of imparting a predetermined orientation to the liquid-writing polymer material in the coating film,
An optical element manufacturing method, wherein the photoreactive polymer material is applied using a solvent containing an aprotic polar solvent.
Moreover, this manufacturing method may include the light irradiation process of performing light irradiation to a coating film further after an orientation control process as needed.

  Here, t represents an integer of 0 to 3, and R represents hydrogen, an alkyl group (for example, a C1-6 alkyl group, preferably a C1-4 alkyl group), an alkyloxy group (for example, a C1-6 alkyloxy group, preferably C1-4 alkyloxy group) and at least one selected from the group consisting of halogen (for example, fluorine atom, chlorine atom and the like).

  In the chemical formula of the structural unit, t may be 1 and R may be hydrogen. That is, the chemical formula of the structural unit may be represented by the following chemical formula (2).

[Coating process]
The structural unit represented by Chemical Formula 1 or Chemical Formula 2 is a structural unit of the side chain of the side chain type liquid crystalline polymer material. Therefore, the liquid crystalline polymer of the present invention is a liquid crystalline polymer having a carboxyl group at the end of the side chain. This liquid crystalline polymer is a material that develops a liquid crystal phase even if the structure does not contain a mesogenic group by dimerization of the carboxyl group at the end of the side chain by hydrogen bonding.

  The above-mentioned side chain type liquid crystalline polymer material has a main chain to which side chains including the above structural units are joined. Examples of the material constituting the main chain include hydrocarbons, acrylates, methacrylates, siloxanes, maleimides, N-phenylmaleimides, and the like.

  Such a liquid crystalline polymer material may be a single polymer composed of the same repeating unit or a copolymer of units having side chains having different structures. Moreover, you may add the crosslinking agent for improving heat resistance and solvent resistance to such an extent that liquid crystallinity is not impaired. As a crosslinking agent added in order to improve heat resistance, crosslinking agents, such as isocyanate material and an epoxy material, can be mentioned. Photosensitive side chains may be introduced into the liquid crystalline polymer itself.

  In the present invention, the liquid crystalline polymer material is dissolved in a solvent containing an aprotic polar solvent to form a solution. Here, as the aprotic polar solvent, an appropriate solvent can be selected as long as the liquid crystalline polymer material can be dissolved. For example, tetrahydrofuran (THF), methyl tert-butyl ether, 1,4-dioxane, diethylene glycol dimethyl ether. (Diglyme), ether solvents such as ethylene glycol dimethyl ether, 1,3-dioxolane, 2-methyltetrahydrofuran; carbonate solvents such as dimethyl carbonate, diethyl carbonate, propyl carbonate, propylene carbonate, ethylene carbonate; N -Methylpyrrolidone (NMP), N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), 1,3-dimethyl-2-imida It can be used sulfolane, acetonitrile, the one selected from propionitrile or a mixture of two or more; Rijinon (DMI), amide solvents such as hexamethylphosphoramide (HMPA). Among these, tetrahydrofuran (THF), diethyl carbonate, propyl carbonate, N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO) and the like can be preferably used. These solvents may be used alone or in combination of two or more.

  The concentration of the liquid crystalline polymer material in the coating solution is not particularly limited as long as it can be used for forming a coating film, but may be, for example, 5 to 50 wt%, 8 to 40 wt%, or 10 It may be ˜25% by weight.

  Next, a solution in which the liquid crystalline polymer material is dissolved is applied to the substrate to form a coating film. The substrate used for film formation may be a glass substrate or a transparent film having low birefringence (preferably optical isotropic) optical characteristics. Alternatively, an optical film such as a polarizing film or a retardation film, or a laminate of a plurality of optical films may be used as the base material as long as the optical properties of the base material are not impaired in the orientation control step described later. A preferred substrate may be, for example, a polycarbonate film, a cycloolefin polymer film, or the like.

  The liquid crystal polymer solution can be applied to the substrate by a method such as spin coating or casting.

[Orientation control process]
Next, in the orientation control step, a film having specific optical anisotropy is formed by controlling the orientation of the liquid crystalline polymer material in the coating film, particularly the orientation of the side chain.
The orientation control process may include a process of drying the coating film. In the orientation control step, the coating film is irradiated with light from the normal direction or the direction inclined from the normal line as necessary. In the orientation control step, the coating film is preferably heat treated.
Hereinafter, an optical element having characteristics of a negative C plate, an optical element having biaxial optical anisotropy, and an optical element having optical anisotropy indicated by an inclined biaxial refractive index ellipsoid are formed. Will be described.

[Formation of negative C plate]
In this embodiment, the solvent may first be removed in the process of drying the coating film. Although the coating film has no in-plane anisotropy during film formation, the side chain portion tends to be slightly in-plane oriented in the process of drying the solvent. As a result of intensive studies by the present inventor, it has been found that the tendency of side chains to be oriented in-plane is enhanced by forming a film using a solvent to which an aprotic polar solvent is added.
Usually, after the formation of the coating film, the solvent volatilizes relatively quickly, so that it is not necessary to provide a special process for drying, but a drying process may be provided in the orientation control process if necessary. In the drying step, for example, the drying step may be a step in which the coating film is allowed to stand for 3 minutes or more in a temperature range from room temperature to 60 ° C.

  Next, due to molecular movement after drying, the side chains that were not aligned in the plane and the side chains that were arranged in the out-of-plane direction were aligned in the plane under the influence of the in-plane aligned side chains that occurred during the drying process. To do. As a result, the optical characteristics of the negative C plate are induced in the entire film.

  This orientation due to molecular motion after drying is promoted by heating the coating film (heat treatment step). The heating temperature of the coating film is desirably higher than the softening point of the side chain portion, and preferably lower than the isotropic phase transition temperature of the liquid crystalline polymer. If the liquid crystalline polymer is heated to an isotropic phase transition temperature at which the liquid crystallinity is disturbed, the alignment is disturbed and desired optical characteristics cannot be obtained. Other conditions (heating time, etc.) are not particularly limited as long as the orientation of the liquid crystalline polymer can be obtained. For example, after reaching a predetermined temperature (for example, 120 to 135 ° C.), the temperature may be lowered as it is, for example, after reaching a predetermined temperature (for example, 120 to 135 ° C.) and maintained for a predetermined time, the temperature may be decreased.

[Formation of biaxial optical anisotropic element]
In addition, the liquid crystal polymer material having the structural unit represented by the above chemical formula 1 or 2 also has characteristics as a photoreactive liquid crystal polymer material. As a result of diligent research, the present inventor has formed a film using a solvent to which an aprotic polar solvent has been added during film formation of the liquid crystalline polymer material, and then polarized light of a predetermined wavelength, preferably linear, from a predetermined direction. It has been found that biaxial optical characteristics are easily developed by irradiating polarized light. In addition, it is preferable that light irradiation is performed after drying of a coating film.

In order to advance the alignment control by the photoreaction, it is necessary to irradiate light having a wavelength that allows the photosensitive group to react. This wavelength is generally 200-500 nm, and in particular, the effectiveness of 250-400 nm is often high. Accordingly, the light to be irradiated preferably has a maximum value of intensity in the wavelength range of 200 to 500 nm, and more preferably ultraviolet light. As the ultraviolet light, it is preferable to use ultraviolet light having a maximum value of intensity at a wavelength in the range of 200 to 400 nm, preferably at a wavelength in the range of 250 to 400 nm. For example, a high pressure mercury lamp may be used as the light source. Dose may be for example 20mJ / ^{cm 2} ~300mJ / ^cm 2 approximately.
In this embodiment, the coating film formed in the coating film forming step may be irradiated with linearly polarized light.

  Hereinafter, a process in which biaxial optical anisotropy is exhibited by irradiating the coating film with linearly polarized ultraviolet light from the normal direction will be described with reference to the drawings.

  FIG. 1 is a schematic diagram showing a state of a coating film after film formation and before performing polarized light irradiation. In general, a film formed has no in-plane anisotropy at the time of film formation, and the side chain portion of the photosensitive liquid crystalline polymer does not face a specific direction in the surface. Since the film is formed with a solvent to which a solvent is added, the side chain tends to be oriented in the plane. In FIG. 1, the side chains are shown as cylinders. The side chain 1a is a side chain located in the vibration direction of the linearly polarized light to be irradiated and in a direction perpendicular to the irradiation direction, and has high photosensitivity. The side chain 1b is a side chain with poor photosensitivity, and the side chain 1c is a side chain oriented in an out-of-plane direction (a direction close to the normal line of the coating film).

  When the coating film is irradiated with polarized light, the photoreaction of the highly photosensitive side chain 1a proceeds preferentially. In order to advance this photoreaction, irradiation with linearly polarized light having a wavelength with which the photosensitive group can react is required. As described above, it is preferable to irradiate ultraviolet light having a maximum value of intensity in the wavelength range of 200 to 400 nm converted into linearly polarized light.

  FIG. 2 is a schematic diagram showing the state of the coating film after irradiation with polarized light. Due to molecular motion after polarization exposure, a part of the side chain 2b that did not cause photoreaction and the side chain 2c arranged in the out-of-plane direction before light irradiation are aligned in the same direction as the side chain 2a subjected to photoreaction. To do. On the other hand, depending on the irradiation intensity of polarized light, except for some side chains oriented in the same direction as the photoreacted side chain 2a, the side chains that were arranged in parallel after coating and did not cause photoreaction The arrangement does not change. As a result, an optical characteristic indicated by a biaxial refractive index ellipsoid (nx> ny> nz) is induced in the coating film. At that time, the shape of the biaxial refractive index ellipsoid varies depending on the arrangement ratio of the material side chains.

  Moreover, you may heat-process further after light irradiation as needed. That is, in this case, the optical element manufacturing method may include an alignment control step, a light irradiation step, and a heating step. Orientation by molecular motion after polarization exposure is promoted by heating the coating film. As heating conditions for the coating film, the same conditions as those described in the formation of the negative C plate may be used.

[Formation of optical element shown by tilted biaxial refractive index ellipsoid]
In particular, in the light irradiation step described in the formation of the biaxial optically anisotropic element described above, polarized light and / or from the direction inclined with respect to the surface of the coating film (in other words, the direction inclined with respect to the normal line of the coating film). Alternatively, by irradiating non-polarized light, an optical element represented by an inclined refractive index ellipsoid can be formed on the surface of the coating film.

  The light to be irradiated is preferably linearly polarized light, particularly ultraviolet light linearly polarized light. However, when light is irradiated from an inclined direction, even when non-polarized ultraviolet light or a mixed light of non-polarized ultraviolet light and polarized ultraviolet light is irradiated, the optical characteristic indicated by the inclined biaxial refractive index ellipsoid Characteristics can be developed. For example, it is possible to develop optical characteristics indicated by a tilted biaxial refractive index ellipsoid even when irradiating linearly polarized ultraviolet light from the normal direction of the coating film and irradiating non-polarized ultraviolet light from the tilt direction. it can.

  When irradiating light from the inclined direction with respect to the surface of the coating film, the angle with respect to the surface can be selected from a wide range of more than 0 ° and less than 90 °, but is preferably more than 0 ° and 75 ° or less. There may be.

  After the light irradiation or after the second drying step after the light irradiation, the coating film is heated in the same manner as described above, thereby having optical characteristics shown by a biaxial refractive index ellipsoid inclined with respect to the surface. An optical element can be manufactured.

  Embodiments of forming an optical element having the characteristics of a negative C plate, an optical element having biaxial optical anisotropy, and an optical element having optical anisotropy indicated by an inclined biaxial refractive index ellipsoid In any of the above, if necessary, in order to improve the solvent resistance, the obtained coating film may be irradiated with light of a predetermined wavelength (for example, irradiation of non-polarized ultraviolet light).

  The film thickness of the film formed on the substrate by the above method can be 20 μm or less, preferably 0.1 to 15 μm, more preferably 0.5 μm to 10 μm.

  Below, based on an Example, this invention is demonstrated in detail. However, as long as there is no change in the gist of the present invention, it is not limited to the following examples.

(Monomer 1)
4- (6-Hydroxyhexyloxy) cinnamic acid was synthesized by heating p-coumaric acid and 6-chloro-1-hexanol under alkaline conditions. A large excess of methacrylic acid was added to this product in the presence of p-toluenesulfonic acid for esterification to synthesize monomer 1 represented by Chemical Formula 3.

(Monomer 2)
4- (6-Hydroxyhexyloxy) benzoic acid was synthesized by heating p-hydroxybenzoic acid and 6-chloro-1-hexanol under alkaline conditions. A large excess of methacrylic acid was added to this product in the presence of p-toluenesulfonic acid for esterification to synthesize monomer 2 represented by Chemical Formula 4.

  Monomer 1 was dissolved in dioxane, AIBN was added as a reaction initiator, and polymerized at 70 ° C. for 24 hours to obtain Polymer 1. This polymer 1 exhibited liquid crystallinity.

  Monomer 1 and monomer 2 are dissolved in dioxane (molar ratio monomer 1: monomer 2 = 7: 3), AIBN is added as a reaction initiator, and polymerized at 70 ° C. for 24 hours. As a result, a photosensitive polymer 2 was obtained. This polymer 2 exhibited liquid crystallinity.

3 from Example 1, Ri embodiment der of the present invention to produce a retardation film, Example 4 from 11 Ru Reference Example der. In the following examples, a glass substrate was used as the base material. In the following examples, the optical properties of the film were measured using a birefringence measuring apparatus (AXOMETRICS / AxoScan), and the film thickness was measured using a film thickness meter (FILMETRICS / F20).
[Example 1]
Polymer 1 was dissolved in THF (tetrahydrofuran) to prepare a solution having a polymer concentration of 25% by weight. Using this solution, a coating film was formed on a substrate with a spin coater. The dried coating film had slightly negative C plate characteristics. Next, the substrate on which the coating film was formed was placed on a hot plate, the coating film was heated, and when the temperature reached 135 ° C., the substrate was taken out and cooled to prepare a sample. The prepared sample had enhanced characteristics of the negative C plate and had Re≈0 nm and Rth = 77.2 nm. The film thickness on the substrate was 2.3 μm.

[Example 2]
Polymer 1 was dissolved in a THF / diethyl carbonate mixed solution (blending weight ratio 67/8) to prepare a solution having a polymer concentration of 25% by weight. Using this solution, a film was formed on a substrate with a spin coater. The coated film after film formation had slightly negative C plate characteristics. Subsequently, after drying the coating film, the coating film was heated to 135 ° C. and then cooled in the same manner as in Example 1 to prepare a sample. The produced sample had enhanced characteristics of the negative C plate and had characteristics of Re≈0 nm and Rth = 105.8 nm. From this value, it was confirmed that the birefringence was enhanced from this value. The film thickness on the substrate was 2.3 μm.

[Example 3]
Polymer 2 was dissolved in a THF / diethyl carbonate mixed solution (blending weight ratio 67/8) to prepare a solution having a polymer concentration of 25% by weight. Using this solution, a coating film was formed on a substrate with a spin coater. The coating film after drying had slightly negative C plate characteristics. Next, the coating film was heated using the same means as in Example 1, and after the heating temperature reached 135 ° C., it was cooled to prepare a sample. The produced sample had enhanced characteristics of the negative C plate and had characteristics of Re≈0 nm and Rth = 127.1 nm. The film thickness on the substrate was 2.3 μm. This film was irradiated with 300 mJ / cm ² of ultraviolet light from a high pressure mercury lamp from the normal direction. When the change in solvent resistance was confirmed before and after irradiation, it was confirmed that the solvent resistance was improved after irradiation.

[Example 4]
Polymer 1 was dissolved in a THF / diethyl carbonate mixed solution (weight blending ratio 67/8) to prepare a solution having a polymer concentration of 25% by weight. Using this solution, a coating film was formed on a substrate with a spin coater. The film was irradiated with ultraviolet light from a high-pressure mercury lamp by polarization conversion using a Granteller prism from the normal direction (irradiation amount: 25 mJ / cm ² ). After irradiation, the coating film was heated using the same means as in Example 1, and after the temperature reached 135 ° C., it was cooled to prepare a sample. The produced sample had an Nz coefficient of 1.6, an Nz coefficient of 1 or more, and an in-plane retardation value of 60 nm. The film thickness on the substrate was 2.3 μm.

[Example 5]
Polymer 1 was dissolved in a THF / propyl carbonate mixed solution (formulation weight ratio 67/8) to prepare a solution having a polymer concentration of 25% by weight. Using this solution, a coating film was formed on a substrate with a spin coater. The film was irradiated with ultraviolet light from a high-pressure mercury lamp by polarization conversion using a Granteller prism from the normal direction (irradiation amount: 30 mJ / cm ² ). After the irradiation, using the same means as in Example 1, the coating film was heated and cooled when the temperature reached 135 ° C. to prepare a sample. The manufactured sample had an Nz coefficient = 1.7, an Nz coefficient of 1 or more, and an in-plane retardation value of 50 nm. The film thickness on the substrate was 2.3 μm.

[Example 6]
Polymer 2 was dissolved in a THF / diethyl carbonate mixed solution (formulation weight ratio 67/8) to prepare a solution having a polymer concentration of 25% by weight. Using this solution, a coating film was formed on a substrate with a spin coater. The film was irradiated with ultraviolet light from a high-pressure mercury lamp by polarization conversion using a Granteller prism from the normal direction (irradiation amount: 35 mJ / cm ² ). After the irradiation, using the same means as in Example 1, the coating film was heated and cooled when it reached 120 ° C. to prepare a sample. The produced sample had an Nz coefficient = 1.46, an Nz coefficient of 1 or more, and an in-plane retardation value of 80 nm. The film thickness of the film on the substrate was 2.5 μm.

[Example 7]
Polymer 1 was dissolved in a THF / DMSO mixed solution (formulation weight ratio 70/5) to prepare a solution having a polymer concentration of 25% by weight. Using this solution, a coating film was formed on a substrate with a spin coater (irradiation amount: 50 mJ / cm ² ). The film was irradiated with ultraviolet light from a high-pressure mercury lamp by polarization conversion using a Granteller prism from the normal direction (irradiation amount: 50 mJ / cm ² ). After the irradiation, using the same means as in Example 1, the coating film was heated and cooled when the temperature reached 135 ° C. to prepare a sample. The produced sample had characteristics with an Nz coefficient of 1 or more. The film thickness of the film on the substrate was 3 μm.

[Example 8]
Polymer 1 was dissolved in a THF / DMF mixed solution (formulation weight ratio 70/5) to prepare a solution having a polymer concentration of 25% by weight. Using this solution, a coating film was formed on a substrate with a spin coater. The film was irradiated with ultraviolet light from a high-pressure mercury lamp by polarization conversion using a Granteller prism from the normal direction (irradiation amount: 50 mJ / cm ² ). After the irradiation, using the same means as in Example 1, the coating film was heated, and cooled when the heating temperature reached 135 ° C. to prepare a sample. The produced sample had characteristics with an Nz coefficient of 1 or more. The film thickness of the film on the substrate was 3 μm.

[Example 9]
Polymer 1 was dissolved in a THF / propyl carbonate mixed solution (formulation weight ratio 67/8) to prepare a solution having a polymer concentration of 25% by weight. Using this solution, a coating film was formed on a substrate with a spin coater. This film was subjected to polarization conversion using ultraviolet light from a high-pressure mercury lamp using a Granteller prism and irradiated at an incident angle of 45 ° with respect to the coating surface (irradiation amount: 50 mJ / cm ² ). After irradiation, using the same means as in Example 1, the coating film was heated and when the heating temperature reached 135 ° C., it was cooled to prepare a sample. The optical characteristics of the prepared sample are the characteristics in which the biaxial refractive index ellipsoid (nx = 1.615, ny = 1.579, nz = 1.547) is inclined (fast axis inclination, inclination angle 17 °). The in-plane retardation value was 116.7 nm. The film thickness of the film on the substrate was 3 μm.

[Example 10]
Polymer 1 was dissolved in a THF / propyl carbonate mixed solution (formulation weight ratio 67/8) to prepare a solution having a polymer concentration of 25% by weight. Using this solution, a coating film was formed on a substrate with a spin coater. The film was irradiated with ultraviolet light from a high-pressure mercury lamp at an incident angle of 45 ° with respect to the coated surface without being converted to polarized light (irradiation amount: 50 mJ / cm ² ). After the irradiation, using the same means as in Example 1, the coating film was heated and cooled when the heating temperature reached 135 ° C. to prepare a sample. The optical characteristics of the fabricated sample are the characteristics in which the biaxial refractive index ellipsoid (nx = 1.545, ny = 1.570, nz = 1.626) is inclined (fast axis inclination, inclination angle 62 °). The in-plane retardation value was 109.5 nm. The film thickness of the film on the substrate was 3 μm.

[Example 11]
Polymer 1 was dissolved in a THF / propyl carbonate mixed solution (formulation weight ratio 67/8) to prepare a solution having a polymer concentration of 25% by weight. Using this solution, a coating film was formed on a substrate with a spin coater. On this film, ultraviolet light from a high-pressure mercury lamp is polarized using a Glanteller prism and incident on the coating surface from the normal direction, and ultraviolet light from the high-pressure mercury lamp is not polarized and remains unpolarized. Irradiation was performed at an incident angle of 60 ° to the coated surface. The intensity ratio of non-polarized light and polarized light was 1: 1, and the irradiation amount was 50 mJ / cm ² . After the irradiation, using the same means as in Example 1, the coating film was heated and cooled when the heating temperature reached 135 ° C. to prepare a sample. The optical characteristics of the prepared sample have a biaxial refractive index ellipsoid (nx = 1.551, ny = 1.541, nz = 1.588) tilted (fast axis tilt, tilt angle 22.8 °) The inner retardation value was 6.5 nm. The film thickness of the film on the substrate was 3 μm.

  According to the present invention, a thin optical element having desired optical characteristics such as optical characteristics of a negative C plate, biaxial optical characteristics, and optical characteristics shown by a biaxial refractive index ellipsoid inclined with respect to a non-surface Can be provided by a simple method. Such an optical element can be used for applications such as a depolarizing film of a liquid crystal display device.

  As described above, the preferred embodiments of the present invention have been described with reference to the drawings, but various additions, modifications, or deletions can be made without departing from the spirit of the present invention. Included in the range.

L: polarized ultraviolet light 1a: side chain 1b having high photosensitivity arrangement: side chain 1c having poor photosensitivity arrangement: side chain 2a having arrangement in the out-of-plane direction: side chain 2b having high photosensitivity arrangement after polarization exposure: Side chain 2c with poor photosensitivity after polarization exposure: Side chain arranged in the direction outside the exposure front surface after polarization exposure

Claims (4)

Applying a liquid crystalline polymer material containing a structural unit represented by chemical formula (1) to a substrate to form a coating film;
An orientation control step of orienting the liquid crystalline polymer material in the coating film,
The liquid crystalline polymer material is coated with a solvent containing an aprotic polar solvent, wherein the aprotic polar solvent is tetrahydrofuran (THF), diethyl carbonate, propyl carbonate, N, N- dimethylformamide ( DMF), and Ri least one der selected from dimethyl sulphoxide group consisting de (DMSO),
The alignment control step includes a heat treatment step for heating the coating film (except for the case where irradiation of polarized light is performed during or before the heat treatment step) , and has an optical characteristic of a negative C plate production how of the phase difference film.

(In the formula, t represents an integer of 0 to 3, and R represents one or more selected from hydrogen, an alkyl group, an alkyloxy group, and halogen.) A method for producing a retardation film according to claim 1, wherein the structural units represented by the chemical formula (2), method for producing a retardation film.

A method for producing a retardation film according to claim 1 or 2, wherein the liquid crystalline polymer material is characterized in that the photocrosslinkable is applied, method for producing a retardation film. A method for producing a retardation film according to any one of claims 1 to 3, after the orientation control step, further comprising a light irradiation step of performing irradiation of non-polarized light to the coating film A method for producing a retardation film.

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