JP2021026183A - Method for manufacturing dimming film and method for manufacturing display device - Google Patents

Abstract

To provide a method for manufacturing a dimming film, by which a degree of transparency in a transparent state in a dimming film can be improved, the dimming film showing changes in optical states between the transparent state and a non-transparent state.SOLUTION: A method for manufacturing a dimming film aims to manufacture a dimming film that shows an increase in the light scattering property when receiving ultraviolet light and a decrease in the light scattering property when receiving visible light. The method includes: a step of applying a composition comprising liquid crystal molecules, an optical active material comprising a photoisomerization material, a photopolymerizable monomer and a photopolymerization initiator on a substrate; a step of aligning the liquid crystal molecules included in the composition applied on the substrate; and a step of irradiating the composition with light at a wavelength different from the wavelength that promotes isomerization of the photoisomerization material, so as to cure the composition to obtain a cured product.SELECTED DRAWING: None

Description

The present invention relates to a method for manufacturing a light control film and a method for manufacturing a display device.

In recent years, a technique for displaying an image on transparent glass such as an automobile windshield or a building window glass has been developed.

In connection with this, there are known display devices having a screen whose optical state changes between a transmission state and a scattering state by applying a voltage, and a projector which projects image light onto the screen to display an image. In such a display device, a normally transparent screen can be temporarily made non-transparent to display an image on the screen.

However, in such a display device, control electrodes for applying a voltage are arranged inside the screen. Therefore, there is a problem that the control electrode has surface reflection and absorption, and the transparency of the screen in the transparent state is low.

On the other hand, in Patent Document 1, in order to improve the transparency of the screen in the transparent state, the light scattering property is increased by receiving ultraviolet light, and the light scattering property is decreased by receiving the first visible light. An image display body having a display function layer is provided, and a second visible light is projected onto the image display body whose light scattering property of the display function layer is increased by receiving ultraviolet light to display an image on the image display body. A display device for displaying is disclosed.

JP-A-2018-185511

The display device of Patent Document 1 can certainly improve the transparency of the image display body whose optical state changes between the transparent state and the non-transparent state in the transparent state, but further improves the transparency of the image display body in the transparent state. It is desired.

Therefore, an object of the present invention is to provide a method for producing a dimming film capable of improving the transparency in the transparent state in a dimming film whose optical state changes between a transparent state and a non-transparent state.

The present inventors have conducted diligent studies to solve the above problems. As a result, in the production of a light control film, it has been found that the transparency of the light control film in a transparent state can be improved by curing the composition containing the photopolymerizable monomer using light of a specific wavelength. Has been completed.

That is, according to one embodiment of the present invention, there is provided a method for producing a dimming film in which the light scattering property is increased by receiving ultraviolet light and the light scattering property is decreased by receiving visible light. , A step of applying a composition containing an optically active material containing a photoisomerizing material, a photopolymerizable monomer and a photopolymerization initiator to a substrate, and a step of orienting liquid crystal molecules contained in the composition applied to the substrate. The composition is characterized by having a step of irradiating the composition with light having a wavelength different from the wavelength that promotes isomerization of the photoisomerizing material and curing the composition to obtain a cured product. ..

According to the method for producing a light control film according to an embodiment of the present invention, in a light control film whose optical state changes between a transparent state and a non-transparent state, the transparency in the transparent state can be improved.

FIG. 1 is a perspective view showing a schematic configuration of a display device according to an embodiment of the present invention. FIG. 2A is a cross-sectional view showing a schematic configuration of an embodiment of an image display body. FIG. 2B is a cross-sectional view showing a schematic configuration of an embodiment of an image display body. FIG. 3 is a diagram for explaining the operation of the display device at the time of displaying an image. FIG. 4 is a diagram for explaining the operation of the display device when the image is not displayed. FIG. 5A is a cross-sectional view showing a schematic configuration of a transparent display function layer. FIG. 5B is a cross-sectional view showing a schematic configuration of a display functional layer in a non-transparent state. FIG. 6 is a graph showing the relationship between the integrated light amount of ultraviolet rays and the haze in the light control films produced in Examples and Comparative Examples.

One embodiment of the present invention is a method for producing a dimming film in which light scattering property is increased by receiving ultraviolet light and light scattering property is decreased by receiving visible light, and liquid crystal molecules and photoisomerization. A step of applying a composition containing an optically active material including a material, a photopolymerizable monomer, and a photopolymerization initiator to a substrate, a step of orienting liquid crystal molecules contained in the composition applied to the substrate, and the composition. A method for producing a light control film, which comprises a step of irradiating an object with light having a wavelength different from the wavelength that promotes isomerization of the photoisomerizing material and curing the composition to obtain a cured product. ..

According to the production method of this embodiment, by irradiating the composition with light having a wavelength different from the wavelength that promotes isomerization of the photoisomerizing material, it is possible to suppress the orientation of the liquid crystal molecules from being disturbed during polymerization. , The transparency in the transparent state can be improved.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the technical scope of the present invention should be determined based on the description of the scope of claims, and is not limited to the following embodiments. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicate description will be omitted. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation and may differ from the actual ratios.

Hereinafter, the display device according to the present invention will be described for convenience, and then the method for manufacturing the light control film according to the present invention will be described. First, as an example of the display device of the preferred embodiment of the present invention, an image display body, an ultraviolet light projecting unit, and two visible light projecting units (first visible light projecting unit and second visible light projecting unit) The display device having the above will be described, but the present invention is not limited to the following embodiments.

In the present specification, "X to Y" indicating a range means "X or more and Y or less". Unless otherwise specified, operations and physical properties are measured under the conditions of room temperature (20 to 25 ° C.) / relative humidity of 40 to 50% RH.

<Display device>
FIG. 1 is a perspective view showing a schematic configuration of a display device 10 according to an embodiment of the present invention. The display device 10 of the present embodiment includes an image display body 100, a first projector 200, a second projector 300, a third projector 400, and a control unit 500.

The image display body 100 is a thin plate-shaped member whose optical state changes between a transparent state and a non-transparent state, and is a front surface 100a facing the first to third projectors 200 to 400 and a side opposite to the front surface 100a. It has a back surface 100b. The image display body 100 changes from a transparent state to a non-transparent state by receiving ultraviolet light, and changes from a non-transparent state to a transparent state by receiving the first visible light. The image display body 100 is attached to, for example, the windshield of an automobile. A detailed description of the image display body 100 will be described later.

The first projector 200 is a projector that emits ultraviolet light, and is arranged so as to face the front surface 100a of the image display body 100. The first projector 200 emits ultraviolet light having a wavelength of, for example, 365 nm as an ultraviolet light projecting unit. The first projector 200 projects ultraviolet light onto the front surface 100a of the image display body 100 to change the projection region 100c of the ultraviolet light on the image display body 100 from a transparent state to a non-transparent state.

The second projector 300 is a projector that emits visible light having a specific wavelength, and is arranged so as to face the front surface 100a of the image display body 100. The second projector 300 emits first visible light having a wavelength of, for example, about 440 nm as the first visible light projecting unit. The second projector 300 projects the first visible light onto the image display body 100 in the non-transparent state, and changes the ultraviolet light projection region 100c on the image display body 100 from the non-transparent state to the transparent state.

The third projector 400 is a color projector and is arranged so as to face the front surface 100a of the image display body 100. The third projector 400 has, as the second visible light projecting unit, light of any one of three colors of blue (wavelength 450 nm), green (wavelength 532 nm), and red (wavelength 640 nm), or two or more colors. It emits second visible light, which is a combination of light. The third projector 400 projects the second visible light onto the non-transparent image display body 100 to display the image 600 on the image display body 100.

The control unit 500 controls the operations of the first to third projectors 200 to 400. The control unit 500 switches between light projection and non-light projection of the first and second projectors 200 and 300 while communicating with a higher-level control device (not shown). Further, the control unit 500 sends image information to the third projector 400 while communicating with a higher-level control device.

The first and third projectors 200 and 400 so that the image 600 displayed on the image display body 100 by the second visible light is included inside the ultraviolet light projection region 100c on the image display body 100. Projects ultraviolet light and second visible light, respectively. Further, the second projector 300 projects the first visible light so that the ultraviolet light projection region 100c is included in the first visible light projection region on the image display body 100.

Next, the image display body 100 of the display device 10 will be described in detail with reference to FIG. 2A.

FIG. 2A is a cross-sectional view showing a schematic configuration of the image display body 100. The image display body 100 of the present embodiment includes a display function layer 110, a dimming layer 120, and an ultraviolet light shielding layer 130. The display function layer 110 is arranged on the front surface 100a side of the image display body 100, and the ultraviolet light shielding layer 130 is arranged on the back surface 100b side of the image display body 100. The dimming layer 120 is arranged between the display function layer 110 and the ultraviolet light shielding layer 130.

The display function layer 110 is a film member whose optical state changes between a transparent state and a non-transparent state. The display function layer 110 has an optical property that the light scattering property is increased by receiving ultraviolet light to make it cloudy, and the light scattering property is lowered by receiving the first visible light to return to a transparent state. The display functional layer 110 of this embodiment is a light control film manufactured by the manufacturing method described later.

The dimming layer 120 is a transparent film member whose light absorption is increased by receiving ultraviolet light. The dimming layer 120 is made of a photochromic material, and has an optical property of increasing light absorption by receiving ultraviolet light and changing color from colorless to gray (or black). The dimming layer 120 has an optical property of not receiving ultraviolet light or receiving blue or yellow visible light to reduce light absorption and return from gray to colorless.

The ultraviolet light shielding layer 130 is a transparent film member that shields ultraviolet light. The ultraviolet light shielding layer 130 is made of a transparent resin containing an ultraviolet light reflecting agent or an ultraviolet light absorbing agent, and reflects or absorbs light in a wavelength region near the ultraviolet light to block it. The ultraviolet light shielding layer 130 is arranged on the back surface 100b side of the image display body 100, and prevents ultraviolet light from entering the display function layer 110 from the back surface 100b of the image display body 100.

As shown in FIG. 2B, the image display body 100 of the display device 10 may include a display function layer 110 and an ultraviolet light shielding layer 130. At this time, the display function layer 110 also serves as a dimming layer.

Next, the operation of the display device 10 for displaying an image on the image display body 100 will be described with reference to FIGS. 3 and 4.

FIG. 3 is a diagram for explaining the operation of the display device 10 when displaying an image, and FIG. 4 is a diagram for explaining the operation of the display device 10 when the image is not displayed.

As shown in FIG. 3, when displaying an image on the image display body 100, first, the first projector 200 projects ultraviolet light onto the front surface 100a of the image display body 100. When ultraviolet light is projected, the display function layer 110 becomes cloudy and the dimming layer 120 changes to gray, and the ultraviolet light projection region 100c on the image display body 100 changes from a transparent state to a non-transparent state. .. Then, the third projector 400 projects the second visible light onto the light projecting region 100c on the non-transparent image display body 100, and displays the image 600 on the image display body 100.

In addition, in order to prevent the image display body 100 from returning from the non-transparent state to the transparent state by receiving the second visible light while displaying the image 600 on the image display body 100, the first projector 200 Continues to project ultraviolet light onto the image display body 100. Specifically, in the first projector 200, for example, the ratio of isomerization of the photoisomerizing material by ultraviolet light (for example, the ratio of isomerization from the trans form to the cis form) is isomerized by the second visible light. Continue to emit ultraviolet light with an output that is greater than the ratio (for example, the ratio of isomerization from the cis form to the trans form).

On the other hand, as shown in FIG. 4, when the image is not displayed on the image display body 100 (when the image is erased), first, the first and third projectors 200 and 400 project ultraviolet light and second visible light. To stop each. Then, the second projector 300 projects the first visible light onto the front surface 100a of the image display body 100, and returns the ultraviolet light projection region 100c on the image display body 100 from the non-transparent state to the transparent state.

As described above, according to the display device 10 of the present embodiment, the transparent state / non-transparent state of the image display body 100 is switched by switching the projection / non-projection of the ultraviolet light and the first visible light. Then, the second visible light is projected onto the non-transparent image display body 100, and the image 600 is displayed on the non-transparent image display body 100. According to such a configuration, the normally transparent image display body 100 can be temporarily made non-transparent, and the image 600 can be displayed on the image display body 100.

<Manufacturing method of dimming film>
One embodiment of the present invention relates to a method for producing a dimming film in which light scattering property is increased by receiving ultraviolet light and light scattering property is decreased by receiving visible light. According to the method for producing a light control film according to this embodiment, a step of applying a composition containing a liquid crystal molecule, an optically active material containing a photoisomerizing material, a photopolymerizable monomer and a photopolymerization initiator to a substrate, and the above-mentioned step. The composition is subjected to a step of orienting liquid crystal molecules contained in the composition coated on the substrate and irradiating the composition with light having a wavelength different from the wavelength that promotes the isomerization of the photoisomerizing material. It has a step of curing to obtain a cured product. The light control film produced in this manner can be used, for example, as a display functional layer of the display device according to the above-described embodiment.

The light control film according to the present invention has an increased light scattering property by receiving ultraviolet light, and a reduced light scattering property by receiving visible light. Hereinafter, an example of the light control film according to the present invention will be described with reference to FIGS. 5A and 5B. In the following examples, as the isomerization material, a material whose structure changes from a transformer body to a cis body when it receives ultraviolet light and a structure changes from a cis body to a trans body when it receives visible light is used.

FIG. 5A is a cross-sectional view showing a schematic configuration of a transparent light control film (display functional layer 110), in which liquid crystal molecules 111 show homeotropic orientation. FIG. 5B is a cross-sectional view showing a schematic configuration of a non-transparent light control film (display functional layer 110). The photochromic film according to the present invention includes a cured product obtained by curing a composition containing a liquid crystal molecule, an optically active material containing a photoisomerizing material, a photopolymerizable monomer and a photopolymerization initiator. Therefore, the display functional layer 110 of the present embodiment includes the liquid crystal molecules 111 and the photoisomerizing material 112. The structure of the photoisomerizing material 112 changes from a trans body to a cis body when it receives ultraviolet light, and changes from a cis body to a trans body when it receives visible light. When the photoisomerizing material 112 changes to a cis form, it bends and disturbs the arrangement of the liquid crystal molecules 111. Therefore, ultraviolet light is cast on the display functional layer 110 in a homeotropic orientation state (see FIG. 5A) in which the liquid crystal molecules 111 are arranged substantially perpendicular to the thickness direction of the display functional layer and the liquid crystal phase is the nematic phase. When illuminated, the liquid crystal molecules 111 change to a focal conic state. At the same time, the arrangement of the liquid crystal molecules 111 is disturbed and changes to a scattered state (see FIG. 5B), and the light scattering property increases. On the other hand, if visible light is projected onto the display functional layer 110 in which the liquid crystal molecules 111 are in the scattered state (see FIG. 5B) and the liquid crystal molecules 111 are in the focal conic state, the liquid crystal molecules 111 are in the homeotropic orientation state (see FIG. 5A). ), The liquid crystal phase changes to the nematic phase, and the light scattering property decreases.

As shown in FIG. 5A, the light scattering property of the display functional layer 110 in which the liquid crystal molecules 111 are in the homeotropically oriented state is reduced. Therefore, if the visible light VL is projected onto the display function layer 110, the visible light VL passes through the display function layer 110. On the other hand, as shown in FIG. 5B, the display function layer 110 in which the liquid crystal molecules 111 are in a scattered state has an increased light scattering property and becomes a non-transparent state. Therefore, if the visible light VL is projected onto the display function layer 110, the visible light VL is diffusely reflected on the display function layer 110. Therefore, if the visible light VL is projected onto the display functional layer 110 in which the liquid crystal molecules 111 are scattered, an image can be displayed on the display functional layer 110.

(Step of applying a composition containing a liquid crystal molecule, an optically active material containing a photoisomerizing material, a photopolymerizable monomer and a photopolymerization initiator to a substrate)
In this step, a composition containing a liquid crystal molecule, an optically active material containing a photoisomerizing material, a photopolymerizable monomer and a photopolymerization initiator is applied to a substrate.

The liquid crystal molecule is not particularly limited, and a known nematic liquid crystal molecule can be used.

The liquid crystal molecule contains 2 to 4 cyclic compounds such as a benzene ring, a cyclohexane ring, a cyclohexene ring, a pyrimidine ring, a dioxane ring, and a pyridine ring, and has a single bond, an ester bond, an acetylene bond, an ethane bond, an ethylene bond, an azo bond, etc. It is a compound that is bonded and has a cyano group, a fluoro group, an alkyl group, an alkenyl group, and an alkoxy group at its ends. These compounds may be substituted with a cyano group, a fluoro group, an alkyl group, an alkenyl group, an alkoxy group and the like. That is, as liquid crystal molecules, biphenyl-based, biphenylcyclohexane-based, terphenyl-based, phenylcyclohexane-based, Schiff-based, azo-based, azoxy-based, benzoic acid ester-based, cyclohexylcarboxylic acid ester-based, pyrimidine-based, dioxane-based, Cyclohexylcyclohexaneester-based, cyclohexylethane-based, cyclohexene-based, fluorine-based and other liquid crystal molecules can be used.

Examples of liquid crystal molecules include 4-cyano-4'-ethylbiphenyl, 4-cyano-4'-pentylbiphenyl, 4-cyano-4'-propylbiphenyl, 4-cyano-4''-p-terphenyl, 4-Cyano-4'-propoxy-1,1'-biphenyl, 4-cyano-4'-(4-pentylcyclohexyl) biphenyl, 4-hexyl-4'-cyanophenylpyridine, 4-hexyl-4'-propyl Examples thereof include phenylcyclohexane, 4-methyl-4'-propyldicyclohexane, 4-hexyl-4'-methoxydicyclohexane and the like.

The liquid crystal molecules can be used alone or as a mixture of two or more.

The liquid crystal molecule can be used in both synthetic and commercial products. As a commercially available product, E44 (manufactured by Merck & Co., Ltd.) or the like can be used.

The optically active material includes a photoisomerizing material. The photoisomerizing material means a compound that absorbs light to cause cis-trans isomerization. The photoisomerizable material according to the present invention emits ultraviolet light even if it is a compound whose structure changes from a trans form to a cis form when it receives ultraviolet light, and changes its structure from a cis form to a trans form when it receives visible light. It may be a compound whose structure changes from a cis form to a trans form when it receives light, and changes its structure from a trans form to a cis form when it receives visible light.

In the present specification, "light having a wavelength different from the wavelength that promotes the isomerization of the photoisomerizing material" is "a wavelength different from the wavelength that promotes the isomerization of the photoisomerizing material from the trans form to the cis form". It means "light" or "light having a wavelength different from the wavelength that promotes the isomerization of the photoisomerizing material from the cis form to the trans form".

From the viewpoint of exerting the effects of the present invention, the photoisomerizing material according to the present invention preferably changes its structure from a trans form to a cis form when it receives ultraviolet light, and from a cis form to a trans form when it receives visible light. It is a compound whose structure changes to. When such a compound is used, "light having a wavelength different from the wavelength that promotes the isomerization of the photoisomerizing material" is "the wavelength that promotes the isomerization of the photoisomerizing material from the trans form to the cis form". Light of different wavelengths. "

Examples of the photoisomerizing material according to the present invention include an azobenzene compound, a chalcone derivative, a sulfoxide compound, a flugide compound, and a silicic acid compound.

The azobenzene compound includes a compound represented by the following chemical formula (1).

In the above chemical formula (1), R _{1 to} R ₁₀ are independently hydrogen atoms, substituted or unsubstituted alkyl groups, substituted or unsubstituted alkoxy groups, halogen groups, hydroxy groups, respectively. A group selected from the group consisting of carboxyl groups, ester groups (-COOR') and combinations thereof, where R'is a substituted or unsubstituted alkyl group and a substituted or unsubstituted alkoxy group. It is a group selected from the group consisting of.

Examples of alkyl groups include methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-. Linear alkyl groups such as decyl group, n-undecyl group, n-dodecyl group, n-tridecyl group, n-tetradecyl group, n-pentadecyl group, n-hexadecyl group; isopropyl group, isobutyl group, sec-butyl Group, tert-butyl group, isoamyl group, tert-pentyl group, neopentyl group, 1-methylpentyl group, 4-methyl-2-pentyl group, 3,3-dimethylbutyl group, 2-ethylbutyl group, 1-methylhexyl Group, tert-octyl group, 1-methylheptyl group, 2-ethylhexyl group, 2-propylpentyl group, 2,2-dimethylheptyl group, 2,6-dimethyl-4-heptyl group, 3,5,5-trimethyl Branched alkyl groups such as hexyl group, 1-methyldecyl group, 1-hexylheptyl group; can be mentioned.

Examples of alkoxy groups are methoxy group, ethoxy group, n-propoxy group, n-butoxy group, n-pentyloxy group, n-hexyloxy group, n-heptyloxy group, n-octyloxy group, n-nonyloxy group. Group, n-decyloxy group, n-undecyloxy group, n-dodecyloxy group, n-tridecyloxy group, n-tetradecyloxy group, n-pentadecyloxy group, n-hexadecyloxy group, etc. Alkoxy group in chain; isopropoxy group, tert-butoxy group, 1-methylpentyloxy group, 4-methyl-2-pentyloxy group, 3,3-dimethylbutyloxy group, 2-ethylbutyloxy group, 1- Methylhexyloxy group, tert-octyloxy group, 1-methylheptyloxy group, 2-ethylhexyloxy group, 2-propylpentyloxy group, 2,2-dimethylheptyloxy group, 2,6-dimethyl-4-heptyloxy group Group, branched alkoxy group such as 3,5,5-trimethylhexyloxy group, 1-methyldecyloxy group, 1-hexylheptyloxy group;

When the alkyl group and the alkoxy group have a substituent, the substituent to be introduced is not particularly limited. Specific examples thereof include a halogen group, an unsubstituted alkyl group, an unsubstituted alkoxy group and a combination thereof.

Halogen group refers to fluoro group (-F), chloro group (-Cl), bromo group (-Br) or iodine group (-I).

The azobenzene compound may be an isosorbide or isomannide esterified with the compound represented by the above chemical formula (1).

In a preferred embodiment, the azobenzene compound is selected from the compounds represented by the following chemical formulas (2) to (5).

Examples of chalcone derivatives include compounds represented by the following chemical formula (6).

Examples of the sulfoxide compound include a compound represented by the following chemical formula (7).

Examples of the flugide compound include a compound represented by the following chemical formula (8).

Examples of the cinnamic acid compound include compounds represented by the following chemical formulas (9) to (10).

The photoisomerization material preferably contains an azobenzene compound, more preferably contains compounds represented by chemical formulas (2) to (5), and more preferably has a chemical formula (5), from the viewpoint of a high photoisomerization reaction rate. Includes the compound represented by 5).

The photoisomerization material can be used alone or as a mixture of two or more.

The method for synthesizing the photoisomerized material is not particularly limited, and a conventionally known synthetic method can be applied. For example, the compounds represented by the chemical formulas (2) to (5) are described in Md. Z. Alam, T. et al. Yoshioka, T.M. Ogata, T.M. Nonaka, S.A. Kurihara, "Influence of Helix Power on Photoswitching Behavior of Chiral Azobenzene Compounds: Helix Applications, Technology, Technology, Technology, Technology" Euro. J. , 13, 2641-2647 (2007).

In a preferred embodiment, the optically active material further comprises a non-photoresponsive chiral compound in view of further improving the transparency of the light control film in the transparent state.

As the non-photoresponsive chiral compound, a compound having an optical rotation different from that of the photoisomerization material used can be used. By using the photoisomerizing material and the non-photoresponsive chiral compound in combination, the helical twisting power (HTP) between the photoisomerizing material and the non-photoresponsive chiral compound cancels each other. Can be done. That is, it is possible to further suppress the disorder of the arrangement of the liquid crystal molecules due to the twisting force of the photoisomerizing material of the trans form. Therefore, the transparency of the light control film in the transparent state can be further increased.

The spiral inducing force can be determined by the Cano wedge method.

Examples of non-photoresponsive chiral compounds include 4- [4- (hexyloxy) benzoyloxy] benzoic acid (R) -2-octyl, 4- [4- (hexyloxy) benzoyloxy] benzoic acid (S). -2-octyl, 4'-[(S) -2-methylbutyl] -1,1'-biphenyl-4-carbonitrile, bis [4- (trans-4-pentylcyclohexyl) benzoic acid] (R) -1 Examples thereof include −phenyl-1,2-ethanediyl and bis [4- (trans-4-pentylcyclohexyl) benzoic acid] (S) -1-phenyl-1,2-ethanediyl.

As the non-photoresponsive chiral compound, either a commercially available product or a synthetic product may be used. Examples of commercially available products include R-811, S-811, CB15, C15, S-1011 and R-1011 (manufactured by Merck & Co., Inc.).

When an azobenzene compound is used as the photoisomerization material, the non-photoresponsive chiral compound is 4- [4- (hexyloxy) benzoyloxy] benzoic acid (R) -2-octyl, 4'-[(S) -2. -Methylbutyl] -1,1'-biphenyl-4-carbonitrile and bis [4- (trans-4-pentylcyclohexyl) benzoic acid] (R) -1-phenyl-1,2-ethanediyl. It is preferably contained, and more preferably 4- [4- (hexyloxy) benzoyloxy] benzoic acid (R) -2-octyl is contained.

Examples of the photopolymerizable monomer include a monomer having one or more general photopolymerizable groups in the molecule such as an acryloyl group, a methacryloyl group, and a vinyl group.

Examples of photopolymerizable monomers include methyl acrylate, ethyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, butyl ethyl acrylate, butoxyethyl acrylate, 2-cyanoethyl acrylate, benzyl acrylate, cyclohexyl acrylate, 2-hydroxypropyl acrylate, 2-ethoxyethyl acrylate, N, N-diethylaminoethyl acrylate, N, N-dimethylaminoethyl acrylate, dicyclopentanyl acrylate, dicyclopentenyl acrylate, glycidyl acrylate, tetrahydrofurfuryl acrylate, isobonyl acrylate, isodecyl acrylate, Monofunctional acrylate compounds such as lauryl acrylate, morpholine acrylate, phenoxyethyl acrylate, phenoxydiethylene glycol acrylate; methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, 2-ethylhexyl methacrylate, butyl ethyl methacrylate, butoxyethyl methacrylate, 2-cyanoethyl methacrylate, benzyl. Methacrylate, Cyclohexyl methacrylate, 2-Hydroxypropyl methacrylate, 2-ethoxyethyl acrylate, N, N-diethylaminoethyl methacrylate, N, N-dimethylaminoethyl methacrylate, dicyclopentanyl methacrylate, dicyclopentenyl methacrylate, glycidyl methacrylate, tetrahydroflu Monofunctional methacrylate compounds such as frill methacrylate, isobonyl methacrylate, isodecyl methacrylate, lauryl methacrylate, morpholine methacrylate, phenoxyethyl methacrylate, and phenoxydiethylene glycol methacrylate; 4,4'-bis [6- (acryloyloxy) hexyloxy] biphenyl, diethylene glycol Diacrylate, 1,4-butanediol diacrylate, 1,3-butylene glycol diacrylate, dicyclopentanyl diacrylate, glycerol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, tetraethylene glycol Diacrylate, Trimethylol Propane Triacrylate, Pentaerythritol Tetraacrylate, Pentaerythritol Triacrylate, Ditrimethylol Propantetraa Polyfunctional acrylate compounds such as crylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate; 4,4'-bis [6- (methacryloyloxy) hexyloxy] biphenyl, diethylene glycol dimethacrylate, 1,4-butanediol Dimethacrylate, 1,3-butylene glycol dimethacrylate, dicyclopentyl dimethacrylateglycerol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, tetraethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetra Examples thereof include polyfunctional methacrylate compounds such as methacrylate, pentaerythritol trimethacrylate, ditrimethylolpropanetetramethacrylate, dipentaerythritol hexamethacrylate, and dipentaerythritol monohydroxypentamethacrylate.

The photopolymerizable monomer may be used alone or in combination of two or more.

The photopolymerization initiator is provided as long as it can generate radicals capable of initiating the polymerization of the photopolymerizable monomer by exposing it to light having a wavelength different from the wavelength that promotes the isomerization of the photoisomerizing material. There are no particular restrictions. The photopolymerization initiator can be appropriately selected depending on the photoisomerization material used.

From the viewpoint of curability, the photopolymerization initiator preferably has an absorbance at a wavelength of visible light, and more preferably has an absorbance at a wavelength included in the range of 400 to 500 nm. From the viewpoint of curability, the photopolymerization initiator preferably has an absorbance of 0.1% by mass, an optical path length of 1 cm, and a wavelength of 400 nm of 0.5 or more, and more preferably 1.0 or more. The upper limit of the absorbance is not particularly limited, and is, for example, 3.0 or less.

In the present specification, the absorbance of the photopolymerization initiator can be measured using a spectrophotometer (UV-2550, manufactured by Shimadzu Corporation) based on JIS K0115: 2004. As the measurement sample, a photopolymerization initiator dissolved in a solvent having no absorption at a wavelength of 400 to 500 nm (for example, acetonitrile, 1-methyl-2-pyrrolidone) at a concentration of 0.1% by mass is used.

Examples of photopolymerization initiators are phenylbis (2,4,6-trimethylbenzoyl) phosphine oxide, diphenyl (2,4,6-trimethylbenzoyl) phosphine oxide, bis (2,4-cyclopentadienyl) bis. [2,6-difluoro-3- (1-pyryl) phenyl] Titanium (IV), (benzene) tricarbonylchrome, 4,4'-bis (diethylamino) benzophenone, 4,4'-bis (dimethylamino) benzophenone , 2-Chlorothioxanthene-9-one, 4- (dimethylamino) benzophenone, phenanthrenquinone, thioxanthene-9-one and the like.

As the photopolymerization initiator, either a commercially available product or a synthetic product may be used. Examples of commercially available products include IRGACURE819, 784 (manufactured by IGM Resins BV), DAROCUR (registered trademark) TPO (manufactured by BASF), and the like.

The photopolymerization initiator may be used alone or in combination of two or more.

In the composition according to the present invention, the mass ratio of the liquid crystal molecule, the optically active material containing the photoisomerizing material, and the photopolymerizable monomer is, for example, 5 to 9: 1 to 4: 1, preferably 6 to 8: 1. ~ 3: 1.

In the composition according to the present invention, the content of the photopolymerization initiator is preferably 0.05 to 10% by mass, more preferably 0.1 to 7% by mass, based on the total mass of the composition. ..

The composition according to the present invention may contain other components as long as the effects of the present invention are not impaired. Examples of other components include dichroic dyes, photopolymerization initiators, dye sensitizers, solvents and the like.

Examples of dichroic pigments include acridine pigments, oxazine pigments, cyanine pigments, naphthalene pigments, anthraquinone pigments and the like.

Examples of the photopolymerization initiator include methyldiethanolamine, 4-dimethylaminobenzoic acid and the like.

The dye sensitizer is not particularly limited as long as it is a dye that is excited by light irradiation and can transfer energy to the photopolymerization initiator.

Examples of dye sensitizers include coumarin dyes, rhodamine dyes, oxazine dyes, carbocyanine dyes, styryl dyes, xanthene dyes, merocyanine dyes, rhodamine dyes, porphyrin dyes, and acridine dyes. And so on.

The solvent can be added to adjust the viscosity of the composition. The solvent is not particularly limited as long as it is compatible with the liquid crystal molecule, the optically active material, the photopolymerizable monomer and the photopolymerization initiator. Examples of the solvent include toluene, acetone, ethyl acetate and the like.

The method for preparing the composition is not particularly limited, and examples thereof include a method of mixing a liquid crystal molecule, an optically active material, a photopolymerizable monomer, a photopolymerization initiator and, if necessary, other components.

When a photoisomerized material and a non-photoresponsive chiral compound are used as the optically active material, the spiral inducing force between the trans- or cis photoisomerized material and the non-photoresponsive chiral compound cancels each other in advance. It is preferable to mix with other components after mixing at a mass ratio to be in a state. Thereby, in the step of orienting the liquid crystal molecules described later, it is possible to suppress the disorder of the arrangement of the liquid crystal molecules due to the twisting force of the trans- or cis-form photoisomerizing material.

The mixing conditions of the composition are not particularly limited, but it is preferable to mix each component in an environment in which the wavelength at which the polymerization initiator used has absorption is blocked. For example, the composition may be mixed in orange (wavelength 595-610 nm) light or in a brown bottle.

Examples of the base material used in this step include transparent base materials such as glass and resin.

Examples of glass include soda-lime glass, borosilicate glass, lead glass, quartz glass, non-alkali glass and the like.

Examples of resins include polymethylmethacrylate resin, polyacrylic resin, polyacrylonitrile resin, polycarbonate resin, polyester resin, polyether ether ketone resin, epoxy resin, norbornene resin, polysulfone resin, polyethersulfone resin, polyethersulfonate resin, Examples thereof include polyphenylene sulfide resin, polyimide resin, polyamide resin, polyolefin resin, polypropylene resin, polystyrene resin, polybutadiene resin, polymethylpentene, vinyl chloride resin and the like.

The shape of the base material may be a sheet shape or a film shape, or may be a cell (base material) using the above glass or resin.

The method for applying the above composition to the substrate is not particularly limited, and a conventionally known method can be used. When the base material is in the form of a sheet or a film, a dip method, a bar coating method, a spin coating method, a printing method and the like can be used. When the base material is a cell, a vacuum injection method, a drop injection method, or the like can be used.

(Step of aligning liquid crystal molecules contained in the composition applied to the base material)
In this step, the liquid crystal molecules contained in the composition applied to the base material in the above step are oriented.

The orientation of the liquid crystal molecules may be homogenous orientation (horizontal orientation) or homeotropic orientation (vertical orientation).

As a method for orienting the liquid crystal molecules, a conventionally known method can be used. For example, a method of applying an alignment film treatment to a base material, a method of attaching a transparent conductive film to the base material and applying a voltage, and the like can be mentioned. Examples of the alignment film treatment include physical treatment such as rubbing and mechanical surface treatment.

From the viewpoint of further improving the transparency of the transparent light control film, this step is preferably performed in an environment in which ultraviolet light and the wavelength at which the polymerization initiator used absorbs are blocked. For example, this step may be performed in orange (wavelength 595 to 610 nm) light.

(A step of irradiating the composition with light having a wavelength different from the wavelength that promotes isomerization of the photoisomerization material and curing the composition to obtain a cured product)
In this step, the composition coated on the base material and oriented with the liquid crystal molecules contained therein is irradiated with light having a wavelength different from the wavelength that promotes the isomerization of the photoisomerizing material. As a result, it is possible to suppress the isomerization of the trans or cis photoisomerized material into the cis or trans isomer during polymerization, and it is possible to suppress the disorder of the orientation of the liquid crystal molecules due to the isomerization of the photoisomerized material. .. Therefore, a cured product having higher transparency can be obtained in the transparent state. In addition, even if the transparent state and the non-transparent state are repeatedly changed, it is possible to suppress a decrease in the transparency of the light control film in the transparent state. That is, deterioration over time can be suppressed.

The wavelength of the light to be irradiated in this step can be appropriately selected depending on the optically active material including the photoisomerization material to be used and the photopolymerization initiator.

In one embodiment, from the viewpoint that the disorder of the orientation of the liquid crystal molecules can be further suppressed, it is preferable to irradiate visible light in the step of obtaining the cured product, and irradiate light having a wavelength in the range of 400 to 500 nm. And / or irradiate with light having an emission peak wavelength in the range of 430 to 460 nm. In particular, when the above-mentioned azobenzene compound is used as the photoisomerization material, the transparency of the cured product in the transparent state can be improved by irradiating with light having a wavelength in such a range.

In this step, when irradiating light, a filter that allows only a specific wavelength region to pass may be used, if necessary.

The amount of light to be irradiated is, for example, 1000 to 50,000 mJ / cm ² .

The temperature condition at the time of light irradiation is, for example, 10 to 40 ° C.

The orientation state of the liquid crystal molecules in the obtained cured product can be confirmed by using a polarizing microscope, a polarization analyzer, or the like.

The light control film according to the present invention may be in the form of a cured product (film-forming body) of the composition, or may be in the form of containing the above-mentioned base material and the cured product.

The thickness of the light control film is, for example, 50 to 500 μm.

<Manufacturing method of display device>
Another aspect of the present invention relates to a method for manufacturing a display device having an image display body, an ultraviolet light projecting unit, and at least one visible light projecting unit. According to the method for producing a display device according to this embodiment, the image display body contains a cured product of a composition containing a liquid crystal molecule, an optically active material containing a photoisomerizing material, a photopolymerizable monomer, and a photopolymerization initiator. The steps for producing the cured product include a step of applying the composition to a base material, a step of orienting liquid crystal molecules contained in the composition applied to the base material, and a step of photoisomerizing the composition. The present invention includes a step of irradiating light having a wavelength different from the wavelength that promotes the isomerization of the material to cure the composition to obtain a cured product.

According to the production method of this embodiment, by irradiating the composition with light having a wavelength different from the wavelength that promotes isomerization of the photoisomerizing material, it is possible to suppress the orientation of the liquid crystal molecules from being disturbed during polymerization. , The transparency in the transparent state can be improved.

Since each requirement constituting the method for manufacturing the display device of this embodiment is the same as the above-mentioned <display device> and <method for manufacturing the light control film>, the description thereof will be omitted.

<Use>
The use of the light control film and the display device according to the present invention is not particularly limited, but it is preferably applied to automobile glass, window glass of buildings, and the like. The light control film and the image display according to the present invention have high transparency in a transparent state, and can suppress deterioration with time. Therefore, the light control film and the display device according to the present invention are particularly advantageous when used for the windshield of an automobile.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples.

(Example 1)
Azobenzene compounds (compounds represented by the above chemical formula (5)) and 4- [4- (hexyloxy) benzoyloxy] benzoic acid (R) -2-octyl so that the spiral-inducing forces cancel each other out. (R-811, manufactured by Merck) was mixed at 10.2: 9.8 (mass ratio) to prepare an optically active material.

E44 (manufactured by Merck) as a liquid crystal molecule, the optically active material prepared above, 4,4'-bis [6- (acryloyloxy) hexyloxy] biphenyl as a photopolymerizable monomer, and IRGACURE 819 (IGM Resins) as a photopolymerization initiator. B.V.) was mixed at a mass ratio of 7: 2: 1: 0.1 to prepare a composition.

The glass substrate treated with the alignment film was laminated and fixed via a spacer so that the orientation direction was horizontal and the thickness of the cured product was 10 μm to prepare a cell (substrate). The prepared composition was injected into the cell.

The above step was performed in an environment where light having a wavelength of 500 nm or less was blocked.

Then, using an LED light source (M450LKP1, manufactured by THORLABS) as a light source, light having a wavelength of 440 nm was irradiated (10 mW / cm ² , 30 min), and the composition was cured to prepare a dimming film.

(Comparative Example 1)
A dimming film was prepared in the same manner as in Example 1 except that benzoin isopropyl ether was used as a photopolymerization initiator and an LED light source (M365LP1, manufactured by THORLABS) was used as a light source to irradiate light having a wavelength of 365 nm. did.

(Measurement of haze)
The light control films obtained in Example 1 and Comparative Example 1 were irradiated with UV light under the following conditions, and then with visible light (optical switching):
UV light: wavelength 365 nm, 10 mW / cm ² , 60 sec
Visible light: wavelength 440 nm, 60 mW / cm ² , 10 sec.

Using a haze meter (manufactured by Murakami Color Technology Laboratory Co., Ltd.), the haze of the transparent dimming film after irradiation with visible light was measured based on JIS K 7136: 2000.

The optical switching and haze measurements were repeated. The relationship between the integrated amount of ultraviolet rays and the haze is shown in FIG.

As shown in FIG. 6, in the examples, it can be seen that the deterioration of the transparency of the light control film can be suppressed by polymerizing with light having a wavelength of 440 nm. Further, since the haze remains low even if the integrated amount of ultraviolet rays increases, it can be seen that deterioration over time can be suppressed.

On the other hand, in the comparative example, by polymerizing with UV light, the azobenzene compound absorbs UV light during polymerization and isomerizes from the trans form to the cis form, so that the orientation of the liquid crystal is lowered (the orientation is disturbed). In addition to this, the polymerization of the photopolymerizable monomer does not proceed sufficiently because the UV light is absorbed by the azobenzene compound. For this reason, by repeating optical switching assuming actual use of the display device, the orientation of the liquid crystal molecules decreases during UV light irradiation, and at the same time, the polymerization process during the production of the light control film does not proceed sufficiently. Since the polymerization of the photopolymerizable monomer proceeds, it is considered that the increase in the orientation of the liquid crystal molecules (the decrease in the light scattering property of the light control film) is inhibited during the irradiation with visible light, and the transparency is reduced.

10 Display device,
100 image display body,
100a front,
100b back,
100c floodlight area,
110 Display function layer (dimming film),
111 liquid crystal molecules,
112 Photoisomerization material,
120 dimming layer,
130 UV light shielding layer,
200 1st projector (ultraviolet light projector),
300 2nd projector (1st visible light floodlight),
400 3rd projector (2nd visible light floodlight),
500 control unit,
600 images.

Claims (7)

A method for producing a light control film in which light scattering property is increased by receiving ultraviolet light and light scattering property is decreased by receiving visible light.
A step of applying a composition containing a liquid crystal molecule, an optically active material containing a photoisomerizing material, a photopolymerizable monomer and a photopolymerization initiator to a substrate, and
A step of orienting the liquid crystal molecules contained in the composition applied to the base material, and
A production method comprising a step of irradiating the composition with light having a wavelength different from the wavelength that promotes isomerization of the photoisomerization material to cure the composition to obtain a cured product. The production method according to claim 1, wherein in the step of obtaining the cured product, light having a wavelength included in the range of 400 to 500 nm is irradiated. The production method according to claim 1 or 2, wherein in the step of obtaining the cured product, light is irradiated having an emission peak wavelength in the range of 430 to 460 nm. The production method according to any one of claims 1 to 3, wherein the photopolymerization initiator has absorbance at a wavelength in the range of 400 to 500 nm. The production method according to any one of claims 1 to 4, wherein the photoisomerization material contains an azobenzene compound. The production method according to any one of claims 1 to 5, wherein the optically active material further contains a non-photoresponsive chiral compound. A method for manufacturing a display device having an image display body, an ultraviolet light projecting unit, and at least one visible light projecting unit.
The image display contains a cured product of a composition containing a liquid crystal molecule, an optically active material containing a photoisomerizing material, a photopolymerizable monomer and a photopolymerization initiator.
The step of producing the cured product is
The step of applying the composition to the substrate and
A step of orienting the liquid crystal molecules contained in the composition applied to the base material, and
A production method comprising a step of irradiating the composition with light having a wavelength different from the wavelength that promotes isomerization of the photoisomerization material to cure the composition to obtain a cured product.