JP2008046506A - Light control structure and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light control structure having high reflectance. <P>SOLUTION: In the light control structure provided with an optical function layer formed by alternately layering at least one translucent layer and at least one refractive index changing layer, the translucent layer includes an acrylic thiourethane resin. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a light control structure and a method for manufacturing the same. In particular, the present invention relates to an improvement for improving both transparency and light blocking characteristics in the visible light region.

  Glass parts (glazing materials) such as a vehicle windshield, rear glass, front side glass, rear side glass, sunroof, etc., ensure a passenger's field of view and give a feeling of opening.

  On the other hand, such a window material becomes a path of penetration of sunlight and heat into the vehicle interior of the vehicle, causing an increase in air conditioning load due to a rise in the temperature of the vehicle interior and discomfort due to a feeling of heat. Moreover, although a dark-colored window material is used from the surface of ensuring secrecy and anti-glare property, it is difficult to achieve both visibility. These are not only limited to vehicles, but are also a problem in buildings such as houses.

  In order to solve such a problem, in recent years, a dimming structure using an electrochromic (EC) element and a dimming structure using a liquid crystal element are being used. The former uses light absorption, and the latter uses light scattering to realize a dimming function.

  The EC element uses a material with a spectrum change caused by an electrochemical oxidation-reduction reaction such as tungsten oxide or Prussian blue, and the amount of solar energy transmitted can be controlled by absorbing light.

  A dimming structure using a liquid crystal element is made of a material whose arrangement changes with voltage, and is a material whose light transparency is changed by the arrangement of liquid crystals. As the liquid crystal element, a nematic liquid crystal element having a curved arrangement phase, a liquid crystal element obtained by a phase separation method, and the like are known. These elements operate on the following principle.

A liquid crystal element in which droplets of a liquid crystal substance are dispersed in a polymer is also known, but in such a liquid crystal element, liquid crystal is aligned along the curved surface of the polymer wall when no voltage is applied. As a result, the optical path is twisted, and the light is reflected and scattered at the interface between the polymer and the liquid crystal droplets, and appears milky white. On the other hand, when a voltage is applied to the liquid crystal element, the liquid crystals in the liquid crystal droplets are aligned in the electric field direction by an external electric field. At this time, by selecting so that the ordinary refractive index n _o of the liquid crystal and the refractive index n _{p of the} polymer coincide with each other, the light incident perpendicularly to the liquid crystal element surface is not reflected at the interface between the liquid crystal and the polymer. The liquid crystal element becomes transparent.

  Moreover, a method using a light control element utilizing light reflection is also conceivable. Utilizing the principle of multilayer interference film, light of a specific wavelength in incident light is reflected by a periodic change in refractive index, and has a multilayer structure of two or more kinds of substances having different refractive indexes. Is. When a dimming element using reflection is used, there is no re-radiation or scattering of solar energy into the room, and the temperature rise in the room and the feeling of heat can be effectively reduced. Further, since the strong reflected light and the fluoroscopic image from the room overlap, the secrecy is excellent and the view from the room is also ensured.

  When using a light control element utilizing such light reflection, it is necessary to produce an element that provides high reflection intensity in a wide wavelength region.

  For example, Patent Document 1 discloses a method of increasing the refractive index difference between layers by applying dynamic alignment control to liquid crystal molecules using an optical structure changing material, thereby improving the reflection intensity.

Further, in order to improve the reflection intensity of the light control element, a method of increasing the refractive index difference between layers by increasing the refractive index of the resin layer is conceivable. Methods for increasing the refractive index of the transparent resin include blending metal oxide fine particles into the resin used, dispersing heavy metals, using halogen atoms or sulfur atoms for molecules in the resin, etc. There is a method, and development of a high refractive index resin is being studied. In particular, it is known that a high refractive index can be obtained with a resin in which a part of the urethane resin is substituted with thiourethane. For example, Patent Document 2 discloses a high refractive index plastic using a sulfur-containing urethane resin. A lens is disclosed.
Japanese Patent Laid-Open No. 11-231135 JP 2001-56482 A

  However, the formation of the light control element as in Patent Document 1 requires a complicated manufacturing process. In addition, it is very difficult to form a thin film with high accuracy and stack it with a liquid crystal layer even with a resin having a high refractive index as described above, and a light control device using a resin as in Patent Document 2 has been reported. Absent. This invention is made | formed in view of such a problem, and it aims at providing the light control structure which shows high reflection intensity, and its manufacturing method.

  As a result of intensive studies, the inventors of the present invention have a light control structure including an optical function layer in which at least one light-transmitting layer and at least one refractive index change layer are alternately stacked. It has been found that the above object can be achieved by using an acrylic thiourethane resin layer having a high refractive index for the translucent layer.

  That is, the present invention is a light control structure including an optical function layer in which at least one light-transmitting layer and at least one refractive index change layer are alternately stacked, and the light-transmitting layer includes A dimming structure comprising an acrylic thiourethane resin.

  The present invention also includes a step of applying a mixture of a translucent material precursor containing a thiourethane acrylate and an acrylic resin precursor, a liquid crystal, and at least one polymerization initiator to a substrate; Irradiating the base material coated with the mixture with interference light to polymerize the translucent material precursor in layers to obtain an optical functional layer in which translucent layers and liquid crystal layers are alternately laminated, and It is a manufacturing method of the light control structure characterized by including.

  ADVANTAGE OF THE INVENTION According to this invention, the light control structure which gives a high reflectance can be provided without using a complicated manufacturing process. This light control structure is applicable not only to the glazing material for vehicles but also to the window material of an architect house.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, 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. Absent.

  In the drawings referred to in the following embodiments, the thickness, shape, and number of layers constituting the light control structure are exaggerated, but this facilitates understanding of the contents of the invention. It is to do.

(Structure of light control structure)
FIG. 1 is a diagram schematically showing a cross section of the light control structure of the present invention.

  As shown in FIG. 1, the light control structure 100 according to the present embodiment includes an optical function layer 110 in which translucent layers 111 and refractive index changing layers 112 are alternately stacked, and the optical function layer 110 from both sides. A pair of transparent electrode layers 120 each composed of a transparent electrode 121 and an electrode terminal 122, and a support substrate 130 that supports the transparent electrode layer 120 from the outside are provided. When an external field is applied to the transparent electrode 121, the optical functional layer 110 changes the refractive index of the refractive index changing layer 112 and exhibits a dimming function.

  In the light control structure of this invention, the translucent layer 111 contains acrylic thiourethane resin. As described later, a translucent layer having a high refractive index can be obtained by containing an acrylic thiourethane resin. Furthermore, the refractive index of the acrylic thiourethane resin can be controlled by adjusting the blending amount of the thiourethane acrylate as a raw material.

  The refractive index changing layer 112 is not particularly limited as long as it is formed of a material whose refractive index changes when an external field such as a voltage is applied and the refractive index changes when an external field is applied. As the external field, voltage, light, temperature, magnetic field, etc. can be used, but the electric field is most preferable as the external field because of the size of the external field necessary for refractive index change, the availability and manufacturing of the optical functional layer, It is preferable to use a material whose orientation is changed by application of voltage and whose refractive index is changed, for example, liquid crystal. Here, the orientation of the liquid crystal means that the liquid crystal is ordered in response to an electric field generated by applying a voltage, and the liquid crystal is arranged orthogonally or parallel to the electric field. As the liquid crystal, general liquid crystals such as nematic, smectic and cholesteric can be used, and any liquid crystal having different refractive index in different alignment states can be used.

  If the refractive index of the liquid crystal used near room temperature when a voltage is applied and the refractive index of the acrylic thiourethane resin that forms the translucent layer are almost the same, the refractive index of each layer is the same when the voltage is applied. It becomes transparent, and when a voltage is not applied, a refractive index difference is generated and a dimming function is exhibited. Or, when the refractive index of the liquid crystal to be used near the normal temperature when no voltage is applied and the refractive index of the acrylic thiourethane resin substantially match, the refractive index of each layer matches and becomes transparent when no voltage is applied, When a voltage is applied, a difference in refractive index is generated, and a dimming function is exhibited.

  The difference in refractive index between the translucent layer and the refractive index changing layer during visible light transmission is preferably 0.0005 or less, and more preferably 0.0001 or less. When the refractive index difference is 0.0005 or less, the visible light transmittance is excellent. Moreover, the refractive index difference between the translucent layer and the refractive index changing layer at the time of reflection is preferably 0.1 or more, more preferably 0.15 or more. When the refractive index difference is 0.1 or more, the light reflectivity is excellent.

  The support base material 130 supports the optical functional layer 110 and the transparent electrode layer 120. When the light control structure of the present invention is used as a glazing material for vehicles, the support base material 130 is preferably made of glass or a transparent resin. The support base material 130 may be made of the same material or different materials. When a transparent resin is used as the support substrate 130, a hard coat layer may be provided on the outermost surface in order to improve the scratch resistance of the surface. Moreover, when penetration resistance is calculated | required, such as a laminated glass for vehicles, a resin intermediate film may be further pinched | interposed between the optical function layer 110 and the support base material 130. FIG.

  As the transparent electrode 121, a material that transmits light in the visible light range and has conductivity is used, and a transparent conductive metal oxide thin film such as tin-doped indium oxide (ITO) or antimony-doped tin oxide (ATO) or A conductive polymer film is preferably used. In the case of using an ITO film, it is preferable to use a film thickness of about 100 to 150 nm, in which the electrical resistance can be made relatively small, and light absorption in the visible light region is hardly a problem. The voltage applied to the transparent electrode 121 may be a direct current or an alternating current, but an alternating current is desirable in terms of liquid crystal response and driving voltage.

  In the light control structure of the present invention, the thickness of each layer constituting the optical function layer 110 can be appropriately determined depending on the wavelength region where light control is desired, but is preferably in the range of 30 nm to 500 nm. As described above, the object of the present invention is to prevent heat and heat, to suppress vehicle cabin temperature, to prevent sunburn, to improve confidentiality, to improve antiglare property, etc., and to control the wavelength range affecting these, as described above. UV-A) to (visible range) to 2.5 μm (near infrared range). Conversely, light outside this wavelength range has a low intensity, and it is considered that there is no significant influence on the above purpose. If the thickness of the layer is 30 nm or more, a relatively long wavelength light source such as a visible light laser can be used as the interference light, and at the same time, the accuracy of the thickness of the layer can be ensured, and a multilayer structure can be formed. It becomes easy. If the thickness of the layer is 500 nm or less, the wavelength region that exhibits the dimming function becomes the visible light region that is the object of the present invention, and an increase in the thickness of the optical function layer that is more than necessary can be avoided. .

  Further, the number of layers stacked is appropriately determined depending on a desired optical function, that is, a wavelength region to be reflected, and can be determined as an arbitrary number of layers. Preferably, the number of laminated layers including the translucent layer and the refractive index changing layer is 61 to 121 layers.

  The dimming structure of the present invention preferably has a thickness of at least one of the light transmitting layer 211 and the refractive index changing layer 212 forming the optical function layer 210, as shown in FIG. The optical function layer gradually decreases from one endmost layer in the stacking direction toward the other endmost layer.

  As described above, when the thickness of each layer is constant, the reflection wavelength is uniquely determined by the combination of the thickness of the translucent layer 211, the thickness of the refractive index changing layer 212, and the refractive index of each layer. Is determined, and only a specific wavelength is reflected. For example, even if the thickness of the translucent layer and the thickness of the refractive index changing layer are different, if each layer has a constant thickness, only reflection at a specific wavelength can be obtained. By changing the thickness of at least one of the translucent layer and the refractive index changing layer in an inclined manner, a plurality of reflection wavelength peaks occur, and as a result, incident light is reflected in a wide wavelength region. Is possible.

  The range of change in the thickness of each layer in the light control structure of the present invention can be appropriately determined depending on the wavelength region where light control is desired, but the thickness of at least one of the translucent layer and the refractive index change layer is not limited. The ratio between the maximum value and the minimum value is preferably more than 1 and 20 or less. Here, the “ratio between the maximum value and the minimum value of the layer thickness” refers to a value obtained by dividing the maximum value of the layer thickness by the minimum value. When the ratio between the maximum value and the minimum value of the layer thickness is 1, only reflection at a specific wavelength occurs. More preferably, in consideration of reflecting light in a wide wavelength region, the ratio between the maximum value and the minimum value of the layer thickness is 1.5 or more. In consideration of suppressing the thickness of the optical functional layer and the ease of the manufacturing process, the ratio between the maximum value and the minimum value of the layer thickness is preferably 20 or less.

(Translucent layer)
The translucent layer of the present invention contains an acrylic thiourethane resin. Here, the acrylic thiourethane resin means a resin obtained by synthesis from thiourethane acrylate and an acrylic monomer. The acrylic thiourethane resin is not particularly limited as long as it is a resin that transmits light, and either a thermoplastic resin or a curable resin may be used. In particular, when the refractive index changing layer described later includes liquid crystal, a photocurable resin or a thermosetting resin is more preferable because of the ease of creating an optical functional layer, and a photocurable resin capable of simple and precise thickness control is preferable. Particularly preferred. Here, the photocurable resin means a resin that is cured (polymerized) by infrared rays, visible rays, ultraviolet rays, or electron beams. The form of polymerization may be, for example, vinyl polymerization, addition polymerization, condensation polymerization, cationic polymerization, anionic polymerization, living polymerization, etc., but preferably a substance that may cause deterioration or foaming of the optical functional layer. Vinyl polymerization, addition polymerization, condensation polymerization, cationic polymerization, anionic polymerization, and living polymerization are difficult to occur.

  The acrylic urethane resin that forms the translucent layer of the light control structure of the present invention is obtained by polymerizing thiourethane acrylate and a precursor of an acrylic resin. As a precursor of thiourethane acrylate and acrylic resin, a monomer or oligomer that is polymerized by light irradiation or a mixture of a monomer and an oligomer can be used. That is, any precursor having a general photopolymerizable group such as an acryloyl group, a methacryloyl group, or a vinyl group can be used. There may be a plurality of photopolymerizable groups in one molecule of the precursor.

  Examples of the monomer that becomes a precursor of the acrylic resin include 2-ethylhexyl acrylate, butyl ethyl acrylate, butoxy ethyl 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, isobornyl acrylate, isodecyl acrylate, lauryl acrylate, morpholine acrylate, Phenoxyethyl acrylate, phenoxydiethylene glycol acrylate, etc. Monofunctional acrylate compound, 2-ethylhexyl methacrylate, butylethyl 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, tetrahydrofurfuryl methacrylate, isobornyl methacrylate, isodecyl methacrylate, lauryl methacrylate, morpholine methacrylate, phenoxyethyl methacrylate, phenoxydiethylene glycol methacrylate Monofunctional methacrylate compounds such as dirate, 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, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, pentaerythritol triacrylate, ditrimethylolpropane tetraacrylate, dipentaerythritol hexaacrylate, dipentaerythritol monohydroxypentaacrylate, urethane acrylate Polyfunctional acrylate compounds such as oligomers, diethylene Glycol dimethacrylate, 1,4-butanediol dimethacrylate, 1,3-butylene glycol dimethacrylate, dicyclopentanyl dimethacrylate glycerol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, tetraethylene Polyfunctional methacrylate compounds such as glycol dimethacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetramethacrylate, pentaerythritol trimethacrylate, ditrimethylolpropane tetramethacrylate, dipentaerythritol hexamethacrylate, dipentaerythritol monohydroxypentamethacrylate, urethane methacrylate oligomer Can be mentioned. In addition, oligomers in which these monomers are partially polymerized, mixtures of monomers and oligomers can be used, and a plurality of these monomers can be used in combination.

  However, when a transparent layer is produced by polymerizing only the acrylic resin precursor as described above, the refractive index of the transparent layer is generally 1.47 to 1.51.

  In the light control structure of this invention, the acrylic thiourethane resin obtained by mix | blending and polymerizing thiourethane acrylate with the precursor of the above-mentioned acrylic resin is used as a translucent layer. Thiourethane resins are generally known to have a high refractive index, and some have a refractive index of 1.74. For this reason, an acrylic thiourethane resin having a high refractive index can be obtained by blending and polymerizing thiourethane acrylate into the above-mentioned acrylic resin precursor. At this time, the refractive index can be set to a certain value by controlling the blending amount of thiourethane acrylate.

  Hereinafter, thiourethane acrylate for producing an acrylic thiourethane resin having a high refractive index will be described. The thiourethane acrylate can be obtained by reacting thiourethane with an acrylate having a hydroxyl group in the molecule.

  Thiourethane can be synthesized from isothiocyanate and thiol by a conventional method.

  Examples of isothiocyanates that can be used include 1,2-diisothiocyanatoethane, 1,3-diisothiocyanatopropane, 1,4-diisothiocyanatobutane, and 1,6-diisothiocyanato. Xanthone, aliphatic isothiocyanates such as p-phenylene diisopropylidene diisothiocyanate, alicyclic isothiocyanates such as cyclohexane diisothiocyanate, 1,2-diisothiocyanatobenzene, 1,3-diisothiocyanate Oceanatobenzene, 1,4-diisothiocyanatobenzene, 2,4-diisothiocyanatotoluene, 2,5-diisothiocyanato-m-xylene, 4,4'-diisothiocyanato-1,1 '-Biphenyl, 1,1'-methylenebis (4-isothiocyanatobenzene), 1,1'-methylenebis (4-isothiosi Nato-2-methylbenzene), 1,1′-methylenebis (4-isothiocyanato-3-methylbenzene), 1,1 ′-(1,2-ethanediyl) bis (4-isothiocyanatobenzene), 4,4 '-Diisothiocyanatobenzophenone, 4,4'-diisothiocyanato-3,3'-dimethylbenzophenone, benzanilide-3,4'-diisothiocyanate, diphenyl ether-4,4'-diisothiocyanate, Aromatic isothiocyanates such as diphenylamine-4,4′-diisothiocyanate, or thiobis (3-isothiocyanatopropane), thiobis (2-isothiocyanatoethane), dithiobis (2-isothiocyanatoethane), etc. Sulfur-containing aliphatic isothiocyanate and 1-isothiocyanato-4-{(2-isothiocyanate Cyanato) sulfonyl} benzene, thiobis (4-isothiocyanatobenzene), sulfonylbis (4-isothiocyanatobenzene), sulfinylbis (4-isothiocyanatobenzene), dithiobis (4-isothiocyanatobenzene), 4- Isothiocyanato-1-{(4-isothiocyanatophenyl) sulfonyl} -2-methoxybenzene, 4-methyl-3-isothiocyanatobenzenesulfonyl-4′-isothiocyanatophenyl ester, 4-methyl-3-isothiocyana And sulfur-containing aromatic isothiocyanates such as tobenzenesulfonylanilide-3′-methyl-4′-isothiocyanate. Preferably, 1,2-diisothiocyanatoethane or 1,3-diisothiocyanatopropane is used.

  Examples of the thiol used include 1,2-ethanedithiol, 1,1-propanedithiol, 1,3-propanedithiol, 2,2-propanedithiol, 1,6-hexanedithiol, 1,2, Aliphatic polythiols such as 3-propanetrithiol, tetrakis (mercaptomethyl) methane, 1,1-cyclohexanedithiol, 1,2-cyclohexanedithiol, 2,2-dimethylpropane-1,3-dithiol, 1,2-di Mercaptobenzene, 1,3-dimercaptobenzene, 1,4-dimercaptobenzene, 1,2-bis (mercaptomethyl) benzene, 1,3-bis (mercaptomethyl) benzene, 1,4-bis (mercaptomethyl) Benzene, 1,2-bis (mercaptoethyl) benzene, 1,3-bis (merca) Aromatic polythiols such as (toethyl) benzene and 1,4-bis (mercaptoethyl) benzene, and the like, preferably 1,2-ethanedithiol, 1,1-propanedithiol, 1,3-propanedithiol are used. .

  The above-mentioned isothiocyanate and thiol can be reacted to synthesize thiourethane.

  Using the thiourethane synthesized as described above and the acrylate having a hydroxyl group in the molecule, the thioisocyanate at the end of the thiourethane and the hydroxyl group of the acrylate can be reacted to synthesize the thiourethane acrylate. . Here, as an acrylate which has a hydroxyl group in a molecule | numerator, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate etc. are mentioned, for example, Preferably it is 2-hydroxyethyl acrylate.

  The blending ratio of the above-mentioned acrylic monomer and thiourethane acrylate when preparing the acrylic thiourethane resin can be appropriately selected according to the type of compound used and the refractive index of the refractive index changing layer, but 1.612 or more. In order to produce a resin having a refractive index of, the compounding ratio is preferably 50:50 to 5:95 (acrylic: thiourethane), more preferably 15:85 to 5:95 by mass ratio. . When the blending ratio is in the above range, a resin having a high refractive index and excellent workability and transparency can be obtained.

  The refractive index of the acrylic thiourethane resin is measured with an Abbe refractometer (manufactured by ATAGO) based on a plastic refractive index measurement method (based on JIS K7142) by producing a film of acrylic thiourethane resin having a thickness of 1 to 3 mm. can do.

(Refractive index change layer)
The material such as liquid crystal forming the refractive index changing layer is uniformly compatible with the precursor (translucent material precursor) for forming the translucent layer from the side of the manufacturing method described later, and the transparent after polymerization. It is preferable that it is incompatible with the light-sensitive layer or difficult to be compatible.

  As the liquid crystal that can be used in the present invention, there are 2 to 4 cyclic compounds such as a benzene ring, a cyclohexane ring, a cyclohexene ring, and a hetero ring such as a pyrimidine ring, a dioxane ring, and a pyridine ring, an ester bond, and an acetylene bond. (Ethynylene group), ethane bond (ethylene group), ethylene bond (ethenylene group), azo bond, etc., and its end group and side substituent are cyano group, fluoro group, alkyl group, alkenyl group, For example, an azoxy group, biphenyl group, phenylcyclohexane group, phenyl ester group, cyclohexanecarboxylic acid phenyl ester group, phenyl pyrimidine group, phenyl dioxane group, and tolan group liquid crystal can be used. . Specifically, 4-pentyl-4′-cyanobiphenyl (5CB), 4-hexyl-4′-cyanobiphenyl (6CB), 4-hexyl-4′-cyanophenylpyridine, 4-hexyl-4′-propyl. And phenylcyclohexane, 4-methyl-4′-propyldicyclohexane, 4-hexyl-4′-methoxydicyclohexane, and the like. These liquid crystals can be used alone or as a mixture of a plurality of types of liquid crystals. In general, a mixture of two or more types of liquid crystals is often used to satisfy various requirements such as a temperature range in which the refractive index can be changed and the magnitude of the electric field. In the present specification, a single liquid crystal molecule and a mixture of two or more liquid crystals are collectively referred to as “liquid crystal”. Note that the refractive index changing layer does not need to be formed only of liquid crystal, and a resin or the like may be mixed to maintain the shape of the layer as long as the refractive index can be changed by an electric field.

(Production method)
Next, the manufacturing method of the light modulation structure which concerns on this invention is demonstrated in detail.

The method for producing a light control structure according to the present invention is based on a mixture of a translucent material precursor containing thiourethane acrylate and an acrylic resin precursor, liquid crystal, and at least one polymerization initiator. A light-transmitting layer and a liquid crystal layer are alternately formed by irradiating the base material coated with the mixture with interference light and polymerizing the light-transmitting material precursor in layers. And a step of obtaining an optical functional layer laminated on the substrate (second step).
In addition, after the second step, the optical functional layer is impregnated with the light transmissive material precursor, a mixed solution of the light transmissive material precursor and a solvent, or a solvent so that the optical functional layer is swollen. Step of gradually decreasing the thickness of at least one of the light-transmitting layer and the liquid crystal layer from the outermost layer on the side impregnated with the optical function layer toward the other outermost layer (first step). In addition, after the third step, non-interfering light or heat is applied to the swollen optical functional layer to further polymerize the precursor of the curable resin ( 4th process) can be included.

  The first step is a step of applying to the substrate a mixture in which a translucent material precursor including a precursor of thiourethane acrylate and an acrylic resin, a liquid crystal, and at least one polymerization initiator are mixed.

  The specific form and blending ratio of the precursors of thiourethane acrylate and acrylic resin are as described in the above-mentioned column of the light-transmitting layer of the present invention, and thus detailed description thereof is omitted here.

  When polymerizing the thiourethane acrylate and the precursor of the above-mentioned acrylic resin, at least one polymerization initiator is mixed and used. By using a polymerization initiator, the curing rate can be increased and the productivity can be improved. In addition, a photopolymerization initiation assistant that supplies protons and the like, a dye sensitizer that transfers excitation energy generated by absorbing light to the polymerization initiator, and the like may be added to the polymerization initiator. The polymerization initiator may be solid or liquid, but if the compatibility with the light transmissive material precursor is insufficient, interference light is scattered in the second step to be described later, making it difficult to form an optical functional layer. Therefore, it is desirable to be compatible with the translucent material precursor.

  The polymerization initiator can be appropriately selected based on the wavelength and intensity of the translucent material precursor and interference light (laser light) described later. Specifically, diketone, acetophenone, benzoin, benzophenone, thioxanthone, metallocene (such as titanocene) polymerization initiators such as diethoxyacetophenone, dimethoxyacetophenone, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl Ether, 4-phenylbenzophenone, 2-chlorothioxanthone, 2-methylthioxanthone, isopropylthioxanthone, Michler's ketone, and the like can be used.

  Furthermore, general photopolymerization initiation assistants such as methyldiethanolamine and 4-dimethylaminobenzoic acid can be used as the photopolymerization initiation assistant.

  The dye sensitizer may be any one as long as it is excited by light irradiation and transfers energy to the photopolymerization initiator. Examples of the dye sensitizer include a coumarin dye, a rhodamine dye, an oxazine dye, a carbocyanine dye, a styryl dye, a xanthene dye, a merocyanine dye, a rhodocyanine dye, a porphyrin dye, and an acridine dye. And pigments.

  Furthermore, in order to adjust the viscosity of the mixture, a general viscosity adjusting solvent may be added. The viscosity adjusting solvent is preferably selected from those having good compatibility with the mixture.

  The substrate is not particularly limited as long as it is smooth and reflects interference light. For example, a stretched resin film such as plate glass or polyethylene terephthalate can be used. Moreover, it can also be used as a base material which apply | coats either one of a pair of support base material which provided the transparent electrode layer mentioned above. In this case, after obtaining the optical functional layer, the dimming structure is completed simply by laminating the transparent electrode layer and the supporting substrate on the remaining one side. In order to apply the mixture to the substrate, a method that can apply the mixture with a uniform thickness, such as dipping, bar coating, spin coating, and printing, is desirable.

  In the second step, the translucent layer and the liquid crystal layer are formed by irradiating the base material coated with the mixture prepared in the first step with interference light and polymerizing the translucent material precursor in a layered manner. This is a process of obtaining optical functional layers laminated alternately.

  First, in order to polymerize and harden the translucent material precursor in the mixture prepared in the first step, it is irradiated with interference light. The coherent light uses two coherent light sources. At this time, the light from each coherent light source may intersect at the mixture surface, or the light from one coherent light source may be branched using a splitter, a mirror, or the like, and intersected at the mixture surface. The simplest and most accurate method is a method of irradiating light from the surface opposite to the substrate, that is, the surface coated with the mixture of the substrate, and causing interference with the reflected light from the surface. In the present specification, coherent light means laser light.

  The laser light used depends on conditions such as the wavelength of the laser light, the irradiation angle, and the refractive index of the mixture, but the portions where the laser light interference is strong and weak are formed at intervals of about several tens to several hundreds of nanometers. And in the part with strong interference, the said translucent material precursor hardens | cures and a phase separation with a liquid crystal arises. The separated liquid crystal is dispersed in the uncured translucent material precursor in the form of small droplets. As a result, it is possible to obtain a structure in which liquid crystal rich portions (liquid crystal layer) in which many liquid crystal droplets are present and resin rich portions (translucent layer) are alternately laminated in layers.

Perpendicular to the substrate surface (the angle between the normal surface and the normal line is 90 °, and the angle between the normal line and the incident light is the incident angle θ. In this case, the incident angle θ = 0 °) when irradiating a laser beam having a wavelength of lambda to the mixture of the refractive index n _m, the thickness d of the layer formed by the interference light is expressed by d = {λ / (2n m )} cosθ. When the incident angle θ = 0 °, cos θ = 1, and the layer thickness is d = λ / (2 _nm ).

The laser beam used can be appropriately selected depending on the desired layer thickness and the refractive index of the mixture used. For example, laser light such as Ar ⁺ laser (λ = 488 nm, 514.5 nm), He—Ne laser (λ = 633 nm), Kr ⁺ laser (λ = 647 nm), titanium sapphire laser (near 780 nm), or the like may be used. it can.

  From the above equation, when the irradiation angle θ is decreased, the layer thickness d is decreased, so that the layer thickness can be controlled by adjusting the irradiation angle. In addition, when performing the 3rd process mentioned later, in order to perform the impregnation and swelling in a 3rd process efficiently, a resin rich part (translucent layer) is not hardened | cured completely, but a crosslinking density is to some extent. It is preferable to adjust the intensity of the laser beam so as to decrease.

  The third step is a step for changing the thickness of at least one of the translucent layer and the liquid crystal layer in an inclined manner. In the optical functional layer obtained in the second step, the translucent layer and the liquid crystal layer have the same and uniform thickness. As a method for changing the thickness of at least one of the light transmitting layer and the liquid crystal layer, the following method can be used.

  When one endmost layer in the stacking direction of the optical functional layer obtained in the second step is impregnated with a translucent material precursor, a translucent material precursor / solvent mixed solution, or a solvent, impregnation is performed. An inclined structure is obtained in which the layers swell sequentially from the surface and the thickness of the layer gradually decreases from the outermost layer on the impregnated surface side toward the other outermost layer. When impregnated with a good solvent for the light-transmitting material precursor or the light-transmitting layer, the thickness changes mainly in the light-transmitting layer, impregnating with a good solvent for the liquid crystal layer and a poor solvent for the light-transmitting layer. In this case, the thickness change mainly occurs in the liquid crystal layer. What is necessary is just to implement this process suitably as needed.

  In the fourth step, non-interfering light or heat is applied to the entire surface of the optical functional layer to the swollen optical functional layer obtained in the third step, and a swollen resin-rich portion (translucent layer) and By completely curing the uncured translucent material precursor in the liquid crystal rich portion (liquid crystal layer), the optical functional layer obtained in the third step can be fixed. What is necessary is just to implement this process suitably as needed.

  The effect of this invention is demonstrated using a following example. However, the technical scope of the present invention is not limited to only the forms shown in the following examples.

(Example 1)
First, thiourethane was synthesized using 1,2-diisothiocyanatoethane and 1,2-ethanedithiol. From the synthesized thiourethane and 2-hydroxyethyl acrylate, thiourethane acrylate was synthesized by an ordinary method. The above thiourethane acrylate and methyl acrylate were mixed so that the weight ratio was 95: 5 (thiourethane acrylate: methyl acrylate), and this was used as a resin precursor.

Next, 4-pentyl-4′-cyanobiphenyl (ordinary refractive index 1.53, extraordinary refractive index 1.72) is used as the liquid crystal, and the liquid crystal and the resin precursor are in a weight ratio of 4: 6. (Liquid crystal: resin precursor), 3,3 ′, 4,4′-tetra (t-butylperoxycarbonyl) benzophenone as a polymerization initiator, and 3,3′carbonylbis ( 7-diethylaminocoumarin) was added to prepare a mixture. This mixture was applied onto a glass substrate using an applicator, irradiated with Ar ⁺ laser (λ = 488 nm) through an expander and a collimator, and the resin precursor was polymerized in layers to obtain an optical functional layer. After applying the mixed solution of the above-mentioned resin precursor and toluene to one endmost layer of the obtained optical functional layer and impregnating for about 30 seconds, the excess mixed solution on the surface is removed and a high pressure mercury lamp is used. The polymerization of the resin was completed. Finally, it was dried under reduced pressure to obtain a light control structure.

  When the cross section of the obtained light control structure is observed with a TEM, the light control structure obtained has a resin layer as the outermost layer on both sides, a constant thickness of the liquid crystal layer of about 80 nm, and a resin layer thickness of The multi-layer structure had a total number of 61 layers that gradually changed in one direction from about 80 nm to 150 nm.

(Example 2)
As the precursor, the same adjustment as in Example 1 was performed except that the above-described thiourethane acrylate and methyl acrylate were mixed and used so that the weight ratio was 90:10 (thiourethane acrylate: methyl acrylate). An optical structure was produced.

  In the obtained light control structure, the outermost layers on both sides are resin layers, the liquid crystal layer has a constant thickness of about 80 nm, and the thickness of the resin layer gradually changes in one direction from about 80 nm to 150 nm. It was a multilayer structure having 61 layers.

(Example 3)
As in Example 1, except that the thiourethane acrylate and methyl acrylate described above were mixed and used so that the weight ratio was 85:15 (thiourethane acrylate: methyl acrylate) as the resin precursor. A light control structure was produced.

  In the obtained light control structure, the outermost layers on both sides are resin layers, the liquid crystal layer has a constant thickness of about 80 nm, and the thickness of the resin layer gradually changes in one direction from about 80 nm to 150 nm. It was a multilayer structure having 61 layers.

Example 4
As in Example 1, except that the thiourethane acrylate and methyl acrylate described above were mixed and used so that the weight ratio was 55:45 (thiourethane acrylate: methyl acrylate) as the resin precursor. A light control structure was produced.

  In the obtained light control structure, the outermost layers on both sides are resin layers, the liquid crystal layer has a constant thickness of about 80 nm, and the thickness of the resin layer gradually changes in one direction from about 80 nm to 150 nm. It was a multilayer structure having 61 layers.

(Example 5)
As in Example 1, except that the thiourethane acrylate and methyl acrylate described above were mixed and used so that the weight ratio was 50:50 (thiourethane acrylate: methyl acrylate) as the resin precursor. A light control structure was produced.

  In the obtained light control structure, the outermost layers on both sides are resin layers, the liquid crystal layer has a constant thickness of about 80 nm, and the thickness of the resin layer gradually changes in one direction from about 80 nm to 150 nm. It was a multilayer structure having 61 layers.

(Evaluation of light control structure)
The light control structures of Examples 1 to 5 were sandwiched between glass plates with ITO electrodes, and the visible light reflectance when no voltage was applied was measured with a spectrophotometer. Next, a voltage of 200 V was applied to the ITO electrode, and the visible light transmittance was measured with a spectrophotometer. The visible light reflectance was measured with a regular reflectance at an incident angle of 5 ° according to JIS R3106, and corrected with visibility (visible light wavelength range: 380 to 780 nm). The results are shown in Table 1.

  Moreover, the spectrum of the visible light reflectance of the light modulation structure produced in Example 1 is shown in FIG.

(Refractive index of acrylic thiourethane resin)
The resin precursors used in Examples 1 to 5 were respectively polymerized to prepare acrylic thiourethane resins having a molecular weight of about 20,000 to 30,000 (resins 1 to 5). The refractive index of the acrylic thiourethane resin is measured with an Abbe refractometer (manufactured by ATAGO) based on a plastic refractive index measurement method (based on JIS K7142) by producing a film of acrylic thiourethane resin having a thickness of 1 to 3 mm. did. The results are shown in Table 2. The refractive index difference from the liquid crystal used in the examples is also shown.

  From Table 1 and FIG. 3, it can be seen that the dimming structure of the present invention exhibits high reflectance in a wide wavelength range. In addition, since the difference in refractive index between the light-transmitting layer and the liquid crystal layer when a voltage is applied is small, high visible light transmittance is exhibited. In particular, in Example 1 in which the blending ratio of thiourethane acrylate is high in the resin precursor, as shown in Table 2, the refractive index of the resin layer is particularly high, and the refractive index difference from the ordinary light refractive index of the liquid crystal layer is particularly large. In particular, an excellent reflection dimming function was recognized.

  The present invention is also applicable to window materials that require a dimming function, in particular, glazing materials for vehicles and window materials for building houses.

It is sectional drawing which shows typically one Embodiment of the light modulation structure of this invention. It is sectional drawing which shows typically one Embodiment of the light modulation structure of this invention. It is a spectrum of the visible light reflectance of the light control structure of Example 1.

Explanation of symbols

100, 200 light control structure,
110, 210 optical functional layer,
111, 211 translucent layer,
112, 212 refractive index changing layer,
120 transparent electrode layer,
121, 221 transparent electrode,
122 electrode terminals,
130, 230 Support base material.

Claims (9)

A dimming structure comprising an optical functional layer in which at least one light-transmitting layer and at least one refractive index change layer are alternately laminated,
The light-transmitting layer includes an acrylic thiourethane resin.   The thickness of at least one of the translucent layer and the refractive index changing layer is gradually decreased from one endmost layer in the stacking direction of the optical function layer toward the other endmost layer. The light control structure according to claim 1, wherein   The light control structure according to claim 1, wherein the refractive index changing layer includes at least one type of liquid crystal.   The optical function layer is sandwiched between a pair of transparent electrodes, and the refractive index of the refractive index changing layer is changed by applying a voltage to the transparent electrode. The light control structure of description.   The vehicle component using the light control structure of any one of Claims 1-4. Applying a mixture of a translucent material precursor containing a thiourethane acrylate and an acrylic resin precursor, a liquid crystal, and at least one polymerization initiator to a substrate;
Irradiating the base material coated with the mixture with interference light to polymerize the translucent material precursor in layers to obtain an optical functional layer in which translucent layers and liquid crystal layers are alternately laminated;
The manufacturing method of the light control structure characterized by including.   After the step of obtaining an optical functional layer in which the light transmissive layer and the liquid crystal layer are alternately laminated, the optical functional layer is mixed with the light transmissive material precursor, the light transmissive material precursor and a solvent, Alternatively, by impregnating with a solvent to make the optical functional layer swell, the thickness of at least one of the light transmitting layer and the liquid crystal layer is changed from the endmost layer on the side impregnated with the optical functional layer. The method for manufacturing a light control structure according to claim 6, further comprising a step of gradually decreasing toward the other endmost layer.   After the step of gradually decreasing the thickness of at least one of the translucent layer and the liquid crystal layer from the outermost layer on the side impregnated with the optical functional layer toward the other outermost layer, the swollen state The method for producing a light control structure according to claim 7, further comprising a step of applying non-interference light or heat to the optical functional layer to further polymerize the light transmissive material precursor.   The mixing ratio of the thiourethane acrylate in the translucent material precursor is 85% by mass or more and 95% by mass or less with respect to the total amount of the thiourethane and the acrylic resin precursor. Item 9. A method for producing a light control structure according to any one of Items 6 to 8.

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