WO2004005426A1

WO2004005426A1 - Light control device and its manufacturing method

Info

Publication number: WO2004005426A1
Application number: PCT/JP2003/008532
Authority: WO
Inventors: Takashi Shibuya; Masako Nagashima; Yasuhiro Ikeda
Original assignee: Asahi Glass Company, Limited
Priority date: 2002-07-05
Filing date: 2003-07-04
Publication date: 2004-01-15
Also published as: AU2003244209A1; JPWO2004005426A1

Abstract

A light control device in which when no voltage is applied, the light transmittance is small and the scattering is low, and when a voltage is applied, the light transmittance is large and the scattering is low. The light control device comprises a liquid crystal/polymer composite material containing a dichroic dye, a liquid crystal, and a polymer. When no voltage is applied, the light transmittance is 40% or less, and the scattering transmittance is 30% or less. When a voltage is applied, the light transmittance is 45% or more, and the scattering transmittance is 20% or less.

Description

Description Dimming element and method of manufacturing the same

The present invention relates to a light control device capable of controlling transmission and absorption of light by changing a voltage. Background technology>

There is an increasing demand for arbitrarily controlling the light transmittance of glass. In particular, for architectural or automotive glass, glass that can control the inflow of light from windows into the room is useful from the viewpoint of comfort and energy saving, and the transparency can be controlled from the viewpoint of privacy protection. Glass is useful.

Conventionally, the active dimming device has been electochromic device

It is called EC element. ) Was noticed. However, the EC element has a problem that the response speed is slow because the transmittance of light is controlled by a redox reaction.

Therefore, a voltage-driven liquid crystal light control device is attracting attention as an alternative to the EC device. The operation based on the following principle is known as a liquid crystal light control device. That is, when no voltage is applied, the light is reflected and scattered by the liquid crystal molecules, and appears to be milky white. On the other hand, when a voltage is applied, the liquid crystal is oriented in the direction of the external electric field. At this time, since the ordinary light refractive index (N.) of the liquid crystal and the refractive index (N _p ) of the polymer are close to each other, light scattering is reduced, and the element appears transparent. Since light is scattered when no voltage is applied to the liquid crystal light control device, the device becomes strongly opaque when a voltage cannot be applied at the time of failure or the like (for example, see Japanese Patent No. 31344522). See.) Therefore, when used as a dimming element for an automobile, there is a problem that a good view from the inside of the automobile cannot be secured at the time of failure. Invention disclosure> The present invention is intended to solve the above-mentioned problems. When no voltage is applied, light transmittance is small and scattering is small.On the other hand, when voltage is applied, light transmittance is large and scattering is small. An object is to obtain a light control element.

According to the present invention, a liquid crystal / polymer composite containing a dichroic dye, a liquid crystal, and a polymer is sandwiched between a pair of substrates with electrodes, at least one of which is transparent, and light transmission when no voltage is applied between the electrodes. The transmittance is 40% or less, the scattered transmittance (Td) is 30% or less, the light transmittance at the time of applying a voltage is 45% or more, and the scattered transmittance (Td) is 20% or less. Provided is a dimming element characterized by having a contrast with no application of 1.2 or more.

In the present invention, a mixture containing a dichroic dye, a liquid crystal, and a polymerizable compound is sandwiched between a pair of substrates with electrodes, at least one of which is transparent, and the polymerizable compound is polymerized at a temperature at which the mixture shows a liquid crystal phase. A method for manufacturing a light control element is provided. According to the present invention, a liquid crystal mixture containing a dichroic dye, a liquid crystal, and a polymerizable compound is sandwiched between a pair of substrates with electrodes, at least one of which is a transparent substrate, and the electrode is heated at a temperature at which the liquid crystal mixture exhibits a liquid crystal phase. The polymerizable compound is polymerized while applying a voltage in between, so that the light transmittance when no voltage is applied is 40% or less and the scattered transmittance (Td) is 30% or less, and the light The light control element has a transmittance of 45% or more, a scattered transmittance (Td) of 20% or less, and a contrast of 1.2 or more between when a voltage is applied and when no voltage is applied. A manufacturing method is provided.

FIG. 1 is a schematic cross-sectional view of an example of the light control device of the present invention.

Explanation of reference numerals

1 A, IB: Glass substrate

2 A, 2 B: Electrode film

3 A, 3 B: alignment film

4: Liquid crystal Z polymer composite

5: Sealant 6 A, 6 B: Electrode terminals

The liquid crystal Z polymer composite in the present invention is a composite containing a dichroic dye, a liquid crystal, and a polymer. The composite is formed by polymerizing a polymerizable compound at a temperature that indicates a liquid crystal phase in a mixture containing a dichroic dye, liquid crystal, and a polymerizable compound (hereinafter, also referred to as a mixture).

The light modulating device of the present invention is a device having a composite of a dichroic dye, a liquid crystal and a polymer.

A dichroic dye is a dye having a large difference in light absorption between the major axis direction and the minor axis direction of a molecule. In the light modulating device of the present invention, the absorption of the dichroic dye is increased and the light transmittance is reduced by the horizontal alignment with respect to the substrate when no voltage is applied. In addition, when a voltage is applied, the alignment state of the liquid crystal changes to a vertical alignment, and the dichroic dye is vertically aligned with the change, so that the absorption of the dichroic dye decreases and the transmittance of the element increases.

The dichroic dye in the present invention is not particularly limited, and various dichroic dyes can be used, but dichroic dyes having light fastness and durability, that is, anthraquinone compounds, azo compounds, etc. Is preferably used. The content of the dichroic dye in the present invention is preferably from 0.1 to 12% (based on mass. The% representing the mass ratio is the same hereinafter) based on the total amount of the liquid crystal and the polymer. 0.5 to 10% is more preferred. Further, as the dichroic dye in the present invention, one kind of dichroic dye may be used, or two or more kinds of dichroic dyes may be used.

The liquid crystal in the present invention is a composition comprising one or more liquid crystal compounds. The liquid crystal compound has a dielectric anisotropy (Δε) (Δε = (ε ||) — (ε 丄), where IIII is a dielectric constant in a molecular axis (long axis) direction, and ε 丄 is a molecule. The dielectric constant in the direction perpendicular to the axis.) May be a negative compound, a positive compound, or a compound having no dielectric anisotropy. In particular, it is preferable that the entire liquid crystal of the present invention has a positive dielectric anisotropy. If the dielectric anisotropy of the liquid crystal is positive, the liquid crystal is aligned horizontally. 3 008532

Four

In an optical element, when a voltage is applied, both the liquid crystal and the dichroic dye are vertically aligned, so that the light transmittance increases. In addition, the dielectric anisotropy of the liquid crystal in the present invention is preferably 1 or more, and particularly preferably 2 to 50. It is preferable that the dielectric anisotropy is 1 or more because the light control device can be driven at a low voltage.

The liquid crystal compound is not particularly limited, but in order to obtain a liquid crystal compound having a positive dielectric anisotropy, a compound in which a polar group such as a cyano group or a fluorine atom is bonded to the main chain in the molecular long axis direction. preferable.

Further, the refractive index anisotropy of the liquid crystal in the present invention (Δ η) (Δ η - η ε one eta, and however, n _e:... Extraordinary index, n: an ordinary refractive index) is 0 2 or less is preferred, and 0.15 or less is more preferred. When the refractive index anisotropy is 0.2 or less, scattering of light of the light control element upon application of a voltage is reduced, which is preferable. In order to reduce the refractive index anisotropy, it is preferable to use a liquid crystal containing at least one liquid crystal compound having a saturated carbon ring. The saturated carbocycle is a saturated cyclic compound composed of a carbon atom and a hydrogen atom, and is preferably a cyclohexane ring.

The amount of the liquid crystal in the present invention is preferably 50 to 98%, more preferably 55 to 95%, based on the total amount of the liquid crystal and the polymerizable compound. When the content is 50% or more, the light control device can be driven at a low voltage, which is preferable. When the content is 98% or less, the durability against repeated voltage application and non-application of voltage and the durability against mechanical external force are increased, and the reliability at high temperatures is further improved.

The liquid crystal in the present invention preferably contains a chiral agent to be a chiral nematic liquid crystal. Known chiral agents can be used in the present invention. The amount of the chiral agent is preferably from 0.1 to 30%, more preferably from 0.5 to 20%, based on the total amount of the liquid crystal and the chiral agent. When the content is 0.1% or more, the helical pitch of the chiral agent can be reduced, and the direction of the dichroic dye can be rotated for efficient use. Further, it is preferable that the content be 30% or less, since the influence on the liquid crystal temperature range can be reduced. As the chiral agent in the present invention, one kind of chiral agent may be used, or two or more kinds of chiral agents may be used. 2003/008532

Five

The polymer in the present invention refers to a compound having a polymerizable functional group, that is, two or more, preferably five or more, of the polymerizable compounds are reacted by reacting a part or all of the polymerizable functional groups of the polymerizable compound. Means what you do. Further, the liquid crystal / polymer composite of the present invention may contain an unreacted polymerizable compound.

The polymer in the present invention is preferably a polymer obtained by polymerizing a polymerizable compound. Examples of the polymerizable functional group include an acryloyl group, a methacryloyl group, a vinyl group, an acryl group, and an epoxy group. An acryloyl group and a methacryloyl group are preferable because of high reactivity.

More preferably, the polymerizable compound is a compound having a mesogenic structure. Having a mesogenic structure is preferable because the compatibility between the liquid crystal and the polymerizable compound is increased and the liquid crystal temperature range of the mixture is widened. As the mesogen structure, a structure having two or more divalent ring groups is preferable. More preferably, the structure has 2 to 5 pieces. The ring groups may be directly bonded to each other, or may be bonded via groups such as 1 O—, 1 OCO—, —COO—, —CH ₂ —, and —CH ₂ CH ₂ —. As the divalent ring group, a 1,4-phenylene group and a trans-1,4-cyclohexylene group are preferable. The hydrogen atom of the ring group may be substituted with an alkyl group having 1 or 2 carbon atoms, an alkoxy group having 1 or 2 carbon atoms, a cyano group, or a halogen atom. Further, as the mesogen structure, the structures represented by the formulas (1) and (2) are preferable.

a ^{1 to} ai ² each independently represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 or 2 carbon atoms, a cyano group, or a halogen atom. 2003/008532

6

One or more of the three 1,4-phenylene groups of formula (1) may be substituted with a 1,1,4-cyclohexylene group.

a ^{1 3} ~a ^{2 4:} each independently, a hydrogen atom, an alkyl group, having 1 or 2 alkoxy group having a carbon of 1 to 6 carbon atoms, Shiano group or a halogen atom.

One or more of the three 1,4-phenylene groups in Formula (2) may be substituted with a trans-1,4-cyclohexylene group.

The polymerizable compound in the present invention may be a compound having one polymerizable functional group or a compound having two or more polymerizable functional groups. When it has two or more polymerizable functional groups, they may be the same or different polymerizable functional groups. The polymerizable compound of the present invention is preferably a polymerizable compound having two or more polymerizable functional groups.

As the polymerizable compound, a compound represented by the following formula (3) is preferably exemplified. A ¹ (OR ¹ ) _n -OZO- (R ² O) _m -A ² · · · (3) A ¹ , A ² : each independently represents an acryloyl group, a methacryloyl group, a glycidyl group, or an aryl group Base

R ¹ and R ² each independently represent an alkylene group having 2 to 18 carbon atoms in which one or more of the hydrogen atoms may be substituted with an alkyl group.

Z: divalent group having a mesogenic structure

n and m: each independently an integer of 1 to 10.

The polymer in the present invention may be one obtained by polymerizing one kind of polymerizable compound, or one obtained by polymerizing two or more kinds of polymerizable compounds. Further, the polymer in the present invention is obtained by polymerizing only a polymerizable compound having a mesogenic structure, It is preferable to polymerize a polymerizable compound having a structure and a polymerizable compound having no mesogen structure.

The amount of the polymerizable compound is preferably 2 to 50%, more preferably 5 to 45%, based on the total amount of the liquid crystal and the polymerizable compound. A content of 2% or more is preferable because the durability of the light control element to repeated application and non-application of voltage and the durability to mechanical external force are increased. When the content is 50% or less, the driving voltage of the device can be reduced, and the temperature range in which the mixture of the liquid crystal and the polymerizable compound exhibits the liquid crystal phase is widened, which is preferable. It is preferable that the temperature range in which the liquid crystal phase is displayed is widened because the temperature range when polymerizing the compound can be widened.

The mixture of the liquid crystal and the polymerizable compound in the invention may contain a polymerization initiator for polymerizing the polymerizable compound. As the polymerization initiator, when photopolymerization is carried out, acetophenones, benzophenones, alkylaminobenzophenones, benzyls, benzoins, benzoin ethers, benzyldimethyl ketones, benzoylbenzoates, aryl ketone photopolymerization initiators such as α-acyroxime esters, sulfur-containing yellow photopolymerization initiators such as sulfides and thioxanthones, and acylphosphinoxide photopolymerization initiators such as acyldiarylphosphinoxide Is mentioned. One photopolymerization initiator may be used alone, or two or more photopolymerization initiators may be used in combination. When the mixture in the present invention contains a photopolymerization initiator, it can be used even if it further contains a photosensitizer such as an amine.

The photopolymerization initiator used in the present invention preferably absorbs light having a wavelength of from 300 to 400 nm. Specific examples of the photopolymerization initiator include the following compounds.

4-phenoxydichloroacetophenone, 4-t-butyldichloroacetophenone, 4-t-butyl-trichloroacetophenone, ethoxyacetophenone, 2-hydroxy-2-methyl-11-phenylpropane-1 1-one, 1- (4-isopropylphenyl) 1-2-hydroxy-2-methylpropane 1-one, 1- (4-dodecylphenyl) 1-2-methylpropane-1-one, 1 -{4- (2-Hydroxyethoxy) phenyl} 2-Hydroxy-2-methylolpropane 1-one, 1-phenylketone, 2-methyl-111 {4- (methylthio) phenyl} 2 Morpholinopropane One 1—on.

Benzyl, benzoin, benzoin methyl ether, benzoinethylenzyl dimethyl ketal, benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-phenylbenzophenone, hydroxybenzophenone, acrylated benzophenone, 3, 3 ' —Dimethyl-4-methoxybenzophenone, 3,3 ′, 4,4′-tetrakis (t-butylperoxycarbonyl) benzophenone, 9,10-phenanthrenequinone, camphorquinone, dibenzozoberonone, 2- Ethyl anthraquinone, 4,, 4 "-Jetyl isophthalophenone, α-asiloxime ester, methylphenyldalioxylate.

4 Benzenyl 4'-methyldiphenyl sulfide, thioxanthone, 2 monoclox thioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4,1 Getylthioxanthone, 2,4-diisopropylthioxanthone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide.

In the case of performing thermal polymerization, a polymerization initiator such as a peroxide or a curing agent such as an amine or an acid anhydride can be used depending on the type of the polymerization site. When heat polymerization is performed, the mixture in the present invention may further contain a curing aid such as an amine, if necessary.

The content of the polymerization initiator is preferably 20% or less with respect to the polymerizable compound, and when a high specific resistance is required for the polymer after polymerization, 0.01 to 10% is more preferable. It is good.

The mixture in the present invention may contain, if necessary, an antioxidant, a surfactant, a light stabilizer, a non-dichroic dye, a pigment, a chain transfer agent, a cross-linking agent, a defoaming agent, and the like. It can be included as long as the light control function is not impaired. The material of the substrate used for the light control device of the present invention is preferably glass or resin. As the resin, a transparent resin such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polycarbonate, polyarylate, polymethyl methacrylate, polyetherimide, or cellulose triacetate resin is preferable. At least one of the substrates is a transparent substrate, and the transparent substrate is preferably made of these materials. One of the two substrates may be a reflector such as a substrate on which an aluminum-dielectric multilayer film is formed.

It is preferable that a transparent electrode is laminated on the substrate in the present invention. Is a transparent electrode, ITO films and S n 0 ₂ film is preferable. Further, the substrate on which the transparent electrodes are laminated is preferably a transparent substrate.

The dimming device of the present invention has a pair of substrates with electrodes, at least one of which is a transparent substrate. At least one of the substrates is formed by laminating a transparent electrode on a transparent substrate.

The surface of the substrate with electrodes according to the present invention, which is in contact with the liquid crystal Z-polymer composite, is preferably, but not necessarily, treated for horizontal alignment of the liquid crystal. The treatment method is not particularly limited as long as the liquid crystal is horizontally oriented, and includes a known method. For example, a method of directly polishing the surface of the substrate, a method of rubbing after providing a resin thin film on the surface of the substrate, a method of providing an alignment agent on the surface of the substrate, and the like are exemplified.

In the present invention, the distance between the two substrates can be appropriately selected depending on the size of the spacer. The distance between the substrates is preferably from 2 to 50 m, and more preferably from 3 to 30 m. It is preferable that the distance between the substrates is 2 m or more, since the contrast is increased. Further, it is preferable that the distance between the substrates is 50 m or less, since the curing reaction proceeds easily.

Examples of the polymerization reaction in the present invention include a commonly used active energy ray polymerization reaction, thermal polymerization reaction and the like. In the case of the active energy ray polymerization reaction, a photopolymerization reaction is preferable, and a polymerization reaction by irradiation with ultraviolet rays is particularly preferable. The active energy rays used are not particularly limited, and may include ultraviolet rays, electron beams, and other active energy rays. 2003/008532

Ten

Although a straight line is mentioned, ultraviolet rays are preferred. Examples of ultraviolet light sources include xenon lamps, pulsed xenon lamps, low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, mercury-xenon (HgXe) lamps, chemical lamps, metal halide lamps, power-bon lamps, and tungsten lamps. .

In the case of a photopolymerization reaction, the polymerization reaction in the present invention is greatly affected by light irradiation intensity, irradiation temperature, and irradiation time. Particularly, the influence of the irradiation temperature is great. The light irradiation intensity, irradiation temperature, and irradiation time can be appropriately selected depending on the type of dichroic dye, liquid crystal, and polymerizable compound used, and the mixing ratio of each. The polymerization reaction is preferably carried out at a temperature at which the liquid crystal exhibits a liquid crystal phase by laminating the mixture on a substrate in a state where the mixture has been made into a homogeneous solution in advance. By polymerizing by this method, the liquid crystal Z polymer composite of the present invention is preferable because the liquid crystal is uniformly aligned with the substrate.

The polymerization reaction in the present invention may be performed in a state where a voltage is applied between the electrodes. When a liquid crystal having a positive dielectric anisotropy is used, when a voltage is applied, the liquid crystal is oriented perpendicular to the substrate, and the polymerizable compound is oriented perpendicular to the substrate along the liquid crystal. When the polymerization reaction proceeds in that state, the resulting polymer becomes a cured product maintaining the vertical orientation. Therefore, the scattered transmittance of the manufactured light control device when a voltage is applied can be significantly reduced.

The applied voltage during the polymerization in the present invention is preferably 0.5 V or more and 300 V or less, more preferably 1 V or more and 100 V or less. When the voltage is 0.5 V or more, the polymerizable compound can be vertically aligned, and when the voltage is 300 V or less, when the substrate spacing is non-uniform, short-circuiting at a portion where the spacing is narrow is reduced, which is preferable. The power supply characteristics of the voltage applied between the electrodes may be DC or AC, but AC is preferred. The frequency of the alternating current is not particularly limited, but is preferably from 20 Hz to 100 Hz.

In the manufacturing method of the present invention, a voltage may be preliminarily applied. Preliminary application means applying a voltage in advance before the polymerization reaction. The pre-applied voltage varies depending on the substrate interval, the temperature at the time of application, and the like, but is preferably 0.5 V or more and 300 V or less, more preferably 1 V or more and 100 V or less. The pre-applying time also depends on the substrate spacing, Although it varies depending on the temperature at the time, it is preferably 30 seconds or more and 1 hour or less. When the time is 30 seconds or longer, most of the polymerizable compound can be vertically aligned with respect to the substrate, which is preferable. The preliminary application time is preferably longer, but the upper limit is preferably 1 hour or less. The provision of the pre-application step is preferable because the polymerizable compound can be completely and uniformly vertically aligned, and as a result, a dimming element having a small scattering transmittance upon application of a voltage can be produced.

The method for manufacturing the light modulating element of the present invention is not particularly limited as long as it does not cause uneven injection or pinching, does not mix impurities, and can be laminated with a uniform thickness. Is mentioned. If the substrate is made of glass, prepare a glass substrate with two electrodes and perform orientation treatment on the electrode side of the substrate. A spacer such as a resin bead having a diameter of 2 to 50 / m is sprayed on the electrode side of one of the substrates, and the substrates are stacked so that the electrode sides face each other. The outer periphery of the stacked substrates is sealed with a sealant such as epoxy resin to produce a cell. Next, after enclosing the mixture in the present invention in a cell, the polymerizable compound is polymerized. As a method for enclosing the mixture, an injection port is provided in advance at one location of the sealant on the outer periphery of the substrate at the time of cell production, and the mixture is vacuum-injected from the injection port, and at least two locations of the sealant. Preferably, there is provided a method in which a cutout portion is provided, at least one of the cutout portions is immersed in the mixture, and suction is performed from the cutout portion not immersed.

When the substrate is made of resin, the method of fabricating the dimming element is as follows. A resin film substrate with two electrodes, which has been treated with a directing agent facing the electrode side, is sandwiched between two rolls, and at the same time, between the substrates. The mixture in which the spacer is uniformly dispersed is injected. Preferred examples include a method in which the polymerizable compound is continuously polymerized while maintaining a uniform substrate interval using the roll, and a method in which the polymerizable compound is manufactured in the same manner as a glass substrate.

As another manufacturing method of the light control device of the present invention, when the substrate is glass, a glass substrate with two electrodes is prepared, and the electrode side of the substrate is subjected to an alignment treatment as necessary. A spacer such as a resin bead having a diameter of 2 to 50 Am is sprayed on the electrode side of one of the substrates, and the substrates are stacked so that the electrode sides face each other. Said layered The outer periphery of the substrate is sealed with a sealant such as an epoxy resin to produce a cell. In the cell, a metal foil tape with a conductive adhesive is attached to both electrode surfaces, and the electrodes are taken out. Next, after enclosing the liquid crystal mixture in the present invention in a cell, a voltage is applied between the electrodes, and the polymerizable compound is polymerized while the voltage is applied. As a method for sealing the liquid crystal mixture, an injection port is provided in advance at one place of a sealant on the outer peripheral portion of the substrate at the time of cell production, and the liquid crystal mixture is vacuum-injected from the injection port. A preferred method is to provide a cutout at two or more locations, immerse one or more of the cutouts in the liquid crystal mixture, and suction from the non-immersed cutout.

The method for taking out the electrode from the electrode surface in the present invention is not particularly limited, and a known method can be used. For example, TAB or a conductive wire may be bonded to the electrode surface, a metal foil tape with a conductive adhesive may be attached to the electrode surface, or the conductive wire may be soldered to the electrode surface.

An example of a method for manufacturing a light control element when the substrate is made of resin will be described below. Prepare two resin film substrates with electrodes, with the electrodes facing each other and having been subjected to an orientation treatment as necessary. While the resin film substrate is sandwiched between two rolls, a liquid crystal mixture in which a spacer is uniformly dispersed is injected between the substrates. A method in which a power supply terminal is brought into contact with the electrode surface and a voltage is applied between the electrodes while the uniform substrate spacing is maintained by the rolls to continuously polymerize the polymerizable compound, and a method of manufacturing the glass. Preferably, a method of manufacturing by the same method as the substrate is used.

In the light control device of the present invention, in the case of a device having a planar shape or a device having a small area, a good light control device is obtained when the substrate is made of glass because the substrate has a higher light transmittance. Is preferred. However, when fabricating a non-planar element or a large-area element, that is, a dimming element for construction, automobiles, etc., it is preferable to use resin as the substrate material to obtain a lightweight and flexible element. Is preferred. The element of the resin substrate can be used in combination with other members, such as sandwiching it between laminated glasses. The light control device of the present invention is a normal mode light control device. That is, dimming in which light transmittance is low when no voltage is applied and light transmittance is high when voltage is applied Element.

The light modulating element of the present invention is a light modulating element in which a composite of a liquid crystal Z polymer is sandwiched between a pair of substrates with electrodes, at least one of which is transparent. FIG. 1 is a diagram showing an example of the light control device of the present invention.

The light control device of the present invention has a light transmittance of 40% or less when no voltage is applied, and a scattered transmittance (Td) of 30% or less. The lower limit of the light transmittance is preferably 3% or more, more preferably 5% or more. The lower limit of the scattered transmittance may be 0%.

In the light modulating device of the present invention, the light transmittance when voltage is applied is 45% or more, and the scattered transmittance (Td) is 20% or less. The upper limit of the light transmittance may be 100%. The lower limit of the scattered transmittance may be 0%.

The dimmer of the present invention has a contrast of 1.2 or more between when a voltage is applied and when no voltage is applied, and preferably 1.2 to 50.

Example

Hereinafter, the present invention will be described specifically with reference to examples, but the present invention is not limited to the examples. Examples 1 to 4 and 7 to 10 are Examples, and Examples 5 to 6 and 11 to 13 are Comparative Examples.

The transmittance, scattered transmittance, and contrast were measured by the following methods. First, a voltage of a rectangular wave having a frequency of 100 Hz was increased from 0 V to 60 V for 1 minute in the obtained dimming device. Next, it was dropped from 60 V to 0 V for 1 minute. After repeating this operation 10 times, the transmittance and the scattered transmittance were measured.

Measurement method of transmittance (Tp) and scattered transmittance (Td): For a dimming device where the voltage between the electrodes is 0 V and 60 V, the transmittance and the transmittance are measured using a haze meter according to the method described in JISR 321. The scattering transmittance was measured.

Contrast calculation method: Contrast = (Transmittance at voltage 60V) / (Transmittance at voltage 0V).

[Example 1]

Nematic liquid crystal with positive dielectric anisotropy P (Tc (isotropic phase transition temperature) = 109 ° C, Δ ε (dielectric anisotropy) = 3.35, Δη (refractive index anisotropy) = 0.09) is 80% of the total amount of the liquid crystal and polymerizable compound. The polymerizable compound is 20% based on the total amount of the liquid crystal and the polymerizable compound, the dichroic dye LSB278 (manufactured by Mitsubishi Chemical) is 5% based on the total amount of the liquid crystal and the polymerizable compound, and benzoin isopropyl ether is used. A mixture containing 0.60% of the total amount of the liquid crystal and the polymerizable compound was prepared.

Next, two glass substrates (100 mm long, 100 mm wide, 1. lmm thick, surface resistance 30 Ω square) with an ITO film formed were prepared. On the ITO surfaces of the two substrates, an imide-based aligning agent HL1110 was applied so as to have a solid content of 10 Onm, and was heated and cured at 180 for 30 minutes to perform a rubbing treatment. On the alignment agent layer of one board, and 30 Roh mm ² spraying resin beads having a diameter of 6 m (manufactured by Sekisui Fine Chemical Co.). On the substrate, uncured epoxy resin mixed with 6 μπι glass fiber having a width of lmm was printed on four sides (excluding the injection port) of the outer periphery of the substrate. The two substrates were placed so that the rubbing directions were antiparallel, and the ITO sides were placed inside, respectively, and the uncured epoxy resin was heated and cured at 60 for 5 minutes to produce a cell.

While maintaining the liquid crystal state of the mixture A with 6 O :, the mixture A was vacuum-injected into the cell from an injection port provided in the cell. Next, the cell was cooled to 45 ° C. Maintaining the liquid crystal state by keeping mixture A at 45 ° C, the main wavelength is 365! Using an HgXe lamp. ! ! ! ! UV intensity! ! ! The light control device was manufactured by irradiating for 10 minutes at / Ji !!! ² . The appearance of the fabricated light modulating device was transparent, similar to the cell before irradiation.

The measurement result of the transmittance of the obtained light control device was 38% at a voltage of 0 V and 66% at a voltage of 60 V. Td is 4% at 0V and 60% at 60V 10%. The contrast was 1.7. The element was transparent both when a voltage was applied and when no voltage was applied.

[Example 2]

A mixture B was prepared by adding 1% of resin beads (manufactured by Sekisui Fine Chemical Co., Ltd.) having a diameter of 6 zm to the mixture A and 5% of a chiral agent CN (cholesteryl nonanoate) to the liquid crystal.

Polyethylene terephthalate film with IT0 film formed on one side (thickness: 125 m, surface resistance: 300 Ω / Π) Two rolls of film held at 45 ° C with the ITO film facing each other Supplied. At the same time as the film was supplied to the roll, a mixture B in a liquid crystal state maintained at 60 ° C. was injected between the two substrates. The mixture B was laminated, that is, encapsulated between the substrates by passing the two substrates holding the mixture through the roll. Next, the substrate on which the mixture B is sealed, at 45 ° C with irradiation booth by dominant wavelength using a chemical lamp is a UV 352 eta m, irradiated with intensity 3mWZcm ² 10 min, the dimming element Was prepared.

The transmittance of the obtained dimming device was 25% at a voltage of 0 V and 64% at a voltage of 60 V. Td was 5% at 0V and 12% at 60V. The contrast was 2.6. Transparency was ensured both when voltage was applied and when voltage was not applied. In addition, a high-contrast element was obtained by adding a chiral agent.

[Example 3]

A mixture C was prepared in the same manner as in Example 2, except that the polymerizable compound was replaced with the compound of the formula (4) and the compound of the formula (5).

In the same manner as in Example 2, a light control device was produced. The transmittance of the obtained dimming device was 30% at a voltage of 0 V and 70% at a voltage of 60 V. Td was 0.5% at 0V and 0.7% at 60V. The contrast was 2.5. Transparency was ensured both when voltage was applied and when voltage was not applied.

[Example 4]

A mixture D was prepared in the same manner as in Example 2, except that the polymerizable compound was replaced with the compound of the formula (6) instead of the compound of the formula (4).

In the same manner as in Example 2, a light control device was produced.

The transmittance of the obtained light control device was 30% at a voltage of 0 V and 66% at a voltage of 60 V. Td was 0.4% at a voltage of 0V and 0.7% at a voltage of 60V. The contrast was 2.2. Transparency was ensured both when voltage was applied and when voltage was not applied.

[Example 5]

Same as Example 1 except that the nematic liquid crystal R is replaced by a nematic liquid crystal R with a negative dielectric anisotropy (Tc = 98 ° C, Δε = -5.6, Δη = 0.22). Thus, mixture 様 was prepared. Next, in the same manner as in Example 1, a light control device was manufactured. The transmittance of the obtained light control device was 67% at a voltage of 0 V and 2% at a voltage of 60 V. Td was 5% at 0V and 91% at 60V. Since a liquid crystal having a large Δη was used, light scattering was large when a voltage was applied, and the light control device had low transparency. In addition, since liquid crystal having a negative △ ε was used, the transmissivity was high when no voltage was applied, and the transmissivity was low when the voltage was applied.

[Example 6]

The photochromic element was prepared in the same manner as in Example 1 except that the mixture 時 at the time of UV irradiation was maintained at 25 ° C to be in a crystalline state instead of maintaining the liquid crystal state at 45 ° C. 8532

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A child was made.

The transmittance of the obtained light control device was 42% at a voltage of 0 V and 46% at a voltage of 60 V. Td was 50% at 0V and 55% at 60V. The contrast was 1.1. Because the polymer was polymerized in the crystalline state, light scattering was strong. (table 1)

[Example 7]

Commercially available nematic liquid crystal with positive dielectric anisotropy P (Tc (isotropic phase transition temperature) = 109 ° C, Δε (dielectric anisotropy) = 3.35, Δη (refractive index anisotropy) = 0.09) with respect to the total amount of the liquid crystal and the polymerizable compound, and 80% with respect to the total amount of the liquid crystal and the polymerizable compound. A mixture A containing 278 (manufactured by Mitsubishi Chemical Corporation) at 5% based on the total amount of the liquid crystal and the polymerizable compound and benzoin isopropyl ether at 0.60% based on the total amount of the liquid crystal and the polymerizable compound was prepared.

Next, two glass substrates (100 mm long, 100 mm wide, 1. lmm thick, surface resistance 30 Ω / port) on which the ITO film was formed were prepared. On the ITO surfaces of the two substrates, an imide-based aligning agent HL1110 was applied to a solid content of 10 Onm, and was heated and cured at 180 ° C for 30 minutes to perform a lapping treatment. On the alignment agent layer of one substrate, 30 beads /: mm ² of resin beads having a diameter of 6 (manufactured by Sekisui Fine Chemical Co., Ltd.) were sprayed. In addition, the substrate has four sides (injection portion) on the outer periphery of the substrate. except for. An uncured epoxy resin mixed with 6 mm glass fiber with a width of lmm was printed on the). The two substrates were placed so that the rubbing directions were antiparallel, and the ITO sides were placed inside, respectively. The uncured epoxy resin was heated and cured at 60 ° C for 5 minutes to produce a cell.

While maintaining the liquid crystal state of the mixture A at 60 ° C., the mixture A was vacuum-injected into the cell from an inlet provided in the cell. Next, the cell was cooled to 45 ^. While maintaining the liquid crystal state by maintaining the mixture A at 45 ° C, a metal foil tape with a conductive adhesive was attached to the electrode surfaces of both substrates of the cell, and a frequency of 50 Hz was applied to the metal foil tape. Preliminary application was performed by applying a voltage of 45 V for 5 minutes using an AC power supply. With the voltage still applied, a dimming element was fabricated by irradiating ultraviolet light having a main wavelength of 365 nm at an intensity of 3 mW / cm ² for 10 minutes using a HgXe lamp. The fabricated light modulating device was transparent in appearance, similar to the cell before irradiation.

The measurement result of the transmittance of the obtained light control device was 35% at a voltage of 0 V and 67% at a voltage of 60 V. Td was 9% at a voltage of 0 V and 4% at a voltage of 60 V. The contrast was 1.9. The element was transparent both when a voltage was applied and when no voltage was applied. In addition, by performing the polymerization reaction while applying a voltage, it was possible to reduce the scattered transmittance of the light control device, particularly when a voltage was applied.

[Example 8]

A mixture B was prepared by adding 1% of the resin beads having a diameter of 6 (manufactured by Sekisui Fine Chemical Co., Ltd.) to the mixture A and 1% of the chiral agent CN (cholesteryl nonanoate) to the liquid crystal.

Two rolls of a polyethylene terephthalate film (thickness: 125 nm, surface resistance: 300 Ω / port) with an ITO film formed on one side were prepared. The two rolls of the film were supplied to a roll maintained at 45 ° C. such that the ITO film sides faced each other. At the same time as the film was supplied to the roll, a liquid crystal mixture B maintained at 60 ° C. was injected between the two substrates. The two substrates holding the mixture are PT / JP2003 / 008532

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The mixture B was laminated or encapsulated between the substrates by passing through the substrate. Next, a terminal was brought into contact between the electrodes in which the mixture B was sealed, and a voltage of 45 V was applied for 5 minutes using an AC power supply with a frequency of 50 Hz to perform preliminary application. Irradiation was performed at a temperature of 45 ° C in a radiation booth at a temperature of 45 ° C with a voltage applied, using a chemical lamp for 10 minutes at an intensity of 3 mWZcm ² with ultraviolet light having a main wavelength of 352 nm. Next, after attaching a metal foil tape with conductive adhesive to the electrode surfaces of both film substrates, apply uncured epoxy resin to the outer periphery of the two films and heat cure at 60 ° C for 5 minutes. A dimming device was manufactured.

The transmittance of the obtained light control device was 23% at a voltage of 0 V and 66% at a voltage of 60 V. Td was 10% at 0V and 4% at 60V. The contrast was 2.9. Transparency was ensured both when voltage was applied and when voltage was not applied. By performing the polymerization reaction with the voltage applied, the scattered transmittance of the light control device, particularly when a voltage was applied, could be reduced. Also, by adding a chiral agent, a high-contrast element could be obtained.

[Example 9]

A mixture C was prepared in the same manner as in Example 8, except that the polymerizable compound was changed to the compound of the formula (5) instead of the compound of the formula (4), to thereby prepare a light control device.

The transmittance of the obtained light control device was 30% at a voltage of 0 V and 73% at a voltage of 60 V. Td was 5% at 0V and 3% at 60V. The contrast was 2.4. Transparency was secured both when a voltage was applied and when no voltage was applied. By performing the polymerization reaction with the voltage applied, it was possible to reduce the scattering transmittance of the light control device, particularly when the voltage was applied.

[Example 10]

A mixture D was prepared in the same manner as in Example 8, except that the polymerizable compound was replaced with the compound of the formula (6) instead of the compound of the formula (4), to thereby prepare a light control device.

The transmittance of the obtained dimming device was 29% at a voltage of 0 V and 67% at a voltage of 60 V. Td was 5% at 0V and 4% at 60V. The contrast was 2.3. Transparency was ensured both when voltage was applied and when voltage was not applied JP2003 / 008532

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. By performing the polymerization reaction with the voltage applied, it was possible to reduce the scattering transmittance of the light control device, particularly when the voltage was applied.

[Example 11]

A dimming element was prepared in the same manner as in Example 7, except that the mixture A was kept in a crystalline state by maintaining it at 25 ° C instead of maintaining the liquid crystal state at 45 ° C during UV irradiation. did.

The transmittance of the obtained light control device was 47% at a voltage of 0 V and 41% at a voltage of 60 V. Td was 51% at 0V and 40% at 60V. The contrast was 1.1. Because the polymer was polymerized in the crystalline state, light scattering was strong.

[Example 12]

Omitting preliminary application, except that the main wavelength using HgXe lamp without applying a voltage to irradiate the 3 65 nm of ultraviolet intensity 3mWZcm ² 10 minutes to prepare a to light control device in the same manner as Example 7 .

The measurement result of the transmittance of the obtained light control device was 38% at a voltage of 0 V and 66% at a voltage of 60 V. Td was 4% at 0V and 10% at 60V. The contrast was 1.7.

Since the polymerizable compound was polymerized without applying a voltage, Td at a voltage of 60 V was larger than that of the light control device manufactured in Example 7.

[Example 13]

Omitting preliminary application, except that the irradiation main wavelength using a chemical lamp without applying a voltage 3 52 nm of ultraviolet intensity 3 mW / cm ² 10 min, was dimming device in the same manner as Example 8 Produced.

The transmittance of the obtained light control device was 25% at a voltage of 0 V and 64% at a voltage of 60 V. Td was 5% at 0 V and 12% at 60 V. The contrast was 2.6.

Since the polymerizable compound was polymerized without applying a voltage, the Td at a voltage of 60 V was larger than that of the light control device manufactured in Example 8. Table 2

Industrial applicability>

The light control device of the present invention is a normal mode light control device. That is, it is possible to reduce the light transmittance and the scattering transmittance when no voltage is applied. For example, when the dimming element of the present invention is used for a glass for an automobile, the light transmittance can be kept in a small state when a voltage is not applied such as when the vehicle is parked, which is useful for crime prevention. In addition, even in the event of troubles such as breakdowns, it is possible to see through the vehicle, ensuring visibility from inside the vehicle.

Further, the light modulating element of the present invention has a large light transmittance and a small scattered transmittance when a voltage is applied, and has a small light transmittance and a small scattered transmittance when no voltage is applied. be able to. Accordingly, the light control device of the present invention can be used as a partition for a vehicle window glass (a windshield, a rear glass, a side glass, a sunglass, etc.), a window glass of an industrial vehicle such as a train or an aircraft, a shop window, an office or a house. It is useful for a wide range of applications, such as lighting control curtains, reflectors (for offices, windows, lighting, indirect lighting, etc.), interior materials, optical filters, optical shutters, and displays. For example, when the dimming device of the present invention is used for glass for automobiles, it is possible to adjust the amount of light entering the automobile by applying a voltage under sunlight and improve the visibility from the interior of the automobile. Can be secured. Also, at night When the outside of the vehicle is dark, it is possible to improve the visibility from inside the vehicle by applying a voltage.

Claims

The scope of the claims

1. A liquid crystal / polymer composite containing a dichroic dye, a liquid crystal, and a polymer is sandwiched between a pair of substrates with electrodes, at least one of which is transparent, and the transmittance of light when no voltage is applied between the electrodes. Is 40% or less and the scattered transmittance (Td) is 30% or less, the light transmittance at the time of applying voltage is 45% or more, and the scattered transmittance (Td) is 20% or less. A dimming element characterized in that the contrast with no voltage applied is 1.2 or more.

2. The light control device according to claim 1, wherein the liquid crystal has a dielectric anisotropy of 1 or more.

3. The light control device according to claim 1, wherein the liquid crystal has a refractive index anisotropy of 0.2 or less.

4. The light modulating device according to claim 1, wherein the polymer is a polymer having a mesogenic structure.

5. The light modulating element according to claim 1, wherein the liquid crystal / polymer composite contains a chiral agent.

6. A mixture containing a dichroic dye, a liquid crystal, and a polymerizable compound is sandwiched between a pair of substrates with electrodes, at least one of which is transparent, and the polymerizable compound is polymerized at a temperature at which the mixture exhibits a liquid crystal phase. The method for manufacturing a light control device according to claim 1, wherein

7. The production method according to claim 6, wherein the polymerizable compound is a compound having a polymerizable functional group and a mesogenic structure.

8. The production method according to claim 6, wherein the mixture contains a polymerization initiator.

9. A liquid crystal mixture containing a dichroic dye, liquid crystal, and a polymerizable compound is sandwiched between a pair of substrates with electrodes, at least one of which is a transparent substrate, and the liquid crystal mixture is interposed between the electrodes at a temperature at which the liquid crystal mixture shows a liquid crystal phase. The polymerizable compound is polymerized while applying a voltage, the light transmittance when no voltage is applied is 40% or less, the scattering transmittance (Td) is 30% or less, and the light transmittance when voltage is applied is A method for producing a dimming device, comprising: 45% or more, a scattering transmittance (Td) of 20% or less, and a contrast of 1.2 or more between when a voltage is applied and when no voltage is applied.

10. The method according to claim 9, wherein a voltage applied between the electrodes during polymerization of the polymerizable compound is 0.5 to 300 V.