Liquid crystal element and method for manufacturing the same

Abstract

Provided are a liquid crystal element and a method for manufacturing the same, which exhibit high transparency and light scattering properties, as well as excellent heat resistance, repeated drive resistance, and optical properties after bending, even without a liquid crystal alignment film on the substrate. The liquid crystal element comprises: a first substrate provided with a first electrode; a second substrate provided with a second electrode and disposed opposite the first substrate; and a liquid crystal layer disposed adjacent to the first and second substrates and formed by curing a liquid crystal composition containing a liquid crystal and a polymerizable compound. In the liquid crystal element, the liquid crystal layer is peeled from at least one of the first and second substrates, and the substrate from which the liquid crystal layer has been peeled is immersed in hexane at 23°C for 30 seconds and dried. When the surface of the substrate on the peeled side after drying is measured by X-ray photoelectron spectroscopy, the ratio of silicon atoms relative to the total amount of carbon atoms, oxygen atoms, and silicon atoms is determined to be 0.05% or more and 10% or less.

Description

Technical Field

[0001] The present disclosure relates to a liquid crystal element and a method for manufacturing the same.

[0002] Cross-references between related applications

[0003] This application is based on Japanese Patent Application No. 2020-89042 filed on May 21, 2020, the contents of which are incorporated herein by reference. Background Art

[0004] As a liquid crystal element, a polymer dispersed liquid crystal element is known in which a liquid crystal layer comprising a composite material of liquid crystal and polymer is arranged between a pair of film substrates having transparent electrodes formed on the surface. In recent years, it has been proposed to use a polymer dispersed liquid crystal element as a dimming element (for example, refer to Patent Document 1 or Patent Document 2). The dimming element of Patent Document 1 and Patent Document 2 changes transparency by switching between voltage application / no voltage application of the transparent electrode, thereby exhibiting a dimming function. In addition, research is underway to utilize the dimming function of the polymer dispersed liquid crystal element to give new functions to display windows or smart phones, televisions, monitors, buildings, furniture, etc. As polymer dispersed liquid crystals, polymer dispersed liquid crystals (PDLC) or polymer network liquid crystals (PNLC) are known.

[0005] As a polymer-dispersed liquid crystal element, it has previously been proposed to achieve a uniform and stable liquid crystal alignment state by injecting the constituent materials of a polymer / liquid crystal composite film together with a silane coupling agent into a cell and then irradiating the cell with light, without forming a liquid crystal alignment film on the surfaces of a pair of substrates (for example, see Patent Document 3). According to the technology of Patent Document 3, it is possible to simplify the manufacturing process by eliminating the need for forming a liquid crystal alignment film to control the orientation of the liquid crystal.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Laid-Open No. 2013-3319

[0009] Patent Document 2: Japanese Patent Application Laid-Open No. 2013-148744

[0010] Patent Document 3: Japanese Patent Application Laid-Open No. 2000-321562 Summary of the Invention

[0011] Problems to be solved by the invention

[0012] Liquid crystal elements manufactured using non-aligned film technology, which does not use a liquid crystal alignment film to control the orientation of liquid crystal molecules, have difficulty determining the initial orientation of the liquid crystal because they do not use an alignment film to control the initial orientation of the liquid crystal, and sometimes cannot achieve a fully transparent state. In addition, polymer-dispersed liquid crystal elements are envisioned for use outdoors or in high-temperature environments. Therefore, polymer-dispersed liquid crystal elements require high heat resistance, repeated drive resistance, and optical properties after bending.

[0013] The present disclosure has been made in view of the above-mentioned problems, and a main object thereof is to provide a liquid crystal element having high transparency and light scattering properties and excellent heat resistance, repeated drive resistance, and optical characteristics after bending, even without a liquid crystal alignment film.

[0014] Technical means to solve the problem

[0015] In order to solve the above-mentioned problems, the present disclosure adopts the following means.

[0016] <1> A liquid crystal element comprises: a first substrate provided with a first electrode; a second substrate provided with a second electrode and arranged opposite to the first substrate; and a liquid crystal layer arranged adjacent to the first substrate and the second substrate and formed by curing a liquid crystal composition containing a liquid crystal and a polymerizable compound, wherein the liquid crystal element does not have a liquid crystal alignment film, the liquid crystal layer is peeled off from at least one of the first substrate and the second substrate, the substrate from which the liquid crystal layer is peeled off is immersed in hexane at 23° C. for 30 seconds and dried, and when the surface of the substrate on the peeled side after drying is measured by X-ray photoelectron spectroscopy, the ratio of silicon atoms relative to the total amount of carbon atoms, oxygen atoms, and silicon atoms is greater than or equal to 0.05% and less than or equal to 10%.

[0017] <2> A method for manufacturing a liquid crystal element comprises: arranging a first substrate provided with a first electrode and a second substrate provided with a second electrode facing each other via a layer containing a liquid crystal composition containing a liquid crystal and a polymerizable compound to construct a liquid crystal cell; and irradiating the liquid crystal cell with light to cure the liquid crystal composition to form a liquid crystal layer.

[0018] The liquid crystal element does not have a liquid crystal alignment film, the liquid crystal layer is peeled off from at least one of the first substrate and the second substrate, the substrate from which the liquid crystal layer is peeled off is immersed in hexane at 23°C for 30 seconds and dried, and when the surface of the substrate on the peeled side after drying is measured by X-ray photoelectron spectroscopy, the proportion of silicon atoms relative to the total amount of carbon atoms, oxygen atoms and silicon atoms is greater than or equal to 0.05% and less than or equal to 10%.

[0019] <3> A method for manufacturing a liquid crystal element comprises: arranging a first substrate provided with a first electrode and a second substrate provided with a second electrode facing each other via a layer containing a liquid crystal composition containing a liquid crystal and a polymerizable compound to construct a liquid crystal cell; and irradiating the liquid crystal cell with light to cure the liquid crystal composition.

[0020] The liquid crystal element does not have a liquid crystal alignment film, and the liquid crystal element is heated to 50 mW / cm 2 Exposure to light with a wavelength of 313 nm for less than 150 seconds or at a rate of 150 mW / cm 2 The liquid crystal composition is cured by irradiating light with a wavelength of 365 nm for 150 seconds or less at the above irradiation amount.

[0021] Effects of the Invention

[0022] According to the above structure, even without a liquid crystal alignment film on the substrate, a liquid crystal element having high transparency and light scattering properties and excellent heat resistance, repeated drive resistance, and optical characteristics after bending can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 A diagram showing a schematic structure of a liquid crystal element.

[0024] Figure 2 A diagram illustrating the function of a liquid crystal element.

[0025] Explanation of symbols

[0026] 10: Liquid crystal element

[0027] 11: First substrate

[0028] 12: Second substrate

[0029] 13: Liquid crystal layer

[0030] 16, 17: Transparent electrodes DETAILED DESCRIPTION

[0031] Hereinafter, matters related to the aspects of the present disclosure will be described in detail.

[0032] (First embodiment)

[0033] <Liquid Crystal Element>

[0034] The liquid crystal element of this embodiment is a polymer dispersed liquid crystal element. Figure 1As shown, the liquid crystal element 10 includes a pair of substrates, including a first substrate 11 and a second substrate 12, and a liquid crystal layer 13 disposed between the first substrate 11 and the second substrate 12. The liquid crystal element 10 is a light-adjusting element that switches between a light-transmitting state and a light-blocking state by controlling the alignment of liquid crystal molecules 13b within a polymer network 13a formed in the liquid crystal layer 13 using an electric field.

[0035] The first substrate 11 and the second substrate 12 are transparent substrates made of glass or resin materials. Examples of the resin material constituting the substrates include silicon, polyethylene terephthalate, polybutylene terephthalate, polyethersulfone, polycarbonate, polypropylene, polyvinyl chloride, aromatic polyamide, polyamideimide, polyimide, triacetyl cellulose (TAC), and polymethyl methacrylate. The first substrate 11 and the second substrate 12 can be glass substrates, but plastic substrates are preferred for achieving a thinner and lighter liquid crystal element 10.

[0036] Transparent electrodes 16 and 17 are disposed on opposing surfaces of the first substrate 11 and the second substrate 12, respectively, forming an electrode pair. Transparent electrodes 16 and 17 are transparent conductive films, such as NESA film (a registered trademark of PPG, Inc., USA) containing tin oxide (SnO2), indium tin oxide (ITO) film containing indium oxide-tin oxide (In2O3-SnO2), or a film containing a carbon material. Transparent electrodes 16 and 17 may also have a predetermined pattern, such as a comb-like shape.

[0037] The liquid crystal layer 13 is formed by curing a liquid crystal composition containing liquid crystals and polymerizable compounds. The liquid crystal layer 13 is a polymer / liquid crystal composite material layer comprising a mixture of polymers and liquid crystal molecules 13b. Within the liquid crystal layer 13, a polymer network 13a is constructed by polymerizing the polymerizable compounds. In the liquid crystal element 10, no liquid crystal alignment film is formed on the first substrate 11 or the second substrate 12 to align the liquid crystal molecules 13b in the liquid crystal layer 13. Furthermore, the liquid crystal element 10 does not include polarizing plates on the outer surfaces of the first substrate 11 or the second substrate 12. Therefore, the liquid crystal element 10 exhibits excellent light absorption loss and high light utilization efficiency.

[0038] Figure 2 The figures are used to explain the function of the liquid crystal element 10. (a) shows a state where no voltage is applied between the transparent electrodes 16 and 17, and (b) shows a state where a voltage is applied between the transparent electrodes 16 and 17. The liquid crystal element 10 is an inverse polymer-dispersed liquid crystal element.

[0039] In the liquid crystal element 10, when no voltage is applied between the transparent electrodes 16 and 17, the long axis direction of the liquid crystal molecules 13b becomes perpendicular to the substrate surface, thereby allowing incident light to pass from one of the pair of substrates to the other, resulting in a transparent state. On the other hand, when a voltage is applied between the transparent electrodes 16 and 17, the orientation state of the liquid crystal molecules 13b changes, and the liquid crystal molecules 13b rotate in a direction parallel to the substrate surface. As a result, the incident light is scattered and becomes non-transparent. By switching between applying and not applying this voltage, the liquid crystal element 10 exhibits a dimming function. The liquid crystal element 10 is, for example, in the form of a film or a plate. Furthermore, the liquid crystal element 10 can also have a variable light transmittance according to the applied voltage.

[0040] In the liquid crystal element 10, the liquid crystal layer 13 is peeled off from at least one of the first substrate 11 and the second substrate 12, and the substrate from which the liquid crystal layer 13 is peeled off is immersed in hexane at 23°C for 30 seconds and dried. When the surface of the substrate on the peeled side after drying is measured by X-ray photoelectron spectroscopy (XPS), the ratio of silicon atoms to the total amount of carbon atoms, oxygen atoms and silicon atoms (hereinafter also referred to as "silicon surface coverage") is greater than 0.05% and less than 10%. If the silicon surface coverage is less than 0.05%, there is a tendency that the initial orientation of the liquid crystal cannot be determined, transparency cannot be fully ensured, or the improvement effect of heat resistance, repeated drive resistance, bending resistance and optical properties after bending cannot be fully obtained. From this point of view, the silicon surface coverage is preferably greater than 0.06%, more preferably greater than 0.08%, and further preferably greater than 0.10%. If the silicon surface coverage exceeds 10%, the repeated driving resistance, bending resistance, and optical properties after bending of the liquid crystal element 10 tend to deteriorate. Therefore, the silicon surface coverage is preferably 8.0% or less, more preferably 7.5% or less, and even more preferably 5.0% or less.

[0041] Furthermore, the silicon surface coverage can be adjusted by adjusting the content of the silicon-containing compound in the liquid crystal composition, the ratio of silicon atoms in the silicon-containing compound, the structure of the silicon-containing group (e.g., alkoxysilyl group) in the silicon-containing compound, etc. Surface analysis based on XPS can provide information about elements present at a depth of several nanometers from the surface. Therefore, based on the silicon surface coverage, the amount of silicon atoms (more specifically, the amount of silicon-containing compound) present in the boundary between the substrate and the liquid crystal layer 13 in the liquid crystal element 10 can be determined.

[0042] <Liquid Crystal Composition>

[0043] Next, the liquid crystal composition used to form the liquid crystal layer 13 of the liquid crystal element 10 will be described. The liquid crystal composition contains a liquid crystal and a polymerizable compound. In addition, the liquid crystal composition contains a silicon-containing compound.

[0044] (liquid crystal)

[0045] As liquid crystals, low molecular weight compounds having a liquid crystal phase such as nematic liquid crystals or smectic liquid crystals can be cited. The liquid crystal used is preferably a low molecular weight liquid crystal, more preferably a nematic liquid crystal. Furthermore, in this specification, the so-called "low molecular weight liquid crystal" refers to a liquid crystal compound that does not have a molecular weight distribution and has a molecular weight of 2000 or less. The low molecular weight liquid crystal is preferably a liquid crystal compound having a total of 2 to 10 of the following ring structures: at least one of a substituted or unsubstituted benzene ring and a cyclohexane ring. The number of rings possessed by the low molecular weight liquid crystal is more preferably 2 to 8, and further preferably 2 to 5.

[0046] In order to achieve improved optical properties in a liquid crystal element without a liquid crystal alignment film, the liquid crystal preferably contains at least one compound selected from the group consisting of a cyclohexyl cyanide group-containing liquid crystal and a tolanyl structure-containing liquid crystal (hereinafter also referred to as a "specific liquid crystal"). The specific liquid crystal preferably has negative dielectric anisotropy.

[0047] Specific examples of the specific liquid crystal include compounds represented by the following formula (1) and the like as liquid crystals containing a cyclohexylcyanide group, and compounds represented by the following formula (2) and the like as liquid crystals containing a tolan structure.

[0048] [Chemistry 1]

[0049]

[0050] (In formula (1) and formula (2), R 1 ~R 3 and Y 1 ~Y 4 are independently a halogen atom, a cyano group or a monovalent organic group having 1 to 10 carbon atoms, R 4 is a monovalent organic group having 1 to 10 carbon atoms; a1, a2, b1 and b2 are each independently an integer of 0 to 4)

[0051] In the above formula (1) and formula (2), R 1 ~R 4 The monovalent organic group is preferably a monovalent hydrocarbon group having 1 to 12 carbon atoms, a monovalent group formed by bonding a hydrocarbon group having 1 to 12 carbon atoms to an oxygen atom, or a group formed by replacing at least one hydrogen atom of a hydrocarbon group having 1 to 12 carbon atoms with a fluorine atom or a cyano group. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a fluorine atom is preferred.

[0052] As R1 ~R 4 From the viewpoint of further increasing the refractive index anisotropy, among these, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a fluoroalkyl group having 1 to 10 carbon atoms, a fluoroalkoxy group having 1 to 10 carbon atoms, an alkyl group containing a cyano group having 2 to 11 carbon atoms, or an alkoxy group containing a cyano group having 2 to 11 carbon atoms is preferred.

[0053] Y 1 ~Y 4 The monovalent organic group of Y is preferably an alkyl group or an alkoxy group having 1 to 3 carbon atoms. 1 ~Y 4 , preferably a fluorine atom, a cyano group, an alkyl group having 1 to 3 carbon atoms, or an alkoxy group having 1 to 3 carbon atoms.

[0054] More specifically, the compound represented by the formula (1) is a compound having a 1,2-diphenylacetylene skeleton. R1 and R 2 More preferably, it is an alkyl group or alkoxy group having 1 to 10 carbon atoms, and still more preferably, it is an alkyl group or alkoxy group having 1 to 8 carbon atoms. 1 It is preferably an alkyl group having 1 to 8 carbon atoms, R 2 An alkoxy group having 2 to 8 carbon atoms is preferred.

[0055] Y 1 and Y 2 It is preferably a halogen atom or a methyl group, and more preferably a fluorine atom.

[0056] a1 and b1 are preferably 0 to 2, more preferably 0 or 1. The compound represented by the formula (1) is preferably a neutral liquid crystal having a dielectric anisotropy of almost zero, or has a negative dielectric anisotropy.

[0057] The compound represented by the formula (2) is a compound having a biscyclohexylcyano skeleton. 3 and R 4 More preferably, it is an alkyl group or alkoxy group having 2 to 10 carbon atoms. 3 and R 4 The total number of carbon atoms in the moiety is preferably 4-15, more preferably 6-12.

[0058] Y 3 and Y 4 It is preferably a halogen atom or a methyl group, more preferably a fluorine atom or a methyl group. a2 and b2 are preferably 0 to 2, more preferably 0 or 1. The compound represented by formula (2) preferably has a negative dielectric anisotropy.

[0059] As specific examples of specific liquid crystals, the compound represented by formula (1) includes, for example, compounds represented by the following formulas (1-1) to (1-11), etc.; the compound represented by formula (2) includes, for example, compounds represented by the following formulas (2-1) to (2-10), etc. As specific liquid crystals, one type may be used alone, or two or more types may be used in combination.

[0060] [Chemistry 2]

[0061]

[0062] [Chemistry 3]

[0063]

[0064] The liquid crystal composition may further contain liquid crystals different from the specific liquid crystals (hereinafter also referred to as "other liquid crystals"). Examples of other liquid crystals include nematic liquid crystals and smectic liquid crystals, and among these, nematic liquid crystals are also preferred.

[0065] As specific examples of other liquid crystals, liquid crystal compounds with positive dielectric anisotropy include: biphenyl liquid crystals, phenylcyclohexane liquid crystals, ester liquid crystals, terphenyl liquid crystals, biphenylcyclohexane liquid crystals, pyrimidine liquid crystals, dioxane liquid crystals, bicyclooctane liquid crystals, cubane liquid crystals, etc.; liquid crystal compounds with negative dielectric anisotropy include: dicyanobenzene liquid crystals, pyridazine liquid crystals, Schiff base liquid crystals, azoxy liquid crystals, biphenyl liquid crystals, phenylcyclohexane liquid crystals, terphenyl liquid crystals, dicyanophenyl ester liquid crystals, alkenyl liquid crystals, etc. Furthermore, nematic liquid crystals can also be added as liquid crystals, such as cholesteryl chloride, cholesteryl nonanoate, and cholesteryl carbonate; or ferroelectric liquid crystals such as p-decyloxybenzylidene-p-amino-2-methylbutylcinnamate. Other liquid crystals can be used singly or as a mixture of two or more, depending on physical properties such as dielectric anisotropy and birefringence. The other liquid crystals preferably have negative dielectric anisotropy, and more preferably are negative-type liquid crystals with negative dielectric anisotropy.

[0066] Relative to the specific liquid crystal in liquid crystal composition and the total amount of other liquid crystals, the containing ratio of specific liquid crystal is preferably more than 1 mass %, more preferably more than 5 mass %, and then preferably more than 10 mass %. In addition, relative to the specific liquid crystal in liquid crystal composition and the total amount of other liquid crystals, the containing ratio of specific liquid crystal is preferably less than 80 mass %, more preferably less than 70 mass %, and then preferably less than 60 mass %. By making the containing ratio of specific liquid crystal be within the range, the haze value when no voltage is applied to liquid crystal element 10 can be made lower and the haze value when voltage is applied can be made higher, contrast characteristics can be made good, preferably with respect to the aspect.

[0067] Furthermore, based on the specific liquid crystal, it is believed that due to the main skeleton (1,2-diphenylethynyl skeleton, dicyclohexylcyanide skeleton) possessed by the specific liquid crystal, the refractive index anisotropy of the liquid crystal molecules in the liquid crystal layer becomes larger, thereby making the haze value when no voltage is applied lower and the haze value when voltage is applied higher, thereby obtaining a liquid crystal element exhibiting good optical properties.

[0068] (Polymerizable compound)

[0069] A polymerizable compound is a low molecular compound that can form a polymer by at least one of light and heat. The polymerizable compound is not particularly limited as long as it can be dissolved in liquid crystals, but is preferably a compound that exhibits free radical polymerizability. In terms of high light-induced free radical polymerizability, the free radical polymerizable group is preferably at least one selected from the group consisting of (meth)acryloyl, vinyl, vinyloxy, vinylphenyl (-C6H5-CH=CH2), allyl, maleimide and itaconic anhydride groups, and is particularly preferably (meth)acryloyl. Furthermore, in this specification, "(meth)acrylate" refers to a compound comprising acrylate and methacrylate. A "low molecular compound" is a compound that does not have a molecular weight distribution, and its molecular weight is preferably 1000 or less, more preferably 800 or less.

[0070] Examples of polymerizable compounds include monofunctional (meth)acrylate compounds, multifunctional (meth)acrylate compounds, and styrene-based compounds. As polymerizable compounds, liquid crystal compounds having one or more free radical polymerizable groups (hereinafter also referred to as "polymerizable liquid crystal compounds") can be preferably used. The use of polymerizable liquid crystal compounds can further improve the liquid crystal orientation of the liquid crystal element 10, which is preferred in this regard.

[0071] The polymerizable liquid crystal compound is preferably a compound having at least one of a substituted or unsubstituted aromatic ring and an aliphatic ring having a total of two or more. Furthermore, the aromatic ring includes an aromatic hydrocarbon ring and an aromatic heterocycle. The aromatic ring possessed by the polymerizable liquid crystal compound is preferably an aromatic hydrocarbon ring, and examples thereof include a benzene ring, a naphthalene ring, an anthracene ring, etc. Among these, a benzene ring is particularly preferred. As the aliphatic ring possessed by the polymerizable liquid crystal compound, examples thereof include a cyclohexane ring, a dodecylcyclohexane ring, etc., and a cyclohexane ring is preferred. The substituent that the aromatic ring or the aliphatic ring may have is preferably a fluorine atom, a cyano group, a hydroxyl group, or an alkyl group having 1 to 4 carbon atoms, an alkoxy group, a fluoroalkyl group, or an alkyl group containing a cyano group.

[0072] As polymerizable liquid crystal compounds, from the perspective of high reactivity to light, (meth)acrylic group-containing compounds having one or more (meth)acryloyl groups and a molecular weight of 1000 or less (hereinafter also referred to as "compound (RM)") are particularly preferred. From the perspective of further improving the liquid crystal orientation in a liquid crystal element without a liquid crystal alignment film, the number of (meth)acryloyl groups possessed by the compound (RM) is preferably 2 to 6, more preferably 2 to 4.

[0073] The compound (RM) preferably has a divalent aromatic ring group. The aromatic ring group possessed by the compound (RM) is a group formed by removing two hydrogen atoms from the ring portion of a substituted or unsubstituted aromatic ring, preferably a substituted or unsubstituted 1,4-phenylene group. From the viewpoint of imparting good liquid crystal orientation, the number of aromatic rings possessed by the compound (RM) is preferably 2 to 6, more preferably 2 to 4, and particularly preferably 2 or 3. The plurality of aromatic rings are preferably bonded via a single bond or a divalent linking group. From the viewpoint of improving the liquid crystal orientation using a rigid structure, the divalent linking group is preferably -COO-.

[0074] Specific examples of compound (RM) include compounds represented by the following formulas (r-1) to (r-6). Commercially available products of compound (RM) include polymerizable liquid crystals such as LC242 (manufactured by BASF) and RM257 (manufactured by Merck). However, compound (RM) is not limited to these compounds.

[0075] [Chemistry 4]

[0076]

[0077] (In formula (r-1) to formula (r-6), R A is a hydrogen atom or a methyl group; multiple R A Same or Different)

[0078] In the liquid crystal composition, the allocation ratio of the polymerizable compound can be suitably selected according to the type of liquid crystal cell used. In the case of being applied to a polymer dispersed liquid crystal cell, relative to the total amount of all the constituents of the liquid crystal composition, the allocation ratio of the polymerizable compound is preferably set to 0.05 mass % or more, more preferably set to 0.1 mass % or more, and then preferably set to 0.5 mass % or more. In addition, relative to the total amount of all the constituents of the liquid crystal composition, the allocation ratio of the polymerizable compound is preferably set to 30 mass % or less, more preferably set to 20 mass % or less, and then preferably set to 15 mass % or less. As a polymerizable compound, one can be used alone, or two or more can be used in combination.

[0079] Relative to the total amount of polymerizable compound, the allocation ratio of polymerizable liquid crystal compound is preferably 20 mass % or more, more preferably 30 mass % or more, and then preferably 50 mass % or more. Furthermore, polymerizable liquid crystal compound has liquid crystal properties, but is classified as polymerizable compound in this specification. When preparing liquid crystal composition, with regard to the viewpoint of obtaining the liquid crystal cell 10 with high transparency and the viewpoint of obtaining the liquid crystal cell with good optical properties after repeated drive tolerance and bending, it is especially preferred that polymerizable liquid crystal compound is used in combination with specific liquid crystal.

[0080] (Silicon-containing compounds)

[0081] The silicon-containing compound is preferably a silicon-containing polymer, more preferably a polyorganosiloxane. The polyorganosiloxane contained in the liquid crystal composition is preferably a polyorganosiloxane (hereinafter also referred to as "functional polyorganosiloxane") containing a functional group such as a group having a function of vertically aligning liquid crystal molecules (hereinafter also referred to as "liquid crystal orientation group") and a polymerizable group in the side chain. Furthermore, the functional group possessed by the functional polyorganosiloxane may be only one or more than two. The functional polyorganosiloxane preferably has at least a liquid crystal orientation group. By using a liquid crystal composition containing a polyorganosiloxane having a liquid crystal orientation group to form the liquid crystal layer 13, the heat resistance is high, and even if a liquid crystal orientation film is not provided, a liquid crystal element with high transparency, repeated drive resistance, bending resistance and optical properties after bending can be obtained, which is preferred in terms of the above aspects.

[0082] (Liquid Crystal Orientation Group)

[0083] Examples of the liquid crystal alignment group include an alkyl group having 4 to 20 carbon atoms, an alkoxy group having 4 to 20 carbon atoms, a fluoroalkyl group having 4 to 20 carbon atoms, a fluoroalkoxy group having 4 to 20 carbon atoms, a group having a structure in which one ring is bonded to a chain structure having 1 to 20 carbon atoms, a group having a structure in which two or more rings are bonded directly or via a divalent linking group, a group having a steroid skeleton, etc. Among these, the liquid crystal alignment group is preferably a group represented by the following formula (3).

[0084] *-L 1 -R 11 -R 12 -R 13 -R 14 ...(3)

[0085] (In formula (3), L 1 Single bond, -O-, -CO-, -COO-* 1 、-OCO-* 1 、-NR 15 -、-NR 15 -CO-* 1 、-CO-NR 15 -* 1 , an alkanediyl group having 1 to 6 carbon atoms, a divalent group in which a hydrogen atom of an alkanediyl group having 2 to 6 carbon atoms is substituted with a hydroxyl group, -OR 16 -* 1 or -R 16 -O-* 1 (Among them, R 15 is a hydrogen atom or a monovalent hydrocarbon group having 1 to 10 carbon atoms, R 16 is an alkanediyl group having 1 to 3 carbon atoms; 1 " indicates that the 11 bonding bond); R 11 and R 13 are each independently a single bond, a substituted or unsubstituted phenylene group, or a substituted or unsubstituted cycloalkylene group, R 12 is a single bond, a substituted or unsubstituted phenylene group, a substituted or unsubstituted cycloalkylene group, or -R 17 -B 1 -R 18 -(where R 17 and R 18 are independently substituted or unsubstituted phenylene or cycloalkylene, B 1 Single bond, -O-, -COO-* 2 、-OCO-* 2 、-OCH2-* 2 、-CH2O-* 2 or an alkanediyl group having 1 to 3 carbon atoms; "* 2 " indicates that the 18 bonding bond); R 14 A hydrogen atom, a fluorine atom, a cyano group, CH3COO-* 3 (“* 3 " indicates that the 13a bond), an alkyl group having 1 to 18 carbon atoms, a fluoroalkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, a fluoroalkoxy group having 1 to 18 carbon atoms, a hydrocarbon group having 17 to 51 carbon atoms with a steroid skeleton, or a monovalent group in which a hydrogen atom possessed by an alkyl group or a fluoroalkyl group having 1 to 18 carbon atoms is replaced by a cyano group; wherein, in R 11 、R 12 and R 13 All single bonds, or R 11 、R 12 and R 13 When the total number of substituted or unsubstituted phenylene groups and cycloalkylene groups is one, R 14 (alkyl group having 4 to 18 carbon atoms, fluoroalkyl group having 4 to 18 carbon atoms, alkoxy group having 4 to 18 carbon atoms, fluoroalkoxy group having 4 to 18 carbon atoms, or hydrocarbon group having 17 to 51 carbon atoms and a steroid skeleton; "*" indicates a bonding bond)

[0086] In the formula (3), L 1 The alkanediyl group is preferably straight-chain. 15 Examples of the monovalent hydrocarbon group having 1 to 10 carbon atoms include chain hydrocarbon groups, alicyclic hydrocarbon groups, and aromatic hydrocarbon groups, and an alkyl group having 1 to 3 carbon atoms is preferred.

[0087] About R 14 , an alkyl group having 1 to 18 carbon atoms, a fluoroalkyl group having 1 to 18 carbon atoms, an alkoxy group having 1 to 18 carbon atoms, a fluoroalkoxy group having 1 to 18 carbon atoms, or a monovalent group formed by replacing a hydrogen atom possessed by an alkyl group or a fluoroalkyl group having 1 to 18 carbon atoms with a cyano group is preferably a linear group. When the liquid crystal element is set to a vertical alignment system, these groups preferably have 2 to 18 carbon atoms, more preferably 3 to 18 carbon atoms, and even more preferably 4 to 18 carbon atoms. As R 14 Examples of the hydrocarbon group having 17 to 51 carbon atoms and a steroid skeleton include cholesteryl, cholesteryl, and lanostanyl.

[0088] From the viewpoint of obtaining a liquid crystal element that exhibits favorable liquid crystal orientation even without a liquid crystal alignment film, the liquid crystal alignment group is preferably R 11 、R 12 and R 13 The polyorganosiloxane may have a total of two or more, and more preferably two to four, of at least one selected from the group consisting of substituted or unsubstituted phenylene groups and substituted or unsubstituted cycloalkylene groups. Furthermore, the polyorganosiloxane having a liquid crystal alignment group may have a polymerizable group on its side chain along with the liquid crystal alignment group. Furthermore, the polyorganosiloxane having a polymerizable group is a component different from the polymerizable compound.

[0089] When the polyorganosiloxane contained in the liquid crystal composition has a liquid crystal orientation group, the content ratio of the liquid crystal orientation group relative to the total monomer units contained in the polyorganosiloxane is preferably 1 mol% or more, more preferably 2 mol% or more, and further preferably 5 mol% or more. In addition, the content ratio of the liquid crystal orientation group relative to the total monomer units contained in the polyorganosiloxane is preferably 70 mol% or less, more preferably 50 mol% or less, and further preferably 40 mol% or less. Furthermore, the polyorganosiloxane may have only one liquid crystal orientation group, or may have two or more.

[0090] (Synthesis of Polyorganosiloxane)

[0091] The polyorganosiloxane formulated in the liquid crystal composition can be prepared by, for example, the following methods: (I) a method of hydrolyzing and condensing a hydrolyzable silane compound having a functional group (polymerizable group or liquid crystal alignment group, etc.); (II) a method of using a hydrolyzable silane compound having an epoxy group (hereinafter also referred to as an "epoxy-containing silane compound") as a monomer and performing a hydrolysis and condensation reaction to obtain a polyorganosiloxane having an epoxy group, and then reacting the obtained epoxy-containing polyorganosiloxane with a carboxylic acid having a functional group to introduce a functional group into the side chain of the polyorganosiloxane; (III) a method of combining the method (I) with the method (II) to obtain a target polymer.

[0092] Examples of the silane compound used in the synthesis of the polyorganosiloxane include alkoxysilane compounds such as tetramethoxysilane, tetraethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, dimethyldimethoxysilane, and dimethyldiethoxysilane; and nitrogen- and sulfur-containing alkoxysilane compounds such as 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, mercaptomethyltrimethoxysilane, mercaptomethyltriethoxysilane, 3-ureidopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, and N-(3-cyclohexylamino)propyltrimethoxysilane.

[0093] Silane compounds containing epoxy groups, such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 2-(3,4-epoxycyclohexyl)ethyltriethoxysilane;

[0094] Alkoxysilane compounds containing unsaturated bonds, such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, 8-(meth)acryloxyoctyltrimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, and p-phenylenyltrimethoxysilane; and trimethoxysilylpropylsuccinic anhydride. Hydrolyzable silane compounds may be used alone or in combination of two or more. Furthermore, "(meth)acryloxy" encompasses both "acryloxy" and "methacryloxy."

[0095] The hydrolysis and condensation reactions can be carried out by reacting one or more of the aforementioned silane compounds with water, preferably in the presence of a suitable catalyst and an organic solvent. During the hydrolysis and condensation reactions, the proportion of water used is preferably 0.5 to 100 mol, more preferably 1 to 30 mol, per 1 mol of the silane compounds (total amount).

[0096] Examples of the catalyst used in the hydrolysis and condensation reactions include acids, alkali metal compounds, organic bases, titanium compounds, and zirconium compounds. The amount of the catalyst used varies depending on the type of catalyst, reaction conditions such as temperature, and should be appropriately set. For example, it is preferably 0.01 to 3 times the total amount of the silane compound, and more preferably 0.05 to 1 times the total amount.

[0097] Examples of the organic solvent used in the hydrolysis and condensation reactions include hydrocarbons, ketones, esters, ethers, and alcohols. Among these, water-insoluble or poorly water-soluble organic solvents are preferred. The proportion of the organic solvent used is preferably 10 to 10,000 parts by mass, more preferably 50 to 1,000 parts by mass, relative to 100 parts by mass of the total silane compound used in the reaction.

[0098] The hydrolysis and condensation reactions are preferably carried out by heating using an oil bath or the like. During the hydrolysis and condensation reactions, the heating temperature is preferably set to 130°C or less, more preferably to 40°C to 100°C. The heating time is preferably set to 0.5 hours to 12 hours, more preferably to 1 hour to 8 hours. During the heating process, the mixed solution may be stirred or placed under reflux. In addition, after the reaction is completed, it is preferred to use water to wash the organic solvent layer separated from the reaction solution. During the washing, water containing a small amount of salt (for example, an aqueous solution of ammonium nitrate of about 0.2% by mass) is used for washing, whereby the washing operation becomes easy, which is preferred in terms of the above aspect. The washing is carried out until the washed water layer becomes neutral, and then, after the organic solvent layer is dried using a desiccant such as anhydrous calcium sulfate or a molecular sieve as needed, the solvent is removed, thereby obtaining the target polyorganosiloxane. The synthesis method of polyorganosiloxane is not limited to the above-mentioned hydrolysis and condensation reactions, and may be performed, for example, by a method such as reacting a hydrolyzable silane compound in the presence of oxalic acid and an alcohol.

[0099] In the condensation reaction, by using an epoxy-containing silane compound as at least a portion of the raw materials, a polyorganosiloxane having epoxy groups in its side chains can be obtained. Alternatively, by reacting the obtained epoxy-containing polyorganosiloxane with a carboxylic acid having a functional group, a polyorganosiloxane having a functional group in its side chains can be obtained.

[0100] The reaction of the epoxy-containing polyorganosiloxane with the carboxylic acid is preferably carried out in an organic solvent in the presence of a catalyst as needed. Examples of the organic solvent used include alcohols, ethers, ketones, amides, esters, hydrocarbon compounds, and the like. As catalysts, organic bases such as tertiary organic amines or quaternary organic amines, quaternary ammonium salts, and the like can be used. The reaction temperature of the reaction is preferably set to 30°C to 120°C, and the reaction time is preferably set to 1 hour to 24 hours. Regarding the reaction solution in which the target polymer is dissolved, the polymer contained in the reaction solution can be separated using an existing separation method and then used for the preparation of a liquid crystal alignment agent.

[0101] The polyorganosiloxane has a polystyrene-equivalent weight average molecular weight (Mw) measured by gel permeation chromatography (GPC) preferably in the range of 100 to 50,000, more preferably in the range of 500 to 20,000, further preferably in the range of 1000 to 10,000, and even more preferably in the range of 1200 to 10,000.

[0102] In the liquid crystal composition, the proportion of the silicon-containing compound is suitably set according to the type of the silicon-containing compound. When the silicon-containing compound is polyorganosiloxane, the content of the polyorganosiloxane is preferably 0.0001% by mass or more relative to the total amount of the liquid crystal composition. If the content of the polyorganosiloxane is 0.0001% by mass or more, the silicon content of the boundary portion between the liquid crystal layer 13 and the substrate can be fully increased, and the adhesion between the liquid crystal layer 13 and the substrate, as well as the heat resistance, repeated drive resistance, bending resistance and optical properties after bending of the liquid crystal element 10 can be fully obtained, which is preferred in terms of the above aspects. From this viewpoint, the content of the polyorganosiloxane is more preferably 0.0005% by mass or more, and further preferably 0.001% by mass or more, relative to the total amount of the liquid crystal composition. In addition, from the viewpoint of maintaining the quality of the liquid crystal element 10 well, the content of the polyorganosiloxane is preferably 20% by mass or less, more preferably 15% by mass or less, relative to the total amount of the liquid crystal composition.

[0103] The liquid crystal composition of this embodiment may further contain other components in addition to the above-mentioned components as needed.

[0104] <Polymerization Initiator>

[0105] The liquid crystal composition may further contain a polymerization initiator. As the polymerization initiator, a photoradical polymerization initiator that generates free radicals by light can be preferably used. Examples of photoradical polymerization initiators include O-acyl oxime compounds, acetophenone compounds, and biimidazole compounds.

[0106] Specific examples of these O-acyl oxime compounds include 1,2-octanedione 1-[4-(phenylthio)-2-(O-benzoyl oxime)], ethyl ketone-1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-1-(O-acetyl oxime), ethyl ketone-1-[9-ethyl-6-(2-methyl-4-tetrahydrofurylmethoxybenzoyl)-9H-carbazol-3-yl]-1-(O-acetyl oxime), and ethyl ketone-1-[9-ethyl-6-{2-methyl-4-(2,2-dimethyl-1,3-dioxolanyl)methoxybenzoyl}-9H-carbazol-3-yl]-1-(O-acetyl oxime);

[0107] The acetophenone compound is preferably an α-aminoketone compound, and particularly includes 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butan-1-one, 2-dimethylamino-2-(4-methylbenzyl)-1-(4-morpholin-4-yl-phenyl)-butan-1-one, and 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropane-1-one.

[0108] Examples of the biimidazole compound include 2,2'-bis(2,4-dichlorophenyl)-4,4',5,5'-tetraphenyl-1,2'-biimidazole.

[0109] The polymerization initiator contained in the liquid crystal composition of the present disclosure can be appropriately selected from existing compounds. From the perspective of achieving improved durability by allowing curing to proceed to the interior of the liquid crystal layer 13, and achieving good adhesion between the substrate and the liquid crystal layer after the liquid crystal element is bent, it is preferred to use at least one polymerization initiator selected from the group consisting of acylphosphine oxide-based polymerization initiators, α-aminoalkylphenone-based polymerization initiators, α-hydroxyacetophenone-based polymerization initiators, and oxime ester-based polymerization initiators (hereinafter also referred to as "specific initiator"). Furthermore, the specific initiator used may be a single type or a mixture of two or more. Furthermore, a specific initiator and a photopolymerization initiator different from the specific initiator may be mixed and used.

[0110] Examples of the acylphosphine oxide-based polymerization initiator include bis(2,4,6-trimethylbenzoyl)-phenyl-phosphine oxide (for example, trade name: Irgacure 819, manufactured by BASF), bis(2,6-dimethoxybenzoyl)-2,4,4-trimethyl-pentylphenylphosphine oxide, and 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide (trade name: Lucirin TPO: manufactured by BASF).

[0111] Examples of the α-aminoalkylphenone-based polymerization initiator include 2-methyl-2-morpholino-1-(4-methylthiophenyl)propan-1-one and 2-dimethylamino-2-benzyl-1-(4-morpholinophenyl)butan-1-one.

[0112] Examples of the α-hydroxyacetophenone-based polymerization initiator include 1-hydroxycyclohexyl phenyl ketone and 2-hydroxy-2-methyl-1-phenylpropane-1-one.

[0113] Examples of the oxime ester polymerization initiator include 1,2-octanedione, 1-[4-(phenylthio)phenyl]-, 2-(O-benzoyloxime), ethyl ketone, and 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl]-, 1-(O-acetyloxime).

[0114] Relative to the total amount of the liquid crystal composition, the ratio of the polymerization initiator in the liquid crystal composition is preferably 0.001% by mass or more, more preferably 0.005% by mass or more. In addition, relative to the total amount of the liquid crystal composition, the ratio of the polymerization initiator is preferably 7.0% by mass or less, more preferably 5.0% by mass or less. By setting the ratio of the polymerization initiator to within the range, when the liquid crystal cell is irradiated with light, even if the exposure amount is reduced, the polymerization of the polymerizable compound can be promoted, and the alignment controllability of the liquid crystal molecules can be further improved, which is preferred in terms of the above aspect. Furthermore, as the polymerization initiator, one can be used alone, or two or more can be used in combination.

[0115] <Polymerization Inhibitor>

[0116] The liquid crystal composition may further contain a polymerization inhibitor. The polymerization inhibitor can be used, for example, to adjust the sensitivity of the liquid crystal composition to light. Examples of the polymerization inhibitor include phenol, hydroquinone, p-methoxyphenol, benzoquinone, methoxybenzoquinone, 1,2-naphthoquinone, cresol, catechols such as p-tert-butylcatechol, alkylphenols, alkylbisphenols, phenothiazine, 2,5-di-tert-butylhydroquinone, 2,6-di-tert-butylphenol, octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate, N,N′-hexamethylenebis(3,5-di-tert-butyl) -4-hydroxy-hydrocinnamic acid), 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 4,4'-methylenebis(2,6-di-tert-butylphenol), 4,4'-butylenebis(3-methyl-6-tert-butylphenol), 2,6-bis(2'-hydroxy-3'-tert-butyl-5'-methylbenzyl)4-methylphenol, 1,1,3-tris(2'-methyl-5'-tert-butyl-4'-hydroxyphenyl)butane, 1,3,5- Trimethyl-2,4,6-tris(3′-5′-di-tert-butyl-4′-hydroxybenzyl)benzene, triethylene glycol bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate, 2,4-dimethyl-6-tert-butylphenol, and 2-tert-butyl At least one of phenols such as 4-methoxyphenol, 6-tert-butyl-m-cresol, 2,6-di-tert-butyl-p-cresol, 2-tert-butylhydroquinone, methylene blue, copper dimethyldithiocarbamate, copper diethyldithiocarbamate, copper dipropyldithiocarbamate, copper dibutyldithiocarbamate, copper dibutyldithiocarbamate, copper salicylate, thiodipropionic acid esters, mercaptobenzimidazole, and phosphites. An oxygen-containing gas (such as air) may also be used in combination.

[0117] The proportion of the polymerization inhibitor used is not particularly limited, but is preferably 0.001% by mass or greater, more preferably 0.005% by mass or greater, relative to the total amount of the liquid crystal composition. Furthermore, the proportion of the polymerization inhibitor used is preferably 7.0% by mass or less, more preferably 5.0% by mass or less. The polymerization inhibitors may be used alone or in combination of two or more.

[0118] Other components contained in the liquid crystal composition, in addition to the above-mentioned components, include chiral agents (e.g., trade names "C-15" and "CB-15" (Merck)), antioxidants, ultraviolet absorbers, pigments, defoaming agents, photosensitizers, and compatibilizers. The proportions of the other components can be appropriately selected based on the individual components within a range that does not impair the effects of the present disclosure.

[0119] The liquid crystal composition is prepared by mixing a liquid crystal and a polymerizable compound, and optionally other ingredients. The mixing of these ingredients can be performed at room temperature or while heating. Alternatively, each ingredient can be dissolved in an organic solvent (e.g., acetone, chloroform, methanol, etc.), and then the solvent can be removed by, for example, distillation.

[0120] Method for manufacturing liquid crystal element

[0121] Next, a method for manufacturing the liquid crystal element 10 will be described. The liquid crystal element 10 can be manufactured using a method comprising the following steps: Step A, arranging a pair of substrates comprising a first substrate 11 and a second substrate 12 facing each other with a layer comprising a liquid crystal composition interposed therebetween to construct a liquid crystal cell; and Step B, curing the liquid crystal composition by irradiating the liquid crystal cell with light after construction. This manufacturing method does not include the step of forming a liquid crystal alignment film.

[0122] (Step A: Unit Construction Step)

[0123] In step A, two substrates with electrodes are prepared, and a layer of liquid crystal composition is arranged between the two substrates arranged in a manner that the electrode forming surfaces are opposite to each other to manufacture a liquid crystal cell. Specifically, the following methods can be cited: a method in which the peripheral portions of the first substrate 11 and the second substrate 12 are bonded together by a sealant and the liquid crystal composition is injected into the cell gap divided by the substrate surface and the sealant, and then the injection hole is sealed; a sealant is applied to the peripheral portion of the liquid crystal alignment film side of one of the substrates, and then the liquid crystal composition is dripped at several predetermined locations on the liquid crystal alignment film surface, and then the other substrate is bonded in a manner in which the liquid crystal alignment film 14 and the liquid crystal alignment film 15 face each other and the liquid crystal composition is spread over the entire surface of the substrate 11 and the substrate 12, and then the sealant is cured (one drop filling (ODF) method). As a sealant, for example, an epoxy resin containing a curing agent and alumina balls as a spacer can be used.

[0124] The obtained liquid crystal cell is preferably heated to a temperature at which the liquid crystal to be used acquires an isotropic phase and then slowly cooled to room temperature for annealing to remove the flow orientation during liquid crystal filling (annealing step). The heating temperature for the annealing treatment is appropriately set according to the liquid crystal to be used.

[0125] (Step B: Exposure Step)

[0126] In step B, the liquid crystal composition is cured by performing one or more treatments selected from heating and light irradiation. This curing reaction yields a liquid crystal layer 13 having a polymer network formed therein. When thermal curing is performed, the heating temperature is, for example, within the range of 40°C to 80°C. The heating time is preferably 0.5 to 5 minutes.

[0127] In the case of curing by light irradiation, unpolarized ultraviolet light with a wavelength in the range of 200 nm to 500 nm can be preferably used as the irradiation light. The irradiation dose of the light is preferably set to 50 mJ / cm 2 More preferably, it is 100 mJ / cm 2 In addition, the irradiation dose of light is preferably set to 10,000 mJ / cm 2 Below, more preferably 5,000 mJ / cm 2 The following is a description of the process. Irradiating the liquid crystal composition with light causes a polymerization reaction of the polymerizable compound contained in the liquid crystal composition to proceed. When a liquid crystal composition containing polyorganosiloxane is used, the polyorganosiloxane is present in the liquid crystal layer 13 in the liquid crystal element 10 at least near the interface with the substrates 11 and 12.

[0128] More specifically, it is preferable to irradiate the liquid crystal composition with light at 50 mW / cm 2 Exposure to light with a wavelength of 313 nm for less than 150 seconds or at a rate of 150 mW / cm 2 The above irradiation amount is performed by irradiating light with a wavelength of 365 nm for 150 seconds or less. From the perspective of obtaining a liquid crystal element 10 with higher transparency and light scattering and better heat resistance, repeated driving characteristics and optical characteristics after bending, the irradiation amount when irradiating light with a wavelength of 313 nm is more preferably set to 55 mW / cm 2 In addition, the irradiation dose when irradiating light with a wavelength of 313 nm is preferably set to 300 mW / cm 2 Below, more preferably set to 200mW / cm 2 Below, more preferably 100 mW / cm 2 the following.

[0129] The irradiation dose when irradiating light with a wavelength of 365 nm is more preferably 155 mW / cm 2 In addition, from the viewpoint of improving the yield when irradiating light with a wavelength of 365 nm, the irradiation amount is preferably set to 1000 mW / cm 2 Below, more preferably set to 500mW / cm 2 Below, more preferably set to 300mW / cm 2 the following.

[0130] The irradiation time when irradiating light having a wavelength of 313 nm or 365 nm is more preferably set to 1 second or longer, further preferably to 2 seconds or longer, and particularly preferably to 10 seconds or longer. Furthermore, the irradiation time is more preferably set to 120 seconds or shorter, further preferably to 100 seconds or shorter, and particularly preferably to 60 seconds or shorter. During the irradiation with light, at least one of heating the liquid crystal cell and applying a voltage between the electrodes of the liquid crystal cell may be performed.

[0131] The series of treatments of step A and step B can also be performed continuously. Therefore, for example, when a resin film substrate such as a TAC film, a (meth) acrylic film, or a polyethylene terephthalate (PET) film is used as the substrate 11 and the substrate 12 of the liquid crystal element 10, the liquid crystal element 10 can be manufactured by a roll-to-roll production method, which is preferred in terms of the above aspect. As an example, in the process of rewinding the film substrate wound into a roll, the liquid crystal cell is first produced by the ODF method through step A, and then the liquid crystal composition disposed between the pair of substrates is cured through step B to prepare the wound body. According to this production method, productivity on an industrial scale is high, low cost can be achieved, and the process advantages are great.

[0132] The liquid crystal element 10 can be used in various applications, such as windows of buildings, indoor and outdoor partitions (partitions), display windows, windows of vehicles (such as automobiles, airplanes, ships, and railways), various indoor and outdoor advertisements, guide signs, home appliances, mobile phones, smartphones, various monitors, clocks, portable game consoles, personal computers, glasses, sunglasses, medical equipment, furniture, and the like, and can be effectively used as a dimming element. Depending on the thickness, hardness, shape, and application of the element, the liquid crystal element 10 can be used directly or attached to glass or transparent resin.

[0133] (Second embodiment)

[0134] Next, the second embodiment will be described. In order to simplify the description, the description will be focused on the differences from the first embodiment.

[0135] The liquid crystal element of this embodiment is a polymer dispersed liquid crystal element, including: a pair of substrates including a first substrate 11 and a second substrate 12, and a liquid crystal layer 13 disposed between the first substrate 11 and the second substrate 12 (see Figure 1 ).

[0136] The liquid crystal composition for forming the liquid crystal layer 13 contains a liquid crystal and a polymerizable compound. As a liquid crystal, in addition to the liquid crystals exemplified in the first embodiment, for example, a liquid crystal composition with negative dielectric constant anisotropy commercially available as a liquid crystal composition for vertical alignment (VA) mode (for example, MLC-6608, MLC-6609, MLC-6610, MLC-6882, MLC-6686, MLC-7026-000, MLC-7026-100, MLC-7029, etc. manufactured by Merck) can be used as a raw material liquid crystal. The liquid crystal preferably has a negative dielectric constant anisotropy. Regarding the polymerizable compound, the description of the first embodiment can be applied. In addition, the liquid crystal composition preferably contains a silicon-containing compound, more preferably contains a polyorganosiloxane as the silicon-containing compound, and further preferably contains a functional polyorganosiloxane. The description of the first embodiment can be applied to the silicon-containing compound and the polyorganosiloxane.

[0137] In the second embodiment, when manufacturing a liquid crystal element, in step B, the liquid crystal element is heated at 50 mW / cm 2 Exposure to light with a wavelength of 313 nm for less than 150 seconds or at a rate of 150 mW / cm 2The liquid crystal composition is cured by irradiating with light at a wavelength of 365 nm for no more than 150 seconds at the above irradiation dose. By irradiating with light under these conditions, a liquid crystal element with high transparency and light scattering properties, as well as excellent heat resistance, repeated driving characteristics, and optical properties after bending, can be obtained. The description of the first embodiment applies to step B and other steps.

[0138] Example

[0139] Hereinafter, the present disclosure will be described in more detail with reference to Examples, but the present disclosure is not limited to these Examples.

[0140] In the following Examples and Comparative Examples, the weight average molecular weight and epoxy equivalent of the polymer were measured by the following methods.

[0141] [Weight average molecular weight of polymer]

[0142] The weight average molecular weight is a polystyrene-equivalent value measured by gel permeation chromatography under the following conditions.

[0143] Column: TSKgelGRCXLII manufactured by Tosoh Corporation

[0144] Solvent: tetrahydrofuran

[0145] Temperature: 40℃

[0146] Pressure: 68kgf / cm 2

[0147] [Epoxy equivalent]

[0148] The epoxy equivalent is measured by the hydrochloric acid-methyl ethyl ketone method described in Japanese Industrial Standards (JIS) C 2105.

[0149] The structural formulas of the compounds used in the present examples are shown below. hereinafter, for convenience, the "compound represented by formula (X)" may be simply referred to as "compound (X)".

[0150] [Chemistry 5]

[0151]

[0152] [Chemistry 6]

[0153]

[0154] [Chemistry 7]

[0155]

[0156] [Chemistry 8]

[0157]

[0158] <Synthesis of Polyorganosiloxane>

[0159] [Synthesis example 1]

[0160] Into a reaction vessel including a stirrer, a thermometer, a dropping funnel and a reflux cooling tube, 100 g of compound (a-1), 500 g of methyl isobutyl ketone and 10 g of triethylamine were added and mixed at room temperature. Subsequently, 100 g of deionized water was added dropwise from the dropping funnel over a period of 30 minutes, and the mixture was reacted at 80° C. for 6 hours while stirring under reflux. After the reaction was completed, the organic layer was taken out and washed with a 0.2% by mass aqueous solution of ammonium nitrate until the washed water became neutral. The solvent and water were then distilled off under reduced pressure to obtain a reactive polyorganosiloxane (ESSQ-1) in the form of a viscous transparent liquid. The reactive polyorganosiloxane (ESSQ-1) was subjected to 1 H-NMR analysis revealed a peak at a chemical shift (δ) of 3.2 ppm, indicating an epoxy group-derived peak. The resulting reactive polyorganosiloxane (ESSQ-1) had a weight-average molecular weight (Mw) of 3000 and an epoxy equivalent weight of 190 g / mol.

[0161] [Synthesis example 2]

[0162] Reactive polyorganosiloxane (ESSQ-2) was synthesized in the same manner as in Synthesis Example 1, except for the modifications described in Table 1 below, where the types and amounts of the monomers used were changed. In Table 1, the numerical values ​​in the monomer column represent the ratio (parts by mole) of each compound relative to 100 parts by mole of the total amount of the monomers used in the synthesis of the polyorganosiloxane. "-" in Table 1 indicates that the compound in the corresponding column was not used (the same applies to Tables 2, 3, and 5).

[0163] [Table 1]

[0164]

[0165] [Synthesis example 3]

[0166] In a 500 mL three-necked flask were placed 10.0 g of reactive polyorganosiloxane (ESSQ-1), 300 g of methyl isobutyl ketone as a solvent, 3.10 g of compound (b-1) as a modifying component (20 parts by mole relative to 100 parts by mole of monomer units in the reactive polyorganosiloxane), 3.24 g of compound (b-2) (10 parts by mole relative to 100 parts by mole of monomer units in the reactive polyorganosiloxane), and 0.10 g of UCAT 18X ​​(trade name, manufactured by San-Apro Co., Ltd.) as a catalyst, and the mixture was reacted at 100° C. with stirring for 48 hours. After the reaction, the solution obtained by adding ethyl acetate to the reaction mixture was washed with water three times, the organic layer was dried over magnesium sulfate, and the solvent was then distilled off to obtain 14.1 g of a polyorganosiloxane having polymerizable groups and aligning groups (referred to as polymer (PSQ-1)). The weight average molecular weight Mw of the obtained polymer was 8,200.

[0167] [Synthesis Example 4]

[0168] A polyorganosiloxane (PSQ-2) having an aligning group was synthesized in the same manner as in Synthesis Example 3, except that the types and amounts of the reactive polyorganosiloxane and the modifying component used were changed as described in Table 2 below. In Table 2, the numerical values ​​in the "modifying component" column represent the proportion (in parts by mole) of each modifying component compound used per 100 parts by mole of the number of monomer units in the reactive polyorganosiloxane used.

[0169] [Table 2]

[0170]

[0171] <Evaluation Method of Polymer Dispersed Liquid Crystal Cell>

[0172] The polymer-dispersed liquid crystal elements produced in the following Examples and Comparative Examples were evaluated by the following methods.

[0173] (1) Transparency evaluation

[0174] Regarding the polymer-dispersed liquid crystal elements manufactured in the examples and comparative examples, the transparency when no voltage was applied was evaluated by measuring the haze (HAZE) when no voltage was applied. The measurement was performed using a spectroscopic haze meter (manufactured by Tokyo Denshoku Co., Ltd.). Regarding the evaluation, a haze value of less than 3% was rated as "good (○)", a haze value of 3% or more and less than 10% was rated as "acceptable (Δ)", and a haze value of 10% or more was rated as "poor (×)".

[0175] (2) Evaluation of light scattering

[0176] The light scattering properties of the polymer dispersed liquid crystal elements manufactured in the examples and comparative examples were evaluated by measuring the haze value under the applied voltage. The measurement was performed by applying 40V to the polymer dispersed liquid crystal element by AC drive and using a spectrophotometer (manufactured by Tokyo Denshoku Co., Ltd.) in the same manner as described in (1). Regarding the evaluation, the case where the haze value was greater than 90% was designated as "good (○)", the case where it was less than 90% and greater than 85% was designated as "acceptable (Δ)", and the case where it was less than 85% was designated as "poor (×)".

[0177] (3) Evaluation of adhesion

[0178] The tensile strength of the polymer dispersed liquid crystal element was measured by applying tension to the polymer dispersed liquid crystal element manufactured in the examples and comparative examples until it broke, and the adhesion was evaluated based on the measured value. The measurement was performed by fixing one of the substrates of the polymer dispersed liquid crystal element and applying tension to the other substrate using a small desktop tester (manufactured by Shimadzu Corporation). Regarding the evaluation, the case where the maximum stress was greater than 40N was set as "good (○)", the case where it was less than 40N and greater than 20N was set as "acceptable (Δ)", and the case where it was less than 20N was set as "poor (×)".

[0179] (4) Evaluation of heat resistance

[0180] The polymer dispersed liquid crystal elements manufactured in the examples and comparative examples were stored in an oven at 100°C for 200 hours. After 200 hours, the polymer dispersed liquid crystal elements were taken out and the haze value HA1 in the state where no voltage was applied and the haze value HA2 in the state where voltage was applied were measured. Regarding the evaluation, the value of ΔHZ1 obtained by the following formula (1) was set to "excellent (◎)" when it was less than 5%, "good (○)" when it was more than 5% and less than 7.5%, "acceptable (Δ)" when it was more than 7.5% and less than 10%, and "poor (×)" when it was more than 10%.

[0181] ΔHZ1=(HB2-HB1)-(HA2-HA1)...(1)

[0182] (In formula (1), HB1 is the haze value measured before heat application with no voltage applied, HB2 is the haze value measured before heat application with voltage applied, HA1 is the haze value measured after heat application with no voltage applied, and HA2 is the haze value measured after heat application with voltage applied)

[0183] (5) Evaluation of repeated driving performance

[0184] After applying a voltage of 40V for 1 hour to the polymer dispersed liquid crystal elements manufactured in the examples and comparative examples by AC drive, the state of no voltage application is maintained for 1 hour. The voltage application-no application action is counted as 1 time, and repeated 100 times. Thereafter, the haze value HC1 in the state of no voltage application and the haze value HC2 in the state of voltage application are measured. Regarding the evaluation, the case where the ΔHZ2 obtained by the following formula (2) is less than 3% is set as "good (○)", the case where it is more than 3% and less than 10% is set as "acceptable (Δ)", and the case where it is more than 10% is set as "poor (×)".

[0185] AHZ2=(HB2-HB1)-(HC2-HCl)...(2)

[0186] (In formula (2), HB1 is the haze value measured before repeated driving with no voltage applied, HB2 is the haze value measured before repeated driving with voltage applied, HC1 is the haze value measured after repeated driving with no voltage applied, and HC2 is the haze value measured after repeated driving with voltage applied)

[0187] (6) Evaluation of bending resistance

[0188] The polymer dispersed liquid crystal elements manufactured in the examples and comparative examples were wound around a metal rod with a diameter of 2 cm. Thereafter, the adhesion was evaluated in the same manner as in (3). Regarding the evaluation, the case where the maximum stress was greater than 40 N was rated as "excellent (◎)", the case where the maximum stress was less than 40 N and greater than 30 N was rated as "good (○)", the case where the maximum stress was less than 30 N and greater than 20 N was rated as "acceptable (Δ)", and the case where the maximum stress was less than 20 N was rated as "poor (×)".

[0189] (7) Optical properties after bending resistance test

[0190] As in the evaluation of bending resistance (6), the polymer-dispersed liquid crystal element was wound around a metal rod with a diameter of 2 cm, and the transparency and light scattering properties were measured by the same procedures as (1) and (2). Regarding the evaluation, if the ΔHZ3 obtained by the following formula (3) was less than 5%, it was rated as "good (○)", if it was 5% or more and less than 10%, it was rated as "acceptable (Δ)", and if it was 10% or more, it was rated as "poor (×)".

[0191] ΔHZ3=(HB2-HB1)-(HD2-HD1)...(3)

[0192] (In formula (3), HB1 is the haze value measured before the bending resistance test in a state where no voltage is applied, HB2 is the haze value measured before the bending resistance test in a state where a voltage is applied, HD1 is the haze value measured after the bending resistance test in a state where no voltage is applied, and HD2 is the haze value measured after the bending resistance test in a state where a voltage is applied)

[0193] (8) Contrast evaluation

[0194] Contrast evaluation was performed on the polymer dispersed liquid crystal elements manufactured in the examples and comparative examples, in which a pigment was mixed in the liquid crystal layer, using a spectrophotometer (150-20 Double Beam manufactured by Hitachi, Ltd.). For the evaluation, the light transmittance (%) was first measured in a state where no voltage was applied, and the average value of the light transmittance at wavelengths of 450nm, 550nm, and 650nm was calculated. Secondly, the light transmittance (%) was measured in a state where a voltage of 40V was applied by AC drive, and the average value of the light transmittance at wavelengths of 450nm, 550nm, and 650nm was calculated. Then, the contrast (C value) was calculated according to the following formula (4).

[0195] C value = light transmittance in the state without voltage applied / light transmittance in the state with voltage applied...(4)

[0196] The evaluation was performed by rating a C value of 15% or greater as "good (○)" and a value of less than 15% as "poor (×)." The higher the light transmittance in the unapplied state, the higher the light transmittance, while the lower the light transmittance during voltage operation, the higher the light shielding properties and the better the contrast.

[0197] (9) Adhesion after bending resistance test

[0198] As in the evaluation of bending resistance (6), the polymer-dispersed liquid crystal element was wound around a metal rod with a diameter of 2 cm, and the tensile strength was measured by the same operation as in (3) to evaluate the adhesion. The evaluation was performed on the basis of "good (○)" when the maximum stress was greater than 30 N, "acceptable (Δ)" when the maximum stress was less than 30 N and greater than 20 N, and "poor (×)" when the maximum stress was less than 20 N.

[0199] [First embodiment]

[0200] <Manufacturing and Evaluation of Polymer-Dispersed Liquid Crystal Cells>

[0201] [Example 1A]

[0202] (1) Preparation of liquid crystal composition

[0203] A liquid crystal composition (PLC-X1) (see Table 3) was obtained by adding compound (d-1), compound (e-1), compound (f-1), compound (RM-2) and polymer (PSQ-1) in an amount such that the content ratio of each component relative to the total amount of all components of the liquid crystal composition was 0.01 mass%, 3 mass%, 15 mass%, 3 mass% and 1 mass%, respectively.

[0204] (2) Manufacturing of polymer dispersed liquid crystal elements

[0205] Prepare a pair of PET film substrates (PET-ITO substrates) 10 cm square with ITO electrodes on the surface. No liquid crystal alignment film is formed on the two substrates, and an 18 μm spacer is coated on the electrode configuration surface of one of the substrates. Thereafter, the prepared liquid crystal composition (PLC-X1) is dripped onto the surface coated with the spacer. Then, the two substrates are bonded together with a sealant in such a way that the electrode configuration surfaces of the two substrates face each other to obtain a liquid crystal unit. Then, the obtained liquid crystal unit is heated on a hot plate at 80°C (annealing step). The annealing step is a step of heating to a temperature above the liquid crystal phase transition temperature at which the liquid crystal becomes an isotropic phase. Next, after the liquid crystal unit is lowered to room temperature, an ultraviolet irradiation device with a high-pressure mercury lamp as a light source and equipped with a bandpass filter that transmits wavelengths near 313 nm is used to irradiate the liquid crystal unit at a wavelength of 313 nm and an ultraviolet intensity of 60 mW / cm 2 The liquid crystal cell was irradiated with unpolarized ultraviolet light for 30 seconds (exposure step) to cure the liquid crystal composition (PLC-X1), thereby obtaining a polymer-dispersed liquid crystal element. During the ultraviolet irradiation, the substrate surface temperature was not increased, and no voltage was applied to the liquid crystal cell.

[0206] (3) Determination of surface coverage

[0207] Then, about the obtained polymer dispersed liquid crystal element, by utilizing hand to peel off the liquid crystal layer from two PET-ITO substrates, the liquid crystal layer is peeled off from the substrate at the boundary portion of the liquid crystal layer and the substrate. On the entire surface of the ITO electrode surface of the substrate from which the liquid crystal layer has been peeled, the concave-convex caused by the residual of the liquid crystal layer was visually confirmed. Then, the substrate after peeling was immersed in hexane at 23 ° C for 30 seconds, immersed and cleaned, and air-dried. XPS (manufactured by Japan Vacuum (ULVAC-PHI) Company) was used to perform elemental analysis on the surface of the ITO electrode surface of the dried substrate, and the ratio of the total of the carbon atoms, oxygen atoms and silicon atoms on the ITO electrode (silicon surface coverage) of the silicon atoms was calculated. As a result, the silicon surface coverage in this embodiment is that in the two substrates of the polymer dispersed liquid crystal element, the value of the substrate (liquid crystal dripping substrate) side to which the liquid crystal composition (PLC-X1) was added was 1.02%, and the value of the other substrate (facing substrate) side was 0.96%.

[0208] (4) Evaluation of polymer dispersed liquid crystal elements

[0209] The polymer-dispersed liquid crystal element produced in (2) was used to perform the evaluations (1) to (7) and (9) in the <Evaluation Method of Polymer-dispersed Liquid Crystal Element>. The evaluation results are shown in Table 4 below.

[0210] [Example 2A to Example 10A and Comparative Examples 1A to Comparative Examples 3A]

[0211] The formulation of the liquid crystal composition is changed as shown in Table 3 below. Except for the above aspects, liquid crystal compositions (PLC-X2) to liquid crystal compositions (PLC-X13) are prepared in the same manner as in Example 1A. The numerical values ​​in brackets in Table 3 represent the formulation amounts. In addition, using the prepared liquid crystal compositions, a polymer-dispersed liquid crystal element is manufactured in the same manner as in Example 1A, and various evaluations are performed in the same manner as in Example 1A. The results of these evaluations are shown in Table 4 below. Furthermore, with respect to Example 3A, Example 4A, Example 6A and Example 8A, and Comparative Example 2A and Comparative Example 3A, an ultraviolet irradiation device using an ultraviolet irradiation diode as a light source is used. Except for the above aspects, non-polarized ultraviolet rays are irradiated under the same conditions as in Example 1A to harden the liquid crystal composition and obtain a polymer-dispersed liquid crystal element. With respect to Example 7A, an ultraviolet irradiation device using an ultraviolet irradiation diode as a light source is used, and the ultraviolet light intensity is 160mW / cm 2 The liquid crystal composition was cured by irradiating with non-polarized ultraviolet light for 60 seconds to obtain a polymer dispersed liquid crystal element. The evaluation of (9) was performed on Example 9A and Example 10A.

[0212]

[0213] The abbreviations in Table 3 are as follows.

[0214] ACR-1: Dipentaerythritol hexaacrylate

[0215] TEOS: Tetraethoxysilane

[0216] ODTES: n-octadecyltriethoxysilane

[0217] [Table 4]

[0218]

[0219] As shown in Table 4, even without a liquid crystal alignment film, Examples 1A to 10A showed various properties (transparency, light scattering, adhesion, heat resistance, repeated driving characteristics, bending resistance, and optical properties after the bending resistance test) rated "◎," "○," or "Δ." In contrast, Comparative Examples 1A to 3A were rated "×" in two or more evaluation items, indicating inferiority compared to Examples 1A to 10A.

[0220] That is, in the examples where the silicon surface coverage was less than 0.04% (Comparative Examples 1A to 3A), both the bending resistance and the optical characteristics after the bending resistance test were evaluated as "×". In contrast, in the examples where the silicon surface coverage was greater than 0.06% (Example 1A to Example 10A), the bending resistance and the optical characteristics after the bending resistance test were "◎", "○", or "Δ", which were excellent compared to the comparative examples. In addition, in the examples where the silicon surface coverage was greater than 0.06%, the transparency and light scattering properties were evaluated as "○" or "Δ", which are good basic characteristics of polymer liquid crystal elements. In addition, the adhesion, heat resistance, and repeated drive characteristics were also evaluated as "◎", "○", or "Δ". In particular, in the examples where the silicon surface coverage was within the range of greater than 0.10% and less than 5.0% (Example 1A, Example 3A, Example 5A to Example 10A), all the evaluation items were "◎" or "○", which were particularly excellent.

[0221] In the examples (Examples 1A to 10A) of using a liquid crystal composition containing a specific liquid crystal and a polymerizable liquid crystal compound to form a liquid crystal layer in a liquid crystal element without a liquid crystal alignment film, the bending resistance and the optical properties after the bending resistance test were "◎", "○" or "Δ". In these examples, the evaluations of transparency and light scattering were "○" or "Δ", which were also good as basic properties of polymer liquid crystal elements. In addition, in the examples, the evaluations of adhesion, heat resistance and repeated drive characteristics were also "◎", "○" or "Δ", which were excellent compared to Comparative Examples 1A to 3A.

[0222] In addition, according to the results of Example 9A and Example 10A, by using an α-hydroxyacetophenone-based polymerization initiator or an acylphosphine oxide-based polymerization initiator, the transparency, light scattering, adhesion, heat resistance, repeated driving characteristics, bending resistance and optical properties after the bending resistance test can be maintained, and the adhesion after the bending resistance test can be improved, thereby obtaining an excellent polymer-dispersed liquid crystal element.

[0223] [Second embodiment]

[0224] <Manufacturing and Evaluation of Polymer Liquid Crystal Cells>

[0225] In the second embodiment, the relationship between exposure conditions and device characteristics was studied.

[0226] [Example 1B]

[0227] (1) Preparation of liquid crystal composition

[0228] Compound (d-1), compound (e-1), compound (f-1), compound (RM-1) and polymer (PSQ-1) were added to 10 g of nematic liquid crystal (manufactured by Merck, MLC-6608) in a manner such that the content ratio of each component relative to the total amount of all components of the liquid crystal composition was 0.01 mass%, 3 mass%, 15 mass%, 5 mass% and 0.001 mass%, respectively, and mixed to obtain a liquid crystal composition (PLC-1) (see Table 5).

[0229] (2) Manufacturing of polymer dispersed liquid crystal elements

[0230] Prepare a pair of PET film substrates (PET-ITO substrates) 10 cm square with ITO electrodes on the surface. No liquid crystal orientation film is formed on the two substrates, and an 18 μm spacer is coated on the electrode configuration surface of one of the substrates. Thereafter, the prepared liquid crystal composition (PLC-1) is dripped onto the surface coated with the spacer. Then, the two substrates are bonded together with a sealant in such a way that the electrode configuration surfaces of the two substrates face each other to obtain a liquid crystal unit. Then, the obtained liquid crystal unit is heated on a hot plate at 80°C to a temperature above the liquid crystal phase transition temperature at which the liquid crystal becomes an isotropic phase (annealing step). Next, after the liquid crystal unit is lowered to room temperature, an ultraviolet irradiation device with an ultraviolet light emitting diode as a light source is used at a wavelength of 313 nm and an ultraviolet intensity of 60 mW / cm 2 The liquid crystal cell was irradiated with unpolarized ultraviolet light for 30 seconds (exposure step) to cure the liquid crystal composition (PLC-1), thereby obtaining a polymer-dispersed liquid crystal element. During the ultraviolet irradiation, the substrate surface temperature was not increased, and no voltage was applied to the liquid crystal cell during the irradiation.

[0231] (3) Evaluation of polymer dispersed liquid crystal elements

[0232] The polymer-dispersed liquid crystal element produced in (2) was used to perform the evaluations (1) to (7) and (9) described in the <Evaluation Method of Polymer-dispersed Liquid Crystal Element>. The evaluation results are shown in Table 6 below.

[0233] [Example 2B to Example 13B and Comparative Examples 1B to Comparative Examples 3B]

[0234] The formulation of the liquid crystal composition was changed as shown in Table 5 below. Except for the above aspects, liquid crystal compositions (PLC-2) to (PLC-6) were prepared in the same manner as in Example 1B. In addition, each of the prepared liquid crystal compositions was used to manufacture a polymer-dispersed liquid crystal element in the same manner as in Example 1B, and various evaluations were performed in the same manner as in Example 1B. The results of these evaluations are shown in Table 6 below. Furthermore, in Examples 8B to 10B, at least one of a treatment of heating to 60°C during ultraviolet irradiation and a treatment of applying a DC voltage of 10V was performed in the exposure step after the annealing step (see Table 6). Example 13B was evaluated in (9).

[0235] In addition, in Example 12B using the liquid crystal composition (PLC-5), "(3) Adhesion" and "(8) Contrast Evaluation" were performed in the evaluation items described in the <Evaluation Method of Polymer Dispersed Liquid Crystal Element>. As a result, in Example 12B, the light transmittance when no voltage was applied was 91%, the light transmittance when an AC drive of 40V was applied was 5%, the C value was 18%, and the contrast was evaluated as "good (○)". Similarly, the contrast was evaluated for Comparative Example 3B, but it was evaluated as "poor (×)".

[0236] [Table 5]

[0237]

[0238]

[0239] As shown in Table 6, in Examples 1B to 11B and 13B, even without a liquid crystal alignment film, various properties (transparency, light scattering, adhesion, heat resistance, repeated drive characteristics, and optical properties after the bending resistance test) were rated "◎," "○," or "Δ." In contrast, in Comparative Examples 1B and 2B, four or five evaluation items were rated "×," indicating inferiority compared to Examples 1B to 11B and 13B. Furthermore, in Example 12B, which incorporated a pigment, adhesion and contrast were rated "○," whereas in Comparative Example 3, all evaluations were rated "×."

[0240] In addition, according to the results of Example 13B, by using an acylphosphine oxide-based polymerization initiator, the transparency, light scattering, adhesion, heat resistance, repeated driving characteristics, bending resistance and optical properties after the bending resistance test can be maintained, while the adhesion after the bending resistance test is improved, thereby obtaining an excellent polymer-dispersed liquid crystal element.

Claims

1. A liquid crystal element comprising: A first substrate is provided with a first electrode; a second substrate provided with a second electrode and arranged facing the first substrate; as well as a liquid crystal layer disposed adjacent to the first substrate and the second substrate and formed by curing a liquid crystal composition containing a liquid crystal and a polymerizable compound; The liquid crystal element does not have a liquid crystal alignment film, The liquid crystal layer is peeled off from at least one of the first substrate and the second substrate, the substrate from which the liquid crystal layer is peeled off is immersed in hexane at 23°C for 30 seconds and dried, and when the surface of the substrate on the peeled side after drying is measured by X-ray photoelectron spectroscopy, the proportion of silicon atoms relative to the total amount of carbon atoms, oxygen atoms and silicon atoms is greater than 0.05% and less than 10%. 2 . The liquid crystal element according to claim 1 , wherein the liquid crystal comprises at least one selected from the group consisting of a liquid crystal containing a cyclohexyl cyanide group and a liquid crystal containing a tolan structure. 3 . The liquid crystal element according to claim 1 , wherein the liquid crystal composition contains polyorganosiloxane. The liquid crystal element according to claim 3 , wherein the polyorganosiloxane has a liquid crystal alignment group. The liquid crystal element according to claim 3 , wherein the polyorganosiloxane has a polymerizable group. 6 . The liquid crystal element according to claim 1 , wherein the polymerizable compound contains a (meth)acryloyl group-containing compound having a molecular weight of 1000 or less.

7. The liquid crystal element according to claim 1 or 2, wherein the liquid crystal composition contains at least one selected from the group consisting of an acylphosphine oxide-based polymerization initiator, an α-aminoalkylphenone-based polymerization initiator, an α-hydroxyacetophenone-based polymerization initiator, and an oxime ester-based polymerization initiator.

8. A method for manufacturing a liquid crystal element, comprising: A step of constructing a liquid crystal cell by arranging a first substrate provided with a first electrode and a second substrate provided with a second electrode to face each other via a layer containing a liquid crystal composition containing a liquid crystal and a polymerizable compound; as well as a step of curing the liquid crystal composition to form a liquid crystal layer by irradiating the liquid crystal cell with light; The liquid crystal element does not have a liquid crystal alignment film, the liquid crystal layer is peeled off from at least one of the first substrate and the second substrate, the substrate from which the liquid crystal layer is peeled off is immersed in hexane at 23°C for 30 seconds and dried, and when the surface of the substrate on the peeled side after drying is measured by X-ray photoelectron spectroscopy, the proportion of silicon atoms relative to the total amount of carbon atoms, oxygen atoms and silicon atoms is greater than or equal to 0.05% and less than or equal to 10%.

9. The method for manufacturing a liquid crystal element according to claim 8, wherein the liquid crystal element is 2 Exposure to light with a wavelength of 313 nm for less than 150 seconds or at a rate of 150 mW / cm 2 The liquid crystal composition is cured by irradiating light with a wavelength of 365 nm for 150 seconds or less at the above irradiation amount.

10. A method for manufacturing a liquid crystal element, comprising: A step of constructing a liquid crystal cell by arranging a first substrate provided with a first electrode and a second substrate provided with a second electrode to face each other via a layer containing a liquid crystal composition containing a liquid crystal and a polymerizable compound; as well as a step of curing the liquid crystal composition by irradiating the liquid crystal cell with light, The liquid crystal element does not have a liquid crystal alignment film, By 50mW / cm 2 Exposure to light with a wavelength of 313 nm for less than 150 seconds or at a rate of 150 mW / cm 2 The liquid crystal composition is cured by irradiating light with a wavelength of 365 nm for 150 seconds or less at the above irradiation amount.

11. The method for producing a liquid crystal element according to any one of claims 8 to 10, wherein the liquid crystal composition contains at least one selected from the group consisting of an acylphosphine oxide-based polymerization initiator, an α-aminoalkylphenone-based polymerization initiator, an α-hydroxyacetophenone-based polymerization initiator, and an oxime ester-based polymerization initiator.

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