CN118805104A - Liquid crystal composition, light reflecting layer, optical laminate and ophthalmic device - Google Patents

Abstract

The present invention relates to a liquid crystal composition comprising: a liquid crystal compound and at least one alkyl glycol di(meth)acrylate selected from the group consisting of an alkyl glycol diacrylate represented by the following formula (1) and an alkyl glycol dimethacrylate represented by the following formula (2), wherein the content of the alkyl glycol di(meth)acrylate is 5 parts by mass or more and 25 parts by mass or less based on 100 parts by mass of the liquid crystal compound. In formula (1), n represents an integer from 4 to 12, In formula (2), n represents an integer of 4 to 12.

Description

Liquid crystal composition, light reflecting layer, optical laminate and ophthalmic device

Technical Field

The present invention relates to a liquid crystal composition, and a light reflecting layer, an optical laminate and an ophthalmic device formed using the liquid crystal composition.

Background Art

Eyewear (sunglasses, goggles, goggles, etc.) is used to reduce the glare caused by reflected light from water, road, snow, etc. Generally speaking, since the reflected light from the water and snow has the property of being polarized, polarized sunglasses are particularly effective against these reflected lights. Since polarized sunglasses are designed to effectively absorb light in the polarization direction, they can reduce glare and improve viewing without significantly reducing the amount of incident light to the eyes.

The optical film used in polarized sunglasses usually has a structure in which a polarizing element is sandwiched by a supporting material such as polycarbonate. Such an optical film can be processed into a desired shape and embedded in a frame to make polarized sunglasses. The polarizing element is a film of so-called dichroic pigments such as dichroic dyes, polyiodine-polyvinyl alcohol (PVA: Polyvinyl Alcohol) complexes, and polymers such as PVA after uniaxial alignment, and polarizing elements of various colors are obtained by the color of the pigment used. In the case of ordinary sunglasses, in order to impart polarization to the entire visible light region, the polarizing element is mostly colored in gray.

In order to add design to polarized sunglasses or further improve visibility, a multilayer film is sometimes deposited on the surface. By applying a multilayer film, other people who do not wear polarized sunglasses can see the reflected light on the surface of the sunglasses in metallic tones such as blue, green, and red, and for the wearer, since specific light is reflected, the glare can be reduced and the visibility of the scenery through the lens can be further improved. Applying a multilayer film is beneficial to the wearer, but there is a problem in that sebum and the like are difficult to remove when attached to the multilayer film, and the multilayer film may peel off in places exposed to moisture and sea breeze such as the seaside.

For such a problem, a method of placing the multilayer film on the inner side of the support material, that is, between the polarizing element and the support material can be considered. However, the multilayer film shows the reflection performance through the refractive index difference between each layer, so it is difficult for the multilayer film to obtain the same reflection performance as that at the air interface. In addition, since the multilayer film is made of inorganic substances, there are also problems with the adhesion of the polarizing element which is an organic substance.

On the other hand, a method of using a cholesteric liquid crystal layer to impart a metallic hue to reflected light using an organic substance instead of a multilayer film is known (e.g., Patent Document 1). Cholesteric liquid crystal is a state in which liquid crystal molecules are in a spiral alignment, and has the function of selectively reflecting a circularly polarized light component in the same direction as the spiral direction of the liquid crystal molecules in a specific wavelength region by the length of the spiral pitch. An optical laminate using a cholesteric liquid crystal layer in which the spiral alignment is fixed so that light is reflected in a desired wavelength region exhibits reflected light of a vivid hue and can impart decorativeness to various components.

Prior art literature

Patent Literature

Patent document 1: International Publication No. 2016/002582.

Summary of the invention

[Problems to be Solved by the Invention]

In addition, since the reflection band of cholesteric liquid crystal is narrower than that of multilayer film, sunglasses using cholesteric liquid crystal layer have the advantage that the transmitted light is not easily dimmed when worn. In recent years, it is expected that optical laminates with narrower reflection bands can be developed using cholesteric liquid crystal layers.

Therefore, an object of the present invention is to provide a liquid crystal composition that can form an optical laminate having a light-reflecting layer in which a cholesterol liquid crystal phase is fixed and has a narrow reflection band. In addition, an object of the present invention is to provide a light-reflecting layer, an optical laminate and an ophthalmic device formed from the liquid crystal composition.

[Technical means to solve the problem]

The liquid crystal composition of the embodiment of the present invention contains: a liquid crystal compound and at least one alkyl glycol di(meth)acrylate selected from the group consisting of an alkyl glycol diacrylate represented by the following formula (1) and an alkyl glycol dimethacrylate represented by the following formula (2);

The content of the alkyl glycol di(meth)acrylate is 5 parts by mass or more and 25 parts by mass or less relative to 100 parts by mass of the liquid crystal compound.

In the formula, n represents an integer from 4 to 12,

In the formula, n represents an integer from 4 to 12.

The light reflecting layer according to the embodiment of the present invention includes a cholesteric liquid crystal layer in which the cholesteric liquid crystal phase of the liquid crystal composition is fixed.

The optical layered body according to the embodiment of the present invention includes the light reflecting layer and a substrate.

An ophthalmic instrument according to an embodiment of the present invention includes the light reflecting layer or the optical layered body.

[Effects of the invention]

The present invention can provide a liquid crystal composition capable of forming an optical laminate having a light reflecting layer in which a cholesterol liquid crystal phase is fixed and having a narrow reflection band. In addition, the present invention can provide a light reflecting layer, an optical laminate and an ophthalmic device formed from the liquid crystal composition.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing one embodiment of an optical layered body including a light reflecting layer according to the present invention.

FIG. 2 is a scatter diagram showing the maximum reflectance and the reflection band of the optical layered bodies prepared in Examples 1 to 10 and Comparative Examples 1 to 5. FIG.

FIG. 3 shows spectrum data of the optical layered body produced in Example 1. FIG.

FIG. 4 shows spectrum data of the optical layered body produced in Example 2. FIG.

FIG. 5 shows spectrum data of the optical layered body produced in Example 3. FIG.

FIG. 6 shows spectrum data of the optical layered body produced in Example 4. FIG.

FIG. 7 shows spectrum data of the optical layered body produced in Example 5. FIG.

FIG. 8 shows spectrum data of the optical layered body produced in Example 6. FIG.

FIG. 9 shows spectrum data of the optical layered body produced in Example 7. FIG.

FIG. 10 shows spectrum data of the optical layered body produced in Example 8. FIG.

FIG. 11 shows spectrum data of the optical layered body produced in Example 9. FIG.

FIG. 12 shows spectrum data of the optical layered body produced in Example 10. FIG.

FIG. 13 shows spectrum data of the optical layered body produced in Comparative Example 1. FIG.

FIG. 14 shows spectrum data of the optical layered body produced in Comparative Example 2. FIG.

FIG. 15 shows spectrum data of the optical layered body produced in Comparative Example 3. FIG.

FIG. 16 shows spectrum data of the optical layered body produced in Comparative Example 4. FIG.

FIG. 17 shows spectrum data of the optical layered body produced in Comparative Example 5. FIG.

FIG. 18 shows spectrum data of the optical layered body produced in Example 11. FIG.

FIG. 19 shows spectrum data of the optical layered body produced in Example 12. FIG.

FIG. 20 shows spectrum data of the optical layered body produced in Example 13. FIG.

FIG. 21 shows spectrum data of the optical layered body produced in Example 14. FIG.

FIG. 22 shows spectrum data of the optical layered body produced in Example 15. FIG.

DETAILED DESCRIPTION

The present invention will be described in detail below. The embodiments shown below are merely examples of typical embodiments used to specifically describe the present invention, and various embodiments can be adopted within the scope of the present invention.

In addition, the numerical range expressed using "to" means a range including the numerical values described before and after "to" as the lower limit and the upper limit.

<Liquid Crystal Composition>

The liquid crystal composition contains: a liquid crystal compound, and at least one alkyl glycol di(meth)acrylate selected from alkyl glycol diacrylate and alkyl glycol dimethacrylate. The liquid crystal composition preferably contains an optically active compound (chiral compound) and a polymerization initiator. Each component may contain one or more of them alone. For example, the liquid crystal compound may be used in combination with a polymerizable liquid crystal compound and a non-polymerizable liquid crystal compound. In addition, a low molecular liquid crystal compound and a high molecular liquid crystal compound may also be used in combination. In order to improve the uniformity of the orientation of various liquid crystal compounds, the coating suitability of the liquid crystal composition and the strength of the resulting coating film, the liquid crystal composition may contain more than one of various additives selected from horizontal orientation agents, anti-uneven agents, anti-cratering agents and polymerizable monomers. In addition, the liquid crystal composition may also optionally contain polymerization inhibitors, antioxidants, ultraviolet absorbers, light stabilizers, colorants and metal oxide microparticles, etc., within the range that does not reduce the optical properties.

(A) Liquid Crystalline Compounds

The liquid crystal compound is preferably a rod-shaped liquid crystal compound. Examples of the rod-shaped liquid crystal compound include rod-shaped nematic liquid crystal compounds. The rod-shaped nematic liquid crystal compound is preferably, for example, azomethine, azoxy, cyanobiphenyl, cyanophenyl ester, benzoate, cyclohexanecarboxylic acid phenyl ester, cyanophenylcyclohexane, cyano-substituted phenylpyrimidine, phenyldioxane, tolan, and alkenylcyclohexylbenzonitrile. In addition, the rod-shaped liquid crystal compound is not only a low molecular weight liquid crystal compound, but also a high molecular weight liquid crystal compound can be used.

Rod-like liquid crystal compounds may be polymerizable or non-polymerizable. Rod-like liquid crystal compounds without polymerizable groups are described in various documents (e.g., Y. Goto et.al., Mol. Cryst. Liq. Cryst. 1995, Vol. 260, pp. 23-28). Polymerizable rod-like liquid crystal compounds can be obtained by introducing polymerizable groups into rod-like liquid crystal compounds. The polymerizable groups include unsaturated polymerizable groups, epoxy groups, and aziridinyl groups (Aziridinyl Group), preferably unsaturated polymerizable groups, and particularly preferably ethylene unsaturated polymerizable groups. The polymerizable groups can be introduced into the molecules of rod-like liquid crystal compounds by various methods. The number of polymerizable groups possessed by the polymerizable rod-like liquid crystal compound is preferably 1 to 6, and more preferably 1 to 3. The polymerizable rod-shaped liquid crystal compound includes, for example, compounds described in Makromol. Chem., Vol. 190, p. 2255 (1989), Advanced Materials, Vol. 5, p. 107 (1993), U.S. Pat. No. 4,683,327, U.S. Pat. No. 5,622,648, U.S. Pat. No. 5,770,107, International Publication No. 95/22586, International Publication No. 95/24455, International Publication No. 97/00600, International Publication No. 98/23580, International Publication No. 98/52905, Japanese Patent Application Publication No. 1-272551, Japanese Patent Application Publication No. 6-16616, Japanese Patent Application Publication No. 7-110469, Japanese Patent Application Publication No. 11-80081, and Japanese Patent Application Publication No. 2001-328973. The rod-like liquid crystal compound may be used in combination of two or more polymerizable rod-like liquid crystal compounds. When two or more polymerizable rod-like liquid crystal compounds are used in combination, the alignment temperature can be lowered.

(B) Alkyl glycol di(meth)acrylate

The liquid crystal composition contains at least one alkyl glycol di(meth)acrylate selected from the group consisting of alkyl glycol diacrylate represented by the following formula (1) and alkyl glycol dimethacrylate represented by the following formula (2) in an amount of 5 to 25 parts by mass relative to 100 parts by mass of the liquid crystal compound. By containing a predetermined amount of alkyl glycol di(meth)acrylate in the liquid crystal composition, an optical laminate having a narrower reflection band can be obtained in comparison with optical laminates having the same maximum reflectivity. Among these alkyl glycol di(meth)acrylates, the alkyl glycol diacrylate represented by the following formula (1) is more preferably used.

(wherein n represents an integer from 4 to 12, and more preferably an integer from 4 to 10).

(wherein n represents an integer from 4 to 12, and more preferably an integer from 4 to 10).

The content of alkyl glycol di(meth)acrylate in the liquid crystal composition is 5 parts by mass or more and 25 parts by mass or less relative to 100 parts by mass of the liquid crystal compound, and the lower limit of the content is preferably 6 parts by mass, more preferably 7 parts by mass, more preferably 8 parts by mass, and even more preferably 10 parts by mass, particularly preferably 12 parts by mass, and most preferably 14 parts by mass. In addition, the upper limit of the content of alkyl glycol di(meth)acrylate is preferably 20 parts by mass relative to 100 parts by mass of the liquid crystal compound. When the content of alkyl glycol di(meth)acrylate is less than 5 parts by mass, the effect of narrowing the reflection band of the light reflecting layer expected by the present invention cannot be obtained. In addition, when the content of alkyl glycol di(meth)acrylate is more than 25 parts by mass, the liquid crystal is not aligned and the cholesterol liquid crystal phase is not shown.

Therefore, by setting the content of the alkyl glycol di(meth)acrylate to 5 parts by mass or more and 20 parts by mass or less, in the obtained light reflecting layer, liquid crystals can be appropriately aligned and the reflection band can be narrowed.

(C) Optically active compounds (chiral agents)

The liquid crystal composition is preferably one that contains an optically active compound in order to exhibit a cholesterol liquid crystal phase. However, in the case where the rod-shaped liquid crystal compound is a molecule having an asymmetric carbon atom, a cholesterol liquid crystal phase can sometimes be stably formed even without adding an optically active compound. The optically active compound can be selected from various generally known chiral agents (for example, as recorded in the Liquid Crystal Device Handbook, Chapter 3, Item 4-3, TN, STN Chiral Agents, Page 199, Japan Society for the Promotion of Science, 142nd Committee, 1989). Optically active compounds generally contain asymmetric carbon atoms, but axial asymmetric compounds or planar asymmetric compounds that do not contain asymmetric carbon atoms can also be used as chiral agents. Examples of axial asymmetric compounds or planar asymmetric compounds include binaphthyl, helicene, paracyclophane, and derivatives thereof. The optically active compound (chiral agent) may also have a polymerizable group. In the case where the optically active compound has a polymerizable group and the rod-shaped liquid crystal compound used in combination also has a polymerizable group, a polymer having a repeating unit derived from the rod-shaped liquid crystal compound and a repeating unit derived from the optically active compound can be formed by the polymerization reaction of the polymerizable optically active compound and the polymerizable rod-shaped liquid crystal compound. In this embodiment, the polymerizable group possessed by the polymerizable optically active compound is preferably the same group as the polymerizable group possessed by the polymerizable rod-shaped liquid crystal compound. Therefore, the polymerizable group of the optically active compound is preferably also an unsaturated polymerizable group, an epoxy group or an aziridine group, more preferably an unsaturated polymerizable group, and particularly preferably an ethylenically unsaturated polymerizable group. In addition, the optically active compound may also be a liquid crystal compound.

Relative to 100 parts by mass of the liquid crystal compound used in combination, the content of the optically active compound contained in the liquid crystal composition is preferably 0.1 parts by mass or more and 20 parts by mass or less, and more preferably 1 parts by mass or more and 10 parts by mass or less. The less the amount of the optically active compound used, the less influence it has on the liquid crystal properties, so it is preferred. Therefore, the optically active compound used as a chiral agent is preferably a compound that exhibits a strong torsion force in a torsion orientation of a desired helical pitch even in a small amount. The chiral agent that exhibits a strong torsion force in this way can be cited, for example, as the chiral agent described in Japanese Patent Publication No. 2003-287623, and it is more preferred to use the chiral agent.

(D) Polymerization initiator

The liquid crystal composition is preferably a polymerizable liquid crystal composition, and it preferably contains a polymerization initiator. In order to cure the applied liquid crystal composition by ultraviolet irradiation, the polymerization initiator used is preferably a photopolymerization initiator that can start polymerization by ultraviolet irradiation. The photopolymerization initiator is not particularly limited, and examples thereof include 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropane-1-one ("Omnirad 907" manufactured by IGM Resins B.V.), 1-hydroxycyclohexylphenyl ketone ("Omnirad 184" manufactured by IGM Resins B.V.), 4-(2-hydroxyethoxy)-phenyl(2-hydroxy-2-propyl)ketone ("Omnirad 2959" manufactured by IGM Resins B.V.), 1-(4-dodecylphenyl)-2-hydroxy-2-methylpropane-1-one ("Darocur 953" manufactured by Merck), 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropane-1-one ("Darocur 1116" manufactured by Merck), 2-hydroxy-2-methyl-1-phenylpropane-1-one ("IGM Resins B.V. "Omnirad 1173"), diethoxyacetophenone and other acetophenone compounds; benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-2-phenylacetophenone (IGM Resins B.V. "Omnirad 651" and other benzoin compounds; benzoylbenzoic acid, benzoylbenzoic acid methyl ester, 4-phenyldiphenyl ketone, hydroxydiphenyl ketone, 4-benzoyl-4'-methyldiphenyl sulfide, 3,3'-dimethyl-4-methoxydiphenyl ketone (Nippon Kayaku "KAYACURE MBP" and other benzophenone compounds; and thioxanthone, 2-chlorothioxanthone (Nippon Kayaku "KAYACURE Thioxanthone compounds such as 2,4-dichlorothioxanthone (KAYACURE CTX"), 2-methylthioxanthone, 2,4-dimethylthioxanthone (KAYACURE RTX manufactured by Nippon Kayaku Co., Ltd.), isopropylthioxanthone, 2,4-dichlorothioxanthone (KAYACURE CTX manufactured by Nippon Kayaku Co., Ltd.), 2,4-diethylthioxanthone (KAYACURE DETX manufactured by Nippon Kayaku Co., Ltd.), and 2,4-diisopropylthioxanthone (KAYACURE DITX manufactured by Nippon Kayaku Co., Ltd.). These photopolymerization initiators may be used alone or in combination of two or more.

The content of the photopolymerization initiator in the liquid crystal composition is not particularly limited, but is preferably 0.5 to 10 parts by mass, and more preferably 2 to 8 parts by mass, based on 100 parts by mass of the polymerizable liquid crystal compound.

When a phenyl ketone compound or the above-mentioned thioxanthone compound is used as a photopolymerization initiator, it is more preferably used in combination with a reaction auxiliary agent in order to promote the photopolymerization reaction. The reaction auxiliary agent is not particularly limited, and examples thereof include amine compounds such as triethanolamine, methyldiethanolamine, triisopropanolamine, n-butylamine, N-methyldiethanolamine, diethylaminoethyl methacrylate, Michler's Ketone, 4,4'-diethylaminobenzophenone, 4-dimethylaminobenzoic acid ethyl ester, 4-dimethylaminobenzoic acid (n-butoxy) ethyl ester, and 4-dimethylaminobenzoic acid isopentyl ester.

The content of the reaction auxiliary agent in the polymerizable liquid crystal composition is not particularly limited, and is preferably used within the range that does not affect the liquid crystal properties of the polymerizable liquid crystal composition, and is preferably 0.5 to 10 parts by mass or less, and more preferably 1 to 8 parts by mass or less, relative to a total of 100 parts by mass of the polymerizable liquid crystal compound. In addition, relative to the content of the above-mentioned photopolymerization initiator, the content of the reaction auxiliary agent is preferably 0.5 times the amount and less than 2 times the amount on a mass basis.

(E) Solvent

The liquid crystal composition preferably contains a solvent. The solvent is not particularly limited as long as it can dissolve the liquid crystal compound, the chiral agent, etc., and examples thereof include methyl ethyl ketone, toluene, methyl isobutyl ketone, cyclopentanone, acetone, and anisole, and cyclopentanone with good solubility is more preferred. In addition, these solvents can be contained in any ratio, and a single solvent or a combination of multiple solvents can also be used. The solvent is dried and removed in a drying area such as an oven or a film coating production line.

(F) Additives

In the liquid crystal composition, the following additives may be further added at any ratio: surface adjusters, defoamers, ultraviolet absorbers, light stabilizers, antioxidants, polymerization inhibitors, crosslinkers, plasticizers, inorganic microparticles, fillers, etc., so that the functions of each additive can be given to the liquid crystal composition. Surface adjusters include fluorine compounds, silicone compounds, acrylic compounds, etc. Ultraviolet absorbers include benzotriazole compounds, diphenyl ketone compounds, triazine compounds, etc. Light stabilizers include hindered amine compounds, benzyl ester compounds, etc., and antioxidants include phenol compounds, etc. Polymerization inhibitors include methoquinone, methyl hydroquinone, hydroquinone, etc., and crosslinkers include polyisocyanates, melamine compounds, etc. Examples of the plasticizer include phthalic acid esters such as dimethyl phthalate or diethyl phthalate, trimellitic acid esters such as tri(2-ethylhexyl) trimellitic acid ester, aliphatic diprotic acid esters such as dimethyl adipate or dibutyl adipate, orthophosphates such as tributyl phosphate or triphenyl phosphate, and acetates such as triacetin or 2-ethylhexyl acetate.

〈Light reflecting layer〉

The light reflecting layer is a cholesterol liquid crystal layer formed by fixing the cholesterol liquid crystal phase of the above-mentioned liquid crystal composition. The helical structure of the light reflecting layer can be a right-handed helical structure having right circularly polarized light reflection ability, or a left-handed helical structure having left circularly polarized light reflection ability, which can be appropriately determined by a person skilled in the art.

The thickness of the light reflecting layer is preferably 0.2 μm to 5.0 μm, more preferably 0.3 μm to 4.0 μm, still more preferably 0.4 μm to 3.0 μm, and particularly preferably 0.5 μm to 2.0 μm. When the thickness of the light reflecting layer is less than 0.2 μm, the reflectivity of the obtained optical laminate may become extremely low. On the other hand, when the thickness of the light reflecting layer exceeds 5.0 μm, the cholesterol liquid crystal is not aligned, and the haze value described later may increase.

The light reflecting layer can be formed by various methods. For example, a method of forming the light reflecting layer by coating a liquid crystal composition can be cited. More specifically, the liquid crystal composition can be coated on a surface of a substrate or an alignment layer provided on the substrate described later, and after the liquid crystal composition is formed into a cholesteric liquid crystal phase, a curing reaction (such as a polymerization reaction, a cross-linking reaction, etc.) is performed to fix the cholesteric liquid crystal phase to form a light reflecting layer.

The light reflecting layer formed by fixing the cholesterol liquid crystal phase has a tendency to deteriorate by irradiation with ultraviolet rays, and the degradation is particularly significant for ultraviolet rays with a wavelength of 380nm or less. Therefore, by adding a material (ultraviolet absorber) that absorbs light in the ultraviolet region to the substrate or at least one layer of the light reflecting layer, or by further laminating a layer containing the material, such as a light absorbing layer, on the light reflecting layer, the degradation of the light reflecting layer can be significantly suppressed.

<Optical laminate>

As shown in Fig. 1 , the optical layered body 1 of the present invention includes a substrate 2 and a light reflecting layer 3. The substrate 2 and the light reflecting layer 3 may be laminated with an adhesive interposed therebetween.

The optical laminate 1 may include two or more light reflecting layers 3. In the case where the optical laminate 1 includes two or more light reflecting layers 3, the two or more light reflecting layers 3 may have different central reflection wavelengths or the same central reflection wavelength. In addition, the spiral directions of the two or more light reflecting layers 3 may be the same or opposite.

The substrate can be provided as the outermost layer on both sides of the light reflecting layer. As long as the substrate is self-supporting, the material and optical properties are not particularly limited. Sometimes, high transparency to ultraviolet rays is required depending on the application. The substrate can be a film or a three-dimensional structure such as a curved surface. The production steps are managed and manufactured in a manner that meets the predetermined optical properties.

The substrate is preferably, for example, a polymer film. Examples of polymer films with high transmittance to visible light include polymer films for various optical films used as components of display devices such as liquid crystal display devices. Examples of such substrates include polyester films such as polyethylene terephthalate (PET), polybutylene terephthalate, and polyethylene naphthalate (PEN); cellulose triacetate films, polycarbonate (PC) films, and polymethyl methacrylate films; and polyolefin films such as polyethylene and polypropylene. Among these, polyethylene terephthalate films, cellulose triacetate films, and polycarbonate films are more preferred. In addition to polymer films, glass substrates and the like can be cited.

In order to more accurately define the orientation direction of the liquid crystal compound in the cholesterol liquid crystal phase, the surface of the substrate may also be oriented. In order to perform the orientation, it is more preferred to perform a grinding and brushing process on the surface of the substrate to form an orientation surface. In addition, as described below, an orientation layer may also be provided on the surface of the substrate.

The alignment layer has the function of more precisely defining the alignment direction of the liquid crystal compound in the cholesterol liquid crystal phase. The alignment layer can be provided by means of abrasion treatment of an organic compound (preferably a polymer), oblique evaporation of an inorganic compound, formation of a layer with micro grooves, etc. In addition, an alignment layer that generates an alignment function by imparting an electric field, imparting a magnetic field, or irradiating light is also known. The alignment layer is preferably formed on the surface of a polymer film by abrasion treatment.

The alignment layer preferably has a certain degree of adhesion to any of the adjacent light reflecting layer (cholesterol liquid crystal layer) and the substrate. In the case of preparing a laminate while peeling the substrate from the light reflecting layer, a weak peeling force of a peelable degree must be inserted at any interface of the light reflecting layer/alignment layer/substrate. The peeled interface can be any interface, but since the optical laminate is prepared in a subsequent step, it is more preferred to peel at the interface between the light reflecting layer and the alignment layer.

The material used for the alignment layer is preferably a polymer of an organic compound, and generally a polymer that can be cross-linked by itself or a polymer that can be cross-linked by a cross-linking agent is used. In addition, a polymer having dual functions can also be used. Examples of polymers include: polymethyl methacrylate, acrylic acid/methacrylic acid copolymer, styrene/maleimide copolymer, polyvinyl alcohol or denatured polyvinyl alcohol, poly(N-hydroxymethyl acrylamide), styrene/vinyl toluene copolymer, chlorosulfonated polyethylene, nitrocellulose, polyvinyl chloride, chlorinated polyolefin, polyester, polyimide, polyamide, vinyl acetate/vinyl chloride copolymer, ethylene/vinyl acetate copolymer, carboxymethyl cellulose, gelatin, polyvinyl alcohol, denatured polyvinyl alcohol, polyethylene, polypropylene or polycarbonate, or compounds such as silane coupling agents. Examples of more preferred polymers are water-soluble polymers such as poly(N-hydroxymethyl acrylamide), carboxymethyl cellulose, gelatin, polyvinyl alcohol or denatured polyvinyl alcohol, and gelatin, polyvinyl alcohol or denatured polyvinyl alcohol can also be mentioned. The thickness of the alignment layer is preferably above 0.1 μm and below 5.0 μm.

When the optical laminate is used in an eye device that imparts creativity, the optical laminate has a selected central reflection wavelength (hereinafter referred to as "central reflection wavelength") within the range of 400 nm to 900 nm. The lower limit of the central reflection wavelength is preferably 420 nm or more, and more preferably 450 nm or more. In addition, the upper limit of the central reflection wavelength is preferably 850 nm or less, and more preferably 750 nm or less.

The maximum reflectivity of the optical laminate for incident light is preferably 90% or less, more preferably 70% or less, even more preferably 50% or less, particularly preferably 45% or less, and most preferably 40% or less. In addition, the lower limit of the maximum reflectivity of the optical laminate for incident light is 10%, more preferably 15%, and more preferably 20%. By making the maximum reflectivity 10% or more, creativity can be imparted to the ophthalmic device. The incident light is light that is incident vertically on the optical laminate. In addition, the maximum reflectivity means the maximum reflectivity of the optical laminate in the wavelength region of 400nm to 900nm, and the minimum reflectivity means the minimum reflectivity of the optical laminate in the wavelength region of 400nm to 900nm.

In addition, the "central reflection wavelength" means the average wavelength of the wavelength on the short wavelength side corresponding to 80% of the maximum reflectivity of the optical laminate and the wavelength on the long wavelength side. For example, when the maximum reflectivity of the optical laminate is 60%, the wavelength on the short wavelength side showing a reflectivity of 48% corresponding to 80% is set to λ1, and the wavelength on the long wavelength side is set to λ3, and the central reflection wavelength (λ2) is calculated by the following formula (3).

(λ1+λ3)/2＝λ2 (3)

In addition, a reflection band (λ4) corresponding to the difference between the wavelength (λ3) on the long wavelength side and the wavelength (λ1) on the short wavelength side is calculated by the following formula (4).

(λ3-λ1)＝λ4 (4)

The reflection band of the optical laminate differs depending on the reflection wavelength. Generally, the reflection band tends to be narrower as the wavelength region becomes shorter, and wider as the wavelength region becomes longer. When the reflection band exhibited by the optical laminate is expressed in relation to the maximum reflectivity, for example, when the maximum reflectivity is about 20%, the reflection band of the optical laminate is preferably less than 110 nm, when the maximum reflectivity is about 25%, the reflection band of the optical laminate is preferably less than 70 nm, when the maximum reflectivity is about 30%, the reflection band of the optical laminate is preferably less than 60 nm, and when the maximum reflectivity is 35%, the reflection band of the optical laminate is preferably less than 50 nm. This optical laminate has a cholesterol liquid crystal layer formed of a liquid crystal composition containing the above-mentioned alkyl glycol di(meth)acrylate, and has the same maximum reflectivity, and has a reflection band narrower by, for example, about 10 to 50 nm when compared with a comparative optical laminate having a cholesterol liquid crystal layer formed of a liquid crystal composition not containing alkyl glycol di(meth)acrylate.

The haze value of the optical layered body is preferably less than 1.0%, and more preferably 0.5% or less. When the haze value is 1.0% or more, the opacity of the optical layered body increases, and it may not be suitable for use in ophthalmic instruments where transparency is important.

〈Eye equipment〉

The ophthalmic device of the present invention comprises the above-mentioned light reflecting layer or optical laminate. The ophthalmic device can be set to a general structure without particular limitation, for example, an optical film obtained by sandwiching the light reflecting layer or optical laminate between two supporting bodies can be formed into a desired shape and fixed to a frame.

The ophthalmic device may further include a polarizing element layer depending on the application. The polarizing element layer may be laminated on the light reflecting layer, the optical laminate or the support using an adhesive or a bonding agent. Although the laminated structure is not particularly limited, from the viewpoint of durability, it is more preferred to sandwich the polarizing element layer through the support together with the light reflecting layer, the optical laminate or the support.

The support may include resins such as polycarbonate, polyamide and triacetyl cellulose (TAC). In sunglasses or goggles that require impact resistance and heat resistance, polycarbonate is preferably used as the support, and aromatic polycarbonate composed of bisphenol A is more preferably used. The total light transmittance of the support is preferably 70% or more, more preferably 80% or more, and more preferably 85% or more. With such a high total light transmittance, it becomes easy to ensure visibility. In addition, in the case where the optimum processing temperature of the polarizing element layer is low, it is more preferable to select materials such as aromatic polycarbonate, PCC composition (all-alicyclic polyester composition), polyamide with a glass transition temperature of 130°C or less.

In order to laminate with high adhesion to each other, the support and the light reflecting layer or the optical laminate are preferably clamped via an adhesive layer. The adhesive layer can use any adhesive of a hot melt adhesive and a hardening adhesive. Generally, hardening adhesives include acrylic resin materials, urethane resin materials, polyester resin materials, melamine resin materials, epoxy resin materials, silicone materials, etc., and in particular, from the perspective of excellent adhesion or processability during bending, a two-liquid type thermosetting urethane resin composed of a polyurethane prepolymer as an urethane resin material and a hardener is more preferably used.

The eyewear can be, for example, sunglasses, goggles, helmet goggles, etc. The manufacturing method of the eyewear is not particularly limited. For example, in the case where the eyewear is sunglasses, the optical film obtained above is bored into a desired shape and then subjected to bending. The bending method is not particularly limited, and it only needs to be processed through a step that can give a shape to the spherical or aspherical surface according to the purpose. The resin can also be further injected into the bent product. At this time, it also has the advantage that the uneven thickness of the optical film will not be observed. In lenses that do not have focal refractive power, it is also effective for improving impact resistance, appearance, and eye fatigue. In order to prevent the appearance from being deteriorated due to the difference in refractive index, the injected resin is preferably made of the same material as the layer in contact with the injected resin. A hard coating, an anti-reflection film, etc. can be appropriately formed on the surface, and then fixed to the frame by rounding, opening holes, screw locking, etc., so that sunglasses can be manufactured.

According to the above-mentioned embodiment, the present invention relates to the following [1] to [7].

[1]

A liquid crystal composition comprising: a liquid crystal compound, and

At least one alkyl glycol di(meth)acrylate selected from the group consisting of an alkyl glycol diacrylate represented by the following formula (1) and an alkyl glycol dimethacrylate represented by the following formula (2);

The content of the alkyl glycol di(meth)acrylate is 5 parts by mass or more and 25 parts by mass or less relative to 100 parts by mass of the liquid crystal compound.

(wherein n represents an integer from 4 to 12),

(wherein n represents an integer from 4 to 12).

[2]

The liquid crystal composition as described in the above [1], wherein the alkyl glycol di(meth)acrylate contains an alkyl glycol diacrylate represented by the above formula (1).

[3]

A light reflecting layer comprising a cholesteric liquid crystal layer formed by fixing the cholesteric liquid crystal phase of the liquid crystal composition described in [1] or [2] above.

[4]

An optical layered body comprises the light reflecting layer according to [3] above and a substrate.

[5]

The optical layered body as described in the above [4], wherein the haze value (Hz) is less than 1.0%.

[6]

An ophthalmic device comprising the light reflecting layer described in [3] above.

[7]

An ophthalmic device comprising the optical layered body described in [4] or [5] above.

[Example]

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to these examples without departing from the gist of the present invention. In addition, the room temperature was set to be within the range of 20°C ± 5°C unless otherwise specified.

[Examples 1 to 5]

<1> Preparation of liquid crystal composition (coating liquid)

A coating liquid R1 having a composition shown in the following Table 1 was prepared. In addition, the unit in Table 1 is part by mass.

[Table 1]

<2> Fabrication of light reflecting layer and optical laminate

Each cholesteric liquid crystal coating film (light reflecting layer) was prepared using coating liquid R1 by the following procedure: A brushed PET film without a primer layer (manufactured by Toyobo Industries, Ltd., "trade name A4100", thickness 50 μm) was used as a substrate for each light reflecting layer.

(1) Using a wire bar, the coating liquid R1 was applied on a PET film at room temperature so that the light reflecting layer had a thickness shown in Table 2.

(2) Each coating solution was heated at 80° C. for 3 minutes to remove the solvent and form a cholesteric liquid crystal phase. Then, a high-pressure mercury lamp (“HX4000L” manufactured by Harison Toshiba Lighting Co., Ltd.) was set at 120 W output and UV was irradiated for 5 to 10 seconds to produce an optical laminated body having a cholesteric liquid crystal coating film (cholesteric liquid crystal layer) in which a cholesteric liquid crystal phase having a right-handed helical structure was fixed on a PET film.

(3) The reflection spectrum of each optical layered body produced was measured using a spectrophotometer ("MPC-3100" manufactured by Shimadzu Corporation) to obtain the central reflection wavelength, maximum reflectivity and reflection band. In addition, the haze value of each optical layered body was evaluated using a haze meter manufactured by Nippon Denshoku Co., Ltd.

[Examples 6 to 10]

<1> Preparation of liquid crystal composition (coating solution)

A coating liquid R2 having the composition shown in Table 1 was prepared.

<2> Fabrication of light reflecting layer and optical laminate

By the same procedure as in Examples 1 to 5, coating liquid R2 was applied on the PET film instead of coating liquid R1 so that the light reflecting layer had the thickness shown in Table 2, to produce each light reflecting layer in which the cholesterol liquid crystal phase of the right-handed helical structure was fixed, and optical laminates having each light reflecting layer provided on the PET film were produced. The reflection spectrum of each produced optical laminate was measured, and the central reflection wavelength, maximum reflectivity and reflection band were obtained. In addition, the haze value of each optical laminate was evaluated using a haze meter manufactured by Nippon Denshoku Co., Ltd.

[Comparative Examples 1 to 5]

<1> Preparation of liquid crystal composition (coating liquid)

A coating liquid R3 having the composition shown in Table 1 was prepared.

<2> Preparation of light reflecting layer and optical laminate

By the same procedure as in Examples 1 to 5, coating liquid R3 was applied on the PET film instead of coating liquid R1 so that the light reflecting layer had the thickness shown in Table 2, to produce each light reflecting layer in which the cholesterol liquid crystal phase of the right-handed helical structure was fixed, and optical laminates having each light reflecting layer provided on the PET film were produced. The reflection spectrum of each produced optical laminate was measured, and the central reflection wavelength, maximum reflectivity and reflection band were obtained. In addition, the haze value of each optical laminate was evaluated using a haze meter manufactured by Nippon Denshoku Co., Ltd.

[Comparative Examples 6 to 8]

<1> Preparation of liquid crystal composition (coating solution)

A coating liquid R4 having the composition shown in Table 1 was prepared.

<2> Formation of light reflecting layer and optical laminate

By the same procedure as in Examples 1 to 5, coating liquid R4 was applied on the PET film instead of coating liquid R1 so that the light reflecting layer had the thickness shown in Table 2, to produce each light reflecting layer in which the cholesterol liquid crystal phase of the right-handed helical structure was fixed, and optical laminates having each light reflecting layer provided on the PET film were produced. The reflection spectrum of each produced optical laminate was measured, and the central reflection wavelength, maximum reflectivity and reflection band were obtained. In addition, the haze value of each optical laminate was evaluated using a haze meter manufactured by Nippon Denshoku Co., Ltd.

[Examples 11 to 12]

<1> Preparation of liquid crystal composition (coating solution)

A coating liquid R5 having the composition shown in Table 1 was prepared.

<2> Formation of light reflecting layer and optical laminate

By the same procedure as in Examples 1 to 5, coating liquid R5 was applied on the PET film instead of coating liquid R1 so that the light reflecting layer had the thickness shown in Table 2, to produce each light reflecting layer in which the cholesterol liquid crystal phase of the right-handed helical structure was fixed, and optical laminates having each light reflecting layer provided on the PET film were produced. The reflection spectrum of each produced optical laminate was measured, and the central reflection wavelength, maximum reflectivity and reflection band were obtained. In addition, the haze value of each optical laminate was evaluated using a haze meter manufactured by Nippon Denshoku Co., Ltd.

[Examples 13 to 14]

<1> Preparation of liquid crystal composition (coating liquid)

A coating liquid R6 having the composition shown in Table 1 was prepared.

<2> Formation of light reflecting layer and optical laminate

By the same procedure as in Examples 1 to 5, coating liquid R6 was applied on the PET film instead of coating liquid R1 so that the light reflecting layer had the thickness shown in Table 2, to produce each light reflecting layer in which the cholesterol liquid crystal phase of the right-handed helical structure was fixed, and optical laminates having each light reflecting layer provided on the PET film were produced. The reflection spectrum of each produced optical laminate was measured, and the central reflection wavelength, maximum reflectivity and reflection band were obtained. In addition, the haze value of each optical laminate was evaluated using a haze meter manufactured by Nippon Denshoku Co., Ltd.

[Example 15]

<1> Preparation of liquid crystal composition (coating solution)

A coating liquid R7 having the composition shown in Table 1 was prepared.

<2> Formation of light reflecting layer and optical laminate

By the same procedure as in Examples 1 to 5, coating liquid R7 was applied on the PET film instead of coating liquid R1 so that the light reflecting layer had the thicknesses shown in Table 2, thereby producing a light reflecting layer in which a cholesterol liquid crystal phase having a right-handed helical structure was fixed, and an optical laminate having each light reflecting layer arranged on the PET film was produced.

The maximum reflectivity, central reflection wavelength, reflection band, thickness and haze value of each optical laminate produced in Examples 1 to 15 and Comparative Examples 1 to 5 are shown in Table 2. In addition, a scatter diagram prepared with the maximum reflectivity and reflection band in each optical laminate obtained in Examples 1 to 5 and Comparative Examples 1 to 5 as axes is shown in FIG2, and the spectral data of the optical laminate produced in each Example and Comparative Example are shown in FIGS. 3 to 22, respectively.

[Table 2]

As shown in Table 2 and FIG. 2 , the optical laminates of Examples 1 to 5 have a reflection band narrower by about 10 to 50 nm than the optical laminates of Comparative Examples 1 to 5 when the maximum reflectance is the same, which means that the reflection band of the optical laminate obtained by adding a predetermined amount of alkyl glycol di(meth)acrylate to the liquid crystal composition can be narrowed. In addition, any of the optical laminates of Examples 1 to 10 exhibits a low haze value of 0.5% or less.

On the other hand, in Comparative Examples 6 to 8, in which about 26.7% by mass of alkyl glycol di(meth)acrylate was added to 100 parts by mass of the liquid crystal compound, poor alignment of the liquid crystal was caused, and the reflective properties unique to the cholesteric liquid crystal phase were not exhibited.

In addition, the optical laminates of Examples 11 to 15 using alkyl glycol diacrylates with different carbon numbers also have a reflection band narrower by about 10 to 50 nm than the optical laminates of Comparative Examples 1 to 5 having the same maximum reflectance, indicating that the reflection band can be narrowed even when alkyl glycol diacrylates with different carbon numbers are used. In addition, any of the optical laminates of Examples 11 to 15 exhibited a low haze value of less than 0.5%.

As described above, the optical layered bodies of Examples 1 to 15 have a narrow reflection band and exhibit a low haze value of less than 0.5%, and therefore are suitable for use in optical members.

[Industrial Applicability]

The present invention relates to a liquid crystal composition that can form an optical laminate having a light reflecting layer with a fixed cholesterol liquid crystal phase and a narrow reflection band, as well as a light reflecting layer and an optical laminate formed by the liquid crystal composition. The light reflecting layer and the optical laminate are mainly suitable for use in eyewear (sunglasses, goggles, goggles for helmets, etc.).

Description of Reference Numerals

1. Optical laminate

2. Substrate

3 light reflecting layers.

Claims (7)

1. A liquid crystal composition comprising: liquid crystal compound

At least 1 alkyl glycol di (meth) acrylate selected from the group consisting of an alkyl glycol diacrylate represented by the following formula (1) and an alkyl glycol dimethacrylate represented by the following formula (2);

The content of the alkyl glycol di (meth) acrylate is 5 to 25 parts by mass based on 100 parts by mass of the liquid crystal compound,

Wherein n represents an integer of 4 to 12,

Wherein n represents an integer of 4 to 12.

2. The liquid crystal composition according to claim 1, wherein the alkyl glycol di (meth) acrylate contains an alkyl glycol diacrylate represented by the formula (1).

3. A light reflection layer comprising a cholesteric liquid crystal layer obtained by fixing a cholesteric liquid crystal phase of the liquid crystal composition according to claim 1 or 2.

4. An optical laminate comprising the light reflecting layer according to claim 3 and a substrate.

5. The optical stack of claim 4 having a haze value (Hz) of less than 1.0%.

6. An ophthalmic device comprising the light reflecting layer according to claim 3.

7. An ophthalmic device comprising the optical laminate of claim 4.