Composition, method for producing cholesteric liquid crystal layer, cholesteric liquid crystal layer, and reflective film

Abstract

The first problem addressed by the present invention is to provide a composition which is capable of forming a cholesteric liquid crystal layer that has excellent reflectance and small film thickness unevenness, while having an area of a cholesteric liquid crystal phase that has a right-handed helical direction and an area of a cholesteric liquid crystal phase that has a left-handed helical direction in the thickness direction. The second problem addressed by the present invention is to provide a cholesteric liquid crystal layer, a method for producing a cholesteric liquid crystal layer, and a reflective film each pertaining to the composition.　A composition according to the present invention contains a polymerizable liquid crystal compound, a chiral agent A the helical twisting power of which is changed by exposure to light, a chiral agent B the helical twisting power of which is not changed by exposure to light, and a photopolymerization initiator. This composition satisfies the following formula (F1).　Formula (F1): 0.90 < -2Zb / (X + Y)a < 1.10

Description

Composition, method for producing cholesteric liquid crystal layer, cholesteric liquid crystal layer, and reflective film

[0001] The present invention relates to a composition, a method for producing a cholesteric liquid crystal layer, a cholesteric liquid crystal layer, and a reflective film.

[0002] Recently, a so-called head-up display system has been developed as one type of in-vehicle display, which projects various information as an image onto the windshield glass or the like using a projector to convey the information to the driver.

[0003] A known head-up display system is one in which a reflective film including a cholesteric liquid crystal layer that selectively reflects circularly polarized light is incorporated into a windshield glass. Furthermore, in order to achieve a reflection spectrum with a wide reflection band across the visible range, the cholesteric liquid crystal layer is often constructed by laminating multiple cholesteric liquid crystal layers with different central reflection wavelengths (in other words, different helical pitches derived from the liquid crystal compounds).

[0004] For example, Patent Document 1 discloses an optical film including a light-reflecting layer R made of a cholesteric liquid crystal layer having a right-handed helical direction, a light-reflecting layer L made of a cholesteric liquid crystal layer having a left-handed helical direction, and a polarizing element layer. In Patent Document 1, the optical film is produced by bonding the light-reflecting layer R and the light-reflecting layer L together with an adhesive.

[0005] International Publication No. 2016 / 002582

[0006] The present inventors attempted to form a reflective layer by laminating a cholesteric liquid crystal layer having a right-handed helical direction and a cholesteric liquid crystal layer having a left-handed helical direction with reference to the optical film described in Patent Document 1, but found that unevenness in film thickness was likely to occur, and clarified the need for improvement. In addition, high reflectivity is also required as a basic performance of the reflective layer itself.

[0007] Therefore, an object of the present invention is to provide a composition capable of forming a cholesteric liquid crystal layer having excellent reflectivity and minimal thickness unevenness. More specifically, an object of the present invention is to provide a composition capable of forming a cholesteric liquid crystal layer having excellent reflectivity and minimal thickness unevenness, and having a cholesteric liquid crystal phase domain having a right-handed helical direction and a cholesteric liquid crystal phase domain having a left-handed helical direction along the thickness direction. Another object of the present invention is to provide a cholesteric liquid crystal layer, a method for producing a cholesteric liquid crystal layer, and a reflective film related to the composition.

[0008] The present inventors have found that the above problems can be solved by the following configuration.

[0009] [1] A composition comprising a polymerizable liquid crystal compound, a chiral agent A whose helical twisting power changes upon exposure, a chiral agent B whose helical twisting power does not change upon exposure, and a photopolymerization initiator, and satisfying formula (F1) described below. [2] The composition according to [1], wherein the chiral agent A is a compound represented by formula (1) described below. [3] The composition according to [1] or [2], wherein the chiral agent A's helical twisting power changes upon irradiation with light having a wavelength of 350 nm or more. [4] The composition according to any one of [1] to [3], wherein the polymerizable liquid crystal compound has a Δn of 0.15 or more. [5] A method for producing a cholesteric liquid crystal layer, comprising, in this order: Step 1: forming a composition layer of the composition according to any one of [1] to [4] on a support; Step 2: orienting the polymerizable liquid crystal compound in the composition layer; Step 3: irradiating the composition layer from the side opposite the support with light of a wavelength capable of changing the helical twisting power of the chiral dopant A under conditions of an oxygen concentration of 1% by volume or more; Step 4: heating the composition layer; and Step 5: curing the composition layer to fix the alignment state of the polymerizable liquid crystal compound. [6] A cholesteric liquid crystal layer formed using the composition according to any one of [1] to [4]. [7] A reflective film having the cholesteric liquid crystal layer according to [6].

[0010] According to the present invention, there is provided a composition capable of forming a cholesteric liquid crystal layer having excellent reflectivity, minimal thickness unevenness, and having a cholesteric liquid crystal phase domain having a right-handed helical direction and a cholesteric liquid crystal phase domain having a left-handed helical direction along the thickness direction. Furthermore, according to the present invention, there are provided a cholesteric liquid crystal layer, a method for producing a cholesteric liquid crystal layer, and a reflective film, each of which is related to the composition.

[0011] FIG. 1 is a schematic diagram for explaining the mechanism of action of the composition of the present invention and an example of an embodiment thereof. FIG. 2 is a schematic diagram for explaining the exposure treatment of Test 1. FIG. 3 is a schematic diagram for explaining the exposure treatment of Test 1. FIG. 4 is a schematic diagram for explaining an example of an embodiment of the composition of the present invention. FIG. 5 is a schematic diagram for explaining an example of an embodiment of the composition of the present invention. FIG. 6 is a schematic diagram for explaining the manufacturing method of the present invention.

[0012] The present invention will be described in detail below. The following description of the constituent elements may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. In this specification, "(meth)acrylate" refers to both acrylate and methacrylate, "(meth)acryloyl group" refers to both acryloyl group and methacryloyl group, and "(meth)acrylic" refers to both acrylic and methacrylic.

[0013] In the present specification, when a group (atomic group) is represented without specifying whether it is substituted or unsubstituted, it encompasses both unsubstituted and substituted groups. For example, the term "alkyl group" encompasses not only alkyl groups without a substituent (unsubstituted alkyl groups) but also alkyl groups with a substituent (substituted alkyl groups).

[0014] In this specification, the bonding direction of a divalent group (e.g., —CO—O—) is not limited unless otherwise specified. For example, when Y is —CO—O— in a compound represented by the formula “X-Y-Z,” the compound may be “X-O-CO-Z” or “X-CO-O-Z.”

[0015] In this specification, unless otherwise specified, the term "light" irradiated during exposure treatment refers to actinic rays or radiation, such as the bright line spectrum of a mercury lamp, far ultraviolet light typified by excimer lasers, extreme ultraviolet light (EUV light: Extreme Ultraviolet), X-rays, ultraviolet light, and electron beams (EB). Of these, ultraviolet light is preferred. In this specification, unless otherwise specified, "light irradiation" and "exposure" have the same meaning.

[0016] In the description of the present specification, "light" other than that of the exposure treatment refers to visible light and natural light (unpolarized light) unless otherwise specified.

[0017] In this specification, "visible light" refers to light in the wavelength range of 380 to 780 nm. In addition, in this specification, unless otherwise specified, the measurement wavelength is 550 nm. Of visible light, light in the wavelength range of 420 to 490 nm is blue (B) light, light in the wavelength range of 495 to 570 nm is green (G) light, and light in the wavelength range of 620 to 750 nm is red (R) light. In this specification, "invisible light" refers to light in the wavelength range of less than 380 nm or more than 780 nm.

[0018] In this specification, the cholesteric liquid crystal phase is a phase having a periodic structure in which liquid crystal compounds are helically aligned, and the twist angle is 360° or more. When liquid crystal compounds are helically aligned in an optically anisotropic layer other than the cholesteric liquid crystal phase, the twist angle is preferably more than 0° and less than 360°.

[0019] In this specification, "increase and decrease in helical twisting power" refers to an increase or decrease when the initial helical direction of the chiral agent (before light irradiation (exposure)) is considered to be "positive." Therefore, even when the helical twisting power continues to decrease upon light irradiation and exceeds 0, causing the helical direction to become "negative" (i.e., when a helical twist in the opposite direction to the initial helical direction is induced), the chiral agent falls under the category of "a chiral agent whose helical twisting power decreases." Furthermore, the helical direction is determined as right-handed or left-handed with reference to the surface opposite to the observation side of the cholesteric liquid crystal layer (a composition layer in which liquid crystal compounds are oriented in a cholesteric liquid crystal phase).

[0020] In this specification, terms relating to angles such as "angles expressed by specific numerical values," "parallel," "horizontal," "vertical," and "orthogonal" include a generally acceptable error range in the relevant technical field unless otherwise specified. Specifically, this means that the error is within a range of ±10° or less from the exact angle. The error from the exact angle is preferably ±7° or less, and more preferably ±5° or less.

[0021] In this specification, the terms "same" and "entire surface" include a generally acceptable margin of error in the relevant technical field, unless otherwise specified.

[0022] In this specification, "visible light transmittance" refers to the visible light transmittance for an A light source as defined in JIS (Japanese Industrial Standards) R 3212:2015 (Test Methods for Automotive Safety Glass). That is, the transmittance is determined by measuring the transmittance at each wavelength in the wavelength range of 380 to 780 nm using a spectrophotometer with an A light source, multiplying the transmittance at each wavelength by a weighting factor obtained from the wavelength distribution and wavelength interval of the CIE (Commission Internationale de l'Eclairage) photopic standard relative luminosity factor, and averaging the results. When simply referring to "reflected light" or "transmitted light," this term is used to include scattered light and diffracted light. In this specification, the in-plane retardation (in-plane phase difference) is a value measured using an AxoScan manufactured by Axometrics. Unless otherwise specified, the measurement wavelength is 550 nm. The in-plane retardation is a value measured by irradiating light with a wavelength within the visible light wavelength range in the direction normal to the film.

[0023] In this specification, the "solid content" of a composition refers to components that form a cholesteric liquid crystal layer formed using the composition, and when the composition contains a solvent (organic solvent, water, etc.), it refers to all components excluding the solvent. Furthermore, liquid components that form a cholesteric liquid crystal layer are also considered to be solid contents.

[0024] [Composition] The composition of the present invention comprises a polymerizable liquid crystal compound, a chiral agent A whose helical twisting power (hereinafter also referred to as "HTP") changes upon exposure, a chiral agent B whose helical twisting power does not change upon exposure, and a photopolymerization initiator, and satisfies the following formula (F1): Formula (F1): 0.90 < -2Zb / (X+Y)a < 1.10 In the formula, X is the helical twisting power of the chiral agent A before exposure. Y is the helical twisting power of the chiral agent A obtained by the following Test 1. Z is the helical twisting power of the chiral agent B. a is the concentration of the chiral agent A relative to the polymerizable liquid crystal compound. b is the concentration of the chiral agent B relative to the polymerizable liquid crystal compound. However, X, Y, and Z in formula (F1) are negative values ​​when a right-handed helix is ​​induced, and are positive values ​​when a left-handed helix is ​​induced. The unit of the helical induction force is μm. －１ The unit of the concentration is % by mass. Test 1: The chiral agent A is exposed to light using a light-emitting diode having an emission peak wavelength of 365 nm, the helical twisting power of the chiral agent A is measured for each exposure dose, and the helical twisting power at the exposure dose at which there is no longer any change in the helical twisting power is defined as Y.

[0025] When the composition of the present invention is applied to the method for producing a cholesteric liquid crystal layer described below (hereinafter also referred to as the "production method of the present invention"), it is possible to form a cholesteric liquid crystal layer having a cholesteric phase region having a right-handed helical direction and a cholesteric phase region having a left-handed helical direction along the thickness direction. The cholesteric liquid crystal layer formed in this manner has less thickness unevenness than when a cholesteric liquid crystal layer is formed by laminating a cholesteric liquid crystal layer having a right-handed helical direction and a cholesteric liquid crystal layer having a left-handed helical direction. Furthermore, in the cholesteric liquid crystal layer formed using the composition of the present invention, as described below, the helical pitches of the cholesteric phase having the right-handed helical direction and the cholesteric phase having the left-handed helical direction are approximately the same (the selective reflection wavelengths of the cholesteric liquid crystal layer before and after exposure are approximately the same), and therefore the reflectivity is also excellent.

[0026] The presumed mechanism of action of the composition of the present invention will be explained below. After explaining the presumed mechanism of action of the composition of the present invention, the characteristics of the production method of the present invention will also be explained.

[0027] [Mechanism of Action of the Composition of the Present Invention] First, the HTP (helix twisting power) of the chiral agent will be described below. The HTP of the chiral agent is a factor that indicates the helical orientation ability, which is expressed by the following formula (F2): HTP = 1 / (helical pitch length (unit: μm) × concentration of the chiral agent relative to the liquid crystal compound (mass %)) [μm －１ The helical pitch length refers to the length of the pitch P (=helical period) of the helical structure of a cholesteric liquid crystal phase, and can be measured by the method described on page 196 of Liquid Crystal Handbook (published by Maruzen Co., Ltd.). In other words, when it is desired to adjust the pitch P of a cholesteric liquid crystal phase to a certain length, the concentration (amount added) of a chiral agent with a large HTP is reduced, and conversely, when a chiral agent with a small HTP is used, the concentration (amount added) is increased.

[0028] The HTP of the chiral dopant can also be expressed by the following formula (F3): HTP = (average refractive index of the liquid crystal compound) / {(concentration of the chiral dopant relative to the liquid crystal compound (mass%)) × (center reflection wavelength (nm))} [μm －１ ]

[0029] When two or more chiral agents are contained in the composition, the pitch P of the cholesteric liquid crystal phase is determined by the sum of the products of the HTPs determined for each chiral agent contained in the composition and the concentrations (amounts added). The HTPs induced by two or more chiral agents (hereinafter referred to as "average HTP (μm －１ ") represents the sum of the values ​​obtained by dividing the product of the HTP of each chiral agent contained in the composition and the concentration (% by mass) of each chiral agent contained in the composition relative to the liquid crystal compound by the total concentration (% by mass) of the chiral agents relative to the liquid crystal compound. For example, when two types of chiral agents (e.g., chiral agent X and chiral agent Y) are used in combination, it is represented by the following formula (F4). Formula (F4) Average HTP (μm －１ ) = (HTP of chiral agent X (μm －１ ) × concentration of chiral dopant X relative to liquid crystal compound (mass %) + HTP of chiral dopant Y (μm －１ ) × concentration of chiral dopant Y relative to liquid crystal compound (mass %)) / (concentration of chiral dopant X relative to liquid crystal compound (mass %) + concentration of chiral dopant Y relative to liquid crystal compound (mass %)) However, in the above formulas (F1) to (F4), when the helical direction of the chiral dopant is right-handed, the HTP is a negative value. When the helical direction of the chiral dopant is left-handed, the HTP is a positive value. That is, for example, when the HTP is 10 μm －１ In the case of the chiral agent, when the helical direction of the helix induced by the chiral agent is left-handed, the HTP is set to 10 μm －１ On the other hand, when the helical direction of the helix induced by the chiral agent is right-handed, the HTP is −10 μm －１ It is expressed as:

[0030] The composition of the present invention contains a chiral agent A whose HTP changes upon exposure and a chiral agent B whose HTP does not change upon exposure, and the HTPs and concentrations of the chiral agents A and B satisfy formula (F1). When a composition layer formed from the composition of the present invention is subjected to heat aging, the helical structure of a cholesteric liquid crystal layer obtained by subjecting the cholesteric liquid crystal layer to an exposure treatment (the HTP of the chiral agent A is changed by exposure) has a helical structure whose helical direction is reversed from that of the cholesteric liquid crystal layer before exposure, although the helical pitch remains almost unchanged.

[0031] Hereinafter, the above-mentioned mechanism of action will be explained using as an example a cholesteric liquid crystal layer formed from the composition of the present invention containing chiral agents A1 and B1 having predetermined properties. FIG. 1 is a schematic diagram showing the change in helical structure of a cholesteric liquid crystal layer formed from the composition before and after exposure. The change in helical structure can be adjusted by the HTP and concentrations of chiral agents A1 and B1. Chiral agent A1 is a chiral agent A whose HTP decreases upon exposure, and which induces a left-handed helical spiral before and after exposure. The HTP of chiral agent A1 before exposure is determined by the following formula: X １ μm －１ The HTP obtained by Test 1 described later (hereinafter also referred to as "exposure saturation HTP") is １ μm －１ and X １ >Y １ The chiral agent B1 is a chiral agent B whose HTP does not change upon exposure, and which induces a right-handed helical direction before and after exposure. The HTP of the chiral agent B1 in the composition before and after exposure is expressed as Z １ μm －１ The concentration (amount added) of the chiral agent A1 relative to the polymerizable liquid crystal compound is a １ Mass % and concentration (amount added) of chiral agent B1 relative to polymerizable liquid crystal compound b １ The relationship of mass% is X １ a １ Absolute value of Z １ b １ As shown in the left diagram of FIG. 1, in the cholesteric liquid crystal layer before exposure, the chiral dopant A1 is a left-handed helix, so that X １ a １ On the other hand, since the chiral agent B1 is a right-handed helix, Z １ b １ The value of is negative. The sum of both is X １ a １ +Z １ b １and is a positive value. That is, the helical structure of the cholesteric liquid crystal layer before exposure is a left-handed helical structure. The pitch of the helical structure in the cholesteric liquid crystal layer before exposure is X １ a １ +Z １ b １ Next, when the cholesteric liquid crystal layer is subjected to an exposure treatment, the HTP of the chiral dopant A1 changes to Y １ μm －１ By reducing to Y １ a １ Absolute value of < Z １ b １ and Z, which is the sum of the products of the HTP and the concentration of the chiral agent A and the chiral agent B after exposure, １ b １ +Y １ a １ becomes a negative value. In other words, the helical direction of the helical structure induced by the chiral dopant A1 and the chiral dopant B1 is opposite to the helical structure of the cholesteric liquid crystal layer before exposure. The pitch of the helical structure in the cholesteric liquid crystal layer after exposure is Z １ b １ +Y １ a １ Furthermore, the cholesteric liquid crystal layer is represented by the reciprocal of X １ a １ +Z １ b １ =-(Z １ b １ +Y １ a １ ) and shows the same helical pitch before and after exposure. Expanding the above formula, 1 = -2Z １ b １ / (X １ +Y １ ) a １ In other words, when the helical pitch is the same before and after exposure, the above relational expression is satisfied. １ b １ / (X １ +Y １ ) a １If the ratio is less than 1.10, the deviation in the pitch of the helical structure of the cholesteric liquid crystal layer before and after exposure is small (the selective reflection wavelength of the cholesteric liquid crystal layer before and after exposure is almost the same), and it has been found that when a cholesteric liquid crystal layer is formed by applying the manufacturing method of the present invention described below, the reflectance is excellent.

[0032] [Characteristics of the Manufacturing Method of the Present Invention] The composition of the present invention described above is preferably used in the manufacturing method of the present invention. As will be described in detail later, in the manufacturing method of the present invention, first, a composition layer formed from the composition of the present invention is formed on a support (Step 1), and the polymerizable liquid crystal compound in the composition layer is aligned to form a cholesteric liquid crystal phase (Step 2). In Step 3, the oxygen concentration is low in a portion of the support-side region of the composition layer, and high in another portion of the surface opposite the support side. Therefore, when such a composition layer is irradiated with light of a wavelength capable of changing the HTP of chiral agent A, a change in the HTP of chiral agent A (e.g., photoisomerization or photodimerization) progresses in the region with a high oxygen concentration, but polymerization of the polymerizable components (polymerizable liquid crystal compounds and, when chiral agents A and B are polymerizable chiral agents, this corresponds to polymerizable chiral agents A and B) is difficult to proceed with due to oxygen inhibition, whereas the polymerization reaction of the polymerizable components proceeds more easily in the region with a low oxygen concentration. Furthermore, in regions with low oxygen concentrations, although changes in the HTP of chiral agent A (e.g., photoisomerization or photodimerization) occur, the rate of the polymerization reaction is faster, and as a result, the orientation state of the polymerizable liquid crystal compound is fixed by polymerization before a change in the orientation state of the polymerizable liquid crystal compound occurs due to a change in the HTP of chiral agent A. Then, by the reorientation treatment in step 4 and the curing treatment in step 5, the orientation state of the liquid crystal compound is reoriented in regions where the oxygen concentration was high and the polymerization reaction did not proceed easily in step 3, and is further fixed by polymerization. As a result, a cholesteric liquid crystal layer is formed along the thickness direction of the composition layer, having two cholesteric liquid crystal phases with approximately the same helical pitch but different helical directions. In other words, when the composition of the present invention containing the chiral agent A1 and the chiral agent B1 having predetermined properties shown as an example in the upper part is applied to the manufacturing method of the present invention, a cholesteric liquid crystal layer is formed which has a cholesteric liquid crystal phase in a helical direction derived from the cholesteric liquid crystal layer before exposure on the support side and a cholesteric liquid crystal phase in a helical direction derived from the cholesteric liquid crystal layer after exposure on the opposite side from the support. Furthermore, the two cholesteric liquid crystal phases formed in the thickness direction have substantially the same helical pitch.

[0033] [Specific Procedure for Test 1] Hereinafter, an example of a specific procedure for measuring the post-exposure HTP (exposure saturated HTP, which corresponds to Y in formula (F1)) of the chiral agent A in the composition of the present invention will be described.

[0034] First, a composition for evaluation is prepared by mixing the chiral agent A and the polymerizable liquid crystal compound to be measured, which are contained in the composition of the present invention, with a solvent capable of dissolving the chiral agent A and the polymerizable liquid crystal compound. The obtained evaluation composition is then applied to a support and dried to form a composition layer. An alignment film (e.g., a rubbed alignment film) may be formed on the support. Next, using a light-emitting diode having an emission peak wavelength of 365 nm, the composition layer is subjected to an exposure treatment while increasing the exposure dose. Specifically, the exposure dose is set to 10 mJ / cm. ２ to 10 mJ / cm ２ The composition layer is exposed to light at 15 or more different positions, increasing the exposure dose by 100 mJ / cm. That is, exposure is performed at 15 or more different positions on the surface of the composition layer with different exposure doses. More specifically, as shown in FIG. 2, exposure is performed at different positions on the composition layer, as indicated by the white arrows. In FIG. 2, exposure is performed at three different positions on the composition layer 4 disposed on the support 2. The exposure dose at the leftmost position in FIG. 2 is EmJ / cm. ２ The exposure was performed at a dose of (E+10) mJ / cm ２ The rightmost exposure is performed with an exposure dose of (E+10×2) mJ / cm ２ In this way, the exposure amount is set to 10 mJ / cm for each exposure location. ２ The exposure is performed while increasing the area by 10 mm. The area of ​​the exposed portion is not particularly limited, but may be, for example, about 10 mm long x 20 mm wide. 15 or more exposure locations are used. The upper limit of the number of exposure locations is not particularly limited, but it is preferable to perform exposure until the post-exposure HTP of the chiral agent described below reaches a minimum value (note that this is the minimum value for the chiral agent shown in Figure 3 below, but may also be the maximum value depending on the type of chiral agent), and becomes approximately constant, and more preferably 30 locations or less.

[0035] Next, the composition layer after exposure is heated and aged at 90°C for 1 minute to align the polymerizable liquid crystal compound and bring it into a cholesteric liquid crystal phase state. The heating means is not particularly limited, and an oven can be used, for example. Next, the central reflection wavelength is measured at each exposed location, and the HTP at each exposed location is calculated based on the above formula (F3). Next, a plot diagram is created using the data on the HTP and exposure dose at each exposed location. Specifically, points corresponding to the HTP and exposure dose at each exposed location are plotted on an orthogonal coordinate system with the HTP on the vertical axis and the exposure dose on the horizontal axis. In other words, a graph (HTP-exposure dose correlation curve) is created with the HTP at each exposed location on the vertical axis and the exposure dose at each exposed location on the horizontal axis. The unit of the vertical axis is μm －１ and the unit of exposure is mJ / cm ２ FIG. 3 shows an example of a plot diagram. Each black circle in FIG. 3 corresponds to the result (HTP and exposure dose) at each exposure point. In FIG. 3, for ease of explanation, the number of black circles plotted is less than the actual 15 points. Also, a line may be drawn by connecting each plotted point in the obtained plot diagram.

[0036] As shown in Figure 3, for example, chiral agent A, which can change its HTP by reactions such as photoisomerization and photodimerization, undergoes a large change in HTP at the beginning of exposure, but once a certain exposure dose is reached, the chiral agent reaches reaction equilibrium and the HTP almost stops changing. Here, "no change in HTP" means that the rate of change in HTP between two adjacent plot points is 1% or less. Specifically, adjacent plot points E in Figure 3 Ｘ２ , E Ｘ３ (exposure amount) corresponding to each HTP (each HTP ２、 HTP ３ ), the relationship between |{(HTP ２ -HTP ３ ) / HTP ２}×100|[%] is 1% or less. Therefore, for example, the HTP １ From HTP ２ The rate of change to HTP is more than 1%. ２ From HTP ３When the rate of change to E is less than 1%, the "HTP at the exposure dose when the change in HTP disappears" in Test 1 is Ｘ２ is applicable.

[0037] As a light-emitting diode having an emission peak wavelength of 365 nm, an LED lamp having an emission peak wavelength of 365 nm (manufactured by Acroedge Co., Ltd., "ULW365-21701-5F") available from Acroedge Co., Ltd. can be used.

[0038] Each component that may be contained in the composition of the present invention will be described below.

[0039] [Polymerizable Liquid Crystal Compound] The composition of the present invention contains a polymerizable liquid crystal compound. The polymerizable liquid crystal compound is a liquid crystal compound having a polymerizable group. The polymerizable liquid crystal compound may be either a rod-shaped liquid crystal compound or a discotic liquid crystal compound, but a rod-shaped liquid crystal compound is preferred. Examples of the rod-shaped liquid crystal compound include rod-shaped nematic liquid crystal compounds. Examples of the rod-shaped nematic liquid crystal compound include azomethines, azoxy compounds, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes, and alkenylcyclohexylbenzonitriles. Not only low-molecular-weight liquid crystal compounds but also polymer-molecular-weight liquid crystal compounds can be used.

[0040] A polymerizable liquid crystal compound can be obtained by introducing a polymerizable group into a liquid crystal compound. The type of polymerizable group possessed by the polymerizable liquid crystal compound is not particularly limited, and a functional group capable of an addition polymerization reaction is preferred, a polymerizable ethylenically unsaturated group or a ring-polymerizable group is more preferred, and examples thereof include unsaturated polymerizable groups (e.g., (meth)acryloyl group, vinyl group, styryl group, allyl group, etc.), an epoxy group, and an aziridinyl group. An unsaturated polymerizable group is preferred, and an ethylenically unsaturated polymerizable group is more preferred. The polymerizable group can be introduced into the molecule of the liquid crystal compound by various methods. The number of polymerizable groups possessed by the polymerizable liquid crystal compound is preferably 1 to 6, more preferably 1 to 3, per molecule.

[0041] As the polymerizable liquid crystal compound, there are mentioned Makromol. Chem. , Vol. 190, p. 2255 (1989), Advanced Materials Vol. 5, p. 107 (1993), U.S. Pat. Nos. 4,683,327, 5,622,648, U.S. Pat. No. 5,770,107, WO 95 / 022586, WO 95 / 024455, WO 97 / 00600, WO 98 / 23580, WO 98 / 52905, JP-A-1-272551, JP-A-6-016616, JP-A-7-110469, JP-A-11-080081, and JP-A-2001-328973 include compounds described in the like. In the composition, two or more types of polymerizable liquid crystal compounds may be used in combination.

[0042] The lower limit of Δn of the polymerizable liquid crystal compound is preferably 0.15 or more. The upper limit of Δn is preferably less than 0.55, more preferably 0.50 or less, even more preferably 0.30 or less, and particularly preferably 0.20 or less, in that the composition is more likely to satisfy formula (F1). The Δn of the polymerizable liquid crystal compound is more preferably 0.15 to 0.30, and even more preferably 0.15 to 0.20. The Δn represents the refractive index anisotropy at a wavelength of 550 nm.

[0043] The content of the polymerizable liquid crystal compound in the composition of the present invention is not particularly limited, but is preferably 60% by mass or more, more preferably 70% by mass or more, based on the total solid content of the composition, from the viewpoint of facilitating control of the alignment state of the liquid crystal compound. The upper limit is not particularly limited, but is preferably 99% by mass or less, more preferably 97% by mass or less, even more preferably 95% by mass or less, and particularly preferably 90% by mass or less.

[0044] [Chiral Agent A] The composition of the present invention contains a chiral agent (chiral agent A) whose HTP changes upon exposure. The chiral agent A preferably has a polymerizable group. The type of the polymerizable group is not particularly limited, but a functional group capable of undergoing an addition polymerization reaction is preferred, a polymerizable ethylenically unsaturated group or a ring-polymerizable group is more preferred, and a (meth)acryloyl group, a vinyl group, a styryl group, or an allyl group is even more preferred. When the chiral agent A has a polymerizable group, the number of polymerizable groups contained per molecule is, for example, preferably 1 to 6, more preferably 2 to 4, and even more preferably 2.

[0045] The chiral agent A may be liquid crystalline or non-liquid crystalline. The chiral agent A generally contains an asymmetric carbon atom. The chiral agent A may be an axially asymmetric compound or a planar asymmetric compound that does not contain an asymmetric carbon atom.

[0046] The chiral agent A may be a chiral agent whose HTP increases upon light irradiation (exposure) or a chiral agent whose HTP decreases upon light irradiation (exposure). Among these, a chiral agent whose HTP decreases upon light irradiation is preferred.

[0047] Examples of the chiral agent A include so-called photoreactive chiral agents. A photoreactive chiral agent has a chiral moiety and a photoreactive moiety whose structure changes upon irradiation with light, and is, for example, a compound that significantly changes the twisting power of a liquid crystal compound depending on the amount of irradiation. Examples of photoreactive moieties whose structure changes upon irradiation with light include photochromic compounds (Kingo Uchida, Masahiro Irie, Chemical Industry, Vol. 64, p. 640, 1999; Kingo Uchida, Masahiro Irie, Fine Chemical, Vol. 28(9), p. 15, 1999). The structural change refers to decomposition, addition reaction, isomerization, racemization, [2+2] photocyclization, dimerization, and the like, which occur upon irradiation of the photoreactive moiety with light, and the structural change may be irreversible. Examples of the chiral moiety include the asymmetric carbons described in Hiroyuki Nodaira, Chemistry Review, No. 22, Chemistry of Liquid Crystals, p. 73, 1994.

[0048] As the chiral agent A, a compound having at least a photoisomerization moiety is preferred, and the photoisomerization moiety more preferably has a photoisomerizable double bond.As the photoisomerization moiety having the photoisomerizable double bond, a cinnamoyl moiety, a chalcone moiety, an azobenzene moiety, or a stilbene moiety is preferred, since photoisomerization is likely to occur and the HTP difference before and after light irradiation is large, and a cinnamoyl moiety, a chalcone moiety, or a stilbene moiety is more preferred, since the absorption of visible light is small.In addition, the photoisomerization moiety corresponds to the photoreactive moiety that undergoes a structural change upon light irradiation as described above.

[0049] Furthermore, the chiral agent A preferably has a trans-type photoisomerizable double bond, in that the initial HTP (before light irradiation) is high and the amount of change in HTP due to light irradiation is excellent. Furthermore, the chiral agent A preferably has a cis-type photoisomerizable double bond, in that the initial HTP (before light irradiation) is low and the amount of change in HTP due to light irradiation is excellent. Furthermore, the chiral agent A is preferably a chiral agent whose HTP changes upon irradiation with light having a wavelength of 350 nm or more, and more preferably a chiral agent whose HTP changes upon irradiation with light having a wavelength of 350 to 370 nm.

[0050] The chiral agent A preferably has any partial structure selected from a binaphthyl partial structure, an isosorbide partial structure (a partial structure derived from isosorbide), and an isomannide partial structure (a partial structure derived from isomannide). The binaphthyl partial structure, the isosorbide partial structure, and the isomannide partial structure each refer to the following structures. The portion in the binaphthyl partial structure where the solid line and the dashed line are parallel represents a single bond or a double bond. In the structures shown below, * represents a bond position.

[0051]

[0052] The chiral agent A is preferably a compound represented by formula (1): Formula (1) P １ -sp １ - (A １ -Z １ ) ｍ -L １-(Z ２ -A ２ ) ｎ -sp ２ -P ２ L １ represents a divalent linking group formed by removing two hydrogen atoms from the structure represented by formula (D) (a divalent linking group formed by removing two hydrogen atoms from the binaphthyl partial structure), a divalent linking group represented by formula (E) (a divalent linking group comprising the isosorbide partial structure), or a divalent linking group represented by formula (F) (a divalent linking group comprising the isomannide partial structure).

[0053] Z １ and Z ２ represents a single bond or a divalent linking group. １ and Z ２ Examples of the divalent linking group represented by the formula: ２ -, -COO-, -CO-S-, -O-CO-O-, -CO-NR-, -SCHR-, -SO-CHR-, -SO ２ -CHR-, -CF ２ O-, -CF ２ S-, -OCHRCHRO-, -SCHRCHRS-, -SO-CHRCHR-SO-, -SO ２ -CHRCHR-SO ２ Preferably, R represents -, -CR=CR-CO-, -CR=CR-COO-, -CR=CR-OCO-, -CR=CR-CONR-, -CR=CR-COS-, -COO-CHRCHR-, -OCO-CHRCHR-, -COO-CHR-, -OCO-CHR-, -CR=CR-, -CR=N-, -N=N-, -CR=N-N=CR-, -CF=CF-, or -C≡C-. R represents a hydrogen atom, a cyano group, or an alkyl group having 1 to 10 carbon atoms. When multiple Rs are present in the formula, the multiple Rs may be the same or different from one another. In the formula, Z １ If there are multiple Z １ may be the same or different. ２ If there are multiple Z ２The Z may be the same or different from each other. １ and multiple Zs ２ It is preferable that at least one of the Z represents a divalent linking group selected from the group consisting of -CR=CR-CO-, -CR=CR-COO-, -CR=CR-OCO-, -CR=CR-CONR-, -CR=CR-COS-, -CR=CR-, -N=N-, and -CF=CF-; １ At least one of, and, and multiple Z ２ It is more preferable that at least one of the groups represented by the formula (I) represents a divalent linking group selected from the group consisting of -CR=CR-CO-, -CR=CR-COO-, -CR=CR-OCO-, -CR=CR-CONR-, -CR=CR-COS-, -CR=CR-, -N=N-, and -CF=CF-.

[0054] A １ and A ２ each independently represents a divalent aromatic ring group which may have a substituent or a divalent alicyclic group which may have a substituent.

[0055] A １ and A ２ Examples of the divalent aromatic ring group represented by the formula (I) include a divalent aromatic hydrocarbon ring group and a divalent aromatic heterocyclic group. The aromatic hydrocarbon ring constituting the divalent aromatic hydrocarbon ring group may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aromatic hydrocarbon ring is preferably 6 to 20, and more preferably 6 to 10. Specific examples of the aromatic hydrocarbon ring are preferably a benzene ring or a naphthalene ring, and more preferably a benzene ring.

[0056] The number of ring members in the aromatic heterocycle constituting the divalent aromatic heterocyclic group is preferably 5 to 10, and more preferably 5 or 6. Examples of heteroatoms contained in the aromatic heterocycle include a nitrogen atom, an oxygen atom, and a sulfur atom. The number of carbon atoms in the aromatic heterocycle is preferably 3 to 20, and more preferably 3 to 10. Specific examples of the aromatic heterocycle include a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, a thiophene ring, a thiazole ring, and an imidazole ring.

[0057] A １ and A ２ The divalent aromatic ring group represented by the formula (I) is preferably a divalent aromatic hydrocarbon ring group, more preferably a divalent benzene ring group or a divalent naphthalene ring group.

[0058] A １ and A ２ Examples of the divalent alicyclic group represented by the formula (I) include a divalent aliphatic hydrocarbon ring group and a divalent aliphatic heterocyclic group. The aliphatic hydrocarbon ring constituting the divalent aliphatic hydrocarbon ring group may be either a monocyclic or polycyclic ring. The number of ring members in the aliphatic hydrocarbon ring is preferably 3 to 20, more preferably 3 to 10, and even more preferably 5 or 6. Specific examples of the aliphatic hydrocarbon ring include a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, a cyclooctane ring, a norbornene ring, and an adamantane ring. Of these, a cyclopentane ring or a cyclohexane ring is preferred.

[0059] The aliphatic heterocycle constituting the divalent aliphatic heterocyclic group may be either a monocycle or a polycycle. Examples of heteroatoms contained in the aliphatic heterocycle include a nitrogen atom, an oxygen atom, and a sulfur atom. The number of ring members in the aliphatic heterocycle is not particularly limited, but is preferably 5 to 10. Specific examples of the aliphatic heterocycle include an oxolane ring, an oxane ring, a piperidine ring, and a piperazine ring. The aliphatic heterocycle may be a ring containing -CH ２ The - may be substituted with -CO-, such as a phthalimide ring.

[0060] A １ and A ２ The substituent that may be possessed by is not particularly limited, and examples thereof include an alkyl group.

[0061] sp １ and sp ２ each independently represents at least one —CH ２ - is -O-, -CO-, -NR Ｘ represents an alkylene group having 1 to 12 carbon atoms which may be substituted with - or -S-. Ｘrepresents a hydrogen atom or an alkyl group (preferably an alkyl group having 1 to 6 carbon atoms). １ and sp ２ At least one -CH ２ - is -O-, -CO-, -NR Ｘ It preferably represents an alkylene group having 1 to 8 carbon atoms which may be substituted with - or -S-, and at least one -CH ２ - is -O-, -CO-, -NR Ｘ More preferably, it represents an alkylene group having 1 to 6 carbon atoms which may be substituted with - or -S-.

[0062] m and n each independently represent an integer of 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, and particularly preferably 2 to 6.

[0063] In formula (1), P １ and P ２ is a hydrogen atom or a monovalent substituent. １ and P ２ Preferably, at least one of the groups represents a polymerizable group, and more preferably, both of the groups represent a polymerizable group. Examples of the polymerizable group include the polymerizable groups described above.

[0064] However, -(A １ -Z １ ) ｍ - and -(Z ２ -A ２ ) ｎ In at least one of the structural moieties represented by -, a cinnamoyl moiety (specifically, -A １ -CR=CR-CO-, or -A ２ -CR=CR-CO-), chalcone moiety (specifically, -A １ -CR=CR-CO-A １ - or -A ２ -CR=CR-CO-A ２ -), an azobenzene moiety (specifically, -A １ -N=N-A １ - or -A ２ -N=N-A ２ -), and a stilbene moiety (specifically, -A１ -CR=CR-A １ - or -A ２ -CR=CR-A ２ The structural moiety containing a cinnamoyl moiety includes at least one moiety selected from the group consisting of -cinnamoyl moiety-O- (specifically, -A １ -CR=CR-CO-O-, or -A ２ -CR=CR-CO-O-) may be used.

[0065] In addition, in the formula (1), when m is an integer of 2 or more, a plurality of Z １ A and multiple A １ When n is an integer of 2 or more, a plurality of Z ２ A and multiple A ２ They may be the same or different from each other.

[0066] In formula (E) and formula (F), * represents a bonding position.

[0067]

[0068] Examples of the chiral agent A include photoreactive chiral agents described in paragraphs 0044 to 0047 of JP-A-2001-159709, optically active compounds described in paragraphs 0019 to 0043 of JP-A-2002-179669, optically active compounds described in paragraphs 0020 to 0044 of JP-A-2002-179633, optically active compounds described in paragraphs 0016 to 0040 of JP-A-2002-179670, optically active compounds described in paragraphs 0017 to 0050 of JP-A-2002-179668, and optically active compounds described in paragraphs 0018 to 0020 of JP-A-2002-180051. optically active compounds described in JP-A-2002-338575, paragraphs 0016 to 0055, optically active isosorbide derivatives described in JP-A-2002-338575, paragraphs 0023 to 0032, photoreactive optically active compounds described in JP-A-2002-080478, paragraphs 0019 to 0029, photoreactive chiral agents described in JP-A-2002-080851, paragraphs 0022 to 0049, optically active compounds described in JP-A-2002-179681, paragraphs 0022 to 0049, optically active compounds described in JP-A-2002-302487, paragraphs 0015 to 0044, and JP-A-2002-338668 optically active polyesters described in paragraphs

[0015] to

[0050] of JP-A-2003-055315; binaphthol derivatives described in paragraphs

[0019] to

[0041] of JP-A-2003-073381; optically active fulgide compounds described in paragraphs

[0008] to

[0043] of JP-A-2003-073381; optically active isosorbide derivatives described in paragraphs

[0015] to

[0057] of JP-A-2003-306490; optically active isosorbide derivatives described in paragraphs

[0015] to

[0041] of JP-A-2003-306491; Examples of optically active isosorbide derivatives include optically active isomannide derivatives described in paragraphs

[0015] to

[0057] of JP-A-2003-313188, optically active isosorbide derivatives described in paragraphs

[0015] to

[0049] of JP-A-2003-313189, optically active polyester / amides described in paragraphs

[0015] to

[0052] of JP-A-2003-313292, optically active compounds described in paragraphs

[0012] to

[0053] of WO2018 / 194157, and optically active compounds described in paragraphs

[0020] to

[0049] of JP-A-2002-179682.

[0069] (Chiral Agent B) The composition of the present invention contains chiral agent B. Chiral agent B is a chiral agent whose HTP does not change upon exposure. Here, the chiral agent whose HTP does not change upon exposure refers to a chiral agent that does not undergo a photoreaction that can cause a change in HTP when irradiated with light having a wavelength of 350 nm or more. Specifically, this refers to a chiral agent that does not have a photoreactive group such as a photoisomerizable group or a photoreactive group that photoreacts when irradiated with light having a wavelength of 350 nm or more. The chiral agent B is not particularly limited as long as it satisfies formula (F1), and may be a chiral agent that induces a helix in the opposite direction to that of chiral agent A, or a chiral agent that induces a helix in the same direction as that of chiral agent A. In particular, chiral agent B is preferably a chiral agent that induces a helix in the opposite direction to that of chiral agent A. In other words, for example, if the helix induced by chiral agent A is left-handed, the helix induced by chiral agent B will be right-handed.

[0070] The chiral agent B preferably has a polymerizable group. The type of the polymerizable group is not particularly limited, but a functional group capable of undergoing an addition polymerization reaction is preferred, a polymerizable ethylenically unsaturated group or a ring-polymerizable group is more preferred, and a (meth)acryloyl group, a vinyl group, a styryl group, or an allyl group is even more preferred. When the chiral agent B has a polymerizable group, the number of polymerizable groups contained per molecule is, for example, preferably 1 to 6, more preferably 2 to 4, and even more preferably 2.

[0071] The chiral agent B may be liquid crystalline or non-liquid crystalline. The chiral agent B generally contains an asymmetric carbon atom. The chiral agent B may be an axially asymmetric compound or a planar asymmetric compound that does not contain an asymmetric carbon atom. As the chiral agent B, a known chiral agent can be used.

[0072] The chiral agent B is preferably a compound represented by formula (2): Formula (2) P ３ -sp ３ - (A ３ -Z ３ ) ｐ -L ２ -(Z ４ -A ４ ) ｑ -sp ４ -P ４In formula (2), L ２ is L in formula (1) １ In formula (2), A has the same meaning as A, and preferred embodiments are also the same. ３ and A ４ is A in formula (1) １ In formula (2), sp ３ and sp ４ is the sp in formula (1). １ In formula (2), P ３ and P ４ is P in formula (1) １ The same definition and preferred embodiments are also the same. ３ and P ４ Preferably, at least one of them represents a polymerizable group, and more preferably, both of them represent a polymerizable group. Examples of the polymerizable group include the polymerizable groups described above. In formula (2), p and q have the same meanings as m in formula (1), and preferred embodiments are also the same.

[0073] In formula (2), Z ３ and Z ４ is Z in formula (1) １ It is synonymous with Z. ３ and Z ４ Examples of the divalent linking group represented by the formula: ２ -, -COO-, -CO-S-, -O-CO-O-, -CO-NR-, -SCHR-, -SO-CHR-, -SO ２ -CHR-, -CF ２ O-, -CF ２ S-, -OCHRCHRO-, -SCHRCHRS-, -SO-CHRCHR-SO-, -SO ２ -CHRCHR-SO ２ -, -COO-CHRCHR-, -OCO-CHRCHR-, -COO-CHR-, or -OCO-CHR- is preferred, and -O-, -CO-, -COO-, or -CO-NR- is more preferred. R represents a hydrogen atom, a cyano group, or an alkyl group having 1 to 10 carbon atoms. When multiple Rs are present in the formula, the multiple Rs may be the same or different from one another. In the formula, Z ３If there are multiple Z ３ may be the same or different. ４ If there are multiple Z ４ They may be the same or different from each other.

[0074] <Physical Properties of Chiral Agents A and B> The molar absorption coefficient of chiral agent A is not particularly limited, but the molar absorption coefficient at the wavelength of light irradiated in step 3 of the production method of the present invention, which will be described later (for example, a wavelength of 365 nm), is preferably 100 to 100,000 L / (mol cm), and more preferably 500 to 50,000 L / (mol cm). As described above, it is also preferable that chiral agent A is a chiral agent whose HTP changes when exposed to light with a wavelength of 350 nm or more (preferably, a wavelength of 350 to 370 nm).

[0075] In the composition of the present invention, the lower limit of the total content of the chiral dopant A and the chiral dopant B is preferably 5.0% by mass or more, more preferably 5.5% by mass or more, and even more preferably 6.0% by mass or more, relative to the total mass of the polymerizable liquid crystal compound in the composition, in terms of ease of controlling the alignment state of the polymerizable liquid crystal compound. The upper limit is preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less, relative to the total mass of the polymerizable liquid crystal compound in the composition.

[0076] The content of the chiral dopant A is preferably 5 to 95% by mass, more preferably 10 to 90% by mass, based on the total content of the chiral dopant A and the chiral dopant B, in terms of ease of controlling the alignment state of the liquid crystal compound.

[0077] The lower limit of the content of the chiral dopant A in the composition of the present invention is preferably 0.1 mass% or more, more preferably 0.5 mass% or more, and even more preferably 1.0 mass% or more, based on the total solid content of the composition. The upper limit is preferably 15 mass% or less, more preferably 12 mass% or less, even more preferably 5.0 mass% or less, and particularly preferably 3.5 mass% or less, based on the total solid content of the composition.

[0078] The lower limit of the content of the chiral dopant B in the composition of the present invention is preferably 1.0 mass% or more, more preferably 2.0 mass% or more, and still more preferably 4.0 mass% or more, based on the total solid content of the composition. The upper limit is preferably 10 mass% or less, more preferably 8.0 mass% or less, and still more preferably 6.0 mass% or less, based on the total solid content of the composition.

[0079] The lower limit of the concentration of the chiral dopant A relative to the polymerizable liquid crystal compound (the content of the chiral dopant A relative to the polymerizable liquid crystal compound (corresponding to a % by mass in formula (F1))) is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and even more preferably 1.0% by mass or more. The upper limit of the concentration of the chiral dopant A relative to the polymerizable liquid crystal compound is preferably 15% by mass or less, more preferably 12% by mass or less, even more preferably 5.0% by mass or less, and particularly preferably 3.5% by mass or less.

[0080] The lower limit of the concentration of the chiral dopant B relative to the polymerizable liquid crystal compound (the content of the chiral dopant B relative to the polymerizable liquid crystal compound (corresponding to b% by mass in formula (F1))) is preferably 1.0% by mass or more, more preferably 2.0% by mass or more, and even more preferably 4.0% by mass or more. The upper limit of the concentration of the chiral dopant B relative to the polymerizable liquid crystal compound (the content of the chiral dopant B relative to the polymerizable liquid crystal compound) is preferably 10% by mass or less, more preferably 8.0% by mass or less, and even more preferably 6.0% by mass or less.

[0081] [Photopolymerization initiator] The composition of the present invention contains a photopolymerization initiator. Examples of the polymerization initiator include known polymerization initiators, and photopolymerization initiators are preferred. Known photopolymerization initiators can be used as the photopolymerization initiator. The content of the photopolymerization initiator in the composition is not particularly limited, but is preferably 0.01 to 20 mass %, and more preferably 0.5 to 10 mass %, based on the total solid content of the composition.

[0082] [Other Components] The composition of the present invention may contain other components in addition to the above-mentioned components. The other components are not particularly limited, and examples thereof include solvents, surfactants, alignment control agents, polymerizable monomers, adhesion improvers, crosslinking agents, polymerization inhibitors, antioxidants, UV absorbers, light stabilizers, colorants, and metal oxide fine particles.

[0083] <Solvent> The composition of the present invention may contain a solvent. The solvent is preferably one that can dissolve each component of the composition, and examples thereof include methyl ethyl ketone, cyclohexanone (anone), and mixed solvents thereof. When the composition contains a solvent, the content of the solvent in the composition is not particularly limited, but is preferably an amount that results in a solids concentration of the composition of 20 to 30 mass%, and more preferably an amount that results in a solids concentration of 20 to 25 mass%.

[0084] <Surfactant> The composition of the present invention may contain a surfactant. Examples of surfactants include conventionally known compounds, such as hydrocarbon surfactants, fluorine-based surfactants, and silicone-based surfactants. From the viewpoint of improving environmental compatibility, it is preferable that the surfactant does not contain a fluorine atom. The surfactant is preferably a hydrocarbon-based surfactant or a silicone-based surfactant. Examples of fluorine-based surfactants include the compounds described in paragraphs

[0028] to

[0056] of JP 2001-330725 A and the compounds described in paragraphs

[0069] to

[0126] of JP 2003-295212 A. The surfactant may be used alone or in combination of two or more types. When the composition contains a surfactant, the content of the surfactant is preferably 0.01 to 5.0% by mass, more preferably 0.01 to 3.0% by mass, and even more preferably 0.05 to 1.0% by mass, based on the total solids content of the composition.

[0085] <Alignment Control Agent> The composition of the present invention may contain an additive (alignment control agent) that promotes horizontal or vertical alignment in order to cause the liquid crystal compound to be horizontally or vertically aligned. Examples of alignment control agents include fluorine (meth)acrylate polymers described in paragraphs

[0018] to

[0043] of JP-A No. 2007-272185, compounds represented by formulas (I) to (IV) described in paragraphs

[0031] to

[0034] of JP-A No. 2012-203237, and compounds described in JP-A No. 2013-113913. Note that one type of alignment control agent may be used alone, or two or more types may be used in combination.

[0086] When the composition contains an alignment control agent, the content of the alignment control agent is preferably 0.01 to 10 mass %, more preferably 0.01 to 5 mass %, and even more preferably 0.02 to 1 mass %, based on the total mass of the polymerizable liquid crystal compound.

[0087] [Embodiment of the Composition of the Present Invention] Hereinafter, one embodiment of the composition of the present invention will be described.

[0088] <Composition of First Embodiment> The composition of the first embodiment is a composition containing the chiral agent A1 and the chiral agent B1 described with reference to FIG. 1 and having a configuration that satisfies formula (F1). The chiral agent A1 is a chiral agent whose HTP decreases upon exposure and induces a left-handed helical direction before and after exposure. The HTP of the chiral agent A1 before exposure is X １ μm －１ The HTP (exposure saturation HTP) obtained by Test 1 is １ μm －１ and X １ >Y １ The chiral agent B1 is a chiral agent B whose HTP does not change upon exposure, and which induces a right-handed helical direction before and after exposure. The HTP of the chiral agent B1 in the composition before and after exposure is expressed as Z １ μm －１ The concentration (amount added) of the chiral agent A1 relative to the polymerizable liquid crystal compound is a １ Mass % and concentration (amount added) of chiral agent B1 relative to polymerizable liquid crystal compound b １ The relationship of mass% is X １ a １ Absolute value of Z １ b １ As shown in the left diagram of FIG. 1, in the cholesteric liquid crystal layer before exposure, the chiral dopant A1 is a left-handed helix, so that X １ a １ On the other hand, since the chiral agent B1 is a right-handed helix, Z １ b １ The value of is negative. The sum of both is X １ a １ +Z １ b １and is a positive value. That is, the helical structure of the cholesteric liquid crystal layer before exposure is a left-handed helical structure. The pitch of the helical structure in the cholesteric liquid crystal layer before exposure is X １ a １ +Z １ b １ Next, when the cholesteric liquid crystal layer is subjected to an exposure treatment, the HTP of the chiral dopant A1 changes to Y １ μm －１ By reducing to Y １ a １ Absolute value of < Z １ b １ and Z, which is the sum of the products of the HTP and the concentration of the chiral agent A and the chiral agent B after exposure, １ b １ +Y １ a １ becomes a negative value. In other words, the helical direction of the helical structure induced by the chiral dopant A1 and the chiral dopant B1 is opposite to the helical structure of the cholesteric liquid crystal layer before exposure. The pitch of the helical structure in the cholesteric liquid crystal layer after exposure is Z １ b １ +Y １ a １ Furthermore, the cholesteric liquid crystal layer is represented by the reciprocal of X １ a １ +Z １ b １ =-(Z １ b １ +Y １ a １ ) and shows the same helical pitch before and after exposure. Expanding the above formula, 1 = -2Z １ b １ / (X １ +Y １ ) a １ In other words, when the helical pitch is the same before and after exposure, the above relational expression is satisfied: 0.90<-2Z １ b １ / (X １ +Y １ ) a １If the ratio is less than 1.10, the deviation in the pitch of the helical structure of the cholesteric liquid crystal layer before and after exposure is small (the selective reflection wavelength of the cholesteric liquid crystal layer before and after exposure is almost the same), and when a cholesteric liquid crystal layer is formed by applying the manufacturing method of the present invention described below, the reflectance is excellent.

[0089] <Composition of Second Embodiment> As shown in Figure 4, the composition of the second embodiment is a composition containing chiral agents A2 and B2 and satisfying formula (F1). Chiral agent A2 is a chiral agent whose HTP decreases upon exposure and induces a right-handed helical spiral before and after exposure. Furthermore, the HTP of chiral agent A2 before exposure is X ２ μm －１ and the HTP obtained by Test 1 is Y ２ μm －１ and X ２ Absolute value of Y ２ The HTP of the chiral agent B2 in the composition before and after exposure is expressed as Z. ２ μm －１ The concentration (amount added) of the chiral agent A2 relative to the polymerizable liquid crystal compound is a ２ Mass % and concentration (amount added) of chiral agent B2 relative to the polymerizable liquid crystal compound ２ The relationship of mass% is X ２ a ２ Absolute value of Z ２ b ２ As shown in the left diagram of FIG. 4, in the cholesteric liquid crystal layer before exposure, the chiral dopant A2 is a right-handed helix, so that X ２ a ２ On the other hand, since the chiral agent B2 is a left-handed helix, Z ２ b ２ The value of is positive. The sum of both is X ２ a ２ +Z ２ b ２and is a negative value. That is, the helical structure of the cholesteric liquid crystal layer before exposure is a right-handed helical structure. The pitch of the helical structure in the cholesteric liquid crystal layer before exposure is X ２ a ２ +Z ２ b ２ Next, when the cholesteric liquid crystal layer is subjected to an exposure treatment, the HTP of the chiral dopant A2 changes to Y ２ μm －１ By reducing to Y ２ a ２ Absolute value of < Z ２ b ２ The relationship between the absolute values ​​of the HTP and the concentration of the chiral agent A2 and the chiral agent B2 after exposure is expressed as Z ２ b ２ +Y ２ a ２ is a positive value. In other words, the helical direction of the helical structure induced by the chiral dopant A2 and the chiral dopant B2 is opposite to the helical structure of the cholesteric liquid crystal layer before exposure. The pitch of the helical structure in the cholesteric liquid crystal layer after exposure is Z ２ b ２ +Y ２ a ２ Furthermore, the cholesteric liquid crystal layer is represented by the reciprocal of -(X ２ a ２ +Z ２ b ２ ) = Z ２ b ２ +Y ２ a ２ The helical pitch is the same before and after exposure. Expanding the above formula, 1 = -2Z ２ b ２ / (X ２ +Y ２ ) a ２ In other words, when the helical pitch is the same before and after exposure, the above relational expression is satisfied: 0.90<-2Z ２ b ２ / (X ２ +Y ２ ) a ２If the ratio is less than 1.10, the deviation in the pitch of the helical structure of the cholesteric liquid crystal layer before and after exposure is small (the selective reflection wavelength of the cholesteric liquid crystal layer before and after exposure is almost the same), and when a cholesteric liquid crystal layer is formed by applying the manufacturing method of the present invention described below, the reflectance is excellent.

[0090] <Composition of Third Embodiment> As shown in Figure 5, the composition of the third embodiment is a composition containing chiral agents A3 and B3 and satisfying formula (F1). Chiral agent A3 is a chiral agent whose HTP decreases upon exposure, and induces a left-handed helix before exposure and a right-handed helix after exposure. Furthermore, the HTP of chiral agent A3 before exposure is X ３ μm －１ and the HTP obtained by Test 1 is Y ３ μm －１ and X ３ Absolute value of Y ３ The HTP of the chiral agent B3 in the composition before and after exposure is expressed as Z. ３ μm －１ The concentration (amount added) of the chiral agent A3 relative to the polymerizable liquid crystal compound is a ３ % by mass, and the concentration (amount added) of the chiral agent B3 relative to the polymerizable liquid crystal compound ３ As shown in the left diagram of FIG. 5, in the cholesteric liquid crystal layer before exposure, the chiral dopant A3 has a left-handed helix, so that X ３ a ３ The value of Z is positive. Also, the chiral agent B3 is a left-handed helix, so Z ３ b ３ The value of is positive. The sum of both is X ３ a ３ +Z ３ b ３ and is a positive value. That is, the helical structure of the cholesteric liquid crystal layer before exposure is a left-handed helical structure. The pitch of the helical structure in the cholesteric liquid crystal layer before exposure is X ３ a ３ +Z ３ b３ Next, when the cholesteric liquid crystal layer is subjected to an exposure treatment, the helical direction of the chiral dopant A3 is reversed to the right, and the HTP is changed to Y ３ μm －１ It decreases to Y ３ a ３ Absolute value of Z ３ b ３ and Z, which is the sum of the products of the HTP and the concentration of the chiral agent A3 and the chiral agent B3 after exposure, ３ b ３ +Y ３ a ３ becomes a negative value. In other words, the helical direction of the helical structure induced by the chiral dopant A3 and the chiral dopant B3 is opposite to the helical structure of the cholesteric liquid crystal layer before exposure. The pitch of the helical structure in the cholesteric liquid crystal layer after exposure is Z ３ b ３ +Y ３ a ３ Furthermore, the cholesteric liquid crystal layer is represented by the reciprocal of X ３ a ３ +Z ３ b ３ =-(Z ３ b ３ +Y ３ a ３ ) and shows the same helical pitch before and after exposure. Expanding the above formula, 1 = -2Z ３ b ３ / (X ３ +Y ３ ) a ３ In other words, when the helical pitch is the same before and after exposure, the above relational expression is satisfied: 0.90<-2Z ３ b ３ / (X ３ +Y ３ ) a ３ If the ratio is less than 1.10, the deviation in the pitch of the helical structure of the cholesteric liquid crystal layer before and after exposure is small (the selective reflection wavelength of the cholesteric liquid crystal layer before and after exposure is almost the same), and when a cholesteric liquid crystal layer is formed by applying the manufacturing method of the present invention described below, the reflectance is excellent.

[0091] <Composition of Fourth Embodiment> As shown in Figure 6, the composition of the fourth embodiment is a composition containing chiral agents A4 and B4 and satisfying formula (F1). Chiral agent A4 is a chiral agent whose HTP increases upon exposure, and induces a left-handed helical twist before and after exposure. Furthermore, the HTP of chiral agent A4 before exposure is X ４ μm －１ and the HTP obtained by Test 1 is Y ４ μm －１ and X ４ Absolute value of Y ４ The HTP of the chiral agent B4 in the composition before and after exposure is expressed as Z. ４ μm －１ The concentration (amount added) of the chiral agent A4 relative to the polymerizable liquid crystal compound is a ４ % by mass, and the concentration (amount added) of the chiral agent B4 relative to the polymerizable liquid crystal compound is b ４ As shown in the left diagram of FIG. 6, in the cholesteric liquid crystal layer before exposure, the chiral dopant A4 is a left-handed helix, so that X ４ a ４ On the other hand, since the chiral agent B4 is a right-handed helix, Z ４ b ４ The value of is negative. The sum of both is X ４ a ４ +Z ４ b ４ and is a negative value. That is, the helical structure of the cholesteric liquid crystal layer before exposure is a right-handed helical structure. Note that the pitch of the helical structure in the cholesteric liquid crystal layer after exposure is X ２ a ２ +Z ２ b ２ Next, when the cholesteric liquid crystal layer is subjected to an exposure treatment, the HTP of the chiral dopant A4 changes to Y ４ μm －１ By increasing to Y ４ a ４ Absolute value of Z ４ b４ and the sum of the products of the HTP and the concentration of the chiral agent A4 and the chiral agent B4 after exposure, Z ４ b ４ +Y ４ a ４ is a positive value. In other words, the helical direction of the helical structure induced by the chiral dopant A4 and the chiral dopant B4 is opposite to the helical structure of the cholesteric liquid crystal layer before exposure. The pitch of the helical structure in the cholesteric liquid crystal layer after exposure is Z ４ b ４ +Y ４ a ４ Furthermore, the cholesteric liquid crystal layer is represented by the reciprocal of -(X ４ a ４ +Z ４ b ４ ) = Z ４ b ４ +Y ４ a ４ The helical pitch is approximately the same before and after exposure. Expanding the above formula, 1 = -2Z ４ b ４ / (X ４ +Y ４ ) a ４ In other words, when the helical pitch is the same before and after exposure, the above relational expression is satisfied: 0.90<-2Z ４ b ４ / (X ４ +Y ４ ) a ４ If the ratio is less than 1.10, the deviation in the pitch of the helical structure of the cholesteric liquid crystal layer before and after exposure is small (the selective reflection wavelength of the cholesteric liquid crystal layer before and after exposure is almost the same), and when a cholesteric liquid crystal layer is formed by applying the manufacturing method of the present invention described below, the reflectance is excellent.

[0092] The value of −2Zb / (X+Y)a in formula (F1) of the composition of the present invention is preferably from 0.94 to 1.06, more preferably from 0.94 to 1.04, and even more preferably from 0.97 to 1.03, in terms of better reflectance.

[0093] [Method for Producing Cholesteric Liquid Crystal Layer of the Present Invention] The method for producing a cholesteric liquid crystal layer of the present invention (the production method of the present invention) is described below. The production method of the present invention comprises the following steps 1 to 5 in this order: Step 1: forming a composition layer of the composition of the present invention on a support; Step 2: aligning the polymerizable liquid crystal compound in the composition layer; Step 3: irradiating the composition layer from the side opposite the support with light of a wavelength capable of changing the HTP of chiral dopant A under conditions of an oxygen concentration of 1% by volume or more; Step 4: heating the composition layer; and Step 5: curing the composition layer to fix the alignment state of the polymerizable liquid crystal compound. The cholesteric liquid crystal layer obtained by the production method of the present invention has a cholesteric liquid crystal phase with a helical direction derived from the cholesteric liquid crystal phase before exposure on the support side, and a cholesteric liquid crystal phase with a helical direction derived from the cholesteric liquid crystal phase after exposure on the side opposite the support. Furthermore, the two cholesteric liquid crystal phases formed in the thickness direction have substantially the same helical pitch. That is, the cholesteric liquid crystal layer has two cholesteric liquid crystal phases along the thickness direction, each of which has approximately the same helical pitch but different helical directions.

[0094] Each step of the production method of the present invention will be described below.

[0095] [Step 1] Step 1 is a step of forming a composition layer of the composition of the present invention on a support. By carrying out this step, a composition layer is formed that is to be subjected to the light irradiation treatment described below. The composition of the present invention is as described above.

[0096] <Support> The support is not particularly limited as long as it can support the composition layer. A transparent support is preferred as the support. The transparent support refers to a support having a visible light transmittance of 60% or more, preferably 80% or more, and more preferably 90% or more.

[0097] The retardation value (Rth(550)) in the thickness direction of the support at a wavelength of 550 nm is not particularly limited, but is preferably −110 to 110 nm, more preferably −80 to 80 nm. The in-plane retardation value (Re(550)) of the support at a wavelength of 550 nm is not particularly limited, but is preferably 0 to 50 nm, more preferably 0 to 30 nm, and even more preferably 0 to 10 nm.

[0098] The material forming the support is preferably a polymer excellent in optical performance transparency, mechanical strength, thermal stability, moisture-shielding property, isotropy, etc. Examples of polymer films that can be used as the support include cellulose acylate films (e.g., cellulose triacetate film (refractive index 1.48), cellulose diacetate film, cellulose acetate butyrate film, cellulose acetate propionate film), polyolefin films such as polyethylene and polypropylene, polyester films such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone films, polyacrylic films such as polymethyl methacrylate, polyurethane films, polycarbonate films, polysulfone films, polyether films, polymethylpentene films, polyether ketone films, (meth)acrylonitrile films, and films of polymers having an alicyclic structure (norbornene-based resins (Arton: trade name, manufactured by JSR Corporation, amorphous polyolefins (Zeonex: trade name, manufactured by Nippon Zeon Co., Ltd.))). Among these, triacetyl cellulose, polyethylene terephthalate, or a polymer having an alicyclic structure is preferred as the material for the polymer film, and triacetyl cellulose is more preferred.

[0099] The support may contain various additives (for example, an optical anisotropy adjusting agent, a wavelength dispersion adjusting agent, fine particles, a plasticizer, an ultraviolet inhibitor, a deterioration inhibitor, a release agent, and the like).

[0100] The thickness of the support is not particularly limited, but is preferably 10 to 200 μm, more preferably 10 to 100 μm, and even more preferably 20 to 90 μm. The support may also be composed of a laminate of multiple sheets. To improve adhesion to a layer disposed thereon, the surface of the support may be subjected to a surface treatment (e.g., glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, flame treatment, etc.). An adhesive layer (undercoat layer) may also be provided on the support. To impart slipperiness during the transport process or to prevent sticking between the back and front surfaces after winding, a polymer layer containing 5 to 40% by mass of inorganic particles with an average particle size of approximately 10 to 100 nm may be disposed on one side of the support.

[0101] The support may be a so-called temporary support, which means that the support may be peeled off from the cholesteric liquid crystal layer after the production method of the present invention is carried out.

[0102] Alternatively, the surface of the support may be directly subjected to rubbing treatment. In other words, a support that has been subjected to rubbing treatment may be used. The direction of the rubbing treatment is not particularly limited, and an optimal direction may be appropriately selected depending on the direction in which the polymerizable liquid crystal compound is desired to be aligned. The rubbing treatment may be a treatment method that is widely used as a liquid crystal alignment treatment step for LCDs (liquid crystal displays). In other words, a method of obtaining alignment by rubbing the surface of the support in a certain direction using paper, gauze, felt, rubber, nylon fiber, polyester fiber, or the like may be used.

[0103] An alignment film may be disposed on the support. The alignment film can be formed by means of rubbing an organic compound (preferably a polymer), oblique deposition of an inorganic compound, formation of a layer having microgrooves, or deposition of an organic compound (e.g., ω-tricosanoic acid, dioctadecylmethylammonium chloride, and methyl stearate) by the Langmuir-Blodgett method (LB film). Furthermore, alignment films that exhibit alignment function upon application of an electric field, a magnetic field, or light irradiation (preferably polarized light) are also known. The alignment film is preferably formed by rubbing a polymer.

[0104] Examples of polymers contained in the alignment film include methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohol and modified polyvinyl alcohol, poly(N-methylolacrylamide), polyesters, polyimides, vinyl acetate copolymers, carboxymethyl cellulose, and polycarbonates, as described in paragraph 0022 of JP-A-8-338913. Silane coupling agents can also be used as the polymer. Among these, water-soluble polymers (e.g., poly(N-methylolacrylamide), carboxymethyl cellulose, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol) are preferred, with gelatin, polyvinyl alcohol, or modified polyvinyl alcohol being more preferred, and polyvinyl alcohol or modified polyvinyl alcohol being even more preferred.

[0105] As described above, the alignment film can be formed by applying a solution containing the above-mentioned polymer, which is an alignment film-forming material, and any additives (e.g., a crosslinking agent) onto a support, followed by heating and drying (crosslinking) and rubbing treatment.

[0106] <Procedure for Step 1> In Step 1, a composition layer containing the above-described components is formed, but the procedure is not particularly limited. Examples include a method in which the composition of the present invention is applied to a support and, if necessary, a drying treatment is performed (hereinafter, also simply referred to as the "coating method"), and a method in which a composition layer is separately formed and transferred to the support. Among these, the coating method is preferred from the viewpoint of productivity. The coating method will be described in detail below. The composition used in the coating method can be the composition of the present invention described above. The coating method is not particularly limited, and examples include wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, and die coating. If necessary, after applying the composition, a drying treatment may be performed on the coating film applied to the support. The drying treatment can remove the solvent from the coating film.

[0107] The thickness of the coating film is not particularly limited, but is preferably 0.1 to 20 μm, more preferably 0.2 to 15 μm, and even more preferably 0.5 to 10 μm.

[0108] [Step 2] Step 2 is a step of aligning the polymerizable liquid crystal compound in the composition layer. By performing this step, the polymerizable liquid crystal compound in the composition layer is aligned in a cholesteric liquid crystal phase. That is, as shown in FIG. 7, step 2 forms a composition layer 12 on a support 10 in which the polymerizable liquid crystal compound LC is aligned in a cholesteric liquid crystal phase. Note that FIG. 7 is a schematic cross-sectional view of the support 10 and the composition layer 12. Step 2 is preferably a step of subjecting the composition layer to a heat treatment (heat aging treatment) to align the polymerizable liquid crystal compound in the composition layer. Optimal conditions for the heat treatment are selected depending on the polymerizable liquid crystal compound used. In particular, the heating temperature is often 25 to 250°C, more often 40 to 150°C, and even more often 50 to 130°C. The heating time is often 0.1 to 60 minutes, more often 0.2 to 5 minutes.

[0109] The alignment state of the polymerizable liquid crystal compound obtained by step 2 varies depending on the HTP and concentration of chiral agent A and chiral agent B. The absolute value of the average HTP of the chiral agent in the composition layer formed by step 2 is 10.0 μm. －１ More than 15.0 μm is preferable. －１ More preferably, 20.0 μm or more －１ The upper limit is not particularly limited, but is preferably 250 μm or more. －１ In most cases, it is less than 200 μm. －１ Preferably less than 100 μm －１ The following is more preferred: When the absolute values ​​of the average HTP of the chiral agent A and the chiral agent B in the composition layer are within the above ranges, the polymerizable liquid crystal compound in the composition can typically be cholesterically aligned by step 2.

[0110] [Step 3] In step 3, after step 2, the composition layer is irradiated with light of a wavelength capable of changing the HTP of the chiral dopant A under conditions of an oxygen concentration of 1% by volume or more. The mechanism of this step is explained below with reference to the drawings. As shown in FIG. 7 , in step 3, light irradiation is performed from the direction opposite the composition layer 12 side of the support 10 (the direction of the white arrow in FIG. 7 ) under conditions of an oxygen concentration of 1% by volume or more. Note that while light irradiation is performed from the support 10 side in FIG. 7 , it may also be performed from the composition layer 12 side. In this case, when comparing the lower region 12A on the support 10 side of the composition layer 12 with the upper region 12B on the opposite side from the support 10 side, the surface of the upper region 12B is closer to the air, so the oxygen concentration in the upper region 12B is higher and the oxygen concentration in the lower region 12A is lower. Therefore, when the composition layer 12 is irradiated with light, polymerization of the polymerizable liquid crystal compound easily proceeds in the lower region 12A, and the orientation state of the polymerizable liquid crystal compound is fixed. Note that the chiral agent A is also present in the lower region 12A, and is also photosensitive, resulting in a change in HTP. However, because the orientation state of the polymerizable liquid crystal compound is fixed in the lower region 12A, even when a heat treatment accompanied by light irradiation in step 3, described below, or a heat treatment in step 5 is performed on the composition layer irradiated with light in step 3, the orientation state of the polymerizable liquid crystal compound does not change. Furthermore, because the oxygen concentration is high in the upper region 12B, even when light is irradiated, the polymerization of the polymerizable liquid crystal compound is inhibited by oxygen, and polymerization does not proceed easily. Furthermore, because the chiral agent A is also present in the upper region 12B, the chiral agent A is photosensitive, resulting in a change in HTP. Therefore, when a heat treatment in step 4 is performed on the composition layer irradiated with light in step 3, described below, the orientation state of the polymerizable liquid crystal compound changes in accordance with the changed HTP. In other words, by performing the light irradiation in step 3, the fixation of the orientation state of the polymerizable liquid crystal compound is likely to proceed in the region (lower region) on the support side of the composition layer. Furthermore, in the region of the composition layer opposite to the support side (upper region), the alignment state of the polymerizable liquid crystal compound is less likely to be fixed, and the HTP of the chiral dopant A is changed by exposure.

[0111] The light irradiation in step 3 is carried out under conditions of an oxygen concentration of 1% by volume or more (for example, in the atmosphere). In particular, the oxygen concentration is preferably 2% by volume or more, more preferably 5% by volume or more, in order to easily form regions in which the orientation state of the polymerizable liquid crystal compound is different in the cholesteric liquid crystal layer. The upper limit is not particularly limited, but may be 100% by volume.

[0112] The light irradiation time in step 3 is preferably 50 seconds or less, more preferably 30 seconds or less, and even more preferably 10 seconds or less. There is no particular lower limit, but from the viewpoint of curing the polymerizable liquid crystal compound, the time is preferably 0.1 seconds or more, and more preferably 0.2 seconds or more. The irradiation dose of light irradiation in step 3 is 300 mJ / cm. ２ Preferably, 250 mJ / cm or less ２ More preferably, 200 mJ / cm or less ２ The lower limit is not particularly limited, but from the viewpoint of curing of the polymerizable liquid crystal compound, it is more preferably 1 mJ / cm ２ More than 5 mJ / cm is preferable. ２ The above is more preferable. The light irradiation in step 3 is preferably carried out at a temperature of 15 to 70°C (preferably 25 to 50°C).

[0113] The light used for photoirradiation may be any light to which the chiral agent A is photosensitive. In other words, the light used for photoirradiation is not particularly limited as long as it is actinic ray or radiation that changes the HTP of the chiral agent A, and examples thereof include the bright line spectrum of a mercury lamp, far ultraviolet light represented by an excimer laser, extreme ultraviolet light, X-rays, ultraviolet light, and electron beams. Of these, ultraviolet light is preferred. Furthermore, the light used for photoirradiation is preferably light with a wavelength of 350 nm or more (preferably, a wavelength of 350 to 370 nm). When performing ultraviolet irradiation, it is also preferable to use an LED lamp having an emission peak wavelength of 365 nm.

[0114] Heat treatment may be carried out during the light irradiation in step 3. The heat treatment accompanying the light irradiation in step 3 is the same as in step 4 below, and will be described in step 4 below.

[0115] [Step 4] Step 4 is a step of subjecting the composition layer to a heat treatment. Step 4 is preferably a step of subjecting the composition layer to a heat treatment at a temperature higher than that at which the composition layer is irradiated with light in Step 3, since this facilitates the formation of a predetermined cholesteric liquid crystal layer. By performing Step 4, the orientation state of the polymerizable liquid crystal compound changes in the region in the composition layer subjected to the light irradiation in Step 3, where the HTP of the chiral agent A has changed. More specifically, Step 4 is a step of subjecting the composition layer after the light irradiation in Step 3 to a heat treatment (preferably at a temperature higher than that at which the composition layer is irradiated with light in Step 3) to align the polymerizable liquid crystal compound in the composition layer that has not been fixed by the light irradiation in Step 3. The mechanism of this step is explained below with reference to the drawings.

[0116] As described above, when the composition layer 12 shown in FIG. 7 is irradiated with light in step 3, the orientation state of the polymerizable liquid crystal compound is fixed in the lower region 12A, whereas the polymerization of the polymerizable liquid crystal compound is difficult to proceed in the upper region 12B, and the orientation state of the polymerizable liquid crystal compound is not fixed. Furthermore, in the upper region 12B, the average HTP of chiral agent A and chiral agent B changes due to a change in the HTP of chiral agent A. When such a change in the HTP of chiral agent A occurs, the force twisting the polymerizable liquid crystal compound in the upper region 12B changes compared to the state before light irradiation in step 3. The change in the twisting force of chiral agent A and chiral agent B in the cholesteric liquid crystal phase subjected to light exposure is as described in the composition of the present invention. The change in the HTP of chiral agent A due to light exposure causes the helical direction of the cholesteric liquid crystal phase in the upper region 12B to be opposite to the helical direction of the cholesteric liquid crystal phase in the lower region 12A. That is, when the helical direction of the cholesteric liquid crystal phase in the lower region 12A is leftward, the helical direction of the cholesteric liquid crystal phase in the upper region 12B is rightward.

[0117] When the upper region 12B is exposed (irradiated with light) by light irradiation in step 3, and the HTP of chiral agent A is reduced by exposure as shown in FIG. 1 , the right-handed HTP derived from chiral agent B becomes relatively stronger in the upper region 12B in FIG. 7 . Therefore, when the composition layer 12 after light irradiation in step 3, in which such a change in average HTP has occurred, is subjected to a heat treatment in step 4 to promote reorientation of the polymerizable liquid crystal compound, in the upper region 12B, the twist direction of the polymerizable liquid crystal compound LC is oriented in the opposite direction to that in the lower region 12A along the helical axis extending along the thickness direction of the composition layer 12. On the other hand, as described above, in the lower region 12A of the composition layer 12, polymerization of the polymerizable liquid crystal compound has progressed during light irradiation in step 3, and the orientation state of the polymerizable liquid crystal compound has been fixed, so reorientation of the polymerizable liquid crystal compound does not proceed. As described above, by performing step 4, cholesteric liquid crystal layers having cholesteric liquid crystal phases with approximately the same helical pitch but different helical directions are formed along the thickness direction of the composition layer.

[0118] In the upper part, an example is shown in which a composition containing chiral agent A1 and chiral agent B1 shown in Figure 1 (composition of the first embodiment) is applied to the manufacturing method of the present invention, but even when a composition of another embodiment is used, by performing step 4, a cholesteric liquid crystal layer is formed along the thickness direction of the composition layer, having cholesteric liquid crystal phases with approximately the same helical pitch but different helical directions.

[0119] The heat treatment in step 4 is preferably carried out at a temperature higher than that during light irradiation in step 3. The difference between the temperature during the heat treatment in step 4 and the temperature during light irradiation in step 3 is preferably 5°C or more, more preferably 10 to 110°C, and even more preferably 20 to 110°C.

[0120] The temperature of the heat treatment in step 4 is preferably higher than the temperature during light irradiation in step 3 and is a temperature at which the unfixed polymerizable liquid crystal compound in the composition layer is aligned, and more specifically, is often 40 to 250° C., more often 50 to 150° C., even more often higher than 50° C. and not higher than 150° C., and particularly often 60 to 130° C. The heating time in step 4 is often 0.01 to 60 minutes, more often 0.03 to 5 minutes.

[0121] Alternatively, instead of step 4, a heat treatment may be carried out when the light irradiation is carried out in step 3. When the heat treatment is carried out when the light irradiation is carried out in step 3, the heat treatment may be carried out before the light irradiation or during the light irradiation. When the heat treatment is carried out when the light irradiation is carried out in step 3, the heating temperature and heating time are as described above.

[0122] [Step 5] Step 5 is a step of fixing the alignment state of the polymerizable liquid crystal compound by subjecting the composition layer to a curing treatment after the heat treatment in Step 4 (i.e., after realigning the polymerizable liquid crystal compound). By undergoing Step 5, a cholesteric liquid crystal layer can be formed in which cholesteric liquid crystal phases having substantially the same helical pitch but different helical directions are fixed along the thickness direction of the composition layer.

[0123] The curing method is not particularly limited, and examples thereof include photocuring and heat curing. Of these, photoirradiation is preferred, and ultraviolet irradiation is more preferred. For ultraviolet irradiation, a light source such as an ultraviolet lamp is used. A wavelength cut filter may also be used during ultraviolet irradiation. The irradiation dose of light (e.g., ultraviolet) is not particularly limited, but is generally 100 to 800 mJ / cm. ２ The atmosphere during light irradiation is not particularly limited, and light irradiation may be carried out in air or in an inert atmosphere. In particular, light irradiation is preferably carried out in an oxygen concentration of less than 1% by volume.

[0124] When a photocuring treatment is carried out as the curing treatment in step 5, the temperature conditions during photocuring are not particularly limited as long as the temperature maintains the alignment state of the polymerizable liquid crystal compound after the heat treatment in step 4. The difference between the temperature in the heat treatment in step 4 and the temperature in the photocuring treatment in step 5 is preferably within 100° C., more preferably within 80° C. It is preferable that the temperature in the heat treatment in step 4 and the temperature in the photocuring treatment in step 4 are the same, or that the temperature in the photocuring treatment in step 5 is lower.

[0125] In the cholesteric liquid crystal layer obtained by carrying out the curing treatment, the orientation state of the polymerizable liquid crystal compound is fixed. In this specification, the "fixed" state refers to a state in which the orientation of the polymerizable liquid crystal compound is maintained, which is the most typical and preferred embodiment. While not limited thereto, specifically, it is more preferable that the layer has no fluidity and can stably maintain the fixed orientation state without causing any change in the orientation state due to an external field or external force, usually within a temperature range of 0 to 50°C, or under more severe conditions, within a temperature range of -30 to 70°C. In the cholesteric liquid crystal layer, it is not necessary for the composition in the layer to finally exhibit liquid crystallinity.

[0126] The thickness of the cholesteric liquid crystal layer is not particularly limited, but is preferably 0.05 to 10 μm, more preferably 0.1 to 8.0 μm, and even more preferably 0.2 to 6.0 μm. The thickness of the cholesteric liquid crystal is particularly preferably 1.8 μm or less, and most preferably 1.3 μm or less.

[0127] The cholesteric liquid crystal layer formed by the above method and having a fixed cholesteric liquid crystal phase has two cholesteric liquid crystal phases along the thickness direction, each having approximately the same helical pitch but opposite helical directions. That is, the cholesteric liquid crystal layer formed by the above method and having a fixed cholesteric liquid crystal phase has, along the thickness direction, a region (hereinafter also referred to as the "first region") in which a cholesteric liquid crystal phase exhibiting one of a rightward and leftward helical direction is fixed, and a region (hereinafter also referred to as the "second region") in which a cholesteric liquid crystal phase having a helical direction opposite to that of the first region is fixed. The selective reflection center wavelengths derived from the cholesteric liquid crystal phase in each region are approximately the same. Furthermore, each cholesteric liquid crystal phase in the first region and the second region typically has a helical axis approximately parallel to the thickness direction. For example, the cholesteric liquid crystal layer may be a cholesteric liquid crystal layer having, along the thickness direction, a first region in which a cholesteric liquid crystal phase that reflects right-handed blue light is fixed and a second region in which a cholesteric liquid crystal phase that reflects left-handed blue light is fixed, or a cholesteric liquid crystal layer having, along the thickness direction, a first region in which a cholesteric liquid crystal phase that reflects right-handed green light is fixed and a second region in which a cholesteric liquid crystal phase that reflects left-handed green light is fixed, or a cholesteric liquid crystal layer having, along the thickness direction, a first region in which a cholesteric liquid crystal phase that reflects right-handed red light is fixed and a second region in which a cholesteric liquid crystal phase that reflects left-handed red light. min (%), the half-value transmittance is expressed by the following formula: T １／２ The half-value transmittance is the average value of two wavelengths (%). １／２ =100-(100-T min ) ÷ 2 Furthermore, among visible light, light in the wavelength range of 420 nm or more and less than 500 nm is blue light (B light), light in the wavelength range of 500 nm or more and less than 600 nm is green light (G light), and light in the wavelength range of 600 nm or more and less than 700 nm is red light (R light).

[0128] [Cholesteric Liquid Crystal Layer] The cholesteric liquid crystal layer of the present invention is a cholesteric liquid crystal layer formed from the composition of the present invention. The cholesteric liquid crystal layer of the present invention is a cholesteric liquid crystal layer formed by fixing a cholesteric liquid crystal phase, and preferably has a structure having two cholesteric liquid crystal phases along the thickness direction, each having substantially the same helical pitch but opposite helical directions. That is, the cholesteric liquid crystal layer of the present invention preferably has a structure having, along the thickness direction, a region (first region) in which a cholesteric liquid crystal phase exhibiting one of a rightward and leftward helical direction is fixed, and a region (second region) in which a cholesteric liquid crystal phase having a helical direction opposite to that of the first region is fixed. The selective reflection center wavelengths derived from the cholesteric liquid crystal phase in each region are substantially the same. Furthermore, each cholesteric liquid crystal phase in the first region and the second region typically has a helical axis substantially parallel to the thickness direction.

[0129] The thickness of the cholesteric liquid crystal layer is not particularly limited, but is preferably 0.05 to 10 μm, more preferably 0.1 to 8.0 μm, and even more preferably 0.2 to 6.0 μm. The thickness of the cholesteric liquid crystal is particularly preferably 1.8 μm or less, and most preferably 1.3 μm or less.

[0130] [Reflective Film] The cholesteric liquid crystal layer can be used as a reflective film. Furthermore, the reflective film formed from the cholesteric liquid crystal layer can be suitably used as a combiner for a head-up display (e.g., an in-vehicle head-up display system) by being incorporated into a windshield glass.

[0131] The present invention will be described in more detail below with reference to examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the examples shown below.

[0132] Example 1 Preparation of Liquid Crystal Composition a The following components were mixed to prepare liquid crystal composition a. Composition of Liquid Crystal Composition a 100.0 parts by mass of polymerizable liquid crystal compound LC1 shown below 3.0 parts by mass of photopolymerization initiator (OXE01, manufactured by BASF) 1.2 parts by mass of compound C (adhesion improver) shown below 0.1 parts by mass of compound D (alignment control agent) shown below 10.8 parts by mass of compound X1 (corresponding to chiral agent A) shown below 2.6 parts by mass of compound Y1 (corresponding to chiral agent B) Mixed solvent (methyl ethyl ketone (MEK) / anone (mass ratio 70 / 30)) Amount to give a solids concentration of 20% by mass

[0133] -Polymerizable liquid crystal compound LC1-

[0134] The polymerizable liquid crystal compound LC1 has a refractive index anisotropy Δn of 0.15 at a wavelength of 550 nm.

[0135] -Compound C-

[0136] -Compound D-

[0137] -Compound X1-

[0138] -Compound Y1-

[0139] [Measurement of HTP of Chiral Agent A] <Pre-exposure HTP of Compound X1 and Exposure-Saturated HTP of Compound X1> Hereinafter, the procedure for measuring the pre-exposure HTP and exposure-saturated HTP of Compound X1, which corresponds to chiral agent A, will be described.

[0140] (Preparation of Evaluation Composition) A composition for evaluation having the following composition was prepared. ------------------ Evaluation composition ---------------------------------- Compound X1: 5 parts by mass Polymerizable liquid crystal compound LC-1: 100 parts by mass Mixed solvent (MEK (methyl ethyl ketone) / cyclohexanone=90 / 10 (mass ratio)): amount such that the solids concentration of the composition becomes 30% by mass.

[0141] (Preparation of a support with an alignment film) A polyimide alignment film material SE-130 (manufactured by Nissan Chemical Industries, Ltd.) was applied to a cleaned glass support to form a coating film. The resulting coating film was baked and then subjected to a rubbing treatment to prepare a support with an alignment film.

[0142] (HTP Measurement) <<Measurement of HTP before exposure of Compound X1>> 40 μL of the composition for evaluation was spin-coated on the rubbed surface of the support with the alignment film at 1500 rpm for 10 seconds, and the resulting coating film was then heat-treated (dried and aged) at 90° C. for 1 minute to form a composition layer. The central reflection wavelength of the resulting composition layer was measured at room temperature (23° C.), and the HTP (initial HTP (HTP before exposure)) was calculated according to the following formula (F5). Formula (F5): HTP=(average refractive index of liquid crystal compound) / {(concentration (mass %) of chiral agent relative to liquid crystal compound)×(central reflection wavelength)}[μm －１ ]

[0143] <<Measurement of Exposure Saturation HTP of Compound X1>> Next, an LED lamp (manufactured by Acroedge Co., Ltd., "ULW365-21701-5F") having an emission peak wavelength of 365 nm was used to expose the composition layer at an exposure dose of 10 mJ / cm. ２ to 10 mJ / cm ２The composition layer was exposed to light at 15 or more different positions while increasing the exposure time, and the HTP at each exposed position was determined. More specifically, the central reflection wavelength was measured at each exposed position, and the HTP at each exposed position was calculated in the same manner as in formula (F5). Next, the HTP at each exposed position was plotted on an orthogonal coordinate system with HTP on the vertical axis and exposure amount on the horizontal axis, and points corresponding to the HTP and exposure amount at each exposed position were plotted from the obtained HTP-exposure amount correlation curve. ２ The HTP (exposure saturation HTP) at which the rate of change in HTP before and after the increase was within 1% was identified. This exposure saturation HTP corresponds to the "HTP at the exposure dose at which there is no change in HTP (i.e., Y in formula (F1))" for compound X1. The rate of change in HTP can be calculated using the following formula (F6). Formula (F6): Rate of change in HTP = | {(HTP before increase in exposure dose) - (exposure dose increased to 10 mJ / cm ２ (HTP after increasing exposure dose) / (HTP before increasing exposure dose)×100|[%]

[0144] As a result of the above measurement, the HTP before exposure of compound X1 (corresponding to the X value in formula (F1)) was 30 μm －１ and the exposure saturation HTP (corresponding to the Y value in formula (F1)) is 0 μm. －１ It was confirmed that the compound X1 induces a left-handed helix.

[0145] [Measurement of HTP of Chiral Agent B] <HTP of Compound Y1> The HTP of Compound Y1 corresponding to chiral agent B was determined in the same manner as the measurement method for the pre-exposure HTP of Compound X1 corresponding to Chiral Agent A described above, except that Compound X1 was changed to Compound Y1. As a result of the above measurement, the HTP of Compound Y1 before exposure (corresponding to the Z value in Formula (F1)) was -60 μm －１ It was confirmed that compound Y1 induces a right-handed helix. Compound Y1 is a chiral agent that does not undergo a photoreaction that can cause a change in HTP even when exposed to light with a wavelength of 350 nm or more, and the HTP after exposure treatment to change the HTP of chiral agent A was the same as the HTP before exposure.

[0146] [Preparation of Reflective Film] Liquid crystal composition a was applied to a TAC (triacetyl cellulose) film on which an alignment film had been formed so that the film thickness after drying would be 1.3 μm. After application, the film was left to stand at room temperature for 15 seconds, and then subjected to heat treatment (drying and aging) in a 60°C atmosphere for 30 seconds. Thereafter, ultraviolet light (wavelength 365 nm) was irradiated at 60 mJ / cm from the side opposite the TAC film in an atmosphere at 40°C. ２ After that, the film was irradiated with 300 mJ / cm 2 of a metal halide lamp, which cuts off wavelengths of 330 nm or less, in a 50°C environment with an oxygen concentration of 100 ppm by volume or less. ２ By fixing the cholesteric liquid crystal phase by exposing the TAC film to an integrated light amount of 1000 kJ / cm, a cholesteric liquid crystal layer was formed on the TAC film, in which two cholesteric phases having substantially the same helical pitch but different helical directions were fixed, in that order from the TAC film side, to form a cholesteric liquid crystal layer having a two-layer structure in which a reflective layer (first layer) that reflects left-handed circularly polarized light and a reflective layer (second layer) that reflects right-handed circularly polarized light were laminated together. In other words, a two-layer structure reflective layer having a first layer, which is a reflective layer for left-handed circularly polarized light, on the lower layer side and a second layer, which is a reflective layer for right-handed circularly polarized light, on the upper layer side was formed together.

[0147] Example 2 Preparation of Liquid Crystal Composition d Liquid crystal composition d was prepared by mixing the components shown below. ---------------- Composition of Liquid Crystal Composition d ---------------- 100.0 parts by mass of the above polymerizable liquid crystal compound LC1; 3.0 parts by mass of photopolymerization initiator (OXE01, manufactured by BASF); 1.2 parts by mass of the above compound C (adhesion improver); 0.1 parts by mass of the above compound D (alignment control agent); 12.9 parts by mass of the following compound X2 (corresponding to chiral agent A); 1.7 parts by mass of the above compound Y1 (corresponding to chiral agent B); Mixed solvent (methyl ethyl ketone (MEK) / anone (mass ratio 70 / 30)) in an amount to give a solids concentration of 20% by mass.

[0148] -Compound X2-

[0149] [Measurement of HTP of Chiral Agent A] <Pre-exposure HTP of Compound X2 and Exposure Saturation HTP of Compound X2> The pre-exposure HTP and exposure saturation HTP of Compound X2 were measured by the above-mentioned procedure. The pre-exposure HTP of Compound X2 (corresponding to the X value in formula (F1)) was 21 μm －１ and the exposure saturation HTP (corresponding to the Y value in formula (F1)) is −6.5 μm. －１ It was confirmed that the compound X2 induces a left-handed helix before exposure and a right-handed helix after exposure.

[0150] [Preparation of Reflective Film] A reflective film of Example 2 was prepared by the same procedure as in Example 1, except that liquid crystal composition a was replaced with liquid crystal composition d. Specifically, a cholesteric liquid crystal layer was formed on a TAC film, in order from the TAC film side, by fixing two cholesteric phases having approximately the same helical pitch but different helical directions, thereby forming a two-layer reflective layer in which a reflective layer (first layer) that reflects left-handed circularly polarized light and a reflective layer (second layer) that reflects right-handed circularly polarized light were laminated. In other words, a two-layer reflective layer was formed in one step, with the first layer (left-handed circularly polarized reflective layer) on the lower layer side and the second layer (right-handed circularly polarized reflective layer) on the upper layer side.

[0151] Comparative Example 1 (two liquid crystal layers with different alignment layers) A reflective film was produced in the same manner as in Example 1, except that the liquid crystal composition a was changed to the composition (3) for forming an optically anisotropic layer described in Example 3 of WO 2021 / 033631.

[0152] Comparative Example 2 (Layer Formation by Lamination) Preparation of Liquid Crystal Composition b The components shown below were mixed to prepare a liquid crystal composition b.

[0153] ------------------------------------------------ Composition of liquid crystal composition b---------------------------------------------------------------- Polymerizable liquid crystal compound LC1 100.0 parts by mass Photopolymerization initiator (OXE01, manufactured by BASF) 3.0 parts by mass Compound C (adhesion improver) 1.2 parts by mass Compound D (alignment control agent) 0.1 parts by mass Compound X1 (corresponding to chiral agent A) 5.8 parts by mass Mixed solvent (methyl ethyl ketone (MEK) / anone (mass ratio 70 / 30)) Amount to give a solids concentration of 20% by mass------------------------------------------------

[0154] [Preparation of Liquid Crystal Composition c] The components shown below were mixed to prepare a liquid crystal composition c.

[0155] ------------------------------------------------ Composition of liquid crystal composition c---------------------------------------------------------------- Polymerizable liquid crystal compound LC1 100.0 parts by mass Photopolymerization initiator (OXE01, manufactured by BASF) 3.0 parts by mass Compound C (adhesion improver) 1.2 parts by mass Compound D (alignment control agent) 0.1 parts by mass Compound Y1 (corresponding to chiral agent B) 3.0 parts by mass Mixed solvent (methyl ethyl ketone (MEK) / anone (mass ratio 70 / 30)) Amount to give a solids concentration of 20% by mass------------------------------------------------

[0156] [Preparation of Reflective Film] Liquid crystal composition b was applied onto a TAC film having an alignment layer formed thereon so that the film thickness after drying would be 0.65 μm. After application, the film was left to stand at room temperature for 15 seconds, and then heated in a 60°C atmosphere for 30 seconds. Thereafter, the film was irradiated with 300 mJ / cm of light from a metal halide lamp that cuts off wavelengths of 330 nm or less in a 50°C environment with an oxygen concentration of 100 ppm by volume or less. ２The TAC film was exposed to light with an integrated light intensity of 1000 kJ / cm 2 , thereby fixing the cholesteric liquid crystal phase, and a first layer (a reflective layer for left-handed circularly polarized light) was formed on the TAC film. Then, a second layer (a reflective layer for right-handed circularly polarized light) was formed on the TAC film using the same procedure as above, using liquid crystal composition c. The TAC film with the first layer and the TAC film with the second layer obtained above were then bonded together so that the TAC film sides were in close contact. Specifically, an adhesive (SK-2057, manufactured by Soken Chemical & Engineering Co., Ltd.) was applied to the TAC film side of the first layer (reflective layer for left-handed circularly polarized light) to form an adhesive layer, and the TAC film of the second layer (reflective layer for right-handed circularly polarized light) was bonded together so that it was in close contact.

[0157] [Various Evaluations] [Measurement of Reflectance of Reflective Film] Using a spectrophotometer (V-670, manufactured by JASCO Corporation), P-polarized light was incident on the obtained reflective film from a direction at an angle of 5° to the normal direction of the film, and the reflectance at 850-950 nm was measured, and evaluation was performed based on the following evaluation criteria. The results are shown in Table 1. (Evaluation criteria) A: Reflectance 95% or more B: Reflectance 75% or more but less than 95% C: Reflectance 55% or more but less than 75% D: Reflectance less than 55%

[0158] [Measurement of Thickness Unevenness of Reflective Film] The largest possible square on the surface of the second layer side of the reflective film is divided equally into eight vertical and horizontal sections to form 64 sub-regions. The reflective film is cut parallel to the rubbing direction through the center of the sub-region, and the thickness d1 of the first layer (lower layer) and the thickness d2 of the second layer (upper layer) are measured from the exposed cross section. The ratio Z of the thickness d1 to the total layer thickness (d1 + d2) (= the maximum value Z of d1 / (d1 + d2)) is calculated. ｍａｘ and the minimum value Z ｍｉｎ The ratio (Z ｍａｘ / Z ｍｉｎ The obtained values ​​were classified and evaluated based on the following evaluation criteria. The results are shown in Table 1.

[0159] (Evaluation criteria) A: 1 or more and less than 1.05 B: 1.05 or more and less than 1.1 C: 1.1 or more and less than 1.15 D: 1.15 or more

[0160] Table 1 is shown below. In the table, the definitions of X, Y, Z, a, and b in "-2Zb / (X+Y)a" are the same as the definitions of X, Y, Z, a, and b in formula (F1). In the "Production method" column in the table, the case where a two-layer cholesteric liquid crystal layer (reflective layer) was formed by simultaneous coating of the composition is shown as "composition," and the case where it was formed by lamination is shown as "lamination."

[0161]

[0162] It was confirmed that the reflective layer (cholesteric liquid crystal layer) of the example had excellent reflectance and little unevenness in film thickness.

[0163] 2 Support 4 Composition layer EX １ , EX ２ , EX ３ Exposure HTP １ , H.T.P. ２ , H.T.P. ３ Helical induction force ΔT HTP ２ and HTP ３ 10: Substrate; LC: Polymerizable liquid crystal compound; 12: Composition layer; 12B: Upper region; 12A: Lower region

Claims

1. A composition comprising a polymerizable liquid crystal compound, a chiral agent A whose helical twisting power changes upon exposure, a chiral agent B whose helical twisting power does not change upon exposure, and a photopolymerization initiator, and satisfying the following formula (F1): Formula (F1): 0.90 < -2Zb / (X+Y)a < 1.10 In the formula, X is the helical twisting power of the chiral agent A before exposure. Y is the helical twisting power of the chiral agent A obtained by the following test 1. Z is the helical twisting power of the chiral agent B. a is the concentration of the chiral agent A relative to the polymerizable liquid crystal compound. b is the concentration of the chiral agent B relative to the polymerizable liquid crystal compound. However, X, Y, and Z in formula (F1) are negative values ​​when a right-handed helix is ​​induced, and positive values ​​when a left-handed helix is ​​induced. The unit of the helical twisting power is μm －１ The unit of the concentration is % by mass. Test 1: The chiral agent A is exposed to light using a light-emitting diode having an emission peak wavelength of 365 nm, the helical twisting power of the chiral agent A is measured for each exposure dose, and the helical twisting power at the exposure dose at which the change in the helical twisting power no longer exists is defined as Y.

2. The composition according to claim 1, wherein the chiral agent A is a compound represented by the following formula (1): Formula (1) P １ -sp １ - (A １ -Z １ ) ｍ -L １ -(Z ２ -A ２ ) ｎ -sp ２ -P ２ In the ceremony, L １ represents a divalent linking group formed by removing two hydrogen atoms from a structure represented by the following formula (D), a divalent linking group represented by the following formula (E), or a divalent linking group represented by the following formula (F). In formulas (E) and (F), * represents a bonding position. Z １ and Z ２ each independently represents a single bond or a divalent linking group. １ and A ２ each independently represents a divalent aromatic ring group which may have a substituent or a divalent alicyclic group which may have a substituent. １ and sp ２ each independently represents at least one —CH ２ - is -O-, -CO-, -NR Ｘ represents an alkylene group having 1 to 12 carbon atoms which may be substituted with - or -S-. Ｘ represents a hydrogen atom or an alkyl group. １ and P ２ are each independently a hydrogen atom or a monovalent substituent, and m and n are each independently an integer of 1 to 10. However, in the formula, -(A １ -Z １ ) ｍ - and -(Z ２ -A ２ ) ｎ At least one of the structural moieties represented by - includes a moiety selected from the group consisting of a cinnamoyl moiety, a chalcone moiety, an azobenzene moiety, and a stilbene moiety.

3. The composition according to claim 1 or 2, wherein the helical twisting power of the chiral agent A changes when irradiated with light having a wavelength of 350 nm or more.

4. The composition according to claim 1 or 2, wherein the Δn of the polymerizable liquid crystal compound is 0.15 or more.

5. A method for producing a cholesteric liquid crystal layer, comprising the steps of: step 1 forming a composition layer of the composition described in claim 1 on a support; step 2 orienting the polymerizable liquid crystal compound in the composition layer; step 3 irradiating the composition layer from the side opposite the support with light of a wavelength that can change the helical twisting power of the chiral agent A under conditions of an oxygen concentration of 1% by volume or more; step 4 heating the composition layer; and step 5 curing the composition layer to fix the orientation state of the polymerizable liquid crystal compound.

6. A cholesteric liquid crystal layer formed using the composition of claim 1.

7. A reflective film having the cholesteric liquid crystal layer according to claim 6.

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