Composition, method for manufacturing cholesteric liquid crystal layer, cholesteric liquid crystal layer, reflective film

Abstract

A first object of the present application is to provide a composition capable of forming a cholesteric liquid crystal layer having excellent reflectivity and less film thickness unevenness, and having a region with a cholesteric liquid crystal phase having a right-handed helical direction and a region with a cholesteric liquid crystal phase having a left-handed helical direction along the thickness direction. Also, a second object of the present application is to provide 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 above composition. The composition of the present application contains a polymerizable liquid crystal compound, a chiral agent A whose helical twisting power changes due to exposure, a chiral agent B whose helical twisting power does not change due to exposure, and a photopolymerization initiator, and satisfies the following formula (F1). Formula (F1): 0.90 < -2Zb / (X+Y)a < 1.10

Description

Technical Field

[0001] This invention relates to a composition, a method for manufacturing a cholesteric liquid crystal layer, a cholesteric liquid crystal layer, and a reflective film. Background Technology

[0002] Recently, as one of the in-vehicle displays, a so-called head-up display system has been developed that projects various information as images onto the windshield and other surfaces using a projector and conveys it to the driver.

[0003] As a head-up display system, for example, there are known head-up display systems in which a reflective film comprising a cholesteric liquid crystal layer exhibiting selective reflection of circularly polarized light is assembled in a windshield. Furthermore, the cholesteric liquid crystal layer is configured to have a reflective spectrum with a wide reflective band spanning the visible region, and therefore it is often constructed by stacking multiple cholesteric liquid crystal layers with different central reflective wavelengths (in other words, originating from different pitches of the liquid crystal compounds).

[0004] For example, Patent Document 1 discloses an optical film comprising a light-reflecting layer R composed of a cholesteric liquid crystal layer having a right-handed helical orientation, a light-reflecting layer L composed of a cholesteric liquid crystal layer having a left-handed helical orientation, and a polarizing element layer. In Patent Document 1, the light-reflecting layer R and the light-reflecting layer L are manufactured by bonding them together with an adhesive.

[0005] Previous technical documents

[0006] Patent documents

[0007] Patent Document 1: International Publication No. 2016 / 002582 Summary of the Invention

[0008] The technical problem to be solved by the invention

[0009] Referring to the optical film described in Patent Document 1, the inventors attempted to form a reflective layer by bonding a cholesteric liquid crystal layer having a right-handed helical direction and a cholesteric liquid crystal layer having a left-handed helical direction. As a result, they found that uneven film thickness was easily generated, and it was clear that this needed to be improved.

[0010] Furthermore, the reflective layer itself requires high reflectivity as a basic performance characteristic.

[0011] Therefore, the objective of this invention is to provide a composition capable of forming a cholesteric liquid crystal layer with excellent reflectivity and minimal thickness non-uniformity. More specifically, the objective of this invention is to provide a composition capable of forming a cholesteric liquid crystal layer with excellent reflectivity and minimal thickness non-uniformity, having regions having a cholesteric liquid crystal phase with a right-handed helical orientation and regions having a cholesteric liquid crystal phase with a left-handed helical orientation along the thickness direction.

[0012] Furthermore, the objective of this invention is to provide a cholesteric liquid crystal layer, a method for manufacturing the cholesteric liquid crystal layer, and a reflective film related to the above composition.

[0013] means for solving technical problems

[0014] The inventors have discovered that the above-mentioned problems can be solved by the following configuration.

[0015] [1] A composition comprising a polymerizable liquid crystal compound, a chiral agent A whose helical torsion force changes with exposure, a chiral agent B whose helical torsion force does not change with exposure, and a photopolymerization initiator, and satisfying formula (F1) described below.

[0016] [2] The composition according to [1], wherein, The chiral agent A mentioned above is the compound represented by formula (1) described later.

[0017] [3] The composition according to [1] or [2], wherein, The helical twisting force of the chiral agent A described above will change when it is irradiated with light with a wavelength of 350 nm or higher.

[0018] [4] The composition according to any one of [1] to [3], wherein, The Δn of the aforementioned polymeric liquid crystal compound is 0.15 or higher.

[0019] [5] A method for manufacturing a cholesteric liquid crystal layer, comprising, in sequence: Step 1: Forming a composition layer of any one of [1] to [4] on a support; Step 2, oriented the polymeric liquid crystal compound in the above composition layer; Step 3: Under conditions where the oxygen concentration is 1% by volume or higher, light of a wavelength that can change the helical torsion force of the chiral agent A is irradiated from the side of the above-mentioned composition layer opposite to the above-mentioned support. Step 4: Heating the above-mentioned composition layer; and Step 5 involves curing the above-mentioned composition layer to fix the orientation state of the polymeric liquid crystal compound.

[0020] [6] A cholesteric liquid crystal layer formed using any one of [1] to [4].

[0021] [7] A reflective film having the cholesteric liquid crystal layer described in [6].

[0022] Invention Effects

[0023] According to the present invention, a composition is provided that can form a cholesteric liquid crystal layer having excellent reflectivity and minimal thickness non-uniformity, and having regions having cholesteric liquid crystal phases with a right-handed helical orientation and regions having cholesteric liquid crystal phases with a left-handed helical orientation along the thickness direction.

[0024] Furthermore, according to the present invention, a cholesteric liquid crystal layer, a method for manufacturing the cholesteric liquid crystal layer, and a reflective film related to the above composition can be provided. Attached Figure Description

[0025] Figure 1 This is a schematic diagram illustrating an example of the mechanism of action and implementation method of the composition of the present invention.

[0026] Figure 2 This is a schematic diagram used to illustrate the exposure treatment of Experiment 1.

[0027] Figure 3 This is a schematic diagram used to illustrate the exposure treatment of Experiment 1.

[0028] Figure 4 This is a schematic diagram illustrating an example of an embodiment of the composition of the present invention.

[0029] Figure 5 This is a schematic diagram illustrating an example of an embodiment of the composition of the present invention.

[0030] Figure 6 This is a schematic diagram illustrating an example of an embodiment of the composition of the present invention.

[0031] Figure 7 This is a schematic diagram illustrating the manufacturing method of the present invention. Detailed Implementation

[0032] The present invention will now be described in detail.

[0033] The following description of the constituent elements is sometimes based on representative embodiments of the present invention, but the present invention is not limited to such embodiments.

[0034] In addition, in this specification, the numerical range indicated by “~” refers to the range included by taking the values ​​recorded before and after “~” as the lower limit and upper limit values.

[0035] Furthermore, in this specification, "(meth)acrylate" refers to both acrylic acid and methacrylate, "(meth)acryloyl" refers to both acryloyl and methacryloyl, and "(meth)acrylic acid" refers to both acrylic acid and methacrylic acid.

[0036] Furthermore, in the description of groups (atomic groups) in this specification, the descriptions of unsubstituted and unsubstituted groups include groups without substituents, as well as groups with substituents. For example, "alkyl" includes not only unsubstituted alkyl groups (unsubstituted alkyl groups), but also substituted alkyl groups (substituted alkyl groups).

[0037] Unless otherwise specified, the bonding direction of the divalent groups (e.g., -CO-O-) described in this specification is not limited. For example, if Y in the compound represented by the formula "XYZ" is -CO-O-, the compound can be "XO-CO-Z" or "X-CO-OZ".

[0038] Unless otherwise specified, the "light" used in the exposure process described in this specification refers to active light or radiation, such as the bright-line spectrum of a mercury lamp, far-ultraviolet light represented by an excimer laser, extreme ultraviolet (EUV) light, X-rays, ultraviolet light, and electron beams (EB). Among these, ultraviolet light is preferred.

[0039] In addition, unless otherwise specified, "light irradiation" and "exposure" have the same meaning in this instruction manual.

[0040] Unless otherwise specified, "light" in the descriptions of parts other than exposure processing in this instruction manual refers to visible light and natural light (unpolarized light).

[0041] In this specification, "visible light" refers to light in the wavelength range of 380–780 nm. Furthermore, unless otherwise specified, the wavelength for measurement in this specification is 550 nm.

[0042] In addition, in visible light, light in the wavelength region of 420–490 nm is blue (B) light, light in the wavelength region of 495–570 nm is green (G) light, and light in the wavelength region of 620–750 nm is red (R) light.

[0043] In this specification, "non-visible light" refers to light with wavelengths less than 380 nm or greater than 780 nm.

[0044] In this specification, the cholesteric liquid crystal phase is a phase having a periodic structure with a helical orientation of the liquid crystal compound and a twist angle of 360° or more. Furthermore, when the liquid crystal compound is twisted and oriented in optically anisotropic layers other than the cholesteric liquid crystal phase, the twist angle is preferably greater than 0° and less than 360°.

[0045] In this specification, "increase and decrease of helical torsion force" refers to the increase or decrease when the initial helical direction of the chiral agent (before light irradiation (exposure)) is set to "positive". Therefore, when the helical torsion force continuously decreases due to light irradiation and exceeds 0, and the helical direction becomes "negative" (i.e., when a helical direction opposite to the initial helical direction is induced), it also corresponds to "chiral agent with decreased helical torsion force".

[0046] Furthermore, regarding the helical direction, the right-handed and left-handed directions are determined based on the surface of the cholesteric liquid crystal layer (a composite layer in which the liquid crystal compound is oriented in a cholesteric liquid crystal phase) opposite to the surface of the observation side.

[0047] In this specification, unless otherwise specified, terms related to angles such as "angle expressed in specific numerical values," "parallel," "horizontal," "vertical," and "orthogonal" are included within the generally permissible error range in this technical field. Specifically, this refers to a range of ±10° or less from the strict angle. The error from the strict angle is preferably ±7° or less, more preferably ±5° or less.

[0048] In this specification, the terms “same” and “entire surface” are included within the range of tolerances generally permissible in this art, unless otherwise specified.

[0049] In this specification, "visible light transmittance" is defined as the visible light transmittance of light source A as specified in JIS (Japanese Industrial Standard) R 3212:2015 (Test Method for Safety Glass for Automobiles). That is, the transmittance is calculated as follows: using light source A, the transmittance of each wavelength in the wavelength range of 380–780 nm is measured by a spectrophotometer. The transmittance at each wavelength is then multiplied by a weighting factor obtained according to the wavelength distribution and wavelength interval of the CIE (International Commission on Illumination) light adaptability standard, and the result is averaged.

[0050] When simply referred to as "reflected light" or "transmitted light," it is used to encompass both scattered and diffracted light.

[0051] 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 set to 550 nm. Furthermore, the in-plane retardation is measured by incident light of wavelengths within the visible light range onto the normal direction of the thin film.

[0052] Furthermore, in this specification, "solid components" of the composition refer to the components that form the cholesteric liquid crystal layer formed using the composition. In the case where the composition contains a solvent (organic solvent, water, etc.), it refers to all components after the solvent has been removed. Moreover, any liquid component that forms the cholesteric liquid crystal layer is also considered a solid component.

[0053] [Composition]

[0054] The composition of the present invention

[0055] It includes polymerizable liquid crystal compounds, chiral agent A whose helical torsion force changes upon exposure (hereinafter also referred to as "HTP"), chiral agent B whose helical torsion force does not change upon exposure, and photopolymerization initiators. And it satisfies the following equation (F1).

[0056] Equation (F1): 0.90 < -2Zb / (X+Y)a < 1.10 In the formula, X is the helical torsion force of the chiral agent A before exposure.

[0057] Y is the helical torsion force of the chiral agent A obtained through the following test 1.

[0058] Z represents the helical torsion force of the chiral agent B mentioned above.

[0059] 'a' represents the concentration of the chiral agent A relative to the polymeric liquid crystal compound.

[0060] b represents the concentration of the chiral agent B relative to the polymerizable liquid crystal compound.

[0061] In equation (F1), X, Y, and Z become negative values ​​when a right-handed spiral is induced, and positive values ​​when a left-handed spiral is induced.

[0062] In addition, the unit of the aforementioned helical torsional force is μm. -1 The concentrations mentioned above are in units of mass.

[0063] Experiment 1: The chiral agent A was exposed using a light-emitting diode with a peak emission wavelength of 365 nm. The helical torsion force of the chiral agent A at each exposure was measured. The helical torsion force at the exposure where the helical torsion force no longer changed was set as Y.

[0064] According to the composition of the present invention, when applied to the method for manufacturing a cholesteric liquid crystal layer described later (hereinafter also referred to as "the manufacturing method of the present invention"), a cholesteric liquid crystal layer having regions having a cholesteric phase with a right-handed helical direction and regions having a cholesteric phase with a left-handed helical direction along the thickness direction can be formed. Compared with the case where cholesteric liquid crystal layers with a right-handed helical direction and cholesteric liquid crystal layers with a left-handed helical direction are bonded together, the cholesteric liquid crystal layer thus formed has less film thickness inhomogeneity.

[0065] Furthermore, in the cholesteric liquid crystal layer formed by the composition of the present invention, as described later, the pitch of the cholesteric phase having the above-described right-handed helical direction and the cholesteric phase having the above-described left-handed helical direction are approximately the same (the selective reflection wavelength of the cholesteric liquid crystal layer before and after exposure is approximately the same), thus the reflectivity is also excellent.

[0066] The proposed mechanism of action of the compositions of the present invention will be described below. Furthermore, after describing the proposed mechanism of action of the compositions of the present invention, the characteristic features of the manufacturing method of the present invention will also be described.

[0067] [Mechanism of Action of the Compositions of the Invention]

[0068] First, we will explain the HTP (helical torsion force) of the hand agent.

[0069] The HTP of a chiral agent refers to the factor that exhibits the helical orientation ability expressed by the following formula (F2).

[0070] Formula (F2) HTP = 1 / (pitch length (unit: μm) × chiral agent concentration relative to liquid crystal compound (mass%)) [μm -1 ]

[0071] The pitch length refers to the length of the spacing P (=the period of the helix) of the helical structure of the cholesteric liquid crystal phase, which can be measured using the method described on page 196 of the Liquid Crystal Handbook (Maruzen Publishing Co., Ltd.). That is, when it is desired to adjust the pitch P of the cholesteric liquid crystal phase to a certain length, the concentration (amount) of the chiral agent with a large HTP decreases, and conversely, when using a chiral agent with a small HTP, the concentration (amount) increases.

[0072] Furthermore, the HTP of chiral agents can also be expressed as the following formula (F3).

[0073] Equation (F3): HTP = (Average refractive index of liquid crystal compound) / {(Concentration of chiral agent relative to liquid crystal compound (mass%)) × (Central reflection wavelength (nm))} [μm -1 ]

[0074] Furthermore, when the composition contains two or more chiral agents, the pitch P of the cholesteric liquid crystal phase is determined by the sum of the products of the HTP calculated for each chiral agent contained in the composition and its concentration (amount added).

[0075] HTP induced by two or more chiral agents (hereinafter, also 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 (mass%) of each chiral agent contained in the composition relative to the liquid crystal compound by the total concentration (mass%) of the chiral agents relative to the liquid crystal compound. For example, when two chiral agents are used simultaneously (e.g., chiral agent X and chiral agent Y), it is represented by the following formula (F4).

[0076] Equation (F4) Average HTP (μm) -1 ) = (HTP of chiral agent X (μm) -1 ) × Concentration (mass%) of chiral agent X relative to liquid crystal compound + HTP (μm) of chiral agent Y -1 () × Concentration of chiral agent Y relative to liquid crystal compound (mass%) / (Concentration of chiral agent X relative to liquid crystal compound (mass%) + Concentration of chiral agent Y relative to liquid crystal compound (mass%))

[0077] In equations (F1) to (F4) above, when the chiral agent has a right-handed helix, its HTP is set to a negative value. Conversely, when the chiral agent has a left-handed helix, its HTP is set to a positive value. That is, for example, HTP is 10 μm. -1 In the case of chiral agents, when the helical direction of the helix induced by the aforementioned chiral agent is left-handed, HTP is represented as 10 μm. -1 On the other hand, when the helical direction of the helix induced by the aforementioned chiral agent is right-handed, HTP is expressed as -10 μm. -1 .

[0078] The composition of the present invention comprises a chiral agent A whose HTP changes upon exposure and a chiral agent B whose HTP does not change upon exposure, and the HTP and concentration of chiral agent A and chiral agent B satisfy formula (F1).

[0079] Regarding the helical structure of the cholesteric liquid crystal layer obtained by heating and curing the composition layer formed by the composition of the present invention, when the cholesteric liquid crystal layer is exposed (by exposure, the HTP of chiral agent A changes), the pitch remains approximately unchanged, but the helical direction becomes the opposite direction to the helical structure of the cholesteric liquid crystal layer before exposure.

[0080] The above-mentioned mechanism of action will be explained below by taking as an example a cholesteric liquid crystal layer formed by the composition of the present invention containing chiral agent A1 and chiral agent B1 having predetermined properties.

[0081] Figure 1 This is a schematic diagram illustrating the change in the helical structure of the cholesteric liquid crystal layer formed from the above composition before and after exposure. The change in the helical structure can be adjusted according to the HTP and concentration of chiral agents A1 and B1.

[0082] Chiral agent A1 is a chiral agent A whose HTP decreases due to exposure, and it is a chiral agent that induces a left-handed helical direction before and after exposure. Furthermore, the HTP of chiral agent A1 before exposure is 1 μm. -1 The HTP (hereinafter also referred to as "exposure saturation HTP") obtained by Experiment 1 described later is Y1μm. -1 The relationship is X1 > Y1. Chiral agent B1 is a chiral agent B whose HTP does not change due to exposure, and it is a chiral agent that induces a right-handed helical direction before and after exposure. The HTP of chiral agent B1 in the composition before and after exposure is Z1 μm. -1 Furthermore, the relationship between the concentration (addition amount) a1 of chiral agent A1 relative to the polymerizable liquid crystal compound and the concentration (addition amount) b1 of chiral agent B1 relative to the polymerizable liquid crystal compound was adjusted so that the absolute value of X1a1 > the absolute value of Z1b1.

[0083] like Figure 1 As shown in the left figure, in the cholesteric liquid crystal layer before exposure, chiral agent A1 is a left-handed helix, therefore the value of X1a1 is positive. On the other hand, chiral agent B1 is a right-handed helix, therefore the value of Z1b1 is negative. Furthermore, the sum of the two is X1a1 + Z1b1, which is positive. That is, the helical structure of the cholesteric liquid crystal layer before exposure becomes a left-handed helix. In addition, the pitch of the helical structure in the cholesteric liquid crystal layer before exposure is represented by the reciprocal of X1a1 + Z1b1. Next, if the cholesteric liquid crystal layer is subjected to exposure treatment, the HTP of chiral agent A1 decreases to Y1μm. -1This results in a relationship where the absolute value of Y1a1 < the absolute value of Z1b1. After exposure, the sum of the products of HTP and concentration of chiral agents A and B, i.e., Z1b1 + Y1a1, becomes negative. That is, the helical direction of the helical structure induced by chiral agents A1 and B1 becomes the opposite direction to the helical structure of the cholesteric liquid crystal layer before exposure. Furthermore, the pitch of the helical structure in the cholesteric liquid crystal layer after exposure is expressed as the reciprocal of Z1b1 + Y1a1. Moreover, the aforementioned cholesteric liquid crystal layer becomes X1a1 + Z1b1 = -(Z1b1 + Y1a1), exhibiting the same pitch before and after exposure. Expanding the above equation, it is expressed as 1 = -2Z1b1 / (X1 + Y1)a1. That is, when exhibiting the same pitch before and after exposure, the above relationship is satisfied. Through the inventors' research, it was found that if 0.90 < -2Z1b1 / (X1+Y1)a1 < 1.10, the pitch deviation 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 the reflectivity is excellent when the cholesteric liquid crystal layer is formed by the manufacturing method of the present invention described later.

[0084] [Characteristics of the manufacturing method of the present invention]

[0085] The composition of the present invention described above is preferably used in the manufacturing method of the present invention.

[0086] As will be described in detail later, in the manufacturing method of the present invention, firstly, a composition layer formed of the composition of the present invention is formed on a support (step 1), and the polymerizable liquid crystal compound in the composition layer is oriented to form a cholesteric liquid crystal phase (step 2). In step 3, the oxygen concentration is low in a certain region on the support side of the composition layer, and high in other regions on the surface side opposite to the support side. Therefore, in such a composition layer, if light capable of changing the wavelength of the HTP of chiral agent A is irradiated, although a change in the HTP of chiral agent A occurs in the region with high oxygen concentration (e.g., photoisomerization or photodimerization), the polymerization of the polymerizable components (polymerizable liquid crystal compound, and, in the case where chiral agent A and chiral agent B are polymerizable chiral agents, corresponding to this) is difficult to carry out due to oxygen hindrance. In contrast, the polymerization reaction of the aforementioned polymerizable components is easier to carry out in the region with low oxygen concentration. Furthermore, in regions with low oxygen concentrations, although changes in the HTP of chiral agent A occur (e.g., photoisomerization or photodimerization), the polymerization reaction proceeds more rapidly. As a result, the orientation state of the polymerizable liquid crystal compound is fixed by polymerization before changes in the orientation state of the polymerizable liquid crystal compound caused by the changes in the HTP of chiral agent A occur.

[0087] Then, through the reorientation process in step 4 and the curing process in step 5, the orientation state of the liquid crystal compound is reoriented in the region of step 3 where the oxygen concentration is high and the polymerization reaction is difficult to carry out, and is immobilized by polymerization. As a result, a cholesteric liquid crystal layer is formed, consisting of two cholesteric liquid crystal phases with approximately the same pitch and different helical directions along the thickness direction of the composition layer.

[0088] That is, when the composition of the present invention, which includes chiral agent A1 and chiral agent B1 having predetermined properties, as shown as an example in the upper section, is applied to the manufacturing method of the present invention, a cholesteric liquid crystal layer is formed having a cholesteric liquid crystal phase with a helical direction originating from the cholesteric liquid crystal layer before exposure on the support side and a cholesteric liquid crystal phase with a helical direction originating from the cholesteric liquid crystal layer after exposure on the side opposite to the support. Furthermore, the pitch of the two cholesteric liquid crystal phases formed along the thickness direction is approximately the same.

[0089] [Specific steps of Experiment 1]

[0090] Hereinafter, an example of the specific steps for measuring the post-exposure HTP (exposure-saturated HTP, where Y in formula (F1) corresponds to this) of the chiral agent A in the composition of the present invention will be described.

[0091] First, an evaluation composition is prepared by mixing the chiral agent A and the polymeric liquid crystal compound contained in the composition of the present invention with a solvent capable of dissolving the chiral agent A and the polymeric liquid crystal compound. Next, the obtained evaluation composition is coated onto a support and dried to form a composition layer. Additionally, an alignment film (e.g., a rubbing alignment film) may be formed on the support.

[0092] Next, an LED with a peak emission wavelength of 365 nm was used to increase the exposure intensity while simultaneously exposing the composite layer. Specifically, the exposure intensity was increased from 10 mJ / cm². 2 Every 10mJ / cm 2 Simultaneously, more than 15 exposures are performed at different locations on the composition layer. That is, more than 15 different locations on the surface of the composition layer are exposed to different amounts of light. More specifically, such as... Figure 2 As shown by the hollow arrows, exposure levels are varied at different locations within the composition layer. Additionally, in Figure 2 In this process, the composition layer 4 disposed on the support 2 is exposed at three different locations. Figure 2 In the leftmost exposure, the exposure amount is measured in EmJ / cm. 2 The exposure is below, and the exposure in the center is set to an exposure amount of (E+10) mJ / cm. 2The exposure below, in the rightmost exposure, is set to an exposure amount of (E+10×2) mJ / cm. 2 The exposure is then adjusted. Thus, for each exposure portion, the exposure is increased by 10 mJ / cm². 2 At the same time, it will be exposed.

[0093] In addition, the area of ​​the exposed portion is not particularly limited; for example, it can be approximately 10mm in length and 20mm in width.

[0094] Furthermore, as an exposure section, more than 15 exposure points can be performed. There is no particular limit to the number of exposure sections, but it is preferable to perform the exposure until the HTP temporarily reaches a minimum after exposure of the chiral agent (described later). Figure 3 The chiral agent shown exhibits a minimum value, but depending on the type of chiral agent, it may sometimes exhibit a maximum value. ) and is generally constant, more preferably below 30.

[0095] Next, the exposed composition layer is heated at 90°C for 1 minute to orient the polymerizable liquid crystal compound, thereby forming a cholesteric liquid crystal phase. The heating mechanism is not particularly limited; for example, an oven can be used.

[0096] Next, the center reflection wavelength is measured in each exposed section, and the HTP of each exposed section is calculated according to the above formula (F3).

[0097] Next, a scatter plot was created using the HTP and exposure data for each exposure segment. Specifically, points corresponding to the HTP and exposure amount for each exposure segment were plotted on an orthogonal coordinate system with HTP as the vertical axis and exposure amount as the horizontal axis. That is, a graph (HTP-exposure correlation curve) was created by setting the HTP of each exposure segment to the vertical axis and the exposure amount of each exposure segment to the horizontal axis. Furthermore, the unit of the vertical axis is μm. -1 The unit of exposure is mJ / cm. 2 .exist Figure 3 An example of a scatter plot is shown below. Additionally, Figure 3 The black circles in the diagram correspond to the results (HTP and exposure) for each exposure portion. Figure 3 For ease of explanation, the number of black circles is less than the actual 15 points. Furthermore, lines can be created by connecting the plotted points in the obtained scatter plot.

[0098] like Figure 3As shown, for example, chiral agent A, which can change HTP through reactions such as photoisomerization or photodimerization, exhibits a significant change in HTP during the initial exposure phase. However, once a certain constant exposure level is reached, the chiral agent reaches reaction equilibrium, and HTP hardly changes. Here, "disappearance of HTP change" means that the rate of change of HTP at two adjacent plotted points becomes less than 1%. Specifically, if in the context of... Figure 3 Adjacent plotted E in X2 E X3 The relationship between the HTPs (HTP2 and HTP3) corresponding to the exposure amount is explained in terms of the change rate represented by |{(HTP2-HTP3) / HTP2}×100|[%] being less than 1%.

[0099] Therefore, for example, in Figure 3 When the rate of change from HTP1 to HTP2 exceeds 1%, and the rate of change from HTP2 to HTP3 is less than 1%, E X2 This corresponds to the exposure level at which the HTP change disappears in Experiment 1.

[0100] As a light-emitting diode with a peak emission wavelength of 365nm, it is possible to use an LED lamp with a peak emission wavelength of 365nm ("ULW365-21701-5F" manufactured by AcroEdge Co., Ltd.) that is sold by AcroEdge Co., Ltd.

[0101] The components that may be included in the compositions of the present invention are described below.

[0102] [Polymerizable liquid crystal compounds]

[0103] The compositions of the present invention comprise polymerizable liquid crystal compounds. Polymerizable liquid crystal compounds are liquid crystal compounds having polymerizable groups.

[0104] The polymerizable liquid crystal compound can be either a rod-shaped liquid crystal compound or a disc-shaped liquid crystal compound, but a rod-shaped liquid crystal compound is preferred.

[0105] Rod-shaped nematic liquid crystal compounds can be listed as examples. Among these, methyleneamines, azo compounds, cyanobiphenyl compounds, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexane compounds, cyano-substituted phenylpyrimidine compounds, alkoxy-substituted phenylpyrimidine compounds, phenyl dioxane compounds, diphenylacetylene compounds, or alkenylcyclohexylbenzylnitrile compounds are preferred.

[0106] It can use not only low-molecular-weight liquid crystal compounds, but also high-molecular-weight liquid crystal compounds.

[0107] Polymerizable liquid crystal compounds can be obtained by introducing polymeric groups into a liquid crystal compound.

[0108] The types of polymerizable groups in a polymerizable liquid crystal compound are not particularly limited. Functional groups capable of addition polymerization are preferred, and polymerizable olefinically unsaturated groups or cyclopolymerizable groups are more preferred. Examples of such groups include unsaturated polymerizable groups (e.g., (meth)acryloyl, vinyl, styryl, and allyl), epoxy, and aziridinyl groups. Unsaturated polymerizable groups are preferred, and olefinically unsaturated polymerizable groups are more preferred. Polymerizable groups can be introduced into the molecule of the liquid crystal compound by various methods.

[0109] The polymeric liquid crystal compound preferably has 1 to 6 polymeric groups in one molecule, more preferably 1 to 3.

[0110] Examples of polymerizable liquid crystal compounds include those described in Makromol. Chem., Vol. 190, pp. 2255 (1989), Advanced Materials, Vol. 5, pp. 107 (1993), U.S. Patent No. 4,683,327, U.S. Patent No. 5,622,648, U.S. Patent No. 5,770,107, International Publication Nos. 95 / 022586, 95 / 024455, 97 / 00600, 98 / 23580, 98 / 52905, Japanese Patent Application Publication Nos. 1-272551, 6-016616, 7-110469, 11-080081, and 2001-328973.

[0111] Two or more polymerizable liquid crystal compounds can be used simultaneously in the composition.

[0112] The lower limit of Δn for the polymerizable liquid crystal compound is preferably 0.15 or more. As for the upper limit of Δn, from the viewpoint that the composition readily satisfies formula (F1), it is preferably less than 0.55, more preferably less than 0.50, even more preferably less than 0.30, and particularly preferably less than 0.20. As for the Δn of the polymerizable liquid crystal compound, it is more preferably 0.15 to 0.30, and even more preferably 0.15 to 0.20. The above Δn represents the refractive index anisotropy at a wavelength of 550 nm.

[0113] The content of the polymerizable liquid crystal compound in the composition of the present invention is not particularly limited, but from the viewpoint of easily controlling the orientation state of the liquid crystal compound, it is preferably 60% by mass or more, more preferably 70% by mass or more, relative to the total solid content of the composition. The upper limit is not particularly limited, but it is preferably 99% by mass or less, more preferably 97% by mass or less, further preferably 95% by mass or less, and particularly preferably 90% by mass or less.

[0114] [Chiral agent A]

[0115] The composition of the present invention contains a chiral agent (chiral agent A) that changes upon exposure to HTP.

[0116] Chiral agent A preferably has polymerizable groups.

[0117] The types of polymerizable groups are not particularly limited, but functional groups capable of addition polymerization are preferred, polymerizable olefinic unsaturated groups or cyclic polymerizable groups are more preferred, and (meth)acryloyl, vinyl, styrene or allyl are even more preferred.

[0118] When the chiral agent A has polymerizable groups, the number of polymerizable groups contained in each molecule is preferably 1 to 6, more preferably 2 to 4, and even more preferably 2.

[0119] Chiral agent A can be either liquid crystal or non-liquid crystal. Chiral agent A typically contains asymmetric carbon atoms. Alternatively, chiral agent A can also be an axial chiral compound or a planar chiral compound that does not contain asymmetric carbon atoms.

[0120] Chiral agent A can be a chiral agent whose HTP increases due to light irradiation (exposure), or a chiral agent whose HTP decreases due to light irradiation (exposure). Preferably, it is a chiral agent whose HTP decreases due to light irradiation.

[0121] As chiral agents A, examples include so-called photoreactive chiral agents, etc.

[0122] Photoreactive chiral agents have chiral sites and photoreactive sites whose structure changes due to light irradiation. For example, they are compounds that cause a significant change in the torsional force of liquid crystal compounds depending on the amount of irradiation.

[0123] Examples of photoreactive sites whose structure changes due to light irradiation include photochromic compounds (Kingo Uchida & Masahiro Irie, Chemical Industry, vol. 64, 640p, 1999; Kingo Uchida & Masahiro Irie, Fine Chemical, vol. 28(9), 15p, 1999). Furthermore, these structural changes refer to decomposition, addition reactions, isomerization, racemization, [2+2] photocyclization, and dimerization reactions that occur when light is irradiated onto the photoreactive site; these structural changes can be irreversible. Moreover, chiral sites, such as the asymmetric carbon described in Hiroyuki Nohira, General Chemical Studies, No. 22 Liquid Crystal Chemistry, 73p: 1994, correspond to this.

[0124] As chiral agent A, a compound having at least a photoisomerization site is preferred, and the photoisomerization site is more preferably a double bond capable of photoisomerization. As the aforementioned photoisomerization site having a photoisomerization-capable double bond, from the viewpoint of easily generating photoisomerization and having a large difference in HTP before and after light irradiation, a cinnamyl site, a chalcone site, an azobenzene site, or a stilbene site is preferred; from the viewpoint of lower visible light absorption, a cinnamyl site, a chalcone site, or a stilbene site is more preferred. Furthermore, the photoisomerization site corresponds to the aforementioned photoreaction site whose structure changes upon light irradiation.

[0125] Furthermore, from the viewpoint that the HTP is high in the initial stage (before light irradiation) and the amount of HTP change caused by light irradiation is superior, chiral agent A preferably has a trans-type double bond that can be photoisomerized.

[0126] Furthermore, from the viewpoint that the initial HTP is low (before light irradiation) and the amount of HTP change caused by light irradiation is superior, chiral agent A preferably has a cis-type double bond that is photoisomerizable.

[0127] Furthermore, chiral agent A is preferably a chiral agent in which HTP changes upon irradiation by light with a wavelength of 350 nm or higher, and more preferably a chiral agent in which HTP changes upon irradiation by light with a wavelength of 350 to 370 nm.

[0128] Chiral agent A preferably has a structure selected from the binatidine moiety, the isosorbide moiety (a moiety derived from isosorbide), and the isomannitol moiety (a moiety derived from isomannitol). Furthermore, the binatidine moiety, the isosorbide moiety, and the isomannitol moiety each refer to the following structures.

[0129] In the binaphthalene moiety structure, the parallel solid and dashed lines represent single or double bonds. Additionally, in the structures shown below, Indicates the bonding location.

[0130] [Chemical Formula 1]

[0131] As chiral agent A, the compound represented by formula (1) is preferred.

[0132] Equation (1) P 1 -sp 1 -(A 1 -Z 1 ) m -L 1 -(Z 2 -A 2 ) n -sp 2 -P 2

[0133] L 1 The term refers to a divalent linker formed by removing two hydrogen atoms from the structure represented by formula (D) (a divalent linker formed by removing two hydrogen atoms from the above-mentioned naphthalene part of the structure), a divalent linker represented by formula (E) (a divalent linker composed of the above-mentioned isosorbide part of the structure), or a divalent linker represented by formula (F) (a divalent linker composed of the above-mentioned isomannitol part of the structure).

[0134] Z 1 and Z 2 This indicates a single bond or a divalent linker.

[0135] As Z 1 and Z 2 The divalent linking group represented is preferably -O-, -S-, -CHRCHR-, -OCHR-, -CO-, -SO-, -SO2-, -COO-, -CO-S-, -O-CO-O-, -CO-NR-, -SCHR-, -SO-CHR-, -SO2-CHR-, -CF2O-, -CF2S-, -OCHRCHRO-, -SCHRCHRS-, -SO-CHRCHR-SO-, -SO 2-CHRCHR-SO2-, -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=NN=CR-, -CF=CF-, or -C≡C-. R represents a hydrogen atom, a cyano group, or an alkyl group having 1 to 10 carbon atoms. Furthermore, when multiple Rs are present in the formula, the Rs can be the same or different from each other.

[0136] There are multiple Z in the formula. 1In the case of multiple Z 1 They can be the same or different. Furthermore, there are multiple Z's in the formula. 2 In the case of multiple Z 2 They can be the same or different.

[0137] Furthermore, it is preferable that there are multiple Z. 1 and the existence of multiple Z 2 At least one of the Z groups represents a divalent linker 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-, more preferably, multiple Z groups are present. 1 At least one and multiple Z in 2 At least one of them represents a divalent linker 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-.

[0138] A 1 and A 2 Each can be independently represented as a divalent aromatic cyclic group that may have substituents or a divalent alicyclic group that may have substituents.

[0139] As A 1 and A 2 The divalent aromatic cyclic group can be represented by divalent aromatic hydrocarbon cyclic groups and divalent aromatic heterocyclic groups.

[0140] The aromatic hydrocarbon ring constituting the divalent aromatic hydrocarbon ring group can be either a monocyclic or polycyclic aromatic ring. Furthermore, the number of carbon atoms in the aromatic hydrocarbon ring is preferably 6 to 20, more preferably 6 to 10. Specific examples of the aromatic hydrocarbon ring are preferably benzene rings or naphthalene rings, more preferably benzene rings.

[0141] The number of ring atoms in the aromatic heterocycle constituting the divalent aromatic heterocyclic group is preferably 5 to 10, more preferably 5 or 6. Examples of heteroatoms contained in the aromatic heterocycle include nitrogen, oxygen, and sulfur atoms. Furthermore, the number of carbon atoms in the aromatic heterocycle is preferably 3 to 20, more preferably 3 to 10. Specific examples of aromatic heterocycles include pyridine rings, pyridazine rings, pyrimidine rings, pyrazine rings, triazine rings, thiophene rings, thiazole rings, and imidazole rings.

[0142] As A 1 and A 2 The divalent aromatic cyclic group represented is preferably a divalent aromatic hydrocarbon cyclic group, more preferably a divalent benzene cyclic group or a divalent naphthyl cyclic group.

[0143] As A 1 and A 2 The divalent alicyclic group can be represented by divalent aliphatic hydrocarbon cyclic groups and divalent aliphatic heterocyclic groups.

[0144] The aliphatic hydrocarbon ring constituting the divalent aliphatic hydrocarbon cyclic group can be either a monocyclic or polycyclic ring.

[0145] The number of ring atoms 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 aliphatic hydrocarbon rings include cyclopentane, cyclohexane, cycloheptane, cyclooctane, norbornene, and adamantane. Among these, cyclopentane or cyclohexane rings are preferred.

[0146] The aliphatic heterocycle constituting the divalent aliphatic heterocyclic group can be either a monocyclic or polycyclic aliphatic ring.

[0147] Examples of heteroatoms contained in aliphatic heterocycles include nitrogen, oxygen, and sulfur atoms. The number of ring atoms in an aliphatic heterocycle is not particularly limited, but 5 to 10 is preferred. Specific examples of aliphatic heterocycles include oxetane rings, oxetane rings, piperidine rings, and piperazine rings. Furthermore, aliphatic heterocycles can be substances in which the -CH2- group constituting the ring is replaced by -CO-, for example, phthalimide rings.

[0148] As A 1 and A 2 The substituents that can be present are not particularly limited; for example, alkyl groups can be listed.

[0149] sp 1 and sp 2 Each independently represents at least one -CH2- that can be -O-, -CO-, or -NR. X - or -S-substituted alkylene groups having 1 to 12 carbon atoms, R X It represents a hydrogen atom or an alkyl group (preferably an alkyl group with 1 to 6 carbon atoms).

[0150] As sp 1 and sp 2 Preferably, at least one -CH2- can be -O-, -CO-, or -NR. X An alkylene group having 1 to 8 carbon atoms that can be replaced by - or -S-, more preferably, at least one -CH2- can be -O-, -CO-, or -NR. X - or -S-substituted alkylene groups with 1 to 6 carbon atoms.

[0151] m and n each independently represent integers from 1 to 10, more preferably from 1 to 8, even more preferably from 1 to 6, and especially preferably from 2 to 6.

[0152] In equation (1), P 1 and P 2 Hydrogen atoms or monovalent substituents can be listed.

[0153] P 1 and P 2 At least one of them preferably represents a polymerizable group, and more preferably both represent polymerizable groups. Furthermore, the polymerizable groups described above can be listed as examples of polymerizable groups.

[0154] In equation (1), -(A) 1 -Z 1 ) m - indicates the structural part and - (Z) 2 -A 2 ) n -At least one of the structural regions indicated includes a cinnamic yl site selected from (specifically, -A) 1 -CR = CR-CO- or -A 2 -CR=CR-CO-), chalconite site (specifically, -A) 1 -CR=CR-CO-A 1 -or-A 2 -CR=CR-CO-A 2 - indicates the region), the azobenzene region (specifically, -A 1 -N=NA 1 -or-A 2 -N=NA 2 -The part indicated) and the stilbene part (specifically, -A) 1 -CR=CR-A 1 -or-A 2 -CR=CR-A 2 At least one site from the group consisting of the -represented site. As a structural site containing a cinnamoyl site, it can be a -cinnamoyl site -O- (specifically, -A). 1 -CR=CR-CO-O- or -A 2 -CR = CR-CO-O- (the location represented by the given information).

[0155] Furthermore, in equation (1), when m is an integer greater than 2, there exist multiple Z. 1 Each other and multiple A 1 Each can be the same or different. Furthermore, when n is an integer greater than 2, there exist multiple Z's. 2 Each other and multiple A 2 They can be the same or different from each other.

[0156] In equations (E) and (F), Indicates the bonding location.

[0157] [Chemical Formula 2]

[0158] Examples of chiral agents A include, for instance, the photoreactive chiral agents described in paragraphs 0044 to 0047 of Japanese Patent Application Publication No. 2001-159709, the optically active compounds described in paragraphs 0019 to 0043 of Japanese Patent Application Publication No. 2002-179669, the optically active compounds described in paragraphs 0020 to 0044 of Japanese Patent Application Publication No. 2002-179633, the optically active compounds described in paragraphs 0016 to 0040 of Japanese Patent Application Publication No. 2002-179670, the optically active compounds described in paragraphs 0017 to 0050 of Japanese Patent Application Publication No. 2002-179668, and the optically active compounds described in paragraphs 0018 to 0051 of Japanese Patent Application Publication No. 2002-180051. The optically active compounds described in paragraph 0044, the optically active isosorbide derivatives described in paragraphs 0016 to 0055 of Japanese Patent Application Publication No. 2002-338575, the photoreactive optically active compounds described in paragraphs 0023 to 0032 of Japanese Patent Application Publication No. 2002-080478, the photoreactive chiral agents described in paragraphs 0019 to 0029 of Japanese Patent Application Publication No. 2002-080851, the optically active compounds described in paragraphs 0022 to 0049 of Japanese Patent Application Publication No. 2002-179681, the optically active compounds described in paragraphs 0015 to 0044 of Japanese Patent Application Publication No. 2002-33, and the optically active compounds described in paragraphs 0015 to 0044 of Japanese Patent Application Publication No. 2002-33 The optically active polyesters described in paragraphs 0015-0050 of Japanese Patent Application Publication No. 8668, the binaphthyl derivatives described in paragraphs 0019-0041 of Japanese Patent Application Publication No. 2003-055315, the optically active fulgide compounds described in paragraphs 0008-0043 of Japanese Patent Application Publication No. 2003-073381, the optically active isosorbide derivatives described in paragraphs 0015-0057 of Japanese Patent Application Publication No. 2003-306490, the optically active isosorbide derivatives described in paragraphs 0015-0041 of Japanese Patent Application Publication No. 2003-313187, and the optically active isosorbide derivatives described in paragraphs 0015-0041 of Japanese Patent Application Publication No. 2003-313187. The optically active isosorbide derivatives described in paragraphs 0015-0049 of Japanese Patent Application Publication No. 2003-313188, the optically active isomannitol derivatives described in paragraphs 0015-0057 of Japanese Patent Application Publication No. 2003-313189, the optically active polyester / amides described in paragraphs 0015-0052 of Japanese Patent Application Publication No. 2003-313292, the optically active compounds described in paragraphs 0012-0053 of Japanese Patent Application Publication No. WO2018 / 194157, and the optically active compounds described in paragraphs 0020-0049 of Japanese Patent Application Publication No. 2002-179682.

[0159] (Chiral agent B)

[0160] The composition of the present invention contains chiral agent B.

[0161] Chiral agent B is a chiral agent of HTP that does not change due to exposure.

[0162] Here, a chiral agent whose HTP does not change due to exposure refers to a chiral agent that does not produce a photoreaction that would cause a change in HTP when exposed to light with a wavelength of 350 nm or higher. Specifically, this refers to a chiral agent that does not have photoisomerization groups or photoreactive groups that are photoreactive when exposed to light with a wavelength of 350 nm or higher.

[0163] Chiral agent B is not particularly restricted as long as it satisfies formula (F1). It can be a chiral agent that induces a helix in the opposite direction to that of chiral agent A, or it can be a chiral agent that induces a helix in the same direction as that of chiral agent A. Preferably, chiral agent B induces a helix in the opposite direction to that of chiral agent A. That is, for example, if the helix induced by chiral agent A is to the left, the helix induced by chiral agent B will be to the right.

[0164] Chiral agent B preferably has polymerizable groups.

[0165] The types of polymerizable groups are not particularly limited, but functional groups capable of addition polymerization are preferred, polymerizable olefinic unsaturated groups or cyclic polymerizable groups are more preferred, and (meth)acryloyl, vinyl, styrene or allyl are even more preferred.

[0166] When the chiral agent B has polymerizable groups, the number of polymerizable groups contained in each molecule is preferably 1 to 6, more preferably 2 to 4, and even more preferably 2.

[0167] Chiral agent B can be either liquid crystal or non-liquid crystal. Chiral agent B typically contains asymmetric carbon atoms. Alternatively, chiral agent B can be an axially chiral compound or a surface chiral compound that does not contain asymmetric carbon atoms.

[0168] As chiral agent B, known chiral agents can be used.

[0169] As chiral agent B, the compound represented by formula (2) is preferred.

[0170] Equation (2) P 3 -sp 3 -(A 3 -Z 3 ) p -L 2 -(Z 4 -A 4 )q -sp 4 -P 4

[0171] In equation (2), L 2 L in equation (1) 1 The meanings are the same, and the preferred methods are also the same.

[0172] In equation (2), A 3 and A 4 With A in equation (1) 1 The meanings are the same, and the preferred methods are also the same.

[0173] In equation (2), sp 3 and sp 4 With sp in equation (1) 1 The meanings are the same, and the preferred methods are also the same.

[0174] In equation (2), P 3 and P 4 P in equation (1) 1 The meanings are the same, and the optimization methods are also the same. Preferred P 3 and P 4 At least one of them represents a polymerizable group, and more preferably both represent polymerizable groups. In addition, the polymerizable groups mentioned above can be listed as polymerizable groups.

[0175] In equation (2), p and q have the same meaning as m in equation (1), and the preferred method is also the same.

[0176] In equation (2), Z 3 and Z 4 With Z in equation (1) 1 The meanings are the same.

[0177] As Z 3 and Z 4 The divalent linking group represented is preferably -O-, -S-, -CHRCHR-, -OCHR-, -CO-, -SO-, -SO2-, -COO-, -CO-S-, -O-CO-O-, -CO-NR-, -SCHR-, -SO-CHR-, -SO2-CHR-, -CF2O-, -CF2S-, -OCHRCHRO-, -SCHRCHRS-, -SO-CHRCHR-SO-, -SO2-CHRCHR-SO2-, -COO-CHRCHR-, -OCO-CHRCHR-, -COO-CHR- or -OCO-CHR-, more preferably -O-, -CO-, -COO- or -CO-NR-.

[0178] R represents a hydrogen atom, a cyano group, or an alkyl group having 1 to 10 carbon atoms. Furthermore, when multiple Rs are present in the formula, these Rs can be the same or different from each other.

[0179] There are multiple Z in the formula. 3 In the case of multiple Z 3 They can be the same or different. Furthermore, there are multiple Z's in the formula. 4 In the case of multiple Z 4 They can be the same or different.

[0180] <Physical properties of chiral agent A and chiral agent B>

[0181] The molar absorptivity of chiral agent A is not particularly limited, but the molar absorptivity at the wavelength of the light irradiated in step 3 of the manufacturing method of the present invention described later is preferably 100 to 100,000 L / (mol·cm), more preferably 500 to 50,000 L / (mol·cm).

[0182] In addition, as mentioned above, chiral agent A is preferably a chiral agent whose HTP changes when exposed to light with a wavelength of 350 nm or higher (preferably 350 to 370 nm).

[0183] In the composition of the present invention, from the viewpoint of easily controlling the orientation state of the polymerizable liquid crystal compound, the lower limit of the total content of chiral agent A and chiral agent B relative to the total mass of the polymerizable liquid crystal compound in the composition 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. The upper limit relative to the total mass of the polymerizable liquid crystal compound in the composition is preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less.

[0184] From the viewpoint of easily controlling the orientation state of the liquid crystal compound, the content of chiral agent A is preferably 5 to 95% by mass, more preferably 10 to 90% by mass, relative to the total content of chiral agent A and chiral agent B.

[0185] The lower limit of the content of chiral agent A in the composition of the present invention 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, relative to the total solid content of the composition. The upper limit 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, relative to the total solid content of the composition.

[0186] The lower limit of the content of chiral agent B in the composition of the present invention, relative to the total solids content of the composition, 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 content of chiral agent B in the composition, relative to the total solids content of the composition, 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.

[0187] The lower limit of the concentration of chiral agent A relative to the polymerizable liquid crystal compound (the content of chiral agent A relative to the polymerizable liquid crystal compound (corresponding to a 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 chiral agent 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.

[0188] The lower limit of the concentration of chiral agent B relative to the polymerizable liquid crystal compound (the content of chiral agent 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 chiral agent B relative to the polymerizable liquid crystal compound (the content of chiral agent 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.

[0189] [Photopolymerization initiator]

[0190] The compositions of the present invention contain a photopolymerization initiator.

[0191] As polymerization initiators, well-known polymerization initiators can be listed, with photopolymerization initiators being preferred.

[0192] As a photopolymerization initiator, known photopolymerization initiators can be used.

[0193] The content of the photopolymerization initiator in the composition is not particularly limited, but it is preferably 0.01 to 20% by mass, more preferably 0.5 to 10% by mass, relative to the total solid content of the composition.

[0194] [Other ingredients]

[0195] The compositions of the present invention may contain other components besides those described above. Other components are not particularly limited, and examples include solvents, surfactants, orientation control agents, polymerizable monomers, adhesion improvers, crosslinking agents, polymerization inhibitors, antioxidants, ultraviolet absorbers, light stabilizers, colorants, and metal oxide particles.

[0196] <Solvent>

[0197] The compositions of the present invention may contain a solvent.

[0198] As a solvent, a solvent capable of dissolving each component of the composition is preferred, such as methyl ethyl ketone, cyclohexanone (Anone), and mixtures thereof.

[0199] When the composition contains a solvent, the amount of solvent in the composition is not particularly limited, but it is preferred that the concentration of the solid component of the composition is 20 to 30% by mass, more preferably 20 to 25% by mass.

[0200] <surfactants>

[0201] The compositions of the present invention may contain surfactants.

[0202] As surfactants, conventionally known compounds can be listed, including hydrocarbon surfactants, fluorinated surfactants, and silicone surfactants. From the viewpoint of improving environmental adaptability, surfactants that do not contain fluorine atoms are preferred. As surfactants, hydrocarbon surfactants or silicone surfactants are preferred. As fluorinated surfactants, examples include compounds described in paragraphs 0028 to 0056 of Japanese Patent Application Publication No. 2001-330725 and compounds described in paragraphs 0069 to 0126 of Japanese Patent Application Publication No. 2003-295212.

[0203] Surfactants can be used alone or in combination with two or more.

[0204] When the composition contains a surfactant, the surfactant content 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, relative to the total solid content of the composition.

[0205] <Orientation Control Agent>

[0206] Furthermore, the compositions of the present invention may contain additives (orientation control agents) that promote horizontal or vertical orientation to make the liquid crystal compound be in a horizontal or vertical orientation state.

[0207] Examples of orientation control agents include fluoro(meth)acrylate polymers described in paragraphs

[0018] to

[0043] of Japanese Patent Application Publication No. 2007-272185, compounds represented by formulas (I) to (IV) described in paragraphs

[0031] to

[0034] of Japanese Patent Application Publication No. 2012-203237, and compounds described in Japanese Patent Application Publication No. 2013-113913.

[0208] In addition, as an orientation control agent, it can be used alone or two or more at the same time.

[0209] When the composition contains an orientation control agent, the content of the orientation control agent is preferably 0.01 to 10% by mass, more preferably 0.01 to 5% by mass, and even more preferably 0.02 to 1% by mass, relative to the total mass of the polymerizable liquid crystal compound.

[0210] [Embodiments of the Compositions of the Invention]

[0211] Hereinafter, an example of an embodiment of the composition of the present invention will be described.

[0212] <The composition of the first embodiment>

[0213] The composition of the first embodiment contains a reference. Figure 1 A composition comprising chiral agent A1 and chiral agent B1 satisfying the structure of formula (F1) is described. Chiral agent A1 is a chiral agent whose HTP decreases due to exposure, and is a chiral agent that induces a left-handed helical direction before and after exposure. Furthermore, the HTP of chiral agent A1 before exposure is 1 μm. -1 The HTP (exposure saturation HTP) obtained through Experiment 1 is Y1μm. -1 And they have a relationship of X1 > Y1.

[0214] Chiral agent B1 is a chiral agent B whose HTP does not change upon exposure, and it is a chiral agent that induces a right-handed helical direction before and after exposure. The HTP of chiral agent B1 in the composition before and after exposure is Z1 μm. -1 Furthermore, the relationship between the concentration (addition amount) a1 of chiral agent A1 relative to the polymerizable liquid crystal compound and the concentration (addition amount) b1 of chiral agent B1 relative to the polymerizable liquid crystal compound was adjusted so that the absolute value of X1a1 > the absolute value of Z1b1.

[0215] like Figure 1 As shown in the left figure, in the cholesteric liquid crystal layer before exposure, chiral agent A1 is a left-handed helix, therefore the value of X1a1 is positive. On the other hand, chiral agent B1 is a right-handed helix, therefore the value of Z1b1 is negative. Furthermore, the sum of the two is X1a1 + Z1b1, which is positive. That is, the helical structure of the cholesteric liquid crystal layer before exposure becomes a left-handed helix. In addition, the pitch of the helical structure in the cholesteric liquid crystal layer before exposure is represented by the reciprocal of X1a1 + Z1b1. Next, if the cholesteric liquid crystal layer is subjected to exposure treatment, the HTP of chiral agent A1 decreases to Y1μm. -1This results in a relationship where the absolute value of Y1a1 < the absolute value of Z1b1. After exposure, the sum of the products of HTP and concentration of chiral agents A and B, i.e., Z1b1 + Y1a1, becomes negative. That is, the helical direction of the helical structure induced by chiral agents A1 and B1 becomes the opposite direction to the helical structure of the cholesteric liquid crystal layer before exposure. Furthermore, the pitch of the helical structure in the cholesteric liquid crystal layer after exposure is expressed as the reciprocal of Z1b1 + Y1a1. Moreover, the aforementioned cholesteric liquid crystal layer becomes X1a1 + Z1b1 = -(Z1b1 + Y1a1), exhibiting the same pitch before and after exposure. Expanding the above equation, it is expressed as 1 = -2Z1b1 / (X1 + Y1)a1. That is, when exhibiting the same pitch before and after exposure, the above relationship is satisfied. If 0.90 < -2Z1b1 / (X1+Y1)a1 < 1.10, the pitch deviation 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 the reflectivity is excellent when the cholesteric liquid crystal layer is formed by the manufacturing method of the present invention described later.

[0216] <The Composition of Embodiment 2>

[0217] like Figure 4 As shown, the composition of the second embodiment is a composition comprising chiral agent A2 and chiral agent B2 and satisfying the structure of formula (F1). Chiral agent A2 is a chiral agent whose HTP decreases due to exposure, and is a chiral agent that induces a right-handed helical direction before and after exposure. Furthermore, the HTP of chiral agent A2 before exposure is 2 μm. -1 The HTP obtained through Experiment 1 is Y2μm -1 And they have a relationship where the absolute value of X2 is greater than the absolute value of Y2.

[0218] Chiral agent B2 is a chiral agent B whose HTP does not change upon exposure, and it is a chiral agent that induces a left-handed helical direction before and after exposure. The HTP of chiral agent B2 in the composition before and after exposure is Z2μm. -1 Furthermore, the relationship between the concentration (addition amount) a2 of chiral agent A2 relative to the polymerizable liquid crystal compound and the concentration (addition amount) b2 of chiral agent B2 relative to the polymerizable liquid crystal compound was adjusted so that the absolute value of X2a2 > the absolute value of Z2b2.

[0219] like Figure 4As shown in the left figure, in the cholesteric liquid crystal layer before exposure, chiral agent A2 is a right-handed helix, therefore the value of X2a2 is negative. On the other hand, chiral agent B2 is a left-handed helix, therefore the value of Z2b2 is positive. Furthermore, the sum of the two is X2a2 + Z2b2, which is negative. That is, the helical structure of the cholesteric liquid crystal layer before exposure becomes a right-handed helix. Additionally, the pitch of the helical structure in the cholesteric liquid crystal layer before exposure is expressed as the reciprocal of X2a2 + Z2b2. Next, if the cholesteric liquid crystal layer is subjected to exposure treatment, the HTP of chiral agent A2 decreases to Y2μm. -1 This results in a relationship where the absolute value of Y2a2 < the absolute value of Z2b2. After exposure, the sum of the products of HTP and concentration of chiral agents A2 and B2, i.e., Z2b2 + Y2a2, becomes positive. That is, the helical direction of the helical structure induced by chiral agents A2 and B2 becomes the opposite direction to the helical structure of the cholesteric liquid crystal layer before exposure. Furthermore, the pitch of the helical structure in the cholesteric liquid crystal layer after exposure is expressed as the reciprocal of Z2b2 + Y2a2. Moreover, the cholesteric liquid crystal layer becomes -(X2a2 + Z2b2) = Z2b2 + Y2a2, exhibiting the same pitch before and after exposure. Expanding the above equation, it is expressed as 1 = -2Z2b2 / (X2 + Y2)a2. That is, when exhibiting the same pitch before and after exposure, the above relationship is satisfied. If 0.90 < -2Z2b2 / (X2+Y2)a2 < 1.10, the pitch deviation 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 the reflectivity is excellent when the cholesteric liquid crystal layer is formed by the manufacturing method of the present invention described later.

[0220] <The Composition of the Third Embodiment>

[0221] like Figure 5 As shown, the composition of the third embodiment is a composition comprising chiral agent A3 and chiral agent B3 and satisfying the structure of formula (F1). Chiral agent A3 is a chiral agent whose HTP decreases due to exposure, and is a chiral agent that induces a left-handed helix before exposure and a right-handed helix after exposure. Furthermore, the HTP of chiral agent A3 before exposure is 3 μm. -1 The HTP obtained through Experiment 1 has a Y3μm value. -1 And they have a relationship where the absolute value of X3 is less than the absolute value of Y3.

[0222] Chiral agent B3 is a chiral agent B whose HTP does not change upon exposure, and it is a chiral agent that induces a left-handed helical direction before and after exposure. The HTP of chiral agent B3 in the composition before and after exposure is Z3μm. -1Furthermore, the concentration (addition amount) of chiral agent A3 relative to the polymerizable liquid crystal compound was adjusted to a3 by mass, and the concentration (addition amount) of chiral agent B3 relative to the polymerizable liquid crystal compound was adjusted to b3 by mass.

[0223] like Figure 5 As shown in the left figure, in the cholesteric liquid crystal layer before exposure, chiral agent A3 is a left-handed helix, therefore the value of X3a3 is positive. Furthermore, chiral agent B3 is also a left-handed helix, therefore the value of Z3b3 is positive. The sum of the two is X3a3 + Z3b3, which is also positive. That is, the helical structure of the cholesteric liquid crystal layer before exposure becomes a left-handed helix. In addition, the pitch of the helical structure in the cholesteric liquid crystal layer before exposure is represented by the reciprocal of X3a3 + Z3b3. Next, if the cholesteric liquid crystal layer is exposed, the helical induction direction of chiral agent A3 reverses to the right, and the HTP decreases to Y3μm. -1 The absolute value of Y3a3 is greater than the absolute value of Z3b3. After exposure, the sum of the products of the HTP and concentration of chiral agents A3 and B3, i.e., Z3b3 + Y3a3, becomes negative. That is, the helical direction of the helical structure induced by chiral agents A3 and B3 becomes the opposite direction to the helical structure of the cholesteric liquid crystal layer before exposure. In addition, the pitch of the helical structure in the cholesteric liquid crystal layer after exposure is expressed as the reciprocal of Z3b3 + Y3a3. Moreover, the cholesteric liquid crystal layer becomes X3a3 + Z3b3 = -(Z3b3 + Y3a3), exhibiting the same pitch before and after exposure. Expanding the above formula, it is expressed as 1 = -2Z3b3 / (X3 + Y3)a3. That is, when exhibiting the same pitch before and after exposure, the above relationship is satisfied. If 0.90 < -2Z3b3 / (X3+Y3)a3 < 1.10, the pitch deviation 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 the reflectivity is excellent when the cholesteric liquid crystal layer is formed by the manufacturing method of the present invention described later.

[0224] <The Composition of Embodiment 4>

[0225] like Figure 6 As shown, the composition of the fourth embodiment is a composition comprising chiral agent A4 and chiral agent B4 and satisfying the structure of formula (F1). Chiral agent A4 is a chiral agent whose HTP increases with exposure and is a chiral agent that induces a left-handed helical direction before and after exposure. Furthermore, the HTP of chiral agent A4 before exposure is 4 μm. -1 The HTP obtained through Experiment 1 has a Y4μm value. -1 And they have a relationship where the absolute value of X4 is less than the absolute value of Y4.

[0226] Chiral agent B4 is a chiral agent B whose HTP does not change upon exposure and induces a right-handed helical orientation before and after exposure. The HTP of chiral agent B4 in the composition before and after exposure is Z4μm. -1 Furthermore, the concentration (addition amount) of chiral agent A4 relative to the polymerizable liquid crystal compound was adjusted to a4 mass, and the concentration (addition amount) of chiral agent B4 relative to the polymerizable liquid crystal compound was adjusted to b4 mass.

[0227] like Figure 6 As shown in the left figure, in the cholesteric liquid crystal layer before exposure, chiral agent A4 is a left-handed helix, therefore the value of X4a4 is positive. On the other hand, chiral agent B4 is a right-handed helix, therefore the value of Z4b4 is negative. Furthermore, the sum of the two is X4a4 + Z4b4, which is negative. That is, the helical structure of the cholesteric liquid crystal layer before exposure becomes a right-handed helix. In addition, the pitch of the helical structure in the cholesteric liquid crystal layer after exposure is expressed as the reciprocal of X2a2 + Z2b2. Next, if the cholesteric liquid crystal layer is subjected to exposure treatment, the HTP of chiral agent A4 increases to Y4μm. -1 This results in a relationship where the absolute value of Y4a4 > the absolute value of Z4b4. After exposure, the sum of the products of HTP and concentration of chiral agents A4 and B4, i.e., Z4b4 + Y4a4, becomes positive. That is, the helical direction of the helical structure induced by chiral agents A4 and B4 becomes the opposite direction to the helical structure of the cholesteric liquid crystal layer before exposure. Furthermore, the pitch of the helical structure in the cholesteric liquid crystal layer after exposure is expressed as the reciprocal of Z4b4 + Y4a4. Moreover, the cholesteric liquid crystal layer becomes -(X4a4 + Z4b4) = Z4b4 + Y4a4, exhibiting approximately the same pitch before and after exposure. Expanding the above equation, it is expressed as 1 = -2Z4b4 / (X4 + Y4)a4. That is, when exhibiting the same pitch before and after exposure, the above relationship is satisfied. If 0.90 < -2Z4b4 / (X4+Y4)a4 < 1.10, the pitch deviation 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 the reflectivity is excellent when the cholesteric liquid crystal layer is formed by the manufacturing method of the present invention described later.

[0228] From the viewpoint of superior reflectivity, the value of -2Zb / (X+Y)a in formula (F1) of the composition of the present invention is preferably 0.94 to 1.06, more preferably 0.94 to 1.04, and even more preferably 0.97 to 1.03.

[0229] [Method for manufacturing the cholesteric liquid crystal layer of the present invention]

[0230] The following describes the method for manufacturing the cholesteric liquid crystal layer of the present invention (the manufacturing method of the present invention).

[0231] The manufacturing method of the present invention comprises the following steps 1 to 5 in sequence.

[0232] Step 1: Step of forming a composition layer of the composition of the present invention on a support.

[0233] Step 2: The step of orienting the polymeric liquid crystal compound in the above-mentioned composition layer

[0234] Step 3: Under conditions where the oxygen concentration is 1% by volume or higher, irradiate the above-mentioned composition layer from the side opposite to the above-mentioned support with light of a wavelength capable of changing the HTP of chiral agent A.

[0235] Step 4: The step of heating the above-mentioned composition layer.

[0236] Step 5: Step of curing the above-mentioned composition layer to fix the orientation state of the polymeric liquid crystal compound.

[0237] The cholesteric liquid crystal layer obtained by the manufacturing method of the present invention described above has a cholesteric liquid crystal phase with a helical direction originating from the cholesteric liquid crystal phase before exposure formed on the support side, and a cholesteric liquid crystal layer with a helical direction originating from the cholesteric liquid crystal phase after exposure formed on the side opposite to the support. Furthermore, the pitches of the two cholesteric liquid crystal phases formed along the thickness direction are approximately the same. That is, it becomes a cholesteric liquid crystal layer having two cholesteric liquid crystal phases with approximately the same pitch and different helical directions along the thickness direction.

[0238] The following describes each step of the manufacturing method of the present invention.

[0239] [Process 1]

[0240] Step 1 is the step of forming a composition layer of the composition of the present invention on a support. By performing this step, a composition layer for light irradiation treatment, which will be described later, can be formed. Furthermore, the composition of the present invention has already been described.

[0241] <Support>

[0242] The support is not particularly limited as long as it can support the composite layer.

[0243] As a support, a transparent support is preferred. Furthermore, a transparent support refers to a support with a visible light transmittance of 60% or more, preferably 80% or more, and more preferably 90% or more.

[0244] The retardation value (Rth(550)) of the support in the thickness direction at a wavelength of 550 nm is not particularly limited, but is preferably -110 to 110 nm, more preferably -80 to 80 nm.

[0245] 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.

[0246] The preferred material for forming the support is a polymer with excellent optical properties, transparency, mechanical strength, thermal stability, moisture shielding properties, and isotropy.

[0247] Examples of polymer films that can be used as supports include cellulose acylated 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, polypropylene films such as polymethyl methacrylate, polyurethane films, polycarbonate films, polysulfone films, polyether films, polymethylpentene films, polyetherketone films, (meth)acrylonitrile films, and films of polymers having an alicyclic structure (norbornene resins (ARTON: product name, manufactured by JSR Corporation.), amorphous polyolefins (ZEONEX: product name, manufactured by Zeon Corporation))).

[0248] Among them, triacetyl cellulose, polyethylene terephthalate or polymers with alicyclic structure are preferred as materials for polymer films, and triacetyl cellulose is more preferred.

[0249] The support may contain various additives (e.g., optical anisotropy modifiers, wavelength dispersion modifiers, microparticles, plasticizers, UV protectants, degradation inhibitors, and stripping agents).

[0250] The thickness of the support is not particularly limited, but is preferably 10–200 μm, more preferably 10–100 μm, and even more preferably 20–90 μm. Furthermore, the support can be composed of multiple layers stacked together. To improve the adhesion between the support and the layers disposed thereon, the surface of the support can be subjected to surface treatment (e.g., glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, and flame treatment).

[0251] Furthermore, an adhesive layer (base coat) can be applied to the support.

[0252] Furthermore, in order to impart lubrication to the support during the conveying process or to prevent the back side from sticking to the surface after winding, a polymer layer containing 5 to 40% by mass of inorganic particles with an average particle size of about 10 to 100 nm can be disposed on one side of the support.

[0253] The support can also be a so-called pseudo-support. That is, after implementing the manufacturing method of the present invention, the support can be peeled off from the cholesteric liquid crystal layer.

[0254] Furthermore, the surface of the support can be directly subjected to a friction treatment. That is, a support that has undergone a friction treatment can also be used. The direction of the friction treatment is not particularly limited, and the optimal direction can be appropriately selected according to the desired orientation of the polymerizable liquid crystal compound.

[0255] Friction processing is a widely used method for liquid crystal alignment in LCDs (liquid crystal displays). Specifically, it involves rubbing the surface of a support in a constant direction using materials such as paper, gauze, felt, rubber, nylon fibers, or polyester fibers to achieve alignment.

[0256] An orientation membrane can be placed on the support.

[0257] Orientation films can be formed by methods such as triboelectric treatment of organic compounds (preferably polymers), tilted evaporation of inorganic compounds, formation of layers with microgrooves, or accumulation of organic compounds (e.g., ω-trisanoic acid, dioctadecylmethylammonium chloride, and methyl stearate, etc.) based on the Langmuir-Blodgett process (LB film).

[0258] Furthermore, it is also known that alignment films can generate alignment functions by applying an electric field, a magnetic field, or irradiation with light (preferably polarized light).

[0259] The orientation film is preferably formed by friction treatment of the polymer.

[0260] Examples of polymers contained in the orientation film include methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohol and modified polyvinyl alcohol, poly(N-hydroxymethylacrylamide), polyesters, polyimides, vinyl acetate copolymers, carboxymethyl cellulose, and polycarbonates, as described in paragraph 0022 of Japanese Patent Application Publication No. 8-338913. Furthermore, silane coupling agents can also be used as polymers.

[0261] Water-soluble polymers are preferred (e.g., poly(N-hydroxymethylacrylamide), carboxymethyl cellulose, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol, etc.), gelatin or polyvinyl alcohol or modified polyvinyl alcohol are more preferred, and polyvinyl alcohol or modified polyvinyl alcohol is even more preferred.

[0262] As described above, the alignment film can be formed by coating a solution containing the aforementioned polymer as the alignment film forming material and any additive (e.g., crosslinking agent) onto a support, followed by heating and drying (to crosslink it) and then rubbing it.

[0263] <Steps of Process 1>

[0264] In step 1, a composition layer comprising the above-described components is formed, but the steps are not particularly limited. For example, methods of coating the composition of the present invention onto a support and performing drying treatment as needed (hereinafter also simply referred to as the "coating method") and other methods of forming the composition layer and transferring it onto the support can be listed. Among these, the coating method is preferred from the viewpoint of productivity.

[0265] The coating method is described in detail below.

[0266] As a composition used in the coating method, the compositions of the present invention described herein can be used.

[0267] The coating method is not particularly limited; for example, wire-wound bar coating, extrusion coating, direct gravure coating, reverse gravure coating, and die coating can be listed.

[0268] Additionally, if necessary, a drying process can be performed on the coating film applied to the support after the coating composition is applied. By performing the drying process, the solvent can be removed from the coating film.

[0269] The thickness of the coating 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.

[0270] [Process 2]

[0271] Step 2 is a step of orienting the polymeric liquid crystal compound in the composition layer. By performing this step, the polymeric liquid crystal compound in the composition layer is oriented into a cholesteric liquid crystal phase. That is, as... Figure 7 As shown, through step 2, a composition layer 12 of polymeric liquid crystal compound LC oriented in a cholesteric liquid crystal is formed on the support 10. Furthermore, Figure 7 This is a schematic diagram of the cross-section of the support 10 and the composition layer 12.

[0272] Step 2 is preferably a step of subjecting the composition layer to heat treatment (heat curing treatment) to orient the polymeric liquid crystal compound in the composition layer.

[0273] The optimal conditions for heat treatment can be selected based on the polymerizable liquid crystal compound used.

[0274] Among these, the heating temperatures are mostly between 25 and 250°C, even more so between 40 and 150°C, and even more so between 50 and 130°C.

[0275] The heating time is typically 0.1 to 60 minutes, with 0.2 to 5 minutes being more common.

[0276] The orientation state of the polymeric liquid crystal compound obtained through step 2 changes depending on the HTP and concentration of chiral agent A and chiral agent B.

[0277] The absolute value of the average HTP of the chiral agent in the composition layer formed by step 2 is preferably 10.0 μm. -1 The above, preferably 15.0μm -1 The above further optimizes the 20.0μm size. -1 That's all. The upper limit isn't specifically restricted, but 250μm is acceptable. -1 The following situations are more common, with 200μm being the preferred size. -1 Below, 100μm is more preferred. -1 the following.

[0278] Furthermore, when the absolute values ​​of the average HTP of chiral agent A and chiral agent B in the composition layer are within the above-mentioned range, typically, through step 2, the polymerizable liquid crystal compound in the composition can achieve cholesteric orientation.

[0279] [Process 3]

[0280] Step 3 is a step after step 2, in which the composition layer is irradiated with light of a wavelength that can change the HTP of chiral agent A under conditions where the oxygen concentration is 1% by volume or higher.

[0281] The mechanism of this process will be explained below using the accompanying drawings.

[0282] like Figure 7 As shown, in step 3, under the condition that the oxygen concentration is 1% by volume or more, the direction from the side of the support 10 opposite to the side of the composition layer 12 ( Figure 7 The direction of the hollow arrow in the image is used for illumination. Additionally, in... Figure 7 In this process, light irradiation is applied from the support 10 side, but it can also be applied from the composition layer 12 side.

[0283] At this point, if we compare the lower region 12A on the support 10 side of the composition layer 12 with the upper region 12B on the opposite side of the support 10 side, the surface of the upper region 12B is on the air side, therefore the oxygen concentration in the upper region 12B is high, and the oxygen concentration in the lower region 12A is low. Therefore, if the composition layer 12 is irradiated with light, the polymerization of the polymerizable liquid crystal compound is easily carried out in the lower region 12A, thereby fixing the orientation state of the polymerizable liquid crystal compound. In addition, chiral agent A is also present in the lower region 12A, and chiral agent A is also photosensitive, thereby changing the HTP. However, since the orientation state of the polymerizable liquid crystal compound is fixed in the lower region 12A, even if heat treatment is performed with light irradiation in step 3 (described later) or step 5 is performed on the composition layer that has been irradiated with light in step 3, the orientation state of the polymerizable liquid crystal compound will not change.

[0284] Furthermore, due to the high oxygen concentration in the upper region 12B, the polymerization of the polymerizable liquid crystal compound is hindered by oxygen even under light irradiation, making polymerization difficult. Moreover, chiral agent A is also present in the upper region 12B, thus chiral agent A is photosensitive, causing a change in HTP. Therefore, if step 4, which involves heat treatment of the composition layer subjected to light irradiation as described later, is performed, the orientation state of the polymerizable liquid crystal compound changes according to the altered HTP.

[0285] That is, by performing light irradiation in step 3, the orientation state of the polymerizable liquid crystal compound can be easily fixed in the region (lower region) on the support side of the composition layer. However, in the region (upper region) on the side of the composition layer opposite to the support side, it is difficult to fix the orientation state of the polymerizable liquid crystal compound, and the HTP of chiral agent A changes due to exposure.

[0286] Step 3 is performed under conditions where the oxygen concentration is 1% by volume or more (e.g., under atmospheric conditions). From the viewpoint that regions with different orientation states in the cholesteric liquid crystal layer readily form polymerizable liquid crystal compounds, the oxygen concentration is preferably 2% by volume or more, and more preferably 5% by volume or more. The upper limit is not particularly limited, and 100% by volume can be cited as an example.

[0287] 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. The lower limit is not particularly limited, but from the viewpoint of curing the polymerizable liquid crystal compound, it is preferably 0.1 seconds or more, more preferably 0.2 seconds or more.

[0288] The preferred light irradiation dose in step 3 is 300 mJ / cm. 2 Below, 250 mJ / cm is more preferred. 2The following is a further optimization of 200 mJ / cm 2 The following is not particularly limited in terms of the lower limit, but from the viewpoint of curing polymerizable liquid crystal compounds, 1 mJ / cm is preferred. 2 Above, 5mJ / cm is preferred. 2 above.

[0289] In addition, the light irradiation in step 3 is preferably carried out at 15 to 70°C (preferably 25 to 50°C).

[0290] The light used for irradiation can be any light that is photosensitive to chiral agent A. That is, the light used for irradiation is not particularly limited as long as it is an active light source or radiation that changes the HTP of chiral agent A. Examples include the bright-line spectrum of mercury lamps, far-ultraviolet light represented by excimer lasers, extreme ultraviolet light, X-rays, ultraviolet light, and electron beams. Among these, ultraviolet light is preferred.

[0291] Furthermore, the light used in the illumination is preferably light with a wavelength of 350 nm or higher (preferably 350-370 nm).

[0292] When applying ultraviolet light, it is preferable to use LEDs with a peak emission wavelength of 365nm.

[0293] Additionally, heat treatment can be performed during light irradiation in step 3. The heat treatment performed during light irradiation in step 3 is the same as in the subsequent step 4, and will be explained in the subsequent step 4.

[0294] [Process 4]

[0295] Step 4 is a step of heat treatment of the composition layer.

[0296] From the viewpoint that it is easy to form a predetermined cholesteric liquid crystal layer, step 4 is preferably a heat treatment process performed at a higher temperature than that performed during light irradiation in step 3.

[0297] By implementing step 4, the orientation state of the polymeric liquid crystal compound changes in the region where the HTP of chiral agent A changes in the composition layer after light irradiation in step 3. More specifically, step 4 is a step of oriented the polymeric liquid crystal compound in the composition layer that was not fixed during light irradiation in step 3 by performing a heat treatment (preferably at a higher temperature than during light irradiation in step 3) on the composition layer after light irradiation in step 3.

[0298] The mechanism of this process will be explained below using the accompanying drawings.

[0299] As mentioned above, if for Figure 7When the composition layer 12 shown is irradiated with light in step 3, the orientation state of the polymerizable liquid crystal compound in the lower region 12A is fixed. In contrast, polymerization of the polymerizable liquid crystal compound is difficult to occur 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 the change in the HTP of chiral agent A. If such a change in the HTP of chiral agent A occurs, the force for twisting the polymerizable liquid crystal compound in the upper region 12B changes compared to the state before light irradiation in step 3. In addition, the change in the twisting force of chiral agent A and chiral agent B in the cholesteric liquid crystal phase after exposure treatment is explained in the composition of the present invention.

[0300] The HTP of chiral agent A changes due to exposure treatment, causing the helical direction of the cholesteric liquid crystal phase in the upper region 12B to become opposite to that in the lower region 12A. That is, when the helical direction of the cholesteric liquid crystal phase in the lower region 12A is to the left, the helical direction of the cholesteric liquid crystal phase in the upper region 12B becomes to the right.

[0301] The upper region 12B is exposed (illuminated) by light irradiation in process 3, such as... Figure 1 As shown, when the HTP of chiral agent A decreases due to exposure, in Figure 7 In the upper region 12B, the dextrorotatory HTP derived from chiral agent B is relatively strong.

[0302] Therefore, if the composition layer 12 after light irradiation in step 3, where such an average HTP change occurs, is subjected to the heat treatment of step 4 to promote the reorientation of the polymerizable liquid crystal compound, then in the upper region 12B, the twisting 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, the polymerization of the polymerizable liquid crystal compound occurs during light irradiation in step 3, and the orientation state of the polymerizable liquid crystal compound is fixed, so no reorientation of the polymerizable liquid crystal compound occurs.

[0303] As described above, by performing step 4, a cholesteric liquid crystal layer is formed having cholesteric liquid crystal phases with approximately the same pitch and different helical directions along the thickness direction of the composition layer.

[0304] Additionally, the upper section shows that it will include Figure 1The combination of chiral agent A1 and chiral agent B1 shown (the composition of the first embodiment) is an example applicable to the manufacturing method of the present invention. However, even when using the composition of other embodiments, by performing step 4, a cholesteric liquid crystal layer having a cholesteric liquid crystal phase having approximately the same pitch and different helical directions along the thickness direction of the composition layer can be formed.

[0305] The heat treatment in step 4 is preferably carried out at a higher temperature than that in step 3 when exposed to light.

[0306] The temperature difference between the heating treatment in step 4 and the temperature during light irradiation in step 3 is preferably 5°C or more, more preferably 10-110°C, and even more preferably 20-110°C.

[0307] The preferred temperature for the heat treatment in step 4 is higher than the temperature during light irradiation in step 3, and is a temperature that orients the unfixed polymeric liquid crystal compound in the composition layer. More specifically, 40 to 250°C is more common, 50 to 150°C is even more common, temperatures exceeding 50°C but below 150°C are even more common, and temperatures between 60 and 130°C are particularly common.

[0308] The heating time for step 4 is mostly between 0.01 and 60 minutes, and even more often between 0.03 and 5 minutes.

[0309] Furthermore, it can also replace step 4 and be used to perform heat treatment during light irradiation in step 3.

[0310] In addition, if heat treatment is performed during light irradiation in step 3, the heat treatment can be performed before light irradiation or during light irradiation.

[0311] When heat treatment is performed during light irradiation in step 3, the heating temperature and heating time are as described above.

[0312] [Process 5]

[0313] Step 5 is a process of fixing the orientation state of the polymeric liquid crystal compound by performing a curing treatment on the composition layer after the heat treatment in step 4 (i.e., after the polymeric liquid crystal compound is reoriented). Through step 5, a cholesteric liquid crystal layer can be formed in which cholesteric liquid crystal phases with approximately the same pitch and different helical directions are fixed along the thickness direction of the composition layer.

[0314] The curing method is not particularly limited, and examples include photocuring and thermal curing. Among these, photocuring is preferred, and ultraviolet irradiation is even more preferred.

[0315] Ultraviolet (UV) light sources can be used for UV irradiation. Furthermore, wavelength cutoff filters can be used during UV irradiation.

[0316] The amount of light (e.g., ultraviolet radiation) is not particularly limited, but is generally preferred to be 100–800 mJ / cm². 2 about.

[0317] The environment for light irradiation is not particularly restricted; it can be carried out in air or in an inert atmosphere. In particular, light irradiation is preferably carried out under conditions where the oxygen concentration is less than 1% by volume.

[0318] When photocuring is performed as the curing process in step 5, the temperature conditions during photocuring are not particularly limited, as long as the temperature is maintained at the orientation state of the polymeric liquid crystal compound after the heat treatment in step 4.

[0319] The temperature difference between the heat treatment in step 4 and the photocuring treatment in step 5 is preferably within 100°C, and more preferably within 80°C.

[0320] In addition, it is preferable that the temperature of the heat treatment in step 4 is the same as the temperature of the light curing treatment in step 4, or that the temperature of the light curing treatment in step 5 is a lower temperature.

[0321] In the cholesteric liquid crystal layer obtained by curing, the orientation state of the polymeric liquid crystal compound has been fixed.

[0322] Furthermore, in this specification, the "fixed" state refers to the state in which the orientation of the liquid crystal compound is maintained, which is the most typical and preferred state. However, it is not limited to this; more specifically, it is preferred to maintain a fixed orientation state in a temperature range that is typically 0–50°C, or more harshly -30–70°C, without fluidity within the layer, and without any change in orientation morphology due to external fields or forces.

[0323] Furthermore, in cholesteric liquid crystal layers, the composition in the final layer no longer needs to exhibit liquid crystal properties.

[0324] 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. Furthermore, the thickness of the cholesteric liquid crystal is particularly preferably 1.8 μm or less, and most preferably 1.3 μm or less.

[0325] The cholesteric liquid crystal layer formed by the above method, having fixed cholesteric liquid crystal phases, has two cholesteric liquid crystal phases with approximately the same pitch and opposite helical directions along the thickness direction. Specifically, the cholesteric liquid crystal layer formed by the above method has a region (hereinafter also referred to as "Region 1") where a cholesteric liquid crystal phase with a helical direction exhibiting either a right-handed or left-handed orientation is fixed along the thickness direction, and a region (hereinafter also referred to as "Region 2") where a cholesteric liquid crystal phase with a helical direction opposite to that of Region 1 is fixed.

[0326] The selective reflection center wavelengths derived from the cholesteric liquid crystal phases in each region are roughly the same.

[0327] Furthermore, each cholesteric liquid crystal phase in the first and second regions typically has a helical axis that is substantially parallel to the thickness direction.

[0328] For example, the cholesteric liquid crystal layer can be a cholesteric liquid crystal layer consisting of a first region formed by fixing a cholesteric liquid crystal phase that reflects dextrorotatory blue light along the thickness direction and a second region formed by fixing a cholesteric liquid crystal phase that reflects levorotatory blue light; it can also be a cholesteric liquid crystal layer consisting of a first region formed by fixing a cholesteric liquid crystal phase that reflects dextrorotatory green light along the thickness direction and a second region formed by fixing a cholesteric liquid crystal phase that reflects levorotatory green light; or it can be a cholesteric liquid crystal layer consisting of a first region formed by fixing a cholesteric liquid crystal phase that reflects dextrorotatory red light along the thickness direction and a second region formed by fixing a cholesteric liquid crystal phase that reflects levorotatory red light.

[0329] Furthermore, in this specification, the selection of the reflection center wavelength refers to setting T as the minimum value of the transmittance in the material (component) to be targeted. min In the case of (%), it exhibits the half-value transmittance expressed by the following formula: T 1 / 2 The average value of the two wavelengths (%).

[0330] The formula for calculating half-value transmittance is: T 1 / 2 =100-(100-T min )÷2

[0331] Furthermore, in the visible light spectrum, light with wavelengths above 420nm and below 500nm is blue light (B light), light with wavelengths above 500nm and below 600nm is green light (G light), and light with wavelengths above 600nm and below 700nm is red light (R light).

[0332] [Cholesteric liquid crystal layer]

[0333] The cholesteric liquid crystal layer of the present invention is a cholesteric liquid crystal layer formed from the composition of the present invention.

[0334] The cholesteric liquid crystal layer of the present invention is a cholesteric liquid crystal layer formed by fixing a cholesteric liquid crystal phase, preferably having a structure in which two cholesteric liquid crystal phases have approximately the same pitch and opposite helical directions along the thickness direction. That is, the cholesteric liquid crystal layer of the present invention preferably has a structure in which a cholesteric liquid crystal phase exhibiting a helical direction of either right-handed or left-handed (first region) is fixed along the thickness direction, and a cholesteric liquid crystal phase having a helical direction opposite to that of the first region (second region). The selective reflection center wavelengths derived from the cholesteric liquid crystal phases in each region are approximately the same. Furthermore, each cholesteric liquid crystal phase in the first and second regions typically has a helical axis approximately parallel to the thickness direction.

[0335] 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. Furthermore, the thickness of the cholesteric liquid crystal is particularly preferably 1.8 μm or less, and most preferably 1.3 μm or less.

[0336] [Reflective film]

[0337] The above-mentioned cholesteric liquid crystal layer can be used as a reflective film.

[0338] Furthermore, the reflective film formed from the aforementioned cholesteric liquid crystal layer, when assembled in a windshield, can preferably be used as a combiner for a head-up display (e.g., an in-vehicle head-up display system).

[0339] Example

[0340] The present invention will now be described in further detail with reference to embodiments. The materials, amounts, proportions, processing contents, and processing steps shown in the following embodiments can be appropriately modified without departing from the spirit of the invention. Therefore, the scope of the present invention should not be interpreted as limiting by the embodiments shown below.

[0341] [Example 1]

[0342] [Preparation of liquid crystal composition a]

[0343] Liquid crystal composition a was prepared by mixing the components shown below.

[0344] ――――――――――――――――――――――――――――――――

[0345] Composition of liquid crystal composition a

[0346] ――――――――――――――――――――――――――――――――

[0347] • 100.0 parts by weight of the following polymeric liquid crystal compound LC1

[0348] • Photopolymerization initiator (OXE01, manufactured by BASF) 3.0 parts by weight

[0349] • 1.2 parts by weight of compound C (adhesion improver)

[0350] • 0.1 parts by weight of the following compound D (orientation control agent)

[0351] • 10.8 parts by mass of the following compound X1 (corresponding to chiral agent A)

[0352] • 2.6 parts by mass of the following compound Y1 (corresponding to chiral agent B)

[0353] Mixed solvents

[0354] (Methyl ethyl ketone (MEK) / Cyclohexanone (mass ratio 70 / 30))

[0355] The concentration of the solid component is 20% by mass.

[0356] ――――――――――――――――――――――――――――――――

[0357] -Polymerizable liquid crystal compound LC1-

[0358] [Chemical Formula 3]

[0359] Furthermore, the Δn (representing the refractive index anisotropy at a wavelength of 550 nm) of the aforementioned polymeric liquid crystal compound LC1 is 0.15.

[0360] -Compound C-

[0361] [Chemical Formula 4]

[0362] -compound D-

[0363] [Chemical Formula 5]

[0364] -Compound X1-

[0365] [Chemical Formula 6]

[0366] -Compound Y1-

[0367] [Chemical Formula 7]

[0368] [Determination of HTP in chiral agent A]

[0369] <Pre-exposure HTP and saturated HTP of compound X1>

[0370] The following describes the measurement procedures for pre-exposure HTP and exposure-saturated HTP of compound X1 corresponding to chiral agent A.

[0371] (Preparation of the composition for evaluation)

[0372] An evaluation composition with the following composition was prepared.

[0373] ---------------- ...

[0374] Evaluation composition

[0375] ---------------- ...

[0376] Compound X1: 5 parts by mass

[0377] • The above-mentioned polymeric liquid crystal compound LC-1: 100 parts by weight

[0378] • Mixed solvent (MEK (methyl ethyl ketone) / cyclohexanone = 90 / 10 (mass ratio)): The concentration of the solid components in the composition is 30% by mass.

[0379] ---------------- ...

[0380] [Fabrication of a support with an alignment membrane]

[0381] A polyimide alignment film material SE-130 (manufactured by Nissan Chemical Corporation) was coated onto a cleaned glass support to form a film. After calcining the obtained film, a support with an alignment film was produced by friction treatment.

[0382] (Determination of HTP)

[0383] Determination of HTP in Compound X1 before Exposure

[0384] On the friction-treated surface of the support with the above-mentioned oriented film, 40 μL of the above-mentioned evaluation composition was spin-coated at 1500 rpm for 10 seconds, and the obtained coating was then heated (dried and cured) at 90°C for 1 minute to form a composition layer.

[0385] For the obtained composite layer, the center reflection wavelength was measured at room temperature (23°C), and the HTP (initial HTP (pre-exposure HTP)) was calculated according to the following formula (F5).

[0386] Formula (F5): HTP = (Average refractive index of the liquid crystal compound) / {(Concentration of chiral agent relative to liquid crystal compound (mass%)) × (Central reflection wavelength)} [μm -1 ] Determination of Exposure Saturation HTP in Compound X1 Next, using an LED lamp (ULW365-21701-5F manufactured by Acroedge Co., Ltd.) with a peak emission wavelength of 365nm, the exposure was increased from 10mJ / cm². 2 Every 10mJ / cm 2 Simultaneously, the composition layer was exposed at more than 15 locations at different positions, and the HTP of each exposed portion was determined. More specifically, the center reflection wavelength was measured at each of the above-mentioned exposed portions, and the calculation was performed in the same manner as the above formula (F5), thereby calculating the HTP of each of the above-mentioned exposed portions.

[0387] Next, based on the HTP-exposure correlation curve obtained by plotting the points corresponding to HTP and exposure amount for each exposure portion on an orthogonal coordinate system with HTP as the vertical axis and exposure amount as the horizontal axis, the optimal method for increasing exposure amount by 10 mJ / cm was determined. 2 The HTP whose HTP change rate before and after the increase is within 1% (exposure saturation HTP). In addition, this exposure saturation HTP is equivalent to "the HTP at the exposure level when HTP does not change" in compound X1 (i.e., Y in formula (F1)).

[0388] The above-mentioned HTP change rate is obtained by the following formula (F6).

[0389] Formula (F6): HTP change rate = |{(HTP before increased exposure) - (HTP after increasing exposure by 10mJ / cm²)} 2 (HTP after exposure) / (HTP before exposure increase) × 100 | [%] The results of the above measurements confirmed that the pre-exposure HTP (equivalent to the X value in formula (F1)) of compound X1 was 30 μm. -1 The exposure saturation HTP (equivalent to the Y value in equation (F1)) is 0 μm. -1 In addition, compound X1 induces a left-handed helix.

[0390] [Determination of HTP in chiral agent B]

[0391] <HTP of compound Y1>

[0392] Compound X1 was replaced with compound Y1. Otherwise, the HTP of compound Y1, equivalent to chiral agent B, was determined using the same method as for determining the pre-exposure HTP of compound X1 (equivalent to chiral agent A). The results of these measurements confirmed that the pre-exposure HTP of compound Y1 (equivalent to the Z value in formula (F1)) was -60 μm. -1 Furthermore, compound Y1 induces a right-handed helix. Moreover, compound Y1 is a chiral agent that does not produce a photoreaction that would cause a change in HTP even when exposed to light with wavelengths above 350 nm; the HTP after exposure treatment to change the HTP of chiral agent A also exhibits the same value as the HTP before exposure.

[0393] [Fabrication of reflective film]

[0394] Liquid crystal composition a was coated onto a TAC (triacetyl cellulose) film with an oriented film to achieve a dried film thickness of 1.3 μm. After coating, the film was left to stand at room temperature for 15 seconds and then subjected to a heat treatment (drying and curing) at 60°C for 30 seconds. Then, the film was irradiated with 60 mJ / cm² from the side opposite to the TAC film at 40°C under atmospheric conditions. 2 The sample was then subjected to ultraviolet light (wavelength 365 nm) and heat-treated again for 30 seconds at 60 °C (curing). Then, it was subjected to heat treatment (aging) at 50 °C with an oxygen concentration below 100 ppm by volume using a metal halide lamp with a cutoff wavelength below 330 nm, achieving a heat output of 300 mJ / cm³. 2 The cholesteric liquid crystal phase is fixed by exposure using a cumulative light intensity method. This results in the sequential formation of a cholesteric liquid crystal layer on the TAC film side, consisting of two cholesteric phases with approximately the same pitch but different helical directions. This also forms a two-layer reflective layer with a reflective layer (layer 1) that reflects left-handed circularly polarized light and a reflective layer (layer 2) that reflects right-handed circularly polarized light. In other words, a two-layer reflective layer is formed, with a left-handed circularly polarized light reflective layer (layer 1) on the lower layer side and a right-handed circularly polarized light reflective layer (layer 2) on the upper layer side.

[0395] [Example 2]

[0396] [Preparation of liquid crystal composition d]

[0397] Liquid crystal composition d was prepared by mixing the components shown below.

[0398] ――――――――――――――――――――――――――――――――

[0399] Composition of liquid crystal composition d

[0400] ――――――――――――――――――――――――――――――――

[0401] · 100.0 parts by weight of the above polymerizable liquid crystal compound LC1

[0402] • Photopolymerization initiator (OXE01, manufactured by BASF) 3.0 parts by weight

[0403] • 1.2 parts by weight of compound C (adhesion improver) mentioned above.

[0404] • 0.1 parts by mass of the above compound D (orientation control agent)

[0405] • 12.9 parts by mass of the following compound X2 (corresponding to chiral agent A)

[0406] • 1.7 parts by mass of the above compound Y1 (corresponding to chiral agent B)

[0407] Mixed solvents

[0408] (Methyl ethyl ketone (MEK) / Cyclohexanone (mass ratio 70 / 30))

[0409] The concentration of the solid component is 20% by mass.

[0410] ――――――――――――――――――――――――――――――――

[0411] -Compound X2-

[0412] [Chemical Formula 8]

[0413] [Determination of HTP in chiral agent A]

[0414] <Pre-exposure HTP and saturated HTP of compound X2>

[0415] The pre-exposure HTP and exposure saturation HTP of compound X2 were measured using the above steps. The results confirmed that the pre-exposure HTP of compound X2 (corresponding to the X value in formula (F1)) was 21 μm. -1 The exposure saturation HTP (corresponding to the Y value in equation (F1)) is -6.5μm. -1 In addition, compound X2 induces a left-handed helix before exposure and a right-handed helix after exposure.

[0416] [Fabrication of reflective film]

[0417] The liquid crystal composition a was changed to liquid crystal composition d, but the reflective film of Example 2 was fabricated using the same steps as in Example 1. Specifically, a cholesteric liquid crystal layer, in which two cholesteric phases with approximately the same pitch but different helical directions are immobilized, was sequentially formed on the TAC film side. This formed a two-layer reflective layer with 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 stacked on top of each other. That is, a two-layer reflective layer was formed with a left-handed circularly polarized light reflective layer (first layer) on the lower layer side and a right-handed circularly polarized light reflective layer (second layer) on the upper layer side.

[0418] [Comparative Example 1 (a double-layer liquid crystal layer with different alignment layers)]

[0419] The liquid crystal composition a was changed to the optical anisotropic layer forming composition (3) described in Example 3 of International Publication No. 2021 / 033631. Otherwise, a reflective film was prepared by the same method as in Example 1.

[0420] [Comparative Example 2 (by bonding layers)]

[0421] [Preparation of liquid crystal composition b]

[0422] Liquid crystal composition b was prepared by mixing the components shown below.

[0423] ――――――――――――――――――――――――――――――――

[0424] Composition of liquid crystal composition b

[0425] ――――――――――――――――――――――――――――――――

[0426] · 100.0 parts by weight of the above polymerizable liquid crystal compound LC1

[0427] • Photopolymerization initiator (OXE01, manufactured by BASF) 3.0 parts by weight

[0428] • 1.2 parts by weight of compound C (adhesion improver) mentioned above.

[0429] • 0.1 parts by mass of the above compound D (orientation control agent)

[0430] • 5.8 parts by mass of the above compound X1 (equivalent to chiral agent A)

[0431] Mixed solvents

[0432] (Methyl ethyl ketone (MEK) / Cyclohexanone (mass ratio 70 / 30))

[0433] The concentration of the solid component is 20% by mass.

[0434] ――――――――――――――――――――――――――――――――

[0435] [Preparation of liquid crystal composition c]

[0436] Liquid crystal composition c was prepared by mixing the components shown below.

[0437] ――――――――――――――――――――――――――――――――

[0438] Composition of liquid crystal composition c

[0439] ――――――――――――――――――――――――――――――――

[0440] · 100.0 parts by weight of the above polymerizable liquid crystal compound LC1

[0441] • Photopolymerization initiator (OXE01, manufactured by BASF) 3.0 parts by weight

[0442] • 1.2 parts by weight of compound C (adhesion improver) mentioned above.

[0443] • 0.1 parts by mass of the above compound D (orientation control agent)

[0444] • 3.0 parts by mass of the above compound Y1 (corresponding to chiral agent B)

[0445] Mixed solvents

[0446] (Methyl ethyl ketone (MEK) / Cyclohexanone (mass ratio 70 / 30))

[0447] The concentration of the solid component is 20% by mass.

[0448] ――――――――――――――――――――――――――――――――

[0449] [Fabrication of reflective film]

[0450] Liquid crystal composition b was coated onto a TAC film with an oriented film to a dried film thickness of 0.65 μm. After coating, the film was left to stand at room temperature for 15 seconds and then heated at 60°C for 30 seconds. Then, it was heated at 50°C with an oxygen concentration below 100 ppm by volume and subjected to a metal halide lamp with a cutoff wavelength below 330 nm at a concentration of 300 mJ / cm². 2The cholesteric liquid crystal phase is fixed by exposure using the cumulative light amount method, thereby forming the first layer (a reflective layer for left-handed circularly polarized light) on the TAC film.

[0451] Then, using liquid crystal composition c, a second layer (a reflective layer for right-handed circularly polarized light) was formed on the TAC film using the same steps.

[0452] Next, the TAC film with the first layer and the TAC film with the second layer obtained above were bonded together by TAC film side adhesion. Specifically, an adhesive (SK-2057, manufactured by Soken Chemical & Engineering Co., Ltd.) was applied to the side of the first layer (left-hand circularly polarized light reflective layer) of the TAC film to form an adhesive layer, and then bonded together by TAC film adhesion of the second layer (right-hand circularly polarized light reflective layer).

[0453] [Various reviews]

[0454] [Measurement of reflectivity of reflective film]

[0455] Using a spectrophotometer (JASCO Corporation, V-670), the reflectivity of the obtained reflective film was measured in the 850-950 nm range by incident P-polarized light at a 5° angle relative to the normal direction of the film, and evaluated according to the following evaluation criteria. The results are shown in Table 1.

[0456] (Evaluation Criteria)

[0457] A: Reflectivity is over 95%.

[0458] B: Reflectivity is above 75% and below 95%.

[0459] C: Reflectivity is above 55% and below 75%.

[0460] D: Reflectivity less than 55%

[0461] [Determination of uneven thickness of reflective film]

[0462] In each of the 64 sub-regions obtained by equally dividing the largest square obtainable on the surface of the second layer of the reflective film into 8 sections both longitudinally and transversely, the reflective film is cut through the center of each sub-region and parallel to the friction direction. The thickness d1 of the first layer (bottom layer) and the thickness d2 of the second layer (top layer) are measured based on the exposed cross-section. The maximum value Z of the proportion Z of thickness d1 in the total layer thickness (d1+d2) (=d1 / (d1+d2)) is calculated. max With minimum value Z min The ratio (Z) max / Zmin ).

[0463] The obtained values ​​were differentiated and evaluated based on the following evaluation criteria. The results are shown in Table 1.

[0464] (Evaluation Criteria)

[0465] A: 1 or higher and less than 1.05

[0466] B: 1.05 or higher and less than 1.1

[0467] C: 1.1 or higher and less than 1.15

[0468] D: 1.15 and above

[0469] Table 1 is shown below.

[0470] In addition, the definitions of X, Y, Z, a and b in “-2Zb / (X+Y)a” in the table are the same as the definitions of X, Y, Z, a and b in equation (F1).

[0471] Furthermore, in the “Preparation Method” column of the table, the case of forming a cholesteric liquid crystal layer (reflective layer) with a two-layer structure by coating the composition together is referred to as “composition”, and the case of forming by bonding is referred to as “bonding”.

[0472] [Table 1]

[0473] It was confirmed that the reflective layer (cholesterol liquid crystal layer) of the embodiment has excellent reflectivity and minimal film thickness inhomogeneity.

[0474] Symbol Explanation

[0475] 2-Support, 4-Composition layer, EX1, EX2, EX3-Exposure, HTP1, HTP2, HTP3-Helical twisting force, ΔT-Change in HTP2 and HTP3, 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 torsional force changes with exposure, a chiral agent B whose helical torsional force does not change with exposure, and a photopolymerization initiator. The composition satisfies the following formula (F1). Equation (F1): 0.90 < -2Zb / (X+Y)a < 1.10 In the formula, X represents the helical torsion force of the chiral agent A before exposure. Y is the helical torsion force obtained by the following test 1 of the chiral agent A. Z represents the helical torsion force of the chiral agent B. 'a' represents 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. in, In equation (F1), X, Y, and Z become negative values ​​when a right-handed spiral is induced, and positive values ​​when a left-handed spiral is induced. In addition, the unit of the helical torsion force is μm. -1 The concentration is expressed in % by mass. Experiment 1: The chiral agent A is exposed using a light-emitting diode with a peak emission wavelength of 365 nm. The helical torsion force of the chiral agent A at each exposure is measured, and the helical torsion force at the exposure at which the helical torsion force no longer changes is set 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 formula, L 1 The term represents a divalent linker formed by removing two hydrogen atoms from the structure represented by formula (D), the divalent linker represented by formula (E), or the divalent linker represented by formula (F). In formulas (E) and (F), Indicates the bonding location, Z 1 and Z 2 Each can independently represent a single bond or a divalent linker. A 1 and A 2 Each can independently represent a divalent aromatic ring group that may have substituents or a divalent alicyclic group that may have substituents. sp 1 and sp 2 Each independently represents at least one -CH2- that can be -O-, -CO-, or -NR. X - or -S-substituted alkylene groups having 1 to 12 carbon atoms, R X Indicates a hydrogen atom or an alkyl group. P 1 and P 2 Each can be listed independently as either a hydrogen atom or a monovalent substituent. m and n each independently represent integers from 1 to 10. [Chemical Formula 1] Wherein, -(A) 1 -Z 1 ) m - indicates the structural part and - (Z) 2 -A 2 ) n - At least one of the structural regions represented includes a region selected from the group consisting of a cinnamyl region, a chalcone region, an azobenzene region, and a stilbene region.

3. The composition according to claim 1 or 2, wherein, The chiral agent A undergoes a change in its helical torsion force when irradiated with light of wavelengths above 350 nm.

4. The composition according to claim 1 or 2, wherein, The polymeric liquid crystal compound has a Δn of 0.15 or higher.

5. A method for manufacturing a cholesteric liquid crystal layer, comprising the following steps: Step 1: Forming a composition layer of the composition according to claim 1 on a support; Step 2, oriented the polymeric liquid crystal compound in the composition layer; Step 3: Under conditions where the oxygen concentration is 1% by volume or higher, light of a wavelength that can change the helical torsion force of the chiral agent A is irradiated from the side of the composition layer opposite to the support. Step 4: Heating the composition layer; and Step 5 involves curing the composition layer to fix the orientation state of the polymeric 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 of claim 6.

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