Method for producing cholesteric liquid crystal layer, cholesteric liquid crystal layer, reflective film, laminated glass, head-up display system, and composition

Abstract

The present invention addresses a first problem of providing a method for producing a cholesteric liquid crystal layer, wherein said method can conveniently produce a cholesteric liquid crystal layer that is resistant to changes in the reflection spectrum when a heat treatment is performed in a state in which an adjacent layer is disposed on its surface. The present invention further addresses a second problem of providing a cholesteric liquid crystal layer, a reflective film, a laminated glass, a head-up display system, and a composition.　The method according to the present invention for producing a cholesteric liquid crystal layer comprises: a step 1 for forming a composition layer containing a polymerizable group-bearing liquid crystal compound, a first polymerizable chiral agent for which the helical twisting power is changed by irradiation with light, and a second polymerizable chiral agent; a step 2 for causing the orientation of the liquid crystal compound; a step 3 for carrying out, under prescribed conditions, irradiation with light of a wavelength that can change the helical twisting power of the first polymerizable chiral agent; and a step 4 for executing a curing treatment on the composition layer to form a cholesteric liquid crystal layer. The composition layer is subjected to a heat treatment between the step 3 and the step 4 or in the step 3.

Description

Method for manufacturing cholesteric liquid crystal layer, cholesteric liquid crystal layer, reflective film, laminated glass, head-up display system, and composition

[0001] The present invention relates to a method for producing a cholesteric liquid crystal layer, a cholesteric liquid crystal layer, a reflective film, a laminated glass, a head-up display system, and a composition.

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

[0003] Known head-up display systems include, for example, windshield glass incorporating a reflective film including a cholesteric liquid crystal layer that selectively reflects circularly polarized light. Furthermore, the cholesteric liquid crystal layer often comprises a laminate of multiple cholesteric liquid crystal layers with different central reflection wavelengths (in other words, different helical pitches derived from the liquid crystal compounds) to achieve a reflection spectrum with a wide reflection band spanning the visible range. Note that the manufacturing process for incorporating the reflective film into the windshield glass typically involves laminating the reflective film and the glass that constitutes the windshield glass via an adhesive layer (an optical clear adhesive (OCA) layer) or a heat seal layer, and then subjecting this laminate to a heat treatment.

[0004] For example, Patent Document 1 discloses a simple method for producing an optically anisotropic layer in which the alignment state of the liquid crystal compound is fixed and which has a plurality of regions in the thickness direction where the alignment state of the liquid crystal compound is different. More specifically, the method discloses a method for molding a laminate having two optically anisotropic layers made of rod-shaped liquid crystal compositions in a single coating step.

[0005] International Publication No. 2022 / 030266

[0006] The present inventors have studied a manufacturing method for collectively forming a cholesteric liquid crystal layer having a plurality of regions with different helical pitches along the thickness direction, with reference to the manufacturing method for an optically anisotropic layer described in Patent Document 1. As a result, they have found that when the obtained cholesteric liquid crystal layer is subjected to a heat treatment with an adjacent layer such as an adhesive layer or a heat seal layer disposed on the surface thereof, the reflection spectrum of the cholesteric liquid crystal layer changes before and after heating, and reflected light of the desired color may not be obtained.

[0007] Therefore, an object of the present invention is to provide a method for producing a cholesteric liquid crystal layer, which can easily produce a cholesteric liquid crystal layer that is less likely to undergo change in reflection spectrum when subjected to a heat treatment with an adjacent layer disposed on its surface. Another object of the present invention is to provide a cholesteric liquid crystal layer, a reflective film, laminated glass, a head-up display system, and a composition.

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

[0009] (1) A method for producing a cholesteric liquid crystal layer, comprising: Step 1 forming a composition layer containing a liquid crystal compound having a polymerizable group, a first polymerizable chiral agent whose helical twisting power changes upon light irradiation, and a second polymerizable chiral agent having a twisting power in the opposite direction to that of the first polymerizable chiral agent; Step 2 orienting the liquid crystal compound in the composition layer; Step 3 irradiating the composition layer with light of a wavelength that can change the helical twisting power of the first polymerizable chiral agent under conditions of an oxygen concentration of 1% by volume or more; and Step 4 curing the composition layer to fix the alignment state of the liquid crystal compound and form a cholesteric liquid crystal layer having a plurality of regions with different helical pitches along the thickness direction, wherein Step 5 heat-treating the composition layer between Steps 3 and 4, or further heat-treating the composition layer during light irradiation in Step 3. (2) A method for producing a cholesteric liquid crystal layer according to (1), wherein the first polymerizable chiral agent and the second polymerizable chiral agent each have two or more polymerizable groups. (3) The method for producing a cholesteric liquid crystal layer according to (1) or (2), wherein the first polymerizable chiral agent and the second polymerizable chiral agent contain a partial structure selected from the group consisting of an isosorbide partial structure, an isomannide partial structure, and a binaphthyl partial structure. (4) The method for producing a cholesteric liquid crystal layer according to any one of (1) to (3), wherein the first polymerizable chiral agent has a photoisomerizable double bond in the molecule. (5) The method for producing a cholesteric liquid crystal layer according to any one of (1) to (4), wherein the first polymerizable chiral agent contains a photoisomerizable moiety selected from the group consisting of a cinnamoyl moiety, a chalcone moiety, and a stilbene moiety. (6) The method for producing a cholesteric liquid crystal layer according to any one of (1) to (5), wherein the thickness of the cholesteric liquid crystal layer is 10 μm or less. (7) A cholesteric liquid crystal layer having a fixed cholesteric liquid crystal phase, the cholesteric liquid crystal layer having a plurality of regions with different helical pitches in the thickness direction, the cholesteric liquid crystal layer being a layer formed using a composition containing a liquid crystal compound having a polymerizable group, a first polymerizable chiral agent whose helical twisting force changes upon irradiation with light, and a second polymerizable chiral agent having a gyration in the opposite direction to that of the first polymerizable chiral agent. (8) A reflective film having the cholesteric liquid crystal layer according to (7).(9) A reflective film having, in this order, a first retardation layer, the cholesteric liquid crystal layer according to (7), and a second retardation layer. (10) The reflective film according to (9), which has an average reflectance of 15% or less at an incident angle of 5° and a wavelength of 400 to 800 nm. (11) The reflective film according to (9) or (10), which has an average transmittance of 50% or more at a wavelength of 380 to 420 nm. (12) Laminated glass having, in this order, a first glass plate, the reflective film according to any one of (8) to (11), and a second glass plate. (13) The laminated glass according to (12), which has a heat seal layer or an adhesive layer between the first glass plate and the reflective film or between the second glass plate and the reflective film. (14) Laminated glass having, in this order, a first glass plate, an interlayer film, a second glass plate, and the reflective film according to any one of (8) to (11). (15) The laminated glass according to (14), which has a heat seal layer or an adhesive layer between the second glass plate and the reflective film. (16) A head-up display system comprising a windshield glass made of the laminated glass according to any one of (12) to (15) and a projector that irradiates projection light onto the windshield glass. (17) The head-up display system according to (16), wherein the projector irradiates P-polarized projection light. (18) A composition comprising a liquid crystal compound having a polymerizable group, a first polymerizable chiral agent whose helical twisting power changes upon irradiation with light, and a second polymerizable chiral agent having a twisting power in the opposite direction to that of the first polymerizable chiral agent.

[0010] According to the present invention, there is provided a method for producing a cholesteric liquid crystal layer, which can easily produce a cholesteric liquid crystal layer that is less likely to undergo change in reflection spectrum when subjected to a heat treatment with an adjacent layer disposed on the surface thereof. The present invention also provides a cholesteric liquid crystal layer, a reflective film, a laminated glass, a head-up display system, and a composition.

[0011] 1 is a cross-sectional view of a composition layer for illustrating an example of step 2 of the method for producing a cholesteric liquid crystal layer of the present invention. －１ ) × concentration (mass%) and light irradiation dose (mJ / cm２ ) of the first polymerizable chiral agent and the second polymerizable chiral agent. －１ ) and light irradiation dose (mJ / cm ２ ) of the first polymerizable chiral agent and the second polymerizable chiral agent. －１ ) and light irradiation dose (mJ / cm ２ 1 is a schematic diagram of a graph plotting the relationship between the reflection intensity (Tc) and the reflection rate (Rc) of the reflection film; FIG. 2 is a schematic cross-sectional view showing an example of the configuration of a reflective film; FIG. 3 is a schematic cross-sectional view showing another example of the configuration of laminated glass; FIG. 4 is a schematic cross-sectional view showing another example of the configuration of a head-up display;

[0012] The present invention will be described in detail below. In this specification, a numerical range expressed using "to" means a range that includes the numerical values ​​before and after "to" as the lower and upper limits. First, the terms used in this specification will be described.

[0013] In the description of the production method in this specification, "light" means, unless otherwise specified, actinic rays or radiation, such as the bright line spectrum of a mercury lamp, far ultraviolet rays typified by excimer lasers, extreme ultraviolet rays (EUV light), X-rays, ultraviolet rays, and electron beams (EB). Of these, ultraviolet rays are preferred.

[0014] In the description of the present specification, except for the manufacturing method, "light" refers to visible light and natural light (unpolarized light) unless otherwise specified.

[0015] In this specification, "visible light" refers to light in the wavelength range of 380 to 780 nm. In addition, in this specification, unless otherwise specified, the measurement wavelength is 550 nm. Of visible light, light in the wavelength range of 420 to 490 nm is blue (B) light, light in the wavelength range of 495 to 570 nm is green (G) light, and light in the wavelength range of 620 to 750 nm is red (R) light. In this specification, "invisible light" refers to light in the wavelength range of less than 380 nm or more than 780 nm.

[0016] In this specification, the cholesteric liquid crystal phase is a phase having a periodic structure in which liquid crystal compounds are helically aligned, and the twist angle is 360° or more. When liquid crystal compounds are helically aligned in an optically anisotropic layer other than the cholesteric liquid crystal phase, the twist angle is preferably more than 0° and less than 360°.

[0017] In this specification, terms relating to angles such as "angles expressed by specific numerical values," "parallel," "horizontal," "vertical," and "orthogonal" include a generally acceptable error range in the relevant technical field unless otherwise specified. Specifically, this means that the error is within a range of ±10° or less from the exact angle. The error from the exact angle is preferably ±7° or less, and more preferably ±5° or less.

[0018] In this specification, the terms "same" and "entire surface" include a generally acceptable margin of error in the relevant technical field, unless otherwise specified.

[0019] In this specification, "visible light transmittance" refers to the visible light transmittance for an A-light source as defined in JIS (Japanese Industrial Standards) R 3212:2015 (Test Methods for Automotive Safety Glass). That is, the transmittance is determined by measuring the transmittance at each wavelength in the wavelength range of 380 to 780 nm using a spectrophotometer with an A-light source, and multiplying the transmittance at each wavelength by a weighting coefficient obtained from the wavelength distribution and wavelength interval of the CIE (Commission Internationale de l'Eclairage) photopic standard relative luminosity factor, and calculating a weighted average. When simply referring to "reflected light" or "transmitted light," this term is used to include scattered light and diffracted light.

[0020] In this specification, "P-polarized light" refers to polarized light that vibrates in a direction parallel to the plane of incidence of light, and "S-polarized light" refers to polarized light that vibrates in a direction perpendicular to the plane of incidence of light. Furthermore, "plane of incidence" refers to a plane that is perpendicular to a reflective surface (such as the surface of a windshield glass) and that includes the incident and reflected light rays. In P-polarized light, the plane of vibration of the electric field vector is parallel to the plane of incidence, while in S-polarized light, the plane of vibration of the electric field vector is perpendicular to the plane of incidence.

[0021] In this specification, the in-plane retardation (in-plane phase difference) is a value measured using an AxoScan manufactured by Axometrics. Unless otherwise specified, the measurement wavelength is 550 nm. The in-plane retardation is a value measured by irradiating light having a wavelength within the visible light wavelength range in the normal direction of the film.

[0022] In this specification, "projection image" means an image based on the projection of light from the projector being used, rather than the surrounding scenery such as the view ahead. A projection image is visually recognized by an observer as a virtual image that appears to appear beyond the windshield glass. In this specification, "screen image" means an image displayed on the drawing device of the projector, or an image drawn by the drawing device on an intermediate image screen or the like. A projection image is a virtual image, whereas a screen image is a real image. Note that both the image and the projection image may be a monochromatic image, a multi-color image of two or more colors, or a full-color image.

[0023] In this specification, the terms "first" and "second" in the terms "first glass sheet" and "second glass sheet" have no technical meaning and are used for convenience to distinguish between the two glass sheets. However, in the following description, when the laminated glass is used as a windshield glass in a vehicle, the first glass sheet will be described as being on the exterior side of the vehicle and the second glass sheet will be described as being on the interior side of the vehicle.

[0024] In this specification, the "solid content" of a composition refers to components that form a cholesteric liquid crystal layer formed using the composition, and when the composition contains a solvent (organic solvent, water, etc.), it refers to all components excluding the solvent. Furthermore, liquid components that form a cholesteric liquid crystal layer are also considered to be solid contents.

[0025] [Method for manufacturing a cholesteric liquid crystal layer] The method for manufacturing a cholesteric liquid crystal layer of the present invention (hereinafter referred to as the "manufacturing method of the present invention") comprises: Step 1 of forming a composition layer containing a liquid crystal compound having a polymerizable group (hereinafter also referred to as the "polymerizable liquid crystal compound"), a first polymerizable chiral agent whose helical twisting power changes upon light irradiation (hereinafter abbreviated as the "first polymerizable chiral agent"), and a second polymerizable chiral agent whose helical twisting power is opposite to that of the first polymerizable chiral agent (hereinafter abbreviated as the "second polymerizable chiral agent"); Step 2 of aligning the liquid crystal compound in the composition layer; Step 3 of irradiating the composition layer with light of a wavelength capable of changing the helical twisting power of the first polymerizable chiral agent under conditions of an oxygen concentration of 1% by volume or more; and Step 4 of curing the composition layer to fix the alignment state of the liquid crystal compound and form a cholesteric liquid crystal layer having a plurality of regions with different helical pitches along the thickness direction. Between the step 3 and the step 4, a step 5 of subjecting the composition layer to a heat treatment may be included, or in the step 3, the composition layer may be further subjected to a heat treatment during the light irradiation.

[0026] The cholesteric liquid crystal layer obtained by the manufacturing method of the present invention is unlikely to undergo a change in reflection spectrum when subjected to a heat treatment with an adjacent layer disposed on its surface. The following describes the characteristics of the manufacturing method of the present invention and its presumed mechanism of action.

[0027] First, one of the features of the manufacturing method of the present invention is that predetermined steps are carried out.

[0028] As will be described in detail later, in the present invention, first, the polymerizable liquid crystal compound in the composition layer is aligned (Step 2). Note that Step 2 typically forms a cholesteric liquid crystal layer. In Step 3, the oxygen concentration is low in a portion of the composition layer on the substrate (support member for the composition layer) side, and high in another portion of the surface opposite the substrate. Therefore, when such a composition layer is irradiated with light having a wavelength capable of changing the helical twisting power of the first polymerizable chiral agent, the helical twisting power of the first polymerizable chiral agent changes (e.g., photoisomerization or photodimerization) in the high-oxygen-concentration region, but polymerization of the polymerizable liquid crystal compound, first polymerizable chiral agent, and second polymerizable chiral agent is difficult to proceed due to oxygen inhibition, whereas polymerization of the polymerizable components, such as the polymerizable liquid crystal compound, first polymerizable chiral agent, and second polymerizable chiral agent, proceeds more easily in the low-oxygen-concentration region. Furthermore, in regions with low oxygen concentrations, although changes in the helical twisting power of the first polymerizable chiral agent (e.g., photoisomerization or photodimerization) occur, the rate of the polymerization reaction is faster, and as a result, the alignment state of the liquid crystal compound can be fixed before changes in the alignment state of the liquid crystal compound occur due to changes in the helical twisting power of the first polymerizable chiral agent. Then, by the curing treatment in step 4, the liquid crystal compound is fixed in regions where the oxygen concentration was high and the polymerization reaction did not proceed easily in step 3. As a result, a cholesteric liquid crystal layer is produced having a plurality of regions with different helical pitches along the thickness direction.

[0029] Another feature of the manufacturing method of the present invention is that the chiral agent has a polymerizable group. Based on recent studies, the present inventors have speculated that when an adjacent layer is placed on the surface of a cholesteric liquid crystal layer formed using a chiral agent without a polymerizable group and subjected to a heat treatment, the unfixed chiral agent present in the cholesteric liquid crystal layer migrates to the adjacent layer with a lower chiral agent concentration, resulting in a decrease in the volume of the cholesteric liquid crystal layer, thereby reducing the helical pitch and causing a change in the reflection spectrum. In the manufacturing method of the cholesteric liquid crystal layer of the present invention, polymerizable chiral agents, such as the first polymerizable chiral agent and the second polymerizable chiral agent, are used to fix the chiral agent in the cholesteric liquid crystal layer, so that even when an adjacent layer is placed on the surface of the cholesteric liquid crystal layer and subjected to a heat treatment, a change in the reflection spectrum is unlikely to occur.

[0030] Hereinafter, when a cholesteric liquid crystal layer is subjected to a heat treatment with an adjacent layer disposed on its surface, the fact that the reflection spectrum is less likely to change can also be referred to as the superior effect of the present invention.

[0031] Each step of the production method of the present invention will be described below.

[0032] [Step 1] Step 1 is a step of forming a composition layer containing a polymerizable liquid crystal compound, a first polymerizable chiral agent, and a second polymerizable chiral agent. By carrying out this step, a composition layer is formed that is subjected to a light irradiation treatment described later. Below, first, the materials used in this step will be described in detail, and then the procedure of the step will be described in detail.

[0033] <Chiral Agent> (First Polymerizable Chiral Agent) The composition layer of step 1 contains a first polymerizable chiral agent. The first polymerizable chiral agent has a polymerizable group and is a chiral agent whose helical twisting power changes upon irradiation with light. The first polymerizable chiral agent will be described in detail below. The helical twisting power (HTP) of a chiral agent is a factor that indicates the helical alignment ability, expressed by the following formula (A): Formula (A) HTP=1 / (helical pitch length (unit: μm)×concentration of chiral agent relative to liquid crystal compound (mass %)) [μm -1The helical pitch length refers to the length of the pitch P (=helical period) of the helical structure of a cholesteric liquid crystal phase, and can be measured by the method described on page 196 of Liquid Crystal Handbook (published by Maruzen Co., Ltd.).

[0034] The type of polymerizable group contained in the first polymerizable chiral agent is not particularly limited, but is preferably a functional group capable of addition polymerization, more preferably a polymerizable ethylenically unsaturated group or a ring-polymerizable group, and even more preferably a (meth)acryloyl group, a vinyl group, a styryl group, or an allyl group. The number of polymerizable groups contained in the first polymerizable chiral agent is not particularly limited, but is, for example, preferably 1 to 6, more preferably 2 to 4, and even more preferably 2.

[0035] The first polymerizable chiral agent may be liquid crystalline or non-liquid crystalline. The first polymerizable chiral agent generally contains an asymmetric carbon atom. The first polymerizable chiral agent may be an axially asymmetric compound or a planar asymmetric compound that does not contain an asymmetric carbon atom.

[0036] The first polymerizable chiral agent may be a chiral agent whose helical twisting power increases or decreases upon light irradiation. Among these, a chiral agent whose helical twisting power decreases upon light irradiation is preferred. In this specification, "increase and decrease in helical twisting power" refers to an increase or decrease when the initial helical direction of the first polymerizable chiral agent (before light irradiation) is defined as "positive." Therefore, even when the helical twisting power continues to decrease upon light irradiation and exceeds 0, the helical direction becomes "negative" (i.e., when a helical twist is induced in the opposite helical direction to the initial helical direction (before light irradiation)), this also falls under the category of a "chiral agent whose helical twisting power decreases."

[0037] Examples of the first polymerizable chiral agent include so-called photoreactive chiral agents. A photoreactive chiral agent has a chiral moiety and a photoreactive moiety that undergoes a structural change upon irradiation with light, and is, for example, a compound that significantly changes the twisting power of a liquid crystal compound depending on the amount of irradiation. Examples of photoreactive moieties that undergo a structural change upon irradiation with light include photochromic compounds (Kingo Uchida, Masahiro Irie, Chemical Industry, Vol. 64, p. 640, 1999; Kingo Uchida, Masahiro Irie, Fine Chemical, Vol. 28(9), p. 15, 1999). The structural change refers to decomposition, addition reaction, isomerization, racemization, [2+2] photocyclization, dimerization, and the like that occur upon irradiation of the photoreactive moiety with light, and the structural change may be irreversible. Examples of the chiral moiety include the asymmetric carbons described in Hiroyuki Nodaira, Chemistry Review, No. 22, Chemistry of Liquid Crystals, p. 73, 1994.

[0038] As the first polymerizable chiral agent, a compound having at least a photoisomerizable moiety is preferred, and the photoisomerizable moiety more preferably has a photoisomerizable double bond. As the photoisomerizable moiety having the photoisomerizable double bond, a cinnamoyl moiety, a chalcone moiety, an azobenzene moiety, or a stilbene moiety is preferred in that photoisomerization is likely to occur and the difference in helical twisting power before and after light irradiation is large, and a cinnamoyl moiety, a chalcone moiety, or a stilbene moiety is more preferred in that the absorption of visible light is small. Note that the photoisomerizable moiety corresponds to the photoreactive moiety that undergoes a structural change upon light irradiation as described above.

[0039] The first polymerizable chiral agent preferably has a trans-type photoisomerizable double bond, in terms of high initial (before light irradiation) helical twisting power and a larger change in helical twisting power upon light irradiation, and the first polymerizable chiral agent preferably has a cis-type photoisomerizable double bond, in terms of low initial (before light irradiation) helical twisting power and a larger change in helical twisting power upon light irradiation.

[0040] The first polymerizable chiral agent preferably has any partial structure selected from a binaphthyl partial structure, an isosorbide partial structure (a partial structure derived from isosorbide), and an isomannide partial structure (a partial structure derived from isomannide). The binaphthyl partial structure, the isosorbide partial structure, and the isomannide partial structure each refer to the following structures. In the binaphthyl partial structure, the portion where the solid line and the dashed line are parallel represents a single bond or a double bond. In the structures shown below, * represents a bond position.

[0041]

[0042] The first polymerizable chiral agent is preferably a compound represented by formula (CA): １ -sp １ - (A １ -Z １ ) ｍ -L １ -(Z ２ -A ２ ) ｎ -sp ２ -P ２ L １ represents a divalent linking group formed by removing two hydrogen atoms from the structure represented by formula (D) (a divalent linking group formed by removing two hydrogen atoms from the binaphthyl partial structure), a divalent linking group represented by formula (E) (a divalent linking group comprising the isosorbide partial structure), or a divalent linking group represented by formula (F) (a divalent linking group comprising the isomannide partial structure).

[0043] Z １ and Z ２ represents a single bond or a divalent linking group. １ and Z ２ Examples of the divalent linking group represented by the formula: ２ -, -COO-, -CO-S-, -O-CO-O-, -CO-NR-, -SCHR-, -SO-CHR-, -SO ２ -CHR-, -CF ２ O-, -CF ２S-, -OCHRCHRO-, -SCHRCHRS-, -SO-CHRCHR-SO-, -SO ２ -CHRCHR-SO ２ Preferably, R represents -, -CR=CR-CO-, -CR=CR-COO-, -CR=CR-OCO-, -CR=CR-CONR-, -CR=CR-COS-, -COO-CHRCHR-, -OCO-CHRCHR-, -COO-CHR-, -OCO-CHR-, -CR=CR-, -CR=N-, -N=CR-, -N=N-, -CR=N-N=CR-, -CF=CF-, or -C≡C-. R represents a hydrogen atom, a cyano group, or an alkyl group having 1 to 10 carbon atoms. When multiple Rs are present in the formula, the multiple Rs may be the same or different from one another. In the formula, Z １ If there are multiple Z １ may be the same or different. ２ If there are multiple Z ２ The Z may be the same or different from each other. １ and multiple Zs ２ It is preferable that at least one of the Z represents a divalent linking group selected from the group consisting of -CR=CR-CO-, -CR=CR-COO-, -CR=CR-OCO-, -CR=CR-CONR-, -CR=CR-COS-, -CR=CR-, -N=N-, and -CF=CF-; １ At least one of, and, and multiple Z ２ It is more preferable that at least one of the groups represented by the formula (I) represents a divalent linking group selected from the group consisting of -CR=CR-CO-, -CR=CR-COO-, -CR=CR-OCO-, -CR=CR-CONR-, -CR=CR-COS-, -CR=CR-, -N=N-, and -CF=CF-.

[0044] A １ and A ２ each independently represents a divalent aromatic ring group which may have a substituent or a divalent alicyclic group which may have a substituent.

[0045] A １ and A ２Examples of the divalent aromatic ring group represented by the formula (I) include a divalent aromatic hydrocarbon ring group and a divalent aromatic heterocyclic group. The aromatic hydrocarbon ring constituting the divalent aromatic hydrocarbon ring group may be either a monocyclic or polycyclic ring. The number of carbon atoms in the aromatic hydrocarbon ring is preferably 6 to 20, and more preferably 6 to 10. Specific examples of the aromatic hydrocarbon ring are preferably a benzene ring or a naphthalene ring, and more preferably a benzene ring.

[0046] The number of ring members in the aromatic heterocycle constituting the divalent aromatic heterocyclic group is preferably 5 to 10, and more preferably 5 or 6. Examples of heteroatoms contained in the aromatic heterocycle include a nitrogen atom, an oxygen atom, and a sulfur atom. The number of carbon atoms in the aromatic heterocycle is preferably 3 to 20, and more preferably 3 to 10. Specific examples of the aromatic heterocycle include a pyridine ring, a pyridazine ring, a pyrimidine ring, a pyrazine ring, a triazine ring, a thiophene ring, a thiazole ring, and an imidazole ring.

[0047] A １ and A ２ The divalent aromatic ring group represented by the formula (I) is preferably a divalent aromatic hydrocarbon ring group, more preferably a divalent benzene ring group or a divalent naphthalene ring group.

[0048] A １ and A ２ Examples of the divalent alicyclic group represented by the formula (I) include a divalent aliphatic hydrocarbon ring group and a divalent aliphatic heterocyclic group. The aliphatic hydrocarbon ring constituting the divalent aliphatic hydrocarbon ring group may be either a monocyclic or polycyclic ring. The number of ring members in the aliphatic hydrocarbon ring is preferably 3 to 20, more preferably 3 to 10, and even more preferably 5 or 6. Specific examples of the aliphatic hydrocarbon ring include a cyclopentane ring, a cyclohexane ring, a cycloheptane ring, a cyclooctane ring, a norbornene ring, and an adamantane ring. Of these, a cyclopentane ring or a cyclohexane ring is preferred.

[0049] The aliphatic heterocycle constituting the divalent aliphatic heterocyclic group may be either a monocycle or a polycycle. Examples of heteroatoms contained in the aliphatic heterocycle include a nitrogen atom, an oxygen atom, and a sulfur atom. The number of ring members in the aliphatic heterocycle is not particularly limited, but is preferably 5 to 10. Specific examples of the aliphatic heterocycle include an oxolane ring, an oxane ring, a piperidine ring, and a piperazine ring. The aliphatic heterocycle may be a ring containing -CH ２ The - may be substituted with -CO-, such as a phthalimide ring.

[0050] A １ and A ２ The substituent that may be possessed by is not particularly limited, and examples thereof include an alkyl group.

[0051] sp １ and sp ２ each independently represents at least one —CH ２ - is -O-, -CO-, -NR Ｘ represents an alkylene group having 1 to 12 carbon atoms which may be substituted with - or -S-. Ｘ represents a hydrogen atom or an alkyl group (preferably an alkyl group having 1 to 6 carbon atoms). １ and sp ２ At least one -CH ２ - is -O-, -CO-, -NR Ｘ It preferably represents an alkylene group having 1 to 8 carbon atoms which may be substituted with - or -S-, and at least one -CH ２ - is -O-, -CO-, -NR Ｘ More preferably, it represents an alkylene group having 1 to 6 carbon atoms which may be substituted with - or -S-.

[0052] m and n each independently represent an integer of 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, and particularly preferably 2 to 6.

[0053] In formula (CA), P １ and P ２ is a hydrogen atom or a monovalent substituent. １ and P ２At least one of the groups represents a polymerizable group, and it is preferred that both groups represent polymerizable groups. Examples of the polymerizable group include the above-mentioned polymerizable groups.

[0054] However, -(A １ -Z １ ) m- and -(Z ２ -A ２ )n-, a cinnamoyl moiety (specifically, -A １ -CR=CR-CO- or -A ２ a moiety represented by -CR=CR-CO-), a chalcone moiety (specifically, -A １ -CR=CR-CO-A １ -or-A ２ -CR=CR-CO-A ２ -), an azobenzene moiety (specifically, -A １ -N=N-A １ -or-A ２ -N=N-A ２ -), and a stilbene moiety (specifically, -A １ -CR=CR-A １ -or-A ２ -CR=CR-A ２ The structural moiety containing a cinnamoyl moiety includes at least one moiety selected from the group consisting of -cinnamoyl moiety-O- (specifically, -A １ -CR=CR-CO-O- or -A ２ -CR=CR-CO-O-) may be used.

[0055] In addition, in formula (CA), when m is an integer of 2 or more, a plurality of Z １ A and multiple A １ When n is an integer of 2 or more, a plurality of Z ２ A and multiple A ２ They may be the same or different from each other.

[0056] In formula (E) and formula (F), * represents a bonding position.

[0057]

[0058] Examples of the first polymerizable chiral agent include photoreactive chiral agents described in paragraphs 0044 to 0047 of JP-A-2001-159709, optically active compounds described in paragraphs 0019 to 0043 of JP-A-2002-179669, optically active compounds described in paragraphs 0020 to 0044 of JP-A-2002-179633, optically active compounds described in paragraphs 0016 to 0040 of JP-A-2002-179670, optically active compounds described in paragraphs 0017 to 0050 of JP-A-2002-179668, and optically active compounds described in paragraphs 0018 to 0020 of JP-A-2002-180051. 44, optically active compounds described in paragraphs 0016 to 0055 of JP-A No. 2002-338575, optically active isosorbide derivatives described in paragraphs 0016 to 0055 of JP-A No. 2002-338575, photoreactive optically active compounds described in paragraphs 0023 to 0032 of JP-A No. 2002-080478, photoreactive chiral agents described in paragraphs 0019 to 0029 of JP-A No. 2002-080851, optically active compounds described in paragraphs 0022 to 0049 of JP-A No. 2002-179681, optically active compounds described in paragraphs 0015 to 0044 of JP-A No. 2002-302487, and paragraphs optically active polyesters described in paragraphs 0015 to 0050 of JP-A No. 2003-055315, binaphthol derivatives described in paragraphs 0019 to 0041 of JP-A No. 2003-073381, optically active fulgide compounds described in paragraphs 0008 to 0043 of JP-A No. 2003-073381, optically active isosorbide derivatives described in paragraphs 0015 to 0057 of JP-A No. 2003-306490, optically active isosorbide derivatives described in paragraphs 0015 to 0041 of JP-A No. 2003-306491, optically active isosorbide derivatives described in paragraphs 0015 to 0049 of JP-A No. 2003-313187 Examples of the optically active compound include a compound having a polymerizable group, an optically active conductor, an optically active isomannide derivative described in paragraphs

[0015] to

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

[0015] to

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

[0015] to

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

[0012] to

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

[0020] to

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

[0059] (Second Polymerizable Chiral Agent) The composition layer of step 1 contains a second polymerizable chiral agent. The second polymerizable chiral agent is a chiral agent that induces a helical twist in the opposite direction to that of the first polymerizable chiral agent described above (i.e., the second polymerizable chiral agent is a chiral agent having a rotational ability in the opposite direction to that of the first polymerizable chiral agent described above). For example, if the helical twist induced by the first polymerizable chiral agent is right-handed, the helical twist induced by the second polymerizable chiral agent will be left-handed. The second polymerizable chiral agent is not particularly limited as long as it has a polymerizable group and has a rotational ability in the opposite direction to that of the first polymerizable chiral agent, but is preferably a chiral agent whose helical twisting power does not change upon irradiation with light. The type of polymerizable group possessed by the second polymerizable chiral agent may be the same as that of the second polymerizable chiral agent. The number of polymerizable groups that the second polymerizable chiral agent has is not particularly limited, but is, for example, preferably 1 to 6, more preferably 2 to 4, and even more preferably 2.

[0060] The second polymerizable chiral agent may be liquid crystalline or non-liquid crystalline. The second polymerizable chiral agent generally contains an asymmetric carbon atom. The second polymerizable chiral agent may be an axially asymmetric compound or a planar asymmetric compound that does not contain an asymmetric carbon atom. A known chiral agent can be used as the second polymerizable chiral agent.

[0061] The second polymerizable chiral agent is preferably a compound represented by formula (CB): ３ -sp ３ - (A ３ -Z ３ ) ｐ -L ２ -(Z ４ -A ４ ) ｑ -sp ４ -P ４ In formula (CB), L ２ is L in formula (CA). １ In formula (CB), A has the same meaning as the above, and preferred embodiments are also the same. ３ and A ４ is A in formula (CA) １ In formula (CB), sp ３and sp ４ is the sp in formula (CA). １ In formula (CB), P ３ and P ４ represents P in formula (CA). １ The same definition and preferred embodiments are also the same. ３ and P ４ At least one of the groups represents a polymerizable group, and it is preferable that both of the groups represent polymerizable groups. Examples of the polymerizable group include the polymerizable groups described above. In formula (CB), p and q have the same meaning as m in formula (CA), and preferred embodiments are also the same.

[0062] In formula (CB), Z ３ and Z ４ represents Z in formula (CA). １ It is synonymous with Z. ３ and Z ４ Examples of the divalent linking group represented by the formula: ２ -, -COO-, -CO-S-, -O-CO-O-, -CO-NR-, -SCHR-, -SO-CHR-, -SO ２ -CHR-, -CF ２ O-, -CF ２ S-, -OCHRCHRO-, -SCHRCHRS-, -SO-CHRCHR-SO-, -SO ２ -CHRCHR-SO ２ -, -COO-CHRCHR-, -OCO-CHRCHR-, -COO-CHR-, or -OCO-CHR- is preferred, and -O-, -CO-, -COO-, or -CO-NR- is more preferred. R represents a hydrogen atom, a cyano group, or an alkyl group having 1 to 10 carbon atoms. When multiple Rs are present in the formula, the multiple Rs may be the same or different from one another. In the formula, Z ３ If there are multiple Z ３ may be the same or different. ４ If there are multiple Z ４ They may be the same or different from each other.

[0063] The molar absorption coefficients of the first polymerizable chiral agent and the second polymerizable chiral agent are not particularly limited, but the molar absorption coefficient at the wavelength of light irradiated in Step 3 described below (e.g., 365 nm) is preferably 100 to 100,000 L / (mol cm), and more preferably 500 to 50,000 L / (mol cm).

[0064] The helical pitch of the liquid crystal compound in the cholesteric liquid crystal layer is largely dependent on the type and concentration of the first polymerizable chiral agent and the second polymerizable chiral agent, and the alignment state of the liquid crystal compound can be controlled by adjusting these factors. In step 1, the total content of the first polymerizable chiral agent and the second polymerizable chiral agent in the composition layer is not particularly limited, but in terms of ease of control of the alignment state of the liquid crystal compound, it is preferably more than 5.0% by mass, more preferably 5.5% by mass or more, and even more preferably 6.0% by mass or more, relative to the total mass of the liquid crystal compound. The upper limit is not particularly limited, but is preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less.

[0065] The content of the first polymerizable chiral agent is not particularly limited, but from the viewpoint of facilitating control of the alignment state of the liquid crystal compound, it is preferably 5 to 95 mass %, more preferably 10 to 90 mass %, and even more preferably 15 to 50 mass %, relative to the total content of the first polymerizable chiral agent and the second polymerizable chiral agent.

[0066] The content of the first polymerizable chiral agent in the composition layer is not particularly limited, but 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 mass of the composition layer. The upper limit is not particularly limited, but is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3.5% by mass or less. The content of the second polymerizable chiral agent in the composition layer is not particularly limited, but 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, relative to the total mass of the composition layer. The upper limit is not particularly limited, but is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 6.0% by mass or less.

[0067] <Liquid Crystal Compound> The composition layer of step 1 contains a liquid crystal compound having a polymerizable group (polymerizable liquid crystal compound). The polymerizable liquid crystal compound may be a rod-shaped liquid crystal compound or a discotic liquid crystal compound, but is preferably a rod-shaped liquid crystal compound. Examples of rod-shaped liquid crystal compounds include rod-shaped nematic liquid crystal compounds. Examples of rod-shaped nematic liquid crystal compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoates, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes, and alkenylcyclohexylbenzonitriles. Not only low-molecular-weight liquid crystal compounds but also polymer-molecular-weight liquid crystal compounds can be used.

[0068] A polymerizable liquid crystal compound can be obtained by introducing a polymerizable group into a liquid crystal compound. The type of polymerizable group possessed by the polymerizable liquid crystal compound is not particularly limited, and a functional group capable of an addition polymerization reaction is preferred, a polymerizable ethylenically unsaturated group or a ring-polymerizable group is more preferred, and examples thereof include unsaturated polymerizable groups (e.g., (meth)acryloyl group, vinyl group, styryl group, allyl group, etc.), an epoxy group, and an aziridinyl group. An unsaturated polymerizable group is preferred, and an ethylenically unsaturated polymerizable group is more preferred. The polymerizable group can be introduced into the molecule of the liquid crystal compound by various methods. The number of polymerizable groups possessed by the polymerizable liquid crystal compound is preferably 1 to 6, more preferably 1 to 3, per molecule.

[0069] As the polymerizable liquid crystal compound, there are mentioned Makromol. Chem. , Vol. 190, p. 2255 (1989), Advanced Materials Vol. 5, p. 107 (1993), U.S. Pat. Nos. 4,683,327, 5,622,648, U.S. Pat. No. 5,770,107, WO 95 / 022586, WO 95 / 024455, WO 97 / 00600, WO 98 / 23580, WO 98 / 52905, JP-A-1-272551, JP-A-6-016616, JP-A-7-110469, JP-A-11-080081, and JP-A-2001-328973 include compounds described in the like. In the composition, two or more types of polymerizable liquid crystal compounds may be used in combination.

[0070] The content of the polymerizable liquid crystal compound in the composition layer is not particularly limited, but is preferably 60% by mass or more, more preferably 70% by mass or more, relative to the total mass of the composition layer, from the viewpoint of facilitating control of the alignment state of the liquid crystal compound. The upper limit is not particularly limited, but is preferably 99% by mass or less, more preferably 97% by mass or less, even more preferably 95% by mass or less, and particularly preferably 90% by mass or less.

[0071] <Other Components> The composition layer may contain components other than the first polymerizable chiral agent, the second polymerizable chiral agent, and the polymerizable liquid crystal compound. For example, the composition layer may contain a polymerization initiator. When the composition layer contains a polymerization initiator, the polymerization of the liquid crystal compound having a polymerizable group proceeds more efficiently. Examples of the polymerization initiator include known polymerization initiators, such as photopolymerization initiators and thermal polymerization initiators, with photopolymerization initiators being preferred. The content of the polymerization initiator in the composition layer is not particularly limited, but is preferably 0.01 to 20% by mass, and more preferably 0.5 to 10% by mass, relative to the total mass of the composition layer.

[0072] The composition layer may contain a surfactant. Examples of surfactants include conventionally known compounds, such as hydrocarbon surfactants, fluorine-based surfactants, and silicone-based surfactants. From the viewpoint of improving environmental compatibility, it is preferable that the surfactant does not contain fluorine atoms. The surfactant is preferably a hydrocarbon-based surfactant or a silicone-based surfactant. Examples of fluorine-based surfactants include the compounds described in paragraphs

[0028] to

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

[0069] to

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

[0073] The composition layer may contain an additive (alignment control agent) that promotes horizontal or vertical alignment of the liquid crystal compound in order to achieve horizontal or vertical alignment. Examples of alignment control agents include fluorine (meth)acrylate polymers described in paragraphs

[0018] to

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

[0031] to

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

[0074] The content of the alignment control agent in the composition layer is not particularly limited, but is preferably 0.01 to 10% by mass, more preferably 0.01 to 5% by mass, and particularly preferably 0.02 to 1% by mass, based on the total mass of the liquid crystal compound.

[0075] The composition layer may contain other components in addition to those described above, such as a polymerizable monomer, an adhesion improver, a crosslinking agent, a polymerization inhibitor, an antioxidant, an ultraviolet absorber, a light stabilizer, a colorant, and metal oxide fine particles.

[0076] <Substrate> When forming a composition layer, it is preferable to form the composition layer on a substrate. The substrate is a plate that supports the composition layer. The substrate is preferably a transparent substrate. Note that a transparent substrate refers to a substrate having a visible light transmittance of 60% or more, preferably 80% or more, and more preferably 90% or more.

[0077] The retardation value (Rth(550)) in the thickness direction of the substrate at a wavelength of 550 nm is not particularly limited, but is preferably −110 to 110 nm, more preferably −80 to 80 nm. The in-plane retardation value (Re(550)) of the substrate 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.

[0078] The material for forming the substrate is preferably a polymer excellent in optical performance transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, etc. Examples of polymer films that can be used as the substrate include cellulose acylate films (e.g., cellulose triacetate film (refractive index 1.48), cellulose diacetate film, cellulose acetate butyrate film, cellulose acetate propionate film), polyolefin films such as polyethylene and polypropylene, polyester films such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone films, polyacrylic films such as polymethyl methacrylate, polyurethane films, polycarbonate films, polysulfone films, polyether films, polymethylpentene films, polyether ketone films, (meth)acrylonitrile films, and films of polymers having an alicyclic structure (norbornene-based resins (Arton: trade name, manufactured by JSR Corporation, amorphous polyolefins (Zeonex: trade name, manufactured by Nippon Zeon Co., Ltd.))). Among these, triacetyl cellulose, polyethylene terephthalate, or a polymer having an alicyclic structure is preferred as the material for the polymer film, and triacetyl cellulose is more preferred.

[0079] The substrate may contain various additives (for example, an optical anisotropy adjusting agent, a wavelength dispersion adjusting agent, fine particles, a plasticizer, an ultraviolet inhibitor, an anti-degradation agent, a release agent, and the like).

[0080] The thickness of the substrate is not particularly limited, but is preferably 10 to 200 μm, more preferably 10 to 100 μm, and even more preferably 20 to 90 μm. The substrate may also be composed of a laminate of multiple sheets. To improve adhesion to a layer disposed thereon, the surface of the substrate may be subjected to a surface treatment (e.g., glow discharge treatment, corona discharge treatment, ultraviolet (UV) treatment, flame treatment, etc.). An adhesive layer (undercoat layer) may also be provided on the substrate. A polymer layer containing 5 to 40% by mass of inorganic particles with an average particle size of approximately 10 to 100 nm in solid content may be disposed on one side of the substrate to impart slipperiness during the transport process or to prevent sticking of the back and front surfaces after winding.

[0081] The substrate may be a so-called temporary support, that is, the substrate may be peeled off from the cholesteric liquid crystal layer after carrying out the manufacturing method of the present invention.

[0082] Alternatively, the surface of the substrate may be directly subjected to rubbing treatment. In other words, a rubbed substrate may be used. The direction of the rubbing treatment is not particularly limited, and an optimal direction may be appropriately selected depending on the desired direction of alignment of the liquid crystal compound. The rubbing treatment may be a treatment method that is widely used as a liquid crystal alignment treatment step for LCDs (liquid crystal displays). In other words, a method of obtaining alignment by rubbing the surface of the substrate in a certain direction using paper, gauze, felt, rubber, nylon fiber, polyester fiber, or the like may be used.

[0083] An alignment film may be disposed on the substrate. The alignment film can be formed by means of rubbing an organic compound (preferably a polymer), oblique deposition of an inorganic compound, formation of a layer with microgrooves, or deposition of an organic compound (e.g., ω-tricosanoic acid, dioctadecylmethylammonium chloride, and methyl stearate) by the Langmuir-Blodgett method (LB film). Furthermore, alignment films that exhibit alignment function upon application of an electric field, a magnetic field, or light irradiation (preferably polarized light) are also known. The alignment film is preferably formed by rubbing a polymer.

[0084] Examples of polymers contained in the alignment film include methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohol and modified polyvinyl alcohol, poly(N-methylolacrylamide), polyesters, polyimides, vinyl acetate copolymers, carboxymethyl cellulose, and polycarbonates, as described in paragraph 0022 of JP-A-8-338913. Silane coupling agents can also be used as the polymer. Among these, water-soluble polymers (e.g., poly(N-methylolacrylamide), carboxymethyl cellulose, gelatin, polyvinyl alcohol, and modified polyvinyl alcohol) are preferred, with gelatin, polyvinyl alcohol, or modified polyvinyl alcohol being more preferred, and polyvinyl alcohol or modified polyvinyl alcohol being even more preferred.

[0085] As described above, the alignment film can be formed by applying a solution containing the above-mentioned polymer, which is an alignment film forming material, and any additives (e.g., a crosslinking agent) onto a substrate, followed by heating and drying (crosslinking) and rubbing treatment.

[0086] <Procedure of Step 1> In Step 1, a composition layer containing the above-mentioned components is formed, but the procedure is not particularly limited. For example, a method of applying a composition containing the above-mentioned first polymerizable chiral agent, second polymerizable chiral agent, and polymerizable liquid crystal compound onto a substrate and optionally performing a drying treatment (hereinafter also simply referred to as "application method"), and a method of separately forming a composition layer and transferring it onto a substrate are included. Among these, the application method is preferred from the viewpoint of productivity. The application method will be described in detail below.

[0087] The composition used in the coating method contains the above-described first polymerizable chiral agent, second polymerizable chiral agent, polymerizable liquid crystal compound, and other components (e.g., polymerization initiator, etc.) that are used as needed. The content of each component in the composition is preferably adjusted to the content of each component in the above-described composition layer.

[0088] When a coating method is used, the composition may contain a solvent. The solvent is preferably one that can dissolve each component of the composition, and examples thereof include methyl ethyl ketone, cyclohexanone (anone), and mixed solvents thereof. When the composition contains a solvent, the content of the solvent in the composition is preferably an amount that makes the solids concentration of the composition 5 to 50 mass %, more preferably an amount that makes 10 to 40 mass %. The composition may use one solvent alone, or two or more solvents. When two or more solvents are used, the total content thereof is preferably within the above range.

[0089] The coating method is not particularly limited, and examples thereof include wire bar coating, extrusion coating, direct gravure coating, reverse gravure coating, and die coating. If necessary, after coating the composition, a treatment for drying the coating film coated on the substrate may be carried out. By carrying out the drying treatment, the solvent can be removed from the coating film.

[0090] The thickness of the coating film is not particularly limited, but is preferably 0.1 to 20 μm, more preferably 0.2 to 15 μm, and even more preferably 0.5 to 10 μm.

[0091] [Step 2] Step 2 is a step of aligning the liquid crystal compound in the composition layer. By performing this step, the liquid crystal compound in the composition layer is aligned in a cholesteric liquid crystal phase. That is, as shown in FIG. 1, step 2 forms a composition layer 12 on a substrate 10 in which the liquid crystal compound LC is aligned in a cholesteric liquid crystal phase. FIG. 1 is a schematic cross-sectional view of the substrate 10 and the composition layer 12. Step 2 is preferably a step of aligning the liquid crystal compound in the composition layer by subjecting the composition layer to a heat treatment. Optimal conditions for the heat treatment are selected depending on the liquid crystal compound used. The heating temperature is often 25 to 250°C, more often 40 to 150°C, and even more often 50 to 130°C. The heating time is often 0.1 to 60 minutes, more often 0.2 to 5 minutes.

[0092] The alignment state of the liquid crystal compound obtained by step 2 varies depending on the helical twisting power and the concentration of the first polymerizable chiral agent and the second polymerizable chiral agent. The absolute value of the weighted average helical twisting power of the chiral agent in the composition layer formed by step 1 is 10.0 μm －１ More than 15.0 μm is preferable. －１ More preferably, 20.0 μm or more －１ The upper limit is not particularly limited, but is preferably 250 μm or more. －１ In most cases, it is less than 200 μm. －１ Preferably less than 100 μm －１ The following is more preferable: When the absolute value of the weighted average helical twisting power of the chiral dopant in the composition layer is within the above range, the liquid crystal compound in the composition can be cholesterically aligned by step 2.

[0093] Here, the weighted average helical twisting power of a chiral agent refers to the sum of the values ​​obtained by dividing the product of the helical twisting power of each chiral agent contained in the composition layer and the concentration (% by mass) of each chiral agent in the composition layer when two or more chiral agents are contained in the composition layer by the total concentration (% by mass) of the chiral agents in the composition layer. For example, when two types of chiral agents (chiral agent X and chiral agent Y) are used in combination, the weighted average helical twisting power is expressed by the following formula (B): Formula (B) Weighted average helical twisting power (μm －１ ) = (helix-inducing power of chiral agent X (μm－１ ) × concentration of chiral dopant X in the composition layer (% by mass) + helical twisting power of chiral dopant Y (μm －１ ) × concentration of chiral dopant Y in the composition layer (mass %)) / (concentration of chiral dopant X in the composition layer (mass %) + concentration of chiral dopant Y in the composition layer (mass %)) However, in the above formula (B), when the helical direction of the chiral dopant is right-handed, the helical twisting power is a positive value. On the other hand, when the helical direction of the chiral dopant is left-handed, the helical twisting power is a negative value. That is, for example, when the helical twisting power is 10 μm －１ In the case of the chiral agent, when the helical direction of the helix induced by the chiral agent is right-handed, the helix-inducing force is 10 μm －１ On the other hand, when the helical direction of the helix induced by the chiral agent is left-handed, the helical induction force is −10 μm －１ It is expressed as:

[0094] [Step 3] In step 3, after step 2, the composition layer is irradiated with light of a wavelength capable of changing the helical twisting power of the first polymerizable chiral agent under conditions of an oxygen concentration of 1% by volume or more. The mechanism of this step is explained below with reference to the drawings. As shown in FIG. 1 , in step 3, light irradiation is performed from the direction opposite the composition layer 12 side of the substrate 10 (the direction of the white arrow in FIG. 1 ) under conditions of an oxygen concentration of 1% by volume or more. Note that while light irradiation is performed from the substrate 10 side in FIG. 1 , it may also be performed from the composition layer 12 side. In this case, when comparing the lower region 12A on the substrate 10 side of the composition layer 12 with the upper region 12B on the opposite side from the substrate 10 side, the surface of the upper region 12B is closer to the air, so the oxygen concentration in the upper region 12B is higher and the oxygen concentration in the lower region 12A is lower. Therefore, when the composition layer 12 is irradiated with light, polymerization of the liquid crystal compound in the lower region 12A is more likely to proceed, and the alignment state of the liquid crystal compound is fixed. The first polymerizable chiral agent is also present in the lower region 12A, and is thus photosensitive, resulting in a change in the helical twisting force. However, because the alignment state of the liquid crystal compound is fixed in the lower region 12A, the alignment state of the liquid crystal compound does not change even when a heat treatment involving light irradiation in step 3 (described later) or a heat treatment in step 5 (described later) of the composition layer irradiated with light in step 3 is performed. Furthermore, because the oxygen concentration in the upper region 12B is high, even when light is irradiated, the polymerization of the liquid crystal compound is inhibited by oxygen and polymerization does not proceed easily. Furthermore, because the first polymerizable chiral agent is also present in the upper region 12B, the first polymerizable chiral agent is photosensitive, resulting in a change in the helical twisting force. Therefore, when a heat treatment involving light irradiation in step 3 (described later) or a heat treatment in step 5 (described later) of the composition layer irradiated with light in step 3 is performed, the alignment state of the liquid crystal compound changes in accordance with the changed helical twisting force. In other words, the light irradiation in step 3 facilitates the fixation of the alignment state of the liquid crystal compound in the region (lower region) of the composition layer facing the substrate. Furthermore, in the region of the composition layer opposite the substrate side (upper region), the alignment state of the liquid crystal compound is less likely to be fixed, and the helical twisting force changes depending on the photoexposed first polymerizable chiral agent.

[0095] The light irradiation in step 3 is carried out under conditions of an oxygen concentration of 1% by volume or more. In particular, the oxygen concentration is preferably 2% by volume or more, more preferably 5% by volume or more, in order to easily form regions in which the liquid crystal compound has a different orientation state in the cholesteric liquid crystal layer. The upper limit is not particularly limited, but may be 100% by volume.

[0096] The light irradiation time in step 3 is preferably 50 seconds or less, more preferably 30 seconds or less, and even more preferably 10 seconds or less. There is no particular lower limit, but from the viewpoint of curing the liquid crystal compound, the time is preferably 0.1 seconds or more, and more preferably 0.2 seconds or more. The irradiation dose of light irradiation in step 3 is 300 mJ / cm. ２ Preferably, 250 mJ / cm or less ２ More preferably, 200 mJ / cm or less ２ The lower limit is not particularly limited, but from the viewpoint of curing of the liquid crystal compound, it is more preferably 1 mJ / cm. ２ More than 5 mJ / cm is preferable. ２ The above is more preferable. When step 5 is carried out after the light irradiation in step 3, the light irradiation in step 3 is preferably carried out at 15 to 70°C (preferably 25 to 50°C). On the other hand, when a heat treatment is also carried out during the light irradiation in step 3, the temperature is preferably a temperature at which the unfixed liquid crystal compound in the composition layer is aligned, and more specifically, the temperature is often 40 to 250°C, more often 50 to 150°C, even more often higher than 50°C and 150°C or lower, and particularly often 60 to 130°C. When a heat treatment is also carried out during the light irradiation in step 3, the heating time is often 0.01 to 60 minutes, more often 0.03 to 5 minutes.

[0097] The light used for the photoirradiation may be any light to which the first polymerizable chiral agent is photosensitive. In other words, the light used for the photoirradiation is not particularly limited as long as it is actinic ray or radiation that changes the helical twisting power of the first polymerizable chiral agent, and examples thereof include the bright line spectrum of a mercury lamp, far ultraviolet light represented by an excimer laser, extreme ultraviolet light, X-rays, ultraviolet light, and electron beams. Among these, ultraviolet light is preferred.

[0098] Heat treatment may also be carried out during the light irradiation in step 3. The heat treatment accompanying the light irradiation in step 3 will be described later together with step 5.

[0099] [Step 5] Step 5 is a step of subjecting the composition layer to a heat treatment between steps 3 and 4. Note that if a heat treatment is performed during the light irradiation in step 3, step 5 may not be performed. The manufacturing method of the present invention preferably includes step 5, since it facilitates the formation of a predetermined cholesteric liquid crystal layer. Step 5 is preferably a step of subjecting the composition layer to a heat treatment at a temperature higher than that during the light irradiation in step 3, since it facilitates the formation of a predetermined cholesteric liquid crystal layer. By performing step 5, the alignment state of the liquid crystal compound changes in the region in the composition layer subjected to the light irradiation in step 3, where the helical twisting force of the first polymerizable chiral agent has changed. More specifically, step 5 is a step of subjecting the composition layer after the light irradiation in step 3 to a heat treatment (preferably at a temperature higher than that during the light irradiation in step 3) to align the liquid crystal compound in the composition layer that has not been fixed by the light irradiation in step 3. The mechanism of this step is described below with reference to the drawings.

[0100] As described above, when the composition layer 12 shown in Fig. 1 is irradiated with light in step 3, the orientation state of the liquid crystal compound is fixed in the lower region 12A, whereas polymerization of the liquid crystal compound is difficult to proceed in the upper region 12B, and the orientation state of the liquid crystal compound is not fixed. Furthermore, in the upper region 12B, the weighted average helical twisting power of the first polymerizable chiral agent and the second polymerizable chiral agent changes due to a change in the helical twisting power of the first polymerizable chiral agent. When this change in the helical twisting power of the first polymerizable chiral agent occurs, the force twisting the liquid crystal compound in the upper region 12B changes compared to the state before the light irradiation in step 3.

[0101] The change in the weighted average helical twisting power before light irradiation in step 3 will be described in detail below. In the following description, it is assumed that the composition layer 12 contains a first polymerizable chiral agent that induces a left-handed helical twist and whose helical twisting power decreases upon light irradiation, and a second polymerizable chiral agent that induces a right-handed helical twist and whose helical twisting power does not change upon light irradiation, and that the "helical twisting power of the first polymerizable chiral agent (μm－１ ) × concentration (mass %) of first polymerizable chiral agent < absolute value of "helix-inducing power (μm －１ ) × concentration (mass %) of the second polymerizable chiral agent. －１ ) × concentration (mass%) and light irradiation dose (mJ / cm ２ ) of the first polymerizable chiral agent and the second polymerizable chiral agent. －１ ) and light irradiation dose (mJ / cm ２ ) is plotted as a function of the temperature.

[0102] In Figures 2 and 3, the vertical axis represents the helical twisting power of the chiral agent (μm －１ ) × concentration (mass %) of chiral agent, and the further this value is from zero, the stronger the helical twisting power. First, the relationship between the first polymerizable chiral agent and the second polymerizable chiral agent in the composition layer in step 2 (i.e., the composition layer before light irradiation in step 3) corresponds to the point when the light irradiation amount is 0. As shown in Figures 2 and 3, the weighted average helical twisting power is greater than 0 when the light irradiation amount is 0. Therefore, in composition layer 12 in which the liquid crystal compound LC formed in step 2 is aligned in a cholesteric liquid crystal state, the helical structure of the cholesteric liquid crystal phase is a right-handed helical structure derived from the second polymerizable chiral agent.

[0103] When light irradiation is performed in the upper region 12B in this state, and the helical twisting power of the first polymerizable chiral agent decreases with the amount of light irradiation as shown in Figures 2 and 3, the weighted average helical twisting power of the chiral agent in the upper region 12B in Figure 1 increases, resulting in a stronger right-handed helical twisting power. In other words, the helical twisting power of the liquid crystal compound increases with the irradiation dose, and the helical twisting power in the direction (+) of the helical twist induced by the second polymerizable chiral agent increases. Therefore, when the composition layer 12 after light irradiation in step 3, in which such a change in weighted average helical twisting power has occurred, is subjected to the heat treatment in step 5 to promote reorientation of the liquid crystal compound, as shown in Figure 4, in the upper region 12B, the liquid crystal compound LC is more strongly twisted and aligned 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 liquid crystal compound progresses during light irradiation in step 3, fixing the alignment state of the liquid crystal compound, and therefore reorientation of the liquid crystal compound does not proceed. As described above, by carrying out step 5, a plurality of regions with different helical pitches are formed along the thickness direction of the composition layer.

[0104] 2 to 4, the embodiment using a chiral agent whose helical twisting power decreases upon irradiation with light has been described, but the present invention is not limited to this embodiment. For example, the first polymerizable chiral agent may be a chiral agent whose helical twisting power increases upon irradiation with light. In this case, for example, as shown in FIG. 5, the weighted average helical twisting power of the cholesteric liquid crystal layer decreases upon irradiation with light in step 3.

[0105] The heat treatment in step 5 is preferably carried out at a temperature higher than that during light irradiation in step 3. The difference between the temperature during the heat treatment in step 5 and the temperature during light irradiation in step 3 is preferably 5°C or more, more preferably 10 to 110°C, and even more preferably 20 to 110°C.

[0106] The temperature of the heat treatment in step 5 is preferably higher than the temperature during light irradiation in step 3 and is a temperature at which the unfixed liquid crystal compound in the composition layer is aligned, and more specifically, is often 40 to 250° C., more often 50 to 150° C., even more often higher than 50° C. and not higher than 150° C., and particularly often 60 to 130° C. The heating time in step 5 is often 0.01 to 60 minutes, more often 0.03 to 5 minutes.

[0107] The absolute value of the difference between the weighted average helical twisting power of the chiral agent in the composition layer after the light irradiation in step 3 and the weighted average helical twisting power before the light irradiation in step 3 was 0.05 μm. －１ More than this is preferred, and 0.05 to 20.0 μm －１ More preferably, 0.1 to 15.0 μm －１ is more preferably 1.0 to 15.0 μm －１ is particularly preferred, and 5.0 to 15.0 μm －１ is most preferred.

[0108] Furthermore, instead of step 5, a heat treatment may be carried out when the light irradiation in step 3 is carried out. By carrying out a heat treatment during the light irradiation in step 3, the same effect as in step 5 can be obtained. When the heat treatment is carried out during the light irradiation in step 3, the heat treatment may be carried out before the light irradiation or during the light irradiation. When the heat treatment is carried out during the light irradiation in step 3, the heating temperature and heating time are as described above.

[0109] [Step 4] Step 4 is a step in which the composition layer is cured after the heat treatment associated with the light irradiation in Step 3 or the heat treatment in Step 5 (i.e., after the liquid crystal compound has been reoriented) to fix the alignment state of the liquid crystal compound and form a cholesteric liquid crystal layer having a plurality of regions with different helical pitches along the thickness direction. Note that the length of the helical pitch in each of the formed regions is often constant. In other words, by carrying out this step, it is possible to form a cholesteric liquid crystal phase layer formed by fixing a cholesteric liquid crystal phase, which has a plurality of regions with different helical pitches of the cholesteric liquid crystal phase along the thickness direction, and in which the helical pitch in each region is constant.

[0110] The curing method is not particularly limited, and examples thereof include photocuring and heat curing. Of these, photoirradiation is preferred, and ultraviolet irradiation is more preferred. For ultraviolet irradiation, a light source such as an ultraviolet lamp is used. A wavelength cut filter may also be used during ultraviolet irradiation. The irradiation dose of light (e.g., ultraviolet) is not particularly limited, but is generally 100 to 800 mJ / cm. ２ The atmosphere during light irradiation is not particularly limited, and light irradiation may be carried out in air or in an inert atmosphere. In particular, light irradiation is preferably carried out in an oxygen concentration of less than 1% by volume.

[0111] When a photocuring treatment is carried out as the curing treatment in step 4, the temperature conditions during photocuring are not particularly limited, and may be any temperature at which the alignment state of the liquid crystal compound is maintained after the heat treatment accompanying light irradiation in step 3 or after the heat treatment in step 5. The difference between the temperature of the heat treatment accompanying light irradiation in step 3 or the heat treatment in step 5 and the temperature during the photocuring treatment in step 4 is preferably within 100°C, more preferably within 80°C. It is preferable that the temperature of the heat treatment accompanying light irradiation in step 3 or the heat treatment in step 5 is the same as the temperature during the photocuring treatment in step 4, or that the temperature during the photocuring treatment in step 4 is lower.

[0112] In the cholesteric liquid crystal layer obtained by carrying out the curing treatment, the alignment state of the liquid crystal compound is fixed. In this specification, the "fixed" state refers to a state in which the alignment of the liquid crystal compound is maintained, which is the most typical and preferred embodiment. However, it is not limited thereto. Specifically, it is more preferable that the layer has no fluidity and can stably maintain the fixed alignment state without causing any change in the alignment state due to an external field or external force, usually within a temperature range of 0 to 50°C, or under more severe conditions, within a temperature range of -30 to 70°C. In the cholesteric liquid crystal layer, it is not necessary for the composition in the layer to finally exhibit liquid crystallinity.

[0113] The thickness of the cholesteric liquid crystal layer is not particularly limited, but is preferably 0.05 to 10 μm, more preferably 0.1 to 8.0 μm, and even more preferably 0.2 to 6.0 μm. The thickness of the cholesteric liquid crystal is particularly preferably 1.8 μm or less, and most preferably 1.2 μm or less.

[0114] In the cholesteric liquid crystal layer formed by the above method, in which a cholesteric liquid crystal phase is fixed, and in which the cholesteric liquid crystal layer has a plurality of regions with different helical pitches of the cholesteric liquid crystal phase along the thickness direction, the selective reflection central wavelength derived from the cholesteric liquid crystal phase of each region is different. For example, the cholesteric liquid crystal layer may be a cholesteric liquid crystal layer having, along the thickness direction, a region in which a cholesteric liquid crystal phase that reflects blue light is fixed and a region in which a cholesteric liquid crystal phase that reflects green light is fixed, or a cholesteric liquid crystal layer having, along the thickness direction, a region in which a cholesteric liquid crystal phase that reflects green light is fixed and a region in which a cholesteric liquid crystal phase that reflects red light is fixed. In this specification, the selective reflection central wavelength refers to the wavelength at which the minimum value of transmittance of the target object (member) is T min (%), the half-value transmittance is expressed by the following formula: T １／２ The half-value transmittance is the average value of two wavelengths (%). １／２ =100-(100-T min ) ÷ 2 Furthermore, among visible light, light in the wavelength range of 420 nm or more and less than 500 nm is blue light (B light), light in the wavelength range of 500 nm or more and less than 600 nm is green light (G light), and light in the wavelength range of 600 nm or more and less than 700 nm is red light (R light).

[0115] 4 illustrates a cholesteric liquid crystal layer having two regions with different helical pitches, but the present invention is not limited to this embodiment, and the cholesteric liquid crystal layer may have three or more regions with different helical pitches. Examples of such a cholesteric liquid crystal layer include a cholesteric liquid crystal layer having, along the thickness direction, a region in which a cholesteric liquid crystal phase that reflects blue light is fixed, a region in which a cholesteric liquid crystal phase that reflects green light is fixed, and a region in which a cholesteric liquid crystal phase that reflects red light is fixed.

[0116] [Cholesteric Liquid Crystal Layer] The cholesteric liquid crystal layer of the present invention is a cholesteric liquid crystal layer formed by fixing a cholesteric liquid crystal phase, and has a plurality of regions with different helical pitches in the thickness direction, and is formed using a composition containing a liquid crystal compound having a polymerizable group (polymerizable liquid crystal compound), a first polymerizable chiral agent (first polymerizable chiral agent) whose helical twisting force changes upon light irradiation, and a second polymerizable chiral agent (second polymerizable chiral agent) having a rotational ability in the opposite direction to that of the first polymerizable chiral agent.

[0117] The cholesteric liquid crystal layer of the present invention is a cholesteric liquid crystal layer formed by fixing a cholesteric liquid crystal phase, and has a plurality of regions along the thickness direction, each region having a different helical pitch of the cholesteric liquid crystal phase, and the selective reflection center wavelength derived from the cholesteric liquid crystal phase is different in each region. For example, the cholesteric liquid crystal layer may be a cholesteric liquid crystal layer having, along the thickness direction, a region where a cholesteric liquid crystal phase that reflects blue light is fixed and a region where a cholesteric liquid crystal phase that reflects green light is fixed, or a cholesteric liquid crystal layer having, along the thickness direction, a region where a cholesteric liquid crystal phase that reflects green light is fixed and a region where a cholesteric liquid crystal phase that reflects red light is fixed.

[0118] The thickness of the cholesteric liquid crystal layer is not particularly limited, but is preferably 0.05 to 10 μm, more preferably 0.1 to 8.0 μm, and even more preferably 0.2 to 6.0 μm. The thickness of the cholesteric liquid crystal is particularly preferably 1.8 μm or less, and most preferably 1.2 μm or less.

[0119] The composition may be any of the various components forming the composition layer in step 1 of the manufacturing method of the present invention described above. The content of the first polymerizable chiral agent in the composition is not particularly limited, but 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 not particularly limited, but is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3.5% by mass or less. The content of the second polymerizable chiral agent in the composition is not particularly limited, but 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, relative to the total solid content of the composition. The upper limit is not particularly limited, but is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 6.0% by mass or less. The content of the polymerizable liquid crystal compound in the composition is not particularly limited, but 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 is preferably 99% by mass or less, more preferably 97% by mass or less, even more preferably 95% by mass or less, and particularly preferably 90% by mass or less.

[0120] The total content of the first polymerizable chiral agent and the second polymerizable chiral agent in the composition can be appropriately set to an amount that can provide the desired selective reflection center wavelength. Specific examples of the total content of the first polymerizable chiral agent and the second polymerizable chiral agent in the composition are preferably more than 5.0% by mass, more preferably 5.5% by mass or more, and even more preferably 6.0% by mass or more, relative to the total mass of the liquid crystal compound. There is no particular upper limit, but it is preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less. The content of the first polymerizable chiral agent can be appropriately set to an amount that can provide the desired selective reflection center wavelength, and is, for example, preferably 5 to 95% by mass, more preferably 10 to 90% by mass, and even more preferably 15 to 50% by mass, relative to the total content of the first polymerizable chiral agent and the second polymerizable chiral agent.

[0121] The composition may contain components other than the polymerizable liquid crystal compound, the first polymerizable chiral agent, and the second polymerizable chiral agent. Examples of such components include a polymerization initiator, a surfactant, and an alignment control agent. Specific examples of the polymerization initiator, surfactant, and alignment control agent include the same polymerization initiator, surfactant, and alignment control agent that may be contained in the composition layer in step 1 of the manufacturing method of the present invention described above. The content of the polymerization initiator in the composition is not particularly limited, but is preferably 0.01 to 20% by mass, and more preferably 0.5 to 10% by mass, based on the total solid content of the composition. The content of the alignment control agent in the composition is not particularly limited, but is preferably 0.01 to 10% by mass, more preferably 0.01 to 5% by mass, and particularly preferably 0.02 to 1% by mass, based on the total mass of the liquid crystal compound.

[0122] The composition may contain other components in addition to those described above, such as a polymerizable monomer, a crosslinking agent, a polymerization inhibitor, an antioxidant, an ultraviolet absorber, a light stabilizer, a colorant, and metal oxide fine particles.

[0123] The cholesteric liquid crystal layer can be formed by the manufacturing method of the present invention described above.

[0124] [Reflective Film] The reflective film of the present invention has a cholesteric liquid crystal layer. The cholesteric liquid crystal layer has been described above. Hereinafter, an example of an embodiment of the reflective film of the present invention will be described with reference to the drawings. When the reflective film is incorporated into a windshield glass and used as a combiner for a head-up display, it is preferable that the projected image light is p-polarized, i.e., linearly polarized light, in order to suppress reflection on the surface of the windshield glass. For this reason, it is desirable that the reflective film reflects linearly polarized light. Therefore, an embodiment of a reflective film that reflects linearly polarized light will be described in detail below. The reflective film may also have a transparent support that supports the cholesteric liquid crystal layer.

[0125] [First embodiment of reflective film] Fig. 6 is a schematic diagram showing an example of the reflective film of the present invention. The reflective film 20 shown in Fig. 6 includes, in this order, a transparent support 22, a first retardation layer 24, a cholesteric liquid crystal layer 26, and a second retardation layer 28. Note that in the reflective film 20, the transparent support 22 is an optional component and may not be included.

[0126] <Transparent Support 22> The total light transmittance of the transparent support 22 is preferably 80% or more, more preferably 90% or more. There is no particular upper limit, but it may be less than 100%. The in-plane retardation of the transparent support 22 is preferably 10 nm or less, more preferably 5 nm or less. The absolute value of the retardation Rth in the thickness direction of the transparent support is preferably 40 nm or less, more preferably 30 nm or less. When the in-plane retardation and the retardation in the thickness direction are small, the disturbance of polarization caused by the transparent support is reduced.

[0127] The material constituting the transparent support 22 is not particularly limited, but is preferably a resin, more preferably a cellulose acylate resin or an acrylic resin, still more preferably a cellulose acylate resin, and particularly preferably a triacetyl cellulose resin or a diacetyl cellulose resin.

[0128] The thickness of the transparent support 22 is not particularly limited, but is preferably 5.0 to 1000 μm, more preferably 10 to 250 μm, and even more preferably 15 to 90 μm.

[0129] <First Retardation Layer 24> The first retardation layer 24 changes the state of incident polarized light by imparting a phase difference (optical path difference) to two orthogonal polarized light components. As will be described later, a suitable example of the first retardation layer 24 is a layer (A plate) in which a liquid crystal compound is uniaxially aligned and fixed.

[0130] Examples of the first retardation layer 24 include a stretched polycarbonate film, a stretched norbornene-based polymer film, a transparent film containing and oriented inorganic particles having birefringence such as strontium carbonate, a thin film obtained by obliquely depositing an inorganic dielectric on a support, and a film in which a liquid crystal compound is uniaxially oriented (nematically oriented) and fixed in orientation, etc. Among these, a film in which a liquid crystal compound is uniaxially oriented and fixed in orientation is preferred as the first retardation layer 24.

[0131] The thickness of the first retardation layer 24 is not particularly limited, but is preferably 0.2 to 300 μm, more preferably 0.5 to 150 μm, and still more preferably 1.0 to 80 μm. When the first retardation layer 24 is a layer in which the orientation of a liquid crystal compound is fixed, the thickness of the first retardation layer 24 is not particularly limited, but is preferably 0.2 to 10 μm, more preferably 0.5 to 5.0 μm, and still more preferably 0.7 to 2.0 μm.

[0132] <Cholesteric Liquid Crystal Layer 26> The cholesteric liquid crystal layer 26 has multiple regions along the thickness direction, each with a different helical pitch of the cholesteric liquid crystal phase, and each region has a different selective reflection center wavelength derived from the cholesteric liquid crystal phase. The cholesteric liquid crystal layer 26 can be a cholesteric liquid crystal layer obtained by the manufacturing method of the present invention described above. Examples of the regions, in order from the transparent support 22 side, include a region having a selective reflection center wavelength in the red (R) wavelength range, a region having a selective reflection center wavelength in the green (G) wavelength range, and a region having a selective reflection center wavelength in the blue (B) wavelength range. The cholesteric liquid crystal layer 26 reflects light with a selective reflection center wavelength corresponding to the helical pitch and transmits light in other wavelength ranges. Furthermore, the cholesteric liquid crystal layer 26 exhibits selective reflectivity for either left- or right-handed circularly polarized light at a specific wavelength. The cholesteric liquid crystal layer 26 may be a cholesteric liquid crystal layer formed by the manufacturing method of the present application described in the upper part, or may be a laminate of a cholesteric liquid crystal layer formed by the manufacturing method of the present application described in the upper part and another cholesteric liquid crystal layer. Specifically, the cholesteric liquid crystal layer 26 may be formed by laminating, on the surface of a cholesteric liquid crystal layer having a selective reflection center wavelength in the red (IR) wavelength region, a cholesteric liquid crystal layer having, along the thickness direction, a region having a selective reflection center wavelength in the red (R) wavelength region, a region having a selective reflection center wavelength in the green (G) wavelength region, and a region having a selective reflection center wavelength in the blue (B) wavelength region, by the manufacturing method of the present application described in the upper part.

[0133] <Second Retardation Layer 28> The second retardation layer 28 is a so-called polarization conversion layer. A polarization conversion layer exhibits optical rotation and birefringence for visible light and converts the polarization state of incident light. The second retardation layer 28 is preferably a layer in which a helical orientation structure of a liquid crystal compound is fixed. In particular, the second retardation layer 28 is preferably a layer in which a helical orientation structure of a liquid crystal compound is fixed, and the pitch number x of the helical orientation structure and the film thickness y (unit: μm) of the polarization conversion layer preferably satisfy all of the following relational expressions (a) to (c): 0.1≦x≦1.0 (equation (a)) 0.5≦y≦3.0 (equation (b)) 3000≦(1560×y) / x≦50000 (equation (c)) Note that one pitch of the helical structure of the liquid crystal compound is one turn of the helix of the liquid crystal compound. That is, the pitch number is defined as 1 when the director of the helically aligned liquid crystal compound (the long axis direction in the case of a rod-like liquid crystal) rotates 360°.

[0134] When the second retardation layer 28 has a helical structure of a liquid crystal compound, it exhibits optical rotation and birefringence for visible light, which has a wavelength shorter than the reflection peak wavelength in the infrared region. Therefore, it is possible to control polarization in the visible region. By setting the pitch number x of the helical orientation structure of the second retardation layer 28 and the film thickness y of the second retardation layer 28 within the above-described ranges, it is possible to provide the second retardation layer 28 with a function of optically compensating for visible light or a function of converting linearly polarized light (P-polarized light) incident on the reflective film 20 into circularly polarized light.

[0135] The liquid crystal compound has a helical structure that satisfies the relational expressions (a) to (c), so that the second retardation layer 28 exhibits optical activity and birefringence for visible light. In particular, by setting the pitch P of the helical structure of the second retardation layer 28 to a length that corresponds to the pitch P of the cholesteric liquid crystal layer whose selective reflection center wavelength is in the long-wavelength infrared region, the second retardation layer 28 exhibits high optical activity and birefringence for short-wavelength visible light.

[0136] The pitch number x of the spiral structure of the second retardation layer 28 is more preferably 0.1 to 0.8, and the film thickness y is more preferably 0.6 to 2.6 μm. Also, "(1560×y) / x" is more preferably 5000 to 13000.

[0137] Such a second retardation layer 28 can basically be formed in the same manner as a known cholesteric liquid crystal layer.

[0138] <Function of Reflective Film 20> When light enters the reflective film 20 from the first retardation layer 24 or second retardation layer 28 side, the light is reflected by the cholesteric liquid crystal layer 26.

[0139] In one embodiment of incorporating the reflective film 20 of FIG. 6 into a windshield, the second retardation layer 28 is disposed on the second glass sheet (not shown) facing the vehicle interior, and the first retardation layer 24 is disposed on the first glass sheet (not shown) facing the vehicle exterior. In this case, the second retardation layer 28 converts projected P-polarized light (linearly polarized light) into circularly polarized light reflected by the cholesteric liquid crystal layer 26. In contrast, the first retardation layer 24 provides optical compensation for light incident from outside the windshield. For example, S-polarized light incident from outside the windshield changes its polarization state when passing through the second retardation layer 28, resulting in the inclusion of P-polarized light. Polarized sunglasses filter S-polarized light, so this P-polarized light component passes through the polarized sunglasses. This impairs the ability of polarized sunglasses to filter out glare from reflected light, which is primarily S-polarized light, resulting in a problem of impaired driving. In contrast to this, by providing the first retardation layer 24 and providing optical compensation with the first retardation layer 24, suitability for polarized sunglasses can be improved.

[0140] 6 is incorporated into a windshield glass, the second retardation layer 28 may be disposed on the first glass plate (not shown) side facing the vehicle exterior, and the first retardation layer 24 may be disposed on the second glass plate (not shown) side facing the vehicle interior. In this case, the first retardation layer 24 has the function of converting projected P-polarized light (linearly polarized light) into circularly polarized light that is reflected by the cholesteric liquid crystal layer 26. In contrast, the second retardation layer 28 has the function of optically compensating for light incident from outside the windshield glass, and optical compensation by the second retardation layer 28 can improve suitability for polarized sunglasses.

[0141] 6 is incorporated into a windshield glass, and when the first retardation layer 24 is disposed on the first glass plate (not shown) side facing the vehicle exterior and used as an optical compensation layer, the front retardation of the first retardation layer 24 at a wavelength of 550 nm is preferably 50 to 160 nm. When the direction corresponding to the vertically upward direction of the surface of the second glass plate when the windshield glass having the reflective film 20 is mounted on a vehicle is defined as 0°, the angle of the slow axis of the first retardation layer 24 is preferably 10° to 50° or −50° to −10°.

[0142] Furthermore, when the first retardation layer 24 is used for the purpose of converting linearly polarized light into circularly polarized light, the first retardation layer 24 is preferably configured to provide a front retardation of λ / 4, or may be configured to provide a front retardation of 3λ / 4. The angle of the slow axis may be oriented so as to convert incident linearly polarized light into circularly polarized light. In the above embodiment, the front retardation of the first retardation layer 24 at a wavelength of 550 nm is preferably 100 to 450 nm, more preferably 120 to 200 nm or 300 to 400 nm. Furthermore, the direction of the slow axis of the first retardation layer 24 is preferably determined depending on the incident direction of projection light for projecting an image and the sense of helix of the cholesteric liquid crystal layer when the reflective film 20 is used in a head-up display system.

[0143] [Other Embodiments of the Reflective Film] The reflective film may be provided with an A-plate, which is described as the first retardation layer 24, on both sides of the cholesteric liquid crystal layer 26, or may be provided with a polarization conversion layer, which is described as the second retardation layer 28, on both sides of the cholesteric liquid crystal layer 26. That is, the reflective film may be provided with an A-plate on both sides of the cholesteric liquid crystal layer, or may be provided with a polarization conversion layer on both sides of the cholesteric liquid crystal layer. When such a reflective film is incorporated into a windshield glass, the first retardation layer 24 or the second retardation layer 28 (polarization conversion layer) arranged on the second glass plate (not shown) side, which is the vehicle interior side, may have a function of converting projected P-polarized light (linearly polarized light) into circularly polarized light that can be reflected by the cholesteric liquid crystal layer 26. On the other hand, the first retardation layer 24 or the second retardation layer 28 (polarization conversion layer) arranged on the first glass plate (not shown) side, which is the vehicle exterior side, may have a function of optical compensation for light incident from outside the windshield glass.

[0144] Furthermore, in the reflective film 20, the cholesteric liquid crystal layer 26 has a plurality of regions with different helical pitches of the cholesteric liquid crystal phase along the thickness direction, and the cholesteric liquid crystal layer 26 has, in order from the transparent support 22 side, a region having a selective reflection center wavelength in the red (R) wavelength region, a region having a selective reflection center wavelength in the green (G) wavelength region, and a region having a selective reflection center wavelength in the blue (B) wavelength region. However, the cholesteric liquid crystal layer 26 may have, in order from the transparent support 22 side, a region having a selective reflection center wavelength in the blue (B) wavelength region, a region having a selective reflection center wavelength in the green (G) wavelength region, and a region having a selective reflection center wavelength in the red (R) wavelength region.

[0145] The average reflectance of the reflective film at an incident angle of 5° and a wavelength of 400 to 800 nm is preferably 25% or less, more preferably 20% or less, and even more preferably 15% or less. The lower limit is not particularly limited, but is, for example, 10% or more.

[0146] The average transmittance of the reflective film at wavelengths of 380 to 420 nm is preferably 40% or more, more preferably 45% or more, and even more preferably 50% or more. The upper limit is not particularly limited, but is, for example, 90% or less.

[0147] [Laminated Glass] The laminated glass of the present invention has a first glass plate, the above-mentioned reflective film, and a second glass plate, in this order. The reflective film is as described above. Hereinafter, one example of an embodiment of the laminated glass of the present invention will be described with reference to the drawings.

[0148] [First embodiment of laminated glass] Fig. 7 is a schematic diagram showing an example of the laminated glass of the present invention. The laminated glass 30 shown in Fig. 7 includes, in this order, a first glass plate 32, an interlayer 34, a reflective film 20, a heat seal layer 36, and a second glass plate 38. Note that in the laminated glass 30, the interlayer 34 and the heat seal layer 36 are optional components and may not be included in the laminated glass 30. The laminated glass 30 may also include a pressure-sensitive adhesive layer (OCA layer) instead of the heat seal layer 36. In Fig. 7, the reflective film 20 includes, in this order from the first glass plate 32 side, a second retardation layer 28, a cholesteric liquid crystal layer 26, a first retardation layer 24, and a transparent support 22.

[0149] When the laminated glass 30 is used as a windshield glass in a vehicle, curved glass is often used as the first glass sheet 32 ​​and the second glass sheet 38. In this case, if the first glass sheet 32 ​​is located on the exterior side of the vehicle and the second glass sheet 38 is located on the interior side of the vehicle, the concave side of the first glass sheet 32 ​​is positioned toward the second glass sheet 38, and the convex side of the second glass sheet 38 is positioned toward the first glass sheet 32.

[0150] <First Glass Sheet and Second Glass Sheet> Glass sheets that are generally used for windshield glass can be used for the glass sheets such as the first glass sheet 32 ​​and the second glass sheet 38. For example, glass sheets having a visible light transmittance of 80% or less, such as 73% or 76%, such as green glass with high heat insulation properties may be used.

[0151] The thickness of the first glass plate 32 and the second glass plate 38 is not particularly limited, but may be about 0.5 to 5.0 mm, preferably 1.0 to 3.0 mm, and more preferably 2.0 to 2.3 mm. The materials or thicknesses of the first glass plate 32 and the second glass plate 38 may be the same or different.

[0152] <Interlayer Film> The interlayer film 34 prevents glass from penetrating into the vehicle interior and shattering in the event of an accident, and in the example shown in Figure 7, it bonds the reflective film 20 and the first glass plate 32 together.

[0153] Any known interlayer film can be used as the interlayer film 34 (interlayer film sheet). For example, a resin film containing a resin selected from the group consisting of polyvinyl butyral (PVB), ethylene-vinyl acetate copolymer, and chlorine-containing resin can be used. The above-mentioned resin is preferably the main component of the interlayer film. Here, "main component" refers to a component that accounts for 50% or more by mass of the interlayer film.

[0154] Of the above resins, polyvinyl butyral or ethylene-vinyl acetate copolymer is preferred, and polyvinyl butyral is more preferred. The resin is preferably a synthetic resin. Polyvinyl butyral can be obtained by acetalizing polyvinyl alcohol with butyraldehyde. The degree of acetalization of the above polyvinyl butyral is preferably 40 to 85%, more preferably 60 to 75%.

[0155] The thickness of the intermediate film 34 is not particularly limited, and may be set in accordance with the forming material, etc., in the same manner as the intermediate film of a known windshield glass.

[0156] <Heat Seal Layer> The heat seal layer 36 is not particularly limited and may be, for example, a layer made of a coating type adhesive. In the example shown in Fig. 7, the reflective film 20 is attached to the second glass plate 38 by the heat seal layer 36.

[0157] The type of heat seal layer 36 is not particularly limited, and any known adhesive made of various types of coating type adhesive can be used as long as it can ensure the transparency required for a windshield glass and can bond the reflective film 20 and the second glass plate 38 with the required adhesive strength. The heat seal layer 36 may be the same as the intermediate film 34, such as PVB.

[0158] The heat seal layer 36 may be formed from an adhesive. From the viewpoint of the curing method, adhesives include hot melt type, heat curing type, light curing type, reaction curing type, and pressure sensitive adhesive type that does not require curing.

[0159] Although the embodiment of FIG. 7 shows the heat seal layer 36, the reflective film may be directly attached to the second glass plate 38.

[0160] <Adhesive Layer> When the laminated glass has an adhesive layer (OCA layer) instead of the heat seal layer 36, the adhesive layer may be formed using a highly transparent adhesive transfer tape (OCA tape). The highly transparent adhesive transfer tape may be a commercially available product for image display devices, particularly a commercially available product for the surface of the image display unit of an image display device. Examples of commercially available products include adhesive sheets (PD-S1, etc.) manufactured by Panac Corporation and adhesive sheets from the MHM series manufactured by Nichiei Kako Co., Ltd.

[0161] 7 illustrates a laminated glass having a first glass plate 32, an interlayer 34, a reflective film 20, a heat-seal layer 36, and a second glass plate 38 in this order, but the configuration of the laminated glass is not limited thereto, and may be, for example, a laminated glass having a first glass plate 32, a heat-seal layer 36, a reflective film 20, an interlayer 34, and a second glass plate 38 in this order. In the above embodiment, the reflective film 20 has, for example, a transparent support 22, a first retardation layer 24, a cholesteric liquid crystal layer 26, and a second retardation layer 28 arranged in this order from the first glass plate 32 side.

[0162] [Third embodiment of laminated glass] Fig. 8 is a schematic diagram showing an example of laminated glass of the present invention. The laminated glass 40 shown in Fig. 8 includes, in this order, a first glass plate 32, an interlayer film 34, a second glass plate 38, a heat seal layer 36, and a reflective film 20. Note that in the laminated glass 40, the heat seal layer 36 is an optional component and may not be included in the laminated glass 40. The laminated glass 40 may also include an adhesive layer (OCA layer) instead of the heat seal layer 36. In Fig. 8, the reflective film 20 includes, in this order from the first glass plate 32 side, a second retardation layer 28, a cholesteric liquid crystal layer 26, a first retardation layer 24, and a transparent support 22. Note that the components of the laminated glass 40 are the same as those of the laminated glass 30.

[0163] <Method for producing laminated glass> The method for producing the laminated glass of the present invention is not particularly limited, and the laminated glass can be produced according to a known method for producing laminated glass. For example, the laminated glass can be produced by a method in which, after laminating the respective components, heat treatment and pressure treatment (treatment using a rubber roller, etc.) are repeated several times, and finally heat treatment is performed under pressure using an autoclave, etc.

[0164] [Head-up display system] The head-up display system of the present invention includes a windshield glass made of the above-described laminated glass, and a projector that irradiates projection light onto the windshield glass.

[0165] An example of a head-up display system of the present invention is shown in Fig. 9. The head-up display system 110 of the present invention shown in Fig. 9 is an in-vehicle head-up display system, and includes a projector 112 for the head-up display system and a windshield glass 114.

[0166] 9 includes an image forming unit 120, an intermediate image screen 122, a reflecting member 124, and a concave mirror 126. In the following description, the projector 112 for the head-up display system will also be simply referred to as the "projector."

[0167] In the head-up display system 110 illustrated in Fig. 9, the projection light projected by the projector 112 passes through a transparent window 132 provided in the dashboard 130, is projected onto the windshield glass 114, and is observed by the observer OB. Note that, similar to a normal head-up display system, in the example illustrated in Fig. 9, the observer OB observes the image projected onto the windshield glass 114 as a virtual image through the windshield glass 114.

[0168] 9, projector 112 emits P-polarized projection light, and windshield glass 114 reflects the P-polarized light. The present invention is not limited to the embodiment shown in Fig. 9, and may be an embodiment in which the projector emits S-polarized projection light, and the windshield glass reflects the S-polarized light.

[0169] Each component of the head-up display system 110 will be described in detail below.

[0170] [Projector] In the projector 112, the image forming section 120 has a light source 134, a polarizing plate 136, and an optical deflector 138. The image forming section 120 is a so-called light beam scanner that forms an image by scanning a light beam.

[0171] The image forming unit 120 emits a light beam modulated according to the projection image from the light source 134, which is converted into P-polarized light by a polarizing plate 136 and secondarily scanned by an optical deflector 138. The projector 112 secondarily scans the light beam modulated according to the projection image by the optical deflector 138 and forms a real image on the intermediate image screen 122, which is then reflected along a predetermined optical path by the reflecting member 124 and the concave mirror 126. As described above, this reflected light passes through the transparent window 132 provided in the dashboard 130 and is projected onto the windshield glass 114, and is observed as a virtual image through the windshield glass 114 by the observer OB.

[0172] There are no particular limitations on the type of light source 134, and various light sources used for image formation can be used. Examples of the light source 134 include an LED (Light Emitting Diode), a discharge tube, and a laser light source. Note that the LED includes a light emitting diode and an organic light emitting diode (OLED).

[0173] The polarizing plate 136 converts the incident light beam into P-polarized light (P linearly polarized light). The type of polarizing plate 136 is not particularly limited, and various types of ordinary linear polarizing plates (linear polarizers) can be used. An example of the polarizing plate 136 is a polarizing plate formed by laminating thin films with different refractive index anisotropies. Examples of polarizing plates formed by laminating thin films with different refractive index anisotropies include those described in JP-A-9-506837. Specifically, polarizing plates can be formed using a wide variety of materials by processing them under conditions selected to obtain the refractive index relationship. Commercially available polarizing plates formed by laminating thin films with different refractive index anisotropies may be used. Examples of commercially available polarizing plates include DBEF (manufactured by 3M) and APF (Advanced Polarizing Film). Furthermore, general linear polarizing plates such as an absorptive polarizing plate containing an iodine compound and a reflective polarizing plate such as a wire grid can also be used as the polarizing plate 136. In the embodiment shown in Fig. 9, the polarizing plate 136 converts the incident light beam into P-polarized light (P-linearly polarized light), but the present invention is not limited to this embodiment, and the polarizing plate may convert the incident light beam into S-polarized light (S-linearly polarized light). In this case, the retardation layer may convert S-polarized light into P-polarized light. When the light is converted into S-polarized light by the polarizing plate, it may be possible to reduce the loss of light intensity at each subsequent reflecting member.

[0174] Various types of ordinary optical deflectors capable of secondarily scanning a light beam can be used as the optical deflector 138. Examples of the optical deflector 138 include a galvanometer mirror, a combination of a galvanometer mirror and a polygon mirror, and a microelectromechanical system (MEMS). Of these, MEMS is preferably used.

[0175] In the projector 112, the image forming unit 120 forms a projection image and an image by scanning a light beam, but the present invention is not limited to this. That is, in the projector of the present invention, various image forming means commonly used in projectors (imagers) of head-up display systems can be used as the image forming means. Examples of image forming means include LCDs (Liquid Crystal Displays) and LCOS (Liquid Crystal On Silicon) that use fluorescent tubes or liquid crystals. Another example of the image forming means is an organic electroluminescence (organic EL) display. Another example of the image forming means is DLPs (Digital Light Processing) that use DMDs (Digital Micromirror Devices).

[0176] The projection light emitted from the image forming unit 120 is then formed into a real image (visible image) by the intermediate image screen 122. There are no particular restrictions on the type of intermediate image screen 122, and any known intermediate image screen can be used as appropriate.

[0177] As described above, the projection light that has been formed into a real image on the intermediate image screen 122 is reflected along a predetermined optical path by the reflecting member 124 and the concave mirror 126. The types of the reflecting member 124 and the concave mirror 126 are not particularly limited, and known components can be used as appropriate. Although the projector 112 illustrated in FIG. 9 uses the reflecting member 124 and the concave mirror 126 as components that change the optical path of the projection light, the present invention is not limited to this. That is, the projector of the present invention may not include a concave mirror and may include only a reflecting member as a component that changes the optical path of the projection light, or may include one or more other optical reflecting elements in addition to the reflecting member and the concave mirror. As the optical reflecting element, in addition to a concave mirror and a normal mirror, a free-form mirror or the like can also be used. That is, the projector of the present invention can be configured using various optical reflecting elements as long as it includes the reflecting member of the present invention. In addition to the concave mirror described above, a diffractive reflecting element can also be used as a component that changes the optical path of the projection light. Diffractive reflective elements include holographic diffraction gratings and surface relief diffraction gratings.

[0178] [Windshield Glass] The windshield glass 114 refers to the window glass and windshield glass of vehicles such as cars and trains, airplanes, ships, motorcycles, and playground equipment. The windshield glass is preferably used as a windshield or windshield located in front of the vehicle in the traveling direction. The laminated glass of the present invention is used as the windshield glass 114. When the windshield glass made of the laminated glass of the present invention is used in a vehicle, the first glass sheet 32 ​​is disposed on the exterior side of the vehicle, and the second glass sheet 38 is disposed on the interior side of the vehicle.

[0179] Although there are no restrictions on the visible light transmittance of the windshield glass 114, a higher value is preferable. The visible light transmittance of the windshield glass 114 is preferably 70% or more, more preferably more than 70%, even more preferably 75% or more, and particularly preferably 80% or more. The above-mentioned visible light transmittance is preferably satisfied at all positions on the windshield glass 114, and is particularly preferably satisfied at positions where a reflective film is present.

[0180] [Uses] The head-up display system of the present invention can be used in a variety of applications, including, for example, an in-vehicle head-up display system.

[0181] [Composition] The composition of the present invention comprises a liquid crystal compound having a polymerizable group, a first polymerizable chiral agent whose helical twisting power changes upon irradiation with light, and a second polymerizable chiral agent having a rotational ability in the opposite direction to that of the first polymerizable chiral agent.

[0182] The composition may be any of the various components forming the composition layer in step 1 of the manufacturing method of the present invention described above. The content of the first polymerizable chiral agent in the composition is not particularly limited, but 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 not particularly limited, but is preferably 10% by mass or less, more preferably 5% by mass or less, and even more preferably 3.5% by mass or less. The content of the second polymerizable chiral agent in the composition is not particularly limited, but 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, relative to the total solid content of the composition. The upper limit is not particularly limited, but is preferably 10% by mass or less, more preferably 8% by mass or less, and even more preferably 6.0% by mass or less. The content of the polymerizable liquid crystal compound in the composition is not particularly limited, but 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 is preferably 99% by mass or less, more preferably 97% by mass or less, even more preferably 95% by mass or less, and particularly preferably 90% by mass or less.

[0183] The total content of the first polymerizable chiral agent and the second polymerizable chiral agent in the composition can be appropriately set to an amount that can provide the desired selective reflection center wavelength. Specific examples of the total content of the first polymerizable chiral agent and the second polymerizable chiral agent in the composition are preferably more than 5.0% by mass, more preferably 5.5% by mass or more, and even more preferably 6.0% by mass or more, relative to the total mass of the liquid crystal compound. There is no particular upper limit, but it is preferably 25% by mass or less, more preferably 20% by mass or less, and even more preferably 15% by mass or less. The content of the first polymerizable chiral agent can be appropriately set to an amount that can provide the desired selective reflection center wavelength, and is, for example, preferably 5 to 95% by mass, more preferably 10 to 90% by mass, and even more preferably 15 to 50% by mass, relative to the total content of the first polymerizable chiral agent and the second polymerizable chiral agent.

[0184] The composition may contain components other than the polymerizable liquid crystal compound, the first polymerizable chiral agent, and the second polymerizable chiral agent. Examples of such components include a polymerization initiator, a surfactant, and an alignment control agent. Specific examples of the polymerization initiator, surfactant, and alignment control agent include the same polymerization initiator, surfactant, and alignment control agent that may be contained in the composition layer in step 1 of the manufacturing method of the present invention described above. The content of the polymerization initiator in the composition is not particularly limited, but is preferably 0.01 to 20% by mass, and more preferably 0.5 to 10% by mass, based on the total solid content of the composition. The content of the alignment control agent in the composition is not particularly limited, but is preferably 0.01 to 10% by mass, more preferably 0.01 to 5% by mass, and particularly preferably 0.02 to 1% by mass, based on the total mass of the liquid crystal compound.

[0185] The composition may contain other components in addition to those described above, such as a polymerizable monomer, a crosslinking agent, a polymerization inhibitor, an antioxidant, an ultraviolet absorber, a light stabilizer, a colorant, and metal oxide fine particles.

[0186] The present invention will be described in more detail below with reference to the following examples. The materials, amounts used, ratios, treatment details, treatment procedures, etc. shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the following examples.

[0187] [Preparation of Samples] Various coating solutions used for preparing the reflective film are shown below.

[0188] [Liquid Crystal Layer Forming Composition a] The following components were mixed to prepare a liquid crystal layer forming composition a. ------------------------------------------------ Composition of composition a for forming liquid crystal layer------------------------------------------------ - Liquid crystal compound LC1 below: 100.0 parts by mass - Photopolymerization initiator (OXE01, manufactured by BASF): 3.0 parts by mass - Compound A below (adhesion improver): 1.2 parts by mass - Compound B below (alignment control agent): 0.1 part by mass - Chiral agent C1 shown in Table 1: Amount adjusted to achieve the target alignment state and selective reflection wavelength (blending amount A below) - Chiral agent C2 shown in Table 1: Amount adjusted to achieve the target alignment state and selective reflection wavelength (blending amount A below) - Solvent mixture (methyl ethyl ketone (MEK) / anone (mass ratio 70 / 30)): Amount to give a solids concentration of 20% by mass------------------------------------------------

[0189] <Blending Amounts of Chiral Agents C1 and C2 (Blending Amount A)> In the liquid crystal layer-forming composition a, the blending ratio and total blending amount of the chiral agents C1 and C2 were set so that the liquid crystal layer-forming composition a satisfied the following conditions: (Note that the types of chiral agents C1 and C2 contained in the liquid crystal layer-forming composition a differ for each Example, and the helical twisting power exhibited by each chiral agent also differs depending on the type. Therefore, when the liquid crystal layer-forming composition a is used to form a cholesteric liquid crystal alignment state in which the lower layer has a horizontal alignment and the upper layer has a selective reflection wavelength of 901 nm according to the predetermined procedure set forth in the conditions below, the blending ratio and total blending amount of the chiral agents C1 and C2 required to form the desired alignment state differ for each Example.)

[0190] (Conditions) After forming a coating film of the liquid crystal layer-forming composition a with a thickness of 1.3 μm, a retardation layer (lower layer) and a selective reflection layer 1 (upper layer) were formed according to the same procedure as that described later in (Preparation of liquid crystal layer A), and the lower layer exhibited horizontal alignment, and the upper layer had a selective reflection wavelength of 901 nm.

[0191] The components used are listed below.

[0192] -Liquid crystal compound LC1-

[0193] -Compound A-

[0194] -Compound B-

[0195] [Liquid crystal layer forming composition b] The following components were mixed to prepare liquid crystal layer forming composition b. ---------------- Composition of liquid crystal layer forming composition b -------------------------------- - 100.0 parts by mass of the above liquid crystal compound LC1 - 4.0 parts by mass of photopolymerization initiator (OXE01, manufactured by BASF) - 0.03 parts by mass of the above compound B (alignment control agent) - Chiral agent C1 shown in Table 1, amount adjusted to achieve the target alignment state and selective reflection wavelength (blending amount B below) - Chiral agent C2 shown in Table 1, amount adjusted to achieve the target alignment state and selective reflection wavelength (blending amount B below) - Mixed solvent (MEK / anone (mass ratio 70 / 30)), amount to give a solids concentration of 25% by mass --------------------------------

[0196] <Blending Amounts of Chiral Agents C1 and C2 (Blending Amount B)> In liquid crystal layer-forming composition b, the blending ratio and total blending amount of chiral agent C1 and chiral agent C2 were set so that liquid crystal layer-forming composition b satisfied the following conditions: (Note that in each example of liquid crystal layer-forming composition b, the types of chiral agent C1 and chiral agent C2 contained therein differ, and the helical twisting power exhibited by each chiral agent also differs depending on the type. Therefore, when liquid crystal layer-forming composition b is used to form a cholesteric liquid crystal alignment state in which the selective reflection wavelength of the lower layer is 715 nm and the selective reflection wavelength of the upper layer is 560 nm according to the predetermined procedure set forth in the conditions below, the blending ratio and total blending amount of chiral agent C1 and chiral agent C2 required to form the desired alignment state differ in each example.)

[0197] (Conditions) After forming a coating film of the liquid crystal layer-forming composition b with a thickness of 1.0 μm, a selective reflection layer 2 (lower layer) and a selective reflection layer 3 (upper layer) were formed in the same manner as in the procedure described later (Preparation of Liquid Crystal Layer B). When this was done, the selective reflection wavelength of the lower layer was 715 nm, and the selective reflection wavelength of the upper layer was 560 nm.

[0198] [Composition t1 for forming second retardation layer (A)] The following components were mixed to prepare a composition t1 for forming second retardation layer (A). ------------------------------------------------ Composition of composition t1 for forming second retardation layer (A)------------------------------------------------ - 100.0 parts by mass of the above liquid crystal compound LC1 - 1.0 part by mass of photopolymerization initiator (OXE01, manufactured by BASF) - 0.25 parts by mass of the following compound C (alignment control agent) - Mixed solvent (MEK / anone (mass ratio 85 / 15)) in an amount to give a solids concentration of 30% by mass

[0199] -Compound C- The numerical values ​​of the repeating units in Compound C are based on mole percentages.

[0200] [Composition t2 for forming second retardation layer (B) (polarization conversion layer)] The following components were mixed to prepare a composition t2 for forming a second retardation layer (B). ------------------------------------------------ Composition of composition t2 for forming second retardation layer (B)------------------------------------------------ - 100.0 parts by mass of the above liquid crystal compound LC1 - 1.0 part by mass of photopolymerization initiator (OXE01, manufactured by BASF) - 0.25 parts by mass of the above compound C (alignment control agent) - Chiral agent C2 listed in Table 1, an amount adjusted to achieve the target alignment state and selective reflection wavelength (blending amount T below) - Mixed solvent (MEK / anone (mass ratio 85 / 15)), an amount to give a solids concentration of 30% by mass ------------------------------------------------

[0201] <Amount of chiral agent C2 (amount T)> In the composition t2 for forming the second retardation layer (B), the amount of chiral agent C2 was set so that the composition t2 for forming the second retardation layer (B) satisfied the following condition: (Condition) After forming a coating film of the composition t2 for forming the second retardation layer (B) with a thickness of 1.6 μm, the coating film was irradiated with 300 mJ / cm 2 of a metal halide lamp with a wavelength of 330 nm or less cut off in an environment of 50° C. with an oxygen concentration of 100 ppm by volume or less. ２ When the liquid crystal phase is fixed by exposure to an integrated light amount of 1000 nm, the selective reflection wavelength becomes 8500 nm.

[0202] [Composition h for forming heat-seal layer] The following components were mixed to prepare composition h for forming heat-seal layer. -------------------------------- Composition of composition h for forming heat-seal layer-------------------------------- Photopolymerization initiator (Omnirad 127, manufactured by IGM Resins B.V.) 2.0 parts by mass Particle dispersion (AC-1011F3) (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd.) 50.0 parts by mass Binder (CLARITY LA4285, manufactured by Kuraray) 95.5 parts by mass Mixed solvent (MEK / butyl acetate (prepared to have a mass ratio of 50 / 50 including the butyl acetate used in the dispersion)) Amount to give a solids concentration of 10% by mass --------------------------------

[0203] The chiral agents C1 and C2 shown in Table 1 are shown below. Compounds 1B to 4B and compound R2 are chiral agents whose helical twisting power changes upon irradiation with light (ultraviolet light (365 nm) described below).

[0204] -Compound 1A-

[0205] -Compound 1B-

[0206] -Compound 2B-

[0207] -Compound 3B-

[0208] -Compound 4B-

[0209] -Compound R1-

[0210] -Compound R2-

[0211] [Preparation and Evaluation of Reflective Film] Hereinafter, a method for preparing a reflective film and its evaluation will be described. In the preparation procedure of the reflective film in each example, the procedure for preparing the liquid crystal layer B using the liquid crystal layer-forming composition b corresponds to the preparation method of the present invention described in the upper part.

[0212] [Examples 1 to 3, Comparative Example 1] (Preparation of Liquid Crystal Layer A) A liquid crystal layer-forming composition a was applied onto a TAC (triacetyl cellulose) film on which an alignment film had been formed, so that the film thickness after drying would be 1.3 μm. After application, the film was left to stand at room temperature for 15 seconds, and then heated in a 60°C atmosphere for 30 seconds. Thereafter, ultraviolet light (wavelength 365 nm) was applied at 60 mJ / cm in an atmosphere of 40°C. ２ After that, the sample was irradiated with 300 mJ / cm 2 of a metal halide lamp with wavelengths of 330 nm or less cut off in a 50°C environment with an oxygen concentration of 100 ppm by volume or less. ２ The cholesteric liquid crystal phase was fixed by exposing the TAC film to light having an integrated light amount of 10 ...

[0213] (Preparation of Liquid Crystal Layer B) Next, the liquid crystal layer-forming composition b was applied onto the liquid crystal layer A so that the film thickness after drying would be 1.0 μm. After application, the composition was left to stand at room temperature for 15 seconds, and then heated in a 60° C. atmosphere for 30 seconds. Thereafter, ultraviolet light (wavelength 365 nm) was applied at 60 mJ / cm in an atmosphere of 40° C. ２ After that, the sample was irradiated with 300 mJ / cm 2 of a metal halide lamp with wavelengths of 330 nm or less cut off in a 50°C environment with an oxygen concentration of 100 ppm by volume or less. ２to fix the cholesteric liquid crystal phase, thereby forming a liquid crystal layer B having a selective reflection layer 2 and a selective reflection layer 3 on the liquid crystal layer A. That is, the liquid crystal layer-forming composition b was used to simultaneously form the selective reflection layer 2 and the selective reflection layer 3 on the liquid crystal layer A. That is, a cholesteric liquid crystal layer having a plurality of regions with different helical pitches along the thickness direction was formed.

[0214] (Preparation of Second Retardation Layer (A)) Next, the composition t1 for forming the second retardation layer (A) was applied onto the liquid crystal layer B so that the film thickness after drying would be 1.6 μm. After application, the composition t1 was irradiated with 300 mJ / cm 2 using a metal halide lamp that cuts off wavelengths of 330 nm or less in an environment of 50° C. with an oxygen concentration of 100 volume ppm or less. ２ The liquid crystal phase was fixed by exposure so that the integrated light amount was 1000 times the total amount of light of the liquid crystal layer B, thereby forming a second retardation layer (A) on the liquid crystal layer B.

[0215] The reflective film prepared by the above procedure (hereinafter also referred to as "reflective film T") was used to carry out various evaluations described later.

[0216] Examples 4 to 6 and Comparative Examples 2 and 3 Example 4 Except for changing the types of chiral compound C1 and chiral agent C2, the liquid crystal layer B was produced by the same production method as in Example 1. Next, a composition t1 for forming a second retardation layer (A) was applied onto the obtained liquid crystal layer B so that the film thickness after drying would be 1.6 μm. After application, the composition t1 was irradiated with 300 mJ / cm 2 of a metal halide lamp that cuts off wavelengths of 330 nm or less in an environment of 50° C. with an oxygen concentration of 100 volume ppm or less. ２ The liquid crystal phase was fixed by exposing the film to an integrated light amount of 100 ppm or less, thereby forming a second retardation layer (A) on the liquid crystal layer B (reflective film T). Subsequently, the heat seal layer forming composition h was further applied to the surface of the second retardation layer (A) side so that the film thickness after drying would be 0.7 μm. After application, the film was placed in a solvent atmosphere by sealing with a cover at room temperature and left to stand for 15 seconds. Thereafter, the film was heated in a 120 ° C. atmosphere for 60 seconds, and then irradiated with 300 mJ / cm 2 with a mercury lamp (without a wavelength cut filter) in a room temperature environment with an oxygen concentration of 100 volume ppm or less. ２The liquid crystal phase was fixed by exposing the film to an integrated light amount of 1000 to obtain a reflective film with a heat seal layer (hereinafter also referred to as "reflective film H with a heat seal layer").

[0217] (Examples 5 and 6, and Comparative Examples 2 and 3) The composition t1 for forming the second retardation layer (A) or the composition t2 for forming the second retardation layer (B) was applied onto the liquid crystal layer B obtained by the preparation method of Example 3 or Comparative Example 1 so that the film thickness after drying would be 1.6 μm. After application, the composition t1 was applied in an environment of 50° C. with an oxygen concentration of 100 volume ppm or less, and irradiated with 300 mJ / cm 2 with a metal halide lamp that cuts off wavelengths of 330 nm or less. ２ The liquid crystal phase was fixed by exposing the film to an integrated light amount of 100 ppm or less, thereby forming a second retardation layer (A) or a second retardation layer (B) (polarization conversion layer) on the liquid crystal layer B (reflective film T). Subsequently, a heat seal layer-forming composition h was further applied to the surface of the second retardation layer (A) or the second retardation layer (B) side so that the film thickness after drying would be 0.7 μm. After application, the film was placed in a solvent atmosphere by sealing with a cover at room temperature and left to stand for 15 seconds. Thereafter, the film was heated in a 120 ° C. atmosphere for 60 seconds, and then irradiated with 300 mJ / cm 2 with a mercury lamp (without a wavelength cut filter) in a room temperature environment with an oxygen concentration of 100 volume ppm or less. ２ The liquid crystal phase was fixed by exposing the film to light so that the integrated light amount was 1000 times the amount of light obtained ... liquid crystal phase was fixed, thereby obtaining a reflective film H with a heat seal layer.

[0218] The reflective film H with a heat seal layer produced by the above procedure was used to carry out various evaluations described later.

[0219] [Various Evaluations] <Spectral Measurement of Film Alone> (Reflection Spectral Measurement) Using a spectrophotometer (V-670, manufactured by JASCO Corporation), P polarized light and S polarized light were incident from a direction of 5° relative to the normal direction of the film from the second retardation layer side (second retardation layer (A) or second retardation layer (B) side) of the reflective film T obtained by the production method of Examples 1 to 6, and the reflectance was measured in the range of 350 to 900 nm. In addition, the obtained spectra of P polarized light and S polarized light were averaged to obtain a reflection spectrum. The reflective films T obtained by the production methods of Examples 1 to 6 all had an average reflectance of 15% or less in the wavelength range of 400 to 800 nm.

[0220] (Transmission spectrum measurement) Furthermore, using the same spectrophotometer, for the reflective films T obtained by the production methods of Examples 1 to 6, P polarized light and S polarized light were incident from the normal direction of the film (front 0°) from the second retardation layer side (second retardation layer (A) or second retardation layer (B) side), and the transmittance was measured from 350 to 900 nm. The obtained spectra of P polarized light and S polarized light were averaged to obtain a transmission spectrum. All of the reflective films T obtained by the production methods of Examples 1 to 6 had an average transmittance of 50% or more in the wavelength range of 380 to 420 nm.

[0221] <Durability Evaluation 1 (Heat Treatment in an Environment at 140°C for 85 Minutes)> (Examples 1 to 3 and Comparative Example 1) The second retardation layer (A) side of the reflective film T of Examples 1 to 3 and Comparative Example was attached to a 2 mm thick glass with a 10 μm thick adhesive. In addition, the support side (TAC film side) was sandwiched and fixed with the same 2 mm thick glass, and heat treatment (heat treatment) was performed in an environment at 140°C for 85 minutes.

[0222] The reflection spectrum of the reflective film T bonded to the glass before heating and the reflective film T bonded to the glass after heating (a sample in which the 2 mm thick glass for fixation was removed after heating) was measured by the following procedure. (Reflection spectrum measurement) Using a spectrophotometer (V-670 manufactured by JASCO Corporation), P-polarized light and S-polarized light were incident from the glass side at a direction of 5° relative to the normal direction of the glass, and the reflectance from 350 to 900 nm was measured. The obtained P-polarized and S-polarized light spectra were averaged to obtain the reflection spectrum.

[0223] (Measurement of wavelength shift amount Δ of reflection spectrum before and after heating) Each position of wavelength 700 nm, wavelength 550 nm, and wavelength 450 nm in the reflection spectrum of the reflective film T before heating (note that in the reflection spectrum of the reflective film T, each position of wavelength 700 nm / wavelength 550 nm / wavelength 450 nm typically corresponds to a peak / valley / bottom) was set as an observation point (A ７００ , A ５５０ , A ４５０The reflection spectrum of the reflective film T before heating and the reflection spectrum of the reflective film T after heating were compared, and the reflection spectrum of the reflective film T after heating was determined to be the same as the observation point (A ７００ , A ５５０ , A ４５０ ) were obtained (observation point A ７００ Wavelength after heating: X (nm), observation point A ５５０ Wavelength after heating: Y (nm), observation point A ４５０ The wavelength after heating is Z (nm). The wavelength corresponding to the observation point is, for example, observation point A. ７００ For example, when the observation point at a wavelength of 700 nm in the reflection spectrum of the reflective film T before heating is a peak position, if the peak position in the reflection spectrum of the reflective film T after heating is observed at a wavelength of 690 nm, then the observation point A after heating ７００ The wavelength corresponding to this is 690 nm. Note that although the case of the peak position has been described above, for example, when the position of a wavelength of 700 nm in the reflection spectrum of the reflective film T before heating corresponds to the intermediate position between the peak and the valley of the reflection spectrum, the wavelength at which this intermediate position is located in the reflection spectrum of the reflective film T after heating corresponds to the corresponding wavelength. Next, the wavelength shift amount S before and after heating at each observation point is calculated using the following formulas (1) to (3): ７００、 S ５５０ , and S ４５０ Next, S ７００、 S ５５０ , and S ４５０ The arithmetic mean value (see formula (4)) of the above was calculated and used as the wavelength shift amount Δ (nm) of the reflection spectrum before and after heating.

[0224] Formula (S1) S ７００ = | (Wavelength X nm (after heating)) - (Wavelength 700 nm (before heating)) | Formula (S2) S ５５０ = | (Wavelength Y nm (after heating)) - (Wavelength 550 nm (before heating)) | Formula (S3) S ４５０ = | (Wavelength Znm (after heating)) - (Wavelength 450 nm (before heating)) | Formula (S4) Δ=(S ７００ +S ５５０ +S ４５０ ) / 3

[0225] The wavelength shift Δ (nm) of the reflection spectrum before and after heating was evaluated based on the following evaluation criteria. The results are shown in Table 1. (Evaluation criteria) "A": Δ≦10 nm "B": 10 nm<Δ≦15 nm "C": 15 nm<Δ

[0226] <Durability Evaluation 2 (Heat Treatment for 24 Hours in an Environment of 90°C / 80% RH)> (Examples 1 to 3 and Comparative Example 1) The second retardation layer (A) side of the reflective film T of Examples 1 to 3 and Comparative Example was attached to a 2 mm thick glass with a 10 μm thick adhesive, and heat treatment was carried out for 24 hours in an environment of 90°C / 80% RH. For the reflective film T before and after heating, reflection spectrum measurement was carried out in the same manner as in durability evaluation 1. Furthermore, based on the reflective film T before and after heating, the wavelength shift amount Δ (nm) of the reflection spectrum before and after heating was determined and evaluated in the same manner as in durability evaluation 1. The results are shown in Table 1.

[0227] <Durability Evaluation 3 (heat and vacuum drawing (140°C, 2 hours) ⇒ heat and pressure application (140°C, 1.2 MPa, 45 minutes))> (Examples 4 to 6 and Comparative Examples 2 and 3) The reflective film H with a heat seal layer produced in Examples 4 to 6 and Comparative Examples 2 and 3 was laminated with other members in the following arrangement. The reflective film H with a heat seal layer was laminated so that the heat seal layer side faced the first glass side. First glass / reflective film H with a heat seal layer / interlayer / PET film for release / second glass Next, the above laminate was subjected to heat treatment 1 (vacuum drawing at 140°C for 2 hours) to achieve a temporary pressure-bonded state. Thereafter, the temporary pressure-bonded laminate was subjected to heat treatment 2 (at a high temperature and high pressure of 140°C and 1.2 MPa for 45 minutes). The reflection spectrum of the reflective film H with a heat seal layer before temporary pressure-bonding (heat treatment 1) and after heat and pressure-bonding (heat treatment 2) was measured using the same method as in durability evaluation 1. When measuring the reflection spectrum of the heat-sealable reflective film H after thermocompression bonding, the intermediate film / peel-off PET film / second glass were removed from the sample after thermocompression bonding, and the above measurement was performed. Furthermore, based on the heat-sealable reflective film H before pre-compression bonding (heat treatment 1) and after thermocompression bonding (heat treatment 2), the wavelength shift amount Δ (nm) of the reflection spectrum before pre-compression bonding (heat treatment 1) and after thermocompression bonding (heat treatment 2) was determined using the same method as in durability evaluation 1. Next, evaluation was performed based on the wavelength shift amount Δ (nm) of the reflection spectrum before and after heating, according to the following evaluation criteria. The results are shown in Table 1. (Evaluation criteria) "A": Δ≦5 nm "B": 5 nm<Δ≦10 nm "C": 10 nm<Δ

[0228] <Durability Evaluation 4 (Heat Treatment for 24 Hours in an Environment of 90°C / 80% RH)> (Examples 4 to 6 and Comparative Examples 2 and 3) The reflective film H with a heat seal layer after the above-mentioned durability evaluation 3 was subjected to heat treatment (heat treatment) for 24 hours in an environment of 90°C / 80% RH. The reflection spectrum of the reflective film H with a heat seal layer before and after heating was measured in the same manner as in durability evaluation 1. Furthermore, the wavelength shift amount Δ (nm) of the reflection spectrum before and after heating was determined and evaluated based on the reflective film H with a heat seal layer before and after heating in the same manner as in durability evaluation 3. The results are shown in Table 1.

[0229] The thickness of the selective reflection layer 1 was calculated from a fitting analysis of the reflection spectrum of the liquid crystal layer A, and the thicknesses of the selective reflection layers 2 and 3 were calculated from a fitting analysis of the transmission spectrum of the liquid crystal layer B.

[0230] In the liquid crystal layer forming composition b of Example 1, the content of chiral compound C1 was 3.1 mass % based on the total solid content of the composition, and the content of chiral compound C2 was 4.8 mass % based on the total solid content of the composition. The weighted average helical twisting power before light irradiation in step 3 was 28.6 μm －１ The weighted average helical twisting strength after the light irradiation in step 3 was 36.6 μm －１ In the liquid crystal layer-forming composition b of Example 2, the content of chiral compound C1 was 2.1 mass % based on the total solid content of the composition, and the content of chiral compound C2 was 4.7 mass % based on the total solid content of the composition. The weighted average helical twisting power before light irradiation in step 3 was 33.5 μm －１ The weighted average helical twisting strength after the light irradiation in step 3 was 42.8 μm －１ In the liquid crystal layer-forming composition b of Example 3, the content of chiral compound C1 was 1.9 mass % based on the total solid content of the composition, and the content of chiral compound C2 was 4.8 mass % based on the total solid content of the composition. The weighted average helical twisting power before light irradiation in step 3 was 34.2 μm －１ The weighted average helical twisting strength after the light irradiation in step 3 was 43.6 μm －１In the liquid crystal layer-forming composition b of Example 4, the content of chiral compound C1 was 1.6 mass % based on the total solid content of the composition, and the content of chiral compound C2 was 5.5 mass % based on the total solid content of the composition. The weighted average helical twisting power before light irradiation in step 3 was 31.9 μm －１ The weighted average helical twisting strength after the light irradiation in step 3 was 40.7 μm －１ In addition, the content of chiral compound C1 in the liquid crystal layer-forming compositions b of Examples 5 and 6 was 1.9 mass % based on the total solid content of the composition, and the content of chiral compound C2 was 4.8 mass % based on the total solid content of the composition. The weighted average helical twisting power before light irradiation in step 3 was 34.2 μm －１ The weighted average helical twisting strength after the light irradiation in step 3 was 43.6 μm －１ It was.

[0231] The "Selective Reflection Layer Curing Rate" column in Table 1 indicates the curing rate of the liquid crystal layer B. The curing rate was measured by the ATR (Attenuated Total Reflection) method. Specifically, the measurement was carried out by the following procedure. The film formed up to the liquid crystal layer B in the production of the above-mentioned reflective film T and reflective film H with a heat seal layer was used as a sample film, and the sample film was placed in an ATR measurement device so that the liquid crystal layer B side was pressed against the prism of the measurement section, and light was incident (penetration depth of light into the sample film: approximately 1 μm), and the reflected light reflected by the sample film was measured.

[0232]

[0233] From the results in Table 1, it is clear that the reflective films of the examples, which have a cholesteric liquid crystal layer obtained by the manufacturing method of the present invention, have reduced changes in the reflection spectrum. Furthermore, from a comparison of the examples, it was confirmed that when the first polymerizable chiral agent and the second polymerizable chiral agent each have two or more polymerizable groups, the changes in the reflection spectrum are further reduced.

[0234] [Preparation of Windshield Glass] Windshield glasses were prepared by the following procedure using the reflective films H with heat seal layers prepared in Examples 4 to 6, and it was confirmed that all of them functioned as head-up displays.

[0235] [Preparation of Windshield Glass 1] Glass plates measuring 260 mm in length, 330 mm in width, and 2 mm in thickness were prepared as the first and second glass plates, and a 0.76 mm-thick PVB film (manufactured by Sekisui Chemical Co., Ltd.) was prepared as the interlayer. Next, the reflective film H with a heat seal layer, the first glass plate, the second glass plate, and the interlayer were laminated using the following two arrangement methods: arrangement method (1) and arrangement method (2). In arrangement method (1), the reflective film H with a heat seal layer was arranged so that the heat seal layer side faced the first glass plate, and in arrangement method (2), the reflective film H with a heat seal layer was arranged so that the heat seal layer side faced the second glass plate. Arrangement method (1): First glass plate (vehicle exterior) / reflective film H with heat seal layer / interlayer / second glass plate (vehicle interior) Arrangement method (2): First glass plate (vehicle exterior) / interlayer / reflective film H with heat seal layer / second glass plate (vehicle interior) Next, the two types of laminates obtained were held at 140°C and 10 kPa for 2 hours, and then heated in an autoclave (manufactured by Kurihara Seisakusho) at 135°C and 1.3 MPa for 45 minutes to remove air bubbles, thereby obtaining two types of windshield glass.

[0236] [Preparation of Windshield Glass 2] Glass plates measuring 260 mm in length, 330 mm in width, and 2 mm in thickness were prepared as the first, second, and third glass plates. A 0.76 mm-thick PVB film (manufactured by Sekisui Chemical Co., Ltd.) was also prepared as a mold for fixing the support (TAC film) side of the heat seal layer of the interlayer and reflective film H with a heat seal layer. Next, the reflective film H with a heat seal layer, the first glass plate, the second glass plate, the third glass plate, the interlayer, the fixing PVB, and the third glass plate were laminated according to the arrangement method (3) shown below. In the arrangement method (3), however, the reflective film H with a heat seal layer was arranged so that the heat seal layer side faced the second glass plate. Arrangement method (3): First glass plate (vehicle exterior side) / interlayer / second glass plate (vehicle interior side) / reflective film H with heat seal layer / fixing PVB / third glass plate Next, the obtained laminate was held at 140°C and 10 kPa for 2 hours, and then heated in an autoclave (manufactured by Kurihara Seisakusho) at 135°C and 1.3 MPa for 45 minutes to remove air bubbles. Subsequently, the fixing PVB and the third glass plate were peeled from the support (TAC film) surface of the reflective film H with heat seal layer, thereby obtaining a windshield glass in which the reflective film H with heat seal layer was bonded to the outside of a laminated glass consisting of the first glass plate and the second glass plate.

[0237] REFERENCE SIGNS LIST 10 Substrate LC Liquid crystal compound 12 Composition layer 12B Upper region 12A Lower region 22 Transparent support 24 First retardation layer 26 Cholesteric liquid crystal layer 28 Second retardation layer 20 Reflective film 30, 40 Laminated glass 32 First glass plate 34 Intermediate film 36 Heat seal layer 38 Second glass plate 110 Head-up display system 112 Projector 114 Windshield glass 120 Image forming unit 122 Intermediate image screen 124 Reflective member 126 Concave mirror 130 Dashboard 132 Transmitting window 134 Light source 136 Polarizing plate 138 Optical deflector OB Observer

Claims

1. Step 1 involves forming a composition layer comprising a liquid crystal compound having polymerizable groups, a first polymerizable chiral agent whose helical induced force changes upon light irradiation, and a second polymerizable chiral agent having a rotational property in the opposite direction to that of the first polymerizable chiral agent. Step 2 involves orienting the liquid crystal compound in the composition layer, Step 3 involves irradiating the first polymerizable chiral agent with light of a wavelength capable of altering its helical inductive force under conditions of an oxygen concentration of 1 volume percent or more. The process includes step 4, which involves curing the composition layer to fix the orientation of the liquid crystal compound and forming a cholesteric liquid crystal layer having multiple regions with different helical pitches along the thickness direction. A method for manufacturing a cholesteric liquid crystal layer, comprising a step 5 between step 3 and step 4 in which the composition layer is subjected to a heat treatment, or in step 3 in which the composition layer is further subjected to a heat treatment when irradiated with light.

2. The method for producing a cholesteric liquid crystal layer according to claim 1, wherein the first polymerizable chiral agent and the second polymerizable chiral agent each have two or more polymerizable groups.

3. A method for producing a cholesteric liquid crystal layer according to claim 1 or 2, wherein the first polymerizable chiral agent and the second polymerizable chiral agent include a substructure selected from the group consisting of an isosorbide substructure, an isomannide substructure, and a binaphthyl substructure.

4. The method for producing a cholesteric liquid crystal layer according to claim 1 or 2, wherein the first polymerizable chiral agent has a photoisomerizable double bond within its molecule.

5. The method for producing a cholesteric liquid crystal layer according to claim 4, wherein the first polymerizable chiral agent includes a photoisomerization site selected from the group consisting of a cinnamoyl site, a chalcone site, and a stilbene site.

6. The method for manufacturing a cholesteric liquid crystal layer according to claim 1 or 2, wherein the thickness of the cholesteric liquid crystal layer is 10 μm or less.

7. A cholesteric liquid crystal layer having a fixed cholesteric liquid crystal phase, It has multiple regions with different helical pitches in the thickness direction, The cholesteric liquid crystal layer is a layer formed using a composition comprising a liquid crystal compound having polymerizable groups, a first polymerizable chiral agent whose helical induced force changes upon light irradiation, and a second polymerizable chiral agent having a rotational property in the opposite direction to that of the first polymerizable chiral agent.

8. The cholesteric liquid crystal layer according to claim 7, wherein the first polymerizable chiral agent and the second polymerizable chiral agent each have two or more polymerizable groups.

9. A reflective film having the cholesteric liquid crystal layer described in claim 7.

10. A reflective film having, in this order, a first phase difference layer, a cholesteric liquid crystal layer according to claim 7, and a second phase difference layer.

11. A reflective film as described in the claim, wherein the average reflectance at an incident angle of 5° and a wavelength of 400-800 nm is 15% or less.

12. The reflective film according to claim 10, wherein the average transmittance at wavelengths of 380 to 420 nm is 50% or more.

13. A laminated glass comprising a first glass plate, a reflective film according to claim 9, and a second glass plate in this order.

14. The laminated glass according to claim 13, wherein a heat-seal layer or adhesive layer is provided between the first glass plate and the reflective film, or between the second glass plate and the reflective film.

15. A laminated glass comprising, in this order, a first glass plate, an interlayer, a second glass plate, and the reflective film described in claim 9.

16. The laminated glass according to claim 15, wherein a heat-seal layer or an adhesive layer is provided between the second glass plate and the reflective film.

17. A head-up display system comprising a windshield glass made of laminated glass according to any one of claims 13 to 16, and a projector that projects light onto the windshield glass.

18. The head-up display system according to claim 17, wherein the projector emits P-polarized projection light.

19. A composition comprising a liquid crystal compound having polymerizable groups, a first polymerizable chiral agent whose helical induced force changes upon light irradiation, and a second polymerizable chiral agent having a rotational property in the opposite direction to that of the first polymerizable chiral agent.

20. The composition according to claim 19, wherein the first polymerizable chiral agent and the second polymerizable chiral agent each have two or more polymerizable groups.