JP6861793B2 - Manufacturing method of reflective layer - Google Patents

Description

The present invention relates to a method for producing a reflective layer.

The layer formed by fixing the cholesteric liquid crystal phase is known as a layer having a property of selectively reflecting either right-handed circularly polarized light or left-handed circularly polarized light in a specific wavelength range. Therefore, it has been developed for various purposes, and is used, for example, as a retardation layer (Patent Document 1). In Patent Document 1, the direction of the orientation regulating force of the alignment film is set to a random state, and the direction of the director of the liquid crystal compound in contact with the alignment film is randomized.

Japanese Unexamined Patent Publication No. 2005-49866

On the other hand, from the viewpoint of applying the layer formed by fixing the cholesteric liquid crystal phase to a projection screen or other projection image display member, it is required to expand the viewing angle.
More specifically, when light is incident from the normal direction of the surface of the layer formed by fixing the cholesteric liquid crystal phase, either right-handed circularly polarized light or left-handed circularly polarized light is selectively reflected. .. At that time, if the reflection is performed not only in the normal direction but also in the oblique direction, the visibility from the oblique direction is improved. That is, the reflective layer is required to have excellent characteristics of reflecting incident light in various directions (so-called diffuse reflectivity).
The present inventors prepared a reflective layer using the alignment film not subjected to the rubbing treatment described in Patent Document 1, and examined its diffuse reflectance. As a result, the diffuse reflectance satisfied the recent required level. It was not, and further improvement was needed.

An object of the present invention is to provide a method for producing a reflective layer having excellent diffuse reflectance in view of the above circumstances.

As a result of diligent studies on the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by a predetermined procedure.
That is, it was found that the above problem can be solved by the following configuration.

(1) A method for producing a reflective layer in which the cholesteric liquid crystal phase is fixed and the bright and dark parts derived from the cholesteric liquid crystal phase observed by a scanning electron microscope in a cross section are wavy.
A composition layer containing a liquid crystal compound having a polymerizable group and a chiral agent is formed, and the bright and dark parts derived from the cholesteric liquid crystal phase observed by a scanning electron microscope are wavy in the cross section of the formed composition layer. Step 1 to carry out the process of
It has step 2 in which the composition layer obtained in step 1 is subjected to an immobilization treatment.
A method for producing a reflective layer, wherein the viscosity of the composition constituting the composition layer is 2000 mPa · s or more during the immobilization treatment in step 2.
(2) The method for producing a reflective layer according to (1), wherein the viscosity is 10,000 mPa · s or more.
(3) The method for producing a reflective layer according to (1) or (2), which has a viscosity of 15,000 mPa · s or more.
(4) The method for producing a reflective layer according to any one of (1) to (3), wherein the immobilization treatment is a light irradiation treatment.
(5) The method for producing a reflective layer according to any one of (1) to (4), wherein the treatment in step 1 is a treatment for changing the spiral inducing force of the chiral agent contained in the composition layer.
(6) Any of (1) to (5), wherein the treatment in step 1 is a treatment of cooling or heating the composition layer to change the spiral-inducing force of the chiral agent contained in the composition layer. The method for producing a reflective layer according to the description.
(7) The treatment in step 1 heats the composition layer to orient the liquid crystal compound to form a cholesteric liquid crystal phase, and then the spiral inducing force of the chiral agent contained in the composition layer increases by 5% or more. The method for producing a reflective layer according to (5) or (6), which is a process for cooling the composition layer as described above.
(8) The method for producing a reflective layer according to (7), wherein the composition layer is cooled so that the temperature of the composition layer is lowered by 30 ° C. or more when the composition layer is cooled.
(9) The method for producing a reflective layer according to any one of (1) to (4), wherein the process in step 1 is a process of applying a voltage to the composition layer.
(10) The method for producing a reflective layer according to any one of (1) to (9), wherein the liquid crystal compound has a plurality of polymerizable groups.
(11) The method for producing a reflective layer according to any one of (1) to (10), wherein the content of the liquid crystal compound in the composition layer is 60% by mass or more.

According to the present invention, it is possible to provide a method for producing a reflective layer having excellent diffuse reflectance.

It is a schematic diagram when the cross section of the layer in a general cholesteric liquid crystal phase state was observed with a scanning electron microscope (SEM). It is a schematic diagram when the cross section of the reflective layer manufactured by the manufacturing method of this invention was observed by SEM.

Hereinafter, the present invention will be described in detail. The numerical range represented by using "~" in the present specification means a range including the numerical values before and after "~" as the lower limit value and the upper limit value.
Further, in the present specification, "(meth) acrylate" is a notation representing both acrylate and methacrylate, and "(meth) acryloyl group" is a notation representing both an acryloyl group and a methacryloyl group. "(Meta) acrylic" is a notation that represents both acrylic and methacrylic.

First, FIG. 1 shows a schematic cross-sectional view when a layer of a composition in a general cholesteric liquid crystal phase state is arranged on a substrate. As shown in FIG. 1, when the cross section of the layer 12a of the composition in the cholesteric liquid crystal phase state arranged on the substrate 10 is observed with a scanning electron microscope (SEM), usually, the stripes of the bright portion 14 and the dark portion 16 are observed. The pattern is observed. That is, in the cross section of the cholesteric liquid crystal phase, a layered structure in which bright portions 14 and dark portions 16 are alternately laminated is observed.
The two bright parts 14 and the three dark parts 16 in FIG. 1 correspond to one pitch of the spiral.
Generally, as shown in FIG. 1, the striped pattern (layered structure) of the bright portion 14 and the dark portion 16 is formed so as to be parallel to the surface of the substrate 10. In other words, the line forming the bright portion 14 (continuous line) and the line forming the dark portion 16 (continuous line) are parallel to the surface of the layer 12a of the composition. In such an embodiment, when light is incident from the normal direction of the layer 12a of the composition in the cholesteric liquid crystal phase state, the light is reflected in the normal direction, but the light is not easily reflected in the oblique direction. Poor diffuse reflectivity (see arrow in FIG. 1).

FIG. 2 shows a schematic cross-sectional view when the reflective layer obtained by the production method of the present invention is arranged on a substrate. As shown in FIG. 2, in the reflective layer 12b, the bright portion 14 and the dark portion 16 derived from the cholesteric liquid crystal phase have a wavy structure (undulation structure). That is, the line forming the bright portion 14 (continuous line) and the line forming the dark portion 16 (continuous line) become wavy. When light is incident on the reflective layer 12b having such a wavy structure (concavo-convex structure) from the normal direction of the reflective layer 12b, as shown in FIG. 2, a region in which the spiral axis of the liquid crystal compound is tilted. Therefore, a part of the incident light is reflected in an oblique direction (see the arrow in FIG. 2). That is, the reflective layer produced by the production method of the present invention is excellent in diffuse reflectivity.
In the production method of the present invention for producing the reflective layer as described above, the bright part and the dark part derived from the cholesteric liquid crystal phase in the composition layer are changed in a wavy shape by a predetermined treatment, and the composition layer in that state is changed. Is subjected to immobilization treatment to produce a predetermined reflective layer. In particular, when the viscosity of the composition constituting the composition layer is equal to or higher than a predetermined value during the immobilization treatment, a wavy structure is maintained in the bright and dark portions derived from the cholesteric liquid crystal phase obtained in step 1. It is easy to be fixed as it is, and it is easy to obtain a reflective layer having excellent diffuse reflectivity.

The method for producing a reflective layer of the present invention includes at least the following steps 1 and 2.
Step 1: A composition layer containing a liquid crystal compound having a polymerizable group and a chiral agent is formed, and bright and dark parts derived from the cholesteric liquid crystal phase observed by a scanning electron microscope in a cross section of the formed composition layer are formed. Step 2: Performing the wavy change treatment Step 2: Step of immobilizing the composition layer obtained in Step 1 The materials used in each step and the procedure of each step will be described in detail below. ..

<Step 1>
In step 1, a composition layer containing a liquid crystal compound having a polymerizable group and a chiral agent is formed, and bright and dark areas derived from the cholesteric liquid crystal phase observed with a scanning electron microscope in a cross section of the formed composition layer. This is a step of carrying out a process of changing the liquid crystal into a wavy shape.
In the following, first, the materials and members used in this step will be described in detail, and then the procedure of the step will be described in detail.

(Liquid crystal compound)
The type of liquid crystal compound is not particularly limited.
Generally, a liquid crystal compound can be classified into a rod-shaped type (rod-shaped liquid crystal compound) and a disk-shaped type (discotic liquid crystal compound, disk-shaped liquid crystal compound) according to its shape. Further, the rod-shaped type and the disk-shaped type are classified into a low molecular weight type and a high molecular weight type, respectively. A polymer generally refers to a polymer having a degree of polymerization of 100 or more (Polymer Physics / Phase Transition Dynamics, Masao Doi, p. 2, Iwanami Shoten, 1992). In the present invention, any liquid crystal compound can be used. Further, two or more kinds of liquid crystal compounds may be used in combination.

The liquid crystal compound has a polymerizable group. The type of the polymerizable group is not particularly limited, and a functional group capable of an addition polymerization reaction is preferable, and a polymerizable ethylenically unsaturated group or a ring-polymerizable group is more preferable. More specifically, as the polymerizable group, a (meth) acryloyl group, a vinyl group, a styryl group, an allyl group, an epoxy group, or an oxetane group is preferable, and a (meth) acryloyl group is more preferable.
The number of polymerizable groups is not particularly limited, and may be one or more. Among them, the number of polymerizable groups is preferably a plurality, more preferably 2 to 6, and even more preferably 2 to 4 in that the diffuse reflectance of the reflective layer is more excellent. ..

The molecular weight of the liquid crystal compound is not particularly limited, but 400 or more is preferable, and 700 or more is more preferable, because the viscosity of the composition during the immobilization treatment in step 2 can be easily controlled. The upper limit is not particularly limited, but in many cases it is 2000 or less (particularly in the case of low molecular weight type).
When a rod-shaped liquid crystal compound is used, a compound having 4 or more rings contained in the core portion of the mesogen group in the liquid crystal compound is preferable, and a compound having 5 or more rings is more preferable, from the viewpoint of controlling the viscosity.

As the liquid crystal compound, the liquid crystal compound represented by the following formula (I) is preferable in that the diffuse reflectance of the reflective layer is more excellent.

During the ceremony
A represents a phenylene group which may have a substituent or a trans-1,4-cyclohexylene group which may have a substituent.
L is a single bond, or -CH ₂ O-, -OCH ₂ -,-(CH ₂ ) ₂ OC (= O)-, -C (= O) O (CH ₂ ) _2- , -C (= O) O-, -OC (= O)-, -OC (= O) O-, -CH = CH-C (= O) O-, -OC (= O) -CH = CH-, -CH = Indicates a linking group selected from the group consisting of N-N = CH-, -C = N-, -N = C-, -C≡C-, and -NH-.
m represents an integer from 3 to 12
Sp ¹ and Sp ² are independently one or two in a single bond or a linear or branched alkylene group having 1 to 20 carbon atoms and a linear or branched alkylene group having 1 to 20 carbon atoms, respectively. One or more −CH ₂₋ are −O−, −S−, −NH−, −N (CH ₃ ) −, −C (= O) −, −OC (= O) −, or −C (= O) ) Indicates a linking group selected from the group consisting of groups substituted with O−.
Q ¹ and Q ² each independently represent a hydrogen atom or a polymerizable group selected from the group consisting of the groups represented by the following formulas (Q-1) to (Q-5), however. Either Q ¹ or Q ² shows a polymerizable group;

A is a phenylene group which may have a substituent or a trans-1,4-cyclohexylene group which may have a substituent. In the present specification, the phenylene group is preferably a 1,4-phenylene group.
The m A's may be the same or different from each other.
When a trans-1,4-cyclohexylene group which may have a substituent may be contained as A, it has a substituent represented by A in that the diffusion reflectivity of the reflective layer is more excellent. When the number of trans-1,4-cyclohexylene groups may be divided by m and the number is mc, a liquid crystal compound satisfying mc> 0.1 is preferable, and a liquid crystal satisfying 0.4 ≦ mc ≦ 0.8 is preferable. More preferably, it is a compound.
The mc is a number represented by the following formula.
mc = (number of trans-1,4-cyclohexylene groups which may have a substituent represented by A) ÷ m

m represents an integer of 3 to 12, preferably an integer of 3 to 9, more preferably an integer of 3 to 7, and even more preferably an integer of 3 to 5.

The substituent which the phenylene group and the trans-1,4-cyclohexylene group may have in the formula (I) is not particularly limited, and is, for example, an alkyl group, a cycloalkyl group, an alkoxy group, or an alkyl ether. Examples thereof include a substituent selected from the group consisting of a group, an amide group, an amino group, a halogen atom, and a group composed of a combination of two or more of the above-mentioned substituents. Further, examples of the substituent include the substituents represented by ^{-C (= O) -X 3 -Sp} 3 -Q 3 below. The phenylene group and the trans-1,4-cyclohexylene group may have 1 to 4 substituents. When having two or more substituents, the two or more substituents may be the same or different from each other.

As used herein, the alkyl group may be either linear or branched. The number of carbon atoms of the alkyl group is preferably 1 to 30, more preferably 1 to 10, and even more preferably 1 to 6. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, and a neopentyl group. Examples thereof include a 1,1-dimethylpropyl group, an n-hexyl group, an isohexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, and a dodecyl group. The description of the alkyl group in the alkoxy group is the same as the description of the above alkyl group. Further, in the present specification, specific examples of the alkylene group when referred to as an alkylene group include a divalent group obtained by removing one arbitrary hydrogen atom in each of the above-mentioned examples of an alkyl group. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

In the present specification, the number of carbon atoms of the cycloalkyl group is preferably 3 or more, more preferably 5 or more, preferably 20 or less, more preferably 10 or less, further preferably 8 or less, and particularly preferably 6 or less. Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group and the like.

Substituents that the phenylene group and the trans-1,4-cyclohexylene group may have include an alkyl group, an alkoxy group, and a group consisting of ^{-C (= O) -X 3-} Sp ^3- Q ^3. Substituents selected from are preferred. Here, X ³ is a single bond, -O -, - S-, or -N (Sp ⁴ -Q ⁴⁾ - or show, or the nitrogen atom forming the ring structure with Q ³ and Sp ³ Shown. Sp ³ and Sp ⁴ are independently one or two in a single bond or a linear or branched alkylene group having 1 to 20 carbon atoms and a linear or branched alkylene group having 1 to 20 carbon atoms, respectively. One or more −CH ₂₋ are −O−, −S−, −NH−, −N (CH ₃ ) −, −C (= O) −, −OC (= O) −, or −C (= O) ) Indicates a linking group selected from the group consisting of groups substituted with O−.
In Q ³ and Q ⁴ , each of the hydrogen atom, cycloalkyl group, and cycloalkyl group has one or more -CH ₂ − -O-, -S-, -NH-, and -N (CH _3). )-, -C (= O)-, -OC (= O)-, or -C (= O) O-substituted group, or represented by formulas (Q-1) to (Q-5). Shows any polymerizable group selected from the group consisting of the groups to be.

One or more -CH _2- in a cycloalkyl group are -O-, -S-, -NH-, -N (CH ₃ )-, -C (= O)-, -OC (= O) Specific examples of the group substituted with − or −C (= O) O− include a tetrahydrofuranyl group, a pyrrolidinyl group, an imidazolidinyl group, a pyrazoridinyl group, a piperidyl group, a piperazinyl group, and a morphornyl group. .. Of these, a tetrahydrofuranyl group is preferable, and a 2-tetrahydrofuranyl group is more preferable.

In formula (I), L is a single bond or −CH ₂ O−, −OCH ₂₋ , − (CH ₂ ) ₂ OC (= O) −, −C (= O) O (CH ₂ ) ₂ -, -C (= O) O-, -OC (= O)-, -OC (= O) O-, -CH = CH-C (= O) O-, -OC (= O) -CH = Indicates a linking group selected from the group consisting of CH-, -CH = N-N = CH-, -C = N-, -N = C-, -C≡C-, and -NH-. L is preferably −C (= O) O−, −OC (= O) −, or −NH−.
The m L's may be the same or different from each other.

Sp ¹ and Sp ² are independently one or two in a single bond or a linear or branched alkylene group having 1 to 20 carbon atoms and a linear or branched alkylene group having 1 to 20 carbon atoms, respectively. One or more −CH ₂₋ are −O−, −S−, −NH−, −N (CH ₃ ) −, −C (= O) −, −OC (= O) −, or −C (= O) Indicates a linking group selected from the group consisting of groups substituted with O−. Sp ¹ and Sp ² are carbons to which a linking group selected from the group consisting of -O-, -OC (= O)-, and -C (= O) O-, respectively, is bonded to both ends independently. Select from the group consisting of linear alkylene groups of numbers 1 to 10, -OC (= O)-, -C (= O) O-, -O-, and linear alkylene groups of 1 to 10 carbon atoms. It is preferably a linking group composed of one or a combination of two or more groups, and more preferably a linear alkylene group having 1 to 10 carbon atoms having —O— bonded to both ends.

Q ¹ and Q ² each independently represent a hydrogen atom or a polymerizable group selected from the group consisting of groups represented by the following formulas (Q-1) to (Q-5). However, ^{either Q 1} or Q ² shows a polymerizable group.

As the polymerizable group, an acryloyl group (formula (Q-1)) or a methacryloyl group (formula (Q-2)) is preferable.

Specific examples of the liquid crystal compound include a liquid crystal compound represented by the following formula (I-11), a liquid crystal compound represented by the formula (I-21), and a liquid crystal represented by the formula (I-31). Examples include compounds. In addition to the above, the compound represented by the formula (I) of JP2013-12631A, the compound represented by the formula (I) of JP2010-70543A, and the formula of JP-A-2008-291218. Compound represented by (I), compound represented by formula (I) of Patent No. 4725516, compound represented by general formula (II) of JP2013-087109, JP2007-176927 The compound described in paragraph 0043 of the above, the compound represented by the formula (1-1) of JP-A-2009-286885, the compound represented by the general formula (I) of WO2014 / 10325, JP-A-2016-81035. Examples thereof include compounds represented by the formula (1) of the publication, and known compounds described in the compounds represented by the formulas (2-1) and (2-2) of JP-A-2016-121339. ..

Liquid crystal compound represented by the formula (I-11)

In the formula, R ¹¹ represents a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, or −Z ¹² −Sp ¹² −Q ¹² .
L ¹¹ indicates a single bond, -C (= O) O-, or -OC (= O)-,
L ¹² indicates −C (= O) O−, −OC (= O) −, −C (= O) NR ²⁻ , or −NR ² C (= O) −.
R ² represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms.
Z ¹¹ and Z ¹² are independently single-bonded, -O-, -NH-, -N (CH ₃ )-, -S-, -C (= O) O-, -OC (= O)-, respectively. , -OC (= O) O-, ^{or, -C (= O) NR 12} -, - NR 12 C (= O) - indicates,
R ¹² indicates a hydrogen atom or −Sp ¹² −Q ¹²
Sp ¹¹ and Sp ¹² are each independently a single bond, a linear or branched alkylene group having from carbon atoms 1 be replaced by Q ¹¹ 12 or, carbon atoms, which may be substituted with Q ¹¹ In a linear or branched alkylene group of 1 to 12, any one or more of -CH ₂ -is given as -O-, -S-, -NH-, -N (Q ¹¹ )-, or -C (=). O)-indicates the linking group obtained by substituting with-
Q ¹¹ is a hydrogen atom, a cycloalkyl group, one in the cycloalkyl group or two or more -CH ₂ - is -O -, - S -, - NH -, - N (CH 3) -, - C (= A group consisting of groups substituted with O)-, -OC (= O)-, or -C (= O) O-, or groups represented by the formulas (Q-1) to (Q-5). Indicates a polymerizable group selected from
Q ¹² represents a polymerizable group selected from the group consisting of groups represented by hydrogen atom or formula (Q-1) ~ formula (Q-5),
l ¹¹ indicates an integer from 0 to 2
m ¹¹ indicates an integer of 1 or 2 and represents
n ¹¹ indicates an integer from 1 to 3 and represents
A plurality of R ^11, a plurality of L ^11, a plurality of L ^12, a plurality of l ^11, a plurality of Z ^11, a plurality of Sp ^11, and a plurality of Q ¹¹ may each be the same or different from each other.
Further, the liquid crystal compound represented by the formula (I-11) is polymerizable as ^{R 11 selected from the group consisting of groups in which Q 12} is represented by the formulas (Q-1) to (Q-5). It contains at least one of the base −Z ¹² −Sp ¹² −Q ^12.
The liquid crystal compound represented by formula (I-11) is, Z ¹¹ is -C (= O) O -, - OC (= O) -, - C (= O) NR 12 - or -NR ¹² C (= O) − and Q ¹¹ are polymerizable groups selected from the group consisting of the groups represented by the formulas (Q-1) to (Q-5) −Z ¹¹ −Sp ¹¹ −Q ¹¹ Is preferable. The liquid crystal compound represented by formula (I-11) as R ^11, Z ¹² is -C (= O) O -, - OC (= O) -, - C (= O) NR 12 - or −NR ¹² C (= O) − and Q ¹² are polymerizable groups selected from the group consisting of the groups represented by the formulas (Q-1) to (Q-5) −Z ¹² −Sp. ^It is preferably 12 −Q ^12.

The 1,4-cyclohexylene groups contained in the liquid crystal compound represented by the formula (I-11) are all trans-1,4-cyclohexylene groups.
As a preferable embodiment of the liquid crystal compound represented by the formula (I-11), L ¹¹ is a single bond, l ¹¹ is 1 (dicyclohexyl group), and Q ¹¹ is a formula (Q-1) to a formula (Q-5). ) Is a polymerizable group selected from the group consisting of the groups represented by).
As another preferred embodiment of the liquid crystal compound represented by the formula (I-11), m ¹¹ represents 2, l ¹¹ represents 0, and both ^{R 11} represent ^{−Z 12} −Sp ¹² −Q ^12. , Q ¹² and the like are compounds which are polymerizable groups selected from the group consisting of groups represented by the formula (Q-1) ~ formula (Q-5).

Liquid crystal compound represented by the formula (I-21)

In the formula, Z ²¹ and Z ²² each independently represent a trans-1,4-cyclohexylene group which may have a substituent or a phenylene group which may have a substituent.
Each of the above substituents is 1 to 4 substituents independently selected from the group consisting of ^{-CO-X 21-} Sp ^23- Q ^{23, an alkyl group, and an alkoxy group.}
m21 represents an integer of 1 or 2, n21 represents an integer of 0 or 1,
When m21 indicates 2, n21 indicates 0,
When m21 indicates 2, the two Z ^21s may be the same or different.
At ^{least one of Z 21} and Z ²² is a phenylene group which may have a substituent and is a phenylene group.
L ²¹ , L ²² , L ²³ and L ²⁴ are independently single-bonded or -CH ₂ O-, -OCH ₂ -,-(CH ₂ ) ₂ OC (= O)-, -C (= O). ) O (CH ₂ ) _2- , -C (= O) O-, -OC (= O)-, -OC (= O) O-, -CH = CH-C (= O) O-, and- Indicates a linking group selected from the group consisting of OC (= O) -CH = CH-.
X ²¹ indicates -O-, -S-, or -N (Sp ^25- Q ²⁵ )-or indicates a nitrogen atom that forms a ring structure with ^{Q 23} and Sp ^23.
r ²¹ represents an integer from 1 to 4
Sp ²¹ , Sp ²² , Sp ²³ , and Sp ²⁵ are independently single-bonded or linear or branched alkylene groups with 1 to 20 carbon atoms and linear or branched alkylene groups with 1 to 20 carbon atoms, respectively. One or more -CH ₂ − in the group is −O−, −S−, −NH−, −N (CH ₃ ) −, −C (= O) −, −OC (= O) −, Alternatively, a linking group selected from the group consisting of groups substituted with −C (= O) O− is indicated.
Q ²¹ and Q ²² each independently represent any polymerizable group selected from the group consisting of the groups represented by the formulas (Q-1) to (Q-5).
In Q ²³ _{, one or more -CH 2-} in hydrogen atom, cycloalkyl group, and cycloalkyl group are -O-, -S-, -NH-, -N (CH ₃ )-, -C (= Select from the group consisting of groups substituted with O)-, -OC (= O)-, or -C (= O) O-, and groups represented by the formulas (Q-1) to (Q-5). One of the polymerizable groups to be used, or when X ²¹ is a nitrogen atom forming a ring structure with ^{Q 23} and Sp ^{23, shows a single bond.}
Q ²⁵ is a hydrogen atom, a cycloalkyl group, one or two or more -CH ₂ in the cycloalkyl group - is -O -, - S -, - NH -, - N (CH 3) -, - C ( It consists of a group substituted with = O)-, -OC (= O)-, or -C (= O) O-, or a group represented by the formulas (Q-1) to (Q-5). ^{When Sp 25} is a single bond, indicating any polymerizable group selected from the group ^{, Q 25} is not a hydrogen atom.

The liquid crystal compound represented by the formula (I-21) preferably has a structure in which 1,4-phenylene groups and trans-1,4-cyclohexylene groups are alternately present, for example, m21 is 2. n21 is 0, and, if Z ²¹ are each optionally substituted trans-1,4-cyclohexylene group, an arylene group optionally having a substituent from Q ²¹ side, Alternatively, m21 is 1, n21 is 1, Z ²¹ is an arylene group which may have a substituent, and Z ²² is an arylene group which may have a substituent. Is preferable.

Liquid crystal compound represented by formula (I-31);

In the formula, R ³¹ and R ³² are independently selected groups from the group consisting of an alkyl group, an alkoxy group, and -C (= O) -X ^31- Sp ^33- Q ^33.
n31 and n32 each independently represent an integer from 0 to 4, respectively.
X ³¹ indicates a single bond, -O-, -S-, or -N (Sp ^34- Q ³⁴ )-or indicates a nitrogen atom forming a ring structure with ^{Q 33} and Sp ^33.
Z ³¹ represents a phenylene group which may have a substituent and represents
Z ³² represents a trans-1,4-cyclohexylene group which may have a substituent or a phenylene group which may have a substituent.
Each of the above substituents is 1 to 4 substituents independently selected from the group consisting of an alkyl group, an alkoxy group, and -C (= O) -X ^31- Sp ^33- Q ^33.
m31 represents an integer of 1 or 2, m32 represents an integer of 0-2,
When m31 and m32 indicate 2, the two Z ³¹ and Z ³² may be the same or different.
L ³¹ and L ³² are independently single-bonded or -CH ₂ O-, -OCH ₂ -,-(CH ₂ ) ₂ OC (= O)-, -C (= O) O (CH ₂ ). _2- , -C (= O) O-, -OC (= O)-, -OC (= O) O-, -CH = CH-C (= O) O-, and -OC (= O)- Indicates a linking group selected from the group consisting of CH = CH−.
Sp ³¹ , Sp ³² , Sp ³³ and Sp ³⁴ are independently single-bonded or linear or branched alkylene groups having 1 to 20 carbon atoms and linear or branched alkylene groups having 1 to 20 carbon atoms, respectively. One or more -CH ₂ − in the group is −O−, −S−, −NH−, −N (CH ₃ ) −, −C (= O) −, −OC (= O) −, Alternatively, a linking group selected from the group consisting of groups substituted with −C (= O) O− is indicated.
Q ³¹ and Q ³² each independently represent any polymerizable group selected from the group consisting of the groups represented by the formulas (Q-1) to (Q-5).
In Q ³³ and Q ³⁴ _{, one or more -CH 2} − in the hydrogen atom, cycloalkyl group, and cycloalkyl group are -O-, -S-, -NH-, and -N (CH _{3) independently of each other.} )-, -C (= O)-, -OC (= O)-, or -C (= O) O-substituted group, or in formulas (Q-1) to (Q-5) Representing any polymerizable group selected from the group consisting of the represented groups, Q ³³ may exhibit a single bond when forming a ring structure with ^{X 31} and Sp ^{33, with Sp 34} In the case of a single bond, Q ³⁴ is not a hydrogen atom.
As the liquid crystal compound represented by the formula (I-31), particularly preferable compounds include a compound in which Z ³² is a phenylene group and a compound in which m 32 is 0.

式（ＩＩ）において、黒丸は、式（Ｉ）の他の部分との結合位置を示す。式（ＩＩ）で表される部分構造は式（Ｉ）中の下記式（ＩＩＩ）で表される部分構造の一部として含まれていればよい。The compound represented by the formula (I) preferably has a partial structure represented by the following formula (II).

In formula (II), black circles indicate the bonding positions with other parts of formula (I). The partial structure represented by the formula (II) may be included as a part of the partial structure represented by the following formula (III) in the formula (I).

Wherein R ¹ and R ² each independently represent a hydrogen atom, an alkyl group, an alkoxy group, and is selected from the group consisting of groups represented by ^{-C (= O) -X 3 -Sp} 3 -Q 3 It is a base. Here, X ³ is a single bond, -O -, - S-, or -N (Sp ⁴ -Q ⁴⁾ - or show, or the nitrogen atom forming the ring structure with Q ³ and Sp ³ Shown. X ³ is preferably single bond or −O−. R ¹ and R ² is preferably a ^{-C (= O) -X 3 -Sp} 3 -Q 3. Further, ^{it is preferable that R 1} and R ² are the same as each other. The bonding position of R ¹ and R ² to each phenylene group is not particularly limited.

Sp ³ and Sp ⁴ are independently one or two in a single bond or a linear or branched alkylene group having 1 to 20 carbon atoms and a linear or branched alkylene group having 1 to 20 carbon atoms, respectively. The above -CH ₂ -is -O-, -S-, -NH-, -N (CH ₃ )-, -C (= O)-, -OC (= O)-, or -C (= O). Indicates a linking group selected from the group consisting of groups substituted with O−. As Sp ³ and Sp ⁴ , independently, a linear or branched alkylene group having 1 to 10 carbon atoms is preferable, a linear alkylene group having 1 to 5 carbon atoms is more preferable, and a direct chain having 1 to 3 carbon atoms is preferable. The alkylene group of the chain is more preferred.
In Q ³ and Q ⁴ , each of the hydrogen atom, cycloalkyl group, and cycloalkyl group has one or more -CH ₂ − -O-, -S-, -NH-, and -N (CH _3). )-, -C (= O)-, -OC (= O)-or -C (= O) O-substituted groups, or represented by formulas (Q-1) to (Q-5). Shows any polymerizable group selected from the group consisting of the groups to be.

The compound represented by the formula (I) also preferably has a structure represented by the following formula (II-2), for example.

In the formula, A ¹ and A ² independently represent a phenylene group which may have a substituent or a trans-1,4-cyclohexylene group which may have a substituent, and the above-mentioned substituents are Each is independently 1 to 4 substituents selected from the group consisting of an alkyl group, an alkoxy group, and -C (= O) -X ^3- Sp ^3- Q ^3.
L ¹ , L ² and L ³ are independently single-bonded or -CH ₂ O-, -OCH ₂ -,-(CH ₂ ) ₂ OC (= O)-, -C (= O) O ( CH ₂ ) _2- , -C (= O) O-, -OC (= O)-, -OC (= O) O-, -CH = CH-C (= O) O-, and -OC ( Indicates a linking group selected from the group consisting of = O) -CH = CH-.
n1 and n2 each independently represent an integer from 0 to 9, and n1 + n2 is 9 or less.
The definitions of Q ¹ , Q ² , Sp ¹ , and Sp ² are synonymous with the definitions of each group in the above formula (I). The definitions of X ³ , Sp ³ , Q ³ , R ¹ , and R ² are synonymous with the definitions of each group in the above formula (II).

Examples of the liquid crystal compound represented by the formula (I), which satisfies 0.4 ≦ mc ≦ 0.8, are as follows.

Two or more liquid crystal compounds may be used in combination. For example, two or more liquid crystal compounds represented by the formula (I) may be used in combination.
Among them, the liquid crystal compound represented by the above formula (I), which satisfies 0.4 ≦ mc ≦ 0.8, and the liquid crystal compound represented by the formula (I), 0.1. It is preferable to use a liquid crystal compound satisfying <mc <0.3.

Examples of the liquid crystal compound represented by the formula (I), which satisfies 0.1 <mc <0.3, are as follows.

As another preferred embodiment of the liquid crystal compound, a compound represented by the following formula (IV) can be mentioned.

Compound represented by formula (IV)

Wherein (IV), A ¹ represents an alkylene group having 2 to 18 carbon atoms, two or more CH ₂ not one CH ₂ or adjacent in the alkylene group, substituted by -O- May;
Z ¹ represents −C (= O) −, −OC (= O) −, or a single bond;
Z ² represents −C (= O) − or −C (= O) −CH = CH−;
R ¹ represents a hydrogen atom or a methyl group;
R ² is a hydrogen atom, a halogen atom, a linear alkyl group having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, a phenyl group which may have a substituent, a vinyl group, a formyl group, a nitro group and a cyano group. , Acetyl group, acetoxy group, N-acetylamide group, acryloylamino group, N, N-dimethylamino group, maleimide group, methacryloylamino group, allyloxy group, allyloxycarbamoyl group, alkyl group having 1 to 4 carbon atoms. Represents a certain N-alkyloxycarbamoyl group, N- (2-methacryloyloxyethyl) carbamoyloxy group, N- (2-acryloyloxyethyl) carbamoyloxy group, or a group represented by the following formula (IV-2). ;
L ¹ , L ² , L ³ and L ⁴ independently have an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkoxycarbonyl group having 2 to 5 carbon atoms, and 2 to 5 carbon atoms. Represents an acyl group, a halogen atom or a hydrogen atom of ^{4 , and at least one of L 1} , L ² , L ³ and L 4 represents a group other than a hydrogen atom.
-Z ^5- T-Sp-P formula (IV-2)
In formula (IV-2), P represents an acrylic group, a methacryl group or a hydrogen atom, Z ⁵ is a single bond, -C (= O) O-, -OC (= O)-, -C (= O). NR ¹ − (R ¹ represents a hydrogen atom or a methyl group), −NR ¹ C (= O) −, −C (= O) S−, or −SC (= O) −, where T is 1 , 4-Phenylene, Sp represents a divalent aliphatic group having 1 to 12 carbon atoms which may have a substituent, and one CH ₂ or two or more non-adjacent groups in the aliphatic group. CH ₂ may be replaced with −O−, −S−, −OC (= O) −, −C (= O) O− or −OC (= O) O−.

The compound represented by the above formula (IV) is preferably a compound represented by the following formula (V).

Compound represented by formula (V)

In equation (V), n1 represents an integer of 3-6;
R ¹¹ represents a hydrogen atom or a methyl group;
Z ¹² represents -C (= O)-or -C (= O) -CH = CH-;
R ¹² is represented by a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, a phenyl group, an acryloylamino group, a methacryloylamino group, an allyloxy group, or the following formula (IV-3). Represents a group.
-Z ^51- T-Sp-P formula (IV-3)
In formula (IV-3), P represents an acrylic or methacrylic group;
Z ⁵¹ represents -C (= O) O- or -OC (= O)-;
T stands for 1,4-phenylene;
Sp represents a divalent aliphatic group having 2 to 6 carbon atoms which may have a substituent group, one CH ₂ or non-adjacent two or more CH ₂ in the aliphatic groups, -O It may be substituted with −, −OC (= O) −, −C (= O) O− or −O (= O) OO−.
The above n1 represents an integer of 3 to 6, and is preferably 3 or 4.
The Z ¹² represents −C (= O) − or −C (= O) −CH = CH−, and preferably −C (= O) −.
The above R ¹² is represented by a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, a phenyl group, an acryloylamino group, a methacryloylamino group, an allyloxy group, or the above formula (IV-3). It is more preferable to represent a methyl group, an ethyl group, a propyl group, a methoxy group, an ethoxy group, a phenyl group, an acryloylamino group, a methacryloylamino group, or a group represented by the above formula (IV-3). , Methyl group, ethyl group, methoxy group, ethoxy group, phenyl group, acryloylamino group, methacryloylamino group, or a group represented by the above formula (IV-3) is more preferably represented.

The above R is intended as Me.
Specific examples of the compound represented by the formula (IV) include the compounds exemplified below.

As another preferred embodiment of the liquid crystal compound, a compound represented by the following formula (VI) can be mentioned.

Compound represented by formula (VI)

In formula (VI), Z ³ represents −C (= O) − or −CH = CH—C (= O) −;
Z ⁴ represents −C (= O) − or −C (= O) −CH = CH−;
R ³ and R ⁴ independently have a hydrogen atom, a halogen atom, a linear alkyl group having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, and an aromatic ring group and a cyclohexyl group which may have a substituent. , Vinyl group, formyl group, nitro group, cyano group, acetyl group, acetoxy group, acryloylamino group, N, N-dimethylamino group, maleimide group, methacryloylamino group, allyloxy group, allyloxycarbamoyl group, alkyl group carbon It is represented by an N-alkyloxycarbamoyl group having a number of 1 to 4, an N- (2-methacryloyloxyethyl) carbamoyloxy group, an N- (2-acryloyloxyethyl) carbamoyloxy group or the following formula (VI-2). Represents a group;
L ⁵ , L ⁶ , L ⁷ and L ⁸ independently have an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkoxycarbonyl group having 2 to 5 carbon atoms, and 2 to 5 carbon atoms. It represents an acyl group of 4, a halogen atom or a hydrogen atom, ^{and at least one of L 5} , L ⁶ , L ⁷ and L ⁸ represents a group other than a hydrogen atom.
−Z ⁵ −T-Sp-P Equation (VI-2)
In formula (VI-2), P represents an acrylic group, a methacryl group or a hydrogen atom, and Z ⁵ is -C (= O) O-, -OC (= O)-, -C (= O) NR ^1-. (R ¹ represents a hydrogen atom or a methyl group), -NR ¹ C (= O)-, -C (= O) S-, or -SC (= O)-, and T represents 1,4-phenylene. the stands, Sp represents a divalent aliphatic group having 1 to 12 carbon atoms which may have a substituent, two or more CH ₂ not one CH ₂ or adjacent in the aliphatic groups , -O-, -S-, -OC (= O)-, -C (= O) O- or -OC (= O) O- may be substituted.

The compound represented by the above formula (VI) is preferably a compound represented by the following formula (VII).

Compound represented by formula (VII)

In formula (VII), Z ¹³ represents -C (= O)-or -C (= O) -CH = CH-;
Z ¹⁴ represents −C (= O) − or −CH = CH—C (= O) −;
R ¹³ and R ¹⁴ are each independently a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, a phenyl group, an acryloylamino group, a methacryloylamino group, an allyloxy group, or the above formula ( Represents a group represented by IV-3).
The Z ¹³ represents −C (= O) − or −C (= O) −CH = CH−, and preferably −C (= O) −.
R ¹³ and R ¹⁴ are independently hydrogen atoms, linear alkyl groups having 1 to 4 carbon atoms, methoxy groups, ethoxy groups, phenyl groups, acryloylamino groups, methacryloylamino groups, allyloxy groups or the above formula (IV). Represents a group represented by -3), a methyl group, an ethyl group, a propyl group, a methoxy group, an ethoxy group, a phenyl group, an acryloylamino group, a methacryloylamino group, or a group represented by the above formula (IV-3). It is preferable to represent a methyl group, an ethyl group, a methoxy group, an ethoxy group, a phenyl group, an acryloylamino group, a methacryloylamino group, or a group represented by the above formula (IV-3).

Specific examples of the compound represented by the formula (VI) include the compounds exemplified below.

As another preferred embodiment of the liquid crystal compound, a compound represented by the following formula (VIII) can be mentioned.

Compound represented by formula (VIII)

Wherein (VIII), A ² and A ³ each independently represent an alkylene group having 2 to 18 carbon atoms, two or more CH ₂ not one CH ₂ or adjacent in the alkylene group , -O- may be substituted;
Z ⁵ represents −C (= O) −, −OC (= O) − or single bond;
Z ⁶ represents -C (= O)-, -C (= O) O- or a single bond;
R ⁵ and R ⁶ independently represent a hydrogen atom or a methyl group;
L ⁹ , L ¹⁰ , L ¹¹ and L ¹² independently have an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkoxycarbonyl group having 2 to 5 carbon atoms, and 2 to 5 carbon atoms. It represents an acyl group of 4, a halogen atom or a hydrogen atom, ^{and at least one of L 9} , L ¹⁰ , L ¹¹ and L ¹² represents a group other than a hydrogen atom.

The compound represented by the above formula (VIII) is preferably a compound represented by the following formula (IX).

Compound represented by formula (IX)

In formula (IX), n2 and n3 each independently represent an integer of 3-6;
R ¹⁵ and R ¹⁶ each independently represent a hydrogen atom or a methyl group.

In formula (IX), n2 and n3 each independently represent an integer of 3 to 6, and it is preferable that n2 and n3 are 4.
In the formula (IX), R ¹⁵ and R ¹⁶ each independently represent a hydrogen atom or a methyl group, ^{and it is preferable that the above R 15} and R ¹⁶ represent a hydrogen atom.

Specific examples of the compound represented by the formula (VIII) include the compounds exemplified below.

The liquid crystal compound can be produced by a known method.

The content of the liquid crystal compound in the composition layer is not particularly limited, but is preferably 50% by mass or more, more preferably 60% by mass or more, still more preferably 60 to 95% by mass, based on the total mass of the composition layer. Among them, the content of the liquid crystal compound having a plurality of polymerizable groups is preferably in the above range in that the diffuse reflectance of the reflective layer is more excellent.

(Chiral agent (chiral compound))
The type of chiral auxiliary is not particularly limited. The chiral agent may be liquid crystal or non-liquid crystal. The chiral agents are various known chiral agents (for example, liquid crystal device handbook, Chapter 3, Section 4-3, TN (Twisted Nematic), STN (Super Twisted Nematic) chiral agents, page 199, Japan Society for the Promotion of Science 142. You can choose from (described in 1989, edited by the committee). Chiral agents generally contain an asymmetric carbon atom. However, an axial asymmetric compound or a surface asymmetric compound that does not contain an asymmetric carbon atom can also be used as a chiral agent. Examples of axially asymmetric or surface asymmetric compounds include binaphthyl, helicene, paracyclophane, and derivatives thereof. The chiral agent may have a polymerizable group.

The content of the chiral agent in the composition is preferably 0.5 to 30% by mass with respect to the total mass of the liquid crystal compound. A smaller amount of chiral agent is preferred because it tends not to affect the liquid crystallinity. Therefore, as the chiral agent, a compound having a strong twisting force is preferable so that a desired twisting orientation of a spiral pitch can be achieved even in a small amount.
Examples of the chiral agent exhibiting such a strong twisting force include JP-A-2002-302487, JP-A-2002-80478, JP-A-2002-80851, JP-A-2002-179668, and JP-A-2002. 179670, 2002-338575, 2002-180051, 62-81354, WO2002 / 00195, 2011-241215, 2003-287623 , And the chiral agent described in JP-A-2014-034581, and LC-756 manufactured by BASF.

(Arbitrary ingredient)
The composition layer may contain components other than the liquid crystal compound and the chiral agent.

(Polymerization initiator)
The composition layer may contain a polymerization initiator.
The polymerization initiator is preferably a photopolymerization initiator capable of initiating a polymerization reaction by irradiation with ultraviolet rays. Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. No. 2,376,661 and US Pat. No. 2,376,670), acidoin ether (described in US Pat. No. 2,448,828), and α-hydrogen-substituted aromatic acidoin. Compounds (described in US Pat. No. 2722512), polynuclear quinone compounds (described in US Pat. Nos. 3,043127 and 2951758), combinations of triarylimidazole dimers and p-aminophenylketone (US Pat. No. 3,549,376). (Described in the specification), aclysine and phenazine compounds (Japanese Patent Laid-Open No. 60-105667, US Pat. No. 4,239,850), oxadiazole compounds (described in US Pat. No. 4,212,970), and the like.
The content of the polymerization initiator in the composition layer is not particularly limited, but is preferably 0.1 to 20% by mass, more preferably 1 to 10% by mass, based on the total mass of the liquid crystal compound.

(Orientation control agent)
The composition layer may contain an orientation control agent. The inclusion of the orientation control agent in the composition layer enables the formation of a stable or rapid cholesteric liquid crystal phase.
Examples of the orientation control agent include a fluorine-containing (meth) acrylate-based polymer, a compound represented by the general formulas (X1) to (X3) described in WO2011 / 162291, and paragraph [0007] of Japanese Patent Application Laid-Open No. 2012-211306. ] To [0029], the compounds described in paragraphs [0020] to [0031] of JP2013-47204A, the compounds described in paragraphs [0165] to [0170] of WO2016 / 909648, WO2016. / 092444 paragraphs [0077]-[0081] and general formulas (Cy201)-(Cy211) described in Japanese Patent No. 4592225. These compounds can reduce or substantially horizontally orient the molecules of the liquid crystal compound at the air interface of the layer. In addition, although "horizontal orientation" in the present specification means that the long axis of the liquid crystal molecule and the film surface are parallel, it does not require that they are strictly parallel, and in this specification, it is referred to as a horizontal plane. It shall mean an orientation with an inclination angle of less than 20 °.
The orientation control agent may be used alone or in combination of two or more.
The content of the orientation 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, based on the total mass of the liquid crystal compound.

(Other additives)
The composition layer is composed of one or more kinds of antioxidants, ultraviolet absorbers, sensitizers, stabilizers, plasticizers, chain transfer agents, polymerization inhibitors, defoamers, leveling agents, and thickeners. It may contain agents, flame retardants, surfactants, dispersants, and other additives such as colorants such as dyes and pigments.

The composition layer may contain a thickener for the purpose of increasing the viscosity of the composition layer.
As the thickener, one that can increase the viscosity without significantly disturbing the orientation of the liquid crystal is preferable, and for example, a polymer having a mesogen structure is preferable.
Further, for example, a compound having a hydrogen-bonding functional group is also preferable. As the hydrogen-bonding functional group, a hydroxyl group, an amino group, a carboxyl group, a sulfo group, an amide group, a urethane group, a urea group and the like are preferable.

(Procedure of step 1)
In step 1, first, the above-mentioned composition layer is prepared.
The method for producing the composition layer is not particularly limited, and examples thereof include a method in which a composition containing a liquid crystal compound and a chiral agent is applied onto a substrate to form a composition layer.

The substrate is a plate that supports the composition layer. Of these, a transparent substrate is preferable. The transparent substrate is intended to be a substrate having a visible light transmittance of 60% or more, and the transmittance is preferably 80% or more, more preferably 90% or more.
The material constituting the substrate is not particularly limited, and for example, a cellulose-based polymer, a polycarbonate-based polymer, a polyester-based polymer, a (meth) acrylic polymer, a styrene-based polymer, a polyolefin-based polymer, a vinyl chloride-based polymer, an amide-based polymer, or an imide. Examples thereof include based polymers, sulfone-based polymers, polyether sulfone-based polymers, and polyether ether ketone-based polymers.
The substrate may contain various additives such as UV (ultraviolet) absorbers, matting fine particles, plasticizers, deterioration inhibitors, and release agents.
The substrate preferably has low birefringence in the visible light region. For example, the phase difference of the substrate at a wavelength of 550 nm is preferably 50 nm or less, more preferably 20 nm or less.
The thickness of the substrate is not particularly limited, but is preferably 10 to 200 μm, more preferably 20 to 100 μm from the viewpoint of thinning and handleability.
The above thickness is intended as an average thickness, and the thickness of any five points on the substrate is measured and arithmetically averaged.

Further, when the above composition is applied, the composition may contain a solvent, if necessary.
Examples of the solvent include water and organic solvents. Examples of the organic solvent include amides such as N, N-dimethylformamide; sulfoxides such as dimethyl sulfoxide; heterocyclic compounds such as pyridine; hydrocarbons such as benzene and hexane; alkyls such as chloroform and dichloromethane. Halides; esters such as methyl acetate, butyl acetate, and propylene glycol monoethyl ether acetate; ketones such as acetone, methyl ethyl ketone, cyclohexanone, and cyclopentanone; tetrahydrofuran, and 1,2-dimethoxyethane, etc. Ethers; 1,4-butanediol diacetate; and the like. These may be used alone or in combination of two or more.

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

The film thickness of the composition layer arranged on the substrate is not particularly limited, but 0.1 to 20 μm is preferable, 0.2 to 15 μm is more preferable, and 0.5 is preferable in that the diffuse reflectance of the reflective layer is more excellent. 10 μm is more preferable.

Next, in the cross section of the formed composition layer, the bright part and the dark part derived from the cholesteric liquid crystal phase observed by the scanning electron microscope are changed into a wavy shape.
More specifically, in the cross section of the composition layer formed by the above procedure, the bright and dark portions derived from the cholesteric liquid crystal phase are usually parallel to the surface of the composition layer (in other words, the surface of the substrate). (See Fig. 1). That is, both the bright line (continuous line) and the dark line (continuous line) are linear so as to be parallel to the surface of the composition layer. By subjecting such a composition layer to a predetermined treatment, the bright and dark portions derived from the cholesteric liquid crystal phase are changed to be wavy (see FIG. 2). That is, by performing a predetermined treatment, the bright part (line forming the bright part) and the dark part (line forming the dark part) derived from the cholesteric liquid crystal phase observed by the scanning electron microscope in the cross section of the composition layer are straight lines, respectively. Change from a shape to a wavy shape.

The treatment for changing the bright and dark parts derived from the cholesteric liquid crystal phase so as to be wavy is not particularly limited, and the treatment for changing the spiral-inducing force of the chiral agent contained in the composition layer is preferable. For example, when the spiral inducing force of the chiral agent contained in the composition layer is increased, the twist of the liquid crystal compound is further increased in the composition layer, and as a result, the orientation of the cholesteric liquid crystal phase (inclination of the spiral axis) is changed. As a result, the linear bright and dark parts are changed to the bright and dark parts of the wavy structure (concave and convex structure), and a predetermined reflective layer (layer of the composition in the cholesteric liquid crystal phase state) is formed (FIG. 2). reference).

The spiral inducing force (HTP) of the chiral agent is a factor indicating the spiral orientation ability represented by the following formula (1).
Equation (1) HTP = 1 / (length of spiral pitch (unit: μm) x concentration of chiral agent)
The length of the spiral pitch refers to the length of the pitch P (= spiral period) of the spiral structure of the cholesteric liquid crystal phase in the composition layer, and is measured by the method described on page 196 of the Liquid Crystal Handbook (Maruzen Publishing Co., Ltd.). it can. Further, the concentration of the chiral agent is intended to be the concentration (mass%) of the chiral agent with respect to the total solid content in the composition layer.
The HTP value is affected not only by the type of chiral auxiliary but also by the type of liquid crystal compound contained in the composition layer. Therefore, for example, a composition containing a predetermined chiral agent X and a predetermined liquid crystal compound A and a composition containing a predetermined chiral agent X and a predetermined liquid crystal compound B different from the predetermined liquid crystal compound A are prepared and are the same. When both HTPs are measured by temperature, the values may differ. Further, the value of HTP differs depending on the length of the spiral pitch formed in the composition layer, and the length of the spiral pitch can be appropriately adjusted by the temperature of the composition layer. That is, the length of the spiral pitch can be adjusted by subjecting the composition layer to a cooling treatment or a heat treatment.

Above all, it is preferable to carry out a treatment in which the spiral inducing force of the chiral agent in the composition layer is increased by 5% or more.
When the spiral-inducing force of the chiral auxiliary increases by 5% or more, the spiral-inducing force of the chiral agent in the composition before the composition layer is subjected to a predetermined treatment (for example, cooling treatment) is defined as X, and the composition layer is predetermined. When the spiral inducing force of the chiral auxiliary in the composition layer after the treatment (for example, cooling treatment) is Y, the rate of increase Z represented by the following formula (2) is 5% or more. Intended.
Equation (2): Rate of increase Z (%) = {(YX) / X} × 100
The rate of increase Z is preferably 5% or more, more preferably 10% or more. 12% or more is more preferable in that the diffuse reflectance of the reflective layer is more excellent. The upper limit is not particularly limited, but it is often 40% or less.

As a treatment for changing the bright part and the dark part derived from the cholesteric liquid crystal phase so as to be wavy, it is preferable to cool or heat the composition layer to change the spiral inducing force of the chiral agent contained in the composition layer. ..
In particular, in a preferred embodiment, the composition layer is heated to orient the liquid crystal compound to form a cholesteric liquid crystal phase, and then the spiral-inducing force of the chiral agent contained in the composition layer changes (preferably, A process of cooling the composition layer (so that it rises by 10% or more) can be mentioned.
Hereinafter, the preferred embodiment will be described in detail.

As a heating condition for heating the composition layer, the composition layer is heated at 40 to 100 ° C. (preferably 60 to 100 ° C.) for 0.5 to 5 minutes (preferably 0.5 to 2 minutes). It is preferable to heat it.
Further, when cooling the composition layer in the state of the cholesteric liquid crystal phase, it is preferable to cool the composition so that the spiral inducing force of the chiral agent increases by 10% or more.
When cooling the composition, it is preferable to cool the composition layer so that the temperature of the composition layer is lowered by 30 ° C. or more because the diffuse reflectance of the reflective layer is more excellent. Among them, in that the above effect is more excellent, it is preferable to cool the composition layer so that the temperature is lowered by 40 ° C. or higher, and it is more preferable to cool the composition layer so that the temperature is lowered by 50 ° C. or higher. The upper limit of the reduced temperature range of the cooling treatment is not particularly limited, but is usually about 70 ° C.
In other words, the above cooling treatment is intended to cool the composition layer so that the temperature of the composition layer in the state of the cholesteric liquid crystal phase before cooling is T-30 ° C or lower. To do.
The cooling method is not particularly limited, and examples thereof include a method in which the substrate on which the composition layer is arranged is allowed to stand in an atmosphere of a predetermined temperature.

Although the treatment for cooling or heating the composition layer has been described in detail above, the treatment for changing the bright and dark parts derived from the cholesteric liquid crystal phase so as to be wavy is not limited to this embodiment.
For example, a process of applying a voltage to the composition layer can also be mentioned. The method of applying the voltage is not particularly limited, and examples thereof include a method of filling a horizontally oriented cell with ITO (Indium Tin Oxide) with a liquid crystal composition to form a composition layer and applying a voltage.
In addition to the method of applying voltage, a method of applying a magnetic field, a method of applying pressure, and the like can also be mentioned.

<Process 2>
The step 2 is a step of applying an immobilization treatment to the composition layer obtained in the step 1. By carrying out this step, the cholesteric liquid crystal phase in which the bright part and the dark part are wavy is fixed, and a desired reflective layer can be mentioned.
That is, the obtained reflective layer corresponds to a layer in which the cholesteric liquid crystal phase is fixed.
Here, the state in which the cholesteric liquid crystal phase is "immobilized" is the most typical and preferable mode in which the orientation of the liquid crystal compound which is the cholesteric liquid crystal phase is maintained. It is not limited to this, and specifically, in the temperature range of 0 to 50 ° C., and more severely, -30 to 70 ° C., the layer is not fluid, and the layer is oriented by an external field or an external force. It shall mean a state in which the fixed orientation form can be kept stable without causing a change. In the present invention, as will be described later, it is preferable to fix the orientation state of the cholesteric liquid crystal phase by a curing reaction that proceeds by irradiation with ultraviolet rays.
In the layer in which the cholesteric liquid crystal phase is fixed, it is sufficient that the optical properties of the cholesteric liquid crystal phase are retained in the layer, and it is necessary that the composition in the layer finally exhibits liquid crystallinity. Absent.

The method of immobilization treatment is not particularly limited, and examples thereof include photo-curing treatment and thermosetting treatment. Among them, the light irradiation treatment is preferable, and the ultraviolet irradiation treatment is more preferable. Such an immobilization treatment is preferably a polymerization reaction by light irradiation (particularly ultraviolet irradiation), and more preferably a radical polymerization reaction by light irradiation (particularly ultraviolet irradiation).
A light source such as an ultraviolet lamp is used for ultraviolet irradiation.
The amount of ultraviolet irradiation energy is not particularly limited, but is generally preferably about ^{0.1 to 0.8 J / cm 2.} The time for irradiating the ultraviolet rays is not particularly limited, but may be appropriately determined from the viewpoints of both sufficient strength and productivity of the obtained reflective layer.

During the immobilization treatment in step 2, the viscosity of the composition constituting the composition layer becomes 2000 mPa · s or more. As described above, when the viscosity of the composition constituting the composition layer is equal to or higher than the above value, the structure of the cholesteric liquid crystal phase in which the bright and dark parts obtained in step 1 are wavy is maintained and fixed. Be made.
Among them, the viscosity is preferably 10,000 mPa · s or more, and more preferably 15,000 mPa · s or more, in that the diffuse reflectance of the reflective layer is more excellent. The upper limit is not particularly limited, but in many cases it is 50,000 mPa · s or less, and more often it is 40,000 mPa · s or less.

The viscosity of the composition constituting the composition layer can be adjusted by changing the type of the component (liquid crystal compound, chiral agent, etc.) contained in the composition.
In particular, in order to achieve the above viscosity, the content of the liquid crystal compound in the composition layer is preferably in the above-mentioned preferable range. Further, the liquid crystal compound is preferably a liquid crystal compound having a plurality of polymerizable groups.

As a method for measuring the viscosity of the composition constituting the composition layer, a known viscosity measuring machine (for example, rheometer RS600 (manufactured by HAAKE)) is used to measure the viscosity of the composition constituting the composition layer. There is a way to do it.
In the above measurement, a part of the composition layer may be scraped off to prepare a sample for measurement, and the viscosity at the temperature at the time of the immobilization treatment may be measured using the sample. Alternatively, a predetermined amount of each predetermined component constituting the composition layer may be mixed to prepare a sample for measurement, and the sample may be used to measure the viscosity at the temperature during the immobilization treatment.
The above viscosity is the viscosity at the time of the immobilization treatment. For example, when the immobilization treatment (for example, light irradiation treatment) is carried out under the condition of 30 ° C., the viscosity at 30 ° C. is the viscosity at the time of the immobilization treatment. Corresponds to the viscosity of the case.

<Reflective layer>
By the above manufacturing method, a reflective layer having a wavy structure in a bright portion and a dark portion in a cross-sectional SEM observation diagram as shown in FIG. 2 is formed.
The reflective layer is a layer having a cholesteric liquid crystal structure and having a structure in which the angle formed by the spiral axis and the surface of the reflective layer changes periodically. That is, the reflective layer has a cholesteric liquid crystal structure, and the cholesteric liquid crystal structure gives a striped pattern of bright and dark parts in a cross-sectional view of the reflective layer observed by a scanning electron microscope, and a line formed by the bright and dark parts. It is a reflective layer in which the angle between the normal and the surface of the reflective layer changes periodically.

A plurality of reflective layers may be laminated.
For example, after forming the reflection layer X having a predetermined selective reflection wavelength on the substrate by the above-mentioned method, the reflection layer Y having a selective reflection wavelength different from that of the reflection layer X may be formed by the same procedure.

<Use>
The reflective layer (cholesteric liquid crystal layer) is a layer having a cholesteric liquid crystal phase (cholesteric liquid crystal structure) having a predetermined wavy structure, and is preferably a layer formed by fixing the cholesteric liquid crystal phase.
The reflective layer is a layer that exhibits selective reflection characteristics with respect to light in a predetermined wavelength range. The reflective layer functions as a circularly polarized light selective reflection layer that selectively reflects either right-handed circularly polarized light or left-handed circularly polarized light in the selective reflection wavelength range and transmits the circularly polarized light of the other sense. A film containing one or more reflective layers can be used for various purposes. In a film containing two or more reflective layers, the sense of circularly polarized light reflected by each reflective layer may be the same or vice versa depending on the application. Further, the center wavelength of the selective reflection described later of each reflection layer may be the same or different depending on the application.

In the present specification, the term "sense" for circularly polarized light means whether it is right-handed circularly polarized light or left-handed circularly polarized light. The sense of circular polarization is right-handed circularly polarized light when the tip of the electric field vector turns clockwise as time increases when viewed as the light travels toward you, and left-handed when it turns counterclockwise. Defined as circularly polarized. In the present specification, the term "sense" may be used for the twisting direction of the spiral of the cholesteric liquid crystal. The selective reflection by the cholesteric liquid crystal reflects the right circularly polarized light when the twist direction (sense) of the spiral of the cholesteric liquid crystal is right, transmits the left circularly polarized light, and reflects the left circularly polarized light when the sense is left, and right. Transmits circularly polarized light.

For example, a film including a reflective layer exhibiting selective reflection characteristics in the visible light wavelength range (wavelength 400 to 750 nm) can be used as a screen and a half mirror for displaying a projected image. Further, by controlling the reflection band, it can also be used as a color filter or a filter for improving the color purity of the display light of the display (see, for example, Japanese Patent Application Laid-Open No. 2003-294948).
Further, the reflective layer can be used for various purposes such as a polarizing element, a reflective film, an antireflection film, a viewing angle compensating film, a holography, and an alignment film, which are constituent elements of an optical element.
Hereinafter, the application as a member for displaying a projected image, which is a particularly preferable application, will be described.

With the above function of the reflective layer, it is possible to form a projected image by reflecting the circularly polarized light of either sense at the wavelength showing selective reflection of the projected light. The projected image may be displayed on the surface of the projected image display member and visually recognized as such, or may be a virtual image that appears above the projected image display member when viewed from the observer.

The center wavelength λ of the selective reflection depends on the pitch P (= spiral period) of the spiral structure in the cholesteric liquid crystal phase, and follows the relationship between the average refractive index n of the reflective layer and λ = n × P. Here, the central wavelength λ of the selective reflection of the reflection layer means a wavelength at the center of gravity of the reflection peak of the circularly polarized reflection spectrum measured from the normal direction of the reflection layer. As can be seen from the above equation, the center wavelength of selective reflection can be adjusted by adjusting the pitch of the spiral structure. That is, in order to adjust the n value and the P value, for example, to selectively reflect either right-handed circularly polarized light or left-handed circularly polarized light with respect to blue light, the central wavelength λ is adjusted to make an apparent selection. The central wavelength of reflection can be in the wavelength range of 450 to 495 nm. The apparent center wavelength of selective reflection means the wavelength at the center of gravity of the reflection peak of the circular polarization reflection spectrum of the reflection layer measured from the observation direction during practical use (when used as a projection image display member). To do. Since the pitch of the cholesteric liquid crystal phase depends on the type of chiral agent used together with the liquid crystal compound or the concentration thereof added, a desired pitch can be obtained by adjusting these. For the measurement method of spiral sense and pitch, refer to "Introduction to Liquid Crystal Chemistry Experiment", edited by Liquid Crystal Society of Japan, Sigma Publishing, 2007, p. 46, and "Liquid Crystal Handbook", Liquid Crystal Handbook Editorial Committee, Maruzen, p. 196. Can be used.

In addition, full-color projected images can be displayed by producing reflection layers having apparent center wavelengths of selective reflection in the red light wavelength region, green light wavelength region, and blue light wavelength region, and stacking them. It is possible to manufacture a member for displaying a projected image.

By adjusting the center wavelength of the selective reflection of each reflection layer according to the emission wavelength range of the light source used for projection and the usage mode of the projected image display member, it is possible to display a clear projected image with high light utilization efficiency. In particular, by adjusting the center wavelength of the selective reflection of the reflective layer according to the emission wavelength range of the light source used for projection, it is possible to display a clear color projected image with high light utilization efficiency.

Further, for example, the projected image display member can be made into a half mirror that can be used as a combiner of a head-up display by having a structure that is transparent to light in the visible light region. The projected image display half mirror can visually display the image projected from the projector, and when the projected image display half mirror is observed from the same side on which the image is displayed, the opposite side is displayed. You can observe the information or landscape on the side at the same time.

Hereinafter, the features of the present invention will be described in more detail with reference to Examples and Comparative Examples. The materials, amounts used, ratios, treatment contents, treatment procedures, etc. shown in the following examples can be appropriately changed as long as they do not deviate from the gist of the present invention. Therefore, the scope of the present invention should not be construed as limited by the specific examples shown below.

<Preparation of liquid crystal composition>
The components shown in Table 1 below were mixed to prepare liquid crystal compositions 1 to 6. The amounts of each component are all parts by mass.

Each component in Table 1 above is shown below.

Rod-shaped liquid crystal compound 101

Rod-shaped liquid crystal compound 102

Rod-shaped liquid crystal compound 201

Rod-shaped liquid crystal compound 202

Rod-shaped liquid crystal compound 203

Rod-shaped liquid crystal compound 204

Polymer A

Chiral agent A

Chiral agent B

Orientation control agent (1)

<Example 1>
On the rubbing-treated surface of a PET (poly-ethylene terephthalate) substrate (manufactured by Toyobo) that has been subjected to a rubbing treatment, the liquid crystal composition 1 is brought to room temperature so that the thickness of the composition layer (coating layer) after drying is 4.5 μm. Was applied using a wire bar. The composition layer was dried at room temperature for 50 seconds and then heated in an atmosphere of 90 ° C. for 1 minute to orient the liquid crystal compound. Then, the composition layer is irradiated with UV (ultraviolet) for 8 seconds at an output of 80% with a fusion D-bulb (lamp 90 mW / cm ² ) at 30 ° C. to fix the reflective layer 1 (cholesteric liquid crystal phase) on the PET substrate. (Corresponding to the layer formed) was formed.
In the above procedure, the liquid crystal compound is oriented at 90 ° C., and then the liquid crystal composition is cooled to 30 ° C., and this treatment changes the spiral-inducing force of the chiral agent contained in the composition layer. Applicable. Rate of change in HTP between the HTP at the orientation temperature (90 ° C.) of the chiral agent in the liquid crystal composition and the HTP at the immobilization temperature (30 ° C.) of the chiral auxiliary in the liquid crystal composition cooled during UV irradiation. Was more than 15%. The HTP change rate is calculated by the following formula (3).
Equation (3): HTP change rate = {(HTP at the immobilization temperature (30 ° C.) of the chiral auxiliary in the liquid crystal composition)-(HTP at the orientation temperature (90 ° C.) of the chiral auxiliary in the liquid crystal composition) / (HTP at the orientation temperature (90 ° C.) of the chiral auxiliary in the liquid crystal composition)} × 100
The viscosity of the components constituting the composition layer at 30 ° C., which is the temperature during the immobilization treatment (“viscosity at the time of solidification” in Table 2), was measured according to the procedure described above.
In addition, the solvent was substantially removed from the composition layer by drying the composition layer at room temperature for 50 seconds.

<Examples 2 to 7, Comparative Example 1>
A reflective layer was formed according to the same procedure as in Example 1 except that the type of liquid crystal composition and the immobilization temperature were changed according to Table 2.
The following evaluation was performed using the obtained reflective layer.

<Orientation observation>
The obtained reflective layer is set in a polarizing microscope, and the reflective layer is set under the condition of epi-illumination (condition of irradiating light from above the reflective layer to observe the reflected light) with an objective lens of 50 times and an eyepiece lens of 10 times. It was observed and evaluated according to the following criteria.
"S": The undulation structure is clearly visible "A": The undulation structure is visible "B": The undulation structure is slightly visible "C": The undulation structure is not visible When the undulation structure is visible , A clear diffraction grating-like pattern can be confirmed.

<30 ° reflection amount>
The reflectance layer was set on a spectrophotometer V-670 (manufactured by JASCO Corporation) equipped with an absolute reflectance measurement system toward the light source, and the reflectance was measured under the detection condition of 0 ° incident 30 °. That is, the incident light is emitted from the light source from the normal direction of the surface of the reflective layer, and the detector having the polar angle θ arranged at 30 ° with respect to the normal direction of the surface of the reflective layer reflects each wavelength at a wavelength of 380 to 800 nm. The rate was measured. From the obtained data (horizontal axis: wavelength, vertical axis: reflectance), the peak area obtained by integrating the peaks of each wavelength was calculated and obtained as a 30 ° reflection amount.
When determining the above-mentioned reflection amount, the 30 ° reflection amount using only the substrate was separately measured and used as a baseline.

In any of Examples 1 to 7, the HTP change rate (%) was 40% or less.

As shown in Table 2 above, according to the production method of the present invention, a reflective layer having excellent diffuse reflectance can be obtained.
In particular, when the viscosity at the time of immobilization was 10000 mPa · s or more (preferably 15000 mPa · s or more), it was confirmed that the undulation structure was formed more clearly and the diffuse reflectance was further improved.

<Example 8>
The following liquid crystal composition 7 was sealed at 90 ° C. in a horizontally oriented cell with ITO having a cell gap of 5 μm in a yellow light environment. Then, the enclosed liquid crystal composition 7 was oriented at 90 ° C. for 1 minute, and then the temperature was lowered to 30 ° C. In this cooling process, since the liquid crystal compound of the liquid crystal composition 7 and the chiral agent were in a predetermined combination, there was almost no change in HTP.
Next, when a voltage of 50 V was applied to the cell, it was confirmed from the orientation observation that an undulation structure was formed in the liquid crystal composition 7. After that, the temperature of the liquid crystal composition 7 was set to 30 ° C., and UV (ultraviolet rays) was irradiated for 8 seconds at an output of 80% with ^{a fusion D-bulb (lamp 90 mW / cm 2) to fix the undulation structure and to form a reflective layer.} Obtained. As a result of observing the orientation of the reflective layer, the undulation structure was confirmed.
Further, the area of the reflection peak (30 ° reflection amount) under the 0 ° incident 30 ° detection condition in the spectrophotometer V-670 was 10.2.
The viscosity of the liquid crystal composition 7 at 30 ° C. was 14100 mPa · s.

The following components were mixed to prepare a liquid crystal composition 7.
Bar-shaped liquid crystal compound 201 90 parts by mass Rod-shaped liquid crystal compound 203 10 parts by mass Polymerization initiator Irg907 (manufactured by BASF) 3 parts by mass Polymerization sensitizer DETX-S (manufactured by Nippon Kayaku Co., Ltd.) 1 part by mass Chiral agent LC-756 (BASF) (Manufactured by the company) 4.5 parts by mass

10 Substrate 12a Layer of composition in cholesteric liquid crystal phase state 12b Reflective layer 14 Bright part 16 Dark part

Claims (6)

A method for producing a reflective layer in which the cholesteric liquid crystal phase is fixed and the bright and dark parts derived from the cholesteric liquid crystal phase observed by a scanning electron microscope in a cross section are wavy.
A composition layer containing a liquid crystal compound having a polymerizable group and a chiral agent is formed, and the bright and dark parts derived from the cholesteric liquid crystal phase observed by a scanning electron microscope in the cross section of the formed composition layer are wavy. Step 1 to carry out the changing process and
The composition layer obtained in the above step 1 is provided with a step 2 of immobilizing the composition layer.
The treatment in step 1 heats the composition layer to orient the liquid crystal compound so that the bright and dark parts derived from the cholesteric liquid crystal phase are parallel to the surface of the composition layer. The liquid crystal phase is formed, and then the composition layer is cooled so that the temperature of the composition layer decreases by 30 ° C. or more so that the spiral inducing force of the chiral agent contained in the composition layer increases by 5% or more. It is a process to do
A method for producing a reflective layer, wherein the viscosity of the composition constituting the composition layer is 2000 mPa · s or more during the immobilization treatment of the step 2. The method for producing a reflective layer according to claim 1, wherein the viscosity is 10,000 mPa · s or more. The method for producing a reflective layer according to claim 1 or 2, wherein the viscosity is 15,000 mPa · s or more. The method for producing a reflective layer according to any one of claims 1 to 3, wherein the immobilization treatment is a light irradiation treatment. The method for producing a reflective layer according to any one of claims 1 to 4 , wherein the liquid crystal compound has a plurality of polymerizable groups. The method for producing a reflective layer according to any one of claims 1 to 5 , wherein the content of the liquid crystal compound in the composition layer is 60% by mass or more.

Images