JP5902641B2 - Optical interference pigment and method for producing the same - Google Patents

Description

  The present invention relates to a light interference pigment and a method for producing the same.

  It is known that a light reflecting film obtained by curing and fixing a cholesteric liquid crystal phase reflects one circularly polarized light in principle and transmits the other light at a selective reflection wavelength. As an application of the light reflecting film in which the cholesteric liquid crystal phase is cured and fixed, it is known that the light reflecting film in which the cholesteric liquid crystal phase is cured and fixed is crushed and the resulting particles are used as light interference particles. It has been. For example, Patent Document 1 discloses that a light-reflecting film in which a cholesteric liquid crystal phase is fixed by being cured by ultraviolet irradiation is classified by pulverizing and sieving it off from a carrier, and sieving. A method is described for producing pigments that act as filters in the -B region. Patent Document 2 describes a method for producing a light protective agent preparation in which a light reflecting film obtained by curing and fixing a cholesteric liquid crystal phase by ultraviolet irradiation is pulverized and mixed with a pigment.

  On the other hand, in a technical field different from the technical field of producing particles having an optical interference effect, a method of producing particles by pulverizing a liquid crystal polymer which is a non-film-like (bulk) polycondensate obtained by polycondensing monomers It has been known. In the technical field of producing such non-film-like (bulk) polycondensate by producing particles that do not exhibit such light interference action, it is known to wash the particles before or after the particles are formed. . For example, Patent Document 3 describes a method for producing a liquid crystal polyester obtained by granulating a polycondensate, and further describes that the particles are washed with an acidic aqueous solution after being granulated, and further washed with water. Patent Document 4 describes a method for producing a flat polyester powder by washing porous polyester before granulation with high-temperature ethylene glycol or hot water, drying it, and then pulverizing it into particles. Yes. In Patent Document 5, the PTFE coarse particles obtained by suspension polymerization of polytetrafluoroethylene (PTFE) are finely pulverized in a wet state and then washed with water (pure water) to efficiently produce a powder for molding PTFE. It describes that the amount of impurities can be reduced.

However, it has not been studied in the past, including Patent Documents 1 and 2, to wash the obtained light interference particles after crushing the light reflecting film in which the cholesteric liquid crystal phase is cured and fixed.
In addition, even before crushing the light reflecting film on which the cholesteric liquid crystal phase is cured and fixed, the film obtained by curing and solidifying the polymerizable liquid crystal compound is still used as a functional film as a member of other products. In the first place, unlike the case where the non-film-like polycondensate is crushed as in Patent Documents 3 to 5, the necessity of removing impurities by washing after film formation is not known, and examples of washing after film formation are also included. Little was known. As an example of cleaning a light reflection film in which a slightly known cholesteric liquid crystal phase is cured and fixed, Patent Document 6 discloses a light reflection film in which a cholesteric liquid crystal phase is cured and fixed. It was only described that it was immersed in a container containing an organic solvent and washed.

JP 2000-044551 A JP 2003-183145 A JP 2003-132512 A JP 2012-001440 A International Publication WO 96/28498 JP 2012-101999 A

When a light interference pigment obtained by crushing a light-reflecting film that has been cured by fixing a polymerizable liquid crystal compound is dispersed in a dispersion medium and used in cosmetics, the residual monomer (polymerizable liquid crystal compound) affects safety. There is a possibility of doing. Furthermore, when the present inventor actually prepared a dispersion liquid in which a light interference pigment is dispersed in a dispersion medium, it has been found that there is a problem that the quality (light reflection performance at a selective reflection wavelength) as the light interference pigment deteriorates. .
In order to avoid this problem, it is conceivable to use a polymer-based material such as a liquid crystal polymer or a polycondensate to form a light reflecting layer in which a cholesteric liquid crystal phase is fixed. In the case of a polymer-based material, It was found that there was a problem that it was difficult to make a pigment.

  The present invention aims to remedy the above problems and to satisfy the demands. That is, the problem to be solved by the present invention is to provide a method for producing a light interference pigment having good light reflection performance at a selective reflection wavelength when dispersed in a dispersion medium.

Under such circumstances, the present inventors diligently studied to solve the above-mentioned problems. As a result, a light-reflective cholesteric liquid crystal film obtained by curing and fixing a polymerizable liquid crystal compound is As a countermeasure against problems peculiar to lamination such as wavelength shift and wavelength shift, there are many uncured monomers and additives in the film to adjust the curing and add additives. In this case, when the pigment is dispersed in the dispersion medium, these uncured monomers and additives are expected to elute and adversely affect various performances. For this reason, we considered washing with a solvent in advance, but if the solubility was too low, the washing was insufficient, while if the solubility was too high, a new problem that some of the cured monomers would dissolve and degrade performance I found out that
In particular, cholesteric liquid crystals also have the problem that the optical characteristics at the selective reflection wavelength are further deteriorated (the selective reflection wavelength is shifted and the light reflectance is lowered). The main factor is that the film having a cholesteric liquid crystal structure is used as an optical interference pigment. As a result of the solvent penetration into the light interference pigment (which occurs simultaneously with the elution of the residual monomer), the free volume (space) of the liquid crystal structure of the light interference pigment widens, and as a result, the gap between the light interference pigments It was found that Δn (refractive index) of the light interference pigment was lowered by the surrounding material (for example, resin) entering the dispersion medium.

  Therefore, as a result of the present inventors diligently studying to solve the above problems and problems, particles obtained by pulverizing a film having a cholesteric liquid crystal structure produced by fixing and fixing the alignment state of the polymerizable liquid crystal compound By using a solvent having a specific SP value and washing at a specific temperature, it was found that the light reflection performance at the selective reflection wavelength when dispersed in a dispersion medium was improved, and the present invention was achieved.

The present invention, which is means for solving the above problems, is as follows.
[1] A step of producing a film having a cholesteric liquid crystal structure in which the alignment state of the polymerizable liquid crystal compound is cured and fixed;
Crushing the film having the cholesteric liquid crystal structure to produce light interference particles;
Washing the light interference particles with an organic solvent having an SP value of 8.5 to 12 (cal / cm ³ ) ^1/2 at a temperature of 35 ° C. or higher;
(SP value represents the solubility parameter δ measured by the Hoy method, and is represented by the following formula (1)).
δ = (ΔE / V) ^1/2 formula (1)
(In formula (1), V represents the molar molecular volume of the solvent, and ΔE represents the cohesive energy (evaporation energy).)
[2] The method for producing an optical interference pigment according to [1] reflects right circularly polarized light obtained by fixing the film having the cholesteric liquid crystal structure by fixing the alignment state of at least one polymerizable liquid crystal compound. It is preferable to manufacture the light reflecting layer by laminating a light reflecting layer that reflects left circularly polarized light obtained by curing and fixing the alignment state of at least one polymerizable liquid crystal compound.
[3] The method for producing a light interference pigment according to [1] or [2] is preferably performed by immersing the light interference particles in the organic solvent for cleaning.
[4] The method for producing a light interference pigment according to any one of [1] to [3] is a residue obtained by immersing and cleaning the light interference particles in the organic solvent and then filtering the organic solvent through a filter. It is preferable to fractionate.
[5] In the method for producing a light interference pigment according to [4], the filtration accuracy of the filter used for filtration of the organic solvent is preferably 0.3 to 6 μm.
[6] In the method for producing a light interference pigment according to any one of [1] to [5], the washing temperature is preferably 40 ° C. or higher and the boiling point of the organic solvent or lower.
[7] In the method for producing a light interference pigment according to any one of [1] to [6], the light interference particles preferably have a flat plate shape.
[8] In the method for producing a light interference pigment according to any one of [1] to [7], the selective reflection wavelength of the light interference pigment is preferably 420 nm or less.
[9] In the method for producing a light interference pigment according to any one of [1] to [8], the thickness of the light interference particles is preferably 4 to 10 μm.
[10] In the method for producing a light interference pigment according to any one of [1] to [9], the average equivalent circle diameter is 100 μm or less using a filter after crushing the film having the cholesteric liquid crystal structure. It is preferable to sort out the light interference particles.
[11] The method for producing an optical interference pigment according to any one of [1] to [10], wherein a coating liquid containing the polymerizable liquid crystal compound is applied on a substrate to produce a film having the cholesteric liquid crystal structure. To do.
[12] In the method for producing a light interference pigment according to [11], the substrate is preferably a plastic film having a glass transition temperature of 150 ° C. or lower.
[13] In the method for producing a light interference pigment according to any one of [1] to [12], the alignment state of the polymerizable liquid crystal compound is changed with respect to the composition containing the polymerizable liquid crystal compound and a photopolymerization initiator. It is preferably fixed by a curing reaction that proceeds by irradiation with ultraviolet rays.
[14] In the method for producing a light interference pigment according to any one of [1] to [13], the polymerizable liquid crystal compound is preferably a compound represented by the following general formula (X).
Formula ^{(X) Q 1 -L 1 -Cy} 1 -L 2 - (Cy 2 -L 3) n -Cy 3 -L 4 -Q 2
(In General Formula (X), Q ¹ and Q ² are each independently a polymerizable group, L ¹ and L ⁴ are each independently a divalent linking group, and L ² and L ³ are each independently a single group. A bond or a divalent linking group, Cy ¹ , Cy ² and Cy ³ are divalent cyclic groups, and n is 0, 1, 2, or 3.)
[15] A light interference pigment produced by the method for producing a light interference pigment according to any one of [1] to [14].

ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the light interference pigment which has the favorable light reflection performance in the selective reflection wavelength when it makes it disperse | distribute to a dispersion medium can be provided.
can do.

FIG. 1 is a schematic view showing a cross section of an example of a film having a cholesteric liquid crystal structure, which is used when manufacturing optical interference particles used for manufacturing the optical interference pigment of the present invention.

Hereinafter, the present invention will be described in detail.
The description of the constituent elements described below may be made based on typical embodiments and specific examples of the present invention, but the present invention is not limited to such embodiments and specific examples. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
In the present specification, the solid containing the polymerizable liquid crystal compound may be composed of a crystal of the polymerizable liquid crystal compound or may be an amorphous form that is not a crystal. Moreover, other components, such as a polymerization initiator and a chiral agent, may also be included. In some cases, all or some of these may be mixed.
In the present specification, the SP value represents the solubility parameter value δ calculated by the Hoy method, and is defined by the square root of the cohesive energy density represented by the following formula (1).
δ = (ΔE / V) ^1/2 formula (1)
(In formula (1), V represents the molar molecular volume of the solvent, and ΔE represents the cohesive energy (evaporation energy).)
The SP value (δ) is calculated according to J. Hildebrand, R. Scott: “The Solubility of Non-electrolytes”, 3rd Ed. , P.119-133, Reinhold Publishing Corp. (1949).
The Hoy method represents the content described in “Polymer Handbook (4th. Edition)”.

[Method for producing optical interference pigment]
The method for producing a light interference pigment of the present invention comprises a step of producing a film having a cholesteric liquid crystal structure in which an alignment state of a polymerizable liquid crystal compound is cured and fixed, and crushing the film having the cholesteric liquid crystal structure to produce light interference particles. And a step of washing the light interference particles at a temperature of 35 ° C. or higher using an organic solvent having an SP value of 8.5 to 12 (cal / cm ³ ) ^1/2 at least. (SP value represents the solubility parameter δ measured by the Hoy method and is represented by the following formula (1)).
δ = (ΔE / V) ^1/2 formula (1)
(In formula (1), V represents the molar molecular volume of the solvent, and ΔE represents the cohesive energy (evaporation energy).)
With such a configuration, it is possible to produce an optical interference pigment that has good light reflection performance at a selective reflection wavelength when dispersed in a dispersion medium.
Here, “the light reflection performance at the selective reflection wavelength is good” when the light interference pigment is dispersed in the dispersion medium means that 1 g of the dried light interference pigment is mixed with 10 g of acrylic silicone and 0.5 g of ethanol. It is applied to a PMMA plate with a thickness of 100 μm, and the applied plate means that the reflectance is 1% or more at the selective reflection wavelength, and the reflectance is more preferably 3% or more, more preferably 10%. The above is particularly preferable. This measured value is a value when the optical performance of a film coated with a thin dispersion liquid containing a light interference pigment and a dispersion medium is measured, and is substantially the value of the dispersion liquid containing the light interference pigment and the dispersion medium. It is equal to the optical performance.
Hereinafter, materials used in the method for producing a light interference pigment of the present invention and preferred production conditions will be described.

(1) Production of Film Having Cholesteric Liquid Crystal Structure The method for producing a light interference pigment of the present invention includes a step of producing a film having a cholesteric liquid crystal structure in which the alignment state of the polymerizable liquid crystal compound is cured and fixed. The method for forming the film having the cholesteric liquid crystal structure is not particularly limited. For example, a liquid containing a cholesteric liquid crystal material is applied on a substrate, the solvent is evaporated, and then the liquid crystal is aligned by heating. And a method of producing by repeating the step of irradiating with ultraviolet rays once or a plurality of times is preferable.
Details of a method for manufacturing a film having a cholesteric liquid crystal structure will be described below.

  The film having the cholesteric liquid crystal structure is formed by forming an alignment film on the substrate as necessary, and coating, drying, aligning and fixing a cholesteric liquid crystal composition coating solution containing a solvent described later on the surface thereof. . The coating can be performed by a known method (for example, a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, or a die coating method) using a cholesteric liquid crystal composition coating solution. Alternatively, it may be formed by discharging using an inkjet apparatus.

There is no restriction | limiting in particular as said board | substrate, Glass or a plastic film, a metal, etc. can be used suitably. Among them, in the method for producing a light interference pigment of the present invention, it is preferable to use a plastic film as the substrate, and to use a plastic film having a glass transition temperature of 170 ° C. or less reduces the production cost by using a resin having low heat resistance. It is preferable from the viewpoint that can be performed. The glass transition temperature of the plastic film used as the substrate is more preferably 40 to 160 ° C, and particularly preferably 60 to 150 ° C.
It is preferable to use PET as the substrate.

  The state of “fixed” is the most typical and preferred mode in which the orientation of the liquid crystal compound contained in the film having a cholesteric liquid crystal structure is maintained, but is not limited thereto, specifically, Usually, the film having the cholesteric liquid crystal structure is not fluid in the temperature range of 0 ° C. to 50 ° C., and under the severer conditions of −30 ° C. to 70 ° C., and the orientation form is changed by an external field or an external force. This means a state in which the fixed alignment form can be kept stable without causing the fixing.

  As a method for fixing the alignment state in the present invention, the liquid containing the polymerizable liquid crystal compound (hereinafter also referred to as a liquid crystal composition) is once heated to the liquid crystal phase formation temperature, and then the alignment state is maintained. By cooling, it can be formed by fixing without impairing the alignment form in the liquid crystal state. Further, the liquid crystal composition to which the polymerization initiator is added can be heated to the liquid crystal phase formation temperature and aligned, and then polymerized to fix the alignment state of the liquid crystal state. The latter polymerization reaction is preferably performed, and the photopolymerization reaction is more preferably performed using a photopolymerization initiator. In the present invention, when the film having the cholesteric liquid crystal structure is finally formed, the liquid crystal compound is no longer required to be liquid crystalline as long as the optical properties are maintained. For example, a low-molecular liquid crystal compound may have a group that reacts with heat, light, or the like, and as a result, it may be polymerized or cross-linked by reaction with heat, light, or the like to increase the molecular weight and lose liquid crystallinity.

  The liquid crystal composition is preferably obtained by mixing a polymerizable liquid crystal compound, an optically active compound (synonymous with a chiral agent and a chiral agent in the present invention), a polymerization initiator, and a solvent. The polymerizable liquid crystal compounds may be used alone or in combination. The liquid crystal composition may contain a non-polymerizable liquid crystal compound as long as it contains the polymerizable liquid crystal compound. For example, a polymerizable liquid crystal compound and a non-polymerizable liquid crystal compound can be used in combination. Further, a low molecular weight polymerizable liquid crystal compound and a polymer liquid crystal compound can be used in combination. The liquid crystal composition may further contain a horizontal alignment agent, a non-uniformity inhibitor, a repellency inhibitor, a polymerizable monomer and the like in order to improve alignment uniformity, coating suitability, and film strength. If necessary, the liquid crystal composition may further contain a polymerization inhibitor, an antioxidant, an ultraviolet absorber, a light stabilizer and the like as long as optical performance is not deteriorated.

  The liquid crystal temperature range of the liquid crystal composition is preferably in the range of 10 to 250 ° C., more preferably in the range of 10 to 150 ° C. from the viewpoint of production suitability and the like. When the temperature is lower than 10 ° C., a cooling step or the like may be required to lower the temperature to a temperature range exhibiting a cholesteric liquid crystal phase. When the temperature exceeds 200 ° C., a high temperature is required to make the isotropic liquid state higher than the temperature range once exhibiting a cholesteric liquid crystal phase, which is disadvantageous from waste of heat energy, deformation of the substrate, and alteration.

-Polymerizable liquid crystal compound-
As the polymerizable liquid crystal compound, a polymerizable rod-like liquid crystal compound is preferable.
Polymerizable rod-shaped liquid crystal compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines. , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.
More preferably, the orientation of the polymerizable rod-like liquid crystal compound is fixed by polymerization, and the rod-like liquid crystal compound is more preferably a polymerizable rod-like nematic liquid crystal compound.
Examples of the polymerizable rod-like liquid crystal compound include Makromol. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), U.S. Pat. Nos. 4,683,327, 5,622,648 and 5,770,107, WO 95/22586, 95/24455, 97/97. No. 0600, No. 98/23580, No. 98/52905, JP-A-1-272551, JP-A-6-16616, JP-A-7-110469, JP-A-11-80081, and Japanese Patent Application No. 2001-64627 These compounds can be used.
In the method for producing a light interference pigment of the present invention, the polymerizable liquid crystal compound is preferably a compound represented by the following general formula (X).
Formula ^{(X) Q 1 -L 1 -Cy} 1 -L 2 - (Cy 2 -L 3) n -Cy 3 -L 4 -Q 2
(In General Formula (X), Q ¹ and Q ² are each independently a polymerizable group, L ¹ and L ⁴ are each independently a divalent linking group, and L ² and L ³ are each independently a single group. A bond or a divalent linking group, Cy ¹ , Cy ² and Cy ³ are divalent cyclic groups, and n is 0, 1, 2, or 3.)

The compound (polymerizable rod-like liquid crystal compound) represented by the general formula (X) will be further described below.
In the general formula (X), Q ¹ and Q ² are each independently a polymerizable group. The polymerization reaction of the polymerizable group is preferably addition polymerization (including ring-opening polymerization) or condensation polymerization. In other words, the polymerizable group is preferably a functional group capable of addition polymerization reaction or condensation polymerization reaction. Examples of polymerizable groups are shown below.

In the general formula (X), L ¹ and L ⁴ are each independently a divalent linking group. L ¹ and L ⁴ each independently include —O—, —S—, —CO—, —NR—, —C═N—, a divalent chain group, a divalent cyclic group, and combinations thereof. A divalent linking group selected from the group is preferred. R is an alkyl group having 1 to 7 carbon atoms or a hydrogen atom.
The example of the bivalent coupling group which consists of a combination is shown below. Here, the left side is coupled to Q (Q ¹ or Q ² ), and the right side is coupled to Cy (Cy ¹ or Cy ³ ).
L-1: —CO—O—divalent chain group —O—
L-2: -CO-O-divalent chain group -O-CO-
L-3: —CO—O—divalent chain group —O—CO—O—
L-4: -CO-O-divalent chain group -O-divalent cyclic group-
L-5: -CO-O-divalent chain group -O-divalent cyclic group -CO-O-
L-6: -CO-O-divalent chain group -O-divalent cyclic group -O-CO-
L-7: -CO-O-divalent chain group-O-divalent cyclic group-divalent chain group-
L-8: -CO-O-divalent chain group -O-divalent cyclic group -divalent chain group -CO-O-
L-9: -CO-O-divalent chain group -O-divalent cyclic group -divalent chain group -O-CO-
L-10: —CO—O—divalent chain group—O—CO—divalent cyclic group—
L-11: -CO-O-divalent chain group -O-CO-divalent cyclic group -CO-O-
L-12: -CO-O-divalent chain group -O-CO-divalent cyclic group -O-CO-
L-13: —CO—O—Divalent chain group—O—CO—Divalent cyclic group—Divalent chain group—
L-14: -CO-O-divalent chain group -O-CO-divalent cyclic group -divalent chain group -CO-O-
L-15: -CO-O-divalent chain group-O-CO-divalent cyclic group-divalent chain group-O-CO-
L-16: —CO—O—divalent chain group—O—CO—O—divalent cyclic group—
L-17: -CO-O-divalent chain group -O-CO-O-divalent cyclic group -CO-O-
L-18: -CO-O-divalent chain group -O-CO-O-divalent cyclic group -O-CO-
L-19: —CO—O—Divalent chain group—O—CO—O—Divalent cyclic group—Divalent chain group—
L-20: -CO-O-divalent chain group -O-CO-O-divalent cyclic group -divalent chain group -CO-O-
L-21: -CO-O-divalent chain group -O-CO-O-divalent cyclic group -divalent chain group -O-CO-
The divalent chain group means an alkylene group, a substituted alkylene group, an alkenylene group, a substituted alkenylene group, an alkynylene group, or a substituted alkynylene group. An alkylene group, a substituted alkylene group, an alkenylene group and a substituted alkenylene group are preferred, and an alkylene group and an alkenylene group are more preferred.
The alkylene group may have a branch. The alkylene group preferably has 1 to 12 carbon atoms, more preferably 2 to 10 carbon atoms, and most preferably 2 to 8 carbon atoms.
The alkylene part of the substituted alkylene group is the same as the above alkylene group. Examples of the substituent include a halogen atom.
The alkenylene group may have a branch. The alkenylene group preferably has 2 to 12 carbon atoms, more preferably 2 to 10 carbon atoms, and most preferably 2 to 8 carbon atoms.
The alkylene part of the substituted alkylene group is the same as the above alkylene group. Examples of the substituent include a halogen atom.
The alkynylene group may have a branch. The alkynylene group preferably has 2 to 12 carbon atoms, more preferably 2 to 10 carbon atoms, and most preferably 2 to 8 carbon atoms.
The alkynylene part of the substituted alkynylene group is the same as the above alkynylene group. Examples of the substituent include a halogen atom.
Specific examples of the divalent chain group include ethylene, trimethylene, propylene, tetramethylene, 2-methyl-tetramethylene, pentamethylene, hexamethylene, octamethylene, 2-butenylene, 2-butynylene and the like.
The definition and examples of the divalent cyclic group are the same as those of Cy ¹ , Cy ² and Cy ³ described later.

In the general formula (X), R ² is preferably an alkyl group having 1 to 4 carbon atoms or a hydrogen atom, more preferably a methyl group, an ethyl group or a hydrogen atom, and a hydrogen atom. Is most preferred.

In the general formula (X), L ^{2 and} L ³ are each independently a single bond or a divalent linking group. L ² and L ³ each independently include —O—, —S—, —CO—, —NR—, —C═N—, a divalent chain group, a divalent cyclic group, and combinations thereof. It is preferably a divalent linking group or a single bond selected from the group. R is an alkyl group having 1 to 7 carbon atoms or a hydrogen atom, preferably an alkyl group having 1 to 4 carbon atoms or a hydrogen atom, more preferably a methyl group, an ethyl group or a hydrogen atom. Preferably, it is a hydrogen atom. The divalent chain group and the divalent cyclic group have the same definitions as L ¹ and L ⁴ .
Preferred divalent linking groups as L ² or L ³ include —COO—, —OCO—, —OCOO—, —OCONR—, —COS—, —SCO—, —CONR—, —NRCO—, —CH _2. CH _2- , -C = C-COO-, -C = N-, -C = N-N = C-, and the like.

In the general formula (X), n is 0, 1, 2, or 3. When n is 2 or 3, two L ³ may be the same or different, and two Cy ² may be the same or different. n is preferably 1 or 2, and more preferably 1.

In the general formula (X), Cy ¹ , Cy ² and Cy ³ are each independently a divalent cyclic group.
The ring contained in the cyclic group is preferably a 5-membered ring, a 6-membered ring, or a 7-membered ring, more preferably a 5-membered ring or a 6-membered ring, and most preferably a 6-membered ring.
The ring contained in the cyclic group may be a condensed ring. However, it is more preferably a monocycle than a condensed ring.
The ring contained in the cyclic group may be any of an aromatic ring, an aliphatic ring, and a heterocyclic ring. Examples of the aromatic ring include a benzene ring and a naphthalene ring. Examples of the aliphatic ring include a cyclohexane ring. Examples of the heterocyclic ring include a pyridine ring and a pyrimidine ring.
As the cyclic group having a benzene ring, 1,4-phenylene is preferable. As the cyclic group having a naphthalene ring, naphthalene-1,5-diyl and naphthalene-2,6-diyl are preferable. The cyclic group having a cyclohexane ring is preferably 1,4-cyclohexylene. As the cyclic group having a pyridine ring, pyridine-2,5-diyl is preferable. The cyclic group having a pyrimidine ring is preferably pyrimidine-2,5-diyl.
The cyclic group may have a substituent. Examples of the substituent include a halogen atom, a cyano group, a nitro group, an alkyl group having 1 to 5 carbon atoms, a halogen-substituted alkyl group having 1 to 5 carbon atoms, and an alkoxy group having 1 to 5 carbon atoms. An alkylthio group having 1 to 5 carbon atoms, an acyloxy group having 2 to 6 carbon atoms, an alkoxycarbonyl group having 2 to 6 carbon atoms, a carbamoyl group, and an alkyl-substituted carbamoyl group having 2 to 6 carbon atoms And an acylamino group having 2 to 6 carbon atoms.

  Examples of the polymerizable liquid crystal compound represented by the general formula (X) are shown below. The present invention is not limited to these.

Further, as the rod-like liquid crystal compound, in addition to the polymerizable rod-like liquid crystal compound represented by the general formula (X), at least one compound represented by the following general formula (V) may be mixed.
Formula ^{(V) M 1 - (L} 1) p -Cy 1 -L 2 - (Cy 2 -L 3) n -Cy 3 - (L 4) q -M 2
In the formula, M ¹ and M ² each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a heterocyclic group, a cyano group, a halogen, —SCN, —CF ₃ , It represents a nitro group or Q ¹ , but at least one of M ¹ and M ² represents a group other than Q ¹ .
^{However, Q 1, L 1, L} 2, L 3, L 4, Cy 1, Cy 2, Cy 3 and n have the same meanings as the group represented by the general formula (X). P and q are 0 or 1.
When M ¹ and M ² do not represent Q ¹ , they are preferably a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, or a cyano group, more preferably a carbon number It is preferably an alkyl group of 1 to 4 or a phenyl group, and p and q are preferably 0.

Moreover, as a preferable mixing ratio of the compound represented by the general formula (V) in the mixture of the polymerizable liquid crystal compound represented by the general formula (X) and the compound represented by the general formula (V), 0.1% to 40%, more preferably 1% to 30%, and still more preferably 5% to 20%.
Although the preferable example of a compound represented by the said general formula (V) is shown below, this invention is not limited to these.

-Optically active compound-
As the optically active compound, a known chiral agent (for example, liquid crystal device handbook, Chapter 3-4-3, TN, chiral agent for STN, 199 pages, edited by Japan Society for the Promotion of Science, 142nd Committee, 1989) is used. be able to. The optically active compound generally contains an asymmetric carbon atom, but an axially asymmetric compound or a planar asymmetric compound that does not contain an asymmetric carbon atom can also be used as a chiral agent. Examples of the axial asymmetric compound or the planar asymmetric compound include binaphthyl, helicene, paracyclophane, and derivatives thereof. The optically active compound (chiral agent) may have a polymerizable group. When the optically active compound has a polymerizable group, a polymer having a rod-like nematic liquid crystalline repeating unit and an optically active structure can be formed by a polymerization reaction of the polymerizable rod-like nematic liquid crystalline compound. The polymerizable group of the optically active compound is preferably the same group as the polymerizable group of the polymerizable rod-like nematic liquid crystalline compound. Accordingly, the polymerizable group of the optically active compound is also preferably an unsaturated polymerizable group, an epoxy group or an aziridinyl group, more preferably an unsaturated polymerizable group, and an ethylenically unsaturated polymerizable group. Is most preferred.
A commercially available chiral agent may be used as the chiral agent, and LC-756 (manufactured by BASF) can be preferably used when forming a light reflection layer that reflects right circularly polarized light.
Moreover, the chiral agent may have liquid crystallinity.

  It is preferable that the usage-amount of a chiral agent is 1-30 mol% of the quantity of the said polymeric liquid crystal compound. A smaller amount of chiral agent is preferred because it often does not affect liquid crystallinity. Therefore, it is preferable that the chiral agent has a strong twisting force. As such a chiral agent having a strong twisting force, for example, the chiral agents described in JP-A No. 2003-287623 and Japanese Patent No. 4287599 can be used.

-Polymerization initiator-
The film-forming liquid crystal composition having a cholesteric liquid crystal structure is preferably a curable composition, and for that purpose, it preferably contains a polymerization initiator. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator, a photopolymerization reaction using a photopolymerization initiator, and a polymerization reaction by electron beam irradiation. To prevent the substrate from being deformed or altered by heat, The polymerization reaction by photopolymerization reaction and electron beam irradiation is preferred. That is, the method for producing a light interference pigment according to the present invention includes a curing reaction that proceeds by irradiating the composition containing the polymerizable liquid crystal compound and the photopolymerization initiator with ultraviolet rays with respect to the alignment state of the polymerizable liquid crystal compound. It is preferable to fix.

  Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatics. Group acyloin compounds (described in US Pat. No. 2,722,512), polynuclear quinone compounds (described in US Pat. Nos. 3,046,127 and 2,951,758), combinations of triarylimidazole dimers and p-aminophenyl ketone (US patents) No. 3549367), acridine and phenazine compounds (JP-A-60-105667, US Pat. No. 4,239,850), oxadiazole compounds (US Pat. No. 4,221,970), and the like. .

The amount of the photopolymerization initiator used is preferably 0.1 to 20% by mass, more preferably 1 to 8% by mass, based on the liquid crystal composition (solid content in the case of a coating liquid).
Light irradiation for the polymerization of the liquid crystal compound is preferably performed using ultraviolet rays. Irradiation energy is preferably ^{10mJ / cm 2 ~50J / cm 2} , further preferably ^{50mJ / cm 2 ~800mJ / cm 2} . In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.
Further, since the oxygen concentration in the atmosphere is related to the degree of polymerization, when the desired degree of polymerization is not reached in the air, it is preferable to reduce the oxygen concentration by a method such as nitrogen substitution. A preferable oxygen concentration is preferably 10% or less, more preferably 7% or less, and most preferably 3% or less.

  The polymerization reaction rate is preferably 70% or more from the viewpoint of maintaining the mechanical strength of the film having the cholesteric liquid crystal structure and suppressing the unreacted material from flowing out to the liquid crystal layer or the like, and is preferably 80% or more. More preferably, it is more preferably 90% or more. In order to improve the polymerization reaction rate, a method of increasing the irradiation amount of ultraviolet rays to be irradiated and polymerization under a nitrogen atmosphere or heating conditions are effective. Moreover, after superposing | polymerizing once, the method of hold | maintaining at a temperature higher than superposition | polymerization temperature, and pushing a reaction further by thermal polymerization reaction, and the method of irradiating an ultraviolet-ray again can also be used. The polymerization reaction rate can be measured by comparing the absorption intensity of the infrared vibration spectrum of the polymerization reactive bonding group before and after the polymerization.

-Orientation control agent-
In the liquid crystal composition, compounds described in [0012] to [0030] of JP2012-211306, fluorine-containing (meth) acrylate, or [0037] to [0044] of JP2012-101999A. By containing at least one of the compounds described, it is preferable to reduce the tilt angle of the molecules of the liquid crystal compound at the air interface or to substantially horizontally align it. In this specification, “horizontal alignment” means that the major axis of the liquid crystal molecule is parallel to the film surface, but it is not required to be strictly parallel. An orientation with an inclination angle of less than 20 degrees is meant. When the liquid crystal compound is horizontally aligned in the vicinity of the air interface, since alignment defects are less likely to occur, the transparency in a region other than the selective reflection wavelength is increased, and the reflectance in the selective reflection wavelength region is increased. On the other hand, when the tilt angle of the liquid crystal compound is large, the cholesteric helical axis is deviated from the normal of the film surface, so that the reflectivity is reduced, a fingerprint pattern is generated, and haze is increased or diffraction is exhibited. Therefore, it is not preferable.
Examples of the fluorine-containing (meth) acrylate-based polymer that can be used as an orientation control agent are described in JP-A No. 2007-272185, [0018] to [0043].
As the alignment control agent used in the present invention, the compounds described in Japanese Patent Application No. 2003-331269 (Japanese Patent Application Laid-Open No. 2005-099258) can be used, and the synthesis method of these compounds is also described in the specification. ing.

Furthermore, it is preferable to use a combination of two or more types of alignment control agents, more preferably to use a combination of two or more types of fluorine-based alignment control agents, and the following first alignment control agent and second alignment control. It is particularly preferable to use a combination of agents.
(1) First alignment control agent As the first alignment control agent, a compound having at least one perfluoroalkyl chain can be exemplified.
The first orientation control agent preferably has an embossing ratio represented by the following formula (1) of 50% or less.
Formula (1)
Raising rate (%) = 100% × B / A
(In the formula (1), a lower layer curable liquid crystal composition containing polymerizable liquid crystal molecules and an alignment control agent is fixed by curing in the state of a cholesteric liquid crystal phase to form a lower layer, and alignment control is performed on the lower layer. When the upper layer is laminated by applying the upper layer curable liquid crystal composition having the same composition as the lower layer curable liquid crystal composition except for the agent, and fixing by curing in the state of the cholesteric liquid crystal phase, A is Expresses the fluorine atom content relative to the total amount of carbon atoms and fluorine atoms present on the surface of the lower layer, that is, one-layer product, and B represents the fluorine atom content relative to the total amount of carbon atoms and fluorine atoms present on the surface of the upper layer, ie, the two-layer product. Represents the rate.)

The measurement method for the fluorine atom content relative to the total amount of carbon atoms and fluorine atoms present on the surface of each layer used when measuring the protrusion ratio of the alignment control agent is not limited.
In the present invention, fluorine atoms / carbon atoms (F / C) existing on the surface of each layer were measured by X-ray photoelectron spectroscopy, and the calculation was performed based on these values.

It is preferable that the first alignment control agent is non-polymerizable.
It is preferable that the first alignment control agent has at least two perfluoroalkyl chains, and it is more preferable that the first alignment control agent has two perfluoroalkyl chains.

  The first alignment control agent is preferably contained in an amount of 0.03% by mass or more, more preferably 0.10% by mass or more, based on the polymerizable liquid crystal compound in the liquid crystal composition.

The first alignment control agent is preferably represented by the following general formula (II).
The compound of the following formula (II) is characterized by having a divalent group at the center and a fluorinated alkyl group at the terminal. A compound having a fluorinated alkyl group at the terminal is effective as an alignment accelerator, but conventionally known alignment control agents have a limited use concentration range and a low solubility, limiting their use. It had been. Since the compound of the following formula (II) exhibits equivalent or better orientation performance in a wider concentration range and good solubility, a composition containing them has an advantage that it is easy to use in production.

In the general formula (I), L ¹ , L ² , L ³ , L ⁴ , L ⁵ and L ⁶ are each independently a single bond, —O—, —S—, —CO—, —COO—, —OCO. -, -COS-, -SCO-, -NRCO-, -CONR- (R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms), more preferably -O-, -S-, -CO-. , -COO-, -OCO-, -COS-, -SCO-, more preferably -O-, -CO-, -COO-, -OCO-. The alkyl group that R can take may be linear or branched. As for carbon number, it is more preferable that it is 1-3, and a methyl group, an ethyl group, and n-propyl group can be illustrated.

  Sp represents a single bond or an alkylene group having 1 to 10 carbon atoms, more preferably a single bond or an alkylene group having 1 to 7 carbon atoms, still more preferably a single bond or an alkylene group having 1 to 4 carbon atoms, Non-adjacent methylene groups in the alkylene are substituted with —O—, —S—, —CO—, —COO—, —OCO—, —COS—, —SCO—, —NRCO—, —CONR—, —OH. It may be. The alkylene group may or may not be branched, but a linear alkylene group having no branch is preferred.

A ¹ and A ^{2 each} represent a divalent aromatic hydrocarbon group or a divalent heterocyclic group, and more preferably a divalent aromatic hydrocarbon. The divalent aromatic hydrocarbon group preferably has 6 to 22 carbon atoms, more preferably 6 to 14 carbon atoms, still more preferably 6 to 10 carbon atoms, and still more preferably a phenylene group. . In the case of a phenylene group, it is preferable to have a bond at the meta or para position, and it is particularly preferable to have a bond at the para position. The divalent heterocyclic group preferably has a 5-membered, 6-membered or 7-membered heterocyclic ring. A 5-membered ring or a 6-membered ring is more preferable, and a 6-membered ring is most preferable. As the hetero atom constituting the heterocyclic ring, a nitrogen atom, an oxygen atom and a sulfur atom are preferable. The heterocycle is preferably an aromatic heterocycle. The aromatic heterocycle is generally an unsaturated heterocycle. An unsaturated heterocyclic ring having the most double bond is more preferable. Examples of heterocyclic rings include furan ring, thiophene ring, pyrrole ring, pyrroline ring, pyrrolidine ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, imidazoline ring, imidazolidine ring, pyrazole ring, pyrazoline Ring, pyrazolidine ring, triazole ring, triazane ring, tetrazole ring, pyran ring, thiyne ring, pyridine ring, piperidine ring, oxazine ring, morpholine ring, thiazine ring, pyridazine ring, pyrimidine ring, pyrazine ring, piperazine ring and triazine ring included. The divalent aromatic hydrocarbon group or divalent heterocyclic group represented by A ¹ and A ² may have a substituent. Examples of such a substituent include an alkyl group having 1 to 8 carbon atoms, an alkoxy group, a halogen atom, a cyano group, or an ester group. For the explanation and preferred ranges of these groups, the corresponding description of T below can be referred to. Examples of the substituent for the divalent aromatic hydrocarbon group or divalent heterocyclic group represented by A ¹ or A ² include a methyl group, an ethyl group, a methoxy group, an ethoxy group, a bromine atom, a chlorine atom, and a cyano group. Examples include groups. A ¹ and A ² are preferably the same.

で表される二価の基または二価の芳香族複素環基を表す（Ｘは炭素数１〜８のアルキル基、アルコキシ基、ハロゲン原子、シアノ基またはエステル基を表し、Ｙａ、Ｙｂ、Ｙｃ、Ｙｄはおのおの独立して水素原子または炭素数１〜４のアルキル基を表す）であり、より好ましくは

であり、さらに好ましくは

である。Ｘがとりうるアルキル基の炭素数は１〜８であり、１〜５であることが好ましく、１〜３であることがより好ましい。アルキル基は、直鎖状、分枝状、環状のいずれであってもよく、直鎖状または分枝状であることが好ましい。好ましいアルキル基として、メチル基、エチル基、ｎ−プロピル基、イソプロピル基などを例示することができる。Ｘがとりうるアルコキシ基のアルキル部分については、Ｘがとりうるアルキル基の説明と好ましい範囲を参照することができる。Ｘがとりうるハロゲン原子としては、フッ素原子、塩素原子、臭素原子、ヨウ素原子を挙げることができ、塩素原子、臭素原子が好ましい。Ｘがとりうるエステル基としては、ＲＣＯＯ−で表される基を例示することができる。Ｒとしては炭素数１〜８のアルキル基を挙げることができる。Ｒがとりうるアルキル基の説明と好ましい範囲については、上記のＸがとりうるアルキル基の説明と好ましい範囲を参照することができる。エステルの具体例として、ＣＨ₃ＣＯＯ−、Ｃ₂Ｈ₅ＣＯＯ−を挙げることができる。Ｙａ、Ｙｂ、Ｙｃ、Ｙｄがとりうる炭素数１〜４のアルキル基は、直鎖状であっても分枝状であってもよい。例えば、メチル基、エチル基、ｎ−プロピル基、イソプロピル基などを例示することができる。二価の芳香族複素環基の説明と好ましい範囲については、下記のＡ¹とＡ²の芳香族複素環基に関する説明と記載を参照することができる。 T is

(X represents an alkyl group having 1 to 8 carbon atoms, an alkoxy group, a halogen atom, a cyano group, or an ester group, Ya, Yb, Yc. , Yd each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and more preferably

And more preferably

It is. Carbon number of the alkyl group which X can take is 1-8, it is preferable that it is 1-5, and it is more preferable that it is 1-3. The alkyl group may be linear, branched or cyclic, and is preferably linear or branched. Preferred examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. For the alkyl part of the alkoxy group that X can take, the description and preferred range of the alkyl group that X can take can be referred to. Examples of the halogen atom that X can take include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a chlorine atom and a bromine atom are preferable. Examples of the ester group that X can take include a group represented by RCOO-. Examples of R include an alkyl group having 1 to 8 carbon atoms. For the description and preferred range of the alkyl group that R can take, the description and preferred range of the alkyl group that X can take can be referred to. Specific examples of the ester include CH ₃ COO— and C ₂ H ₅ COO—. The alkyl group having 1 to 4 carbon atoms that can be taken by Ya, Yb, Yc, and Yd may be linear or branched. For example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group and the like can be exemplified. For the explanation and preferred range of the divalent aromatic heterocyclic group, the following explanation and description regarding the aromatic heterocyclic group of A ¹ and A ² can be referred to.

Hb represents a fluorinated alkyl group having 3 to 30 carbon atoms, more preferably a fluorinated alkyl group having 3 to 20 carbon atoms, and further preferably a fluorinated alkyl group having 3 to 10 carbon atoms. Here, the fluorinated alkyl group may or may not be substituted with hydrogen. The fluorinated alkyl group may be linear, branched or cyclic, but is preferably linear or branched, and more preferably linear. Preferred examples of the fluorinated alkyl group include those having a perfluoroalkyl group at the end. That is, it is preferably a group represented by the following general formula.
(C _p F _{2p + 1} ) − (C _q H _2q ) −
In the above formula, p is preferably 1 to 30, more preferably 1 to 20, and still more preferably 1 to 10. q is preferably from 0 to 20, more preferably from 0 to 10, and even more preferably from 0 to 5. p + q is 3-30.

k, l, m, n, and p represent an integer of 0 or more, and o is an integer of 1 to 4. Further, when k, l, m, n, o, and p are 2 or more, a plurality of structures in parentheses may be the same or different. For example, when k is 2, two L ¹ existing in the molecule may be the same or different from each other. K, l, m, n in the general formula (I) is preferably an integer of 0 to 6, more preferably an integer of 0 to 4, and any of 0 to 3 It is more preferably an integer, and even more preferably an integer of 0 to 2. As a preferable combination of k, l, m, and n in the general formula (I), a combination in which l = m = 1 and k = n = 0 and a combination in which l = m = 1 and k = n = 1 More preferable combinations include a combination in which l = m = 1 and k = n = 0. o is preferably 1 or 2. p is preferably an integer of 1 to 4, and more preferably 1 or 2.

  The compound represented by the general formula (I) may have a symmetrical molecular structure or may have no symmetry. In addition, the symmetry here means one corresponding to any of point symmetry, line symmetry, or rotational symmetry, and asymmetry means one not corresponding to any of point symmetry, line symmetry, or rotational symmetry. .

The compound represented by formula (I), above mentioned fluorinated alkyl group (Hb), the linking group _{^{(L 1) k -Sp- (L}} 2 -A 1) l -L 3 and -L ⁴ - ( A ² -L ⁵ ) _m -Sp- (L ⁶ ) _n , and T, which is a divalent group having an excluded volume effect. The two fluorinated alkyl groups (Hb) present in the molecule are preferably the same as each other, and the linking group (L ¹ ) _k -Sp- (L ² -A ¹ ) ₁ -L ³ present in the molecule and ^{-L 4 - (a 2 -L 5} ) m -Sp- (L 6) n also is preferably identical to each other. End of Hb- (L ¹⁾ _k -Sp- and -Sp- (L ⁶⁾ _n -Hb is preferably a group represented by any one of formulas below.
(C _p F _{2p + 1} ) − (C _q H _2q ) −
_{(C p F 2p + 1)} - (C q H 2q) -O- (C r H 2r) -
_{(C p F 2p + 1)} - (C q H 2q) -COO- (C r H 2r) -
_{(C p F 2p + 1)} - (C q H 2q) -OCO- (C r H 2r) -
In the above formula, p is preferably 1 to 30, more preferably 1 to 20, and still more preferably 1 to 10. q is preferably from 0 to 20, more preferably from 0 to 10, and even more preferably from 0 to 5. p + q is 3-30. r is preferably from 1 to 10, and more preferably from 1 to 4.
When l in the general formula (I) is 1 or more, terminal Hb- (L ¹ ) _k -Sp-L ² -and -L ⁵ -Sp- (L ⁶ ) _n -Hb are any of the following: A group represented by the general formula is preferred.
_{(C p F 2p + 1)} - (C q H 2q) -O
_{(C p F 2p + 1)} - (C q H 2q) -COO-
_{(C p F 2p + 1)} - (C q H 2q) -O- (C r H 2r) -O-
_{(C p F 2p + 1)} - (C q H 2q) -COO- (C r H 2r) -COO-
_{(C p F 2p + 1)} - (C q H 2q) -OCO- (C r H 2r) -COO-
The definitions of p, q and r in the above formula are the same as the definitions immediately above.
Specific examples of the compound represented by the general formula (I) are shown below. However, the compound represented by the general formula (I) that can be employed in the present invention should not be limitedly interpreted by the following specific examples.

  The compound represented by the general formula (I) is synthesized by appropriately selecting and combining the synthesis methods described in JP-A No. 2002-129162, JP-A No. 2002-97170 and literatures cited in the gazette. can do. Moreover, it can synthesize | combine by combining another well-known synthesis method as needed.

(2) Second alignment control agent The liquid crystal composition preferably contains a second alignment control agent.
There is no restriction | limiting in particular unless the said 2nd orientation control agent is contrary to the meaning of this invention.

  It is preferable that the second alignment control agent is non-polymerizable.

  The protrusion ratio represented by the formula (1) of the second alignment control agent is preferably more than 50%, more preferably more than 50% and 90% or less.

  The second alignment control agent preferably has a perfluoroalkyl chain, and the second alignment control agent preferably has 6 perfluoroalkyl chains.

  The second alignment control agent is preferably contained in an amount of 0.003 to 1.0% by mass, and 0.005 to 1.0% by mass with respect to the polymerizable liquid crystal compound in the liquid crystal composition. Is more preferable.

The second alignment control agent is preferably represented by the following general formula (II). The composition containing the compound represented by the following general formula (II) has an advantage of being easy to use in production.

In the general formula (II), L ¹ , L ² , L ³ , L ⁴ , L ⁵ and L ⁶ are each independently a single bond, —O—, —S—, —CO—, —COO—, —OCO. -, -COS-, -SCO-, -NRCO-, -CONR- (in the general formula (II), R represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms), -NRCO-,- CONR- has the effect of reducing solubility, and more preferably -O-, -S-, -CO-, -COO-, -OCO-, -COS-, because the haze value tends to increase during film formation. -SCO-, and -O-, -CO-, -COO-, and -OCO- are more preferable from the viewpoint of the stability of the compound. The alkyl group that R can take may be linear or branched. As for carbon number, it is more preferable that it is 1-3, and a methyl group, an ethyl group, and n-propyl group can be illustrated.

Sp ¹ , Sp ² , Sp ³ and Sp ⁴ each independently represents a single bond or an alkylene group having 1 to 10 carbon atoms, more preferably a single bond or an alkylene group having 1 to 7 carbon atoms, and more preferably It is a single bond or an alkylene group having 1 to 4 carbon atoms. However, the hydrogen atom of the alkylene group may be substituted with a fluorine atom. The alkylene group may or may not be branched, but a linear alkylene group having no branch is preferred. From the viewpoint of synthesis, it is preferable that Sp ¹ and Sp ⁴ are the same, and Sp ² and Sp ³ are the same.

A ¹ and A ² are trivalent or tetravalent aromatic hydrocarbons. The carbon number of the trivalent or tetravalent aromatic hydrocarbon group is preferably 6 to 22, more preferably 6 to 14, still more preferably 6 to 10, and further preferably 6. More preferred. The trivalent or tetravalent aromatic hydrocarbon group represented by A ¹ or A ² may have a substituent. Examples of such a substituent include an alkyl group having 1 to 8 carbon atoms, an alkoxy group, a halogen atom, a cyano group, or an ester group. For the explanation and preferred ranges of these groups, the corresponding description of T below can be referred to. Examples of the substituent for the trivalent or tetravalent aromatic hydrocarbon group represented by A ¹ or A ² include a methyl group, an ethyl group, a methoxy group, an ethoxy group, a bromine atom, a chlorine atom, and a cyano group. be able to. A molecule having a large number of perfluoroalkyl moieties in the molecule can orient the liquid crystal with a small addition amount, leading to a decrease in haze. Therefore, A ¹ and A ² are tetravalent so as to have a large number of perfluoroalkyl groups in the molecule. It is preferable that From the viewpoint of synthesis, A ¹ and A ² are preferably the same.

で表される二価の基または二価の芳香族複素環基を表す（Ｘは炭素数１〜８のアルキル基、アルコキシ基、ハロゲン原子、シアノ基またはエステル基を表し、Ｙａ、Ｙｂ、Ｙｃ、Ｙｄはおのおの独立して水素原子または炭素数１〜４のアルキル基を表す）であり、より好ましくは

であり、さらに好ましくは

であり、よりさらに好ましくは、

である。
Ｘがとりうるアルキル基の炭素数は１〜８であり、１〜５であることが好ましく、１〜３であることがより好ましい。アルキル基は、直鎖状、分枝状、環状のいずれであってもよく、直鎖状または分枝状であることが好ましい。好ましいアルキル基として、メチル基、エチル基、ｎ−プロピル基、イソプロピル基などを例示することができ、その中でもメチル基が好ましい。Ｘがとりうるアルコキシ基のアルキル部分については、Ｘがとりうるアルキル基の説明と好ましい範囲を参照することができる。Ｘがとりうるハロゲン原子としては、フッ素原子、塩素原子、臭素原子、ヨウ素原子を挙げることができ、塩素原子、臭素原子が好ましい。Ｘがとりうるエステル基としては、Ｒ’ＣＯＯ−で表される基を例示することができる。Ｒ’としては炭素数１〜８のアルキル基を挙げることができる。Ｒ’がとりうるアルキル基の説明と好ましい範囲については、上記のＸがとりうるアルキル基の説明と好ましい範囲を参照することができる。エステルの具体例として、ＣＨ₃ＣＯＯ−、Ｃ₂Ｈ₅ＣＯＯ−を挙げることができる。Ｙａ、Ｙｂ、Ｙｃ、Ｙｄがとりうる炭素数１〜４のアルキル基は、直鎖状であっても分枝状であってもよい。例えば、メチル基、エチル基、ｎ−プロピル基、イソプロピル基などを例示することができる。
前記二価の芳香族複素環基は、５員、６員または７員の複素環を有することが好ましい。５員環または６員環がさらに好ましく、６員環が最も好ましい。複素環を構成する複素原子としては、窒素原子、酸素原子および硫黄原子が好ましい。複素環は、芳香族性複素環であることが好ましい。芳香族性複素環は、一般に不飽和複素環である。最多二重結合を有する不飽和複素環がさらに好ましい。複素環の例には、フラン環、チオフェン環、ピロール環、ピロリン環、ピロリジン環、オキサゾール環、イソオキサゾール環、チアゾール環、イソチアゾール環、イミダゾール環、イミダゾリン環、イミダゾリジン環、ピラゾール環、ピラゾリン環、ピラゾリジン環、トリアゾール環、フラザン環、テトラゾール環、ピラン環、チイン環、ピリジン環、ピペリジン環、オキサジン環、モルホリン環、チアジン環、ピリダジン環、ピリミジン環、ピラジン環、ピペラジン環およびトリアジン環が含まれる。二価の複素環基は置換基を有していてもよい。そのような置換基の例の説明と好ましい範囲については、上記のＡ¹とＡ²の３価または４価の芳香族炭化水素が取り得る置換基に関する説明と記載を参照することができる。 T is

(X represents an alkyl group having 1 to 8 carbon atoms, an alkoxy group, a halogen atom, a cyano group, or an ester group, Ya, Yb, Yc. , Yd each independently represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, and more preferably

And more preferably

And even more preferably

It is.
Carbon number of the alkyl group which X can take is 1-8, it is preferable that it is 1-5, and it is more preferable that it is 1-3. The alkyl group may be linear, branched or cyclic, and is preferably linear or branched. Examples of preferable alkyl groups include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group, and among them, a methyl group is preferable. For the alkyl part of the alkoxy group that X can take, the description and preferred range of the alkyl group that X can take can be referred to. Examples of the halogen atom that X can take include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom, and a chlorine atom and a bromine atom are preferable. Examples of the ester group that X can take include a group represented by R′COO—. Examples of R ′ include an alkyl group having 1 to 8 carbon atoms. For the description and preferred range of the alkyl group that R ′ can take, the description and preferred range of the alkyl group that X can take can be referred to. Specific examples of the ester include CH ₃ COO— and C ₂ H ₅ COO—. The alkyl group having 1 to 4 carbon atoms that can be taken by Ya, Yb, Yc, and Yd may be linear or branched. For example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group and the like can be exemplified.
The divalent aromatic heterocyclic group preferably has a 5-membered, 6-membered or 7-membered heterocyclic ring. 5-membered or 6-membered rings are more preferred, and 6-membered rings are most preferred. As the hetero atom constituting the heterocyclic ring, a nitrogen atom, an oxygen atom and a sulfur atom are preferable. The heterocycle is preferably an aromatic heterocycle. The aromatic heterocycle is generally an unsaturated heterocycle. An unsaturated heterocyclic ring having the most double bond is more preferable. Examples of heterocyclic rings include furan ring, thiophene ring, pyrrole ring, pyrroline ring, pyrrolidine ring, oxazole ring, isoxazole ring, thiazole ring, isothiazole ring, imidazole ring, imidazoline ring, imidazolidine ring, pyrazole ring, pyrazoline Ring, pyrazolidine ring, triazole ring, triazane ring, tetrazole ring, pyran ring, thiyne ring, pyridine ring, piperidine ring, oxazine ring, morpholine ring, thiazine ring, pyridazine ring, pyrimidine ring, pyrazine ring, piperazine ring and triazine ring included. The divalent heterocyclic group may have a substituent. For the explanation and preferred ranges of examples of such substituents, reference can be made to the explanations and descriptions regarding the substituents that can be taken by the trivalent or tetravalent aromatic hydrocarbons of A ¹ and A ² .

  Hb represents a perfluoroalkyl group having 2 to 30 carbon atoms, more preferably a perfluoroalkyl group having 3 to 20 carbon atoms, and still more preferably a perfluoroalkyl group having 3 to 10 carbon atoms. The perfluoroalkyl group may be linear, branched or cyclic, but is preferably linear or branched, and more preferably linear.

m and n are each independently 2 or 3, and a plurality of parenthesized structures may be the same or different from each other, but are preferably the same. M and n in the general formula (II) are determined by the valences of A ¹ and A ² described above, and a preferable range is also determined by a preferable range of the valences of A ¹ and A ² . It is not limited to any theory that a compound in which m and n are 2 or 3 has a remarkably good alignment control performance and haze reduction performance even if the addition amount is small as compared with a conventionally known compound and n is 1. Although it does not do, it is estimated that it originates in the fluorine content in a compound.
o and p are each independently an integer of 0 or more, and when o and p are 2 or more, a plurality of Xs may be the same or different from each other. o is preferably 1 or 2. p is preferably an integer of 1 to 4, and more preferably 1 or 2.

  The compound represented by the general formula (II) may have a symmetrical molecular structure or may have no symmetry. In addition, the symmetry here means one corresponding to any of point symmetry, line symmetry, or rotational symmetry, and asymmetry means one not corresponding to any of point symmetry, line symmetry, or rotational symmetry. .

The compound represented by the general formula (II) includes the perfluoroalkyl group (Hb), the linking group-(-Sp ¹ -L ¹ -Sp ² -L ² ) _m -A ¹ -L ³ -and -L described above. ^{4 -A 2 - (L 5 -Sp} 3 -L 6 -Sp 4 -) n -, and is preferably a compound which is a combination of T is a divalent group having the excluded volume effect. The two perfluoroalkyl groups (Hb) present in the molecule are preferably the same as each other, and the linking group present in the molecule-(-Sp ¹ -L ¹ -Sp ² -L ² ) _m -A ¹ -L ³ - and ^{-L 4 -A 2 - (L 5} -Sp 3 -L 6 -Sp 4 -) n - also is preferably identical to each other. Hb-Sp ¹ -L ¹ -Sp ² end - and -Sp ³ -L ⁶ -Sp ⁴ -Hb is preferably a group represented by any one of formulas below.
(C _a F _{2a + 1} ) − (C _b H _2b ) −
(C _a F _{2a + 1} )-(C _b H _2b ) -O- (C _r H _2r )-
(C _a F _{2a + 1} ) — (C _b H _2b ) —COO— (C _r H _2r ) —
(C _a F _{2a + 1} )-(C _b H _2b ) -OCO- (C _r H _2r )-
In the above formula, a is preferably 2 to 30, more preferably 3 to 20, and still more preferably 3 to 10. b is preferably 0 to 20, more preferably 0 to 10, and further preferably 0 to 5. a + b is 3-30. r is preferably from 1 to 10, and more preferably from 1 to 4.
In addition, Hb-Sp ¹ -L ¹ -Sp ² -L ² -and -L ⁵ -Sp ³ -L ⁶ -Sp ⁴ -Hb at the end of the general formula (II) are represented by any one of the following general formulas. It is preferred that
(C _a F _{2a + 1} ) − (C _b H _2b ) —O
(C _a F _{2a + 1} )-(C _b H _2b ) —COO—
(C _a F _{2a + 1} )-(C _b H _2b ) —O— (C _r H _2r ) —O—
(C _a F _{2a + 1} )-(C _b H _2b ) —COO— (C _r H _2r ) —COO—
(C _a F _{2a + 1} )-(C _b H _2b ) —OCO— (C _r H _2r ) —COO—
The definitions of a, b and r in the above formula are the same as the definitions immediately above.
Specific examples of the compound represented by the general formula (II) are shown below. However, the compound represented by the general formula (II) that can be employed in the present invention should not be limitedly interpreted by the following specific examples.

  The compound represented by the general formula (II) is synthesized by appropriately selecting and combining the synthesis methods described in JP-A No. 2002-129162, JP-A No. 2002-97170, and literatures cited therein. can do. Moreover, it can synthesize | combine by combining another well-known synthesis method as needed.

-Other ingredients-
In addition to the polymerizable liquid crystal compound, the optically active compound, the polymerization initiator, and the alignment control agent, the liquid crystal composition can contain a solvent and other additives (for example, cellulose ester) as necessary.

  As a solvent for the liquid crystal composition, an organic solvent is preferably used. Examples of organic solvents include amides (eg, N, N-dimethylformamide), sulfoxides (eg, dimethyl sulfoxide), heterocyclic compounds (eg, pyridine), hydrocarbons (eg, benzene, hexane), alkyl halides (eg, , Chloroform, dichloromethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone, cyclohexanone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.

-Film formation method-
The film forming method of the film having the cholesteric liquid crystal structure is not particularly limited, and the film having the cholesteric liquid crystal structure may be formed by forming the liquid crystal composition containing the polymerizable liquid crystal compound by a method such as coating. it can. A film having the cholesteric liquid crystal structure can be manufactured by applying a coating liquid containing the polymerizable liquid crystal compound on a substrate, and a liquid containing the cholesteric liquid crystal material is applied onto an alignment film, and a liquid crystal layer is formed. By forming the film, a film having a cholesteric liquid crystal structure can be produced. In the method for producing a light interference pigment of the present invention, it is preferable to produce a film having the cholesteric liquid crystal structure by applying a coating liquid containing the polymerizable liquid crystal compound on a substrate. The film having a cholesteric liquid crystal structure preferably exhibits optical anisotropy.

Light irradiation for the polymerization of the liquid crystal compound is preferably performed using ultraviolet rays. The irradiation energy is preferably ^{20mJ / cm 2 ~50J / cm 2} , further preferably 100 to 800 mJ / cm ^2. Moreover, there is no restriction | limiting in particular about the time which irradiates the said coating film with an ultraviolet-ray, However, It will be determined from the viewpoint of both sufficient intensity | strength and productivity of a cured film. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.

An example of a manufacturing method is
(A) Applying the liquid crystal composition containing an alignment control agent and a polymerizable (curable) liquid crystal compound on the surface of a substrate such as a transparent plastic resin film, to obtain a cholesteric liquid crystal phase;
(B) irradiating the liquid crystal composition with ultraviolet rays to advance a curing reaction, fixing a cholesteric liquid crystal phase to form a light reflection layer;
Is a production method comprising at least
The method for producing a light interference pigment of the present invention comprises a light reflecting layer that reflects right circularly polarized light obtained by curing and fixing the alignment state of at least one polymerizable liquid crystal compound, the film having the cholesteric liquid crystal structure; It is preferable to manufacture by laminating a light reflecting layer that reflects left circularly polarized light obtained by curing and fixing the alignment state of at least one polymerizable liquid crystal compound.
By repeating the steps (A) and (B) twice on one surface of the substrate, a film having a cholesteric liquid crystal structure having the structure shown in FIG. 1 (the substrate is not shown in FIG. 1) is manufactured on the substrate. It is possible to form a film (light reflecting layer) having a cholesteric liquid crystal structure in which the number of stacked layers is further increased by repeating the process.

(A) Process In the (A) process, first, the liquid crystal composition is applied to the surface of the substrate or the lower light reflection layer. The liquid crystal composition is preferably prepared as a coating solution in which a material is dissolved and / or dispersed in a solvent.

  Next, it is preferable that the liquid crystal composition applied to the surface to become a coating film is in a cholesteric liquid crystal phase. In an embodiment in which the liquid crystal composition is prepared as a coating solution containing a solvent, the coating film may be dried and the solvent may be removed to obtain a cholesteric liquid crystal phase. Moreover, in order to set it as the transition temperature to a cholesteric liquid crystal phase, you may heat the said coating film if desired. For example, the cholesteric liquid crystal phase can be stably formed by heating to the temperature of the isotropic phase and then cooling to the cholesteric liquid crystal phase transition temperature. The liquid crystal phase transition temperature of the liquid crystal composition is preferably in the range of 10 to 250 ° C., more preferably in the range of 10 to 150 ° C. from the viewpoint of production suitability and the like. When the temperature is lower than 10 ° C., a cooling step or the like may be required to lower the temperature to a temperature range exhibiting a liquid crystal phase. When the temperature exceeds 200 ° C., a high temperature is required to make the isotropic liquid state higher than the temperature range once exhibiting the liquid crystal phase, which is disadvantageous from waste of thermal energy, deformation of the substrate, and alteration.

(B) Process Next, in the process of (B), it is preferable to irradiate an ultraviolet-ray to the coating film used as the state of the cholesteric liquid crystal phase, and to advance hardening reaction. For ultraviolet irradiation, a light source such as an ultraviolet lamp is used. In this step, it is preferable that a curing reaction of the liquid crystal composition proceeds by irradiating ultraviolet rays, the cholesteric liquid crystal phase is fixed, and a light reflecting layer is formed.

  In order to accelerate the curing reaction, ultraviolet irradiation may be performed under heating conditions. Moreover, it is preferable to maintain the temperature at the time of ultraviolet irradiation in the temperature range which exhibits a cholesteric liquid crystal phase so that a cholesteric liquid crystal phase may not be disturbed. Also, since the oxygen concentration in the atmosphere is related to the degree of polymerization, if the desired degree of polymerization is not reached in the air and the film strength is insufficient, the oxygen concentration in the atmosphere is reduced by a method such as nitrogen substitution. It is preferable. A preferable oxygen concentration is preferably 10% or less, more preferably 7% or less, and most preferably 3% or less. The reaction rate of the curing reaction (for example, polymerization reaction) that proceeds by irradiation with ultraviolet rays is 70% or more from the viewpoint of maintaining the mechanical strength of the layer and suppressing unreacted substances from flowing out of the layer. Preferably, it is 80% or more, more preferably 90% or more. In order to improve the reaction rate, a method of increasing the irradiation amount of ultraviolet rays to be irradiated and polymerization under a nitrogen atmosphere or heating conditions are effective. Moreover, after superposing | polymerizing once, the method of hold | maintaining at a temperature higher than superposition | polymerization temperature, and pushing a reaction further by thermal polymerization reaction, and the method of irradiating an ultraviolet-ray again can also be used. The reaction rate can be measured by comparing the absorption intensity of the infrared vibration spectrum of a reactive group (for example, a polymerizable group) before and after the reaction proceeds.

In the above process, the cholesteric liquid crystal phase is fixed and the light reflecting layer is formed. Here, the state in which the liquid crystal phase is “fixed” is the most typical and preferred mode in which the orientation of the liquid crystal compound in the cholesteric liquid crystal phase is maintained. However, it is not limited to this, and specifically, it is usually 0 ° C. to 50 ° C., and under severer conditions, in the temperature range of −30 ° C. to 70 ° C., the layer has no fluidity, and 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 form. In the present invention, the alignment state of the cholesteric liquid crystal phase is preferably fixed by a curing reaction that proceeds by ultraviolet irradiation.
In the present invention, it is sufficient that the optical properties of the cholesteric liquid crystal phase are maintained in the layer, and finally the liquid crystalline mixture in the light reflecting layer no longer needs to exhibit liquid crystallinity. For example, the liquid crystalline mixture may have a high molecular weight due to a curing reaction and may no longer have liquid crystallinity.

<Structure of film having cholesteric liquid crystal structure>
As described above, the film having the cholesteric liquid crystal structure has a liquid crystal film (hereinafter sometimes abbreviated as a liquid crystal film) formed by fixing a cholesteric liquid crystal phase.
In the present invention, the film having the cholesteric liquid crystal structure is preferably a laminate of two or more layers. That is, the liquid crystal film preferably has two or more layers having the cholesteric liquid crystal structure. FIG. 1 shows an example of a laminated structure of a film 1 having a cholesteric liquid crystal structure, and reference numerals 15a and 15b denote light reflecting layers, respectively.
The light reflecting layers 15a and 15b are preferably films having a cholesteric liquid crystal structure, and preferably exhibit light selective reflectivity for reflecting light of a specific wavelength based on the helical pitch of the cholesteric liquid crystal phase. In one embodiment of the present invention, it is preferable that the adjacent light reflecting layers 15a and 15b have opposite spiral directions of the respective cholesteric liquid crystal phases and the same reflection center wavelength λ ₁₅ .

The selective reflection wavelength is not particularly limited. For example, when a heat ray heat shielding function is provided, the spectral distribution of solar energy intensity shows a general tendency that the shorter the wavelength, the higher the energy, but the infrared wavelength. In the spectral distribution of the region, two energy intensity peaks exist at wavelengths of 950 to 1130 nm and wavelengths of 1130 to 1350 nm. At least one pair of light reflecting layers having a central wavelength of selective reflection in the range of 1010 to 1070 nm (more preferably 1020 to 1060 nm), and a central wavelength of selective reflection of 1190 to 1290 nm (more preferably 1200 to 1280 nm) By utilizing at least one pair of light reflecting layers in the range, light corresponding to the two peaks can be more efficiently reflected, and as a result, the heat shielding property can be further improved.
On the other hand, in the present invention, the selective reflection wavelength of the film having the cholesteric liquid crystal structure is preferably 420 nm or less.

  The thickness of each light reflecting layer is about 1 μm to 8 μm (preferably about 3 to 7 μm). However, it is not limited to these ranges. By adjusting the type and concentration of materials (mainly polymerizable liquid crystal compound and chiral agent) used for forming the layer, a light reflecting layer having a desired helical pitch can be formed. Moreover, the thickness of a layer can be made into a desired range by adjusting the application quantity.

  As described above, the adjacent light reflecting layers 15a and 15b have the spiral directions of the respective cholesteric liquid crystal phases opposite to each other, and similarly, the adjacent light reflecting layers 16a and 16b have the spiral directions of the respective cholesteric liquid crystal phases. It is preferable that they are opposite to each other. As described above, by arranging a light reflection layer made of a cholesteric liquid crystal phase in the opposite direction and having the same selective reflection center wavelength in the vicinity, both the left circularly polarized light and the right circularly polarized light having the same wavelength can be reflected. .

For example, the light that has passed through the light reflecting layer 16b (the light that has been reflected by the right circularly polarized light having the wavelength λ ₁₆ and only the left circularly polarized light is transmitted) is selected so that the next light passes through 15a and 15b instead of 16b. when the center wavelength of the reflected is not lambda _16, left-handed circularly polarized light component of the wavelength lambda ₁₆ will be the size of the helical pitch passes through different cholesteric liquid crystal layer. In this case, the left circularly polarized light component having the wavelength λ ₁₆ is slightly affected by the optical rotation of the cholesteric liquid crystal phase in the other light reflecting layers, and changes such as a shift in the wavelength of the left circularly polarized light component. Occurs. Naturally, this phenomenon is not limited to the “left circularly polarized light component of wavelength λ ₁₆ ”, but is a change that occurs when circularly polarized light with a certain wavelength passes through cholesteric liquid crystal phases with different helical pitches. is there. Of course, it is preferable that the set of light reflecting layers be adjacent to each other.

  The mode of the film having a cholesteric liquid crystal structure is not limited to the above mode. A structure in which one or a plurality of light reflecting layers are stacked on one surface of the substrate may be used, or one or more pairs of light reflecting layers are stacked on both surfaces of the substrate. There may be. Moreover, the aspect which has 2 or more sets of light reflection layers which show the same reflection center wavelength may be sufficient.

  The thickness of each light reflecting layer constituting the film having the cholesteric liquid crystal structure is preferably 1 to 10 μm, and more preferably 2 to 7 μm. The thickness of the entire film having the cholesteric liquid crystal structure is preferably 1 to 50 μm from the viewpoint of controlling the thickness of the light interference particles obtained by crushing the film having the cholesteric liquid crystal structure to a preferable range, More preferably, it is 30 micrometers, and it is especially preferable that it is 4-10 micrometers.

(2) Step of Producing Light Interference Particles by Crushing Film Having Cholesteric Liquid Crystal Structure The method for producing a light interference pigment of the present invention includes a step of producing light interference particles by crushing the film having the cholesteric liquid crystal structure.
There is no particular limitation on the step of producing the light interference particles by crushing the film having the cholesteric liquid crystal structure. For example, when the film having the cholesteric liquid crystal structure has a substrate, the film having the cholesteric liquid crystal structure is changed to the substrate. The film from which the substrate has been peeled off is crushed into flakes, and pulverized to the size of fine particles. The light interference particles can be pulverized by drying or wet pulverizing the immobilized cholesteric liquid crystal structure.
In the method for producing a light interference pigment according to the present invention, it is preferable that after the film having the cholesteric liquid crystal structure is crushed, the light interference particles having an average equivalent circle diameter of 100 μm or less are separated using a filter. Examples of the method of sorting the light interference particles using the filter include a method of classifying using a sieve or a cyclone. Among them, it is possible to select and use the light interference particles having an average equivalent circle diameter of 1 to 100 μm, more preferably 1 to 70 μm, and particularly preferably 5 to 50 μm. And desirable from the viewpoint of the physical performance of the film.

(Shape of light interference particles)
The shape of the light interference particles is not particularly limited, and may be spherical, circular, elliptical, polygonal, rod, or fibrous. In the method for producing a light interference pigment of the present invention, the light interference particles are preferably flat (flat or flat), more preferably circular flat.
The thickness of the flat light interference particles such as a flat shape or a scale shape is, for example, preferably 1 to 50 μm, more preferably 3 to 30 μm, and particularly preferably 4 to 10 μm.
The flat optical interference particles preferably have an aspect ratio (average equivalent circle diameter / thickness) of 0.1 to 150, more preferably 0.5 to 50, and particularly preferably 1 to 10. preferable.

(Characteristics of light interference particles)
The selective reflection wavelength of the light interference particles is preferably 420 nm or less.
Examples of the method for measuring the selective reflection wavelength of the light interference particles include the following methods.
It can be measured by sealing between two quartz glass plates together with a liquid having the same refractive index as that of the optical interference particles (manufactured by Moritex Co., Ltd., Cargill standard refractive liquid series A).
When the selective reflection wavelength of the light interference particles cannot be directly determined, it may be obtained indirectly by measuring the selective reflection wavelength of the interlayer film for laminated glass to which the light interference particles and the resin are added.

(3) Step of producing a light interference pigment by washing the light interference particles In the method of producing a light interference pigment of the present invention, the light interference particles have at least an SP value of 8.5 to 12 (cal / cm ³ ) ^1/2. And a step of washing at a temperature of 35 ° C. or higher using an organic solvent.
In the state of the film having the cholesteric liquid crystal structure, the light interference particles after the film having the cholesteric liquid crystal structure is not in contact with the interface with the outside will be in contact with the interface with the outside. In the method for producing a light interference pigment of the present invention, among the light interference particles, the light interference obtained after the cleaning is obtained by cleaning the interface corresponding to the inside of the film that is not in contact with the interface with the outside by a specific method. The light reflection performance at the selective reflection wavelength when the pigment is dispersed in the dispersion medium is improved.
Impurities and unnecessary components removed by such a washing step are not particularly limited. For example, a polymerizable liquid crystal compound (residual monomer) remaining unreacted, the chiral agent, the alignment control agent, Examples include light interference particles whose size is sufficiently smaller than a size that exhibits a light interference effect (for example, an average equivalent circle diameter of 5 μm or less), impurities (such as those having no reactive group) originally contained in the polymerizable liquid crystal compound, and the like. However, the present invention is not limited by the types and amounts of impurities and unnecessary components removed by these cleaning steps.
Further, the light interference pigment and organic solvent used in the cleaning step may contain impurities and unnecessary components, and the present invention provides impurities and unnecessary components contained in the light interference pigment and organic solvent used in these cleaning steps. It is not limited by the type or amount.

The method for producing a light interference pigment of the present invention is washed at a temperature of 35 ° C. or higher. When washed at a temperature of 35 ° C. or higher, the polymerizable liquid crystal compound that is a residual monomer is easily washed sufficiently.
The washing temperature is preferably 40 ° C. or higher and lower than the boiling point of the organic solvent, more preferably from the viewpoint of further improving the light reflection performance at the selective reflection wavelength when dispersed in a dispersion medium,
It is especially preferable that it is 40-60 degreeC.

When the SP value of the organic solvent is 12 (cal / cm ³ ) ^1/2 or more, the solubility of the monomer is deteriorated and it is not suitable for washing.
The SP value of the organic solvent is more preferably 8.5 to 10 (cal / cm ³ ) ^1/2 . The material constituting the film having the cholesteric liquid crystal structure or the material used for forming the film is dissolved in an organic solvent having an SP value in the above range.
Examples of the organic solvent having an SP value of 8.5 to 12 (cal / cm ³ ) ^1/2 include butyl acetate, toluene, methyl ethyl ketone, and acetone.
These organic solvents may be used alone or in combination of two or more. However, when two or more organic solvents are mixed and used, the SP values of all the organic solvents used for the washing are It is preferable that it is an organic solvent contained in said range.

  The method for washing the light interference particles using the organic solvent is not particularly limited. The method for immersing the light interference particles in the organic solvent for cleaning, or spraying the organic solvent on the light interference particles. The method of washing can be mentioned. In the method for producing a light interference pigment of the present invention, the light interference particles are preferably immersed in the organic solvent and washed.

In the method for producing a light interference pigment of the present invention, it is preferable that after the optical interference particles are immersed in the organic solvent and washed, a residue obtained by filtering the organic solvent with a filter is collected. Although the light interference particles obtained by pulverization are usually classified by dryness, unnecessary fine particles remain. However, after the optical interference particles are immersed and washed in the organic solvent in this way, unnecessary particles of fine sizes can be removed together when separating the residue obtained by filtering the organic solvent through a filter. Therefore, the light reflection performance at the selective reflection wavelength when dispersed in the dispersion medium is improved.
In addition, a series of washing operations of immersing and filtering the light interference particles in the organic solvent is repeated twice or more from the viewpoint of further improving the light reflection performance at the selective reflection wavelength when dispersed in a dispersion medium. You may go.

  In the method for producing a light interference pigment of the present invention, from the viewpoint of removing unnecessary fine particles, the filtration accuracy of the filter used for filtering the organic solvent is preferably 0.3 to 6 μm, and preferably 0.5 to 3 μm. It is more preferable that By filtering with such a filter with a filtering accuracy to remove unnecessary particles of fine size (for example, the average equivalent circle diameter is 5 μm or less), optical characteristics (particularly selected) than when the unnecessary particles remain in the filtration residue. The light reflectance at the reflection wavelength is improved.

[Light interference pigment]
The light interference pigment of the present invention is produced by the method for producing a light interference pigment of the present invention. Therefore, the light interference pigment of the present invention has good light reflection performance at a selective reflection wavelength when dispersed in a dispersion medium.
The preferred structure and preferred optical properties of the light interference pigment of the present invention are the same as the preferred structure and preferred optical properties of the light interference particles.
The light interference pigment of the present invention is preferably used as a UV reflecting material. There is no restriction | limiting in particular as a use of the light interference pigment of this invention, You may add the light interference pigment of this invention to cosmetics etc.

<Method for producing optical interference pigment dispersion>
The light interference pigment of the present invention can be used for producing a light interference pigment dispersion.

  The method for producing a light interference pigment dispersion preferably includes a step of dispersing the light interference pigment produced by the method for producing a light interference pigment of the present invention in a dispersion medium containing alcohol.

  The main factor that causes the selective reflection wavelength and reflection spectrum peak shape of the light interference pigment dispersion to deviate from that of the light interference pigment before the dispersion is used is that the solvent interferes with the light interference pigment (occurs simultaneously with the elution of the residual monomer). As a result of swelling and the free volume (space) of the liquid crystal layer of the light interference pigment expanding, it is estimated that the birefringence Δn of the light interference pigment decreases due to the surrounding material (for example, resin) entering the gap. Has been. For this reason, alcohol (such as ethanol) that swells due to solvent soaking (which occurs simultaneously with elution of residual monomer) or resin that enters the free volume of the liquid crystal layer of the light interference pigment (such as silicone resin) ) Or the like, or when producing such a light interference pigment dispersion, the cleaning in the method for producing a light interference pigment of the present invention is required.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like 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 specific examples shown below.

[Examples 1-8 and Comparative Examples 1-6]
(Preparation of coating solution)
Coating solutions (A) and (B) shown in the following table were prepared.

(Preparation of a film having a cholesteric liquid crystal structure that reflects ultraviolet light having a wavelength of 380 nm)
(1) Using a wire bar, the prepared coating solution (A) is placed on a substrate film (Fuji Film PET film, Tg 75 ° C.) at room temperature so that the dry film thickness after drying is 4.5 μm. Was applied.
(2) After drying at room temperature for 30 seconds, heat in an atmosphere of 125 ° C. for 2 minutes, and then UV-irradiate at 95 ° C. with a fusion D bulb (lamp 90 mW / cm) at an output of 60% for 6 to 12 seconds. A cholesteric liquid crystal layer film was prepared.
After cooling the cholesteric liquid crystal layer film to room temperature, (1) and (2) are repeated in the same manner except that the coating liquid (B) is applied on the lower cholesteric liquid crystal layer film instead of the substrate in (1). A two-layer laminated film having a cholesteric liquid crystal structure in which a layer reflecting right circularly polarized light and a layer reflecting left circularly polarized light derived from the coating liquids (A) and (B) are laminated in this order on the base film, respectively. did.

(Preparation of UV-reflective optical interference particles)
The produced two-layer laminated film having a cholesteric liquid crystal structure that reflects ultraviolet light having a wavelength of 380 nm was peeled from the substrate.
The peeled two-layer laminated film having a cholesteric liquid crystal structure was crushed into flakes, and further pulverized to the size of fine particles to produce light interference particles.
The particle size of the light interference particles was classified using a sieve. As a result of observing the shape of 300 obtained optical interference particles using an optical microscope, the average thickness was 10 μm and the average equivalent circle diameter was 20 μm.
Moreover, it confirmed using the polarizing microscope that the obtained light interference particle | grains have a cholesteric liquid crystal structure. Furthermore, when the selective reflection wavelength of the obtained light interference particles was confirmed using an ultraviolet-visible near-infrared spectrophotometer V-670 (manufactured by JASCO Corporation), it was about 380 nm.

(Preparation of optical interference pigments by cleaning optical interference particles)
1 g of the light interference particle powder and 100 g of the solvent (organic solvent or water) shown in Table 3 below are placed in a flask, and the temperature of the solvent is adjusted as shown in Table 3 below, followed by stirring with a stirrer for 1 hour. did. The rotation speed of the stirrer was 100 rpm. After stirring, the solution containing the solvent and the light interference particles was filtered through a 1 μm filter paper, and the light interference particles were taken out as a residue on the filter paper.
This agitation and filtration operation was repeated three times. Finally, the mixture was allowed to stand overnight at room temperature and dried to obtain a light interference pigment.

(Evaluation of light reflection performance at selective reflection wavelength of light interference pigment)
1 g of the dried optical interference pigment is mixed with 10 g of acrylic silicone (KP-541 manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.5 g of ethanol (759-48001 manufactured by Wako Pure Chemical Industries, Ltd.), and a thickness of 100 μm is added to the PMMA plate. The optical properties of the coated plate were evaluated according to the following criteria. Practically, it is necessary to have an A or B evaluation, and an A evaluation is preferable.
Evaluation criteria:
A: A reflection spectrum having a reflection peak of 10% or more at 380 nm was observed.
B: The reflection width widened and became broad, but a clear peak was not seen although there was reflection of 1% or more at 380 nm.
C: The reflection width was broadened and the reflection was hardly observed at 380 nm (reflectance less than 1%).
The obtained results are shown in Table 3 below.

[Comparative Example 7]
In Example 1, when the obtained light interference particles were evaluated in the same manner as in Example 1 without solvent washing, the evaluation was C.

[Comparative Example 8]
In Example 1, Bencot (Asahi Kasei Co., Ltd.) impregnated with methyl ethyl ketone (same as Example 3, SP value 9.3, boiling point 79.5 ° C.) on the surface of the two-layer laminated film having a cholesteric liquid crystal structure peeled from the substrate. After wiping twice with a product manufactured by Sensui Co., Ltd., it was pulverized into light interference particles in the same manner as in Example 1. Thereafter, the obtained light interference particles were evaluated in the same manner as in Example 1 without solvent washing, and the evaluation was C.

[Example 9]
Instead of a PET film as a base film, on one side of a long film of triacetylcellulose (Fujitack, manufactured by Fuji Film Co., Ltd., thickness: 100 μm, width: 500 mm, glass transition temperature 145 ° C.) A 5% by weight solution of long-chain alkyl-modified PVA (MP-203, manufactured by Kuraray Co., Ltd.) is applied, dried at 90 ° C. for 4 minutes, and then rubbed to form an alignment film-forming resin having a thickness of 2.0 μm. A film having a layer formed thereon was used.
Other than that, a light interference pigment was produced in the same manner as in Example 3, and the light interference pigment was evaluated. The evaluation was also A.

[Example 10]
In place of PET film as a substrate, a 5% by weight long-chain alkyl-modified poval (MP-203, manufactured by Kuraray Co., Ltd.) solution was applied to one side of a 2 mm thick glass plate in the same manner as in Example 8. Then, after drying at 90 ° C. for 4 minutes, a film in which a rubbing treatment was performed to form an alignment film-forming resin layer having a thickness of 2.0 μm was used. Other than that, a light interference pigment was produced in the same manner as in Example 3, and the light interference pigment was evaluated. The evaluation was also A.

[Example 11]
A light interference pigment was produced in the same manner as in Example 3 except that RM-257 (manufactured by Merck) was used as the rod-like liquid crystal compound, and the light interference pigment was evaluated. The evaluation was also A.

[Example 12]
A light interference pigment was produced in the same manner as in Example 3 except that LC-242 (manufactured by BASF) was used as the rod-like liquid crystal compound, and the light interference pigment was evaluated. The evaluation was also A.

Based on the above results, the light interference pigment obtained by the production method of the present invention has good light reflection performance at a selective reflection wavelength when dispersed in a dispersion medium (particularly when a dispersion containing a silicone resin and alcohol). I found out that
On the other hand, it can be seen from Comparative Example 1 that the light interference pigment produced under conditions where the washing temperature is lower than the lower limit specified in the present invention deteriorates the light reflection performance at the selective reflection wavelength when dispersed in a dispersion medium. It was.
From Comparative Examples 2 to 4, the light interference pigment produced under the condition that the organic solvent used for cleaning exceeds the upper limit value of the SP value defined in the present invention is the light reflection performance at the selective reflection wavelength when dispersed in the dispersion medium. It turned out to get worse.
From Comparative Example 5, the light interference pigment produced under the condition that the organic solvent used for cleaning is lower than the lower limit value of the SP value defined in the present invention deteriorates the light reflection performance at the selective reflection wavelength when dispersed in the dispersion medium. I found out that
From Comparative Example 6, a light interference pigment produced using water, which is a solvent that exceeds the upper limit of the SP value defined in the present invention at the time of washing, as disclosed in JP2011-132512A and International Publication WO96 / 28498, It was found that the light reflection performance at the selective reflection wavelength when dispersed in a dispersion medium deteriorates.
From Comparative Example 7, the light interference pigment produced without washing the particles obtained after pulverization as in JP-A-2000-44451 has a light reflection performance at a selective reflection wavelength when dispersed in a dispersion medium. It turns out that it gets worse.
From Comparative Example 8, even when the surface was washed without crushing a film having a cholesteric liquid crystal structure as in JP 2012-101999 A, the particles obtained after crushing were produced without washing. It was found that the light interference pigment deteriorates the light reflection performance at the selective reflection wavelength when dispersed in the dispersion medium.

1 Film having a cholesteric liquid crystal structure (may include a substrate)
15a Light reflecting layer 15b in which the alignment state (cholesteric liquid crystal phase) of the polymerizable liquid crystal compound is fixed 15b Light reflecting layer in which the alignment state (cholesteric liquid crystal phase) of the polymerizable liquid crystal compound is fixed

Claims (14)

A step of producing a film having a cholesteric liquid crystal structure in which the alignment state of the polymerizable liquid crystal compound is cured and fixed;
Crushing the film having the cholesteric liquid crystal structure to produce light interference particles;
Washing the light interference particles with an organic solvent having an SP value of 8.5 to 12 (cal / cm ³ ) ^1/2 at a temperature of 35 ° C. or higher;
(SP value represents the solubility parameter δ measured by the Hoy method, and is represented by the following formula (1)).
δ = (ΔE / V) ^1/2 formula (1)
(In formula (1), V represents the molar molecular volume of the solvent, and ΔE represents the cohesive energy (evaporation energy).)   A light-reflecting layer that reflects right circularly polarized light obtained by curing and fixing the alignment state of at least one polymerizable liquid crystal compound on the film having the cholesteric liquid crystal structure, and the alignment state of at least one polymerizable liquid crystal compound The method for producing a light interference pigment according to claim 1, wherein the light interference pigment is produced by laminating a light reflecting layer that reflects left circularly polarized light obtained by curing and fixing the light.   The method for producing a light interference pigment according to claim 1, wherein the light interference particles are immersed and washed in the organic solvent.   The method for producing an optical interference pigment according to any one of claims 1 to 3, wherein after the optical interference particles are immersed and washed in the organic solvent, a residue obtained by filtering the organic solvent with a filter is collected. .   The method for producing a light interference pigment according to claim 4, wherein the filter used for filtering the organic solvent has a filtration accuracy of 0.3 to 6 μm.   The method for producing an optical interference pigment according to any one of claims 1 to 5, wherein a temperature of the washing is 40 ° C or more and not more than a boiling point of the organic solvent.   The method for producing a light interference pigment according to any one of claims 1 to 6, wherein the light interference particles have a flat plate shape.   The method for producing a light interference pigment according to claim 1, wherein a selective reflection wavelength of the light interference pigment is 420 nm or less.   The manufacturing method of the optical interference pigment as described in any one of Claims 1-8 whose thickness of the said optical interference particle is 4-10 micrometers.   The light interference pigment according to any one of claims 1 to 9, wherein after the film having the cholesteric liquid crystal structure is crushed, the light interference particles having an average equivalent circle diameter of 100 µm or less are collected using a filter. Manufacturing method.   The manufacturing method of the optical interference pigment as described in any one of Claims 1-10 which apply | coats the coating liquid containing the said polymeric liquid crystal compound on a board | substrate, and manufactures the film | membrane which has the said cholesteric liquid crystal structure.   The method for producing a light interference pigment according to claim 11, wherein the substrate is a plastic film having a glass transition temperature of 150 ° C. or lower.   The alignment state of the polymerizable liquid crystal compound is fixed by a curing reaction that proceeds by irradiating the composition containing the polymerizable liquid crystal compound and a photopolymerization initiator with ultraviolet rays. The manufacturing method of the optical interference pigment of claim | item. The method for producing an optical interference pigment according to any one of claims 1 to 13, wherein the polymerizable liquid crystal compound is a compound represented by the following general formula (X).
Formula ^{(X) Q 1 -L 1 -Cy} 1 -L 2 - (Cy 2 -L 3) n -Cy 3 -L 4 -Q 2
(In General Formula (X), Q ¹ and Q ² are each independently a polymerizable group, L ¹ and L ⁴ are each independently a divalent linking group, and L ² and L ³ are each independently a single group. A bond or a divalent linking group, Cy ¹ , Cy ² and Cy ³ are divalent cyclic groups, and n is 0, 1, 2, or 3.)

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