Ink composition, article and method for making the same

Abstract

The present invention provides an ink composition, which contains a cholesteric pigment and a non-volatile organic compound, wherein the cholesteric pigment contains a cured product of a liquid crystal composition, the liquid crystal composition contains a polymerizable compound, and the absolute value of the difference between the weighted average HSP of the polymerizable compound and the HSP of the organic compound |ΔHSP1| is less than 3.0, or the absolute value of the difference between the weighted average logP of the polymerizable compound and the logP of the organic compound |ΔlogP1| is less than 1.0.

Description

Technical Field

[0001] The present invention relates to ink compositions, and articles and methods of making the same. Background Art

[0002] As one of the coating materials containing a pigment including a cured product of a liquid crystal composition, there is an ink composition containing a cholesteric pigment (Patent Documents 1 to 4).

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Publication No. 2002-114935;

[0006] Patent document 2: Japanese Patent Application Publication No. 2002-121408;

[0007] Patent Document 3: Japanese Patent Application Publication No. 2003-253187;

[0008] Patent document 4: Japanese Patent Application Publication No. 2004-358869. Summary of the invention

[0009] Problem that the invention aims to solve

[0010] Cholesteric pigments are generally formed of a solidified product of a liquid crystal composition in a cholesteric liquid crystal phase, and thus the molecules in the pigment have cholesteric regularity. Therefore, cholesteric pigments are generally capable of reflecting circularly polarized light in one of right-handed and left-handed directions at a wavelength corresponding to the above-mentioned cholesteric regularity and transmitting circularly polarized light in a direction opposite to the right-handed direction. Therefore, when an ink composition containing the cholesteric pigment is applied to form a display layer, the display layer can selectively reflect circularly polarized light in one direction.

[0011] However, when a display layer formed by a conventional ink composition is placed in a high temperature and high humidity environment, the wavelength of circularly polarized light that the cholesteric pigment can selectively reflect may shift. Due to this shift, the wavelength of circularly polarized light reflected by the display layer usually changes, which may cause an undesirable change in the color of the display layer. Therefore, it is desirable to suppress the change in the wavelength of circularly polarized light that the cholesteric pigment contained in the display layer can selectively reflect in a high temperature and high humidity environment, and improve the durability to the high temperature and high humidity environment.

[0012] The present invention is made in view of the above problems, and its purpose is to provide: an ink composition capable of suppressing the change in the wavelength of circularly polarized light that can be reflected by cholesteric pigments in a high temperature and high humidity environment; and an article having a display layer obtained by coating the ink composition and a method for manufacturing the same.

[0013] Solutions for solving problems

[0014] The present inventors have conducted intensive studies to solve the above problems. As a result, the present inventors have found that the above problems can be solved by combining an organic compound having an HSP or logP within a specific range with a cholesteric pigment, thereby completing the present invention.

[0015] That is, the present invention includes the following contents.

[0016] [1] An ink composition comprising a cholesteric pigment and a non-volatile organic compound, wherein the cholesteric pigment comprises a cured product of a liquid crystal composition, and the liquid crystal composition comprises a polymerizable compound,

[0017] The absolute value of the difference between the weighted average of the HSP of the polymerizable compound and the HSP of the organic compound |ΔHSP1| is 3.0 or less, or

[0018] The absolute value |ΔlogP1| of the difference between the weighted average of logP of the polymerizable compound and the logP of the organic compound is 1.0 or less.

[0019] [2] The ink composition according to [1], wherein the liquid crystal composition contains the same compound as the organic compound.

[0020] [3] The ink composition according to [1] or [2], wherein the organic compound is a liquid crystal compound.

[0021] [4] The ink composition according to any one of [1] to [3], wherein the square root of the sum of the squares of the absolute value |ΔHSP1| and the absolute value |ΔlogP1| {|ΔHSP1| 2 +|ΔlogP1| 2} 1 / 2 Below 5.0.

[0022] [5] The ink composition according to any one of [1] to [4], wherein the square root of the sum of the squares of the absolute value |ΔHSP1| and the absolute value |ΔlogP1| {|ΔHSP1| 2 +|ΔlogP1| 2} 1 / 2 Below 1.5.

[0023] [6] The ink composition according to any one of [1] to [5], wherein the polymerizable compound comprises a main component monomer,

[0024] The amount of the main component monomer contained in the liquid crystal composition is 50% by weight or more relative to 100% by weight of the non-volatile component of the liquid crystal composition.

[0025] The above-mentioned main component monomer is the same as the above-mentioned organic compound.

[0026] [7] The ink composition according to any one of [1] to [6], wherein the ink composition contains an organic solvent, and the organic solvent contains a diluent,

[0027] The absolute value |ΔHSP2| of the difference between the weighted average of the HSP of the polymerizable compound and the HSP of the diluent is greater than 2.

[0028] [8] The ink composition according to [7], wherein the diluent has an HSP of 26 or more.

[0029] [9] The ink composition according to [7], wherein the diluent has an HSP of 18 or less.

[0030]

[10] The ink composition according to any one of [1] to [9], wherein the polymerizable compound includes a compound represented by the following formula (X1).

[0031] [Chemical formula 1]

[0032]

[0033]

[11] The ink composition according to any one of [1] to

[10] , wherein the cholesteric pigment has a selective reflection wavelength range capable of reflecting circularly polarized light in one rotational direction and transmitting circularly polarized light in a rotational direction opposite to the rotational direction.

[0034] The wavelength width of the selective reflection wavelength range is 50 nm or more.

[0035]

[12] The ink composition according to

[11] , wherein the selective reflection wavelength range includes the entire visible light wavelength range.

[0036]

[13] The ink composition according to any one of [1] to

[12] , wherein the cholesteric pigment is in the form of small flakes.

[0037]

[14] The ink composition according to

[13] , wherein the thickness of the cholesteric pigment is 20 μm or less.

[0038]

[15] The ink composition according to any one of [1] to

[14] , wherein the amount of the organic compound is 0.5 parts by weight or more and 10 parts by weight or less relative to 100 parts by weight of the cholesteric pigment.

[0039]

[16] An ink composition according to any one of [1] to

[15] , wherein, when a display layer obtained by applying the ink composition is subjected to a durability test in an environment of temperature 90°C and humidity 80% RH for 14 days, the change in the center wavelength of the selective reflection wavelength range of the cholesteric pigment is less than 15 nm.

[0040]

[17] An article having a display layer obtained by coating the ink composition according to any one of [1] to

[16] .

[0041]

[18] A method for manufacturing an article, comprising the step of applying the ink composition described in any one of [1] to

[16] to form a display layer.

[0042] Effects of the Invention

[0043] According to the present invention, there can be provided: an ink composition capable of suppressing changes in the wavelength of circularly polarized light that can be reflected by a cholesteric pigment in a high temperature and high humidity environment; an article having a display layer obtained by coating the ink composition; and a method for producing the article. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 This is a graph showing a standard curve used for measuring logP in Examples and Comparative Examples of the present invention. DETAILED DESCRIPTION

[0045] The present invention will be described in detail below by showing embodiments and examples. However, the present invention is not limited to the embodiments and examples described below, and can be implemented with arbitrary changes without departing from the scope of the claims of the present invention and their equivalents.

[0046] In the following description, unless otherwise specified, the term "(meth)acryloyl" includes acryloyl, methacryloyl and a combination thereof.

[0047] In the following description, unless otherwise specified, the direction of the elements being "parallel" may include an error within the range of, for example, ±5°, preferably ±3°, and more preferably ±1°, within the range not impairing the effects of the present invention.

[0048] [1. Overview of ink composition]

[0049] An ink composition according to one embodiment of the present invention includes a cholesteric pigment and a non-volatile organic compound, wherein the cholesteric pigment includes a solidified product of a liquid crystal composition, and the liquid crystal composition includes a polymerizable compound. In the following description, the solidified product of the liquid crystal composition is sometimes referred to as a "liquid crystal solidified product". The organic compound satisfies at least one of the following necessary conditions (i) and necessary conditions (ii), and preferably satisfies both.

[0050] Requirement (i): The absolute value of the difference between the weighted average of the HSP of the polymerizable compound and the HSP of the organic compound |ΔHSP1| is 3.0 or less.

[0051] Requirement (ii): The absolute value of the difference between the weighted average of the logP of the polymerizable compound and the logP of the organic compound, |ΔlogP1|, is 1.0 or less.

[0052] “HSP” refers to Hildebrand solubility parameter. HSP can be calculated by the Y-MB method.

[0053] "logP" means 1-octanol / water partition coefficient. The logP of a certain sample compound can be measured by the following determination method. A sample solution containing 1% by weight of the sample compound is prepared, and HPLC / ELSD analysis (high performance liquid chromatography / evaporative light scattering detection analysis) is performed in accordance with the method of JIS 7260-117:2006 {Determination of the partition coefficient (1-octanol / water) - high performance liquid chromatography} to determine the elution time (rt). On the other hand, a standard compound whose logP value is known and recorded in JIS7260-117:2006 is subjected to HPLC / ELSD analysis in the same manner as the above-mentioned sample compound, and the elution time (rt) is determined. Based on the determination results of the standard compound, a standard curve representing the relationship between the elution time and logP is prepared. Then, the logP of the sample compound is obtained by substituting the elution time measured for the sample compound into the above-mentioned standard curve.

[0054] In the following description, the nonvolatile organic compound satisfying at least one of the requirements (i) and (ii) is sometimes referred to as a "stabilizer". In addition, the weighted average of the HSP of the polymerizable compounds included in the liquid crystal composition is sometimes referred to as the "weighted average HSP", and the weighted average of the logP of the polymerizable compounds included in the liquid crystal composition is sometimes referred to as the "weighted average logP". The weighted average means a weighted average based on weight.

[0055] When the ink composition is applied to form a display layer, the ink composition can exert an effect of suppressing changes in the wavelength of circularly polarized light that can be reflected by the cholesteric pigment included in the display layer in a high temperature and high humidity environment.

[0056] [2. Cholesteric pigments]

[0057] The cholesteric pigment includes a cured product of a liquid crystal composition (i.e., a liquid crystal cured product), wherein the liquid crystal composition includes a polymerizable compound. The liquid crystal composition includes one or more polymerizable compounds and may further include a non-polymerizable compound as required.

[0058] The liquid crystal cured material as a cured material of the liquid crystal composition can be obtained by curing the liquid crystal composition by curing reactions such as polymerization and crosslinking of the polymerizable compound. Therefore, the liquid crystal cured material can contain a polymer polymerized by the polymerizable compound. In addition, a part of the polymerizable compound can remain without polymerization, so the liquid crystal cured material can also contain unreacted polymerizable compounds. Furthermore, the above-mentioned polymerizable compound and its polymer can also be crosslinked. Usually, the cholesteric pigment has a layer formed by the above-mentioned liquid crystal cured material.

[0059] The liquid crystal cured product contained in the cholesteric pigment contains molecules having cholesteric regularity. Generally, a part or all of the molecules of the polymerizable compound and the polymer contained in the liquid crystal cured product have cholesteric regularity in the liquid crystal cured product.

[0060] Cholesteric regularity refers to a structure in which the molecular axes are arranged in a certain direction on a certain plane, but the direction of the molecular axes on the next plane overlapping it is slightly offset at an angle, and then the angle is further offset on the next plane, and like this, as the planes arranged in overlapping order are passed through one by one, the angle of the molecular axes in the plane gradually shifts (twists). That is, when the molecules inside a certain layer have cholesteric regularity, the molecules are arranged in a manner such that the molecular axes become a certain direction on a certain first plane inside the layer. On the next second plane inside the layer overlapping the first plane, the direction of the molecular axes is slightly offset at an angle from the direction of the molecular axes in the first plane. On the next third plane further overlapping the second plane, the direction of the molecular axes is further offset at an angle from the direction of the molecular axes in the second plane. Like this, in the planes arranged in overlapping order, the angles of the molecular axes in the plane gradually shift (twists) one by one. A structure in which the direction of the molecular axes is gradually twisted like this is usually a helical structure, which is an optically chiral structure.

[0061] As described above, the liquid crystal solidified material containing molecules with cholesteric regularity can usually play the circular polarized light separation function. "Circular polarized light separation function" means the function of reflecting circular polarized light of one rotation direction between right-handed and left-handed and transmitting circular polarized light of the opposite rotation direction. Therefore, in the wavelength range that can play the circular polarized light separation function, the cholesteric pigment containing the liquid crystal solidified material can reflect circular polarized light of one rotation direction and transmit circular polarized light of the rotation direction opposite to the rotation direction. In the above reflection, the circular polarized light is reflected in a state of maintaining its chirality. In the following description, the wavelength range in which such cholesteric pigment can play the circular polarized light separation function is sometimes appropriately referred to as "selective reflection wavelength range". The reflectivity of cholesteric pigment to non-polarized light in the selective reflection wavelength range is usually 35% to 50%, preferably 40% to 50%. Since the liquid crystal solidified material can play the circular polarized light separation function, the cholesteric pigment containing the liquid crystal solidified material can function as a pigment.

[0062] From the viewpoint of easily obtaining a liquid crystal cured product containing molecules with cholesteric regularity, the liquid crystal composition is preferably a cholesteric liquid crystal composition. A cholesteric liquid crystal composition refers to a liquid crystal composition in which the liquid crystal compound contained in the liquid crystal composition is able to present a liquid crystal phase (cholesteric liquid crystal phase) with cholesteric regularity when the liquid crystal compound contained in the liquid crystal composition is oriented. Here, the material referred to as a "liquid crystal composition" for convenience includes not only a mixture of two or more substances, but also a material formed of a single substance.

[0063] The liquid crystal composition includes a liquid crystal compound. In addition, the liquid crystal composition may also include an orientation aid, a chiral agent, a surfactant, a polymerization initiator and other arbitrary components as needed. The liquid crystal compound and part or all of the arbitrary components may be polymerizable compounds having polymerizability.

[0064] (Liquid Crystalline Compound)

[0065] The liquid crystal compound contained in the liquid crystal composition is preferably a cholesteric liquid crystal compound. A cholesteric liquid crystal compound refers to a compound that can exhibit cholesteric liquid crystal properties. Using a liquid crystal composition containing a cholesteric liquid crystal compound, the liquid crystal composition is cured in a state of being in a cholesteric liquid crystal phase, thereby successfully obtaining a liquid crystal cured product containing molecules having cholesteric regularity.

[0066] The liquid crystal compound preferably has polymerizability and is therefore preferably a polymerizable compound.

[0067] Liquid crystal compounds having polymerizability usually have reactive groups. Preferred reactive groups include, for example, (meth)acryloyl, epoxy, thioepoxy, oxetanyl, thietanyl, aziridine, pyrrolyl, fumarate, cinnamoyl, isocyanate, isothiocyanate, amino, hydroxyl, carboxyl, alkoxysilyl, The number of reactive groups in one molecule of liquid crystal compound can be 1, and from the viewpoint of obtaining a cholesteric pigment with excellent durability, it is preferably 2 or more. In addition, when one molecule of liquid crystal compound has a plurality of reactive groups, these reactive groups may be the same or different.

[0068] Preferred polymerizable liquid crystal compounds include, for example, rod-shaped liquid crystal compounds having two or more reactive groups in one molecule. Specific examples of rod-shaped liquid crystal compounds include compounds represented by formula (1).

[0069] R 3 -C 3 -D 3 -C 5 -MC 6 -D 4 -C 4 -R 4 Formula (1)

[0070] In formula (1), R 3 and R 4 Each independently represents a reactive group. 3 and R 4 Any one selected from the reactive groups exemplified above is preferred.

[0071] In formula (1), D 3 and D 4 Each independently represents a group selected from a single bond, a linear or branched alkyl group having 1 to 20 carbon atoms, and a linear or branched oxyalkylene group having 1 to 20 carbon atoms.

[0072] In formula (1), C 3 ~C 6 Each independently represents a group selected from a single bond, -O-, -S-, -SS-, -CO-, -CS-, -OCO-, -CH2-, -OCH2-, -CH=NN=CH-, -NHCO-, -O-(C=O)-O-, -CH2-(C=O)-O-, and -CH2O-(C=O)-.

[0073] In formula (1), M represents a mesogenic group. Preferred mesogenic groups include, for example, unsubstituted or substituted azomethines, azoxyls, phenyls, biphenyls, terphenyls, naphthalenes, anthracenes, benzoates, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldiphenylamines, and the like. A group in which two to four skeletons that are the same or different from each other in alkanes, diphenylacetylenes, and alkenylcyclohexylbenzonitriles are bonded by bonding groups such as -O-, -S-, -SS-, -CO-, -CS-, -OCO-, -CH2-, -OCH2-, -CH=NN=CH-, -NHCO-, -O-(C=O)-O-, -CH2-(C=O)-O-, and -CH2O-(C=O)-.

[0074] Examples of the substituent that the mesogenic group M may have include a halogen atom, an alkyl group having 1 to 10 carbon atoms which may have a substituent, a cyano group, a nitro group, a -OR 5 、-OC(=O)-R 5 、-C(=O)-OR 5 、-OC(=O)-OR 5 、-NR 5 -C(=O)-R 5 、-C(=O)-NR 5 R 7 , or -OC(=O)-NR 5 R 7 Here, R 5 and R 7 represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. 5 and R 7 In the case of an alkyl group, -O-, -S-, -OC(=O)-, -C(=O)-O-, -OC(=O)-O-, -NR 6 -C(=O)-, -C(=O)-NR 6 -、-NR 6 -, or -C(=O)- (except for the case where two or more -O- and -S- are each adjacently inserted). 6 It represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms.

[0075] Examples of the substituent in the above-mentioned “alkyl group having 1 to 10 carbon atoms which may have a substituent” include a halogen atom, a hydroxyl group, a carboxyl group, a cyano group, an amino group, an alkoxy group having 1 to 6 carbon atoms, an alkoxyalkoxy group having 2 to 8 carbon atoms, an alkoxyalkoxyalkoxy group having 3 to 15 carbon atoms, an alkoxycarbonyl group having 2 to 7 carbon atoms, an alkylcarbonyloxy group having 2 to 7 carbon atoms, and an alkoxycarbonyloxy group having 2 to 7 carbon atoms.

[0076] The rod-shaped liquid crystal compound preferably has an asymmetric structure. Here, an asymmetric structure refers to a structure in which the structure part on one side bonded to the mesogenic group is different from the structure part on the other side. For example, in formula (1), the mesogenic group M is the center, R 3 -C 3 -D 3 -C 5 -with-C 6 -D 4 -C 4 -R 4 Different structures: By using a compound with an asymmetric structure as the rod-like liquid crystal compound, the alignment uniformity can be further improved.

[0077] Preferred specific examples of the liquid crystal compound include the following compounds (B1) to (B9). The liquid crystal compound may be used alone or in combination of two or more at any ratio.

[0078] [Chemical formula 2]

[0079]

[0080] Among them, as the liquid crystal compound, a compound represented by the following formula (X1) is particularly preferred.

[0081] [Chemical formula 3]

[0082]

[0083] The liquid crystal compound may be used alone or in combination of two or more at any ratio.

[0084] The molecular weight of the liquid crystal compound is preferably 600 or more, preferably 3000 or less, more preferably 2000 or less, particularly preferably 1500 or less.

[0085] When the liquid crystal compound is a polymerizable compound, the HSP of the polymerizable liquid crystal compound is preferably 19 or more, more preferably 21 or more, particularly preferably 23 or more, preferably 29 or less, more preferably 27 or less, particularly preferably 25 or less.

[0086] When the liquid crystal compound is a polymerizable compound, the logP of the polymerizable liquid crystal compound is preferably 1.0 or more, more preferably 3.0 or more, particularly preferably 5.0 or more, preferably 7.0 or less, more preferably 6.5 or less, particularly preferably 6.1 or less.

[0087] (Orientation aid)

[0088] The liquid crystal composition may contain an alignment aid as an optional component. The alignment aid is a compound that can improve the alignment of the liquid crystal compound when combined with the liquid crystal compound, and usually does not have liquid crystal properties. The alignment aid is preferably polymerizable, and therefore, is preferably a polymerizable compound.

[0089] As the alignment aid, for example, there can be mentioned a compound represented by the following formula (2).

[0090] R 1 -A 1 -BA 2 -R 2 (2)

[0091] In formula (2), R 1 and R 2 Each independently represents a group selected from a linear or branched alkyl group having 1 to 20 carbon atoms, a linear or branched oxyalkylene group having 1 to 20 carbon atoms, a hydrogen atom, a halogen atom, a hydroxyl group, a carboxyl group, a (meth)acryloyl group into which any bonding group may be inserted, an epoxy group, a mercapto group, an isocyanate group, an amino group, and a cyano group.

[0092] The alkyl group and the oxyalkylene group may be unsubstituted or substituted with one or more halogen atoms. Furthermore, the halogen atoms, hydroxyl group, carboxyl group, (meth)acryloyl group, epoxy group, mercapto group, isocyanate group, amino group, and cyano group may be bonded to the alkyl group and the oxyalkylene group having 1 to 2 carbon atoms.

[0093] As R 1 and R 2 Preferred examples of the group include a halogen atom, a hydroxyl group, a carboxyl group, a (meth)acryloyl group, an epoxy group, a mercapto group, an isocyanate group, an amino group, and a cyano group.

[0094] Preferred R 1 and R 2 At least one of is a reactive group. Furthermore, it is more preferred that R 1 and R 2 Both are reactive groups. Examples of the reactive group include a carboxyl group, a (meth)acryloyl group, an epoxy group, a mercapto group, an isocyanate group, and an amino group.

[0095] In formula (2), A 1 and A 2 Each independently represents a group selected from 1,4-phenylene, 1,4-cyclohexylene, cyclohexene-1,4-ene, 4,4'-biphenylene, 4,4'-bicyclohexylene, and 2,6-naphthylene. The above-mentioned 1,4-phenylene, 1,4-cyclohexylene, cyclohexene-1,4-ene, 4,4'-biphenylene, 4,4'-bicyclohexylene, and 2,6-naphthylene may be unsubstituted or substituted with one or more halogen atoms, hydroxyl groups, carboxyl groups, cyano groups, amino groups, alkyl groups having 1 to 10 carbon atoms, halogenated alkyl groups, etc. In A 1 and A 2 When two or more substituents are present in each of the above compounds, these substituents may be the same or different.

[0096] As A 1 and A 2 Particularly preferred groups include groups selected from 1,4-phenylene, 4,4'-biphenylene, and 2,6-naphthylene. These aromatic ring skeletons are more rigid than alicyclic skeletons, have a higher affinity with the mesogen of the rod-like liquid crystal compound, and can further improve the orientation uniformity.

[0097] In formula (2), B is selected from a single bond, -O-, -S-, -SS-, -CO-, -CS-, -OCO-, -CH2-, -OCH2-, -CH=NN=CH-, -NHCO-, -O-(C=O)-O-, -CH2-(C=O)-O-, and -CH2O-(C=O)-. As B, a single bond, -O-(C=O)-, and -CH=NN=CH- are particularly preferred.

[0098] As a particularly preferred specific example of the alignment aid represented by formula (2), the following compounds (A1) to (A10) can be cited. Among the following compounds (A1) to (A10), one or more selected from compounds (A2) and (A10) are particularly preferred. Compounds (A2) and (A10) can reduce the appearance temperature of the liquid crystal phase in the liquid crystal composition, and can maintain the temperature range of the liquid crystal phase of the liquid crystal compound in a wide range.

[0099] [Chemical formula 4]

[0100]

[0101] In the above compound (A3), "*" represents a chiral center.

[0102] The alignment aid may be used alone or in combination of two or more at any ratio.

[0103] The molecular weight of the orientation aid is preferably less than the molecular weight of the liquid crystal compound. For example, the molecular weight of the orientation aid is preferably less than 600, and the molecular weight of the liquid crystal compound is 600 or more. In this case, the fluidity of the liquid crystal composition is enhanced, and the uniformity of the orientation can be improved. The lower limit of the molecular weight of the orientation aid is not particularly limited, and is preferably 30 or more.

[0104] When the alignment aid is a polymerizable compound, the HSP of the polymerizable alignment aid is preferably 19 or more, more preferably 21 or more, particularly preferably 23 or more, and is preferably 29 or less, more preferably 27 or less, particularly preferably 25 or less.

[0105] When the alignment aid is a polymerizable compound, the logP of the polymerizable alignment aid is preferably 1.0 or more, more preferably 3.0 or more, particularly preferably 5.0 or more, and is preferably 7.0 or less, more preferably 6.5 or less, particularly preferably 6.1 or less.

[0106] The amount of the orientation aid is preferably adjusted to a weight ratio of the orientation aid to the liquid crystal compound (orientation aid / liquid crystal compound) in a specific range. Specifically, the range of the weight ratio (orientation aid / liquid crystal compound) is preferably 0.05 or more, more preferably 0.1 or more, particularly preferably 0.15 or more, preferably 1 or less, more preferably 0.65 or less, particularly preferably 0.55 or less. In the case where the above-mentioned weight ratio is above the lower limit of the above-mentioned range, the orientation uniformity of the liquid crystal composition can be improved. In addition, in the case where the above-mentioned weight ratio is below the upper limit of the above-mentioned range, the orientation uniformity of the liquid crystal composition and the stability of the liquid crystal phase can be improved.

[0107] (Chiral Agent)

[0108] The liquid crystal composition may contain a chiral agent as an optional component. The chiral agent may be polymerizable and thus may be a polymerizable compound.

[0109] Examples of chiral agents include those described in Japanese Patent Application Publication No. 2005-289881, Japanese Patent Application Publication No. 2004-115414, Japanese Patent Application Publication No. 2003-66214, Japanese Patent Application Publication No. 2003-313187, Japanese Patent Application Publication No. 2003-342219, Japanese Patent Application Publication No. 2000-290315, Japanese Patent Application Publication No. 6-072962, U.S. Patent No. 6468444, International Publication No. 98 / 00428, Japanese Patent Application Publication No. 2007-176870, etc. For example, LC756 of Paliocolor of BASF can be obtained as a chiral agent. The chiral agent can be used alone or in combination of two or more at any ratio.

[0110] The chiral agent preferably has chirality. By using a chiral agent with chirality, the circularly polarized light separation function of the cholesteric pigment can be improved. In addition, the twisting direction of the molecules with cholesteric regularity contained in the liquid crystal cured product can be selected according to the type and structure of the chiral agent.

[0111] When the chiral agent is a polymerizable compound, the HSP of the polymerizable chiral agent is preferably 19 or more, more preferably 21 or more, particularly preferably 23 or more, and is preferably 29 or less, more preferably 27 or less, particularly preferably 25 or less.

[0112] When the chiral agent is a polymerizable compound, the logP of the polymerizable chiral agent is preferably 1.0 or more, more preferably 3.0 or more, particularly preferably 5.0 or more, and is preferably 7.0 or less, more preferably 6.5 or less, particularly preferably 6.1 or less.

[0113] The amount of the chiral agent can be arbitrarily set within the range that does not reduce the desired optical properties. The specific amount of the chiral agent is preferably 0.0001 parts by weight or more, more preferably 0.01 parts by weight or more, particularly preferably 1 part by weight or more, preferably 50 parts by weight or less, more preferably 30 parts by weight or less, and particularly preferably 10 parts by weight or less, relative to 100 parts by weight of the liquid crystal compound.

[0114] (Surfactant)

[0115] The liquid crystal composition may contain a surfactant as an optional component. The surfactant can improve the orientation of the liquid crystal composition and improve the surface uniformity when forming a layer of the liquid crystal composition. The surfactant may be polymerizable and may be a polymerizable compound.

[0116] As the surfactant, nonionic surfactants containing siloxane or fluoroalkyl in the hydrophobic group part can be preferably cited. Among them, oligomers having more than two hydrophobic group parts in one molecule are particularly preferred. As specific examples of these surfactants, PF-151N, PF-636, PF-6320, PF-656, PF-6520, PF-3320, PF-651, PF-652 of PolyFox of OMNOVA can be cited; FTX-209F, FTX-208G, FTX-204D of FTERGENT of NEOS Co., Ltd.; KH-40, S420 of Surflon of AGC Qingmei Chemical Co., Ltd., etc. The surfactant can be used alone or in combination of two or more in any ratio.

[0117] Relative to 100 parts by weight of liquid crystal compounds, the amount of surfactant is preferably more than 0.01 parts by weight, more preferably more than 0.05 parts by weight, particularly preferably more than 0.10 parts by weight, preferably less than 0.50 parts by weight, more preferably less than 0.40 parts by weight, particularly preferably less than 0.30 parts by weight. In the case where the amount of surfactant is more than the lower limit of the above range, the orientation control force of the liquid crystal composition at the air interface can be improved, so the generation of orientation defects can be suppressed. In addition, in the case where the amount of surfactant is less than the upper limit of the above range, it is possible to suppress the formation of micellar structure by excessive surfactant, so that the surface state in the case of forming a layer of a liquid crystal composition can be good.

[0118] (Polymerization initiator)

[0119] The liquid crystal composition may contain a polymerization initiator as an optional component. As the polymerization initiator, a photopolymerization initiator is generally used. As the photopolymerization initiator, a compound that can generate free radicals or acids by ultraviolet light or visible light can be used.

[0120] Specific examples of the photopolymerization initiator include benzoin, benzyl dimethyl ketal, benzophenone, biacetyl, acetophenone, Michler's ketone, benzyl isobutyl ether, tetramethylthiuram mono(di)sulfide, 2,2-azobisisobutyronitrile, 2,2-azobis-2,4-dimethylvaleronitrile, benzoyl peroxide, di-tert-butyl peroxide, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propane-1-one, 1-(4-isopropyl)phenyl 2-Hydroxy-2-methylpropane-1-one, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-diethylthioxanthone, methyl benzoylformate, 2,2-diethoxyacetophenone, β-ionone, β-bromostyrene, diazoaminobenzene, α-amylcinnamaldehyde, p-dimethylaminoacetophenone, p-dimethylaminopropiophenone, 2-chlorobenzophenone, 4,4'-dichlorobenzophenone, 4,4'-bis(diethylaminobenzophenone), ethylbenzoin ether, benzoin isopropyl ether, benzoin n-propyl ether, benzoin n-butyl ether, diphenyl sulfide, bis(2,6-methoxybenzoyl)-2,4,4-trimethyl-pentylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2-methyl-1[4-(methylthio)phenyl]-2-morpholinopropane-1-one, 2-benzyl-2-dimethylamino-1-(4-morpholino phenyl)-butane-1-one, anthracene dibenzophenone, α-chloroanthraquinone, diphenyl disulfide, hexachlorobutadiene, pentachlorobutadiene, octachlorobutene, 1-chloromethylnaphthalene, 1,2-octanedione-1-[4-(phenylthio)-2-(o-benzoyl oxime)], 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazole-3-yl]ethanone-1-(o-acetyl oxime) and other carbazole oxime compounds, (4-methylphenyl)[4-(2-methylpropyl)phenyl]iodide Hexafluorophosphate, 3-methyl-2-butynyltetramethylene sulfide Hexafluoroantimonate, diphenyl-(p-phenylphenylthio)sulfide Hexafluoroantimonate, etc. The polymerization initiator may be used alone or in combination of two or more at any ratio. Furthermore, a known photosensitizer or a tertiary amine compound as a polymerization accelerator may be used as needed to control the curing property.

[0121] Relative to 100 parts by weight of liquid crystal compounds, the amount of the polymerization initiator is preferably more than 0.1 parts by weight, more preferably more than 0.5 parts by weight, particularly preferably more than 1 part by weight, preferably less than 30 parts by weight, more preferably less than 20 parts by weight, particularly preferably less than 10 parts by weight. In the case where the amount of the polymerization initiator is more than the lower limit of the above range, the degree of polymerization can be improved. In addition, in the case where the amount of the polymerization initiator is less than the upper limit of the above range, the orientation of the liquid crystal compound can be made good, so the liquid crystal phase of the liquid crystal composition can be stabilized.

[0122] (Other optional ingredients)

[0123] The liquid crystal composition can further include other arbitrary components as needed. As arbitrary components, for example: a crosslinking agent; an inhibitor for improving the pot life; an antioxidant, an ultraviolet absorber, and a light stabilizer for improving durability. These arbitrary components can be used alone or in combination of two or more in any ratio. The amount of these arbitrary components can be arbitrarily set within the range that does not reduce the desired optical properties. For these arbitrary components, reference can be made to International Publication No. 2016 / 002765.

[0124] (Polymerizable compound)

[0125] The liquid crystal composition contains one or more polymerizable compounds. The polymerizable compound contained in the liquid crystal composition can be a non-volatile component that cannot be removed by drying when the liquid crystal composition is cured. Therefore, the polymerizable compound or its polymer can remain in the liquid crystal cured product obtained by curing the liquid crystal composition. The non-volatile component usually has a high boiling point, for example, it can have a boiling point of 230° C. or more in an atmospheric pressure environment.

[0126] The polymerizable compound contained in the liquid crystal composition can have a weighted average HSP that satisfies the above-mentioned necessary condition (i) between the HSP of the stabilizer and the weighted average HSP of the polymerizable compound. The weighted average HSP of the polymerizable compound represents the weighted average of the HSP of the polymerizable compound contained in the liquid crystal composition based on weight. Therefore, for example, in the case where a certain liquid crystal composition contains three polymerizable compounds having HSPs of h1, h2 and h3 by weights m1, m2 and m3, the weighted average HSP of the polymerizable compounds contained in the liquid crystal composition can be obtained by "{(h1×m1)+(h2×m2)+(h3×m3)} / (m1+m2+m3)".

[0127] The range of the weighted average HSP of the polymerizable compound contained in the liquid crystal composition is not particularly limited as long as the effect of the present invention can be obtained, but is preferably 21 or more, more preferably 22 or more, particularly preferably 23 or more, preferably 26 or less, more preferably 25 or less, and particularly preferably 24 or less.

[0128] The polymerizable compound contained in the liquid crystal composition can have a weighted average logP that satisfies the above-mentioned necessary condition (ii) between the logP of the stabilizer and the weighted average logP of the polymerizable compound. The weighted average logP of the polymerizable compound represents the weighted average of the logP of the polymerizable compound contained in the liquid crystal composition based on weight. Therefore, for example, in the case where a certain liquid crystal composition contains three polymerizable compounds having logPs of L1, L2 and L3 by weights m1, m2 and m3, the weighted average logP of the polymerizable compound contained in the liquid crystal composition can be obtained by "{(L1×m1)+(L2×m2)+(L3×m3)} / (m1+m2+m3)".

[0129] The range of the weighted average logP of the polymerizable compound contained in the liquid crystal composition is not particularly limited as long as the effect of the present invention can be obtained, but is preferably 3.0 or more, more preferably 4.0 or more, particularly preferably 5.0 or more, and preferably 6.5 or less, more preferably 6.0 or less, particularly preferably 5.5 or less.

[0130] The polymerizable compound preferably contains the main component of the non-volatile component contained in the liquid crystal composition. Hereinafter, the polymerizable compound that is the main component of the non-volatile component contained in the liquid crystal composition is sometimes referred to as the "main component monomer". Unless otherwise specified, the main component monomer represents the compound with the largest amount among the non-volatile components contained in the liquid crystal composition. Relative to 100% by weight of the non-volatile component of the liquid crystal composition, the amount of the main component monomer contained in the liquid crystal composition is preferably 50% by weight or more, more preferably 60% by weight or more, and particularly preferably 70% by weight or more. In the case where the polymerizable compound contains the above-mentioned main component monomer, the change in the wavelength of the circularly polarized light that the cholesteric pigment can reflect in a high temperature and high humidity environment can be effectively suppressed. The upper limit of the amount of the main component monomer contained in the liquid crystal composition is not particularly limited, and is usually 100% by weight or less.

[0131] The main component monomer is preferably a liquid crystal compound. When the main component monomer is a liquid crystal compound, the change in the wavelength of the circularly polarized light that the cholesteric pigment can reflect in a high temperature and high humidity environment can be effectively suppressed. In particular, the main component monomer is more preferably the above-mentioned rod-shaped liquid crystal compound, and is further preferably a liquid crystal compound represented by the above formula (X1). In addition, in the case where the polymerizable compound includes a liquid crystal compound, the polymerizable compound other than the liquid crystal compound is preferably capable of reacting and bonding with the liquid crystal compound when the liquid crystal composition is cured. Therefore, the polymerizable compound is preferably selected from a polymerizable liquid crystal compound and a compound capable of reacting and bonding with the liquid crystal compound.

[0132] (Characteristics of cholesteric pigments)

[0133] By including a liquid crystal cured product as a cured product of the above-mentioned liquid crystal composition, the cholesteric pigment can selectively reflect circularly polarized light of one rotation direction in the selective reflection wavelength range and transmit circularly polarized light of the opposite rotation direction. Since the wavelength width of the selective reflection wavelength range of the cholesteric pigment is high in visual recognition when it is wide, it is preferably 50nm or more, more preferably 60nm or more, and particularly preferably 70nm or more. In addition, from the sense of being able to reflect a wide visible light wavelength range with a thin cholesteric pigment, it is preferably 500nm or less, more preferably 400nm or less, and particularly preferably 300nm or less.

[0134] From the viewpoint of being able to be visually recognized with the naked eye, the selective reflection wavelength range is preferably in the visible light wavelength range. That is, the cholesteric pigment preferably has a circularly polarized light separation function in the visible light wavelength range. The visible light wavelength region generally refers to a wavelength range of more than 400nm and less than 780nm. In addition, the selective reflection wavelength range of the cholesteric pigment can include the entirety of the visible light wavelength range.

[0135] The specific wavelength that exerts the circularly polarized light separation function usually depends on the pitch of the helical structure in the liquid crystal cured product contained in the cholesteric pigment. The pitch of the helical structure represents: in the helical structure, the direction of the molecular axis gradually shifts as it advances on the plane, and then the distance in the plane normal direction until it returns to the original molecular axis direction again. Therefore, by changing the size of the pitch of the helical structure, the wavelength that exerts the circularly polarized light separation function can be changed. As a method for adjusting the pitch, the method described in Japanese Patent Gazette No. 2009-300662 can be used, for example. When giving a specific example, a method for adjusting the type of chiral agent or the amount of chiral agent in the liquid crystal composition can be cited. In particular, when the size of the pitch of the helical structure changes continuously in the layer, a circularly polarized light separation function over a wide wavelength range can be obtained by a single layer of liquid crystal cured product.

[0136] Cholesteric pigments that can perform circularly polarized light separation functions in a wide wavelength range can be realized by, for example, a layer of a liquid crystal cured material whose pitch of the spiral structure changes in stages. A layer of a liquid crystal cured material whose pitch of the spiral structure changes in stages can be obtained by, for example, stacking a plurality of layers of liquid crystal cured materials having different pitches of the spiral structure. The stacking can be performed by pre-fabricating a plurality of layers of liquid crystal cured materials having different pitches of the spiral structure, and then bonding the layers together with an adhesive or a binder. Alternatively, the stacking can be performed by gradually forming other layers of liquid crystal cured materials in sequence on the basis of forming a layer of a certain liquid crystal cured material.

[0137] In addition, cholesteric pigments that can exert circularly polarized light separation function in a wide wavelength range can be realized by, for example, a layer of a liquid crystal cured material in which the size of the pitch of the spiral structure changes continuously. The layer of a liquid crystal cured material in which the size of the pitch of the spiral structure changes continuously can be obtained by, for example, curing the layer of the liquid crystal composition after subjecting the layer of the liquid crystal composition to a broadband treatment including one or more active energy ray irradiation treatment and / or heat treatment. Through the above-mentioned broadband treatment, the pitch of the spiral structure can be continuously changed in the thickness direction, so that the wavelength range (reflection band) in which the layer of the liquid crystal cured material can exert the circularly polarized light separation function can be expanded, and therefore it is called broadband treatment.

[0138] The layer of the liquid crystal cured material may be a single-layer structure consisting of only one layer or a multilayer structure layer including two or more layers. From the viewpoint of easy production, the number of layers of the liquid crystal cured material is preferably 1 to 100, more preferably 1 to 20.

[0139] The thickness of the layer of the liquid crystal solidified material is preferably 2 μm or more, more preferably 3 μm or more, preferably 1000 μm or less, and more preferably 500 μm or less. When the thickness of the layer of the liquid crystal solidified material is above the lower limit of the above range, the reflectivity of the cholesteric pigment to one of the right-handed circularly polarized light and the left-handed circularly polarized light can be increased. On the other hand, when the thickness of the layer of the liquid crystal solidified material is below the upper limit of the above range, the transmittance of the other of the right-handed circularly polarized light and the left-handed circularly polarized light can be increased, and the transparency of the cholesteric pigment when observed through an appropriate circular polarizer can be improved.

[0140] The cholesteric pigment may include any element in combination with the liquid crystal cured product as required. For example, the cholesteric pigment may include a protective layer covering the liquid crystal cured product.

[0141] Cholesteric pigments are usually granular, and are particularly preferably in the form of small flakes. Usually, due to the shear force applied when forming the display layer, the main surface of the small flake-shaped cholesteric pigment is oriented in a parallel or nearly parallel manner to the layer plane of the display layer containing the cholesteric pigment. Therefore, the cholesteric pigment can effectively receive the light entering the display layer, so it can effectively reflect circularly polarized light, and thus the visual recognition of the cholesteric pigment can be improved.

[0142] The flake-shaped cholesteric pigment preferably has a large aspect ratio. The aspect ratio of the cholesteric pigment is obtained by dividing the average particle size of the cholesteric pigment by the thickness of the cholesteric pigment. The specific aspect ratio of the cholesteric pigment is preferably 3 or more, more preferably 5 or more, particularly preferably 10 or more, preferably 40 or less, more preferably 30 or less, and particularly preferably 20 or less.

[0143] The thickness of the cholesteric pigment can be appropriately set so as to obtain the desired optical properties. Specifically, the thickness of the cholesteric pigment is preferably 1 μm or more, more preferably 2 μm or more, particularly preferably 3 μm or more, and preferably 20 μm or less, more preferably 10 μm or less, particularly preferably 5 μm or less.

[0144] The average particle size of the cholesteric pigment is preferably 30 μm or more, more preferably 40 μm or more, particularly preferably 50 μm or more, and preferably 150 μm or less, more preferably 120 μm or less, and particularly preferably 100 μm or less. When the average particle size of the cholesteric pigment is greater than the lower limit of the above range, the visual recognition of the cholesteric pigment can be particularly effectively improved. In addition, when the average particle size of the cholesteric pigment is less than the upper limit of the above range, the coating property or printing adaptability of the ink composition can be improved.

[0145] The average particle size of the cholesteric pigment is preferably greater than the thickness of the display layer formed using the ink composition. In this case, the flake-shaped cholesteric pigment is easily oriented so that the main surface of the cholesteric pigment is parallel to or at an acute angle to the layer plane of the display layer. Therefore, the cholesteric pigment can effectively receive light entering the display layer, so the visual recognition of the cholesteric pigment can be improved.

[0146] The average particle size of the cholesteric pigment can be measured by a laser diffraction / scattering particle size analyzer ("Laser Micron Sizer LMS-3000" manufactured by Seishin Enterprise Co., Ltd.). The average particle size can be the median diameter D50 at which the cumulative volume is 50% in the particle size distribution measured using the particle size analyzer.

[0147] Cholesteric pigments can be produced by, for example, a manufacturing method comprising a step of forming a liquid crystal solidified material and a step of crushing the liquid crystal solidified material. Among them, in the case of manufacturing flaky cholesteric pigments, a manufacturing method comprising a step of forming a layer of a liquid crystal solidified material and a step of crushing the layer of the liquid crystal solidified material is preferably used.

[0148] There is no restriction on the manufacturing method of liquid crystal cured material. Liquid crystal cured material can be manufactured by, for example, sequentially including a process of orienting the liquid crystal compound contained in the liquid crystal composition and a process of curing the liquid crystal composition. In addition, in the case of forming a layer of liquid crystal cured material, the manufacturing method of liquid crystal cured material can include a process of coating the liquid crystal composition on a suitable supporting surface to form a layer of the liquid crystal composition before the process of orienting the liquid crystal compound. As a specific method for manufacturing liquid crystal cured material, for example, the method described in Japanese Patent Publication No. 2014-174471 and Japanese Patent Publication No. 2015-27743 can be cited.

[0149] After manufacturing the liquid crystal solidified material, the liquid crystal solidified material is crushed to obtain a cholesteric pigment containing the liquid crystal solidified material. In addition, the method for manufacturing the cholesteric pigment may further include any steps, for example, the step of classifying the cholesteric pigment after crushing. As the method for manufacturing the cholesteric pigment, for example, the method described in Japanese Patent Gazette No. 6142714 may be used.

[0150] (Amount of cholesteric pigment)

[0151] The amount of the cholesteric pigment contained in the ink composition is preferably 3 wt % or more, more preferably 5 wt % or more, further preferably 10 wt % or more, preferably 40 wt % or less, more preferably 30 wt % or less, and particularly preferably 20 wt % or less, relative to 100 wt % of the ink composition.

[0152] [3. Stabilizer (non-volatile organic compound)]

[0153] The stabilizer is a non-volatile organic compound that satisfies at least one of the above-mentioned requirements (i) and (ii). Here, the organic compound as the stabilizer is "non-volatile" which means that when the display layer is formed using the ink composition, the organic compound cannot be removed by drying but can remain in the display layer. Such a non-volatile stabilizer generally has a high boiling point, for example, a boiling point of 230° C. or more in an atmospheric pressure environment.

[0154] The necessary condition (i) that the stabilizer should satisfy is described in detail. The liquid crystal composition as a raw material of the liquid crystal cured product contained in the cholesteric pigment contains a polymerizable compound, and the absolute value of the difference between the weighted average HSP of the above-mentioned polymerizable compound and the HSP of the stabilizer |ΔHSP1| is usually greater than 0.0, usually less than 3.0, preferably less than 2.0, more preferably less than 1.5, further preferably less than 1.0, and particularly preferably less than 0.5.

[0155] The weighted average HSP of the polymerizable compound included in the liquid crystal composition is represented by "HSP(ave)". In addition, the HSP of the stabilizer is represented by "HSP(b)". In this case, the difference between the weighted average HSP of the polymerizable compound and the HSP of the stabilizer is represented by "HSP(ave)-HSP(b)", and the absolute value of the difference |ΔHSP1| is represented by "|HSP(ave)-HSP(b)|".

[0156] Next, the necessary condition (ii) that the stabilizer should satisfy is described in detail. The liquid crystal composition as a raw material of the liquid crystal cured product contained in the cholesteric pigment contains a polymerizable compound, and the absolute value of the difference between the weighted average logP of the polymerizable compound and the logP of the stabilizer |ΔlogP1| is usually greater than 0.0, usually less than 1.0, and preferably less than 0.5.

[0157] The weighted average logP of the polymerizable compound contained in the liquid crystal composition is represented by "logP(ave)". In addition, the logP of the stabilizer is represented by "logP(b)". In this case, the difference between the weighted average logP of the polymerizable compound and the logP of the stabilizer is represented by "logP(ave)-logP(b)", and the absolute value of the difference |ΔlogP1| is represented by "|logP(ave)-logP(b)|".

[0158] The stabilizer may satisfy one of the above-mentioned requirements (i) and (ii), preferably both. When a stabilizer that satisfies both requirements (i) and (ii) is used, the change in the wavelength of circularly polarized light that the cholesteric pigment can reflect in a high temperature and high humidity environment can be effectively suppressed.

[0159] Furthermore, the square root of the sum of the squares of the absolute value |ΔHSP1| and the absolute value |ΔlogP1| {|ΔHSP1| 2 +|ΔlogP1| 2} 1 / 2 Preferably, it is within a specific range. Specifically, the square root of the sum of squares {|ΔHSP1| 2 +|ΔlogP1| 2} 1 / 2 It is preferably 5.0 or less, more preferably 1.5 or less, and usually 0.0 or more. 2 +|ΔlogP1| 2} 1 / 2 In the case of the above range, it is possible to effectively suppress the change in the wavelength of circularly polarized light that can be reflected by the cholesteric pigment in a high-temperature and high-humidity environment.

[0160] The stabilizer is preferably a compound identical to the compound contained in the liquid crystal composition as the raw material of the liquid crystal cured product contained in the cholesteric pigment. That is, it is preferred that the liquid crystal composition contains the same compound as the stabilizer. Among them, the stabilizer is more preferably a compound identical to the polymerizable compound contained in the liquid crystal composition. That is, it is more preferred that the polymerizable compound of the liquid crystal composition contains the same compound as the stabilizer. Furthermore, the stabilizer is particularly preferably a compound identical to the main component monomer. In this case, the change in the wavelength of the circularly polarized light that the cholesteric pigment can reflect in a high temperature and high humidity environment can be effectively suppressed.

[0161] The stabilizer is preferably a liquid crystal compound. In this case, it is possible to effectively suppress changes in the wavelength of circularly polarized light that the cholesteric pigment can reflect in a high temperature and high humidity environment.

[0162] The amount of the stabilizer is preferably 0.5 parts by weight or more, more preferably 1.0 parts by weight or more, particularly preferably 1.5 parts by weight or more, preferably 10 parts by weight or less, more preferably 5 parts by weight or less, particularly preferably 3 parts by weight or less, relative to 100 parts by weight of the cholesteric pigment. When the amount of the stabilizer is within the above range, the change in the wavelength of the circularly polarized light that the cholesteric pigment can reflect in a high temperature and high humidity environment can be effectively suppressed.

[0163] [4. Organic solvents]

[0164] The ink composition of one embodiment of the present invention preferably contains an organic solvent as an arbitrary component. The organic solvent can improve the fluidity of the ink composition, improve the coating property and printing adaptability. In the ink composition containing an organic solvent, the cholesteric pigment is usually dispersed in the organic solvent. In addition, the stabilizer is usually dissolved or dispersed in the organic solvent. The organic solvent is usually volatile, so the display layer formed by the ink composition does not contain an organic solvent, or even if it contains an organic solvent, its amount is small.

[0165] Examples of the organic solvent include ketone compounds, alkyl halide compounds, amide compounds, sulfoxide compounds, heterocyclic compounds, hydrocarbon compounds, ester compounds, and ether compounds. The organic solvent may be used alone or in combination of two or more at any ratio.

[0166] It is preferred that the organic solvent contains a diluent. The diluent refers to an organic solvent that satisfies the following requirement (iii).

[0167] Requirement (iii): The liquid crystal composition as a raw material of the liquid crystal cured product containing the cholesteric pigment contains a polymerizable compound, and the absolute value of the difference between the weighted average HSP of the polymerizable compound and the HSP of the diluent |ΔHSP2| is greater than 2.

[0168] The necessary condition (iii) that the diluent should satisfy is described in detail: The absolute value of the difference between the weighted average HSP of the polymerizable compound and the HSP of the diluent |ΔHSP2| is preferably large, usually greater than 2.0, preferably greater than 3.0, and particularly preferably greater than 5.0.

[0169] The liquid crystal composition as a raw material of the liquid crystal cured product containing the cholesteric pigment contains a polymerizable compound, and the weighted average HSP of the above-mentioned polymerizable compound is represented by "HSP(ave)". In addition, the HSP of the diluent is represented by "HSP(c)". In this case, the difference between the weighted average HSP of the polymerizable compound and the HSP of the diluent is represented by "HSP(ave)-HSP(c)", and the absolute value of the difference |ΔHSP2| is represented by "|HSP(ave)-HSP(c)|".

[0170] In the case where the ink composition includes a diluent, the change in the wavelength of the circularly polarized light that the cholesteric pigment can reflect caused by the preparation of the ink composition and the formation of the display layer can be suppressed. The details are as follows. Generally, the wavelength of the circularly polarized light that the cholesteric pigment can reflect can be changed by mixing with the components other than the cholesteric pigment contained in the ink composition. This change may cause an undesirable change in the color of the display layer. In contrast, when a diluent that satisfies the necessary condition (iii) is used, the above-mentioned change can be suppressed.

[0171] The HSP of the diluent is preferably 26.0 or more, more preferably 26.5 or more. The upper limit of the HSP of the diluent can be, for example, 47 or less. In addition, the HSP of the diluent is preferably 18 or less, more preferably 17.5 or less, and particularly preferably 17.0 or less. The lower limit of the HSP of the diluent can be, for example, 15.0 or more. When a diluent having an HSP in such a range is used, changes in the wavelength of circularly polarized light that can be reflected by the cholesteric pigment caused by the preparation of the ink composition and the formation of the display layer can be effectively suppressed.

[0172] The amount of the organic solvent contained in the ink composition is preferably 40 parts by weight or more, more preferably 60 parts by weight or more, and particularly preferably 80 parts by weight or more, relative to 100 parts by weight of the cholesteric pigment, and is preferably 1000 parts by weight or less, more preferably 800 parts by weight or less, and particularly preferably 600 parts by weight or less. When the amount of the organic solvent is within the above range, the coating property of the ink composition can be improved.

[0173] In the case where the organic solvent contains a diluent, the amount of the diluent contained in the ink composition is preferably 30 parts by weight or more, more preferably 50 parts by weight or more, particularly preferably 100 parts by weight or more, preferably 500 parts by weight or less, more preferably 300 parts by weight or less, particularly preferably 200 parts by weight or less, relative to 100 parts by weight of the cholesteric pigment. When the amount of the diluent is within the above range, changes in the wavelength of circularly polarized light that the cholesteric pigment can reflect due to the preparation of the ink composition and the formation of the display layer can be effectively suppressed.

[0174] [5. Adhesive]

[0175] The ink composition of one embodiment of the present invention may contain a binder for bonding the cholesteric pigment in the display layer as an arbitrary component. As the binder, a polymer is generally used. Examples of the polymer include polyester polymers, acrylic polymers, polystyrene polymers, polyamide polymers, polyurethane polymers, polyolefin polymers, polycarbonate polymers, polyethylene polymers, etc. The binder may be used alone or in combination of two or more at any ratio.

[0176] The amount of the binder is preferably 50 parts by weight or more, more preferably 100 parts by weight or more, particularly preferably 200 parts by weight or more, and preferably 1000 parts by weight or less, more preferably 800 parts by weight or less, particularly preferably 700 parts by weight or less, relative to 100 parts by weight of the cholesteric pigment. When the amount of the binder is within the above range, the coating property of the ink composition can be improved, and the cholesteric pigment can be stably bonded.

[0177] The ink composition may contain a monomer of a polymer as a binder instead of the polymer or in combination with the polymer. In this case, by applying the ink composition and polymerizing the monomer after drying, the cholesteric pigment can be bound by the binder. Furthermore, the ink composition containing the monomer preferably further contains a polymerization initiator.

[0178] [6. Other optional ingredients]

[0179] In addition to the above-mentioned components, the ink composition of one embodiment of the present invention may further include any component. Examples of these optional components include antioxidants, ultraviolet absorbers, light stabilizers, bluing agents, etc. These may be used alone or in combination of two or more in any ratio.

[0180] [7. Physical properties of ink composition]

[0181] The ink composition of one embodiment of the present invention can be a fluid material. Here, the fluid state includes not only a low-viscosity liquid state but also a high-viscosity gel state. The specific viscosity of the ink composition can be appropriately adjusted according to the use of the ink composition.

[0182] [8. Usage and Effects of Ink Composition]

[0183] The ink composition of one embodiment of the present invention is used to form a display layer. For example, the ink composition can be applied to an appropriate member and cured by drying or other methods as needed to form a display layer. The formed display layer can include a cholesteric pigment and a stabilizer. Since the cholesteric pigment can selectively reflect circularly polarized light in a selective reflection wavelength range, the display layer including the cholesteric pigment can also perform the same circularly polarized light separation function as the cholesteric pigment. Therefore, the display layer can be visually recognized as a layer of a color corresponding to the selective reflection wavelength range.

[0184] Since the ink composition includes a stabilizer and a cholesteric pigment in combination, the change in the wavelength of circularly polarized light that can be reflected by the cholesteric pigment contained in the display layer manufactured by the ink composition can be suppressed in a high temperature and high humidity environment. For example, when the display layer is stored in a high temperature and high humidity environment at a temperature of 90°C and a humidity of 80%RH, the change in the central wavelength of the selective reflection range (color shift) can be suppressed. Therefore, the change in the undesired color of the display layer in a high temperature and high humidity environment can be suppressed.

[0185] For example, when a display layer formed by printing an ink composition by the method described in the examples below is subjected to a durability test in an environment of 90°C and 80%RH for 14 days, the change in the selective reflection wavelength range of the cholesteric pigment contained in the display layer can be reduced. Specifically, it is preferred that the change be 15 nm or less, more preferably 10 nm or less, and particularly preferably 5 nm or less. The lower limit of the change is usually 0 nm.

[0186] The present inventors believe that the mechanism by which the ink composition according to one embodiment of the present invention can exert the above-mentioned effects is as follows. However, the technical scope of the present invention is not limited to the following mechanism.

[0187] When the liquid crystal composition is cured, a part or all of the polymerizable compound undergoes polymerization and cross-linking reactions to bond to obtain a liquid crystal cured product. Therefore, the liquid crystal cured product contains a polymer of the polymerizable compound and can also contain unreacted polymerizable compounds. In addition, in the liquid crystal cured product contained in the cholesteric pigment, a part or all of the polymerizable compound and its polymer are oriented in a manner having cholesteric regularity. Generally, the molecules of the polymer are subject to constraints caused by bonds, while the unreacted polymerizable compound is not subject to constraints caused by bonds. Therefore, the molecules of a part of the unpolymerized polymerizable compound can move.

[0188] For example, some molecules of the polymerizable compound may move from the position that the molecules oriented in the helical structure corresponding to cholesteric regularity should occupy, and the molecules occupying the above position disappear to generate a vacancy. In this case, only the pitch of the partial helical structure at the vacant position can change.

[0189] In addition, for example, there may be a situation where the molecules that are not oriented with cholesteric regularity move, and as a result, the pitch of the helical structure of the molecules oriented in a manner with cholesteric regularity changes. When giving a specific example, the following situation can be considered: the molecules (molecules that are not oriented with cholesteric regularity) in the gap position between the molecules oriented in a manner with a helical structure move, and a vacancy is generated in the above-mentioned gap position. In this case, the helical structure changes in a manner that fills the above-mentioned vacant position, and as a result, the pitch of the helical structure can change.

[0190] When the pitch of the cholesteric regular helical structure changes, the wavelength of circularly polarized light that can be reflected by the liquid crystal cured product changes, so the wavelength of circularly polarized light that can be reflected by the cholesteric pigment can also change. In a high temperature and high humidity environment, unpolymerized polymerizable compounds tend to move easily and dissolve out of the liquid crystal cured product, so in the past, the wavelength of circularly polarized light that can be reflected by cholesteric pigments in a high temperature and high humidity environment can change significantly.

[0191] In contrast, the ink composition of the present embodiment includes a stabilizer having an HSP or logP close to the weighted average HSP or weighted average logP of the polymerizable compound. The display layer obtained by the ink composition includes the above-mentioned stabilizer and a cholesteric pigment combination. The stabilizer has an easy solubility close to the polymerizable compound. Therefore, through the dissolution equilibrium, the polymerizable compound can be suppressed from being dissolved from the liquid crystal cured product contained in the cholesteric pigment, so that the pitch of the cholesteric regular spiral structure can be made less likely to change. In addition, assuming that a part of the molecules of the polymerizable compound is dissolved and a vacancy is generated in the spiral structure or its surrounding position, the molecules of the stabilizer can easily fill the vacant position. Therefore, even if the pitch of the spiral structure changes, its change amount can be reduced. Therefore, the change in the wavelength of the circularly polarized light that the liquid crystal cured product can reflect can be suppressed, so the change in the wavelength of the circularly polarized light that the cholesteric pigment containing the liquid crystal cured product can be suppressed.

[0192] The display layer can be formed by a method including the step of coating an ink composition on the surface of a component having a surface on which the display layer is to be formed. The coating method is not limited, and a printing method is preferred. In addition, the method for forming the display layer may also include a step of curing the coated ink composition. For example, in the case where the ink composition contains an organic solvent, the organic solvent is removed by drying, thereby curing the ink composition to obtain a display layer. In addition, in the case where the ink composition contains a monomer equivalent to a binder, the method for forming the display layer may also include a step of polymerizing the above-mentioned monomer and curing the ink composition.

[0193] [9. Article having a display layer formed of an ink composition]

[0194] The ink composition can be used, for example, to manufacture an article having a display layer. The article comprises a member having a surface and a display layer formed on the surface of the member. The display layer is formed by the ink composition and therefore contains a cholesteric pigment and a stabilizer. Therefore, the display layer can exert a circularly polarized light separation function of selectively reflecting circularly polarized light in a selectively reflected wavelength range. Moreover, the change in the wavelength of the circularly polarized light reflected in this way in a high temperature and high humidity environment can be suppressed.

[0195] The member forming the display layer is not limited, and a wide range of members can be used. Examples of the member include: cloth products such as clothing; leather products such as bags and shoes; metal products such as screws; paper products such as price tags; and rubber products such as tires, but the member is not limited to these examples.

[0196] The display layer can be formed into a layer having any planar shape. The planar shape refers to the shape of the display layer observed from the thickness direction. In order to give design or information, the planar shape of the display layer can be a picture, text, number, symbol, identifier (barcode, etc.), etc.

[0197] The article can be produced by a production method including, for example, a step of applying an ink composition on a surface of a member. In addition, the production method of the article may include a step of curing the applied ink composition after applying the ink composition.

[0198] The display layer of the above-mentioned article can be used as a security display layer for anti-counterfeiting, for example. For example, due to its cholesteric regularity, the visually recognized reflected color of the cholesteric pigment can change according to the observation angle (especially the incident angle). Therefore, if the color of the cholesteric pigment changes according to the observation angle when observing the display layer, it can be judged that the article is authentic.

[0199] In addition, for example, since the cholesteric pigment can selectively reflect circularly polarized light in only one direction of right-handed and left-handed, the image visually recognized through the right-handed circular polarizer and the image visually recognized through the left-handed circular polarizer can be different. Therefore, if the image visually recognized through the right-handed circular polarizer and the image visually recognized through the left-handed circular polarizer are different, it can be determined that the article having the display layer is authentic.

[0200] Furthermore, the circularly polarized light separation function of the cholesteric pigment can be used to produce an article as a display medium for realizing a new display method.

[0201] Example

[0202] The present invention will be described in detail below with reference to the following embodiments. However, the present invention is not limited to the following embodiments, and can be arbitrarily modified within the scope of the claims and their equivalents.

[0203] In the following description, "%" and "parts" indicating amounts are based on weight unless otherwise specified. In addition, the following operations are performed in an atmosphere of normal temperature and pressure unless otherwise specified.

[0204] [Calculation method of HSP value]

[0205] HSP value refers to Hildebrand solubility parameter. The HSP value is calculated by the Y-MB method of SP value calculation software "HSPiP version 4.1.7" (https: / / pirika.com / NewHP / Y-MB / Y-MB.html).

[0206] [Method for determining logP value]

[0207] A sample solution containing 1 wt% of the sample compound is prepared, and tetrahydrofuran or acetonitrile is used as a solvent for the sample solution.

[0208] The above solution was subjected to HPLC / ELSD analysis by a method substantially in accordance with JIS 7260-117:2006 (Determination of partition coefficient (1-octanol / water) - High performance liquid chromatography) under the following HPLC / ELSD analysis conditions, and the elution time (rt) was measured.

[0209] (HPLC / ELSD analysis conditions)

[0210] LC system: LC-20A (manufactured by Shimadzu Corporation)

[0211] Chromatographic column: Inertsil ODS-3 3.0×150 mm, 5 μm (manufactured by GL Sciences Co., Ltd.)

[0212] Mobile phase: A water

[0213] B Acetonitrile / tetrahydrofuran = 8 / 2 (volume / volume)

[0214] Acetonitrile: Made in China for HPLC

[0215] Tetrahydrofuran: inhibitor-free, for HPLC, manufactured by SIGMA-ALDRICH

[0216] Time program: from 0 minutes to 15 minutes B from 30% to 100%

[0217] From 15 minutes to 25 minutes B100%

[0218] Column temperature: 45°C

[0219] Flow rate: 0.8mL / min

[0220] Injection volume: 10 μL (adjust to 50 μL or 100 μL if the detection sensitivity of the sample is low)

[0221] Detection: ELSD-LTII (Shimadzu Corporation) Gain6, 350kPa, 65℃

[0222] (Export of standard curve)

[0223] Prepare standard compounds (triphenylamine, phenanthrene, benzyl benzoate and acetanilide) with known logP values ​​as described in JIS 7260-117:2006. Each standard compound is a commercially available reagent and is used directly without purification. Dissolve 0.1 g of each standard compound in 10 mL of tetrahydrofuran (inhibitor-free, for HPLC SIGMA-ALDRICH) to prepare a sample solution. Perform HPLC / ELSD analysis of the obtained sample solution under the analysis conditions described in the above (HPLC / ELSD analysis conditions) and measure the elution time (rt). The temperature of the ELSD detector is set to 25°C.

[0224] Triphenylamine (produced by Kanto Chemical Co., Ltd., deer grade, CAS = 603-34-9, logP = 5.7, boiling point = 348°C): rt = 16.0 minutes, injection = 10 μL

[0225] Phenanthrene (Kanto Chemical Co., Ltd., deer grade 1, CAS = 85-01-8, logP = 4.5, boiling point = 375°C): rt = 13.6 minutes, injection = 50 μL

[0226] Benzyl benzoate (Kanto Chemical Co., Ltd., deer grade, CAS = 120-51-4, logP = 4.0, boiling point = 323°C): rt = 12.4 minutes, injection = 10 μL

[0227] Acetanilide (Kanto Chemical Co., Ltd., Deer Grade 1, CAS = 103-84-4, logP = 1.0, boiling point = 184°C): rt = 3.0 min, injection = 10 μL

[0228] The analysis results of the above standard compounds were plotted in a coordinate system with elution time (rt) as the horizontal axis and logP as the vertical axis, and an approximate straight line was prepared by the least square method. The approximate straight line was used as the standard curve. The above standard curve is shown in Figure 1 .

[0229] (Calculation of logP value of sample compound)

[0230] The logP value of the sample compound is obtained by substituting the elution time (rt) obtained for each sample compound into the above-mentioned standard curve. In HPLC / ELSD analysis, when multiple peaks representing elution time (rt) are detected for each sample compound, the peak top of the peak with the largest area is used as the elution time (rt) of the sample compound to obtain the logP value.

[0231] [Measurement method of reflectivity]

[0232] The reflectance when non-polarized light (wavelength: 300 nm to 950 nm) was incident was measured using an ultraviolet-visible spectrophotometer ("UV-Vis 770" manufactured by JASCO Corporation) using an integrating sphere.

[0233] [Production Example 1: Production of a Solution (G) Containing a Cholesteric Liquid Crystal Composition Capable of Reflecting Green Right-Handed Circularly Polarized Light]

[0234] 100 parts of a photopolymerizable liquid crystal compound represented by the following formula (X1) (HSP=24.4, logP=6.01), 25 parts of a photopolymerizable non-liquid crystal compound represented by the following formula (X2) (HSP=20.9, logP=1.75), 8.1 parts of a polymerizable chiral agent ("LC756" manufactured by BASF; HSP=22.8, logP=3.58), 4.1 parts of a photopolymerization initiator ("N-1919T" manufactured by ADICO Corporation), 0.17 parts of a surfactant ("S-420" manufactured by AGC Seimi Chemical Co., Ltd.), 120 parts of cyclopentanone as a solvent, and 200 parts of dioxolane were mixed to prepare a solution (G) containing a cholesteric liquid crystal composition capable of reflecting right-handed circularly polarized light of green. The weighted average HSP and weighted average logP of the polymerizable compound of the cholesteric liquid crystal composition contained in the solution (G) are as follows.

[0235] Weighted average HSP = (24.4 × 100 + 20.g × 25 + 22.8 × 8.1) ÷ (100 + 25 + 8.1) ≈ 23.65

[0236] Weighted average logP = (6.01 × 100 + 1.75 × 25 + 3.58 × 8.1) ÷ (100 + 25 + 8.1) ≈ 5.06

[0237] [Chemical formula 5]

[0238]

[0239] [Chemical formula 6]

[0240]

[0241] [Production Example 2: Production of a Solution (R) Containing a Cholesteric Liquid Crystal Composition Capable of Reflecting Red Right-Handed Circularly Polarized Light]

[0242] A solution (R) containing a cholesteric liquid crystal composition capable of reflecting red right-handed circularly polarized light was prepared by the same method as in Preparation Example 1, except that the amount of the chiral agent ("LC756" manufactured by BASF; HSP = 22.8, logP = 3.58) was changed to 6.8 parts. The weighted average HSP and weighted average logP of the polymerizable compound of the cholesteric liquid crystal composition contained in the solution (R) are as follows.

[0243] Weighted average HSP = (24.4 × 100 + 20.9 × 25 + 22.8 × 6.8) ÷ (100 + 25 + 6.8) ≈ 23.65

[0244] Weighted average logP = (6.01 × 100 + 1.75 × 25 + 3.58 × 6.8) ÷ (100 + 25 + 6.8) ≈ 5.08

[0245] [Production Example 3: Production of a Solution (B) Containing a Cholesteric Liquid Crystal Composition Capable of Reflecting Blue Right-Handed Circularly Polarized Light]

[0246] A solution (B) containing a cholesteric liquid crystal composition capable of reflecting blue right-handed circularly polarized light was prepared by the same method as in Preparation Example 1, except that the amount of the chiral agent ("LC756" manufactured by BASF; HSP = 22.8, logP = 3.58) was changed to 9.9 parts. The weighted average HSP and weighted average logP of the polymerizable compound of the cholesteric liquid crystal composition contained in the solution (B) are as follows.

[0247] Weighted average HSP = (24.4 × 100 + 20.9 × 25 + 22.8 × 9.9) ÷ (100 + 25 + 9.9) ≈ 23.63

[0248] Weighted average logP = (6.01 × 100 + 1.75 × 25 + 3.58 × 9.9) ÷ (100 + 25 + 9.9) ≈ 5.04

[0249] [Production Example 4: Production of a Cholesteric Pigment (G) Capable of Reflecting Green Right-Handed Circularly Polarized Light]

[0250] A long polyethylene terephthalate film ("A4100" manufactured by Toyobo Co., Ltd.; thickness 100 μm) was prepared as a substrate film. The substrate film was attached to a delivery portion of a film conveying device, and the following operation was performed while conveying the substrate film in the longitudinal direction.

[0251] The surface of the substrate film was subjected to a rubbing treatment in a longitudinal direction parallel to the conveying direction. Next, the solution (G) containing the cholesteric liquid crystal composition prepared in Preparation Example 1 was applied to the surface of the substrate film subjected to the rubbing treatment using a die coater to form a layer of the cholesteric liquid crystal composition. The layer of the cholesteric liquid crystal composition was subjected to an alignment treatment of heating at 120° C. for 5 minutes. Then, the layer of the cholesteric liquid crystal composition was irradiated with 900 mJ / cm 2 The layer of the cholesteric liquid crystal composition is cured by ultraviolet light. Thus, a multilayer film having a substrate film and a layer of a liquid crystal cured product of the cholesteric liquid crystal composition is obtained. The reflectivity of the layer of the liquid crystal cured product of the multilayer film is measured by the above-mentioned measurement method. The measurement result shows that the layer of the liquid crystal cured product has a selective reflection wavelength range in which the reflectivity of non-polarized light is 40% or more in the range of a central wavelength of 550nm and a reflection band of a central wavelength of ±35nm (i.e., 515nm to 585nm).

[0252] The layer of the liquid crystal solidified material was peeled off from the multilayer film. The layer of the liquid crystal solidified material was crushed and classified to obtain a cholesteric pigment (G) in the form of small flakes. The aspect ratio and thickness of the obtained cholesteric pigment (G) were measured, and the results showed that the aspect ratio was 8.3 and the thickness was 3.2 μm.

[0253] [Production Example 5: Production of a Cholesteric Pigment (R) Capable of Reflecting Red Right-Handed Circularly Polarized Light]

[0254] A cholesteric pigment (R) in the form of a small flake was produced by the same method as in Production Example 4 except that the solution (R) containing the cholesteric liquid crystal composition produced in Production Example 2 was used instead of the solution (G). The cholesteric pigment (R) has a selective reflection wavelength range in which the reflectivity of non-polarized light is 40% or more in a range of a central wavelength of 650 nm and a reflection band of ±35 nm from the central wavelength (i.e., 615 nm to 685 nm). The aspect ratio of the cholesteric pigment (R) is 9.1 and the thickness is 3.5 μm.

[0255] [Production Example 6: Production of a Cholesteric Pigment (B) Capable of Reflecting Blue Right-Handed Circularly Polarized Light]

[0256] A cholesteric pigment (B) in the form of a small flake was produced by the same method as in Production Example 4 except that the solution (B) containing the cholesteric liquid crystal composition produced in Production Example 3 was used instead of the solution (G). The cholesteric pigment (B) had a selective reflection wavelength range in which the reflectivity of non-polarized light was 40% or more in a range of a central wavelength of 450 nm and a reflection band of ±35 nm from the central wavelength (i.e., 415 nm to 485 nm). The cholesteric pigment (B) had an aspect ratio of 10.0 and a thickness of 3.0 μm.

[0257] [Example 1. Production of ink composition capable of reflecting green right-handed circularly polarized light (CLCink_G1)]

[0258] An ink composition (CLCink_G1) was obtained by mixing 100 parts by weight of a colorless and transparent screen printing ink ("SG240_800medium" manufactured by Seiko Ink Co., Ltd.), 10 parts by weight of the cholesteric pigment (G) manufactured in Manufacturing Example 4, 1 part by weight of a liquid crystal compound represented by formula (X1) (molecular weight = 846.3, HSP = 24.4, logP = 6.01) as a stabilizer, and 5 parts by weight of dioxolane (HSP = 21.4) as a diluent.

[0259] The composition of the above-mentioned screen printing ink is as follows.

[0260] (Main ingredient_disclosed ingredient above 1%)

[0261] Acrylic resin: 27 parts by mass

[0262] Olefin resin: 3 parts by mass

[0263] Diacetone alcohol (CAS No. 123-42-2): 37 parts by mass

[0264] Ethylene glycol derivative solvent: 31 parts by mass

[0265] [Example 2. Preparation of ink composition capable of reflecting green right-handed circularly polarized light (CLCink_G2)]

[0266] An ink composition (CLCink_G2) was prepared in the same manner as in Example 1 except that the amount of the liquid crystal compound represented by the formula (X1) (HSP=24.4, logP=6.01) as a stabilizer was changed to 1.5 parts by weight.

[0267] [Example 3. Preparation of ink composition capable of reflecting green right-handed circularly polarized light (CLCink_G3)]

[0268] An ink composition (CLCink_G3) was prepared in the same manner as in Example 1 except that the amount of the liquid crystal compound represented by the formula (X1) (HSP=24.4, logP=6.01) as a stabilizer was changed to 2 parts by weight.

[0269] [Example 4. Preparation of ink composition capable of reflecting right-handed circularly polarized light of green (CLCink_G4)]

[0270] An ink composition (CLCink_G4) was prepared by the same method as in Example 1, except that 0.5 parts by weight of a non-liquid crystal compound represented by formula (X2) (molecular weight = 293.1, HSP = 20.9, logP = 1.75) was used instead of 1 part by weight of a liquid crystal compound represented by formula (X1) as a stabilizer.

[0271] [Example 5. Preparation of ink composition capable of reflecting green right-handed circularly polarized light (CLCink_G5)]

[0272] An ink composition (CLCink_G5) was prepared by the same method as Example 1, except that 1.5 parts by weight of a compound represented by the following formula (X3) ("LC756" manufactured by BASF; molecular weight = 966.3, HSP = 22.8, logP = 3.58) was used instead of 1 part by weight of a liquid crystal compound represented by formula (X1) as a stabilizer.

[0273] [Chemical formula 7]

[0274]

[0275] [Example 6. Preparation of ink composition capable of reflecting green right-handed circularly polarized light (CLCink_G6)]

[0276] An ink composition (CLCink_G6) was prepared by the same method as Example 1, except that 1.5 parts by weight of a compound represented by the following formula (X4) (molecular weight = 816.3, HSP = 19.2, logP = 5.11) was used instead of 1 part by weight of a liquid crystal compound represented by formula (X1) as a stabilizer.

[0277] [Chemical formula 8]

[0278]

[0279] [Example 7. Preparation of ink composition capable of reflecting green right-handed circularly polarized light (CLCink_G7)]

[0280] An ink composition (CLCink_G7) was prepared by the same method as in Example 1 except that the type of diluent was changed to ethanol (HSP=26.5).

[0281] [Example 8. Preparation of ink composition capable of reflecting green right-handed circularly polarized light (CLCink_G8)]

[0282] An ink composition (CLCink_G8) was prepared by the same method as in Example 1 except that the type of diluent was changed to cyclohexane (HSP=16.8).

[0283] [Example 9. Production of ink composition capable of reflecting red right-handed circularly polarized light (CLCink_R1)]

[0284] An ink composition (CLCink_R1) was prepared by the same method as in Example 1 except that 10 parts by weight of the cholesteric pigment (R) prepared in Preparation Example 5 was used instead of 10 parts by weight of the cholesteric pigment (G) and the amount of the stabilizer was changed to 1.5 parts by weight.

[0285] [Example 10. Production of ink composition capable of reflecting blue right-handed circularly polarized light (CLCink_B1)]

[0286] An ink composition (CLCink_B1) was prepared by the same method as in Example 1 except that 10 parts by weight of the cholesteric pigment (B) prepared in Preparation Example 6 was used instead of 10 parts by weight of the cholesteric pigment (G) and the amount of the stabilizer was changed to 1.5 parts by weight.

[0287] [Comparative Example 1. Preparation of an ink composition capable of reflecting green right-handed circularly polarized light (CLCink_G0)]

[0288] An ink composition (CLCink_B0) was prepared by the same method as in Example 1 except that no stabilizer was used.

[0289] [Comparative Example 2. Preparation of an ink composition capable of reflecting red right-handed circularly polarized light (CLCink_R0)]

[0290] An ink composition (CLCink_R0) was prepared by the same method as in Example 1, except that 10 parts by weight of the cholesteric pigment (R) prepared in Preparation Example 5 was used instead of 10 parts by weight of the cholesteric pigment (G) and no stabilizer was used.

[0291] [Comparative Example 3. Preparation of an ink composition capable of reflecting blue right-handed circularly polarized light (CLCink_B0)]

[0292] An ink composition (CLCink_B0) was prepared by the same method as in Example 1, except that 10 parts by weight of the cholesteric pigment (B) prepared in Preparation Example 6 was used instead of 10 parts by weight of the cholesteric pigment (G) and no stabilizer was used.

[0293] [Summary of Ink Composition Compositions]

[0294] The formulations of the ink compositions prepared in the above-mentioned Examples and Comparative Examples are summarized in the following Table 1. In addition, |ΔHSP1|, |ΔlogP1|, and the square root of the sum of squares {|ΔHSP1| in each Example and Comparative Example are shown in Table 1. 2 +|ΔlogP1| 2} 1 / 2 and |ΔHSP2| are summarized in Table 2. In Table 1, the abbreviations have the following meanings.

[0295] DI: Dioxolane

[0296] ET: Ethanol

[0297] CY: Cyclohexane

[0298] [Table 1]

[0299] [Table 1. Composition of ink composition]

[0300]

[0301] [Table 2]

[0302] [Table 2. Parameters of ink composition]

[0303] Ink composition <![CDATA[|ΔHSP1|]]> <![CDATA[|ΔlogP1|]]> Square root of the sum of squares <![CDATA[|ΔHSP2|]]> Example 1 G1 0.75 0.95 1.21 2.25 Example 2 G2 0.75 0.95 1.21 2.25 Example 3 G3 0.75 0.95 1.21 2.25 Example 4 G4 2.75 3.31 4.30 2.25 Example 5 G5 0.85 1.48 1.71 2.25 Example 6 G6 4.45 0.05 4.45 2.25 Example 7 G7 0.75 0.95 1.21 2.85 Example 8 G8 0.75 0.95 1.21 6.85 Comparative Example 1 G0 - - - - Example 9 R1 0.75 0.93 1.19 2.25 Comparative Example 2 R0 - - - - Example 10 B1 0.77 0.97 1.24 2.23 Comparative Example 3 B0 - - - -

[0304] [Durability test]

[0305] The ink compositions prepared in the above-described Examples and Comparative Examples were subjected to the durability test described below.

[0306] As a substrate for printing, a black polyethylene terephthalate substrate (thickness 100 μm) was prepared, and one surface of the substrate was subjected to a corona discharge treatment to improve printability.

[0307] The ink composition was printed on the corona discharge treated surface of the substrate using a 100 mesh screen printing plate to form a rectangular display layer of 5 cm × 30 cm. The display layer was then dried at 60°C for 30 minutes. The reflectance spectrum of the display layer thus obtained was measured to confirm that the display layer had the same reflectance spectrum throughout the rectangle. The center wavelength of the selective reflection wavelength range of the cholesteric pigment contained in the display layer was obtained based on the reflectance spectrum of the display layer before the durability test and was used as the reference value.

[0308] Then, the display layer and the substrate were cut into 5 cm squares to obtain samples. These samples were stored in a high temperature and high humidity tank (temperature 90°C, humidity 80% RH). After 1 day, 3 days, 7 days and 14 days from the start of storage, a portion of the samples was taken out, and the reflection spectrum of the display layer was measured to measure the center wavelength of the selective reflection wavelength range of the cholesteric pigment contained in the display layer.

[0309] The results of each example and comparative example are shown in the following Table 3. In Table 3, the abbreviations have the following meanings.

[0310] Pigment initial value: the center wavelength of the selective reflection wavelength range of the cholesteric pigment before the ink composition is prepared.

[0311] Just after printing (reference value): the central wavelength of the selective reflection wavelength range of the cholesteric pigment before the durability test.

[0312] After 1 day: the center wavelength of the selective reflection wavelength range of the cholesteric pigment after 1 day from the start of storage.

[0313] After 3 days: the center wavelength of the selective reflection wavelength range of the cholesteric pigment after 3 days from the start of storage.

[0314] After 7 days: the center wavelength of the selective reflection wavelength range of the cholesteric pigment after 7 days from the start of storage.

[0315] After 14 days: the center wavelength of the selective reflection wavelength range of the cholesteric pigment after 14 days from the start of storage.

[0316] [Table 3]

[0317] [Table 3. Durability test results]

[0318]

[0319] [discuss]

[0320] Examples 1 to 8 and Comparative Example 1 represent experiments using the same cholesteric pigment. In Comparative Example 1, in which no stabilizer is used, the difference between the center wavelength of the selective reflection wavelength range of the cholesteric pigment contained in the display layer just after printing and the center wavelength of the selective reflection wavelength range of the cholesteric pigment contained in the display layer after storage in a high temperature and high humidity environment is large. In contrast, in Examples 1 to 8, in which a stabilizer is used, the difference between the center wavelength of the selective reflection wavelength range of the cholesteric pigment contained in the display layer just after printing and the center wavelength of the selective reflection wavelength range of the cholesteric pigment contained in the display layer after storage in a high temperature and high humidity environment is small. Therefore, it can be confirmed that by using a stabilizer, the durability of the cholesteric pigment contained in the ink composition is improved, and the change of the selective reflection wavelength range in a high temperature and high humidity environment can be suppressed.

[0321] Among Examples 1 to 8, Examples 1 to 3, 7, and 8 in which the same compound as the liquid crystal compound (polymerizable compound represented by formula (X1)) as the main component monomer of the cholesteric pigment is used as a stabilizer have particularly small changes in the selective reflection wavelength range caused by storage under a high temperature and high humidity environment. Therefore, it can be confirmed that in order to effectively improve the durability of the cholesteric pigment, it is preferred to use the same compound as the polymerizable compound contained in the liquid crystal composition as the raw material of the liquid crystal cured product contained in the cholesteric pigment as a stabilizer, it is preferred to use the same compound as the main component monomer of the liquid crystal composition as a stabilizer, and it is preferred to use a liquid crystal compound as a stabilizer.

[0322] Among Examples 1 to 3 in which the elements other than the amount of the stabilizer are the same, the change in the selective reflection wavelength range due to storage in a high temperature and high humidity environment is particularly small in Example 2. Therefore, it can be confirmed that the amount of the stabilizer is appropriate in order to effectively improve the durability of the cholesteric pigment.

[0323] Among Examples 1, 7, and 8, which have the same elements except for the type of diluent, in Example 7 using a diluent having an HSP of 26 or more (specifically, ethanol) and in Example 8 using a diluent having an HSP of 18 or less (specifically, cyclohexane), the center wavelength of the selective reflection wavelength range of the cholesteric pigment contained in the display layer immediately after printing is close to the center wavelength of the selective reflection wavelength range of the cholesteric pigment before the preparation of the ink composition. Therefore, it is known that from the viewpoint of reducing the change in the selective reflection wavelength range of the cholesteric pigment caused by the preparation of the ink composition, a diluent having an HSP that is large in difference from the weighted average HSP of the polymerizable compound contained in the liquid crystal composition as a raw material of the liquid crystal cured product contained in the cholesteric pigment is preferred.

[0324] In Examples 9 to 10 and Comparative Examples 2 to 3 using cholesteric pigments different from Examples 1 to 8 and Comparative Example 1, the stabilizer can also suppress changes in the selective reflection wavelength range under a high temperature and high humidity environment. Therefore, it can be expected that the above-mentioned effect brought about by the stabilizer can be widely manifested in cholesteric pigments.

Claims

1. An ink composition comprising a cholesteric pigment and a non-volatile organic compound, wherein the cholesteric pigment comprises a cured product of a liquid crystal composition, and the liquid crystal composition comprises a polymerizable compound, The absolute value of the difference between the weighted average of the HSP of the polymerizable compound and the HSP of the organic compound |ΔHSP1| is 3.0 or less, or The absolute value of the difference between the weighted average of the logP of the polymerizable compound and the logP of the organic compound |ΔlogP1| is 1.0 or less, The ink composition comprises an organic solvent, wherein the organic solvent comprises a diluent, An absolute value |ΔHSP2| of a difference between a weighted average of the HSP of the polymerizable compound and the HSP of the diluent is greater than 2.

2. The ink composition according to claim 1, wherein The liquid crystal composition includes the same compound as the organic compound.

3. The ink composition according to claim 1 or 2, wherein The organic compound is a liquid crystal compound.

4. The ink composition according to claim 1 or 2, wherein The square root of the sum of the squares of the absolute value |ΔHSP1| and the absolute value |ΔlogP1| {|ΔHSP1| 2 +|ΔlogP1| 2 } 1 / 2 Below 5.

0.

5. The ink composition according to claim 1 or 2, wherein The square root of the sum of the squares of the absolute value |ΔHSP1| and the absolute value |ΔlogP1| {|ΔHSP1| 2 +|ΔlogP1| 2 } 1 / 2 Below 1.

5.

6. The ink composition according to claim 1 or 2, wherein The polymerizable compound comprises a main component monomer, The amount of the main component monomer contained in the liquid crystal composition is 50% by weight or more relative to 100% by weight of the non-volatile component of the liquid crystal composition, The main component monomer is the same as the organic compound.

7. The ink composition according to claim 1 or 2, wherein The diluent has a HSP of 26 or greater.

8. The ink composition according to claim 1 or 2, wherein: The diluent has a HSP of 18 or less.

9. The ink composition according to claim 1 or 2, wherein: The polymerizable compound includes a compound represented by the following formula X1:

10. The ink composition according to claim 1 or 2, wherein: The cholesteric pigment has a selective reflection wavelength range capable of reflecting circularly polarized light in one rotational direction and transmitting circularly polarized light in a rotational direction opposite to the rotational direction. The wavelength width of the selective reflection wavelength range is greater than 50 nm.

11. The ink composition according to claim 10, wherein The selective reflection wavelength range includes the entire visible light wavelength range.

12. The ink composition according to claim 1 or 2, wherein: The cholesteric pigments are in the form of small flakes.

13. The ink composition according to claim 12, wherein: The thickness of the cholesteric pigment is 20 μm or less.

14. The ink composition according to claim 1 or 2, wherein: The amount of the organic compound is 0.5 parts by weight or more and 10 parts by weight or less relative to 100 parts by weight of the cholesteric pigment.

15. The ink composition according to claim 1 or 2, wherein: When a display layer obtained by applying the ink composition was subjected to a durability test in an environment of temperature 90° C. and humidity 80% RH for 14 days, the change in the central wavelength of the selective reflection wavelength range of the cholesteric pigment was 15 nm or less. 16 . An article having a display layer obtained by applying the ink composition according to claim 1 .

17. A method for producing an article, comprising the step of applying the ink composition according to any one of claims 1 to 15 to form a display layer.

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