Optically anisotropic layer, optical film, polarizing plate, and image display device

An optically anisotropic layer obtained by curing a polymerizable liquid crystal composition including a polymerizable liquid crystal compound having forward wavelength dispersion and a monofunctional compound, in an alignment state of the polymerizable liquid crystal compound,

• wherein the polymerizable liquid crystal compound is a compound represented by Formula (I),
• P1-Sp1-(X1—Ar1)n1—(X2-Cy1)m1-X3—Ar3—X4—(Cy2-X5)m2—(Ar2—X6)n2-Sp2-P2 (I)
• in Formula (I),
• P1 and P2 each independently represent an acryloyloxy group or a methacryloyloxy group,
• wherein P1 includes a first terminal atom and P2 includes a second terminal atom of the polymerizable liquid crystal compound represented by Formula (I),
• wherein the first terminal atom of the polymerizable liquid crystal compound is a starting atom and the second terminal atom of the polymerizable liquid crystal compound represented by Formula (I) is an ending atom utilized to calculate a maximum number of atoms linked together at a shortest distance to form the polymerizable liquid crystal compound represented by Formula (I), wherein the maximum number of atoms linked together at a shortest distance to form the polymerizable liquid crystal compound represented by Formula (I) is counted such that the starting atom and the ending atom are also counted;
• Sp1 and Sp2 each independently represent a single bond, a linear alkylene group having 1 to 14 carbon atoms, a branched alkylene group having 3 to 14 carbon atoms, or a divalent linking group in which one or more of —CH2-s constituting the linear alkylene group or the branched alkylene group are substituted with —O—, —S—, —NH—, —N(Q)-, or —CO—, where Q represents a substituent,
• n1, m1, m2, and n2 each represent an integer from 0 to 4, and a sum of n1, m1, m2, and n2 is 4,
• X1, X2, X3, X4, X5, and X6 each independently represent a single bond;
• or —CO—, —O—, —S—, —C(═S)—, —CR1R2—, —CR3═CR4—, —NR5, or a divalent linking group consisting of a combination of two or more of these groups, where R1 to R5 each independently represent a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 12 carbon atoms, provided that in a case where n1 is an integer of 2 to 4, a plurality of X1s may be the same as or different from each other;
• in a case where m1 is an integer of 2 to 4, a plurality of X2s may be the same as or different from each other;
• in a case where m2 is an integer of 2 to 4, a plurality of X5s may be the same as or different from each other;
• and in a case where n2 is an integer of 2 to 4, a plurality of X6s may be the same as or different from each other,
• Ar1, Ar2 and Ar3 each independently represent an aromatic ring which may have a substituent, provided that in a case where n1 is an integer of 2 to 4, a plurality of Ar1s may be the same as or different from each other;
• and in a case where n2 is an integer of 2 to 4, a plurality of Ar2s may be the same as or different from each other, and
• Cy1 and Cy2 each independently represent an alicyclic ring which may have a substituent, provided that in a case where m1 is an integer of 2 to 4, a plurality of Cy1s may be the same as or different from each other;
• and in a case where m2 is an integer of 2 to 4, a plurality of Cy2s may be the same as or different from each other;
• wherein the monofunctional compound is a compound represented by Formula (II),
• P3-Sp3-(X1—Ar4)n3—(X8-Cy3)m3-(X9—Ar5)n4—X10—Ar6 (II)
• in Formula (II),
• P3 represents an acryloyloxy group or a methacryloyloxy group,
• wherein P3 includes a first terminal atom and Ar6 includes a second terminal atom of the monofunctional compound represented by Formula (II),
• wherein the first terminal atom of the monofunctional compound represented by Formula (II) is a starting atom and the second terminal atom of the monofunctional compound represented by Formula (II) is an ending atom utilized to calculate a maximum number of atoms linked together at a shortest distance to form the monofunctional compound represented by Formula (II), wherein the maximum number of atoms linked together at a shortest distance to form the monofunctional compound represented by Formula (II) is counted such that the first terminal atom and the second terminal atom are also counted;
• Sp3 represents a single bond, a linear alkylene group having 1 to 14 carbon atoms, a branched alkylene group having 3 to 14 carbon atoms, or a divalent linking group in which one or more of —CH2-s constituting the linear alkylene group or the branched alkylene group are substituted with —O—, —S—, —NH—, —N(Q)-, or —CO—, where Q represents a substituent,
• n3, n4, and m3 represent an integer from 0 to 2, and a sum of n3, n4, and m3 is 2,
• X7, X8, X9, and X10 each independently represent a single bond;
• or —CO—, —O—, —S—, —C(═S)—, —CR1R2—, —CR3═CR4—, —NR5—, or a divalent linking group consisting of a combination of two or more of these groups, where R1 to R5 each independently represent a hydrogen atom, a fluorine atom, or an alkyl group having 1 to 12 carbon atoms, provided that in a case where n3 is 2 a plurality of X7s may be the same as or different from each other;
• and in a case where m3 is 2, a plurality of X8s may be the same as or different from each other,
• Ar4 and Ar5 each independently represent an aromatic ring which may have a substituent, provided that in a case where n3 and n4 are 2, a plurality of Ar4s and Ar5s may be the same as or different from each other,
• Ar6 represents a benzene ring which does not have a substituent, and
• Cy3 represents an alicyclic ring which may have a substituent, provided that in a case where m3 is 2, a plurality of Cy3s may be the same as or different from each other;
• wherein the polymerizable liquid crystal compound and the monofunctional compound satisfy a relationship of Expression (1), and satisfy a relationship of Expression (2), and
• wherein the optically anisotropic layer exhibits a smectic phase,
• 0.2<a2/a1<0.55 Expression (1):
• b2=b1×0.5 or b2=(b1+1)×0.5 Expression (2):
• wherein in Expression (1), a1 is the maximum number of atoms linked together between the starting atom and the ending atom at the shortest distance to form the polymerizable liquid crystal compound represented by Formula (I), counted such that the starting atom and the ending atom are also counted;
• and
• a2 is the maximum number of atoms linked together between the starting atom and the ending atom at the shortest distance to form the monofunctional compound represented by Formula (II), counted such that the starting atom and the ending atom are also counted, and
• wherein in Expression (2), b1 is the number of substituted and unsubstituted aromatic rings present in (X1—Ar1)n1, Ar3, and (Ar2—X6)n2, and the number of substituted and unsubstituted alicyclic rings present in (X2-Cy1)m1, and (Cy2-X5)m2 of Formula (I);
• and
• b2 is the number of substituted and unsubstituted aromatic rings present in (X7—Ar4)n3, (X9—Ar5)n4, and Ar6, and the number of substituted and unsubstituted alicyclic rings present in (X8-Cy3)m3 of Formula (II).