JP2005106946A - Liquid crystal composition and method for producing polymeric liquid crystal using the liquid crystal composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal composition excellent in heat resistance and a method for producing a polymeric liquid crystal. <P>SOLUTION: The liquid crystal composition contains two or more compounds selected from a compound (A) having a methogen group and a functional group which photopolymerizes, a compound (B) having a methogen group, a crosslinkable functional group (y) and a functional group which photopolymerizes, a compound (C) having a crosslinkable functional group (y) and a functional group which photopolymerizes, a compound (D) having a second crosslinkable functional group (z) and a functional group which photopolymerizes, a compound (E) having a methogen group, a second crosslinkable functional group (z) and a functional group which photopolymerizes, and a compound (F) having two or more second crosslinkable functional groups (z) and not causing photopolymerization, wherein at least the methogen group, the crosslinkable functional group (y) and the second crosslinkable functional group (z) are included. The crosslinkable functional groups (y) and (z) do not react by photopolymerization but react by heating and bond together. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid crystal composition used for an optical element such as a retardation plate and a polarization hologram, and a method for producing a polymer liquid crystal film using the liquid crystal composition.

  A polymerizable liquid crystal compound in which a polymerizable functional group is added to a liquid crystal molecule has both a property as a polymerizable monomer and a property as a liquid crystal. Therefore, by polymerizing the polymerizable liquid crystal compound in an aligned state, a polymer having a fixed molecular alignment, that is, a polymer liquid crystal can be obtained. The polymer liquid crystal thus obtained exhibits optical anisotropy derived from the refractive index anisotropy of the liquid crystalline skeleton, that is, birefringence, and can impart special characteristics by controlling the liquid crystal alignment state. And optical elements such as polarization holograms.

  However, when a polymer liquid crystal obtained by polymerizing the above polymerizable liquid crystal compound is applied to an optical element such as a retardation plate or a polarization hologram element, the heat resistance of the birefringence of the polymer liquid crystal becomes a problem.

In general, the birefringence of a liquid crystal compound greatly depends on temperature, decreases with increasing temperature, and disappears at a liquid crystal phase-isotropic phase transition temperature, so-called clearing point (T _c ). Therefore, in order to maintain the optical performance of the optical element within a predetermined use temperature range, a polymer liquid crystal having _Tc on the higher temperature side than the upper limit of the use temperature range of the optical element is required.

As a method for obtaining such a polymer liquid crystal exhibiting a high _Tc , for example, JP-A-2001-89529 discloses a method using a liquid crystalline compound exhibiting a high _Tc as a polymerizable liquid crystal monomer.

Japanese Patent Application Laid-Open No. 2001-220583 discloses that a polymer liquid crystal composition containing a photocrosslinkable polymerizable monomer is polymerized and cured in advance to crosslink the polymer main chain to increase the polymer liquid crystal. _Tc conversion is disclosed.

Furthermore, Japanese Patent Application Laid-Open No. 2000-144133 discloses that a polymer liquid crystal is synthesized in a solution in advance, an acrylate group is introduced into the side chain, and the acrylate moiety introduced into the side chain of the polymer liquid crystal is converted to light or heat. The method of making it react and crosslinking is disclosed.
JP 2001-89529 A Japanese Patent Laid-Open No. 2001-220583 JP 2000-144133 A

Among the above conventional techniques, as disclosed in JP-A-2001-89529, in a method using a liquid crystal compound exhibiting a high _Tc as a polymerizable liquid crystal monomer, the viscosity of the polymerizable liquid crystal monomer is high, so When encapsulated and used, injection into the cell is difficult and workability is poor.

  In addition, a method of polymerizing and curing a polymerizable liquid crystal composition containing a photocrosslinkable polymerizable monomer in advance as in JP-A-2001-220583 is particularly effective for improving heat resistance on the high temperature side. However, since the compatibility between the photocrosslinkable polymerizable monomer and the polymerizable liquid crystal monomer is generally poor and the chemical structure and content thereof are limited, the spread of the liquid crystal temperature range is small, or the liquid crystal properties are difficult to develop. There is.

  In the method of JP-A No. 2000-144133, the process is complicated because an acrylate group must be introduced into the side chain after the polymer liquid crystal has been synthesized in solution in advance. In order to produce an optical element from the above polymer liquid crystal, a polymer liquid crystal solution is first prepared, and then the polymer liquid crystal solution is applied on a substrate provided with an alignment film, and then heated to a glass transition temperature or higher. Aligning the polymer liquid crystal and then cooling it to below the glass transition temperature freezes the alignment, and finally requires many steps to crosslink the acrylate group by light irradiation, which complicates the work. There is a problem of becoming.

  Accordingly, an object of the present invention is to provide a liquid crystal composition capable of improving the heat resistance of a polymer liquid crystal by a simple process and a method for producing a polymer liquid crystal film using the liquid crystal composition.

In order to achieve the above object, the liquid crystal composition of the present invention is a polymerizable liquid crystal composition containing two or more compounds selected from the following compounds (A) to (F), and the composition is a mesogenic group. It is characterized by comprising a combination including (x), a crosslinkable functional group (y), and a second crosslinkable functional group (z).
(However, the following crosslinkable functional group (y) and the following second crosslinkable functional group (z) do not substantially react under light irradiation in photopolymerization and both react by heating. (Combined combination)
(1): Compound (A) having a mesogenic group (x) and a photopolymerizable functional group.
(2): Compound (B) having a mesogenic group (x), a crosslinkable functional group (y), and a photopolymerizable functional group.
(3): Compound (C) having a crosslinkable functional group (y) and a photopolymerizable functional group.
(4): Compound (D) having a second crosslinkable functional group (z) and a photopolymerizable functional group.
(5): Compound (E) having a mesogenic group (x), a second crosslinkable functional group (z), and a photopolymerizable functional group.
(6): A compound (F) that does not photopolymerize and has two or more second crosslinkable functional groups (z).

In the liquid crystal composition of the present invention, the two crosslinkable functional groups are not substantially reacted by light, but have the property of reacting by heat, so that the polymers after photopolymerization are heated with each other. Causes cross-linking. Thereby, the polymer liquid crystal excellent in heat resistance can be obtained without impairing the orientation before and after photopolymerization. Moreover, since the compatibility of the compounds (A) to (F) is good, the degree of freedom in selecting each compound is high, and the content of the compound having a crosslinkable functional group can be increased. Thereby, the spread of the liquid crystal temperature range can be increased, and a polymer liquid crystal having good alignment characteristics can be obtained. In addition, since an increase in the viscosity of the liquid crystal composition can be suppressed while exhibiting a high _Tc , it is easy to fill the cell with the composition.

  In the liquid crystal composition of the present invention, the crosslinkable functional group (y) and the second crosslinkable functional group (z) (hereinafter also simply referred to as crosslinkable functional group (z)) are present in substantially equivalent amounts. A combination is preferred. Crosslinkable functional groups are often unstable and are preferably not present in the final crosslinked polymer liquid crystal. By making the two types of crosslinkable functional groups equivalent, the remaining amount of the crosslinkable functional groups after crosslinking can be reduced.

  Moreover, it is preferable that the combination of both crosslinkable functional groups is a combination bonded by an addition reaction. If the functional group is bonded by an addition reaction, no by-product is generated as in the case of the condensation reaction, and the risk of deterioration of the properties of the polymer liquid crystal due to the crosslinking reaction is reduced.

  Examples of the addition reaction include a combination of a functional group having an active hydrogen atom that can be bonded to an isocyanate group (such as a hydroxyl group or an amino group) and an isocyanate group. The combination of both crosslinkable functional groups in the present invention is preferably a combination of an active hydrogen atom-containing functional group capable of bonding with an isocyanate group and an isocyanate group. The isocyanate group is a highly active functional group and easily reacts with the active hydrogen atom-containing functional group, so that crosslinking in the present invention easily occurs. That is, in the case of this combination, since the crosslinking is easy, the adverse effect on the polymer liquid crystal in the crosslinking reaction can be reduced.

  Crosslinking can also be performed by linking polymers having one crosslinkable functional group with a low molecular compound having two or more other crosslinkable functional groups. This low molecular weight compound is the compound (F). In the liquid crystal composition of the present invention, the compound (F) is not photopolymerizable and does not substantially react at the stage of photopolymerization of other compounds. The photopolymerization reaction is usually performed under reaction conditions at a relatively low temperature. In this case, the crosslinkable functional group (z) in the compound (F) is different from the crosslinkable functional group (y) in other photopolymerizable compounds. It is thought that it does not react substantially. These two types of crosslinkable functional groups undergo a reaction under heating conditions that are higher than the reaction conditions for the photopolymerization reaction, thereby forming crosslinks.

  The combination of each compound in the liquid crystal composition of the present invention is composed of at least one compound (A), at least one compound selected from compound (B) and compound (C), and compound (D) and compound (F). It is preferable to consist of a combination of at least one selected. The compound (A) does not have a crosslinkable functional group, but is preferably used as a main component of the photopolymerizable liquid crystal of the liquid crystal composition. The compound having a crosslinkable functional group may not have a mesogenic group (x) (compound (C), compound (D)), and may not be photopolymerizable (compound (F)). The compound is present in a small amount in the composition as compared with the compound having liquid crystallinity, and is present in a small amount in the composition as compared with the photopolymerizable compound.

  The present invention also provides a method for producing a polymer liquid crystal, wherein the above liquid crystal composition is photopolymerized in a state where the liquid crystal composition is aligned, and then the resulting polymer is heated to perform a crosslinking reaction. is there.

  By this production method of the present invention, an aligned and crosslinked polymer liquid crystal can be easily obtained. According to this method, a polymer liquid crystal with good orientation can be obtained by photopolymerizing the aligned liquid crystal composition, and then thermal crosslinking is carried out in the same manner as the conventional polymer liquid crystal production method. As a result, it is possible to obtain a crosslinked polymer liquid crystal having good heat resistance by crosslinking without disturbing the orientation of the polymer liquid crystal.

  The present invention further includes an alignment step of filling the liquid crystal composition in a cell and aligning the liquid crystal composition, a photopolymerization step of photopolymerizing the aligned liquid crystal composition by light irradiation, and the photopolymerization. A method for producing a polymer liquid crystal, comprising: a crosslinking step in which a polymer produced by the above is heated to perform a crosslinking reaction.

  According to the production method of the present invention, since the alignment, photopolymerization, and thermal crosslinking of the liquid crystal composition can be sequentially performed in the cell, a polymer liquid crystal can be obtained with a simple work process and high productivity.

  According to the present invention, a polymer liquid crystal having excellent heat resistance can be obtained by merely photopolymerizing and heat-treating a liquid crystal composition without passing through a number of complicated steps and without impairing liquid crystallinity before and after polymerization. be able to.

  In the present invention, the “functional group capable of photopolymerization” is a functional group having an unsaturated double bond that can be polymerized by light such as ultraviolet rays, such as a vinyl group, an allyl group, an acryloyloxy group, a methacryloyloxy group, 2 -Haloacryloyloxy group, vinyloxy group, allyloxy group, and the like, and acryloyloxy group and methacryloyloxy group are particularly preferable. Hereinafter, the photopolymerizable functional group is also referred to as a photopolymerizable group.

  In the present invention, the “mesogen group (x)” is a rigid rod-like divalent organic group also called a mesogen skeleton, and a 6-membered ring having a bond at the para position is connected by a linking group (including a single bond). And a divalent group having 2 to 5 6-membered rings. A mesogenic group is an essential group for a molecule having liquid crystallinity, but not all molecules having a mesogenic group have liquid crystallinity. If two bonds of the 6-membered ring in the mesogen group can be located in the trans position and the cis position, the two bonds are located in the trans position. Examples of the divalent group consisting of a 6-membered ring include 1,4-phenylene group, trans-1,4-cyclohexylene group, 1,4-cyclohexenylene group, pyridine-2,5-diyl group, pyrimidine- 2,5-diyl group, pyrazine-2,5-diyl group, pyridazine-3,6-diyl group and trans-1,3-dioxane-2,5-diyl group are preferred. A hydrogen atom bonded to a carbon atom at a position other than the bond of these 6-membered rings may be substituted with a methyl group, a methoxy group, a trifluoromethyl group, a cyano group, a fluorine atom, a chlorine atom, or the like. A more preferred divalent group consisting of a 6-membered ring is an unsubstituted 1,4-phenylene group or a trans-1,4-cyclohexylene group.

As the linking group for linking the 6-membered ring, a single bond, —CH ₂ CH ₂ —, —CH═CH—, —CF═CF—, —C≡C—, —COO—, —OCO—, —CF ₂ O—, —OCF ₂ —, —CH ₂ O—, —OCH ₂ —, —CONH—, —NHCO—, —CH═N—, —N═CH—, —N═N—, —N═N (O)-, -N (O) = N- and the like are preferable. The linking group other than a single bond is preferably 0 to 2 in one molecule, and particularly preferably 0 or 1.

  In the present invention, the “crosslinkable functional group (y)” and the “second crosslinkable functional group (z)” do not substantially react under light irradiation in photopolymerization and both react by heating. Refers to a combination of functional groups.

  Specifically, as one of the crosslinkable functional groups, a functional group having high activity that can easily react under a relatively low temperature condition such as an isocyanate group or an epoxy group is preferable. In particular, one functional group is preferably an isocyanate group. The other functional group is a functional group that can be bonded by reacting with these functional groups, and a combination that bonds by a reaction (addition reaction) in which a side reaction product is not generated is preferable. When one functional group is an isocyanate group, the other functional group includes an active hydrogen atom-containing functional group such as a hydroxyl group, an amino group, or a carboxyl group, but a carboxyl group is preferable because carbon dioxide is by-produced. Absent. The other functional group is preferably a hydroxyl group and an amino group, and particularly preferably a hydroxyl group. When one functional group is an epoxy group, the other functional group includes an active hydrogen atom-containing functional group such as a hydroxyl group, an amino group, or a carboxyl group, and a hydroxyl group or an amino group is preferable.

  Hereinafter, the present invention will be described mainly using the case where the crosslinkable functional group (y) in the present invention is a hydroxyl group and the crosslinkable functional group (z) is an isocyanate group. This combination is arbitrary, and it goes without saying that the crosslinkable functional group (y) may be an isocyanate group and the crosslinkable functional group (z) may be a hydroxyl group. In addition, the present invention will be described mainly using acryloyloxy group and methacryloyloxy group as photopolymerizable groups.

In the present invention, the compound (A) having a mesogenic group (x) and a photopolymerizable functional group is preferably a compound represented by the following formula (I).

In the above formula (I), R ¹ is a hydrogen atom or a methyl group, and is preferably a hydrogen atom.

E ¹ , E ² , E ³ and E ⁴ each independently represent a divalent group consisting of a 6-membered ring in the mesogenic group (x). Z ¹ , Z ² and Z ³ each independently represent a linking group in the mesogenic group (x). p and q each independently represent 0 or 1. The formula in _{^{(I), - (E 1}} -Z 1) p -E 2 -Z 2 -E 3 - (Z 3 -E 4) q - is an example of a mesogenic group in the present invention (x).

E ¹ , E ² , E ³ , and E ⁴ each independently represent a 1,4-phenylene group (hereinafter represented by Ph in the chemical formula) and a trans-1,4-cyclohexylene group (hereinafter represented by Cy in the chemical formula). It is preferably a divalent group selected from Z ¹ , Z ² and Z ³ are each independently a linking group selected from a single bond, —COO—, —OCO—, —C≡C—, —CH═CH— and —CH ₂ CH ₂ —. It is particularly preferable that Z ² is a group selected from these linking groups and that both Z ¹ and Z ³ are single bonds. It is preferable that p and q are both 0 or one is 1 and the other is 0.

In the above formula (I), Q represents a spacer that connects the mesogenic group (x) and the photopolymerizable functional group. The spacer is a divalent group having a lower volume than the mesogenic group (x) and serves as a buffer so as not to inhibit the orientation of the mesogenic group (x) even after polymerization. There may be no spacer, that is, a single bond. The spacer other than a single bond is preferably a divalent organic group such as — (CH ₂ ) _m — or — (R ³ —O—) _n —. R ³ represents an alkylene group having 2 to 12 carbon atoms, m represents an integer of 1 to 12, and n represents an integer of 1 to 8. If the length of the spacer is too short, the role of the buffer cannot be sufficiently fulfilled, and if the length of the spacer is too long, the temperature dependence of the refractive index anisotropy in the polymer liquid crystal becomes large. Accordingly, R ³ is preferably a polymethylene group having 2 to 10 carbon atoms when n is 1, and is preferably a dimethylene group, a tetramethylene group or a propylene group when n is 2 or more. m is preferably 2 to 10, and n is preferably 1 to 4.

The compound (A) in the present invention is a compound having a mesogenic group (x) and a photopolymerizable functional group, and does not have a crosslinkable functional group. As the compound (A), a compound represented by the formula (I) in which R ² is a group having no crosslinkable functional group is preferable. The number of photopolymerizable functional groups is preferably one. Examples of R ² in this compound (A) include a hydrogen atom, a halogen atom, a cyano group, and an organic group having no crosslinkable functional group. The organic group having no crosslinkable functional group refers to a monovalent organic group having no photopolymerizable group other than the crosslinkable organic group (y) and the second crosslinkable organic group (z). Examples of organic groups having no crosslinkable functional group include alkyl groups, alkenyl groups, alkynyl groups, haloalkyl groups, alkoxy groups, alkoxycarbonyl groups, alkoxycarbonyloxy groups, acyl groups, acyloxy groups, haloacyl groups, haloacyloxy groups, and the like. An organic group having 12 or less carbon atoms is preferred. The organic group may have a short branch, but is preferably a linear organic group. As the halogen atom, a fluorine atom and a chlorine atom are preferable, and a fluorine atom is particularly preferable. R ² is particularly preferably a cyano group, an alkyl group having 6 or less carbon atoms, an alkoxy group having 6 or less carbon atoms, an alkoxycarbonyl group having 6 or less carbon atoms, and an alkoxycarbonyloxy group having 6 or less carbon atoms.

Specific examples of the compound (A) are shown below, but the compound (A) in the present invention is not limited thereto. However, a represents an integer of 2 to 10, and R ¹⁰ represents an alkyl group having 6 or less carbon atoms.

In some cases, the compound (A) in the present invention may be a compound having a mesogenic group (x) and two photopolymerizable functional groups. In this case, R ² is preferably a group represented by —Y—OCOCHR ¹ ═CH ₂ (Y and R ¹ are the same as above). The compound (A) having two photopolymerizable groups needs to be used in combination with the compound (A) having one photopolymerizable group, and alone is not sufficiently compatible with other components of the composition. . Although it is preferable that this compound (A) is not substantially used, when it is used in combination with the compound (A) having one photopolymerizable group, the compound (A) having two photopolymerizable groups with respect to the total of both. Is preferably 10 mol% or less. The compound (A) is preferably a compound represented by the formula (I) having one mesogenic group and one photopolymerizable group.

The compound (B) in the present invention is a compound having a mesogenic group (x), a crosslinkable functional group (y) and a photopolymerizable functional group, and the compound (E) is a mesogenic group (x) and a crosslinkable functional group ( z) and a compound having a photopolymerizable functional group. As these compounds, a compound represented by the formula (I) in which R ² is a crosslinkable functional group or a group having a crosslinkable functional group is preferable. These compounds are also preferably compounds having one photopolymerizable group, one mesogenic group (x) and one crosslinkable functional group.

  As described above, the crosslinkable functional group includes an isocyanate group, an epoxy group, a hydroxyl group, an amino group, and the group having the crosslinkable functional group includes an organic group having these groups. The number of carbon atoms in the organic group portion is preferably 12 or less, particularly preferably 6 or less. Moreover, it is preferable that an organic group part is linear. The isocyanate group-containing organic group is preferably an alkyl group having 6 or less carbon atoms, and the hydroxyl group-containing organic group is preferably a hydroxyalkyl group having 6 or less carbon atoms, a hydroxyalkoxy group, a hydroxyacyl group, or the like. The epoxy group-containing organic group is preferably an epoxy alkyl group having 8 or less carbon atoms (such as a glycidyl group), a glycidyloxyalkyl group, a glycidyloxyalkoxy group, a glycidyloxycarbonyl group, a glycidyloxycarbonylalkyl group, and the like. A glycidyloxyalkyl group having a number of 6 or less is preferred. The amino group-containing organic group is preferably an aminoalkyl group or aminoalkoxy group having 6 or less carbon atoms.

As the compound (B), a compound represented by the formula (I) in which R ² is a hydroxyl group, a hydroxyalkyl group having 6 or less carbon atoms, or a hydroxyalkoxy group having 6 or less carbon atoms is preferable. As the compound (E), a compound represented by the formula (I) in which R ² is an isocyanate group or an isocyanate alkyl group having 4 or less carbon atoms is preferable.

Although the specific example of a compound (B) and a compound (E) is shown below, the compound (B) in this invention and a compound (E) are not limited to these. However, a represents an integer of 2 to 10, and R ¹¹ represents an alkylene group having 2 to 6 carbon atoms. Examples of the compound (B) include the following specific examples.

  Specific examples of the compound (E) include the following.

  The compound (A), the compound (B) and the compound (E) which are compounds having a mesogenic group (x) do not necessarily have to have liquid crystallinity, but the present invention includes at least one of them. The liquid crystal composition must have liquid crystallinity. Therefore, any of these compounds in the liquid crystal composition of the present invention needs to have liquid crystallinity, and the compound (A) usually has liquid crystallinity. Although the compound (B) and the compound (E) do not necessarily have liquid crystallinity, they need to have liquid crystallinity when they are not used in combination with the compound (A). Moreover, when 2 or more types of compounds (A) are used together, some of the compounds (A) may not have liquid crystallinity. Among these compounds, compounds having no liquid crystallinity have a mesogenic group (x), and therefore have an affinity for a mesogenic group (x) -containing compound having liquid crystallinity, and are effective in improving the characteristics of the liquid crystal composition. is there. In the present invention, the compound (B) or the compound (E) having no liquid crystallinity has an affinity for a compound having liquid crystallinity and has a crosslinkable functional group, so that the liquid crystal of the liquid crystal composition of the present invention. It is useful as a component for causing a crosslinkable functional group to be present in the composition without impairing the properties as described above. Of course, it is preferable that all of these compounds (A), (B), and (E) are compounds having liquid crystallinity.

  The compound (C) in the present invention is a compound having a crosslinkable functional group (y) and a photopolymerizable functional group, and the compound (D) has a crosslinkable functional group (z) and a photopolymerizable functional group. A compound. These compounds are compounds having no mesogenic group (x), but may be ring-containing compounds containing a 6-membered ring as described above. These compounds are preferably compounds having one crosslinkable functional group and one photopolymerizable group. As these compounds, compounds represented by the following formula (II) are preferable.

In formula (II), R ¹ represents a hydrogen atom or a methyl group, K represents a single bond or a divalent organic group, and R ⁴ represents a crosslinkable functional group or a group having a crosslinkable functional group. . The group having a crosslinkable functional group is preferably an organic group as described above when R ² is a group having a crosslinkable functional group. K is preferably a divalent organic group such as — (CH ₂ ) _m — or — (R ⁵ —O—) _n —R ⁶ —. ^Wherein, R 5, ^{R 6} are each independently an alkylene group having 1 to 12 carbon atoms, m is an integer of 1 to 12, n is an integer of 1-8, shown. When n is 1, R ⁵ and R ⁶ are preferably each independently a polymethylene group having 2 to 10 carbon atoms. When n is 2 or more, R ⁵ is preferably a dimethylene group, a tetramethylene group and a propylene group, and R ⁶ is preferably a polymethylene group having 2 to 10 carbon atoms. m is preferably 2 to 10, and n is preferably 1 to 4. R ^{4, which} is a crosslinkable functional group or a group having a crosslinkable functional group, is preferably those groups when R ² is a crosslinkable functional group or a group having a crosslinkable functional group. —K—R ⁴ is preferably a crosslinkable functional group-containing organic group having 2 to 12 carbon atoms excluding the crosslinkable functional group.

  Specific examples of the compound (C) and the compound (D) are shown below, but the compound (C) and the compound (D) in the present invention are not limited to these. However, a represents an integer of 2 to 10, and b represents an integer of 2 to 4. Specific examples of the compound (C) include the following.

化合物（Ｄ）としては以下の具体例が挙げられる。

Specific examples of the compound (D) include the following.

  The compound (F) in the present invention is a non-photopolymerized compound having two or more crosslinkable functional groups (z). The compound (F) is a compound that crosslinks by bonding molecules of a polymer liquid crystal having a crosslinkable functional group (y) formed by photopolymerization. If the number of crosslinkable functional groups (z) in the compound (F) is 2 or more, crosslinking is possible, but if the number is too large, the orientation of the polymer liquid crystal may be disturbed, and crosslinking in one molecule The number of the functional functional group (z) is preferably 2 to 3, particularly preferably 2. The compound (F) may be a compound having a ring such as the 6-membered ring, but is usually a compound having no mesogenic group (x). As the compound (F), a compound having two crosslinkable functional groups (z) represented by the following formula (III) is preferable.

  In the above formula (III), Z represents a crosslinkable functional group (z), and W represents a divalent organic group. Examples of W include an alkylene group having 2 to 12 carbon atoms and a hydrocarbon group containing 6 to 16 carbon atoms having 1 to 2 cycloalkylene groups, particularly a polymethylene group having 4 to 8 carbon atoms. Is preferred. When Z is an isocyanate group, specific compounds include, for example, tetramethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, lysine diisocyanate, transcyclohexane-1,4-diisocyanate, isophorone diisocyanate, bicyclohexylmethane-4, 4'-diisocyanate and the like. When Z is an isocyanate group, particularly preferred compounds (F) are tetramethylene diisocyanate and hexamethylene diisocyanate.

  In the liquid crystal composition of the present invention, two or more compounds (A) to (F) can be used. In particular, the compound (A) is preferably used in combination of two or more in order to variously adjust the physical properties of the liquid crystal composition according to the purpose.

  The liquid crystal composition of the present invention comprises a combination containing a mesogenic group (x), a crosslinkable functional group (y), and a crosslinkable functional group (z). Since the compound having a crosslinkable functional group (y) and the compound having a crosslinkable functional group (z) are different compounds, the liquid crystal composition of the present invention is selected from compounds (B) to (F). Each having at least one group. Moreover, since the liquid crystal composition of the present invention has liquid crystallinity, it contains at least one compound having a mesogenic group (x) selected from the compound (A), the compound (B), and the compound (E). Moreover, the liquid crystal composition of the present invention has photopolymerizability because it contains at least one compound having a photopolymerizable group selected from the compounds (A) to (E).

  Specific combinations of the compounds in the liquid crystal composition of the present invention include compound (B) / compound (D), compound (B) / compound (E), compound (B) / compound (F), and compound (C). / Compound (E), Compound (A) / Compound (C) / Compound (D), Compound (A) / Compound (C) / Compound (F), Compound (A) / Compound (B) / Compound (D) Compound (A) / Compound (B) / Compound (E), Compound (A) / Compound (B) / Compound (F), Compound (A) / Compound (C) / Compound (E), Compound (A) / Compound (B) / compound (C) / compound (F), compound (A) / compound (B) / compound (C) / compound (D) and the like.

  The liquid crystal composition of the present invention includes at least one compound (A), at least one compound selected from the compound (B) and the compound (C), and at least one compound selected from the compound (D) and the compound (F). It is preferable to consist of the combination of these. Particularly preferred combinations as specific combinations are the combination of compound (A) / compound (C) / compound (F) and the combination of compound (A) / compound (B) / compound (D). In these combinations, the compound (A) is preferably contained in two or more types as described above. The compound (A) is preferably a combination of 2 to 5 types having different liquid crystal properties.

  The ratio of the crosslinkable functional group (y) and the crosslinkable functional group (z) in each compound in the liquid crystal composition of the present invention is not particularly limited as long as a desired degree of crosslinking is obtained. However, the crosslinkable functional group (y) and the crosslinkable functional group (z) having a higher activity among the crosslinkable functional groups (y) after the crosslinking reaction do not substantially remain after the crosslinking. It is preferable for reasons such as high properties and low alteration. The more active crosslinkable functional group is an isocyanate group or an epoxy group. For example, when the crosslinkable functional group (z) is an isocyanate group, the number of isocyanate groups in the liquid crystal composition of the present invention is preferably equal to or less than the number of crosslinkable functional groups (y). In this case, the number of crosslinks produced is the number of isocyanate groups. Furthermore, it is preferable that the crosslinkable functional group (y) remaining after the crosslinking is also small. Therefore, the ratio of the number of the crosslinkable functional group (y) and the crosslinkable functional group (z) in the liquid crystal composition is expressed by 2 / (crosslinkable functional group (y) / crosslinkable functional group (z)). It is preferably 1 to 1/1, and more preferably 1/1 (that is, both are equivalent).

Further, as described later, in the crosslinked polymer liquid crystal obtained by photopolymerizing the liquid crystal composition of the present invention and then thermally crosslinking, the length L ₁ of the aligned side chain and the length L ₂ between the crosslinking points are 1 .5L ₁ > L ₂ > L ₁ (especially 1.2L ₁ > L ₂ > L ₁ ), it is preferable to have the relationship of compounds (A) to It is preferred that each of the compounds (F) is selected.

The length L ₁ of the aligned side chain in the crosslinked polymer liquid crystal refers to the molecular length of a monovalent group containing a mesogenic group (x) bonded to a carbon atom of the main chain. For example, it is the molecular length of the side chain part containing the mesogenic group (x) in the polymerization unit of the compound (A), the compound (B) that has not undergone crosslinking reaction, and the polymerization unit of the compound (E). This side chain portion corresponds to a monovalent group including a mesogenic group (x) bonded to one carbon atom of a photopolymerizable double bond in the compound (A), the compound (B), and the compound (E). . For example, in the following compounds, which is an example of a compound (A) (A-1) , it refers to the length of the carbon atoms C ² to the nitrogen atom of the cyano group.

The length L ₂ between the crosslinking points in the crosslinked polymer liquid crystal is the molecular length of the crosslinked portion where the crosslinking functional group (y) and the crosslinking functional group (z) are bonded, that is, from the carbon atom of one main chain to the other main chain. It refers to the molecular length of the bridging moiety up to the carbon atom of the chain. An organic group having a crosslinkable functional group (y) bonded to a carbon atom of one main chain (including the case of only the crosslinkable functional group (y)) and a crosslinkable functional group bonded to a carbon atom of the other main chain When the organic group having (z) (including the case of only the crosslinkable functional group (z)) is linked, the total length of these organic groups (including the bonding portion between the crosslinkable functional groups) is obtained. An organic group having a crosslinkable functional group (y) bonded to a carbon atom of one main chain (including the case of only the crosslinkable functional group (y)) and the same crosslinkable functional group bonded to a carbon atom of the other main chain When an organic group having a group (y) (including the case of only a crosslinkable functional group (y)) is linked via a non-photopolymerizable compound (F) having two crosslinkable functional groups (z) The total length of the three members (including the bonding portion between the crosslinkable functional groups). For example, the cross-linked portion in the following cross-linked product (v), which is an example of the latter three-membered bond, refers to the molecular length from carbon atom C ^{3 in} one main chain to carbon atom C ^{4 in the} other main chain.

The length L ₁ of the oriented side chain and the length L ₂ between the crosslinking points mean the molecular length based on the carbon atom of the main chain as described above, and the atom with the longest distance in the optimized molecular structure It is defined by the distance between atoms. The L ₁ and L ₂ can be determined from the molecular structure using the software “Chem 3D” (Cambridge Scientific Computing Inc.). Specifically, for example, L ₁ in the compound (A-1) is 17.7%, and L ₂ in the crosslinked product (v) is 28.5%.

The relationship between L ₁ and L ₂ in the crosslinked polymer liquid crystal obtained by polymerizing and crosslinking the liquid crystal composition of the present invention is an important requirement for maintaining the order of the polymer liquid crystal. For example, when L ₂ is shorter than L ₁ , the liquid crystal alignment is disturbed by the fact that the main chain interval is shorter than the molecular length of the side chain aligned by crosslinking. That is, an uncrosslinked polymer liquid crystal is produced by the polymerization of the oriented liquid crystal composition, but the orientation is lowered due to the occurrence of crosslinking that is shorter than the length of the aligned liquid crystal portion by the subsequent crosslinking. Meanwhile, L ₂ may be 1.5 or more L _1, it is not restricted mobility of the liquid crystal portion oriented by crosslinking, crosslinking is reduced the effect of improving heat resistance of the polymer liquid crystal of interest. Therefore, if 1.5L ₁ > L ₂ > L ₁ , the order of the cross-linked polymer liquid crystal is similar to that of the uncross-linked polymer liquid crystal, and the optical properties are maintained. The heat resistance as a polymer liquid crystal is improved.

  In the liquid crystal composition of the present invention, the proportion of the compound having a mesogenic group (x) with respect to the total number of moles of the compounds (A) to (F) present in the liquid crystal composition is suitably 10 mol% or more. 30 mol% or more is preferable. When the proportion of the compound having a mesogenic group (x) is small, the liquid crystallinity of the composition is not sufficient, and it is difficult to obtain a composition having liquid crystallinity. A more preferable ratio of the compound having a mesogenic group (x) is 55 mol% or more.

  Further, in the liquid crystal composition of the present invention, the crosslinkable functional group having a lower activity with respect to the total number of moles of the compounds (A) to (F) present in the liquid crystal composition (assumed to be a crosslinkable functional group (y)). ) Is suitably 1 to 90 mol%, preferably 5 to 70 mol%. When the compound having a crosslinkable functional group (y) does not contain a mesogenic group (x), 1 to 50 mol% is appropriate, and 5 to 30 mol% is preferable. Furthermore, when using a crosslinkable functional group-containing compound so that an unreacted crosslinkable functional group does not substantially remain after crosslinking, the proportion of the compound having a crosslinkable functional group (y) is 2 to 35 mol%. It is preferable that it is 5 to 25 mol%. The crosslinkable functional group in the case where an unreacted crosslinkable functional group may substantially remain after crosslinking is a crosslinkable functional group that is less active than the other crosslinkable functional group, such as a hydroxyl group or amino group. It is a group.

  The compound having a crosslinkable functional group having higher activity (assuming it is assumed to be a crosslinkable functional group (z)) is preferably equivalent to or less than the crosslinkable functional group (y). For example, the liquid crystal composition contains only the compound (C) having one crosslinkable functional group (y) and the compound (D) having one crosslinkable functional group (z) as the crosslinkable functional group-containing compound. The proportion of the compound (D) is less than or equal to the compound (C), the compound (C) having one crosslinkable functional group (y) and the two crosslinkable functional groups (z). When only the compound (F) is contained, the ratio of the compound (F) is preferably ½ mol or less with respect to the compound (C). Most preferably, no crosslinkable functional group substantially remains in the cross-linked polymer liquid crystal. Therefore, the ratio of both crosslinkable functional groups in the liquid crystal composition is substantially equivalent. preferable. The proportion of the compound having a highly active crosslinkable functional group (z) in the liquid crystal composition is equal to or less than that of the compound having the crosslinkable functional group (y), and the compound present in the liquid crystal composition 1 mol% or more, especially 3 mol% or more is preferable with respect to the total number of moles of (A) to (F). A more desirable ratio is from 5 to 25 mol%.

  The liquid crystal composition of the present invention may also contain a component that is not any of the compounds (A) to (F). In particular, in order to carry out the photopolymerization reaction, it is usually essential to add a photopolymerization initiator. Examples of the photopolymerization initiator include acetophenones, benzophenones, benzoins, benzyls, Michler ketones, benzoin alkyl ethers, benzyl dimethyl ketals, and thioxanthones. Moreover, you may use together 2 or more types of photoinitiators as needed. 0.1-10 mass% is preferable with respect to a liquid-crystal composition, and, as for the usage-amount of a photoinitiator, 0.2-2 mass% is especially preferable.

  In addition, the liquid crystal composition of the present invention includes a non-photopolymerizable liquid crystal compound, a non-photopolymerizable liquid crystal compound for the purpose of improving desired properties such as phase stabilization, viscosity adjustment, and birefringence of the liquid crystal composition. You may mix | blend a non-liquid crystal compound, a pigment | dye, etc. Examples of non-photopolymerizable liquid crystal compounds include compounds that exhibit liquid crystallinity at low temperatures, low viscosity compounds for low temperatures, compounds that improve refractive index anisotropy, compounds that improve dielectric anisotropy, and cholesteric properties. There are compounds to be imparted.

The crosslinked polymer liquid crystal of the present invention is produced by photopolymerizing the liquid crystal composition of the present invention in a state where the liquid crystal composition is aligned, and then heating the resulting polymer to perform a crosslinking reaction.
The alignment of the liquid crystal composition is preferably carried out by bringing the liquid crystal composition into contact with the surface of the support whose surface has been subjected to alignment treatment. In particular, it is preferably performed by filling a liquid crystal composition in a cell constituted by two substrates whose surfaces are subjected to alignment treatment, and bringing the liquid crystal composition into contact with the two alignment-treated surfaces. Next, the aligned liquid crystal composition is irradiated with light to perform photopolymerization to form an aligned polymer liquid crystal. After photopolymerization, the produced polymer liquid crystal is heated and crosslinked to obtain a target crosslinked polymer liquid crystal. The obtained crosslinked polymer liquid crystal can be peeled off from the support and used for various purposes, and can be used for various purposes while being integrated with the support.

  The support is preferably a support made of a material such as glass or plastic. In order to perform photopolymerization between two supports, at least one of the supports is preferably a support that is transparent to the light irradiated for photopolymerization. The two supports are preferably sealed structures, that is, cells. The alignment treatment of the support surface can be performed by rubbing, oblique deposition of an alignment agent, or the like. Orientation by rubbing can be performed by directly rubbing the support surface with natural fibers such as cotton and wool, synthetic fibers such as polyamide and polyester, and also from polyimide or polyamide previously formed on the support surface. It can also carry out by rubbing the surface of the orientation agent thin film layer to be rubbed with the above-mentioned fibers or the like. The distance between the two supports can be adjusted by the sealing material, and can be adjusted by beads having a predetermined diameter added to the liquid crystal composition.

In order to keep the liquid crystal composition in a liquid crystal state, the atmospheric temperature during photopolymerization is not more than the phase transfer temperature of the nematic phase-isotropic phase (hereinafter also referred to as T _c ) when the composition is in a liquid state. Hold at temperature. Since the refractive index anisotropy becomes small at a temperature close to T _c , the ambient temperature is preferably set to (T _c −10) ° C. or lower. Further, the atmospheric temperature during the photopolymerization is a temperature at which the crosslinking reaction does not substantially occur, and it is necessary that the crosslinking reaction does not disturb the alignment of the liquid crystal composition prior to the photopolymerization. Usually, it is preferable to perform photopolymerization at 60 ° C. or lower, particularly 40 ° C. or lower. As light for performing this photopolymerization, ultraviolet rays or visible rays can be used, and ultraviolet rays are particularly preferable.

The polymer liquid crystal produced by photopolymerization is then crosslinked by heating. The produced polymer liquid crystal is oriented, and it is desirable that the orientation is not disturbed as much as possible during the heat crosslinking. Therefore, the heating temperature at the time of crosslinking is preferably equal to or lower than T _c of the polymer liquid crystal (which is higher than T _{c of the} liquid crystal composition). The crosslinking temperature is preferably higher than the photopolymerization temperature and lower than the _{Tc of the} polymer liquid crystal, and is usually 50 to 150 ° C, particularly 60 to 120 ° C. Is preferred. This crosslinking step may be performed on the polymer liquid crystal separated from the support. For example, a film-like uncrosslinked polymer liquid crystal is produced by photopolymerization on a support or between supports, and then the obtained uncrosslinked polymer liquid crystal is separated from the support by peeling or the like. The film can be taken out and the film can be crosslinked by heating to obtain a crosslinked polymer liquid crystal film.

  The crosslinked polymer liquid crystal obtained by the present invention is suitable as a material for an optical element. Such an optical element is particularly preferably an optical element that is used while the crosslinked polymer liquid crystal produced in the cell is integrated with the cell. Therefore, the present invention is a method for producing a crosslinked polymer liquid crystal in which a liquid crystal composition is photopolymerized and crosslinked in this cell. That is, the present invention also includes an alignment step in which a liquid crystal composition is filled in a cell and the liquid crystal composition is aligned, a photopolymerization step in which the aligned liquid crystal composition is irradiated with light and photopolymerized, and the photopolymerization. And a crosslinking step of performing a crosslinking reaction by heating the polymer produced by the above method.

  Examples of the optical element using the crosslinked polymer liquid crystal in the present invention include a retardation film and a polarization hologram. For example, in the polarization hologram, the light utilization efficiency is high, and the temperature dependence of the diffraction efficiency is small, so that an excellent optical head device can be produced using this.

  Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples.

  In addition, the acquisition of the compound used below and the synthesis method are the compounds (C-1), (F-1) and (F-2) manufactured by Aldrich, and the compound (E-1) manufactured by Showa Denko. It was used.

  Compound (A-1) is a method described in JP-A No. 11-10055, compound (A-2) is a method described in JP-A No. 2001-89529, and compound (B-1) is Macromol. Chem. Phys., 197, 1919-1935, (1996), compound (A-4) is the method described in JP-A-11-10055, and compound (A-5) is The compound (G) was synthesized by the method described in JP-A-2001-270848 by the method described in JP-A-11-10055.

Compound (A-3) was synthesized by the following route.

<Example 1>
A composition containing the following compound (C-1), compound (A-1), compound (A-2), and compound (A-3) was adjusted at a blending ratio (molar ratio) shown in Table 1, 0.5 equivalent of the compound (F-1) was added to the compound (C-1) to obtain a liquid crystal composition (a). The liquid crystal composition (A) showed supercooled liquid crystal (nematic phase), and _Tc was 74 ° C.

  After applying polyimide, which is an alignment agent, onto a glass plate with a spin coater, heat-treating, and using a substrate that has been rubbed in a certain direction with nylon cloth as a support, two supports so that the aligned surfaces face each other Were stuck together using an adhesive via a bead spacer to produce a cell with a support spacing of 11.5 μm.

  Into this cell, 2% by weight of a photopolymerization initiator (Irgacure 819: manufactured by Ciba Geigy) was added at 95 ° C. to the liquid crystal composition (I).

Next, after carrying out photopolymerization by irradiating ultraviolet rays having a wavelength of 350 nm and an intensity of 60 mW / cm ² at room temperature for 90 seconds, the polymer liquid crystal film ( B) This polymer liquid crystal was horizontally aligned in the rubbing direction of the substrate, was transparent in the visible region, and was not scattered.

<Example 2>
A liquid crystal composition (b) is obtained by the same operation as in Example 1 except that the following compound (F-2) is used instead of the compound (F-1) of the liquid crystal composition (a). It was. The liquid crystal composition (b) showed supercooled liquid crystal (nematic phase), and _Tc was 73 ° C.

  Then, the same photopolymerization and crosslinking treatment as in Example 1 were performed to obtain a polymer liquid crystal film (b). This polymer liquid crystal film (b) was horizontally aligned in the rubbing direction of the substrate, was transparent in the visible region, and no scattering was observed.

<Example 3>
A liquid crystal composition (C) containing the following compound (A-4), compound (A-3), compound (C-1), and compound (F-2) was prepared. The liquid crystal composition (C) showed supercooled liquid crystal (nematic phase), and _Tc was 66 ° C.

  Thereafter, the same photopolymerization and crosslinking treatment as in Example 1 were performed to obtain a polymer liquid crystal film (c). This polymer liquid crystal was horizontally aligned in the rubbing direction of the substrate, was transparent in the visible region, and was not scattered.

<Example 4>
Example 3 is the same as Example 3 except that the following compound (B-1) and compound (D-1) are used instead of the compound (C-1) and the compound (F-2) of the liquid crystal composition (c). Operation was performed to obtain a liquid crystal composition (d). The liquid crystal composition (d) showed supercooled liquid crystal (nematic phase) and _Tc was 59 ° C.

  Then, except having poured into the cell at 90 degreeC, the same photopolymerization and crosslinking process as Example 1 were performed, and the polymer liquid crystal film (d) was obtained. This polymer liquid crystal was horizontally aligned in the rubbing direction of the substrate, was transparent in the visible region, and was not scattered.

<Example 5>
A liquid crystal composition (e) containing the following compound (A-5), compound (A-4), compound (A-3), compound (B-1), and compound (D-1) was prepared. The liquid crystal composition (e) showed supercooled liquid crystal (nematic phase), and _Tc was 30 ° C.

  Then, except having poured into the cell at 90 degreeC, the same photopolymerization and crosslinking process as Example 1 were performed, and the polymer liquid crystal film (e) was obtained. This polymer liquid crystal was horizontally aligned in the rubbing direction of the substrate, was transparent in the visible region, and was not scattered.

<Example 6>
A liquid crystal composition (f) containing the compound used in Example 5 at the ratio shown in Table 1 was prepared. The liquid crystal composition (f) showed supercooled liquid crystal (nematic phase) and _Tc was 59 ° C.

  Then, except having poured into the cell at 90 degreeC, the same photopolymerization and crosslinking process as Example 1 were performed, and the polymer liquid crystal film (f) was obtained. This polymer liquid crystal was horizontally aligned in the rubbing direction of the substrate, was transparent in the visible region, and was not scattered.

<Comparative Example 1>
A liquid crystal composition (g) containing the following compound (C-1), compound (A-1), compound (A-2), and compound (A-3) was prepared. The liquid crystal composition (g) exhibited supercooled liquid crystal (nematic phase), and _Tc was 88 ° C.

  Thereafter, photopolymerization was carried out in the same manner as in Example 1 to obtain a polymer liquid crystal film (g). This polymer liquid crystal film was horizontally aligned in the rubbing direction of the substrate, was transparent in the visible region, and was not scattered.

<Comparative example 2>
A liquid crystal composition (h) containing the following compound (B-1) and compound (A-3) was prepared. The liquid crystal composition (h) showed a nematic liquid crystal, and its temperature range was 69 ° C to 78 ° C.

  Then, except having injected into the cell at 90 degreeC, the same photopolymerization and crosslinking process as Example 1 were performed, and the polymer liquid crystal film (h) was obtained. This polymer liquid crystal was horizontally aligned in the rubbing direction of the substrate, was transparent in the visible region, and was not scattered.

<Comparative Example 3>
A liquid crystal composition (Li) containing the following compound (A-5), compound (A-4), compound (A-3), and compound (G) was prepared. The liquid crystal composition (Li) showed a nematic liquid crystal, and its temperature range was 44 ° C to 79 ° C.

  Then, except having poured into the cell at 90 degreeC, the same photopolymerization and crosslinking process as Example 1 were performed, and the polymer liquid crystal film (re) was obtained. This polymer liquid crystal was horizontally aligned in the rubbing direction of the substrate, was transparent in the visible region, and was not scattered.

<Comparative example 4>
A liquid crystal composition (nu) was prepared using the compounds used in Comparative Example 3 in the proportions shown in Table 1. The liquid crystal composition (nu) showed supercooled liquid crystal (T _c = 50 ° C.). However, crystals were deposited along with the transition to the liquid crystal phase, so that a stable liquid crystal phase could not be maintained, and a polymer could not be formed by photopolymerization.

Test Example For the liquid crystal compositions and polymer liquid crystal films of Examples 1 to 6 and Comparative Examples 1 to 3, the ratio V [mol%] of the crosslinkable compound in the total amount of the liquid crystal composition, the liquid crystal composition was crosslinked after polymerization. Δn in light of wavelength 633 nm at 30 ° C. and 80 ° C. of the obtained polymer liquid crystal film, reduction rate (R) of birefringence index (Δn) defined by the following formula, longest compound in liquid crystal composition The molecular length (L ₁ ), the molecular length (L ₂ ) of the crosslinking site, and the ratio thereof (L ₂ / L ₁ ) were measured. The results are summarized in Table 2.

R = (1− (Δn (80 ° C.) / Δn (30 ° C.))) × 100
Note that Δn is a sample placed between two orthogonal polarizing plates so that the orientation direction is 45 ° with respect to the polarization direction, and the transmittance of probe light (He-Ne laser, wavelength: 633 nm) that passes through the sample. The Δn was calculated from the following formula.

T = I / I ₀ = sin ² (πΔnd / λ)
Here, T is the transmittance, I ₀ is the incident light intensity, I is the transmitted light intensity, λ is the wavelength of the probe light, Δn is the birefringence at the wavelength of the probe light, and d is the thickness of the sample.

  From Table 2, in the liquid crystal compositions of Examples 1 to 6, a polymer liquid crystal film having a reduction rate R of the birefringence (Δn) of 10% or less is obtained in the range of V of 20 to 60 mol%. Yes. On the other hand, in Comparative Examples 1 and 2 that do not contain a crosslinkable compound, the reduction rate R of the birefringence index (Δn) is as large as 20% or more.

  The liquid crystal composition of the present invention and the method for producing a polymer liquid crystal using the liquid crystal composition are suitably used for optical elements such as a retardation plate and a polarization hologram, for example.

Claims (7)

A polymerizable liquid crystal composition containing two or more compounds selected from the following compounds (A) to (F), the composition comprising a mesogenic group (x), a crosslinkable functional group (y) and a second compound. A liquid crystal composition comprising a combination containing a crosslinkable functional group (z).
(However, the following crosslinkable functional group (y) and the following second crosslinkable functional group (z) do not substantially react under light irradiation in photopolymerization and both react by heating. (Combined combination)
(1): Compound (A) having a mesogenic group (x) and a photopolymerizable functional group.
(2): Compound (B) having a mesogenic group (x), a crosslinkable functional group (y), and a photopolymerizable functional group.
(3): Compound (C) having a crosslinkable functional group (y) and a photopolymerizable functional group.
(4): Compound (D) having a second crosslinkable functional group (z) and a photopolymerizable functional group.
(5): Compound (E) having a mesogenic group (x), a second crosslinkable functional group (z), and a photopolymerizable functional group.
(6): A compound (F) that does not photopolymerize and has two or more second crosslinkable functional groups (z).   2. The liquid crystal composition according to claim 1, wherein the polymerizable liquid crystal composition is a combination in which the crosslinkable functional group (y) and the second crosslinkable functional group (z) are present in substantially equivalent amounts.   The liquid crystal composition according to claim 1 or 2, wherein the combination of the crosslinkable functional group (y) and the second crosslinkable functional group (z) is a combination bonded by an addition reaction.   The combination of a crosslinkable functional group (y) and a 2nd crosslinkable functional group (z) is as described in any one of Claims 1-3 whose one is an isocyanate group and the other is a hydroxyl group or an amino group. Liquid crystal composition.   The polymerizable liquid crystal composition is at least one selected from compound (A), at least one selected from compound (B) and compound (C), and at least one selected from compound (D) and compound (F). The liquid crystal composition according to claim 1, comprising a combination of seeds.   A polymer, wherein the liquid crystal composition according to any one of claims 1 to 5 is photopolymerized in a state where the liquid crystal composition is aligned, and then the resulting polymer is heated to perform a crosslinking reaction. Liquid crystal manufacturing method.   An alignment step of filling the liquid crystal composition according to any one of claims 1 to 5 into a cell and aligning the liquid crystal composition, and photopolymerization by photoirradiating the aligned liquid crystal composition with light. A method for producing a polymer liquid crystal comprising: a step; and a crosslinking step in which a polymer produced by the photopolymerization is heated to perform a crosslinking reaction.