Patent Grant
11634638
The present invention relates to a liquid crystal composition, a reflective layer, a method for producing a reflective layer, and a copolymer.
A cholesteric liquid crystalline phase is a liquid crystalline phase in which liquid crystal molecules are aligned in a helical manner and which has a periodic structure with a refractive index anisotropy in a helical axis direction, and has a property of reflecting light corresponding to a helical pitch on a plane perpendicular to the helical axis. In recent years, a layer in which an alignment state of the cholesteric liquid crystalline phase is fixed (hereinafter, also referred to as a “layer formed by fixing a cholesteric liquid crystalline phase”) has been applied to various fields such as a light reflecting plate and a screen. Due to the nature of the cholesteric liquid crystalline phase, either dextrorotatory circularly polarized light or levorotatory circularly polarized light is selectively reflected in a case where light is incident from the normal direction of the surface of the layer formed by fixing a cholesteric liquid crystalline phase.
The layer formed by fixing a cholesteric liquid crystalline phase as described above is formed, for example, by applying a liquid crystal composition containing a liquid crystal compound on a transparent base material to form a composition layer, and then fixing the liquid crystal compound contained in the composition layer to a desired alignment state. At that time, the liquid crystal compound in the composition layer is aligned by receiving an alignment regulating force from the base material interface and the air interface.
In addition, a compound containing a fluorine chain is generally known as an alignment control agent for regulating the alignment on the air interface side. For example, JP2006-016599A discloses an example in which uniaxial alignment of a polymerizable rod-like liquid crystal composition is controlled by using a (meth)acrylic copolymer having a molecular weight of 10,000 or more containing a mesogen moiety composed of two rings and a fluorine atom-containing moiety as an alignment control agent.
By the way, in recent years, attempts have been made to further improve the diffuse reflectivity (property of reflecting light in various directions) of a layer formed by fixing a cholesteric liquid crystalline phase. For example, a method of making the direction of a helical axis of a liquid crystal compound aligned in a cholesteric liquid crystalline phase state non-uniform in a layer has been studied.
The present inventors formed a layer in which a cholesteric liquid crystalline phase was fixed using a liquid crystal composition containing the (meth)acrylic copolymer disclosed in the foregoing JP2006-016599A as an alignment control agent, and examined the diffuse reflectivity thereof. As a result, it was found that the diffuse reflectivity did not satisfy the level required recently.
In addition, the present inventors also studied the performance of a coating film formed from the liquid crystal composition, and found that it is necessary to further improve the planarity. In other words, the present inventors found that it is necessary to further suppress drying unevenness and foreign matter that appear on the surface of the coating film.
In view of the above circumstances, an object of the present invention is to provide a liquid crystal composition which has excellent planarity in a case of being formed into a coating film and is also capable of forming a reflective layer having excellent diffuse reflectivity.
Further, an object of the present invention is to provide a reflective layer that is formed using the liquid crystal composition.
Further, an object of the present invention is to provide a method for producing a reflective layer using the liquid crystal composition.
Further, an object of the present invention is to provide a copolymer that can be used as an alignment control agent for a liquid crystal compound.
As a result of extensive studies to achieve the foregoing objects, the present inventors have found that the foregoing objects can be achieved in a case where the liquid crystal composition contains a polymerizable liquid crystal compound and a copolymer having a predetermined structure. The present invention has been completed based on these findings.
That is, it has been found that the foregoing objects can be achieved by the following configuration.
[1] A liquid crystal composition comprising:
a polymerizable liquid crystal compound; and
a copolymer containing a repeating unit containing a group represented by General Formula (X1) which will be described later and a repeating unit derived from a monomer represented by General Formula (Y1) which will be described later, and having a weight-average molecular weight of less than 10,000.
[2] The liquid crystal composition according to [1], in which a content of the repeating unit containing a group represented by General Formula (X1) is 25% by mass or more with respect to all the repeating units of the copolymer.
[3] The liquid crystal composition according to [1] or [2], in which the repeating unit containing a group represented by General Formula (X1) is a repeating unit derived from a monomer represented by General Formula (X2) which will be described later.
[4] The liquid crystal composition according to any one of [1] to [3], in which Z1 is an alkyl group having 1 to 20 carbon atoms in which —CH2— may be substituted with —O—, —CO—O—, —O—CO—, or —CO—, an alkenyl group having 2 to 20 carbon atoms in which —CH2— may be substituted with —O— or —CO—, a halogen atom, a cyano group, an acetyl group, a formyl group, a carboxy group, or a hydroxy group.
[5] The liquid crystal composition according to any one of [1] to [4], in which, in General Formula (Y1),
A1 and A2 each independently represent a 1,2-phenylene group, a 1,3-phenylene group, a 1,4-phenylene group, or a 1,4-cyclohexylene group, each of which may have a substituent,
X1 represents a single bond, —O—, —CO—O—, or —O—CO—,
one or more of Y1's represent —CO—O— or —O—CO—, and
Z1 represents an alkyl group having 1 to 8 carbon atoms in which —CH2— may be substituted with —O—, —O—CO—O—, —O—CO—, or —CO—, an alkenyl group having 2 to 8 carbon atoms in which —CH2— may be substituted with —O— or —CO—, a halogen atom, or a cyano group.
[6] The liquid crystal composition according to any one of [1] to [5], in which a content of the repeating unit derived from a monomer containing two or more polymerizable groups in the copolymer is less than 5 mol % with respect to all the repeating units of the copolymer.
[7] The liquid crystal composition according to any one of [1] to [6], in which the copolymer has a weight-average molecular weight of less than 9,000.
[8] The liquid crystal composition according to any one of [1] to [7], in which a content of the copolymer is 0.01% by mass or more and less than 5% by mass with respect to a content of the polymerizable liquid crystal compound.
[9] The liquid crystal composition according to any one of [1] to [8], further comprising:
a chiral agent.
[10] A reflective layer obtained by polymerizing the liquid crystal composition according to any one of [1] to [9].
[11] A method for producing a reflective layer, comprising:
a step 1 of forming a composition layer on a transparent base material not subjected to a uniaxial alignment treatment using the liquid crystal composition according to any one of [1] to [9];
a step 2 of aligning a liquid crystal compound contained in the composition layer into a cholesteric liquid crystalline phase state; and
a step 3 of fixing the cholesteric liquid crystalline phase after the step 2.
[12] A copolymer comprising:
a repeating unit derived from a monomer represented by General Formula (X2) which will be described later; and
a repeating unit derived from a monomer represented by General Formula (Y1) which will be described later,
in which the copolymer has a weight-average molecular weight of less than 10,000.
According to the present invention, it is possible to provide a liquid crystal composition which has excellent planarity in a case of being formed into a coating film and is also capable of forming a reflective layer having excellent diffuse reflectivity.
Further, according to the present invention, it is possible to provide a reflective layer that is formed using the liquid crystal composition.
Further, according to the present invention, it is possible to provide a method for producing a reflective layer using the liquid crystal composition.
Further, according to the present invention, it is possible to provide a copolymer that can be used as an alignment control agent for a liquid crystal compound.
Hereinafter, the present invention will be described in detail.
The description of the constituent elements described below may be made based on representative embodiments of the present invention, but the present invention is not limited to such embodiments.
In the present specification, the numerical range expressed by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value, respectively.
Further, in the present specification, the term “(meth)acrylate” is a notation expressing both acrylate and methacrylate, the term “(meth)acryloyl group” is a notation expressing both acryloyl group and methacryloyl group, and the term “(meth)acrylic” is a notation expressing both acrylic and methacrylic.
A feature of the liquid crystal composition according to the embodiment of the present invention is that it contains a copolymer which will be described later (hereinafter, also referred to as a “specific copolymer”). Due to including the specific copolymer, the liquid crystal composition according to the embodiment of the present invention has excellent planarity in a case of being formed into a coating film and is also capable of forming a reflective layer having excellent diffuse reflectivity.
Although the action mechanism of the present invention is not clear, the present inventors speculate as follows.
It is considered that, in a case where a composition layer of a liquid crystal composition containing a specific copolymer and a liquid crystal compound is formed on a base material, the specific copolymer is likely to be unevenly distributed at the interface on the air interface side due to the presence of a repeating unit containing a group represented by General Formula (X1) which will be described later, and controls the alignment of the liquid crystal compound from the air interface side. In addition, it is considered that a repeating unit derived from a monomer represented by General Formula (Y1) which will be described later in the specific copolymer has a structure in which a mesogen moiety contained in the repeating unit is easily movable and has excellent compatibility with a liquid crystal compound, due to structural characteristics thereof. It is considered that, due to the synergism of these action mechanisms, the liquid crystal compound is controlled in alignment by the copolymer, and therefore the direction of the helical axis of the helically aligned liquid crystal compound becomes non-uniform in the layer, in a case where the liquid crystal compound in the composition layer is aligned into a cholesteric liquid crystalline phase state.
As a result, the layer formed by fixing a cholesteric liquid crystalline phase (that is, the layer in which the alignment state is fixed (hereinafter, also referred to as “CL layer”) has a cholesteric liquid crystal structure, and the cholesteric liquid crystal structure gives a stripe pattern of a bright portion (continuous line) and a dark portion (continuous line) in a cross-sectional view of the CL layer observed by a scanning electron microscope (SEM), and therefore has a region in which the angle between the normal of a line formed by at least one dark portion and the surface of the CL layer periodically or irregularly changes (note that the region in which the angle between the normal of a line formed by at least one dark portion and the surface of the CL layer periodically changes can be confirmed in a cross-sectional SEM image, for example, as a region in which the bright portion and the dark portion have a wave-like structure). Therefore, light incident from the normal direction of the CL layer is reflected by the CL layer, and the light can be diffusely reflected in various directions, not in limited directions.
On the other hand, in a case where the direction of the helical axis of the helically aligned liquid crystal compound is uniform in the layer in the state of the cholesteric liquid crystalline phase, the cholesteric liquid crystal structure gives a stripe pattern of a bright portion (continuous line) and a dark portion (continuous line) in a cross-sectional view of the CL layer observed by a scanning electron microscope, and therefore both the bright portion and the dark portion are linear so as to be parallel to the surface of the CL layer. Therefore, in a case where light is incident from the normal direction of the CL layer, the light is reflected in the normal direction, but is hardly reflected in the oblique direction, which results in poor diffuse reflectivity.
In addition, according to the foregoing specific copolymer, it has also been confirmed that the planarity of the coating film of the composition layer of the liquid crystal composition is improved owing to the fact that the specific copolymer has a weight-average molecular weight of less than a predetermined value and the fact that the specific copolymer contains a repeating unit containing a group represented by General Formula (X1). In particular, as will be described later, it has been confirmed that, in a case where the content of the repeating unit containing a group represented by General Formula (X1) is 25% by mass with respect to all the repeating units of the specific copolymer, not only the planarity of the composition layer of the liquid crystal composition is excellent, but also the diffuse reflectivity of the reflective layer is more excellent.
(Specific Copolymer)
Hereinafter, the specific copolymer will be described.
The specific copolymer contains a repeating unit containing a group represented by General Formula (X1) which will be described later and a repeating unit derived from a monomer represented by General Formula (Y1) which will be described later, and has a weight-average molecular weight of less than 10,000.
Hereinafter, each of repeating units contained in the specific copolymer will be described.
<Repeating Unit Containing Group Represented by General Formula (X1)>
The specific copolymer contains a repeating unit containing a group represented by General Formula (X1).
Hereinafter, General Formula (X1) will be described.
*-L11-CF2Xa (X1)
In Formula (X1), L11 represents a single bond or a perfluoroalkylene group having 1 to 6 carbon atoms which may contain —O—. The perfluoroalkylene group having 1 to 6 carbon atoms which may contain —O— and is represented by L11 may be linear or branched. Examples of the branched perfluoroalkylene group having 1 to 6 carbon atoms which may contain —O— and is represented by L11 include, in a case where the number of carbon atoms is 4, —CF(CF3)OCF2CF2—, —CF2CF2OCF(CF3)—, —CF(CF3)CF2CF2CF2—, and —CF2CF2CF(CF3)—.
As the perfluoroalkylene group having 1 to 6 carbon atoms which may contain —O— and is represented by L11, a perfluoroalkylene group having 1 to 6 carbon atoms is preferable, and a perfluoroalkylene group having 4 to 6 carbon atoms is more preferable.
Xa represents a hydrogen atom or a fluorine atom. Xa is preferably a fluorine atom.
* represents a bonding position.
In a case where Xa represents a hydrogen atom, L11 is preferably a perfluoroalkylene group having 1 to 6 carbon atoms which may contain —O—.
The repeating unit containing a group represented by General Formula (X1) is preferably a repeating unit derived from a monomer represented by Formula (X2).
In General Formula (X2), R11 represents a hydrogen atom or a methyl group. R11 is preferably a hydrogen atom.
R12 represents a monovalent group including the group represented by General Formula (X1).
The monovalent group including the group represented by General Formula (X1), which is represented by R12, is not particularly limited, and examples thereof include General Formula (X3).
*-L12-L11-CF2Xa (X3)
In General Formula (X3), L12 is a single bond or an alkylene group having 1 to 30 carbon atoms in which —CH2— may be substituted with —O—. The number of carbon atoms in the alkylene group having 1 to 30 carbon atoms in which —CH2— may be substituted with —O—, which is represented by L12, is preferably 1 to 20 and more preferably 1 to 10. The alkylene group may be linear, branched, or cyclic. L12 may further have a substituent. Examples of the substituent include a hydroxy group.
In General Formula (X3), L11 and Xa each have the same definition as L11 and Xa in General Formula (X1), and the suitable aspects thereof are also the same.
In General Formula (X3), * represents a bonding position.
From the viewpoint of reducing the surface energy of the liquid crystal composition and enhancing the effects of the present invention, the monomer represented by General Formula (X3) is preferably a monomer represented by General Formula (X4).
In General Formula (X4), R11 represents a hydrogen atom or a methyl group. R11 is preferably a hydrogen atom.
ma represents an integer of 0 or more. The upper limit of ma is, for example, 20 or less. ma is preferably an integer of 1 to 10, more preferably an integer of 1 to 6, and still more preferably an integer of 1 to 4.
na represents an integer of 1 to 6. na is more preferably an integer of 3 to 5.
Xa represents a hydrogen atom or a fluorine atom. Xa is preferably a fluorine atom.
Examples of the monomer represented by General Formula (III) include 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3,3-pentafluoropropyl (meth)acrylate, 2-(perfluorobutyl)ethyl (meth)acrylate, 2-(perfluorohexyl)ethyl (meth)acrylate, 2-(perfluoroheptyl)ethyl (meth)acrylate, 2-(perfluoro-3-methylbutyl)ethyl (meth)acrylate, 2-(perfluoro-5-methylhexyl)ethyl (meth)acrylate, 1H,1H,3H-tetrafluoropropyl (meth)acrylate, 1H,1H,5H-octafluoropentyl (meth)acrylate, 1H,1H,7H-dodecafluoroheptyl (meth)acrylate, 1H-1-(trifluoromethyl)trifluoroethyl (meth)acrylate, 1H,1H,3H-hexafluorobutyl (meth)acrylate, 3-perfluorobutyl-2-hydroxypropyl (meth)acrylate, 3-perfluorohexyl-2-hydroxypropyl (meth)acrylate, 3-(perfluoro-3-methylbutyl)-2-hydroxypropyl (meth)acrylate, and 3-(perfluoro-5-methylhexyl)-2-hydroxypropyl (meth)acrylate.
The content of the repeating unit containing a group represented by General Formula (X1) in the specific copolymer (in a case where there are a plurality of repeating units containing a group represented by General Formula (X1), the total content of the plurality of repeating units) is, for example, 5% by mass or more with respect to all the repeating units of the specific copolymer, and is preferably 25% by mass or more from the viewpoint that the composition layer of the liquid crystal composition has more excellent planarity and the reflective layer has more excellent diffuse reflectivity. The upper limit value of the content of the repeating unit containing a group represented by General Formula (X1) is, for example, 70% by mass or less and preferably 60% by mass or less with respect to all the repeating units of the specific copolymer.
<Repeating Unit Derived from Monomer Represented by General Formula (Y1)>
In Formula (Y1), R1 represents a hydrogen atom or a methyl group. R1 is preferably a hydrogen atom.
R2 represents —O— or —NR3— where R3 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. R2 is preferably —O—. Incidentally, R3 is preferably a hydrogen atom.
L1 represents an alkylene group having 1 to 20 carbon atoms in which —CH2— may be substituted with —O—, —S—, or —CO—. In addition, in L1, the position adjacent to X1 is preferably a carbon atom.
The number of carbon atoms in the alkylene group having 1 to 20 carbon atoms in which —CH2— may be substituted with —O—, —S—, or —CO—, which is represented by L1, is not particularly limited, but is preferably 1 to 15, more preferably 1 to 10, and still more preferably 1 to 6.
In particular, the alkylene group having 1 to 20 carbon atoms in which —CH2— may be substituted with —O—, —S—, or —CO—, which is represented by L1, is preferably an alkylene group having 1 to 10 carbon atoms and more preferably an alkylene group having 1 to 6 carbon atoms.
The alkylene group having 1 to 20 carbon atoms in which —CH2— may be substituted with —O—, —S—, or —CO—, which is represented by L1, may further have a substituent.
X1 and Y1 each independently represent a single bond, —O—, —CO—O—, —O—CO—, —O—CO—O—, —O—CH2, —CH2—O—, —C═N—, —N═C—, —CO—O—CH2CH2, or —CH2CH2—CO—O—.
X1 is preferably a single bond, —O—, —CO—O—, or —O—CO—, more preferably a single bond or —O—, and still more preferably —O— from the viewpoint that the diffuse reflectivity of the reflective layer is more excellent.
Y1 is preferably a single bond, —CO—O—, or —O—CO— from the viewpoint that the diffuse reflectivity of the reflective layer is more excellent, and it is preferred that one or more of Y1's represent —CO—O— or —O—CO—.
A1 and A2 each independently represent a phenylene group, a cyclohexylene group, or a naphthylene group, each of which may have a substituent.
In particular, from the viewpoint that the diffuse reflectivity of the reflective layer is more excellent, A1 is preferably a 1,2-phenylene group, a 1,3-phenylene group, a 1,4-phenylene group, or a 1,4-cyclohexylene group, each of which may have a substituent, and more preferably a 1,4-phenylene group which may have a substituent.
In particular, from the viewpoint that the diffuse reflectivity of the reflective layer is more excellent, A2 is preferably a 1,2-phenylene group, a 1,3-phenylene group, a 1,4-phenylene group, or a 1,4-cyclohexylene group, each of which may have a substituent, and more preferably a 1,4-phenylene group which may have a substituent.
The substituents that A1 and A2 may have are not particularly limited, and examples thereof include an alkyl group having 1 to 20 carbon atoms in which —CH2— may be substituted with —O—, —CO—O—, or —O—CO—.
Z1 represents an alkyl group having 1 to 20 carbon atoms in which —CH2— may be substituted with —O—, —CO—O—, —O—CO—O—, or —CO—, an alkenyl group having 2 to 20 carbon atoms in which —CH2— may be substituted with —O— or —CO—, a halogen atom, a cyano group, an acetyl group, a formyl group, a carboxy group, a hydrogen atom, or a hydroxy group.
The number of carbon atoms in the alkyl group having 1 to 20 carbon atoms in which —CH2— may be substituted with —O—, —CO—O—, —O—CO—, or —CO—, which is represented by Z1, is preferably 1 to 10, more preferably 1 to 8, and still more preferably 1 to 6. The alkyl group having 1 to 20 carbon atoms in which —CH2— may be substituted with —O—, —CO—O—, —O—CO—, or —CO—, which is represented by Z1, may be linear, branched, or cyclic.
The alkyl group having 1 to 20 carbon atoms in which —CH2— may be substituted with —O—, —CO—O—, —O—CO—O—, or —CO—, which is represented by Z1, is preferably an alkyl group having 1 to 10 carbon atoms in which —CH2— may be substituted with —CO—O— or —O—CO—, and more preferably an alkyl group having 1 to 8 carbon atoms in which —CH2— may be substituted with —CO—O— or —O—CO—.
The number of carbon atoms in the alkenyl group having 2 to 20 carbon atoms in which —CH2— may be substituted with —O— or —CO—, which is represented by Z1, is preferably 2 to 10, more preferably 2 to 8, and still more preferably 2 to 6. The alkenyl group having 2 to 20 carbon atoms in which —CH2— may be substituted with —O— or —CO—, which is represented by Z1, may be linear, branched, or cyclic.
The alkenyl group having 2 to 20 carbon atoms in which —CH2— may be substituted with —O— or —CO—, which is represented by Z1, is preferably an alkenyl group having 2 to 10 carbon atoms in which —CH2— may be substituted with —O— or —CO— and more preferably an alkenyl group having 2 to 8 carbon atoms in which —CH2— may be substituted with —O— or —CO—.
From the viewpoint that the diffuse reflectivity of the reflective layer is more excellent, Z1 is preferably an alkyl group having 1 to 20 carbon atoms in which —CH2— may be substituted with —O—, —CO—O—, —O—CO—, or —CO—, or —CO—, an alkenyl group having 2 to 20 carbon atoms in which —CH2— may be substituted with —O— or —CO—, a halogen atom, a cyano group, an acetyl group, a formyl group, a carboxy group, or a hydroxy group, and more preferably an alkyl group having 1 to 8 carbon atoms in which —CH2— may be substituted with —CO—O— or —O—CO—, an alkenyl group having 2 to 8 carbon atoms in which —CH2— may be substituted with —O— or —CO—, a halogen atom, or a cyano group. That is, Z1 is preferably other than a hydrogen atom.
In addition, the alkyl group having 1 to 20 carbon atoms in which —CH2— may be substituted with —O—, —CO—O—, —O—CO—, or —CO—, and the alkenyl group having 2 to 20 carbon atoms in which —CH2— may be substituted with —O— or —CO—, each of which is represented by Z1, may further have a substituent.
m represents 0 or 1. m is preferably 1 from the viewpoint that the diffuse reflectivity of the reflective layer is more excellent.
n represents an integer of 2 to 4. n is preferably 2 or 3 from the viewpoint of more excellent planarity.
In General Formula (Y1), a plurality of A1's and a plurality of Y1's may be the same as or different from each other.
Hereinafter, specific examples of the monomer represented by General Formula (Y1) will be described, but the present invention is not limited thereto.
The content of the repeating unit derived from General Formula (Y1) in the specific copolymer (in a case where there are a plurality of repeating units derived from General Formula (Y1), the total content of the plurality of repeating units) is, for example, 40% by mass or more, preferably 60% by mass or more, and more preferably 65% by mass or more with respect to all the repeating units of the specific copolymer. The upper limit value of the content of the repeating unit derived from General Formula (Y1) is, for example, 95% by mass or less, preferably 80% by mass or less, and more preferably 75% by mass or less, with respect to all the repeating units of the specific copolymer.
<Other Copolymerization Components>
The specific copolymer may further contain a repeating unit derived from other copolymerizable monomers, in addition to the repeating unit containing a group represented by General Formula (X1) and the repeating unit derived from a monomer represented by General Formula (Y1).
The other copolymerizable monomers are not particularly limited, and examples thereof include monomers such as BLEMMER E, BLEMMER PE90, BLEMMER PE200, BLEMMER PE350, BLEMMER AE90, BLEMMER AE200, BLEMMER AE400, BLEMMER P, BLEMMER PP1000, BLEMMER PP500, BLEMMER PP800, BLEMMER AP400, BLEMMER AP550, BLEMMER AP800, BLEMMER BMA, BLEMMER CHMA, BLEMMER CHA, BLEMMER LMA, BLEMMER GLM, AND BLEMMER LA (all of which are manufactured by NOF Corporation), and monomers such as acrylic acid, 4-acryloylmorpholine, N,N-diisopropylacrylamide, vinylpyrrolidone, hydroxyethyl methacrylate, and acetoacetoxyethyl methacrylate.
In a case where the specific copolymer contains a repeating unit derived from other copolymerizable monomers, the content of the repeating unit derived from other copolymerizable monomers (in a case where there are a plurality of repeating units derived from other copolymerizable monomers, the total content of the plurality of repeating units) is, for example, 40% by mass or less, preferably 20% by mass or less, and more preferably 10% by mass or less, with respect to all the repeating units of the specific copolymer.
In the specific copolymer, the content of the repeating unit derived from a monomer containing two or more polymerizable groups is preferably less than 5 mol % with respect to all the repeating units of the specific copolymer, from the viewpoint that the mesogen moiety in General Formula (Y1) is easily movable and the diffuse reflectivity of the reflective layer is more excellent. Here, the polymerizable group may be, for example, a polymerizable ethylenically unsaturated group or a ring polymerizable group. Specific examples of the polymerizable group include a (meth)acryloyl group, a vinyl group, a styryl group, an allyl group, an epoxy group, and an oxetane group.
It is preferable that General Formula (Y1) does not include two or more polymerizable groups.
The weight-average molecular weight of the specific copolymer is less than 10,000. The weight-average molecular weight of the specific copolymer is more preferably less than 9,000 from the viewpoint of more excellent planarity. The lower limit of the weight-average molecular weight of the specific copolymer is not particularly limited, but is, for example, 4,000 or more. The dispersity (Mw/Mn) is usually 1.0 to 3.0, preferably 1.0 to 2.0, and more preferably 1.1 to 2.0.
The specific copolymer can be synthesized by a conventional method.
The specific copolymer may be used alone or in combination of two or more thereof.
The content of the specific copolymer (in a case where there are a plurality of specific copolymers, the total content of the plurality of specific copolymers) in the liquid crystal composition is preferably 0.01% by mass or more and less than 5% by mass, more preferably 0.01% to 3% by mass, and still more preferably 0.05% to 3% by mass with respect to the content of the polymerizable liquid crystal compound contained in the composition.
The liquid crystal composition contains a polymerizable liquid crystal compound. In addition, the polymerizable liquid crystal compound is intended to refer to a liquid crystal compound having a polymerizable group. Hereinafter, the polymerizable liquid crystal compound that can be used in the present invention will be described in detail.
The type of the liquid crystal compound is not particularly limited.
Generally, liquid crystal compounds can be classified into a rod type (rod-like liquid crystal compound) and a disc type (discotic liquid crystal compound, disk-like liquid crystal compound) depending on the shape thereof. Further, the rod type and the disk type each have a low molecular weight type and a high molecular weight type. The high molecular weight generally refers to having a degree of polymerization of 100 or more (Polymer Physics-Phase Transition Dynamics, Masao Doi, page 2, Iwanami Shoten, 1992). Any liquid crystal compound can be used in the present invention. Two or more liquid crystal compounds may be used in combination.
The liquid crystal compound has a polymerizable group. The type of the polymerizable group is not particularly limited, and a functional group capable of addition polymerization reaction is preferable, and a polymerizable ethylenically unsaturated group or a cyclic polymerizable group is more preferable. More specifically, the polymerizable group is preferably a (meth)acryloyl group, a vinyl group, a styryl group, an allyl group, an epoxy group, or an oxetane group, and more preferably a (meth)acryloyl group.
The number of polymerizable groups is not particularly limited, and may be one or more. Above all, the number of the polymerizable groups is preferably plural, more preferably 2 to 6, and still more preferably 2 to 4 from the viewpoint that the diffuse reflectivity of the reflective layer is more excellent.
The molecular weight of the liquid crystal compound is not particularly limited, but is preferably 400 or more and more preferably 700 or more. The upper limit of the molecular weight of the liquid crystal compound is not particularly limited, but is often 2000 or less (especially in a case of a low-molecular weight type liquid crystal compound).
In addition, in a case where a rod-like liquid crystal compound is used, the liquid crystal compound is preferably a compound having four or more rings in the core portion of the mesogen group in the liquid crystal compound, and more preferably a compound having five or more rings in the core portion of the mesogen group in the liquid crystal compound, from the viewpoint of controlling the viscosity.
The liquid crystal compound is preferably a liquid crystal compound represented by Formula (I) from the viewpoint that the reflective layer has more excellent diffuse reflectivity.
In the formula,
A represents a phenylene group which may have a substituent or a trans-1,4-cyclohexylene group which may have a substituent,
L represents a single bond or a linking group selected from the group consisting of —CH2O—, —OCH2—, —(CH2)2O—CO—, —CO—O(CH2)2—, —CO—O—, —O—CO—, —O—CO—O—, —CH═CH—CO—O—, —O—CO—CH═CH—, —CH═N—N═CH—, —C═N—, —N═C—, —C≡C—, and —NH—,
m represents an integer of 3 to 12,
Sp1 and Sp2 each independently represent a single bond or a linking group selected from the group consisting of a linear or branched alkylene group having 1 to 20 carbon atoms and a group where one or two or more —CH2— in a linear or branched alkylene group having 1 to 20 carbon atoms is substituted by —O—, —S—, —NH—, —N(CH3)—, —CO—, —O—CO—, or —CO—O—, and
Q1 and Q2 each independently represent a hydrogen atom or a polymerizable group selected from the group consisting of groups represented by Formulae (Q-1) to (Q-5), provided that one of Q1 and Q2 represents a polymerizable group.
A is a phenylene group which may have a substituent or a trans-1,4-cyclohexylene group which may have a substituent. In the present specification, the phenylene group is preferably a 1,4-phenylene group.
m pieces of A's may be the same as or different from each other.
In a case where a trans-1,4-cyclohexylene group which may have a substituent is contained as A, from the viewpoint of more excellent diffuse reflectivity of the reflective layer, upon assuming that the number obtained by dividing the number of trans-1,4-cyclohexylene groups which may have a substituent, which is represented by A, by m is defined as mc, a liquid crystal compound satisfying mc>0.1 is preferable, and a liquid crystal compound satisfying 0.4≤mc≤0.8 is more preferable.
Note that mc is a number represented by the following calculating expression.
mc=(the number of trans-1,4-cyclohexylene groups which may have a substituent represented by A)/m
m represents an integer of 3 to 12, preferably an integer of 3 to 9, more preferably an integer of 3 to 7, and still more preferably an integer of 3 to 5.
The substituent which the phenylene group and the trans-1,4-cyclohexylene group in Formula (I) may have is not particularly limited, and examples thereof include substituents selected from the group consisting of an alkyl group, a cycloalkyl group, an alkoxy group, an alkyl ether group, an amide group, an amino group, a halogen atom, and a group formed by combining two or more of these substituents. Examples of the substituent include substituents represented by —CO—X3-Sp3-Q3 which will be described later. The phenylene group and the trans-1,4-cyclohexylene group may have 1 to 4 substituents. In a case of having two or more substituents, the two or more substituents may be the same as or different from each other.
In the present specification, the alkyl group may be either linear or branched. The number of carbon atoms in the alkyl group is preferably 1 to 30, more preferably 1 to 10, and still more preferably 1 to 6. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, a 1,1-dimethylpropyl group, an n-hexyl group, an isohexyl group, a heptyl group, an octyl group, a nonyl group, a decyl group, an undecyl group, and a dodecyl group. The explanation of the alkyl group in the alkoxy group is also the same as the explanation on the foregoing alkyl group. Further, in the present specification, specific examples of the alkylene group in a case of being referred to as an alkylene group include divalent groups obtained by removing one hydrogen atom from each of the foregoing examples of the alkyl group. Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
In the present specification, the number of carbon atoms in the cycloalkyl group is preferably 3 or more and more preferably 5 or more and is preferably 20 or less, more preferably 10 or less, still more preferably 8 or less, and particularly preferably 6 or less. Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, and a cyclooctyl group.
The substituent which the phenylene group and the trans-1,4-cyclohexylene group may have is preferably a substituent selected from the group consisting of an alkyl group, an alkoxy group, and —CO—X3-Sp3-Q3. Here, X3 represents a single bond, —O—, —S—, or —N(Sp4-Q4)- or represents a nitrogen atom forming a ring structure together with Q3 and Sp3. Sp3 and Sp4 each independently represent a single bond or a linking group selected from the group consisting of a linear or branched alkylene group having 1 to 20 carbon atoms and a group where one or two or more —CH2— in a linear or branched alkylene group having 1 to 20 carbon atoms is substituted with —O—, —S—, —NH—, —N(CH3)—, —CO—, —O—CO—, or —CO—O—.
Q3 and Q4 each independently represent a hydrogen atom, a cycloalkyl group, a group where one or two or more —CH2— in a cycloalkyl group is substituted with —O—, —S—, —NH—, —N(CH3)—, —CO—, —O—CO—, or —CO—O—, or any polymerizable group selected from the group consisting of groups represented by Formulae (Q-1) to (Q-5).
Specific examples of the group where one or two or more —CH2— in a cycloalkyl group is substituted with —O—, —S—, —NH—, —N(CH3)—, —CO—, —O—CO—, or —CO—O— include a tetrahydrofuranyl group, a pyrrolidinyl group, an imidazolidinyl group, a pyrazolidinyl group, a piperidyl group, a piperazinyl group, and a morpholinyl group. Among them, a tetrahydrofuranyl group is preferable, and a 2-tetrahydrofuranyl group is more preferable.
In Formula (I), L represents a single bond or a linking group selected from the group consisting of —CH2O—, —OCH2—, —(CH2)2O—CO—, —CO—O(CH2)2—, —CO—O—, —O—CO—, —O—CO—O—, —CH═CH—CO—O—, —O—CO—CH═CH—, —CH═N—N═CH—, —C═N—, —N═C, —C≡C—, and —NH—. L is preferably —CO—O—, —O—CO—, or —NH—,
m pieces of L's may be the same as or different from each other.
Sp1 and Sp2 each independently represent a single bond or a linking group selected from the group consisting of a linear or branched alkylene group having 1 to 20 carbon atoms and a group where one or two or more —CH2— in a linear or branched alkylene group having 1 to 20 carbon atoms is substituted with —O—, —S—, —NH—, —N(CH3)—, —CO—, —O—CO—, or —CO—O—, Sp1 and Sp2 are each independently preferably a linking group formed by combining one or two or more groups selected from the group consisting of a linear alkylene group having 1 to 10 carbon atoms to which a linking group selected from the group consisting of —O—, —O—CO—, and —CO—O— is bonded to both terminals thereof, —O—CO—, —CO—O—, —O—, and a linear alkylene group having 1 to 10 carbon atoms, and more preferably a linear alkylene group having 1 to 10 carbon atoms to which —O— is bonded to both terminals thereof.
Q1 and Q2 each independently represent a hydrogen atom or a polymerizable group selected from the group consisting of groups represented by Formulae (Q-1) to (Q-5), provided that either one of Q1 and Q2 represents a polymerizable group.
The polymerizable group is preferably an acryloyl group (Formula (Q-1)) or a methacryloyl group (Formula (Q-2)).
Specific examples of the liquid crystal compound include a liquid crystal compound represented by Formula (1-11), a liquid crystal compound represented by Formula (I-21), and a liquid crystal compound represented by Formula (I-31). In addition to the foregoing compounds, known compounds such as a compound represented by Formula (I) in JP2013-112631A, a compound represented by Formula (I) in JP2010-070543A, a compound represented by Formula (I) in JP2008-291218A, a compound represented by Formula (I) in JP4725516B, a compound represented by General Formula (II) in JP2013-087109A, a compound described in paragraph [0043] of JP2007-176927A, a compound represented by Formula (1-1) in JP2009-286885A, a compound represented by General Formula (I) in WO2014/010325A, a compound represented by Formula (1) in JP2016-081035A, and a compound represented by Formulae (2-1) and (2-2) in JP2016-121339A can be mentioned.
In the formula, R11 represents a hydrogen atom, a linear or branched alkyl group having 1 to 12 carbon atoms, or —Z12-Sp12-Q12,
L11 represents a single bond, —CO—O—, or —CO—,
L12 represents —CO—O—, —O—CO—, —CO—NR2—, or —NR2—CO—,
R2 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms,
Z11 and Z12 each independently represent a single bond, —O—, —NH—, —N(CH3)—, —S—, —CO—O—, —O—CO—, —O—CO—O—, —CO—NR12, or —NR12—CO—,
Sp11 and Sp12 each independently represent a single bond, a linear or branched alkylene group having 1 to 12 carbon atoms which may be substituted with Q11, or a linking group obtained by substituting one or more —CH2— in a linear or branched alkylene group having 1 to 12 carbon atoms which may be substituted with Q11 with —O—, —S—, —NH—, —N(Q11)-, or —CO—,
Q11 represents a hydrogen atom, a cycloalkyl group, a group where one or two or more —CH2— in a cycloalkyl group are substituted with —O—, —S—, —NH—, —N(CH3)—, —CO—, —O—CO—, or —CO—O—, or a polymerizable group selected from the group consisting of groups represented by Formulae (Q-1) to (Q-5),
Q12 represents a hydrogen atom or a polymerizable group selected from the group consisting of groups represented by Formulae (Q-1) to (Q-5),
l11 represents an integer of 0 to 2,
m11 represents an integer of 1 or 2,
n11 represents an integer of 1 to 3, and
a plurality of R11's, a plurality of L11's, a plurality of L12's, a plurality of l11's, a plurality of Z11's, a plurality of Sp11's, and a plurality of Q11's may be respectively the same as or different from each other.
The liquid crystal compound represented by Formula (I-11) contains at least one -Z12-Sp12-Q12 in which Q12 is a polymerizable group selected from the group consisting of groups represented by Formulae (Q-1) to (Q-5), as R11.
In addition, in the liquid crystal compound represented by Formula (I-11), R11 is preferably -Z11-Sp11-Q11 in which Z11 is —CO—O—, —O—CO—, —CO—NR12—, or NR12—CO—, and Q11 is a polymerizable group selected from the group consisting of groups represented by Formulae (Q-1) to (Q-5). In addition, in the liquid crystal compound represented by Formula (I-11), R11 is preferably -Z12-Sp12-Q12 in which Z11 is —CO—O—, —CO—NR12—, or NR12—CO—, and Q12 is a polymerizable group selected from the group consisting of groups represented by Formulae (Q-1) to (Q-5).
All 1,4-cyclohexylene groups contained in the liquid crystal compound represented by Formula (I-11) are trans-1,4-cyclohexylene groups.
A suitable aspect of the liquid crystal compound represented by Formula (I-11) may be, for example, a compound in which L11 is a single bond, l11 is 1-(dicyclohexyl group), and Q11 is a polymerizable group selected from the group consisting of groups represented by Formulae (Q-1) to (Q-5).
Another suitable aspect of the liquid crystal compound represented by Formula (I-11) may be, for example, a compound in which m11 is 2, l11 is 0, and two R11's each represent -Z11-Sp12-Q12, and Q12 is a polymerizable group selected from the group consisting of groups represented by Formulae (Q-1) to (Q-5).
In the formula, Z21 and Z22 each independently represent a trans-1,4-cyclohexylene group which may have a substituent or a phenylene group which may have a substituent,
the above substituents are each independently 1 to 4 substituents selected from the group consisting of —CO—X21-Sp23-Q23, an alkyl group, and an alkoxy group,
m21 represents an integer of 1 or 2, and n21 represents an integer of 0 or 1,
in a case where m21 represents 2, n21 represents 0,
in a case where m21 represents 2, two Z21's may be the same or different,
at least one of Z21 or Z22 is a phenylene group which may have a substituent,
L21, L22, L23, and L24 each independently represent a single bond or a linking group selected from the group consisting of —CH2O—, —OCH2—, —(CH2)2—O—CO—, —CO—, —CO—O(CH2)2—, —CO—O—, —O—CO—, —O—CO—O—, —CH═CH—CO—O—, and —O—CO—CH═CH—,
X21 represents —O—, —S—, or —N(Sp25-Q25)- represents a nitrogen atom forming a ring structure together with Q23 and Sp23,
r21 represents an integer of 1 to 4,
Sp21, Sp21, Sp23, and Sp25 each independently represent a single bond or a linking group selected from the group consisting of a linear or branched alkylene group having 1 to 20 carbon atoms and a group where one or two or more —CH2— in a linear or branched alkylene group having 1 to 20 carbon atoms is substituted with —O—, —S—, —NH—, —N(CH3)—, —CO—, —O—CO—, or —CO—O—,
Q21 and Q22 each independently represent a polymerizable group selected from the group consisting of groups represented by Formulae (Q-1) to (Q-5),
Q23 represents a hydrogen atom, a cycloalkyl group, a group where one or two or more —CH2— in a cycloalkyl group is substituted with —O—, —S—, —NH—, —N(CH3)—, —CO—, —O—CO—, or —CO—O—, any one polymerizable group selected from the group consisting of groups represented by Formulae (Q-1) to (Q-5), or a single bond in a case where X21 is a nitrogen atom forming a ring structure together with Q23 and Sp23, and
Q25 represents a hydrogen atom, a cycloalkyl group, a group where one or two or more —CH2— in a cycloalkyl group is substituted with —O—, —S—, —NH—, —N(CH3)⇒, —O—CO—, or —CO—O—, or any one polymerizable group selected from the group consisting of groups represented by Formulae (Q-1) to (Q-5), provided that in a case where Sp25 is a single bond, Q25 is not a hydrogen atom.
It is also preferred that the liquid crystal compound represented by Formula (I-21) has a structure in which a 1,4-phenylene group and a trans-1,4-cyclohexylene group are alternately present. For example, preferred is a structure in which m21 is 2, n21 is 0, and Z21 is a trans-1,4-cyclohexylene group which may have a substituent or an arylene group which may have a substituent, each of which from the Q21 side, or a structure in which m21 is 1, n21 is 1, Z21 is an arylene group which may have a substituent, and Z22 is an arylene group which may have a substituent.
In the formula, R31 and R32 each independently represent an alkyl group, an alkoxy group, and a group selected from the group consisting of —CO—X31-Sp33,
n31 and n32 each independently represent an integer of 0 to 4,
X31 represents a single bond, —O—, —S—, or —N(Sp34-Q34)- or represents a nitrogen atom forming a ring structure together with Q33 and Sp33,
Z31 represents a phenylene group which may have a substituent,
Z32 represents a trans-1,4-cyclohexylene group which may have a substituent or a phenylene group which may have a substituent,
the above substituents are each independently 1 to 4 substituents selected from the group consisting of an alkyl group, an alkoxy group, and —CO—X31-Sp33-Q33,
m31 represents an integer of 1 or 2, and m32 represents an integer of 0 to 2,
in a case where m31 and m32 represent 2, two Z31's and Z32's may be the same or different,
L31 and L32 each independently represent a single bond or a linking group selected from the group consisting of —CH2O—, —OCH2—, —(CH2)2—CO—, —CO—O(CH2)2—, —CO—O—, —O—CO—, —O—CO—O—, —CH═CH—CO—O—, and —O—CO—CH═CH—,
Sp31, Sp32, Sp33, and Sp34 each independently represent a single bond or a linking group selected from the group consisting of a linear or branched alkylene group having 1 to 20 carbon atoms and a group where one or two or more —CH2— in a linear or branched alkylene group having 1 to 20 carbon atoms is substituted with —O—, —S—, —NH—, —N(CH3)—, —CO—, —O—CO—, or —CO—O—,
Q31 and Q32 each independently represent a polymerizable group selected from the group consisting of groups represented by Formulae (Q-1) to (Q-5), and
Q33 and Q34 each independently represent a hydrogen atom, a cycloalkyl group, a group where one or two or more —CH2— in a cycloalkyl group is substituted with —O—, —S—, —NH—, —N(CH3)—, —CO—, —O—CO—, or —CO—O—, or any one polymerizable group selected from the group consisting of groups represented by Formulae (Q-1) to (Q-5), provided that Q33 may represent a single bond in a case of forming a ring structure together with X31 and Sp33, and Q34 is not a hydrogen atom in a case where Sp34 is a single bond.
As the liquid crystal compound represented by Formula (I-31), particularly preferable compounds include a compound in which Z32 is a phenylene group and a compound in which m32 is 0.
It is also preferred that the compound represented by Formula (I) has a partial structure represented by Formula (II).
In Formula (II), black circles indicate the bonding positions with other moieties of Formula (I). It is sufficient that the partial structure represented by Formula (II) is included as a part of the partial structure represented by Formula (III) in Formula (I).
In the formula, R1 and R2 are each independently a group selected from the group consisting of a hydrogen atom, an alkyl group, an alkoxy group, and a group represented by —CO—X3-Sp3-Q3. Here, X3 represents a single bond, —O—, —S—, or —N(Sp4-Q4)- or represents a nitrogen atom forming a ring structure together with Q3 and Sp3. X3 is preferably a single bond or —O—. R1 and R2 are preferably —CO—X3-Sp3-Q3. It is also preferred that R1 and R2 are the same. The bonding position of each of R1 and R2 to the phenylene group is not particularly limited.
Sp3 and Sp4 each independently represent a single bond or a linking group selected from the group consisting of a linear or branched alkylene group having 1 to 20 carbon atoms and a group where one or two or more —CH2— in a linear or branched alkylene group having 1 to 20 carbon atoms are substituted with —O—, —S—, —NH—, —N(CH3)—, —CO—, —O—CO—, or —CO—O—. Sp3 and Sp4 are each independently preferably a linear or branched alkylene group having 1 to 10 carbon atoms, more preferably a linear alkylene group having 1 to 5 carbon atoms, and still more preferably a linear chain alkylene group having 1 to 3 carbon atoms.
Q3 and Q4 each independently represent a hydrogen atom, a cycloalkyl group, a group where one or two or more —CH2— in a cycloalkyl group are substituted with —O—, —S—, —NH—, —N(CH3)—, —CO—, —O—CO—, or —CO—O—, or any one polymerizable group selected from the group consisting of groups represented by Formulae (Q-1) to (Q-5).
It is also preferred that the compound represented by Formula (I) has, for example, a structure represented by Formula (II-2).
In the formula, A1 and A2 each independently represent a phenylene group which may have a substituent or a trans-1,4-cyclohexylene group which may have a substituent, and the above substituents are each independently 1 to 4 substituents selected from the group consisting of an alkyl group, an alkoxy group, and —CO—X3-Sp3-Q3,
L1, L2, and L3 each independently represent a single bond or a linking group selected from the group consisting of —CH2O—, —OCH2—, —(CH2)2O—CO—, —CO—O(CH2)2—, —CO—O—, —O—CO—, —O—CO—O—, —CH═CH—CO—O—, and —O—CO—CH═CH—,
n1 and n2 each independently represent an integer of 0 to 9, and n1+n2 is 9 or less.
Each of Q1, Q2, Sp1, and Sp2 has the same definition as that of each group in Formula (I). Each of X3, Sp3, Q3, R1, and R2 has the same definition as that of each group in Formula (II).
Another suitable aspect of the liquid crystal compound includes a compound represented by Formula (IV).
In Formula (IV), A1 represents an alkylene group having 2 to 18 carbon atoms, in which one CH2 or two or more non-adjacent CH2's in the alkylene group may be substituted with —O—;
Z1 represents —CO—,—O—CO—, or a single bond;
Z2 represents —CO— or —CO—CH═CH—;
R1 represents a hydrogen atom or a methyl group;
R2 represents a hydrogen atom, a halogen atom, a linear alkyl group having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, a phenyl group which may have a substituent, a vinyl group, a formyl group, a nitro group, a cyano group, an acetyl group, an acetoxy group, an N-acetylamide group, an acryloylamino group, an N,N-dimethylamino group, a maleimide group, a methacryloylamino group, an allyloxy group, an allyloxycarbamoyl group, an N-alkyloxycarbamoyl group in which the alkyl group has 1 to 4 carbon atoms, an N-(2-methacryloyloxyethyl)carbamoyloxy group, an N-(2-acryloyloxyethyl)carbamoyloxy group, or a group represented by Formula (IV-2); and
L1, L2, L3, and L4 each independently represent an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkoxycarbonyl group having 2 to 5 carbon atoms, an acyl group having 2 to 4 carbon atoms, a halogen atom, or a hydrogen atom, and at least one of L1, L2, L3, or L4 represents a group other than a hydrogen atom.
-Z5-T-Sp-P Formula (IV-2)
In Formula (IV-2), P represents an acryloyl group, a methacryl group, or a hydrogen atom, and Z5 represents a single bond, —CO—O—, —O—CO—, —CO—NR1— (where R1 represents a hydrogen atom or a methyl group), —NR1—CO—, —CO—S—, or —S—CO—, T represents 1,4-phenylene, and Sp represents a divalent aliphatic group having 1 to 12 carbon atoms which may have a substituent, in which one CH2 or two or more non-adjacent CH2's in the aliphatic group may be substituted with —O—, —S—, —O—CO—, —CO—O—, or —O—CO—O—.
The compound represented by Formula (IV) is preferably a compound represented by Formula (V).
In Formula (V), n1 represents an integer of 3 to 6;
R11 represents a hydrogen atom or a methyl group;
R12 represents —CO— or —CO—CH═CH—; and
R12 represents a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, a phenyl group, an acryloylamino group, a methacryloylamino group, an allyloxy group, or a group represented by Formula (IV-3).
-Z51-T-Sp-P Formula (IV-3)
In Formula (IV-3), P represents an acryloyl group or a methacryl group;
Z51 represents —CO—O— or —O—CO—;
T represents 1,4-phenylene; and
Sp represents a divalent aliphatic group having 2 to 6 carbon atoms which may have a substituent, in which one CH2 or two or more non-adjacent CH2's in the aliphatic group may be substituted with —O—, —O—CO—, —CO—O—, or O(═O)OO—.
n1 represents an integer of 3 to 6 and is preferably 3 or 4.
Z12 represents —CO— or CO—CH═CH— and preferably represents —CO—.
R12 represents a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, a phenyl group, an acryloylamino group, a methacryloylamino group, an allyloxy group, or a group represented by Formula (IV-3), more preferably represents a methyl group, an ethyl group, a propyl group, a methoxy group, an ethoxy group, a phenyl group, an acryloylamino group, a methacryloylamino group, or a group represented by Formula (IV-3), and still more preferably represents a methyl group, an ethyl group, a methoxy group, an ethoxy group, a phenyl group, an acryloylamino group, a methacryloylamino group, or a group represented by Formula (IV-3).
Note that R is intended to refer to Me.
Specific examples of the compound represented by Formula (IV) include the compounds exemplified below.
Another suitable aspect of the liquid crystal compound includes a compound represented by Formula (VI).
In Formula (VI), Z3 represents —CO— or —CH═CH—CO—;
Z4 represents —CO— or —CO—CH═CH—;
R3 and R4 each independently represent a hydrogen atom, a halogen atom, a linear alkyl group having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, an aromatic group which may have a substituent, a cyclohexyl group, a vinyl group, a formyl group, a nitro group, a cyano group, an acetyl group, an acetoxy group, an acryloylamino group, an N,N-dimethylamino group, a maleimide group, a methacryloylamino group, an allyloxy group, an allyloxycarbamoyl group, an N-alkyloxycarbamoyl group in which the alkyl group has 1 to carbon atoms, an N-(2-methacryloyloxyethyl)carbamoyloxy group, an N-(2-acryloyloxyethyl)carbamoyloxy group, or a group represented by Formula (VI-2); and
L5, L6, L7, and L8 each independently represent an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkoxycarbonyl group having 2 to 5 carbon atoms, an acyl group having 2 to 4 carbon atoms, a halogen atom, or a hydrogen atom, and at least one of L5, L6, L7, or L8 represents a group other than a hydrogen atom.
-Z5-T-Sp-P Formula (VI-2)
In Formula (VI-2), P represents an acryloyl group, a methacryl group, or a hydrogen atom, and Z5 represents CO—O—, —O—CO—, —CO—NR1— (where R1 represents a hydrogen atom or a methyl group), —NR1—CO—, —CO—S—, or S—CO—, T represents 1,4-phenylene, and Sp represents a divalent aliphatic group having 1 to 12 carbon atoms which may have a substituent, in which one CH2 or two or more non-adjacent CH2's in the aliphatic group may be substituted with —O—, —S—, —O—CO—, —CO—O—, or —O—CO—O—.
The compound represented by Formula (VI) is preferably a compound represented by Formula (VII).
In Formula (VII), Z13 represents —CO— or —CO—CH═CH—;
Z14 represents —CO— or —CH═CH—CO—; and
R13 and R14 each independently represent a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, a phenyl group, an acryloylamino group, a methacryloylamino group, an allyloxy group, or a group represented by Formula (IV-3).
Z13 represents —CO— or —CO—CH═CH— and preferably represents —CO—.
R13 and R14 each independently represent a hydrogen atom, a linear alkyl group having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, a phenyl group, an acryloylamino group, a methacryloylamino group, an allyloxy group, or a group represented by Formula (IV-3), preferably represents a methyl group, an ethyl group, a propyl group, a methoxy group, an ethoxy group, a phenyl group, an acryloylamino group, a methacryloylamino group, or a group represented by Formula (IV-3), and more preferably represents a methyl group, an ethyl group, a methoxy group, an ethoxy group, a phenyl group, an acryloylamino group, a methacryloylamino group, or a group represented by Formula (IV-3).
Specific examples of the compound represented by Formula (VI) include the compounds exemplified below.
Another suitable aspect of the liquid crystal compound includes a compound represented by Formula (VIII).
In Formula (VIII), A2 and A3 each independently represent an alkylene group having 2 to 18 carbon atoms, and one CH2 or two or more non-adjacent CH2's in the alkylene group may be substituted with —O—;
Z5 represents —CO—, —O—CO—, or a single bond;
Z6 represents —CO—, —CO—O—, or a single bond;
R5 and R6 each independently represent a hydrogen atom or a methyl group; and
L9, L10, L11, and L12 each independently represent an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an alkoxycarbonyl group having 2 to 5 carbon atoms, an acyl group having 2 to 4 carbon atoms, a halogen atom, or a hydrogen atom, and at least one of L9, L10, L11, or L12, or L12 represents a group other than a hydrogen atom.
The compound represented by Formula (VIII) is preferably a compound represented by Formula (IX).
In Formula (IX), n2 and n3 each independently represent an integer of 3 to 6; and
R15 and R16 each independently represent a hydrogen atom or a methyl group.
In Formula (IX), it is preferred that n2 and n3 each independently represent an integer of 3 to 6, and n2 and n3 are 4.
In Formula (IX), it is preferred that R15 and R16 each independently represent a hydrogen atom or a methyl group, and R15 and R16 each represent a hydrogen atom.
Specific examples of the compound represented by Formula (VIII) include the compounds exemplified below.
The liquid crystal compound can be produced by a known method.
The content of the liquid crystal compound in the liquid crystal composition is preferably 50% by mass or more, more preferably 60% by mass or more, and still more preferably 60% to 95% by mass with respect to the total solid content of the composition.
The liquid crystal composition may contain a chiral agent.
The type of chiral agent (chiral compound) is not particularly limited. The chiral agent may be liquid crystalline or non-liquid crystalline. The chiral agent may be selected from a variety of known chiral agents (for example, as described in Liquid Crystal Device Handbook, Chap. 3, Item 4-3, Chiral Agents for Twisted Nematic (TN) and Super Twisted Nematic (STN), p. 199, edited by the 142nd Committee of the Japan Society for the Promotion of Science, 1989). The chiral agent generally contains an asymmetric carbon atom. However, an axial asymmetric compound or planar asymmetric compound not containing an asymmetric carbon atom may also be used as the chiral agent. Examples of the axial asymmetric compound or the planar asymmetric compound include binaphthyl, helicene, paracyclophane, and derivatives thereof. The chiral agent may have a polymerizable group.
The content of the chiral agent in the composition is preferably 0.5% to 30% by mass with respect to the total mass of the liquid crystal compound. The chiral agent is preferably used in a smaller amount, as it tends not to affect the liquid crystallinity. Accordingly, the chiral agent is preferably a compound having a strong twisting power in order that the compound could achieve twisted alignment of a desired helical pitch even in a case where the amount thereof used is small.
Examples of such a chiral agent having strong twisting power include the chiral agents described in, for example, JP2002-302487A, JP2002-080478A, JP2002-080851A, JP2002-179668A, JP2002-179670A, JP2002-338575A, JP2002-180051A, JP1987-081354A (JP-S62-081354A), WO2002/006195A, JP2011-241215A, JP2003-287623A, and JP2014-034581A, and LC-756 manufactured by BASF SE.
The liquid crystal composition may contain components other than the liquid crystal compound and the specific copolymer.
<Polymerization Initiator>
The liquid crystal composition may contain a polymerization initiator.
The polymerization initiator is preferably a photopolymerization initiator capable of initiating a polymerization reaction upon irradiation with ultraviolet rays. Examples of the photopolymerization initiator include α-carbonyl compounds (as described in U.S. Pat. Nos. 2,367,661A and 2,367,670A), acyloin ethers (as described in U.S. Pat. No. 2,448,828A), α-hydrocarbon-substituted aromatic acyloin compounds (as described in U.S. Pat. No. 2,722,512A), polynuclear quinone compounds (as described in U.S. Pat. Nos. 3,046,127A and 2,951,758A), combinations of triarylimidazole dimer and p-aminophenyl ketone (as described in U.S. Pat. No. 3,549,367A), acridine and phenazine compounds (as described in JP1985-105667A (JP-S60-105667A) and U.S. Pat. No. 4,239,850A), and oxadiazole compounds (as described in U.S. Pat. No. 4,212,970A).
The content of the polymerization initiator in the liquid crystal composition is not particularly limited, but it is preferably 0.1% to 20% by mass and more preferably 1% to 10% by mass, with respect to the total solid content of the liquid crystal compound.
<Other Additives>
The liquid crystal composition may contain one or two or more other additives such as an antioxidant, an ultraviolet absorber, a sensitizer, a stabilizer, a plasticizer, a chain transfer agent, a polymerization inhibitor, an antifoaming agent, a leveling agent, a thickener, a flame retardant, a surface-active substance, a dispersant, and a color material such as a dye and a pigment.
The liquid crystal composition may contain a thickener for the purpose of increasing the viscosity.
The thickener is preferably one capable of increasing the viscosity without significantly disturbing the alignment of the liquid crystal. For example, a polymer having a mesogenic structure is preferable.
Further, for example, a compound having a hydrogen bonding functional group is also preferable. The hydrogen bonding functional group is preferably a hydroxyl group, an amino group, a carboxyl group, a sulfo group, an amido group, a urethane group, a urea group, or the like.
The liquid crystal composition can be applied to various applications. Specifically, a cured product (for example, in the form of a film or the like) is obtained by subjecting the liquid crystal composition to a polymerization treatment (light irradiation treatment, heat treatment, or the like), and the cured product can be suitably applied, for example, as an optically anisotropic body and a reflective layer having excellent diffuse reflectivity. In addition, the optically anisotropic body is intended to refer to a substance which has optical anisotropy. In addition, the reflective layer corresponds to a layer formed by fixing a cholesteric liquid crystalline phase and can reflect light in a predetermined reflection band.
Hereinafter, a method for producing a reflective layer according to the embodiment of the present invention will be described.
The method for producing a reflective layer according to the embodiment of the present invention preferably has the following steps 1 to 3.
Step 1: a step of forming a composition layer using the above-mentioned liquid crystal composition on a transparent base material that has not been subjected to a uniaxial alignment treatment
Step 2: a step in which the liquid crystal compound contained in the composition layer obtained through the step 1 is aligned into a cholesteric liquid crystalline phase state.
Step 3: a step of fixing the cholesteric liquid crystalline phase after the step 2
In the step 1, first, the above-mentioned composition layer is prepared.
The method for producing the composition layer is not particularly limited and may be, for example, a method in which the liquid crystal composition is applied onto a base material to form a composition layer.
The base material is not particularly limited as long as it is not subjected to a uniaxial alignment treatment and supports the composition layer. With regard to the base material, more random alignment of the surface on which the composition layer is formed leads to more excellent diffuse reflectivity of a reflective layer to be formed.
The base material is particularly preferably a transparent base material. The transparent base material is intended to refer to a base material having a transmittance of visible light of 60% or more, and the transmittance thereof is preferably 80% or more and more preferably 90% or more. Note that the upper limit value of the transmittance is 100% or less.
The material constituting the base material is not particularly limited, and examples thereof include a cellulose-based polymer, a polycarbonate-based polymer, a polyester-based polymer, a (meth)acrylic polymer, a styrene-based polymer, a polyolefin-based polymer, a vinyl chloride-based polymer, an amide-based polymer, an imide-based polymer, a sulfone-based polymer, a polyether sulfone-based polymer, and a polyether ether ketone-based polymer. The base material is preferably a polymer obtained by curing a mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate, from the viewpoint that the diffuse reflectivity of the reflective layer is more excellent.
The base material may have a single-layer structure or a multilayer structure. In a case where the base material has a multilayer structure, the layer on the reflective layer side may be a layer that has not been subjected to a uniaxial alignment treatment.
The base material may contain various additives such as an ultraviolet (UV) absorber, a matting agent fine particle, a plasticizer, a deterioration inhibitor, and a release agent.
In addition, the base material preferably has low birefringence in the visible light region. For example, the phase difference at a wavelength of 550 nm of the base material is preferably 50 nm or less and more preferably 20 nm or less.
The thickness of the base material is not particularly limited, but it is preferably 10 to 200 μm and more preferably 20 to 100 μm from the viewpoint of thinning and handleability.
The thickness is intended to refer to an average thickness, and is obtained by measuring thicknesses at any five places of the base material and arithmetically averaging the measured values.
In a case where the above-mentioned composition is applied, the composition may contain a solvent, if necessary.
The solvent may be, for example, water or an organic solvent. Examples of the organic solvent include amides such as N,N-dimethylformamide; sulfoxides such as dimethylsulfoxide; heterocyclic compounds such as pyridine; hydrocarbons such as benzene and hexane; alkyl halides such as chloroform and dichloromethane; esters such as methyl acetate, butyl acetate, and propylene glycol monoethyl ether acetate; ketones such as acetone, 2-butanone, methyl ethyl ketone, cyclohexanone, and cyclopentanone; ethers such as tetrahydrofuran and 1,2-dimethoxyethane; and 1,4-butanediol diacetate. These solvents may be used alone or in combination of two or more thereof.
The method of applying the composition onto the base material is not particularly limited, and examples thereof include a wire bar coating method, an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, and a die-coating method.
If necessary, a treatment for drying the composition applied onto the base material may be carried out after application. By carrying out the drying treatment, the solvent can be removed from the applied composition.
The film thickness of the composition layer disposed on the base material is not particularly limited, but is preferably 0.1 to 20 μm, more preferably 0.2 to 15 μm, and still more preferably 0.5 to 10 μm from the viewpoint of more excellent diffuse reflectivity of the reflective layer.
The step 2 is a step in which the liquid crystal compound contained in the composition layer obtained through the step 1 is aligned into a cholesteric liquid crystalline phase state.
The method of aligning the liquid crystal compound may be, for example, a method of heating the composition layer. Specifically, the composition (composition layer) applied onto the substrate is heated to align the liquid crystal compound in the composition layer into a cholesteric liquid crystalline phase state.
The liquid crystalline phase transition temperature of the composition layer is preferably in the range of 10° C. to 250° C. and more preferably in the range of 10° C. to 150° C., from the viewpoint of manufacturing suitability.
As to preferred heating conditions, it is preferable to heat the composition layer at 40° C. to 100° C. (preferably 60° C. to 100° C.) for 0.5 to 5 minutes (preferably 0.5 to 2 minutes).
In a case of heating the composition layer, it is preferable not to heat the composition layer to a temperature at which the liquid crystal compound becomes an isotropic phase (Iso). In a case where the composition layer is heated above the temperature at which the liquid crystal compound becomes an isotropic phase, defects of the cholesteric liquid crystalline phase are increased, which is not preferable.
The step 3 corresponds to a step of fixing the cholesteric liquid crystalline phase, and is carried out after the step 2. That is, the reflective layer obtained through the step 3 corresponds to a layer formed by fixing the cholesteric liquid crystalline phase.
Here, as the state where the cholesteric liquid crystalline phase is “fixed”, the most typical and preferred aspect is a state in which the alignment of the liquid crystal compound brought into a cholesteric liquid crystalline phase is retained. The state where the liquid crystalline phase is “fixed” is not limited thereto, and specifically, it refers to a state in which, in a temperature range of usually 0° C. to 50° C. and in a temperature range of −30° C. to 70° C. under more severe conditions, the layer has no fluidity and can keep an fixed alignment state stably without causing changes in alignment state due to external field or external force. In the present invention, as will be described later, it is preferable to fix the alignment state of a cholesteric liquid crystalline phase by a curing reaction proceeding upon irradiation with ultraviolet rays.
In the layer obtained by fixing a cholesteric liquid crystalline phase, it is sufficient that the optical properties of the cholesteric liquid crystalline phase are retained in the layer, and finally the composition in the layer no longer needs to show liquid crystallinity.
The method of the fixing treatment is not particularly limited, and examples thereof include a photo curing treatment and a thermal curing treatment. Among them, a light irradiation treatment is preferable, and an ultraviolet irradiation treatment is more preferable. Such a fixing treatment is preferably a polymerization reaction upon light irradiation (particularly ultraviolet irradiation), and more preferably a radical polymerization reaction upon light irradiation (particularly ultraviolet irradiation).
For ultraviolet irradiation, a light source such as an ultraviolet lamp is used.
The irradiation energy quantity of ultraviolet rays is not particularly limited, but it is generally preferably about 0.1 to 0.8 J/cm2. The irradiation time of the ultraviolet rays is not particularly limited, but it may be determined as appropriate from the viewpoint of both sufficient strength and productivity of the obtained reflective layer.
The method for producing a reflective layer according to the embodiment of the present invention preferably includes a step 4, which is a step of cooling the composition layer in a cholesteric liquid crystalline phase state, between the step 2 and the step 3, from the viewpoint of further improving the diffuse reflectivity of the reflective layer. In particular, in a case where the liquid crystal composition contains a chiral agent whose helical twisting power (HTP) changes depending on the temperature, a reflective layer having more excellent diffuse reflectivity can be formed through the step 4.
In a case where the composition is cooled, it is preferable to cool the composition layer such that the temperature of the composition layer is lowered by 30° C. or more, from the viewpoint that the diffuse reflectivity of the reflective layer is more excellent. Above all, from the viewpoint that the above effect is more excellent, it is preferable to cool the composition layer so as to lower by 40° C. or more, and it is more preferable to cool the composition layer so as to lower by 50° C. or more. The upper limit value of the reduced temperature range of the cooling treatment is not particularly limited, but is usually about 70° C.
In other words, the above cooling treatment is intended to cool the composition layer so as to be T−30° C. or less in a case where the temperature of the composition layer in a cholesteric liquid crystalline phase state before cooling is T ° C.
The cooling method is not particularly limited, and includes a method in which a substrate on which the composition layer is disposed is allowed to stand in an atmosphere at a predetermined temperature.
In a case where the step 4 is carried out, it is preferable that the above-described fixing treatment in the step 3 is carried out simultaneously with the step 4 or after the step 4.
The reflective layer is a layer showing selective reflection properties with respect to light in a predetermined wavelength range. The reflective layer functions as a circularly polarized selective reflective layer that selectively reflects either the dextrorotatory circularly polarized light or the levorotatory circularly polarized light in the selective reflection wavelength range and transmits the other sense circularly polarized light. A film including one or two or more reflective layers can be used for various applications. In a film including two or more layers of a reflective layer, the senses of circularly polarized light reflected by the reflective layers may be the same or opposite to each other depending on the application. In addition, the center wavelengths of selective reflection of the reflective layers, which will be described later, may be the same as or different from each other depending on the application.
In the present specification, the term “sense” for circularly polarized light means dextrorotatory circularly polarized light or levorotatory circularly polarized light. The sense of circularly polarized light is defined such that, in a case where light is viewed as it proceeds toward an observer and in a case where the distal end of the electric field vector rotates clockwise as time increases, the sense is dextrorotatory circularly polarized light, and in a case where it rotates counterclockwise, the sense is levorotatory circularly polarized light. In the present specification, the term “sense” may be used for the twisted direction of the helix of the cholesteric liquid crystal. Selective reflection by the cholesteric liquid crystal reflects dextrorotatory circularly polarized light and transmits levorotatory circularly polarized light in a case where the twisted direction (sense) of the helix of the cholesteric liquid crystal is right-handed, whereas it reflects levorotatory circularly polarized light and transmits dextrorotatory circularly polarized light in a case where the sense is left-handed.
For example, a film including a reflective layer exhibiting selective reflection properties in the visible light wavelength range (wavelength of 400 to 750 nm) can be used as a screen for projected image display and a half mirror. Further, by controlling the reflection band, such a film can be used as a filter that improves the color purity of display light of a color filter or a display (for example, see JP2003-294948A).
In addition, the reflective layer can be used for various applications such as a polarizing element, a reflective film, an anti-reflection film, a viewing angle compensating film, holography, and an alignment film, which are constituent elements of an optical element.
Hereinafter, the application as a projected image display member which is a particularly preferable application will be described.
By the above-mentioned function of the reflective layer, a projected image can be formed by reflecting circularly polarized light of either sense at the wavelength showing selective reflection among the projected light. The projected image may be visually recognized as such by being displayed on the surface of the projected image display member or may be a virtual image which appears to float above the projected image display member as viewed from an observer.
The center wavelength λ of the selective reflection depends on the pitch P of the helical structure (=the period of the helix) in a cholesteric liquid crystalline phase and follows the relationship of λ=n×P with the average refractive index n of the reflective layer. Here, the center wavelength λ of the selective reflection of the reflective layer means a wavelength at the center position of the reflection peak of the circularly polarized reflection spectrum measured from the normal direction of the reflective layer. As can be seen from the above Expression, the center wavelength of the selective reflection can be adjusted by adjusting the pitch of the helical structure. That is, by adjusting the n value and the P value, for example, in order to selectively reflect either the dextrorotatory circularly polarized light or the levorotatory circularly polarized light with respect to the blue light, the center wavelength λ, is adjusted so that an apparent center wavelength of the selective reflection can be set to a wavelength range of 450 to 495 nm. Incidentally, the apparent center wavelength of the selective reflection means a wavelength at the center position of the reflection peak of the circularly polarized reflection spectrum of the reflective layer measured from the observation direction in practical use (in a case of being used as a projected image display member). Since the pitch of the cholesteric liquid crystalline phase depends on the type of the chiral agent to be used together with the liquid crystal compound or the addition concentration thereof, a desired pitch can be obtained by adjusting these factors. For the method of measuring the sense and pitch of helix, methods described in “Easy Steps in Liquid Crystal Chemistry Experiment” p 46, edited by The Japanese Liquid Crystal Society, Sigma Publishing, published in 2007, and “Liquid Crystal Handbook” p 196, Editorial Committee of Liquid Crystal Handbook, Maruzen can be used.
In addition, a projected image display member capable of displaying full color projected images can be produced by preparing and laminating reflective layers having an apparent center wavelength of the selective reflection in the red light wavelength range, the green light wavelength range, and the blue light wavelength range, respectively.
By adjusting the center wavelength of the selective reflection of each reflective layer according to the emission wavelength range of the light source used for projection and the mode of use of the projected image display member, a clear projected image can be displayed with high efficiency of light utilization. In particular, by adjusting the center wavelengths of the selective reflection of the reflective layer respectively according to the light emission wavelength range of the light source used for projection or the like, a clear color projected image can be displayed with high efficiency of light utilization.
In addition, for example, in a case where the projected image display member is configured to be transmissive to light in the visible light region, a half mirror that can be used as a combiner for a head-up display can be obtained. The projected image display half mirror can display the image projected from the projector in a visible manner, and in a case where the projected image display half mirror is observed from the same surface side where the image is displayed, can simultaneously observe the information or scenery on the opposite surface side.
The copolymer according to the embodiment of the present invention contains a repeating unit derived from the monomer represented by General Formula (X2) and a repeating unit derived from the monomer represented by General Formula (Y1), and has a weight-average molecular weight of less than 10,000. That is, the copolymer according to the embodiment of the present invention corresponds to one embodiment of the specific copolymer described above. The suitable aspect of the copolymer is the same as the suitable aspect of the specific copolymer described above, and therefore the description thereof will be omitted.
Hereinafter, the present invention will be described in more detail with reference to Examples. The materials, the used amount, the ratio, the contents of a treatment, and the procedures of a treatment described in Examples below may be suitably modified without departing from the spirit of the present invention. Accordingly, the scope of the present invention should not be limitatively interpreted by Examples described below.
Hereinafter, Synthesis Examples of copolymer 1-1 and copolymer 1-8 used in the Examples are shown as examples.
According to JP2013-067603A, monomer 1 was synthesized according to the following synthesis procedure. In addition, “MsCl” is intended to refer to methanesulfonyl chloride, and “TEA” is intended to refer to triethylamine.
84 g of cyclohexanone was charged into a 500 ml three-neck flask equipped with a stirrer, a thermometer, a reflux cooling pipe, and a nitrogen gas inlet, the inside of the flask was sufficiently purged with nitrogen, and then the temperature was raised to an internal temperature of 80° C.
Then, a mixed solution of 13.8 g (32.9 mmol) of 2-(perfluorohexyl)ethyl acrylate, 23.8 g (48.6 mmol) of monomer 1, 209 g of cyclohexanone, and 0.68 g of an azo polymerization initiator (V-601, manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise into the flask at a constant speed such that the dropwise addition was completed in 180 minutes. After the completion of the dropwise addition, the obtained reaction solution was further stirred at 80° C. for 2 hours, and then 0.07 g of an azo polymerization initiator (V-601, manufactured by Wako Pure Chemical Industries, Ltd.) was added thereto. Thereafter, the temperature of the reaction solution was raised to 90° C., and stirring was further continued for 2 hours to obtain copolymer 1-1 represented by the following formula.
The weight-average molecular weight (Mw) of the copolymer 1-1 was 5,800 (calculated in terms of polystyrene by gel permeation chromatography (GPC), in which the columns used were TSKgel SuperHZM-H, TSKgel SuperHZ4000, and TSKgel SuperHZ200 (manufactured by Tosoh Corporation)).
The compositional ratio of each repeating unit in the copolymer 1-1 is based on “% by mass”. The compositional ratio of each repeating unit in the copolymer 1-2 to copolymer 1-10 and alignment control agent X-1 to alignment control agent X-4 is also based on “% by mass”.
According to Synthesis Example of monomer 1, monomer 2 was synthesized according to the following synthesis procedure.
8.5 g (20.3 mmol) of 2-(perfluorohexyl)ethyl acrylate, 19.7 g (33.7 mmol) of monomer 2, and 135 g of cyclohexanone were charged into a 300 ml three-neck flask equipped with a stirrer, a thermometer, a reflux cooling pipe, and a nitrogen gas inlet, the inside of the flask was sufficiently purged with nitrogen, and then the temperature was raised to an internal temperature of 80° C.
Next, a mixed solution of 1.0 g of an azo polymerization initiator (V-601, manufactured by Wako Pure Chemical Industries, Ltd.) and 31.3 g of cyclohexanone was added dropwise into the flask at a constant speed such that the dropwise addition was completed in 210 minutes. After the completion of the dropwise addition, the obtained reaction solution was stirred at 80° C. for 2 hours, then heated to 90° C., and further stirred for 2 hours to obtain copolymer 1-8 represented by the following formula.
The weight-average molecular weight (Mw) of the copolymer 1-8 was 8,800 (calculated in terms of polystyrene by gel permeation chromatography (GPC), in which the columns used were TSKgel SuperHZM-H, TSKgel SuperHZ4000, and TSKgel SuperHZ200 (manufactured by Tosoh Corporation)).
The components shown in Table 1 below were mixed to prepare liquid crystal compositions of Examples 1 to 12 (corresponding to liquid crystal compositions 1 to 12) and liquid crystal compositions 1 to 5 of Comparative Examples (corresponding to liquid crystal compositions 13 to 17). Table 1 is shown below.
The various components shown in Table 1 are shown below.
The copolymer 1-1 to copolymer 1-10 shown in Table 1 are shown below.
The rod-like liquid crystal compound 201 shown in Table 1 is shown below.
The rod-like liquid crystal compound 202 shown in Table 1 is shown below.
The rod-like liquid crystal compound 203 shown in Table 1 is shown below.
The chiral agent A shown in Table 1 is shown below.
Note that the chiral agent A is a chiral agent whose helical twisting power (HTP) changes depending on the temperature, and in a case of comparing the absolute value of HTP at 95° C. with the absolute value of HTP at 30° C., the absolute value of HTP at 30° C. is larger.
The alignment control agent X-1 shown in Table 1 is shown below. A compound synthesized according to JP2006-016599A was used as the alignment control agent X-1.
The alignment control agent X-2 shown in Table 1 is shown below.
The alignment control agent X-3 shown in Table 1 is shown below.
The alignment control agent X-4 shown in Table 1 is shown below. A compound synthesized according to JP2007-217656A was used as the alignment control agent X-4.
The following components were mixed to prepare a polymerizable composition coating liquid A.
The polymerizable composition coating liquid A was applied onto a PET (polyethylene terephthalate) film (manufactured by Toyobo Co., Ltd.) at room temperature using a wire bar. The obtained coating layer was dried at room temperature for 30 seconds, and then heated in an atmosphere at 85° C. for 2 minutes.
Thereafter, the coating film was irradiated with ultraviolet rays at 30° C. for 6 seconds using a D bulb (lamp 90 mW/cm2, output 60%, manufactured by Fusion Co., Ltd.) to form an acrylic layer A having a thickness of 2 μm (corresponding to a base material not subjected to uniaxial alignment).
The thickness of the acrylic layer A was measured by the following method.
<Film Thickness Measurement>
A part of the formed acrylic layer A was peeled off, and the film thickness was measured with a 10× objective lens using a profile measurement laser microscope VK-X200 (manufactured by Keyence Corporation).
The liquid crystal composition shown in Table 1 was applied onto the prepared acrylic layer A using a wire bar to form a composition layer. Next, the composition layer of the liquid crystal composition was dried at room temperature for 50 seconds, and then heated in an atmosphere at 95° C. for 1 minute to align the liquid crystal compound (in other words, being brought into a cholesteric liquid crystalline phase state). Next, the composition layer in which the liquid crystal compound was aligned was cooled to 30° C.
Thereafter, with respect to the composition layer in which the liquid crystal compound was aligned, the coating layer was irradiated with ultraviolet rays at 30° C. for 8 seconds using a D bulb (lamp 90 mW/cm2, output 80%, manufactured by Fusion Co., Ltd.) to form a reflective layer (fixed cholesteric liquid crystal layer) having a thickness of 1.6 μm. The thickness of the reflective layer was measured by a method which will be described later.
It was confirmed that each of the reflective layers had a reflection peak in a wavelength range of 450 to 650 nm.
In addition, the cross-sectional SEM observation of the reflective layer confirmed that the reflective layer of the Examples gives a stripe pattern of a bright portion (continuous line) and a dark portion (continuous line) to have a region in which the angle between the normal of a line formed by at least one dark portion and the surface of the CL layer periodically or irregularly changes.
A part of the formed reflective layer was peeled off, and the film thickness was measured with a 10× objective lens using a profile measurement laser microscope VK-X200 (manufactured by Keyence Corporation).
<Evaluation of Diffuse Reflectivity (reflection amount at 45° (“45° reflection amount”))>
In addition, the prepared reflective layer was set facing the light source side on a spectrophotometer V-670 (manufactured by JASCO Corporation) equipped with an absolute reflectance measurement system, and the degree of the reflection performance at 45° was evaluated under the conditions of 0° incidence and 45° detection.
In addition, for the evaluation of the reflection performance at 45°, a graph was plotted by taking the wavelength on the lateral axis and the reflectance on the vertical axis, the reflectance derived from the substrate was removed, the area of the reflection peak in a region of 450 to 650 nm corresponding to the selective reflection wavelength of the reflective layer was calculated, and the size of this area was evaluated as the reflection amount at 45°.
The reflection amount is preferably 5.0 or more and more preferably 7.0 or more.
The results are shown in Table 2.
<Planar Evaluation>
With respect to the composition layer immediately after application using a wire bar, the surface state was visually confirmed under crossed nicols, and the planarity was evaluated according to the following evaluation standards.
In addition, in a case where the evaluation result was “C” or higher, it was judged as pass. The evaluation result is preferably “B” or higher and more preferably “A”, from the viewpoint of more excellent production efficiency. The results are shown in Table 2.
(Evaluation Standards)
“A”: “Drying unevenness” and “foreign matter” are not observed.
“B”: “Drying unevenness” or “foreign matter” is slightly observed, but it can be used without any problem.
“C”: “Unevenness due to drying unevenness” or “foreign matter” is slightly observed, but it can be used without any problem.
“D”: “Unevenness due to drying unevenness” or “foreign matter” is often observed, which is thus not suitable for use.
In the following table, “Content of repeating unit represented by General Formula (X1)” is intended to refer to the content (% by mass) of the repeating unit containing a group represented by General Formula (X1) with respect to all the repeating units of the specific copolymer.
In the table, “-” shown in the column of “Whether or not Z1 in General Formula (Y1) is hydrogen atom” is intended to mean that the copolymer used does not contain the “repeating unit represented by General Formula (Y1)”.
In the table, “-” shown in the column of “Content of repeating unit represented by General Formula (X1)” is intended to mean that the copolymer used does not contain the “repeating unit represented by General Formula (X1)”.
From the results in Table 2, it was clear that the liquid crystal compositions of Examples had excellent planarity in a case of being formed into a coating film and was also capable of forming a reflective layer having excellent diffuse reflectivity.
From the comparison between Example 1 and Example 2 and the comparison between Example 3 and Example 4, it was confirmed that the diffuse reflectivity of the reflective layer was more excellent by carrying out a step of cooling the composition layer in a cholesteric liquid crystalline state (corresponding to the step 4) using a temperature-dependent chiral agent.
From the results of Example 7, it was confirmed that the planarity of the coating film was further improved in a case where the weight-average molecular weight of the specific copolymer was less than 9,000.
From the results of Example 8, it was confirmed that the planarity of the coating film was further improved and the reflective layer was more excellent in diffuse reflectivity, in a case where the content of the repeating unit containing a group represented by General Formula (X1) in the specific copolymer was 25% by mass or more with respect to all the repeating units.
From the results of Example 9, it was confirmed that, in the repeating unit represented by General Formula (Y1) in the specific copolymer, in a case where Z1 is not a hydrogen atom (in a case where Z1 is preferably an alkyl group having 1 to 20 carbon atoms in which —CH2— may be substituted with —O—, —CO—O—, —O—CO—, or —CO—O—, —O—CO—, or —CO—, an alkenyl group having 2 to 20 carbon atoms in which —CH2— may be substituted with —O— or —CO—, a halogen atom, a cyano group, an acetyl group, a formyl group, a carboxy group, or a hydroxy group), the horizontal alignment of the liquid crystal compound was suppressed and the reflective layer was more excellent in diffuse reflectivity.
| Number | Date | Country | Kind |
|---|---|---|---|
| JP2017-192714 | Oct 2017 | JP | national |
This application is a Continuation of PCT International Application No. PCT/JP2018/036854 filed on Oct. 2, 2018, which claims priority under 35 U.S.C. § 119(a) to Japanese Patent Application No. 2017-192714 filed on Oct. 2, 2017, The above application is hereby expressly incorporated by reference, in its entirety, into the present application.
| Number | Name | Date | Kind |
|---|---|---|---|
| 20050045854 | Radcliffe | Mar 2005 | A1 |
| 20130203920 | Tanabe | Aug 2013 | A1 |
| 20160108316 | Kurisawa et al. | Apr 2016 | A1 |
| 20160272888 | Endou et al. | Sep 2016 | A1 |
| 20170299785 | Saitoh | Oct 2017 | A1 |
| 20180142155 | Kurisawa et al. | May 2018 | A1 |
| Number | Date | Country |
|---|---|---|
| 2003-121853 | Apr 2003 | JP |
| 2003121853 | Apr 2003 | JP |
| 2006-16599 | Jan 2006 | JP |
| 2007-504296 | Mar 2007 | JP |
| 2013-71945 | Apr 2013 | JP |
| 2014-215360 | Nov 2014 | JP |
| 2017-122241 | Jul 2017 | JP |
| WO 2014123056 | Aug 2014 | WO |
| WO 2015076031 | May 2015 | WO |
| WO-2016111341 | Jul 2016 | WO |
| WO 2016204066 | Dec 2016 | WO |
| WO 2017010560 | Jan 2017 | WO |
| WO-2017010560 | Jan 2017 | WO |
| Entry |
|---|
| Machine Translation of JP2003121853 (Year: 2022). |
| Machine Translation of WO2017010560 (Year: 2022). |
| Japanese Notice of Reasons for Refusal for corresponding Japanese Application No. 2019-546725, dated Apr. 27, 2021, with an English translation. |
| Japanese Notice of Reasons for Refusal for corresponding Japanese Application No. 2019-546725, dated Jan. 11, 2022, with an English translation. |
| International Preliminary Report on Patentability and Written Opinion of the International Searching Authority (Forms PCT/IB/326, PCT/IB/373 and PCT/ISA/237) for International Application No. PCT/JP2018/036854, dated Apr. 16, 2020, with English translation. |
| International Search Report (Form PCT/ISA/210) for International Application No. PCT/JP2018/036854, dated Jan. 15, 2019, with English translation. |
| Chinese Office Action and Search Report for corresponding Chinese Application No. 201860064180.6, dated Jun. 17, 2021, with an English translation. |
| Number | Date | Country | |
|---|---|---|---|
| 20200231874 A1 | Jul 2020 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | PCT/JP2018/036854 | Oct 2018 | US |
| Child | 16837726 | US |
