JP7112332B2 - Photocrosslinkable liquid crystalline polymer and method for producing photocrosslinkable liquid crystalline polymer - Google Patents

Description

TECHNICAL FIELD The present invention relates to a photocrosslinkable liquid crystalline polymer and a method for producing a photocrosslinkable liquid crystalline polymer.

A liquid crystalline polymer having a mesogenic group in its molecular structure changes its physical properties as the degree of orientation of the liquid crystal (mesogenic group) changes. Focusing on such properties, attempts have been made to utilize liquid crystalline polymers as elastomers in various applications.

For example, as a liquid crystalline polymer, there is a liquid crystalline polyurethane elastomer obtained by reacting a diisocyanate component, a high-molecular-weight polyol component, and a mesogen diol (see, for example, Patent Document 1). The liquid crystalline polyurethane elastomer of Patent Document 1 was developed by the present applicant, and has rubber elasticity in the liquid crystal manifestation temperature range. This liquid crystalline polyurethane elastomer has a lower liquid crystal appearance temperature than conventional liquid crystalline polyurethanes.

JP 2014-172967 A

In order to obtain a liquid crystalline polymer, it is necessary to cure (crosslink) the raw material of the liquid crystalline polymer in the liquid crystal manifestation temperature range (liquid crystal phase). Further, in order to make the liquid crystalline polymer industrially easy to use, it is required that it can be processed into various shapes while maintaining the liquid crystal phase.

In this regard, the liquid crystalline polymer of Patent Document 1 is designed to lower the temperature at which liquid crystals appear, as described above. A high molecular weight polyol component having 3 or more hydroxyl groups is used as the high molecular weight polyol component. In this way, by using raw materials containing many crosslinkable functional groups, the cross-linking reaction proceeds between the raw materials while maintaining the liquid crystal phase during the thermoforming process, resulting in a liquid crystalline polymer (liquid crystalline elastomer) with rubber elasticity. ) can be obtained.

However, in the method in which the cross-linking reaction proceeds during the thermoforming process (that is, the thermosetting method), the melt viscosity of the polymer increases as the cross-linking progresses, making it difficult to control the reaction. In addition, there is a possibility that the raw material of the liquid crystalline polymer may harden early inside the molding machine. For this reason, in the industrial production of liquid crystalline polymers, improvement measures are required so that continuous production is not hindered by an increase in melt viscosity of the polymer or premature hardening of the raw material.

Accordingly, the present inventors have made various studies from the viewpoint of raw materials for liquid crystalline polymers in order to improve the above-mentioned concerns found in liquid crystalline polymers produced by conventional thermosetting methods. In the liquid crystalline polymer of Patent Document 1, molding and curing (crosslinking) of the raw material are simultaneously performed inside the molding machine. It is thought that there is no fear of an increase in the melt viscosity of the polymer inside and the hardening of the raw material, and it is possible to cope with industrial continuous production.

An object of the present invention is to provide a new liquid crystalline polymer produced by separating molding and curing (crosslinking). Another object of the present invention is to provide a method for producing such a novel liquid crystalline polymer.

The characteristic configuration of the photocrosslinkable liquid crystalline polymer according to the present invention for solving the above problems is
It is to include a reaction product of a mesogenic group-containing compound having an active hydrogen group, an isocyanate compound, a photopolymerizable group-containing compound, and a photocuring initiator.

The present inventors have studied a photocrosslinkable (photocurable) liquid crystalline polymer as a new liquid crystalline polymer produced without using a thermosetting method. If the photocrosslinkable liquid crystalline polymer is used, molding of the raw material and photocrosslinking (curing) can be performed as separate processes, so the melt viscosity of the polymer increases inside the molding machine and the raw material hardens. is prevented. Therefore, it becomes possible to continuously produce the liquid crystalline polymer, and it becomes possible to cope with industrial production.
Since the photocrosslinkable liquid crystalline polymer of this configuration is made by reacting a mesogenic group-containing compound having an active hydrogen group, an isocyanate compound, a photopolymerizable group-containing compound, and a photocuring initiator, the application range is It is obtained as a wide liquid crystalline polyurethane, can be easily molded even in a low temperature range including room temperature, and the entire polymer is evenly cured. Moreover, since the raw material can be cured in a state where the temperature after molding is sufficiently lowered (i.e., a state in which a liquid crystal phase is expressed), it becomes easy to form a monodomain, and the resulting photocrosslinkable liquid crystalline polymer The liquid crystal phase manifestation temperature range is a relatively low temperature range including room temperature. A photocrosslinkable liquid crystalline polymer having such low-temperature liquid crystal development properties can be suitably used, for example, as a thermoresponsive material utilizing a phase transition between a liquid crystal phase and an isotropic phase.

（ここで、Ｘは活性水素基であり、Ｒ_１は隣接する結合基の一部をなす単結合、－Ｎ＝Ｎ－、－ＣＯ－、－ＣＯ－Ｏ－、又は－ＣＨ＝Ｎ－であり、Ｒ_２は隣接する結合基の一部をなす単結合、又は－Ｏ－であり、Ｒ_３は隣接する結合基の一部をなす単結合、又は炭素数１～２０のアルキレン基である。ただし、Ｒ_２が－Ｏ－であり、且つＲ_３が隣接する結合基の一部をなす単結合であるものを除く。）
で表される化合物であることが好ましい。In the photocrosslinkable liquid crystalline polymer according to the present invention,
The mesogenic group-containing compound having an active hydrogen group has the following general formula (1):

(Where X is an active hydrogen group, R ₁ is a single bond forming part of the adjacent bonding group, -N=N-, -CO-, -CO-O-, or -CH=N- , R ₂ is a single bond forming part of the adjacent bonding group, or -O-, and R ₃ is a single bond forming part of the adjacent bonding group, or an alkylene group having 1 to 20 carbon atoms. (Excluding those in which R ₂ is —O— and R ₃ is a single bond forming part of the adjacent bonding group.)
It is preferably a compound represented by.

According to the photocrosslinkable liquid crystalline polymer of this configuration, since the compound having the above-described appropriate structure is used as the mesogenic group-containing compound having an active hydrogen group, it is practical to have liquid crystallinity in a low temperature range including room temperature. can produce a photocrosslinkable liquid crystalline polymer with a high

In the photocrosslinkable liquid crystalline polymer according to the present invention,
The photopolymerizable group-containing compound is preferably at least one selected from the group consisting of acryloyl group-containing compounds, methacryloyl group-containing compounds, and allyl group-containing compounds.

According to the photocrosslinkable liquid crystalline polymer of this configuration, since the above-mentioned suitable compound is used as the photopolymerizable group-containing compound, the photocrosslinking reaction by light irradiation proceeds rapidly and reliably, and low-temperature liquid crystal appears. It is possible to produce a photocrosslinkable liquid crystalline polymer having both properties and rubber elasticity.

In the photocrosslinkable liquid crystalline polymer according to the present invention,
It is preferable to contain the photopolymerizable group-containing compound in an amount of 1 to 10% by weight.

According to the photocrosslinkable liquid crystalline polymer of this configuration, by containing 1 to 10% by weight of the photopolymerizable group-containing compound, a photocrosslinkable liquid crystalline polymer having an excellent balance between low-temperature liquid crystal development and rubber elasticity can be obtained. can be made.

The characteristic configuration of the method for producing a photocrosslinkable liquid crystalline polymer according to the present invention for solving the above problems is as follows:
A mixing step of mixing a mesogenic group-containing compound having an active hydrogen group, an isocyanate compound, a photopolymerizable group-containing compound, and a photocuring initiator;
an irradiation step of irradiating the mixture obtained in the mixing step with light having a wavelength of 200 to 600 nm;
to include

According to the method for producing a photocrosslinkable liquid crystalline polymer of this configuration, the mixture can be easily molded even in a low temperature range including room temperature, and the entire polymer can be uniformly cured. In addition, since the mixture can be cured by irradiating light in a state where the temperature is sufficiently lowered after molding (that is, a state in which a liquid crystal phase is developed), it becomes easy to form a monodomain, and the generated photocrosslinking The liquid crystalline polymer exhibits a liquid crystal phase in a relatively low temperature range including room temperature. In addition, in the method for producing a photocrosslinkable liquid crystalline polymer of this configuration, since the raw material contains an isocyanate compound, liquid crystalline polyurethane, which has a wide range of applications as a liquid crystalline polymer, can be produced.

In the method for producing a photocrosslinkable liquid crystalline polymer according to the present invention,
It is preferable to include a stretching step of stretching the mixture obtained in the mixing step before the irradiation step.

According to the method for producing a photocrosslinkable liquid crystalline polymer of this configuration, the irradiation step is performed in a state in which the mesogenic groups contained in the mesogenic group-containing compound are aligned in the stretching direction by the stretching step, so that the orientation is maintained. A photocrosslinking reaction proceeds between the raw materials, and a liquid crystalline polymer having both low-temperature liquid crystalline property and elasticity can be obtained. In addition, since the orientation of the liquid crystal is enhanced by the stretching process, the phase transition between the liquid crystal phase and the isotropic phase becomes clear, and a material with excellent thermal responsiveness can be produced.

The photocrosslinkable liquid crystalline polymer of the present invention is described below. However, the present invention is not intended to be limited to the configurations described in the following embodiments.

<Photocrosslinkable liquid crystalline polymer>
The photocrosslinkable liquid crystalline polymer of the present invention comprises a mesogenic group-containing compound having an active hydrogen group (hereinafter simply referred to as "mesogenic group-containing compound"), an isocyanate compound, a photopolymerizable group-containing compound, and a photocuring initiator. is a liquid crystalline polyurethane elastomer obtained by reacting these four raw materials. The photocrosslinkable liquid crystalline polymer (liquid crystalline polyurethane elastomer) of the present invention has liquid crystallinity resulting from the mesogenic group-containing compound and elasticity resulting from the reaction of the mesogenic group-containing compound with the isocyanate compound and the photopolymerizable group-containing compound. The physical properties change due to the phase transition of the liquid crystal, and the temperature range where the liquid crystal phase appears is a relatively low temperature range including room temperature. A liquid crystalline polymer having such a low-temperature liquid crystal development property exhibits a specific behavior in which the physical properties change due to the phase transition of the liquid crystal. It can be suitably used as a thermoresponsive material.

In the following embodiments, the photocrosslinkable liquid crystalline polymer (liquid crystalline polyurethane elastomer) of the present invention, and the mesogenic group-containing compound, the isocyanate compound, the photopolymerizable group-containing compound, and the photocuring initiator that are raw materials thereof will be described. .

[Mesogenic group-containing compound]
As the mesogenic group-containing compound, for example, a compound represented by the following general formula (1) is used.

In the general formula (1), X is an active hydrogen group, R ₁ is a single bond forming part of the adjacent bonding group, -N=N-, -CO-, -CO-O-, or -CH= N—, R ₂ is a single bond forming part of the adjacent bonding group, or —O—, and R ₃ is a single bond forming part of the adjacent bonding group, or alkylene having 1 to 20 carbon atoms is the base. However, those in which R ₂ is —O— and R ₃ is a single bond forming part of the adjacent bonding group are excluded. The “single bond forming a part of the adjacent bonding group” means a state in which the single bond is shared with a part of the adjacent bonding group. For example, in the above general formula (1), when R ₁ is a single bond that forms part of the adjacent bonding group, the single bond R ₁ is shared with the benzene rings on both sides, and the benzene on both sides Forms a biphenyl structure with the ring. Examples of X include OH, SH, NH ₂ , COOH, secondary amine and the like. The compounding amount of the mesogenic group-containing compound is adjusted to 30 to 80% by weight, preferably 40 to 70% by weight, based on the total raw material of the photocrosslinkable liquid crystalline polymer. When the compounding amount of the mesogenic group-containing compound is less than 30% by weight, it becomes difficult for the resulting polymer to exhibit liquid crystallinity. When the compounding amount of the mesogenic group-containing compound exceeds 80% by weight, the phase transition temperature (Ti) between the liquid crystal phase and the isotropic phase becomes high, making it difficult to mold the polymer at low temperatures including room temperature.

It is preferable to use alkylene oxide and/or styrene oxide in combination with the mesogenic group-containing compound. Alkylene oxide and/or styrene oxide function to lower the temperature at which liquid crystallinity develops in a photocrosslinkable liquid crystalline polymer. A liquid crystalline polymer can be a product with excellent practicality at room temperature. Alkylene oxides can be used, for example ethylene oxide, propylene oxide, or butylene oxide. The alkylene oxides listed above may be used alone or in combination of multiple types. Styrene oxide may have a substituent such as an alkyl group, an alkoxy group, or a halogen on the benzene ring. As the alkylene oxide, it is also possible to use a mixture of the above alkylene oxide and the above styrene oxide. The amount of alkylene oxide and/or styrene oxide is adjusted so that 1 to 10 mol, preferably 2 to 6 mol, of alkylene oxide and/or styrene oxide is added to 1 mol of the mesogenic group-containing compound. When the number of added moles of alkylene oxide and/or styrene oxide is less than 1 mol, it becomes difficult to sufficiently lower the temperature range in which the photocrosslinkable liquid crystalline polymer exhibits liquid crystallinity. It becomes difficult to continuously mold a liquid crystalline polymer (liquid crystalline polyurethane) in a state where is expressed. If the number of moles of alkylene oxide and/or styrene oxide to be added exceeds 10 moles, it may be difficult for the photocrosslinkable liquid crystalline polymer to exhibit liquid crystallinity.

[Isocyanate compound]
As the isocyanate compound, for example, a diisocyanate compound or a trifunctional or higher isocyanate compound can be used. Examples of diisocyanate compounds include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 2,2′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 4,4′-diphenylmethane diisocyanate, and 1,5-naphthalene diisocyanate. , aromatic diisocyanates such as p-phenylene diisocyanate, m-phenylene diisocyanate, p-xylylene diisocyanate, and m-xylylene diisocyanate, ethylene diisocyanate, 2,2,4-trimethylhexamethylene-1,6-diisocyanate, 2, aliphatic diisocyanates such as 4,4-trimethylhexamethylene-1,6-diisocyanate and 1,6-hexamethylene diisocyanate, as well as 1,4-cyclohexane diisocyanate, 4,4′-dicyclohexylmethane diisocyanate, isophorone diisocyanate, and alicyclic diisocyanates such as norbornane diisocyanate. The above-listed diisocyanate compounds may be used singly or in combination of multiple types. Examples of tri- or higher functional isocyanate compounds include triphenylmethane triisocyanate, tris(isocyanatophenyl)thiophosphate, lysine ester triisocyanate, 1,3,6-hexamethylene triisocyanate, 1,6,11-undecane triisocyanate, triisocyanates such as 1,8-diisocyanate-4-isocyanatomethyloctane, bicycloheptane triisocyanate, and tetraisocyanates such as tetraisocyanatosilane. The tri- or more functional isocyanate compounds listed above may be used alone, or may be used in combination of multiple types. As the isocyanate compound, it is also possible to use a mixture of the above diisocyanate compound and the above trifunctional or higher isocyanate compound. The amount of the isocyanate compound is adjusted to 10 to 40% by weight, preferably 15 to 30% by weight, based on the total raw materials for the photocrosslinkable liquid crystalline polymer. When the amount of the isocyanate compound is less than 10% by weight, the polymerization by the urethane reaction is insufficient, making it difficult to continuously mold the liquid crystalline polymer (liquid crystalline polyurethane). When the amount of the isocyanate compound exceeds 40% by weight, the amount of the mesogenic group-containing compound in the entire raw material of the photocrosslinkable liquid crystalline polymer is relatively small, so the liquid crystallinity of the liquid crystalline polymer (liquid crystalline polyurethane) is reduced. decreases.

[Photopolymerizable group-containing compound]
As the photopolymerizable group-containing compound, for example, an acryloyl group-containing compound, a methacryloyl group-containing compound, and an allyl group-containing compound can be used. Examples of acryloyl group-containing compounds include propylene glycol diglycidyl ether acrylic acid adduct, ethylene glycol diglycidyl ether methacrylic acid adduct, tripropylene glycol diglycidyl ether acrylic acid adduct, glycerol diglycidyl ether acrylic acid adduct, and bisphenol A. PO2mol adduct diglycidyl ether acrylic acid adduct, 2-acryloyloxyethyl succinate, β-carboxyethyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxybutyl acrylate, 2-hydroxy-3-phenoxy Propyl acrylate, 2-acryloyloxyethyl-succinic acid, 2-acryloyloxyethylhexahydrophthalate, 2-acryloyloxyethyl-phthalate, 2-acryloyloxyethyl-2-hydroxyethyl-phthalate, 2 -acryloyloxyethyl acid phosphate, 2-hydroxy-3-acryloyloxypropyl methacrylate, pentaerythritol triacrylate and the like. Examples of methacryloyl group-containing compounds include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 2-methacryloyloxyethyl succinate, 2-methacryloyloxyethylhexahydrophthalate, and 2-methacryloyl. oxyethyl acid phosphate, glycerin dimethacrylate, bisphenol A PO2mol adduct diglycidyl ether methacrylic acid adduct, bisphenol A diglycidyl ether methacrylic acid adduct, 2-hydroxy-3-acryloyloxypropyl methacrylate, 2-methacryloyloxyethyl succinate and the like. Examples of allyl group-containing compounds include glycerin monoallyl ether, trimethylolpropane diallyl ether, pentaerythritol triallyl ether, and the like. The compounding amount of the photopolymerizable group-containing compound is adjusted to be 0.1 to 10% by weight, preferably 0.3 to 7% by weight, based on the total raw material of the photocrosslinkable liquid crystalline polymer. If the amount of the photopolymerizable group-containing compound is less than 0.1% by weight, even if the raw material is irradiated with light, it will not be sufficiently cured, so that the generated polymer will hardly exhibit thermal responsiveness. If the amount of the photopolymerizable group-containing compound exceeds 10% by weight, the crosslink density in the polymer after light irradiation becomes too high, and in this case as well, the resulting polymer is difficult to exhibit thermal responsiveness.

[Photocuring initiator]
Photocuring initiators are, for example, 1-hydroxy-cyclohexyl-phenyl-ketone, bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide, 2,4,6-trimethylbenzoyl-diphenyl-phosphine oxide, 2,2-dimethoxy-1,2-diphenylethan-1-one, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1-hydroxy-cyclohexyl-phenyl-ketone/benzophenone, 1-[ 4-(2-hydroxyethoxy)-phenyl]-2-hydroxy-2-methyl-1-propan-1-one, 2-hydroxy-1-{4-[4-(2-hydroxy-2-methyl-propionyl )-benzyl]-phenyl}-2-methyl-propan-1-one, oxy-phenyl-acetic acid 2-[2-oxo-2-phenyl-acetoxy-ethoxy]-ethyl ester/oxy-phenyl-acetic Acid 2-[2-hydroxy-ethoxy]-ethyl ester, phenylglyoxylic acid methyl ester, 2-methyl-1-[4-(methylthio)phenyl]-2-morpholinopropan-1-one, 2-benzyl -2-dimethylamino-1-(4-morpholinophenyl)-butanone-1,2-dimethylamino-2-(4-methyl-benzyl)-1-(4-morpholin-4-yl-phenyl)-butane -1-one, bis(η ⁵ -2,4-cyclopentadien-1-yl)-bis(2,6-difluoro-3-(1H-pyrrol-1-yl)-phenyl)titanium, 1,2- Octanedione, 1-[4-(phenylthio)phenyl-, 2-(O-benzoyloxime)], ethanone, 1-[9-ethyl-6-(2-methylbenzoyl)-9H-carbazol-3-yl] -,1-(O-acetyloxime), iodonium, (4-methylphenyl)[4-(2-methylpropyl)phenyl]-hexafluorophosphate (1-)/propylene carbonate, triarylsulfonium hexafluorophosphate Phate, triarylsulfonium tetrakis-(pentafluorophenyl)borate, oximesulfonate-based photoacid generators can be used. The amount of the photocuring initiator is adjusted to 0.5 to 10% by weight, preferably 1 to 8% by weight, based on the total amount of raw materials for the photocrosslinkable liquid crystalline polymer. When the amount of the photocuring initiator is less than 0.5% by weight, the polymerization reaction does not proceed uniformly during light irradiation, or the curing becomes insufficient, so that the generated polymer becomes difficult to exhibit thermal responsiveness. . If the amount of the photocuring initiator is more than 10% by weight, the content of mesogenic groups in the produced polymer decreases, making it difficult to develop liquid crystallinity. The photocuring initiator preferably has an absorption wavelength of 200 to 600 nm. As long as the photocuring initiator has an absorption wavelength within the above range, the photocuring initiator absorbs light even if the photocrosslinkable liquid crystalline polymer or its raw material has low transparency (visible light transmittance). It can be absorbed, and the photocrosslinking reaction can be progressed reliably.

<Preparation of photocrosslinkable liquid crystalline polymer>
A photocrosslinkable liquid crystalline polymer is produced by irradiating a raw material containing a mesogenic group-containing compound, an isocyanate compound, a photopolymerizable group-containing compound, and a photocuring initiator with light. Specifically, the raw materials are kneaded and heated, molded into a predetermined shape using an extruder, and then irradiated with light to promote a photocrosslinking reaction between the raw materials and cure. The light with which the raw material is irradiated is preferably ultraviolet light or visible light with a wavelength of 200 to 600 nm. With such a curing method based on photocrosslinking, the raw material is kneaded, heated, stretched and molded, and then cured in a state where the temperature is sufficiently lowered by cooling. That is, molding and photocrosslinking (curing) can be performed as separate steps. Therefore, it is possible to obtain a photocrosslinkable liquid crystalline polymer that reliably exhibits a liquid crystal phase in a low temperature range.

The photocrosslinkable liquid crystalline polymer of the present invention can be easily molded even at low temperatures including room temperature, and the entire polymer can be uniformly cured. Moreover, since the raw material can be cured in a state in which the temperature is sufficiently lowered after molding (that is, in a state in which a liquid crystal phase is expressed), it becomes easy to form a monodomain, and the resulting photocrosslinkable liquid crystalline polymer can be cured. The temperature range in which the liquid crystal phase appears is a relatively low temperature range including room temperature.

The kneading and heating of the raw materials for the photocrosslinkable liquid crystalline polymer can be carried out simultaneously with the molding in the extruder. First, raw materials are put into an extruder and sufficiently kneaded and heated. Next, the kneaded melt is extruded while being stretched in a temperature range where liquid crystallinity is exhibited (that is, the glass transition temperature (T _g ) or higher and the phase transition temperature (T _i ) or lower). At this time, since the mesogenic groups contained in the mesogenic group-containing compound move along the stretching direction, a high degree of orientation is obtained. Then, when the stretched kneaded melt is molded into an appropriate shape and cooled, and irradiated with light with a wavelength of 200 to 600 nm while maintaining the stretched state, a cross-linking reaction proceeds between the raw materials while maintaining the orientation, resulting in a low-temperature liquid crystal. A photocrosslinkable liquid crystalline polymer having both developability and elasticity is completed. This is a continuous manufacturing method. On the other hand, the raw material of the photocrosslinkable liquid crystalline polymer is kneaded and heated in advance and molded into a pellet shape, and the pelletized raw material is molded into a predetermined shape using an extruder. Stretching in a region (that is, the glass transition temperature (T _g ) or more and the phase transition temperature (T _i ) or less), and irradiating light with a wavelength of 200 to 600 nm while maintaining the stretched state to produce a photocrosslinkable liquid crystalline polymer. is also possible. This is a batch production method. In the photocrosslinkable liquid crystalline polymer produced in this way, the mesogenic groups are oriented in the stretching direction in the low temperature region, but when the phase transition temperature (T _i ) is exceeded by heating, the orientation of the mesogenic groups collapses. It shrinks (becomes disordered) in the drawing direction, and when cooled below the phase transition temperature (T _i ), the orientation of the mesogenic groups is restored and stretches in the drawing direction, exhibiting a specific thermally responsive behavior.

Incidentally, the orientation of the photocrosslinkable liquid crystalline polymer can be evaluated by the degree of orientation of the mesogenic groups. A large value of the degree of orientation indicates that the mesogenic groups are highly oriented uniaxially. The degree of orientation is determined by the single total reflection measurement (ATR) using a Fourier transform infrared spectrophotometer (FT-IR), the absorbance of the antisymmetric stretching vibration of the aromatic ether (0 °, 90 °), and the methyl The absorbance of the symmetric bending vibration of the group (0°, 90°) is measured, and calculated based on the following formula using these absorbances as parameters.
Orientation = (AB) / (A + 2B)
A: absorbance of antisymmetric stretching vibration of aromatic ether when measured at 0°/absorbance of symmetric bending vibration of methyl group when measured at 0° B: reverse of aromatic ether when measured at 90° Absorbance of symmetric stretching vibration/absorbance of symmetric bending vibration of methyl group when measured at 90°

In order for the photocrosslinkable liquid crystalline polymer to exhibit significant stretchability, the degree of orientation of the mesogenic groups is preferably 0.05 or more, more preferably 0.1 or more.

A photocrosslinkable liquid crystalline polymer (liquid crystalline polyurethane elastomer) of the present invention was prepared and its properties were confirmed. In the following examples and comparative examples, the unit of the blending amount of each raw material is "g", but the present invention can be scaled up at any scale. That is, the unit of the blending amount of each raw material can be read as "parts by weight".

[Example 1]
In a reaction vessel, BH6 (500 g) in which R ₁ of formula (1) is a single bond as a mesogenic group-containing compound having an active hydrogen group, potassium hydroxide (19 g), and N,N-dimethylformamide (3000 ml) as a solvent is added and mixed, and 5 equivalents of propylene oxide is added as an alkylene oxide to 2 moles of BH6 (that is, 2.5 equivalents to 1 mole of BH6), and the mixture is subjected to pressurized conditions. , and 120° C. for 2 hours (addition reaction). Then, oxalic acid (15 g) was added to the reaction vessel to stop the addition reaction, insoluble salts in the reaction solution were removed by suction filtration, and N,N-dimethylformamide in the reaction solution was removed by distillation under reduced pressure. Mesogendiol A was obtained by removing by A synthesis scheme of mesogendiol A is shown in formula (2). Mesogendiol A shown in formula (2) is a representative one and may include various structural isomers.

Next, mesogen diol A (100 g), 2-hydroxyethyl acrylate (2 g) and propylene glycol diglycidyl ether acrylic acid adduct (1 g) as a photopolymerizable group-containing compound, 2,4,6- Trimethylbenzoyl-diphenyl-phosphine oxide (3 g) and 1,6-hexamethylene diisocyanate (35 g) as an isocyanate compound were mixed to prepare a raw material for a photocrosslinkable liquid crystalline polymer. This raw material was heated and melted at 80° C. while stirring, and after cooling, the resin was pulverized with a plastic pulverizer (product name: ZI-420, manufactured by Horai Co., Ltd.) and pelletized. Next, the resin pellets were put into a single-screw extruder (product name: SZW25GT-24MG-STD, manufactured by Technobell Co., Ltd.) set at 80 to 120° C. and formed into a resin sheet with a thickness of 1.0 mm. This resin sheet was passed through a cooling roll set at 15° C. to cool it to the glass transition temperature (Tg) or higher and the phase transition temperature (Ti) or lower, and wound up with a take-up roll. At this time, the resin sheet was stretched 1.5 to 10 times by providing a rotation difference between the cooling roll and the take-up roll. Furthermore, a tabletop UV curing device (product name: Eye mini grantage (ESC-1511U), manufactured by Eye Graphics Co., Ltd.) is installed between the cooling roll and the take-up roll, and the stretched resin sheet has a wavelength of 200 ~. A light of 600 nm was applied to obtain a photocrosslinked (cured) photocrosslinkable liquid crystalline polymer of Example 1.

[Example 2]
In preparing the raw materials for the photocrosslinkable liquid crystalline polymer, 2-hydroxyethyl acrylate (1.5 g) and propylene glycol diglycidyl ether acrylic acid adduct (6 g) as photopolymerizable group-containing compounds, and 1, as an isocyanate compound. 6-Hexamethylene diisocyanate (38 g) was added. Other raw materials, compounding amounts, and production conditions were the same as in Example 1, and a photocrosslinkable liquid crystalline polymer of Example 2 was obtained.

[Example 3]
In preparing the raw materials for the photocrosslinkable liquid crystalline polymer, 2-hydroxyethyl acrylate (1 g) and propylene glycol diglycidyl ether acrylic acid adduct (3 g) as photopolymerizable group-containing compounds, and 1,6- Hexamethylene diisocyanate (36 g) was added. Other raw materials, compounding amounts, and production conditions were the same as in Example 1, and a photocrosslinkable liquid crystalline polymer of Example 3 was obtained.

[Example 4]
In preparing the raw materials for the photocrosslinkable liquid crystalline polymer, propylene glycol diglycidyl ether acrylic acid adduct (8 g) and 2-hydroxyethyl methacrylate (2 g) as photopolymerizable group-containing compounds, and 1,6- Hexamethylene diisocyanate (39 g) was added. Other raw materials, compounding amounts, and production conditions were the same as in Example 1, and a photocrosslinkable liquid crystalline polymer of Example 4 was obtained.

[Example 5]
In preparing the raw materials for the photocrosslinkable liquid crystalline polymer, 2-hydroxyethyl acrylate (0.5 g) and glycerin monoallyl ether (2 g) as photopolymerizable group-containing compounds, and 1,6-hexamethylene diisocyanate as an isocyanate compound. (36 g) was added. Other raw materials, compounding amounts, and production conditions were the same as in Example 1, and a photocrosslinkable liquid crystalline polymer of Example 5 was obtained.

[Example 6]
Into a reaction vessel, BH6 (500 g) in which R ₁ of formula (1) is a single bond as a mesogenic group-containing compound having an active hydrogen group, potassium hydroxide (19 g), and N,N-dimethylformamide (3000 ml) as a solvent is added and mixed, and propylene oxide is added as an alkylene oxide in an amount of 5 equivalents per 4 moles of BH6 (i.e., 1.25 equivalents per mole of BH6), and the mixture is subjected to pressurized conditions. , and 120° C. for 2 hours (addition reaction). Then, oxalic acid (15 g) was added to the reaction vessel to stop the addition reaction, insoluble salts in the reaction solution were removed by suction filtration, and N,N-dimethylformamide in the reaction solution was removed by distillation under reduced pressure. Mesogen diol B was obtained by removing by A synthesis scheme of mesogendiol B is shown in Formula (3). Note that the mesogen diol B shown in formula (3) is a representative one and may include various structural isomers.

Next, mesogen diol B (100 g), 2-hydroxyethyl acrylate (1.5 g) and propylene glycol diglycidyl ether acrylic acid adduct (2 g) as a photopolymerizable group-containing compound, and 2, 4, and 4 as photocuring initiators. 6-trimethylbenzoyl-diphenyl-phosphine oxide (3 g) and 1,6-hexamethylene diisocyanate (41 g) as an isocyanate compound were mixed to prepare a raw material for a photocrosslinkable liquid crystalline polymer. Subsequent operations and production conditions were the same as in Example 1 to obtain a photocrosslinked (cured) photocrosslinkable liquid crystalline polymer of Example 6.

[Example 7]
Into a reaction vessel, BH6 (500 g) in which R ₁ of formula (1) is a single bond as a mesogenic group-containing compound having an active hydrogen group, potassium hydroxide (19 g), and N,N-dimethylformamide (3000 ml) as a solvent is added and mixed, and propylene oxide is added as an alkylene oxide in an amount of 3 equivalents per 4 moles of BH6 (i.e., 0.75 equivalents per 1 mole of BH6), and these mixtures are subjected to pressurized conditions. , and 120° C. for 2 hours (addition reaction). Then, oxalic acid (15 g) was added to the reaction vessel to stop the addition reaction, insoluble salts in the reaction solution were removed by suction filtration, and N,N-dimethylformamide in the reaction solution was removed by distillation under reduced pressure. Mesogendiol C was obtained by removing by A synthesis scheme of mesogendiol C is shown in Formula (4). The mesogen diol C shown in formula (4) is a representative one and may include various structural isomers.

Next, mesogen diol C (100 g), 2-hydroxyethyl acrylate (2 g) and propylene glycol diglycidyl ether acrylic acid adduct (2 g) as a photopolymerizable group-containing compound, 2,4,6- Trimethylbenzoyl-diphenyl-phosphine oxide (3 g) and 1,6-hexamethylene diisocyanate (44 g) as an isocyanate compound were mixed to prepare a raw material for a photocrosslinkable liquid crystalline polymer. Subsequent operations and production conditions were the same as in Example 1 to obtain a photocrosslinked (cured) photocrosslinkable liquid crystalline polymer of Example 7.

[Example 8]
In a reaction vessel, BHBA6 (500 g) in which R ₁ in formula (1) is -CH=N- as a mesogenic group-containing compound having an active hydrogen group, potassium hydroxide (19 g), and N,N-dimethylformamide as a solvent (3000 ml) was added and mixed, and 5 equivalents of propylene oxide as alkylene oxide were added to 2 moles of BHBA6 (that is, 2.5 equivalents to 1 mole of BHBA6), and the mixture was added. The reaction was carried out at 120° C. for 2 hours under pressure conditions (addition reaction). Then, oxalic acid (15 g) was added to the reaction vessel to stop the addition reaction, insoluble salts in the reaction solution were removed by suction filtration, and N,N-dimethylformamide in the reaction solution was removed by distillation under reduced pressure. Mesogen diol D was obtained by removing by A synthesis scheme of mesogen diol D is shown in formula (5). Note that the mesogen diol D shown in formula (5) is a representative one and may include various structural isomers.

Next, mesogen diol D (100 g), 2-hydroxyethyl acrylate (1 g) and propylene glycol diglycidyl ether acrylic acid adduct (3 g) as a photopolymerizable group-containing compound, 2,4,6- Trimethylbenzoyl-diphenyl-phosphine oxide (3 g) and 1,6-hexamethylene diisocyanate (34 g) as an isocyanate compound were mixed to prepare a raw material for a photocrosslinkable liquid crystalline polymer. Subsequent operations and production conditions were the same as in Example 1 to obtain a photocrosslinked (cured) photocrosslinkable liquid crystalline polymer of Example 8.

[Comparative Example 1]
In preparing the raw materials for the liquid crystalline polymer, 2-hydroxyethyl acrylate (0.1 g) as a photopolymerizable group-containing compound and 1,6-hexamethylene diisocyanate (33 g) as an isocyanate compound were blended. However, the resin sheet was not irradiated with light. A liquid crystalline polymer of Comparative Example 1 was obtained with the same conditions as in Example 1 with respect to other raw materials, compounding amounts, and production conditions.

[Comparative Example 2]
In preparing the raw materials for the liquid crystalline polymer, 2-hydroxyethyl acrylate (4 g) and propylene glycol diglycidyl ether acrylic acid adduct (16 g) were used as photopolymerizable group-containing compounds, and 1,6-hexamethylene diisocyanate was used as the isocyanate compound. (45 g) was added. However, the resin sheet was not irradiated with light. A liquid crystalline polymer of Comparative Example 2 was obtained by using the same other raw materials and compounding amounts as well as the manufacturing conditions as in Example 1.

[Characteristic evaluation of liquid crystalline elastomer raw material composition]
The photocrosslinkable liquid crystalline polymers of Examples 1 to 8 and the liquid crystalline polymers of Comparative Examples 1 and 2 were evaluated for extrudability of the liquid crystalline polymer before light irradiation. Further, for the photocrosslinkable liquid crystalline polymers of Examples 1 to 8, the glass transition temperature (Tg) and phase transition temperature (Ti) of the liquid crystalline polymer after light irradiation, and the expansion ratio were measured, and the presence or absence of thermal responsiveness was measured. It was confirmed. The measurement method and measurement conditions for each measurement item are described below.

<Extrudability>
The photocrosslinkable liquid crystalline polymers of Examples 1 to 8 and the liquid crystalline polymers of Comparative Examples 1 and 2 were visually evaluated for extrusion moldability. (○)”.

<Glass transition temperature (Tg)/phase transition temperature (Ti)>
For the photocrosslinkable liquid crystalline polymers of Examples 1 to 8, a differential scanning calorimeter [DSC] (product name: X-DSC 7000, manufactured by Hitachi High-Tech Science Co., Ltd.) was used to measure the glass transition of each sample after light irradiation. Temperature (Tg) and phase transition temperature (Ti) were measured. The rate of temperature increase during measurement was 20° C./min.

<Expansion rate/thermal responsiveness>
With respect to the photocrosslinkable liquid crystalline polymers of Examples 1 to 8, the sizes in the orientation direction in the liquid crystal phase (Ti-20°C) and the isotropic phase (Ti+20°C) were measured with a scale, and the expansion ratio was calculated by the following formula. . Those in which a decrease (shrinkage) in length was observed due to the phase transition from the liquid crystal phase to the isotropic phase were judged to be "thermally responsive (○)".
Stretch ratio (%) = (L ₁ - L ₂ )/L ₂ × 100
L ₁ : length (mm) in the alignment direction of the sample in the liquid crystal phase
L ₂ : Length (mm) in the orientation direction of the sample in the isotropic phase

The measurement results in Examples 1-8 and Comparative Examples 1-2 are summarized in Table 1 below.

All of the photocrosslinkable liquid crystalline polymers of Examples 1 to 8 had good extrudability even at low temperatures including room temperature. Therefore, it was possible to uniformly cure the entire liquid crystalline polymer by irradiating light after extrusion molding. Since the liquid crystalline polymer after light irradiation has a glass transition temperature (Tg) and a phase transition temperature (Ti) between room temperature (about 20 to 30° C.), it is a material with excellent usability. Moreover, the expansion ratio was 9 to 85%, and the thermoresponsiveness of the liquid crystalline polymer was confirmed in all the examples, suggesting that it is useful as a thermoresponsive material.

In contrast, the liquid crystalline polymer of Comparative Example 1 had poor extrusion moldability.

The liquid crystalline polymer of Comparative Example 2 was cured in the extruder and could not be discharged to the outside.

In the photocrosslinkable liquid crystalline polymer of the present invention, molding and curing (crosslinking) can be carried out separately, and as a result, there is no possibility that the raw material will harden inside the molding machine. It is also a highly practical material.

The photocrosslinkable liquid crystalline polymer of the present invention may be used in fields such as clothing products (fibers), actuators and filters.

Claims (4)

A photocrosslinkable liquid crystalline polymer composed of a pre-photocrosslinking reaction product of a mesogenic group-containing compound having an active hydrogen group, a diisocyanate compound, a photopolymerizable group-containing compound having a hydroxyl group, and a photocuring initiator. hand,
The mesogenic group-containing compound having an active hydrogen group has the following general formula (1):

(Where X is an active hydrogen group, R ₁ is a single bond forming part of the adjacent bonding group, -N=N-, -CO-, -CO-O-, or -CH=N- , R ₂ is a single bond forming part of the adjacent bonding group, or -O-, and R ₃ is a single bond forming part of the adjacent bonding group, or an alkylene group having 1 to 20 carbon atoms. (Excluding those in which R ₂ is —O— and R ₃ is a single bond forming part of the adjacent bonding group.)
is a compound represented by
A photocrosslinkable liquid crystalline polymer containing 1 to 10% by weight of the photopolymerizable group-containing compound having a hydroxyl group . 2. The photocrosslinkable liquid crystal according to claim 1, wherein the photopolymerizable group-containing compound having a hydroxyl group is at least one selected from the group consisting of an acryloyl group-containing compound, a methacryloyl group-containing compound, and an allyl group-containing compound. polymer. A mixing step of reacting while mixing a mesogenic group-containing compound having an active hydrogen group, a diisocyanate compound, a photopolymerizable group-containing compound having a hydroxyl group, and a photocuring initiator;
an irradiation step of irradiating the mixture obtained in the mixing step with light having a wavelength of 200 to 600 nm;
encompasses
The mesogenic group-containing compound having an active hydrogen group has the following general formula (1):

(Where X is an active hydrogen group, R ₁ is a single bond forming part of the adjacent bonding group, -N=N-, -CO-, -CO-O-, or -CH=N- , R ₂ is a single bond forming part of the adjacent bonding group, or -O-, and R ₃ is a single bond forming part of the adjacent bonding group, or an alkylene group having 1 to 20 carbon atoms. (Excluding those in which R ₂ is —O— and R ₃ is a single bond forming part of the adjacent bonding group.)
is a compound represented by
A method for producing a photocrosslinkable liquid crystalline polymer containing 1 to 10% by weight of the photopolymerizable group-containing compound having a hydroxyl group . 4. The method for producing a photocrosslinkable liquid crystalline polymer according to claim 3, further comprising a stretching step of stretching the mixture obtained in the mixing step before the irradiation step.