JP6629991B2 - Liquid crystalline elastomer raw material composition - Google Patents

Description

  The present invention relates to a liquid crystalline elastomer raw material composition for producing a liquid crystalline elastomer.

  The physical properties of a liquid crystalline polymer having a mesogen group in the molecular structure change with a change in the degree of orientation of the liquid crystal (mesogen group). Focusing on such properties, attempts have been made to use liquid crystal 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 mesogendiol (for example, see Patent Document 1). The liquid crystal polyurethane elastomer disclosed in Patent Document 1 has been developed by the present applicant and has rubber elasticity in a liquid crystal development temperature region. This liquid crystalline polyurethane elastomer has a lower liquid crystal development temperature than the conventional liquid crystalline polyurethane.

JP 2014-172967 A

  In order to obtain a liquid crystalline elastomer, it is necessary to cure (crosslink) the raw material of the liquid crystalline elastomer in a liquid crystal development temperature region (liquid crystal phase). Further, in order to make the liquid crystalline elastomer easily industrially usable, it is required that the liquid crystalline elastomer can be processed into various shapes while maintaining the liquid crystal phase.

  In this regard, the liquid crystalline elastomer of Patent Document 1 is designed to lower the liquid crystal development temperature as described above, and as a means for using tri- or more-functional isocyanate as an isocyanate component, A high molecular weight polyol component having 3 or more hydroxyl groups is used as the high molecular weight polyol component. As described above, by using a raw material having a large number of crosslinkable functional groups, a cross-linking reaction proceeds between the raw materials while maintaining a liquid crystal phase during thermoforming, thereby obtaining a liquid crystalline elastomer having rubber elasticity. it can.

  However, in a method in which a crosslinking reaction proceeds during thermoforming (that is, a thermosetting method), a raw material of a liquid crystalline elastomer may be cured early in a molding machine, and it is difficult to adjust molding conditions. was there. For this reason, in the industrial production of liquid crystalline elastomers, there is a demand for an improvement measure in which continuous production is not hindered by early curing of raw materials.

  Then, the present inventors conducted various studies from the viewpoint of the raw materials of the liquid crystalline elastomer in order to improve the above-mentioned concerns observed in the liquid crystalline elastomer obtained by the conventional thermosetting method. The liquid crystalline elastomer disclosed in Patent Document 1 performs molding and curing (crosslinking) of raw materials at the same time inside a molding machine. However, if molding and curing (crosslinking) can be performed separately, the molding machine can be used. It is considered that there is no possibility that the raw material is hardened inside, and it is possible to cope with industrial continuous production.

  An object of the present invention is to provide a new liquid crystal elastomer raw material composition for producing a liquid crystal elastomer.

Characteristic constitution of the liquid crystalline elastomer raw material composition according to the present invention for solving the above problems,
A mesogen group-containing compound having an active hydrogen group, a photopolymerizable group-containing compound, and a liquid crystal elastomer raw material composition including a photocuring initiator,
When a film is formed to a thickness of 0.5 mm, the light transmittance at a wavelength of 500 to 800 nm is 50% or more in the entire wavelength range, and the light transmittance at a wavelength of 380 nm is 20% or less.

The present inventors have studied a liquid crystalline elastomer raw material containing a photocurable material as a new liquid crystalline elastomer raw material composition for producing a liquid crystalline elastomer. After molding the liquid crystal elastomer raw material composition of this configuration (a mesogen group-containing compound having an active hydrogen group, a photopolymerizable group-containing compound, and a photocuring initiator) using a molding machine, light having an appropriate wavelength is emitted. If irradiation is performed and the photocrosslinking reaction proceeds between the raw materials, the molding and curing of the raw materials are performed as separate steps, so that the raw materials are prevented from being cured inside the molding machine. Therefore, it is possible to continuously produce the liquid crystalline elastomer, and it is possible to cope with industrial production.
Here, in order to cure the raw material by photocrosslinking, it is necessary to allow light to reach inside the raw material. Therefore, in the liquid crystal elastomer raw material composition of the present configuration, when the liquid crystal elastomer raw material composition is formed into a film having a thickness of 0.5 mm, the light transmittance at a wavelength of 500 to 800 nm is 50% or more in the entire wavelength range. The light transmittance at a wavelength of 380 nm was set to be 20% or less. In this case, in the liquid crystal elastomer produced from the liquid crystal elastomer raw material composition of the present configuration, since the photocrosslinking reaction has sufficiently proceeded from the surface to the inside, the entire liquid crystal elastomer is uniformly cured. In addition, since the raw material can be cured in a state where the temperature after molding is sufficiently lowered (that is, a state in which a liquid crystal phase is developed), it is easy to form a monodomain, and the liquid crystal phase of the generated liquid crystalline elastomer is easily formed. Is a relatively low temperature range including room temperature. Such a liquid crystalline elastomer having a low-temperature liquid crystal development property can be suitably used, for example, as a thermoresponsive material utilizing a phase transition between a liquid crystal phase and an isotropic phase.

In the liquid crystalline elastomer raw material composition according to the present invention,
In the light transmittance at the wavelength of 500 to 800 nm, it is preferable that the difference between the maximum light transmittance and the minimum light transmittance is 20% or less.

  According to the liquid crystal elastomer raw material composition of this configuration, the difference between the maximum light transmittance and the minimum light transmittance in the light transmittance at a wavelength of 500 to 800 nm is set to be 20% or less. Thus, the photocrosslinking reaction between the raw materials can be sufficiently and efficiently advanced.

  In the liquid crystalline elastomer raw material composition according to the present invention, the photocuring initiator preferably has an absorption wavelength in the range of 200 to 600 nm.

  According to the liquid crystal elastomer raw material composition of this configuration, by setting the absorption wavelength of the photocuring initiator to 200 to 600 nm, even if the liquid crystal elastomer or the raw material has low transparency (visible light transmittance). In addition, the photo-curing initiator absorbs light, and the photo-crosslinking reaction can reliably proceed.

  The liquid crystalline elastomer raw material composition according to the present invention preferably further contains an isocyanate compound.

  According to the liquid crystal elastomer raw material composition of the present configuration, by further containing an isocyanate compound, a liquid crystal polyurethane elastomer having a wide range of applications as a liquid crystal elastomer can be produced.

（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 liquid crystalline elastomer raw material composition according to the present invention,
The mesogen group-containing compound having an active hydrogen group is represented by the following general formula (1):

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

  According to the liquid crystal elastomer raw material composition of the present configuration, since the compound having the above-described appropriate structure is used as the mesogen group-containing compound having an active hydrogen group, it has practicality having liquid crystallinity in a low temperature region including room temperature. , A liquid crystalline elastomer having a high viscosity can be produced.

  Hereinafter, the liquid crystalline elastomer raw material composition of the present invention will be described. However, the present invention is not intended to be limited to the configurations described in the following embodiments.

<Liquid crystal elastomer raw material composition>
The liquid crystal elastomer raw material composition of the present invention contains a mesogen group-containing compound having an active hydrogen group (hereinafter, simply referred to as “mesogen group-containing compound”), a photopolymerizable group-containing compound, and a photocuring initiator. . When the liquid crystal elastomer raw material composition is reacted, a liquid crystal elastomer having both liquid crystallinity generated from the mesogen group-containing compound and elasticity generated by the reaction between the mesogen group-containing compound and the photopolymerizable group-containing compound is obtained. Can be generated. The physical properties of the liquid crystalline elastomer change due to the phase transition of the liquid crystal, and the temperature range in which the liquid crystal phase appears is a relatively low temperature range including room temperature. A liquid crystalline elastomer having such a low-temperature liquid crystal manifestation exhibits a specific behavior in which physical properties are changed by a phase transition of a liquid crystal, and, for example, utilizes a phase transition between a liquid crystal phase and an isotropic phase. It can be suitably used as a thermoresponsive material.

  The liquid crystalline elastomer raw material composition may further contain an additional compound in addition to the mesogen group-containing compound, the photopolymerizable group-containing compound, and the photocuring initiator. For example, in addition to the above three compounds, an isocyanate compound can be further included. In this case, when the liquid crystalline elastomer raw material composition is reacted, a liquid crystalline polyurethane elastomer is obtained as the liquid crystalline elastomer. Since the liquid crystalline polyurethane elastomer is excellent in elasticity, it can be used, for example, as a material for functional fibers or actuators utilizing a phase transition between a liquid crystal phase and an isotropic phase. Examples of other compounds that can be added include ester compounds, silane alkoxides, and acrylic compounds. When the liquid crystalline elastomer raw material composition further contains an ester compound, a liquid crystalline polyester elastomer is obtained. When the composition further contains a silane alkoxide, a liquid crystalline polysiloxane elastomer is obtained. When it further contains an acrylic compound, a liquid crystalline polyacrylate elastomer is obtained. Each of these liquid crystalline elastomers is a polymer material having both liquid crystallinity and elasticity, and exhibits a specific behavior in which physical properties are changed by phase transition of liquid crystal.

  In the following embodiments, as typical examples, a mesogen group-containing compound, a photopolymerizable group-containing compound, a photocuring initiator, and a liquid crystal elastomer raw material composition containing an isocyanate compound, and a liquid crystal elastomer raw material composition produced from the liquid crystal elastomer raw material composition The liquid crystalline polyurethane elastomer will be described.

(Mesogen group-containing compound)
As the mesogen group-containing compound, for example, a compound represented by the following general formula (1) can be used.

In the general formula (1), X is an active hydrogen group, R ₁ is a single bond forming a part of an adjacent bonding group, -N = N-, -CO-, -CO-O-, or -CH = N-, R ₂ is a single bond forming a part of an adjacent bonding group, or —O—, R ₃ is a single bond forming a part of an adjacent bonding group, or an alkylene having 1 to 20 carbon atoms. Group. However, it excludes those in which R ₂ is —O— and R ₃ is a single bond that forms part of an adjacent bonding group. The “single bond forming a part of the adjacent bonding group” means a state where 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 an adjacent bonding group, the single bond R ₁ is shared with the benzene rings on both sides, and the benzene ring on both sides is used. Forms a biphenyl structure with the ring. X includes, for example, OH, SH, NH ₂ , COOH, and secondary amine. The compounding amount of the mesogen group-containing compound is adjusted so as to be 30 to 80% by weight, preferably 40 to 70% by weight in the whole liquid crystalline elastomer raw material composition. If the compounding amount of the mesogen group-containing compound is less than 30% by weight, it is difficult for the polymer (elastomer) to exhibit liquid crystallinity. When the compounding amount of the mesogen group-containing compound exceeds 80% by weight, the phase transition temperature (Ti) between the liquid crystal phase and the isotropic phase becomes high, and it becomes difficult to mold a polymer (elastomer) in a low temperature range including normal temperature. .

  It is preferable to use an alkylene oxide and / or styrene oxide in combination with the mesogen group-containing compound. Since the alkylene oxide and / or styrene oxide functions to lower the liquid crystallinity manifestation temperature in the liquid crystal polyurethane elastomer, the liquid crystal polyurethane elastomer produced by using the mesogen group-containing compound in combination with the alkylene oxide and / or styrene oxide is It can be a product excellent in practicality at normal temperature. As the alkylene oxide, for example, ethylene oxide, propylene oxide, or butylene oxide can be used. The above-mentioned alkylene oxides may be used alone or in combination of two or more. 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, a mixture of the above-mentioned alkylene oxide and the above-mentioned styrene oxide can be used. The blending amount of the alkylene oxide and / or styrene oxide is adjusted so that 1 to 10 mol, preferably 2 to 6 mol of the alkylene oxide and / or styrene oxide is added to 1 mol of the mesogen group-containing compound. When the addition mole number of the alkylene oxide and / or styrene oxide is less than 1 mol, it is difficult to sufficiently lower the temperature range in which the liquid crystalline polyurethane elastomer exhibits liquid crystallinity, and therefore, the liquid crystalline polyurethane elastomer exhibits no liquid crystallinity. In such a state, it becomes difficult to continuously form the liquid crystalline polyurethane elastomer. When the number of added moles of the alkylene oxide and / or styrene oxide exceeds 10 moles, the liquid crystal polyurethane elastomer may not easily exhibit liquid crystallinity.

(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 the acryloyl group-containing compound include propylene glycol diglycidyl ether acrylate, ethylene glycol diglycidyl ether methacrylate, tripropylene glycol diglycidyl ether acrylate, glycerin diglycidyl ether acrylate, and bisphenol A. PO 2 mol 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-acryloyloxyethyl hexahydrophthalic acid, 2-acryloyl Rokishiechiru - phthalic acid, 2-acryloyloxyethyl-2-hydroxyethyl - phthalic acid, 2-acryloyloxyethyl acid phosphate, 2-hydroxy-3-acryloyloxy propyl methacrylate, pentaerythritol triacrylate and the like. Examples of the methacryloyl group-containing compound include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 2-methacryloyloxyethyl succinic acid, 2-methacryloyloxyethyl hexahydrophthalic acid, and 2-methacryloyl. Roxyethyl acid phosphate, glycerin dimethacrylate, bisphenol A PO 2 mol 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 the allyl group-containing compound include glycerin monoallyl ether, trimethylolpropane diallyl ether, and pentaerythritol triallyl ether. The compounding amount of the photopolymerizable group-containing compound is adjusted so as to be 0.1 to 10% by weight, preferably 0.3 to 7% by weight in the whole liquid crystal elastomer raw material composition. When the compounding amount of the photopolymerizable group-containing compound is less than 0.1% by weight, the raw material is not sufficiently cured even when irradiated with light, so that the produced polymer (elastomer) hardly exhibits heat responsiveness. When the compounding amount of the photopolymerizable group-containing compound exceeds 10% by weight, the crosslink density in the polymer (elastomer) after light irradiation becomes too high, so that the formed polymer (elastomer) also exhibits heat responsiveness. It becomes difficult to do.

(Photocuring initiator)
Photocuring initiators include, for example, 1-hydroxy-cyclohexyl-phenyl-ketone, bis (2,4,6-trimethylbenzoyl) -phenylphosphon 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-acetyl 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) -butan-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- (f Nilthio) 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, triarylsulfonium tetrakis- ( (Pentafluorophenyl) borate and oxime sulfonate photoacid generators can be used. The compounding amount of the photocuring initiator is adjusted so as to be 0.5 to 10% by weight, preferably 1 to 8% by weight in the whole liquid crystalline elastomer raw material composition. If the compounding amount of the photocuring initiator is less than 0.5% by weight, the polymerization reaction does not proceed uniformly at the time of light irradiation, or the curing is insufficient, so that the produced polymer (elastomer) exhibits thermal responsiveness. It becomes difficult to do. When the compounding amount of the photocuring initiator exceeds 10% by weight, the content of the mesogen group in the produced polymer (elastomer) decreases, so that it is difficult to exhibit liquid crystallinity. The photocuring initiator preferably has an absorption wavelength in the range of 200 to 600 nm. If the photo-curing initiator has an absorption wavelength in the above range, the photo-curing initiator can be used even if the liquid crystal elastomer or the liquid crystal elastomer raw material composition has low transparency (visible light transmittance). And the photocrosslinking reaction can proceed reliably.

(Isocyanate compound)
As the isocyanate compound, for example, a diisocyanate compound or a trifunctional or higher functional 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-naphthalenediisocyanate 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; B hexane diisocyanate, cyclohexane diisocyanate, 4,4'-dicyclohexyl methane diisocyanate, isophorone diisocyanate, and include alicyclic diisocyanates such as norbornane diisocyanate. The above-mentioned diisocyanate compounds may be used alone or in combination of two or more. Illustrative tri- or higher functional isocyanate compounds include triphenylmethane triisocyanate, tris (isocyanatephenyl) thiophosphate, lysine ester triisocyanate, 1,3,6-hexamethylene triisocyanate, 1,6,11-undecane triisocyanate, Examples include triisocyanates such as 1,8-diisocyanate-4-isocyanatemethyloctane and bicycloheptane triisocyanate, and tetraisocyanates such as tetraisocyanate silane. The above-mentioned trifunctional or higher functional isocyanate compounds may be used alone or in combination of two or more. As the isocyanate compound, a mixture of the above-mentioned diisocyanate compound and the above-mentioned trifunctional or higher functional isocyanate compound can be used. The blending amount of the isocyanate compound is adjusted so as to be 10 to 40% by weight, preferably 15 to 30% by weight in the whole liquid crystalline elastomer raw material composition. When the compounding amount of the isocyanate compound is less than 10% by weight, it is difficult to continuously form a liquid crystalline elastomer (liquid crystalline polyurethane) because the polymerization by the urethane reaction becomes insufficient. When the compounding amount of the isocyanate compound exceeds 40% by weight, the compounding amount of the mesogen group-containing compound in the whole liquid crystal elastomer raw material composition becomes relatively small, so that the liquid crystallinity of the liquid crystal elastomer (liquid crystal polyurethane) is reduced. descend.

<Preparation of liquid crystalline polyurethane elastomer>
The liquid crystalline polyurethane elastomer is produced by irradiating light to a liquid crystalline elastomer raw material composition containing a mesogen group-containing compound, a photopolymerizable group-containing compound, a photocuring initiator, and an isocyanate compound. Specifically, the liquid crystalline elastomer raw material composition is kneaded and heated, molded into a predetermined shape using an extruder, and then irradiated with light to cause a photocrosslinking reaction between the raw materials to be cured. . The light for irradiating the liquid crystalline elastomer raw material composition is preferably ultraviolet light or visible light having a wavelength of 200 to 600 nm. In the case of such a curing method by photocrosslinking, the liquid crystalline elastomer raw material composition is kneaded and heated, then stretched and molded, and then cured by photocrosslinking in a state where the temperature is sufficiently lowered by cooling. Can be. That is, molding and photocrosslinking (curing) can be performed as separate steps. Therefore, it is possible to obtain a liquid crystalline polyurethane elastomer in which a liquid crystal phase is definitely developed in a low temperature region.

Here, when the liquid crystalline elastomer raw material composition is formed into a film having a thickness of 0.5 mm in a state before curing (that is, a state formed by an extruder before irradiating light), the following two optical It is prepared so as to satisfy the target conditions.
(1) First condition: light transmittance at a wavelength of 500 to 800 nm is 50% or more in the entire wavelength range. (2) Second condition: light transmittance at a wavelength of 380 nm is 20% or less.

  This preparation can be performed by selecting the type of each raw material contained in the liquid crystalline elastomer raw material composition, optimizing the mixing ratio of each raw material, removing bubbles in each raw material, and the like. When the liquid crystalline elastomer raw material composition is prepared and illuminated so as to satisfy the above two optical conditions, the light can sufficiently reach the inside of the raw material, so that the generated liquid crystalline elastomer is from the surface to the inside. The photocrosslinking reaction has proceeded sufficiently, and sufficient strength can be exhibited as a material. In the first condition, the difference between the maximum light transmittance and the minimum light transmittance at a wavelength of 500 to 800 nm is preferably 20% or less. In this case, the photocrosslinking reaction between the raw materials can proceed sufficiently and efficiently.

The kneading and heating of the liquid crystalline elastomer raw material composition can be performed simultaneously with molding in an extruder. First, a liquid crystalline elastomer raw material composition is charged into an extruder and sufficiently kneaded and heated. Next, the kneaded melt is extruded while being stretched in a temperature range in which liquid crystallinity is exhibited (that is, not less than the glass transition temperature ( _Tg ) and not more than the phase transition temperature ( _Ti )). At this time, the mesogen group contained in the mesogen group-containing compound moves along the stretching direction, so that a high degree of orientation can be obtained. Then, the stretched kneaded melt is formed into an appropriate shape, cooled, and irradiated with light having a wavelength of 200 to 600 nm while maintaining the stretched state. A liquid crystalline polyurethane elastomer having both liquid crystal expression and elasticity is completed. This is a continuous manufacturing method. On the other hand, the raw material of the liquid crystalline elastomer is previously kneaded and heated to form a pellet, and the pelletized raw material is formed into a predetermined shape using an extruder, and then a temperature region where liquid crystallinity is exhibited (ie, It is also possible to produce a liquid crystalline polyurethane elastomer by stretching at a glass transition temperature ( _Tg ) or higher and a phase transition temperature ( _Ti ) or lower), and irradiating with light having a wavelength of 200 to 600 nm while maintaining the stretched state. . This is a batch-type manufacturing method. In the liquid crystalline polyurethane elastomer thus produced, the mesogenic groups are oriented in the stretching direction in a low temperature region, but when heated to exceed the phase transition temperature (T _i ), the orientation of the mesogenic groups is lost (unsatisfactory). It exhibits a specific thermal responsive behavior in which it contracts in the stretching direction (as a rule), cools and falls below the phase transition temperature (T _i ), and the orientation of the mesogenic groups is restored and stretched in the stretching direction.

Incidentally, the orientation of the liquid crystalline polyurethane elastomer can be evaluated by the degree of orientation of the mesogenic groups. In those having a large value of the degree of orientation, the mesogenic groups are highly oriented in the uniaxial direction. The degree of orientation was determined by a single total reflection measurement method (ATR) using a Fourier transform infrared spectrophotometer (FT-IR), by measuring the absorbance (0 °, 90 °) of the antisymmetric stretching vibration of aromatic ether, and methyl The absorbance (0 °, 90 °) of the symmetric bending vibration of the group is measured, and calculated based on the following formula using these absorbances as parameters.
Degree of orientation = (AB) / (A + 2B)
A: Absorbance of inverse symmetric stretching vibration of aromatic ether measured at 0 ° / Absorbance of symmetric bending vibration of methyl group measured at 0 ° B: Reverse of aromatic ether measured at 90 ° Absorbance of symmetric stretching vibration / absorption of methyl group when measured at 90 °

  In order for the liquid crystalline polyurethane elastomer to exhibit significant elasticity, the degree of orientation of the mesogenic group is preferably 0.05 or more, and more preferably 0.1 or more.

  A liquid crystalline elastomer raw material composition 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 magnification. That is, the unit of the compounding amount of each raw material can be read as “parts by weight”.

[Example 1]
In a reaction vessel, as a mesogen group-containing compound having an active hydrogen group, BH6 (500 g) in which R ₁ of the formula (1) is a single bond, potassium hydroxide (19 g), and N, N-dimethylformamide (3000 ml) as a solvent Was added and mixed, and 2 equivalents of propylene oxide as an alkylene oxide were added to 1 mol of BH6, and the mixture was reacted at 120 ° C. for 2 hours under pressure (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 distilled under reduced pressure. To obtain mesogendiol A. The synthesis scheme of mesogendiol A is shown in formula (2). The mesogen diol A shown in the formula (2) is a typical one, and may include various structural isomers.

  Next, mesogendiol A (100 g), propylene glycol diglycidyl ether acrylate adduct (4 g) and 2-hydroxyethyl acrylate (1.5 g) as photopolymerizable group-containing compounds, and 2,4,4 as photocuring initiators. 6-Trimethylbenzoyl-diphenyl-phosphine oxide (3 g) and 1,6-hexamethylene diisocyanate (38 g) as an isocyanate compound were mixed to prepare a liquid crystalline elastomer raw material composition. Then, this liquid crystalline elastomer raw material composition was heated to 100 ° C. while stirring, and cured for 2 hours to obtain a sample. Next, this sample was sandwiched between two stainless steel plates preheated to 120 ° C. via a release film, and subjected to a press treatment at 120 ° C. for 30 seconds by applying a pressure hot press of 20 MPa. After the press treatment, the stainless steel plate was removed from the sample, and the sample was cooled to room temperature while sandwiched between release films. Finally, the release film was peeled off from the sample to obtain a sample of Example 1 (a liquid crystal polyurethane elastomer precursor before photocrosslinking) having a thickness of 0.5 mm.

[Example 2]
In preparing the liquid crystalline elastomer raw material composition, propylene glycol diglycidyl ether acrylate (1 g) and 2-hydroxyethyl acrylate (3 g) were used as the photopolymerizable group-containing compound, and 1,6-hexamethylene was used as the isocyanate compound. Diisocyanate (37 g) was compounded. The other raw materials, compounding amounts, and manufacturing conditions were the same as in Example 1, and a sample of Example 2 (a liquid crystal polyurethane elastomer precursor before photocrosslinking) was obtained.

[Example 3]
In preparing the liquid crystalline elastomer raw material composition, propylene glycol diglycidyl ether acrylate adduct (7 g) and 2-hydroxyethyl acrylate (2.5 g) were used as the photopolymerizable group-containing compound, and bis (2 , 4,6-trimethylbenzoyl) -phenylphosphon oxide (3 g) and 1,6-hexamethylene diisocyanate (40 g) as an isocyanate compound. The other raw materials, the compounding amounts, and the manufacturing conditions were the same as in Example 1, and a sample of Example 3 (a liquid crystal polyurethane elastomer precursor before photocrosslinking) was obtained.

[Example 4]
In preparing the liquid crystalline elastomer raw material composition, propylene glycol diglycidyl ether acrylate adduct (6 g) and 2-hydroxyethyl acrylate (3 g) as the photopolymerizable group-containing compound, and 1-hydroxy-cyclohexyl as the photocuring initiator. -Phenyl-ketone (3 g) and 1,6-hexamethylene diisocyanate (39 g) as an isocyanate compound were blended. The other raw materials, the compounding amounts, and the manufacturing conditions were the same as in Example 1, and a sample of Example 4 (a liquid crystal polyurethane elastomer precursor before photocrosslinking) was obtained.

[Example 5]
In a reaction vessel, as a mesogen group-containing compound having an active hydrogen group, BH6 (500 g) in which R ₁ of the formula (1) is a single bond, potassium hydroxide (19 g), and N, N-dimethylformamide (3000 ml) as a solvent And 7 parts by weight of propylene oxide is added as an alkylene oxide to 2 moles of BH6 (that is, 3.5 equivalents to 1 mole of BH6). At 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 distilled under reduced pressure. To obtain mesogendiol B. Formula (3) shows a synthesis scheme of mesogendiol B. The mesogen diol B shown in the formula (3) is a representative one, and may include various structural isomers.

  Next, mesogendiol B (100 g), propylene glycol diglycidyl ether acrylate adduct (6 g) and 2-hydroxyethyl acrylate (2 g) as photopolymerizable group-containing compounds, and 2,4,6- Trimethylbenzoyl-diphenyl-phosphine oxide (1 g) and 1,6-hexamethylene diisocyanate (32 g) as an isocyanate compound were mixed to prepare a liquid crystalline elastomer raw material composition. Then, this liquid crystalline elastomer raw material composition was heated to 100 ° C. while stirring, and cured for 2 hours to obtain a sample. Next, this sample was sandwiched between two stainless steel plates preheated to 120 ° C. via a release film, and subjected to a press treatment at 120 ° C. for 30 seconds by applying a pressure hot press of 20 MPa. After the press treatment, the stainless steel plate was removed from the sample, and the sample was cooled to room temperature while sandwiched between release films. Finally, the release film was peeled off from the sample to obtain a sample of Example 5 (a liquid crystal polyurethane elastomer precursor before photocrosslinking) having a thickness of 0.5 mm.

[Comparative Example 1]
In preparing the liquid crystal elastomer raw material composition, propylene glycol diglycidyl ether acrylate (1 g) and 2-hydroxyethyl acrylate (2 g) were used as the photopolymerizable group-containing compound, and 1,6-hexamethylene was used as the isocyanate compound. Diisocyanate (37 g) was compounded. However, no photocuring initiator was used. The other raw materials, the compounding amounts, and the manufacturing conditions were the same as in Example 1, and a sample of Comparative Example 1 (a liquid crystal polyurethane elastomer precursor before photocrosslinking) was obtained.

[Comparative Example 2]
In preparing the liquid crystal elastomer raw material composition, propylene glycol diglycidyl ether acrylate (1 g) and 2-hydroxyethyl acrylate (4 g) were used as the photopolymerizable group-containing compound, and 1,6-hexamethylene was used as the isocyanate compound. Diisocyanate (27 g) was compounded. The other raw materials and compounding amounts, and the manufacturing conditions were the same as in Example 1, and a sample of Comparative Example 2 (a liquid crystal polyurethane elastomer precursor before photocrosslinking) was obtained.

(Characteristic evaluation of liquid crystalline elastomer raw material composition)
With respect to the samples of Examples 1 to 5 and Comparative Examples 1 and 2 (liquid crystalline polyurethane elastomer precursor before photocrosslinking), the light transmittance at wavelengths of 500 to 800 nm and 380 nm was measured. In addition, the samples of Examples 1 to 5 and Comparative Examples 1 and 2 (the liquid crystalline polyurethane elastomer precursor before photocrosslinking) were irradiated with UV, and the cured state (degree of photocrosslinking) of the generated liquid crystalline polyurethane elastomer was determined. evaluated. Further, the presence or absence of thermal responsiveness of the liquid crystalline polyurethane elastomer produced by photocrosslinking was confirmed. The measurement method and measurement conditions of each measurement item will be described below.

<Light transmittance>
The samples (thickness 0.5 mm) formed in Examples 1 to 5 and Comparative Examples 1 and 2 were cut into 10 mm x 50 mm, and used as light transmittance measurement samples. A sample for light transmittance measurement was put in a glass cell (optical path length 10 mm × optical path width 10 mm × height 45 mm) and filled with ultrapure water, and an ultraviolet-visible spectrophotometer (product name: UV-1600PC, manufactured by Shimadzu Corporation) was used. It measured using.

<Curing state>
Samples (thickness 0.5 mm) formed in Examples 1 to 5 and Comparative Examples 1 and 2 were cut out to 10 mm × 10 mm, and a tabletop UV curing device (product name: Eye mini-grantage (ESC-1511U), eye (Manufactured by Graphics Co., Ltd.) and UV irradiation was performed so that the irradiation energy was 500 mJ. The evaluation of the cured state was performed by measuring the gel fraction. The gel fraction was calculated from the weight before and after immersion by immersing the sample after UV irradiation in N, N-dimethylformamide (DMF) to elute the non-gelled product, and drying the sample taken out of DMF sufficiently. Those having a gel fraction of 80% or more were judged as “cured (（)”.

<Thermal response>
Samples (thickness 0.5 mm) formed in Examples 1 to 5 and Comparative Examples 1 and 2 were cut into 10 mm × 50 mm and irradiated with UV so that the irradiation energy was 500 mJ in a state of being stretched in the longitudinal direction. As a result, a liquid crystalline polyurethane elastomer was produced. Then, the length in the orientation direction (stretching direction) was measured on a scale, and those having a decrease (shrinkage) in length associated with the phase transition from the liquid crystal phase to the isotropic phase were evaluated as "heat responsive (○ ) ".

  Table 1 below summarizes the measurement results in Examples 1 to 5 and Comparative Examples 1 and 2.

  In each of the liquid crystalline elastomer raw material compositions of Examples 1 to 5, the light transmittance at a wavelength of 500 to 800 nm was 50% or more in the entire wavelength range, and the light transmittance at a wavelength of 380 nm was 20% or less. . That is, the first condition and the second condition described in the item of "Preparation of liquid crystalline polyurethane elastomer" were satisfied. It was confirmed that the liquid crystalline polyurethane elastomer produced by irradiating the liquid crystalline elastomer raw material compositions of Examples 1 to 5 with UV irradiation had a good cured state. In addition, the gel fraction was as high as 80% or more, and it is considered that the photocrosslinking proceeded sufficiently. Furthermore, the thermal responsiveness of the liquid crystalline polyurethane elastomer was confirmed, suggesting that it is useful as a thermal responsive material.

  On the other hand, in the liquid crystalline elastomer raw material composition of Comparative Example 1, the light transmittance at a wavelength of 500 to 800 nm was 50% or more in the entire wavelength range, but the light transmittance at a wavelength of 380 nm exceeded 20%. Did not meet the second condition. The liquid crystalline elastomer raw material composition of Comparative Example 1 was irradiated with UV to produce a liquid crystalline polyurethane elastomer, but it was confirmed that the composition was not cured. In addition, the gel fraction was also low, and it is considered that the photocrosslinking did not proceed sufficiently. Furthermore, the thermal responsiveness of the liquid crystalline polyurethane elastomer could not be confirmed.

  The liquid crystal elastomer raw material composition of Comparative Example 2 had a light transmittance at a wavelength of 380 nm of 20% or less, but a light transmittance at a wavelength of 500 to 800 nm of less than 50% over the entire wavelength range. Did not meet. The liquid crystalline elastomer raw material composition of Comparative Example 2 was irradiated with UV to produce a liquid crystalline polyurethane elastomer, but it was confirmed that the composition was not cured. When immersed in DMF, all were dissolved, and the gel fraction could not be measured. Furthermore, the thermal responsiveness of the liquid crystalline polyurethane elastomer could not be confirmed.

  The liquid crystal elastomer raw material composition of the present invention can be formed and cured (cross-linked) separately, and as a result, there is no danger of the raw material being cured inside the molding machine. It is a highly practical material that can handle

  The liquid crystalline elastomer raw material composition of the present invention may be applicable in the fields of clothing products (fibers), actuators, filters and the like.

Claims (3)

A mesogen group-containing compound having an active hydrogen group, a photopolymerizable group-containing compound, a photocuring initiator, and a liquid crystal elastomer raw material composition including an isocyanate compound ,
The mesogen group-containing compound having an active hydrogen group is represented by the following general formula (1):

(Where X is an active hydrogen group, R ₁ is a single bond forming part of an adjacent bonding group, -N = N-, -CO-, -CO-O-, or -CH = N- R ₂ is a single bond forming a part of an adjacent bonding group or —O—, and R ₃ is a single bond forming a part of an adjacent bonding group or an alkylene group having 1 to 20 carbon atoms. Provided that R ₂ is —O— and R ₃ is a single bond that forms part of an adjacent bonding group.)
Is a compound represented by
A liquid crystalline elastomer raw material composition having a light transmittance at a wavelength of 500 to 800 nm of 50% or more over the entire wavelength range and a light transmittance at a wavelength of 380 nm of 20% or less when deposited to a thickness of 0.5 mm.   2. The liquid crystalline elastomer raw material composition according to claim 1, wherein a difference between a maximum light transmittance and a minimum light transmittance in the light transmittance at the wavelength of 500 to 800 nm is 20% or less.   3. The liquid crystalline elastomer raw material composition according to claim 1, wherein the photocuring initiator has an absorption wavelength of 200 to 600 nm. 4.