JPWO2018096725A1 - Photocrosslinkable liquid crystalline polymer - Google Patents

Abstract

It provides a low viscosity liquid crystalline polymer produced by separating molding and curing (crosslinking). A photocrosslinkable liquid crystalline polymer comprising a site cured by photocrosslinking, which is the following test: (1) preparing two test strips of width 15 to 20 mm and length 100 mm; (2) one of the test strips Is attached to the surface of a flat plate made of aluminum and the other test piece is attached to the circumferential surface of an aluminum disc (diameter 50 mm, thickness 14 mm); (3) the circumferential face of the disc is directed to the surface of the flat plate Measure with a load of 100 g and bring the two test pieces into close contact with each other; (4) pull up the disc at a speed of 3000 mm / min and read the force when the disc leaves the plate as a tack value Photocrosslinkable liquid crystalline polymer having a tack value of 0.3 kg or less.

Description

  The present invention relates to a photocrosslinkable liquid crystalline polymer.

  The 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 use liquid crystalline polymers as elastomers in various applications.

  For example, as a liquid crystalline polymer, there is a liquid crystalline polyurethane elastomer obtained by the reaction of 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 is developed by the present applicant and has rubber elasticity in a liquid crystal development temperature region. The liquid crystalline polyurethane elastomer has a liquid crystal developing temperature lower than that of a conventional liquid crystalline polyurethane.

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 a liquid crystal development temperature range (liquid crystal phase). Further, in order to make the liquid crystalline polymer easy to be industrially used, it is required to be able to be processed into various shapes while maintaining the liquid crystal phase.

  In this regard, as described above, the liquid crystalline polymer of Patent Document 1 is designed to lower the liquid crystal expression temperature, and as a means therefor, while using trifunctional or higher 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. Thus, by using a raw material containing a large amount of crosslinkable functional groups, a crosslinking reaction proceeds between the raw materials while maintaining the liquid crystal phase during thermoforming processing, and a liquid crystalline polymer (a liquid crystalline elastomer having rubber elasticity) ) Can be obtained.

  However, in the method of causing the crosslinking reaction to proceed during thermoforming (that is, the heat curing method), the melt viscosity of the polymer increases with the progress of crosslinking, so the adhesiveness of the generated liquid crystalline polymer is increased, and the liquid crystallinity is enhanced. When the polymers adhere to each other, there is a problem that the handling becomes difficult due to the adhesion. For this reason, when industrially producing a liquid crystalline polymer, there is a need for improvement measures such that the tackiness of the polymer itself does not prevent continuous production.

  Therefore, the present inventors conducted various studies from the viewpoint of tack value, which is an index of adhesiveness, in order to improve the above-mentioned concerns observed in the liquid crystalline polymer by the conventional thermosetting method. Although the liquid crystalline polymer of Patent Document 1 described above simultaneously performs molding and curing (crosslinking) of the raw material inside the molding machine, if molding and curing (crosslinking) can be performed separately, Since the increase in melt viscosity of the polymer inside is suppressed and the tackiness of the liquid crystalline polymer is not increased, it is considered that it can cope with industrial continuous production.

  An object of the present invention is to provide a low viscosity liquid crystalline polymer produced by separating molding and curing (crosslinking).

The characteristic constitution of the photocrosslinkable liquid crystalline polymer according to the present invention for solving the above problems is as follows:
A photocrosslinkable liquid crystalline polymer comprising a site cured by photocrosslinking,
The following tests:
(1) Prepare two test strips 15-20 mm wide and 100 mm long;
(2) While sticking one test piece on the surface of a flat plate made of aluminum, the other test piece is put on the circumferential surface of an aluminum disc (diameter 50 mm, thickness 14 mm);
(3) pressing the peripheral surface of the disk toward the surface of the flat plate with a load of 100 g to bring the two test pieces into close contact with each other;
(4) The disk is pulled up at a speed of 3000 mm / min, and the force when the disk is separated from the flat plate is read as a tack value;
The above-mentioned tack value measured when carrying out is 0.3 kg or less.

The present inventors examined a photocrosslinkable (photocurable) liquid crystalline polymer as a new liquid crystalline polymer produced without using a thermosetting method. If it is a photocrosslinkable liquid crystalline polymer, molding of the raw material and photocrosslinking (curing) can be carried out as separate steps, so the increase in the melt viscosity of the polymer inside the molding machine is suppressed and as a result, it is generated An increase in the tackiness of the liquid crystalline polymer is prevented.
Here, in order to make the liquid crystalline polymer easy to handle and to be industrially producible, it is necessary to adjust the tackiness of the polymer to an appropriate range. Therefore, in the photocrosslinkable liquid crystalline polymer of the present configuration, the tack value, which is an index of adhesiveness, was set to 0.3 kg or less. In this case, since the photocrosslinkable liquid crystalline polymer of the present constitution maintains low adhesiveness, for example, after processing the polymer into a sheet or fiber and winding it into a roll, it is again obtained from the roll Even if it is pulled out, the polymers do not adhere to each other, which makes handling easy. In addition, since it is possible to cure the raw material in a state where the temperature after molding is sufficiently lowered (that is, a state in which the liquid crystal phase is expressed), the formation of monodomain becomes easy, and the generated photocrosslinkable liquid crystalline polymer The development temperature region of the liquid crystal phase is a relatively low temperature region including normal temperature. The photocrosslinkable liquid crystalline polymer having such a low-temperature liquid crystalline property can be suitably used as, for example, 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,
It is preferable that the gel fraction which is a ratio of the site | part hardened | cured by the said photocrosslinking is 80% or more.

  According to the photocrosslinkable liquid crystalline polymer of the present configuration, by setting the gel fraction to 80% or more, the portion cured by photocrosslinking in the polymer occupies most of the polymer, thereby enhancing the strength of the polymer. It can stand up to work such as winding and pulling out.

In the liquid crystalline elastomer raw material composition according to the present invention,
It is preferable that the reaction product of the mesogen group containing compound which has an active hydrogen group, an isocyanate compound, a photopolymerizable group containing compound, and a photocuring initiator is included.

  According to the photocrosslinkable liquid crystalline polymer of this configuration, a liquid crystalline polymer is obtained by reacting a mesogen group-containing compound having an active hydrogen group, an isocyanate compound, a photopolymerizable group-containing compound, and a photocuring initiator As a liquid crystal polyurethane having a wide range of application 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):

(Here, X is an active hydrogen group, R ₁ is a single bond forming a part of the adjacent bonding group, -N = N-, -CO-, -CO-O-, or -CH = N- And R ₂ is a single bond forming part of an adjacent bonding group, or -O-, and R ₃ is a single bond forming an area of the adjacent bonding group, or an alkylene group having 1 to 20 carbon atoms With the exception of those in which R ₂ is —O— and R ₃ is a single bond forming part of the adjacent linking group).
It is preferable that it is a compound represented by these.

  According to the photocrosslinkable liquid crystalline polymer of the present configuration, the compound having the above-mentioned appropriate structure is used as the mesogen group-containing compound having an active hydrogen group, and therefore, the practicability having liquid crystallinity in a low temperature range including normal temperature Photocrosslinkable liquid crystalline polymers can be produced.

In the liquid crystalline elastomer raw material composition according to the present invention,
The photopolymerizable group-containing compound is preferably 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.

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

In the liquid crystalline elastomer raw material composition according to the present invention,
It is preferable to contain 1 to 10 weight% of the said photocuring initiator.

  According to the photocrosslinkable liquid crystalline polymer of this constitution, by containing 1 to 10% by weight of a photocuring initiator, a photocrosslinkable liquid crystalline polymer excellent in the balance between low temperature liquid crystal expression and rubber elasticity is produced. be able to.

In the liquid crystalline elastomer raw material composition according to the present invention,
It is preferable to be comprised in fibrous or sheet form.

  According to the photocrosslinkable liquid crystalline polymer of this constitution, even when it is constituted in the form of a fiber or sheet, the adhesiveness between the polymers is low, and therefore, when industrial production is carried out, the polymer in the form of a fiber or sheet Can be wound or stacked, making it easy to handle.

  Hereinafter, the photocrosslinkable liquid crystalline polymer 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.

<Photo-crosslinkable liquid crystalline polymer>
The photocrosslinkable liquid crystalline polymer of the present invention is a mesogen group-containing compound having an active hydrogen group (hereinafter simply referred to as "mesogen group-containing compound"), an isocyanate compound, a photopolymerizable group-containing compound, and a photocuring initiator As a raw material, and a liquid crystalline polyurethane elastomer obtained by reacting these four raw materials. The photocrosslinkable liquid crystalline polymer (liquid crystalline polyurethane elastomer) according to the present invention has elasticity caused by the reaction between the liquid crystallinity generated from the mesogen group-containing compound and the mesogen group-containing compound and the isocyanate compound and the photopolymerizable group-containing compound. The physical properties of the liquid crystal change due to the phase transition of the liquid crystal, and the liquid crystal phase development temperature region is a relatively low temperature region including normal temperature. The liquid crystalline polymer having such a low temperature liquid crystal exhibiting property exhibits a specific behavior in which the physical properties change due to the phase transition of the liquid crystal, and for example, the phase transition between the liquid crystal phase and the isotropic phase is utilized. 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 mesogen group-containing compound, the isocyanate compound, the photopolymerizable group-containing compound, and the photocuring initiator which are the raw materials thereof will be described. .

[Mesogenic group-containing compound]
As the mesogen 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 a part of an adjacent bonding group, -N = N-, -CO-, -CO-O-, or -CH = N-, R ₂ is a single bond forming part of an adjacent bonding group, or -O-, R ₃ is a single bond forming a part of the adjacent bonding group, or an alkylene having 1 to 20 carbon atoms It is a group. Provided that R ₂ is —O— and R ₃ is a single bond forming part of an adjacent linking group. Note that “a single bond forming a part of an 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 forming part of the coupling group adjacent, R ₁ is a single bond in a state of being shared with both sides of the benzene ring, of the sides benzene Form a biphenyl structure with the ring. Examples of X include OH, SH, NH ₂ , COOH, secondary amines and the like. The compounding amount of the mesogen group-containing compound is adjusted to be 30 to 80% by weight, preferably 40 to 70% by weight, based on the whole raw material of the photocrosslinkable liquid crystalline polymer. When the blending amount of the mesogen group-containing compound is less than 30% by weight, it is difficult for the produced polymer 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 form the polymer in a low temperature range including normal temperature.

  It is preferable to use an alkylene oxide and / or a styrene oxide together with the mesogen group-containing compound. Since the alkylene oxide and / or styrene oxide function to lower the liquid crystal development temperature in the photocrosslinkable liquid crystalline polymer, the photocrosslinkability formed by using the mesogen group-containing compound in combination with the alkylene oxide and / or styrene oxide The liquid crystalline polymer can be a product excellent in practicability 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. The 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-mentioned alkylene oxide and the above-mentioned styrene oxide. The compounding amount of the alkylene oxide and / or styrene oxide is adjusted such that 1 to 10 moles, preferably 2 to 6 moles of the alkylene oxide and / or styrene oxide are added to 1 mole of the mesogen group-containing compound. When the addition mole number of the alkylene oxide and / or styrene oxide is less than 1 mole, it becomes difficult to sufficiently reduce the temperature range in which the liquid crystallinity of the photocrosslinkable liquid crystalline polymer is developed, and therefore it is solventless and liquid crystalline It becomes difficult to continuously mold a liquid crystalline polymer (liquid crystalline polyurethane) in a state in which When the addition mole number of the alkylene oxide and / or the styrene oxide exceeds 10 moles, the liquid crystallinity of the photocrosslinkable liquid crystalline polymer may become difficult to express.

[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, 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, and 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. Examples of trifunctional or higher isocyanate compounds include triphenylmethane triisocyanate, tris (isocyanatophenyl) thiophosphate, lysine ester triisocyanate, 1,3,6-hexamethylene triisocyanate, 1,6,11-undecanetriisocyanate, Examples thereof include triisocyanates such as 1,8-diisocyanate-4-isocyanatomethyloctane and bicycloheptane triisocyanate, and tetraisocyanates such as tetraisocyanate silane. The above trifunctional or higher functional isocyanate compounds may be used alone or in combination of two or more. As the isocyanate compound, it is also possible to use a mixture of the above-mentioned diisocyanate compound and the above-mentioned trifunctional or higher isocyanate compound. The compounding amount of the isocyanate compound is adjusted to be 10 to 40% by weight, preferably 15 to 30% by weight, based on the total weight of the photocrosslinkable liquid crystalline polymer. If the blending amount of the isocyanate compound is less than 10% by weight, the polymerization by the urethane reaction becomes insufficient, so that it becomes difficult to continuously mold the liquid crystalline polymer (liquid crystalline polyurethane). When the compounding amount of the isocyanate compound exceeds 40% by weight, the compounding amount of the mesogen group-containing compound occupies relatively to the whole raw material of the photocrosslinkable liquid crystalline polymer, so the liquid crystallinity of the liquid crystalline polymer (liquid crystalline polyurethane) Decreases.

[Photopolymerizable Group-Containing Compound]
As the photopolymerizable group-containing compound, for example, an acryloyl group-containing compound, a methacryloyl group-containing compound, or 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, glycerin diglycidyl ether acrylic acid adduct, 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-acrylo 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 methacryloyl group-containing compounds include 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxybutyl methacrylate, 2-methacryloyloxyethyl succinic acid, 2-methacryloyloxyethyl hexahydrophthalic acid, 2-methacroyl Roxyethyl acid phosphate, glycerine 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, 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 entire raw material of the photocrosslinkable liquid crystalline polymer. When the compounding amount of the photopolymerizable group-containing compound is less than 0.1% by weight, the produced polymer does not easily exhibit heat responsiveness because the raw material is not sufficiently cured even when irradiated with light. If the compounding 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 also, the produced polymer becomes difficult to exhibit heat responsiveness.

[Photo-curing initiator]
Photo-curing initiators include, for example, 1-hydroxy-cyclohexyl-phenyl-ketone, bis (2,4,6-trimethylbenzoyl) -phenylphosphone 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- [2 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 Sid 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-morpholine-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- (hydro) Nylthio) 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 photo-curing initiator is adjusted to be 0.5 to 10% by weight, preferably 1 to 8% by weight, based on the total weight of the photocrosslinkable liquid crystalline polymer. When the compounding amount of the photo-curing initiator is less than 0.5% by weight, the polymerization reaction does not proceed uniformly at the time of light irradiation, or the curing becomes insufficient, so it is difficult for the produced polymer to exhibit thermal responsiveness. . When the compounding amount of the photo-curing initiator exceeds 10% by weight, the content of the mesogen group in the produced polymer decreases, so that it becomes difficult to express liquid crystallinity. The photocuring initiator preferably has an absorption wavelength of 200 to 600 nm. If the photo-curing initiator has an absorption wavelength in the above range, the photo-curing initiator will give light even if the transparency (transmittance of visible light) of the photo-crosslinkable liquid crystalline polymer or its raw material is low. It can be absorbed and the photocrosslinking reaction can proceed reliably.

<Tack value of photocrosslinkable liquid crystalline polymer>
A photocrosslinkable liquid crystalline polymer is produced by irradiating light to a raw material containing a mesogen group-containing compound, an isocyanate compound, a photopolymerizable group-containing compound, and a photo-curing initiator. Specifically, the raw materials are kneaded and heated, formed into a predetermined shape using an extrusion molding machine, and then irradiated with light to advance the photocrosslinking reaction between the raw materials to be cured. The light irradiated to the raw material is preferably ultraviolet light or visible light having a wavelength of 200 to 600 nm. With such a photocrosslinking curing method, the raw materials can be kneaded and heated, and then stretched and molded to be cured in a state where the temperature is sufficiently lowered by cooling. That is, molding and photocrosslinking (curing) can be performed as separate steps. Accordingly, a crosslinkable liquid crystalline polymer in which a liquid crystal phase is reliably developed in a low temperature range can be obtained.

The photocrosslinkable liquid crystalline polymer of the present invention is set such that the tack value measured by the tack test is equal to or less than a predetermined value. The tack test is carried out according to the following procedure.
(1) Prepare two test pieces of width 15-20 mm and length 100 mm.
(2) While sticking one test piece on the surface of a flat plate made of aluminum, the other test piece is stuck on the peripheral surface of a disc made of aluminum (diameter 50 mm, thickness 14 mm).
(3) The peripheral surface of the disk is pressed against the surface of the flat plate with a load of 100 g to bring the two test pieces into close contact with each other.
(4) The disk is pulled up at a speed of 3000 mm / min, and the force when the disk is separated from the flat plate is read as a tack value.

  Although the above-mentioned tack test conforms to the tack test (Mitsubashi method) described in JIS T9233, some of the measurement conditions and the like are modified. In the present invention, the tack value of the photocrosslinkable liquid crystalline polymer measured by the above-mentioned tack test is set to 0.3 kg or less, preferably 0.2 kg or less. The tack value can be adjusted by selection of the type of each raw material, optimization of the blending ratio of each raw material, and the like. If the tack value is set to 0.3 kg or less, since the tackiness of the photocrosslinkable liquid crystalline polymer is maintained low, for example, the polymer is processed into a fiber or sheet, and this is wound into a roll. After that, it is difficult for the polymers to adhere to each other even if they are pulled out from the roll again, or if a fibrous or sheet-like polymer is laminated. Therefore, the photocrosslinkable liquid crystalline polymer of the present invention is easy to handle in industrial production. Moreover, in the present invention, since it is possible to cure the raw material in a state where the temperature after molding is sufficiently lowered (that is, a state in which the liquid crystal phase is expressed), monodomainization becomes easy, and the generated photocrosslinking The development temperature range of the liquid crystal phase of the crystalline liquid crystalline polymer is a relatively low temperature range including normal temperature. The photocrosslinkable liquid crystalline polymer having such a low-temperature liquid crystalline property can be suitably used as, for example, a thermoresponsive material utilizing a phase transition between a liquid crystal phase and an isotropic phase.

The kneading and heating of the raw material of the photocrosslinkable liquid crystalline polymer can be carried out simultaneously with molding in an extruder. First, the raw materials are charged into an extrusion molding machine and sufficiently kneaded and heated. Next, the kneaded melt is extruded while being drawn in a temperature range in which liquid crystallinity develops (that is, at least the glass transition temperature (T _g ) and at the phase transition temperature (T _i ) or less). At this time, since the mesogenic group contained in the mesogenic group-containing compound moves along the stretching direction, a high degree of orientation can be obtained. Then, the drawn kneaded melt is formed into an appropriate shape, cooled, and irradiated with light having a wavelength of 200 to 600 nm while keeping the drawn state, the crosslinking reaction proceeds between the raw materials while the orientation is maintained, and low temperature liquid crystal A liquid crystalline polymer having both expression and elasticity is completed. This is a continuous process. On the other hand, the raw material of the photocrosslinkable liquid crystalline polymer is previously kneaded and heated to be formed into a pellet, and the pelletized raw material is formed into a predetermined shape using an extrusion molding machine, and then the temperature at which liquid crystallinity develops A photocrosslinkable liquid crystalline polymer is produced by stretching in a region (that is, above the glass transition temperature (T _g ) and below the phase transition temperature (T _i )) and irradiating light at a wavelength of 200 to 600 nm while maintaining the stretched state. It is also possible. This is a batch-type manufacturing method. In the photocrosslinkable liquid crystalline polymer produced in this manner, the mesogenic groups are oriented in the stretching direction at a low temperature range, but when heated to exceed the phase transition temperature (T _i ), the orientation of the mesogenic groups is broken It exhibits a specific thermoresponsive behavior in which it shrinks in the drawing direction (in irregular order), cools, and falls below the phase transition temperature (T _i ) to restore the orientation of the mesogen groups and stretch in the drawing direction.

Incidentally, the orientation of the photocrosslinkable liquid crystalline polymer can be evaluated by the degree of orientation of the mesogen group. In the case where the value of the degree of orientation is large, the mesogenic groups are highly oriented uniaxially. The degree of orientation is the absorbance (0 °, 90 °) of antisymmetric stretching vibration of aromatic ether, and methyl according to single total reflection measurement (ATR) using Fourier transform infrared spectrophotometer (FT-IR), and methyl The absorbance (0 °, 90 °) of the symmetrical vibration of the group is measured, and the absorbance is calculated based on the following equation using these absorbances as parameters.
Degree of orientation = (A-B) / (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 Symmetrical Vibration of Methyl Group as Measured at 90 °

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

  In addition, the photocrosslinkable liquid crystalline polymer preferably has a gel fraction of 80% or more, which is a ratio of a site cured by photocrosslinking. By setting the gel fraction to 80% or more, the portion cured by photocrosslinking in the polymer occupies most of the polymer, so the strength of the polymer can be enhanced, and the work such as winding and drawing can be tolerated. be able to.

  The photocrosslinkable liquid crystalline polymer (liquid crystalline polyurethane elastomer) of the present invention was prepared and its characteristics were confirmed. In addition, although the unit of the compounding quantity of each raw material is made into "g" in the following Example and a comparative example, scale up is possible by this invention by arbitrary magnification. That is, the unit of the blending amount of each raw material can be read as "part by weight".

Example 1
In a reaction vessel, BH 6 (500 g) in which R _{1 in} 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 And add 5 equivalents of propylene oxide as alkylene oxide to 2 moles of BH 6 (ie, 2.5 equivalents to 1 mole of BH 6), and add these mixtures under pressurized conditions. The mixture was reacted at 120 ° C. for 2 hours (addition reaction). Next, oxalic acid (15 g) is added to the reaction vessel to stop the addition reaction, insoluble salts in the reaction solution are removed by suction filtration, and N, N-dimethylformamide in the reaction solution is distilled under reduced pressure. The resultant mixture was removed by the method to obtain mesogen diol A. The synthesis scheme of mesogen diol A is shown in Formula (2). In addition, the mesogenic diol A shown in Formula (2) is representative, and may contain various structural isomers.

  Next, mesogen diol A (100 g), 2-hydroxyethyl acrylate (2 g) as a photopolymerizable group-containing compound and propylene glycol diglycidyl ether acrylic acid adduct (1 g), 2,4,6- as a photo-curing initiator Trimethyl benzoyl-diphenyl-phosphine oxide (3 g) and 1,6-hexamethylene diisocyanate (35 g) as an isocyanate compound were mixed to prepare a raw material of a photocrosslinkable liquid crystalline polymer. The raw materials were heated and melted at 80 ° C. while stirring, and after cooling, the resin was crushed and pelletized with a plastic crusher (product name: ZI-420, manufactured by Horai Co., Ltd.). Subsequently, the resin pellet was introduced into a single-screw extruder (product name: SZW25GT-24MG-STD, manufactured by Technobel Co., Ltd.) set at 80 to 120 ° C., and molded into a resin sheet having a thickness of 1.0 mm. The resin sheet was passed through a cooling roll set at 15 ° C., cooled to a temperature equal to or higher than the glass transition temperature (Tg) and lower than or equal to a phase transition temperature (Ti), and wound by 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 table-top UV curing device (product name: Eye mini Grantage (ESC-1511U), manufactured by Eye Graphics Co., Ltd.) is placed between the cooling roll and the take-up roll, and the stretched resin sheet has a wavelength of 200- It was irradiated with light of 600 nm to obtain a photocrosslinkable (cured) photocrosslinkable liquid crystalline polymer of Example 1.

Example 2
When preparing a raw material of a photocrosslinkable liquid crystalline polymer, 2-hydroxyethyl acrylate (1.5 g) and a propylene glycol diglycidyl ether acrylic acid adduct (6 g) as a photopolymerizable group-containing compound and 1, 1 as an isocyanate compound 6-hexamethylene diisocyanate (38 g) was compounded. The other raw materials, blending amounts, and production conditions were the same as in Example 1, and a photocrosslinkable liquid crystalline polymer of Example 2 was obtained.

[Example 3]
When preparing the raw material of the photocrosslinkable liquid crystalline polymer, 2-hydroxyethyl acrylate (1 g) and propylene glycol diglycidyl ether acrylic acid adduct (3 g) as the photopolymerizable group-containing compound, and 1,6- as the isocyanate compound Hexamethylene diisocyanate (36 g) was blended. The other raw materials, blending amounts, and production conditions were the same as in Example 1, and a photocrosslinkable liquid crystalline polymer of Example 3 was obtained.

Example 4
When preparing a raw material of a 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- as an isocyanate compound Hexamethylene diisocyanate (39 g) was blended. The other raw materials, blending amounts, and production conditions were the same as in Example 1, and a photocrosslinkable liquid crystalline polymer of Example 4 was obtained.

[Example 5]
When preparing a raw material of a photocrosslinkable liquid crystalline polymer, 2-hydroxyethyl acrylate (0.5 g) and glycerin monoallyl ether (2 g) as a photopolymerizable group-containing compound, and 1,6-hexamethylene diisocyanate as an isocyanate compound (36 g) was blended. The other raw materials, blending amounts, and production conditions were the same as in Example 1 to obtain a photocrosslinkable liquid crystalline polymer of Example 5.

[Example 6]
In a reaction vessel, BH 6 (500 g) in which R _{1 in} 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 Are added and mixed, and 5 equivalents of propylene oxide as alkylene oxide with respect to 4 moles of BH 6 (ie, 1.25 equivalents with respect to 1 mole of BH 6) are added, and these mixtures are subjected to pressure conditions. The mixture was reacted at 120 ° C. for 2 hours (addition reaction). Next, oxalic acid (15 g) is added to the reaction vessel to stop the addition reaction, insoluble salts in the reaction solution are removed by suction filtration, and N, N-dimethylformamide in the reaction solution is distilled under reduced pressure. Thus, mesogen diol B was obtained. The synthesis scheme of mesogen diol B is shown in Formula (3). In addition, mesogenic diol B shown in Formula (3) is representative, and may contain various structural isomers.

  Next, mesogen diol B (100 g), 2-hydroxyethyl acrylate (1.5 g) as a photopolymerizable group-containing compound and propylene glycol diglycidyl ether acrylic acid adduct (2 g), 2,4, as a photo-curing initiator 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 of a photocrosslinkable liquid crystalline polymer. The subsequent operation and production conditions were the same as in Example 1 to obtain a photocrosslinkable (cured) photocrosslinkable liquid crystalline polymer of Example 6.

[Example 7]
In a reaction vessel, BH 6 (500 g) in which R _{1 in} 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 And add 3 equivalents of propylene oxide as alkylene oxide to 4 moles of BH 6 (ie, 0.75 equivalents to 1 mole of BH 6), and add these mixtures under pressurized conditions. The mixture was reacted at 120 ° C. for 2 hours (addition reaction). Next, oxalic acid (15 g) is added to the reaction vessel to stop the addition reaction, insoluble salts in the reaction solution are removed by suction filtration, and N, N-dimethylformamide in the reaction solution is distilled under reduced pressure. The mesogen diol C was obtained by The synthesis scheme of mesogen diol C is shown in Formula (4). In addition, mesogenic diol C shown in Formula (4) is representative, and may contain various structural isomers.

  Next, mesogen diol C (100 g), 2-hydroxyethyl acrylate (2 g) as a photopolymerizable group-containing compound and propylene glycol diglycidyl ether acrylic acid adduct (2 g), 2,4,6- as a photo-curing initiator Trimethyl benzoyl-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. The subsequent operation and production conditions were the same as in Example 1 to obtain a photocrosslinkable (cured) photocrosslinkable liquid crystalline polymer of Example 7.

Example 8
In a reaction vessel, BHBA 6 (500 g) in which R _{1 in} formula (1) is —CHCHN— 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 to 2 moles of BHBA 6 (ie, 2.5 equivalents to 1 mole of BHBA 6) was added, and these mixtures were added. The reaction was carried out at 120 ° C. for 2 hours under pressure conditions (addition reaction). Next, oxalic acid (15 g) is added to the reaction vessel to stop the addition reaction, insoluble salts in the reaction solution are removed by suction filtration, and N, N-dimethylformamide in the reaction solution is distilled under reduced pressure. The resultant mixture was removed by the method to obtain mesogen diol D. The synthesis scheme of mesogen diol D is shown in formula (5). In addition, mesogenic diol D shown in Formula (5) is representative, and may contain various structural isomers.

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

Comparative Example 1
When preparing the raw material of 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, light irradiation to the resin sheet was not performed. The other raw materials, blending amounts, and production conditions were the same as in Example 1 to obtain a liquid crystalline polymer of Comparative Example 1.

Comparative Example 2
In preparation of raw materials for liquid crystalline polymers, 2-hydroxyethyl acrylate (4 g) and propylene glycol diglycidyl ether acrylic acid adduct (16 g) as photopolymerizable group-containing compounds, and 1,6-hexamethylene diisocyanate as isocyanate compound (45 g) was blended. However, light irradiation to the resin sheet was not performed. The other raw materials, blending amounts, and production conditions were the same as in Example 1 to obtain a liquid crystalline polymer of Comparative Example 2.

[Characteristics evaluation of liquid crystalline elastomer raw material composition]
With respect to the photocrosslinkable liquid crystalline polymers of Examples 1 to 8 and the liquid crystalline polymers of Comparative Examples 1 to 2, the cured state and tack value of the liquid crystalline polymer after light irradiation were measured to evaluate tackiness. 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 are measured, and the presence or absence of thermal responsiveness It was confirmed. The measurement method and measurement conditions of each measurement item are described below.

<Cured state>
The sample (thickness 0.5 mm) formed into a film in Examples 1 to 8 and Comparative Examples 1 and 2 is cut out to 10 mm × 10 mm, and a desktop UV curing device (product name: eye mini grange (ESC-1511U), eye It was set in 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 measurement of gel fraction. The gel fraction was determined by immersing the sample after UV irradiation in N, N-dimethylformamide (DMF) to elute the non-gelled product, drying the sample taken out from DMF, and calculating the weight before and after the immersion. And what the gel fraction became 80% or more was judged to be "hardened ((circle))."

<Tack value>
The tack values of the photocrosslinkable liquid crystalline polymers of Examples 1 to 8 and the liquid crystalline polymers of Comparative Examples 1 to 2 were measured in accordance with the above-described tack test method in an atmosphere set at a temperature of 23 ° C. In the evaluation of tackiness, those having a tack value of 0.3 kg or less were judged as "no tackiness (○)", and those having a tack value exceeding 0.3 kg were judged as "tacky (x)" .

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

<Strength and heat response>
With respect to the photocrosslinkable liquid crystalline polymers of Examples 1 to 8, the size in the orientation direction in the liquid crystal phase (Ti-20 ° C.) and the isotropic phase (Ti + 20 ° C.) was measured by scale, and the expansion ratio was calculated by the following equation. . Those with a decrease (shrinkage) in length along with the phase transition from the liquid crystal phase to the isotropic phase were judged as “heat responsive” (○).
Expansion ratio (%) = (L _1- L ₂ ) / L ₂ × 100
L ₁ : Length in alignment direction of sample in liquid crystal phase (mm)
L ₂ : Length in the orientation direction of the sample in isotropic phase (mm)

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

  The photocrosslinkable liquid crystalline polymers of Examples 1 to 8 were all cured well, and the gel fraction was 80% or more. In addition, the tack value was 0.3 kg or less, and no tackiness that would cause a problem in practical use was observed. The liquid crystalline polymer after the light irradiation is a material excellent in usability because the glass transition temperature (Tg) and the phase transition temperature (Ti) exist with the normal temperature (about 20 to 30 ° C.) interposed therebetween. In addition, the expansion ratio was 9 to 85%, and the heat responsiveness of the liquid crystalline polymer was confirmed in all the examples, which suggested that it was useful as a heat responsive material.

  On the other hand, the liquid crystalline polymer of Comparative Example 1 was not sufficiently cured, and all dissolved when immersed in DMF, and the gel fraction could not be measured. In addition, the tack value was over 0.3 kg and it was difficult to handle due to its tackiness.

  The liquid crystalline polymer of Comparative Example 2 was not sufficiently cured, and the gel fraction was less than 80%. In addition, the tack value was over 0.3 kg and it was difficult to handle due to its tackiness.

  The photocrosslinkable liquid crystalline polymer of the present invention can be carried out separately from molding and curing (crosslinking), and as a result, the tack value becomes low, so that it can cope with continuous industrial production. Yes, it is a highly practical material.

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

Claims (7)

A photocrosslinkable liquid crystalline polymer comprising a site cured by photocrosslinking,
The following tests:
(1) Prepare two test strips 15-20 mm wide and 100 mm long;
(2) While sticking one test piece on the surface of a flat plate made of aluminum, the other test piece is put on the circumferential surface of an aluminum disc (diameter 50 mm, thickness 14 mm);
(3) pressing the peripheral surface of the disk toward the surface of the flat plate with a load of 100 g to bring the two test pieces into close contact with each other;
(4) The disk is pulled up at a speed of 3000 mm / min, and the force when the disk is separated from the flat plate is read as a tack value;
A photocrosslinkable liquid crystalline polymer having a tack value of 0.3 kg or less when measured when carrying out;   The photocrosslinkable liquid crystalline polymer according to claim 1, wherein the gel fraction which is the ratio of the site cured by the photocrosslinking is 80% or more.   The photocrosslinkable liquid crystalline polymer according to claim 1 or 2, comprising a reaction product of a mesogen group-containing compound having an active hydrogen group, an isocyanate compound, a photopolymerizable group-containing compound, and a photocuring initiator. The mesogen group-containing compound having an active hydrogen group is represented by the following general formula (1):

(Here, X is an active hydrogen group, R ₁ is a single bond forming a part of the adjacent bonding group, -N = N-, -CO-, -CO-O-, or -CH = N- And R ₂ is a single bond forming part of an adjacent bonding group, or -O-, and R ₃ is a single bond forming an area of the adjacent bonding group, or an alkylene group having 1 to 20 carbon atoms With the exception of those in which R ₂ is —O— and R ₃ is a single bond forming part of the adjacent linking group).
The photocrosslinkable liquid crystalline polymer according to claim 3, which is a compound represented by   The photocrosslinkable liquid crystalline polymer according to claim 3 or 4, wherein the photopolymerizable group-containing compound 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.   The photocrosslinkable liquid crystalline polymer according to any one of claims 3 to 5, wherein the photocurable initiator is contained in an amount of 1 to 10% by weight.   The photocrosslinkable liquid crystalline polymer according to any one of claims 1 to 6, which is configured in a fibrous or sheet form.