JP2011016787A - Liquid crystalline benzoxazine compound and liquid crystalline benzoxazine polymerizable composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid crystalline benzoxazine compound having liquid crystallinity and a liquid crystalline benzoxazine polymerizable composition which enables easy formation of a polymeric liquid crystal by the liquid crystalline benzoxazine compound.SOLUTION: The benzoxazine ring forms a mesogen of the liquid crystalline benzoxazine compound together with an atomic group X. In other words, part of the mesogen is constituted of the benzoxazine ring. Here, the benzoxazine ring is arranged at the end of the mesogen and the liquid crystalline benzoxazine compound has a structure having one benzoxazine ring alone in the molecular structure and furthermore has atomic groups R1 and R2 as spacers, and accordingly can be made liquid crystalline in spite of being a benzoxazine compound and thus a liquid crystalline benzoxazine compound can be provided. Furthermore, by incorporating p-toluenesulfonic acid and imidazole into the liquid crystalline benzoxazine polymerizable composition, the liquid crystal temperature range and the polymerization temperature range can be adjusted and the polymerization in a liquid crystal state can be made easy.

Description

  The present invention relates to a benzoxazine-based compound and a polymerization composition thereof, and particularly relates to a liquid-crystalline benzoxazine-based compound having liquid crystallinity and a liquid-crystalline benzoxazine-based polymerization composition containing the liquid-crystalline benzoxazine-based compound.

  The benzoxazine-based compound can be synthesized from phenols, amines, and formaldehyde. Since a wide variety of phenols and amines are widely provided, various types of benzoxazine compounds having desired characteristics can be synthesized by selecting the phenols and amines. This benzoxazine-based compound is a monomer that undergoes ring-opening polymerization by heating to produce polybenzoxazine. Here, since there are a wide variety of raw materials such as phenols and amines, the benzoxazine monomer to be produced can be designed with a high degree of freedom. Since there are a wide variety of benzoxazine-based compounds as monomers, it is possible to design the polymer to be produced with a high degree of freedom, and to realize polymers having various characteristics (manufacturing polybenzoxazine). This polybenzoxazine is regarded as a kind of phenol resin because it has a phenol structure in its molecular structure.

  On the other hand, higher functionalities (high Tg, high heat resistance, high mechanical strength, etc.) are desired for resin materials, and therefore polymer liquid crystals are being studied. Polymer liquid crystal is generally a polymer designed to exhibit liquid crystallinity by having a mesogenic group forming a rod-like or plate-like rigid structure and a spacer group imparting flexibility in the molecule. It is. In the polymer liquid crystal, molecular orientation occurs according to an external electric field, heat, molding conditions, and the like, and excellent mechanical strength and heat resistance can be realized depending on the orientation state. Furthermore, since the thermotropic type has the property of reducing the melt viscosity, it does not impair the molding processability even though the mechanical properties are improved, and in the field of molding materials, composite materials, etc. Widely used.

  Here, since the molecular motion is suppressed in the polymer liquid crystal, it is often difficult to align the alignment direction of the entire system even if an alignment method such as an electric field, a magnetic field, or a rubbing treatment used in the low molecular liquid crystal is used. . For this reason, a bulk polymerization method for low-molecular liquid crystals having a polymerization group has been proposed as a solution technique. The bulk polymerization method for low-molecular liquid crystals synthesizes polymer liquid crystal precursors (liquid crystal monomers) directly or via spacer groups into mesogenic groups that tend to develop a liquid crystal phase. This is a method for producing a polymer liquid crystal by polymerization.

  Currently known polymer liquid crystals include polyesters, polyester amides, polyazomethines (above thermotropic liquid crystals), polyamides, polybenzothiazoles (above lyotropic liquid crystals), and the like. For example, JP-A-8-509020 ( Patent Document 1) discloses a liquid crystalline polyester resin. Japanese Unexamined Patent Application Publication No. 2004-331811 (Patent Document 2) proposes a liquid crystalline epoxy resin having improved heat dissipation characteristics by introducing a mesogenic skeleton of an azomethine group into the epoxy resin. Japanese Patent Application Laid-Open No. 2004-225034 (Patent Document 3) proposes a liquid crystalline epoxy resin in which a mesogen skeleton is introduced into an epoxy resin for the purpose of improving thermal conductivity. Furthermore, Japanese Patent Laid-Open No. 9-302070 (Patent Document 4) introduces a mesogenic skeleton into a curing agent or a main epoxy resin, thereby improving the high-temperature strength, thermal strain and water absorption while providing adhesion. Liquid crystalline epoxy resins that can be suppressed have been proposed. Japanese Patent Laid-Open No. 2006-306778 (Patent Document 5) proposes a polybenzoxazine having a higher Tg and higher heat resistance than an epoxy resin, in which a mesogen skeleton is introduced into the molecule.

Japanese National Patent Publication No. 8-509020 JP 2004-331811 A JP 2004-225034 A JP-A-9-302070 JP 2006-306778 A

  However, the inventions described in Patent Documents 1 to 4 relate to a liquid crystalline polyester resin and a liquid crystalline epoxy resin, and the technology relating to a benzoxazine-based compound having a significantly different chemical structure cannot be applied. Therefore, there has been a problem that a benzoxazine-based compound of a liquid crystal monomer cannot be obtained from the disclosed technology.

  In the invention described in Patent Document 5, the cured product obtained by curing a benzoxazine-based compound into which a mesogenic group (rigid structure) is introduced has improved mechanical strength due to the effect of the mesogenic group. However, liquid crystallinity is not shown in the obtained benzoxazine-based compound and its cured product.

  In other words, even if a mesogenic group is introduced, a benzoxazine-based compound having liquid crystallinity (a benzoxazine-based compound or a liquid-crystalline benzoxazine-based compound serving as a liquid crystal monomer) is obtained due to structural factors attributable to the benzoxazine ring. There was a problem that it was difficult. As a result, in the benzoxazine-based compounds that can be designed in various ways, the liquid crystal monomer is not yet provided.

  Furthermore, even if a liquid crystalline benzoxazine-based compound is created, it is sufficient that the resulting benzoxazine-based resin does not become a polymer liquid crystal simply by heating and polymerizing the liquid crystalline benzoxazine-based compound. Assumed. For example, when the liquid crystal temperature range of the created liquid crystalline benzoxazine compound appears at a lower temperature than the polymerization temperature of the benzoxazine compound, it is important to design a polymerization system that can adjust the liquid crystal temperature range and the polymerization temperature. . However, in the current situation where it is difficult to create a liquid crystalline benzoxazine-based compound, it becomes more difficult to design a polymerization system (liquid crystalline benzoxazine-based polymerization composition) for facilitating the production of the polymer liquid crystal. There was a problem that.

  The present invention has been made to solve the above-mentioned problems, and a liquid crystalline benzoxazine compound having liquid crystallinity and a liquid crystalline benzoxazine that facilitates the formation of a polymer liquid crystal using the liquid crystalline benzoxazine compound. It aims at providing a system polymerization composition.

  In order to achieve the above object, the liquid crystalline benzoxazine-based compound according to claim 1 is a benzoxazine-based compound that has a high molecular weight by a polymerization reaction, and has a benzoxazine ring and a plurality of benzene rings, and The plurality of benzene rings are connected to each other directly or indirectly so that the plurality of benzene rings are arranged along one direction, and the benzene ring at one of the connecting ends is connected to the benzene ring of the benzoxazine ring. Bonded to the first atomic group directly or indirectly linked to at least one of the benzene ring at the other linking end of the plurality of benzene rings or the hetero ring of the benzoxazine ring in the first atomic group And a second atomic group that imparts flexibility to the molecule, and is formed in an asymmetric structure in which one benzoxazine ring is included in the molecular structure It is those having liquid crystallinity.

  The term “high molecular weight by polymerization reaction” means that the molecular weight is increased by the reaction, and includes not only the high molecular weight of the monomer but also the high molecular weight by network formation by a crosslinking reaction. It is.

  Moreover, the benzoxazine ring means that the skeleton is formed of a benzoxazine ring structure, and is a concept including that in which a hydrogen atom to be bonded is substituted with a substituent.

  Furthermore, arranging a plurality of benzene rings along one direction means that the plurality of benzene rings are arranged so as to extend substantially in one direction, and indicates only alignment on a straight line. is not.

  The liquid crystalline benzoxazine-based compound according to claim 2 is the liquid crystalline benzoxazine-based compound according to claim 1, wherein the first atomic group includes a functional group for bonding the plurality of benzene rings; It has a functional group for binding the benzene ring at one of the connecting ends to the benzoxazine ring.

  The liquid crystalline benzoxazine-based compound according to claim 3 is the liquid crystalline benzoxazine-based compound according to claim 2, wherein the functional group includes at least one of an imino group or an ester group.

  The liquid crystalline benzoxazine-based compound according to claim 4 is the liquid crystalline benzoxazine-based compound according to claim 2 or 3, wherein the functional group for bonding the plurality of benzene rings is bonded to the bonded benzene ring. Is located in the para position.

  The liquid crystalline benzoxazine-based compound according to claim 5 is the liquid crystalline benzoxazine-based compound according to claim 4, wherein the first atomic group is represented by the following general formula (1): It is bonded to the benzoxazine ring through a group.

  The liquid crystalline benzoxazine-based compound according to claim 6 is the liquid crystalline benzoxazine-based compound according to claim 4, wherein the first atomic group is represented by the following general formula (2): It is bonded to the benzoxazine ring through a group.

  The liquid crystalline benzoxazine-based compound according to claim 7 is the liquid crystalline benzoxazine-based compound according to any one of claims 1 to 6, wherein the second atomic group is an alkyl group or an alkoxy group.

  The liquid crystalline benzoxazine-based polymerization composition according to claim 8 is selected from the liquid crystalline benzoxazine-based compound according to any one of claims 1 to 7 and any of an inorganic acid, an inorganic base, an organic acid, and an organic base. Containing at least one additive.

  Inorganic acids, inorganic bases, organic acids, organic bases such as hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, boric acid, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, formic acid, acetic acid, citric acid, Examples include oxalic acid, p-toluenesulfonic acid, pyridine, trialkylamine, diazabicycloundecene, histidine, imidazolium compounds, and the like. These may be used alone or in combination of two or more.

  The liquid crystalline benzoxazine-based polymer composition according to claim 9 is the liquid crystal benzoxazine-based polymer composition according to claim 8, wherein the additive is p-toluenesulfonic acid or imidazole.

  According to the liquid crystalline benzoxazine-based compound according to claim 1, the first atomic group includes the plurality of benzene rings directly or indirectly such that the plurality of benzene rings are arranged along one direction. Are interconnected. In general, a molecular structure having linearity and planarity tends to be a rigid molecular structure, but a benzene ring connection structure can realize a rigid molecular structure having such linearity and planarity. Furthermore, the present compound has a second atomic group that imparts flexibility to the molecule.

  Here, in general, it is an important requirement to develop liquid crystallinity to provide both a site for imparting rigidity and a site for imparting flexibility, but a benzoxazine system having a benzoxazine ring. A compound does not easily become liquid crystalline simply by introducing an atomic group that is supposed to form a site imparting rigidity and an atomic group that forms a site imparting flexibility into the molecule.

  However, this compound comprises the first atomic group and the second atomic group, and the benzene ring at the linking end of the first atomic group is directly or indirectly connected to the benzoxazine ring. Further, the molecular structure includes one benzoxazine ring. For this reason, even if it has a benzoxazine ring, the influence which the said benzoxazine ring has on the linearity and planarity created by the connection structure of a benzene ring can be made small. Therefore, there is an effect that a compound having liquid crystallinity, that is, a liquid crystalline benzoxazine compound can be obtained in the benzoxazine compound which has been difficult in the past.

  According to the liquid crystalline benzoxazine-based compound according to claim 2, in addition to the effect exhibited by the liquid crystalline benzoxazine-based compound according to claim 1, the first atomic group has a function for bonding a plurality of benzene rings. And a functional group for bonding the benzene ring and the benzoxazine ring at one of the connecting ends. That is, the plurality of benzene rings of the first atomic group are bonded to each other via the functional group, and the first atomic group and the benzoxazine ring are also connected to each other via the functional group. Therefore, there is an effect that the present compound can be easily synthesized using a derivative having a functional group. In addition, since the polarization is increased by having a functional group, there is an effect that even a benzoxazine-based compound can be more easily liquid crystalline.

  According to the liquid crystalline benzoxazine-based compound according to claim 3, in addition to the effect exhibited by the liquid crystalline benzoxazine-based compound according to claim 2, the functional group includes at least one of an imino group or an ester group. Here, since the imino group or the ester group has a large polarization among the functional groups, even if it is a benzoxazine-based compound, there is an effect that the liquid crystallinity can be more easily achieved.

  According to the liquid crystalline benzoxazine-based compound according to claim 4, in addition to the effect exhibited by the liquid crystalline benzoxazine-based compound according to claim 2 or 3, the functional group for bonding a plurality of benzene rings is a benzene ring. Since it is located in the para-position via, the linearity of the first atomic group can be improved, and a liquid crystalline benzoxazine-based compound can be created more easily. There is.

  According to the liquid crystalline benzoxazine-based compound according to claims 5 and 6, in addition to the effect exhibited by the liquid crystalline benzoxazine-based compound according to claim 4, the liquid crystalline property can be easily expressed. effective.

  According to the liquid crystalline benzoxazine-based compound according to claim 7, in addition to the effect exhibited by the liquid crystalline benzoxazine-based compound according to any one of claims 1 to 6, the second atomic group is an alkyl group or an alkoxy group. Therefore, there is an effect of effectively contributing to the development of thermotropic liquid crystal properties.

  According to the liquid crystalline benzoxazine-based polymerization composition according to claim 8, the liquid crystalline benzoxazine-based compound according to any one of claims 1 to 7, and any one of an inorganic acid, an inorganic base, an organic acid, and an organic base Therefore, there is an effect that the ring-opening polymerization temperature of benzoxazine can be changed as compared with the case where the additive is not blended. Furthermore, there is an effect that the liquid crystal temperature range in which the liquid crystalline benzoxazine-based compound is in a liquid crystal state can be changed. For this reason, when there is a difference between the liquid crystal temperature range of the liquid crystalline benzoxazine-based compound and the polymerization temperature range, both temperature ranges can be adjusted, and polymerization in a liquid crystal state can be facilitated.

  According to the liquid crystalline benzoxazine-based polymer composition according to claim 9, in addition to the effect exhibited by the liquid crystal benzoxazine-based polymer composition according to claim 8, the additive is p-toluenesulfonic acid or imidazole. There is an effect that the polymerization reaction can be performed satisfactorily. Moreover, the upper limit temperature of a liquid-crystal temperature range can be raised by mix | blending p-toluenesulfonic acid or imidazole.

  In general, a benzoxazine compound is polymerized by heating to 200 ° C. to 230 ° C. When the liquid crystal temperature range of the liquid crystalline benzoxazine compound is lower than this, p-toluenesulfonic acid or imidazole is added. By blending, the upper limit temperature of the liquid crystal temperature range can be increased and polymerization in the liquid crystal state can be facilitated.

  Furthermore, when the additive is p-toluenesulfonic acid, the liquid crystal temperature range of the liquid crystalline benzoxazine-based compound can be expanded. Here, the polymerization temperature of the liquid crystalline benzoxazine-based compound can be adjusted by adding a catalyst or copolymerizing with other copolymerization components other than the benzoxazine-based compound. In this case, the narrower the liquid crystal temperature range is, the more severe the adjustment of the polymerization temperature is required, and the higher the adjustment is, the more labor is required. However, according to the present composition containing p-toluenesulfonic acid, the liquid crystal temperature range of the liquid crystalline benzoxazine-based compound can be expanded, so that the temperature range in which polymerization can proceed in the liquid crystal state can be expanded. Polymerization within the temperature range can be facilitated.

It is the figure which showed the 1H NMR spectrum of the raw material phenol produced | generated in Example 1 of this invention. It is the figure which showed the 1H NMR spectrum of the liquid crystalline benzoxazine type compound 3 produced | generated in Example 3 of this invention. It is the figure which showed the 1H NMR spectrum of the raw material phenol (azomethine phenol) produced | generated in Example 4 of this invention. It is the figure which showed the 1H NMR spectrum of the liquid crystalline benzoxazine type compound 4 produced | generated in Example 4 of this invention. 2 is a diagram showing a 1H NMR spectrum of benzoxazine-based compound 1 produced in Comparative Example 1. FIG. 6 is a diagram showing a 1H NMR spectrum of benzoxazine-based compound 2 produced in Comparative Example 2. FIG. 4 is a diagram showing a 1H NMR spectrum of a benzoxazine-based compound 4 produced in Comparative Example 3. FIG. 6 is a diagram showing a 1H NMR spectrum of benzoxazine-based compound 5 produced in Comparative Example 4. FIG. 6 is a diagram showing a 1H NMR spectrum of an aldehyde group-containing benzoxazine produced in Comparative Example 5. FIG. 6 is a diagram showing a 1H NMR spectrum of a benzoxazine-based compound 6 produced in Comparative Example 5. FIG.

  Hereinafter, the present invention will be described in detail. The liquid crystalline benzoxazine-based compound of the present invention is a compound represented by the following general formula (3) having a benzoxazine ring structure that can be synthesized from phenols, amines, and formaldehyde. In general formula (3), X (hereinafter referred to as atomic group X) and R1 (hereinafter referred to as atomic group R1) are atomic groups bonded to the benzoxazine ring, and atomic group X forms a hard segment. It becomes a mesogen together with the benzoxazine ring. The atomic group R1 is a bent chain serving as a spacer. Further, R2 bonded to the atomic group X (hereinafter referred to as the atomic group R2) is also a bent chain serving as a spacer. In the general formula (3), the atomic group X represented by X corresponds to the first atomic group described in the claims, and the atomic groups represented by R1 and R2 (the atomic group R1 and the atomic group R2) are defined in the claims. Corresponds to 2 atomic groups.

  In the present liquid crystalline benzoxazine-based compound, the atomic group X shown in the general formula (3) has a structure in which a plurality of benzene rings are connected. Each benzene ring is connected so as to form a main chain, not a branched chain, and each benzene ring of the atomic group X is arranged along one direction.

  In the present liquid crystalline benzoxazine-based compound, when a plurality of benzene rings are linked via a functional group, the functional group (linking group) is preferably a divalent functional group capable of forming a rigid bond. Examples of the divalent functional group include an ester group, a ketone group, an imino group (imine, azomethine), an azo group, and a diimide group. Preferable are an ester group and an imino group.

  In addition, the linking group that connects a plurality of benzene rings is not limited to the functional group as described above, but is a divalent organic group conjugated with the benzene ring, such as an alkene group, an alkyne group, a vinylene group, an arylene group. It may be. Further, it may be a single bond that directly bonds the benzene ring, such as biphenyl.

  It should be noted that the fact that the benzene rings are connected via a functional group in this way corresponds to the indirect connection described in the claims, and the benzene rings are connected like a biphenyl structure. Corresponds to being directly connected to each other as described in the claims.

  The atomic group X is a segment that forms a mesogen and has a structure that imparts rigidity to the molecule. The structure for imparting liquid crystallinity, generally called mesogen, is considered to be an important factor in that the molecular structure is a flat plate or linear (rod-like). ing.

  Here, if the degree of freedom of molecular movement of the linking group connecting each benzene ring is large, the planarity and linearity of the molecular structure of the atomic group used as the mesogen will be disturbed, and as a result, it is difficult to express liquid crystal It becomes. Therefore, the functional groups and alkene groups described above are selected as the linking group that binds the benzene ring in order to give the benzene ring and the linking group a tendency of multiple bonds by the resonance effect to regulate molecular motion. is there.

  Furthermore, it is desirable that the bond for connecting the benzene rings in the atomic group X is located at the para position (para position of the benzene ring) via the benzene ring. According to this, since the functional group etc. which connect a benzene ring are arrange | positioned in para position via a benzene ring, the benzene ring of the both sides with respect to one benzene ring is via a functional group etc. It will be placed in the para position. Therefore, the linearity of the molecular structure of the atomic group X is improved, and the liquid crystallinity is more easily exhibited. The atomic group X only needs to have a structure in which a plurality of benzene rings are substantially along one direction, and is not necessarily limited to a structure in which the benzene rings are arranged in the para position. For example, a structure in which a meta-oriented bond and an ortho-oriented bond are repeated may be included, and a meta-oriented or ortho-oriented bond may be partially included.

  Among the above-mentioned plurality of benzene rings forming the main chain in the atomic group X, those adjacent to the benzoxazine ring are bonded to the benzene ring of the benzoxazine ring via a linking group such as the above functional group or alkene group. Are combined. Each linking group contained in one liquid crystalline benzoxazine-based compound may be the same or different.

  The benzoxazine ring in the general formula (3) is a condensed ring of a benzene ring and a hetero ring. The hydrogen atom of this benzoxazine ring is a halogen or an alkyl group, as well as an allyl group, a hydroxy group, a thiol group, an aldehyde group, a carboxyl group, an acyl group, an amino group, a cyano group, a nitro group, a sulfo group, a phospho group, etc. May be substituted. Moreover, the hydrogen atom to be substituted may be singular or plural.

  Such a benzoxazine ring, together with the atomic group X, forms a mesogen of the present liquid crystalline benzoxazine-based compound. In other words, a part of the mesogen of the liquid crystalline benzoxazine-based compound is composed of a benzoxazine ring.

  In general, when a plurality of benzene rings are connected at the para position as in the atomic group X, a molecular structure in which each benzene ring is arranged with high linearity is easily obtained. However, the benzoxazine ring is a condensed ring of a benzene ring and a heterocycle, and when the benzene ring and the benzoxazine ring are combined to form a mesogen containing the benzoxazine ring, a bent structure is formed. That is, the linearity of the molecular structure is lowered.

  Therefore, the present liquid crystalline benzoxazine-based compound has a structure in which the benzoxazine ring is arranged at the end of the mesogen and only one benzoxazine ring is included in the molecular structure.

  For example, when a benzoxazine ring is provided at both ends of a mesogen, the linearity of the molecular structure is lower than when a benzoxazine ring is provided at one end. Molecular structures with low linearity are unlikely to be mesogens, in which case the compounds are often not liquid crystalline. Therefore, this liquid crystalline benzoxazine-based compound has a structure in which only one benzoxazine ring is introduced at the end of the mesogen, thereby maintaining the linearity of the mesogen long in the axial direction of the main chain. Even if it is contained, it suppresses a decrease in linearity of the structure portion which is a mesogen.

  As described above, the atomic group R1 in the general formula (3) is a bent chain serving as a spacer, and has a structure in which one or more carbon atoms are bonded by a single bond. The atomic group R1 is preferably linear, but may have a branched chain and may contain a hetero atom in the structure. Preferably, the atomic group R1 is composed of an alkyl group. The chain length n is in the range of 1 to 19, and preferably in the range of 1 to 7.

  In addition, as described above, the atomic group R2 in the general formula (3) is also a bent chain serving as a spacer, and is a benzene ring at the end of the atomic group X (on the opposite side of the benzene ring adjacent to the benzoxazine ring). Benzene ring at the end). The bonding position is a position that is para to the bond for bonding the benzene ring at the end to another benzene ring (the linking group such as the above-described functional group or alkene group). In other words, the atomic group R2 is a substituent substituted with the hydrogen atom at the para position of the benzene ring of the atomic group X.

  The atomic group R2 may be any group as long as it does not significantly inhibit the linearity of the atomic group X, and various monovalent substituents can be appropriately selected. Preferably, an alkyl group or an alkoxy group is used. It is because it acts advantageously on the development of thermotropic liquid crystal properties.

  Further, when the atomic group R2 is composed of an alkoxy group, the liquid crystal temperature range can be changed by changing the number of carbon atoms constituting the alkoxy group, and by appropriately selecting the number of carbon atoms, the liquid crystal temperature range Can be raised to a higher temperature side.

  For example, when a high molecular liquid crystal polybenzoxazine resin is desired, it is very important to polymerize a liquid crystalline benzoxazine compound in a liquid crystal state. However, the polymerization temperature of the liquid crystalline benzoxazine-based compound is relatively high such as 200 to 230 ° C., and the liquid crystal temperature range is often lower than the polymerization temperature. The liquid crystalline benzoxazine-based polymerization composition described below is intended to eliminate the temperature difference between the liquid crystal temperature range and the polymerization temperature by adjusting the polymerization temperature (lowering the temperature) by adding a catalyst or copolymerization. The larger the value, the higher the adjustment of the polymerization temperature. The liquid crystalline benzoxazine-based compound of the present invention can adjust the liquid crystal temperature range by slightly changing the structure of the atomic group R2 serving as a spacer. For example, the upper limit value is raised to a higher temperature side. Can be adjusted. As a result, the adjustment range of the polymerization temperature can be reduced, and the temperature difference between the liquid crystal temperature range and the polymerization temperature can be easily eliminated.

  In order to give flexibility to the molecular structure, it is not always necessary to provide both of the atomic groups R1 and R2, and it is sufficient that at least one of the atomic groups R1 and R2 is provided.

  Thus, the present liquid crystalline benzoxazine-based compound includes the mesogens and spacers configured as described above in the molecule, so that even a benzoxazine-based compound can be liquid crystalline.

  The liquid crystalline benzoxazine-based compound of the present invention may be one compound (single) having the structure of the general formula (3) or a mixture of a plurality of compounds.

  Phenols, amines, and formaldehyde that are raw materials for the liquid crystal benzoxazine-based compound described above are known substances. As a method for obtaining the product, commercially available products may be used, or the product may be obtained by producing and purifying each based on a known method.

  Phenols are raw materials for forming the atomic group X and the benzene ring of the benzoxazine ring, and various types are appropriately selected according to the molecular structure of the liquid crystalline benzoxazine compound to be obtained. For example, when a liquid crystalline benzoxazine-based compound in which the atomic group X and the benzene ring of the benzoxazine ring are linked by an azo group is desired, methoxybenzylidene hydroxyaniline (azomethine), azomethine phenol, or the like is used as the phenol. In the case where a liquid crystalline benzoxazine-based compound in which the atomic group X and the benzene ring of the benzoxazine ring are linked by an ester group is desired, phenyl 4-hydroxybenzoate can be used.

  Furthermore, if biphenols such as 4-hydroxycyanobiphenyl are used, a liquid crystalline benzoxazine-based compound in which the atomic group X and the benzene ring of the benzoxazine ring are bonded by a single bond can be constructed. In addition, when these derivatives are used, an atomic group X in which a plurality of benzene rings are connected by the above-described linking group can be easily constructed.

Furthermore, phenols with liquid crystallinity (RAVora, RSGupta, MolecularCrystals
and Liquid Crystals, 56, 31 (1979)) may be used as the raw material phenol. The phenols for producing the liquid crystalline benzoxazine-based compound are not limited to these.

  In the present invention, the amines (amines forming the atomic group R) used as a raw material for the liquid crystalline benzoxazine-based compound are appropriately selected from aliphatic amines, aromatic amines, substituted products and derivatives thereof. The Such amines may contain hetero atoms in the main chain.

  The production method of the present liquid crystalline benzoxazine-based compound is not particularly limited. For example, the above-mentioned essential components (phenols, amines, formaldehyde) and optional components (solvent, etc.) are charged into the reaction vessel at once or sequentially. Then, a method of producing by heating and refluxing can be applied.

  In addition, a benzoxazine-based compound (for example, an aldehyde group-containing benzoxazine compound produced using hydroxybenzaldehyde as a raw material) is manufactured in advance, and then the raw material (for example, phenylenediamine) is reacted to add an atomic group X. The manufacturing method can be applied.

  In the present liquid crystalline benzoxazine-based compound, the benzoxazine ring is a polymerization group, and the present liquid crystalline benzoxazine-based compound is a liquid crystal monomer that can be polymerized by opening the benzoxazine ring. For this reason, it can polymerize in a liquid crystal state to produce a polymer. When this liquid crystalline benzoxazine-based compound is polymerized by ring-opening polymerization of a benzoxazine ring, a phenol resin (polybenzoxazine) is obtained.

  The liquid crystalline benzoxazine-based compound is usually polymerized (cured) by heating at about 200 to 230 ° C. for about 10 to 180 minutes.

  In general, the polymerization of a benzoxazine-based compound can proceed by ring-opening polymerization by heating in the absence of a catalyst, so that no catalyst is required and no by-product is generated during the polymerization process. A polymer having good dimensional stability can be obtained.

  Of course, the liquid crystalline benzoxazine-based compound can be polymerized by heating in the absence of a catalyst as in the case of other benzoxazine-based compounds. However, polymerization may be performed using a generally used catalyst.

  The liquid crystalline benzoxazine-based polymerization composition of the present invention is a mixture comprising the liquid crystalline benzoxazine-based compound of the present invention and an additive, and is a composition for finally producing a polymer. In particular, when a polybenzoxazine-based resin of a polymer liquid crystal is desired, it is very important to polymerize a liquid crystalline benzoxazine-based compound in a liquid crystal state. However, the liquid crystal temperature range of the liquid crystalline benzoxazine-based compound is often lower than the polymerization temperature. Therefore, by adding an additive to the liquid crystalline benzoxazine-based compound, the liquid crystalline benzoxazine-based polymerized composition is polymerized so that the polymerization temperature is lowered and the liquid crystalline benzoxazine-based compound is polymerized while maintaining the liquid crystal state. It is designed.

  Here, the additive is an inorganic acid, an inorganic base, an organic acid, or an organic base, and preferably an additive that promotes ring-opening polymerization of benzoxazine. Examples of such additives include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, boric acid, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, formic acid, acetic acid, citric acid, oxalic acid, p-toluenesulfonic acid, Examples include benzoic acid, phenol, thiophenol, pyridine, trialkylamine, diazabicycloundecene, histidine, and imidazolium compounds. These may be used alone or in combination of two or more.

  More preferably, hydrochloric acid, p-toluenesulfonic acid (p-toluenesulfonic acid), benzoic acid, phenol, thiophenol, 2-ethyl-4-methylimidazole and the like, which are widely used as a polymerization catalyst, are used as the additive, Particularly preferably, p-toluenesulfonic acid or 2-ethyl-4-methylimidazole is used.

  The amount of the additive is appropriately selected according to the kind of the additive, but is desirably 0.001 part by weight or more and 50 parts by weight or less with respect to 100 parts by weight of the liquid crystal benzoxazine-based compound. If the blending amount of the additive is less than 0.001 part by weight, the liquid crystal temperature range cannot be expanded and the polymerization temperature cannot be lowered, and if it exceeds 50 parts by weight, macroscopic phase separation tends to occur. is there.

  Moreover, liquid crystal temperature range adjustment of a liquid crystal benzoxazine type compound can be performed, such as when an additive is p-toluenesulfonic acid or 2-ethyl-4-methylimidazole. Here, when such an additive is blended for the purpose of increasing the upper limit temperature of the liquid crystal temperature range, the blending amount is preferably 0.01 parts by weight or more and 10 parts by weight with respect to 100 parts by weight of the liquid crystal benzoxazine-based compound. Less than 0.01 parts by weight, and more preferably 0.01 parts by weight or more and 5 parts by weight or less. Within such a range, by adding the additive, the heat resistance and dielectric properties of the benzoxazine-based resin, which is the polymerization product, can be greatly increased while increasing the liquid crystal upper limit temperature, expanding the liquid crystal temperature range, and lowering the polymerization temperature. Do not decrease.

  Here, when using an additive that lowers the polymerization temperature as the blending amount increases, if the difference between the polymerization temperature and the liquid crystal temperature range is large, a large amount of additive blending is required, and the benzoxazine that becomes the polymerization product This may cause problems such as lowering the heat resistance and dielectric properties of the resin. As described above, the liquid crystalline benzoxazine-based compound can increase the upper limit of the liquid crystal temperature range by changing the molecular structure of the atomic group R2, and as a result, the adjustment range of the polymerization temperature can be narrowed. . For this reason, the compounding quantity of the additive mix | blended with liquid crystalline benzoxazine-type polymerization composition can be suppressed, and the heat resistance and dielectric property of the benzoxazine-type resin used as a polymerization product are other than benzoxazine-type resin. It is possible to avoid a situation where it is greatly reduced by other components.

  In addition, the present liquid crystalline benzoxazine-based polymerization composition may be blended not only with one kind of additive but also with a plurality of kinds of additives. Moreover, you may be comprised including components other than the additive mentioned above. Examples of such components include various fillers such as alumina, titania, and calcium carbonate, and copolymer components that copolymerize with liquid crystalline benzoxazine compounds.

  The copolymer component to be blended in the liquid crystalline benzoxazine-based polymerization composition is not particularly limited, and examples thereof include an epoxy resin, a phenol resin, a melamine resin, an unsaturated polyester resin, a polyimide resin, a polyamide resin, and a polyurethane resin. Can be mentioned. These may be used alone or in combination of two or more.

  In addition, since this liquid crystalline benzoxazine-based compound generates a hydroxy group when heated, it can be co-crosslinked with a resin having a functional group reactive with a hydroxy group such as an epoxy resin or a phenol resin. The mechanical properties of the resin can be greatly improved. In particular, an epoxy resin is more preferable because a cured product can be easily obtained.

  The epoxy resin is not particularly limited as long as it is a compound having at least one epoxy group. Specifically, for example, bisphenol A, bisphenol F, bisphenol S, hexahydrobisphenol A, tetramethylbisphenol A, pyrocatechol, resorcinol, cresol novolac, tetrabromobisphenol A, trihydroxybiphenyl, bisresorcinol, bisphenol hexafluoroacetone Glycidyl ether type obtained by reaction of polychlorophenol such as tetramethylbisphenol F, bixylenol, dihydroxynaphthalene and epichlorohydrin; glycerin, neopentyl glycol, ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, polyethylene glycol, Aliphatic polyhydric alcohols such as polypropylene glycol and epichlorohydrin Polyglycidyl ether type obtained by the reaction of glycidyl ether ester type obtained by the reaction of hydroxycarboxylic acid such as p-oxybenzoic acid and β-oxynaphthoic acid and epichlorohydrin; phthalic acid, methylphthalic acid, isophthalic acid, terephthalic acid , Tetrahydrophthalic acid, hexahydrophthalic acid, endomethylenetetrahydrophthalic acid, endomethylenehexahydrophthalic acid, trimellitic acid, polyglycidyl ester type derived from polycarboxylic acid such as polymerized fatty acid; aminophenol, aminoalkylphenol Glycidylaminoglycidyl ether type derived from glycidylaminoglycidyl ester type derived from aminobenzoic acid; aniline, toluidine, tribromoaniline, xylylenediamine Glycidylamine type derived from amine, diaminocyclohexane, bisaminomethylcyclohexane, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, etc .; epoxidized polyolefin, glycidylhydantoin, glycidylalkylhydantoin, triglycidylsia Examples include nurate. These may be used alone or in combination of two or more.

  As described above, according to the liquid crystalline benzoxazine-based compound of the present invention, liquid crystallinity can be imparted to the benzoxazine-based compound that has been difficult to impart liquid crystallinity by having the above structure. According to this, a benzoxazine-based compound can be provided as a liquid crystal monomer. In addition, a polymer having a skeleton derived from the liquid crystalline benzoxazine-based compound can be generated. Furthermore, according to the liquid crystalline benzoxazine-based polymerization composition of the present invention, the polymerization temperature of the liquid crystalline benzoxazine-based compound can be adjusted, and the liquid crystalline benzoxazine-based compound can be easily polymerized in a liquid crystal state.

  Next, the present invention will be described in more detail based on examples and comparative examples, but the present invention is not limited to these examples.

  In addition, the structure determination of the compound synthesize | combined in each Example and the comparative example and evaluation of liquid crystallinity were performed with the following analysis method.

(Structure Determination) Structure determination was performed by proton nuclear magnetic resonance (1H NMR). 1H NMR was measured at room temperature using deuterated chloroform or deuterated dimethyl sulfoxide as a measurement solvent. In FIGS. 1 to 10, the measured compounds are shown above each figure, and the 1H NMR spectrum of the measurement results is shown below. In addition, the site specified in the 1H NMR spectrum of the compound shown in the upper part of the figure is indicated by the same symbol as the alphabetic symbol attached to the corresponding peak of the 1H NMR spectrum shown in the lower part of the same figure. .

(Liquid Crystallinity Evaluation Test) The liquid crystallinity evaluation test was performed with a differential scanning calorimeter (DSC) and a polarizing microscope. In the DSC measurement, the temperature of the sample enclosed in the aluminum pan was measured at a rate of 5 ° C. per minute (only Example 13 was 10 ° C. per minute) in a nitrogen atmosphere. Moreover, the polarization microscope observation was performed by raising and lowering the temperature of a sample sandwiched between glass plates on a hot stage at a rate of 5 ° C. per minute and observing the phase state under crossed Nicols conditions.

(Evaluation of polymerization temperature) The evaluation of the polymerization temperature was performed by a differential scanning calorimeter (DSC). In the DSC measurement, the temperature of the sample enclosed in the aluminum pan was measured at a rate of 5 ° C. per minute in a nitrogen atmosphere. Since polymerization is observed as an exothermic reaction, in the examples, when measured under the above conditions by DSC, the exothermic reaction ends from the temperature at which the exothermic reaction starts (polymerization start temperature) in the temperature rising process. The temperature up to the temperature (polymerization completion temperature) was defined as the polymerization temperature.

<Example 1>
First, synthesis of the raw material phenol (liquid crystal phenol) represented by the formula (4)
Vora, RS Gupta, Molecular Crystals and Liquid Crystals, 56, 31 (1979).

  Specifically, 0.02 mol of 4-heptyloxybenzoic acid (manufactured by Wako Pure Chemical Industries, Ltd.) is taken in a three-necked flask, dissolved in 5 g of anhydrous THF, 0.2 mol of thionyl chloride is added, and several drops of DMF are added dropwise. The reaction was performed at 35 ° C. for 8 hours. Two traps were connected and the pressure was reduced with a diaphragm pump, and unreacted thionyl chloride was distilled for about 2 hours. Thereafter, the reaction temperature was set to 40 ° C., and the distillation was further continued for 2 hours by changing to a rotary vacuum pump. After returning to normal pressure with nitrogen purge, 20 ml of anhydrous THF and 0.02 mol of p-hydroxybenzaldehyde (manufactured by Wako Pure Chemical Industries, Ltd.) were added, and 0.02 mol of anhydrous pyridine was added dropwise. And reaction was performed at 50 degreeC under nitrogen atmosphere for 8 hours. Subsequently, 20 ml of methanol was added, and then the solution was dropped into 500 ml of water to cause reprecipitation. The reaction solution was filtered through a glass filter, and the collected solid was dissolved in acetone and dehydrated with anhydrous sodium sulfate.

  Anhydrous sodium sulfate was removed by filtration, vacuum concentration and vacuum drying (room temperature for several hours, further 80 ° C. for several hours) were carried out to obtain a white solid (I) in a yield of 5.06 g and a yield of 74.3%. Then, 0.015 mol of the obtained white solid (I) is placed in a three-necked flask, dissolved in 35 ml of ethanol, 0.015 mol of p-aminophenol (manufactured by Wako Pure Chemical Industries, Ltd.) is added, and then an oil bath is used. While heating to 100 ° C., refluxing was performed for 5 hours.

  The precipitate produced by reflux was collected by suction filtration using a glass filter, washed with 100 ml of methanol and dissolved in THF, and then dried with a diaphragm pump for about 20 minutes, followed by further vacuum drying (at 80 ° C. for 4 hours). Went. As a result, a white solid (II) was obtained in a yield of 4.02 g and a yield of 62.5%. A 1H NMR spectrum of the obtained product (white solid (II)) is shown in FIG.

  As can be seen from FIG. 1, the signal of the aldehyde group near 10 ppm disappears, the signal of azomethine appears at 8.4 ppm, and the integration ratio also matches, so the target product (raw material phenol) shown in the above formula (4) It was confirmed that.

  Next, take 10 ml of chloroform in a 50 ml three-necked flask, dissolve 2 mmol of butylamine (manufactured by Wako Pure Chemical Industries, Ltd.), add 4 mmol of formalin (37% aqueous solution) in terms of formaldehyde in an ice bath, and stir for 10 minutes. did. To this, 1 mmol (0.43 g) of white solid (II), which was the synthesized raw material phenol, was added and reacted at reflux temperature (about 61 ° C.) for 12 hours. After completion of the reaction, the reaction solution was dropped into 100 ml of methanol, and then the precipitate was filtered off. The filtered precipitate was washed with 10 ml of methanol and vacuum-dried, whereby the liquid crystalline benzoate represented by formula (5) was obtained. 0.30 g (yield 58%) of oxazine compound 1 was obtained.

  The structure of the obtained liquid crystalline benzoxazine-based compound 1 was determined by NMR, and it was confirmed from the 1H NMR spectrum that it was the target structure represented by the formula (5). Next, the obtained liquid crystalline benzoxazine-based compound 1 was evaluated for liquid crystallinity. The results are shown in Table 1.

<Example 2>
A liquid crystalline benzoxazine compound 2 represented by the formula (6) was synthesized by the same operation as in Example 1 except that the butylamine used in Example 1 was changed to methylamine (manufactured by Kishida Chemical Co., Ltd.). . The yield was around 50%. The structure of the obtained liquid crystalline benzoxazine-based compound 2 was determined by NMR, and it was confirmed from the 1H NMR spectrum that it was the target structure represented by the formula (6). Next, the obtained liquid crystalline benzoxazine-based compound 2 was evaluated for liquid crystallinity. The results are shown in Table 1.

<Example 3>
The liquid crystalline benzoxazine-based compound 3 represented by the formula (7) was prepared in the same manner as in Example 1 except that butylamine used in Example 1 was changed to octylamine (manufactured by Wako Pure Chemical Industries, Ltd.). Synthesized. The yield was around 50%.

  FIG. 2 is a 1H NMR spectrum of liquid crystalline benzoxazine compound 3 of Example 3. Since the signals of methylene protons of the oxazine ring were confirmed at around 4.0 ppm and 4.95 ppm and the integration ratio was also consistent, it was confirmed that the compound was a liquid crystalline benzoxazine compound 3 represented by formula (7). Next, the obtained liquid crystalline benzoxazine-based compound 3 was evaluated for liquid crystallinity. The results are shown in Table 1.

<Example 4>
First, a raw material phenol (azomethine phenol) represented by the formula (8) was synthesized.

  Specifically, 0.01 mol of terephthalaldehyde (manufactured by Wako Pure Chemical Industries, Ltd.) is taken in a three-necked flask, dissolved in 40 ml of THF, 0.01 mol of 4-n-octylaniline (manufactured by Tokyo Chemical Industry Co., Ltd.) is added and refluxed for 5 hours. Then, 0.01 mol of p-aminophenol (manufactured by Wako Pure Chemical Industries, Ltd.) was added and refluxed for 5 hours. Thereafter, the solvent was removed by drying under reduced pressure, followed by washing with methanol and then washing with hot hexane. And it dried under reduced pressure and obtained the yellow powdery product in 45% (1.86g) yield. The 1H NMR spectrum of the obtained yellow powdery product is shown in FIG.

  As can be seen from FIG. 3, the signal of azomethine was observed and the integrated values also coincided, so that the obtained yellow powder product was confirmed to be azomethine phenol represented by the formula (8).

  Next, take 10 ml of chloroform in a 50 ml three-necked flask, dissolve 2 mmol of octylamine (manufactured by Wako Pure Chemical Industries, Ltd.), add 4 mmol of formalin (37% aqueous solution) in terms of formaldehyde in an ice bath, and add 10 minutes. Stir. Further, 1 mmol (0.41 g) of azomethine phenol represented by the formula (8) obtained by the above operation was added, and the mixture was reacted at a reflux temperature (about 61 ° C.) for 12 hours. After completion of the reaction, the reaction solution is dropped into 100 ml of methanol, the precipitate is filtered off, and the precipitate separated by filtration is washed with 10 ml of methanol and dried in vacuo to give a liquid crystalline benzoxazine-based compound represented by formula (9). 0.29 g (yield 51%) of compound 4 was obtained.

  4 is a 1H NMR spectrum of liquid crystalline benzoxazine compound 4 of Example 4. FIG. The signals of methylene protons on the oxazine ring were confirmed at around 4.0 ppm and 4.95 ppm, and the integral ratio was also in agreement, confirming that it was a liquid crystalline benzoxazine compound 4 represented by formula (9). Next, the obtained liquid crystalline benzoxazine-based compound 4 was evaluated for liquid crystallinity. The results are shown in Table 1.

<Comparative Example 1>
Dioxane as a solvent is added to a three-necked flask, and 0.04 mol of formaldehyde, 1,4-butanediamine (manufactured by Wako Pure Chemical Industries, Ltd.) 0.01 mol, 4,4′-biphenol (manufactured by Wako Pure Chemical Industries, Ltd.) 0 .01 mol was sequentially added and reacted at 100 ° C. for 6 hours. The product was washed twice with a 1M-Na2CO3 aqueous solution and water, dried under reduced pressure, purified by reprecipitation in ether, and further dried under reduced pressure to obtain a powdery substance. The yield after purification was about 75%.

  From the 1H NMR spectrum shown in FIG. 5, it was confirmed that the obtained powdery substance was a benzoxazine-based compound 1 represented by the formula (10).

  Further, when the molecular weight (polystyrene conversion) was determined by size removal chromatography, the number average molecular weight was about 800 and the degree of polymerization l was about 2. Next, the obtained benzoxazine-based compound 1 was evaluated for liquid crystal properties. The results are shown in Table 1.

<Comparative Example 2>
Chloroform is added as a solvent to a three-necked flask, and 0.04 mol of formaldehyde, 0.02 mol of butylamine (manufactured by Wako Pure Chemical Industries, Ltd.), and 0.02 mol of 4,4′-biphenol (manufactured by Wako Pure Chemical Industries, Ltd.) are sequentially added. And refluxed for 6 hours.

  The product is washed once with 3M-NaOH aqueous solution, then washed with 0.5M-1M-HCl aqueous solution 2-3 times, further washed with 3M-NaOH aqueous solution 2-3 times, and finally neutralized with water. Washed until After dehydration with anhydrous sodium sulfate, it was dried under reduced pressure to obtain white crystals. The yield was about 45%.

  In the 1H NMR spectrum shown in FIG. 6, a signal of methylene protons of the oxazine ring can be confirmed around 4.0 ppm and 4.95 ppm, and the integral ratio also matches the alkylene chain and aromatic ring. It was confirmed that this was a benzoxazine-based compound 2 (n = 3) represented by the formula (11).

  The diamine was changed from butylamine to octylamine (manufactured by Wako Pure Chemical Industries, Ltd.), and white crystals were similarly obtained. Although not shown, it was confirmed from the 1H NMR spectrum that it was a benzoxazine compound 3 (n = 7) represented by the formula (11). Next, the obtained benzoxazine compounds 2 and 3 were evaluated for liquid crystallinity. The results are shown in Table 1.

<Comparative Example 3>
Chloroform is added to a three-necked flask as a solvent, and 0.02 mol of formaldehyde, 0.01 mol of butylamine (manufactured by Wako Pure Chemical Industries), 0.01 mol of 4-hydroxy-4′-cyanobiphenyl (manufactured by Tokyo Chemical Industry Co., Ltd.) Sequentially added and refluxed for 10 hours.

  The product was purified by recrystallization in hexane after drying under reduced pressure. Since cyanobiphenyl was dissolved in an alkaline solution, the washing operation was omitted. The yield after purification was about 24%. FIG. 7 shows the 1H NMR spectrum of the obtained yellow crystals.

  As can be seen from FIG. 7, the signals of methylene protons of the oxazine ring can be confirmed around 4.0 ppm and 4.95 ppm, and the integration ratio also matches that of the alkylene chain and aromatic ring, so that the benzoxazine having the structure shown in formula (12) It was confirmed to be System Compound 4. Next, the obtained benzoxazine-based compound 4 was evaluated for liquid crystallinity. The results are shown in Table 1.

<Comparative example 4>
Chloroform was taken in a three-necked flask and added in the order of 0.02 mol of formaldehyde, 0.01 mol of 4-n-butylaniline (manufactured by Tokyo Chemical Industry Co., Ltd.), 0.01 mol of 3-methoxyphenol (manufactured by Tokyo Chemical Industry Co., Ltd.), 95 Reflux was carried out for 12 hours at ° C. The product was washed twice with 0.5 M HCl aqueous solution and 1 M NaOH aqueous solution, respectively, and then washed with water until neutral, then dehydrated with anhydrous sodium sulfate, and dried under reduced pressure at room temperature (about 15 ° C.). did. Thereafter, it was further purified by recrystallization in hexane to obtain yellowish white crystals. The 1H NMR spectrum of the obtained yellowish white crystal is shown in FIG.

  As can be seen from FIG. 8, the signal of the oxazine ring is recognized, and the integrated values match with respect to the methyl of the methoxy group (indicated by S in FIG. 8). It was confirmed to be Oxazine-based Compound 5. Next, the obtained benzoxazine-based compound 5 was evaluated for liquid crystal properties. The results are shown in Table 1.

<Comparative Example 5>
In order to synthesize an aldehyde group-containing benzoxazine, chloroform was taken into a three-necked flask, 0.02 mol of butylamine and 0.04 mol of formaldehyde were added, and the mixture was refluxed at 95 ° C. for 5 hours. To this was added 0.02 mol of hydroxybenzaldehyde (manufactured by Wako Pure Chemical Industries, Ltd.), and the mixture was further refluxed for 12 hours. The product was washed three times with water, dehydrated with anhydrous sodium sulfate, and then dried under reduced pressure at room temperature (about 15 ° C.) to obtain an aldehyde group-containing benzoxazine at a yield of 95%.

  FIG. 9 shows the 1H NMR spectrum of the product (aldehyde group-containing benzoxazine). As can be seen from FIG. 9, the remaining of the aldehyde group and the formation of the oxazine ring were observed. Furthermore, in FIG. 9, it was confirmed that the proton of azomethine generated by the reaction of benzaldehyde and amine was not observed. Further, since the integrated value almost coincided with the theoretical value, the product was an aldehyde group-containing benzoxazine represented by the formula (14).

  Next, the solvent THF was taken into a three-necked flask, 0.01 mol of the obtained aldehyde group-containing benzoxazine and 0.005 mol of phenylenediamine (manufactured by Wako Pure Chemical Industries, Ltd.) were added, and the mixture was refluxed at 95 ° C. for 10 hours. The product was concentrated and then reprecipitated in hexane to obtain yellow crystals in a yield of 53%. FIG. 10 shows the 1H NMR spectrum of the obtained yellow crystals. As can be seen from FIG. 10, the presence of protons of the azomethine group (indicated by C in FIG. 10), the remaining of the oxazine ring, and the disappearance of the signal of the aldehyde group in the vicinity of 9.8 ppm were confirmed. Since it almost agreed with the value, it was confirmed that it was the target benzoxazine-based compound 6 having the chemical structure represented by the formula (15). Next, the obtained benzoxazine-based compound 6 was evaluated for liquid crystallinity. The results are shown in Table 1.

  As shown in Table 1, the compounds produced in Examples 1 to 4 (liquid crystalline benzoxazine compounds 1 to 4) exhibited liquid crystallinity. Table 1 shows the temperature range of the liquid crystal state detected. In Table 1, “-” indicates that the liquid crystal state was not detected by either DSC measurement or polarization microscope observation, and the blank indicates measurement (because curing occurred during the temperature rising process). Indicates that you are not going. Furthermore, the display of “*” in Table 1 indicates that the liquid crystal state was not detected in the polarization microscope observation. In addition, although the liquid crystallinity evaluation test was performed using both DSC measurement and polarization microscope observation as described above, the temperatures shown in Table 1 indicate the results obtained from the polarization microscope observation.

  Specifically, the liquid crystalline benzoxazine compound 1 synthesized in Example 1 became a nematic liquid crystal in the range of 76 ° C. to 87 ° C. and became a smectic liquid crystal in the range of 52 ° C. to 76 ° C. in the temperature lowering process. The liquid crystalline benzoxazine compound 2 synthesized in Example 2 becomes a nematic liquid crystal in the range of 90 ° C. to 122 ° C. in the temperature rising process, and also in the range of 62 ° C. to 123 ° C. in the temperature decreasing process. A smectic liquid crystal was formed in the range of 62 ° C. The liquid crystalline benzoxazine compound 3 synthesized in Example 3 became a nematic liquid crystal in the range of 64 ° C. to 76 ° C. in the temperature rising process, and became a smectic liquid crystal in the range of 30 ° C. to 73 ° C. in the temperature lowering process. The liquid crystalline benzoxazine compound 4 synthesized in Example 4 became a smectic liquid crystal in the range of 58 ° C. to 71 ° C. during the temperature lowering process.

  On the other hand, none of the benzoxazine compounds synthesized in Comparative Examples 1 to 5 showed liquid crystallinity. As is clear from the results in Table 1, the liquid crystalline benzoxazine compound of the present invention has a structure that exhibits liquid crystallinity, and can realize a benzoxazine compound that can be used as a liquid crystal monomer, which has been difficult in the past. .

<Example 5>
Liquid crystallinity shown in Formula (16) in the same manner as in Example 1 except that 4-heptyloxybenzoic acid used in Example 1 was changed to p-anisic acid (manufactured by Tokyo Chemical Industry Co., Ltd.). A benzoxazine compound 5 was synthesized. The yield was around 50%. The structure of the obtained liquid crystalline benzoxazine-based compound 5 was determined by NMR, and from 1H NMR spectrum, it was confirmed to be the target structure represented by the formula (16). Next, the obtained liquid crystalline benzoxazine-based compound 5 was evaluated for liquid crystallinity by observation with a polarizing microscope. The results are shown in Table 2.

<Example 6>
A liquid crystalline benzoxazine-based compound 6 represented by the formula (17) was synthesized in the same manner as in Example 5 except that butylamine was changed to methylamine (manufactured by Kishida Chemical Co., Ltd.) in Example 5. The yield was around 50%. When the structure of the obtained liquid crystalline benzoxazine compound 6 was determined by NMR, it was confirmed from the 1H NMR spectrum that it was the target structure represented by the formula (17). Next, the obtained liquid crystalline benzoxazine-based compound 6 was evaluated for liquid crystallinity by observation with a polarizing microscope. The results are shown in Table 2.

<Example 7>
A liquid crystalline benzoxazine compound 7 represented by the formula (18) was synthesized in the same manner as in Example 5 except that butylamine was changed to octylamine (manufactured by Kishida Chemical Co., Ltd.) in Example 5. The yield was around 50%. The structure of the obtained liquid crystalline benzoxazine-based compound 7 was determined by NMR, and it was confirmed from the 1H NMR spectrum that it was the target structure represented by the formula (18). Next, the obtained liquid crystalline benzoxazine-based compound 7 was evaluated for liquid crystal properties by observation with a polarizing microscope. The results are shown in Table 2.

<Example 8>
A liquid crystal represented by the formula (19) in the same manner as in Example 1 except that 4-heptyloxybenzoic acid used in Example 1 was changed to 4-butoxybenzoic acid (manufactured by Tokyo Chemical Industry Co., Ltd.). Benzoxazine compound 8 was synthesized. The yield was around 50%. When the structure of the obtained liquid crystalline benzoxazine compound 8 was determined by NMR, it was confirmed from the 1H NMR spectrum that it was the target structure represented by the formula (19). Next, the obtained liquid crystalline benzoxazine-based compound 8 was evaluated for liquid crystallinity by observation with a polarizing microscope. The results are shown in Table 2.

<Example 9>
A liquid crystalline benzoxazine compound 9 represented by the formula (20) was synthesized in the same manner as in Example 8 except that butylamine was changed to methylamine (manufactured by Kishida Chemical Co., Ltd.) in Example 8. The yield was around 50%. The structure of the obtained liquid crystalline benzoxazine-based compound 9 was determined by NMR, and from the 1H NMR spectrum, it was confirmed to be the target structure represented by the formula (20). Next, the obtained liquid crystalline benzoxazine-based compound 9 was evaluated for liquid crystallinity by observation with a polarizing microscope. The results are shown in Table 2.

<Example 10>
A liquid crystalline benzoxazine compound 10 represented by the formula (21) was synthesized in the same manner as in Example 9 except that methylamine was changed to octylamine (manufactured by Kishida Chemical Co., Ltd.) in Example 9. The yield was around 50%. The structure of the obtained liquid crystalline benzoxazine-based compound 10 was determined by NMR, and it was confirmed from the 1H NMR spectrum that it was the target structure represented by the formula (21). Next, the obtained liquid crystalline benzoxazine-based compound 10 was evaluated for liquid crystallinity by observation with a polarizing microscope. The results are shown in Table 2.

  The compounds synthesized in Examples 2, 5 to 10 shown in Table 2 (liquid crystalline benzoxazine compounds 2, 5 to 10) were all liquid crystalline. The compounds synthesized in Examples 5, 7, and 10 (liquid crystalline benzoxazine compounds 5, 7, and 10) exhibited liquid crystallinity only during the temperature lowering process. Table 2 shows the temperature range of the liquid crystal state detected in the temperature raising process. In Table 2, the display of “−” indicates that the liquid crystal state was not detected in either the DSC measurement or the polarization microscope observation. In addition, although the liquid crystallinity evaluation test was performed using both DSC measurement and polarization microscope observation as described above, the temperatures shown in Table 2 show the results obtained from the polarization microscope observation.

  The liquid crystalline benzoxazine compound 5 synthesized in Example 5 and the liquid crystalline benzoxazine compound 8 synthesized in Example 8 have structures that differ only in the number of carbon atoms of the alkoxy group constituting the atomic group R2. Carbon number of the alkoxy group of the liquid crystalline benzoxazine-based compound 5 and the liquid crystalline benzoxazine-based compound 8 is 1, 4 respectively.

  The liquid crystalline benzoxazine compound 5 showed liquid crystallinity only in the temperature lowering process and did not show liquid crystallinity in the temperature rising process, but the liquid crystalline benzoxazine compound 8 was in the range of 75 ° C. to 95 ° C. in the temperature rising process. It became nematic liquid crystal.

  The liquid crystalline benzoxazine compound 2 synthesized in Example 2, the liquid crystalline benzoxazine compound 9 synthesized in Example 9, and the liquid crystalline benzoxazine compound 6 synthesized in Example 6 also constitute the atomic group R2. Only the number of carbon atoms of the alkoxy group is different, and the other parts are compounds of the same structure. The carbon number of the alkoxy group of the liquid crystalline benzoxazine-based compound 2, the liquid crystalline benzoxazine-based compound 9, and the liquid crystalline benzoxazine-based compound 6 is 7, 4, and 1, respectively.

  The liquid crystalline benzoxazine-based compound 2 became a nematic liquid crystal in the range of 90 ° C to 122 ° C. The liquid crystalline benzoxazine compound 9 became a nematic liquid crystal in the range of 80 ° C to 136 ° C. The liquid crystalline benzoxazine-based compound 6 became a nematic liquid crystal in the range of 152 ° C to 161 ° C. In the liquid crystalline benzoxazine compounds 2, 6, and 9, the upper limit of the liquid crystal temperature range tended to increase as the number of carbon atoms of the alkoxy group decreased.

  Thus, it was shown that by slightly changing the structure of the alkoxy group serving as the spacer (changing the number of carbon atoms), the liquid crystal characteristics can be changed, and the temperature range can also be changed (increased in temperature). According to this, the liquid crystal temperature range can be adjusted while maintaining the characteristics of benzoxazine other than liquid crystallinity derived from the structure.

<Example 11>
To the liquid crystalline benzoxazine compound 2 produced in Example 2, paratoluenesulfonic acid was added as an additive to produce a liquid crystalline benzoxazine polymer composition. Specifically, the liquid crystalline benzoxazine compound 2 was placed in a 5 ml sample tube, and a predetermined amount of paratoluenesulfonic acid (manufactured by Wako Pure Chemical Industries, Ltd.) was added and dissolved in 1 ml of THF. The solvent was removed by vacuum drying to obtain a white solid sample to be a liquid crystalline benzoxazine-based polymerization composition. In this example, three kinds of liquid crystalline benzoxazines having different compounding ratios, in which 0.4, 2, and 4 parts by weight of paratoluenesulfonic acid were added to the liquid crystalline benzoxazine compound 2 (100 parts by weight), respectively. Polymerization compositions were prepared, and liquid crystal properties of each were evaluated by observation with a polarizing microscope. Further, the polymerization temperature (polymerization temperature range) was measured by DSC measurement. The results are shown in Table 3.

  As shown in Table 3, in the present liquid crystalline benzoxazine-based polymerization composition in which paratoluenesulfonic acid is blended with liquid crystalline benzoxazine-based compound 2, the liquid crystalline benzoxazine-based compound 2 to which paratoluenesulfonic acid is not added is added. Compared with a wider liquid crystal temperature range.

  Specifically, a composition containing 0.4 parts by weight of paratoluenesulfonic acid becomes a nematic liquid crystal in the range of 104 ° C. to 161 ° C. during the temperature rising process, and a composition containing 2 parts by weight of paratoluenesulfonic acid is 105 A nematic liquid crystal was obtained in the range of 168 ° C. to 168 ° C., and a composition containing 4 parts by weight of paratoluenesulfonic acid became a nematic liquid crystal in the range of 100 ° C. to 170 ° C. In addition, as a result of measuring the polymerization temperature range of each liquid crystalline benzoxazine-based polymerization composition and liquid crystalline benzoxazine-based compound 2 with a differential scanning calorimeter (DSC), liquid crystal benzoic acid was blended. Compared to the oxazine compound 2 alone, it was observed that the polymerization end temperature shifts to the low temperature side and shifts to the low temperature side in proportion to the amount of the additive.

  Thus, when the present liquid crystalline benzoxazine-based polymer composition is used, the liquid crystal temperature range of the liquid crystalline benzoxazine-based compound can be extended and the upper limit temperature can be increased. In addition, it was shown that the liquid crystalline benzoxazine-based compound can be polymerized on the low temperature side as compared with the case of polymerizing the single compound. Therefore, even if there is a gap between the liquid crystal temperature range of the liquid crystalline benzoxazine-based compound and the polymerization temperature, the liquid crystalline benzoxazine-based compound is polymerized in the liquid crystal state by using the present liquid crystalline benzoxazine-based polymerized composition. Can be made easier.

<Example 12>
To the liquid crystal benzoxazine compound 2 prepared in Example 2, 2-ethyl-4-methylimidazole was added as an additive to prepare a liquid crystal benzoxazine polymer composition. Specifically, the liquid crystalline benzoxazine compound 2 was placed in a 5 ml sample tube, and a predetermined amount of 2-ethyl-4-methylimidazole (manufactured by Wako Pure Chemical Industries, Ltd.) was added and dissolved in 1 ml of THF. The solvent was removed by vacuum drying to obtain a white solid sample to be a liquid crystalline benzoxazine-based polymerization composition. In this example, two types of liquid crystalline benzoxazines having different blending ratios, each of which was added 1.5 parts by weight of 2-ethyl-4-methylimidazole to liquid crystalline benzoxazine based compound 2 (100 parts by weight). Polymerization compositions were prepared, and for each, liquid crystal properties were evaluated by observation with a polarizing microscope. Further, the polymerization temperature (polymerization temperature range) was measured by DSC measurement. The results are shown in Table 4.

<Comparative Example 6>
A liquid crystalline benzoxazine-based polymer composition was prepared in the same manner as in Example 12 except that 10 parts by weight of 2-ethyl-4-methylimidazole blended with the liquid crystalline benzoxazine-based compound 2 was used. It was performed by microscopic observation. Further, the polymerization temperature (polymerization temperature range) was measured by DSC measurement. The results are shown in Table 4.

  As shown in Table 4, the liquid crystalline benzoxazine-based polymer composition prepared in Example 12, that is, the liquid crystalline benzoxazine-based compound 2 blended with 2-ethyl-4-methylimidazole has a liquid crystal temperature range of It was observed that the maximum temperature increased. Moreover, it was recognized that the polymerization end temperature shifts to a lower temperature side and shifts to a lower temperature side in proportion to the amount of the additive as compared with the liquid crystalline benzoxazine-based compound 2 alone.

  Specifically, a composition containing 1 part by weight of 2-ethyl-4-methylimidazole becomes a nematic liquid crystal in the range of 108 ° C. to 135 ° C. in the temperature rising process, and a composition containing 5 parts by weight is 94 ° C. to 126 ° C. A nematic liquid crystal was formed in the temperature range.

  As described above, when the present liquid crystalline benzoxazine-based polymerization composition is used, the upper limit temperature of the liquid crystal temperature range of the liquid crystalline benzoxazine-based compound is increased and compared with the case of polymerizing the liquid crystalline benzoxazine-based compound alone, It was shown that polymerization can be performed on the low temperature side.

  On the other hand, the composition containing 10 parts by weight of 2-ethyl-4-methylimidazole of Comparative Example 6 became a nematic liquid crystal in the range of 80 ° C to 100 ° C. In addition, the upper limit temperature of the liquid crystal temperature range decreased and the polymerization end temperature shifted to the high temperature side as compared with the liquid crystalline benzoxazine compound 2 alone. As a result, it was shown that when 2-ethyl-4-methylimidazole was used as an additive and blended for the purpose of lowering the polymerization temperature, the optimum blending range was less than 10 parts by weight.

<Example 13>
The liquid crystalline benzoxazine compound 2 synthesized in Example 2 was dissolved in THF, and 0.4 parts by weight of paratoluenesulfonic acid was added to the liquid crystalline benzoxazine compound 2 (100 parts by weight) at room temperature. Stir. The solution became cloudy after 1 hour. When NMR measurement was performed on the obtained mixture, it was found that the ring-opening polymerization of the liquid crystalline benzoxazine-based compound 2 partially proceeded.

  A film was prepared by casting the THF solution on a glass plate, and was observed with a polarizing microscope at a heating rate of 10 ° C. per minute. In a state where the benzoxazine ring was partially ring-opened polymerized, 100 to 160 ° C. Nematic liquid crystal phase was exhibited in the temperature range of. An experiment was conducted in the same procedure except that the addition amount of p-toluenesulfonic acid was changed to 2 and 4 parts by weight. In both cases, the nematic liquid crystal phase was increased in the temperature rising process in the state in which the ring-opening polymerization of benzoxazine proceeded. showed that. Specifically, a nematic liquid crystal phase was observed in a polarizing microscope under a temperature range of 100 to 170 ° C. when the amount of added paratoluenesulfonic acid was 2 parts by weight and 95 to 170 ° C. when 4 parts by weight.

  Thus, according to the present liquid crystalline benzoxazine-based polymerization composition containing the liquid crystalline benzoxazine-based compound and an additive, it was shown that the polymerization temperature of the liquid crystalline benzoxazine-based compound can be lowered to room temperature. Since the polymerization proceeds more easily as the energy supplied from the outside increases, it is general that what is polymerized at room temperature is more easily polymerized at a higher temperature. Therefore, this polymerization composition can be sufficiently polymerized in the temperature range where the liquid crystal phase is observed, that is, it can be provided as a composition that can be polymerized in the liquid crystal state to form a polybenzoxazine-based resin.

Claims (9)

In a benzoxazine-based compound that has a high molecular weight by a polymerization reaction,
A benzoxazine ring,
The plurality of benzene rings are directly or indirectly connected to each other such that the plurality of benzene rings are arranged along one direction, and at one of the connection ends A first atomic group in which a benzene ring is directly or indirectly connected to the benzene ring of the benzoxazine ring;
A second atomic group that is bonded to at least one of the benzene ring at the other linking end of the plurality of benzene rings or the hetero ring of the benzoxazine ring in the first atomic group and imparts flexibility to the molecule. ,
1. A liquid crystalline benzoxazine compound having a liquid crystallinity and having an asymmetric structure in which one benzoxazine ring is contained in the molecular structure.   The first atomic group includes a functional group for bonding the plurality of benzene rings and a functional group for bonding the benzene ring at the one connection end to the benzoxazine ring. The liquid crystalline benzoxazine-based compound according to claim 1, wherein   The liquid crystalline benzoxazine compound according to claim 2, wherein the functional group includes at least one of an imino group and an ester group.   4. The liquid crystalline benzoxazine-based compound according to claim 2, wherein the functional group for bonding the plurality of benzene rings is located in the para position via the bonded benzene rings. 5. The liquid crystallinity according to claim 4, wherein the first atomic group is represented by the following general formula (1) and is bonded to a benzoxazine ring through an imino group. Benzoxazine compounds.

5. The liquid crystal according to claim 4, wherein the first atomic group is represented by the following general formula (2) and is bonded to a benzoxazine ring via an imino group. Benzoxazine compounds.

  The liquid crystalline benzoxazine-based compound according to any one of claims 1 to 6, wherein the second atomic group is an alkyl group or an alkoxy group.   It contains the liquid crystalline benzoxazine-based compound according to claim 1 and at least one additive selected from any one of an inorganic acid, an inorganic base, an organic acid, and an organic base. Liquid crystalline benzoxazine-based polymerization composition.   The liquid crystalline benzoxazine-based polymerization composition according to claim 8, wherein the additive is p-toluenesulfonic acid or imidazole.

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