TW202012488A - Method for producing liquid-crystalline resin - Google Patents

Abstract

A method for producing a liquid-crystalline resin by reacting one or more starting-material monomers comprising at least one compound selected from the group consisting of aromatic hydroxycarboxylic acids and polymerizable derivatives thereof, the method including a step in which the starting-material monomers are condensation-polymerized in the presence of either an acidic compound having a B-O (boron-oxygen) bond or a compound capable of yielding the acidic compound in the reaction system.

Description

Liquid crystal resin manufacturing method

The invention relates to a method for manufacturing liquid crystal resin.

Liquid crystal resins typified by liquid crystal polyester resins are widely used in various fields due to their good high fluidity, low barrier properties, and reflow resistance. Such liquid crystal resins can be selected by appropriately combining the raw material monomers such as aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, and aromatic diol to obtain the desired physical properties of the liquid crystal resin. Obtained by polycondensation. In practice, the mixture of raw material monomers is usually premixed with an acetylating agent (acetic anhydride, etc.), and then a polycondensation reaction is performed.

In the production of liquid crystalline resins, in order to increase the speed of the polycondensation reaction, for example, various catalysts are used. Among them, when potassium acetate is used as a catalyst, there is a tendency to generate too much gas in the reaction. This is presumably due to the presence of the base potassium acetate, due to the carboxyl terminus of the liquid crystal resin (-COOH) into a carboxylic acid ion (-COO ^-) is activated as a carbonic acid gas becomes easily detached. In order to suppress the generation of carbon dioxide gas, it can be considered to proceed under acidic conditions using an acid catalyst in the polycondensation reaction. Examples of the acid catalyst include aliphatic sulfonic acid and aromatic sulfonic acid (see Patent Document 1). [Prior Technical Literature] [Patent Literature]

Patent Literature 1: International Publication No. 2015/016141

[Problems to be solved by the invention]

However, according to studies by the present inventors, it has been found that when an acid catalyst such as aliphatic sulfonic acid or aromatic sulfonic acid is used, the generation of carbonic acid gas can be suppressed, but the polycondensation rate cannot be sufficiently increased. When an acid catalyst such as the above is used, it is presumed that the terminal carboxyl group of the liquid crystalline resin can exist stably, and the generation of carbonic acid gas due to the terminal carboxyl group is reduced, but p-hydroxybenzene which is not easily distilled out of the system is generated Formic acid requires time for polycondensation. On the other hand, if only the suppression of the generation of carbon dioxide gas is considered, although the polycondensation reaction can be carried out without a catalyst, it is of course impossible to increase the polycondensation speed without a catalyst. From the above, in the production of the liquid crystalline resin, the use of an acid catalyst suppresses the generation of carbon dioxide gas, which contributes to an increase in the speed of polycondensation.

The present invention has been completed in view of the above-mentioned problems, and this object is to provide a method for producing a liquid crystalline resin, which can achieve both reduction in generation of carbonic acid gas and increase in polycondensation speed. [Means for solving the problem]

The inventors have found that in an acidic compound or reaction system having a BO (boron-oxygen) bond, in the presence of a compound that can produce the above-mentioned acidic compound, when the polycondensation reaction to obtain a liquid crystalline resin is performed, the polymerization reaches The improvement of the condensation reaction speed can also reduce the generation of gas, thus completing the present invention. The aspect of the present invention that solves the above-mentioned problems is as follows. (1) A method for producing a liquid crystalline resin, a method for producing a liquid crystalline resin by reacting at least one raw material monomer selected from the group consisting of aromatic hydroxycarboxylic acids and polymerizable derivatives thereof, including : The above-mentioned raw material monomer is a polycondensation step in the presence of an acidic compound having a BO (boron-oxygen) bond, or a compound that can generate the above-mentioned acidic compound in the reaction system.

(2) The method for producing a liquid crystalline resin according to (1) above, wherein, before the polycondensation step, the raw material monomer further includes an acidic compound having a BO (boron-oxygen) bond, or a reaction system The step of acylating in the presence of a compound that can produce the above compound.

(3) The method for producing a liquid crystalline resin according to (1) or (2) above, wherein in the polycondensation step, a compound having a tertiary amine or an oxide thereof is further present.

(4) The method for producing a liquid crystalline resin according to any one of (1) to (3) above, wherein the acidic compound having a BO (boron-oxygen) bond is at least one electron in an aryl group An attractive group of arylboronic acid (arylboronic acid). [Effect of invention]

According to the present invention, it is possible to provide a method for producing a liquid crystalline resin, which can achieve both reduction of generation of carbonic acid gas and improvement of polycondensation speed.

The method for producing a liquid crystalline resin of this embodiment is a method for producing a liquid crystalline resin by reacting at least one raw material monomer selected from the group consisting of aromatic hydroxycarboxylic acids and polymerizable derivatives thereof. Then, it is characterized by including: an acid compound having a BO (boron-oxygen) bond as a raw material monomer (hereinafter, referred to as "a compound containing a BO bond"), or a compound that can generate the above acid compound in the reaction system ( Hereinafter, these are collectively referred to as a "BO-bond-containing compound, etc." step of performing polycondensation.

In the method for producing a liquid crystalline resin of this embodiment, since the raw material monomer is polycondensed in the presence of a BO-bond-containing compound or the like as a catalyst, the generation of carbonic acid gas can be reduced, and the polymerization rate can be increased . In other words, it is possible to suppress the side reaction accompanying the polycondensation reaction, and at the same time, since it can be manufactured in a shorter time than in the past, it becomes possible to reduce the cost. Furthermore, the step of acetylation reaction is preferably carried out in the presence of the above-mentioned B—O-bonding-containing compound or the like. By performing both the acylation step and the polycondensation step in the presence of the above-mentioned B—O-bonding-containing compound, etc., the liquid crystalline resin can be produced in a shorter time.

In the liquid crystalline resin of the present embodiment, the "liquid crystallinity" refers to the property of forming an optically anisotropic melt phase. The properties of the anisotropic melt phase can be confirmed by a conventional polarized light detection method using an orthogonal polarizer. More specifically, the confirmation of the anisotropic molten phase was carried out by using a Leitz polarizing microscope and observing the molten sample carried on the Leitz hot stage at a magnification of 40 times under a nitrogen atmosphere. When the resin having liquid crystallinity is detected between the right-angle polarizing elements, even in the melt-static state, the polarized light still penetrates normally, showing optical anisotropy.

(Raw material monomer) The raw material monomer contains at least one compound selected from the group consisting of aromatic hydroxycarboxylic acids and polymerizable derivatives thereof. The aromatic hydroxycarboxylic acid and its polymerizable derivatives are not particularly limited, and examples thereof include p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, m-hydroxybenzoic acid, and 6-hydroxy-3-naphthalene Formic acid, 6-hydroxy-4-naphthoic acid, 4-hydroxy-4'-carboxydiphenyl ether, 2,6-dichloro-p-hydroxybenzoic acid, 2-chloro-p-hydroxybenzoic acid, 2,6-bis Methyl-p-hydroxybenzoic acid, 2,6-difluoro-p-hydroxybenzoic acid, 4-hydroxy-4'-biphenylcarboxylic acid, vanillic acid, etc. At least one compound selected from these can be used. Among them, from the viewpoint of easy availability, it is preferable to use at least one selected from p-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid.

It is preferable that the raw material monomer further satisfies the following (1) or (2). (1) A compound containing at least one compound selected from the group consisting of aromatic or alicyclic dicarboxylic acids and their polymerizable derivatives, or, (2) A compound containing at least one compound selected from the group consisting of aromatic or alicyclic dicarboxylic acids and their polymerizable derivatives, and At least one compound selected from the group consisting of aromatic or alicyclic diols, aromatic or alicyclic hydroxylamines, aromatic or alicyclic diamines, and polymerizable derivatives thereof.

The aromatic dicarboxylic acid is not particularly limited, and examples thereof include terephthalic acid, isophthalic acid, 4,4′-diphenyldicarboxylic acid, 2,6-naphthyldicarboxylic acid, and The compound represented by the following general formula (1) and the like.

(Y：為選自-(CH₂ )_n -(n=1~4)及-O(CH₂ )_n O-(n=1~4)的基)。[Chemical 1]

(Y: a group selected from -(CH ₂ ) _n -(n=1 to 4) and -O(CH ₂ ) _n O-(n=1 to 4)).

The alicyclic dicarboxylic acid is not particularly limited, and examples thereof include 1,4-cyclohexane dicarboxylic acid and 1,3-cyclopentane dicarboxylic acid. The polymerizable derivative is not particularly limited, and examples thereof include alkyl esters (about 1 to 4 carbon atoms) and halides of the above compounds.

The aromatic diol is not particularly limited, and examples thereof include 2,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4,4′-dihydroxybiphenyl, hydroquinone, and resorcinol. , The compound represented by the following general formula (II), the compound represented by the following general formula (III), and the like.

(X：為選自伸烷基(alkylene)(C₁ ~C₄ )、亞烷基(alkylidene)、-O-、-SO-、-SO₂ -、-S-、及-CO-的基)。[Chem 2]

(X: is a group selected from alkylene (C ₁ to C ₄ ), alkylidene, -O-, -SO-, -SO ₂ -, -S-, and -CO- ).

。[Chemical 3]

.

The alicyclic glycol is not particularly limited, and examples thereof include 1,4-cyclohexanedimethanol and 1,4-cyclohexanediol. The polymerizable derivative is not particularly limited, and examples thereof include alkyl esters (about 1 to 4 carbon atoms) and halides of the above compounds.

The aromatic hydroxylamine is not particularly limited, and examples thereof include p-aminophenol and (m-aminophenol). The alicyclic hydroxylamine is not particularly limited, and examples thereof include (4-hydroxycyclohexanecarboxylic acid and 3-hydroxycyclopentanecarboxylic acid). The polymerizable derivative is not particularly limited, and examples thereof include alkyl esters (about 1 to 4 carbon atoms) and halides of the above compounds.

Examples of aromatic diamines include p-phenylenediamine. The alicyclic diamine is not particularly limited, and examples thereof include 1,4-cyclohexanediamine and 1,3-cyclopentanediamine. The polymerizable derivative is not particularly limited, and examples thereof include alkyl esters (about 1 to 4 carbon atoms) and halides of the above compounds.

As a specific combination of raw material monomers, for example, (I) (a) contains at least one compound selected from the group consisting of aromatic hydroxycarboxylic acids and their polymerizable derivatives, or, (II) A compound containing (a) at least one member selected from the group consisting of aromatic hydroxycarboxylic acids and polymerizable derivatives thereof, and (b) at least one member selected from aromatic or alicyclic dicarboxylic acids Compounds of the group consisting of and their polymerizable derivatives, and (c) at least one selected from aromatic or alicyclic diols, aromatic hydroxylamines, aromatic diamines, and their polymerizable derivatives A combination of compounds in a group of substances. In addition, a molecular weight modifier may be used in combination with the above-mentioned constituents if necessary.

[醯化] In the production method of the present embodiment, before the following polycondensation, a step of acetylating the above-mentioned raw material monomers using an acetylating agent may be provided. The acylation is preferably carried out in the presence of the above-mentioned B-O-containing compound or the like. Examples of acetylating agents include acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, valeric anhydride, trimethylacetic anhydride, 2-ethylhexanoic anhydride, chloroacetic anhydride, dichloroacetic anhydride, and trichloroethyl Anhydride, bromoacetic anhydride, dibromoacetic anhydride, tribromoacetic anhydride, fluoroacetic anhydride, difluoroacetic anhydride, trifluoroacetic anhydride, glutaric anhydride, maleic anhydride, succinic anhydride, β-bromopropionic anhydride, etc. , But not particularly limited. At least one kind selected from these can be used. From the viewpoint of price and operability, carboxylic acid anhydrides such as acetic anhydride, propionic anhydride, butyric anhydride, and isobutyric anhydride are suitable examples. Among them, acetic anhydride is preferred from the viewpoint of easy availability. From the viewpoint of easy control of the reaction, the use amount of the acetylating agent is preferably 1.0 to 1.1 equivalents, and more preferably 1.01 to 1.05 equivalents, of the total hydroxyl groups of the substances used in the reaction.

The acylation can be performed by a known method. For example, a raw material monomer and an acetylating agent are mixed and heated at a temperature range of 120 to 160°C for 0.5 to 5 hours to perform an acylation reaction, and a reaction product containing an acylation product can be obtained.

[Polycondensation] The raw material monomer is subjected to polycondensation in the presence of a compound containing a B-O bond or the like. Moreover, when the above-mentioned acetylation step is provided, and when the above-mentioned BO-bond-containing compound and the like are used in this step, the BO-bond-containing compound and the like used in polycondensation may be the same as the user of the acylation , Can also be different.

(Acid compound with B-O bond) In the production method of this embodiment, during the polycondensation of the raw material monomer, although an acidic compound having a BO bond is used as a catalyst, by using a compound containing a BO bond, it is possible to achieve the generation of carbon dioxide gas Increase with polycondensation speed. Even if there is a compound containing a B-O bond in the polycondensation reaction, since the compound containing the B-O bond is weakly acidic, the polymerization system can tend to be weakly acidic, so that the terminal carboxyl group can exist stably. Therefore, the generation of carbon dioxide gas is reduced. In addition, the terminal carboxyl group reacts with a compound containing a B-O bond to form a boronic ester, and the electron attractivity is improved. Therefore, since the hydroxyl group of the raw material monomer is attracted, the polycondensation speed is increased. On the other hand, when a general acid catalyst such as aromatic sulfonic acid is used, it is not the terminal carboxyl group but the ester group is preferentially activated. Because the stronger ester group is activated, side reactions tend to occur. On the other hand, the B—O-bonding-containing compound used in this embodiment mainly activates the terminal carboxyl group, and proceeds with a polycondensation reaction using the terminal carboxyl group as a starting point, so that side reactions are less likely to occur.

Examples of the BO bond-containing compound include boronic acid derivatives such as boronic acid, aryl boronic acid, fluorine-substituted boronic acid, and boric acid, among which Preferably, arylbenzeneboronic acid and boric acid are used.

As the compound containing a B-O bond, when an arylboronic acid having at least one electron-attracting group in the aryl group is used, the electron-attracting property is improved, and it is preferable from the viewpoint of further increasing the polycondensation rate. Examples of the electron attracting group include halogen such as trifluoromethyl group, fluorine group, and chlorine group, nitro group, cyano group, and ketone group.

Alternatively, in this embodiment, in addition to directly using the B-O-containing compound, a compound that can produce the B-O-containing compound may be used in the reaction system. By producing a compound containing a B-O bond in the reaction system, the same effect as when using a compound containing a B-O bond is achieved. Examples of this compound include boronic anhydride and the like. These compounds can produce the above acid in the reaction system by the presence of carboxylic acid and heating.

The acid dissociation constant pKa of the compound containing the B-O bond is preferably 14 or less, more preferably -1.0 to 13 and even more preferably 0 to 12. In addition, the above-mentioned pKa refers to pKa in an aqueous solution at 25°C.

In the present embodiment, the addition amount of the above-mentioned B-O-containing compound or a compound that can generate a B-O-containing compound in the reaction system is not particularly limited as long as it does not adversely affect acylation or polycondensation. The compound is generally preferably 50 to 2000 ppm, and more preferably 100 to 1000 ppm relative to the theoretical yield of liquid crystal resins available. In addition, the temperature during polycondensation is preferably 300 to 400°C.

In the step of polycondensation, a compound having a tertiary amine or an oxide thereof is preferably present. As described above, in the polycondensation reaction in this embodiment, first, the terminal carboxyl group is dehydrated and synthesized with the BO-containing compound to form a borate ester. However, when a compound having a tertiary amine or its oxide exists, This compound partially replaces the boronic acid to a more active ester. That is, since the electron seeking property of the terminal carboxyl group becomes higher, the rate of polycondensation further increases.

Examples of the compound having a tertiary amine or its oxide include dimethylaminopyridine oxide (DMAPO), N,N-dimethyl-4-aminopyridine (DMAP), and 4-methoxypyridine- N-oxide (MPO), 4-pyrrolidinylpyridine-N-oxide (PPYO), N,N-isopropylethylamine, trimethylamine, triethylamine, etc. Among them, dimethylaminopyridine oxide having stronger nucleophilicity is preferable.

In the present embodiment, the addition amount of the compound having a tertiary amine or its oxide is generally preferably 50 to 2000 ppm, and more preferably 100 to 1000 ppm relative to the theoretical yield of liquid crystal resins that can be obtained.

(Solid phase polymerization step) The method for producing a liquid crystalline resin of this embodiment may further include a step of further solid-phase polymerizing the resin obtained in the melt polymerization step (the above-mentioned polycondensation step). By solid phase polymerization, the molecular weight of the raw material resin can be increased, and a liquid crystal resin excellent in strength, heat resistance, etc. can be obtained.

The solid-phase polymerization can use a method known in the past. For example, it can be carried out by heating at a temperature 10 to 120°C lower than the liquid crystal forming temperature of the raw resin in an inert gas flow such as nitrogen under reduced pressure or vacuum. Moreover, since the melting point of the liquid crystal resin increases with solid-phase polymerization, it is possible to perform solid-phase polymerization above the original melting point of the raw material resin. The solid-phase polymerization can be carried out at a certain temperature or at a stepwise high temperature. The heating method is not particularly limited, and microwave heating, heater heating, and the like can be used.

[Liquid crystal resin] The liquid crystalline resin obtained by the production method of this embodiment preferably contains at least one selected from the liquid crystalline polyester and the liquid crystalline polyester amide. The liquid crystalline polyester and the liquid crystalline polyester amide are not particularly limited, but aromatic polyester or aromatic polyester amide is preferred. In addition, it may be a polyester containing an aromatic polyester or an aromatic polyester amide in part in the same molecular chain.

As the aromatic polyester or aromatic polyester amide, more specifically, (1) is a polymer mainly composed of (a) one or more aromatic hydroxycarboxylic acids and derivatives thereof ester; (2) Mainly composed of (a) one or more aromatic hydroxycarboxylic acids and their derivatives and (b) Polyesters composed of one or more aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and derivatives thereof; (3) Mainly composed of (a) one or more aromatic hydroxycarboxylic acids and their derivatives and (b) One or more aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and their derivatives and (c) One or more aromatic diols, alicyclic diols , Polyester composed of aliphatic diols and their derivatives; (4) Mainly composed of (a) one or more aromatic hydroxycarboxylic acids and their derivatives and (c1) One or more aromatic hydroxylamines, aromatic diamines, and their derivatives and (c2) One or more aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and Polyamides derived from derivatives; (5) Mainly composed of (a) one or more aromatic hydroxycarboxylic acids and their derivatives and (b) One or more aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and their derivatives and (c1) One or more aromatic hydroxylamines, aromatic diamines, and their Polyesteramides composed of derivatives and (c2) one or more aromatic diols, alicyclic diols, and derivatives thereof.

The molecular weight of the liquid crystalline resin (number average molecular weight Mn) is not particularly limited, and the resin obtainable in the melt polymerization step is preferably 10,000 to 100,000, more preferably 15,000 to 80,000. As the resin obtainable in the solid-phase polymerization step, 12,000 to 120,000 are preferred, and 15,000 to 100,000 are more preferred. In addition, the number average molecular weight Mn can be measured with a gel filtration chromatography.

The melting point of the liquid crystal resin is not particularly limited, and may be 250 to 380°C. The melt viscosity of the liquid crystalline resin is not particularly limited. As a resin obtainable by melt polymerization, the melt viscosity measured at a cylinder temperature and a shear rate of 1000 sec ^-1 higher than the melting point of the liquid crystal resin by 5 Pa at 5 Pa ‧S above 150Pa‧s is better, 10Pa‧s above 100Pa‧s is better In addition, the melt viscosity measured at the cylinder temperature and shear rate of 1000 sec ^-1 higher than the melting point of the liquid crystalline resin when the solid phase polymerization step is performed is 5 Pa‧s or more and 200 Pa‧s or less Preferably, more than 10Pa‧s and less than 150Pa‧s are better.

The so-called "cylinder temperature that is 10 to 30°C higher than the melting point of the liquid crystal resin" refers to the temperature of the cylinder that can melt the liquid crystal resin to the extent that the melt viscosity can be measured. It is within the range of 10~30℃ according to the type of raw resin. The liquid crystalline resin may be in the form of a mixture of fine particles, or may be in the form of a molten mixture (melt-kneaded material) such as a pellet. [Example]

Hereinafter, the present embodiment will be described more specifically by way of examples, but the present embodiment is not limited to the following examples.

[Example 1] After introducing the following raw materials into the polymerization vessel, the temperature of the reaction system was raised to 140°C, and the reaction was carried out at 140°C for 3 hours (acidification). Thereafter, the temperature was further increased to 360°C in 4.5 hours, and the pressure was reduced to 10 Torr (that is, 1330 Pa) in 15 minutes, and polycondensation was carried out while distilling off acetic acid, excess acetic anhydride, and other low-boiling components. The time from the start of depressurization until the stirring torque reaches a predetermined value is 20 minutes. After the stirring torque reached a predetermined value, nitrogen gas was introduced to continuously pressurize from a decompressed state to a pressurized state, and the polymer was discharged from the bottom of the polymerization vessel. Thereafter, the strand is pelletized to obtain a liquid crystal resin tablet ingot. (raw material) 4-hydroxybenzoic acid (HBA): 184g (60mol%) Terephthalic acid (TA): 52g (14mol%) Isophthalic acid (IA): 22g (6 mol%) 4,4’-dihydroxybiphenyl (BP): 83g (20mol%) Phenylboronic acid (phenylboronic aicd): 54mg (180ppm) (catalyst; containing B-O bonding compound) Acidification agent (acetic anhydride): 233g.

[Example 2] In addition, except having added dimethylaminopyridine oxide, it carried out similarly to Example 1, and obtained the liquid crystalline resin sheet ingot. However, the amount of dimethylaminopyridine oxide used is shown in Table 1.

[Example 3] A liquid crystal resin tablet ingot was obtained in the same manner as in Example 1, except that the compound containing a B-O bond was changed to 3,5-bis(trifluoromethyl)phenylboronic acid. However, the amount of 3,5-bis(trifluoromethyl)phenylboronic acid used is shown in Table 1.

[Example 4] A liquid crystal resin tablet ingot was obtained in the same manner as in Example 1, except that the B-O-containing bonding compound was changed to boric acid. However, the amount of boric acid used is shown in Table 1.

[Comparative Example 1] A liquid crystal resin tablet ingot was obtained in the same manner as in Example 1, except that phenylboronic acid was changed to potassium acetate. However, the amount of potassium acetate used is shown in Table 1.

[Comparative Example 2] A liquid crystal resin tablet ingot was obtained in the same manner as in Example 1, except that phenylboronic acid was not used, that is, no catalyst was used.

[Polycondensation Time] In each of Examples and Comparative Examples, the time from the start of depressurization until the stirring torque reached a predetermined value was confirmed. The results are shown in Table 1. Moreover, the torque value displayed when the target melt viscosity becomes a predetermined value. The target melt viscosity of the polymers of Examples 1 to 4, Comparative Examples 1 and 2 is 15 Pa‧s at a cylinder temperature of 360°C and a shear rate of 1000 sec ^-1 . In addition, the melt viscosity is measured by a capillary rheometer (Capilograph 1D manufactured by Toyo Seiki Co., Ltd.: piston diameter 10 mm). At the above cylinder temperature and shear speed, the melt viscosity shown is based on ISO 11443 Perform the measurement. An orifice with an inner diameter of 0.5 mm and a length of 30 mm was used for the measurement.

[Melting point] In each of the examples and comparative examples, a differential scanning calorimeter (DSC, manufactured by Hitachi High-Tech Science Corporation.) was used to measure the observation of the liquid crystalline resin when it was heated from room temperature at a heating rate of 20°C/min. The endothermic peak temperature (Tm1). Next, the temperature was maintained at (Tm1+40)°C for 2 minutes. Furthermore, after temporarily cooling to room temperature at a temperature decrease rate of 20°C/minute, the temperature was again measured at the endothermic peak temperature (Tm2) observed during heating at a temperature increase rate of 20°C/minute as the melting point.

[Amount of carbon dioxide produced] In each of the Examples and Comparative Examples, a thermogravimetric measurement device (TGA, manufactured by TA Instruments) was used, and at a temperature of 25°C higher than the melting point of the liquid crystalline resin (Tm2+25) under a nitrogen flow of 10 mg of the liquid crystalline resin. °C), the amount of weight loss when maintained for 30 minutes is measured, and this is evaluated as the amount of carbon dioxide gas generated.

。[Table 1]

.

As can be seen from Table 1, in Examples 1 to 4, after the start of decompression, the time to reach the predetermined torque is short, and the amount of carbon dioxide gas generated is small. That is, in Examples 1 to 4, it is shown that both the reduction of the generation of carbonic acid gas and the increase of the polycondensation speed can be achieved. In contrast, in Comparative Examples 1 to 2, the result was that it was impossible to satisfy both the reduction of carbon dioxide gas generation and the increase of the polycondensation rate.

no.

no.

Claims (4)

A method for producing a liquid crystalline resin is a method for producing a liquid crystalline resin by reacting a raw material monomer containing at least one selected from the group consisting of aromatic hydroxycarboxylic acids and polymerizable derivatives thereof, It includes the step of performing polycondensation of the above-mentioned raw material monomer in the presence of an acidic compound having a B-O (boron-oxygen) bond or a compound that can produce the above-mentioned acidic compound in the reaction system. The method for manufacturing a liquid crystalline resin as described in item 1 of the patent application scope, wherein before the polycondensation step, the raw material monomer further includes an acidic compound having a BO (boron-oxygen) bond, or a reaction system The step of acylating it in the presence of a compound that can produce the above compound. The method for producing a liquid crystalline resin according to claim 1 or claim 2, wherein in the polycondensation step, a compound having a tertiary amine or an oxide thereof is further present. The method for producing a liquid crystalline resin according to any one of the first to third patent applications, wherein the acidic compound having a BO (boron-oxygen) bond is at least one electron in an aryl group An attractive group of arylboronic acid (arylboronic acid).