WO2021241607A1

WO2021241607A1 - Method for producing liquid crystalline resin

Info

Publication number: WO2021241607A1
Application number: PCT/JP2021/019894
Authority: WO
Inventors: 浩一齊藤; 智之多田; 桂一加中
Original assignee: ポリプラスチックス株式会社
Priority date: 2020-05-29
Filing date: 2021-05-26
Publication date: 2021-12-02
Also published as: JPWO2021241607A1; JP7072733B1; TW202206490A

Abstract

[Problem] To provide a method for producing a liquid crystalline resin, said method using a salt of at least one acidic compound that has an acid dissociation constant pKa of 1 or less and at least one organic base compound that has one or more nitrogen atoms. The first embodiment of the present invention further addresses the problem of providing a method for producing a liquid crystalline resin, said method being capable of increasing the reaction rate, while suppressing the generation of a gas during melting of a liquid crystalline resin and enabling the achievement of a liquid crystalline resin that has high brightness. The second embodiment of the present invention further addresses the problem of providing a method by which a liquid crystalline resin is produced at a lower cost than ever before. [Solution] A method for producing a liquid crystalline resin, said method comprising a process wherein a starting material monomer is reacted in the presence of a salt of at least one acidic compound that has an acid dissociation constant pKa of 1 or less and at least one organic base compound that has one or more nitrogen atoms.

Description

Liquid crystal resin manufacturing method

The present invention relates to a method for producing a liquid crystal resin.

Liquid crystal resins represented by liquid crystal polyester resins and liquid crystal polyester amide resins are widely used in various fields because they are excellent in high fluidity, low burr property, reflow resistance and the like. The liquid crystal resin is obtained by appropriately combining and selecting raw material monomers such as aromatic hydroxycarboxylic acid, aromatic dicarboxylic acid, and aromatic diol so as to obtain a liquid crystal resin having desired physical properties, and polycondensing them. Be done. In practice, it is common that a mixture of raw material monomers is pre-acylated with an acylating agent (acetic anhydride or the like), and then the acylated raw material monomers are subjected to a polycondensation reaction (for example, Patent Documents 1 and 2).
Japanese Unexamined Patent Publication No. 2020-19866 International Publication No. 2020/026746

In the production of the liquid crystal resin, various catalysts such as potassium acetate are used in order to improve the rate of the polycondensation reaction. However, the use of potassium acetate tends to generate more gas during the reaction. This is because the presence of potassium acetate, which is a basic substance, activates the carboxy group (-COOH) at the end of the liquid crystal resin by becoming a carboxylic acid ion (-COO-), which facilitates desorption as carbonic acid gas. it is conceivable that. On the other hand, the polycondensation reaction may be carried out without a catalyst only in consideration of suppressing the generation of carbon dioxide gas, but in the case of no catalyst, the polycondensation rate cannot be improved as a matter of course.
As a technique for achieving both reduction of gas generation and improvement of polycondensation rate, there is a technique of performing a polycondensation reaction under acidic conditions using an acid catalyst (for example, Patent Documents 1 and 2).

In the process of diligent research to further improve the conventional technique, the present inventor conducts a polycondensation reaction with at least one acidic compound having an acid dissociation constant pKa of 1 or less and at least one organic having one or more nitrogen atoms. It has been found that the reduction of gas generation and the improvement of the polycondensation rate can be achieved at the same time and the decrease in the brightness of the liquid crystal resin can be suppressed by carrying out in the presence of a salt with the basic compound.

Further, as a conventional acylating agent, an acid anhydride such as acetic anhydride is generally used (for example, Patent Documents 1 and 2). However, since acid anhydrides are expensive, there is a demand for a method for producing a liquid crystal resin at a lower cost. For example, a carboxylic acid such as acetic acid is generally cheaper than an acid anhydride, and if it can be used as an acylating agent, a liquid crystal resin can be produced at low cost. However, when a carboxylic acid is used, the acylation reaction of the raw material monomer does not proceed sufficiently.
The present inventor performs the acylation reaction in the presence of a salt of at least one acidic compound having an acid dissociation constant pKa of 1 or less and at least one organic base compound having one or more nitrogen atoms. It has been found that the acylation reaction rate of the raw material monomer can be increased even when a carboxylic acid is used as the agent.

A common object of the present invention is to provide a method for producing a liquid crystal resin using a salt of at least one acidic compound having an acid dissociation constant pKa of 1 or less and at least one organic base compound having one or more nitrogen atoms. That is.
A further problem in the first aspect of the present invention is the production of a liquid crystal resin capable of increasing the reaction rate, suppressing the generation of gas when the liquid crystal resin is melted, and obtaining a liquid crystal resin having high brightness. To provide a method.
A further object of the second aspect of the present invention is to provide a method for producing a liquid crystal resin at a lower cost than before.

The present invention relates to the following.
[1] A liquid crystal resin comprising reacting a raw material monomer in the presence of a salt of at least one acidic compound having an acid dissociation constant pKa of 1 or less and at least one organic base compound having one or more nitrogen atoms. Manufacturing method.
[2] Acylation comprises (A) acylating the raw material monomer, (B) polycondensing the acylated raw material monomer, and (A) acidifying the raw material monomer and the carboxylic acid. A method for producing a liquid crystal resin, which comprises reacting at least one acidic compound having a dissociation constant pKa of 1 or less with at least one organic base compound having 1 or more nitrogen atoms in the presence of a salt (a1).
[3] Acylation (A) causes the reaction of the raw material monomer and the carboxylic acid (a1), and then the acid anhydride is added to the reaction solution to react the unreacted raw material monomer with the acid anhydride. The method for producing a liquid crystal resin according to [2], which comprises the same (a2).
[4] The method for producing a liquid crystal resin according to [2] or [3], wherein the polycondensation (B) comprises polycondensing the acylated raw material monomer in the presence of the salt.
[5] Any of [2] to [4], wherein the amount of the carboxylic acid added in the reaction of the raw material monomer and the carboxylic acid (a1) is 0.01 to 1000 equivalents with respect to the hydroxyl group of the raw material monomer. The method for producing a liquid crystal resin described in Crab.
[6] The amount of the acid anhydride added in (a2) of adding the acid anhydride to react the unreacted raw material monomer with the acid anhydride is 0.01 to 0. The method for producing a liquid crystal resin according to any one of [3] to [5], which is 99 equivalents.
[7] The method for producing a liquid crystal resin according to any one of [1] to [6], wherein the acidic compound constituting the salt has a sulfonic acid group.
[8] The method for producing a liquid crystal resin according to any one of [1] to [7], wherein the organic base compound constituting the salt has an amino group.
[9] The method for producing a liquid crystal resin according to any one of [1] to [8], wherein the acid dissociation constant pKa of the acidic compound constituting the salt is 0.65 or less.
[10] The method for producing a liquid crystal resin according to any one of [1] to [9], wherein the acid dissociation constant pKa of the conjugate acid of the organic base compound constituting the salt is less than 13.0.
[11] The method for producing a liquid crystal resin according to any one of [1] to [10], wherein the acidic compound constituting the salt contains a halogenated alkyl sulfonic acid.
[12] The method for producing a liquid crystal resin according to any one of [1] to [11], wherein the organic base compound constituting the salt contains a halogenated aromatic amine.

The first aspect of the present invention relates to the following.
[1] A liquid crystal resin comprising reacting a raw material monomer in the presence of a salt of at least one acidic compound having an acid dissociation constant pKa of 1 or less and at least one organic base compound having one or more nitrogen atoms. Manufacturing method.
[2] The method for producing a liquid crystal resin according to [1], wherein the acidic compound constituting the salt has a sulfonic acid group.
[3] The method for producing a liquid crystal resin according to [1] or [2], wherein the organic base compound constituting the salt has an amino group.
[4] The method for producing a liquid crystal resin according to any one of [1] to [3], wherein the acid dissociation constant pKa of the acidic compound constituting the salt is 0.65 or less.
[5] The method for producing a liquid crystal resin according to any one of [1] to [4], wherein the acid dissociation constant pKa of the conjugate acid of the organic base compound constituting the salt is less than 13.0.
[6] The method for producing a liquid crystal resin according to any one of [1] to [5], wherein the acidic compound constituting the salt contains a halogenated alkyl sulfonic acid.
[7] The method for producing a liquid crystal resin according to any one of [1] to [6], wherein the organic base compound constituting the salt contains a halogenated aromatic amine.

The second aspect of the present invention relates to the following.
[1] Acylation comprises (A) acylating the raw material monomer, (B) polycondensing the acylated raw material monomer, and (A) acidifying the raw material monomer and the carboxylic acid. A method for producing a liquid crystal resin, which comprises reacting at least one acidic compound having a dissociation constant pKa of 1 or less with at least one organic base compound having 1 or more nitrogen atoms in the presence of a salt (a1).
[2] Acylation (A) causes the reaction of the raw material monomer and the carboxylic acid (a1), and then the acid anhydride is added to the reaction solution to react the unreacted raw material monomer with the acid anhydride. The method for producing a liquid crystal resin according to [1], which comprises the same (a2).
[3] The method for producing a liquid crystal resin according to [1] or [2], wherein the polycondensation (B) comprises polycondensing the acylated raw material monomer in the presence of the salt.
[4] Any of [1] to [3], wherein the amount of the carboxylic acid added in the reaction of the raw material monomer and the carboxylic acid (a1) is 0.01 to 1000 equivalents with respect to the hydroxyl group of the raw material monomer. The method for producing a liquid crystal resin described in Crab.
[5] The amount of the acid anhydride added in (a2) of adding the acid anhydride and reacting the unreacted raw material monomer with the acid anhydride is 0.01 to 0. The method for producing a liquid crystal resin according to any one of [2] to [4], which is 99 equivalents.
[6] The method for producing a liquid crystal resin according to any one of [1] to [5], wherein the acidic compound constituting the salt has a sulfonic acid group.
[7] The method for producing a liquid crystal resin according to any one of [1] to [6], wherein the organic base compound constituting the salt has an amino group.
[8] The method for producing a liquid crystal resin according to any one of [1] to [7], wherein the acid dissociation constant pKa of the acidic compound constituting the salt is 0.65 or less.
[9] The method for producing a liquid crystal resin according to any one of [1] to [8], wherein the acid dissociation constant pKa of the conjugate acid of the organic base compound constituting the salt is less than 13.0.
[10] The method for producing a liquid crystal resin according to any one of [1] to [9], wherein the acidic compound constituting the salt contains a halogenated alkyl sulfonic acid.
[11] The method for producing a liquid crystal resin according to any one of [1] to [10], wherein the organic base compound constituting the salt contains a halogenated aromatic amine.

According to the present invention, it is possible to provide a method for producing a liquid crystal resin using a salt of at least one acidic compound having an acid dissociation constant pKa of 1 or less and at least one organic base compound having one or more nitrogen atoms. can.
According to the first aspect of the present invention, a method for producing a liquid crystal resin, which can increase the reaction rate, suppress the generation of gas when the liquid crystal resin is melted, and can obtain a liquid crystal resin having high brightness. Can be provided.
According to the second aspect of the present invention, it is possible to provide a method for producing a liquid crystal resin at a lower cost than before.

Hereinafter, an embodiment of the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be carried out with appropriate modifications as long as the effects of the present invention are not impaired.

In the method for producing a liquid crystal resin according to an embodiment, the raw material monomer is in the presence of a salt of at least one acidic compound having an acid dissociation constant pKa of 1 or less and at least one organic base compound having one or more nitrogen atoms. Including reacting with. More specifically, as described in Examples described later, the method for producing a liquid crystal resin according to an embodiment uses a raw material monomer, at least one acidic compound having an acid dissociation constant pKa of 1 or less, and a nitrogen atom. It comprises performing an acylation reaction and / or a polycondensation reaction in the presence of a salt with at least one organic base compound having one or more.
In the first embodiment, particularly the polycondensation reaction (preferably the acylation reaction and the polycondensation reaction), at least one acidic compound having an acid dissociation constant pKa of 1 or less and at least one organic base having one or more nitrogen atoms. It describes what to do in the presence of a salt with the compound.
Then, in the second embodiment, particularly the acylation reaction (preferably the acylation reaction and the polycondensation reaction), at least one acidic compound having an acid dissociation constant pKa of 1 or less and at least one organic having one or more nitrogen atoms. It describes what to do in the presence of a salt with a base compound.
If the contents are duplicated in the first embodiment and the second embodiment, the description may be omitted.

1st Embodiment [Manufacturing method of liquid crystal resin]
In the method for producing a liquid crystal resin according to the present embodiment, the raw material monomer is in the presence of a salt of at least one acidic compound having an acid dissociation constant pKa of 1 or less and at least one organic base compound having one or more nitrogen atoms. Including reacting with.
By polycondensing the raw material monomer in the presence of a salt of the acidic compound and the organic base compound, the polycondensation rate can be increased and gas such as carbon dioxide is generated when the liquid crystal resin is melted. Can be further reduced than before. In addition, it is possible to prevent the brightness of the liquid crystal resin from decreasing (for example, turning black). Since the polycondensation rate can be increased, the liquid crystal resin can be produced in a shorter time than before, and the cost can be reduced. Since the generation of gas when the liquid crystal resin is melted can be further reduced, the swelling (blister) of the molded product due to the generated gas can be suppressed. Since it is possible to prevent a decrease in the brightness of the liquid crystal resin, it is possible to produce a liquid crystal resin that gives a molded product having an excellent appearance.

"Liquid crystal" means having a property of being able to form an optically anisotropic molten phase. The properties of the anisotropic molten phase can be confirmed by a conventional polarization inspection method using an orthogonal polarizing element. More specifically, the confirmation of the anisotropic molten phase can be carried out by observing the molten sample placed on the Leitz hot stage at a magnification of 40 times under a nitrogen atmosphere using a Leitz polarizing microscope. A resin having liquid crystallinity normally transmits polarized light even in a molten stationary state when inspected between orthogonal polarizing elements, and exhibits optical anisotropy.

(Raw material monomer)
The raw material monomer preferably 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 derivative are not particularly limited, and are, for example, p-hydroxybenzoic acid (4-hydroxybenzoic acid: HBA), 6-hydroxy-2-naphthoic acid, m-hydroxybenzoic acid. , 6-Hydroxy-3-naphthoic acid, 6-hydroxy-4-naphthoic acid, 4-hydroxy-4'-carboxydiphenyl ether, 2,6-dichloro-p-hydroxybenzoic acid, 2-chloro-p-hydroxybenzoic acid , 2,6-Dimethyl-p-hydroxybenzoic acid, 2,6-difluoro-p-hydroxybenzoic acid, 4-hydroxy-4'-biphenylcarboxylic acid, vanillic acid and the like. At least one compound selected from these can be used. Above all, 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.

The raw material monomer further preferably satisfies the following (1) or (2).
(1) Containing or containing at least one compound selected from the group consisting of aromatic or alicyclic dicarboxylic acids and polymerizable derivatives thereof.
(2) At least one compound selected from the group consisting of aromatic or alicyclic dicarboxylic acids and polymerizable derivatives thereof, and aromatic or alicyclic diols, aromatic or alicyclic hydroxyamines, aromatics or Includes alicyclic diamines and at least one compound selected from the group consisting of polymerizable derivatives thereof.

The aromatic dicarboxylic acid is not particularly limited, and is, for example, terephthalic acid (TA), isophthalic acid (IA), 4,4'-diphenyldicarboxylic acid, 2,6-naphthalenedicarboxylic acid, and the following general formula (I). Examples thereof include compounds represented by.
General formula (I):

(Y:-(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-cyclohexanedicarboxylic acid and 1,3-cyclopentanedicarboxylic acid. The polymerizable derivative is not particularly limited, and examples thereof include an alkyl ester (about 1 to 4 carbon atoms) of the above compound, a halide and the like.

The aromatic diol is not particularly limited, and is, for example, 2,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4,4'-dihydroxybiphenyl (BP), hydroquinone, resorcin, represented by the following general formula (II). Examples thereof include compounds represented by the following general formula (III).

General formula (II):

(X: _{A group selected from alkylene (C 1} to C ₄ ), alkylidene, -O-, -SO-, -SO _2- , -S-, and -CO-).

General formula (III):

The alicyclic diol 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 an alkyl ester (about 1 to 4 carbon atoms) of the above compound, a halide and the like.

The aromatic hydroxyamine is not particularly limited, and examples thereof include p-aminophenol and m-aminophenol. The alicyclic hydroxyamine 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 an alkyl ester (about 1 to 4 carbon atoms) of the above compound, a halide and the like.

Examples of the aromatic diamine include p-phenylenediamine and the like. 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 an alkyl ester (about 1 to 4 carbon atoms) of the above compound, a halide and the like.

Specific combinations of raw material monomers include, for example,
(I) (a) Containing or containing at least one compound selected from the group consisting of aromatic hydroxycarboxylic acids and polymerizable derivatives thereof.
(II) A group consisting of at least one compound selected from the group consisting of (a) aromatic hydroxycarboxylic acid and a polymerizable derivative thereof, and (b) a group consisting of an aromatic or alicyclic dicarboxylic acid and a polymerizable derivative thereof. At least one compound selected from, and (c) at least one compound selected from the group consisting of aromatic or alicyclic diols, aromatic hydroxyamines, aromatic diamines, and polymerizable derivatives thereof. Can be a combination including. Further, a molecular weight adjusting agent may be used in combination with the above-mentioned constituent components, if necessary.

(Polycondensation reaction step)
In the polycondensation reaction step, the above-mentioned raw material monomer is preferably subjected to an acylation reaction described later, and then referred to as at least one acidic compound having an acid dissociation constant pKa of 1 or less (hereinafter, also simply referred to as “acid compound”). A polycondensation reaction is carried out by melt polymerization in the presence of a salt with at least one organic base compound having one or more nitrogen atoms (hereinafter, also simply referred to as “organic base compound”). The salt of the acidic compound and the organic base compound acts as a catalyst for the polycondensation reaction.

The salt of the acidic compound and the organic base compound is composed of an anion of the acidic compound and a cation of the organic base compound. As the salt of the acidic compound and the organic base compound, in addition to using the salt itself, the salt may be formed by coexisting the acidic compound and the organic base compound in the reaction system. The acidic compound and the organic base compound can form a salt by an acid-base reaction in the reaction system.

The acidic compound (anionic component) has an acid dissociation constant pKa of 1 or less, preferably 0.65 or less, more preferably -14.0 to 0.65, and further preferably -14.0 to-. It is 2.0. If the acid dissociation constant pKa of the acidic compound exceeds 1, the effect of improving the polycondensation reaction rate may decrease, which is not preferable. The above pKa means pKa in an aqueous solution at 25 ° C.

The acidic compounds, organic acid compounds include, for example, a sulfonic acid group (-SO 3 _H), a sulfonyl group (-SO 2 _-) organic acid compounds having at least one one or more functional groups selected from the listed , One or more selected from these can be used. That is, the salt preferably contains one or more anion components selected from sulfonic acid anions and sulfonylimide anions. In one embodiment, the acidic compound has a sulfonic acid group.

The acidic compound preferably contains a sulfonic acid in terms of acidity or ease of handling at room temperature. Examples of the sulfonic acid include an alkyl sulfonic acid which may have a substituent and an aryl sulfonic acid which may have a substituent. Examples of the alkyl sulfonic acid include methane sulfonic acid (pKa: -2.6) and the like. Examples of the aryl sulfonic acid include benzene sulfonic acid (pKa: 0.7), p-toluene sulfonic acid (pKa: -2.8), naphthalene sulfonic acid (pKa: 0.17), and dodecylbenzene sulfonic acid (pKa). : -0.45), 1.3-benzenedisulfonic acid (pKa: -1.4) and the like.
The acidic compound preferably contains a halogenated sulfonic acid and / or a halogenated alkyl sulfonic acid in terms of adjusting the acidity or lowering the boiling point. Examples of the halogenated sulfonic acid and / or the halogenated alkyl sulfonic acid include fluorosulfonic acid (pKa: -10), difluoromethanesulfonic acid (pKa: -2.0), and trifluoromethanesulfonic acid (pKa: -14.0). , Perfluorobutane sulfonic acid (pKa: -13.2), perfluorohexane sulfonic acid (pKa: -12.3) and the like, and it is preferable to include one or more selected from these. Of these, trifluoromethanesulfonic acid is most preferable.
In one embodiment, the acidic compound comprises a halogenated alkyl sulfonic acid.

Alternatively, in the present embodiment, in addition to using the acidic compound as it is (or using the salt of the acidic compound and an organic base compound described later as it is), a compound capable of generating the acidic compound anion in the reaction system. Can be used. By generating the acidic compound in the reaction system, the same effect as the effect when the acidic compound (or the salt of the acidic compound and the organic base compound) can be obtained can be obtained.

Compounds that can generate an organic acid compound having at least one sulfonic acid group in the reaction system include mono, di or trifluoromethanesulfonic acid trimethylsilyl, mono, di or trifluoromethanesulfonic acid tert-butylsilyl, mono, di or trifluo. Examples thereof include lomethanesulfonyl halide and trifluoromethanesulfonic acid metal salt. These compounds can generate mono, di or trifluoromethanesulfonic acid anions in the reaction system due to the presence of carboxylic acid or heating.

The organic base compound is a compound that generates an organic onium cation and has one or more nitrogen atoms. That is, the salt contains at least a nitrogen cation. By reacting the raw material monomer in the presence of a salt of an organic base compound having one or more nitrogen atoms and the above-mentioned acidic compound, surprisingly, not only the reaction rate can be increased, but also gas generation can be further increased. It was found that the reduction can be achieved and the brightness of the liquid crystal resin can be prevented from being lowered.

The organic base compound (cationic component) preferably has an acid dissociation constant pKa of the conjugate acid of less than 13.0, preferably -10.0 to 8.0, in terms of the basicity of the organic base compound. Is more preferable, and −8.0 to 6.0 is even more preferable.
The acid dissociation constant pKa of the conjugate acid of the organic base compound means pKa in an aqueous solution at 25 ° C.

Examples of the organic base compound having one or more nitrogen atoms include alkylamines, aromatic amines, alicyclic amines, nitrogen-containing heterocyclic compounds and the like, which may have a substituent. That is, the salt has an alkylammonium cation that may have a substituent, an aromatic ammonium cation that may have a substituent, an alicyclic ammonium cation that may have a substituent, and a substituent. A nitrogen-containing heterocyclic compound may contain one or more selected from cations.
Examples of the alkylamine include N, N-diisopropylethylamine (acid dissociation constant of conjugated acid pKa: 11.0), trimethylamine (acid dissociation constant of conjugated acid pKa: 9.8), and triethylamine (acid dissociation constant of conjugated acid pKa:: 10.8) and the like.
Examples of the aromatic amine include diphenylamine (acid dissociation constant of conjugated acid pKa: 0.7), aniline (acid dissociation constant of conjugated acid pKa: 4.6), and triphenylamine (acid dissociation constant of conjugated acid pKa: -3). .0) and the like.
Examples of the alicyclic amine include cyclopentylamine (acid dissociation constant of conjugated acid pKa: 10.7), cyclohexylamine (acid dissociation constant of conjugated acid pKa: 10.7) and the like.
Examples of the nitrogen-containing heterocyclic compound include 2,5-dimethylpyrrolidine (acid dissociation constant of conjugated acid pKa: 11.4), N, N-dimethylpiperazine (acid dissociation constant of conjugated acid pKa: 4.6), N-. Methylmorpholin (acid dissociation constant of conjugated acid pKa: 7.38), N-acetylmorpholin (acid dissociation constant of conjugated acid pKa: -0.7), dimethylaminopyridine-N-oxide / hydrate (of conjugated acid) Acid dissociation constant pKa: 3.9), N, N-dimethyl-4-aminopyridine (DMAP, acid dissociation constant of conjugated acid pKa: 9.7), 4-methoxypyridine-N-oxide (MPO, (conjugated acid) Acid dissociation constant pKa: 2.3) and the like.
The organic base compound preferably has an amino group in terms of basicity, and more preferably contains a halogenated aromatic amine in terms of adjusting the acid dissociation constant pKa of the conjugate acid or lowering the boiling point. Examples of the halogenated aromatic amine include pentafluoroaniline (acid dissociation constant of conjugated acid pKa: −0.16), 2-fluoropyridine (acid dissociation constant of conjugated acid pKa: −0.44) and the like.
The organic base compound preferably contains one or more selected from diphenylamine and pentafluoroaniline. That is, the salt preferably contains one or more selected from a diphenylammonium cation, a pentafluoroanillium cation, and a 2-fluorodimethylaminopyridinium cation.

Specific examples of the salt of the acidic compound and the organic base compound include, for example, the following compounds:

The salts of the acidic compound and the organic base compound are the above-mentioned (pentafluorophenyl) ammonium trifluoromethanesulfonate (PFBAT), (pentafluorophenyl) ammonium bis (trifluoromethanesulfonyl) imide and diphenylammonium trifluoromethanesulfonate (DPAT). It is preferable to include 1 or more selected from.
It is preferable to use the above-mentioned salt of the acidic compound and the organic base compound as a catalyst in the polycondensation reaction step.

(Amount of salt added between acidic compound and organic base compound)
In the present embodiment, the amount of the salt added to the acidic compound and the organic base compound is not particularly limited as long as it does not adversely affect acylation or polycondensation, but is generally based on the theoretical yield of the liquid liquid resin obtained. It is preferably 50 to 5000 ppm, more preferably 100 to 3000 ppm.

The amount of the acidic compound and the organic base compound added when the salt of the acidic compound and the organic base compound is generated by coexisting the acidic compound and the organic base compound in the reaction system is, for example, the acidic compound (or in the reaction system). The addition amount of (a compound capable of generating an acidic compound) is [(molecular weight of acidic compound / molecular weight of produced salt) × 50] to [(molecular weight of acidic compound / molecular weight of produced salt) × 5000] ppm. Is preferable, and is more preferably [(molecular weight of acidic compound / molecular weight of produced salt) × 100] to [(molecular weight of acidic compound / molecular weight of produced salt) × 3000] ppm. The amount of the organic base compound added is preferably 0.8 to 1.2 equivalents with respect to the acid moiety of the acidic compound, and 0.9 to 1 with respect to the acid moiety of the acidic compound. More preferably, it is 1 equivalent.

The temperature for polycondensation is preferably, for example, 200 to 400 ° C, more preferably 240 to 380 ° C. The reaction time is not particularly limited, and is preferably, for example, 4 to 14 hours, more preferably 6 to 10 hours.

In the production method of the present embodiment, the number average degree of polymerization at 260 ° C. is preferably 2.5 or more, and more preferably 3.0 or more. When the number average degree of polymerization at 260 ° C. is 2.5 or more, the reaction rate (polycondensation rate) is increased and the liquid crystal resin can be produced in a short time. The number average degree of polymerization is a value calculated from the amount of distillate of acetic acid produced as a by-product in the polycondensation reaction process.

(Acylation reaction step)
In the production method of the present embodiment, a step of acylating the raw material monomer with an acylating agent can be provided before the polycondensation reaction described above. The acylation is characterized in that a liquid crystal resin is produced in a shorter time, and the above-mentioned catalyst (at least one acidic compound having an acid dissociation constant pKa of 1 or less and at least one organic base compound having one or more nitrogen atoms) is used. It is preferable to carry out in the presence of (salt) with.

Examples of the acylating agent include acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride, valeric acid anhydride, pivalic anhydride, 2-ethylhexanoic acid anhydride, monochloroacetic anhydride, dichloroacetic acid anhydride, trichloracetic anhydride, and monobromoacetic acid anhydride. , Acetic anhydride, tribromoacetic anhydride, monofluoroacetic anhydride, difluoroacetic anhydride, trifluoroacetic acid anhydride, glutaric anhydride, maleic anhydride, succinic anhydride, β-bromopropionic anhydride and the like, but are particularly limited. Not a thing. At least one selected from these can be used. Suitable examples from the viewpoint of price and handleability include acetic anhydride, propionic anhydride, butyric anhydride, and carboxylic acid anhydride such as isobutyric anhydride. Of these, acetic anhydride is preferred in terms of availability. The amount of the acylating agent used is preferably 1.0 to 1.1 equivalents, preferably 1.01 to 1.05 equivalents, based on the total amount of hydroxyl groups of the substance used in the reaction, in terms of ease of reaction control. Is more preferable.

Acylation can be performed by a known method. For example, the raw material monomer is mixed with an acylating agent and heated in a temperature range of 120 to 160 ° C. for about 0.5 to 5 hours for an acylation reaction to obtain a reaction product containing an acylated product.

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

For solid phase polymerization, a conventionally known method can be used. For example, it can be carried out by heating under reduced pressure or vacuum in an inert gas stream such as nitrogen gas at a temperature 10 to 120 ° C. lower than the liquid crystal forming temperature of the raw material resin. Since the melting point of the liquid crystal resin increases as the solid phase polymerization progresses, it is possible to carry out the solid phase polymerization at a temperature equal to or higher than the original melting point of the raw material resin. The solid phase polymerization may be carried out at a constant temperature or may be gradually heated to a high temperature. The heating method is not particularly limited, and microwave heating, heater heating, or the like can be used.

[Liquid crystal resin]
The liquid crystal resin obtained by the production method of the present embodiment preferably contains at least one selected from liquid crystal polyester and liquid crystal polyester amide. The liquid crystal polyester and the liquid crystal polyester amide are not particularly limited, but are preferably aromatic polyester or aromatic polyester amide, and are repeating units derived from one or more of aromatic hydroxycarboxylic acid and its derivatives. It is particularly preferable that it is an aromatic polyester or an aromatic polyester amide having the above as a constituent component. Further, it may be a polyester which partially contains an aromatic polyester or an aromatic polyester amide in the same molecular chain.

More specifically, as an aromatic polyester or an aromatic polyester amide,
(1) Polyester mainly composed of (a) one or more kinds of aromatic hydroxycarboxylic acids and derivatives thereof;
(2) Mainly (a) one or more of aromatic hydroxycarboxylic acids and derivatives thereof, and (b) one or more of aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and their derivatives. Polyester consisting of;
(3) Mainly (a) one or more of aromatic hydroxycarboxylic acids and derivatives thereof, and (b) one or more of aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and derivatives thereof. , (C) Aromatic diols, alicyclic diols, aliphatic diols, and polyesters consisting of one or more of their derivatives;
(4) Mainly (a) one or more kinds of aromatic hydroxycarboxylic acids and derivatives thereof, and (c1) one or more kinds of aromatic hydroxyamines, aromatic diamines, and derivatives thereof, (c1). c2) A polyester amide consisting of an aromatic dicarboxylic acid, an alicyclic dicarboxylic acid, and one or more of their derivatives;
(5) Mainly (a) one or more kinds of aromatic hydroxycarboxylic acids and their derivatives, and (b) one or more kinds of aromatic dicarboxylic acids, alicyclic dicarboxylic acids, and their derivatives. , (C1) one or more of aromatic hydroxyamines, aromatic diamines, and their derivatives, and (c2) one or more of aromatic diols, alicyclic diols, and their derivatives. Examples thereof include a polyester amide composed of.

The molecular weight (number average molecular weight Mn) of the liquid crystal resin is not particularly limited, and the resin obtained in the melt polymerization step (polycondensation reaction step) is preferably 10,000 to 100,000, preferably 15,000 to 80,000. Is more preferable. The resin obtained in the solid phase polymerization step is preferably 12,000 to 120,000, more preferably 15,000 to 100,000. The number average molecular weight Mn can be measured by gel permeation chromatography.

The melting point of the liquid crystal resin is not particularly limited and can be 250 to 380 ° C. The melt viscosity of the liquid crystal resin is not particularly limited, and the resin obtained by melt polymerization (polycondensation reaction step) has a cylinder temperature 10 to 30 ° C. higher than the melting point of the liquid crystal resin and a shear rate of 1000 sec ^-1 . The measured melt viscosity is preferably 5 Pa · s or more and 150 Pa · s or less, and more preferably 10 Pa · s or more and 100 Pa · s or less. Further, the resin obtained by performing the solid phase polymerization step has a melt viscosity of 5 Pa · s or more and 200 Pa · s or less measured at a cylinder temperature 10 to 30 ° C. higher than the melting point of the liquid crystal resin and a shear rate of 1000 sec ^-1. It is preferable, and more preferably, it is 10 Pa · s or more and 150 Pa · s or less.

"Cylinder temperature 10 to 30 ° C higher than the melting point of the liquid crystal resin" means the cylinder temperature at which the liquid crystal resin can be melted to the extent that the melt viscosity can be measured, and is several degrees Celsius higher than the melting point. Whether to set the cylinder temperature high depends on the type of raw material resin in the range of 10 to 30 ° C. The liquid crystal resin can be in the form of a powder or granular material mixture, or can be in the form of a melt mixture (melt kneaded product) such as pellets.

For the liquid crystal resin, the amount of weight loss when 10 mg of the liquid crystal resin is held at a temperature 25 ° C higher than the melting point of the liquid crystal resin (Tm2 + 25 ° C) for 30 minutes under a nitrogen stream using a thermal weight measuring device. (Mass%) is preferably 1.2% by mass or less, more preferably 1.0% by mass or less, and further preferably 0.8% by mass or less. When the weight reduction amount (mass%) is 1.2% by mass or less, the amount of gas generated at the time of melting is small, so that the swelling (blister) of the molded product due to the generated gas can be suppressed.

^{The liquid crystal resin preferably has an L *} value of 70 or more, preferably 80 or more, of the powdery granular liquid crystal resin (size: 100 to 200 μm) measured by a spectrocolorimeter so as not to impair the appearance of the molded product. Is more preferable.

Second Embodiment In the second embodiment, particularly in the acylation reaction step, in the presence of a salt of at least one acidic compound having an acid dissociation constant pKa of 1 or less and at least one organic base compound having one or more nitrogen atoms. It is essential to do it in. The polycondensation reaction step is also preferably carried out in the presence of a salt of at least one acidic compound having an acid dissociation constant pKa of 1 or less and at least one organic base compound having 1 or more nitrogen atoms.

[Manufacturing method of liquid crystal resin]
The method for producing a liquid crystal resin according to the present embodiment includes (A) acylating a raw material monomer, (B) polycondensing the acylated raw material monomer, and (A) acylating. The reaction of the raw material monomer and the carboxylic acid in the presence of a salt of at least one acidic compound having an acid dissociation constant pKa of 1 or less and at least one organic base compound having one or more nitrogen atoms (a1). include.
"Liquid crystallinity" is as described in the first embodiment. Since the raw material monomer is the same as that in the first embodiment, the description thereof is omitted here.

(Acylation reaction step (A))
In the production method of the present embodiment, a step of acylating the raw material monomer is provided before the polycondensation reaction step of polycondensing the raw material monomer.
In the acylation reaction step (A), the raw material monomer and the carboxylic acid have at least one acidic compound having an acid dissociation constant pKa of 1 or less (hereinafter, also simply referred to as “acidic compound”) and one or more nitrogen atoms. It comprises a step (a1) of reacting with at least one organic base compound (hereinafter, also simply referred to as “organic base compound”) in the presence of a salt (hereinafter, also simply referred to as “step (a1)”).
Surprisingly, acetic acid, which was conventionally considered to be unusable as an acylating agent, because the acylation reaction step (A) includes the step (a1) of using the salt of the acidic compound and the organic base compound described above. It was found that the acylation reaction rate of the raw material monomer can be increased even when a carboxylic acid such as the above is used. As a result, at least a part of the acid anhydride conventionally used as an acylating agent can be changed to a carboxylic acid, and a liquid crystal resin can be produced at a lower cost than the conventional one. The salt of the acidic compound and the organic base compound is considered to have an action as a catalyst for the acylation reaction.

Examples of the carboxylic acid include acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid, pivalic acid, 2-ethylhexanoic acid, monochloroacetic acid, dichloroacetic acid, trichloracetic acid, monobromoacetic acid, dibromoacetic acid, tribromoacetic acid, and monofluoroacetic acid. , Difluoroacetic acid, trifluoroacetic acid, glutaric acid, maleic acid, succinic acid, β-bromopropionic acid and the like, but are not particularly limited. At least one selected from these can be used. From the viewpoint of price and handleability, it is preferable to contain one or more carboxylic acids selected from acetic acid, propionic acid, butyric acid, isobutyric acid and the like. Above all, it is more preferable to contain acetic acid in terms of easy availability.

The amount of the carboxylic acid added in the step (a1) of reacting the raw material monomer with the carboxylic acid is preferably 0.01 to 1000 equivalents, preferably 0.1 to 500 equivalents, relative to the hydroxyl group of the raw material monomer. Is more preferable, and it is further preferable that the amount is 1 to 100 equivalents. By setting the addition amount of the carboxylic acid to 0.01 to 1000 equivalents with respect to the hydroxyl group of the raw material monomer, a liquid crystal resin can be reliably produced at a lower cost.

The acylation method is a known method except that a catalyst described later (a salt of at least one acidic compound having an acid dissociation constant pKa of 1 or less and at least one organic base compound having one or more nitrogen atoms) is used. Can be done based on. For example, the raw material monomer is mixed with a carboxylic acid and a catalyst described later, and heated in a temperature range of 120 to 160 ° C. for about 0.5 to 5 hours for an acylation reaction to obtain a reaction product containing an acylated product. In the step (a1), it is not necessary to use an acid anhydride as an acylating agent. Therefore, the content of acid anhydride in the reaction solution in the step (a1) can be less than 1 equivalent or less than 0.5 equivalent with respect to the hydroxyl group of the raw material monomer, and the structure does not contain acid anhydride. You can also do it.

In one embodiment, after the step (a1) of reacting the raw material monomer with the carboxylic acid, an acid anhydride is added to the reaction solution of the step (a1) to react the unreacted raw material monomer with the acid anhydride. (A2) (hereinafter, also simply referred to as “step (a2)”. ”In step (a2), the unreacted raw material monomer is acylated after the reaction of step (a1).
In this embodiment, the step (a1) of reacting the raw material monomer with the carboxylic acid is referred to as a "first acylation reaction step", and an acid anhydride is added to react the unreacted raw material monomer with the acid anhydride. (A2) can be referred to as a "second acylation reaction step". By providing the second acylation reaction step (step (a2)), the acylation of the raw material monomer can be achieved more efficiently than in the case of only the first acylation reaction step (step (a1)). can. Since the carboxylic acid used in the first acylation reaction step (step (a1)), the amount thereof added, and the acylation method are as described above, the description thereof is omitted here.

As the acid anhydride used in the step (a2), anhydrous acetic acid, anhydrous propionic acid, anhydrous butyric acid, anhydrous isobutyric acid, anhydrous valeric acid, anhydrous pivalic acid, anhydrous 2-ethylhexanoic acid, anhydrous monochloroacetic acid, anhydrous dichloracetic acid, anhydrous Trichloracetic acid, monobromoacetic anhydride, dibromoacetic anhydride, tribromoacetic anhydride, monofluoroacetic anhydride, difluoroacetic anhydride, trifluoroacetic anhydride, glutaric anhydride, maleic anhydride, succinic anhydride, β-bromopropionic anhydride, etc. However, it is not particularly limited. At least one selected from these can be used. From the viewpoint of price and handleability, it is preferable to contain one or more anhydrous carboxylic acids selected from acetic anhydride, propionic anhydride, butyric anhydride, isobutyric anhydride and the like. Above all, it is more preferable to contain acetic anhydride from the viewpoint of easy availability.

The amount of the acid anhydride added in the step (a2) is preferably 0.01 to 0.99 equivalents, more preferably 0.01 to 0.90 equivalents, relative to the hydroxyl group of the raw material monomer. It is more preferably 0.01 to 0.85 equivalent. By setting the addition amount of acid anhydride to 0.01 to 0.99 equivalents with respect to the hydroxyl group of the raw material monomer, the amount is larger than the amount used in the conventional acylation reaction step (for example, 1.00 to 1.10 equivalents). The amount of acid anhydride added can be reduced. As a result, the liquid crystal resin can be manufactured at a lower cost than before.

The acylation in the step (a2) is performed by using a catalyst described later (a salt of at least one acidic compound having an acid dissociation constant pKa of 1 or less and at least one organic base compound having one or more nitrogen atoms). It can be performed based on a known method. For example, an acid anhydride is added to the reaction solution (including the catalyst) of the first acylation reaction step (a1), and the reaction is not reacted by further heating in a temperature range of 120 to 160 ° C. for about 0.5 to 5 hours. The raw material monomer of the above is acylated to obtain a reaction product containing an acylated product.

The acylation reaction rate of the raw material monomer after the step (a1) is preferably 5% or more, and more preferably 10% or more. When the acylation reaction rate is 5% or more, the liquid crystal resin can be produced more efficiently.
The acylation reaction rate of the raw material monomer after the step (a2) is preferably 90% or more, more preferably 95% or more.
The acylation reaction rate shall be a value measured by a ^{nuclear magnetic resonance apparatus (1 H-NMR).}

(catalyst)
The salt of the acidic compound and the organic base compound is composed of an anion of the acidic compound and a cation of the organic base compound. As the salt of the acidic compound and the organic base compound, in addition to using the salt itself, the salt may be formed by coexisting the acidic compound and the organic base compound in the reaction system. The acidic compound and the organic base compound can form a salt by an acid-base reaction in the reaction system.

The acidic compound (anionic component) has an acid dissociation constant pKa of 1 or less, preferably 0.65 or less, more preferably -14.0 to 0.65, and further preferably -14.0 to-. It is 2.0. If the acid dissociation constant pKa of the acidic compound exceeds 1, the effect of improving the acylation reaction rate may decrease, or the effect of improving the polycondensation reaction rate in the polycondensation reaction step described later may decrease, which is not preferable. The above pKa means pKa in an aqueous solution at 25 ° C. Since the example of the acidic compound is the same as the compound described in the first embodiment, the description thereof is omitted here.

Since the examples of the "organic base compound" and the examples of "salt of an acidic compound and an organic base compound" are the same as the compounds and salts described in the first embodiment, the description thereof will be omitted here.
It is preferable to use the above-mentioned salt of the acidic compound and the organic base compound as a catalyst in the acylation reaction step, preferably as a catalyst in the acylation reaction step and the polycondensation reaction step.

(Amount of salt added between acidic compound and organic base compound)
In the present embodiment, the amount of the salt added to the acidic compound and the organic base compound is not particularly limited as long as it does not adversely affect acylation and polycondensation described later, but is generally based on the theoretical yield of a liquid liquid resin obtained. It is preferably 50 to 5000 ppm, and more preferably 100 to 3000 ppm.

The amount of the acidic compound and the organic base compound added when the salt of the acidic compound and the organic base compound is generated by coexisting the acidic compound and the organic base compound in the reaction system is, for example, the acidic compound (or in the reaction system). The addition amount of (a compound capable of generating an acidic compound) is [(molecular weight of acidic compound / molecular weight of produced salt) × 50] to [(molecular weight of acidic compound / molecular weight of produced salt) × 5000] ppm. Is preferable, and is more preferably [(molecular weight of acidic compound / molecular weight of produced salt) × 100] to [(molecular weight of acidic compound / molecular weight of produced salt) × 3000] ppm. The amount of the organic base compound (or the compound capable of generating the organic base compound in the reaction system) is preferably 0.8 to 1.2 equivalents of the base moiety with respect to the acid moiety of the acidic compound, and the acidic compound. It is more preferable that the base moiety is 0.9 to 1.1 equivalents with respect to the acid moiety of.

(Polycondensation reaction step)
In the polycondensation reaction step, the acylated raw material monomer is preferably the catalyst used in the acylation reaction step (A) (at least one acidic compound having an acid dissociation constant pKa of 1 or less and at least one having one or more nitrogen atoms. In the presence of a salt with one organic base compound), a polycondensation reaction is carried out by melt polymerization. By performing the polycondensation reaction in the presence of the catalyst used in the acylation reaction step (A), the liquid crystal resin can be produced in a shorter time, and the generation of gas at the time of melting the liquid crystal resin is further reduced. can. As a result, swelling (blister) of the molded product due to the generated gas can be suppressed).

According to the production method according to the present embodiment, the liquid crystal resin can be produced in high yield even if the amount of acid anhydride is reduced. That is, the liquid crystal resin can be produced in a high yield of 90% or more, 95% or more, or 98% or more at low cost.

(Solid phase polymerization step)
The production method of the present embodiment may further include a step of solid-phase polymerization of the resin obtained in the melt polymerization step (the above-mentioned polycondensation reaction step). By solid-phase polymerization, the molecular weight of the raw material resin can be increased, and a liquid crystal resin having excellent strength and heat resistance can be obtained. Since the method of solid-phase polymerization is the same as that of the first embodiment, the description thereof is omitted here.

[Liquid crystal resin]
The liquid crystal resin obtained by the production method of the present embodiment preferably contains at least one selected from liquid crystal polyester and liquid crystal polyester amide. Examples of the liquid crystal polyester and the liquid crystal polyester amide include the same as those exemplified in the first embodiment. The molecular weight (number average molecular weight Mn) and melting point of the liquid crystal resin are the same as those in the first embodiment.

For the liquid crystal resin, the amount of weight loss when 10 mg of the liquid crystal resin is held at a temperature 25 ° C higher than the melting point of the liquid crystal resin (Tm2 + 25 ° C) for 30 minutes under a nitrogen stream using a thermogravimetric measuring device. (Mass%) is preferably 0.8% by mass or less, and more preferably 0.6% by mass or less. When the weight reduction amount (mass%) is 0.8% by mass or less, the amount of gas generated at the time of melting is small, so that the swelling (blister) of the molded product due to the generated gas can be suppressed.

As described in the first embodiment, a salt of at least one acidic compound having an acid dissociation constant pKa of 1 or less and at least one organic base compound having one or more nitrogen atoms is used as a catalyst in the polycondensation reaction. Therefore, it is possible to increase the reaction rate, suppress the generation of gas when the liquid crystal resin is melted, and obtain a liquid crystal resin having high brightness.
As described in the second embodiment, a salt of at least one acidic compound having an acid dissociation constant pKa of 1 or less and at least one organic base compound having one or more nitrogen atoms is used as a catalyst in the acylation reaction. Therefore, it is possible to provide a method for producing a liquid crystal resin at a lower cost than before.
By using the salt as a catalyst in both the acylation reaction and the polycondensation reaction, both of the above effects can be obtained.

Hereinafter, the present invention will be described in more detail with reference to examples, but the interpretation of the present invention is not limited by these examples.

1st Embodiment [Example 1]
After charging 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 (acyllation reaction step). Then, the temperature is further raised to 360 ° C. over 4.5 hours, and then the pressure is reduced to 10 Torr (that is, 1330 Pa) over 15 minutes while distilling acetic acid, excess acetic anhydride, and other low boiling points. Polycondensation was performed (polycondensation reaction step). After the stirring torque reached a predetermined value, nitrogen was introduced to bring the polymer into a pressurized state from a reduced pressure state through a normal pressure state, and the polymer was discharged from the lower part of the polymerization vessel. Then, the strands were pelletized to obtain liquid crystal resin pellets.
(material)
4-Hydroxybenzoic acid (HBA): 183.7 g (60 mol%)
Terephthalic acid (TA): 51.56 g (14 mol%)
Isophthalic acid (IA): 22.10 g (6 mol%)
4,4'-Dihydroxybiphenyl (BP): 82.56 g (20 mol%)
PFBAT (manufactured by Tokyo Chemical Industry Co., Ltd.): 150 mg (500 ppm)
Acylating agent (acetic anhydride): 226.4 g

[Comparative Example 1]
Liquid crystal resin pellets were obtained in the same manner as in Example 1 except that 45 mg (150 ppm) of potassium acetate (manufactured by Kanto Chemical Co., Inc.) was used instead of PFBAT.

[Comparative Example 2]
Liquid crystal resin pellets were obtained in the same manner as in Example 1 except that PFBAT and other catalysts were not used.

[Comparative Example 3]
Liquid crystal resin pellets were obtained in the same manner as in Example 1 except that 66 mg (220 ppm) of trifluoromethanesulfonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of PFBAT.

[Comparative Example 4]
Liquid crystal resin pellets were obtained in the same manner as in Example 1 except that 81 mg (270 ppm) of pentafluoroaniline (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of PFBAT.

[Comparative Example 5]
Instead of PFBAT, use boric acid (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., pKa: 9.23) at 27 mg (91 ppm) and dimethylaminopyridine-N-oxide / hydrate (manufactured by Tokyo Chemical Industry Co., Ltd.). Liquid crystal resin pellets were obtained in the same manner as in Example 1 except that 61 mg (200 ppm) was used.

[Polycondensation rate (number average degree of polymerization)]
In Examples and Comparative Examples, the weight of acetic acid distilled out from the reaction system when the temperature of the polycondensation reaction step reached 260 ° C. was measured, and the number average degree of polymerization was calculated by the following formula. It can be evaluated that the larger the number average degree of polymerization at 260 ° C., the faster the polycondensation rate (reaction rate). The results are shown in Table 1.
Number average degree of polymerization = 1 / (1- (Amount of distillate acetic acid at 260 ° C.-Theoretical total amount of distillate acetic acid / 2) / (Theoretical total amount of distillate acetic acid / 2))

[Gas generation amount]
The resin pellets obtained in Examples and Comparative Examples were freeze-ground and granulated, and a thermogravimetric measuring device (TGA, manufactured by TA Instrument Co., Ltd.) was used to apply 10 mg of the liquid crystal resin under a nitrogen stream. The weight loss (% by mass) when held for 30 minutes at a temperature 25 ° C. higher than the melting point of the liquid crystal resin (Tm2 + 25 ° C.) was measured and evaluated as the amount of gas generated. The results are shown in Table 1.

[brightness]
The resin pellets obtained in Examples and Comparative Examples were freeze-ground and granulated, and the brightness (L ^* value) was measured with a spectrocolorimeter (SE6000 manufactured by Nippon Denshoku Kogyo Co., Ltd.). The results are shown in Table 1.

As is clear from Table 1, the production method of the examples can achieve both improvement of the reaction rate and suppression of the amount of gas generated when the liquid crystal resin is melted, and can obtain a liquid crystal resin having high brightness. Understandable.
On the other hand, Comparative Example 1 using potassium acetate as a catalyst has the same number average degree of polymerization at 260 ° C. as that of Comparative Example 2 having no catalyst, so that the effect of improving the reaction rate is not observed and the liquid crystal resin has no effect. The amount of gas generated during melting was large.
In Comparative Example 3 in which the acidic compound was used alone as the catalyst, the reaction rate was increased, but the amount of gas generated when the liquid crystal resin was melted was larger than that in the example, and the brightness of the liquid crystal resin was higher. It was low.
In Comparative Example 4 in which the organic base compound was used alone as the catalyst, the amount of gas generated when the liquid crystal resin was melted and the decrease in the brightness of the liquid crystal resin could be suppressed, but the reaction rate could not be improved. could not.
In Comparative Example 5 in which an acidic compound having a pKa greater than 1 and a basic compound were used as catalysts, the amount of gas generated when the liquid crystal resin was melted could be suppressed, but the effect of improving the reaction rate was not observed, and the effect of improving the reaction rate was not observed. The brightness of the liquid crystal resin was low.

2nd Embodiment [Example 2-1]
After charging the following raw materials excluding acetic anhydride 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 (first acylation reaction step). Then, acetic anhydride was added while maintaining the temperature at 140 ° C., and the mixture was reacted for 1 hour (second acylation reaction step). Further, the temperature was raised to 325 ° C. over 3.5 hours, and then the pressure was reduced to 10 Torr (that is, 1330 Pa) over 15 minutes, and polycondensation was performed while distilling acetic acid and other low boiling points (heavy). Condensation reaction step). After the stirring torque reached a predetermined value, nitrogen was introduced to bring the polymer into a pressurized state from a reduced pressure state through a normal pressure state, and the polymer was discharged from the lower part of the polymerization vessel. Then, the strands were pelletized to obtain liquid crystal resin pellets. The yield of the obtained liquid crystal resin was 99%.
(material)
4-Hydroxybenzoic acid (HBA): 37.73 g (73 mol%)
6-Hydroxy-2-naphthoic acid; 19.01 g (27 mol%)
PFBAT (manufactured by Tokyo Chemical Industry Co., Ltd.): 125 mg (2500 ppm)
Acylating agent 1 (acetic acid): 1600 g
Acylating agent 2 (acetic anhydride): 30.94 g

[Comparative Example 2-1]
Liquid crystal resin pellets were obtained in the same manner as in Example 2-1 except that 37 mg (740 ppm) of potassium acetate (manufactured by Kanto Chemical Co., Inc.) was used instead of PFBAT. The yield of the obtained liquid crystal resin was 86%.

[Comparative Example 2-2]
Liquid crystal resin pellets were obtained in the same manner as in Example 2-1 except that PFBAT and other catalysts were not used. The yield of the obtained liquid crystal resin was 89%.

[Acylation (acetylation) reaction rate]
_{0.5 mL of DMSO-d 6} was added to 10 mg of the sample sampled during the acylation reaction in the first acylation reaction step and the second acylation reaction step to dissolve the sample. The obtained solution was transferred to a glass sample tube, ¹ H-NMR measurement was performed with a nuclear magnetic resonance apparatus (NMR, manufactured by Bluker), and the aromatic ring 3-position proton of the unreacted monomer and the acylated (acetylated) monomer were performed. The integrated value of the proton at the 3-position of the aromatic ring was obtained, and the acylation reaction rate was calculated by the following formula.
Acetylation reaction rate (%) = [(integral value of protons of acetylated monomer) / ((integrated value of protons of unreacted monomer) + (integrated value of protons of acetylated monomer))] × 100

[Gas generation amount]
The resin pellets obtained in Examples and Comparative Examples were freeze-ground and granulated, and a thermogravimetric measuring device (TGA, manufactured by TA Instrument Co., Ltd.) was used to apply 10 mg of the liquid crystal resin under a nitrogen stream. The weight loss (% by mass) when held for 30 minutes at a temperature 25 ° C. higher than the melting point of the liquid crystal resin (Tm2 + 25 ° C.) was measured and evaluated as the amount of gas generated. The results are shown in Table 2.

As is clear from Table 2, examples of acylation performed using a salt of at least one acidic compound having an acid dissociation constant pKa of 1 or less and at least one organic base compound having 1 or more nitrogen atoms as a catalyst. In the production method of, the acylation (acetylation) reaction rate of the step (a1) using acetic acid as an acylating agent is high, and the acylation reaction rate of the raw material monomer is reduced even if the amount of anhydrous acetic acid used in the step (a2) is reduced. Was sufficiently enhanced, and a liquid crystal resin could be produced in a high yield. In addition, it was possible to suppress the amount of gas generated during melting.
On the other hand, Comparative Example 2-1 using potassium acetate as a catalyst has a low acylation reaction rate in the step (a1) using acetic acid as an acylating agent, and the amount of acetic anhydride used in the step (a2). When the amount was reduced from the conventional amount, the acylation reaction rate of the raw material monomer was not sufficient, and the liquid crystal resin could not be produced in high yield. In addition, the amount of gas generated when the liquid crystal resin was melted was large.
In Comparative Example 2-2 in which no catalyst was used, although the amount of gas generated when the liquid crystal resin was melted was small, the acylation reaction rate in the step (a1) using acetic anhydride as the acylating agent was high. It was low, and when the amount of acetic anhydride used in the step (a2) was reduced from the conventional amount, the acylation reaction rate of the raw material monomer was not sufficient, and the liquid crystal resin could not be produced in high yield.

Claims

A method for producing a liquid crystal resin, which comprises reacting a raw material monomer in the presence of a salt of at least one acidic compound having an acid dissociation constant pKa of 1 or less and at least one organic base compound having one or more nitrogen atoms. ..
(A) Acylating the raw material monomer,
(B) including polycondensing the acylated raw material monomer.
Acryling (A) is the presence of a salt of the raw material monomer and the carboxylic acid with at least one acidic compound having an acid dissociation constant pKa of 1 or less and at least one organic base compound having one or more nitrogen atoms. A method for producing a liquid crystal resin, which comprises reacting with (a1).
Acylation (A) is the reaction of the raw material monomer with the carboxylic acid (a1), and then the acid anhydride is added to the reaction solution to react the unreacted raw material monomer with the acid anhydride (a1). The method for producing a liquid crystal resin according to claim 2, which comprises a2).
The method for producing a liquid crystal resin according to claim 2 or 3, wherein the polycondensation (B) comprises polycondensing the acylated raw material monomer in the presence of the salt.
The invention according to any one of claims 2 to 4, wherein the amount of the carboxylic acid added in the reaction of the raw material monomer and the carboxylic acid (a1) is 0.01 to 1000 equivalents with respect to the hydroxyl group of the raw material monomer. Method for manufacturing liquid crystal resin.
The amount of acid anhydride added in (a2) of adding acid anhydride to react the unreacted raw material monomer with the acid anhydride is 0.01 to 0.99 equivalents with respect to the hydroxyl group of the raw material monomer. The method for producing a liquid crystal resin according to any one of claims 3 to 5.
The method for producing a liquid crystal resin according to any one of claims 1 to 6, wherein the acidic compound constituting the salt has a sulfonic acid group.
The method for producing a liquid crystal resin according to any one of claims 1 to 7, wherein the organic base compound constituting the salt has an amino group.
The method for producing a liquid crystal resin according to any one of claims 1 to 8, wherein the acid dissociation constant pKa of the acidic compound constituting the salt is 0.65 or less.
The method for producing a liquid crystal resin according to any one of claims 1 to 9, wherein the acid dissociation constant pKa of the conjugate acid of the organic base compound constituting the salt is less than 13.0.
The method for producing a liquid crystal resin according to any one of claims 1 to 10, wherein the acidic compound constituting the salt contains a halogenated alkyl sulfonic acid.
The method for producing a liquid crystal resin according to any one of claims 1 to 11, wherein the organic base compound constituting the salt contains a halogenated aromatic amine.