JP6366133B2 - Method for producing liquid crystalline polyester - Google Patents

Description

  The present invention relates to a method for producing a liquid crystalline polyester.

  Liquid crystalline polyester has excellent mechanical properties and is applied in various fields. The liquid crystalline polyester is generally obtained by acylating a hydroxyl group of a constituent component (such as an aromatic hydroxycarboxylic acid) with a carboxylic anhydride and then performing a polycondensation reaction. Such a series of reactions is conventionally performed by a batch-type production method (see Patent Document 1), but this method often causes variations in quality between batches. .

  In the production of a compound, a continuous production method is known, and specifically, a method using a microreactor can be mentioned (see Patent Document 2). A microreactor is generally one of flow-type reactors, and the width of one flow path is usually 1 μm or more and several mm or less, and the cross-sectional shape thereof is a circle or a polygon (more than a triangle) ) And the like, but the shape is not particularly limited. There are various types of microreactor flow paths, such as a single flow path or a combination of a plurality of flow paths in series or in parallel, and the flow path is appropriately selected depending on the reaction and throughput. According to this method, since the reaction field is small and the surface area per volume is large, the heat exchange rate, the mixing rate, etc. can be increased, the reaction conditions can be adjusted instantaneously, and variations in the quality of the resulting compound can be suppressed ( Non-patent document 1).

Japanese Patent No. 3265662 specification JP 2007-210911 A

Microreactors in Organic Chemistry and Catalysis, Edited by Thomas With, 2013, Wily-VCH

  However, in a continuous production method using a conventional microreactor, since a reaction solvent is used, when the production method is adopted for producing a liquid crystalline polyester, the obtained liquid crystalline polyester causes hydrolysis or the like. There was a possibility. Moreover, when using a reaction solvent, since it is necessary to provide the process of removing a reaction solvent from the obtained reaction material, the method which can manufacture liquid crystalline polyester more efficiently was calculated | required.

  The present invention has been made in view of such circumstances, and in the production of a liquid crystalline polyester, a method for acylating components of the liquid crystalline polyester in a continuous production method without using a reaction solvent. For the purpose of provision.

  The present inventors introduced a carboxylic anhydride and a constituent component, which are raw materials for liquid crystalline polyester, into a flow reactor, and acylated under a solvent-free condition for a short time compared to the conventional method. And the point which can acylate a structural component with a high yield was discovered, and it came to complete this invention.

  (1) A component containing an aromatic carboxylic acid and / or a compound having a hydroxyl group in a flow reactor, and an acylation step of introducing an carboxylic anhydride and performing an acylation reaction under solvent-free conditions, Manufacturing method of liquid crystalline polyester.

  (2) The production method according to (1), wherein the acylation step is performed under non-catalytic conditions.

  According to the present invention, in the method for producing a liquid crystalline polyester, there is provided a method for continuously acylating the constituent components of the liquid crystalline polyester without using a reaction solvent.

  Hereinafter, embodiments of the present invention will be described in detail. In addition, this invention is not limited to the following embodiment.

[Liquid crystal polyester]
The liquid crystalline polyester in the present invention is a melt-processable polyester and exhibits optical anisotropy when melted. The property of melt anisotropy can be confirmed by a conventional polarization inspection method using an orthogonal polarizer. More specifically, the melting anisotropy can be confirmed by melting a sample placed on a hot stage manufactured by Linkham Co., Ltd. using a polarizing microscope manufactured by Olympus and observing it at a magnification of 150 times in a nitrogen atmosphere. The liquid crystalline polymer is optically anisotropic and transmits light when inserted between crossed polarizers. If the sample is optically anisotropic, for example, polarized light is transmitted even in a molten stationary liquid state.

  The liquid crystalline polyester in the present invention can be obtained by acylating the constituent components with carboxylic anhydride and then polycondensing the components.

(Components of liquid crystalline polyester)
The liquid crystalline polyester in the present invention is obtained from a condensation polymerization of an aromatic hydroxycarboxylic acid or a condensation polymerization of an aromatic diol and an aromatic dicarboxylic acid, and from a component containing a compound having an aromatic carboxylic acid and / or a hydroxyl group. Become. Examples of the aromatic carboxylic acid include aromatic dicarboxylic acids and aromatic hydroxycarboxylic acids. Examples of the compound having a hydroxyl group include aromatic diols, alicyclic diols, aliphatic diols, and aromatic hydroxyamines. . In the present invention, among the above components, those having a hydroxyl group are acylated.

Preferred examples of the constituent component (monomer) of the liquid crystalline polyester are:
(I) naphthalene compounds such as 2,6-naphthalenedicarboxylic acid, 2,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene and 6-hydroxy-2-naphthoic acid,
(Ii) Biphenyl compounds such as 4,4′-biphenyldicarboxylic acid, 4,4′-dihydroxybiphenyl, 4-hydroxy-4′-biphenylcarboxylic acid,
(Iii) A compound represented by the following general formula (I), (II) or (III):

(However, X: an alkylene or alkylidene of 1 to 4 carbon _{atoms, -O -, - SO -,} - SO 2 -, - S -, - a group CO- is from chosen, Y :-( _CH 2) n — (N = 1 to 4), —O (CH ₂ ) nO— (n = 1 to 4), —O—, —SO—, —SO ₂ —, —S—, —CO—. ,
(Iv) p-hydroxybenzoic acid (4-hydroxybenzoic acid), terephthalic acid, hydroquinone, p-aminophenol, 4-acetoxyaminophenol, para-substituted benzene compounds such as p-phenylenediamine, and their nuclear substitution Benzene compounds (substituents for nuclear substitution are selected from halogens such as fluorine, chlorine, bromine and iodine, alkyls having 1 to 4 carbon atoms, phenyl and 1-phenylethyl), and (v) isophthalic acid, resorcin, etc. Meta-substituted benzene compounds and their nucleus-substituted benzene compounds (the nucleus-substituted substituent is selected from halogen such as fluorine, chlorine, bromine and iodine, alkyl having 1 to 4 carbon atoms, phenyl and 1-phenylethyl. ).

  Among the above-described constituent components, those containing one or more compounds selected from naphthalene compounds, biphenyl compounds, and para-substituted benzene compounds as essential constituent components are preferable. Of the para-substituted benzene compounds, p-hydroxybenzoic acid, methylhydroquinone and 1-phenylethylhydroquinone are particularly preferred.

(Carboxylic anhydride)
Examples of the carboxylic anhydride in the present invention include lower aliphatic carboxylic acid anhydrides having 10 or less carbon atoms, such as acetic anhydride and propionic anhydride, trifluoroacetic anhydride, etc. preferable. In the present invention, among the above monomers, aromatic diol, alicyclic diol, aliphatic diol, aromatic hydroxycarboxylic acid, hydroxyl group of aromatic hydroxyamine, particularly carboxylic anhydride for acylating phenolic hydroxyl group. The amount used is 1.0 to 1.2 times, more preferably 1.02 to 1.08 times, most preferably 1.02 times the hydroxyl group equivalent of the above compound having a hydroxyl group, particularly an aromatic compound having a phenolic hydroxyl group. The amount may be up to 1.06 times.

[Flow reactor]
In the present invention, the raw materials (components of liquid crystalline polyester, etc.) are introduced into a flow reactor to carry out a synthesis reaction. As a flow reactor in the present invention, a device called a microreactor can be used together with a normal reactor. Specifically, a high-temperature and high-pressure flow cell, a reactant that feeds raw materials (components of liquid crystalline polyester, etc.) Uses a pump equipped with a liquid feed pump, furnace body, reactant introduction pipe (reaction pipe) for introducing the reactant into the furnace body, a drain line for discharging the reaction solution, a cooling flange, and a back pressure valve for setting the pressure. However, the present invention is not limited to this, and the length and diameter of each member constituting the flow reactor can be adjusted as appropriate according to the reactant to be obtained and its throughput.

  In the production method of the present invention, a reaction solvent (supercritical fluid, conventionally used in the production method of a compound) is obtained by using as a medium a carboxylic acid produced as a by-product and / or a raw carboxylic anhydride or a mixture thereof. The components of the liquid crystalline polyester can be acylated with carboxylic anhydride without the use of additional inorganic or organic solvents. That is, according to the production method of the present invention, it is not necessary to introduce the reaction solvent into the flow reactor together with the raw materials (components of liquid crystalline polyester and carboxylic anhydride).

In the acylation step of the present invention, a catalyst may or may not be used. It is preferable not to use a catalyst in that there is no need for post-treatment and disposal such as neutralization and detoxification of the solution after the reaction. In the case of using a catalyst, any of homogeneous catalysts and heterogeneous catalysts usually used in the synthesis of liquid crystalline polyesters (dialkyl tin oxide, diaryl tin oxide, titanium dioxide, alkoxy titanium silicates, titanium Alcoholates, alkali and alkaline earth metal salts of carboxylic acids, Lewis acid salts such as BF _3, etc.) can also be used.

  Examples of the reaction conditions in the acylation step include those usually applied in the acylation of the constituent components of the liquid crystalline polyester. For example, the temperature is 200 to 350 ° C., the pressure is 0.1 to 10 MPa, the reaction time is 1 to 90 seconds, More preferably, it may be 200 ° C. to 300 ° C., pressure 2-8 MPa, reaction time 1-60 seconds, most preferably 200 ° C.-250 ° C., pressure 5 MPa, time 1 second to 30 seconds. The reaction conditions can be appropriately set depending on the starting material used, the type of the desired reaction product, and the like.

  In the method for producing a liquid crystalline polyester according to the present invention, it is also possible to carry out polymerization by adding a stabilizer, a colorant, a filler and the like within a range not inhibiting or reducing the effect of the present invention.

  According to the production method of the present invention, the constituent components of the liquid crystalline polyester can be acylated with high conversion and selectivity. The acylated compound obtained by the production method of the present invention can be subjected to a known polymerization reaction (melt polymerization method, solution polymerization method, etc.) to obtain a liquid crystalline polyester.

  EXAMPLES Hereinafter, although an Example demonstrates this invention in more detail, this invention is not limited to these.

(Example 1: Investigation in catalyst-free system-I)
In a flow reactor (reaction tube used: stainless steel, Hastelloy or Inconel, outer diameter = 3.18 mm, inner diameter = 1.78 mm, length = 300 mm), reaction temperature 250 to 350 ° C., pressure 5 MPa, residence time 9 The mixed solution of 4-hydroxybenzoic acid and acetic anhydride was pumped at a rate of 0.5 ml / min under solvent-free and non-catalytic conditions under the condition of 0.0 second, and 4-hydroxybenzoic acid Was acylated. The ratio of 4-hydroxybenzoic acid to acetic anhydride is as shown in Table 1.

In addition, the meaning of the abbreviation in Table 1 is as follows.
HBA: 4-hydroxybenzoic acid Ac ₂ O: acetic anhydride

  Table 1 shows the results of acylation of 4-hydroxybenzoic acid (HBA). In the following, “yield” in the table is a value indicating the amount of product (molar amount) relative to the amount of raw material (molar amount) in 100 fractions, and “selectivity” is the whole product. This is a value indicating the amount of the target compound (molar amount of acyl body) with respect to (acyl body + compound other than raw material, molar amount) in 100 fractions. Further, the “mixing ratio” is the ratio of the hydroxyl group in the raw material to acetic anhydride.

  As shown in Table 1, according to the production method of the present invention, it is possible to acylate 4-hydroxybenzoic acid with high yield and selectivity even under solvent-free and non-catalytic conditions. It was.

(Example 2: Examination in non-catalytic system-II)
In the same manner as in Example 1, acylation of 4-hydroxybenzoic acid was performed. The results are shown in Table 2. Hereinafter, the “conversion rate” in the table indicates a value indicating the amount of the raw material consumed after the reaction with respect to the amount of the raw material used, expressed as a percentage.

  As shown in Table 2, according to the production method of the present invention, 4-hydroxybenzoic acid is acylated with high conversion, yield, and selectivity despite solvent-free and non-catalytic conditions. I was able to.

(Example 3: Investigation in non-catalytic system or catalytic system-I)
In the same manner as in Example 1, acylation of 6-hydroxy-2-naphthoic acid was performed. The results are shown in Table 3. In the “catalyst addition system”, sodium acetate was used as a catalyst. In the table, “HNA” indicates 6-hydroxy-2-naphthoic acid.

  As shown in Table 3, according to the production method of the present invention, 6-hydroxy-2-naphthoic acid was converted at a high conversion, yield and selectivity in the absence of a solvent regardless of the presence or absence of a catalyst. Acylation was possible.

(Example 4: Investigation in non-catalytic system-III)
In the same manner as in Example 1, acylation of 4,4′-dihydroxybiphenyl was performed. The results are shown in Table 4. In the table, “BP” represents 4,4′-dihydroxybiphenyl.

  As shown in Table 4, according to the production method of the present invention, 4,4′-dihydroxybiphenyl is acylated with a high yield and a high conversion rate even under solvent-free and catalyst-free conditions. I was able to.

(Example 5: Investigation in non-catalytic system or catalytic system-II)
In the same manner as in Example 1, acylation of 4-acetoxyaminophenol was performed. The results are shown in Table 5. In the “catalyst addition system”, sodium acetate was used as a catalyst. In the table, “APAP” represents 4-acetoxyaminophenol.

  As shown in Table 5, according to the production method of the present invention, 4-acetoxyaminophenol is acylated with a high conversion, yield and selectivity in the absence of a solvent regardless of the presence or absence of a catalyst. I was able to.

(Example 6: Investigation in non-catalytic system-IV)
In a flow reactor provided in a gas chromatography oven (reaction tube used: stainless steel, Hastelloy or Inconel, outer diameter = 3.18 mm, inner diameter = 1.78 mm, length = 300 mm or 1000 mm), reaction temperature 200 to A mixture of HBA, HNA, BP and APAP (HBA / HNA / BP / APAP = 1: 1: 1: 1, molar ratio under the conditions of 300 ° C., pressure 5 MPa, residence time 9.0 seconds or 30.0 seconds. ) And acetic anhydride mixed solution was pumped at a rate of 0.5 ml / min under solvent-free and catalyst-free conditions.

  As shown in Table 6, almost all monomers (HBA, HNA, BP, and APAP) were acylated.

Claims (2)

A liquid crystalline polyester comprising a component containing an aromatic carboxylic acid and / or a hydroxyl group-containing compound in a microreactor, and an acylation step in which carboxylic anhydride is introduced and an acylation reaction is performed under a solvent-free condition. Production method.   The production method according to claim 1, wherein the acylation step is performed under non-catalytic conditions.