JP6728788B2 - Method for producing liquid crystalline polyester resin - Google Patents

Description

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

Demand for liquid crystalline polyester resins is expanding, centering on small precision molded products for electrical and electronic applications, making use of their excellent heat resistance, fluidity, and electrical properties. Further, in recent years, attention has been paid to its thermal stability and high thermal dimensional accuracy, and studies have been made to use it as a supporting base material for heat-generating components such as a supporting base material for liquid crystal displays of OA devices and mobile phones, and structural components for lamps.

As a method of producing a liquid crystalline polyester resin, a method of performing a deacetic acid polycondensation reaction using two or more reaction tanks is known.

In the production of a liquid crystalline polyester resin, a predetermined amount of a monomer mixture and acetic anhydride are charged into a reaction tank, heated under a nitrogen gas atmosphere with stirring, and an acetylation reaction for acetylating a hydroxyl group under reflux, and then a predetermined amount. There are an oligomerization reaction in which acetic acid is distilled out to a specified amount while raising the temperature, and a polycondensation reaction in which the acetic acid distillation is completed by reducing the pressure and the reaction is advanced to a specified viscosity. Normally, an acetylation reaction tank and a polycondensation reaction tank are used with an emphasis on production efficiency. After the acetylation reaction is performed in the acetylation reaction tank and the specified acetic acid distillation rate is reached, the reaction liquid is changed to a polycondensation reaction tank. Generally, the method of transferring to

Among them, it has been studied to improve the quality and heat resistance of the polymer by carrying out the acetylation reaction in the acetylation reaction tank under specific conditions and then transferring the liquid to the polycondensation reaction tank (Patent Documents 1 and 2). ).

In addition, after the polycondensation reaction is completed, a filter is placed in at least one of the transfer pipes that connect the reaction cans (Patent Document 3), or the following raw materials are charged under specific conditions (Patent Document 4). It has been studied to obtain a liquid crystalline polyester resin in a small amount.

Further, it has been investigated to obtain a liquid crystalline polyester resin having a small amount of foreign matter by carrying out a polycondensation reaction under specific conditions (Patent Documents 5, 6 and 7).

On the other hand, when transferring the liquid from the acetylation reaction tank to the polycondensation reaction tank, by heating the liquid temperature of the polycondensation reaction tank to a specific condition, the occupancy time of the acetylation reaction tank can be shortened. It has been studied to reduce the capacity of the polycondensation reaction tank (Patent Document 8).

International Publication No. 2012/090747 (Claims) Japanese Patent Laid-Open No. 6-192404 (Claims) JP 2001-278988 A (claims) Japanese Patent Laid-Open No. 5-255495 (claims) JP, 2006-307007, A (claim) International Publication No. 2003/062299 (Claims) JP, 2006-299028, A (claim) Japanese Patent Laid-Open No. 2000-191762 (Claims)

However, in the methods of Patent Documents 1 and 2, the liquid level of the reaction liquid rises in the polycondensation reaction tank depending on the waiting conditions of the polycondensation reaction tank before liquid transfer. In the case of producing a polycondensation reaction, the polycondensation reaction tank occupies a longer time due to a delay in the polycondensation reaction time, or the washing cycle is accelerated due to blockage of the distilling line or clogging of the die. Further improvement is required because it causes deterioration of productivity (continuous batch productivity) and deterioration of quality.

Further, the methods of Patent Documents 3 and 4 are insufficient for suppressing the foreign matter generated in the gas phase portion of the polycondensation reaction tank, and further improvement has been demanded.

Further, in the methods of Patent Documents 5, 6 and 7, the acetic acid distillation rate at the time of transferring the liquid from the acetylation reaction tank to the polycondensation reaction tank and the specific temperature conditions of the polycondensation reaction tank are not described. , I can not expect a sufficient effect.

On the other hand, in the method of Patent Document 8, since a large amount of low-boiling components such as acetic acid are distilled out during liquid transfer, it is necessary to control the liquid transfer rate so as to suppress the liquid transfer, and the operation becomes complicated. The equipment cost is deteriorated because the container and the demultiplexer are large and have a complicated structure.

INDUSTRIAL APPLICABILITY The present invention is excellent in productivity and improves continuous batch productivity and polymer quality in a process of producing a liquid crystalline polyester resin by performing deacetic acid polycondensation reaction using an acetylation reaction tank and a polycondensation reaction tank. Provided is a method for producing a liquid crystalline polyester resin.

In the step of transferring the reaction liquid from the acetylation reaction tank to the polycondensation reaction tank in the step of producing a liquid crystalline polyester resin, the present inventors set the internal temperature of the polycondensation reaction tank to the reaction in the acetylation reaction tank. It has been found that by transferring the reaction solution after setting the reaction temperature within a specific range with respect to the temperature of the solution, the productivity is excellent, and the continuous batch productivity and the polymer quality can be improved.

That is, the present invention is a method for producing a liquid crystalline polyester resin containing a structural unit produced from hydroquinone using a production apparatus having at least an acetylation reaction tank and a polycondensation reaction tank, In the step of transferring the reaction liquid to the polycondensation reaction tank, the internal temperature of the polycondensation reaction tank is 250 to 264° C., and the temperature of the reaction liquid in the acetylation reaction tank is -30 to -3. This is a method for producing a liquid crystalline polyester resin in which liquid transfer is started within the range of °C.

The method for producing a liquid crystalline polyester resin of the present invention has excellent productivity and can improve continuous batch productivity and polymer quality.

FIG. 1 is a schematic view illustrating a facility for producing a liquid crystalline polyester resin. FIG. 2 is a schematic view illustrating a polycondensation reaction tank according to the present invention.

[Liquid crystal polyester resin]
The liquid crystalline polyester resin is a resin that forms an anisotropic molten phase, and examples thereof include liquid crystalline polyester resins having an ester bond such as liquid crystalline polyester and liquid crystalline polyesteramide.

Specific examples of the liquid crystalline polyester resin include a structural unit generated from p-hydroxybenzoic acid, a structural unit generated from 4,4′-dihydroxybiphenyl, a structural unit generated from hydroquinone, and a structural unit generated from terephthalic acid and/or isophthalic acid. , A structural unit formed from p-hydroxybenzoic acid, a structural unit formed from ethylene glycol, a structural unit formed from 4,4′-dihydroxybiphenyl, a structural unit formed from hydroquinone, and terephthalate A liquid crystalline polyester resin comprising a structural unit produced from an acid and/or isophthalic acid, a structural unit produced from p-hydroxybenzoic acid, a structural unit produced from ethylene glycol, a structural unit produced from 4,4′-dihydroxybiphenyl, and A liquid crystalline polyester resin comprising a structural unit produced from terephthalic acid and/or isophthalic acid, a structural unit produced from p-hydroxybenzoic acid, a structural unit produced from hydroquinone, a structural unit produced from 4,4′-dihydroxybiphenyl, A liquid crystalline polyester resin composed of a structural unit formed from 2,6-naphthalenedicarboxylic acid and a structural unit formed from terephthalic acid can be used. Among these, a preferable combination is a liquid crystalline polyester resin comprising a structural unit formed from p-hydroxybenzoic acid, hydroquinone, 4,4'-dihydroxybiphenyl and terephthalic acid and/or isophthalic acid.

As a monomer used in addition to hydroquinone, p-hydroxybenzoic acid, 4,4′-dihydroxybiphenyl, terephthalic acid and isophthalic acid, examples of aromatic hydroxycarboxylic acid include 6-hydroxy-2-naphthoic acid, and aromatic Examples of the dicarboxylic acid include 2,6-naphthalenedicarboxylic acid, 4,4′-diphenyldicarboxylic acid, 1,2-bis(phenoxy)ethane-4,4′-dicarboxylic acid, 1,2-bis(2-chloro). Examples thereof include phenoxy)ethane-4,4′-dicarboxylic acid and 4,4′-diphenyletherdicarboxylic acid. Examples of the aromatic diol include resorcinol, t-butylhydroquinone, phenylhydroquinone, chlorohydroquinone, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 3,4′-dihydroxybiphenyl, 2,2-bis(4-). Hydroxyphenyl)propane, 4,4′-dihydroxydiphenyl ether and the like can be mentioned. Examples of the monomer having an amino group include p-aminobenzoic acid and p-aminophenol.

Preferable examples of the liquid crystalline polyester resin forming the anisotropic molten phase include a liquid crystalline polyester resin composed of the structural units (I), (II), (III), (IV) and (V) below. ..

The structural unit (I) is a structural unit formed from p-hydroxybenzoic acid, the structural unit (II) is a structural unit formed from 4,4′-dihydroxybiphenyl, and the structural unit (III) is a structure formed from hydroquinone. The structural unit (IV) represents a structural unit produced from terephthalic acid, and the structural unit (V) represents a structural unit produced from isophthalic acid.

Hereinafter, this liquid crystalline polyester resin will be described as an example.

The copolymerization amount of the structural units (I), (II), (III), (IV) and (V) in the liquid crystal polyester resin composition is arbitrary. However, the following copolymerization amounts are preferable in order to exhibit the characteristics of the liquid crystalline polyester resin. The structural unit (I) is preferably 65 to 80 mol% based on the total of the structural units (I), (II) and (III). It is more preferably 68 to 78 mol %. The structural unit (II) is preferably 55 to 85 mol% with respect to the total of the structural units (II) and (III). It is more preferably 55 to 78 mol %, and most preferably 58 to 73 mol %. The structural unit (IV) is preferably 50 to 95 mol% based on the total of the structural units (IV) and (V). It is more preferably 55 to 90 mol %, and most preferably 60 to 85 mol %.

The sum of structural units (II) and (III) and the sum of (IV) and (V) are substantially equimolar. The term "substantially equimolar" as used herein means that the structural units constituting the polymer main chain excluding the terminals are equimolar. Therefore, even when the structural units that form the ends are included, the embodiments are not necessarily equimolar, and can satisfy the requirement of “substantially equimolar”.

In particular, when the above structural unit (III) formed from hydroquinone is contained, it takes time to obtain a homogeneous reaction solution with hydroquinone, and composition deviation easily occurs due to foaming or sublimation of hydroquinone. Can be particularly effective.

The liquid crystalline polyester resin preferably used is an aromatic dicarboxylic acid such as 3,3′-diphenyldicarboxylic acid or 2,2′-diphenyldicarboxylic acid in addition to the components constituting the structural units (I) to (V). , Adipic acid, azelaic acid, sebacic acid, dodecanedioic acid and other aliphatic dicarboxylic acids, hexahydroterephthalic acid and other alicyclic dicarboxylic acids, chlorohydroquinone, 3,4'-dihydroxybiphenyl, 4,4'-dihydroxydiphenyl Aromatic diols such as sulfone, 4,4′-dihydroxydiphenyl sulfide, 4,4′-dihydroxybenzophenone and 3,4′-dihydroxybiphenyl, propylene glycol, 1,4-butanediol, 1,6-hexanediol, neo Aliphatic and alicyclic diols such as pentyl glycol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol and m-hydroxybenzoic acid, polyethylene terephthalate, etc. are further added to the extent that liquid crystallinity and characteristics are not impaired. It can also be copolymerized.

For example, in the production of the above liquid crystalline polyester resin, the following production method is preferably cited. The following production method is described by taking as an example the synthesis of a liquid crystalline polyester resin composed of p-hydroxybenzoic acid, 4,4′-dihydroxybiphenyl, hydroquinone, terephthalic acid and isophthalic acid. It is not limited to these, and each can be replaced by polyethylene terephthalate, other hydroxycarboxylic acid, aromatic diol or aromatic dicarboxylic acid, and can be produced according to the following method.

In the embodiment of the present invention, the content of each structural unit in the liquid crystalline polyester resin can be calculated by the following process. That is, the liquid crystalline polyester is weighed in an NMR (nuclear magnetic resonance) test tube, dissolved in a solvent in which the liquid crystalline polyester is soluble (for example, a pentafluorophenol/heavy tetrachloroethane-d ₂ mixed solvent), and ¹ H- Perform NMR spectrum measurement. The content of each structural unit can be calculated from the peak area ratio derived from each structural unit.

[Method for producing liquid crystalline polyester resin]
Hereinafter, the method for producing the liquid crystalline polyester resin of the present invention will be described in detail.

In the production of the liquid crystalline polyester resin of the present invention, first, a predetermined amount of a monomer mixture and acetic anhydride are charged into an acetylation reaction tank, heated under a nitrogen gas atmosphere with stirring, and the hydroxyl groups are acetylated under reflux. Next, in the oligomerization reaction, the temperature is raised to a predetermined temperature while the acetic acid is distilled by switching to a distilling tube, and the acetic acid is distilled to a specified amount. Next, the reaction solution is transferred to a polycondensation reaction tank, followed by an oligomerization reaction, and a deacetic acid polycondensation reaction is performed while decompressing the polycondensation reaction tank. When the specified stirring torque is reached, deacetic acid polycondensation is performed. The reaction is terminated. When the deacetic acid polycondensation reaction is completed, stop the stirring, pressurize the polycondensation reaction tank with an inert gas such as nitrogen, form a strand from the bottom of the polycondensation reaction tank through the mouthpiece, and pellet it with a cutting device. Turn into.

The production of the liquid crystalline polyester resin of the present invention is preferably carried out by a batch type continuous polymerization method. As described above, the batch continuous polymerization method is to charge a batch of a predetermined amount of a monomer mixture and acetic anhydride into an acetylation reaction tank and, when the predetermined reaction is completed, to a polycondensation reaction tank. When the liquid is transferred and the predetermined reaction is completed, the polymer is discharged while pelletizing, and the second batch is also charged with a predetermined amount of the monomer mixture and acetic anhydride for one batch in the acetylation reaction tank in the same manner as above. , To carry out a predetermined reaction. In addition, a method of transferring the reaction solution of the acetylation reaction tank to the polycondensation reaction tank in a plurality of times, or a predetermined amount of the monomer mixture in the next batch while leaving a certain amount of the reaction solution in the acetylation reaction tank, A method of charging acetic anhydride is also included in the batch type continuous polymerization method.

The apparatus for producing a liquid crystalline polyester resin used in the present invention has at least two tanks, an acetylation reaction tank and a polycondensation reaction tank. Then, the acetylation reaction and the oligomerization reaction are performed in the first acetylation reaction tank, and the oligomerization reaction and the deacetic acid polycondensation reaction are performed in the second polycondensation reaction tank. As the acetylation reaction tank, for example, a tank equipped with a raw material inlet, a stirring blade, a rectification column, a distilling pipe, a reflux pipe, a condenser, a distilling acetic acid container, and a heating body can be used. As the polycondensation reaction tank, for example, a stirring blade, a distilling pipe, a condenser, a distilling acetic acid container, a heating body, a decompression device, and a tank having a discharge port at the bottom can be used. Further, it has a transfer line for transferring the reaction liquid from the acetylation reaction tank to the polycondensation reaction tank.

[Acetylation reaction and oligomerization reaction in acetylation reaction tank]
In the acetylation reaction and the oligomerization reaction in the acetylation reaction tank, the amount of acetic anhydride used is preferably 1.00 to 1.20 molar equivalents of the total of the phenolic hydroxyl groups in the liquid crystalline polyester resin raw material used. More preferably, it is 1.03 to 1.16 molar equivalents.

In the acetylation reaction, it is preferable to carry out the reaction while refluxing the reaction solution at a temperature of 125° C. or higher and 150° C. or lower until the residual amount of the monoacetylated product of the aromatic diol falls within a specific range. As a device for the acetylation reaction, for example, a reaction device equipped with a raw material inlet, a stirring blade, a rectification column, a distilling pipe, a reflux pipe, a condenser, a distilling acetic acid container, and a heating body can be used. The reaction time for acetylation is approximately 1 to 5 hours, but the time until the residual amount of the monoacetylated product of the aromatic diol falls within a specific range depends on the liquid crystalline polyester resin raw material used and the reaction temperature. Is also different. The time is preferably 1.0 to 2.5 hours, and the higher the reaction temperature is, the shorter the reaction proceeds, and the larger the molar ratio of acetic anhydride to the phenolic hydroxyl group terminal is, the shorter the time is.

Next, in the oligomerization reaction, when raising the temperature to a predetermined temperature while distilling acetic acid, it is preferable to perform the column top temperature of the rectification column in the range of 115°C to 150°C. More preferably, it is in the range of 130°C to 145°C. If the column top temperature is too low, a large amount of unreacted acetic anhydride remains in the system, which may cause coloration of the polymer and increase the amount of gas during heat retention. Moreover, by setting the column top temperature to 150° C. or lower, it is possible to prevent the monomers from distilling out of the system, resulting in composition deviation and reduction in the polymerization rate. In this case, the acetic acid to be distilled contains excess acetic anhydride and monomers, but the mass% of the monomers excluding acetic anhydride in acetic acid is preferably 1% by mass or less, and 0.5% by mass or less. Is more preferable.

Furthermore, in order to obtain a homogeneous liquid crystalline polyester resin, the relationship of the acetic acid distillation rate during the oligomerization reaction in the acetylation reaction tank is important, and the acetic acid distillation rate represented by the following formula (1) is It is preferable to continue the oligomerization reaction until it becomes 2.5%/10 minutes or less, and to transfer it to the polycondensation reaction tank at a temperature of the reaction solution in the acetylation reaction tank of 260° C. to 275° C., more preferably. Has an acetic acid distillation rate of 2.0%/10 minutes or less. By transferring the solution at an acetic acid distillation rate of 2.5%/10 minutes or less, the progress of the local polycondensation reaction can be suppressed during the transfer, and the scattering of low molecular weight monomers can be suppressed, resulting in a composition shift. It is preferable because a good liquid crystalline polyester resin having a small amount can be obtained. The smaller the acetic acid distillation rate, the more preferable, and most preferably, the acetic acid distillation rate is 0.1%/10 minutes or more and 1.8%/10 minutes or less. On the other hand, when it exceeds 2.5%/10 minutes, the amount of acetic acid to be distilled per unit time is large, so that the liquid level in the polycondensation reaction tank is likely to rise, or the acetic acid to be distilled out together with the monomers And oligomers are also scattered, which tends to cause compositional deviation.
Formula (1): Acetic acid distillation rate (%/10 minutes)=acetic acid liquid amount distilled in 10 minutes (g)/[[moles of acetic anhydride charged-moles of hydroxyl groups in raw material monomer]×acetic anhydride molecular weight + Mol number of hydroxyl group in raw material monomer x 2 x acetic acid molecular weight + mol number of acetyl group in raw material monomer x acetic acid molecular weight] (g) x 100 (%).
The amount of acetic acid distilled in 10 minutes here is the amount of acetic acid that has been distilled in addition to excess acetic anhydride and monomers, and is stored in the distilling acetic acid container of the acetylation reaction tank. The amount of acetic acid discharged is constantly measured, and it refers to the amount of acetic acid distilled in 10 minutes before the end point of the reaction in the acetylation reaction tank. The acetic acid distillation rate obtained by the above formula (1) The final acetic acid distillation rate in the acetylation reaction tank.

In addition, when the acetic acid distillation rate represented by the following formula (2) is set to 85% or more and then transferred to the polycondensation reaction tank, the reaction of the remaining dicarboxylic acid is also promoted, and a homogeneous reaction solution is obtained. When a filter having an opening of 0.5 mm or less is provided in the liquid line, it can be preferably used as a condition for obtaining a polymer of good quality with less foreign matter.
Formula (2): Acetic acid distillation rate (%)=Distilled acetic acid solution amount (g)/[[mol number of acetic anhydride charged-mol number of hydroxyl group in raw material monomer]×acetic anhydride molecular weight+hydroxy group in raw material monomer X 2 x acetic acid molecular weight + mole number of acetyl group in raw material monomer x acetic acid molecular weight] (g) x 100 (%).
The amount of distilled acetic acid as used herein means the amount of distillated acetic acid as well as excess acetic anhydride and monomers.

In the present application, the start of the oligomerization reaction in the acetylation reaction tank means the time when the acetylation reaction ends and the distillation of acetic acid starts, and the end point in the acetylation reaction tank means the distillation pipe. The valve is closed and the distillation of acetic acid is completed.

[Transfer process of reaction solution from acetylation reaction tank to polycondensation reaction tank]
The transfer of the reaction liquid from the acetylation reaction tank to the polycondensation reaction tank is performed via a transfer line connecting the respective reaction tanks. The liquid transfer line may be provided with a filter for collecting foreign matters of the reaction liquid passing through it, and may have a heating body for heating the reaction liquid. The position and type of the heating element are not particularly limited, and may be attached to the inner wall surface of the liquid transfer line, embedded inside the wall, or attached to the outer wall surface of the liquid transfer line to indirectly heat the inner wall surface. .. Examples of the type of heating body include a method of heating by covering with a coil, a jacket, or a belt-shaped heating body. Among these, the method of attaching a jacket to the outer wall surface is preferable in that the heating range can be heated at a uniform temperature. As a heating method of the heating element, a method of circulating a vapor or a liquid heating medium in a coil or a jacket, a method of heating the heating element with a heating wire, and the like are used. A method of circulating a vapor or a liquid heat medium is preferable, and a method of circulating a liquid heat medium in a jacket with a pump is preferable, and this method can stably control the temperature. The temperature of the heating medium is the temperature of the heating medium measured by a thermometer attached to the inlet of the coil or the jacket when the heating medium circulation line is used as the heating body as the jacket. It is preferable that the temperature of the heating element of the liquid transfer line at the time of liquid transfer is within the range of −20 to +10° C. with respect to the temperature of the reaction liquid in the acetylation reaction tank before the liquid transfer. More preferably, it is in the range of -15 to +8°C. When the temperature is +10° C. or less, it is possible to prevent the progress of the polymerization during the liquid transfer and the rise of the liquid level of the reaction liquid due to the by-product acetic acid. On the other hand, when the temperature is −20° C. or higher, the temperature of the reaction liquid does not drop to a temperature close to the melting point or the freezing point of the reaction liquid when the liquid is transferred.

As the device of the polycondensation reaction tank, for example, a stirring blade, a distilling pipe, a condenser, a distilling acetic acid container, a heating body, a decompression device, and a reaction device having a discharge port at the bottom can be used. The position and type of the heating element are not particularly limited, and may be attached to the inner wall surface of the polycondensation reaction tank, embedded in the wall, or attached to the outer wall surface to indirectly heat the inner wall surface. Examples of the type of heating body include a method of heating by covering with a coil, a jacket, or a belt-shaped heating body. Among these, the method of attaching a jacket to the outer wall surface is preferable in that the heating range can be heated at a uniform temperature. As a heating method of the heating element, a method of circulating a vapor or a liquid heating medium in the coil or the jacket, a method of heating the heating element with a heating wire, and the like are used. A method of circulating a vapor or a liquid heat medium is preferable, and a method of circulating a liquid heat medium in a jacket with a pump is preferable, and this method can stably control the temperature. The heating body of the polycondensation reaction tank here refers to a heating body arranged on the surface in contact with the reaction liquid, and the heating body may be divided into a plurality in the height direction. When the heating element is divided into a plurality of pieces, it indicates the heating element located closest to the bottom of the reaction tank among the heating elements arranged on the surface in contact with the reaction solution. The temperature of the heating medium is the temperature of the heating medium measured by a thermometer attached to the inlet of the coil or jacket when the heating medium circulation line is used as the heating body as a coil or a jacket.

The method of transferring the reaction liquid from the acetylation reaction tank to the polycondensation reaction tank is not particularly limited, but it is a method of allowing the acetylation reaction tank and the polycondensation reaction tank to fall naturally due to the difference in height or a closed system of the acetylation reaction tank. In addition, there is a method of transferring by pressurizing with an inert gas such as nitrogen, but in terms of shortening the transfer time and not deteriorating the quality of the liquid crystalline polyester resin, pressurizing with an inert gas etc. to transfer the liquid. The method of doing is preferable. In addition, when a filter is installed in the transfer line, pressure loss occurs when foreign matter is collected in the filter eyes, and it takes a long time to transfer liquid by spontaneous fall. A method in which the reaction tank is pressurized with an inert gas such as nitrogen and pressure-fed is preferable.

As a standby method of the polycondensation reaction tank before carrying out the liquid transfer, the internal temperature and the temperature of the heating body are set to a predetermined temperature so that the volume transferred from the acetylation reaction tank can be released to the outside of the system. It is preferable to use a method of releasing it to the outside of the system via a distillation pipe or a condenser. According to this method, acetic acid distilled during liquid transfer can be collected in a distilling acetic acid container in high yield. While the reaction solution is being transferred, the stirring blade of the polycondensation reaction tank may be operating or stopped, but the stirring shaft has a thick fixed rod extending from the central axis toward the wall surface. In this case, there is a possibility that the reaction liquid from the acetylation reaction tank adheres to or scatters on the stirring blade, so it is preferable to stop the stirring blade and transfer the liquid.

In the production method of the present invention, when the liquid is transferred from the acetylation reaction tank to the polycondensation reaction tank, the internal temperature of the polycondensation reaction tank is set to −30 to −3° C. with respect to the temperature of the reaction liquid in the acetylation reaction tank. It is necessary to start the liquid transfer within the range of. More preferably, it is in the range of -20°C to -4°C. If the temperature is higher than -3°C, the polymerization progresses during the transfer of liquid to raise the liquid level of the reaction liquid due to by-product acetic acid, and the monomers having a low melting point and the oligomers having a low molecular weight are easily scattered out of the system. In this way, when the liquid level of the reaction liquid rises, the reaction liquid adheres to the gas phase portion and undergoes a thermal history to raise the melting point, and the amount of adhesion increases as the number of continuous batches increases. Furthermore, when a certain number of batches are reached, the deposits fall and become high melting point foreign substances mixed in the pellets, or the die part is clogged with the foreign substances and the polymer cannot be discharged. Further, when the liquid level rises, monomers having a low melting point and oligomers having a low molecular weight are scattered out of the system, which may cause composition deviation, decrease in yield, or decrease in polymerization rate. .. Further, the heat history of the polymer is lowered and the color tone of the polymer is deteriorated due to the long thermal history. On the other hand, if the temperature is lower than −30° C., the temperature of the reaction solution may decrease to a temperature close to the melting point or the freezing point of the reaction solution when the liquid is transferred, which may increase the viscosity of the reaction solution or partially It solidifies or the temperature rise after liquid transfer takes a long time. The temperature of the reaction solution in the acetylation reaction tank here refers to the temperature measured by the temperature element attached to the inner wall of the reaction solution portion of the acetylation reaction tank, and when the temperature element is not in contact with the reaction solution, Refers to the internal temperature of the acetylation reaction tank. Further, the internal temperature of the polycondensation reaction tank refers to the temperature measured by a temperature element attached to the position of the inner wall which is in contact with the reaction solution during the polycondensation reaction. It may or may not be dipped in the residual polymer, but it is preferable that it is not dipped in the residual polymer from the viewpoint that the liquid temperature can be accurately measured. After starting the liquid transfer at the internal temperature of the polycondensation reaction tank shown above, the internal temperature of the polycondensation reaction tank during liquid transfer changes to a temperature close to the reaction liquid with the transfer of the reaction liquid, The temperature may be higher than the upper limit (temperature of reaction solution −3° C.) during transfer.

It is preferable that the temperature of the heating body in the polycondensation reaction tank at the time of transferring the liquid is in the range of −20 to −1° C. with respect to the temperature of the reaction liquid in the acetylation reaction tank before starting the liquid transfer. More preferably, it is in the range of -15°C to -2°C. When the temperature is -1°C or less, the polymerization partially progresses in the vicinity of the heating body, and the rise of the liquid level can be suppressed. On the other hand, when the temperature is −20° C. or higher, the temperature of the reaction solution is lowered to a temperature close to the melting point or the freezing point of the reaction solution when the liquid is transferred, and the viscosity of the reaction solution is increased or partially solidified, It does not take a long time to raise the temperature after the transfer.

In the step of transferring the reaction liquid from the acetylation reaction tank to the polycondensation reaction tank, the acetic acid distillation rate in the polycondensation reaction tank during transfer represented by the following formula (3) is 5.0% or less. It is preferably in the range of 0.1-4.5%. If it is more than 5.0%, the liquid level is likely to rise in the polycondensation reaction tank, and the monomer and the oligomer are scattered together with the acetic acid to be distilled off, and the composition is liable to be displaced.
Formula (3): Distillation rate of acetic acid during transfer (%) = Amount of acetic acid distilled during transfer (g)/[[mol number of acetic anhydride charged-mol number of hydroxyl group in raw material monomer] x anhydrous Acetic acid molecular weight+moles of hydroxyl group in raw material monomer×2×acetic acid molecular weight+moles of acetyl group in raw material monomer×acetic acid molecular weight] (g)×100(%).

The “amount of acetic acid solution distilled during transfer” was accumulated in the distilling acetic acid container connected to the polycondensation reaction tank by a distillation line between the start of transfer of the reaction solution and the end of transfer. The amount of acetic acid is the amount of liquid containing excess acetic anhydride and monomers in addition to distilled acetic acid.

The time required for transferring the reaction solution is 1.0 to 15.0 times the transfer time (time required for transfer) with respect to the polymerization time (time required for polycondensation reaction) represented by the following formula (4). %, and more preferably 1.0 to 12.5%. When the liquid transfer time relative to the polymerization time is 15.0% or less, the time during which the reaction solution is sealed in the acetylation reaction tank does not become too long, and the polymerization partially proceeds in the vicinity of the heating body, resulting in There is no possibility that the surface rises easily and that the temperature of the reaction solution gradually decreases and the temperature rise after transfer does not take a long time. On the other hand, when it is 1.0% or more, the flow rate of the reaction solution increases, so that the reaction solution jumps up and the reaction solution adheres to the gas phase part, or monomers and oligomers scatter along with acetic acid during transfer. Can be suppressed.
Formula (4): liquid transfer time/polymerization time ratio (%)=time required for liquid transfer (minutes)/total time required for polycondensation reaction (minutes)×100 (%).

In the case of the method of transferring by pressurizing with an inert gas such as nitrogen, the transfer time here is from the time when the acetylation reaction tank is closed system, and the transfer of the reaction solution is completed and It refers to the time until the temperature of the heating element in the condensation reaction tank is raised. Also, in the case of a method in which the reaction mixture is allowed to fall naturally due to the difference in height between the acetylation reaction tank and the polycondensation reaction tank, the transfer is completed and the temperature of the heating element in the polycondensation reaction tank is raised from the time when the transfer of the reaction solution is started. It is the time until the start of. The polymerization time is the time from the time when the transfer of the reaction solution is completed and the temperature of the heating element in the polycondensation reaction tank is started to the time when the specified stirring torque is reached and the stirring blades are stopped.

[Oligomerization reaction and deacetic acid polycondensation reaction in polycondensation reaction tank]
When the liquid transfer from the acetylation reaction tank is completed, the stirring blade is stopped and the liquid transfer is started, the operation is started, and the heating body is heated at a prescribed temperature rising rate to carry out the oligomerization reaction. ..

As a stirring blade of the polycondensation reaction tank, it is preferable to use a reaction vessel provided with a helical ribbon blade, and more preferably, a helical ribbon blade having a ribbon blade attached to a frame having no central axis (hereinafter referred to as central axis With and without a helical ribbon). The clearance from the polycondensation reaction tank is preferably 50 mm or less, more preferably 20 mm or less.

In the polycondensation reaction, the rotational direction of the helical ribbon blade is more preferably the scraping direction in order to prevent the reaction liquid from rising due to foaming or sublimation of the reaction liquid. The scraping direction as used herein means that the reaction liquid near the wall surface of the can is pushed down toward the bottom of the can by the rotation direction of the ribbon blade. On the contrary, the scraping direction means that the reaction liquid near the wall surface of the can is pushed upward by the rotating direction of the ribbon blade.

When the temperature and time of the target reaction solution are reached, the melt polymerization method is preferable in which the distillation line is switched to the depressurization device side and the deacetic acid polycondensation reaction is completed while depressurizing. The melt polymerization method is an advantageous method for producing a uniform polymer, and is preferable because a polymer with a smaller gas generation amount can be obtained.

The final polymerization temperature is preferably about the melting point+20° C., and is preferably 370° C. or lower.

The degree of reduced pressure during the polymerization is usually 13.3 Pa (0.1 torr) to 2666 Pa (20 torr), preferably 1333 Pa (10 torr or less), and more preferably 667 Pa (5 torr) or less. As a preferable polymerization rate, it is preferable that the time from when the degree of reduced pressure becomes 1333 Pa (10 torr) to when the specified torque is detected and the polycondensation reaction is completed is 0.3 to 1.0 hour. When it is 1.0 hour or less, it is possible to prevent the polymer from being colored due to heat history and from being deteriorated in heat resistance. On the other hand, by setting the time to 0.3 hours or more, it is possible to degas acetic acid and remove excess monomer components, and reduce the amount of gas in the pellets and the sublimate.

After the deacetic acid polycondensation reaction is completed, the polymer obtained is taken out from the polycondensation reaction tank by pressurizing the inside of the polycondensation reaction tank at a temperature at which the polymer melts to, for example, about 0.02 to 0.5 MPa to carry out polycondensation. A resin pellet can be obtained by discharging a strand from a discharge port provided in the lower part of the reaction tank, cooling the strand in cooling water, and cutting into a pellet. The melt polymerization method is an advantageous method for producing a uniform polymer, and is preferable because an excellent polymer with a smaller gas generation amount can be obtained.

After discharging the molten polymer, the internal temperature of the polycondensation reaction tank is controlled to cool the polymer to a temperature of crystallization temperature (Tc) −5° C. or lower, and then the reaction liquid is transferred. It is preferable to raise the temperature to the internal temperature of the polycondensation reaction tank and the temperature of the heating body before liquid transfer. When the polymer is cooled to a temperature lowering crystallization temperature (Tc) of -5°C or lower, it is preferable because the high melting point of the residual polymer in the polycondensation reaction tank is suppressed and the generation of foreign matter can be suppressed. The temperature-decreasing crystallization temperature (Tc) of the polymer is 20° C. higher than the endothermic peak temperature (Tm1) observed when measured with a differential scanning calorimeter (DSC) at a temperature rising condition from room temperature to 20° C./min. It is an exothermic peak temperature observed when the temperature (Tm1+20° C.) is held for 5 minutes and then the temperature is measured at a temperature lowering condition of 20° C./minute.

When producing the liquid crystalline polyester resin, the polycondensation reaction can be completed by a solid phase polymerization method. For example, the polymer or oligomer of the liquid crystalline polyester resin is pulverized with a pulverizer, and heated under a nitrogen stream or under reduced pressure in the range of melting point −5° C. to melting point −50° C. of the liquid crystalline polyester resin for 1 to 50 hours, and then desired. Examples of the method include polycondensation up to the degree of polymerization to complete the reaction. The solid-state polymerization method is an advantageous method for producing a polymer having a high degree of polymerization.

The melt viscosity of the liquid crystalline polyester resin is preferably 10 to 500 Pa·s. It is more preferably 12 to 200 Pa·s. The melt viscosity is a value measured by a Koka type flow tester under the condition of melting point (Tm)+10° C. and shear rate of 1000 (1/sec).

The melting point of the liquid crystalline polyester resin is not particularly limited, but it is preferable to combine the copolymerization components so as to be 280° C. or higher for use in high heat resistance applications.

Although the polycondensation reaction of the liquid crystalline polyester resin proceeds without a catalyst, metal compounds such as stannous acetate, tetrabutyl titanate, potassium acetate, sodium acetate, and magnesium antimony metal oxide can also be used.

In order to impart mechanical strength and other properties to the liquid crystalline polyester resin, a filler can be further added. The filler is not particularly limited, but fibrous, plate-like, powdery, granular, etc. fillers can be used. Specifically, for example, glass fibers, PAN-based or pitch-based carbon fibers, stainless fibers, metal fibers such as aluminum fibers and brass fibers, organic fibers such as aromatic polyamide fibers and liquid crystalline polyester fibers, gypsum fibers, ceramic fibers. , Asbestos fiber, zirconia fiber, alumina fiber, silica fiber, titanium oxide fiber, silicon carbide fiber, rock wool, basalt fiber, titanium oxide whiskers, potassium titanate whiskers, barium titanate whiskers, aluminum borate whiskers, silicon nitride whiskers, etc. Fibrous, whisker-like filler, mica, talc, kaolin, silica, glass beads, glass flakes, glass microballoons, clay, molybdenum disulfide, wollastonite, titanium oxide, zinc oxide, calcium polyphosphate and graphite And granular or plate-shaped fillers. The surface of the filler may be treated with a known coupling agent (for example, a silane coupling agent, a titanate coupling agent, etc.) or another surface treatment agent for use.

Among these fillers, glass fiber is particularly preferably used from the viewpoint of balance between availability and mechanical strength. The type of glass fiber is not particularly limited as long as it is generally used for reinforcing a resin, and for example, long fiber type or short fiber type chopped strands and milled fibers can be selected and used. Also, two or more of these may be used in combination. As the glass fiber, weakly alkaline one is excellent in mechanical strength and can be preferably used. Further, the glass fiber is preferably treated with a coating or sizing agent such as an epoxy type, urethane type or acrylic type, and an epoxy type is particularly preferable. Further, it is preferably treated with a silane-based or titanate-based coupling agent or other surface treatment agent, and an epoxysilane- or aminosilane-based coupling agent is particularly preferable.

The glass fibers may be coated or bundled with a thermoplastic resin such as an ethylene/vinyl acetate copolymer or a thermosetting resin such as an epoxy resin.

The compounding amount of the filler is usually 30 to 200 parts by mass, and preferably 40 to 150 parts by mass with respect to 100 parts by mass of the liquid crystalline polyester resin.

Further, the liquid crystalline polyester resin includes an antioxidant and a heat stabilizer (for example, hindered phenol, hydroquinone, phosphites and their substitution products), an ultraviolet absorber (for example, resorcinol, salicylate), a phosphite or Anti-coloring agents such as hypophosphite, lubricants and mold release agents (such as montanic acid and its metal salts, its esters, its half esters, stearyl alcohol, stearamide and polyethylene wax), colorants including dyes and pigments, conductive Usually used as agents or colorants such as carbon black, crystal nucleating agents, plasticizers, flame retardants (bromine flame retardants, phosphorus flame retardants, red phosphorus, silicone flame retardants, etc.), flame retardant aids, and antistatic agents. The additive and the polymer other than the thermoplastic resin can be blended to further impart predetermined characteristics.

The method of blending these additives is preferably melt kneading, and known methods can be used for melt kneading. For example, using a Banbury mixer, a rubber roll machine, a kneader, a single-screw or twin-screw extruder, etc., it is possible to melt-knead at a temperature of 180 to 350° C., more preferably 250 to 320° C. to obtain a liquid crystalline polyester resin composition. it can. In that case, 1) liquid crystal polyester resin, a batch kneading method with a filler which is an optional component, and other additives, 2) first, a liquid crystal polyester resin containing other additives in a high concentration in the liquid crystal polyester resin Method of preparing composition (master pellet) and then adding other thermoplastic resin, filler and other additives so as to have a specified concentration (master pellet method), 3) liquid crystalline polyester resin and other Any method such as a divided addition method in which a part of the additives is kneaded once and then the remaining filler and other additives are added may be used.

The liquid crystalline polyester resin and the liquid crystalline polyester resin composition containing it have excellent surface appearance (color tone) and mechanical properties, heat resistance, flame retardancy by ordinary molding methods such as injection molding, extrusion molding and press molding. Can be processed into a three-dimensional molded product, sheet, container, pipe, film and the like. Among them, it is suitable for electric/electronic parts obtained by injection molding.

The liquid crystalline polyester resin thus obtained and the liquid crystalline polyester resin composition containing the same are used, for example, in relay-related parts, coil-related parts, switches and motor-related parts, sensor-related parts, bearing-related parts, HDD-related parts. , LED related parts, connector related parts, sound absorbing/buffer material related parts, films, fibers, etc.

Hereinafter, the present invention will be specifically described with reference to Examples and Comparative Examples, but the present invention is not limited thereto.

Using the manufacturing equipment for the liquid crystalline polyester resin shown in FIGS. 1 and 2, the manufacturing steps of Examples 1 to 6 and Comparative Examples 1 to 3 were respectively performed up to 20 times (20 batches), and the following (1) to ( The evaluation shown in 7) was performed. In addition, when the test was finished in batches less than the maximum number of batches, the average value up to the finished batch was described.

(1) Final acetic acid distillation rate in the acetylation reaction tank (%/10 minutes)
During the reaction in the acetylation reaction tank 1, the acetic acid mass (g) in the distilling acetic acid container 7 was constantly measured, and the final acetic acid distillation rate in the acetylation reaction tank was calculated as the acetic acid distillation rate for 10 minutes as follows. Calculated from the formula.
Acetic acid distillation rate (%/10 minutes)=acetic acid distillate amount distilled in 10 minutes (g)/[[moles of acetic anhydride charged-moles of hydroxyl groups in raw material monomer]×acetic anhydride molecular weight+raw material monomer The number of moles of hydroxyl group in the product×2×the molecular weight of acetic acid+the number of moles of the acetyl group in the raw material monomer×the molecular weight of acetic acid] (g)×100(%).

(2) Acetic acid distillation rate (%) during transfer
The mass (g) of acetic acid in the distilling acetic acid container 17 of the polycondensation reaction tank 12 that was distilled from the start of liquid transfer to the end of liquid transfer was measured and calculated from the following formula. The acetic acid distillation rate was calculated for each test batch, and the average value of 20 batches was calculated.
Acetic acid distillation rate (%)=acetic acid solution amount distilled during transfer (g)/[[mol number of acetic anhydride charged-mol number of hydroxyl group in raw material monomer]×acetic anhydride molecular weight+of hydroxyl group in raw material monomer Number of moles x 2 x molecular weight of acetic acid + number of moles of acetyl group in raw material monomer x molecular weight of acetic acid] (g) x 100 (%).

(3) Number of batches in which clogging of the mouthpiece occurred The test batches were continuously performed, and the number of batches in which the mouthpiece of the discharge port began to become clogged was examined.

(4) Polycondensation reaction tank liquid surface height ratio (%)
Before the liquid transfer from the acetylation reaction tank 1, the SUS rod 21 is inserted from the upper flange of the polycondensation reaction tank 12 and, after the discharge is completed, from the position 22 where the reaction liquid is attached to the SUS rod 21. The adhering height 23 of the reaction solution was examined, and it was determined from the height 24 of the inner wall of the polycondensation reaction tank by the following formula (see FIG. 2).
Polycondensation reaction tank liquid surface height ratio (%)=reaction liquid adhesion height 23 (mm)/polycondensation reaction tank inner wall height 24 (mm)×100 (%)
After completion of the inspection, a SUS rod 21 having no adhering reaction liquid was inserted, the liquid level ratio of the polycondensation reaction tanks of all test batches was examined, and the average value of 20 batches was obtained.

(5) Product yield (%)
The product yield was calculated by the following formula for each test batch, and the average of 20 batches was calculated.
Product yield (%) = pellet mass (kg) / theoretical polymer mass (kg) x 100 (%)

(6) Melting point (℃)
The measurement was performed using a differential scanning calorimeter DSC-7 manufactured by Perkin Elmer. The endothermic peak temperature (Tm1) observed when the measurement was performed at a temperature rising condition from room temperature of 20° C./min was observed. Then, after being held at a temperature of Tm1+20° C. for 5 minutes, the temperature was once cooled to room temperature under a temperature lowering condition of 20° C./min, and an endothermic peak temperature (Tm2) observed when measured again under a temperature rising condition of 20° C./min. Was taken as the melting point. The melting point was determined for each test batch and the average of 20 batches was determined.

(7) Color tone (L value)
The color tone (L value) of the pellet obtained for each test batch was measured using an SM color computer device manufactured by Suga Test Instruments Co., Ltd. The color tone was measured for each test batch and the average of 20 batches was obtained.

(Example 1)
An acetylation reaction tank 1 having a volume of 5 L having a helical blade (stirring blade 2), a rectification column 3, a distillation line 4, a reflux line 5, a condenser 6, a distilling acetic acid container 7, and a raw material charging line 8 was prepared. .. As a heating element, the outer wall surface of the acetylation reaction tank 1 is covered with a jacket, and a heating medium and a circulation pump are used to circulate a heat medium (Therms 600 manufactured by Nippon Steel Chemical Co., Ltd.) in the jacket. Polymerization was carried out.

In the acetylation reaction tank 1, 1012 parts by mass of p-hydroxybenzoic acid (54 mol%), 409 parts by mass of 4,4′-dihydroxybiphenyl (16 mol%), 104 parts by mass of hydroquinone (7 mol%), 339 parts by mass of terephthalic acid. Parts (15 mol %), 182 parts by mass of isophthalic acid (8 mol %) and 1527 parts by mass of acetic anhydride (1.10 equivalents of the total phenolic hydroxyl groups) were charged from the raw material charging line 8. While stirring the charged raw materials under a nitrogen gas atmosphere, the temperature of the heating body was controlled so that the temperature of the reaction solution was maintained at 145° C., and the acetylation reaction was performed on the reflux line 5 side for 1.5 hours.

Next, the distillation line 4 was switched to the distillation acetic acid container 7 side, and the temperature of the heating element was controlled and raised over 180 minutes so that the temperature of the reaction liquid became 270°C. The final acetic acid distillation rate in the acetylation reactor was 1.0%/10 minutes.

Next, as a polycondensation reaction tank, as shown in FIG. 2, a liquid transfer line 9, a liquid transfer valve 11, a distilling line 14, a condenser 15, a decompression device 16, a distilling acetic acid container 17, a discharge valve 18, a discharge port 19. , Having a thermometer 25, the gap between the inner wall of the polycondensation reaction tank 12 and the helical ribbon blade (stirring blade 13) having no central axis is 5 mm, and the material of the inner wall is SUS316L and the volume of 5 L The condensation reaction tank 12 was used.

As the heating body 20 of the polycondensation reaction tank 12, a heating medium was circulated in the jacket in the same manner as in the acetylation reaction tank 1, and polymerization was carried out as follows while controlling the temperature.

As the heating body 10 of the liquid transfer line 9, a heating medium was circulated in the jacket in the same manner as in the acetylation reaction tank 1 to control the temperature.

The temperature of the heating element 20 in the polycondensation reaction tank 12 was controlled to 265°C, and the internal temperature was kept at 260°C. The temperature of the heating element 10 in the liquid transfer line 9 was controlled to 270° C., and the process waited. Next, the reaction liquid having a temperature of 270° C. in the acetylation reaction tank 1 is transferred through the transfer line 9 by opening the transfer valve 11, and the transfer line 9 is blown twice with nitrogen to transfer the liquid. The valve 11 was closed. The time required for the liquid transfer was 10 minutes, and the distillation rate of acetic acid during the liquid transfer was 0.5%. Next, in the polycondensation reaction tank 12, while stirring in a scraping direction under a nitrogen gas atmosphere, the temperature of the reaction solution was raised to 335° C. over 1.5 hours, and decompression was started by the decompression device 16, The pressure was reduced to 133 Pa (1 torr) over 1.5 hours. The polycondensation reaction was continued while further reducing the pressure, and when the specified stirring torque was reached, the deacetic acid polycondensation reaction was terminated. The polycondensation reaction time after reaching a vacuum degree of 1333 Pa (10 torr) was 19 minutes (average value of 20 batches). Next, the inside of the polycondensation reaction tank 2 was pressurized with nitrogen to 0.1 MPa, the discharge valve 18 was opened, and the polymer was discharged into a strand-like material via a die attached to a circular discharge port 19 having a diameter of 10 mm. , Pelletized with a cutter. After the discharge was completed, the SUS rod 21 was taken out from the upper flange of the polycondensation reaction tank 12, and the liquid level height ratio was calculated. After completion of the inspection, a SUS rod 21 free from the reaction liquid was inserted. Polymerization of 20 batches was repeated by the above method.

There was no problem with clogging of the die and no problem with product yield. There was no problem with the liquid level height ratio in the polycondensation reaction tank 12. There was no problem regarding the melting point and color tone (L value) of the obtained pellets.

(Example 2)
The temperature of the heating body 20 of the polycondensation reaction tank 12 before liquid transfer is controlled to 269° C., and the reaction liquid having a temperature of 270° C. in the acetylation reaction tank is controlled while the internal temperature of the polycondensation reaction tank is 264° C. It carried out like Example 1 except having transferred the liquid.

The acetic acid distillation rate during transfer was 1.1%.

The polycondensation reaction time after reaching the vacuum degree of 1333 Pa (10 torr) was 37 minutes (average value of 20 batches). Clogging of the die began to be seen in the 17th batch, but it was slight and the product yield was satisfactory. There was no problem with the liquid level height ratio in the polycondensation reaction tank 12. There was no problem regarding the melting point and color tone (L value) of the obtained pellets.

(Example 3)
The temperature of the heating body 20 of the polycondensation reaction tank 12 before liquid transfer is controlled to 255° C., and the reaction liquid having a temperature of 270° C. in the acetylation reaction tank is heated while the internal temperature of the polycondensation reaction tank is 250° C. It carried out like Example 1 except having transferred the liquid.

The acetic acid distillation rate during transfer was 0.3%.

The polycondensation reaction time after reaching a vacuum degree of 1333 Pa (10 torr) was 25 minutes (average value of 20 batches). There was no problem with clogging of the die and no problem with product yield. There was no problem with the liquid level height ratio in the polycondensation reaction tank 12. There was no problem regarding the melting point and color tone (L value) of the obtained pellets.

(Example 4)
The temperature of the reaction liquid in the acetylation reaction tank 1 was raised to 265° C. over 180 minutes, and the temperature of the heating element 10 in the liquid transfer line 9 was controlled to 265° C. Example 12 except that the temperature of the heating element 20 of No. 12 was controlled to 260° C., and the reaction liquid having a temperature of 265° C. in the acetylation reaction tank was transferred while the internal temperature of the polycondensation reaction tank was 255° C. The same procedure as 1 was performed.

The final acetic acid distillation rate in the acetylation reactor was 2.0%/10 minutes.

The acetic acid distillation rate during the transfer was 1.8%.

The polycondensation reaction time after reaching a vacuum degree of 1333 Pa (10 torr) was slightly delayed to 44 minutes (average value of 20 batches). Clogging of the base began to appear at the 16th batch, but continuous operation of 20 batches was possible. There was no problem with product yield. There was no problem with the liquid level height ratio in the polycondensation reaction tank 12. The melting point of the obtained pellets tended to be slightly lower, and the color tone (L value) tended to be slightly lowered.

(Example 5)
The same procedure as in Example 1 was performed except that the temperature of the heating element 10 in the liquid transfer line 9 was controlled at 280°C.

The acetic acid distillation rate during transfer was 1.0%.

The polycondensation reaction time after reaching the vacuum degree of 1333 Pa (10 torr) was 30 minutes (average value of 20 batches). Clogging of the base began to be seen in the 19th batch, but it was slight and continuous operation of 20 batches was possible. There was no problem with product yield. There was no problem with the liquid level height ratio in the polycondensation reaction tank 12. There was no problem regarding the melting point and color tone (L value) of the obtained pellets.

( Reference example 6)
The components charged into the acetylation reaction tank 1 were changed to the following, and the temperature of the reaction liquid in the acetylation reaction tank 1 was raised over 180 minutes to reach 265° C., and the polycondensation reaction tank before transfer was carried out. Example 12 except that the temperature of the heating element 20 of No. 12 was controlled to 260° C., and the reaction liquid having a temperature of 265° C. in the acetylation reaction tank was transferred while the internal temperature of the polycondensation reaction tank was 255° C. The same procedure as 1 was performed.
1354 parts by mass of p-hydroxybenzoic acid (73 mol%)
*4,4'-dihydroxybiphenyl 228 mass parts (9 mol%)
-Terephthalic acid 204 parts by mass (9 mol%)
-Polyethylene terephthalate 236 parts by mass (9 mol%)
-Sodium hypophosphite 0.36 parts by mass (0.02% by mass)
1382 parts by mass of acetic anhydride (1.11 equivalent of total phenolic hydroxyl groups)
The acetic acid distillation rate during transfer was 0.4%.

The polycondensation reaction time after reaching a vacuum degree of 1333 Pa (10 torr) was 24 minutes (average value of 20 batches). There was no problem with clogging of the die during discharge, and no problem with product yield. There was no problem with the liquid level height ratio in the polycondensation reaction tank 12. There was no problem regarding the melting point and color tone (L value) of the obtained pellets.

(Comparative Example 1)
The temperature of the heating body 20 of the polycondensation reaction tank 12 before liquid transfer is controlled at 272° C., and the reaction liquid having a temperature of 265° C. in the acetylation reaction tank is maintained while the internal temperature of the polycondensation reaction tank is 267° C. It carried out like Example 4 except having transferred the liquid.

The acetic acid distillation rate during transfer was as high as 5.1% (15 batch average value).

The polycondensation reaction time after reaching a vacuum degree of 1333 Pa (10 torr) was delayed to 76 minutes (15 batch average value). Clogging of the mouthpiece began to be seen in the sixth batch, and then the clogging of the mouthpiece became more severe. Therefore, the mouthpiece was replaced after discharging the tenth batch. Since the clogging of the mouthpiece became severer thereafter, the test was stopped at the 15th batch. The product yield (average value of 15 batches) was as low as 89.2%. The liquid level height ratio (average value of 15 batches) in the polycondensation reaction tank 12 was as high as 82.0%. The melting point of the obtained pellets (average value of 15 batches) was low, the pellets were colored, and the color tone (L value) (average value of 15 batches) was low.

(Comparative example 2)
The temperature of the heating body 20 of the polycondensation reaction tank 12 before liquid transfer is controlled to 290° C., and the reaction liquid having a temperature of 270° C. in the acetylation reaction tank is heated at a temperature of 284° C. in the polycondensation reaction tank. The procedure of Example 1 was repeated, except that the liquid was transferred and the temperature of the reaction liquid in the polycondensation reaction tank 12 was raised to 335° C. over 1.4 hours.

The acetic acid distillation rate during transfer was as high as 5.7% (average value of 10 batches).

The polycondensation reaction time after reaching a vacuum degree of 1333 Pa (10 torr) was delayed to 91 minutes (average value of 10 batches). Clogging of the mouthpiece began to be seen in the third batch, and then the clogging of the mouthpiece became more severe. Therefore, the mouthpiece was replaced after discharging the sixth batch. After that, the clogging of the mouthpiece became severe, so the test was stopped at the 10th batch. The product yield (average value of 10 batches) was as low as 87.5%. The liquid level height ratio (average value of 10 batches) in the polycondensation reaction tank 12 was as high as 87.1%. The melting point of the obtained pellets (average value of 10 batches) was low, the pellets were colored, and the color tone (L value) (average value of 10 batches) was low.

(Comparative example 3)
The temperature of the reaction liquid in the acetylation reaction tank 1 was raised to 180° C. over 180 minutes, and the temperature of the heating element 10 in the liquid transfer line 9 was controlled at 260° C. Example 12 except that the temperature of the heating element 20 of No. 12 was controlled to 290° C., and the reaction liquid having a temperature of 260° C. in the acetylation reaction tank was transferred while the internal temperature of the polycondensation reaction tank was 284° C. The same procedure as 1 was performed.

The final acetic acid distillation rate in the acetylation reactor was 3.0%/10 minutes.

After 6 minutes from the start of liquid transfer, the liquid transfer became impossible, so the liquid transfer operation was stopped, and the acetylation reaction tank 1, the liquid transfer line 9, and the polycondensation reaction tank 12 were cooled. As a result of removing the distilling line 14 of the polycondensation reaction tank 12 and inspecting the inside of the distilling line 14, a large amount of solid matter adhered and was blocked. The liquid level height ratio in the polycondensation reaction tank 12 exceeded 100.0%. The solid matter was removed and the test was conducted again. However, the same result was obtained, so the test was stopped at the second batch.

The conditions and results of each Example and Comparative Example are summarized in Table 1.

1 Acetylation reaction tank 2 Stirring blade 3 Fractionation tower 4 Distillation line 5 Reflux line 6 Condenser 7 Distilling acetic acid container 8 Raw material charging line 9 Liquid transfer line 10 Heating body 11 Liquid transfer valve 12 Polycondensation reaction tank 13 Stirring blade 14 Distillation line 15 Condenser 16 Decompression device 17 Distilled acetic acid container 18 Discharge valve 19 Discharge port 20 Heater 21 SUS rod 22 Reaction liquid adhesion part 23 Reaction liquid adhesion height 24 Polycondensation reaction vessel inner wall height 25 thermometer

Claims (7)

A method for producing a liquid crystalline polyester resin containing a structural unit produced from hydroquinone using a production apparatus having at least an acetylation reaction tank and a polycondensation reaction tank, comprising reacting from the acetylation reaction tank to the polycondensation reaction tank In the step of transferring the liquid, the internal temperature of the polycondensation reaction tank is set to 250 to 264° C., and the temperature of the reaction liquid in the acetylation reaction tank is set in the range of −30 to −3° C. A method for producing a liquid crystalline polyester resin which starts a liquid. In the liquid transfer step, the temperature of the heating body of the polycondensation reaction tank on the surface in contact with the reaction liquid is set in the range of -20 to -1°C with respect to the temperature of the reaction liquid in the acetylation reaction tank, and then the liquid transfer is performed. The method for producing a liquid crystalline polyester resin according to claim 1, which is started. The method for producing a liquid crystalline polyester resin according to claim 1, wherein the acetic acid distillation rate in the liquid transfer step is 5% or less. The method for producing a liquid crystalline polyester resin according to claim 1, wherein the liquid transfer is started after the acetic acid distillation rate in the acetylation reaction tank is 2.5%/10 minutes or less. In the liquid transfer step, the temperature of the heating element of the liquid transfer line on the surface in contact with the reaction liquid is set in the range of −20 to +10° C. with respect to the temperature of the reaction liquid in the acetylation reaction tank, and then the liquid transfer is started. A method for producing the liquid crystalline polyester resin according to claim 1. The method for producing a liquid crystalline polyester resin according to claim 1, which is a batch continuous polymerization method. The liquid crystalline polyester resin obtained is a structural unit produced from p-hydroxybenzoic acid, a structural unit produced from 4,4′-dihydroxybiphenyl, a structural unit produced from hydroquinone, a structural unit produced from terephthalic acid, and isophthalic acid. The method for producing a liquid crystalline polyester resin according to any one of claims 1 to 6, which is a liquid crystalline polyester resin composed of a structural unit produced from.

Images