JP6880917B2 - Manufacturing method of liquid crystal polyester resin - Google Patents

Description

In the present invention, a molten liquid crystal polyester resin is discharged as a strand group through a die head and a mouthpiece of a discharge port (hereinafter, the mouthpiece of the discharge port may be simply referred to as a mouthpiece) to be liquid crystal. The present invention relates to a method for producing a liquid crystal polyester resin, which is excellent in discharge stability and can improve continuous batch productivity and pellet quality in a process for producing a polyester resin.

Demand for liquid crystal polyester resins is expanding mainly for small precision molded products for electrical and electronic applications, taking advantage of their excellent heat resistance, fluidity, and electrical characteristics. Further, in recent years, paying attention to its thermal stability and high thermal dimensional accuracy, studies have been made on using it as a supporting base material for heat-generating parts, such as a liquid crystal display supporting base material for OA equipment and mobile phones, and structural parts for lamps.

The most suitable method for producing a liquid crystal polyester resin is to discharge as a strand group through a die head having a valve and a mouthpiece of a discharge port having a plurality of base holes, cool and solidify the strand group, and cut with a cutter. It is commonly used. However, unlike other thermoplastic resins, the liquid crystal polyester resin has a high melting point, so it is necessary to maintain the die head temperature at a high temperature, and the polymer remaining in the die head has a thermal history until the next batch is discharged. As a result, it becomes highly crystallized, becomes a carbide and becomes a foreign substance, and the foreign substance increases to block the base portion, resulting in a decrease in continuous productivity and a deterioration in ejection property.

As a method of improving discharge stability and pellet quality, when cutting from the mouthpiece into a strand shape with a cutter, the ratio of the mouthpiece hole diameter to the perforated plate hole diameter is specified to continuously discharge stability and batch polymerization. A method for improving productivity (continuous batch productivity) and pellet quality is being studied (see Patent Document 1).

Further, after discharging the polymer in the polycondensation reaction, the polycondensation reaction tank is cooled under specified conditions and the next raw material is charged to suppress the mixing of foreign substances in the residual polymer and improve the pellet yield. Is being studied (Patent Document 2).

Furthermore, for the purpose of reducing the residual polymer in the polycondensation reaction tank and the die head after the discharge is completed, the batch type is performed by re-discharging at a specified gauge pressure or by press-fitting an inert gas into the die head to perform the discharge operation. Methods for increasing the productivity of polymerization and improving the quality of the polymer have been studied (see Patent Documents 3 and 4).

On the other hand, a method of efficiently taking out from the polycondensation reaction tank by controlling the temperature of the liquid crystal polyester resin in the discharge pipe within a certain range with respect to the temperature of the liquid crystal polyester resin at the time of discharge has been studied. (See Patent Document 5).

International Publication No. 2015/152175 (Claims) Japanese Patent Application Laid-Open No. 5-255495 (Claims) Japanese Unexamined Patent Publication No. 2011-93971 (Claims) Japanese Unexamined Patent Publication No. 2001-151893 (Claims) JP-A-2010-106264 (Claims)

However, in the methods of Patent Documents 1 and 2, the temperature control conditions of the die head are not specifically described, and sufficient effects for improving continuous batch productivity and ejection performance cannot be exhibited.

Further, in the methods of Patent Documents 3 and 4, the work becomes complicated and the operation takes time, so that the work man-hours increase and the manufacturing cost deteriorates.

Further, in the method of Patent Document 5, when the device having a die head and a base used for producing the liquid crystal polyester resin is replaced, the effect intended by the present invention cannot be exhibited.

INDUSTRIAL APPLICABILITY The present invention provides excellent discharge stability, continuous batch productivity and pellet quality in a process of producing a liquid crystal polyester resin by discharging a molten liquid crystal polyester resin as a strand group via a die head and a mouthpiece. Provided is a method for producing a liquid crystal polyester resin, which can be improved.

The present inventors have described the above in the method for producing a liquid crystal polyester resin by a batch type polymerization method in which a reaction tank feeds a resin into a die head via a valve and discharges the die head from the die head through a discharge port so as to form a strand group. By maintaining the temperature (T1) at the start of ejection of the die head and the temperature (T2) waiting from the end of ejection of the die head to the next ejection within a specific range, the formation of the refractory polymer in the die head is suppressed. It was found that it was possible to prevent clogging of the base and improve continuous batch productivity. Furthermore, it was found that the discharge property of the strand can be improved and the pellet quality can be improved.

That is, in the present invention , the raw material monomer and anhydrous acetic acid are charged into the reaction tank 1, the acetylation reaction is carried out, and then the reaction solution of the reaction tank 1 is transferred to the reaction tank 2 through the transition tube connected to the reaction tank 2 to remove the reaction solution. a manufacturing method of a liquid crystal polyester performing acetate polycondensation, a liquid crystalline polyester resin obtained raw material melt polycondensation in the reaction vessel 2 was fed into the die head from the reactor 2 via the valve In the method for producing a liquid crystal polyester resin by a batch type polymerization method in which the die head is discharged from the die head through a discharge port so as to form a strand group, the temperature (T1) at the start of discharge of the die head is set to the melting point of the liquid crystal polyester resin (T1). Tm) above, the melting point (Tm) + 40 ° C. or less, during the discharge so as to form a strand group through a discharge port from said die head while maintaining the temperature of the die head at the discharge starting temperature (T1), said die head A method for producing a liquid crystal polyester resin, which maintains the waiting temperature (T2) from the end of discharge to the next discharge in the range of -25 ° C to -3 ° C with respect to the temperature (T1) at the start of discharge of the die head. is there.

According to the liquid crystal polyester resin manufacturing apparatus and manufacturing method of the present invention, in the step of manufacturing the liquid crystal polyester resin by discharging the molten liquid liquid polyester resin as a strand group via the die head and the base, the inside of the die head It is possible to suppress the formation of the high melting point polymer of the above, prevent clogging of the base, and improve the continuous batch productivity. Further, the discharge property can be improved, and the pellet quality can be improved.

FIG. 1 is a schematic configuration diagram illustrating a liquid crystal polyester resin manufacturing apparatus including a die head to which a valve is connected. FIG. 2 is a schematic view illustrating a method of controlling the temperature of the die head in a case where the set temperature of the die head is two points. FIG. 3 is a schematic view illustrating a method of controlling the temperature of the die head in a case where the set temperature of the die head is four points. FIG. 4 is a schematic view illustrating a method of controlling the temperature of the die head in a case where the temperature rise and cooling gradient of the die head are defined.

The liquid crystal polyester resin of the present invention is a resin that forms an anisotropic molten phase, and examples thereof include a liquid crystal polyester resin having an ester bond such as a liquid crystal polyester and a liquid crystal polyester amide.

As the structural unit constituting the liquid crystal polyester resin, for example, a structural unit selected from an aromatic oxycarbonyl unit, an aromatic and / or an aliphatic dioxy unit, an aromatic and / or an aliphatic dicarbonyl unit and the like is preferable.

Examples of the aromatic oxycarbonyl unit include structural units produced from p-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid and the like, and p-hydroxybenzoic acid is preferable. Examples of the aromatic or aliphatic dioxy unit include 4,4'-dihydroxybiphenyl, hydroquinone, 3,3', 5,5'-tetramethyl-4,4'-dihydroxybiphenyl, t-butylhydroquinone, and phenylhydroquinone. , 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 2,2-bis (4-hydroxyphenyl) propane and 4,4'-dihydroxydiphenyl ether, ethylene glycol, 1,3-propylene glycol, 1,4- Examples thereof include structural units produced from butanediol and the like, and 4,4'-dihydroxybiphenyl and hydroquinone are preferable. Examples of the aromatic or aliphatic dicarbonyl unit include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 1,2-bis (phenoxy) ethane-4,4'. Examples of structural units produced from -dicarboxylic acid, 1,2-bis (2-chlorophenoxy) ethane-4,4'-dicarboxylic acid, 4,4'-diphenylether dicarboxylic acid, adipic acid, sebacic acid, etc., include terephthalic acid. Acids and isophthalic acids are preferable.

Specific examples of the liquid crystal polyester resin include a structural unit produced from p-hydroxybenzoic acid, a structural unit produced from 4,4'-dihydroxybiphenyl, a structural unit produced from hydroquinone, and a structural unit produced from terephthalic acid and / or isophthalic acid. Liquid polyester resin consisting of the above structural units, structural units produced from p-hydroxybenzoic acid, structural units produced from ethylene glycol, structural units produced from 4,4'-dihydroxybiphenyl, structural units produced from hydroquinone, terephthalic acid. Liquid polyester resin consisting of structural units made of acid and / or isophthalic acid, structural units made of p-hydroxybenzoic acid, structural units made of ethylene glycol, structural units made of 4,4'-dihydroxybiphenyl, Liquid polyester resin consisting of structural units made of terephthalic acid and / or isophthalic acid, structural units made of p-hydroxybenzoic acid, structural units made of hydroquinone, structural units made of 4,4'-dihydroxybiphenyl, Examples thereof include a liquid crystal polyester resin composed of a structural unit produced from 2,6-naphthalenedicarboxylic acid and a structural unit produced from terephthalic acid. The preferred combination of these is a structural unit produced from p-hydroxybenzoic acid, a structural unit produced from hydroquinone, a structural unit produced from 4,4'-dihydroxybiphenyl, a structural unit produced from terephthalic acid and / or isophthalic acid. From a combination consisting of, a structural unit produced from p-hydroxybenzoic acid, a structural unit produced from ethylene glycol, a structural unit produced from 4,4'-dihydroxybiphenyl, a structural unit produced from terephthalic acid and / or isophthalic acid. The combination is exemplified.

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

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

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

The amount of copolymerization of the structural units (I), (II), (III), (IV) and (V) is arbitrary. However, in order to bring out the characteristics of the liquid crystal polyester resin, the following copolymerization amount is preferable. The structural unit (I) is preferably 65 to 80 mol% with respect to the total of the structural units (I), (II) and (III). More preferably, it is 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% with respect to 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 unit constituting the polymer main chain excluding the terminal is equimolar. For this reason, the requirement of "substantially equimolar" can be satisfied even in a mode in which the molars are not necessarily equimolar when the structural units constituting the ends are included.

Above all, it is preferable that the structural unit (I) is a liquid crystal polyester resin in which the total of all five structural units is 30 mol% or more. When it is 30 mol% or more, it is preferable because the heat resistance targeted by the liquid crystal polyester resin can be obtained.

The liquid crystal 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). Compounds, aliphatic dicarboxylic acid compounds such as adipic acid, azelaic acid, sebacic acid and dodecandic acid, alicyclic dicarboxylic acid compounds such as hexahydroterephthalic acid, chlorohydroquinone, 3,4'-dihydroxybiphenyl, 4,4' Aromatic diol compounds such as −dihydroxydiphenylsulfone, 4,4′-dihydroxydiphenylsulfide, 4,4′-dihydroxybenzophenone, 3,4′-dihydroxybiphenyl, propylene glycol, 1,4-butanediol, 1,6- Liquidity and properties of aliphatic diol compounds such as hexanediol, neopentylglycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, alicyclic diol compounds, m-hydroxybenzoic acid, polyethylene terephthalate, etc. It may be held within a range that does not impair.

Examples of the raw material of the liquid crystal polyester resin include aromatic hydroxycarboxylic acid compounds, diol compounds, dicarboxylic acid compounds, and monomers having an amino group.

Of these, aromatic hydroxycarboxylic acid compounds such as p-hydroxybenzoic acid, diol compounds such as 4,4'-dihydroxybiphenyl, hydroquinone and ethylene glycol, and aromatic dicarboxylic acid compounds such as terephthalic acid and isophthalic acid are preferable.

Examples of the monomers used in addition to hydroquinone, ethylene glycol, p-hydroxybenzoic acid, 4,4'-dihydroxybiphenyl, terephthalic acid and isophthalic acid include the following monomers. Examples of the aromatic hydroxycarboxylic acid compound include 6-hydroxy-2-naphthoic acid, and examples of the aromatic dicarboxylic acid compound include 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 1, 2-Bis (phenoxy) ethane-4,4'-dicarboxylic acid, 1,2-bis (2-chlorophenoxy) ethane-4,4'-dicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, etc. are listed respectively. Be done. Examples of the aromatic diol compound include resorcinol, t-butylhydroquinone, phenylhydroquinone, chlorohydroquinone, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 3,4'-dihydroxybiphenyl, and 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.

For example, in the production of the liquid crystal polyester resin, the following production method is preferably mentioned. The following production method has been described by taking the synthesis of a liquid crystal polyester resin composed of p-hydroxybenzoic acid, 4,4'-dihydroxybiphenyl, hydroquinone, terephthalic acid and isophthalic acid as an example, but as a copolymerization composition. Is not limited to these, and each can be replaced with polyethylene terephthalate, other hydroxycarboxylic acid compound, aromatic diol compound or aromatic dicarboxylic acid compound, and produced according to the following method.

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

Hereinafter, the method for producing the liquid crystal polyester resin of the present invention will be described in detail.

For example, a predetermined amount of a monomer mixture and acetic anhydride are charged in a reaction vessel equipped with a raw material input port, a stirring blade, a rectification tube, a distilling tube, and a decompression device and a discharge port at the bottom, and in a nitrogen gas atmosphere. Heat with stirring and acetylate the hydroxyl groups with reflux. After that, the temperature is raised to a predetermined temperature while acetic acid is distilled from the reaction vessel via the distilling tube, and when the specified amount of acetic acid is distilled off, the reaction vessel is depressurized and the acetic acid generated by the polycondensation reaction is performed. To distill. After distilling acetic acid, a deacetic acid polycondensation reaction is carried out until a specified stirring torque is reached. When the deacetic acid polycondensation reaction is completed, stirring is stopped, the reaction vessel is pressurized with nitrogen, and the polymer is discharged in a strand shape via the die head connected to the bottom of the reaction vessel and through the mouthpiece hole of the discharge port. , The obtained strands are pelletized with a cutting device.

In the present invention, the number of reaction tanks is not particularly limited, and the reaction can be carried out in one tank or two or more reaction tanks. An example of a preferable method in the case of performing in two tanks is as follows. First, a raw material monomer and acetic anhydride are charged into the reaction tank 1 (also referred to as an acetylation reaction tank), an acetylation reaction is carried out, and then an oligomerization reaction is carried out to a predetermined temperature and a predetermined amount of acetic acid distilled. Next, the reaction solution of the reaction tank 1 is transferred to the reaction tank 2 through a transfer tube connected to the reaction tank 2, and deacetic acid polycondensation is further performed to a predetermined temperature and a predetermined amount of acetic acid distillate, and then the reaction tank 2 is depressurized. The polycondensation is further advanced, and the reaction is terminated when a predetermined stirring torque is reached. In the present invention, when the reaction tank is carried out in one tank or in two or more tanks, the reaction tank having the die head and the discharge port and finally discharging the polymer is referred to as a polycondensation reaction tank.

The liquid crystal polyester resin of the present invention is produced by a batch polymerization method. In the batch polymerization method referred to here, as described above, a predetermined amount of a monomer mixture and acetic anhydride for one batch are charged into an acetylation reaction tank, and when the predetermined reaction is completed, the polymer is transferred to a polycondensation reaction tank. When the liquid is liquid and the predetermined reaction is completed, the polymer is discharged while pelletizing, and in the second batch, a predetermined amount of the monomer mixture and acetic anhydride for one batch are charged into the acetylation reaction tank in the same manner as described above. Similarly, a predetermined reaction is to be carried out. 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 monomer mixture in the next batch with a certain amount of the reaction solution left in the acetylation reaction tank. The batch polymerization method also includes a method of charging acetic anhydride and a method of performing both an acetylation reaction and a polycondensation reaction in a single reaction tank without using an acetylation reaction tank.

The amount of acetic anhydride used in the acetylation reaction is preferably 1.00 to 1.20 molar equivalents with respect to the total amount of phenolic hydroxyl groups in the liquid crystal polyester resin raw material used. More preferably, it is 1.03 to 1.16 molar equivalents. The acetylation reaction is preferably carried out while refluxing 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 reaches a specific range.

In the past, it was common to prepare monomers so that the total number of moles of terephthalic acid and isophthalic acid and the total number of moles of 4,4'-dihydroxybiphenyl and hydroquinone were equal. Due to its high sublimation properties, hydroquinone may be added in excess in the range of 2 to 15 mol% with respect to the amount of charged monomer to be equimolar. By doing so, the amount of hydroquinone monomer deficient due to sublimation of hydroquinone can be suppressed, the target polymerization rate can be obtained, and the increase in the amount of gas during heating retention of the polymer can be suppressed, which is preferable.

As an apparatus for the acetylation reaction, for example, a reaction vessel equipped with a reflux tube, a rectification column, and a condenser can be used. The reaction time for acetylation is roughly 1 to 5 hours, but the time until the residual amount of the monoacetylated product of the aromatic diol reaches a specific range depends on the liquid crystal polyester resin raw material used and the reaction temperature. Is also different. The acetylation reaction is preferably 1.0 to 2.5 hours, and the higher the reaction temperature, the shorter the time, and the larger the molar ratio of acetic anhydride to the phenolic hydroxyl group terminal, the shorter the reaction. Therefore, it is preferable.

When raising the temperature to a predetermined temperature while distilling acetic acid, it is preferable to raise the temperature at the top 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 temperature at the top of the column is too low, a large amount of unreacted acetic anhydride will remain in the system, which may cause coloration of the polymer and increase the amount of gas during heat retention. preferable. Further, by setting the column top temperature to 150 ° C. or lower, the monomers are distilled out of the system, the desired composition is deviated, and the polymerization rate is not lowered. In this case, the distillate acetic acid contains excess acetic anhydride and monomers, but the mass% of the monomers excluding acetic anhydride and acetic anhydride is preferably 1% by mass or less, preferably 0.5% by mass or less. More preferable.

The deacetic acid polycondensation reaction is preferably a melt polymerization method in which the liquid crystal polyester resin is reacted under reduced pressure at a melting temperature to complete the polymerization reaction. The melt polymerization method is an advantageous method for producing a uniform polymer, and is preferable because a polymer with a smaller amount of gas generated can be obtained.

The final polymerization temperature is preferably a melting point of about +20 ° C., preferably 370 ° C. or lower. The degree of reduced pressure at the time of 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, the polymerization time from when the degree of reduced pressure becomes 1333 Pa or less until the specified polymerization stirring torque is detected and the polymerization is completed is 0.3 to 1.0 hours.

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

In the method for producing a liquid crystal polyester resin of the present invention, a liquid crystal polyester resin obtained by melting and polycondensing a raw material in a reaction tank is supplied from the reaction tank into a die head via a valve and discharged from the die head. In the method for producing a liquid crystal polyester resin by a batch type polymerization method in which the resin is discharged so as to form a strand group through the outlet, the temperature (T1) at the start of discharge of the die head is set to be equal to or higher than the melting point (Tm) of the liquid crystal polyester resin. While discharging from the die head through the discharge port so as to form a strand group, the temperature of the die head is maintained at the temperature at the start of discharge (T1), and the temperature during standby from the end of discharge of the die head to the next discharge ( This is a method of holding T2) in the range of −25 ° C. to -3 ° C. with respect to the temperature (T1) at the start of ejection of the die head.

In the method for producing a liquid crystal polyester resin in the present invention, when the discharge of the polymer in the polycondensation reaction tank is completed, the temperature of the die head is controlled at a temperature (T2) lower than the temperature (T1) at the start of discharge for a certain period of time. By the start of discharge of the next batch, the temperature is raised again to a temperature (T1) higher than the temperature (T2) after the end of discharge, and control is performed for a certain period of time so as to maintain the temperature (T1) until the end of discharge.

In the present invention, the temperature control method of the die head is not particularly limited, but a method of cooling or raising the temperature with a specified gradient and a method of changing the set temperature of the die head a plurality of times at a specified timing can be mentioned. However, among them, a method of changing the set temperature of the die head a plurality of times is preferable, and a method of changing the set temperature of 2 to 3 points is more preferable. With this method, temperature control is relatively easy. In particular, when the temperature (T2) after the end of discharge of the die head is controlled by cooling or raising the temperature of the die head with a specified gradient, the minimum temperature during the temperature control is T2. adjust.

The temperature (T1) at the start of ejection of the die head is equal to or higher than the melting point (Tm) of the liquid crystal polyester resin. If it is less than the melting point (Tm), the residual polymer in the die head may solidify and clog the mouthpiece hole, or the polymer may solidify during ejection and stable ejection may not be possible. It is preferable that the temperature (T1) at the start of ejection of the die head is set to be equal to or higher than the melting point, and the temperature of the die head is kept above the melting point (Tm) until the ejection of all the polymers is completed. Further, the temperature T1 is not particularly limited as long as it is equal to or higher than the melting point, but the residual polymer in the die head may be altered to have a high melting point and become a foreign substance, the foreign substance may cause clogging of the mouthpiece, or the residual polymer due to decomposition gas. From the viewpoint of suppressing scattering, the upper limit thereof is preferably a melting point of + 40 ° C., more preferably a melting point of + 35 ° C.

The temperature (T2) waiting from the end of ejection of the die head to the next ejection is maintained in the range of −25 ° C. to -3 ° C. with respect to the temperature (T1) at the start of ejection of the die head. More preferably, it is in the range of −20 ° C. to −5 ° C. with respect to T1. If the temperature is lower than -25 ° C with respect to T1, the residual polymer in the die head may be insufficiently melted to cause clogging of the mouthpiece, the residual polymer may have a high melting point and become a foreign substance, and the quality of the polymer may deteriorate. There is a fear. If the temperature is higher than -3 ° C with respect to T1, the residual polymer in the die head may be insufficiently melted and clogging of the mouthpiece may occur, or the residual polymer in the die head may have a high melting point, resulting in a decrease in continuous batch productivity and polymer quality. May decrease.

The temperature (T2) after the end of ejection of the die head is preferably maintained in the range of −5 ° C. to + 25 ° C. with respect to the melting point (Tm) of the liquid crystal polyester resin, and more preferably with respect to the melting point (Tm). It is in the range of 0 ° C (that is, a temperature equal to the melting point (Tm)) to + 20 ° C. If the temperature is lower than -5 ° C with respect to the melting point (Tm), the residual polymer in the die head may be completely solidified, which may take a long time to remelt, or the unmelted polymer may block the mouthpiece. The residual polymer in the die head may change in quality and have a high melting point, resulting in foreign matter. If the temperature is higher than + 25 ° C. with respect to the melting point (Tm), the residual polymer in the die head may be altered to have a high melting point and become a foreign substance, the foreign substance may cause clogging of the mouthpiece, and the decomposition gas may cause the residual polymer to gain momentum. There is a risk of blowing out and scattering. Even if the temperature (T2) after the end of ejection of the die head is equal to or lower than the melting point (Tm) of the liquid crystal polyester resin, the residual polymer in the die head needs to be in a molten state and is partially solidified. Even in this case, if the solidified portion of the residual polymer in the die head is 50% or less, it is in a molten state.

The temperature holding time of the die head preferably satisfies the relationship of the following formula (1), and more preferably satisfies the following formula (2).
Equation (1): 0.05 ≦ (t1 / (t1 + t2)) ≦ 0.5
Equation (2): 0.1 ≦ (t1 / (t1 + t2)) ≦ 0.4

In the above formula, t1 represents the die head temperature holding time (hr) at the temperature T1 in one cycle of the batch polymerization, and t2 represents the die head temperature holding time (hr) at the temperature T2 in one cycle of the batch polymerization. The t1 (die head temperature holding time (hr) at the temperature T1 in one cycle of batch polymerization) in the present invention is T1 of the next batch from the time when the temperature rise is started from T2 of the previous batch to T1. It represents the time (hr) from the time when cooling is started so as to become T2. Further, t2 (die head temperature holding time (hr) at temperature T2 in one cycle of batch polymerization) is increased from T2 to T1 in the next batch from the time when cooling is started from T1 to T2. It represents the time (hr) between the time when the temperature was started. By setting the temperature holding time (t1 / (t1 + t2)) of the die head to 0.05 or more, it is possible to prevent the residual polymer in the die head from being insufficiently melted and causing clogging of the base. Further, when the value is 0.5 or less, it is possible to prevent the residual polymer in the die head from having a high melting point and becoming a foreign substance, and to prevent the residual polymer from being vigorously blown out and scattered by the decomposition gas.

The one cycle of batch type polymerization referred to here is the cycle time (required time) between batches in which the same work or process is performed in the process of repeating batch type polymerization. For example, from the start of ejection of the first batch. The time required to start discharging the second batch is called one cycle. That is, one cycle means the total time of t1 and t2, and (t1 / (t1 + t2)) represents the ratio of the temperature holding time of the die head at the temperature T1 to one cycle time. The work or process that is the standard for one cycle is not limited to the time when the discharge is started, and even if the time required for one cycle is not necessarily the same due to the repetition of batch polymerization, it is regarded as one cycle for batch polymerization. .. An example of the relationship between the die head temperature and t1 and t2 is shown in FIG.

In order to set (t1 / (t1 + t2)) in the present invention in the range of 0.05 or more and 0.5 or less, one cycle time ((t1 + t2) (hr)) may be adjusted or t1 (hr) may be adjusted. .. Specifically, in the case of adjusting the one cycle time, the timing of charging the raw material monomer and acetic anhydride into the reaction vessel may be adjusted, or the transition start timing may be adjusted. Further, in the case of adjusting t1, the timing at which the temperature rise from T2 to T1 in the previous batch is started may be adjusted, the deacetic acid polycondensation reaction time may be adjusted, or the discharge time may be adjusted. FIG. 4 shows an example of the relationship between the die head temperature and t1 and t2 when t1 and t2 are adjusted.

The temperature of the die head can be preheated at the temperature T1 before the start of discharge so that the temperature becomes T1 at the start of discharge. The time (preheating time) for preheating the temperature of the die head to T1 before discharging is preferably 4 hours or less from the viewpoint of suppressing the deterioration of the residual polymer in the die head and the scattering of the residual polymer due to the decomposition gas. More preferably, it is within 3 hours.

It is also possible to change the temperature T1 to the temperature T1'in a stepwise manner during the temperature holding time t1 of the die head. In this case, the temperature T1'is not particularly limited as long as it is at least the melting point (Tm), but from the viewpoint of suppressing deterioration of the residual polymer in the die head, it is preferably at least the melting point (Tm) and the temperature T1 ± 8 ° C. T1 ± 5 ° C. is more preferable. Further, the temperature T1 may be changed a plurality of times after the start of discharge. It is also possible to change the temperature T2 to the temperature T2'during the temperature holding time t2 of the die head. In that case, the temperature held for the longest time between t2 is defined as T2. In this case, the temperature T2'is not particularly limited as long as it is in the range of -25 ° C to -3 ° C with respect to the temperature T1, but from the viewpoint of suppressing deterioration of the residual polymer in the die head, the temperature T2'is-with respect to the temperature T1. The temperature is preferably 25 ° C. to -3 ° C. and the temperature T2 ± 8 ° C., more preferably the temperature T2 ± 5 ° C. Further, the temperature T2 may be changed a plurality of times. FIG. 3 shows an example in which the die head temperatures T1 and T2 are changed a plurality of times.

The temperature control of the die head of the present invention is effective in the process of repeating batch polymerization, but for example, when a standby time of one cycle time or more is required for process trouble or production volume adjustment. In a state where the residual polymer in the die head is reduced as much as possible, the temperature (T2) after the end of ejection of the die head is controlled to be equal to or lower than the temperature lowering crystallization temperature (Tc) of the liquid crystal polyester resin, and the residual polymer in the die head is solidified. It is preferable to hold at. By controlling in this way, deterioration of the residual polymer in the die head and high melting point can be suppressed, which is preferable. The temperature-decreasing crystallization temperature of the liquid crystal polyester resin in the present invention is measured by the following method. After observing the heat absorption peak temperature (Tm1) observed when the liquid crystal polyester resin is measured with a differential scanning calorimeter at a temperature rise condition of 20 ° C./min from room temperature, the heat absorption peak temperature (Tm1) + 20 ° C. After holding for 5 minutes, the exothermic peak temperature observed when measured under the temperature decreasing condition of 20 ° C./min is defined as the temperature decreasing crystallization temperature (Tc).

As shown in FIG. 1, the molten liquid crystal polyester resin in which the polycondensation reaction is completed in the polycondensation reaction tank 1 is supplied to the die head 8 with the on-off valve of the discharge valve 7 open, and is supplied to the slide plate valve. With the 11 open, the resin is discharged so as to form a strand group through the discharge port plate 10 having a plurality of base holes. The strands are cooled and solidified and cut into pellets by a cutting device.

In the production method in the present invention, one or more valves are provided between the polycondensation reaction tank 1 and the die head 8 or at an upper position of the die head 8. It is preferable to have one valve from the viewpoint of cost and maintenance. The form of the valve is not particularly limited, but a ball valve or a push-in valve is preferably used, and a push-in valve is more preferably used because the sealing property and operability of the polymer are good.

In FIG. 1, the position of the die head 8 is located at the bottom of the polycondensation reaction tank 1, and is connected to the polycondensation reaction tank 1 with the discharge valve 7 sandwiched between them. In the case, it is directly connected to the bottom of the polycondensation reaction tank 1.

Since the die head 8 heats the polymer that passes or stays inside, the die head 8 has a heating body, and the installation position and type of the heating body are not particularly limited. Even if the die head 8 is attached to the inner wall surface of the die head 8, the wall of the die head 8 is used. It may be embedded inside the die head, attached to the outer wall surface of the die head to indirectly heat the inner wall surface through the wall of the die head 8, or the discharge valve 7 portion may be heated. Examples of the type of heating element include a method of heating by covering with a coil, a jacket, and a band-shaped heating element. Among these, the method of attaching the jacket 9 to the outer wall surface is preferable in that the heating range can be heated at a uniform temperature. As a method of generating heat of the heating body, a method of circulating in the coil or the jacket 9 with a vapor or a liquid heat medium, a method of heating the heating body with a heating wire, or the like is used. A method of circulating with a vapor or a liquid heat medium is preferable, and a method of circulating with a pump with a liquid heat medium inside the jacket 9 is preferable. With this method, the temperature can be controlled stably.

The die head temperatures T1 and T2 of the present invention refer to the internal temperature of the die head when a temperature element or the like is provided inside the die head and the temperature can be measured. Refers to the control temperature of.

The shape of the die head 8 is preferably a shape in which the liquid crystal polyester resin becomes wider in the direction of flow toward the discharge port.

The die head 8 is provided with a discharge port plate 10 having a plurality of base holes. Further, it is preferable to provide an on-off valve under the discharge port plate 11 for the purpose of encapsulating the residual polymer and keeping the mouthpiece hole warm. The shape of the on-off valve is not particularly limited and is generally known and has no problem. Specific examples thereof include a slit valve, a ball valve, and a slide plate valve 11. In this case, it is also possible to function as an on-off valve by crimping the mouthpiece hole with a valve body plate or the like until the next batch is discharged, and removing the valve body plate at the time of discharging to perform the discharge. The shape of the on-off valve is preferably a slit valve or a slide plate valve 11, and is excellent in terms of operation and maintenance.

The diameter of the mouthpiece hole of the discharge port is preferably 3 mm to 6 mm. It is more preferably 3.5 mm to 6.0 mm, and most preferably 4.0 mm to 5.5 mm. If the diameter of the base hole is less than 3 mm, the pressure loss of the base portion becomes large, a higher discharge pressure is required, the strands are thin, curved, and meandering, and good pellets cannot be obtained. Further, if the diameter of the base hole is larger than 6 mm, the strand group becomes thick and rigid, causing vertical fluttering, which may cause poor flow of the strand group, and the number of continuous ball pellets and uncut pellets increases, so that good pellets can be obtained. There is no fear.

The number of mouthpiece holes in the discharge port is preferably 20 or more, and more preferably 40 or more. This is because, in order to obtain an excellent pellet shape, it is necessary that the residual polymer stays in the die head in a small amount and the entire strand group runs stably, and the number of base holes is large, that is, the strand group is large. In some cases, a more stable liquid crystal polyester resin can be obtained.

The arrangement of the mouthpiece holes of the discharge port is not particularly limited, but it is preferable to arrange the strands so that the strands do not overlap when the strands are picked up. A method of arranging in a shape can be mentioned, but in the case of a staggered shape, the strand groups do not overlap and the target number of base holes can be obtained, which is preferable. Further, it is preferable to provide the mouthpiece holes close to both ends of the die head because residual polymer is less likely to accumulate at both ends of the mouthpiece.

After the polycondensation reaction is completed, in order to take out the obtained molten resin from the reaction vessel, the inside of the reaction vessel is pressurized to, for example, about 0.02 to 0.5 MPa at the temperature at which the liquid crystal polyester resin melts, and the molten resin is weighted. It is discharged in a strand shape from the discharge port of the die head connected to the lower part of the condensation reaction tank. It is preferable that the strand group is discharged into a trough through which cooling water is flowed, cooled in cooling water to solidify, and cut into pellets with a cutter to obtain a liquid crystal polyester resin. There is no particular problem with the discharged strand even if the central part is in a semi-molten state, and when the pellet is discharged in the form of pellets with a cutter, the strands are solidified to the extent that the pellets do not fuse with each other and no whisker-like protrusions are formed. If it is possible, there is no problem.

When producing the liquid crystal polyester resin of the present invention, it is also possible to complete the polycondensation reaction by a solid phase polymerization method. For example, the polymer or oligomer of the liquid crystal polyester resin of the present invention is pulverized with a pulverizer, and the liquid crystal polyester resin has a melting point of −50 ° C. to a melting point of −5 ° C. for 1 to 50 hours under a nitrogen stream or under reduced pressure. Examples thereof include a method of heating and polycondensing to a desired degree of polymerization to complete the reaction. The solid phase polymerization method is an advantageous method for producing a polymer having a high degree of polymerization.

The melt viscosity of the liquid crystal polyester resin obtained in the present invention is preferably 10 to 500 Pa · s. More preferably, it is 12 to 200 Pa · s. The melt viscosity is a value measured by an elevated flow tester under the conditions of melting point (Tm) + 10 ° C. to + 20 ° C. and shear rate 1000 [1 / sec].

The melting point of the liquid crystal polyester resin in the present invention is not particularly limited, but it is preferable to combine the copolymerization components so that the temperature becomes 280 ° C. or higher for use in high heat resistance applications. The melting point (Tm) of the liquid crystal polyester resin in the present invention is measured by the following method. After observing the endothermic peak temperature (Tm1) observed when the liquid crystal polyester resin is measured with a differential scanning calorimeter at a temperature rising condition of 20 ° C./min from room temperature, the endothermic peak temperature (Tm1) + 20 ° C. After holding for 5 minutes, the temperature is once cooled to room temperature under the condition of lowering temperature of 20 ° C./min, and the endothermic peak temperature (Tm2) observed when measured again under the condition of raising temperature of 20 ° C./min is defined as the melting point (Tm). ..

In the present invention, it is possible to further add a filler in order to impart mechanical strength and other characteristics of the liquid crystal polyester resin. The filler is not particularly limited, but a fibrous, plate-like, powder-like, or granular-like filler can be used. Specifically, for example, glass fiber, PAN-based or pitch-based carbon fiber, stainless fiber, metal fiber such as aluminum fiber or brass fiber, organic fiber such as aromatic polyamide fiber or liquid crystal polyester fiber, gypsum fiber, ceramic fiber. , Asbestos fiber, zirconia fiber, alumina fiber, silica fiber, titanium oxide fiber, silicon carbide fiber, rock wool, basalt fiber, titanium oxide whisker, potassium titanate whisker, barium titanate whisker, aluminum borate whisker, silicon nitride whisker, etc. Fibrous, whisker-like filler, mica, talc, kaolin, silica, glass beads, glass flakes, glass microballoons, clay, molybdenum disulfide, wallastenite, titanium oxide, zinc oxide, calcium polyphosphate and graphite powder. , Granular or plate-like filler. The above-mentioned filler used in the present invention can also be used by treating its surface with a known coupling agent (for example, a silane-based coupling agent, a titanate-based coupling agent, etc.) or another surface treatment agent. ..

Among these fillers, glass fiber is particularly preferably used from the viewpoint of the 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, a long fiber type or a short fiber type chopped strand or milled fiber can be selected and used. Further, two or more of these can be used in combination. As the glass fiber used in the present invention, a weakly alkaline glass fiber is excellent in terms of mechanical strength and can be preferably used. Further, the glass fiber is preferably coated with an epoxy-based, urethane-based, acrylic-based coating or a converging agent, and the epoxy-based one is particularly preferable. Further, it is preferably treated with a silane-based or titanate-based coupling agent or other surface treatment agent, and an epoxy silane or aminosilane-based coupling agent is particularly preferable.

The glass fiber 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 blending amount of the filler is usually 30 to 200 parts by weight, preferably 40 to 150 parts by weight, based on 100 parts by weight of the liquid crystal polyester resin.

Furthermore, the liquidaceous polyester resins of the present invention include antioxidants and heat stabilizers (eg, hindered phenols, hydroquinones, phosphites and their substitutes), UV absorbers (eg resorcinol, salicylate), subphosphorus. Coloring containing anti-colorants such as acid salts, hypophosphates, lubricants and mold release agents (such as montanic acid and its metal salts, its esters, its half esters, stearyl alcohols, stearamides and polyethylene waxes), dyes and pigments. Carbon black, crystal nucleating agent, plasticizer, flame retardant (bromine flame retardant, phosphorus flame retardant, red phosphorus, silicone flame retardant, etc.), flame retardant aid, and antistatic agent as agents, conductive agents or colorants. It is possible to further impart desired properties by blending a polymer other than the usual additives such as and thermoplastic resins.

The method of blending these additives is preferably melt-kneading, and a known method can be used for melt-kneading. For example, a liquid crystal polyester resin composition may be obtained by melt-kneading at a temperature of 180 to 350 ° C., more preferably 250 to 320 ° C. using a Banbury mixer, a rubber roll machine, a kneader, a single-screw or twin-screw extruder, or the like. it can. In that case, 1) a batch kneading method with a liquid crystal polyester resin, an optional filler and other additives, and 2) a liquid crystal polyester resin composition containing a high concentration of other additives in the liquid crystal polyester. A method of preparing a product (master pellet) and then adding other thermoplastic resins, fillers and other additives to a specified concentration (master pellet method), 3) liquid crystal polyester resin and other additions. Any method may be used, such as a split addition method in which a portion of the agent is kneaded once and then the remaining filler and other additives are added.

The liquid crystal polyester resin of the present invention and the liquid crystal polyester resin composition containing the same have excellent surface appearance (color tone), mechanical properties, heat resistance, etc. by ordinary molding methods such as injection molding, extrusion molding, and press molding. It can be processed into flame-retardant three-dimensional molded products, sheets, containers, pipes, films and the like. Among them, it is suitable for electrical and electronic parts applications obtained by injection molding.

The liquid crystal polyester resin thus obtained and the liquid crystal polyester resin composition containing the same include, for example, various gears, various cases, sensors, LED lamps, connectors, sockets, resistors, relay cases, switches, coil bobbins, and the like. Condenser, variable condenser case, optical pickup, oscillator, various terminal boards, transformers, plugs, printed wiring boards, tuners, speakers, microphones, headphones, small motors, magnetic head bases, power modules, housings, semiconductors, liquid crystal display parts, Electrical and electronic parts such as FDD carriages, FDD chassis, HDD parts, motor brush holders, parabolic antennas, computer-related parts; VTR parts, TV parts, irons, hair dryers, rice cooker parts, microwave parts, acoustic parts , Audio equipment parts such as audio / laser discs (registered trademarks) / compact discs, lighting parts, refrigerator parts, air conditioner parts, typewriter parts, word processor parts, etc. Phone-related parts, facsimile-related parts, copying machine-related parts, cleaning jigs, oilless bearings, stern bearings, submersible bearings and other various bearings, motor parts, lighters, typewriters and other machine-related parts, microscopes, Optical equipment such as binoculars, cameras, watches, precision machinery related parts; alternator terminal, alternator connector, IC regulator, potential meter base for light dimmer, various valves such as exhaust gas valve, fuel-related, exhaust system, intake system various pipes , Air intake nozzle snorkel, intake manifold, fuel pump, engine cooling water joint, carburetor main body, carburetor spacer, exhaust gas sensor, cooling water sensor, oil temperature sensor, throttle position sensor, crank shaft position sensor, air flow meter, brake Pad wear sensor, thermostat base for air conditioner, motor insulator for air conditioner, separator, heating hot air flow control valve, brush holder for radiator motor, water pump impeller, turbine vane, wiper motor related parts, dustributor, starter switch, Wire harness for starter relay and transmission , Window washer nozzle, air conditioner panel switch board, fuel related electromagnetic valve coil, fuse connector, horn terminal, electrical component insulation plate, step motor rotor, lamp socket, lamp reflector, lamp housing, brake piston, solenoid bobbin, engine oil It can be used for automobile / vehicle-related parts such as filters and ignition device cases. When used as a film, it is used as a magnetic recording medium film, photographic film, condenser film, electrically insulating film, packaging film, drawing film, ribbon film, and as a sheet, it is used for automobile interior ceilings, door trims, and instrument panels. It is useful for pad materials, cushioning materials for bumpers and side frames, sound absorbing pads such as the back of bonnets, seat materials, pillars, fuel tanks, brake hoses, window washer fluid nozzles, air conditioner refrigerant tubes, and their peripheral parts.

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

The manufacturing steps of Examples 1 to 9 and Comparative Examples 1 to 3 were carried out up to 20 times (20 batches), respectively, and the evaluations shown in the following (1) to (5) were performed. When the test was completed with batches less than the maximum number of batches, the average value up to the completed batch was described.

(1) Die head temperature holding time The temperature holding time of the die head was calculated for each test batch by the following formula (3), and the average of 20 batches was calculated.

Equation (3): Die head temperature holding time = (t1 / (t1 + t2))
In the above formula, t1 represents the die head temperature holding time (hr) at the temperature T1 in one cycle of the batch polymerization, and t2 represents the die head temperature holding time (hr) at the temperature T2 in one cycle of the batch polymerization.

(2) Number of batches in which clogging of the base hole of liquid crystal polyester resin occurs (batch)
The operation of the test batch was continued, and the number of batches at which the mouthpiece hole of the discharge port began to be clogged was examined.

(3) Number of black foreign substances in liquid crystal polyester resin pellets (pieces / 15 g)
The measurement was performed using a hot press machine (manufactured by Tester Sangyo). 15 g was collected from the pellets obtained for each test batch, divided into 3 equal parts every 5 g, and the 5 g pellets were pressed at a set temperature of melting point + 10 ° C. to prepare a thin disk-shaped sheet. Similarly, the work of preparing a thin disk-shaped sheet from 5 g of pellets was repeated twice to prepare a total of three sheets. For all three sheets, the number of black foreign substances having a size of 0.2 mm or more was visually counted, and the total value was defined as the number of black foreign substances (pieces / 15 g), and the average value of all the test batches was calculated.

(4) Measurement of melting point (Tm) of liquid crystal polyester resin Observed when liquid crystal polyester resin is measured with a differential scanning calorimeter DSC-7 (manufactured by Perkin Elmer) under a temperature rise condition of 20 ° C./min from room temperature. After observing the heat absorption peak temperature (Tm1), the temperature is kept at the heat absorption peak temperature (Tm1) + 20 ° C. for 5 minutes, then cooled to room temperature under the temperature lowering condition of 20 ° C./min, and then raised again to 20 ° C./min. The heat absorption peak temperature (Tm2) observed when measured under temperature conditions was defined as the melting point (Tm).

(5) Measurement of melt viscosity of liquid crystal polyester resin Using an enhanced flow tester CFT-500D (Orifice 0.5φ x 10 mm) (manufactured by Shimadzu Corporation), the shear rate is 1000 [1] at a temperature of melting point (Tm) + 10 ° C. / Second].

(Example 1)
An acetylation reaction vessel (not shown) equipped with a stirring blade, a distillate tube, a condenser, and a distillate acetic acid container was used.

Further, as shown in FIG. 1, a stirring blade 2, a distillate pipe 4, a distillate acetic acid container (not shown), a decompression device (not shown), a liquid transfer line (not shown) are provided, and a discharge port is provided at the bottom. A polycondensation reaction tank 1 having a volume of 2500 L was used, and a die head 8 to which a discharge valve 7 was connected was attached to the bottom of the polycondensation reaction tank 1, and a mouthpiece hole having a diameter of 5.0 mm was attached to the bottom of the die head 8. A discharge port plate 10 having 40 pieces was attached. The die head 8 has a jacket 9 on the outer wall surface, a liquid heat medium is circulated by a pump, and heating is controlled so that the temperature (T2) after the end of discharge of the die head becomes 325 ° C. A heating type slide plate valve 11 in which a heating wire is embedded is further attached to the discharge port of the die head 8.

Next, in the acetylation reaction tank, 562 parts by mass (54 mol%) of p-hydroxybenzoic acid, 227 parts by mass (16 mol%) of 4,4'-dihydroxybiphenyl, 58 parts by mass (7 mol%) of hydroquinone, and terephthalic acid. 188 parts by mass (15 mol%), 101 parts by mass (8 mol%) of isophthalic acid, 3 parts by mass of hydroquinone as an excess addition of hydroquinone, and 854 parts by mass of anhydrous acetic acid (1.10 equivalents of the total phenolic hydroxyl groups). Was charged and acetylated at 145 ° C. for 1.5 hours with stirring in a nitrogen gas atmosphere.

Next, the distilling pipe was switched to the distilling acetic acid container side, the reaction was continued up to 270 ° C. over 4 hours, and the reaction solution of the acetylation reaction tank was transferred to the polycondensation reaction tank 1 via the liquid transfer line.

Next, the reaction solution in the polycondensation reaction tank 1 was heated to 335 ° C. over 2 hours, decompression was started by a decompression device, the pressure was reduced to 133 Pa (1 torque) over 2 hours, and the mixture was stirred as specified. The polycondensation reaction was terminated when the torque was reached.

Next, the inside of the polycondensation reaction tank 1 is pressurized to 0.25 MPa with nitrogen, the discharge valve 7 of the die head 8 and the slide plate valve 11 are opened, and the polymer is strand-shaped from the discharge port plate 10 via a plurality of mouthpiece holes. And pelletized with a cutter (not shown) while solidifying with cooling water. The time required for discharge was 35 minutes.

In the middle of this polycondensation reaction, the die head temperature is raised from 325 ° C. (T2) to 335 ° C. at the start of discharge of the die head, and the temperature is 335 during t1 (hr) until the end of discharge. The temperature was controlled to be (T1). After the discharge was completed, the die head temperature of 335 ° C. (T1) was cooled to 325 ° C. (T2) and controlled at 325 ° C. (T2) for t2 (hr).

The second batch also undergoes the acetylation reaction and the polycondensation reaction by the above method, and the temperature is raised from 325 ° C. (T2) to 335 ° C. (T1) at the same timing as the first batch during the polycondensation reaction. The temperature was controlled to 335 ° C. (T1) until the end of discharge.

20 batches of polymerization were repeatedly carried out by the above method.

The temperature holding time of the die head at this time (average value of 20 batches) was 0.19.

There was no clogging of the mouthpiece hole at the time of discharge. Regarding the obtained pellets, the number of black foreign substances (average value of 20 batches) was small and there was no problem.

The melting point (average value of 20 batches) of this liquid crystal polyester resin was 311 ° C., and the melt viscosity (average value of 20 batches) was 31 Pa · s.

(Example 2)
A liquid crystal polyester resin was produced in the same manner as in Example 1 except that the temperature (T2) after the end of ejection of the die head was changed to 332 ° C.

There was no clogging of the mouthpiece hole at the time of discharge. Regarding the obtained pellets, the number of black foreign substances (average value of 20 batches) was small and there was no problem.

The melting point (average value of 20 batches) of this liquid crystal polyester resin was 311 ° C., and the melt viscosity (average value of 20 batches) was 31 Pa · s.

(Example 3)
A liquid crystal polyester resin was produced in the same manner as in Example 1 except that the temperature (T2) after the end of ejection of the die head was changed to 311 ° C.

Clogged mouthpiece holes during ejection began to occur at the 14th batch, but 20 batches of polymerization were possible. Regarding the obtained pellets, the number of black foreign substances (average value of 20 batches) was small and there was no problem.

The melting point (average value of 20 batches) of this liquid crystal polyester resin was 311 ° C., and the melt viscosity (average value of 20 batches) was 31 Pa · s.

(Example 4)
A liquid crystal polyester resin was produced in the same manner as in Example 1 except that the temperature (T1) at the start of ejection of the die head was changed to 350 ° C.

Clogged mouthpiece holes at the time of discharge began to occur at the 18th batch, but 20 batches of polymerization were possible. For the obtained pellets, the number of black foreign substances (average value of 20 batches) was a value without any problem.

The melting point (average value of 20 batches) of this liquid crystal polyester resin was 311 ° C., and the melt viscosity (average value of 20 batches) was 31 Pa · s.

(Example 5)
A liquid crystal polyester resin was produced in the same manner as in Example 1 except that the temperature (T1) at the start of ejection of the die head was changed to 328 ° C.

Clogged mouthpiece holes at the time of discharge began to occur in the 16th batch, but 20 batches of polymerization were possible. For the obtained pellets, the number of black foreign substances (average value of 20 batches) was a value without any problem.

The melting point (average value of 20 batches) of this liquid crystal polyester resin was 311 ° C., and the melt viscosity (average value of 20 batches) was 31 Pa · s.

(Example 6)
A liquid crystal polyester resin was produced in the same manner as in Example 1 except that the temperature holding time of the die head was changed to 0.09.

Clogged mouthpiece holes at the time of discharge began to occur at the 17th batch, but 20 batches of polymerization were possible. Regarding the obtained pellets, the number of black foreign substances (average value of 20 batches) was small and there was no problem.

The melting point (average value of 20 batches) of this liquid crystal polyester resin was 311 ° C., and the melt viscosity (average value of 20 batches) was 31 Pa · s.

(Example 7)
A liquid crystal polyester resin was produced in the same manner as in Example 1 except that the temperature holding time of the die head was changed to 0.49.

Clogged mouthpiece holes at the time of discharge began to occur in the 19th batch, but 20 batches of polymerization were possible. For the obtained pellets, the number of black foreign substances (average value of 20 batches) was a value without any problem.

The melting point (average value of 20 batches) of this liquid crystal polyester resin was 311 ° C., and the melt viscosity (average value of 20 batches) was 31 Pa · s.

(Example 8)
As shown in FIG. 3, immediately after the start of discharge, the die head temperature of 335 ° C (T1) is cooled to 333 ° C (T1'), controlled to be 333 ° C (T1') until the end of discharge, and the discharge is completed. After that, the die head temperature of 333 ° C. (T1') was cooled to 323 ° C. (T2'), controlled to be 323 ° C. (T2') until the start of the polycondensation reaction of the next batch, and the polycondensation reaction of the next batch was started. Immediately after, the die head temperature of 323 ° C. (T2') is raised to 325 ° C. (T2) so that the temperature will be 325 ° C. (T2) until the temperature rise to 335 ° C. (T1) at the start of the next discharge. A liquid crystal polyester resin was produced in the same manner as in Example 1 except that it was controlled. At this time, the ratio of the control time of T2'to the control time of T2 was 4.5: 5.5.

There was no clogging of the mouthpiece hole at the time of discharge. For the obtained pellets, the number of black foreign substances (average value of 20 batches) was a value without any problem.

The melting point (average value of 20 batches) of this liquid crystal polyester resin was 311 ° C., and the melt viscosity (average value of 20 batches) was 31 Pa · s.

(Example 9)
As for the polycondensation reaction tank 1 and other devices, the same ones as in Example 1 were used.

The components charged in the acetylation reaction tank were changed to the following, and charged in the reaction vessel.
752 parts by mass (73 mol%) of p-hydroxybenzoic acid
127 parts by mass (9 mol%) of 4,4'-dihydroxybiphenyl
・ 113 parts by mass (9 mol%) of terephthalic acid
・ 131 parts by mass (9 mol%) of polyethylene terephthalate
-Sodium hypophosphate 0.2 parts by mass (0.02% by mass)
771 parts by mass of acetic anhydride (1.11 equivalents of the total phenolic hydroxyl groups)
The acetylation reaction and the polycondensation reaction were carried out in the same manner as in Example 1.

The inside of the polycondensation reaction tank 1 is pressurized to 0.15 MPa with nitrogen for pelletization, the temperature (T2) after the end of discharge of the die head is changed to 340 ° C, and the temperature (T1) at the start of discharge of the die head is 350 ° C. A liquid crystal polyester resin was produced in the same manner as in Example 1 except for the change.

There was no clogging of the mouthpiece hole at the time of discharge. Regarding the obtained pellets, the number of black foreign substances (average value of 20 batches) was small and there was no problem.

The melting point (average value of 20 batches) of this liquid crystal polyester resin was 326 ° C., and the melt viscosity (average value of 20 batches) was 13 Pa · s.

(Comparative Example 1)
A liquid crystal polyester resin was produced in the same manner as in Example 1 except that the temperature of the die head was kept constant at 306 ° C.

Approximately 2 minutes after the start of discharge, the strands began to thin, and 15 minutes later, the polymer became a filamentous polymer, so that discharge was interrupted. After that, an attempt was made to restart the discharge, but the polymer did not come out from the mouthpiece hole, so the test was stopped in one batch.

The melting point of this liquid crystal polyester resin was 311 ° C., and the melt viscosity was 31 Pa · s.

(Comparative Example 2)
A liquid crystal polyester resin was produced in the same manner as in Example 5 except that the temperature (T2) after the end of ejection of the die head was changed to 200 ° C.

There was no clogging of the mouthpiece hole in the first batch discharge, and there was no problem with black foreign matter, but the mouthpiece tended to be clogged from the start of the second batch discharge. After that, as the number of batches increased, the strands became thinner, so the test was stopped after 5 batches. For the obtained pellets, the number of black foreign substances (average value of 5 batches) was large.

The melting point (average value of 5 batches) of this liquid crystal polyester resin was 311 ° C., and the melt viscosity (average value of 5 batches) was 31 Pa · s.

(Comparative Example 3)
A liquid crystal polyester resin was produced in the same manner as in Example 4 except that the temperature (T2) after the end of ejection of the die head was changed to 350 ° C.

Clogged mouthpiece holes during ejection began to occur in the 10th batch, and then the strands became thinner as the number of batches increased, so the test was stopped in 16 batches. The residual polymer in the die head was colored, and the polymer was blown out vigorously at the start of ejection. For the obtained pellets, the number of black foreign substances (average value of 16 batches) was large.

The melting point (average value of 16 batches) of this liquid crystal polyester resin was 311 ° C., and the melt viscosity (average value of 16 batches) was 31 Pa · s.

The method for producing a liquid crystal polyester resin according to the present invention can be widely used for producing a precision component forming material for electrical and electronic applications.

1 Polycondensation reaction tank 2 Stirring blade 3 Distilling pipe 4 Distilling pipe 5 Nitrogen supply line 6, 9 Jacket 7 Discharge valve 8 Die head 10 Discharge port plate 11 Slide plate valve

Claims (3)

A liquid crystal in which a raw material monomer and anhydrous acetic acid are charged into the reaction tank 1 and an acetylation reaction is carried out, and then the reaction solution of the reaction tank 1 is transferred to the reaction tank 2 through a transfer tube connected to the reaction tank 2 to perform deacetation polycondensation. a method of manufacturing a sexual polyester, a liquid crystalline polyester resin obtained raw material melt polycondensation in the reaction vessel 2 was fed into the die head from the reactor 2 through the valve, the discharge port from said die head In the method for producing a liquid crystal polyester resin by a batch type polymerization method in which the resin is discharged so as to form a strand group, the temperature (T1) at the start of discharge of the die head is set to be equal to or higher than the melting point (Tm) of the liquid crystal polyester resin and the melting point (Tm). Tm) + 40 ° C. or less, and while discharging from the die head through the discharge port so as to form a strand group, the temperature of the die head is maintained at the temperature (T1) at the start of discharge, and the next discharge is performed after the discharge of the die head is completed. A method for producing a liquid crystal polyester resin, which keeps the waiting temperature (T2) up to -25 ° C to -3 ° C with respect to the temperature (T1) at the start of ejection of the die head. The first aspect of the present invention, wherein the temperature (T2) on standby from the end of the discharge of the die head to the next discharge is maintained in the range of −5 ° C. to + 25 ° C. with respect to the melting point (Tm) of the liquid crystal polyester resin. A method for producing a liquid crystal polyester resin. The method for producing a liquid crystal polyester resin according to claim 1 or 2, wherein the temperature holding time of the die head satisfies the following formula.
0.05 ≦ (t1 / (t1 + t2)) ≦ 0.5
(In the above formula, t1 represents the die head temperature holding time (hr) at the temperature T1 in one cycle of the batch polymerization, and t2 represents the die head temperature holding time (hr) at the temperature T2 in one cycle of the batch polymerization. )

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