JP3116512B2 - Batch continuous polymerization of liquid crystalline polyester - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a batch type continuous polymerization method for obtaining a high quality liquid crystalline polyester.

[0002]

2. Description of the Related Art In recent years, there has been an increasing demand for higher performance of plastics, and a number of polymers having various new properties have been developed and marketed. Among them, optics characterized by a parallel arrangement of molecular chains. Attention has been paid to anisotropic liquid crystalline polyesters for having excellent fluidity and mechanical properties.

As a method for producing a large amount of liquid crystalline polyester, a batch continuous polymerization method is known. In this method, for example, in the case of a deacetic acid polycondensation reaction, for example, two reaction vessels, a reaction vessel and a polymerization vessel, are allowed to communicate with each other, and the first liquid crystal polyester raw material is mainly acetylated in the reaction vessel. After the reaction, the reaction product is transferred to a polymerization vessel to initiate polymerization. Then, the second liquid crystal polyester raw material is charged into the empty reaction vessel, and a reaction mainly involving acetylation is performed. Next, the first liquid crystal polyester which has been polymerized in the polymerization can is discharged from the discharge port of the polymerization can. When the discharge from the polymerization vessel is completed, the second reaction product in which the reaction mainly including acetylation is completed is transferred from the reaction vessel to the polymerization vessel. Thus, the batch polymerization is continuously performed in an extrusion manner.

[0004]

However, the polymerization in the batch continuous polymerization method is a so-called temperature-rising polymerization in which the reaction is initially performed at a low temperature and gradually at a high temperature. It is necessary to cool the temperature in the can to start the polymerization of the batch. Conventionally, this cooling was naturally cooled, but in many cases, foreign substances were mixed in the liquid crystal polyester obtained by the conventional batch-type continuous polymerization method. An object of the present invention is to provide a batch-type continuous polymerization method for obtaining a high-quality liquid crystalline polyester free of such foreign substances.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to solve the above problems, and as a result, have reached the present invention as follows. That is, the present invention melt-polymerizes a liquid crystalline polyester in a polymerization vessel having a material input port or a liquid transfer port, a polymer discharge port, a stirrer, and a jacket, and discharges the molten polymer. It was charged into the <br/> batch continuous polymerization method repeating the polymerization, after discharging the molten polymer, cooling crystallization temperature of the polymer to the temperature in the reactor of the polymerization reactor within 1.5 hours (Tc) -5 ° C. It is intended to provide a batch-type continuous polymerization method for a liquid crystalline polyester, which is cooled to the following temperature, and then the next raw material is charged.

[0006] In the present invention, the falling temperature crystallization temperature (Tc) refers to an endothermic peak temperature (Dc) observed when a discharged polymer is measured from room temperature under a heating condition of 20 ° C / min in a differential scanning calorimetry (DSC). 20 ° C higher than (Tm) (Tm + 20
(° C.) for 5 minutes, and the exothermic peak temperature observed when measured under a temperature-lowering condition of 20 ° C./min. The batch continuous polymerization in the present invention refers to a polymerization in which polymerization is carried out for a predetermined time in a reaction vessel, a polymer is discharged, the next raw material is transferred to the reaction vessel, and polymerization is started. Say legal.

The number of reaction vessels may be one or more, but at least one vessel (polymerization can) is provided with a raw material inlet or a liquid transfer port, a polymer discharge port, a stirrer, and a jacket. is there. As a process for producing the liquid crystalline polyester, for example, a reaction and polymerization mainly involving acetylation may be carried out in a single vessel in the case of deacetic acid polycondensation reaction, or acetylation may be carried out in a first vessel. The reaction is mainly performed, and the reaction product is transferred to a polymerization vessel through a liquid transfer port,
A method in which polymerization is performed in a polymerization vessel may be used.

It is preferable that the rotating direction of the stirrer is a direction in which the contents are scraped down by the stirring blade. In the scraping direction, the polymer adheres to the upper portion of the stirring blade or the upper portion of the can wall and becomes high in melting point, which is not preferable. The shape of the polymerization vessel and the stirring blade may be any shape as long as it is used for ordinary polyester polymerization, but a helical blade is preferable.

The liquid crystalline polyester obtained by the present invention is a polyester having a melt anisotropy among polyesters comprising units selected from aromatic oxycarboxylate units, aromatic dioxy units, aromatic dicarbonyl units, ethylenedioxy units and the like. And particularly preferably the following structural units (I), (II), (IV) or (I), (II), (III),
It is a liquid crystalline polyester comprising the structural unit of (IV).

[0010]

(Where R ₁ is

And R ₂ represents one or more groups selected from

[0013] One or more groups selected from Also,
In the formula, X represents a hydrogen atom or a chlorine atom, and the structural unit (I
The sum of I) and (III) and the structural unit (IV) are substantially equimolar. ) The structural unit (I) is a structural unit of a polyester formed from p-hydroxybenzoic acid, and the structural unit (II) is 4,4′-dihydroxybiphenyl, 3,3 ′, 5,5′-tetramethyl- 4,4'-
Selected from dihydroxybiphenyl, hydroquinone, t-butylhydroquinone, phenylhydroquinone, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 2,2-bis (4-hydroxyphenyl) propane, and 4,4'-dihydroxydiphenyl ether A structural unit generated from an aromatic dihydroxy compound, a structural unit (III) a structural unit generated from ethylene glycol, a structural unit (IV) a terephthalic acid,
Isophthalic acid, 4,4′-diphenylcarboxylic acid, 2,
Selected from 6-naphthalenedicarboxylic acid, 1,2-bis (phenoxy) ethane-4,4′-dicarboxylic acid, 1,2-bis (2-chlorophenoxy) ethane-4,4′-dicarboxylic acid and diphenyletherdicarboxylic acid The structural units produced from the aromatic dicarboxylic acids obtained are shown below. When the above structural unit (III) is contained, R ₁ is

[0014]

Is at least 70 mol% of the structural unit (II), and R ₂ is Those which occupy at least 70 mol% of the structural unit (IV) are particularly preferred. On the other hand, when the above structural unit (III) is not contained, R ₁ is

[0016]

R ₂ is

Is particularly preferred. The above structural unit (I)
The copolymerization amount of (IV) is optional. However, the following copolymerization amount is preferred from the viewpoint of fluidity.

That is, when the above-mentioned structural unit (III) is contained, the total of the above-mentioned structural units (I) and (II) is calculated from the viewpoint of heat resistance, flame retardancy and mechanical properties.
60 based on the sum of (I), (II) and (III)
-95 mol% is preferable, and 82-93 mol% is more preferable. Further, the structural unit (III) is the structural unit (I),
It is preferably from 40 to 5 mol%, more preferably from 18 to 7 mol% , based on the total of (II) and (III) . Also,
The molar ratio of the structural units (I) and (II) [(I) / (I
I)] is preferably 75/25 to 95/5, more preferably 78/2, from the viewpoint of the balance between heat resistance and fluidity.
2 to 93/7. Further, the structural unit (IV) is structural units
It is substantially equimolar to the sum of positions (II) and (III) .

On the other hand, when the structural unit (III) is not contained, the structural unit (I) is a structural unit from the viewpoint of fluidity.
40 to 90 mol% based on the sum of (I) and (II)
The structural unit (IV) is preferably substantially equimolar to the structural unit (II). When the liquid crystalline polyester of the present invention is polycondensed, the above structural units (I) to (IV)
3,3'-diphenyldicarboxylic acid, aromatic dicarboxylic acids such as 2,2'-diphenyldicarboxylic acid, adipic acid, azelaic acid, sebacic acid,
Aliphatic dicarboxylic acids such as dodecanedioic acid, alicyclic dicarboxylic acids such as hexahydroterephthalic acid, chlorohydroquinone, methylhydroquinone, 4,4'-dihydroxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfide, 4,4 ' Aromatic diols such as dihydroxybenzophenone, 1,4-butanediol, 1,6-hexanediol neopentyl glycol, 1,4-cyclohexanediol, aliphatic and alicyclic diols such as 1,4-cyclohexanedimethanol; Aromatic hydroxycarboxylic acids such as m-hydroxybenzoic acid and 2,6-hydroxynaphthoic acid and p-aminophenol, p-aminobenzoic acid and the like are further copolymerized in a small proportion that does not impair the object of the present invention. I can do it.

The method of producing the liquid crystalline polyester in the present invention is not particularly limited, and can be produced according to a known melt polycondensation method of the liquid crystalline polyester. However, when the above structural unit (III) is not contained, the following method is used. When (1), (2) or structural unit (III) is included, the following production method (3) is preferably mentioned. (1) A method of producing from a diacylated product of an aromatic dihydroxy compound such as p-acetoxybenzoic acid and 4,4'-diacetoxybiphenyl and an aromatic dicarboxylic acid such as terephthalic acid by a deacetic acid polycondensation reaction.

(2) p-hydroxybenzoic acid and 4,
A method of reacting an aromatic dihydroxy compound such as 4'-dihydroxybiphenyl or an aromatic dicarboxylic acid such as terephthalic acid with acetic anhydride to acylate a phenolic hydroxyl group, followed by a deacetic acid polycondensation reaction. (3) In the presence of a polyester polymer, oligomer or bis (β-hydroxyethyl) ester of an aromatic dicarboxylic acid such as bis (β-hydroxyethyl) terephthalate from ethylene glycol and an aromatic dicarboxylic acid such as terephthalic acid (1) or A method of manufacturing according to the method of (2).

After discharging the thus obtained liquid crystalline polyester, the temperature of the jacket of the polymerization vessel is cooled to a temperature lower than the crystallization temperature (Tc) -5 ° C. of the polymer within 1.5 hours, preferably within 1 hour. Is important (Tc−
10 ° C.) or lower, more preferably (Tc−15 ° C.) or lower. Higher than (Tc-5 ℃) or (Tc-5 ℃)
Even if it is below, if left for more than 1.5 hours, the remaining polymer in the can will have a high melting point, and the high-melting substance will be mixed as foreign matter into the polymerized polymer of the next batch and clog the nozzle of the discharge port. Or the physical properties of the molded article become poor.

The liquid crystalline polyester used in the present invention
(A) indicates that many of them can measure the logarithmic viscosity in pentafluorophenol, in which case 0.1
It is preferably 0.5 or more when measured at 60 ° C. at a concentration of g / dl, particularly 1.0 to 3.0 dl when the above structural unit (III) is contained.
/ G is preferable, and when the above structural unit (III) is not contained,
2.0 to 10.0 dl / g is preferred.

The melt viscosity of the liquid crystalline polyester (A) used in the present invention is preferably from 10 to 20,000 poise, more preferably from 20 to 10,000 poise. The melt viscosity was determined at a melting point (Tm) of + 10 ° C. and a shear rate of 1,000 (1/1).
(Seconds) under the condition of a Koka flow tester.

[0026]

The present invention will be further described with reference to the following examples. Example 1 vertical and horizontal ratio for the reaction can and polycondensation in which a stirring shaft fitted with a scraping-down direction of the helical ribbon blade into the polymerization apparatus having an inner volume of 0.1 m ³ of 2.5 to a height of 0.035 m ³ The polymerization was carried out as follows using a polymerization can.

In a reaction vessel, 22.1 kg of p-hydroxybenzoic acid,
2.8 kg of 4,4'-dihydroxybiphenyl, 4.8 kg of polyethylene terephthalate, 2.5 kg of terephthalic acid and 21.7 kg of acetic anhydride were charged, and reacted at 130 to 250 ° C. for 5 hours. Thereafter, the reaction product was transferred to a polymerization vessel. And at 250-330 ℃ 2
After the reaction for 2 hours, the pressure in the polymerization vessel was reduced to 1.0 Torr over 2 hours, and stirring was continued for 1 hour to complete the polycondensation reaction. Then, after pressurizing the inside of the polymerization can to 4 kg / cm ² , the polymer was discharged in the form of a strand via a die. The obtained liquid crystalline polyester
The theoretical structural formula of (A) is as follows.

[0028]

This liquid crystalline polyester (A) was converted from room temperature to 20 ° C./200° C. using a DSC-7 model manufactured by PerkinElmer.
The melting point (Tm) was measured at a speed of
° C.

Next, this polymer was kept at Tm + 20 ° C., that is, 336 ° C. for 5 minutes, and then cooled at a rate of 20 ° C./min, and the crystallization temperature (Tc) was measured to be 269 ° C. After the polymer discharge is completed, pour water into the jacket of the polymerization can,
The temperature in the vessel was cooled to 250 ° C. over 50 minutes, and the reaction product of the next batch immediately reacted under the same conditions in the reaction vessel was transferred to a polymerization vessel and polymerized under the same conditions. After the polymerization, the mixture was discharged to obtain a liquid crystalline polyester (B). Table 1 shows the pelletizing yield and thermal characteristics of these liquid crystalline polyesters.

[0031]

Examples 2 to 5 and Comparative Examples 1 to 3 The reaction was carried out under the same conditions as in Example 1 using a reaction vessel and a polymerization vessel.
Discharging of liquid crystalline polyester (A) with the characteristics shown in Table 1
Then, a predetermined time (t) until the temperature (T) shown in Table 2 ₁) Cold
After the cooling, at that temperature for a predetermined time (t_Two) After holding,
The reactants of the second batch reacted in the reaction vessel are transferred to the polymerization vessel.
Liquor, polymerize and discharge at T-330 ° C. as described in Example 1,
Pellets were obtained to obtain a liquid crystalline polyester (C). these
Pelletization yield and thermal properties of liquid crystalline polyester (C)
It is shown in Table 2.

[0033]

When t ₁ is longer than 1 hour (Comparative Example 1,
2) When T is higher than (Tc-5 ° C.) (Comparative Example 3), the melting point rises as shown in Table 2, and when the liquid crystalline polyester (C) is discharged, the high melting point polymer causes clogging, It can be seen that the pelletization yield decreases.

[0035]

According to the present invention, after the polymerized molten polymer is discharged, the temperature in the polymerization can is cooled within 1.5 hours to a temperature lower than the crystallization temperature (Tc) of the polymer −5 ° C. After that, since the next raw material is added, the melting point of the remaining polymer is prevented from being increased, and as a result, there is no contamination of foreign matters, and the pelletization yield is improved.

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-56-104932 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) C08G 63/78-63/87

Claims (1)

(57) [Claims] 1. A liquid crystal polyester is melt-polymerized in a polymerization vessel having a material input port or a liquid transfer port, a polymer discharge port, a stirrer, and a jacket, and a molten polymer is discharged. In a batch-type continuous polymerization method in which the polymerization is repeated by charging the molten polymer, the molten polymer is discharged,
Within 1.5 hours, the inside temperature of the polymerization can is cooled to a temperature lower than the temperature drop crystallization temperature (Tc) -5 ° C. of the polymer,
A batch type continuous polymerization method for liquid crystalline polyester characterized by charging the next raw material.