JPH0533257B2 - - Google Patents

Description

[Detailed description of the invention]

<Technical Field> The present invention relates to an improvement in a method for producing a polyester whose main raw materials are terephthalic acid and/or its ester-forming derivative and ethylene glycol. More specifically, the present invention relates to a method for producing a polyester containing a large amount of fine particles and having excellent moldability such as thread-spinning and film-forming properties, as well as slipperiness and surface properties of molded products. <Prior art and its problems> Saturated linear polyester, especially polyethylene terephthalate, has excellent mechanical properties, heat resistance, weather resistance, electrical insulation resistance, and chemical resistance, so it is widely used in textiles, films, and other fields such as clothing and industrial applications. , widely used in the form of blow molding and other molded products. When polyester is used in these forms, fine particle-containing polyester compositions are required due to their value as final products such as passability in molding and post-processing processes, opacity for clothing, and slipperiness of film products. It is usually done to make the polymer flow easier during molding, and also to make the molded product opaque or to give the molded product surface smoothness by giving it an appropriate amount of unevenness. It is. As such fine particles, it has been proposed that fine particles (internal particles) are precipitated during the production of polyester using residues of metal compounds used as catalysts or additives during the production of polyester. Although this method has the drawback that the amount and diameter of precipitated particles easily change due to slight variations in manufacturing conditions, it improves the affinity of the particles produced with the polymer, and also improves the ability to classify and crush the particles. It has the advantage of not requiring complicated operations, and if the above-mentioned drawbacks such as the generation of agglomerated particles and coarse particles can be overcome, its utility value is great. Efforts have been made for a long time to make use of the advantages of the method of precipitating fine particles using such metal compound residues and to improve the disadvantages.
-13234 Publication, Special Publication No. 52-32914, Special Publication Sho
53-4103, JP 53-36877, JP 54-44040, JP 50-144798, JP 51-112860, etc. disclose methods using lithium compounds and phosphorus compounds. is disclosed.
By the way, polyethylene terephthalate usually contains bis-(β-hydroxyethyl) terephthalate and/or its low polymer (hereinafter referred to as BHT).
The first step is to produce BHT, and the second step is to polymerize BHT at high temperature and under reduced pressure. However, BHT is manufactured industrially by transesterification reaction between lower alkyl ester of terephthalic acid and ethylene glycol or through esterification reaction between terephthalic acid and ethylene glycol, but it is generally difficult to maintain the reaction rate constant. It is. Furthermore, even in the second step of polymerizing BHT under high temperature and reduced pressure, it is generally difficult to keep the reaction conditions constant, and even when producing polymers with the same degree of polymerization, it is difficult to keep the reaction time etc. constant. It is. On the other hand, in the method of precipitating fine particles during polyester production using the residue of a metal compound, the reaction rate of BHT, polycondensation reaction time, and polycondensation reaction conditions are It has the disadvantage that the amount and diameter of particles produced tend to fluctuate depending on various conditions such as. In order to solve this time-consuming problem, a method of adding lithium compounds and/or calcium compounds by specifying the timing and order of addition is proposed, for example, in Japanese Patent Application Laid-open No.
No. 53-25694, No. 54-90397, No. 55-
Publication No. 131015, Publication No. 56-127626 and Publication No. 58-
This is proposed in publications such as Publication No. 225124. However, even with such a method, it is still difficult to make the particles produced fine and uniform, to suppress the production of agglomerated coarse particles, and to make the diameter and amount of the produced particles uniform. Furthermore, JP-A-54-113696 proposes a method in which ethylene glycol is added to BHT after the esterification reaction, and then a lithium compound and a phosphorus compound are added for polycondensation. It is not possible to suppress the fluctuation of
It was found that this method has serious drawbacks such as problems such as solidification of BHT. The present inventors have conducted intensive studies to solve the drawbacks of the method of precipitating fine particles in a polymer using the residues of the metal compounds described above, and as a result, the inventors have determined that the metal compounds and phosphorus compounds are added by a specific method, and If a specific amount of ethylene glycol is added at a specific time to perform a polycondensation reaction, the BHT reaction rate will fluctuate,
The particle amount and particle size can be stabilized even when the polycondensation reaction conditions fluctuate, and even BHT
The present invention has been achieved based on the discovery that problems such as solidification can be solved. <Objective of the Invention> That is, the object of the present invention is to perform a transesterification or esterification reaction between terephthalic acid and/or its ester-formable derivative and ethylene glycol, and then polycondensate it to form a polymer based on the metal compound residue. It is an object of the present invention to provide a method for producing polyester that can produce fine particles stably and with good reproducibility even under fluctuations in production conditions. Another object is to provide a method for producing polyester that suppresses the production of aggregated particles and coarse particles and produces fine and uniform particles with good reproducibility. <Configuration of the Invention> The object of the present invention described above is to provide terephthalic acid and/or
Or when producing a polyester whose main constituent unit is ethylene terephthalate from its polyester-forming derivative and ethylene glycol,
After substantially completing the transesterification or esterification reaction between terephthalic acid and/or its polyester-forming derivative and ethylene glycol, an alkali metal compound is added, and ethylene terephthalate is added simultaneously with or after the addition of the alkali metal compound. A method for producing polyester, which comprises adding 0.1 to 0.8 times mole of ethylene glycol to the components, then adding a phosphorus compound and an alkaline earth metal compound to a reaction system at 180 to 270°C, and then polycondensing the mixture. It can be achieved by doing so. In the method of the present invention, terephthalic acid and/or
Alternatively, BHT is produced from a derivative thereof capable of forming an ester and ethylene glycol. Derivatives of terephthalic acid capable of forming esters include lower alkyl esters of terephthalic acid, acid anhydrides, etc., but dimethyl terephthalate and diethyl terephthalate are preferred. A lower alkyl ester of terephthalic acid and ethylene glycol are transesterified in the presence of a conventional transesterification catalyst, such as an alkali metal compound, an alkaline earth metal compound, a manganese compound, a zinc compound, etc. BHT is produced by performing a direct esterification reaction under pressure or normal pressure. Of course, the BHT referred to in the present invention includes acid components such as isophthalic acid, adipic acid, 2,6-naphthalenedicarboxylic acid, 5-sodium sulfoisophthalic acid, tetramethylene glycol, neopentyl glycol, 1,4- Glycol components such as cyclohexanedimethanol and polyalkylene glycol may also be contained. The BHT used in the present invention preferably has a reaction rate of 90
% or more, more preferably 94% or more, still more preferably 96% or more. If the reaction rate is less than 90%, the particles produced will aggregate and become coarse, and the amount of particles will become unstable, which is not preferable. In the present invention, an alkali metal compound is added after the transesterification reaction and/or esterification reaction is substantially completed, and 0.1 Add ~0.8 times molar ethylene glycol. Examples of the alkali metal compound used include alkali metal hydrides, hydroxides, organic carboxylates, halides, glycolates, and alcoholates, but the compound must be soluble in ethylene glycol. Specifically, lithium acetate, sodium propionate, lithium chloride, lithium hydride, lithium hydroxide, caustic potash, etc. can be mentioned, and among them, lithium compounds such as lithium acetate and lithium hydroxide are particularly preferred, and two or more of them are preferably used. They can also be used together. The amount of the alkali metal compound used is preferably 1 to 100 equivalents, more preferably 5 to 50 equivalents, even more preferably 10 to 40 equivalents, per 10 ⁶ g of polymer obtained. Polymers that provide the amount of alkali metal compounds used
If the amount is less than 1 equivalent per 10 ⁶ g, the amount of particles produced will be insufficient, and the amount of particles produced will fluctuate as the BHT reaction rate fluctuates, or coarse particles or agglomerated particles will be produced, which is not preferable. Moreover, if the amount of the alkali metal compound used is more than 100 equivalents, coarse particles and aggregated particles will be generated in the obtained polymer, and the color tone of the obtained polymer will deteriorate, which is not preferable. A feature of the present invention is that ethylene glycol is added in an amount of 0.1 to 0.8 times the mole of terephthalic acid and/or its polyester-forming derivative simultaneously with or after adding the alkali metal compound. The amount of ethylene glycol added is more preferably 0.2 to 0.7 times the mole, and more preferably 0.3 times the amount.
~0.6 times molar. If the amount of ethylene glycol added is less than 0.1 times the mole, the particle size produced may become uneven due to changes in polymerization conditions, or the amount of particles produced may not be constant, and if the amount added is more than 0.8 times the mole, aggregated particles may occur. This is undesirable because problems such as formation of BHT, lowering of the softening point of the resulting polymer, and solidification of BHT occur. Ethylene glycol must be added at the same time as the alkali metal compound or after the alkali metal compound is added; if ethylene glycol is added before the alkali metal compound is added, BHT may solidify or form. The effect of stabilizing the particle size and particle amount of the particles is not observed, and rather, it is undesirable that agglomerated particles are formed and the softening point is lowered. Ethylene glycol may be added as a medium for slurry or solution of each compound to be added, but even in this case, ethylene glycol must be added in the amount necessary to obtain the desired effect of the present invention. It is also possible to further add a part or all of the amount independently, simultaneously with or after the addition of the alkali metal compound. Another feature of the invention is that after adding the alkali metal compound and ethylene glycol
It consists in adding phosphorus compounds and alkaline earth metal compounds at 270°C. The temperature when adding phosphorus compounds and alkaline earth metal compounds is 180-270℃.
The temperature is preferably 190 to 250°C, more preferably 200 to 240°C. If the temperature is lower than 180℃, the particles produced will aggregate or the amount of particles will become unstable.If the temperature is higher than 270℃, the particles will aggregate or the amount of particles will become unstable, and furthermore, the softening point will decrease, the polymer will become colored, etc. Problems arise and are not desirable. As the phosphorus compound used in the present invention, one or more phosphorus compounds selected from phosphoric acid, phosphorous acid, phosphonic acid, and lower alkyl esters and phenyl esters of these phosphoric acids can be used. Specifically, phosphoric acid, trimethyl phosphate, triethyl phosphate, triphenyl phosphate, acidic phosphoric acid, acidic phosphoric acid, phosphoric acid esters such as methyl ester, phosphorous acid, trimethyl phosphite, triethyl phosphite, etc. Phosphite, methylphosphonic acid, phenylphosphonic acid, benzylphosphonic acid and methylphosphonic acid methyl ester,
Examples include phosphonic acid esters such as phenylphosphonic acid ethyl ester and benzylphosphonic acid phenyl ester. The amount of phosphorus compound used is the amount of polymer obtained 10 ⁶
The total amount of phosphorus element per g is preferably 2-
30 equivalents, more preferably 3 to 25 equivalents, still more preferably 5 to 20 equivalents. The amount of phosphorus compound used gives the polymer 10 ⁶
If the total amount of phosphorus element per gram is less than 2 equivalents, it will not be possible to suppress the generation of coarse particles and agglomerated particles, and the amount of particles generated will not be stabilized against fluctuations in the BHT reaction rate. The heat resistance of the polymer decreases and the resulting polymer becomes colored. Furthermore, if the amount is more than 30 equivalents, the generation of coarse particles and agglomerated particles cannot be suppressed, and furthermore,
This is undesirable because it reduces the physical properties of the obtained polymer, such as by-producing diethylene glycol and lowering the softening point. Further, the alkaline earth metal compound used in the present invention is soluble in ethylene glycol, and examples thereof include organic carboxylates and glycolates of alkaline earth metal compounds. Specifically, calcium acetate, barium propionate,
Examples include strontium butyrate and calcium ethylene glycolate, and two or more of these may be used in combination. Preferably calcium acetate,
Calcium compounds such as calcium ethylene glycolate are used. The amount of alkaline earth metal compound used is preferably 1 to 50 equivalents, more preferably 2 to 30 equivalents, and even more preferably 3 to 20 equivalents, per 10 ⁶ g of the resulting polymer. When the amount of alkaline earth metal compound used is less than 1 equivalent per 10 ⁶ g of polymer obtained,
If the amount of particles produced is insufficient or exceeds 50 equivalents, the production of coarse particles and agglomerated particles cannot be avoided, and the amount of particles produced fluctuates as the BHT reaction rate fluctuates, making it difficult to maintain stable quality. Can't get polymer. In the method of the invention, after adding the alkali metal compound and ethylene glycol, the phosphorus compound and the alkaline earth metal compound are added. The addition interval of ethylene glycol, phosphorus compound and alkaline earth metal compound is preferably 1 to 30 minutes.
minutes, more preferably 3 to 20 minutes. If the addition interval is less than 1 minute, coarse particles and agglomerated particles will be generated, which is not preferable. Further, if the addition interval is longer than 30 minutes, it is not preferable because diethylene glycol is produced as a by-product and the softening point of the resulting polymer decreases. Further, the interval between additions of the phosphorus compound and the alkaline earth metal compound is preferably 1 to 30 minutes, more preferably 3 to 20 minutes. If the addition interval is less than 1 minute, coarse particles and agglomerated particles are likely to occur, and
This is undesirable because the amount of particles produced varies due to variation in the BHT reaction rate. If the addition interval is longer than 30 minutes, coarse particles and agglomerated particles are likely to be generated, and the resulting polymer tends to be colored or have a lower softening point, which is undesirable. The phosphorus compound and the alkaline earth metal compound may be added first or at the same time, but it is more preferable to add the alkaline earth metal compound first because the particles are made finer. After adding the metal compound, phosphorus compound and ethylene glycol, a polycondensation reaction is carried out in the presence of a conventional polycondensation reaction catalyst. Suitable polycondensation reaction catalysts include antimony trioxide and germanium dioxide, but other catalysts such as tetraethyl titanate and antimony glycolate may also be used. <Effects of the Invention> According to the method of the present invention, terephthalic acid and/or
Or, a derivative capable of forming a polyester is subjected to transesterification or esterification reaction with ethylene glycol, and then polycondensed to produce fine particles based on the residue of the metal compound in the polymer, which can be stably reproduced even under fluctuations in manufacturing conditions. This makes it possible to produce particles with high efficiency, and it is possible to uniformly refine the particles to be produced. The polymer obtained by the method of the present invention has excellent particle dispersibility and can be obtained with good reproducibility, so when formed into molded products such as fibers and films, the following effects are exhibited. (1) There is less clogging of the polymer filter during the silk-spinning and film-forming process, and an increase in filtration pressure can be suppressed. (2) Coarse particles and coarse protrusions due to coarse particles are reduced, resulting in fine irregularities on the surface of threads and films.
Improved uniformity. (3) Since the reproducibility of particles in the polymer is good, molded products such as threads and films can be produced with good reproducibility. The present invention will be explained in more detail with reference to Examples below. Note that parts in the examples are parts by weight, and the measurement methods for each characteristic are as follows. [Polymer color tone] Measured in chip form using a direct-reading color difference meter (Suga Test Instruments Co., Ltd.), and expressed as b value (Hunter value). [Intrinsic viscosity] Measured at 25°C using O-chlorophenol as a solvent. [Solution haze] 2.7 g of polymer was dissolved in 20 ml of a mixed solvent of phenol/tetrachloroethane (6/4 weight ratio), and ASTM-D was measured using an integrating sphere type HTR Meter SEP-H type haze meter manufactured by Nippon Seimitsu Kogaku Co., Ltd. -100362, measure the solution haze and use it as a guide to the amount of particles in the polymer. [Dispersion state of particles] 10 mg of chips was sandwiched between two cover glasses.
Prepare preparations by melt pressing at 280℃,
Observation was made under a dark field polarizing microscope and evaluation was made based on the following criteria. Particle size Classification state A 0.5 to 1.5μ 1st grade No coarse particles of 10μ or more B 1.5 to 3.0μ 2nd grade 10μ to 20μ coarse particles present C 3.0μ or more 3rd grade Coarse particles of 20μ or more present Example 1 100 parts of dimethyl terephthalate, 55 parts of ethylene glycol and 0.04 part of manganese acetate tetrahydrate are placed in a reaction vessel equipped with a rectification column and a stirring device, and the temperature is gradually raised from 140°C to 230°C over 4 hours while stirring, and distillation is carried out. The transesterification reaction is carried out while methanol is taken out of the system, and the reaction rate is
Got 99% BHT. The obtained BHT was transferred to a polymerization reactor, 0.3 parts of lithium acetate was dissolved in 3 parts of ethylene glycol, and then ethylene glycol was added.
10 parts were added (0.41 times the total amount by mole). reaction system
Hold at 220℃ to 230℃ for 5 minutes, then remove calcium acetate.
0.15 parts and 0.03 parts of antimony trioxide were added along with 3 parts of ethylene glycol, and after 5 minutes 0.25 parts of trimethyl phosphate was added along with 3 parts of ethylene glycol. After adding trimethyl phosphate 5
After 60 minutes have elapsed, start reducing the pressure and increasing the temperature, and reduce the degree of vacuum to 1 mmHg or less in 60 minutes.
The time at which mmHg was reached is called the decompression rate), and the temperature was raised to 290°C, and polycondensation was carried out under these conditions for 3 hours to obtain a polymer with an inherent clay of 0.650. The quality of the polymer is b value +4.0, softening point 261.0℃, solution haze 43%, and the particles in the chip are uniform particles of approximately 0.8μ.
No aggregated particles or coarse particles with a size of 10μ or more were observed. Example 2 A polymer was produced in exactly the same manner as in Example 1, except that the decompression rate was changed to 50 minutes and 70 minutes, and polycondensation was performed until the same viscosity as in Example 1 was obtained. The polymer quality is as shown in Table 1, and the polymer quality does not change even if the pressure reduction rate and polymerization time change. Comparative Example 1 Exactly the same as Example 2 except that lithium acetate, trimethyl phosphate, and calcium acetate and antimony trioxide were each added together with 3 parts of ethylene glycol, and ethylene glycol alone was not added. The polymer was produced using The polymer quality is as shown in Table 1, and it can be seen that the amount of particles produced and the dispersion state of the particles change as the pressure reduction rate and polymerization time change. Example 3 A transesterification reaction was carried out in the same manner as in Example 1 to obtain BHT with a reaction rate of 95% and 98%. A metal compound and a phosphorus compound were added to the obtained BHT and a polycondensation reaction was performed in the same manner as in Example 1. The quality of the obtained polymer is as shown in Table 2, and even if the reaction rate varied, the quality hardly changed. Comparative Example 2 A polycondensation reaction was carried out in the same manner as in Example 3, except that the amount of ethylene glycol added and the temperature at the time of addition of the phosphorus compound and the alkaline earth metal compound were changed to obtain a polymer. The quality of the obtained polymer is shown in Table 2, and it can be seen that the particle characteristics change greatly as the reaction rate changes. Example 4 and Comparative Example 3 105.5 parts of BHT consisting of terephthalic acid and ethylene glycol with a reaction rate of 98% and a molar ratio of ethylene glycol component/terephthalic acid component = 1.2 was added to a reactor.
It was stored at 240°C, and a slurry of 86.5 parts of terephthalic acid and 38.8 parts of ethylene glycol (molar ratio 1.2) was continuously fed at a constant rate over 4 hours at normal pressure. The reaction temperature was controlled at 230-245°C during slurry supply, and at 240-250°C after completion of slurry supply to carry out the esterification reaction. 105.5 parts of the produced BHT was transferred to a polymerization reactor, and a metal compound, a phosphorus compound, and ethylene glycol were added in the same manner as in Example 1 and Comparative Example 2. Table 3 shows the pressure reduction rate and manufacturing conditions. Thereafter, a polycondensation reaction was carried out to obtain the polymers shown in Table 3. Table 3 shows that the method of the present invention can stably produce a polymer free of coarse particles and agglomerated particles even when the BHT reaction rate and polymerization conditions vary, whereas the methods other than the present invention produce coarse particles and agglomerated particles. It can be seen that it becomes unstable due to changes in conditions. Comparative Example 4 105.5 parts of BHT (reaction rate 98%) produced in the same manner as in Example 4 was transferred to a polymerization reactor, and 12.8 parts of ethylene glycol (0.400 times the mole relative to the terephthalic acid component) was added at 240°C. As a result, the surface of BHT solidified. Example 1 except that 10 parts of ethylene glycol was not added because it dissolved after 1 hour.
The same amounts of lithium acetate, calcium acetate, trimethyl phosphate, and antimony trioxide were simultaneously added to carry out polycondensation. The quality of the polymer obtained after 3 hours was: intrinsic viscosity 0.640, b value + 3.0, softening point
260.1℃, solution haze 62%, and particles in the polymer
It was non-uniform with a thickness of about 0.5μ to 3μ. In addition, aggregated particles and coarse particles of 20μ or more were scattered throughout the polymer. Example 5 100 parts of dimethyl terephthalate, 55 parts of ethylene glycol, and 0.09 parts of magnesium acetate were charged, and a transesterification reaction was carried out to achieve a reaction rate of 99%.
Got BHT. The obtained BHT was transferred to a polymerization reactor, and 0.4 parts of lithium acetate was added with 4 parts of ethylene glycol.
of ethylene glycol and then add ethylene glycol
10 parts were added. The reaction system was held at 210-220°C for 5 minutes, and 0.1 part of calcium acetate and 0.03 part of antimony trioxide were added together with ethylene glycol. After 5 minutes, 0.3 part of trimethyl phosphate and 0.01 part of phosphorous acid dissolved in 4 parts of ethylene glycol were added, and after another 5 minutes, the pressure was reduced and the temperature was increased at a rate of 60 minutes, and polycondensation was carried out for 3 hours. A polymer with an intrinsic viscosity of 0.635, a softening point of 260.1°C, and a solution haze of 53% was obtained. The particles in the polymer were uniform with a size of about 0.7μ, and no coarse particles or agglomerated particles with a size of 10μ or more were observed. Further, when the polycondensation reaction was carried out at a decompression rate of 90 minutes, a polymer having an intrinsic viscosity of 0.630 and a solution haze of 53% was obtained after 3 hours and 20 minutes. The particles in the polymer were uniform with a size of about 0.7μ, and no coarse particles or agglomerated particles with a size of 10μ or more were observed.

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Claims (1)

[Claims] 1 When producing a polyester whose main constituent unit is ethylene terephthalate from terephthalic acid and/or its polyester-forming derivative and ethylene glycol, terephthalic acid and/or its polyester-forming derivative and ethylene glycol are used.
Further, after substantially completing the transesterification reaction or esterification reaction between the polyester-forming derivative and ethylene glycol, an alkali metal compound is added, and 0.1 1. A method for producing polyester, which comprises adding ethylene glycol in an amount of up to 0.8 times the mole, then adding a phosphorus compound and an alkaline earth metal compound to a reaction system at 180 to 270°C, followed by polycondensation.