JP2016160313A - Manufacturing method of polyester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method capable of continuously producing a polymer having good quality when recycling a recycle polyester dust as a manufacturing raw material of polyester.SOLUTION: There is provided a method for manufacturing polyester by adding a recycle polyester dust with percentage of 5 to 8 mass% to a polyester low polymer of a reaction temperature of 255 to 260°C when conducting an esterification reaction with terephthalic acid and a derivative thereof and ethylene glycol as raw materials, further supplying an alkali compound to the polyester dust of 30 to 120 ppm and continuously poly-condensing the resulting polyester low polymer.SELECTED DRAWING: None

Description

  The present invention relates to a method for continuously producing polyester. More specifically, the present invention relates to a method for producing a polyester in which polyester waste is added to a polyester low polymer and the quality of the polyester is stabilized using an alkali compound.

  Conventionally, as for polyethylene terephthalate (hereinafter sometimes abbreviated as PET), first, terephthalic acid (hereinafter sometimes abbreviated as TPA) and ethylene glycol (hereinafter sometimes abbreviated as EG) are esterification reactors. The polyester low polymer thus produced is sent to a polycondensation reaction apparatus and then subjected to a polycondensation reaction. The PET thus obtained is widely used as clothing fibers, industrial material fibers, films, bottles, plastics, and the like due to its excellent properties.

  Polyester waste such as fiber, film, and resin generated in these manufacturing processes is usually disposed of after use, but when these polyester waste is burned, high heat is generated and the incinerator is damaged. There is a problem that the life of the incinerator is shortened greatly.

  Moreover, when not burning polyester waste, since polyester waste does not rot and decompose, it will remain semipermanently and it is also a problem from an environmental viewpoint. For this reason, effective use of polyester waste is industrially extremely important in terms of cost and the like.

Under such circumstances, as a method for using polyester waste, for example, when depolymerizing polyester waste, bishydroxyethyl terephthalate having an equivalent ratio of glycol component to acid component of 1.3 to 2.0 and / or its equivalent The low polymer is present in the reaction vessel in a molten state, EG and polyester waste are added simultaneously and continuously, and the esterification reactor is stirred at 215 to 250 ° C. with an equivalent ratio of glycol component to acid component of 1 A method of supplying a part of the reaction product to the polymerization reaction system after depolymerization while maintaining at .3 to 2.0 has been proposed (see Patent Document 1).
However, since some moisture is contained in the polyester scrap, the moisture is accumulated in the reaction system as the depolymerization proceeds, and there is a problem that the depolymerization reaction is suppressed. In addition, a method has been proposed in which polyester waste is supplied during an ester reaction or a polycondensation reaction using a melt extruder to obtain a polyester polymer (see Patent Document 2). Since the polyester scrap charging device is complicated, there is a problem that it is not preferable economically.

Japanese Patent Publication No. 60-248646 JP 2002-249557 A

  Accordingly, an object of the present invention is to solve the above-mentioned problems and to provide a method for producing polyester capable of stabilizing polymer quality by effectively utilizing recycled polyester waste in a method for continuously producing polyester.

  The inventors of the present invention have arrived at the present invention as a result of studies to solve the above problems.

  The polyester production method of the present invention is a method of continuously producing a polyester by subjecting terephthalic acid and / or its derivative and ethylene glycol to an esterification reaction and subjecting the resulting polyester low polymer to a polycondensation reaction. In which a recycled polyester waste is added at a ratio of 5 to 8% by mass to a polyester low polymer in an esterification reaction apparatus having a reaction temperature of 255 to 260 ° C., and an alkali compound is further supplied in an amount of 30 to 120 ppm. It is a manufacturing method.

  According to a preferred embodiment of the polyester production method of the present invention, the alkali compound is an alkali compound selected from the group consisting of tetraethylammonium hydroxide, potassium hydroxide and sodium hydroxide.

  According to the preferable aspect of the manufacturing method of the polyester of this invention, the said polyester waste is the recycled polyester waste generated in the manufacturing process of a fiber or a polyester product.

  According to a preferred embodiment of the polyester production method of the present invention, the glycol component used in the esterification reaction is at least one selected from the group consisting of ethylene glycol and 1,4 butanediol.

  According to the present invention, polyester waste can be reused as a raw material for producing continuously produced polyester, and by adding an alkali compound, the resulting polymer has good polymer quality and can maintain stable quality. Can be manufactured.

FIG. 1 is a side view showing a flowchart for illustrating the method for producing a polyester of the present invention.

  The polyester production method of the present invention is a method for continuously producing a polyester by performing an esterification reaction using terephthalic acid and / or a derivative thereof and ethylene glycol as raw materials, and subjecting the obtained polyester low polymer to a polycondensation reaction. Is a method for producing a polyester in which recycled polyester waste is added to a polyester low polymer in an esterification reaction apparatus and an alkali compound is further supplied.

  The alkali compound used in the present invention may be any alkali compound that promotes the transesterification reaction, and examples thereof include alkali metal hydroxides. Specifically, sodium hydroxide, calcium hydroxide, tetraethylammonium hydroxide, and the like can be used.

  In this invention, it is important that the addition amount of an alkali compound is 30-120 ppm with respect to 5-8 mass% of polyester waste to add. The addition amount of the alkali compound is preferably 40 to 100 ppm, more preferably 40 to 50 ppm. By making the addition amount of the alkali compound as described above, it is possible to suppress the acid component generated when the recycled waste is dissolved.

  The polyester produced in the present invention is a polyester mainly composed of ethylene terephthalate, and specifically, for example, a polyester composed of terephthalic acid or a lower alkyl ester thereof and EG. Part of the terephthalic acid component is mixed with aromatic dicarboxylic acids such as isophthalic acid, naphthalenedicarboxylic acid and diphenoxyethanedicarboxylic acid, and aliphatic carboxylic acids such as dodecanedioic acid, adipic acid, sebacic acid, azelaic acid and decanedicarboxylic acid. It can be replaced with an acid, or an alicyclic dicarboxylic acid such as cyclohexanedicarboxylic acid, a hydroxycarboxylic acid such as hydroxybenzoic acid, glycolic acid, and hydroxyethoxybenzoic acid.

  Moreover, a part of glycol component is aliphatic, alicyclic, and aromatic diol compounds such as BG, propylene glycol, diethylene glycol, hexamethylene glycol, p-xylene glycol, 1,4-cyclohexadimethanol, and bisphenol. It can also be replaced.

  Furthermore, as long as the thermoplasticity is not impaired, a polyester obtained by copolymerizing a trifunctional or higher polyfunctional compound can also be used. Moreover, the polyester which substituted the 1 type (s) or 2 or more types of bifunctional acids, such as a phthalic acid, diphenylcarboxylic acid, a succinic acid, adipic acid, sebacic acid, and P-hydroxybenzoic acid, can also be used. Further, additives such as pigments, heat-resistant materials and fluorescent brighteners can be contained.

  Polyester is produced by sending terephthalic acid and ethylene glycol to an ester reaction apparatus to cause an esterification reaction, and then sending the produced polyester low polymer to a polycondensation reaction apparatus to carry out a polycondensation reaction.

  It is preferable that the polyester waste used by this invention is the recycled polyester waste generate | occur | produced in the manufacturing process of a fiber or a polyester product. The polyester waste is added to the polyester low polymer in the esterification reactor having a reaction temperature of 255 to 260 ° C. The addition ratio of the polyester waste is 5 to 8% by mass, preferably 6 to 7% by mass, more preferably 6% by mass based on the amount of polymer produced per hour. When the addition ratio of the polyester waste is too large, the melting time becomes long, the unmelted polyester waste is clogged in the pipe, and the polyester low polymer cannot be supplied. When the addition ratio is too small, the efficiency of the polycondensation reaction is deteriorated.

  In the method for producing a polyester of the present invention, as the glycol supplied to the continuous reaction apparatus, the same kind of glycol as that constituting the polyester waste usually used as a raw material can be used. Accordingly, aliphatic, alicyclic and aromatic diol compounds such as EG, BG, propylene glycol, diethylene glycol, hexamethylene glycol, p-xylene glycol, 1,4-cyclohexadimethanol, and bisphenol can be used.

  Next, the manufacturing method of the polyester of this invention is demonstrated in detail using drawing.

  FIG. 1 is a side view showing a flowchart for illustrating the method for producing a polyester of the present invention.

  Although FIG. 1 shows a polyester continuous polymerization method having a five-tank configuration, the number of reaction apparatuses is not limited to this.

  In the polyester continuous production method shown in FIG. 1, generally, a slurry of terephthalic acid and ethylene glycol is continuously supplied to a first esterification reaction apparatus 1 in which a polyester low polymer is present in advance. The esterification reaction rate is preferably 90 to 95% by reacting under pressure.

  Next, this is sequentially fed to the second esterification reaction apparatus 2 and reacted under normal pressure or slight pressure to produce a polyester low polymer having an esterification reaction rate preferably increased to 96 to 98%. .

  The polyester waste is added to the second esterification reaction apparatus 2 in an amount corresponding to the amount of polymer produced per hour using the polyester waste addition equipment 6. In order to suppress reaction because the polyester waste contains some water and diethylene glycol components, an alkali compound is added in an amount of 30 to 120 ppm in proportion to the amount of added polyester waste using the alkali compound supply equipment 7. Also, if the equivalent ratio of ethylene glycol component to the acid component in the esterification reaction system and the average reaction time are the same, the esterification reaction rate increases as the reaction temperature increases, but at the same time promotes the production of by-products such as diethylene glycol. Is done. Diethylene glycol causes dyeing differences and strength reduction in the textile field, and in the bottle field, it is one of the components that it is desirable to suppress as much as possible due to hygiene problems.

  Next, the polyester low polymer produced in the second esterification reaction apparatus 2 is continuously passed to the first polycondensation reaction apparatus 3, the second polycondensation reaction apparatus 4, and the third polycondensation reaction apparatus 5. A polyester having a predetermined quality is obtained by a polycondensation reaction during the transportation. In the polycondensation reaction step, ethylene glycol produced by polycondensation is taken out of the reaction system.

  On the other hand, in order to complete an incomplete esterification reaction, the presence of ethylene glycol is indispensable, and the reaction pressure is generally increased in stages by increasing the degree of vacuum.

  The polyester obtained by the present invention is melt-spun, and is particularly suitably used as a vehicle sound-absorbing material for non-woven fabrics, a wet tissue, a uniform for clothing, and a shirt.

  Next, an example is given and the manufacturing method of polyester of the present invention is explained still more concretely. The measuring method of the characteristic value is as follows.

(1) Intrinsic viscosity (hereinafter sometimes abbreviated as IV):
2.0 g of the sample cut out from the chip is weighed, dissolved in orthochlorophenol at a concentration of 0.012 g / ml, cooled to a temperature of 25 ° C., 15 ml is placed in an Ostwald viscometer, and the number of seconds that the molten polymer falls is measured. The intrinsic viscosity was calculated by the following equation.
・ KI = KB × t
(Where KI is relative viscosity, KB is Ostwald viscometer count, and t is the number of seconds the sample solution flows at a temperature of 25 ° C.)
・ Raw IV = 0.0242 × KI + 0.2634
Intrinsic viscosity (IV) = raw IV x f
(Here, f represents standard chip reference value / standard chip measured value number).

(2) Color tone (b value):
The color tone (b value) was measured using an SC3P color machine manufactured by Suga Test Instruments Co., Ltd. The b value represents a yellow-blue hue (+ is yellowish,-is bluish), and the smaller the b value is, the better as long as the color of the polymer does not become extremely small.

(3) Content of diethylene glycol (DEG):
Add 2.5 ml of primary monoethanolamine to 1.0 g of the sample, heat for 40 minutes at a temperature of 280 ° C. under total reflux, and then add the internal standard solution. Further, 40 g of special grade terephthalic acid and 5 ml of primary ethanol are added to prepare a measurement sample. Using the prepared sample for measurement, the content of DEG contained in the polymer was measured using Shimadzu gas chromatography GC-9A (used column: Shimadzu C-R3A).

(4) Carboxyl group content:
The carboxyl group content was determined by dissolving the obtained (copolymerized) polyester in benzyl alcohol and titrating with 0.01 N aqueous sodium hydroxide solution.

(5) Esterification reaction rate:
The esterification reaction rate is determined by the following formula (1) from the acid value (hereinafter sometimes abbreviated as AV) and the saponification value (hereinafter sometimes abbreviated as SV) of the polyester low polymer. For AV, a sample Wg was collected and N.P. Add 50 ml of N dimethylformamide and dissolve. Furthermore, rosolic acid was added as an indicator, and titration was performed with a 0.04N-NaOH aqueous solution to obtain the following formula (2).
Esterification reaction rate = ((SV-AV) / SV)) × 100 (1)
AV = 2.244 × (A1-B1) × F1 / W1 (2)
(Here, A1 is the 0.04N NaOH aqueous solution titration (ml) in the sample, B1 is the 0.04-NaOH aqueous solution titration (ml) in the blank, F1 is the factor of the 0.04N NaOH aqueous solution, and W1 is the sample. The amount collected (g).)

For SV, 0.4 ml of a sample was added with 20 ml of a 0.5N KOH alcohol solution and thermally decomposed at 95 ° C. for 30 minutes. After cooling, 1% phenolphthalein indicator was added and 0.5N—H ₂ SO ₄ aqueous solution was added. It titrated and calculated | required by following formula (3).
SV = 28.05 × (A2-B2) × F2 / W2 (3)
(Where A2 is the 0.5N-H2SO4 aqueous solution titration (ml) in the sample, B2 is the 0.5-H2SO4 aqueous solution titration (ml) in the blank, F2 is the 0.5N-H2SO4 aqueous solution factor, and W2 is the sampling. Represents the amount (g)).

Example 1
Using the equipment shown in FIG. 1, the first esterification reaction apparatus 1 (250 ° C.) is continuously supplied with a slurry of terephthalic acid and ethylene glycol at a rate of 2558 mass% / hour to conduct an esterification reaction. The produced polyester low polymer is supplied to the second esterification reactor. Using the equipment shown in FIG. 1, 148 polyester waste (pulverized polymer produced in the manufacturing process of fibers and polyester products) from the polyester waste addition equipment 6 to the second esterification reactor 2 (255 ° C.) 148 The polyester low polymer produced was continuously added at a rate of mass% / hour, and at the same time, tetraethylammonium hydroxide as an alkali compound was added at a rate of 30 ppm / hour to conduct an esterification reaction. It is routed to the first polycondensation reaction apparatus 3 (7.3 KPa), the second polycondensation reaction apparatus 4 (2.0 KPa), and the third polycondensation reaction apparatus 5 (0.3 KPa). 0.633 polymer (polyester) was obtained. The amount of DEG and the amount of COOH were also low, and the color tone of the obtained polymer had a b value of 7.2. Table 1 shows the physical properties of the obtained polymer. It was confirmed that the polymer could be obtained without any problem in the esterification reaction rate.

(Example 2)
In the same manner as in Example 1, 192% by mass of polyester waste (pulverized polymer produced in the manufacturing process of fibers and polyester products) from the polyester waste addition facility 6 to the second esterification reactor 2 (257 ° C.). Is continuously added at a rate of 80 ppm / hour as an alkali compound, and an esterification reaction is carried out, and the resulting polyester low polymer is continuously in the first weight. Condensation reaction device 3 (7.3 KPa), second polycondensation reaction device 4 (2.0 KPa), and third polycondensation reaction device 5 (0.3 KPa) are passed through and the intrinsic viscosity is reduced to 0. 635 polymer (polyester) was obtained. The amount of DEG and the amount of COOH were also low, and the color tone of the obtained polymer had a b value of 7.3. It was confirmed that the polymer could be obtained without any problem in the esterification reaction rate. The results are shown in Table 1.

(Example 3)
In the same manner as in Example 1, 237% by mass of polyester waste (pulverized polymer generated in the production process of fibers and polyester products) from the polyester waste addition facility 6 to the second esterification reactor 2 (260 ° C.). At a rate of 120 ppm / hour, and at the same time, an esterification reaction is carried out by adding tetraethylammonium hydroxide as an alkali compound at a rate of 120 ppm / hour. Condensation reaction device 3 (7.3 KPa), second polycondensation reaction device 4 (2.0 KPa), and third polycondensation reaction device 5 (0.3 KPa) are routed through and the intrinsic viscosity is obtained by polycondensation reaction. Of 0.634 was obtained. The amount of DEG and the amount of COOH were also low, and the color tone of the obtained polymer had a b value of 6.8. It was confirmed that the polymer could be obtained without any problem in the esterification reaction rate. The results are shown in Table 1.

(Comparative Example 1)
In the same manner as in Example 1, the second esterification reactor 2 (255 ° C.) was charged with 148% by mass of polyester waste (pulverized polymer produced in the production process of fibers and polyester products) from the polyester waste addition facility 6. Hr is continuously added at a rate of / hour to conduct esterification reaction, and the resulting polyester low polymer is continuously produced from the first polycondensation reactor 3 (7.3 KPa), the second polycondensation reactor. 4 (2.0 KPa) and the third polycondensation reaction apparatus 5 (0.3 KPa) via supply, and a polymer having an intrinsic viscosity of 0.629 was obtained by the polycondensation reaction. The amount of DEG and the amount of COOH were high, and the color tone of the obtained polymer had a b value of 8.2. The results are shown in Table 1.

(Comparative Example 2)
In the same manner as in Example 1, 237% by mass of polyester waste (pulverized polymer generated in the manufacturing process of fibers and polyester products) from the polyester waste addition facility 6 to the second esterification reactor 2 (260 ° C.). At a rate of 130 ppm / hr. At the same time as an alkali compound at a rate of 130 ppm / hr to conduct an esterification reaction. Condensation reaction device 3 (7.3 KPa), second polycondensation reaction device 4 (2.0 KPa), and third polycondensation reaction device 5 (0.3 KPa) are transported by way of the polycondensation reaction. A polymer having a viscosity of 0.631 was obtained. The amount of DEG and the amount of COOH were also high, and the color tone of the obtained polymer had a b value of 9.2. The results are shown in Table 1.

1: First esterification reaction device 2: Second esterification reaction device 3: First polycondensation reaction device 4: Second polycondensation reaction device 5: Third polycondensation reaction device 6: Waste polyester addition equipment 7: Alkaline compound Supply equipment

Claims (4)

  In a method for continuously producing polyester by subjecting terephthalic acid and / or a derivative thereof and ethylene glycol as a raw material to an esterification reaction and polycondensation reaction of the obtained polyester low polymer, a reaction temperature of 255 to 260 ° C. Polyester waste is added to the polyester low polymer in the esterification reactor at a ratio of 5 to 8% by mass, and an alkali compound is further supplied in an amount of 30 to 120 ppm based on the polyester waste. .   The method for producing a polyester according to claim 1, wherein the alkali compound is an alkali compound selected from the group consisting of tetraethylammonium hydroxide, potassium hydroxide and sodium hydroxide.   The method for producing polyester according to claim 1 or 2, wherein the polyester waste is recycled polyester waste generated in the production process of fibers or polyester products.   The glycol component used in the esterification reaction is at least one selected from the group consisting of ethylene glycol and 1,4-butanediol. Production method.

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