JP2002249557A - Method for preparing polyester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method that makes it possible to prepare a high-quality polyester consistently, by effectively utilizing waste polyester generated in polyester production steps or the like. SOLUTION: This polyester is prepared by supplying, as raw materials, a dicarboxylic acid and/or an ester forming derivative thereof, as well as a glycol and/or an ester forming derivative thereof, to the ester reaction in order to perform esterification or ester interchange reaction, and then supplying the obtained ester oligomers to the polycondensation reaction in order to perform polycondensation, wherein waste polyester is melted by using a melt extruder, and then the melt is supplied to the ester reaction or the polycondensation reaction in order to produce a polyester polymer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing a polyester polymer of stable quality by feeding waste polyester during an esterification or transesterification reaction (hereinafter referred to as an ester reaction) or during a polycondensation reaction. .

[0002]

2. Description of the Related Art Conventionally, polyester has many uses as a molding material for fibers, films, plastics and the like. In these manufacturing processes, fibrous, film,
Resin-like polyester waste is generated.

[0003] Various methods have been proposed as a method for recovering these, such as a method in which waste polyester is depolymerized with an excess of ethylene glycol and then esterified with methanol and recovered as dimethyl terephthalate, or a method of recovering terephthalic acid and ethylene glycol. There is a method of directly adding waste polyester to the reaction system.

Japanese Patent Application Laid-Open No. Sho 54-111562 discloses that when a low-viscosity, low-molecular-weight polyester prepolymer is introduced under high-temperature and reduced-pressure conditions, and a stream is taken out from the other end as a high-viscosity, high-molecular-weight polyester, debris is removed. Are disclosed.

[0005] In the method disclosed in the publication, waste polyester is charged into a reactor which is the final step of a polyester polymerization method called a polymerization finisher. However, when the waste polyester is charged in the polymerization finisher, it must be charged under reduced pressure, so air (especially oxygen) is apt to be mixed in. However, a problem such as a decrease in viscosity was easily caused.

Further, the publication discloses that the mixing ratio of the waste polyester is 20 to 50% by weight, and there is a problem that when the foreign matter mixing ratio in the waste polyester is large, the quality of the obtained polyester is not stable. there were.

Japanese Patent Application Laid-Open No. 58-13531 discloses that when polyester waste is depolymerized with glycol, a bishydroxyalkyl terephthalate (hereinafter referred to as BHAT) in a heat-melted state is present in advance, and the amount of BHAT and the amount of glycol are determined. BHA after depolymerization
A method of allowing T to stand under specific conditions is disclosed.

However, the method disclosed in the publication can be used in a batch polymerization method, but cannot be applied to a continuous polymerization method. Batch polymerization has the disadvantage that the quality tends to change during the discharge time of the polyester polymer. On the other hand, in the continuous polymerization, since the polymerization reaction is always progressing, a stable polyester polymer can be obtained without delay in the discharge time.

As described above, according to the conventional method, it is difficult to obtain a stable polyester while continuously supplying waste polyester during the polymerization reaction step of the polyester polymer.

[0010]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for producing a polyester, which makes it possible to produce a high-quality polyester stably by effectively utilizing waste polyester generated in a polyester production process or the like. It is in.

[0011]

In order to achieve the above object, the present invention has the following arrangement. That is, dicarboxylic acid and / or an ester-forming derivative thereof, and glycol and / or an ester-forming derivative thereof are supplied as raw materials during an ester reaction to carry out an ester reaction or a transesterification reaction, and to obtain an obtained ester low polymer. In a method for producing a polyester by supplying during the polycondensation reaction and performing polycondensation, the waste polyester is melted using a melt extruder, and then fed during the ester reaction or during the polycondensation reaction, and the polyester polymer is supplied. Is a method for producing a polyester.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

The present invention relates to dicarboxylic acids and / or their ester-forming derivatives, glycols and / or
Or, an ester-forming derivative thereof is used as a raw material to supply an ester reaction or a transesterification reaction during the ester reaction, and the resulting ester low polymer is supplied during the polycondensation reaction to produce a polyester. In the method, a waste polyester is melted using a melt extruder and then fed during an ester reaction or a polycondensation reaction to obtain a polyester polymer.

The polyester used in the present invention is not particularly limited. For example, in the case of polyethylene terephthalate, terephthalic acid (hereinafter, referred to as TPA) and ethylene glycol (hereinafter, referred to as EG) slurried by a slurry mixer are esterified. The polyester low polymer produced after being supplied to the reaction apparatus and undergoing the esterification reaction can be produced by subsequently supplying to the polycondensation reaction apparatus and performing a polycondensation reaction.

In the present invention, the waste polyester is
Polyester waste and P generated in various processes for manufacturing polyester products such as fibers, films and plastics
It refers to a used PET molded article such as an ET bottle, and a recycled resin of 100% polyester.

Hereinafter, the present invention will be described with reference to the drawings. In the following description, EG is used as the glycol component, but the present invention is not limited to EG alone.

FIG. 1 is a schematic diagram illustrating the method of the present invention. In FIG. 1, TPA and EG are mixed in a slurry mixer 1
To a constant molar ratio to form a slurry. Using this slurry as a raw material, a slurry supply pump 2
To the esterification reactor 3. In the method of FIG. 1, a diagram is shown in which waste polyester is melted and supplied to the ester reactor 3 by a melt extruder.

In the present invention, the waste polyester needs to be supplied using a melt extruder. If air (especially oxygen) is mixed in a reaction process such as an ester reaction or a polycondensation reaction, the polymer is oxidatively decomposed.

In the method of feeding using a melt extruder as in the present invention, the polymer is sealed and extruded in the extruder, so that it is not in contact with air (particularly oxygen), so that oxidative decomposition of the polymer occurs. Also, there is no problem such as deterioration of color tone and decrease in viscosity of the molten polymer due to increase in the number of carboxyl end groups. In addition, in the case of using a melt extruder, it can be supplied even during a reaction in any pressure range such as normal pressure, pressurization, and reduced pressure.

Further, when a melt extruder is used, the supply amount of the waste polymer can be arbitrarily set, and the set supply amount can be kept constant, and the quality of the obtained polyester is remarkably improved. Easy to stabilize. Furthermore, unlike the conventional method in which chips of waste polyester are directly charged into the reaction tank, the waste polyester is melted and supplied. The unmelted polymer is trapped in the filter and no clogging of the filter occurs.

The waste polyester needs to be supplied during the ester reaction or the polycondensation reaction. Figure 1
In the above, the supply of the waste polyester is supplied to the ester reactor 3, but may be supplied to any of the esterification reactor 4 and the polycondensation reactors 5 to 7. When supplying using
Over time, the tip nozzle of the melt extruder becomes unable to perform stable discharge with contamination. However, when supplied in the ester reactors 3 and 4 and the polycondensation reactor 5 shown in FIG. 1, the effect of washing with EG vapor is obtained, and the phenomenon that the tip nozzle becomes dirty is greatly reduced. Therefore, it is more preferable that the waste polyester is supplied using the melt extruder at the positions of the ester reactors 3 and 4 and the polycondensation reactor 5.

In the esterification reactor 3, preferably 2
The reaction is performed under the conditions of 00 to 270 ° C. and 0.05 to 0.5 MPaG, and the mixture is supplied to the esterification reactor 4. In the esterification reaction, it is preferable to add a polymerization catalyst and, if necessary, a pigment. The polymerization catalyst and the pigment are EG
Is dissolved or dispersed and charged. The esterification reaction is almost completed in the esterification reaction device 4 in this way, and the produced polyester low polymer is supplied to the polycondensation reaction device in the next step.

In the polycondensation reactors 5, 6, and 7, preferably, the temperature and the degree of vacuum are gradually increased in the range of 200 to 300 ° C. and 0.1 to 10 kPaabs, whereby a polyester polymer is synthesized. The esterification reactor 4 and the polycondensation reactors 5, 6, and 7 have wet condensers 9 to 12, respectively.
Is provided, and the distillate EG generated by the reaction is taken out as a concentrated liquid here.

The method for producing the polyester of the present invention may be a continuous type or a batch type.

It is preferable that the waste polyester is melted and supplied using a melt extruder while glycol or a derivative thereof is added inside the melt extruder.

By adding glycol or a derivative thereof inside the melt extruder, depolymerization starts inside the melt extruder and proceeds. Therefore, when supplying high-melting-point, high-viscosity waste polyester, the viscosity is reduced by passing the mixture through a melt extruder while adding glycol or a derivative thereof, and the discharge and supply from the tip nozzle become smooth. Further, by lowering the viscosity, the melting temperature of the melt extruder can be lowered.

Further, in the present invention, by supplying the waste polyester while depolymerizing it with glycol or a derivative thereof, the viscosity can be made close to that of the low-viscosity polymer during the ester reaction and the polycondensation reaction, so that the inside of the reaction is uniform. Therefore, stable reactivity can be obtained. As the glycol or its derivative, ethylene glycol or 1,4-butanediol can be used, but is not particularly limited.

When the waste polyester is melted and supplied using a melt extruder, the mixing ratio with the polymer is 2%.
It is preferably 0% by weight or less.

Since waste polyester is generated in various manufacturing processes of fibers, films, plastics, and the like, the mixing ratio of foreign substances contained in the polymer is naturally not constant.

Therefore, it is preferable that the mixing ratio of the waste polyester is low because the quality of the obtained polyester polymer is stable. Furthermore, even in the case of supplying waste polyester having a high foreign matter mixing ratio, it is possible to avoid a deterioration in the quality of the polyester polymer by setting the mixing ratio of waste polyester to preferably 20% or less.

Further, a polymer having a low viscosity and a low molecular weight can be used after pulverization. As for the high-viscosity, high-molecular-weight polymer, a chipped product can be used as a raw material as it is, and a gut or lump can be used after being pulverized. After fiberization, if oil agent adheres, wash with hot water,
If no oil agent is adhered, it can be used as a raw material after pelletizing with a pelletizer as it is.

The polyester in the present invention is obtained by using TPA or an ester-forming derivative thereof as a dicarboxylic acid,
Polyester containing G, 1,4 butanediol (hereinafter referred to as BG) or an ester-forming derivative thereof as a glycol component can be used, and polyethylene terephthalate or polybutylene terephthalate is preferable.

A part of the TPA component is, for example, 5-sodium sulfoisophthalic acid, 5-potassium sulfoisophthalic acid, p-β-hydroxyethoxybenzoic acid, p-
Hydroxybenzoic acid, isophthalic acid, 4,4'-diphenylsulfonedicarboxylic acid, 4 ', 4-diphenylmethanedicarboxylic acid, 4', 4-diphenyletherdicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 1,2 '
-Diphenoxyethane, p, p'-dicarboxylic acid, 2,
6-naphthalenedicarboxylic acid, adipic acid, sebacic acid or other bifunctional carboxylic acid or an ester-forming derivative thereof, or a part of the glycol component is trimethylene glycol, tetramethylene glycol, hexamethylene glycol, diethylene glycol, triethylene glycol, Ethylene glycol, polyethylene glycol, 1,4
-Substituted by an aliphatic, alicyclic or aromatic dioxy compound such as cyclohexanediol, 1,4-cyclohexanedimethanol, 1,4-bis-β-hydroxyethoxybenzene, bisphenol A or an ester-forming derivative thereof A copolymer polyester in which 70 mol% or more of the chain repeating units are ester units selected from ethylene terephthalate units and tetramethylene terephthalate units may be used.

[0034]

The present invention will be described in more detail with reference to the following examples. In Examples and Comparative Examples, a continuous polyester polymerization apparatus having the form shown in FIGS. 1 and 2 was used.

Now, the present invention will be described in further detail with reference to Examples. In addition, each characteristic value in an Example was implemented by the following measuring methods. (1) Intrinsic viscosity (ηc) Measured at 25 ° C. using orthochlorophenol as a solvent. (2) Carboxyl group content [COOH amount] Dissolve the obtained polyester in benzyl alcohol,
It was determined by titration with a 0.01 N aqueous sodium hydroxide solution. (3) DEG amount The obtained polyester was decomposed by heating using monoethanolamine, and methanol was added to the product, and PET (BH
T) was precipitated, and DEG in the filtrate was measured by gas chromatography. (4) Color tone (b value) This was performed using an SM color machine manufactured by Suga Test Instruments Co., Ltd.

The b value is preferably around 0, and as it becomes larger than 0, the yellow color tends to increase. As the value becomes smaller than 0, the blue color tends to increase. Example 1 Using the production facility shown in FIG.
h, EG was supplied to the slurry mixer 1 at 134 kg / h, slurried, and then supplied to the esterification reactor 3 via the slurry supply pump 2. At this time, a waste polyester having an IV of 0.52 was melted at a melting temperature of 285 ° C. and supplied at a mixing ratio of 10% using a melt extruder (extruder) at the position of the esterification reactor 3. Next, the solution was transferred to the esterification reactor 4, and phosphoric acid 54 g / h was used as a coloring inhibitor, and antimony trioxide 108 g was used as a polymerization catalyst.
/ H, 36 g / h of cobalt acetate as a complementary colorant, and 1440 g / h of titanium dioxide as a matting agent. Next, the solution was transferred to a polycondensation reaction apparatus 5 and a polycondensation reaction was performed under the conditions shown in Table 1. The IV, [COOH] amount, DEG amount, and b value of the polyester obtained through the polycondensation reactors 6 and 7 were measured and are shown in Table 1.

The obtained polyester was melted, filtered through a stainless steel non-woven fabric filter having an absolute filtration diameter of 15 μm, and then discharged from a die having 36 holes. Spinning temperature is 2
At 90 ° C., the discharge amount was adjusted so that the single yarn fineness was 2.2 dtex. After discharging, the discharged yarn is cooled by a standard method,
After refueling, entanglement was imparted and wound up by a winder via a take-up roller. At this time, the speed (spinning speed) of the take-off roller is 60
00 m / min.

Table 1 shows the average number of yarn breaks per ton when spinning about 10 tons.

In Example 1, waste polyester is supplied by using a melt extruder. Since the waste polyester is not in contact with air (especially, oxygen), it is difficult to be thermally decomposed.
The DEG amount was also a low value, and the color tone b value was at a level without any problem. The average of the number of times of thread breakage was 0.7 times / ton, and there was no problem as compared with the number of times of normal thread breakage.

Examples 2 to 5 After the waste polyester was melted using a melt extruder, the polyester was obtained in the same manner as in Example 1 except that the place of supply was changed.

Also in Examples 2 to 5, since the waste polyester is supplied using a melt extruder, it does not come into contact with air (especially oxygen), so that it is hardly subjected to thermal decomposition.
H] and DEG were also low, and the color tone b value was also at a level without any problem. The average of the number of times of thread breakage was not inferior to the normal number of times of thread breakage.

After the production of the polyester, the tip nozzle of the melt extruder was observed. As a result, when the polyester was supplied by the ester reactors 3 and 4 and the polycondensation reactor 5 shown in FIG. In the polycondensation reactors 6 and 7, dirt was slightly conspicuous.

Examples 6 to 7 In the same manner as in Example 1 except that the waste polyester IV was melted by using a melt extruder and the place of supply was changed.
Polyester was obtained.

Even when a high-viscosity waste polyester having a high IV was supplied, the [COOH] amount and the DEG amount were also low, and the color tone b value was at a level without any problem. The average of the number of times of thread breakage was not inferior to the normal number of times of thread breakage.

After the polyester was manufactured, the tip nozzle of the melt extruder was observed. As a result, when the polyester was fed to the ester reactors 3 and 4 and the polycondensation reactor 5 shown in FIG. In the polycondensation reactors 6 and 7, dirt was slightly conspicuous.

Further, since EG was added inside the melt extruder and the viscosity of the polymer to be supplied was low even when the viscosity of the supplied polymer was low, the load was small and the energy loss was small. In addition, there was no problem when the melt extruder was stopped and then heated again to start feeding.

As described above, in the supply of the waste polyester using the melt extruder, the influence of the quality of the waste polyester is small, and the waste polyester can be stably supplied even in a reaction system under normal pressure, pressure, and reduced pressure. No quality polyester could be obtained.

Examples 11 and 12 Polyesters were obtained in the same manner as in Example 6, except that ethylene glycol was not added into the melt extruder and the location of the waste polyester was changed.

Also in Examples 11 and 12, since the waste polyester is supplied using a melt extruder, it does not come into contact with air (particularly oxygen), so that it is hardly subjected to thermal decomposition.
The OOH] amount and the DEG amount were also low values, and the color tone b value was at a level without any problem.

The average of the number of times of thread breakage was not inferior to the normal number of times of thread breakage.

However, since EG was not added into the melt extruder, the viscosity of the molten polymer was high, and the load of the melt extruder increased compared to Examples 6 and 9, resulting in a large energy loss. Further, after the melt extruder was stopped, it was heated again, and when the supply was started, a situation in which the polymer carbonized inside the melt extruder was difficult to discharge was sometimes observed.

Comparative Examples 1 and 2 Polyester was obtained in the same manner as in Example 1 except that the waste polyester was charged by using a rotary chip feeding machine.

In Comparative Example 1, the quality of the obtained polyester was stable, but when the polyester was supplied, EG vapor leaked out, which was very dangerous for safety.

In Comparative Example 2, since the waste polyester was supplied under reduced pressure, air was mixed into the reactor and oxidatively decomposed by contact with air (particularly oxygen).
[COOH] amount decreased. In addition, an increase in the amount of DEG and deterioration of the color tone b value occurred, and it was not possible to obtain a polyester of stable quality.

Further, in Comparative Examples 1 and 2, since the waste polyester was charged into the reaction tank as chips, when the waste polyester was melted and transferred to the next step, the unmelted polymer was added to the filter installed between the steps. Was caught and filter clogging occurred.

Further, the average of the number of times of thread breakage was larger than the number of times of normal thread breakage, and the operability was poor.

Examples 13 and 14 Except for changing the mixing ratio when supplying waste polyester,
A polyester was obtained in the same manner as in Example 1. Example 1
In Nos. 3 and 14, the waste polyester is supplied using a melt extruder, so that it does not come into contact with air (particularly oxygen), so that it is hardly subjected to thermal decomposition. Therefore, the [COOH] amount and the DEG amount were also low values, and the color tone b value was at a level without any problem. The average of the number of times of thread breakage was not inferior to the normal number of times of thread breakage.

Comparative Examples 3 and 4 Except for changing the mixing ratio when supplying the waste polyester,
A polyester was obtained in the same manner as in Comparative Example 1. If the mixing ratio is high, the time when the waste polyester is supplied under reduced pressure is long, the proportion of air mixed into the reactor is high, and the oxidative decomposition is severely caused by contact with air (particularly oxygen).
[COOH] content was greatly reduced, and IV was also significantly reduced. In addition, the DEG amount was greatly increased, and the color tone b value was degraded. As a result, it was not possible to obtain a stable quality polyester due to the influence of waste polyester.

The average of the number of times of thread breakage was considerably larger than the normal number of times of thread breakage, and the operability was greatly inferior.

Further, as in Comparative Examples 1 and 2, Comparative Examples 3 and 4
In this case, since the waste polyester was put into the reaction tank as chips, when the waste polyester was melted and transferred to the next step, the unmelted polymer was caught by the filter installed between the steps, and the filter was clogged.

As described above, after the waste polyester is melted by using a melt extruder, during the ester reaction, or
By supplying during the polycondensation reaction to obtain a polyester polymer, waste polyester generated in the production process and the like can be effectively used, and high-quality polyester can be produced stably.

[0062]

[Table 1]

[0063]

[Table 2]

[0064]

According to the present invention, high quality polyester can be stably produced by effectively utilizing waste polyester generated in the production process and the like.

[Brief description of the drawings]

FIG. 1 is a schematic view showing an example of a polyester production step of the method according to the present invention.

FIG. 2 is a schematic view showing an example of a polyester production process according to a conventional method.

[Explanation of symbols]

 1: Slurry mixer 2: Slurry supply pump 3, 4: Esterification reactor 5, 6, 7: Polycondensation reactor 8: Rectification tower 9, 10, 11, 12: Wet condenser 13: Melt extruder 14 :filter

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 67:00 C08L 67:00 F term (Reference) 4F301 AA25 BF16 BF32 CA09 CA23 CA36 4J029 AA03 AB04 AB05 AC01 AE01 AE03 BA02 CB06A HA01 HA05 HA07 HB01 HB07 HB09 JE162 KB03 KB11 KE05 KG02 4L035 BB21 BB34

Claims (3)

[Claims] 1. An esterification reaction or a transesterification reaction is carried out by supplying dicarboxylic acid and / or an ester-forming derivative thereof and glycol and / or an ester-forming derivative thereof as raw materials during an ester reaction,
In a method for producing a polyester by supplying the obtained ester low polymer during the polycondensation reaction and performing polycondensation, the waste polyester is melted using a melt extruder, and then the polyester is melted during the ester reaction or during the polycondensation reaction. Supply during,
A method for producing a polyester, comprising obtaining a polyester polymer. 2. The polyester production method according to claim 1, wherein the waste polyester is melted and supplied using a melt extruder while glycol or a derivative thereof is added inside the melt extruder. 3. The method according to claim 1, wherein the glycol is ethylene glycol or 1,4 butanediol.
Or the method for producing a polyester according to 2.