KR20110046800A - Preparing process of polyethylene terephthalate - Google Patents

Abstract

PURPOSE: A process for preparing polyethylene terephthalate is provided to lower the content of an oligomer compared with polyester obtained by a conventional manufacturing method and to additionally reduce the content of diethylene glycol. CONSTITUTION: A process for preparing polyethylene terephthalate comprises the steps of: adding an antimony compound catalyst, phosphoric acid-based thermal stabilizer, magnesium compound, and acetate compound to a low-molecular-weight polymer prepared by esterification of divalent terephthalic acids which are dibasic acid and ethylene glycol which is divalent alcohol; heating the mixture at 260-290 °C; and performing polycondensation for removing ethylene glycol which is divalent alcohol in high vacuum.

Description

Preparation method of polyethylene terephthalate {Preparing process of polyethylene terephthalate}

The present invention relates to a method for producing polyethylene terephthalate, and more particularly, to reduce the content of oligomers generated during the polymerization of polyester in polyethylene terephthalate (T-DIE) when discharging molten polymer in film processing Of new polyethylene terephthalate, which increases the number of T-die LIP cleaning due to contamination, prevents film streaks, and solves all problems caused by oligomer precipitation on the surface of film or sheet. It relates to a manufacturing method.

Polyethylene terephthalate (hereinafter referred to as "PET") has excellent thermal properties, electrical properties, moisture resistance, water resistance and transparency, and thus is widely used in fibers, optical films, bottles, engineering plastics, and the like. .

In general, polyethylene terephthalate is produced during the manufacturing and processing of oligomers due to side reactions and lowering of the esterification reaction rate. The oligomers thus formed contaminate the tea die during melt polymer discharge during film processing, thereby causing the tea die LIP. There is a disadvantage in that the number of sweeps is increased, and streaking of the film is caused. In addition, it precipitates on the surface of films, sheets, and the like, causing roughness and whitening of the surface properties and deteriorating product value. Therefore, in order to solve this problem, a method of reducing the oligomer content in PET has been examined and many proposals have been made. For example, Japanese Unexamined Patent Application Publication No. 2008-0110605 describes a method for producing polyethylene terephthalate. A method for producing a polyethylene terephthalate and obtaining a solid phase polycondensation thereof using a specific compound containing a jar is described. The method for producing a polyester-based fiber structure and the polyester obtained therefrom are disclosed in JP 2007-224428 A. "Base fiber structure" is a method for producing a polyester fiber structure characterized in that the polyester fiber structure is subjected to contact treatment using an aqueous solution in which a surfactant is dissolved, and the oligomer contained in the polyester fiber structure is extracted and removed. It is started and is open to Japan Nos. 2007-182474 to 2007-182477 disclose acetaldehyde content and oligomer content by a method of incorporating a phosphorus compound into a polyester resin under the name "polyester resin and polyester resin composition thereof and uses thereof". Each discloses a method for reducing In addition, for example, "Under a cyclic oligomer content in a polyester product" of Unexamined-Japanese-Patent No. 2004-190004, Ca ₃ (PO ₄ ) ₂ or Ca in the manufacturing process of polyethylene terephthalate (PET) _By adding at least one selected from calcium phosphate and carboxyphosphoric acid having a structure of ₅ OH (PO ₄ ) _3, the amount of cyclic oligomers can be effectively suppressed, and the amount of cyclic oligomers produced during melt processing in the post-treatment step has been described with respect to reducing, Japanese Laid-Open Patent Publication No. 2000-219731 heading "polyester resin and its manufacturing method" is the occasion of the polyethylene terephthalate melt polymerization by the addition of SO ₃ X compound to polyethylene terephthalate cyclic oligomers amount To suppress the

However, there is a problem to be solved such that the generation of oligomers is not completely effectively suppressed even by the aforementioned conventional methods, and the complexity of the manufacturing process.

It is an object of the present invention to provide a method for effectively reducing the content of oligomers generated during polyester polymerization, thereby providing a novel method for producing polyethylene terephthalate having a low oligomer content.

Another object of the present invention is also to effectively suppress the content of oligomers generated during polyester polymerization to prevent contamination of the die and streaks of the film, and also to solve all the problems caused by the oligomer precipitates on the surface of the film or sheet, etc. It is to provide a novel method for producing a polyethylene terephthalate.

Still another object of the present invention is to provide a polyethylene terephthalate prepared by the above method.

The present invention may also be directed to achieving other objects in addition to the above-described specific objects that may be readily derived by one of ordinary skill in the art from the general description of this specification.

Method for producing a polyethylene terephthalate of the present invention for achieving the above object;

260 to 290 ℃ after adding antimony compound catalyst, phosphate thermal stabilizer, magnesium compound and acetate compound to low polymer produced by esterification using dibasic acid terephthalic acid (TPA) and dihydric alcohol ethylene glycol The polycondensation reaction of heating to and removing ethylene glycol which is a dihydric alcohol under high vacuum is characterized by the above-mentioned.

The polyester according to the present invention may include polyethylene terephthalate, polytrimethylene phthalate, polytetramethylene terephthalate, polycyclohexylenedimethylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate, and the like. Among them, the most widely used polyethylene terephthalate is most preferred.

According to another configuration of the present invention, when preparing a TPA slurry by mixing and stirring the solid dibasic acid terephthalic acid (TPA) and liquid dihydric alcohol ethylene glycol (EG), the TPA to EG molar ratio is 1.05. To 1.20.

According to another configuration of the present invention, the antimony catalyst as the polymerization catalyst is 150 to 250 ppm in terms of antimony atoms, the thermal stabilizer in phosphorus series is 10 to 100 ppm in terms of phosphorus atoms, and the magnesium compound is 50 to 150 ppm in terms of magnesium atoms , The acetate compound is characterized in that 5 to 20ppm is used.

According to another configuration of the present invention, the thermal stabilizer of the acetate compound and phosphorus series is characterized in that it is added to the esterification reaction tube.

According to another configuration of the present invention, the antimony-based catalyst and magnesium acetate hydrate, which are the polymerization catalysts, are introduced into an oligoma transfer line between the esterification reaction tube and the polymerization reaction tube.

According to another configuration of the present invention, the acetate compound is sodium acetate (sodium acetate), copper acetate (copper (II) acetate), iron acetate (iron (II) acetate), palladium acetate (palladium (II) acetate), It is characterized in that the single or two or more selected from silver acetate (silver acetate).

According to another configuration of the present invention, the thermal stabilizer of the phosphorus series in phosphoric acid (H ₃ PO ₄ ), trimethylphosphate ((CH ₃ O) ₃ PO ₄ ), tritetyl phosphate (C ₂ H ₅ O ₃ PO) It is characterized by being selected alone or two or more.

According to another configuration of the present invention, the antimony-based catalyst as the polymerization catalyst is antimony trioxide (Sb ₂ O ₃ ), antimony oxalate, antimony glucoside, antimony butoxide (Antimony butoxide) It is characterized in that the single or two or more selected from.

The method for producing polyethylene terephthalate of the present invention configured as described above not only significantly lowers the content of oligomers as compared to the polyester obtained by the conventional manufacturing method, but also additionally reduces the content of diethylene glycol (DEG), The polyethylene terephthalate prepared according to the present invention can reduce the number of LIP sweeps during film production, prevent streaks of the film, and do not precipitate oligomers on the surface, which does not cause roughness or whitening of the product, resulting in a product value. It is a useful invention to provide an improved polyethylene terephthalate.

EMBODIMENT OF THE INVENTION Hereinafter, this invention is demonstrated in detail by preferable embodiment.

Polyethylene terephthalate according to the present invention is an antimony compound catalyst and a phosphoric acid-based thermal stabilizer, magnesium compound, acetate compound on low polymer produced by esterification reaction using dibasic acid terephthalic acid (TPA) and dihydric alcohol ethylene glycol It is prepared by a polycondensation reaction after the addition of 260 to 290 ° C and heating to remove ethylene glycol which is a dihydric alcohol under high vacuum.

Examples of the polyester include polyethylene terephthalate, polytrimethylene phthalate, polytetramethylene terephthalate, polycyclohexylenedimethylene terephthalate, polyethylene-2,6-naphthalenedicarboxylate and the like. Among them, the most widely used polyethylene terephthalate is most preferred.

TPA slurry is prepared by mixing and stirring terephthalic acid (TPA), which is a solid dibasic acid, and ethylene glycol, which is a liquid dihydric alcohol, according to the present invention, wherein the molar ratio of TPA to EG is most preferably in the range of 1.05 to 1.20.

Based on the weight of the polymer, the antimony catalyst is 150 to 250 ppm in terms of antimony atom, the phosphorus thermal stabilizer is 10 to 100 ppm in terms of phosphorus atom, the magnesium compound is 50 to 100 ppm in terms of magnesium atom, and the acetate compound is 5 to 20 ppm. To use, the melt polymerization temperature is preferably carried out in the range of 260 to 290 ℃.

The antimony-based catalyst is not particularly limited, but may be used in at least one compound selected from antimony trioixde, antimony-tri-acetate, and antimony oxalate.

The compound of the phosphoric acid series is not particularly limited, but at least one compound selected from phosphoric acid and trimethyl-phosphate may be used.

In the polyester composition of the present invention, it is essential to add an acetate compound and a phosphoric acid compound to the low polymer produced by the esterification reaction using terephthalic acid (TPA), which is a dibasic acid, and ethylene glycol, which is a dihydric alcohol. .

The antimony-based compound and magnesium acetate water compound as the polymerization catalyst are added to the oligomer line between the esterification reaction tube and the polymerization reaction tube, and the phosphorus-based compound and the acetate compound are added to the esterification reaction tube.

In general, an ammonium compound of an alkali type is used as a diethylene glycol generation inhibitor, which acts to remove an acid which acts as a catalyst in the production of DEG. It aims to neutralize the acid as alkali. Acids also catalyze the production of DEG but are important catalysts for the esterification reaction. Excessive DEG generation inhibition delays the esterification reaction and causes esterification in the presence of alkali metals, but because alkali metal compounds do not dissolve and are dispersed in the polymer, these substances aggregate and denature or worsen thermal stability. This adversely affects the fiber or film process. Therefore, as a result, the oligomer often increases due to the lowering of the esterification reaction rate.

However, when the acetate compound is used as the DEG generation inhibitor, there is an effect of reducing the oligoma and DEG content in the polyester. Normally DEG is included in the polyester chains and is weak to heat because DEG has a lower molecular weight than polyester. Therefore, pyrolysis occurs due to the property that the polymerization proceeds at a high temperature, so that an oligomer is increased due to pyrolysis in the polyester. Acetate compounds have the property of significantly reducing DEG generation compared to ammonium compounds. Therefore, when the amount of DEG generation is reduced, the effect of reducing the thermal decomposition oligomer content by heat occurs.

As an example of the film manufacturing method, a chip weighed in a scale hopper is introduced into a dryer device to remove moisture, stirred by a steam supply and an internal agitator, and then in a high vacuum. After drying, it is discharged into a storage feeder hopper, and the polymer melted at 280 ° C. is discharged in a film forming process in the direction of a casting drum from a tee die lip to form a sheet in an initial film state. After adjusting the gap of the lip to adjust the thickness, and cooling and solidifying at room temperature using a casting drum to produce an amorphous polyester film, stretching is carried out in the longitudinal and transverse directions using a roll. To prepare a film. However, increasing the oligomer end groups in the polymer may cause pinning arcs due to contamination of the lip, increase in the number of LIP cleaning, static electricity, streaks of the film, and the like. Therefore, according to the present invention described above it was possible to solve this problem by reducing the oligomer content in the polymer.

Hereinafter, the present invention by examples will be described in more detail. The analytical evaluation in each Example and a comparative example was performed as follows.

(1) Intrinsic viscosity measurement [η]

Measuring instrument: DESIGN SCIENTIFIC (OCTAVIS)

Sample Preparation: Samples shall be collected in accordance with the Automatic Sample Preparation Machine Working Standard.

Measuring method: Set about 5.5 ± 0.5ml of sample solution in the prepared OCTB Vis System, set the temperature for 15 minutes, and measure according to the system.

(2) DEG measurement

Instrument: Gas Chromatograph

Sample preparation: Weigh 1.0 ± 0.005 g of sample using a balance, take a 25 ml round flask, dissolve by heating, cool the sample sufficiently, and centrifuge at 3000 RPM for about 3 minutes in a centrifuge. Collect the supernatant from the sample bottle for about 6-7 minutes and close the sample bottle using the sample bottle cap and tongs.

Method of measurement: Place the sample bottle in the sample auto-injector and perform the test according to GC handling standard.

(3) determination of oligoma content

Sample preparation: Samples are taken in a 0.15 ± 0.0005 g weighing 100 ml triangle flask. Take 10 ml of benzyl alcohol (C ₆ H ₅ CH ₂ OH) and add it to the sample. Close the Erlenmeyer flask with a rubber stopper, replace the air with nitrogen using a hose, dissolve and dissolve on the heater for 6 minutes, and open the stopper. Dilute by adding 10 ml of chloroform (possibly Dolby). Add 3 drops of 0.1% phenol red.

Measuring method: The sample is titrated with N / 25-benzyl alcoholic NaOH while stirring (end point is changed from yellow to orange).

% Of reaction = {10-

0.04: NaOH concentration 10: Chloroform 10 ml dilution concentration Titer: Titer of N / 25-NaOH

(4) Melting point (Tm) measurement

Measuring instrument: measured using DSC (NETZ200)

Sample preparation: 4-5 mg polymer pellets.

Measuring method: Measure while raising the temperature from 40 ° C to 280 ° C at a rate of 10 ° C / min.

Example 1

Terephthalic acid 8,313kg / hr, ethylene glycol 3,400 kg / hr was mixed and stirred, added to the esterification reactor (ES1), the temperature was raised to 265 ℃, the esterification reaction was carried out under a 0.9kgf / ㎠G pressure atmosphere.

The ester compound produced in the esterification reactor was transferred to another esterification reactor (ES2), and then 16 ppm of sodium acetate compound and 57 ppm of trimethylphosphate compound were added based on polyethylene terephthalate, the final product produced at 265 ° C. and atmospheric pressure. .

190 ppm of antimony trioxide based on polyethylene terephthalate, which is the final product in the oligoma line transferring the completed ester compound to the polycondensation reaction tube in the esterification reactor (ES2), and 93 ppm of magnesium acetate compound for magnesium atom After the addition, the polycondensation reaction tube was transferred to a polycondensation reaction tube, and then subjected to a polycondensation reaction under a reduced pressure of about 280 ° C. and about 50 torr to prepare polyethylene terephthalate having an intrinsic viscosity of 0.615. Thus measured by the above method for the polyethylene terephthalate prepared the results are shown in Table 1 below.

Example 2

Polyethylene terephthalate was prepared in the same manner as in Example 1, except that 13 ppm of sodium acetate was used.

 Example 3

Polyethylene terephthalate was prepared in the same manner as in Example 1, except that 10 ppm of sodium acetate compound was used.

Example 4

Polyethylene terephthalate was prepared in the same manner as in Example 1, except that 8 ppm of the sodium acetate compound was used.

Comparative Example 1

Polyethylene terephthalate was prepared in the same manner as in Example 1, except that 48 ppm of triethylene ammonium hydrooxide compound was used instead of the sodium acetate compound.

Comparative Example 2

Polyethylene terephthalate was prepared in the same manner as in Example 1, except that 58 ppm of triethylene ammonium hydrooxide compound was used instead of the sodium acetate compound.

A: acetate compound, B: ammonium compound division Example 1 Example 2 Example 3 Example 4 Comparative Example 1 Comparative Example 2 DEG generation inhibitor Kinds A A A A B B Input (ppm) 16 13 10 8 48 58 Intrinsic Viscosity (IV) 0.615 0.615 0.615 0.615 0.615 0.615 DEG content (wt%) 0.76 0.79 0.85 0.90 1.05 1.00 Melting point (Tm, ℃) 255.5 255.4 255.4 255.3 254.8 254.9 Oligomer content (eq / TON) 35 35 35 36 44 44 Film workability
(LIP cleaning cycle, stripe) ◎ ◎ ◎ ○ X X

◎: Very good ○: Excellent △: Normal X: Poor

As can be seen in the above table, according to the present invention, the polyethylene terephthalate using the acetate compound was confirmed that the oligomer is significantly reduced in the polyethylene terephthalate compared with the ammonium compound of the comparative example, and the DEG content was also reduced.

Claims (8)

260 to 290 ℃ after adding antimony compound catalyst, phosphate thermal stabilizer, magnesium compound and acetate compound to low polymer produced by esterification using dibasic acid terephthalic acid (TPA) and dihydric alcohol ethylene glycol And a polycondensation reaction to remove ethylene glycol which is a dihydric alcohol under high vacuum. The molar ratio of TPA to EG is 1.05 to 1.20 when the TPA slurry is prepared by mixing and stirring the terephthalic acid (TPA), which is a dibasic acid as a solid, and ethylene glycol (EG), which is a liquid, divalent alcohol. Method for producing a polyethylene terephthalate, characterized in that the range. The antimony catalyst according to claim 1, wherein the antimony catalyst is 150 to 250 ppm in terms of antimony atom, the phosphorus thermal stabilizer is 10 to 100 ppm in terms of phosphorus atom, and the magnesium compound is 50 to 150 ppm in terms of magnesium atom, an acetate compound. Method for producing a polyethylene terephthalate, characterized in that using 5 to 20ppm. The method according to claim 1, wherein the acetate compound and the phosphorus-based heat stabilizer are added to an esterification reaction tube. The method for producing polyethylene terephthalate according to claim 1, wherein the antimony catalyst and magnesium acetate hydrate, which are the polymerization catalysts, are introduced into an oligoma transfer line between an esterification reaction tube and a polymerization reaction tube. According to claim 1, wherein the acetate compound is sodium acetate (sodium acetate), copper acetate (copper (II) acetate), iron acetate (iron (II) acetate), palladium acetate (palladium (II) acetate), silver acetate ( silver acetate) is selected from the group consisting of single or two or more polyethylene terephthalate. The heat stabilizer of claim 1, wherein the thermal stabilizer is selected from phosphoric acid (H ₃ PO ₄ ), trimethylphosphate ((CH ₃ O) ₃ PO ₄ ), and tritetylphosphate (C ₂ H ₅ O ₃ PO). Method for producing polyethylene terephthalate, characterized in that the single or two or more. The antimony catalyst according to claim 1, wherein the antimony catalyst is selected from antimony trioxide (Sb ₂ O ₃ ), antimony oxalate, antimony glucoxide, and antimony butoxide. Method for producing polyethylene terephthalate, characterized in that the single or two or more kinds.