JPH11286538A - Aromatic polyester and method for producing the same - Google Patents

Abstract

(57) Abstract: In a method for producing a polyester, the amount of black foreign substances generated in a polymer is reduced while using an Sb compound as a polycondensation catalyst. An aromatic polyester produced from an aromatic dicarboxylic acid and a glycol or a lower alkyl ester of an aromatic dicarboxylic acid and a glycol, using a Sb compound as a polymerization catalyst and orthophosphoric acid as a stabilizer, wherein the Sb compound And the residual amount of orthophosphoric acid in the polymer is represented by the following formula (1)
And an aromatic polyester satisfying (2). 50 ≦ Sb ≦ 500 (1) 0.5 ≦ P ≦ 70 (2) (Sb and P are residual concentrations of each element in polymer (ppm))

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an aromatic polyester and a method for producing the same. More particularly, the present invention relates to an aromatic polyester having a particularly small amount of foreign matter due to a polycondensation catalyst in a polymer and having excellent moldability and molded article quality. It relates to the manufacturing method.

[0002]

2. Description of the Related Art Polyesters represented by polyethylene terephthalate are excellent in mechanical properties, heat resistance, weather resistance, electric insulation resistance and chemical resistance, and are widely used as fibers, bottles, films and other molded products.

Such polyesters have different required properties in each application, but in the production of aromatic polyesters, a polycondensation catalyst is required for the reaction to proceed smoothly, and various metal compounds have been proposed as polycondensation catalysts. Have been.

[0004] Among them, Sb compounds such as antimony trioxide are
It is widely used as an inexpensive catalyst having high polymerization activity. However, these catalysts also have problems,
The compound is reduced to produce metallic Sb and other foreign substances, which darkens the color of the polymer and deteriorates the process condition,
It may deteriorate the quality of molded products.

[0005] Various studies have hitherto been made on reducing foreign matter in polymers using an Sb compound as a polycondensation catalyst. For example, JP-A-1-75628 and JP-A-2-34
No. 20 discloses that an Sb compound is added to an EI reaction polymer at an early stage of a transesterification (hereinafter sometimes abbreviated as EI) reaction,
A technique has been proposed in which the polymer is used as both a catalyst for polycondensation and polycondensation, and the amount of foreign substances in the polymer is reduced by the amount of no additional EI catalyst added. These techniques are not limited to EI polymers. In this regard, the present invention
It differs greatly from the technology described in the above publication in that it focuses on the type of phosphorus-based stabilizer and the quality of the oligomer when the Sb compound is added.

Japanese Patent Application Laid-Open No. 61-231025 proposes a technique in which an Sb compound is used as a polycondensation catalyst, and a small amount of terephthalic acid is added in the latter half of the polymerization to reduce foreign substances deposited on a spinneret during spinning. I have. However, this technology does not mention black foreign matter in the polymer, and in fact, it is not possible to implement this technology at a business level to stably bring out good polymer quality and the effect of foreign matter reduction. Difficult,
It has not been put to practical use.

JP-A-54-39490 and JP-A-60-675
No. 29 proposes a technique in which an Sb compound and a phosphorus compound are mixed in advance by heating under appropriate conditions and used as a polycondensation catalyst. The problems and effects of this technique are also limited to the reduction of spinnerets during spinning, and are different from the reduction of black foreign particles in polymers. In addition, this technique does not mention the quality of the oligomer or the type of phosphorus compound immediately before the addition of the catalyst.

[0008]

An object of the present invention is to reduce the amount of black foreign matter generated in a polymer while using an Sb compound as a polycondensation catalyst.

[0009]

That is, the present invention provides a method for producing an aromatic dicarboxylic acid and a glycol or a lower alkyl ester of an aromatic dicarboxylic acid and a glycol using a Sb compound as a polymerization catalyst and orthophosphoric acid as a stabilizer. Aromatic polyester in which the residual amounts of the Sb compound and orthophosphoric acid in the total polyester satisfy the following formulas (1) and (2): 50 ≦ Sb ≦ 500 (1) 0.5 ≦ P ≦ 70 (2) (Sb and P are residual concentrations (ppm) of each element in the polymer).

Hereinafter, the present invention will be described in detail. The aromatic polyester of the present invention is composed of an aromatic dicarboxylic acid component and a glycol component. The aromatic dicarboxylic acid component may be derived from any of aromatic dicarboxylic acids and lower alkyl esters of aromatic dicarboxylic acids.

Examples of the aromatic dicarboxylic acid component include terephthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, and diphenyletherdicarboxylic acid. Of these, terephthalic acid and naphthalenedicarboxylic acid are preferred.

The glycol component includes aliphatic diols such as diethylene glycol, triethylene glycol, tetramethylene glycol, and hexamethylene glycol; alicyclic diols such as cyclohexanediol and cyclohexanedimethanol; and aromatic compounds such as naphthalene diol, bisphenol A, and resorcinol. Group diols and the like can be exemplified. Of these, ethylene glycol and tetramethylene glycol are preferred. Note that, within a range in which the aromatic polyester is substantially linear, a polyfunctional compound having three or more ester-forming functional groups in one molecule, for example, glycerin, trimethylolpropane, pentaerythritol, trimellitic acid, Trimesic acid, pyromellitic acid, tricarballylic acid, etc. may be copolymerized,
If necessary, a monofunctional compound having one ester-forming functional group in one molecule, for example, o-benzoylbenzoic acid,
Naphthoic acid may be used as a small amount of a copolymer component.

The Sb compound used in the present invention is an Sb compound having a polymerization catalyzing ability.

Examples of the Sb compound include oxides such as antimony trioxide, antimony tetroxide and antimony pentoxide; halides such as antimony trichloride and antimony tribromide; acid salts such as antimony acetate, and alcoholates such as antimony glycolate. preferable. Of these, oxides are preferred.

When these Sb compounds are used as a polymerization catalyst and polymerized by a conventional method, more or less Sb
Black foreign matter due to the compound is generated.

The present inventors have conducted intensive studies on a method for reducing these, and as a result, have found that the higher the acidity of the oligomer when the Sb compound is added as a polycondensation catalyst, the more the generation of black foreign substances can be suppressed. Although the apparent reason for this phenomenon is unknown, the present inventors presume that the acidic nature of the oligomers, i.e., protons, is to suppress the generation of metallic Sb, which is thought to be caused by the conversion of the Sb compound.

According to the findings of the present inventors, orthophosphoric acid should be used as a stabilizer for suppressing the generation of black foreign matter in a polymer.

The orthophosphoric acid should be added at the same time as the addition of the Sb compound or within 15 minutes before and after the addition of the Sb compound. Of course, there is a method in which the acidity of the oligomer is reduced by the esterification rate (DE rate) in the case of the direct weight method, and the Sb compound is added while the carboxyl terminal is still large. However, when the Sb compound and orthophosphoric acid are added so as to satisfy the conditions of the present invention, surprisingly, the amount of COOH end groups of the oligomer at the time of adding the catalyst is 350 eq / T or less, further 250 eq.
Even in the case of a polymerization facility where the ratio becomes / T, generation of foreign matter can be suppressed.

Specific equipment capable of controlling the oligomer to have a COOH terminal group amount of not more than 350 eq / T includes, for example, a Bx-type direct weight method, a direct weight equipment capable of operating only at a high charged molar ratio of TA / EG, Bx-type EI polymerization method and the like can be exemplified. According to the method for producing an aromatic polyester of the present invention,
Even in the case of producing polyester with such equipment, an effect of effectively suppressing black foreign matter can be obtained.

Regarding the method of addition, it is necessary that the time of addition of orthophosphoric acid is the same as the time of addition of the Sb compound or within 15 minutes before and after the time of addition of the Sb compound. If orthophosphoric acid is added to the reaction system earlier than this, orthophosphoric acid is discharged from the reaction system together with distillate water and distillate glycol, or ethylene glycol (hereinafter abbreviated as DEG) is a by-product. May be over-copolymerized, making it difficult to control the reaction and quality. If the addition time of orthophosphoric acid is later than this, a large amount of black foreign matter is generated in the reaction system before the addition of orthophosphoric acid, and the effect of reducing the black foreign matter is reduced.

The amount of orthophosphoric acid added is such that the concentration of elemental phosphorus in the entire polyester is 0.5 ppm or more and 70 ppm or less.
If the amount is less than this range, not only the effect of suppressing the black foreign matter is lost, but also the effect as a stabilizer is not exhibited, and the thermal stability is reduced. Exceeding this range deteriorates the thermal stability of the polyester and causes acetaldehyde during molding (hereinafter, referred to as acetaldehyde).
AA) (abbreviated as AA) or causes a significant drop in IV. Therefore, the concentration of phosphorus element in the total polyester is preferably 0.5 to 70 ppm, more preferably 3 to 50 ppm, and particularly preferably 5 to 40 ppm.

The amount of the Sb compound added is Sb in the total polyester.
It is the amount that the element concentration becomes 50 to 500 ppm. It is preferable to appropriately adjust the addition amount because it varies depending on the application of the polymer and the reaction apparatus, but the concentration of the Sb element in the entire polyester is preferably adjusted.
If the amount is more than 500 ppm, the color of the polyester becomes dark even when the method of the present invention is used, and the amount of black foreign matters increases, so that the quality of the molded product cannot be satisfactory. If the concentration of the Sb element is less than 50 ppm, sufficient polymerization activity cannot be obtained, and productivity is not sufficient for industrial production of polyester. Therefore, the concentration of the Sb element in the total polyester is 50 to 500 ppm, preferably 80 to 400 ppm, and more preferably 100 to 300 ppm.

In the aromatic polyester of the present invention, if necessary, other additives such as a tinting agent, a coloring agent, an antioxidant, an ultraviolet absorber, an antistatic agent and a flame retardant may be used.

In the method for producing an aromatic polyester of the present invention, after the completion of the melt polycondensation, it can be extruded, cooled in a suitable cooling medium, for example, water, cut into a suitable size, and cut into chips. The tip may be a rectangular parallelepiped, a cylinder, a die, or a sphere.

The aromatic polyester of the present invention may be further subjected to solid-state polymerization. At this time, an aromatic polyester having an intrinsic viscosity in a desired range can be obtained.

[0026]

The present invention will be described below in detail with reference to examples. In the examples, "parts" means parts by weight. The methods for measuring various characteristics in the examples are as follows.

1) Intrinsic viscosity number [η]: Calculated from the solution viscosity measured at 35 ° C. using a mixed solvent of phenol / tetrachloroethane (weight ratio 60/40).

2) Hue The polymer was heat-treated in a dryer at 140 ° C. for 60 minutes and dried. The polymer was measured using a color machine CM-7500 type color machine.

3) Measurement of amount of metal The amount of metal (unit: ppm) in the polymer was measured by X-ray fluorescence (Rigaku Electric Industry Co., Ltd., X-ray fluorescence type 3270) by a predetermined method.

4) Analysis of black foreign matter: 1 g of the chip was washed thoroughly with acetone and then with chloroform in a clean bench to remove foreign matter from disturbance. 1 g of the chip in 20 g of a solution of hexafluoroisopropanol (hereinafter sometimes referred to as HFIP) / chloroform = 1/1.
It was left to dissolve for 6 hours, and filtered (diameter: filtration surface diameter: 14 mm) with a membrane filter having an opening of 1 μm. Further on the filter paper surface
After sufficient washing with HFIP, the sample was air-dried, and the number of colored foreign substances (3 μ or more) on the entire filter paper surface was counted with an optical microscope (200 ×) to evaluate the degree of foreign substances.

5) Analysis of foreign metal components: The surface of the filter paper obtained in 4) was spread as widely as possible for the purpose of detecting metal components, and was then spread with an electron microscope (S-570).
Hitachi) XM the filter paper surface (2mm x 2.2mm) at 50x magnification.
A analysis (Québex 8000 Québex) was performed. Three or more XMA analyzes were performed on one filter paper sample, and the average was taken as the metal component of the foreign matter.

6) Evaluation of Polymer Filtration The polymer dried at 160 ° C. for 6 hours was melted with a uniaxial ruder set at a melting temperature of 295 ° C., and passed through a stainless steel filter of 1000 mesh at a discharge rate of 25 g / min and a spinneret of 36 holes. Spinning was performed at a spinning temperature of 300 ° C. The pack pressure was measured every 30 minutes after the chip was supplied to the ruder until the pack pressure applied to the filter became stable (1 hour), and the pack pressure was measured every 30 minutes, and the rate of pressure increase per unit time was measured.

7) Spinnability The polymer dried at 160 ° C. for 6 hours has a diameter of 295 ° C. at a melting temperature of 295 ° C.
31g output from spinneret with 26 0.3mm spinning nozzles
/ min, spinning speed 5500m / min, polyester about 2
T was melt-spun, and the number of yarn breaks during spinning and the number of broken single fibers (fuzz) of the obtained polyester fiber were examined. The number of times of thread breakage during spinning is expressed as the number of times of thread breakage per 1 T of polyester discharge amount. In addition, the number of fluffs is calculated by counting the number of fluffs of polyester fiber by the photoelectric tube method and the number of fluffs per 1 million m.

Examples 1 and 2, Comparative Examples 1 to 4 3600 parts of terephthalic acid and 2750 parts of ethylene glycol were slurried at room temperature, charged into an autoclave equipped with a stirrer, and heated at 270 ° C. under a pressure of 3 kg / cm ² . Reacted.
When the amount of distilled water reached 600 parts, the pressure was released, and the reaction was further performed at 270 ° C. under normal pressure. When the amount of COOH terminal groups of the oligomer obtained in this manner reached about 200 eq / T, orthophosphoric acid was added, and antimony trioxide / ethylene glycol was added 10 minutes later so that the amount of antimony shown in Table 1 was obtained. Was added as a catalyst. Subsequently, polyethylene terephthalate having an intrinsic viscosity of about 0.645 at 0.1 mmHg was gradually obtained under high vacuum and reduced pressure at 285 ° C. Table 1 shows the quality of the polymer, and Table 2 shows the number of black foreign substances and the metal components of the foreign substances. Table 3 shows the spinnability of this polymer.
Shown in

Comparative Example 5 A polyethylene terephthalate having an intrinsic viscosity of 0.640 was obtained in the same manner as in Example 1 except that trimethyl phosphate was added instead of orthophosphoric acid. Table 1 shows the quality of the polymer, and Table 2 shows the number of black foreign substances and the metal components of the foreign substances. Table 3 shows the spinnability of this polymer.

Comparative Example 6 Polyethylene terephthalate having an intrinsic viscosity of 0.640 was obtained in the same manner as in Example 1 except that trimethyl phosphate was added instead of orthophosphoric acid.
Table 1 shows the quality of the polymer, and Table 2 shows the number of black foreign substances and the metal components of the foreign substances. Table 3 shows the spinnability of this polymer.

Examples 3 and 4, Comparative Examples 7 to 10 3600 parts of terephthalic acid and 2100 parts of ethylene glycol were slurried at room temperature and charged in an autoclave equipped with a stirrer.
The reaction was performed at 270 ° C. under a pressure of g / cm ² . When the volume of distillate reaches 600 parts, the pressure is released, and the pressure is reduced to 270 ° C at normal pressure.
Was reacted. Further, when the amount of distilled water reached 740 parts, 0.21 part of orthophosphoric acid was added, and 10 minutes later, 1.58 parts of antimony trioxide as a clear solution of antimony trioxide / ethylene glycol was added to synthesize an oligomer. Half the amount of this oligomer was removed from the system, the temperature of the remaining oligomer was lowered to 255 ° C, and the tube was held for 10 minutes. Was added into the oligomer at a speed of 18.5 parts / min over 100 minutes. afterwards,
The esterification reaction was allowed to proceed for 120 minutes while maintaining the internal temperature at 255 ° C. Table 1 shows the amount of COOH terminal groups of the oligomers in the system at this time. Next, orthophosphoric acid was added to the oligomer, and 10 minutes later, a clear solution of antimony trioxide / ethylene glycol was added as a catalyst. The amount added at this time is the amount of the catalyst remaining in the polyester as shown in Table 1. Subsequently, after stirring for 10 minutes, half of the oligomer was taken out to another system and gradually reduced under high vacuum at 285 ° C. to obtain polyethylene terephthalate having an intrinsic viscosity of about 0.645 at 0.1 mmHg. Table 1 shows the quality of the polymer, and Table 2 shows the number of black foreign substances and the metal components of the foreign substances. Table 3 shows the spinnability of this polymer.

[0038] [Comparative Example 11] and 3600 parts of terephthalic acid and ethylene glycol 2100 parts slurried at room temperature, charged into an autoclave fitted with a stirrer, pressure 2 of 3 kg / cm ²
The reaction was performed at 70 ° C. The pressure was released when the amount of distilled water reached 600 parts, and the reaction was further performed at 270 ° C. under normal pressure. Further, when the amount of distilled water reached 740 parts, 0.30 part of trimethyl phosphate was added, and 10 minutes later, 1.58 parts of antimony trioxide was added as a transparent solution of antimony trioxide / ethylene glycol to synthesize an oligomer. Half of this oligomer was removed from the system, and the temperature of the remaining oligomer was reduced to 25%.
After lowering the temperature to 5 ° C. and holding for 10 minutes, 1800 parts of terephthalic acid / ethylene glycol 10 previously prepared in another container
50 parts of the slurry were added at a rate of 18.5 parts / min into the oligomer over 100 minutes. Then, the internal temperature is 255 ℃
And the esterification reaction was allowed to proceed for 120 minutes.
Table 1 shows the amount of COOH terminal groups of the oligomers in the system at this time. Next, trimethyl phosphate was added to the oligomer, and 10 minutes later, a clear solution of antimony trioxide / ethylene glycol was added as a catalyst. The addition amount is the amount shown in Table 1 in which the catalyst remains in the polymer. After continuous stirring for 10 minutes, half of the oligomer was taken out to another system and gradually reduced to a high vacuum at 285 ° C. under a reduced pressure.
Polyethylene terephthalate having an intrinsic viscosity of 0.639 at 1 mmHg was obtained. Table 1 shows the quality of the polymer, and Table 2 shows the number of black foreign substances and the metal components of the foreign substances. Table 3 shows the spinnability of this polymer.

[0039] [Comparative Example 12] and 3600 parts of terephthalic acid and ethylene glycol 2100 parts slurried at room temperature, charged into an autoclave fitted with a stirrer, pressure 2 of 3 kg / cm ²
The reaction was performed at 70 ° C. The pressure was released when the amount of distilled water reached 600 parts, and the reaction was further performed at 270 ° C. under normal pressure. Further, when the amount of distilled water reached 740 parts, 0.21 part of orthophosphoric acid was added, and 10 minutes later, 1.58 parts of antimony trioxide was added as a transparent solution of antimony trioxide / ethylene glycol to synthesize an oligomer. Half of this oligomer was removed from the system, the temperature of the remaining oligomer was lowered to 255 ° C and held for 10 minutes, and then a slurry of 1800 parts of terephthalic acid / 1050 parts of ethylene glycol prepared in another container in advance Was added into the oligomer at a speed of 18.5 parts / min over 100 minutes. Thereafter, the esterification reaction was allowed to proceed for 120 minutes while maintaining the internal temperature at 255 ° C. Table 1 shows the amount of COOH terminal groups of the oligomers in the system at this time. Next, orthophosphoric acid was added to the oligomer, and 10 minutes later, a clear solution of antimony trioxide / ethylene glycol was added as a catalyst. The amount added at this time is the amount of the catalyst remaining in the polymer as shown in Table 1. Subsequently, after stirring for 10 minutes, half of the oligomer was taken out to another system and gradually reduced under high vacuum at 285 ° C. for 0.1 mm.
Polyethylene terephthalate having an intrinsic viscosity of 0.643 in Hg was obtained. Table 1 shows the quality of the polymer, and Table 2 shows the number of black foreign substances and the metal components of the foreign substances. Table 3 shows the spinnability of this polymer.

[0040]

[Table 1]

[0041]

[Table 2]

[0042]

[Table 3]

[0043]

According to the present invention, the amount of black foreign substances generated in a polymer can be reduced while using an Sb compound as a polycondensation catalyst.

Claims (6)

[Claims] 1. An aromatic polyester produced from an aromatic dicarboxylic acid and a glycol or a lower alkyl ester of an aromatic dicarboxylic acid and a glycol using a Sb compound as a polymerization catalyst and orthophosphoric acid as a stabilizer, An aromatic polyester in which the remaining amount of the compound and orthophosphoric acid in the entire polyester satisfies the following formulas (1) and (2). 50 ≦ Sb ≦ 500 (1) 0.5 ≦ P ≦ 70 (2) (Sb and P are residual concentrations of each element in polymer (ppm)) 2. The aromatic polyester according to claim 1, wherein the amount of COOH terminal groups of the oligomer immediately before adding the Sb compound and / or orthophosphoric acid is 350 eq / T or less. 3. A method for producing an aromatic polyester, which comprises producing an aromatic dicarboxylic acid and a glycol or a lower alkyl ester of an aromatic dicarboxylic acid and a glycol using a Sb compound as a polymerization catalyst and orthophosphoric acid as a stabilizer. The time when the Sb compound and / or orthophosphoric acid is added to the reaction system at a time when the COOH terminal group amount of the intermediate oligomer is 350 eq / T or less, and the time when the orthophosphoric acid is added is the same as the time when the Sb compound is added or A method for producing an aromatic polyester, wherein the time is within 15 minutes before and after the time of adding the Sb compound. 4. The method for producing an aromatic polyester according to claim 3, wherein the aromatic polyester is the aromatic polyester according to claim 1. 5. The fragrance according to claim 3, wherein the reaction is a Bx-type direct heavy reaction method in which one or more reaction tanks are used as the esterification reaction tank and one or more reaction tanks are used as the polymerization reaction tank. For producing aromatic polyesters. 6. The fragrance according to claim 3, which is a Bx-type transesterification reaction wherein one or more reaction tanks are used as transesterification reaction tanks and one or more reaction tanks are used as polymerization reaction tanks. For producing aromatic polyesters.