JP5911734B2 - Polyester resin composition and method for producing the same - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a polyester resin composition and a method for producing the same, and more particularly to a polyester resin composition suitable for film use having excellent color tone and excellent electrostatic adhesion and a method for producing the same.

  Conventionally, polyester resins, particularly polyethylene terephthalate (hereinafter referred to as PET), have been used for films, fibers, sheets, bottles and the like because of their excellent mechanical properties, heat resistance, chemical resistance, hygiene, and the like. PET is produced by a polycondensation reaction between terephthalic acid or an ester-forming derivative thereof and ethylene glycol. Antimony compounds, germanium compounds, and the like are widely used as polycondensation catalysts at that time.

  In PET for bottles, although germanium dioxide is used as a polycondensation catalyst, it is rare and expensive, and an alternative has been desired. Moreover, in PET for film use and fiber use, although antimony trioxide is used as a polycondensation catalyst, the amount of elution in food use is regulated, so the development of alternative products has been desired. In recent years, it has been proposed to use a titanium compound as a polycondensation catalyst for PET as an alternative to a germanium compound or an antimony compound (see, for example, Patent Documents 1 and 2). However, since the catalytic activity of the titanium compound is very strong, the color tone of the resulting resin has deteriorated when the polymer residence time and the polycondensation time are long.

  Further, a polycondensation catalyst of a polyester resin using a phosphorus-containing zirconium multinuclear complex as a zirconium compound has been proposed (see Patent Document 3). However, in this phosphorus-containing zirconium multinuclear complex, the zirconium raw material for forming the polynuclear complex is expensive, and the production conditions for the polynuclear complex are very complicated, such as the reaction at a low temperature of −60 ° C. in toluene. Not suitable for mass production. Moreover, since this polynuclear complex has too high activity as a catalyst, the color tone of the resulting resin tends to deteriorate.

  On the other hand, when PET is used for a film, a magnesium compound is usually added as a pinning agent (electrostatic adhesive) for the purpose of increasing electrostatic adhesion and increasing production efficiency. Here, when a conventional polycondensation catalyst is used, there is a problem that the color tone of the PET film deteriorates due to the addition of a magnesium compound as a pinning agent, and high productivity due to excellent electrostatic adhesion, There has been a demand for the development of PET having a good color tone.

Japanese Patent Laid-Open No. 2001-200046 JP 2001-200044 A JP 2005-36059 A

  The present invention has been made for the purpose of solving the problems of the prior art. That is, the problem to be solved by the present invention is a polyester resin composition having excellent electrostatic adhesion and good color tone and its It is to provide a manufacturing method.

  As a result of intensive studies to solve the above problems, the present inventors have added a specific amount of a magnesium compound as an electrostatic adhesion agent and a specific zirconium compound as a polycondensation catalyst in the polycondensation reaction of the polyester resin. It is excellent in electrostatic adhesion by adjusting the ratio of magnesium element content and zirconium element and phosphorus element content in the polycondensation reaction system to be in a specific range using the reaction product of phosphorus and phosphorus compound In addition, the inventors have found that a polyester resin composition having a good color tone can be obtained, and have completed the present invention.

That is, the polyester resin composition according to the present invention comprises (A) a polyester resin whose main repeating unit is ethylene terephthalate, (B) a magnesium compound of 50 to 150 ppm in terms of magnesium element metal, and (C) a monoalkyl phosphate. It contains a reaction product of an ester and a zirconium alkoxide, and the magnesium element content, zirconium content and phosphorus element content in the composition satisfy the following mathematical formulas (i) and (ii).
5 ≦ Mg / Zr ≦ 10 (i)
Mg: Magnesium element metal equivalent (mol / kg)
Zr: zirconium element metal equivalent (mol / kg)
1.5 ≦ Mg / P ≦ 3.5 (ii)
Mg: Magnesium element metal equivalent (mol / kg)
P: Phosphorus element metal equivalent (mol / kg)

（式中、Ｒ^１は炭素数１〜１０のアルキル基である。）
また、本発明にかかるポリエステル樹脂組成物において、３００℃における溶融電気伝導度が２０〜１５０ｎＳ／ｃｍであることが好適である。 In the polyester resin composition according to the present invention, it is preferable that the reaction product of the (C) phosphoric acid monoalkyl ester and the zirconium alkoxide is a compound represented by the following general formula (1).

(In the formula, R ¹ is an alkyl group having 1 to 10 carbon atoms.)
In the polyester resin composition according to the present invention, it is preferable that the melt electrical conductivity at 300 ° C. is 20 to 150 nS / cm.

  Moreover, the manufacturing method of the polyester resin composition concerning this invention is (B) magnesium element metal with respect to (A1) dicarboxylic acid component which has terephthalic acid as a main component, and (A2) diol component which has ethylene glycol as a main component. The magnesium compound content in the polycondensation reaction system, the zirconium content and the phosphorus element content are added by adding 50 to 150 ppm in terms of magnesium compound and (C) a reaction product of a monoalkyl phosphate and zirconium alkoxide. It comprises a step of performing a polycondensation reaction under conditions that satisfy (i) and (ii).

  According to the present invention, in the polycondensation reaction of a polyester resin, a specific amount of a magnesium compound is added as an electrostatic adhesion agent, a reaction product of a specific zirconium compound and a phosphorus compound is used as a polycondensation catalyst, and polycondensation is performed. By adjusting the ratio of the magnesium element content and the zirconium element and phosphorus element contents in the reaction system to be in a specific range, a polyester resin composition having excellent electrostatic adhesion and good color tone can be obtained.

Hereinafter, the present invention will be described in more detail.
The polyester resin composition according to the present invention comprises (A) a polyester resin whose main repeating unit is ethylene terephthalate, (B) a magnesium compound of 50 to 150 ppm in terms of magnesium element metal, and (C) a monoalkyl phosphate. It contains a reaction product with zirconium alkoxide.

(A) Polyester resin (A) The polyester resin contained in the polyester resin composition of the present invention is composed of ethylene terephthalate as a main repeating unit, and a dicarboxylic acid component mainly composed of terephthalic acid and ethylene glycol. It can be obtained by performing a polycondensation reaction after esterification or transesterification with a diol component as a main component.

  (A) The dicarboxylic acid component of the polyester resin contains terephthalic acid units in an amount of 90 mol% or more, more preferably 95 mol% or more. The total amount of the dicarboxylic acid component may be terephthalic acid units. Specific examples of dicarboxylic acid components other than terephthalic acid include isophthalic acid, phthalic acid, 2,6-naphthalenedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, sodium sulfoisophthalate, succinic acid, adipic acid, and sebacic acid. And azelaic acid. These copolymer components may be used in an amount of 10 mol% or less, more preferably 5 mol% or less.

  The diol acid component of the (A) polyester resin may contain 90% by mole or more, more preferably 95% by mole or more of ethylene glycol units, and the total amount of diol components may be ethylene glycol units. Specific examples of diol components other than ethylene glycol include diethylene glycol, neopentyl glycol, 1,4-cyclohexanedimethanol, propylene glycol, 1,4-butanediol, 1,2-butanediol, and the like. The copolymer component may be used in an amount of 10 mol% or less, more preferably 5 mol% or less.

  The polyester resin composition according to the present invention is an electrostatic adhesion agent comprising (A1) a dicarboxylic component mainly composed of terephthalic acid and (A2) a diol component mainly composed of ethylene glycol (B It is obtained as a composition containing (A) a polyester resin by polycondensation reaction with a reaction product of a magnesium compound, a polycondensation catalyst (C) phosphoric acid monoalkyl ester and zirconium alkoxide. The polycondensation reaction of the polyester resin is not particularly limited and can be performed by a known method. More specifically, for example, a dicarboxylic component containing terephthalic acid as a main component and a diol component containing ethylene glycol as a main component are charged into a reaction vessel, and the reaction is performed under an atmospheric pressure or relative pressure in an inert gas atmosphere such as nitrogen. The esterification reaction is performed at 230 to 260 ° C. under a pressure of 0.25 MPa or less, and after adding other additives such as an electrostatic adhesion agent, a polycondensation catalyst, or a heat stabilizer, the atmospheric pressure is increased. Gradually depressurize and finally control the absolute pressure to 1.33 to 0.013 kPa, stir the reaction temperature at 265 to 290 ° C. for about 1 to 10 hours, and carry out polycondensation reaction to a predetermined molecular weight. By (A), the composition containing a polyester resin can be obtained.

(B) Magnesium Compound The (B) magnesium compound used in the present invention is added for the purpose of imparting electrostatic adhesion. (B) Examples of the magnesium compound include magnesium metal oxides, hydroxides, acetates, carbonates, and the like, and more specifically, magnesium oxide, magnesium hydroxide, magnesium acetate, and magnesium carbonate. It is done. Among these, magnesium acetate is preferable, and magnesium acetate hydrate is more preferable from the viewpoint of handleability.

  Content of the (B) magnesium compound in the polyester resin composition of this invention is 50-150 ppm in metal atom conversion amount. Within this range, when a film of the polyester resin composition is formed, the electrostatic adhesion due to electrostatic application to the cast roll is good, and production at a high production rate is possible. If it is less than 50 ppm, the melt electrical conductivity of the polyester resin composition is low and the film adhesion is insufficient, so that production at a high production rate is impossible. On the other hand, if it exceeds 150 ppm, the color tone of the resin deteriorates. To do.

(C) Reaction product of phosphoric acid monoalkyl ester and zirconium alkoxide The reaction product of (C) used in the present invention is obtained by reacting phosphoric acid monoalkyl ester and zirconium alkoxide. And added as a polycondensation catalyst for polyester resin. Phosphoric acid monoalkyl ester is a phosphoric acid ester in which an alkyl group having 1 to 10 carbon atoms is substituted per molecule, and examples thereof include monomethyl phosphate, monoethyl phosphate, monobutyl phosphate, monoisodecyl phosphate and the like. However, monobutyl phosphate is particularly preferred from the viewpoint of polymerization reaction activity. Here, (C) the reaction product is a mononuclear complex of zirconium metal and has a phosphate ester group at the terminal, so that the catalytic activity is moderate, the polymerization reactivity is excellent, and The color tone of the resin obtained is also good.

  The zirconium alkoxide is a zirconium compound having an alkoxy group having 1 to 10 carbon atoms, such as tetra-n-butoxyzirconium, tetra-n-propoxyzirconium, tributoxy monoacetonatozirconium, tributoxymonoacetonatozirconium. In particular, tetra-n-butoxyzirconium and tetra-n-propoxyzirconium are preferable.

  In addition, when zirconium alkoxide is added to the reaction system alone as a polycondensation catalyst, the hydrolysis rate is very fast. For example, when pre-prepared as an ethylene glycol dispersion or when pre-prepared in pure water Since the hydrolysis reaction proceeds in the preparation stage, a precipitate of zirconium dioxide is formed and the catalytic activity is lost. Further, even when added directly to the polycondensation reaction system, the hydrolysis reaction proceeds in the polymerization system, and not only the catalytic activity function is lost, but also white precipitates due to zirconium dioxide are precipitated in the polyester resin. .

（式中、Ｒ^１は炭素数１〜１０のアルキル基である。） In the present invention, the phosphoric acid monoalkyl ester and the zirconium alkoxide may be simultaneously added to the polycondensation reaction system, but the reaction product is prepared in advance from the viewpoint of the hydrolysis reaction of the zirconium alkoxide described above. In addition, it is desirable to add to the polycondensation reaction system. The reaction product of (C) phosphoric acid monoalkyl ester and zirconium alkoxide used in the present invention includes a compound (zirconium-monoalkyl phosphoric acid complex) represented by the following general formula (1).

(In the formula, R ¹ is an alkyl group having 1 to 10 carbon atoms.)

(C) The reaction product of phosphoric acid monoalkyl ester and zirconium alkoxide is preferably prepared, for example, by the following method from the viewpoint of suppressing the hydrolysis rate of zirconium alkoxide.
(1) In a reactor equipped with a fractionating tube and a condenser tube, the monoalkyl ester phosphate is dissolved in an excess solvent and stirred (solution A). As the solvent, an alcohol such as ethanol or methanol is preferable. The solution needs to be stirred in an inert atmosphere such as nitrogen.
(2) Separately from solution A, zirconium alkoxide is stirred and dissolved in an excess solvent (alcohol, etc.) together with a small amount of acid such as acetic acid or citric acid (solution B).
(3) While the solution B is added dropwise to the solution A being stirred in an inert atmosphere, the stirring is continued at 50 to 90 ° C., preferably 60 to 80 ° C. When the solution B is added dropwise, the reaction of the monoalkyl phosphate ester in the solution A and the zirconium alkoxide in the solution B proceeds, and a cloudy solution C is formed.
(4) An excessive amount of ethylene glycol is dropped into the solution C, followed by stirring.
(5) The internal temperature of the reaction system is controlled to 80 to 200 ° C., preferably 100 to 150 ° C., stirred for 30 minutes to 2 hours to evaporate a solvent such as ethanol, and aggregated and collected in a cooling tube. Although it is possible to carry out under atmospheric pressure, it is more preferred to carry out under reduced pressure because of the quick distillation of the solvent.
(6) When the predetermined amount of solvent is distilled off, the reaction system is cooled to room temperature to obtain an ethylene glycol dispersion of the reaction product of zirconium alkoxide and phosphoric acid monoalkyl ester.

  (C) As for the setting compounding quantity at the time of preparation of the reaction product of phosphoric acid monoalkyl ester and zirconium alkoxide, the ratio of molar amount in terms of zirconium element and molar amount in terms of phosphorus element is 1/1 to 1/3. Is preferable, and more preferably 1/1 to 1/2. Moreover, the said (C) reaction product obtained by the above method is obtained as an ethylene glycol dispersion liquid. This ethylene glycol dispersion can be subjected to reduced pressure filtration, pressure filtration, centrifugal sedimentation, etc., and (C) only the reaction product can be separated and extracted and used as a polycondensation catalyst. A) Since the main diol component of the polyester resin is ethylene glycol, it is easier to add it as an ethylene glycol dispersion.

Magnesium element content, zirconium content and phosphorus element content in the composition In addition, in the polyester resin composition according to the present invention, the moles of zirconium element content (metal equivalent) and magnesium element content (metal equivalent) per kg of the composition. The ratio needs to satisfy the following formula (i).
5 ≦ Mg / Zr ≦ 10 (i)
Mg: Magnesium element metal equivalent (mol / kg)
Zr: zirconium element metal equivalent (mol / kg)
When the ratio of the zirconium element content and the magnesium element content deviates from the above range, the polymerization reaction rate is lowered. On the other hand, if it is in the said range, the polymerization rate comparable as the case where the conventional polyester polycondensation catalyst (for example, antimony trioxide) is used can be achieved.

  In addition, in the polyester resin composition concerning this invention, it is possible to contain the phosphorus element compound as a heat stabilizer other than the phosphoric acid monoalkyl ester used for the said (C) reaction product. Phosphorus element compounds as heat stabilizers include, for example, pentavalent phosphate compounds such as orthophosphoric acid, trimethyl phosphate, triethyl phosphate, and trioctyl phosphate, trivalent phosphorus such as phosphorous acid, trimethyl phosphite, and triethyl phosphite. Among them, pentavalent trimethyl phosphate and triethyl phosphate are particularly preferable.

When a phosphorus element compound as a heat stabilizer is added, the phosphorus element content derived from the monoalkyl phosphate phosphate used in the (C) reaction product as the polycondensation catalyst and the phosphorus element compound as a heat stabilizer The phosphorus element content is a molar ratio between the total phosphorus element content (metal equivalent) and magnesium element content (metal equivalent) contained in the composition, although it cannot be separated in the composition. However, it is necessary to satisfy the following general formula (ii).
1.5 ≦ Mg / P ≦ 3.5 (ii)
Mg: Magnesium element metal equivalent (mol / kg)
P: Phosphorus element metal equivalent (mol / kg)
When the ratio of the phosphorus element content to the magnesium element content is less than 1.5, the electrical conductivity at the time of melting of the polyester resin composition is lowered, and the cast roll adhesion at the time of film formation is deteriorated. On the other hand, when it exceeds 3.5, the color tone of the polyester resin composition deteriorates.

  In the present invention, the (B) magnesium compound as the additive, the (C) reaction product as the polycondensation catalyst, and the phosphorus element compound as the heat stabilizer are added in any of the polycondensation reaction steps of the polyester resin. However, from the viewpoint of stability, it is desirable to add the dicarboxylic acid component and the diol component immediately before the completion of the esterification reaction and the start of the polycondensation reaction. In addition, it is desirable to add them to the reaction system in the state of an ethylene glycol dispersion.

  In the polyester resin composition according to the present invention, the melt electrical conductivity when melted at 300 ° C. is preferably 20 to 150 nS / cm, more preferably 25 to 80 nS / cm. When it is less than 20 nS / cm, the electrostatic adhesion in the cast roll (cooling roll) during film formation is poor, and it is necessary to reduce the film formation rate, resulting in a decrease in production efficiency. If it exceeds 150 nS / cm, even if a voltage is applied to give static electricity, the generated current value is high, that is, an energization phenomenon occurs, and the charge on the film surface is lowered, so that the adhesion is also lowered. Moreover, since the color tone is bad and the value as a product falls, the polyester resin in the case of exceeding 150 nS / scm is not preferable.

  In addition, in the polyester resin composition according to the present invention, inert particles having an average particle size of 0.05 to 5.0 μm may be appropriately added as an additive other than the above as an anti-blocking agent during film formation. it can. Examples of these particles include silica, titania, alumina, calcium carbonate, barium sulfate and the like.

  Moreover, in the polyester resin composition concerning this invention, you may add coloring agents, such as a metal salt and dye, in order to further improve a color tone. Examples of the metal salt include cobalt acetate hydrate, and examples of the dye include azo, anthraquinone, phthalocyanine, quinone, and triphenylmethane. Among these, it is preferable to use an anthraquinone blue dye in combination for the purpose of adjusting the yellow color of the resin. The dye may be appropriately blended according to the target color tone, but is preferably about 0.5 to 7 ppm with respect to the polyester resin composition. Furthermore, an antioxidant, an antistatic agent, an ultraviolet ray inhibitor, a light stabilizer, and the like can be added as necessary.

  Hereinafter, the present invention will be described in more detail with reference to examples. In addition, the various characteristic values in the following Examples and Comparative Examples are evaluated by the following methods.

(1) Intrinsic viscosity (IV)
An automatic viscosity measuring apparatus (ALC-6C manufactured by Sun Electronics Co., Ltd.) equipped with an Ubbelohde viscosity tube, in which the polyester resin compositions of various examples and comparative examples were dissolved in a mixed solvent of phenol / tetrachloroethane = 60/40 (weight ratio). ) Was used to measure the solution viscosity (dl / g) at 20 ° C.
(2) Color tone (color L value, b value)
The pellets of the polyester resin compositions of various examples and comparative examples were put into dedicated cells, and the Hunter L value and b value were measured with a color difference meter (Nippon Denshoku ZE-2000). For the b value, the pass / fail judgment of the color tone was performed according to the following criteria.
◎ b value ≤ 8.0
○ 8.0 <b value ≦ 10.0
X b value> 10.0

(3) Amount of metal element in resin composition 1.0 g of polyester resin compositions of various examples and comparative examples were heated and incinerated with sulfuric acid and nitric acid, and an ICP emission analyzer (SPS 1500VR, manufactured by SII Corporation). The metal element content was measured in ppm.
(4) Melt electrical conductivity Polyester resin compositions of various examples and comparative examples were vacuum dried at 150 ° C. for 5 hours, then put into a dedicated test tube and immersed in a salt bath with a heating medium of 300 ° C. in a nitrogen atmosphere. After melting for 20 minutes, a dedicated electrode is inserted, a constant voltage of 85 V is applied to the molten resin for 1 minute, and the current value 1 second after the start of application is measured. From the electrode surface thickness of the molten resin and the effective area of the electrode part The melt electrical conductivity was calculated from the following formula, and the unit was expressed in nS / cm.
Melt electric conductivity = (current value × electrode surface thickness) / (applied voltage × electrode area effective area)

(5) Polymerization time The polymerization time of the polyester resin compositions of various examples and comparative examples is defined as the time from the start of the polycondensation reaction until the stirring torque of the stirrer reaches a predetermined value. Based on the polycondensation time of 180 to 220 minutes when a catalyst (antimony trioxide) was used, the following evaluation criteria were used.
◎ Less than 220 minutes ○ More than 220 minutes and less than 250 minutes × More than 250 minutes

Preparation Example 1: (C) Reaction Product Dispersion (1) Preparation of Liquid A A 100 mL Erlenmeyer flask equipped with a reflux tube was charged with 20.15 g of ethanol and 4.03 g (26 mmol) of monobutyl phosphate with a stirrer. While stirring, the mixture was stirred at 70 ° C. for 10 minutes to obtain a liquid A.
(2) Preparation of solution B To a 100 mL three-necked flask equipped with a nitrogen introduction tube and an exhaust tube, 25 g of ethanol and 0.5 g (0.83 mmol) of acetic acid were added and stirred for 10 minutes under a trace nitrogen flow. Thereafter, 5 g (13 mmol) of tetra-n-butoxyzirconium was gradually added dropwise while continuing stirring of the ethanol-acetic acid solution, and stirred for 10 minutes to obtain a solution B.
(3) Reaction Stirring A liquid at 70 degreeC, adding B liquid, making it react at 70 degreeC under reflux for 1 hour, and (C) ethanol dispersion of the reaction product of monobutyl phosphate and tetra-n-butoxyzirconium A liquid was obtained.
(4) Solvent replacement The ethanol solution of the reaction product (C) obtained in (3) was charged into a 1 L three-necked flask equipped with a nitrogen collector and a moisture collector equipped with a reflux tube at the top. 442.4 g of glycol was added and ethanol was distilled off in an oil bath heated to 100 ° C. while flowing a trace amount of nitrogen to obtain (C) a pale white ethylene glycol dispersion liquid in which the reaction product was dispersed.

Example 1
The theoretical scale of the polyester resin composition is 10 kg, 6.56 kg of bishydroxyethylene terephthalate (BHET), 4.29 kg of terephthalic acid (TPA), and 0.49 kg of ethylene glycol are charged into a 30 L autoclave equipped with a rectifying column, and nitrogen flow The esterification reaction is performed while raising the internal temperature to 250 ° C. under the atmospheric pressure, and the water distilled by the reaction is fractionated, and a predetermined amount is removed from the system, and the esterification reaction is carried out to an esterification rate of 95% or more. went. Thereafter, (B) 80 ppm of an ethylene glycol solution of magnesium acetate tetrahydrate was added as magnesium element and stirred, and then (C) monobutyl phosphate and tetra- obtained in Preparation Example 1 were used as a polycondensation catalyst. An ethylene glycol dispersion of the reaction product of n-butoxyzirconium was added in an amount of 50 ppm as the zirconium element (35 ppm as the phosphorus element) and stirred. Subsequently, while raising the internal temperature to 280 ° C., the pressure in the system is reduced to 13.3 kPa or less in 1 hour, and a polycondensation reaction is performed to a predetermined viscosity under a high vacuum of 13.3 kPa or less. A polyester resin composition pellet was obtained by cutting with a pelletizer. Various physical properties of the obtained polyester resin composition are as shown in Table 1.

Examples 2 and 3
(B) Magnesium acetate tetrahydrate and (C) the addition amount of the reaction product of monobutyl phosphate and tetra-n-butoxyzirconium, the Mg content, Mg / Zr ratio and Mg / P ratio shown in Table 1 The pellets of the polyester resin composition were obtained in the same manner as in Example 1 except that the change was made. Various physical properties are as shown in Table 1.

Examples 4-6
After adding triethyl phosphoric acid as a heat stabilizer to 10 ppm (Examples 4 and 5) and 25 ppm (Example 6) as phosphorus element, (B) magnesium acetate tetrahydrate and (C) monobutyl phosphate and tetra- The addition amount of the reaction product of n-butoxyzirconium was changed to the Mg content, Mg / Zr ratio, and Mg / P ratio shown in Table 1, and in the same manner as in Example 1, pellets of the polyester resin composition Got. Various physical properties are as shown in Table 1.

Example 7
(C) A blue dye (RLS manufactured by Clariant Japan Co., Ltd.) was added to the ethylene glycol dispersion of the reaction product of monobutyl phosphate and tetra-n-butoxyzirconium so as to be 2 ppm in the polyester resin composition. Polyester resin composition pellets were obtained in the same manner as in Example 1. Various physical properties are as shown in Table 1.

Comparative Examples 1-6
(B) Magnesium acetate tetrahydrate and (C) the addition amount of the reaction product of monobutyl phosphate and tetra-n-butoxyzirconium, the Mg content, Mg / Zr ratio and Mg / P ratio shown in Table 2 The pellets of the polyester resin composition were obtained in the same manner as in Example 1 except that the change was made. Various physical properties are as shown in Table 2.

Comparative Example 7
In Preparation Example 1, instead of tetra-n-butoxyzirconium, tetra-n-butoxytitanium was used in the same manner as in Example 1 except that tetrabutyl phosphate was used in an amount of 1/2 mol of the monobutyl phosphate charge. Thus, pellets of the polyester resin composition were obtained. Various physical properties are as shown in Table 2.

  As shown in Table 1 above, 50 to 100 ppm of (B) magnesium compound is added, and (C) the reaction product of phosphoric acid monoalkyl ester and zirconium alkoxide has an Mg / Zr ratio of 6.0 to 9.6. In Examples 1 to 7 in which the polycondensation reaction of terephthalic acid and ethylene glycol was carried out by adding so that the Mg / P ratio was in the range of 1.7 to 2.9, good melt electrical conductivity was obtained. And (B) a polyester resin composition having a high transparency (low b value) and excellent color tone can be obtained in a relatively short polymerization time despite containing the magnesium compound (B). I understood.

  On the other hand, as shown in Table 2 above, in Comparative Example 1 where the amount of (B) magnesium compound added was small, the melt electrical conductivity was not sufficiently improved, and the time required for the polymerization also became longer. . Moreover, in the comparative example 2 with much (B) magnesium compound addition amount, the color tone deteriorated. Furthermore, in (C) Comparative Example 3 in which the Mg / Zr ratio was increased by adjusting the Zr content of the reaction product and Comparative Example 4 in which the Mg / Zr ratio was decreased, the time required for the polymerization was increased. .

Further, (C) In Comparative Example 5 in which the Mg / P ratio was increased by adjusting the P content of the reaction product, the color tone deteriorated. On the other hand, in Comparative Example 6 in which the Mg / P ratio was decreased, the molten electrical conduction The degree of polymerization was not sufficient, and the time required for polymerization also became longer. Furthermore, in Comparative Example 7 in which a Ti compound was used in place of the Zr compound in the (C) reaction product used as the polycondensation catalyst, the deterioration in color tone due to the (B) magnesium compound was not improved.

Claims (3)

(A) a polyester resin whose main repeating unit is ethylene terephthalate;
(B) 50-150 ppm magnesium compound in terms of magnesium element metal;
(C) a reaction product of phosphoric acid monoalkyl ester and zirconium alkoxide, the magnesium element content, zirconium content and phosphorus element content in the composition satisfy the following formulas (i) and (ii):

5 ≦ Mg / Zr ≦ 10 (i)
Mg: Magnesium element metal equivalent (mol / kg)
Zr: zirconium element metal equivalent (mol / kg)
1.5 ≦ Mg / P ≦ 3.5 (ii)
Mg: Magnesium element metal equivalent (mol / kg)
P: Phosphorus element metal equivalent (mol / kg)

A polyester resin composition having a resin color tone b value of 4.6 to 8.6 and a melt electric conductivity at 300 ° C. of 33 to 120 nS / cm .
The reaction product of the monoalkyl phosphate ester and zirconium alkoxide is characterized in that the ratio of the molar amount of zirconium element converted to the molar amount of phosphorus element converted at the time of preparation is 1/1 to 1/3. The polyester resin composition according to 1.
For (A1) a dicarboxylic acid component based on terephthalic acid and (A2) a diol component based on ethylene glycol,
(B) 50-150 ppm magnesium compound in terms of magnesium element metal;
(C) adding a reaction product of a phosphoric acid monoalkyl ester and a zirconium alkoxide in which the ratio of the molar amount in terms of zirconium element to the molar amount in terms of phosphorus at the time of preparation is 1/1 to 1/3; A process for producing a polyester resin composition, comprising a step of performing a polycondensation reaction under conditions where the magnesium element content, zirconium content and phosphorus element content of the condensation reaction system satisfy the following mathematical formulas (i) and (ii): .
5 ≦ Mg / Zr ≦ 10 (i)
Mg: Magnesium element metal equivalent (mol / kg)
Zr: zirconium element metal equivalent (mol / kg)
1.5 ≦ Mg / P ≦ 3.5 (ii)
Mg: Magnesium element metal equivalent (mol / kg)
P: Phosphorus element metal equivalent (mol / kg)