JP2015025097A - Polyester resin composition and direct blow molded article made of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester resin composition which does not cause a problem of drawdown or crystallization in direct blow molding and has excellent thermostability, and from which a direct blow molded article having excellent color tone and transparency can be obtained with high productivity.SOLUTION: There is provided a resin composition containing 0.1 to 1.0 mass% of tetrakis[methylene-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]methane in a polyester resin of which 80 mol% or more of an acid component constituting polyester is terephthalic acid, 80 to 98 mol% of a glycol component is ethylene glycol and 2 to 20 mol% is 1,4-cyclohexanedimethanol, and also containing a germanium compound and further containing at least one of an anthraquinone-based blue dye and an anthraquinone-based purple dye of 0.5 to 5 ppm, and having an intrinsic viscosity (IV) of 0.8 to 1.5 and a swell ratio (SW) of 1.2 to 1.4.

Description

  TECHNICAL FIELD The present invention relates to a polyester resin composition containing a specific compound in a polyester resin, which can obtain a direct blow molded article excellent in color tone and transparency with high productivity.

  Polyethylene terephthalate (PET) is excellent in mechanical properties, chemical stability, transparency and the like, is inexpensive, and is widely used as various sheets, films, containers and the like. The growth in the use of hollow containers (bottles) for fruit juice drinks, liquid seasonings, edible oils, liquors, wines, etc. is remarkable. Moreover, since there is little concern about residual monomers and harmful additives in hollow molded articles made of vinyl chloride resin, and hygiene and safety are high, replacement from conventional bottles made of vinyl chloride resin and the like is also progressing.

  In general, when plastic bottles are manufactured, melt-plasticized resin is used as die orifices in terms of ease of molding, high productivity, and relatively low equipment costs such as molding machines and molds. A so-called direct blow molding method is employed in which a cylindrical parison is formed through extrusion, and air is blown into the mold by sandwiching the parison between the molds. In the case of this direct blow molding, it is necessary to avoid that the parison extruded in the molten state is drawn down during the blow molding in order to perform the molding smoothly. Therefore, a high melt viscosity is required for the resin used. Is done. Accordingly, vinyl chloride resins, polyolefin resins, and the like are widely used in direct blow molding as resins having a high melt viscosity.

  In direct blow molded products, replacement of vinyl chloride resin with polyester resin has been studied, but polyester resins generally do not have a high melt viscosity suitable for direct blow molding. For this reason, there is a problem that the extruded parison draws down during blow molding, and blow molding cannot be performed, and crystallization is likely to occur during blow, so whitening occurs even if molding is possible, and transparency is increased. There was a problem of becoming insufficient.

In order to improve transparency, a polyester resin obtained by copolymerizing polyethylene terephthalate with other monomer components has been proposed. This can suppress crystallization, but it cannot increase the melt viscosity by itself. Therefore, a method has been proposed in which the viscosity is increased by means of crosslinking with a trifunctional or higher polyvalent carboxylic acid / polyhydric alcohol to solve the drawdown problem (see, for example, Patent Document 1).
However, when the viscosity is increased by such a cross-linking means, the moldability is improved, but when the amount of polyvalent carboxylic acid or polyhydric alcohol is large, the gel is easily gelled, the heat stability is inferior, and the resulting molding is obtained. There was a problem that the product was inferior in color and transparency.

  Moreover, in order to suppress the color tone of a molded product, a cobalt compound is added to polyester to suppress yellowing. However, the cobalt compound can improve the hue (b value) of the polyester, but foreign matter is precipitated, and the melt heat stability of the resulting polyester is lowered, so that the yellowness is not sufficiently suppressed. was there.

Japanese Patent No. 3173755

  The present invention solves the above-mentioned problems, does not cause problems of whitening due to drawdown or crystallization during direct blow molding, has excellent thermal stability, and has excellent color tone and transparency. It is intended to provide a polyester resin composition that can be obtained with good productivity, and to provide a direct blow molded article comprising the resin composition of the present invention.

The inventor of the present invention has arrived at the present invention as a result of intensive studies to solve the above problems. That is, the gist of the present invention is the following (1) to (2).
(1) In a polyester resin in which 80 mol% or more of the acid component constituting the polyester is terephthalic acid, 2 to 20 mol% of the glycol component is 1,4-cyclohexanedimethanol, and 80 to 98 mol% is ethylene glycol And 0.1 to 1.0% by mass of tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, and the germanium compound as the acid component 1 of the polyester resin. A resin composition containing 5 × 10 ⁻⁵ mol to 3.0 × 10 ⁻⁴ mol per mol, and further containing 0.5 to 5 ppm of at least one of an anthraquinone blue dye and an anthraquinone purple dye, A polyester resin composition having a viscosity (IV) of 0.8 to 1.5 and a swell ratio (SW) of 1.2 to 1.4 .
(2) A direct blow molded article comprising the polyester resin composition according to (1).

The polyester resin composition of the present invention uses a polyester having a specific composition, contains a specific compound, and has an intrinsic viscosity and a swell ratio suitable for direct blow molding. There are sometimes no problems of whitening due to drawdown or crystallization, and the thermal stability is excellent, and a direct blow molded product excellent in color tone and transparency can be obtained with high productivity.
And since the direct blow molded article of this invention is obtained from the polyester resin composition of this invention, it is excellent in color tone and transparency, and can be used for various uses.

Hereinafter, the present invention will be described in detail.
As for the polyester resin in the polyester resin composition of this invention, 80 mol% or more of the acid component which comprises polyester is a terephthalic acid, 2-20 mol% of a glycol component is 1, 4- cyclohexane dimethanol, 80-98 mol. % Must be ethylene glycol. That is, terephthalic acid and ethylene glycol are the main components and 1,4-cyclohexanedimethanol is the copolymer component. The proportion of 1,4-cyclohexanedimethanol is preferably 3 to 18 mol%, more preferably 4 to 15 mol%. By copolymerizing 1,4-cyclohexanedimethanol, the crystallization speed of the polyester resin can be adjusted to those suitable for direct blow molding, and whitening due to crystallization during direct blow molding can be prevented.

  When the proportion of 1,4-cyclohexanedimethanol in the glycol component is less than 2 mol%, the resin composition has a high crystallization rate. And becomes inferior in transparency. On the other hand, when the proportion of 1,4-cyclohexanedimethanol exceeds 20 mol%, the resin composition becomes amorphous, so that drying at a high temperature and solid phase polymerization are likely to be difficult, or during high temperature drying. In addition, blocking tends to occur in the solid phase polymerization process.

  The proportion of ethylene glycol in the glycol component is from 80 mol% to 98 mol%, and among them, 85 mol% to 90 mol% of the glycol component is preferably ethylene glycol. When the proportion of ethylene glycol is less than 80 mol%, the crystallinity of the resin composition is lowered and it tends to be amorphous. On the other hand, when the proportion of ethylene glycol exceeds 98 mol%, the amount of 1,4-cyclohexanedimethanol copolymerization decreases, making it difficult to adjust the crystallization speed, and whitening due to crystallization during blow molding is difficult. The effect to prevent is poor.

  Examples of glycol components other than ethylene glycol and 1,4-cyclohexanedimethanol include neopentyl glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexamethylenediol, diethylene glycol, dimer diol, An ethylene oxide adduct of bisphenol A or bisphenol S can be used.

  On the other hand, 80 mol% or more of the acid component of the polyester resin is terephthalic acid, and among them, 85 mol% or more of the acid component is preferably terephthalic acid. Examples of the acid component other than terephthalic acid include isophthalic acid, phthalic acid, phthalic anhydride, naphthalenedicarboxylic acid, adipic acid, 1,4-cyclohexanedicarboxylic acid, sebacic acid, dimer acid, and the like. These acids may be used in combination, or ester-forming derivatives of these acids may be used.

  If the ratio of the terephthalic acid as the acid component is less than 80 mol%, the crystallinity of the resin composition is lowered and it is likely to become amorphous, which is not preferable.

The resin composition of the present invention contains 0.1 to 1 tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane in the polyester resin as described above. 0.0% by mass, and 0.2 to 0.8% by mass is particularly preferable.
Tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane is preferably added during the polymerization reaction step of the polyester resin. By adding it during the polymerization reaction step, a part of the compound is copolymerized in the polyester resin. As a result, entanglement of molecular chains occurs in the polyester resin, and it is assumed that a state similar to cross-linking occurs, and the melt viscosity of the polyester resin increases and the swell ratio (SW) satisfies the range defined in the present invention. To be.

  Further, by containing tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane in the resin composition of the present invention, the thermal stability of the resin composition is improved. The resulting molded product is improved in color tone and transparency.

  When the content of tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane is less than 0.1% by mass, the resin composition in which the molecular chain is entangled as described above. Therefore, the swell ratio of the resin composition is low, and the parison draw-down during direct blow molding cannot be prevented. It also becomes difficult to increase the melt viscosity of the resin composition. Furthermore, the thermal stability of the resin composition is not improved, and the resulting molded product is inferior in heat resistance, color tone and transparency.

  On the other hand, if the content exceeds 1.0% by mass, the swell ratio of the resin composition increases, the expansion of the resin composition at the exit of the extrusion die during molding becomes too large, and the surface of the resulting molded product becomes rough. The glossiness is impaired. Further, the melt viscosity of the resin composition becomes too high, and it is necessary to increase the molding temperature during molding, resulting in poor color tone of the molded product. Furthermore, the effect of improving the thermal stability is saturated and disadvantageous in terms of cost.

Next, in the polyester resin composition of the present invention, the germanium compound is contained in an amount of 5 × 10 ⁻⁵ mol to 3.0 × 10 ⁻⁴ mol with respect to 1 mol of the acid component of the polyester resin. It is preferable that 10 < ^-5 > mol-2.0 * 10 < ^-4 > mol is contained.
The germanium compound is used as a polymerization catalyst when obtaining a polyester resin, and if the content of the germanium compound is less than 5 × 10 ⁻⁵ mol, a polyester resin having a target degree of polymerization cannot be obtained, or In the polymerization reaction, the polymerization time becomes longer, and as a result, the color tone of the resulting polyester resin is deteriorated. On the other hand, even if it exceeds 3.0 × 10 ⁻⁴ mol, the effect as a polymerization catalyst is saturated and disadvantageous in cost.

  Examples of the germanium compound include germanium dioxide, germanium tetrachloride, germanium tetraethoxide, and the like, and germanium dioxide is preferred from the viewpoint of polymerization catalyst activity, physical properties of the resulting polyester resin, and cost.

Furthermore, the polyester resin composition of the present invention further contains 0.5 to 5 ppm of at least one of an anthraquinone blue dye and an anthraquinone purple dye, and preferably 1 to 3 ppm. By containing an anthraquinone blue dye and / or an anthraquinone purple dye, a resin composition having a better color tone can be obtained, and a direct blow molded product having a better color tone can be obtained. As an index indicating that the color tone is excellent, the hue (b value) of the polyester resin composition is preferably 1.0 or less, more preferably -0.1 or less.
When the content of the anthraquinone blue dye and / or anthraquinone purple dye is less than 0.5 ppm, the effect of improving the color tone of the polyester resin composition is small. On the other hand, when the content exceeds 5 ppm, the transparency of the polyester deteriorates. It is not preferable.

  As an anthraquinone blue dye, SOLVENT BLUE 11, SOLVENT BLUE 25, SOLVENT BLUE 35, SOLVENT BLUE 36, SOLVENT BLUE 45, SOLVENT BLUE 55, SOLVENT BLUE 55, SOLVENT BLUE 63, SOLVENT BLUE 63, SOLVENT BLUE 63 , SOLVENT BLUE 104, and the like, and SOLVENT BLUE 87 is preferable in terms of the color tone and transparency of the resulting polyester.

  Anthraquinone-based purple dyes include SOLVENT VIOLET 8, SOLVENT VIOLET 13, SOLVENT VIOLET 14, SOLVENT VIOLET 21, SOLVENT VIOLET 27, SOLVENT VIOLET 28, SOLVENT VIOLET 28, SOLVENT VIOLET 28, SOLVENT VIOLET In view of transparency, SOLVENT VIOLET 13 or SOLVENT VIOLET 36 is preferable.

  In addition, as described above, the polyester resin composition of the present invention is excellent in transparency, but as an index indicating excellent transparency, the haze value is preferably 5.0 or less. It is preferably 8 or less, and more preferably 3.0 or less.

  And the polyester resin composition of this invention needs that intrinsic viscosity (IV) is 0.8-1.5, and it is preferable that it is 1.0-1.3 especially. The intrinsic viscosity (IV) is measured at a temperature of 20 ° C. using a mixture of equal mass of phenol and ethane tetrachloride as a solvent.

  When the intrinsic viscosity is less than 0.8, since the viscosity of the resin composition is low, the drawdown of the parison becomes large during direct blow molding, and molding becomes difficult. On the other hand, when the intrinsic viscosity exceeds 1.5, it is necessary to raise the molding temperature, and the color tone and transparency of the obtained molded product are deteriorated. Moreover, it is not preferable because the swell ratio tends to increase.

  The polyester resin composition of the present invention needs to have a swell ratio (SW) of 1.2 to 1.4, and preferably 1.22 to 1.35. The swell ratio (SW) in the present invention means the size of the die swell (indicating the flow state of the molten resin at the extrusion die outlet), and the larger the value, the larger the expansion at the extrusion die outlet. means. If this value is small, it means that the expansion at the exit of the extrusion die is small.

  As mentioned above, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane is used in order to make the swell ratio within the scope of the present invention. It is important to contain 1.0% by mass. That is, it cannot be achieved only that the intrinsic viscosity is within the above range, but entanglement of molecular chains occurs in the resin composition, and a state similar to crosslinking occurs, so that the swell ratio within the above range can be obtained. .

In addition, the measurement of the swell ratio (SW) in the present invention is performed by taking a photograph of the discharge portion of the molten resin when the polyester resin composition is extruded at an extrusion temperature of 260 ° C. using a direct blow molding machine. The maximum diameter of the molten resin strand extruded from the die is measured and calculated by the following formula.
Swell ratio (SW) = maximum diameter of molten resin strand / die inner diameter

  When the swell ratio is less than 1.2, the expansion at the exit of the extrusion die is reduced in direct blow molding, so that the moldability is deteriorated, and the resulting molded product has thickness unevenness, resulting in reduced quality. Become. On the other hand, if the swell ratio exceeds 1.4, the expansion at the exit of the extrusion die increases, so that the resin composition and the metal (mold) are rubbed at the exit of the extruder, and the resulting molded product has a surface. It becomes rough and inferior in gloss and transparency.

  Moreover, the polyester resin composition of this invention may contain the phosphorus compound for the purpose of the further color tone improvement and the thermal stabilization of polyester. From the viewpoint of cost and the color tone of the resulting polyester resin composition, phosphoric acid or phosphoric acid ester is preferable as the phosphorus compound.

  Next, the manufacturing method of the polyester resin composition of this invention is demonstrated. The polyester resin composition in the present invention is preferably obtained through an esterification reaction, a melt polymerization reaction, and a solid phase polymerization reaction step. It is difficult to obtain a polyester resin composition having a target intrinsic viscosity only by the esterification reaction and the melt polymerization reaction. Even if it is obtained, the reaction time of the melt polymerization reaction becomes long, and the resulting polyester resin composition has a poor color tone.

Specifically, for example, it can be produced by the following method.
Terephthalic acid or its ester-forming derivative as an acid component, ethylene glycol as a glycol component in a predetermined ratio are charged into an esterification reactor, and subjected to an esterification reaction at a temperature of 160 to 280 ° C. under pressure. To a polymerization reactor, 1,4-cyclohexanedimethanol, germanium compound as a polymerization catalyst, anthraquinone blue dye and / or anthraquinone purple dye, tetrakis [methylene-3- (3,5-di-t-butyl -4-Hydroxyphenyl) propionate] methane is added, and a melt polymerization reaction is usually carried out at a temperature of 240 to 290 ° C., preferably 250 to 280 ° C. under a reduced pressure of 1 hPa or less. The intrinsic viscosity of the copolymerized polyester (prepolymer) obtained here is preferably in the range of 0.5 to 0.8.

  Subsequently, a polyester resin composition having a target intrinsic viscosity is obtained by performing a solid phase polymerization reaction using the prepolymer obtained by the melt polymerization reaction. In the solid phase polymerization, after prepolymer is dried and crystallized in advance, usually under reduced pressure or under an inert gas such as nitrogen, the temperature is 20 to 30 ° C. lower than the melting point of the polyester resin for 3 hours to The reaction is carried out in the reactor for 70 hours.

  As described above, the polyester resin composition of the present invention is particularly suitable for direct blow molding, but even if an injection molding or stretching method is adopted, it is a molded product excellent in color tone and transparency (injection). Molded bodies, sheets, films, etc.) can be obtained.

  Next, the direct blow molded article of the present invention is composed of the polyester resin composition of the present invention. The direct blow molded article of the present invention can be manufactured using a general-purpose direct blow molding machine, and the temperature of each part of the cylinder and the nozzle of the molding machine is preferably in the range of 240 to 290 ° C.

Next, the present invention will be specifically described using examples. The measurement and evaluation methods for various characteristic values in the examples are as follows.
(A) Intrinsic viscosity It was measured by the same method as described above.
(B) Copolymerization component copolymerization content, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane content The resulting resin composition was deuterated. Hexafluoroisopropanol and deuterated chloroform were dissolved in a mixed solvent having a volume ratio of 1/20, and 1H-NMR was measured with a LA-400 NMR apparatus manufactured by JEOL Ltd. From the integrated intensity of the proton peak, the copolymerization amount and content were determined.
(C) Content of Germanium Compound and Antimony Compound The obtained resin composition was measured using a fluorescent X-ray analyzer 3270 manufactured by Rigaku Corporation.
(D) Swell ratio It measured by the method similar to the above.
(E) Formability The thickness of the body part of the obtained molded product (20 samples) is measured, and the thickness difference between the thickest part and the thinnest part is up to 0.10 mm. In the case where the number of samples is 18 or more, it was evaluated as “◯”, and in the case where the number of accepted samples was 17 or less, it was evaluated as “x”. Even if the difference between the thickness of the thickest part and the thinnest part is 0.10 mm, crystallization occurs in the molded container, and the container is whitened or the container surface is rough. , Rejected.
(F) Color tone Sample pieces (20 pieces) were cut out from the obtained molded product, and the color tone of the sample pieces was measured using a color difference meter ND-Σ80 type manufactured by Nippon Denshoku Industries Co., Ltd. The color tone was determined with a Hunter Lab colorimeter, the b value was measured, and the average value of n number 20 was obtained. A b value of 1.0 or less was determined to be good color tone.
(G) Haze Cut out from the obtained molded product to prepare sample pieces (20 pieces), turbidity was measured with a turbidimeter MODEL 1001DP manufactured by Nippon Denshoku Industries Co., Ltd. (air: haze 0%), n number An average value of 20 was used. The smaller this value is, the better the transparency is, and if it is 5% or less, it is judged that the transparency is excellent.

Example 1
60.3 parts by mass of a reaction product of TPA and EG was charged into a polymerization reactor, followed by 3.9 parts by mass of 1,4-cyclohexanedimethanol, 0.008 parts by mass of germanium dioxide as a polymerization catalyst, and anthraquinone purple dye SOLVENT VIOLET 13 (FS Violet 1805 manufactured by Arimoto Chemical Industry Co., Ltd.) 1.8 × 10 ⁻⁴ parts by mass, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] 0.12 parts by mass of methane (Irganox-1010 manufactured by Ciba Specialties Co., Ltd.) was added respectively, and the reactor was decompressed, and after 60 minutes, a final polymerization pressure of 0.9 hPa and a temperature of 280 ° C. were performed for 4 hours, and a melt polymerization reaction was performed. A prepolymer of copolyester was obtained.
This prepolymer had an intrinsic viscosity of 0.72. This prepolymer was pre-dried at 150 ° C. for 5 hours, and then solid-phase polymerized in a nitrogen stream at 210 ° C. for 15 hours to obtain a polyester resin composition.
After drying using this polyester resin composition, it was molded using a direct blow molding machine when the extrusion temperature was 260 ° C., the parison diameter was 3 cm, and the length was 25 cm to obtain a 500 cc hollow container.

Examples 2-12, Comparative Examples 1-5, Comparative Examples 8-9
Copolymerization amount of 1,4-cyclohexanedimethanol, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane content, germanium compound, anthraquinone dye type and The composition was changed so that the content was the value shown in Table 1, and a polyester resin composition was obtained in the same manner as in Example 1.
In addition, SOLVENT VIOLET 36 in Table 1 is an anthraquinone purple dye, and is FS Violet 1803 manufactured by Arimoto Chemical Industry. SOLVENT BLUE 104 in Table 1 is an anthraquinone blue dye, and is FS Blue 1547 manufactured by Arimoto Chemical Industry.
And the direct blow molding goods were obtained like Example 1 using the obtained resin composition.

Comparative Example 6
A polyester resin composition was obtained in the same manner as in Example 1 except that the solid phase polymerization reaction time was changed and the intrinsic viscosity was the value shown in Table 1.
And the direct blow molding goods were obtained like Example 1 using the obtained resin composition.

Comparative Example 7
A polyester resin composition was obtained in the same manner as in Example 1 except that an antimony compound was used as a polymerization catalyst and 0.018 parts by mass of antimony trioxide was added.
And the direct blow molding goods were obtained like Example 1 using the obtained resin composition.

  Table 1 shows the composition of the polyester resin compositions obtained in Examples 1 to 12 and Comparative Examples 1 to 9, the intrinsic viscosity, the swell ratio value, the moldability evaluation, the color tone of the molded product, and the haze value.

  As is clear from Table 1, the polyester resin compositions obtained in Examples 1 to 12 had values of intrinsic viscosity and swell ratio within the ranges specified in the present invention, and were excellent in thermal stability. The direct blow molding could be performed with good operability without causing the problem of whitening due to crystallization. The obtained direct blow molded article (container) had a high evaluation of moldability, was not colored, had excellent color tone, and had good transparency.

On the other hand, since the polyester resin composition obtained in Comparative Example 1 had a small amount of 1,4-cyclohexanedimethanol, the molded product was crystallized and whitened when direct blow molding was performed, and the transparency was poor. It became. In Comparative Example 2, since the copolymerization amount of 1,4-cyclohexanedimethanol was large, fusion occurred during solid phase polymerization, and polyester could not be obtained. Since the polyester resin composition obtained in Comparative Example 3 had a low content of tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, Stability deteriorated and the molded product was inferior in color tone. Moreover, since the swell ratio was low and the drawdown of the parison during molding was large, the molded product had a large difference between the thickest part and the thinnest part, resulting in poor moldability. Since the polyester resin composition obtained in Comparative Example 4 contained a large amount of tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, the swell ratio increased. The expansion of the resin composition at the exit of the extrusion die during molding was too large, and the resulting molded product was rough and the transparency was impaired. The polyester resin composition obtained in Comparative Example 5 had a low intrinsic viscosity because the content of the germanium compound was small, and direct blow molding was not possible. Since the polyester resin composition obtained in Comparative Example 6 had a longer solid phase polymerization reaction time, both the intrinsic viscosity and the swell ratio were too high. For this reason, it is necessary to increase the molding temperature at the time of direct blow molding, and the expansion of the resin composition becomes too large at the time of molding, and the obtained molded product has a poor color tone, the surface is rough, and the transparency is inferior. became. Since the polyester resin composition obtained in Comparative Example 7 used an antimony compound as a polymerization catalyst, the molded article was inferior in transparency. The polyester resin composition obtained in Comparative Example 8 had a poor color tone due to the small amount of anthraquinone dye added. The polyester resin composition obtained in Comparative Example 9 had poor transparency because of the large amount of anthraquinone dye added.

Claims (2)

In a polyester resin in which 80 mol% or more of the acid component constituting the polyester is terephthalic acid, 2 to 20 mol% of the glycol component is 1,4-cyclohexanedimethanol, and 80 to 98 mol% is ethylene glycol, tetrakis [Methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] containing 0.1 to 1.0% by mass of methane, and the germanium compound with respect to 1 mol of the acid component of the polyester resin A resin composition containing 5 × 10 ⁻⁵ mol to 3.0 × 10 ⁻⁴ mol, and further containing 0.5 to 5 ppm of at least one of an anthraquinone blue dye and an anthraquinone purple dye, and having an intrinsic viscosity (IV ) Is 0.8 to 1.5, and the swell ratio (SW) is 1.2 to 1.4. A direct blow molded article comprising the polyester resin composition according to claim 1.