JP2010235938A - Aromatic polyester and polyester molded article comprising the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aromatic polyester and a polyester molded article comprising it excellent in transparency, heat-resistance, mechanical characteristic and aroma retention property and capable of being advantageously used as a vessel for a food or a beverage and a packaging material. <P>SOLUTION: The aromatic polyester includes a repetition unit comprising an aromatic dicarboxylic acid component and a glycol component. In the aromatic polyester, when a bitter taste value and an astringency value of extraction water obtained by performing extraction treatment of the molded article comprising the aromatic polyester in ultra-pure water at 80°C for one hour are measured by a taste inspection apparatus provided with a taste sensor comprising an artificial lipid membrane, the difference of the bitter taste value of the extraction water and the bitter taste value of the ultra-pure water and the difference of the astringency value of the extraction water and the astringency value of the ultra-pure water are each 0.5 or less. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an aromatic polyester that is excellent in transparency, heat resistance, mechanical properties, and aroma retention, and can be advantageously used as a container or packaging material for food or beverages.

Thermoplastic polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as “PET”) are excellent in both mechanical and chemical properties, and thus have high industrial value and are widely used as fibers, films, sheets, bottles and the like. in use. Furthermore, since thermoplastic polyester is excellent in heat resistance, transparency and gas barrier properties, it is particularly suitable as a material for packaging materials such as containers for filling beverages such as juices, soft drinks and carbonated drinks.
For example, such a thermoplastic polyester is supplied to a molding machine such as an injection molding machine to form a preform for a hollow molded body, and the preform is inserted into a mold having a predetermined shape and stretch blow molded. In general, the body is heat-treated (heat set) to be formed into a hollow molded container, and further, the stopper of the bottle is heat treated (crystallization of the stopper) as required.
However, PET contains acetaldehyde (hereinafter sometimes abbreviated as AA) as a by-product during melt polycondensation. Moreover, PET produced acetaldehyde by thermal decomposition when thermoforming a molded body such as a hollow molded body, and the acetaldehyde content in the material of the obtained molded body increased, and the hollow molded body was filled. Affects the flavor and odor of beverages. Therefore, various measures have been conventionally taken to reduce the acetaldehyde content in the polyester molded body. In general, a method of reducing the AA content by solid-phase polymerization of melt-polycondensed polyester (see, for example, Patent Documents 1 and 2), a copolymer polyester having a lower melting point is used at the time of molding. A method for reducing AA generation (see, for example, Patent Documents 3 and 4), a method for reducing the molding temperature as much as possible during thermoforming, and a method for reducing the shear stress as much as possible during thermoforming (for example, And the like are known.

In addition, in order to suppress the generation of by-products such as acetaldehyde and formaldehyde during the solid-phase polymerization reaction, the reaction is carried out in the absence of oxygen and under an inert gas stream containing hydrogen. A method has been proposed in which the oxygen concentration in the active gas is 0.1 mol% or less in the total gas, and the amount of hydrogen in the inert gas is 0.1 mol% or more and 70 mol% or less in the total gas. (For example, refer to Patent Document 6).
Further, in order to reduce acetaldehyde and formaldehyde in the beverage container after molding, there is also a method of drying solid-phase polymerized PET in the absence of oxygen and in an inert gas stream containing hydrogen (for example, Patent Document 7). reference).

In recent years, thermoplastic polyester containers mainly made of polyethylene terephthalate have come to be used as containers for low flavor beverages such as mineral water and oolong tea. In the case of such beverages, these sterilized polyester containers are generally heat-filled with these beverages, or heated after being filled and sterilized. In addition, these beverages may be filled in the polyester container sterilized separately after sterilization at a low temperature.
As a technique for solving the problem of flavor and odor, a method of using a polyester composition in which 0.05 parts by weight or more and less than 1 part by weight of a metaxylylene group-containing polyamide resin is added to 100 parts by weight of a thermoplastic polyester resin. (For example, refer to Patent Document 8) and a polyester container (for example, refer to Patent Document 9) made of a polyester composition containing a specific polyamide with a terminal amino group concentration regulated within a certain range in a thermoplastic polyester is proposed. Has been. In addition, by reducing the free monomer content and free oligomer content in the polyethylene terephthalate resin, the flavor of the container obtained from the resin is judged and improved by a test method judging by a sensory test. PET resin (see, for example, Patent Document 10) has been proposed.
In addition, it has been studied to laminate a thermoplastic polyester film having good heat resistance on a metal plate and to use the laminated metal plate mainly for metal cans for food containers such as soft drinks, beer and canned foods. In such applications, in order to improve flavor retention, a thermoplastic polyester film for laminating metal plates with an acetaldehyde content of 20 ppm or less (see, for example, Patent Document 11) has been proposed.
As described above, the flavor property has been improved to a practically sufficient level, that is, to a level that can be satisfied in the current distribution, by greatly reducing the acetaldehyde content. On the other hand, we have pursued polyester resins suitable for even more delicious beverage containers, but in order to improve the subtle taste, there is something as a countermeasure just by reducing the acetaldehyde content in the polyester resin. He found himself lacking, and therefore set himself the task of developing a polyester resin that could withstand taste-advanced beverages.

JP-A-53-73288 JP 54-149793 A Japanese Patent Publication No.53-28676 Japanese Patent Laid-Open No. 57-16024 JP-A-57-39937 Japanese Patent Laid-Open No. 9-3179 Japanese Patent Laid-Open No. 9-3182 Japanese Examined Patent Publication No. 6-6661 Japanese Examined Patent Publication No. 4-71425 JP-A-11-106491 Japanese Patent Laid-Open No. 5-339393

  An object of the present invention is to solve the above-mentioned problems of the prior art, and is excellent in transparency, heat resistance, mechanical properties and aroma retention, and is advantageously used as a container for food or beverages, and a packaging material. An aromatic polyester that can be used, and a polyester molded article comprising the same.

The inventors of the present invention have made various studies on aromatic polyesters that have a repeating unit mainly composed of an aromatic dicarboxylic acid component and a glycol component and give a polyester molded article excellent in transparency, hue, and flavor retention. Was completed.
That is, the aromatic polyester of the present invention is an aromatic polyester having a repeating unit consisting of an aromatic dicarboxylic acid component and a glycol component, and the molded article made of the aromatic polyester is heated at 80 ° C. in ultrapure water at 1 ° C. When the bitterness value and astringency value of the extracted water obtained by carrying out the time extraction process are measured with a taste inspection device equipped with a taste sensor made of an artificial lipid membrane, the bitterness value of the extracted water and the bitterness of ultrapure water The aromatic polyester is characterized in that the difference in value and the difference between the astringency value of the extracted water and the astringency value of the ultrapure water are each 0.5 or less.

In addition, as a taste inspection apparatus (hereinafter, simply referred to as a taste inspection apparatus) having a taste sensor made of an artificial lipid membrane that can be used, for example, “Taste Recognition Apparatus” manufactured by Intelligent Sensor Technology Co., Ltd. SA402B ". Further, the taste inspection apparatus and the measuring method are described in the following patent publications.
JP-A-2002-107339, JP-A-2002-107338, JP-A-2001-264289, JP-A-2000-171423, WO096 / 30753, and the like. Artificial lipid membranes that specifically detect bitterness The taste inspection apparatus is disclosed in, for example, the aforementioned Japanese Patent Application Laid-Open No. 2002-107339, and can simultaneously measure tastes such as sourness in addition to bitterness and astringency.
The bitterness and astringency test method in the present invention will be described in the following measurement section.

In this case, the acetaldehyde content can be 10 ppm or less.
In this case, the content of the cyclic ester oligomer can be 0.70% by weight or less.
In this case, the increase amount of the cyclic ester oligomer when melted at a temperature of 290 ° C. for 60 minutes can be 0.40% by weight or less.
In this case, the aromatic polyester formed into a chip shape after polycondensation can be treated with water at 20 to 120 ° C.
In this case, it can be a polyester molded body obtained by melt-molding the aromatic polyester.
In this case, the polyester molded article of the present invention can be any one of a hollow molded article, a sheet-like article, a stretched film formed by stretching the sheet-like article in at least one direction, or a nonwoven fabric.
Moreover, in this case, it can be a coating characterized by melting and extruding the above-mentioned aromatic polyester on a substrate.

  The aromatic polyester of the present invention can provide a polyester molded article having excellent fragrance retention properties and excellent transparency, heat resistance and mechanical properties. In particular, it is an aromatic polyester useful as a packaging material for low flavor beverages. In addition, the aromatic polyester of the present invention does not contaminate the mold or metal roll during molding, has excellent long-term continuous moldability, and can meet high quality requirements in the molding field such as containers and sheets. Moreover, the polyester molded body of the present invention is excellent in pressure resistance and heat-resistant dimensional stability.

It is a top view of a step forming board. It is a side view of a stepped molding plate. It is the schematic of the water treatment apparatus used in the Example. It is a fluorescence spectrum of PET.

Hereinafter, embodiments of the aromatic polyester of the present invention will be specifically described.
The aromatic polyester of the present invention is a thermoplastic polyester having a repeating unit composed of an aromatic dicarboxylic acid component and a glycol component, and the aromatic dicarboxylic acid unit preferably contains 80 mol% or more of the acid component, more preferably. It is particularly preferable that the aromatic dicarboxylic acid unit is 85 mol% or more of the acid component and the aromatic dicarboxylic acid unit is 95 mol% or more of the acid component.
Examples of the aromatic dicarboxylic acid component constituting the aromatic polyester of the present invention include terephthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl-4,4′-dicarboxylic acid, diphenoxyethanedicarboxylic acid and the like, and Examples thereof include functional derivatives thereof.

  Examples of the glycol component constituting the aromatic polyester of the present invention include aliphatic glycols such as ethylene glycol, 1,3-trimethylene glycol and tetramethylene glycol, and alicyclic glycols such as cyclohexanedimethanol.

  As the dicarboxylic acid as a copolymerization component used when the aromatic polyester of the present invention is a copolymer, the above-mentioned acids, isophthalic acid, diphenyl-4,4′-dicarboxylic acid, diphenoxyethanedicarboxylic acid, Aromatic dicarboxylic acids such as 4,4′-diphenyl ether dicarboxylic acid, 4,4′-diphenyl ketone dicarboxylic acid and functional derivatives thereof, oxyacids such as p-oxybenzoic acid and oxycaproic acid and functional derivatives thereof, adipine Aliphatic dicarboxylic acids such as acid, sebacic acid, succinic acid, glutaric acid and dimer acid and functional derivatives thereof, alicyclic dicarboxylic acids such as hexahydroterephthalic acid, hexahydroisophthalic acid and cyclohexanedicarboxylic acid and functional derivatives thereof Etc.

Examples of the glycol as a copolymer component used when the aromatic polyester of the present invention is a copolymer include ethylene glycol, diethylene glycol, 1,3-trimethylene glycol, tetramethylene glycol, pentamethylene glycol, and hexamethylene glycol. , Octamethylene glycol, decamethylene glycol, 2-ethyl-2-butyl-1,3-propanediol, neopentyl glycol, dimer glycol and other aliphatic glycols, 1,2-cyclohexanediol, 1,4-cyclohexanediol, Alicyclic glycols such as 1,1-cyclohexanedimethylol, 1,4-cyclohexanedimethylol, 2,5-norbornane dimethylol, xylylene glycol, 4,4′-dihydroxybiphenyl, 2,2-biphenyl Aromatic glycols such as poly (4′-β-hydroxyethoxyphenyl) propane, bis (4-hydroxyphenyl) sulfone, bis (4-β-hydroxyethoxyphenyl) sulfonic acid, alkylene oxide adducts of bisphenol A, polyethylene glycol And polyalkylene glycols such as polybutylene glycol.
Furthermore, as a polyfunctional compound as a copolymerization component used when the aromatic polyester of the present invention is a copolymer, trimellitic acid, pyromellitic acid and the like can be exemplified as an acid component, a glycol component Examples thereof include glycerin and pentaerythritol. The amount of the above copolymerization component used should be such that the aromatic polyester remains substantially linear. Monofunctional compounds such as benzoic acid and naphthoic acid may be copolymerized.

A preferred example of the aromatic polyester of the present invention is an aromatic polyester whose main structural unit is composed of ethylene terephthalate, more preferably 70 mol% or more of ethylene terephthalate units, and isophthalic acid, 1,4 as a copolymerization component. -Copolyester containing cyclohexanedimethanol and the like, particularly preferably aromatic polyester containing 95 mol% or more of ethylene terephthalate units.
Examples of these aromatic polyesters include polyethylene terephthalate (hereinafter abbreviated as PET), poly (ethylene terephthalate-ethylene isophthalate) copolymer, poly (ethylene terephthalate-1,4-cyclohexanedimethylene terephthalate) copolymer, Examples include poly (ethylene terephthalate-dioxyethylene terephthalate) copolymer, poly (ethylene terephthalate-1,3-propylene terephthalate) copolymer, poly (ethylene terephthalate-ethylenecyclohexylene dicarboxylate) copolymer, and the like.

In addition, other preferable examples of the aromatic polyester of the present invention are aromatic polyesters whose main structural unit is composed of 1,3-propylene terephthalate, and more preferably 70 mol% of 1,3-propylene terephthalate units. Aromatic polyesters containing at least 95 mol% of 1,3-propylene terephthalate units are particularly preferred.
Examples of these polyesters include polypropylene terephthalate (PTT), poly (1,3-propylene terephthalate-1,3-propylene isophthalate) copolymer, poly (1,3-propylene terephthalate-1,4-cyclohexanedimethylene). Terephthalate) copolymer and the like.

Further, as another preferred example of the aromatic polyester of the present invention, the main structural unit is an aromatic polyester composed of butylene terephthalate, more preferably a copolymer polyester containing 70 mol% or more of butylene terephthalate units, Particularly preferred is an aromatic polyester containing 95 mol% or more of butylene terephthalate units.
Examples of these aromatic polyesters include polybutylene terephthalate (PBT), poly (butylene terephthalate-butylene isophthalate) copolymer, poly (brene terephthalate-1,4-cyclohexanedimethylene terephthalate) copolymer, poly (butylene). And a terephthalate-1,3-propylene terephthalate) copolymer and a poly (butylene terephthalate-butylenecyclohexylene dicarboxylate) copolymer.

Further, another preferred example of the aromatic polyester of the present invention is a thermoplastic polyester whose main structural unit is composed of ethylene-2,6-naphthalate, and more preferably 70 mol of ethylene-2,6-naphthalate unit. %, And particularly preferred is a thermoplastic polyester containing 90 mol% or more of ethylene-2,6-naphthalate units.
Examples of these thermoplastic polyesters include polyethylene-2,6-naphthalate (PEN), poly (ethylene-2,6-naphthalate-ethylene terephthalate) copolymer, poly (ethylene-2,6-naphthalate-ethylene isophthalate). ) Copolymer, poly (ethylene-2,6-naphthalate-dioxyethylene-2,6-naphthalate) copolymer, and the like.

Further, another preferred example of the aromatic polyester of the present invention is an aromatic polyester in which the main structural unit is composed of 1,4-cyclohexanedimethylene terephthalate, and more preferably 1,4-cyclohexanedimethylene terephthalate unit. It is a copolyester containing 70 mol% or more, particularly preferably an aromatic polyester containing 90 mol% or more of 1,4-cyclohexanedimethylene terephthalate units.
Examples of these thermoplastic polyesters include poly-1,4-cyclohexanedimethylene terephthalate (PCT), poly (1,4-cyclohexanedimethylene terephthalate-ethylene terephthalate) copolymer, and the like.

  The aromatic polyester of the present invention can basically be produced by applying a conventionally known melt polycondensation method-solid phase polymerization method. The melt polycondensation reaction may be performed in one stage or may be performed in multiple stages. These may be comprised from a batch-type reaction apparatus, and may be comprised from the continuous-type reaction apparatus. The melt polycondensation step and the solid phase polymerization step may be operated continuously or may be operated separately.

  Hereinafter, an example of a preferable continuous production method of the aromatic polyester of the present invention will be described using polyethylene terephthalate (PET) as an example, but the present invention is not limited thereto. That is, a direct esterification method in which terephthalic acid, ethylene glycol, and if necessary, other copolymerization components are directly reacted and esterified while distilling off water, followed by polycondensation under reduced pressure in the presence of a polycondensation catalyst, Or transesterification by reacting dimethyl terephthalate with ethylene glycol and other copolymerization components if necessary, and transesterifying while distilling off methyl alcohol, followed by polycondensation under reduced pressure in the presence of a polycondensation catalyst As a result, a melt polycondensed polyester is produced.

The aldehyde content of the melt polycondensed polyester is about 100 ppm or less, preferably 80 ppm or less, more preferably 60 ppm or less. If the aldehyde content exceeds 100 ppm, the bitterness and astringency test evaluation results become worse, which is a problem.
In the case of PET or PEN, the aldehydes are acetaldehyde and formaldehyde, and in the case of an aromatic polyester mainly composed of 1,3-propylene terephthalate, it is allyl aldehyde.

  The acid value of the melt polycondensed polyester is 5 to 45 equivalent / t, preferably 10 to 40 equivalent / t, and most preferably 15 to 35 equivalent / t. When the acid value is less than 5 equivalents / t, water-soluble low molecular weight oligomers and aldehydes that are estimated to affect the bitterness and astringency test evaluation results as described above, that is, specifically, free AA content Tends to increase, which is not preferable.

The fluorescence emission intensity (B) at 450 nm in the fluorescence spectrum obtained when the melt polycondensed polyester is irradiated with excitation light having a wavelength of 343 nm is 15 or less, preferably 10 or less, more preferably 5 or less, and most preferably 4 or less. It is.
When the fluorescence emission intensity (B) exceeds 15, the bitterness and astringency test evaluation results are worsened, and at the same time, the hue of the polyester molded article is also worsened.

Further, when the melt polycondensed polyester is heat-treated at a temperature of 180 ° C. for 10 hours, the amount of increase in fluorescence emission intensity is 20 or less, preferably 15 or less, more preferably 10 or less, and most preferably 8 or less. In the case of a polyester resin in which the amount of increase in fluorescence emission intensity exceeds 20, there is a problem that the bitterness and astringency test evaluation results deteriorate.
The measurement of the fluorescence emission intensity and the amount of increase in the fluorescence emission intensity will be described in the measurement method section.

The melt polycondensed polyester having the above-mentioned properties is produced as follows, but is not limited thereto.
First, when a low polymer is produced by an esterification reaction, 1.02 to 2.0 mol, preferably 1.03 to 1.4 mol of ethylene glycol is added to 1 mol of terephthalic acid or an ester derivative thereof. The contained slurry is prepared and continuously fed to the esterification reaction step.

An inert gas having an oxygen concentration of 5 ppm or less, preferably 3 ppm or less, more preferably 2 ppm or less, and most preferably 1 ppm or less is circulated in the gas phase portion of the slurry preparation tank or slurry storage tank together with the raw materials. It is necessary to remove oxygen mixed in and to prevent air from mixing in at the same time. The oxygen concentration in the gas phase needs to be maintained at 100 ppm or less, preferably 70 ppm or less, more preferably 50 ppm or less, even more preferably 30 ppm or less, and most preferably 10 ppm or less.
In particular, high-purity terephthalic acid is usually in the form of powder, and air is contained between the particles, and oxygen is brought into the slurry preparation tank and slurry storage tank. It is desirable that the atmosphere in the atmosphere be an inert gas atmosphere having an oxygen concentration of 200 ppm or less, preferably 100 ppm or less, more preferably 50 ppm or less, still more preferably 30 ppm or less, and most preferably 10 ppm or less.

  Further, since oxygen is also dissolved in ethylene glycol, ethylene glycol is previously bubbled with an inert gas having an oxygen concentration of 5 ppm or less, preferably 3 ppm or less, more preferably 2 ppm or less, most preferably 1 ppm or less, In addition, the slurry preparation tank and the slurry storage tank need to be bubbled with the inert gas as described above after the slurry preparation.

  The esterification reaction is carried out in the gas phase part under conditions where ethylene glycol is refluxed using a single-stage apparatus consisting of one esterification reactor or a multistage apparatus in which at least two esterification reactors are connected in series. Is conducted while circulating an inert gas having an oxygen concentration of 5 ppm or less, preferably 3 ppm or less, more preferably 2 ppm or less, and most preferably 1 ppm or less, and removing water or alcohol generated by the reaction from the system with a rectification column. To do. The oxygen concentration in the gas phase needs to be maintained at 100 ppm or less, preferably 70 ppm or less, more preferably 50 ppm or less, even more preferably 30 ppm or less, and most preferably 10 ppm or less.

The reaction is carried out using a multistage apparatus under conditions where ethylene glycol is refluxed while removing water or alcohol produced by the reaction from the system with a rectification column. The temperature of the first stage esterification reaction is 240 to 270 ° C., preferably 245 to 265 ° C., and the pressure is 0.2 to 3 kg / cm ² G, preferably 0.5 to ² kg / cm ² G. The temperature of the esterification reaction in the final stage is usually 250 to 280 ° C, preferably 255 to 275 ° C, and the pressure is usually 0 to 1.5 kg / cm ² G, preferably 0 to 1.3 kg / cm ² G. . When carried out in three or more stages, the reaction conditions for the esterification reaction in the intermediate stage are conditions between the reaction conditions for the first stage and the reaction conditions for the final stage. The increase in the reaction rate of these esterification reactions is preferably distributed smoothly at each stage. Ultimately, it is desirable that the esterification reaction rate reaches 90% or more, preferably 93% or more. By these esterification reactions, low-order condensates having a molecular weight of about 500 to 5,000 are obtained.
When terephthalic acid is used as a raw material, the esterification reaction can be carried out without a catalyst by the catalytic action of terephthalic acid as an acid, but may be carried out in the presence of a polycondensation catalyst.

  Also, tertiary amines such as triethylamine, tri-n-butylamine, benzyldimethylamine, quaternary ammonium hydroxides such as tetraethylammonium hydroxide, tetra-n-butylammonium hydroxide, trimethylbenzylammonium hydroxide, and lithium carbonate When a small amount of a basic compound such as sodium carbonate, potassium carbonate or sodium acetate is added, the proportion of dioxyethylene terephthalate component units in the main chain of polyethylene terephthalate is relatively low (5% relative to all diol components). Mol% or less).

  The acid value of the melt polycondensed polyester needs to be controlled within the above range, but this is controlled by appropriately adjusting the molar ratio of terephthalic acid and ethylene glycol and the temperature and time of the esterification reaction. I can do it.

Next, in the case of producing a low polymer by transesterification, 1.1 to 2.0 mol, preferably 1.2 to 1.5 mol of ethylene glycol was contained with respect to 1 mol of dimethyl terephthalate. A solution is prepared and continuously fed to the transesterification step.
It is necessary to circulate an inert gas having the same oxygen concentration as in the esterification reaction in the gas phase part of the dimethyl terephthalate solid storage tank or the dimethyl terephthalate melt storage tank. The same precautions as described above are necessary for.

  The transesterification reaction is carried out under conditions where ethylene glycol is returned using a single-stage apparatus consisting of one transesterification reactor or a multistage reaction apparatus in which at least two transesterification reactors are connected in series. An inert gas having an oxygen concentration of 5 ppm or less, preferably 3 ppm or less, more preferably 2 ppm or less, and most preferably 1 ppm or less is circulated in the phase portion, and methanol generated by the reaction is removed from the system by a rectification column. carry out. The oxygen concentration in the gas phase needs to be maintained at 100 ppm or less, preferably 70 ppm or less, more preferably 50 ppm or less, even more preferably 30 ppm or less, and most preferably 10 ppm or less.

  In the case of using a multistage apparatus, the transesterification reaction is carried out by using a rectification column to convert methanol produced by the reaction in a rectifying column under the condition that ethylene glycol is distilled back using an apparatus in which one or two transesterification reactors are connected in series. Perform while removing out of the system. The temperature of the first stage transesterification is 180 to 250 ° C, preferably 200 to 240 ° C. The temperature of the transesterification reaction in the final stage is usually 230 to 270 ° C., preferably 240 to 265 ° C., and as the transesterification catalyst, fatty acid salts such as Zn, Cd, Mg, Mn, Co, Ca, Ba, carbonates Alternatively, Pb, Zn, Sb, Ge oxide or the like is used. A low-order condensate having a molecular weight of about 200 to 500 is obtained by these transesterification reactions.

  Dimethyl terephthalate, terephthalic acid or ethylene glycol, which is the starting material, includes virgin dimethyl terephthalate derived from para-xylene, ethylene glycol derived from terephthalic acid or ethylene, as well as methanol decomposition from used PET bottles. A recovered raw material such as dimethyl terephthalate, terephthalic acid, bishydroxyethyl terephthalate or ethylene glycol recovered by a chemical recycling method such as decomposition of ethylene glycol or ethylene glycol can also be used as at least part of the starting material. Needless to say, the quality of the recovered raw material must be refined to a purity and quality suitable for the intended use.

  Subsequently, the obtained low-order condensate is supplied to a multistage liquid phase condensation polymerization process. The polycondensation reaction conditions are as follows: the first stage polycondensation reaction temperature is 250 to 290 ° C., preferably 260 to 280 ° C., and the pressure is 500 to 20 Torr, preferably 200 to 30 Torr. The temperature is 265 to 300 ° C., preferably 275 to 295 ° C., and the pressure is 10 to 0.1 Torr, preferably 5 to 0.5 Torr. When carried out in three or more stages, the reaction conditions for the intermediate stage polycondensation reaction are conditions between the reaction conditions for the first stage and the reaction conditions for the last stage. The degree of increase in intrinsic viscosity achieved in each of these polycondensation reaction steps is preferably distributed smoothly. A single-stage polycondensation apparatus may be used for the polycondensation reaction.

  Under the polycondensation reaction conditions, it is preferable to increase the degree of vacuum so that the polycondensation reaction proceeds as quickly as possible in a short time. The time for the polycondensation reaction is preferably 1 to 7 hours, and the temperature of 270 ° C. or higher is preferably within 5 hours.

  It is natural that the melt polycondensation reactor should be installed so that air does not leak into the system as much as possible from the design stage, and the melt polycondensation reaction occurs during periodic overhauls such as during regular repairs. It is important to take measures to prevent air leakage to the maximum extent under reduced pressure. In particular, the influence of air leakage from the seal part of the movable part such as a pump used for transport between the stirring shaft and the reaction tank is large, and the seal part has a less leaky structure. Is preferably 3 ppm or less, more preferably 2 ppm or less, and most preferably 1 ppm or less.

  Further, in the second and subsequent stages of polycondensation, particularly as the final stage polycondensation reactor, the polyester stays little and the intermediate stage degree of polyester introduced into the reactor is successively polycondensed to form the final polycondensate. It is preferable to have a high plug flow property. For this purpose, it is preferable to set the shape of the optimum stirring blade and to set the rotation speed of the stirring blade appropriately, and a reactor equipped with a biaxial stirring blade is also preferred.

  The polycondensation reaction is performed using a polycondensation catalyst. As the polycondensation catalyst, at least one compound selected from Ge, Sb, Ti, or Al compounds is preferably used. These compounds are added to the reaction system as powders, aqueous solutions, ethylene glycol solutions, ethylene glycol slurries and the like.

  Examples of the Ge compound include amorphous germanium dioxide, crystalline germanium dioxide powder or ethylene glycol slurry, a solution obtained by heating and dissolving crystalline germanium dioxide in water, or a solution obtained by adding ethylene glycol to this and heat treatment. In particular, in order to obtain the aromatic polyester of the present invention, it is preferable to use a solution in which germanium dioxide is dissolved by heating in water, or a solution in which ethylene glycol is added and heated. In addition, compounds such as germanium tetroxide, germanium hydroxide, germanium oxalate, germanium chloride, germanium tetraethoxide, germanium tetra-n-butoxide, and germanium phosphite can also be used. These polycondensation catalysts can be added during the esterification step. When a Ge compound is used, the amount used is preferably in the range of 10 to 150 ppm, more preferably 13 to 100 ppm, further preferably 15 to 70 ppm, and most preferably 15 to 50 ppm as the residual amount of Ge in the polyester.

  Examples of Ti compounds include tetraethyl titanates, tetraisopropyl titanates, tetra-n-propyl titanates, tetraalkyl titanates such as tetra-n-butyl titanates and partial hydrolysates thereof, titanium acetate, titanyl oxalate, titanyl ammonium oxalate, titanyl oxalate Sodium, titanyl oxalate, titanyl calcium oxalate, titanyl succinate, titanyl succinate, titanium trimellitic acid, titanium sulfate, titanium chloride, titanium halide hydrolyzate, titanium oxalate, titanium fluoride, titanium hexafluoride Titanium with potassium acid, ammonium hexafluorotitanate, cobalt hexafluorotitanate, manganese hexafluorotitanate, titanium acetylacetonate, hydroxy polyvalent carboxylic acid or nitrogen-containing polyvalent carboxylic acid Complex, composite oxide composed of titanium and silicon or zirconium, reaction product of titanium alkoxide and phosphorus compound, reaction product of titanium alkoxide and aromatic polycarboxylic acid or its acid anhydride and specific phosphorus compound Thing etc. are mentioned. The Ti compound is added so that the amount of Ti remaining in the produced polymer is 0.1 to 50 ppm, preferably 0.5 to 10 ppm.

  Examples of the Sb compound include antimony trioxide, antimony acetate, antimony tartrate, antimony potassium tartrate, antimony oxychloride, antimony glycolate, antimony pentoxide, and triphenylantimony. The Sb compound is added so that the amount of Sb remaining in the produced polymer is in the range of 50 to 300 ppm, preferably 50 to 250 ppm, more preferably 50 to 200 ppm, and most preferably 50 to 180 ppm.

  Al compounds include aluminum acetate, basic aluminum acetate, aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride, aluminum carbonate, aluminum phosphate, aluminum phosphonate and other inorganic acid salts, aluminum n-propoxide, aluminum iso-propoxide Aluminum alkoxides such as aluminum n-butoxide and aluminum t-butoxide, aluminum chelate compounds such as aluminum acetylacetonate, aluminum acetylacetate, aluminum ethylacetoacetate, aluminum ethylacetoacetate diiso-propoxide, trimethylaluminum, triethylaluminum, etc. Organic aluminum compounds and partial hydrolysates thereof, aluminum oxide, etc. It is. Of these, aluminum acetate, basic aluminum acetate, aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride and aluminum acetylacetonate are particularly preferred. The Al compound is added so that the residual amount of Al in the produced polymer is in the range of 5 to 200 ppm, preferably 10 to 100 ppm, preferably 10 to 50 ppm, and most preferably 12 to 30 ppm.

  In the production of the aromatic polyester of the present invention, an alkali metal compound or an alkaline earth metal compound may be used in combination as necessary. The alkali metal or alkaline earth metal is preferably at least one selected from Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, and Ba, and the use of an alkali metal or a compound thereof is preferable. More preferred. When using an alkali metal or a compound thereof, use of Li, Na, K is particularly preferable.

  Examples of the alkali metal and alkaline earth metal compounds include saturated aliphatic carboxylates such as formic acid, acetic acid, propionic acid, butyric acid, and succinic acid, and unsaturated aliphatic carboxylates such as acrylic acid and methacrylic acid. , Aromatic carboxylates such as benzoic acid, halogen-containing carboxylates such as trichloroacetic acid, hydroxycarboxylates such as lactic acid, citric acid and salicylic acid, carbonic acid, sulfuric acid, nitric acid, phosphoric acid, phosphonic acid, hydrogen carbonate, phosphorus Inorganic acid salts such as acid hydrogen, hydrogen sulfide, sulfurous acid, thiosulfuric acid, hydrochloric acid, hydrobromic acid, chloric acid and bromic acid, and organic sulfonates such as 1-propanesulfonic acid, 1-pentanesulfonic acid and naphthalenesulfonic acid , Organic sulfates such as lauryl sulfate, methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxy, tert-butyl Alkoxides such as alkoxy, chelate compounds and the like acetylacetonate, hydrides, oxides, and hydroxides and the like.

  The alkali metal compound or alkaline earth metal compound is added to the reaction system as a powder, an aqueous solution, an ethylene glycol solution, or the like. The alkali metal compound or alkaline earth metal compound is added so that the residual amount of these elements in the produced polymer is in the range of 1 to 50 ppm.

  Furthermore, the aromatic polyester of the present invention is at least one selected from the group consisting of silicon, manganese, iron, cobalt, zinc, gallium, strontium, zirconium, niobium, molybdenum, indium, tin, hafnium, thallium, tungsten. You may contain the metal compound containing these elements. These metal compounds include saturated aliphatic carboxylates such as acetates of these elements, unsaturated aliphatic carboxylates such as acrylates, aromatic carboxylates such as benzoic acid, and halogens such as trichloroacetic acid. Hydroxycarboxylates such as carboxylates and lactates, inorganic acid salts such as carbonates, organic sulfonates such as 1-propanesulfonate, organic sulfates such as lauryl sulfate, oxides, hydroxides, chlorides Products, alkoxides, acetylacetonates, and the like, and are added to the reaction system as powders, aqueous solutions, ethylene glycol solutions, ethylene glycol slurries, and the like. These metal compounds are added so that the residual amount of elements of these metal compounds per ton of the produced polymer is in the range of 0.05 to 3.0 mol. These metal compounds can be added at any stage of the polyester formation reaction step.

  Also, as stabilizers, phosphoric acid, phosphoric acid esters such as polyphosphoric acid and trimethyl phosphate, phosphonic acid compounds, phosphinic acid compounds, phosphine oxide compounds, phosphonous acid compounds, phosphinic acid compounds, phosphine compounds It is preferable to use at least one phosphorus compound selected from the group consisting of: Specific examples include phosphoric acid, phosphoric acid trimethyl ester, phosphoric acid triethyl ester, phosphoric acid tributyl ester, phosphoric acid triphenyl ester, phosphoric acid monomethyl ester, phosphoric acid dimethyl ester, phosphoric acid monobutyl ester, phosphoric acid dibutyl ester, Phosphoric acid, phosphorous acid trimethyl ester, phosphorous acid triethyl ester, phosphorous acid tributyl ester, methylphosphonic acid, methylphosphonic acid dimethyl ester, ethylphosphonic acid dimethyl ester, phenylphosphonic acid dimethylester, phenylphosphonic acid diethylester, phenylphosphonic acid Diphenyl ester and the like. These stabilizers can be added during the esterification reaction step from a slurry preparation tank of terephthalic acid and ethylene glycol. The P compound is added so that the residual amount of P in the produced polymer is preferably in the range of 5 to 100 ppm, preferably 10 to 90 ppm, preferably 10 to 80 ppm, and most preferably 20 to 70 ppm.

  When an Al compound is used as the polycondensation catalyst, it is preferably used in combination with a phosphorus compound, and is preferably used as a solution or slurry in which an aluminum compound and a phosphorus compound are previously mixed in a solvent. In this case, a more preferable phosphorus compound is at least one phosphorus compound selected from the group consisting of phosphonic acid compounds, phosphinic acid compounds, phosphine oxide compounds, phosphonous acid compounds, phosphinic acid compounds, and phosphine compounds. It is. By using these phosphorus compounds, an effect of improving the catalytic activity is seen, and an effect of improving physical properties such as thermal stability of the aromatic polyester is seen. Among these, use of a phosphonic acid compound is preferable because of its great effect of improving physical properties and improving catalytic activity. Among the above-described phosphorus compounds, the use of a compound having an aromatic ring structure is preferable because the physical property improving effect and the catalytic activity improving effect are great.

  Further, the solution, slurry, etc. of the catalyst and stabilizer described above are bubbled with an inert gas having an oxygen concentration of 5 ppm or less, preferably 3 ppm or less, more preferably 2 ppm or less, most preferably 1 ppm or less at the time of preparation or after preparation. Alternatively, it is necessary that the same inert gas be circulated in the gas phase after bubbling with the inert gas in the same manner.

  The melt polycondensation polyester obtained as described above is, for example, a method in which the melt polyester is extruded into water from the die pores after completion of the melt polycondensation and cut in water, or after the melt polycondensation is finished in the air from the die pores. After being extruded into strands, the chips are formed into columns, spheres, squares or plates by a method of forming chips while cooling with cooling water. Further, the melt polycondensed polyester obtained as described above is converted into chips after the completion of the melt polycondensation, so that it is kept in a molten state at a temperature as low as possible until it is extruded from the pores. It is necessary. The holding condition in the molten state after completion of the melt polycondensation is a melting point or more and 290 ° C. or less, preferably 285 ° C. or less, more preferably 280 ° C. or less within 20 minutes, preferably within 15 minutes, more preferably 10 Within 5 minutes, particularly preferably within 5 minutes, is desirable, and it is necessary to design a pipe or the like so that it is rapidly formed into a cooling chip after melt polycondensation.

  In addition, when extruding the polyester melt from the pores of the die after melt polycondensation into the atmosphere and then cutting into chips by cooling with cooling water, let inert gas come out of the pores of the die. It is also preferred that the molten polymer be sprayed so that oxygen is not adsorbed by the hot resin before it contacts the cooling water. The oxygen concentration of the inert gas to be sprayed is 5 ppm or less, preferably 3 ppm or less, more preferably 2 ppm or less, and most preferably 1 ppm or less.

  Also, in the case of adopting a method of cooling the molten resin by spraying it on the molten resin, oxygen is dissolved in the cooling water and the dissolved oxygen concentration is increased, so the oxygen concentration in the gas phase in the cooling step is 500 ppm or less. Preferably, it is preferably 300 ppm or less, more preferably 100 ppm or less, still more preferably 50 ppm or less, and most preferably 10 ppm or less, and the fluctuation range is kept within 30%, preferably within 20%. As a method for controlling the oxygen concentration in the gas phase in the cooling step, it is preferable to flow the inert gas sprayed onto the molten polymer as it is in the cooling step.

Moreover, it is necessary to use water that satisfies all of the following (1) to (5) as the cooling water when the melt polycondensed polyester is made into chips.
Na ≦ 1.0 (ppm) (1)
Mg ≦ 1.0 (ppm) (2)
Si ≦ 2.0 (ppm) (3)
Ca ≦ 1.0 (ppm) (4)
COD ≤ 2.0 (mg / l) (5)
The sodium content (Na) in the cooling water is preferably Na ≦ 0.5 ppm, more preferably Na ≦ 0.1 ppm. The magnesium content (Mg) in the cooling water is preferably Mg ≦ 0.5 ppm, more preferably Mg ≦ 0.1 ppm. Further, the content (Si) of silicon in the cooling water is preferably Si ≦ 0.5 ppm, more preferably Si ≦ 0.3 ppm. Furthermore, the calcium content (Ca) in the cooling water is preferably Ca ≦ 0.5 ppm, more preferably Ca ≦ 0.1 ppm.

  The cooling water has a COD of 0.1 to 2.0 mg / l, preferably 0.1 to 1.5 mg / l, and more preferably 0.1 to 1.0 mg / l.

  In order to reduce sodium, magnesium, calcium, and silicon in the cooling water, an apparatus for removing sodium, magnesium, calcium, and silicon is installed in at least one place until the industrial water is sent to the chip cooling process. Also, a filter is installed to remove clay minerals such as silicon dioxide and aluminosilicate particles. Examples of the device for removing sodium, magnesium, calcium, and silicon include an ion exchange device, an ultrafiltration device, and a reverse osmosis membrane device.

  Further, in order to reduce the COD of the cooling water, an apparatus for reducing the COD of water is installed in at least one place in the process until the industrial water is sent to the chip forming process for supplying to the chip forming process. Furthermore, an apparatus for reducing COD may be installed in at least one place in the process until the water discharged from the chip forming process is returned to the chip forming process again. Examples of the device for reducing COD include a device for performing microfiltration, coagulation precipitation, and activated carbon treatment.

  The intrinsic viscosity of the melt polycondensed polyester thus obtained is 0.40 to 0.80 deciliter / gram, preferably 0.42 to 0.78 deciliter / gram, and more preferably 0.45 to 0.8. It is preferably in the range of 7 deciliter / gram, most preferably 0.50 to 0.70 deciliter / gram.

  When producing the melt polycondensed polyester as described above, from the storage step of terephthalic acid to the step of chip formation, as described above, the oxygen concentration in the atmosphere or solution of the reactor, catalyst preparation / storage tank, etc. It is important to manage as described above.

  The melt polycondensed polyester is then subjected to a precrystallization, crystallization, and solid phase polymerization process in order to reduce the content of cyclic oligomer content and flavor, such as water-soluble low molecular weight oligomers and aldehydes. Is processed.

It is necessary to adjust the moisture polycondensation polyester chip to a moisture content of 12000 ppm to 3000 ppm, more preferably 10,000 ppm to 4000 pmm, and most preferably 9000 ppm to 5000 ppm in an inert gas atmosphere.
If the moisture content of the melt polycondensed polyester chip exceeds 12000 ppm, hydrolysis occurs during crystallization and the molecular weight tends to decrease, which is not preferable. Moreover, if it is less than 3000 ppm, AA considered to affect the flavor property evaluated by a taste sensory test, a bitter taste, astringency test, etc. tends to increase, and it is not preferable.
Then, in an inert gas atmosphere with an oxygen concentration of preferably 100 ppm or less, more preferably 50 ppm or less, even more preferably 30 ppm or less, and most preferably 20 ppm or less, at least one continuous crystallization apparatus, preferably two or more stages. Pre-crystallization and crystallization are preferably performed in a continuous crystallization apparatus.

To reduce subtle bitterness and astringency that cannot be achieved only by reducing the AA content, heating at various specific wavelengths using near-infrared heaters in the pre-crystallization, crystallization, and solid-phase polymerization of PET resin As a result, it was found that the bitterness value and astringency value can be lowered by the above-described method, and the above-described problem of producing an aromatic polyester resin that can withstand a tastefully advanced beverage can be achieved. However, it was found that the method of judging by the taste sensory test at the panelist could not solve the problem imposed by itself. Although this mechanism has many unclear points, it is considered as follows. In conventional pre-crystallization, crystallization, and solid phase polymerization with heat alone, the resin is heated from the surface and components related to subtle bitterness and astringency are volatilized from the surface of the resin, but the above components existing inside the resin are volatilized. It is estimated that subtle bitterness and astringency cannot be reduced because it cannot be performed.
Therefore, by heating the PET resin at various specific wavelengths using a near infrared heater in precrystallization, crystallization, and solid phase polymerization, the above components are volatilized from the inside of the resin by being heated from the inside of the resin. It is estimated that the bitterness value and astringency value could be lowered. Therefore, if such a mechanism can be achieved, it can be achieved by other methods, for example, a combination of far infrared rays, laser beams, and the like.
In the first stage precrystallization, the oxygen concentration is preferably 100 ppm or less, more preferably 50 ppm or less, even more preferably 30 ppm or less, and most preferably 20 ppm or less at a temperature of 100 to 180 ° C. for 1 minute. Heat treatment is performed for -5 hours. At this time, it is necessary to install a near infrared heater in the preliminary crystallization apparatus.
There is a relationship between the wavelength of the near infrared heater and the crystallinity of the aromatic polyester after the treatment. The wavelength of the near infrared heater is 1550 to 1800 nm, the preferred wavelength is 1600 to 1700 nm, and the most preferred wavelength is 1650 to 1680 nm. . When the wavelength is less than 1550 nm or exceeds 1800 nm, the surface crystallinity of the aromatic polyester chip does not increase to the following range.

Next, in the second and subsequent crystallization steps, the oxygen concentration is preferably 100 ppm or less, more preferably 50 ppm or less, even more preferably 30 ppm or less, and most preferably 20 ppm or less, at a temperature of 100 to 220 ° C. And heat treatment under conditions of 1 minute to 5 hours.
Furthermore, it is necessary to install a near-infrared heater in the second and subsequent crystallization apparatuses, and the wavelength of the near-infrared heater is 1450 nm to 1600 nm, preferably 1500 to 1550 nm. When the wavelength of near infrared rays is less than 1450 nm or exceeds 1600 nm, the bitterness and astringency when measured with a taste inspection apparatus are increased, and the flavor property is deteriorated.
The surface crystallinity of the chip after crystallization is set to 40 to 65%, preferably 45 to 63%, and more preferably 50 to 60%. If the surface crystallinity of the polymer is less than 40%, the solid phase polymerization temperature cannot be increased to 200 ° C. or higher, and low molecular weight oligomers that are thought to affect the flavor properties in the obtained solid phase polymerized polyester material. As described later, the inert gas discharged from the solid phase polymerization apparatus and purified by the purification apparatus is partially mixed with fresh inert gas and reused. Impurities in the inert gas are likely to be adsorbed on the surface of the polyester chip, both of which are problematic because they adversely affect flavor properties. On the other hand, if the degree of crystallinity exceeds 65%, the solid-phase polymerization rate becomes slow, resulting in a problem of poor economic efficiency.
When the crystallization apparatus is a one-stage facility, it is necessary to be able to irradiate the first half and the latter half separately with the infrared device as described above.
Note that the surface crystallinity of the chip can be obtained from DSC.
The crystallinity of the chip after crystallization is in the range of 30 to 60%, preferably 35 to 58%, more preferably 40 to 55%. The crystallinity can be obtained from the density of the chip.

Next, using a solid-state polymerization apparatus equipped with a near infrared heater, the melting is performed in an inert gas atmosphere with an oxygen concentration of preferably 100 ppm or less, more preferably 50 ppm or less, even more preferably 30 ppm or less, and most preferably 20 ppm or less. Solid state polymerization is carried out at an optimum temperature for the polycondensed polyester so that the increase in intrinsic viscosity by solid phase polymerization is 0.10 deciliter / gram or more. For example, the upper limit of the solid state polymerization temperature is preferably 215 ° C. or lower, more preferably 210 ° C. or lower, particularly preferably 208 ° C. or lower, and the lower limit is 190 ° C. or higher, preferably 195 ° C. or higher.
By using a near-infrared heater installed in a solid phase polymerization apparatus, the bitterness and astringency when measured with a taste inspection apparatus are improved, and flavor properties are improved. The preferred wavelength is 1450 to 1600 nm, and the more preferred wavelength is 1500 to 1550 nm. When the wavelength is less than 1450 nm or more than 1600 nm, the bitterness and astringency values according to the following bitterness and astringency tests are increased and flavor properties are increased. Gets worse.

  After the completion of the solid-phase polymerization, the chip temperature is about 70 ° C. or less, preferably 60 ° C. or less, more preferably within about 30 minutes, preferably within 20 minutes, more preferably within 10 minutes in the same inert gas atmosphere as described above. Is preferably cooled to about 50 ° C. or less.

  In addition, the inert gas used in the solid-phase polymerization is, for example, passed through a filtration device, a cooling device, an impurity removal device, a cleaning device, a heating device, etc. for removing solids such as fine-grained polymers and oligomers, This is replenished with fresh inert gas and circulated through the solid state polymerization apparatus.

  As a removal device or cleaning device for impurities in the inert gas, a cleaning device (for example, a scrubber) by liquid contact with the inert gas, an adsorption device for removing impurities in the inert gas, an inert gas combustion device, or the like Is mentioned.

  It has been found that the impurity concentration and oxygen concentration in the inert gas purified and recycled in this way affect the bitterness and astringency test measurement results. In order to accurately measure the concentration of impurities in an inert gas, a complicated operation and a complicated measuring device are required. However, a method of measuring the dew point of an inert gas with a dew point meter and using it as a substitute scale may be used. I can do it.

The dew point of the purified inert gas circulated in the solid phase polymerization apparatus is −50 ° C. or lower, preferably −55 ° C. or lower, more preferably −60 ° C. or lower, most preferably −65 ° C. or lower, and the inert gas after washing. The oxygen concentration therein is 100 ppm or less, preferably 50 ppm or less, particularly preferably 30 ppm or less, and most preferably 20 ppm or less. When the dew point of the inert gas after washing exceeds −50 ° C. and the oxygen concentration in the inert gas after washing exceeds 100 ppm, the bitterness and astringency test measurement results are poor, and flavor retention is not improved.
The purified inert gas contains 10 to 90% fresh inert gas, preferably 20 to 70%, more preferably 30 to 60%, particularly preferably 30 to 50%, most preferably from outside the system. Can be replenished by 35 to 50% to reduce the impurity concentration and oxygen concentration.
The dew point of the purified inert gas circulated in the solid phase polymerization apparatus is set to −50 ° C. or less, and the purified inert gas is replenished with 10% or more of the purified inert gas. Reducing the amount of impurities in the inert gas to be returned is important for improving the aromatic polyester flavor. It is presumed that impurities remaining in the inert gas are adsorbed on the surface of the polyester chip during the solid phase polymerization, and this affects the flavor properties.

  The aromatic polyester of the present invention is an aromatic polyester having a repeating unit consisting of an aromatic dicarboxylic acid component and a glycol component, and the molded article made of the aromatic polyester is extracted in ultrapure water at 80 ° C. for 1 hour. When the bitterness value and astringency value of the extracted water obtained by performing the treatment are measured with a taste inspection device equipped with a taste sensor made of an artificial lipid membrane, the bitterness value of the extracted water and the bitterness value of ultrapure water The difference and the difference between the astringency value of the extracted water and the astringency value of the ultrapure water are 0.5 or less, preferably 0.4 or less, more preferably 0.3 or less, respectively. In order to obtain the aromatic polyester of the present invention by, for example, a direct esterification method, it is achieved by satisfying the following conditions [1] to [4].

[1] Inert gas defined as follows is used in all processes from preparation and storage of terephthalic acid slurry to the end of the solid phase polymerization process, and process conditions such as oxygen concentration in the atmosphere of each reactor are as follows: The acid value is 5 to 45 equivalent / ton, the AA content is 100 ppm or less, the fluorescence emission intensity (B) is 15 or less, and the increase in the fluorescence emission intensity is 20 or less. A polycondensed polyester is obtained. The melt polycondensed polyester having the above-mentioned fluorescence characteristics can be obtained by chip-forming by melt polycondensation under the following process conditions.
1) An inert gas having an oxygen concentration of 5 ppm or less is circulated in the gas phase portion of the terephthalic acid slurry preparation tank and storage tank.
2) Maintain the oxygen concentration in the gas phase part of the terephthalic acid slurry preparation tank and storage tank at 100 ppm or less.
3) Pass an inert gas having an oxygen concentration of 5 ppm or less through ethylene glycol.
4) An inert gas having an oxygen concentration of 5 ppm or less is passed through the catalyst or phosphorus compound solution, and the inert gas is circulated in the gas phase portion.
5) An inert gas having an oxygen concentration of 5 ppm or less is passed through the gas phase portion of the esterification reactor.
6) The reaction temperature of the final reactor during the polycondensation reaction is maintained at 265 to 300 ° C.
7) Water that satisfies all of the following (1) to (5) is used as cooling water during chip formation.
Na ≦ 1.0 (ppm) (1)
Mg ≦ 1.0 (ppm) (2)
Si ≦ 2.0 (ppm) (3)
Ca ≦ 1.0 (ppm) (4)
COD ≤ 2.0 (mg / l) (5)
Moreover, the objective of this invention can be achieved more easily by adding the following methods.
8) Maintain the atmosphere in the terephthalic acid storage silo in an inert gas atmosphere with an oxygen concentration of 200 ppm or less.

[2] The moisture content of the melt polycondensed polyester chip is set to 3000 to 12000 ppm before precrystallization as a pretreatment for solid-phase polymerization, and then precrystallization is performed using a near infrared heater under the following conditions.
1) Heat treatment at a temperature of 100 to 180 ° C. for 1 minute to 5 hours in an inert gas atmosphere having an oxygen concentration of 100 ppm or less.
2) The wavelength of the near infrared heater is 1550 nm to 1800 nm.

[3] Further, in the second and subsequent crystallization steps, the crystallization treatment is further performed using the near-infrared heater under the above-described conditions, and the crystallinity of the chip surface is set to 40 to 65%.
1) Heat treatment at a temperature of 100 to 210 ° C. for 1 minute to 5 hours in an inert gas atmosphere having an oxygen concentration of 100 ppm or less.
2) The wavelength of the near infrared heater for crystallization is 1450 nm to 1600 nm.

[4] Next, solid phase polymerization is performed using a near infrared heater under the following conditions.
1) Heat treatment in an inert gas atmosphere with an oxygen concentration of 100 ppm or less at a temperature of 215 to 190 ° C. so that the increase in intrinsic viscosity due to solid-phase polymerization is 0.10 deciliter / gram or more.
2) The wavelength of the near infrared heater is 1450 nm to 1600 nm.
At this time, the used inert gas discharged from the solid phase polymerization reactor is purified by the above-described method, and the oxygen concentration of the inert gas atmosphere in the apparatus such as the solid phase polymerization reactor is within the regulation value. After mixing with a fresh inert gas, it is heated to a predetermined temperature and reused for solid phase polymerization.
In addition, although the wavelength of the lamp used for the near-infrared heater of each said term is ideal, the thing which has a certain distribution can be used from the surface of cost. It is preferable to have 50% or more, preferably 60% or more, of all wavelengths, and if it is less than 50%, the flavor property tends to be lowered.

The melt polycondensed polyester obtained as described above is crystallized and solid-phase polymerized by the above-described method, and in each step, the chip is heated near the above-mentioned atmosphere while being processed in the above-mentioned atmosphere. By irradiating with infrared rays, it is possible to obtain an aromatic polyester with improved flavor that can satisfy claim 1 of the present invention.
Although the causative substances related to bitterness and astringency measured when the aromatic polyester of the present invention is evaluated by the following bitterness and astringency tests have not been clearly confirmed, especially the near infrared rays as described above are used. It is estimated that the bitterness and astringency can be reduced by using.

  The intrinsic viscosity of the aromatic polyester of the present invention, particularly the aromatic polyester whose main repeating unit is composed of ethylene terephthalate, is preferably 0.55 to 1.50 deciliter / gram, more preferably 0.58 to 1.30. Deciliter / gram, more preferably in the range of 0.60-0.90 deciliter / gram. When the intrinsic viscosity is less than 0.55 deciliter / gram, the mechanical properties of the obtained molded article are poor. Also, if it exceeds 1.50 deciliters / gram, the resin temperature becomes high when melted by a molding machine or the like, resulting in severe thermal decomposition, increasing the number of free low molecular weight compounds that affect the fragrance retention, resulting in poor flavor. Problems such as yellowing of the polyester molded product tend to occur.

  In addition, the intrinsic viscosity of the aromatic polyester of the present invention, particularly the aromatic polyester in which the main repeating unit is composed of ethylene-2,6-naphthalate, is 0.40 to 1.00 deciliter / gram, preferably 0.42 to The range is 0.95 deciliter / gram, more preferably 0.45 to 0.90 deciliter / gram. When the intrinsic viscosity is less than 0.40 deciliter / gram, the mechanical properties of the obtained molded article and the like are poor. On the other hand, if it exceeds 1.00 deciliter / gram, the resin temperature becomes high when melted by a molding machine or the like, the thermal decomposition becomes severe, the amount of free low molecular weight compounds affecting the fragrance retention increases, and the polyester molded body becomes Problems such as yellow coloring occur.

  The intrinsic viscosity of the aromatic polyester of the present invention, particularly the aromatic polyester whose main structural unit is composed of 1,3-propylene terephthalate, is 0.50 to 2.00 deciliter / gram, preferably 0.55 to 1. The range is 50 deciliters / gram, more preferably 0.60 to 1.00 deciliter / gram. When the intrinsic viscosity is less than 0.50 deciliter / gram, the mechanical properties of the obtained molded article and the like are deteriorated, which is a problem. The upper limit of the intrinsic viscosity is 2.00 deciliters / gram, and if it exceeds this, the resin temperature becomes high at the time of melting by a molding machine or the like, resulting in severe thermal decomposition, drastically lowering the molecular weight, Problems such as yellow coloring occur.

The aromatic polyester of the present invention is a polyester composition comprising at least two aromatic polyesters having a difference in intrinsic viscosity of substantially the same composition in the range of 0.05 to 0.30 deciliter / gram. Also good.
The aromatic polyester of the present invention can be produced, for example, as described above, but is not limited thereto.

  The shape of the aromatic polyester chip of the present invention may be any of a cylinder shape, a square shape, a spherical shape, a flat plate shape, and the like. The average particle diameter is usually 1.0 to 4 mm, preferably 1.0 to 3.5 mm, and more preferably 1.0 to 3.0 mm. For example, in the case of a cylinder type, it is practical that the length is about 1.0 to 4 mm and the diameter is about 1.0 to 4 mm. In the case of spherical particles, it is practical that the maximum particle size is 1.1 to 2.0 times the average particle size and the minimum particle size is 0.7 times or more the average particle size. The weight of the chip is practically in the range of 2 to 50 mg / piece. In order to reduce residual organic impurities in the melt polycondensed polyester as much as possible in the precrystallization step, it is preferable to use a flat plate-like chip.

  The content of dialkylene glycol copolymerized in the aromatic polyester of the present invention is preferably 0.5 to 7.0 mol%, more preferably 1.0 to 0.5 mol% of the glycol component constituting the aromatic polyester. It is 6.0 mol%, More preferably, it is 1.0-5.0 mol%. When the amount of dialkylene glycol exceeds 7.0 mol%, the heat stability is deteriorated, the decrease in molecular weight at the time of molding becomes large, and the increase in the content of aldehydes becomes large. Further, in order to produce an aromatic polyester having a dialkylene glycol content of less than 0.5 mol%, it is necessary to select uneconomic production conditions as transesterification conditions, esterification conditions or polymerization conditions. Do not fit. Here, the dialkylene glycol copolymerized in the aromatic polyester is, for example, in the case of an aromatic polyester whose main structural unit is ethylene terephthalate, among diethylene glycols by-produced during production from ethylene glycol, which is glycol. In the case of an aromatic polyester having 1,3-propylene terephthalate as a main constituent unit, it is a diethylene glycol (hereinafter abbreviated as DEG) copolymerized with the aromatic polyester. Among di (1,3-propylene glycol) (or bis (3-hydroxypropyl) ether) by-produced from propylene glycol during production, di (1,3-propylene glycol ( Hereinafter referred to as DPG)) It is.

  And the amount of diethylene glycol copolymerized with the aromatic polyester of the present invention, particularly the aromatic polyester whose main repeating unit is composed of ethylene terephthalate is 1.0 to 5.0 mol of the glycol component constituting the aromatic polyester. %, Preferably 1.3 to 4.5 mol%, more preferably 1.5 to 4.0 mol%. When the amount of diethylene glycol exceeds 5.0 mol%, the thermal stability is deteriorated, the decrease in molecular weight becomes large at the time of molding, and the increase in the acetaldehyde content and the formaldehyde content becomes large. Moreover, when diethylene glycol content is less than 1.0 mol%, the transparency of the obtained polyester molded object worsens.

  The content of aldehydes such as acetaldehyde in the aromatic polyester of the present invention is 50 ppm or less, preferably 30 ppm or less, more preferably 10 ppm or less. When the aldehyde content exceeds 50 ppm, the effect of maintaining the flavor of the content of the polyester molded product from the aromatic polyester is deteriorated. These lower limits are 0.1 ppb due to manufacturing problems.

  Here, the aldehydes means that ethylene glycol is a glycol component such as an aromatic polyester whose main component unit is an aromatic polyester and an aromatic polyester whose main unit is ethylene-2,6-naphthalate. In the case of the aromatic polyester as the main component, it is acetaldehyde or formaldehyde, in the case of the aromatic polyester having 1,3-propylene terephthalate as the main structural unit, allyl aldehyde, and further, the aromatic having the main component as butylene terephthalate. In the case of polyester, it is butanal. However, in the case of an aromatic polyester mainly composed of butylene terephthalate, the aldehyde is mostly detected as tetrahydrofuran.

  In addition, when the aromatic polyester of the present invention is an aromatic polyester having ethylene terephthalate as a main repeating unit, and the polyester stretched molded body composed thereof is used as a material for a container for low flavor beverages such as mineral water, The acetaldehyde content of the aromatic polyester is 10 ppm or less, preferably 5 ppm or less, more preferably 4 ppm or less.

  The content of the cyclic ester oligomer of the aromatic polyester of the present invention is 70% or less, preferably 60% or less, more preferably 70% or less of the content of the cyclic ester oligomer contained in the melt polycondensation polyester prepolymer of the aromatic polyester. Is preferably 50% or less, particularly preferably 35% or less. Here, the aromatic polyester generally contains cyclic ester oligomers having various degrees of polymerization, but the cyclic ester oligomer referred to in the present invention is the most contained among the cyclic ester oligomers contained in the aromatic polyester. A cyclic ester oligomer having a large amount means a cyclic trimer in the case of an aromatic polyester having ethylene terephthalate as a main repeating unit.

  In the case of PET, which is a representative aromatic polyester having ethylene terephthalate as a main structural unit, the aromatic polyester has a cyclic trimer content of the melt polycondensed polyester prepolymer of about 1.0% by weight. The content of the cyclic trimer of the aromatic polyester of the present invention is 0.70% by weight or less, preferably 0.60% by weight or less, more preferably 0.50% by weight or less, particularly preferably 0.35% by weight. The following is preferable. The lower limit of the cyclic trimer content is 0.20% by weight or more, preferably 0.22% by weight or more, and more preferably 0.25% by weight or more from the viewpoint of economical production. In the case of molding a heat-resistant hollow molded article or the like from the aromatic polyester of the present invention, heat treatment is performed in a heating mold, but when the cyclic trimer content is 0.70% by weight or more, The adhesion of the oligomer to the surface of the heating mold increases rapidly, and the transparency of the obtained hollow molded article is very deteriorated.

Further, when the molded product molded from the aromatic polyester of the present invention is melted at a temperature of 290 ° C. for 60 minutes, the increase amount of the cyclic ester oligomer is preferably 0.30% by weight or less, more preferably 0.10% by weight. % Or less is preferable. If the increase amount of the cyclic ester oligomer when melted at a temperature of 290 ° C. for 60 minutes exceeds 0.40% by weight, the cyclic ester oligomer increases at the time of molding resin melting, and the die or degassing port of the extruder or molding machine The transparency of a hollow molded article or the like obtained by abrupt increase in oligomer adhesion and clogging to the surface or the like, or oligomer adhesion to the heated mold surface is extremely deteriorated.
An aromatic polyester in which the increase amount of the cyclic ester oligomer when melted at a temperature of 290 ° C. for 60 minutes is 0.40% by weight or less is a method of adjusting the amount of the metal compound used as a polycondensation catalyst, or The polycondensation catalyst remaining in the aromatic polyester can be produced by deactivation treatment.
Here, the increase amount of the cyclic ester oligomer when melted at a temperature of 290 ° C. for 60 minutes is the 3 mm thickness of the stepped molded plate obtained from the aromatic polyester by the molding method described in the “Measurement method” section below. This is the value obtained for the sample from the plate.

As a means for deactivating the polycondensation catalyst, a method of inactivating the polycondensation catalyst by mixing a phosphorus compound with the aromatic polyester and mixing and reacting in a molten state such as during molding.
As a method of blending a phosphorus compound with an aromatic polyester, a method of dry blending a phosphorus compound with the aromatic polyester or a method of mixing an aromatic polyester chip with an aromatic polyester master batch chip in which a phosphorus compound is melt-kneaded and blended After blending a predetermined amount of phosphorus compound into aromatic polyester, melt in an extruder or molding machine to inactivate the polycondensation catalyst, soak the chip in a phosphorous compound solution, especially phosphoric acid aqueous solution, master The method of adding as a batch is mentioned. These phosphorus compounds may be copolymerized with an aromatic polyester. Specifically, it is preferable to use an aromatic polyester masterbatch obtained by copolymerizing or blending a phosphorus compound as a phosphorus atom in an amount of 100 to 5000 ppm. By appropriately changing the amount of phosphorus atoms in the aromatic polyester masterbatch and the blending amount of the masterbatch, the amount of increase in the cyclic trimer when melted at 290 ° C. for 60 minutes can be controlled.
Examples of the phosphorus compound used include phosphoric acid compounds, phosphonic acid compounds, phosphinic acid compounds, phosphorous acid compounds, phosphonous acid compounds, and phosphinic acid compounds. Specific examples are the compounds described above, and these may be used alone or in combination of two or more.

Further, the aromatic polyester obtained as described above may be subjected to contact treatment with water, water vapor, or a water vapor-containing gas.
Examples of the contact treatment method using water include a method of immersing the aromatic polyester in water in a treatment tank and a method of applying water on these chips with a shower. The treatment time is 5 minutes to 2 days, preferably 10 minutes to 1 day, more preferably 30 minutes to 10 hours, and the water temperature is 20 to 180 ° C., preferably 40 to 150 ° C., more preferably 50 to 120 ° C. The water to be used is preferably water that satisfies at least one of the above (1) to (5), and more preferably water that satisfies all of (1) to (5).

  In the case where the aromatic polyester chip is contacted with water vapor or water vapor-containing gas for treatment, water vapor or water vapor-containing gas or water vapor-containing air at a temperature of 50 to 150 ° C., preferably 50 to 110 ° C., is preferably granular. The water is supplied in an amount of 0.5 g or more as water vapor per 1 kg of polyester, or the granular polyester and water vapor are brought into contact with each other. The contact between the thermoplastic polyester chip and the water vapor is usually carried out for 10 minutes to 2 days, preferably 20 minutes to 10 hours. The processing method may be either a continuous method or a batch method.

  Furthermore, the aromatic polyester of the present invention preferably contains 0.1 ppb to 50000 ppm of at least one resin selected from the group consisting of polyolefin resins and polyacetal resins. The blending ratio of the resin used in the present invention to the aromatic polyester is 0.1 ppb to 10000 ppm, preferably 0.3 ppb to 1000 ppm, more preferably 0.5 ppb to 100 ppm, still more preferably 1.0 ppb to 1 ppm, particularly Preferably, it is 1.0 ppb to 45 ppb. When the blending amount is less than 0.1 ppb, the crystallization speed becomes very slow and the crystallization of the plug part of the hollow molded body becomes insufficient. Therefore, if the cycle time is shortened, the shrinkage amount of the plug part is specified. Since it does not fall within the range of values, capping defects occur, and the stretched heat-fixed mold that forms a heat-resistant hollow molded body is heavily soiled, and when trying to obtain a transparent hollow molded body, the mold is frequently cleaned. There must be. On the other hand, if it exceeds 50000 ppm, the crystallization speed becomes high, and the crystallization of the plug portion of the hollow molded body becomes excessive, and the shrinkage amount of the plug portion does not fall within the specified value range, resulting in capping failure and the content. Leaking, or the unstretched molded body for hollow molded bodies is whitened, which makes normal stretching impossible.

Examples of the polyolefin resin blended in the aromatic polyester of the present invention include a polyethylene resin, a polypropylene resin, and an α-olefin resin. These resins may be crystalline or amorphous.
The production of the polyester composition blended with the polyolefin resin or the like in the present invention is a method in which the resin such as the polyolefin resin is directly added to the aromatic polyester and melt-kneaded so that the content thereof falls within the range, Alternatively, in addition to a conventional method such as a method of adding as a master batch and melt-kneading, the resin may be produced at the production stage of the aromatic polyester, for example, during melt polycondensation, immediately after melt polycondensation, immediately after precrystallization, solid phase In the polymerization, at any stage such as immediately after solid phase polymerization, or in the process from the completion of the production stage to the molding stage, it can be added directly as a granular material, or the aromatic polyester It is also possible to use a method of mixing chips by a method such as bringing the chip into contact with the resin member under flow conditions, or a method of melt-kneading after the contact treatment. Kill.

  Here, as a method of bringing the aromatic polyester chip into contact with the resin member under flow conditions, the aromatic polyester chip may be brought into collision contact with the member within the space where the resin member exists. Preferably, specifically, for example, a transport container in a manufacturing process such as immediately after melt polycondensation of an aromatic polyester, immediately after precrystallization, immediately after solid phase polymerization, or in a transport stage as a product of an aromatic polyester chip. At the time of filling and discharging, or at the time of injection of the molding machine at the molding stage of the aromatic polyester chip, a part of the pneumatic transportation piping, gravity transportation piping, silo, magnet part of the magnet catcher, etc. is made of the resin, Sticking the resin film, sheet, molded body, etc., or lining the resin, or stick-like or net-like in the transfer path By, for example placing the resin member and the like, and a method of transferring an aromatic polyester chips. The contact time of the aromatic polyester chip with the member is usually an extremely short time of about 0.01 seconds to several minutes, but a small amount of the resin can be mixed into the aromatic polyester.

  The aromatic polyester of the present invention includes polyamide, polyesteramide, low molecular weight amino group-containing compound, hydroxyl group-containing compound, hindered phenyl compound, hindered amine compound, benzotriazole compound, benzophenone as an aldehyde reducing agent. Compound, polyphenol compound, phosphorus stabilizer, sulfur stabilizer, alkali metal salt can be blended, preferably polyamide, benzophenone compound, polyesteramide, phosphorus stabilizer, low molecular weight amino group-containing compound , A hydroxyl group-containing compound, a benzophenone compound, a hindered phenyl compound, and a hindered amine compound can be blended. Most preferably, it is a polyamide, a polyesteramide, or a low molecular weight amino group-containing compound, and the haze of the obtained polyester molded article is good.

These polyamide compounds, low molecular weight amino group-containing compounds, hydroxyl group-containing compounds and other aldehyde reducing agents may be used alone or in admixture at an appropriate ratio.
The aldehyde reducing agent is, for example, used in an amount of 0.001 to 5 parts by weight, preferably 0.01 to 3 parts by weight, more preferably 0.1 to 2 parts by weight, based on 100 parts by weight of the aromatic polyester of the present invention. Can do.

  The aldehyde reducing agent can be blended by adding a predetermined amount of aldehyde reducing agent in any reaction stage from the production of the low-polymerization oligomer of the aromatic polyester to the production of the aromatic polyester polymer. For example, the aldehyde reducing agent may be added to a reactor such as an esterification reactor or a polycondensation reactor in an appropriate form such as a fine granule, powder, or melt, or from the reactor to a reactor in the next step. The aldehyde reducing agent or a mixture of the aromatic polyester and the aromatic polyester may be introduced in a molten state into a transport pipe for the reactant of the aromatic polyester. Furthermore, if necessary, the obtained chip can be subjected to solid phase polymerization in a high vacuum or in an inert gas atmosphere.

  Moreover, it can also obtain by the method of mixing an aromatic polyester and an aldehyde reducing agent by a conventionally well-known method, or the method of mixing an aldehyde reducing agent with the mixture of 2 or more types of aromatic polyesters. For example, a polyamide chip and two types of aromatic polyester chips with different IVs are dry blended with a tumbler, V-type blender, Henschel mixer, etc., and the dry blended mixture is mixed with a single screw extruder, twin screw extruder, kneader, etc. Examples include those obtained by melt mixing one or more times, and those obtained by subjecting chips from the melt mixture to solid phase polymerization under a high vacuum or an inert gas atmosphere as necessary.

  Further, a method in which a solution in which the polyamide or the like is dissolved in a solvent such as hexafluoroisopropanol is adhered to the surface of the aromatic polyester chip, and the aromatic polyester is used as the member in a space where the polyamide member is present. Examples include a method of causing the polyamide to adhere to the surface of the aromatic polyester chip by collision contact.

  The aromatic polyester of the present invention can be used to form sheet-like materials, biaxially stretched films, hollow molded bodies, trays and other packaging materials and non-woven fabrics using a commonly used melt molding method, or by a melt extrusion method. A coating can be formed on another substrate. In addition, the aromatic polyester of the present invention can be used as one constituent layer of a multilayer molded body, a multilayer film, or the like. It can also be used as a base material on which an oxygen barrier film such as carbon or silica is deposited.

  The method for producing a polyester molded body from the aromatic polyester of the present invention will be briefly described below by taking an aromatic polyester having ethylene terephthalate as a main repeating unit as an example, but is not limited thereto. The aromatic polyester of the present invention is a film formed by a generally used melt molding method after the moisture content is reduced to about 100 ppm or less, preferably 50 ppm or less by heat drying under vacuum or heat drying under an inert gas. Sheets, containers, other packaging materials, and non-woven fabrics can be formed.

  Here, the polyester molded body refers to a polyester molded body such as a sheet-like material or a cup-like material used as it is and the following polyester preform. A polyester preform is a preform obtained by compression molding an unstretched sheet-like material obtained by melt extrusion molding of an aromatic polyester or a melt mass obtained by melt extrusion molding, or injection molding. Is a preform obtained by the above. Further, it is a molded body that is melt-extruded and extruded into a pipe shape (so-called direct blow molded body), and then a cylindrical molded body that is further molded into a container, a cup-shaped molded body that is obtained by injection molding, Also included are molded products that are commercialized as containers by laminating paper and non-woven fabrics.

  Moreover, it is possible to improve mechanical strength by extending | stretching the sheet-like material which consists of aromatic polyester of this invention at least to a uniaxial direction. The stretched film composed of the aromatic polyester of the present invention is a sheet-like product obtained by injection molding or extrusion molding, and can be any one of uniaxial stretching, sequential biaxial stretching, and simultaneous biaxial stretching that are usually used for PET stretching. It is molded using a stretching method. Further, it can be formed into a cup shape or a tray shape by pressure forming or vacuum forming.

Below, the specific manufacturing method about the extending | stretching molded object in the case of PET is demonstrated easily.
In producing a stretched film, the stretching temperature is usually 80 to 130 ° C. Stretching may be uniaxial or biaxial, but biaxial stretching is preferred from the viewpoint of film physical properties. In the case of uniaxial stretching, the stretching ratio is usually 1.1 to 10 times, preferably 1.5 to 8 times. In the case of biaxial stretching, the longitudinal and transverse directions are usually 1.1 to 8 times, respectively. Preferably, it may be performed in a range of 1.5 to 5 times. The vertical / horizontal magnification is usually 0.5 to 2, preferably 0.7 to 1.3. The obtained stretched film can be further heat-set to improve heat resistance and mechanical strength. The heat setting is usually performed under tension at 120 to 240 ° C., preferably 150 to 230 ° C., usually for several seconds to several hours, preferably several tens of seconds to several minutes.

In producing a stretched hollow molded body, a foam molded from the aromatic polyester of the present invention is stretch blow molded, and a conventional apparatus used in PET blow molding can be used. Specifically, for example, once a preform is formed by injection molding or extrusion molding, the plug part and the bottom part are processed as it is, and then reheated, and then biaxial stretch blow molding such as hot parison method or cold parison method The law applies. The molding temperature in this case, specifically, the temperature of each part of the cylinder of the molding machine and the nozzle is usually in the range of 260 to 300 ° C.
The preferred polymer residence time is 120 seconds or less, more preferably 110 seconds or less, the most preferred residence time is 100 seconds or less, and if the polymer residence time exceeds 120 seconds, it is soluble in water that affects flavor properties. This is not preferable because the content of low molecular weight oligomers and AA tends to increase.
The stretching temperature is usually 70 to 120 ° C., preferably 90 to 110 ° C., and the stretching ratio is usually 1.5 to 3.5 times in the longitudinal direction and 2 to 5 times in the circumferential direction. The obtained hollow molded body can be used as it is, but in particular in the case of beverages that require hot filling, such as fruit juice beverages and oolong teas, in general, heat-setting treatment is performed in a blow mold, Used to impart sex. The heat setting is usually performed at 100 to 200 ° C., preferably 120 to 180 ° C. for several seconds to several hours, preferably several seconds to several minutes, under tension by compressed air or the like.

In addition, in order to impart heat resistance to the plug part, the plug part of the preform obtained by injection molding or extrusion molding is crystallized in a far-infrared or near-infrared heater installation oven, or after the bottle has been molded. The stopper is crystallized with the heater.
Moreover, the aromatic polyester of this invention can be used also for manufacture of the preform used for manufacture of the heat resistant bottle by the two-stage blow molding method provided with a primary blow molding process and a secondary blow molding process.

In the case of the two-stage blow molding method of PET, a preform obtained by crystallizing the plug portion as described above in the primary blow molding step is 1.0 to 1.0 to the final product volume at the same stretching temperature as described above. The biaxially stretched blow molding is performed about twice, and then the obtained primary molded body is heated at about 100 to 250 ° C. and then subjected to secondary blowing in a mold of about 80 to 200 ° C. in the secondary blow molding step.
The aromatic polyester of the present invention is also used for producing a stretched hollow molded body by a so-called compression molding method, in which a preform obtained by compression molding a molten mass cut after melt extrusion is stretch blow molded. Can do.
Another use of the aromatic polyester of the present invention is a film laminated on one or both sides of a laminated metal plate. Examples of the metal plate used include tinplate, tin-free steel, and aluminum.

As a laminating method, a conventionally known method can be applied, and it is not particularly limited. However, it is preferable to carry out by a thermal laminating method that can achieve organic solvent-free and avoid adverse effects on the taste and odor of food products due to residual solvent. In particular, the thermal laminating method by energization processing of a metal plate is particularly recommended. In the case of double-sided lamination, lamination may be performed simultaneously or sequentially.
Needless to say, a film can be laminated to a metal plate using an adhesive.

  Moreover, a metal container is obtained by shape | molding using the said laminated metal plate. The method for forming the metal container is not particularly limited. Further, the shape of the metal container is not particularly limited, but is preferably applied to a so-called two-piece can produced by a molding process such as drawing, drawing and ironing, and stretch draw molding. The present invention can also be applied to a so-called three-piece can in which a top cover suitable for filling a food product such as a coffee drink is wrapped to fill the contents.

In the aromatic polyester of the present invention, known ultraviolet absorbers, antioxidants, oxygen scavengers, lubricants added from the outside, lubricants precipitated internally during the reaction, mold release agents, nucleating agents, stability Various additives such as an agent, an antistatic agent, a bluing agent, a dye, and a pigment, and a polyamide resin from metaxylylenediamine and adipic acid may be added to improve oxygen permeability.
In addition, when the aromatic polyester of the present invention is used for a film application, calcium carbonate, magnesium carbonate, barium carbonate is included in the aromatic polyester in order to improve handling properties such as slipping property, winding property, and blocking resistance. , Inorganic particles such as calcium sulfate, barium sulfate, lithium phosphate, calcium phosphate, magnesium phosphate, organic salt particles such as terephthalate such as calcium oxalate, calcium, barium, zinc, manganese, magnesium, divinylbenzene, styrene, acrylic Inactive particles such as cross-linked polymer particles such as homo- or copolymers of acid, methacrylic acid, acrylic acid or methacrylic acid vinyl monomers can be included.

EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples.
The main characteristic value measurement methods will be described below.

(1) Intrinsic viscosity (IV) of polyester:
It calculated | required from the solution viscosity at 30 degreeC in a 1,1,2,2-tetrachloroethane / phenol (2: 3 weight ratio) mixed solvent.
(2) Diethylene glycol content of polyester (hereinafter referred to as [DEG content]):
The amount of DEG was decomposed with methanol and the amount of DEG was quantified by gas chromatography, and expressed as a ratio (mol%) to the total glycol components.

(3) Cyclic trimer in polyester (CT content):
300 mg of the frozen and ground sample is dissolved in 3 ml of a hexafluoroisopropanol / chloroform mixed solution (volume ratio = 2/3), and further diluted with 30 ml of chloroform. To this is added 15 ml of methanol to precipitate the polymer, followed by filtration. The filtrate was evaporated to dryness, made up to a constant volume with 10 ml of dimethylformamide, and the cyclic trimer was quantified by high performance liquid chromatography.

(4) Acetaldehyde content of polyester (hereinafter referred to as “AA content”):
Sample / distilled water = 1 gram / 2 cc of glass ampoule substituted with nitrogen was sealed and subjected to extraction treatment at 160 ° C for 2 hours. After cooling, acetaldehyde in the extract was measured by high-sensitivity gas chromatography. The concentration was expressed in ppm. In the case of a chip, the chip was used as it was.

(5) Increasing amount of cyclic trimer at the time of melting polyester (△ CT amount)
A sample was taken from a 3 mm-thick plate formed by the method described later, dried under reduced pressure at 140 ° C. and 0.1 mmHg or less for about 16 hours, and then 3 g of the sample was placed in a glass test tube and heated at 290 ° C. in a nitrogen atmosphere. Immerse in an oil bath for 60 minutes to melt. The increase amount of the cyclic trimer at the time of melting was determined by the following formula.
The cyclic trimer content of the plate was used as the cyclic trimer content before melting.
Increase amount of cyclic trimer at the time of melting (wt%) =
Cyclic trimer content after melting (wt%)-cyclic trimer content before melting (wt%)

(6) Free glycol content of polyester (hereinafter, free ethylene glycol content is referred to as “free EG content”, and free diethylene glycol content is referred to as “free DEG content”):
About 1.000 g of sample is precisely weighed and dissolved in 8 ml of a mixed solvent of hexafluoroisopropanol / chloroform (2/3) in an Erlenmeyer flask, and then 3 ml of distilled water is added to homogenize the contents. The mixed solvent was distilled off, and the residual aqueous phase was filtered using a glass fiber filter. The filtrate was made up to 10 ml with water and quantified by gas chromatography.
(7) Acid value After 0.1 g of polyester was dissolved in 10 ml of benzyl alcohol with heating, titration was performed using a 0.1N NaOH methanol / benzyl alcohol = 1/9 solution.

(8) Fluorescence emission intensity of polyester (B), increase amount of fluorescence emission intensity after heat treatment (B _h -B):
About 5-6 grams of sample chips taken out randomly are packed in a solid sample measurement cell (inner diameter 24.5 mm, height 12 mm), covered with a quartz glass plate, and a spectrofluorometer (Shimadzu Corporation) A spectrofluorometer (RF-540 type) manufactured by the manufacturer is attached. Fluorescence emitted by excitation light incident at an angle of 45 degrees is taken out in a perpendicular direction, introduced into a spectroscope, and a fluorescence spectrum having a vertical axis intensity of 0 to 100 is measured under the following conditions. FIG. 4 shows the fluorescence spectrum of PET.

As shown in FIG. 4, a distance L _B between the intersection (b) of the perpendicular line drawn from the point (a) of the spectrum at 450 nm to the tangent line is drawn on the low wave number side and the high wave number side of the obtained emission spectrum. (Mm) was measured, and the fluorescence emission intensity (B) was determined by the following equation. Next, the measured chip is taken out from the measurement cell and replaced with a new chip for measurement. Thus, it measures 5 times and calculates | requires an average value. In actual measurement, the peak at 395 nm and the peak at 450 nm may be shifted by several nm. In this case, the value of the spectrum peak is adopted, and when a clear peak is not recognized, values of 395 nm and 450 nm are adopted.
Fluorescence emission intensity (B) = (L _B / L) × 100
L (mm): length from fluorescent emission intensity 0 to 100 in spectrum diagram L _B (mm): length from (a) to (b) in spectrum diagram

Further, the fluorescence spectrum was measured in the same manner for the polyester chip heat-treated by the method described later, and the distance L _Bh (mm) between the intersection (b) of the perpendicular drawn from the point (a) of the spectrum at 450 nm to the tangent line The fluorescence emission intensity (B _h ) after the heat treatment is obtained in the same manner as described above, and then the increase amount (B _h -B) of the fluorescence emission intensity is obtained by the following equation. Measurement is performed five times by the same operation as described above, and an average value is obtained.
Increase amount of fluorescence emission intensity after heat treatment (B _h −B) =
Fluorescence emission intensity after heat treatment (B _h ) -fluorescence emission intensity before heat treatment (B)

Measurement condition:
ABSCISSA SCALE (horizontal axis): x2
ORDINATE SCALE ((vertical axis): × 4
SCAN SPEED (scanning speed): FAST
SENSITIVITY (Sensitivity): LOW
EXCITATION SLIT (excitation-side slit) (nm): 5
EMISION SLIT (slit on the light emission side) (nm): 5
EXCITATION WAVELENGTH (excitation light wavelength): 343 nm
EMISION START WAVELENGTH (emission start wavelength): 350 nm
EMISION END WAVELENGTH (emission end wavelength): 600 nm

(9) Heat treatment of polyester:
20 g of a sample vacuum-dried at about 80 ° C. for 8 hours at 10 torr or less is placed in a 100 ml glass container (mouth inner diameter 41 mm, trunk outer diameter 55 mm, total height 95 mm), and a gear type aging tester NH- manufactured by Nagano Scientific Machinery Co., Ltd. It was placed on a 202GT turntable and heat-treated at 180 ° C. for 10 hours in an air atmosphere.

(10) Moisture content of polyester (measured with Karl Fischer trace moisture measuring device CA-100 type and moisture vaporizer VA-100 manufactured by Mitsubishi Chemical)
A moisture vaporizer VA-100 manufactured by Mitsubishi Chemical was previously dried in two drying cylinders (filled with silica gel and phosphorus pentoxide), and the heating furnace was heated to 230 ° C. while flowing nitrogen gas at a flow rate of 250 ml / min. The sample board was put into a heating furnace, and after confirming that the dry nitrogen obtained from the heating furnace and the sample board was anhydrous with a trace moisture measuring device CA-100, 3 g of the sample was previously dried. Weigh accurately in a sample container and immediately place the sample on the sample board. The water vaporized from the sample is transported to a trace moisture measuring device CA-100 by dry nitrogen and subjected to Karl Fischer titration to determine the moisture content.

(11) Surface crystallinity of resin Measured with a differential thermal analyzer (DSC) manufactured by Seiko Denshi Kogyo Co., Ltd., RDC-220. Use a microtome to cut 0.1 mm from the resin surface and use 10 mg of sample. The temperature was raised at a rate of temperature rise of 20 ° C./min, and the crystallinity of the resin was determined from the calorimetric ratio of the crystallization peak and melting point peak observed in the middle.
(12) Molding of stepped molded plate:
As shown in FIG. 1 and FIG. 2, the polyester which has been vacuum-dried at 140 ° C. for about 16 hours using a vacuum dryer DP61 type manufactured by Yamato Science Co. 2 mm to 11 mm having a gate part (G) (A part thickness = 2 mm, B part thickness = 3 mm, C part thickness = 4 mm, D part thickness = 5 mm, E part thickness = 10 mm, F part thickness) A stepped molding plate having a thickness of (thickness = 11 mm) was injection molded.

In order to prevent moisture absorption during molding, the inside of the molding material hopper was purged with a dry inert gas (nitrogen gas). The plasticizing conditions of the M-150C-DM injection molding machine are: feed screw rotation speed = 70%, screw rotation speed = 120 rpm, back pressure 0.5 MPa, cylinder temperature 45 ° C., 250 ° C. from the bottom of the hopper in order, nozzle The temperature was set at 290 ° C. The injection conditions are 20% for the injection speed and pressure holding speed, and the injection pressure and pressure holding are adjusted so that the weight of the molded product is 146 ± 0.2 g. In this case, the pressure holding is 0.5 MPa relative to the injection pressure. Adjusted low.
The upper limit of the injection time and pressure holding time was set to 10 seconds and 7 seconds, respectively, and the cooling time was set to 50 seconds.
Although the temperature of the mold was constantly controlled by introducing cooling water having a water temperature of 10 ° C., the mold surface temperature at the time of molding stability was around 22 ° C.
The test plate for evaluating the molded product characteristics was arbitrarily selected from the 11th to 18th shots of the stable molded product after the molding material was introduced and the resin was replaced.
A plate having a thickness of 3 mm (part B in FIG. 1) was used for measuring the amount of increase in cyclic trimer (ΔCT amount) during melting, and a plate having a thickness of 5 mm (part D in FIG. 1) was used for measuring haze.

(13) Molding of preform:
Using the polyester dried in the same manner as described above, the temperature of the cylinder and the hot runner was set so that the resin temperature would be 290 ° C. using an M-150C-DM injection molding machine manufactured by Meiki Seisakusho, and the injection pressure was set to 1.8. A preform (outer diameter: 29.4 mm, length: 145.5 mm, wall thickness: about 3.7 mm, weight: 60 g) was molded under a condition of ˜2.3 kg / cm ^{2 and} a cycle time of 45 seconds. Molding was performed at a mold temperature of 13 ° C. (surface temperature around 17 ° C.) during molding stability.

(14) Molding of hollow molded body:
After the plug portion of the preform obtained in the above was crystallized by heating with an NC-01 plug portion crystallization apparatus manufactured by Frontea Co., Ltd. An axial stretch blow was performed, followed by heat setting in a mold set at about 150 ° C. for about 5 seconds to form a container having a capacity of 1500 cc. The stretching temperature was controlled at 100 ° C.

(15) Bitterness and astringency test:
Using the sample obtained by cutting the body portion of the preform obtained above to a size of about 10 mm, it was tested by the following method.
A 40 gram sample was placed in a glass container ultrasonically cleaned with ultrapure water, 300 ml of ultrapure water was added thereto, and then washed with an ultrasonic cleaner for 10 minutes.
Put 500 ml of ultrapure water into a 500 ml Erlenmeyer flask that has been ultrasonically cleaned and dried by adding ultrapure water, and put the above-mentioned molded product sample into it, followed by extraction treatment in a constant temperature bath at 80 ° C. for 1 hour. It was.
After treatment, take out the Erlenmeyer flask, let it stand at room temperature and cool to room temperature. Put the solution in the Erlenmeyer flask (300 ml) washed in the same way as above without foaming, and make sure that it does not make a headspace. The stopper was put, wound with VALQUA tape seal (manufactured by Yamato Scientific Co., Ltd., 0.1 mm thickness, 13 mm width fluorine tape), and stored in the refrigerator until the bitterness and astringency test. A sample of the molded body was handled with tweezers. Potassium chloride is added to the extraction water obtained by the above method and adjusted to 10 mMol%. Using “Taste Recognition Device SA402B” manufactured by Intelligent Sensor Technology, potassium chloride is added to ultrapure water and the adjusted product of 10 mMol% is measured as a blank. did. In particular, we focused on measurements with sensors that sense bitterness and astringency.
The ultrapure water was created using an ultrapure water production apparatus WR600G (manufactured by Yamato Scientific Co., Ltd.).

(16) Appearance of the hollow molded body:
Twenty hollow molded bodies from the tenth molding start (15) were visually observed and evaluated as follows.
◎: Transparent and no appearance problem △: No whitened flow pattern but opaque *: There is a little whitened flow pattern or whitened product on the hollow molded body XX: White molded flow pattern or whitened product on the hollow molded body

(17) Chemical oxygen demand (COD) (mg / l) of cooling water in the chip forming process:
The cooling water filtered with a 1G1 glass filter manufactured by Iwaki Glass Co., Ltd. was measured according to the method of JIS-K0101.

(18) Sodium content, calcium content, magnesium content and silicon content in the cooling water in the chip-forming process and the water introduced in the water treatment process:
Cooling water and introduced water after particle removal and ion exchange were collected and filtered through a 1G1 glass filter manufactured by Iwaki Glass Co., Ltd., and the filtrate was measured using an inductively coupled plasma emission spectrometer manufactured by Shimadzu Corporation.

(19) Measuring method of metal and phosphorus residual amount in polyester:
A sample piece was prepared by heating and melting the polyester to a melting point + 20 ° C. in a stainless steel circular ring having a thickness of 5 mm and an inner diameter of 50 mm. The amount of elements was determined by fluorescent X-ray analysis and displayed in ppm. In determining the amount, a calibration curve obtained in advance from a sample with a known amount of each element was used.
(20) Taste sensory test The body part of the preformed body obtained above was tested by the following method using a sample cut to a size of about 10 mm.
A 40 gram sample was placed in a glass container ultrasonically cleaned with ultrapure water, 300 ml of ultrapure water was added thereto, and then washed with an ultrasonic cleaner for 10 minutes.
Put 500 ml of ultrapure water into a 500 ml Erlenmeyer flask that has been ultrasonically cleaned and dried by adding ultrapure water, and put the above-mentioned molded product sample into it, followed by extraction treatment in a constant temperature bath at 80 ° C. for 1 hour. It was.
Remove the Erlenmeyer flask after treatment, let it stand at room temperature and cool it to room temperature. Put the solution into the Erlenmeyer flask (300 ml) washed as above without overflowing, without overflowing, and make no headspace with a ball stopper. The stopper was put, wound with a VALQUA tape seal (manufactured by Yamato Kagaku Co., Ltd., fluorine tape with a thickness of 0.1 mm and a width of 13 mm), and stored in the refrigerator until the taste sensory test. A sample of the molded body was handled with tweezers. After opening the sample obtained above, tests such as flavor and odor were performed. Use ultrapure water as a blank for comparison. The taste sensory test was conducted by 10 panelists according to the following criteria, and the average values were compared.
(Evaluation criteria)
◎: Feel no strange taste or smell ○: Feel a slight difference from the blank △: Feel a difference from the blank ×: Feel a considerable difference from the blank XX: Feel a very large difference from the blank

Example 1
A slurry of high-purity terephthalic acid and ethylene glycol stored in the slurry storage tank is continuously supplied to the first esterification reactor containing the reactants in advance after being prepared in the slurry preparation tank, and with stirring, The reaction was carried out at about 250 ° C. and 0.5 kg / cm ² G for an average residence time of 3 hours. This reaction product was sent to the second esterification reactor, and the reaction was carried out with stirring at about 260 ° C. and 0.05 kg / cm ² to a predetermined reactivity. Further, an ethylene glycol solution of crystalline germanium dioxide and an ethylene glycol solution of phosphoric acid were continuously supplied separately to the second esterification reactor. Nitrogen gas having an oxygen concentration of 1 ppm or less is circulated through these preparation tanks, storage tanks, and reactors, and the oxygen concentration in the gas phase of the slurry preparation tank is 30 ppm or less, and the first and second esterification reactions. The oxygen concentration in the gas phase of the vessel was kept below 30 ppm. Further, nitrogen gas having an oxygen concentration of about 1 ppm or less was bubbled through the prepared catalyst solution and phosphoric acid solution, and the same nitrogen gas was circulated through the catalyst solution tank and the phosphoric acid solution tank. The esterification reaction product is continuously fed to the first polycondensation reactor, and is stirred for about 1 hour at about 265 ° C. and 25 torr, and then stirred for about 2 hours at about 265 ° C. and 3 torr. The mixture was further subjected to polycondensation at about 275 ° C. and 0.5 to 1 torr with stirring in the final polycondensation reactor.
In addition, nitrogen gas with an oxygen concentration of 1 ppm or less was circulated through the atmosphere in the storage silo of high-purity terephthalic acid and stored in an inert gas atmosphere with an oxygen concentration of 10 ppm or less. In addition, an inert gas having an oxygen concentration of 1 ppm or less was aerated and stored in ethylene glycol in the storage tank.
The intrinsic viscosity of the melt polycondensation prepolymer is 0.57 dl / g, the acid value is 25 equivalents / t, the AA content is 50 ppm, the fluorescence emission intensity (B) is 3.2, and the increase in fluorescence emission intensity after heat treatment _(B h -B) was 5.7.

  The obtained melt polycondensation prepolymer was extruded from the pores into cooling water of about 20 ° C. having the following water quality and cut into water to form chips. Industrial water (derived from river underground water) was treated with a coagulation sedimentation device, filter filtration device, nitrogen gas blown heating deaerator, activated carbon adsorber and ion exchanger, sodium content was 0.07ppm, magnesium content was 0 .04 ppm, calcium content of 0.03 ppm, silicon content of 0.10 ppm, COD of 0.3 mg / l is introduced into the cooling water storage tank of the chipping process, and the discharged water from the chipping process After processing with a fine removal device whose filter medium is a paper-made 30 μm continuous filter and an activated carbon adsorption tower that adsorbs ethylene glycol and the like, return almost the entire amount to the cooling water storage tank and mix with the introduced water. Used as cooling water. While the cooling water is continuously circulated, the introduced water is replenished from the outside of the system and used as cooling water. The COD of the cooling water was 0.3 to 0.5 mg / l.

  Then, the melt polycondensation prepolymer having a fine content of about 100 ppm or less is removed for about 3 to 5 hours in a silo with an humidity of 80% by removing fines through a vibration sieving step and an airflow classification step. Then, the moisture content was set to 5000 ppm, and then supplied to a pre-crystallization apparatus with a near infrared heater having a wavelength of 1660 nm in a continuous solid-phase polymerization apparatus, and continuously at about 155 ° C. for 20 minutes in a nitrogen gas atmosphere having an oxygen concentration of 50 ppm or less. Crystallized preliminarily. Next, the resin is immediately sent to a crystallization apparatus with a near-infrared heater having a wavelength of 1500 nm, and continuously crystallized at about 155 ° C. for 3 hours in a nitrogen gas atmosphere having an oxygen concentration of 50 ppm or less, so that the chip surface crystallinity is 52%. Then, it was put into a tower-shaped 1500 nm wavelength solid-phase polymerization apparatus equipped with a near-infrared heater and continuously solid-phase polymerized at about 208 ° C. in a nitrogen gas atmosphere with an oxygen concentration of 50 ppm or less to obtain a solid-state polymerization polyester resin. After the solid phase polymerization, it was continuously processed in a sieving step and a fine removal step. Note that nitrogen gas having an oxygen concentration of 1 ppm was passed through the seal portions of the stirrers of the melt polycondensation reactor and the solid phase polymerization reactor.

In addition, the nitrogen gas used in the solid phase polymerization is cooled after solids are removed, and is cleaned by gas-liquid contact with cold ethylene glycol in a scrubber, and the nitrogen gas thus washed is replenished with new nitrogen gas, This is preheated and supplied to the solid phase polymerization reaction tower. At this time, in the scrubber, the gas / liquid ratio of used nitrogen gas / cleaning ethylene glycol and the replenishment ratio of new ethylene glycol to the cleaning ethylene glycol in the scrubber were within an appropriate range.
The dew point of nitrogen gas after washing with a scrubber was −50 ° C. or lower. Further, 10% fresh nitrogen gas was supplied to the nitrogen gas after washing, and the oxygen concentration in the nitrogen gas supplied to the solid phase polymerization apparatus was 50 ppm or less.
The oxygen concentration in the nitrogen gas was measured by a united analyzer type 310 manufactured by Teledyne Analytical Instruments, and the dew point was measured by a high-grotech MMY150 low dew point meter manufactured by Toyo Technica.

Thus, the intrinsic viscosity is 0.76 deciliter / gram, the DEG content is 2.6 mol%, the AA content is 2.7 ppm, the cyclic trimer content is 0.32 wt%, and the cyclic 3 content. The body gain was 0.40% by weight, and the fine content was about 100 ppm. Further, the Ge residual amount measured by fluorescent X-ray analysis was 45 ppm, and the P residual amount was 26 ppm.
About this PET, evaluation by the shaping | molding board obtained by the said method and a hollow molded object was implemented. The results are shown in Table 1.
The bitterness and bitterness of the bitterness test were as low as 0.3 and the bitterness was as low as 0.4. Furthermore, there was no problem in the taste sensory test using a panel.

(Example 2)
The PET of Example 1 was continuously charged from the supply port (1) at the top of the treatment tank to the following water treatment tank controlled at a treatment water temperature of 95 ° C. at a rate of 50 kg / hour, and the water was treated. A PET chip was continuously extracted from the outlet (3) with treated water at a rate of 50 kg / hour. The sodium content in the introduced water collected before the ion exchange water inlet (9) of the water treatment device is 0.02 ppm, the magnesium content is 0.05 ppm, the calcium content is 0.05 ppm, and the silicon content is 0.00. The concentration was 07 ppm and the COD was 0.4 mg / l. After the water treatment, fines and the like were removed. The results are shown in Table 1.
For water treatment of polyester chips, the apparatus shown in FIG. 3 is used. The raw material chip supply port (1) at the upper part of the treatment tank, the overflow discharge port (2) located at the upper limit level of the treatment water in the treatment tank, the lower part of the treatment tank A discharge port (3) for the mixture of polyester chip and treated water, treated water discharged from the overflow discharge port, treated water discharged from the treatment tank, and draining device discharged from the discharge port at the bottom of the treatment tank ( 4) The treated water passed through 4) is again sent to the water treatment tank through the fine powder removing device (5) whose filter medium is a paper-made continuous filter. A tower-type treatment tank having an internal capacity of about 50 m ³ equipped with a mouth (7), an adsorption tower (8) for adsorbing acetaldehyde in treated water after fine powder removal, and a new ion-exchange water inlet (9) was used. .

Example 3
PET was obtained by reacting in the same manner as in Example 1 except that an ethylene glycol solution of antimony trioxide, an ethylene glycol solution of cobalt acetate, and an ethylene glycol solution of phosphoric acid were used as the polycondensation catalyst. Of course, nitrogen gas having an oxygen concentration of about 1 ppm or less was bubbled through the prepared catalyst solution and phosphoric acid solution, and the same nitrogen gas was circulated through the catalyst solution tank and the phosphoric acid solution tank. The residual amount of Sb measured by X-ray fluorescence analysis was 180 ppm, the residual amount of Co was 15 ppm, and the residual amount of P was 10 ppm. The results are shown in Table 1.

Example 4
As the polycondensation catalyst, the reaction was carried out in the same manner as in Example 1 except that an ethylene glycol solution of basic aluminum acetate, Irganox 1222 (manufactured by Ciba Specialty Chemicals) and an ethylene glycol solution in which ethylene glycol was previously heated were used. PET was obtained and evaluated in the same manner as in Example 1. Of course, nitrogen gas having an oxygen concentration of about 1 ppm or less was bubbled through the prepared catalyst solution and the like, and the same nitrogen gas was passed through the catalyst solution tank and the phosphoric acid solution tank. The residual amount of Al measured by fluorescent X-ray analysis was 18 ppm, and the residual amount of P was 44 ppm. The results are shown in Table 1.

(Example 5)
The PET obtained in Example 4 was treated with water in the same manner as in Example 2, and evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Example 6)
PET was obtained by reacting in the same manner as in Example 1 except that an ethylene glycol solution of titanium tetrabutoxide was used as the polycondensation catalyst, and evaluation was performed in the same manner as in Example 1. Of course, nitrogen gas having an oxygen concentration of about 1 ppm or less was bubbled through the prepared catalyst solution, and the same nitrogen gas was passed through the catalyst solution tank. The residual amount of Ti measured by fluorescent X-ray analysis was 4 ppm. The results are shown in Table 1.

(Example 7)
As the polycondensation catalyst, PET was obtained by reacting in the same manner as in Example 1 except that ethylene glycol solution of ethyl acid phosphate, ethylene glycol solution of titanium tetrabutoxide, and ethylene glycol solution of magnesium acetate tetrahydrate were used. Evaluation was performed in the same manner as in Example 1.
Of course, nitrogen gas having an oxygen concentration of about 1 ppm or less was bubbled through the prepared catalyst solution, and the same nitrogen gas was passed through the catalyst solution tank. The residual amount of Ti measured by fluorescent X-ray analysis was 5 ppm, the residual amount of P was 24 ppm, and the residual amount of Mg was 30 ppm. The results are shown in Table 1.

(Example 8)
As a polycondensation catalyst, PET was obtained by reacting in the same manner as in Example 1 except that an ethylene glycol suspension of C94 (Ti: Si = 90: 10 mol / mol) manufactured by Akzo Nobel was used. Evaluation was performed in the same manner. Of course, nitrogen gas having an oxygen concentration of about 1 ppm or less was bubbled through the prepared catalyst solution, and the same nitrogen gas was passed through the catalyst solution tank. The residual amount of Ti measured by fluorescent X-ray analysis was 5 ppm. The results are shown in Table 2.

Example 9
A mixture of terephthalic acid / isophthalic acid = 98.5 parts / 1.5 parts by weight was used as a raw material, and an ethylene glycol solution of antimony trioxide, an ethylene glycol solution of cobalt acetate, and an ethylene glycol solution of phosphoric acid were used as a polycondensation catalyst. A PET was obtained by reacting in the same manner as in Example 1 except that the solid-state polymerization temperature was 203 ° C., and evaluated in the same manner as in Example 1. Of course, nitrogen gas having an oxygen concentration of about 1 ppm or less was bubbled through the prepared catalyst solution and the like, and the same nitrogen gas was passed through the catalyst solution tank and the phosphoric acid solution tank. The residual amount of Sb measured by X-ray fluorescence analysis was 180 ppm, the residual amount of P was 20 ppm, and the residual amount of Co was 15 ppm. The results are shown in Table 2.

(Example 10)
A slurry of high-purity terephthalic acid and ethylene glycol stored in a slurry storage tank is continuously supplied to a first esterification reactor containing a reactant in advance after being prepared in a slurry preparation tank, and stirred, The reaction was carried out at an average residence time of 2.0 hours at about 250 ° C. and 0.5 kg / cm ² G. This reaction product was sent to the second esterification reactor, and the reaction was carried out with stirring at about 260 ° C. and 0.05 kg / cm ² to a predetermined reactivity. Further, an ethylene glycol solution of crystalline germanium dioxide and an ethylene glycol solution of phosphoric acid were continuously supplied separately to the second esterification reactor. Nitrogen gas having an oxygen concentration of 1 ppm or less is circulated through these preparation tanks, storage tanks, and reactors, and the oxygen concentration in the gas phase of the slurry preparation tank is 30 ppm or less, and the first and second esterification reactions. The oxygen concentration in the gas phase of the vessel was kept below 30 ppm. Further, nitrogen gas having an oxygen concentration of about 1 ppm or less was bubbled through the prepared catalyst solution and phosphoric acid solution, and the same nitrogen gas was circulated through the catalyst solution tank and the phosphoric acid solution tank. The esterification reaction product is continuously fed to the first polycondensation reactor, and is stirred for about 1 hour at about 265 ° C. and 25 torr, and then stirred for about 2 hours at about 265 ° C. and 3 torr. The mixture was further subjected to polycondensation at about 275 ° C. and 0.5 to 1 torr with stirring in the final polycondensation reactor. The intrinsic viscosity of the melt polycondensation prepolymer is 0.57 dl / g, the acid value is 40 equivalents / t, the AA content is 40 ppm, the fluorescence emission intensity (B) is 3.5, and the increase in fluorescence emission intensity after heat treatment (B _h -B) was 4.5.
In the same manner as in Example 1, nitrogen gas having an oxygen concentration of 1 ppm or less was circulated through the atmosphere in the high-purity terephthalic acid storage silo and stored in an inert gas atmosphere having an oxygen concentration of 10 ppm or less. In addition, an inert gas having an oxygen concentration of 1 ppm or less was aerated and stored in ethylene glycol in the storage tank.

  The obtained melt polycondensation prepolymer was extruded from the pores into cooling water of about 20 ° C. having the following water quality and cut into water to form chips. Industrial water (derived from river underground water) was treated with a coagulation sedimentation device, filter filtration device, nitrogen gas blown heating deaerator, activated carbon adsorber and ion exchanger, sodium content was 0.07ppm, magnesium content was 0 .04 ppm, calcium content of 0.03 ppm, silicon content of 0.10 ppm, COD of 0.3 mg / l is introduced into the cooling water storage tank of the chipping process, and the discharged water from the chipping process After processing with a fine removal device whose filter medium is a paper-made 30 μm continuous filter and an activated carbon adsorption tower that adsorbs ethylene glycol and the like, return almost the entire amount to the cooling water storage tank and mix with the introduced water. Used as cooling water. While the cooling water is continuously circulated, the introduced water is replenished from the outside of the system and used as cooling water. The COD of the cooling water was 0.3 to 0.5 mg / l.

Next, the fine poly is removed by a vibration sieving step and an airflow classification step, whereby the melt polycondensation prepolymer having a fine content of about 100 ppm or less is placed in a silo having a nitrogen atmosphere with an oxygen concentration of 50 ppm or less and a humidity of 90%. Store for about 8 hours to make the water content 12000 ppm, then supply it to a pre-crystallization device with a near infrared heater with a wavelength of 1660 nm in a continuous solid-phase polymerization device and about 155 ° C. in a nitrogen gas atmosphere with an oxygen concentration of 50 ppm or less. For 20 minutes continuously. Next, the resin is immediately sent to a crystallization apparatus with a near-infrared heater having a wavelength of 1500 nm, and continuously crystallized at about 155 ° C. for 3 hours in a nitrogen gas atmosphere having an oxygen concentration of 50 ppm or less, so that the chip surface crystallinity is 53%. Then, it was placed in a tower-type 1500 nm wavelength solid-phase polymerization vessel equipped with a near-infrared heater, and continuously solid-phase polymerized at about 208 ° C. in a nitrogen gas atmosphere having an oxygen concentration of 50 ppm or less to obtain a solid-state polymerization polyester resin. After solid-phase polymerization, it was continuously processed in a sieving step and a fine removal step.
Note that nitrogen gas having an oxygen concentration of 1 ppm was passed through the seal portions of the stirrers of the melt polycondensation reactor and the solid phase polymerization reactor.

In addition, the nitrogen gas used in the solid phase polymerization is cooled after solids are removed, and is cleaned by gas-liquid contact with cold ethylene glycol in a scrubber, and the nitrogen gas thus washed is replenished with new nitrogen gas, This is preheated and supplied to the solid phase polymerization reaction tower. At this time, in the scrubber, the gas / liquid ratio of used nitrogen gas / cleaning ethylene glycol and the replenishment ratio of new ethylene glycol to the cleaning ethylene glycol in the scrubber were within an appropriate range.
The dew point of nitrogen gas after washing with a scrubber was −60 ° C. or lower. Further, the nitrogen gas after cleaning was supplemented with 50% fresh nitrogen gas, and the oxygen concentration in the nitrogen gas supplied to the solid phase polymerization apparatus was 30 ppm or less.
The oxygen concentration in the nitrogen gas was measured by a united analyzer type 310 manufactured by Teledyne Analytical Instruments, and the dew point was measured by a high-grotech MMY150 low dew point meter manufactured by Toyo Technica.

Thus, the intrinsic viscosity is 0.75 deciliter / gram, the DEG content is 2.5 mol%, the AA content is 3.0 pm, the cyclic trimer content is 0.32 wt%, and the cyclic 3 content. The body gain was 0.40% by weight, and the fine content was about 100 ppm. Further, the Ge residual amount measured by fluorescent X-ray analysis was 45 ppm, and the P residual amount was 26 ppm.
About this PET, evaluation by the shaping | molding board obtained by the method of said (9) and (10) and a hollow molded object was implemented. The results are shown in Table 2.
The bitterness and bitterness of the bitterness test were as low as 0.4 and the bitterness was as low as 0.3. Furthermore, there was no problem in the taste sensory test using a panel.

(Example 11)
A slurry of high-purity terephthalic acid and ethylene glycol stored in the slurry storage tank is continuously supplied to the first esterification reactor containing the reactants in advance after being prepared in the slurry preparation tank, and with stirring, The reaction was carried out at about 250 ° C. and 0.5 kg / cm ² G for an average residence time of 3 hours. This reaction product was sent to the second esterification reactor, and the reaction was carried out with stirring at about 260 ° C. and 0.05 kg / cm ² to a predetermined reactivity. Further, an ethylene glycol solution of crystalline germanium dioxide and an ethylene glycol solution of phosphoric acid were continuously supplied separately to the second esterification reactor. Nitrogen gas having an oxygen concentration of 1 ppm or less is circulated through these preparation tanks, storage tanks, and reactors, and the oxygen concentration in the gas phase of the slurry preparation tank is 30 ppm or less, and the first and second esterification reactions. The oxygen concentration in the gas phase of the vessel was kept below 30 ppm. Further, nitrogen gas having an oxygen concentration of about 1 ppm or less was bubbled through the prepared catalyst solution and phosphoric acid solution, and the same nitrogen gas was circulated through the catalyst solution tank and the phosphoric acid solution tank. The esterification reaction product is continuously fed to the first polycondensation reactor, and is stirred for about 1 hour at about 265 ° C. and 25 torr, and then stirred for about 2 hours at about 265 ° C. and 3 torr. The mixture was further subjected to polycondensation at about 275 ° C. and 0.5 to 1 torr with stirring in the final polycondensation reactor.
The intrinsic viscosity of the melt polycondensation prepolymer is 0.57 dl / g, the acid value is 25 equivalents / t, the AA content is 50 ppm, the fluorescence emission intensity (B) is 3.2, and the increase in fluorescence emission intensity after heat treatment (
B _h -B) was 5.7.
In the same manner as in Example 1, nitrogen gas having an oxygen concentration of 1 ppm or less was circulated through the atmosphere in the high-purity terephthalic acid storage silo and stored in an inert gas atmosphere having an oxygen concentration of 10 ppm or less. In addition, an inert gas having an oxygen concentration of 1 ppm or less was aerated and stored in ethylene glycol in the storage tank.

  The obtained melt polycondensation prepolymer was extruded from the pores into cooling water of about 20 ° C. having the following water quality and cut into water to form chips. Industrial water (derived from river underground water) was treated with a coagulation sedimentation device, filter filtration device, nitrogen gas blown heating deaerator, activated carbon adsorber and ion exchanger, sodium content was 0.07ppm, magnesium content was 0 .04 ppm, calcium content of 0.03 ppm, silicon content of 0.10 ppm, COD of 0.3 mg / l is introduced into the cooling water storage tank of the chipping process, and the discharged water from the chipping process After processing with a fine removal device whose filter medium is a paper-made 30 μm continuous filter and an activated carbon adsorption tower that adsorbs ethylene glycol and the like, return almost the entire amount to the cooling water storage tank and mix with the introduced water. Used as cooling water. While the cooling water is continuously circulated, the introduced water is replenished from the outside of the system and used as cooling water. The COD of the cooling water was 0.3 to 0.5 mg / l.

Then, the melt polycondensation prepolymer having a fine content of about 100 ppm or less is removed for about 3 to 5 hours in a silo with a humidity of 70% by removing fines by a vibration sieving step and an airflow classification step. The moisture content was set to 3000 ppm, and then supplied to a continuous crystallization apparatus equipped with a near-infrared heater with a near-infrared heater at a wavelength of 1660 nm and continuously for 20 minutes at about 155 ° C. in a nitrogen gas atmosphere having an oxygen concentration of 50 ppm or less. Crystallized preliminarily. Next, the resin is immediately sent to a crystallization apparatus with a near-infrared heater having a wavelength of 1500 nm, and continuously crystallized at about 155 ° C. for 3 hours in a nitrogen gas atmosphere having an oxygen concentration of 50 ppm or less, so that the chip surface crystallinity is 52%. Then, it was put into a tower-shaped 1500 nm wavelength solid-phase polymerization apparatus equipped with a near-infrared heater and continuously solid-phase polymerized at about 208 ° C. in a nitrogen gas atmosphere with an oxygen concentration of 50 ppm or less to obtain a solid-state polymerization polyester resin. After solid-phase polymerization, it was continuously processed in a sieving step and a fine removal step.
Note that nitrogen gas having an oxygen concentration of 1 ppm was passed through the seal portions of the stirrers of the melt polycondensation reactor and the solid phase polymerization reactor.

In addition, the nitrogen gas used in the solid phase polymerization is cooled after solids are removed, and is cleaned by gas-liquid contact with cold ethylene glycol in a scrubber, and the nitrogen gas thus washed is replenished with new nitrogen gas, This is preheated and supplied to the solid phase polymerization reaction tower. At this time, in the scrubber, the gas / liquid ratio of used nitrogen gas / cleaning ethylene glycol and the replenishment ratio of new ethylene glycol to the cleaning ethylene glycol in the scrubber were within an appropriate range.
The dew point of nitrogen gas after washing with a scrubber was −50 ° C. or lower. Further, 10% fresh nitrogen gas was supplied to the nitrogen gas after washing, and the oxygen concentration in the nitrogen gas supplied to the solid phase polymerization apparatus was 50 ppm or less.
The oxygen concentration in the nitrogen gas was measured by a united analyzer type 310 manufactured by Teledyne Analytical Instruments, and the dew point was measured by a high-grotech MMY150 low dew point meter manufactured by Toyo Technica.
Evaluation was performed in the same manner as in Example 1. The results are shown in Table 2.

(Example 12)
Example 1 except that the oxygen concentration in the atmosphere in the terephthalic acid storage silo is maintained at about 1000 ppm, and the oxygen concentration in the nitrogen gas atmosphere of the preliminary crystallization device, the crystallization device, and the solid phase polymerization device is 90 ppm or less. Evaluation of was carried out. The results are shown in Table 2.

(Examples 13 and 14)
The PET prepolymer obtained in Example 1 was treated and evaluated in the same manner as in Example 1 except that the crystallization conditions were changed to change the surface crystallinity of the chip. The results are shown in Table 2.
(Examples 15 and 16, Comparative Examples 1, 2, and 3)
Evaluation was performed after the trial manufacture in the same manner as in Example 1 except that the wavelength of the near-infrared lamp of the preliminary crystallization apparatus in Example 1 was changed. The results are shown in Tables 3 and 4.

(Comparative Example 4)
Nitrogen gas bubbling during preparation of polycondensation catalyst solution and phosphoric acid solution and nitrogen gas flow to both solution tanks are stopped, and nitrogen gas is not circulated in the reaction tank from the raw material preparation tank to the esterification reaction (these reactors (The oxygen concentration in the gas phase of 1000 ppm or more), nitrogen gas is not allowed to flow into the seal part of the reactor stirrer, the final polycondensation reaction temperature is 305 ° C, and the tip cooling water is about 13 to 15 ° C industrial water In the same manner as in Example 1 except that is used as it is, the intrinsic viscosity is 0.60 dl / g, the acid value is 47 equivalents / t, the DEG content is 5.7 mol%, and the AA content is 230 ppm. A prepolymer having a fluorescence emission intensity (B) of 37 and an increase in fluorescence emission intensity after heat treatment (B _h -B) of 30 was obtained.
The industrial water used for cooling at the time of chip formation is about 60000-80000 particles / 10 ml of particles having a particle size of 1-25 μm, a sodium content of 3.5-5.5 ppm, and a magnesium content of 0.8-1. 5 ppm, calcium content is 2.0 to 2.5 ppm, silicon content is 3.0 to 4.5 ppm, COD is 4.5 to 6.8 mg / l. It was 7000 ppm.

The prepolymer was allowed to stand in a dried atmosphere for about 1 month, then the moisture content of the polyester was adjusted to 2000 ppm, and the chip surface crystallinity after crystallization was set to 35%, as in Example 1. In this way, it was supplied to a continuous solid phase polymerization apparatus to carry out solid phase polymerization (solid phase polymerization time was shortened from that in Example 1). A near-infrared lamp was not installed in the preliminary crystallization apparatus, the crystallization apparatus, and the solid phase polymerization apparatus, and the oxygen concentration in the nitrogen gas atmosphere of these apparatuses was about 400 to 1000 ppm.
A PET having an intrinsic viscosity of 0.72 deciliter / gram, a DEG content of 5.7 mol%, a cyclic trimer content of 0.72 wt%, and an AA content of 18.9 pm was obtained. Further, the residual amount of Ge measured by fluorescent X-ray analysis was 45 ppm, and the residual amount of P was 30 ppm.
The gas / liquid ratio of used nitrogen gas / cleaning ethylene glycol in the scrubber is 1/100 of Example 1, the replenishment ratio of new ethylene glycol to the cleaning ethylene glycol in the scrubber is 1/300 of Example 1, and the cleaning ethylene The glycol temperature was about 20 ° C. higher than in Example 1.
Only 0.5% fresh nitrogen gas is replenished to the nitrogen gas after cleaning, the oxygen concentration in the nitrogen gas after cleaning supplied to the solid phase polymerization apparatus is 400 to 700 ppm, and the nitrogen gas after cleaning The dew point was 0 ° C. The results are shown in Table 4.

(Comparative Example 5)
PET was obtained by reacting in the same manner as in Example 1 except that the oxygen concentration in the nitrogen gas atmosphere of the preliminary crystallization apparatus, the crystallization apparatus, and the solid phase polymerization apparatus in the solid phase polymerization step was changed to 150 ppm. It was evaluated in the same manner as above. The results are shown in Table 4.

(Comparative Example 6)
Nitrogen gas bubbling during preparation of polycondensation catalyst solution and phosphoric acid solution and nitrogen gas flow to both solution tanks are stopped, and nitrogen gas is not circulated in the reaction tank from the raw material preparation tank to the esterification reaction (these reactors (The oxygen concentration in the gas phase of 1000 ppm or more), nitrogen gas is not allowed to flow to the seal of the reactor stirrer, the final polycondensation reaction temperature is 290 ° C, and the tip cooling water is about 13 to 15 ° C industrial water (The number of particles having a particle diameter of 1 to 25 μm and the content of metals such as sodium are substantially the same as those in Comparative Example 4) The melt polycondensation is performed in the same manner as in Example 1 except that the intrinsic viscosity is 0.56 dl / g, acid value is 49 equivalent / t, DEG content is 2.5 mol%, AA content is 120 ppm, fluorescence emission intensity (B) fluorescence intensity is 19, increase amount of fluorescence emission intensity after heat treatment (B _h -B) 23 pre A polymer was obtained.
After leaving this prepolymer in a dry air atmosphere for about one month, the moisture content of the polyester is adjusted to 2000 ppm, and the oxygen concentration in the nitrogen atmosphere of the precrystallization apparatus, the crystallization apparatus and the solid phase polymerization apparatus is adjusted. Was supplied to a continuous solid phase polymerization apparatus in the same manner as in Example 1 except that the content was changed to 300 to 500 ppm. The oxygen concentration in the nitrogen gas supplied to the solid phase polymerization apparatus was 300 to 900 ppm.
A PET having an intrinsic viscosity of 0.76 deciliter / gram, a DEG content of 2.5 mol%, a cyclic trimer content of 0.35 wt%, and an AA content of 14.9 ppm was obtained. The results are shown in Table 4.

(Comparative Example 7)
In the same manner as in Comparative Example 6, melt polycondensation was performed, the intrinsic viscosity was 0.57 dl / g, the acid value was 48 equivalents / t, the DEG content was 2.5 mol%, the AA content was 70 ppm, and the fluorescence emission intensity ( B) A prepolymer having a fluorescence intensity of 19 and an increase in fluorescence emission intensity after heat treatment (B _h -B) of 27 was obtained.
Subsequently, fines are removed by a vibration sieving step and an airflow classification step to reduce the fine content to about 100 ppm or less, and then pre-crystallization and crystallization are performed in the same manner as in Example 1 (nitrogen gas atmosphere). The oxygen concentration in the atmosphere was 50 ppm or less), and then solid phase polymerization was performed in an atmosphere having an oxygen concentration in the nitrogen atmosphere of 300 to 500 ppm. However, although nitrogen gas with an oxygen concentration of 5 ppm or less was circulated in the crystallization process, the dew point washed with a scrubber was 0 ° C or less and only 0.5% fresh nitrogen gas was replenished in the solid phase polymerization process. Nitrogen gas having an oxygen concentration of 200 to 400 ppm was supplied. The results are shown in Table 4.

(Comparative Example 8)
In all steps from storage of terephthalic acid to the end of the melt polycondensation step, PET was obtained by reacting in the same manner as in Example 1 except that the following conditions were adopted, and evaluation was performed in the same manner as in Example 1.
1) Gas phase portion of terephthalic acid storage silo, terephthalic acid slurry blending tank and storage tank 2) Air atmosphere 2) Do not allow inert gas to flow through ethylene glycol 3) Do not allow inert gas to flow through catalyst or phosphorus compound solution In addition, inert gas does not flow through the gas phase portion. 4) No inert gas is passed through the gas phase portion of the esterification reaction apparatus. 5) The reaction temperature of the final reactor during the polycondensation reaction is about 301.degree. Table 5 shows the maintenance results.

(Comparative Example 9)
PET was obtained by reacting in the same manner as in Example 1 except that the wavelength of the near-infrared lamp of the preliminary crystallization apparatus, crystallization apparatus and solid phase polymerization apparatus of Example 1 was changed as shown in Table 5. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 5.

(Comparative Example 10)
The reaction was carried out in the same manner as in Example 1 except that the wavelength of the near-infrared lamp of the preliminary crystallization apparatus, the crystallization apparatus and the solid phase polymerization apparatus of Example 1 and the oxygen concentration in the nitrogen gas atmosphere were changed as shown in Table 5. PET was obtained and evaluated in the same manner as in Example 1. The results are shown in Table 5.

(Comparative Example 11)
PET was obtained by reacting in the same manner as in Example 1 except that the wavelength of the near-infrared lamp of the pre-crystallization apparatus of Example 1 and the oxygen concentration in the nitrogen gas atmosphere were changed as shown in Table 5. Example 1 It was evaluated in the same manner as above. The results are shown in Table 5.

(Comparative Example 12)
PET was obtained by reacting in the same manner as in Example 1 except that the wavelength of the near-infrared lamp and the oxygen concentration in the nitrogen gas atmosphere of Example 1 were changed as shown in Table 5. Evaluation was performed in the same manner as in Example 1. The results are shown in Table 5.

In addition, 1) -8) of conditions [1] described in footnotes of Tables 1-5 are as follows.
1) An inert gas having an oxygen concentration of 5 ppm or less is circulated in the gas phase portion of the terephthalic acid slurry preparation tank and storage tank.
2) Maintain the oxygen concentration in the gas phase part of the terephthalic acid slurry preparation tank and storage tank at 100 ppm or less.
3) Pass an inert gas having an oxygen concentration of 5 ppm or less through ethylene glycol.
4) An inert gas having an oxygen concentration of 5 ppm or less is passed through the catalyst or phosphorus compound solution, and the inert gas is circulated in the gas phase portion.
5) An inert gas having an oxygen concentration of 5 ppm or less is passed through the gas phase portion of the esterification reactor.
6) The reaction temperature of the final reactor during the polycondensation reaction is maintained at 265 to 300 ° C.
7) Water that satisfies all of the following (1) to (5) is used as cooling water during chip formation.
Na ≦ 1.0 (ppm) (1)
Mg ≦ 1.0 (ppm) (2)
Si ≦ 2.0 (ppm) (3)
Ca ≦ 1.0 (ppm) (4)
COD ≤ 2.0 (mg / l) (5)
8) Maintain the atmosphere in the terephthalic acid storage silo in an inert gas atmosphere with an oxygen concentration of 200 ppm or less.

  The aromatic polyester of the present invention is excellent in transparency, heat resistance, mechanical properties and aroma retention, and is useful as a container or packaging material for food or beverages.

(1): Raw material chip supply port (2): Overflow discharge port (3): Discharge port for polyester chip and treated water (4): Draining device (5): Fine removal device (6): Pipe (7): Recycled water and / or ion exchange water inlet (8): Adsorption tower (9): Ion exchange water inlet

Claims (8)

  An aromatic polyester having a repeating unit consisting of an aromatic dicarboxylic acid component and a glycol component, and obtained by subjecting a molded article made of the aromatic polyester to extraction treatment at 80 ° C. for 1 hour in ultrapure water. When the bitterness value and astringency value are measured with a taste inspection apparatus equipped with a taste sensor composed of an artificial lipid membrane, the difference between the extracted water bitterness value and the ultrapure water bitterness value and the astringent taste of the extracted water A difference between the value and the astringency value of ultrapure water is 0.5 or less, respectively.   2. The aromatic polyester according to claim 1, wherein the acetaldehyde content is 10 ppm or less.   2. The aromatic polyester according to claim 1, wherein the content of the cyclic ester oligomer is 0.70% by weight or less.   The aromatic polyester according to any one of claims 1 to 3, wherein an increase amount of the cyclic ester oligomer when melted at a temperature of 290 ° C for 60 minutes is 0.40% by weight or less.   The aromatic polyester according to any one of claims 1 to 4, wherein the aromatic polyester is formed into chips after polycondensation and is contact-treated with water at 20 to 120 ° C.   A polyester molded article obtained by melt-molding the aromatic polyester according to any one of claims 1 to 5.   The polyester molding according to claim 6, wherein the polyester molding is a hollow molding, a sheet-like material, or a stretched film and a nonwoven fabric obtained by stretching the sheet-like material in at least one direction. body.   The polyester molded body according to claim 6, wherein the polyester molded body is a coating obtained by melt-extruding the aromatic polyester on a base material.

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