JP2003176347A - Polyester, hollow moldings, sheets and oriented film therefrom - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester which reduces the scale smearing in the tank and piping for water treatment of polyester chips and shows excellent transparency, heat resistance, mechanical properties and good smell-retaining properties with retention of strange taste and smell reduced, when the chips are molded. <P>SOLUTION: The polyester that is treated with water in the chip form after polycondensation polymerization mainly contains aromatic dicarboxylic acid as an acid component and has a free glycol content of ≤30 ppm originating from the polyester, a free aromatic dicarboxylic monoglycol ester content of ≤50 ppm, a free aromatic dicarboxylic diglycol ester content of ≤70 ppm, a content of free dimer from aromatic dicarboxylic acid and glycol of ≤200 ppm and a fines content of 0.1-500 ppm. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyester preferably used as a raw material for molded products such as hollow molded products such as beverage bottles, sheet-shaped products, stretched films and the like, and a molded product comprising the same. In particular, it relates to a small hollow molded article that is unlikely to cause residual offensive odor or offensive odor in a molded article and is excellent in transparency and heat-resistant dimensional stability, and a sheet-like material and a stretched film that are excellent in transparency, slipperiness, and dimensional stability after molding. It is a thing. Further, the present invention relates to a polyester having good mold releasability from a heat treatment mold when molding a small hollow molded article and excellent in long-term continuous moldability.

[0002]

Polyesters represented by polyethylene terephthalate, polyethylene-2,6-naphthalate, etc. have high mechanical value and high chemical value, and thus have high industrial value, and can be used for fibers, films, sheets and bottles. It is widely used as a polymer to form

As a material for containers such as seasonings, oils, beverages, cosmetics and detergents, various resins have been adopted depending on the type of filling contents and the purpose of use.

Among these resins, polyester is excellent in mechanical strength, heat resistance, transparency and gas barrier property, and is therefore most suitable as a material for a beverage filling container such as juice, soft drink and carbonated drink. . Such polyester is supplied to a molding machine such as an injection molding machine to mold a preform for a hollow molded body, and the preform is inserted into a mold of a predetermined shape and stretch blow molded, and then the body of the bottle is heat treated ( It is general to heat-set) to form a hollow molded body, and further heat-treat the mouth part of the bottle (crystallize the mouth part) if necessary.

However, conventional polyesters contain a considerable amount of cyclic trimers and other oligomers, and these oligomers adhere to the inner surface of the mold, the gas exhaust port of the mold, and the exhaust pipe. Mold stains were likely to occur.

Further, the polyester contains acetaldehyde which is a by-product. When the content of acetaldehyde in the polyester is high, the content of acetaldehyde in the containers and other packaging materials molded from this is also high, which affects the flavor and odor of the beverage filled in these containers. Therefore, conventionally, various measures have been taken to reduce the acetaldehyde content in polyester. Furthermore, when used as a container for low-flavored beverages such as mineral water and oolong tea, generally, when these beverages are heat-filled or sterilized by heating after filling, the acetaldehyde content of the beverage container is reduced. It has been found that the flavor and odor of these contents cannot be improved merely by keeping them.

[0007] For beverage metal cans, for the purpose of process simplification, hygiene, and pollution prevention, a metal plate coated with a polyester film having ethylene terephthalate as a main repeating unit on its inner surface is used for can making. The method of doing has come to be adopted. Also in this case, it has been found that when the contents are filled and sterilized by heating at a high temperature, even if a film having a low acetaldehyde content is used, the flavor and odor of the contents cannot be improved.

[0008]

Various proposals have been made to solve such problems. For example, Japanese Patent Application Laid-Open No. 4-21124 proposes polyethylene terephthalate, which is obtained by water treatment and has a small increase in acetaldehyde during molding. However, when the water treatment equipment is operated for a long time, the treatment tank, piping, and the like become heavily soiled, and there arises a problem that a residual taste or smell is generated in the obtained polyester molded product.

The present invention solves the problems of the prior art, reduces the contamination of the treatment tank and piping during the water treatment of polyester chips, and is transparent, heat-resistant, and It is an object of the present invention to provide a polyester which has little mechanical properties, residual off-taste, and off-flavor and is excellent in aroma retention.

[0010]

In order to achieve the above object, the polyester of the present invention is a polyester which is water-treated in the form of chips after polycondensation, and the acid component of the polyester is mainly an aromatic dicarboxylic acid, The content of free glycol derived from the polyester is 30 ppm or less,
Free aromatic dicarboxylic acid monoglycol ester content is 50 ppm or less, free aromatic dicarboxylic acid diglycol ester content is 70 ppm or less, and free dimer content of aromatic dicarboxylic acid and glycol is 2 or less.
00ppm or less, fine content 0.1-500pp
It is characterized by being m.

The polyester having the above-mentioned constitution is less likely to cause mold stains when molding a molded product, is less likely to cause residual off taste and odor in the molded product, and has excellent transparency and heat-resistant dimensional stability. In addition, it is possible to obtain a sheet-like material or a stretched film having excellent transparency, heat resistance, mechanical properties and aroma retention.

In this case, the fine content is 150 pp
It can be m or less, further 25 ppm or less.

In this case, the main aromatic dicarboxylic acid is terephthalic acid, and the main glycol is ethylene glycol, or the main aromatic dicarboxylic acid is 2,6-naphthalenedicarboxylic acid. Can be a polyester where is ethylene glycol.

Further, in this case, the acid component of the polyester is mainly terephthalic acid, the glycol component is mainly ethylene glycol, and the intrinsic viscosity is 0.68 to
0.90 deciliter / g, density 1.37 g / cm ³
As described above, the content of free ethylene glycol is 15 ppm or less, the content of free diethylene glycol is 5 ppm or less, the content of free monohydroxyethyl terephthalate is 40 ppm or less, the content of free bishydroxyethyl terephthalate is 50 ppm or less, and the free bishydroxyethyl. The terephthalate dimer content can be 100 ppm or less.

Further, in this case, the polyester is formed into a chip shape after polycondensation, and the content of the glycol derived from the polyester, the content of the aromatic dicarboxylic acid monoglycol ester and the aromatic dicarboxylic acid are formed in the treatment tank. The content of diglycol ester is 100pp each
It can be treated with less than m of treated water.

Further, in this case, the polyester may be formed into chips after polycondensation and treated with treated water satisfying the following conditions (a) and (b) in a treatment tank. (A) Temperature 40 to 120 ° C. (b) Treated water including wastewater from the treatment tank

Further, in this case, the polyester may be formed into chips after polycondensation and treated with treated water satisfying the condition (c) below in a treatment tank. (C) Treated water having a polyester fine powder content of 1000 ppm or less

Further, in this case, the hollow molded article may be formed by molding the polyester.

Further, in this case, the sheet-like material may be formed by molding the polyester.

Furthermore, in this case, the stretched film is
The sheet material may be stretched in at least one direction.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester of the present invention is preferably a crystalline polyester mainly obtained from an aromatic dicarboxylic acid component and a glycol component, more preferably 85 mol of the aromatic dicarboxylic acid unit of the acid component. % Polyester, and particularly preferably, the polyester in which the aromatic dicarboxylic acid unit contains 90 mol% or more of the acid component.

The aromatic dicarboxylic acid component constituting the polyester of the present invention includes terephthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, diphenoxyethanedicarboxylic acid and other aromatic dicarboxylic acids. And functional derivatives thereof and the like.

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

The polyester can be used by being copolymerized. Acid components include terephthalic acid and 2,6
-Aromatic dicarboxylic acids such as naphthalenedicarboxylic acid, isophthalic acid, diphenyl-4,4'-dicarboxylic acid, diphenoxyethanedicarboxylic acid, oxyacids such as p-oxybenzoic acid, oxycaproic acid and their functional derivatives, adipine Acids, sebacic acid, succinic acid, glutaric acid, dimer acid and other aliphatic dicarboxylic acids and their functional derivatives, hexahydroterephthalic acid, hexahydroisophthalic acid, cyclohexanedicarboxylic acid and other alicyclic dicarboxylic acids and their functional derivatives And so on.

As the glycol component used by copolymerization in the polyester, aliphatic glycols such as ethylene glycol, trimethylene glycol, tetramethylene glycol, diethylene glycol and neopentyl glycol, bisphenol A, and alkylene oxide addition of bisphenol A are added. Aromatic glycol such as things,
Examples thereof include polyalkylene glycols such as polyethylene glycol and polybutylene glycol.

Further, polyfunctional compounds such as trimellitic acid, trimesic acid, pyromellitic acid, tricarballylic acid, glycerin, pentaerythritol and trimethylolpropane are copolymerized within the range where the polyester is substantially linear. Alternatively, a monofunctional compound such as benzoic acid or naphthoic acid may be copolymerized.

A preferred example of the polyester of the present invention is
The main repeating unit is a polyester composed of ethylene terephthalate, more preferably a linear polyester containing 85 mol% or more ethylene terephthalate units, and particularly preferably a linear polyester containing 95 mol% or more ethylene terephthalate units, that is,
Polyethylene terephthalate (hereinafter sometimes abbreviated as PET).

Another preferred example of the polyester of the present invention is a polyester whose main repeating unit is ethylene-2,6-naphthalate, and more preferably 85 ethylene-2,6-naphthalate units.
A linear polyester containing mol% or more, particularly preferably a linear polyester containing 90 mol% or more of ethylene-2,6-naphthalate units, that is, a polyethylene naphthalate homopolymer or a polyethylene naphthalate copolymer containing ethylene terephthalate units. (Hereinafter, it may be abbreviated as PEN).

The intrinsic viscosity of the polyester of the present invention, especially the polyester whose main repeating unit is ethylene terephthalate, is 0.50 to 1.30 deciliter / g, preferably 0.55 to 1.20 deciliter / g.
g, more preferably 0.60 to 0.90 deciliter / g. Intrinsic viscosity is 0.50 deciliters /
If it is less than g, the mechanical properties of the obtained molded article and the like are poor.
On the other hand, when it exceeds 1.30 deciliter / g, the resin temperature becomes high during melting by a molding machine and the thermal decomposition becomes severe, and free low molecular weight compounds that affect the aroma retention are increased or the molded product is increased. Will be colored yellow.

The intrinsic viscosity of the polyester of the present invention, particularly the polyester whose main repeating unit is ethylene-2,6-naphthalate, is 0.40 to 1.
00 deciliter / g, preferably 0.42 to 0.95
Deciliter / g, more preferably 0.45 to 0.9
It is in the range of 0 deciliter / g. Intrinsic viscosity 0.40
When it is less than deciliter / g, the mechanical properties of the obtained molded product are poor. On the other hand, if it exceeds 1.00 deciliter / g, the resin temperature becomes high when melted by a molding machine or the like, and thermal decomposition becomes violent, resulting in an increase in free low-molecular-weight compounds that affect aroma retention, or a molded product. Will be colored yellow.

The shape of the polyester chip may be any of cylinder type, square type, flat plate type and the like, and the size thereof is usually 1.5 to 4 mm in length, width and height.
Is the range. For example, in the case of a cylinder type, it is practical that the length is 1.5 to 4 mm and the diameter is about 1.5 to 4 mm. Further, it is practical that the weight of the chip is in the range of 15 to 30 mg / piece.

The flavor of the content such as a beverage which is in direct contact with the molded article made of polyester, the content of the free low molecular weight compound remaining in the polyester material, and the amount of these compounds eluted into the content As a result of intensive studies on the relationship, as a result, not only specific low-molecular weight compounds but also various free low-molecular weight compounds such as glycols listed below were eluted in the contents, but they were complexed. It was found that the flavor of the contents was affected.

According to the present invention, the upper limit of the free low molecular weight compound is, in a polyester mainly composed of an aromatic dicarboxylic acid, a free glycol content derived from the polyester of 30 ppm or less, a free aromatic dicarboxylic acid monoglycol. Ester content is 50ppm or less, free aromatic dicarboxylic acid diglycol ester content is 7
The content of the free dimer composed of 0 ppm or less and the aromatic dicarboxylic acid and glycol is 200 ppm or less.

The free glycol content is preferably 2
0 ppm or less, more preferably 10 ppm or less, the free aromatic dicarboxylic acid monoglycol ester content is preferably 30 ppm or less, more preferably 10 ppm or less, and the free aromatic dicarboxylic acid diglycol ester content is preferably 50ppm or less,
It is more preferably 30 ppm or less, and the content of the free dimer consisting of aromatic dicarboxylic acid and glycol is preferably 100 ppm or less, more preferably 7 ppm.
It is 5 ppm or less. The polyester has a free glycol content of more than 30 ppm, a free aromatic dicarboxylic acid monoglycol ester content of more than 50 ppm, a free aromatic dicarboxylic acid diglycol ester content of more than 70 ppm, and an aromatic dicarboxylic acid. Content of free dimer consisting of acid and glycol is 200pp
When it exceeds m, the flavor and aroma of the contents in the container obtained from the polyester are extremely deteriorated. As described above, these free low-molecular-weight compounds are eluted into the contents, although the amount is very small, from the material of the container made of polyester, and as a result, the flavor and the like of the contents are affected.

Here, when the polyester is PET,
The glycol is ethylene glycol and diethylene glycol, the monomer consisting of an aromatic dicarboxylic acid and glycol is monohydroxyethyl terephthalate and bishydroxyethyl terephthalate, and the dimer consisting of an aromatic dicarboxylic acid and glycol. Is a dimer of bishydroxyethyl terephthalate.

When the polyester is PEN, the glycol is ethylene glycol and diethylene glycol, and the monomer composed of aromatic dicarboxylic acid and glycol is 2,6-monohydroxyethyl naphthalate and 2,6- It is bishydroxyethyl naphthalate, and the dimer composed of aromatic dicarboxylic acid and glycol is a dimer of 2,6-bishydroxyethyl naphthalate.

Further, the preferred polyesters of the present invention
Is terephthalic acid as the main aromatic dicarboxylic acid.
The main glycol is ethylene glycol
Ester with an intrinsic viscosity of 0.68-0.90 deci
Liter / g, preferably 0.69-0.88 deciliters
Torr / g, more preferably 0.70 to 0.86 deci
Tttle / g and density is 1.37 g / cm^ThreeAbove, good
More preferably 1.38 g / cm ^ThreeAbove, more preferably
1.39 g / cm^ThreeAnd above, free ethylene glycol
Content of 15 ppm or less, preferably 10 ppm or less
Below, more preferably below 5 ppm, free diethyl
Glycol content is 5ppm or less, preferably 4pp
m or less, more preferably 3 ppm or less
Monohydroxyethyl terephthalate content is 40pp
m or less, preferably 30 ppm or less, more preferably
Free bishydroxyethyl te
Lephthalate content is 50 ppm or less, preferably 40
ppm or less, more preferably 30 ppm or less, and play
Content of bishydroxyethyl terephthalate dimer
Is 100 ppm or less, preferably 75 ppm or less,
Is preferably 60 ppm or less, and is in the form of chips after polycondensation
It is a polyester characterized by being treated with water. This
When polyester such as is used for food packaging materials,
The alteration of the flavor of the contents is greatly improved.

The free glycol content in the polyester alone is maintained at 30 ppm or less, or the free aromatic dicarboxylic acid monoglycol ester content and the free aromatic dicarboxylic acid diglycol ester content are only 50 ppm or less, respectively. The flavor and aroma of the contents in the container obtained from the polyester are not improved only by maintaining the content at 70 ppm or less. In order to obtain a hollow molded article, a sheet-like material or a stretched film having little residual off-taste and off-flavor and having an excellent aroma-preserving property, and a container or a packaging material from them, a free glycol content, a free aromatic dicarboxylic acid monoglycol Water treatment in the form of chips in which the content of ester, the content of free aromatic dicarboxylic acid diglycol ester, and the content of free dimer consisting of aromatic dicarboxylic acid and glycol are suppressed within the above ranges, respectively. It is necessary to use the above polyester.

The acetaldehyde content of the polyester of the present invention is 8 ppm or less, preferably 6 ppm or less, more preferably 4 ppm or less, and the formaldehyde content is 6 ppm or less, preferably 5 ppm or less, more preferably 4 ppm or less. Acetaldehyde content of 8ppm or more, and formaldehyde content of 6
If it is more than ppm, the flavor and odor of the contents such as a container molded from this polyester are deteriorated.

The amount of diethylene glycol copolymerized in the polyester of the present invention is 1.0 to 5.0 mol%, preferably 1.3 to 4.5 mol%, more preferably 1.3 to 4.5 mol% of the glycol component constituting the polyester. Is 1.5-4.
It is 0 mol%. When the amount of diethylene glycol exceeds 5.0 mol%, the thermal stability is deteriorated, the molecular weight is greatly reduced during molding, and the acetaldehyde content and the formaldehyde content are greatly increased, which is not preferable. Further, when the amount of diethylene glycol is less than 1.0 mol%, the transparency of the obtained molded product deteriorates.

The content of the cyclic trimer in the polyester of the present invention is 0.50% by weight or less, preferably 0.45.
It is less than or equal to wt%, more preferably less than or equal to 0.40 wt%. When a heat-resistant hollow molded article or the like is molded from the polyester of the present invention, heat treatment is carried out in a heating mold, and
When the content of the monomer is 0.50% by weight or more,
The oligomer adhesion to the surface of the heating die rapidly increases, and the transparency of the obtained hollow molded article is extremely deteriorated.

The above-mentioned polyester of the present invention can be produced, for example, as follows. That is, the polyester of the present invention is obtained by subjecting the following polyester chips to contact treatment with water having a specific concentration in which the glycol content derived from the polyester and the minor component content such as aromatic dicarboxylic acid monoglycol ester are shown below. Can be manufactured by. Examples of the contact treatment method include a method of immersing in water. The time for carrying out the contact treatment with water is 5 minutes to 2 days, preferably 10 minutes to 1 day,
It is more preferably 30 minutes to 10 hours, and the temperature of water is 20 to 180 ° C, preferably 40 to 150 ° C, and more preferably 50 to 120 ° C.

The polyester chips are aldehyde compounds such as acetaldehyde and formaldehyde produced as a by-product during the production of polyester, aromatic dicarboxylic acids and glycols which are raw materials, monomers and aromatic compounds which are aromatic dicarboxylic acids and glycols which are reaction products. It contains low molecular weight compounds such as dimers consisting of dicarboxylic acids and glycols, and these aldehyde compounds, aromatic dicarboxylic acids, glycols, monomers and dimers consisting of aromatic dicarboxylic acids and glycols in treated water are treated during water treatment. Elute.

Regardless of whether the polyester chips are treated with water continuously or batchwise, if all or most of the treated water discharged from the treatment tank is made to flow as industrial wastewater, a large amount of new treated water will be produced. Not only is it needed, but there is concern that the increase in industrial wastewater will affect the environment. In other words, by returning at least a portion of the treated water discharged from the treatment tank to the water treatment tank and reusing it, it is possible to reduce the required amount of treated water and reduce the impact on the environment due to an increase in the amount of wastewater. Moreover, if the temperature of the waste water returned to the water treatment tank maintains a certain level, the heating amount of the treated water can be reduced.

From the economical point of view and the environmental point of view, in the case of batch type water treatment, the treated water is repeatedly used, and
In the case of continuous water treatment, the treated water discharged from the water treatment tank is returned to the treatment tank for reuse, and in any case, acetaldehyde content, glycol content, aromatic dicarboxylic acid and glycol in the treatment tank are reused. The monomer content and the dimer content consisting of the When the amount of these compounds is large, the content of these compounds in the chips after water treatment and drying becomes high, and the flavor and aroma of the contents in hollow molded articles using such polyester chips become very bad. . Further, the treatment tank of the water treatment device and the piping become heavily soiled.

Specifically, in the case of the continuous water treatment method, the polyester of the present invention contains a glycol content derived from the polyester in the treated water discharged from the treatment tank together with the polyester chips, an aromatic dicarboxylic acid monoglycol ester content, Aromatic dicarboxylic acid diglycol ester content and consisting of aromatic dicarboxylic acid and glycol 2
It is obtained by treating polyester chips while maintaining the content of each monomer below 100 ppm. In the case of a batch system, the glycol content derived from the polyester in the treated water in the treatment tank at the end of the water treatment, the aromatic dicarboxylic acid monoglycol ester content, the aromatic dicarboxylic acid diglycol ester content and the aromatic content 10 dimers each consisting of dicarboxylic acid and glycol
It can also be obtained by treating the polyester chips while maintaining the concentration below 0 ppm.

The method of industrially performing water treatment is illustrated below, but the method is not limited to this. Further, the treatment method may be either continuous type or batch type,
The continuous method is preferred for industrial use.

When the polyester chips are subjected to a batch type water treatment, a silo type treatment tank may be used. That is, the polyester chips are received in a silo in a batch method and treated with water. Alternatively, it is also possible to receive the polyester chips in a rotary tube type treatment tank and perform water treatment while rotating them to make the contact with water more efficient.

In this case, the polyester chips are charged and filled in the treatment tank and filled with the treatment water, and the treatment water circulates continuously or intermittently (may be collectively referred to as continuous) as necessary, and Part of the treated water will be discharged continuously or intermittently and new treated water will be additionally supplied. And P
In the case of ET, the total content of ethylene glycol content and diethylene glycol content in the water at the end of the water treatment, bishydroxyethyl terephthalate content, monohydroxyethyl terephthalate content and bishydroxyethyl terephthalate dimer The PET of the present invention is obtained by treating the PET chips having the above characteristics while maintaining the contents at 100 ppm or less, preferably 50 ppm or less, more preferably 30 ppm or less.

When the polyester chips are continuously treated with water, the polyester chips are continuously or intermittently received from the upper part in a tower-type treatment tank, and water is continuously supplied in a cocurrent or countercurrent to treat the water. Can be made.

However, when the concentration of glycol or the like in the treated water increases rapidly due to production conditions such as polycondensation of polyester and water treatment, the treated chips from the treated tank are not returned to the treated tank. You can also do it.

In the case of PET, in the present invention, the total content of the ethylene glycol content and the diethylene glycol content in the treated water continuously supplied to the water treatment tank, the bishydroxyethyl terephthalate content, and the monohydroxyethyl terephthalate content. And the content of the bishydroxyethyl terephthalate dimer is 100 ppm or less, preferably 50 ppm or less, more preferably 30 ppm or less.
The polyester of the present invention is obtained by adjusting the content to be ppm or less.

A method of making the content of glycol or the like in the treated water continuously supplied to the water treatment tank 100 ppm or less will be illustrated below, but the present invention is not limited to this.

Further, by using the following method, not only glycol in the treated water but also trace amounts of odorous components such as acetaldehyde, formaldehyde, acetic acid, formic acid can be removed,
The content of these in the treated water can be kept below a certain value.

In order to suppress an increase in the content of glycol or the monomer composed of aromatic dicarboxylic acid and glycol in the treated water continuously supplied to the water treatment tank, the treated water is discharged from the water treatment tank and the water is again treated. An apparatus for removing glycol and the like is installed at at least one place during the process until the circulating water is returned to the treatment tank.

As a method for removing glycol and the like,
Known methods such as a distillation treatment with a distillation apparatus, an activated carbon adsorption treatment, a bubbling treatment of an inert gas into water, and a heat degassing treatment can be mentioned. Another method is to add new ion-exchanged water to the circulating water.

In order to obtain a molded product having excellent heat-resistant dimensional stability and a sheet-like product having excellent dimensional stability after molding,
Fine content of water-treated polyester 0.1-5
It is necessary to set it to 00 ppm. If the fine content is less than 0.1 ppm, the crystallization rate will be very slow and the mouthpiece of the hollow molded article will be insufficiently crystallized. Therefore, the shrinkage of the mouthpiece will fall within the specified range. Since it does not subside, a capping phenomenon occurs, and a sheet-like material having poor dimensional stability after molding the container is provided. Also, 50
If it exceeds 0 ppm, the crystallization speed will be high and the crystallization of the plug part of the hollow molded article will be excessive, and the shrinkage amount of the plug part will not fall within the specified range, resulting in poor capping of the plug part. May leak contents, or
The preform for blow molding is whitened, which makes normal stretching impossible.

Here, granules or powders, which are considerably smaller than chips generated in the polyester manufacturing process including a water treatment process, are called fine. The fine copolymerization component and the content of the copolymerization component are the same as those of the polyester chips, and the intrinsic viscosity thereof is usually the same as that of the chips, or 0.03 from the intrinsic viscosity of the chips.
(Deciliter / g) A range of high intrinsic viscosity is preferable.

The fine content is 0.1 to 500 p
The pm polyester can be easily produced by controlling the amount of fine powder in the treated water. When water with a fine powder amount of 0 ppm is used as treated water, the fine content of polyester may be less than 0.1 ppm, and when water with a fine powder amount of more than 1000 ppm is used, the fine amount in the polyester may exceed 500 ppm. There is. Here, the fine in the water treatment tank is referred to as fine powder, and its content in the treated water, that is, the amount of fine powder can be measured by the following measuring method. The particle size is usually about 30 to 1300 μm.

The treated water discharged from the water treatment tank contains fines already attached to the polyester chips when the polyester chips are received in the treatment tank, and friction between the polyester chips or the walls of the treatment tank during the water treatment. Contains polyester fines generated in. Therefore, when the treated water discharged from the treatment tank is returned to the treatment tank and reused, the amount of fine powder contained in the treated water in the treatment tank gradually increases. Therefore, the fine powder contained in the treated water may adhere to the treatment tank wall or the pipe wall to clog the pipe. Also, the fine powder contained in the treated water adheres to the polyester chips again, and after this, fine particles adhere to the polyester chips due to the electrostatic effect at the stage of drying and removing water, so perform fine removal after drying. Also becomes difficult to remove.

The water-treated polyester chips are drained by a draining device such as a vibrating screener or Simon Carter, and transferred to a drying step. As a matter of course, the water separated from the polyester chips by the drainer is a filter type filtration device,
It is sent to a fine removal device such as a centrifuge and can be used again for water treatment.

In the case where the contents put in the container are mineral water whose flavor and odor are very strictly controlled, water-treated polyester chips are washed with new ion-exchanged water to clean the chip surface. It is also possible to wash off the attached low molecular weight compound consisting of aromatic dicarboxylic acid and glycol, and transfer it to the drying step. The ion-exchanged water after washing is returned to the water treatment tank and used again.

For drying the polyester chips, a commonly used polyester chip drying treatment can be used. As a continuous drying method, a hopper-type aeration dryer in which polyester chips are supplied from the upper part and a dry gas is aerated from the lower part is usually used. As a method for reducing the amount of dry gas and efficiently drying, a rotating disk type continuous dryer is selected, and while supplying a small amount of dry gas, heating steam, heating medium, etc. are supplied to the rotating disk and the outer jacket. The formed granular polyester chips can be dried indirectly.

A double-cone type rotary dryer is used as a dryer for batch-type drying, and can be dried under vacuum or under vacuum while a small amount of dry gas is passed through. Alternatively, it may be dried under atmospheric pressure while aerating a dry gas.

Although atmospheric air may be used as the dry gas, dry nitrogen and dehumidified air are preferable from the viewpoint of preventing a decrease in the molecular weight due to hydrolysis or thermal oxidative decomposition of the polyester.

The polyester used for the water treatment can be manufactured by a conventionally known manufacturing method. That is, in the case of PET, a direct esterification method in which terephthalic acid, ethylene glycol and optionally other copolymerization components are directly reacted to distill off water to esterify, and then polycondensate under reduced pressure, or It is produced by a transesterification method in which dimethyl terephthalate is reacted with ethylene glycol and, if necessary, other copolymerization components to distill off methyl alcohol for transesterification, and then polycondensation is performed under reduced pressure. Further, solid phase polymerization may be performed to increase the intrinsic viscosity and reduce the acetaldehyde content and the like.

The melt polycondensation reaction may be carried out in a batch reactor or a continuous reactor. In any of these methods, the melt polycondensation reaction may be carried out in one step or may be carried out in multiple steps. The solid phase polymerization reaction can be carried out by a batch type apparatus or a continuous type apparatus as in the melt polycondensation reaction. The melt polycondensation and the solid phase polymerization may be performed continuously or may be performed separately.

In the case of the direct esterification method, compounds such as Ge, Ti and Sb are used as the polycondensation catalyst, and it is particularly preferable to use the Ge compound and / or the Ti compound.

As the Ge compound, amorphous germanium dioxide, crystalline germanium dioxide powder or a slurry of ethylene glycol, a solution of crystalline germanium dioxide dissolved in water by heating, a solution of ethylene glycol added thereto and heat treatment, or the like is used. However, in particular, in order to obtain the polyester used in the present invention, it is preferable to use a solution in which germanium dioxide is heated and dissolved in water, or a solution in which ethylene glycol is added and heated. These polycondensation catalysts can be added during the esterification process. G
When the e compound is used, its amount is 20 to 150 ppm, preferably 2 as the Ge residual amount in the polyester.
3 to 100 ppm, more preferably 25 to 70 ppm
Is.

Examples of the Ti compound include tetraethyl titanate, tetraisopropyl titanate, tetra-n-propyl titanate, tetra-n-butyl titanate, and other tetraalkyl titanates and their partial hydrolysates, titanyl oxalate, titanyl ammonium oxalate, and titanyl oxalate. Sodium, potassium titanyl oxalate, calcium titanyl oxalate, titanyl oxalate compounds such as strontium titanyl oxalate, titanium trimellitate, titanium sulfate,
Examples include titanium chloride. The Ti compound is added so that the amount of Ti remaining in the produced polymer is in the range of 0.1 to 10 ppm.

As the stabilizer, it is preferable to use phosphoric acid, polyphosphoric acid, phosphoric acid esters such as trimethyl phosphate, or 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 amount of P remaining in the produced polymer is in the range of 5 to 100 ppm.

DE copolymerized in polyester
In order to control the G content, a basic compound, for example, a tertiary amine such as triethylamine or tri-n-butylamine, a quaternary ammonium salt such as tetraethylammonium hydroxide, or the like can be added to the esterification step.

Further, the polyester to be subjected to the water treatment is a polyester composed of an aromatic dicarboxylic acid, and the free glycol content derived from the polyester is 50 ppm or less and the free aromatic dicarboxylic acid monoglycol ester is contained. 70ppm or less, free aromatic dicarboxylic acid diglycol ester content 100pp
A polyester having a content of m or less and a content of a free dimer consisting of an aromatic dicarboxylic acid and a glycol is 350 ppm or less is preferable.

As the polyester to be subjected to water treatment, a polyester whose main aromatic dicarboxylic acid is terephthalic acid and whose main glycol is ethylene glycol has an intrinsic viscosity of 0.68 to 0.90 deciliter / g, density is 1.37 g / cm ³ or more, free ethylene glycol content is 20 ppm or less, free diethylene glycol content is 10 ppm or less, free monohydroxyethyl terephthalate content is 50 ppm or less, free bishydroxy Ethyl terephthalate content is 70 ppm or less, and free bishydroxyethyl terephthalate dimer content is 350 p
It is preferable that the polyester is pm or less.

Further, the acetaldehyde content of the polyester used for the water treatment is 10 ppm or less, the formaldehyde content is 8 ppm or less, and the amount of diethylene glycol copolymerized with the polyester is 1.0 to 5% of the glycol component constituting the polyester. The content of 0 mol% and cyclic trimer is preferably 0.50% by weight or less.

Saturated fatty acid monoamide, unsaturated fatty acid monoamide, saturated fatty acid bisamide, unsaturated fatty acid bisamide and the like can be used in combination with the polyester of the present invention at the same time.

Examples of the saturated fatty acid monoamide include lauric acid amide, palmitic acid amide, stearic acid amide and behenic acid amide. Examples of unsaturated fatty acid monoamides include oleic acid amide, erucic acid amide, ricinoleic acid amide, and the like. Examples of the saturated fatty acid bisamide include methylenebisstearic acid amide, ethylenebiscapric acid amide, ethylenebislauric acid amide, ethylenebisstearic acid amide,
Examples thereof include ethylenebisbehenic acid amide, hexamethylenebisstearic acid amide, and hexamethylenebisbehenic acid amide. Examples of unsaturated fatty acid bisamides include ethylenebisoleic acid amide and hexamethylenebisoleic acid amide. Preferred amide compounds are saturated fatty acid bisamide, unsaturated fatty acid bisamide and the like. The compounding amount of such an amide compound is in the range of 10 ppb to 1 × 10 ⁵ ppm.

Further, a metal salt compound of an aliphatic monocarboxylic acid having 8 to 33 carbon atoms, such as naphthenic acid, caprylic acid,
Lithium salts, sodium salts, potassium salts, magnesium salts, calcium salts of saturated and unsaturated fatty acids such as capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, behenic acid, montanic acid, melissic acid, oleic acid, and linoleic acid. It is also possible to use a salt, a cobalt salt and the like together. The compounding amount of these compounds is in the range of 10 ppb to 300 ppm.

The polyester of the present invention can be preferably used as a hollow molded article, a tray, a packaging material such as a biaxially stretched film, a film for coating a metal can and the like. Also,
The polyester of the present invention can also be used as one constituent layer such as a multilayer molded body or a multilayer film.

The polyester of the present invention may be mixed with various additives such as known ultraviolet absorbers, lubricants, release agents, nucleating agents, stabilizers, antistatic agents, pigments and the like, if necessary.
In addition, the measuring method of the main characteristic value in this invention is demonstrated below.

[0081]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples. In addition, the measuring method of the main characteristic value in this specification is demonstrated below.

(1) Intrinsic viscosity (IV) of polyester It was determined from the solution viscosity at 30 ° C. in a 1,1,2,2-tetrachloroethane / phenol (2: 3 weight ratio) mixed solvent.

(2) Diethylene glycol content of polyester (DEG content) Degradation with methanol and quantification of the DEG amount by gas chromatography were carried out and expressed as a ratio (mol%) to all glycol components.

(3) Density Carbon tetrachloride / n-heptane mixed solvent 25 with a density gradient tube
It was measured at ° C.

(4) Content of cyclic trimer of polyester (CT content) 300 mg of a sample was dissolved in 3 cc of hexafluoroisopropanol / chloroform mixture (volume ratio = 2/3), and 30 cc of chloroform was added to dilute. To do.
Methanol (15 cc) is added to this to precipitate the polymer, which is then filtered. The filtrate was evaporated to dryness, the volume was adjusted to 10 cc with dimethylformamide, and the cyclic trimer was quantified by high performance liquid chromatography.

(5) Acetaldehyde content (AA content) Sample / distilled water = 1 g / 2 cc Nitrogen-substituted glass ampoule was placed in a glass ampoule, the upper part thereof was sealed, extraction treatment was performed at 160 ° C. for 2 hours, and extraction was performed after cooling. Acetaldehyde in the liquid was measured by high sensitivity gas chromatography, and the concentration was expressed in ppm.

(6) Formaldehyde Content (FA Content) 1 g of resin pellets was put into a glass ampoule together with 2 cc of distilled water, the atmosphere was replaced with nitrogen, the upper portion was sealed, and heat-treated at 160 ° C. for 1 hour. After cooling, it is converted into a fluorescent derivative with cyclohexane-1,3-dione and measured by liquid chromatography to determine the FA content. For details, see Analytical Chemistry, Vol.3
4, p. 314 (1985).

(7) Free glycol content of polyester (hereinafter, free ethylene glycol is referred to as "free EG content" and free diethylene glycol is referred to as "free DEG content")

A hexafluoroisopropanol / chloroform mixture 4 of 1.000 g of a sample was placed in an Erlenmeyer flask.
Dissolve in cc, and then add 5 cc of distilled water to homogenize the contents. Heat with hot water bath at about 60 ℃ to distill off the mixed solvent,
Cooling. The residual aqueous phase is filtered using a glass fiber filter. The volume of the filtrate was adjusted to 10 cc with water and quantified by gas chromatography.

(8) Monomer content of polyester containing free aromatic dicarboxylic acid and glycol and dimer content (in the case of PET, monohydroxyethyl terephthalate content (hereinafter referred to as "free MHET content"), bis Hydroxyethyl terephthalate content (hereinafter referred to as "free BHET content"), and bishydroxyethyl terephthalate dimer content (free BHET2
(Quantity content)

300 mg of a sample was mixed with hexafluoroisopropanol / chloroform mixture (volume ratio = 2/3) 3
It is dissolved in cc and diluted with 30 cc of chloroform. Methanol (15 cc) is added to this to precipitate the polymer, which is then filtered. The filtrate was evaporated to dryness, adjusted to a constant volume with 10 cc of dimethylformamide, and quantified by high performance liquid chromatography.

(9) Measurement of Fine Content Using a 10.5 mesh standard sieve according to JIS-Z8801, a 1000 kg sample is sieved, and the amount of fine that has passed through the sieve is weighed to determine the content.

(10) Evaluation of mold stains Polyester was dried with a drier using nitrogen, and a preform was molded with an M-100 injection molding machine manufactured by Meiki Seisakusho at a resin temperature of 290 ° C. The plug part of this preform was heated and crystallized by a home-made cap part crystallization device, and then biaxially stretch blow molded using a LB-01 stretch blow molding machine manufactured by Corpoplast, and subsequently at about 155 ° C. Heat setting was performed for 10 seconds in the set mold to obtain a 500 cc hollow molded body. Stretch blow molding was continuously carried out under the same conditions, and the mold stain was evaluated by the number of moldings until the transparency of the container was impaired by visual observation. In addition, as a sample for haze measurement, 5
The body of the container after continuous molding for 000 times was provided.

(11) Haze (% haze) A sample was cut from the body (wall thickness of about 4 mm) of the hollow molded article of (10) above and measured with a haze meter manufactured by Higashi Seisakusho.

(12) Density increase due to heating of bottle cap part The bottle cap part was heat-treated for 60 seconds by a home-made infrared heater, and a sample was taken from the top surface to measure the density.

(13) Sensory test The hollow container obtained in the above (10) was filled with distilled water at 70 ° C., sealed and held for 30 minutes, cooled to room temperature and allowed to stand at room temperature for 1 month. And so on. Distilled water is used as a blank for comparison. The sensory test was carried out by 10 panelists according to the following criteria, and the average values were compared. (Evaluation criteria) 0: No off-taste or odor 1: Slight difference from blank 2: Slight difference from blank 3: Sensible difference from blank 4: Very large difference from blank feel

(14) Glycol content in treated water (in the case of ethylene glycol, "EG content in water", in the case of diethylene glycol, "DEG content in water") The glycol in the treated water was analyzed by a high sensitivity gas chromatograph method. It was measured.

(15) Content of monomer consisting of aromatic dicarboxylic acid and glycol in treated water and content of dimer (in the case of PET, content of monohydroxyethyl terephthalate (content of MHET in water), content of bishydroxyethyl terephthalate) (BHET content in water) and bishydroxyethyl terephthalate dimer content (BHET dimer content in water) The treated water samples were measured by high performance liquid chromatography.

(16) Amount of fine powder in treated water in the treatment tank (pp
m) Collect 1000 cc of treated water that has passed through the JIS standard 20 mesh filter from the outlet of the treated water in the treatment tank,
100% after filtering with 1G1 glass filter manufactured by Iwaki Glass Co., Ltd.
After drying at ℃ for 2 hours and cooling at room temperature, the weight is measured and calculated.

Example 1 A raw material chip supply port (1) at the upper part of the treatment tank, an overflow discharge port (2) located at the upper limit level of the treated water in the treatment tank, and a discharge of a mixture of polyester chips and treated water at the lower part of the treatment tank. The outlet (3), the treated water discharged from the overflow outlet, and the treated water discharged from the outlet at the bottom of the treatment tank and passed through the drainer (4) are continuous filters having a filter medium made of paper and having a thickness of 30 μm. Piping (6) sent to the water treatment tank again via the fine powder removing device (5), an inlet (7) for these fine powder-removed treated water,
An adsorption tower (8) for adsorbing acetaldehyde, glycol, etc. in treated water from which fine powder has been removed, and a tower-type treatment tank shown in FIG. Was used to water treat the PET chips.

The intrinsic viscosity was 0.75 deciliter / g, the DEG content was 2.3 mol%, and the density was 1.400 g.
/ Cm ³ , cyclic trimer content 0.31% by weight, free E
G content is 8.5 ppm, free DEG content is 1.8 p
pm, free MHET content 10ppm, free BHET
Content 25 ppm, free BHET dimer content 53
ppm, AA content is 5.9 ppm, FA content is 1.
PET chips of 6 ppm were continuously fed into the water treatment tank whose treated water temperature was controlled at 95 ° C at a rate of 50 kg / hour from the supply port (1) at the upper portion of the treatment tank, and the water was discharged from the lower portion of the treatment tank after 5 hours. PET chips were continuously extracted from the outlet (3) at a rate of 50 kg / hour together with the treated water. Further, new ion-exchanged water was supplied from the inlet (9) so that the water constantly overflowed from the overflow outlet (2) of the water treatment tank. EG content and DE in water of treated water discharged from treatment tank after 72 hours of continuous operation
Total G content 15.2ppm, BHET in water
The content is 2.3 ppm, and the MHET content in water is 4.
The content of fine powder was 5 ppm, and the content of fine powder was about 100 ppm.

The PET obtained has a free EG content of 5.3.
ppm, free DEG content is 1.0 ppm, free MHE
T content is 9ppm, free BHET content is 19pp
m, free BHET dimer content 46 ppm, CT content 0.30 wt%, AA content 4.2 ppm, FA
Content is 1.0ppm and fine content is 25ppm
Met.

The haze of the hollow container obtained in (10) was 1.0%, which was excellent in transparency, and the number of moldings until the mold was soiled was 1
There was no problem with 3000 times. The sensory test result was as good as 0.9, and according to the production method of the present invention, PE for hollow moldings, films, sheets, etc., which does not affect the taste of the contents.
It can be seen that a T-chip can be manufactured.

(Example 2) The same PET chip as in Example 1 was used and the same water treatment tank was used as in Example 1 except that treated water having a fine powder amount of about 500 ppm was used. It was The EG content in the treated water and the like were almost the same as in Example 1.

The obtained PET had a free EG content of 4.9.
ppm, free DEG content is 1.0 ppm, free MHE
T content is 11 ppm, free BHET content is 18 pp
m, free BHET dimer content 47 ppm, CT content 0.30 wt%, AA content 3.8 ppm, FA
Content is 1.2ppm and fine content is 150pp
It was m.

The density of the top surface after heating with an infrared heater of the plug portion of the hollow container obtained in (10) was 1.380 g.
/ Cm ³ , haze was 1.4%, which was excellent in transparency, and the number of moldings until the mold was soiled was 15,000, which was not a problem.
The result of the sensory test was as good as 0.8, and according to the production method of the present invention, transparency, heat resistance, excellent long-term continuous moldability, and a hollow molded article, film or sheet which does not affect the taste of the content. It can be seen that a PET chip for such purposes can be manufactured.

Example 3 Intrinsic viscosity was 0.61 deciliter / g, DEG content was 3.5 mol%, and cyclic 3
Content of 0.25% by weight, content of AA is 5.5 pp
m is a polyethylene-2,6-naphthalate-terephthalate copolymer (8 units of ethylene terephthalate units
The water treatment was performed on the chips (containing mol%) by the same treatment method as in Example 1 using the same water treatment tank as in Example 1.

After 72 hours of continuous operation, the total content of the EG content in the treated water and the DEG content in the treated water discharged from the treatment tank was 20.4 ppm, and the free 2,6-naphthalenedicarboxylic acid monoethylene glycol was contained in the treated water. The amount is 4.7
ppm, and the free 2,6-naphthalenedicarboxylic acid diethylene glycol content in the treated water was 2.1 ppm.

The free EG content of the PEN obtained was 7.5.
ppm, free DEG content 1.2 ppm, free 2,
6-naphthalenedicarboxylic acid monoethylene glycol content is 20ppm, free 2,6-naphthalenedicarboxylic acid diethylene glycol content is 30ppm, free 2,6-naphthalenedicarboxylic acid diethylene glycol dimer content is 60ppm, CT content is 0.24 wt
%, AA content was 4.5 ppm.

The haze of the hollow container obtained in (10) was 2.3%, which was excellent in transparency, and the result of the sensory test was 0.
It was 6 and was good.

(Comparative Example 1) Without using the adsorption tower (8) used in Example 1, the part was changed to a direct connection pipe,
Other than that was performed like Example 1. The total content of in-water EG content and in-water DEG content discharged from the treatment tank is about 160 ppm, and the BHET content in water is 130 p.
pm and MHET content in water were 150 ppm. In addition, the free EG of the obtained PET chips after water treatment
Content is 30ppm, Free DEG content is 9.3pp
m, free MHET content 65 ppm, free BHET content 90 ppm, free BHET dimer content 230
ppm, CT content was 0.30 wt% and AA content was 5.8 ppm. The sensory test result of the hollow molded article obtained by the biaxial stretch blow molding in the same manner as in the example was 3.7.
And was very bad.

[0112]

Industrial Applicability The polyester of the present invention is a polyester mainly composed of an aromatic dicarboxylic acid, which is water-treated in a chip form after polycondensation, and has a free glycol content of 30 ppm or less derived from the polyester. Group dicarboxylic acid monoglycol ester content 50ppm
Hereinafter, a free aromatic dicarboxylic acid diglycol ester content of 70 ppm or less is a polyester having a free dimer content of 200 ppm or less comprising an aromatic dicarboxylic acid and a glycol, and by using the polyester of the present invention, A hollow molded article, a sheet-shaped material, a stretched film, and a container made of these materials, which are less likely to cause mold stains during molding, and have excellent transparency, heat resistance, mechanical properties, residual off-taste, and off-flavor and which are excellent in aroma retention And packaging materials can be obtained.

[Brief description of drawings]

FIG. 1 is a schematic view of an apparatus used in the method for producing polyester of the present invention.

[Explanation of symbols]

1 Raw material chip supply port 2 Overflow outlet 3 Polyester chips and treated water outlet 4 drainer 5 Fine powder remover 6 piping 7 Treated water re-introduction port 8 adsorption tower 9 Ion exchange water inlet

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Hirotoshi Sonoda             2-1-1 Katata, Otsu City, Shiga Prefecture Toyobo             Koki Co., Ltd. (72) Inventor Mitsuru Nakata             352-2, Wazunaka, Shiga-cho, Shiga-gun, Shiga Prefecture (72) Inventor Yoshitaka Eto             20 248 Takashiro, Shiga Town, Shiga District, Shiga Prefecture F-term (reference) 4F071 AA45 AA46 AF13 AF30 AF45                       AF54 AG33 AH05 AH19 BA01                       BB06 BB07 BB08 BB09 BC01                       BC04                 4J029 AA03 AB01 AC01 AC02 AD10                       AE01 AE03 BA03 BA04 BA05                       BA10 BB13A BD06A BF09                       BF25 CA02 CA04 CA05 CA06                       CB05A CB06A CB10A CC05A                       CD03 CF15 EA01 EB04A                       FC03 FC05 FC08 FC12 FC14                       KH05

Claims (12)

[Claims] 1. A polyester which has been water-treated in the form of chips after polycondensation, wherein the acid component of the polyester is mainly an aromatic dicarboxylic acid, the free glycol content derived from the polyester is 30 ppm or less, and the free aroma. Group dicarboxylic acid monoglycol ester content 50ppm
Hereinafter, the content of free aromatic dicarboxylic acid diglycol ester is 70 ppm or less, the content of free dimer consisting of aromatic dicarboxylic acid and glycol is 200 ppm or less, and the fine content is 0.1 to 500 ppm. Characteristic polyester. 2. The polyester according to claim 1, wherein the fine content is 150 ppm or less. 3. The polyester according to claim 1, wherein the fine content is 25 ppm or less. 4. A polyester wherein the main aromatic dicarboxylic acid is terephthalic acid and the main glycol is ethylene glycol.
Or the polyester described in 3. 5. The polyester according to claim 1, 2 or 3, wherein the main aromatic dicarboxylic acid is 2,6-naphthalenedicarboxylic acid and the main glycol is ethylene glycol. 6. The acid component of the polyester is mainly terephthalic acid, the glycol component is mainly ethylene glycol, the intrinsic viscosity is 0.68 to 0.90 deciliter / g, the density is 1.37 g / cm ³ or more, and free. Ethylene glycol content of 15 ppm or less, free diethylene glycol content of 5 ppm or less, free monohydroxyethyl terephthalate content of 40 ppm or less, free bishydroxyethyl terephthalate content of 50 ppm or less, free bishydroxyethyl terephthalate 2 amount Body content is 100 ppm or less, The polyester of Claim 1, 2, 3, 4 or 5. 7. Polyester is formed into chips after polycondensation, and the content of glycol derived from the polyester, the content of aromatic dicarboxylic acid monoglycol ester, and the aromatic dicarboxylic acid diglycol ester in a treatment tank is set. 2. Each of the above is treated with treated water having a content of 100 ppm or less.
The polyester according to 2, 3, 4, 5 or 6. 8. The polyester is formed into a chip shape after polycondensation and treated with treated water satisfying the following conditions (a) and (b) in a treatment tank. The polyester according to 1, 2, 3, 4, 5, 6 or 7. (A) Temperature 40 to 120 ° C. (b) Treated water including wastewater from the treatment tank 9. The polyester is formed into a chip shape after polycondensation and treated with treated water satisfying the following condition (c) in a treatment tank. The polyester according to 3, 4, 5, 6, 7 or 8. (C) Treated water having a polyester fine powder content of 1000 ppm or less 10. The method according to claim 1, 2, 3, 4, 5, 6, 7,
A hollow molded article obtained by molding the polyester according to 8 or 9. 11. The method according to claim 1, 2, 3, 4, 5, 6, 7,
A sheet-like material, which is formed by molding the polyester according to 8 or 9. 12. A stretched film obtained by stretching the sheet-like material according to claim 11 in at least one direction.