JP2002332340A - Production method for polyester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyester the chips of which hardly stain a treating tank or a pipeline when treated with water and which hardly causes mold staining when molded and gives a bottle having a good transparency and exhibiting a good crystallization at a plug section. SOLUTION: This polyester is produced by a method wherein chips of a polyester mainly comprising repeating ethylene terephthalate units are treated with water in a treating tank. The highest melting peak temperature of fines and/or a filmy product contained in the polyester is 265 deg.C or lower. One of the content of the fines, the content of the filmy product, and the sum of contents of the fines and the filmy product is 300 ppm or lower.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing polyester used for molding bottles, films, sheets and the like. The present invention relates to a method for producing a polyester having excellent crystallization controllability.

[0002]

2. Description of the Related Art Polyesters such as polyethylene terephthalate are excellent in both mechanical properties and chemical properties, and therefore have high industrial value, and include fibers, films, sheets, and the like.
Widely used as bottles.

[0003] As materials for containers such as seasonings, oils, beverages, cosmetics, and detergents, various resins are employed depending on the type of filling content and the purpose of use.

[0004] Among these, polyester is excellent in mechanical strength, heat resistance, transparency and gas barrier properties, and therefore is particularly suitable as a material for containers for filling beverages such as juices, soft drinks and carbonated drinks. .

[0005] Such 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, stretched and blow molded, and then bottled. Heat treatment of body (heat set)
Then, it is general that the plug portion of the bottle is heat-treated (the plug portion is crystallized) if necessary.

However, conventional polyesters contain oligomers such as cyclic trimers, 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 easily generated.

Further, the polyester contains acetaldehyde which is a by-product. When the content of acetaldehyde in the polyester is large, the content of acetaldehyde in the material of a container or other packaging formed therefrom also increases, which affects the flavor and odor of the beverage or the like filled in the container or the like. Therefore, various measures have conventionally been taken to reduce the acetaldehyde content in the polyester.

In recent years, containers made of polyester, mainly polyethylene terephthalate, have been used for mineral water and water.
It has been used as a container for low-flavor beverages such as long tea. In the case of such beverages, these beverages are generally heat-filled or sterilized by heating after filling, but reducing the acetaldehyde content of the beverage container alone does not improve the flavor or odor of these contents. I understand.

In addition, for the metal can for beverages, a metal plate coated with a polyester film having ethylene terephthalate as a main repeating unit is used for the purpose of simplifying the process, improving hygiene and preventing pollution. The method of making cans has been adopted. Also in this case, the contents are heat-sterilized at a high temperature after filling, and it has been found that the flavor and odor of the contents are not improved even if a film having a low acetaldehyde content is used.

As a method for solving such a problem,
JP-A-3-47830 discloses a polyethylene terephthalate.
A method for water treatment of wastewater is disclosed.

However, when this method is carried out industrially, the use of distilled water as a treatment water is disadvantageous in terms of cost. It is common to use water. However, when water treatment is performed using industrial water, there is a problem that crystallization during molding is often too early, resulting in a bottle having poor transparency. Further, there is also a problem that shrinkage of the plug portion due to crystallization of the plug portion does not fall within the standard, resulting in poor capping.

According to the study of the present inventors, this is due to the fact that at the stage of water treatment, when the content of metal-containing substances such as sodium, magnesium, calcium and silicon dioxide contained in industrial water is larger than a certain value, Metal-containing substances such as oxides and hydroxides of these metals float and precipitate in the treatment water, and further adhere to the walls of the treatment tanks and pipes, which adhere to and penetrate the polyester chips, and are formed during molding. It was found that the crystallization of was accelerated, resulting in a bottle with poor transparency. Further, there have been problems such as a metal-containing substance clogging the piping and making the cleaning of the processing tank and the piping difficult.
In the water treatment stage, fines (resin fine powder) adhering to the polyester chips float and precipitate in the treated water and adhere to the walls of the treatment tanks and pipes, causing clogging of the pipes, There have also been problems such as difficulty in cleaning the surface.

Therefore, in order to obtain a water-treated polyester which gives a molded article having good transparency, ion-exchanged water obtained by treating industrial water with an ion-exchange treatment apparatus is used, and polyester fine powder in a treatment tank is used. The polyester is treated with water by controlling the amount and other particles to a certain concentration or less, but sometimes even in this case, only a molded article with poor transparency may be obtained, or after crystallization of the plug part. There was a problem that the cap dimensions did not conform to the standard, resulting in poor capping.

[0014]

SUMMARY OF THE INVENTION An object of the present invention is to solve the problems of the prior art, and to reduce the contamination of a treatment tank and piping during the water treatment of polyester chips, and to further reduce the mold during molding. It is an object of the present invention to provide a polyester which is less likely to generate stains and further has good transparency of a bottle and crystallization of a plug portion.

[0015]

Means for Solving the Problems To achieve the above object, a method for producing a polyester according to the present invention is directed to a method for producing a polyester in which a polyester chip whose main repeating unit is ethylene terephthalate is treated in a treatment tank with water. In the method, the polyester contains fine and / or fine particles.
Alternatively, the melting peak temperature on the highest temperature side of the melting peak temperature of the film is 265 ° C. or less, and the fine content,
The content of either the film content or the total content of the fine content and the film content is 300
It is characterized in that the polyester which is less than ppm is treated with water.

Here, the fine is defined by JIS-Z8801.
Means fine polyester powder that has passed through a sieve with a 1.7 mm nominal size wire mesh, and film-like material remained on a 5.6 mm nominal size wire mesh sieve according to JIS-Z8801. Of the polyester, a film-like material from which two or more chips have been fused or a chip-like material that has been cut larger than a normal shape is removed, and the content of these is measured by the following measurement method. .

As described below, the melting point of the fine or film-like material is measured using a differential scanning calorimeter (DSC), and the melting peak temperature of the DSC is called the melting point. The melting peak representing this melting point is composed of one or more melting peaks. In the present invention, when there is one melting peak, the peak temperature and the melting peak are determined. When there are a plurality of melting peaks, the highest one of the plurality of melting peaks is referred to as "the highest peak of the melting peak temperature of the fine or film-like material." In the examples and the like, the melting point is referred to as the “melting point of fine” and the “melting point of film”.

In the method for producing a polyester according to the present invention, the polyester obtained by the above-mentioned production method is subjected to a fine and / or film removing step for removing fine and / or film-like substances as required, and then a polyolefin resin member is produced. Contacting with at least one member selected from the group consisting of a member made of polyamide resin and a member made of polyacetal resin.

In this case, the density of the polyester can be 1.37 g / cm ³ or more. In this case, the intrinsic viscosity of the polyester is 0.55 to
It can be 1.30 deciliters / gram. In this case, the content of the polyester cyclic trimer can be 0.50% by weight or less.

In this case, the particle size of the treated water discharged from the treatment tank and returned to the treatment tank is 1 to 40 μm.
Water treatment can be performed while maintaining the number of particles of m at 100,000 particles / 10 ml or less.

[0021]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester according to the present invention is a polyester whose main repeating unit is ethylene terephthalate, and is preferably a linear polyester containing at least 85 mol% of ethylene terephthalate units, More preferably 90 mol% or more, particularly preferably 95%
It is a linear polyester containing the above.

The dicarboxylic acid as a copolymer component used when the polyester is a copolymer includes:
Aromatic dicarboxylic acids such as isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, diphenoxyethanedicarboxylic acid, and functional derivatives thereof, p-oxybenzoic acid, oxycaproic acid, etc. Oxyacids and their functional derivatives, adipic acid, sebacic acid, succinic acid, glutaric acid, dimer acids and other aliphatic dicarboxylic acids and their functional derivatives, cyclohexanedicarboxylic acids and other alicyclic dicarboxylic acids and their functional Derivatives and the like.

Glycols as copolymer components used when the polyester is a copolymer include diethylene glycol, trimethylene glycol, tetramethylene glycol, neopentyl glycol and the like. Alicyclic glycols such as aliphatic glycol and cyclohexanedimethanol, polyalkylene glycols such as polyethylene glycol, polypropylene glycol and polybutylene glycol, bisphenol A, bisphenol And aromatic glycols such as alkylene oxide adducts of thiol A.

Further, as the polyfunctional compound as a copolymer component used when the polyester is a copolymer, trimellitic acid, pyromellitic acid and the like can be mentioned as an acid component. Glycerin and pentaerythritol can be mentioned as components. The amount of the above-mentioned copolymer component to be used must be such that the polyester maintains a substantially linear shape. Further, a monofunctional compound such as benzoic acid or naphthoic acid may be copolymerized.

The above polyester can be produced by a conventionally known production method. That is, in the case of PET, terephthalic acid is directly reacted with ethylene glycol and, if necessary, other copolymerization components to distill water and esterify, followed by polycondensation under reduced pressure. Law,
Alternatively, it is produced by a transesterification method in which dimethyl terephthalate is reacted with ethylene glycol and, if necessary, other copolymerization components to remove methyl alcohol and transesterify, followed by polycondensation under reduced pressure. . If necessary, solid-state polymerization may be performed in order to increase the intrinsic viscosity and reduce the acetaldehyde content and the like. In order to promote crystallization before solid-phase polymerization, the melt-polymerized polyester may be heated and then crystallized after moisture absorption, or steam may be directly blown onto the polyester chip for heat crystallization.

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 performed in one step or may be performed in multiple steps. The solid-state polymerization reaction can be performed in 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.

Hereinafter, an example of a preferable production method in a continuous system will be described using polyethylene terephthalate as an example.

First, the case of producing a low polymer by an esterification reaction will be described. A slurry containing 1.02 to 1.5 moles, preferably 1.03 to 1.4 moles, of ethylene glycol per 1 mole of terephthalic acid or an ester derivative thereof is prepared, and the slurry is subjected to an esterification reaction step. Continuously.

In the esterification reaction, water or alcohol produced by the reaction is rectified under a condition in which ethylene glycol is refluxed using a multistage apparatus in which at least two esterification reactors are connected in series. It is carried out while removing the system outside the column. The temperature of the first stage esterification reaction is 240 ~
270 ° C, preferably 245-265 ° C, pressure 0.2
３3 kg / cm ² G, preferably 0.5-2 kg / cm ²
G. The temperature of the final esterification reaction is usually 25.
The temperature is 0 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.
It is 3 kg / cm ² G. When the reaction is carried out in three or more stages, the reaction conditions for the esterification reaction in the intermediate stage are the above-mentioned first conditions.
This is a condition between the reaction condition of the stage and the reaction condition of the final stage. The increase in the conversion of these esterification reactions is preferably distributed smoothly at each stage. Finally, the esterification reaction rate is 90% or more, preferably 93%.
It is desirable to reach the above. A low-order condensate having a molecular weight of about 500 to 5,000 is obtained by these esterification reactions.

When terephthalic acid is used as a raw material, the above 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 and benzyldimethylamine, tetraethylammonium hydroxide,
When a small amount of a quaternary ammonium hydroxide such as n-butylammonium and trimethylbenzylammonium hydroxide and a basic compound such as lithium carbonate, sodium carbonate, potassium carbonate and sodium acetate are added, the reaction of polyethylene terephthalate is reduced. It is preferable because the ratio of the dioxyethylene terephthalate component unit in the chain can be kept at a relatively low level (5 mol% or less based on all diol components).

Next, when a low polymer is produced by a transesterification reaction, 1.1 to 1.6 moles, preferably 1.2 to 1.5 moles of ethylene glycol are added to 1 mole of dimethyl terephthalate. Is prepared and continuously supplied to the transesterification step.

The transesterification is carried out by using an apparatus in which one or two transesterification reactors are connected in series under conditions where ethylene glycol is distilled back, and the methanol produced by the reaction is passed through a rectification column. Perform while removing outside the system. The temperature of the first-stage transesterification reaction is 180 to 250 ° C, preferably 200 to 240 ° C. The temperature of the final transesterification reaction is usually 230 to 270 ° C., preferably 24 to 270 ° C.
0 to 265 ° C., and as a transesterification catalyst, Zn,
Fatty acid salts such as Cd, Mg, Mn, Co, Ca, and Ba;
Carbonate, Pb, Zn, Sb, Ge oxide or the like is used. By these transesterification reactions, the molecular weight is about 200 to 500.
A low degree of condensate is obtained.

Next, the obtained low-order condensate is supplied to a multi-stage liquid phase condensation polymerization step. The polycondensation reaction conditions are as follows: the reaction temperature of the first stage polycondensation is 250 to 290 ° C, preferably 260 to 280 ° C, and the pressure is 500 to 20 Torr.
r, preferably 200 to 30 Torr, and the temperature of the final polycondensation reaction 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 the reaction is carried out in three or more stages, the reaction conditions for the polycondensation reaction in the intermediate stage are those between the above-mentioned first-stage reaction conditions and the last-stage reaction conditions. It is preferred that the degree of increase in the intrinsic viscosity reached in each of these polycondensation reaction steps be distributed smoothly.

The polycondensation reaction is performed using a polycondensation catalyst.
As the polycondensation catalyst, a compound of Ge, Sb, Ti, or Al is used.
It is also convenient to use a mixed catalyst of a compound and an Al compound, a Sb compound and a Ti compound, or a Sb compound and a Ge compound. These compounds are added to the reaction system as a powder, an aqueous solution, an ethylene glycol solution, a slurry of ethylene glycol, and the like.

As the Ge compound, amorphous germanium dioxide, crystalline germanium dioxide powder or a slurry of ethylene glycol, a solution in which crystalline germanium dioxide was dissolved by heating in water, or ethylene glycol was added thereto and heat-treated. A solution or the like is used. In particular, in order to obtain the polyester used in the present invention, it is preferable to use a solution obtained by heating and dissolving germanium dioxide in water or a solution obtained by adding ethylene glycol to the solution and heating. These polycondensation catalysts can be added during the esterification step. When a Ge compound is used, the amount of the Ge compound used is 10 to 150 ppm, preferably 13 to 100 ppm, more preferably 15 to 70 ppm as the amount of Ge remaining in the polyester.
pm.

Examples of the Ti compound include tetraalkyl titanates such as tetraethyl titanate, tetraisopropyl titanate, tetra-n-propyl titanate and tetra-n-butyl titanate, and partial hydrolysis thereof. Products, titanyl oxalate, titanyl ammonium oxalate, sodium titanyl oxalate, potassium titanyl oxalate, titanyl calcium oxalate, titanyl strontium oxalate, and the like, titanium trimellitate, titanium sulfate, titanium chloride, and the like. The Ti compound is formed polymer
It is added so that the remaining amount of Ti therein is in the range of 0.1 to 10 ppm.

As the Sb compound, antimony trioxide,
Antimony acetate, antimony tartrate, antimony potassium tartrate, antimony oxychloride, antimony glycolate
And antimony pentoxide, triphenylantimony and the like. The Sb compound is added so that the residual amount of Sb in the resulting polymer is in the range of 50 to 250 ppm.

As the Al compound, aluminum formate, aluminum acetate, aluminum propionate,
Carboxylates such as aluminum oxalate, oxides, inorganic salts such as aluminum hydroxide, aluminum chloride, aluminum hydroxide chloride, and aluminum carbonate; aluminum alkoxides such as aluminum methoxide and aluminum ethoxide; and aluminum acetylacetonate. To
Examples thereof include aluminum chelate compounds with aluminum acetyl acetate and the like, organoaluminum compounds such as trimethylaluminum and triethylaluminum, and partially hydrolyzed products thereof. Of these, 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.

In the present invention, an alkali metal compound or an alkaline earth metal compound may be used in combination.
The alkali metal compound or alkaline earth metal compound is
Carboxylates such as acetates of these elements, alkoxides and the like can be mentioned, and are added to the reaction system as powders, aqueous solutions, ethylene glycol solutions and 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.

Various P compounds can be used as stabilizers. Examples of the P compound used in the present invention include phosphoric acid, phosphorous acid, and derivatives thereof. Specific examples include phosphoric acid, trimethyl phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate, monomethyl phosphate, dimethyl phosphate, monobutyl phosphate, dibutyl phosphate, and dibutyl phosphate. Phosphoric acid, trimethyl phosphite, triethyl phosphite, tributyl phosphite, etc., which may be used alone or in combination of two or more.
The P compound is 1 to 10 as a residual amount of P in the produced polymer.
It can be added at any stage of the polyester production reaction step so as to be in the range of 00 ppm.

Further, when a low acetaldehyde content or a low cyclic trimer content is required such as a low-flavor beverage heat-resistant container or a film for the inner surface of a metal can for beverage, etc. The obtained melt-polycondensed polyester is subjected to solid-state polymerization. The polyester is subjected to solid-state polymerization by a conventionally known method. First, the polyester to be subjected to solid-state polymerization is treated under an inert gas or under reduced pressure or under an atmosphere of steam or an inert gas containing steam.
It is pre-crystallized by heating at a temperature of 00 to 210 ° C. for 1 to 5 hours. Then, under an inert gas atmosphere or reduced pressure, 19
The solid state polymerization is carried out at a temperature of 0 to 230 ° C. for 1 to 30 hours.

The intrinsic viscosity of the polyester according to the present invention in which the main repeating unit is composed of ethylene terephthalate is 0.55 to 1.30 deciliter / gram, preferably 0.57 to 1.20 deciliter / gram. It is preferably in the range of 0.60 to 0.90 deciliter / gram. If the intrinsic viscosity is less than 0.55 deciliter / gram, the mechanical properties of the obtained molded article and the like are poor. On the other hand, if it exceeds 1.30 deciliters / gram, the resin temperature rises during melting by a molding machine or the like, and thermal decomposition becomes severe, so that free low-molecular-weight compounds that affect fragrance retention increase, Causes problems such as coloring of yellow.

The shape of the polyester chip may be any of a cylinder type, a square type, a spherical shape, a flat plate shape and the like.
The average particle size is usually 1.5 to 5 mm, preferably 1.
6 to 4.5 mm, more preferably 1.8 to 4.0 mm
Range. For example, in the case of a cylinder type, it is practical that the length is about 1.5 to 4 mm and the diameter is about 1.5 to 4 mm. In the case of spherical particles, the maximum particle diameter is 1.1 to 2.0 times the average particle diameter, and the minimum particle diameter is 0.1 to 2.0 times the average particle diameter.
It is practical that it is 7 times or more. Further, the weight of the chip is practically in the range of 15 to 30 mg / piece.

The acetaldehyde content of the polyester according to the present invention is 10 ppm or less, preferably 8 pp.
m or less, more preferably 5 ppm or less, and the formaldehyde content is 7 ppm or less, preferably 6 ppm or less, more preferably 4 ppm or less. When the content of acetaldehyde is 10 ppm or more and the content of formaldehyde is 7 ppm or more, the flavor and smell of the contents such as containers molded from the polyester composition become poor.

The amount of diethylene glycol copolymerized in the polyester according to the present invention is 1.0 to 5.0 mol%, preferably 1.3 to 4.5 mol% of the glycol component constituting the polyester. Mol%, more preferably 1.5 to
4.0 mol%. Diethylene glycol content is 5.0
If it exceeds mol%, the thermal stability becomes poor, the molecular weight decreases during molding, and the acetaldehyde content and the formaldehyde content increase, which is not preferable. When the content of diethylene glycol is less than 1.0 mol%, the transparency of the obtained molded article is deteriorated.

Further, the cyclic 3 of the polyester according to the present invention
Content of the monomer is 0.50% by weight or less, preferably 0.4% by weight or less.
It is at most 5% by weight, more preferably at most 0.40% by weight. When molding a heat-resistant hollow molded article or the like from the polyester of the present invention, heat treatment is performed in a heating mold.
When the content of the monomer is 0.50% by weight or more,
Adhesion of the oligomer to the surface of the heating mold is rapidly increased, and the transparency of the obtained hollow molded article or the like is extremely deteriorated.

The polyester is used in order to prevent mold contamination and the like due to the adhesion of oligomers such as cyclic trimers to the inner surface of the mold, the gas outlet of the mold, and the exhaust pipe during molding. After the melt polycondensation or solid phase polymerization, a contact treatment with water is performed.

As a method of the contact treatment with water, a method of immersion in water may be mentioned. The time for performing the contact treatment with water 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. ° C, more preferably 50 to 120 ° C.

After the melt-polycondensed polyester is formed into chips, it is transported in a transport pipe to a storage silo, or transported to the next step such as a solid phase polymerization step or a water treatment step. The solid-phase polymerized polyester chips are similarly transported to the next step or a silo. When such chips are transported by, for example, a forced low-density transport method using air, a large impact force is applied to the surface of the polyester chips by collision with the piping, and as a result, fine or film-like materials are produced. Occurs in large quantities. Some of the fines and most of the film thus formed have a very high melting point exceeding 265 ° C. Also, solid-phase polymerization using a rotary solid-state polymerization apparatus, or when using a feeding device that applies an impact force or shear force to the polyester chip as a transportation method to the next step, as described above Fine or film-like substances having a melting point exceeding 265 ° C. are generated. This is presumably because the chip generates heat due to a large force such as an impact force applied to the chip surface, and at the same time, the oriented crystallization of polyester occurs on the chip surface, resulting in a dense crystal structure.

When the fine or film-like polyester having a melting point exceeding 265 ° C. as described above is subjected to solid phase polymerization treatment with polyester chips or water treatment, these melting points are higher than before the treatment. It will be even higher. Fine and film-like materials having a melting point of 265 ° C. or lower but considerably higher than the normal melting point can have a melting point exceeding 265 ° C. by these treatments. This is presumed to be due to the fact that the crystal structure changes to a denser crystal structure by these treatments.

When the polyester containing such a high melting point fine or film-like material is molded under ordinary molding conditions, the crystals do not completely melt during melt molding and remain as crystal nuclei. As a result, the crystallization rate during heating of the obtained molded body is increased, and the crystallization of the plug portion of the hollow molded container becomes excessive, so that the shrinkage amount of the plug portion does not fall within the specified value range. Poor capping of the plug part causes leakage of the contents or whitening of the preform for hollow molding, so that normal stretching is impossible, thickness unevenness occurs, and the crystallization speed is high, which is obtained. The transparency of the hollow molded article deteriorates, and the fluctuation of the transparency also increases.

In the present invention, the melting point of fine or the like is measured by a differential scanning calorimeter (DSC) as described below, and the melting peak temperature of the DSC is called the melting point as described above. The melting peak representing this melting point is composed of one or more melting peaks. In the present invention, when there is one melting peak, the peak temperature is determined by:
When there are a plurality of melting peaks, the highest one of the plurality of melting peaks is set to the highest melting peak temperature of the fine or film-like material. The peak temperature on the side is referred to as "the melting point of fine" and "the melting point of the film" in Examples and the like.

In the present invention, the highest peak temperature of the melting peak temperature of the fine and / or film-like material contained in the polyester is 265 ° C. or less, and the fine content and the film-like material content are different. Another object of the present invention is to solve the above problem by treating a polyester having a total content of fine content and film content of 300 ppm or less with water.

The fine content, the content of the film-like material, or the total content of the fine content and the content of the film-like material is preferably 200 pp.
m, preferably 100 ppm or less, more preferably 50 ppm or less.

From the polyester, fine and / or fine peaks having a peak temperature of the highest melting peak temperature exceeding 265 ° C.
Alternatively, as a method for separating and removing the film-like material, the following method is exemplified. That is, when the molten polycondensed polyester is subjected to water treatment, the polyester is treated with a vibrating sieve and an airflow classifier using an air flow, a gravity classifier, etc. Is treated with a vibrating sieve, an airflow classifier using an air flow, a gravity classifier, etc., which are separately installed immediately before the solid phase polymerization step and immediately before the water treatment step.

The following methods can be used to prevent fine and / or film-like materials having a melting peak temperature higher than 265 ° C. at the highest melting peak temperature. . That is, the polyester is formed into chips by a method in which the molten polyester is extruded into water from a die after the melt polycondensation and cut in water, or extruded into the atmosphere, and then immediately cut while cooling with cooling water, and then formed into chips. After draining the chips, the vibrating sieve process and the air flow classification process using an air stream are used to remove chips, fines, and film-like objects of a shape other than the specified size, and to use a plug transport system, a vortex air transport system, or a bucket conveyor transport system. To the storage tank. The removal of chips from the tank can be done with a screw-type filter.
In the same way as described above, transport to the next step is carried out by the plug transport method, vortex type transport method or bucket type conveyor transport method, and air flow classification by air flow immediately before the solid state polymerization step and water treatment step. A fine removal process is performed by providing a process or a vibrating sieving process. Further, the melt polycondensed polyester which has been subjected to the above-mentioned fine or film-like material removal treatment is subjected to an air flow classification step by an air flow immediately before the solid phase polymerization step, or a vibratory sieving step, etc. After removal, it can be directly fed into the solid phase polymerization step. When transporting melt-polycondensed prepolymer chips to solid-state polymerization equipment or transporting polyester chips after solid-phase polymerization to a sieving process, a water treatment process, a storage tank, etc., most of these transportations are plugs The transport method, vortex type transport method and bucket type conveyor transport method are adopted, and chips are extracted from the crystallization apparatus or solid state polymerization reactor using a screw feeder. Use a device that can minimize the impact with other equipment and transportation piping.

The following is an example of a method for industrially performing water treatment, but the method is not limited thereto. The processing method may be either a continuous method or a batch method, but the continuous method is preferable for industrial use.

In the case of treating the polyester chips with water in a batch system, a silo-type treatment tank may be used. That is, the chips of polyester are received in a silo in a batch system and water treatment is performed. Alternatively, it is also possible to receive a polyester chip in a rotating cylindrical processing tank and perform water treatment while rotating the chip, thereby making contact with water more efficient.

In this case, the fine and / or film-like material is removed from the molten polycondensation polyester and then the fine and / or film-like material is removed from the polyester obtained by solid-phase polymerization or the polyester after the solid-phase polymerization. Into the processing tank
Fill and fill the treated water, the treated water circulates continuously or intermittently (may be collectively referred to as continuous) as necessary, and discharges some of the treated water continuously or intermittently. Supply additional new treated water.

When the polyester chips are to be continuously treated with water, the polyester chips which have been subjected to a fine and / or film-like removal treatment continuously or intermittently in the tower-type treatment tank in the same manner as described above are placed on the top. Water can be treated by receiving water more continuously and co-currently or counter-currently.

When water is used for treating polyester chips industrially, natural water (industrial water) or waste water is often reused because of the large amount of water used for the treatment. Normally, this natural water is collected from river water, groundwater, or the like, and refers to water that has been subjected to treatment such as sterilization and removal of foreign substances without changing the shape of water (liquid). In general, natural water used industrially is derived from nature, inorganic particles and bacteria represented by clay minerals such as silicates and aluminosilicates, bacteria, etc., and has origins in spoiled plants and animals. Contains a lot of organic particles. When water treatment is performed using such natural water, particles adhere and permeate into polyester chips to form crystal nuclei, and the transparency of a hollow molded container using such polyester chips becomes extremely poor.

Therefore, whether the water treatment method is a continuous method or a batch method, the number of particles having a particle size of 1 to 25 μm existing in water introduced from outside the system is represented by X, When the content of sodium is N, the content of magnesium is M, the content of calcium is C, and the content of silicon is S, water treatment is performed by satisfying at least one of the following (1) to (5). It is desirable to do. 1 ≦ X ≦ 50000 (pieces / 10 ml) (1) 0.001 ≦ N ≦ 1.0 (ppm) (2) 0.001 ≦ M ≦ 0.5 (ppm) (3) 0.001 ≦ C ≦ 0 0.5 (ppm) (4) 0.01 ≤ S ≤ 2.0 (ppm) (5)

By setting any of the number of particles in the water to be introduced into the water treatment tank and the content of sodium, magnesium, calcium, and silicon within the above ranges, a metal such as an oxide or a hydroxide called a scale is prepared. Contained substances float in the treated water, precipitate, adhere to the walls of the processing tank and piping, and adhere to and penetrate the polyester chips, which promotes crystallization during molding, resulting in poorly transparent bottles. Can be prevented. Particle size 1 used for water treatment below
A method for obtaining water containing 1 to 50,000 particles / 10 ml of particles having a particle size of ２５25 μm will be exemplified.

As a method for reducing the number of particles in water to 50000 particles / 10 ml or less, an apparatus for removing particles is installed at at least one place in a process until natural water such as industrial water is supplied to the treatment tank. Preferably, from the natural water sampling port to the processing tank including the above-mentioned processing tank, piping returning the water drained from the processing tank to the processing tank again, a fine removal device, and other auxiliary equipment necessary for water treatment. A device for removing particles is installed between them, and the particle size of
The content of particles of ２５25 μm is 1 to 50,000 particles / 10 m
It is preferably 1. Examples of the device for removing particles include a filter-filtration device, a membrane filtration device, a sedimentation tank, a centrifugal separator, and a foam entrainer. For example, a filter
If it is a filtration device, a belt filter system is used as a system,
Filtration devices such as a bag filter system, a cartridge filter system, a screen filter system, and a centrifugal filtration system may be used. Above all, for continuous operation, a belt filter
A filtration device of a system, a centrifugal filtration system, a bag filter system, or a screen filter system is suitable. In the case of a belt filter type filtration device, examples of the filter medium include paper, metal, cloth, and the like. Also, in order to efficiently remove particles and flow the treated water, the size of the filter is 5 to 5.
100 μm, preferably 10 to 70 μm, more preferably 15 to 40 μm.

In order to reduce the amount of sodium, magnesium, calcium and silicon in water from outside the system to the above-mentioned range, at least one or more places of sodium, magnesium, calcium and calcium in the process until industrial water is sent to the treatment tank. An apparatus for removing silicon is installed. Further, a filter is provided to remove clay minerals such as silicon dioxide and aluminosilicate which have become particulate. Examples of an apparatus for removing sodium, magnesium, calcium, and silicon include an ion exchange apparatus and an ultrafiltration apparatus.

The water introduced from outside the system may be introduced directly into the water treatment tank, or may be introduced into the water treatment tank after being mixed with the recycled water in the recycled water storage tank or the piping for sending the recycled water. Is also good.

Regardless of whether the water treatment method is continuous or batch, if all or most of the treated water discharged from the treatment tank is converted into industrial wastewater, a large amount of fresh water is required. In addition, there is a concern about the impact on the environment due to increased wastewater volume. That is, at least a part of the treated water discharged from the treatment tank is returned to the water treatment tank and reused, thereby reducing the required amount of water and reducing the effect on the environment by increasing the amount of wastewater. If the wastewater returned to the water treatment tank maintains a certain temperature,
The heating amount of the treated water can be reduced.

However, the treated water discharged from the treatment tank includes:
Fine or film-like material that has already adhered to the polyester chips at the stage of receiving the polyester chips into the treatment tank and has not been removed by the above-mentioned water washing treatment, or is generated by friction between the polyester chips or the treatment tank wall during the water treatment. Polyester fine and film-like materials are included.

Therefore, when the treated water discharged from the treatment tank is returned to the treatment tank and reused, the content of fine or film-like substances contained in the treated water in the treatment tank gradually increases. For this reason, fine or film-like substances contained in the treated water may adhere to the treatment tank wall or the pipe wall, and clog the pipe.

The fine or film-like material contained in the treated water adheres again to the polyester chip, and thereafter, the fine or film-like material adheres to the polyester chip by the electrostatic effect at the stage of drying and removing the water. Therefore, even if fine or film-like substances are removed after drying, the removal becomes difficult. Since the fine or film-like material has a crystallization promoting effect, the crystallinity of the polyester is promoted, resulting in a bottle having poor transparency, and the degree of crystallinity at the time of crystallization of the plug becomes excessive. The dimensions of the plug do not meet the standard, resulting in poor capping of the plug.

Therefore, in the present invention, at least a part of the particles discharged from the water treatment tank is returned to the treatment tank again, and the particle diameter present in the treated water to be reused is 1 to 40 μm.
m of particles 100,000 particles / 10 ml or less, preferably 80,000 particles / 10 ml or less, more preferably 500,000 particles / 10 ml or less.
It is desirable to keep the number at or below 00/10 ml. Here, the treated water returned to the treatment tank and reused in this way is referred to as recycled water.

The particle size of the recycled water is 1 to 40
A method for reducing the number of particles of μm to 100,000 / 10 ml or less will be exemplified, but the present invention is not limited thereto. The number of particles having a particle size of 1 to 40 μm
As a method of reducing the amount of particles to 10 ml or less, an apparatus for removing particles is provided at at least one place in a process until the treated water discharged from the treatment tank is returned to the treatment tank again. Examples of the device for removing particles include a filter-filtration device, a membrane filtration device, a sedimentation tank, a centrifugal separator, and a foam entrainer. For example, in the case of a filter-filtration apparatus, examples of the method include a filtration apparatus such as an automatic self-cleaning method, a belt filter method, a bag filter method, a cartridge filter method, and a centrifugal filtration method. Above all, a belt filter system, a centrifugal filtration system, and a bag filter system are suitable for continuous operation. In the case of a belt filter type filtration device, examples of the filter medium include paper, metal, cloth, and the like. Further, in order to efficiently remove particles and flow the treated water, the size of the mesh of the filter is 5 to 100 μm, preferably 5 to 70 μm, and more preferably 5 to 40 μm.
Is good.

The polyester chips subjected to the water treatment are drained by a draining device such as a vibrating sieve or a siemon cutter and transferred to a drying step. Naturally, the water separated from the polyester chips by the drainer is a filter-type filter,
It is sent to a fine or film removing device such as a centrifuge and can be used again for water treatment.

For drying the polyester chips, a commonly used drying treatment of the polyester chips can be used. As a method for continuous drying, a hopper-type through-air dryer that supplies a polyester chip from the upper portion and vents the drying gas from the lower portion is usually used. As a method of reducing the amount of drying gas and drying efficiently, a rotary disk type continuous dryer is selected, and while supplying a small amount of drying gas, heating steam, heating medium, etc. are supplied to the rotating disk and the outer jacket The dried granular polyester chips can be dried indirectly.

As a dryer for drying in a batch system, a double cone type rotary dryer is used, and drying can be performed under vacuum or while passing a small amount of drying gas under vacuum. Alternatively, the drying may be performed while passing a drying gas under atmospheric pressure. As the dry gas, atmospheric air may be used, but dry nitrogen and dehumidified air are preferred from the viewpoint of preventing a reduction in molecular weight due to hydrolysis or thermal oxidative decomposition of the polyester.

The water-treated polyester obtained by the production method of the present invention can be used to increase the rate of crystallization of a molded article obtained therefrom, and to suppress the fluctuation thereof, to make a member made of a polyolefin resin, a member made of a polyamide resin, The contact treatment can be performed with a member made of at least one resin selected from the group consisting of polyacetal resin members (hereinafter, may be abbreviated as "thermoplastic resin").

The polyester chips that have been subjected to the water treatment step are more brittle than the chips before the contact treatment with water.
For example, using a rotary feeder such as a rotary feeder that applies a large impact force to the surface of a polyester chip or a forced low-density transport system using air, a polyolefin resin member, a polyamide resin Parts, polyaceta
When transporting through the transportation pipe to the contact treatment step of contacting at least one resin member selected from the group consisting of resin members, fine or film-like substances are generated in a very large amount, The amount can sometimes be 1000 ppm or more based on the polyester chips.
In particular, the longer the contact processing time or the higher the processing temperature, the greater the amount of fines and the like generated. Moreover, such fines and the like are not uniformly mixed and present in the polyester chip, but are unevenly distributed.
Therefore, the crystallization rate of a molded article made of polyester obtained by performing a contact treatment with a member made of the thermoplastic resin such as polyethylene as described below is increased, but the content of fines and the like is increased. Due to a large variation in the amount or a large variation in the amount of the thermoplastic resin adhering to the polyester surface, the variation in the crystallization speed and the transparency of the molded article become very large, which is a problem.

Therefore, the polyester treated in the water treatment step is transported to a fine and the like removal step for separating and removing fine and / or film-like materials, and before the contact treatment with the member made of the thermoplastic resin, It is desirable to remove these as much as possible.

The fine content and / or the film content of the polyester after the fine and / or film-like material has been removed by the fine and / or the like removal process installed before the contact treatment with the member made of the thermoplastic resin. Either the fine content or the total content of the film-like material content is 300 ppm or less, preferably 2 ppm or less.
It is desirable to reduce the content to 00 ppm or less, more preferably 100 ppm or less, and even more preferably 50 ppm or less.

As a method for removing fines or the like, the following method can be mentioned. That is, there may be mentioned a vibrating sieve step, an airflow classification step using an air flow, a gravity classification step, etc., which are separately provided immediately before the step of contacting with a member made of a thermoplastic resin described below.

Next, the polyester obtained in the fine or the like removing step is contact-treated with a member made of at least one resin selected from the group consisting of a polyolefin resin member, a polyamide resin member, and a polyacetal resin member. Treated in a contact treatment step.

The method of contact-treating the polyester with at least one resin member selected from the group consisting of a polyolefin resin member, a polyamide resin member, and a polyacetal resin member is performed by using the thermoplastic resin member. In the space where is present, it is preferable that the polyester is brought into collision contact with the member.Specifically, for example, immediately after the solid phase polycondensation of the polyester, during the production process such as immediately after water treatment or steam treatment, Piping for pneumatic transportation, piping for gravity transportation, silo, etc. at the time of filling into or discharging from a transportation container at the stage of transporting as a product, at the time of feeding a molding machine at the stage of polyester molding, etc. A part of the magnet portion or the like of the magnet catcher is made of the thermoplastic resin, or the thermoplastic resin is lined. Rutoka, or rod into said transfer path, and the like the melting point of the plate or mesh-like body such as installing a thermoplastic resin members of the, and a method of transferring the polyester. The contact time of the polyester with the member,
Usually, it is a short time of about 0.01 second to several minutes, but the above-mentioned polyolefin resin, polyamide resin, and polyester
Alternatively, a small amount of polyacetal resin can be blended.

The polyolefin resin used in the present invention includes a polyethylene resin, a polypropylene resin, and an α-olefin resin. These resins may be crystalline or amorphous.

The polyethylene resin used in the present invention includes, for example, a homopolymer of ethylene, ethylene and propylene, butene-1,3-methylbutene-
Other α-olefins having about 2 to 20 carbon atoms such as 1, pentene-1, 4-methylpentene-1, hexene-1, octene-1, decene-1, and the like, vinyl acetate, vinyl chloride,
Acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, copolymers with vinyl compounds such as styrene and the like can be mentioned. Specifically, for example, ethylene homopolymers such as low / medium / high density polyethylene (branched or linear), ethylene-propylene copolymer, ethylene-
Butene-1 copolymer, ethylene-4-methylpentene-
1 copolymer, ethylene-hexene-1 copolymer, ethylene-octene-1 copolymer, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, ethylene-acryl Ethylene resins such as ethyl acid copolymer are exemplified.

The polypropylene resin used in the present invention includes, for example, propylene homopolymer, propylene, ethylene, butene-1, 3-methylbutene-1, pentene-1, 4-methylpentene-1,
Carbon number 2 such as hexene-1, octene-1 and decene-1
And about 20 other α-olefins and copolymers with vinyl compounds such as vinyl acetate, vinyl chloride, acrylic acid, methacrylic acid, acrylic acid esters, methacrylic acid esters, and styrene. Specifically, for example, propylene homopolymer, propylene-ethylene copolymer,
Propylene resins such as propylene-ethylene-butene-1 copolymer are exemplified.

Examples of the α-olefin resin used in the present invention include a homopolymer of an α-olefin having about 2 to 8 carbon atoms such as 4-methylpentene-1; those α-olefins; , Butene
1,3-methylbutene-1, pentene-1, hexene-
And copolymers with other α-olefins having about 2 to 20 carbon atoms, such as 1, octene-1 and decene-1. Specifically, for example, butene-1 based resin such as butene-1 homopolymer, 4-methylpentene-1 homopolymer, butene-1-ethylene copolymer, butene-1-propylene copolymer and the like; - methylpentene-1 and C ₂ -C ₁₈ copolymer of α- olefins, and the like.

The polyamide resins used in the present invention include, for example, butyrolactam, δ-valerolactam, ε-caprolactam, enantholactam, ω
-Polymers of lactams such as laurolactam, polymers of aminocarboxylic acids such as 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, hexamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine Aliphatic diamines such as undecamethylenediamine, 2,2,4- or 2,4,4-trimethylhexamethylenediamine, 1,3- or 1,4-bis (aminomethyl) cyclohexane, bis (p-amino Alicyclic diamines such as cyclohexylmethane), diamine units such as aromatic diamines such as m- or p-xylylenediamine, and aliphatic dicarboxylic acids such as glutaric acid, adipic acid, suberic acid and sebacic acid, and cyclohexanedicarboxylic acid And other alicyclic dicarboxylic acids, terephthalic acid, isophthalic acid, etc. Polycondensates of a dicarboxylic acid units such as aromatic dicarboxylic acids, and copolymers thereof and the like can be mentioned, specifically, for example, nylon 4, nylon 6, nylon 7, nylon 8, nylon 9, nylon 1
1, nylon 12, nylon 66, nylon 69, nylon 610, nylon 611, nylon 612, nylon 6T, nylon 6I, nylon MXD6, nylon 6
/ MXD6, nylon MXD6 / MXDI, nylon 6
/ 66, nylon 6/610, nylon 6/12, nylon 6 / 6T, nylon 6I / 6T and the like. These resins may be crystalline or amorphous.

The polyacetal resin used in the present invention includes, for example, polyacetal homopolymers and copolymers. The polyacetal homopolymer has a density of 1.40 to 1.42 g / cm ^{3 as} measured by ASTM-D792, and ASTM D-12.
The melt flow ratio (MFR) measured at 190 ° C. under a load of 2160 g by the measurement method of Example No. 38 was 0.5 to 50 g / 10.
Polyacetals in the range of minutes are preferred.

The polyacetal copolymer includes:
The density measured by the method of ASTM-D792 is 1.
A polyacetal copolymer having a melt flow ratio (MFR) measured at a temperature of 190 ° C. and a load of 2160 g in a range of 0.4 to 50 g / 10 minutes by a measurement method of 38 to 1.43 g / cm ³ and ASTM D-1238 is obtained. preferable. Examples of these copolymer components include ethylene oxide and cyclic ether.

The mixing ratio of the thermoplastic resin used in the present invention to polyester is from 0.1 ppb to 0.1 ppb.
1000 ppm, preferably 0.3 ppb to 100 pp
m, more preferably 0.5 ppb to 1 ppm, even more preferably 0.5 ppb to 45 pbb. If the compounding amount is less than 0.1 ppb, the crystallization rate becomes extremely slow, and the crystallization of the plug portion of the hollow molded article becomes insufficient. The capping is poor because it does not fall within the value range, and the stretch heat-fixing mold for molding the heat-resistant hollow molded article is heavily stained, and frequent cleaning is required to obtain a transparent hollow molded article. There must be. Also 1000pp
In the case of exceeding m, the crystallization speed becomes fast, and the crystallization of the plug portion of the hollow molded article becomes excessively large, so that the shrinkage and shrinkage amount of the plug portion does not fall within the specified value range, resulting in poor capping and the content. Leakage, or whitening of the preform for a hollow molded body, making normal stretching impossible. In the case of a sheet-like material, if it exceeds 1000 ppm, the transparency becomes extremely poor, and the stretchability becomes poor, so that normal stretching is impossible, and only a stretched film having large thickness unevenness and poor transparency can be obtained. I can't.

The transport from the draining step after the water treatment to the drying step, the step of removing fines or the like, or the step of contacting with the above-mentioned thermoplastic resin, etc., is carried out in the same manner as described above, such as the plug transport method, the vortex transport method, and the bucket method. Preferably, a conveyor-transport system is employed.

The polyester according to the present invention may contain, if necessary, other additives such as a known ultraviolet absorber, an antioxidant, an oxygen absorber, an oxygen scavenger, an externally added lubricant, and an internal lubricant during the reaction. Various additives such as a deposited lubricant, release agent, nucleating agent, stabilizer, antistatic agent, dye and pigment may be blended.

The polyester obtained by the production method of the present invention is injection-molded and stretch blow-molded to form a stretched hollow molded article, and extruded to form a sheet-like material.

[0095]

EXAMPLES The present invention will be described below in more detail 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 of polyester (IV) 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) Polyethylene diethylene glyco
The content was decomposed by methanol and the amount of DEG was quantified by gas chromatography and expressed as a ratio (mol%) to the total glycol components.

(3) Polyester cyclic trimer content (hereinafter referred to as "CT content") A sample is dissolved in a hexafluoroisopropanol / chloroform mixture, and further diluted with chloroform. After adding methanol to precipitate a polymer, the mixture is filtered. The filtrate was evaporated to dryness, made up to a constant volume with dimethylformamide, and the cyclic trimer composed of ethylene terephthalate units was quantified by liquid chromatography.

(4) Acetaldehyde content of polyester (hereinafter referred to as “AA content”) Sample / distilled water = 1 g / 2 cc in a nitrogen-purged glass ampule was sealed and extracted at 160 ° C. for 2 hours. After the treatment and cooling, the acetaldehyde in the extract was measured by high-sensitivity gas chromatography, and the concentration was expressed in ppm.

(5) Increase in amount of cyclic trimer during melting of polyester (ΔCT amount) 3 g of a dried polyester chip was placed in a glass test tube, immersed in an oil bath at 290 ° C. for 60 minutes under a nitrogen atmosphere, and melted. Let it. The amount of increase of the cyclic trimer at the time of melting is determined by the following equation. Cyclic trimer increase during melting (% by weight) = Cyclic 3 after melting
Monomer content (% by weight) -cyclic trimer content before melting (% by weight)

(6) Measurement of Fine Content and Film-like Material Content About 0.5 kg of the resin is referred to as a sieve (A) with a wire mesh having a nominal size of 5.6 mm according to JIS-Z8801, and a nominal size of 1.7.
A sieve (diameter: 20 cm) (B) equipped with a 2 mm wire mesh was placed on a sieve combined in two stages, and sieved at 1800 rpm for 1 minute with a rocking sieve tow machine SNF-7 manufactured by Teraoka. This operation was repeated to sieve a total of 20 kg of the resin. In the case where two or more chips fused to each other or chips cut to a size larger than a normal shape are captured on the sieve (A) separately from the film-like material, The remaining film-like material from which the water was removed and the fines sieved under the sieve (B) were separately washed with ion-exchanged water and collected by filtration through a G1 glass filter manufactured by Iwaki Glass Co., Ltd. These are put together with a glass filter in a dryer at 100 ° C
, And then cooled and weighed. The same operation of washing and drying with ion-exchanged water was repeated again, and it was confirmed that the weight became constant. The weight of the glass filter was subtracted from this weight to obtain the fine weight and the weight of the film.
The fine or film content is the fine weight or film weight / the total resin weight sieved. The total content is determined from these values.

(7) Measurement of melting point of fine and film-like materials Differential scanning calorimeter (DS) manufactured by Seiko-Electronic Industries Co., Ltd.
C), measured using RDC-220. In (6),
Fine or film-like materials collected from 20 kg of polyester were dried under reduced pressure at 25 ° C. for 3 days, and DSC measurement was performed at a heating rate of 20 ° C./min using 4 mg of a sample for one measurement. The melting peak temperature on the highest side of the peak temperature is determined. The measurement is performed on a maximum of 10 samples, and the average value of the melting peak temperature on the highest temperature side is obtained.

(8) Average Density of Polyester Chip and Density of Preform Plug Portion The density was measured at 30 ° C. with a density gradient tube of calcium nitrate / water mixed solution.

(9) Haze (haze percentage) and haze unevenness Samples were cut out from the body (thickness of about 0.4 mm) of the molded article (5 mm thick) and the hollow molded article (13) below. Haze meter manufactured by Nippon Denshoku Co., Ltd., model NDH2
Measured at 000. In addition, a molded plate molded 10 times continuously
The haze of the sample (wall thickness: 5 mm) was measured, and the haze unevenness was determined as follows. Haze spot = maximum value of haze / minimum value of haze

(10) Density increase due to heating of preform plug portion The preform plug portion was heat-treated for 60 seconds with a homemade infrared heater, and a sample was taken from the top surface to measure the density.

(11) Unevenness of thickness of bottle Four samples (3 cm × 3 cm) were randomly cut from the center of the body of the hollow molded article of (13) described later, and the thickness was measured with a digital thickness gauge (within the same sample). Was measured at five points, and the average was taken as the sample thickness.) The thickness unevenness was determined as follows. Thickness unevenness = maximum thickness / minimum thickness

(12) Molding of Stepped Molded Plate The dried polyester was dried with M-150C (D
M) A stepped flat mold (surface temperature of about 2 ° C.) cooled by water at 10 ° C. at a cylinder temperature of 290 ° C. by an injection molding machine.
(2 ° C.). The resulting stepped plate is 2,
A plate having a thickness of about 3 cm × about 5 cm square having a thickness of 3, 4, 5, 6, 7, 8, 9, 10, 11 mm is provided in a stepwise manner, and each piece weighs about 146 g. Plates having a thickness of 5 mm are used for measuring haze (haze%).

(13) Evaluation of mold stain The polyester was dried with a dryer using dehumidified air, and a preform was molded at a resin temperature of 295 ° C. using an M-150C (DM) injection molding machine manufactured by each machine. . This preform
After heating and crystallizing the plug portion of the system with a home-made plug portion crystallizer, biaxial stretching blow molding was carried out using an LB-01E stretching blow molding machine manufactured by Co-Poplast Co., Ltd.
The resultant was heat-set in a mold set at a temperature of about 5 ° C. for about 5 seconds to obtain a 500 cc hollow molded body (the body was circular). Under the same conditions, stretch blow molding was continuously performed, and the stain on the mold was evaluated by the number of moldings until the transparency of the molded article was impaired by visual judgment. Also,
As a sample for haze measurement, a body portion of a molded body after continuous molding for 5000 times was provided.

(14) Evaluation of Leakage of Contents from Hollow Molded Article The hollow molded article molded in (13) was filled with hot water at 90 ° C., capped by a capping machine, the container was turned over, and the contents were left to stand. Was examined for leaks. The deformation of the plug after capping was also examined.

(15) Sodium Content, Calcium Content, Magnesium Content and Silicon Content of Introduced Water The introduced water from which particles have been removed and ion-exchanged has been collected and filtered through a 1G1 glass filter manufactured by Iwaki Glass Co., Ltd. Was measured with an inductively coupled plasma emission spectrometer manufactured by Shimadzu Corporation.

(16) Measurement of Number of Particles in Introduced Water and Recycled Water Particle measurement of the introduced water from which particles have been removed and ion-exchanged, or the recycled water treated in a filtration device (5) and an adsorption tower (8), by a light blocking method. Is measured using a PAC 150 manufactured by Seishin Enterprise Co., Ltd.
Displayed in ml.

(Example 1) A slurry of high-purity terephthalic acid and ethyl glycol was continuously supplied to a first esterification reactor containing a reactant in advance, and the slurry was stirred for about 2 hours.
The reaction was carried out at 50 ° 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 reacted under agitation at about 260 ° C. and 0.05 kg / cm ² G to a predetermined reactivity. In addition, crystalline germanium dioxide was dissolved in water by heating, and ethylene glycol was added thereto, and a heat-treated catalyst solution and a phosphoric acid ethylene glycol solution were separately supplied continuously to the second esterification reactor. . This esterification reaction product is continuously
Feed into the polycondensation reactor and stir at about 265 ° C, 25 to
rr for 1 hour and then about 2 hours with stirring in a second polycondensation reactor.
The polycondensation was carried out at 65 ° C. and 3 torr for 1 hour and further with stirring in a final polycondensation reactor at about 275 ° C. and 0.5 to 1 torr for 1 hour. After the melt polycondensation reaction product is formed into chips, the product is transported to a storage tank, and then fine and film-like substances are removed by a vibrating sieving step and an airflow classification step, so that the total content thereof is about 3 ppm or less, Then, it was transported to a continuous solid-state polymerization apparatus. Crystallize at about 155 ° C under a nitrogen atmosphere, and further at about 200 ° C under a nitrogen atmosphere.
After preheating, the mixture was sent to a continuous solid-state polymerization reactor and subjected to solid-state polymerization at about 205 ° C. under a nitrogen atmosphere.

A raw material chip supply port (1) at the upper part of the processing tank, an overflow discharge port (2) located at the upper limit of the processing water in the processing tank, and a discharge of a mixture of the polyester chips and the processing water at the lower part of the processing tank. The treated water discharged from the outlet (3), the overflow outlet, and the treated water discharged from the drainage device (4) for the polyester chips discharged from the outlet at the lower part of the treatment tank are used as the filter medium. A pipe (6) sent again to the water treatment tank via a fine filtration / removal device (5), which is a continuous filter, and an adsorption tower (8), a GAF filter bag PE-1P2S made by ISP (polyester felt, Introduction of water obtained by introducing new ion-exchanged water from the outside of the system into the inlet (9) in the middle of this pipe (6) via a particle remover in water and an ion exchanger with a filtration accuracy of 1 μm). With mouth (7) Tower type capacitive 50 m ^3, a polyethylene terephthalate using a processing tank shown in FIG. 1 - DOO (hereinafter,
(Abbreviated as PET) chips were continuously water-treated.

The above solid-state polymerized PET chips were processed by a vibrating sieving step and an airflow classification step to reduce the content of fines and film-like substances to about 5 ppm (the highest melting peak temperature of the fines, etc.). Peak temperature is 248 ° C
), And then continuously charged from the upper supply port (1) of the treatment tank controlled to a treatment water temperature of 95 ° C., and the discharge port (3) at the lower part of the water treatment tank after 6 hours of water treatment. To PE
Water treatment was performed while continuously extracting the T chips together with the treated water. The content of particles having a particle size of 1 to 25 μm in the introduced water collected before the ion-exchanged water introduction port (9) of the above treatment apparatus is about 1900 particles / 10 ml, and the sodium content is 0.0
1 ppm, magnesium content 0.02 ppm, calcium content 0.03 ppm, silicon content 0.07 ppm
ppm, and a filtration device (5) and an adsorption tower (8)
The particle number of the recycled water having a particle size of 1 to 40 μm after the treatment was about 18000/10 ml.

After the water treatment, the resultant was dried with heated dry air, and subsequently treated in a vibrating sieving step and an airflow classification step.
The intrinsic viscosity of the obtained PET is 0.74 deciliter / gram, the content of DEG is 2.7 mol%, the content of the cyclic trimer is 0.30% by weight, and the increase of the cyclic trimer is 0.04% by weight. %, Average density was 1.4221 g / cm ³ , AA content was 2.8 ppm, and fine content was about 8 ppm.
In addition, the residual amount of Ge measured by fluorescent X-ray analysis was 48 p.
m and the residual amount of P were 31 ppm.

The chip transport in the melt polycondensation step, the solid phase polymerization step and the water treatment, and the chip transport in the drying step are all performed by a vortex type transport system and a bucket type conveyor transport system. All of the chips were extracted from the solid-phase polymerization chip reservoir using a screw type feeder. This PET was evaluated using a molded plate and a biaxially stretched molded bottle. Table 1 shows the results.

The haze of the molded plate was 2.1%, and the density of the plug portion was 1.370 g / cm ³ , which is a value without any problem.
The continuous stretch blow molding of 0 or more pieces was carried out, but no stain on the mold was observed, and the transparency of the bottle was also good. Also, there was no problem in the leakage test of the contents, and there was no deformation of the plug portion. The body haze of the obtained bottle is 1.0%,
The haze unevenness was as good as 1.1, and the thickness unevenness was as good as 1.03.
In addition, the number of moldings up to mold contamination was 12,000, which was no problem. The AA content of the bottle was 15.5 ppm, which was a problem-free value.

(Comparative Example 1) Solid-state polymerization was carried out under exactly the same conditions as in Example 1 without treating the melt polycondensation chips obtained in the same manner as in Example 1 in the vibrating sieving step and the airflow classification step. Then, the chip after the solid phase polymerization was not treated in the fine removal step, and a water treatment was carried out under the same conditions as in Example 1 with the amount of fines and films exceeding 265 ° C. being about 410 ppm. The highest peak temperature of the melting peak temperature of this fine or the like is 285 ° C.
Met

Filter of fine filtration and removal device (5)
Clogging was very fast, and the filter had to be replaced about once every 3 to 5 hours. Note that the transportation of chips in all the steps was performed by a low-density transportation method. The intrinsic viscosity of the obtained PET is 0.74 deciliter / gram,
DEG content is 2.6 mol%, cyclic trimer content is 0.31 wt%, cyclic trimer increase is 0.05 wt%,
The average density is 1.4027 g / cm ³ and the AA content is 2.
The fine content was 5 ppm and the content was about 550 ppm.
In addition, the residual Ge amount measured by fluorescent X-ray analysis was 47 p.
m and the residual amount of P were 31 ppm. The haze of the molded plate was very high at 39.7%, which was a problem. In the leakage test of the contents, leakage of the contents was recognized. The resulting bottle had a very high haze of 17.8% and a spot haze of 1.5, which was extremely high.

[0120]

[Table 1]

[0121]

According to the present invention, there is provided a method for producing a polyester in which a polyester chip having a main repeating unit of ethylene terephthalate is treated in a treatment tank with water, wherein the fine and / or film-like material contained in the polyester is treated. The highest peak temperature of the melting peak temperature is 26.
5 ° C. or less, and water treatment is performed to maintain the fine content, the film content, or the total content of the fine content and the film content at 300 ppm or less for water treatment. A polyester can be obtained which reduces stains on piping at the time, hardly causes mold stains at the time of molding, and furthermore has good transparency and crystallization at the mouth of the bottle.

[Brief description of the drawings]

FIG. 1 is a schematic view of an example of a water treatment apparatus used in the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 Raw material chip supply port 2 Overflow discharge port 3 Polyester chip and treated water discharge port 4 Drainage device 5 Fine removal device 6 Pipe 7 Recycle water or / and ion exchange water inlet 8 Adsorption tower 9 Ion Exchange water inlet

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoshitaka Eto 20F term of 248 No. 248 Takashiro, Shiga-cho, Shiga-gun, Shiga Pref. LB05

Claims (6)

[Claims] 1. A process for producing a polyester in which a polyester chip whose main repeating unit is ethylene terephthalate is treated in a treatment tank with water, wherein a melting peak of a fine and / or film-like substance contained in the polyester is obtained. The peak temperature on the highest temperature side is 265 ° C. or less, and the content of fine content, film content, or any of the total content of fine content and film content is 300 ppm or less. A method for producing a polyester, comprising subjecting the polyester to water treatment. 2. The polyolefin resin member and the polyamide resin member after the polyester obtained by the production method according to claim 1 is subjected to a fine and / or the like removal step of removing fine and / or film-like substances as necessary. Contacting with at least one member selected from the group consisting of polyacetal resin members. 3. The polyester has a density of 1.37 g / c.
The method for producing a polyester according to claim 1, wherein m ^{3 is at} least m ³ . 4. The polyester cyclic trimer content is:
The amount is 0.50% by weight or less.
4. The method for producing a polyester according to any one of 3. 5. The polyester has an intrinsic viscosity of 0.55 to 0.55.
The method for producing a polyester according to any one of claims 1 to 4, wherein the amount is 1.30 deciliter / gram. 6. A process for removing particles having a particle size of 1 to 40 μm in the treated water, which is discharged from the treatment tank and returned to the treatment tank again, by 10,000
The method for producing a polyester according to any one of claims 1 to 5, wherein the water treatment is performed while maintaining the water content at 0 / 10ml or less.