JP2003082109A - Method for manufacturing polyester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To manufacture a polyester virtually free of foreign matters and capable of providing molds, such as a hollow mold, excellent in transparency and in flavor characteristics. SOLUTION: This polyester manufacturing method is characterized in that it contains (a) a low polymer manufacturing process wherein a terephthalic acid-containing dicarboxylic acid or its esterifiable derivative and an ethylene glycol-containing glycol or its esterifiable derivative are subjected to esterification or ester exchange, (b) a melt polycondensation process wherein the low polymer obtained in the above low polymer manufacturing process is subjected to melt polycondensation, and (c) a chipping process wherein the melt-polycondensed polyester obtained by the above melt polycondensation process is chipped while being cooled by water introduced from the outside with its chemical oxygen demand (COD) satisfying formula (1): COD<=2.5 (mg/L) for a polyester cooling time (t) satisfying formula (2): 2(sec)<=t<=180(sec).

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 in packaging materials such as bottles, films and sheets. More specifically, a polyester that contains almost no foreign matter and has excellent transparency and a molded article that does not give off-flavors or odors to its contents (good flavor), a mold for molding the molded article The present invention relates to a method for producing a polyester which is less likely to be soiled and a polyester which is less likely to be clogged with a filter during film formation and spinning and has improved operability.

[0002]

BACKGROUND OF THE INVENTION Polyester such as polyethylene terephthalate has a high industrial value because of its excellent mechanical properties and chemical properties, and it has high industrial value.
Widely used as bottles.

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 thereof. Among these, 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, carbonated drink and the like.

Such a 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 having a predetermined shape and stretch blow-molded, followed by a body portion of a bottle. Heat treatment (heat set)
It is then generally molded into a hollow molded container, and if necessary, the bottle cap is heat treated (crystallized in the cap).

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. Dirt was easy 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 material of the container or other packaging molded from this is also high, which affects the flavor and odor of the beverage or the like filled in the container or the like. Therefore, various measures have been conventionally taken to reduce the acetaldehyde content in polyester.

In recent years, polyester containers centered on polyethylene terephthalate have been used for mineral water and water.
It has come to be used as a container for low flavor beverages such as ron tea. In the case of such a beverage, these beverages are generally heat-filled or sterilized by heating after filling, but the flavor and odor of these contents may not be improved only by reducing the acetaldehyde content of the beverage container. I understand.

For the metal can for beverages, a metal plate coated with a polyester film having ethylene terephthalate as a main repeating unit on its inner surface is used for the purpose of process simplification, hygiene and pollution prevention. The method of making cans has come to be adopted. Also in this case, the contents are heat-sterilized at a high temperature after filling, but it has been found that the flavor and odor of the contents are not improved by using a film having a low acetaldehyde content.

The melt polycondensed polyester is extruded from the pores after the completion of the melt polycondensation and is made into chips while being cooled with cooling water. Since it is disadvantageous in terms of cost to use distilled water as cooling water in the chip forming step, it is common to use industrial water that is a simple treatment of water from rivers, groundwater, drainage, and the like. However, when the cooling treatment using industrial water, there is often a problem that the flavor and aroma of the content of the obtained molded container becomes very bad,
This solution was awaited. In such a case, crystallization of the obtained polyester at the time of molding is too early, resulting in a bottle with poor transparency, and shrinkage of the plug part due to crystallization of the plug part does not fall within the specifications. There was also the problem of capping failure.

According to the study of the present inventors, this is an organic compound originating from bacteria, bacteria and the like contained in industrial water, spoiled plants and animals, or industrially used at the stage of chip formation. It was found that the organic compounds and the like adhered to and penetrated the polyester chips at the time of chip formation, and these caused the residual off-taste and off-odor of the molded product.

Further, the organic compound and the metal-containing substance attached to the surface of the chip and brought into the solid-state polymerization reaction device in the chip-forming step, together with a part of the surface layer of the polyester chip, are contained in the wall of the solid-state polymerization device. It sticks to, and this is about 17
When heated at a high temperature of 0 ° C or higher for a long time, it becomes a scale and adheres to the vessel wall. Then, it sometimes peels off and mixes into the polyester chip, and becomes a foreign substance in a molded article such as a bottle, which may reduce the commercial value.

[0012]

DISCLOSURE OF THE INVENTION The present invention is to solve the problems of the prior art, contains almost no foreign matter,
The present invention relates to a method for producing a polyester, which is capable of giving a hollow molded article having excellent transparency and flavor, and which is less likely to cause mold stains during molding of the molded article.

[0013]

In order to achieve the above object, a method for producing a polyester of the present invention comprises a dicarboxylic acid containing terephthalic acid or an ester-forming derivative thereof and a glycol containing ethylene glycol or an ester thereof. A low-polymer production step (a) of esterifying or transesterifying with a forming derivative, a melt polycondensation step (b) of melt-polycondensing the low-polymer obtained in the low-polymer production step, and the melt. To the melt polycondensed polyester obtained in the polycondensation step, introduced water having a chemical oxygen demand (COD) satisfying the following (1) was introduced from outside the system, and the cooling time (t) of the polyester was A method for producing polyester, comprising a chipping step (c) of chipping while cooling with cooling water so as to satisfy 2). COD ≤ 2.5 (mg / l) (1) 2 (sec) ≤ t ≤ 180 (sec) (2)

In this case, the surface temperature S of the molten polycondensed polyester which is cooled with the cooling water in the chipping step (c) being 7 to 50 ° C. and the cooling water amount V (cm ³ / sec). Chips can be formed under the condition that the ratio (V / S) of (cm ² / sec) satisfies the following (3). 0.1 ≤ (V / S) ≤ 2.0 (3) In this case, the melt polycondensed polyester having an intrinsic viscosity of 0.30 to 0.80 deciliter / gram obtained in the chipping step is solid phased. A solid phase polymerization step (d) of polymerizing can be added.

In this case, the water content adhering to the melt polycondensed polyester chips sent from the chip forming step (c) to the solid phase polymerization step may be 3000 ppm or less.

In this case, a fine removal step (h) for removing fines and / or film-like substances can be added after the chip forming step (c).

In this case, an intermediate step (e) between the chip forming step (c) and the solid phase polymerization step (d), or the solid phase polymerization step (d) and the solid phase polymerization step (d). The removal step (h) for removing fines and / or film-like substances may be added to at least one intermediate step of the intermediate step (g) and the subsequent step (f) installed after the step (b). it can.

In this case, the fine content of the melt polycondensed polyester supplied in the solid phase polymerization step (d),
Content of at least one of the film content, or the total content of the fine content and the film content, or the fine content of the solid-phase polymerized polyester supplied in the subsequent step (f), the film Content, or at least one of the total content of the fine content and the film content, is 5
It can be up to 00 ppm.

Here, fine means JIS-Z8801.
According to JIS means fine powder of polyester that has passed through a sieve having a mesh size of 1.7 mm, and a film-like material remains on a sieve having a mesh size of 5.6 mm according to JIS-Z8801. Of polyester, it means a film-like material after two or more chips are fused or the chip-like material cut into pieces larger than the normal shape is removed, and the content thereof is measured by the following measuring method. .

In this case, the subsequent step (f)
Can be at least one of a contact treatment step with water and a thermoplastic resin blending step.

In this case, in at least one of the melt polycondensation step (b), the chip forming step (c), the solid phase polymerization step (d), the post-step (f), and the fines removing step (h). As the gas that comes into contact with the polyester, it is possible to use a gas introduced from outside the system, in which the number of particles having a particle size of 0.3 to 5 μm is 1,000,000 particles / cubic foot or less.

In this case, the polyester obtained by injection molding has an intrinsic viscosity of 0.60 to 2.00 deciliter / gram, an acetaldehyde content of 10 ppm or less, and a cyclic trimer content of 0.5% by weight or less. The number of spherulites generated when the formed molded plate is crystallized at elevated temperature is 1 × 10 ⁹ to 1
It may be a solid-state polymerized polyester in the range of 5 × 10 ⁹ pieces / m ² .

[0023]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the method for producing a polyester of the present invention will be specifically described below. The polyester according to the present invention is a polyester whose main repeating unit is ethylene terephthalate, preferably a linear polyester containing 80 mol% or more of ethylene terephthalate units, more preferably 85 mol% or more, and particularly preferably 90 mol%. % Linear polyester.

As the dicarboxylic acid as a copolymerization component used when the polyester is a copolymer,
Aromatic dicarboxylic acids such as isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, diphenoxyethanedicarboxylic acid and their functional derivatives, 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 acid and other alicyclic dicarboxylic acids and their functional compounds Examples thereof include derivatives.

As the glycol used as a copolymerization component when the polyester is a copolymer, diethylene glycol, trimethylene glycol, tetramethylene glycol, neopentyl glycol, etc. may be used. Aliphatic glycols, alicyclic glycols such as cyclohexane dimethanol, polyalkylene glycols such as polyethylene glycol and polybutylene glycol, and bisphenols.
And aromatic glycols such as alkylene oxide adducts of bisphenol A and bisphenol A.

Further, as the polyfunctional compound as a copolymerization component used when the polyester is a copolymer, examples of the acid component include trimellitic acid and pyromellitic acid. Examples of the component include glycerin and pentaerythritol. The amount of the above copolymerization component used should 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 method for producing a polyester of the present invention is a direct esterification in which terephthalic acid, ethylene glycol and, if necessary, other copolymerization components are directly reacted to distill off water to esterify, and then polycondensate under reduced pressure. Law, or
Melt polycondensation polyester prepared by reacting dimethyl terephthalate with ethylene glycol and optionally other copolymerization components to distill off methyl alcohol for transesterification and then polycondensation under reduced pressure. Is a method of manufacturing. Further, it is a method for producing a polyester in which solid phase polymerization is carried out in order to increase the intrinsic viscosity and reduce the acetaldehyde content and the like, if necessary. In order to accelerate crystallization before solid-phase polymerization, the molten polycondensed polyester may be adsorbed with moisture and then crystallized by heating, or steam may be directly blown onto the polyester chips to be crystallized by heating.

The low polymer production step (a) and the melt polycondensation step (b) may be constituted by a batch reactor or a continuous reactor. In any of these methods, the esterification or transesterification reaction and the melt polycondensation reaction are
It may be performed in stages, or may be divided into multiple stages. The solid phase polymerization step (d) may be composed of a batch reaction apparatus or a continuous reaction apparatus, like the above-mentioned steps. The low polymer production step (a), the melt polycondensation step (b) and the solid phase polymerization step (d) may be operated continuously or separately. Generally, the low polymer production step (a) and the melt polycondensation step (b) are connected and operated.

An example of a preferable continuous production method will be described below using polyethylene terephthalate as an example. The raw material containing the above-mentioned terephthalic acid or its ester-forming derivative and ethylene glycol or its ester-forming derivative is esterified or transesterified in the low polymer production step (a) to become a low polymer. .

When the low-condensation product is produced by the esterification reaction, 1.02 to 1.5 mol, preferably 1.03, relative to 1 mol of terephthalic acid or its ester derivative.
~ 1.4 mol slurry containing ethylene glycol
Is continuously supplied to the esterification reaction step.

Such an esterification reaction may be carried out in one step or in multiple steps. A case of performing the operation in multiple stages will be described. In the esterification reaction, water or alcohol produced by the reaction is used in a rectification column under a condition in which ethylene glycol is refluxed using a multistage apparatus in which at least two esterification reactors are connected in series. Perform while removing to the outside. The temperature of the first stage esterification reaction is 240 to 270 ° C, preferably 245 to 265 ° C,
The pressure is 0.02 to 3 kg / cm ² G, preferably 0.0
It is 5 to ² kg / cm ² G. The temperature of the final stage esterification reaction is usually 250 to 280 ° C, preferably 255 to 280 ° C.
275 ° C, pressure is usually 0-1.5 kg / cm
² G, preferably 0 to 1.3 kg / cm ² G. When it is carried out in three or more stages, the reaction conditions for the esterification reaction in the intermediate stage are those between the reaction conditions of the first stage and the reaction conditions of the final stage. The increase in the reaction rate of these esterification reactions is preferably distributed smoothly at each stage. Finally, it is desirable that the esterification reaction rate reaches 90% or more, preferably 93% or more. A low polycondensate having a molecular weight of about 500 to 5000 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 it may be carried out in the presence of a polycondensation catalyst.

Further, tertiary amines such as triethylamine, tri-n-butylamine and benzyldimethylamine, tetraethylammonium hydroxide, tetra-hydroxide.
When quaternary ammonium hydroxide such as n-butylammonium or trimethylbenzylammonium hydroxide and a basic compound such as lithium carbonate, sodium carbonate, potassium carbonate or sodium acetate are added in a small amount, the main component of polyethylene terephthalate is obtained. It is preferable because the ratio of the dioxyethylene terephthalate component unit in the chain can be maintained at a relatively low level (5 mol% or less based on the total diol component).

When the low polycondensate is produced by the transesterification reaction, 1.1 to 1.6 mol, preferably 1.2 to 1.5 mol of ethylene glycol is used with respect to 1 mol of dimethyl terephthalate. A solution containing benzene is prepared and continuously supplied to the transesterification reaction step.

In the transesterification reaction, the methanol produced by the reaction is subjected to rectification in a rectification column under the condition that ethylene glycol is distilled off using a device in which 1 to 2 transesterification reactors are connected in series. Perform it while removing it 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 stage transesterification reaction is usually 230 to 270 ° C., preferably 24.
0 to 265 ° C., Zn as an ester exchange catalyst,
Fatty acid salts such as Cd, Mg, Mn, Co, Ca and Ba,
Carbonate, Pb, Zn, Sb, Ge oxide or the like is used. Due to these transesterification reactions, the molecular weight is about 200-500.
A low polymer is obtained.

As the starting material dimethyl terephthalate, terephthalic acid or ethylene glycol, virgin dimethyl terephthalate derived from paraxylene, ethylene glycol derived from terephthalic acid or ethylene, and used PE are used.
A recovered raw material such as dimethyl terephthalate, terephthalic acid, bishydroxyethyl terephthalate or ethylene glycol recovered from a T bottle by a chemical recycling method such as methanol decomposition or ethylene glycol decomposition can also be used as at least a part of the starting material. It goes without saying that the quality of the recovered raw material must be refined to the purity and quality according to the purpose of use.

Next, the low polymer thus obtained is heated under reduced pressure in the presence of a polycondensation catalyst to a temperature not lower than the melting point of the polyester obtained, and the glycol produced at this time is distilled out of the system. It is supplied to the melt polycondensation step (b) for polycondensation.

The polycondensation reaction in the melt polycondensation step (b) may be carried out in one stage or in multiple stages. A case of performing the operation in multiple stages will be described. The polycondensation reaction condition is that the reaction temperature of the first stage polycondensation is 250 to 290.
℃, preferably 260-280 ℃, the pressure is 500
~ 20 Torr, preferably 200-30 Torr,
The temperature of the polycondensation reaction in the final stage is 265 to 300 ° C, preferably 275 to 295 ° C, and the pressure is 10 to 0.1T.
orr, preferably 5 to 0.5 Torr. When the polycondensation reaction is carried out in three or more steps, the reaction conditions for the intermediate polycondensation reaction are those between the reaction conditions of the first stage and the reaction conditions of the final stage. The degree of increase in intrinsic viscosity reached in each of these polycondensation reaction steps is preferably distributed smoothly.

The polycondensation reaction is carried out using a polycondensation catalyst.
As the polycondensation catalyst, a compound of Ge, Sb, Ti, or Al is used, and Ge compound and Ti compound, Ge
It is also convenient to use mixed catalysts of compounds and Al compounds, Sb and Ti compounds, Sb and Ge compounds. These compounds are added to the reaction system as powders, aqueous solutions, ethylene glycol solutions, ethylene glycol slurries, and the like.

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, or ethylene glycol added thereto and heat treated A solution obtained by heating and dissolving germanium dioxide in water or an ethylene glycol-containing solution is used to obtain the polyester used in the present invention.
It is preferable to use a solution which has been heated by adding a solvent. These polycondensation catalysts can be added during the esterification process. When a Ge compound is used, the amount used is 10 to 150 ppm, preferably 13 to 100 ppm, and more preferably 15 to 70 p, as the Ge residual amount in the produced polymer.
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 their partial hydrolysis. Examples thereof include titanyl oxalate, titanyl ammonium oxalate, sodium titanyl oxalate, potassium titanyl oxalate, titanyl calcium oxalate, titanyl oxalate compounds such as strontium titanyl oxalate, trimellitic acid titanium, titanium sulfate, titanium chloride and the like. The Ti compound is a formed polymer.
It is added so that the remaining amount of Ti in it is in the range of 0.1 to 10 ppm.

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

As the Al compound, specifically,
Aluminum formate, aluminum acetate, basic aluminum acetate, aluminum propionate, aluminum oxalate, aluminum acrylate, aluminum laurate, aluminum stearate, aluminum benzoate, aluminum trichloroacetate, aluminum lactate,
Carboxylates such as aluminum citrate and aluminum salicylate, aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride, polyaluminum chloride,
Inorganic acid salts such as aluminum nitrate, aluminum sulfate, aluminum carbonate, aluminum phosphate, aluminum phosphonate, aluminum methoxide, aluminum ethoxide, aluminum n-propoxide, aluminum iso-propoxide, aluminum n-butoxide, aluminum t-butoxide, etc. Aluminum chelate compounds such as aluminum alkoxide, aluminum acetylacetonate, aluminum acetylacetate, aluminum ethylacetoacetate, aluminum ethylacetoacetate diiso-propoxide, trimethylaluminum, triethylaluminum and other organoaluminum compounds and their partial hydrolysates. , Aluminum oxide and the like. Among these, carboxylates, inorganic acid salts and chelate compounds are preferable, and among these, basic aluminum acetate, aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride and aluminum acetylacetonate are particularly preferable. The Al compound is added so that the amount of Al remaining in the produced polymer is in the range of 5 to 200 ppm.

In the method for producing polyester of the present invention, an alkali metal compound or an alkaline earth metal compound may be used in combination. Examples of alkali metals and alkaline earth metals include Li, Na, K, Rb, Cs, Be and M.
At least one selected from g, Ca, Sr, and Ba is preferable, and the use of an alkali metal or a compound thereof is more preferable. When using an alkali metal or a compound thereof, use of Li, Na and K is particularly preferable.
Examples of the alkali metal or alkaline earth metal compound include, for example, formic acid, acetic acid, propionic acid, butyric acid of these metals,
Saturated aliphatic carboxylates such as oxalic acid, unsaturated aliphatic carboxylates such as acrylic acid and methacrylic acid, aromatic carboxylates such as benzoic acid, halogen-containing carboxylates such as trichloroacetic acid, lactic acid, citric acid, Hydroxycarboxylic acid salts such as salicylic acid, carbonic acid, sulfuric acid, nitric acid, phosphoric acid, phosphonic acid, hydrogen carbonate, hydrogen phosphate, hydrogen sulfide, sulfurous acid, thiosulfuric acid, hydrochloric acid, hydrobromic acid, chloric acid, bromic acid, etc. Acid salts, organic sulfonates such as 1-propanesulfonic acid, 1-pentanesulfonic acid and naphthalenesulfonic acid, organic sulfates such as laurylsulfate, methoxy, ethoxy, n-propoxy, iso-propoxy, n-butoxy, tert. -Alkoxides such as butoxy, chelate compounds with acetylacetonate, hydrides,
Examples thereof include oxides and hydroxides. The above-mentioned alkali metal compound or alkaline earth metal compound is added to the reaction system as a powder, an aqueous solution, an ethylene glycol solution or the like. Alkali metal compounds or alkaline earth metal compounds are used as the residual amount of these elements in the produced polymer in the range of 1 to
Add so that it is in the range of 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 their derivatives. Specific examples include phosphoric acid, phosphoric acid trimethyl ester, phosphoric acid triethyl ester, phosphoric acid tributyl ester, phosphoric acid triphenyl ester, phosphoric acid monomethyl ester, phosphoric acid dimethyl ester, phosphoric acid monobutyl ester, phosphoric acid dibutyl ester, Phosphoric acid, trimethyl phosphite, triethyl phosphite, tributyl phosphite, methylphosphonic acid,
Methylphosphonic acid dimethyl ester, ethylphosphonic acid dimethyl ester, phenylphosphonic acid dimethyl ester, phenylphosphonic acid diethyl ester, phenylphosphonic acid diphenyl ester, and the like, which may be used alone or in combination of two or more. You may use together. The P compound is 1 to 1 as the residual amount of P in the produced polymer.
It can be added at any stage of the above-mentioned polyester formation reaction step so that it is in the range of 1000 ppm.

The molten polyester obtained from the final polycondensation reactor is then sent to the chip forming step (c). In the chipping step (c), the melt polycondensed polyester is extruded into the water through the pores of the die and cut in water, or is extruded into the air and immediately cut while cooling with cooling water. Chiped. The water adhering to the chip surface is removed by an air flow or the like, and is dried by hot air or the like as necessary. The cooling water discharged from the chip forming step (c) alone or together with the chips is sent to a cooling water storage tank or the like for reuse, and mixed with the introduced water introduced from outside the system in this tank, After adjusting the temperature to a certain temperature, it is used as cooling water for chips.

Here, the melt polycondensation step (b) means a step from the end of the low polymer production step (a) to the discharge from the final melt polycondensation reactor through a die. The melt polycondensed polyester obtained as described above is extruded from the pores after completion of the melt polycondensation, and is made into chips while being cooled with cooling water. Since using distilled water as cooling water in the chip formation step (c) is disadvantageous in terms of cost, it is common to use industrial water (natural water) obtained by simply treating water from rivers, groundwater, drainage, etc. Target. Usually, this industrial water is taken from river water, groundwater, etc., and is said to have been subjected to treatment such as sterilization and removal of foreign substances without changing the shape of water (liquid). In addition, natural water that is generally used for industrial purposes is derived from natural sources such as inorganic particles such as silicates, aluminosilicates and other clay minerals, bacteria, bacteria, and spoiled plants and animals. It contains a large amount of organic compounds having, or industrially used organic compounds. It has been found that such an organic compound often adheres to the surface of the chip and penetrates into the chip to affect the flavor property of the content of the molded body.

In the polyester production method of the present invention, the chemical oxygen demand (C
By introducing introduced water whose OD) satisfies the following (1) from the outside of the system and making the melt polycondensed polyester into chips so that the cooling time (t) of the polyester satisfies the following (2) It solves the above problems. COD ≤ 2.5 (mg / l) (1) 2 (sec) ≤ t ≤ 180 (sec) (2)

The COD of fresh water introduced into the chip forming step (c) is 0.1 to 2.5 mg / l, preferably 0.1 to 2.5 mg / l.
2.0 mg / l, more preferably 0.1-1.0 mg / l
It is l.

When the COD of the fresh water introduced in the chip forming step (c) is less than 0.1 mg / l, the equipment cost becomes high and economical chip formation may not be possible. In addition, C of fresh water to be introduced in the chip forming step (c)
If the OD exceeds 2.5 mg / l, the flavor of the contents of the molded product may deteriorate, which is a problem. The method of reducing the COD of fresh water introduced into the chip forming step (c) is illustrated below, but the present invention is not limited to this.

In order to reduce the COD of the fresh water introduced into the chipping step (c), at least the step until industrial water is sent to the chipping step (c) for feeding to the chipping step (c). Install a device to reduce the COD of water at one or more places. Further, a device for reducing COD may be installed at least at one or more locations in the process until the water discharged from the chipping step (c) is returned to the chipping step (c) again. Examples of a device for reducing COD include a device that performs microfiltration, coagulation and sedimentation, and activated carbon treatment.

In the polyester production method of the present invention, the cooling time (t) of the molten polycondensed polyester with cooling water in the chipping step (c) is 2 to 180 se.
c, preferably 3 to 150 sec. When the cooling time (t) is less than 2 sec, the molten polycondensed polyester is insufficiently cooled, and the chips are fused to each other to give chips having a normal shape. If it exceeds 180 seconds,
Flavor becomes worse. Here, for the cooling time (t) of the melt polycondensed polyester, the melt polycondensed polyester is extruded from the pores of the die and comes into contact with cooling water, is made into chips while being cooled, and then leaves the device for removing the adhered water. It's time to go.

In the method for producing polyester of the present invention, the sodium content, magnesium content, silicon content and calcium content in the introduced water introduced into the chipping step (c) are respectively N, M, and calcium. When S and C are used, it is desirable that the melt polycondensed polyester be chipped so as to satisfy at least one of the following (4) to (7). N ≤ 1.0 (ppm) (4) M ≤ 0.5 (ppm) (5) S ≤ 2.0 (ppm) (6) C ≤ 1.0 (ppm) (7)

The sodium content (N) in the introduced water is preferably N ≦ 0.5 ppm, more preferably N
≦ 0.1 ppm. The magnesium content (M) in the introduced water is preferably M ≦ 0.3 ppm, more preferably M ≦ 0.1 ppm. The content (S) of silicon in the introduced water is preferably S ≦ 0.5 ppm, more preferably S ≦ 0.3 ppm. Further, the calcium content (C) in the introduced water is preferably C ≦ 0.5 ppm, more preferably C ≦ 0.1.
It is ppm.

Further, the lower limits of the sodium content (N), magnesium content (M), silicon content (S) and calcium content (C) in the introduced water are N ≧
0.001ppm, M ≧ 0.001ppm, S ≧ 0.0
2 ppm and C ≧ 0.001 ppm. In order to make it below such a lower limit value, enormous capital investment is required, and the operating cost becomes very high, so that economical production is difficult.

Introduced water whose sodium content (N), magnesium content (M), silicon content (S) and calcium content (C) satisfy the above (4) to (7). The molded product from melt-polycondensed polyester that is made into chips while cooling by using, or a polyester obtained by solid-phase polymerization of this is very excellent in transparency, and the filter during spinning is less likely to be clogged and the operability is very high. To be stable. When using introduced water that deviates from the above conditions, these metal-containing compounds adhere to the polyester chip surface, the crystallization rate of the final polyester obtained is very fast, and its fluctuation becomes large, Moreover, only polyester containing foreign substances containing these metals can be obtained, which is not preferable.

The method for suppressing the sodium content, magnesium content, silicon content, and calcium content of the introduced water within the above ranges will be illustrated below, but the present invention is not limited thereto.

Chiping step (c) to reduce sodium, magnesium, calcium, and silicon in the introduced water.
An apparatus for removing sodium, magnesium, calcium, and silicon is installed at at least one place in the process until industrial water is sent to. A filter is installed to remove clay minerals such as particulate silicon dioxide and aluminosilicate. Examples of the device for removing sodium, magnesium, calcium, and silicon include an ion exchange device, an ultrafiltration device, and a reverse osmosis membrane device. Further, the particle size present in the introduced water introduced from outside the system is 1 to
It is desirable to use water in which particles of 25 μm are not more than 50,000 / 10 ml. Particle size of introduced water 1-25μ
The number of m particles is preferably 10,000 particles / 10 ml
The number is preferably 1000 pieces / 10 ml or less, more preferably 100 pieces / 10 ml or less.

The lower limit value of particles having a particle size of 1 to 25 μm is 1 particle / 10 ml or more, and enormous equipment investment is required to make the particle size lower than the lower limit value, and the operating cost becomes very high. Economical production is difficult.

Particles having a particle size of more than 25 μm in the introduced water are
Although not particularly specified, preferably 2000 /
It is 10 ml or less, more preferably 500 pieces / 10 ml or less, further preferably 100 pieces / 10 ml, and particularly preferably 10 pieces / 10 ml or less.

The particles having a particle size of less than 1 μm in the introduced water are not particularly specified in the present invention, but in order to obtain a transparent molded product or a polyester giving a molded product having an appropriate crystallization rate. The smaller the number, the better. Particle size 1
The number of particles less than μm is preferably 100,000 /
10 ml or less, more preferably 50,000 pieces / 10 ml
Or less, more preferably 20,000 pieces / 10 ml or less,
Particularly preferably, it is 10,000 pieces / 10 ml or less. 1
As a method for removing and controlling particles having a size of μm or less from water, a microfiltration method or an ultrafiltration method using a membrane such as a ceramic membrane or an organic membrane can be used.

Below, 50000 particles with a particle size of 1 to 25 μm were introduced in the introduced water introduced in the chip forming step (c).
A method of controlling the amount to be less than or equal to ml is illustrated, but the present invention is not limited to this.

As a method for reducing the number of particles in water to 50,000 particles / 10 ml or less, an apparatus for removing particles is installed at at least one place until natural water such as industrial water is supplied to the chip forming step (c). . Preferably, a device for removing particles is installed between the natural water collecting port and the chipping step, and the particles having a particle size of 1 to 25 μm in the water supplied to the chipping step (c) are Content 500
It is preferable that the number is 100 pieces / 10 ml or less. As a device for removing particles, a filter filtration device, a membrane filtration device,
A precipitation tank, a centrifuge, a foam entrainment processing machine, etc. are mentioned.
For example, in the case of a filter filtration device, examples thereof include a belt filter system, a bag filter system, a cartridge filter system, a centrifugal filtration system and the like. Among them, a belt filter type, a centrifugal filtration type, and a bag filter type filtration device are suitable for continuous operation. Further, in the case of a belt filter type filtering device, examples of the filter material include paper, metal, cloth and the like. The size of the mesh of the filter is 5 to 100 μm, preferably 10 to 70 μm in order to efficiently remove particles and efficiently introduce water.
m, and more preferably 15 to 40 μm.

Further, in the method for producing polyester of the present invention, the water temperature of the cooling water in the chipping step (c) is 7
Surface area S (cm ² ) of the melt-polycondensed polyester cooled at a temperature of -50 ° C. and a cooling water amount V (cm ³ / sec).
/ Sec) (V / S) is preferably chipped under the condition that the following (3) is satisfied. 0.1 ≤ (V / S) ≤ 2.0 (3) Here, the surface area S of the melt-polycondensed polyester to be cooled
(Cm ² / sec) is the surface area of the polyester per unit time which is cooled by contact with cooling water before being cut into chips.

The temperature of the cooling water is preferably 10 to 10.
The temperature is 40 ° C, more preferably 13 to 30 ° C.
In order to maintain the temperature of the cooling water below 7 ° C., very expensive equipment is required, and the energy cost becomes high, so it is not practical from the economical viewpoint. If the chipping equipment is of the type that cuts polyester strands,
If the temperature of the cooling water is lower than 7 ° C, the surface layer of the strand becomes too hard and the shape of the cut surface becomes poor, so that fines are often generated during cutting. In the case of subsequent solid-phase polymerization, when such a chip is transported to the solid-state polymerization step, the crystallinity may be increased due to the impact force and shearing force acting on the cut surface in the transportation step and the solid-state polymerization step as described later. This is not preferable because it has a accelerating effect and often produces fines which also affects the transparency of the molded product, and a structure which exerts the same effect on the chip cutting surface is also generated. Further, also in the case of so-called underwater cutting equipment in which a melt polycondensed polyester melt is extruded into water from a die and cooled to be made into chips, the shape of the cut surface and the shape of the chips are similarly defective. On the other hand, when the temperature of the cooling water exceeds 50 ° C., the polyester is insufficiently cooled, resulting in defective chips or lumps in which 2 to several chips are fused, which is a problem.

On the other hand, when the ratio (V / S) of the amount of cooling water to the surface area of the melt polycondensed polyester is less than the above lower limit value, the melt polycondensed polyester is insufficiently cooled and the shape A defective chip or a lump of two to several chips fused together becomes a problem. In addition, the ratio (V
When / S) exceeds the above upper limit value, energy cost becomes high and it is not practical in terms of economy.

In the water discharged from the chip forming step (c), abnormal shape products such as fine polyester powder (hereinafter sometimes referred to as "fine") and fine particles generated during chip formation are mixed. However, during long-term production, the content of these in water increases, and the pipes and the chipping device become heavily soiled, resulting in clogging of the pipes. Therefore, it is possible to install a fine removal device such as a filter filtration device or a centrifuge at at least one place during the process until the water discharged from the chip forming step (c) returns to the cooling water storage tank or the like. .

The shape of the polyester chips according to the present invention may be any of cylinder type, square type, spherical type or flat plate type, and the average particle size thereof is usually 1.5 to 5 mm, preferably 1. 6 to 4.5 mm, more preferably 1.8
The range is up to 4.0 mm. 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. In the case of spherical particles, it is practical that the maximum particle size is 1.1 to 2.0 times the average particle size and the minimum particle size is 0.7 times or more the average particle size. Also,
It is practical that the weight of the chip is in the range of 10 to 30 mg / piece.

The intrinsic viscosity of the melt-polymerized polyester according to the present invention is 0.55 to 1.30 deciliter / gram, preferably 0.58 to 1.20 deciliter / gram, more preferably 0.60 to 0.90 deciliter. / Gram range. When the intrinsic viscosity is less than 0.55 deciliter / gram, the mechanical properties of the obtained molded product and the like are poor.
If it exceeds 1.30 deciliters / gram,
When the resin is melted by a molding machine or the like, the temperature of the resin becomes high and the thermal decomposition becomes severe, which causes problems such as an increase in free low molecular weight compounds that affect the fragrance retaining property, and a molded product being colored yellow.

In the case of solid-state polymerization subsequent to melt polycondensation, the intrinsic viscosity of the polyester obtained from the final polycondensation reactor for melt polycondensation is 0.30 to 0.80 deciliter / gram, preferably 0.1. It is preferably in the range of 35 to 0.75 deciliter / gram, more preferably 0.40 to 0.70 deciliter / gram. If the intrinsic viscosity is less than 0.30, the degree of crystallinity becomes too high in the pre-crystallization before the solid phase polymerization, which slows down the solid phase polymerization rate, making economical production impossible. Also, due to the brittleness of the chips, a large amount of fine polyester is generated in the pre-crystallization and solid-state polymerization steps as will be described later, and the crystallization rate is very fast, and the rate fluctuation is very large. I can't. Further, when the intrinsic viscosity exceeds 0.80, the acetaldehyde content of the solid-phase polymerized polyester obtained from such melt polycondensed polyester cannot be reduced to 10 ppm or less. Therefore, the flavor and odor of the content of the molded product obtained from such solid-phase polymerized polyester are adversely affected. In addition, the hue also becomes very yellow, which reduces the commercial value of the obtained molded product.

Further, in the method for producing polyester of the present invention, the water content attached to the melt polycondensed polyester chips sent from the chip forming step (c) to the solid-state polymerization step is 300.
It should be 0 ppm or less, preferably 2500 ppm or less, and more preferably 2000 ppm or less. If the adhered water content exceeds 3000 ppm, the flavor and aroma of the contents in the hollow molded article or the like using such polyester chips will be extremely deteriorated.

Here, the chipping step (c) means a stage from the exit of the die after the final melt polycondensation reactor to the separation of the chips after chipping from the cooling water.

The polyester melt-polycondensed as described above is chipped and then transported through the transportation pipe to a storage silo or a solid phase polymerization step (d). When such chips are transported by, for example, a forced low-density transportation method using air, a large impact force is applied to the surface of the molten polycondensed polyester chips due to the collision with the pipe, and as a result, fine or film is produced. A large amount of particles are generated. Such a fine or film-like substance has an effect of promoting crystallization of polyester, and when it is present in a large amount, the transparency of the obtained molded product becomes very poor. Further, such fines and film-like substances include those having a melting point higher by about 10 to 20 ° C. than the normal melting point.
Further, when a melt polycondensed polyester chip is used with a feeder that is subjected to impact force or shear force, a very large amount of fines or film-like substances having a melting point higher than the normal melting point by about 10 to 20 ° C. or more are generated. . It is presumed that this is because the chip heats up due to a large force such as an impact force applied to the chip surface, and at the same time, oriented crystallization of polyester occurs on the chip surface, resulting in a dense crystal structure.

About 10 to 20 above the normal melting point
When melt-polycondensed polyester fine or film-like material having a melting point higher than ℃ is subjected to solid-state polymerization treatment together with melt-polycondensed polyester chips, and subsequently subjected to treatment such as contact treatment with water described below, these melting points are treated. It will be even higher than before. Even fine or film-like materials having a melting point not higher than the normal melting point by about 10 ° C. or higher, the melting point of the fine or film-like material is about 1% higher than the normal melting point.
It has a high melting point of 0 to 20 ° C or more. It is presumed that this is because the crystal structure is changed to a more dense crystal structure by these treatments.

Generally, the melt polycondensation polyester is about 10 to 2 above the normal melting point, depending on the production method.
It contains about 50 ppm to several wt% of fines having a high melting point of 0 ° C. or higher, and fines containing a part of film, and such fines are present in the melt polycondensed polyester chips in a uniform mixed state. Not ubiquitous but unevenly distributed. Therefore, if such a melt polycondensed polyester is molded into a molded product as it is, only a molded product having poor transparency is obtained, which is a problem. In addition, if the solid phase polymerization is performed as it is, or if the subsequent contact treatment with water is performed, the crystallization rate is further increased,
Further, only polyester having a very fluctuating speed can be obtained, which is a problem.

Therefore, in the method for producing polyester of the present invention, it is desirable to add a fine etc. removing step (h) for removing fines and / or film-like substances after the chip forming step (c).

The fine content of the melt-polycondensed polyester obtained by the method for producing polyester of the present invention is 5
The above problems can be solved by adjusting the amount to 000 ppm or less, preferably 3000 ppm or less, more preferably 1000 ppm or less, and further preferably 5 ppm or less.
It is desirable to reduce it to 00 ppm or less, most preferably 100 ppm or less.

As a method for removing fines and the like from the melt polycondensed polyester, a vibrating sieving process installed after the above chipping process (c), an air flow classification process by an air flow,
Alternatively, a method of treating the melt polycondensed polyester in a gravity type classification step or the like can be mentioned. You may add these processes further.

When the solid-phase polymerized polyester is produced by the polyester production method of the present invention, the fine content of the melt polycondensed polyester supplied in the solid-state polymerization step (d), the content of the film-like material, Alternatively, at least one of the total content of the fine content and the film-like material content is 500 ppm or less, preferably 300 ppm or less, more preferably 100 ppm.
It is desirable that the amount is below, more preferably 50 ppm or less.

As a method for removing fines, a vibrating screen step installed in an intermediate step (e) between the chip forming step (c) and the solid phase polymerization step (d), an air flow classification step by an air flow, or A method of treating the melt polycondensed polyester in a gravity type classification step or the like can be mentioned. You may add these processes further. However, when the content of fines in the melt-polycondensed polyester is low, the object may be achieved without installing a device for removing these fines.

When the polyester according to the present invention is polyethylene terephthalate (hereinafter sometimes referred to as "PET"), it goes through the chip forming step (c) to the solid phase polymerization step (d). The fine and / or film-like substance contained in the melt-polycondensed polyester supplied has a melting peak temperature of 2 on the highest side of the melting peak temperature.
When the temperature exceeds 65 ° C, the solid-state PET obtained in the solid-state polymerization step (d) also has a fine peak or film-like substance whose melting peak temperature on the highest side of the melting peak temperature exceeds 265 ° C. For the above reasons, the crystallization rate of the molded product from the solid-phase-polymerized polyester obtained becomes too fast, and its fluctuation becomes very large, and the obtained preforming product for hollow molding is obtained. Whitening occurs, which makes normal stretching impossible, uneven thickness occurs, the transparency of the obtained hollow molded article deteriorates, and the fluctuation of transparency becomes large, which may cause a serious problem.

As a method for preventing inclusion of fine and / or film-like substances having a melting peak temperature on the highest temperature side of the melting peak temperature exceeding 265 ° C., for example, the following method is used. Can be mentioned. That is, after the melt polycondensation, the polyester melted from a die is extruded into water and cut in water, or extruded into the atmosphere and immediately cut with cooling water to be cut into chips, and then formed into chips. After draining the melted polycondensed polyester chips that have been removed, chips, fines, and film-like substances of shapes other than the prescribed size are removed by a vibration sieving process and an airflow classification process using an air flow. Send to storage tank. The chips are withdrawn from the tank by a screw feeder and to the next step by a plug transportation method or a bucket conveyor method, and immediately before the solid-state polymerization step (d) by air flow. A fine air removal process is performed by providing an air flow classification process or a vibration type sieving process.
Further, the molten polycondensed polyester from which the fine or film-like matter has been removed is again subjected to a fine or film-like process by an air stream classification process using an air flow immediately before the solid-state polymerization step (d), or a vibrating sieving step. It is also possible to remove the particulate matter and directly add it to the solid phase polymerization step (d).
When transporting melt-polycondensed polyester chips to a solid-state polymerization facility, or when transporting polyester chips after solid-state polymerization to a sieving process, a contact treatment process with water, or a storage tank, most of these transportations are carried out. Adopts a plug transportation method or a bucket type conveyor transportation method, and uses a screw feeder to extract chips from the crystallization device or solid-state polymerization reactor. Use a device that can minimize the impact on piping.

The melt polycondensed polyester thus obtained is solid-phase polymerized by a conventionally known method in the solid-phase polymerization step (d). First, the melt polycondensed polyester to be subjected to solid-phase polymerization is heated at a temperature of 100 to 210 ° C. for 1 to 5 hours under an inert gas or under reduced pressure, or an atmosphere of steam or an inert gas containing steam. Pre-crystallized. Then, solid phase polymerization is performed at a temperature of 190 to 230 ° C. for 1 to 30 hours in an inert gas atmosphere or under reduced pressure. In the case of polyester having an intrinsic viscosity of 1.0 or more used for direct blow, the solid phase polymerization time may exceed 30 hours. After solid phase polymerization, if necessary, under reduced pressure or in an inert gas atmosphere, about 1
It is cooled to 50 to 50 ° C or lower. Here, the solid phase polymerization step (d) means from after the chip forming step (c) to immediately before the post step (f) after the solid phase polymerization.

The solid-phase polymerized polyester is used for the contact treatment step with water, which will be described later in the transportation pipe, the thermoplastic resin compounding step, the transportation of silos for storage, flexible containers, etc.
It is transported to a storage container or a molding process.
When such chips are transported by a forced low-density transportation method using air, for example, like the above-mentioned melt polycondensation polyester chips, the surface of the solid-phase-polymerized polyester chips is collided with a pipe by collision. A large impact force is applied, and as a result, a large amount of fines and film-like substances are generated as in the case of the melt polycondensed polyester. Such a fine or film-like substance has the effect of promoting crystallization of the polyester as in the case of the polyester after the melt polycondensation, and when it is present in a large amount, the transparency of the obtained molded product is improved. Becomes very bad. In addition, such fines and film-like materials have a melting point of about 1 from the normal melting point.
Those having a melting point higher than 0 to 20 ° C. are included. Also,
Even when solid-phase polymerization is performed using a rotary solid-state polymerization device, or when a feeding device that applies impact force or shear force to the solid-state polymerization polyester chip is used, the melting point is about 10 to 20 ° C or higher than the normal melting point. An extremely large amount of fine particles and films with a high melting point are generated. The reason for the high melting point is the above-mentioned.

About 10 to 20 ° C. from such a normal melting point
When the solid-phase polymerized polyester containing the fine or film-like material having a high melting point is molded under normal molding conditions, such a high melting point crystal is not completely melted during melt molding and remains as a crystal nucleus. As a result, the crystallization rate at the time of heating becomes very fast, and the crystallization of the plug part of the hollow molding container becomes excessive, so that the shrinkage amount of the plug part does not fall within the specified value range, and The problem of capping failure and leakage of contents occurs. In addition, the preform for hollow molding is whitened, which makes normal stretching impossible,
Since the thickness unevenness occurs and the crystallization speed is high, the transparency of the obtained hollow molded article is deteriorated, and the fluctuation of the transparency becomes large, which is a problem.

Therefore, in the method for producing a polyester of the present invention, an intermediate step (g) between the solid phase polymerization step (d) and the subsequent step (f) installed after the solid phase polymerization step (d) is performed. Before the post-process (f) as described above from the polyester subjected to the solid-phase polymerization treatment in the solid-phase polymerization process (d), by adding a fine removal process (h) for removing fines and / or film-like substances. In addition, it is desirable to separate and remove fines and / or film-like substances.

Further, the fine content of the solid-phase polymerized polyester supplied in the subsequent step (f), the content of the film-like material,
Alternatively, at least one of the total content of the fine content and the film-like material content is 500 p.
pm or less, preferably 300 ppm or less, more preferably 100 ppm or less, and further preferably 50 ppm or less.

As a method of removing fines, the solid phase polymerization step (d) and the subsequent step (f) which is installed after the solid phase polymerization step (d) are separately installed in an intermediate step (g). Examples of the method include a vibrating sieving process, an airflow classification process using an air flow, and a gravity classification process. You may add these processes further. Further, when transporting the melt polycondensed polyester to the solid phase polymerization step (d), an apparatus with less generation of fines or the like is used, or an efficient apparatus for removing fines or the like is used in the intermediate step (g) after the solid phase polymerization. When installed, it is also possible to prevent the above problems from occurring without removing fines and the like from the melt polycondensed polyester supplied to the solid-state polymerization apparatus.

Further, in the method for producing polyester of the present invention, the subsequent step (f) means at least one of a contact treatment step with water and a thermoplastic resin compounding step.

In the case where the polyester according to the present invention is PET, the fine peak and / or film-like substance contained in the solid-phase-polymerized polyester has a melting peak temperature on the highest temperature side of the melting peak temperature of 265 ° C. When it exceeds, the crystallization rate of the molded body from the solid-phase polymerized polyester obtained for the above reason becomes too fast, or its fluctuation becomes very large, the preform for hollow molding obtained Whitening occurs, which makes normal stretching impossible, uneven thickness occurs, the transparency of the obtained hollow molded article deteriorates, and the fluctuation of transparency becomes large, which may cause a serious problem.

Therefore, in the case of the polyester having ethylene terephthalate as the main repeating unit obtained by the present invention, the melt pigment of the fine and / or film-like substance contained in the polyester treated by the step of removing fines, etc. -The melting peak at the highest temperature side
The temperature is preferably 265 ° C. or lower.

Therefore, when the polyester obtained by the production method of the present invention is a polyester having ethylene terephthalate as a main repeating unit, it is included in the solid-state polymerized polyester supplied in the subsequent step (f). Fine, melting peak on the highest temperature side of the melting peak
The temperature is preferably 265 ° C. or lower.

As a method for preventing the solid-phase-polymerized polyester from containing fines whose melting peak temperature on the highest side of the melting peak temperature exceeds 265 ° C., the same method and equipment as those for the melt polycondensed polyester are used. Can be used.

In the present invention, as described below, the melting point of fine is measured using a differential scanning calorimeter (DSC), and the melting peak temperature of 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. -If there are multiple melting peaks,
Among the peaks, the melting peak temperature on the highest temperature side is referred to as "the peak temperature on the highest temperature side of the fine melting peak temperature",
In Examples and the like, it is referred to as "fine melting point".

In the process for producing the polyester of the present invention, which comprises the step (a) of removing the low polymer and the step (g) of removing fines, etc., from the low polymer producing step (a) to the chip forming step (c). Solid-state polymerization step (d) to post-step (f)
Can be operated separately, and the production process including the low polymer production process (a) to the post-process (f) can be continuously operated.

The polyester obtained by the production method of the present invention is a mold stain caused by oligomers such as cyclic trimers adhering to the inner surface of the mold, the gas exhaust port of the mold, the exhaust pipe, etc. during molding. In order to further prevent this, contact treatment with water can be carried out after melt polycondensation or solid phase polymerization.

The effect of such contact treatment with water is that the polyester is treated at 290 ° C. in a nitrogen atmosphere by the following method.
Increase in cyclic trimer after melting for 60 minutes at
The amount of increase in cyclic trimer (ΔCT amount) is 0.50% by weight or less, preferably 0.30% by weight or less,
More preferably, it is 0.10% by weight or less.

A method of contact-treating the above polyester chips with water, steam or a gas containing steam will be described below.
Examples of the hot water treatment method include a method of immersing in hot water and a method of spraying water on the chips with a shower. The treatment time is 5 minutes to 2 days, preferably 10 minutes to 1 day, more preferably 30 minutes to 10 hours, and the water temperature is 2 minutes.
The temperature is 0 to 180 ° C, preferably 40 to 150 ° C, more preferably 50 to 120 ° C. The method of industrially performing water treatment is illustrated below, but the method is not limited thereto.
The treatment method may be either a continuous method or a batch method, but the continuous method is preferable for industrial use.

When the polyester chips are subjected to water treatment in a batch system, a silo type treatment tank can be used. That is, the polyester chips are received in silos in a batch system and treated with water. When the polyester chips are treated with water continuously, the polyester chips can be continuously or intermittently received from the upper portion of the tower-type treatment tank for water treatment.

Whether the water treatment method is continuous or batchwise, the number of particles having a particle size of 1 to 25 μm existing in the water introduced from outside the system is X,
The content of sodium is N, the content of magnesium is M,
When the content C of calcium is S and the content of silicon is S, at least one of the following (8) to (12) is satisfied and water treatment is performed. 1 ≤ X ≤ 50,000 (pieces / 10 ml) (8) 0.001 ≤ N ≤ 1.0 (ppm) (9) 0.001 ≤ M ≤ 0.5 (ppm) (10) 0.001 ≤ C ≤ 1 0.0 (ppm) (11) 0.01 ≤ S ≤ 2.0 (ppm) (12)

By setting the number of particles in the water introduced into the water treatment tank and the content of sodium, magnesium, calcium, or silicon within the above range, a metal such as an oxide or hydroxide called a scale is set. The contained substance floats or precipitates in the treated water, or even adheres to the walls of the processing tank or piping, which adheres to and permeates the polyester chips, promotes crystallization during molding, and makes bottles with poor transparency. Can be prevented.

The number of particles in water introduced into the water treatment tank is 500
At least one of the steps up to the supply of natural water such as industrial water to the treatment tank is carried out as a method of reducing the number to 100 pieces / 10 ml or less.
Install devices to remove particles at more than one place. Preferably from the natural water sampling port, to the treatment tank described above, a pipe for returning the water drained from the treatment tank to the treatment tank again, a fine removal device, and the like, to a treatment device including incidental equipment necessary for water treatment An apparatus for removing particles is installed between them, and the content of particles having a particle size of 1 to 25 μm in water supplied to the processing apparatus is set to 1 to 5
It is preferable that the number is 0000 pieces / 10 ml or less. As a device for removing particles, the same device as that used for removing particles in chip cooling water can be mentioned.

In order to reduce sodium, magnesium, calcium and silicon in the water introduced into the water treatment tank, at least one or more of sodium and magnesium are added in the process until natural water such as industrial water is supplied to the treatment tank.
Install a device to remove calcium and silicon. Examples of these devices include the same devices as those used for treating the introduced water in the chip forming step (c).

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 treated as industrial wastewater, a large amount of new water can be used. Not only that, but there is concern that the increase in the amount of wastewater will have an impact on the environment. That is, by returning at least a part of the treated water discharged from the treatment tank to the water treatment tank and reusing it, it is possible to reduce the necessary amount of water, and it is possible to reduce the effect on the environment due to the increase in the amount of drainage. If the wastewater returned to the water treatment tank maintains a certain temperature,
Since the heating amount of the treated water can be reduced, it is preferable that the treated water discharged from the treated layer be returned to the water treated layer and reused. Further, by reusing the water, the flow rate of the treated water in the treated layer can be increased, and as a result, the fines and film-like substances attached to the polyester chips can be washed off, so that an effect of removing the fines is also produced. Here, as the treated water which is discharged from the water treatment tank and then returned to the treatment tank and reused, the overflow of the water treatment tank is used.
There are water discharged from the mouth and treated water discharged from the treatment tank together with the polyester chips, and then separated from the chips.

When the treatment is carried out by contacting the polyester chips with steam or a gas containing steam, 50 to 50
Steam or steam-containing gas or steam-containing air at a temperature of 150 ° C., preferably 50 to 110 ° C. is preferably supplied or present as steam in an amount of 0.5 g or more per 1 kg of granular polyethylene terephthalate. The granular polyethylene terephthalate is contacted with steam. The contact between the polyester chips and steam is usually 10 minutes to 2 days, preferably 20 minutes to 10 days.
Done on time.

The method of industrially carrying out the contact treatment between the granular polyethylene terephthalate and steam or a gas containing steam will be illustrated below, but the method is not limited thereto. Further, the treatment method may be either a continuous method or a batch method.

When the polyester chips are subjected to the contact treatment with steam in a batch system, a silo type treatment apparatus can be used. That is, the polyester chips are received in a silo, and steam or a steam-containing gas is supplied in a batch method to perform contact treatment.

When the polyester chips are continuously contacted with steam, granular polyethylene terephthalate is continuously received from the upper part in a tower-type processing apparatus, and steam is continuously supplied in cocurrent or countercurrent to contact steam. Can be processed. Also in the case of contact treatment with water or steam or a steam-containing gas, either the fine content of the polyester chips before the treatment, the film-like material content, or the total content of the fine content and the film-like material content It is desirable to reduce the content to about 500 ppm or less.

As described above, when treated with water or steam, the granular polyethylene terephthalate is drained by a draining device such as a vibrating screener or a simon cart, and transferred to the next drying step if necessary. To do.

For drying the polyester chips which have been contact-treated with water or steam, a commonly used polyester drying process can be used. As a method for continuously drying, a hopper-type aeration dryer in which polyester chips are supplied from the upper part and a drying gas is aerated from the lower part is usually used.

As a dryer for batch-type drying, drying may be carried out under atmospheric pressure while ventilating a drying 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 molecular weight due to hydrolysis or thermal oxidative decomposition of the polyester.

In the present invention, the polyester thus dried is passed through a sieving step and a fine removal step such as a fine stream by an air stream in the same manner as described above, so that the fine content of the polyester is about 5000 ppm or less, preferably 3000 ppm. It is desirable to reduce the amount to 1000 ppm or less, more preferably 1000 ppm or less, further preferably 500 ppm or less, and most preferably 100 ppm or less.

When the polyester obtained by the production method of the present invention is used for hollow molding, the mouth plug part is subjected to heat crystallization treatment depending on the usage. In some cases, it is difficult to control crystallization due to fluctuations, and in such a case, a large amount of defective products occurs. In order to solve such problems, it is desirable to blend at least one resin selected from the group consisting of polyolefin resin, polyamide resin, and polyacetal resin with the polyester obtained by the production method of the present invention. The blending ratio of the above-mentioned polyolefin resin or the like is 0.1 ppb to 50000 ppm, preferably 0.3 ppb to 10000 ppm, more preferably 0.
5 ppb to 100 ppm, more preferably 1.0 pp
b to 1 ppm, particularly preferably 1.0 ppb to 45 pb
b.

When the blending amount is less than 0.1 ppb, the crystallization rate becomes very slow and the crystallization of the plug part of the hollow molded article becomes insufficient. Therefore, when the cycle time is shortened, the plug part shrinks. Capping failure occurs because the amount does not fall within the specified value range, and the stretch-heat-fixing mold for molding the heat-resistant hollow molded product is heavily contaminated, and the mold is frequently used to obtain a transparent hollow molded product. I have to clean it. If it exceeds 50,000 ppm, the crystallization rate will be high and the crystallization of the plug part of the hollow molded article will be excessive, and the amount of shrinkage and shrinkage of the plug part will not fall within the specified range, resulting in poor capping. Leakage of the product occurs and the preform for the hollow molded body is whitened, which makes normal stretching impossible. Further, in the case of a sheet-like material, if it exceeds 50,000 ppm, the transparency becomes extremely poor, and the stretchability becomes poor, and normal stretching is impossible.
Only a stretched film with large thickness unevenness and poor transparency can be obtained. Further, when the above-mentioned polyolefin resin or the like is used alone, it is hardly effective in preventing stains on the heating die, but it has been found that coexistence with a specific amount of fine is very effective on stains on the die.

In the polyester manufacturing method of the present invention, the polyolefin resin blended with the polyester may be a polyethylene resin, a polypropylene resin, or an α-olefin resin. Further, these resins may be crystalline or amorphous.

In the method for producing polyester of the present invention, examples of the polyethylene resin to be blended with the polyester include homopolymers of ethylene, ethylene and propylene, butene-1,3-methylbutene-1, pentene-1, Other α having about 2 to 20 carbon atoms such as 4-methylpentene-1, hexene-1, octene-1, and decene-1
-Copolymers with olefins and vinyl compounds such as vinyl acetate, vinyl chloride, acrylic acid, methacrylic acid, acrylic acid esters, methacrylic acid esters, and styrene can be mentioned. Specifically, for example, low / medium / high density polyethylene (branched or linear) ethylene homopolymer, ethylene-propylene copolymer, ethylene-butene-1 copolymer, ethylene-4-methyl, etc. Pentene-1 copolymer, ethylene-hexene-1 copolymer, ethylene-octene-1 copolymer, ethylene-vinyl acetate copolymer,
Examples thereof include ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, ethylene-ethyl acrylate copolymers, and other ethylene-based resins.

In the method for producing a polyester of the present invention, examples of the polypropylene resin blended with the polyester include a homopolymer of propylene, propylene and ethylene, butene-1,3-methylbutene-1,
Pentene-1,4-methylpentene-1, hexene-
Other α-olefins having about 2 to 20 carbon atoms such as 1, octene-1, and decene-1, and vinyl compounds such as vinyl acetate, vinyl chloride, acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, and styrene. And the like. Specific examples thereof include propylene-based resins such as propylene homopolymer, propylene-ethylene copolymer, and propylene-ethylene-butene-1 copolymer.

In the method for producing a polyester of the present invention, the α-olefin resin blended with the polyester is, for example, 4-methylpentene-1 homopolymer of α-olefin having about 2 to 8 carbon atoms, And other α-olefins having about 2 to 20 carbon atoms such as ethylene, propylene, butene-1, 3-methylbutene-1, pentene-1, hexene-1, octene-1, and decene-1. And the like. Specifically, for example, butene-1 homopolymer, 4-methylpentene-1
Homopolymer, butene-1-ethylene copolymer, butene-
Examples thereof include butene-1 type resins such as 1-propylene copolymers and copolymers of 4-methylpentene-1 and C _{2 to} C ₁₈ α-olefins.

Further, in the method for producing a polyester of the present invention, examples of the polyamide resin blended with the polyester include butyrolactam, δ-valerolactam,
Polymers of lactams such as ε-caprolactam, enantolactam and ω-laurolactam, 6-aminocaproic acid,
Polymers of aminocarboxylic acids such as 11-aminoundecanoic acid and 12-aminododecanoic acid, hexamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, undecamethylenediamine,
Aliphatic diamines such as 2,2,4- or 2,4,4-trimethylhexamethylenediamine, 1,3- or 1,4-
Alicyclic diamines such as bis (aminomethyl) cyclohexane and bis (p-aminocyclohexylmethane), diamine units such as aromatic diamines such as m- or p-xylylenediamine, and glutaric acid, adipic acid, suberic acid, Polycondensates with aliphatic dicarboxylic acids such as sebacic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, dicarboxylic acid units such as aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid, and copolymers thereof Specifically, for example, nylon 4, nylon 6, nylon 7, nylon 7, nylon 8, nylon 9, nylon 11, 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 6/6
T, nylon 6I / 6T and the like. Further, these resins may be crystalline or amorphous.

In the method for producing a polyester of the present invention, examples of the polyacetal resin blended with the polyester include polyacetal homopolymers and copolymers. As a method for making the polyacetal homopolymer, the density measured by the measuring method of ASTM-D792 is 1.40 to 1.42 g / cm ³ , and AS is AS.
According to TMD-1238 measurement method, 190 ° C., load 21
Melt flow ratio (MFR) measured at 60 g is 0.5 to
Polyacetal in the range of 50 g / 10 minutes is preferred.

Further, as the polyacetal copolymer,
The density measured by the method of ASTM-D792 is 1.
38 to 1.43 g / cm ³ , a polyacetal copolymer having a melt flow ratio (MFR) measured at 190 ° C. and a load of 2160 g of 0.4 to 50 g / 10 min by the measuring method of ASTMD-1238 was obtained. preferable. Examples of these copolymerization components include ethylene oxide and cyclic ethers.

Further, the thermoplastic resin such as the above-mentioned polyolefin resin is blended with the polyester, and the thermoplastic resin is directly added to the polyester so that the content thereof is in the above range, and the mixture is melt-kneaded. In addition to the conventional method such as a method of adding as a batch and melt-kneading, the thermoplastic resin, the production step of the polyester, for example, during melt polycondensation, immediately after melt polycondensation, immediately after pre-crystallization, during solid phase polymerization. , Directly after solid phase polymerization, or at any stage, such as after finishing the manufacturing stage to reaching the molding stage, directly added as powder or granular material, or under the flow condition of polyester chips. It is also possible to use a method in which the above-mentioned thermoplastic resin member is mixed by a method such as bringing it into contact with the member and then melt-kneaded.

Here, as a method for bringing the polyester chip-shaped body into contact with the above-mentioned thermoplastic resin member under a flow condition, the polyester chip-like member is prepared in the empty space where the above-mentioned thermoplastic resin member is present. It is preferable to bring the members into collisional contact with each other. Specifically, for example, during a production process such as immediately after melt polycondensation of polyester, immediately after pre-crystallization, immediately after solid-phase polymerization, or at a transportation stage as a product of polyester chips. A part of the aerodynamic transport pipe, gravity transport pipe, silo, magnet part of the magnet catcher, etc. when filling and discharging the transport container of Or lining with the above-mentioned thermoplastic resin, or the above-mentioned thermoplastic resin part such as a rod-shaped or net-like body in the transfer path. The by, for example installation, and a method of transferring the polyester chips. The contact time of the polyester chip with the member is usually an extremely short time of about 0.01 second to several minutes, but a small amount of the thermoplastic resin can be mixed into the polyester.

Further, in the present invention, in order to produce a polyester having an appropriate crystallization rate and giving a small variation in crystallization rate, the polyester is treated before being contacted with the member made of the thermoplastic resin. In addition, by treating the polyester in a sieving process for removing fines and film-like substances and a removal process such as fines by an air stream, the fine content of polyester, the film-like substance content, or the fine content and film-like substance content. It is desirable to reduce the content of any one of the total content to 500 ppm or less.

On the other hand, when the member made of the thermoplastic resin and the polyester are contact-treated, it is preferable that the thermoplastic resin is present in a state of being adhered to the surface of the polyester chip. The thermoplastic resin member may be a polyester chip depending on the magnitude of the impact force when it collides with the member, the pressure force when contacting the member, or the impact resistance and peeling resistance of the thermoplastic resin member. There is also a state in which it is mixed with the above-mentioned contact-treated polyester chip in a state where it does not adhere to, that is, in a state independent of the polyester chip.

The molded product obtained from the polyester in such a mixed state has a very high crystallization rate or a very large fluctuation in the crystallization rate. In the case of a preformed body for a hollow molded body, only a hollow molded body having a large transparency and whitening and transparency unevenness, normal stretching is impossible, and large thickness unevenness and poor transparency can be obtained. Usually, they are present as fine fine particles, but sometimes the average particle size is about 0.5 to
In some cases, it may be mixed in the contact-treated polyester in the form of granules or agglomerates having a size of several mm independently of the polyester chips. In such a case, the thermoplastic resin becomes a foreign substance in the obtained molded product, and as a result, the resulting molded product has many defects such as unevenness in thickness, voids, and whitening. Therefore, it is desirable to remove the fine particles, particles or lumps of the thermoplastic resin existing independently of the polyester chips before molding.

The method for separating and removing the fine particles, particles or lumps of the thermoplastic resin from the polyester which has been contact-treated with the member made of the thermoplastic resin includes the following methods. That is, after melt-polycondensed polyester or solid-phase polymerized polyester is contact-treated with a member made of the above-mentioned thermoplastic resin, it is treated by a vibration sieving step and a stream classification step by an air flow, or a washing step with ion-exchanged water. The thermoplastic resin in the form of fine granules, granules and lumps is removed by a method such as the method described above, or a method of performing a floating selection treatment. The method of separating and removing the fine particles, particles or lumps of the thermoplastic resin as described above is also effective as a method of removing the polyester fines or film-like materials described below.

In the polyester production step, the melt polycondensation step (b) to the solid phase polymerization step (d), the melt polycondensation step (b) or the solid phase polymerization step (d) to the sieving step, air stream classification step, etc. It is filled into containers such as silos, hoppers of molding machines, and containers for transportation via each step of, but generally, a polyester blower or the like is used for transporting and drying polyester between these steps. It is used by incorporating air in the vicinity into the process. Traditionally, such air
Use it untreated, or use JIS B
It was generally used only after being processed by a cleaner equipped with a low-performance filter unit such as type 3 defined in 9908 (1991). However, when the air treated in such a process is used, there is a problem that only a molded product having poor transparency can be obtained.

Therefore, in the polyester production method of the present invention, the melt polycondensation step (b), the chip forming step (c), the solid phase polymerization step (d), the post step (f), the fine removal step (h), etc. As a gas that comes into contact with the polyester in at least one step of
Out of the system in which the number of particles of m is 1,000,000 particles / cubic feet or less, preferably 100,000 particles / cubic feet or less, more preferably 10,000 particles / cubic feet or less, most preferably 1000 particles / cubic feet or less. It is desirable to use more introduced gas.

Particles having a particle diameter of less than 0.3 μm in a gas are not particularly specified, but a smaller amount is preferable in order to obtain a resin giving a transparent molded body.
The number of particles having a particle size of less than 0.3 μm is preferably 100.
00000 pieces / cubic foot or less, more preferably 50
00000 pieces / cubic foot or less, more preferably 2
It is less than or equal to 000000 pieces / cubic foot.

A method for controlling the number of particles having a particle size of 0.3 to 5 μm in the gas introduced from the outside of the system to 1,000,000 particles / cubic foot or less is illustrated below, but the present invention is not limited to this. is not.

Particle size in gas introduced from outside the system 0.3 to 5
As a method of reducing the number of particles of μm to 1,000,000 / cubic feet or less, a cleaning device for removing the particles at least at one or more places during the process until the gas introduced from the outside comes into contact with the polyester chips Set up. In the case where the gas is air in the vicinity of these processes or equipment, the JIS introduced in the process until the air introduced by the blower from the air inlet comes into contact with the polyester chips.
A gas purifier equipped with a type 1 or / and type 2 filter unit defined in B 9908 (1991) is installed, and the number of particles having a particle size of 0.3 to 5 μm in the air is 1,000,000 / cubic fission. -It is preferable that In addition, JIS B 990 is installed in the air intake port described above.
It is possible to extend the life of the filter unit by installing the gas cleaning device equipped with the filter unit of the type 3 defined in 8 (1991) and using it together with the gas cleaning device equipped with the filter unit. Is.

JIS B 99 for removing particles in gas
As a material of the ultra-high performance filter (hereinafter referred to as HEPA filter) unit of type 1 defined in 08 (1991), a filter paper made of glass fiber can be mentioned.
Examples of the material of the high performance filter unit of the type 2 defined by JIS B 9908 (1991) include a filter made of polypropylene fiber, a filter made of a laminated body of polytetrafluoroethylene film and PET fiber cloth, and the like. Generally, an electrostatic filter made of polypropylene fiber is used. In addition, JIS B 990
The material of the low-performance filter unit of the type 3 defined in 8 (1991) includes non-woven fabric made of PET or polypropylene. The lower limit of the number of particles with a particle size of 0.3 to 5 μm is 10 particles / cubic foot, and in order to make it below this lower limit, enormous equipment investment is required and the operating cost is also very high. Very economical production is difficult.

According to the method for producing a polyester of the present invention, the intrinsic viscosity is 0.60 to 2.00 deciliter / gram, the acetaldehyde content is 10 ppm or less, and the cyclic 3
The content of the monomer is 0.5% by weight or less, and the number of spherulites generated when the molded plate obtained by injection molding is crystallized at elevated temperature is 1 × 1.
It is possible to obtain a polyester having ethylene terephthalate as the main repeating unit in the range of 0 ⁹ to 15 × 10 ⁹ units / m ² . The intrinsic viscosity of the polyester obtained by the production method of the present invention is 0.60 to 2.00 deciliters / gram, preferably 0.65 to 1.80 deciliters / gram, and more preferably 0.70 to 1.50 deciliters / gram. Is the range. Intrinsic viscosity is 0.60
If it is less than deciliter / gram, the mechanical properties of the obtained molded product and the like are poor. On the other hand, if it exceeds 2.00 deciliters / gram, the resin temperature becomes high when melted by a molding machine or the like, and thermal decomposition becomes severe, and free low-molecular-weight compounds that affect aroma retention are increased, or a molded product is obtained. Will be colored yellow.

The content of diethylene glycol copolymerized in the polyester obtained by the production method of the present invention is 0.5 to 5.0 mol% of the glycol component constituting the polyester, preferably 1 It is from 0.0 to 4.5 mol%, more preferably from 1.5 to 4.0 mol%. In order to produce a polyester in which the content of diethylene glycol does not exceed 0.5 mol%, a large amount of a basic compound must be added, in which case the thermal stability of the polyester will be poor, and the polyester will not be colored. May become awful. Further, when the content of diethylene glycol exceeds 5.0 mol%, the content of acetaldehyde increases to 10 ppm or more, which causes a problem in flavor property.

The acetaldehyde content of the polyester obtained by the production method of the present invention is 10 ppm or less, preferably 8 ppm or less, more preferably 5 ppm.
The following is desirable. If it exceeds 10 ppm, the flavor property becomes a problem. Further, if it is 1 ppm or less, solid phase polymerization takes a long time, and it is not practical from the viewpoint of economy.

The content of the cyclic trimer of polyester obtained by the production method of the present invention is 0.50% by weight or less, preferably 0.45% by weight or less, more preferably 0.40% by weight or less. Is desirable. When the content of the cyclic trimer exceeds 0.50% by weight, oligomers such as the later-described cyclic trimer may form on the inner surface of the mold, the gas exhaust port of the mold, the exhaust pipe, etc. during molding. Staining of the mold due to the adhesion is a serious problem. Further, in order to reduce the content of the cyclic trimer to 0.20% by weight or less, solid phase polymerization takes a long time, which is not practical in terms of economy.

Furthermore, the polyester obtained by the production method of the present invention has a thickness of 3 mm obtained by melt injection molding.
The number of spherulites generated when the test piece from the molded body of No. 1 is crystallized at elevated temperature is in the range of 1 × 10 ⁹ to 15 × 10 ⁹ pieces / m ² , preferably 2 × 10 ^{9 to} 12 × 10 ^9. range of pieces / m ^2, and more preferably 3 × 10 ⁹ ~10 × 10 ⁹ pieces / m ²
It is preferably in the range of.

There are many problems in producing a polyester having a spherulite number of less than 1 × 10 ⁹ pieces / m ² such as high equipment cost and very poor productivity. The spherulite number is 15
When it exceeds × 10 ⁹ pieces / m ² , the transparency of the heat-resistant hollow molded article decreases, and the transparency becomes a problem especially in a large hollow molded article of 1.5 liters or more.

Here, the number of spherulites at the time of temperature crystallization of the molded product for specifying the polyester of the present invention is the thermomechanical analysis (TMA), type TM manufactured by Mac Science Co., Ltd.
The molded plate was heat-treated using A4000S and measured by the method described below.

The fine content of the solid-phase polymerized polyester obtained by the method for producing polyester of the present invention is 5
000 ppm or less, preferably 3000 ppm or less, more preferably 1000 ppm or less, further preferably 5
It is desirable to reduce it to 00 ppm or less, most preferably 100 ppm or less. When the application is a hollow molded article, the fine content is preferably 500 ppm or less.

Preferred examples of the polyester according to the present invention include ethylene terephthalate units of 99.5-9.
It is a polyethylene terephthalate (PET) containing 5.0 mol% and having a copolymerized diethylene glycol content of 0.5 to 5.0 mol%. As another example of polystel, ethylene terephthalate unit is 99.0-8.
5.0 mol%, the content of copolymerized diethylene glycol in the glycol component was 0.5 to 5.0 mol, and the content of copolymerized isophthalic acid in the dicarboxylic acid component was 0. 5 to 10 mol% of polyethylene terephthalate-isophthalate copolymer, 99.0 to 85.0 mol% of ethylene terephthalate units, and the content of copolymerized diethylene glycol in the glycol component is 0.5 to
5.0 mol, and the content of copolymerized ethylene-2,6-naphthalate units in the dicarboxylic acid component was 0.5.
10 mol% polyethylene terephthalate-naphthalate copolymer, ethylene terephthalate unit 99.0
To 85.0 mol%, the content of copolymerized diethylene glycol in the glycol component is 0.5 to 5.0 mol, and the copolymerized cyclohexane dimethanol in the glycol component is contained. A polyethylene terephthalate-cyclohexylene terephthalate copolymer having a content of 0.5 to 10 mol% and an ethylene terephthalate unit of 99.0 to 8
5.0 mol%, the content of copolymerized diethylene glycol in the glycol component is 0.5 to 5.0 mol, and the copolymerized neopentyl glycol is contained in the glycol component. An example is a polyethylene terephthalate copolymer having an amount of 0.5 to 10 mol%.

The polyester obtained by the production method of the present invention is a PET obtained by using a raw material such as dimethyl terephthalate or terephthalic acid recovered by purifying a used PET bottle by a chemical recycling method as at least a part of the starting material, Flake PE that is used PET bottle purified by mechanical recycling method and collected
It can be used as a mixture with T or PET in the form of chips.

It is also possible to simultaneously use a saturated fatty acid monoamide, an unsaturated fatty acid monoamide, a saturated fatty acid bisamide, an unsaturated fatty acid bisamide, etc. in the polyester obtained by the production method of the present invention.

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, and ricinoleic acid amide. Examples of the saturated fatty acid bisamide include methylenebisstearic acid amide, ethylenebiscapric acid amide, ethylenebislauric acid amide, ethylenebisstearic acid amide, ethylenebisbehenic acid amide, hexamethylenebisstearic acid amide, and hexamethylenebisbehenic acid. Examples include amides. Examples of unsaturated fatty acid bisamides include ethylenebisoleic acid amide and hexamethylenebisoleic acid amide. Preferable amide compounds are saturated fatty acid bisamide, unsaturated fatty acid bisamide and the like. The compounding amount of such an amide compound is 1
It is in the range of 0 ppb to 1 × 10 ⁵ ppm.

Further, the polyester obtained by the production method of the present invention contains a metal salt compound of an aliphatic monocarboxylic acid having 8 to 33 carbon atoms such as naphthenic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid and stearin. Acids, behenic acid, montanic acid, melissic acid, oleic acid, lithium salts of saturated and unsaturated fatty acids such as linoleic acid, sodium salts, potassium salts, magnesium salts,
It is also possible to use a calcium salt, a cobalt salt, etc. together. The compounding amount of these compounds is 10 ppb
Is in the range of up to 300 ppm.

The polyester obtained by the production method of the present invention can be preferably used as a hollow molding, a packaging material such as a tray or a biaxially stretched film, a film for coating a metal can, and the like. Further, the polyester obtained by the production method of the present invention can be used as a constituent layer of a multilayer molded body, a multilayer film or the like. The polyester obtained by the production method of the present invention can be used for forming films, sheets, containers, and other packaging materials by using a commonly used melt molding method. Further, it is possible to improve the mechanical strength by stretching such a polyester in at least a uniaxial direction. PET will be described below as a typical example.

PET obtained by the production method of the present invention
The stretched film consisting of a sheet-like material obtained by injection molding or extrusion molding is prepared by using any stretching method of uniaxial stretching, sequential biaxial stretching and simultaneous biaxial stretching which are usually used for stretching PET. Molded. It is also possible to form into a recup shape or a tray shape by pressure forming or vacuum forming.
In producing a stretched film, the stretching temperature is usually 80 to 130 ° C. The stretching may be uniaxial or biaxial, but biaxial stretching is preferable from the viewpoint of practical physical properties of the film. If the stretching ratio is uniaxial, it is usually 1.1 to 10.
Double, preferably 1.5 to 8 times, and if biaxially stretched, it is usually 1.1 to 8 in both the machine direction and the transverse direction.
Double, preferably 1.5 to 5 times. The longitudinal magnification / lateral magnification is usually 0.5 to 2, preferably 0.7 to 1.3. The obtained stretched film is
Further, heat fixing can be performed to improve heat resistance and mechanical strength. The heat setting is usually carried out under tension at 120 to 240 ° C., preferably 150 to 230 ° C. for usually several seconds to several hours, preferably several tens of seconds to several minutes.

In producing a hollow molded article, a briform formed from PET obtained by the production method of the present invention is stretch blow-molded.
The apparatus used in the blow molding can be used. Specifically, for example, a preform is once molded by injection molding or extrusion molding, and as it is or after processing the plug portion and the bottom portion, it is reheated, and biaxial stretch blow molding such as hot parison method or cold parison method. The law applies. The molding temperature in this case, specifically, the temperature of each part of the cylinder and nozzle of the molding machine is usually 260 to 290 ° C.
Is the range. The stretching temperature is usually 70 to 120 ° C., preferably 90 to 110 ° C., and the stretching ratio is usually 1.5 in the machine direction.
˜3.5 times, and 2 to 5 times in the circumferential direction.
The obtained hollow molded article can be used as it is, but in the case of beverages such as fruit juice and oolong tea which require heat filling, generally, heat-setting treatment is further performed in a blow mold to obtain heat resistance. It is used by imparting sex. The heat setting is usually carried out under tension such as compressed air at 100 to 200 ° C., preferably 120 to 180 ° C. for several seconds to several hours, preferably several seconds to several minutes.

Further, in order to impart heat resistance to the spout,
The plug part of the preform obtained by injection molding or extrusion molding is crystallized in an oven equipped with a far infrared or near infrared heater, or the plug part is molded with the above heater after bottle molding. Crystallize. In the polyester obtained by the production method of the present invention, other additives as necessary, for example, known ultraviolet absorbers, antioxidants, oxygen absorbers, oxygen scavengers, lubricants added from the outside or during reaction You may mix | blend various additives, such as a lubricant, a mold release agent, a nucleating agent, a stabilizer, an antistatic agent, a dye and a pigment, which were deposited inside.

When the polyester obtained by the production method of the present invention is used for a film application, calcium carbonate is added to the polyester composition in order to improve handling properties such as slipperiness, winding property and blocking resistance. Inorganic particles such as magnesium carbonate, barium carbonate, calcium sulfate, barium sulfate, lithium phosphate, calcium phosphate, and magnesium phosphate; organic salt particles such as terephthalate salts such as calcium and calcium oxalate, barium, zinc, manganese, and magnesium; Inert particles such as crosslinked polymer particles such as homopolymers or copolymers of vinyl monomers of divinylbenzene, styrene, acrylic acid, methacrylic acid, acrylic acid or methacrylic acid can be contained. In addition, the measuring method of the main characteristic value in this invention is demonstrated below.

[0152]

EXAMPLES The present invention will now be specifically described 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 invention 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 (hereinafter referred to as [DEG content]) Decomposition with methanol, the DEG content was quantified by gas chromatography, and expressed as a ratio (mol%) to all glycol components. expressed.

(3) Acetaldehyde content (hereinafter referred to as "A
"A content") Sample / distilled water = 1 g / 2 ml is put in a glass ampoule that has been purged with nitrogen, the upper part is sealed and extracted at 160 ° C for 2 hours, and after cooling, acetaldehyde in the extract is a highly sensitive gas. It was measured by chromatography and the concentration was expressed in ppm.

(4) Content of cyclic trimer of polyester (CT content) A sample is dissolved in a hexafluoroisopropanol / chloroform mixture solution, and chloroform is further added to dilute it. Methanol is added to this to precipitate the polymer, which is then filtered. The filtrate was evaporated to dryness, the volume was made constant with dimethylformamide, and the cyclic trimer composed of ethylene terephthalate units was quantified by liquid chromatography.

(5) Measurement of fine content and film-like material content About 0.5 kg of resin was used 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) having a metal mesh of mm was placed on the sieve in which the two stages were combined, and sieved with a rocking type sieving tow machine SNF-7 manufactured by Terraoka at 1800 rpm for 1 minute. This operation was repeated, and a total of 20 kg of the resin was sieved. If, in addition to the film-like material, two or more chips fused to each other or a chip-like material cut into a size larger than the normal shape are captured on the sieve (A), The remaining film-like material from which the syrup was removed and the fines sieved off under the sieve (B) were separately washed with ion-exchanged water, filtered with a G1 glass filter manufactured by Iwaki Glass Co., Ltd., and collected. These are put together with the glass filter in a dryer at 100 ° C.
After drying for 2 hours, it was cooled and weighed. The same operation of washing with ion-exchanged water and drying was repeated again to confirm that the weight became constant, and the weight of the glass filter was subtracted from this weight to obtain the fine weight and the weight of the film-like material.
Fine content or film content is fine weight or film weight / total screened resin weight. The total content is calculated from these values.

(6) Measurement of melting peak temperature of fine differential scanning calorimeter (DS) manufactured by Seiko Denshi Kogyo KK
C), measured using RDC-220. In (5),
Fines collected from 20 kg of polyester were dried under reduced pressure at 25 ° C for 3 days, and a sample of 4 m was used for each measurement.
DSC measurement at a temperature rising rate of 20 ° C./min using g,
The melting peak temperature on the highest side of the melting peak temperature is determined. The measurement is performed on a maximum of 10 samples, and the average value of the melting peak temperatures on the highest temperature side is obtained.

(7) Number of spherulites during temperature rising crystallization of molded body A test piece of 8 mm x 10 mm was cut out from a plate portion having a thickness of 3 mm from the stepped molded plate of (10) below to obtain a measurement sample. . The molded plate has a molecular orientation derived from the flow at the time of molding, but the orientation state varies depending on the site of the molded plate. Therefore, by sandwiching the molding plate between two polarizing plates whose polarization planes are orthogonal to each other, and observing the intensity distribution of the light passing through the molding plate when irradiating visible light from the direction perpendicular to the polarizing plate surface, the alignment is performed. I confirmed the condition. A test piece was cut out from a site that did not include nonuniform molecular orientation (orientation degree, orientation fluctuation, etc.) within the above dimensions.

At that time, the direction of the optical anisotropy is confirmed in advance, and the relationship with the direction of the test piece to be cut out is as follows. The orientation of the optical anisotropy was determined by a method described in New Polymer Experiment 6 Polymer Structure (2) (Kyoritsu Shuppan Co., Ltd.) using a polarizing microscope and a sensitive color inspection plate. The test piece was cut out so that the direction of the axis of small refractive index (axis of high light velocity) and the long axis of the test piece were parallel to each other. The disordered orientation and the unevenness of the cut surface introduced when cutting out the test piece significantly affect the measurement result. Therefore, the unevenness of the cut surface and the part in which the orientation was disturbed were removed by using a cutter to obtain a flat surface. In addition, the density of the test piece and the degree of molecular orientation also affect the results. The values of density and birefringence are 1.3345 to 1.3355, respectively.
It should be g / cm ³ and 1.30 × 10 ^{−4 to} 1.50 × 10 ⁻⁴ . The density was measured using a water-based density gradient tube, using a resin sampled from the vicinity of the test piece collection site as a sample. Birefringence is determined by a polarizing microscope (EC manufactured by Nikon
LIPSE E600 POL) was used to measure by the Berek compensator method.

As the measured value, the value obtained at the center of the test piece was adopted. The test piece prepared as described above was subjected to thermomechanical analysis (TMA), type TMA manufactured by Mac Science Co., Ltd.
Heat treatment was performed at 4000S. 0.2g constant compression load, A
In an atmosphere of r, the temperature was raised from room temperature to 210 ° C at a rate of 27 ° C / min.
The temperature is lowered at a rate of 7 ° C./min., And the number of spherulites is measured by the following method.

A Leica microtome RM2065 is used to prepare a 2 μm-thick section from the end of the test piece. This section is observed using a Nikon polarization microscope ECLIPSE E600POL. For observation, halogen lamp light was used as a light source, and monochromaticization was not performed by an interference filter or the like. The optical system is adjusted to a so-called crossed nicols state in which the optical axes of the polarizer and the analyzer are orthogonal to each other, and a sensitive color inspection plate of 530 nm is inserted in the optical path. The image is a color CCD camera (HITACH) connected to a polarization microscope.
I HV-C205) and save it as a still image on a Macintosh computer via an image capture board.

When observing the section with the above optical system,
Many spherulites are observed. When a 530 nm sensitive color inspection plate is inserted into the optical path for observation, the spherulites show symmetry reflecting the orientation of the optical anisotropy inside them. Specifically, spherulites are observed as if they were divided into four with their centers being symmetrical. Then, different colors are exhibited in the parallel direction and the vertical direction with respect to the axis having a low refractive index of the sensitive color inspection plate (parallel to the insertion direction). This color is an interference color when the retardation generated by the inspection plate increases with the sample and an interference color corresponding to the case where it decreases, and the azimuth of the optical axis of the inserted inspection plate and the optical inside the spherulites. Determined by the relationship of anisotropic orientation.

105 μm × 79 on the sample using a CCD camera
Take a picture of the μm area and save it in a computer recording device (such as a hard disk or magneto-optical disk).
From this image, the number of spherulites is measured using the image processing software Ultimage / Pro (Image and Measurement Co., Ltd.) on a Macintosh computer according to the following procedure. As described above, spherulites have two kinds of colors. Threshold level is set so that only one of the colors remains, and binarization is performed. By this operation, only the portion having one color is the measurement target. In addition, Primary Morp
Erosion in the hology menu is Number of integrations = 1
Run with. By this operation, the portions which are originally belonging to different spherulites but are connected are separated. After executing this operation, execute the Particle menu and read the value of Detected particles. At this time,
Particles with an area of 4 pixels or less are not measured. Since two particles are measured per spherulite, the value obtained by dividing the value of Detected particles read earlier by 2 is taken as the number of spherulites.

(8) Haze (% of haze) A sample was cut from the body (wall thickness of about 0.45 mm) of the following (10) molded body (wall thickness 5 mm) and (11) hollow molded body. Measured with a haze meter manufactured by Color Co., Ltd.

(9) Foreign matter of hollow molded body Three hollow molded bodies of the following (11) were visually observed, averaged, and evaluated as follows. ◎: There is no foreign matter ○: Very small amount of foreign matter (3 or less foreign matter having a size of 0.5 mm or less per hollow molded body) △: 0.5 mm or more per hollow molded body 5 to 10 foreign matter x: Very large number (more than 10 foreign matter having a size of 0.5 mm or more per hollow molding)

(10) Molding of Stepped Molded Plate A dried polyester is manufactured by Meiki Seisakusho M-150C (D
M) Molded by an injection molding machine at a cylinder temperature of 290 ° C. using a stepped flat plate mold cooled to 10 ° C. The obtained stepped molded plate was 2, 3, 4, 5, 6, 7, 8,
It is equipped with 9,3,11 mm thick plates of about 3 cm x about 5 cm square in a stepwise manner, and the weight of one piece is about 146.
It is g. A plate with a thickness of 3 mm is used for measuring the number of spherulites at the time of heating, and a plate with a thickness of 5 mm is used for measuring haze (% haze).

(11) Molding of Hollow Molded Body Polyester was dried with a dryer using nitrogen, and the resin temperature was 2 with an M-150C (DM) injection molding machine manufactured by Meiki Seisakusho.
The preform was molded at 95 ° C. The plug part of this preform is heated and crystallized by a homemade plug part crystallization device, and then biaxially stretch blow molded using a LB-01 stretch blow molding machine manufactured by Co-Poplast Co., Ltd., and subsequently at about 145 ° C. It was heat-fixed in the mold set as above to obtain a 2000 cc hollow molded body.

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

(13) Average density of polyester chips,
Preform mouth plug density Measured at 30 ° C with a density gradient tube of a calcium nitrate / water mixed solution.

(14) Water content adhering to polyester chips The water content was measured by the Cal-Fisher water content measuring method with the temperature of the water vaporizer set to 230 ° C. and the measurement time of 9 minutes.

(15) Leakage Evaluation of Contents from Hollow Molded Body The hollow molded body molded in the above (11) was filled with 90 ° C. hot water, capped with a capping machine, and then the container was laid down and left to stand. I investigated the leak. In addition, the state of deformation of the spout after capping was also examined.

(16) Sensory test The biaxially stretched blow hollow molded article molded in the above (11),
Distilled water at 70 ° C., which had been boiled and cooled, was placed therein, sealed and held for 30 minutes, cooled to room temperature, and allowed to stand at room temperature for 1 month. After opening, the flavor, smell and the like were tested. As a blank for comparison,
Uses distilled water. 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

(17) Sodium content, calcium content, magnesium content, and silicon content in the introduced water introduced into the chip forming step, the introduced water was collected, and the 1G1 glass filter manufactured by Iwaki Glass Co., Ltd.
After filtering with, the filtrate was measured with an inductively coupled plasma emission spectrometer manufactured by Shimadzu Corporation.

(18) Chemical oxygen demand (COD) (mg / l) of the introduced water introduced into the chip forming step The introduced water filtered by the glass filter used in the above (17) is specified in JIS-K0101. Measure according to the method.

(19) Particle Size and Number of Particles in Introduced Water Introduced into Chiping Process Light-shielding particle measuring instrument HIAC / ROYCO. Manufactured by Pacific Scientific Company. Counter 4
The measurement was performed using a 100 type and a sampler 3000 type.

(20) Measurement of Number of Particles in Gas Contacting Polyester The gas sent by a blower or the like for forcibly sending the gas, which has passed through the gas cleaning device, is branched from the main gas stream before coming into contact with the polyester. It is introduced into a particle measuring instrument and measured.
The measurement is repeated 5 times, the average value is obtained, and the number per 1 cubic foot of gas is calculated. As the particle measuring instrument, a light scattering type particle measuring instrument KC-01B manufactured by Rion Co., Ltd. was used.

Example 1 A slurry of high-purity terephthalic acid and ethylene glycol was continuously fed to a continuous first esterification reactor containing a reactant in advance, and the mixture was stirred under a pressure of about 1%. The reaction was performed at 250 ° C. and 0.5 kg / cm ² G for an average residence time of 3 hours. This reaction product was sent to the second esterification reactor and stirred at about 260 ° C. at 0.05 kg / cm 2.
^The reaction was performed with ² G to a predetermined degree of reactivity. Further, crystalline germanium dioxide was heated and dissolved in water, ethylene glycol was added thereto, and a heat-treated catalyst solution and ethylene glycol solution of phosphoric acid were separately fed continuously to the second esterification reactor. . This esterification reaction product is continuously fed to the first polycondensation reactor and stirred at about 265 ° C.
Polycondensation is performed at 25 torr for 1 hour, then at the second polycondensation reactor under stirring at about 265 ° C. for 3 hours at 3 torr, and further at the final polycondensation reactor at about 275 ° C. for 0.5 to 1 torr for 1 hour. It was

Industrial water (derived from river runoff water) was treated with a coagulating sedimentation device, a filter-filtration device, an activated carbon adsorption device and an ion exchange device, and about 51 particles having a particle size of 1 to 25 μm were obtained.
0 pieces / 10ml, sodium content 0.05ppm,
Magnesium content 0.02ppm, calcium content 0.03ppm, silicon content 0.10ppm, C
Introduced water having an OD of 0.7 mg / l is introduced into the cooling water storage tank in the chip forming step. Molten polycondensed PET extruded continuously in the form of strands is chipped while being cooled with cooling water of 20 ° C. from the above tank, and the discharged water from the chipping step is a continuous filter having a filter medium made of paper and having a thickness of 30 μm. After the treatment with the fine removal device and the activated carbon adsorption tower for adsorbing ethylene glycol and the like, almost the entire amount is returned to the cooling water storage tank and mixed with the introduced water. This cooling water is continuously circulated and the shortage is replenished from outside the system to be used as cooling water. Further, water V of the cooling water is about 2800 cm ³ / sec, the surface area S of the melt polycondensation polyester to be cooled is about 3300 cm ² / sec,
The ratio (V / S) was about 0.85, and the PET cooling time (t) was 8 seconds.

The intrinsic viscosity is 0.55, and the attached water content is about 150.
The fine poly-condensed PET of 0 ppm was transported to the vibrating sieving step and the air stream classifying step to remove fines and film-like substances, whereby the fine content was reduced to about 25 ppm or less.

This resin was overheated and charged into a cleaned continuous solid phase polymerization apparatus. About 155 in a nitrogen atmosphere
Crystallization at ℃, preheat to about 200 ℃ under nitrogen atmosphere, then send to continuous solid-state polymerization reactor about 205 under nitrogen atmosphere.
Solid state polymerization was carried out at ° C. After the solid phase polymerization, the sieving process and the fines removing process were continuously performed to remove the fines and fill the container for storage.

[0182] Incidentally, melt polycondensation PET in the manufacturing process
All chips were shipped using a plug-type shipping system. Also,
According to JIS B 9908 (19), air for sending the melt-polycondensation PET chips to the solid-state polymerization step and air for contacting the solid-state polymerization PET chips with the chips before filling the storage container
91), an air purifier equipped with a type 3 PET non-woven filter unit and JIS B 9908 (199).
Air filtered with an air purifier equipped with a HEPA filter unit having a particle collection rate of 99% or more of type 1) (the number of particles having a particle size of 0.3 to 5 μm is about 550 particles / cubic foot).
It was used. Air filtered in the same manner as in Examples 2 to 3 was used.

PE obtained 3 months after the start of continuous production
The T was evaluated. The obtained PET had an intrinsic viscosity of 0.75 deciliter / gram, a DEG content of 2.8 mol%, an acetaldehyde content of 3.1 ppm, a cyclic trimer content of 0.32% by weight, and a density of 1 .4020 g / c
highest temperature side of the peak of the peak temperature - - m ^3, the content of the fine is about 31 ppm, also fine melting peak peak temperature is 245 ° C.
there were. The residual amount of Ge of the catalytic metal measured by atomic absorption spectrometry was 48 ppm, and the residual amount of P was 30 ppm. The PET was evaluated using a molded plate and a biaxially stretched molded bottle. The haze of the molded plate was 4.2%, and the spherulite number of the molded plate was 3.3 × 10 ⁹ pieces / m ² . The density of the bottle cap portion was 1.378 g / cm ^3, which was a value with no problem, and the foreign matter of the hollow molded article was “⊚ (no foreign matter exists)”, which was not a problem. In addition, in the leak test of the contents, there was no problem and the mouth plug was not deformed. The body haze of the obtained bottle was as good as 1.0%.
The AA content of the bottle was 20.1 ppm, and the sensory test result was 0.6, which was a value with no problem.

(Comparative Example 1) Esterification and melt polycondensation were carried out under the same conditions as in Example 1, and the same industrial water as in Example 1 was treated with an ion exchange device, and the introduced water was used as cooling water for chip formation. The water used for cooling was treated in the same manner as in Example 1 and circulated for use to obtain a melt polycondensed PET.
This molten polycondensed PET is not treated for removal of fine particles,
The obtained PE was placed in an overhole and a cleaned continuous solid-state polymerization apparatus and solid-phase polymerized in the same manner as in Example 1.
T was subjected to molding without removing treatment such as fines. In addition, melt polymerization PET or solid phase polymerization PET in the manufacturing process
Was transported by the low density transportation method.

Particles having a particle size of 1 to 25 μm contained in the introduced water introduced as cooling water at the time of chip formation are about 598300.
Pieces / 10 ml, the sodium content was 1.0 ppm, the magnesium content was 0.8 ppm, the calcium content was 0.9 ppm, the silicon content was 2.5 ppm, and the COD was 3.9 mg / l. The temperature of the cooling water is 5 ℃
And the water amount V is about 8800 cm ³ / sec, and the surface area S of the molten polycondensed polyester to be cooled is about 3300 cm ² /
sec, the ratio (V / S) was about 2.7, and the PET cooling time was 200 seconds.

PE obtained 3 months after the start of continuous production
The T was evaluated. Intrinsic viscosity of melt polycondensed PET is 0.55
Deciliter / gram, the attached water content was about 5900 ppm. The PET obtained had an intrinsic viscosity of 0.74 deciliters / gram and an acetaldehyde content of 3.3 pp.
m, the content of the cyclic trimer is 0.33% by weight, and the density is 1.
4019g / cm ³ , fine content is about 6200p
It was pm. The peak temperature on the highest side of the fine peak temperature was 275 ° C. In addition, a considerable amount of yellow to brown foreign matter was present in the fines. These PETs were evaluated using a molded plate and a biaxially stretched molded bottle. The haze of the formed plate was 22.5%, and the spherulite number of the formed plate was 30.3 × 10 ⁹ pieces / m ² .

The density of the bottle cap is 1.398 g.
/ Cm ³ is too high, and the foreign matter in the hollow molded article is “× (existing in large numbers)” and has no commercial value. The body haze of the obtained bottle was 8.3%, which was a very bad problem. In the leak test of the contents, leakage of the contents was found. The AA content of the bottle was 22.0 ppm, but the sensory test result was 3.3, which is a bad problem.

[0188]

EFFECTS OF THE INVENTION According to the present invention, a molded product such as a hollow molded product containing almost no foreign matter and excellent in transparency and flavor can be provided, and a polyester having improved operability can be advantageously obtained. it can.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Koji Yoshida             1-1, Nada-cho, Iwakuni-shi, Yamaguchi Toyobo Co., Ltd.             Company Iwakuni Factory (72) Inventor Yoshitaka Eto             20 No. 248 Takashiro, Shiga Town, Shiga District, Shiga Prefecture F-term (reference) 4F070 AA47 AB09 DA11 DB09                 4J029 AA03 AB04 AC01 AC02 AD01                       AD10 AE01 BA03 BA04 BA05                       BA10 BB13A BD06A BF09                       BF25 BF26 CA02 CA06 CB05A                       CB06A CB10A CB12A CC06A                       KE01 KE05 KE07 KE08 KE12                       KE15 KF01 KH03 KH08

Claims (10)

[Claims] 1. A low-polymer production step (a) for esterifying or transesterifying a dicarboxylic acid containing terephthalic acid or an ester-forming derivative thereof with a glycol containing ethylene glycol or an ester-forming derivative thereof.
The melt polycondensation step (b) in which the low polymer obtained in the low polymer production step is melt-polycondensed, and the melt polycondensed polyester obtained in the melt polycondensation step are subjected to chemical oxygen demand (COD ) Is introduced from outside the system, and the cooling time (t) of the polyester is (2)
And a chip forming step (c) for forming chips while cooling with cooling water so as to satisfy the above condition. COD ≤ 2.5 (mg / l) (1) 2 (sec) ≤ t ≤ 180 (sec) (2) 2. The water temperature of the cooling water in the chipping step (c) is 7 to 50 ° C., and the water amount V (cm ³ / se) of the cooling water.
Surface area S of melt polycondensed polyester cooled with c)
A chip is formed under the condition that the ratio (V / S) of (cm ² / sec) satisfies the following (3).
The method for producing a polyester according to 1. 0.1 ≤ (V / S) ≤ 2.0 (3) 3. A solid phase polymerization step (d) for solid phase polymerizing the melt polycondensed polyester having an intrinsic viscosity of 0.30 to 0.80 deciliter / gram obtained in the chipping step. The method for producing a polyester according to claim 1 or 2. 4. The amount of water attached to the melt-polycondensed polyester chips sent from the chip forming step (c) to the solid-state polymerization step is 3%.
It is 000 ppm or less, The manufacturing method of polyester of Claim 3 characterized by the above-mentioned. 5. The fine or the like removing step (h) for removing fines and / or film-like substances is added after the chip forming step (c), according to claim 1 or 2. A method for producing the described polyester. 6. An intermediate step (e) between the chip forming step (c) and the solid phase polymerization step (d), or between the solid phase polymerization step (d) and the solid phase polymerization step (d). A feature is that a fine etc. removing step (h) for removing fines and / or film-like substances is added to at least one intermediate step of the intermediate step (g) with the subsequent step (f) installed later. The method for producing the polyester according to claim 3 or 4. 7. A fine content, a film-like material content, or a total content of a fine content and a film-like material content of the melt polycondensed polyester supplied to the solid phase polymerization step (d). One content, or at least one of the fine content of the solid-phase polymerized polyester supplied in the subsequent step (f), the film-like material content, or the total content of the fine content and the film-like material content. Content of one is 500 ppm or less, The manufacturing method of the polyester in any one of Claim 3, 4, 6 characterized by the above-mentioned. 8. The method of claim 3, wherein the subsequent step (f) is at least one of a contact treatment step with water and a thermoplastic resin compounding step.
4. The method for producing a polyester according to any one of 4, 6, and 7. 9. A polyester is used in at least one of the melt polycondensation step (b), the chip forming step (c), the solid phase polymerization step (d), the post step (f), and the fines removing step (h). The gas to be contacted has a particle size of 0.3-5 μ
The method for producing a polyester according to any one of claims 1 to 8, wherein a gas introduced from outside the system, in which m particles are 1,000,000 particles / cubic foot or less, is used. 10. The polyester has an intrinsic viscosity of 0.60.
~ 2.00 deciliters / gram, acetaldehyde content of 10 ppm or less, cyclic trimer content of 0.5% by weight or less, and spherulites formed when a molded plate obtained by injection molding is crystallized by heating. The number is 1 × 10 ⁹ to 15 × 10 ⁹ pieces / m
10. The method for producing a polyester according to claim 3, wherein the polyester is a solid-phase polymerized polyester in the range of ² .