JP2003064173A - Method for polyester production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method with which a polyester hardly containing foreign matters, providing a hollow molding, etc., with excellent transparency, hardly causing mold stain during molding of molding and a polyester slightly increasing filtration pressure of filter are produced. SOLUTION: This method for polyester production comprises subjecting a polyester prepolymer of melt condensation polymerization chipped while using cooling water in which sodium content (N), magnesium content (M), a silicon content (S) and calcium content (C) satisfy at least one of N<=1.0 (ppm) (1), M<=0.5 (ppm) (2), S<=2.0 (ppm) (3) and C<=1.0 (ppm) (4) to solid-phase polymerization.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a bottle, a packaging material such as a film and a sheet, and a tire core.
More specifically, it relates to a method for producing polyester used for fibers for industrial materials such as cords and the like, and more specifically, it gives a hollow molded body having almost no foreign matter and excellent transparency, and the mold is not contaminated during molding. The present invention relates to a method for producing a polyester that does not easily occur and a polyester that is less likely to be clogged with a filter during film formation and spinning and has improved operability.

[0002]

BACKGROUND OF THE INVENTION Polyester is excellent in mechanical strength, heat resistance, transparency and gas barrier property, so that it is especially used for filling beverages such as juices, soft drinks, carbonated drinks, packaging films and audio. It is most suitable as a material for video films and is used in large quantities.

It is also used in large quantities on a global scale as an industrial material such as clothing fibers and tire cords.
Polyesters generally contain a by-product, acetaldehyde. If the content of acetaldehyde in the polyester is high, the content of acetaldehyde in the container and other packaging materials formed from this will also be high, affecting the flavor and odor of the beverage filled in the container, etc. . Therefore, various measures have been conventionally taken to reduce the content of acetaldehyde in polyester, and a typical method is solid-phase polymerization of a melt polycondensation prepolymer.

Such a polyester is supplied to a molding machine such as an injection molding machine to mold a preform for a hollow molded body, the preform is inserted into a mold having a predetermined shape, stretch blow molding is performed, and then a bottle body is formed. It is general that a part is heat-treated (heat set) to be molded into a hollow molded container, and if necessary, a bottle cap is heat-treated (crystallized cap).

The melt polycondensation polyester prepolymer is
After completion of the melt polycondensation, the product is extruded through the pores and made into chips while being cooled with cooling water. Using distilled water as cooling water in this chip formation process is disadvantageous in terms of cost,
It is common to use industrial water that is a simple treatment of water, groundwater, drainage, etc. from rivers. However, when the cooling treatment is carried out using industrial water, there is often a problem that the flavor and aroma of the content of the obtained molded container become very bad, and this solution has been 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 results of studies by the present inventors, it was found that, in the chipping process, organic particles and organic compounds originating in nature-derived bacteria, bacteria, etc. contained in industrial water, and spoiled plants and animals. It has been found that when the content of the above is a certain value or more, these substances are adsorbed and permeated on the surface of the polyester chip, and have an adverse effect on the flavor and odor of the contents of the molding container. Further, when the content of metal-containing substances such as sodium, magnesium, calcium, silicon (silicic acid) contained in industrial water exceeds a certain value, metal-containing substances such as oxides or hydroxides of these metals It was found that it adheres to and permeates polyester chips, promotes crystallization during molding, and becomes a bottle with poor transparency. Further, since the metal-containing substance adheres to the cooling tank or the cooling water pipe in the chip forming process as a scale, there arises a problem that it is difficult to clean these. In particular, the inclusion of sodium does not cause scale, but sodium ions permeate into the surface layer of the chip, and crystallization proceeds with the sodium ions as nuclei, which is a major factor for whitening the bottle.

The metal-containing substance attached to the surface of the chip in the chip forming step and brought into the solid-state polymerization reaction device is fixed to the vessel wall of the solid-state polymerization device together with a part of the surface layer of the polyester chip. However, this becomes a scale with a high metal content and adheres to the vessel wall by heating for a long time at a high temperature of about 170 ° C. or higher. 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.

When manufacturing a film or fiber,
There is also a problem in that the above-mentioned scale is clogged with the molten polymer filtration filter during spinning or film formation, the filtration pressure of the filter increases sharply, and the operability and productivity deteriorate.

[0009]

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 hollow molded article having excellent transparency, etc., and a method for producing a polyester in which a mold stain is unlikely to occur during molding of the molded article and a polyester having a small increase in filtration pressure of a filter.

[0010]

In order to achieve the above object, a method for producing a polyester according to the present invention comprises a sodium content (N), a magnesium content (M), a silicon content (S) and calcium. Content (C) of (1) to (4) below is used for solid phase polymerization of the melt-polycondensed polyester prepolymer which is made into chips while being cooled using cooling water. Is a method for producing a polyester. N ≤ 1.0 (ppm) (1) M ≤ 0.5 (ppm) (2) S ≤ 2.0 (ppm) (3) C ≤ 1.0 (ppm) (4)

In this case, at least water treated with an ion exchange device can be used as the cooling water in the chip forming step.

In this case, fine and / or film-like substances can be removed from the melt polycondensed polyester prepolymer and / or the polyester after the solid phase polymerization.

In this case, the content of any one of the fine content of the polyester before the solid-state polymerization, the film content, or the total content of the fine content and the film content is 500 ppm or less. Can be

In this case, the fine content of the solid-phase polymerized polyester can be 5000 ppm or less.

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 polyester may be a polyester containing ethylene terephthalate as a main repeating unit and having an intrinsic viscosity of 0.55 to 2.0 deciliter / gram.

In this case, the polyester has ethylene terephthalate as a main repeating unit, an intrinsic viscosity of 0.67 to 1.5 deciliter / gram, an acetaldehyde content of 10 ppm or less, and a cyclic trimer content of 0.5. Weight% or less, fine content of 500 ppm or less, haze of the molded plate obtained by injection molding is 15% or less, and crystallization temperature of the molded plate when measured by DSC (hereinafter referred to as "Tc1"). There is) 150-17
It can be a polyester in the range of 5 ° C.

When the main repeating unit is a polyester composed of ethylene terephthalate, the peak temperature on the highest melting peak side of the fine particles contained in the solid-phase polymerized polyester is 265 ° C. or less. Can be

Here, as described below, the melting point of fine was measured using a differential scanning calorimeter (DSC), and D
The melting peak temperature of SC 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. -In the case of a plurality of melting peaks, the melting peak temperature on the highest temperature side among these plural melting peaks is defined as "the peak temperature on the highest temperature side of the fine melting peak temperature". In the examples and the like, it is referred to as “fine melting point”.

In this case, the solid-phase-polymerized polyester described above can be treated by contact with water.

In this case, at least one resin selected from the group consisting of a polyolefin resin, a polyamide resin and a polyacetal resin can be blended with the solid-phase polymerized polyester.

[0022]

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 preferably a crystalline polyester obtained mainly from an aromatic dicarboxylic acid component and a glycol component, and more preferably a polyester in which the aromatic dicarboxylic acid unit contains 85 mol% or more of the acid component. And particularly preferably a polyester in which the aromatic dicarboxylic acid unit contains 95 mol% or more of the acid component.

The aromatic dicarboxylic acid component constituting the polyester according to the present invention includes terephthalic acid, 2,6-
Examples thereof include aromatic dicarboxylic acids such as naphthalenedicarboxylic acid, diphenyl-4,4′-dicarboxylic acid and diphenoxyethanedicarboxylic acid, and functional derivatives thereof.

Examples of the glycol component constituting the polyester according to the present invention include ethylene glycol, trimethylene glycol, tetramethylene glycol, alicyclic glycols such as cyclohexanedimethanol, and the like. Examples of the acid component to be used by copolymerization in the polyester include aromatic compounds such as terephthalic acid, 2,6-naphthalenedicarboxylic acid, isophthalic acid, diphenyl-4,4'-dicarboxylic acid and diphenoxyethanedicarboxylic acid. Oxy acids such as group dicarboxylic acids, p-oxybenzoic acid, oxycaproic acid and their functional derivatives, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, succinic acid, glutaric acid, dimer acid and their functional derivatives, Examples thereof include alicyclic dicarboxylic acids such as hexahydroterephthalic acid, hexahydroisophthalic acid and cyclohexanedicarboxylic acid, and functional derivatives thereof.

Examples of the glycol component used by copolymerization in the polyester include aliphatic glycols such as ethylene glycol, trimethylene glycol, tetramethylene glycol, diethylene glycol and neopentyl glycol, bisphenol A and bisphenol A. Examples thereof include aromatic glycols such as alkylene oxide adducts of polyethylene glycol, polyalkylene glycols such as polyethylene glycol and polybutylene glycol.

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

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

In another preferred example of the polyester according to the present invention, the main repeating unit is ethylene-2,6-.
A polyester composed of naphthalate, more preferably 8 units of ethylene-2,6-naphthalate units.
A linear polyester containing 5 mol% or more, and particularly preferably a linear polyester containing 95 mol% or more of ethylene-2,6-naphthalate units, that is, a polyethylene naphthalate homopolymer or copolymer.

Other preferred examples of the polyester according to the present invention include linear polyesters containing 85 mol% or more of propylene terephthalate units, linear polyesters containing 85 mol% or more of 1,4-cyclohexanedimethylene terephthalate units, or It is a linear polyester containing 85 mol% or more of butylene terephthalate units.
The above polyester can be produced by a conventionally known production method. That is, in the case of PET, after terephthalic acid, ethylene glycol and, if necessary, other copolymerization components are directly reacted to distill off water and esterify,
A direct esterification method in which polycondensation is carried out under reduced pressure, or dimethyl terephthalate and ethylene glycol and, if necessary, other copolymerization components are reacted to distill off methyl alcohol for transesterification, and then polycondensation is carried out under reduced pressure. It is produced by the transesterification method. Then increase the intrinsic viscosity,
Solid phase polymerization is performed to reduce the acetaldehyde content and the like. In order to accelerate crystallization before solid-phase polymerization, the melt-polymerized 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 melt polycondensation reaction may be carried out in a batch reactor or a continuous reactor.
In any of these methods, the melt polycondensation reaction may be carried out in one step or may be carried out in multiple steps. The solid phase polymerization reaction can be carried out by a batch type apparatus or a continuous type apparatus as in the melt polycondensation reaction. The melt polycondensation and solid phase polymerization may be carried out continuously or may be carried out separately.

An example of a preferable continuous production method will be described below using polyethylene terephthalate as an example. First, the case of producing a low polymer by an esterification reaction will be described. A slurry containing 1.02 to 1.5 mol, preferably 1.03 to 1.4 mol of ethylene glycol per 1 mol of terephthalic acid or its ester derivative was prepared, and this slurry was continuously subjected to the esterification reaction step. To supply

In the esterification reaction, water or alcohol produced by the reaction is removed from the system in a rectification column under the condition that ethylene glycol is refluxed by using a multistage apparatus in which at least two esterification reactors are connected in series. While removing. The temperature of the first stage esterification reaction is 240 to
270 ° C, preferably 245-265 ° C, pressure 0.2
~ 3 kg / cm ² G, preferably 0.5-2 kg / cm ²
G. The temperature of the last stage esterification reaction is usually 25
0 to 280 ° C., preferably 255 to 275 ° C., the pressure is usually 0 to 1.5 kg / cm ² G, preferably 0 to 1.
It is 3 kg / cm ² G. When it is carried out in three or more stages, the reaction conditions for the intermediate stage esterification reaction are
It is a condition 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, the esterification reaction rate is 90% or more, preferably 93%
It is desirable to reach the above. A low-order condensate having a molecular weight of about 500 to 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 chain of polyethylene terephthalate can be improved. It is preferable because the ratio of the dioxyethylene terephthalate component unit can be maintained at a relatively low level (5 mol% or less based on the total diol component).

Next, when a low polymer is produced by a transesterification reaction, 1.1 to 1.6 mol, preferably 1.2 to 1.5 mol of ethylene glycol is added to 1 mol of dimethyl terephthalate. The contained solution is prepared and continuously fed to the transesterification reaction step.

In the transesterification reaction, methanol produced by the reaction is removed to the outside of the system by 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. While doing. 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, and as a transesterification catalyst, Zn,
Fatty acid salts such as Cd, Mg, Mn, Co, Ca and Ba,
Carbonate, Pb, Zn, Sb, Ge oxide or the like is used. Due to these transesterification reactions, the molecular weight is about 200-500.
A low order condensate 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 can be 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 obtained low-order condensate is supplied to a multi-stage liquid phase condensation polymerization process. Regarding the polycondensation reaction conditions, the reaction temperature of the first stage polycondensation is 250 to 290 ° C., preferably 260 to 280 ° C., and the pressure is 500 to 20 Torr.
r, preferably 200 to 30 Torr, and the temperature of the final polycondensation reaction is 265 to 300 ° C., preferably 275.
The pressure is 10 to 0.1 Torr, preferably 5 to 0.5 Torr. When it is carried out in three or more stages, the reaction conditions of the polycondensation reaction in the intermediate stage 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 a solution obtained by adding ethylene glycol to the solution and heating it is used. However, in particular, in order to obtain the polyester used in the present invention, it is preferable to use a solution in which germanium dioxide is dissolved in water by heating or a solution in which ethylene glycol is added and heated. These polycondensation catalysts can be added during the esterification process. When a Ge compound is used, the amount of the Ge compound used is 10 to 150 ppm, preferably 13 to 100 ppm, and more preferably 15 to 70 p as the residual Ge amount in the polyester.
pm.

Examples of the Ti compound include tetraalkyl titanates such as tetraethyl titanate, tetraisopropyl titanate, tetra-n-propyl titanate and tetra-n-butyl titanate, and 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. Examples of the Sb compound include antimony trioxide, antimony acetate, antimony tartrate, potassium antimony tartrate, antimony oxychloride, antimony glycolate, antimony pentoxide, triphenyl antimony and the like.

The Sb compound is added so that the amount of Sb remaining 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 an alkali metal or its compound is used, it is particularly preferable to use Li, Na or K. Examples of the alkali metal or alkaline earth metal compound include, for example, saturated aliphatic carboxylic acid salts such as formic acid, acetic acid, propionic acid, butyric acid and oxalic acid, and unsaturated aliphatic carboxylic acid salts such as acrylic acid and methacrylic acid. , Aromatic carboxylic acid salts such as benzoic acid, halogen-containing carboxylic acid salts such as trichloroacetic acid, hydroxycarboxylic acid salts such as lactic acid, citric acid and salicylic acid, carbonic acid, sulfuric acid, nitric acid, phosphoric acid, phosphonic acid, hydrogen carbonate, phosphorus Inorganic acid salts such as oxyhydrogen, hydrogen sulfide, sulfurous acid, thiosulfuric acid, hydrochloric acid, hydrobromic acid, chloric acid and bromic acid, organic sulfonic acid salts such as 1-propanesulfonic acid, 1-pentanesulfonic acid and naphthalenesulfonic acid , Organic sulfates such as lauryl sulfate, methoxy, ethoxy, n
-Propoxy, iso-propoxy, n-butoxy, t
alkoxides such as ert-butoxy, chelate compounds with acetylacetonate, hydrides, oxides,
A hydroxide etc. are mentioned. 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. The amount of the alkali metal compound or the alkaline earth metal compound is 1 to 50 pp as the residual amount of these elements in the produced polymer.
Add so that it is in the range of m.

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 melt polycondensed polyester prepolymer thus obtained is solid-state polymerized. The above polyester is solid-phase polymerized by a conventionally known method. First, the polyester to be subjected to solid-phase polymerization is pre-crystallized by heating at a temperature of 100 to 210 ° C. for 1 to 5 hours under an inert gas, a reduced pressure, or an atmosphere of steam or a steam-containing inert gas. It 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.

The melt polycondensed polyester prepolymer 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 it is disadvantageous in terms of cost to use distilled water as cooling water in the chip forming step, it is common to use water from rivers, groundwater, drainage, etc., or industrial water obtained by simply treating these.

However, when the cooling treatment is carried out using industrial water, the flavor and aroma of the contents of the obtained molding container become very bad, and the crystallization of the obtained polyester during molding is too early. There is also a problem that the bottle becomes poorly transparent, and the shrinkage of the plug portion due to crystallization of the plug portion does not fall within the standard, resulting in poor capping. Also,
Scales metal compounds in industrial water by heating for a long time
Becomes a polymer and adheres to the reactor wall of the solid-state polymerization device, which sometimes peels off or fuses to the chip surface and mixes into the polyester chip, becoming foreign matter in the molded product such as bottles and the commercial value. There was a problem of lowering.

In the polyester production method of the present invention, the sodium content (N), the magnesium content (M), the silicon content (S) and the calcium content (C) are the following (1): The above-mentioned problems are solved by solid-phase polymerizing the molten polycondensed polyester prepolymer which is made into chips while cooling with cooling water satisfying at least one of (4) to (4). N ≤ 1.0 (ppm) (1) M ≤ 0.5 (ppm) (2) S ≤ 2.0 (ppm) (3) C ≤ 1.0 (ppm) (4) Note that (1) to It is preferable to use water that satisfies all of (4).

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

The lower limits of the sodium content (N), the magnesium content (M), the silicon content (S) and the calcium content (C) in the cooling water are N ≧
0.001ppm, M ≧ 0.001ppm, S ≧ 0.0
It is preferable that 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. On the contrary, the crystallization speed may be too slow, the range of crystal shrinkage may not meet the standard, and capping failure of the spout part may occur in the case of a bottle.

Cooling water whose sodium content (N), magnesium content (M), silicon content (S) and calcium content (C) satisfy the above (1) to (4). The transparency of the molded product from the polyester obtained by solid-state polymerization of the melt polycondensed polyester prepolymer that is chipped while cooling with is extremely excellent, and the filter during spinning is less clogged and the operability is very high. Stabilize.

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

In order to reduce sodium, magnesium, calcium, and silicon in the cooling water, a device for removing sodium, magnesium, calcium, and silicon is installed at at least one place in the process until industrial water is sent to the chip cooling process. To do. 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, 500 particles having a particle diameter of 1 to 25 μm existing in water introduced from outside the system as chip cooling water are used.
It is desirable to use water made up to 100 pieces / 10 ml or less. The number of particles having a particle size of 1 to 25 μm in the introduced water is preferably 10,000 particles / 10 ml or less, more preferably 5 particles.
000 pieces / 10 ml or less, more preferably 2000 pieces / 10 ml or less, particularly preferably 1000 pieces / 10 ml
It is the following.

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 polyester which gives a transparent molded product or 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.

50,000 particles / 10 ml of particles having a particle size of 1 to 25 μm in the introduced water to be introduced in the chip forming step below.
The control method is illustrated below, but the present invention is not limited to this.

The number of particles having a particle size of 1 to 25 μm in the cooling water is 5
As a method for reducing the number to 0000 pieces / 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. Preferably, a device for removing particles is installed between the natural water sampling port and the chipping step, and the content of particles having a particle size of 1 to 25 μm in water supplied to the chipping step is set. The number is preferably 50,000 pieces / 10 ml or less. As a device for removing particles, a filter filtration device,
Membrane filtration devices, settling tanks, centrifuges, foam entrainers, etc. may be 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. In order to efficiently remove particles and efficiently introduce water, the size of the filter mesh is 5 to 100 μm, preferably 1 μm.
The thickness is preferably 0 to 70 μm, more preferably 15 to 40 μm. In addition, it is preferable to filter with these filters and then with a filter having a mesh size of about 1 μm.

The lower limit of the number of particles having a particle size of 1 to 25 μm in water is not particularly specified, but it is preferably 1 particle / 10 ml or more, more preferably 10 particles / 10 ml or more. If the number of particles having a particle size of 1 to 25 μm in water is set to less than 1 particle / 10 ml, the equipment may become large, which may be disadvantageous in terms of economical production.

Further, it is preferable to use the cooling water for the chips while repeatedly recycling them, from the viewpoint of improving the economical efficiency and the productivity. A filter, a temperature controller, a device for removing impurities such as acetaldehyde, and the like can be provided during the cooling water recycling process. Further, a device for removing the above particles, sodium, magnesium, calcium, and silicon can be provided.

In the manufacturing method of the present invention, the shape of the polyester chips may be any of cylinder type, square type, spherical type or flat plate type. Its average particle size is usually 1.5
˜5 mm, preferably 1.6 to 4.5 mm, more preferably 1.8 to 4.0 mm. For example, in the case of a cylinder type, the length is 1.5 to 4 mm and the diameter is 1.5.
It is practically about 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. Further, it is practical that the weight of the chip is in the range of 10 to 30 mg / piece.

The polyester melt-polycondensed as described above is chipped and then transported in a storage pipe to a storage silo or a solid-state polymerization step. 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 polyester chips due to a collision with a pipe, and as a result, fines or film-like substances are generated. It occurs in large quantities.

Such fine or film-like material has the effect of promoting the crystallization of polyester, and when it is present in a large amount, the transparency of the obtained molded product becomes very poor. In addition, such fines and film-like substances have a melting point whose peak temperature on the highest side of the melting peak temperature measured as described below is higher than the normal melting point by about 10 to 20 ° C. or more. Things are included. Also, when the solid phase polymerization is carried out using a rotary type solid phase polymerization apparatus, or when a feeder for applying impact force or shearing force to the polyester chips is used as a transportation method to the next step, the melting peak is also used. The peak temperature on the highest temperature side is about 10 from the normal melting point.
An extremely large amount of fines and film-like substances having a melting point higher than 20 ° C. 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.

The fine or film-like material of polyester having a melting point higher than the normal melting point by about 10 to 20 ° C. or more is solid phase polymerized with polyester chips. When treated or subsequently treated such as contact treatment with water, their melting points become higher than before treatment. Further, even in the case of fines or film-like substances having a melting point whose peak temperature on the highest side of the melting peak temperature is not higher than the normal melting point by about 10 ° C. or more, these melting points will not be normal. It has a melting point higher than the melting point by about 10 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.

A polyester containing fine or film-like material having a melting point higher than the normal melting point by about 10 to 20 ° C. is molded under normal molding conditions. In this case, 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 hollow-molding preform is whitened, which makes normal stretching impossible, resulting in uneven thickness, and the high crystallization rate results in poor transparency of the obtained hollow-molded product and also in transparency. Fluctuation also becomes a big problem.

For blow molding with good transparency and stretchability from polyester containing fines, etc., whose peak temperature on the highest side of the melting peak temperature is about 10 to 20 ° C. higher than the normal melting point. In order to obtain a preform or a sheet-like material, it is necessary to carry out melt molding at a temperature higher than the normal melting point by about 30 to 50 ° C or more. However, at such a high temperature, the thermal decomposition of the polyester becomes severe, and a large amount of by-products such as acetaldehyde and formaldehyde are generated, resulting in a great influence on the flavor of the contents such as a molded body. It becomes. Further, when blending a resin such as the following polyolefin resin to the polyester obtained by the production method of the present invention,
Since these resins are often inferior in thermal stability to the polyester according to the present invention, in the molding at a temperature higher than the normal melting point by about 30 to 50 ° C. or more as described above, thermal decomposition occurs to generate a large amount of by-products. Since it is generated, the flavor of the obtained molded product or the like will be further affected.

Therefore, the polyester which has been melt polycondensed in the melt polycondensation step and then made into chips is transported to the fines removing step for separating and removing fines and / or film-like substances, and processed in the next step. before,
It is important to remove as much of these as possible.

Examples of methods for removing fines include a vibrating sieving step separately installed immediately before or after the solid phase polymerization step, a stream classification step by an air flow, a gravity type classification step and the like. . You may add these processes further.

Then, the fine content and / or the film content of the melt polycondensed polyester after the fine and / or film-like material is removed by the fine removal step or the total content of the fine content and the film content. The above problems are solved by making the content of any one of the amounts 500 ppm or less, preferably 300 ppm or less, more preferably 100 ppm.
It is desirable to lower the amount to 50 ppm or less.

In the case of a polyester whose main repeating unit is ethylene terephthalate, most of the melting peak temperature of the fine and / or film-like substance contained in the polyester treated by the fine removing step is the most. When the melt peak temperature on the high temperature side exceeds 265 ° C., the crystallization rate of the polyester obtained by the above-mentioned reason becomes too fast, or its fluctuation becomes extremely large, and the obtained hollow molding The pre-molded body is whitened, which makes normal stretching impossible, resulting in uneven thickness, poor transparency of the obtained hollow molded body, and large fluctuation of transparency, which is a serious problem.

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".

Further, as a method for preventing the inclusion of fine particles whose melting peak temperature on the highest side of the melting peak temperature exceeds 265 ° C., the following method can be mentioned. That is, after melt polycondensation, the molten polyester is extruded into water from a die and cut in water, or extruded into the air and immediately cut with cooling water while cutting into chips, and then formed into chips. After the chips are drained, chips, fines and film-like substances with a shape other than the prescribed size are removed by a vibrating screen process and an air flow classification process using an air flow, and the chips are sent to a storage tank by a plug transport system or a bucket type conveyor-transport system. .

The chips are withdrawn from the tank by a screw type feeder and to the next step by a plug transportation method or a bucket type conveyor transportation method, and immediately before the solid phase polymerization step 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 melt polycondensed polyester which has been subjected to the removal treatment of the fine or film-like material described above is again subjected to an air stream classification step by an air flow immediately before the solid-state polymerization step, or a vibrating sieving step, etc. It is also possible to carry out the removal and directly add it to the solid phase polymerization step. When the melt-polycondensed prepolymer chips are transported to the solid-state polymerization equipment or the polyester chips after the solid-state polymerization are transported to the sieving process, the water treatment process, the storage tank, etc., most of these transportations are plugs. Adopting a transportation method or a bucket type conveyor transportation method, and using a screw feeder to withdraw chips from the crystallization device or the solid-state polymerization reactor, equipment for chips and processes, transportation piping, etc. Use a device that can minimize the impact with.

Further, the above solid-phase polymerized polyester is transported to a fines removing step for separating and removing fines and / or film-like substances, and these are removed as much as possible before being processed in the next step. This is very important. In the present invention, the above problems are solved by setting the fine content of the solid-phase polymerized polyester after removing fines and / or film-like substances in the fines removal step to 5000ppm or less, preferably 3000 ppm or less, more preferably 1
It is desirable to lower it to 000 ppm or less, more preferably 500 ppm or less, and most preferably 100 ppm or less.

Therefore, in the case of the polyester having ethylene terephthalate as the main repeating unit obtained by the present invention, the finest melting peak temperature of the fine peak contained in the polyester treated by the fine removing step is the highest temperature side. The melting peak temperature of 265 ° C. or less solves the above problems.

By the method for producing polyester of the present invention, regardless of whether a batch type solid phase polymerization apparatus or a continuous type solid phase polymerization apparatus is used, continuous production is carried out for a period of from half a year to one year or more. However, solid-state polymerized polyester containing almost no foreign matter and giving a hollow molded article having excellent transparency, and solid-state polymerized polyester having less clogging of the filter during film formation and spinning and improved operability It is possible to obtain

In particular, in the case of a polyester containing ethylene terephthalate as a main repeating unit, it is used as the cooling water in the chip formation of the melt polycondensation prepolymer as described in (1) above.
To a fine content, a film-like material content, or a fine content and a film-like material by removing fine and / or film-like material through a fine removal step using cooling water satisfying at least one of (4) to (4) 500 ppm or less, preferably 300 ppm or less, more preferably 100 ppm or less of any one of the total contents
The solid content of the melt-polycondensed polyester prepolymer is set to 50 ppm or less, preferably 500 ppm or less, preferably 300 ppm or less, more preferably 100 ppm or less.
The haze of a molded plate having a thickness of 5 mm obtained by injection molding is 15% by reducing it to ppm or less, more preferably 50 ppm or less, and most preferably 30 ppm or less.
A solid-state polymerized polyester suitable for use in a hollow molded article, which has the following crystallization temperature (Tc1) of a molded plate having a thickness of 2 mm obtained by injection molding when the temperature is increased: 150 to 175 ° C. Obtainable. The haze of the molded plate is preferably 10% or less, more preferably 8% or less, and the crystallization temperature (Tc1) during heating is preferably 155 to 17%.
The temperature is 0 ° C, and more preferably 158 to 168 ° C.

When the haze of the molded plate exceeds 15%,
The obtained hollow molded article has poor transparency, which is a problem particularly in the case of a stretched hollow molded article. Also, Tc1 is 175 ° C
When it exceeds, the heating crystallization rate becomes very slow, the crystallization of the plug portion of the hollow molded body becomes insufficient, and the problem of leakage of the contents occurs. Further, when Tc1 is less than 150 ° C., the transparency of the hollow molded article decreases, which becomes a problem.

The intrinsic viscosity of the polyester obtained by the production method of the present invention, especially the polyester whose main repeating unit is ethylene terephthalate, is 0.5.
5-2.00 deciliters / gram, preferably 0.6
It is in the range of 0 to 1.70 deciliter / gram, more preferably 0.70 to 1.50 deciliter / gram. When the intrinsic viscosity is less than 0.55 deciliter / gram, the mechanical properties of the obtained molded product and the like are poor. Also, 2.
If it exceeds 100 deciliters / gram, the resin temperature rises when it is melted by a molding machine and the thermal decomposition becomes more intense, the amount of free low molecular weight compounds that affect the aroma retention increases, and the molded product turns yellow. Problems such as do occur.

The polyester obtained by the production method of the present invention, in particular, the main repeating unit is ethylene-
The intrinsic viscosity of a polyester composed of 2,6-phthalate is 0.40 to 1.50 deciliter / gram, preferably 0.42 to 1.00 deciliter / gram, and more preferably 0.45 to 0.90 deciliter / gram. It is in the gram range. When the intrinsic viscosity is less than 0.40 deciliter / gram, the mechanical properties of the obtained molded product are poor. On the other hand, if it exceeds 1.50 deciliters / gram, the resin temperature becomes high during melting by a molding machine or the like, resulting in severe thermal decomposition, increasing the amount of free low molecular weight compounds that affect the aroma retention, Will be colored yellow.

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.
Hereinafter, the formaldehyde content is 7 ppm or less, preferably 6 ppm or less, and more preferably 4 ppm or less. If the acetaldehyde content exceeds 10 ppm or if the formaldehyde content disappears below 7 ppm,
The flavor, smell and the like of the contents such as molded articles obtained from such polyesters are deteriorated.

The amount of diethylene glycol copolymerized with the polyester obtained by the production method of the present invention is 1.0 of the glycol component constituting the above polyester.
˜5.0 mol%, preferably 1.3 to 4.5 mol%, more preferably 1.5 to 4.0 mol%. If the amount of diethylene glycol exceeds 5.0 mol%, the thermal stability becomes poor, the molecular weight decreases significantly during molding, and the acetaldehyde content and formaldehyde content increase undesirably. If the content of diethylene glycol is less than 1.0 mol%, the transparency of the obtained molded product will be poor.

The content of the cyclic trimer of the polyester obtained by the production method of the present invention is 0.5% by weight or less, preferably 0.45% by weight or less, more preferably 0.40% by weight or less. . When a heat-resistant hollow molded article or the like is molded from the polyester of the present invention, heat treatment is carried out in a heating mold, but when the content of the cyclic trimer is 0.5% by weight or more, the heating mold is heated. Adhesion of oligomers to the surface sharply increases, and the transparency of the obtained hollow molded article is extremely deteriorated.

Polyester is solid-phase polymerized in order to prevent mold stains and the like 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 and the like during molding. After that, contact treatment with water is performed.

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 applying 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 20 to 180 ° C., preferably 40 to 150.
C., more preferably 50 to 120.degree.

The method of industrially performing water treatment is illustrated below, but the method is not limited to this. 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 treated with water 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 (5) to (9) is satisfied and water treatment is performed. 1 ≤ X ≤ 50,000 (pieces / 10 ml) (5) 0.001 ≤ N ≤ 1.0 (ppm) (6) 0.001 ≤ M ≤ 0.5 (ppm) (7) 0.001 ≤ C ≤ 1 0.0 (ppm) (8) 0.01 ≤ S ≤ 2.0 (ppm) (9)

By setting any of the number of particles in water to be introduced into the water treatment tank and the content of sodium, magnesium, calcium or silicon within the above range, a metal such as 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 the treatment of chip cooling water.

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.

However, in the treated water discharged from the treatment tank in the water treatment, the fine or film-like material already attached to the polyester chips at the stage of receiving the polyester chips in the treatment tank, the polyester chips themselves or the treated water during the water treatment are treated. It contains polyester fines and film-like substances that are generated by friction with the tank wall. In addition, the new treated water contains fine particles derived from inorganic substances, spoiled plants, and organic fine particles derived from animals.

Therefore, when the treated water discharged from the treatment tank is returned to the treatment tank for reuse, the amount of fines and fine particles contained in the treated water in the treatment tank gradually increases, and the amount of fines contained in the treated water increases. In some cases, film-like substances and fine particles adhered to the wall of the processing tank and the wall of the pipe and clog the pipe.

Fines, film-like substances and fine particles contained in the treated water adhere to the polyester chips, and then fine and film-like substances and fine particles adhere to or permeate the polyester chips at the stage of drying and removing water. Therefore, the content of fine, film-like and fine particles of the polyester becomes very large, the crystallinity of the polyester thus obtained is promoted, and the transparency of the obtained bottle becomes poor, and the bottle mouth The crystallinity at the time of crystallization of the plug part becomes excessive and the size of the mouth plug part does not meet the standard,
As a result, capping of the spigot part and leakage of the contents may occur.

Therefore, in the present invention, the fine content of polyester to be supplied or filled in the water treatment layer,
The content of the film-like material or the total content of the fine content and the film-like material content is about 50.
It is preferable to solve the above problems by limiting the amount to 0 ppm or less, preferably 300 ppm or less, and more preferably 100 ppm or less. If the content of fines, etc. exceeds 500ppm, the content of fines, etc. in the treated water in the treatment tank will rapidly increase, which may clog the pipes, and the amount of fines attached to the treated polyester chips may increase. The crystallinity is promoted by the influence of fines, and when the molded product is a bottle, only a bottle having poor transparency can be obtained.

As a method of reducing the content of polyester fine or film-like substances to be added to the water treatment tank,
For example, a method of passing a polyester chip after solid-phase polymerization through a sieving process or a removing process such as fines by an air flow can be mentioned.

In the present invention, after being discharged from the water treatment tank, at least a part of the water is returned to the treatment tank to be reused. 10 ml or less, preferably 800
It is desirable that the number is maintained at 00 pieces / 10 ml or less, and more preferably at 50,000 pieces / 10 ml or less. Here, the treated water thus returned to the treatment tank and reused is referred to as recycled water.

Below, the particle size of the recycled water is from 1 to 4
A method of reducing the number of particles of 0 μm to 100,000 particles / 10 ml or less is illustrated, but the present invention is not limited to this. The number of particles having a particle size of 1 to 40 μm in the recycled water is 1000
As a method for reducing the number of particles to 100 pieces / ml or less, an apparatus for removing fines and fine particles is installed at at least one place in the process until the treated water discharged from the treating tank is returned to the treating tank again. Examples of the device for removing fines and fine particles include a filter-filtration device, a membrane filtration device, a settling tank, a centrifuge, and a foam entrainment treatment device. For example filter
Examples of the filtration device include automatic self-cleaning system, belt filter system, bag filter system, cartridge filter system, and centrifugal filtration system. 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. Further, in order to remove fines and to efficiently flow the treated water, the size of the mesh of the filter is 5 to 100 μm, preferably 5 to 70 μm.
μm, more preferably 5 to 40 μm.

Further, the water introduced from outside the system can be discharged from the water treatment tank together with the chips and then supplied to the treatment tank together with the treated water to be reused after being subjected to treatment such as filtration. is there.

When the polyester chips and steam or steam-containing gas are brought into contact with each other to be treated, 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.
It will be held for 10 hours.

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 steam or 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 is either It is desirable to reduce the content to about 500 ppm or less as in the case of the water treatment.

As described above, when treated with water or steam, the granular polyethylene terephthalate is drained with a draining device such as a vibrating screener or a simon carter, 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 at 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, such a dried polyester is passed through a sieving step and a fine removal step such as a fine stream by an air flow 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.

[0115] In the hollow molded article, the plug portion of the hollow molded article is heated and crystallized depending on the application, but it may be difficult to control the crystallization due to variations in molding conditions and heating conditions. May occur. In order to solve such a problem, in the production method of the present invention, it is desirable that at least one resin selected from the group consisting of a polyolefin resin, a polyamide resin, and a polyacetal resin is blended with the polyester.

The blending ratio of the above-mentioned polyolefin resin and the like is 0.1 ppb to 50,000 ppm, preferably 0.1.
3 ppb-10000 ppm, more preferably 0.5 p
pb-100 ppm, more preferably 1.0 ppb-
It is 1 ppm, particularly preferably 1.0 ppb to 45 pbb. If the compounding amount is less than 0.1 ppb, the crystallization speed will be very slow and the mouthpiece of the hollow molded article will not be sufficiently crystallized. Therefore, if the cycle time is shortened, the amount of shrinkage of the mouthpiece will be regulated. Capping failure occurs because it does not fall within the value range, and the stretch heat-fixing mold for molding the heat-resistant hollow molded product is heavily contaminated, and the mold is frequently cleaned when trying to obtain a transparent hollow molded product. There must be. 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.

In the case of a sheet-like material, 50,000 pp
If it exceeds m, the transparency becomes extremely poor, and the stretchability becomes poor so that normal stretching is impossible and only a stretched film having large thickness unevenness and poor transparency can be obtained. 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 method for producing polyester of the present invention, examples of the polyolefin resin blended with the polyester include polyethylene resin, polypropylene resin, and α-olefin resin. Further, these resins may be crystalline or amorphous.

In the method for producing a polyester of the present invention, examples of the polyethylene resin 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.

Further, in the method for producing a polyester of the present invention, the α-olefin resin blended with the polyester includes homopolymers of α-olefin having about 2 to 8 carbon atoms such as 4-methylpentene-1 and the like. 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 the polyacetal homopolymer, A
The density measured by STM-D792 is 1.4.
Polyacetal having a melt flow ratio (MFR) of 0 to 1.42 g / cm ³ , measured by ASTM D-1238 at 190 ° C. and a load of 2160 g of 0.5 to 50 g / 10 minutes is preferable.

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 by the measuring method of ASTM D-1238 of 0.4 to 50 g / 10 min was obtained. preferable. Examples of these copolymerization components include ethylene oxide and cyclic ethers.

Further, as a method of blending the thermoplastic resin such as the above-mentioned polyolefin resin with the polyester, a method of directly adding the thermoplastic resin to the polyester so that the content thereof is in the above range and melt-kneading Or, in addition to a conventional method such as a method of adding as a master-batch and melt-kneading, the above-mentioned thermoplastic resin is used in the production step of the polyester, for example, during melt polycondensation, immediately after melt polycondensation, immediately after pre-crystallization. , During solid phase polymerization, immediately after solid phase polymerization, etc., or during the period from the end of the manufacturing stage to the molding stage, etc., as a powder or granules, or polyester chips It is also possible to use a method in which the above-mentioned thermoplastic resin member is mixed under such a flow condition as described above and then mixed 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 flowing conditions, 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. Part of the aerodynamic transport pipe, gravity transport pipe, silo, magnet part of the magnet catcher, etc. when filling / 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 molded product having a small crystallization rate fluctuation, the polyester is contact-treated with a member made of the above-mentioned 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 desirable that the thermoplastic resin is present in a state of being attached 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 too high crystallization rate, or has a very large fluctuation in the rate.

In the case of the hollow molded article preform, the whitening and transparency unevenness are severe, and normal stretching is impossible.
Only hollow molded products with large thickness unevenness and poor transparency can be obtained. Usually, the above contact-treated polyester is present as fine fine particles, but sometimes in the form of granules or agglomerates having an average particle diameter of about 0.5 to several mm, independent of the polyester chips. It may be mixed in. 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.

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.

In the polyester production process, a silo, a hopper of a molding machine, and a transportation process are carried out through the melt polycondensation process to the solid-phase polymerization process, or from the solid-phase polymerization process to the sieving process, airflow classification process, and the like. It is filled in a container such as a container for use in transporting and drying the polyester between these steps, and air in the vicinity of the treatment facility is generally taken into the step by a blower or the like and used. Conventionally, such air is either left untreated or used according to JIS.
It was generally used only after being processed by a cleaner equipped with a low-performance filter unit such as type 3 defined in B 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 method for producing polyester of the present invention, from the step of transporting the polyester chips obtained in the melt polycondensation step to the next step, as the gas to be contacted with the polyester in the subsequent steps,
It is desirable to use a gas having a particle size of 0.3 to 5 μm that is introduced from outside the system of 1,000,000 (pieces / cubic foot) or less.

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.
It is 00000 (pieces / cubic feet) or less, more preferably 5,000,000 (pieces / cubic feet) or less, and further preferably 2000000 (pieces / cubic feet or less).

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

Particle size in gas introduced from outside the system 0.3 to 5
As a method for reducing the number of particles of μm to 1,000,000 (pieces / cubic foot) or less, a cleaning method 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 Install a chemical device.
In the case where the gas is air in the vicinity of the treatment equipment, JIS B 9 is used during the process in which the air introduced by the blower from the air inlet comes into contact with the polyester chips.
908 (1991), a gas purifying apparatus equipped with a type 1 or / and type 2 filter unit is installed, and the number of particles having a particle size of 0.3 to 5 μm in the air is set to 10
It is preferable that the number is 00000 (pieces / cubic foot) or less. In addition, JIS B 99 is installed in the air intake port.
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 08 (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.

In addition, JIS B 9908 (1991)
Examples of the material of the high performance filter unit of the type 2 defined in 1. 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 9908 (1991)
Examples of the material of the low-performance filter unit of the type 3 defined in 1. include non-woven fabric made of PET or polypropylene.

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.

The polyester according to the present invention may contain other additives, if necessary, such as known ultraviolet absorbers, antioxidants, oxygen absorbers, oxygen scavengers, lubricants added from the outside and internal additives during the reaction. You may mix | blend various additives, such as the deposited lubricant, mold release agent, nucleating agent, stabilizer, antistatic agent, and pigment.

The polyester obtained by the above-mentioned production method of the present invention is injection-molded and stretch-blow-molded into a stretched hollow-molded product, a direct blow-molded hollow-molded product, and an extrusion-molded sheet. The material is formed into a film or a film obtained by further stretching the material. Further, it is spun and drawn into a raw yarn for tire cord by an ordinary melt spinning machine.

[0143]

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

(1) Intrinsic viscosity (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 of polyester
Content (hereinafter referred to as [DEG content]) It was decomposed with methanol, the amount of DEG was quantified by gas chromatography, and the content was expressed as a ratio (mol%) to all glycol components.

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

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

(5) Increasing amount of cyclic trimer during melting of polyester (ΔCT amount) 3 g of dried polyester chips were placed in a glass test tube and immersed in an oil bath at 290 ° C. for 60 minutes under a nitrogen atmosphere to melt. Let The amount of cyclic trimer increase during melting is determined by the following formula. Increase of cyclic trimer at melting (wt%) = cyclic 3 after melting
Content of monomer (% by weight) -Content of cyclic trimer before melting (% by weight)

(6) 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.

(7) Measurement of fine melting peak temperature (fine melting point) Differential scanning calorimeter (DS) manufactured by Seiko Denshi Kogyo KK
C), measured using RDC-220. In (6),
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.

(8) Average Density of Polyester Chip, Density of Preform Mouth Portion: Measured at 30 ° C. with a density gradient tube of a calcium nitrate / water mixed solution. Further, the density of the plug portion was determined as an average value of 10 samples crystallized by the method (12).

(9) Crystallization temperature (Tc
1) Differential thermal analyzer (DS) manufactured by Seiko Electronics Co., Ltd.
C), measured with RDC-220. Using 10 mg of a sample from the center of a 2 mm-thick plate of the following (14) molded plate. The temperature is raised at a temperature rising rate of 20 ° C./minute, and the peak temperature of the crystallization peak observed during the heating is measured and used as the crystallization temperature during heating (Tc1).

(10) Haze (% haze) and haze unevenness Samples were cut from the body (wall thickness 5 mm) of (13) and the hollow body (wall thickness approximately 0.45 mm) of (14) below. Measured with a haze meter manufactured by Nippon Denshoku Co., Ltd. Also,
The haze of the hollow molded article which was continuously molded 10 times was measured,
The haze spots were obtained by the following. Haze spot = maximum haze value / minimum haze value

(11) Foreign matter of hollow molded body Three hollow molded bodies of the following (14) 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)

(12) Density increase due to heating of preform mouthpiece The preform mouthpiece was heat treated for 90 seconds by a home-made infrared heater, and a sample was taken from the top surface to measure the density.

(13) Molding of Stepped Molded Plate The dried polyester was 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 having a thickness of 2 mm is used for measuring Tc1 and a plate having a thickness of 5 mm is used for measuring haze (% of haze).

(14) Molding of Hollow Molded Body Polyester is dried with a dryer using nitrogen, and the resin temperature is 2 with an M-150C (DM) injection molding machine manufactured by Meiki Seisakusho.
The preform was molded at 95 ° C. The mouthpiece of this preform was heated and crystallized by a homemade mouthpiece 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 155 ° C. It was heat-fixed in the mold set as above to obtain a 2000 cc hollow molded body.

(15) Leakage evaluation of contents from hollow molded product The hollow molded product molded in the above (14) 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) Introduced water introduced into the chip forming step and sodium content, calcium content, magnesium content, and silicon content introduced water in the introduced water of the water treatment step were collected to obtain 1G1 glass manufactured by Iwaki Glass Co., Ltd. Filter-
After filtering with, the filtrate was measured with an inductively coupled plasma emission spectrometer manufactured by Shimadzu Corporation.

(17) Particle Size and Number of Particles in Introduced Water Introduced in Chiping Step and Introduced Water in Water Treatment Step Particle-blocking device of light-shielding type Pacific Scientific Company HIAC / ROYCO. Counter 4
The measurement was performed using a 100 type and a sampler 3000 type.

(Example 1) Melt polycondensation PET extruded in a strand shape was treated with industrial water (derived from river runoff water) by a filter-filtration device and an ion exchange device to give a particle size of 1
˜25 μm particles about 2550 particles / 10 ml, sodium content 0.05 ppm, magnesium content 0.1.
While being cooled with cooling water having 03 ppm, a calcium content of 0.03 ppm and a silicon content of 0.09 ppm, it was cut into chips by a chipping device. The melt polycondensation prepolymer was transported to a vibrating sieving step and an air stream classifying step to remove fines and film-like substances, thereby reducing the fines content to about 10 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 207 under nitrogen atmosphere.
Solid state polymerization was carried out at ° C. After solid phase polymerization, fine particles were removed by continuous treatment in a sieving step and a fine particle removing step. In addition, in the manufacturing process, all of the melt-polymerized prepolymer chips and the solid-phase polymerized chips were transported by a plug-type transportation system.
The PET obtained 10 days, 3 months and 6 months after the start of continuous production was evaluated. The obtained PETs all have an intrinsic viscosity of 0.75 deciliters / gram, DE
G content is 2.6 to 2.8 mol%, acetaldehyde content is 2.8 ppm to 3.0 ppm, cyclic trimer content is 0.30 to 0.32 wt%, and density is 1.4018 to
1.4020 g / cm ³ , content of fines is 15 to
The peak temperature was 29 ppm, and the peak temperature on the highest side of the fine peak temperature was 245 to 247 ° C. The residual amount of Ge of the catalytic metal measured by atomic absorption spectrometry is 45 to 48 p.
The pm and P residual amount were 30 to 33 ppm.

These PETs were evaluated using a molding plate and a biaxially stretched molding bottle. The haze of the molded plate is 3.5 to 4.6%, and the Tc1 of the molded plate is 169 to 167.
C, the density of the plug part is 1.377 to 1.380 g / cm ^3.
There is no problem with the above, and the foreign matter of the hollow molded article from PET at each of the above-mentioned time points is “◎ (no foreign matter exists)”.
Or, it was "○ (the amount of foreign matter is very small)" and there was no 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 0.9 to 1.5%, and the haze unevenness was 1.1 to 1.3. The AA content of the bottle was 21.0 ppm, which was a value with no problem.

(Example 2) The PET obtained after 6 months of continuous production obtained in Example 1 was treated with water as follows. In addition,
The intrinsic viscosity before water treatment is 0.75 deciliters / gram,
The content of DEG is 2.6 mol%, the content of acetaldehyde is 2.9 ppm, the content of cyclic trimer is 0.31% by weight, the density is 1.4018 g / cm ³ , the content of fines is 15 ppm, and The peak temperature on the highest side of the fine melting peak temperature was 245 ° C. Raw material chip supply port (1) in the upper part of the treatment tank, overflow discharge port (2) located at the upper limit level of the treated water in the treatment tank, and discharge port (3) of the mixture of polyester chips and treated water in the lower part of the treatment tank. ), Oh
The treated water discharged from the flow outlet and the treated water that has passed through the polyester chip drainer (4) discharged from the outlet at the bottom of the processing tank are fine filters whose filter media are paper continuous filters. A pipe (6) which is again sent to the water treatment tank via the filtration removal device (5) and the adsorption tower (8),
GAF filter made by ISP-bag PE-1P2S
Obtained by introducing new ion-exchanged water from the outside of the system through the particle remover in water (polyester felt, filtration accuracy 1 μm) and the ion-exchanger into the inlet (9) in the middle of this pipe (6). The PET chip was continuously subjected to water treatment using a tower-type treatment tank shown in FIG. 1 having an internal volume of 50 m ³ equipped with a water inlet (7).

The above-mentioned solid-state polymerization PET chips were continuously introduced from the upper supply port (1) of the treatment tank controlled to the treatment water temperature of 95 ° C., and the water treatment tank was discharged at the bottom of the treatment tank for 3 hours. The water treatment was performed while continuously extracting the PET chip together with the treated water from (3). The content of particles having a particle size of 1 to 25 μm in the introduced water collected before the ion-exchanged water inlet (9) of the above-mentioned treatment apparatus is about 1900 particles / 10 ml,
Sodium content is 0.02ppm, Magnesium content is 0.02ppm, Calcium content is 0.02pp
m, the silicon content was 0.08 ppm, and the number of particles of the recycled water after treatment in the filtration device (5) and the adsorption tower (8) was 12,000 particles / 10 ml. The PET after the water treatment was continuously dried with a dryer using dehumidified heated air, and then subjected to a treatment for removing fines and the like in a vibrating screen step and an air stream classification step. The obtained PET had an intrinsic viscosity of 0.75 deciliter / gram, a DEG content of 2.6 mol%, a cyclic trimer content of 0.31% by weight, and an increase amount of the cyclic trimer of 0.05% by weight. %, The AA content was 2.8 ppm, the fine content was 10 ppm, and the peak temperature on the highest side of the melting peak temperature was 245 ° C. The melt-polymerized prepolymer in the manufacturing process
A plug type transportation system was used for transportation of chips, solid-state polymerization chips, and chips after water treatment. The PET was evaluated using a molded plate and a biaxially stretched molded bottle. The results are shown in Table 1. The haze of the formed plate is 3.9%, and the T of the formed plate is T.
c1 is 167 ° C., the density of the spout is 1.377 g / cm ³
There was no problem, and 5000 or more continuous stretch blow moldings were carried out, but no mold stain was observed, and the transparency of the bottle was good. In addition, in the leak test of the contents, there was no problem and the mouth plug was not deformed. The obtained bottle had good haze of 1.0%, uneven haze of 1.1, and uneven thickness of 1.03. Foreign matter on the bottle is
(The amount of foreign matter is very small) ”, and there was no problem.
The AA content of the bottle was 16.4 ppm, which was a value with no problem.

Example 3 Water-treated PET previously obtained in Example 2 and linear low-density polyethylene (MI = about 0.
The PET obtained in Example 2 was prepared by kneading 9 g / 10 minutes and a density of about 0.923 g / cm ³ ) by a twin-screw extruder to prepare a PET master in which the polyethylene was finely dispersed.
This master was mixed so that the polyethylene would be about 10 ppb, and a molded plate and a biaxially stretched molded bottle were obtained by the methods (13) and (14). The results are shown in Table 1. The result was fine.

(Example 4) Molten polycondensation polyethylene naphthalate (hereinafter abbreviated as "PEN") extruded in a strand form was used as industrial water (derived from river underflow water) in a filter-filter device and an ion-exchange device. Treated, particle size 1-25
Approximately 2800 particles of 10 μm / 10 ml, sodium content 0.04 ppm, magnesium content 0.02 p
While being cooled with cooling water having pm, a calcium content of 0.03 ppm, and a silicon content of 0.09 ppm, the chips were cut into chips by a chipping device. The melt polycondensation prepolymer was transported to a vibrating sieving step and an air stream classifying step to remove fines and film-like substances, thereby reducing the fines content to about 10 ppm or less. This resin was overheated and charged into a cleaned batch type solid phase polymerization apparatus. After purging with nitrogen, the temperature inside the device was raised while reducing the pressure, pre-crystallization was performed at about 140 ° C, and then crystallization was performed at about 160 ° C, followed by solid-state polymerization at about 240 ° C under about 0.1 torr. And IV1.02 PEN was obtained. After the solid phase polymerization, fine particles are removed by treating with a sieving process to reduce the fine content to 3
It was set to 5 ppm. Batch batch solid phase polymerization was continuously performed for 100 batches, and a 100 ml batch of PEN was used to mold a 300 ml container by a direct blow molding machine.
Foreign substances were inspected according to the evaluation criteria. The foreign matter was "○ (very small amount of foreign matter)" and there was no problem.

(Example 5) Content of fines etc. of melt polycondensation PET (6th month of continuous production) to be introduced into the solid phase polymerization step is about 300ppm, and fines of solid phase polymerization PET to be introduced into the sheet forming step etc. Solid-state polymerization was carried out in the same manner as in Example 1 except that the process conditions were changed so that the content was about 3800 ppm, the intrinsic viscosity was 0.73 deciliter / gram, the acetaldehyde content was about 10 ppm, and the content of the cyclic trimer. Yielded 0.52 wt% PET. This PET
A sheet having a thickness of 0.5 mm was obtained using a home-made sheet film forming machine. A film was formed while filtering with a filter in which three 500-mesh stainless wire meshes were stacked, but the pressure gauge installed in front of the wire mesh filter showed a slight rise, and almost no foreign matter was found in the obtained sheet. . The foreign matter inspection was performed by visually observing a sheet (width of about 1 m × 10 m) to measure the number of foreign matter having a size of 0.5 mm or more.

Comparative Example 1 Melt polycondensation prepolymer chips were prepared in the same manner as in Example 1 except that the industrial water was used as it was as cooling water for chip formation without using the ion exchange apparatus used in Example 1. Got This prepolymer was placed in an overhole and a cleaned continuous solid phase polymerization apparatus without being subjected to a removal treatment such as fine particles, and solid phase polymerization was carried out in the same manner as in Example 1 to obtain PET. It was subjected to molding without removing treatment such as fines. In the manufacturing process, the melt-polymerized prepolymer chips and the solid-phase polymerized chips were transported by the low-density transportation method instead of the same method as in Example 1. Particles having a particle size of 1 to 25 μm contained in the industrial water used as the cooling water at the time of chip formation are about 492300 to 65400.
0 pieces / 10ml, sodium content 4.3-7.5p
pm, the magnesium content was 1.0 to 2.0 ppm, the calcium content was 6.2 to 7.1 ppm, and the silicon content was 10.1 to 15.5 ppm. The PET obtained 3 months after the start of continuous production was evaluated. PET obtained
Has an intrinsic viscosity of 0.75 deciliter / gram, an acetaldehyde content of 2.8 ppmppm, a cyclic trimer content of 0.31% by weight, and a density of 1.4019 g /
The content of cm ³ , fines, etc. was about 5750 ppm. Also, the peak on the highest temperature side of the fine peak temperature
The temperature was 279 ° C. Also, during the fine, brown,
There is a considerable amount of rodent-colored foreign matter, and according to X-ray microanalyzer analysis, calcium,
A metal such as silicon was detected. These PETs were evaluated using a molded plate and a biaxially stretched molded bottle. The haze of the formed plate is 34.9%, the Tc1 of the formed plate is 142.
° C., the density of the mouth part is very high and 1.398g / cm ^3, the foreign matter of the hollow molded body is a "× (very exists many)", was free commercial value. In the leak test of the contents, leakage of the contents was found. The body haze of the obtained bottle was very poor at 15.2%, and the portion where foreign matter was present had a problem that the foreign matter became the core and the thickness was abnormally thick.

(Comparative Example 2) Sheet molding evaluation was performed on PET after 6 months of continuous production manufactured in the same manner as in Comparative Example 1. In addition, melt polycondensation PE to be added to the solid phase polymerization step
The content of fines etc. of T (6th month of continuous production) is about 15
00 ppm, solid-state polymerization P to be added to the sheet forming process
The fine content of ET was about 7500 ppm, and the intrinsic viscosity was 0.73 deciliter / gram. A sheet was produced in the same manner as in Example 4, but the back pressure suddenly increased in one day's production, the wire net was broken, and normal production was impossible. In addition, the obtained sheets of foreign matter were innumerable and had no commercial value.

[0171]

[Table 1]

[0172]

EFFECTS OF THE INVENTION According to the present invention, a hollow molded article or the like which contains almost no foreign matter and is excellent in transparency is provided, and the polyester is less likely to cause mold stains during molding of the molded article, or during film formation. It is possible to advantageously obtain a polyester having less filter clogging during spinning and improved operability.

[Brief description of drawings]

FIG. 1 is a schematic view of a water treatment device used in an example.

[Explanation of symbols]

1 Raw Material Chip Supply Port 2 Overflow Discharge Port 3 Polyester Chip and Treated Water Discharge Port 4 Drainer 5 Fine Removal Device 6 Piping 7 Recycled Water or / and Ion Exchange Water Inlet 8 Adsorption Tower 9 Ions Exchange water inlet

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Kazuki Yamauchi             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) 4J002 BB00X CB00Z CF06W CL00Y                       GG01 GG02 GN00                 4J029 AA03 AC01 AC02 AD01 AD10                       AE01 AE02 AE03 BA03 CB06A                       KD17 KE05 KE12 KE15 KH05

Claims (10)

[Claims] 1. A sodium content (N), a magnesium content (M), a silicon content (S) and a calcium content (C) are at least one of the following (1) to (4): A method for producing a polyester, which comprises solid-phase polymerizing a molten polycondensation polyester prepolymer which is made into chips while cooling with cooling water satisfying the above conditions. N ≤ 1.0 (ppm) (1) M ≤ 0.5 (ppm) (2) S ≤ 2.0 (ppm) (3) C ≤ 1.0 (ppm) (4) 2. The method for producing a polyester according to claim 1, wherein at least water treated by an ion exchange device is used as cooling water in the chipping step. 3. The fine and / or film-like material is removed from the melt polycondensed polyester prepolymer and / or the polyester after solid-phase polymerization, according to claim 1 or 2. Method for producing polyester. 4. The content of any one of the fine content, the film-like material content, or the total content of the fine content and the film-like material content of the polyester before the solid phase polymerization is 500 ppm or less. The method for producing a polyester according to any one of claims 1 to 3, wherein: 5. The method for producing a polyester according to claim 1, wherein the solid content polyester has a fine content of 5000 ppm or less. 6. A polyester comprising ethylene terephthalate as a main repeating unit and having an intrinsic viscosity of 0.55 to 0.55.
It is 2.0 deciliter / gram polyester, The manufacturing method of the polyester in any one of Claims 1-5 characterized by the above-mentioned. 7. A polyester comprising ethylene terephthalate as a main repeating unit and having an intrinsic viscosity of 0.67 to.
1.5 deciliter / gram, acetaldehyde content of 10 ppm or less, cyclic trimer content of 0.5% by weight or less, fine content of 500 ppm or less, haze of a molded plate obtained by injection molding is 15% or less. And the crystallization temperature (Tc1) at the time of temperature rise of the molded plate measured by DSC is 150.
The method for producing a polyester according to any one of claims 1 to 4, wherein the polyester is in the range of 175C to 175C. 8. The peak temperature of the highest melting peak temperature of fine contained in the solid-phase polymerized polyester is 2
It is 65 degrees C or less, The manufacturing method of the polyester in any one of Claims 1-7 characterized by the above-mentioned. 9. The method for producing a polyester according to claim 1, wherein the solid-phase-polymerized polyester is contact-treated with water. 10. The solid-phase-polymerized polyester is blended with at least one resin selected from the group consisting of a polyolefin resin, a polyamide resin, and a polyacetal resin, according to any one of claims 1 to 9. A method for producing the described polyester.