JPH11236440A - Production of polyester, polyester and polyester molding - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyester with slight deterioration despite containing triiron tetraoxide therein, excellent in near infrared ray absorption efficiency and color tone, and to obtain a molding from the polyester. SOLUTION: This method for producing a polyester comprises an esterification process where an esterification is performed between an aromatic dicarboxylic acid or an ester-forming derivative thereof and an aliphatic diol, a melt polymerization process where a melt polymerization of the esterified product obtained above is performed in the presence of a polycondensation catalyst, and if necessary, a solid phase polymerization process where the polycondensation reaction product obtained above is heated to a temperature lower than its melting point in an inert atmosphere; wherein in such stage(s) as to be <=1,000 equivalents/ton in the acid value of the product(s), triiron tetroxide is added at 1-100 ppm to the product(s). The polyester thus obtained has an intrinsic viscosity of 0.4-1.5 dL/g and hue (a) - number of <=1.0.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a method for producing a polyester containing triiron tetroxide, a polyester and a molded product thereof. More specifically, the present invention relates to a method for producing a polyester, in which triiron tetroxide is added at a specific stage, a polyester and a molded product thereof. Since the polyester obtained by the method of the present invention is excellent in near-infrared absorption efficiency and color tone, it can be widely used as a stretch blow container or the like.

[0002]

2. Description of the Related Art Iron trioxide (Fe ₃ O ₄ ) has good electromagnetic wave absorption, coloring, antioxidation and magnetic properties, and has conventionally been mixed or dispersed in a thermoplastic resin by melt-kneading. It is known that surface coating imparts its performance to molded products such as resin and containers and films made of the resin. On the other hand, polyesters such as polyethylene terephthalate (hereinafter sometimes abbreviated as “PET”) have excellent mechanical strength, chemical stability, gas barrier properties, hygiene properties, etc., and are relatively inexpensive and lightweight. It is widely used as various food and beverage packaging containers.

In the production of these packaging containers, there is a method in which a preform is first formed at the time of molding, the preform is softened by reheating, and then reshaped into a desired shape. For example, in manufacturing a stretch blow container, first, a bottomed tubular preform is manufactured by injection molding, and the preform is usually reheated and softened by a near-infrared heater and then blown. It is manufactured in close contact with a mold having a predetermined shape. However, such a method for producing a packaging material has a problem that productivity is poor because it takes time to reheat the preform. For such a problem, triiron tetroxide excellent in electromagnetic wave absorption is compounded in polyester,
A method of increasing the near-infrared absorption efficiency to shorten the reheating time and increase the productivity can be considered.

[0004]

However, triiron tetroxide is very liable to be oxidized. Therefore, when mixing and dispersing in a polymer, melt kneading is performed by using a kneading extruder or an injection molding machine by dry blending. For polymers that need to be melt-kneaded at a relatively high temperature (about 200 ° C. or higher), such as polyester, especially polyethylene terephthalate (hereinafter sometimes abbreviated as “PET”), oxidized during melt-kneading to obtain Iron (Fe ₂ O ₃ ) has a problem of being deteriorated and its electromagnetic wave absorbing property being lost, and the color tone is also black, but it becomes reddish. Also, when mixing and dispersing in a raw material before polymerization, the polyester has a similar problem because the polymerization temperature is high.
Therefore, polyesters containing triiron tetroxide, having excellent near-infrared absorption efficiency and little redness have not been known. The present invention solves the above-mentioned problems, and a method for producing a polyester capable of suppressing the deterioration thereof even though ferric oxide is added during polymerization, and a near-infrared absorption efficiency obtained by the method. It is an object to provide a polyester excellent in color and color tone and a molded article thereof.

[0005]

Means for Solving the Problems As a result of intensive studies in view of such circumstances, the present inventors have solved the above-mentioned problems by adding iron tetroxide at a specific stage after the esterification step. We have found that we have completed the present invention.

That is, the gist of the present invention is as follows. An esterification step of esterifying an aromatic dicarboxylic acid or an ester-forming derivative thereof and an aliphatic diol,
Melt polymerization of the esterified product obtained in the esterification step in the presence of a polycondensation catalyst and, if necessary, the temperature of the polycondensation reaction product obtained in the melt polymerization step below its melting point under an inert atmosphere. In a method for producing a polyester comprising a solid phase polymerization step of heating to a temperature of 1 to 100 ppm of iron tetroxide, 1 to 100 ppm is added to the product at a stage where the acid value of the product is 1,000 equivalents / ton or less after the esterification step. A method for producing a polyester, characterized by having an intrinsic viscosity of 0.4 to 1.5 dl / g and a hue a value of 1.0 or less, obtained by the production method described in section 2.1. 3. A pre-injection molded article for a stretch blow container, which is obtained by injection-molding the polyester described in 3.2. Hereinafter, the present invention will be described in detail.

[0007]

DETAILED DESCRIPTION OF THE INVENTION (1) Polyester In the present invention, a polyester is obtained by a melt polycondensation reaction between an aromatic dicarboxylic acid or an ester-forming derivative thereof and an aliphatic diol in the presence of a polycondensation catalyst. Say.

As the aromatic dicarboxylic acid component, terephthalic acid or 2,6-naphthalenedicarboxylic acid is preferred, each of which is preferably used alone, preferably 90 mol% of the total acid component.
The content is more preferably at least 95 mol%, further preferably at least 97 mol%. Examples of dicarboxylic acid components other than terephthalic acid and 2,6-naphthalenedicarboxylic acid include isophthalic acid, orthophthalic acid, cyclohexanedicarboxylic acid, dibromoisophthalic acid, sodium sulfoisophthalate, biphenyldicarboxylic acid, biphenyletherdicarboxylic acid, and biphenylsulfonedicarboxylic acid. Aromatic dicarboxylic acids such as acid, biphenyl ketone dicarboxylic acid, biphenoxyethane dicarboxylic acid, phenylenedioxy dicarboxylic acid, adipic acid, sebacic acid, succinic acid, glutaric acid, piperic acid, suberic acid, azelaic acid, undecane dicarboxylic acid And an aliphatic dicarboxylic acid such as dodecanedicarboxylic acid. Isophthalic acid is particularly preferred, and the amount thereof is preferably 3 mol% or less. In addition, the ester-forming derivative of the aromatic dicarboxylic acid means, for example, a lower alkyl ester such as a methyl ester or an ethyl ester thereof.

[0009] The aliphatic glycol component is preferably ethylene glycol, preferably 90 mol% or more, more preferably 95 mol% or more of the total diol component. As diol components other than ethylene glycol, for example, butylene glycol, trimethylene glycol, tetramethylene glycol, pentamethylene glycol, hexamethylene glycol, octamethylene glycol, decamethylene glycol, propylene glycol, diethylene glycol, polyethylene glycol,
Aliphatic glycols such as polyoxytetramethylene glycol, 1,4-cyclohexanedimethanol, 2,5-
Alicyclic glycols such as norbornene dimethanol, neopentyl glycol, 2-butyl-2-ethyl-1,3
Branched aliphatic glycols such as propanediol; aromatic glycols such as xylylene glycol; ethylene oxide adducts and propylene oxide adducts of 2,2-bis (4-hydroxyphenyl) propane; and diethylene glycol is particularly preferable. The amount is preferably 5 mol% or less, more preferably 1 to 3 mol%. In this case, diethylene glycol may be contained as a by-product generated by dehydration and dimerization of ethylene glycol during the polymerization of the polyester and incorporated into the polyester main chain, or may be added in advance during the polymerization. You may.

Further, in the polyester of the present invention,
The component may contain a small amount of a monofunctional component or a polyfunctional component without departing from the effects of the present invention. For example, monofunctional components such as stearic acid and benzoic acid, trimellitic acid, trimesic acid, pyromellitic acid, tricarballylic acid, gallic acid, trimethylolpropane, triethylolethane, pentaerythritol, glycerin, tetrakis [methylene-3- ( 3 ', 5'-di-t-butyl-4'
-Hydroxyphenyl) propionate] trifunctional or more polyfunctional components such as methane.

(2) Iron tetroxide In the production method of the present invention, the weight of the iron tetroxide to be added is
It is preferably in the range of 1 to 100 ppm, more preferably 10 to 50 pp, based on the obtained polymer weight.
m, more preferably 20 to 40 ppm. Further, the BET average particle diameter of the ferric oxide is preferably 0.01 to 10%.
μm, preferably 0.05 to 1 μm, more preferably 0.1 to 0.5 μm. Further, the pH of triiron tetroxide is preferably from 8 to 11, and the bulk specific gravity of the triiron tetroxide is preferably from 0.6 to 1.0 g / ml.

(3) Method for Producing Polyester The production method of the present invention is for producing a polyester by preparing a raw material slurry, esterifying, melt-polymerizing, and, if necessary, subsequent solid-phase polymerization. For the esterification, for example, terephthalic acid, ethylene glycol or another copolymerizable monomer is used to directly carry out the esterification reaction under pressure to obtain a low-molecular weight polyester. Further, a low-molecular weight polyester may be obtained by performing a transesterification reaction using an ester derivative of a dicarboxylic acid, for example, dimethyl terephthalate as a raw material instead of the dicarboxylic acid.
In the case of melt polymerization, a low-molecular weight polyester obtained by esterification is further heated in the presence of a catalyst and gradually reduced in pressure to undergo a polycondensation reaction. For solid-phase polymerization, a polyester obtained by melt polymerization is drawn out from a reaction tank in a strand shape, cut into granules (chips), dried and crystallized, and subsequently dried at a temperature below the melting point under reduced pressure or The polycondensation reaction is performed under an inert gas stream.
Each of these manufacturing steps may be a batch type or a continuous type.

In the esterification step, when a direct esterification reaction is performed, the temperature of the esterification reaction is, for example, when terephthalic acid and ethylene glycol are used as raw materials.
Usually 240 to 280 ° C, preferably 250 to 270 ° C,
Pressure is 0-3 kg / cm ² G, preferably 0-2 kg / cm ² G
Heating and stirring are performed under a pressure of cm ² G for 1 to 10 hours. Thus, the normal acid value is 1200-300 equivalents /
Ton (hereinafter abbreviated as eq / ton) esterified product is obtained.

In the melt polymerization step, the temperature of the melt polymerization is usually from 260 to 290 ° C., preferably from 26 to 290 ° C. when terephthalic acid and ethylene glycol are used as raw materials.
5 to 285 [deg.] C., and the pressure is gradually reduced from normal pressure, and finally is usually 10 to 0.1 torr, preferably 5 to 0.1 torr.
0.5 Torr. Due to the melt polymerization, the acid value of the reactant further decreases.

In the production method of the present invention, the above-mentioned ferric tetroxide is converted into an acid value of 1000 eq / ton or less, more preferably 800 eq / ton, in the above production step, preferably after the esterification step. Ton is added at the following stage. More preferably, after the transesterification step, it is added immediately before or at the initial stage of the polycondensation reaction, at a stage where the acid value is 500 eq / ton or less. If the addition time is other than the above, the effects of the present invention will not be exhibited. For example, if added at the beginning of the esterification step with a very high acid value or added in the form of being mixed with the raw material monomer at the time of preparing the raw material slurry, the ferric oxide changes during the polymerization, resulting in The near infrared absorption efficiency of the polyester obtained is low, and the color tone is reddish.

In the direct esterification reaction, transesterification reaction and melt polymerization reaction in the production process of the present invention, necessary amounts of an esterification catalyst, a transesterification catalyst, a polycondensation catalyst, a stabilizer and the like are used. Is also good. The esterification catalyst may not be added because terephthalic acid serves as an autocatalyst of the esterification reaction, but a polycondensation catalyst described later may be used, or a small amount of an inorganic acid or the like may be used. Examples of the transesterification catalyst include alkali metal salts such as sodium and lithium, alkaline earth metal salts such as magnesium and calcium, and metal compounds such as zinc and manganese. The proportion of these catalysts used is
The amount of the metal in the catalyst is usually used in the range of 5 to 2000 ppm.

As the polycondensation catalyst, a compound soluble in the reaction system such as a germanium compound, an antimony compound, a titanium compound, a cobalt compound, a tin compound or the like may be used alone or in combination, but it is preferable to use an antimony compound. It is preferable in terms of productivity. Examples of the antimony compound include antimony trioxide, antimony acetate, antimony trisethylene glycoloxide, and the like. Germanium compounds include germanium dioxide, and titanium compounds include tetra-n-butoxytitanium. Examples of the stabilizer include phosphates such as trimethyl phosphate, triethyl phosphate, tri-n-butyl phosphate, trioctyl phosphate, triphenyl phosphate, tricresyl phosphate, triphenyl phosphite, trisdodecyl phosphite, and trisnonyl decyl. Phosphites such as phosphite, methyl acid phosphate, ethyl acid phosphate, isopropyl acid phosphate, butyl acid phosphate, dibutyl phosphate, monobutyl phosphate, acid phosphate such as dioctyl phosphate,
It is preferable to use phosphorus compounds such as phosphoric acid, phosphorous acid, hypophosphorous acid, and polyphosphoric acid. The proportion of these catalysts or stabilizers used is usually 5 to 2000 pp as the weight of the metal in the catalyst in the case of a catalyst, based on the total amount of the polymerization raw materials.
m. In the case of a stabilizer, the weight of phosphorus atoms in the stabilizer is usually 10 to 1000 pp.
m. These catalysts and stabilizers can be supplied at the time of preparing the raw material slurry, at any stage of the esterification reaction or transesterification reaction, and further, at the beginning of the polycondensation reaction step.

The polyester thus obtained by the melt polymerization is usually melt-extruded into a strand shape, extracted from the reactor, and then granulated by a cutter.
Is cut into In this case, the intrinsic viscosity of the obtained melt-polymerized chips is preferably from 0.4 to 1.5 dl / g, more preferably from 0.4 to 0.7 dl / g. In this case, the hue a value of the melt polymerization chip is usually 1.0 or less. When the intrinsic viscosity is outside the above range,
Extraction from the reactor and chipping with a cutter are difficult, and when the intrinsic viscosity is high, alteration of triiron tetroxide tends to occur, and the near infrared absorption efficiency and color tone tend to be impaired.

Further, it is preferable that the polyester granules obtained by melt polymerization are subjected to a heat treatment to increase the degree of polymerization by crystallization and solid phase polymerization. In this case, it is preferable that a melt polymerization chip having an intrinsic viscosity of 0.4 to 0.7 dl / g is solid-phase polymerized to have an intrinsic viscosity of 0.5 to 1.5 dl / g. This is because the solid-state polymerization is performed at a lower temperature than the melt polymerization, so that the deterioration of triiron tetroxide hardly proceeds, and the obtained polyester is advantageous in terms of near-infrared absorption efficiency and color tone. At the same time, the amount of acetaldehyde, oligomer, and the like can be reduced.

This heat treatment is usually carried out by drying nitrogen,
After crystallizing the surface of the polyester granules at a temperature of 60 to 180 ° C. under an inert gas such as argon or carbon dioxide or under steam or an inert gas containing steam, the resin adheres under reduced pressure or under an inert gas. It is carried out at a temperature just below the temperature or 80 ° C. lower and within several tens of hours. In the solid phase polymerization, it is preferable to carry out the polyester particles while flowing them by an appropriate method such as a tumbling method or a gas fluidized bed method so that the polyester particles do not adhere to each other. Also,
In this polyester, if necessary, other than triiron tetroxide, conventionally known nucleating agent, inorganic filler material, lubricant, slip agent, antiblocking agent, stabilizer, antistatic agent, antifogging agent, Various additives such as pigments may be appropriately added as long as the effects of the present invention are not impaired.

(4) Pre-Injection Molded Article and Stretch Blow Container The polyester obtained by the production method of the present invention is used to prepare, for example, a stretch blow molded article by a method generally used for polyethylene terephthalate. It is possible to obtain a preform and a stretch-formed product comprising the preform. For example, it is suitable for a preform for stretch blow molding and a stretch blow hollow container made of the preform. It is also suitable for a sheet-shaped preform and a drawn container made of the same.

For example, in manufacturing a stretch blow hollow container, first, a tubular preform having a bottom is manufactured by injection molding, and the preform is reheated to be softened and then blown to a predetermined temperature. It is manufactured in close contact with a shaped mold. In this case, the resin temperature during injection molding is usually 200 to 350 ° C, preferably 250 to 320 ° C, and the mold temperature is usually 0 to 30 ° C.
It is. The reheating temperature of the preform is usually 70 to 1
The temperature is 30 ° C., preferably 80 to 125 ° C., and the blow mold temperature is usually room temperature to 200 ° C., preferably 40 to 1 ° C.
80 ° C. range. In this case, a near-infrared irradiation furnace is usually used for reheating the preform, and for example, a quartz heater is used. Further, for the purpose of improving heat resistance and the like, the obtained hollow molded body may be subjected to heat setting by a conventionally known method, and a blow mold temperature when applying the heat setting is usually 70 to 200 ° C., preferably. Is 90-180 ° C,
It is more preferably in the range of 120 to 160 ° C.

[0023]

EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to these examples unless it exceeds the gist. In addition,
Various measurement methods and evaluation methods used in Examples and Comparative Examples are as follows.

Analysis of Polyester Composition Polyester is dissolved in deuterated trifluoroacetic acid at room temperature to prepare a 3% by weight solution. JNM-EX2 manufactured by JEOL
¹ H-NMR of this solution was measured with a type 70 nuclear magnetic resonance apparatus, each peak was assigned, and the peak was calculated from the integral ratio.

Measurement of acid value After pulverizing the polyester, it was heated at 140 ° C. in a hot air drier.
Dry for 15 minutes and cool to room temperature in a desiccator.
0.1 g of the ground sample was precisely weighed, collected in a test tube, added with 3 ml of benzyl alcohol, and dissolved by heating and stirring at 195 ° C. for 3 minutes while blowing dry nitrogen gas. Thereafter, 5 ml of chloroform was gradually added, and the mixture was cooled to room temperature. One or two drops of phenol red indicator is added to this solution, and 0.1N NaOH is added while stirring while blowing dry nitrogen gas.
Titration was performed with a benzyl alcohol solution, and when the color changed from yellow to red, the end point was determined. In addition, the above operation was performed without a polyester sample as a blank, and the acid value was calculated by the following formula.

[0026]

(Equation 1) A: amount of 0.1N NaOH required for titration (μL) B: blank titer (μL) W: amount of polyester sample (g) f: titer of 0.1N NaOH benzyl alcohol

The benzyl alcohol titer was measured as follows. That is, 5 ml of methanol was placed in a test tube, 1-2 drops of an ethanol solution of phenol red was added as an indicator, and the color change point was measured with 0.4 ml of a 0.1 N NaOH benzyl alcohol solution. Next, 0.2 ml of a 0.1 N HCl aqueous solution having a known titer was taken as a standard solution, and the solution was again measured with a 0.1 N NaOH benzyl alcohol solution until the color change point. The above operation was performed while blowing dry nitrogen gas. Then, according to the following formula, 0.
The 1N NaOH benzyl alcohol solution was titered.

[0028]

(Equation 2)

The above titration operation was performed three times, and the average value was adopted. Intrinsic viscosity After 5 g of polyester is freeze-pulverized, 0.2 g of the pulverized product is used as a sample. The same applies to the case where the intrinsic viscosity of a molded plate described later is measured. This was added to a mixed solvent of phenol / tetrachloroethane (weight ratio 1/1) at a concentration of c = 1 g / dl.
Dissolve in. The dissolution conditions in this case are, at 100 ° C. for 20 minutes,
In the case of solid-phase polymerized polyester chips, 2
0 minutes. The relative viscosity η _rel of this solution with the stock solution is measured at a temperature of 30 ° C. using an Ubbelohde capillary viscometer. Assuming that η _sp = η _rel −1, the ratio η of this η _sp to the concentration c
_{Find sp} / c. This operation is performed at a density c = 0.5, 0.2,
This is performed for 0.1 dl / g, and each η _sp / c is obtained, and η _sp / c (dl / g) at c = 0 is extrapolated from these values. The value obtained by extrapolation is the intrinsic viscosity η (dl / g).

Measurement of Hue a Value The hue of the polyester chip was measured using Z-100 manufactured by Nippon Denshoku Co., Ltd.
Hue was measured using a 1DD colorimeter. The lower the a-value, the less reddish and the better the hue.

Evaluation of Bottle Molding (Evaluation of Preheating Efficiency and Transparency) The polyester was sufficiently dried, and a resin temperature of 280 ° C., a back pressure, an injection pressure and a holding pressure were measured using an injection molding machine IS-16B manufactured by Toshiba Machine Co., Ltd. 5, 100, 50 kg / cm ² respectively
A test tube preform having a height of 165 mm, a pipe outer diameter of 29.0 mm, an average wall thickness of 3.7 mm and a basis weight of 60 g was injection-molded at a mold temperature of 20 ° C. and a molding cycle of about 40 seconds. The preform was heated in a near-infrared irradiation furnace consisting of a quartz heater for 55 seconds and then left at room temperature for 25 seconds to relax the temperature distribution inside the preform. Immediately thereafter, it is sandwiched in a mold having a predetermined shape adjusted to 20 ° C., and blown at a blow pressure of 20 kg / cm ² , and the average thickness of the body is 350 mm.
A 1.5 μm bottle with a volume of 1.5 μm was obtained.

The haze at a certain point on the body of the obtained bottle was measured with an NDH-300A haze meter manufactured by Nippon Denshoku Co., Ltd. High haze means low preheating efficiency,
Insufficient preheating means cold stretching and cloudy bottles. Conversely, a low haze means that the preheating efficiency is high, the preheating is sufficient, and the bottle has good transparency. The redness of the obtained bottle was visually evaluated. In Table 1 described below, the case where the redness of the hollow container is small and good is indicated by “○”,
In particular, the case of good was indicated by “◎”, and the case where the hollow container was reddish and defective was indicated by “x”.

Example 1 Polyester was produced by the following operation using a batch polymerization apparatus having one stage of a slurry tank, one stage of an esterification tank, and one stage of a melt polymerization tank. In the slurry tank, terephthalic acid 2
54 kg (1533 mol), 4.7 kg of isophthalic acid
(28 mol), 114 kg of ethylene glycol (183
6 moles) of slurry was prepared and 3.8 kg (15
Mol) of bis (2-hydroxyethyl) terephthalate to prepare a raw material slurry. The raw material slurry was sequentially supplied to the esterification tank maintained at 260 ° C. over 4 hours. After the supply was completed, the esterification reaction was further performed for 1 hour, and the esterified product was transferred to the melt polymerization tank. The acid value of this esterified product was 450 eq / t. Subsequently, from a pipe connected to the melt polymerization tank, orthophosphoric acid was first added so as to be 33 ppm as a phosphorus element based on the weight of the polymer after polymerization, and 10 minutes later, cobalt acetate was added as an auxiliary agent after polymerization. It is added so that it becomes 10 ppm as a cobalt element with respect to the polymer weight, and immediately after that, antimony trioxide is added so that it becomes 210 ppm as an antimony element with respect to the polymer weight after polymerization. Industrial Co., Ltd. HR-370H, BET average particle size 0.17 μm, pH 9-10, bulk specific gravity 0.70 g /
ml) as an ethylene glycol slurry and 30 ppm as triiron tetroxide based on the weight of the polymer after polymerization.
Was added so that Subsequently, the temperature in the system was reduced from 260 ° C to 2
The temperature was raised to 80 ° C in 1 hour and 20 minutes,
The pressure was reduced in 0 minutes, and the pressure was maintained at 1 mmHg to perform a melt polymerization reaction. After conducting the reaction for the required time, the produced polymer is drawn out in a strand form from a discharge port provided at the bottom of the polycondensation tank, cooled with water, cut into chips, and melted to an intrinsic viscosity of about 270 kg with an intrinsic viscosity of 0.62 dl / g. A polymerized polyester was produced. The esterification reaction and the melt polymerization reaction proceeded smoothly. Table 1 shows the analytical evaluation results of the obtained polyester. This polyester is less reddish, has less deterioration of ferric oxide, and is excellent in color tone.

Example 2 A melt-polymerized polyester was produced in the same manner as in Example 1, except that the melt polymerization time was extended and the intrinsic viscosity was set to 0.78. Esterification and melt polymerization reactions proceeded smoothly. Table 1 shows the analytical evaluation results of the obtained polyester. This polyester is less reddish, has less deterioration of ferric oxide, and is excellent in color tone.

Example 3 The melt-polymerized polyester obtained in Example 1 was crystallized at 160 ° C. with a stirring crystallization machine (Bepex company formula).
The mixture was transferred to a stationary solid-state polymerization tower, dried at about 160 ° C. for 3 hours under a nitrogen flow of 20 L / kg · hr, solid-phase polymerized at 205 ° C. for a predetermined time, and had an intrinsic viscosity of 0.82 dl / g (see Table 1 for details). ) Was produced. Table 1 shows the analytical evaluation results of the obtained polyester. This polyester is less reddish than that of Example 2, has less deterioration of triiron tetroxide, and is excellent in color tone.

Comparative Example 1 A melt-polymerized polyester having an intrinsic viscosity of 0.62 dl / g was produced in the same manner as in Example 1 except that the ethylene glycol slurry of triiron tetroxide was added to the raw material slurry tank. did. Esterification and melt polymerization reactions proceeded smoothly. Table 1 shows the analytical evaluation results of the obtained polyester. This polyester has a strong reddish color and has a poor color tone due to the deterioration of ferric oxide.

Examples 4 and 5 and Comparative Example 2 Using the polyesters obtained in Examples 2 and 3 and Comparative Example 1, respectively, a bottle molding evaluation was performed. Table-Evaluation results
It is shown in FIG. Table 1 shows the analytical evaluation results of the obtained bottles.

[0038]

[Table 1]

[0039]

According to the production method of the present invention, it is possible to obtain a polyester excellent in near-infrared absorption efficiency and color tone, which contains little amount of iron tetroxide in spite of containing iron trioxide, and a molded article thereof. Therefore, the production method of the present invention is suitable for producing polyester used as various molded articles, various packaging materials, and containers, and has high industrial value.

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[Procedure amendment]

[Submission date] April 14, 1998

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Claim 4

[Correction method] Change

[Correction contents]

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction contents]

(3) Method for Producing Polyester The production method of the present invention is for producing a polyester by preparing a raw material slurry, esterifying, melt-polymerizing, and, if necessary, subsequent solid-phase polymerization. For the esterification, for example, terephthalic acid, ethylene glycol or another copolymerizable monomer is used to directly carry out the esterification reaction under pressure to obtain a low-molecular weight polyester. Alternatively, a low-molecular weight polyester may be obtained by performing a transesterification reaction using an ester- forming derivative of a dicarboxylic acid, for example, dimethyl terephthalate as a raw material instead of the dicarboxylic acid. In the case of melt polymerization, a low-molecular weight polyester obtained by esterification is further heated in the presence of a catalyst and gradually reduced in pressure to undergo a polycondensation reaction. For solid-phase polymerization, polyester obtained by melt polymerization is drawn out from the reaction tank in the form of a strand, cut and granulated (chips).
After that, this is dried and crystallized, and subsequently subjected to a polycondensation reaction at a temperature not higher than the melting point under reduced pressure or an inert gas stream. Each of these manufacturing steps may be a batch type or a continuous type.

[Procedure amendment 3]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction contents]

This heat treatment is usually carried out by drying nitrogen,
After crystallizing the surface of the polyester granules at a temperature of 60 to 180 ° C. under an inert gas such as argon or carbon dioxide or under steam or an inert gas containing steam, the resin adheres under reduced pressure or under an inert gas. It is carried out at a temperature just below the temperature or 80 ° C. lower and within several tens of hours. In the solid phase polymerization, it is preferable to carry out the polyester particles while flowing them by an appropriate method such as a tumbling method or a gas fluidized bed method so that the polyester particles do not adhere to each other. Also,
In this polyester, if necessary, other than triiron tetroxide, conventionally known nucleating agent, inorganic filler material, lubricant, slip agent, antiblocking agent, stabilizer, antistatic agent, antifogging agent, Various additives such as pigments, dispersants, and the like may be appropriately blended within a range that does not impair the effects of the present invention.

[Procedure amendment 4]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction contents]

The bottle molding evaluation (preliminary heating efficiency and evaluation of transparency) polyester was sufficiently dried using a Toshiba Machine Co., Ltd. injection molding machine IS- 60 B, a resin temperature 280 ° C., back pressure, injection pressure, holding pressure 5, 100, 50 kg / cm ²
A test tube preform having a height of 165 mm, a pipe outer diameter of 29.0 mm, an average wall thickness of 3.7 mm and a basis weight of 60 g was injection-molded at a mold temperature of 20 ° C. and a molding cycle of about 40 seconds. The preform was heated in a near-infrared irradiation furnace consisting of a quartz heater for 55 seconds and then left at room temperature for 25 seconds to relax the temperature distribution inside the preform. Immediately thereafter, it is sandwiched in a mold having a predetermined shape adjusted to 20 ° C., and blown at a blow pressure of 20 kg / cm ² , and the average thickness of the body is 350 mm.
A 1.5 μm bottle with a volume of 1.5 μm was obtained.

[Procedure amendment 5]

[Document name to be amended] Statement

[Correction target item name] 0038

[Correction method] Change

[Correction contents]

[0038]

[Table 1]

Claims (6)

[Claims] 1. An esterification step of esterifying an aromatic dicarboxylic acid or an ester-forming derivative thereof with an aliphatic diol, and melt polymerization of an ester obtained in the esterification step in the presence of a polycondensation catalyst. In the method for producing a polyester comprising a solid-phase polymerization step of heating the polycondensation reaction product obtained in the melt polymerization step to a temperature not higher than its melting point under an inert atmosphere, if necessary, the production after the esterification step, A method for producing a polyester, characterized in that 1 to 100 ppm of iron tetroxide is added to the product at a stage where the acid value of the product is 1,000 equivalents / ton or less. 2. The ferric oxide having a BET average particle size of 0.0
1 to 10 μm, pH 8 to 11 and bulk specific gravity 0.6 to 1.
The method for producing a polyester according to claim 1, wherein the amount is 0 (g / ml). 3. An intrinsic viscosity of 0.4 to 1.5 dl / g and a hue a obtained by the production method according to claim 1 or 2.
A polyester having a value of 1.0 or less. 4. The polyester according to claim 3, wherein the polyester has an intrinsic viscosity of 0.5 to 1.0 dl / g and a hue a value of 0.5 dl / g or less. 5. A pre-injection molded article for a stretch blow container obtained by injection-molding the polyester according to claim 3 or 4. 6. A stretch blow container obtained by stretching and blowing the pre-injection molded article for a stretch blow container according to claim 5.