JPH11209467A - Method for producing modified polyester resin - Google Patents

Abstract

(57) [Problem] To provide a method for producing a polyester resin in which the crystallization rate is controlled without impairing the transparency. SOLUTION: In a step of forming a polyester resin chip after melt polymerization obtained by polymerizing a dicarboxylic acid component mainly containing terephthalic acid or a lower alkyl ester thereof and a glycol component mainly containing ethylene glycol, a strand or Water containing powder of another crystalline thermoplastic resin is used as cooling water for chips.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a modified polyester resin. More specifically, the present invention relates to a method for modifying a polyester resin by bringing it into contact with another crystalline thermoplastic resin before the solid-state polymerization step. The modified polyester resin produced according to the present invention is useful for bottles, film sheets and the like because the crystallization rate is controlled without impairing the transparency.

[0002]

2. Description of the Related Art Conventionally, glass has been widely used as a container for beverages such as fruit juice, tea and mineral water, alcoholic beverages such as sake and shochu, seasonings, oils, detergents and cosmetics. It has drawbacks in that it is easy to handle and break. Conversion from glass containers to plastic containers is in progress to eliminate these disadvantages. Biaxially oriented containers made of a resin mainly composed of polyethylene terephthalate (hereinafter abbreviated as PET) in the fields of fruit juice, tea, carbonated beverages and other beverages, seasonings, detergents, cosmetics, etc., which require transparency, are particularly required. Has been adopted. In recent years, when a small-capacity container is manufactured, the preform is injection-molded to improve productivity, and when the preform is blow-molded, the bottle body density is increased very quickly in producing a heat-resistant bottle. It is manufactured by setting the mold temperature to a high temperature of 120 to 180 ° C. and heat fixing the bottle body. Further, in the case of a content liquid that requires hot filling such as a fruit juice beverage, a method of crystallizing the preform or the molded bottle by heat-treating the plug portion (Japanese Patent Application Laid-Open No. 55-79237; 58-1
No. 10221).

[0003] The known method as described above, namely, the plug part,
The method of improving the heat resistance by heat treatment of the shoulder is that the time for crystallization treatment, the temperature greatly affects the productivity, the polyester resin can be processed at a low temperature and in a short time, the crystallization speed is fast. preferable. On the other hand, the body is required to be transparent even when subjected to a heat treatment at the time of molding so as not to deteriorate the color tone of the filler, and the plug and the body need contradictory characteristics. Generally, polyester resins with excellent transparency are slow in crystallization, so sacrifice transparency and improve the crystallization speed by lowering the intrinsic viscosity of the resin, or sacrificing productivity, There is only a method of performing the heat treatment, and it is difficult to satisfy both characteristics.

[0004] In order to simultaneously improve the crystallization rate and ensure transparency, various methods of modifying a polyester resin by contacting it with another crystalline thermoplastic resin have been proposed from the resin side. Have been. For example, Japanese Patent Application Laid-Open No. 9-71637 proposes a method in which a chip of a polyester resin after solid-phase polymerization is brought into contact with a polyethylene member under flow conditions.

[0005]

However, since the chips obtained above are generally brought into contact with a thermoplastic crystalline resin member such as a polyethylene member after solid-phase polymerization, the polyester resin after solid-phase polymerization is generally used. And it was hard to say that the crystallization rate was modified after the melt polymerization. The present invention relates to a modified polyester resin in which the crystallization rate can be controlled by contacting the polyester resin with another crystalline thermoplastic resin before solid-phase polymerization without impairing its transparency. It is intended to provide a manufacturing method.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies in order to solve the above-mentioned problems. As a result, in the step of forming a polyester resin into chips after melt polymerization, crystalline thermoplastic water is added to cooling water for chips. By using the water to which the resin is added, by bringing the polyester resin into contact with the crystalline thermoplastic resin, the time required for crystallization in the crystallization step before solid-phase polymerization is reduced, and furthermore, after solid-phase polymerization, However, they have found that the crystallization rate can be improved continuously and without impairing the transparency, and have completed the present invention.

That is, the gist of the present invention is to provide a melt-polymerized polyester resin obtained by polymerizing a dicarboxylic acid component having terephthalic acid or a lower alkyl ester thereof as a main component and a glycol component having ethylene glycol as a main component. A method for producing a modified polyester resin, wherein in the chipping step, water containing powder of another crystalline thermoplastic resin is used as cooling water for strands or chips. Hereinafter, the present invention will be described in detail.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a polyester resin has a ratio of oxyethylene oxyterephthaloyl units (hereinafter referred to as "ET units") composed of terephthalic acid and ethylene glycol of 8 to all constitutional repeating units.
0 eq% or more of polyethylene terephthalate (hereinafter abbreviated as “PET”);
May contain structural repeating units other than ET units in a range of less than 20 equivalent%. PET in the present invention is:
It is produced using terephthalic acid or its lower alkyl ester and ethylene glycol as main raw materials, but as described above, other acid components and / or other glycol components may be used in combination.

The acid components other than terephthalic acid include phthalic acid, isophthalic acid, naphthalenedicarboxylic acid,
4'-diphenylsulfonedicarboxylic acid, 4,4'-biphenyldicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 1,3-phenylenedioxydiacetic acid and structural isomers thereof, malonic acid, succinic acid, adipic acid, etc. Dicarboxylic acid and derivatives thereof, p-hydroxybenzoic acid,
Oxy acids such as glycolic acid and derivatives thereof are listed.

Diol components other than ethylene glycol include aliphatic diols such as 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, pentamethylene glycol, hexamethylene glycol and neopentyl glycol. Examples thereof include alicyclic glycols such as glycol and cyclohexanedimethanol, and aromatic dihydroxy compound derivatives such as bisphenol A and bisphenol S.

The raw material containing terephthalic acid or its ester-forming derivative and ethylene glycol as described above is converted to bis (β-hydroxyethyl) by an esterification reaction or a transesterification reaction in the presence of an esterification catalyst or a transesterification catalyst. ) A terephthalate and / or an oligomer thereof is formed, and then a melt polycondensation is carried out at a high temperature under reduced pressure in the presence of a polycondensation catalyst and a stabilizer to obtain a polymer.

The esterification catalyst does not need to be particularly used because terephthalic acid serves as an autocatalyst in the esterification reaction. Further, the esterification reaction can be carried out in the presence of an esterification catalyst and a polycondensation catalyst described below,
Further, it can be carried out in the presence of a small amount of an inorganic acid or the like.
As the transesterification catalyst, 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 are preferably used, and manganese compounds are particularly preferable from the viewpoint of transparency. .

As the polycondensation catalyst, compounds soluble in the reaction system such as a germanium compound, an antimony compound, a titanium compound, a cobalt compound and a tin compound are used alone or in combination. As the polycondensation catalyst, germanium dioxide is particularly preferred from the viewpoint of color tone and transparency.
Examples of the stabilizer include phosphoric esters such as trimethyl phosphate, triethyl phosphate and triphenyl phosphate; phosphites such as triphenyl phosphite and trisdodecyl phosphite; methyl acid phosphate; dibutyl phosphate; and monobutyl phosphate acidic phosphorus. Phosphorus compounds such as acid esters, phosphoric acid, phosphorous acid, hypophosphorous acid, and polyphosphoric acid are preferred.

The use ratio of the above-mentioned catalyst is as follows:
Usually 5 to 2000 ppm by weight of metal in the catalyst,
It is preferably in the range of 10 to 500 ppm, and the proportion of the stabilizer used is generally 10 to 1000 ppm, preferably 20 to 100 ppm, as the weight of phosphorus atoms in the stabilizer in all the polymerization raw materials.
It is in the range of 200 ppm. The supply of the catalyst and the stabilizer can be performed at any stage of the esterification reaction or the transesterification reaction in addition to the preparation of the raw material slurry.
Furthermore, it can be supplied at the beginning of the polycondensation reaction step.

The reaction temperature during the esterification or transesterification is usually from 240 to 280 ° C., and the reaction pressure is usually from 1 to 3 kg / cm ² G. The reaction temperature during the polycondensation reaction is usually from 250 to 300 ° C, and the reaction pressure is usually from 500 to 0.1 mmHg. Such esterification or transesterification reaction and polycondensation reaction may be performed in one stage or may be performed in a plurality of stages. The polyester thus obtained has an intrinsic viscosity of usually 0.4
5 to 0.70 dl / g.

The produced polymer is drawn out in a strand form in the atmosphere from a discharge port provided at the bottom of the polycondensation tank and cooled in a water tank.
It is cut into elliptical column-shaped chips of 5 mm, a short diameter of 1 to 5 mm, and a length of 2 to 5 mm. In the present invention. The polymer is modified by adding another crystalline thermoplastic resin powder into a water tank for cooling the strands or chips and bringing the strands or chips into contact with the powder during cooling.

In this case, a polyolefin resin or a polyamide resin is used as the other crystalline thermoplastic resin. As the polyolefin resin, for example,
Homopolymers of α-olefins having about 2 to 8 carbon atoms such as ethylene, propylene, butene-1, etc., and those α-olefins and ethylene, propylene, butene-1,3-methylbutene-1, pentene-1,4 -Methylpentene-
1, other hexene-1, octene-1, decene-1 and other α-olefins having about 2 to 20 carbon atoms, vinyl acetate,
Vinyl chloride, acrylic acid, methacrylic acid, acrylic acid ester, methacrylic acid ester, copolymers with vinyl compounds such as styrene and the like, specifically, for example,
Ethylene homopolymer, ethylene-propylene copolymer such as low / medium / high density polyethylene (branched or linear),
Ethylene-butene-1 copolymer, ethylene-4-methylpentene-1 copolymer, ethylene-hexene-1 copolymer, ethylene-octene-1 copolymer, ethylene-vinyl acetate copolymer, ethylene-acryl Ethylene resins such as acid copolymer, ethylene-methacrylic acid copolymer, ethylene-ethyl acrylate copolymer, propylene homopolymer, propylene-ethylene copolymer, propylene-ethylene-butene-1 copolymer, etc. Butene-1 such as butene-1 homopolymer, butene-1-ethylene copolymer, butene-1-propylene copolymer, etc.
And the like.

Examples of the polyamide resin include lactam polymers such as butyrolactam, δ-valerolactam, ε-caprolactam, enantholactam, ω-laurolactam, 6-aminocaproic acid, 11-aminoundecanoic acid, and the like. Polymers of aminocarboxylic acids such as 12-aminododecanoic acid, hexamethylenediamine, nonamethylenediamine, decamethylenediamine, dodecamethylenediamine, undecamethylenediamine, 2,2,4-
Or an aliphatic diamine such as 2,4,4-trimethylhexamethylenediamine, an alicyclic diamine such as 1,3- or 1,4-bis (aminomethyl) cyclohexane, bis (p-aminocyclohexylmethane), m- Or a diamine unit such as an aromatic diamine such as p-xylylenediamine;
Polycondensates with dicarboxylic acid units such as aliphatic dicarboxylic acids such as glutaric acid, adipic acid, suberic acid and sebacic acid, alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid, and aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid. , And copolymers thereof, and the like. Specifically,
For example, nylon 4, nylon 6, nylon 7, nylon 8, nylon 9, nylon 11, nylon 12, nylon 6,6, nylon 6,9, nylon 6,10, nylon 6,11, nylon 6,12, nylon 6T , Nylon 6I, nylon MXD6, nylon 6 / 6,6, nylon 6 / 6,10, nylon 6/12, nylon 6 /
6T, nylon 6I / 6T and the like.

These crystalline thermoplastic resins are usually 20
100 mesh, preferably as a powder 40-80 mesh, with respect to the cooling water 1 m ^3, usually 0.1~10p
pm, preferably 1-5 ppm, the amount of which is
The mixing ratio of the crystalline resin in the ET resin is adjusted to be preferably in the range of 0.1 to 100 ppb, more preferably 5 to 50 ppb, based on the total amount with the PET resin.

Next, the polymer obtained by melt polycondensation as described above is usually subjected to solid phase polymerization. The polymer chip to be subjected to solid-phase polymerization may be preliminarily crystallized by heating to a temperature lower than the temperature at which solid-phase polymerization is performed, and then subjected to solid-phase polymerization. Such pre-crystallization is performed by (a) heating the dried polymer chips at a temperature of usually 120 to 200 ° C., preferably 130 to 180 ° C. for 1 minute to 4 hours, and (b) drying the polymer chips. In a steam or inert gas atmosphere containing steam, usually 120 to 200
(C) a method of heating a polymer chip that has been humidified and conditioned in an atmosphere of water, water vapor or an inert gas containing water vapor at a temperature of usually 120 to 200 ° C. for 1 minute or more. Can be done.

The humidity control of the polymer chip is carried out at a water content of usually 100 to 10000 ppm, preferably 1000 to 5 ppm.
It is carried out so as to be in the range of 000 ppm. By subjecting the conditioned polymer chip to crystallization or solid-state polymerization,
It is possible to further reduce the amount of acetaldehyde and a small amount of impurities contained in PET.

The solid phase polymerization step comprises at least one step, usually at 190 to 230 ° C., preferably at 195 to 225.
C., a polymerization temperature of usually 1 kg / cm ² G to 10 mmHg,
It is preferably carried out under a polymerization pressure of 0.5 kg / cm ² G to 100 mmHg under a flow of an inert gas such as nitrogen, argon or carbon dioxide. The solid-state polymerization time may be shorter as the temperature is higher, but is usually 1 to 50 hours, preferably 5 to 30 hours, and more preferably 10 to 25 hours.
The intrinsic viscosity of the polymer obtained by solid-state polymerization is usually in the range of 0.72 to 0.85 dl / g.

In the present invention, the content of diethylene glycol units (hereinafter abbreviated as "DEG") constituting the polyester resin finally obtained by the above method and the cyclic trimer (hereinafter "CT") in the polyester resin are obtained. ) Must be within a specific range. By satisfying such conditions, it is possible to obtain a polyester resin composition which is excellent in continuous moldability and controls the crystallization rate without impairing transparency, and is particularly suitable for bottles.

In the present invention, the amount of DEG constituting the finally obtained polyester resin is 1.0 to 2.5 mol%, preferably 1.2 to 2.2 mol, based on all diol units constituting the polyester. Mol%. If the DEG amount is too small, the transparency of the body of the bottle after molding deteriorates. On the other hand, if the amount is too large, the heat resistance decreases, and the effect of promoting crystallization decreases.

As a method for adjusting the amount of DEG within the above range, in addition to using diethylene glycol as a polymerization raw material, since ethylene glycol used as a main raw material partially produces diethylene glycol as a by-product, reaction conditions, additives and the like may be appropriately adjusted. There is a method of adjusting the amount of by-products by selection.

The above-mentioned additives include, for example, tertiary amines such as triethylamine, tri-n-butylamine and benzyldimethylamine, and hydroxides such as tetraethylammonium hydroxide, tetrabutylammonium hydroxide and trimethylbenzylammonium hydroxide. Basic compounds such as quaternary ammonium, lithium carbonate, sodium carbonate, potassium carbonate, and sodium acetate are exemplified. By adding these small amounts, the generation of DEG can be suppressed. On the other hand, if a small amount of an inorganic acid such as sulfuric acid or an organic acid such as benzoic acid is added to the raw material for polymerization, the production of DEG can be promoted and the content of DEG can be increased. If necessary, the above additive for controlling the amount of DEG produced is usually from 0.001 to 10% by weight, preferably from 0.1 to 10% by weight of the whole polymerization raw material.
It is used in the range of 005 to 1% by weight.

The CT content in the finally obtained polyester resin is 0.5% by weight or less, preferably 0.1% by weight.
It is at most 45% by weight, more preferably at most 0.4% by weight, most preferably at most 0.35% by weight. 0.5% by weight
When the value exceeds, contamination of the mold and the like is remarkably recognized, and the body of the molded body is easily whitened. The CT amount can be reduced by increasing the solid-state polymerization temperature and further increasing the polymerization time.

Furthermore, in order to enhance the effect of reducing CT, the concentration of terminal carboxyl groups in the polymer after melt polycondensation subjected to solid-state polymerization is preferably in the range of 10 to 30 eq / ton. It is particularly preferred to be in the range of 25 eq / ton. When the concentration of the terminal carboxyl group is less than the above range, the solid-state polymerization property is poor and it may take a long time to increase the intrinsic viscosity. In some cases, the effect of reducing oligomers such as CT may be small.

The polyester resin composition of the present invention is obtained by injection molding at a molding temperature of 280.degree. T _c1 ) is from 155 ° C to 17 ° C.
The temperature is preferably 2 ° C, particularly preferably 160 to 170 ° C. When T _c1 is less than the above range, the shoulder and the trunk may be whitened at the time of crystallization of the plug portion of the bottle obtained by molding and heat treatment of the bottle, thus impairing transparency. On the other hand, when T _c1 exceeds the above range, it is difficult to obtain a sufficient effect of improving the crystallization rate. By satisfying the above condition of T _c1 , both physical properties of crystallinity and transparency of the molded article can be sufficiently satisfied at the same time.

The injection molding conditions in the present invention are within the range normally employed. For example, in the case of polyester resin in general, the cylinder temperature is 270 to 300.
° C, mold temperature 5-40 ° C, screw rotation speed 40-30
Molding can be performed at a range of 0 rpm and an injection pressure of 40 to 140 kg / cm ² . Injection molded products obtained by the above injection molding method, for example, a preform is made into a hollow container by a blow molding method such as a cold parison method of biaxially stretching after reheating, for example, carbonated drinks, fruit drinks, alcoholic drinks, Beverages such as tea and mineral water, soy sauce, sauces, mirin, liquid detergents such as dressing,
It is suitably used as a container for cosmetics and the like.

[0031]

EXAMPLES The present invention will be described in more detail with reference to the following Examples, but it should not be construed that the present invention is limited to the following Examples unless it exceeds the gist of the invention. The various measurement methods used in this example are described below.

(1) Intrinsic viscosity (hereinafter referred to as “IV”) Measured at 30 ° C. in a mixed solvent of phenol / tetrachloroethane (weight ratio 1/1). (2) Haze An injection molding machine (manufactured by Meiki Seisakusho Co., Ltd.) in which the temperature of each part of the cylinder and the nozzle head was set to 280 ° C., the screw rotation speed was set to 200 rpm, the injection time was set to 60 seconds, and the mold cooling water temperature was set to 10 ° C. M-70A "), the portions having a thickness of 4 mm and 5 mm of the stepped molded plate obtained by the method were measured with a haze meter (" NDH-300A "manufactured by Nippon Denshoku Co., Ltd.).

(3) Crystallization temperature Differential scanning calorimeter (“DSC22” manufactured by Seiko Instruments Inc.)
0C "), and a 5 mm thick portion of a stepped molded plate was used as a sample. 20 from room temperature to 285 ° C
The top temperature of the crystallization peak observed during the heating at a rate of ° C./min was taken as the heating crystallization temperature (T _C1 ). The temperature was further increased and maintained for 3 minutes from when the temperature reached 285 ° C., and then the temperature was lowered at a rate of 10 ° C./min. The top temperature of the crystallization peak observed at this time was defined as the cold crystallization temperature (T _c2 ).

(4) Transparency of Bottle An injection molding machine (Toshiba (Toshiba Corporation) in which the temperature of each part of the cylinder and the nozzle head was set to 280 ° C., the screw rotation speed was set to 100 rpm, the injection time was set to 10 seconds, and the mold cooling water temperature was set to 10 ° C. The preform is molded by “IS-60B” manufactured by the Company), and then the preheating furnace temperature is set to 90 ° C. and the blow pressure is set to 20 k.
g / cm ² , and a molding cycle set at 10 seconds using a stretch blow molding machine.
A liter bottle was used to determine the transparency by visual inspection.

(5) Amount of cyclic trimer (hereinafter referred to as “CT amount”) 200 mg of a PET sample was dissolved in 2 ml of a chloroform / hexafluoroisopropanol (volume ratio: 3/2) mixture, and further diluted with 20 ml of chloroform. . A sample was reprecipitated by adding 10 ml of methanol thereto, and then filtered to obtain a filtrate. After the filtrate was dried, the residue was dissolved in 25 ml of dimethylformamide and analyzed and quantified by liquid chromatography.

(6) Diethylene glycol (hereinafter referred to as "DE
G amount) 4N-KOH methanol solution 50 was added to 5.0 g of PET sample.
Milliliter was added, and the mixture was heated under reflux with stirring to hydrolyze. The diol component produced by the operation was quantified by gas chromatography.

Example 1 13.0 kg of terephthalic acid and ethylene glycol5.
82 kg of a slurry was prepared, and 0.30 kg of bis (2-hydroxyethyl) terephthalate was previously added to the slurry and supplied to the esterification tank maintained at a temperature of 250 ° C. over 4 hours. After the completion of the supply, the esterification reaction was allowed to proceed for 1 hour, and then half the amount was transferred to a polycondensation tank, and 0.91 g of phosphoric acid was added.
(Relative to polymer 120 ppm), germanium dioxide 0.
92 g (based on the polymer: 120 ppm) was charged at 250 ° C.
, And gradually reduced from normal pressure to 0.5 mmHg. After the reaction is carried out for 3 hours, the produced polymer is withdrawn in a strand form from a withdrawal outlet provided at the bottom of the polycondensation tank to form a chip having an elliptical column shape using a cutter. Nippon Polychem Co., Ltd. Low Density Polyethylene U
E320) was added as a powder and 1 ppm was added. When the polymer after cooling was analyzed, 14 ppb of PE was detected. The melt-polymerized chips obtained here were stirred using a SUS pneumatic transportation pipe (diameter 100 mm) and agitated and crystallized (Bepe).
(company x).

Next, the above-mentioned polymer chip surface was crystallized at 150 ° C. using a stirring crystallizer (Bepex company formula), and then transferred to a stationary solid-state polymerization tower, where it was 20 l / kg · h.
After drying at about 140 ° C. for 3 hours under nitrogen flow of r,
For 20 hours to obtain a solid-phase polymerization chip. The physical property value of each of the solid-phase polymerization chips is intrinsic viscosity = 0.76.
dl / g, DEG = 2.1 mol%, CT = 3800p
pm and the particle weight was 24.0 mg / piece.

This polyester resin was dried in a vacuum drier to 14
It was dried at 0 ° C. for 12 hours. The thermoplastic polyester resin was molded at a molding temperature of 28 using M-70A manufactured by Meiki Seisakusho Co., Ltd.
Molding was performed at 0 ° C. to obtain stepped plate-like molded plates. The physical properties of the obtained molded plate are shown in Table 1 below. The transparency and the crystallization temperature obtained here were evaluated. For the evaluation of the transparency, the haze was measured using a haze meter NDH-300A manufactured by Nippon Denshoku Co., Ltd. at a thickness of 4 and 5 mm of each plate-shaped molded plate.

Evaluation of crystallization was performed using a differential scanning calorimeter DSC220C manufactured by Seiko Denshi Co., Ltd., and a 5 mm thick portion of each plate-like molded plate was used as a sampling point. The top temperature of the crystallization peak observed during the temperature rise from room temperature to 285 ° C. at a rate of 20 ° C./min was taken as the temperature rise crystallization temperature (T _c1 ). The temperature was further increased and maintained for 3 minutes from when the temperature reached 285 ° C., and then the temperature was lowered at a rate of 10 ° C./min. The top temperature of the crystallization peak observed at this time was defined as the cold crystallization temperature (T _c2 ).

The above-mentioned dried thermoplastic polyester
ASB-50TH, Nissei ASB Machine Co., Ltd.
Screw diameter 38 mm, screw length 760 mm)
And set the cylinder temperature to 285 ° C
The mold set temperature is 20 ° C, the injection holding time is 14 seconds,
Rejection time 10 seconds, primary injection pressure 140kg / cm^Two,
Secondary injection pressure is 40kg / cm^Two, Weighing speed 100
rpm, back pressure 5kg / cm^Two, Blow mold set temperature
160 ° C, blow pressure 15-30kg / cm ^Two, Bro
-Time is 15 seconds, outer diameter 100mmφ, length 3
00mm, wall thickness 0.35mm, content 1560ml, eye
A 60 g bottle was formed. Molding cycle at this time
Was performed in 30 seconds. Physical properties of the finally obtained bottle
The transparency was visually evaluated as a value. Evaluation criteria
Was determined based on the following criteria. At this time
Table 1 shows the physical properties of the bottle. ：: good without deformation and turbidity; △: transparent but deformed
X: whitening due to crystallization.

Comparative Example 1 In the step of chipping the polyethylene terephthalate resin after the melt polymerization, a method similar to that of Example 1 was used except that water to which a crystalline thermoplastic resin was not added was used as cooling water for chips. A polyethylene terephthalate resin was obtained.
The physical properties of the solid-state polymerization chips obtained above were as follows: intrinsic viscosity = 0.75 dl / g, DEG = 2.1 mol%, C
T = 3900 ppm, particle weight 24.1 mg / piece, PE content = 0 ppb. After drying the polyethylene terephthalate resin in a vacuum dryer at 140 ° C. for 12 hours,
In the same manner as in Example 1, step-shaped plate-like molded plates and bottles were molded and subjected to the same evaluation.

[0043]

[Table 1]

[0044]

By using the method for producing a polyester resin according to the present invention, it is possible to provide a polyester resin having a controlled crystallization rate without impairing the transparency.

Claims (4)

[Claims] In a step of forming a polyester resin chip after melt polymerization obtained by polymerizing a dicarboxylic acid component containing terephthalic acid or a lower alkyl ester thereof and a glycol component containing ethylene glycol as a main component, a strand is used. Alternatively, a method for producing a modified polyester resin, wherein water containing powder of another crystalline thermoplastic resin is used as cooling water for chips. 2. The method according to claim 1, wherein the other crystalline thermoplastic resin is a polyolefin resin or a polyamide resin. 3. The method according to claim 2, wherein the polyolefin resin is polyethylene or polypropylene. 4. The content of the resin powder in cooling water is 0.1%.
4. The composition according to claim 1, wherein the amount is from 10 to 10 ppm.
The production method according to any one of the above.