JP2000226444A - Polyester resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyester resin capable of giving a molding, especially, a blow molding, excellent in transparency and heat-resistant dimensional stability by selecting a polyester resin mainly consisting of repeating ethylene terephthalate units and prepared by using a catalyst comprising an Sb compound and a Ti compound and/or a Ge compound and giving a stretched molding and a stretched heat-set molding each having a specified haze. SOLUTION: This resin gives a stretched molding having a haze of at most 2.0% and a stretched heat-molding having a haze of at most 5.0%. It is desirable that an amorphous molding molded from the resin has a density of at most 1.338 g/cm3 when it is heated at 140 deg.C for 60 sec and has a rate of density increase of 0.2×10-3 to 0.6×10-3 at 140 deg.C, and the amorphous molding has a density of at most 1.338 g/cm3 when it is heated at 180 deg.C for 20 sec and a rate of density increase of 0.8×10-3 to 3.0×10-3 g/cm3.sec at 180 deg.C. In the course of producing the polyester, each of at least one member selected from among an Mg compound, a Ca compound, a Co compound, an Mn compound, and a Zn compound and a P compound are added to the system in at least two divided portions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a polyester resin used for molded articles such as bottles, films, sheets and the like. More specifically, the present invention relates to a molded article having excellent transparency and heat-resistant dimensional stability, particularly to a polyester resin which gives a hollow molded article.

[0002]

2. Description of the Related Art Polyester resins, especially polyethylene terephthalate (hereinafter abbreviated as "PET") are characterized by their excellent transparency, mechanical strength, heat resistance, gas barrier properties, and other properties. It is used as a material for containers such as water and mineral water, and its use has been remarkable.

[0003] PET generally used for such applications
Is produced mainly using terephthalic acid and ethylene glycol as raw materials, and using a germanium compound, an antimony compound, a titanium compound and a mixture thereof as a polycondensation catalyst.

Among the above-mentioned catalysts, antimony catalysts are used as catalysts for producing PET for fibers and films because of their low cost. However, compared to the case where a germanium compound or a titanium compound is used as a catalyst, the crystallization rate of the obtained PET is high, and it is very difficult to obtain a hollow molded article having excellent transparency.

In order to solve these problems, a germanium compound or a mixture of the compound and a titanium compound is used as a polycondensation catalyst. However, if an expensive germanium compound is used, the cost of PET becomes high.

As a method for solving such a problem,
For example, JP-A-6-279579 discloses a method in which the transparency is improved by regulating the ratio of the antimony compound to the phosphorus compound. However, the transparency of the hollow molded article made of PET obtained by this method is not sufficient.

Japanese Patent Laid-Open Publication No. Hei 10-36495 discloses a continuous process for producing a polyester having excellent transparency using antimony trioxide, phosphoric acid and a sulfonic acid compound. However, the polyester obtained by such a method has a problem in that the heat stability is poor and the acetaldehyde content of the obtained hollow molded article is high.

[0008]

DISCLOSURE OF THE INVENTION The present invention solves such a problem and provides a molded article having excellent transparency.
An object is to provide an inexpensive polyester resin.

[0009]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have reached the present invention.
That is, the polyester resin of the present invention is a polyester resin produced by using an antimony compound and a titanium compound or / and a germanium compound as a catalyst and having a main repeating unit of ethylene terephthalate, which is stretched by the method specified in the text. The haze of the molded body obtained was 2.
A polyester resin characterized by having a haze of not more than 0% and a molded article which has been heat-stretched and stretched by the method specified in the text, not more than 5.0%. The polyester resin having the above properties gives a molded article excellent in transparency and heat resistance dimensional stability, particularly a hollow molded article.

In this case, (a) the density of the amorphous molded article molded from the polyester resin when heated at 140 ° C. for 60 seconds is 1.338 (g / cm ³ ) or less and at 140 ° C. Density increase rate is 0.2 × 10 ^{-3 to} 0.6
× 10 ⁻³ (g / (cm ³ · second)), and (b) the density when the amorphous molded body is heated at 180 ° C. for 20 seconds is 1.338 (g / cm ³ ) or less. And 180
The density rise rate at 0.8 ° C. is 0.8 × 10 ^{−3 to} 3.0 × 10 ^−3.
(G / (cm ³ · second)).

In this case, the intrinsic viscosity is 0.70 to 0.70.
0.90 dl / g, the amount of copolymerized DEG is glycol
1.5-5.0 mol% of the components and a density of 1.37 g /
cm ^ThreeThat is all.

In this case, the content of acetaldehyde can be 10 ppm or less and the content of cyclic trimer can be 0.35% by weight or less.

[0013] In this case, the polyester resin may be for a hollow molded article.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail. The polyester resin having a main repeating unit of ethylene terephthalate in the present invention is a linear polyester resin containing at least 85 mol% of ethylene terephthalate units, preferably at most 90 mol%, more preferably at least 95 mol%. It is a linear polyester resin.

The dicarboxylic acids used for the copolymerization of the polyester resin include aromatic acids such as isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl-4,4'-dicarboxylic acid and diphenoxyethanedicarboxylic acid. Dicarboxylic acids and their functional derivatives, p-oxybenzoic acid, oxyacids such as oxycaproic acid and their functional derivatives, adipic acid, sebacic acid, succinic acid, aliphatic dicarboxylic acids such as glutaric acid and their functional derivatives, Alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid and functional derivatives thereof;

Glycols used for copolymerization of the polyester resin include aliphatic glycols such as diethylene glycol, trimethylene glycol, tetramethylene glycol and neopentyl glycol, and alicyclic groups such as cyclohexanedimethanol. And aromatic glycols such as glycol, bisphenol A and alkylene oxide adducts of bisphenol A.

Further, as other copolymerization components comprising a polyfunctional compound in the polyester resin, trimellitic acid, pyromellitic acid and the like can be mentioned as acid components, and glycerin, pentaerythritol and the like can be mentioned as glycol components. Can be mentioned. The amount of the copolymerization component composed of these polyfunctional compounds must be such that the polyester resin maintains a substantially linear shape.

The polyester resin of the present invention is a polyester resin having a main repeating unit of ethylene terephthalate produced using an antimony compound and a titanium compound and / or a germanium compound as a catalyst. The haze of the stretched molded article is 2.0% or less, preferably 1.5% or less, more preferably 1.0% or less, and the heat of the stretched and heat-fixed molded article according to the method specified in the text. The polyester resin is characterized in that the polyester resin is 5.0% or less, preferably 3.5% or less, more preferably 2.0% or less. The haze of the molded article stretched by the method specified in the text is 2.0%
When the haze of the heat-stretched molded product exceeds 5.0% and the haze of the heat-stretched molded product exceeds 5.0%, the transparency of the obtained molded product, particularly the heat-stretched molded product, is extremely low. become worse.

Further, the polyester resin of the present invention comprises:
(A) an amorphous molded article molded from the polyester resin,
The density when heated at 140 ° C. for 60 seconds is 1.338 (g)
/ Cm ³ ) or less, preferably 1.337 (g / cm ³ ) or less, and the density increasing rate at 140 ° C. is 0.2 × 10 ^−3.
０．６0.6 × 10 ^-3 (g / (cm ³ · sec)), preferably 0.25 × 10 ^{-3 to} 0.55 × 10 ^-3 (g / (cm ³ ·
Seconds)) and (b) the amorphous compact
The density when heated at 80 ° C. for 20 seconds is 1.338 (g / g).
cm ³ ) or less, preferably 1.337 (g / cm ³ ) or less, and the density increasing rate at 180 ° C. is 0.8 × 10 ⁻³ or less.
3.0 × 10 ⁻³ (g / (cm ³ · second)), preferably 0.9 × 10 ^{−3 to} 2.5 × 10 ⁻³ (g / (cm ³ •
(Sec)). When a polyester resin having the above haze characteristics and crystallization characteristics is used, a hollow molded container having particularly excellent transparency and heat resistance can be obtained.

The density when heated at 140 ° C. for 60 seconds is 1.338 (g / cm ³ ) or more, and the density rise rate at 140 ° C. is 0.6 × 10 ^-3 (g / (cm ³ · second). )) And the density when heated at 180 ° C. for 20 seconds is 1.
When the density is 338 (g / cm ³ ) or more and the density increase rate at 180 ° C. is 3.0 × 10 −3 (g / (cm ³ · second)) or more, the obtained molded product, particularly, stretch molding Transparency of the body becomes very poor. Density rise rate at 140 ° C is 0.2 ×
10 ⁻³ (g / (cm ³ · sec)) or less and the density increasing rate at 180 ° C. is 0.8 × 10 ⁻³ (g / (cm ³ · sec).
Second)) In the following cases, the heat resistance of the obtained molded product is deteriorated.

[0021] The polyester resin of the present invention comprises terephthalate
A direct esterification method in which water is distilled off and esterified by directly reacting the acid with ethylene glycol and / or the third component, followed by polycondensation under reduced pressure, or dimethyl terephthalate and ethylene glycol And / or transesterification by removing the methyl alcohol by reacting the third component and subjecting the mixture to transesterification, followed by transesterification in which polycondensation is performed under reduced pressure. In this production process, a Mg compound, a Ca compound, At least one metal compound selected from a Co compound, a Mn compound and a Zn compound and a P compound are added in two or more portions, and a polycondensation reaction is performed after the esterification or transesterification is substantially completed. It can be obtained by adding a Sb compound and a Ti compound or a / Ge compound and performing polycondensation before.

Further, in order to increase the molecular weight of the polyester resin and reduce the acetaldehyde content, solid phase polymerization may be performed.

The above-mentioned esterification reaction, transesterification reaction, melt polycondensation reaction and solid-state polymerization reaction may be carried out in a batch reactor or in a continuous reactor.

The Mg compound, Ca compound, Co compound, Mn compound and Zn compound used in the present invention can be used as long as they are soluble in the reaction system.

Examples of the Mg compound include lower fatty acid salts such as magnesium hydride, magnesium oxide and magnesium acetate, and alkoxides such as magnesium methoxide.

As the Ca compound, calcium hydride,
Examples thereof include lower fatty acid salts such as calcium hydroxide and calcium acetate, and alkoxides such as calcium methoxide.

Examples of the Co compound include lower fatty acid salts such as cobalt acetate, organic acid salts such as cobalt naphthenate and cobalt benzoate, chlorides such as cobalt chloride, and cobalt acetylacetonate.

Examples of the Mn compound include organic acid salts such as manganese acetate and manganese benzoate; chlorides such as manganese chloride;
Alkoxides such as manganese methoxide, manganese acetylacetonate and the like can be mentioned.

Examples of the Zn compound include organic acid salts such as zinc acetate and zinc benzoate, chlorides such as zinc chloride, alkoxides such as zinc methoxide, and zinc acetylacetonate. As the P compound used in the present invention,
Phosphoric acid, phosphorous acid, phosphonic acid, and derivatives thereof. Specific examples include phosphoric acid, trimethyl phosphate, triethyl phosphate, tributyl phosphate, triphenyl phosphate, monomethyl phosphate, dimethyl phosphate, monobutyl phosphate, dibutyl phosphate, and dibutyl phosphate. Phosphoric acid, trimethyl phosphite, triethyl phosphite, tributyl phosphite, 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,
These may be used alone or in combination of two or more.

The Sb compound used in the present invention includes:
Examples include antimony trioxide, antimony acetate, antimony tartrate, antimony potassium tartrate, antimony oxychloride, antimony glycolate, antimony pentoxide, and triphenylantimony.

The Ti compound used in the present invention includes:
Tetraethyl titanate, tetraisopropyl titanate
And tetraalkyl titanates such as tetra-n-propyl titanate and tetra-n-butyl titanate and partial hydrolysates thereof, titanyl oxalate, titanyl ammonium oxalate, sodium titanyl oxalate, potassium titanyl oxalate, titanyl oxalate Examples include calcium, titanyl oxalate compounds such as titanylstrontium oxalate, titanium trimellitate, titanium sulfate, and titanium chloride.

Ge compounds used in the present invention include:
Examples include amorphous germanium dioxide, crystalline germanium dioxide, germanium chloride, germanium tetraethoxide, germanium tetra-n-butoxide, and germanium phosphite. Mg compound, Ca compound, Co compound, Mn compound and Zn used in the present invention
The compound has at least two components during the production of the polyester resin.
It is preferable to add it in divided portions or more, and the content in the produced polymer is 0.1% in the polymer-1 ton as a metal atom.
It is added so as to be in a range of 1 to 5.0 mol.

It is preferable that the P compound used in the present invention be added at least twice in the course of the production of the polyester resin, and that the Mg compound and the Ca compound be contained in the polymer with respect to the P atoms in the produced polymer. , Co compound, Mn compound and Zn compound in a total metal atom ratio of 0.1 to 3.0.

Mg compound, Ca compound, Co compound, M
The method of adding the n-compound, Zn-compound and P-compound in a divided manner is to stagger the addition time when the production of the polyester resin is carried out batchwise, or to change the place of addition when carrying out the continuous production. Can be performed. When the production of the polyester resin is performed in a continuous manner, a method of increasing the number of reaction vessels and separately adding the reaction vessels to at least two reaction vessels, separately adding at least two or more locations in the same reaction vessel in the progress of the reaction. And various methods such as a method of line-mixing a reaction vessel and a continuous section of the reaction vessel.

Mg compound, Ca compound, Co compound, M
As for the division ratio of the addition amount of the n compound and the Zn compound, the initial addition amount is preferably about 50% or less of the total addition amount, and particularly preferably 30% or less.

The dividing ratio of the added amount of the P compound is preferably such that the initial added amount is about 50% or less of the total added amount.
It is particularly preferred that the content be 0% or less. In addition, Mg compound, Ca compound, Co compound, Mn compound and Zn
Preferably, it is added after the addition of the compound.

The first Mg compound, Ca compound, Co compound
The addition time of the compound, the Mn compound, the Zn compound and the P compound may be before or during the esterification and transesterification reaction, or after the completion, but the addition time after the second time is during the esterification or transesterification reaction. Or after termination.

The Sb compound used in the present invention is added so that the content in the resulting polymer is in the range of 0.1 to 1.7 mol per metal ton as metal atoms.

The Ti compound used in the present invention is
It is added so that the content in the resulting polymer is in the range of 0 to 0.4 mol as metal atoms in 1 ton of the polymer.

The Ge compound used in the present invention is:
It is added so that the content in the resulting polymer is in the range of 0 to 0.7 mol as metal atoms in 1 ton of the polymer.

The limiting viscosity of the polyester resin of the present invention is as follows:
0.57 to 0.90 dl / g, preferably 0.58 to
0.88 dl / g, more preferably 0.60 to 0.8
It is in the range of 5 dl / g. At 0.57 dl / g or less,
The mechanical properties of the obtained molded product are poor. Also, 0.90
When the dl / g exceeds dl / g, the resin temperature rises during melting by a molding machine or the like, and the thermal decomposition becomes severe, the amount of free low-molecular-weight compounds that affect fragrance retention increases, or the molded product is colored yellow. And other problems occur.

The amount of diethylene glycol constituting the polyester resin of the present invention is 1.5 to 1.5 of the glycol component.
It is 5.0 mol%, preferably 1.6 to 4.5 mol%, and more preferably 1.7 to 4.0 mol%. When the amount of diethylene glycol is 1.5 mol% or less, the density of the molded article specified in the present invention does not fall within the range specified in the present invention because the crystallization rate is high, and the transparency of the obtained molded article is poor. become worse. When the amount of diethylene glycol is 5.0 mol% or more, the glass transition point of the polyester resin decreases, the heat resistance of the obtained molded article decreases, and the acetaldehyde content during molding decreases due to poor heat stability. The amount of increase is large,
It has a bad effect on scent retention.

The acetaldehyde content of the polyester resin of the present invention is 10 ppm or less, preferably 8 ppm.
Or less, more preferably 5 ppm or less. When the content of acetaldehyde is 10 ppm or more, the contents such as containers molded from the polyester resin have poor flavor and odor.

The cyclic 3 of the polyester resin of the present invention
The content of the monomer is 0.35% by weight or less, preferably 0.3% by weight.
It is at most 3% by weight, more preferably at most 0.32% by weight. When molding a heat-resistant hollow molded article or the like from the polyester resin of the present invention, heat treatment is performed in a heating mold. However, when the content of the cyclic trimer is 0.35% by weight or more, the heating mold is used. Oligomer attachment to the mold surface increases sharply,
The transparency of the obtained hollow molded article and the like is extremely deteriorated. The polyester resin of the present invention can be formed into a hollow molded product, a film, a sheet, or the like by a generally used melt molding method. When a hollow molded article is produced, a transparent, heat-resistant hollow molded article can be produced from the polyester resin of the present invention using a known hot parison method or cold parison method.

In the case of producing a hollow molded article using the polyester resin of the present invention, first, a preform is molded by injection molding, and then this is stretch-blown and molded into a bottle. Injection molding is generally performed at an injection temperature of about 265 to about 300 ° C. and an injection pressure of about 30 to about 70 kg / cm ² to form a preform. The plug portion of this preform is crystallized by heat treatment. The preformed body obtained in this manner is used in an amount of about 80 to about 12 in the case of the cold parison method.
Preheat to 0 ° C, and about 80-
Cool to about 120 ° C. The preform is stretch blow molded in a blow mold at about 120 to about 210 ° C and then heat treated for about 0.5 to about 30 seconds. The stretching ratio is usually 1.3 to 3.5 times in the machine direction and 2 to 6 in the circumferential direction.
It is better to double.

The polyester resin of the present invention can also be used for a laminated film with a different kind of film, a laminated sheet, a laminated body with a metal plate, and a multilayer hollow molded article.

The polyester resin of the present invention may contain various additives such as known nucleating agents, stabilizers, antistatic agents, coloring agents, UV inhibitors, antioxidants, lubricants and mold release agents, if necessary. You may mix.

[0048]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. The method for measuring the main characteristic values will be described below.

1) Intrinsic viscosity (IV) It was determined from the solution viscosity at 30 ° C. in a 1,1,2,2-tetrachloroethane / phenol (2: 3 weight ratio) mixed solvent.

2) Diethylene glycol content (hereinafter referred to as [D
It was decomposed by methanol, and the amount of DEG was determined by gas chromatography, and expressed as a ratio (mol%) to the total glycol components.

3) Acetaldehyde content (hereinafter referred to as "AA content") A resin pellet sample / distilled water = 1 g / 2 ml was put into a glass ampoule purged with nitrogen, and the upper portion was sealed.
After extraction for a while, acetaldehyde in the extract after cooling was measured by high-sensitivity gas chromatography, and the concentration was determined as pp.
Indicated by m.

4) Cyclic trimer content of polyester resin A resin pellet sample was prepared by using hexafluoroisopropanol /
Dissolve in chloroform mixed solution, further add chloroform and dilute. After adding methanol to precipitate a polymer, the mixture is filtered. The filtrate was evaporated to dryness, made up to volume with dimethylformamide, and quantified by liquid chromatography.

5) Molding of Molded Product The dried polyester resin was molded using a M-100 injection molding machine manufactured by Meiki Seisakusho at a cylinder temperature of 290 ° C.
It is molded with a stepped flat mold cooled to 0 ° C. to obtain a stepped molded body. This stepped molded body is 2, 3, 4, 5, 6, 7, 8,
9, 10 and 11 mm thick molded plates of about 3 cm x about 5 cm square are provided in a step shape, and each piece weighs about 146 g
It is. A molded plate having a thickness of 2 mm is cut out for measurement of the rate of rise in density and a molded plate having a thickness of 5 mm is cut and used for measurement of haze (% haze).

6) Molding of stretched molded article Using a dried polyester resin, an M-M
Preform at resin temperature of 290 ° C by 100 injection molding machine
Was molded. After heating and crystallizing the plug portion of this preform with a home-made plug portion crystallizing device, using an LB-01 stretch blow molding machine manufactured by Co-Poplast Co., Ltd., about 2.5 times in the longitudinal direction, Biaxially stretch-blow-molded at a magnification of about 5 times in the circumferential direction, and formed into a 1500 ml hollow molded container (mean wall thickness 0.4 mm).
mm). In the stretched heat-set molded product, a preform was prepared under the same conditions as described above, and the plug portion of the preform was heated and crystallized with a home-made plug portion crystallization apparatus. Biaxially stretch blow-molded under the same conditions as above using an LB-01 stretch blow-molding machine, and then heat-set for 5 seconds in a mold set at about 140 ° C.
A 00 ml hollow molded container (body average wall thickness 0.4 mm) is molded.

7) Haze (haze degree%) A section cut from the body of the stretched molded article was
The measurement is performed using a Hex meter manufactured by Nippon Denshoku Co., Ltd.

8) Heat treatment of molded plate and calculation of density rise rate A molded plate having a thickness of 2 mm was cut out from a stepped molded body molded at a cylinder temperature of 290 ° C., and was controlled at a predetermined temperature in a silicon oil bath (stirring). After being immersed for a predetermined time, it is taken out quickly, put into n-hexane and rapidly cooled. After quenching, the silicon oil attached to the surface is washed with n-hexane, and the density is measured. The sample is heated at 140 ° C. and 180 ° C. at 10 second intervals. The heat treatment is
The test is repeatedly performed for five samples under one condition, and the average value of the sample density under each condition is determined. The heat treatment time at each temperature and the density value of the formed plate are plotted to obtain a density rise curve. From this density rise curve, the density rise speed at each temperature is determined as follows. That is, the density rise curve at 140 ° C., density 1.340 (g / cm ³⁾ the heating time corresponding to (t1 seconds) and density 1.360 (g / cm ³⁾ the heating time corresponding to (t2 seconds) Is calculated from the following equation. Density increase rate (g / cm ³ · sec) = 0.02 /
(T2−t1) The density rise curve at 180 ° C. shows a density of 1.345.
(G / cm ³⁾ the heating time corresponding to (t1 seconds) and density 1.365 (g / cm ³⁾ corresponding to the heating time (t2
Second), and is calculated from the above equation.

9) Density of polyester resin pellet: 25 using a density gradient tube of a mixed solvent of carbon tetrachloride / n-heptane.
Measure in ° C.

(Example 1) As an esterification apparatus, a first esterification reaction apparatus provided with a stirrer, a decomposer, a raw material charging port and a product outlet, and the inside of a reaction vessel were divided into two tanks, A stirrer was attached to the reaction tank, and a three-stage complete mixing tank type continuous esterification reaction apparatus comprising a second esterification reaction apparatus provided with a separator, a raw material inlet, and a product outlet was used. The molar ratio of EG to TPA 1.7 was added to the system where the reaction product was present in the first esterification reactor.
The EG slurry of TPA adjusted to the above was continuously supplied.
At the same time, an EG solution of magnesium acetate tetrahydrate is supplied from a supply port different from the EG slurry supply port of TPA to 0.33 mol (about 8 ppm with respect to the produced polyester resin) as Mg atoms per ton of produced polyester resin. At a normal pressure, an average residence time of 4 hours and a temperature of 25
The reaction was performed at 5 ° C. This reaction product is continuously taken out of the system and supplied to the first tank of the second esterification reactor,
It was taken out continuously from the second tank. The transfer from the first tank to the second tank employed an overflow method. An EG solution of phosphoric acid in an amount of 0.33 mol (about 10 ppm) as P atoms per ton of the produced polyester resin from the supply port on the inlet side of the first tank, the supply port on the inlet side of the second tank An EG solution of magnesium acetate tetrahydrate in such an amount as to give 0.94 mol (about 23 ppm) as Mg atoms per ton of the produced polyester resin, and 1 ton of the produced polyester resin from the supply port at the intermediate position of the second tank An EG solution of phosphoric acid in an amount of 0.61 mol (approximately 19 ppm) as P atoms per unit was continuously added, and the reaction was carried out at an ordinary pressure and an average residence time of 2.5 hours in each tank at a temperature of 260 ° C. I let it.

Next, the esterification reaction product was continuously taken out from the second esterification reactor and sent to a two-stage continuous polycondensation reactor equipped with a stirrer, a separator, a raw material charging port and a product outlet. Feeded continuously. From the polycondensation catalyst supply pipe connected to the transport pipe for the esterification reactant,
As Sb atoms per ton of the produced polyester resin: 1.
EG solution of antimony trioxide in an amount of 23 moles (about 150 ppm) and EG of tetrabutyl titanate in an amount of 0.06 moles (about 3 ppm) as Ti atoms per ton of the produced polyester resin The solution was supplied to the esterification reaction product, and polycondensation was performed under reduced pressure at about 270 ° C. in the continuous polycondensation reaction apparatus described above. IV of the obtained PET resin was 0.52. This resin was subsequently sent to a continuous solid-state polymerization apparatus and subjected to solid-state polymerization at about 205 ° C. under a nitrogen atmosphere. IV of the obtained PET resin is 0.74, D
EG content is 2.8 mol%, AA content is 3.0 pm, cyclic trimer content is 0.31 wt%, density is 1.400 g / c.
m ³ . The haze of the hollow molded article obtained by stretch-blowing the obtained PET resin by the above-described method and the hollow molded article obtained by heat-stretching the stretched resin were 0.9% and 1.8%, respectively, which were good. Further, a molded plate for density measurement was formed by the above-mentioned method, and heat treatment was performed to measure the density. 140 ° C
Density when heated for 60 seconds at 1.335 g / cm ³ , 1
The density rise rate at 40 ° C. is 0.38 × 10 ⁻³ (g / (c
m ³ · sec)), the density when heated at 180 ° C. for 20 seconds is 1.335 g / cm ³ , and the density rise rate at 180 ° C. is 1.27 × 10 ⁻³ (g / (cm ³ · sec) ))Met. Further, about 90 ° C.
After filling with hot water and capping with a capping machine, the hollow molded body was turned down and left to stand. Then, deformation of the plug portion and leakage of the contents were examined, but there was no problem.

Example 2 Using the same apparatus as in Example 1, the esterification reaction and melt polymerization were carried out under the same conditions as in Example 1 except that the amount and position of the metal compound added were changed. An EG solution of magnesium acetate tetrahydrate in such an amount as to give 0.42 mol (about 10 ppm) of Mg atoms per ton of the produced polyester resin from the supply port on the inlet side of the first tank of the second esterification reactor. An EG solution of phosphoric acid in an amount of 0.30 mol (approximately 9 ppm) as P atoms per ton of the produced polyester resin from the supply port at the intermediate position of the first tank; From the mouth as Mg atoms per ton of polyester resin produced: 1.
An EG solution of magnesium acetate tetrahydrate in an amount of 23 mol (about 30 ppm) and 1.0 mol (about 31 ppm) as P atoms per 1 ton of the produced polyester resin from the supply port at the intermediate position of the second tank. An EG solution of phosphoric acid was continuously added in such an amount as to obtain an esterification reaction. Then, in the same manner as in Example 1, 0.45 mol (approximately 55
ppm) as Ti atoms per ton of an EG solution-producing polyester resin of antimony trioxide.
A polycondensation reaction was carried out by supplying an EG solution of tetrabutyl titanate in an amount of 0.6 mol (about 3 ppm) to the esterification reaction product. IV of the obtained PET resin was 0.53. This resin was subsequently sent to a continuous solid-state polymerization apparatus and subjected to solid-state polymerization at about 205 ° C. under a nitrogen atmosphere. The obtained PET resin had an IV of 0.75, a DEG content of 3.3 mol%, an AA content of 3.7 ppm, a cyclic trimer content of 0.31 wt%, and a density of 1.400 g / cm ^3. Was.

The haze of the hollow molded article obtained by stretching and blowing the obtained PET resin by the above-described method and the haze of the hollow molded article obtained by stretching and heat setting were as good as 0.5% and 1.5%, respectively. Further, a molded plate for density measurement was formed by the above-mentioned method, and heat treatment was performed to measure the density. The density when heated at 140 ° C. for 60 seconds is 1.335 g / cm ³ , 14
The density rise rate at 0 ° C. is 0.35 × 10 ⁻³ (g / (cm
³ )), the density when heated at 180 ° C. for 20 seconds is 1.335 g / cm ³ , and the density rise rate at 180 ° C. is 1.15 × 10 ⁻³ (g / (cm ³ • second)). )Met.
In addition, hot water of about 90 ° C. was filled in the same manner as in Example 1,
After capping with a capping machine, the hollow molded body was turned down and left to stand. Then, the deformation of the plug portion and the leakage of the contents were examined, but there was no problem.

Comparative Example 1 The same amount of antimony trioxide as in Example 1 and the total amount of phosphoric acid added in two portions in Example 1 were added to the first esterification apparatus. The total amount of magnesium acetate added in two portions was added to the first tank of the second esterification apparatus, and polycondensation was carried out under the same conditions as in Example 1 to obtain a prepolymer having an IV of 0.53. Obtained. This was subjected to solid-phase polymerization using the same solid-phase polymerization equipment as in Example 1 under the same conditions, and had an IV of 0.74 and a DEG content of 3.8.
PET with mol%, AA content of 4.7 ppm, cyclic trimer content of 0.34% by weight, and density of 1.398 g / cm ³
A resin was obtained. Molding was performed in the same manner as in Example 1, and the haze was measured. The values were as high as 4.7% and 8.9%, and the transparency was very poor. The heat treatment of the molded plate was performed in the same manner as in Example 1, and the density was measured. The density was 1.341 g / cm ³ when heated at 140 ° C. for 60 seconds, and the density rise rate at 140 ° C. was 1.9 ×. 10 ^-3 (g / (cm ³ · second)), and the density when heated at 180 ° C. for 20 seconds is 1.342.
g / cm ³ , the density increasing rate at 180 ° C. is 4.7 × 10
^-3 (g / (cm ³ · second)).

[0063]

The polyester resin of the present invention is inexpensive,
It can be advantageously used as a molded product having excellent transparency and dimensional stability under heat.

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Claims (5)

[Claims] 1. A molded article which is a polyester resin whose main repeating unit is ethylene terephthalate produced by using an antimony compound and a titanium compound and / or a germanium compound as a catalyst, and which is stretched by a method specified in the text. A polyester resin having a haze of 2.0% or less and a haze of a molded article stretched and heat-fixed by a method specified in the text is 5.0% or less. 2. (a) The density of an amorphous molded article molded from the polyester resin, when heated at 140 ° C. for 60 seconds, is 1.338 (g / cm ³ ) or less, and the density rises at 140 ° C. The speed is 0.2 × 10 ^{−3 to} 0.6 × 10 ⁻³ (g /
(Cm ³ · second)), and (b) the density when the amorphous molded body is heated at 180 ° C. for 20 seconds is 1.3.
38 (g / cm ³ ) or less and the density increasing rate at 180 ° C. is 0.8 × 10 ^{−3 to} 3.0 × 10 ⁻³ (g / (cm ³⁾
2) The polyester resin according to claim 1, which is in the range of). 3. An intrinsic viscosity of 0.70 to 0.90 dl /
g, the amount of copolymerized DEG is 1.5 to 1.5 of the glycol component.
The polyester resin according to claim 1, wherein the polyester resin has 5.0 mol% and a density of 1.37 g / cm ³ or more. 4. The polyester resin according to claim 1, wherein the acetaldehyde content is 10 ppm or less and the cyclic trimer content is 0.35% by weight or less. 5. The polyester resin according to claim 1, wherein said polyester resin is for a hollow molded article.