JP2001233948A - Polyester for blow molded article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester which can efficiently produce a blow molded article, especially a small-size one, excellent in clarity and in dimensional stability under heating, hardly stains a metal mold, and is excellent in long-time continuous moldability and a blow molded article produced therefrom. SOLUTION: This polyester contains ethylene terephthalate units as the main repeating units. The number of spherulites formed when a molded article obtained by melt molding the polyester is subjected to temperature-rise crystallization is in the range of 2×109-20×109/m2, and the haze of the molded article is 10% or lower.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester suitably used as a material of a hollow molded article such as a beverage bottle and a hollow molded article comprising the same. The present invention relates to an excellent small hollow molded article. Further, the present invention relates to a polyester for a hollow molded article having good releasability from a heat treatment mold when molding a small hollow molded article and having excellent long-term continuous moldability.

[0002]

2. Description of the Related Art Polyesters whose main repeating unit is ethylene terephthalate (hereinafter sometimes abbreviated as PET) have excellent transparency, mechanical strength and heat resistance.
Depending on the properties such as gas barrier properties, carbonated beverages, juices,
It is used as a material for containers such as mineral water, and its use has been remarkable. In these applications, polyester bottles are hot-filled with beverages that have been sterilized at high temperatures, or beverages are sterilized at high temperatures after filling, but ordinary polyester bottles shrink during such hot-filling processes. However, deformation occurs and becomes a problem. As a method for improving the heat resistance of the polyester bottle, a method has been proposed in which the crystallinity is increased by heat-treating the bottle cap portion, or the stretched bottle is heat-fixed. In particular, if the plug portion is insufficiently crystallized or has a large variation in crystallinity, the sealing performance with the cap is deteriorated, and the contents may leak.

[0003] In the case of beverages that require hot filling, such as fruit juice beverages, Wurong tea and mineral water, the plug portion of the preform or molded bottle is heat treated to crystallize. (Methods described in JP-A-55-79237, JP-A-58-110221, etc.) are generally used. Such a method, that is, a method of improving the heat resistance by heat treatment of the plug portion and the shoulder portion, the time and temperature for the crystallization treatment greatly affect the productivity, and the crystal can be processed at a low temperature and in a short time. It is preferable that the PET is a PET having a high conversion rate. 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 contents of the bottle, and the plug and the body need to have contradictory characteristics.

In order to improve the heat resistance of the body of the bottle, a method of performing heat treatment at a high temperature of a drawing blow mold as disclosed in Japanese Patent Publication No. 59-6216, for example, is adopted. However, when a large number of bottles are continuously formed using the same mold by such a method, the bottle obtained with a long operation is whitened, the transparency is reduced, and only a bottle having no commercial value can be obtained. . It was found that this was due to the attachment of the PET-derived material to the mold surface, resulting in mold stains, and the mold stains being transferred to the bottle surface. In particular, in recent years, the molding speed has been increased along with the miniaturization of bottles, and from the viewpoint of productivity, the shortening of the heating time for crystallization of the plug and the contamination of the mold have become more serious problems. .

[0005]

Various proposals have been made to solve such a problem. For example, a method of adding an inorganic nucleating agent such as kaolin or talc to polyethylene terephthalate (JP-A-56-2342, JP-A-56-21832), or an organic nucleating agent such as a montanic acid wax salt. Although there is a method of adding (JP-A-57-125246 and JP-A-57-207639), these methods have a problem in practical use due to generation of foreign matters and cloudiness. Also, a method of inserting a heat-resistant resin piece into the plug (Japanese Patent Application Laid-Open No. 61-259946, Japanese Patent Application Laid-Open
No. 69638), but the productivity of bottles is poor and there is a problem in recyclability.

[0006] Further, the crystallization temperature at the time of raising the temperature of the flakes collected from the center of the PET chip, and after melting the flakes,
PET in which the number of spherulites and the like in the case of isothermal crystallization at 200 ° C. are regulated, and a hollow molded body therefrom (Japanese Patent No.
No. 29) has been proposed, but since the effect of promoting crystallization of the chip surface layer and the effect of promoting the crystallization of PET fine particles coexisting with the chip are extremely large, only the crystallization characteristics of the chip central portion as described in the above patent are disclosed. Is insufficient to obtain a hollow molded article having good transparency, which is a problem.

The present invention solves the above-mentioned conventional problems, and can efficiently produce a hollow molded article having excellent transparency and heat-resistant dimensional stability, particularly a small hollow molded article, by high-speed molding. It is an object of the present invention to provide a polyester excellent in long-term continuous moldability and a hollow molded article made of the same, which does not contaminate it.

[0008]

In order to achieve the above object, the polyester of the present invention is a polyester whose main repeating unit is ethylene terephthalate, and is a molded article obtained by melt-molding the polyester. The number of spherulites generated when the temperature is increased is 2 × 10 ^{9 to} 20 × 10 ⁹ / m
² , and the haze of the molded body is 10% or less. Here, the number of spherulites generated in the case of temperature-induced crystallization means the number of spherulites measured by a method described later. The polyester of the present invention having the above constitution can easily obtain a hollow molded article having excellent transparency and heat-resistant dimensional stability, particularly a small hollow molded article, by melt molding. Good partial crystallization,
In addition, it is possible to obtain a polyester which has a crystallization rate at which the shrinkage rate of the plug portion falls within an appropriate range, and is excellent in long-time continuous moldability which does not stain the mold.

[0009] In this case, the crystallization temperature of the molded body obtained by melt-molding the polyester at the time of raising the temperature is from 150 to 16 ° C.
It is characterized by a temperature range of 5 ° C.

In this case, the intrinsic viscosity of the polyester is 0.70 to 0.90 dl / g, and the content of diethylene glycol copolymerized with the polyester is 1.5% of the glycol component constituting the polyester. ５5.0 mol%.

In this case, the density of the polyester is
It can be 1.37 g / cm ³ or more. Also, in this case, the acetaldehyde content can be 10 ppm or less. In this case, the cyclic trimer content can be 0.5% by weight or less. In this case, the amount of increase of the cyclic trimer when melted at a temperature of 290 ° C. for 60 minutes can be 0.30% by weight or less.

In this case, the catalyst may be obtained using a Ge compound and / or a Ti compound as a polycondensation catalyst. Further, in this case, the hollow molded body may be formed by molding the polyester described above.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the polyester of the present invention will be specifically described. The polyester in which the main repeating unit of the present invention is ethylene terephthalate,
It is a linear polyester containing at least 85 mol% of ethylene terephthalate units, preferably at least 90 mol%, more preferably at least 95.0%.

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

Glycols used for copolymerization of the polyester include aliphatic glycols such as diethylene glycol, trimethylene glycol, tetramethylene glycol and neopentyl glycol, and cyclohexane dimethanol. Alicyclic glycols such as -phenol, bisphenol A,
Aromatic glycols such as an alkylene oxide adduct of bisphenol A are exemplified.

Further, other copolymerization components comprising a polyfunctional compound in the polyester include trimellitic acid and pyromellitic acid as acidic components, and glycerin and pentaerythritol as glycol components. Can be cited. The amount of the above-mentioned copolymer component to be used must be such that the polyester maintains a substantially linear shape.

The polyester of the present invention is obtained by directly reacting terephthalic acid with ethylene glycol and, if necessary, the above-mentioned copolymerization component to distill off water and esterify the mixture. Then, as a polycondensation catalyst, an Sb compound, Ge compound or A direct esterification method in which polycondensation is performed under reduced pressure using one or more compounds selected from Ti compounds, or the presence of a transesterification catalyst for dimethyl terephthalate and ethylene glycol and, if necessary, the above copolymerization component The reaction is carried out under reduced pressure to remove the methyl alcohol and transesterify, and then the mixture is subjected to a pressure reduction mainly using one or more compounds selected from Sb compounds, Ge compounds and Ti compounds as a polycondensation catalyst. It is produced by a transesterification method in which condensation is performed. These polymerization catalysts may be added before the start of the transesterification reaction or the esterification reaction or during the reaction.

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 Sb compound is added so that the residual amount of Sb in the resulting polymer is in the range of 50 to 250 ppm.

The Ge compound used in the present invention includes:
Examples include amorphous germanium dioxide, crystalline germanium dioxide, germanium chloride, germanium tetraethoxide, germanium tetra-n-butoxide, and germanium phosphite. When a Ge compound is used, the amount used is 5 to 150 ppm, preferably 10 to 100 ppm, as a Ge residual amount in the polyester resin,
More preferably, it is 15 to 70 ppm.

The Ti compounds used in the present invention include:
Tetraethyl titanate, tetraisopropyl titanate
And tetraalkyl titanates such as tetra-n-propyl titanate and tetra-n-butyl titanate and their partial hydrolysates, 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. The Ti compound is 0.1 to 10 as a residual amount of Ti in the produced polymer.
It is added to be in the range of ppm.

Various P compounds can be used as a stabilizer. Examples of the P compound used in the present invention include 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, methyl phosphonic acid, methyl dimethyl phosphonate, dimethyl ethyl phosphonate, dimethyl phenyl phosphonate, diethyl phenyl phosphonate, diethyl phenyl -Diphosphonic acid diphenyl ester and the like, which may be used alone or in combination of two or more. The P compound can be added at any stage of the polyester production reaction step so that the residual amount of P in the produced polymer is in the range of 5 to 100 ppm. Further, solid-state polymerization may be performed to increase the intrinsic viscosity of the polyester and reduce the acetaldehyde content.

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

The shape of the polyester chip may be any of a cylinder type, a square type, a flat plate shape and the like, and the size thereof is usually 1.6 to 3.5 in height, width and height, respectively.
mm, preferably in the range of 1.8 to 3.5 mm. For example, in the case of a cylinder type, the length is 1.8 to 3.5 m
It is practical that m and the diameter are about 1.8 to 3.5 mm. Further, the weight of the chip is practically in the range of 15 to 30 mg / piece.

In the above-mentioned manufacturing process, in the step of forming the melt polycondensation polymer into chips, the solid phase polymerization step, the water treatment step, the step of transporting the melt polycondensation polymer chips or the solid phase polymerization polymer chips, etc. In addition, particles, powders, and the like, which are considerably smaller than chips having the size originally set at the time of granulation, are generated. Here, such a fine granular material or powder is referred to as fine. In the process for producing the polyester of the present invention, raw materials and auxiliary materials having high purity are used, and a melt polycondensation polymer is used.
Filtration of cooling water of polyester chips, filtration of water introduced from outside the system for water treatment of chips, filtration of gas used for transporting the chips, etc., so that foreign substances and impurities other than polyester used are not mixed. Implement various measures,
The fines can be made free of foreign matter and contaminants other than polyester.

The polyester of the present invention is a polyester whose main repeating unit is ethylene terephthalate, and a test piece from a molded product having a thickness of 3 mm obtained by melt-molding the polyester was heated and crystallized. The number of spherulites generated in the case is in the range of 2 × 10 ^{9 to} 20 × 10 ⁹ / m ² ,
The molded product having a thickness of 5 mm has a haze of 10% or less, preferably a spherulite number in the range of 2.5 × 10 ⁹ to 18 × 10 ⁹ / m ² , and a haze of 9% or less, more preferably a spherulite. The number is in the range of 3.0 × 10 ⁹ to 15 × 10 ⁹ pieces / m ² , and the haze is 8% or less.

When manufacturing a heat-resistant polyester hollow molded article, the plug section is uniformly crystallized so that the plug section is not deformed or shrunk when filling a high-temperature beverage, and the hollow section is formed after stretch blow molding. The body is heat-treated and crystallized to improve heat resistance so that the body of the hollow molded body is not deformed during filling of high-temperature beverage or high-temperature sterilization. As described above, it is necessary that the polyester for a hollow molded article has an appropriate crystallization rate and, at the same time, has crystallization characteristics capable of securing transparency by heat setting after stretching. Polyesters with the above properties are suitable for such purposes.

[0027] If the TamaAkirasu does not reach 2 × 10 ⁹ cells / m ^2, when heat-treating the hollow molded body spout portion, slow heating crystallization speed, processing up to achieve a constant degree of crystallinity The time gets longer. As a result, the productivity of the hollow molded body deteriorates,
This is a problem particularly when molding small compacts. In addition, the mold is heavily soiled at the time of stretching heat fixing performed to improve heat resistance, and the mold must be cleaned frequently to obtain a transparent hollow molded body. When the number of spherulites exceeds 20 × 10 ⁹ / m ² , the crystallization speed is increased, and the crystallization of the plug portion of the hollow molded article becomes excessive. Therefore, the shrinkage amount of the plug portion is regulated. Since it does not fall within the value range, the capping of the plug portion becomes defective, causing leakage of the contents, and the transparency of the heat-resistant hollow molded article is reduced, which is a problem.

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

Further, the polyester of the present invention may be a hollow molded article having a thickness of 5 mm obtained by melt-molding the polyester and having a haze of 10% or less and a haze of more than 10%. Is poor, and this is a problem particularly in the case of a stretched hollow molded article.

The polyester of the present invention has a crystallization temperature (hereinafter referred to as "Tc1") at the time of raising the temperature of a test piece from a 2 mm-thick molded body obtained by melt-molding the polyester.
Is in the range of 150 to 165C, preferably 152 to 163.
C, more preferably in the range of 155 to 160C. If Tc1 exceeds 165 ° C., the heating crystallization rate becomes extremely slow, and the effect of improving crystallization cannot be expected.
When Tc1 is less than 150 ° C., the transparency of the hollow molded article is reduced, which is problematic.

The polyester of the present invention can be produced, for example, by the following method. That is, 0.1 ppm of polyacetal is dispersed in a polyester having an average dispersed particle size of 10 μm or less, preferably 5 μm or less.
b to 100 ppm, and the fines described above are contained in an amount of 0.1 ppm.
It can be manufactured by containing 1 to 300 ppm. Polyacetal acts as a nucleating agent for crystallization of polyester and has the effect of increasing the rate of heat crystallization of the polyester hollow molded article.However, the crystallization rate of the polyester hollow molded article is further increased, and the polyester crystallization is performed uniformly. For this purpose, it is important to disperse the polyacetal so that the average dispersed particle size is 10 μm or less. The content of polyacetal dispersed in an average dispersed particle size of 10 μm or less is less than 0.1 ppb, and the content of fine is 0.
When the content is less than 1 ppm, the number of spherulites generated at the time of temperature-rising crystallization is 2 × 10 ⁹ / m ² or less. The average dispersed particle size is 1
When the content of polyacetal dispersed in 0 μm or less exceeds 100 ppm and the content of fine is 300 p
If it exceeds pm, the number of spherulites generated at the time of temperature-rising crystallization exceeds 20 × 10 ⁹ / m ^2, and the transparency of the obtained molded body is deteriorated.

The polyacetal used in the present invention includes a polyacetal homopolymer or a polyacetal copolymer. ASTM-D79 is a polyacetal homopolymer used in the present invention.
The density measured by the measuring method of No. 2 is 1.40 to 1.42 g.
/ Cm ³ , 19 according to ASTM D-1238.
Polyacetal having a melt index (MI) measured at 0 ° C. and a load of 2160 g in the range of 0.5 to 50 g / 10 minutes is preferred.

The polyacetal copolymer has a density of 1.38 to 1.43 g / cm ^{3 as} measured by ASTM-D792, and ASTM D-1238.
A polyacetal copolymer having a melt index (MI) measured at 190 ° C. under a load of 2160 g in the range of 0.4 to 50 g / 10 minutes according to the above measuring method is preferred. These copolymerization components include ethylene oxide and cyclic ether.
Tell.

As a method for dispersing the polyacetal in the polyester so as to have an average dispersed particle size of 10 μm or less, for example, the following method can be mentioned. That is, polyacetator
Is added prior to melt polycondensation, then polycondensed to a predetermined intrinsic viscosity and then filtered in a molten state through a filter having a pore size of 10 μm.
A method of kneading and extruding with a screw extruder to prepare a high-concentration master batch in which the dispersed particle size of polyacetal in the kneaded composition is 10 μm or less, and adding the same during melt polycondensation to perform polycondensation, Alternatively, there is a method in which the master batch is blended with polyester before molding and molded.

The above-mentioned fine polyester is a fine having a particle size passing through a standard sieve having a nominal size of 1.7 mm according to JIS-Z8801, preferably a nominal size of 0 according to JIS-Z8801. .
Fine particle size fine enough to pass through a 71 mm standard sieve.

In the present invention, as a method for adjusting the fine content of the polyester to the above-mentioned range, a high fine polyester chip which has not been subjected to the sieving step is subjected to a sieving step and a fine removing step by an air flow. In addition to the method of mixing the polyester chips having a very small fine content at an appropriate ratio, it can also be adjusted by changing the size of the sieve in the fine removal step, and by changing the sieving speed, etc. Any method can be used.

The polyester of the present invention can also be produced by the following method when the polyester chips are treated with water as described below. That is, first, in the water treatment step, it is preferable that at least a part of the water to be treated is water that is discharged from the treatment tank, returned to the treatment tank again, and used repeatedly. By reusing water, it is possible to control the amount of fine powder in the treated water, and it is easy to control the fine content of the polyester. When water having a fine powder amount of 0 is used for water treatment, fines adhering to the polyester chips may be washed away by water and may fall below 0.1 ppm.

Further, the amount of fine powder in the treated water is 1000 pp.
It is preferable to perform the treatment while adjusting the pressure to m or less.
If water having a fine powder amount exceeding 1000 ppm is used, the fine content of the polyester may exceed 500 ppm.

The intrinsic viscosity of the polyester chip of the present invention is preferably 0.70 to 0.90 deciliter / gram, more preferably 0.71 to 0.87 deciliter / gram. If the intrinsic viscosity of the polyester chips is less than 0.70 deciliter / gram,
The transparency, heat resistance, mechanical properties, and the like of the hollow molded article obtained by melt-molding the polyester of the present invention may not be sufficiently satisfied. On the other hand, when the intrinsic viscosity is larger than 0.90 deciliter / gram, heat generation at the time of molding becomes intense, so that coloring of the hollow molded article becomes intense, and the content of acetaldehyde (hereinafter sometimes referred to as AA) is reduced. It tends to increase and becomes unsuitable for food applications such as beverage bottles.

The copolymerized diethylene glycol (DEG) content of the polyester of the present invention is in the range of 1.0 to 5.0 mol% of the glycol component constituting the polyester, and preferably 1.5 to 5.0 mol%. To 4.8 mol%, more preferably 2.0 to 4.5 mol%. When the content is less than 1.0 mol%, the transparency of the obtained hollow molded article becomes extremely poor,
On the other hand, when the content exceeds 5.0 mol%, the stability of thermoforming is inferior, and the AA content of the obtained hollow molded article becomes extremely high, so that the flavor of the content deteriorates.

The polyester of the present invention may contain a small amount of cyclic trimer, but the content thereof is 0.5% by weight or less, preferably 0.45% by weight or less, more preferably 0.40% by weight. It is as follows. When a heat-resistant hollow molded article is molded from the polyester of the present invention, heat treatment is performed in a heating mold. However, when the content of the cyclic trimer exceeds 0.5% by weight, the heat is applied to the surface of the heating mold. Is rapidly increased, and the transparency of the obtained hollow molded article is extremely deteriorated.

The polyester of the present invention has a temperature of 290 ° C.
The amount of increase of the cyclic trimer when melted at a temperature of 60 minutes for not more than 0.30% by weight, preferably not more than 0.20% by weight,
More preferably, the content is 0.10% by weight or less. When hollow molding is performed using polyester whose cyclic trimer increase amount exceeds 0.30% by weight, oligomers such as cyclic trimers adhere to the inner surface of the mold, the gas exhaust port and the exhaust pipe of the mold. In order to obtain a transparent hollow molded body, the mold must be frequently cleaned.

The polyester of the present invention, in which the amount of the cyclic trimer increased by 0.30% by weight or less when melted at a temperature of 290 ° C. for 60 minutes, is obtained from the polyester obtained after melt polycondensation or solid state polymerization. It can be produced by deactivating the polycondensation catalyst. Examples of the method for deactivating the polyester polycondensation catalyst include a method of subjecting a polyester chip to contact treatment with water, steam or a steam-containing gas after melt polycondensation or after solid-phase polymerization.

Examples of the hot water treatment method include a method of immersing in water and a method of spraying water on a chip with a shower. The treatment time is 5 minutes to 2 days, preferably 10 minutes to 1 day, more preferably 30 minutes to 10 hours, and the water temperature is 20 to 180 ° C, preferably 40 to 150 ° C.
° C, more preferably 50 to 120 ° C.

The following is an example of a method for industrially performing water treatment, but the method is not limited thereto. The treatment method may be either a continuous method or a batch method, but the continuous method is preferable for industrial use.

In the case of treating the polyester chips with water in a batch system, a silo-type treatment tank may be used. That is, the chips of the polyester are received in the silo in a batch system and water treatment is performed. Alternatively, it is also possible to receive the polyester chips in a rotary cylindrical treatment tank and perform water treatment while rotating the chips to make the contact with water more efficient.

In the case of treating the polyester chips with water in a continuous manner, the polyester chips can be continuously or intermittently received from above in a tower-type treatment tank and subjected to water treatment.

When the polyester chips are brought into contact with water vapor or a gas containing water vapor for treatment, 50 to 15
Steam or steam-containing gas or steam-containing air at a temperature of 0 ° C., preferably 50 to 110 ° C., is preferably supplied in an amount of 0.5 g or more as steam per 1 kg of the granular polyester, or is present in the particulate polyester and steam. And contact.

The contact between the polyester chips and water vapor is usually performed for 10 minutes to 2 days, preferably for 20 minutes to
Performed for 10 hours.

The following is an example of a method for industrially carrying out the contact treatment between the granular polyester and steam or a steam-containing gas, but the method is not limited thereto. The processing method may be either a continuous method or a batch method.

In the case where the polyester chips are subjected to a contact treatment with steam in a batch system, a silo-type treatment apparatus may be used. That is, a polyester chip is received in a silo, and steam or a steam-containing gas is supplied in a batch system to perform a contact treatment. Alternatively, it is also possible to receive the granular polyester in a rotary cylinder type contact treatment device and perform the contact treatment while rotating the contact polyester, thereby making the contact more efficient.

When the polyester chips are continuously subjected to the contact treatment with steam, the granular polyester is continuously received from the top in a tower-type treatment apparatus, and the steam is continuously supplied in parallel or countercurrent to carry out the contact treatment with the steam. .

As an example of the hot water treatment method for polyester chips, the following method can be mentioned. That is, the polyester formed into chips after the polycondensation is treated with treated water containing waste water returned from the treatment tank at a temperature of 40 in the hot water treatment tank.
To 120 ° C. Also,
There is also a method in which wastewater discharged together with chips from the treatment layer is treated in the same temperature range without returning to the treatment layer.
In addition, polyester formed into chips after polycondensation,
In the treatment tank, the content of the polyester fine powder is 10
There is also a method of treating with treated water of 00 ppm or less. In addition,
The fine powder referred to here is a fine polyester powder coexisting together with the chips in the water treatment layer.
〜1300 μm.

As described above, when treated with water or steam, the granular polyester is drained by a draining device such as a vibrating sieve or a simmon cutter, if necessary, and transferred to the next drying step.

For drying the polyester chips which have been subjected to the contact treatment with water or steam, a commonly used polyester drying treatment can be used. As a method for continuous drying, a hopper-type through-air dryer that supplies a polyester chip from the upper portion and allows a drying gas to flow from the lower portion is usually used. As a method for reducing the amount of drying gas and drying efficiently, a rotary disk-type continuous dryer is used. Heating steam, heating medium, etc. are supplied to the rotating disk and the outer jacket while passing a small amount of drying gas. The polyester chips can be indirectly heated and dried.

As a dryer for drying in a batch system, a double cone type rotary dryer is used, which can be dried under vacuum or while passing a small amount of drying gas under vacuum. Alternatively, the drying may be performed while passing a drying gas under atmospheric pressure.

As the dry gas, atmospheric air may be used, but dry nitrogen and dehumidified air are preferred from the viewpoint of preventing molecular weight reduction due to hydrolysis or thermal oxidative decomposition of polyester.

By subjecting the polyester to water or steam treatment as described above, the solid phase polycondensation rate of the polyester is reduced, and the amount of oligomer increase after heating and melting the polyester at a temperature of 290 ° C. is suppressed. be able to.

It is also possible to simultaneously use saturated fatty acid monoamides, unsaturated fatty acid monoamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides and the like with the polyester of the present invention.

Examples of the saturated fatty acid monoamide include lauric amide, palmitic amide, stearic amide, behenic amide and the like. Examples of unsaturated fatty acid monoamides include oleic acid amide, erucic acid amido ricinoleic acid amide, and the like. Examples of the saturated fatty acid bisamide include methylene bisstearic acid amide, ethylenebiscapric acid amide, ethylenebislauric acid amide, ethylenebisstearic acid amide, ethylenebisbehenic acid amide, hexamethylenebisstearic acid amide, hexamethylenebisbehenic acid Amides and the like. Examples of the unsaturated fatty acid bisamide include ethylene bisoleic acid amide and hexamethylene bisoleic acid amide. Preferred amide compounds are saturated fatty acid bisamide, unsaturated fatty acid bisamide and the like. The compounding amount of such an amide compound is 1
The range is from 0 ppb to 1 × 10 ⁵ ppm.

Metal salt compounds of aliphatic monocarboxylic acids having 8 to 33 carbon atoms, such as naphthenic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid,
Stearic acid, behenic acid, montanic acid, melicic acid,
Lithium, sodium, potassium, magnesium, calcium, and cobalt salts of saturated and unsaturated fatty acids such as oleic acid and linoleic acid can be used in combination. The compounding amount of these compounds is 10p
The range is from pb to 300 ppm.

The polyester of the present invention can be preferably used as a resin for a hollow molded article. Further, the polyester of the present invention can also be used as one constituent layer such as a multilayer molded article.

The polyester of the present invention may contain various additives such as known UV absorbers, lubricants, release agents, nucleating agents, stabilizers, antistatic agents and pigments, if necessary.

[0064]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to these Examples.
The main method of measuring characteristic values in the present invention will be described below.

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

(2) Diethylene glycol content (hereinafter referred to as "DEG content") Decomposed with methanol, the DEG content is determined by gas chromatography, and the ratio (mol%) to the total glycol components is determined. expressed.

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

(4) Content of Polyester Cyclic Trimer (CT Content) A sample is dissolved in a mixed solution of hexafluoroisopropanol / chloroform, and further diluted with chloroform. After adding methanol to precipitate a polymer, the mixture is filtered. The filtrate was evaporated to dryness, made up to a constant volume with dimethylformamide, and a cyclic trimer composed of ethylene terephthalate units was quantified by liquid chromatography.

(5) Increase in amount of cyclic trimer during melting of polyester (ΔCT amount) 3 g of dried polyester chip was placed in a glass test tube, immersed in an oil bath at 290 ° C. for 60 minutes under a nitrogen atmosphere, and melted. Let it. The amount of increase of the cyclic trimer at the time of melting is determined by the following equation. Cyclic trimer increase during melting (% by weight) = Cyclic 3 after melting
Monomer content (% by weight) -cyclic trimer content before melting (% by weight)

(6) Measurement of Fine Content Using a standard sieve having a nominal size of 1.7 mm according to JIS-Z8801, a 1000 kg sample is sieved, and the weight of the fine that has passed through the sieve is weighed to determine the content.

(7) Density of Polyester Chip and Molded Plate The density was measured at 30 ° C. using a density gradient tube of a calcium nitrate / water mixed solution.

(8) Haze (% haze) A sample was cut from the body (thickness: about 0.4 mm) of the molded article (thickness: 5 mm) and the hollow molded article (14) below, and Measured with a haze meter manufactured by Denshoku Co., Ltd.

(9) Number of spherulites at the time of temperature-induced crystallization of the molded body A test piece having a size of 8 mm × 10 mm was cut out from a 3 mm thick plate portion from the stepped molded plate of the following (12) and used as a measurement sample. . The formed plate has a molecular orientation derived from the flow at the time of forming, but the orientation state varies depending on the portion of the formed plate. Therefore, the molded plate is sandwiched between two polarizing plates whose polarizing planes are orthogonal to each other, and the orientation is observed by observing the intensity distribution of light transmitted through the molded plate when irradiating visible light from a direction perpendicular to the polarizing plate surface. I checked the status. A test piece was cut out from a portion where the molecular dimensions did not include non-uniformity of molecular orientation (such as the degree of orientation and fluctuation of the orientation direction).

At this time, the orientation of the optical anisotropy is confirmed in advance, and the relationship with the orientation of the test piece to be cut out is as follows. The orientation of the optical anisotropy was determined by a method described in New Polymer Experimental Science 6 Polymer Structure (2) (Kyoritsu Shuppan Co., Ltd.) using a polarizing microscope and a sensitive color plate. The test piece was cut out so that the direction of the axis having a small refractive index (the axis at which the speed of light was high) was parallel to the long axis of the test piece. Alignment disorder and cut surface irregularities introduced when cutting a test piece significantly affect the measurement results. Therefore, the unevenness of the cut surface and the portion with disordered orientation were removed using a cutter to obtain a flat surface. The density of the test piece and the degree of molecular orientation also affect the results. The values of density and birefringence are 1.3345 to 1.3355, respectively.
g / cm ³ and 1.30 × 10 ^{−4 to} 1.50 × 10 ⁻⁴ . The density was measured using a water-based density gradient tube with a resin sampled from the vicinity of the test piece sampling site as a sample. Birefringence is measured using a polarizing microscope (Nikon EC
(LIPSE E600 POL) using the Berek compensator method. As the measured value, the value obtained at the center of the test piece was adopted. The test piece prepared as described above was
Heat treatment was performed with a thermomechanical analysis (TMA), type TMA 4000S, manufactured by Mac Science. Under a constant compressive load of 0.2 g and an Ar atmosphere, from room temperature to 210 ° C., 27 ° C. /
The temperature was raised at a rate of min., kept at 210 ° C. for 180 seconds, then lowered to a room temperature at a rate of 47 ° C./min., and the number of spherulites was measured by the following method.

Using a microtome RM2065 manufactured by Leica, a section having a thickness of 2 μm is prepared from the end of the test piece. This section is observed using a Nikon polarizing microscope ECLIPSE E600POL. Observation is performed using halogen lamp light as a light source, and monochromaticity is not performed using an interference filter or the like. The optical system is adjusted to a so-called crossed Nicols state in which the optical axes of the polarizer and the analyzer are orthogonal to each other, and a 530-nm sensitive color detector is inserted into the optical path. The image was taken by a color CCD camera (HITACH
I HV-C205) and save it as a still image on a Macintosh computer via an image capture board.

Observing the section with the above optical system,
Numerous spherulites are observed. When a 530 nm sensitive color plate is inserted into the optical path and observed, the spherulite shows symmetry reflecting the orientation of the optical anisotropy inside. Specifically, the spherulite is observed as if it were divided into four with its center symmetric. The sensitive color plate shows different colors in a direction parallel to and a direction perpendicular to the axis having a low refractive index (parallel to the insertion direction). This color is the interference color when the retardation caused by the test plate increases by the sample, and the interference color when the retardation decreases, conversely, the direction of the optical axis of the inserted test plate and the optical color inside the spherulite. It is determined by the relationship of the anisotropic orientation.

Using a CCD camera, 105 μm × 79
Photograph an area of μm and save it on a computer recording device (hard disk, magneto-optical disk, etc.).
From this image, the number of spherulites is counted on a Macintosh computer using the image processing software Ultimage / Pro (Image and Measurement Co., Ltd.) according to the following procedure. As described above, the spherulite has two colors. The threshold level is set so that only one of the colors remains, and binarization is performed. With this operation, only the portion having one color is measured. In addition, Primary Morp
Set Erosion in the hology menu to Number of integrations = 1
Run with By this operation, portions which are connected to each other despite being originally belonging to different spherulites are separated. After performing this operation, execute the Particle menu and read the value of Detected particles. At this time,
Particles with an area less than 4 pixels are not measured. Since two particles are measured per spherulite, the value obtained by dividing the value of the detected particles read earlier by 2 is used as the number of spherulites.

(10) The crystallization temperature (T
c1) Differential thermal analyzer (DS) manufactured by Seiko Electronics Co., Ltd.
C), measured with RDC-220. A 10 mg sample from the center of a plate having a thickness of 2 mm of the following molded plate (12) was used. The temperature was raised at a rate of temperature rise of 20 ° C./min, and the apex temperature of the crystallization peak observed in the course of the heating was measured and defined as the crystallization temperature at the time of temperature rise (Tc1).

(11) Density increase due to heating of the bottle cap The bottle cap was heat-treated for 60 seconds with a homemade infrared heater, and a sample was taken from the top to measure the density.

(12) Molding of Stepped Molded Plate The dried polyester was dried with a Meiki Seisakusho M-150C (D
M) Molding is performed by an injection molding machine at a cylinder temperature of 290 ° C. using a stepped flat mold cooled to 10 ° C. The resulting stepped plates were 2, 3, 4, 5, 6, 7, 8,
A plate of about 3 cm x about 5 cm square with a thickness of 9, 10 and 11 mm is provided in a stepwise manner, and the weight of one piece is about 146
g. A plate having a thickness of 2 mm is used for measuring the density rise rate and Tc1, a plate having a thickness of 3 mm is used for measuring the number of spherulites, and a plate having a thickness of 5 mm is used for measuring haze (haze percentage).

(13) Measurement of average dispersed particle size of polyacetal Polyester chips were dissolved in hexafluoroisopropanol (about 1% concentration), and the insoluble matter was filtered through a 0.2 μm membrane filter. Take a photograph and measure the particle size. The average value of 10 polyacetal particles on the filter is determined.

(14) Evaluation of mold stain The polyester was dried by a dryer using dehumidified air, and a preform was molded at a resin temperature of 290 ° C. by an M-150C (DM) injection molding machine manufactured by Meiki Seisakusho. . This preform
After heating and crystallizing the plug portion of the system with a home-made plug portion crystallizer, biaxially stretched blow molding was performed using an LB-01 stretch blow molding machine manufactured by Co-Poplast Co., Ltd.
Was heat-set in a mold set for 7 seconds to obtain a 350 cc hollow molded body. The haze of the body of the hollow molded body in which the molding is in a steady state is measured. Under the same conditions, stretch blow molding was continuously performed, and the stain on the mold was evaluated by the number of moldings until the transparency of the molded article was impaired by visual judgment. Further, as a sample for haze measurement, a body portion of a molded body after continuous molding 5,000 times was provided.

(15) Evaluation of Leakage of Contents from Hollow Molded Body The hollow molded body molded in the above (14) is filled with hot water at 90 ° C., capped by a capping machine, and the molded body is turned down and left The contents were leaked. The deformation of the plug after capping was also examined.

(Example 1) A slurry of high-purity terephthalic acid and ethyl glycol was continuously supplied to a first esterification reactor containing a reactant in advance, and stirred for about 2 hours.
The reaction was carried out at 50 ° C. and 0.5 kg / cm 2 G for an average residence time of 3 hours. This reaction product was sent to the second esterification reactor, and reacted at a temperature of about 260 ° C. and 0.05 kg / cm 2 G to a predetermined degree of reaction with stirring. In addition, crystalline germanium dioxide is dissolved in water by heating, ethylene glycol is added thereto, and a heat-treated catalyst solution and a phosphoric acid ethylene glycol solution are separately and continuously supplied to the second esterification reactor. did. This esterification reaction product is continuously supplied to the first polycondensation reactor, and is stirred at about 265 ° C. and 25 t
at 265 ° C., 3 torr for 1 hour while stirring in the second polycondensation reactor, and about 275 ° C. for 1 hour at 0.5 to 1 torr while stirring in the final polycondensation reactor. Was. In a mixer installed after the final polycondensation reactor, polyacetal (MI = 1.0 g / 10 min, density =
A molten PET master in which 1.41 g / cm ³ ) was dispersed so as to have an average dispersed particle size of 5 μm or less was mixed so as to have the addition amount shown in Table 1, and the resulting mixture was formed into chips. IV of PET obtained
Was 0.54 and the DEG content was 2.6 mol%. A PET master (polyacetal, about 100 ppm) in which polyacetal is finely dispersed is obtained by kneading dry PET and the polyacetal powder with a twin-screw extruder, and forming a sintered metal having pores of about 5 μm. After passing through a filter, the mixture is pelletized, and the average dispersion diameter of polyacetal is measured.
m or less. The PET chip was subsequently crystallized at about 155 ° C. under a nitrogen atmosphere, further preheated to about 200 ° C. under a nitrogen atmosphere, and then sent to a continuous solid-state polymerization reactor to undergo solid-state polymerization at about 205 ° C. under a nitrogen atmosphere. After the solid phase polymerization, the mixture was continuously treated in a sieving step and a fine removing step to obtain PET shown in Table 1.

The intrinsic viscosity of the obtained PET was 0.74 deciliter / gram, the content of the cyclic trimer was 0.37% by weight, the increase in the cyclic trimer was 0.39% by weight, and the density was 1.4.
The content of AA was 00 g / cm ³ and the content of AA was 2.9 ppm. The residual amount of Ge measured by atomic absorption analysis was 47 ppm, and the residual amount of P was 35 ppm. In addition, the obtained PE
The number of spherulites of the formed plate of T is 3.5 × 10 ⁹ / m ² , Tc1
Was 163.2 ° C., the haze of the formed plate was 3.0%, and the average dispersed particle size of polyacetal was 5 μm. This PET was evaluated using a biaxially stretched bottle. Table 1 shows the results. The density of the spout was 1.375 g / cm ^3, which was a satisfactory value. Although continuous stretch blow molding of 5,000 or more pieces was performed, no stain on the mold was observed and the transparency of the bottle was good. Was. Also, there was no problem in the leakage test of the contents. The barrel haze of the obtained bottle was as good as 0.6%. In addition, the number of times of molding up to mold contamination was 11,000, which was no problem. The AA content of the bottle was 15.7 ppm, which was a satisfactory value.

(Example 2) Melt polycondensation and solid phase polymerization were carried out in the same manner as in Example 1 except that the amount of the PET master was changed, and PET was obtained by changing the fine removal ability. As shown in Table 1, the number of spherulites of the obtained PET molded plate was 9.6 × 10 ⁹ / m ² , Tc1 was 158.1 ° C., the molded plate haze was 4.1%, and the polyacetal had a The average dispersed particle size was 5 μm. The density of the bottle cap is 1.377
g / cm ³ , which is a value that is not a problem, and continuous stretch blow molding of 5,000 or more was carried out, but no mold stains were observed and the transparency of the bottle was good. Also, there was no problem in the leakage test of the contents. The barrel haze of the obtained bottle was as good as 1.0%. In addition, the number of moldings up to the mold contamination was 13,000, which was no problem.

(Example 3) Polycondensation was carried out in the same manner as in Example 1 except that the amount of polyacetal added was changed, and PET having a fine content of 0.1 ppm or less was obtained by enhancing the fine removing ability. . The IV of PET was 0.74 deciliter / gram, the content of cyclic trimer was 0.34% by weight,
DEG content is 2.8 mol%, AA content is 3.1 pp
m, and the density was 1.400 g / cm ³ . This P
The ET chips were treated with hot water. The apparatus shown in FIG. 1 is used for the water treatment of the polyester chips. The raw material chip supply port (1) at the upper part of the treatment tank, the overflow outlet (2) located at the upper limit level of the treated water in the treatment tank, An outlet (3) for a mixture of polyester chips and treated water at the bottom of the treatment tank, treated water discharged from this overflow outlet, treated water discharged from the treatment tank, and discharge at the bottom of the treatment tank. The treated water discharged from the section through the draining device (4) is used as the filter medium made of paper.
A pipe (6) sent again to the water treatment tank via a fine particle removing device (5) which is a continuous filter of 0 μm, an inlet (7) for the treated water from which fine particles have been removed, An adsorption tower (8) for adsorbing acetaldehyde, and a tower-type treatment tank having an internal capacity of about 500 liters equipped with a new ion-exchanged water inlet (9) were used.
50 to a water treatment tank controlled at a treated water temperature of 95 ° C
At a rate of kg / hour, the water is continuously charged from the supply port (1) at the upper part of the processing tank, and PE is discharged from the outlet (3) at the lower part of the processing tank in a water treatment time of 4 hours using treated water having a fine powder content of about 200 ppm.
T chips were continuously extracted together with the treated water at a rate of 50 kg / hour. The fine content of the obtained PET was about 100 ppm. The amount of fine powder in the treated water is
JIS standard (JIS-Z-8)
801), 1000 ml of treated water passed through a filter having a nominal size of 850 μm was collected, and 1G1 manufactured by Iwaki Glass Co., Ltd. was collected.
After filtration with a glass filter (pores 100 to 120 μm), the mixture is dried at 100 ° C. for 2 hours, cooled at room temperature, and then weighed to calculate. Various evaluations were performed, and as shown in Table 1, similar results to Example 1 were obtained without any problem.

(Comparative Example 1) Polyacetal was not added.
The same method as in Example 1 except that the fine content was changed
Thus, PET having a fine content of 0.02 ppm was obtained.
As shown in Table 1, the molded plate obtained from the obtained PET was
The number of spherulites is 0.3 × 10 ⁹Pieces / m^TwoAnd again this PET
Fill the bottle with hot water at 90 ° C
After capping with a bottle machine, defeat the bottle and leave it,
Deformation of the plug of the bottle and leakage of the contents were examined.
Deformation of the stopper and leakage of the contents were observed. Bottle body
The part haze is 9.1%, which is bad.
The number was as low as 4000 times.

Comparative Example 2 Average Dispersion Diameter of Polyacetal
And P was changed in the same manner as in Example 1 except that the addition amount was changed.
I got ET. As shown in Table 1, the composition of the obtained PET
The number of spherulites in the plate is 40.0 × 10 ⁹Pieces / m^Two, Tc1
142.3 ° C, the haze of the formed plate was 25.9%. Ma
In addition, we conducted a leak evaluation test of the contents,
Deformation and leakage of contents were observed. To bottle body
Was 21.9% bad.

[0090]

[Table 1]

[0091]

According to the polyester of the present invention, it is possible to obtain a small-sized hollow molded article having good transparency and excellent heat-resistant dimensional stability, and has little mold contamination in bottle molding and the like, and is capable of continuous molding for a long time. It is possible to easily mold a large number of hollow molded articles with excellent transparency and excellent transparency.

[Brief description of the drawings]

FIG. 1 is a schematic view of an apparatus used for a method for producing a polyester of the present invention.

[Description of Signs] 1 Raw material chip supply port 2 Overflow discharge port 3 Discharge port of polyester chip and treated water 4 Drainer 5 Fine powder removing device 6 Piping 7 Treated water inlet 8 Adsorption tower 9 Ion exchange water introduced

Claims (9)

[Claims] 1. A polyester whose main repeating unit is ethylene terephthalate, wherein the number of spherulites generated when a molded body obtained by melt-molding the polyester is heated and crystallized is 2 × 10 ^9. Polyester for a hollow molded article, wherein the polyester is in a range of from about 20 × 10 ⁹ pieces / m ² and the haze of the molded article is 10% or less. 2. The polyester for a hollow molded article according to claim 1, wherein the crystallization temperature of the molded article obtained by melt-molding the polyester at the time of raising the temperature is in the range of 150 to 165 ° C. 3. The intrinsic viscosity of the polyester is 0.70 to 0.70.
3. The polyester according to claim 1, wherein the content of diethylene glycol copolymerized into the polyester is 0.90 dl / g, and the content of diethylene glycol is 1.0 to 5.0 mol% of the glycol component constituting the polyester. Or the polyester for hollow molded articles according to 3. 4. The polyester has a density of 1.37 g / cm.
^The polyester for a hollow molded article according to claim 1, wherein the number is ³ or more. 5. The polyester for a hollow molded article according to claim 1, wherein the acetaldehyde content is 10 ppm or less. 6. The polyester for a hollow molded article according to claim 1, wherein the content of the cyclic trimer is 0.5% by weight or less. 7. The method according to claim 1, wherein the amount of the cyclic trimer increased by melting at a temperature of 290 ° C. for 60 minutes is 0.30% by weight or less. Polyester for hollow moldings. 8. The hollow molded article according to claim 1, which is obtained using a Ge compound and / or a Ti compound as a polycondensation catalyst. For polyester. 9. A hollow molded article comprising the polyester according to claim 1, 2, 3, 4, 5, 6, 7, or 8.