JPH11152396A - Stretched hollow molded product of thermoplastic polyester resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a stretched hollow molded product of a thermoplastic polyester resin having high mechanical properties, gas barrier property, heat resistance and transparency. SOLUTION: The stretched hollow molded product is obtained from a polyester composition containing from 95 to 60 wt.% of a thermoplastic resin polyester (A) wherein the main repeating unit is ethylene terephthalate, and 5 to 40 wt.% of a thermoplastic polyester resin (B) wherein the main repeating unit is ethylene naphthalate. Here, the intrinsic viscosity of the hollow molded product is from 0.60 to 0.85 dl/g and the deformation rate of the body of the hollow molded product at 40 deg.C is 2.0% or smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stretched hollow stretched thermoplastic polyester resin article having excellent mechanical properties, gas barrier properties, heat resistance and transparency, which can be advantageously used as a container for food or beverages. Things.

[0002]

2. Description of the Related Art Polyethylene terephthalate resin is used for beverages such as carbonated beverages, juices and mineral water because of its excellent transparency, mechanical strength, heat resistance and gas barrier properties. It has been adopted as a material for containers and food containers. However, in recent years,
There has been a demand for a material having better properties than conventional polyethylene terephthalate resins in terms of heat resistance and gas barrier properties. In order to respond to such a demand, use of a polyethylene naphthalate resin having better heat resistance and gas barrier properties than a polyethylene terephthalate resin has been studied.

For example, JP-A-52-45466 describes that a hollow container is obtained from polyethylene naphthalate having excellent heat resistance and gas barrier properties. Japanese Patent Application Laid-Open No. 2-217222 discloses that a stretching index is 1
A polyethylene naphthalate bottle highly stretched to 30 cm or more and a method for producing the same are described. However, polyethylene naphthalate resin has poor moldability,
It is difficult to obtain a hollow molded body having excellent transparency and uniform thickness distribution.

Japanese Patent Application Laid-Open No. 64-85732 discloses 2,
Polyethylene naphthalate based on 65 to 98.5 mol% of 6-naphthalenedicarboxylic acid and 35 to 1.5 mol% of other dicarboxylic acids (terephthalic acid, isophthalic acid, etc.), and glycol component being mainly ethylene glycol Heat resistant bottles obtained from the copolymer are described. However, this copolymer has a third component of 10 mol%
Above this, the melt-polymerized resin does not show a melting point, and the crystallization speed becomes extremely slow, so that crystallization cannot be performed under practical conditions. For this reason, it is impossible to carry out a drying treatment or a solid-phase polymerization treatment for the purpose of increasing the molecular weight and decreasing the content of acetaldehyde which is a by-product during the production of the copolymer.

Japanese Patent Application Laid-Open No. Hei 2-274747 discloses a method in which a pre-kneaded product of polyethylene terephthalate resin and polyethylene naphthalate resin is mixed and used, and Japanese Patent Application Laid-Open No. 4-331255 discloses a method of melt-kneading both resins. By using things, heat resistance, transparency,
It is disclosed that a composition having excellent gas barrier properties is obtained, and a container or the like is produced therefrom. However,
When the pre-kneaded material is mixed and used for both resins, the resulting container has poor mechanical properties such as creep resistance, poor heat resistance and transparency, high acetaldehyde content, and low hollow molded product with low commercial value. I can't. Also, when both melt-kneaded products are used, only a hollow molded body having good transparency but having very high acetaldehyde content and very poor mechanical properties such as creep resistance and heat resistance can be obtained.

JP-A-3-87237 discloses a hollow molded article formed from a polyester resin composition containing a polyethylene terephthalate resin and a polyethylene naphthalate resin and highly stretched to a stretching index of 130 cm or more. In order to stretch to such a high stretching index, an unstretched preform having a very thick wall must be used. Temperature unevenness occurs between the part and the inside. Therefore, the stretching is not performed uniformly, and as a result, only a hollow molded article having poor transparency and poor mechanical properties can be obtained.

Thus, from a mixture of a polyethylene terephthalate resin and a polyethylene naphthalate resin,
At present, a polyester resin hollow body having satisfactory mechanical properties and transparency has not yet been obtained. That is, an object of the present invention is to provide a thermoplastic polyester resin stretched hollow molded article excellent in mechanical properties, heat resistance, gas barrier properties and transparency.

[0008]

As a result of intensive studies to achieve the above object, the mixing ratio of the two resins in the composition comprising the polyethylene terephthalate resin and the polyethylene naphthalate resin constituting the molded article, and The present inventors have found that the above object can be achieved by specifying the viscosity and the deformation ratio of the obtained molded article, and have reached the present invention. That is, the present invention is as follows.

(1) 95 parts of a thermoplastic polyester resin (A) whose main repeating unit is ethylene terephthalate
To 60% by weight and a thermoplastic polyester resin (B) whose main repeating unit is ethylene naphthalate
A stretched hollow molded article obtained from a polyester composition containing 40% by weight, wherein the intrinsic viscosity of the hollow molded article is 0.60
A stretched thermoplastic polyester resin molded article having a deformation rate of the body at 40 ° C. of 2.0% or less at 0.85 dl / g.

(2) The above (1) wherein the haze is 8% or less.
The stretched hollow molded article of the thermoplastic polyester resin according to the above.

(3) The above (1), wherein the total content of the cyclic trimer is 0.50% by weight or less, the haze is 5% or less, and the average density of the stretched portion is 1.360 g / cm ³ or more. The stretched hollow molded article of the thermoplastic polyester resin according to the above).

The stretched thermoplastic polyester resin molded article of the present invention having the above-mentioned constitution has excellent mechanical properties, heat resistance, gas barrier properties and transparency.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the hollow stretched thermoplastic polyester resin molded article of the present invention will be described in detail. In the present invention, the term "thermoplastic polyester resin in which the main repeating unit is ethylene terephthalate" (hereinafter referred to as "polyethylene terephthalate resin") (A) means that the ethylene terephthalate unit is at least 85 mol%, preferably at least 87 mol%, more preferably Is 90 mol%
A polyethylene terephthalate resin containing the above. When the ethylene terephthalate unit is less than 85 mol%, the resin is easily fused in a drying step or a solid phase polymerization step,
Moreover, the mechanical properties and heat resistance of the obtained hollow molded article are inferior.

The dicarboxylic acids used as copolymerization components other than terephthalic acid include, for example, aromatic acids such as isophthalic acid, diphenyl-4,4'-dicarboxylic acid, diphenoxyethanedicarboxylic acid, and 2,6-naphthalenedicarboxylic acid. Aliphatic dicarboxylic acids and their ester-forming derivatives, adipic acid, sebacic acid, azelaic acid, aliphatic dicarboxylic acids such as succinic acid and their ester-forming derivatives, cyclohexanedicarboxylic acid,
Examples include alicyclic dicarboxylic acids such as hexahydroterephthalic acid and ester-forming derivatives thereof, oxyacids such as p-oxybenzoic acid and oxycaproic acid, and ester-forming derivatives thereof.

In addition to ethylene glycol, examples of the glycol used as a copolymerization component include aliphatic glycols such as diethylene glycol, trimethylene glycol, tetramethylene glycol and neopentyl glycol, and alicyclic rings such as 1,4-cyclohexanedimethanol. Aromatic glycols such as aromatic glycols, bisphenol A, and alkylene oxide adducts of bisphenol A, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

Further, as the other copolymerization component in the polyethylene terephthalate resin (A), a trifunctional or higher polyfunctional compound can be used. For example, trimellitic acid, pyromellitic acid and the like can be mentioned as acid components, and glycerin and pentaerythritol can be mentioned as glycol components. The amount of the above-mentioned copolymer component to be used must be such that the polyethylene terephthalate resin (A) substantially maintains a linear shape.

As typical examples of the polyethylene terephthalate resin (A), (1) the main repeating unit is ethylene terephthalate, and (2) terephthalic acid as a dicarboxylic acid component is at least 85 mol%, preferably at least 87 mol%; More preferably 90 mol% or more, and (3) ethylene glycol as a glycol component is 85 mol% or more, preferably 87 mol% or more, more preferably 90 mol% or more.
Mol% or more, and diethylene glycol is 1.0 to
A linear polyester resin obtained from a composition containing 5.0 mol%, preferably 1.3 to 4.5 mol%, and more preferably 1.5 to 4.0 mol% is exemplified. When the diethylene glycol content is 1.0 mol% or more in the glycol component, the transparency of the obtained hollow molded article is good, and when it is 5.0 mol% or less, the creep resistance of the obtained hollow molded article is improved. It has good mechanical properties such as heat resistance and heat resistance, and has a low acetaldehyde content in the hollow molded article, and does not adversely affect the quality such as taste of the hollow molded article contents.

Polyethylene terephthalate resin (A)
Can be manufactured by a conventionally known manufacturing method. For example, a direct esterification method in which terephthalic acid and ethylene glycol and, if necessary, the third component is directly reacted to distill water and esterify, and then subjected to polycondensation under reduced pressure, dimethyl terephthalate and ethylene glycol Further, if necessary, a transesterification method in which the third component is reacted to distill off methyl alcohol to carry out transesterification, and then to carry out polycondensation under reduced pressure, may be mentioned. Further, solid-state polymerization may be performed in order to increase the intrinsic viscosity of the obtained polyester resin and reduce the acetaldehyde content.

As a transesterification catalyst in the transesterification method, a carboxylic acid metal salt compound of a carboxylic acid and a metal such as Mg, Mn, Ca, Zn is used.
e compounds, Sb compounds, Ti compounds and the like are used.
Further, in order to eliminate the activity of the transesterification catalyst, a phosphorus compound such as phosphoric acid or trimethyl phosphate can be added after the transesterification reaction is completed. In the case of the direct esterification method, a Ge compound, an Sb compound, a Ti compound or the like is used as a polycondensation catalyst. In order to control the diethylene glycol content, a basic compound such as a tertiary amine such as triethylamine and tri-n-butylamine, and a quaternary ammonium salt such as tetraethylammonium hydroxide may be added in the esterification step.

The intrinsic viscosity of the polyethylene terephthalate resin (A) is 0.65 to 0.90 dl / g, preferably 0.67 to 0.87 dl / g, more preferably 0.7
It is in the range of 0 to 0.85 dl / g. 0.65 dl / g
If it is above, the mechanical properties of the obtained hollow molded article are good, while if it is 0.90 dl / g or less, the resin temperature at the time of melting in the molding machine is appropriate, and there is almost no thermal decomposition of the resin. There is no problem such as the molded article being colored yellow.

The bulk density of the polyethylene terephthalate resin (A) chips is preferably 0.83 to 0.97 g /
cm ³ , more preferably 0.84 to 0.96 g / c
m ³ , more preferably 0.85 to 0.95 g / cm ³
It is. For example, when the chip size is very large or when a large amount of fine chips or powder is mixed, the bulk density becomes small. Bulk density is 0.83 g / cm ³
If it is above, the fluidity of the chip in the injection molding machine is good, it can be melted in a uniform state, and can be uniformly melt-mixed with the polyethylene naphthalate resin (B). As a result, the transparency of the hollow molded article becomes very good, and uniform stretching can be easily performed. Therefore, the thickness of the body or the like of the obtained hollow molded body is uniform, and as a result, the deformation rate of the body is reduced. In addition, the resin obtained by solid-state polymerization has a large chip size, or a large amount of fine chips and powders mixed therein, and when the bulk density is small, the density difference between chips becomes extremely large, The molecular weight distribution of the polyethylene terephthalate resin (A) becomes very wide. Then, polyethylene terephthalate resin (A) in the injection molding machine
Becomes even more uneven, and uniform mixing with the polyethylene naphthalate resin (B) becomes very difficult.
As a result, the transparency of the hollow molded body is further deteriorated, and since uniform stretching is impossible, uneven thickness is generated on the body of the hollow molded body, and the deformation rate of the body is increased. Further, when the bulk density is 0.97 g / cm ³ or less, the filling in the injection molding machine is normal and uniformly melts, so that the heat generation in the molding machine is suppressed, and therefore the acetaldehyde content of the hollow molded body is reduced, The flavor of the contents does not matter.

The "thermoplastic polyester resin whose main repeating unit is composed of ethylene naphthalate" (hereinafter referred to as "polyethylene naphthalate resin") (B) means that the ethylene naphthalate unit is 85 mol% or more, preferably 87 mol% or more.
It is a polyethylene naphthalate resin containing at least 90 mol%, more preferably at least 90 mol%. When the ethylene naphthalate unit is less than 85 mol%, the resin is easily fused in a drying step or a solid-phase polymerization step of the resin, and the mechanical properties, gas barrier properties and heat resistance of the obtained hollow molded article are reduced. become worse.

Examples of the dicarboxylic acid other than naphthalenedicarboxylic acid used as a copolymerization component include terephthalic acid, isophthalic acid, diphenyl-4,4'-
Dicarboxylic acid, diphenoxyethane dicarboxylic acid, 2,
Aromatic dicarboxylic acids such as 7-naphthalenedicarboxylic acid and their ester-forming derivatives, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid and succinic acid and their ester-forming derivatives, cyclohexanedicarboxylic acid, hexahydro Examples thereof include alicyclic dicarboxylic acids such as terephthalic acid and their ester-forming derivatives, oxyacids such as p-oxybenzoic acid and oxycaproic acid, and their ester-forming derivatives.

Examples of the glycol other than ethylene glycol used as a copolymerization component include aliphatic glycols such as diethylene glycol, trimethylene glycol, tetramethylene glycol and neopentyl glycol, and alicyclic rings such as 1,4-cyclohexanedimethanol. Aromatic glycols such as aromatic glycols, bisphenol A, and alkylene oxide adducts of bisphenol A, polyethylene glycol, polypropylene glycol, and polytetramethylene glycol.

Further, as the other copolymerization component in the polyethylene naphthalate resin (B), a trifunctional or higher polyfunctional compound can be used. For example, trimellitic acid, pyromellitic acid and the like can be mentioned as acid components, and glycerin and pentaerythritol can be mentioned as glycol components. The amount of the above-mentioned copolymer component to be used must be such that the polyethylene naphthalate resin (B) substantially maintains a linear shape.

As typical examples of the polyethylene naphthalate resin (B), (1) the main repeating unit is ethylene-
2,6-naphthalenedicarboxylate,
(2) 85 mol% or more of 2,6-naphthalenedicarboxylic acid as a dicarboxylic acid component, preferably 87 mol% or more, more preferably 90 mol% or more, and (3) ethylene glycol as a glycol component, 85 mol% or more, preferably Is at least 87 mol%, more preferably 90 mol%
As described above, a linear polyester resin obtained from a composition containing 1.0 to 5.0 mol%, preferably 1.3 to 4.5 mol%, more preferably 1.5 to 4.0 mol% of diethylene glycol is No. When the diethylene glycol content is 1.0 mol% or less, the transparency of the obtained hollow molded article is extremely poor, and when it is 5.0 mol% or more, the obtained hollow molded article has mechanical properties such as creep resistance. The properties and heat resistance of the hollow molded article are deteriorated, and the acetaldehyde content of the hollow molded article is greatly increased, thereby adversely affecting the quality of the hollow molded article, such as taste.

The above-mentioned polyethylene naphthalate resin (B) can be produced by a conventionally known production method. For example, a direct esterification method in which 2,6-naphthalenedicarboxylic acid and ethylene glycol and, if necessary, the third component is directly reacted, water is distilled off, esterified, and then polycondensed under reduced pressure, Dimethyl-2,6-
It is produced by a transesterification method or the like in which naphthalenedicarboxylate and ethylene glycol and, if necessary, the third component are reacted to distill off methyl alcohol and transesterify, followed by polycondensation under reduced pressure. Also,
Solid phase polymerization may be performed to increase the intrinsic viscosity of the resulting polyester resin and reduce the acetaldehyde content.

As the catalyst used in producing the polyethylene naphthalate resin (B), the same catalyst as that used in producing the polyethylene terephthalate resin (A) can be used.

The intrinsic viscosity of the polyethylene naphthalate resin (B) is preferably 0.50 to 0.90 dl / g, more preferably 0.53 to 0.85 dl / g, and still more preferably 0.55 to 0.85 dl / g. It is in the range of 80 dl / g.
If it is at least 0.50 dl / g, the mechanical properties of the obtained hollow molded article will be good. On the other hand, if it is 0.90 dl / g or less, the resin temperature at the time of melting in a molding machine is appropriate, there is almost no thermal decomposition, and there is no problem such that the obtained hollow molded article is colored yellow.

The bulk density of the polyethylene naphthalate resin (B) chips used in the present invention is preferably 0.8
^{3 to} 0.97 g / cm ³ , more preferably 0.84 to
0.96 g / cm ³ , more preferably 0.85 to 0.5 g / cm ³ .
It is 95 g / cm ³ . For example, when the chip size is very large or when fine chips or powders are mixed in a large amount, the bulk density becomes small. When the bulk density is 0.83 g / cm ³ or more, the chips have good fluidity in the injection molding machine, can be melted in a uniform state, and can be uniformly melt-mixed with the polyethylene terephthalate resin (A). As a result, the transparency of the hollow molded article becomes very good, and uniform stretching can be easily performed. Therefore, the thickness of the body or the like of the obtained hollow molded body is uniform, and as a result, the deformation rate of the body is reduced. In addition, the resin obtained by solid-state polymerization has a large chip size, or a large amount of fine chips and powders mixed therein, and when the bulk density is small, the density difference between chips becomes extremely large, The molecular weight distribution of the polyethylene naphthalate resin (B) becomes very wide. Then, the molten state of the polyethylene naphthalate resin (B) in the injection molding machine becomes more uneven, and the polyethylene terephthalate resin (A)
And it becomes very difficult to mix uniformly. As a result, the transparency of the hollow molded article is further deteriorated, or uneven thickness is generated on the body of the hollow molded article because uniform stretching is impossible,
The deformation rate of the torso increases. In addition, when the bulk density is 0.97 g / cm ³ or less, the filling in the injection molding machine is normal and uniformly melts, thereby suppressing heat generation in the molding machine. Therefore, the acetaldehyde content of the hollow molded body becomes 50 ppm or less. The flavor of the contents does not matter.

In order to obtain a hollow molded article having excellent transparency, the ratio of the bulk density of the polyethylene terephthalate resin (A) to the bulk density of the polyethylene naphthalate resin (B) must be 0.8 to 1.2. It is desirable that More preferably from 0.85 to 1.15, even more preferably from 0.9 to 1.
1.1. When the ratio of the bulk densities of the two is 0.8 to 1.2, the mixing ratio does not fluctuate when the mixed resins are sent to a hopper or the like of a molding machine. Does not change to cause a change in the deformation rate of the body of the hollow molded article.

The stretched hollow molded article made of a thermoplastic polyester resin of the present invention comprises a polyethylene terephthalate resin (A).
A polyester composition containing 95 to 60% by weight and 5 to 40% by weight of a polyethylene naphthalate resin (B), preferably a polyethylene terephthalate resin (A) 93
~ 65% by weight and polyethylene naphthalate resin (B) 7
And more preferably a polyethylene terephthalate resin (A) 92 to
70% by weight and polyethylene naphthalate resin (B) 8 to
30% by weight of the polyester composition. When the polyethylene terephthalate resin (A) exceeds 95% by weight, the ultraviolet ray blocking properties and gas barrier properties are deteriorated. When the polyethylene terephthalate resin (A) is less than 60% by weight, mechanical properties such as creep resistance are deteriorated.

The intrinsic viscosity of the hollow molded article of the present invention is 0.6
0 to 0.85 dl / g, preferably 0.63 to 0.83
dl / g. If it is less than 0.60 dl / g, the mechanical strength and impact resistance of the hollow molded article are insufficient.
When it exceeds 85 dl / g, there are problems such as an increase in acetaldehyde content.

The deformation rate of the body of the hollow molded article of the present invention measured at 40 ° C. is 2.0% or less, preferably 1.5%.
It is important that: When the hollow molded article of the present invention is used as a container for a carbonated beverage, the deformation rate of the trunk is 2.
If it exceeds 0%, expansion occurs mainly in the circumferential direction of the hollow molded body during standing due to the internal pressure of carbon dioxide gas, and as a result, phenomena such as lowering of the liquid level occur and the commercial value is lost. In addition, when used as a juice beverage container containing carbon dioxide such as a juice carbonated beverage, the beverage is filled and sealed with a cap, and then heated or sterilized by showering with hot or hot water,
If the deformation rate of the body exceeds 2.0%, the hollow molded body expands in the circumferential direction during heat sterilization, and the same phenomenon as described above occurs.

The stretched hollow molded article of the thermoplastic polyester resin of the present invention comprises an unstretched plug serving as a spout when the hollow molded article is filled with the contents, and substantially the bottom of the hollow molded article. It is composed of an unstretched bottom portion and a stretched body portion present between them.

The "deformation rate of the body of the hollow molded article" described in the present specification means that about 4.0 G. of carbon dioxide gas is applied to the hollow molded article. V. It corresponds to the deformation rate of the body due to the stress acting in the circumferential direction when the container is filled and left at 40 ° C. The stress acting in the circumferential direction due to the internal pressure is obtained by the following equation, and this stress is applied to a sample cut from the body of the hollow molded body to determine the deformation rate of the body of the hollow molded body. Circumferential stress (kg / cm ² ) = (P × r) / t [where P is the internal pressure (kg / cm ² ) of the hollow molded body, r
Is the radius (c) of the part where the cross-sectional area of the body of the hollow molded body is almost the same
m) and t represents the thickness (cm) of the hollow molded body.]
In order to measure the deformation rate of the body of the hollow molded body, three positions in the height direction were selected at portions where the cross-sectional area of the body of the hollow molded body was substantially the same, and the length in the circumferential direction was 50 from each of the positions. ~
A sample having a width of 80 mm and a width of 5 mm is cut out and provided for measurement.

The method for reducing the deformation rate of the hollow molded article of the present invention to 2.0% or less is as follows: (1) The blending ratio of the polyethylene naphthalate resin (B) in the hollow molded article is 5 to 40% by weight, preferably (2) The polyethylene terephthalate resin (A) and the polyethylene naphthalate resin (B) each have a bulk density of 0.83 to 30% by weight.
A method of using a polyester composition having a resin density of 0.97 g / cm ³ and a bulk density ratio of both resin chips of 0.8 to 1.2; (3) a stretching temperature of about 90 to 1
30 ° C., the stretching ratio in the circumferential direction is about 4.0 times or more, the stretching ratio in the longitudinal direction is about 2.2 times or more, and the stretching index is 1
A method of stretching the film so as to keep it at 30 cm or less, (4) a method of appropriately combining them, and the like can be cited. The stretching index is defined as shown below.

[0038]

(Equation 1)

In the above formula,

[0040]

(Equation 2)

Although the hollow molded article of the present invention has better heat resistance than the hollow molded article made of polyethylene terephthalate resin alone, for applications requiring even higher heat resistance, heat treatment is performed in a mold heated after stretching blow. It is better to do. The average density of the stretched portion of the heat-treated hollow molded article is usually 1.360 g / cm ³ or more. The average density of the stretched portion of the hollow molded body is preferably 1.363 g / cm ³ or more, more preferably 1.365 g / cm ³ or more. When the average density is 1.360 g / cm ³ or more, the heat resistance of the obtained hollow molded article is good.

The total content of the cyclic trimers in the polyester resins (A) and (B) constituting the hollow molded article of the present invention is preferably 0.50% by weight or less, more preferably 0.45% by weight or less. , More preferably 0.40% by weight
It is as follows. When heat treatment is performed in a heating mold at the time of molding in order to impart heat resistance to the hollow molded body, when the total content of the cyclic trimers exceeds 0.50% by weight, the amount of the oligomer attached to the mold surface sharply increases. And the transparency of the obtained hollow molded article becomes extremely poor. The term "cyclic trimer" used herein refers to both a cyclic trimer composed of ethylene terephthalate units and a cyclic trimer composed of ethylene naphthalate units, and the contents of both are summed. The amount obtained is the “total content”.

The total content of the cyclic trimers contained in the polyester resins (A) and (B) is preferably 0.40% by weight of the polyethylene terephthalate resin (A).
Or less, more preferably 0.38% by weight or less, still more preferably 0.35% by weight or less. Further, the total content of the cyclic trimer of the polyethylene naphthalate resin (B) is 0.1%.
It is at most 50% by weight, preferably at most 0.45% by weight, more preferably at most 0.40% by weight.

The haze of the hollow molded article of the present invention is preferably 8% or less, more preferably 5% or less, and further preferably 3% or less. When the haze exceeds 8%, the hollow molded article exhibits a cloudy pearly luster, and loses commercial value.

The content of acetaldehyde contained in the hollow molded article of the present invention is preferably 50 ppm or less, more preferably 30 ppm or less, and further preferably 20 ppm or less. When the acetaldehyde content exceeds 50 ppm,
Acetaldehyde odor is transferred to the contents of the hollow molded article, which is particularly problematic in the case of beverages.

The polyester composition for forming the hollow molded article of the present invention includes a heat stabilizer, a thermooxidative stabilizer, an antistatic agent,
A weathering stabilizer, a lubricant, a pigment, a dye / pigment dispersant, a defective molded article of the present invention, and the like can be added as long as the object of the present invention is not impaired.

As a method for uniformly mixing the polyethylene terephthalate resin (A) and the polyethylene naphthalate resin (B) of the present invention, various known methods can be used. For example, a method using a double cone blender, a ribbon blender, or the like can be applied. Alternatively, both resins mixed by such a method can be melt-kneaded by a single-screw extruder, a twin-screw extruder, a vented extruder, or the like, and granulated.

The hollow molded article of the present invention can be obtained by a two-step method (cold parison method) in which a bottomed preform (parison) molded by a known injection molding machine or the like is stretch-blown by a stretch blow molding machine, or It can be manufactured by a stretch blow molding method of a one-stage method (hot parison method) in which the forming of the preform and the stretch blow molding are performed by the same machine. In order to reduce the acetaldehyde content of the hollow molded body, it is preferable to use a vent type injection molding machine.

The hollow molded article of the present invention preferably has a total content of the cyclic trimer of 0.50% by weight or less, a haze of 5% or less, and an average density of the stretched portion of 1.360 g / cm ³ or more. Are particularly preferred.

[0050]

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) of polyethylene terephthalate (hereinafter referred to as “PET”) resin (A) and stretched hollow molded article The viscosity of the molded article is determined by cutting a sample from the hollow molded article and using it as a measurement sample. 1,1,2,2-tetrachloroethane /
It was determined from the solution viscosity at 30 ° C. in a phenol (2: 3 weight ratio) mixed solvent.

(2) Intrinsic viscosity (IV) of polyethylene naphthalate (hereinafter referred to as "PEN") resin (B) 1,1,2,2-tetrachloroethane / p-chlorophenol (1: 3 weight ratio) mixture It was determined from the solution viscosity at 30 ° C. in a solvent.

(3) Diethylene glycol (hereinafter referred to as "DE
G)) Content The resin was decomposed with methanol, and the amount of DEG was quantified by gas chromatography and expressed as a ratio (mol%) to the total glycol component.

(4) Acetaldehyde (hereinafter referred to as "AA") content A resin pellet or a sample having a size of 2 to 3 mm square from the mouth of a container, and 2 ml of distilled water per 1 g of the sample are placed in a glass ampoule substituted with nitrogen. And seal the upper part at 160 ° C for 2
A time-extraction treatment was performed, and after cooling, AA in the extract was measured by high-sensitivity gas chromatography, and the concentration was indicated in ppm.

(5) Total content of cyclic trimer (hereinafter referred to as “PET-CT”) in PET resin 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 the cyclic trimer composed of ethylene terephthalate units and the cyclic trimer composed of ethylene naphthalate units were quantified by liquid chromatography.

(6) Total content of cyclic trimer (hereinafter referred to as “PEN-CT”) in PEN resin The same method as that for PET resin is used.

(7) Total content of cyclic trimer (hereinafter referred to as "CT") in the hollow molded article The same method as that for PET resin.

(8) Bulk density (hereinafter referred to as “BD”) Measured by a method according to JIS K6721.

(9) Haze (% haze) A sample was cut from the body (thickness: about 0.4 mm) of the hollow molded article, and measured with a haze meter manufactured by Toyo Seiki Seisaku-sho.

(10) Deformation Rate Measurement Test of Body of Hollow Molded Body 1) Sample for Deformation Rate Measurement In the portion where the cross-sectional area of the stretched body of the hollow molded body shows the maximum value or in the portion where the cross-sectional area is the same Select three positions in the height direction, and the circumferential length from each point = 50 to 80 m
A sample having a width of 5 mm and a width of 5 mm is cut out, and is dried and then subjected to measurement. 2) Deformation rate measurement The sample is loaded with the stress determined by the following formula, and the rate of change of the length of the sample after being left at 40 ° C. for 40 minutes is determined as an average value of n = 3. The stress applied to the sample is determined by the following equation. Stress (kg / cm ² ) = (P × r) / t [where P is about 4.0 G. V. Filled with carbon dioxide gas,
Internal pressure of the hollow molded body at 40 ° C., that is, 6.7 kg
/ Cm ² , r indicates the radius (cm) of the portion where the cross-sectional area of the body of the hollow molded body is substantially the same, and t indicates the thickness (cm).]

(11) Density of Hollow Molded Body A sample for measurement was sampled from the same site as the sample for measurement of deformation rate, and measured at 25 ° C. using a density gradient tube of a mixed solvent of carbon tetrachloride / n-heptane.

(12) Volume change test 3.8 to 3.5 parts were prepared by mixing sodium bicarbonate and dilute sulfuric acid in a hollow molded article.
4.0G. V. And sealed at about 40 ° C after sealing.
It is left for a few days, and the change rate of the internal volume of the hollow molded body before and after the test is determined.

(13) Heat resistance The hollow molded body is filled with hot water at 90 ° C., capped, and left for 5 minutes. Thereafter, after cooling with water at 10 ° C., the water was drawn in, and the shrinkage was determined from the change in the mesh size.

Examples 1 to 4 1) PET resin PET resin no. No. 2 was prepared by subjecting a terephthalic acid and ethylene glycol to a direct esterification reaction, followed by solid-state polymerization of a melt-polymerized polymer chip which was polycondensed in the presence of a germanium dioxide catalyst. In addition, PET resin No.
No. 3 was produced by transesterification and melt polymerization of dimethyl terephthalate, dimethyl-2,6-naphthalenedicarboxylate and ethylene glycol by a conventional method, followed by solid phase polymerization. In addition, PET resin No. Reference numeral 1 denotes RT553C manufactured by Nihon Unipet Co., Ltd. Table 1 shows the characteristics of the resin. In Table 1, ET indicates an ethylene terephthalate unit, and EN indicates an ethylene-2,6-naphthalate unit.

2) PEN resin PEN resin No. No. 4 was prepared from dimethyl-2,6-naphthalenedicarboxylate and ethylene glycol by a conventional method. In addition, PEN resin No. 5 was produced from dimethyl-2,6-naphthalenedicarboxylate, dimethyl terephthalate and ethylene glycol by a conventional method. All are resins obtained by solid phase polymerization. Table 1 shows the characteristics of the resin.

[0066]

[Table 1]

3) Molding of Hollow Molded Article Using the above PET resin and PEN resin, a preliminary molded article was molded by an M-100 injection molding machine manufactured by Meiki Seisakusho. The injection molding temperature was 295 ° C. Next, this preform is
Using an POP-01 LB-01E molding machine, biaxially stretch-blow (approx. 20 ° C mold) about 2.5 times in the longitudinal direction and about 5 times in the circumferential direction to make a container with a capacity of 1500 ml. did. The stretching temperature is about 100 to 1 depending on the blend ratio.
The temperature was appropriately changed between 20 ° C. Table 2 shows the polyester composition and the physical properties of the obtained container together with Comparative Examples. As is clear from Table 2, the hollow molded container of the present invention exhibited excellent transparency and creep resistance, had a low AA content, and also had excellent volume change test results under carbon dioxide gas pressure.

Comparative Example 1 A container having a capacity of 1500 ml was molded and evaluated in the same manner as in Example 1 except that the stretching ratio in the circumferential direction was about 3.8 times. As shown in Table 2, since the deformation rate was large, the result of the volume change test was poor.

Comparative Example 2 PET resin no. 3 and PEN resin no. 5, and a container having a capacity of 1500 ml was formed in the same manner as in Example 1 except that the blending ratio (weight ratio) was changed to 50/50. Table 2 shows the results. Due to the large deformation rate, the result of the volume change test was poor.

[0070]

[Table 2]

Example 5 PET resin no. 2 and PEN resin No. 5, and a 1500 ml container was molded under the same conditions as in Example 1 except that the temperature of the blow mold was set to about 140 ° C. Table 3 shows the polyester composition and the results. A container having excellent transparency, little deformation rate and small volume change, and good heat resistance was obtained.

Comparative Example 3 PET resin no. 1 and PEN resin No. 4, and a 1500 ml container was molded under the same conditions as in Comparative Example 1 except that the temperature of the blow mold was set to about 140 ° C. Table 3 shows the polyester composition and the results.

[0073]

[Table 3]

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The stretched hollow molded article of the thermoplastic polyester resin of the present invention has excellent heat resistance, transparency, gas barrier properties and mechanical properties. Therefore, it can be used very preferably as a material for beverage containers and food containers such as carbonated beverages, juices and mineral water.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yoshitaka Eto 248-20 Takashiro, Shiga-cho, Shiga-gun, Shiga

Claims (3)

[Claims] 1. A thermoplastic polyester resin (A) having a main repeating unit of ethylene terephthalate in a proportion of 95-6.
0% by weight, and 5 to 40 parts of a thermoplastic polyester resin (B) whose main repeating unit is ethylene naphthalate.
A stretched hollow molded article obtained from a polyester composition containing at least 1% by weight, wherein the hollow molded article has an intrinsic viscosity of 0.60 to 0.60%.
A stretched thermoplastic polyester resin hollow molded article having a deformation rate of 0.85 dl / g and a trunk portion at 40 ° C. of 2.0% or less at 40 ° C. 2. The stretched thermoplastic polyester resin hollow molded article according to claim 1, wherein the haze is 8% or less. 3. The total content of the cyclic trimer is 0.50% by weight.
2. The stretched thermoplastic polyester resin hollow molded article according to claim 1, wherein the haze is 5% or less, and the average density of the stretched portion is 1.360 g / cm ³ or more.