JPH09124785A - Polyester resin composition and production thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyester resin composition excellent in transparency and also in heat resistance and UV screening ability by using a polyester composition consisting of specified structural units. SOLUTION: This composition consists of structural units (a) represented by formula I, structural units (b) represented by formula II and structural units (c) represented by formula III, wherein the amount of the units (c) is 30-200mol when the smaller amount between those of the units (a) and (b) is 100mol. The desirable composition is one obtained by melting and kneading a polyethylene terephthalate forming the structural units (a) and a polyethylene naphthalate forming the structural units (b) in such a manner that the amount of the structural units (c) is 30-200mol when the smaller amount between those of the units (a) and (b) is 100mol.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polyester resin composition and a method for producing the same, and more specifically, a polyester capable of obtaining a molded product such as a stretched bottle which is excellent in transparency, heat resistance and UV blocking property. The present invention relates to a resin composition and a method for producing the same.

[0002]

BACKGROUND OF THE INVENTION Conventionally, glass containers have been widely used as containers for filling seasonings, oils, juices, carbonated drinks, beer, sake, cosmetics, detergents and the like.

However, since the glass container is high in manufacturing cost, it is usually recycled by recycling an empty container after use and refilling the contents. When the glass container is recycled as described above, the glass container is heavy and the transportation cost is high, and the glass container is easily damaged.

In an attempt to eliminate these drawbacks of glass containers, the conversion from glass containers to various plastic containers has been rapidly progressing recently. As the material, various plastics are adopted depending on the type of the filled contents and the purpose of use, and among these plastic materials, saturated crystalline polyester resin such as polyethylene terephthalate has mechanical strength, heat resistance, Since it is excellent in transparency and gas barrier property, the bottle obtained from it is widely used as a material for containers of juice, soft drinks, carbonated drinks, seasonings, detergents, cosmetics and the like.

In order to manufacture a bottle from such a saturated crystalline polyester, a saturated polyester is generally injection-molded to form a preform, which is then inserted into a mold having a predetermined shape and stretch blown. Molded to obtain a bottle having a spout and a body.

Among the bottles thus obtained, the bottles used for beverages such as juices are required to have heat resistance capable of withstanding heat sterilization of the contents, so that after the blow molding, it is usually necessary to further Heat resistance is improved by heat treating the bottle.

However, when heat sterilizing a bottle manufactured using polyethylene terephthalate, the heat resistant temperature of the bottle currently used is limited to about 90 ° C. in consideration of productivity.

Further, in order to improve heat resistance, a method of improving heat resistance by blending polyethylene terephthalate with a resin having a higher glass transition point was also studied. For example, paying attention to the high glass transition temperature of polyethylene naphthalate, blending with polyethylene terephthalate has been attempted. However, polyethylene naphthalate and polyethylene terephthalate are inferior in compatibility, and if they are simply blended, the resulting blend becomes white and opaque, and the resulting molded article has a problem in that transparency is significantly inferior. It was

Therefore, a polyester resin composition having high transparency and excellent heat resistance from polyethylene terephthalate and polyethylene naphthalate,
And the appearance of the manufacturing method was desired.

[0010]

SUMMARY OF THE INVENTION The present invention is intended to solve the problems associated with the prior art as described above, and is a polyester resin composition capable of forming a stretched bottle excellent in transparency, heat resistance and UV blocking property. It is intended to provide a product and a manufacturing method thereof. Furthermore, it is an object of the present invention to provide a preform and a polyester bottle obtained from this polyester resin composition.

[0011]

The polyester resin composition according to the present invention comprises a structural unit (a) represented by the following general formula (1):

[0012]

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A structural unit (b) represented by the following general formula (2):

[0014]

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And a structural unit (c) represented by the following general formula (3):

[0016]

[Chemical 6]

When the amount of the constitutional unit (c) represented by the general formula (3) is 100 moles of the constitutional unit (a) or (b), whichever is smaller, In contrast, it is characterized by being present in an amount of 30 to 200 mol.

In a preferred embodiment of the method for producing a polyester resin composition according to the present invention, polyethylene terephthalate having the structural unit (a) represented by the general formula (1) and the structural unit (2) represented by the general formula (2) b) the polyethylene naphthalate and the polyester having the structural unit (c) represented by the general formula (3), the amount of the structural unit (c) represented by the general formula (3) is ) Or (b), whichever is smaller, is 100-mol, and the mixture is melt-kneaded so as to be 30 to 200 mol with respect to this amount. As yet another manufacturing method,
A polyethylene terephthalate having the structural unit (a) represented by the general formula (1) and a polyethylene naphthalate having the structural unit (b) represented by the general formula (2) are prepared.
The constituent unit (c) represented by the general formula (3) is melt-kneaded at 0 ° C to 330 ° C for 30 seconds to 600 seconds to cause a transesterification reaction of polyethylene terephthalate and polyethylene naphthalate as described above. May be produced in any amount, and polyethylene terephthalate having the structural unit (a) represented by the general formula (1) and polyethylene naphthalate having the structural unit (b) represented by the general formula (2) may be produced. , In the molding machine after dry blending 26
The structural unit (c) represented by the general formula (3) is melt-kneaded at 0 ° C. to 330 ° C. for 30 seconds to 600 seconds, and a transesterification reaction of polyethylene terephthalate and polyethylene naphthalate is performed to obtain the above-described amount of the structural unit (c). May be generated by.

The polyester preform and polyester bottle of the present invention can be obtained from the polyester resin composition as described above.

[0020]

DETAILED DESCRIPTION OF THE INVENTION The polyester resin composition according to the present invention, the method for producing the polyester resin composition, the polyester preform obtained from the polyester resin composition and the polyester bottle will be specifically described below.

Polyester Resin Composition The polyester resin composition according to the present invention comprises a structural unit (a) represented by the following general formula (1):

[0022]

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A structural unit (b) represented by the following general formula (2),

[0024]

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And a structural unit (c) represented by the following general formula (3):

[0026]

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When the amount of the constitutional unit (c) represented by the general formula (3) is 100 moles of the constitutional unit (a) or (b), whichever is smaller, On the other hand, it is contained in an amount of 30 to 200 mol.

The structural unit (a) represented by the general formula (1) in the polyester resin composition of the present invention is derived from terephthalic acid or its ester-forming derivative, and ethylene glycol or its ester-forming derivative. .

The structural unit (b) represented by the general formula (2) in the polyester resin composition according to the present invention is 2,6-naphthalenedicarboxylic acid or its ester-forming derivative, and ethylene glycol or its ester-forming derivative. Derived from a sex derivative.

The structural unit (c) represented by the general formula (3) in the polyester resin composition according to the present invention includes terephthalic acid or its ester-forming derivative and 2,6-naphthalenedicarboxylic acid or its derivative. An ester-forming derivative,
Derived from ethylene glycol or its ester-forming derivatives.

The polyester resin composition according to the present invention is
It may contain a structural unit derived from terephthalic acid, a dicarboxylic acid other than 2,6-naphthalenedicarboxylic acid, and a dihydroxy compound other than ethylene glycol. Examples of dicarboxylic acids other than terephthalic acid and 2,6-naphthalenedicarboxylic acid include phthalic acid, isophthalic acid,
Aromatic dicarboxylic acids such as 2,7-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, diphenyldicarboxylic acid and diphenoxyethanedicarboxylic acid, and aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid and decanedicarboxylic acid And alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid.

Dihydroxy compounds other than ethylene glycol include trimethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, hexamethylene glycol, dodecamethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, and other aliphatic glycols. Alicyclic glycols such as cyclohexanedimethanol, bisphenols, hydroquinone, 2,2-bis (4-
Examples include aromatic diols such as β-hydroxyethoxyphenol) propane. This terephthalic acid, 2,6-
The constituent unit derived from a dicarboxylic acid other than naphthalenedicarboxylic acid and a dihydroxy compound other than ethylene glycol may be contained in an amount of 20 mol% or less.

The polyester resin composition used in the present invention is a polyfunctional compound such as trimesic acid, pyromellitic acid, trimethylolethane, trimethylolpropane, trimethylolmethane, pentaerythritol, or a polyfunctional compound thereof. It may contain a small amount of the structural unit derived from, for example, 3 mol% or less.

The resin composition according to the present invention has the general formula (3):
When the amount of the structural unit (c) represented by the formula (a) or (b), whichever is smaller, is 100 mol, the amount of the structural unit (c) is 30 to 200 mol, and preferably 30 to 200 mol. 40-150 mol, particularly preferably 50-100
Present in molar amounts. When this amount is less than 30 mol, the resulting polyester resin composition becomes white and opaque, and when it is 200 mol or more, the moldability or heat resistance becomes poor.

Further, the polyester resin composition according to the present invention contains a crosslinking agent, a heat resistance stabilizer, a weather resistance stabilizer, an antistatic agent, a lubricant, a release agent, an inorganic filler, a pigment dispersant, a pigment or a dye. Various compounding agents may be blended.

The polyester resin composition of the present invention having such a composition is excellent in transparency, heat resistance and ultraviolet ray blocking property, and is used as it is or in the form of sheet, plate, tube, hollow, container. Can be used in various shapes such as.

Method for Producing Polyester Resin Composition The polyester resin composition according to the present invention can be obtained by the following method.

The polyester resin composition according to the present invention is
For example, it can be obtained by melt-kneading polyethylene terephthalate having the structural unit (a) represented by the general formula (1) and polyethylene naphthalate having the structural unit (b) represented by the general formula (2).

The polyethylene terephthalate having the structural unit (a) represented by the general formula (1) used here is obtained by using terephthalic acid or its ester-forming derivative and ethylene glycol or its ester derivative as raw materials. This polyethylene terephthalate preferably has at least 80 mol% or more of the structural unit (a) represented by the general formula (1) in all structural units, but the constitutional units other than the structural unit represented by the general formula (1) are included. The unit may be included in an amount of less than 20 mol%.

Specific examples of the dicarboxylic acid used in the constitutional unit other than the constitutional unit represented by the general formula (1) include phthalic acid, isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid and diphenoxyethanedicarboxylic acid. And aromatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid, and decanedicarboxylic acid; and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid.

Examples of the dihydroxy compound used in the constitutional unit other than the constitutional unit represented by the general formula (1) include trimethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, hexamethylene glycol, dodecamethylene glycol, diethylene glycol. , Aliphatic glycols such as triethylene glycol and tetraethylene glycol, alicyclic glycols such as cyclohexanedimethanol, bisphenols, hydroquinone and aromatic diols such as 2,2-bis (4-β-hydroxyethoxyphenol) propane And the like.

The above-mentioned polyethylene terephthalate can be manufactured by a conventionally known manufacturing method. The polyethylene terephthalate thus obtained is substantially linear, which is confirmed by the fact that the polyethylene terephthalate obtained is dissolved in o-chlorophenol.

Such polyethylene terephthalate has an intrinsic viscosity [η] measured in o-chlorophenol at 25 ° C. of usually 0.6 to 1.4 dl / g, preferably
0.6-1.0 dl / g, more preferably 0.7-
It is in the range of 0.95 dl / g. [Η] is 0.6 dl /
When it is less than g, the heat resistance, transparency and mechanical strength of the obtained preform and bottle become poor, while when it is more than 1.4 dl / g, the preform moldability and stretch blow molding. Become inferior in sex.

The intrinsic viscosity [η] of polyethylene terephthalate is determined by the following method. That is,
Sample Polyethylene terephthalate was dissolved in o-chlorophenol at a concentration of 1 g / 100 ml, and the solution viscosity was measured using an Ubbelohde-type capillary viscometer at 25 ° C. Then, o-chlorophenol was gradually added to the low concentration side. Solution viscosity was measured and extrapolated to 0% concentration from these data.

The crystal melting temperature (melting point) of the polyethylene terephthalate obtained here is usually 21 when the temperature is raised at a rate of 10 ° C./min with a differential scanning calorimeter (DSC).
It is in the range of 0 to 265 ° C, preferably 220 to 260 ° C, and the glass transition temperature is usually in the range of 50 to 120 ° C, preferably 60 to 100 ° C.

The polyethylene naphthalate (b) having a constitutional unit represented by the general formula (2) used herein is 2,6-naphthalenedicarboxylic acid or its ester-forming derivative and ethylene glycol or its ester-forming derivative. Is obtained as a raw material. This polyethylene naphthalate contains the structural unit (b) represented by the general formula (2) in an amount of 70 mol% or more, preferably 8%, based on the total structural units.
It is desirable to contain 0 mol% or more, but 30 mol% of structural units other than the structural unit represented by the general formula (2).
It may be contained in an amount less than.

Specific examples of the dicarboxylic acid used in the constitutional units other than the constitutional unit represented by the general formula (2) include terephthalic acid, phthalic acid, isophthalic acid, 1,4-naphthalenedicarboxylic acid, 2, 7-naphthalenedicarboxylic acid, 2,
5-naphthalenedicarboxylic acid, diphenyldicarboxylic acid,
Examples thereof include aromatic dicarboxylic acids such as diphenoxyethanedicarboxylic acid, aliphatic dicarboxylic acids such as adipic acid, sebacic acid, azelaic acid and decanedicarboxylic acid, and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid.

Specific examples of the dihydroxy compound used in the constitutional unit other than the constitutional unit represented by the general formula (2) include trimethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, hexamethylene glycol, Aliphatic glycols such as dodecamethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol,
Examples thereof include alicyclic glycols such as cyclohexanedimethanol, bisphenols, hydroquinone, and 2,2-bis (4-β-hydroxyethoxyphenol) propane.

The polyethylene naphthalate as described above can be produced by a conventionally known production method. The polyethylene naphthalate thus obtained is substantially linear, which is confirmed by dissolving the obtained polyethylene naphthalate in a phenol / tetrachloroethane (equal weight mixed solution) mixed solution.

The intrinsic viscosity [η] of polyethylene naphthalate measured in o-chlorophenol at 25 ° C. was 0.
45-1.00 dl / g, preferably 0.50-0.9
0 dl / g, more preferably 0.55 to 0.70 dl
It is preferably in the range of / g. The intrinsic viscosity [η] of polyethylene naphthalate is measured in the same manner as in the case of polyethylene terephthalate.

The temperature rising crystallization temperature of the polyethylene naphthalate used in the present invention when heated with a differential scanning calorimeter (DSC) at a rate of 10 ° C./min is 150 ° C. or higher, preferably 160 ° C. to 230 ° C. ° C, particularly preferably 170-2
It is preferably in the range of 20 ° C.

Examples of the method for producing the polyester resin composition according to the present invention using these polyethylene terephthalate and polyethylene naphthalate include the following methods.

The polyethylene terephthalate having the structural unit (a) represented by the general formula (1) and the polyethylene naphthalate having the structural unit (b) represented by the general formula (2) obtained above are prepared in 260 The composition unit (c) represented by the general formula (3) is melt-kneaded with a melt-kneading machine at 30 ° C. to 330 ° C. for 30 seconds to 600 seconds to cause a transesterification reaction of polyethylene terephthalate and polyethylene naphthalate. When the amount of the constitutional unit (a) or (b), which is a small amount, is 100 mol, the polyester resin composition is produced in an amount of 30 to 200 mol based on this amount. The polyethylene terephthalate having the structural unit (a) represented by the general formula (1) obtained above and the structural unit (b) represented by the general formula (2). And polyethylene naphthalate are dry-blended, and then melt-kneaded at 260 ° C. to 330 ° C. for 30 seconds to 600 seconds in a molding machine such as an injection molding machine to cause a transesterification reaction between polyethylene terephthalate and polyethylene naphthalate. The amount of the structural unit (c) represented by the general formula (3) is 30 to 200 mol, when the amount of the structural unit (a) or (b) is 100 mol. A method for producing a polyester resin composition by producing the polyester resin composition according to claim 1.

A more specific manufacturing method in these cases will be described below. Examples of the method include a method in which polyethylene terephthalate and polyethylene naphthalate are melt-kneaded with a single-screw extruder, a twin-screw extruder, a kneader, a Banbury mixer, or the like. 330 ° C, preferably 270-30
The temperature is 0 ° C., and the time is usually 30 seconds to 600 seconds, preferably 60 seconds to 300 seconds, and particularly preferably 90 seconds to 240 seconds.

In the method (1), for example, polyethylene terephthalate and polyethylene naphthalate in the form of pellets are dry blended with a Henschel mixer, v-blender, ribbon blender, tumbler blender, etc., and then injection molding machine, blow molding machine, extrusion molding. Examples of the method include melt kneading in a molding machine such as a molding machine. In this case, the temperature during melt kneading is 260 to 330 ° C., preferably 270 to 290 ° C., and the time is usually 30 seconds to 60 ° C.
It is 0 second, preferably 60 seconds to 300 seconds, particularly preferably 90 seconds to 240 seconds.

The polyester resin composition according to the present invention includes, for example, polyethylene terephthalate having the structural unit (a) represented by the general formula (1) and the structural unit (b) represented by the general formula (2). It can also be prepared by melt-kneading the polyethylene naphthalate having the above and the copolyester having the structural unit (c) represented by the general formula (3). The polyethylene terephthalate having the structural unit (a) represented by the general formula (1) and the polyethylene naphthalate having the structural unit (b) represented by the general formula (2) used here are the same as those described above. .

The copolyester having the structural unit (c) represented by the general formula (3) is terephthalic acid or its ester-forming derivative, and 2,6-naphthalenedicarboxylic acid or its ethylene glycol-forming derivative. It is derived from ethylene glycol or its ester-forming derivative as a raw material.

This copolyester has the general formula (3)
The constitutional unit other than the constitutional unit represented by may be contained in an amount of less than 20 mol%. Such a copolyester can be produced by a conventionally known production method.

The intrinsic viscosity [η] of the copolymerized polyester obtained as described above is in the range of 0.5 to 1.0 dl / g, preferably 0.6 to 0.8 dl / g. desirable.

A method for producing a polyester resin composition according to the present invention using these polyethylene terephthalate, polyethylene naphthalate and a copolyester is, for example, after mixing polyethylene terephthalate, polyethylene naphthalate and a copolyester, A method of melt-kneading can be mentioned.

In the method for producing a polyester resin composition according to the present invention, a crosslinking agent, a heat resistance stabilizer, a weather resistance stabilizer, an antistatic agent, a lubricant, a mold release agent, an inorganic filler may be used during or after the above steps. Various compounding agents such as pigment dispersants, pigments or dyes may be added.

Polyester Preform The polyester preform according to the present invention can be obtained by subjecting the above polyester resin composition to a conventionally known method such as injection molding or extrusion molding.

Further, as described above, in the method of dry blending polyethylene terephthalate and polyethylene naphthalate to obtain the resin composition, after dry blending, the preform is directly melt-kneaded in an injection molding machine for preform molding. There is also a way to get it. This method is preferable from the economical point of view.

Polyester Bottle The polyester bottle according to the present invention can be molded by, for example, stretch blow molding a polyester resin composition or a polyester preform.

As the stretch blow molding method, the preform is stretched in the longitudinal direction within the temperature range suitable for stretching the preform, and then stretched by blow molding in the transverse direction (biaxial stretching). Blow method) and the like.

For example, in order to manufacture the polyester bottle of the present invention by such a biaxial stretch blow molding method, a bottomed parison molded by a usual injection molding machine,
Alternatively, the parison obtained by bottoming one end of the parison formed by an extrusion molding machine is blown at 90 to 140 ° C., which is the stretching suitable temperature of the polyester resin composition of the present invention, and is longitudinally oriented in the molding die. The moving rod is blown with a pressurized gas by 1.5 to 3.5 times, preferably 2 to 3 times in the vertical axis direction, and 2 to 5 times, preferably 3 times in the horizontal axis direction.
The method of stretching to 4.5 times can be illustrated. The pressurized gas used here includes air, nitrogen, steam and the like.

As a molding method by injection molding,
Either a two-stage system using a cold parison or a one-stage system using a hot parison may be used. The bottle thus obtained is subjected to a mold temperature of 100 to 250 ° C., preferably 110 to 200 ° C. for 1 second or longer,
The heat resistance may be improved by preferably heat setting for 3 seconds or more.

Since the polyester bottle according to the present invention is particularly excellent in transparency, heat resistance and ultraviolet ray blocking property, it can be used for various purposes. For example, seasonings, oils, alcoholic beverages, cosmetics and detergents. Etc. can be used as a container.

[0069]

The polyester resin composition according to the present invention is extremely excellent in transparency and heat resistance, and can block ultraviolet rays.

Furthermore, by using the method for producing a polyester resin composition according to the present invention, the polyester resin composition according to the present invention can be suitably produced. Further, since the polyester preform and the polyester bottle according to the present invention are formed from the polyester resin composition as described above, they are remarkably excellent in transparency, excellent in heat resistance, and can block ultraviolet rays. .

[0071]

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples within a range not impairing the object thereof.

In the present invention, the amount of the structural unit represented by the general formula (3) of the polyester resin composition, the transparency and heat resistance of the polyester bottle were measured as follows.

<Amount of Structural Unit (C)> In the present invention,
Structural units (a) and (b) in the polyester resin composition
The molar ratio of (c) is calculated as follows. That is, a molded article obtained from the polyester resin composition of the present invention, for example, a body part of a bottle-shaped polyester container is cut and dissolved in deuterated chloroform, and then FT-NMR (JEOL ( Ltd., NMRJMN-G
X270 type). On the chart, a structural unit (a) a peak (a) based on EG (ethylene glycol unit) -TA (terephthalic acid unit) -EG-TA,
Three peaks, a peak (b) based on the structural unit (b) EG-NDA (naphthalenedicarboxylic acid unit) -EG-NDA and a peak (c) based on the structural unit (c) EG-TA-EG-NDA, appear. Then, the peak area is measured. At this time, the area of the peak is determined by drawing a baseline for each peak as shown in FIG. 1 and calculating the area of each peak above the baseline. Thereby, the molar ratio of the units (a), (b) and (c) can be calculated.

FIG. 1 shows a typical chart when FT-NMR measurement is performed on an example of the composition of the present invention. <Transparency of polyester bottle> The body of the polyester bottle was cut, and a haze meter (NDH-20D, manufactured by Nippon Denshoku Co., Ltd.) was used to fill the inside and outside of the bottle with a solvent of cyclohexanol. After that, AST
The haze value was measured 3 times by the method according to MD 1003, and the average value was evaluated.

<Heat Resistance of Polyester Bottle> Heat resistance was evaluated by determining the glass transition point as follows. The glass transition point of a sample piece obtained by cutting the body of a polyester bottle formed from a polyester resin composition was measured by a differential scanning calorimeter (Prkin Elmer).
Manufactured by K.K.) and the temperature was raised at a rate of 10 ° C./min for measurement.

[0076]

Example 1 Polyethylene terephthalate (in o-chlorophenol at 25 ° C., [η] = 0.9 dl / g, melting point 2
55 ° C.) 90 parts by weight, and polyethylene naphthalate (phenol / tetrachloroethane mixed solution (equal weight mixed solution) at 25 ° C., [η] = 0.6 dl / g, melting point 26
5 ° C.) and 10 parts by weight using a tumbler blender, and then a molding machine (M-100A manufactured by Meiki Seisakusho Co., Ltd.)
To obtain a bottle-forming preform. At this time, the molding temperature was 270 to 290 ° C., and the residence time of the resin in the molding machine was 160 seconds.

Next, the preform obtained as described above was molded by a molding machine (LB-01 manufactured by CORPOPLAST) to obtain a biaxially stretched bottle. The stretching temperature at this time is 1
Matched at 10-150 ° C. The stretching ratio was 3.0 times in the longitudinal direction and 3.2 times in the lateral direction. Table 1 shows the physical properties of the obtained molded article.

[0078]

Examples 2 to 5 Molded articles were obtained in the same manner as in Example 1 except that the compounding amounts of polyethylene terephthalate and polyethylene naphthalate were changed as shown in Table 1.

[0079]

Comparative Example 1 A molded product was obtained in the same manner as in Example 1 except that the residence time in the molding machine was changed to 20 seconds.

[0080]

Comparative Example 2 A molded product was obtained in the same manner as in Example 2 except that the residence time in the molding machine was changed to 20 seconds.

[0081]

Comparative Example 3 A molded product was obtained in the same manner as in Example 1 except that only polyethylene terephthalate was used.

[0082]

[Table 1]

[Brief description of the drawings]

FIG. 1 is an NMR chart for calculating a transesterification rate.

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Claims (6)

[Claims] 1. A structural unit (a) represented by the following general formula (1); A structural unit (b) represented by the following general formula (2): A polyester resin composition comprising a structural unit (c) represented by the following general formula (3): When the amount of the structural unit (c) represented by the general formula (3) is 100 mol per 100 mol of the structural unit (a) or (b), whichever is smaller, the amount is 30 to 20
A polyester resin composition characterized by being in the range of 0 mol. 2. A polyethylene terephthalate having a constitutional unit (a) represented by the general formula (1) and a polyethylene naphthalate having a constitutional unit (b) represented by the general formula (2) are represented by the general formula (3). The amount of the structural unit (c) represented by) is 30 to 200 mol with respect to this amount when the amount of the structural unit (a) or (b), whichever is smaller, is 100 mol. The method for producing a polyester resin composition according to claim 1, which comprises melt-kneading so that 3. A polyethylene terephthalate having the structural unit (a) represented by the general formula (1) and a polyethylene naphthalate having the structural unit (b) represented by the general formula (2) are dry-blended and molded. 260 ℃ ~ 330 in the plane
The mixture is melt-kneaded at 30 ° C. for 600 seconds for 30 seconds to 600 seconds to cause a transesterification reaction of polyethylene terephthalate and polyethylene naphthalate to convert the structural unit (c) represented by the general formula (3) into the structural unit (a) or ( 3. The method for producing a polyester resin composition according to claim 2, wherein the amount of the structural unit having the smaller amount of b) is 30 to 200 mol when the amount is 100 mol. 4. A polyethylene terephthalate having a constitutional unit (a) represented by the general formula (1) and a polyethylene naphthalate having a constitutional unit (b) represented by the general formula (2) are contained at 260 ° C. to 330 ° C. In the above, by melt-kneading and transesterifying polyethylene terephthalate and polyethylene naphthalate, the structural unit (c) represented by the general formula (3) is reduced in either the structural unit (a) or (b). The method for producing a polyester resin composition according to claim 2, wherein the amount of the other structural unit is 100 to 100 moles, and the amount is 30 to 200 moles. 5. A polyethylene terephthalate having a structural unit (a) represented by general formula (1), a polyethylene naphthalate having a structural unit (b) represented by general formula (2), and a general formula (3). And a polyester having a structural unit (c) represented by the formula (2), wherein the amount of the structural unit (c) represented by the general formula (3) is the smaller of the structural unit (a) or (b). A method for producing a polyester resin composition, characterized in that, when the amount of the unit is 100 mol, the kneading is performed in a range of 30 to 200 mol based on this amount. 6. A polyester preform and a polyester bottle comprising the polyester resin composition according to claim 1.