JPH11310629A - New polyester and production of polyester - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polyester having excellent gas barrier properties, transparency, etc., slightly generating acetaldehyde, comprising a specific dicarboxylic acid constituent unit and a prescribed dial constituent unit by specifying an intrinsic viscosity, melting point, etc. SOLUTION: This polyester comprises (A) a dicarboxylic acid constituent unit composed of 40-99.5 wt.% based on the whole dicarboxylic acid constituent unit of a constituent unit from terephthalic acid, 0.5-60 wt.% of a constituent unit from a naphthalenedicarboxylic acid and 0-25 wt.% of a constituent unit from isophthalic acid and (B) a dial constituent unit composed of 95-100 wt.% based on the whole diol constituent unit of a constituent unit from ethylene glycol and 0-5 wt.% of a polyalkylene glycol constituent unit containing a 2-10C alkylene oxide chain, has 0.5-1.5 dL/g intrinsic viscosity and a melting point (Tm) satisfying the equation [1/527-0.0017.ln(1-(mI+mN)/200)]<-1> -273<Tm<=254 [mI is the ratio (mol.%) of a constituent unit from isophthalic acid in the total dicarboxylic acid constituent unit; mN is the ratio of a constituent unit from the naphthalenedicarboxylic acid]. The amount of the constituent units satisfies LNET>=0.5×mN.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a novel polyester and a method for producing the polyester, and more particularly, to a polyester excellent in gas barrier properties, transparency and heat resistance, and a method for producing the same.

[0002]

BACKGROUND OF THE INVENTION Saturated polyesters such as polyethylene terephthalate are widely used as containers such as bottles because of their excellent gas barrier properties, transparency and mechanical strength. In particular, the bottle obtained by biaxially stretch blow molding polyethylene terephthalate has excellent transparency, mechanical strength, heat resistance, and gas barrier properties,
It is widely used as a container (PET bottle) for filling beverages such as juice, soft drinks, and carbonated drinks.

[0003] Such a bottle is generally formed by injection molding a saturated polyester to form a preform having a plug portion and a body portion, and then inserting the preform into a mold having a predetermined shape and stretching the preform. It is manufactured by blow molding and stretching the body to form a bottle having a plug portion and a stretched body.

[0004] Usually, such a polyester bottle,
In particular, polyester bottles used for beverages such as juices are required to have heat resistance that can cope with heat sterilization of the contents, so the bottles are usually further heat-treated (heat-set) after blow molding to improve heat resistance. Let me.

[0005] However, the polyester bottle produced as described above has a non-stretched plug portion and is inferior in mechanical strength and heat resistance as compared with a stretched trunk portion. For this reason, usually, the plug portion of the preform is heated and crystallized before blow molding, or the plug portion of the bottle obtained by blow molding is heated and crystallized, and the mechanical strength of the plug portion, Heat resistance etc. are improved.

In recent years, bottles manufactured from polyester resins (particularly, polyethylene terephthalate) have tended to be miniaturized.
Since the area in contact with the bottle body per unit capacity is increased, the effect on the contents due to gas loss or permeation of oxygen from the outside becomes remarkable, and the preservation period of the contents is easily reduced. For this reason, polyester resins are required to have better gas barrier properties than before.

As an attempt to improve the heat resistance and gas barrier properties of such a polyester resin, it has been proposed to blend polyethylene naphthalate and the like with polyethylene terephthalate (see JP-A-8-34910). However, in such a blend of polyethylene terephthalate and polyethylene naphthalate, during melt-kneading at a high temperature performed to enhance compatibility, acetaldehyde is generated, and the taste of the contents filled in the container is reduced. In addition, there are problems such as a decrease in transparency.

For this reason, polyesters comprising a dicarboxylic acid component containing terephthalic acid as a main component, naphthalenedicarboxylic acid and ethylene glycol have been proposed, but the gas barrier properties are not always sufficient and acetaldehyde is generated. In some cases, the appearance of a polyester that is more excellent in gas barrier properties and generates less acetaldehyde is desired.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above prior art, and provides a polyester having excellent gas barrier properties, transparency and heat resistance and producing less acetaldehyde, and a method for producing the same. It is intended to be.

[0010]

SUMMARY OF THE INVENTION The polyester according to the present invention is a polyester comprising a dicarboxylic acid structural unit having terephthalic acid and naphthalenedicarboxylic acid as structural units and a diol structural unit having ethylene glycol as a structural unit. The structural unit derived from terephthalic acid is in the range of 40 to 99.5% by weight, and the structural unit derived from naphthalenedicarboxylic acid is in the range of 0.5 to 60% by weight, based on the dicarboxylic acid structural unit. The structural units derived from isophthalic acid are in the range of 0 to 25% by weight, and (ii) the structural units derived from ethylene glycol are in the range of 95 to 100% by weight, based on all the diol structural units, A polyalkylene glycol constituent unit having an alkylene oxide chain having 2 to 10 carbon atoms in a range of 0 to 5% by weight, Is in the range of 0.5 to 1.5 dl / g, and has a melting point (Tm) measured by a differential scanning calorimeter.
(° C.)) satisfies the following general formula [I], [1 / 527-0.0017 · ln (1- (m _I + m _N ) / 200)] ⁻¹ −273 <Tm ≦ 254 ... [I] ( In the formula, m _I is a ratio (mol%) of a structural unit derived from isophthalic acid in all dicarboxylic acid structural units, and m _N is a ratio of a structural unit derived from naphthalenedicarboxylic acid in all dicarboxylic acid structural units. The amount (L _NET (mol%)) of the structural unit linked in the order of naphthalenedicarboxylic acid-ethylene glycol-terephthalic acid (L _NET (mol%)) measured by ¹ H-NMR is represented by the following general formula [II L _NET ≧ 0.5 × m _N ... [II] (wherein, m _N represents the ratio (mol%) of the structural unit derived from naphthalenedicarboxylic acid in all the dicarboxylic acid structural units). It is characterized by:

The method for producing a polyester according to the present invention comprises:
[A] polyethylene terephthalate having a limiting viscosity of 0.3 to 0.8 dl / g before solid phase polymerization; 99 to 40% by weight; [B]
After blending 1 to 60% by weight of polyethylene naphthalate before solid phase polymerization with an intrinsic viscosity of 0.3 to 0.7 dl / g, the blend is solid phase polymerized.

The polyethylene naphthalate [B] comprises (i)
A dicarboxylic acid structural unit having a naphthalenedicarboxylic acid structural unit in a range of 100 to 55% by weight and an isophthalic acid structural unit in a range of 0 to 45% by weight; (ii) an ethylene glycol structural unit having a content of 100 to 90% by weight and a carbon number of 2 to 2; It is preferred that the polyalkylene glycol structural unit having 10 alkylene oxide chains be composed of a diol structural unit in the range of 0 to 10% by weight.

Further, the diol structural unit is composed of 99.999 to 90% by weight of ethylene glycol structural unit and 0.001 to 10% by weight of polyalkylene glycol structural unit having an alkylene oxide chain having 2 to 10 carbon atoms.
Is preferably within the range.

The polyalkylene glycol has a degree of polymerization of
Those in which (n) is in the range of 5 to 50 are preferred, and particularly preferred is polytetramethylene glycol. In the present invention, it is preferable to carry out solid phase polymerization after preliminarily crystallizing the above-mentioned blend by heating, and it is particularly preferable to carry out solid phase polymerization of a blend whose temperature-rising crystallization temperature is 190 ° C. or lower.

[0015]

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the novel polyester according to the present invention and the method for producing the polyester will be specifically described.

[Novel Polyester] The novel polyester according to the present invention comprises a dicarboxylic acid structural unit derived from terephthalic acid, naphthalenedicarboxylic acid and, if necessary, isophthalic acid, ethylene glycol and optionally 2 carbon atoms. And a diol constituent unit derived from a diol containing a polyalkylene glycol having an alkylene oxide chain of from 10 to 10.

In such a polyester, structural units derived from terephthalic acid are present in an amount of 40 to 99.5% by weight, preferably 50 to 95%, based on all dicarboxylic acid structural units.
% By weight, and the structural unit derived from naphthalenedicarboxylic acid is 0.5 to 60% by weight, preferably 5 to 60% by weight.
The content is in the range of 50% by weight, and the structural unit derived from isophthalic acid is in the range of 0 to 25% by weight. The structural unit derived from isophthalic acid may not be contained, but is more preferably contained in a proportion of 0.5 to 20% by weight.

In addition, as long as the object of the present invention is not impaired, all the dicarboxylic acid structural units may contain, for example, 15% by weight of a structural unit derived from a dicarboxylic acid other than the above.
It may be included in the following range.

Other dicarboxylic acids include aromatic dicarboxylic acids such as phthalic acid, diphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid, and fatty acids such as succinic acid, glutaric acid, adipic acid, sebacic acid, azelaic acid and decanedicarboxylic acid. And alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid.

As the diol structural unit, 95 to 100% by weight, preferably 95 to 100% by weight of a structural unit derived from ethylene glycol is used based on all diol structural units.
99.999% by weight, more preferably 96 to 99.9
The polyalkylene glycol structural unit having an alkylene oxide chain having 2 to 10 carbon atoms is in an amount of 0 to 5% by weight, preferably 0.001 to 5% by weight, and more preferably 0.01 to 4% by weight. % Is desirable.

The polyester of the present invention may not contain the above-mentioned polyalkylene glycol unit. However, when the polyester is contained in the above-mentioned proportion, it has a problem in terms of gas barrier properties, crystallization rate at elevated temperature, transparency, and thermal stability during molding. Is more preferable.

Such a polyalkylene glycol is
It is a conventionally known polyalkylene glycol having 2 carbon atoms.
It is produced by condensing an alkylene glycol of 10 to 10 by a known method.

The degree of polymerization (n) of such a polyalkylene glycol is desirably in the range of 5 to 50, preferably 10 to 45. As such a polyalkylene glycol, specifically, polyethylene glycol,
Examples include polypropylene glycol, polytetramethylene glycol, polyheptamethylene glycol, polyhexamethylene glycol, polyoctamethylene glycol, and the like. Among these, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, and polyoctamethylene glycol are preferable because of their excellent gas barrier properties, and polytetramethylene glycol is particularly preferable.

In addition, as long as the object of the present invention is not impaired, all the diol constituent units may contain constituent units derived from other diols, for example, in a range of 15% by weight or less.

Specific examples of other diols include aliphatic diols such as diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, butanediol, pentanediol, neopentyl glycol, hexamethylene glycol, dodecamethylene glycol, and cyclohexane. Alicyclic diols such as dimethanol, 1,3-bis (2-hydroxyethoxy)
Benzene, 1,2-bis (2-hydroxyethoxy) benzene,
Diols containing an aromatic group such as 1,4-bis (2-hydroxyethoxy) benzene, aromatic diols such as bisphenols, hydroquinone, and 2,2-bis (4-β-hydroxyethoxyphenyl) propane. No.

These diols may be used in combination of two or more. Of these, diethylene glycol and cyclohexanedimethanol are preferred. Furthermore, as long as the object of the present invention is not impaired, trimesic acid, polyvalent carboxylic acids having three or more carboxy groups such as pyromellitic anhydride, glycerin, 1,1,1-trimethylolethane, 1,1, It may contain structural units derived from polyhydric alcohols having three or more hydroxy groups, such as 1,1-trimethylolpropane, 1,1,1-trimethylolmethane, and pentaerythritol.

The novel polyester according to the present invention as described above has an intrinsic viscosity [η] measured in o-chlorophenol at 25 ° C. of 0.5 to 1.5 dl / g, preferably 0.1 to 1.5 dl / g.
It is desirable to be in the range of 6 to 1.2 dl / g.

The novel polyester according to the present invention has a melting point (Tm) measured by a differential scanning calorimeter.
(° C.)) satisfies the following general formula [I]. [1 / 527-0.0017 · ln (1- (m _I + m _N ) / 200)] ⁻¹ −273 <Tm ≦ 254 ... [I] (where m _I is from isophthalic acid in all dicarboxylic acid constituent units) _MN is the ratio (mol%) of the structural unit derived from naphthalenedicarboxylic acid in all the dicarboxylic acid structural units.) The melting point (Tm (° C.)) of the polyester preferably satisfies the following general formula [I ′].

[1 / 527-0.0017 · ln (1- (m _I + m _N ) / 200)] ⁻¹ −270 <Tm ≦ 254 ... [I ′] The novel polyester according to the present invention is ¹ H -NMR
The amount of structural units linked in the order of naphthalenedicarboxylic acid-ethylene glycol-terephthalic acid (L _NET (mol%)) measured by the following formula satisfies the following general formula [II]: L _NET ≧ 0.5 × m _N ... [II] (in the formula, m _N represents a ratio (mol%) of a structural unit derived from naphthalenedicarboxylic acid in all the dicarboxylic acid structural units.) In the general formula [II], preferably, L _NET ≧ 0 .55 × m
_N , more preferably 1.8 × m _N ≧ L _NET ≧ 0.6 ×
m _N is desirable.

The amount (L _NET ) of the structural units linked in the order of naphthalenedicarboxylic acid-ethylene glycol-terephthalic acid in the polyester is determined as follows.

That is, after dissolving the polyester of the present invention and the molded product obtained from the polyester in deuterated chloroform, use FT-NMR (manufactured by JEOL Ltd., NMRJMN-GX270 type) at 45 ° C. Measure.

On the chart, (1) terephthalic acid (also
Is isophthalic acid) -ethylene glycol-terephthalic acid
(Or isophthalic acid)
(2) naphthalenedicarboxylic acid-ethylene glycol
Constituent units linked in the order of coal-naphthalenedicarboxylic acid
And (3) naphthalenedicarboxylic acid
-Ethylene glycol-terephthalic acid
A peak based on the unit appears. Measure this peak area
From the ratio of each peak area
-Ethylene glycol-terephthalic acid
The amount of the composition unit (L _NET) Is calculated.

In the case of such a polyester, the haze value of a 5 mm-thick rectangular plate obtained at an injection molding temperature of 280 ° C. and a mold temperature of 10 ° C. is preferably 20% or less,
More preferably, it is 18% or less.

The polyester according to the present invention preferably has an acetaldehyde content of 20 ppm or less, more preferably 18 ppm or less.

The polyester according to the present invention is
It can be obtained by a manufacturing method described later. The polyester according to the present invention further contains, if necessary, additives usually added to the polyester, for example, a colorant, an antioxidant, an oxygen absorber, an ultraviolet absorber, an antistatic agent, a flame retardant, and the like. Is also good. Furthermore, PET as needed
Recycled products may be included. Furthermore, if necessary, resins other than polyester, for example, polyethylene, ionomer, polypropylene, and polyester elastomer may be contained.

Such a polyester is usually pelletized into polyester pellets, blended with other resins and additives as necessary, and then mixed with various kinds of preforms, bottles, (stretched) films, sheets and the like. It can be used as a molding material. In addition, these molded articles have a laminate in which at least one layer is a layer molded from the polyester of the present invention, or a laminate in which at least one layer is a layer formed from a blend of the polyester of the present invention and another resin. It may be. This layer may be used for any of the inner layer, the outer layer, and the intermediate layer.

Examples of the resin constituting the other layer include polyesters such as polyethylene terephthalate and polyethylene isophthalate, polyamides such as nylon 6, and ethylene / vinyl acetate copolymer.
Of these, polyethylene terephthalate is preferred.

The bottle made from such polyester pellets has excellent gas barrier properties, transparency and heat resistance. Further, since the generation of acetaldehyde is small, the taste of contents such as juice does not decrease.

Next, a method for producing the polyester according to the present invention will be described. [Method for Producing Polyester] The method for producing the polyester according to the present invention comprises: [A] polyethylene terephthalate having an intrinsic viscosity of 0.3 to 0.8 dl / g before solid phase polymerization; 99 to 40% by weight
And [B] polyethylene naphthalate before solid phase polymerization having an intrinsic viscosity of 0.3 to 0.7 dl / g; 1 to 60% by weight, and then the blend is subjected to solid state polymerization.

Polyethylene Terephthalate [A] The polyethylene terephthalate used in the present invention comprises a dicarboxylic acid unit derived from terephthalic acid or an ester derivative thereof, and a diol unit derived from ethylene glycol or an ester derivative thereof.

The dicarboxylic acid unit of the polyethylene terephthalate [A] contains the terephthalic acid unit in an amount of 80 mol% or more, preferably 85 to 100 mol%, when the unit is 100 mol%.

Examples of other dicarboxylic acids which may be contained in an amount of 20 mol% or less include phthalic acid (orthophthalic acid), isophthalic acid, 2,6-naphthalenedicarboxylic acid, and 2,7-naphthalene Aromatic dicarboxylic acids such as dicarboxylic acid, 2,5-naphthalenedicarboxylic acid, diphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid, and aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, sebacic acid, azelaic acid, and decanedicarboxylic acid Acids and alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid are exemplified.

These dicarboxylic acids may be ester derivatives thereof, or may be used in combination of two or more. As the other dicarboxylic acid, isophthalic acid is preferable among them.

When the diol unit of polyethylene terephthalate [A] is 100 mol%, the ethylene glycol unit is 80 mol% or more, preferably 85 to 100 mol%.
Desirably, it is contained in an amount of mol%.

Examples of other diols which may be contained in an amount of 20 mol% or less include diethylene glycol, triethylene glycol, tetraethylene glycol, trimethylene glycol, propylene glycol, butanediol, pentanediol, and the like. Aliphatic glycols such as neopentyl glycol, hexamethylene glycol, dodecamethylene glycol, alicyclic glycols such as cyclohexane dimethanol, 1,3-bis (2
Glycols containing aromatic groups such as (-hydroxyethoxy) benzene, 1,2-bis (2-hydroxyethoxy) benzene, 1,4- (2-hydroxyethoxy) benzene, bisphenols, hydroquinone, 2,2-bis And aromatic diols such as (4-β-hydroxyethoxyphenyl) propane.

These diols may be ester derivatives thereof. These diols may be a combination of two or more. As other diols, diethylene glycol, cyclohexanedimethanol and the like are preferable among these.

The polyethylene terephthalate used in the present invention is derived from a polycarboxylic acid having three or more carboxyl groups or a polyfunctional diol having three or more hydroxy groups as long as the object of the present invention is not impaired. May be contained, for example, trimesic acid, polyfunctional carboxylic acids such as pyromellitic anhydride, glycerin, 1,1,1-trimethylolethane, 1,1,1
It may contain units derived from polyhydric alcohols such as 1-trimethylolpropane, 1,1,1-trimethylolmethane, and pentaerythritol.

The polyethylene terephthalate used in the present invention is substantially linear, which is confirmed by the dissolution of polyethylene terephthalate in o-chlorophenol.

The polyethylene terephthalate used in the present invention has an intrinsic viscosity [η] measured at 25 ° C. in o-chlorophenol of 0.3 to 0.8 dl / g, preferably 0.35 to 0.8 dl / g.
It is preferably 0.75 dl / g, after the liquid phase polymerization and before the solid phase polymerization.

The melting point of polyethylene terephthalate measured by a differential scanning calorimeter (DSC, heating rate 10 ° C./min) is usually 210 to 265 ° C., preferably 220 to 260 ° C., and the glass transition temperature is , Usually 50 to 120 ° C, preferably 60
Desirably, it is 〜100 ° C.

The polyethylene terephthalate used in the present invention may be pre-crystallized if necessary. The pre-crystallization can be usually performed by heating at 130 to 200 ° C. for about 1 to 360 minutes.

Such a polyethylene terephthalate can be produced by a conventionally known method. For example, after the dicarboxylic acid and the diol are directly esterified, a germanium compound such as germanium dioxide, antimony trioxide, acetic acid and the like are used. Melt polymerization was performed in the presence of a polycondensation catalyst such as an antimony compound such as antimony, or a titanium compound such as titanium tetraalkoxide, or a transesterification reaction was performed between a dicarboxylic acid ester and a diol in the presence of a transesterification catalyst. Thereafter, it can be produced by melt polymerization in the presence of a polycondensation catalyst such as a germanium compound such as germanium dioxide, antimony trioxide, an antimony compound such as antimony acetate, and a titanium compound such as titanium tetraalkoxide.

[B] Polyethylene Naphthalate The polyethylene naphthalate [B] used in the present invention is:
It contains a dicarboxylic acid structural unit derived from naphthalenedicarboxylic acid and a diol structural unit derived from ethylene glycol.

Among them, polyethylene naphthalene containing a dicarboxylic acid structural unit derived from naphthalenedicarboxylic acid and isophthalic acid and a diol structural unit derived from ethylene glycol and a polyalkylene glycol having an alkylene oxide chain having 2 to 10 carbon atoms. A phthalate copolymer is preferred.

Such a polyethylene naphthalate [B]
Is 100 to 55% by weight, preferably 100 to 75% by weight of a naphthalenedicarboxylic acid structural unit based on all dicarboxylic acid structural units.
% By weight, more preferably in the range of 99 to 80% by weight.
It is desirable to contain it in the range of 0 to 45% by weight, preferably 0 to 25% by weight, more preferably 1 to 20% by weight.

Polyethylene naphthalate [B] having a dicarboxylic acid structural unit having such a composition has particularly excellent gas barrier properties, and also has excellent moldability and thermal stability during molding.

The polyethylene naphthalate [B] used in the present invention contains less than 15 mol% of dicarboxylic acid structural units other than 2,6-naphthalenedicarboxylic acid and isophthalic acid as long as the object of the present invention is not impaired. May be contained.

Examples of other dicarboxylic acids which may be contained in an amount of less than 15 mol% include terephthalic acid, phthalic acid (orthophthalic acid), 2,7-naphthalenedicarboxylic acid, and 2,5-naphthalene. Aromatic dicarboxylic acids such as dicarboxylic acid, diphenyldicarboxylic acid, diphenoxyethanedicarboxylic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, azelaic acid, aliphatic dicarboxylic acids such as decanedicarboxylic acid, cyclohexanedicarboxylic acid, etc. Alicyclic dicarboxylic acids and the like.

These dicarboxylic acids may be ester derivatives thereof. In addition, these dicarboxylic acids are 2
It may be used in combination of more than one species. As the other dicarboxylic acid, terephthalic acid is preferable among these.

The polyethylene naphthalate [B] used in the present invention contains ethylene glycol structural units in an amount of 100 to 90% by weight, preferably 99.90%, based on all diol structural units.
999 to 90% by weight, more preferably 99.99 to 92% by weight, more preferably 99.9 to 94% by weight, particularly preferably 99.5 to 95% by weight.
It is desirable to include it in the range of weight%.

Further, the polyethylene naphthalate [B] preferably contains a polyalkylene glycol structural unit having an alkylene oxide chain having 2 to 10 carbon atoms. % By weight, preferably 0.001 to 10% by weight, more preferably
0.01 to 8% by weight, more preferably 0.1 to 6% by weight, particularly preferably
More preferably, it is contained in the range of 0.5 to 5% by weight.

When the content of the polyalkylene glycol constituent unit is 0.001% by weight or more, the gas barrier property and the temperature-increasing crystallization rate of polyethylene naphthalate [B] are sufficient, and the content of the unit is 10% by weight. % Or less is desirable because it is excellent in transparency and thermal stability during molding.

The polyalkylene glycol having an alkylene oxide chain having 2 to 10 carbon atoms is a conventionally known polyalkylene glycol. Such a polyalkylene glycol is obtained by converting an alkylene glycol having 2 to 10 carbon atoms into a known alkylene glycol. It is obtained by co-condensing according to the method.

The polyalkylene glycol preferably has a polymerization degree (n) in the range of 5 to 50, preferably 10 to 45. As such a polyalkylene glycol,
Specific examples include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyheptamethylene glycol, polyhexamethylene glycol, polyoctamethylene glycol, and the like.
Among these, polypropylene glycol, polytetramethylene glycol, polyhexamethylene glycol, and polyoctamethylene glycol are preferred because of their excellent gas barrier properties, and polytetramethylene glycol is particularly preferred.

The polyethylene naphthalate copolymer [B] used in the present invention includes ethylene glycol and a poly (alkylene oxide chain having 2 to 10 carbon atoms) as long as the object of the present invention is not impaired. A diol constituent unit other than the alkylene glycol may be contained in an amount of less than 15 mol%.

As other diols which may be contained in an amount of less than 15 mol%, specifically, other diols as shown for the above-mentioned polyethylene terephthalate [A] can be mentioned.

As other diols, diethylene glycol, 1,3-bis (2-hydroxyethoxy) benzene and the like are preferable among these. Further, polyethylene naphthalate [B] used in the present invention may be a polycarboxylic acid having 3 or more carboxyl groups as shown in polyethylene terephthalate [A], or a polycarboxylic acid having 3 or more as long as the object of the present invention is not impaired. It may contain a unit derived from a polyhydric alcohol having a hydroxy group as described above, and specifically, a unit derived from a polyhydric carboxylic acid and / or a unit derived from a polyhydric alcohol may be independently formed. 0.05 to 0.4 mol%, preferably 0.1 to 0.35 mol%, more preferably 100 to 100 mol% of dicarboxylic acid units
It may be contained in an amount of 0.2 to 0.35 mol%.

The intrinsic viscosity [η] of the polyethylene naphthalate [B] used in the present invention measured in o-chlorophenol at 25 ° C. is 0.3 to 0.7 dl / g, preferably 0.35 to 0.65.
Desirably dl / g. Differential scanning calorimeter for polyethylene naphthalate [B] (DSC, heating rate 10 ° C / min)
Melting point measured at 220 to 280 ° C., preferably 230
℃ ~ 275 ℃, the glass transition temperature is usually 90 ~ 140 ℃,
Preferably it is 100-130 degreeC.

Such polyethylene naphthalate [B]
May be pre-crystallized if necessary. The pre-crystallization can be performed usually by heating at 160 to 230 ° C. for about 1 to 360 minutes.

The polyethylene naphthalate [B] used in the present invention can be produced by a conventionally known method. For example, after directly diesterifying the dicarboxylic acid and diol, germanium such as germanium dioxide can be used. Compounds, antimony trioxide, antimony compounds such as antimony acetate, melt polymerization in the presence of polycondensation catalysts such as titanium compounds such as titanium tetraalkoxide, or in the presence of transesterification catalysts for esters and diols of dicarboxylic acids and diols After transesterification with, germanium compounds such as germanium dioxide,
It can be produced by melt polymerization in the presence of a polycondensation catalyst such as antimony compounds such as antimony trioxide and antimony acetate, and titanium compounds such as titanium tetraalkoxide.

[Polyester blend] In the present invention,
The above polyethylene terephthalate [A]; 99 to 40% by weight,
Preferably, 98 to 50% by weight is blended with the above polyethylene naphthalate [B]; 1 to 60% by weight, preferably 2 to 50% by weight.

The blend was prepared by mixing polyethylene terephthalate [A] and polyethylene naphthalate so as to have the above composition.
After blending with [B], the mixture is melt-kneaded at 260 to 330 ° C. for 30 to 300 seconds. The blend after kneading,
It is chipped by an extruder or the like. The average particle size of the chips is preferably 2.0 to 5.0 mm.

When polyethylene terephthalate [A] and polyethylene naphthalate [B] are blended as described above, a transesterification catalyst, a lubricant and the like may be added as necessary.

Examples of the transesterification catalyst include germanium dioxide, antimony trioxide, antimony acetate, titanium tetrabutoxide and the like. Such a transesterification catalyst is used in an amount of 0.0005 to 0.1 with respect to 100 parts by weight of the blend.
It is desirable that it be contained in an amount of from about 0.001 to about 0.05 parts by weight.

Specific examples of the lubricant include magnesium stearate and calcium stearate.
Such a lubricant is used in an amount of 0.000 parts per 100 parts by weight of the blend.
It is desirable to contain 5 to 0.1 part by weight, preferably 0.001 to 0.05 part by weight.

The temperature-rise crystallization temperature (Tcc) of the thus obtained blend is preferably 190 ° C. or lower, preferably 180 ° C. or lower, more preferably 120 to 170 ° C. In addition,
The temperature rise crystallization temperature (Tcc) is measured as follows.

Specifically, using a DSC-7 type differential scanning calorimeter manufactured by PerkinElmer, about 10 mg of a sample from the center of a polyester blend chip dried at about 140 ° C. under a pressure of about 5 mmHg for about 5 hours or more. The thin section is sealed in a liquid aluminum pan under a nitrogen atmosphere and measured. The measurement conditions were as follows: First, the temperature was raised rapidly from room temperature at a rate of 320 ° C / min.
After melting and holding at 90 ° C for 10 minutes, rapidly cool to room temperature at a rate of 320 ° C / min, hold for 10 minutes, and then detect the exothermic peak detected when heating at a rate of 10 ° C / min. Find the peak temperature.

The intrinsic viscosity of the obtained blend measured in o-chlorophenol at 25 ° C. is 0.3 to 0.9 dl /
g, preferably 0.35 to 0.85 dl / g. [Solid State Polymerization of Blend] The chip of the blend thus obtained is then subjected to solid state polymerization.

In the solid phase polymerization, usually, chips of the blended product are obtained.
It is carried out by heating at 180 to 230 ° C, preferably 190 to 220 ° C. At the time of solid-phase polymerization, the chips of the blend are desirably dried, and therefore, the chips of the blend may be dried at 80 to 180 ° C. in advance. In the present invention, the blend may be pre-crystallized before the solid phase polymerization. Pre-crystallizing the blend from 120 to 2
It is carried out by heating at 00C, preferably 140-180C.

The polyester thus obtained was heated at 250 ° C.
-Intrinsic viscosity measured in chlorophenol is 0.5 ~
It is 1.5 dl / g, preferably 0.6 to 1.2 dl / g, and is desirably 1.1 to 2.5 times, preferably 1.2 to 2.0 times, the intrinsic viscosity of the blend before solid phase polymerization.

Further, in the present invention, the obtained solid phase polymer may be subjected to a hot water treatment. The hot water treatment is performed by immersing the obtained solid phase polymer in hot water at 70 to 120 ° C. for 1 to 360 minutes.

The polyester obtained by the production method according to the present invention contains, if necessary, additives usually added to the polyester, for example, a colorant, an antioxidant, an ultraviolet absorber, an antistatic agent and a flame retardant. It may be.

The polyester obtained by the production method according to the present invention can be used as a material for various molded articles such as preforms, bottles, (stretched) films and sheets. Bottles made of such polyester are excellent in gas barrier properties, transparency and heat resistance. Further, since the generation of acetaldehyde is small, the taste of contents such as juice does not decrease.

[0084]

According to the present invention, it is possible to obtain a polyester which is excellent in gas barrier properties, transparency and heat resistance and generates little acetaldehyde.

[0085]

EXAMPLES Hereinafter, the present invention will be described more specifically based on examples, but the present invention is not limited to these examples.

In the examples, each characteristic was measured as follows. Prepare a 1 g / dl sample solution using the intrinsic viscosity o-chlorophenol solvent, measure the solution viscosity using an Ubbelohde capillary viscometer at 25 ° C, and then gradually add o-chlorophenol to reduce the solution viscosity. Measure the solution viscosity on the concentration side, and from those data
Extrapolated to 0% concentration.

Carbon dioxide gas permeability coefficient (gas barrier property) Gas permeability measurement device GPM- manufactured by GL Sciences Corporation
Using 250, the measurement was performed under the conditions of 23 ° C. and 60% relative humidity.

The film used for the measurement was produced as follows. Stretched film: Using a press molding machine with a mold temperature of 290 ° C
A film having a thickness of 0.3 mm was produced, and this film was rapidly cooled at a cooling mold temperature of 0 ° C. to obtain an amorphous film. The amorphous film is then brought to a glass transition temperature (Tg) of
Simultaneous biaxial stretching was performed 3 × 3 times at a temperature higher by 30 ° C. to obtain a stretched film.

Transparency (Haze Value) A 5 mm-thick square plate was formed from the dried polymer using an injection molding machine at a cylinder temperature of 280 ° C. at a mold temperature of 10 ° C., and the transparency of the molded product was determined by the haze value (white). (Light diffuse reflectance of light).

Acetaldehyde content : About 2 g of a test piece is sampled from a molded sample of a sample and freeze-ground by a freeze-mill of SPEX. 1 g of the obtained sample powder is placed in a vial, 2 ml of distilled water is added, and the water and the sample powder are mixed well. After capping, the vial is heated at 120 ° C. for 1 hour. After heating, the mixture was cooled in ice water, and 5 μl of the supernatant was measured with a gas chromatograph (GC-6A, manufactured by Shimadzu Corporation).

L _NET Identification After dissolving the obtained polyester in deuterated chloroform, FT-NMR (manufactured by JEOL Ltd., NMR) at 45 ° C.
JMN-GX270 type).

On the chart, peaks based on (1) terephthalic acid (or isophthalic acid) -ethylene glycol-terephthalic acid (isophthalic acid) -connected structural units, (2) naphthalenedicarboxylic acid-ethylene glycol-naphthalene A peak based on the structural unit linked in the order of dicarboxylic acid and (3) a peak based on the structural unit linked in the order of naphthalenedicarboxylic acid-ethylene glycol-terephthalic acid appear. Measure this peak area,
From the ratio of the peak areas, the amount of structural units linked in the order of naphthalenedicarboxylic acid-ethylene glycol-terephthalic acid (L _NET : mol%) is calculated.

Measurement of Melting Point Using a DSC-7 differential scanning calorimeter manufactured by Perkin Elmer, about 10 mg of a sample was obtained from the center of a polyester chip dried at about 140 ° C. under a pressure of about 5 mmHg for about 5 hours or more. Of the sample, sealed in a nitrogen pan in a liquid aluminum pan, and measured.

The measurement conditions were as follows: first, the temperature was rapidly raised from room temperature at a rate of 320 ° C./min, and the mixture was melted and held at 290 ° C. for 10 minutes, and then rapidly cooled to room temperature at a rate of 320 ° C./min. The temperature at the end of the endothermic peak detected when the temperature is held for 10 minutes and then at a rate of 10 ° C./min. This peak temperature is defined as the melting point.

[0095]

Example 1 High-purity polyethylene terephthalate (A-1) 332 g of terephthalic acid and 143 g of ethylene glycol
Was prepared, and 0.042 g of germanium dioxide and 0.080 g of phosphoric acid were added thereto. This slurry was heated to a temperature of 255 ° C. under pressure (absolute pressure: 1.7 kg / cm ² ), and an esterification reaction was carried out until an esterification ratio became 95%, to produce a low polymer. Then, under a reduced pressure of 1 torr, 2
The low polymer is melt-polymerized at a temperature of 80 ° C. to produce a prepolymer of polyethylene terephthalate (A-1) having an intrinsic viscosity of 0.615 dl / g, which is extruded from a nozzle into a strand shape, cut and cut, and A 2.5 mm, 3.5 mm high cylindrical tip was used. The heated crystallization temperature of this prepolymer blend was 158 ° C.

The polyethylene naphthalate copolymer (B-
1) 2,6-dimethylnaphthalate 228g, dimethyl isophthalate
19 g, ethylene glycol 143 g, and average molecular weight 1000
Of 1.9 g of polytetramethylene glycol was prepared, and 0.25 g of manganese acetate tetrahydrate was charged into a reactor, and reacted at 240 ° C. for 3 hours under a nitrogen atmosphere at normal pressure with stirring. Methanol produced by this reaction was constantly distilled out of the system. Next, 0.042 g of germanium dioxide and 0.080 g of phosphoric acid were added, and the low polymer was melt-polymerized at a temperature of 285 ° C. under a reduced pressure of 1 torr,
Generate a prepolymer of polyethylene naphthalate copolymer (B-1) with an intrinsic viscosity of 0.643 dl / g, extrude it into a strand shape from a nozzle, cut it, and have a diameter of 2.5 mm and a height of 2.5 mm.
A 3.5 mm cylindrical tip was used.

Polyester Blend The prepolymer of polyethylene naphthalate copolymer (B-1) was 10 parts by weight with respect to 90 parts by weight of the polyethylene terephthalate (A-1) prepolymer obtained above. The dry-blended material was melt-kneaded at a molding temperature of 295 ° C. using a Thermo Co., Ltd. 20 mmφ single-screw extruder with a residence time of 120 seconds in the cylinder, extruded from the nozzle into a strand, cut and cut to a diameter of 2.5 mm, A 3.5 mm high cylindrical tip was used. The heated crystallization temperature of this prepolymer blend was 150 ° C.

Solid Phase Polymerization The chips obtained above were heated at 170 ° C. for 2 hours under a nitrogen stream.
After pre-crystallization by heating for a period of time, solid-state polymerization was further performed by heating at 210 ° C. for 16 hours.

The polyester thus obtained is
The limiting viscosity was 0.835 dl / g. Also this polyester
The carbon dioxide permeability coefficient of the stretched film obtained from 9.1 cc
mm / m ^Two・ Day ・ atm, haze value is 9.8%, naphthalene range
In the order of carboxylic acid-ethylene glycol-terephthalic acid
The amount of linked constituent units (L_NET) Is 9.2 mol%.
Cetaldehyde content was 11 ppm.

[0100]

Example 2 Polyethylene naphthalate copolymer (B-
2) 2,6-dimethylnaphthalate 228 g, dimethyl isophthalate
19 g, ethylene glycol 143 g, and average molecular weight 1000
A slurry composed of 1.9 g of polytetramethylene glycol was prepared, and this and 0.25 g of manganese acetate tetrahydrate were charged into a reactor, and reacted while stirring at 240 ° C. for 3 hours under a normal pressure under a nitrogen atmosphere. . Methanol produced by this reaction was constantly distilled out of the system. Next, 0.042 g of germanium dioxide and 0.080 g of phosphoric acid were added, and the low polymer was melt-polymerized at a temperature of 280 ° C. under a reduced pressure of 1 torr to obtain a polyethylene naphthalate copolymer having an intrinsic viscosity of 0.623 dl / g. Generate a prepolymer of the polymer (B-2), extrude it into a strand shape from a nozzle and cut it, 2.5 mm in diameter,
A 3.5 mm high cylindrical tip was used.

Polyester Blend Polyethylene terephthalate (A-1) produced in Example 1
The dry blended so that the prepolymer of the polyethylene naphthalate copolymer (B-2) was 40 parts by weight with respect to 60 parts by weight of the prepolymer of
Using a φ single-screw extruder, melt-kneaded at a molding temperature of 295 ° C and a residence time of 120 seconds in the cylinder, extruded from the nozzle into a strand, and cut into cylindrical chips with a diameter of 2.5 mm and a height of 3.5 mm. . The heated crystallization temperature of this prepolymer blend was 158 ° C.

Solid Phase Polymerization The chip obtained above was heated at 170 ° C. for 2 hours under a nitrogen stream.
After pre-crystallization by heating for a period of time, solid-state polymerization was further performed by heating at 210 ° C. for 16 hours.

The polyester thus obtained is
The limiting viscosity was 0.842 dl / g. Also this polyester
The carbon dioxide permeability coefficient of the stretched film obtained from 5.8cc
mm / m ^Two・ Day ・ atm, haze value is 9.2%, naphtha
Range carboxylic acid-ethylene glycol-terephthalic acid
Of the structural units connected in the order of (L_NET) Is 26.8 mol%
Yes, the acetaldehyde content was 13 ppm.

[0104]

Example 3 Polyethylene terephthalate (A-2) 388 g of dimethyl terephthalate and ethylene glycol 13
A slurry composed of 6 g was prepared, and 0.049 g of manganese acetate tetrahydrate was added thereto, and the mixture was heated to 180 ° C. under normal pressure and reacted until the transesterification rate reached 95% to produce a low polymer. did. An additional 0.042 g of germanium dioxide and 0.08
After adding 0 g of phosphoric acid, the low polymer was melt-polymerized at a temperature of 280 ° C. under a reduced pressure of 1 torr, and the intrinsic viscosity was 0.598 dl /.
g of polyethylene terephthalate (A-2) prepolymer was produced, extruded from a nozzle into a strand, and cut to obtain a cylindrical chip having a diameter of 2.5 mm and a height of 3.5 mm.
The preheated crystallization temperature of this prepolymer blend is 153 ° C
Met.

The polyethylene naphthalate copolymer (B-
3) 2,6-dimethylnaphthalate 228 g, dimethyl isophthalate
19 g, ethylene glycol 143 g, and average molecular weight 2000
A slurry composed of 1.9 g of polytetramethylene glycol was prepared, and 0.49 g of manganese acetate tetrahydrate was added thereto,
The mixture was heated to 180 ° C. under a normal pressure under a nitrogen atmosphere to carry out a reaction until the transesterification rate reached 95%, thereby producing a low polymer.
After further adding 0.042 g of germanium dioxide and 0.080 g of phosphoric acid, under a reduced pressure of 1 torr, the low polymer was melt-polymerized at a temperature of 280 ° C. to obtain a polyethylene naphthalate having an intrinsic viscosity of 0.598 dl / g. A prepolymer of the copolymer (B-3) was produced, extruded from a nozzle into a strand, and cut to obtain a cylindrical chip having a diameter of 2.5 mm and a height of 3.5 mm.

Polyester Blend The prepolymer of the polyethylene naphthalate copolymer (B-3) was adjusted to 10 parts by weight with respect to 90 parts by weight of the obtained polyethylene terephthalate (A-2) prepolymer. The dry-blended product was melt-kneaded at a molding temperature of 295 ° C with a residence time of 90 seconds in the cylinder using a 20 mmφ single-screw extruder manufactured by Thermo Co., and extruded into a strand form from a nozzle, cut into a 2.5 mm diameter, high A 3.5 mm cylindrical tip was used. The elevated crystallization temperature of this prepolymer blend is
156 ° C.

Solid Phase Polymerization The chips obtained above were heated at 170 ° C. for 2 hours under a nitrogen stream.
After pre-crystallization by heating for a period of time, solid-state polymerization was further performed by heating at 210 ° C. for 16 hours.

The intrinsic viscosity of the polyester thus obtained was 0.826 dl / g. The carbon dioxide permeability coefficient of the stretched film obtained from this polyester is 10.1cc
Mm / m ² · day · atm, the haze value is 8.6%, the amount of structural units linked in the order of naphthalenedicarboxylic acid-ethylene glycol-terephthalic acid (L _NET ) is 7.8 mol%, and acetaldehyde The content was 10 ppm.

[0109]

Example 4 Polyethylene naphthalate copolymer (B-
4) 186 g of 2,6-dimethylnaphthalate, dimethyl isophthalate
38 g, ethylene glycol 143 g, and average molecular weight 1000
A slurry composed of 1.9 g of polytetramethylene glycol was prepared, and 0.49 g of manganese acetate tetrahydrate was added thereto,
The mixture was heated to 180 ° C. under a normal pressure under a nitrogen atmosphere to carry out a reaction until the transesterification rate became 95%, thereby producing a low polymer. Further, 0.042 g of germanium dioxide and 0.080 g of phosphoric acid were added, and the low polymer was melt-polymerized at a temperature of 280 ° C. under a reduced pressure of 1 torr to obtain a polyethylene naphthalate copolymer having an intrinsic viscosity of 0.630 dl / g. The combined (B-4) prepolymer was produced, extruded from a nozzle into a strand, and cut to obtain a cylindrical chip having a diameter of 2.5 mm and a height of 3.5 mm.

Polyester Blend 10 parts by weight of the polyethylene naphthalate-based copolymer (B-4) was added to 90 parts by weight of the same polyethylene terephthalate (A-1) prepolymer as in Example 1. Dry blended as above, Thermo 20mmφ
Using a single-screw extruder, the mixture was melt-kneaded at a molding temperature of 285 ° C. and a residence time in the cylinder of 120 seconds, extruded from a nozzle into a strand, and cut into a cylindrical chip having a diameter of 2.5 mm and a height of 3.5 mm. The heated crystallization temperature of this prepolymer blend was 148 ° C.

Solid Phase Polymerization The chip obtained above was heated at 170 ° C. for 2 hours under a nitrogen stream.
After pre-crystallization by heating for a period of time, solid-state polymerization was further performed by heating at 210 ° C. for 16 hours.

The polyester thus obtained is
The limiting viscosity was 0.842 dl / g. Also this polyester
The carbon dioxide permeability coefficient of the stretched film obtained from 9.8 cc
mm / m ^Two・ Day ・ atm, haze value is 6.8%, naphtha
Range carboxylic acid-ethylene glycol-terephthalic acid
Of the structural units connected in the order of (L_NET) Is 8.5 mol%
The acetaldehyde content was 11 ppm.

[0113]

Example 5 Polyethylene naphthalate (B-5) 250 g of 2,6-dimethylnaphthalate, ethylene glycol 14
A slurry consisting of 2 g was prepared, 0.49 g of manganese acetate tetrahydrate was added to the slurry, and the mixture was heated to 180 ° C. under a nitrogen atmosphere at normal pressure to react until the transesterification rate reached 95%, thereby reducing the weight A coalescence was made. After adding a further 0.042 g of germanium dioxide and 0.080 g of phosphoric acid, 280 g under reduced pressure of 1 torr.
Melt polymerization of the low polymer at a temperature of
A prepolymer of polyethylene naphthalate (B-5) of 0.625 dl / g was produced, extruded in a strand shape from a nozzle and cut to obtain a cylindrical chip having a diameter of 2.5 mm and a height of 3.5 mm.

Polyester Blend The same polyethylene terephthalate (A-1) prepolymer as in Example 1 was dry-blended to 90 parts by weight of the above-mentioned polyethylene naphthalate (B-5) in an amount of 10 parts by weight. Melting and kneading at a molding temperature of 295 ° C and a residence time of 120 seconds in a cylinder using a 20 mmφ single screw extruder manufactured by Thermo Co., Ltd.
A 2.5 mm, 3.5 mm high cylindrical tip was used. The heated crystallization temperature of the prepolymer blend was 156 ° C.

Solid Phase Polymerization The chips obtained above were heated at 170 ° C. for 2 hours under a nitrogen stream.
After pre-crystallization by heating for a period of time, solid-state polymerization was further performed by heating at 210 ° C. for 16 hours.

The intrinsic viscosity of the polyester thus obtained was 0.841 dl / g. The carbon dioxide permeability coefficient of the stretched film obtained from this polyester is 14.5cc
· Mm / m ² · day · atm, the haze value is 17.8%, the amount of structural units linked in the order of naphthalenedicarboxylic acid-ethylene glycol-terephthalic acid (L _NET ) is 6.1 mol%, and acetaldehyde The content was 16 ppm.

[0117]

Comparative Example 1 The polyethylene terephthalate (A-1) prepolymer obtained in Example 1 was melt-kneaded at a molding temperature of 275 ° C. using a 20 mmφ single screw extruder manufactured by Thermo Co., Ltd., and formed into a strand from a nozzle. Extruded, cut, diameter 2.5m
m, a 3.5 mm high cylindrical tip. The pre-heating crystallization temperature of this prepolymer was 142 ° C.

Solid Phase Polymerization The chip obtained above was heated at 170 ° C. for 2 hours under a nitrogen stream.
After pre-crystallization by heating for a period of time, solid-state polymerization was further performed by heating at 210 ° C. for 16 hours.

The intrinsic viscosity of the polyester thus obtained was 0.830 dl / g. The carbon dioxide permeability coefficient of the stretched film obtained from this polyester is 16.8cc
Mm / m ² · day · atm, haze value is 7.2%, the amount of structural units linked in the order of naphthalenedicarboxylic acid-ethylene glycol-terephthalic acid (L _NET ) is 0 mol%, and acetaldehyde The content was 14 ppm.

[0120]

[Comparative Example 2] Solid phase weight of polyethylene terephthalate (A-1)
Compound purified terephthalic acid 332g and ethylene glycol 143g
Was prepared, and 0.042 g of germanium dioxide and 0.080 g of phosphoric acid were added thereto. This slurry was heated to a temperature of 255 ° C. under pressure (absolute pressure: 1.7 kg / cm ² ), and an esterification reaction was carried out until an esterification ratio became 95%, to produce a low polymer. Then, under a reduced pressure of 1 torr, 2
The above-mentioned low polymer is melt-polymerized at a temperature of 80 ° C. to produce a polyethylene terephthalate (A-1) prepolymer having an intrinsic viscosity of 0.615 dl / g, which is extruded from a nozzle into a strand, cut, and cut into diameters. A 2.5 mm, 3.5 mm high cylindrical tip was used. The pre-heating crystallization temperature of this prepolymer is 158 ° C
Met. Next, after pre-crystallizing the chip obtained above at 170 ° C. for 2 hours under a nitrogen stream, the chip was further heated to 210 ° C.
For 16 hours to perform solid phase polymerization. The intrinsic viscosity of the polyester thus obtained was 0.835 dl / g.

The polyethylene naphthalate copolymer (B-
6) 2,6-dimethylnaphthalate 228 g, dimethyl isophthalate
19 g, ethylene glycol 143 g, and average molecular weight 1000
Of 1.9 g of polytetramethylene glycol was prepared, and 0.25 g of manganese acetate tetrahydrate was charged into a reactor, and reacted while stirring at 240 ° C. for 3 hours under a nitrogen atmosphere at normal pressure. Then, set the heating temperature to 260 ° C,
Allowed to react for hours. Methanol produced by this reaction was constantly distilled out of the system. Next, 0.042 g of germanium dioxide and 0.080 g of phosphoric acid were added, and under a reduced pressure of 1 torr, 285
Melt polymerization of the low polymer at a temperature of
0.815 dl / g polyethylene naphthalate copolymer (B-6)
Was extruded from the nozzle into a strand and cut into a cylindrical chip having a diameter of 2.5 mm and a height of 3.5 mm.

[0122]Polyester blend The above polyethylene terephthalate (A-1) solid-phase polymer 90 ply
Parts by weight of the polyethylene naphthalate copolymer (B
Dry blended so that -6) becomes 10 parts by weight
Temperature using a 20 mmφ single screw extrusion molding machine manufactured by Thermo.
At a temperature of 295 ° C and a residence time of 240 seconds in the cylinder.
Extruded into a strand from the swarf and cut, 2.5 m in diameter
m, a 3.5 mm high cylindrical tip. This polyester
Was 156 ° C. In addition, the obtained po
The limiting viscosity of the ester was 0.820 dl / g. Further
In addition, carbonized stretched film obtained from this polyester
Gas permeability coefficient is 13.8cc ・ mm / m^Two・ Day ・ atm, haze value
Is 15.3%, naphthalenedicarboxylic acid-ethylene glycol
The amount of constituent units linked in the order of recall-terephthalic acid
(L _NET) Is 3.5 mol%, the acetaldehyde content
Was 19 ppm.

[0123]

Comparative Example 3 Polyethylene terephthalate (A-3) 175 g of dimethyl terephthalate, 2,6-dimethylnaphthalate
23 g, dimethyl isophthalate 2 g, ethylene glycol 143
g, and a slurry composed of 0.2 g of polytetramethylene glycol having an average molecular weight of 1000 was prepared, and 0.25 g of manganese acetate tetrahydrate was added thereto.
The reaction was performed with stirring for 3 hours. Then, set the heating temperature to 20
The reaction was carried out at 0 ° C. for 3 hours. Methanol produced by this reaction was constantly distilled out of the system.

Next, 0.042 g of germanium dioxide and
0.080 g of phosphoric acid was added, and the low polymer was melt-polymerized at a temperature of 285 ° C. under a reduced pressure of 1 torr, and the intrinsic viscosity was 0.628 dl /
g of a polyethylene terephthalate (A-3) prepolymer, which is extruded from a nozzle into a strand,
It was cut into a cylindrical chip having a diameter of 2.5 mm and a height of 3.5 mm.
The pre-heating crystallization temperature of the prepolymer was 165 ° C.

Solid Phase Polymerization The obtained chips were precrystallized by heating at 170 ° C. for 2 hours under a nitrogen stream, and then heated at 210 ° C. for 16 hours to perform solid phase polymerization.

The intrinsic viscosity of the polyester thus obtained was 0.843 dl / g. The carbon dioxide permeability coefficient of the stretched film obtained from this polyester is 14.5cc
・ Mm / m ²・ day ・ atm, the haze value is 7.1%, and the amount of structural units linked in the order of naphthalenedicarboxylic acid-ethylene glycol-terephthalic acid (L _NET ) is 16.8 mol%
And the acetaldehyde content was 13 ppm.

[0127]

[Table 1]

Claims (13)

[Claims] 1. A polyester comprising a dicarboxylic acid structural unit containing terephthalic acid and naphthalenedicarboxylic acid as a structural unit and a diol structural unit containing ethylene glycol as a structural unit, and (i) a polyester based on all dicarboxylic acid structural units. The structural unit derived from terephthalic acid is 40 to
In the range of 99.5% by weight, the structural unit derived from naphthalenedicarboxylic acid is in the range of 0.5-60% by weight, and the structural unit derived from isophthalic acid is in the range of 0-25.
(Ii) 95% of the structural units derived from ethylene glycol based on all the diol structural units.
The polyalkylene glycol structural unit having an alkylene oxide chain having 2 to 10 carbon atoms is in the range of 0 to 5% by weight, and the intrinsic viscosity is in the range of 0.5 to 1.5 dl / g. The melting point (Tm (° C)) measured by a differential scanning calorimeter is
Satisfies the following general formula [I], [1 / 527-0.0017 · ln (1- (m _I + m _N ) / 200)] ⁻¹ −273 <Tm ≦ 254… [I] (where m _I is The ratio (mol%) of the structural unit derived from isophthalic acid in all dicarboxylic acid structural units, and m _N is the ratio (mol%) of the structural unit derived from naphthalenedicarboxylic acid in all dicarboxylic acid structural units. The amount (L _NET (mol%)) of the structural unit linked in the order of naphthalenedicarboxylic acid-ethylene glycol-terephthalic acid measured by ¹ H-NMR is represented by the following general formula [II]: L _NET ≧ 0. 5 × m _N ... [II] (wherein, m _N represents a ratio (mol%) of a structural unit derived from naphthalenedicarboxylic acid in all dicarboxylic acid structural units). . 2. The melting point of the polyester (Tm (° C.))
The following general formula [I '] [1 / 527-0.0017 · ln (1- (m I + m N) / 200)] -1 -270 <Tm ≦ 254 ... [I' claims, characterized by satisfying the ' Item 10. The polyester according to Item 1. 3. The polyester according to claim 1, wherein the degree of polymerization (n) of the polyalkylene glycol is in the range of 5 to 50. 4. The method according to claim 1, wherein said polyalkylene glycol is polytetramethylene glycol.
Polyester according to any one of claims 1 to 3. 5. An injection molding temperature of 280 ° C. and a mold temperature of 10 ° C.
The polyester according to any one of claims 1 to 4, wherein the haze value of the 5 mm-thick rectangular plate obtained under the above condition is 20% or less. 6. The polyester according to claim 1, wherein the content of acetaldehyde is 20 ppm or less. 7. [A] polyethylene terephthalate before solid phase polymerization having an intrinsic viscosity of 0.3 to 0.8 dl / g; 99 to 40
% By weight, and [B] polyethylene naphthalate having an intrinsic viscosity of 0.3 to 0.7 dl / g before solid phase polymerization; 1 to 60% by weight
And then subjecting the blend to solid phase polymerization. 8. The method according to claim 1, wherein the polyethylene naphthalate [B] is (i)
A dicarboxylic acid structural unit having a naphthalenedicarboxylic acid structural unit in a range of 100 to 55% by weight and an isophthalic acid structural unit in a range of 0 to 45% by weight; (ii) an ethylene glycol structural unit of 100 to 90% by weight; The method for producing a polyester according to claim 7, wherein the polyalkylene glycol structural unit having 10 alkylene oxide chains comprises a diol structural unit in a range of 0 to 10% by weight. 9. The diol structural unit has an ethylene glycol structural unit of 99.999 to 90% by weight, and has 2 to 2 carbon atoms.
The method for producing a polyester according to claim 8, wherein the polyalkylene glycol constituent unit having 10 alkylene oxide chains is in the range of 0.001 to 10% by weight. 10. The method according to claim 8, wherein the degree of polymerization (n) of the polyalkylene glycol is in the range of 5 to 50. 11. The method according to claim 8, wherein the polyalkylene glycol is polytetramethylene glycol. 12. The method for producing a polyester according to claim 7, wherein the blend is heated and pre-crystallized, and then subjected to solid-phase polymerization. 13. The solid-state polymerization of a blend having a temperature-rise crystallization temperature of 190 ° C. or lower.
3. The method for producing a polyester according to any one of 2.