JP2010031175A - Copolyester and production method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high quality copolyester which has excellent thermal stability and is almost free from foreign matter while maintaining excellent mechanical characteristics and dimensional stability. <P>SOLUTION: The copolymer polyester includes aromatic dicarboxylic acid residues, represented by following formulas (I): -(O)C-R<SP>2</SP>-OR<SP>1</SP>O-R<SP>2</SP>-C(O)- and (II): -(O)C-R<SP>4</SP>-C(O)-, and a 2-4C alkylene glycol residue, wherein the copolymerization ratio of the aromatic dicarboxylic acid residue represented by the formula (I) is ≥5 and <50 mol% based on the total dicarboxylic acid residues, and titanium element, antimony element, and germanium element are contained in an amount of ≤15 mmol%, ≤30 mmol%, and 5-100 mmol% to the total acidic components of the copolymer polyester, respectively. In the formula (I), R<SP>1</SP>represents 2-10C alkylene group and R<SP>2</SP>represents 2, 6-naphthalenediyl group. In the formula (II), R<SP>4</SP>represents phenylene group or naphthalenediyl group. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a high-quality copolymer polyester having excellent mechanical properties and dimensional stability, excellent thermal stability, and less foreign matter.

  Aromatic polyesters typified by polyethylene terephthalate (PET) and polyethylene-2,6-naphthalenedicarboxylate (PEN) have excellent mechanical properties, dimensional stability and heat resistance, so they are widely used in films. Yes. In particular, polyethylene-2,6-naphthalenedicarboxylate has mechanical properties, dimensional stability and heat resistance superior to those of polyethylene terephthalate, and is used in demanding applications such as a base film for high-density magnetic recording media. It is used for such as. However, the demand for dimensional stability in high-density magnetic recording media and the like in recent years is increasing, and there is a demand for a film having a further reduced temperature expansion coefficient (αt) and humidity expansion coefficient (αh). .

  Under such circumstances, Patent Documents 1 to 5 mainly describe 6,6 ′-(ethylenedioxy) di-2-naphthoic acid as a higher performance polyester than polyethylene-2,6-naphthalenedicarboxylate. A polyester comprising an acid component and alkylene glycol has been proposed. However, the polyesters disclosed in these documents have a very high melting point and very high crystallinity, and when trying to form into a film or the like, the fluidity in the molten state is poor, and the extrusion becomes non-uniform, Even when trying to stretch after extrusion, there is a problem that crystallization progresses and breaks when stretched at a high magnification.

JP-A-60-135428 JP-A-60-212420 JP 61-145724 A JP-A-6-145323 International Publication No. 2008/010607 Pamphlet

  The present inventors diligently studied to provide a polyester from which a molded article such as a film having excellent mechanical properties and dimensional stability can be obtained, and used terephthalic acid or 2,6-naphthalenedicarboxylic acid as a dicarboxylic acid component. When the 6,6 '-(alkylenedioxy) di-2-naphthoic acid component is copolymerized at a specific ratio with polyester having alkylene glycol as the diol component, the humidity expansion coefficient can be reduced, and the temperature expansion coefficient is It was discovered that the Young's modulus can be increased by stretching and can be reduced.

However, according to the study of the present inventor, the polyester copolymerized with 6,6 ′-(alkylenedioxy) di-2-naphthoic acid component is titanium tetrabutoxide specifically used in the above-mentioned patent document. It was found that when the titanium catalyst is used, it tends to be thermally deteriorated when it is kept at a high temperature for a long time, and the hue tends to be yellow and inferior.
On the other hand, when an antimony catalyst is used in place of the titanium catalyst, black foreign matter is likely to be generated, and there is a problem that the surface flatness, color tone, transparency and the like of the obtained molded product are likely to deteriorate.

  The present invention has been made in the background described above, and its object is to provide a high-quality copolyester having excellent thermal stability and less foreign matters while maintaining excellent mechanical properties and dimensional stability. There is.

  As a result of repeated studies to achieve the above object, the present inventor co-polymerizes a predetermined amount of 6,6 ′-(alkylenedioxy) di-2-naphthoic acid component and also uses a predetermined amount as a polycondensation catalyst. If the germanium compound is used, a copolyester having excellent dimensional stability such as temperature expansion coefficient (αt) and humidity expansion coefficient (αh), as well as good thermal stability and few foreign matters derived from the catalyst can be obtained. Thus, the present inventors have found that such polyester is particularly suitable as a biaxially oriented film for high-density magnetic recording, and have reached the present invention.

Thus, according to the present invention, an aromatic dicarboxylic acid residue represented by the following formulas (I) and (II) and an alkylene glycol residue having 2 to 4 carbon atoms are represented by the following formula (I). A copolymerized polyester having a copolymerization ratio of aromatic dicarboxylic acid residues of 5 mol% or more and less than 50 mol% based on all dicarboxylic acid residues, and titanium, antimony and germanium are contained in the copolymerized polyester as follows: There is provided a copolyester containing the formulas (1) to (3) at a ratio satisfying at the same time.
^{- (O) C-R 2} -OR 1 O-R 2 -C (O) - (I)
— (O) C—R ⁴ —C (O) — (II)
(R ¹ in the formula (I) represents an alkylene group having 2 to 10 carbon atoms, R ² represents a 2,6-naphthalenediyl group, and R ⁴ in the formula (II) represents a phenylene group or a naphthalenediyl group. )
0 ≦ Ti ≦ 15 (1)
0 ≦ Sb ≦ 30 (2)
5 ≦ Ge ≦ 100 (3)
(In the formula, Ti, Sb and Ge are based on the total acid component of the copolyester, respectively, Ti is titanium element amount (mmol%), Sb is antimony element amount (mmol%), Ge is germanium element amount ( mmol%).)

Further, according to the present invention, the aromatic dicarboxylic acid component represented by the following formulas (III) and (IV), wherein the ratio of the aromatic dicarboxylic acid component represented by the following formula (III) is the total dicarboxylic acid An aromatic dicarboxylic acid component that is 5 mol% or more and less than 50 mol% based on the component and an alkylene glycol having 2 to 4 carbon atoms are transesterified using a titanium compound or a manganese compound as a catalyst, and then a germanium compound There is also provided a process for producing the above-mentioned copolymerized polyester, characterized in that a polycondensation reaction is carried out using as a catalyst.
R ³ O (O) C—R ² —OR ¹ O—R ² —C (O) OR ³ (III)
R ⁵ O (O) C—R ⁴ —C (O) OR ⁵ (IV)
(In formula (III), R ¹ represents an alkylene group having 2 to 10 carbon atoms, R ² represents a 2,6-naphthalenediyl group, R ³ represents an alkyl group having 1 to 4 carbon atoms, and in formula (IV), R ⁴ represents a phenylene group or a naphthalenediyl group, and R ⁵ represents an alkyl group having 1 to 4 carbon atoms.)

  The biaxially oriented film obtained using the copolymerized polyester of the present invention has a low temperature expansion coefficient (αt) and humidity expansion coefficient (αh), and has excellent dimensional stability against environmental changes such as temperature and humidity. In addition, since there are few foreign substances derived from the catalyst, it is excellent in surface flatness and transparency, and also excellent in thermal stability, and can be suitably used in various fields where these characteristics are required. It can be suitably used as a base film for magnetic recording media or an optical film.

[Copolyester]
The copolymer polyester of the present invention is composed of an aromatic dicarboxylic acid residue described below and an alkylene glycol residue having 2 to 4 carbon atoms.
The aromatic dicarboxylic acid residue of the copolymer polyester of the present invention is represented by the above formula (I) in an amount of 5 mol% or more and less than 50 mol%, and more than 50 mol% and 95 mol% or less is represented by the above formula (II). It is what is done.

In Formula (I), R ¹ is an alkylene group having 2 to 10 carbon atoms, and examples thereof include an ethylene group, a trimethylene group, a tetramethylene group, a hexamethylene group, and an octamethylene group. Such aromatic dicarboxylic acid residues include 6,6 ′-(ethylenedioxy) di-2-naphthoic acid, 6,6 ′-(trimethylenedioxy) di-2-naphthoic acid and 6,6′-. A dicarboxylic acid residue derived from (tetramethylenedioxy) di-2-naphthoic acid is preferable, and an even number of carbon atoms of R ¹ is particularly preferable, and 6,6 ′-(ethylenedioxy) di-2- is particularly preferable. A dicarboxylic acid residue derived from naphthoic acid is preferable because a biaxially oriented film excellent in humidity expansion coefficient can be easily obtained while maintaining mechanical properties.

  The ratio of the aromatic dicarboxylic acid residue represented by the formula (I) is 50 mol% (excluding 50 mol%), preferably 45 mol%, based on the total aromatic dicarboxylic acid residue, More preferably, it is 40 mol%, More preferably, it is 35 mol%, Most preferably, it is 30 mol%. On the other hand, the lower limit is 5 mol%, preferably 7 mol%, more preferably 10 mol%, particularly preferably 15 mol%. Therefore, the ratio of the dicarboxylic acid residue represented by the formula (I) needs to be 5 mol% or more and less than 50 mol%, preferably 5 to 45 mol%, more preferably 7 to 40 mol%, More preferably, it is 10-35 mol%, Most preferably, it is the range of 15-30 mol%.

  The copolymer polyester in the present invention is characterized in that a ratio of 5 mol% or more and less than 50 mol% of the aromatic dicarboxylic acid residue is a residue represented by the formula (I). When the proportion of the unit represented by the formula (I) is less than the lower limit, the effect of reducing the humidity expansion coefficient (αh) due to the copolymerization of the dicarboxylic acid residue is hardly exhibited. On the other hand, by making the amount lower than the upper limit, there are advantages that the film-forming property at the time of forming into a film is excellent and the temperature expansion coefficient (αt) can be easily reduced. The effect of reducing the humidity expansion coefficient (αh) by the residue represented by the formula (I) is expressed very efficiently even in a small amount. Therefore, by using the copolymer polyester of the present invention, the temperature expansion coefficient (αt ) And a humidity expansion coefficient (αh) are both low, and a molded article such as a biaxially oriented film can be produced.

On the other hand, in the aromatic dicarboxylic acid residue represented by the formula (II), R ² is a phenylene group or a naphthalenediyl group, for example, terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2 , 7-naphthalenedicarboxylic acid and other aromatic dicarboxylic acid residues. Of these, acid residues derived from terephthalic acid or 2,6-naphthalenedicarboxylic acid are preferable, and acid residues derived from 2,6-naphthalenedicarboxylic acid are particularly preferable. In addition, even if these are only 1 type, 2 or more types may be combined.

The alkylene glycol residue is represented by —OC _n H _2n O— (n is an integer of 2 to 4) and is a residue derived from ethylene glycol, trimethylene glycol or tetramethylene glycol. Among these, ethylene glycol is preferable because of excellent mechanical properties of a molded article such as a film.

  The copolymer polyester comprising the aromatic dicarboxylic acid residue and the alkylene glycol residue is 35 using a mixed solvent of P-chlorophenol / 1,1,2,2-tetrachloroethane (weight ratio 40/60). The intrinsic viscosity measured at ° C is preferably in the range of 0.4 to 3 dl / g, more preferably in the range of 0.4 to 1.5 dl / g, and particularly preferably in the range of 0.5 to 1.2 dl / g.

  The melting point measured by DSC is preferably in the range of 200 to 260 ° C, more preferably 210 to 255 ° C, particularly preferably 220 to 253 ° C. When this melting point exceeds the upper limit, when melt extrusion is performed, it is necessary to make the temperature higher in order to increase fluidity, and thermal degradation is likely to occur. On the other hand, when the melting point is lower than the lower limit, the film forming property is excellent. However, the mechanical properties of polyester are easily impaired.

  Furthermore, the glass transition temperature (Tg) measured by DSC is preferably 80 to 125 ° C, more preferably 95 to 123 ° C, and particularly preferably 110 to 120 ° C. When Tg is in this range, a molded article such as a film having excellent heat resistance and dimensional stability can be obtained. The melting point and glass transition temperature can be easily adjusted by controlling the type of copolymerization component and the copolymerization ratio.

  In the copolymerized polyester according to the present invention, other copolymer components known per se, for example, 10 mol% or less, particularly 5 mol% or less, based on the total acid component, within a range not impairing the effects of the present invention. It may be further copolymerized in the range of.

The copolyester of the present invention has the second feature that the amount of titanium element, the amount of antimony element, and the amount of germanium element satisfy the following formulas (1) to (3).
0 ≦ Ti ≦ 15 (1)
0 ≦ Sb ≦ 30 (2)
5 ≦ Ge ≦ 100 (3)
(In the formula, Ti, Sb and Ge are based on the total acid component of the copolyester, respectively, Ti is titanium element amount (mmol%), Sb is antimony element amount (mmol%), Ge is germanium element amount ( mmol%).)

  First, the amount of titanium element needs to satisfy the formula (1) in order to improve the thermal stability and hue of the copolyester, preferably 10 mmol% or less, and particularly preferably does not contain a titanium element. That is. By doing so, it is possible to suppress thermal deterioration of the copolymerized polyester due to the titanium element and yellowing of the hue. Therefore, in the production of the copolyester described later, when producing a polyester precursor by an esterification reaction or producing a polyester precursor by an ester exchange reaction, the titanium compound as a transesterification reaction catalyst should be reduced as much as possible. Is important.

  Further, the amount of antimony element needs to satisfy the formula (2) in order to suppress the formation of foreign matter in the copolyester, preferably 16 mmol% or less, and particularly preferably no antimony element. . By doing so, the generation of black foreign matters due to the reduction reaction of the antimony element is suppressed, the color tone and transparency are improved, and the surface flatness of the obtained molded product is also improved. Therefore, in the production of a copolyester described later, it is important to reduce the amount of antimony compound as much as possible as a catalyst for polycondensation of a polyester precursor produced by an esterification reaction or a transesterification reaction.

  Further, the amount of germanium element needs to satisfy the formula (3) in order to act as a catalyst for the polycondensation reaction of the copolyester, preferably 10 to 80 mmol%, particularly preferably 15 to 60 mmol%. It is a range. When the amount of germanium element is less than 5 mmol%, the polycondensation reaction does not proceed sufficiently, which is not preferable. On the other hand, when it exceeds 100 mmol%, the hue of the resulting polyester is deteriorated or the thermal stability is lowered, which is not preferable.

  In the copolyester of the present invention, other thermoplastic polymers, ultraviolet absorbers, antioxidants, plasticizers, lubricants, flame retardants, release agents, pigments, nucleating agents, as long as the effects of the present invention are not impaired. Fillers or glass fibers, carbon fibers, layered silicates and the like may be blended as necessary, and this is preferable because it makes it easy to impart further characteristics to the film obtained. Examples of other thermoplastic polymers include polyamide resins, polycarbonates, ABS resins, polymethyl methacrylate, polyamide elastomers, polyester elastomers, and 6,6 ′-(alkylenedioxy) di-2-naphthoic acid. Examples thereof include polyester resins not included.

[Method for producing copolymer polyester]
The copolyester of the present invention described above can be produced according to a conventionally known polyester production method. Hereinafter, a preferable method will be described by taking the case where the alkylene glycol is ethylene glycol as an example, but other alkylene glycols can be produced by the same method. That is, a lower alkyl ester of 6,6 ′-(alkylenedioxy) di-2-naphthoic acid represented by the following formula (III) or a corresponding dicarboxylic acid and the following formula (IV), for example, 2 First, a polyester precursor is produced by transesterification or ester reaction of ethylene glycol with a lower alkyl ester of 1,6-naphthalenedicarboxylic acid or terephthalic acid or the corresponding dicarboxylic acid and ethylene glycol. Then, the obtained polyester precursor can be produced by polycondensation in the presence of a polycondensation reaction catalyst, and solid-phase polymerization as required. Especially, the method of manufacturing a polyester precursor first by a transesterification method is more preferable.
R ³ O (O) C—R ² —OR ¹ O—R ² —C (O) OR ³ (III)
R ⁵ O (O) C—R ⁴ —C (O) OR ⁵ (IV)
(In formula (III), R ¹ represents an alkylene group having 2 to 10 carbon atoms, R ² represents a 2,6-naphthalenediyl group, R ³ represents an alkyl group having 1 to 4 carbon atoms, and in formula (IV), R ⁴ represents a phenylene group or a naphthalenediyl group, and R ⁵ represents an alkyl group having 1 to 4 carbon atoms.)

  Two types of polyesters having different ratios of the aromatic dicarboxylic acid residues represented by the aforementioned formulas (I) and (II) are prepared, and the ratios of the aforementioned formulas (I) and (II) are intended. They may be melt kneaded. In this case, one polyester does not need to contain the aromatic dicarboxylic acid residue represented by the formula (I).

  In the process for producing the polyester precursor, ethylene glycol is used in an amount of 1.1 to 10 times, more preferably 1.5 to 5 times, especially 2 to 5 times the number of moles of the total acid component. From the viewpoint of sex.

  Moreover, as reaction temperature at the time of manufacturing a polyester precursor, it is preferable to carry out above the boiling point of ethylene glycol, and it is preferable to carry out especially in the range of 190-250 degreeC. When the temperature is lower than 190 ° C., the reaction does not proceed sufficiently. When the temperature is higher than 250 ° C., diethylene glycol as a side reaction product is likely to be generated. In addition, the reaction can be performed under normal pressure, but may be performed under pressure to further increase productivity.

  In the step of producing this polyester precursor, a known esterification or transesterification reaction catalyst may be used. However, when a titanium compound is used, the amount of titanium element is such that it satisfies the above formula (1). It is necessary to use for. When the amount of elemental titanium exceeds 15 mmol%, the thermal stability of the resulting copolymerized polyester is significantly reduced. In addition, when not using a catalyst other than a titanium compound as a transesterification reaction catalyst, it is preferable to use it in the ratio from which a titanium element amount will be 3 mmol% or more, and when less than 3 mmol%, reaction activity becomes inadequate. Examples of suitable catalysts other than titanium compounds include manganese compounds, zinc compounds, magnesium compounds, calcium compounds, and the like. In particular, manganese compounds are less likely to produce foreign matter in the resulting polyester and have excellent surface flatness and transparency. It is preferable because a molded product such as a film can be obtained. In addition, if the content of the manganese element is small, the transesterification reaction activity becomes insufficient. Conversely, if the content is too large, the thermal stability may be lowered. Therefore, 10-80 mmol with respect to the total acid component of the copolyester. A range of% is suitable.

  In addition, in order to improve the thermal stability and hue of the resulting copolyester, a phosphorus compound was added as a stabilizer at the stage where the reaction for producing the polyester precursor was completed, and it was used in the esterification reaction or transesterification reaction. The catalyst is preferably deactivated. As a phosphorus compound used here, a well-known thing can be used as a stabilizer of polyester polymerization, for example, phosphoric acid, phosphorous acid, phosphoric acid trimethyl ester, a triethylphosphonoacetate etc. can be illustrated.

  Next, the polycondensation temperature is in the range of a temperature not lower than the melting point of the obtained copolyester and not higher than 230 to 280 ° C., more preferably not lower than 5 ° C. and higher than the melting point by 30 ° C. The polycondensation reaction is usually preferably performed under a reduced pressure of 50 Pa or less. If it is higher than 50 Pa, the time required for the polycondensation reaction becomes long and it becomes difficult to obtain a copolymer polyester having a high degree of polymerization.

  As the polycondensation catalyst, it is important to use a germanium compound in a ratio satisfying the above-described formula (3) in order to obtain a copolyester having excellent thermal stability and few foreign substances and good transparency. However, other polymerization catalysts may be contained within a range that does not impair the object of the present invention. In the case of a titanium compound as described above, it is within the range satisfying the above formula (1), and the antimony compound In such a case, it is within the range satisfying the formula (2).

  In order to suppress by-production of diethylene glycol during the production of the copolyester, hydroxides, acetates, carbonates and the like of potassium compounds and sodium compounds may be further added.

[Molding of copolyester]
The copolymerized polyester of the present invention can be made into a molded product such as a bottle or a container by melt spinning and forming into a fiber, melt forming into a film or sheet, and injection molding. In particular, when a biaxially oriented film is used, it has excellent mechanical properties and dimensional stability as described above, and also has excellent thermal stability and less flatness, and has excellent flatness. In particular, it is a base film for magnetic recording media. It is suitable as.

[Method for producing biaxially oriented polyester film]
In order to produce a biaxially oriented polyester film, for example, the copolymer polyester is dried and then supplied to an extruder heated to a melting point (Tm: ° C.) to (Tm + 50) ° C. of the copolymer polyester and melted. For example, it is extruded into a sheet shape from a die such as a T die, and the extruded sheet material is rapidly cooled and solidified by a rotating cooling drum or the like to obtain an unstretched film.

  At that time, in order to facilitate the subsequent stretching, it is preferable to perform cooling with a cooling drum very quickly, and it is preferable to perform the cooling at a low temperature of 20 to 60 ° C. By performing at such a low temperature, crystallization in the state of an unstretched film is suppressed, and subsequent stretching can be performed more smoothly.

The unstretched film thus obtained is biaxially stretched. Biaxial stretching may be sequential biaxial stretching or simultaneous biaxial stretching. Here, a manufacturing method in which longitudinal stretching, lateral stretching, and heat treatment are performed in this order by sequential biaxial stretching will be described as an example. First, the first longitudinal stretching is performed at a glass transition temperature (Tg: ° C.) to (Tg + 40) ° C. of the copolyester, which is stretched 3 to 10 times, preferably 4 to 8 times. The film is stretched 3 to 11 times, more preferably 5 to 10 times at a temperature of (Tg + 10) to (Tg + 50) ° C. at a higher temperature than the longitudinal stretching, and further at a temperature below the melting point of the polymer as a heat treatment and (Tg + 50) to (Tg + 150). ) Heat setting at a temperature of 1 ° C. for 1 to 20 seconds, preferably 1 to 15 seconds.
In the case of simultaneous biaxial stretching in which longitudinal stretching and lateral stretching are simultaneously performed, the above-described sequential biaxial stretching stretching ratio and stretching temperature may be referred to.

  In addition, the film forming direction (longitudinal direction) of the film is Machine Direction (MD), and the width direction (lateral direction) of the film is a direction orthogonal to the film forming direction (MD) of the film, and is referred to as a Transverse Direction (TD) direction. .

[Biaxially oriented polyester film]
In the biaxially oriented polyester film thus obtained, the temperature expansion coefficient (αt) in the width direction of the film is preferably 14 × 10 ⁻⁶ / ° C. or less, more preferably 10 × 10 ⁻⁶ / ° C. or less, and further A range of preferably 7 × 10 ⁻⁶ ° C. or less, particularly preferably 5 × 10 ⁻⁶ / ° C. or less is preferable because it can exhibit excellent dimensional stability against dimensional changes due to changes in the temperature of the atmosphere. On the other hand, the lower limit of the temperature expansion coefficient (αt) in the width direction is preferably −15 × 10 ⁻⁶ / ° C., more preferably −10 × 10 ⁻⁶ / ° C., and further preferably −7 × 10 ⁻⁶ / ° C. . When the temperature expansion coefficient in the width direction of the film is in the above range, it becomes easy to suppress a dimensional change when the magnetic tape is formed.

Moreover, the humidity expansion coefficient (αh) in the width direction of the film is in the range of 1 × 10 ^{−6 to} 7 × 10 ⁻⁶ /% RH, and further 1 × 10 ^{−6 to} 6 × 10 ⁻⁶ /% RH. preferable. When αh is in this range, the dimensional stability is improved when the magnetic recording tape is formed.

  Furthermore, the Young's modulus in the film forming direction of the film is preferably 4.5 GPa or more, more preferably 5 GPa or more from the viewpoint of suppressing elongation during high-temperature processing. The upper limit of the Young's modulus (Y) in the film forming direction of the film is preferably about 12 GPa because it is easy to provide a sufficient Young's modulus in the width direction of the film. On the other hand, since the Young's modulus in the width direction of the film is in the range of 6 to 14 GPa, more preferably in the range of 7 to 12 GPa, it is easy to adjust the temperature expansion coefficient and humidity expansion coefficient in the width direction of the film within the above ranges. preferable.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. In the present invention, the characteristics were measured and evaluated by the following methods. In the examples, ppm and parts are values based on weight unless otherwise specified.

(1) Intrinsic viscosity (IV)
The intrinsic viscosity of the obtained polyester was determined by measuring in a 35 ° C. atmosphere using a mixed solvent of p-chlorophenol / 1,1,2,2-tetrachloroethane (40/60 weight ratio).

(2) Thermal degradation (ΔIV)
After 100 g of the obtained polyester is dried at 180 ° C. for 5 hours, the polyester is melted at a melting temperature of 320 ° C. in an air atmosphere, and held in a molten state for 30 minutes after melting. Thereafter, the molten polyester is taken out and rapidly cooled and solidified to obtain a melt-treated sample. About this melt-processed sample and the unprocessed sample before melt-processing, both intrinsic viscosities are measured and let the difference be the index (DELTA) IV of the thermal stability at the time of fusion. The smaller ΔIV is, the smaller the decrease in molecular weight due to the decomposition reaction during the melting process, and the better the thermal stability.

(3) Content of coarse foreign matter The obtained polyester was heated to 200 ° C. with tetraethylene glycol to be decomposed and dissolved to obtain a solution, and the solution was filtered through a straight membrane filter having a pore diameter of 8 μm. Then, the number of insoluble coarse particles remaining on the filter was counted, and the content was calculated as pieces / mg based on the weight of the dissolved polyester.

(4) Copolymerization amount (glycol component) 10 mg of a sample was dissolved in 0.5 ml of a mixed solution of p-chlorophenol: 1,1,2,2-deuterated tetrachloroethane = 3: 1 (volume ratio) at 80 ° C. and isopropyl After adding amine and mixing well, ¹ H-NMR of 600 MHz was measured at 80 ° C. using JEOL A600 manufactured by JEOL Ltd., and the amount of each glycol component was determined.
(Acid component) 60 mg of a sample was dissolved at 140 ° C. in 0.5 ml of a mixed solution of p-chlorophenol: 1,1,2,2-deuterated tetrachloroethane = 3: 1 (volume ratio), and ¹³ C-NMR at 150 MHz was analyzed. It measured at 140 degreeC using JEOL Co., Ltd. make and JEOL A600, and calculated | required each acid component amount.

(5) Temperature expansion coefficient (αt)
The obtained polyester is formed into a film, cut into a width of 4 mm so that the width direction (TD direction) of the film becomes the measurement direction, and set to Seiko Instruments Inc., trade name TMA / SS6000 with a measurement length of 20 mm. In a nitrogen atmosphere (0% RH), pretreatment was performed at 80 ° C. for 30 minutes, and then the temperature was lowered to room temperature. Thereafter, the temperature was raised from 30 ° C. to 80 ° C. at 2 ° C./min, the sample length at each temperature was measured, and the temperature expansion coefficient (αt) was calculated from the following equation. In addition, the measurement direction is the longitudinal direction of the sample cut out, the measurement was performed 5 times, and the average value was used.
αt = {(L ⁶⁰ −L ⁴⁰ )} / (L ⁴⁰ × ΔT)} + 0.5 × 10 ⁻⁶
Here, L ⁴⁰ in the above formula is the sample length (mm) at 40 ° C., L ⁶⁰ is the sample length (mm) at 60 ° C., ΔT is 20 (= 60-40) ° C., 0.5 × 10 ⁻⁶ (/ ° C.) is a coefficient of thermal expansion (αt) of quartz glass.

(6) Humidity expansion coefficient (αh)
The obtained polyester is formed into a film, cut into a width of 5 mm so that the width direction (TD direction) of the film becomes the measurement direction, and set in a trade name TMA4000SA made by Bruker AXS Co., Ltd. with a measurement length of 15 mm. In a nitrogen atmosphere at 30 ° C., the length of each sample at a humidity of 20% RH and a humidity of 80% RH was measured, and a humidity expansion coefficient (αh) was calculated by the following equation. In addition, the measurement direction is the longitudinal direction of the cut out sample, the measurement was performed 5 times, and the average value was αh.
αh = (L ⁸⁰ −L ²⁰ ) / (L ²⁰ × ΔH)
Here, L ²⁰ in the above formula is a sample length (mm) when 20% RH, L ⁸⁰ is a sample length (mm) when 80% RH, ΔH: 60 (= 80-20)% RH is there.

[Example 1]
6,6 ′-(ethylenedioxy) di-2-naphthoic acid dimethyl 10 kg (23.2 mol), 2,6-naphthalenedicarboxylic acid dimethyl ester 21.3 kg (87.2 mol), ethylene glycol 27.5 kg The mixture was charged into a pressure vessel equipped with a stirrer, a rectifying column, and a cooling tube, and the temperature was raised to 150 ° C. At that time, as a transesterification reaction catalyst, 6.6 g of a reaction product obtained by reacting titanium tetrabutoxide and trimellitic anhydride at a molar ratio of 1: 2 at 175 ° C. for 4 hours was added. The transesterification reaction was carried out by controlling the pressure to 20 MPa and further heating. When the column top temperature of the rectifying column reached 180 ° C., the total reflux was performed, and the reaction was continued at a reflux ratio of 1 at 180 ° C. or lower. When the reaction solution temperature reached 205 ° C., dimethyl 6,6 ′-(ethylenedioxy) di-2-naphthoate was dissolved in ethylene glycol and became transparent. The reaction was terminated when the internal temperature was finally raised to 245 ° C.

Subsequently, when the pressure was returned to normal pressure, the internal temperature decreased to 220 ° C., but no precipitate was observed. Thereafter, 9.9 g of triethylphosphonoacetate as a stabilizer and 3.5 g of amorphous germanium dioxide as a polycondensation reaction catalyst were added, the internal temperature was raised again to 250 ° C., and excess ethylene glycol was distilled off. The reaction solution was transferred to a polycondensation vessel.
Thereafter, while gradually raising the temperature inside the reaction vessel, the inside of the vessel was slowly depressurized and the polycondensation reaction was continued until a predetermined stirring power was reached at 290 ° C. and 50 Pa to produce a copolyester.

  The obtained copolyester was dried at 180 ° C. for 5 hours, then supplied to an extruder and sheeted on a cooling drum at a temperature of 55 ° C. while rotating in a molten state from a die at 295 ° C. (average residence time: 20 minutes). Extruded into an unstretched film. Then, between two sets of rollers having different rotational speeds along the film forming direction, the film surface temperature is heated from above by an IR heater so that the film surface temperature becomes 133 ° C., and stretching in the longitudinal direction (film forming direction) is performed. A uniaxially stretched film was obtained at a magnification of 5.0. And this uniaxially stretched film is led to a stenter, a transverse stretching temperature of 135 ° C., a transverse stretching ratio of 8.3 times, heat setting treatment (202 ° C. for 10 seconds) and cooling, and a biaxially stretched film having a thickness of 5.0 μm. Got. The properties of the obtained copolymer polyester and biaxially oriented polyester film are shown in Table 1.

[Example 2]
In Example 1, the amount of dimethyl 6,6 ′-(ethylenedioxy) di-2-naphthoate was 17 kg (39.5 mol), and the amount of 2,6-naphthalenedicarboxylic acid dimethyl ester was 17.9 kg (73 3 mol), and the amount of ethylene glycol was changed to 28 kg, the same operation as in Example 1 was carried out to produce a copolyester.

  The obtained copolyester was dried at 180 ° C. for 5 hours, then supplied to an extruder and sheet-shaped on a cooling drum at a temperature of 55 ° C. while rotating in a molten state from a die at 300 ° C. (average residence time: 20 minutes). Extruded into an unstretched film. Then, between the two sets of rollers having different rotational speeds along the film forming direction, the film surface temperature is heated from above by an IR heater so that the film surface temperature becomes 125 ° C., and stretching in the longitudinal direction (film forming direction) is performed. A uniaxially stretched film was obtained at a magnification of 6.2. And this uniaxially stretched film is led to a stenter, a transverse stretch temperature of 125 ° C., a transverse stretch ratio of 9.5 times, heat setting treatment (190 ° C. for 10 seconds) and cooling, and a biaxially stretched film having a thickness of 4.5 μm Got. The properties of the obtained copolymer polyester and biaxially oriented polyester film are shown in Table 1.

[Example 3]
In Example 1, the same operation as in Example 1 was performed except that the transesterification catalyst was 9.5 g of manganese acetate and the amount of the stabilizer triethylphosphonoacetate was 12.4 g. The properties of the obtained copolymer polyester and biaxially oriented polyester film are shown in Table 1.

[Example 4]
In Example 1, the same operation as in Example 1 was performed except that the polycondensation reaction catalyst was changed to 2.9 g of amorphous germanium dioxide and 2.6 g of antimony trioxide. The properties of the obtained copolymer polyester and biaxially oriented polyester film are shown in Table 1.

[Comparative Example 1]
In Example 1, 13.2 g of a reaction product obtained by reacting titanium tetrabutoxide and trimellitic anhydride at a molar ratio of 1: 2 at 175 ° C. for 4 hours as a transesterification catalyst / polycondensation reaction catalyst was added, and a germanium compound was added. Was added, and the same operation as in Example 1 was performed except that 5 g of triethylphosphonoacetate was added as a stabilizer. The properties of the obtained copolymer polyester and biaxially oriented polyester film are shown in Table 1.

[Comparative Example 2]
In Example 1, the same operation as in Example 1 was performed except that the polycondensation reaction catalyst was changed to 12.9 g of antimony trioxide. The properties of the obtained copolymer polyester and biaxially oriented polyester film are shown in Table 1.

[Comparative Example 3]
In Example 1, the same operation as in Example 1 was performed except that the amount of amorphous germanium dioxide was changed to 13.9 g. The properties of the obtained copolymer polyester and biaxially oriented polyester film are shown in Table 1.

[Comparative Example 4]
In Example 1, the same operation as in Example 1 was performed except that the amount of amorphous germanium dioxide was changed to 0.3 g. However, the polycondensation reaction did not proceed and only an IV copolyester was obtained. It was. The polyester was difficult to form into a film. The properties of the obtained copolyester are shown in Table 1.

  In Table 1, B component is 2,6-naphthalenedicarboxylic acid component, A component is 6,6 '-(ethylenedioxy) di-2-naphthoic acid component, TMT is titanium tetrabutoxide and trimellitic anhydride. A reaction product reacted at a molar ratio of 1: 2 at 175 ° C. for 4 hours, Mn represents manganese acetate, Ge represents amorphous germanium dioxide, Sb represents antimony trioxide, and P represents triethylphosphonoacetate. Each amount of the transesterification reaction catalyst and polycondensation reaction catalyst is the amount of metal element (mmol%) of each compound added as a catalyst based on the number of moles of all acid components of the polyester, and the amount of stabilizer is the total amount. The phosphorus element amount (mmol%) of the phosphorus compound added to deactivate the catalyst based on the number of moles of the acid component is shown. Moreover, TD shows the width direction of a biaxially oriented polyester film.

  The copolymerized polyester of the present invention can be subjected to ordinary melt molding such as extrusion molding, injection molding, compression molding, blow molding, and is excellent in mechanical properties, thermal stability and dimensional stability, fiber, film, It can be molded into three-dimensional molded products, containers, hoses and the like. In particular, when a biaxially oriented film is used, it has excellent surface flatness and transparency because it has few foreign matters, and can be suitably used as a base film for magnetic recording media, for example.

Claims (5)

An aromatic dicarboxylic acid residue represented by the following formulas (I) and (II) and an alkylene glycol residue having 2 to 4 carbon atoms, A copolymerized polyester having a copolymerization ratio of 5 mol% or more and less than 50 mol% based on the total dicarboxylic acid residues, wherein titanium element, antimony element and germanium element are represented by the following formula (1) -(3) is contained in the ratio which satisfies simultaneously, Copolyester characterized by the above-mentioned.
^{- (O) C-R 2} -OR 1 O-R 2 -C (O) - (I)
— (O) C—R ⁴ —C (O) — (II)
(R ¹ in the formula (I) represents an alkylene group having 2 to 10 carbon atoms, R ² represents a 2,6-naphthalenediyl group, and R ⁴ in the formula (II) represents a phenylene group or a naphthalenediyl group. )
0 ≦ Ti ≦ 15 (1)
0 ≦ Sb ≦ 30 (2)
5 ≦ Ge ≦ 100 (3)
(In the formula, Ti, Sb and Ge are based on the total acid component of the copolyester, respectively, Ti is titanium element amount (mmol%), Sb is antimony element amount (mmol%), Ge is germanium element amount ( mmol%).)   The copolyester according to claim 1, wherein the aromatic dicarboxylic acid residue represented by the formula (I) is a 6,6 '-(ethylenedioxy) di-2-naphthoic acid residue.   The copolymer polyester according to claim 1 or 2, wherein the aromatic dicarboxylic acid residue represented by the formula (II) is a 2,6-naphthalenedicarboxylic acid residue. An aromatic dicarboxylic acid component represented by the following formulas (III) and (IV), wherein the proportion of the aromatic dicarboxylic acid component represented by the following formula (III) is 5 mol% or more based on the total dicarboxylic acid component An aromatic dicarboxylic acid component of less than 50 mol% and an alkylene glycol having 2 to 4 carbon atoms are transesterified using a titanium compound or a manganese compound as a catalyst, and then a polycondensation reaction using a germanium compound as a catalyst The method for producing a copolyester according to claim 1, wherein:
R ³ O (O) C—R ² —OR ¹ O—R ² —C (O) OR ³ (III)
R ⁵ O (O) C—R ⁴ —C (O) OR ⁵ (IV)
(In formula (III), R ¹ represents an alkylene group having 2 to 10 carbon atoms, R ² represents a 2,6-naphthalenediyl group, R ³ represents an alkyl group having 1 to 4 carbon atoms, and in formula (IV), R ⁴ represents a phenylene group or a naphthalenediyl group, and R ⁵ represents an alkyl group having 1 to 4 carbon atoms.)   The method for producing a copolyester according to claim 4, wherein the germanium compound is amorphous germanium dioxide.