JP2008189800A - Copolymerized polyethylene-2,6-naphthalate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a copolyester capable of giving a formed product of excellent in orientation processability and dimensional stability, while maintaining excellent properties inherent in polyethylene-2,6-naphthalate. <P>SOLUTION: The copolyester is a copolymerized polyethylene-2,6-naphthalate composed of an aromatic dicarboxylic acid component and an alkylene glycol component, wherein 50 mol% or more and less than 95 mol% of the aromatic dicarboxylic acid component is a naphthalanedicarboxylic acid component and 5 mol% or more but less than 50 mol% of the aromatic dicarboxylic acid component is 6,6'-(alkylenedioxy)di-2-naphthoic acid. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to polyethylene-2,6-naphthalate copolymerized with 6,6 '-(ethylenedioxy) di-2-naphthoic acid.

  Polyethylene-2,6-naphthalate has better mechanical properties, dimensional stability and heat resistance than polyethylene terephthalate, so it is used in demanding applications such as base films for high-density magnetic recording media. Has been. However, the demand for dimensional stability in high-density magnetic recording media and the like in recent years is increasing, and further improvement of characteristics is required.

  By the way, as a polyester having higher performance than polyethylene naphthalate, Patent Documents 1 to 4 disclose diethyl 6,6 ′-(ethylene, which is an ester compound of 6,6 ′-(ethylenedioxy) di-2-naphthoic acid. Aromatic polyester resins obtained from dioxy) di-2-naphthoate have been proposed. According to these publications, crystalline 6,6 '-(ethylenedioxy) di-2-naphthalate, which is crystalline and has a melting point of 294 ° C., is specifically presented.

  However, since polyethylene 6,6 ′-(ethylenedioxy) di-2-naphthalate presented in these patent documents has a very high melting point and very high crystallinity, it is attempted to form a film or the like. However, since the fluidity in the molten state is poor, there is a problem that the extrusion becomes non-uniform, and even if trying to stretch after extrusion, crystallization progresses and the film tends to break when stretched at a high magnification.

JP-A-60-135428 JP-A-60-212420 JP 61-145724 A JP-A-6-145323

  An object of the present invention is to provide a copolymerized polyethylene-2,6-naphthalate capable of providing a molded article having excellent stretchability and dimensional stability while maintaining the excellent properties of polyethylene-2,6-naphthalate. Is to provide.

  As a result of diligent research to solve the above-mentioned problems, the present inventor has copolymerized polyethylene-2,6-naphthalate with 6,6 ′-(ethylenedioxy) di-2-naphthoic acid within a specific range. , Polyethylene-2,6-naphthalate copolymer polyethylene-2, which maintains the mechanical properties, heat resistance, moldability and the like, is excellent in stretchability, and has a very low dimensional stability, particularly humidity expansion coefficient. The inventors have found that 6-naphthalate can be obtained and reached the present invention.

（Ｒは炭素数２から１０のアルキレン基）
で表される６，６’−（アルキレンジオキシ）ジ−２−ナフトエ酸成分であり、グリコール成分の９０モル％以上がエチレングリコール残基であって、かつ固有粘度が０．４〜３．０であることを特徴とする共重合ポリエチレン−２，６−ナフタレート、およびそれを用いたフィルムが提供される。 Thus, according to the present invention, it is composed of an aromatic dicarboxylic acid component and an alkylene glycol component, and 50 mol% or more and less than 95 mol% of the aromatic dicarboxylic acid component is a naphthalenedicarboxylic acid component, and 5 mol% of the aromatic dicarboxylic acid component. More than less than 50 mol% is the following formula (1)

(R is an alkylene group having 2 to 10 carbon atoms)
And 6 '-(alkylenedioxy) di-2-naphthoic acid component, wherein 90 mol% or more of the glycol component is an ethylene glycol residue, and the intrinsic viscosity is 0.4-3. Copolymer polyethylene-2,6-naphthalate characterized by being zero, and a film using the same are provided.

  As a preferred embodiment of the present invention, the melting point is preferably in the range of 195 to 260 ° C. Furthermore, it is preferable that copolymer polyethylene-2,6-naphthalate does not exhibit liquid crystallinity. That is, it is preferable that no peak is observed in the range of 2θ of 5 to 10 ° in the XRD measurement of the amorphous material obtained by melting once at 340 ° C. and then rapidly cooling in an ice bath. In DSC measurement, it is preferable that only one endothermic peak is observed in the range of 120 ° C. to 220 ° C. when the temperature is raised to 320 ° C. at a temperature raising rate of 20 ° C./min and then cooled at 10 ° C./min.

  According to the present invention, while maintaining the mechanical properties, heat resistance, moldability, and other properties of polyethylene-2,6-naphthalate, the humidity expansion coefficient can be very low, and dimensional stability can be dramatically improved. can do.

（Ｒは炭素数２から１０のアルキレン基）
で表される６，６’−（アルキレンジオキシ）ジ−２−ナフトエ酸成分であり、グリコール成分の９０モル％以上がエチレングリコール残基であることを特徴とする。 The copolymerized aromatic polyethylene-2,6-naphthalate of the present invention comprises an aromatic dicarboxylic acid component and an alkylene glycol component, and 50 mol% or more and less than 95 mol% of the aromatic dicarboxylic acid component is a naphthalenedicarboxylic acid component, 5 mol% or more and less than 50 mol% of the aromatic dicarboxylic acid component is represented by the following formula (1)

(R is an alkylene group having 2 to 10 carbon atoms)
Is a 6,6 ′-(alkylenedioxy) di-2-naphthoic acid component, and 90 mol% or more of the glycol component is an ethylene glycol residue.

  A preferred ratio of the 6,6 '-(alkylenedioxy) di-2-naphthoic acid component is 45 mol% or less, further preferably 40 mol% or less, and more preferably 35 mol% or less.

（ｎは１〜３）
で表される。さらに具体的には下記式（１）−２

で表される。 In the 6,6 ′-(alkylenedioxy) di-2-naphthoic acid component represented by the above formula (1), the alkylene group represented by R is preferably a linear aliphatic hydrocarbon group, Furthermore, the number of methylene groups is preferably an even number. More preferably, the following formula (1) -1

(N is 1-3)
It is represented by More specifically, the following formula (1) -2

It is represented by

  In the copolymer polyethylene-2,6-naphthalate of the present invention, 90 mol% or more of the glycolic acid component is an ethylene glycol residue. Below the lower limit, it becomes difficult to maintain the excellent properties of polyethylene-2,6-naphthalate. The proportion of the ethylene glycol residue is preferably in the range of 90 to 100 mol%, more preferably 95 to 100 mol%.

  The intrinsic viscosity of the copolymerized polyethylene-2,6-naphthalate of the present invention is 0.4 to 3.0. The intrinsic viscosity is obtained by dissolving a polymer using a mixed solvent of P-chlorophenol / tetrachloroethane (40/60 weight ratio) to prepare a solution having a polymer concentration of 0.5 g / dL and measuring at 35 ° C.

  The copolymerized polyethylene-2,6-naphthalate of the present invention is not limited to the effects of the present invention, and other aromatic dicarboxylic acid residues such as terephthalic acid residues, phthalic acid residues, isophthalic acid residues. 1,4-phenylenedioxydicarboxylic acid residue, 1,3-phenylenedioxydiacetic acid residue, 4,4′-diphenyldicarboxylic acid residue, 4,4′-diphenyletherdicarboxylic acid residue, 4,4 Copolymerizing a '-diphenyl ketone dicarboxylic acid residue, 4,4'-diphenoxyethanedicarboxylic acid residue, 4,4'-diphenylsulfone dicarboxylic acid residue or 2,7-naphthalenedicarboxylic acid residue As glycol components other than ethylene glycol, isopropylene glycol residue, trimethylene glycol residue, tetramethylene glycol Lumpur residue, hexamethylene glycol residue, octamethylene glycol residue, may be copolymerized, such as diethylene glycol residues.

  The copolymer polyethylene-2,6-naphthalate of the present invention has a melting point measured by DSC of 195 to 260 ° C. by copolymerizing with a 6,6 ′-(alkylenedioxy) di-2-naphthoic acid component. It is preferable from the point of film forming property that it exists in the range and also the range of 200-260 degreeC. When the melting point exceeds the above upper limit, when melt extrusion is performed, the fluidity is inferior, and the discharge is likely to be non-uniform. On the other hand, when it is less than the above lower limit, although the film-forming property is excellent, the mechanical properties of polyethylene-2,6-naphthalate are liable to be impaired. That is, usually, if other acid components are copolymerized and the melting point is lowered, the mechanical properties and the like are lowered at the same time, but surprisingly homopolyethylene-2,6-naphthalate or The present inventors have found that the same mechanical properties as the polymer having the main repeating unit of ester of 6,6 ′-(ethylenedioxy) di-2-naphthoic acid described in Patent Documents 1 to 4 can be expressed. It is an invention.

  In addition, the copolymerized polyethylene-2,6-naphthalate of the present invention is obtained by copolymerizing a 6,6 ′-(alkylenedioxy) di-2-naphthoic acid component, thereby measuring a glass transition temperature (hereinafter referred to as DSC) measured by DSC. Tg) is preferably in the range of 105 to 120 ° C., more preferably in the range of 110 to 120 ° C., from the viewpoint of heat resistance and dimensional stability. Usually, the Tg of homopolyethylene-2,6-naphthalate is about 118 ° C., and since the 6,6 ′-(alkylenedioxy) di-2-naphthoic acid component is selected as the copolymer component, it is less than 50 mol%. Even when the copolymerization is carried out, the copolymer polyethylene-2,6-naphthalate can be provided with Tg equal to or higher than the above lower limit. If Tg is less than the lower limit, the heat resistance and mechanical strength of the resin may be defective.

  The copolymerized polyethylene-2,6-naphthalate of the present invention is identified by copolymerizing polyethylene-2,6-naphthalate with 6,6 ′-(alkylenedioxy) di-2-naphthoic acid in a specific range. It is characterized by having excellent moldability due to its molecular structure.

  The present inventors paid attention to the fact that polyethylene 6,6 ′-(alkylenedioxy) di-2-naphthalate is excellent in dimensional stability. However, the melting point is very high and the crystallinity is also very high. The lack of fluidity in the molten state has been a problem. Therefore, by forming a copolymer having a specific molar ratio of non-liquid crystalline polyethylene-2,6-naphthalate and highly crystalline polyethylene 6,6 ′-(alkylenedioxy) di-2-naphthalate, It is a feature of the present invention to obtain a resin excellent in stability and moldability.

The copolymerized polyethylene-2,6-naphthalate of the present invention is preferably one that does not form an optically anisotropic melt phase.
In the copolymer polyethylene-2,6-naphthalate of the present invention, no peak is observed in the range of 2θ of 5 to 10 ° in the XRD measurement of the amorphous material obtained by melting once at 340 ° C. and then rapidly cooling in an ice bath. It is preferable. The copolymer polyethylene-2,6-naphthalate of the present invention has an endothermic peak of 120 ° C. when the temperature is raised to 320 ° C. at a temperature increase rate of 20 ° C./min in DSC measurement and then cooled at 10 ° C./min. It is preferable that 0 to 1 point is observed in a range of ˜220 ° C., that is, no endothermic peak is observed, or only one endothermic peak is observed.

  Whether the copolymerized polyethylene-2,6-naphthalate forms an optically anisotropic melt phase is controlled by controlling the introduction ratio of the 6,6 ′-(alkylenedioxy) di-2-naphthoic acid component. it can. From this point, the preferable ratio of the 6,6 ′-(alkylenedioxy) di-2-naphthoic acid component in the copolymer polyethylene-2,6-naphthalate of the present invention is 45 mol% or less as described above, and further 40 The mol% or less is preferable, and more preferably 35 mol% or less.

  The copolymer polyethylene-2,6-naphthalate of the present invention preferably contains less than 10 mol% of a dialkylene glycol component as a reaction byproduct. When dialkylene glycol remains in the polymer or an ether component such as dialkylene glycol is contained in the polymer skeleton, the rigidity of the main chain is lost, which causes a decrease in mechanical properties and heat resistance. It is known that such a dialkylene glycol component is produced by reaction between glycol components or reaction between hydroxy ends of polymer ends. When the glycol component is ethylene glycol, diethylene glycol is produced. Therefore, it is desirable to suppress such dialkylene glycol to less than 10 mol%. Preferably it is 7 mol% or less. The content of dialkylene glycol can be measured by a nuclear magnetic resonance apparatus.

  The copolymer polyethylene-2,6-naphthalate of the present invention preferably has a terminal carboxy concentration of 200 equivalent / ton or less, more preferably 100 equivalent / ton or less. In copolymerized polyethylene-2,6-naphthalate, the equilibrium constant of the polycondensation reaction is usually small. Therefore, an increase in the amount of carboxy ends causes an increase in water absorption and an increase in hydrolyzability due to acid catalysis by the carboxy group. There was a problem that the physical properties of the film were impaired. Therefore, in order to improve hydrolysis resistance, it is important to reduce the amount of this carboxy terminal. In addition, when solid phase polymerization is carried out in order to further increase the degree of polymerization of the obtained polyester, if the amount of carboxy ends is large, the reactivity will decrease, and the time required for solid phase polymerization will increase and productivity will decrease. This is also not preferable. In order to obtain copolymer polyethylene-2,6-naphthalate having a terminal carboxy concentration in the above preferred range, for example, 6,6 ′-(ethylenedioxy) di-2-naphthoic acid is passed through its ester compound. This can be achieved by directly reacting with glycol.

(Extensible when forming film)
The copolymerized polyethylene-2,6-naphthalate of the present invention can be subjected to ordinary melt molding such as extrusion molding, injection molding, compression molding, blow molding, and the like, fibers, films, three-dimensional molded articles, containers, hoses, etc. Can be processed. The copolymerized polyethylene-2,6-naphthalate of the present invention has a specific amount of a crystalline 6,6 ′-(alkylenedioxy) di-2-naphthoic acid component as a copolymerized component, so that the copolymerized polyethylene- It is characterized by excellent stretchability when molding 2,6-naphthalate to obtain a film, and in particular, bidirectional stretchability when attempting to obtain a biaxially stretched film.

  When a biaxially stretched film is obtained by melt-forming the copolymer polyethylene-2,6-naphthalate of the present invention and extruding it into a sheet, the excellent heat resistance of polyethylene-2,6-naphthalate It is possible to provide excellent dimensional stability while maintaining mechanical properties and moldability, and in particular, it is possible to reduce the humidity expansion coefficient.

（Ｒは炭素数２から１０のアルキレン基）
で表される６，６’−（アルキレンジオキシ）ジ−２−ナフトエ酸またはそのエステルと
ナフタレン−２，６−ジカルボン酸、またはそのエステルとエチレングリコールとを反応させ重合させることにより製造することができる。 (Production method)
Next, a method for producing the copolymer polyethylene-2,6-naphthalate of the present invention will be described in detail. The copolymerized polyethylene-2,6-naphthalate of the present invention has the following formula (2)

(R is an alkylene group having 2 to 10 carbon atoms)
It is produced by reacting and polymerizing 6,6 ′-(alkylenedioxy) di-2-naphthoic acid or its ester represented by the above and naphthalene-2,6-dicarboxylic acid or its ester and ethylene glycol. Can do.

（ｎは１〜３）
であり、さらに好ましくは下記式（２）−２

で表される。 The 6,6 ′-(alkylenedioxy) di-2-naphthoic acid represented by the above formula (2) is preferably the following formula (2) -1

(N is 1-3)
More preferably, the following formula (2) -2

It is represented by

  By the way, in a method of transesterifying an ester of 6,6 ′-(alkylenedioxy) di-2-naphthoic acid and ethylene glycol as shown in Patent Documents 1 to 4, a large amount of diethylene glycol component is generated as a by-product. It's easy to do. Therefore, in the copolymer polyethylene-2,6-naphthalate of the present invention, in order to make the amount of ethylene glycol within the above range, 6,6 ′-(alkylenedioxy) di-2-naphthoic acid, ethylene glycol, It is preferable to employ a method of esterifying the reaction. The diethylene glycol content can be measured with a nuclear magnetic resonance apparatus. By directly reacting 6,6 '-(alkylenedioxy) di-2-naphthoic acid with glycol without going through its ester compound, the content of by-products such as dialkylene glycol, which is a reaction by-product, is reduced. You can also In addition, you may perform a solid state polymerization process as needed.

  Moreover, it is preferable from the point of the handling in a superposition | polymerization process to use the ethylene glycol component 1.1-4 mol times with respect to all the acid components at the process of manufacturing the above-mentioned polyester precursor. More preferably, it is 1.1-3 times mole, More preferably, it is 1.1-2 times mole.

The reaction temperature for producing the polyester precursor is preferably at or above the boiling point of ethylene glycol, particularly preferably in the range of 190 ° C to 250 ° C. When the temperature is lower than 190 ° C., the reaction does not proceed sufficiently. When the temperature is higher than 250 ° C., glycol as a side reaction product is easily generated. In addition, the reaction can be performed under normal pressure, but the reaction may be performed under pressure in order to further increase productivity. More specifically, the reaction pressure is 10 to 200 kPa in absolute pressure, the reaction temperature is usually 150 to 250 ° C., preferably 180 to 230 ° C., the reaction time is 10 to 10 hours, preferably 30 to 7 minutes. It is preferable to be performed for less than an hour. A reaction product as a polyester precursor is obtained by this esterification reaction.
In the reaction step for producing the polyester precursor, a known esterification or transesterification reaction catalyst may be used.

Next, the polycondensation reaction will be described. First, the polycondensation temperature is from the melting point of the obtained polymer to the melting point + 50 ° C. or less, more preferably from the melting point plus 5 ° C. to the melting point + 30 ° C. or less. In the polycondensation reaction, it is usually preferable to carry out under a reduced pressure of 6.7 × 10 ⁻⁴ MPa or less. If it is higher than 6.7 × 10 ⁻⁴ MPa, the time required for the polycondensation reaction becomes long and it becomes difficult to obtain a copolymerized aromatic polyester resin having a high degree of polymerization.

  Examples of the polycondensation catalyst include metal compounds containing at least one metal element. The polycondensation catalyst can also be used in the esterification reaction. Examples of the metal element include titanium, germanium, antimony, aluminum, nickel, zinc, tin, cobalt, rhodium, iridium, zirconium, hafnium, lithium, calcium, and magnesium. More preferable metals are titanium, germanium, antimony, aluminum, tin, etc. Among them, a titanium compound is particularly preferable because it exhibits high activity in both the esterification reaction and the polycondensation reaction.

  These catalysts may be used alone or in combination. The amount of the catalyst is preferably 0.005 to 0.5 mol%, more preferably 0.01 to 0.1 mol%, based on the number of moles of the repeating unit of the copolymerized aromatic polyester.

  In the copolymerized polyethylene-2,6-naphthalate of the present invention, other thermoplastic polymers, stabilizers such as ultraviolet absorbers, antioxidants, plasticizers, lubricants, flame retardants, as long as the effects of the present invention are not impaired. In addition, a mold release agent, a pigment, a nucleating agent, a filler, glass fiber, carbon fiber, layered silicate, or the like may be blended as necessary. Examples of other types of thermoplastic polymers include polyester resins such as polyethylene terephthalate, polybutylene terephthalate, and the like, polyamide resins, polycarbonate resins, ABS resins, polymethyl methacrylate, polyamide elastomers, and polyester elastomers having a different composition from the above polyester resins. .

  The polyethylene-2,6-naphthalate of the present invention can produce various products by an extrusion molding method, an injection molding method, an extrusion blow molding method, and a calendar molding method, and has particularly excellent dimensional stability. It is extremely suitable as a material for a base film of a high-density magnetic recording medium.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. The characteristics were measured and evaluated by the following methods.

(1) Intrinsic viscosity The intrinsic viscosity of the obtained polyester was adjusted by dissolving the polymer using a mixed solvent of P-chlorophenol / tetrachloroethane (40/60 weight ratio) to a polymer concentration of 0.5 g / dL. It was determined by measuring at 35 ° C.

(2) DSC measurement The glass transition point and the melting point were measured with DSC (TA Instrument Co., Ltd., DSC2920) at a heating rate of 20 ° C / min. Further, for evaluation of liquid crystallinity, an endothermic peak was observed when the temperature was raised to 320 ° C. at a rate of temperature rise of 20 ° C./min and then cooled at 10 ° C./min.

(3) Terminal carboxyl group amount The terminal carboxyl group amount was measured by 600 MHz 1H-NMR (JEOL A-600, manufactured by JEOL Ltd.).

(4) Esterification rate The esterification rate was measured by 600 MHz 1H-NMR (manufactured by JEOL Ltd., JEOL A-600).

(5) Copolymerization amount Copolymerization was measured by 600 MHz 1H-NMR (manufactured by JEOL Ltd., JEOL A-600).

(6) XRD measurement The XRD measurement used the powder X-ray-diffraction apparatus RAD-B made from Rigaku. The sample was measured using an amorphous sample obtained by melting once at 340 ° C. and then rapidly cooling in an ice bath.

(7) Young's modulus The obtained copolymer aromatic polyester resin was melted at a temperature of melting point + 20 ° C. and extruded onto a cooling drum as an unstretched sheet having a thickness of 600 μm. The film was stretched by a factor of 3.4. Thereafter, the obtained film was cut out with a sample width of 10 mm and a length of 15 cm, and placed on a universal tensile tester (product name: Tensilon) manufactured by Toyo Baldwin under the conditions of 100 mm between chucks, 10 mm / min tensile speed, and 500 mm / min chart speed. Pull. The Young's modulus measurement direction is the film forming direction. The Young's modulus is calculated from the tangent of the rising portion of the obtained load-elongation curve.

(8) Temperature expansion coefficient (αt)
The obtained film was cut into a length of 15 mm and a width of 5 mm so that the width direction of the film was a measurement direction, set in TMA3000 manufactured by Vacuum Riko, and pretreated at 60 ° C. for 30 minutes in a nitrogen atmosphere (0% RH). Then, the temperature is lowered to room temperature. Thereafter, the temperature is raised from 25 ° C. to 70 ° C. at 2 ° C./min, the sample length at each temperature is measured, and the temperature expansion coefficient (αt) is 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
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 Is the temperature expansion coefficient (ppm / ° C.) of quartz glass.

(9) Humidity expansion coefficient (αh)
The obtained film was cut into a length of 15 mm and a width of 5 mm so that the width direction of the film would be the measurement direction, set in TMA3000 manufactured by Vacuum Riko, and a humidity of 30% RH and a humidity of 70% under a nitrogen atmosphere at 30 ° C. The length of each sample in RH is measured, and a humidity expansion coefficient is 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 ₇₀ −L ₃₀ ) / (L ₃₀ × ΔH)
Here, L ₃₀ in the above formula is a sample length (mm) at 30% RH, L70 is a sample length (mm) at 70% RH, and ΔH: 40 (= 70-30)% RH. .

[Reference Example 1] Production of bis (β-hydroxyethyl) 6,6 '-(ethylenedioxy) di-2-naphthoic acid 100 parts by weight of 6,6'-(ethylenedioxy) di-2-naphthoic acid, ethylene 62 parts by weight of glycol and 0.085 parts by weight of tetra-n-butyl titanate were placed in an autoclave equipped with a 1 L stirrer and nitrogen gas inlet, and after nitrogen substitution, a nitrogen pressure of 0.2 MPa was applied and the reaction was carried out at 230 ° C. for 6 hours. Went. Crystals deposited after the reaction were filtered and washed with methanol. After washing, vacuum drying was performed at 120 ° C. to obtain 115 parts by weight of bis (β-hydroxyethyl) 6,6 ′-(ethylenedioxy) G-2-naphthoic acid. The degree of esterification of this product was 96%. The melting point was 240 ° C.

[Example 1]
100 parts by weight of bis (β-hydroxyethyl) 6,6 ′-(ethylenedioxy) di-2-naphthoic acid obtained in Reference Example 1, 352 parts by weight of 2,6-bis (hydroxyethoxycarbonyl) naphthalene, tetra-n -0.09 part by weight of butyl titanate was charged into a reactor equipped with a rectifying column and melted at 270 ° C under nitrogen. Thereafter, the pressure was gradually reduced and the reaction was stirred at 500 mmHg for about 20 minutes, and then the polymerization temperature was raised to 320 ° C. Next, the pressure inside the system was gradually further reduced, and the reaction was stirred for about 20 minutes after reaching 0.2 mmHg. The naphthalenedicarboxylic acid component was 87.4 mol%, and 6,6 ′-(ethylenedioxy) di-2-naphthoic acid. Copolymer polyethylene-2,6-naphthalate having a component of 12.6 mol% was obtained. The obtained polymer had an intrinsic viscosity of 0.98, a glass transition temperature of 115 ° C., and a melting point of 238 ° C. Table 1 shows the physical properties of the obtained polymer.

  With respect to the obtained copolymer polyethylene-2,6-naphthalate, no peak was observed in the range of 2θ of 5 to 10 ° in XRD measurement (FIG. 1). Further, the obtained copolymer polyethylene-2,6-naphthalate has an endothermic peak of 120 ° C. to 220 ° C. when the temperature is raised to 320 ° C. at a temperature rising rate of 20 ° C./min in DSC measurement and then cooled at 10 ° C./min. It was not observed in the range of ° C. (FIG. 2).

[Example 2]
In the same manner as in Example 1 except that 100 parts by weight of 6,6 ′-(ethylenedioxy) di-2-naphthoic acid and 145 parts by weight of 2,6-bis (hydroxyethoxycarbonyl) naphthalene were used, naphthalene dicarboxylic acid Copolymer polyethylene-2,6-naphthalate having an acid component of 69.5 mol% and a 6,6 ′-(ethylenedioxy) di-2-naphthoic acid component of 30.5 mol% was obtained. The physical properties of the obtained polymers are shown in Tables 1 and 2. No peak was observed in the range of 2θ of 5 to 10 ° in XRD measurement of the obtained copolymer polyethylene-2,6-naphthalate. . In addition, the obtained copolymer polyethylene-2,6-naphthalate was observed to have one endothermic peak when the temperature was increased to 320 ° C. at a temperature increase rate of 20 ° C./min in DSC measurement and then cooled at 10 ° C./min. (Figure 3).

[Example 3]
In the same manner as in Example 1, except that 100 parts by weight of 6,6 ′-(ethylenedioxy) di-2-naphthoic acid and 93 parts by weight of 2,6-bis (hydroxyethoxycarbonyl) naphthalene were used, naphthalene dicarboxylic Copolymer polyethylene-2,6-naphthalate having an acid component of 62.3 mol% and a 6,6 ′-(alkylenedioxy) di-2-naphthoic acid component of 37.7 mol% was obtained. The physical properties of the obtained polymers are shown in Tables 1 and 2. No peak was observed in the range of 2θ of 5 to 10 ° in XRD measurement of the obtained copolymer polyethylene-2,6-naphthalate. . The obtained copolymer polyethylene-2,6-naphthalate has a main peak of 1 as an endothermic peak when the temperature is increased to 320 ° C. at a temperature increase rate of 20 ° C./min in DSC measurement and then cooled at 10 ° C./min. One point and one minute peak were observed (FIG. 4).

[Example 4]
In the same manner as in Example 1 except that 100 parts by weight of 6,6 ′-(ethylenedioxy) di-2-naphthoic acid and 168 parts by weight of 2,6-bis (hydroxyethoxycarbonyl) naphthalene were used, naphthalene dicarboxylic acid Copolymer polyethylene-2,6-naphthalate having an acid component of 73 mol% and a 6,6 ′-(ethylenedioxy) di-2-naphthoic acid component of 27 mol% was obtained.

  The obtained copolymer polyethylene-2,6-naphthalate was supplied to an extruder and extruded from a die at 290 ° C. in a molten state onto a cooling drum having a temperature of 40 ° C. to form an unstretched film. And 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 140 ° C., and stretching in the vertical direction (film forming direction) is performed. It was performed at the draw ratio described in the middle. Subsequently, the film was stretched in the transverse direction (width direction) at 140 ° C., and the maximum stretching ratio until breaking was obtained (however, the mechanical maximum stretching ratio of the apparatus was 6 times). Further, the film was stretched in the transverse direction (width direction) at a drawing ratio smaller than the maximum drawing ratio until breaking, to obtain a film having a thickness of 8 μm, and the surface ratio was determined from the actual longitudinal and transverse stretching ratio. Table 3 shows the properties of the biaxially oriented polyester film obtained by heat setting at 185 ° C. for 10 seconds.

[Comparative Example 1]
Dimethyl 2,6-naphthalenedicarboxylate and ethylene glycol are subjected to an esterification reaction and a transesterification reaction in the presence of titanium tetrabutoxide, followed by a polycondensation reaction to obtain an intrinsic viscosity of 0.62 dl / g. Polyethylene-2,6-naphthalate in which 1.5 mol% of the glycol component was a diethylene glycol component was obtained. Similarly to Example 4, a biaxially oriented polyester film was obtained at the draw ratio shown in Table 3, and the properties of the obtained biaxially oriented polyester film are shown in Table 3.

[Examples 5 to 7]
In the same manner as in Example 1, a copolymer polyethylene-2,6-naphthalate having a naphthalenedicarboxylic acid component in mol% in Table 4 was obtained, and a film having a thickness of 8 to 10 μm was obtained in the same manner as in Example 4. Table 4 shows the results of film formation to evaluation of the biaxially stretched film.

[Comparative Example 2]
The same kind of polymer as in Example 1 was synthesized by the method described in JP-A-60-135428. Specifically, 458 parts by weight of diethyl 6.6 ′-(ethylenedioxy) g-2-naphthoate, 130 parts by weight of ethylene glycol, and 0.1 part by weight of tetra-n-butyl titanate are charged and heated at 200 ° C. to 260 ° C. The ethanol produced by the reaction was distilled out of the system. Gradually the reaction started to crystallize and solidify. Stirring was once stopped, and after the theoretical amount of ethanol was distilled off, the temperature was raised to 290 ° C. and melted, reacted at normal pressure in a nitrogen gas stream for 30 minutes, then the reaction temperature was raised to 310 ° C. The pressure was gradually reduced and the reaction was continued for another 10 minutes after reaching 0.2 mmHg. The melting point of the obtained polymer was 294 ° C., the diethylene glycol component was 12 mol%, and the alkali metal content was 30 ppm.

  When the esterification exchange reaction is carried out by the method described in JP-A-60-135428, the polyester precursor crystals are precipitated and solidified in the latter stage of the reaction, causing a problem in the stirring step, and the esterification exchange reaction is sufficiently performed. Did not proceed. In addition, it was confirmed that the produced aromatic polyester resin had a large amount of diethylene glycol component and deteriorated thermal properties.

  The copolymerized polyethylene-2,6-naphthalate of the present invention can be subjected to ordinary melt molding such as extrusion molding, injection molding, compression molding, blow molding, and the like, fibers, films, three-dimensional molded articles, containers, hoses, etc. Can be processed. Since it has particularly excellent dimensional stability, it is suitable as a base film for a high-density magnetic recording medium.

2 is an XRD measurement chart of copolymer polyethylene-2,6-naphthalate of Example 1. 2 is a DSC measurement chart of copolymerized polyethylene-2,6-naphthalate of Example 1. 2 is a DSC measurement chart of copolymerized polyethylene-2,6-naphthalate of Example 2. 6 is a DSC measurement chart of copolymerized polyethylene-2,6-naphthalate of Example 3.

Claims (6)

It consists of an aromatic dicarboxylic acid component and an alkylene glycol component, 50 mol% or more and less than 95 mol% of the aromatic dicarboxylic acid component is a naphthalene dicarboxylic acid component, and 5 mol% or more and less than 50 mol% of the aromatic dicarboxylic acid component, Following formula (1)

(R is an alkylene group having 2 to 10 carbon atoms)
In which 90 mol% or more of the glycol component is an ethylene glycol residue, and P-chlorophenol / 1,1,2 is a 6,6 ′-(alkylenedioxy) di-2-naphthoic acid component represented by Copolymer polyethylene-2,6-naphthalate having an intrinsic viscosity of 0.4 to 3.0 measured at 35 ° C. using a mixed solvent of 2,2-tetrachloroethane (weight ratio 40/60) .   The copolymer polyethylene-2,6-naphthalate according to claim 1, having a melting point in the range of 195 to 260 ° C.   The peak according to claim 1 or 2, wherein no peak is observed in the range of 5 to 10 ° of 2θ in an XRD measurement of an amorphous material obtained by melting at 340 ° C and then rapidly cooling in an ice bath. Polymerized polyethylene-2,6-naphthalate.   In DSC measurement, the temperature is increased to 320 ° C. at a rate of temperature increase of 20 ° C./min, and then 0 to 1 endothermic peak is observed in the range of 120 ° C. to 220 ° C. when cooled at 10 ° C./min. Copolymer polyethylene-2,6-naphthalate according to any one of claims 1 to 3.   The copolymerized polyethylene-2,6-naphthalate according to any one of claims 1 to 4, which has a terminal carboxyl group amount of 200 equivalent / ton or less measured by NMR.   The copolymer polyethylene-2,6-naphthalate according to any one of claims 1 to 5, wherein the glass transition temperature in DSC measurement is in the range of 105 to 120 ° C.

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