JP2009108231A - Polyester composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polyester composition having excellent dimensional stability when it is processed into a film etc., and attaining a high Young's modulus even without using an excessive stretching ratio. <P>SOLUTION: The polyester composition contains a polyester whose acid component comprises a 6,6'-(alkylenedioxy)di-2-naphthoic acid component or a dicarboxylic acid component of phenylene- or naphthalene-diyl and whose glycol component is a 2-4C alkylene glycol component and also particles whose area circle equivalent mean diameter of primary particles lies below 100 nm, wherein the acid component of the polyester is characterized by that the content of the 6,6'-(alkylenedioxy)di-2-naphthoic acid lies in the range of 5-80 mol% with respect to the mole number of the total acid components. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polyester composition copolymerized with 6,6 '-(alkylenedioxy) di-2-naphthoic acid and a film using the same.

  Polyesters typified by polyethylene terephthalate and polyethylene-2,6-naphthalate have excellent mechanical properties, dimensional stability, and heat resistance, and thus are widely used for films and the like. In particular, polyethylene-2,6-naphthalate has mechanical properties, dimensional stability, and heat resistance superior to those of polyethylene terephthalate, so that it is used in demanding applications such as a base film for high-density magnetic recording media. in use. However, demands for dimensional stability in high-density magnetic recording media and the like in recent years, particularly demands for dimensional stability against changes in temperature and humidity, are increasing, and further improvement of characteristics is required.

  By the way, it is necessary to reduce the temperature expansion coefficient and the humidity expansion coefficient in order to reduce the dimensional change with respect to changes in temperature and humidity. In the case of polyethylene terephthalate or polyethylene-2,6-naphthalate, the humidity expansion coefficient and the temperature expansion coefficient are required. Both are very closely related to Young's modulus, with higher Young's modulus generally lowering. As a method for increasing the Young's modulus, there are a method for increasing the molecular orientation by increasing the draw ratio and a method for containing a filler (Patent Documents 1 to 4). However, the former method becomes a severe condition as the draw ratio is increased, and it does not become a fundamental solution. There was no effect on it.

  On the other hand, Patent Documents 5 to 7 are obtained from diethyl-6,6 ′-(alkylenedioxy) di-2-naphthoate, which is an ester compound of 6,6 ′-(alkylenedioxy) di-2-naphthoic acid. Polyalkylene-6,6 ′-(alkylenedioxy) di-2-naphthoate has been proposed. According to this publication, polyethylene-6,6 '-(ethylenedioxy) di-2-naphthoate which is crystalline and has a melting point of 294 ° C. is specifically presented.

However, since polyalkylene-6,6 ′-(alkylenedioxy) di-2-naphthoate presented in these patent documents has a very high melting point and very high crystallinity, it should be formed into a film or the like. Then, there was a problem that the fluidity in the molten state was poor and the extrusion became non-uniform, or even when trying to stretch after extrusion, crystallization progressed and the film would break when stretched at a high magnification. In addition, although the humidity expansion coefficient is very small, there is also a problem that the temperature expansion coefficient is very high. Incidentally, referring to the film disclosed in Example 1 of Patent Document 4, the Young's modulus is the direction of film is 485 kg / mm ^2, although the width direction is also 1110kg / mm ^2, the thermal expansion coefficient 16.5~19ppm / ° C and a very high value regardless of the Young's modulus.

JP-A-6-128466 Japanese Unexamined Patent Publication No. 1-144452 JP 2003-82202 A JP 2002-225198 A JP-A-60-135428 JP-A-60-212420 JP 61-145724 A

  An object of the present invention is to provide a novel polyester composition capable of expressing a higher Young's modulus and a lower humidity expansion coefficient when formed into a molded body such as a film.

  The present inventors surprisingly found that when a 6,6 ′-(alkylenedioxy) di-2-naphthoic acid component is used as a copolymerization component, polyalkylene-6,6 ′-(alkylenedioxy) di- It was found that a film having excellent properties of both 2-naphthoate and polyester as a copolymerization partner thereof can be obtained. When the polyester using the 6,6 ′-(alkylenedioxy) di-2-naphthoic acid component as a copolymerization component contains particles having an area equivalent circle diameter of primary particles of less than 100 nm, the same draw ratio is obtained. However, the inventors have found that a molded body such as a film or fiber having a high Young's modulus can be obtained and reached the present invention.

  Thus, according to the present invention, the acid component consists of the following structural formulas (I) and (II), and the ratio of the following structural formula (I) is in the range of 5 to 80 mol% based on the number of moles of the total acid component. And a polyester composition containing a polyester having a glycol component represented by the following structural formula (III) and particles having an average equivalent-area diameter of primary particles of less than 100 nm.

（上記構造式（Ｉ）中のＲ_１は炭素数１〜１０のアルキレン基を、上記構造式（ＩＩ）中のＲ_２はフェニレン基またはナフタレンジイル基、上記構造式（ＩＩＩ）中のＲ_３は炭素数２〜４のアルキレン基を示す。）

(R ₁ in the structural formula (I) is an alkylene group having 1 to 10 carbon atoms, R ₂ in the structural formula (II) is a phenylene group or a naphthalenediyl group, and R ₃ in the structural formula (III). Represents an alkylene group having 2 to 4 carbon atoms.)

  Furthermore, according to the present invention, as a preferred embodiment of the polyester composition of the present invention, the content of particles having an area-equivalent mean diameter of primary particles of less than 100 nm is 0.05 to 10% based on the weight of the composition. %, And at least one of the particles selected from the group consisting of boehmite, alumina, and silica are also provided.

  According to the present invention, while maintaining the characteristic that the excellent coefficient of humidity expansion of polyalkylene-6,6 ′-(alkylenedioxy) di-2-naphthoate is small, the film-forming property can be highly enhanced, As a result, a polyester composition having surprisingly low dimensional stability that has a low temperature expansion coefficient that cannot be predicted from the prior art is obtained, and the polyester composition has an area-equivalent mean diameter of primary particles. Can be formed into a molded body such as a film or a fiber having a higher Young's modulus under the same stretching conditions.

  Therefore, according to the present invention, there is provided a polyester composition for a film that is suitable for a base film of a high-density magnetic recording medium, particularly for applications that require a high degree of dimensional stability and high Young's modulus in consideration of the effects of humidity and temperature. Provided.

<Polyester composition>
In the polyester forming the polyester composition of the present invention, the acid component consists of the structural formula (I) and the structural formula (II), and the glycol component consists of the structural formula (III).
Specific examples of the acid component represented by the structural formula (I) are those in which R ₁ is an alkylene group having 1 to 10 carbon atoms, and preferably 6,6 ′-(ethylenedioxy) di -2-naphthoic acid component, 6,6 ′-(trimethylenedioxy) di-2-naphthoic acid component and 6,6 ′-(butyleneoxy) di-2-naphthoic acid component, etc. Among these, from the viewpoint of the effect of the present invention, those having an even number of carbon atoms of R ₁ in the general formula (I) are preferred, and in particular, 6,6 ′-(ethylenedioxy) di having 2 carbon atoms of R _1. A 2-naphthoic acid component is preferred.

  Examples of the acid component represented by the structural formula (II) include a terephthalic acid component, an isophthalic acid component, a 2,6-naphthalenedicarboxylic acid component, and a 2,7-naphthalenedicarboxylic acid component. Among these, a terephthalic acid component and a 2,6-naphthalenedicarboxylic acid component are preferable from the viewpoint of mechanical properties, and a 2,6-naphthalenedicarboxylic acid component is particularly preferable.

  Specific examples of the glycol component represented by the structural formula (III) include an ethylene glycol component, a trimethylene glycol component, a tetramethylene glycol component, and the like. The mol% or more is preferably an ethylene glycol component, and more preferably 95 to 100 mol% is an ethylene glycol component.

  By the way, one of the characteristics of the present invention is that the 6,6′- represented by the structural formula (I) is in the range of 5 to 80 mol% based on the number of moles of the total acid component among the acid components of the polyester. (Alkylenedioxy) di-2-naphthoic acid component is copolymerized. When the ratio of the 6,6 '-(alkylenedioxy) di-2-naphthoic acid component is less than the lower limit, the effect of reducing the humidity expansion coefficient is hardly exhibited. On the other hand, the upper limit is preferably 80 mol% or less, and more preferably less than 50 mol% from the viewpoint of moldability. Surprisingly, the 6,6 '-(alkylenedioxy) di-2-naphthoic acid component reduces the coefficient of humidity expansion very efficiently in a small amount and is less than 50 mol%. In addition, a humidity expansion coefficient equivalent to or lower than that of the film described in the example of Patent Document 3 has been achieved, and it can be said that the effect from the viewpoint of the humidity expansion coefficient is saturated even when the upper limit is added. From such a viewpoint, the upper limit of the copolymerization amount of the preferred 6,6 ′-(alkylenedioxy) di-2-naphthoic acid component is 45 mol% or less, further 40 mol% or less, and further 35 mol% or less. In particular, it is 30 mol% or less, and the other lower limit is 5 mol% or more, further 7 mol% or more, still more 10 mol% or more, particularly 15 mol% or more.

  By using a polyester obtained by copolymerizing such a specific amount of 6,6 ′-(alkylenedioxy) di-2-naphthoic acid component, a molded product having a low temperature expansion coefficient and a low humidity expansion coefficient, such as a film, is produced. can do.

  The polyester in the present invention may be copolymerized with other copolymerization components known per se within a range not impairing the effects of the present invention, or may be blended with a polyetherimide or a liquid crystalline resin. .

  Next, the polyester according to the present invention preferably has a melting point measured by DSC in the range of 200 to 260 ° C., further in the range of 210 to 255 ° C., particularly in the range of 220 to 253 ° C. from the viewpoint of film forming property. When the melting point exceeds the above upper limit, when molding by melt extrusion, it is necessary to make the temperature higher to increase the fluidity, and it tends to be thermally deteriorated, and on the other hand, if the melting temperature is lowered, the fluidity is inferior, Discharge is likely to be non-uniform. On the other hand, when the ratio is less than the above lower limit, the film forming property is excellent, but the mechanical properties of the polyester are easily impaired. In general, if other acid components are copolymerized to lower the melting point, the mechanical properties and the like are reduced at the same time. However, the film forming property is improved, or the mechanical properties and the like can be improved.

  Further, the polyester in the present invention has a glass transition temperature (hereinafter sometimes referred to as Tg) measured by DSC in the range of 90 to 119 ° C, more preferably in the range of 95 to 118 ° C, particularly in the range of 100 to 117 ° C. It is preferable from the viewpoint of heat resistance and dimensional stability. Such a melting point and glass transition temperature can be adjusted by controlling the type and amount of copolymerization component, dialalkylene glycol as a byproduct.

  By the way, the polyester composition of the present invention needs to contain particles whose upper limit of the area-equivalent circle average diameter of the primary particles is less than 100 nm from the viewpoint of expressing a higher Young's modulus when formed into a molded body, It is preferable to contain particles whose upper limit of the area circle equivalent average diameter of the primary particles is less than 50 nm. Since such fine particles are dispersed in the polyester composition, the mechanical properties such as Young's modulus can be improved because the movement of the molecular chain is restricted. On the other hand, the lower limit of the area equivalent circle diameter of the primary particles contained is usually 0.5 nm or more, and 1.0 nm or more because it is easy to express the Young's modulus improvement effect to a higher degree by suppressing aggregation of the primary particles. Further, it is preferably 5 nm or more. The primary particles in the present invention are observed as the smallest unit particles that cannot be further separated by observation with a transmission electron microscope, which will be described later, and the average equivalent area diameter of the primary particles is orthogonal as described later. The area equivalent circle diameters of primary particles observed from three directions are averaged.

  In addition, the polyester composition of the present invention has a particle content of 0.05% by weight or more, preferably 0.07% based on the weight of the polyester composition, from the viewpoint of improving the Young's modulus of the molded article obtained. It is preferably contained in an amount of not less than wt%, more preferably not less than 0.1 wt%. When the content is less than the lower limit, the number of particles is small, and the effect of improving the Young's modulus is hardly exhibited. Note that the upper limit of the content is usually 10% by weight based on the weight of the polyester composition, because when used as a base film of a high-density magnetic recording medium, the flatness of the film surface is easily maintained to a higher degree. Hereinafter, it is further preferably 5% by weight or less. When particles having an area equivalent circle diameter of primary particles of 100 nm or more or 50 nm or more coexist, the content of particles having an area circle equivalent average diameter of the primary particles equal to or less than the upper limit is calculated as follows. First, create a chart of particle size distribution with the horizontal axis as the equivalent area diameter of primary particles and the vertical axis as the frequency of primary particles, and extract the valleys that are less than half of the adjacent peak and the lowest frequency. Then, primary particles included between adjacent valleys are determined as a group of particles. Then, the content of the particle group satisfying the area circle equivalent average diameter of the primary particles was defined as the content of particles having an area circle equivalent average diameter of the primary particles equal to or less than the upper limit.

  The aforementioned particles in the present invention are not particularly limited as long as the area equivalent circle diameter of the primary particles satisfies the scope of the present invention, but from the viewpoint of heat resistance and dispersibility, boehmite, alumina and It is preferably at least one kind of particles selected from the group consisting of silica.

  The boehmite particles are not particularly limited as long as they satisfy the above characteristics, but the primary particles are preferably plate-shaped or needle-shaped, and needle-shaped particles are particularly preferable from the viewpoint of the effect of the present invention. The alumina particles are not particularly limited as long as they satisfy the above-mentioned characteristics, but the main crystal form is at least one selected from γ, δ, and θ because the effects of the present invention are more easily obtained. Is preferred. The silica particles are not particularly limited as long as they satisfy the above characteristics, and can be produced by a water glass method or an alkoxide method.

  By the way, the polyester composition and the film of the present invention need only contain particles satisfying the area circle equivalent average diameter of the primary particles as described above, and are not limited to a single component system, but may have other particle diameters and compositions different from each other. Particles may be used in combination. In addition to the improvement of Young's modulus, the particles whose average diameter equivalent to the area circle of the primary particles exceeds the above-mentioned upper limit are included in order to provide the molded article such as a film with excellent handleability. Specific examples of the particles include known organic particles and inorganic particles.

<Molded product>
The polyester composition of the present invention can be formed into a film by melting and forming into a sheet. When used as a base film such as a magnetic tape, it is preferable that at least one direction in the film surface direction has a high Young's modulus of 6.0 GPa or more so that the base film does not stretch due to stress applied to the film. Further, by providing the film having such a high Young's modulus, it is possible to reduce the humidity expansion coefficient and the temperature expansion coefficient. The preferred Young's modulus is 5.1 to 11 GPa in the longitudinal direction of the film, more preferably in the range of 5.2 to 10 GPa, particularly 5.5 to 9 GPa, and 5.0 to 11 GPa in the width direction of the film, further 6 to 10 GPa. In particular, it is in the range of 7-10 GPa.

<Method for producing polyester composition>
Below, the manufacturing method of the polyester composition in this invention is explained in full detail.
First, ester 6,6 ′-(alkylenedioxy) di-2-naphthoic acid or an ester-forming derivative thereof such as 2,6-naphthalenedicarboxylic acid or terephthalic acid or an ester-forming derivative thereof and ethylene glycol, for example. The polyester precursor is produced by the reaction of esterification or transesterification. The polyester precursor thus obtained may be polymerized in the presence of a polymerization catalyst, and solid phase polymerization or the like may be performed as necessary. The intrinsic viscosity measured at 35 ° C. using a mixed solvent of P-chlorophenol / 1,1,2,2-tetrachloroethane (weight ratio 40/60) of the polyester thus obtained is 0.4 to 1. 0.5 dl / g, and more preferably in the range of 0.5 to 1.3 dl / g is preferable from the viewpoints of handleability and mechanical properties. Two types of polymers having different proportions of the above structural formulas (I) and (II) can be prepared and melt kneaded so that the proportions of the above structural formulas (I) and (II) are aimed. Good.

  In addition, the glycol component such as an ethylene glycol component is used 1.1 to 6 times, further 2 to 5 times, particularly 3 to 5 times the number of moles of the total acid component in the step of producing the polyester precursor. It is preferable from the viewpoint of productivity.

  The reaction temperature for producing the polyester precursor is preferably higher than the boiling point of a glycol component such as ethylene glycol, and 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., a dialkylene glycol such as diethylene glycol, which is a side reaction product, is likely to be 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 or transesterification reaction.

  In the reaction step for producing the polyester precursor, a known esterification or transesterification reaction catalyst may be used. For example, an alkali metal compound, an alkaline earth metal compound, a titanium compound, and the like can be given.

  Next, the polycondensation reaction will be described. First, the polycondensation temperature is in the range of a temperature not lower than the melting point of the obtained polyester 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 copolyester having a high degree of polymerization.

  Examples of the polycondensation catalyst include metal compounds containing at least one metal element. In addition, you may use together a polycondensation catalyst as a catalyst of esterification reaction or transesterification. 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, titanium compounds are particularly preferable because they exhibit high activity in both esterification reaction, transesterification reaction and polycondensation reaction. .

  These catalysts may be used alone or in combination. The amount of the catalyst is preferably 0.001 to 0.5 mol%, more preferably 0.005 to 0.2 mol%, based on the number of moles of the repeating unit of the copolyester.

  By the way, the addition method of the aforementioned particles is not particularly limited, and a known addition method can be employed. For example, a method of adding particles in the state of a glycol slurry in the polymerization reaction stage, a method of melt-kneading particles with a kneading extruder to the obtained polymer, and the like can be mentioned. From the viewpoint of particle dispersibility, a particle master polymer of a polyester composition containing particles at a high concentration is prepared by adding particles in a glycol slurry state in the polymerization reaction stage, and the particle master polymer contains particles. It is preferred to dilute with no polyester.

  The polyester composition of the present invention includes other thermoplastic polymers, stabilizers such as ultraviolet absorbers, antioxidants, plasticizers, lubricants, flame retardants, mold release agents, and pigments, as long as the effects of the present invention are not impaired. Further, a nucleating agent, a filler or glass fiber, carbon fiber, layered silicate, etc. may be blended as necessary. Examples of other types of thermoplastic polymers include aliphatic polyester resins, polyamide resins, polycarbonates, ABS resins, polymethyl methacrylate, polyamide elastomers, polyester elastomers, polyetherimides, polyimides, and the like.

<Film production method>
The polyester composition of the present invention is used as a raw material, dried, and then supplied to an extruder heated to a temperature of the melting point (Tm: ° C.) to (Tm + 50) ° C. of the polyester composition. Extrude into a sheet. In addition, the polyester composition of the present invention to be used is not limited to one type, for example, a polymer having a large proportion of the above structural formula (I) and a polymer having a large amount of the above structural formula (II) are prepared. They may be used by being melt-kneaded so that the ratio of the formulas (I) and (II) is within the target range. By adopting such a method, the above structural formulas (I) and (II) The ratio can be arbitrarily and easily changed. The extruded sheet can be rapidly cooled and solidified with a rotating cooling drum or the like to form an unstretched film, and the unstretched film can be biaxially stretched to obtain a biaxially oriented film.

  In addition, from the viewpoint of facilitating the later-described stretching, it is preferable to perform cooling with a cooling drum very quickly, not at a high temperature of 80 ° C. as described in Patent Document 3, but at a low temperature of 20-60 ° C. It is preferable to do so. 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.

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 polyester at 3 to 8 times, and then at a higher temperature than the previous longitudinal stretching (Tg + 10) in the transverse direction. It is preferable that the film is stretched 3 to 8 times at a temperature of (Tg + 50) ° C., and further heat-treated at a temperature not higher than the melting point of the polymer and at a temperature of (Tg + 50) to (Tg + 150) ° C. for 1 to 20 seconds. The heat setting time is preferably 1 to 15 seconds.

  Normally, when the stretch ratio is increased, the film-forming stability is impaired, but the polyester composition according to the present invention has very high stretchability, so there is no such problem, and in particular, the stretch ratio is higher. Therefore, it is particularly useful for a thin film having a thickness of 10 μm or less, more preferably 8 μm or less. The lower limit of the thickness of the film is not particularly limited, but is usually about 1 μm, preferably 3 μm.

  In the above description, sequential biaxial stretching has been described. However, simultaneous biaxial stretching in which longitudinal stretching and lateral stretching are simultaneously performed can also be produced. For example, the stretching ratio and the stretching temperature described above may be referred to.

  Further, when the biaxially oriented polyester film is a laminated film, two or more kinds of molten polyester compositions are laminated in a die and then extruded into a film, preferably the melting point (Tm: ° C.) to ( Extrude at a temperature of Tm + 70) ° C., or extrude two or more molten polyester compositions from a die, laminate them, rapidly solidify them to form a laminated unstretched film, and then apply the same method as in the case of the above-mentioned single-layer film. Axial stretching and heat treatment may be performed. At this time, it is not necessary that all the film layers are the polyester composition of the present invention, and it is sufficient that at least one film layer is made of the polyester composition of the present invention. In addition, a coating layer may be provided on the surface of the biaxially oriented film. In that case, a desired coating solution is applied to one side or both sides of the unstretched film or the uniaxially stretched film described above, and after that, Biaxial stretching and heat treatment are preferably performed in the same manner as in the case.

  According to the present invention, a biaxially oriented polyester film comprising the polyester composition of the present invention is used as a base film, a nonmagnetic layer and a magnetic layer are formed in this order on one side, and a backcoat layer is formed on the other side. By forming it, a magnetic recording tape can be obtained.

  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.

(1) Intrinsic viscosity The intrinsic viscosity of the obtained polyester was measured at 35 ° C by dissolving the polymer using a mixed solvent of P-chlorophenol / 1,1,2,2-tetrachloroethane (40/60 weight ratio). And asked.

(2) Copolymerization amount For the glycol component, 10 mg of a sample was dissolved in 0.5 ml of a mixed solution of p-chlorophenol: 1,1,2,2-tetrachloroethane = 3: 1 (volume ratio) at 80 ° C. amine was added, measured at 80 ° C. at ¹ 600M after thorough mixing H-NMR (Hitachi Denshi Ltd. JEOL A600), were measured each glycol component amount.
As for the aromatic dicarboxylic acid component, 50 mg of a sample was dissolved in 0.5 ml of a mixed solution of p-chlorophenol: 1,1,2,2-tetrachloroethane = 3: 1 at 140 ° C., and 400 M ¹³ C-NMR ( Hitachi Electron JEOL A600) was measured at 140 ° C., and the amount of each acid component was measured.

(3) Young's modulus The obtained film was cut out with a sample width of 10 mm and a length of 15 cm, and a universal tensile testing apparatus (product name: Toyo Baldwin, trade name: 100 mm between chucks, tensile speed 10 mm / min, chart speed 500 mm / min). Pull with Tensilon). The Young's modulus is calculated from the tangent of the rising portion of the obtained load-elongation curve.

(4) 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 (× 10 ⁻⁶ / ° C.) of quartz glass.

(5) 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) when 30% RH, L ₇₀ is a sample length (mm) when 70% RH, ΔH: 40 (= 70-30)% RH is there.

(6) Area equivalent circle diameter of primary particles (nm)
The polyester composition containing the particles is formed into a chip shape and sliced with an ultramicrotome in a direction perpendicular to the major axis direction of the chip. The sliced ultrathin section has a thickness of 200 nm. Then, the cross section of the ultrathin slice sliced in each direction is magnified 200,000 times with a transmission electron microscope, the smallest unit particle that cannot be separated is taken as the primary particle, and the individual areas of 300 primary particles in each cross-sectional direction The equivalent circle diameter was determined, and the area equivalent circle diameters in the three cross-sectional directions, that is, the average value of 900 area equivalent circle diameters was defined as the area equivalent circle average diameter of the primary particles.

(7) Content of particles A solvent that dissolves polyester but does not dissolve particles is selected. After the polyester composition is dissolved, the particles are centrifuged from the polyester, and the ratio of the weight of the particles to the total weight of the polyester composition (weight) %) Is the particle content. In addition, when a plurality of types of particles are used in combination, a particle size distribution is created from the measurement of the area circle equivalent average diameter of the primary particles, and the ratio of the abundance of each particle is obtained. And what is necessary is just to obtain | require content of each particle | grain from the content of the particle | grains calculated | required by the above-mentioned centrifugation and the ratio of the above-mentioned particle existence amount.

[Example 1]
Dimethyl 2,6-naphthalenedicarboxylate, 6,6 ′-(ethylenedioxy) di-2-naphthoic acid and ethylene glycol were subjected to esterification and transesterification in the presence of titanium tetrabutoxide, and then further The polycondensation reaction was carried out to give an intrinsic viscosity of 0.66 dl / g, 73 mol% of the acid component being 2,6-naphthalenedicarboxylic acid component, and 27 mol% of the acid component being 6,6 ′-(alkylenedioxy). A polyester was obtained in which 98 mol% of the di-2-naphthoic acid component and glycol component were ethylene glycol components and 2 mol% were diethylene glycol components. The polyester contained acicular boehmite particles as shown in Table 1 before the polycondensation reaction. This polyester had a melting point of 240 ° C. and a glass transition temperature of 117 ° C.

The polyester thus obtained was supplied to an extruder and extruded from a die at 290 ° C. onto a cooling drum having a rotating temperature of 50 ° C. to form 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 135 ° C., and stretching in the machine 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, stretched at 140 ° C. in the transverse direction (width direction) at a stretching ratio of 6.3 times, then heat-set at 200 ° C. for 10 seconds, and biaxially stretched with a thickness of 6 μm. A film was obtained.
The properties of the obtained polyester composition and biaxially oriented polyester film are shown in Table 1.

[Examples 2 and 3]
In Example 1, the same operation was repeated except that the particles to be contained were changed as shown in Table 1.
The properties of the obtained polyester composition and biaxially oriented polyester film are shown in Table 1.

[Comparative Example 1]
The same operation as in Example 1 was repeated except that Example 1 was changed so as not to contain particles.
The properties of the obtained polyester composition and biaxially oriented polyester film are shown in Table 1.

[Comparative Example 2]
In Example 1, the same operation was repeated except that the particles to be contained were changed as shown in Table 1.
The characteristics of the obtained biaxially oriented polyester film are shown in Table 1.

[Example 4]
Dimethyl 2,6-naphthalenedicarboxylate, 6,6 ′-(ethylenedioxy) di-2-naphthoic acid and ethylene glycol were subjected to esterification and transesterification in the presence of titanium tetrabutoxide, and then further The polycondensation reaction was carried out, the intrinsic viscosity was 0.72 dl / g, 94 mol% of the acid component was 2,6-naphthalenedicarboxylic acid component, and 6 mol% of the acid component was 6,6 ′-(alkylenedioxy). A polyester was obtained in which 99 mol% of the di-2-naphthoic acid component and glycol component were an ethylene glycol component and 1 mol% was a diethylene glycol component. The polyester contained acicular boehmite particles as shown in Table 1 before the polycondensation reaction. This polyester had a melting point of 255 ° C. and a glass transition temperature of 119 ° C.

The polyester thus obtained was supplied to an extruder and extruded from a die at 290 ° C. onto a cooling drum having a rotating temperature of 50 ° C. to form an unstretched film. Then, between the two sets of rollers having different rotation 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 machine direction (film forming direction) is performed. A uniaxially stretched film was obtained at a magnification of 5.3 times. Then, this uniaxially stretched film is guided to a stenter, stretched in the transverse direction (width direction) at 140 ° C. at a stretch ratio of 4.0 times, and then heat-set at 200 ° C. for 10 seconds, and biaxially stretched with a thickness of 8 μm A film was obtained.
The properties of the obtained polyester composition and biaxially oriented polyester film are shown in Table 1.

[Example 5]
Dimethyl 2,6-naphthalenedicarboxylate, 6,6 ′-(ethylenedioxy) di-2-naphthoic acid and ethylene glycol were subjected to esterification and transesterification in the presence of titanium tetrabutoxide, and then further The polycondensation reaction was carried out, the intrinsic viscosity was 0.77 dl / g, 80 mol% of the acid component was 2,6-naphthalenedicarboxylic acid component, and 20 mol% of the acid component was 6,6 ′-(alkylenedioxy). A polyester was obtained in which 99 mol% of the di-2-naphthoic acid component and glycol component were an ethylene glycol component and 1 mol% was a diethylene glycol component. The polyester contained acicular boehmite particles as shown in Table 1 before the polycondensation reaction. The polyester had a melting point of 252 ° C. and a glass transition temperature of 116 ° C.

The polyester thus obtained was supplied to an extruder and extruded from a die at 290 ° C. onto a cooling drum having a rotating temperature of 50 ° C. to form 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 135 ° C., and stretching in the machine direction (film forming direction) is performed. A uniaxially stretched film was obtained at a magnification of 5.5. Then, this uniaxially stretched film is led to a stenter, stretched at a stretching ratio of 4.3 times in the transverse direction (width direction) at 140 ° C., and then heat-set at 210 ° C. for 10 seconds, and biaxially stretched with a thickness of 6 μm. A film was obtained.
The properties of the obtained polyester composition and biaxially oriented polyester film are shown in Table 1.

[Example 6]
Dimethyl 2,6-naphthalenedicarboxylate, 6,6 ′-(ethylenedioxy) di-2-naphthoic acid and ethylene glycol were subjected to esterification and transesterification in the presence of titanium tetrabutoxide, and then further The polycondensation reaction was performed, and the intrinsic viscosity was 0.75 dl / g, 65 mol% of the acid component was 2,6-naphthalenedicarboxylic acid component, and 35 mol% of the acid component was 6,6 ′-(alkylenedioxy). A polyester was obtained in which 98 mol% of the di-2-naphthoic acid component and glycol component were ethylene glycol components and 2 mol% were diethylene glycol components. The polyester contained acicular boehmite particles as shown in Table 1 before the polycondensation reaction. This polyester had a melting point of 247 ° C. and a glass transition temperature of 116 ° C.

The polyester thus obtained was supplied to an extruder and extruded from a die at 290 ° C. onto a cooling drum having a rotating temperature of 50 ° C. to form an unstretched film. Then, between the two sets of rollers having different rotation 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 machine direction (film forming direction) is performed. A uniaxially stretched film was obtained at a magnification of 5.5. Then, this uniaxially stretched film is guided to a stenter, stretched at 140 ° C. in the transverse direction (width direction) at a stretch ratio of 6.0 times, and then heat-set at 210 ° C. for 10 seconds to be biaxially stretched with a thickness of 7 μm A film was obtained.
The properties of the obtained polyester composition and biaxially oriented polyester film are shown in Table 1.

[Example 7]
Dimethyl 2,6-naphthalenedicarboxylate, 6,6 ′-(ethylenedioxy) di-2-naphthoic acid and ethylene glycol were subjected to esterification and transesterification in the presence of titanium tetrabutoxide, and then further The polycondensation reaction was carried out, the intrinsic viscosity was 0.70 dl / g, 30 mol% of the acid component was 2,6-naphthalenedicarboxylic acid component, and 70 mol% of the acid component was 6,6 ′-(alkylenedioxy). A polyester was obtained in which 98 mol% of the di-2-naphthoic acid component and glycol component were ethylene glycol components and 2 mol% were diethylene glycol components. The polyester contained acicular boehmite particles as shown in Table 1 before the polycondensation reaction. This polyester had a melting point of 268 ° C. and a glass transition temperature of 101 ° C.

The polyester thus obtained was supplied to an extruder and extruded from a die at 300 ° C. in a molten state onto a cooling drum having a temperature of 50 ° C. and rotating into a sheet to obtain 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 135 ° C., and stretching in the machine direction (film forming direction) is performed. A uniaxially stretched film was obtained at a magnification of 4.0. And this uniaxially stretched film is led to a stenter, stretched at 140 ° C. in the transverse direction (width direction) at a stretching ratio of 3.8 times, then heat-set at 200 ° C. for 10 seconds, and biaxially stretched with a thickness of 10 μm. A film was obtained.
The properties of the obtained polyester composition and biaxially oriented polyester film are shown in Table 1.

[Examples 8 and 9]
In Example 1, the same operation was repeated except that the content of acicular boehmite particles was changed as shown in Table 1.
The properties of the obtained polyester composition and biaxially oriented polyester film are shown in Table 1.

[Example 10]
Esterification and transesterification of dimethyl terephthalate, 6,6 '-(ethylenedioxy) di-2-naphthoic acid and ethylene glycol in the presence of titanium tetrabutoxide, followed by polycondensation reaction And the intrinsic viscosity is 0.68 dl / g, 80 mol% of the acid component is terephthalic acid component, 20 mol% of the acid component is 6,6 ′-(alkylenedioxy) di-2-naphthoic acid component, glycol component A polyester having 98 mol% of ethylene glycol component and 2 mol% of diethylene glycol component was obtained. The polyester contained acicular boehmite particles as shown in Table 1 before the polycondensation reaction. This polyester had a melting point of 230 ° C. and a glass transition temperature of 85 ° C.

The polyester thus obtained was supplied to an extruder and extruded from a die at 290 ° C. onto a cooling drum having a rotating temperature of 50 ° C. to form 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 105 ° C., and stretching in the longitudinal direction (film forming direction) is performed. A uniaxially stretched film was obtained at a magnification of 5.0. Then, this uniaxially stretched film is guided to a stenter, stretched at 115 ° C. in the transverse direction (width direction) at a stretch ratio of 5.0 times, then heat-set at 210 ° C. for 3 seconds, and biaxially stretched with a thickness of 10 μm. A film was obtained.
The properties of the obtained polyester composition and biaxially oriented polyester film are shown in Table 1.

[Comparative Example 3]
In Example 4, the same operation as in Example 4 was repeated except that the particle was not contained.
The properties of the obtained polyester composition and biaxially oriented polyester film are shown in Table 1.

[Comparative Example 4]
The same operation as in Example 5 was repeated except that Example 5 was changed so as not to contain particles.
The properties of the obtained polyester composition and biaxially oriented polyester film are shown in Table 1.

[Comparative Example 5]
In Example 6, the same operation as in Example 6 was repeated except that the particle was not contained.
The properties of the obtained polyester composition and biaxially oriented polyester film are shown in Table 1.

[Comparative Example 6]
In Example 7, the same operation as in Example 7 was repeated except that the particle was not contained.
The properties of the obtained polyester composition and biaxially oriented polyester film are shown in Table 1.

[Comparative Example 7]
In Example 10, the same operation as in Example 10 was repeated except that the particle was not contained.
The properties of the obtained polyester composition and biaxially oriented polyester film are shown in Table 1.

[Comparative Example 8]
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. The polyethylene-2,6-naphthalate contains silica particles having an average particle diameter of 0.5 μm before the polycondensation reaction so that the amount is 0.2% by weight based on the weight of the resin composition obtained. Contained. This polyethylene-2,6-naphthalate had a melting point of 270 ° C. and a glass transition temperature of 120 ° C.

The polyethylene-2,6-naphthalate thus obtained was supplied to an extruder and extruded from a die at 300 ° C. in a molten state onto a cooling drum at a temperature of 60 ° C. during rotation to form an unstretched film. . Then, between the two sets of rollers having different rotation 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 machine direction (film forming direction) is performed. A uniaxially stretched film was obtained at a magnification of 3.0. And this uniaxially stretched film is led to a stenter, stretched at a stretching ratio of 4.3 times in the transverse direction (width direction) at 140 ° C., and then heat-set at 200 ° C. for 10 seconds to be biaxially stretched with a thickness of 10 μm. A film was obtained.
The characteristics of the obtained biaxially oriented polyester film are shown in Table 1.

[Comparative Example 9]
In Comparative Example 8, the stretching temperature in the film forming direction was 140 ° C., the stretching ratio in the film forming direction was 4.0 times, the stretching temperature in the width direction was 140 ° C., and the stretching ratio in the width direction was 4.0 times. The same operation was repeated except that the heat setting treatment temperature was changed to 200 ° C. to obtain a biaxially stretched film.
The characteristics of the obtained biaxially oriented polyester film are shown in Table 1.

[Comparative Example 10]
In Comparative Example 8, the stretching temperature in the film forming direction is 140 ° C., the stretching ratio in the film forming direction is 4.5 times, the stretching temperature in the width direction is 140 ° C., and the stretching ratio in the width direction is 3.4 times. The same operation was repeated except that the heat setting treatment temperature was changed to 200 ° C. to obtain a biaxially stretched film.
The characteristics of the obtained biaxially oriented polyester film are shown in Table 1.

  In Table 1, NA is 2,6-naphthalenedicarboxylic acid component, TA is terephthalic acid component, ENA is 6,6 '-(ethylenedioxy) di-2-naphthoic acid component, EG is ethylene glycol component, and DEG is diethylene glycol. Component, f is a volume spherical coefficient, MD is a film forming direction, TD is a film width direction, αh is a humidity expansion coefficient, and αt is a temperature expansion coefficient.

  The polyester composition of the present invention can be used as a material such as a film, a bottle or a fiber. In particular, when a biaxially oriented polyester film is used, since it has a high Young's modulus and excellent dimensional stability, it can be suitably used particularly as a base film for a high-density magnetic recording medium.

Claims (3)

The acid component comprises the following structural formulas (I) and (II), and the proportion of the following structural formula (I) is in the range of 5 to 80 mol% based on the number of moles of the total acid component, and the glycol component A polyester composition comprising: a polyester having a structural formula (III) below; and particles having an area equivalent circle diameter of primary particles of less than 100 nm.

(R ₁ in the structural formula (I) is an alkylene group having 1 to 10 carbon atoms, R ₂ in the structural formula (II) is a phenylene group or a naphthalenediyl group, and R ₃ in the structural formula (III). Represents an alkylene group having 2 to 4 carbon atoms.)   The polyester composition according to claim 1, wherein the content of the particles is 0.05 to 10% by weight based on the weight of the composition.   The polyester composition according to claim 1, wherein the particles are at least one kind of particles selected from the group consisting of boehmite, alumina, and silica.