JP2001323142A - Polyester composition and film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polyester film almost free from coarse projection and defects, and excellent in surface properties, oligomer deposition-inhibiting properties and productivity. SOLUTION: The polyester composition comprises a 20-60C ester compound comprising a higher aliphatic carboxylic acid and a higher aliphatic alcohol and gives X and Y simultaneously satisfying following equations (1) and (2); 0.1<=X<=10 (1), Y/X<=0.4 (2), wherein X (wt.%) is a weight ratio of the ester compound to the polyester and Y (wt.%) is a weight ratio of the polyester compound contained in a solution, obtained by dissolving the polyester composition in a hexafluoroisopropanol/chloroform mixed solvent, adding to the resultant solution a hexane/toluene mixed solvent and removing insoluble matters therefrom.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester composition and a film, and more particularly, to a polyester composition and a film which are excellent in oligomer precipitation inhibitory property and have few coarse projections and defects.

[0002]

2. Description of the Related Art Polyester films, especially polyethylene terephthalate (hereinafter referred to as PET) films are widely used in industrial applications due to their excellent mechanical, thermal and electrical properties, and their demand is increasing. However,
With the expansion of applications and demand, the properties and productivity required for polyester are becoming increasingly severe in each application field, and while being produced in a wide variety of applications such as industrial and magnetic materials, There are many issues to be addressed.

[0003] When a polyester film is used as a magnetic recording medium, coarse projections and defects on the surface must be reduced as much as possible from the viewpoint of high recording density. There's a problem. Polyester produces an oligomer as a by-product during its polymerization, and in the case of PET, contains about 1 to 3% by weight of an oligomer mainly composed of an ethylene terephthalate cyclic trimer. These oligomers precipitate and form coarse projections. In particular, when used as a magnetic material film, coarse projections based on such surface-precipitated oligomers cause data loss in the magnetic layer, and thus one problem is how to suppress surface-precipitated oligomers.

A solution to such a problem is disclosed in
As disclosed in Japanese Patent Application Laid-Open No. 8-145418, there was a technique of adding an ester of an aliphatic monocarboxylic acid to suppress the deposition of low molecular weight substances such as oligomers on a drum during film formation. The formation of coarse protrusions on the film surface due to foreign matter contained in the additive was a problem, and the effect of suppressing oligomer precipitation after film formation was insufficient. Further, as described in JP-A-11-188825, addition of an additive such as an alkali metal salt of an organic sulfonic acid suppresses oligomer precipitation on the film surface. However, there is a problem that a film-like defect occurs and the film-forming property is deteriorated. These techniques are not suitable for use as a magnetic recording medium, especially from the viewpoint of forming a smooth surface.

[0005]

SUMMARY OF THE INVENTION An object of the present invention is to provide a polyester film which has few coarse projections and defects, is excellent in surface properties, is excellent in oligomer precipitation suppressing properties, and is excellent in productivity.

[0006]

An object of the present invention is to provide a polyester composition comprising an ester compound having 20 to 60 carbon atoms, comprising a higher aliphatic carboxylic acid and a higher aliphatic alcohol, and a polyester, The amount ratio of the ester compound to the polyester is X% by weight, the polyester composition is dissolved in a mixed solvent of hexafluoroisopsanol / chloroform, and a mixed solvent of hexane / toluene is added to remove the insolubilized substance. When the amount ratio of the ester compound to the polyester composition is Y weight%, X and Y are as follows:
The problem can be solved by a polyester composition characterized by simultaneously satisfying the expression (2).

[0007] 0.1 ≦ X ≦ 10 (1) Y / X ≦ 0.4 (2)

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention comprises a higher aliphatic carboxylic acid and a higher aliphatic alcohol having 20 to 6 carbon atoms.
0 ester compound, for example, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, higher fatty acid components having 10 to 30 carbon atoms such as behenic acid, undecyl alcohol, lauryl alcohol, 1 carbon atoms such as myristyl alcohol, hexadecanol, stearyl alcohol, and olein alcohol
It means a so-called synthetic wax compound obtained by subjecting 0 to 30 higher aliphatic alcohol components to an ester reaction, or a so-called natural wax such as carnauba wax or insect wax (hereinafter referred to as higher aliphatic carboxylic acid and higher fatty acid). An ester compound of an aliphatic alcohol is simply referred to as a higher aliphatic ester compound). The total carbon number of the higher aliphatic ester compound is preferably from 24 to 50, more preferably from 26 to 46. When the number of carbon atoms is less than 20, the scattering rate in the addition / kneading process becomes high. Carbon number 60
If it exceeds, the compatibility with the polyester decreases. In addition, since natural waxes are derived from natural products, the mixing ratio of foreign substances is high, and from these viewpoints, synthetic waxes such as myristyl stearate, palmityl palmitate, and stearyl stearate are preferably used. One of these compounds may be added, or a mixture of a plurality of compounds may be added.

In the polyester composition of the present invention, the amount of the higher aliphatic ester compound added to the polyester is X% by weight, and the polyester composition is dissolved in a mixed solvent of hexafluoroisopsopanol / chloroform.
After removing the insolubilized product by adding a toluene mixed solvent, the amount ratio of the higher aliphatic ester compound contained in the solvent to the polyester composition is set to Y weight%, and X, Y
Satisfy the following expressions (1) and (2): 0.1 ≦ X ≦ 10 (1) Y / X ≦ 0.4 (2)

Furthermore, it is preferable that the following expressions (3) and (4) are satisfied simultaneously: 0.5 ≦ X ≦ 8 (3) Y / X ≦ 0.3 (4)

If X is less than 0.1% by weight, sufficient oligomer precipitation inhibiting ability cannot be obtained. When X exceeds 10% by weight, the polymerization reactivity decreases when added during polymerization,
Addition with a kneader or the like not only causes problems such as poor extrusion, but also lowers the heat resistance of the polymer. Further, when Y / X exceeds 0.4, when the polyester is formed into a melt film, decomposed products are liable to be scattered from the die, and the die and the casting drum are soiled, thereby lowering the productivity. The ability to inhibit oligomer precipitation also decreases. In addition, Y here shows the content of the low molecular weight compound soluble in the hexane / toluene mixed solvent in the polyester composition. It is presumed that this low molecular weight substance is easily scattered in the film forming process. On the other hand, the insolubilized substance is a high molecular weight substance, and it is considered that the polyester and the higher aliphatic ester component are bound in some form. (1)
The method for producing the polyester of the present invention to satisfy the formula and the formula (2) will be described later.

In the present invention, the polyester composition preferably contains an ethylene terephthalate component as a main component in view of heat resistance and mechanical properties, but other copolymer components such as various dicarboxylic acids or ester-forming derivatives thereof and diols May be added to impart further properties such as heat resistance, high rigidity, and antistatic properties.

The dicarboxylic acid component that can be copolymerized includes:
For example, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 1,5-naphthalenedicarboxylic acid, 2,6
-Naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid, 4,4'-diphenyletherdicarboxylic acid, 4,4'-diphenylsulfonedicarboxylic acid, and ester-forming derivatives thereof. Other examples of the alicyclic dicarboxylic acid component that can be copolymerized include 1,4-cyclohexanedicarboxylic acid. In addition, aliphatic dicarboxylic acids such as sebacic acid and dimer acid, and other dicarboxylic acids can be used as the copolymerization component.

The diol component includes ethylene glycol, 1,2-propanediol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexane. Diol, 1,2-cyclohexanedimethanol, 1,
Aliphatic, alicyclic, aromatic, such as 3-cyclohexane dimethanol, 1,4-cyclohexane dimethanol, diethylene glycol, triethylene glycol, polyalkylene glycol, 2,2-bis (4'-β-hydroxyethoxyphenyl) propane; Group diols and the like. Only one of these components may be used.
More than one species may be used in combination.

In the esterification and transesterification, a conventionally known catalyst can be used. Examples include acetates such as calcium acetate, magnesium acetate, lithium acetate and the like.

As the polymerization catalyst, those which are liable to become foreign matters of metal due to reduction of the catalyst or the like are as few as possible.
Or it is preferable not to use it. Specifically, since the conventionally known diantimony trioxide or titanium-based compound is easily reduced during the reaction to form a metal foreign substance, the polyester composition of the present invention is preferably polymerized using a germanium compound. And particularly polymerized using germanium oxide. Germanium oxide
It is suitable because it is not reduced during the reaction and becomes a metal foreign substance. Germanium oxide compounds include crystalline compounds and amorphous compounds. Crystalline compounds are preferably added in advance as a solution with an alkaline compound such as an amine compound and mainly glycol, and It is preferable to add a crystalline material in a solution in glycol at a temperature of about 100 to 150 ° C. in advance.

The polyester composition of the present invention can be produced according to a conventionally known polyester production method.

That is, a dialkyl ester is used as an acid component, a transesterification reaction is performed between the dialkyl ester and a diol component, and the product of this reaction is heated under reduced pressure to conduct polycondensation while removing the excess diol component. Can be manufactured. It can also be produced by a conventionally known direct polymerization method using a dicarboxylic acid as an acid component.

Further, the polyester thus obtained is
By performing solid phase polymerization, oligomers such as cyclic trimers can be reduced, and the degree of polymerization can be further increased. Solid-state polymerization is carried out under a nitrogen flow or a reduced pressure of 66.5 Pa or less at a temperature in the range of 180 ° C. to the melting point.
It is performed by heating for 〜50 hours.

The timing and method of adding the higher aliphatic ester compound are not particularly limited, and a method of adding 0.1 to 10% by weight as a total amount to the low polymer before the polycondensation reaction step, stirring and mixing, Alternatively, a method of adding and kneading before the completion of the polycondensation reaction to obtain a polyester composition, or a method of kneading to a polyester chip using a twin-screw kneading extruder, etc. It is preferable from the viewpoint of process simplicity and quality stability.

In order to produce the polyester of the present invention which satisfies the ranges of the formulas (1) and (2), the kneading time should be as long as possible in both cases of adding during polymerization and kneading to chips. is necessary. Specifically, for example, in the case of adding before the end of the polymerization reaction, the inside of the system is returned to a vacuum again, and then for 30 minutes or more, preferably 60 minutes or more.
The kneading / repolymerization reaction is performed for at least 90 minutes, more preferably at least 90 minutes. [Η] of the polyester before addition is 0.1.
It is preferably at most 75, more preferably at most 0.72. If the [η] before addition exceeds 0.75, the viscosity difference between the higher aliphatic ester compound and the polyester is large,
The dispersibility is reduced, and the higher aliphatic ester compound is easily phase-separated in the polyester to form an independent domain, and as a result, Y / X is increased. In addition, such phase-separated higher aliphatic ester compounds cause contamination of a die and a casting drum during melt extrusion. As can be seen from the above, Y and Y / X are preferably as small as possible, and most preferably 0. If the value of [η] before the addition is 0.72 or less and the kneading time after the addition is sufficiently long, the values of Y and Y / X are almost zero.
It is also possible to use

If necessary, the higher aliphatic ester compound is preferably added after being filtered through a filter having an opening of 2 μm or less, and more preferably filtered through a filter having an opening of 1.5 μm or less. . In particular,
Filtration using a cartridge filter is preferred. The opening of the filter is preferably as small as possible, but if the opening is too small, the filtration rate is reduced due to the high viscosity of the higher aliphatic ester compound. Is preferred. In particular,
In the case of a natural wax compound, a large amount of coarse foreign matter derived from a natural product is contained.If added as it is, the foreign matter forms coarse projections on the surface when a film is formed. In applications where a sophisticated surface design is required, such a filtration operation is very important. Preferably, a synthetic wax obtained by an esterification reaction of a higher fatty acid and a higher aliphatic alcohol as described above is more preferably used than a natural wax, since foreign substances can be controlled from a raw material. In this case, low filtration pressure during filtration is also an important factor in terms of productivity, and from this viewpoint, the upper limit of the total number of carbon atoms constituting the wax is preferably 60 or less. .

The polyester film of the present invention contains the polyester composition thus obtained, and its content is preferably 1 to 100% by weight, more preferably 5 to 100% by weight. The content can be appropriately changed by preliminarily dry-blending with another polyester and then feeding the extruder to the extruder. However, when the amount containing the polyester composition of the present invention is less than 1% by weight, the content is uniformly increased. It is difficult and undesirable to blend. By changing the content of the polyester composition of the present invention, the content of the higher aliphatic ester compound in the film can be changed. At this time, it is preferable to blend the higher aliphatic ester compound in the obtained film so that the total amount thereof is 0.1% by weight to 2% by weight. If it is less than 0.1% by weight, sufficient oligomer precipitation inhibitory properties cannot be obtained. If the amount exceeds 2% by weight, the higher aliphatic ester compound or a decomposition product thereof may cause problems such as soiling of the base during the film forming step or bleeding out to the film surface after the film formation.

The polyester film of the present invention is obtained by subjecting the polyester composition of the present invention to dry blending with another polyester composition as required, and then extruding it from a die in a conventional manner to form an unstretched sheet. Subsequently, it can be manufactured by biaxial stretching and heat treatment.

In the case of forming a laminated film, each polyester composition is laminated with two or more merging blocks each having a rectangular laminated portion so that each layer is laminated in a desired thickness ratio and configuration. Can be produced in the same manner as in the case of the single film except that the film is fed and extruded from a die. By adopting the laminated structure, for example, when actually used as a base film of a magnetic tape, it becomes possible to design a surface in consideration of the affinity, the smoothness, and the like with the magnetic layer and the back coat layer. Specifically, it is possible to design a surface that distinguishes between the magnetic layer side and the back coat layer side.
It is preferable that the structure has at least two layers. With a configuration of two or more layers, it is possible to develop various applications depending on the variation of the polymer supplied to each layer. Specific examples of such a laminated polyester film of the present invention include a two-layer laminated polyester film composed of an A layer containing the polyester composition of the present invention and a B layer not containing the polyester composition of the present invention. Further, a coating layer such as an easy-adhesion component for a magnetic substance is formed on the layer B side, or a laminate of three or more layers of a polyester composition, wherein both outer layers do not contain the polyester composition of the present invention, Examples include those in which the inner layer contains the polyester composition of the present invention. Such a constitution is not limited to these, and it is possible to develop various kinds by controlling the laminated constitution and the polyester composition content of each layer.

Also, in order to give the film a lubricity,
Inorganic or organic particles may be appropriately blended.

The inorganic particles are not particularly limited, and include compounds such as silica, alumina, calcium carbonate, titanium oxide, calcium phosphate, hydroxyapatite, and aluminum silicate. In addition, examples of the organic particles include crosslinked polymer particles.

These particles may be contained by using a particle-containing master polymer to which the particles are added during the polyester polymerization step, or by adding and kneading the particles to the polyester using a twin-screw extruder or the like. Is also good. Also,
The particle-containing solution may be coated in-line or off-line coated on the film in the film forming step, and dried to form a particle layer.

The biaxial stretching may be any of longitudinal and transverse sequential stretching or simultaneous biaxial stretching, and the stretching ratio is not particularly limited. It is. Alternatively, after stretching in the longitudinal and transverse directions, the film may be stretched again in any of the longitudinal and transverse directions. Further, when forming an easy-adhesion layer, a particle layer, or the like, the coating component may be applied in-line before stretching, or between longitudinal stretching and transverse stretching,
Offline coating may be performed after stretching.

The thus obtained film preferably has a heat treatment index of 60 or less, more preferably 50 or less. In the case of a film having a heat treatment index of more than 60, oligomers are liable to precipitate on the surface as the film is stored for a long time. For example, when used in a magnetic recording medium, this causes recording defects or clogs the magnetic recording head. May cause.

When the film of the present invention is used as a magnetic tape, the number of coarse projections having a longest diameter of 2 μm or more is preferably 20 / mm ² or less, more preferably 1 / mm ² or less.
It is 5 / mm ² or less. If the number of coarse projections exceeds 20 / mm ² , in applications such as a magnetic recording medium, contact with a magnetic recording and reading head becomes unstable, and troubles such as missing data are likely to occur.

The polyester composition of the present invention, particularly when formed into a film, has few coarse projections and defects, and is excellent in oligomer precipitation controllability and productivity, and is particularly suitable as a film for magnetic recording media. In addition, oligomer contamination during production is reduced, and oligomer-based contamination is not generated on the film surface even when the storage period of the film is prolonged. Therefore, it is useful for applications such as optical materials, packaging materials, and electrical insulation materials.

[0033]

The present invention will be described in more detail with reference to the following examples. In addition, each characteristic in an Example was measured by the following method.

A. Intrinsic viscosity of polymer ([η]): o-
It measured at 25 degreeC using chlorophenol as a solvent.

B. Amount of low molecular weight compound contained in the polyester composition 0.3 g of the polyester composition was dissolved by adding 2 cc of a 1: 1 mixed solvent of chloroform / hexafluoropropanol and left standing at room temperature for 24 hours, and then diluted by adding 5 cc of chloroform. Then, 40 cc of a 1: 1 mixed solvent of toluene / hexane was added to insolubilize the high molecular weight components. Further, after adding 50 cc of toluene and diluting, insoluble materials are filtered and
After removal, the filtrate was concentrated with evaporate, filtered, and then subjected to GPC analysis (column: TSKgel GMHHR-L 7.8 ×
The amount of the higher aliphatic ester compound was quantified using a 300 mm mobile phase (toluene), and this was defined as Y (% by weight relative to the polyester composition).

C. Film-forming properties were evaluated as 特 に if there was no particular problem at the time of film-forming, and × if white smoke came out of the base or the casting drum was soiled.

D. Heat treatment index A film (a) having exactly the same structure as that of the film (b) for which the heat treatment index is to be obtained, except that the film does not contain a higher aliphatic ester compound, such as a film thickness, a lamination structure, and a lamination thickness, is prepared.

Leave in an oven at 150 ° C. for 30 minutes,
A low molecular weight substance such as an oligomer is forcibly deposited on the film surface, aluminum is evaporated on the surface, and 10 fields of view are observed with a differential interference microscope at a total magnification of 400 times. The number of low molecular weight substances such as oligomers in each field of view is counted, and the total number is converted into the number of precipitated surface oligomers (pieces / mm ² ). Is calculated by the following equation. Heat treatment index = B / A × 100.

E. Coarse protrusions on the film surface The film surface is aluminum-deposited, and 10 fields of view are observed with a differential interference microscope at a total magnification of 400 times. The number of coarse projections corresponding to the longest diameter of 2 μm in each visual field was counted, and the total number was converted into the number per unit area (pieces / mm ² ).

Reference Example 1 Production of polyethylene terephthalate polymer (PL):
To a mixture of 100% by weight of dimethyl terephthalate and 60% by weight of ethylene glycol, 0.04% by weight of magnesium acetate was added based on the amount of dimethyl terephthalate.
The ester exchange reaction was carried out by heating and raising the temperature by a conventional method.
Next, 0.02% by weight of trimethyl phosphate based on the amount of dimethyl terephthalate was added to the transesterification reaction product.
Was added, and further, 0.02% by weight of germanium oxide was added, and the mixture was transferred to a polycondensation reaction layer. Then, the reaction system was gradually decompressed while heating and the temperature was raised, and polymerization was carried out at 290 ° C. under a reduced pressure of 66.5 Pa or less by an ordinary method, and the intrinsic viscosity [η] =
0.61 of polyethylene terephthalate was obtained.

Reference Example 2 Production of Particle-Containing Polyester Chip (PS): Before moving to the polycondensation reaction layer, a 5% by weight ethylene glycol slurry of silica particles having a particle diameter of 0.05 μm was used in an amount of 5% by weight based on the amount of dimethylterephthalate. Was obtained in the same manner as in PET except that 1% by weight was added.

Example 1 0.04% by weight of magnesium acetate was added to a mixture of 100% by weight of dimethyl terephthalate and 60% by weight of ethylene glycol based on the amount of dimethyl terephthalate.
The ester exchange reaction was carried out by heating and raising the temperature by a conventional method.
Next, 0.02% by weight of trimethyl phosphate based on the amount of dimethyl terephthalate was added to the transesterification reaction product.
Was added, and further, 0.02% by weight of germanium oxide was added, and the mixture was transferred to a polycondensation reaction layer. Then, heating
The reaction system was gradually depressurized while stirring, and was polymerized at 285 ° C. under a reduced pressure of 66.5 Pa or less by a conventional method, and when the stirring torque was increased to an intrinsic viscosity [η] = 0.68, the reaction system was Was returned to normal pressure, and 2.0% by weight of stearyl stearate filtered through a cartridge filter having a mesh size of 2 μm was added. Thereafter, the pressure inside the system was reduced again to 133 Pa or lower over 30 minutes, and after kneading for 90 minutes, the inside of the system was leaked with nitrogen and discharged to obtain a polyester composition having [η] = 0.55. As a result of analysis of the polyester composition, Y = 0.14% by weight and Y / X = 0.07. (This polyester composition is called J1). The results are shown in Table 1.

Examples 2 to 7 Polymerization was carried out in the same manner as in Example, except that the additives, the amount of addition, [η] before addition, and the kneading time under reduced pressure were set to the values shown in the table.
Polyester compositions J2 to J7 were obtained. Table 1 shows the results.

Example 8 Carnauba wax was used as an additive. Before the addition, filtration was performed in the same manner as in Example 1. However, because the filtration pressure was extremely high, and foreign substances due to natural products were larger than synthetic waxes such as stearyl stearate, the filter clogged immediately, and the required amount was reduced. 3 filter changes were required to obtain The polymerization reaction and the physical properties of the polyester were at acceptable levels. Table 1 shows the results.

Example 9 Stearyl stearate obtained by filtration through a filter having a mesh size of 2.0 μm was charged into a hopper A with a liquid kneader in a molten state at 80 ° C.
The polyester (PL) obtained in the above was charged, and stearyl stearate and polyester were supplied from hoppers A and B to a vent-type twin-screw extruder so that stearyl stearate was 2.0% by weight based on the polyester. The mouth was maintained at a vacuum of 1.3 KPa, and kneaded so as to obtain a polyester at a temperature of 280 ° C. and a residence time of 40 minutes. Y
Although the value of / X was at an acceptable level, it was a high value as compared with the addition at the time of polymerization.

Comparative Example 1 Polymerization was attempted in the same manner as in Example 1 except that the amount of stearyl stearate was changed to 15% by weight. When the inside of the system was returned to vacuum again, severe bumping was observed. In addition, the stirring torque did not increase at all after 90 minutes of the repolymerization, and the polymer did not recover with the degree of polymerization lowered. An attempt was made to discharge, but the viscosity was low and no polymer chips were obtained.

Comparative Example 2 A polyester (H1) was obtained in the same manner as in Example 1 except that after adding stearyl stearate, the inside of the system was again evacuated and discharged immediately. The obtained polyester had a high Y / X and a low [η].

Comparative Example 3 A polyester composition was obtained in the same manner as in Example 1, except that the value of [η] before addition was increased to 0.76. Y / X showed a high value.

Comparative Example 4 A polyester was obtained in the same manner as in Example 9 except that the screw alignment, the supply amount and the number of revolutions were changed so that the residence time was 20 minutes. Y / X showed a value probably because the residence (kneading) time was short.

Examples 10 and 11 Polyesters were obtained in the same manner as in Examples 1 and 8, except that the additives were not filtered. Y / X values were acceptable.

Example 12 PL, PS, and J1 were dry-blended so that the weight ratio thereof was 50:30:20, dried at 160 ° C. for 3 hours, supplied to an extruder, and melt-extruded on a casting drum. After being fused and quenched and solidified on the cast drum while applying antistatic power, an unstretched film was obtained.
The film was stretched 3.5 times vertically at 0 ° C. and 3.5 times horizontally at 105 ° C. to obtain a polyester film having a thickness of 8 μm. There is no particular problem in the film-forming properties, and the film thus obtained is shown in Table 2.
As shown in Fig. 7, the number of coarse projections was small, the heat treatment index was low, and good oligomer precipitation inhibiting properties were exhibited. Table 2 shows the results.

Examples 13 to 20 Polyester films were obtained in the same manner as in Example 12, except that J2 to J9 were dry blended at the weight fractions shown in the table instead of J1. Both the coarse projections on the surface and the oligomer precipitation inhibiting properties were at acceptable levels. Table 2 shows the results
Shown in

Examples 21 and 22 Polyester films were obtained in the same manner as in Example 12, except that J10 and J11 were dry-blended at the weight fractions shown in the table instead of J1. The oligomer precipitation inhibiting property was at an acceptable level. However, because of the large number of coarse projections on the surface, it seemed to be unsuitable for applications requiring formation of a fine surface such as a magnetic material. Table 2 shows the results.

Example 23 The melt extrusion die was changed from one layer to one having three layers of A / B / A, and two raw material supply hoppers A and B were attached to the extruder. In the A layer, a weight ratio of PL and PS is 70:30.
After drying and dry blending, PL and J1 are supplied to the B layer at a weight ratio of 80:20, and the thickness ratio of A / B / A is 1 Twelfth example, except that it was extruded to be / 6/1.
A polyester film having a thickness of 8 μm was obtained in the same manner as described above. Even when the polyester composition of the present invention was contained in the inner layer, good oligomer precipitation inhibitory properties were exhibited. Table 2 shows the results.

Comparative Example 5 A polyester film was obtained in the same manner as in Example 12 except that only PL and PS were used as the polymer. The film had no oligomer precipitation inhibiting property.

Comparative Examples 6 to 8 Polyester films were obtained in the same manner as in Example 12, except that H1 to H3 were dry-blended at the weight fractions shown in the table instead of J1. In each case, white smoke was generated from the extrusion die during film formation. None of the obtained films had an oligomer precipitation-inhibiting property that reached an acceptable level.

[0057]

[Table 1]

[0058]

[Table 2]

[0059]

Industrial Applicability The polyester composition and film of the present invention are polyester films excellent in oligomer precipitation inhibitory property and productivity. For example, when used as a film for a magnetic recording medium, even if used for a long time, data loss occurs. It is very suitable because it does not cause such disadvantages as above.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4F071 AA44 AC10 AE04 AF43Y AH14 BA01 BB06 BB08 BC01 BC14 4F100 AA26A AH02A AH08A AK41A AT00B BA07 GB41 JG06 4J002 CF051 CF061 CF071 EH026 EH036 FD026

Claims (7)

[Claims] 1. A polyester composition comprising a polyester having 20 to 60 carbon atoms and a polyester, comprising a higher aliphatic carboxylic acid and a higher aliphatic alcohol, wherein a ratio of the ester compound to the polyester is X weight. %, The polyester composition is dissolved with a mixed solvent of hexafluoroisopsopanol / chloroform, and a mixed solvent of hexane / toluene is added to remove the insolubilized substance. After that, the amount of the ester compound contained in the solvent with respect to the polyester composition When the ratio is defined as Y weight%, X and Y satisfy the following formulas (1) and (2) at the same time. 0.1 ≦ X ≦ 10 (1) Y / X ≦ 0.4 (2) 2. The polyester composition according to claim 1, wherein the ester compound is filtered through a filter having a mesh size of 2 μm or less. 3. The polyester composition according to claim 1, which contains a germanium compound. 4. A polyester film comprising the polyester composition according to claim 1. 5. The polyester film according to claim 4, wherein the heat treatment index is 60 or less. 6. The number of coarse projections having a longest diameter of 2 μm or more is 20 / m.
The polyester film according to claim 4, which has a m ² or less. 7. A laminated film comprising two or more layers,
A laminated polyester film, wherein at least one of the layers is the polyester film according to any one of claims 4 to 6.