JP6467834B2 - Polyester resin composition - Google Patents

Description

  The present invention relates to a polyester resin composition comprising polyester and polyetherimide as main components. More specifically, by containing each atom of pentavalent phosphorus, alkali metal and alkaline earth metal in a specified amount range, the heat resistance is improved and gelation is suppressed, and the film forming property and surface property are excellent. The present invention relates to a polyester resin composition.

  Polyester is excellent in crystallinity, strength, chemical resistance, and transparency, and is used in various applications such as films, fibers, bottles, and extruded products. Among them, the film is used in various fields because of its excellent mechanical properties and economy, and its usefulness in magnetic recording is particularly well known. However, in recent years, magnetic recording media are required to have high density recording. In order to achieve higher density recording, increase the dimensional stability of the tape, use a thin magnetic layer and fine magnetic particles, and disperse the fine magnetic particles highly, thereby increasing the surface of the magnetic layer. It is effective to increase the smoothness of the recording medium, shorten the recording wavelength, and reduce the recording track.

  As a polyester film having high dimensional stability, a biaxially oriented polyester film made of polyethylene terephthalate and polyetherimide is known. However, in the coexistence of polyester and polyetherimide, the decomposition of the polyetherimide is caused by the generation of water and radicals generated by the decomposition of the polyester, and further the decomposition product of the polyetherimide accelerates the decomposition of the polyester, There is a problem that the heat resistance of the polyester is deteriorated, causing the generation of gel-like foreign matters, which causes defects on the film surface.

  As a method for suppressing gelation in a biaxially oriented polyester film composed of polyester and polyetherimide, for example, Patent Document 1 proposes a method of adding a trivalent phosphorus-based antioxidant.

  However, the above-described method is insufficient as an effect of suppressing the degradation of polyetherimide and the gelation of polyester, and it is slightly low when the recording track is made small for high density recording which has been required in recent years. Even if it is a fault on a film, there exists a problem that it becomes a cause of a lack of data and breakage, and suppression of further gelation is requested | required. Further, when a large amount of an antioxidant is added, there is a problem that the film-forming property becomes poor, and the surface property is deteriorated due to bleed-out to the film surface.

JP 2009-179739 A

  The object of the present invention is to solve the above-mentioned conventional problems, improve the heat resistance of the polyester containing polyetherimide, and suppress the generation of foreign matters due to gelation, and has excellent film forming properties and surface properties. To provide things.

The object of the present invention is a polyester resin composition comprising polyester and polyetherimide as main components, containing 820 to 2000 ppm of pentavalent phosphorus atoms, and alkali metal atoms and alkaline earths of the polyester resin composition. This can be achieved by a polyester resin composition characterized in that the content of metal atoms and phosphorus atoms ( the content of alkali metal atoms is 2.4 ppm or more) satisfies the following formula (1).
0.02 ≦ (M1 / 2 + M2) /P≦0.05 (1)
[In the above formula (1), M1 is the total number of moles of alkali metal atoms in the polyester resin composition, M2 is the total number of moles of alkaline earth metal atoms in the polyester resin composition, and P is phosphorus in the polyester resin composition. Represents the total number of moles of atoms. ]

  According to the present invention, in a polyester resin composition comprising polyester and polyetherimide as main components, each atom of pentavalent phosphorus, alkali metal, and alkaline earth metal is contained in a specified amount range, thereby providing a polyester resin. The heat resistance of the composition is improved, the generation of foreign matters due to gelation is suppressed, the film forming property is excellent, and an excellent surface property can be obtained when a film is formed.

  The polyester in the present invention is not particularly limited, but ethylene terephthalate, ethylene-2,6-naphthalate, propylene terephthalate, butylene terephthalate, hexamethylene terephthalate, cyclohexanedimethylene terephthalate, propylene-2,6-naphthalate, butylene-2, The main component is preferably at least one structural unit selected from 6-naphthalate, hexamethylene-2,6-naphthalate, cyclohexanedimethylene-2,6-naphthalate unit, and the like. Among these, polyesters having ethylene terephthalate as a main structural unit are particularly preferable because of excellent molding processability. Two or more kinds of polyesters may be mixed, or copolymerized polyesters may be used.

  When the polyester used in the present invention is polyethylene terephthalate, it is usually produced by one of the following processes. That is, (1) a process in which terephthalic acid and ethylene glycol are used as raw materials, a low polymer is obtained by direct esterification reaction, and a high molecular weight polyester is obtained by subsequent polycondensation reaction, and (2) dimethyl terephthalate and ethylene glycol are used as raw materials. In this process, a low polymer is obtained by a transesterification reaction, and a high molecular weight polyester is obtained by a subsequent polycondensation reaction. Here, in the transesterification reaction, a commonly known transesterification catalyst which is a compound such as manganese, zinc, lithium, or titanium may be added.

  The polyetherimide in the present invention is a polymer containing an aliphatic, alicyclic or aromatic ether unit and a cyclic imide group as repeating units, and is not particularly limited as long as it is a polymer having melt moldability. Examples thereof include polyetherimides described in U.S. Pat. No. 4,141,927 and Japanese Patent No. 2622678, and polymers described in Japanese Patent No. 2,598,536 and JP-A-9-48852. As long as the effect of the present invention is not impaired, the main chain of polyetherimide contains a structural unit other than cyclic imide and ether units, for example, aromatic, aliphatic, alicyclic ester units, oxycarbonyl units, and the like. May be.

  Among them, 2,2-bis [4- (2,3-dicarboxyphenoxy) phenyl] propane dianhydride and m-phenylenediamine or p-phenylenediamine are preferred from the viewpoint of compatibility with polyester and melt moldability. And a polymer having a repeating unit represented by the following formula is preferred.

Or

  This polyetherimide is available from SABIC Innovative Plastics under the trade name “Ultem” (registered trademark), and is “Ultem 1000”, “Ultem 1010”, “Ultem 1040”, “Ultem 5000”, “Ultem 6000” and “Ultem XH6050”. "Series" and "Extreme XH" and "Extem UH" are well-known trademark names.

  In the present invention, it is preferable from the viewpoint of heat resistance that the weight fraction of polyetherimide in the polyester resin composition is 2 to 60% with respect to the polyester resin composition containing polyester and polyetherimide as main components. The method for producing the polyester composition of the present invention is not particularly limited, and polyetherimide may be added before the esterification or transesterification reaction of the polyester, or after the polymerization, the polyetherimide is added to the polymerization apparatus. However, a method in which polyester and polyetherimide are introduced into an extruder and melt kneaded is preferable in order to make the two types of polymers well compatible.

The measuring method of the ratio of polyester and polyetherimide in the polyester resin composition is as follows.
That is, the polyester resin composition of the present invention is dissolved in hexafluoroisopropanol / chloroform as a solvent, and the NMR spectrum of 1H nucleus is measured. In the obtained spectrum, the peak area intensity of absorption specific to polyester and polyetherimide (for example, absorption of aromatic proton of terephthalic acid in the case of polyethylene terephthalate, absorption of proton of imide aromatic in polyetherimide) is obtained, The molar ratio of the blend is calculated from the ratio and the number of protons. Further, the weight ratio is calculated from the formula amount corresponding to the unit unit of each polymer. The measurement conditions are as follows.
Apparatus: BRUKER DRX-500 (Bruker)
Solvent: HFIP / deuterated chloroform Observation frequency: 499.8 MHz
Standard: TMS (0 ppm)
Measurement temperature: 30 ° C
Observation width: 10 KHz
Data point: 64K
acquisition time: 4.952 seconds pulse delay time: 3.048 seconds Integration count: 256 times The polyester resin composition of the present invention needs to contain 820 to 2000 ppm of pentavalent phosphorus atoms. A preferable content is 1050 to 1850 ppm, more preferably 1250 to 1750 ppm. By containing a pentavalent phosphorus atom in a specified range, it is possible to suppress the decomposition of the polyetherimide and to suppress the gelation of the polyester. If it is less than 820 ppm, the effect of inhibiting the decomposition of the polyetherimide by pentavalent phosphorus will be insufficient and cause gelation of the polyester. When it exceeds 2000 ppm, the film-forming property when the polyester resin composition is used as a film becomes poor, and further, the surface property is deteriorated due to bleeding out of the phosphorus compound on the film surface. When a phosphorus compound other than pentavalent is used, suppression of gelation becomes insufficient, or surface properties are deteriorated due to bleeding out when a polyester resin composition is used as a film.

  Although it does not specifically limit as a phosphorus compound added in order to make the polyester composition of this invention contain a pentavalent phosphorus atom, From a viewpoint of suppressing decomposition | disassembly of polyetherimide, a triethyl phosphono acetate and a trimethyl phosphate are preferable.

  In the present invention, as a method for incorporating a pentavalent phosphorus atom into the polyester resin composition, from the viewpoint of uniformly dispersing in the polyester resin composition and the productivity of the polyester, pentavalent at the time of kneading the polyester and polyetherimide. A method of kneading these phosphorus compounds is preferred.

In the polyester resin composition of the present invention, the content of alkali metal atoms, alkaline earth metal atoms, and phosphorus atoms ( content of alkali metal atoms is 2.4 ppm or more) needs to satisfy the following formula (1). In addition, the alkaline earth metal here refers to Be, Mg, Ca, Sr, Ba, and Ra belonging to Group IIA of the periodic table. By setting the content of each atom within the specified range, the effect of inhibiting decomposition of the polyetherimide by pentavalent phosphorus is sufficiently exerted, and the gelation of the polyester can be suppressed. If it is less than 0.02, the film-forming property at the time of making a film is deteriorated, or the surface property is deteriorated by bleeding out when the polyester resin composition is made into a film by adding a large amount of a phosphorus compound. If it exceeds 0.05, the decomposition of the polyetherimide cannot be suppressed, and gelation of the polyester is caused.
0.02 ≦ (M1 / 2 + M2) /P≦0.05 (1)
[In the above formula (1), M1 is the total number of moles of alkali metal atoms in the polyester resin composition, M2 is the total number of moles of alkaline earth metal atoms in the polyester resin composition, and P is phosphorus in the polyester resin composition. Represents the total number of moles of atoms. ]
The method for containing the alkali metal and alkaline earth metal atoms used in the present invention is not particularly limited. However, since it is preferably contained as a catalyst or an additive during the production of the polyester, lithium acetate is used as the alkali metal. As the earth metal, it is preferable to use magnesium acetate.

  The polyester resin composition of the present invention preferably contains 5 to 50 ppm of manganese atoms, more preferably 10 to 40 ppm, and still more preferably 15 to 30 ppm, from the viewpoint of suppressing the gelation of the polyester. By making the amount of manganese atoms within a specified range, it is possible to suppress the degradation of polyetherimide and the gelation of polyester. Although it does not specifically limit as a method to contain a manganese atom, It is preferable to add as a catalyst or an additive at the time of manufacture of polyester.

  Next, although the manufacturing method of polyester of this invention is demonstrated in detail, it is not limited to this. Here, polyethylene terephthalate is used as the polyester.

  First, bis-β-hydroxyethyl terephthalate (BHT) is obtained by esterifying terephthalic acid and ethylene glycol or by transesterifying dimethyl terephthalate and ethylene glycol. In the case of transesterification, manganese acetate tetrahydrate is added as a transesterification catalyst. Next, this BHT is transferred to a polymerization tank, and a conventionally known polymerization catalyst such as antimony, germanium, or titanium compound is added as a polymerization catalyst, and the temperature in the apparatus is slowly heated to 280 ° C., and the pressure is reduced from normal pressure to 133 Pa or less. . As the polymerization reaction proceeds, the viscosity of the reaction product increases. When the predetermined stirring torque is reached, the reaction is terminated, and the polyester is discharged from the polymerization apparatus into a water tank. The discharged polyester is quenched in a water tank and pelletized with a cutter.

  In order to increase the intrinsic viscosity of the obtained polyester, solid phase polymerization may be further performed. In the case of solid phase polymerization, the pelletized polyester is pre-crystallized at a temperature of 180 ° C. or less, and then solid phase polymerization is performed at 190 to 250 ° C. under reduced pressure of about 1 mmHg for 10 to 50 hours. As long as the effect of the present invention is not hindered, the polyester is known in the art using inert particles and various additives such as end-capping agents such as epoxy compounds, ultraviolet absorbers, antioxidants, antistatic agents, and surface active agents. An agent, a pigment, a fluorescent brightening agent, and the like may be appropriately contained as necessary.

  Next, the polyester pellets and the polyetherimide pellets are mixed at a predetermined ratio, vacuum-dried at 180 ° C. for 3 hours or more, and then supplied to a melt extruder heated to 270 ° C. to 300 ° C. At the same time, a pentavalent phosphorus compound in an amount of 820 to 2000 ppm as a phosphorus element is supplied to the polyester resin composition while being measured with a measuring instrument, and melt-extruded to obtain a polyester resin composition. The residence time at this time is preferably 30 to 600 seconds, more preferably 60 to 300 seconds.

  Specific examples of the method for producing a magnetic recording medium film of the present invention will be described in detail, but the present invention is not limited to the following description.

  The obtained polyester resin composition pellets mainly composed of polyester and polyetherimide are vacuum-dried at 180 ° C. for 3 hours or more, and then in a nitrogen stream or under vacuum so that the intrinsic viscosity does not decrease. It is supplied to an extruder heated at 0 ° C., passed through a fiber sintered stainless metal filter, extruded from a slit-shaped die, and cooled while applying an electrostatic charge to a cast drum to obtain an unstretched film. At this time, the polyester resin composition of the present invention and polyethylene terephthalate may be mixed at a predetermined ratio, dried, and supplied to the extruder.

  The unstretched film can then be biaxially stretched and biaxially oriented. As the stretching method, a sequential biaxial stretching method or a simultaneous biaxial stretching method can be adopted.

  In the case of stretching by sequential biaxial stretching, the obtained unstretched film is contacted on a roll group heated to (glass transition temperature Tg-30 ° C.) or more and (glass transition temperature Tg + 50 ° C.) or less of the polyester composition. The film was warmed and stretched 1.1 to 4.0 times in the longitudinal direction, and after cooling this, the end of the film was bitten into a tenter clip and the polyester composition (glass transition temperature Tg + 5 ° C. in the width direction). ) As described above, the polyester composition film is stretched 1.1 to 4.0 times in a temperature atmosphere of (glass transition temperature Tg + 50 ° C.) or less and biaxially oriented. When the biaxially oriented film after stretching is further heat-treated at a temperature in the range of Tg + 50 ° C. to Tg + 150 ° C., the dimensional stability is improved.

  The biaxially oriented film (support for magnetic recording medium) obtained as described above is slit, for example, into a width of 0.1 to 3 m, and conveyed at a speed of 20 to 300 m / min and a tension of 50 to 300 N / m. A magnetic paint and a non-magnetic paint are applied to one surface (A surface) with an extrusion coater. A magnetic paint is applied to the upper layer with a thickness of 0.1 to 0.3 μm, and a nonmagnetic paint is applied to the lower layer with a thickness of 0.5 to 1.5 μm. Thereafter, the support coated with the magnetic coating material and the nonmagnetic coating material is magnetically oriented and dried at a temperature of 80 to 130 ° C.

Next, a back coat is applied to the opposite surface (B surface) with a thickness of 0.3 to 0.8 μm, and after calendar treatment, it is wound up. The calendering is performed using a small test calender (steel / nylon roll, 5 stages) at a temperature of 70 to 120 ° C. and a linear pressure of 0.5 to 5 kN / cm. Thereafter, the film is aged at 60 to 80 ° C. for 24 to 72 hours, slit to a width of 1/2 inch (1.27 cm), and a pancake is produced. Next, a specific length from this pancake is incorporated into a cassette to obtain a cassette tape type magnetic recording medium.
Examples of the composition of the magnetic paint include the following compositions.
Hereinafter, when “part” is simply described, it means “part by mass”.

[Magnetic layer forming coating solution]
Barium ferrite magnetic powder 100 parts [plate diameter: 20.5 nm, plate thickness: 7.6 nm, plate ratio: 2.7, Hc: 191 kA / m (≈2400 Oe) saturation magnetization: 44 Am2 / kg, BET specific surface area: 60 m2 / G]
12 parts polyurethane resin Mass average molecular weight 10,000
Sulfonic acid functional group 0.5 meq / g
α-Alumina HIT60 (Sumitomo Chemical Co., Ltd.) 8 parts Carbon black # 55 (Asahi Carbon Co., Ltd.) Particle size 0.015 μm 0.5 parts Stearic acid 0.5 parts Butyl stearate 2 parts Methyl ethyl ketone 180 parts Cyclohexanone 100 parts Magnetic layer forming coating solution]
Nonmagnetic powder α iron oxide 100 parts Average major axis length 0.09μm, specific surface area by BET method 50m2 / g
pH 7
DBP oil absorption 27-38ml / 100g
Surface treatment layer Al2O3 8% by mass
Carbon black 25 parts CONDUCTEX SC-U (manufactured by Colombian Carbon)
Vinyl chloride copolymer MR104 (manufactured by Nippon Zeon) 13 parts Polyurethane resin UR8200 (manufactured by Toyobo Co., Ltd.) 5 parts Phenylphosphonic acid 3.5 parts Butyl stearate Magnetic recording media are, for example, data recording applications, specifically computers. It can be suitably used for data backup applications (for example, linear recording system recording media (linear magnetic recording media such as LTO4 and LTO5)) and digital image recording applications such as video.

The present invention will be described more specifically with reference to the following examples.
In addition, the measuring method of a physical property and the evaluation method of an effect were performed in accordance with the following method.

(1) Content of metal atom in polyester resin composition Using a fluorescent X-ray elemental analyzer (manufactured by Horiba, Ltd., MESA-500W type), the fluorescent X-ray intensity for each atom was determined and prepared in advance. It was determined from a calibration curve.

(2) Content of pentavalent phosphorus atom in polyester resin composition Using CMX-300 manufactured by Chemicals, solid ³¹ P-NMR measurement was performed at room temperature. As chemical shift standards, 85 wt% phosphoric acid aqueous solution (external standard 0.0 ppm) and (NH ₄ ) ₂ HPO ₄ (external standard 1.33 ppm) were used. About the obtained spectral peak, the total I ₃ of the peak value attributed to trivalent phosphorus (corresponding to the position of about 1100 to 160 ppm) and the peak value attributed to pentavalent phosphorus (about 50 ppm or less, from trivalent value) be used total I calculated ₅ as a ratio, the content P of the phosphorus atom as determined by the (1) equivalent) to the low ppm, calculated content P ₅ of pentavalent phosphorus atom, by the following formula did. The spinning sideband was added to the integrated value of the main peak of each peak.
P ₅ = P × I ₅ / (I ₃ + I ₅ )
(3) Gelation rate of polyester resin composition 1 g of the polyester resin composition was freeze-pulverized to form a powder having a diameter of 300 μm or less and vacuum-dried. The sample is heat treated in an oven at 300 ° C. for 2.5 hours in the atmosphere. This is dissolved in 50 ml of orthochlorophenol (OCP) by heating at a temperature of 80 to 150 ° C. for 0.5 hour. Subsequently, it is filtered through a Buchner type glass filter (maximum pore size 20-30 μm), washed and vacuum dried. The weight of the OCP insoluble matter remaining on the filter is calculated from the increase in the weight of the filter before and after filtration, and the weight fraction with respect to the weight of the OCP insoluble polyester resin composition (1 g) is obtained. did.

(4) Film forming property of polyester resin composition 99 parts by weight of a polyester resin composition and 1 part by weight of silica having an average particle size of 0.06 μm are mixed, and the mixture is melt-kneaded to prepare a silica-containing polyester resin composition. did. Next, 80 parts by weight of the polyester resin composition and 20 parts by weight of the silica-containing polyester resin composition were mixed, these mixtures were dried under reduced pressure at 180 ° C. for 3 hours, and supplied to an extruder E heated to 300 ° C. Introduced into die die. Next, a melt of the polyester resin composition and the silica-containing polyester resin composition is extruded into a sheet from the inside of the T die die to form a molten single layer sheet, and the molten single layer sheet is charged into a cast drum having a surface temperature of 25 ° C. While being applied, the film was closely cooled and solidified to prepare an unstretched film, and the film forming property was judged according to the following criteria.
○: A film was successfully created.
(Triangle | delta): Although the adhesiveness fall to a cast drum was seen, there was no problem in preparation of a film.
X: Adhesion to the cast drum was poor, making it difficult to produce a film.

(5) Presence or absence of bleed-out of phosphorus compound on film surface The surface state of the unstretched film prepared by the above method was visually confirmed and evaluated according to the following criteria.
○: Bleed material is not observed on the film surface.
X: Bleed material is observed on the film surface.

Example 1
An esterification reaction product (low polymer) of 86 parts by weight of terephthalic acid and 39 parts by weight of ethylene glycol was melted at 240 ° C. in an ester exchange reaction tank, and 86 parts by weight of terephthalic acid and 39 parts by weight of ethylene glycol were added thereto. The esterification reaction is continued while stirring at 250 ° C., and a reaction product corresponding to 86 parts by weight of terephthalic acid is converted from the esterification reaction product in which the water distillation amount reaches 97% or more of the theoretical distillation amount. It moved to. Subsequently, 0.03 parts by weight of antimony trioxide, 30 ppm of triethylphosphonoacetate as a phosphorus atomic weight with respect to polyester, 6 ppm of lithium acetate dihydrate as a lithium atomic weight with respect to polyester, and magnesium acetate tetrahydrate as polyester The magnesium atom weight was 60 ppm, and the manganese acetate tetrahydrate was weighed to 40 ppm as the manganese atom weight with respect to the polyester, and added to the polycondensation reaction tank to which the esterification reaction product had been transferred. Then, while stirring the esterification reaction product, the reaction system was gradually heated from 250 ° C. to 290 ° C. and the pressure was reduced to 0.1 kPa. When the predetermined stirring torque was reached, the reaction system was purged with nitrogen to return to normal pressure, the polycondensation reaction was stopped, discharged into cold water in a strand form, and immediately cut to obtain a polyester with an intrinsic viscosity of 0.6.

  Next, 50 parts by weight of polyester pellets obtained by the above method and 50 parts by weight of polyetherimide ("ULTEM 1010-1000" (registered trademark) manufactured by SABIC Innovative Plastics) having an Mw of 32000 are used. , Triethylphosphonoacetate in an amount of 1500 ppm as a polyester resin composition is supplied to a co-rotating twin-screw kneading extruder (Toshiba Machine Co., Ltd. TEM-35B), extrusion temperature of 300 ° C., shear rate of 150 seconds-1, The mixture was kneaded and discharged under conditions of residence time of 3.5 minutes, cooled with water, pelletized and molded into pellets.

  The composition and production conditions of the polyester resin composition are shown in Table 1, and the evaluation results of the obtained polyester resin composition are shown in Table 2. The polyester resin composition of the present invention has a gelation rate as low as 0.1%, has good film-forming properties during film production, and no bleed material was observed on the film surface.

Examples 2 and 3
A polyester resin composition was obtained in the same manner as in Example 1 except that the ratio of polyester and polyetherimide was changed. The results are shown in Tables 1 and 2. In Example 2, the gelation rate and film-forming property of the polyester resin composition were good, and no bleed on the film surface was observed. In Example 3, due to the reduction of the content of alkali metal and alkaline earth metal due to the reduction of the polyester ratio in the polyester resin composition, there was a slight decrease in adhesion to the cast drum during film formation. However, the level was satisfactory and the gelation rate and film forming property of the polyester resin composition were good.

Example 4
A polyester resin composition was obtained in the same manner as in Example 1 except that the pentavalent phosphorus compound was changed to trimethyl phosphate. The results are shown in Tables 1 and 2. In Example 4, the gelation rate and film forming property of the polyester resin composition were good, and no bleed on the film surface was observed.

Examples 5 and 6
A polyester resin composition was obtained in the same manner as in Example 1 except that the phosphorus atom content was changed. The results are shown in Tables 1 and 2. In Example 5, although the gelation rate increased by reducing the amount of phosphorus atoms, it was at a satisfactory level, the film-forming property was good, and no bleed material on the film surface was observed. In Example 6, the adhesion level to the cast drum during film formation was slightly reduced due to an increase in the amount of phosphorus atoms, but this was a problem-free level. The gelation rate and film forming property of the polyester resin composition Was good.

Examples 7 to 10 (Example 10 is replaced with a reference example)
A polyester resin composition was obtained in the same manner as in Example 1 except that the contents of lithium atoms and magnesium atoms were changed. The results are shown in Tables 1 and 2. In Examples 7, 8 and 10, the gelation rate and film forming property of the polyester resin composition were good, and no bleed on the film surface was observed. In Example 9, by reducing the content of alkaline earth metal, a slight decrease in adhesion to the cast drum during film formation was observed, but there was no problem, and the polyester resin composition was gelled. The rate and film formability were good.

Examples 11-14
A polyester resin composition was obtained in the same manner as in Example 1 except that the manganese atom content was changed. The results are shown in Tables 1 and 2. In Examples 12 and 14, when the content of manganese atoms is outside the preferred range, an increase in the gelation rate was observed for a while, but it was at a satisfactory level, the film forming property was good, and the film surface No bleed was observed. In Examples 11 and 13, the gelation rate and film forming property of the polyester resin composition were good, and no bleed on the film surface was observed.

Example 15
In the polycondensation reaction of polyester, when the predetermined stirring torque is reached, additional triethylphosphonoacetate is added to the polycondensation reaction tank, and after stirring for 5 minutes, the reaction system is purged with nitrogen and returned to normal pressure for polycondensation. A polyester resin composition was obtained in the same manner as in Example 1 except that the reaction was stopped, discharged into cold water in a strand shape, and immediately cut to obtain a polyester. The results are shown in Tables 1 and 2. In Example 15, by changing the time when triethylphosphonoacetate was added, dispersion was insufficient and a slight increase in gelation rate was observed, but there was no problem and the film-forming property was good. Also, no bleed on the film surface was observed.

Comparative Example 1
A polyester resin composition was obtained in the same manner as in Example 1 except that triethylphosphonoacetate was changed to “ADEKA STAB PEP-36” manufactured by ADEKA, which is a trivalent phosphorus compound. The results are shown in Tables 1 and 2. In Comparative Example 1, since a trivalent phosphorus compound was used instead of a pentavalent phosphorus compound, when a film was formed, a bleed material was observed on the film surface, which was poor.

Comparative Examples 2 and 3
A polyester resin composition was obtained in the same manner as in Example 1 except that the phosphorus atom content was changed. The results are shown in Tables 1 and 2. In Comparative Example 2, since the phosphorus atomic weight was less than the specified range, the gelation rate was increased and was poor. In Comparative Example 3, since the phosphorus atomic weight exceeded the specified range, the adhesion to the cast drum during film formation was poor, and it was difficult to collect the film, and bleed was confirmed on the film surface, which was defective. .

Comparative Examples 4-6
A polyester resin composition was obtained in the same manner as in Example 1 except that the contents of lithium atoms and magnesium atoms were changed. The results are shown in Tables 1 and 2. In Comparative Examples 4 and 5, since the range of the formula (1) was exceeded, an increase in the gelation rate was observed, which was poor. In Comparative Example 6, since it was less than the range of the formula (1), the adhesion to the cast drum during film formation was poor and it was difficult to collect the film.

Claims (3)

A polyester resin composition comprising polyester and polyetherimide as main components, containing 820 to 2000 ppm of pentavalent phosphorus atoms, and the content of alkali metal atoms, alkaline earth metal atoms and phosphorus atoms in the polyester resin composition (A content of alkali metal atoms is 2.4 ppm or more) satisfies the following formula (1), and contains 2 to 60% by weight of the polyetherimide.
0.02 ≦ (M1 / 2 + M2) /P≦0.05 (1)
[In the above formula (1), M1 is the total number of moles of alkali metal atoms in the polyester resin composition , M2 is the total number of moles of alkaline earth metal atoms in the polyester resin composition, and P is phosphorus in the polyester resin composition. Represents the total number of moles of atoms. ]   The polyester resin composition according to claim 1, wherein the polyester resin composition contains 5 to 50 ppm of manganese atoms. The film for magnetic recording media manufactured using the polyester resin composition of Claim 1 or 2.