JPH051211A - Aromatic polyester composition - Google Patents

Abstract

PURPOSE:To obtain an aromatic polyester composition useful for obtaining biaxially oriented films having excellent scratch resistance, running properties, and surface evenness by incorporating specific composite particles. CONSTITUTION:The objective composition contains composite particles composed of inactive particles having a positive zeta-potential in pure water (e.g. Al2O3) and inactive particles having a negative zeta-potential in pure water. The latter particles consist, for example, of an aromatic dicarboxylate (e.g. bis(beta- hydroxyethyl) terephthalate or a low-molecular polymer thereof), an alkali (alkaline earth) metal compound (e.g. lithium acetate), and a phosphorus compound (e.g. trimethyl phosphate or phosphorous acid).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyester composition having excellent running properties and surface flatness when formed into fibers or films. In particular, it relates to a polyester composition capable of producing a biaxially stretched polyester film having improved scratch resistance, running property and surface flatness when the polyester of the present invention is molded as a film.

[0002]

2. Description of the Related Art Polyester films typified by polyethylene terephthalate and polyethylene naphthalate have excellent mechanical properties, weather resistance, electrical insulation and chemical resistance, and are therefore magnetic tape films and capacitor films. Widely used for photographic film, etc. In order to improve the handleability in the manufacturing process, and further the slipperiness and surface characteristics of the final product, these polyester films are usually used with a method of containing fine particles in the polyester to form appropriate irregularities on the film surface. There is.

As such fine particle-containing polyester, a polyester composition containing inert inorganic particles such as silicon oxide, titanium dioxide, calcium carbonate, talc and clay, an alkali metal compound or alkaline earth added at the time of synthesis of polyester Precipitated particles having a metal compound as a component of a phosphorus compound, a polyester composition produced by a polycondensation reaction system, a polyester containing the inert inorganic particles of Item, and the precipitated particles of Item. A polyester composition in which the contained polyester is appropriately blended has been proposed.

However, in order to achieve fine homogenization of the particles added in the above composition, in the case of natural inorganic particles, it is necessary to undergo steps such as pulverization and classification, and in the case of synthetic inorganic particles, it is necessary to synthesize them. Since the particle diameter tends to vary depending on the conditions at the time, it was necessary to perform dispersion, classification and the like. Further, when the inert inorganic particles thus obtained are added to the polycondensation reaction system, the particles are likely to aggregate,
It was always difficult to obtain a uniform particle size. Furthermore, since these inert inorganic particles have an unfavorable affinity with the base polyester, the inert inorganic particles are detached from the film when formed into a film and then run as a magnetic recording tape, for example. It had a serious problem of being easy.

On the other hand, in the polyester composition obtained by precipitating the fine particles in a reaction system, the structure of the precipitated particles is similar to that of the polyester constituting the base material.
Although it has a good affinity for polyester, it has the drawback that the particle size of the precipitated particles tends to vary due to slight variations in the reaction system.

Further, as the above-mentioned method, in order to improve the slipperiness and surface characteristics of the film, JP-A-55-204 has been used.
No. 96 discloses an example of a combination of inorganic particles having an average particle diameter of 1.0 to 10 μm and precipitated particles precipitated in a polyester reaction system. These methods were merely for controlling unevenness of the film surface or preventing white powder generated when the film was handled by combining particles having different characteristics, but at present, further surface flatness is required. , I am not satisfied with the one obtained by this method. Further, in JP-A-59-204617, during the polycondensation reaction, particles having an alkali metal or alkaline earth metal as a part of the constituents are precipitated in the presence of a particulate matter having a specific surface area of 5 m ² / g or more. A method for improving the resistance to wear and abrasion is disclosed. By this method, it is possible to obtain a polyester containing fine particles to some extent, the biaxially stretched polyester film using the polyester is a manufacturing step or a processing step, or when the product film is used as a magnetic tape, The film is easily scratched during recording and playback. Further, in JP-A-2-24823, inactive particles precipitated in a polyester manufacturing process are used in combination with inorganic particles having a Mohs hardness of 6 or more to prevent scratches and abrasion powder when the polyester is used as a film. Attempts to control the outbreak have been disclosed. However, what is disclosed in the present invention is that only two or more kinds of particles coexist, and the effect of improving the scratch resistance is insufficient, and the inorganic particles are required to improve the scratch resistance. Needs to be contained in a large amount. The inclusion of a large amount of inorganic particles has a drawback that the thermal stability of the polyester is lowered and gel-like foreign matter is easily generated in the obtained film.

Particularly in recent years, in magnetic tape applications, high recording density and high speed running resistance have been remarkably demanded. In addition to making the surface unevenness of the film uniform, scratch resistance of the film when running at high speed is improved. Improvement is required. However, in the polyester composition obtained by the conventionally known method, the added inert inorganic particles have insufficient affinity with the base polyester, or the obtained film has insufficient uniformity of surface irregularities. Moreover, the scratch resistance was unsatisfactory.

[0008]

DISCLOSURE OF THE INVENTION The present invention provides a polyester composition which has good scratch resistance even when running at high speed and which can reproducibly produce a fiber or film having excellent surface flatness and slipperiness. The purpose is to provide.

[0009]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide inert particles and ζ-in which the ζ-potential is a positive charge in pure water.
It can be achieved by an aromatic polyester composition containing composite particles composed of inert particles having a negative charge.

The inert particles in the present invention are particles which are substantially insoluble in polyester.

Further, the ζ-potential in the present invention is a value measured by an ordinary electrophoretic method by adding inert particles to pure water to form a diluted slurry, and specifically, the inert particles are purified water. After being evenly dispersed in the LA, PENKEM LA
The ζ-potential was measured using a SERZEE ^™ Model 501. The concentration of the inert particles is not directly related to the ζ-potential, but when the inert particles are dispersed in pure water, it is usually preferable that the concentration of the inert particles is 1 to 100 ppm with respect to the pure water.

The aromatic polyester (hereinafter simply referred to as polyester) in the present invention means terephthalic acid, 2,6
-Naphthalenedicarboxylic acid, diphenyldicarboxylic acid,
A polyester obtained from an aromatic dicarboxylic acid component such as isophthalic acid and a glycol component such as ethylene glycol, butanediol, and cyclohexane dimethanol, specifically, polyethylene terephthalate and poly Examples thereof include butylene terephthalate and polyethylene naphthalate. These polyesters may be homopolymers or copolymers. It is also possible to use one or more of the above-mentioned dicarboxylic acid component and diol component. Further, it is possible to use polyalkylene glycol such as polyethylene glycol and polybutylene glycol, aliphatic dicarboxylic acid such as adipic acid and sebacic acid, 5-sodium sulfoisophthalic acid, and hydroxyethoxybenzoic acid. it can.

The inert particles whose ζ-potential is positive charge in the present invention are those whose ζ-potential shows positive charge in the above-mentioned measuring method. In particular, the ζ-potential is +3
If it is 0 or more, and +50 or more, it is easy to combine with the inert particles having negatively charged ζ-potential, and when it is formed into a fiber or film, many fine protrusions are generated on the surface,
It is preferable because it has excellent surface flatness, slipperiness, and scratch resistance.

As the inactive particles having a positive charge of ζ-potential, magnesium oxide, calcium oxide, aluminum oxide, zirconium oxide, zinc oxide and the like, and composite oxides thereof, and at least one of barium oxide and calcium carbonate are used. I can give you. Among these compounds, aluminum oxide, zirconium oxide, and magnesium oxide are particularly preferable because they easily generate composite particles.

In the present invention, the ζ-potential is positive charge.
The average primary particle diameter of the inert particles of di is 0.01 to
It is preferably 1.0 μm. Further, the content is preferably 0.001 to 3.0% by weight, more preferably 0.01 to 1.0% by weight, based on the polyester.
When the average primary particle diameter and the content of the inert particles are in the above-mentioned range, the inert particles themselves are less likely to aggregate and the composite particles are easily produced, so that the surface flatness, the slipperiness and the scratch resistance are improved. Therefore, it is preferable.

In the present invention, the ζ-potential is a negative char.
The inert particles which are the particles are particles whose ζ-potential exhibits a negative charge in the above-mentioned measuring method. In particular, if the ζ-potential is -30 or less, it is easy to complex with inert particles having a positive ζ-potential, and when it is formed into a fiber or film, many fine protrusions are generated on the surface, so that the surface flatness, It is preferable because it is excellent in slipperiness and scratch resistance.

Examples of the inactive particles having a negative charge of ζ-potential include inactive particles comprising an aromatic dicarboxylate, at least one of an alkali metal compound or an alkaline earth metal compound, and a phosphorus compound. ..

In the present invention, the number of moles of the alkali metal compound (A) and the alkaline earth metal compound (M) contained in the inert particles having a negative charge of ζ-potential,
The ratio (M + 0.5A) / P of the number of moles (P) of the phosphorus compound is preferably 0.5 to 5.0 because the particle diameter of the inert particles becomes uniform and fine. The content of these metal compounds and phosphorus compounds is 0.00 in terms of atoms with respect to polyester.
It is preferably 5 to 3.0% by weight.

As the alkali metal compound or alkaline earth metal compound, a glycol-soluble metal compound soluble in the polycondensation reaction system can be preferably used. Examples of such glycol-soluble alkali metal compounds and alkaline earth metal compounds include hydrides, alcoholates, halides, hydroxides, carbonates, carboxylates and sulfates. Specifically, lithium acetate, lithium chloride,
Examples thereof include lithium hydroxide, sodium chloride, potassium acetate, calcium acetate, magnesium acetate, calcium chloride and calcium glycolate, and two or more kinds may be used.

The phosphorus compound may be either trivalent or pentavalent. Specifically, phosphoric acid, phosphorous acid, or their methyl esters, ethyl esters, phenyl esters, and their half esters and phosphonic acids,
A group consisting of phosphinic acid or an ester thereof can be mentioned, and it is particularly preferable to use a trivalent phosphorus compound and a pentavalent phosphorus compound in combination because the composite particles become fine and uniform.

The composite particles in the present invention are ζ-in pure water.
It is composed of inert particles having a positive charge and ζ-inert particles having a negative charge. When a polyester composition containing such composite particles is formed into a film or a fiber, many fine protrusions are formed. As a result, the film or fiber has excellent surface flatness, the friction characteristics during running can be improved, and the scratch resistance can be remarkably improved.

In the present invention, the ζ-potential is positive charge.
The average particle diameter of the composite particles composed of the inert particles having a negative charge and the inert particles having a negative charge of ζ-potential is:
It is preferably 0.01 to 10 μm, and 0.1 to
More preferably, it is 5.0 μm. The preferable content of the composite particles is 0.005 to polyester.
It is 5.0% by weight, more preferably 0.01 to 2.0% by weight, and most preferably 0.1 to 1.0% by weight. When the average particle size and the content of the composite particles are within the above ranges, the surface flatness, slipperiness and scratch resistance of the biaxially stretched film are remarkably improved.

The composite particles of the present invention may be synthesized in the polyester polycondensation reaction system, or may be synthesized outside the polyester polycondensation reaction system and then added to the polyester production stage. Even in the case of, by allowing two kinds of inert particles having different charges on the particle surface to coexist before the completion of the polycondensation reaction of polyester, Can be generated. The preferable coexistence time is a stage before the intrinsic viscosity of the polyester reaches 0.3.

When a polyester containing such composite particles is used as a biaxially stretched film, the reason why the surface flatness, slipperiness and scratch resistance are improved is not clear, but the composite particles are more effective than polyester. It is thought to have some effect. In the present invention, inactive particles such as silicon dioxide, titanium oxide, talc, kaolin, etc. having a negative ζ-potential are used instead of inert particles having a positive ζ-potential such as magnesium oxide. If it is, the complex particles cannot be formed with the inactive particles whose ζ-potential is a negative charge. Further, when a polyester containing two kinds of inactive particles having a ζ-potential of negative charge is used as a biaxially stretched film, surface flatness, slipperiness and scratch resistance are not improved, It merely obtains the bimodal surface protrusions formed by the inert particles having different average particle diameters. Also, ζ
-Even when inert particles having different potentials are used, composite particles are not formed when they are coexisted after the polyester polycondensation reaction is completed. In the case where the polyester in which the inert particles having different ζ-potentials simply coexist in this way is used as a biaxially stretched film, surface flatness, slipperiness and scratch resistance are not improved.

A typical method for producing a polyester containing the most preferable composite particles is polyethylene terephthalate.
Will be described as an example.

By subjecting terephthalic acid or its lower alkyl ester and ethylene glycol to an esterification reaction or a transesterification reaction, bis- (β-hydroxyethyl) terephthalate and its low polymer (hereinafter referred to as BHT)
I get). In the case of the esterification reaction method, a catalyst may be added or no catalyst may be used. In the case of the transesterification reaction method, known reaction catalysts such as alkali metal compounds, alkaline earth metal compounds, zinc compounds and manganese compounds can be used. BHT thus obtained
After adding a phosphorus compound and inert particles positively charged with ζ-potential, polyethylene terephthalate (hereinafter referred to as PET) is obtained in the presence of a polycondensation reaction catalyst. The above-mentioned alkali metal compound and alkaline earth metal compound can be added again after the transesterification reaction is substantially completed. In this case, the inert particles whose ζ-potential is positively charged are It is preferable that at least one of the alkali metal compound and the alkaline earth metal compound and the phosphorus compound are allowed to be present before the start of the precipitation of the particles which are a part of the constituents. In addition, inactive particles with a positive ζ-potential exist before the addition of alkali metal compounds, alkaline earth metal compounds, and phosphorus compounds that are added after the esterification reaction or transesterification reaction is completed. It is particularly preferable to allow it.

The method of adding the inert particles having a positive ζ-potential to the reaction system is preferably in the form of a glycol slurry. In preparing the slurry, for example, the polycondensation reaction system after the dispersion treatment by the method proposed in Japanese Patent Application Laid-Open No. 61-23623, the wet medium method such as known sand grinder, and further the dispersion treatment such as ultrasonic wave is performed. Is preferably added to. In addition to these mechanical dispersion treatments, a treatment with a dispersant or a surface treatment agent can be performed, but it is preferable to perform treatment so as not to change the surface charge of the inert particles. Further, it can be added after the classification treatment with a super decanter or the like.

As another method, inactive particles composed of a BHT component, at least one of an alkali metal compound, an alkaline earth metal compound and a phosphorus compound, and an inert particle having a positive ζ-potential. A method may be mentioned in which composite particles composed of particles are synthesized in advance outside the polycondensation reaction system (hereinafter referred to as synthetic particles) and then added to the reaction system before the polycondensation reaction of PET is completed.

An example of a method for obtaining synthetic particles will be described, but the method is not limited to this method. After adding an alkali metal compound, an alkaline earth metal compound, a phosphorus compound and inactive particles having a positive ζ-potential charge to BHT with a molar ratio of ethylene glycol of 20 to 200, 150 The mixture is reacted at ~ 250 ° C for 1.0 to 10 hours to obtain a slurry of synthetic particles. At this time, the addition amount of each of the alkali metal compound, the alkaline earth metal compound, the phosphorus compound and the inert particles having a positive ζ-potential charge is 0.01 to 1 mol with respect to 1 mol of the acid component. 2.0
Double moles are preferred. Next, the slurry of synthetic particles is subjected to classification and dispersion treatment, and then added to the polyester polycondensation reaction system. Then, PET is obtained in the presence of a polycondensation reaction catalyst.

As the polycondensation catalyst, known catalysts such as glycol-soluble antimony compounds, germanium compounds and titanium compounds can be used.

The polyester composition of the present invention also comprises
To improve the slipperiness of the obtained film, calcium carbonate, titanium oxide, kaolin, silicon dioxide or the like can be added.

When the aromatic polyester composition of the present invention is used as a biaxially stretched polyester film, it may be either a monolayer film or a composite film having at least one surface composed of the aromatic polyester composition of the present invention. Good. In the case of a composite film, it is preferable that the aromatic polyester composition of the present invention has a thickness of 1/5 to 1/50 of the total film thickness, because the uniformity of film projections, slipperiness and scratchability are improved.

[0033]

The present invention will be described in detail below with reference to Examples. The ζ-potential value in the examples is measured in pure water and shown in mV. Moreover, the part in an Example shows a weight part. The measurement of each characteristic value was performed according to the following methods.

A. Intrinsic viscosity of polymer Measured at 25 ° C using o-chlorophenol as a solvent.

B. Average particle size of particles Before addition to the reaction system, the average particle size was measured using a scanning electron microscope in a diluted slurry state. The average particle size of the two types of particles in the polymer composition was measured using a scanning electron microscope after the polymer composition was formed into a film and the film was sliced to a thickness of 1 μm or less.

C. Particle Content in Polymer Composition To 300 g of the polyester composition, 2.7 kg of o-chlorophenol was added, and the polymer was dissolved with stirring at 100 ° C. for 1 hour. Next, a rotor ultra-centrifuge 40P type manufactured by Hitachi, Ltd. was equipped with a rotor RP30, and 30 cc of the above-mentioned solution was injected into each cell, and then gradually increased to 30,000
Set to 0 rpm. Separation of particles is completed 60 minutes after reaching 30,000 rpm.

Next, the supernatant is removed and separated particles are collected. After o-chlorophenol at room temperature is added to the collected particles and suspended uniformly, ultracentrifugation operation is performed.

This operation was carried out by using a differential scanning calorimeter (DSC) to analyze the separated particles described below, and melted the particles corresponding to the polymer.
Repeat until no marks are detected.

The separated particles thus obtained were vacuum-dried at 120 ° C. for 16 hours and then weighed to obtain the content of the particles in the polymer composition.

D. Evaluation of Composite State of Particles A polyester composition I containing inert particles having a ζ-potential of positive charge and inert particles having a ζ-potential of negative charge is obtained. Separately, ζ-potential is negative char
A polyester composition II is obtained which does not contain the inert particles which are di, but which contains the same amount of the inert particles which are the same as in the polyester composition I. After forming a film from each of the polyester composition I and the polyester composition II, the obtained film was sliced to a thickness of 1 μm or less, and an inactive particle having a ζ-potential of plus charge using a scanning electron microscope. Observe the numbers N _I and N _II of. The composite rate is calculated by the following formula. Composite rate (%) = (N _II −N _I ) / N _II × 100 The composite state of particles was evaluated according to the following criteria. Composite rate 70% or more A class Composite rate 50 to 70% B class Composite rate less than 50% C class A class and B class were used as composite particles.

E. Average Surface Roughness (Ra) According to the method specified in JIS-B-0601, the surface roughness was measured with a stylus surface roughness meter at a cutoff of 0.08 mm and a measurement length of 4 mm, and expressed in Ra (nm). F. Roughness parameter P ₁₀ Optical interference type 3D surface shape analyzer (TOP made by WYKO
O-3D, objective lens; 20 to 100 times, using high resolution camera) is used to construct a film surface protrusion image on an image processing device. 1 from the highest protrusion in this surface protrusion image
The difference between the average of 0 points and the average of 10 points from the lowest dent is P
_{It was set to 10} (nm). Such measurement was performed 20 times and the average value was taken. The smaller the value, the more uniform the projection is,
The thickness of 0 nm or less was accepted.

G. Scratchability evaluation A tape which is slit to 1/2 inch is repeatedly run using a high speed tape running tester (running speed 8
(00m / min, 5 passes). At this time, scratches in the film were arbitrarily observed at 10 locations in the width direction using a microscope, the number of scratches per width was determined, and the following four grades were evaluated and grade 1 and grade 2 were passed. No scratches 1st class 1 to 3 scratches 2nd class 4 to 10 scratches 3rd class 11 or more scratches 4th class

H. Friction coefficient The static friction coefficient was measured using a slip tester according to the ASTM-D-1894B method. The smaller the value, the better the slipperiness.

Example 1 100 parts of dimethyl terephthalate Ethylene glycol 64
And 0.1 part of calcium acetate as a catalyst were subjected to transesterification reaction by a conventional method. To the reaction product, 0.2 part of δ type A1 ₂ O ₃ (ζ-potential +70) having an average particle diameter of 20 mμ, which was made into a slurry of 8% ethylene glycol, was added. After 10 minutes, 0.17 part of lithium acetate and 0.03 part of antimony trioxide were added. After further 10 minutes, 0.15 parts of trimethyl phosphate and 0.02 part of phosphorous acid were added, and then transferred to a polymerization reaction tank to carry out polycondensation reaction by an ordinary method to obtain a polymer having an intrinsic viscosity of 0.614. It was The amount of separated particles in the obtained polymer was 0.69%, and the average particle size was 0.
It was 3μ and the composite state was class A. Next, the obtained polymer was extruded at 290 ° C. with an extruder to melt the sheet, and then rapidly cooled with a canceling drum to obtain an unstretched sheet. Subsequently, the film was stretched 3.5 times in the longitudinal and transverse directions at 98 ° C. and heat set at 230 ° C. for 3 seconds to obtain a 15 μ biaxially stretched film. Film properties are shown in Table 3, RA18, the friction coefficient 1.0, P ₁₀ 141, had a good biaxially oriented film in the scratch resistance primary.

Examples 2 to 6 Examples other than the case where the δ-type Al ₂ O ₃ used in Example 1 was replaced by the addition of inert inorganic particles having a positive ζ-potential as shown in Table 1. Polycondensation reaction and film formation were performed in exactly the same manner as in 1. The results are shown in Tables 2 and 3. The biaxially stretched films using the polymer containing the composite particles all showed good results.

Comparative Examples 1 to 3 Comparative Examples 1 to 3 were carried out except that inactive inorganic particles having a negative ζ-potential charge shown in Table 1 were added instead of the δ type Al ₂ O ₃ used in Example 1. A polymer was obtained in exactly the same manner as in Example 1. The particles in the polymer were uncomplexed. The film properties are shown in Table 3. If it is not a composite particle, Ra,
The biaxially stretched film was not preferable in terms of slipperiness, scratch resistance and P ₁₀ . The results are shown in Tables 2 and 3.

[0047]

[Table 1]

[0048]

[Table 2]

[0049]

[Table 3]

Comparative Example 4 Except that δ type Al ₂ O ₃ was not added in Example 1,
In exactly the same manner as in Example 1, the ζ-potential becomes negative.
A polymer having an intrinsic viscosity of 0.614 was obtained (Polymer A) containing the inactive particles (ζ-potential -60) that had been subjected to diversion. The amount of separated particles was 0.55% by weight, and the average particle size was 3.0μ. Separately, a transesterification reaction was carried out by a conventional method using 100 parts of dimethyl terephthalate, 64 parts of ethylene glycol, 0.1 part of magnesium acetate and 0.03 part of antimony trioxide as catalysts. 8 g of ethylene glycol was added to the reaction product.
% Slurry with δ type Al ₂ O ₃ having an average particle size of 20 mμ
2.0 parts of (ζ-potential + 70) was added. Then, after adding 0.04 part of trimethylphosphate, the reaction mixture was transferred to a polycondensation reaction tank and a polycondensation reaction was carried out by an ordinary method to obtain an intrinsic viscosity of 0.
618 polymers were obtained (Polymer B). In the polymer,
Particles other than Al ₂ O ₃ were substantially absent. Next, 90 parts of polymer A and 10 parts of polymer B were mixed, and then a biaxially stretched polyester film was obtained in exactly the same manner as in Example 1. The particles in the obtained film were not composited. Film properties Ra23, scratch resistance secondary friction coefficient 1.0, was biaxially stretched film uniformity is unsatisfactory for are surface protrusions at P ₁₀ 309.

Comparative Examples 5-6 Biaxially stretched polyester films were obtained in exactly the same manner as in Example 1, except that only the polymer A of Comparative Example 4 was used. The film characteristics are Ra28, scratch resistance grade 4, friction coefficient of 0.
7, P ₁₀ 325, and the film was a biaxially stretched film with unsatisfactory uniformity of surface protrusions and scratch resistance.

A biaxially stretched polyester film was obtained in exactly the same manner as in Example 1, except that only the polymer B of Comparative Example 4 was used. The film characteristics were Ra10, scratch resistance grade 1, and friction coefficient of 4.8, and although the surface flatness and scratch resistance were excellent, the slipperiness of the film was unfavorable.

Example 7 Transesterification was carried out by a conventional method using 100 parts of dimethyl 2,6-naphthalenedicarboxylate as a catalyst and 50 parts of ethylene glycol as a catalyst and 0.10 part of calcium acetate as a catalyst. The reaction product was δ-type Al ₂ O ₃ (ζ-potential +7 with 8% slurry in ethylene glycol and average particle diameter of 20 mμ).
0.2) of 0) was added. After 10 minutes, 0.25 part of lithium acetate, 0.05 of calcium acetate and 0.03 part of antimony trioxide were added. After further 10 minutes, 0.25 part of trimethyl phosphate was added, and then the mixture was transferred to a polycondensation reaction tank and polycondensation reaction was carried out by an ordinary method to obtain an intrinsic viscosity of 0.
614 polymers were obtained. The amount of separated particles in the obtained polymer was 0.76%, the average particle size was 0.4 μ, and the composite state was class A. Then, the obtained polymer was extruded at 290 ° C. with an extruder to melt the sheet, and then rapidly cooled with a casting drum to obtain an unstretched sheet. Subsequently, the film was stretched 4.0 times in the longitudinal and transverse directions at 130 ° C. and heat-set at 230 ° C. for 3 seconds to obtain a 15 μ biaxially stretched film. The film characteristics are as shown in Table 3, Ra22, friction coefficient 0.8, P ₁₀ 16
2. It was a good biaxially stretched film with scratch resistance of the first grade.

Example 8 BHT obtained from EG / TPA (molar ratio 1.15) was melt-stored at 250 ° C. in an esterification reaction can.
86.5 parts TPA, 37.1 parts EG (molar ratio 1.15)
The slurry obtained by kneading was continuously fed for 3.5 hours. The reaction system was maintained at 250 ° C. from the start of feeding,
The esterification reaction was performed, and the produced water was distilled off from the top of the rectification column. After the supply of the slurry was completed, the esterification reaction was continued for another 1.0 hour to obtain BHT having a reaction rate of 98.5%. Next, after transferring 104.8 parts of BHT (corresponding to 100 parts of PET) to the polycondensation reactor, lithium acetate 0.5
Parts, calcium acetate 0.1 parts, antimony trioxide 0.0
3 parts were added. Then 0.25 parts of phosphoric acid was added. Further subsequently, γ-type A having an average particle size of 100 mμ
After adding 0.8 part of l ₂ O ₃ (ζ-potential +65),
Polycondensation reaction was carried out by a conventional method to obtain a polyester having an intrinsic viscosity of 0.612 (Polymer C). The amount of polymer separated particles was 1.8%, the average particle size was 0.6 μm, and the composite state was class A. In addition, BH obtained by completing the esterification reaction in the same manner
After adding 0.02 part of trimethylphosphate to T104 part, 0.06 part of magnesium acetate was added. After a further 15 minutes, 0.01 part of antimony trioxide was added, and then polycondensation reaction was carried out by a conventional method to obtain 0.608 polyester (polymer D). Substantially no particles were present in the polymer.

Next, 20 parts of polymer C and 80 parts of polymer D are used.
After blending the parts, a biaxially stretched polyester film was obtained in exactly the same manner as in Example 1. The film characteristics are Ra24,
Scratch resistance secondary friction coefficient 0.9, was P ₁₀ 178.

Example 9 δA added in Example 1 after the transesterification reaction
Polycondensation reaction and film formation were carried out in exactly the same manner as in Example 1 except that l ₂ O ₃ , lithium acetate, antimony trioxide, trimethylphosphite and phosphorous acid were simultaneously added.
Polymer properties: intrinsic viscosity 0.610, separated particles amount 0.7
2, the particle size was 1.3μ, and the composite state was B grade. Using this polymer, a biaxially stretched film having a thickness of 15 μm was obtained in exactly the same manner as in Example 1. Film properties R a21, scratch resistance secondary friction coefficient 0.9, it was P ₁₀ 163.

[0057]

The polyester composition of the present invention contains composite particles composed of inert particles having a ζ-potential of positive charge and inert particles having a ζ-potential of negative charge. Since the composite particles have excellent affinity with polyester and are fine and uniform, a large number of uniform fine projections can be formed when molded as a fiber or film. In particular, when a biaxially stretched film is used, the composite particles have a good affinity with polyester, so there is little falling off from the polyester.The projections are fine, so when used as a film for magnetic recording media, the electromagnetic conversion characteristics are improved. Excellent Since there are many fine protrusions, there is little friction when processing or using the film, and it has excellent runnability. Even when running the film at high speed, scratches do not easily occur.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location C08J 3/205 CFD 9268-4F 5/18 CFD 9267-4F

Claims (1)

Claim: What is claimed is: 1. A composite particle comprising inactive particles having a ζ-potential of plus charge and inert particles having a ζ-potential of minus charge in pure water. An aromatic polyester composition comprising: