KR20030050789A - Biaxially oriented polyester film for condenser and its producing method - Google Patents

Abstract

PURPOSE: Provided are a biaxially oriented polyester film for condenser, which can exhibit a good workability in process and an excellent progressing property, as well as more excellent electrical property and heat resistance at the same time, and a method for producing the same. CONSTITUTION: The method comprising polycondensing at least one of dicarbonic acid or terephthalate and at least one of glycols to form a resin, and molding the resin into a film, is characterized in that propionic acid derivative represented by formula 1 is added to the finally formed resin so that the resin comprises 0.01-1 wt% of phosphorus atom and 0.01-4.0 wt% of chlorine atom. In the formula 1, R1 is hydrogen, C1-C5 methyl group, substituted or unsubstituted phenyl group, cycloalkyl group, haloalkyl group, haloaryl group(wherein the substituents are C1-C5 alkyl group, metal sulfonate, or C1-C5 amine group, R2 is a substituted ethylene group, R3 is selected from bis-(4-hydroxyphenyl)propane having aryl group containing 1-8 chlorines, bis-(4-hydroxyphenyl)methane having aryl group containing 1-8 chlorines, or bis-(4-hydroxyphenyl)hexachloropropane having aryl group containing 1-8 chlorines).

Description

Biaxially oriented polyester film for condenser and its manufacturing method {Biaxially oriented polyester film for condenser and its producing method}

The present invention relates to a biaxially-cultured polyester film for capacitors, and more particularly, it has excellent reactivity of the film surface as a dielectric for capacitors, and thus has good workability and running performance in the manufacturing process of the capacitors, and particularly excellent heat resistance and withstand voltage when used at high temperatures and pressures. It relates to a biaxially oriented polyester film for capacitors exhibiting the properties and the like and a method of manufacturing the same.

Currently, polyester film is widely used as an industrial base material because of its excellent physical and chemical properties. In particular, biaxially oriented polyethylene terephthalate film has been widely used as a film for capacitors because of excellent planarity, dimensional stability, electrical properties and chemical resistance compared to other films.

On the other hand, in recent years, the light and short reduction of the capacitor element has been progressed, specifically, research and development has been made in the direction to maximize the capacitance by maximizing the surface area per unit volume by thinning the film that serves as a dielectric in the capacitor. In other words, thinning of the film is essential for light and short reduction of the capacitor, and the demand for the thin film is increasing for this purpose. However, as the film becomes thinner, many problems occur in the film manufacturing process, the capacitor manufacturing process, and the condenser properties. Particularly, when the film is insufficiently active, workability in the deposition and cutting process during the capacitor manufacturing process becomes poor. As a result, the resistance to the applied voltage and temperature is reduced, resulting in problems such as deterioration of the characteristics of the capacitor and narrowing of the application range.

Techniques for forming fine protrusions in films by containing inorganic or organic fine particles in films for the purpose of improving such problems (Japanese Patent Laid-Open No. 63-182351, Japanese Patent Laid-Open 63-316419, Japanese Patent Laid-Open 62-259304, Japanese Patent Laid-Open 62-59). 88207), surface protrusions formed by relatively large particles in this case improve the mobility and workability of the film, but non-ideal coarse protrusions can cause breakdown in the vicinity of the protrusions and excessive film-to-film The presence of an air layer can reduce the capacitance of the capacitor. In addition, when the film surface is smoothed using relatively small particles in order to improve the electrical characteristics of the capacitor, the runability and workability are extremely deteriorated in the film manufacturing process and the capacitor manufacturing process, and thus cannot be used. In order to simultaneously improve the workability and electrical properties of the films having the opposite relationship, pretreatment of particles such as grinding or classification is performed to control the size and quantity of particles used in the film and to remove coarse particles contained in the particles. Required.

On the other hand, techniques in which particles are produced by internal precipitation without adding particles from the outside, and techniques in which internal particles are produced by calcium and phosphorus compounds added during a transesterification reaction (Japanese Patent Laid-Open No. 63-281416, Japanese Patent Laid-Open) 62-204926) are known in the art, but in general, when external particles are used, defects that may deteriorate electrical characteristics such as dielectric breakdown voltage of a film for capacitors are caused by voids around particles appearing after stretching the film. Unlike the external particles, the internal particles are excellent in affinity with the polyester and do not produce voids as in the external particles. However, since the internal particles are produced by the bonding of the catalyst and BHT during the polyester polymerization reaction, it is difficult to control the particle size and amount, so that when the size of the particles becomes non-ideally small or the generation rate of the particles becomes low, the film manufacturing process or the condenser It can deteriorate driving and workability in the manufacturing process.

In particular, methods for using both external and internal particles together in films to improve the running, workability and electrical properties of the film (Japanese Patent Laid-Open Nos. 58-222519, 58-65744, 57-162721) In this case, the polyester film thus obtained has good elastic modulus, heat resistance, mechanical strength, and chemical properties, but has a problem that it is difficult to evenly satisfy the running, workability, and electrical properties of the film for capacitors.

On the other hand, the technology development of the film capacitor device to be miniaturized and the physical properties of the film required accordingly, that is, to withstand the improvement of the voltage resistance required per unit thickness and insufficient cooling function against the heat generated in the device. There is an increasing demand for improving the heat resistance of the film, and therefore, conventional techniques, namely, the film manufacturing technology using phosphorous acid alone (Japanese Patent Application 57-162721, Japanese Patent Application 62-259304) and the use of complex phosphorus compounds ( Japanese special element 50-98597 and Japanese special element 63-182351) have reached the technical limit which is difficult to exhibit sufficient withstand voltage and heat resistance characteristics. In particular, it is difficult to obtain sufficiently improved withstand voltage and heat resistance characteristics even when applying a technique of introducing a new phosphorus compound and using an excessive amount (Japanese Patent Laid-Open No. 58-65744, Japanese Patent Laid-Open No. 62-204926) to compensate for the drawbacks of the phosphorous compounds. It is known to be difficult, especially in the case of ultrathin, it is known that the effect is not so great.

The present invention has been made in order to solve the above problems, a good workability in the manufacturing process and having excellent running performance, when the thin film to the capacitor film capacitors that can exhibit more excellent electrical characteristics and heat resistance characteristics It is an object to provide a biaxially oriented polyester film.

The present invention provides a polycondensation reaction for producing a biaxially oriented polyester film through a film forming process such as melting, extrusion molding and stretching process of a resin obtained by polycondensing at least one dicarboxylic acid or terephthalate with at least one glycol. A condenser comprising the step of introducing a propynic acid derivative satisfying the following general formula (1) in the step so that the content of phosphorus in the resin finally obtained, 0.01 to 1% by weight, chlorine atom content 0.01 to 4.0% by weight It relates to the production of a biaxially oriented polyester film.

General formula (1)

(Wherein R ₁ is a phenyl group, a cycloalkyl group, a haloalkyl group, a haloaryl group, with or without hydrogen, methyl, or a substituent having 1 to 5 carbon atoms, and various substituents include 1 to 5 alkyl groups, metal sulfonate groups, And an amine group containing 1 to 6 carbon atoms. R ₂ is an ethylene group having a substituent, and the R ₃ substituent is a bis- (4-hydroxyphenyl) propane containing 1-8 chlorine groups in an aryl group. Selected from bis- (4-hydroxyphenyl) methane containing 1-8 chlorine groups, bis- (4-hydroxyphenyl) hexachloropropane, propanediol containing 1 chlorine group)

Hereinafter, the present invention will be described in detail.

The polyester resin obtained in the present invention is made from aromatic dicarboxylic acids such as terephthalic acid, 2,6-naphthalenedicarboxylic acid, or ester compounds thereof, and glycols such as ethylene glycol as the main starting materials, but contains another third component. can do. Dicarboxylic acid components usable at this time include, for example, isophthalic acid, terephthalic acid, 2,6-naphthalenedicarboxylic acid, phthalic acid, adipic acid, sebacic acid, and the like. Can be. As another starting material, the glycol component is, for example, ethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol, and the like, and one or more of these components may be used. . In the present invention, polyesters having 80% or more of the repeating structural units having an ethylene terephthalate or ethylene-2,6-naphthalate structure are more preferable.

The obtained polyester may include additives such as heat stabilizers, antiblocking agents, antioxidants, antistatic agents and ultraviolet absorbers.

The present invention is to obtain a polyester precursor having a degree of polymerization of 2 to 10 by direct esterification or transesterification of the hydroxy phenylphosphinyl propanoic acid derivative compound of formula (1), and polycondensation thereof with high polymerization degree in the presence of a catalyst. In the polycondensation step, a suitable amount is added such that the content of phosphorus atoms in the final polymer is 0.01 to 1.0% by weight and the content of chlorine atoms is 0.01 to 4.0% by weight, and the specific gravity of the film produced using the same is 1.365 to Disclosed is a polyester film characterized by 1.420, a surface resistance of 10 ¹⁶ to 10 ¹⁴ ohms, a dielectric constant of 3.0 to 3.5, and particularly, a heat resistance grade of the polymer constituting the film.

In the present invention, the first and second components used in the synthesis of polyesters include alkylene glycols having 2 to 6 carbon atoms and terephthalic acid or ester forming derivatives thereof, and the third component isophthalic acid, naphthalene dicarboxylic acid, Aromatic dicarboxylic acids such as diphenyl dicarboxylic acid, diphenyl ether dicarboxylic acid, p-hydroxy benzoic acid, hydroxy ethoxy benzoic acid and the like, and derivatives of which chlorine is substituted in the aryl group of these compounds, or ester-forming derivatives thereof, propane Compounds such as polyols such as diols, chloropropanediol, butanediol, cyclohexanediol, cyclohexane dimethanediol, polyols such as polyethylene glycol and polyglycol glycol may be included.

On the other hand, as the phosphinic acid derivative of the general formula (1), 2-chloro-1,3-propanediol, 3-chloro-1,2 in the γ-carboxy group based on 3- (hydroxyphenylphosphinyl) propanoic acid as a basic skeleton Propanediol, bis- (4-hydroxyphenyl) propane containing 1-8 chlorine groups in aryl groups, bis- (4-hydroxyphenyl) methane, aryl groups containing 1-8 chlorines in aryl groups A substance in which bis- (4-hydroxyphenyl) hexachloropropane containing 1-8 chlorine numbers is substituted to have an ester functional group is used. In this case, when the total content of phosphorus element used is less than 0.01% by weight, it is difficult to achieve sufficient heat resistance and other target properties, that is, electrical characteristics, and conversely, when the total content of phosphorus element exceeds 1% by weight, it is basically required. It is not preferable by adversely affecting mechanical properties such as mechanical strength and heat shrinkage stability of the polyester film to be made.

The timing of the addition of the compound of the general formula (1) used in the present invention is possible at any stage of the polyester polymerization, but in particular any polyester precursor having a polymerization degree of 2 to 10 is produced after the completion of the esterification reaction or the transesterification reaction. It is good to perform in the step of, and then further suitable catalyst is added to the polycondensation reaction to the final polymer. In this case, the polycondensation catalyst to be used includes an antimony compound or an oxide of germanium, an organic acid salt, an alkyl and an aryl compound which are generally used.

In addition, by adding a hydroxy phenyl phosphinyl propanoic acid derivative of the general formula (1), it is also possible to use a method of making a polyester master chip of high concentration, blending it to a predetermined concentration in ordinary polyester and melt extruding it. Do.

The film obtained by the present invention exhibits excellent heat resistance and electrical properties only when the total content of phosphorus element is 0.01% to 1% by weight and the chlorine atom content is 0.01 to 4.0% by weight, if the content of phosphorus element and chlorine element is 0.01% by weight. If less than that, the heat resistance of the film is very poor, and if the content is exceeded, the film is not only fragile but also frequently breaks during stretching, resulting in low productivity. In addition, when the specific gravity is less than 1.365, the thermal deformation of the film is severe and the heat resistance is also poor. When the specific gravity is greater than 1.420, the film is also vulnerable and the productivity is lowered. In particular, the phosphorus content is most preferably in the range of 0.1 to 0.8% by weight, chlorine content of 0.1 to 3.5% by weight and specific gravity of 1.385 to 1.400.

On the other hand, in the present invention, when the film is formed by using the withstand voltage and heat resistance improving polymers prepared as described above, a film having a three-layer (A / B / A structure) structure is advantageous in terms of performance, that is, a layer in the center (B). ) Does not contain external particles, which are the source of factors such as voids and pinholes, which can act as nuclei of defects that deteriorate the electrical properties of the capacitor, so that the electrical properties of the film are improved in another aspect. You will get.

The first component particles used in the layer (A) exhibit good runability when the average particle diameter is 0.5 to 2.0 µm (more preferably, 0.7 to 1.5 µm). If the average particle diameter of the first component particles is less than 0.5 μm, the film may not exhibit sufficient running performance. If the average particle diameter exceeds 2.0 μm, coarse protrusions are formed on the surface of the film to cause breakdown during capacitor manufacturing. can do. The first component particles exhibit the best running property when the content in the film is 0.01 to 0.5% by weight (more preferably 0.05 to 0.3% by weight). When the content of the first component particles in the film is less than 0.01% by weight, the film cannot exhibit sufficient running performance. When the content of the first component particles exceeds 0.5% by weight, the generation rate of voids in the film is increased due to the excessive amount of particles, and particle aggregation occurs to produce a capacitor. It can act as a defect that causes insulation breakdown.

In addition, in order to improve the running and workability of the film and to prevent the breakdown of the film due to the non-ideal coarse projection, an extremely uniform size projection must be formed on the surface of the film, and thus the first component particles added to the layer (A). It is preferable that the relationship between the average particle diameter (d: mu m) and the thickness (t: mu m) of the laminated layer A satisfies the following formula (2).

0.1 ≤ ｔ / d ≤ 5.0 (2)

If the ratio of t / d is less than 0.1, sufficient runability may not be exhibited and wear resistance may deteriorate due to particle fallout during film running, and the resulting powder may act as a defect of causing insulation breakdown and deterioration in capacitance during capacitor manufacturing. In addition, when the ratio of t / d exceeds 5.0, uniform protrusions are not formed on the surface of the film, so that sufficient running performance cannot be exhibited. To improve this, the amount of particles to be added must be increased, and the occurrence rate of voids in the film increases due to excessive particles. Agglomeration may occur, which may act as a defect that causes dielectric breakdown in capacitor manufacturing.

In particular, the runability, workability and electrical properties of the thin film for thin and short reduction of the capacitor are the second component having a smaller size than the first component particles in the layer (A) with an average particle diameter of 0.01 to 0.5 탆 (more preferably 0.01 By adding 0.01 to 0.5% by weight (more preferably, 0.05 to 0.3% by weight) of ultrafine particles of ˜0.1 μm) to form fine protrusions, better characteristics can be obtained. If the average particle diameter of the second component is less than 0.01㎛ can not exhibit sufficient runability, particles larger than 0.5㎛ may form coarse protrusions on the surface of the film in the case of the first component particles may cause breakdown in the manufacturing of the capacitor. In addition, when the content of the fine particles is less than 0.01% by weight can not exhibit sufficient running performance, when the content of more than 0.5% by weight does not appear the effect by the fine particles any more.

In this invention, it is also preferable to control so that the difference ((DELTA) h, micrometer) of the micrometametry method and weight average thickness which measured 10 sheets simultaneously can satisfy the following formula (3).

0.1 ≤ Δh ≤ 0.3 (3)

If Δh is less than 0.1, sufficient runability cannot be obtained from the film. If Δh is more than 0.3, the distance between the electrodes in the capacitor is increased, the capacitance is lowered, and the characteristics of the capacitor are deteriorated.

As described above, the film that satisfies the requirements of the present invention has excellent workability during film production and processing, and can obtain high capacitance and at the same time, the particles such as colloidal silica or alumina of the second component used are poly It has good affinity with ester and no void is generated around the particles, so it is excellent in breakdown as a capacitor.

On the other hand, in the manufacturing method of the polyethylene terephthalate of the layer (A) used in the present invention, for example, dimethyl terephthalate and ethylene glycol are supplied to a transesterification reactor, and then a calcium compound and antimony trioxide are added as a transesterification catalyst. After heating, the methanol was distilled off, and the phosphorus compound of Formula (1) mentioned above and particles of the first and second components were added to complete the transesterification reaction over 4 hours, and then excess ethylene glycol was distilled off by distilling bishydro. Oxyethyl terephthalate (BHT) is obtained, and then BHT is transferred to a polymerization reactor, followed by a slow heating and depressurization, and a polycondensation reaction to proceed. Finally, the temperature of the reactor is 290 ° C. and the vacuum degree is 1.0 mmHg or less. Terephthalate can be obtained. In the case of the polyethylene terephthalate of the layer (B), a polymer having excellent heat resistance can be obtained by using a conventionally known method and a phosphorus compound of the general formula (1).

After drying sufficiently by the method of film-forming the polyester prepared above, it is extruded through a feed block in which the polymer obtained above is melted at 280-300 ° C. using two extruders to join the polymers, and 20- After cooling and solidifying to a casting drum at 60 DEG C to obtain an amorphous unstretched film, the unstretched film is uniaxially stretched, and then biaxially stretched in a direction perpendicular to the uniaxial direction and heat-set to obtain a final film. May be exemplified. At this time, the longitudinal stretching is carried out by using a general roll, the material of the roll is not good adhesion such as Teflon, silicon. The final film can be obtained using the drawing method of extending | stretching temperature 90-130 degreeC, drawing ratio 3.5 to 5 times, and heat-setting at 181-230 degreeC for 0.5 to 30 second.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. The specific values of the films obtained at this time were measured by the following methods.

Heat resistance

The polymer of the chip state prepared through the polymerization process was placed in a vacuum dryer, and then treated under the following conditions, and then graded 1 to 4 based on b value (yellowsh) using a color difference meter at room temperature.

Sample volume: 500 ~ 1000 chips

Treatment temperature: 240 ℃

-Processing time: 7hr.

Measuring instrument: Color difference meter ZE2000 (Nippon Denshoku)

-Rating criteria

b value Less than 3 Less than 3 ~ 6 Less than 6-15 15 or more Rating 1st grade 2nd class Level 3 Grade 4

importance

The density gradient tube consisting of carbon tetrachloride and normal-heptane was maintained at 25 ° C. and specific gravity was measured by up and down method.

Ultimate viscosity

2.0 g of each copolyester was dissolved at 1,1,2,2-tetrachloroethanephenol (60/40 weight percent) mixed solvent and measured at 25 ° C.

Particle size

The average particle diameter of the particle slurry was measured using a particle size distribution analyzer (ZETASIZER 4, manufactured by MALVERN), and the particle size on the film was measured using an electron microscope. The average particle diameter of the particle was 50% of the volume fraction obtained by converting the particle into a spherical shape. It was made.

Film mechanical properties

Using Instron's UTM MODEL-4206, a 50 mm long, 20 mm wide, 125 μm thick film was stretched at a rate of 200 mm / cm at room temperature and 65% relative humidity to create a load-elongation chart. Calculated and evaluated.

Film heat shrinkage

After placing a 100 mm x 100 mm film in a hot air dryer and heat-treating at 150 DEG C for 30 minutes, the length of the deformed film at room temperature was obtained from the following equation.

L ₀ -L

Shrinkage (%) = --------- × 100

L ₀

Where L ₀ is the length before treatment and L is the length after treatment.

Film surface resistance

Surface resistance was measured at 20 ° C. and 65% RH using an insulation resistance meter manufactured by Hurett, USA. The applied voltage is 500V and the unit is Ohm.

Film dielectric constant

According to the American standard measurement method (ASTM D150-92), it was measured under the conditions of 20 ℃, 1 kHz.

Film Insulation Breakdown Voltage

According to the American standard measuring method (ASTM D149-92), it measured using the instrument of Rosemount Analytical.

Film Runability (Active)

The running property of the film is expressed by the coefficient of kinetic friction and its measurement is measured on a tape according to ASTM D-1894. The measurement was carried out in an atmosphere of 23 ± 1 ° C. and a humidity of 50 ± 5% Rh. The size of the sample used was 15 mm in width and 150 mm in length, and the tensile speed was 20 mm / minute.

Measurement of the film Δh

The micrometer thickness (hm) was obtained by dividing the values of 10 films by using a micrometer in accordance with JIS B-7502, and dividing the value by 10. The weight method (hw) was calculated by the following equation.

Δh was obtained by the following equation.

Δh = hm-hw (μm)

Film lamination thickness

Using a secondary ion mass spectrometer (SIMS), the concentration ratio (M + / C +) of the carbon element of the polyester and the element caused by the high density particles in the film in the range of 3000 nm deep from the surface is defined as the particle concentration. Analyze in the thickness direction. Since the surface layer has an interface called a surface, the particle concentration is low, and the particle concentration increases as it goes deeper from the surface.

In the case of the film in the present invention, at low particle concentrations, the maximum increases and then begins to decrease. From this particle distribution curve, the depth at which the surface particle concentration is ½ of the maximum value (½ at the maximum when the particle concentration decreases) is evaluated as the lamination degree.

① Measuring device

Secondary Ion Mass Spectrometer (SIMS) Germany, ATOMIKA, A-DIDA3000

② Measurement condition

-Primary ion type: O ₂ ⁺

Primary Ion Acceleration Voltage: 12KV

Primary ion current: 200nA

Rasta area: 400㎛ ²

Analysis area: Gate 30%

-Vacuum degree: 6.0 × 10 ^-9 Torr

-E-GUN: 0.5 KV-3.0A

Capacitor element capacity

Aluminum is deposited on the film in a vacuum deposition apparatus. The width of the evaporation part was 10 mm, and margins of 2 mm from left and right sides of the undeposition part were cut and wound to prepare a condenser element. The capacitance of the condenser element was measured under the condition of 1KHz and 0.3Vrms by using 'RLC Bridge Bridge' manufactured by General Radio under the atmosphere of 23 ° C and 50% Rh.

Measurement of capacitor breakdown voltage

The electrode terminal of the capacitor element obtained in (13) is connected to the voltage applying electrode and the ground electrode of the tester using a 100 KV DC withstand voltage tester, respectively. Increase the applied voltage of the tester at a boosting speed of 100 V / sec and measure the voltage when the capacitor breaks and a short circuit occurs.

Capacitor element heat resistance

The capacitor is applied with 400V DC under an atmosphere of 60 ° C. and 95% RH, and the life evaluation is continuously performed under the same conditions. 1000 hr by default. Subsequent existence without loss of capacitor function (short circuit) is considered to have passed the evaluation. In addition, it is judged to be satisfactory when the remaining time becomes longer as a result of the heat resistance test.

Example 1

100 parts by weight of dimethyl terephthalate, 70 parts by weight of ethylene glycol, 0.09 parts by weight of calcium acetate tetrahydrate, and 0.03 parts by weight of antimony trioxide were added to a transesterification reactor equipped with a stirrer, a rectification tower, and a condenser. After that, the phosphorus compound of the general formula (1) having the structure shown in Table 1 was added to the amount shown in Table 2, and the spherical silica particles (first component particles) having an average particle size of 1.0 µm were 0.25% by weight, and the average particle diameter was 0.05. The colloidal silica particles (second component particles) having a thickness of 0.2 µm were added thereto, the excess ethylene glycol was distilled off, and the transesterification reaction was completed over 4 hours to obtain bishydrooxyethyl terephthalate (BHT). Subsequently, after the BHT was transferred to a polymerization reactor, the polycondensation reaction was gradually carried out while heating and depressurizing. Finally, the polymer (a) having an intrinsic viscosity of 0.62 was obtained at a reactor temperature of 285 ° C. and a vacuum of 0.2 mmHg or less.

Furthermore, the polymer (b) was obtained for the polymer which does not contain particle | grains using said polymerization process and the same phosphorus compound.

A / B / A The polymer (a) used in the layer (A) of the three-layer structure and the polymer (b) used in the layer (B) were vacuum dried at 160 ° C. for 6 hours, and the polymers were then used by two extruders. It was melted at 290 ℃ and extruded through a feed block to join the polymer and cooled and solidified in a casting drum at 30 ℃ using an electrostatic casting method to obtain an amorphous non-oriented film of 80㎛. Subsequently, the unstretched film was stretched 4.4 times in the longitudinal direction at 120 ° C., then stretched 4.1 times at a temperature of 120 ° C. in the transverse direction, and heat-set at 220 ° C. for 3 seconds to give a 4.5 μm biaxial orientation composite having a t / d ratio of 1.0. A polyester film was obtained. The general physical properties and the condenser element characteristics of the obtained film were measured and shown in Table 2.

Example 2

Except for using the phosphorus compound having the structure shown in Table 1 and the components and amounts shown in Table 2 was carried out in the same manner as in Example 1 to obtain a 4.5 ㎛ biaxially oriented composite polyester film having a t / d ratio of 0.5, Various physical properties and condenser element characteristics of the obtained film were measured and shown in Table 2.

Example 3

Except for using the phosphorus compound of the structure shown in Table 1, and using the components and amounts shown in Table 2 to give a 4.5㎛ biaxially oriented composite polyester film in the same manner as in 1, the overall physical properties and capacitor elements of the film obtained The properties were measured and shown in Table 2.

Example 4

Alumina having 0.3 wt% of spherical silica particles having an average particle size of 1.5 μm as the first component particles and an average particle diameter of 0.05 μm as the second component particles, except that the phosphorus compound having the structure shown in Table 1 was used. A polymer (a) containing 0.2% by weight of particles and a polymer (b) containing no particles were laminated to obtain a 4.5-micron biaxially oriented composite polyester film having a t / d ratio of 1.0. The properties were measured and shown in Table 2.

Comparative Example 1

Except for using the phosphorus compound having the structure shown in Table 1, and using the components and amounts shown in Table 2, was carried out in the same manner as in Example 1 to obtain a 4.5㎛ biaxially oriented composite polyester film, the overall physical properties of the film obtained And capacitor characteristics were measured and shown in Table 2.

Comparative Example 2

A polymer having the same composition as in Example 1 except for using the phosphorus compound having the structure shown in Table 1, containing 0.25 wt% of spherical silica particles having an average particle size of 1.0 μm as the first component particles and not including the second component particles. (a) and a polymer (b) containing no particles were laminated to obtain a 4.5 µm biaxially oriented composite polyester film having a t / d ratio of 1.0. Indicated.

Comparative Example 3

Except for using the phosphorus compound having the structure shown in Table 1 in the same manner as in Example 1, 0.3 wt% calcium carbonate particles having an average particle size of 1.5㎛ as the first component particles and a colo having an average particle diameter of 0.05㎛ as the second component particles A polymer (a) containing 0.2% by weight of silica particles and a polymer (b) containing no particles were laminated to obtain a 4.5 µm biaxially oriented composite polyester film having a t / d ratio of 1.0. The capacitor device characteristics were measured and shown in Table 2.

Table 1 (R ₁ , R ₂ , R ₄ have a common structure)

TABLE 2

As confirmed in the above embodiment, the biaxially oriented polyester film provided in accordance with the present invention exhibits excellent mobility and workability in the manufacture of a capacitor due to excellent reactivity of the film surface, and can exhibit excellent electrical and heat resistance characteristics. Since it has advantages, it can be very useful as a film for capacitors.

Claims (5)

When the resin obtained by polycondensation reaction using at least one dicarboxylic acid or terephthalate and at least one glycol as a main component is produced through a film forming process, a biaxially oriented polyester film is produced. A method for producing a biaxially oriented polyester film, comprising adding a satisfactory propinic acid derivative so that the content of phosphorus is 0.01 to 1% by weight and the content of chlorine atoms is 0.01 to 4.0% by weight. General formula (1) (Wherein R ₁ is a phenyl group, a cycloalkyl group, a haloalkyl group, a haloaryl group, with or without hydrogen, methyl, or a substituent having 1 to 5 carbon atoms, and the substituent is a C1-5 alkyl group, a metal sulfonate group, a carbon number) And an amine group containing 1 to 6, R ₂ is an ethylene group having a substituent, and the R ₃ substituent is bis- (4-hydroxyphenyl) propane containing 1-8 chlorine groups in an aryl group, It is selected from bis- (4-hydroxyphenyl) methane containing 1-8 chlorine groups, bis- (4-hydroxyphenyl) hexachloropropane and propanediol containing 1 chlorine group in an aryl group.) A resin obtained by polycondensation reaction with at least one dicarboxylic acid or terephthalate and at least one glycol as a main component is a binder resin, the specific gravity of the film is 1.365 to 1.420, the surface resistance is 10 ¹⁶ to 10 ¹⁴ ohms, and the dielectric constant is It is in the range of 3.0-3.5, and the biaxially-oriented polyester film characterized by the heat resistance grade of this polymer being 1 grade. The film structure is a film structure of the three-layer structure of A / B / A, layer (A) is a spherical silica having an average particle diameter of 0.5 to 2.0 ㎛ as the first component particles of the particles used. 0.01 to 0.5% by weight of the second component particles smaller in size than the first component particles, 0.01 to 0.5% by weight of inert inorganic particles having an average particle diameter of 0.01 to 0.5㎛, the layer (B) contains no particles Method for producing a biaxially oriented polyester film, characterized in that not to. 4. The relationship between the average particle diameter (d: mu m) of the first component particles added to the layer (A) and the thickness (t: mu m) of the laminated layer (A) satisfies the following formula (2): and 0.1 ≤ ｔ / d ≤ 5.0 (2) A method of producing a biaxially oriented polyester film, wherein the difference (Δh) between the micromethod thickness and the weight average thickness of the entire film satisfies the following Equation (3). 0.1 ≤ Δh ≤ 0.3 (3) The method for producing a biaxially oriented polyester film according to claim 3, wherein the inert inorganic particles of the second component of the layer (A) are colloidal silica or alumina.