JP3306178B2 - Polyethylene-2,6-naphthalate film for condenser - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a polyethylene-2,6 for a condenser having excellent running property and strength in a processing step.
A naphthalate film;

[0002]

2. Description of the Related Art Polyester films, especially biaxially oriented films represented by polyethylene terephthalate, have excellent physical and chemical properties, and have been particularly awarded as capacitor derivatives. . In recent years, when the thickness of a base film is reduced due to an increase in capacitor capacity and miniaturization, there is a remarkable demand for dimensional stability of the base film and improvement in running properties in a processing step for improving workability in the processing step. It is difficult to satisfy such requirements with the conventional particle-containing polyethylene terephthalate film.

[0003]

In view of such circumstances, the present inventors have satisfied appropriate running properties and dimensional stability at the same time.
As a result of intensive studies to provide a film having an excellent dielectric breakdown voltage, which is an important characteristic of a capacitor, polyethylene-2,6-
The inventors have found that a naphthalate film can satisfy such required characteristics, and have completed the present invention.

That is, the gist of the present invention is that the primary particles have an average particle diameter of 0.01 to 0.1 μm and a pore volume of 0.05 to 0.1 μm.
Porous sedimentable silica particles (A) having an average particle diameter of 0.1 to 0.7 μm having an average particle diameter of 0.5 to 0.5 ml / g and a specific surface area of 30 to 150 m ² / g, or an average particle diameter of 0.7 to 3.0. Polyethylene for a capacitor obtained by blending porous silica particles (B) having a specific surface area of 0 m ² / g or more so as to satisfy the following formulas (1), (2) and (3) at the same time. , 6-naphthalate film. 0 < a ≦ 2 (1) 0 ≦ b ≦ 2 (2) 0.2 ≦ a + b ≦ 2 (3) (in the above formula, a is a silica particle (A) in the film) And b represents the content [wt%] of the silica particles (B) in the film.)

Hereinafter, the present invention will be described in detail. The polyethylene-2,6-naphthalate referred to in the present invention is 2.6.
-Refers to a polyester obtained using naphthalenedicarboxylic acid or its ester and ethylene glycol as main starting materials, but may contain other third components.
In this case, as the dicarboxylic acid component, for example, one kind such as isophthalic acid, terephthalic acid, adipic acid, and sebacic acid can be used. Further, as the glycol component, one or more of diethylene glycol, propylene glycol, butanediol, 1,4-cyclohexanedimethanol, neopentyl glycol and the like can be used. In any case, the polyethylene-2,6-naphthalate of the present invention refers to a repeating structural unit of 8
0% or more refers to a polyester having ethylene-2.6-naphthalate units.

[0006] The polyethylene-2,6-naphthalate film of the present invention refers to the polyethylene-2,6-naphthalate film.
-Refers to at least a uniaxially oriented polyester film using naphthalate as a starting material, and a known method can be used for producing the polyester film. For example, usually after being melt-extruded into a sheet at 290 to 330 ° C.,
After cooling and solidifying at ~ 80 ° C to form an amorphous sheet,
The film is stretched biaxially or sequentially at a temperature of up to 170 ° C. in the longitudinal and transverse directions so as to have an area magnification of 4 to 20 times.
A method of performing heat treatment at 70 ° C. can be used. When stretching in the longitudinal and transverse directions, each may be stretched in one step, or if necessary, may be stretched in multiple steps, or a heat treatment section for relaxing orientation may be provided between the multiple steps. After the biaxial stretching, the film may be stretched again before being subjected to the next heat treatment step. This re-stretching can be performed in any of the vertical and horizontal directions, or may be performed in both directions. In particular, for higher strength, after the biaxial stretching, 140 to 200
A method of performing re-stretching by 1.05 to 4.0 times in the vertical and horizontal directions at a temperature of ° C. and then performing a heat treatment is often employed.

The most important feature of the present invention is that the average particle diameter of the constituent primary particles is 0.01 to 0.1 μm and the pore volume is 0.0
Porous sedimentable silica particles (A) having an average particle diameter of 0.1 to 0.7 μm having a specific surface area of 5 to 0.5 ml / g and a specific surface area of 30 to 150 m ² / g, or an average particle diameter of 0.7 to 3 Incorporating porous silica particles (B) having a specific surface area of 200 m ² / g or more into a polyester film so that the following formulas (1), (2) and (3) are simultaneously satisfied. is there. 0 < a ≦ 2 (1) 0 ≦ b ≦ 2 (2) 0.2 ≦ a + b ≦ 2 (3) (in the above formula, a is a silica particle (A) in the film) And b represents the content [wt%] of the silica particles (B) in the film.)

The porous silica particles referred to in the present invention are:
Both (A) and (B) can be basically obtained by a method called a so-called wet method, for example, by reacting sodium silicate with a mineral acid to synthesize particles containing silica as a main component. Then, at the time of the particle synthesis, the characteristics can be controlled by adjusting the reaction temperature, coexisting ions, and the like. Silica particles (A) in the present invention
The average particle size of the primary particles is in the range of 0.01 to 0.1 μm. If the average particle size of the constituent primary particles is less than 0.01 μm, ultrafine particles are generated by crushing at the stage of slurrying, which is not preferable because they form aggregates. On the other hand, if the average particle diameter of the constituent primary particles exceeds 0.1 μm, the porosity of the particles is lost, and as a result, the affinity for the polyester which depends on the deformability of the silica particles is lost, which is not preferable. The pore volume of the silica particles (A) is 0.05 to 0.5 m.
1 / g, and the specific surface area is in the range of 30 to 150 m ² / g. The pore volume is less than 0.05 ml or the specific surface area is 3
If it is less than 0 m ² / g, the porosity of the particles is lost, which is not preferable. Further, if the pore volume exceeds 0.5 ml / g or the specific surface area exceeds 150 m ² / g, the amount of silanol groups in the particles becomes too large, so that aggregates are preferably formed at the stage of slurrying. Absent.

The average particle size of the silica particles (A) in the present invention is 0.1 to 0.7 μm, preferably 0.4 to 0.6 μm.
It is. If the average particle size is less than 0.1 μm, the running property of the film is insufficient, and if it exceeds 0.7 μm, the affinity with the polyester is insufficient, which is not preferable. The specific surface area of the silica particles (B) in the present invention is 200 m ² / g or more, and the average particle size is 0.7 to 3.0 μm, preferably 0.7 to 1.5 μm, more preferably 0.7 to 1 μm. .0
μm. If the specific surface area is less than 200 m ² / g, the affinity with the polyester becomes insufficient and the polyester falls off the film, which is not preferable. On the other hand, if the average particle size is less than 0.7 μm, the effect of improving runnability, particularly when the film is thinned, is insufficient, and if it exceeds 3.0 μm, the surface roughness of the film becomes too large, which is not preferable. .

Further, when the above formulas (1), (2) or (3) are not satisfied, the surface properties and running properties of the film become inferior, and the withstand voltage characteristics of a capacitor deteriorate.

The method of blending the particles used in the present invention with the polyester as a film-forming raw material is not particularly limited, and a known method can be employed. For example, when the particles are obtained as an ethylene glycol slurry dispersion, when the polycondensation reaction proceeds at any stage of the polyester production process, preferably after the completion of the esterification or transesterification reaction and before the start of the polycondensation reaction, Good. The polyethylene-2,6-naphthalate film of the present invention has a temperature of 150 ° C.
The shrinkage in the vertical and horizontal directions after heat treatment for 2 hours is 1.5% or less, and the shrinkage in the horizontal direction is 1.0%.
The following is preferred. If these conditions are not satisfied, in the case of a thin film, the dimensional stability at the time of manufacturing a capacitor tends to deteriorate, and problems such as a change in the characteristics of the capacitor, such as a change in capacitance and an increase in dielectric loss tangent (tan δ), occur. May occur. In particular, when the shrinkage in the transverse direction exceeds 1.5%, the film shrinks in the transverse direction in the metallikon step at the time of forming a capacitor,
A defect occurs at a contact portion between the end face electrode and the metal film on the film due to the metallikon. As a result, a tan δ value which is one of the capacitor characteristics, particularly, a ta
n δ values tend to be high.

[0012]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to the following examples unless it exceeds the gist. The methods and definitions for measuring various physical properties and characteristics in the examples are as follows. In Examples and Comparative Examples,
"" Means "parts by weight". (1) Average particle size: Centrifugal sedimentation type particle size distribution analyzer (SA-CP manufactured by Shimadzu Corporation)
Integrated volume fraction 5 in equivalent spherical distribution measured by type 3)
The diameter (particle size) of 0% was defined as the average particle size. The particle diameter of the constituent primary particles was measured by electron microscope image processing. (2) Pore volume and specific surface area Using a fully automatic surface area measuring device (Carlo Elba),
It was measured by a nitrogen adsorption / desorption method. (3) Film Surface Roughness (Average Roughness) According to the method described in Japanese Industrial Standard JIS B0601, a surface roughness measuring instrument (SE-3) manufactured by Kosaka Laboratory Co., Ltd.
The center line average roughness (Ra) was determined using F).

(4) Runnability Two films cut to a width of 15 mm and a length of 150 mm are stacked on a smooth glass plate, and a rubber plate is placed thereon, and a contact pressure of the two films is set to 2 g / cm ^2. As 20m
Measure the frictional force by sliding the films at m / min,
The friction coefficient at the point of sliding by 5 mm was determined as the dynamic friction coefficient. The measurement was performed at a temperature of 23 ° C. ± 1 ° C. and a humidity of 50% ± 5 ° C.
% Atmosphere. (5) Young's modulus of film Tentes Co., Ltd. tensile tester Intesco Model 20
A sample film having a length of 300 mm and a width of 20 mm was pulled at a strain rate of 10% / min in an environment adjusted to a temperature of 23 ° C. and a humidity of 50% RH using a type 01, and the initial stress of the tensile stress-strain curve was obtained. The calculation was performed by the following equation using the straight line portion. Young's modulus (kg / mm ² ) = △ σ / △ ε (wherein △ σ is a stress difference due to the original average cross-sectional area between two points on a straight line, and △ ε is a strain difference between the same two points. )

(6) Withstand voltage characteristics Measurements were made in accordance with JIS C-2319. That is, using a 10 kV DC withstand voltage tester, 23 ° C., 50%
Under an atmosphere of RH, the voltage was increased at a rate of 100 V / sec, and the voltage when the film was broken and short-circuited was read. (7) Dielectric loss tangent (tan δ) value Broadband dielectric loss measuring device (TR-1 manufactured by Ando Electric Co., Ltd.)
(Type) at 125 ° C. and 1 kHz. The dielectric loss tangent (tan δ) value is expressed in%.

Example 1 (Preparation of slurry) The average particle size of the particles was 0.45 μm, the average particle size of the constituent primary particles was 0.05 μm, and the pore volume was 0.09 ml /
g, 90 parts of ethylene glycol was added to 10 parts of the precipitated porous silica particles having a specific surface area of 70 m ² / g, and 1000 parts were mixed with a homomixer (TK homomixer manufactured by Tokushu Kika Kogyo Co., Ltd.).
The mixture was dispersed at 0 rpm for 60 minutes and filtered through a 1000 mesh wire mesh filter to obtain an ethylene glycol slurry.

(Production of polyester) naphthalene-2,
100 parts of dimethyl 6-dicarboxylate, ethylene glycol 60 and 0.03 part of manganese acetate tetrahydrate were placed in a reactor, heated and heated, and methanol was distilled off to carry out a transesterification reaction. It took 4 hours from the start of the reaction. 23
The temperature was raised to 0 ° C., thereby substantially terminating the transesterification reaction. Next, 7 parts of an ethylene glycol slurry of the above silica particles were added, and 0.015 part of ethyl acid phosphate and 0.04 part of antimony trioxide were added, and a polycondensation reaction was carried out by a conventional method to give an intrinsic viscosity of 0. .51 of polyethylene-2,6-naphthalate. The obtained polymer was subjected to solid-state polymerization at 0.3 mmHg and 235 ° C. for 8 hours to obtain polyethylene-2,6-naphthalate having an intrinsic viscosity of 0.65.

(Production of Film) The polymer was extruded in a sheet form from an extruder at 295 ° C., and an amorphous sheet was obtained by using an electrostatic cooling method. Next, after stretching 3.9 times in the longitudinal direction and 4.0 times in the transverse direction with a tenter at 130 ° C., 2
Heat treatment was performed at 20 ° C. to obtain a 2.5 μm-thick polyethylene-2,6-naphthalate film, and its characteristics were evaluated. (Production of a capacitor) Aluminum was vapor-deposited on the surface of the obtained film, and the film was overlapped and wound, a metallikon was applied to an end face, and leads were attached to each electrode terminal to prepare a capacitor.

Comparative Example 1 (Preparation of slurry) 90 parts of ethylene glycol was added to 10 parts of porous silica particle powder having an average particle diameter of 0.90 μm and a specific surface area of 300 m ² / g, and a homomixer (TK manufactured by Tokushu Kika Kogyo Co., Ltd.) was used. The mixture was dispersed at 10,000 rpm for 60 minutes using a homomixer, and filtered through a 1000 mesh wire mesh filter to obtain an ethylene glycol slurry.

(Production of Polyester) The same procedure as in Example 1 was repeated except that 7 parts of the above-mentioned silica particle ethylene glycol slurry was added.
2,6-Naphthalate was obtained. (Production of Film and Capacitor) The same procedure as in Example 1 was carried out except that the thickness of the obtained polymer extruded in a sheet form from an extruder was changed. A naphthalate film was obtained, and a condenser was obtained.

Example 2 (Preparation of slurry) The average particle diameter of the constituent primary particles was 0.45 μm, and the average particle diameter was 0.4 μm.
05 μm, pore volume 0.09 ml / g, specific surface area 70 m
92 parts of ethylene glycol were added to 6 parts of ² / g precipitated silica particles and 2 parts of porous silica particles having an average particle size of 0.90 μm and a specific surface area of 300 m ² / g,
1 with a homomixer (TK homomixer manufactured by Tokushu Kika Kogyo)
The mixture was dispersed at 0000 rpm for 60 minutes, and filtered through a 1000 mesh wire mesh filter to obtain an ethylene glycol slurry.

(Production of polyester) Except for adding 5 parts of an ethylene glycol slurry of the silica particles, the same procedure as in Example 1 was repeated to prepare a polyethylene containing silica particles.
2,6-Naphthalate was obtained. (Production of film and capacitor) Except for changing the thickness when extruding the obtained polymer in a sheet form from an extruder, the same procedure as in Example 1 was repeated except that polyethylene-2,6-polyethylene having a thickness of 0.9 μm was used. A naphthalate film was obtained, and a condenser was obtained.

COMPARATIVE EXAMPLE 2 The same procedure as in Example 1 was repeated except that 25 parts of the same ethylene glycol slurry of precipitated porous silica particles as in Example 1 was added.
A 2,6-naphthalate film was obtained, and a condenser was obtained. Comparative Example 3 The average particle diameter of the constituent primary particles was 0.90 μm and the average particle diameter was 0.90 μm.
08 μm, pore volume 0.10 ml / g, specific surface area 90 m
Except for using ² / g sedimentable porous silica particle powder,
In the same manner as in Example 1, a polyethylene-2,6-naphthalate film having a thickness of 2.5 μm was obtained, and further a capacitor was obtained.

[0023] In the same manner as all but the addition of 25 parts of ethylene glycol slurry of a similar porous silica particles as Comparative Example 4 Comparative Example 1 Comparative Example 1, the thickness 1.5μm polyethylene-2,6
A naphthalate film was obtained, and a condenser was obtained. Comparative Example 5 The same procedure as in Comparative Example 1 was carried out except that porous silica particles having an average particle diameter of 0.45 μm and a specific surface area of 300 m ² / g were used. -A naphthalate film was obtained to obtain a condenser. The thickness in the same manner as all but adding 30 parts of a mixture of ethylene glycol slurry of the same precipitated porous silica particles and porous silica particles as Comparative Example 6 Example 2 Example 2 0.9
A μm polyethylene-2,6-naphthalate film was obtained, and a condenser was obtained.

[0024]

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

[Table 3]

[0028]

Industrial Applicability The film of the present invention is particularly excellent in running properties when thinned and withstand voltage characteristics when used as a capacitor, is useful as a base film for capacitors, and has high industrial value.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H01G 4/00-4/10 H01G 4/14-4/42

Claims (1)

(57) [Claims] An average particle size of the primary particles is from 0.01 to 0.1.
μm, average particle size of 0.1 to 0.7 having a pore volume of 0.05 to 0.5 ml / g and a specific surface area of 30 to 150 m ² / g.
μm porous sedimentable silica particles (A), or an average particle size of 0.7 to 3.0 μm and a specific surface area of 200 m ² /
A polyethylene-2,6-naphthalate film for a capacitor, comprising a porous silica particle (B) having a weight of at least g and satisfying the following formulas (1), (2) and (3) at the same time. 0 < a ≦ 2 (1) 0 ≦ b ≦ 2 (2) 0.2 ≦ a + b ≦ 2 (3) (in the above formula, a is a silica particle (A) in the film) And b represents the content [wt%] of the silica particles (B) in the film.)