JP2969904B2 - High dielectric constant film and capacitor using the same - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a high dielectric constant film having excellent heat resistance, mechanical properties, electrical properties, and surface properties.

[Related Art] In recent years, the miniaturization of electric devices has been progressing, and the components used have been miniaturized. However, there is a demand for miniaturization of capacitors as well. Therefore, a film used as a dielectric of a film capacitor is required to have a high dielectric constant, and a high heat resistance is required at the same time as the process is simplified. In order to satisfy these requirements, a method of adding an inorganic filler to an aromatic polyamide film has been proposed (JP-A-1-248404).

[Problems to be Solved by the Invention] However, although the mechanical properties are considerably improved by selecting the aromatic polyamide as the matrix polymer to which the inorganic filler is added, it is still not enough, and when the film is processed, Problems such as cutting and tearing occur. As a result, there have been problems such as a decrease in production yield and a decrease in product reliability.

The present invention has excellent heat resistance of the aromatic polyamide film,
It is an object of the present invention to provide an inorganic polyamide-containing aromatic polyamide film that can obtain excellent characteristics when a capacitor is obtained by solving problems such as film breakage and tear while maintaining mechanical characteristics. I do.

[Means for Solving the Problems] The present invention relates to a para-oriented aromatic polyamide A having a linear structure containing at least 60 mol% of a repeating unit represented by the formula (1) or the formula (2); (3) A film comprising an aromatic polyamide B having a structure in which the polymer structure containing the repeating unit represented by the formula (4) or more by 50 mol% or more is not linear, and an inorganic filler,
A high dielectric constant film comprising aromatic polyamide B in an amount of 2 to 40% by weight based on the total amount of aromatic polyamides A and B, and an inorganic filler in the film in an amount of 30% by weight or more. And a capacitor using the same.

The para-oriented aromatic polyamide A of the present invention is a repeating unit represented by the general formula HN-Ar ₁ -NHCO-Ar ₂ -CO (1) or HN-Ar ₃ -CO (2) It contains at least 60 mol%, and more preferably at least 70 mol%. The para-orientation system is a linear structure including at least one aromatic ring in which Ar ₁ , Ar ₂ , and Ar ₃ are bonded to para, or a naphthalene skeleton. Some include a linear polymer structure. Ar ₁ , A
r ₂ and Ar ₃ may have the same composition or different compositions. Ar ₁ , Ar ₂ ,
The following are typical examples of Ar ₃ .

Also, part of the hydrogen on these aromatic rings are halogen (especially chlorine), a nitro group, an alkyl group of C ₁ -C ₃ (especially methyl), such as alkoxy groups C ₁ -C ₃ Also includes those substituted with a substituent.

In particular, from the viewpoint of improving the humidity characteristics of the film and improving the film forming property, those obtained by introducing a halogen group, particularly chlorine, into an aromatic ring are more preferable.

For example, (Where p and q are integers of 0 to 4).

The composition of less than 40 mol% is not particularly limited,
Those having an amide bond represented by the above formula (1) or (2) are preferably copolymerized, and Ar ₁ , Ar ₂ , A
a structure corresponding to r _3, include the following structures.

Wherein X is _{-O -, - CH 2 -,} - SO 2 -, - S -, - CO
—, —C (CH ₃ ) ₂ — and the like. Some of the hydrogen atoms on these aromatic rings may be halogen groups (particularly chlorine), nitro groups, C ₁ -C ₃ alkyl groups (particularly methyl groups), C ₁ -C ₃
May be substituted with a substituent such as an alkoxy group.

Next, the aromatic polyamide B of the present invention is a compound represented by the general formula HN—Ar ₄ —NHCO—Ar ₅ —CO (3) or HN—Ar ₆ —CO (4) %, More preferably 70 mol% or more. here
Ar ₄ , Ar ₅ , Ar ₆ contains an aromatic ring or a naphthalene skeleton,
The polymer structure is not linear. Ar ₄ , Ar ₅ ,
Ar ₆ may have the same composition or different compositions. Representative examples include the following (5). However, at least one of Ar ₄ and Ar ₅ may be selected from (5), and the other may be selected from representative example (6).

That is, if at least one of Ar ₄ and Ar ₅ does not have a linear structure, the other may have a linear structure.

Wherein Y _{is, -O -, - CH 2 -} , - SO 2 -, - S -, -
_{CO -, - C (CH 3} ) 2 - and the like.

Specific examples of the aromatic polyamide B include: And the like.

Further substitution of part of the hydrogen on the ring of these aromatic rings, halogen (especially chlorine), a nitro group, an alkyl group of C ₁ -C ₃ (especially methyl), an alkoxy group of C ₁ -C ₃ Also includes those substituted with a group. In particular, in order to improve the humidity characteristics of the film, it is more preferable that a halogen group, particularly chlorine, is introduced into at least one or more aromatic rings in the repeating unit.

The aromatic polyamide film containing the inorganic filler of the present invention is mainly composed of a blend of a para-oriented aromatic polyamide A and an aromatic polyamide B, and the aromatic polyamide B is an aromatic polyamide A. ,
It is necessary to contain B in an amount of 2 to 40% by weight based on the total amount of B. Preferably 5 to 30% by weight, more preferably 5 to 20%
wt%. When the amount is less than 2 wt%, the strength, rigidity and heat resistance of the film are good, but there is no effect on the cutting properties and tear of the film. If the content is more than 40 wt%, the mechanical properties decrease and the film becomes brittle, which leads to the breakage or tearing of the film. In addition, humidity characteristics and heat resistance also deteriorate. In addition, a lubricant (including organic and inorganic fine particles) within a range not to impair the present invention,
Antioxidants, antistatic agents and other polymers may be blended.

As the inorganic filler used in the present invention, when added to a polymer in which the above-mentioned para-oriented rigid aromatic polyamide A and flexible aromatic polyamide B are blended, a dielectric constant higher than the dielectric constant of the polymer itself is expressed. In consideration of compatibility with the polymer, a metal oxide is preferable.
Specifically, barium titanate, zinc titanate, strontium titanate, calcium titanate, lead titanate,
Magnesium titanate, titanium oxide, barium antimonate, magnesium antimonate, strontium antimonate, calcium antimonate, magnesium antimonate, lead antimonate, barium stannate, strontium stannate, and the like, and their composite compounds, solid solutions, It may be a simple mixture. In particular, titanium oxide (rutile type, anatase type, and other types are not limited) and metal salts of titanic acid, for example, barium titanate, lead titanate, strontium titanate, or barium titanate, and some barium titanate may be replaced with other metals Replaced or titanium is partially replaced by another metal, specifically (Ba _(1-x) Sr _x ) (Ti _(1-y) Sn _y ) O ₃ (where 0 < x <
Particles such as 1, 0 <y1) are preferred. The shape of the inorganic filler may be any of a sphere, a scale, a needle, an irregular shape, and the like.
The average particle size is 10μm or less, and the ratio of particle size 30μm or more is 30wt
%, More preferably, the average particle size is 5 μm or less, and the ratio of the particle size is 30 μm or more is 15 wt% or less. Outside of this range, the surface properties deteriorate and the mechanical properties are adversely affected.

The amount of the filler to be added depends on the desired dielectric constant, but in order to make the dielectric constant of the film higher than that of the polymer itself, 30 wt% or more is required in the film.
The higher the filler amount, the higher the dielectric constant of the film, but if too much, the mechanical properties of the film deteriorate,
Preferably, the volume fraction is 85 vol% or less, more preferably 75 vol% or less. At this time, the dielectric constant of the film (1
KHz) is preferably 8 to 500. Also, the dielectric loss tangent tanδ
(1 KHz) is preferably 40% or less.

Further, for the purpose of improving the mechanical properties of the film-like material, a silane-based, titanate-based, alumina-based coupling agent or a surfactant may be added at all.

The film of the present invention has a film strength (abbreviated as F-1 value) when the film is elongated by 1% in the longitudinal direction (MD direction).
It is preferable to have 7 kg / mm ² or more. More preferably 10k
g / mm ² or more, more preferably 12 kg / mm ² or more. If it is smaller than this, the film will not withstand high tension during processing of the film, and the film will be easily torn. Width direction (TD
The film strength at 1% elongation in the direction (1) is preferably 5 kg / mm ² or more, more preferably 7 kg / mm ² or more, even more preferably 10 kg / mm ² or more, depending on the method of use of the film.

Further, the moisture absorption of the film of the present invention is preferably 4% or less,
It is preferably at most 3%, more preferably at most 2%.
If it is larger than this, the fluctuation of the coefficient of friction due to the change in humidity becomes large, the running of the film becomes unstable during the processing of the film, the cut or deformation of the film is increased, and the capacitor characteristics are deteriorated.

The film of the present invention has a breaking strength in at least one direction.
It is preferably at least 5 kg / mm ² , more preferably at least 8 kg / mm ² . The elongation at break in at least one direction is preferably 5% or more, more preferably 10% or more. Further, the Young's modulus in at least one direction is preferably 500 kg / mm ² or more, more preferably 600 kg / mm ² or more.

The tear resistance in at least one direction of the film of the present invention,
0.3 kg / μm or more is preferable, and more preferably 0.5 kg / μm
m, more preferably 0.7 kg / μm or more. If it is smaller than this, the film is torn or the cutting property is deteriorated, which is not preferable. In particular, in this range, the capacitor characteristics become good.

Further, the film of the present invention has a surface roughness (center line depth Rp)
Is preferably 10 to 5000 nm, more preferably 100 to 2000 nm
It is. The heat shrinkage in at least one direction is 200 ° C, 1
It is preferably 5% or less at 0 minutes, more preferably 2% or less.

The dielectric breakdown voltage (BDV) is
It is necessary to be 0.1KV or more. Below 0.1 KV, it is not practical. More preferably, it is 0.2 KV or more.

Next, a method for producing the high dielectric constant film of the present invention will be described, but the present invention is not limited thereto.

First, the method for producing an aromatic polyamide is as follows. When the aromatic polyamide is obtained from an acid chloride and a diamine, it is prepared in an aprotic organic polar solvent such as N-methylpyrrolidone (NMP), dimethylacetamide (DMAc), and dimethylformamide (DMF). It is synthesized by solution polymerization or interfacial polymerization using an aqueous medium. When acid chloride and diamine are used as monomers in a polymer solution, hydrogen chloride is by-produced.When neutralizing this, inorganic neutralizers such as calcium hydroxide, calcium carbonate, lithium carbonate, and ethylene chloride are used. Organic neutralizing agents such as oxides, propylene oxide, ammonia, triethylamine, triethanolamine, diethanolamine and the like are used. The reaction between the isocyanate and the carboxylic acid is performed in an aprotic organic polar solvent in the presence of a catalyst. These polymer solutions may be used as such as a polymer solution for blending, or a polymer solution for blending may be prepared by isolating the polymer once and re-dissolving it in the above organic solvent. When an organic neutralizing agent is used, the polymer solution may be left under heating or reduced pressure to evaporate a part or all of the neutralized product and then used as a polymer solution for blending.

In order to obtain the high dielectric constant film of the present invention, the intrinsic viscosity of the aromatic polyamides A and B is preferably 1.0 or more for the former and 0.5 or more for the latter. Mixing of these aromatic polyamides and inorganic fillers, while being polymerized by the above method, or by dissolving the isolated polymer solution again and blending the inorganic filler, or that the inorganic filler is present during the polymerization of the polymer It can also be blended by the method. In some cases, an inorganic salt such as calcium chloride, magnesium chloride, lithium chloride, lithium nitrate, or the like is added to the stock solution thus obtained as a dissolution aid. The polymer concentration in the membrane forming solution is preferably about 2 to 40% by weight.

The film forming stock solution prepared as described above is formed into a film by a so-called solution film forming method. The solution casting method includes a dry-wet method, a dry method, and a wet method.

When a film is formed by a wet method, a method is employed in which the undiluted solution is directly extruded from a die into a film-forming bath, or once extruded onto a support such as a drum or a belt, and then introduced together with the support into the wet bath. You. This bath is generally composed of an aqueous medium, and may contain an organic or inorganic solvent or an inorganic salt in addition to water. The salt and solvent contained in the film are extracted by passing through a wet bath. The time required to pass through the entire wet bath is 10 seconds to 30 minutes, depending on the thickness of the film. Further, if necessary, the film is stretched in the longitudinal direction. Next, drying and heat treatment are performed, and these treatments are generally performed at 200 to 500 ° C. for a total of 1 second to 30 minutes.
In this process, transverse stretching is performed as necessary.

When a film is formed by a dry-wet method, the undiluted solution is transferred from a die to a drum,
Extruded onto a support such as an endless belt to form a thin film,
Next, the solvent is scattered from the thin film layer and dried until the thin film has a self-holding property. Drying conditions are in the range of room temperature to 300 ° C. within 60 minutes. The film after the dry process is peeled from the support and introduced into the wet process, desalting and desolvation are performed in the same manner as in the above wet process, and further stretched, dried,
Heat treatment is performed to form a film.

When a dry process is employed, a film which has been dried on a drum or an endless belt or the like and has self-holding properties is peeled off from these supports and stretched in the longitudinal direction of the film. Further, drying, stretching, and heat treatment for removing the residual solvent are performed, and these treatments are performed at 200 to 500 ° C. for 1 second to 30 minutes.

The film formed as described above is stretched as needed during the film forming process, but the stretching ratio is an area ratio.
It is preferably in the range of 0.8 to 8.0 (the area ratio is defined as a value obtained by dividing the area of the film after stretching by the area of the film before stretching. 1 or less means relaxed), more preferably 1.1. ~ 5.0.

Even if the high dielectric constant film obtained as described above is subjected to glow discharge treatment, corona discharge treatment or the like according to the purpose, it does not impair the present invention.

Next, a method for manufacturing a capacitor will be described. On the film obtained as described above, a metal thin film is formed by a method such as vacuum evaporation, plating, sputtering, or ion plating to obtain a metallized film. Examples of the metal at this time include aluminum, zinc, nickel, and nickel-chromium alloy. Of these, aluminum is preferable in terms of vapor deposition properties and characteristics. This metallized film is wound or laminated and further provided with an external electrode and a sheath to obtain a capacitor of the present invention. Of this capacitor
The change in capacitance before and after immersion in a solder bath at 260 ° C. for 30 seconds is preferably 10% or less, more preferably 7% or less. The change in withstand voltage before and after storage in an atmosphere at 150 ° C. for 1000 hours is preferably 10% or less, more preferably 7% or less. Both are not practical for use outside of this range.

[Effects of the Invention] The high dielectric constant film of the present invention has good heat resistance and humidity characteristics, high strength, and significantly improved cut and tear of the film. As a result, problems such as breakage, breakage, and deformation of the film during processing of the film are extremely small, and the reliability of the product as a capacitor is greatly improved.

[Methods for measuring physical properties and methods for evaluating effects] (1) F-1 value, Young's modulus, breaking strength, breaking elongation Using an Instron type tensile tester, 25
It measured at 60 degreeC and 60% RH. The test piece is 10mm wide and 50mm long,
The pulling speed is 300% / min.

(2) Moisture Absorption A completely dried test specimen was allowed to stand in an atmosphere of 25 ° C. and 75% RH for 48 hours, and was determined from a change in weight.

(3) End tear resistance Measured in accordance with JIS C-2318, film thickness 1μ
Expressed per m.

(4) Surface roughness (center line depth Rp) Using a thin-film level gauge (ET-10) manufactured by Kosaka Laboratory, stylus tip radius 0.5μm, stylus load 5mg, cut-off value 0.008m
The measurement was performed 10 times under the conditions of m and measurement length of 0.5 mm, and the average value was expressed. The definition of Rp is shown, for example, in Jiro Nara, "Method of measuring and evaluating surface roughness" (General Technology Center, 1983).

(5) Solder resistance The sample was immersed in a 260 ° C. solder bath for 30 seconds, and the change in capacitance before and after was measured.

Capacity change rate (%) = (capacity before immersion-capacity after immersion) / capacity before immersion x 100 (6) Long-term heat resistance After storage in an atmosphere at 150 ° C for 1000 hours, the change in withstand voltage before and after was measured. .

Dielectric strength change rate (%) = (Dielectric strength before storage−Dielectric strength after storage) / Dielectric strength before storage × 100 (7) Addition amount of inorganic filler The weight fraction was calculated using a thermogravimetric analyzer. It was determined from the residual amount after the film was treated at 1000 ° C. for 10 minutes in air.
The volume fraction was obtained by performing image processing on a photograph obtained by observing a cross section or a section of the film with an optical microscope or an electron microscope, thereby obtaining a ratio between a particle portion and a polymer portion.

(8) Average particle size of inorganic filler HORIBA, Ltd. centrifugal automatic particle size distribution analyzer (CAPA-50
0). The dispersant was measured by ultrasonication using water.

EXAMPLES Hereinafter, the present invention will be described with reference to Examples, but the present invention is not limited thereto.

Table 1 summarizes examples and comparative examples. All parts used below are parts by weight.

Example 1 Aramid A synthesized from 95 mol% of 2-chloro-p-phenylenediamine (CPA), 5 mol% of 4,4'-diaminodiphenyl ether (DAE) and 100 mol% of 2-chloroterephthalic acid chloride (CTPC) 100 parts of 5 wt% NMP (N-methylpyrrolidone) solution, 100 mol% of DAE and 100 mol% of CTPC
3 parts of a 15 wt% NMP solution of aramid B obtained from the above and 8 parts of barium titanate having an average particle diameter of 0.15 μm and a particle diameter of 30 μm or more having a ratio of 1.3 wt% were mixed at room temperature using a spiral stirring blade.
Stirred for hours. The resulting solution was cast on an endless metal belt and dried at 150 ° C. until it had self-supporting properties.After peeling off the belt and introducing into a water tank, desolvation was performed, and then drying and drying of water in a tenter. Heat treatment and cooling 3
A μm film was obtained. During this time, the film is MD
The film was stretched 1.1 times in the direction and 1.2 times in the TD direction in the tenter. The heat treatment was performed at 300 ° C. for 2 minutes. The properties of this film are shown in Table 1 and were very good.

Aluminum was vacuum-deposited on this film so that the surface resistance became 2Ω. At that time, it was vapor-deposited in a stripe shape with a margin running in the longitudinal direction.
The width of the margin part is repeated 1.0mm). Next, the whole width 5.0m with a margin of 0.05mm on the left or right obtained by slitting by inserting a blade in the center of the vapor deposition section and the center of each margin section
m tapes were superposed and wound two by two. At that time, the two films were wound while being shifted so that the vapor deposition portion protruded from the margin portion by 0.5 mm in the width direction.

Remove the core material from this roll and leave it at 180 ° C, 10kg /
Pressing was performed at a temperature and a pressure of cm ² for 5 minutes, and metallicon was sprayed on both end surfaces to form external electrodes. A lead wire was connected to the metallicon to obtain a wound capacitor (3.5 μF). The evaluation results of the solder resistance and the long-term heat resistance of this capacitor are shown in Table 1, and the capacitor had good capacitor characteristics.

Comparative Example 1 Except not adding the aromatic polyamide B of Example 1,
From the solution obtained by adjusting the ratio of aramid and barium titanate as in Example 1, a film was formed in the same manner as in Example 1 to obtain a 3 μm film, and further, in the same manner as in Example 1. When the capacitor was manufactured, the film was brittle and had poor handling properties, and had poor properties as shown in Table 1.

Comparative Example 2 Except that the aromatic polyamide A of Example 1 was not added,
From the solution obtained by adjusting the ratio of aramid and barium titanate as in Example 1, a film was formed in the same manner as in Example 1 to obtain a 4 μm film, and further, in the same manner as in Example 1. When the capacitor was manufactured, the characteristics were poor as shown in Table 1.

Example 2 Using the same aramid A, aramid B, and barium titanate as in Example 1, films having the ratios shown in Table 1 were produced, and a capacitor was produced in the same manner as in Example 1. As shown in Table 1, it had good characteristics.

Example 3 70 mol% of 2-chloroparaphenylenediamine, 4,4 '
-Aminoamide A 'obtained from 30 mol% of diaminodiphenyl sulfone, 100 mol% of 2,6-naphthylene dicarboxylic acid chloride, aramid B obtained in Example 1 and average particle diameters of 0.05 μm and 30 μm Using rutile-type titanium oxide containing no particles having the above particle size, a film having a ratio as shown in Table 1 was produced, and a capacitor was produced in the same manner as in Example 1. It had good properties as shown.

Continuation of the front page (51) Int.Cl. ⁶ identification code FI H01G 4/18 330 H01G 4/18 330A // B29K 77:00 B29L 7:00 C08L 77:10 (58) Fields surveyed (Int.Cl. ⁶ , DB name) H01B 3/30 C08J 5/18 B29C 55/02 H01G 4/18 330

Claims (2)

(57) [Claims] 1. A para-oriented aromatic polyamide A having a linear structure containing at least 60 mol% of a repeating unit represented by the formula (1) or (2), and a formula (3) or a formula (4) A film comprising an aromatic polyamide B having a structure in which a polymer structure containing a repeating unit represented by or more than 50 mol% is not linear, and an inorganic filler,
A high dielectric constant film comprising aromatic polyamide B in an amount of 2 to 40% by weight based on the total amount of aromatic polyamides A and B, and an inorganic filler in the film in an amount of 30% by weight or more. -(HN-Ar ₁ -NHCO-Ar ₂ -CO)-... (1)-(HN-Ar ₃ -CO)-... (2) (Even if Ar ₁ , Ar ₂ and Ar ₃ have the same composition, May be different,
A linear structure including at least one aromatic ring bonded to para and a naphthalene skeleton, and a linear polymer structure including one or more aromatic rings and orienting them are also included. Also, part of the hydrogen on these aromatic rings are halogen group, a nitro group, an alkyl group of C ₁ ~C _3, C ₁ ~
Including those substituted with substituents such as alkoxy groups C _{3. ) - (HN-Ar 4 -NHCO} -Ar 5 -CO) - ··· (3) - (HN-Ar 6 -CO) - ··· (4) (Ar 4, Ar 5, Ar 6 is an aromatic ring And a naphthalene skeleton, and the polymer structure is not linear.
Ar ₄ , Ar ₅ and Ar ₆ may be the same composition or different. However, if at least one of Ar ₄ and Ar ₅ does not have a linear structure, the other may have a linear structure. Also, part of the hydrogen on these aromatic rings are halogen group, a nitro group, an alkyl group of C ₁ -C _3, also those which are substituted with substituents such as alkoxy groups C ₁ -C ₃ Including. ) 2. A capacitor using the high dielectric constant film according to claim 1.