JP2002134353A - Film and capacitor suing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a film for a capacitor which has a thermal resistance at a high temperature of around 230 deg.C and is superior in solder resistance for high-temperature usage. SOLUTION: This film is made of polyester (A) and polyether imide (B), and a ratio M/P of a quantity M of total inorganic composition to a content P of phosphorous is 2.0 or smaller, and an extrapolation glass transition start temperature is in the range of 90 deg.C or higher and 130 deg.C or lower, the surface roughness Ra is 0.02 μm or larger and 0.08 μm or smaller, and a heat shrinkage ratio at 230 deg.C-30 min is 4% or lower.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film for a capacitor, and more particularly to a film made of polyester and polyetherimide and a capacitor using the same.

[0002]

2. Description of the Related Art Capacitors in which a biaxially stretched polyester film is used as a dielectric layer and metal electrodes formed on the surface thereof are used as electrodes are widely used. In recent years, there has been a demand for increasing the operating temperature of a capacitor.
Japanese Patent No. 1070 discloses a polyester film for a capacitor which is excellent in heat resistance and uses a film made of a blend of different kinds of polyesters.

Japanese Patent Application Laid-Open No. 57-187327 discloses that a capacitor having excellent frequency characteristics and soldering resistance is obtained by using biaxially stretched polyphenylene sulfide as a dielectric layer.

[0004]

However, the conventional polyester film has a high heat shrinkage at around 230 ° C., and the deformation of the element causes a variation in capacitance and a decrease in insulation resistance.
On the other hand, the polyphenylene sulfide film has a disadvantage that the dielectric breakdown voltage is inferior.

An object of the present invention is to improve the drawbacks of the conventional polyester film and polyphenylene sulfide film, and to provide a film having a high dielectric breakdown voltage and excellent solder resistance.

[0006]

SUMMARY OF THE INVENTION The present invention relates to a film comprising a polyester (A) and a polyetherimide (B), wherein a ratio of the total amount M of the inorganic component to the amount P of the phosphorus component in the film. A certain M / P is 2.0 or less, extrapolation glass transition onset temperature is 90 ° C. or more and less than 130 ° C., surface roughness Ra is 0.02 μm or more, less than 0.08 μm, heat at 230 ° C. for 30 minutes A film for a capacitor, wherein the shrinkage ratio is 4% or less.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The polyester (A) used in the present invention is not particularly limited, but preferably has an ethylene terephthalate unit, and more preferably has at least 70 mol% or more of an ethylene terephthalate unit. is there.

The polyetherimide (B) used in the present invention
Is a polymer containing an aliphatic, alicyclic or aromatic ether unit and a cyclic imide group as repeating units, and is not particularly limited as long as it is a polymer having melt moldability. As long as the effects of the present invention are not impaired, the main chain of the polyetherimide contains a cyclic imide, a structural unit other than an ether unit, for example, an aromatic, aliphatic, alicyclic ester unit, or an oxycarbonyl unit. May be. In the present invention, a polyetherimide having a glass transition temperature of 350 ° C. or lower, more preferably 250 ° C. or lower is preferable, and 2,2-bis [4- (2,3-dicarboxyphenoxy) phenyl] propane dianhydride and m A condensate with phenylenediamine or p-phenylenediamine is
It is most preferable from the viewpoint of compatibility with polyester, cost, melt moldability and the like. This polyetherimide is
The product is manufactured by eral Electric and is known under the trade name of ULTEM 1000 series.

In the present invention, the mixing ratio of the polyester and the polyetherimide is preferably 95 to 6%.
5% by weight and 5-35% by weight of polyetherimide.
More preferably, the content is 90 to 80% by weight of polyester and 10 to 20% by weight of polyetherimide. When the content of the polyetherimide is less than 5% by weight, heat resistance in a high-temperature region is inferior, and the withstand voltage at 125 ° C. may decrease.
If it exceeds 35% by weight, film tearing will increase, which may lead to a decrease in productivity, an increase in product price, and a loss in product value.

The phosphorus component in the present invention is a compound containing phosphorus, and phosphoric acid is particularly preferably used. The inorganic component is an inorganic compound containing an alkali metal or an alkaline earth metal. The amount P of the phosphorus component and the amount M of all the inorganic components are quantified by X-ray fluorescence analysis as described later.

M / P is 2.0 or less, preferably 1.5 or less. If the M / P exceeds 2.0, the amount of the phosphorus component with respect to the metal component in the film is small, and the leakage current increases due to the influence of the ions in the film, and the insulation resistance at high temperatures is reduced. The lower limit is not particularly limited, but is usually 0.5. If it is less than 0.5, the amount of the inorganic component tends to be small, and the transesterification reaction is inferior, and the efficiency of polyester production is deteriorated.

M / P can be set to a desired value by adjusting the amounts of the inorganic component and the phosphorus component. For example, M / P is controlled to 1.0 or less by using 0.05 to 0.12% by weight of calcium acetate as an ester exchange catalyst as an inorganic component and 0.02 to 0.05% by weight of phosphoric acid as an additive. be able to. In this case, M / P
Can be controlled by lengthening the time during the transesterification reaction, increasing the temperature, and increasing the reduced pressure during the polycondensation reaction.

The extrapolated glass transition onset point of the film of the present invention is 90 ° C. or higher and lower than 130 ° C., preferably 9 ° C.
5 ° C. or more and less than 120 ° C. If the extrapolated glass transition onset point is less than 90 ° C., the dielectric loss at 100 ° C. or higher is high, and there is a problem that dielectric breakdown and element deformation at high temperatures occur.
On the other hand, when the temperature is higher than 130 ° C., the film is frequently broken during film formation, and stable production cannot be performed.

The film of the present invention has a surface roughness Ra of 0.0
2 μm or more and less than 0.08 μm, preferably 0.1 μm or less.
It is not less than 03 μm and less than 0.06 μm. Roughness is 0.0
If the thickness is smaller than 2 μm, the film will not slide smoothly, and wrinkles are likely to occur, causing not only a decrease in workability of winding the element but also a low-pressure breakdown in the element. When the thickness is 0.08 μm or more, the surface is rough, the capacitance of the capacitor element is small, the variation is large, and a capacitor product cannot be manufactured stably.

The heat shrinkage of the film of the present invention at 230 ° C. for 30 minutes is 4% or less, preferably 2.5% or less. If the heat shrinkage ratio is more than 4%, the chip capacitor products without lead wires will be deformed at the time of high temperature treatment around 230 ° C., and cannot be used by directly soldering to the substrate due to a variation in capacity.

In the film of the present invention, a compatibilizer, inorganic and organic particles, and other various additives such as an antioxidant, an antistatic agent and a crystal nucleating agent are added to such an extent that the effects of the present invention are not impaired. A small amount can be added.

Next, a preferred method for producing the film of the present invention will be described. However, it is needless to say that the present invention is not limited to this production method.

A polyester (A) containing ethylene terephthalate as a main component and hereinafter referred to as General Elect
This will be specifically described by taking a film made of ULTEM 1010 manufactured by Ric Corporation as an example, but the manufacturing method differs depending on the raw materials used.

Pellets of polyethylene terephthalate (hereinafter abbreviated as PET) obtained by ordinary polycondensation (A)
(IV = 0.85) and Ultem 1010 (IV = 0.6
88) The pellet (B) is mixed at a certain ratio,
The mixture is supplied to a vent-type twin-screw kneading extruder heated to 70 to 300 ° C. and melt-kneaded to obtain a blend chip. Shear rate at this time is preferably 50~300sec ^-1, more preferably 100~200sec ^-1. The shear rate during kneading is an important factor in the compatibility of the blend chips. PET (A) and Ultem 1 in the above-mentioned kneading operation
The weight fraction (A / B) of the 010 (B) blend is 5 /
From 95 to 95/5, from the viewpoint of melt-kneading properties and thermal decomposition, 20/80 to 50/50 is more preferable. In the present invention, a method of first preparing a blend chip with a high weight fraction of Ultem 1010 (B) and diluting the chip with PET (A) is effective in obtaining a high quality film.

Next, the P obtained by the above pelletizing operation
Using a blend chip composed of ET (A) and Ultem 1010 (B), PET (A) and Ultem 1010
An appropriate amount was mixed so that (B) became 90/10 by weight fraction, and vacuum-dried at 180 ° C. for 3 hours or more. Then, these were put into an extruder, melt-extruded at 280 to 320 ° C., passed through a fiber sintered stainless steel metal filter, and then discharged in a sheet form from a T-die, and the sheet was heated to a surface temperature of 10 to 70 ° C. And cooled and solidified to obtain an unstretched film of 40 to 160 μm.

Next, this unstretched film is subjected to a total of 16
Biaxial stretching and heat treatment are performed at double the area magnification. As a stretching method, a known sequential biaxial stretching method or simultaneous biaxial stretching method can be used. In the present invention, a method such as a normal biaxial stretching method in which the film is stretched once in the longitudinal direction and the transverse direction once, a re-longitudinal stretching method, a re-longitudinal re-lateral stretching method, or the like can be used. In each stretching such as longitudinal stretching, transverse stretching, and simultaneous biaxial stretching, a so-called multi-stage stretching method in which a stretching operation performed in at least one direction is divided at least twice or more and stretched may be applied. Hereinafter, an example in which a film is obtained by applying transverse stretching after ordinary longitudinal stretching will be described. In the following production method, Tg is the glass transition temperature of the unstretched film, and Tm is the melting temperature of the unstretched film.

First, the unstretched film is prepared from (Tg-25)
(Tg + 50) (° C.), more preferably (Tg−2)
0) to (Tg + 30) (° C.), and heated by a group of heating rolls in the range of 2.0 to 5.0 times, preferably in the longitudinal direction,
The film is stretched 2.5 to 3.5 times and cooled with a group of cooling rolls at 20 to 50 ° C. Next, guide the film to the tenter,
The stretching ratio in the transverse direction is preferably 2.0 to 6.0 times, more preferably 3.5 to 4.5 times, and (Tg-25) to (Tg-25).
(g + 50) (° C.). Then, the biaxially stretched film is cooled to room temperature while relaxing under tension or 1 to 20% in the width direction to obtain the film of the present invention.

In order to manufacture the capacitor of the present invention, first, the biaxially oriented film obtained as described above is prepared in the following manner.
mm to obtain a product roll having a length of 3000 to 10000 m. Next, the metal roll is vapor-deposited on a film surface under vacuum so as to have a film resistance of 1.5 to 3.5 Ω / port. As shown in FIG. 1, a metallized film 3 in which a metal film 1 is formed on almost one side and a non-metal film 2 is formed on one end of the film, and the non-metal film 2 is formed on one end of the film. They are stacked so that they are alternately located at opposite ends, and electrodes 4 are formed at both ends.

The laminated film capacitor is prepared by heat-pressing the above-mentioned metallized film in a band shape with a press, and then cutting the strip-shaped laminated body into chips with a cutter.
It is manufactured through a process of forming electrodes such as metallikon on both ends. Multilayer capacitors are generally effective for miniaturization.However, there are many cases where the insulation resistance drops and the breakdown voltage varies due to the effects of heat in the pressing process and jagged edges at the time of cutting. Of heat shrinkage and Tg
By raising the starting temperature, a stable capacitor was obtained.

The capacitor has stable electric characteristics,
Due to miniaturization, the application to communication equipment is expanding.

[Method of measuring physical properties and method of evaluating effects]
The method of measuring characteristic values and the method of evaluating effects are as follows.

(1) M / P Automatic fluorescent X-ray analyzer (RIX) manufactured by Rigaku Denki Kogyo
3000), place the film on the sample plate,
The strength of each element is determined from the measurement area of 0 mmφ, and the amount of the inorganic component of each element is quantified from the calibration curve.

[0028]

(Equation 1) M / P was determined by the following formula.

(2) Extrapolated glass transition onset temperature Specific heat measurement was carried out by a pseudo-isothermal method using the following apparatus and conditions.
It was determined according to JIS K7121. Apparatus: Temperature modulation D manufactured by TA Instrument
SC Measurement conditions: Heating temperature: 270 to 570K (RCS cooling method) Temperature calibration: Melting point of high-purity indium and tin Temperature modulation amplitude: ± 1K Temperature modulation cycle: 60 seconds Heating step: 5K Sample weight: 5mg Sample container: Aluminum Open container made of aluminum (22 mg) Reference container: Open container made of aluminum (18 m
g).

(3) Surface Roughness According to JIS B0601-1976, the cut-off was set to 0.25 mm.

(4) Heat shrinkage rate According to JIS C2318, a heat shrinkage rate of 3 at a temperature of 230 ° C. ± 5 ° C.
Measure the amount of thermal deformation in 0 minutes and calculate the following equation

[0032]

(Equation 2) It was expressed by.

(5) Variation in element capacitance 100 capacitors of 0.5 μF were prepared, and were researched by Soken Co., Ltd.
The capacitance was measured at a frequency of 60 Hz and a voltage of 100 V using a Schering bridge of No. The average value C and the standard deviation σ were calculated, and (σ / C) × 100 was defined as the variation in capacity. Needless to say, the smaller the variation, the better it was.

(6) Insulation Resistance The insulation resistance of a 0.5 μF capacitor at a voltage of 100 V was measured using a super insulation meter manufactured by Toa Electric Corporation.

(7) Dielectric breakdown voltage A capacitor having a capacity of 0.5 μF was prepared, and a voltage of 100 v / sec was obtained.
DC is applied at a step-up speed of c, and the voltage when the capacitor element is broken is defined as the breakdown voltage.

(8) Dispersion of dielectric breakdown voltage 100 capacitors having a capacitance of 0.5 μF were prepared, and 100
The dielectric breakdown voltage of the capacitor element is measured at a boosting rate of v / sec. The average value V and the standard deviation σ were calculated, and (σ / V) × 100 was defined as the variation of the dielectric breakdown voltage. Needless to say, the smaller the variation is, the better it is.

[0037]

EXAMPLES The present invention will be described based on examples and comparative examples.

Example 1 Dimethyl terephthalate and ethylene glycol were charged into a reactor by a known method, and 0.09% by weight of calcium acetate was added.
Was subjected to a transesterification reaction as a transesterification catalyst, and then aggregated silica manufactured by Fuji Devison was added as an additive to 0.0
PET (P) containing 7% by weight and 0.03% by weight of phosphoric acid
ET) pellets (50% by weight) and General E
Polyetherimide Ultem 10 manufactured by Electric
10 (50% by weight) was fed to a vented twin-screw kneading extruder of the same direction rotating at 290 ° C. and melt-extruded at a shear rate of 120 sec ⁻¹ and a residence time of 2 minutes. % Of a blended chip was obtained. Next, blend chip 2 obtained by the pelletizing operation
0 parts by weight and 80 parts by weight of a PET chip having an intrinsic viscosity of 0.615 were vacuum-dried at 180 ° C. for 3 hours, then put into an extruder, melt-extruded at 285 ° C., and sintered with a fiber sintered stainless metal filter (10 μm filter). G) within 10 seconds ^-1
, And discharged in a sheet form from a T-die. The sheet was closely adhered to a cooling drum having a surface temperature of 25 ° C. and solidified by cooling to obtain a 56 μm unstretched film.

Subsequently, the film was stretched at a temperature of 110 ° C. in the longitudinal direction of the film at a magnification of 4.0 times using a longitudinal stretching machine composed of a plurality of heated roll groups. After that, a stretching temperature of 100
The film was stretched in the transverse direction at 4.0 ° C. at a stretching ratio of 4.0.
Thereafter, a heat treatment was performed while relaxing at 5% at a temperature of 240 ° C. to obtain a biaxially stretched film having a thickness of 3.5 μm.

This biaxially stretched film was cut into a width of 500 mm, and a product roll having a length of 10,000 m was collected. The product roll was deposited on a film surface under a vacuum so that Al metal was deposited to a film resistance of 3 Ω / port to form a metallized film.

This Al metallized film was cut to a width of 15 mm to obtain a vapor-deposited product. A total of 295 layers of the two deposited films were laminated to form a band-shaped laminate. The heat press was performed at a temperature of 175 ° C. and a pressure of 60 kg / cm ² . The strip-shaped laminate was cut into a width of 5 mm to obtain a chip capacitor of 0.5 μF.

The capacitor element was subjected to a heat treatment in an oven heated to 230 ° C. for 15 minutes, and then the capacitance, insulation resistance and breakdown voltage of the element were evaluated. As shown in Table 1, M /
P is 0.9, extrapolated glass transition onset temperature is 105 ° C., film surface roughness is 0.033 μm, capacity variation is small, insulation resistance is 3.5 × 10 ⁶ MΩ, and withstand voltage is 1 .44 kv high quality capacitor.

Example 2 The procedure of Example 1 was followed except that 40 parts by weight of the blended chips and 60 parts by weight of the PET chips were mixed and the content of polyetherimide was increased to 20% by weight. As shown in Table 1, the result was a high quality film with small capacity variation, high insulation resistance and excellent withstand voltage.

Example 3 In order to change the surface shape of the film, the same procedure as in Example 1 was carried out except that the amount of the aggregated silica was increased to 0.15% by weight and the film having a roughness of 0.048 μm was used as an additive. The results were high quality capacitors as shown in Table 1.

Comparative Example 1 The procedure of Example 1 was repeated except that a raw material of 100% PET was used. As shown in Table 1, the extrapolated Tg onset temperature was low, the heat shrinkage was high, the capacity variation was large due to the deformation of the element, and the insulation resistance and withstand voltage were low.

Comparative Example 2 Example 1 except that the content of polyetherimide was 50% by weight.
According to. As shown in Table 1, the extrapolated Tg onset temperature was 135 ° C., but the film was frequently broken, and a stable film could not be formed, resulting in poor productivity.

Comparative Example 3 The procedure of Example 1 was repeated except that the aggregated silica was reduced to 0.02% by weight as an additive, and a film having a smooth surface having a surface roughness of 0.01 μm was used. As shown in Table 1, the workability of winding the element was poor due to poor slip, the insulation resistance of the element was reduced due to wrinkles, abnormal breakdown at low voltage occurred, and the withstand voltage was varied.

Comparative Example 4 The procedure of Example 1 was followed except that PET was added with 0.06% by weight of magnesium acetate as a transesterification catalyst and 0.026% by weight of trimethylphosphoric acid as an additive. As shown in Table 1, the M / P was as large as 2.7, the insulation resistance at high temperatures was reduced, and the withstand voltage characteristics of the device were low.

[0049]

[Table 1]

[0050]

The film for a capacitor of the present invention has excellent heat resistance and can obtain a chip capacitor having excellent capacitor characteristics. According to the present invention, a product can be miniaturized, and the industrial value is extremely high.

[Brief description of the drawings]

FIG. 1 shows one embodiment of the capacitor of the present invention using a metallized film.

[Description of Signs] 1 Metal film 2 Non-metal film 3 Metallized film 4 Electrode

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) H01G 4/18 330 H01G 4/18 330A 4/24 321C F term (Reference) 4F071 AA43 AA46 AA60 AA86 AF27Y AF61Y AH12 BA01 BB06 BB08 BC01 BC16 4J002 CF001 CF061 CH002 CM042 GQ00 5E082 AA01 AB03 BB05 BB10 BC23 EE07 EE08 EE24 EE37 FG06 FG22 FG36 FG38 FG39 FG48 FG54 LL02 MM22 MM24 PP03 PP04 PP06 PP10

Claims (5)

[Claims] 1. A film comprising a polyester (A) and a polyetherimide (B), wherein M / P, which is the ratio of the amount M of all inorganic components to the amount P of phosphorus components in the film, is 2.0. Hereinafter, the extrapolated glass transition onset temperature is 90
° C or more and less than 130 ° C, and the surface roughness Ra is 0.02
A film for a capacitor, characterized in that the heat shrinkage at 230 ° C. for 30 minutes is 4% or less. 2. An extrapolated glass transition onset temperature of 95 ° C. or higher,
The film for a capacitor according to claim 1, wherein the temperature is lower than 20 ° C. 3. A capacitor comprising a metallized film provided with a metal layer on at least one surface of the film according to claim 1. 4. A chip capacitor using the film according to claim 1. 5. The chip capacitor according to claim 4, which is used for a telephone exchange or a communication device.