JPS611008A - Condenser - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a capacitor using a poly-p-phenylene sulfide film as a dielectric.

[Conventional technology]

Conventionally, plastic film capacitors with excellent electrical characteristics have been used in circuits that require high precision, such as time constant circuits. Films such as polyethylene terephthalate (PET), polypropylene (PP), polystyrene (PS), and polycarbonate (PC) are used as dielectrics for such capacitors.

On the other hand, conventionally known heat-resistant films include polyamide films and aromatic polyamide films.

[Problems to be solved by the present invention]

To mount circuit components such as capacitors on a circuit board,
Soldering is generally used.

Conventional plastic film capacitors lack heat resistance, and the heat of the melted solder during soldering causes a significant change in capacitance and a drop in insulation resistance.

On the other hand, a capacitor using a conventional heat-resistant film as a dielectric may be considered, but this would have poor electrical characteristics and lose its characteristics as a plastic film capacitor.

Therefore, the present inventors focused on poly-p-phenylene sulfide as a dielectric material for such a capacitor.

Poly-p-phenylene sulfide is 'Ryoton
"It is commercially available as a material polymer for injection molding and coatings by Phillips Corporation (USA) under the trade name ``. This is too low, and films made of these materials are too brittle to be practical.Therefore, capacitors using poly-P-phenylene sulfide films as dielectrics do not yet exist, and even if they were attempted to be made, the films would be too brittle. , I can't stop processing it.

In view of this situation, the present inventors have conducted research on obtaining a practical film from poly-p-phenylene sulfide, and have arrived at a biaxially oriented poly-p-phenylene sulfide film that has excellent heat resistance and is transparent. The object is to provide a capacitor using this as a dielectric.

SUMMARY OF THE INVENTION An object of the present invention is to provide a plastic film capacitor that has heat resistance and is less likely to change capacitance or reduce insulation resistance due to solder heat during mounting.

[Means for solving problems]

The present invention is a biaxially oriented film made of poly-p-phenylene sulfide containing 90 mol% or more of repeating units <(〒E)-S-), which has a melt viscosity at 300°C at a shear rate of 200 (seconds). -1, 100 to 600,000 poise, and density at 25℃ is 1.330~'
The invention features a capacitor whose dielectric is a biaxially oriented poly-p-phenylene sulfide film in the range of 400.

The poly-p-phenylene sulfide film of the present invention is
It is possible to reduce the heat shrinkage rate to 1.0% or less in at least one direction at 200°C for 10 minutes under no tension, compared to the heat shrinkage rate of polyethylene terephthalate biaxially oriented film of 3% or more under the same conditions. Therefore, it is a practical film that has extremely excellent dimensional stability due to heat, and is also extremely excellent in terms of mechanical strength and transparency.

In the present invention, poly-p-phenylene sulfide is a polymer in which 90 mol% or more consists of the structural unit (■-8-), and if it is less than 90 mol%, the crystallinity of the obtained film will decrease. However, heat resistance, mechanical properties, etc. deteriorate, heat shrinkage increases, capacitance changes increase during soldering, insulation resistance decreases, and the object of the present invention cannot be achieved.

It should be noted that the polymer may contain copolymerized units as long as it is less than 10 mol % of the structural units of the polymer. Such copolymerized units include, for example, trifunctional units (e.g. A]Σ)
-so-(strained I)-3-), ketoneThe synthesis method of poly-p-phenylene sulfide consisting of such a structural unit includes (1) reaction of p-dihalobenzene and sulfur, (2) p-
There are methods such as the reaction of dihalobenzene with an alkali sulfide or an alkaline earth metal sulfide, and (3) the reaction of p-dithiophenol with an inorganic alkali. It's simple. A temperature of 200 to 350° C. is applied as the polymerization conditions, and the pressure within the polymerization system and the polymerization time are appropriately determined depending on the type of catalyst used and the desired degree of polymerization. There is no problem in adding a polymer swelling agent, anti-degradation agent, etc. to the polymerization system.

The poly-p-phenylene sulfide in the present invention is adjusted to have a melt viscosity at 300° C. of 100 to 600,000 poise when measured at a shear rate of 200 (sec) −1 as a polymer. Melt extrusion molding of materials with a melt viscosity outside of this range is difficult; furthermore, if the viscosity is too low, it will be brittle and a practical film cannot be obtained, and if the viscosity is too high, moldability such as flow characteristics will deteriorate. .

Furthermore, when poly-p-phenylene sulfide is heated at high temperatures, particularly in air, crosslinking, branching, and chain rearrangement occur, resulting in a change to a polymer structure other than a linear polymer structure.

Highly cross-linked, branched, etc. polymers have the disadvantage of poor flow properties during melting, poor stretchability after film formation, and poor surface properties. Therefore, the poly-p-phenylene sulfide used in the present invention preferably has a linear polymer structure, but it also contains a polymer with a cross-linked or branched structure in an amount less than 10 mol%, especially less than 1 mol%. However, it is not a problem, as it may give more favorable results in cases such as viscosity adjustment.

The biaxially oriented poly-p-phenylene sulfide film in the present invention has a density of 1°330 to 1.4 at 25°C.
It is 00. Films with a density of less than 1.330 have poor mechanical properties and tend to become cloudy and brittle when heated, while films with a density of more than 1.400 are inflexible and more difficult. It is easy to tear,
Not practical. It should be noted that the value of density in the present invention is, of course, for poly-p containing no substances mixed as necessary.
-Values for phenylene sulfide only. Furthermore, the melt viscosity of the film of the present invention is almost unchanged before and after the biaxial part surface, and the shear rate at 300'C is 200 (seconds).
-1 is in the range of 100,000 to 600,000 poise.

The above-mentioned film of the present invention has extremely excellent transparency in a state in which substantially no other substances are mixed, and the haze when the film has an average thickness of 25 μm is 20% or less,
Furthermore, it is characterized by being extremely transparent for this type of film, with a content of less than 10% and 5%.

The capacitor of the present invention uses the above biaxially oriented poly-p-phenylene sulfide film as a dielectric.

Next, a method for manufacturing a capacitor according to the present invention will be illustrated.

First, the poly-p-phenylene sulfide of the present invention is molded in a molten state using a press or a die, and then rapidly cooled to form a non-quality film.

At this time, by rapidly cooling at a cooling rate of at least 5° C./second or more, a non-quality transparent film with a crystallinity of 15% or less can be obtained. If the cooling rate is slow, large crystal growth will proceed, causing opacity and embrittlement.

This non-quality transparent film is stretched simultaneously or sequentially at 80 to 120°C at an area magnification of 3 times or more, preferably 4 times or more, by a method such as rolling or stretching.
It is oriented along two axes. Such a biaxially stretched film also has a density (
25°C) is less than 1.330, it is unstable to heat and easily becomes cloudy and brittle. For example, when exposed to temperatures higher than the above-mentioned stretching temperature, it undergoes significant heat shrinkage and further becomes opaque and brittle. Therefore, capacitors using this film as a dielectric have the same drawbacks as conventional capacitors.

After the above-mentioned biaxial orientation, the film used in the present invention is subjected to 1
Heat set at 80°C to the melting point of the polymer (approximately 300°C). Such heat setting substantially increases the density of the biaxially oriented film to a range of 1.330 to 1.400. The heat setting time varies from seconds to minutes depending on the desired density, e.g.
A heat setting time of about seconds to 10 minutes may be employed.

The biaxially oriented poly-p-phenylene sulfide film thus obtained has the excellent feature that it does not exhibit any cloudiness or decrease in brittleness even when heated to near the melting point of the polymer. Such a film has a planar orientation coefficient of at least 0.50 or more, preferably 0.75 or more when measured by X-rays. Note that other polymers or inorganic fillers may be mixed into the film as necessary.

A capacitor element is formed by a well-known method using the thus obtained biaxially oriented poly-p-phenylene sulfide film as a dielectric and a metal film or the like as an electrode.

For example, when metal foil is used as an electrode, the shredded film and metal foil are overlapped and wound to form a capacitor element. In addition, when a metal thin film is used as an electrode, the metal thin film is formed on the film in advance by vapor deposition or the like and then wound or laminated to form a capacitor element.

If necessary, the above-mentioned capacitor element is subjected to end face conductive treatment, lead wire (or electrode extraction metal fitting) attachment, outer jacket formation, etc. to obtain the capacitor of the present invention.

〔Effect of the invention〕

The capacitor of the present invention has the above configuration, and as a result,
It has better electrical properties than conventional film capacitors and is extremely heat resistant, making it an excellent choice when mounting capacitors on circuit boards, etc., with less change in capacitance and less drop in insulation resistance due to solder heat. It became a capacitor.

Next, a method for measuring the characteristics in the present invention will be described.

The method for measuring melt viscosity in the present invention is by using a rotary rheometer or a flow tester, and it is convenient to measure with a Koka type flow tester at 300° C. and a shear rate of 200 (seconds) −1. The increase or decrease in melt viscosity of the polymer of the present invention can be adjusted as appropriate by the molecular weight and the amount of branching and crosslinking; that is, the higher the molecular weight and the more branching and crosslinking, the higher the viscosity of the polymer.

The density in the present invention is determined by a density gradient tube using an organic solvent or an aqueous solution of an inorganic salt. In the present invention, an aqueous solution of an inorganic salt consisting of lithium bromide/water was measured using a density gradient tube at 25°C and expressed as a value of 1.

Next, the degree of plane orientation of the film in the present invention is determined by the refractive index and
It is shown as a numerical value measured using a line polar diagram.

In the measurement, a polar figure was created from crystal peaks existing at 2θ-20 to 21°, and the degree of plane orientation was determined.

The capacitance of the capacitor in the present invention can be quickly measured using an automatic capacitance bridge at 25°C.
, 1k)-1z. At the same time, the dielectric loss tangent (tan
δ) was also measured.

Next, the present invention will be explained by examples.

Example 1 1 mol of sodium sulfide nonahydrate, 0.1 sodium hydroxide
4 mol, lithium acetate dihydrate 0.90 mol, N-methylpyrrolidone 400. M and C were placed in a stirred autoclave and heated to 20'O<0>C in a nitrogen stream to drive off water. Next, 1.02 mol of p-dichlorobenzene, 1,2.
Add 6 moles of 4-trichlorobenzene O, add 1 N to the system, and pressurize the system to 41 (970 m2), then reduce the content to 27
The mixture was heated to 0°C and polymerization was carried out with stirring for 3 hours. After polymerization, the system was immersed in water and the polymer was filtered off, washed and dried to obtain a powdered polymer.

In order to find out the melt viscosity of this polymer, we used a high-down type flow tester (manufactured by Shimadzu Corporation) and measured 1.0mmφX10n+m.
When measured at 300°C using a nozzle of

This polymer was press-molded at 300'C and then immersed in liquid nitrogen within 5 seconds to obtain a transparent film with a density of 1.320. The density was measured at 25°C using a density gradient tube using a lithium bromide-water system.

Transfer this film to a film stretcher (T.

v, +-ong) at 90°C at r3. OX3.
Biaxial stretching was performed at 0x rotation. The film density after stretching was 1.320, which was the same as before stretching.

After further stretching, the film was fixed on a metal frame and
By heating at 0°C for 20 seconds, a transparent (turbidity: 3°0%) 10μ film with a density of 1.357 was obtained.

The turbidity can be calculated, for example, using an integrating sphere haze meter manufactured by Nippon Seimitsu Kogaku Co., Ltd., as follows: haze (%) - [(Td/Tt) - (Tf/100)) xl 00 . Here, Td=quantity of scattered light, T
t - Total transmitted light, Tf - Instrument factor.

In addition, other physical properties of this film include plane orientation coefficient o, so
o, 200°C, io minute thermal shrinkage rate 0°50%, strong a
13, Okg/mm2, Y>'j rate is 390! +
/mH2, and elongation was 60%.

This film was cut out to a width of 5.0 mm and a length of 20 On+n+, and one side of the film was vapor-deposited to a width of 4.0 mm, leaving an undeposited part of 0.5 mtn width at one edge in the longitudinal direction.

The capacitor of the present invention is obtained by wrapping two layers of this vapor-deposited film, applying conductive treatment to both end faces, welding an electrode lead-out metal fitting, and then transfer-molding an epoxy resin on top of it to provide an outer cover. (Capacitor No. 1
).

The characteristics of this capacitor are shown in Table 1.

Comparative Example 1 A biaxially oriented polyethylene terephthalate film with a thickness of 10 μm was prepared by a conventional method, and Example 1 was prepared from this film.
A capacitor was created in the same manner as (capacitor N00)
2).

The characteristics of this capacitor are shown in Table 1.

Note that the solder heat resistance test shown in Table 1 was conducted by immersing the sample in a 250° C. solder bath for 10 seconds.

Further, the capacitance change rate is calculated from the initial capacitance Co and the capacitance C after the solder heat resistance test using the following equation.

Capacity change rate (%) = 100 (C-Co)/C
.

It can be seen from Table 1 that the capacitor of the present invention has excellent heat resistance, and the change in capacitance before and after soldering and the decrease in insulation resistance are extremely small.

Claims (1)

[Scope of Claims] A biaxially oriented film made of poly-p-phenylene sulfide containing 90 mol% or more of repeating units (▲There are mathematical formulas, chemical formulas, tables, etc.▼), wherein the melt viscosity at 300°C is below the shear 100 to 600,000 poise at a speed of 200 (seconds)^-^1, and the density at 25°C is 1.330 to 1.
．． A capacitor whose dielectric is a biaxially oriented poly-p-phenylene sulfide film in the range of 400°C.