JPS62198111A - Metal evaporated film and capacitor - 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 (a) Field of Industrial Application The present invention relates to a metal-deposited film with improved adhesion between a metal-deposited metal and a plastic film, and a capacitor using such a film.

BACKGROUND OF THE INVENTION The use of plastic films coated with metal vapor deposition is very frequently used in packaging or capacitor applications.

As such a vapor-deposited film, a polyethylene terephthalate film or a polypropylene film vacuum-covered with A1, Zn, etc. is often used. In particular, in the case of polyolefin films, in order to impart chemical affinity between the deposited metal and the polymer, it is common to perform corona discharge treatment on the film and then deposit the metal (Japanese Patent Publication No. 40-7393 etc).

Also known as film capacitors are those in which an element is manufactured by winding two layers of the above vapor-deposited film, and those in which a large number of vapor-deposited films are piled up and then cut into chips. In addition, in order to suppress changes in capacitance (ΔC), capacitors with a special structure, such as forming a semiconducting layer on the edge of a metal vapor-deposited electrode, are also commercially available (Japanese Patent Laid-Open No. 50-85860, JP-A-50-85861>.

Problems to be Solved by the Invention However, many plastic films have low surface tension and therefore have poor vapor deposition properties. In particular, when metal vapor deposition is performed on polyolefins that do not contain polar groups, the vapor-deposited film easily peels off because there is no chemical affinity between the vapor-deposited metal and the polymer. Therefore, such films are sometimes subjected to corona discharge treatment, but in such corona discharge treatment, charge injection occurs because a high electric field is applied to the film, especially for polymers such as polyolefins, which have a large specific volume resistivity and are nonpolar. The injected charge cannot be easily removed even if a static elimination process is applied, and the material becomes an electret state. The film in the electret state has problems such as attracting dust in the air.
Due to the heat applied during metal deposition, charges are released and a discharge phenomenon occurs, which can lead to uneven deposition.

Furthermore, in the corona discharge treatment, since the polar groups formed on the surface layer have high mobility, the treatment effect decreases over time, and usually loses its effect after about 3 months. In addition, in recent years, the speed and width of the film forming process has increased, resulting in non-uniformity in the corona discharge treatment, resulting in weak adhesive strength between the metal and the film and non-uniform deposited films. .

Further, in a fully evaporated capacitor, as described above, a phenomenon occurs in which the capacitance gradually decreases when an alternating current is applied. This is because the deposited metal corrodes and becomes an oxide due to the corona discharge that tends to occur at the edges or peaks of the fully curved evaporation film, resulting in a reduction in the effective electrode area. The recent increase in the withstand voltage of capacitors is promoting this phenomenon, and various countermeasures are being considered, but the technique described above, which forms a semiconducting layer on the edge of a metal vapor-deposited electrode, causes ohmic loss, etc. However, there was a drawback that the dielectric loss was extremely large. Furthermore, the increase in cost due to the formation of the semiconductor layer was also a problem that could not be ignored.

The present invention aims to eliminate the drawbacks of such metallized films and capacitors using the same, and to provide a vapor-deposited film with high uniformity and adhesion, and a capacitor with improved electrical properties.

29 Means for Solving the Problems The present invention provides at least one side of the plastic film,
Melting start temperature is 25-900℃ and melting end temperature is 100℃
℃ or higher, and the 1 and 2 polybutadiene layers are provided, and the 1
．． The present invention relates to a metal vapor deposited film characterized in that a fully vaporized layer is provided on the surface of a polybutadiene layer, and a capacitor using the same.

In the present invention, the plastic film is a film made of polyolefin such as polyethylene, polypropylene, polynisder, polyamide, etc., and is not particularly limited, but among these, polyolefin film, i.e., polyethylene film, In the case of a polypropylene film, etc., it is preferable because it has strong adhesive strength with 1,2 polybutadiene (hereinafter referred to as 1.2 PBD and 108V), which will be described later. Furthermore, for capacitor applications, polypropylene films are particularly preferred from the viewpoint of electrical properties and thermal stability. The polypropylene film mentioned here is mainly composed of polypropylene, and may be a copolymer with comonomers such as ethylene and butene, or a blend with these polymers, but the isotactic index (II) is 92. % or more, more preferably 95%
The above is preferable from the viewpoint of increasing the dielectric breakdown voltage.

In addition, the intrinsic viscosity [η] should be 1.3 to 2.8 dD,/g, more preferably 1.7 to 2.5 dQ/c+, in order to improve the dielectric breakdown voltage and film formability.

Further, the orientation of the film may be selected from non-oriented, uniaxially oriented, or biaxially oriented depending on the application, but biaxially oriented is preferable from the viewpoint of mechanical properties and dielectric breakdown properties, and roughly 211
In the case of 'lll orientation, the plane orientation is 5X1o-3 to 25X1
A value of 0-3 is preferable because dielectric breakdown characteristics and mechanical II properties become good.

Next, it is necessary that 1.21) a BD layer is laminated on at least the surface of the plastic film on which metal vapor deposition is performed.

The thermal characteristics of the 1.2 PBD layer include a melting start temperature of 25 to 9
00℃, preferably 40 to 8
It is 0°C. If the melting start temperature is lower than the above range, blocking between the films will become significant and the film will not be usable. Furthermore, if the melting start temperature is higher than the above range, the adhesion of the deposited metal will be low. Furthermore, the melting end temperature of the 1.2PBD needs to be 100°C or higher, preferably 120°C or higher. If the melting end temperature is lower than the above range J, heat negative (a phenomenon in which the surface polymer melts and whitens) occurs in vapor deposition, and the quality of the vapor deposition surface deteriorates.

In addition, the crystallinity of the polymer is preferably 20 to 20 in order to obtain good adhesion and reduce the occurrence of heat negative drop.
50%, more preferably 30-50%.

Further, the 1.2 bonding ratio (R1,2>) of the polymer is preferably 70% or more, more preferably 90% or more, in order to improve the adhesion of the deposited metal.

In addition, the mel I ~ flow index (MF
I) is preferably 1 to 50Q/10 minutes because it provides good film forming properties.

Further, the crystallinity (χ) of the polymer is 20 to 50%, more preferably 30 to 50%, from the viewpoint of improving dielectric breakdown characteristics and film formability.

Further, when the ash content of the polymer is less than ao p pm and the chlorine concentration is less than 2 oppm, the dielectric breakdown voltage is improved,
This is preferable because ΔC decreases.

The thickness of roughly 1.2 PBDEi is preferably made as thin as possible from the viewpoint of preventing heat loss, and is preferably 5 μm or less. In particular, since the dielectric breakdown voltage of 1.2PBD is lower than that of polypropylene, it is better to make it thinner. From this point of view, the thickness is more preferably 2.5 μm. The lower limit is not particularly limited, but from the viewpoint of uniformity of the 1.2 PBD layer, it is preferably 0.05 μm or more. Further, from the above point of view, it is preferable that the thickness of the layer does not exceed 10% of the thickness of the plastic film serving as the base.

Further, particles may be added to the 1.2PBD layer in order to impart anti-blocking properties. Examples of inorganic particles include silica and titanium oxide. Particle size is 0.0
The thickness is preferably 1 to 1 μm, and the amount added is preferably in the range of 0.01 to 1 wt%. Furthermore, other resins such as polyethylene, polypropylene, etc. may be blended into 1.2PB[)F3, but in order to improve vapor deposition properties, the amount of other resins should be 20 wt% or less, more preferably ' It is preferable to keep it below lQwt%.

Further, the addition of a scouring agent such as a fatty acid amide is also undesirable because it bleeds out to the vapor deposition property and deteriorates the vapor deposition property. It is preferable not to add it as much as possible, or even if it is added, it is preferably added only to the base plus deck film.

The laminated film may be textured on all layers, or only on the surface layer. The degree of unevenness may be changed depending on the purpose, and usually Ra is 0.1 to 100 μm.

Examples of the method for forming the unevenness include embossing, and adding an incompatible resin or inorganic particles to the base plastic film and then stretching the film.

The vertebral body plastic film is made by melt-extruding raw 1'El pellets using an extruder and molding them into a T-die or circular die.
It is formed into a sheet and stretched in one or two axes as necessary.

Examples of the method for forming the 1.2 polybutadiene film on the polyolefin film include the following method.

■ Co-extrusion method: For polymers such as polyethylene that can be extruded at temperatures below 180°C, each polymer is introduced into the same die from multiple extruders, laminated, and extruded. If the extrusion temperature exceeds 180°C, the polybutadiene will decompose or crosslink, which is not preferable.

■ Melt extrusion lamination: Laminate onto the coated base film using a separate extruder.

■Hosotomel 1~Coating: Mel 1~Bath J:
The cap must be coated or coated with 1 or 2 PBD melted [
Laminate onto the base film using 1-L.

■ Solution coating: 1°2 PBD is dissolved in an organic solvent such as toluene or carbon tetrachloride and coated.

In method 1, the 1.2PBD layer and the base film are firmly adhered, and no post-treatment is required to improve the adhesion. However, in methods 2 to 4, the coating film does not have adhesion when simply dripping, and a subsequent heat treatment is required.The treatment temperature is set to be above the melting point of 1.2 PBD and below the melting point of the plastic film. Also,
In this method, method 4 is preferred for forming a polybutadiene layer as thin as possible when the base plastic film is used without orientation (unstretched), or as a uniaxially oriented or biaxially oriented film. In this case, it is preferable to form a polybutadiene layer by methods 1 to 3 before stretching and then perform stretching because the polybutadiene layer becomes thinner. Particularly when forming a film by sequential biaxial stretching with a set of stents, it is easy to form a polybutadiene layer of 1 μm or less by uniaxially stretching the base plastic film, forming a polybutadiene layer by hot melt coating, and then laterally stretching. can.

Methods for depositing metals on such films include ordinary resistance heating, electron beam deposition, sputtering, and ion blasting, but resistance heating and electron beam deposition, which have a particularly low deposition strength, are available. It is effective when doing Furthermore, it is preferable to control the vapor deposition surface temperature to a temperature below the melting end temperature of 1.2 PBD in order to prevent heat loss.

In addition, there are no particular limitations on the vapor-deposited metal, but
In general, anything that can be steamed may be used, such as I, Zn, Ni, Cu, Au, AQ, etc. However, when used for capacitor applications, A1 or Zn,
Alternatively, a multilayer deposited film of A1 and zn, or an alloy deposited film is preferable.

There are various possible forms of the metal vapor deposited film as described above. For example, a 1.2 PBD layer is provided on one side of the base plastic film, and metal vapor deposition is performed only on this layer, and a metal vapor deposition layer is also applied to the opposite side (where 1.2 PBDFi is not provided). Alternatively, a 1.2PBD layer is provided on both sides of a Plus Deck film serving as a base, and metal vapor deposition is performed on both or one side. In short, it requires that at least a 1.2 PBD layer be formed on one side of the base plastic film, and that the layer be metal-deposited.

As mentioned above, such a metal vapor deposited film has good adhesive properties, so when it is used as a dielectric material and an electrode of a capacitor, it exhibits excellent electrical properties such as a small ΔC. be.

Regarding the manufacture of the capacitor, a conventional method for manufacturing a vapor-deposited capacitor can be applied. That is, when using a film that has been steamed on one side, two sheets of this are rolled together. In this case, it is best to use the film according to the present invention as two evaporation films, or one of the films may be a conventionally known evaporation film. When using a film deposited on both sides, a plastic film not deposited with metal is also wound to form a groove on the other dielectric. Such an element is subjected to processes such as heat treatment, heat pressing, etc., spraying of metal onto the ends, attachment of lead wires, immersion in insulating oil, dipping, or casing, as necessary.

In addition, various forms such as a chip-type capacitor in which a large number of vapor-deposited films are stacked and then cut into small pieces can be considered, but the present invention is not limited to such forms in any way.

Terms and measurement methods related to the present invention will be explained below.

(1) Melting start temperature (TS), melting end temperature (Te
): Scanning calorimeter (DSC-H2 manufactured by PerkinElmer)
), and let TS be the temperature at which the endothermic peak associated with melting begins to deviate from the baseline. Further, l at which the melting endothermic peak intersects the baseline again is assumed to be Te.

By the way, the measurement conditions are trial 15mc+, product temperature speed 20℃/
minutes in a nitrogen atmosphere.

<2> 1.2 Bonding Ratio (Rt, 2): Polybutadiene is extracted from the sample film using carbon disulfide.

The extracted polybutadiene 15mc+ was dissolved again in 10mM carbon disulfide, and 10100O0' to 700Cm
Measure the infrared absorption spectrum of -1.

(AλC) is read and calculated according to the following formula based on the Morello method.

C= (1,7455A λC-0,0151A λT
)V=(0,3746A,ly-0,0070
A λC)T=(0,4292A λTO,0129A
λy−0,0454A λC) R1,2(%)=(V/(C+V+T))xloo(3
) Crystallinity (χ.): 1.2PB by density gradient tube method
Measure the density (dS) of sample D at 20°C, and let the crystal density (do) and the amorphous density (d8) be the crystallinity (
χ. ) is obtained by the following formula.

χ = ((d-d)/(do-da”))C
S a Xloo (%) d = 0.889 (q/cm 3) (4) Melt flow index (MFI): ASTM D1238
According to the temperature 150℃ (polybutadiene), 190℃ (
polyethylene), measured at a load of 2160Q, Cl/1
It is expressed in the middle of 0 minutes.

(5) Average surface roughness Ra): JIS 80601-
1976 with a cutoff of 0.25 mm.

(6) Total bending vapor deposition property: The vapor deposition property was evaluated by vapor depositing aluminum on the original film roll by resistance heating vapor deposition to a thickness of about 500.

In addition, a cut sheet of the original film was annealed for 10 minutes at a temperature 10° C. lower than the melting point of the film, and then aluminum was vapor-deposited in a Verge V set steamer to a thickness of about 500 for evaluation.

(7) Apply a cellophane adhesive tape (Diban Co., Ltd.) to the vapor-deposited surface (=1), rapidly peel off the tape, and check the peeling state of the A1 vapor-deposited film as follows. evaluate.

Rank 1: Most of the deposited film peels off.

Rank 2: Approximately 25% of the deposited film remains.

Rank 3: Approximately 50% of the deposited film remains.

Rank 4: About 75% of the deposited film remains.

Rank 5: Most of the deposited film remains.

(8) Surface wetting according to JIS K6768 wetting test method for polyethylene and polypropylene films.

(9) Isotactic + f (II): Cut the sample film into large serrations of about 1 cm square, take a sample of weight = W (mq), put it in a Soxhlet extractor, and boil it at tl.
Extract with tW n-hebutane for 6 hours.

Subsequently, this sample is taken out, thoroughly washed with acetone, dried under vacuum at 60° C. for 6 hours, and weighed.

If the weight is W'(mci>), the degree of isotacticity is determined by the following formula.

II (%) = 100xW-/W (10) Intrinsic viscosity ([η]): AsTM D-160
1 in tetralin at 135°C and is expressed in dD,/Ω.

(11) Planar orientation (ΔN): Using Atsube's refractometer, refractive index in the longitudinal direction of the film (Ny> refractive index in the width direction (N
x) and the refractive index in the thickness direction (Nz>) are measured and calculated using the following formula.

ΔN=(Nx+Ny>/2-'Nz During the measurement, sodium D line is used as the light source, and methyl salidylate is used as the mounting liquid.

(I2) Ash content: JIS-
Measured according to C2330. Note that the butadiene polymer is extracted with toluene.

(13) Chlorine temperature: Measure the butadiene polymer sample according to the randomization analysis method. The J-babutadiene polymer is extracted with toluene.

(kl> Sheet breakdown voltage (BDV): AST
Measured at elevated temperature according to MD149.

(1) Condenser Test 2 The test was conducted under the following conditions.

A: The metal used was aluminum with a surface resistance of 2Ω/mouth. J: The thickness of the evaporation was controlled.

B. Making a capacitor It was prepared by a conventional method so that the capacitance was 5 μF.

Note that polybutene was used as the impregnating oil.

When the thickness of the C0 charging tester base film is 10 μm, the voltage is 450 V (
60Hz), 600V for 14μm (60Hz,
), the test is conducted at an ambient temperature of 70° C., and the rate of change in capacity after 40 days is determined by the following formula.

ΔC(%>=((Ct-02)/CI)X100 where C1: initial capacity (μF) C2: capacity after /IQ days (μF) Tan δ was also measured in the same manner.

2. Examples Next, the present invention will be specifically explained with reference to Examples.

Example 1 Polypropylene (Mitsui Toatsu Chemical Co., Ltd. “Noblen” I)
I = 97%, [η] = 2.25d12/g) was extruded using an extruder, and after solidifying on an extrusion cooling drum at 280 °C,
It was stretched 5 times in the machine direction at 145°C. Next, polybutadiene (Ts=40°C, Te=130°C, MFI
=3C1/10min, R1,2=92%) was coated on the stretched film to a thickness of 10 μm.

The laminated film was then introduced into a stenter at 160° C., stretched 10 times in the transverse direction, heat set while allowing 5% relaxation, and wound up. The composite film obtained in this way has a PP thickness of 15 μm and a polybutadiene thickness of 1 μm.
It was μm.

This film was aluminum-deposited using a resistance heating type evaporator to have a thickness of 500 mm. The metallized film is a first metallized film.
As shown in the table, the uniformity of the deposited film was good, and the adhesion and peeling of cellophane tape before and after heat treatment were good, ranking 5.

Comparative Example 1 A single biaxially oriented polypropylene film formed without 1.2PBDII5 was vapor-deposited in the same manner as in Example 1 without surface treatment such as discharge treatment. The properties of the metallized film thus obtained are shown in Table 1 in comparison with those of Examples.

Since the adhesive force between the vapor-deposited metal and the base film was small, the film easily peeled off due to friction when it was rolled up after vapor deposition, and it failed at rank 1 when peeled with cellophane tape.

Comparative Example 2 The single biaxially oriented film of Comparative Example 1 was subjected to a corona discharge treatment in air, and the surface tension was set to 39 dyn/cm. Although the treated film had been subjected to static elimination treatment, it was found that uneven vapor deposition occurred during vapor deposition, which was thought to be due to electret discharge. In addition, the corona discharge treated film was
After heat treatment at ℃ for 110 minutes, the deposition strength was significantly lowered to rank 2 after peeling off cellophane tape (Table 1).
.

Example 2 In Example 1, a single biaxially oriented polypropylene film formed without a 1.2 PBD layer was coated with a grain size of 0.1
Q, 5wt% of μm titanium oxide added Ts = 30″C
, Te=120℃, MFI=3C1/10/1.2P
This 5 wt % toluene solution was coated using BD to form 1.2 PBI with a thickness of 0.5 μm. The coating film was further annealed in an atmosphere of 150° C. for 5 minutes.

When the film was evaluated for vapor deposition in the same manner as in Example 1, it had good vapor deposition properties and adhesive strength as in Example 1.
There was no change in heat treatment properties (Table 1).

Comparative Example 3 A coating solution was prepared using 1.2PBD (Ts=15°C, Te=95> as in Example 2, and 0.5μ
A polybutadiene layer of m was formed and annealed at 150° C. for 5 minutes. The thus obtained laminated film was wound up into a roll, left to stand for one week at a reduced temperature, and then attempted to be unwound, but a blocking sound was generated during unwinding, and the film broke midway through.

Example 3 Low density polyethylene (MFJ = 4.OQ/10 minutes, density 1
Banquet 0.92 Q/cm3) To real IM example 1 Te for ita 1
．． 2PBD and 2PBD were each introduced into a circular die using an extruder and extruded into a duplex shape to obtain a composite film by inflation film formation. As a result, the thicknesses of low density polyethylene and 1.2 PBD were 14 μm and 2 μm, respectively. The vapor deposition properties of the film were as good as in Example 1, as shown in Table 1.

Example 4 Ethylene propylene random copolymer ([η]=1.
811/q, knee 1): z included fiffi4wt%)
1 and 2 PBD used in the actual flow side 1 were each melt-extruded using an extruder, introduced into the same T-die, and cooled and solidified on a cooling drum subjected to sandblasting. At this time,
1.2 PBD was placed on the non-drum surface side, and the surface was smooth, and the drum surface side was roughened so that Sand Plus 1~ surface was transferred and Ra = 2 μm. At this time, the thickness of the ethylene propylene random copolymer and 1.2 PBD was 40 μrT'l and 15 μm. When the film was evaluated by vapor deposition, clouding occurred due to the thickness of the 1.2 PBD layer, but the adhesion of the silent film did not change upon annealing and was ranked 5, which was poor and good.

Example 5 According to Example 1, a composite two-layer oriented film was obtained.

However, the thickness of the 1.2 PBD layer was 1 μm, the thickness of the polypropylene film was 14 μm, and the orientation was 15×10 −3 .

The sheet-like BDV of the film was 310 V/μm, which was good. [Next,] A capacitor was prepared by the above-mentioned method in order to briefly evaluate its characteristics as a densifier. As a result, t
An δ and ΔC were 0°01% and 0.1%, respectively, which were excellent characteristics.

Comparative Example 4 Using the film of Comparative Example 2, the characteristics as a capacitor were measured in the same manner as in Example 5. As a result, tanδ is 0
．． 03%, ΔC is 1.0%, which is extremely bad. Here, the reason why tan δ deteriorates is that the actual T1 resistance of the electric currents 4 to 4 increases due to the disappearance of water.

Example 6 1 Poly V[ with I=98%, [η]=1.85dα/q
] A biaxially oriented film with a plane orientation of 16×10 −3 and a thickness of 10 μm was obtained from pyrene pellets using a sequential biaxial stretching device with a stenter set.

Here, Ts=40°C, Te=135°C1R1,2=
A butadiene polymer of 94%, MFI=3C 1/10 min was dissolved in 1 to 1 to 1 toluene to create a 6 wt % solution.

This solution was applied to one side of the previously formed biaxially oriented PP film using a coating device, the solvent was dried in an atmosphere of 120°C, annealed at 140°C in an air atmosphere,
PP thickness 10μm, butadiene polymer thickness 0.5μm
A composite film was obtained.

The sheet-like BDV of the film was 320 V/μm, which was good, and as shown in Table 1, the film had a good capacitor density of 1 to 1.

Comparative Example 5 The 2[111-way oriented PP film coated in Example 6 was subjected to corona discharge treatment, and silicon metal (S i ) was vapor-deposited by spuck-evaporation method to form a vapor-deposited film of 100 people.
Subsequently, 1 was vapor-deposited to create a layer.

The results were extremely poor as shown in Table 1.

As described above, the product of the present invention was found to be a highly stable densifier with little change over time.

Effect of Ho0 invention The effects of the present invention are listed below.

The metal-deposited film according to the present invention has the following characteristics: (1) strong adhesion of the metal to the vertebral body film;

■ Since no corona discharge treatment is applied, there is no suction of dust, and there is no uneven deposition due to discharge phenomena.

■ There is little change over time in the adhesion between the base film and the total evaporation flexure, resulting in a consistently uniform evaporation film.

The metal capacitor according to the present invention has the following features: (1) Changes in capacitance over time when AC voltage is applied are extremely small, and changes in dielectric loss over time are also small.

■ It is extremely advantageous in terms of cost.

Claims (2)

[Claims] (1) A 1 and 2 polybutadiene layer having a melting start temperature of 25 to 90°C and a melting end temperature of 100°C or higher is provided on at least one side of the plastic film, and a metal vapor deposition layer is provided on the surface of the 1 and 2 polybutadiene layer. A metal-deposited film characterized by the following: (2) At least one side of the plastic film is provided with 1 and 2 polybutadiene layers having a melting start temperature of 25 to 900°C and a melting end temperature of 100°C or higher, and
A capacitor characterized by using a metallized film in which a metallized layer is provided on the surface of a polybutadiene layer.