CN102723196B - Including melt drawn film as dielectric membrane capacitance - Google Patents

Abstract

The present invention relates to include that melt drawn film is as dielectric membrane capacitance, it includes (1) conductive electrode and (2) semi-crystalline polymer dielectric film, the thickness of described semi-crystalline polymer dielectric film is 1 micron 80 microns, described semi-crystalline polymer dielectric film via melt drawn extrusion method, by die head (ring die head or flat-mould head), under the die head temperature higher than described semi-crystalline polymer fusing point, use the 30 or higher draw-down ratios ratio of thickness (die gap with) to manufacture.The lowest shrinkage factor is at high temperature demonstrated until it melts by the semi-crystalline polymer dielectric film of such melt drawn extrusion method manufacture.Can use at a much higher temperature compared with including the conventional two-axis alignment films electrolyte manufactured by same plastic material including the dielectric capacitor of such low shrinkage film.

Description

Including melt drawn film as dielectric membrane capacitance

Background technology

Membrane capacitance has two big classes: metal forming-membrane structure and metallized film structure.Paper tinsel-membrane capacitance is by moulding Material film and the alternating layer manufacture of the metal forming as electrode, and metallization film capacitor has direct vacuum The metal being deposited on film is as electrode.

For membrane capacitance, film electrolyte can be by polyphenylene sulfide (PPS), polystyrene (PS), poly-carbonic acid Ester (PC), poly-(ethylene glycol terephthalate) (PET), poly-((ethylene naphthalate)) (PEN), poly- Vinylidene fluoride (PVDF), high density polyethylene (HDPE) (HDPE) or polypropylene (PP) manufacture.

For the conventional dielectric example of BOPP film.In the temperature less than PP fusing point after cooling down from extrusion The conventional BOPP film of the lower biaxial orientation of degree has been widely used as in many different types of membrane capacitances Electrolyte.The cost of PP material is relatively low.Its film electrolyte turns to electrode by metal and carries The low fissipation factor (dissipation factor) varied with temperature for (1), (2) high breakdown strength and (3) Excellent self-healing performance.But, although the dielectric fusing point of BOPP film is up to 163 DEG C, but it is hot Dimensional stability is limited, the most up to 105 DEG C.It is almost low 55-60 DEG C than fusing point.Low Thermal dimensional stability is owing to its low orientation temperature causes.In the thermal dimensional stability level that this is low In the case of, it is not suitable for the capacitor such as pulse power electricity in self-heating or heated environment Container, automobile capacitor and the application of surface mount capacitor.Used as surface mount capacitor, Then comprise the heat that the conventional dielectric capacitor of BOPP film cannot stand to be conducted during installing by welding. For such application, typical case's mulch film electrolyte needs its thermal dimensional stability at least up to 125 DEG C. If it is necessarily used in self-heating or heated environment due to the performance of above-mentioned excellence, comprise routine The membrane capacitance of BOPP film needs to be used in combination with cooling system, and this adds cost and sky undesirably Between.

Generally, as dielectric biaxial orientation (biaxially oriented) film in membrane capacitance is applied Thermal dimensional stability is frequently not and consumes very much.The PET film electricity that another common example is biaxially oriented Medium.Let it be to the greatest extent, and fusing point is up to 250 DEG C or higher, but its dimensional stability is only up to about 125℃.It is lower 125 DEG C than fusing point.

These Biaxially oriented films are generally stretching less than at a temperature of material melting point.After the stretch, When being again heated to film close to draft temperature, this film often shrinks back.

Have attempted to improve and comprise the conventional dielectric capacitor of BOPP film heat at a higher temperature surely Qualitative.

United States Patent (USP) 6127042 proposes the capacitor 1 comprising following high-modulus PP film: its relative to Prior art have in longitudinal direction (machine direction) at 120 DEG C about 1.9% and at 140 DEG C about The percent thermal shrinkage percentage ratio of the improvement of 2.5%.This shrinkage factor is the highest for high temperature application.

United States Patent (USP) 6687115 proposes and comprises as dielectric conventional PP film and two metal electrodes Capacitor 2.For the heat stability improved, this capacitor must the most very slowly It is heated to the highest temperature range (from 120 DEG C to 200 DEG C) then cool down.After such process, This capacitor can have the heat stability higher than conventional capacitor.But, this technology does not has conventional skill Art is practical.First, electrode needs metal electrode, thus eliminate in metallization film capacitor can Can application.Secondly, it is believed that the technique manufacturing such capacitor is the most time-consuming.Even if consume is extra Time is acceptable, by extra processing step (vacuum, heat and cool down), the system of this capacitor Make and will pay higher cost.

In the present invention, membrane capacitance uses melt drawn half hitch epitaxial electrolyte to manufacture, described melt Stretching half hitch epitaxial electrolyte compared with the conventional Biaxially oriented film electrolyte manufactured by same materials There is under higher temperature much higher dimensional stability.

Summary of the invention

In the present invention, membrane capacitance melt drawn half hitch epitaxial electrolyte manufactures, and described melt draws Stretch the half hitch epitaxial electrolyte temperature at the most immediately lower than fusing point of (right below) this half hitch epitaxial Under, there is the dimensional stability (less than 1% shrinkage factor in MD and in TD) of greatly improvement.Should Membrane capacitance can be paper tinsel-membrane structure or metallized film structure.Comprise the dimensionally stable of such improvement The dielectric membrane capacitance of film with comprise the conventional two-axis alignment films manufactured by same materials dielectric that A little capacitors are compared, and can use at a much higher temperature.

Accompanying drawing explanation

Fig. 1 is to make dielectric film A and BOPP free shrink 30 minutes in convection oven.

Fig. 2 is HTLS PP (dielectric film A) and BOPP 30 minutes freely receive at the specified temperature The contrast of shrinkage.

Fig. 3 is the temperature dependency of the capacitor with HTLS PP film (dielectric film B).

Fig. 4 is that the temperature dependency of the capacitor with HTLS PP film (dielectric film B) is (reheated Capacitor).

Detailed description of the invention

The uniqueness of the membrane capacitance in the present invention is that the film electricity that height dimension is stable at relatively high temperatures is situated between Matter.In the present invention, this film electrolyte is passed through unique melt drawn method system by semi-crystalline polymer Make.Such membrane capacitance can be made into two types for different application: metal forming membranous type and metal Change membranous type.

Melt drawn method:

In the present invention, described melt drawn method is such method: the most unidirectional traction is melted Melt semi-crystalline polymer, then make this through traction by the such as empty gas and water of hardening media or quenching roller Molten polymer quenches via crystalline film.This melt drawn method can pass through melt extrusion drawing process It is easily achieved.One of example of melt extrusion drawing process comprises the following steps.Melted hypocrystalline Polymer can first pass through extruder and plasticate, and is then extruded by narrow die gap.Then, With speed drawing this molten polymer more faster than the molten polymer speed at die head exit, and And quench immediately in position hardening media apart from described die head exit about 0.05-3 inch in the vertical Fire, with via crystalline film forming.Described die head can be flat-mould head or ring die head.Described hardening media Can be quenching roller, water or air.The semi-crystalline polymer film through melt drawn obtained is the most just Dimensional stability (pole is demonstrated well at a temperature of melt temperature less than the crystal in this semi-crystalline polymer Low shrinkage factor, less than 1%).Generally, for the ease of manufacturing and performance evenly, preferably ring die head With quenching cold air.

In the melt extrusion drawing process using flat-mould head, can be from flat-mould head with ratio at die head exit The faster speed of molten polymer draw this molten polymer in the vertical.In lead away from Away from die head exit about 0.05-3 inch, will be located in an air knife or the position of this fused film logistics side Two air knives (depending on required temper grade) in each side of this smelt flow are applied to this through traction Smelt flow on.After quenching and partially crystallizable, the film obtained demonstrates amazing at height Dimensional stability under Wen.

Distraction procedure in using the melt extrusion drawing process of ring die head or flat-mould head is by such as Lower realization: use driven voller or one group of driven nip rolls (nip roll) with than melting at die head exit Melt the film that the faster speed drawing of polymer is cooled.

In the melt extrusion drawing process using ring die head, this molten polymer is extruded, in distance Quenched by air ring at die head exit about 0.05-3 inch, and draw at faster speed with shape Become film bubble.Then make this film bubble collapse to form double-deck film roll by one group of nip rolls.With flat-mould head class Seemingly, the melt drawn of ring die head is used vertically upward, vertically downward or flatly to arrange.This is to adopt Unique blown film process with low blow-up ratio (blow-up ratio).Blow-up ratio is defined as vesicle diameter and ring Pressure head diameter ratio.In the present invention, it is preferred to blow-up ratio is 3 or less.Use lower blow-up ratio, The film that easier realization height dimension at relatively high temperatures is stable.But, for relatively high dielectric strength, In order to realize more preferable intensity homogeneity, it is suitable to need for orientation the most to a certain degree Blow-up ratio.Similar with flat-mould head, in extrusion, quench and with than the melt polymerization at die head exit After the speed drawing that the extruded velocity of thing is fast, use the melt extrusion drawing process of ring die head to produce and exist The film of amazing dimensionally stable under high temperature.

During melt drawn, draw-down ratio (drawdown ratio) is defined as die gap and obtained film The ratio of thickness.Using higher draw-down ratio, it is more stable that this melt drawn method produces at high temperature size Film.The most minimum draw-down ratio is 30.The upper limit of described draw-down ratio may be up to 250-300.But, Using the highest draw-down ratio, this melt drawn method will produce the most uneven film.Therefore, There is the Optimal Ratio depending on material parameter such as degree of crystallinity and molecular weight.During affecting melt drawn Another key factor of orientation be the hardening media distance from die head exit.The shortest distance is to melted Polymer applies the highest strain, thus the orientation of telolemma is the highest.The fastest draw speed is to through leading The molten polymer drawn applies the highest strain rate, thus produces the highest orientation journey in telolemma Degree, this will improve the dielectric strength of film.The degree of crystallinity of film can improved less than annealing at a temperature of fusing point. Generally, the more high-crystallinity of film makes dielectric strength improve.

In a word, in the melt drawn method of the present invention, just cold by hardening media such as cold air But molten polymer is to be formed before telolemma, makes described molten polymer be orientated.Make with molten condition Molecularly oriented, then makes described molecule freeze film forming.Final oriented film exist little residual Residue stress or there is not residual stress, and for described film, at a temperature of less than this film fusing point Do not observe contraction.The alignment films of the present invention can take in the case of using flat-mould head the most in the vertical To, and can be on vertical and horizontal two direction when blow-up ratio is more than 1 in the case of ring die head using Orientation.This is with for conventional BOPP, conventional BOPET and other Biaxially oriented film, (it is successively via such as Manufacture down: first for the forming process by quenching, be then reheating process, and be finally double Axle orientation process) conventional two-axis method for alignment very different.

Semi-crystalline polymer:

Conventional or business semi-crystalline polymer refers to have the crystalline polymer less than 100% degree of crystallinity.? In the present invention, the scope of semi-crystalline polymer include that (1) conventional business semi-crystalline polymer or they Copolymer, (2) such semi-crystalline polymer and other polymer or the blend with other additive, (3) such routine or business semi-crystalline polymer or the monolayer of their copolymer, (4) such routine Or the multilamellar of business semi-crystalline polymer, and (5) comprise routine or the film of business semi-crystalline polymer. Then can quench by the semi-crystalline polymer in the present invention from die head exit melt extrusion, stretching, and And form film via partially crystallizable, by described partially crystallizable, formed and the coarse-grain of fixed orientation (macro-crystal) structure.

Molten polymer:

In the present invention, molten polymer be defined as wherein crystal by by conduction or obtained by friction The melted heated semi-crystalline polymer of heat.Generally, crystal melt occurs higher than fusing point Temperature.More practically, described molten polymer is by squeezing higher than at a temperature of crystalline melting point 20-60 DEG C Go out the acquisition of plasticating of machine.The precise conditions of the suitable molten polymer in the present invention depends on half The character of crystalline polymer and selected drawing process.Example section below describes Some examples for the condition of molten polymer.

The dielectric feature of film obtained in the present invention and performance

The film obtained by the melt drawn method described in the present invention demonstrates that (1) is in the upper pole of longitudinal direction (MD) High intensity, simultaneously in laterally (TD) upper relatively low intensity, and the size that (2) are the highest Stability (low-shrinkage on MD or on TD).Each between MD and TD of film-strength Anisotropy mainly causes due to melt drawn on MD.For higher dielectric strength, can lead to Cross the blow-up ratio more than 1 to be controlled into and have to a certain degree in the horizontal by the film using ring die head manufacture Orientation.

Method of testing:

MI: melt index (MI) ASTM D 1238；PE:190 DEG C/2.16Kg

MFI: melt flow index .ASTM D1238；PP:230 DEG C/2.16Kg

Fusing point: test material sheet (about 20mg) is placed in aluminum dish, with 10 DEG C/min from room temperature The rate of heat addition carries out differential scanning calorimetry (DSC).It is recorded as testing the molten of material by maximum endothermic peak Point.

Shrinkage test: by membrane sample with 3 inches of circle marks, be maintained at Manila file (manila Folder) in, be placed in expectation test temperature convection oven in 30 minutes.After 30 minutes, will This film takes out from baking oven and cools down to measure shrinkage factor level.This shrinkage factor can pass through lost area Determine with the ratio of initial area or by the lineal measure of loss with the ratio of initial length.

The embodiment of dielectric film A

To there is the MFI of 2.0g/10 minute and the acrylic resin of about 165 DEG C of fusing points is being equipped with Extrude on 2 inch diameter extruder of 400mm ring die head.The temperature of extruder and die head is set to 220 ℃.Air ring is arranged on ring die head top higher than die face about 0.75 inch, and molten material flows stretching By this air ring, it is pulled up to higher than described air ring about with the draw line speed of 26 ms/min 12 feet batch (take-up) nip rolls equipment.Draw-down ratio is 115, and the blow-up ratio of film bubble is about 1.The rotating speed of regulation extruder screw to have 12 micron membranes, and regulate the pressure of quenching air with There is smooth film.By batching nip rolls equipment following set of collapse frame (collapsing described Frame) it is two membranes by the film bubble collapse of this drawn.Then, will pass through described in batch nip rolls equipment After this two membranes be wound into film roll.

The embodiment of dielectric film B

To there is the MFI of 2.0g/10 minute and the acrylic resin of about 165 DEG C of fusing points is being equipped with Extrude on 1.5 inch diameter extruder of 400mm ring die head.The temperature of extruder and die head is set to 225℃.Air ring is arranged on ring die head top higher than die face about 0.75 inch, and molten material flows draws Extend through this air ring, be pulled up to higher than described air ring about with the draw line speed of 22 ms/min 12 feet batch nip rolls equipment.Draw-down ratio is 200, and the blow-up ratio of film bubble is about 1.Regulation The rotating speed of extruder screw is to have 6 micron membranes, and the pressure regulating quenching air is smooth to have Film.By at the described nip rolls equipment following set of collapse frame that batches by flat for the film bubble of this drawn Bubble is two membranes.Then, will pass through described in batch nip rolls equipment after this two membranes be wound into film roll. The embodiment of dielectric film C

The acrylic resin of the MFI and about 165 DEG C of fusing points with 2.0g/10min is being equipped with Extrude on 1.5 inch diameter extruder of 400mm ring die head.The temperature of extruder and die head is set to 225℃.Air ring is arranged on ring die head top higher than die face about 0.75 inch, and molten material flows draws Extend through this air ring, be pulled up to higher than described air ring about with the draw line speed of 22 ms/min 12 feet batch nip rolls equipment.Draw-down ratio is 200, and the blow-up ratio of film bubble is about 1.Regulation The rotating speed of extruder screw is to have 4 micron membranes, and the pressure regulating quenching air is smooth to have Film.By at the described nip rolls equipment following set of collapse frame that batches by flat for the film bubble of this drawn Bubble is two membranes.Then, will pass through described in batch nip rolls equipment after this two membranes be wound into film roll.

The embodiment of dielectric film D

To there is the MI of 0.35g/10min and the high-density polyethylene resin of about 132 DEG C of fusing points at dress It is furnished with on 2 inch diameter extruder of 400mm ring die head extrusion.The temperature of extruder and die head is arranged It it is 195 DEG C.Air ring is arranged on ring die head top higher than die face about 1 inch, and molten material flows draws Extend through this air ring, be pulled up to higher than described air ring about with the draw line speed of 26 ms/min 12 feet batch nip rolls equipment.Draw-down ratio is 156, and the blow-up ratio of film bubble is about 1.Regulation The rotating speed of extruder screw is to have 8 micron membranes, and the pressure regulating quenching air is smooth to have Film.By at the described nip rolls equipment following set of collapse frame that batches by flat for the film bubble of this drawn Bubble is two membranes.Then, will pass through described in batch nip rolls equipment after this two membranes be wound into film roll.

The embodiment of dielectric film E

To there is the MI of 0.35g/10min and the high-density polyethylene resin of about 132 DEG C of fusing points at dress It is furnished with on 1.5 inch diameter extruder of 400mm ring die head extrusion.The temperature of extruder and die head sets It is set to 205 DEG C.Air ring is arranged on ring die head top higher than die face about 1 inch, and molten material flows Draw province by this air ring, be pulled up to higher than described air ring with the draw line speed of 26 ms/min About 12 feet batch nip rolls equipment.Draw-down ratio is 250, and the blow-up ratio of film bubble is about 1. The rotating speed of regulation extruder screw is to have 5 micron membranes, and regulates the pressure of quenching air to have Smooth film.By at the described nip rolls equipment following set of collapse framework that batches by this drawn Film bubble collapse is two membranes.Then, will pass through described in batch the winding of this two membranes after nip rolls equipment Become film roll.

High temperature low-shrinkage (HTLS) film

The most noticeable feature of melt drawn film is its temperature at the most immediately lower than melting point resin Under low-down shrinkage factor.As a example by dielectric film A.Dielectric film A is by having 165 DEG C melted The PP resin manufacture at peak.The PP resin used at this is semi-crystalline polymer.In semi-crystalline polymer Crystal generally start to melt at former DEG C of described peak, then by described peak, then at described peak The most several DEG C the most melted.Therefore, at peak temperature, the crystal in semi-crystalline polymer is the most molten Melt.

In free shrink is tested, dielectric film A, with the circle mark of 3 inches, is maintained at Manila literary composition In part folder, it is placed in the convection oven of 165 DEG C 30 minutes.After 30 minutes, by this film from baking Case takes out measure contraction level.As shown in fig. 1, do not observe contraction at all.Contrast with this, Business BOPP film is placed in together with dielectric film A in the test of this free shrink.The just area in circle For, this business BOPP film is contracted to the 30% of initial circle, net loss 70%.Freely received by this Contracting test, is tested dielectric film A, as shown in Figure 2 the most at other temperatures.With often Rule BOPP dielectric film and the conventional BOPP dielectric film of other prior art, dielectric film A Demonstrate considerably higher dimensional stability.

Using identical PP resin, dielectric film B with C is also identical with dielectric film A performance.Separately Outward, using the HDPE resin with 132 DEG C of fusing points, dielectric film D with E freely receives identical Contracting test does not demonstrates contraction at 128 DEG C at all.

There is the embodiment of the HTLS dielectric membrane capacitance of PP film

Comprise the HTLS dielectric capacitor of PP film can be paper tinsel-membrane structure or be metallized film structure. They can construct with different size according to the demand of different application.Electricity is manufactured from HTLS PP film electrolyte The method of container is similar with the method being manufactured capacitor by conventional BOPP film electrolyte, although processing skill Art can be slightly different.

A. paper tinsel-membrane structure

It is coiled into the combine volume of paper tinsel/bilayer HTLS PP/ paper tinsel/bilayer HTLS PP to have at two ends and stretches out The capacitor of foil electrode.The HTLS PP film used is 6 microns of thick dielectric film B.At paper tinsel electricity The dielectric gross thickness of film between pole is 12 microns.Paper tinsel as electrode is aluminium foil.

Fig. 3 shows the temperature dependency of the electric capacity of such paper tinsel/membrane capacitance.Substantially, from room temperature to Close to the temperature of fusing point, electric capacity keeps fairly constant.At temperature scanning the most for the first time In, electric capacity is slightly increased rather than declines.Think that double-deck HTLS PP film softens and more closely exists Together.After being cooled to 25 DEG C, due to the thickness contraction of film, electric capacity increases further, such as Fig. 4 Shown in.When capacitor is heated to 165 DEG C, electric capacity is decreased to scan at 165 DEG C for the first time Level.It is initially observed the reduction of electric capacity in reruning, is about 5-7% from room temperature to 165 DEG C, This is presumably because what thickness swelling caused.Circulate in through twice temperature scanning and this capacitor is launched Afterwards, the contraction in machine and transverse direction of this film is not observed.

In the dielectric test with mutually isostructural capacitor (2.2mF), as shown in Figure 3, this The dielectric strength of the capacitor of sample is up to 1000 volts of DC at 140 DEG C, and this is and the most substantially phase Same performance.

B. metallized film structure

One of key challenge of metallization film capacitor is that capacitor carries out end metal injection (metal End spray) to be electrically connected to terminal.For metallization BOPP film capacitor, need to be advantageously controlled End course of injection, to guarantee not cause metalized film heat damage.Depend on supplier, be higher than 105 DEG C, conventional BOPP film starts to shrink to different degree.According to SB Electronics³Description, When a failure occurs, the electrode-ejecta interface along adjoining edge becomes large area disconnection.At another In part report, Zhonghua Kong etc.⁴Report metallization PP (conventional) membrane capacitance at capacitor (blow out) will be burst from the centre position of capacitor when surface temperature is higher than 110 DEG C.

Having high temperature dimensional stability, HTLS PP film as implied above has more than conventional BOPP film The leeway of 60 DEG C is sprayed for end.Metal jet thing can be deeper between film.Expection end Ejecta is firmer with the connection of metallization HTLS PP membrane capacitance.HTLS PP film is from high temperature Lower size is more stable.The two benefit increases a large amount of value for metallization HTLS PP membrane capacitance together.

Volume one is had the HTLS PP film (dielectric film A) of 12 micron thickness and 20 inches wide at this film Centre one identical film (1 inch wide) is covered, and then the side sided corona treatment at this band arrives 42dyne/cm level, then in metallizer (metalizer) with aluminum metallization be 3.3(0.9ohm/in²) optical density.Then, remove obscured film, obtain such metalized film: In the centre of this metalized film, there is the most metallized band.Then, by this metalized film rip cutting (slit) two 3 inches of wide metallized ribbon are become: one has 1/4 inch on right side and do not metallizes clearly Edge；Another has 1/4 inch of metallization edge the most non-in left side.Then by the two metal Change tape wrapping is on 1.5 inches of refills, for metallization film capacitor.Then this metallization film capacitor Zinc sealing both ends is sprayed, to be electrically connected to two electrodes the most equably by end.Pass through The hand-held digital multimeter of RadioShack is measured, and this metallization film capacitor electric capacity at room temperature is 21 Microfarad.Then this metallization film capacitor is placed in the convection oven of 140 DEG C 1 hour and by it Take out for capacitance measurement.Reading when just taking out from baking oven is that 20.1 microfarads are then when under cooling About 21 microfarads are reversibly returned to when coming.Do not observe that electric capacity deteriorates.Heat 1 hour at 140 DEG C After, do not observe explosion, and do not observe any disconnection at electrode-injection interface.

Claims (15)

1. capacitor semi-crystalline polymer dielectric film, its thickness is 1 micron-80 microns, and it is by selecting Semi-crystalline polymer manufacture from following: high density polyethylene (HDPE), polypropylene, polybutene, polypenthylene, PET, PEN, nylon, their copolymer or their melt blended material, it is at least one of which form, institute State in the way of the direction of the film molecular axis to have is roughly parallel to film surface and be orientated, when being heated to temperature When being up to about the fusing point of described semi-crystalline polymer, oriented film shows the percent thermal shrinkage less than 1%, Wherein said film is the film of simple tension the most in the vertical, and wherein said percent thermal shrinkage refers to It it is the shrinkage area ratio with initial area of loss.

Capacitor semi-crystalline polymer dielectric film the most according to claim 1, it is by polypropylene system Making, it has the shrinkage factor less than 1% at 130 DEG C in the vertical and in the horizontal.

Capacitor semi-crystalline polymer dielectric film the most according to claim 2, it is by polypropylene system Making, it has the shrinkage factor less than 1% at 140 DEG C in the vertical and in the horizontal.

Capacitor semi-crystalline polymer dielectric film the most according to claim 3, it is by polypropylene system Making, it has the shrinkage factor less than 1% at 150 DEG C in the vertical and in the horizontal.

Capacitor semi-crystalline polymer dielectric film the most according to claim 4, it is by polypropylene system Making, it has the shrinkage factor less than 1% at 155 DEG C in the vertical and in the horizontal.

Capacitor semi-crystalline polymer dielectric film the most according to claim 5, it is by polypropylene system Making, it has the shrinkage factor less than 1.5% at 160 DEG C in the vertical and in the horizontal.

7. membrane capacitance, including (1) conductive electrode and (2) capacitor according to claim 1 hypocrystalline Polymeric dielectric film, described film is at least one of which form.

Membrane capacitance the most according to claim 7, the semi-crystalline polymer wherein manufacturing dielectric film is Polypropylene.

Membrane capacitance the most according to claim 8, it has at 130 DEG C in the vertical and in the horizontal There is the polypropylene dielectric film of the shrinkage factor less than 1%.

Membrane capacitance the most according to claim 9, it has at 140 DEG C in the vertical and laterally On there is the polypropylene dielectric film of the shrinkage factor less than 1%.

11. membrane capacitances according to claim 10, it has at 150 DEG C in the vertical and laterally On there is the polypropylene dielectric film of the shrinkage factor less than 1%.

12. membrane capacitances according to claim 11, it has at 155 DEG C in the vertical and laterally On there is the polypropylene dielectric film of the shrinkage factor less than 1%.

13. membrane capacitances according to claim 12, it has longitudinally and laterally goes up at 160 DEG C There is the polypropylene dielectric film of the shrinkage factor less than 1%.

14. methods manufacturing capacitor semi-crystalline polymer dielectric film according to claim 1, bag Include

(1) by a die head, it is selected from such as lower die head: flat-mould head and ring die head,

(2) die gap of die head selected by is more than 30 with the ratio of film thickness,

(3) adding hot-extrudable melted semi-crystalline polymer, it is selected from one of following semi-crystalline polymer: high Density polyethylene, polypropylene, polybutene, polypenthylene, PET, PEN, nylon, their copolymer, With their melt blended material,

(4) the most unidirectional traction melts semi-crystalline polymer,

(5) the melted semi-crystalline polymer extruded with a fluid away from die head from 0.05 inch to 3.0 English The surface one side at least within of the very little institute of cooling rapidly extruded film, this fluid is selected from as follows: air and water.

15. manufacture methods according to claim 14, the wherein die gap of selected die head and film thickness Ratio be 250-300.