KR20010102451A - Biaxially oriented film for the production of ceramic capacitors - Google Patents

Abstract

The present invention relates to a method of using a multilayer film as a support film in the manufacture of a ceramic capacitor, wherein the multilayer film has a base layer and at least one top layer A, the top layer A comprising a propylene polymer and at least one incompatible polyolefin. Incompatible polyolefins are LDPE, HDPE, MDPE, ethylene-propylene copolymers or cycloolefins or syndiotactic polymers, the surface of top layer A having a greater roughness than the opposite surface of the film, A smoother surface is provided with a ceramic coating, which is dried and then separated from the support film.

Description

Biaxially oriented film for manufacturing ceramic capacitors {BIAXIALLY ORIENTED FILM FOR THE PRODUCTION OF CERAMIC CAPACITORS}

Ceramic capacitors are capacitors whose dielectric consists of ceramic layers. To produce this capacitor, first the ceramic starting material, which is usually a ceramic powder, is transformed into a highly viscous composition using a suitable solvent and binder. In a subsequent process step, the composition is also transformed into a thin layer, which is then provided with a metal layer (capacitor electrode). This ceramic layer covered in this way is formatted, stacked up, pressed, and finally fired at elevated temperature to sinter the ceramic. Useful capacitors are then produced from this blank by providing electrodes with electrical contacts and encapsulated with a synthetic resin coating (Spektrum der Wissenschaft, September 1988, p. 88).

The ceramic layer may be made of different materials. Suitable ceramic materials are known in the art, for example, metal oxides and / or titanates such as barium titanate, magnesium silicate, titanium dioxide, bismuth oxide and mixtures thereof. This ceramic is distinguished by a high dielectric constant.

Thereafter, various processes are known for producing a ceramic layer that becomes a capacitor. For example, first, a highly viscous ceramic coating composition is applied to a suitable flexible substrate and dried. The substrate must be removed again in a later process step, during which the resulting ceramic layer or film must not be damaged when the substrate is removed. For this purpose, in the prior art, it is known to use paper, a polyester film or a polypropylene film.

JP 06305041 A describes an oriented multilayer film having a polypropylene base layer with a surface roughness Ra of 0.08 μm to 0.5 μm and a top layer of ethylene-propylene copolymer. The roughness values of the two surfaces should not differ by more than 0.1 μm. The ceramic layer produced on this film can only be dried at low temperatures because otherwise the adhesion of the ceramic layer to the film becomes so great that a defect occurs in the ceramic film when peeling off the support film.

JP 01196111 A describes a single layer oriented film comprising polydimethylsiloxane as a release agent for the ceramic layer. However, polydimethylsiloxane can be partially transferred to the surface of the ceramic layer, which impairs the adhesion of the metal coating to this surface.

JP 60206620 H describes a film made from a mixture comprising polypropylene, polymethylpentene and HDPE. Due to HDPE this film is said to have good release properties and surface roughness.

The present invention relates to biaxially oriented multilayer polyolefin films used as support films for ceramic layers. In addition, the present invention relates to a method of manufacturing a ceramic capacitor.

It is an object of the present invention to provide a film suitable as a support film for the ceramic layer. On the other hand, there must be adequate adhesion between the film and the ceramic layer in order for the ceramic material to be applied well and the coated film to be wound well. At the same time, it should be possible to remove the ceramic layer from the film after drying without damaging the ceramic layer, in particular its surface. Considering the ceramic layer, it is required that the ceramic layer should have as smooth a surface as possible after peeling off the film.

This object can be achieved in accordance with the present invention using polyolefin multiple films oriented as a support film when manufacturing ceramic capacitors, where

The multilayer film consists of a base layer and at least one top layer A, wherein the top layer A comprises a propylene polymer and at least one incompatible polyolefin, wherein the incompatible polyolefin is LDPE, HDPE, MDPE, ethylene- Propylene copolymer or [lacuna],

The surface of the top layer A has a rougher surface than that of other films,

The film is provided with a ceramic coating on the smoother surface of the film which is dried and then separated from the supporting film.

The base layer of the multilayer film according to the invention consists essentially of polyolefins, preferably propylene polymers and additives which are optionally added in each case in an effective amount. The base layer generally comprises at least 90% by weight, preferably from 95% to less than 100% by weight of polyolefin.

Polypropylene polymers comprise predominantly (at least 90%) propylene and have a melting point of at least 140 ° C and preferably from 150 ° C to 170 ° C. Isotropic polypropylene having a content of 6 wt% or less in n-heptane, a copolymer of ethylene and propylene having a ethylene content of 5 wt% or less, and a C ₄ -C ₈ -α having an α-olefin content of 5 wt% or less Copolymers of -olefins and propylene represent preferred propylene polymers for the base layer, particularly preferred propylene polymers are co-array polypropylenes. The melt flow index of the propylene polymer relative to the base layer is generally from 0.5 g / 10 min to 15 g / 10 min, preferably from 3 g / 10 min to 8 g / 10 min at a load of 21.6 N (DIN 53 735) at 230 ° C. to be. The weight percentages indicated are based on each copolymer.

The top layer A disposed on the surface of the base layer comprises a propylene polymer and at least one incompatible polyolefin. Incompatible polyolefins are generally present in the top layer in amounts of 0.5% to 30% by weight, preferably 1% to 25% by weight, more preferably 3% to 15% by weight. The propylene polymer is present in an amount from 70% to 99.5% by weight, preferably from 75% to 99% by weight, more preferably from 85% to 97% by weight. If desired, the top layer may additionally include additives in an effective amount in each case.

The propylene polymer of the uppermost layer A comprises mainly (at least 90%) propylene and has a melting point of at least 120 ° C, preferably from 140 ° C to 170 ° C. co-array polypropylene having a content of 6 wt% or less in n-heptane, a copolymer of ethylene and propylene having a ethylene content of 10 wt% or less, and a C ₄ -C ₈ -α-olefin having an α-olefin content of 5 wt% or less; Copolymers of propylene represent preferred propylene polymers for the base layer, particularly preferred propylene polymers are homo-arranged polypropylene homopolymers. The melt flow index (MFI) of the propylene polymer relative to the top layer is generally 0.5 g / 10 min to 15 g / 10 min, preferably 3 g / 10 min to 10 g / 10 min at a load of 230 ° C. and 21.6 N (DIN 53 735). The weight percentages indicated are based on each copolymer. The MFI of the top layer polymer is at least equal to, or generally larger than, the MFI of the base layer (about 25% to about 100%).

Incompatible polyolefins are those which form a separate phase without being completely mixed with the polypropylene of the top layer A. This incompatibility results in a constant roughness for the surface desirable in the present invention. Suitable incompatible polyolefins are HDPE, MDPE, LDPE or syndiotactic polypropylene or cycloolefin polymers.

For the present invention, the melt flow index MFI measured at 21.6 N / 190 ° C. according to ISO 1133 is 0.1 g / 10 min to 2.0 g / 10 min, preferably 0.5 g / 10 min to 1.5 g / 10 min, DIN 53 479, Method A, or density measured at 23 ° C. according to ISO 1183 is 0.935 g / cm 3 to 0.97 g / cm 3, preferably 0.94 g / cm 3 to 0.96 g / cm 3, and DSC (maximum of melting curve, The heating rate is preferably high density polyethylene (HDPEs) having a melting point of 20 ° C./min) between 120 ° C. and 150 ° C., preferably between 125 ° C. and 135 ° C.

For the present invention, the melt flow index MFI measured at 21.6 N / 190 ° C. according to ISO 1133 is 0.1 g / 10 min to 3.0 g / 10 min, preferably 0.6 g / 10 min to 1.5 g / 10 min, DIN 53 479, Method A, or density measured at 23 ° C. according to ISO 1183 is 0.925 g / cm 3 to 0.94 g / cm 3, preferably 0.925 g / cm 3 to 0.935 g / cm 3, and DSC (maximum value of melting curve, The heating rate is preferably medium density polyethylene (MDPEs) having a melting point of 115 ° C. to 145 ° C., preferably between 115 ° C. and 130 ° C., measured at 20 ° C./min).

For the present invention, the melt flow index MFI measured at 21.6 N / 190 ° C. according to ISO 1133 is 0.1 g / 10 min to 3.5 g / 10 min, preferably 0.5 g / 10 min to 2.0 g / 10 min, DIN 53 479, Method A, or density measured at 23 ° C. according to ISO 1183 is 0.91 g / cm 3 to 0.925 g / cm 3, preferably 0.915 g / cm 3 to 0.925 g / cm 3, and DSC (maximum value of melting curve, The heating rate is preferably low density polyethylene (LDPEs) having a melting point between 110 ° C. and 135 ° C., preferably between 110 ° C. and 125 ° C., measured by 20 ° C./min).

Cycloolefin polymers (COPs) are homopolymers made from one type of cycloolefin or copolymers (COCs) made from cycloolefins and comonomers, where the content of comonomers is based on the weight of the cycloolefin polymer Up to 50% by weight. Cycloolefins are mono or polyunsaturated polycyclic ring systems such as cycloalkenes, bicycloalkenes, tricycloalkenes or tetracycloalkenes. The ring system may be single or polysubstituted.

Among the COPs described above, those prepared from monoalkylated or unsubstituted cycloolefins are preferred. Particularly preferred cycloolefin homopolymers are polynorbornene, polydimethyloctahydronaphthalene, polycyclopentene and poly (5-methyl) norbornene. The cycloolefin polymer may be branched. This type of product may have a comb or star structure.

If desired, the cycloolefins described above may be copolymerized with comonomers. Such cycloolefin copolymers (COCs) comprise up to 50% by weight, preferably 1% to 35% by weight, more preferably 5% to 25% by weight comonomer, based on the weight of the COC. Preferred comonomers are olefins having 2 to 6 carbon atoms, in particular ethylene and butylene.

Cycloolefin polymers can be prepared with the aid of transition metal catalysts. The manufacturing process is described, for example, in DD-A-109 225, EP-A-0 407 870 and EP-A-0 485 893, which are expressly incorporated herein by reference.

The ordered polypropylene is a homopolymer or copolymer having a propylene content of at least 70% by weight, preferably greater than 80% by weight, more preferably 95% to 100% by weight, based on the total weight of the polymer. The isotacticity of the propylene content of the polymer is less than 15% by weight, preferably less than 6% by weight. The average order length for the ordered arrays is greater than 20%, preferably greater than 25%. Suitable comonomers of the copolymer are olefins having 2 to 8 carbon atoms, with ethylene and / or butylene being preferred.

Polypropylene and incompatible polyolefins are used as mixtures or blends. For the purposes of the present invention, a mixture means a mechanical mixture made from each component. To this end, each component is generally poured together into small sized compacted castings such as lenticular or spherical particulates and mechanically mixed using a suitable shaking device.

For the purposes of the present invention, the blend is an alloy-like compound for each component that can no longer be separated into the original component. Blends have the same properties as homogeneous materials and can be similarly characterized with appropriate parameters.

According to the invention, the surface of the top layer A is rougher than the opposite film surface. It has been found that rough surfaces are essential for the processing habit of the film in the method of use according to the invention. Due to the smooth opposite surface C, this film tends to block. In addition, winding-up is a big problem when the surface is smooth. According to the prior art, an antiblocking agent is mixed in one of the top layers to avoid this problem. It has been found that mixing the antiblocking agent in the uppermost layer A is disadvantageous for the method of use according to the invention. The embodiment including the antiblocking agent in the top layer A damages the ceramic layer because the antiblocking agent in the top layer A may leave traces or migrate to the ceramic layer when the coated film is wound. Ceramic layers damaged in this way can no longer be used to manufacture capacitors.

In order to facilitate the processing of the film without blocking agents and to avoid damaging the ceramic layer, the surface roughness of the top layer A is produced according to the invention by a mixture of polypropylene and incompatible polyolefin. Surprisingly, the surface structure produced in this way is rough enough to allow the film to be processed well, even though the opposite surface is smooth. The film can be wound and unrolled without any problem without mechanically removing the incompatible polymer mixed in the top layer matrix.

In contrast to inorganic pigments commonly used to achieve a constant surface roughness, the rough surface structure of the film according to the invention does not cause any damage or surface deformation to the ceramic layer at all during winding or unrolling (especially the low hardness of incompatible polymers). Due to). The method of use according to the invention thus makes it possible to produce thin ceramic layers which preferably have a smooth surface and are free of any defects or other damage.

The thickness of the uppermost layer A is larger than 0.3 µm, preferably 0.4 µm to 3 µm, more preferably 0.6 µm to 1.5 µm.

According to the invention, the opposite surface of the film is smoother than the surface of the top layer A. This smooth surface may be the surface of the base layer. In a preferred embodiment, the film has a second top layer C, which results in a smoother surface.

The top layer C consists essentially of the polyolefin, preferably the propylene polymer and, if desired, additives added in an effective amount in each case. Top layer C generally comprises at least 90% by weight, preferably less than 95% to 100% by weight of polyolefin.

Examples of olefin polymers of this type

Propylene homopolymer or

Ethylene and propylene or

Ethylene and 1-butylene or

Of propylene and 1-butylene

Copolymer or

Of ethylene, propylene and 1-butylene

Terpolymer or

Particularly preferably,

The content of ethylene is 1% to 10% by weight, preferably 2.5% to 8% by weight.

Random ethylene-propylene copolymer or

The content of butylene is 2 to 25% by weight, preferably 4 to 20% by weight.

Random propylene-1-butylene copolymer (in each case based on the total weight of the copolymer) or

The content of ethylene is 1% to 10% by weight, preferably 2% to 6% by weight,

The content of 1-butylene is 2% to 20% by weight, preferably 4% to 20% by weight,

It is a random ethylene-propylene-1-butylene terpolymer (in each case based on the total weight of the terpolymer).

Suitable polypropylene homopolymers comprise predominantly (at least 90%) propylene and have a melting point of at least 140 ° C., preferably between 150 ° C. and 170 ° C., with a content that is soluble in n-heptane based on the homogeneous homopolymer. Preferred homogeneous polypropylenes of up to 6% by weight are preferred. In general, the melt flow index of the homopolymer is from 0.5 g / 10 min to 15 g / 10 min, preferably from 1.5 g / 10 min to 10 g / 10 min, at a load of 230 ° C. and 21.6 N (DIN53 735).

The melt flow index of the copolymers and / or terpolymers described above used in the uppermost layer C is generally from 1.5 g / 10 min to 30 g / 10 min, preferably from 3 g / 10 min to 15 g / 10 min. The melting point is in the range of 120 ° C to 140 ° C. All melt flow indices given above were measured at a load of 230 ° C., 21.6 N (DIN53 735).

As part of the method of use according to the invention, the smoother surface of the top layer C is provided with a ceramic coating. It has been found that there is adequate adhesion to the polyolefin surface in order to allow a thin layer of ceramic material to be applied. At the same time, however, the adhesion between the surface of the film and the ceramic layer is sufficiently low that, after the corresponding drying and / or processing steps, the support film is separated from the ceramic layer without damaging the ceramic layer produced in this way. Embodiments with homopolymer top layers have proved particularly advantageous, since the thermal resistance of the homopolymer is greater than that of the copolymer or terpolymer, allowing higher temperatures for drying and / or processing in the manufacture of ceramic layers. Because. In addition, it has been found that the ceramic layer can be separated from the support layer with the homopolymer top layer with little trouble.

Top layer C may include conventional neutralizers, stabilizers, antistatic agents and lubricants, if desired. For the method of use according to the invention it is essential that the top layer C does not contain any antiblocking agent to increase the surface roughness. The increased surface roughness will migrate to the surface of the ceramic layer during coating. However, the ceramic layer should have as smooth a surface as possible to be used as a dielectric free of defects and air bubbles. In addition, it has been found that the particles of the antiblocking agent stick to the ceramic layer during the removal of the support film! This is very undesirable because the particles of the antiblocking agent in the ceramic layer cause electrical defects and air bubbles.

The thickness of the uppermost layer C is larger than 0.3 µm, preferably 0.4 µm to 3 µm, more preferably 0.6 µm to 1.5 µm.

The total thickness of the multilayer polyolefin film according to the invention can vary within wide ranges and depends on the intended use. The total thickness is between 6 μm and 70 μm, preferably between 10 μm and 50 μm, with the base layer accounting for about 50% to about 98% of the total film thickness.

In order to further improve the specific properties of the polyolefin film, both the base layer and the top layer (s) are in each case an effective amount of additional additives, preferably antistatic and / or lubricants and / or stabilizers and / or neutralizing agents. It may include. All amounts of data listed below are in weight percent (% by weight) and are in each case based on the layer or layers to which the additive may be added.

Preferred antistatic agents are alkali metal alkanesulfonates, polyether-modified, ie ethoxylated and / or propoxylated polydiorganosiloxanes {polydialkylsiloxanes Polyalkylphenylsiloxanes and the like} and / or essentially straight-chain saturated aliphatic comprising aliphatic radicals having 10 to 20 carbon atoms substituted with ω-hydroxy- (C ₁ -C ₄ ) alkyl groups Tertiary amines wherein N, N-bis (2-hydroxyethyl) alkylamines are particularly suitable having from 10 to 20 carbon atoms, preferably from 12 to 18 carbon atoms, in the alkyl radical. Effective amounts of antistatic agents range from about 0.05% to about 0.3% by weight.

Lubricants are higher aliphatic acid amides, higher aliphatic acid esters, waxes and metal soaps as well as polydimethylsiloxanes. Effective lubricant amounts are from 0.1% to 3% by weight. Particularly suitable is the addition of higher aliphatic acid amides in the range from 0.15% to 0.25% by weight to the base layer and / or top layer A. Particularly suitable aliphatic acid amides are erucamides. The polydimethylsiloxane is preferably added at 0.3% by weight to 2.0% by weight, particularly when the polydimethylsiloxane has a viscosity of 10,000 to 1,000,000 mm ² / s.

Stabilizers that can be used are conventional compounds which have a stabilizing action on ethylene, propylene and other α-olefin polymers. The amount of the stabilizer added is 0.05% by weight to 2% by weight. Particularly suitable stabilizers are phenolic stabilizers, alkali metal or alkaline earth metal stearates and / or alkali metal or alkaline earth metal carbonates. Phenolic stabilizers are suitable in the range from 0.1% to 0.6% by weight, in particular from 0.15% to 0.3% by weight and have a molecular weight of at least about 500 g / mol. Pentaerythrityl tetrakis-3- (3,5-di-tert-butyl-4-hydroxyphenyl) pentaerythrityl tetrakis-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate propionate} or 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene {1,3,5-trimethyl-2,4, 6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene} is particularly advantageous. Also preferred is alkaline earth metal stearate and / or carbonate added in an amount of 0.01% to 0.05% by weight, in particular the average particle size is less than 0.1 mm, preferably 0.03 mm to 0.07 mm, the absolute particle size Calcium stearate and / or calcium carbonate having a specific surface area of less than 5 μm and at least 40 m 2 / g.

As part of the study of the present invention, the film may be used for the application of photoresist. The photoresist layer is generally applied to a suitable film material and wound with this support film. In some cases, the adhesion between the support film and the applied photoresist layer is so large that problems can occur continuously during unwinding and continuous processing. It has been found that the film described above can advantageously be inserted into a reel as a separating film to prevent adhesion between the support film and the photoresist layer.

In order to produce a multilayer film by the known coextrusion process, the melt corresponding to each layer of the film is coextruded through a flat-film die and one or more for solidification. The film produced on the roll is peeled off, the film is then biaxially stretched (oriented), and the biaxially stretched (oriented) film is heat stabilized. -set) and wind up.

The biaxial stretching (orientation) operation may be performed simultaneously or sequentially, with sequential biaxial stretching being performed first in the longitudinal axis direction (machine direction) and then in the transverse axis direction (direction perpendicular to the machine). Do.

First, as has conventionally been done in a coextrusion process, the polymer or polymer mixture or blend of each layer is compressed and liquefied in an extruder, which optionally may be added to the polymer beforehand. The melt then passes simultaneously through a flat film die (slot die) and the extruded multilayer film is stripped over one or more take-off rolls while cooling and solidifying.

The film obtained in this way is then stretched in the longitudinal and transverse directions relative to the extrusion direction, which causes the molecular chains to align. Longitudinal stretching is preferably performed at a ratio of 4: 1 to 7: 1, and transverse stretching is preferably performed at a ratio of 8: 1 to 10: 1. Longitudinal stretching can be advantageously performed by two rolls rotating at different speeds in accordance with the desired stretching ratio, and transverse stretching is advantageously carried out by means of a suitable tenter frame. Can be.

There is a thermal stabilization operation (heat treatment operation) after stretching the biaxial film, in which the film stays at about 0.5 seconds to about 10 seconds at 150 ° C to 160 ° C. The film is then wound in a conventional manner by a wind-up unit.

It has proven to be particularly advantageous to maintain take-off rolls or rolls in which the extruded film is cooled and solidified at elevated temperatures, as compared to 10 ° C. to 60 ° C. in the prior art through heating and cooling circuits.

In addition, biaxial stretching may also be advantageously carried out at elevated temperature, wherein stretching in the longitudinal direction is preferably carried out at 90 ° C to 140 ° C and stretching in the transverse direction is preferably carried out at 150 ° C to 190 ° C.

Moreover, the invention relates to a process for producing a ceramic capacitor in which the film described above is used according to the invention. For this purpose, first, the ceramic starting material, which is usually a ceramic powder, is transformed into a high viscosity composition using a suitable solvent and binder. Suitable ceramic materials are, for example, metal oxides and / or titanates such as barium titanate, magnesium silicate, titanium dioxide, bismuth oxide and mixtures thereof. This ceramic is distinguished by a high dielectric constant. The highly viscous, ceramic coating composition is applied to the smooth surface C of the film and dried. The film coated in this way is then wound up. The ceramic surface can be metallized in subsequent processing steps if desired. This film is finally separated from the ceramic layer. The ceramic layer produced in this way is subsequently transformed into a ceramic capacitor in a manner originally known.

The invention is now described in more detail with reference to examples.

<Example 1>

A three layer film having an ABC layer structure is extruded from the slot die by coextrusion at an extrusion temperature of 250 ° C.

The base layer consists essentially of propylene homopolymer having a melting point of 163 ° C. with a content of 4.5% by weight dissolved in n-heptane. The melt flow index of the propylene homopolymer is 3.3 g / 10 min at 230 ° C. with a load of 21.6 N (DIN 53 735, ISO 1133). The base layer is 0.13% by weight of pentaerythryl tetrakis-4- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate for stabilization. -tert-butyl-4-hydroxyphenyl) propionate} (registered trademark) Irganox 1010} and 0.06% by weight of calcium stearate as a neutralizing agent. Furthermore, the base layer is 0.14% by weight of N, N-bis (2-hydroxyethyl) (C ₁₀ -C ₂₀ ) alkylamine {registered trademark Armostat 300} and 0.2% by weight of erucamide as lubricant. Armoslip).

Top layer A consists essentially of a mixture of 93% by weight propylene homopolymer and 7% by weight LDPE. The propylene homopolymer had a content of 5% by weight in n-heptane, a melting point of 164 ° C, and a melt flow index of 8.0g / 10min with a load of 230 ° C and 21.6N (DIN 53 735, ISO 1133). Propylene homopolymers contained 0.05% by weight of Irgafos 168 {tris (2,4-di-tert-butyl phenyl phosphite) and 0.07% by weight of Irganox 1010 and 0.06% by weight as a neutralizing agent LDPE had a melting point of 113 ° C. (DSC), a melt flow index of 0.85 g / 10 min with a load of 190 ° C. and 21.6 N (DIN 53 735, ISO 1133) and a density of 0.923 g / Cm 3.

Top layer C consists essentially of (for example about 100% by weight) propylene homopolymer. The propylene homopolymer had a content of 5% by weight in n-heptane, a melting point of 164 ° C, and a melt flow index of 8.0g / 10min with a load of 230 ° C and 21.6N (DIN 53 735, ISO 1133). Propylene homopolymers contained 0.05% by weight of Irgafos 168 {tris (2,4-di-tert-butyl phenyl phosphite)} and 0.07% by weight of Irganox 1010 and 0.06% by weight of neutralizing agent % Calcium stearate was included.

After coextrusion, the extruded three layers of film are peeled off and cooled on the first take off roll and the next take off roll, then preheated, stretched in the longitudinal direction, stretched in the transverse direction, and in the corresponding process steps. Stabilized and wound, the following conditions are selected.

Extrusion: Extrusion Temperature 250 ℃

The temperature of the 1st take off roll 35 degreeC

Temperature of take-up roll 29 ℃

Longitudinal stretching: preheating area T = 145 ° C

Stretch Roll T = 145 ° C

4.6 times longitudinal stretching

Transverse stretching: Heated field T = 182 ° C

Stretch Field T = 162 ° C

9.2x transverse stretching

Stabilization: Temperature T = 120 ℃

The thickness of the film is about 45 μm, the thickness of the base layer is 43 μm and the thickness of each top layer is 1.0 μm.

Comparative Example 1

Example 1 is repeated. As compared with Example 1, only the composition of the uppermost layer A was changed. Top layer A consisted substantially of the top layer homopolymer described in Example 1. In addition, the top layer contained 0.38 wt% of an antiblocking agent (Sylobloc 45) containing SiO ₂ having an average particle diameter of 4.8 μm. Process conditions were not substantially changed.

The film according to the embodiment according to the invention is very suitable as a support film for ceramic coating. This film can be well coated. After drying the ceramic layer can be peeled off very well and has a smooth surface without defects. Electron micrographs show that the surface of the top layer A has a uniform roughness, while the surface A of the film according to the comparative example shows dispersed particles (antiblocking agents) protruding from the top layer. This elevation is compressed in an undesirable way through the opposite side onto the surface of the ceramic coating. In this case, undesirable defects are formed in the ceramic layer.

The following table shows other properties of the polyolefin films in the examples and the comparative examples.

Film properties unit Example Comparative example Modulus of elasticity, longitudinal axis N / mm2 2186 2349 Modulus of elasticity, abscissa N / mm2 4701 4659 Tear strength, longitudinal direction N / mm2 148 131 Tear strength, transverse direction N / mm2 358 306 Elongation at rupture, longitudinal direction % 262 253 Elongation at break, horizontal axis direction % 54 45 Roughness Rz of the top layer A surface Μm 0.56 0.72 Roughness Rz of the top layer C surface Μm 0.3 0.33 Roughness Rmax of the top layer A surface Μm 0.64 1.41 Roughness Rmax of the top layer C surface Μm 0.37 0.41 Slip friction of A against C 0.33 0.45

The following measurements were used to characterize the raw materials and films.

Melt flow index

DIN 53 735 at 230 ° C with a load of 21.6 N

Melting point

DSC measurement, maximum of melting curve, heating rate 20 ° C / min

asperity

Roughness was determined by Rz and Rmax values using a cut-off of 2.5 mm according to DIN 4768.

Friction

Slip friction was determined according to DIN 53 375 at 23 ° C.

Modulus of elasticity

Modulus of elasticity was determined according to EN ISO 521-1 on samples of size 15 * 100 mm 2 on the first 10 days after preparation.

Tear strength, elongation at break

Tear strength and elongation at break were determined according to EN ISO 521-1 for samples of size 15 * 100 mm2.

Shrinkage

The shrinkage values in the longitudinal and transverse directions are related to the respective elongation lengths (vertical axis direction L ₀ and horizontal axis direction T ₀ ) of the film before the shrinkage process. The longitudinal axis direction is the machine direction and the horizontal axis direction is defined as the direction transverse to the machine direction. Samples of 10 * 10 cm 2 are shrunk in a fan-assisted oven at each temperature (100 ° C. to 140 ° C.) for 15 minutes. Then, the contracted and remaining stretched length of the sample is determined again in the longitudinal and transverse directions (L ₁ and T ₁ ). The percent shrinkage is then expressed as the product of the difference in measured elongation lengths divided by the original lengths L ₀ and T ₀ times 100.

Shrinkage in longitudinal direction

Shrinkage in the transverse direction

This determination method for shrinkage in the longitudinal and transverse directions is according to DIN 40634.

density

Density was determined according to DIN 53479, Method A.

As described above, the present invention can be used in a biaxially oriented multilayer polyolefin film used as a support film for a ceramic layer, and can be used in a process for manufacturing a ceramic capacitor.

Claims (8)

A method of using an oriented polyolefin multilayer film as a support film in the manufacture of a ceramic capacitor, The multilayer film consists of a base layer and at least one top layer A, wherein the top layer A comprises a propylene polymer and at least one incompatible polyolefin, wherein the incompatible polyolefin is LDPE, HDPE , MDPE, ethylene-propylene copolymers or cycloolefin polymers or syndiotactic polymers The surface of the top layer A has a greater roughness than the surface opposite the film, The film is provided with a ceramic coating on a smoother surface of the film, the coating being dried and then separated from the support film Characterized in that the method of using the oriented polyolefin multilayer film. The method of claim 1, wherein the uppermost layer A does not contain any antiblocking agent of particulates. 3. The use of oriented polyolefin multilayer film according to claim 1, wherein the film has a second top layer C and the surface of the top layer C forms a smoother surface. 4. Way. 4. The method of claim 1, wherein the uppermost layer C comprises substantially propylene homopolymers and does not contain any antiblocking agents. 5. 5. The method according to claim 1, wherein the uppermost layer A comprises the propylene polymer in an amount of 70 wt% to 99.5 wt% and the incompatible polyolefin in an amount of 0.5 wt% to 30 wt%. A method of using an oriented polyolefin multilayer film, characterized in that it comprises a. 6. The method of claim 1, wherein the film coated with a ceramic layer is provided with a metal layer on the surface of the ceramic layer. 7. A ceramic capacitor manufactured by the method of use according to at least one of claims 1 to 5. A method of using an oriented polyolefin multilayer film as a support film in preparing a photoresist layer, The multilayer film consists of a base layer and at least one top layer A, wherein the top layer A comprises a propylene polymer and at least one incompatible polyolefin, wherein the incompatible polyolefin is an LDPE, HDPE, MDPE, ethylene-propylene airborne Are copolymers or cycloolefin polymers or ordered polymers, The surface of the top layer A has a greater roughness than the opposite surface of the film, As a separation film the film is brought into contact with the photoresist layer with a smoother surface of the film. Characterized in that the method of using the oriented polyolefin multilayer film.