Capacitor composition containing polypropylene and cyclic olefin polymer

Abstract

The present invention relates to a polypropylene composition comprising a high isotactic homopolymer of propylene in an amount of 70 to 95% by mass relative to the total mass of the polypropylene composition, and a cyclic olefin polymer composition in an amount of 5 to 30% by mass relative to the total mass of the polypropylene composition, wherein the cyclic olefin polymer composition comprises at least a first cyclic olefin polymer and a second cyclic olefin polymer, and the glass transition temperature of the first cyclic olefin polymer is less than 140°C. The present invention further relates to a cast film comprising the polypropylene composition and a biaxially oriented film comprising the polypropylene composition. The present invention also provides a capacitor comprising the biaxially oriented film.

Description

[Technical Field]

[0001] The present invention relates to a polypropylene composition comprising a high isotactic homopolymer of propylene in an amount of 70 to 95% by mass relative to the total mass of the polypropylene composition, and a cyclic olefin polymer composition in an amount of 5 to 30% by mass relative to the total mass of the polypropylene composition, wherein the cyclic olefin polymer composition comprises at least a first cyclic olefin polymer and a second cyclic olefin polymer, and the glass transition temperature of the first cyclic olefin polymer is less than 140°C. The present invention further relates to a cast film comprising the polypropylene composition and a biaxially oriented film comprising the polypropylene composition. The present invention also provides a capacitor comprising the biaxially oriented film. [Background technology]

[0002] Polypropylene is an excellent dielectric material used in a variety of capacitor film applications. However, known polypropylene capacitor grades have a limited maximum operating temperature, which is a challenge. New generations of inverters, such as traction inverters for electric mobility and inverters for renewable energy sources like solar and wind power, require higher temperature tolerance for their capacitor films. The higher maximum operating temperature required, or in other words, the greater durability at the required temperature levels, has been addressed in various ways so far. Patent Document 1 proposes combining polypropylene with composite rubber powder in a mass ratio of 100:0.01 to 2.0. The particle size of the composite rubber powder is 20 to 100 nm and consists of silicone rubber powder and a nucleating agent in a mass ratio of 99:1 to 90:10. This is prepared by mixing silicone rubber latex obtained by irradiation vulcanization with an aqueous solution or emulsion of the nucleating agent. Patent Document 2 teaches that high temperature resistance can be achieved by combining beta nucleation of high-purity polypropylene with long-chain branched polypropylene. More specifically, the present invention provides a polypropylene composition comprising 95.0 to 99.9% by mass of propylene homopolymer having a specific melt flow rate and extremely low ash content, 0.1 to 5.0% by mass of long-chain branched polypropylene, and a beta nucleating agent up to 1000 ppm. Patent documents 3 and 4 suggest that it may be preferable to blend polypropylene with a specific amount of a specific cyclic olefin copolymer to obtain a material suitable for high-temperature capacitor applications. In this regard, Patent document 3 relies on an ethylene norbornene copolymer having a specific norbornene content, while Patent document 4 suggests a cyclic olefin polymer having a glass transition temperature of 120 to 170°C. However, the above approach necessitates sacrificing other important properties in order to improve the temperature resistance of the capacitor polypropylene composition. For example, mechanical properties such as low shrinkage and high rigidity, as well as resistance to high voltage, are sacrificed to some extent. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Chinese Patent Application Publication No. 101724195 Specification [Patent Document 2] European Patent Application Publication No. 2995641 [Patent Document 3] International Publication No. 2018 / 210854 Brochure [Patent Document 4] International Publication No. 2018 / 197034 Pamphlet [Overview of the project] [Problems that the invention aims to solve]

[0004] Therefore, there is still a need to improve and set the characteristics for capacitor applications, that is, to provide a polypropylene composition with high temperature resistance, high dielectric breakdown strength, and appropriate mechanical properties. Accordingly, an object of the present invention is to overcome the above problems of known compositions and to provide a polypropylene composition that meets these needs. Another object of the present invention is to provide a polypropylene film with excellent performance for capacitor applications. Finally, the present invention aims to improve the specifications of capacitors. Furthermore, capacitor films need to have high dielectric breakdown strength, as well as good mechanical properties such as low shrinkage and high rigidity. [Means for solving the problem]

[0005] The above objectives are achieved by a polypropylene composition having the features of claim 1, a cast film having the features of claim 10, a biaxially oriented film having the features of claim 14, and a capacitor having the features of claim 15. The present invention relates to a polypropylene composition comprising a high isotactic homopolymer of propylene in an amount of 70 to 95% by mass relative to the total mass of the polypropylene composition, and a cyclic olefin polymer composition in an amount of 5 to 30% by mass relative to the total mass of the polypropylene composition, wherein the glass transition temperature measured according to ISO 11357 is in the range of 140 to 155°C, wherein the cyclic olefin polymer composition comprises at least a first cyclic olefin polymer and a second cyclic olefin polymer, and the glass transition temperature of the first cyclic olefin polymer is less than 140°C as measured according to ISO 11357. Preferably, the glass transition temperature of the first cyclic olefin polymer is less than 60 to 140°C, for example, less than 100 to 140°C as measured according to ISO 11357. Furthermore, the glass transition temperature of the second cyclic olefin polymer is at least 155°C as measured according to ISO 11357. Preferably, the glass transition temperature of the second cyclic olefin polymer is at least 155 to 190°C, as measured according to ISO 11357.

[0006] In one embodiment, the polypropylene composition comprises a highly isotactic homopolymer of propylene in an amount of 75 to 90% by mass, preferably 79 to 86% by mass, more preferably 81 to 86% by mass, based on the total mass of the polypropylene composition, and a cyclic olefin polymer composition in an amount of 10 to 25% by mass, preferably 14 to 21% by mass, more preferably 14 to 19% by mass, based on the total mass of the polypropylene composition. Selecting a cyclic olefin polymer composition having a glass transition temperature in a very specific narrow range of 140 to 155°C and combining it with a highly isotactic homopolymer of propylene is technically advantageous. On the other hand, the glass transition temperature range of the propylene composition of the present invention is wider compared to a pure highly isotactic homopolymer of propylene. This provides favorable mechanical properties, facilitating the processing of the composition into a film for capacitor applications. On the other hand, the polypropylene composition according to the present invention exhibits excellent structural stability and dielectric stability at high temperatures.

[0007] In a preferred embodiment, the polypropylene composition is obtained by melt-blending a highly isotactic homopolymer of propylene and a cyclic olefin polymer composition. The apparatus capable of performing melt-blending can be selected from the group consisting of a kneader, a mill, and an extruder. Further, the cyclic olefin polymer composition itself can be obtained by melt-blending at least two different cyclic olefin polymers. In contrast to the dry blending method, a highly uniform polypropylene composition can be produced by the melt blending method. By selecting the content of the cyclic olefin polymer composition to be 5 to 30% by mass, the cyclic olefin polymer composition is finely and uniformly dispersed in the matrix of the highly isotactic homopolymer of propylene. Generally, the dispersion state of the cyclic olefin polymer composition is considered to affect the mechanical and electrical properties of the propylene composition. The dimensions and shape of the domains formed by the cyclic olefin polymer composition in the dispersion can be analyzed using an atomic force microscope (AFM) or other types of microscopes. Taking the above into consideration, when a 250-μm-thick non-oriented cast film made of a polypropylene composition is analyzed by AFM, the maximum dimension of the domains of the cyclic olefin polymer is preferably more than 50% (d50), particularly more than 90% (d90), for example 95% (d95), and is smaller than 2.0 μm.

[0008] Cyclic olefin polymer composition The cyclic olefin polymer composition is preferably a thermoplastic composition. The cyclic olefin polymer composition may include a blend of one type of cyclic olefin polymer or at least two different types of cyclic olefin polymers, or may consist essentially of them. The term "cyclic olefin polymer" is understood to be a polymer containing cyclic olefin units. The cyclic olefin polymer may be a cyclic olefin homopolymer or a cyclic olefin copolymer.

[0009] The term "copolymer" in the present invention refers to a polymer prepared from at least two different monomers. In other words, the term "copolymer" also includes terpolymers and copolymers having four or more different monomer units. Therefore, a cyclic olefin polymer may be a copolymer containing a first monomer unit which is a cyclic olefin unit and at least one second monomer unit different from the first monomer unit, such as an acyclic olefin unit. A cyclic olefin copolymer containing at least a first cyclic olefin unit and a second cyclic olefin unit different from the first cyclic olefin unit is equally included by the term "cyclic olefin polymer". The cyclic olefin polymer can be obtained by either ring-opening polymerization or ring-maintaining polymerization of at least one kind of cyclic olefin monomer. Among these, the cyclic olefin polymer obtained by ring-maintaining polymerization is preferred.

[0010] In a more preferred embodiment, at least one kind of cyclic olefin monomer is selected from the group consisting of cyclopentadiene, tetracyclododecene, norbornene and derivatives of the above compounds. Norbornene and its derivatives are particularly preferred examples of at least one kind of cyclic olefin monomer. Norbornene and its derivatives preferably have the following formula (I):

[0011] [Chemical formula] (In the formula, n is 0 or 1, m is 0 or an integer, particularly 0 or 1, R 1 、R 2 、R 3 、R 4 、R 5 、R 6 are each independently selected from the group consisting of hydrogen, halogen, alkyl group, cycloalkyl group, aryl group and alkoxy group, R 7 、R 8 、R 9 、R 10 、R11 , R 12 , R 13 , R 14 , R 15 , R 16 These are independently selected from the group consisting of hydrogen and alkyl groups, R 17 , R 18 , R 19 , R 20 R is independently selected from the group consisting of hydrogen, halogen, alkyl, cycloalkyl and aryl groups, where R 17 and R 19 Alternatively, it may form a cyclic ring or cyclic system, where the cyclic ring or cyclic system may be saturated or unsaturated. It is a compound represented by [formula]. Further and equally preferred examples of norbornene derivatives are given by the following formula (II):

[0012] [ka] (In the formula, R 21 and R 22 These are independently selected from the group consisting of hydrogen, C5-C7 cycloalkyl groups, C5-C7 aryl groups, and C1-C4 alkyl groups, R 23 and R 24 (These are independently selected from the group consisting of hydrogen and C1-C4 alkyl groups.) It is a compound represented by [formula].

[0013] The acyclic olefin monomer may be an α-olefin. Non-limiting examples of α-olefins are C2-C8 α-olefins, such as α-olefins selected from the group consisting of ethylene, propylene, 1-butene, 2-methyl-1-propene (isobutylene), and 3-methyl-1-butene. Preferred α-olefins are linear C2-C8 α-olefins such as ethylene and propylene. Particularly preferred is ethylene as the α-olefin.

[0014] In one embodiment, the cyclic olefin polymer composition comprises, consists of, or essentially comprises at least one cyclic olefin copolymer, preferably selected from the group consisting of norbornene-ethylene copolymer and tetracyclododecene-ethylene copolymer or a blend of at least two of the cyclic olefin copolymers. In a particularly preferred embodiment, the cyclic olefin polymer composition comprises, or essentially comprises one norbornene-ethylene copolymer or a blend of two norbornene-ethylene copolymers with different norbornene content. Furthermore, non-limiting examples of cyclic olefin polymers are polymers commercially available as APEL® from Mitsui Chemicals or TOPAS® from TOPASAdvancedPolymers.

[0015] The glass transition temperature (hereinafter also referred to as "Tg") of a cyclic olefin polymer composition may be controlled by the type of monomer used, for example, by at least one type of cyclic olefin monomer, and, if present, by the type of acyclic olefin monomer. If the cyclic olefin polymer composition is a blend of at least two types of cyclic olefin polymers, the mass ratio of the cyclic olefin polymers also affects the glass transition temperature of the composition. Furthermore, if the cyclic olefin polymer composition is a composition containing at least one cyclic olefin copolymer, the amount of cyclic olefin monomer may be used to individualize the glass transition temperature of the entire composition. It is known that increasing the norbornene content, for example, in norbornene-ethylene copolymers can raise the glass transition temperature. The same applies to other combinations of cyclic olefin monomers and acyclic olefin monomers.

[0016] The cyclic olefin polymer composition may contain cyclic olefin units, such as norbornene units, in an amount of 70-90% by mass, 75-85% by mass, or 75-80% by mass, and acyclic olefin units, such as ethylene units, in an amount of 10-30% by mass, 15-25% by mass, or 20-25% by mass, relative to the total mass of the cyclic olefin polymer composition (B). In preferred embodiments, the glass transition temperature of the cyclic olefin polymer composition may be in the range of 140 to 150°C, for example, 140 to 144°C, and particularly 140 to 143°C. In other preferred embodiments, the glass transition temperature of the cyclic olefin polymer composition may be in the range of 145 to 155°C. The first cyclic olefin polymer and the second cyclic olefin polymer may be melt-blended, preferably in a mass ratio of 1:5 to 5:1, and particularly in a mass ratio of 1:3 to 3:1, to form a cyclic olefin polymer composition. Using two cyclic olefin polymers with different glass transition temperatures broadens the glass transition temperature range of the polypropylene composition, thus contributing to an expansion of the processing window for the polypropylene composition. Furthermore, using two cyclic olefin polymers with different glass transition temperatures allows for better control of the material's high-temperature performance. The cyclic olefin polymer composition preferably has an MFR2 (260°C, 2.16 kg) measured according to ISO 11357, which is 2 to 50 g / 10 min, preferably 8 to 25 g / 10 min.

[0017] High-isotactic propylene homopolymer The term "propylene homopolymer" as used in this invention refers to polypropylene consisting substantially, i.e., at least 99.5% by mass, more preferably at least 99.8% by mass, of propylene units. Preferably, as described in the Examples section below, only propylene units are used. 13 It can be detected in propylene homopolymers by 13C NMR spectroscopy. The highly isotactic homopolymer of propylene is preferably linear polypropylene, i.e., polypropylene without detectable amounts of branching of long or short chains.

[0018] In preferred embodiments of the present invention, a highly isotactic homopolymer of propylene is 13 Quite high pentad isotacticity, as measured by 13C NMR. <mmmm>Characterized by the following: More specifically, the isotactic pentad fraction of the high isotactic homopolymer of propylene may be 93-99.5%, preferably 95-99.0%, and more preferably 96-98.5%. In certain embodiments, the pentad isotacticity of the high isotactic homopolymer of propylene is in the range of 96.0-98.5%, and more preferably 97.0-98.0%. Preferably, high isotacticity is accompanied by high crystallinity of the material. Furthermore, preferably, high isotacticity is accompanied by a low cold xylene soluble component (XCS) content. Therefore, in a more preferred embodiment of the present invention, the high isotactic homopolymer of propylene of the present invention is characterized by a considerably low XCS content, i.e., an XCS content of 2.0% by mass or less, more preferably 1.8% by mass or less, and even more preferably 1.6% by mass or less. Therefore, it is particularly understood that the XCS content of the propylene high isotactic homopolymer of the present invention is in the range of 0.3 to 2.0% by mass or less, more preferably in the range of 0.3 to 1.8% by mass or less, and even more preferably in the range of 0.4 to 1.6% by mass or less. Preferably, the XCs content refers to the XCs content determined at 23°C according to ISO 6427. It is further understood that the XCS content indicates that the high isotactic homopolymer of propylene preferably does not contain elastomer polymer components such as ethylene propylene rubber. In other words, the high isotactic homopolymer of propylene does not correspond to heterophase polypropylene, i.e., a system consisting of a polypropylene matrix in which the elastomer phase is dispersed. Such systems are usually characterized by a considerably high cold xylene soluble content.

[0019] Alternatively, or furthermore, the high isotactic homopolymer of propylene of the present invention preferably has a specific range of melt flow rates. For example, the MFR2 (230°C) of the high isotactic homopolymer of propylene may be 0.4 to 10 g / 10 min, preferably 0.5 to 5 g / 10 min, as measured according to ISO 1133. In a particularly preferred embodiment, the MFR2 (230°C) of the high isotactic homopolymer of propylene is 2.0 to 4.5 g / 10 min as measured according to ISO 1133. Here, MFR2 (230°C) refers to the melt flow rate measured at 230°C under a 2.16 kg load.

[0020] Furthermore, the high isotactic homopolymer of propylene has an ash content of preferably 60 ppm or less, more preferably 30 ppm or less, and even more preferably 20 ppm or less. Preferably, the ash content is in the range of 5 to 30 ppm, particularly in the range of 10 to 20 ppm. Low ash content is important for dielectric properties, such as dielectric strength and dielectric loss. Ash content can be measured according to ISO 3451-1 (1997).

[0021] The melting temperature Tm of the high isotactic homopolymer of propylene may be in the range of 150 to 170°C, preferably 160 to 170°C, as measured according to ISO 11357. The crystallization temperature Tc of the high isotactic homopolymer of propylene may be in the range of 110 to 130°C, preferably 110 to 120°C, as measured according to ISO 11357.

[0022] additives In one embodiment, the polypropylene composition comprises 74.0 to 89.0% by mass, preferably 78.5 to 85.5% by mass, more preferably 80.5 to 85.5% by mass of a high isotactic homopolymer, 10 to 25% by mass, preferably 14 to 21% by mass, more preferably 14 to 19% by mass of a cyclic olefin polymer composition, and 0.0 to 1.0% by mass, preferably 0.0 to 0.5% by mass of additives, where the content of each is again based on the total mass of the polypropylene composition. Preferably, the total content of the high isotactic homopolymer, cyclic olefin polymer composition, and additives is 100% by mass. The additives may be non-polymeric additives and / or polymeric additives. For example, the additives may be selected from the group consisting of antioxidants, stabilizers, acid scavengers, colorants, plasticizers, slip agents, anti-scratch agents, dispersants, processing aids, lubricants, pigments, antistatic agents, etc. Preferably, the additives are selected from the group consisting of antioxidants, stabilizers and acid scavengers. The antioxidant and stabilizer may be selected from the group of hindered phenols, more preferably from the group of hindered phenols that do not contain phosphorus or sulfur.

[0023] The antioxidants and stabilizers are particularly preferably 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene (sold under the trade names Irganox1330, Anox330, Ethanox330 and Kinox-30), pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (sold under the trade names Irganox1010, Anox20, Ethanox310TF and Kinox-10), and octadecyl 3-(3',5'-di-tert-butyl-4-hydroxyphenyl)propionate (Irganox1076, AnoxPP1 It is one or more compounds selected from the group consisting of (sold under the trade names 8 and Kinox-16), butylhydroxytoluene (sold under the trade names IonolCP and VulkanoxBHT), 1,3,5-tris(3',5'-di-tert-butyl-4'-hydroxybenzyl)-isocyanurate (sold under the trade names Irganox3114, AnoxIC-14, Ethanox314 and Kinox-34), and 3,4-dihydro-2,5,7,8-tetramethyl-2-(4,8,12-trimethyltridecyl)-2H-1-benzopyran-6-ol (sold under the trade names IrganoxE210 and α-tocopherol). The antioxidants and stabilizers are preferably present in a total amount of 500 to 8000 ppm relative to the total mass of the polypropylene composition. More preferably, the antioxidants and stabilizers are present in a total amount of 800 to 7000 ppm, even more preferably 1000 to 6000 ppm, and particularly 1500 to 6000 ppm relative to the total mass of the polypropylene composition. Considering the desired applications of the composition in the field of capacitors, the antioxidants and stabilizers are preferably free from phosphorus-containing secondary antioxidants such as tris(2,4-ditert-butylphenyl) phosphite. Although not bound by theory, it is thought that the latter compounds increase dissipation in the final capacitor. The acid scavenger may be a salt of an organic acid such as stearate. These typically help neutralize acids in the polymer. Examples of such compounds include calcium stearate, zinc stearate, and zinc oxide. The acid scavenger is used in an amount of preferably 50 ppm to 2000 ppm, more preferably 50 ppm to 1000 ppm.

[0024] film The present invention further provides a film comprising the above-described polypropylene composition. The film may be a cast film or a biaxially oriented film (BOPP). Furthermore, the film thickness is preferably 1 to 1000 μm, more preferably 1 to 300 μm, most preferably 1 to 250 μm, and particularly 1 to 100 μm. This is particularly advantageous because current attempts are to provide electrical systems with higher energy density and efficiency. Reducing the spatial requirements for the film within the film capacitor contributes to achieving this goal. Preferably, when provided as a cast film with a thickness of 250 μm, the dielectric breakdown voltage of the film is 118 kV / mm or higher, preferably 125 kV / mm or higher, when measured at 90°C according to IEC 60243-1. For example, a cast film with a thickness of 250 μm measured at 90°C according to IEC 60243-1 may have a dielectric breakdown voltage in the range of 118 to 250 kV / mm, preferably 125 to 200 kV / mm. When the cast film is provided with a thickness of 250 μm, the loss loss tangent is preferably less than 0.001, more preferably less than 0.0005, and even more preferably less than 0.0002, when measured at 20 Hz and 120°C. For example, the loss loss tangent of the cast film is in the range of 0.00001 to 0.001, preferably 0.00001 to 0.0005, and more preferably 0.00005 to 0.0002, when measured at 20 Hz. The conductivity of the cast film according to the present invention may be 2 fS / cm or less. For example, the conductivity of the cast film may be 0.01 to 2 fS / cm. The conductivity is measured at a temperature of 90°C and a film thickness of 250 μm, respectively, and is 10 -2 ~10 -1 It may be taken as the reciprocal of the DC electrical resistance measured according to IEC62631-3-2 using AC in the frequency range of Hz, or according to ASTM D257.

[0025] The biaxially oriented polypropylene film of the present invention can be obtained in two steps. In the first step, a non-oriented film is produced by extruding a polypropylene composition through a flat die. In the second step, the non-oriented film is stretched in the machine direction (MD) and the transverse direction (TD). The stretching or orientation of the non-oriented film may be performed simultaneously in the longitudinal and transverse directions. The two steps of this method may preferably be carried out in a continuous process. Alternatively, the non-oriented film may be recovered, cooled and solidified on a rotating cooling roll, and then stretched. In one embodiment, the biaxially oriented polypropylene film contains at least 80% by mass of the polypropylene composition defined in the present invention, more preferably at least 90% by mass, and even more preferably consists of the same. The stretch ratio of the biaxially oriented polypropylene film is preferably at least 4 times in the longitudinal direction, preferably at least 5 times, at least 4 times in the transverse direction, preferably at least 5 times, and more preferably at least 9 times in the longitudinal direction and at least 5 times in the transverse direction. Biaxially oriented polypropylene films can be prepared by conventional stretching processes known in the art. Therefore, a method for producing biaxially oriented polypropylene films can preferably utilize the tenter method known in the art. The tenter method is a method for obtaining a non-oriented film by melt-extruding the polypropylene composition of the present invention from a slit die such as a T-die and cooling it on a cooling drum. The film is preheated, for example, on heated metal rolls, then stretched longitudinally between a plurality of rolls with established peripheral speed differences, and then both edges are gripped by grippers, and the sheet is stretched transversely in an oven by a tenter to obtain a biaxially oriented film. The temperature of the film during longitudinal stretching is preferably controlled to be within the melting point temperature range of the polypropylene composition. Subsequently, the biaxially oriented film may be treated by corona discharge in air, nitrogen, carbon dioxide gas, or a mixture thereof. If the film is to be metallized for film capacitor applications, this increases the adhesive strength to the deposited metal.

[0026] Capacitor In other embodiments, the present invention relates to a capacitor comprising the biaxially oriented film described above. This capacitor comprising the biaxially oriented film is expected to have a longer lifespan and higher temperature resistance than conventional capacitors. Preferably, the biaxially oriented film is metallized, and the capacitor is a metallized film capacitor. The metallization of the biaxially oriented film can be carried out by any method known in the art, for example, evaporation, electrodeposition, melting, ion beam vacuum deposition, sputtering, or ion plating. The thickness of the resulting metal layer may be 100 angstroms (0.01 μm) to 5000 angstroms (0.5 μm). Embodiments of the present invention are illustrative and are not limited to those shown in the accompanying drawings, where the same reference numerals represent similar elements. [Brief explanation of the drawing]

[0027] [Figure 1] This graph shows the results of dielectric spectroscopy measurements performed using the materials described in the examples. [Figure 2] This graph shows the results of dielectric spectroscopy measurements performed using the materials described in the examples. [Figure 3] This graph shows that the electrical breakdown behavior of several exemplary materials can be compared. [Figure 4] (a) to (d) are atomic force microscope images of several exemplary materials. [Modes for carrying out the invention]

[0028] Measurement method Quantification of fine structure by NMR spectroscopy The isotacticity and comonomer content of the polymer were quantified using quantitative nuclear magnetic resonance (NMR) spectroscopy. quantitative 13 C{ 1 The H}NMR spectrum is, 1 H and 13 For C, the spectra were recorded in solution using a Bruker Advance III 400 NMR spectrometer operated at 400.15 MHz and 100.62 MHz, respectively. All spectra were recorded at 125°C using nitrogen gas at all air pressures. 13 The temperature was recorded using a C-optimized 10mm extended temperature probe head. For polypropylene homopolymers, approximately 200 mg of the material was dissolved in 1,2-tetrachloroethane-d2 (TCE-d2). After the initial sample preparation in a heat block, the NMR tube was further heated in a rotating oven for at least 1 hour to ensure a homogeneous solution. After insertion into a magnet, the tube was rotated at 10 Hz. This setting was chosen primarily for the high resolution required for the quantification of stereoregularity distribution (Busico, V., Cipullo, R., Prog. Polym. Sci. 26 (2001) 443 and Busico, V.; Cipullo, R., Monaco, G., Vacatello, M., Segre, AL, Macromoleucles 30 (1997) 6251). Using a standard single-pulse excitation with NOE and a bilayer Waltz 16 decoupling scheme (Zhou, Z., Kuemmerle, R., Qiu, X., Redwine, D., Cong, R., Taha, A., Baugh, D. Winniford, B., J. Mag. Reson. 187 (2007) 225; Busico, V., Carbonniere, P., Cipullo, R., Pellecchia, R., Severn, J., Talarico, G., Macromol. Rapid Commun. 2007, 28, 11289), a total of 8192 transient events per spectrum (8k) were obtained. quantitative 13 C{ 1 The 1H NMR spectrum was processed and integrated, and the relevant quantitative characteristics were determined from the integral using a proprietary computer program. In polypropylene homopolymers, all chemical shifts are methyl isotactic pentads at 21.85 ppm. <mmmm>This will be used as the internal standard. Characteristic signals corresponding to regio defects (Resconi, L., Cavallo, L., Fait, A., Piemontesi, F., Chem. Rev. 2000, 100, 1253; Wang, WJ., Zhu, S., Macromolecules 33 (2000), 1157; Cheng, HN, Macromolecules 17 (1984), 1950) or comonomers were observed. The stereoregularity distribution was quantified by integrating the methyl region between 23.6 and 19.7 ppm, and corrected for any sites unrelated to the desired stereosequence (Busico, V., Cipullo, R., Prog. Polym. Sci. 26 (2001) 443; Busico, V., Cipullo, R., Monaco, G., Vacatello, M., Segre, AL, Macromoleucles 30 (1997) 6251). Specifically, the influence of regio defects and comonomers on the quantification of stereoregularity distribution was corrected by subtracting representative regio defect and comonomer integrals from a specific integral region of the stereoarrangement. Isotacticity is determined at the pentad level, and the percentage of isotactic pentad (mmmm) sequences relative to all pentad sequences is: [mmmm]% = 100 × (mmmm / total pentads) This was reported. If necessary, the absence of ethylene in high-isotactic propylene homopolymers was obtained using the method of Wang et al. (Wang, WJ., Zhu, S., Macromolecules 33 (2000), 1157) under specified conditions. 13 C{ 1 Quantification can be achieved by integrating multiple signals across the entire spectral range of the H} spectrum. This method was chosen for its accuracy, robustness, and ability to account for the presence of regio defects when necessary. By slightly adjusting the integration region, it can be applied to a wider range of comonomer content. The molar ratio of ethylene uptake is as follows: E [mol%] = 100 × fE It is calculated as follows. The mass percentage of ethylene uptake is as follows: E[mass%]=100×(fE×28.05) / ((fE*28.05)+((1-fE)×42.08)) It is calculated as follows. MFR 2 MFR2 was measured according to ISO 1133 (2.16 kg load) at a temperature of either 230°C (for high isotactic homopolymers of propylene) or 260°C (for cyclic olefin copolymer compositions). Glass transition temperature Tg The glass transition temperature was measured using a differential scanning calorimeter at a scanning speed of 10 K / min, in accordance with ISO 11357. Melting point Tm, crystallization temperature Tc Differential scanning calorimetry (DSC) experiments were performed using a TA Instruments Q2000 instrument calibrated with indium, zinc, and tin according to ISO 11357 / 1. Measurements were performed in accordance with ISO 11357 / 3, at a scanning speed of 10 K / min between -30°C and 225°C, using a heating / cooling / heating cycle with a sample of 5 ± 0.5 mg under a nitrogen atmosphere (50 mL / min). The melting point (Tm) and crystallization temperature (Tc) were obtained as the endothermic and exothermic peaks in the cooling cycle and the second heating cycle, respectively.

[0029] ash The ash content of the polymer was measured according to ISO 3451-1 (1997). Approximately 100 g of polymer was weighed into a platinum crucible. The crucible was then heated in a Bunsen burner flame to slowly burn the polymer. After complete combustion of the polymer, the crucible was cooled, dried, and weighed. The ash content was calculated by dividing the mass of the residue by the mass of the polymer sample. At least two measurements were performed, and if the difference in measurements exceeded 7 ppm, a third measurement was performed.

[0030] Dielectric breakdown measurement Dielectric breakdown strength is synonymous with the breakdown field, is generally expressed in kV / mm, and is a characteristic of gases, liquids, and solids. When the electric field exceeds the breakdown field, breakdown occurs through a discharge channel in the material, and the electrodes connect. In solids, the material is irreversibly destroyed by the discharge, but in gases and liquids, the damage is temporary and reversible. Generally, dielectric breakdown events occur with high randomness; that is, when testing the same sample to establish a dielectric breakdown distribution (see details below), high data variance is observed, and the data often does not follow a normal distribution (see Dissado LA; Fothergill JC "Electrical degradation and breakdown in polymers", IEEE Materials and Devices Series 9, Peter Peregrinus Ltd., 1992). The reason why dielectric breakdown events occur randomly is the nonspecific and localized onset of dielectric breakdown in areas of increased electric field and areas of low dielectric breakdown strength (see above). In general, structural heterogeneity of materials, the inclusion of contaminants or voids (see Chen G.; Davies AE. The influence of defects on the short-term breakdown characteristics and long-term DC performance of LDPE insulation. IEEE Transactions on Electrical Insulation, 2000, 7, 401-407), and surface roughness (Rytoluoto L; Gitsas A.; Pasanan S.; Lahti K. Effect of film structure and morphology on the dielectric breakdown characteristics of cast and biaxially oriented polypropylene films. European Polymer Journal, 2017, 95, 606-624) can be potential failure sites, and these are unavoidable in industrial production.

[0031] Dielectric breakdown test The breakdown strength of the solid was tested using a short-voltage ramp test. A thin test specimen (250 μm thick) of cast film was placed between electrodes at a temperature of 90°C, and the voltage was increased (linearly, exponentially, stepwise, etc.) until dielectric breakdown occurred. The voltage at which dielectric breakdown occurs is the dielectric breakdown voltage (kV) of the test specimen (see IEC 60234-1 (2013) - Electric strength of insulating materials - Test methods - Part 1 : Tests at power frequencies). Subsequently, the sample thickness at the fracture point was measured to obtain the fracture strength Eb (kV / mm). This test was repeated on similarly prepared specimens of the material to obtain the fracture distribution of the material (see Rytoluoto T; Gitsas A.; Pasanan S.; Lahti K. Effect of film structure and morphology on the dielectric breakdown characteristics of cast and biaxially oriented polypropylene films. European Polymer Journal, 2017, 95, 606-624).

[0032] Statistical evaluation The breakdown distribution obtained from voltage ramp tests typically does not follow a normal distribution, but rather follows an extreme value distribution for which the Weibull distribution is commonly used (see Dissado LA; Fothergill JC "Electrical degradation and breakdown in polymers", IEEE Materials and Devices Series 9, Peter Peregrinus Ltd., 1992, and IEC 62539 (2007) - Guide for the statistical analysis of electrical insulation breakdown data). The Weibull distribution uses three parameters, as originally proposed: a scale parameter a, a shape parameter b, and a position parameter b. The scale parameter a is the mean of the Weibull distribution and is used similarly to the mean of a normal distribution, but they are not equivalent. The mean is the 50th percentile of the normal distribution, while the scale parameter a is the 63.2nd percentile of the Weibull distribution. When referring to the fracture strength of a material, many authors essentially refer to the scale parameter a. The shape parameter b, as its name suggests, affects the shape of the Weibull distribution; a low b makes it look like an exponential distribution, while a high b makes it look almost bell-shaped, like a normal distribution. Thus, a high b implies low variance and a bell shape. The position parameter d is a "shift constant" because it shifts the experimental distribution to the origin, i.e., when Eb-d=0 the failure probability is zero. However, d is often not needed and is assumed to be zero, and the authors apply the Weibull distribution using only two parameters, a and b.

[0033] Measurement details The measured fracture strength and fracture distribution are affected by experimental details such as the use of DC or AC current (Krentz T.; Khani MM; Bell M.; Benicewicz BC; Nelson JK; Zhao S.; Schadler LS Morphologically dependent alternating-current and direct-current breakdown strength in silica-polypropylene nanocomposites. Journal of Applied Polymer Science, 2017, 134) and voltage ramp rate (Rytoluoto L; Ritamaki M.; Lahti K.; Karttunen M. Ramp rate effect on the breakdown response of SiCk-BOPP Nano composites, IEEE International conference on the properties of applications of dielectric materials, 2015, 496-499). One further important experimental detail is the measured volume.The thickness and (electrode) area of ​​the sample affect the dielectric breakdown strength (see Laihonen SJ et al. "Area dependence of breakdown strength of polymer films: automatic measurement method." IEEE Transactions on dielectrics and electrical insulation, 2007, 14, 263-274, and Rytoluoto L; Lahti K. Effect of film thickness and electrode area on the dielectric breakdown characteristics of metallized film capacitor films, 23rd Nordic Insulation Symposium (Nordis 13), 2013, 33-38), and must be reported along with the breakdown results. The geometric shape of the electrode, including its shape and size, is relevant to the volume effect on fracture strength. Common electrode shapes include parallel plates, cylindrical plates, and spherical plates. In the latter case, the active electrode area is the contact area between the sphere and the sample, so the stressed active area of ​​the sample is much smaller than the electrode diameter. Furthermore, dielectric breakdown can occur through the air gap between the electrode and the film outside the contact area, potentially affecting the dielectric breakdown statistics.

[0034] Following electrode design, data acquisition techniques play a role in determining how many samples are tested to establish the fracture distribution. Generally, the more samples tested, the more extreme results are found; that is, more very low and very high Eb values ​​are measured, affecting the fracture distribution. In the common voltage ramp test described above, samples are fractured individually and then subsequently. Each new sample is exposed to a new voltage ramp starting from zero voltage, and fracture always occurs at the weakest spot in the sample, stopping the voltage ramp. Even if there are stronger spots in the sample, they are not measured; in other words, the strongest part of the sample, usually the strongest part of the material, is not tested. While testing more samples may include results with higher fracture intensities in the distribution, this individual sample method biases the fracture intensity distribution towards lower fracture intensities. Automated dielectric breakdown measurement methods have advanced (Boggs SA; Ho J.; Jo TR; Overview of Laminar Dielectric Capacitors, Electrical Insulation Magazine, 2010, 26, 7-13, and Rytoluoto L; Lahti K. New approach to evaluate area-dependent breakdown characteristics of dielectric polymer films, Transactions on Dielectrics and Electrical Insulation, 2013, 20, 937-946, and Kerwien CM; Malandro DL; Broomall JR, Large area DC dielectric breakdown voltage measurement of BOPP and PTFE thin films, IEEE Conference on Insulation and Dielectric Phenomena, 2016, 486-489, and Laihonen SJ et al. "Area dependence of breakdown strength of polymer films: automatic measurement method." IEEE Transactions on dielectrics and electrical insulation, 2007, 14). (See 263-274), one subtype measures all individual dielectric breakdowns, i.e., the complete dielectric breakdown distribution, at a single voltage ramp (multiple dielectric breakdowns) on the same sample (region) (Boggs SA; Ho J.; Jo TR; Overview of Laminar Dielectric Capacitors, Electrical Insulation Magazine, 2010, 26, 7-13 and Rytoluoto L; Lahti K.).A new approach to evaluate area-dependent breakdown characteristics of dielectric polymer films (Transactions on Dielectrics and Electrical Insulation, 2013, 20, 937-946). In this method, after the weaker portion of the sample is destroyed, the stronger portion of the sample is destroyed as the voltage continues to increase. As a result, the dielectric breakdown distribution obtained by this test typically contains very high dielectric breakdown intensities; therefore, this method biases the dielectric breakdown distribution to higher dielectric breakdown intensities than manual individual methods. In short, when reporting destructive data, direct comparisons can be made between materials using the same test method, area, voltage ramp rate, and statistical evaluation, but comparisons cannot be made between different tests.

[0035] conductivity Conductivity was calculated as the reciprocal of electrical resistance, determined according to ASTM D257. Dielectric Analysis (DEA) Dielectric analysis (DEA) is performed using a TA-Instruments DEA 2070 equipped with gold-plated sputtering. Measurements are taken at 50 Hz with a gradient of 3°C / min up to 130°C, under a constant spring force (F) of 100 N. Dielectric analysis measures two fundamental electrical properties of a material: capacitance and conductivity, as functions of time, temperature, and frequency. Capacitance is the ability of a material to store electric charge, while conductivity is its ability to conduct electric charge. Capacitance and conductivity are important properties. Dissipation is independent of the film thickness or orientation angle. The properties measured by dielectric analysis are as follows: e' = real part of dielectric constant ε'' = imaginary part of the dielectric constant (loss rate) tanδ=loss tangent (e'' / e') σ = Ionic conductivity [1 / Ωcm] Electrical conductivity is proportional to the dielectric constant, and ionic conductivity is derived from the loss rate. Both the dielectric constant and the loss rate provide valuable information about molecular motion. The dielectric constant determines the alignment of dipoles, and the loss rate corresponds to the energy required to align the dipoles and move the ions. Since dipoles cannot move to align themselves by an electric field, the dielectric constant is low for polymers at low temperatures. Ionic conductivity is not important until the polymer becomes a fluid, i.e., beyond the glass transition temperature (Tg) and melting temperature (Tm). If the temperature is higher than the glass transition temperature, the following formula can be used with respect to the loss rate:

[0036] [ka] (In the formula, σ = ionic conductivity) ω=angular frequency (2πf) f=frequency (Hz) e0 = absolute permittivity of free space (8.85 × 10⁻⁶) -12 F / m)) The bulk ion conductivity is calculated using [this method].

[0037] Dielectric spectroscopy Dielectric spectroscopy measurements were performed on the film using a Novocontrol Alpha frequency analyzer at a temperature of 120°C and atmospheric pressure. The frequency range for DS measurements was 10 -2 ~10 6 The value was Hz. A piece of film, cut to an appropriate size, was placed between two identical electrodes with a diameter of 40 mm. The measurement was performed under a nitrogen atmosphere.

[0038] Atomic force microscope image All samples were taken directly from the film sample, and the film core was cut perpendicular to the mechanical direction (MD) using a cryogenic microtome. No surface treatment was performed. In addition to "conventional" scanning, qualitative amplitude-frequency modulation (AM-FM) was performed because this approach allows for better distinction of different phases. 20 × 20 μm of film. 2 The comparison was based on a single image with a large surface area.

[0039] material The example materials were prepared using the polymers listed in Table 1 below. Table 1: Polymers used in the production of CE1, CE2, and IE1-IE3

[0040] [Table 1] The above polymers were combined in the amounts shown in Table 2 below and melt-blended to form Example Materials CE1, CE2, and IE1-IE3. Example Materials CE2 and IE1-IE3 are polypropylene compositions containing predetermined amounts of cyclic olefin polymers. Example Material CE1 is a pure, high-isotactic homopolymer of polypropylene.

[0041] Table 2: Composition of sample materials CE1, CE2, and IE1-IE3

[0042] [Table 2] Film samples were manufactured from sample material using a small laboratory blow-molded film line manufactured by COLLIN Lab&Pilot Solutions GmbH. This line consists of an extruder with a φ30 mm screw and an L / D ratio of 30. The extruder temperature was set to 235°C and recorded after 45 minutes of process stabilization at the melting temperature of 235°C. Following the extruder was a 300 mm wide die. The die has a flexible die lip with a die gap of 0.5–1.5 mm. The line was operated at a constant throughput of 8 kg / h and a line speed of 10 m / min. The film was cut to a width of 270 mm. The film was manufactured with a thickness of 250 μm. Subsequently, the conductivity of films CE1, CE2, and IE1-IE3 was measured at varying frequencies. The frequency dependence can be derived from Figure 1. It was found that the conductivity of propylene compositions containing cyclic olefin polymers such as CE2 and IE1-IE3 was lower than that of pure high-isotactic homopolymer polypropylene CE1 across the entire measured frequency range. For push-pull capacitors, the IE2 is most effective at the low-frequency end of approximately 10⁻² to 10⁻¹ Hz, which is particularly important. The energy dissipation capability at different frequencies is evaluated based on the loss tangent tanδ. Therefore, the imaginary part ε' and the real part ε'' of the dielectric constant were measured, and tanδ was calculated as the ratio ε' / ε''. A plot of tanδ against frequency can be seen in Figure 2. Generally, a lower tanδ value is expected to indicate better energy storage performance and a lower risk of damage due to localized temperature increases. Thus, propylene composition IE2 performs particularly well over other compositions and pure, high-isotactic polymers of low-frequency propylene, yielding the best score. Figure 3 is a bar graph that allows us to draw conclusions regarding the fracture durability of films made from CE1, CE2, and IE1. It can be seen that the breakdown voltage of IE1 was approximately 10% higher than that of CE1 and CE2. The morphology of films fabricated from CE2 and IE1-IE3 was examined using atomic force microscopy. From the AFM images in Figures 4(a)-(d), it can be concluded that the dispersion quality of the compositions in Figures 4(b)-(d) corresponding to IE1-IE3 is far better than that of the composition in Figure 4(a) corresponding to CE2. Although not theoretically bound, this is considered an indicator of higher homogeneity of IE1-IE3 and improved overall macroscopic dielectric performance.< / mmmm> < / mmmm>

Claims

1. A polypropylene composition, A high isotactic homopolymer (A) of propylene in an amount of 70 to 95% by mass of the total mass of the polypropylene composition, and A cyclic olefin polymer composition (B) comprising 5 to 30% by mass of the total mass of the polypropylene composition, and having a glass transition temperature measured according to ISO 11357 in the range of 140 to 155°C. This includes, and here, The cyclic olefin polymer composition (B) comprises at least a first cyclic olefin polymer (b1) and a second cyclic olefin polymer (b2), A polypropylene composition in which the glass transition temperature of the first cyclic olefin polymer (b1) is less than 140°C, as measured according to ISO 11357.

2. The polypropylene composition according to claim 1, wherein the glass transition temperature of the cyclic olefin polymer composition (B) is in the range of 140 to 150°C, 140 to 144°C, 140 to 143°C, or 145 to 155°C.

3. The MFR of the cyclic olefin polymer composition (B) as measured according to ISO 1133 ２ The polypropylene composition according to claim 1 or 2, wherein the (260°C) concentration is 2 to 50 g / 10 min or 8 to 25 g / 10 min.

4. The cyclic olefin polymer composition (B) is such that, with respect to the total mass of the cyclic olefin polymer composition (B), 70-90% by mass, 75-85% by mass, or 75-80% by mass of cyclic olefin units, such as norbornene units, and It contains acyclic olefin units, such as ethylene units, in an amount of 10-30% by mass, 15-25% by mass, or 20-25% by mass. The polypropylene composition according to any one of claims 1 to 3.

5. With respect to the total mass of the polypropylene composition, A high isotactic homopolymer (A) of propylene in an amount of 75-90% by mass, 79-86% by mass, or 81-86% by mass, and A cyclic olefin polymer composition (B) comprising 10-25% by mass, 14-21% by mass, or 14-19% by mass, A polypropylene composition according to any one of claims 1 to 4.

6. The polypropylene composition according to any one of claims 1 to 5, wherein the cyclic olefin polymer composition (B) comprises or consists of at least one cyclic olefin copolymer selected from the group consisting of at least one cyclic olefin copolymer, norbornene-ethylene copolymer, and tetracyclododecene-ethylene copolymer, or a blend of at least two of the cyclic olefin copolymers.

7. The polypropylene composition according to any one of claims 1 to 6, wherein the glass transition temperature of the first cyclic olefin polymer (b1) is 60°C to less than 140°C when measured according to ISO 11357, and / or the glass transition temperature of the second cyclic olefin polymer (b2) is at least 155°C, particularly at least 155 to 190°C when measured according to ISO 11357.

8. The high isotactic homopolymer of propylene (A) is as follows: - １３ The isotactic pentad content in the fraction measured by 13C NMR is 93–99.5%, 95–99.0%, or 96–98.5%; MFR measured according to ISO 1133 ２ (230°C) is 0.4–10 g / 10 min or 0.5–5 g / 10 min; The ash content, as measured according to ISO 3451-1 (1997), is 60 ppm or less or 30 ppm or less; and The crystallization temperature (Tc), as measured according to ISO 11357, is 110–130°C, 110–120°C, or 250–250°C; At least one of the following: The polypropylene composition according to any one of claims 1 to 7.

9. The polypropylene composition according to any one of claims 1 to 8, obtained by melt-blending a high isotactic homopolymer of propylene (A) and the cyclic olefin polymer composition (B), wherein, in some cases, the cyclic olefin polymer composition (B) itself is obtained by melt-blending at least two different cyclic olefin polymers.

10. A cast film comprising the polypropylene composition according to any one of claims 1 to 9.

11. The cast film according to claim 10, wherein the dielectric breakdown voltage is 118 kV / mm or more or 125 kV / mm or more, and the dielectric breakdown voltage is measured on a cast film with a thickness of 250 μm at 90°C in accordance with IEC 60243-1.

12. The cast film according to claim 10 or 11, wherein the loss tangent is less than 0.001, less than 0.0005, or less than 0.0002, wherein the loss tangent is measured at 20 Hz and 120°C according to the method herein.

13. According to IEC 62631-3-2, 10 －２ ~10 －１ A cast film according to any one of claims 10 to 12, wherein the conductivity on a cast film with a thickness of 250 μm at a temperature of 90°C is 2 fS / cm or less, when measured using an AC current in the frequency range of Hz, or when taken as the reciprocal of the DC electrical resistance measured according to ASTM D257.

14. A biaxially oriented film comprising the polypropylene composition according to any one of claims 1 to 9.

15. A capacitor comprising a biaxially oriented film as described in claim 14.

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