A composition comprising polypropylene and cyclic olefin polymers with improved dispersion properties and fracture performance.

Abstract

The present invention relates to a polypropylene composition comprising 83 to 87% by mass of a propylene homopolymer (A) and 13 to 17% by mass of a cyclic olefin polymer (B) containing cyclic olefin units, wherein the content of the cyclic olefin units is in the range of 82 to 86% by mass relative to the total mass of the cyclic olefin polymer. The present invention further relates to a film comprising the above composition, which may be a cast film or a biaxially oriented film. 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 83 to 87% by mass of a propylene homopolymer (A) and 13 to 17% by mass of a cyclic olefin polymer (B) containing cyclic olefin units, wherein the content of the cyclic olefin units is in the range of 82 to 86% by mass relative to the total mass of the cyclic olefin polymer. The present invention further relates to a film comprising the above composition, which may be a cast film or a biaxially oriented film. The present invention also provides a capacitor comprising the biaxially oriented film. [Background technology]

[0002] Polypropylene has a relatively high dielectric constant, low dielectric loss tangent, and good dielectric strength. For these reasons, polypropylene has been conveniently used as a dielectric in various capacitor film applications. However, a problem with conventional polypropylene capacitor grades is their limited maximum operating temperature. New generations of inverters, such as traction inverters for electric mobility and inverters for renewable power sources like solar and wind, require higher temperature tolerance for 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 when the beta nucleation of high-purity polypropylene is combined with long-chain branched polypropylene, high-temperature resistance can be achieved. More specifically, the present invention provides a polypropylene composition comprising a propylene homopolymer of 95.0 to 99.9% by mass, a long-chain branched polypropylene of 0.1 to 5.0% by mass, and a beta nucleating agent up to 1000 ppm, which has a specific melt flow rate and an extremely low ash content. Patent Documents 3 and 4 suggest that in order to obtain a material suitable for high-temperature capacitor applications, it may be preferable to blend polypropylene with a specific amount of a specific cyclic olefin copolymer. In this regard, Patent Document 3 depends 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, in the above approach, in order to enhance the temperature resistance of the capacitor polypropylene composition, other important properties have to be sacrificed. For example, mechanical properties such as low shrinkage and high rigidity, as well as the resistance performance to high voltage, are sacrificed to some extent.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Summary of the Invention

Problems to be Solved by the Invention

[0004] Therefore, there is still a need to improve and set the properties for capacitor applications, that is, to provide a polypropylene composition having 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 provide a corresponding polypropylene composition. Another object of the present invention is to provide a polypropylene film having excellent performance for capacitor applications. Finally, the present invention aims to improve the specifications of capacitors. Furthermore, the capacitor film needs to have high dielectric breakdown strength and good mechanical properties such as low shrinkage and high rigidity.

Means for Solving the Problems

[0005] The above object is solved by a polypropylene composition having the features of independent claim 1, a film having the features of claim 9, and a capacitor having the features of claim 12. The polypropylene composition according to the present invention is as follows: based on the total mass of the polypropylene composition 83 to 87% by mass of propylene homopolymer (A), and 13 to 17% by mass of cyclic olefin polymer (B) containing cyclic olefin units and non-cyclic olefin units, where the content of the cyclic olefin units is in the range of 82 to 86% by mass based on the total mass of the cyclic olefin polymer (B). The content of the cyclic olefin polymer (B) can be determined by measuring the xylene-soluble content of the polypropylene composition. When the cyclic olefin polymer (B) is soluble, the content of the cyclic olefin units of the cyclic olefin polymer (B) is 13The content can be determined by 13C NMR spectroscopy, and if the cyclic olefin polymer (B) is insoluble, it can be calculated from the glass transition temperature of the cyclic olefin polymer. If the cyclic olefin polymer (B) is norbornene ethylene copolymer and the cyclic olefin units are norbornene units, refer to Macromol. Chem. Phys. 199, 1221-1232 (1998) for its content.

[0006] Since the polypropylene composition contains 83 to 87% by mass of polypropylene homopolymer (A) relative to the total mass of the composition, the amount of the remaining components is sufficiently high to achieve the desired properties. Preferably, the polypropylene composition contains 83.5 to 86.5% by mass, more preferably 84.0 to 86.0% by mass, and especially about 85.0% by mass of polypropylene homopolymer (A) relative to the total mass of the composition. On the other hand, the polypropylene composition contains 13.5 to 16.5% by mass, more preferably 14.0 to 16.0% by mass, and especially about 15.0% by mass of cyclic olefin polymer (B) relative to the total mass of the composition.

[0007] In one embodiment, the polypropylene composition further comprises additives. The polypropylene composition may contain 82 to 86% by mass of a propylene homopolymer (A) relative to the total mass of the polypropylene composition, 12 to 16% by mass of a cyclic olefin polymer (B) containing cyclic olefin units and acyclic olefin units relative to the total mass of the polypropylene composition, and 0 to 2% by mass of additives, wherein the content of cyclic olefin units is in the range of 82 to 86% by mass relative to the total mass of the cyclic olefin polymer (B). In a preferred embodiment, the polypropylene composition is obtained by melt-blending a polypropylene homopolymer (A) and a cyclic olefin polymer (B). The apparatus capable of performing the melt-blending can be selected from the group consisting of kneaders, mills, and extruders. In contrast to the dry blending method, the melt blending method can produce a uniform polypropylene composition. The cyclic olefin polymer (B) is finely and uniformly dispersed in the matrix of the polypropylene homopolymer (A). Generally, the dispersion state of the cyclic olefin polymer is thought to affect the mechanical and electrical properties of the propylene composition. In particular, insufficient dispersion may lead to localized stresses that cause defects during the stretching of the film containing the polypropylene composition. Furthermore, insufficient dispersion of the cyclic olefin polymer makes the film containing the polypropylene composition more susceptible to dielectric breakdown. The dimensions and shapes of domains formed by the cyclic olefin polymer (B) in the dispersion can be analyzed using an atomic force microscope (AFM) or another type of microscope. Considering the above, when a 250 μm thick unoriented cast film made of a polypropylene composition is analyzed by AFM, preferably more than 50% (d50), particularly more than 90% (d90), for example 95% (d95), of the domains of the cyclic olefin polymer (B) have a maximum dimension smaller than 2.0 μm.

[0008] Polypropylene homopolymer (A) The term "polypropylene 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, only propylene units are used, as described in the Examples section below. 13 It can be detected in polypropylene homopolymers by 13C NMR spectroscopy. Preferably, the polypropylene homopolymer is linear polypropylene, i.e., polypropylene without detectable amounts of long-chain or short-chain branching. Furthermore, the melt flow rate (MFR) of the propylene homopolymer (A) used in the composition of the present invention is preferably within a specific range. The melt flow rate measured at 230°C under a load of 2.16 kg according to ISO 1133 is shown as MFR2(230°C). For polypropylene homopolymer (A), the MFR2(230°C) measured according to ISO 1133 is preferably 1.0 to 10 g / 10 min, preferably 1.0 to 7.0 g / 10 min, and more preferably 1.0 to 5.0 g / 10 min. One important aspect of polypropylene compositions for capacitor film applications is their high purity. This is particularly desirable because low ash content negatively affects dielectric properties. Therefore, it is understood that the ash content of polypropylene homopolymer (A) should be low. Preferably, the ash content of propylene homopolymer (A), as measured according to ISO 3451-1 (1997), is 60 ppm or less, more preferably 50 ppm or less, more preferably 40 ppm or less, more preferably 30 ppm or less, for example, in the range of 10 to 30 ppm. Furthermore, the ash content of the polypropylene composition as a whole is generally quite low, and it is understood that the ash content, as measured according to ISO 3451-1 (1997), is 60 ppm or less, more preferably 50 ppm or less, more preferably 40 ppm or less, more preferably 30 ppm or less, for example, in the range of 10 to 30 ppm. Typically, 1 ppm of any component, such as ash, corresponds to 1 mg of that component in 1 kg of the polypropylene composition. In a preferred embodiment of the present invention, the polypropylene homopolymer (A) is a high-isotactic polypropylene. 13 It is more preferable that the material is a high-isotactic polypropylene having an isotactic pentad fraction content of 93-99.5%, preferably 95-99.0%, and more preferably 96-98.5%, as measured by 13C NMR spectroscopy.

[0009] Furthermore, polypropylene compositions designed for capacitor applications are ideally characterized by a fairly low content of low-temperature xylene-soluble components (XCS). Therefore, in a more preferred embodiment of the present invention, the XCS content of the polypropylene homopolymer (A) of the present invention is 0.1 to 4.0% by mass, preferably 0.3 to 2.0% by mass, as measured by ISO 16152. It is particularly understood that the polypropylene homopolymer (A) may be characterized by an XCS content of less than 2.0% by mass, more preferably 1.8% by mass or less, and even more preferably 1.6% by mass or less, as measured by ISO 16152. The propylene homopolymer (A) is even more preferable if its crystallization temperature is within a specific range, as this improves the processability of the polypropylene composition. In a preferred embodiment of the present invention, the glass transition temperature Tc of the propylene homopolymer (A), measured according to ISO 11357, i.e., by differential scanning calorimetry (DSC) at a scanning speed of 10 K / min, is 110 to 130°C, preferably 110 to 120°C.

[0010] Cyclic olefin polymer (B) The cyclic olefin polymer is preferably a thermoplastic polymer. The term "cyclic olefin polymer" is understood to refer to a polymer containing cyclic olefin units. A cyclic olefin polymer may be a cyclic olefin homopolymer or a cyclic olefin copolymer.

[0011] 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 that 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.

[0012] 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):

[0013] [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):

[0014] [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].

[0015] 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. In one embodiment, the cyclic olefin polymer is a cyclic olefin copolymer selected from the group consisting of norbornene ethylene copolymer and tetracyclododecene ethylene copolymer. Non-limiting examples of cyclic olefin polymers include polymers commercially available as APEL® from Mitsui Chemicals or TOPAS® from TOPAS Advanced Polymers.

[0016] 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. Furthermore, if the cyclic olefin polymer is a 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 copolymer can raise the glass transition temperature. The same applies to other combinations of cyclic olefin monomers and acyclic olefin monomers. Accordingly, it is understood that the cyclic olefin units in the cyclic olefin polymer (B) are preferably selected from the group consisting of cyclopentadiene units, norbornene units, tetracyclododecene units and their derivatives, and the acyclic olefin units in the cyclic olefin polymer (B) are preferably selected from linear C2-C8α olefin units. In this regard, the polypropylene composition according to the present invention may be defined as a composition comprising 83-87% by mass of a propylene homopolymer (A) based on the total mass of the polypropylene composition, and 3-17% by mass of a cyclic olefin polymer (B) containing norbornene units and ethylene units based on the total mass of the polypropylene composition. In the reference embodiment, the norbornene unit content is in the range of 73-77% by mass based on the total mass of the cyclic olefin polymer (B). In one embodiment of the present invention, the norbornene unit content is in the range of 82-86% by mass based on the total mass of the cyclic olefin polymer (B). In the reference embodiment, when the content of cyclic olefin units such as norbornene units relative to the total mass of the cyclic olefin polymer (B) is in the range of 73 to 77% by mass, the content of cyclic olefin units such as norbornene units relative to the total mass of the cyclic olefin polymer (B) is preferably 73.5 to 76.5% by mass, more preferably 74.0 to 76.0% by mass, and particularly about 75.0% by mass. Furthermore, in this case, the content of acyclic olefin units, such as α-olefin units such as ethylene units, is preferably 23.5 to 26.5% by mass, more preferably 24.0 to 26.0% by mass, and particularly about 25.0% by mass, relative to the total mass of the cyclic olefin polymer (B). In the reference form, when the content of cyclic olefin units such as norbornene units is in the range of 73 to 77% by mass, the corresponding cyclic olefin polymer (B) is: The glass transition temperature (Tg) measured according to ISO 11357 is in the range of 125 to 145°C, more preferably in the range of 130 to 140°C, even more preferably in the range of 132 to 138°C, particularly about 134°C; and / or The melt flow rate MFR2 (260°C / 2.16 kg), as measured according to ISO 1133, is in the range of 40-55 g / 10 min, more preferably 45-50 g / 10 min, and particularly about 48 g / 10 min. When the cyclic olefin polymer contains cyclic olefin units such as norbornene units in the above-mentioned content, and one or both of the above-mentioned glass transition temperature Tg and melt flow rate MFR2 (260°C / 2.16 kg), the dispersibility of the cyclic olefin polymer (B) in the matrix of the polypropylene homopolymer (A) can be improved. In embodiments of the present invention, the content of cyclic olefin units such as norbornene units is in the range of 82 to 86% by mass, preferably 82.5 to 85.0% by mass, more preferably 82.5 to 84.0% by mass, and particularly about 83% by mass, based on the total mass of the cyclic olefin polymer (B). Furthermore, the content of acyclic olefin units, preferably α-olefin units such as ethylene units, is in the range of 14 to 18% by mass, preferably 15.0 to 17.5% by mass, more preferably 16.0 to 17.5% by mass, and particularly about 17.0% by mass, based on the total mass of the cyclic olefin polymer (B).

[0017] In this embodiment of the present invention, when the content of cyclic olefin units such as norbornene units is in the range of 82 to 86% by mass, the corresponding cyclic olefin polymer (B) is preferably Glass transition temperature (Tg) measured according to ISO 11357 in the range of 170-185°C, more preferably in the range of 175-180°C, particularly a glass transition temperature Tg of about 178°C; and / or The melt flow rate MFR2 (260°C / 2.16 kg), as measured according to ISO 1133, is in the range of 0.5 to 5 g / 10 min, more preferably 1 to 5 g / 10 min, and particularly about 2 g / 10 min. Similar to the above-described reference embodiment, if the cyclic olefin polymer is the cyclic olefin polymer in this embodiment according to the present invention, i.e., the above-described content of cyclic olefin units such as norbornene units in the range of 82 to 86% by mass, and one or both of the above-described glass transition temperature Tg and melt flow rate MFR2 (260°C / 2.16 kg), then the dispersibility of the cyclic olefin polymer (B) in the matrix of the polypropylene homopolymer (A) can be improved. Non-limiting examples of cyclic olefin polymers that meet the above specifications are polymers commercially available as APEL® from Mitsui Chemicals or TOPAS® from TOPAS Advanced Polymers.

[0018] additives The additives may be conventional additives used as processing aids for film manufacturing and / or added to a composition to achieve or improve desired properties of the film being manufactured, for example, to ensure favorable positive effects on manufacturing, storage, processing, or product characteristics. 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, nucleating agents, colorants, plasticizers, slip agents, anti-scratch agents, dispersants, processing aids, lubricants, pigments, antistatic agents, reinforcing agents, flame retardants, etc. Preferably, the additives are selected from the group consisting of antioxidants, stabilizers, acid scavengers and nucleating agents. 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.

[0019] 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. Therefore, one or more additives may be selected from the group consisting of, for example, pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate) (trade names Irganox 1010, Anox 20, Ethanox 310 TF and Kinox-10), butylhydroxytoluene (trade names Ionol CP and Vulkanox BHT), calcium stearate, and combinations thereof.

[0020] In one embodiment, the nucleating agent may be a beta nucleating agent. The term "beta nucleating agent" refers to any nucleating agent suitable for inducing the crystallization of hexagonal or pseudohexagonal propylene polymers. Mixtures of such nucleating agents may also be used. Suitable types of β-nucleating agents include C5-C8 cycloalkyl monoamines or C6-C 12 Aromatic monoamines and C5-C8 aliphatic, C5-C8 alicyclic, or C6-C 12 Aromatic dicarboxylic acids, for example: N,N'-di-C5-C8-cycloalkyl-2,6-naphthalenedicarboxamide compounds, for example: N,N'-Dicyclohexyl-2,6-Naphthalenedicarboxamide and N,N'-Dicyclooctyl-2,6-Naphthalenedicarboxamide N,N'-di-C5-C8-cycloalkyl-4,4-biphenyldicarboxamide compounds, for example: N,N'-Dicyclohexyl-4,4-biphenyldicarbosamide and N,N'-Dicyclopentyl-4,4-biphenyldicarbosamide, N,N'-di-C5-C8-cycloalkyl-terephthalamide compounds, for example: N,N'-Dicyclohexylterephthalamide and N,N'-Dicyclopentylterephthalamide, N,N'-C5-C8-cycloalkyl-1,4-cyclohexanedicarboxamide compounds, for example: N,N'-Dicyclohexyl-1,4-Cyclohexanedicarboxamide and N,N'-Dicyclohexyl-1,4-Cyclopentanedicarboxamide, C5-C8-cycloalkylmonocarboxylic acid or C6-C 12 - Aromatic monocarboxylic acids and C5-C8-alicyclic or C6-C 12 - Diamine derivative type diamide compounds derived from aromatic diamines, for example: N,N'-C6-C 12 -Arylene-bis-benzamide compounds, for example: N,N'-p-phenylene-bis-benzamide and N,N'-1,5-naphthalene-bis-benzamide N,N'-C5-C8-cycloalkyl-bis-benzamide compounds, for example: N,N'-1,4-cyclopentane-bis-benzamide and N,N'-1,4-cyclohexane-bis-benzamide N,N'-p-C6-C 12 -Arylene-bis-C5-C8-cycloalkylcarboxamide compounds, for example, the following: N,N'-1,5-naphthalene-bis-cyclohexanecarboxamide and N,N'-1,4-phenylene-bis-cyclohexanecarboxamide, and N,N'-C5-C8-cycloalkyl-bis-cyclohexanecarboxamide compounds, for example: N,N'-1,4-cyclopentane-bis-cyclohexanecarboxamide and N,N'-1,4-cyclohexane-bis-cyclohexanecarboxamide C5-C8-alkyl, C5-C8-cycloalkyl, or C6-C 12 -Aryl amino acids, C5-C8-alkyl-, C5-C8-cycloalkyl or C6-C 12 -Aromatic monocarboxylic acid chlorides and C5-C8-alkyl-, C5-C8-cycloalkyl or C6-C 12 - An amino acid derivative type diamide compound derived from the amidation reaction of an aromatic monoamine, for example, the following: N-phenyl-5-(N-benzoylamino)pentanamide and It is N-cyclohexyl-4-(N-cyclohexylcarbonylamino)benzamide.

[0021] Further suitable beta nucleating agents are as follows: Quinacridone-type compounds, for example 5,12-dihydro-quino[2,3-b]acridine-7,14-dione (i.e., quinacridone), dimethylquinacridone, and dimethoxyquinacridone; Quinacridone quinone type compounds, for example Quino[2,3-b]acridine-6,7,13,14(5H,12H)-tetron (i.e., quinacridone quinone), and dimethoxyquinacridone quinone and Dihydroquinacridone-type compounds, for example These are 5,6,12,13-tetrahydroquino[2,3-b]acridine-7,14-dione (i.e., dihydroquinacridone), dimethoxydihydroquinacridone, and dibenzodihydroquinacridone.

[0022] Further suitable β-nucleating agents include dicarboxylates of metals from Group 11a of the periodic table, such as calcium pimephosphate and calcium suberate; as well as mixtures of dicarboxylates with salts of metals from Group 11a of the periodic table.

[0023] 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 thickness of the film is preferably 1 to 1000 μm, more preferably 1 to 300 μm, and most preferably 1 to 250 μm. If the film is a cast film, the film thickness is preferably 100 to 1000 μm, more preferably 200 to 300 μm. If the film is a biaxially oriented film, the film thickness may be 1 to 100 μm, for example, 1 to 10 μm. Current attempts are to provide electrical systems with higher energy density and higher efficiency, and reducing thickness is particularly advantageous. Achieving this goal is facilitated by reducing the spatial requirements for the film within the film capacitor. When provided as a cast film with a thickness of 250 μm, the dielectric breakdown field strength of the film is E b 63.2% is preferably 118 kV / mm or higher, preferably 122 kV / mm or higher, and particularly 125 kV / mm or higher, as determined by IEC 60243-1 and IEC 62539 at 90°C. For example, the dielectric breakdown field strength E of a cast film measured by IEC 60243-1 using a thickness of 250 μm at 90°C and subsequently evaluated by IEC 62539. b 63.2% may be in the range of 118-250kV / mm, preferably 122-200kV / mm, and more preferably 125-190kV / mm.

[0024] The conductivity of the cast film according to the present invention may be 1.0 fS / cm or less, preferably less than 0.5 fS / cm. For example, the conductivity of the cast film may be 0.01 to 1.0 fS / cm, preferably less than 0.05 fS / cm to 0.5 fS / cm. In this case, the conductivity is taken as the reciprocal of the DC electrical resistance measured at a temperature of 90°C on a 250 μm thick film 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 polypropylene composition is extruded through a flat die to produce a non-oriented film. In the second step, the unstretched film is stretched in the machine direction (MD) and the transverse direction (TD). The stretching or orientation of the unstretched 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, after recovering the unstretched film, it may be cooled and solidified on a rotating cooling roll and then continuously transported from the cooling roll to a stretching device.

[0026] 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 or essentially consists of the same. It is even more preferable that the biaxially oriented polypropylene film essentially consists of the polypropylene composition defined in the present invention. The biaxially oriented polypropylene film preferably has a longitudinal stretch ratio of at least 4, preferably at least 5, and transverse stretch ratio of at least 4, preferably at least 5, and more preferably a longitudinal stretch ratio of at least 9 and transverse stretch ratio of at least 5. Biaxially oriented polypropylene films can be prepared by any conventional stretching process known in the industry. Therefore, a method for producing biaxially oriented polypropylene films can preferably utilize the tenter method known in the industry. The tenter method is a method for obtaining an unstretched 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 with 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 can be treated by corona discharge in air, nitrogen, carbon dioxide gas, or a mixture thereof. When the film is metallized for film capacitor applications, corona discharge treatment increases the adhesion strength to the deposited metal.

[0027] Capacitor In other embodiments, the present invention relates to a capacitor comprising the above-described biaxially oriented film. A capacitor comprising this 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. Metallization of the biaxially oriented film can be carried out by any method known in the art, such as 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). The 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]

[0028] [Figure 1] (a) to (c) are atomic force microscope images of some exemplary materials. [Modes for carrying out the invention]

[0029] 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 13For 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 stereosynthesis (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. 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 was possible through the integration of 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.

[0030] 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). XCS content The XCS content was determined as mass % at 23°C according to ISO 16152. 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 a nitrogen atmosphere (50 mL / min) with a heating / cooling / heating cycle at a scanning speed of 10 K / min between -30°C and 225°C, according to ISO 11357 / 3, using 5 ± 0.5 mg of sample. 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.

[0031] 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 conducted.

[0032] Dielectric breakdown measurement Dielectric breakdown strength (also called "dielectric breakdown field strength"), generally expressed in kV / mm, is a characteristic of gases, liquids, and solids. When the electric field exceeds the breakdown field, breakdown occurs through discharge channels in the material, and electrodes are connected. In solids, the material is irreversibly destroyed by 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.

[0033] Dielectric breakdown test The fracture 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).

[0034] Statistical evaluation IEC 62539, for evaluating breakdown distributions (also known as "DBDs"), includes the two-parameter Weibull distribution (2-Weibull), the three-parameter Weibull distribution (3-Weibull), the log-normal distribution, and the first asymptotic extremum distribution (1 AEV). Generally, when the breakdown mechanism is unknown, the statistical distribution is selected primarily through fitting quality. However, most inventors use the Weibull distribution, whose cumulative density distribution function for its three parameters is given by Equation 1.

[0035]

number

[0036] DC conductivity DC conductivity was calculated as the reciprocal of the DC electrical resistance measured at 90°C according to ASTM D257.

[0037] 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.

[0038] material The example materials were prepared using the polymers listed in Table 1 below. Table 1: Polymers used in the preparation of example materials

[0039] [Table 1] The above polymers were selected and / or combined in the amounts shown in Table 2 below to obtain materials for several examples. The components were melt-blended to obtain comparative example material CE2, example material IE1 of the present invention, and reference example material RE1. Comparative example material CE1 corresponds to a pure propylene homopolymer. Table 2: Composition of sample materials

[0040] [Table 2] Film samples were manufactured from sample material using a small laboratory cast 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 the melting temperature was also 235°C, recorded after 45 minutes of process stabilization. Following the extruder was a 300 mm wide die. The die had 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 morphology of the films prepared from CE2, as well as from RE1 and IE1, was examined using atomic force microscopy. This allowed for the examination of the 20 × 20 μm of the sample. 2 The dispersion characteristics within a large surface area were determined with respect to the d90 value of the ethylene norbornene copolymer domain. The results are shown in Table 3 below. In this context, it should be understood that 90% of the particles have a size less than the reported d90 value, i.e., possess maximum elongation. Table 3: Film 20 × 20 μm 2 Dispersion characteristics on a large surface area

[0041] [Table 3] As can be seen from Table 3 and Figures 1(a), (b), and (c) corresponding to the atomic force microscope images of films CE2, RE1, and IE1, respectively, the film IE1 of the present invention and the reference film RE1 exhibit very small and therefore finely dispersed inclusions. At least 90% of the ethylene norbornene copolymer domains in these films have a size of less than 2.0 μm. Therefore, the dispersion quality in film IE1 of the present invention is excellent, while the comparative film CE2 has a considerable proportion of ethylene norbornene copolymer domains with a size greater than 2.0 μm. Furthermore, the dielectric breakdown voltage and DC conductivity were measured for comparative films CE1 and CE2, the film IE1 of the present invention, and the reference film RE1 using the method described above. The results are shown in Table 4 below. Table 4

[0042] [Table 4] As can be seen from Table 4, the film IE1 and reference film RE1 of the present invention exhibit significantly better dielectric breakdown voltages than the comparative films CE1 and CE2. Furthermore, the film and reference film of the present invention have DC conductivity that is at least equivalent to or even better than that of the comparative films.< / mmmm>

Claims

1. A polypropylene composition, wherein the following applies to the total mass of the polypropylene composition 83-87% by mass of propylene homopolymer (A), and A cyclic olefin polymer (B) containing cyclic olefin units and acyclic olefin units in a concentration of 13 to 17% by mass. A polypropylene composition comprising, wherein the content of the cyclic olefin units is in the range of 82 to 86% by mass with respect to the total mass of the cyclic olefin polymer (B).

2. Melt flow rate (MFR) of propylene homopolymer (A), as measured according to ISO 1133. 2 The polypropylene composition according to claim 1, wherein the concentration (at 260℃ / 2.16 kg) is 1.0 to 10 g / 10 min, 1.0 to 7.0 g / 10 min, or 1.0 to 5.0 g / 10 min.

3. The polypropylene composition according to claim 1 or 2, wherein the ash content of the propylene homopolymer (A), as measured by ISO 3451-1 (1997), is 60 ppm or less or 30 ppm or less.

4. The propylene homopolymer (A) is either a high-isotactic polypropylene or １３ The polypropylene composition according to any one of claims 1 to 3, wherein the isotactic pentad fraction content measured by 13C NMR spectroscopy is 93-99.5%, 95-99.0%, or 96-98.5%.

5. The polypropylene composition according to any one of claims 1 to 4, wherein the xylene-soluble content of the propylene homopolymer (A), as measured by ISO 16152, is 0.1 to 4.0% by mass or 0.3 to 2.0% by mass.

6. The polypropylene composition according to claim 1, wherein the crystallization temperature (Tc) of the propylene homopolymer (A), as measured by ISO 11357, is 110 to 130°C.

7. The cyclic olefin polymer (B) The glass transition temperature (Tg) measured according to ISO 11537 is in the range of 170–185°C or 175–180°C, and / or Melt flow rate (MFR) measured according to ISO 1133 2 The polypropylene composition according to any one of claims 1 to 6, wherein the concentration (at 260℃ / 2.16 kg) is in the range of 0.5 to 5 g / 10 min or 1 to 5 g / 10 min.

8. The cyclic olefin unit is selected from the group consisting of cyclopentadiene units, norbornene units, tetracyclododecene units and their derivatives, or is a norbornene unit, and The acyclic olefin unit is a linear C2-C8α olefin unit or an ethylene unit. The polypropylene composition according to claim 1.

9. A film comprising the polypropylene composition according to any one of claims 1 to 10, which is an unoriented cast film or a biaxially oriented film.

10. Dielectric breakdown field strength E b The film according to claim 9, wherein 63.2% is an unstretched cast film having a dielectric breakdown field strength of 118 kV / mm or higher, 122 kV / mm or higher, or 125 kV / mm or higher, where the dielectric breakdown field strength E b 63.2% of the film is measured at a temperature of 90°C on a 250 μm thick film according to IEC 60243-1 and determined according to IEC 62539.

11. The film according to claim 9 or 10, which is a non-oriented cast film having an conductivity of 1 fS / cm or less or less than 0.5 fS / cm when converted as the reciprocal of the DC electrical resistance measured on a 250 μm thick film at a temperature of 90°C according to ASTM D257.

12. A capacitor comprising the film according to claim 9, wherein the film is a biaxially oriented film.

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