A CBC-containing olefin polymer film and preparation method thereof

Abstract

The invention discloses an olefin polymer film containing CBC and a preparation method thereof, and relates to the technical field of olefin polymer films. The film is made of the following components by mass percentage: 10-45wt% of a cyclic block copolymer with a glass transition temperature of 115-128°C, 55-85wt% of a partially crystallized propylene homopolymer with a crystal melting temperature of 150-170°C, and 0.1-5wt% of an additive. The invention uses domestic CBC raw materials to replace imported COC, thereby effectively reducing production costs, reducing dependence on imported raw materials, and significantly enhancing the autonomy and competitiveness of the domestic electronic component industry. The prepared film material exhibits excellent thermal stability, greatly improving the dimensional stability and reliability of capacitors in high temperature environments. At the same time, the film material has excellent electrical properties, meeting the stringent requirements of capacitors for insulating media.

Description

Technical Field

[0001] The invention relates to the technical field of olefin polymer films, and in particular to an olefin polymer film containing CBC and a preparation method thereof. Background Art

[0002] As an indispensable basic component in modern electronic and electrical equipment, the performance of capacitors directly affects the reliability and efficiency of the entire system. In capacitor manufacturing, the selection of insulating materials is particularly critical. At present, biaxially oriented polypropylene film (BOPP film) has become one of the preferred materials for capacitor insulation due to its excellent electrical and mechanical properties.

[0003] However, the performance of traditional BOPP film in high temperature environment is still insufficient. Especially at temperatures above 100°C, the film material shows a high shrinkage rate, which not only causes the capacitor to deform, but also may affect the integrity of the metallization layer on the surface of the film, and ultimately endanger the function of the capacitor. Severe aging of the film during long-term use is also an important reason for the deterioration of its dielectric properties. Therefore, the development of polyolefin film materials with better high temperature stability has become the focus of industry research.

[0004] To improve the performance of BOPP film, researchers tried to introduce cyclic olefin copolymer (COC) into propylene homopolymer. COC is an amorphous thermoplastic resin copolymerized by cyclic olefin monomers (such as norbornene) and α-olefins (such as ethylene) through metal catalysts. It has the characteristics of high transparency, low density, low hygroscopicity, excellent chemical resistance, high heat deformation temperature, low dielectric constant and dielectric loss. These characteristics enable COC to significantly improve the heat resistance, dielectric properties and dimensional stability of film materials.

[0005] Another potential modified material is cyclic block copolymer (CBC). CBC is copolymerized by cyclic olefin monomers (such as cyclic dimers of 1-butene) and α-olefins (such as ethylene), and has the characteristics of high transparency, good flexibility, low melting point, excellent barrier properties and good compatibility. Although the application research of CBC in the field of capacitors is relatively small, its good compatibility and low melting point may have potential advantages in modifying propylene homopolymer.

[0006] Chinese patent document CN110546190B discloses a biaxially stretched polyolefin film comprising the following components: (a) 10 to 45 wt % of a cycloolefin polymer having a glass transition temperature between 120 and 170°C, and (b) 90 to 55 wt % of a partially crystallized α-olefin polymer having a crystalline melting temperature between 150 and 170°C, wherein the glass transition temperature of component (a) is less than or equal to the crystalline melting temperature of component (b), and the polyolefin film has a shrinkage of less than or equal to 2% measured according to DIN ISO 11501 after 5 minutes at 130°C.

[0007] In view of this, it is particularly urgent to develop a new type of propylene homopolymer film for capacitors that does not rely on COC raw materials and can achieve the same performance requirements as existing films. This new film needs to have the following characteristics: extremely small dielectric loss factor to ensure high efficiency and low heat generation of the capacitor; extremely small shrinkage, especially in high temperature environments, to maintain the dimensional stability of the capacitor; low friction coefficient to facilitate film processing and capacitor assembly; excellent electrical insulation performance to meet the insulation requirements of motors, transformers and other equipment; good mechanical strength to ensure reliability during use.

[0008] The present invention aims to solve the above technical problems and provide a new type of polyolefin film material and a preparation method thereof to meet the needs of the capacitor manufacturing industry for high-performance, high-reliability insulating media, while reducing dependence on imported raw materials and enhancing the autonomy and competitiveness of the domestic electronic component industry. Summary of the invention

[0009] In order to solve the shortcomings of the prior art, the purpose of the present invention is to provide an olefin polymer film containing CBC and a preparation method thereof. The olefin polymer film containing CBC has excellent electrical properties, thermal stability, long-term stability, mechanical properties and environmental friendliness, which provides a new direction for the development of insulating materials for capacitors and also opens up broad application prospects for material development in related fields.

[0010] In order to achieve the above object, the present invention adopts the following technical solution:

[0011] A CBC-containing olefin polymer film is prepared from the following components by mass percentage: 10-45wt% of a cyclic block copolymer with a glass transition temperature of 115-128°C, 55-85wt% of a partially crystallized propylene homopolymer with a crystal melting temperature of 150-170°C, and 0.1-5wt% of an additive.

[0012] Preferably, the additive is one or more of a processing aid, a plasticizer, a UV stabilizer, a matting agent, a preservative, a biocide, an antioxidant, an antistatic agent, a fire retardant, a reinforcing agent, a filler, a pigment, and a fuel.

[0013] Preferably, the chemical formula of the cyclic block copolymer is as follows:

[0014] ,

[0015] Wherein, a, b, c are positive integers ≥ 1, x and y are positive integers ≥ 1, and R1 and R2 are independently alkyl or hydrogen.

[0016] Preferably, the cyclic block copolymer has a haze of less than 0.5% and a transmittance (380-760 nm) of less than 92% measured according to ASTM D1003;

[0017] Preferably, the cyclic block copolymer has a Vicat softening temperature (1 kg, 50°C / h) of 109-125°C measured according to ASTM D1525, and a heat deformation temperature (0.455 MPa, 2°C / min) of 83-103°C measured according to ASTM D648;

[0018] Preferably, the cyclic block copolymer has a flexural strength of 56-70 MPa and a flexural modulus of 1.5-2.3 GPa measured according to ASTM D790;

[0019] Preferably, the cyclic block copolymer has a tensile strength at breaking point of 28-37 MPa and an elongation of 12-80% measured according to ASTM D638;

[0020] Preferably, the cyclic block copolymer has a notched impact strength of 30 to 135 J / m measured according to ASTM D256, and a notched impact strength of 2.8 to 13.5 kJ / m measured according to ASTM D6110. 2 ;

[0021] Preferably, the cyclic block copolymer has a density of 0.93 to 0.95 g / cm2 as measured according to ASTM D792. 3 ;

[0022] Preferably, the cyclic block copolymer has a water absorption of less than 0.01% measured according to ASTM D570;

[0023] Preferably, the cyclic block copolymer has a melt flow rate (2.16 kg, 260° C.) of 5 to 13 as measured according to ASTM D1238;

[0024] Preferably, the cyclic block copolymer has a melt flow rate (2.16 kg, 260° C.) of 200 as measured according to ASTM D1238;

[0025] Preferably, the refractive index of the cyclic block copolymer is 1.51;

[0026] Preferably, the cyclic block copolymer has a yellowing index of less than 0.5 measured according to ASTM G154;

[0027] Preferably, the cyclic block copolymer has a loss factor of less than or equal to 0.00016 at a thickness of 50 μm and a 10 GHz test method DEA;

[0028] Preferably, the cyclic block copolymer has a loss factor of less than or equal to 0.00018 at a thickness of 100 μm and a 10 GHz test method DEA;

[0029] Preferably, the cyclic block copolymer has a loss factor of less than or equal to 0.00041 at a thickness of 200 μm and a 10 GHz test method DEA;

[0030] Preferably, the CBC-containing olefin polymer film is measured according to DIN ISO 11501. When the thickness is 3.8 μm and the temperature varies in the range of 100 to 140° C., its longitudinal heat shrinkage is 1 to 3.2%, and its transverse heat shrinkage is 0.2 to 1.1%; the surface roughness of the CBC-containing olefin polymer film is 0.4 to 0.6 μm.

[0031] Preferably, the CBC-containing olefin polymer film has a dielectric strength of 521-576 V / μm.

[0032] Preferably, the CBC-containing olefin polymer film has an electrical strength of 589-475 V / μm or 518-347 V / μm when the temperature rises from 65° C. to 125° C.

[0033] Preferably, the CBC-containing olefin polymer film is a single-layer film or a multi-layer film, and at least one film in the multi-layer film is the CBC-containing olefin polymer film.

[0034] Preferably, the additive is a composite antioxidant, the mass percentage of which is 0.1-5wt%, and the preparation method comprises the following steps:

[0035] (1) Add melamine and 3,5-di-tert-butyl-4-hydroxybenzaldehyde to DMF under light-proof conditions, mix well, then add p-toluenesulfonic acid, stir to react, cool the product, pour into ice water and stir until precipitation, filter the precipitate, wash with ice water, and vacuum dry to obtain an intermediate;

[0036] Schiff base reaction: Melamine reacts with 3,5-di-tert-butyl-4-hydroxybenzaldehyde in DMF solvent under the catalysis of p-toluenesulfonic acid. The amino group (-NH2) of melamine acts as a nucleophilic reagent to attack the carbon atom of the aldehyde group of 3,5-di-tert-butyl-4-hydroxybenzaldehyde; p-toluenesulfonic acid acts as an acid catalyst to promote the activation of the aldehyde group; a nucleophilic addition reaction occurs to form an unstable intermediate; finally, the intermediate loses a molecule of water to form a carbon-nitrogen double bond (C=N), i.e., a Schiff base structure. The result of this reaction is the formation of an imine bond (C=N) between the amino group of melamine and benzaldehyde.

[0037] Preferably, in step (1), the molar ratio of melamine, 3,5-di-tert-butyl-4-hydroxybenzaldehyde and p-toluenesulfonic acid is 1:1-3:0.001-0.01.

[0038] Preferably, in step (1), the stirring reaction condition is 60-100° C. for 2-6 hours.

[0039] (2) Dissolve the intermediate in tetrahydrofuran under light-proof conditions, add hexadecyl mercaptan and azobisisobutyronitrile, stir and react under a nitrogen atmosphere, cool the product, remove the solvent by rotary evaporation, add ethanol and cool, collect the crystals by suction filtration, wash with ice-cold ethanol, and vacuum dry to obtain the composite antioxidant.

[0040] Thiol-ene click reaction: The intermediate obtained in the first step (containing a C=N double bond) undergoes a free radical addition reaction with hexadecyl mercaptan in tetrahydrofuran solvent under the initiation of azobisisobutyronitrile (AIBN). AIBN decomposes under heating conditions to produce free radicals; the free radicals react with hexadecyl mercaptan to form thiol radicals; the thiol radicals attack the C=N double bond of the Schiff base intermediate to form a carbon radical intermediate; the carbon radical captures a hydrogen atom from another hexadecyl mercaptan molecule to complete the addition reaction, while regenerating thiol radicals to continue the chain reaction. The result of this reaction is that hexadecyl mercaptan is added to the C=N double bond of the Schiff base to form a CS bond.

[0041] Preferably, in step (2), the molar ratio of the intermediate, hexadecyl mercaptan and azobisisobutyronitrile is 1:1-3:0.001-0.01.

[0042] Preferably, in step (2), the stirring reaction conditions are 40-65° C. for 2-8 h.

[0043] Preferably, the additive is a composite antioxidant, the mass percentage is 0.1-5wt%, which can be 0.1wt%, 0.2wt%, 0.3wt%, 0.4wt%, 0.5wt%, 0.6wt%, 0.7wt%, 0.8wt%, 0.9wt%, 1wt%, 1.5wt%, 2wt%, 2.5wt%, 3wt%, 3.5wt%, 4wt%, 4.5wt%, 5wt%; its structural formula is one or more of Formula I, Formula II, and Formula III:

[0044] (I);

[0045] (II);

[0046] (III);

[0047] In the formula, R3 is -(CH2) 15 -CH3.

[0048] The present invention also claims a use of the CBC-containing olefin polymer film in a capacitor.

[0049] The present invention also claims protection for a method for preparing the CBC-containing olefin polymer film, which is a biaxial stretching technology targeted at the PP / CBC blending system, comprising the following steps: putting a propylene homopolymer, a cyclic block copolymer and an additive into a mixing device and mixing them evenly, feeding them into an extruder, and the extruder plasticizes the mixed melt through seven stages of heating and stabilizing pressure to ensure that the raw materials are fully plasticized and blended, the melt is filtered through two stages, metered and extruded to a chilled roller, and the chilled roller cools the melt to obtain a thick sheet to be stretched; heating in a preheating zone of a synchronous stretching oven, and transversely stretching it into a film at a higher temperature to ensure that the rigid CBC chain and the flexible PP chain have high molecular chain mobility at the same time; and winding up after trimming, thickness measurement and corona treatment to obtain the CBC-containing olefin polymer film.

[0050] Preferably, the temperatures of the seven sections of the extruder are respectively 235-245°C for the feeding section I-II, 250-265°C for the melting section III-V, and 250-260°C for the homogenizing section VI-VII; the metering pump speed is 25-35r / min, the extruder speed is 25-35r / min, the chilled roller temperature is 75-85°C, and the chilled roller speed is 40-50r / min; the preheating zone temperature is 155±2°C, 158±2°C, 161±2°C, and 163±2°C; the corona treatment power is 19±1Wmin / m 2 ;Film winding tension 30±3N / m.

[0051] Compared with the prior art, the present invention has the following beneficial effects:

[0052] (1) The present invention provides an olefin polymer film containing CBC, which successfully achieves a comprehensive improvement in the performance of capacitor films by compounding cyclic block copolymers (CBC) with propylene homopolymers. The film material exhibits excellent thermal stability, greatly improving the dimensional stability and reliability of capacitors in high temperature environments. At the same time, the film material has excellent electrical properties, meeting the stringent requirements of capacitors for insulating media. The present invention uses domestic CBC raw materials to replace imported COC, which not only effectively reduces production costs, but also reduces dependence on imported raw materials, significantly enhancing the autonomy and competitiveness of the domestic electronic component industry. This high-performance, high-reliability olefin polymer film provides a new type of insulating medium solution for the capacitor manufacturing industry, and is expected to promote technological progress and innovative development in related industries.

[0053] (2) The present invention provides a synchronous biaxial stretching technology that matches the PP / CBC blending system. The notable features of this technology are that a more finely differentiated extrusion segment design and a higher melt extrusion temperature are used to ensure that the two materials are fully blended and plasticized, and a higher stretching temperature is used to ensure that the CBC molecular chain and the PP molecular chain achieve a higher molecular chain mobility that matches. This process can produce PP / CBC blended films that have a thickness similar to that of pure PP films (~3.8μm) and have a higher crystal melting point and a higher glass transition temperature.

[0054] (3) The present invention provides a method for preparing a composite antioxidant. In the first step, melamine and 3,5-di-tert-butyl-4-hydroxybenzaldehyde react through a Schiff base to form an intermediate with a large π-bond conjugated system, thereby enhancing the stability of the molecule. In the second step, hexadecyl mercaptan is introduced into the molecular structure through a free radical addition reaction, which not only further increases the molecular weight but also improves the compatibility and dispersibility of the antioxidant. This multi-step synthesis strategy enables the final product to have multiple antioxidant mechanisms, including free radical capture, peroxide decomposition, and metal chelation.

[0055] (4) The present invention provides a composite antioxidant, which achieves multiple synergistic effects through ingenious design and significantly improves the comprehensive performance of olefin polymer films. By rationally combining triazine, di-tert-butylphenol and long-chain alkyl, the red shift of the maximum absorption wavelength of the antioxidant is achieved, and the thermal stability and compatibility with the propylene homopolymer matrix are improved. The antioxidant combines the free radical capture ability of phenolic antioxidants and the peroxide decomposition ability of sulfur-based compounds to form a highly efficient synergistic antioxidant effect, significantly improving the aging resistance and long-term effectiveness of the film and extending the service life of the product. At the same time, it enhances the interaction between molecular chains and improves the mechanical properties of the material. The macromolecular structure design reduces the volatility and migration of the antioxidant, ensuring a long-term and stable protective effect. This antioxidant is not only suitable for the CBC-containing olefin polymer film of the present invention, but can also be applied to other materials or products that require long-term antioxidant protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show schematic diagrams of certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0057] Figure 1 The DSC melting curves (a) and dynamic thermomechanical analysis spectra (b) of the olefin polymer films prepared in Comparative Examples 2, 3, and 4 are shown. DETAILED DESCRIPTION

[0058] In order to make the purpose, technical solution and advantages of the present invention clearer, the present invention is further described in detail below in conjunction with embodiments. Of course, the specific embodiments described here are only used to explain the present invention and are not used to limit the present invention.

[0059] Unless otherwise specified, the chemical reagents and materials in the present invention are purchased from commercial sources or synthesized from raw materials purchased from commercial sources.

[0060] The cyclic block copolymers were provided by Taiwan Polymer Chemicals Co., Ltd., models are ViviOn8210XT and CBC0645;

[0061] The propylene homopolymer is high-purity PP (capacitor grade), purchased from Borealis AG, model BorcleanHC300BF, Borclean HC310BF; in addition, Singapore FS3030, FS3031, Korea's HPT-1, HPT-V can also be selected;

[0062] Cyclic olefin polymer was purchased from TOPAS Advanced Polymers GmbH, Frankfurt am Main, model TOPAS 6013.

[0063] A method for preparing an olefin polymer film containing CBC comprises the following steps:

[0064] (1) Add 0.01 mol of melamine and 0.01-0.03 mol of 3,5-di-tert-butyl-4-hydroxybenzaldehyde to 50 mL of DMF under light-proof conditions, mix well, then add 0.00001-0.0001 mol of p-toluenesulfonic acid, stir and react at 60-100°C for 2-6 hours, cool the product, pour it into ice water and stir until precipitation, filter the precipitate, wash with ice water, and vacuum dry to obtain an intermediate;

[0065] (2) Dissolve 0.01 mol of the intermediate in 50 mL of tetrahydrofuran under light-proof conditions, add 0.01-0.03 mol of hexadecyl mercaptan and 0.00001-0.0001 mol of azobisisobutyronitrile, and react under nitrogen atmosphere at 40-65° C. with stirring for 2-8 hours. Cool the product, remove the solvent by rotary evaporation, add ethanol and cool, cool the mixture in a refrigerator to promote crystallization, collect the crystals by suction, wash with ice-cold ethanol, and vacuum dry to obtain the composite antioxidant;

[0066] (3) 10~45wt% of cyclic block copolymer, 55~85wt% of propylene homopolymer and 0.1~5wt% of composite antioxidant are put into a mixing device and mixed evenly, and then fed into an extruder. The extruder is plasticized into a mixed melt through seven-stage heating and stabilizing pressure. The seven-stage temperatures of the extruder are feeding section I~II 235~245℃, melting section III~V 250~265℃, homogenizing section VI~VII 250~260℃; the melt is filtered in two stages and extruded to the chilled roller. The chilled roller cools the melt to obtain a thick sheet to be stretched. The metering pump speed is 25~35r / min, the extruder speed is 25~35r / min, the chilled roller temperature is 75~85℃, and the chilled roller speed is 40~50r / min; it is heated in the preheating zone of the synchronous stretching oven and stretched horizontally into a film. The preheating zone temperature is 155±2℃, 158±2℃, 161±2℃, and 163±2℃; it is rolled up after trimming, thickness measurement, and corona treatment. The corona treatment power is 19±1Wmin / m 2 , the film winding tension is 30±3N / m, and the CBC-containing olefin polymer film is obtained.

[0067] The present invention will be further described below through specific embodiments. Example 1

[0068] A method for preparing an olefin polymer film containing CBC comprises the following steps:

[0069] (1) Add 0.01 mol of melamine and 0.03 mol of 3,5-di-tert-butyl-4-hydroxybenzaldehyde to 50 mL of DMF under light-proof conditions, mix well, then add 0.0001 mol of p-toluenesulfonic acid, stir and react at 100°C for 2 h, cool the product, pour it into ice water and stir until precipitation, filter the precipitate, wash with ice water, and vacuum dry to obtain an intermediate;

[0070] (2) Dissolve 0.01 mol of the intermediate in 50 mL of tetrahydrofuran under light-proof conditions, add 0.03 mol of hexadecyl mercaptan and 0.0001 mol of azobisisobutyronitrile, and stir the mixture at 65° C. in a nitrogen atmosphere for 2 h. Cool the product and remove the solvent by rotary evaporation. Add ethanol and cool the mixture. Cool the mixture in a refrigerator to promote crystallization. Collect the crystals by suction, wash with ice-cold ethanol, and vacuum dry to obtain the composite antioxidant.

[0071] (3) 300 g of cyclic block copolymer, 650 g of propylene homopolymer and 50 g of composite antioxidant were put into a mixing device and mixed evenly, and then fed into an extruder. The extruder was heated and pressure-stabilized in seven stages to plasticize the mixed melt. The temperatures of the seven stages of the extruder were feeding stage I~II 240°C, melting stage III~V 250°C, 260°C, 260°C, homogenization stage VI~VII. 260℃, 255℃; the melt is filtered in two stages and extruded to the chilled roller. The chilled roller cools the melt to obtain a thick sheet to be stretched. The metering pump speed is 25.9r / min, the extruder speed is 30r / min, the chilled roller temperature is 80℃, and the chilled roller speed is 45r / min; it is heated in the preheating zone of the synchronous stretching oven and stretched horizontally into a film. The preheating zone temperature is 155±2℃, 158±2℃, 161±2℃, 163±2℃; it is wound after trimming, thickness measurement, and corona treatment. The corona treatment power is 19±1Wmin / m 2 , the film winding tension is 30±3N / m, and the CBC-containing olefin polymer film is obtained. Example 2

[0072] A method for preparing an olefin polymer film containing CBC comprises the following steps:

[0073] (1) Add 0.01 mol of melamine and 0.02 mol of 3,5-di-tert-butyl-4-hydroxybenzaldehyde to 50 mL of DMF under light-proof conditions, mix well, then add 0.00005 mol of p-toluenesulfonic acid, stir and react at 80°C for 4 h, cool the product, pour it into ice water and stir until precipitation, filter the precipitate, wash with ice water, and vacuum dry to obtain an intermediate;

[0074] (2) Dissolve 0.01 mol of the intermediate in 50 mL of tetrahydrofuran under light-proof conditions, add 0.02 mol of hexadecyl mercaptan and 0.00005 mol of azobisisobutyronitrile, and stir the mixture at 55° C. in a nitrogen atmosphere for 5 h. Cool the product and remove the solvent by rotary evaporation. Add ethanol and cool the mixture. Cool the mixture in a refrigerator to promote crystallization. Collect the crystals by suction, wash with ice-cold ethanol, and vacuum dry to obtain the composite antioxidant.

[0075] (3) 300 g of cyclic block copolymer, 650 g of propylene homopolymer and 50 g of composite antioxidant were put into a mixing device and mixed evenly, and then fed into an extruder. The extruder was heated and pressure-stabilized in seven stages to plasticize the mixed melt. The temperatures of the seven stages of the extruder were feeding stage I~II 240°C, melting stage III~V 250°C, 260°C, 260°C, homogenization stage VI~VII. 260℃, 255℃; the melt is filtered in two stages and extruded to the chilled roller. The chilled roller cools the melt to obtain a thick sheet to be stretched. The metering pump speed is 25.9r / min, the extruder speed is 30r / min, the chilled roller temperature is 80℃, and the chilled roller speed is 45r / min; it is heated in the preheating zone of the synchronous stretching oven and stretched horizontally into a film. The preheating zone temperature is 155±2℃, 158±2℃, 161±2℃, 163±2℃; it is wound after trimming, thickness measurement, and corona treatment. The corona treatment power is 19±1Wmin / m 2 , the film winding tension is 30±3N / m, and the CBC-containing olefin polymer film is obtained. Example 3

[0076] A method for preparing an olefin polymer film containing CBC comprises the following steps:

[0077] (1) Add 0.01 mol of melamine and 0.01 mol of 3,5-di-tert-butyl-4-hydroxybenzaldehyde to 50 mL of DMF under light-proof conditions, mix well, then add 0.00001 mol of p-toluenesulfonic acid, stir and react at 60°C for 6 h, cool the product, pour it into ice water and stir until precipitation, filter the precipitate, wash with ice water, and vacuum dry to obtain an intermediate;

[0078] (2) Dissolve 0.01 mol of the intermediate in 50 mL of tetrahydrofuran under light-proof conditions, add 0.01 mol of hexadecyl mercaptan and 0.00001 mol of azobisisobutyronitrile, and stir the mixture at 40° C. in a nitrogen atmosphere for 8 h. Cool the product and remove the solvent by rotary evaporation. Add ethanol and cool the mixture. Cool the mixture in a refrigerator to promote crystallization. Collect the crystals by suction filtration, wash with ice-cold ethanol, and vacuum dry to obtain the composite antioxidant.

[0079] (3) 300 g of cyclic block copolymer, 650 g of propylene homopolymer and 50 g of composite antioxidant were put into a mixing device and mixed evenly, and then fed into an extruder. The extruder was heated and pressure-stabilized in seven stages to plasticize the mixed melt. The temperatures of the seven stages of the extruder were feeding stage I~II 240°C, melting stage III~V 250°C, 260°C, 260°C, homogenization stage VI~VII. 260℃, 255℃; the melt is filtered in two stages and extruded to the chilled roller. The chilled roller cools the melt to obtain a thick sheet to be stretched. The metering pump speed is 25.9r / min, the extruder speed is 30r / min, the chilled roller temperature is 80℃, and the chilled roller speed is 45r / min; it is heated in the preheating zone of the synchronous stretching oven and stretched horizontally into a film. The preheating zone temperature is 155±2℃, 158±2℃, 161±2℃, 163±2℃; it is wound after trimming, thickness measurement, and corona treatment. The corona treatment power is 19±1Wmin / m 2 , the film winding tension is 30±3N / m, and the CBC-containing olefin polymer film is obtained. Comparative Example 1

[0080] A method for preparing an olefin polymer film containing CBC comprises the following steps:

[0081] (1) Add 0.01 mol of melamine and 0.03 mol of 3,5-di-tert-butyl-4-hydroxybenzaldehyde to 50 mL of DMF under light-proof conditions, mix well, then add 0.0001 mol of p-toluenesulfonic acid, stir and react at 100°C for 2 h, cool the product, pour it into ice water and stir until precipitation, filter the precipitate, wash with ice water, and vacuum dry to obtain an intermediate;

[0082] (2) 300 g of cyclic block copolymer, 650 g of propylene homopolymer and 50 g of intermediate were put into a mixing device and mixed evenly, and then fed into an extruder. The extruder was heated and pressure-stabilized in seven stages to plasticize the mixed melt. The temperatures of the seven stages of the extruder were feeding stage I~II 240°C, melting stage III~V 250°C, 260°C, 260°C, homogenization stage VI~VII. 260℃, 255℃; the melt is filtered in two stages and extruded to the chilled roller. The chilled roller cools the melt to obtain a thick sheet to be stretched. The metering pump speed is 25.9r / min, the extruder speed is 30r / min, the chilled roller temperature is 80℃, and the chilled roller speed is 45r / min; it is heated in the preheating zone of the synchronous stretching oven and stretched horizontally into a film. The preheating zone temperature is 155±2℃, 158±2℃, 161±2℃, 163±2℃; it is wound after trimming, thickness measurement, and corona treatment. The corona treatment power is 19±1Wmin / m 2 , the film winding tension is 30±3N / m, and the CBC-containing olefin polymer film is obtained. Comparative Example 2

[0083] A method for preparing an olefin polymer film containing CBC comprises the following steps:

[0084] 350g of cyclic block copolymer and 650g of propylene homopolymer were put into a mixing device and mixed evenly, and then fed into an extruder. The extruder was heated and stabilized in seven stages to plasticize the mixed melt. The temperatures of the seven stages of the extruder were feeding stage I~II 240℃, melting stage III~V 250℃, 260℃, 260℃, homogenization stage VI~VII. 260℃, 255℃; the melt is filtered in two stages and extruded to the chilled roller. The chilled roller cools the melt to obtain a thick sheet to be stretched. The metering pump speed is 25.9r / min, the extruder speed is 30r / min, the chilled roller temperature is 80℃, and the chilled roller speed is 45r / min; it is heated in the preheating zone of the synchronous stretching oven and stretched horizontally into a film. The preheating zone temperature is 155±2℃, 158±2℃, 161±2℃, 163±2℃; it is wound after trimming, thickness measurement, and corona treatment. The corona treatment power is 19±1Wmin / m 2 , the film winding tension is 30±3N / m, and the CBC-containing olefin polymer film is obtained. Comparative Example 3

[0085] A method for preparing an olefin polymer film containing COC comprises the following steps:

[0086] 350g of cycloolefin polymer and 650g of propylene homopolymer were put into a mixing device and mixed evenly, and then fed into an extruder. The extruder was plasticized into a mixed melt through seven-stage heating and stabilizing pressure. The temperatures of the seven sections of the extruder were respectively 240℃ for feeding section I~II, 250℃, 260℃, 260℃ for melting section III~V, and 260℃, 255℃ for homogenizing section VI~VII; the melt was filtered through two stages and extruded to a chilled roller. The chilled roller cooled the melt to obtain a thick sheet to be stretched. The metering pump speed was 25.9r / min, the extruder speed was 30r / min, the chilled roller temperature was 80℃, and the chilled roller speed was 45r / min; the film was heated in the preheating zone of a synchronous stretching oven and stretched transversely into a film. The preheating zone temperatures were 155±2℃, 158±2℃, 161±2℃, and 163±2℃; the film was rolled up after trimming, thickness measurement, and corona treatment. The corona treatment power was 19±1Wmin / m 2 , the film winding tension is 30±3N / m, and the COC-containing olefin polymer film is obtained. Comparative Example 4

[0087] A method for preparing an olefin polymer film comprises the following steps:

[0088] 1000g of propylene homopolymer is fed into an extruder, which is plasticized into a mixed melt through seven-stage heating and stabilizing pressure. The temperatures of the seven sections of the extruder are respectively 230°C for feeding section I~II, 250°C for melting section III~V, and 245°C for homogenizing section VI~VII; the melt is filtered through two stages and metered and extruded to a chilled roller. The chilled roller cools the melt to obtain a thick sheet to be stretched. The metering pump speed is 25.9r / min, the extruder speed is 30r / min, the chilled roller temperature is 80°C, and the chilled roller speed is 45r / min; the melt is heated in a preheating zone of a synchronous stretching oven and stretched transversely into a film. The temperatures in the preheating zone are 150±2°C, 152±2°C, 155±2°C, and 158±2°C; the olefin polymer film is obtained after trimming, thickness measurement, and corona treatment and then winding. The corona treatment power is 19±1Wmin / m2, and the film winding tension is 30±3N / m.

[0089] The films prepared in Examples 1 to 3 and Comparative Examples 1 to 2 were tested for their anti-aging properties. 2 ) were placed in an ultraviolet lamp aging test chamber (model UVZN-320) and subjected to ultraviolet accelerated aging test according to the method described in ISO 4892.3 "Plastics laboratory light source exposure method Part 3 Fluorescent ultraviolet lamp". The test conditions are as follows: light source, UVA-340; radiation energy, 0.83W / (m 2 nm); test temperature, 70℃; 4 hours of light exposure, 1 hour of light off, 200 hours of cycle test; before and after aging, the tensile strength, elongation at break and its retention rate were tested with reference to GB / T 1040.3-2006 "Determination of tensile properties of plastics Part 3: Test conditions for films and sheets". Specific data are shown in Table 1.

[0090] Table 1 Test results of film anti-aging performance

[0091]

[0092] The performance of the olefin polymer films prepared in Comparative Examples 2 and 3 was tested, and the thermal shrinkage and breakdown strength were tested with reference to GB / T 13542.2-2021 "Films for electrical insulation Part 2: Test methods". The specific data are shown in Table 2.

[0093] Table 2 Performance test results of olefin polymer membranes containing CBC and COC

[0094]

[0095] The transverse and longitudinal heat shrinkage rates of the film (propylene homopolymer film containing CBC) prepared by the present application are similar to those of the existing film (propylene homopolymer film containing COC); and its shrinkage rate is lower in the range of 100°C to 120°C. This temperature range is the normal working temperature of the capacitor. A lower shrinkage rate is conducive to the flatness of the capacitor core after winding and hot pressing. A film with a large shrinkage rate will have many wrinkles after winding and hot pressing, and many wrinkles will cause the capacitor device to be more prone to aging and failure. The present application is more conducive to the production of downstream capacitor devices, improves the service life of capacitor devices and ensures safe use.

[0096] The electrical resistance of the propylene homopolymer film produced by CBC at 65°C and 125°C is similar to that of the existing propylene homopolymer film produced by COC, and the electrical resistance at 85°C and 105°C is better than that of the existing propylene homopolymer film produced by COC.

[0097] Therefore, the performance indicators of the propylene homopolymer film prepared by CBC in the present invention are similar to those of the existing propylene homopolymer film prepared by COC. The propylene homopolymer film prepared by the present application can replace the existing propylene homopolymer film for use, thereby reducing or getting rid of the dependence on foreign-controlled COC. At the same time, in the range of 100°C to 120°C, the capacitor core prepared by it is flatter after winding and hot pressing, ensuring the service life and performance of the capacitor device.

[0098] The polyolefin films prepared in Comparative Examples 2 to 4 were tested for crystal melting point according to GB / T 19466.3-2004, with a program heating rate of 10°C / min. Figure 1 Curve a in the figure. Dynamic mechanical analysis (DMA) was performed on Comparative Examples 2 to 4. The instrument used was DMA Q800 produced by TA Company of the United States. The test mode was tensile mode, the test temperature range was -70~150℃, the heating rate was 3℃ / min, and the amplitude was 10μm. For specific data, see Figure 1 Curve b in .

[0099] The melting point of the polyolefin film containing CBC prepared by the targeted biaxial stretching process of the present invention is similar to that of the film prepared by COC, and both are significantly higher than the pure BOPP film prepared by the ordinary biaxial stretching process. The glass transition temperature of the CBC film involved in the present invention is also similar to that of the film containing COC, both are higher than the pure BOPP film, and the chain segment activity ability hindering effect is similar.

[0100] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. An olefin polymer film containing CBC, characterized in that The invention is prepared from the following components by weight percentage: 10-45 wt% of a cyclic block copolymer having a glass transition temperature of 115-128°C, 55-85 wt% of a partially crystallized propylene homopolymer having a crystalline melting temperature of 150-170°C, and additives; The additive is a composite antioxidant, the mass percentage is 0.1-5wt%, and the structural formula is: ； In the formula, R3 is -(CH2) 15 -CH3; The additive is a composite antioxidant, the mass percentage of which is 0.1-5wt%, and the preparation method comprises the following steps: (1) Add melamine and 3,5-di-tert-butyl-4-hydroxybenzaldehyde to DMF under light-proof conditions, mix well, then add p-toluenesulfonic acid, stir to react, cool the product, pour into ice water and stir until precipitation, filter the precipitate, wash with ice water, and vacuum dry to obtain an intermediate; (2) Dissolve the intermediate in tetrahydrofuran under light-proof conditions, add hexadecyl mercaptan and azobisisobutyronitrile, stir and react under a nitrogen atmosphere, cool the product, remove the solvent by rotary evaporation, add ethanol and cool, collect the crystals by suction filtration, wash with ice-cold ethanol, and vacuum dry to obtain the composite antioxidant.

2. The CBC-containing olefin polymer film according to claim 1, characterized in that The additive is one or more of a plasticizer, a UV stabilizer, a matting agent, a biocide, an antioxidant, an antistatic agent, a fire retardant, a reinforcing agent, and a pigment.

3. The CBC-containing olefin polymer film according to claim 1, characterized in that In step (1), the molar ratio of melamine, 3,5-di-tert-butyl-4-hydroxybenzaldehyde and p-toluenesulfonic acid is 1:1-3:0.001-0.

01.

4. The CBC-containing olefin polymer film according to claim 1, characterized in that In step (1), the stirring reaction condition is 60-100° C. for 2-6 hours.

5. The CBC-containing olefin polymer film according to claim 1, characterized in that In step (2), the molar ratio of the intermediate, hexadecyl mercaptan and azobisisobutyronitrile is 1:1-3:0.001-0.

01.

6. The CBC-containing olefin polymer film according to claim 1, characterized in that In step (2), the stirring reaction conditions are 40-65° C. and 2-8 h.

7. Use of the CBC-containing olefin polymer film according to any one of claims 1 to 6 in a capacitor.

8. A method for preparing an olefin polymer film containing CBC as claimed in any one of claims 1 to 6, characterized in that: The method comprises the following steps: putting a propylene homopolymer, a cyclic block copolymer and an additive into a mixing device and mixing them evenly, feeding the mixture into an extruder, and plasticizing the mixture into a mixed melt through seven-stage heating and stabilizing pressure in the extruder to ensure that the raw materials are fully plasticized and blended, filtering the melt through two stages, metering and extruding the melt to a chill roller, and cooling the melt by the chill roller to obtain a thick sheet to be stretched; heating the melt in a preheating zone of a synchronous stretching oven, and transversely stretching the melt into a film to ensure that both the rigid CBC chain and the flexible PP chain have high molecular chain mobility; and winding the film after trimming, thickness measurement and corona treatment to obtain the CBC-containing olefin polymer film.

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