Reactive macromolecular dielectric enhancer, polypropylene composite material and preparation and application thereof

Abstract

The application discloses a reactive macromolecular dielectric reinforcing agent, a polypropylene composite material and preparation and application thereof. The application prepares an activated macromolecular dielectric reinforcing agent through a free radical polymerization reaction of an acrylamide type polar monomer, wherein 1,3-butadiene is used for end capping; then, the activated macromolecular dielectric reinforcing agent is reacted with ethylene to obtain a reactive macromolecular dielectric reinforcing agent. The application also adds the reactive macromolecular dielectric reinforcing agent into a polypropylene polymerization reaction to prepare a polypropylene composite material with a high dielectric constant through coordination polymerization. The application macromolecularizes an amide group, can obviously improve the compatibility of a polar group amide group and non-polar polypropylene, solves the problems of precipitation, dispersion and uneven dispersion of the polar group amide group in a polypropylene matrix, endows the polypropylene composite material with the characteristics of high efficiency and durability of dielectric properties, and is suitable for being used in related products, such as thin film capacitors and lithium battery separators, which need a high dielectric constant.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, specifically to a reactive macromolecular dielectric enhancer, a polypropylene composite material, and their preparation and application. Background Technology

[0002] Polypropylene (PP) is a polymer formed by the addition polymerization of propylene or propylene with a small amount of ethylene. PP possesses advantages such as stable electrical properties, good temperature resistance, good mechanical properties, and low dielectric loss, making it widely used in the field of capacitor films. An ideal capacitor film material should possess the following characteristics: high dielectric constant (high energy density), high breakdown strength, high temperature resistance (>150℃), low dielectric loss (low heat generation), and excellent processability. However, due to the unique hydrocarbon structure of PP, its dielectric constant is relatively low, resulting in a correspondingly low energy density for capacitor films. Therefore, improving the dielectric constant of PP resin to achieve higher energy density in capacitor film products is one of the research hotspots in the PP field.

[0003] CN202010199051.7 uses polyvinylidene fluoride-hexafluoropropylene as raw material to prepare polyvinylidene fluoride-hexafluoropropylene / polypropylene composite material by melt blending. The polyvinylidene fluoride-hexafluoropropylene in the composite material has good compatibility and dispersibility with the polypropylene matrix. The 5-30 micrometer film made by further hot pressing or co-extrusion has the advantages of high dielectric constant and good processing performance.

[0004] CN201310708192.7 describes a composite material prepared using isotactic polypropylene, low-density polyethylene, sodium borate, methyltriacetoxysilane, sodium silicate, ethylenediaminetetraacetic acid, sodium glycocholate, etc., as raw materials for composite plastic metallized films for capacitors. This material addresses the problems of low dielectric constant, poor heat resistance, poor film-forming properties, and low mechanical strength of general film capacitor dielectrics.

[0005] CN202010199039.6 describes a polypropylene composite dielectric material obtained by melt blending polypropylene and barium titanate nanoparticles with a core-shell structure (barium titanate core and polymethyl methacrylate shell). The resulting high-energy-storage polypropylene-based composite dielectric material has the characteristics of low cost, low density, good toughness, easy film stretching, high energy storage and high charge-discharge efficiency.

[0006] CN201711382194.6 describes the melt blending of pure polypropylene, maleic anhydride-grafted polypropylene, and nano-zirconia with KH570 silane coupling treatment on the surface in a certain proportion, and the preparation of composite films using this composite material. The dielectric constant and breakdown field strength of the obtained ternary composite medium are significantly improved simultaneously.

[0007] CN202010506800.6 describes the preparation of modified polypropylene films by adding SiO2 / BaSO4 composite microparticles with a mesh size of 80-120 mesh, and modifying a mixed system of polyacrylic acid resin, epoxy resin, and butene-maleic anhydride copolymer microspheres in a weight ratio of 1:1:1-3 to obtain a modified polypropylene medium with high dielectric constant and better comprehensive performance.

[0008] CN201811454400.4 discloses a polypropylene modified material that combines flame retardancy, thermal conductivity, and high dielectric constant, and its preparation method. It introduces hexagonal boron nitride nanosheets into polypropylene, which can significantly increase the thermal conductivity and dielectric constant of the polypropylene modified material without changing its insulation properties, and without causing a loss of the mechanical properties of the polypropylene modified material.

[0009] CN201810972224.7 discloses a high dielectric constant polypropylene / ceramic composite material for membrane capacitors, comprising, by mass percentage, 90.0-95.0% polypropylene and 5.0-10.0% high dielectric constant ceramic powder composed of one or more of barium titanate, strontium titanate, and barium strontium titanate. This overcomes the significant problems in existing membrane capacitor composite materials, such as complex composition, low breakdown field strength, and inability to be cast into films.

[0010] CN202010832384.9 discloses a high dielectric constant polypropylene composite material and its preparation method. The method uses inexpensive C30-45 alkyl-modified propyl silsesquioxane and inorganic fillers, along with a simple and easy composite method, to modify polypropylene. Compared with ordinary polypropylene, this method improves the dielectric properties of polypropylene at a lower cost without affecting its inherent excellent mechanical properties, processing properties, thermal properties, and crystallization properties.

[0011] In the aforementioned prior art, although the addition of either inorganic or organic materials can increase the dielectric constant, it will significantly increase the dielectric loss of the polypropylene composite. After the capacitor film is made, the breakdown strength will decrease significantly. Moreover, the uneven dispersion of inorganic materials will make the film processing more difficult. Summary of the Invention

[0012] One objective of this invention is to provide a reactive macromolecular dielectric enhancer and its preparation method; another objective of this invention is to provide a polypropylene composite material, its preparation method, and its application.

[0013] To achieve the above objectives, the present invention adopts the following technical solution:

[0014] This invention provides a method for preparing a reactive macromolecular dielectric enhancer, wherein the preparation method includes the following steps:

[0015] An activated macromolecular dielectric enhancer was prepared by free radical polymerization of acrylamide-based polar monomers as shown in Formula (I), wherein 1,3-butadiene was used for end capping.

[0016] The reactive macromolecular dielectric enhancer was obtained by reacting the obtained activated macromolecular dielectric enhancer with ethylene.

[0017]

[0018] Wherein, R is selected from hydrogen and C1-C6 alkyl groups; the number average molecular weight (Mn) of the activated macromolecular dielectric enhancer is 7000-15000;

[0019] Based on 100 parts by mass of the acrylamide polar monomer, the amount of 1,3-butadiene is 2.0 to 4.0 parts; the amount of ethylene is used to maintain a reaction pressure of 35 to 45 MPa.

[0020] The structure of the prepared activated macromolecular dielectric enhancer can be schematically represented by the following formula (II):

[0021]

[0022] Where R is defined as above, and h is the number of repeating units, h≥1.

[0023] The structure of the prepared reactive macromolecular dielectric enhancer can be schematically represented by the following formula (III):

[0024]

[0025] Where R is defined as above, m and n are the number of repeating units of the corresponding chain segment, m = 10 to 30, n = 5 to 20.

[0026] According to some specific embodiments of the present invention, wherein R is hydrogen or methyl.

[0027] According to some specific embodiments of the present invention, the acrylamide polar monomer is selected from one of acrylamide, methacrylamide, N-ethylacrylamide, N-isopropylacrylamide, N-tert-butylacrylamide, N-butylacrylamide and N-isopentylacrylamide.

[0028] According to some specific embodiments of the present invention, the acrylamide polar monomer is acrylamide or methacrylamide.

[0029] According to some specific embodiments of the present invention, the acrylamide polar monomer is methacrylamide.

[0030] According to some specific embodiments of the present invention, wherein, based on 100 parts by mass of the acrylamide polar monomer, 0.3 to 0.5 parts by molecular weight regulator and 0.05 to 0.3 parts by initiator are also added during the free radical polymerization reaction of the acrylamide polar monomer.

[0031] The molecular weight regulator is a polar organic compound that undergoes a chain transfer reaction in the polymerization system. The molecular weight of the resulting activated macromolecular dielectric enhancer is controlled by adjusting its dosage. The molecular weight regulator is preferably one of tert-decyl thiols, tert-dodecyl thiols, tert-tetradecyl thiols, and tert-hexadecyl thiols; more preferably tert-dodecyl thiols.

[0032] According to some specific embodiments of the present invention, the initiator is an organic peroxide.

[0033] According to some specific embodiments of the present invention, the initiator is selected from one or more combinations of diacetyl peroxide, diisobutyryl peroxide, cumene hydroperoxide, diisobutyryl peroxide and dibenzoyl peroxide.

[0034] According to some specific embodiments of the present invention, the initiator is dicumyl peroxide.

[0035] According to some specific embodiments of the present invention, the free radical polymerization reaction is carried out in a solvent under a protective gas atmosphere; the reaction temperature of the free radical polymerization reaction is 70–85°C, and the time is 4.0–6.0 h. The protective gas is, for example, nitrogen or a rare gas, such as helium or argon.

[0036] According to some specific embodiments of the present invention, the preparation process of the activated macromolecular dielectric enhancer includes: mixing the acrylamide polar monomer, molecular weight regulator and solvent in a protective atmosphere, then adding an initiator at 70-85°C, reacting for 4.0-6.0 h, and then adding 1,3-butadiene for end-capping to obtain the activated macromolecular dielectric enhancer.

[0037] According to some specific embodiments of the present invention, the reaction of the activated macromolecular dielectric enhancer and ethylene specifically includes the following process: in a protective atmosphere, a nickel-based complex catalyst, an alkylaluminoxane co-catalyst and the activated macromolecular dielectric enhancer are mixed with a solvent, and ethylene is introduced to carry out the reaction to obtain the reactive macromolecular dielectric enhancer.

[0038] Based on 1 part by mass of the nickel-based complex catalyst, the amount of the activated macromolecular dielectric enhancer is 2.5 to 4.5 parts, and the amount of the alkylaluminoxane co-catalyst is 90 to 100 parts.

[0039] According to some specific embodiments of the present invention, the reaction of the activated macromolecular dielectric enhancer and ethylene specifically includes the following process: In a protective atmosphere, 700-800 parts of solvent are heated to 110-130°C in a reaction vessel, and 90-100 parts of alkylaluminoxane co-catalyst are added dropwise while stirring at 700-900 rpm, with stirring continuing for 40-60 min; subsequently, 2.5-4.5 parts of the activated macromolecular dielectric enhancer and 400-600 parts of solvent are mixed and stirred to dissolve for 30-50 min until completely dissolved, and then added together with 1 part of nickel-based complex catalyst to the reaction vessel. Ethylene is then introduced, and the reaction is maintained at a pressure of 35-45 MPa for 8.0-10.0 h; after the reaction is completed, the reactant is obtained by centrifugation and drying. Preferably, the drying temperature is 50-60°C. Preferably, the reaction vessel is a high-pressure reactor.

[0040] According to some specific embodiments of the present invention, the nickel-based complex catalyst is selected from one of (1-naphthyl)[8-(diphenylphosphino)quinoline]nickel chloride, trans-phenyl bromide (di(triphenylphosphine))nickel, and 2,5-dicarboxypyrrole nickel dibromide.

[0041] According to some specific embodiments of the present invention, the nickel-based complex catalyst is nickel chloride (1-naphthyl)[8-(diphenylphosphino)quinoline].

[0042] According to some specific embodiments of the present invention, the alkylaluminoxane cocatalyst is methylaluminoxane (MAO) or ethylaluminoxane (EAO).

[0043] According to some specific embodiments of the present invention, the alkylaluminoxane cocatalyst is methylaluminoxane.

[0044] According to some specific embodiments of the present invention, the solvent is a hydrocarbon solvent.

[0045] According to some specific embodiments of the present invention, the solvent is selected from one or more combinations of pentane, hexane, octane, heptane, cyclohexane, benzene, toluene, xylene and ethylbenzene.

[0046] According to some specific embodiments of the present invention, the protective gas atmosphere is achieved by purging the reaction vessel with protective gas 2 to 3 times. Alternatively, other commonly used methods for creating a protective gas atmosphere can also be used.

[0047] Another aspect of the present invention provides a reactive macromolecular dielectric enhancer, wherein the reactive macromolecular dielectric enhancer is prepared according to the preparation method described above in the present invention.

[0048] According to some specific embodiments of the present invention, the structure of the reactive macromolecular dielectric enhancer can be schematically represented as formula (III):

[0049]

[0050] Wherein, R is selected from hydrogen and C1 to C6 alkyl groups; m and n are the number of repeating units in the corresponding chain segment, m = 10 to 30, n = 5 to 20.

[0051] According to some specific embodiments of the present invention, R is hydrogen or methyl.

[0052] In another aspect, the present invention provides a method for preparing a polypropylene composite material, wherein the method comprises preparing the polypropylene composite material by means of a polymerization reaction using a reactive macromolecular dielectric reinforcing agent prepared in the present invention and propylene as raw materials.

[0053] According to some specific embodiments of the present invention, the preparation method includes preparing the polypropylene composite material by polymerization reaction using the reactive macromolecular dielectric enhancer and propylene as raw materials in the presence of a supported Ziegler-Natta catalyst; the mass of the supported Ziegler-Natta catalyst is 1 part, the mass of the reactive macromolecular dielectric enhancer is 7 to 11 parts, and the amount of propylene is used to maintain a reaction pressure of 20 to 30 MPa.

[0054] According to some specific embodiments of the present invention, the polymerization reaction of the reactive macromolecular dielectric enhancer and propylene is carried out at a temperature of 75-85°C and for a reaction time of 3.0-5.0 h.

[0055] According to some specific embodiments of the present invention, the preparation method includes:

[0056] Under a protective atmosphere, a supported Ziegler-Natta catalyst and a reactive macromolecular dielectric enhancer are mixed, and propylene and hydrogen are introduced, wherein the volume concentration of hydrogen is 200-2000 ppm. The polymerization reaction is carried out at 75-85°C and 20-30 MPa for 3.0-5.0 h to obtain the polypropylene composite material.

[0057] According to some specific embodiments of the present invention, the protective gas atmosphere is achieved by purging the reaction vessel with protective gas 3 to 5 times. Alternatively, other commonly used methods for creating a protective gas atmosphere can also be used.

[0058] According to some specific embodiments of the present invention, the preparation method includes:

[0059] Based on 1 part by mass of the supported Ziegler-Natta catalyst, the high-pressure reactor is heated and evacuated to remove air and water. The reactor is then purged with protective gas 3 to 5 times. Then, 1 part of the supported Ziegler-Natta solid catalyst and 7 to 11 parts of the reactive macromolecular dielectric enhancer are added. Propylene and a small amount of hydrogen gas are then introduced, with a hydrogen volume concentration of 200 to 2000 ppm. The pressure is maintained at 20 to 30 MPa and the reactor temperature is maintained at 75 to 85 °C to start polymerization. After 3.0 to 5.0 h of reaction, the unreacted gas is discharged to obtain the polypropylene composite material powder.

[0060] The components of the supported Ziegler-Natta catalysts described in this invention are generally known to those skilled in the art. Typically, the Ziegler-Natta main catalyst comprises a titanium compound and an optional internal electron donor. An internal electron donor refers to a compound that is part of the solid Ziegler-Natta main catalyst. The titanium compound and the optional internal electron donor are preferably supported on a solid magnesium compound support.

[0061] According to some specific embodiments of the present invention, the supported Ziegler-Natta catalyst comprises a main catalyst and an organometallic co-catalyst; the main catalyst is a combination of one or more catalysts selected from ethyl benzoate, phthalic acid monoester or diester, monoether, diether or succinate as internal electron donors, with MgCl2 as support and TiCl4 as active center; the organometallic co-catalyst is composed of alkyl aluminum compounds.

[0062] According to some specific embodiments of the present invention, the alkylaluminum compound is selected from one or more combinations of trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, diethylaluminum chloride, and ethylaluminum dichloride.

[0063] According to some specific embodiments of the present invention, the alkylaluminum compound is triethylaluminum.

[0064] According to some specific embodiments of the present invention, the internal electron donor is diisobutyl phthalate.

[0065] According to some specific embodiments of the present invention, the content of active transition metal element (Ti) in the main catalyst of the present invention is 1.85 to 3.56 wt% based on 100% of the total mass of the main catalyst, and the organometallic co-catalyst alkylaluminum is added in a ratio of Al / Ti (molar) = 50 to 80.

[0066] In the preparation method of the polypropylene composite material of the present invention, the amount of hydrogen added is well known to those skilled in the art and conforms to the conventional addition range during propylene polymerization in the prior art. The present invention does not impose any particular limitation.

[0067] In the preparation method of the polypropylene composite material of the present invention, the reaction vessel used can be a loop reactor or a batch reactor, preferably a batch reactor.

[0068] The polymerization method for the polypropylene composite material of the present invention can utilize known liquid-phase bulk polymerization or gas-phase polymerization, with liquid-phase bulk polymerization being preferred. This method operates in a liquid phase or via a mixed liquid-gas technique. These methods are well known to those skilled in the art.

[0069] In another aspect, the present invention provides a polypropylene composite material obtained by any of the above preparation methods.

[0070] According to some specific embodiments of the present invention, the dielectric constant of the polypropylene composite material is ≥3.8.

[0071] According to some specific embodiments of the present invention, the dielectric constant of the polypropylene composite material is 3.8 to 4.2.

[0072] According to some specific embodiments of the present invention, the dielectric loss of the polypropylene composite material is less than 3tgδ×10. 4 .

[0073] According to some specific embodiments of the present invention, the dielectric loss of the polypropylene composite material is less than 2.8 tgδ × 10 4 .

[0074] According to some specific embodiments of the present invention, the dielectric loss of the polypropylene composite material is (2.53~2.75)tgδ×10 4 .

[0075] According to some specific embodiments of the present invention, the melt mass flow rate (MFR) of the polypropylene composite material is (5.4–7.3) g / 10 min.

[0076] The present invention also provides the application of the polypropylene composite material in the preparation of thin-film capacitors or lithium battery separators.

[0077] This invention first synthesizes an activated macromolecular dielectric enhancer with strongly polar groups using acrylamide-based polar monomers and 1,3-butadiene. Second, in the presence of a nickel-based complex catalyst, a reactive macromolecular dielectric enhancer with free radical reactivity is prepared from the reactive monomer ethylene and the activated macromolecular dielectric enhancer. Finally, the reactive macromolecular dielectric enhancer is added to the polypropylene polymerization reaction, and a polypropylene composite material with a high dielectric constant is prepared through coordination polymerization. This invention macromolecularizes the amide groups, significantly improving the compatibility between polar amide groups and non-polar polypropylene, solving the problems of precipitation, dispersion, and uneven dispersion of polar amide groups in the polypropylene matrix, and endowing the polypropylene composite material with high efficiency and durability of dielectric properties. It is suitable for applications requiring high dielectric constants, such as thin-film capacitors and lithium-ion battery separators. This method is energy-saving, environmentally friendly, has low modification costs, and produces a high dielectric constant.

[0078] The beneficial effects of this invention include:

[0079] 1) This invention enables the macromolecularization of amide groups, which can significantly improve the compatibility between polar amide groups and non-polar polypropylene, and solve the problems of precipitation, dispersion and uneven dispersion of polar amide groups in polypropylene matrix.

[0080] 2) The polypropylene composite material prepared by this invention has the characteristics of high efficiency and durability in dielectric properties, and is suitable for use in related products that require high dielectric constant, such as thin film capacitors and lithium battery separators.

[0081] 3) The preparation method of the polypropylene composite material of the present invention is simple, energy-saving and environmentally friendly, and low in cost. The polypropylene composite material has stable performance and high dielectric constant, making it suitable for industrial production. Detailed Implementation

[0082] To more clearly illustrate the present invention, the following description, in conjunction with preferred embodiments, further clarifies the invention. Those skilled in the art should understand that the specific descriptions below are illustrative rather than restrictive, and should not be construed as limiting the scope of protection of the present invention.

[0083] All numerical specifications in this invention (e.g., temperature, time, concentration, and weight, including ranges for each) are generally approximate values ​​that may be changed (+) or (-) in increments of 0.1 or 1.0. All numerical specifications are to be understood as being preceded by the term "about".

[0084] (1) Source of raw materials:

[0085] Ethylene, 99% purity, from Lanzhou Petrochemical Company of China National Petroleum Corporation;

[0086] Propylene, 99% purity, from Lanzhou Petrochemical Company of China National Petroleum Corporation;

[0087] Methacrylamide, Ningbo Yingrunde Chemical Co., Ltd.;

[0088] Dicumyl peroxide (DCP), Lanzhou Additives Factory;

[0089] Diisobutyl phthalate, Nanjing Chemical Reagent Co., Ltd.;

[0090] All other reagents are commercially available industrial products.

[0091] (2) Analysis and testing methods:

[0092] Preparation method of polypropylene film samples:

[0093] Polypropylene composite granules were placed in a vacuum hot press for hot pressing to obtain a polypropylene film with a high dielectric constant. The hot pressing conditions were: 150℃, 10MPa pressure, and 2min holding time.

[0094] Dielectric testing:

[0095] To test the polypropylene film sample, gold was first sputtered onto the sample surface (gold ion sputtering), with an electrode diameter of 30 mm. The test was conducted at room temperature (25℃) and in the frequency range of 0.1 to 105 Hz to obtain the dielectric constant and dielectric loss of the sample.

[0096] Determination of molecular weight and its distribution:

[0097] The determination was performed using a 2414 gel permeation chromatography (GPC) system. A polystyrene standard was used as the calibration curve. The mobile phase was tetrahydrofuran, the column temperature was 40℃, the sample concentration was 1 mg / mL, the injection volume was 50 μL, the elution time was 40 min, and the flow rate was 1 mL / min. -1 .

[0098] Determination of melt mass flow rate (MFR):

[0099] The method in standard GB / T 3682-2000 shall be followed.

[0100] Weather resistance test:

[0101] Performed according to SAE J2527-2004, with an illumination amplitude of 0.55 W / m. 2 The test lasted for 1000 hours.

[0102] Example 1

[0103] This embodiment prepares a reactive macromolecular dielectric enhancer and uses it to prepare a polypropylene composite material.

[0104] (1) Preparation of reactive macromolecular dielectric enhancers:

[0105] a. Preparation of activated macromolecular dielectric enhancers:

[0106] First, in a 5L stainless steel reactor with a jacket, nitrogen was purged three times. Then, 1000g of cyclohexane, 500g of methacrylamide, and 1.5g of tert-dodecyl mercaptan were added to the reactor in sequence. The mixture was stirred and heated until the reactor temperature reached 70℃. Then, 0.25g of DCP was added and the reaction was carried out for 4.0h. Then, 10g of 1,3-butadiene was added to the polymerization reactor for end-capping and the reaction was carried out for 30min until no free monomers were present. After the reaction was completed, the mixture was washed with hexane and dried at 65℃ to obtain the activated macromolecular dielectric enhancer.

[0107] The number-average molecular weight (Mn) of the activated macromolecular dielectric enhancer is 7000.

[0108] b. Preparation of reactive macromolecular dielectric enhancers:

[0109] First, nitrogen was purged three times in a 15L high-pressure reactor. 1400g of cyclohexane was added, and the temperature was raised to 110℃. Then, 180g of methylaluminoxane co-catalyst was added dropwise at a stirring speed of 700rpm. Stirring continued for 40min under nitrogen protection. Subsequently, 5g of activated macromolecular dielectric enhancer and 800g of cyclohexane were mixed and stirred for 30min until completely dissolved. Then, 2g of (1-naphthyl)[8-(diphenylphosphino)quinoline]nickel chloride was added to the high-pressure reactor. Ethylene was introduced at this time, and the pressure was maintained at 35MPa. The reaction was carried out for 8.0h. After the reaction was completed, the reactive macromolecular dielectric enhancer was obtained by centrifugation and drying at 50℃.

[0110] (2) Preparation of polypropylene composite materials:

[0111] A 15L high-pressure reactor was heated and evacuated to remove air and water. The reactor was then purged with nitrogen three times. 2g of a MgCl2-supported Ziegler-Natta solid catalyst (composed of TiCl4, triethylaluminum, and diisobutyl phthalate) with an Al / Ti (molar ratio) of 50.3 and 14g of a reactive macromolecular dielectric enhancer were then introduced. Propylene and 1000ppm hydrogen were then introduced, maintaining a pressure of 20MPa and a reactor temperature of 75℃ to initiate polymerization. After 3.0 hours of reaction, unreacted gases were discharged to obtain polypropylene composite powder.

[0112] Sampling and analysis: Polypropylene composite powder was prepared into thin film samples according to standard methods and then subjected to dielectric tests. The test performance is shown in Table 1.

[0113] The melt mass flow rate (MFR) of the polypropylene composite powder is 7.3 g / 10 min.

[0114] Example 2

[0115] This embodiment prepares a reactive macromolecular dielectric enhancer and uses it to prepare a polypropylene composite material.

[0116] (1) Preparation of reactive macromolecular dielectric enhancers:

[0117] a. Preparation of activated macromolecular dielectric enhancers:

[0118] First, in a 5L stainless steel reactor with a jacket, nitrogen was purged three times. Then, 1100g of cyclohexane, 500g of methacrylamide, and 1.7g of tert-dodecyl mercaptan were added to the reactor in sequence. The mixture was stirred and heated until the reactor temperature reached 72℃. Then, 0.30g of DCP was added and the reaction was carried out for 4.5h. Then, 12g of 1,3-butadiene was added to the polymerization reactor for end-capping and the reaction was carried out for 35min until no free monomers were present. After the reaction was completed, the mixture was washed with hexane and dried at 67℃ to obtain the activated macromolecular dielectric enhancer.

[0119] The number-average molecular weight (Mn) of the activated macromolecular dielectric enhancer is 9000.

[0120] b. Preparation of reactive macromolecular dielectric enhancers:

[0121] First, nitrogen was purged three times in a 15L high-pressure reactor. Then, 1450g of cyclohexane was added, and the temperature was raised to 115℃. 183g of methylaluminoxane co-catalyst was then added dropwise at a stirring speed of 750rpm. Stirring continued for 42min under nitrogen protection. Subsequently, 6g of activated macromolecular dielectric enhancer and 900g of cyclohexane were mixed and stirred for 35min until completely dissolved. Then, 2g of (1-naphthyl)[8-(diphenylphosphino)quinoline]nickel chloride was added to the high-pressure reactor. Ethylene was introduced at this time, and the pressure was maintained at 37MPa. The reaction was carried out for 8.4h. After the reaction was completed, the reactive macromolecular dielectric enhancer was obtained by centrifugation and drying at 52℃.

[0122] (2) Preparation of polypropylene composite materials:

[0123] A 15L high-pressure reactor was heated and evacuated to remove air and water. The reactor was then purged with nitrogen three times. 1.88g of a MgCl2-supported Ziegler-Natta solid catalyst (composed of TiCl4, triethylaluminum, and diisobutyl phthalate) with an Al / Ti (molar) ratio of 55.6 and 15g of a reactive macromolecular dielectric enhancer were then introduced. Propylene and 800ppm of hydrogen were then introduced, maintaining a pressure of 22MPa and a reactor temperature of 77℃ to initiate polymerization. After 3.5 hours of reaction, unreacted gases were discharged to obtain polypropylene composite powder.

[0124] Sampling and analysis: Polypropylene composite powder was prepared into thin film samples according to standard methods and then subjected to dielectric tests. The test performance is shown in Table 1.

[0125] The melt mass flow rate (MFR) of the polypropylene composite powder is 7.1 g / 10 min.

[0126] Example 3

[0127] This embodiment prepares a reactive macromolecular dielectric enhancer and uses it to prepare a polypropylene composite material.

[0128] (1) Preparation of reactive macromolecular dielectric enhancers:

[0129] a. Preparation of activated macromolecular dielectric enhancers:

[0130] First, in a 5L stainless steel reactor with a jacket, nitrogen was purged four times. Then, 1300g of cyclohexane, 500g of methacrylamide, and 2.1g of tert-dodecyl mercaptan were added to the reactor in sequence. The mixture was stirred and heated until the reactor temperature reached 77℃. Then, 0.41g of DCP was added and the reaction was carried out for 5.0h. Then, 15g of 1,3-butadiene was added to the polymerization reactor for end-capping and the reaction was carried out for 42min until no free monomers were present. After the reaction was completed, the mixture was washed with hexane and dried at 69℃ to obtain the activated macromolecular dielectric enhancer.

[0131] The number-average molecular weight (Mn) of the activated macromolecular dielectric enhancer is 10,000.

[0132] b. Preparation of reactive macromolecular dielectric enhancers:

[0133] First, nitrogen was purged four times in a 15L high-pressure reactor. Then, 1530g of cyclohexane was added, and the temperature was raised to 120℃. 190g of methylaluminoxane co-catalyst was then added dropwise at a stirring speed of 820rpm. Stirring continued for 50min under nitrogen protection. Subsequently, 7.5g of activated macromolecular dielectric enhancer and 1000g of cyclohexane were mixed and stirred for 41min until completely dissolved. Then, 2g of (1-naphthyl)[8-(diphenylphosphino)quinoline]nickel chloride was added to the high-pressure reactor. Ethylene was introduced at this time, and the pressure was maintained at 40MPa. The reaction was carried out for 9.0h. After the reaction was completed, the reactive macromolecular dielectric enhancer was obtained by centrifugation and drying at 54℃.

[0134] (2) Preparation of polypropylene composite materials:

[0135] A 15L high-pressure reactor was heated and evacuated to remove air and water. The reactor was then purged with nitrogen four times. 2.11g of a MgCl2-supported Ziegler-Natta solid catalyst (composed of TiCl4, triethylaluminum, and diisobutyl phthalate) with an Al / Ti (molar ratio) of 63.2 and 19g of a reactive macromolecular dielectric enhancer were then introduced. Propylene and 1200ppm of hydrogen were then introduced, maintaining a pressure of 25MPa and a reactor temperature of 80℃ to initiate polymerization. After 4.0h of reaction, unreacted gases were discharged to obtain polypropylene composite powder.

[0136] Sampling and analysis: Polypropylene composite powder was prepared into thin film samples according to standard methods and then subjected to dielectric tests. The test performance is shown in Table 1.

[0137] The melt mass flow rate (MFR) of the polypropylene composite powder is 6.5 g / 10 min.

[0138] Example 4

[0139] This embodiment prepares a reactive macromolecular dielectric enhancer and uses it to prepare a polypropylene composite material.

[0140] (1) Preparation of reactive macromolecular dielectric enhancers:

[0141] a. Preparation of activated macromolecular dielectric enhancers:

[0142] First, in a 5L stainless steel reactor with a jacket, nitrogen was purged four times. Then, 1400g of cyclohexane, 500g of methacrylamide, and 2.3g of tert-dodecyl mercaptan were added to the reactor in sequence. The mixture was stirred and heated until the reactor temperature reached 80℃. Then, 0.52g of DCP was added and the reaction was carried out for 5.3h. Then, 17g of 1,3-butadiene was added to the polymerization reactor for end-capping and the reaction was carried out for 45min until no free monomers were present. After the reaction was completed, the mixture was washed with hexane and dried at 71℃ to obtain the activated macromolecular dielectric enhancer.

[0143] The number-average molecular weight (Mn) of the activated macromolecular dielectric enhancer is 12000.

[0144] b. Preparation of reactive macromolecular dielectric enhancers:

[0145] First, nitrogen was purged four times in a 15L high-pressure reactor. Then, 1550g of cyclohexane was added, and the temperature was raised to 124℃. 194g of methylaluminoxane co-catalyst was then added dropwise at a stirring speed of 850rpm. Stirring continued for 53min under inert gas protection. Subsequently, 8.0g of activated macromolecular dielectric enhancer and 1100g of cyclohexane were mixed and stirred for 45min until completely dissolved. Then, 2g of trans-bromophenyl(di(triphenylphosphine))nickel was added to the high-pressure reactor. Ethylene was introduced at this time, and the pressure was maintained at 42MPa. The reaction was carried out for 9.2h. After the reaction was completed, the reactive macromolecular dielectric enhancer was obtained by centrifugation and drying at 56℃.

[0146] (2) Preparation of polypropylene composite materials:

[0147] A 15L high-pressure reactor was heated and evacuated to remove air and water. The reactor was then purged with nitrogen four times. 2.4g of a MgCl2-supported Ziegler-Natta solid catalyst (composed of TiCl4, diethylaluminum chloride, and ethyl benzoate) with an Al / Ti (molar ratio) of 70.5 and 20g of a reactive macromolecular dielectric enhancer were then introduced. Propylene and 500ppm of hydrogen were then introduced, maintaining a pressure of 26MPa and a reactor temperature of 81℃ to initiate polymerization. After 4.5 hours of reaction, unreacted gases were discharged to obtain polypropylene composite powder.

[0148] Sampling and analysis: Polypropylene composite powder was prepared into thin film samples according to standard methods and then subjected to dielectric tests. The test performance is shown in Table 1.

[0149] The melt mass flow rate (MFR) of the polypropylene composite material is 6.1 g / 10 min.

[0150] Example 5

[0151] This embodiment prepares a reactive macromolecular dielectric enhancer and uses it to prepare a polypropylene composite material.

[0152] (1) Preparation of reactive macromolecular dielectric enhancers:

[0153] a. Preparation of activated macromolecular dielectric enhancers:

[0154] First, in a 5L stainless steel reactor with a jacket, nitrogen was purged five times. Then, 1450g of cyclohexane, 500g of acrylamide, and 2.4g of tert-dodecyl mercaptan were added to the reactor in sequence. The mixture was stirred and heated until the reactor temperature reached 83℃. Then, 0.65g of DCP was added and the reaction was carried out for 5.5h. Then, 19g of 1,3-butadiene was added to the polymerization reactor for end-capping and the reaction was carried out for 48min until no free monomers were present. After the reaction was completed, the mixture was washed with octane and dried at 73℃ to obtain the activated macromolecular dielectric enhancer.

[0155] The number-average molecular weight (Mn) of the activated macromolecular dielectric enhancer is 13,000.

[0156] b. Preparation of reactive macromolecular dielectric enhancers:

[0157] First, nitrogen was purged five times in a 15L high-pressure reactor. Then, 1580g of cyclohexane was added, and the temperature was raised to 126℃. 197g of ethylaluminoxane co-catalyst was then added dropwise at a stirring speed of 870rpm, and stirring was continued for 57min under nitrogen protection. Subsequently, 8.5g of activated macromolecular dielectric enhancer and 1150g of cyclohexane were mixed and stirred for 48min until completely dissolved. Then, 2g of trans-bromophenyl(di(triphenylphosphine))nickel was added to the high-pressure reactor. Ethylene was introduced at this time, and the pressure was maintained at 44MPa. The reaction was carried out for 9.6h. After the reaction was completed, the reactive macromolecular dielectric enhancer was obtained by centrifugation and drying at 58℃.

[0158] (2) Preparation of polypropylene composite materials:

[0159] A 15L high-pressure reactor was heated and evacuated to remove air and water. The reactor was then purged with nitrogen five times. 2.6g of a MgCl2-supported Ziegler-Natta solid catalyst (composed of TiCl4, diethylaluminum chloride, and ethyl benzoate) with an Al / Ti (molar ratio) of 76.2 and 21g of a reactive macromolecular dielectric enhancer were then introduced. Propylene and 200ppm of hydrogen were then introduced, maintaining a pressure of 28MPa and a reactor temperature of 83℃ to initiate polymerization. After 4.8 hours of reaction, unreacted gases were discharged to obtain polypropylene composite powder.

[0160] Sampling and analysis: Polypropylene composite powder was prepared into thin film samples according to standard methods and then subjected to dielectric tests. The test performance is shown in Table 1.

[0161] The melt mass flow rate (MFR) of the polypropylene composite powder is 5.8 g / 10 min.

[0162] Example 6

[0163] This embodiment prepares a reactive macromolecular dielectric enhancer and uses it to prepare a polypropylene composite material.

[0164] (1) Preparation of reactive macromolecular dielectric enhancers:

[0165] a. Preparation of activated macromolecular dielectric enhancers:

[0166] First, in a 5L stainless steel reactor with a jacket, nitrogen gas was purged five times. Then, 1500g of cyclohexane, 500g of acrylamide, and 2.5g of tert-dodecyl mercaptan were added to the reactor in sequence. The mixture was stirred and heated until the reactor temperature reached 85℃. Then, 0.85g of DCP was added and the reaction was carried out for 6.0h. Then, 20g of 1,3-butadiene was added to the polymerization reactor for end-capping and the reaction was carried out for 50min until no free monomers were present. After the reaction was completed, the mixture was washed with octane and dried at 75℃ to obtain the activated macromolecular dielectric enhancer.

[0167] The number-average molecular weight (Mn) of the activated macromolecular dielectric enhancer is 15,000.

[0168] b. Preparation of reactive macromolecular dielectric enhancers:

[0169] First, nitrogen was purged five times in a 15L high-pressure reactor. 1600g of cyclohexane was added, and the temperature was raised to 130℃. Then, 200g of ethylaluminoxane co-catalyst was added dropwise at a stirring speed of 900rpm. Stirring continued for 60min under nitrogen protection. Subsequently, 9.0g of activated macromolecular dielectric enhancer and 1200g of cyclohexane were mixed and stirred for 50min until completely dissolved. Then, 2g of 2,5-dicarboxypyrrole nickel dibromide was added to the high-pressure reactor. Ethylene was introduced at this time, and the pressure was maintained at 45MPa. The reaction was carried out for 10h. After the reaction was completed, the reactive macromolecular dielectric enhancer was obtained by centrifugation and drying at 60℃.

[0170] (2) Preparation of polypropylene composite materials:

[0171] A 15L high-pressure reactor was heated and evacuated to remove air and water. The reactor was purged with nitrogen five times. Then, 2.2g of MgCl2-supported Ziegler-Natta solid catalyst (composed of TiCl4, trimethylaluminum, and 2,2-diphenyl-1,3-propanediol dimethyl ether) with an Al / Ti (molar ratio) of 80.0 and 22g of reactive macromolecular dielectric enhancer were added. Propylene and 2000ppm of hydrogen were then introduced, and the pressure was maintained at 30MPa and the reactor temperature at 85℃ to begin polymerization. After 5.0h of reaction, the unreacted gas was discharged to obtain polypropylene composite powder.

[0172] Sampling and analysis: Polypropylene composite powder was prepared into thin film samples according to standard methods and then subjected to dielectric tests. The test performance is shown in Table 1.

[0173] The melt mass flow rate (MFR) of the polypropylene composite powder is 5.4 g / 10 min.

[0174] Comparative Example 1

[0175] This comparative study prepared a reactive macromolecular dielectric enhancer a and used it to prepare polypropylene composite materials.

[0176] (1) Preparation of reactive macromolecular dielectric enhancers:

[0177] a. Preparation of activated macromolecular dielectric enhancers:

[0178] Other conditions are the same as in Example 1, except that 1,3-butadiene is not added during the preparation of the activated macromolecular dielectric enhancer, i.e.:

[0179] First, nitrogen gas was purged three times in a 5L stainless steel reactor with a jacket. Then, 1000g of cyclohexane, 500g of methacrylamide, and 1.5g of tert-dodecyl mercaptan were added to the reactor in sequence. The mixture was stirred and heated. When the reactor temperature reached 70℃, 0.25g of DCP was added and the reaction was carried out for 4.0h. After the reaction was completed, the mixture was washed and dried at 65℃ to obtain macromolecular dielectric enhancer a.

[0180] The number-average molecular weight Mn of the activated macromolecular dielectric enhancer a is 6900.

[0181] b. Preparation of reactive macromolecular dielectric enhancers:

[0182] Other conditions are the same as in Example 1, except that no activating macromolecular dielectric enhancer is added during the preparation of the reactive macromolecular dielectric enhancer; instead, macromolecular dielectric enhancer a is added in an amount of 5g, i.e.:

[0183] First, nitrogen was purged three times in a 15L high-pressure reactor. 1400g of cyclohexane was added, and the temperature was raised to 110℃. Then, 180g of methylaluminoxane co-catalyst was added dropwise at a stirring speed of 700rpm. Stirring continued for 40min under nitrogen protection. Subsequently, 5g of macromolecular dielectric enhancer a and 800g of cyclohexane were mixed and stirred for 30min until completely dissolved. Then, 2g of (1-naphthyl)[8-(diphenylphosphino)quinoline]nickel chloride was added to the high-pressure reactor. Ethylene was introduced at this time, and the pressure was maintained at 35MPa. The reaction was carried out for 8.0h. After the reaction was completed, the reactive macromolecular dielectric enhancer a was obtained by centrifugation and drying at 50℃.

[0184] (2) Preparation of polypropylene composite materials:

[0185] Other conditions are the same as in Example 1, except that reactive macromolecular dielectric reinforcing agents are not added during the preparation of the polypropylene composite material; instead, reactive macromolecular dielectric reinforcing agent a is added in an amount of 14g, i.e.:

[0186] A 15L high-pressure reactor was heated and evacuated to remove air and water. The reactor was then purged with nitrogen three times. 2g of a MgCl2-supported Ziegler-Natta solid catalyst (composed of TiCl4, triethylaluminum, and diisobutyl phthalate) with an Al / Ti (molar ratio) of 50.3 was added, along with 14g of reactive macromolecular dielectric enhancer a. Propylene and 1000ppm hydrogen were then introduced, maintaining a pressure of 20MPa and a reactor temperature of 75℃ to initiate polymerization. After 3.0 hours of reaction, unreacted gases were discharged to obtain polypropylene composite powder.

[0187] Sampling and analysis: Polypropylene composite powder was prepared into thin film samples according to standard methods and then subjected to dielectric tests. The test performance is shown in Table 1.

[0188] The melt mass flow rate (MFR) of the polypropylene composite powder is 8.3 g / 10 min.

[0189] Comparative Example 2

[0190] This comparative study prepared a reactive macromolecular dielectric enhancer b and used it to prepare polypropylene composite materials.

[0191] (1) Preparation of reactive macromolecular dielectric enhancers:

[0192] Other conditions are the same as in Example 2, except that no activating macromolecular dielectric enhancer is added during the preparation of the reactive macromolecular dielectric enhancer; only small molecule methacrylamide is added, and the amount added is 6g.

[0193] First, nitrogen was purged three times in a 15L high-pressure reactor. Then, 1450g of cyclohexane was added, and the temperature was raised to 115℃. 183g of methylaluminoxane co-catalyst was then added dropwise at a stirring speed of 750rpm. Stirring continued for 42min under inert gas protection. Subsequently, 6g of methacrylamide and 900g of cyclohexane were mixed and stirred for 35min until completely dissolved. Then, 2g of (1-naphthyl)[8-(diphenylphosphino)quinoline]nickel chloride was added to the high-pressure reactor. Ethylene was introduced at this time, and the pressure was maintained at 37MPa. The reaction was carried out for 8.4h. After the reaction was completed, the reactive macromolecular dielectric enhancer b was obtained by centrifugation and drying at 52℃.

[0194] (2) Preparation of polypropylene composite materials:

[0195] Other conditions are the same as in Example 2, except that reactive macromolecular dielectric reinforcing agents are not added during the preparation of the polypropylene composite material; instead, reactive macromolecular dielectric reinforcing agent b is added in an amount of 15g.

[0196] A 15L high-pressure reactor was heated and evacuated to remove air and water. The reactor was then purged with nitrogen three times. 1.88g of a MgCl2-supported Ziegler-Natta solid catalyst (composed of TiCl4, triethylaluminum, and diisobutyl phthalate) with an Al / Ti (molar) ratio of 55.6 and 15g of reactive macromolecular dielectric enhancer b were added. Propylene and 800ppm of hydrogen were then introduced, maintaining a pressure of 22MPa and a reactor temperature of 77℃ to initiate polymerization. After 3.5 hours of reaction, unreacted gases were discharged to obtain polypropylene composite powder.

[0197] Sampling and analysis: Polypropylene composite powder was prepared into thin film samples according to standard methods and then subjected to dielectric tests. The test performance is shown in Table 1.

[0198] The melt mass flow rate (MFR) of the polypropylene composite powder is 8.1 g / 10 min.

[0199] Comparative Example 3

[0200] This comparative study prepared a reactive macromolecular dielectric enhancer c and used it to prepare polypropylene composite materials.

[0201] (1) Preparation of reactive macromolecular dielectric enhancers:

[0202] a. Preparation of activated macromolecular dielectric enhancers:

[0203] Other conditions are the same as in Example 3, except that methyl methacrylate is added instead of methacrylamide during the preparation of the activated macromolecular dielectric enhancer, and the amount added is 500g.

[0204] First, in a 5L stainless steel reactor with a jacket, nitrogen was purged four times. Then, 1300g of cyclohexane, 500g of methyl methacrylate, and 2.1g of tert-dodecyl mercaptan were added to the reactor in sequence. The mixture was stirred and heated until the reactor temperature reached 77℃. Then, 0.41g of DCP was added and the reaction was carried out for 5.0h. Then, 15g of 1,3-butadiene was added to the polymerization reactor for end-capping and the reaction was carried out for 42min until no free monomers were present. After the reaction was completed, the mixture was washed and dried at 69℃ to obtain activated macromolecular dielectric enhancer b.

[0205] The number-average molecular weight Mn of the activated macromolecular dielectric enhancer b is 11000.

[0206] b. Preparation of reactive macromolecular dielectric enhancers:

[0207] Other conditions are the same as in Example 3, except that no activating macromolecular dielectric enhancer is added during the preparation of the reactive macromolecular dielectric enhancer; instead, macromolecular dielectric enhancer b is added in an amount of 7.5 g, i.e.:

[0208] First, nitrogen was purged four times in a 15L high-pressure reactor. 1530g of cyclohexane was added, and the temperature was raised to 120℃. Then, 190g of methylaluminoxane co-catalyst was added dropwise at a stirring speed of 820rpm. Stirring continued for 50min under nitrogen protection. Subsequently, 7.5g of activated macromolecular dielectric enhancer b and 1000g of cyclohexane were mixed and stirred for 41min until completely dissolved. Then, 2g of (1-naphthyl)[8-(diphenylphosphino)quinoline]nickel chloride was added to the high-pressure reactor. Ethylene was introduced at this time, and the pressure was maintained at 40MPa. The reaction was carried out for 9.0h. After the reaction was completed, the reactive macromolecular dielectric enhancer c was obtained by centrifugation and drying at 54℃.

[0209] (2) Preparation of polypropylene composite materials:

[0210] Other conditions are the same as in Example 3, except that reactive macromolecular dielectric reinforcing agents are not added during the preparation of the polypropylene composite material; instead, reactive macromolecular dielectric reinforcing agent c is added in an amount of 19g.

[0211] A 15L high-pressure reactor was heated and evacuated to remove air and water. The reactor was then purged with nitrogen four times. 2.11g of a MgCl2-supported Ziegler-Natta solid catalyst (composed of TiCl4, triethylaluminum, and diisobutyl phthalate) with an Al / Ti (molar ratio) of 63.2 and 19g of a reactive macromolecular dielectric enhancer (c) were added. Propylene and 1200ppm of hydrogen were then introduced, maintaining a pressure of 25MPa and a reactor temperature of 80℃ to initiate polymerization. After 4.0h of reaction, unreacted gases were discharged to obtain polypropylene composite powder.

[0212] Sampling and analysis: Polypropylene composite powder was prepared into thin film samples according to standard methods and then subjected to dielectric tests. The test performance is shown in Table 1.

[0213] The melt mass flow rate (MFR) of the polypropylene composite powder is 5.1 g / 10 min.

[0214] Comparative Example 4

[0215] This comparative study prepared a reactive macromolecular dielectric enhancer d and used it to prepare polypropylene composite materials.

[0216] (1) Preparation of reactive macromolecular dielectric enhancers:

[0217] a. Preparation of activated macromolecular dielectric enhancers:

[0218] Other conditions are the same as in Example 4, except that the amount of organic peroxide DCP added during the preparation of the activated macromolecular dielectric enhancer is 0.05 g, that is:

[0219] First, in a 5L stainless steel reactor with a jacket, nitrogen was purged four times. Then, 1400g of cyclohexane, 500g of methacrylamide, and 2.3g of tert-dodecyl mercaptan were added to the reactor in sequence. The mixture was stirred and heated until the reactor temperature reached 80℃. Then, 0.05g of DCP was added and the reaction was carried out for 5.3h. Then, 17g of 1,3-butadiene was added to the polymerization reactor for end-capping and the reaction was carried out for 45min until no free monomers were present. After the reaction was completed, the mixture was washed and dried at 71℃ to obtain activated macromolecular dielectric enhancer c.

[0220] The number-average molecular weight (Mn) of the activated macromolecular dielectric enhancer c is 4000.

[0221] b. Preparation of reactive macromolecular dielectric enhancers:

[0222] Other conditions are the same as in Example 4, except that no activating macromolecular dielectric enhancer is added during the preparation of the reactive macromolecular dielectric enhancer; instead, macromolecular dielectric enhancer c is added in an amount of 8.0 g, i.e.:

[0223] First, nitrogen was purged four times in a 15L high-pressure reactor. Then, 1550g of cyclohexane was added, and the temperature was raised to 124℃. 194g of methylaluminoxane co-catalyst was then added dropwise at a stirring speed of 850rpm. Stirring continued for 53min under inert gas protection. Subsequently, 8.0g of activated macromolecular dielectric enhancer c and 1100g of cyclohexane were mixed and stirred for 45min until completely dissolved. Then, 2g of trans-bromophenyl(di(triphenylphosphine))nickel was added to the high-pressure reactor. Ethylene was introduced at this time, and the pressure was maintained at 42MPa. The reaction was carried out for 9.2h. After the reaction was completed, the reactant macromolecular dielectric enhancer d was obtained by centrifugation and drying at 56℃.

[0224] (2) Preparation of polypropylene composite materials:

[0225] Other conditions are the same as in Example 4, except that reactive macromolecular dielectric reinforcing agents are not added during the preparation of the polypropylene composite material; instead, reactive macromolecular dielectric reinforcing agent d is added in an amount of 20g, i.e.:

[0226] A 15L high-pressure reactor was heated and evacuated to remove air and water. The reactor was then purged with nitrogen four times. 2.4g of a MgCl2-supported Ziegler-Natta solid catalyst (composed of TiCl4, diethylaluminum chloride, and ethyl benzoate) with an Al / Ti (molar ratio) of 70.5 and 20g of a reactive macromolecular dielectric enhancer d were added. Propylene and 500ppm of hydrogen were then introduced, maintaining a pressure of 26MPa and a reactor temperature of 81℃ to initiate polymerization. After 4.5 hours of reaction, unreacted gases were discharged to obtain polypropylene composite powder.

[0227] Sampling and analysis: Polypropylene composite powder was prepared into thin film samples according to standard methods and then subjected to dielectric tests. The test performance is shown in Table 1.

[0228] The melt mass flow rate (MFR) of the polypropylene composite powder is 9.1 g / 10 min.

[0229] Comparative Example 5

[0230] This comparative example prepares an activated macromolecular dielectric enhancer and uses it to prepare polypropylene composite materials.

[0231] (1) Preparation of activated macromolecular dielectric enhancer: Same as in Example 5.

[0232] (2) Preparation of polypropylene composite materials:

[0233] Other conditions are the same as in Example 5, except that no reactive macromolecular dielectric reinforcing agent is added during the preparation of the polypropylene composite material. Instead, an activated macromolecular dielectric reinforcing agent is added, and the amount added is 21g, i.e.:

[0234] A 15L high-pressure reactor was heated and evacuated to remove air and water. The reactor was then purged with nitrogen five times. 2.6g of a MgCl2-supported Ziegler-Natta solid catalyst (composed of TiCl4, diethylaluminum chloride, and ethyl benzoate) with an Al / Ti (molar ratio) of 76.2 was added. 21g of a macromolecular dielectric enhancer was activated. Propylene and 200ppm of hydrogen were then introduced, maintaining a pressure of 28MPa and a reactor temperature of 83℃ to initiate polymerization. After 4.8 hours of reaction, unreacted gases were discharged to obtain polypropylene composite powder.

[0235] Sampling and analysis: Polypropylene composite powder was prepared into thin film samples according to standard methods and then subjected to dielectric tests. The test performance is shown in Table 1.

[0236] The melt flow rate (MFR) of the polypropylene composite material was 8.3 g / 10 min.

[0237] Comparative Example 6

[0238] This comparative study prepared a reactive macromolecular dielectric enhancer and used it to prepare polypropylene composite materials.

[0239] (1) Preparation of reactive macromolecular dielectric enhancers:

[0240] a. Preparation of activated macromolecular dielectric enhancers: Same as in Example 6.

[0241] b. Preparation of reactive macromolecular dielectric enhancers: Same as in Example 6.

[0242] (2) Preparation of polypropylene composite materials:

[0243] Other conditions are the same as in Example 6, except that the amount of reactive macromolecular dielectric reinforcing agent added during the preparation of the polypropylene composite material is 10g, i.e.:

[0244] A 15L high-pressure reactor was heated and evacuated to remove air and water. The reactor was purged with nitrogen five times. Then, 2.2g of MgCl2-supported Ziegler-Natta solid catalyst (composed of TiCl4, trimethylaluminum, and 2,2-diphenyl-1,3-propanediol dimethyl ether) with an Al / Ti (molar ratio) of 80.0 and 10g of reactive macromolecular dielectric enhancer were added. Propylene and 2000ppm of hydrogen were then introduced, and the pressure was maintained at 30MPa and the reactor temperature at 85℃ to begin polymerization. After 5.0h of reaction, the unreacted gas was discharged to obtain polypropylene composite powder.

[0245] Sampling and analysis: Polypropylene composite powder was prepared into thin film samples according to standard methods and then subjected to dielectric tests. The test performance is shown in Table 1.

[0246] The melt mass flow rate (MFR) of the polypropylene composite powder is 7.9 g / 10 min.

[0247] Comparative Example 7

[0248] This comparative study prepared a reactive macromolecular dielectric enhancer and used it to prepare polypropylene composite materials.

[0249] (1) Preparation of reactive macromolecular dielectric enhancers:

[0250] a. Preparation of activated macromolecular dielectric enhancers: Same as in Example 1.

[0251] b. Preparation of reactive macromolecular dielectric enhancers: Same as in Example 1.

[0252] (2) Preparation of polypropylene composite materials:

[0253] Other conditions were the same as in Example 1, except that the polypropylene composite material was subjected to a weathering test in a xenon lamp aging chamber after preparation, at 0.55 W / m 2 Under light intensity, irradiation for 1000 hours, that is:

[0254] A 15L high-pressure reactor was heated and evacuated to remove air and water, and then purged with nitrogen three times. Next, 2g of a MgCl2-supported Ziegler-Natta solid catalyst (composed of TiCl4, triethylaluminum, and diisobutyl phthalate) with an Al / Ti (molar ratio) of 50.3 and 14g of a reactive macromolecular dielectric enhancer were added. Propylene and 1000ppm hydrogen were then introduced, maintaining a pressure of 20MPa and a reactor temperature of 75℃ to initiate polymerization. After 3.0 hours of reaction, unreacted gases were discharged to obtain polypropylene composite powder. This polypropylene composite powder was then placed in a xenon lamp aging chamber at 0.55W / m². 2 Irradiation for 1000 hours under the specified light intensity.

[0255] Sampling and analysis: The aged polypropylene composite powder was made into thin film samples according to the standard method and then subjected to dielectric testing. The test performance is shown in Table 1.

[0256] The melt mass flow rate (MFR) of the polypropylene composite powder is 7.8 g / 10 min.

[0257] Table 1 Properties of High Dielectric Constant Polypropylene Powder

[0258] Sample number Dielectric constant <![CDATA[Dielectric loss tgδ × 10 4 > MFR g / 10min Example 1 3.85 2.53 7.3 Example 2 3.87 2.65 7.1 Example 3 3.91 2.67 6.5 Example 4 3.96 2.72 6.1 Example 5 4.02 2.71 5.8 Example 6 4.13 2.75 5.4 Comparative Example 1 2.56 3.15 8.3 Comparative Example 2 1.54 3.28 8.1 Comparative Example 3 1.83 3.37 5.1 Comparative Example 4 2.81 3.65 9.1 Comparative Example 5 1.08 2.01 8.3 Comparative Example 6 3.25 3.95 7.9 Comparative Example 7 3.81 2.52 7.8

[0259] Table 1 shows that the polypropylene composite material of the present invention has a high dielectric constant and a low dielectric loss. The dielectric constant of Example 2 is much higher than that of Comparative Example 2, indicating that the modification effect of directly using the small molecule monomer methacrylamide is much lower than that of the modification effect of the large molecule methacrylamide homopolymer. The dielectric constant and dielectric loss of Example 1 are not significantly different from those of Comparative Example 7, indicating that the high dielectric constant polypropylene prepared by the present invention has good stability and durability. The melt flow rate (MFR) of Example 1 is not much different from that of Comparative Example 7, indicating that the high dielectric constant polypropylene prepared by the present invention still maintains high physical and mechanical strength after aging.

[0260] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. For those skilled in the art, other variations or modifications can be made based on the above description. It is impossible to exhaustively list all the implementation methods here. All obvious variations or modifications derived from the technical solutions of the present invention are still within the protection scope of the present invention.

Claims

1. A method for preparing a reactive macromolecular dielectric enhancer, wherein, The preparation method includes the following steps: An activated macromolecular dielectric enhancer was prepared by free radical polymerization of acrylamide-based polar monomers as shown in Formula (I), wherein 1,3-butadiene was used for end capping. The reactive macromolecular dielectric enhancer was obtained by reacting the obtained activated macromolecular dielectric enhancer with ethylene. （I） Wherein, R is selected from hydrogen and C1-C6 alkyl groups; The number-average molecular weight Mn of the activated macromolecular dielectric enhancer is 7000~15000; Based on 100 parts by mass of the acrylamide polar monomer, the amount of 1,3-butadiene is 2.0 to 4.0 parts; the amount of ethylene is used to maintain a reaction pressure of 35 to 45 MPa.

2. The preparation method according to claim 1, wherein, The acrylamide polar monomer is acrylamide or methacrylamide.

3. The preparation method according to claim 1, wherein, Based on 100 parts by mass of the acrylamide polar monomer, 0.3 to 0.5 parts by molecular weight regulator and 0.05 to 0.3 parts by initiator were also added during the free radical polymerization reaction of the acrylamide polar monomer.

4. The preparation method according to claim 3, wherein, The molecular weight regulator is selected from one of tert-decanethiol, tert-dodecanethiol, tert-tetradecylthiol, and tert-hexadecanethiol.

5. The preparation method according to claim 3, wherein, The initiator is selected from one or more combinations of diacetyl peroxide, diisobutyryl peroxide, cumene hydroperoxide, diisobutyryl peroxide, and dibenzoyl peroxide.

6. The preparation method according to claim 1, wherein, The free radical polymerization reaction is carried out in a solvent under a protective atmosphere; the reaction temperature of the free radical polymerization reaction is 70~85℃ and the time is 4.0~6.0 h.

7. The preparation method according to claim 1, wherein, The reaction between the activated macromolecular dielectric enhancer and ethylene specifically includes the following process: In a protective atmosphere, a nickel-based complex catalyst, an alkylaluminoxane co-catalyst, and an activated macromolecular dielectric enhancer are mixed with a solvent and then reacted with ethylene to obtain the reactive macromolecular dielectric enhancer. Based on 1 part by mass of the nickel-based complex catalyst, the amount of the activated macromolecular dielectric enhancer is 2.5 to 4.5 parts, and the amount of the alkylaluminoxane co-catalyst is 90 to 100 parts.

8. The preparation method according to claim 7, wherein, The nickel-based complex catalyst is selected from one of (1-naphthyl)[8-(diphenylphosphino)quinoline]nickel chloride, trans-phenyl bromide (di(triphenylphosphine))nickel, and 2,5-dicarboxypyrrole nickel dibromide.

9. The preparation method according to claim 7, wherein, The alkylaluminoxane cocatalyst is methylaluminoxane or ethylaluminoxane.

10. A reactive macromolecular dielectric enhancer, wherein, The reactive macromolecular dielectric enhancer is prepared according to the preparation method described in any one of claims 1-9.

11. A method for preparing a polypropylene composite material, wherein, The preparation method includes preparing the polypropylene composite material by polymerization reaction using the reactive macromolecular dielectric enhancer of claim 10 and propylene as raw materials.

12. The preparation method according to claim 11, wherein, The preparation method includes preparing the polypropylene composite material by polymerization reaction using the reactive macromolecular dielectric enhancer and propylene as raw materials in the presence of a supported Ziegler-Natta catalyst. With 1 part by weight of the supported Ziegler-Natta catalyst, the mass of the reactive macromolecular dielectric enhancer is 7 to 11 parts, and the amount of propylene is used to maintain a reaction pressure of 20 to 30 MPa.

13. The preparation method according to claim 11, wherein, The polymerization reaction of the reactive macromolecular dielectric enhancer and propylene is carried out at a temperature of 75-85°C and a reaction time of 3.0-5.0 h.

14. The preparation method according to claim 11, wherein, The preparation method includes: Under a protective atmosphere, a supported Ziegler-Natta catalyst and a reactive macromolecular dielectric enhancer are mixed, and propylene and hydrogen are introduced, wherein the volume concentration of hydrogen is 200~2000 ppm. The polymerization reaction is carried out at 75~85℃ and 20~30 MPa for 3.0~5.0 h to obtain the polypropylene composite material.

15. The preparation method according to claim 12 or 14, wherein, The supported Ziegler-Natta catalyst comprises a main catalyst and an organometallic co-catalyst; the main catalyst is a combination of one or more catalysts selected from ethyl benzoate, phthalic acid monoester or diester, monoether, diether or succinate as internal electron donors, with MgCl2 as support and TiCl4 as active center; the organometallic co-catalyst is composed of alkyl aluminum compounds.

16. The preparation method according to claim 15, wherein, The alkylaluminum compound is selected from one or more combinations of trimethylaluminum, triethylaluminum, triisobutylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum, diethylaluminum chloride, and ethylaluminum dichloride.

17. A polypropylene composite material obtained by the preparation method according to any one of claims 11-16.

18. The polypropylene composite material according to claim 17, wherein, The dielectric constant of the polypropylene composite material is 3.8~4.

2.

19. The polypropylene composite material according to claim 17, wherein, The dielectric loss of the polypropylene composite material is (2.53~2.75) tgδ×10 4 .

20. The polypropylene composite material according to claim 17, wherein, The melt mass flow rate (MFR) of the polypropylene composite material is (5.4~7.3) g / 10 min.

21. The use of the polypropylene composite material according to any one of claims 17-20 in the preparation of film capacitors or lithium battery separators.

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