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 unsaturated carboxylic acid and the acrylamide polar monomer are polymerized to obtain the activated macromolecular dielectric reinforcing agent with high polarity; then the reactive macromolecular dielectric reinforcing agent is obtained by polymerizing with ethylene. The reactive macromolecular dielectric reinforcing agent is added into the polypropylene polymerization reaction to prepare the polypropylene composite material with high dielectric constant by coordination polymerization. The macromolecular dielectric reinforcing agent is realized, the uniformity and regularity of the polar group carboxyl and amide group distributed on the polypropylene molecular segment are improved, and the polypropylene composite material is endowed with the characteristics of high efficiency and durability of dielectric properties.

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 using acrylamide polar monomers of formula (I) and unsaturated carboxylic acid polar monomers of formula (II), 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] In the formula, R1 and R2 are independently selected from hydrogen and C1 to C6 alkyl groups;

[0019] The number-average molecular weight (Mn) of the activated macromolecular dielectric enhancer is 9000–17000;

[0020] Based on a total mass of 100 parts of acrylamide polar monomers and unsaturated carboxylic acid polar monomers, the acrylamide polar monomers comprise 70-80 parts, the unsaturated carboxylic acid polar monomers comprise 20-30 parts, and the 1,3-butadiene comprises 3.0-5.0 parts; the amount of ethylene used is to maintain a reaction pressure of 35-45 MPa.

[0021] The structural formula of the prepared activated macromolecular dielectric enhancer can be shown as formula (III):

[0022]

[0023] R1 and R2 are defined as above, where h is the number of repeating units, and h ≥ 1.

[0024] The structure of the prepared reactive macromolecular dielectric enhancer can be schematically represented by the following formula (IV):

[0025]

[0026] R1 and R2 are defined as above, and m and L are the number of repeating units in the corresponding chain segment, where m = 10 to 20 and L = 15 to 30.

[0027] According to some specific embodiments of the present invention, R1 is hydrogen or methyl.

[0028] According to some specific embodiments of the present invention, R2 is selected from hydrogen and C1 to C4 alkyl groups; preferably, R2 is methyl.

[0029] 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.

[0030] According to some specific embodiments of the present invention, the acrylamide polar monomer is acrylamide or methacrylamide.

[0031] According to some specific embodiments of the present invention, the acrylamide polar monomer is methacrylamide.

[0032] According to some specific embodiments of the present invention, the unsaturated carboxylic acid polar monomer is selected from one of acrylic acid (AA), methacrylic acid (MAA), 2-ethylacrylic acid, 2-propylacrylic acid and 2-n-butylacrylic acid.

[0033] According to some specific embodiments of the present invention, the unsaturated carboxylic acid polar monomer is methacrylic acid.

[0034] According to some specific embodiments of the present invention, wherein, based on a total mass of 100 parts of the acrylamide polar monomer and the unsaturated carboxylic acid polar monomer, 0.5 to 0.7 parts of a molecular weight regulator and 0.07 to 0.4 parts of an initiator are also added during the free radical polymerization reaction.

[0035] 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.

[0036] According to some specific embodiments of the present invention, the initiator is an organic peroxide.

[0037] 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 benzoyl peroxide (BPO).

[0038] According to some specific embodiments of the present invention, the initiator is benzoyl peroxide (BPO).

[0039] 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 80–90°C, and the time is 5.0–7.0 h. The protective gas is, for example, nitrogen or a rare gas, such as helium or argon.

[0040] According to some specific embodiments of the present invention, the preparation process of the activated macromolecular dielectric enhancer includes: mixing the acrylamide polar monomer, the unsaturated carboxylic acid polar monomer, the molecular weight regulator and the solvent in a protective atmosphere, then adding an initiator at 80-90°C, reacting for 5.0-7.0 h, and then adding 1,3-butadiene for end-capping to obtain the activated macromolecular dielectric enhancer.

[0041] 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.

[0042] Based on 1 part by mass of the nickel-based complex catalyst, the amount of the activated macromolecular dielectric enhancer is 3.0 to 5.0 parts, and the amount of the alkylaluminoxane co-catalyst is 90 to 100 parts.

[0043] 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, 800-900 parts of solvent are heated to 120-140°C in a reaction vessel, and 90-100 parts of alkylaluminoxane co-catalyst are added dropwise while stirring at 850-950 rpm, with stirring continuing for 50-70 min; subsequently, 3.0-5.0 parts of the activated macromolecular dielectric enhancer and 500-700 parts of solvent are mixed and stirred to dissolve for 40-60 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 50-70°C. Preferably, the reaction vessel is a high-pressure reactor.

[0044] 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.

[0045] According to some specific embodiments of the present invention, the nickel-based complex catalyst is nickel chloride (1-naphthyl)[8-(diphenylphosphino)quinoline].

[0046] According to some specific embodiments of the present invention, the alkylaluminoxane cocatalyst is methylaluminoxane (MAO) or ethylaluminoxane (EAO).

[0047] According to some specific embodiments of the present invention, the alkylaluminoxane cocatalyst is methylaluminoxane.

[0048] According to some specific embodiments of the present invention, the solvent is a hydrocarbon solvent.

[0049] 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.

[0050] According to some specific embodiments of the present invention, the protective gas atmosphere is achieved by purging the reaction vessel with a protective gas multiple times. Alternatively, other commonly used methods for creating a protective gas atmosphere can also be used.

[0051] 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.

[0052] According to some specific embodiments of the present invention, the structure of the reactive macromolecular dielectric enhancer can be schematically represented as formula (IV):

[0053]

[0054] In the formula, R1 is selected from hydrogen and C1 to C6 alkyl groups; R2 is selected from hydrogen and C1 to C4 alkyl groups; m and L are the number of repeating units in the corresponding chain segment, m = 10 to 20, L = 15 to 30.

[0055] According to some specific embodiments of the present invention, R1 is hydrogen or methyl.

[0056] According to some specific embodiments of the present invention, R2 is methyl.

[0057] 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.

[0058] 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 4.0 to 7.0 parts, and the amount of propylene is used to maintain a reaction pressure of 20 to 30 MPa.

[0059] 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 80-90°C and a reaction time of 4.0-6.0 h.

[0060] According to some specific embodiments of the present invention, the preparation method includes:

[0061] 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 80-90°C and 20-30 MPa for 4.0-6.0 h to obtain the polypropylene composite material.

[0062] According to some specific embodiments of the present invention, the protective gas atmosphere is achieved by purging the reaction vessel with a protective gas multiple times. Alternatively, other commonly used methods for creating a protective gas atmosphere can also be used.

[0063] According to some specific embodiments of the present invention, the preparation method includes:

[0064] 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 4.0 to 7.0 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 80 to 90 °C to start polymerization. After 4.0 to 6.0 h of reaction, the unreacted gas is discharged to obtain the polypropylene composite material powder.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] According to some specific embodiments of the present invention, the alkylaluminum compound is triethylaluminum.

[0069] According to some specific embodiments of the present invention, the internal electron donor is diisobutyl phthalate.

[0070] 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.

[0071] 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.

[0072] 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.

[0073] 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.

[0074] In another aspect, the present invention provides a polypropylene composite material obtained by any of the above preparation methods.

[0075] According to some specific embodiments of the present invention, the dielectric constant of the polypropylene composite material is ≥4.3.

[0076] According to some specific embodiments of the present invention, the dielectric constant of the polypropylene composite material is 4.3 to 4.9.

[0077] According to some specific embodiments of the present invention, the dielectric loss of the polypropylene composite material is less than 3.0 tgδ × 10 4 .

[0078] According to some specific embodiments of the present invention, the dielectric loss of the polypropylene composite material is (2.6~3.0)tgδ×10 4 .

[0079] According to some specific embodiments of the present invention, the melt mass flow rate (MFR) of the polypropylene composite material is (4.3 to 7.0) g / 10 min.

[0080] The present invention also provides the application of the polypropylene composite material in the preparation of thin-film capacitors or lithium battery separators.

[0081] This invention first synthesizes a highly polar reactive macromolecular dielectric enhancer using small-molecule unsaturated carboxylic acids and acrylamide-based polar monomers via free radical polymerization. Second, in the presence of a nickel-based complexing catalyst, a reactive macromolecular dielectric enhancer with coordination polymerization activity is prepared from the reactive monomer ethylene and the reactive macromolecular dielectric enhancer. Finally, the reactive macromolecular dielectric enhancer and propylene are polymerized to produce polypropylene with a high dielectric constant. This method achieves macromolecularization of the dielectric enhancer, improves the uniformity and regularity of the distribution of polar carboxyl and amide groups on the polypropylene molecular chain, and endows the polypropylene resin with high efficiency and durability in dielectric properties.

[0082] The beneficial effects of this invention include:

[0083] 1) The reactive macromolecular dielectric enhancer prepared by this invention can be widely distributed on the main chain segment of polypropylene through coordination polymerization, which improves the uniformity and dispersion of highly polar groups such as carboxyl and amide groups in the polypropylene matrix.

[0084] 2) The polypropylene composite material prepared by this invention has the characteristics of high efficiency and durability in dielectric properties, which allows high dielectric constant polypropylene with a dielectric constant greater than 4.3 to be obtained when the dielectric reinforcing agent is added at a low amount. It is suitable for use in related products that require high dielectric constant, such as film capacitors and lithium battery separators.

[0085] 3) The preparation method of the polypropylene composite material of the present invention is simple and low in cost. The polypropylene composite material has stable performance and is suitable for industrial production. Detailed Implementation

[0086] 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.

[0087] 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".

[0088] (1) Source of raw materials:

[0089] Ethylene, 99% purity, from Lanzhou Petrochemical Company of China National Petroleum Corporation;

[0090] Propylene, 99% purity, from Lanzhou Petrochemical Company of China National Petroleum Corporation;

[0091] Methacrylamide, Ningbo Yingrunde Chemical Co., Ltd.;

[0092] Methacrylic acid, Lanzhou Petrochemical Company of China National Petroleum Corporation;

[0093] Dicumyl peroxide (DCP), Lanzhou Additives Factory;

[0094] Diisobutyl phthalate, Nanjing Chemical Reagent Co., Ltd.;

[0095] All other reagents are commercially available industrial products.

[0096] (2) Analysis and testing methods:

[0097] Preparation method of polypropylene film samples:

[0098] 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.

[0099] Dielectric testing:

[0100] 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.

[0101] Determination of molecular weight and its distribution:

[0102] 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 .

[0103] Determination of melt mass flow rate (MFR):

[0104] The method in standard GB / T 3682-2000 shall be followed.

[0105] Weather resistance test:

[0106] Performed according to SAE J2527-2004, with an illumination amplitude of 0.55 W / m. 2 The test lasted for 1000 hours.

[0107] Example 1

[0108] This embodiment prepares a reactive macromolecular dielectric enhancer and uses it to prepare a polypropylene composite material.

[0109] (1) Preparation of reactive macromolecular dielectric enhancers:

[0110] a. Preparation of activated macromolecular dielectric enhancers:

[0111] First, nitrogen gas was purged three times in a 5L jacketed stainless steel reactor. Then, 1500g of toluene, 100g of methacrylic acid, 400g of methacrylamide, 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 80℃. Then, 0.35g of BPO 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 40min until no free monomers were present. After the reaction was completed, the mixture was washed with hexane and dried at 60℃ to obtain the activated macromolecular dielectric enhancer.

[0112] The activated macromolecular dielectric enhancer was prepared with a number-average molecular weight Mn of 9000.

[0113] b. Preparation of reactive macromolecular dielectric enhancers:

[0114] First, nitrogen was purged three times in a 15L high-pressure reactor. Then, 1600g of toluene was added, and the temperature was raised to 120℃. 180g of methylaluminoxane co-catalyst was then added dropwise at a stirring speed of 850rpm. Stirring continued for 50min under nitrogen protection. Subsequently, 6g of activated macromolecular dielectric enhancer and 1000g of toluene were mixed and stirred for 40min 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 55℃.

[0115] (2) Preparation of polypropylene composite materials:

[0116] 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 50.1 and 8.0g of a reactive macromolecular dielectric enhancer were then introduced. Propylene and a small amount of hydrogen (1000ppm) were then introduced, maintaining a pressure of 20MPa and a reactor temperature of 80℃ to initiate polymerization. After 4.0h of reaction, unreacted gases were discharged to obtain polypropylene composite powder.

[0117] 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.

[0118] The melt mass flow rate (MFR) of the polypropylene composite powder is 6.9 g / 10 min.

[0119] Example 2

[0120] This embodiment prepares a reactive macromolecular dielectric enhancer and uses it to prepare a polypropylene composite material.

[0121] (1) Preparation of reactive macromolecular dielectric enhancers:

[0122] a. Preparation of activated macromolecular dielectric enhancers:

[0123] First, nitrogen gas was purged three times in a 5L jacketed stainless steel reactor. Then, 1600g of toluene, 110g of methacrylic acid, 390g of methacrylamide, and 2.7g of tert-dodecyl mercaptan were added to the reactor in sequence. The mixture was stirred and heated until the reactor temperature reached 82℃. Then, 0.41g of BPO was added and the reaction was carried out for 5.5h. 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 62℃ to obtain the activated macromolecular dielectric enhancer.

[0124] The number-average molecular weight (Mn) of the activated macromolecular dielectric enhancer is 11000.

[0125] b. Preparation of reactive macromolecular dielectric enhancers:

[0126] First, nitrogen was purged three times in a 15L high-pressure reactor. Then, 1650g of toluene was added, and the temperature was raised to 125℃. 185g of methylaluminoxane co-catalyst was then added dropwise at a stirring speed of 880rpm, and stirring was continued for 55min under nitrogen protection. Subsequently, 7g of activated macromolecular dielectric enhancer and 1100g of toluene were mixed and stirred for 45min 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 8.5h. After the reaction was completed, the reactive macromolecular dielectric enhancer was obtained by centrifugation and drying at 57℃.

[0127] (2) Preparation of polypropylene composite materials:

[0128] A 15L high-pressure reactor was heated and evacuated to remove air and water. The reactor was then purged with nitrogen three times. 1.91g of a MgCl2-supported Ziegler-Natta solid catalyst (composed of TiCl4, triethylaluminum, and diisobutyl phthalate) with an Al / Ti (molar ratio) of 57.3 and 9.0g of a reactive macromolecular dielectric enhancer were then introduced. Propylene and a small amount of hydrogen (800ppm) were then introduced, maintaining the pressure at 22MPa and the reactor temperature at 82℃ to initiate polymerization. After 4.5 hours of reaction, the unreacted gas was discharged to obtain polypropylene composite powder.

[0129] 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.

[0130] The melt mass flow rate (MFR) of the polypropylene composite powder is 6.3 g / 10 min.

[0131] Example 3

[0132] This embodiment prepares a reactive macromolecular dielectric enhancer and uses it to prepare a polypropylene composite material.

[0133] (1) Preparation of reactive macromolecular dielectric enhancers:

[0134] a. Preparation of activated macromolecular dielectric enhancers:

[0135] First, nitrogen gas was purged four times in a 5L jacketed stainless steel reactor. Then, 1700g of toluene, 120g of methacrylic acid, 380g of methacrylamide, and 2.9g of tert-dodecyl mercaptan were added to the reactor in sequence. The mixture was stirred and heated until the reactor temperature reached 85℃. Then, 0.52g of BPO was added and the reaction was carried out for 6.0h. Then, 19g 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 hexane and dried at 64℃ to obtain the activated macromolecular dielectric enhancer.

[0136] The number-average molecular weight (Mn) of the activated macromolecular dielectric enhancer is 13,000.

[0137] b. Preparation of reactive macromolecular dielectric enhancers:

[0138] First, nitrogen was purged four times in a 15L high-pressure reactor. Then, 1700g of toluene was added, and the temperature was raised to 130℃. 190g of methylaluminoxane co-catalyst was then added dropwise at a stirring speed of 900rpm. Stirring continued for 60min under nitrogen protection. Subsequently, 8g of activated macromolecular dielectric enhancer and 1200g of toluene were mixed and stirred for 50min 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 60℃.

[0139] (2) Preparation of polypropylene composite materials:

[0140] A 15L high-pressure reactor was heated and evacuated to remove air and water. The reactor was then purged with nitrogen four times. 2.17g of a MgCl2-supported Ziegler-Natta solid catalyst (composed of TiCl4, triethylaluminum, and diisobutyl phthalate) with an Al / Ti (molar ratio) of 65.1 and 10g of a reactive macromolecular dielectric enhancer were then introduced. Propylene and a small amount of hydrogen (1200ppm) were then introduced, maintaining a pressure of 24MPa and a reactor temperature of 84℃ to initiate polymerization. After 5.0h of reaction, unreacted gases were discharged to obtain polypropylene composite powder.

[0141] 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.

[0142] The melt mass flow rate (MFR) of the polypropylene composite powder is 6.0 g / 10 min.

[0143] Example 4

[0144] This embodiment prepares a reactive macromolecular dielectric enhancer and uses it to prepare a polypropylene composite material.

[0145] (1) Preparation of reactive macromolecular dielectric enhancers:

[0146] a. Preparation of activated macromolecular dielectric enhancers:

[0147] First, nitrogen gas was purged four times in a 5L jacketed stainless steel reactor. Then, 1800g of toluene, 130g of methacrylic acid, 370g of methacrylamide, and 3.0g of tert-dodecyl mercaptan were added to the reactor in sequence. The mixture was stirred and heated until the reactor temperature reached 87℃. Then, 0.65g of BPO was added and the reaction was carried out for 6.3h. Then, 20g of 1,3-butadiene was added to the polymerization reactor for end-capping and the reaction was carried out for 54min 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.

[0148] The number-average molecular weight (Mn) of the activated macromolecular dielectric enhancer is 14,000.

[0149] b. Preparation of reactive macromolecular dielectric enhancers:

[0150] First, nitrogen was purged four times in a 15L high-pressure reactor. Then, 1740g of toluene was added, and the temperature was raised to 135℃. 193g of ethylaluminoxane co-catalyst was then added dropwise at a stirring speed of 920rpm, and stirring was continued for 63min under nitrogen protection. Subsequently, 8.5g of activated macromolecular dielectric enhancer and 1300g of toluene were mixed and stirred for 52min 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 9.3h. After the reaction was completed, the reactive macromolecular dielectric enhancer was obtained by centrifugation and drying at 61℃.

[0151] (2) Preparation of polypropylene composite materials:

[0152] A 15L high-pressure reactor was heated and evacuated to remove air and water. The reactor was then purged with nitrogen four times. 2.64g of a MgCl2-supported Ziegler-Natta solid catalyst (composed of TiCl4, diethylaluminum chloride, and ethyl benzoate) with an Al / Ti (molar ratio) of 71.2 and 11g of a reactive macromolecular dielectric enhancer were then introduced. Propylene and a small amount of hydrogen (500ppm) were then introduced, maintaining the pressure at 26MPa and the reactor temperature at 86℃ to initiate polymerization. After 5.3 hours of reaction, unreacted gases were discharged to obtain polypropylene composite powder.

[0153] 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.

[0154] The melt mass flow rate (MFR) of the polypropylene composite powder is 5.3 g / 10 min.

[0155] Example 5

[0156] This embodiment prepares a reactive macromolecular dielectric enhancer and uses it to prepare a polypropylene composite material.

[0157] (1) Preparation of reactive macromolecular dielectric enhancers:

[0158] a. Preparation of activated macromolecular dielectric enhancers:

[0159] First, in a 5L stainless steel reactor with a jacket, nitrogen was purged five times. Then, 1800g of xylene, 140g of acrylic acid, 360g of methacrylamide, and 3.2g of tert-dodecyl mercaptan were added sequentially to the reactor. The mixture was stirred and heated until the reactor temperature reached 89℃. Then, 0.71g of BPO was added and the reaction was carried out for 6.6h. Then, 23g of 1,3-butadiene was added to the polymerization reactor for end-capping and the reaction was carried out for 57min 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.

[0160] The number-average molecular weight (Mn) of the activated macromolecular dielectric enhancer is 16,000.

[0161] b. Preparation of reactive macromolecular dielectric enhancers:

[0162] First, nitrogen was purged five times in a 15L high-pressure reactor. Then, 1760g of xylene was added, and the temperature was raised to 137℃. 196g of ethylaluminoxane co-catalyst was then added dropwise at a stirring speed of 940rpm, and stirring was continued for 68min under nitrogen protection. Subsequently, 9.5g of activated macromolecular dielectric enhancer and 1370g of xylene were mixed and stirred for 55min 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 43MPa. 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 63℃.

[0163] (2) Preparation of polypropylene composite materials:

[0164] A 15L high-pressure reactor was heated and evacuated to remove air and water. The reactor was then purged with nitrogen five times. 2.82g of a MgCl2-supported Ziegler-Natta solid catalyst (composed of TiCl4, diethylaluminum chloride, and ethyl benzoate) with an Al / Ti (molar ratio) of 76.5 was added, along with 12g of a reactive macromolecular dielectric enhancer. Propylene and a small amount of hydrogen (200ppm) were then introduced, maintaining a pressure of 28MPa and a reactor temperature of 88℃ to initiate polymerization. After 5.6 hours of reaction, unreacted gases were discharged to obtain polypropylene composite powder.

[0165] 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.

[0166] The melt mass flow rate (MFR) of the polypropylene composite powder is 4.7 g / 10 min.

[0167] Example 6

[0168] This embodiment prepares a reactive macromolecular dielectric enhancer and uses it to prepare a polypropylene composite material.

[0169] (1) Preparation of reactive macromolecular dielectric enhancers:

[0170] a. Preparation of activated macromolecular dielectric enhancers:

[0171] First, in a 5L stainless steel reactor with a jacket, nitrogen was purged five times. Then, 2000g of xylene, 150g of acrylic acid, 350g of acrylamide, and 3.5g of tert-dodecyl mercaptan were added to the reactor in sequence. The mixture was stirred and heated until the reactor temperature reached 90℃. Then, 0.86g of BPO was added and the reaction was carried out for 7.0h. Then, 25g of 1,3-butadiene was added to the polymerization reactor for end-capping and the reaction was carried out for 60min until no free monomers were present. After the reaction was completed, the mixture was washed with hexane and dried at 70℃ to obtain the activated macromolecular dielectric enhancer.

[0172] The number-average molecular weight (Mn) of the activated macromolecular dielectric enhancer is 17,000.

[0173] b. Preparation of reactive macromolecular dielectric enhancers:

[0174] First, nitrogen was purged five times in a 15L high-pressure reactor. Then, 1800g of xylene was added, and the temperature was raised to 140℃. 200g of ethylaluminoxane co-catalyst was then added dropwise at a stirring speed of 950rpm. Stirring continued for 70min under nitrogen protection. Subsequently, 10g of activated macromolecular dielectric enhancer and 1400g of xylene were mixed and stirred for 60min 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 63℃.

[0175] (2) Preparation of polypropylene composite materials:

[0176] A 15L high-pressure reactor was heated and evacuated to remove air and water. The reactor was purged with nitrogen five times. Then, 2.91g of a 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 14g of a reactive macromolecular dielectric enhancer were added. Propylene and a small amount of hydrogen (2000ppm) were then introduced, and the pressure was maintained at 30MPa and the reactor temperature at 90℃. Polymerization was initiated, and after 6.0h of reaction, the unreacted gas was discharged to obtain polypropylene composite powder.

[0177] 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.

[0178] The melt mass flow rate (MFR) of the polypropylene composite powder is 4.3 g / 10 min.

[0179] Comparative Example 1

[0180] This comparative study prepared a reactive macromolecular dielectric enhancer a and used it to prepare polypropylene composite materials.

[0181] (1) Preparation of reactive macromolecular dielectric enhancers:

[0182] a. Preparation of activated macromolecular dielectric enhancers:

[0183] Other conditions are the same as in Example 1, except that methyl methacrylate is added instead of methacrylic acid in the preparation of the activated macromolecular dielectric enhancer, and the amount added is 100g.

[0184] First, in a 5L stainless steel reactor with a jacket, nitrogen was purged three times. Then, 1500g of toluene, 100g of methyl methacrylate, 400g of methacrylamide, 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 80℃. Then, 0.35g of BPO 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 40min until no free monomers were present. After the reaction was completed, the mixture was washed with hexane and dried at 60℃ to obtain activated macromolecular dielectric enhancer a.

[0185] The number-average molecular weight Mn of the activated macromolecular dielectric enhancer a is 7000.

[0186] b. Preparation of reactive macromolecular dielectric enhancers:

[0187] Other conditions are the same as in Example 1, except that no activated macromolecular dielectric enhancer is added during the preparation of the reactive macromolecular dielectric enhancer; instead, activated macromolecular dielectric enhancer a is added in an amount of 6.0 g, i.e.:

[0188] First, nitrogen was purged three times in a 15L high-pressure reactor. Then, 1600g of toluene was added, and the temperature was raised to 120℃. 180g of methylaluminoxane co-catalyst was then added dropwise at a stirring speed of 850rpm. Stirring continued for 50min under nitrogen protection. Subsequently, 6.0g of activated macromolecular dielectric enhancer a and 1000g of toluene were mixed and stirred for 40min 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 55℃.

[0189] (2) Preparation of polypropylene composite materials:

[0190] 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 8.0 g, i.e.:

[0191] 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 50.1 and 8.0g of reactive macromolecular dielectric enhancer a were then added. Propylene and a small amount of hydrogen (1000ppm) were then introduced, maintaining a pressure of 20MPa and a reactor temperature of 80℃ to initiate polymerization. After 4.0h of reaction, unreacted gases were discharged to obtain polypropylene composite powder.

[0192] 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.

[0193] The melt mass flow rate (MFR) of the polypropylene composite powder is 7.9 g / 10 min.

[0194] Comparative Example 2

[0195] This comparative study prepared a reactive macromolecular dielectric enhancer b and used it to prepare polypropylene composite materials.

[0196] (1) Preparation of reactive macromolecular dielectric enhancers:

[0197] a. Preparation of activated macromolecular dielectric enhancers:

[0198] Other conditions are the same as in Example 2, except that methacrylamide is not added during the preparation of the activated macromolecular dielectric enhancer, i.e.:

[0199] First, nitrogen gas was purged three times in a 5L stainless steel reactor with a jacket. Then, 1600g of toluene, 110g of methacrylic acid, and 2.7g of tert-dodecyl mercaptan were added to the reactor in sequence. The mixture was stirred and heated until the reactor temperature reached 82℃. Then, 0.41g of BPO was added and the reaction was carried out for 5.5h. 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 62℃ to obtain activated macromolecular dielectric enhancer b.

[0200] The number-average molecular weight (Mn) of the activated macromolecular dielectric enhancer b is 8000.

[0201] b. Preparation of reactive macromolecular dielectric enhancers:

[0202] Other conditions are the same as in Example 2, except that no activated macromolecular dielectric enhancer is added during the preparation of the reactive macromolecular dielectric enhancer; instead, activated macromolecular dielectric enhancer b is added in an amount of 7.0 g, i.e.:

[0203] First, nitrogen was purged three times in a 15L high-pressure reactor. Then, 1650g of toluene was added, and the temperature was raised to 125℃. 185g of methylaluminoxane co-catalyst was then added dropwise at a stirring speed of 880rpm. Stirring continued for 55min under nitrogen protection. Subsequently, 7.0g of activated macromolecular dielectric enhancer and 1100g of toluene were mixed and stirred for 45min 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 8.5h. After the reaction was completed, the reactive macromolecular dielectric enhancer b was obtained by centrifugation and drying at 57℃.

[0204] (2) Preparation of polypropylene composite materials:

[0205] 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 9.0 g, i.e.:

[0206] A 15L high-pressure reactor was heated and evacuated to remove air and water. The reactor was then purged with nitrogen three times. 1.91g of a MgCl2-supported Ziegler-Natta solid catalyst (composed of TiCl4, triethylaluminum, and diisobutyl phthalate) with an Al / Ti (molar) ratio of 57.3 and 9.0g of a reactive macromolecular dielectric enhancer b were then introduced. Propylene and a small amount of hydrogen (800ppm) were then introduced, maintaining the pressure at 22MPa and the reactor temperature at 82℃ to initiate polymerization. After 4.5 hours of reaction, the unreacted gas was discharged to obtain polypropylene composite powder.

[0207] 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.

[0208] The melt mass flow rate (MFR) of the polypropylene composite powder is 7.2 g / 10 min.

[0209] Comparative Example 3

[0210] This comparative study prepared a reactive macromolecular dielectric enhancer c and used it to prepare polypropylene composite materials.

[0211] (1) Preparation of reactive macromolecular dielectric enhancers:

[0212] a. Preparation of activated macromolecular dielectric enhancers:

[0213] Other conditions are the same as in Example 3, except that 1,3-butadiene is not added during the preparation of the activated macromolecular dielectric enhancer, i.e.:

[0214] First, nitrogen gas was purged four times in a 5L stainless steel reactor with a jacket. Then, 1700g of toluene, 120g of methacrylic acid, 380g of methacrylamide, and 2.9g of tert-dodecyl mercaptan were added to the reactor in sequence. The mixture was stirred and heated. When the reactor temperature reached 85℃, 0.52g of BPO was added. The reaction was carried out for 6.0h. After the reaction was completed, the mixture was washed and dried at 64℃ to obtain activated macromolecular dielectric enhancer c.

[0215] The number-average molecular weight (Mn) of the activated macromolecular dielectric enhancer c is 13000.

[0216] b. Preparation of reactive macromolecular dielectric enhancers:

[0217] Other conditions are the same as in Example 3, except that no activated macromolecular dielectric enhancer is added during the preparation of the reactive macromolecular dielectric enhancer; instead, activated macromolecular dielectric enhancer c is added in an amount of 8.0 g, i.e.:

[0218] First, nitrogen was purged four times in a 15L high-pressure reactor. Then, 1700g of toluene was added, and the temperature was raised to 130℃. 190g of methylaluminoxane co-catalyst was then added dropwise at a stirring speed of 900rpm, and stirring was continued for 60min under nitrogen protection. Subsequently, 8.0g of activated macromolecular dielectric enhancer c and 1200g of toluene were mixed and stirred for 50min 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 60℃.

[0219] (2) Preparation of polypropylene composite materials:

[0220] 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 10.0 g, i.e.:

[0221] A 15L high-pressure reactor was heated and evacuated to remove air and water. The reactor was then purged with nitrogen four times. 2.17g of a MgCl2-supported Ziegler-Natta solid catalyst (composed of TiCl4, triethylaluminum, and diisobutyl phthalate) with an Al / Ti (molar ratio) of 65.1 and 10.0g of a reactive macromolecular dielectric enhancer (c) were then introduced. Propylene and a small amount of hydrogen (1200ppm) were then introduced, maintaining the pressure at 24MPa and the reactor temperature at 84℃ to initiate polymerization. After 5.0h of reaction, the unreacted gas was discharged to obtain polypropylene composite powder.

[0222] 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.

[0223] The melt mass flow rate (MFR) of the polypropylene composite powder is 8.4 g / 10 min.

[0224] Comparative Example 4

[0225] This comparative study prepared a reactive macromolecular dielectric enhancer d and used it to prepare polypropylene composite materials.

[0226] (1) Preparation of reactive macromolecular dielectric enhancers:

[0227] 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; only small molecule methacrylic acid is added, and the amount added is 8.5g, i.e.:

[0228] First, nitrogen was purged four times in a 15L high-pressure reactor. Then, 1740g of toluene was added, and the temperature was raised to 135℃. 193g of ethylaluminoxane co-catalyst was then added dropwise at a stirring speed of 920rpm, and stirring was continued for 63min under nitrogen protection. Subsequently, 8.5g of methacrylic acid and 1300g of toluene were mixed and stirred to dissolve for 52min. 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 9.3h. After the reaction was completed, the reactive macromolecular dielectric enhancer d was obtained by centrifugation and drying at 61℃.

[0229] (2) Preparation of polypropylene composite materials:

[0230] 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 11.0 g, i.e.:

[0231] A 15L high-pressure reactor was heated and evacuated to remove air and water. The reactor was then purged with nitrogen four times. 2.64g of a MgCl2-supported Ziegler-Natta solid catalyst (composed of TiCl4, diethylaluminum chloride, and ethyl benzoate) with an Al / Ti (molar ratio) of 71.2 and 11.0g of a reactive macromolecular dielectric enhancer d were then introduced. Propylene and a small amount of hydrogen (500ppm) were then introduced, maintaining the pressure at 26MPa and the reactor temperature at 86℃ to initiate polymerization. After 5.3 hours of reaction, unreacted gases were discharged to obtain polypropylene composite powder.

[0232] 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.

[0233] The melt mass flow rate (MFR) of the polypropylene composite powder is 7.6 g / 10 min.

[0234] Comparative Example 5

[0235] This comparative example prepares an activated macromolecular dielectric enhancer and uses it to prepare polypropylene composite materials.

[0236] (1) Preparation of activated macromolecular dielectric enhancers:

[0237] Same as Example 5.

[0238] (2) Preparation of polypropylene composite materials:

[0239] 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 in an amount of 12g, i.e.:

[0240] A 15L high-pressure reactor was heated and evacuated to remove air and water. The reactor was then purged with nitrogen five times. 2.82g of a MgCl2-supported Ziegler-Natta solid catalyst (composed of TiCl4, diethylaluminum chloride, and ethyl benzoate) with an Al / Ti (molar ratio) of 76.5 was added. 12g of a macromolecular dielectric enhancer was activated. Propylene and a small amount of hydrogen (200ppm) were then introduced, maintaining a pressure of 28MPa and a reactor temperature of 88℃ to initiate polymerization. After 5.6 hours of reaction, unreacted gases were discharged to obtain polypropylene composite powder.

[0241] 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.

[0242] The melt mass flow rate (MFR) of the polypropylene composite powder is 6.1 g / 10 min.

[0243] Comparative Example 6

[0244] This comparative study prepared a reactive macromolecular dielectric enhancer and used it to prepare polypropylene composite materials.

[0245] (1) Preparation of reactive macromolecular dielectric enhancers:

[0246] Same as Example 6.

[0247] (2) Preparation of polypropylene composite materials:

[0248] Other conditions were 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 was 5.0 g, i.e.:

[0249] A 15L high-pressure reactor was heated and evacuated to remove air and water. The reactor was purged with nitrogen five times. Then, 2.91g of a 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 5.0g of a reactive macromolecular dielectric enhancer were added. Propylene and a small amount of hydrogen (2000ppm) were then introduced, and the pressure was maintained at 30MPa and the reactor temperature at 90℃ to begin polymerization. After 6.0h of reaction, the unreacted gas was discharged to obtain polypropylene composite powder.

[0250] 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.

[0251] The melt mass flow rate (MFR) of the polypropylene composite powder is 4.1 g / 10 min.

[0252] Comparative Example 7

[0253] This comparative study prepared a reactive macromolecular dielectric enhancer and used it to prepare polypropylene composite materials.

[0254] (1) Preparation of reactive macromolecular dielectric enhancers:

[0255] Same as Example 6.

[0256] (2) Preparation of polypropylene composite materials:

[0257] Other conditions were 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 was 5.0 g, i.e.:

[0258] A 15L high-pressure reactor was heated and evacuated to remove air and water, and purged with nitrogen five times. Then, 2.91g of a 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 5.0g of a reactive macromolecular dielectric enhancer were added. Propylene and a small amount of hydrogen (2000ppm) were then introduced, maintaining a pressure of 30MPa and a reactor temperature of 90℃ to initiate polymerization. After 6.0 hours of reaction, unreacted gases were discharged to obtain polypropylene composite powder. The 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.

[0259] 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.

[0260] The melt mass flow rate (MFR) of the polypropylene composite powder is 4.6 g / 10 min.

[0261] Table 1 Properties of High Dielectric Constant Polypropylene Powder

[0262]

[0263]

[0264] As shown in Table 1, based on the comparison of the examples and comparative examples, the polypropylene composite material of the present invention exhibits both high dielectric constant and low dielectric loss. The dielectric constant of Example 4 is significantly higher than that of Comparative Example 4, indicating that the modification effect of directly using the small-molecule monomer methacrylic acid is far less than that of modifying with the copolymer of large-molecule methacrylic acid and methacrylamide. The dielectric constant and dielectric loss of Example 6 show no significant change compared to Comparative Example 7, indicating that the high-dielectric-constant polypropylene prepared by the present invention has excellent stability and durability. The melt flow rate (MFR) of Example 1 is not significantly different from that of Comparative Example 7, indicating that the high-dielectric-constant polypropylene prepared by the present invention maintains high physical and mechanical strength even after aging.

[0265] 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 using acrylamide polar monomers of formula (I) and unsaturated carboxylic acid polar monomers of formula (II), 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） (II) In the formula, R1 and R2 are independently selected from hydrogen and C1 to C6 alkyl groups; The number-average molecular weight (Mn) of the activated macromolecular dielectric enhancer is 9000~17000; Based on a total mass of 100 parts of acrylamide polar monomers and unsaturated carboxylic acid polar monomers, the acrylamide polar monomers comprise 70-80 parts, the unsaturated carboxylic acid polar monomers comprise 20-30 parts, and the 1,3-butadiene comprises 3.0-5.0 parts; the amount of ethylene used is to maintain a reaction pressure of 35-45 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, The unsaturated carboxylic acid polar monomer is selected from one of acrylic acid, methacrylic acid, 2-ethylacrylic acid, 2-propylacrylic acid, and 2-n-butylacrylic acid.

4. The preparation method according to claim 1, wherein, Based on a total mass of 100 parts of the acrylamide polar monomer and the unsaturated carboxylic acid polar monomer, 0.5 to 0.7 parts of molecular weight regulator and 0.07 to 0.4 parts of initiator were also added during the free radical polymerization reaction.

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

6. The preparation method according to claim 4, wherein, The initiator is selected from one or more combinations of diacetyl peroxide, diisobutyryl peroxide, cumene hydroperoxide, diisobutyryl peroxide, and dibenzoyl peroxide.

7. The preparation method according to claim 1, wherein, The free radical polymerization reaction is carried out in a protective atmosphere and in a solvent; the reaction temperature of the free radical polymerization reaction is 80~90℃ and the time is 5.0~7.0 h.

8. 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 3.0 to 5.0 parts, and the amount of the alkylaluminoxane co-catalyst is 90 to 100 parts.

9. The preparation method according to claim 8, 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 dibromide nickel.

10. The preparation method according to claim 8, wherein, The alkylaluminoxane cocatalyst is methylaluminoxane or ethylaluminoxane.

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

12. 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 11 and propylene as raw materials.

13. The preparation method according to claim 12, 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. Based on 1 part by weight of the supported Ziegler-Natta catalyst, the mass of the reactive macromolecular dielectric enhancer is 4.0 to 7.0 parts, and the amount of propylene used is to maintain a reaction pressure of 20 to 30 MPa.

14. The preparation method according to claim 12, wherein, The polymerization reaction of the reactive macromolecular dielectric enhancer and propylene is carried out at a temperature of 80-90°C and a reaction time of 4.0-6.0 h.

15. The preparation method according to claim 12, 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 80~90℃ and 20~30 MPa for 4.0~6.0 h to obtain the polypropylene composite material.

16. The preparation method according to claim 13 or 15, 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.

17. The preparation method according to claim 16, 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.

18. A polypropylene composite material obtained by the preparation method according to any one of claims 12-17.

19. The polypropylene composite material according to claim 18, wherein, The dielectric constant of the polypropylene composite material is 4.3~4.

9.

20. The polypropylene composite material according to claim 18, wherein, The dielectric loss of the polypropylene composite material is (2.6~3.0) tgδ×10 4 .

21. The polypropylene composite material according to claim 18, wherein, The melt mass flow rate (MFR) of the polypropylene composite material is (4.3~7.0) g / 10 min.

22. The use of the polypropylene composite material according to any one of claims 18-21 in the preparation of film capacitors or lithium battery separators.

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