A high-performance polypropylene electrical film resistant to electrical breakdown and a preparation method thereof

Abstract

The application relates to the technical field of polypropylene electrical film, in particular to a high-performance polypropylene electrical film with electric breakdown resistance and a preparation method thereof. The application provides a preparation method of the high-performance polypropylene electrical film, wherein polypropylene powder, styrene, a crosslinking aid and a compatilizer are mixed, melt-extruded and granulated, and then subjected to heat pressing, cold pressing, bidirectional stretching, cooling and shaping, edge cutting and corona treatment to obtain the polypropylene electrical film; the crosslinking aid is prepared from maleic anhydride, 2,4,6-triaminotoluene and allyl isocyanate; and the compatilizer is obtained by reacting maleic anhydride and polypropylene. The polypropylene electrical film prepared by the application has good performance and combustion performance, high mechanical strength and strong electric breakdown resistance at high temperatures.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of polypropylene electrical film, in particular to a high-performance polypropylene electrical film resistant to electrical breakdown and a preparation method thereof. BACKGROUND

[0002] In recent years, with the gradual increase of human demand for clean energy, the proportion of renewable green energy such as wind energy and solar energy in power generation is becoming larger and larger. Capacitors, as key equipment for power storage, filtering and voltage stabilization, are widely used in various aspects of power systems. Compared with electrolytic capacitors, thin film capacitors have the advantages of high rated voltage, strong surge resistance and lightweight.

[0003] With the continuous development of new energy technology, the domestic lithium battery separator industry has also developed rapidly. Among many polyolefin materials, polypropylene has the advantages of light weight, cleanliness, high rigidity, good heat resistance, low dielectric loss coefficient, etc. After a two-way stretching process, it can be used to manufacture electrical films with small thickness and high mechanical properties, which are used in capacitor and lithium battery separator manufacturing. However, in a high-temperature environment, the breakdown field strength of polypropylene film decreases, and the lower breakdown field strength causes the polypropylene film to be prone to insulation breakdown, and the decomposition of heat produces gas, thereby causing capacitor bulging, explosion and other failures. Therefore, it is necessary to modify the existing technology. SUMMARY

[0004] The purpose of the present application is to provide a high-performance polypropylene electrical film resistant to electrical breakdown and a preparation method thereof to solve the problems raised in the background art.

[0005] In order to solve the above technical problems, the present application provides the following technical scheme: a high-performance polypropylene electrical film resistant to electrical breakdown and a preparation method thereof, comprising the following steps:

[0006] Step 1:

[0007] Weigh the polypropylene powder, diphenyl peroxide, styrene, crosslinking aid and compatibilizer, heat and react for 10-15 minutes, melt and plasticize to obtain a molten flowable melt. Filter the molten flowable melt to remove impurities and unmelted substances, and extrude and granulate;

[0008] Step 2:

[0009] After hot pressing the granules, cool and press to obtain a thin sheet;

[0010] Step 3:

[0011] The thin sheet is subjected to two-way stretching, and the film subjected to two-way stretching is subjected to cooling and setting, edge cutting and corona treatment in sequence to obtain a polypropylene electrical film.

[0012] Further, in step 1, the reaction temperature is 190-200℃.

[0013] Further, in step 1, the melt plasticizing temperature is 260-270℃.

[0014] Further, in step 1, the extrusion granulation temperature is 250-260℃.

[0015] Further, in step 1, the content of each component is 100-120 parts by weight of polypropylene powder, 0.03-0.05 parts by weight of dibenzoyl peroxide, 1-2 parts by weight of styrene, 3-4 parts by weight of crosslinking aid, and 1-2 parts by weight of compatibilizer.

[0016] Further, in step 1, the preparation method of the crosslinking aid is as follows: maleic anhydride and 2,4,6-triaminotoluene are dispersed in 1,4-dioxane, heated to 85-90℃ under nitrogen protection, and stirred for 2-3h, then cooled to 50-60℃, and allyl isocyanate is added for 1-2h, and 1,4-dioxane is removed by rotary evaporation, and the solid precipitate is washed with ethanol and vacuum dried.

[0017] Further, the molar ratio of maleic anhydride, 2,4,6-triaminotoluene, and allyl isocyanate is 1:1:2.

[0018] Further, in step 1, the preparation method of the compatibilizer is as follows: polypropylene powder and maleic anhydride are dispersed in xylene, heated and stirred to 120-130℃ under nitrogen protection, and dibenzoyl peroxide is added for 3-5h, and the product is precipitated with acetone and washed with water and dried.

[0019] Further, the amount of each component is 45-50 parts by weight of polypropylene powder, 5-7 parts by weight of maleic anhydride dispersed in xylene, and 0.01-0.015 parts by weight of dibenzoyl peroxide.

[0020] Further, in step 1, the preparation method of the polypropylene powder is as follows: CONSISTA catalyst, activator triethylaluminum, and external electron donor cyclohexylmethyl dimethoxysilane are added to the Unipol process circulating gas pipeline, and the reaction is carried out in the Unipol process reactor; wherein the molar ratio of activator triethylaluminum to aluminum / titanium of CONSISTA catalyst is (12-48):1; the molar ratio of cyclohexylmethyl dimethoxysilane to silicon / titanium of CONSISTA catalyst is (1-4):1; the reaction temperature during the polymerization stage is 70-75℃, and the isotacticity of the polypropylene is ≥98wt.%.

[0021] Further, in step 2, the hot-pressing temperature is 200-210 DEG C, the hot-pressing pressure is 10-15 MPa, and the hot-pressing time is 10-15 min; the cold-pressing temperature is 25-35 DEG C, the cold-pressing pressure is 10-15 MPa, and the cold-pressing time is 10-15 min.

[0022] Further, in step 2, the thickness of the sheet is 100-120 mu m.

[0023] Further, in step 3, the longitudinal stretching multiple is 3-5 times, the transverse stretching multiple is 5-10 times, and the stretching is carried out in two directions synchronously.

[0024] Further, in step 3, the thickness of the polypropylene electrical engineer film is 2-4 mu m.

[0025] Compared with the prior art, the present application has the beneficial effects that: the present application provides a preparation method of high-performance polypropylene electrical engineer film, specifically: polypropylene powder, styrene, crosslinking aid and compatibility agent are mixed, melt-extrusion granulation is carried out, and then hot-pressing, cold-pressing, two-way stretching, cooling and shaping, edge cutting and corona treatment are carried out to obtain the polypropylene electrical engineer film. The polypropylene electrical engineer film prepared by the present application has good performance and is not easy to burn, and has strong electric breakdown strength at high temperature.

[0026] The crosslinking aid is synthesized by reaction with maleic anhydride, 2,4,6-triaminotoluene and allyl isocyanate as raw materials. The crosslinking aid contains two unsaturated carbon-carbon double bonds, which can react with styrene monomers under the action of an initiator to prepare long-chain branched polypropylene. The long-chain branched structure can enhance the entanglement between polypropylene molecular chains, inhibit the thermal motion of polypropylene molecular chains at high temperature, reduce the influence of temperature on free volume, and improve the dielectric properties. Generally, the ash in polypropylene is ionized to generate carriers under the action of electric heating composite field, and the carrier migration causes the increase of conductance loss and the decrease of breakdown field strength. In the present application, styrene and crosslinking aid are both aromatic compounds, which can introduce deep traps on the long-chain branches to limit the carrier migration characteristics and thus realize the strengthening of the dielectric properties of the film; in addition, the benzene ring structure has strong electron affinity and stability (has a similar effect to voltage stabilization), and the polypropylene matrix after grafting the benzene ring is more likely to capture high-energy electrons, while inhibiting the destruction of high-energy electrons to polyolefin molecular chains, so the material has stronger electric breakdown resistance.

[0027] In addition, the application also prepares a compatilizer for improving the compatibility of each component. The compatilizer is obtained by the reaction of maleic anhydride and polypropylene. The compatilizer and the crosslinking aid in the application are both polar materials, which weakens the effect of interface polarization, so that it shows more excellent dielectric properties. The maleic anhydride in the compatilizer and the benzene ring produce a synergistic effect, which further increases the trap depth, obviously inhibits the accumulation of space charges in the polypropylene, improves the breakdown field strength, and thus inhibits the migration of charges, so that the addition of the compatilizer makes the polypropylene obtain good electrical properties and mechanical properties. DETAILED DESCRIPTION

[0028] Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the application.

[0029] The materials used in the application and sources: CONSISTA catalyst from the American GRACE company, model CONSISTA 602.

[0030] Embodiment 1: A high-performance polypropylene electrical film resistant to electric breakdown and a preparation method thereof, comprising the following steps:

[0031] Step 1:

[0032] Maleic anhydride, 2,4,6-triaminotoluene 2,4,6-triaminotoluene are dispersed in 1,4-dioxane, heated to 85 DEG C under nitrogen protection, heated to reflux and stirred for 2h, then cooled to 50 DEG C, and then allyl isocyanate is added and reacted for 1h, and then 1,4-dioxane is removed by rotary evaporation, and then the solid precipitate is washed with ethanol and vacuum dried to obtain a crosslinking agent; wherein the molar ratio of maleic anhydride, 2,4,6-triaminotoluene and allyl isocyanate is 1:1:2;

[0033] Step 2:

[0034] 50g of polypropylene powder and 5g of maleic anhydride are dispersed in xylene, heated and stirred under nitrogen protection to 120 DEG C, 0.013g of dibenzoyl peroxide is added and reacted for 3h, and then the product is precipitated with acetone and washed with water and dried to obtain a compatilizer;

[0035] Step 3:

[0036] S1: 120kg of polypropylene powder, 0.03kg of dibenzoyl peroxide, 1kg of styrene, 3kg of crosslinking aid and 1.5kg of compatilizer are mixed, heated to 190 DEG C and reacted for 10min, then heated to 260 DEG C and melt plasticized to obtain a molten and fluid melt; the molten and fluid melt is filtered to remove impurities and unmelted substances, and then extruded and granulated at 250 DEG C;

[0037] S2: hot-pressing the granules at 200℃, 10Mpa for 10min, cooling to 25℃, cold-pressing at 10MPa for 10min, to obtain a sheet with a thickness of 120μm;

[0038] S3: biaxially stretching the sheet, the longitudinal stretching ratio being 5 times, the transverse stretching ratio being 6 times, and the biaxial stretching being performed synchronously; and sequentially cooling, sizing, edge cutting and corona treating the biaxially stretched film to obtain a polypropylene electrical film with a thickness of 4μm.

[0039] The preparation method of the polypropylene powder comprises: adding CONSISTA catalyst, activator triethyl aluminum and external electron donor cyclohexyl methyl dimethoxysilane into a Unipol process circulating gas pipeline, and reacting in a Unipol process reactor; wherein the molar ratio of the activator triethyl aluminum to aluminum / titanium of the CONSISTA catalyst is 45:1; the molar ratio of the cyclohexyl methyl dimethoxysilane to silicon / titanium of the CONSISTA catalyst is 3.4:1; the polymerization stage reaction temperature is 70℃, and the isotacticity of the polypropylene is ≥98wt.%.

[0040] Embodiment 2: A high-performance polypropylene electrical film resistant to electric breakdown and a preparation method thereof, comprising the following steps:

[0041] Step 1:

[0042] Disperse maleic anhydride and 2,4,6-triaminotoluene in 1,4-dioxane, heat to 90℃ under nitrogen protection, and reflux and stir for 2.5h, then cool to 55℃, add allyl isocyanate and continue to react for 1.5h, remove 1,4-dioxane by rotary evaporation, wash the solid precipitate with ethanol, and vacuum dry to obtain a crosslinking aid; wherein the molar ratio of maleic anhydride, 2,4,6-triaminotoluene and allyl isocyanate is 1:1:2;

[0043] Step 2:

[0044] Disperse 50g of polypropylene powder and 5g of maleic anhydride in xylene, heat and stir under nitrogen protection until the temperature reaches 125℃, add 0.013g of dibenzoyl peroxide and react for 4h, precipitate the product with acetone, wash with clean water, and dry to obtain a compatibilizer;

[0045] Step 3:

[0046] S1: Mix 120kg of polypropylene powder, 0.03kg of dibenzoyl peroxide, 1.5kg of styrene, 3.5kg of crosslinking aid and 1.5kg of compatibilizer, heat to 195℃ and react for 12min, then heat to 265℃ for melt plasticizing to obtain a molten and fluid melt; filter the molten and fluid melt to remove impurities and unmelted substances in the melt, and extrude and granulate at 255℃.

[0047] S2: hot-pressing the granules at 205℃ and 13Mpa for 12min, cooling to 30℃, and cold-pressing at 12MPa for 14min to obtain a sheet with a thickness of 120μm;

[0048] S3: bidirectional stretching of the sheet, with a longitudinal stretching ratio of 5 and a transverse stretching ratio of 6, and the stretching being performed synchronously in both directions; and cooling, edge cutting and corona treatment of the bidirectionally stretched film to obtain a polypropylene electrical film with a thickness of 4μm.

[0049] The polypropylene powder is prepared by adding CONSISTA catalyst, activator triethylaluminum and external electron donor cyclohexyl methyl dimethoxysilane into the Unipol process circulating gas pipeline, and reacting in the Unipol process reactor; the molar ratio of the activator triethylaluminum to the aluminum / titanium of the CONSISTA catalyst is 45:1; the molar ratio of the cyclohexyl methyl dimethoxysilane to the silicon / titanium of the CONSISTA catalyst is 3.4:1; the polymerization stage reaction temperature is 72℃, and the isotacticity of the polypropylene is ≥98wt.%.

[0050] Example 3: a high-performance polypropylene electrical film resistant to electrical breakdown and a preparation method thereof, comprising the following steps:

[0051] Step 1:

[0052] Maleic anhydride and 2,4,6-triaminotoluene are dispersed in 1,4-dioxane, heated to 90℃ under nitrogen protection, and stirred for reflux reaction for 3h, then cooled to 60℃, and allyl isocyanate is added for further reaction for 2h, 1,4-dioxane is removed by rotary evaporation, the solid precipitate is washed with ethanol, and vacuum dried to obtain a crosslinking aid; the molar ratio of maleic anhydride, 2,4,6-triaminotoluene and allyl isocyanate is 1:1:2;

[0053] Step 2:

[0054] 50g of polypropylene powder and 5g of maleic anhydride are dispersed in xylene, heated and stirred under nitrogen protection to 130℃, 0.013g of dibenzoyl peroxide is added and reacted for 5h, the product is precipitated with acetone, washed with clean water and dried to obtain a compatibilizer;

[0055] Step 3:

[0056] S1: 120 kg of polypropylene powder, 0.03 kg of dibenzoyl peroxide, 2 kg of styrene, 4 kg of crosslinking aid, 1.5 kg of compatibilizer were mixed, heated to 200°C for 15 min, and then heated to 270°C for melt plasticizing to obtain a molten fluid melt; the molten fluid melt was filtered to remove impurities and unmelted substances in the melt, and then extruded and granulated at 260°C;

[0057] S2: The granules were hot-pressed at 210°C and 15 MPa for 15 min, cooled to 35°C, and then cold-pressed at 15 MPa for 15 min to obtain a sheet with a thickness of 120 μm;

[0058] S3: The sheet was bidirectionally stretched, with a longitudinal stretching ratio of 5 and a transverse stretching ratio of 6, and the bidirectional stretching was performed synchronously; the film after bidirectional stretching was sequentially subjected to cooling and setting, edge cutting, and corona treatment to obtain a polypropylene electrical film with a thickness of 4 μm.

[0059] The preparation method of the polypropylene powder is as follows: CONSISTA catalyst, activator triethylaluminum, and external electron donor cyclohexyl methyl dimethoxysilane are added to the Unipol process circulating gas pipeline, and then reacted in the Unipol process reactor; the molar ratio of the activator triethylaluminum to the aluminum / titanium of the CONSISTA catalyst is 45:1; the molar ratio of the cyclohexyl methyl dimethoxysilane to the silicon / titanium of the CONSISTA catalyst is 3.4:1; the reaction temperature during the polymerization stage is 70-75°C, and the isotacticity of the polypropylene is ≥98 wt.%.

[0060] Comparative Example 1: No crosslinking aid was added, and the other parameters were the same as in Example 1.

[0061] Step 1:

[0062] 50 g of polypropylene powder and 5 g of maleic anhydride were dispersed in xylene, heated and stirred under nitrogen protection to 120°C, 0.013 g of dibenzoyl peroxide was added, and reacted for 3 h; the product was precipitated with acetone, washed with clean water, and dried to obtain a compatibilizer;

[0063] Step 2:

[0064] S1: 120 kg of polypropylene powder, 0.03 kg of dibenzoyl peroxide, 1 kg of styrene, and 1.5 kg of compatibilizer were mixed, heated to 190°C for 10 min, and then heated to 260°C for melt plasticizing to obtain a molten fluid melt; the molten fluid melt was filtered to remove impurities and unmelted substances in the melt, and then extruded and granulated at 250°C;

[0065] S2: The granules were hot-pressed at 200°C and 10 MPa for 10 min, cooled to 25°C, and then cold-pressed at 10 MPa for 10 min to obtain a sheet with a thickness of 120 μm;

[0066] S3: bidirectional stretching of the sheet, longitudinal stretching ratio 5 times, transverse stretching ratio 6 times, bidirectional stretching is performed synchronously; the film after bidirectional stretching is sequentially subjected to cooling setting, edge cutting and corona treatment, to obtain a polypropylene electrical film with a thickness of 4 μm.

[0067] The preparation method of the polypropylene powder is: taking CONSISTA catalyst, activator triethylaluminum, external electron donor cyclohexyl methyl dimethoxysilane into the Unipol process circulating gas pipeline, and reacting in the Unipol process reactor; wherein the molar ratio of the activator triethylaluminum to the aluminum / titanium of the CONSISTA catalyst is 45:1; the molar ratio of the cyclohexyl methyl dimethoxysilane to the silicon / titanium of the CONSISTA catalyst is 3.4:1; the polymerization stage reaction temperature is 70℃, and the isotacticity of the polypropylene is ≥98wt.%.

[0068] Comparative Example 2: no benzene ring structure is introduced (melamine is used instead of 2,4,6-triaminotoluene to prepare the crosslinking aid, and no styrene is introduced), and the rest of the parameters are the same as those of Example 2.

[0069] Step 1:

[0070] Maleic anhydride and melamine are dispersed in 1,4-dioxane, heated to 90℃ under nitrogen protection, and stirred for reflux reaction for 2.5h, then cooled to 55℃, and allyl isocyanate is added for continuous reaction for 1.5h, and 1,4-dioxane is removed by rotary evaporation, and the solid precipitate is washed with ethanol and vacuum dried to obtain a crosslinking aid; wherein the molar ratio of maleic anhydride, melamine and allyl isocyanate is 1:1:2;

[0071] Step 2:

[0072] 50g of polypropylene powder and 5g of maleic anhydride are dispersed in xylene, heated and stirred under nitrogen protection to 125℃, 0.013g of dibenzoyl peroxide is added and reacted for 4h, and the product is precipitated with acetone and washed with clean water and dried to obtain a compatibilizer;

[0073] Step 3:

[0074] S1: 120kg of polypropylene powder, 0.03kg of dibenzoyl peroxide, 3.5kg of crosslinking aid, and 1.5kg of compatibilizer are mixed, heated to 195℃ and reacted for 12min, and then heated to 265℃ for melt plasticizing to obtain a molten and fluid melt; the molten and fluid melt is filtered to remove impurities and unmelted substances in the melt, and is extruded and granulated at 255℃;

[0075] S2: hot-pressing the granules at 205℃, 13Mpa for 12min, cooling to 30℃, cold-pressing at 12MPa for 14min, to obtain a sheet with a thickness of 120μm;

[0076] S3: biaxially stretching the sheet, the longitudinal stretching ratio being 5 times, the transverse stretching ratio being 6 times, and the biaxial stretching being performed synchronously; and sequentially cooling, sizing, edge cutting and corona treating the biaxially stretched film, to obtain a polypropylene electrical film with a thickness of 4μm.

[0077] The preparation method of the polypropylene powder is as follows: taking CONSISTA catalyst, activator triethyl aluminum and external electron donor cyclohexyl methyl dimethoxysilane into a Unipol process circulating gas pipeline, and reacting in a Unipol process reactor; wherein the molar ratio of the activator triethyl aluminum to aluminum / titanium of the CONSISTA catalyst is 45:1; the molar ratio of the cyclohexyl methyl dimethoxysilane to silicon / titanium of the CONSISTA catalyst is 3.4:1; the reaction temperature in the polymerization stage is 72℃, and the isotacticity of the polypropylene is ≥98wt.%.

[0078] Comparative Example 3: no compatilizer is added, and the other parameters are the same as those in Example 3.

[0079] Step 1:

[0080] Taking maleic anhydride and 2,4,6-triaminotoluene, dispersing them in 1,4-dioxane, and stirring under heating reflux at 90℃ for 3h, then cooling to 60℃, adding allyl isocyanate and continuing to react for 2h, removing 1,4-dioxane by rotary evaporation, washing the solid precipitate with ethanol, and vacuum drying to obtain a crosslinking aid; wherein the molar ratio of maleic anhydride, 2,4,6-triaminotoluene and allyl isocyanate is 1:1:2;

[0081] Step 2:

[0082] S1: taking 120kg of polypropylene powder, 0.03kg of dibenzoyl peroxide, 2kg of styrene, 4kg of crosslinking aid and 1.5kg of compatilizer, mixing them, heating to 200℃ and reacting for 15min, heating to 270℃ and melt plasticizing to obtain a molten and fluid melt; filtering the molten and fluid melt to remove impurities and unmelted substances in the melt, and extruding and granulating at 260℃;

[0083] S2: hot-pressing the granules at 210℃, 15Mpa for 15min, cooling to 35℃, cold-pressing at 15MPa for 15min, to obtain a sheet with a thickness of 120μm;

[0084] S3: The sheet is biaxially stretched, with a longitudinal stretching ratio of 5 times and a transverse stretching ratio of 6 times, and the biaxial stretching is performed simultaneously; the biaxially stretched film is sequentially cooled, shaped, trimmed, and corona treated to obtain a polypropylene electrical film with a thickness of 4 μm.

[0085] The polypropylene powder is prepared by adding a CONSISTA catalyst, an activator, triethylaluminum, and an external electron donor, cyclohexylmethyldimethoxysilane, to a Unipol process recycle gas line and reacting them in a Unipol process reactor. The molar ratio of aluminum to titanium in the activator, triethylaluminum, and CONSISTA catalyst is 45:1, and the molar ratio of silicon to titanium in the cyclohexylmethyldimethoxysilane and CONSISTA catalyst is 3.4:1. The polymerization temperature is 75°C, and the polypropylene isotacticity is ≥98 wt.%.

[0086] Experiment: The performance of the polypropylene electrical films prepared in Examples 1 to 3 and Comparative Examples 1 to 3 was tested.

[0087] Tensile performance test: The tensile strength and elongation at break of the samples were tested according to GB / T 12802.2-2004. Each group of samples was tested 5 times and the average value was calculated.

[0088] Dielectric strength test: Place the sample on a ball-plate electrode and apply voltage at a rate of 0.5 kV / s until the film breaks down. The test temperature is 100°C. Each group of samples is tested 5 times and the average value is calculated and recorded as the DC breakdown voltage.

[0089] The experimental results are shown in Table 1.

[0090] Table 1. Test results of various properties of polypropylene electrical film

[0091]

[0092] Conclusion: The data of Examples 1 to 3 show that the polypropylene electrical membrane prepared by the present invention has good performance. The data of Example 1 and Comparative Example 1 show that after the addition of a cross-linking aid, since the cross-linking aid contains two unsaturated carbon-carbon double bonds, it can be grafted together with styrene onto the polypropylene side chain to form a branched long chain, thereby improving the electrical breakdown resistance of the polypropylene electrical membrane at high temperatures. The data of Example 2 and Comparative Example 2 show that after the introduction of the benzene ring structure, the electronic energy band structure of the polypropylene matrix is ​​different. After the benzene ring structure is grafted onto the polypropylene, a deep trap site will be formed inside the polypropylene, thereby improving the breakdown performance. The data of Example 3 and Comparative Example 3 show that when a compatibilizer is added, since the compatibilizer and the cross-linking aid are polar, the grafting rate of styrene in polypropylene can be increased. At the same time, the two will also produce a synergistic effect, which increases the trap depth, thereby inhibiting the migration of charges, effectively hindering the accumulation of spatial charges in polypropylene, and improving the electrical breakdown strength.

[0093] Finally, it should be noted that the above only describes the preferred embodiments of the present application and is not intended to limit the present application. Although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art will appreciate that modifications can be made to the technical solutions described in the foregoing embodiments, or some of the technical features thereof can be replaced by equivalent features. Any modifications, equivalent replacements, improvements, and the like made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing an electrically shock resistant high performance polypropylene electrical film, characterized by: Comprising the following steps: Step 1: Take polypropylene powder, dibenzoyl peroxide, styrene, crosslinking aid, compatibilizer, mix, heat to 190~200℃ for 10~15min, heat to 260~270℃ melt plasticizing, get melt flow state melt; melt flow state melt is filtered, remove the impurities and unmelted in the melt, extruded and granulated at 250~260℃; Step 2: hot pressing, cooling and cold pressing to get sheet; Step 3: two-way stretching, cooling and setting, edge cutting and corona treatment to get polypropylene electrical film; In step 1, the content of each component is 100~120 parts by weight of polypropylene powder, 0.03~0.05 parts by weight of dibenzoyl peroxide, 1~2 parts by weight of styrene, 3~4 parts by weight of crosslinking aid, and 1~2 parts by weight of compatibilizer; The preparation method of the crosslinking aid is: take maleic anhydride and 2,4,6-triaminotoluene and disperse them in 1,4-dioxane, heat to 85~90℃ under nitrogen protection, heat reflux stirring for 2~3h, then cool to 50~60℃, add allyl isocyanate and continue to react for 1~2h, remove 1,4-dioxane by rotary evaporation, wash the solid precipitate with ethanol, and dry in vacuum; The molar ratio of maleic anhydride, 2,4,6-triaminotoluene and allyl isocyanate is 1:1:2; The preparation method of the compatibilizer is: disperse 45~50 parts by weight of polypropylene powder and 5~7 parts by weight of maleic anhydride in xylene, heat and stir to 120~130℃ under nitrogen protection, add 0.01~0.015 parts by weight of dibenzoyl peroxide and react for 3~5h, precipitate the product with acetone and wash with water, and dry; The preparation method of the polypropylene powder is: take CONSISTA catalyst, activator triethylaluminum, and external electron donor cyclohexyl methyl dimethoxy silane and add them to the Unipol process circulating gas pipeline, and react in the Unipol process reactor; the molar ratio of the activator triethylaluminum to the aluminum / titanium of the CONSISTA catalyst is (12~48):1; the molar ratio of the cyclohexyl methyl dimethoxy silane to the silicon / titanium of the CONSISTA catalyst is (1~4):1; the polymerization stage reaction temperature is 70~75℃, and the polypropylene isotacticity is ≥98wt.%.

2. The preparation method of the high-performance polypropylene electrical film resistant to electrical breakdown according to claim 1, characterized in that: In step 2, the hot pressing temperature is 200~210℃, the hot pressing pressure is 10~15Mpa, and the hot pressing time is 10~15min; the cold pressing temperature is 25~35℃, the cold pressing pressure is 10~15MPa, and the cold pressing time is 10~15min.

3. The preparation method of the high-performance polypropylene electrical film resistant to electrical breakdown according to claim 1, characterized in that: In step 2, the thickness of the sheet is 100~120μm.

4. The preparation method of the high-performance polypropylene electrical film resistant to electrical breakdown according to claim 1, characterized in that: In step 3, the longitudinal stretching multiple is 3~5 times, the transverse stretching multiple is 5~10 times, and the two-way stretching is carried out synchronously; the thickness of the polypropylene electrical film is 2~4μm.

5. The polypropylene electrical film prepared by the preparation method of any one of claims 1~4.

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