An organic small molecule grafted modified bopp film and a preparation method thereof

Abstract

The application discloses a kind of organic small molecule grafting modified BOPP film and preparation method thereof, belong to dielectric energy storage material preparation technical field.The application solves the technical problem that the energy storage density of existing dielectric energy storage material significantly decreases at high temperature.The application uses the mode of ultraviolet irradiation, grafts organic small molecule to BOPP film, so that the film has higher breakdown field strength and energy storage efficiency, while having lower leakage current density and loss factor.The acrylic grafting modified BOPP film prepared by the application reaches 593kV / mm at the breakdown field strength of 125 DEG C, the energy storage efficiency is 80% when the field strength is 500kV / mm, and the application of the application to dielectric capacitor can further improve the comprehensive performance of dielectric capacitor under high temperature condition.In addition, the application uses the mode of ultraviolet irradiation to prepare organic small molecule grafting BOPP film, has the advantages of simple process flow, environmental protection, pollution-free, low manufacturing cost, etc., and is suitable for industrial production.

Description

Technical Field

[0001] This invention relates to an organic small molecule grafted modified BOPP film and its preparation method, belonging to the field of dielectric energy storage material preparation technology. Background Technology

[0002] Polymer-based dielectric capacitors have broad application prospects in both military and civilian fields due to their excellent performance. With technological advancements and increasing voltage levels, higher requirements are being placed on the electrical insulation, mechanical properties, and heat resistance of insulating materials. Polypropylene, a polymer with a stable chemical structure and good electrical insulation, is often used as a dielectric energy storage material. Good energy storage performance is crucial for the energy storage medium of dielectric capacitors, and the significant decrease in energy density at high temperatures is a problem that needs to be addressed in the field of dielectric energy storage materials. Summary of the Invention

[0003] In order to solve the above-mentioned technical problems, the present invention provides an organic small molecule grafted modified BOPP film and its preparation method.

[0004] The technical solution of the present invention:

[0005] An organic small molecule grafted modified BOPP film, wherein the organic small molecule is grafted onto the polymer molecular chain of the BOPP film by ultraviolet light irradiation.

[0006] Further specifying, the organic small molecule is acrylic acid, methyl acrylate, butyl acrylate or methyl methacrylate.

[0007] The method for preparing the above-mentioned organic small molecule grafted modified BOPP film includes the following steps:

[0008] Step 1: Prepare benzophenone solution;

[0009] Benzophenone solid was added to acetone and stirred with a magnetic stirrer at room temperature to obtain a benzophenone solution.

[0010] Step 2: Pre-treat the BOPP film;

[0011] The BOPP film was immersed in acetone, dried, and then immersed in the benzophenone solution obtained in step one. The resulting film was then air-dried at room temperature.

[0012] Step 3: Prepare organic small molecule solutions;

[0013] Organic small molecules are mixed with acetone, and the mixture is stirred and sonicated to obtain a homogeneous organic small molecule solution.

[0014] Step 4: Grafting and modifying BOPP film;

[0015] The BOPP film pretreated in step two was laid flat in a petri dish, a certain amount of the organic small molecule solution obtained in step three was added, and the dish was placed under an ultraviolet light source for a certain period of time to obtain the organic small molecule grafted modified BOPP film.

[0016] Step 5: Post-processing of BOPP film modified with organic small molecules;

[0017] The organic small molecule grafted modified BOPP film obtained in step four was immersed in acetone, stirred at low speed for a certain period of time, then spread flat on a polyester film and heated to dry.

[0018] Further specified, in step one, the mass-to-volume ratio of benzophenone and acetone is 2g:100mL; and the mixture is stirred at 500-800r / min for 2h at room temperature.

[0019] Further specified, in step two, the size of the BOPP film is 2*5cm, the BOPP film is soaked in acetone for 10-30 minutes, and the drying temperature is 60℃.

[0020] Further specifying, in step two, the BOPP film is immersed in the benzophenone solution for 10–30 minutes.

[0021] Further specifying, the concentration of the organic small molecule solution in step three is 1–4 mol / L.

[0022] Further specifying, the stirring in step three is to stir at a speed of 1000-1300 r / min for 30 min, and the ultrasound is to ultrasound at a power of 560W for 10 min.

[0023] Further specifying, the volume of the organic small molecule solution added in step four is 2-4 mL, the irradiation time is 1-30 s, and the power of the ultraviolet light source is 3 kW.

[0024] Further specified, in step five, the stirring speed is 100 r / min and the stirring time is 5 min; the drying temperature is specified and the time is 4 to 6 h.

[0025] The present invention has the following beneficial effects:

[0026] This invention grafts small organic molecules onto BOPP films, resulting in films with high breakdown field strength and energy storage efficiency while exhibiting low leakage current density and loss factor. Applying these films to dielectric capacitors can further improve their overall energy storage performance. Furthermore, the grafted and modified BOPP films prepared by this invention exhibit excellent electrical properties at high temperatures. When the graft compound is acrylic acid, the modified BOPP film achieves a breakdown field strength of 578 kV / mm at 100°C and an energy storage efficiency of 80%. Applying this to dielectric capacitors further enhances their overall performance under high-temperature conditions. In addition, this invention utilizes ultraviolet irradiation to prepare the organic small molecule grafted BOPP film, which offers advantages such as a simple process, environmental friendliness, low production cost, and suitability for industrial production. Attached Figure Description

[0027] Figure 1 The infrared spectra of the BOPP films prepared in Examples 2-5 and the unmodified BOPP films are compared.

[0028] Figure 2 The infrared spectra of the BOPP films prepared in Examples 2, 6, and 7 are compared with those of the unmodified BOPP film.

[0029] Figure 3 This is a comparison chart of the energy storage characteristics of the BOPP films prepared in Examples 2, 6, and 7 and the unmodified BOPP films at 100°C.

[0030] Figure 4 The breakdown field strength is represented by the Weibull distribution diagram of the BOPP film prepared in Examples 4, 9, and 12 and the unmodified BOPP film.

[0031] Figure 5 The leakage current test curves of the grafted modified BOPP film and the unmodified BOPP film obtained in Examples 2, 6 and 7 are shown.

[0032] Figure 6 The electrical displacements of the grafted modified BOPP film and the unmodified BOPP film obtained in Example 7 are shown. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0034] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials, reagents, methods, and instruments used are all conventional materials, reagents, methods, and instruments in the art, and can be obtained commercially by those skilled in the art.

[0035] Example 1:

[0036] The steps for preparing the organic small molecule grafted BOPP film in this embodiment are as follows:

[0037] Step 1: Add benzophenone solid to acetone at a certain mass-to-volume ratio, and stir with a magnetic stirrer at room temperature for a certain time to obtain benzophenone solution.

[0038] Step 2: Immerse a BOPP film of a certain size in acetone for a certain period of time, dry the resulting film at a certain temperature and then immerse it in the solution obtained in Step 1 for a certain period of time. Allow the resulting film to air dry naturally at room temperature.

[0039] Step 3: Add a certain amount of acrylic acid to acetone, and the resulting mixture is stirred and sonicated to obtain a homogeneous solution.

[0040] Step 4: Spread the film obtained in Step 2 flat in a petri dish, add a certain amount of the solution obtained in Step 3, place the petri dish under an ultraviolet light source, and irradiate for a certain period of time to obtain an acrylic-grafted BOPP film.

[0041] Step 5: Immerse the film obtained in Step 4 in acetone and stir it with a magnetic stirrer at low speed for a certain period of time. Spread the resulting film flat on a polyester film and dry it at a certain temperature for a certain period of time.

[0042] Example 2:

[0043] The steps for preparing the organic small molecule grafted BOPP film (BOPP-AA for short) in this embodiment are as follows:

[0044] Step 1: Add solid benzophenone to acetone at a mass-to-volume ratio of 2g:1000ml, and stir at room temperature using a magnetic stirrer at 800r / min for 2 hours to obtain a benzophenone solution.

[0045] Step 2: Immerse a 2*5cm BOPP film in acetone for 30 minutes, dry the resulting film at 60℃ and immerse it in the solution obtained in Step 1 for 30 minutes, and then let the resulting film air dry at room temperature.

[0046] Step 3: Prepare a 2 mol / L acetone solution of acrylic acid. The resulting mixture is stirred and sonicated to obtain a homogeneous solution.

[0047] Step 4: Spread the film obtained in Step 2 flat in a petri dish, add 3 mL of the solution obtained in Step 3, place the petri dish under an ultraviolet light source, and irradiate for 15 s to obtain BOPP-AA.

[0048] Step 5: Immerse the film obtained in Step 4 in acetone and stir it with a magnetic stirrer at 100 r / min for 5 min. Spread the resulting film flat on a polyester film and dry it at 60℃ for 4 h.

[0049] Example 3:

[0050] The steps for preparing the organic small molecule grafted BOPP film (BOPP-MA) in this embodiment are as follows:

[0051] Step 1: Add benzophenone solid to acetone at a mass-to-volume ratio of 2g:1000ml, and stir at room temperature with a magnetic stirrer at 800r / min for 2 hours to obtain benzophenone solution.

[0052] Step 2: Immerse a 2*5cm BOPP film in acetone for 30 minutes, dry the resulting film at 60℃ and immerse it in the solution obtained in Step 1 for 30 minutes, and then let the resulting film air dry at room temperature.

[0053] Step 3: Prepare a 2 mol / L methyl acrylate solution in acetone. The resulting mixture is stirred and sonicated to obtain a homogeneous solution.

[0054] Step 4: Spread the film obtained in Step 2 flat in a petri dish, add 3 mL of the solution obtained in Step 3, place the petri dish under an ultraviolet light source, and irradiate for 15 s to obtain BOPP-MA.

[0055] Step 5: Immerse the film obtained in Step 4 in acetone and stir it with a magnetic stirrer at 100 r / min for 5 min. Spread the resulting film flat on a polyester film and dry it at 60℃ for 4 h.

[0056] Example 4:

[0057] The steps for preparing the organic small molecule grafted BOPP film (BOPP-BA for short) in this embodiment are as follows:

[0058] Step 1: Add benzophenone solid to acetone at a mass-to-volume ratio of 2g:1000ml, and stir at room temperature with a magnetic stirrer at 800r / min for 2 hours to obtain benzophenone solution.

[0059] Step 2: Immerse a 2*5cm BOPP film in acetone for 30 minutes, dry the resulting film at 60℃ and immerse it in the solution obtained in Step 1 for 30 minutes, and then let the resulting film air dry at room temperature.

[0060] Step 3: Prepare a 2 mol / L butyl acrylate solution in acetone. The resulting mixture is stirred and sonicated to obtain a homogeneous solution.

[0061] Step 4: Spread the film obtained in Step 2 flat in a petri dish, add 3 mL of the solution obtained in Step 3, place the petri dish under an ultraviolet light source, and irradiate for 15 s to obtain BOPP-BA.

[0062] Step 5: Immerse the film obtained in Step 4 in acetone and stir it with a magnetic stirrer at 100 r / min for 5 min. Spread the resulting film flat on a polyester film and dry it at 60℃ for 4 h.

[0063] Example 5:

[0064] The steps for preparing the organic small molecule grafted BOPP film (BOPP-MMA) in this embodiment are as follows:

[0065] Step 1: Add benzophenone solid to acetone at a mass-to-volume ratio of 2g:1000ml, and stir at room temperature with a magnetic stirrer at 800r / min for 2 hours to obtain benzophenone solution.

[0066] Step 2: Immerse a 2*5cm BOPP film in acetone for 30 minutes, dry the resulting film at 60℃ and immerse it in the solution obtained in Step 1 for 30 minutes, and then let the resulting film air dry at room temperature.

[0067] Step 3: Prepare a 2 mol / L methyl methacrylate solution in acetone. The resulting mixture is stirred and sonicated to obtain a homogeneous solution.

[0068] Step 4: Spread the film obtained in Step 2 flat in a petri dish, add 3 mL of the solution obtained in Step 3, place the petri dish under an ultraviolet light source, and irradiate for 15 s to obtain BOPP-MMA.

[0069] Step 5: Immerse the film obtained in Step 4 in acetone and stir it with a magnetic stirrer at 100 r / min for 5 min. Spread the resulting film flat on a polyester film and dry it at 60℃ for 4 h.

[0070] Example 6:

[0071] The steps for preparing the organic small molecule grafted BOPP film (BOPP-AA for short) in this embodiment are as follows:

[0072] Step 1: Add benzophenone solid to acetone at a mass-to-volume ratio of 2g:1000ml, and stir at room temperature with a magnetic stirrer at 800r / min for 2 hours to obtain benzophenone solution.

[0073] Step 2: Immerse a 2*5cm BOPP film in acetone for 30 minutes, dry the resulting film at 60℃ and immerse it in the solution obtained in Step 1 for 15 minutes, and then let the resulting film air dry at room temperature.

[0074] Step 3: Prepare a 2 mol / L acetone solution of acrylic acid. The resulting mixture is stirred and sonicated to obtain a homogeneous solution.

[0075] Step 4: Spread the film obtained in Step 2 flat in a petri dish, add 3 mL of the solution obtained in Step 3, place the petri dish under an ultraviolet light source, and irradiate for 30 s to obtain BOPP-AA.

[0076] Step 5: Immerse the film obtained in Step 4 in acetone and stir it with a magnetic stirrer at 100 r / min for 5 min. Spread the resulting film flat on a polyester film and dry it at 60℃ for 4 h.

[0077] Example 7:

[0078] The steps for preparing the organic small molecule grafted BOPP film (BOPP-AA for short) in this embodiment are as follows:

[0079] Step 1: Add benzophenone solid to acetone at a mass-to-volume ratio of 2g:1000ml, and stir at room temperature with a magnetic stirrer at 800r / min for 2 hours to obtain benzophenone solution.

[0080] Step 2: Immerse a 2*5cm BOPP film in acetone for 30 minutes, dry the resulting film at 60℃ and immerse it in the solution obtained in Step 1 for 30 minutes, and then let the resulting film air dry at room temperature.

[0081] Step 3: Prepare a 2 mol / L acetone solution of acrylic acid. The resulting mixture is stirred and sonicated to obtain a homogeneous solution.

[0082] Step 4: Spread the film obtained in Step 2 flat in a petri dish, add 3 mL of the solution obtained in Step 3, place the petri dish under an ultraviolet light source, and irradiate for 2 seconds to obtain an acrylic-grafted BOPP film.

[0083] Step 5: Immerse the film obtained in Step 4 in acetone and stir it with a magnetic stirrer at 100 r / min for 5 min. Spread the resulting film flat on a polyester film and dry it at 60℃ for 4 h.

[0084] Example 8:

[0085] The steps for preparing the organic small molecule grafted BOPP film (BOPP-MA) in this embodiment are as follows:

[0086] Step 1: Add benzophenone solid to acetone at a mass-to-volume ratio of 2g:1000ml, and stir at room temperature with a magnetic stirrer at 800r / min for 2 hours to obtain benzophenone solution.

[0087] Step 2: Immerse a 2*5cm BOPP film in acetone for 30 minutes, dry the resulting film at 60℃ and immerse it in the solution obtained in Step 1 for 15 minutes, and then let the resulting film air dry at room temperature.

[0088] Step 3: Prepare a 2 mol / L methyl acrylate solution in acetone. The resulting mixture is stirred and sonicated to obtain a homogeneous solution.

[0089] Step 4: Spread the film obtained in Step 2 flat in a petri dish, add 3 mL of the solution obtained in Step 3, place the petri dish under an ultraviolet light source, and irradiate for 30 s to obtain BOPP-MA.

[0090] Step 5: Immerse the film obtained in Step 4 in acetone and stir it with a magnetic stirrer at 100 r / min for 5 min. Spread the resulting film flat on a polyester film and dry it at 60℃ for 4 h.

[0091] Example 9:

[0092] The steps for preparing the organic small molecule grafted BOPP film (BOPP-BA for short) in this embodiment are as follows:

[0093] Step 1: Add benzophenone solid to acetone at a mass-to-volume ratio of 2g:1000ml, and stir at room temperature with a magnetic stirrer at 800r / min for 2 hours to obtain benzophenone solution.

[0094] Step 2: Immerse a 2*5cm BOPP film in acetone for 30 minutes, dry the resulting film at 60℃ and immerse it in the solution obtained in Step 1 for 15 minutes, and then let the resulting film air dry at room temperature.

[0095] Step 3: Prepare a 2 mol / L butyl acrylate solution in acetone. The resulting mixture is stirred and sonicated to obtain a homogeneous solution.

[0096] Step 4: Spread the film obtained in Step 2 flat in a petri dish, add 3 mL of the solution obtained in Step 3, place the petri dish under an ultraviolet light source, and irradiate for 30 s to obtain BOPP-BA.

[0097] Step 5: Immerse the film obtained in Step 4 in acetone and stir it with a magnetic stirrer at 100 r / min for 5 min. Spread the resulting film flat on a polyester film and dry it at 60℃ for 4 h.

[0098] Example 10:

[0099] The steps for preparing the organic small molecule grafted BOPP film (BOPP-MMA) in this embodiment are as follows:

[0100] Step 1: Add benzophenone solid to acetone at a mass-to-volume ratio of 2g:1000ml, and stir at room temperature with a magnetic stirrer at 800r / min for 2 hours to obtain benzophenone solution.

[0101] Step 2: Immerse a 2*5cm BOPP film in acetone for 30 minutes, dry the resulting film at 60℃ and immerse it in the solution obtained in Step 1 for 15 minutes, and then let the resulting film air dry at room temperature.

[0102] Step 3: Prepare a 2 mol / L methyl methacrylate solution in acetone. The resulting mixture is stirred and sonicated to obtain a homogeneous solution.

[0103] Step 4: Spread the film obtained in Step 2 flat in a petri dish, add 3 mL of the solution obtained in Step 3, place the petri dish under an ultraviolet light source, and irradiate for 30 s to obtain BOPP-MMA.

[0104] Step 5: Immerse the film obtained in Step 4 in acetone and stir it with a magnetic stirrer at 100 r / min for 5 min. Spread the resulting film flat on a polyester film and dry it at 60℃ for 4 h.

[0105] Example 11:

[0106] The steps for preparing the organic small molecule grafted BOPP film (BOPP-MA) in this embodiment are as follows:

[0107] Step 1: Add benzophenone solid to acetone at a mass-to-volume ratio of 2g:1000ml, and stir at room temperature with a magnetic stirrer at 800r / min for 2 hours to obtain benzophenone solution.

[0108] Step 2: Immerse a 2*5cm BOPP film in acetone for 30 minutes, dry the resulting film at 60℃ and immerse it in the solution obtained in Step 1 for 30 minutes, and then let the resulting film air dry at room temperature.

[0109] Step 3: Prepare a 2 mol / L methyl acrylate solution in acetone. The resulting mixture is stirred and sonicated to obtain a homogeneous solution.

[0110] Step 4: Spread the film obtained in Step 2 flat in a petri dish, add 3 mL of the solution obtained in Step 3, place the petri dish under an ultraviolet light source, and irradiate for 2 s to obtain BOPP-MA.

[0111] Step 5: Immerse the film obtained in Step 4 in acetone and stir it with a magnetic stirrer at 100 r / min for 5 min. Spread the resulting film flat on a polyester film and dry it at 60℃ for 4 h.

[0112] Example 12:

[0113] The steps for preparing the organic small molecule grafted BOPP film (BOPP-BA for short) in this embodiment are as follows:

[0114] Step 1: Add benzophenone solid to acetone at a mass-to-volume ratio of 2g:1000ml, and stir at room temperature with a magnetic stirrer at 800r / min for 2 hours to obtain benzophenone solution.

[0115] Step 2: Immerse a 2*5cm BOPP film in acetone for 30 minutes, dry the resulting film at 60℃ and immerse it in the solution obtained in Step 1 for 30 minutes, and then let the resulting film air dry at room temperature.

[0116] Step 3: Prepare a 2 mol / L butyl acrylate solution in acetone. The resulting mixture is stirred and sonicated to obtain a homogeneous solution.

[0117] Step 4: Spread the film obtained in Step 2 flat in a petri dish, add 3 mL of the solution obtained in Step 3, place the petri dish under an ultraviolet light source, and irradiate for 2 s to obtain BOPP-BA.

[0118] Step 5: Immerse the film obtained in Step 4 in acetone and stir it with a magnetic stirrer at 100 r / min for 5 min. Spread the resulting film flat on a polyester film and dry it at 60℃ for 4 h.

[0119] Example 13:

[0120] The steps for preparing the organic small molecule grafted BOPP film (BOPP-MMA) in this embodiment are as follows:

[0121] Step 1: Add benzophenone solid to acetone at a mass-to-volume ratio of 2g:1000ml, and stir at room temperature with a magnetic stirrer at 800r / min for 2 hours to obtain benzophenone solution.

[0122] Step 2: Immerse a 2*5cm BOPP film in acetone for 30 minutes, dry the resulting film at 60℃ and immerse it in the solution obtained in Step 1 for 30 minutes, and then let the resulting film air dry at room temperature.

[0123] Step 3: Prepare a 2 mol / L methyl methacrylate solution in acetone. The resulting mixture is stirred and sonicated to obtain a homogeneous solution.

[0124] Step 4: Spread the film obtained in Step 2 flat in a petri dish, add 3 mL of the solution obtained in Step 3, place the petri dish under an ultraviolet light source, and irradiate for 2 s to obtain BOPP-MMA.

[0125] Step 5: Immerse the film obtained in Step 4 in acetone and stir it with a magnetic stirrer at 100 r / min for 5 min. Spread the resulting film flat on a polyester film and dry it at 60℃ for 4 h.

[0126] Example 14:

[0127] The steps for preparing the organic small molecule grafted BOPP film (BOPP-AA for short) in this embodiment are as follows:

[0128] Step 1: Add benzophenone solid to acetone at a mass-to-volume ratio of 2g:1000ml, and stir at room temperature with a magnetic stirrer at 800r / min for 2 hours to obtain benzophenone solution.

[0129] Step 2: Immerse a 2*5cm BOPP film in acetone for 30 minutes, dry the resulting film at 60℃ and immerse it in the solution obtained in Step 1 for 30 minutes, and then let the resulting film air dry at room temperature.

[0130] Step 3: Prepare a 2 mol / L acetone solution of acrylic acid. The resulting mixture is stirred and sonicated to obtain a homogeneous solution.

[0131] Step 4: Spread the film obtained in Step 2 flat in a petri dish, add 3 mL of the solution obtained in Step 3, place the petri dish under an ultraviolet light source, and irradiate for 15 s to obtain BOPP-AA.

[0132] Step 5: Immerse the film obtained in Step 4 in acetone and stir it with a magnetic stirrer at 100 r / min for 5 min. Spread the resulting film flat on a polyester film and dry it at 60℃ for 4 h.

[0133] Example 15:

[0134] The steps for preparing the organic small molecule grafted BOPP film (BOPP-MA) in this embodiment are as follows:

[0135] Step 1: Add benzophenone solid to acetone at a mass-to-volume ratio of 2g:1000ml, and stir at room temperature with a magnetic stirrer at 800r / min for 2 hours to obtain benzophenone solution.

[0136] Step 2: Immerse a 2*5cm BOPP film in acetone for 30 minutes, dry the resulting film at 60℃ and immerse it in the solution obtained in Step 1 for 30 minutes, and then let the resulting film air dry at room temperature.

[0137] Step 3: Prepare a 2 mol / L methyl acrylate solution in acetone. The resulting mixture is stirred and sonicated to obtain a homogeneous solution.

[0138] Step 4: Spread the film obtained in Step 2 flat in a petri dish, add 3 mL of the solution obtained in Step 3, place the petri dish under an ultraviolet light source, and irradiate for 15 s to obtain BOPP-MA.

[0139] Step 5: Immerse the film obtained in Step 4 in acetone and stir it with a magnetic stirrer at 100 r / min for 5 min. Spread the resulting film flat on a polyester film and dry it at 60℃ for 4 h.

[0140] Example 16:

[0141] The steps for preparing the organic small molecule grafted BOPP film (BOPP-BA for short) in this embodiment are as follows:

[0142] Step 1: Add benzophenone solid to acetone at a mass-to-volume ratio of 2g:1000ml, and stir at room temperature with a magnetic stirrer at 800r / min for 2 hours to obtain benzophenone solution.

[0143] Step 2: Immerse a 2*5cm BOPP film in acetone for 30 minutes, dry the resulting film at 60℃ and immerse it in the solution obtained in Step 1 for 30 minutes, and then let the resulting film air dry at room temperature.

[0144] Step 3: Prepare a 2 mol / L butyl acrylate solution in acetone. The resulting mixture is stirred and sonicated to obtain a homogeneous solution.

[0145] Step 4: Spread the film obtained in Step 2 flat in a petri dish, add 3 mL of the solution obtained in Step 3, place the petri dish under an ultraviolet light source, and irradiate for 15 s to obtain BOPP-BA.

[0146] Step 5: Immerse the film obtained in Step 4 in acetone and stir it with a magnetic stirrer at 100 r / min for 5 min. Spread the resulting film flat on a polyester film and dry it at 60℃ for 4 h.

[0147] Example 17:

[0148] The steps for preparing the organic small molecule grafted BOPP film (BOPP-MMA) in this embodiment are as follows:

[0149] Step 1: Add benzophenone solid to acetone at a mass-to-volume ratio of 2g:1000ml, and stir at room temperature with a magnetic stirrer at 800r / min for 2 hours to obtain benzophenone solution.

[0150] Step 2: Immerse a 2*5cm BOPP film in acetone for 30 minutes, dry the resulting film at 60℃ and immerse it in the solution obtained in Step 1 for 30 minutes, and then let the resulting film air dry at room temperature.

[0151] Step 3: Prepare a 2 mol / L methyl methacrylate solution in acetone. The resulting mixture is stirred and sonicated to obtain a homogeneous solution.

[0152] Step 4: Spread the film obtained in Step 2 flat in a petri dish, add 3 mL of the solution obtained in Step 3, place the petri dish under an ultraviolet light source, and irradiate for 15 s to obtain BOPP-MMA.

[0153] Step 5: Immerse the film obtained in Step 4 in acetone and stir it with a magnetic stirrer at 100 r / min for 5 min. Spread the resulting film flat on a polyester film and dry it at 60℃ for 4 h.

[0154] Example 18:

[0155] The steps for preparing the organic small molecule grafted BOPP film (BOPP-MMA) in this embodiment are as follows:

[0156] Step 1: Add benzophenone solid to acetone at a mass-to-volume ratio of 2g:1000ml, and stir at room temperature with a magnetic stirrer at 800r / min for 2 hours to obtain benzophenone solution.

[0157] Step 2: Immerse a 2*5cm BOPP film in acetone for 30 minutes, dry the resulting film at 60℃ and immerse it in the solution obtained in Step 1 for 30 minutes, and then let the resulting film air dry at room temperature.

[0158] Step 3: Prepare a 2 mol / L methyl methacrylate solution in acetone. The resulting mixture is stirred and sonicated to obtain a homogeneous solution.

[0159] Step 4: Spread the film obtained in Step 2 flat in a petri dish, add 3 mL of the solution obtained in Step 3, place the petri dish under an ultraviolet light source, and irradiate for 15 s to obtain BOPP-MMA.

[0160] Step 5: Immerse the film obtained in Step 4 in acetone and stir it with a magnetic stirrer at 100 r / min for 5 min. Spread the resulting film flat on a polyester film and dry it at 60℃ for 4 h.

[0161] The grafted modified BOPP film obtained above was characterized in structure and analyzed in performance:

[0162] (1) Infrared spectroscopy tests were performed on the grafted modified BOPP films and the unmodified BOPP films obtained in Examples 2-5. The comparison curves are shown below. Figure 1 As shown, by Figure 1 It can be seen that after grafting different small molecules onto BOPP, the infrared absorption peak is at 1740 cm⁻¹. -1 A small number of C=O absorption peaks appear on the left and right sides.

[0163] (2) Infrared spectroscopy tests were performed on the grafted modified BOPP films and unmodified BOPP films obtained in Examples 2, 6, and 7. The infrared spectral curves of BOPP films with different amounts of acrylic acid grafting were compared, as shown below. Figure 2 As shown, when the ultraviolet irradiation time is 2, 15, and 30 seconds, the carbonyl absorption peak is enhanced and the amount of acrylic acid grafted increases with the increase of irradiation time.

[0164] (3) The energy storage characteristics of the grafted modified BOPP films and the unmodified BOPP films obtained in Examples 2, 6, and 7 were tested at 100°C. The energy storage characteristics of BOPP films with different amounts of acrylic acid grafting at 125°C were compared. Figure 3 As shown, when the ultraviolet irradiation time is 2, 15, and 30 seconds, the energy storage efficiency of the acrylic-grafted BOPP material is improved by about 10%.

[0165] (4) Breakdown tests were conducted on the grafted modified BOPP films and unmodified BOPP films obtained in Examples 4, 9, and 12. The breakdown performance of BOPP films with different butyl acrylate grafting amounts was compared. The Weibull distribution diagram of the breakdown field strength at 125°C is shown below. Figure 4 As shown, when the ultraviolet irradiation time is 2, 15, and 30 seconds, the grafting amount of butyl acrylate increases, and the breakdown field strength of BOPP-BA increases accordingly. When the irradiation time is 30 seconds, the breakdown field strength increases to 593 kV / mm.

[0166] (5) The leakage current of the grafted modified BOPP film and the unmodified BOPP film obtained in Examples 2, 6, and 7 at 125°C was compared, and the results are as follows: Figure 5 As shown, the leakage current of acrylic-grafted BOPP materials decreased when the ultraviolet irradiation time was 2, 15, and 30 seconds.

[0167] (6) Comparing the electrical displacement of the grafted modified BOPP film and the unmodified BOPP film obtained in Example 7 at 125°C, such as... Figure 6 As shown, when the ultraviolet irradiation time is 2 seconds, the electrical displacement of the acrylic-grafted BOPP material increases slightly.

Claims

1. A method for improving the breakdown field strength of BOPP films through organic small molecule grafting modification, characterized in that, Organic small molecules are grafted onto the polymer molecular chains of BOPP films using ultraviolet light irradiation; the organic small molecules are butyl acrylate. The method includes the following steps: Step 1: Prepare benzophenone solution; Benzophenone solid was added to acetone at a mass-to-volume ratio of 2g:1000ml, and stirred at room temperature with a magnetic stirrer at a speed of 800r / min for 2h to obtain a benzophenone solution. Step 2: Pre-treat the BOPP film; The BOPP film was immersed in acetone for 30 minutes, dried at 60°C, and then immersed in the benzophenone solution obtained in step one for 15 minutes. The resulting film was then air-dried at room temperature. Step 3: Prepare organic small molecule solutions; Butyl acrylate and acetone were mixed, and the mixture was stirred and sonicated to obtain a homogeneous 2 mol / L organic small molecule solution. Step 4: Grafting and modifying BOPP film; The BOPP film pretreated in step two was laid flat in a petri dish, 3 mL of the organic small molecule solution obtained in step three was added, and the dish was placed under a UV light source for irradiation for 30 s to obtain the organic small molecule grafted modified BOPP film. Step 5: Post-processing of BOPP film modified with organic small molecules; The organic small molecule grafted modified BOPP film obtained in step four was immersed in acetone, stirred at a low speed of 100 r / min for 5 min, then spread evenly on a polyester film and dried at 60℃ for 4 h.

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