A method for modifying polymer film by irradiating with an excimer deep ultraviolet light source

Abstract

The present invention discloses a method for modifying a polymer film by irradiating an excimer deep ultraviolet light source. A roll of polymer film is fixed to one end of an automatic film winding machine. The film is sequentially cleaned with distilled water and anhydrous ethanol, dried in a dryer, irradiated with an excimer deep ultraviolet light source, and then wound to the other end of the automatic film winding machine to complete the modification. The breakdown strength, discharge energy density, and charge-discharge efficiency of the modified polymer film at room temperature and high temperature are significantly improved. The modification method of the present invention can be completed in the air, is convenient and fast, has extremely low cost, and is pollution-free. It is an efficient modification method that can match the commercial production of polymer films.

Description

Technical Field

[0001] The invention belongs to the field of dielectric energy storage material preparation equipment and preparation technology, and specifically relates to a method for irradiating a modified polymer film with a quasi-molecular deep ultraviolet light source. Background Art

[0002] Polymer films such as biaxially oriented polypropylene (BOPP), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), etc., are efficient energy storage materials and important insulating materials used in power electronic energy storage devices. Existing polymer energy storage media are difficult to combine energy storage and high temperature resistance. For example, BOPP film has a high breakdown strength, and the breakdown strength at room temperature can reach 700MV / m, but BOPP film can only operate continuously at a maximum of 80°C. When the temperature is greater than 105°C, the energy storage performance will drop sharply until it is destroyed because the conduction loss will increase exponentially with the increase in temperature. Polyimide (PI) film has excellent high temperature resistance and can work at temperatures as high as 400°C, but its discharge energy efficiency at room temperature is much lower than that of BOPP film.

[0003] In order to improve the breakdown strength, energy storage, high temperature resistance, tensile strength and other properties of polymer films so that they can adapt to the needs of different occasions, relevant researchers have carried out a lot of research on polymer film modification.

[0004] Chinese patent application Cn202310527622.9 (A UV irradiation device and its application in the preparation of high temperature resistant capacitor film) discloses a method for UV irradiation modification of high temperature resistant capacitor film, which uses a winding device to control the movement of BOPP film, and after being soaked in a photoinitiator immersion structure and grafting solution, microwave drying and UV irradiation treatment are performed to obtain the grafted modified BOPP film. The breakdown field strength at 125°C reaches 593kV / mm, and when the field strength is 500kV / mm, the energy storage efficiency is 80%, which improves the temperature resistance of the capacitor film, but it uses initiator solution immersion grafting, microwave drying, UV irradiation and other means, the process flow is relatively complicated and the cost is high.

[0005] The Chinese patent application "Anti-aging BOPP film, preparation method and application thereof" (patent number: ZL202111088315.2) discloses an anti-aging BOPP film, preparation method and application thereof. First, antioxidant modified graphene is obtained by grafting graphene with an antioxidant, and then the modified graphene is blended and extruded with polypropylene, and a BOPP film is obtained by biaxial stretching. The obtained BOPP film has good anti-aging properties and can be applied to the field of capacitor technology. However, the graphene is obtained by oxidative grafting reaction of antioxidants on the raw materials, which is a chemical modification, so there is a problem of cumbersome operation.

[0006] The Chinese patent application "A weather-resistant flame-retardant PE film and its preparation method" (patent number: ZL202211675926.1) discloses a weather-resistant flame-retardant PE film and its preparation method. The preparation method is briefly described as making polyethylene resin, end-hydroxyl functionalized hyperbranched polyethylene, graft-modified high-density polyethylene, copolymer resin, filler, and antioxidant through raw material copolymerization reaction. The weather-resistant flame-retardant PE film has good weather resistance and flame retardancy, good mechanical properties, and sufficient barrier effect against oxygen and water vapor, but the raw materials of the synthetic film are chemically modified, and there is a problem of complex process flow.

[0007] The Chinese patent application "A solid-state chemically modified ultra-thin PET film and its preparation method" (application number: 202310951240.9) discloses a solid-state chemically modified ultra-thin PET film and its preparation method. The method first reacts PET with butenedioic acid to obtain a modified PET film, and then coats the modified PET film with a polythiol solution, and then irradiates it with deep ultraviolet light to obtain a solid-state chemically modified ultra-thin PET film. The haze of PET is significantly reduced by thiol modification, thereby improving the application of the film in the optical field, but it combines chemical modification and light modification, and the method is relatively complicated.

[0008] The common feature of the above modification methods is that they chemically modify the film or the raw materials used to prepare the film, and coat other modified materials on the surface of the film. The operation is relatively complicated and difficult to match commercial production. In contrast, photomodification, as a rarely used film modification method, has the advantages of being simple, fast, pollution-free, and easy to mass produce, and is worthy of in-depth research.

[0009] Existing polymer film preparation and modification technologies all use chemical copolymerization to make the modified raw materials and then undergo a series of process flows, or soak and mix with other drugs on the existing film substrate and then undergo a series of oxidation and substitution reactions. Chemical reaction modification has the problem of cumbersome operation due to its demanding reaction conditions and the need for strict control of the production process. Summary of the invention

[0010] In order to solve the above technical problems, the present invention provides a method for modifying polymer films by irradiating an excimer deep ultraviolet light source. The method uses an excimer deep ultraviolet light source with a specific wavelength to clean, dry and irradiate the polymer film in an airy, dust-free and room temperature environment to complete the modification. The method is simple to operate, extremely low in cost and pollution-free. It is an efficient modification method that can match the commercial production of polymer films.

[0011] In order to achieve the above object, the present invention adopts the following technical scheme:

[0012] A method for modifying a polymer film by irradiating an excimer deep ultraviolet light source comprises: fixing a roll of polymer film to one end of an automatic film winding machine, using a movable wheel shaft of the automatic film winding machine to change the winding path of the polymer film so that the polymer film passes through a distilled water container, an anhydrous ethanol container, a drying machine, and an excimer deep ultraviolet light source in sequence; after the automatic film winding machine is turned on, the polymer film is washed, dried, and ultraviolet-irradiated, and then wound to the other end of the automatic film winding machine, thereby completing the modification.

[0013] Furthermore, the polymer film includes BOPP, PET, and PEN films.

[0014] Furthermore, the excimer deep ultraviolet light source is a KrCl excimer lamp with a wavelength of 222nm or a Xe2 excimer lamp with a wavelength of 172nm, a power of 1-200W, and includes a lamp holder.

[0015] Furthermore, the length of the lamp tube of the excimer deep ultraviolet light source is longer than the width of the polymer film.

[0016] Furthermore, there are two excimer deep ultraviolet light sources, which are fixed to the upper and lower sides of the automatic film winding machine through lamp holders. The distance between the two excimer deep ultraviolet light sources and the height of the lamp holders are adjustable to ensure that the polymer film can pass through the gap between the two excimer deep ultraviolet light sources.

[0017] Furthermore, the lamp tube direction of the excimer deep ultraviolet light source is perpendicular to the winding direction of the polymer film and parallel to the surface of the polymer film.

[0018] Furthermore, the polymer film passes slowly and uniformly through the gap between two excimer deep ultraviolet light sources at a speed of 0.1-10 mm / s.

[0019] Furthermore, the temperature of the drying machine is controlled between 40-60°C.

[0020] Furthermore, both ends of the lamp tube of the excimer deep ultraviolet light source are at the same height as the polymer film.

[0021] Beneficial effects:

[0022] The present invention provides a method for modifying polymer films by ultraviolet irradiation with an excimer lamp. Compared with the currently commonly used chemical modification method, the present invention adopts a light modification method, which is simple to operate, extremely low in cost and pollution-free. It is an efficient modification method that can match the commercial production of polymer films. The discharge energy density, charge and discharge efficiency, and breakdown strength of the modified polymer film at room temperature and high temperature are significantly improved.

[0023] The modification method proposed in the present invention can be used for BOPP, PET, PEN and other polymer films, and has a wide range of practical value. For example, after the commercial BOPP film is modified by irradiation with a KrCl 222nm excimer deep ultraviolet light source, the breakdown voltage is increased from 694V / μm to 811V / μm at room temperature; and from 428V / μm to 651V / μm at 120°C. The discharge energy density is increased from 4MJ / m 3 Increased to 6.5MJ / m 3 (efficiency greater than 95%), 1.55MJ / m at 120°C 3 Increased to 2.1MJ / m 3 (Efficiency greater than 90%). BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The schematic diagram of the method for irradiating and modifying a polymer film with an excimer deep ultraviolet light source of the present invention;

[0025] Figure 2a , Figure 2b is the DEloop diagram before and after modification by excimer deep ultraviolet light source irradiation; Figure 2a Before modification, Figure 2b After modification. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0027] The components and materials involved in the method for modifying a polymer film by irradiating an excimer deep ultraviolet light source of the present invention include an excimer deep ultraviolet light source, a polymer film, an automatic film winding machine, a distilled water container, an anhydrous ethanol container, and a drying machine.

[0028] Preferably, the excimer deep ultraviolet light source is a KrCl excimer lamp with a wavelength of 222nm or a Xe2 excimer lamp with a wavelength of 172nm, a power of 1-200W, a lamp tube of 12cm in length and 2cm in width, including a lamp holder;

[0029] Preferably, the polymer film is a commercial BOPP, PET, or PEN film with a specification of 2-20 μm and a film width of 10 cm;

[0030] Preferably, distilled water and anhydrous ethanol are placed in glass containers.

[0031] Before irradiation, the polymer film needs to be soaked and cleaned with distilled water and anhydrous ethanol to remove dust, salt and lipid impurities adsorbed on the surface during material transportation and operation.

[0032] Preferably, the excimer deep ultraviolet light source is a specially processed and customized product, and the length of the lamp tube is adapted to the width of the polymer film and is slightly longer than the width of the polymer film, thereby ensuring that the polymer film is irradiated without dead angles.

[0033] Preferably, the automatic film winding machine is a multi-axle structure, used for winding and directional conveying of polymer films.

[0034] Preferably, the automatic film winding machine comprises a left axle, a right axle and a middle movable axle. Two excimer deep ultraviolet light sources are fixed to the automatic film winding machine through a lamp holder, and the distance and height of the two excimer deep ultraviolet light sources can be adjusted through the lamp holder to ensure that the polymer film passes through the gap between the two excimer deep ultraviolet light sources.

[0035] The principle of the present invention is: the photon energy in deep ultraviolet light is relatively high, which breaks the oxygen molecule bonds in the air to form oxygen atoms or active oxygen groups. When the polymer film is irradiated with deep ultraviolet light, the oxygen atoms and active oxygen groups will destroy the molecular chains in the polymer, break the CC and CH bonds therein, and realize the grafting of oxygen atoms and the cross-linking of polymer molecular chains. After cross-linking, the polymer molecular chains gradually form a network structure. Compared with the chain structure, the network structure is more solid and has better high temperature resistance. After the oxygen atom grafting, the polarity of the oxygen-containing part in the structure of the polymer molecule increases, forming a shallow charge trap, and the electron capture ability is enhanced, so it has a higher discharge energy density. The BOPP film irradiated by deep ultraviolet light has a higher discharge energy density, charge and discharge efficiency, and breakdown strength at room temperature and high temperature.

[0036] like Figure 1 As shown, a method for irradiating a polymer film with an excimer deep ultraviolet light source of the present invention comprises the following steps:

[0037] S1. Fix the lamp holder of the excimer deep ultraviolet light source on the automatic film winding machine, install a roll of polymer film on the left axle, and use the movable axle on the automatic film winding machine to make the polymer film pass through the distilled water container, the anhydrous ethanol container, the dryer and the two excimer deep ultraviolet light sources in turn. After passing the polymer film through the middle of the two excimer deep ultraviolet light sources, fix it on the right axle. Adjust the excimer deep ultraviolet light source so that the direction of the lamp tube is perpendicular to the winding direction of the polymer film and parallel to the surface of the polymer film. After the distance between the two excimer deep ultraviolet light sources and the polymer film is 0.5-10cm, fix the excimer deep ultraviolet light source;

[0038] S2. Turn on the automatic film winding machine to allow the polymer film to pass slowly and evenly through the gap between the distilled water container, the anhydrous ethanol container, the dryer and the two excimer deep ultraviolet light sources at a speed of 0.1-10 mm / s.

[0039] The present invention can be carried out in an air-containing, dust-free, room temperature environment, and dust-free gloves need to be worn during operation to avoid contamination of the polymer film.

[0040] Preferably, the temperature of the drying machine should be controlled between 40-60°C to ensure that the drying is completed without burning the film;

[0041] Preferably, the lamp tube of the excimer deep ultraviolet light source needs to be perpendicular to the film winding direction and parallel to the film surface to ensure that the film is uniformly irradiated;

[0042] Preferably, the length of the lamp tube of the excimer deep ultraviolet light source should be greater than the width of the polymer film to ensure that there is no irradiation dead angle;

[0043] The performance of the polymer film treated by the present invention was tested, and the polymer film was a BOPP film.

[0044] 1. Breakdown voltage test: After BOPP film is modified by irradiation with KrCl 222nm excimer deep ultraviolet light source, the breakdown voltage is increased from 694V to 811V / μm at room temperature; from 609V / μm to 724V / μm at 85℃; and from 428V / μm to 651V / μm at 120℃.

[0045] 2. Discharge energy density test: The discharge energy density at room temperature is 4MJ / m 3 Increased to 6.5MJ / m 3 (efficiency greater than 95%); 2.0MJ / m at 85°C 3 Increased to 3.2MJ / m 3 (efficiency greater than 95%); 1.55MJ / m at 120°C 3 Increased to 2.1MJ / m 3 (Efficiency greater than 90%). Figure 2a , Figure 2b By comparison, it can be seen that the area surrounded by the curve becomes smaller after the deep ultraviolet light source is modified, which proves that the charging and discharging efficiency is improved.

[0046] The method for modifying a polymer film by irradiating an excimer deep ultraviolet light source disclosed in the present invention is applicable to excimer lamps of any model, power and wavelength, except that excimer lamps of different powers and wavelengths have different modification efficiencies.

[0047] The method and principle of modifying polymer films by irradiating an excimer deep ultraviolet light source disclosed in the present invention are applicable to BOPP, PET and PEN films.

[0048] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for modifying a polymer film by irradiating an excimer deep ultraviolet light source, characterized in that: A roll of polymer film is fixed to one end of an automatic film winding machine, and a movable wheel shaft of the automatic film winding machine is used to change the winding path of the polymer film so that the polymer film passes through a distilled water container, an anhydrous ethanol container, a drying machine in sequence, and then passes through an excimer deep ultraviolet light source; after the automatic film winding machine is turned on, the polymer film is washed, dried, and ultraviolet-irradiated, and then wound to the other end of the automatic film winding machine, thus completing the modification; the length of the lamp tube of the excimer deep ultraviolet light source is greater than the width of the polymer film; the excimer deep ultraviolet light source is a KrCl excimer lamp with a wavelength of 222 nm, a power of 1-200 W, a lamp tube length of 5-100 cm, and a diameter of 1-5 cm; the polymer film is washed, dried, and irradiated in an environment containing air.

2. The method for modifying a polymer film by irradiating an excimer deep ultraviolet light source according to claim 1, characterized in that: The polymer film is a BOPP film, a PET film or a PEN film.

3. The method for modifying a polymer film by irradiating an excimer deep ultraviolet light source according to claim 1, characterized in that: The excimer deep ultraviolet light source includes a lamp holder.

4. The method for modifying a polymer film by irradiating an excimer deep ultraviolet light source according to claim 1, characterized in that: There are two excimer deep ultraviolet light sources, which are fixed to the upper and lower sides of the film through lamp holders. The height and spacing of the two excimer deep ultraviolet light sources can be adjusted through the lamp holder to ensure that the polymer film passes through the gap between the two excimer deep ultraviolet light sources.

5. The method for modifying a polymer film by irradiating an excimer deep ultraviolet light source according to claim 1, characterized in that: The axial direction of the lamp tube of the excimer deep ultraviolet light source is perpendicular to the winding direction of the polymer film and parallel to the surface of the polymer film.

6. The method for modifying a polymer film by irradiating an excimer deep ultraviolet light source according to claim 4, characterized in that: The polymer film passes slowly and uniformly through the gap between two excimer deep ultraviolet light sources at a speed of 0.1-10 mm / s.

7. The method for modifying a polymer film by irradiating an excimer deep ultraviolet light source according to claim 1, characterized in that: The temperature of the drying machine is controlled between 40-60° C., which can ensure that the drying is completed without burning the film.

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