A slot insulation material for a low-altitude aircraft motor and a preparation method thereof

Abstract

The application belongs to the field of electrical insulating materials, and discloses a slot insulating material for a low-altitude aircraft motor and a preparation method thereof. The slot insulating material for the low-altitude aircraft motor comprises, from top to bottom, a first insulating paper layer, a film layer and a second insulating paper layer; the first insulating paper layer and the second insulating paper layer are each independently selected from aramid fiber paper or polyaryl sulfone fiber paper; the film layer is selected from one of polyphenylene sulfide film, polyester film, polynaphthalene ester film, polyether ether ketone film or polyetherimide film; wherein, there is no independent adhesive layer between the first insulating paper layer, the film layer and the second insulating paper layer, the first insulating paper layer and the second insulating paper layer are directly combined on the upper and lower surfaces of the film layer through hot pressing, forming a three-layer glue-free composite structure of insulating paper-insulating film-insulating paper, and fundamentally solving the engineering problem that the glue-free composite slot insulating material is prone to paper breakage.

Description

Technical Field

[0001] This invention relates to the field of electrical insulation materials, specifically to a slot insulation material for motors of low-altitude aircraft and its preparation method. Background Technology

[0002] Low-altitude aircraft (including electric vertical takeoff and landing aircraft (eVTOL) and drones) place stringent requirements on motor slot insulation materials: they must meet performance requirements such as high temperature resistance, corona resistance, vibration resistance, and lightweight. A three-layer composite slot insulation material consisting of insulating paper-insulating film-insulating paper is one of the mainstream technologies for motor slot insulation in low-altitude aircraft.

[0003] "Glue-free lamination" refers to the direct bonding of the insulating paper layer and the insulating film layer through heat pressing, without the need for a separate adhesive layer. Traditional adhesive-based lamination structures consist of five layers (insulating paper layer - adhesive layer - resin base film layer - adhesive layer - insulating paper layer). The adhesive layer has inherent limitations in terms of thickness, heat resistance, and oil resistance. Glue-free lamination eliminates the performance bottlenecks caused by adhesives, achieving thinner composite thicknesses, higher thermal conductivity, higher heat resistance ratings, and better long-term reliability.

[0004] Following hot-pressing lamination, a recrystallization heat treatment provides sufficient energy to the amorphous polymer chains or fibers, allowing them to rearrange into the crystal lattice, increasing the material's crystallinity and thus improving the mechanical and electrical properties of the slot insulation material. Adhesive-free lamination uses a direct hot-pressing bonding process, reducing adhesive coating and drying steps compared to adhesive-based lamination, resulting in a shorter process route. From an environmental perspective, adhesive-based lamination uses organic adhesives that may release volatile organic compounds during production, while adhesive-free lamination uses no organic adhesives at all, making the production process cleaner and aligning with green manufacturing trends. Summary of the Invention

[0005] The purpose of this invention is to provide a slot insulation material for low-altitude aircraft motors and its preparation method, so as to solve the technical problems of existing low-altitude aircraft motor slot insulation materials, which are limited in heat resistance, have large total thickness, insufficient long-term reliability (adhesive thermal aging, poor oil resistance) and complex production process due to the use of adhesives.

[0006] To achieve the objectives of this invention, the slot insulation material for the motor of a low-altitude aircraft of this invention comprises a first insulating paper layer, a film layer, and a second insulating paper layer arranged sequentially from top to bottom; the first insulating paper layer and the second insulating paper layer are each independently selected from aramid fiber paper or polyarylsulfone fiber paper; the film layer is selected from one of polyphenylene sulfide film, polyester film, polynatrimethylene ester film, polyetheretherketone film, or polyetherimide film; wherein, there is no independent adhesive layer between the first insulating paper layer, the film layer, and the second insulating paper layer, and the first insulating paper layer and the second insulating paper layer are directly bonded to the upper and lower surfaces of the film layer by hot pressing, forming a three-layer adhesive-free composite structure of insulating paper-insulating film-insulating paper. Furthermore, in some embodiments of the present invention, both the first insulating paper layer and the second insulating paper layer are aramid paper.

[0007] Furthermore, in some embodiments of the present invention, the thin film layer is a polyphenylene sulfide film, a polynatyl ester film, or a polyether ether ketone film.

[0008] Furthermore, in some embodiments of the present invention, the thickness of the first insulating paper layer and the second insulating paper layer are each independently 0.03 mm to 0.13 mm.

[0009] Furthermore, in some embodiments of the present invention, the thickness of the thin film layer is 0.025 mm to 0.20 mm.

[0010] Furthermore, in some embodiments of the present invention, the total thickness of the three-layer adhesive-free composite structure is 0.08 mm to 0.45 mm.

[0011] Furthermore, in some embodiments of the present invention, the heat resistance rating of the groove insulation material reaches H-class (180°C) or higher.

[0012] Furthermore, in some embodiments of the present invention, the slot insulation material is used for stator slot insulation of motors in electric vertical takeoff and landing (eVTOL) aircraft or unmanned aerial vehicles.

[0013] On the other hand, the present invention also provides a method for preparing the aforementioned slot insulation material for low-altitude aircraft motors, the method comprising the following steps: (1) The first insulating paper layer, the film layer and the second insulating paper layer are passed through the hot press roller from top to bottom to form a three-layer adhesive-free composite structure; (2) After the three-layer glue-free composite structure is formed in step (1), recrystallization heat treatment is performed: the three-layer glue-free composite structure is placed in a heating device, kept at a preset temperature for a preset time, and then cooled to room temperature at a preset rate to allow the polymer chains in the film layer to recrystallize.

[0014] Furthermore, in some embodiments of the present invention, the hot pressing temperature of the hot pressing roller in step (1) is 290~350℃ and the pressure is 6~10 MPa.

[0015] Furthermore, in some embodiments of the present invention, the speed at which the first insulating paper layer, the film layer and the second insulating paper layer pass through the hot press roller in step (1) is 4~6 m / min.

[0016] Furthermore, in some embodiments of the present invention, the preset temperature in step (2) is 180~260℃; preferably, the preset temperature in step (2) is 200~230℃.

[0017] Furthermore, in some embodiments of the present invention, the preset time in step (2) is 30~150 min.

[0018] Furthermore, in some embodiments of the present invention, the cooling to room temperature at a preset rate is a slow cooling to room temperature at a rate of 1°C / min to 5°C / min, in order to control the recrystallized grain size and eliminate internal residual stress.

[0019] This invention does not simply adopt the known concept of "adhesive-free lamination," but rather, based on adhesive-free hot-press lamination, introduces for the first time a recrystallization heat treatment step for the thin film layer, and designs it in conjunction with the hot-pressing process parameters (temperature, pressure, and speed). Specifically: the hot-pressing stage achieves direct adhesive-free bonding between the insulating paper layer and the thin film layer; in the subsequent recrystallization heat treatment stage, by controlling the temperature within a specific range of 120℃ to 260℃, the originally metastable polymer chains in the thin film layer gain sufficient energy to rearrange into the crystal lattice, increasing the crystallinity to over 65%. Simultaneously, during the cooling stage, slow cooling is achieved at a rate of 1℃ / min to 5℃ / min to control the recrystallized grain size and eliminate residual internal stress frozen during the hot-pressing process. This two-step combination of "direct hot-press bonding + recrystallization heat treatment," using only conventional materials (aramid paper, polyphenylene sulfide film, etc.) and conventional equipment, produces unexpected technical effects: (1) Initial tear strength is greatly improved: Comparing Example 1 (hot pressing only, no recrystallization) and Example 1 (hot pressing + recrystallization), it can be seen that under the same material and similar thickness, the initial tear strength in the MD direction is increased from 8N ​​to 32N (an increase of 300%), and the XD direction is increased from 9N to 28N (an increase of 211%), which fundamentally solves the engineering problem of easy-to-break paper in adhesive-free composite groove insulation materials.

[0020] (2) Without sacrificing other key performance: Compared with the adhesive composite solution (Comparative Example 2), the present invention achieves a smaller total thickness (approximately 0.11 mm in Example 1 vs. approximately 0.14~0.15 mm in Comparative Example 2) and a comparable breakdown voltage, while having comparable or even better tear strength, thus meeting the lightweight requirements of low-altitude aircraft.

[0021] (3) The heat resistance rating can reach H level (180℃) or above, and no organic adhesives are required, making the production process more environmentally friendly. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the structure of the slot insulation material for the motor of the low-altitude aircraft of the present invention. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. It should be understood that the following description is merely illustrative and not intended to limit the invention.

[0024] The terms “comprising,” “including,” “having,” “containing,” or any other variations thereof, as used herein, are intended to cover a non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0025] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0026] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically disclosing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether the range is disclosed individually. For example, when the range “1 to 5” is disclosed, the described range should be interpreted as including the ranges “1 to 4”, “1 to 3”, “1 to 2”, “1 to 2 and 4 to 5”, “1 to 3 and 5”, etc. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0027] The singular form includes the plural objects of discussion unless the context clearly indicates otherwise. "Optional" or "any one" means that the matter or event described thereafter may or may not occur, and the description includes both the possibility that the event occurs and the possibility that the event does not occur.

[0028] The indefinite articles “a” and “an” preceding an element or component of this invention do not impose any limitation on the quantity (i.e., number of times) of the element or component. Therefore, “an” or “a” should be interpreted as including one or at least one, and the singular form of an element or component also includes the plural form, unless the quantity clearly refers only to the singular form.

[0029] Furthermore, the terms "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., described below refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms are not necessarily directed at the same embodiment or example. Moreover, the technical features involved in the various embodiments of the present invention can be combined with each other as long as they do not conflict with each other.

[0030] Example 1 A slot insulation material for a low-altitude aircraft motor, the preparation method of which is as follows: a) Pass the first layer of aramid fiber paper roll with a thickness of 0.04 mm, the second layer of aramid fiber paper roll with a thickness of 0.05 mm, and the third layer of aramid fiber paper roll with a thickness of 0.04 mm through the hot press roller in sequence from top to bottom. The hot pressing temperature is 300±5℃, the pressure is 8MPa, and the speed is 5m / min. b) After the above materials are rolled up, place them in an oven, set the temperature to 230℃, and keep them at that temperature for 90 minutes (to ensure that the PPS molecules are fully recrystallized and to improve the material properties). c) Subsequently, the material was slowly cooled to room temperature at a rate of 2℃ / min to obtain a polyphenylene sulfide aramid fiber material with a thickness of 0.113 mm for slot insulation.

[0031] Example 2 A slot insulation material for a low-altitude aircraft motor, the preparation method of which is as follows: a) Pass the first layer of aramid fiber paper roll with a thickness of 0.05mm, the second layer of aramid fiber paper roll with a thickness of 0.05mm, and the third layer of aramid fiber paper roll with a thickness of 0.05mm through the hot press roller in sequence from top to bottom. The hot pressing temperature is 310±5℃, the pressure is 10MPa, and the speed is 4m / min. b) After the above materials are rolled up, place them in an oven, set the temperature to 230℃, and keep them at that temperature for 90 minutes (to ensure that the polyphenylene sulfide molecules are fully recrystallized and to improve the material performance). c) The material was then slowly cooled to room temperature at a rate of 2°C / min to obtain 0.132 mm of polyphenylene sulfide aramid fiber material for slot insulation.

[0032] Example 3 A slot insulation material for a low-altitude aircraft motor, the preparation method of which is as follows: a) Pass the first layer of aramid fiber paper roll with a thickness of 0.04 mm, the second layer of aramid fiber paper roll with a thickness of 0.075 mm, and the third layer of aramid fiber paper roll with a thickness of 0.04 mm through the hot press roller in sequence from top to bottom. The hot pressing temperature is 300±5℃, the pressure is 7MPa, and the speed is 6m / min. b) After the above materials are rolled up, place them in an oven, set the temperature to 200℃, and keep them at that temperature for 120 minutes (to ensure that the polynatate molecules are fully recrystallized and to improve the material properties). c) The material was then slowly cooled to room temperature at a rate of 3°C / min to obtain a 0.141 mm diameter polynatride aramid fiber material for slot insulation.

[0033] Comparative Example 1 The first layer of aramid fiber paper roll with a thickness of 0.04 mm, the second layer of aramid fiber paper roll with a thickness of 0.05 mm, and the third layer of aramid fiber paper roll with a thickness of 0.04 mm are passed through a hot press roller from top to bottom. The hot pressing temperature is 300±5℃, the pressure is 8MPa, and the speed is 5m / min, directly obtaining a 0.117 mm thick polyphenylene sulfide aramid fiber material for groove insulation.

[0034] Comparative Example 2 a) Pass the first layer of aramid fiber paper roll with a thickness of 0.04 mm, the second layer of aramid fiber paper roll with a thickness of 0.05 mm, and the third layer of aramid fiber paper roll with a thickness of 0.04 mm through the hot press roller in sequence from top to bottom. The hot pressing temperature is 300±5℃, the pressure is 8MPa, and the speed is 5m / min.

[0035] b) After the above materials are rolled up, place them in an oven, set the temperature to 120℃, and keep them warm for 90 minutes; c) The material was then slowly cooled to room temperature at a rate of 2°C / min to obtain 0.115 mm of polyphenylene sulfide aramid fiber material for slot insulation.

[0036] Comparative Example 3 a) Pass the first layer of aramid fiber paper roll with a thickness of 0.04 mm, the second layer of aramid fiber paper roll with a thickness of 0.05 mm, and the third layer of aramid fiber paper roll with a thickness of 0.04 mm through the hot press roller in sequence from top to bottom. The hot pressing temperature is 300±5℃, the pressure is 8MPa, and the speed is 5m / min.

[0037] b) After the above materials are rolled up, place them in an oven, set the temperature to 280℃, and keep them warm for 90 minutes; c) The material was then slowly cooled to room temperature at a rate of 2°C / min to obtain 0.087 mm of polyphenylene sulfide aramid fiber material for slot insulation.

[0038] Comparative Example 4 a) Pass the first layer of aramid fiber paper roll with a thickness of 0.04 mm, the second layer of aramid fiber paper roll with a thickness of 0.05 mm, and the third layer of aramid fiber paper roll with a thickness of 0.04 mm through the hot press roller in sequence from top to bottom. The hot pressing temperature is 300±5℃, the pressure is 8MPa, and the speed is 5m / min.

[0039] b) After the above materials are rolled up, place them in an oven, set the temperature to 230℃, and keep them warm for 90 minutes; c) Subsequently, the material was cooled to room temperature at a rate of 10°C / min to obtain 0.108 mm of polyphenylene sulfide aramid fiber material for slot insulation.

[0040] Comparative Example 5 The first layer of aramid fiber paper roll with a thickness of 0.04 mm, the second layer of polyphenylene sulfide film roll with a thickness of 0.05 mm, and the third layer of aramid fiber paper roll with a thickness of 0.04 mm are laminated according to a solvent-based dry lamination scheme to obtain a polyphenylene sulfide aramid fiber material for slot insulation with a thickness of 0.142 mm.

[0041] The test results of the above embodiments and comparative examples are compared as follows:

[0042] From the above Examples 1 and Comparative Examples 1-5, it can be seen that: ① If the adhesive-free composite groove insulation material of the present invention does not undergo a high-temperature crystallization treatment stage, the initial tear strength is significantly lower, and paper tearing is likely to occur in practical applications; ② If the temperature is too high or too low during the high-temperature recrystallization heat preservation stage of the adhesive-free composite groove insulation material of the present invention, the product performance will be significantly affected; ③ If the cooling rate is too fast during the recrystallization cooling stage of the adhesive-free composite groove insulation material of the present invention, the product performance will also be affected; ④ The mechanical and electrical properties of the adhesive-free composite groove insulation material of the present invention are comparable to those of traditional dry composite materials, but the thickness of the adhesive-free composite groove insulation material is significantly thinner, making it more suitable for the lightweight requirements of low-altitude aircraft.

[0043] Those skilled in the art will readily understand that the above description is merely a partial example 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 within the scope of protection of the present invention.

Claims

1. A slot insulation material for a low-altitude aircraft motor, characterized in that, The slot insulation material for the motor of the low-altitude aircraft includes a first insulating paper layer, a film layer, and a second insulating paper layer arranged sequentially from top to bottom; the first insulating paper layer and the second insulating paper layer are each independently selected from aramid fiber paper or polyarylsulfone fiber paper; the film layer is selected from one of polyphenylene sulfide film, polyester film, polynatrimethylene ester film, polyetheretherketone film, or polyetherimide film; wherein, there is no independent adhesive layer between the first insulating paper layer, the film layer, and the second insulating paper layer, and the first insulating paper layer and the second insulating paper layer are directly bonded to the upper and lower surfaces of the film layer by hot pressing, forming a three-layer adhesive-free composite structure of insulating paper-insulating film-insulating paper.

2. The slot insulation material for low-altitude aircraft motors according to claim 1, characterized in that, Both the first insulating paper layer and the second insulating paper layer are aramid paper; preferably, the thickness of the first insulating paper layer and the second insulating paper layer is independently 0.03mm to 0.13mm.

3. The slot insulation material for low-altitude aircraft motors according to claim 1, characterized in that, The film layer is a polyphenylene sulfide film, a polynatyl ester film, or a polyether ether ketone film; preferably, the thickness of the film layer is 0.025 mm to 0.20 mm.

4. The slot insulation material for low-altitude aircraft motors according to claim 1, characterized in that, The total thickness of the three-layer adhesive-free composite structure is 0.08mm to 0.45mm; preferably, the heat resistance rating of the slot insulation material reaches H level or above; preferably, the slot insulation material is used for stator slot insulation of motors in electric vertical take-off and landing aircraft or UAVs.

5. The method for preparing the slot insulation material for the motor of a low-altitude aircraft according to any one of claims 1-4, characterized in that, The method includes the following steps: (1) The first insulating paper layer, the film layer and the second insulating paper layer are passed through the hot press roller from top to bottom to form a three-layer adhesive-free composite structure; (2) After the three-layer glue-free composite structure is formed in step (1), recrystallization heat treatment is performed: the three-layer glue-free composite structure is placed in a heating device, kept at a preset temperature for a preset time, and then cooled to room temperature at a preset rate to allow the polymer chains in the film layer to recrystallize.

6. The method for preparing the slot insulation material for the motor of a low-altitude aircraft according to claim 5, characterized in that, In step (1), the hot pressing temperature of the hot pressing roller is 290~350℃ and the pressure is 6~10 MPa.

7. The method for preparing the slot insulation material for the motor of a low-altitude aircraft according to claim 5, characterized in that, In step (1), the speed at which the first insulating paper layer, the film layer, and the second insulating paper layer pass through the hot press roller is 4~6 m / min.

8. The method for preparing the slot insulation material for the motor of a low-altitude aircraft according to claim 5, characterized in that, The preset temperature in step (2) is 180~260℃; preferably, the preset temperature in step (2) is 200~230℃.

9. The method for preparing the slot insulation material for the motor of a low-altitude aircraft according to claim 5, characterized in that, The preset time in step (2) is 30~150min.

10. The method for preparing the slot insulation material for the motor of a low-altitude aircraft according to claim 5, characterized in that, The cooling to room temperature at the preset rate is a slow cooling to room temperature at a rate of 1°C / min to 5°C / min.

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