BOPEN film for new energy automobile motor and preparation method of BOPEN film

Abstract

The invention relates to the technical field of plastic films, in particular to a BOPEN film for a new energy automobile motor and a preparation method thereof.The preparation method comprises the steps that a PEN raw material dispersed with an anti-adhesion material is placed on the two surface layers (A layer) of the film through the ABA three-layer co-extrusion technology, a PEN raw material containing a nucleating agent is placed on the middle layer (B layer) of the film, and the BOPEN film is prepared. The film is prepared by proportioning, conveying, drying, filtering, melt extrusion, sheet casting and longitudinal and transverse stretching, the anti-adhesion material in the layer A is inorganic micron-scale silicon dioxide, the content of the inorganic micron-scale silicon dioxide in the PEN raw material of the layer A is 0.01-1wt%, the nucleating agent in the layer B is inorganic nano-scale silicon dioxide, the particle size distribution of the inorganic nano-scale silicon dioxide in the PEN raw material of the layer B is 300-1000 nanometers, and the content of the inorganic nano-scale silicon dioxide in the PEN raw material of the layer B is below 0.01-1wt%. According to the invention, the dimensional stability, mechanical properties and other mechanical properties of the PEN film are improved by adopting a mode of longitudinal successive stretching and then transverse stretching, and the crystallinity of the film is increased by adding the nucleating agent, so that the heat resistance and other electrical insulation properties of the PEN film are further improved.

Description

Technical Field

[0001] The present application relates to the field of plastic film technology, and specifically to a BOPEN film for new energy vehicle motors and a preparation method thereof. Background Art

[0002] At present, PEN is made by direct esterification or transesterification of 2,6-naphthalene dicarboxylic acid or 2,6-naphthalene dimethyl ester with ethylene glycol and then polycondensation. Its chemical structure is similar to PET (polyethylene terephthalate), but the naphthalene ring (conjugated benzene ring) in the PEN molecule replaces the single benzene ring in PET. Its planar structure is larger, the molecular chain is more entangled, and the rigidity is stronger. Due to its specific structure, PEN has better heat resistance, electrical insulation, barrier properties, chemical stability and other properties than PET, so it has a wider range of application scenarios than PET materials.

[0003] BOPEN (biaxially oriented polyethylene 2,6-naphthalate) film has significantly improved performance in all aspects compared to BOPET (biaxially oriented polyethylene terephthalate) film due to its particular molecular structure and special process of biaxial stretching. It is widely used in the fields of motors of F class and above for new energy vehicles, tape bases, FPC (flexible printed circuit boards) for new energy vehicles, substrates for optoelectronic materials, 5G communications, etc. In the field of new energy motors, films with better heat resistance and insulation properties are needed. However, at present, there are no industrialized BOPEN film products of this type on the market, and most of them are still in the experimental or pilot stage, which greatly limits the use of new energy motors. Summary of the invention

[0004] In order to improve the problems in the above-mentioned background technology, the present application provides a BOPEN film for new energy vehicle motors and a preparation method thereof.

[0005] The BOPEN film for new energy vehicle motor provided in this application adopts the following technical solution:

[0006] A method for preparing a BOPEN film for a new energy vehicle motor, the specific steps of the preparation method are:

[0007] Step 1: Melt extrusion and sheet casting: PEN raw materials and other auxiliary materials in a certain proportion are mixed and transported, pre-crystallized and dried, melt extruded, melt filtered and then sheet cast;

[0008] Step 2: biaxially oriented film formation: the cast sheet is longitudinally stretched and transversely stretched, and then pulled and rolled up to obtain the biaxially oriented PEN film for the new energy vehicle motor;

[0009] Through the ABA three-layer co-extrusion technology, a PEN raw material dispersed with an anti-adhesive material is placed on two surface layers (A layer) of a film, and a PEN raw material containing a nucleating agent is placed on a middle layer (B layer) of the film, and the film is obtained through proportioning, conveying, drying, filtering, melt extrusion, sheet casting and longitudinal and transverse stretching; the anti-adhesive material in the A layer is inorganic micron-grade silica, with a particle size distribution between 1.0 and 4.5 microns, and its content in the A layer PEN raw material is 0.01%-1wt%; the B layer nucleating agent is inorganic nano-grade silica, with a particle size distribution between 300 and 1000 nanometers, and its content in the B layer PEN raw material is 0.01%-1wt%.

[0010] Preferably, the PEN raw material containing inorganic micron-sized silica is prepared by using a twin-screw extruder to melt-extrude a certain proportion of micron-sized silica and the PEN raw material into slices for the film A layer.

[0011] Preferably, the PEN raw material containing inorganic nano-silica is prepared by using a twin-screw extruder to melt-extrude a certain proportion of nano-silica and the PEN raw material into slices for the film B layer.

[0012] Preferably, before extrusion melting, a solid phase viscosity increasing process is used, wherein the solid phase viscosity increasing is to make the intrinsic viscosity of the PEN raw material with an intrinsic viscosity of 0.6-0.68 dL / g reach 0.75-1.2 dL / g, preferably 0.8-1.0 dL / g after solid phase viscosity increasing.

[0013] Preferably, in step 1 and step 2,

[0014] (1) The A and B layers are melt-extruded using twin-screw extruders respectively. The working conditions are as follows: the dried PEN raw materials are put into respective twin-screw extruders with vacuum exhaust in proportion, the aspect ratio of the extruder screw is 25-40, the screw speed is controlled at 250-600 RPM, and the temperatures of the preheating, shearing, melting, and homogenizing sections are 270±10°C, 285±20°C, 290±20°C, and 285±20°C, respectively;

[0015] (2) The melts of the two layers A and B are separated by a three-layer distributor and merged at the outlet of a three-layer T-die to extrude the mixed melts. The temperature of the three-layer distributor and the three-layer die is 270-320° C.;

[0016] (3) The melt cast from the three-layer T-die is adsorbed by a high-voltage electrostatic wire and attached to the surface of the roller to form a casting sheet. The return water temperature of the roller is set to 20-60°C;

[0017] (4) After the cast sheet is peeled off from the roller, the thickness is measured and the sheet is longitudinally stretched along the length direction. The preheating temperature is 90-120°C. The stretching is performed by far infrared heating at a stretching temperature of 120-160°C. The cooling temperature is controlled at 40-90°C. The longitudinal stretching multiple is 1.5-5 times.

[0018] (5) The transverse stretching is to introduce the film after the longitudinal stretching into the transverse stretching area, wherein the preheating temperature is 100-130°C, the stretching temperature is 130-165°C, and after the heat setting temperature is 200-240°C, it is gradually cooled to room temperature, and the stretching ratio is 2-5.5 times;

[0019] The traction winding adopts contact winding, and the winding tension is controlled between 200-500N, and finally a biaxially oriented PEN film for new energy vehicle motors is obtained.

[0020] The present application also discloses a BOPEN film for new energy vehicle motors, which is prepared by the above-mentioned preparation method.

[0021] In summary, the present application includes at least one of the following beneficial technical effects: the BOPEN film is prepared by the present application, which adopts the method of longitudinal stretching and then transverse stretching to improve the dimensional stability, mechanical properties and other mechanical properties of the PEN film, and by adding a nucleating agent to increase the crystallinity of the film to further improve the heat resistance and other electrical insulation properties of the PEN film. Therefore, the BOPEN of the present application can be suitable for the needs of new energy motors. DETAILED DESCRIPTION

[0022] The present application is described in further detail below.

[0023] The present application discloses a method for preparing a BOPEN film for a new energy vehicle motor, the preparation method comprising:

[0024] Step 1:

[0025] Melt extrusion: firstly, the PEN raw material and other auxiliary materials in a certain proportion are mixed and transported, and after pre-crystallization and drying, the raw material dispersed with anti-adhesion material is placed on the two surface layers (A layer) of the film and the raw material containing nucleating agent is placed on the middle layer (B layer) of the film, and they are extruded through a twin-screw extruder respectively. The melts of the A and B layers are separated by a three-layer distributor and merged at the outlet of the three-layer T-die to extrude the mixed melt. The temperature of the three-layer distributor and the three-layer die is 270-320°C; Casting sheet: The melt of the mixed solution cast from the three-layer T-die is attached to the surface of the roller after being adsorbed by a high-voltage electrostatic wire to form a casting sheet, and the return water temperature of the roller is set to 20-60°C;

[0026] Step 2:

[0027] Biaxially oriented film: The cast sheet is stretched longitudinally and transversely, then pulled and rolled to obtain BOPEN film; the preheating temperature for longitudinal stretching is 90-120℃, far infrared heating is used for longitudinal stretching, the stretching temperature is 120-160℃, the cooling temperature is controlled at 40-90℃, and the longitudinal stretching multiple is 1.5-5 times;

[0028] Transverse stretching is to introduce the film after longitudinal stretching into the transverse stretching area, wherein the transverse stretching preheating temperature is 100-130°C, the transverse stretching temperature is 130-165°C, and after the heat setting temperature is 200-240°C, it is gradually cooled to room temperature, and the transverse stretching multiple is 2-5.5 times;

[0029] The traction winding adopts contact winding, and the winding tension is controlled between 200-500N, and finally the BOPEN film is produced.

[0030] In step one, the anti-adhesion raw material in layer A is inorganic micron-grade silica with a particle size distribution of 1.0-4.5 microns and a content of 0.01%-1wt% in layer A; the nucleating agent in layer B is inorganic nano-grade silica with a particle size distribution of 300-1000 nanometers and a content of 0.01%-1wt% in layer B; the aspect ratio of the screw of the twin-screw extruder is 25-40, the screw speed is controlled at 250-600RPM, and the temperatures of the preheating, shearing, melting and homogenizing sections are 270±10°C, 285±20°C, 290±20°C and 285±20°C, respectively.

[0031] Before melt extrusion, a solid phase viscosity increasing process is used. The solid phase viscosity increasing is to make the intrinsic viscosity of the PEN raw material with an intrinsic viscosity of 0.6-0.68 dL / g reach 0.75-1.2 dL / g, preferably 0.8-1.0 dL / g after solid phase viscosity increasing.

[0032] The present application also includes a BOPEN film for new energy vehicle motors, which is prepared by the above-mentioned preparation method.

[0033] Example 1

[0034] In this embodiment, the production method is operated using the above steps, and the specific raw material ratio and equipment parameters use the following data to produce the BOPEN film.

[0035] (1) Raw material ratio: the surface layer (A layer) ratio is 0.01wt% micron silicon dioxide (particle size distribution is 1.0 micron) + 99.99wt% PEN raw material (intrinsic viscosity is 0.60dL / g); the middle layer (B layer) ratio is 0.01wt% micron silicon dioxide (particle size distribution is 300 nanometers) + 99.99wt% PEN raw material (intrinsic viscosity is 0.60dL / g);

[0036] (2) A twin-screw extruder with a length-to-diameter ratio of 35 and vacuum exhaust was used, the screw speed was controlled at 400 RPM, and the temperatures of the preheating, shearing, melting, and homogenizing sections were 270°C, 285°C, 290°C, and 285°C, respectively;

[0037] (3) The temperature of the three-layer distributor and the three-layer die is 270°C;

[0038] (4) The roller temperature is set to 25°C;

[0039] (5) The preheating temperature for longitudinal stretching is 90°C, the stretching uses far-infrared heating, the stretching temperature is 120°C, the cooling temperature is 40°C, and the longitudinal stretching multiple is 2 times;

[0040] (6) The preheating temperature for transverse stretching is 100°C, the stretching temperature is 130°C, the heat setting temperature is 200°C, and the stretching ratio is 2 times;

[0041] (7) The winding tension is set to 200N.

[0042] Example 2

[0043] In this embodiment, the production method is the same as that in Embodiment 1, and the specific raw material ratio and equipment parameters adopt the following data to produce the BOPEN film.

[0044] (1) Raw material ratio: the ratio of the surface layer (A layer) is 0.05wt% micron silicon dioxide (particle size distribution is 1.0 micron) + 99.95wt% PEN raw material (intrinsic viscosity is 0.63dL / g); the ratio of the middle layer (B layer) is 0.05wt% micron silicon dioxide (particle size distribution is 300 nanometers) + 99.95wt% PEN raw material (intrinsic viscosity is 0.63dL / g);

[0045] (2) A twin-screw extruder with a length-to-diameter ratio of 35 and vacuum exhaust was used, the screw speed was controlled at 400 RPM, and the temperatures of the preheating, shearing, melting, and homogenizing sections were 275°C, 290°C, 290°C, and 285°C, respectively;

[0046] (3) The temperature of the three-layer distributor and the three-layer die is 275°C;

[0047] (4) The roller temperature is set to 35°C;

[0048] (5) The preheating temperature for longitudinal stretching is 90°C, the stretching uses far-infrared heating, the stretching temperature is 120°C, the cooling temperature is 40°C, and the longitudinal stretching multiple is 3.0 times;

[0049] (6) The transverse stretching preheating temperature is 100°C, the stretching temperature is 130°C, the heat setting temperature is 200°C, and the stretching ratio is 3.0 times;

[0050] (7) The winding tension is set to 200N.

[0051] Example 3

[0052] In this embodiment, the production method is the same as that in Embodiment 1, and the specific raw material ratio and equipment parameters adopt the following data to produce the BOPEN film.

[0053] (1) Raw material ratio: the surface layer (A layer) ratio is 0.05wt% micron silicon dioxide (particle size distribution is 1.0 micron) + 99.95wt% PEN raw material (intrinsic viscosity is 0.7dL / g), and the middle layer (B layer) ratio is 0.05wt% micron silicon dioxide (particle size distribution is 300 nanometers) + 99.95wt% PEN raw material (intrinsic viscosity is 0.7dL / g);

[0054] (2) A twin-screw extruder with a length-to-diameter ratio of 35 and vacuum exhaust was used, the screw speed was controlled at 400 RPM, and the temperatures of the preheating, shearing, melting, and homogenizing sections were 280°C, 295°C, 295°C, and 285°C, respectively;

[0055] (3) The temperature of the three-layer distributor and the three-layer die is 280°C;

[0056] (4) The roller temperature is set to 45°C;

[0057] (5) The preheating temperature for longitudinal stretching is 95°C, the stretching uses far-infrared heating, the stretching temperature is 125°C, the cooling temperature is 45°C, and the longitudinal stretching multiple is 3.0 times;

[0058] (6) Transverse stretching preheating temperature is 105°C, stretching temperature is 135°C, heat setting temperature is 210°C, and stretching ratio is 3.0 times;

[0059] (7) The winding tension is set to 300N.

[0060] Example 4

[0061] In this embodiment, the production method is the same as that in Embodiment 1, and the specific raw material ratio and equipment parameters adopt the following data to produce the BOPEN film.

[0062] (1) Raw material ratio: the surface layer (A layer) ratio is 0.1wt% micron silicon dioxide (particle size distribution is 2.0 microns) + 99.9wt% PEN raw material (intrinsic viscosity is 0.7dL / g); the middle layer (B layer) ratio is 0.05wt% micron silicon dioxide (particle size distribution is 500 nanometers) + 99.95wt% PEN raw material (intrinsic viscosity is 0.7dL / g);

[0063] (2) A twin-screw extruder with a length-to-diameter ratio of 35 and vacuum exhaust was used, the screw speed was controlled at 400 RPM, and the temperatures of the preheating, shearing, melting, and homogenizing sections were 280°C, 295°C, 295°C, and 285°C, respectively;

[0064] (3) The temperature of the three-layer distributor and the three-layer die is 285°C;

[0065] (4) The roller temperature is set to 55°C;

[0066] (5) The preheating temperature for longitudinal stretching is 100°C, far infrared heating is used for stretching, the stretching temperature is 130°C, the cooling temperature is 45°C, and the longitudinal stretching multiple is 3.5 times;

[0067] (6) The preheating temperature for transverse stretching is 110°C, the stretching temperature is 135°C, the heat setting temperature is 220°C, and the stretching ratio is 3.2 times;

[0068] (7) The winding tension is set to 350N.

[0069] Example 5

[0070] In this embodiment, the production method is the same as that in Embodiment 1, and the specific raw material ratio and equipment parameters adopt the following data to produce the BOPEN film.

[0071] Raw material ratio: The ratio of the surface layer (A layer) is 0.2wt% micron silicon dioxide (particle size distribution is 2.0 microns) + 99.8wt% PEN raw material (intrinsic viscosity is 0.7dL / g). The ratio of the middle layer (B layer) is 0.1wt% micron silicon dioxide (particle size distribution is 500 nanometers) + 99.9wt% PEN raw material (intrinsic viscosity is 0.7dL / g);

[0072] Other parameters are the same as in Example 4.

[0073] Example 6

[0074] In this embodiment, the production method is the same as that in Embodiment 1, and the specific raw material ratio and equipment parameters adopt the following data to produce the BOPEN film.

[0075] (1) Raw material ratio: the surface layer (A layer) ratio is 1wt% micron silicon dioxide (particle size distribution is 2.0 microns) + 99wt% PEN raw material (intrinsic viscosity is 0.85 dL / g); the middle layer (B layer) ratio is 1wt% micron silicon dioxide (particle size distribution is 700 nanometers) + 99wt% PEN raw material (intrinsic viscosity is 0.85 dL / g);

[0076] (2) The preheating temperature for longitudinal stretching is 100°C, the stretching uses far-infrared heating, the stretching temperature is 130°C, the cooling temperature is 45°C, and the longitudinal stretching multiple is 3.8 times;

[0077] (3) The transverse stretching preheating temperature is 110°C, the stretching temperature is 140°C, the heat setting temperature is 230°C, and the stretching ratio is 3.7 times;

[0078] Other parameters are the same as in Example 5.

[0079] Comparative Example 1,

[0080] The only difference between this comparative example and Example 6 is that the PEN raw material with an intrinsic viscosity of 0.8 dL / g is used, and the other parts remain unchanged. The production method is the same as that of Example 1.

[0081] Comparative Example 2: The only difference between this comparative example and Example 6 is that the longitudinal stretching multiple is 3 times, and the other aspects remain unchanged. The production method is the same as that of Example 1.

[0082] Comparative Example 3: The only difference between this comparative example and Example 6 is that the transverse stretching ratio is 3 times, and the other aspects remain unchanged. The production method is the same as that of Example 1.

[0083] Comparative Example 4: The only difference between this comparative example and Example 6 is that the heat setting temperature is 220°C, and the other conditions remain unchanged. The production method is the same as that of Example 1.

[0084] The above-mentioned Examples 1-6 and Comparative Examples 1-4 were subjected to the following relevant performance tests respectively: 1. Mechanical performance test: refer to the test method specified in the test method GB / T13542.4-2009;

[0085] 2. Oligomer precipitation test: The test method is to take the BOPEN film obtained in each embodiment of the present invention and accurately weigh T0g (retain 4 decimal places), extract it in boiling xylene for 24 hours, take out the film, wash it, dry it in a 100-degree circulating drying oven, and weigh T1g (retain 4 decimal places), and obtain the extraction value = (T1 / T0)*100%;

[0086] 3. Long-term heat resistance evaluation: refer to the GB11026 series standard "Long-term heat resistance index of electrical insulation materials" test, and test under electrical and mechanical conditions respectively;

[0087] 4. Insulation evaluation: Refer to the test method specified in GB / T13542.4-2009. Specific test data are shown in Table 1 and Table 2.

[0088] Table 1:

[0089]

[0090]

[0091] Table 2:

[0092]

[0093] It can be seen from Table 1 and Table 2 that the BOPEN film prepared in the present application has good insulating properties and insulation properties; the crystallinity of the film is increased by adding a nucleating agent to further improve the heat resistance of the PEN film.

[0094] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a BOPEN film for a new energy vehicle motor, characterized in that: The specific steps of the preparation method are: Step 1: Melt extrusion and sheet casting: PEN raw materials and other auxiliary materials in a certain proportion are mixed and transported, pre-crystallized and dried, melt extruded, melt filtered and then sheet cast; Step 2: biaxially oriented film formation: the cast sheet is longitudinally stretched and transversely stretched, and then pulled and rolled up to obtain the biaxially oriented PEN film for the new energy vehicle motor; The raw material containing anti-adhesion material is placed on the two surface layers (A layer) of the film through ABA three-layer co-extrusion technology, and the raw material containing nucleating agent is placed in the middle layer (B layer) of the film. The film is obtained through proportioning, conveying, drying, filtering, melt extrusion, casting and longitudinal and transverse stretching; the anti-adhesion raw material in the A layer is inorganic micron-grade silica, with a particle size distribution of 1.0-4.5 microns, and the content in the A layer is 0.01%-1wt%; the nucleating agent in the B layer is inorganic nano-grade silica, with a particle size distribution of 300-1000 nanometers, and the content in the B layer is 0.01%-1wt%.

2. The method for preparing a BOPEN film for a new energy vehicle motor according to claim 1, characterized in that: The raw material containing inorganic micron-sized silica is extruded through a twin-screw extruder to melt-extrude a certain proportion of micron-sized silica and PEN raw material into slices for use in the A layer of the film.

3. The method for preparing a BOPEN film for a new energy vehicle motor according to claim 1, characterized in that: The raw material containing inorganic nano-silicon dioxide is melt-extruded and sliced ​​with a certain proportion of nano-silicon dioxide and PEN raw material through a twin-screw extruder for use in the film B layer.

4. The method for preparing a BOPEN film for a new energy vehicle motor according to claim 1, characterized in that: Before extrusion melting, a solid phase viscosity increasing process is used, wherein the intrinsic viscosity of the PEN raw material with an intrinsic viscosity of 0.6-0.68 dL / g is increased to 0.75-1.2 dL / g, preferably 0.8-1.0 dL / g, after solid phase viscosity increasing.

5. The method for preparing a BOPEN film for a new energy vehicle motor according to claim 1, characterized in that: The A and B layers are melt extruded by twin-screw extruders respectively. The working conditions are as follows: the dried PEN raw materials are put into respective twin-screw extruders with vacuum exhaust in proportion. The aspect ratio of the extruder screw is 25-40. The screw speed is controlled at 250-600RPM. The temperatures of the preheating, shearing, melting and homogenizing sections are 270±10℃, 285±20℃, 290±20℃ and 285±20℃ respectively. The melts of A and B are separated by a three-layer distributor and then merged at the outlet of a three-layer T-die to extrude the mixed melt. The temperature of the three-layer distributor and the three-layer die is 270-320°C. The melt cast from the three-layer T-die is adsorbed by high-voltage electrostatic wire and adheres to the surface of the roller to form a casting sheet. The return water temperature of the roller is set at 20-60℃. After the casting sheet is peeled off from the roller, the thickness is measured and the sheet is longitudinally stretched along the length direction. The preheating temperature is 90-120°C. The stretching uses far-infrared heating at a stretching temperature of 120-160°C. The cooling temperature is controlled at 40-90°C. The longitudinal stretching multiple is 1.5-5 times. The transverse stretching is to introduce the film after longitudinal stretching into the transverse stretching area, wherein the preheating temperature is 100-130°C, the stretching temperature is 130-165°C, and after the heat setting temperature is 200-240°C, it is gradually cooled to room temperature, and the stretching ratio is 2-5.5 times; The traction winding adopts contact winding, and the winding tension is controlled between 200-500N.

6. A BOPEN film for new energy vehicle motors, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 5.

Images