A molding apparatus and molding method for polyimide engineering parts

Abstract

A molding apparatus and method for polyimide engineering parts are disclosed, relating to the technical field of molding methods for engineering plastics. The apparatus includes: a liquid tank for holding raw material resin liquid; a molding platform capable of moving up and down within the liquid tank; a laser line scanner for scanning the liquid film above the molding platform to obtain a support layer; and a laser spot emitter for irradiating a predetermined position of the support layer to complete the curing of the polyimide. This invention uses a two-step molding method, avoiding the use of powdered raw materials, and instead molding in a liquid environment. The support layer material of the initial structure is only laser scanned and not completely cured, allowing for dissolution and recycling with reagents, reducing material waste and significantly improving utilization efficiency. Furthermore, it is unaffected by objective factors such as mold and sample size, enabling the processing of large-size, complex-shaped parts with high precision.

Description

Technical Field

[0001] This invention relates to the field of molding methods for engineering plastics, and more particularly to a molding apparatus and molding method for polyimide engineering parts. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Polyimide (PI) is an excellent specialty engineering plastic with superior comprehensive properties. It can withstand temperatures exceeding 400℃, and its long-term operating temperature can reach 300℃. However, this improved heat resistance also means reduced processing performance. The processing temperature of polyimide plastics typically exceeds 300℃, making it incompatible with processing equipment used for general engineering plastics, which greatly complicates its molding process.

[0004] PI engineering plastics are typically produced by removing reagents from a partially imidized polyimide solution and drying it to obtain a powder. This powder is then used as raw material for compression molding or extrusion molding, as illustrated by patents CN103232706B, JP2013163800A, and US06538097B2. (A few types with good melt flow properties, such as polyamide-imide and polyether-imide, can be injection molded.) The mainstream compression molding or extrusion molding method involves first preparing the material into rod or sheet profiles, and then machining these profiles to obtain the desired parts. This molding process is limited by factors such as mold size, the thermal conductivity of the material itself, and the generation of small molecules during curing. PI engineering plastics are not suitable for processing thicker parts; the thickness of extruded sheets generally does not exceed 10cm. Furthermore, the material utilization rate is low during the processing of rod and sheet profiles, resulting in significant waste and increasing manufacturing costs.

[0005] Much research on improving molding methods for polyimide (PI) engineering plastics focuses on modifying the material's structure, such as introducing flexible segments, end-capping, and designing special monomer structures. However, the introduction of special structures into the main chain inevitably affects other properties of the material itself.

[0006] Patents CN108774321A and CN106432757A provide a method for preparing complex shapes using polyimide powder, but since the polyimide is sintered in powder form, it is still necessary to prepare the polyimide into powder beforehand, and the manufacturing and molding process cannot avoid the waste of raw materials. Summary of the Invention

[0007] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a molding device and molding method for polyimide engineering parts, which directly processes polyamic acid solution to obtain polyimide parts. The size of the parts is not limited by molds, and the parts are not processed in powder form, thus avoiding waste.

[0008] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0009] The first aspect of the present invention provides a molding apparatus for polyimide engineering parts, comprising:

[0010] Liquid tank, used to hold raw material resin liquid;

[0011] The molding platform can move up and down within the liquid tank;

[0012] A laser line scanner is used to perform line scanning on the liquid film above the molding platform to obtain the support layer;

[0013] A laser spot emitter is used to irradiate the designated positions of the support layer to complete the curing of polyimide.

[0014] A second aspect of the present invention provides a method for molding polyimide engineering parts, comprising the following steps:

[0015] S1. Slice and model the target shape to obtain the thickness and curing position of each layer;

[0016] S2. The molding platform is immersed in a liquid tank containing a raw material resin liquid including polyamic acid and reagents, and a liquid film of a set thickness is formed on the surface of the platform.

[0017] S3. Use a laser line scanner to scan the liquid film and increase the temperature of the liquid film to remove some of the reagents in the liquid film and form a support layer with a set thickness.

[0018] S4. Use a laser spot emitter to irradiate the set curing positions in the support layer to complete the curing of the single-layer polyimide material;

[0019] S5. Repeat steps S2 to S4 to complete the molding of the polyimide engineering part;

[0020] S6. Ultrasonic treatment to remove the support layer material that has not been cured by the laser spot emitter, and obtain the final part;

[0021] In S2, the raw material resin liquid includes a light absorber and / or a photoinitiator, wherein the light absorber is used to raise the temperature under laser scanning or irradiation.

[0022] The beneficial effects of this invention are as follows:

[0023] 1. This invention uses a two-step molding process, which does not use raw materials in powder form, but instead forms the material in a liquid environment. The support layer material of the initial structure is only scanned by laser and is not completely cured. It can be dissolved and recycled by reagents, reducing material waste and greatly improving utilization efficiency. The support layer material completes the final imidization and curing under the irradiation of a point laser. It is not affected by objective factors such as mold and sample size, and can be used to process large-sized and complex-shaped parts with high processing accuracy.

[0024] 2. Based on existing laser forming equipment and combined with the principle of thin film forming, this invention improves the formability of polyimide without changing the basic properties of the original polyimide material, and the resulting material has more stable chemical and physical properties. Attached Figure Description

[0025] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0026] The diagram exaggerates the spacing or dimensions between parts to show their positions; the diagram is for illustrative purposes only.

[0027] Figure 1 This is a schematic diagram of the molding device for polyimide engineering parts in a specific embodiment.

[0028] The components include: 1. Reagent recovery system; 2. Tank cover; 3. Liquid tank; 4. Support layer; 5. Polyimide engineering component; 6. Raw material resin liquid; 7. Laser transmission device; 8. Laser spot emitter; 9. Laser line scanner; 10. Molding platform support; 11. Tank cover support; 12. Laser; and 13. Molding platform. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0030] like Figure 1 As shown, a molding apparatus for polyimide engineering parts includes:

[0031] Liquid tank 3 is used to hold raw material resin liquid 6;

[0032] The molding platform 13 is capable of moving up and down within the liquid tank 3;

[0033] Laser line scanner 9 is used to perform line scanning on the liquid film above the molding platform 13 to obtain a support layer 4 that is partially imidized but not cross-linked and cured.

[0034] The laser spot emitter 8 is used to irradiate the set position of the support layer 4 to complete the curing of polyimide.

[0035] With this setup, the polyimide material is formed in a liquid environment. The material of the support layer 4, which achieves the initial structure through laser scanning, does not undergo complete curing and can be dissolved and recycled using reagents. The material of the support layer 4 completes the final imidization and curing under the irradiation of the dot laser 12. It is not affected by objective factors such as mold and sample size, and can be used to process large-sized and complex-shaped parts with high processing precision.

[0036] Optionally, a transparent cover 2 is provided on the liquid tank 3. The cover 2 is used to close the opening of the liquid tank 3 to maintain a negative pressure environment in the liquid tank 3. The transparent cover 2 allows the laser 12 to pass through, and the molding and curing process of polyimide is completed in the negative pressure environment in the liquid tank 3. The cover 2 is connected to the reagent recovery system 1, which is used to create a negative pressure environment in the space above the liquid surface in the liquid tank 3 and to recover the reagents that are vaporized during the molding and curing process of polyimide.

[0037] Optionally, a cover bracket 11 is connected to the cover 2. The cover bracket 11 can drive the cover 2 to move up and down and back and forth to realize the mechanical locking and opening of the cover 2, and can adjust the opening position of the reagent recovery system 1 on the cover 2 so that it is close to the reagent vaporization position irradiated by the laser 12.

[0038] Optionally, the reagent recovery system 1 includes a vacuum pump, a cooling device, and a storage tank. The vaporized reagent is drawn out of the liquid tank 3 by the vacuum pump and cooled in the cooling device, and finally stored in the storage tank to complete the recovery.

[0039] Optionally, the molding platform 13 is connected to the molding platform support 10. The molding platform support 10 is used for the molding platform 13 to move up and down in the liquid tank 3. It can stop at a set position below the liquid surface to form a liquid film of a set thickness on the upper surface of the molding platform 13. After each layer of material is cured, it moves down a set distance to form a liquid film of a set thickness on the upper surface of the new molding material.

[0040] Optionally, a weighing system is provided on the molding platform support 10, which can measure the weight change of the molding platform 13. When the laser line scanner 9 scans the liquid film on the molding platform 13, the reagent in the raw material resin liquid 6 between the molding platform 13 and the liquid surface evaporates. The surrounding raw material resin liquid 6 cannot be replenished to the support layer 4 due to its high viscosity, which makes the weight measured by the weighing system lower, thereby determining the amount of reagent remaining in the liquid film.

[0041] Optionally, the molding platform support 10 passes through the groove cover 2, and the area through which it passes is airtight.

[0042] Optionally, the laser line scanner 9 and the laser dot emitter 8 are respectively connected to the laser generating device through the laser transmission device 7. The laser emitting device can provide light sources of different wavelengths for different forming stages of materials.

[0043] Optionally, the laser spot emitter 8 can process at multiple points simultaneously.

[0044] Optionally, the molding apparatus for the polyimide engineering part further includes a data processing system and a positioning system; the data system is used to slice and model the target shape, and the positioning system is used to control the movement position of each component.

[0045] The molding method using the above-described polyimide engineering part molding apparatus includes the following steps:

[0046] S1. Slice and model the target shape to obtain the thickness and curing position of each layer;

[0047] S2. The molding platform 13 is immersed in a liquid tank 3 containing a raw material resin liquid 6 including polyamic acid and reagents, and a liquid film of a set thickness is formed on the surface of the molding platform.

[0048] S3. Use a laser line scanner 9 to scan the liquid film and increase the temperature of the liquid film to remove some of the reagents in the liquid film and form a support layer 4 with a set thickness.

[0049] S4. Use laser spot emitter 8 to irradiate the curing positions set in the support layer 4 to complete the curing of the single-layer polyimide material;

[0050] S5. Repeat steps S2 to S4 to complete the molding of polyimide engineering part 5;

[0051] S6. Ultrasonic treatment to remove the support layer 4 material that was not cured by the laser spot emitter 8, and obtain the final part;

[0052] In S2, the raw material resin liquid 6 includes a light absorber and / or a photoinitiator, wherein the light absorber is used to raise the temperature under laser scanning or irradiation.

[0053] Optionally, the light absorber includes one or more of metal oxides, hydroxides, sulfides, and phosphates, and the metal includes one or more of copper, aluminum, iron, nickel, and chromium.

[0054] Optionally, light absorbers may also include inorganic fillers of non-metallic composition.

[0055] Optionally, light absorbers include organic fillers.

[0056] Optionally, the particle size of the light absorber is 0.1–30 μm.

[0057] Optionally, the amount of light absorber added is 1 to 30 wt% of the raw resin solution.

[0058] Optionally, the viscosity range of the raw material resin liquid is 1000-10000 cp·s.

[0059] Optionally, the reagents include one or more of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, xylene, and dioxane.

[0060] Optionally, the raw resin solution includes photosensitive polyimide and a photoinitiator.

[0061] Optionally, in S3, under the scanning of the laser line scanner 9, the raw material resin liquid 6 of the liquid film undergoes partial imidization but not cross-linking and curing to form a support layer 4 with a certain strength; preferably, through process adjustment, the process parameters of the laser line scanner 9 are set such that after scanning, the content of the remaining solvent in the support layer 4 is 0.1 to 5 wt%, which can remain in the static raw material resin liquid 6 without dissolving.

[0062] Optionally, in S4, under the irradiation of the laser spot emitter 8, the material of the support layer 4 completes the imidization and curing process, transforming into a polyimide material.

[0063] Optionally, in S5, the upper surface of the uppermost support layer 4 is used as the molding platform surface in S2, and the position of the molding platform 13 is adjusted to form a liquid film of a set thickness on the upper surface of the uppermost support layer 4.

[0064] Optionally, in S6, the material of the support layer 4 that has not completed the imidization and curing process is subjected to ultrasonic treatment in the reagent, so that the material is detached from the surface of the final part.

[0065] Example 1

[0066] The preparation method of the raw material resin liquid includes: using 4,4-diaminodiphenyl ether and trimellitic anhydride as raw materials, and using acetic anhydride as a dehydrating agent, chemical imidization is carried out; a 30wt% polyamic acid solution is prepared, 3% light absorber is added, and the resin viscosity is controlled at 2000±200cp·s (25℃).

[0067] Among them, nickel-zinc ferrite is selected as the light absorber, and N-methylpyrrolidone is selected as the reagent.

[0068] The preparation method includes the following steps:

[0069] The target shape is sliced ​​and modeled using a data processing system to obtain a layer thickness of 0.8 mm and a set curing position;

[0070] The raw resin liquid is transferred into the liquid tank, the support platform is submerged below the liquid surface of the raw resin liquid, and then rises to a position where the upper surface of the support platform is 0.8 mm below the liquid surface, forming a stable liquid film on the upper surface of the support platform.

[0071] The reagent recovery system is activated, and a laser line scanner is used to scan the liquid film. The light absorber in the liquid film heats up rapidly under the irradiation of the laser, causing the reagent to evaporate and the liquid film to transform into a support layer material.

[0072] When the gravimetric system on the molding platform support detects that the reagent in the liquid film has evaporated to 1 wt%, the scanning stops and the support platform is moved above the surrounding liquid surface.

[0073] A single layer of polyimide is formed by processing different points of the support layer using a laser spot emitter.

[0074] Repeat the above steps until the part is complete;

[0075] The obtained part with the support layer is placed in a reagent for ultrasonic cleaning to fully dissolve the support layer material in the reagent and obtain the final part.

[0076] Example 2

[0077] The difference from Example 1 is that the laser dot emitter is a rectangular dot matrix emitter composed of multiple emitter tubes, which can process multiple points at the same time and quickly complete the molding of a single layer of polyimide.

[0078] Example 3

[0079] The difference from Example 1 is that the preparation method of the raw material resin liquid includes: using diphenylmethane diisocyanate and trimellitic anhydride as raw materials, carrying out a thermal imidization reaction, preparing a 30% wt concentration polyamic acid solution, adding 5% light absorber, and controlling the resin viscosity at 1500±200 cp·s (25℃).

[0080] Graphite was chosen as the light absorber, and N-methylpyrrolidone was chosen as the reagent.

[0081] The laser spot emitter consists of multiple emitters, each with an adjustable direction, which allows multiple beams to be focused onto the point to be processed, thus completing the imidization and curing of the material.

[0082] Example 4

[0083] The difference between this embodiment and Example 1 is that: 4,4-diaminodiphenyl ether and pyromellitic anhydride are used as raw materials, glycidyl methacrylate is introduced as a photosensitive group, diacylphosphine is used as a photoinitiator and hydroxyethyl acrylate is used as an active diluent to prepare a photocurable resin, and the resin viscosity is controlled at 2000±200cp·s (25℃).

[0084] The laser line scanner uses an infrared light source to heat the liquid film to remove reagents until the reagent content in the liquid film is 3 wt%, thus forming a support layer.

[0085] The laser spot emitter uses an ultraviolet light source to photocur and mold the support layer material.

[0086] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A molding method for polyimide engineering parts, characterized in that, include: Liquid tank, used to hold raw material resin liquid; The molding platform can move up and down within the liquid tank; A laser line scanner is used to perform line scanning on the liquid film above the molding platform to obtain the support layer; A laser spot emitter is used to irradiate a predetermined position on the support layer to complete the curing of polyimide; The method steps for manufacturing the polyimide engineering component: S1. Slice and model the target shape to obtain the thickness and curing position of each layer; S2. The molding platform is immersed in a liquid tank containing a raw material resin liquid including polyamic acid and reagents, and a liquid film of a set thickness is formed on the surface of the molding platform. S3. Use a laser line scanner to scan the liquid film and increase the temperature of the liquid film to remove some of the reagents in the liquid film and form a support layer with a set thickness. S4. Use a laser spot emitter to irradiate the set curing positions in the support layer to complete the curing of the single-layer polyimide material; S5. Repeat steps S2 to S4 to complete the molding of the polyimide engineering part; S6. Ultrasonic treatment to remove the support layer material that has not been irradiated and cured by the laser spot emitter (8) to obtain the final part; In S2, the raw material resin includes a light absorber and / or a photoinitiator, wherein the light absorber is used to raise the temperature under laser scanning or irradiation.

2. The molding method for polyimide engineering parts according to claim 1, characterized in that, The liquid tank is equipped with a transparent tank cover, which is used to seal the opening of the liquid tank in order to maintain a negative pressure environment in the liquid tank; The transparent tank cover allows the laser to pass through, completing the molding and curing process of polyimide in a negative pressure environment within the liquid tank; The tank cover is connected to a reagent recovery system, which is used to create a negative pressure environment in the space above the liquid surface in the tank and to recover the reagents that are vaporized during the molding and curing process of polyimide.

3. The molding method for polyimide engineering parts according to claim 2, characterized in that, The tank cover is connected to a tank cover bracket, which can move the tank cover up and down and back and forth; and can adjust the opening position of the reagent recovery system on the tank cover.

4. The molding method for polyimide engineering parts according to claim 2, characterized in that, The reagent recovery system (1) includes a vacuum device, a cooling device and a storage tank.

5. The molding method for polyimide engineering parts according to claim 1, characterized in that, The molding platform is connected to the molding platform support, which is used for the molding platform to move up and down in the liquid tank, and to move down a set distance after each layer of material has cured.

6. The molding method for polyimide engineering parts according to claim 1, characterized in that, The laser line scanner and the laser point emitter are respectively connected to the laser generating device through a laser transmission device, and the laser emitting device can provide light sources of different wavelengths.

7. The molding method for polyimide engineering parts according to claim 6, characterized in that, The laser spot emitter includes multiple emission tubes, which can process at multiple points simultaneously.

8. The molding method for polyimide engineering parts according to claim 1, characterized in that, It includes a data processing system and a positioning system; the data processing system is used to slice and model the target shape, and the positioning system is used to control the movement and position of each component.

9. The molding method for polyimide engineering parts as described in claim 1, characterized in that, In S2, the light absorber includes one or more of metal oxides, hydroxides, sulfides, and phosphates, and the metal includes one or more of copper, aluminum, iron, nickel, and chromium.

10. The molding method for polyimide engineering parts as described in claim 1, characterized in that, In S2, the light absorber includes inorganic fillers with non-metallic components.

11. The molding method for polyimide engineering parts as described in claim 1, characterized in that, In S2, the light absorber includes organic fillers.

12. The molding method for polyimide engineering parts as described in claim 1, characterized in that, In S2, the particle size of the light absorber is 0.1~30μm.

13. The molding method for polyimide engineering parts as described in claim 1, characterized in that, In S2, the amount of light absorber added is 1~30wt% of the raw resin liquid.

14. The molding method for polyimide engineering parts as described in claim 1, characterized in that, In S2, the viscosity range of the raw material resin liquid is 1000-10000 cp•s.

15. The molding method for polyimide engineering parts as described in claim 1, characterized in that, In S2, the raw material resin liquid includes photosensitive polyimide and photoinitiator.

16. The molding method for polyimide engineering parts as described in claim 1, characterized in that, In S2, the reagents include one or more of N-methylpyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, tetrahydrofuran, xylene, and dioxane.

17. The molding method for polyimide engineering parts as described in claim 1, characterized in that, In S3, under the scanning of the laser line scanner, the raw material resin liquid (6) undergoes partial imidization but not cross-linking and curing to form a support layer with a certain strength. Through process adjustment, the process parameters of the laser line scanner (9) are set to: after scanning, the content of the remaining solvent in the support layer is 0.1~5wt%, which can remain in the static raw material resin liquid without dissolving.

18. The molding method for polyimide engineering parts as described in claim 1, characterized in that, In S4, under the irradiation of the laser spot emitter (8), the support layer (4) material completes the imidization and curing process and is transformed into a polyimide material.

19. The molding method for polyimide engineering parts as described in claim 1, characterized in that, In S5, the upper surface of the uppermost support layer is used as the surface of the molding platform in S2. The position of the molding platform is adjusted to form a liquid film of a set thickness on the upper surface of the uppermost support layer.

20. The molding method for polyimide engineering parts as described in claim 1, characterized in that, In S6, ultrasonic treatment was performed in the reagent to detach the support layer material that had not completed the imidization and curing process from the surface of the final part.

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