A pipe dip forming device and method

Abstract

This invention discloses a pipe dip-coating forming apparatus and method, comprising: a storage bottle for holding a dip-coating solution; the interface of the storage bottle is connected to the input end of a peristaltic pump via a first conduit, and the output end of the peristaltic pump is connected to a storage die head via a second conduit; a pay-off shaft, the output end of which passes a wound mandrel through the storage die head for dip-coating, and after curing in a sintering furnace, it is transported to a take-up shaft; the peristaltic pump quantitatively delivers the dip-coating solution, the speed of the peristaltic pump being correlated with the speed of the take-up shaft to reduce the damage to the polymer chains caused by shearing; the storage bottle and the storage die head are protected by nitrogen gas to prevent the dip-coating solution from contacting moisture during the dip-coating process, thus maintaining the stability of the dip-coating solution quality.

Description

Technical Field

[0001] This invention relates to the field of medical tubing manufacturing technology, and in particular to a tubing dip-coating molding apparatus and method. Background Technology

[0002] Dip coating is a process in which the object to be coated is completely immersed in a liquid coating, then removed and allowed to flow back into the tank naturally, thus forming a uniform coating film on the surface. In the manufacturing process of medical tubing, coatings with different properties can be prepared by controlling the composition of the dipping solution. However, some highly reactive dipping solutions, which readily react with water or oxygen in the air, may slowly deteriorate during production, affecting the performance of the tubing.

[0003] For example, in the production process of polyimide (PI) tubes, it is necessary to replenish the precursor polyamic acid (PAA) solution regularly and in measured quantities. The main reason is that PAA solution has a high viscosity and is a non-Newtonian fluid, which thins under shear. On the other hand, PAA solution is extremely sensitive to moisture and easily reacts with moisture in the air. Exposure to air can cause molecular chain breakage, resulting in decreased viscosity or even deterioration.

[0004] Adding too much solution at once results in prolonged contact with air, causing the solution to react with water and affecting the quality of the finished product. Adding small amounts multiple times, and frequently opening the seal of the storage bottle, will also accelerate solution deterioration, easily leading to inconsistent performance of the produced PI tubes. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a pipe dip coating forming apparatus and method.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: a pipe dip-coating forming apparatus, comprising: Storage bottle, used to hold dipping solution; The interface of the storage bottle is connected to the input end of the peristaltic pump through a first conduit, and the output end of the peristaltic pump is connected to the storage mold head through a second conduit. The output end of the pay-off spool passes the mandrel being wound through the liquid storage mold head for immersion coating. After being cured and formed in a sintering furnace, it is then transported to the take-up spool.

[0007] As a further description of the above technical solution: the interface of the liquid storage bottle is also provided with a third conduit, one end of which extends into the inside of the liquid storage bottle and is located above the surface of the immersion liquid, and the other end is connected to the gas storage component.

[0008] As a further description of the above technical solution: the liquid storage mold head is provided with an outwardly extending air inlet, through which protective gas is introduced into the liquid storage mold head.

[0009] As a further description of the above technical solution: a plurality of guide reels are provided between the pay-off shaft and the take-up shaft, and the mandrel is guided by the guide reels and passes through the liquid storage mold head and the sintering furnace.

[0010] As a further description of the above technical solution: the first conduit and the second conduit are rubber tubes, the third conduit is a glass tube, and the liquid storage bottle is a brown glass bottle.

[0011] As a further description of the above technical solution: the dip coating solution is a precursor polyamic acid solution.

[0012] It also includes a pipe dip coating molding method, comprising: Add the coating solution into the storage bottle, and introduce protective gas into the storage bottle and the storage mold head through the third conduit and the air inlet, respectively. The immersion coating liquid in the storage bottle is transported to the storage mold head by a peristaltic pump until the immersion coating liquid in the storage mold head reaches the preset liquid level. The mandrel output from the pay-off shaft is passed through the liquid storage mold head and the sintering furnace in sequence via the guide plate, so that the other end of the mandrel is wound around the take-up shaft. Control the rotation of the take-up shaft to wind up the material, so that the outer side of the mandrel is impregnated and cured to form a tube.

[0013] As a further description of the above technical solution: the rotation speed of the peristaltic pump is adjusted according to the rotation speed of the winding shaft to stabilize the liquid level in the liquid storage head.

[0014] As a further description of the above technical solution: the preset liquid level height is at 2 / 3 of the height of the liquid storage mold head.

[0015] As a further description of the above technical solution: the protective gas is nitrogen with a purity of 99.99% and an input flow rate of 5-10 L / min.

[0016] The above technical solution has the following advantages or beneficial effects: The dipping solution is metered and delivered using a peristaltic pump, with the pump speed correlated with the take-up spindle speed, reducing the damage to the polymer chains caused by shearing. The storage bottle and the storage die are protected with nitrogen gas to prevent the dipping solution from coming into contact with moisture during the dipping process, thus maintaining the stability of the dipping solution quality. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of the molding device proposed in this invention. Figure 2 This is a flowchart of the molding method proposed in this invention.

[0019] Legend: 1. Liquid storage bottle; 2. First conduit; 3. Peristaltic pump; 4. Second conduit; 5. Liquid storage die head; 6. Pay-off spool; 7. Mandrel; 8. Sintering furnace; 9. Take-up spool; 10. Third conduit; 11. Gas storage component; 12. Air inlet; 13. Wire reel. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] Reference Figure 1 An embodiment of the present invention provides a pipe dip coating forming device, comprising: a liquid storage bottle 1 for holding dip coating liquid; the interface of the liquid storage bottle 1 is connected to the input end of a peristaltic pump 3 through a first conduit 2, and the output end of the peristaltic pump 3 is connected to a liquid storage die head 5 through a second conduit 4; a wire feeding shaft 6, the output end of which passes a wound mandrel 7 through the liquid storage die head 5 for dip coating, and after being cured and formed by a sintering furnace 8, it is transported to a take-up shaft 9.

[0022] In this embodiment, the impregnation solution, a precursor polyamic acid (PAA) solution, is placed inside the storage bottle 1. The storage bottle 1 is made of brown glass to protect it from light. The first conduit 2 connects the storage bottle 1 to the input end of the peristaltic pump 3, and the second conduit 4 connects the output end of the peristaltic pump 3 to the storage mold head 5. The first conduit 2 and the second conduit 4 are rubber tubes, which stably deliver the impregnation solution into the storage mold head 5. The peristaltic pump 3 uses a large diameter and low speed, with an inner diameter of 4-8 mm and a flow rate controlled at 0.5-5 ml / min to deliver the high-viscosity non-Newtonian fluid with low shear force, avoiding damage to the molecular chains by shear force.

[0023] The interface of the liquid storage bottle 1 is also provided with a third conduit 10. One end of the third conduit 10 extends into the inside of the liquid storage bottle 1 and is located above the surface of the immersion liquid, while the other end is connected to the gas storage component 11.

[0024] In this embodiment, the third conduit 10 is a glass tube. One end of the third conduit 10 is placed above the liquid surface in the liquid storage bottle 1, and the other end is connected to the gas storage device 11. Protective gas is filled into the liquid storage bottle 1 through the gas storage device 11 to replace the air, isolate water vapor, and ensure the stability of the quality of the coating solution. The gas storage device 11 is a gas bag filled with nitrogen.

[0025] The liquid storage mold head 5 is provided with an outwardly extending air inlet 12, through which protective gas is introduced into the liquid storage mold head 5.

[0026] In this embodiment, an air inlet 12 is provided above the liquid storage mold head 5. Nitrogen gas is continuously introduced into the liquid storage mold head 5 through the air inlet 12 to keep the interior of the liquid storage mold head 5 in a nitrogen atmosphere at all times, so as to prevent the coating liquid from deteriorating upon contact with air.

[0027] Several wire guides 13 are arranged between the wire feeding spool 6 and the wire taking spool 9. The mandrel 7 is guided by the wire guides 13 and passes through the liquid storage mold head 5 and the sintering furnace 8.

[0028] In this embodiment, several wire reels are provided between the pay-off spool 6 and the take-up spool 9. The pay-off spool 6 outputs and releases the mandrel 7. The mandrel 7 serves as the tube forming substrate and is guided and transported by the wire reels 13. The mandrel 7 passes through the liquid storage die 5 and the sintering furnace 8 in sequence. A layer of PAA solution is dipped into the outside of the mandrel 7 through the liquid storage die 5. Then, it enters the sintering furnace 8, where the dipped mandrel 7 is heated and cured to complete the imidization reaction and form a tube.

[0029] Reference Figure 2 It also includes a pipe dip-coating molding method, comprising: S1. Add the coating solution into the storage bottle, and introduce protective gas into the storage bottle and the storage mold head through the third conduit and the air inlet, respectively. S2. The dipping solution in the storage bottle is transported to the storage mold head by a peristaltic pump until the dipping solution in the storage mold head reaches the preset liquid level. S3. Pass the mandrel output from the pay-off shaft through the guide plate in sequence through the liquid storage mold head and the sintering furnace, so that the other end of the mandrel is wound around the take-up shaft. S4. Control the rotation of the take-up shaft to wind up the core, so that the outer side of the core is coated and cured to form a tube.

[0030] In this embodiment, the coating solution is stored in a brown storage bottle 1, and the third conduit 10 is inserted into the storage bottle 1 through a rubber stopper. At this time, the third conduit 10 is placed above the liquid surface. Nitrogen gas is introduced from the gas storage device 11 connected to the other end of the third conduit 10 to replace the air in the storage bottle 1 with nitrogen gas. Then, the first conduit 2 is inserted below the liquid surface, and the third conduit 10 remains connected to the gas storage device 11. Under the protection of nitrogen gas, the coating solution is slowly transported to the storage mold head 5 by the peristaltic pump 3. Nitrogen gas is continuously introduced through the air inlet 12 of the storage mold head 5 to maintain a nitrogen atmosphere in the cavity of the storage mold head 5, thus isolating the coating solution from contact with moisture in the air.

[0031] The peristaltic pump 3 delivers the dipping solution in the storage bottle 1 to the storage mold head 5. Dipping begins when the liquid level of the dipping solution reaches the preset liquid level height.

[0032] The mandrel 7, output from the pay-off spool 6, is directionally pulled through the guide plate 13, passing sequentially through the impregnation liquid in the liquid storage die 5, and entering the sintering furnace 8 for imidization reaction. After exiting the sintering furnace 8, it is naturally cooled to room temperature and then wound onto the take-up spool 9 for winding and positioning. After cooling to room temperature, the mandrel 7 can be thinned, and pulling it out yields the tube. The thickness of the mandrel 7 determines the inner diameter of the tube, and the amount of impregnation liquid adhering to the surface of the mandrel 7 determines the wall thickness of the tube.

[0033] Once the mandrel 7 is being conveyed at a constant speed, the parameters of the peristaltic pump 3 are adjusted to ensure a stable delivery of the coating solution, keeping the liquid level in the storage mold head 5 stable for continuous production. After production is completed, the PAA solution is washed away with N,N-dimethylacetamide (DMA), N-methyl-2-pyrrolidone (NMP), and N,N-dimethylformamide (DMF), followed by ethanol cleaning and drying.

[0034] Adjust the speed of the peristaltic pump according to the speed of the winding shaft to stabilize the liquid level in the storage die.

[0035] In this embodiment, when the machine starts running, the conveying speed of the mandrel 7 gradually increases, and the more immersion coating liquid is carried away by the immersion coating, the faster the rotation speed of the peristaltic pump 3 becomes, thereby increasing the amount of immersion coating liquid conveyed and maintaining a stable liquid level. When the mandrel 7 runs at a constant speed, the conveying flow rate of the peristaltic pump 3 is maintained at the preset liquid level.

[0036] The preset liquid level is 2 / 3 of the height of the liquid storage mold head.

[0037] In this embodiment, the dipping coating begins after the dipping liquid reaches the preset liquid level. The preset liquid level is 2 / 3 higher than the height of the liquid storage mold head 5, and the height of the dipping liquid level is ensured to be lower than the air inlet 12.

[0038] The protective gas is nitrogen with a purity of 99.99% and an input flow rate of 5-10 L / min.

[0039] In this embodiment, a protective gas is introduced into the liquid storage mold head 5 to maintain a nitrogen atmosphere inside the cavity of the liquid storage mold head 5. The nitrogen flow rate should be slow and continuous, the nitrogen purity should be 99.99%, and the nitrogen flow rate should be 5-10 L / min, thereby achieving the purpose of isolating the coating liquid from moisture in the air.

[0040] In one specific embodiment Nitrogen gas was not introduced into the storage mold 5. The PAA solution in the container was manually added to the storage mold 5 to maintain the amount of PAA solution in the storage mold 5. The other conditions remained the same as in this embodiment. After running for ten hours, the sample was collected, and the sampling results are as follows:

[0041] The results show that the mechanical properties of the pipes decreased after long-term operation. This is because the PAA solution reacts with water, causing the PAA molecular chains to break, which in turn worsens the mechanical properties of the product.

[0042] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0043] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A pipe dip forming apparatus characterized by comprising: include: Storage bottle (1), used to hold the dipping solution; The interface of the storage bottle (1) is connected to the input end of the peristaltic pump (3) through the first conduit (2), and the output end of the peristaltic pump (3) is connected to the storage mold head (5) through the second conduit (4). The output end of the pay-off shaft (6) passes the wound mandrel (7) through the liquid storage mold head (5) for immersion coating, and after being solidified and formed by the sintering furnace (8), it is transported to the take-up shaft (9).

2. The forming device of claim 1, wherein: The interface of the liquid storage bottle (1) is also provided with a third conduit (10). One end of the third conduit (10) is inserted into the inside of the liquid storage bottle (1) and located above the surface of the immersion liquid, and the other end is connected to the gas storage component (11).

3. The forming device of claim 1, wherein: The liquid storage mold (5) is provided with an outwardly extending air inlet (12), through which protective gas is introduced into the liquid storage mold (5).

4. The forming device of claim 1, wherein: A plurality of wire reels (13) are provided between the wire feeding shaft (6) and the wire taking shaft (9). The mandrel (7) is guided by the wire reels (13) and passes through the liquid storage mold head (5) and the sintering furnace (8).

5. The forming device of claim 2, wherein: The first conduit (2) and the second conduit (4) are rubber tubes, and the third conduit (10) is a glass tube.

6. The forming device of claim 3, wherein: The coating solution is a precursor polyamic acid solution.

7. A method for dip coating molding of pipes, characterized in that, include: Add the coating solution into the storage bottle, and introduce protective gas into the storage bottle and the storage mold head through the third conduit and the air inlet, respectively. The immersion coating liquid in the storage bottle is transported to the storage mold head by a peristaltic pump until the immersion coating liquid in the storage mold head reaches the preset liquid level. The mandrel output from the pay-off shaft is passed through the liquid storage mold head and the sintering furnace in sequence via the guide plate, so that the other end of the mandrel is wound around the take-up shaft. Control the rotation of the take-up shaft to wind up the material, so that the outer side of the mandrel is impregnated and cured to form a tube.

8. The molding method according to claim 7, characterized in that: The rotation speed of the peristaltic pump is adjusted according to the rotation speed of the winding shaft to stabilize the liquid level in the liquid storage head.

9. The molding method according to claim 7, characterized in that: The preset liquid level is at 2 / 3 of the height of the liquid storage mold head.

10. The molding method according to claim 7, characterized in that: The protective gas is nitrogen with a purity of 99.99% and an input flow rate of 5-10 L / min.

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