A liquid delivery conduit and method of forming the same

Abstract

The application discloses a liquid conveying pipeline capable of being shaped at will and a forming method thereof, and belongs to the technical field of pipelines. The pipeline is sequentially composed of a flow channel layer, a metal-elastic body supporting layer and a wear-resistant protective layer from inside to outside. The flow channel layer is composed of a polyether type polyurethane base material, surface carboxyl modified silver doped nano titanium dioxide, transparent nematic phase liquid crystal microbeads and adipic acid dihydrazide coupling agents, and the inner surface of the polyurethane base material is etched by ammonia plasma to form shallow dish-shaped nano pits. The metal-elastic body supporting layer comprises a plurality of stainless steel wires and a thermoplastic polyurethane matrix crosslinked by a urea-based pyrimidone-polyethylene glycol composite crosslinking agent, and the matrix is dispersed with two kinds of microcapsules with polyaspartic acid and polysiloxane as core materials. The wear-resistant protective layer is composed of a thermoplastic TPE-ST base material, nano zinc oxide and polytetrafluoroethylene micro powder. The pipeline has the flexible shaping capability, is not easy to be folded and blocked, and can be adapted to multiple scenes such as medical infusion, gardening drip irrigation, industrial disinfectant water conveying and the like.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of pipelines, in particular to a liquid conveying pipeline capable of being shaped at will and a forming method thereof. BACKGROUND

[0002] As a key carrier for liquid transmission, the flexible conveying pipeline has been widely used in industrial production, people's livelihood application and other fields due to its characteristics of being bendable and adaptable to complex spaces. Its transmission stability and use convenience directly affect production efficiency, experimental accuracy and use experience. With the increasing demand for accurate, smooth and flexible liquid transmission in various fields, the application scenarios of the flexible conveying pipeline continue to expand, but the performance shortfalls of existing products still restrict their further promotion.

[0003] In the industrial production scene, the disinfectant water conveying pipeline in the food processing process is a typical application, which needs to shuttle between the gaps of production line equipment to ensure uniform transmission of disinfectant water to protect food hygiene; the people's livelihood application scenarios include medical infusion tubes and gardening precise drip irrigation pipelines — medical infusion tubes are core components of clinical intravenous infusion, which need to be fitted to the patient's posture to ensure smooth delivery of liquid medicine, and the gardening precise drip irrigation pipeline needs to be bent around the plant stem to realize directional supply of water and fertilizer.

[0004] The existing flexible conveying pipeline (such as ordinary PVC soft pipe, rubber pipe, etc.) has common shortfalls in the above-mentioned scenarios. Among them, the most prominent problem is easy to collapse and block liquid, and the pipeline is easy to form a dead fold when bent, which causes the pipe cavity to collapse, and then causes the liquid conveying to be interrupted or the flow resistance to be suddenly changed, affecting the stability and accuracy of transmission; secondly, the problem of insufficient versatility is also obvious, and the existing pipeline is designed for a single use scenario, and the material and structure are difficult to adapt to different types of transmission medium or use environment, and the cross-scene adaptation ability is limited. These problems make it difficult for the existing flexible conveying pipeline to fully meet the core needs of smooth and flexible adaptation of liquid transmission in various fields.

[0005] Therefore, it is urgent to provide a liquid conveying pipeline capable of being manually bent and stably maintaining shape, not easy to collapse and block liquid, and having a certain versatility, and a forming method thereof. SUMMARY

[0006] The purpose of the present application is to provide a liquid conveying pipeline capable of being shaped at will and a forming method thereof, to solve the problems of easy collapse and blockage of liquid, insufficient versatility and poor transmission stability of the existing flexible conveying pipeline, and to meet the liquid transmission needs of multiple scenarios such as medical, gardening and industry.

[0007] The purpose of the present application is achieved by the following technical solutions:

[0008] A liquid conveying pipeline capable of being shaped at will, comprising a flow channel layer, a metal-elastic body support layer and a wear-resistant protective layer which are sequentially compounded from inside to outside;

[0009] The flow channel layer is composed of a polyether polyurethane (PU) substrate, transparent nematic liquid crystal microbeads modified by surface carboxyl groups, silver-doped nano-titanium dioxide (Ag-TiO2) modified by surface carboxyl groups, and adipic acid dihydrazide coupling agent.

[0010] The inner surface of the PU substrate is etched by ammonia plasma to form shallow dish-shaped nano-pits;

[0011] The metal-elastomer support layer comprises a plurality of double helix wavy stainless steel wires and a thermoplastic polyurethane (TPU) matrix;

[0012] The stainless steel wires are spirally wound at equal angles;

[0013] The TPU matrix is crosslinked by a urea-based pyrimidone (UPy)-polyethylene glycol (PEG) composite crosslinking agent, and dispersed with two kinds of microcapsules with core materials of polyaspartic acid and polysiloxane;

[0014] The wear-resistant protective layer is composed of a thermoplastic TPE-ST substrate, nano-zinc oxide, polytetrafluoroethylene micro-powder, and nano-silica whiskers grafted with KH-560 silane coupling agent on the surface.

[0015] As some embodiments of the present application, the thickness of the flow channel layer is 0.1mm~0.3mm, wherein the addition amount of the liquid crystal microbeads modified by surface carboxyl groups is 1.5~2.5wt%; the addition amount of the silver-doped nano-titanium dioxide modified by surface carboxyl groups is 0.6~1.0wt%; the addition amount of the adipic acid dihydrazide coupling agent is 0.3~0.7wt%; the opening diameter of the nano-pits is 0.5μm~1.0μm, and the depth is 0.2μm~0.4μm.

[0016] As some embodiments of the present application, the thickness of the metal-elastomer support layer is 0.2~0.5mm, wherein the stainless steel wires are 3~5 in number, and the diameter is 0.05~0.10mm.

[0017] As some embodiments of the present application, in the thermoplastic polyurethane matrix, the addition amount of the urea-based pyrimidone-polyethylene glycol composite crosslinking agent is 2~4wt%; the addition amount of the two kinds of microcapsules is both 0.4wt%~1.2wt%, and the particle size is 1μm~10μm.

[0018] As some embodiments of the present application, the wear-resistant protective layer has a thickness of 0.1mm-0.35mm, wherein the nano-silica whisker has an addition amount of 4wt%-8wt% and a particle size of 0.04μm-0.12μm; the nano-zinc oxide has an addition amount of 0.8wt%-1.2wt% and a particle size of 30nm-80nm; and the polytetrafluoroethylene micro-powder has an addition amount of 0.3wt%-0.7wt% and a particle size of 0.8μm-2.5μm.

[0019] As some embodiments of the present application, the wall materials of the two microcapsules are both gradient wall thickness structures, the outer layer is polyethylene glycol-polyurea formaldehyde with a wall thickness of 80nm-120nm, and the inner layer is polylactic acid-polycaprolactone with 0.3wt%-0.7wt% nano-montmorillonite added, and the inner layer has a wall thickness of 400nm-600nm.

[0020] The present scheme can adapt to different fluid scenarios, such as low-viscosity physiological saline and dilute disinfectant water, which have small shear force and can only trigger the rupture of the outer layer to release a small amount of ingredients to meet the basic needs; high-viscosity parenteral nutrition preparations and high-concentration water and fertilizer, which have significantly increased shear force and can penetrate the outer layer and trigger the rupture of the inner layer together to release sufficient ingredients to inhibit fouling and residue; Chinese medicine decoction and organic water and fertilizer containing particles, which have particle impact force superimposed on shear force, and the nano-montmorillonite added in the inner layer can enhance the wear resistance of the wall material and reduce the damage of particles to the microcapsule wall, to a certain extent, alleviating the problem of insufficient functional adaptability caused by multiple types of fluids, which can adapt to the transmission requirements of different medical liquids in medical infusion scenarios, and can also meet the use requirements of industrial cleaning, gardening drip irrigation and other scenarios.

[0021] As some embodiments of the present application, the stainless steel wire is coated with a 0.03mm-0.06mm dopamine-tannin-zinc phosphate composite coating, and the coating is grafted with poly-caprolactone (PCL) shape memory polymer brushes.

[0022] In actual implementation, the metal-elastic support layer is between the flow channel layer and the wear-resistant protective layer, and the stainless steel wire itself does not directly contact the transmission fluid, but in the medical infusion, industrial cleaning and garden drip irrigation scenarios, corrosive components may still indirectly act on the stainless steel wire due to the interfacial or structural micro-damage: in the medical infusion scenario, if the flow channel layer generates micro-cracks due to repeated bending (such as the patient turning over or moving the infusion stand for adjustment), acidic drug solution (vitamin C injection, citric acid buffer), alkaline drug solution (sodium bicarbonate injection, aminophylline injection) or residual sodium hypochlorite solution after disinfection may penetrate into the support layer through the cracks; in the industrial cleaning scenario, if the protective layer is worn due to the dragging of the production line, disinfectant water is easy to penetrate through the wear; in the garden drip irrigation scenario, salt-containing water and fertilizer may slowly penetrate through the joint gap of the protective layer, and these penetrating corrosive components will gradually act on the stainless steel wire. At the same time, the medical infusion tube needs to be frequently bent with the patient's body position, the industrial pipe is repeatedly stressed when shuttling between equipment, and the garden pipe is repeatedly stressed when winding and laying, which are easy to cause elastic fatigue of the stainless steel wire, and further damage the synergistic support of the TPU matrix.

[0023] The present application coats a dopamine-tannic acid-zinc phytate composite coating on the surface of the stainless steel wire. The zinc phytate can form a stable passivation film on the surface of the stainless steel wire to block the penetration of corrosive components from directly contacting the stainless steel wire. If the coating is damaged due to internal stress of the support layer, the ortho-phenolic group of dopamine can self-assemble with the hydroxyl group of tannic acid and the metal ion of zinc phytate through dynamic hydrogen bonding and coordination bonding to repair the damage and avoid further corrosion. At the same time, the coating grafts polycaprolactone (PCL) shape memory polymer brushes, which crystallize and lock the shape of the stainless steel wire in the low-temperature environment (2-8℃) of medical cold storage and transportation; when the pipe contacts the human body (37℃) or is assisted by warm water (about 60℃), the PCL near the melting point dissociates from the crystalline state, releases internal stress, and reduces plastic deformation of the stainless steel wire. Note: The melting point of PCL is 58-63℃, and the human body temperature can make PCL in a semi-crystalline-melting transition state, which can realize internal stress release when the pipe is used with slight external force (such as body position adjustment).

[0024] As some implementable modes of the present application, the adipic acid dihydrazide coupling agent of the flow channel layer is replaced by a poly-N-isopropyl acrylamide (PNIPAM)-adipic acid dihydrazide composite coupling agent, and the PCL shape memory polymer brushes of the stainless steel wire coating add 0.2wt%-0.4wt% carbon quantum dots, and the TPU matrix adds 0.3wt%-0.7wt% polyethylene glycol monomethyl ether (mPEG).

[0025] In actual implementation, the pipe in the medical scene needs to undergo temperature fluctuations of refrigerated transportation (2-8℃, such as biological preparation infusion pipe), human body temperature environment (37℃, infusion use), and the industrial scene may face temperature changes in the workshop, and the horticulture scene has day and night temperature difference. These temperature fluctuations are easy to cause the response of the flow channel layer coupling, the shape memory function of the stainless steel wire coating and the crosslinking network of the TPU matrix to be out of sync - the pipe is easy to hard fold (which may compress blood vessels or interrupt infusion, and the hard fold will also affect the transmission in the industrial and horticulture scenes) at low temperature, and the synergistic support effect is weakened (the pipe cavity is easy to collapse) at high temperature. The application adjusts the temperature change response threshold of the flow channel layer by replacing the adipic acid dihydrazide coupling agent of the flow channel layer with a poly-N-isopropyl acrylamide-adipic acid dihydrazide composite coupling agent (which is suitable for the medical temperature range); adds carbon quantum dots in the polycaprolactone shape memory polymer brush of the stainless steel wire coating to assist in adjusting the shape memory response speed; and adds polyethylene glycol monomethyl ether in the TPU matrix to enhance the temperature change synergy of the TPU and the stainless steel wire and the flow channel layer, so that the flow channel layer, the stainless steel wire coating and the TPU matrix respond more consistently in the common temperature range, avoiding the influence of low-temperature hard folding on the safety of medical infusion and the transmission stability of industrial and horticulture scenes, and preventing support failure caused by high-temperature softening, thereby improving the stability of the pipe in medical refrigerated transportation, clinical use, industrial cleaning and horticulture outdoor scenes.

[0026] In addition, in order to achieve the above-mentioned purpose, the application further provides a forming method of a liquid conveying pipe capable of being shaped at will, comprising the following steps:

[0027] S1. Carboxyl modification is performed on the surface of silver-doped nano-titanium dioxide and transparent nematic liquid crystal microbeads, and then the modified silver-doped nano-titanium dioxide and transparent nematic liquid crystal microbeads are mixed with polyether polyurethane base material and adipic acid dihydrazide coupling agent, and then the mixture is melt-extruded at 160-200°C to form shallow dish-shaped nano-pits on the inner surface of the extruded base material by using an ammonia plasma etching device, thereby obtaining a flow channel layer.

[0028] S2. The stainless steel wire is pre-formed into a double helix wave shape, and the pitch is wound on the outer surface of the flow channel layer. Meanwhile, thermoplastic polyurethane matrix, urea-based pyrimidone-polyethylene glycol composite crosslinking agent and two kinds of microcapsules are mixed, and then the mixture is melt-composite extruded at 180-210°C to coat the outside of the stainless steel wire, thereby forming a support layer.

[0029] S3. TPE-ST base material, nano-zinc oxide, polytetrafluoroethylene micro powder and nano-silica whisker grafted with KH-560 are mixed, and then the mixture is melt-extruded at 170-205°C to coat the outer surface of the support layer, and then the mixture is cooled and traction shaped to obtain a finished product.

[0030] As some embodiments of the present application, in step S1, the ammonia plasma etching power is 300W-500W, and the etching time is 40s-80s; in step S3, the cooling is carried out by subsection cooling, and the cooling parameters are as follows: the front section is 55-65 DEG C, and the rear section is 25-30 DEG C.

[0031] Compared with the prior art, the beneficial effects of the present application are:

[0032] The present application effectively improves the problems of easy folding and blocking of liquid, insufficient versatility and poor transmission stability of the flexible conveying pipeline in the background art through the synergistic effect of the flow channel layer, the metal-elastic support layer and the wear-resistant protective layer, as follows:

[0033] In the flow channel layer, the polyether type PU substrate itself has good flexibility and biocompatibility, and is a suitable substrate selection for medical infusion tubes. Its softness can adapt to the bending requirements when the patient adjusts the body position. The amino group introduced by ammonia plasma is cross-linked with the carboxyl group on the surface of the carboxyl-modified Ag-TiO2 and the carboxyl-modified liquid crystal microbeads through the bifunctional groups (one end reacts with amino group and one end reacts with carboxyl group) of adipic dihydrazide coupling agent to form stable amide bonds. This chemical bonding method reduces the free migration of nano components in the substrate, not only alleviates the problems of easy aggregation and uneven dispersion of nanoparticles to some extent, but also reduces the risk of flow channel blockage caused by cross-layer aggregation, and helps to continuously and stably exert the functions of antibacterial and lubrication. Ag-TiO2 as a broad-spectrum antibacterial component can inhibit the growth of common pathogenic bacteria such as Escherichia coli and Staphylococcus aureus in medical treatment, and the synergistic effect of silver ions and TiO2 improves the corrosion resistance of the component, which can adapt to the corrosion environment of acidic / alkaline liquid medicine, disinfectant water and horticultural sulfur-containing water and fertilizer in medical treatment, not only reducing the risk of infection caused by bacterial growth during infusion, but also reducing the functional degradation caused by corrosion of corrosive fluid; the carboxyl-modified liquid crystal microbeads optimize the lubricity of the inner wall of the flow channel, and reduce the transmission resistance of high-viscosity liquid medicine (such as nutrient solution and traditional Chinese medicine preparation); the interface mechanical interlocking structure formed by the shallow dish-shaped nanometer pits can also enhance the physical combination of the flow channel layer and the support layer, and alleviate the phenomenon of easy peeling of the interface of heterogeneous materials.

[0034] In the metal-elastic support layer, the TPU matrix is cross-linked by the UPy-PEG composite cross-linking agent and dispersed with two kinds of microcapsules of polyaspartic acid and polysiloxane. The double helix wave-shaped 316L stainless steel wire builds a three-dimensional support network under the premise of ensuring the flexibility of the pipeline, which helps to reduce the collapse of the lumen caused by dead folding when the pipeline is bent, and alleviates the problem of interrupting infusion due to folding caused by body position adjustment of the existing infusion tube. At the same time, it meets the use requirements of complex scenes such as industrial wiring and gardening winding; the double helix structure of the stainless steel wire can also disperse the stress when bending, reduce the elastic fatigue caused by single direction stress, and prolong the service life of the pipeline. The UPy-PEG composite cross-linking agent gives the TPU matrix unique dynamic cross-linking characteristics. The reversible quadruple hydrogen bonds formed between UPy molecules and the PEG flexible chain segment cooperate with each other. In low temperature environment, the hydrogen bond is locked to maintain the network rigidity, reducing the influence of TPU brittle fracture on infusion safety. In high temperature environment, the hydrogen bond is dissociated, and the PEG segment is stretched to maintain flexibility, which helps the pipeline to be shaped at will and to stably maintain the morphology. This temperature change adaptation characteristic makes the pipeline adapt to different temperature scenes such as medical transportation and storage, outdoor gardening, etc. The two kinds of microcapsules dispersed in the TPU matrix play different roles: the polyaspartic acid microcapsule can inhibit the scaling and deposition of calcium and magnesium ions in the drug solution or water fertilizer, reduce the risk of pipeline wall scaling and blockage in the long-term infusion process, and ensure the flow stability of infusion or drip irrigation; the polysiloxane microcapsule reduces the wall adhesion of viscous medium, improves the cleanliness of the pipeline, and reduces the risk of clinical cross contamination or industrial medium residue. The synergistic effect of the two kinds of microcapsules expands the adaptation ability of the pipeline to different types of media.

[0035] In the wear-resistant protective layer, the TPE-ST substrate has flexibility and wear resistance, which can reduce the friction damage of the pipeline and the skin and equipment during clinical operation, resist wear caused by industrial production line dragging and gardening support friction, and prolong the service life of the pipeline; nano silicon whiskers further enhance the wear resistance of the protective layer and improve the mechanical strength of the pipeline. PTFE micro powder optimizes the lubricity of the surface of the protective layer, facilitating the insertion, adjustment and industrial pipeline dragging and laying of the infusion tube, and reducing the operation resistance in the use process; the KH-560 silane coupling agent forms a stable cross-layer bonding network through the hydrogen bond between the epoxy group and the hydroxyl group of the support layer TPU, which alleviates the interlayer peeling phenomenon of the multi-layer composite pipeline after repeated bending and sterilization treatment, and helps to ensure the structural integrity of the medical infusion tube during sterilization, transportation and use. Nano zinc oxide has a mild anti-ultraviolet property, which helps to reduce the aging damage of the pipeline material caused by ultraviolet rays in outdoor gardening drip irrigation scenes, and its non-toxic property meets the safety requirements of medical and food contact materials, which will not adversely affect the stability of the drug solution or the quality of the water and fertilizer, and meets the use requirements of multiple scenes.

[0036] In summary, the three-layer composite structure and the component and structure of each layer of the present application not only effectively improve the problems of easy folding, poor universality and insufficient transmission stability of the existing flexible conveying pipeline, but also alleviate the derived problems of nano-component aggregation, interlayer peeling, bacterial breeding, drug solution residue, scaling and blocking, etc. Finally, the pipeline presents the comprehensive performance of flexible shaping, not easy to fold, safe and clean, and adaptation to multiple media, which not only meets the strict safety requirements of medical infusion tubes, but also adapts to the use scenarios of industrial medium conveying, gardening drip irrigation and other fields, thereby expanding the application range of flexible liquid conveying pipeline. DETAILED DESCRIPTION

[0037] Example 1: Prepare a medical infusion tube for medical scenarios.

[0038] S1. Preparation of flow channel layer: weigh polyether type PU base material (medical grade, Shore hardness 60A) 96.7%, surface carboxyl modified liquid crystal microbeads 2.0%, surface carboxyl modified Ag-TiO2 0.8%, adipic dihydrazide coupling agent 0.5% according to the mass ratio, mix and put into a double screw extruder, melt extrude at 180℃; etch to form shallow dish-shaped nano pits (reduce drug solution residue) with an opening diameter of 0.8μm and a depth of 0.3μm by introducing amino groups simultaneously through an ammonia plasma etching device (power 400W, time 60s), to obtain a flow channel layer with a thickness of 0.2mm and an inner diameter of 2.5mm.

[0039] Preparation of the surface carboxyl modified Ag-TiO2: (1) using sol-gel method, take tetrabutyl titanate 100mL dissolved in 500mL anhydrous ethanol, stir for 30min to obtain A liquid; take silver nitrate 0.8g dissolved in 100mL deionized water, drop 1mol / L nitric acid to adjust pH=2 to obtain B liquid; add all B liquid drop by drop into A liquid (drop rate 2mL / min), 60℃ constant temperature water bath stirring for 2h, aging for 12h, then calcining at 500℃ in a muffle furnace for 2h, grinding to obtain Ag-TiO2 powder with particle size of 50nm.

[0040] (2) take the above Ag-TiO2 powder 5g, add 100mL deionized water, ultrasonic dispersion for 30min (power 300W) to form a suspension; add citric acid (analytical pure) 1.0g, adjust pH=5.5, 70℃ constant temperature water bath stirring for 4h; after the reaction is completed, centrifugal collection of solid, washing with deionized water for 3 times, 80℃ vacuum drying for 6h, to obtain surface carboxyl modified Ag-TiO2 powder.

[0041] Preparation of the surface carboxyl modified liquid crystal microbeads: take liquid crystal microbeads 2g (particle size 0.8μm, medical grade transparent nematic phase), add 50mL anhydrous ethanol, ultrasonic dispersion for 20min, add 0.5g maleic anhydride (medical grade), 60℃ stirring for 3h, centrifugal washing and vacuum drying to obtain surface carboxyl modified liquid crystal microbeads.

[0042] Note: The above carboxyl modification can also be modified by other conventional methods.

[0043] S2. Support layer composite: 4 pieces of 316L stainless steel wire (diameter 0.08 mm, medical grade non-magnetic) were pressed into double helical wave shape (wave height 0.2 mm) by roller; wound on the outer surface of the flow channel layer at an equal angle of 90° and a pitch of 12 mm (to ensure that the lumen cross-sectional area retention rate is ≥95% when bending); according to the mass ratio, medical grade TPU base material (Shore hardness 70A) 96.0%, UPy-PEG complex crosslinking agent 3.0%, polyaspartic acid microcapsule 0.5%, polysiloxane microcapsule 0.5% were weighed; after mixing, melt composite extrusion at 195°C, coated on the outside of the stainless steel wire, and a support layer with a thickness of 0.3 mm was obtained.

[0044] The method of polyaspartic acid microcapsule is as follows:

[0045] (1) Raw material preparation:

[0046] Core material solution preparation: Take 3 g of medical grade polyaspartic acid (molecular weight 3000), add 30 mL of deionized water, and stir until completely dissolved; then add 0.15 g of Tween-80, ultrasonic dispersion for 15 min (power 300 W), to form a uniform polyaspartic acid core material solution.

[0047] Outer layer spinning solution preparation: Take polyethylene glycol (PEG, molecular weight 2000) 1.7 g, polyurea formaldehyde 2.3 g according to the mass ratio of 1:2, mix and add 100 mL of N,N-dimethylformamide (DMF), stir in a constant temperature water bath at 60°C for 2 h, until completely dissolved, to obtain a transparent outer layer spinning solution;

[0048] Inner layer spinning solution preparation: Take 5 g of polylactic acid (PLA, molecular weight 50000) and 5 g of polycaprolactone (PCL, molecular weight 40000), add 0.5 g of nano-montmorillonite (particle size 50 nm), and dissolve in 100 mL of DMF, and stir well to obtain a uniform inner layer spinning solution.

[0049] (2) Coaxial electrospinning preparation: The core material solution, inner layer spinning solution and outer layer spinning solution are respectively filled into the inner core, middle core and outer core syringes of the coaxial spinning machine, and the spinning parameters are set, voltage (outer layer 15 kV, inner layer 12 kV, inner 10 kV); push speed (outer layer 0.8 mL / h, inner layer 0.5 mL / h, inner core 0.3 mL / h), receiving distance is 15 cm, receiving roller speed is 50 r / min; the environmental temperature is 25°C, and the environmental humidity is 40%-50%.

[0050] After spinning, the collected microcapsules were dried in a vacuum drying oven at 60°C for 8h (to remove residual DMF), to obtain polyaspartic acid microcapsules with gradient wall thickness (outer layer wall thickness 100nm±10nm, inner layer wall thickness 500nm±20nm, particle size 5pm±0.5pm).

[0051] The preparation process of polysiloxane microcapsules is basically the same as that of polyaspartic acid microcapsules, except that the core material preparation is different, as follows:

[0052] Take 2.5g of polysiloxane, add 22.5mL of ethyl acetate, and add 0.12g of Span-60. After stirring thoroughly, polysiloxane core material solution is obtained.

[0053] The remaining properties (particle size, gradient wall thickness) are completely consistent with those of polyaspartic acid microcapsules.

[0054] The preparation method of UPy-PEG composite crosslinking agent is as follows:

[0055] (1) Put 40.0 g of PEG (molecular weight 2000) into a 500 mL round-bottom flask, and dry at 80°C under vacuum for 2h (vacuum degree -0.095 MPa) to obtain pretreated PEG; add 10.0 g of UPy to 100 mL of anhydrous toluene, stir thoroughly, and then filter through a 0.22 pm organic phase filter membrane to obtain a UPy-toluene solution;

[0056] (2) Add all the pretreated PEG to the UPy-toluene solution, stir evenly, and then replace the air in the flask with nitrogen gas (flow rate 50 mL / min); then add 0.1 g of stannous octoate, heat to 90°C, and reflux under nitrogen protection for 6h; during the reaction, monitor by thin layer chromatography (TLC, developing agent: dichloromethane / methanol = 9:1, by volume): when the characteristic spot of UPy (Rf=0.6) is significantly weakened and a new graft product spot (Rf=0.3~0.4) appears, it is considered as the end of the reaction. After the reaction is completed, the reaction liquid is cooled to room temperature, slowly poured into 500 mL of anhydrous ether, stirred vigorously for 30 min, and then collected by suction filtration. The precipitate is washed with anhydrous ether to remove residual ether and unreacted raw materials; the precipitate is dried in a vacuum drying oven at 60°C for 4h (vacuum degree -0.098 MPa) to remove residual solvents, and UPy-PEG composite crosslinking agent (stannous octoate residual amount ≤0.05wt%) is obtained.

[0057] S3. Protective layer composite: by mass ratio, medical grade TPE-ST substrate (Shore hardness 65A) 91.5%, nano-silica whisker grafted with KH-560 6.0%, nano-zinc oxide (particle size 50 nm) 1.0%, polytetrafluoroethylene powder (particle size 1.5 μm) 0.5%; 185℃ melt extrusion coated on the outer surface of the support layer; after segmented cooling (front segment 60℃, rear segment 28℃, to avoid internal stress), traction shaping (speed 10m / min, to ensure uniform pipe diameter), a protective layer with a thickness of 0.2mm is obtained; finally, ethylene oxide sterilization (dose 700mg / L, temperature 55℃, time 3h, sterility level SAL≥10 -6 ), a medical infusion tube finished product (total inner diameter 2.5mm, total wall thickness 0.7mm) is obtained.

[0058] The preparation method of the nano-silica whisker grafted with KH-560 is as follows:

[0059] Take 10g of nano-silica whisker (particle size 0.08μm, industrial grade) and add 50mL of anhydrous ethanol, ultrasonic cleaning for 20min, 80℃ vacuum drying for 2h, to obtain pretreated nano-silica whisker; take 1.5g of KH-560 silane coupling agent, dissolve in 30mL of mixed solvent (anhydrous ethanol: deionized water = 9:1, by volume), add 1mol / L hydrochloric acid dropwise to adjust pH=4~5, stir at room temperature for 30min, to obtain KH-560 hydrolyzate;

[0060] Add all the prepared pretreated nano-silica whisker to the KH-560 hydrolyzate, stir at 70℃ constant temperature water bath for 4h; after the reaction is completed, collect the solid by suction filtration, wash with anhydrous ethanol, vacuum dry at 100℃ for 4h, grind through a 200 mesh sieve, to obtain nano-silica whisker grafted with KH-560.

[0061] Example 2: Preparation of horticultural drip irrigation pipe, used in horticultural scenes.

[0062] Compared with Example 1, the following adjustments are made (where not mentioned, it is considered the same as Example 1):

[0063] In S1, the flow channel layer wall thickness is 0.25mm, and the flow channel layer inner diameter is 5mm;

[0064] In S2, the polyaspartic acid microcapsule addition amount is 1.0wt%; there are 5 stainless steel wires with a diameter of 0.10mm, the stainless steel wire winding pitch is 18mm, and the support layer wall thickness is 0.4mm;

[0065] In S3, the nano-zinc oxide addition amount is 1.2wt%, the traction speed is 8m / min, no sterilization is needed, and the protective layer wall thickness is 0.35mm.

[0066] The remaining components, parameters, and preparation steps are the same as those in Example 1.

[0067] Example 3: Preparation of disinfection water pipe for disinfection scene.

[0068] Compared with Example 1, the following adjustments are made (where not mentioned, it is the same as Example 1):

[0069] In S1, the flow channel layer has a wall thickness of 0.22 mm and an inner diameter of 4 mm; the carboxyl-modified Ag-TiO2 is added at a dosage of 1.0 wt%;

[0070] In S2, four stainless steel wires with a diameter of 0.09 mm are used, and 0.3 wt% of ionic liquid (1-butyl-3-methylimidazolium tetrafluoroborate, whose imidazole cation can adsorb Cl - in the disinfection water to prevent Cl - from penetrating to the surface of the stainless steel wire to accelerate corrosion and improve the corrosion resistance of the pipe in a chlorine-containing disinfection water environment) is added to the TPU matrix;

[0071] In S3, the nano-silica whisker is added at a dosage of 8 wt%, and the protective layer has a wall thickness of 0.3 mm.

[0072] The remaining components, parameters, and preparation steps are the same as in Example 1.

[0073] Example 4

[0074] Compared with Example 1, the 316L stainless steel wire is treated as follows:

[0075] The 316L stainless steel wire used in Example 1 is immersed in a 2 g / L dopamine hydrochloride solution (pH = 8.5, medical grade) at 30°C for 2 h; after being taken out and dried, it is immersed in a 1 g / L tannic acid-zinc phytate composite solution (mass ratio, tannic acid: zinc phytate = 1:2, medical grade) at 25°C for 1 h, and dried to obtain a composite coating with a thickness of 0.04 mm; the coating is immersed in a PCL monomer solution (PCL concentration 5 wt%, solvent chloroform, medical grade) with 0.1 wt% azobisisobutyronitrile, and polymerized at 60°C for 4 h to graft PCL shape memory polymer brushes;

[0076] The remaining components, parameters, and preparation steps are the same as in Example 1.

[0077] Example 5

[0078] Compared with Example 4, the following modifications are made:

[0079] The flow channel layer coupling agent is replaced with an equal amount of poly-N-isopropyl acrylamide (PNIPAM)-adipic dihydrazide composite coupling agent.

[0080] The preparation method of the composite coupling agent: take PNIPAM (molecular weight 5000) 2 g and adipic dihydrazide 3 g, dissolve in 50 mL DMF, stir at 70°C for 6 h, remove the solvent by distillation under reduced pressure, and get the composite coupling agent.

[0081] Stainless steel wire coating: add 0.3wt% carbon quantum dots (particle size 5nm, medical grade) in PCL polymer brush;

[0082] TPU matrix: add 0.5wt% polyethylene glycol monomethyl ether (mPEG, molecular weight 2000);

[0083] The remaining components, parameters and preparation steps are the same as example 4.

[0084] Comparative example 1

[0085] Compared with example 1, step S2 replaces the gradient wall thickness microcapsule with a single wall thickness microcapsule, the wall material is polylactic acid-poly (ε-caprolactone), the wall thickness is 300 nm, and there is no nanometer montmorillonite.

[0086] The remaining components, parameters and preparation steps are the same as example 1.

[0087] Comparative example 2

[0088] Compared with example 1, step S2 changes the stainless steel wire to single spiral winding (pitch 18mm), and cancels the wave-shaped preforming.

[0089] The remaining components, parameters and preparation steps are the same as example 1.

[0090] Comparative example 3

[0091] Compared with example 1, step S2 removes UPy-PEG composite crosslinking agent.

[0092] The remaining components, parameters and preparation steps are the same as example 1.

[0093] Comparative example 4

[0094] Compared with example 1, step S1 cancels the ammonia plasma etching treatment, and only the PU substrate is mixed and extruded with the functional components.

[0095] The remaining components, parameters and preparation steps are the same as example 1.

[0096] Comparative example 5

[0097] Compared with example 3, step S1 removes the surface carboxyl modified Ag-TiO2 in the flow channel layer, and the PU substrate accounts for 97.5%.

[0098] The remaining components, parameters and preparation steps are the same as example 1.

[0099] Experimental example

[0100] The pipes prepared in Examples 1-5 and Comparative Examples 1-5 were subjected to performance tests, and the test results are shown in Table 1. The specific test performances and test methods are as follows:

[0101] (1) Anti-collapsing performance test (all scenarios, including medical, horticultural, and disinfection scenarios).

[0102] Test method: Take each pipe sample (length 30 cm), and repeatedly bend it with a radius of 5 cm using a bending instrument (rate 30 times / min). After 500 bending tests, measure the retention rate of the lumen cross-sectional area (measured by a laser diameter measuring instrument). Record the number of bending tests at which the lumen collapses for the first time (retention rate <80%).

[0103] (2) Drug / medium residual rate test (all scenarios).

[0104] Test method: For medical scenarios, use parenteral nutrition preparations (high viscosity) and physiological saline (low viscosity). For horticultural scenarios, use high-concentration water and fertilizer. For disinfection scenarios, use a 2% sodium hypochlorite solution. After 30 min of circulation, dry the pipes and weigh the residual medium. Calculate the residual rate (residual rate = residual mass / total mass of delivery x 100%).

[0105] (3) Antibacterial performance test (only medical / disinfection scenarios).

[0106] Test method: Inject E. coli (ATCC 25922) and S. aureus (ATCC 29213) bacterial suspensions (106CFU / mL) into the pipes, and incubate them at 37°C for 24 h. Dilute and plate count, and calculate the inhibition rate

inhibition rate = (blank group bacterial colony count - sample group bacterial colony count) / blank group bacterial colony count x 100%

[0107] (4) Corrosion resistance test (all scenarios)

[0108] Take a pipe sample (length 20 mm, weigh m0). For medical scenarios, soak the sample in vitamin C injection (pH=3.5) and sodium bicarbonate injection (pH=8.5). For horticultural scenarios, soak the sample in salt water and fertilizer (NaCl concentration 2%). For disinfection scenarios, soak the sample in a 2% sodium hypochlorite solution. After 30 days, observe the appearance of the pipe for swelling, and calculate the swelling rate.

[0109] Swelling rate: After 30 days, remove the sample, absorb the surface medium with filter paper, and immediately weigh it as m1. Calculate the swelling rate (swelling rate = (m1- m0) / m0 x 100%).

[0110] Stainless steel wire corrosion rate: First, the pipeline sample is repeatedly bent 500 times with a radius of 5 cm by a bending instrument (to simulate actual wear scenarios such as repeated body position adjustment in clinical practice and production line dragging), then the sample is immersed in the corresponding corrosion medium (medical scene: vitamin C injection; disinfection scene: 2% sodium hypochlorite), after 30 days, the stainless steel wire is taken out, washed with absolute ethanol, vacuum dried at 80°C for 2h, the mass before and after corrosion is measured, and the corrosion rate is calculated (corrosion rate = (mass before corrosion - mass after corrosion) / mass before corrosion x 100%).

[0111] (5) Warm shaping retention rate test (only medical scene).

[0112] Test method: The sample is first refrigerated at 2-8°C for 24h, bent into an arc with a radius of 5cm, and after recovery to 37°C (body temperature), the arc retention rate after 12h is measured; then placed in a 50°C constant temperature box for 8h, and the shaping retention rate is tested (retention rate = actual bending radius / target bending radius x 100%).

[0113] (6) Interlayer peeling strength test (all scenes).

[0114] Test method: The pipeline is cut along the axial direction to prepare a 15mm wide peeling sample, and the interlayer peeling strength is tested by a tensile testing machine (unit: N / mm), and the average value of 5 tests is taken.

[0115] Table 1:

[0116]

[0117]

[0118] It is worth noting that:

[0119] ① In Table 1, "-" means that the relevant test has not been performed;

[0120] ② Comparative Examples 2 and 3 belong to the medical scene, but the performance of residual rate, warm shaping retention rate, etc. is not tested, the core reason is that the key performance (anti-collapse, interlayer bonding) has been seriously out of standard, and subsequent testing has lost practical application significance.

[0121] ③ Due to the space limitation of the layout of Table 1, the units of each index are not marked, now it is uniformly explained: all "rate" indexes (including lumen retention rate, parenteral nutrition residual rate, saline residual rate, water and fertilizer residual rate, sodium hypochlorite residual rate, Escherichia coli inhibition rate, Staphylococcus aureus inhibition rate, swelling rate, metal corrosion rate, 2-37°C warm shaping retention rate, 50°C warm shaping retention rate) are in %; "first collapse bending times" is a count index, the unit is "times"; the interlayer peeling strength unit is "N / mm".

[0122] From Table 1, it can be seen that Examples 1-3 are respectively adapted to medical, horticulture, and disinfection scenarios, effectively improving the core problems of the flexible delivery pipeline in the background art, such as easy collapse, insufficient versatility, and poor transmission stability, and overall performance is good. Specifically, the lumen retention rate of the three after 500 bends is all ≥91%, and the interlayer peeling strength is all ≥2.2 N / mm, alleviating the phenomenon of traditional pipeline collapse and easy peeling between layers; the medium residue rate under different scenarios is all ≤0.79%, and the antibacterial rate in medical / disinfection scenarios is all ≥94%, reducing the risk of medium residue and bacterial breeding, and adapting to multiple transmission requirements; there is no obvious swelling in the corrosion resistance test, and the corrosion rate of the stainless steel wire is all ≤0.03%, improving the use stability of the pipeline in different corrosion environments.

[0123] Example 4 further reduces the corrosion rate of the stainless steel wire and improves the lumen retention rate and interlayer peeling strength by coating and grafting PCL shape memory polymer brushes on the stainless steel wire based on Example 1; Example 5 optimizes the warm-shaping retention rate by replacing the composite coupling agent, adding carbon quantum dots and mPEG based on Example 4, making the pipeline more adaptable in the warm environment of the medical scenario.

[0124] In Comparative Example 1, due to the use of a single wall thickness microcapsule and the absence of nanometer montmorillonite, the functional component cannot be released according to the viscosity of the medium, resulting in a significant increase in medium residue rate, and the lumen retention rate and interlayer peeling strength are also affected, making it difficult to meet the adaptive needs of multiple medium transmission. In Comparative Example 2, the stainless steel wire is replaced with a single spiral winding and the wave-shaped pre-forming is removed, lacking a three-dimensional support network to disperse bending stress, resulting in a low lumen retention rate and a significant reduction in the number of first collapse bends, making it prone to collapse and liquid blockage, and unable to adapt to scenarios requiring frequent bending. In Comparative Example 3, the UPy-PEG composite crosslinking agent is removed, and the TPU matrix lacks dynamic crosslinking properties, resulting in insufficient interlayer bonding force and decreased resistance to collapse, making it difficult to balance pipeline flexibility and structural stability, limiting the adaptation scenarios. In Comparative Example 4, the ammonia plasma etching process is removed, and the flow channel layer lacks the mechanical interlocking action of the nano-pits, resulting in a significant decrease in interlayer peeling strength and an increase in medium residue rate. In Comparative Example 5, the antibacterial performance is significantly reduced due to the absence of surface carboxyl-modified Ag-TiO2, and the corrosion resistance of Ag-TiO2 is also lacking, resulting in a significant increase in swelling rate and corrosion rate of the stainless steel wire in the disinfection scenario, making it difficult to adapt to the hygiene and corrosion resistance requirements of food processing disinfection water delivery.

Claims

1. A freely shaped liquid conveying pipe, comprising, from the inside out, a flow channel layer, a metal-elastomer support layer, and a wear-resistant protective layer; characterized in that: The flow channel layer is composed of a polyether-type polyurethane substrate, transparent nematic liquid crystal microspheres with carboxyl groups modified on the surface, silver-doped nano-titanium dioxide with carboxyl groups modified on the surface, and adipic acid dihydrazide coupling agent. The inner surface of the polyether-type polyurethane substrate is etched with ammonia plasma to form shallow dish-shaped nano-pits. The metal-elastomer support layer comprises multiple double-helix corrugated stainless steel wires and a thermoplastic polyurethane matrix; The stainless steel wire is spirally wound at equal angles; The thermoplastic polyurethane matrix is ​​cross-linked by a ureidopyrimidinone-polyethylene glycol composite cross-linking agent and dispersed with two types of microcapsules with polyaspartic acid as the core material and polysiloxane as the core material. The wall materials of both microcapsules have a gradient wall thickness structure. The outer layer is polyethylene glycol-polyurea-formaldehyde with a wall thickness of 80nm~120nm. The inner layer is polylactic acid-polycaprolactone with the addition of 0.3wt%~0.7wt% nano-montmorillonite and an inner layer wall thickness of 400nm~600nm. The wear-resistant protective layer is composed of thermoplastic TPE-ST substrate, nano zinc oxide, polytetrafluoroethylene micro powder, and nano silica whiskers with KH-560 silane coupling agent grafted on the surface.

2. The shapeable liquid delivery conduit of claim 1, wherein, The thickness of the flow channel layer is 0.1 mm to 0.3 mm, wherein the amount of surface carboxyl-modified liquid crystal microspheres added is 1.5 to 2.5 wt%; the amount of surface carboxyl-modified silver-doped nano-titanium dioxide added is 0.6 to 1.0 wt%; the amount of adipic acid dihydrazide coupling agent added is 0.3 to 0.7 wt%; and the diameter of the nano-pit opening is 0.5 μm to 1.0 μm and the depth is 0.2 μm to 0.4 μm.

3. The shapeable liquid delivery conduit of claim 1, wherein, The metal-elastic support layer has a thickness of 0.2~0.5mm, and contains 3~5 stainless steel wires with a diameter of 0.05~0.10mm.

4. The shapeable liquid delivery conduit of claim 1, wherein, In the thermoplastic polyurethane matrix, the amount of ureidopyrimidinone-polyethylene glycol composite crosslinking agent added is 2~4wt%; the amount of both types of microcapsules added is 0.4wt%~1.2wt%, and the particle size is 1μm~10μm.

5. The shapeable liquid delivery conduit of claim 1, wherein, The wear-resistant protective layer has a thickness of 0.1 mm to 0.35 mm, wherein the amount of nano-silica whiskers added is 4 wt% to 8 wt%, and the particle size is 0.04 μm to 0.12 μm; the amount of nano-zinc oxide added is 0.8 wt% to 1.2 wt%, and the particle size is 30 nm to 80 nm; and the amount of polytetrafluoroethylene micro powder added is 0.3 wt% to 0.7 wt%, and the particle size is 0.8 μm to 2.5 μm.

6. The shape-able liquid delivery conduit of claim 1, wherein, The stainless steel wire is coated with a 0.03mm~0.06mm dopamine-tannic acid-zinc phytate composite coating, and the coating is grafted with polycaprolactone shape memory polymer brush.

7. The freely malleable liquid conveying pipeline according to claim 6, characterized in that, The adipic acid dihydrazide coupling agent in the flow channel layer was replaced with a poly(N-isopropylacrylamide-adipic acid dihydrazide) composite coupling agent. 0.2wt%~0.4wt% carbon quantum dots were added to the polycaprolactone shape memory polymer brush with stainless steel wire coating, and 0.3wt%~0.7wt% polyethylene glycol monomethyl ether was added to the thermoplastic polyurethane matrix.

8. A method for forming a freely malleable liquid conveying pipe as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Carboxyl modification of the surface of silver-doped nano-titanium dioxide and transparent nematic liquid crystal microspheres is performed, and then mixed with polyether polyurethane substrate and adipate dihydrazide coupling agent. The mixture is melt-extruded at 160℃~200℃, and shallow dish-shaped nano-pits are formed by etching the inner surface of the extruded substrate using an ammonia plasma etching device to obtain the flow channel layer. S2. The stainless steel wire is pre-formed into a double helical wave shape, with the pitch wound around the outer surface of the flow channel layer. At the same time, the thermoplastic polyurethane matrix, ureidopyrimidinone-polyethylene glycol composite crosslinking agent, and two microcapsules are mixed and melt-compositely extruded at 180℃~210℃ to cover the outside of the stainless steel wire and form a support layer. S3. Mix TPE-ST substrate, nano zinc oxide, polytetrafluoroethylene micro powder, and KH-560 grafted nano silica whiskers, melt-extrude at 170℃~205℃, coat the outer surface of the support layer, and obtain the finished product after cooling and traction shaping.

9. The molding method according to claim 8, characterized in that, In step S1, the ammonia plasma etching power is 300W~500W and the etching time is 40s~80s; in step S3, segmented cooling is adopted, and the cooling parameters are: 55℃~65℃ for the front section and 25℃~30℃ for the rear section.

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