CN114479451B - Composite pipe and preparation method thereof - Google Patents

Abstract

The invention relates to a composite pipe and a preparation method thereof, wherein the preparation method of the composite pipe comprises the following steps: obtaining a coating liquid, wherein the coating liquid comprises polyimide precursor, polytetrafluoroethylene, graphite and carbon black; coating the core wire at least once by using the coating liquid, and imidizing the coating liquid on the core wire after each coating; and (5) core pulling to prepare the composite pipe. The composite pipe has higher mechanical property and lower friction coefficient.

Description

Composite pipe and preparation method thereof

Technical Field

The invention relates to the technical field of medical materials, in particular to a composite pipe and a preparation method thereof.

Background

Polyimide (PI) is a high molecular polymer containing a cyclic imide group in the molecular chain, and PI can be classified into a benzene-like PI, a soluble PI, a polyamide, an imide (PAI), and a polyether imide (PEI). PI has the advantages of excellent high temperature resistance, low temperature resistance, high strength and modulus, high creep resistance, high dimensional stability, low thermal expansion coefficient, high electrical insulation, low dielectric constant, low loss, radiation resistance, corrosion resistance, biocompatibility and the like, and simultaneously has the characteristics of space materials such as low vacuum volatile matters, less volatile congealable matters and the like, and can be processed into polyimide films, high temperature resistant engineering plastics, matrix resins for composite materials, high temperature resistant adhesives, fibers, foam and the like, so that the PI has wide application prospect and huge commercial value in a plurality of high and new technical fields, and is called as a "hands for solving problems". Polyimide material is gradually applied to the biomedical field at present, polyimide is processed into polyimide precision tubing, and the polyimide precision tubing is used as a catheter for minimally invasive interventional therapy and is used for auxiliary therapy.

However, some special medical polyimide tubing has high precision requirements, such as thin wall, small tolerance, radial opacity, low friction, development effect and the like, particularly low friction, so as to avoid 'adhesion' and be visible under perspective, reduce friction resistance in the drug or appliance pushing process and friction damage to blood vessels in the introducing process, and have important effects on assisting doctors in treatment.

Disclosure of Invention

Based on the above, it is necessary to provide a composite pipe having higher mechanical properties and a lower friction coefficient and a method for preparing the same.

The preparation method of the composite pipe comprises the following steps:

obtaining a coating liquid; the coating liquid comprises polyimide precursor, polytetrafluoroethylene, graphite and carbon black;

coating the core wire at least once by using the coating liquid, and imidizing the coating liquid on the core wire after each coating;

And (5) core pulling to obtain the composite pipe.

In one embodiment, in the coating liquid, the mass ratio of the graphite to the polytetrafluoroethylene is 0.5-1; the mass ratio of the carbon black to the polytetrafluoroethylene is 0.2-0.8.

In one embodiment, the polytetrafluoroethylene is polytetrafluoroethylene particles with the particle size of 1-20 μm; and/or

The particle size of the graphite is 1000-2000 meshes; and/or

The particle size of the carbon black is 1000-2000 meshes.

In one embodiment, the polyimide precursor is contained in the coating liquid at a mass percentage concentration of 50 to 70%.

In one embodiment, the polytetrafluoroethylene is 5-15% by weight and/or the carbon black is 2-5% by weight in the coating solution

In one embodiment, the coating liquid further comprises a developer, wherein the mass percentage concentration of the developer is 5% -10%.

In one embodiment, the developer is selected from: one or more of barium sulfate, iodine preparation, tungsten powder and bismuth oxychloride.

In one embodiment, the core wire is a stainless steel wire, a silver-plated copper wire, or a pure copper wire.

In one embodiment, the imidization process includes the steps of:

Sintering the coating liquid on the core wire in a sintering furnace, setting the sintering furnace to five-stage temperature and raising the temperature from low to high stage by stage, wherein the five-stage temperature ranges from 110 ℃ to 150 ℃, 190 ℃ to 240 ℃, 270 ℃ to 300 ℃, 300 ℃ to 350 ℃ and 350 ℃ to 420 ℃ respectively.

A composite pipe comprising the following components: polyimide precursor, polytetrafluoroethylene, graphite and carbon black.

The invention has the following beneficial effects:

According to the preparation method of the composite pipe, the coating liquid containing the polyimide precursor, the polytetrafluoroethylene, the graphite and the carbon black is adopted, the polytetrafluoroethylene permeates into polyimide molecular chains in the imidization process of the polyimide precursor, and meanwhile, the graphite and the carbon black are embedded into a reticular chain to form a reticular film with a specific space structure, so that on one hand, the lubricity of a coating layer can be improved, further, the friction resistance in the pushing process of a medicine or an appliance is reduced, and the friction damage to a blood vessel in the blood vessel leading-in process is avoided; on the other hand, the components such as graphite, carbon black and the like have higher toughness, so that the strength and the lubricity can be improved, and the components are dispersed in the film to facilitate stress dispersion, improve the mechanical property of the composite polyimide material and facilitate the smooth core pulling of the polyimide material.

In addition, the preparation method is simple to operate, the production cost can be reduced, the raw materials are cheap and easy to obtain, other additives are not required to be added, the damage to the human body can be reduced, and meanwhile, the requirement of biocompatibility is met, so that the preparation method is particularly suitable for the field of interventional medical treatment.

Detailed Description

The present invention will be described more fully hereinafter in order to facilitate an understanding of the present invention, and preferred embodiments of the present invention are set forth. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.

Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.

An embodiment of the invention provides a preparation method of a composite pipe, which comprises the following steps:

s101: obtaining a coating liquid, wherein the coating liquid comprises polyimide precursor, polytetrafluoroethylene, graphite and carbon black;

In step S101, the step of obtaining the coating liquid includes: the polyimide precursor solution, polytetrafluoroethylene, graphite and carbon black are mixed to prepare a desired coating solution. Specifically, mechanical stirring, ultrasonic, etc. methods may be employed to improve the uniformity of the coating liquid.

In some embodiments, the coating solution comprises 50-70% polyimide precursor by mass, 5-15% polytetrafluoroethylene by mass, 5-10% graphite by mass, and 2-5% carbon black by mass;

It should be noted that, in the present invention, the term "coating liquid" is understood to mean that, as one of the raw materials for forming the composite pipe, the action of "coating" is not to be understood as limiting the product "coating liquid", and specifically, the desired pipe may be obtained by using the existing method, for example: coating, dipping, spraying, etc.

The polyimide precursor is a polyamic acid solution, which can be prepared by a conventional method, and is not particularly limited herein, and is understood to be within the scope of the present invention. The precursor is further a prepolymer solution obtained by reacting aromatic dianhydride and aromatic diamine, wherein the molar ratio of the aromatic dianhydride to the aromatic diamine can be 1:0.5-1:1. The polyimide precursor may be prepared by reacting a plurality of monomers, and the reactants of the polyimide precursor include at least one aromatic dianhydride and at least one aromatic diamine. The aromatic dianhydride may be selected from: 3,4 '-diphenyl ether tetracarboxylic dianhydride, 3,4' -benzophenone tetracarboxylic dianhydride, 3,4',4' -biphenyltetracarboxylic dianhydride, and pyromellitic dianhydride. The aromatic diamine may be selected from: one or more of 4,4' -diaminodiphenyl ether, 4' -diaminodiphenyl methane, di (3-aminophenoxy) benzophenone, p-phenylenediamine, m-phenylenediamine, and 4,4' -diaminodiphenyl sulfone.

The solvent in the prepolymer solution may be a polar solvent, which may be selected from the group consisting of: one or more of N, N-dimethylacetamide, trifluoroacetic acid, dimethylsulfoxide, acetonitrile, dimethylformamide, hexamethylphosphoramide, methanol, ethanol, isopropanol, pyridine, acetone, N-butanol, and aniline;

In one embodiment, the aromatic dianhydride is 3,4' -diphenyl ether tetracarboxylic dianhydride and the aromatic diamine is diaminodiphenyl ether; the molar ratio of the diaminodiphenyl ether to the 3,4' -diphenyl ether tetracarboxylic dianhydride is 0.8-1.2; preferably, the molar ratio of 3,4' -diphenylether tetracarboxylic dianhydride to diaminodiphenyl ether is 1:1.

The mass percentage concentration of the prepolymer solution is 5-30%; further, the mass percentage concentration of the prepolymer solution is 10% -25%; further, the mass percentage concentration of the prepolymer solution is 12% -23%; further, the concentration of the prepolymer solution was 20% by mass. The viscosity of the prepolymer solution may be 10 Pa-s to 100 Pa-s; further, the viscosity of the prepolymer solution is 20 Pa.s to 80 Pa.s; further, the viscosity of the prepolymer solution is 30 Pa.s to 60 Pa.s; further, the viscosity of the prepolymer solution was 50 Pa.s.

It is understood that the prepolymer solution in the invention refers to a solution containing a prepolymer product and a solvent, and can be used as the prepolymer solution directly after raw material reaction, or can be prepared into a solution with corresponding concentration and viscosity by separating the prepolymer product and adding the solvent, and the solution is understood to be within the protection scope of the invention.

Polytetrafluoroethylene (PTFE), which may be a commercially available starting material, such as: MP1100, MP1300, MP1600, MP1400F, etc., are not particularly limited herein. Preferably, the polytetrafluoroethylene is polytetrafluoroethylene particles having a particle size of 1 μm to 20 μm. The polytetrafluoroethylene has better lubricity, the friction coefficient of the contrast material can be further reduced under the coordination of graphite and carbon black, the polytetrafluoroethylene has chemical inertness, toxic substances are not easy to generate, and the polytetrafluoroethylene is suitable for the field of interventional medical instruments.

Both graphite and carbon black can be commercially available materials. The particle size of the graphite may be 1000 to 2000 mesh and the particle size of the carbon black may be 1000 to 2000 mesh. The composite polyimide pipe can be improved in comprehensive performance by adding graphite and carbon black, friction coefficient is reduced, mechanical property of the material is improved, and core pulling in the pipe preparation process is facilitated.

The mass ratio of the graphite to the polytetrafluoroethylene is 0.5-1; further, the mass ratio of graphite to polytetrafluoroethylene is 0.8-1; further, the mass ratio of graphite to polytetrafluoroethylene was 1. The mass ratio of the carbon black to the polytetrafluoroethylene is 0.2-0.8; further, the mass ratio of the carbon black to the polytetrafluoroethylene is 0.4-0.6; further, the mass ratio of carbon black to polytetrafluoroethylene was 0.5.

The coating liquid can also comprise a developer, and the medical tube with good developing effect can be formed by directly adding the developer into the tube, so that an additional processing developing ring in the subsequent use process is not needed, and the operation complexity is reduced.

In the coating liquid, the mass percentage concentration of the developer is 5-10%. The developer may be any existing developer and is understood to be within the scope of the present invention. The developer may be selected from: one or more of barium sulfate, iodine preparation, tungsten powder and bismuth oxychloride. In an embodiment, the developer is a mixture of tungsten powder and bismuth oxychloride, and the mass percentage of the tungsten powder and the bismuth oxychloride can be 1:0.5-1:9. In another embodiment, the developer is barium sulfate, and the barium sulfate has certain lubricity, so that development can be realized, the friction coefficient of the pipe can be reduced to a certain extent, and the mechanical property of the pipe is improved.

The core wire can be stainless steel wire, silver-plated copper wire or pure copper wire, and preferably the core wire is pure copper wire. Because different acting forces are arranged between the core wires of different materials and the coating layer, after the coating layer is formed on the outer surface of the core wire, the pure copper wire is adopted as the core wire, so that the core pulling is more facilitated, and the damage to the coating layer in the core pulling process can be effectively reduced.

S102: pretreating the core wire;

It will be appreciated that when the core wire does not need to be pretreated, the step S102 may be omitted, and the subsequent step is directly performed, preferably, the step S102 is performed before the subsequent step is performed, so as to remove impurities on the surface of the core wire, which is beneficial to the performance of the subsequent step.

Further, the pretreatment of the core wire is performed as follows: washing the core wire with ethanol and water in sequence and drying; the core wire can be paid off by adopting a paying-off device, sequentially passes through a washing tank containing ethanol and water at a preset speed, washes the surface of the core wire, and then dries. Wherein, 50% -80% ethanol is preferably used for washing; more preferably with 75% ethanol;

the number and order of the ethanol and water washes are not particularly limited, and examples include: it is understood that it is within the scope of the present invention to wash with ethanol once, then with water twice, or with ethanol and water alternately. In addition, the ultrasonic method can be adopted to assist in cleaning in the cleaning process, so that the cleaning effect is improved.

In addition, the two ends of the core wire can be respectively arranged on a paying-off reel and a winding reel, and certain tension can be applied to the released core wire through the paying-off reel and the winding reel, so that the released core wire is in a tightening state, the cleaning effect is improved, and the operation of the subsequent steps is facilitated. In addition, the paying-off rate of the paying-off reel can be controlled by the winding-up reel to control the moving speed of the core wire in the first cleaning tank and the second cleaning tank and the moving speed of the core wire in the coating liquid in the subsequent steps. In one embodiment, the rate of movement of the wick during the cleaning process is between 0.2m/min and 10m/min.

S103: coating the core wire at least once by using the coating liquid, and imidizing the coating liquid on the core wire after each coating;

Further, step S103 further includes a step of preparing a coating liquid:

the thickness of the coating layer can be adjusted by adjusting the concentration of the coating liquid, when the coating liquid needs to be diluted, a solvent can be added for dilution, the solvent needs to be uniformly mixed with other components in the coating liquid and volatilized in the imidization treatment process, and the solvent can be the same as or different from the original solvent in the coating liquid.

In step S103, the coating liquid may be applied to the surface of the core wire by dipping. Further, the coating in step S103 is a diameter control coating. Specifically, the core wire coated with the coating liquid can be passed through the die cavity to control the amount of liquid carried on the core wire and thus the thickness of the coating layer. In one embodiment, the thickness of the coating layer is 20 μm to 100 μm. In one embodiment, the total thickness of the coating layer is 30 μm to 80 μm; . In one embodiment, the total thickness of the coating layer is 40 μm to 60 μm. It will be appreciated that a take-up and pay-off device may also be used to pass the core wire at a certain velocity through the dip tank containing the coating liquid. In one embodiment, the rate of movement of the core wire during the coating process is between 0.2m/min and 10m/min. It should be noted that the moving speeds of the core wires during the cleaning and coating processes may be the same or different, and should not be construed as limiting the present invention.

The imidization treatment in step S103 refers to a process of imidizing and curing the polyimide precursor to obtain a crosslinked polyimide film.

Further, in step S103, the core wire coated with the coating liquid is subjected to imidization treatment at least three treatment temperatures sequentially increasing in temperature, and the minimum treatment temperature is not lower than 100 ℃, and at least one treatment temperature is 300 ℃ or higher. Further, the temperature difference between adjacent two process temperatures is less than or equal to 80 ℃. Further, in step S103, a difference between at least two adjacent processing temperatures is less than or equal to 30 ℃. Further, the temperature is less than or equal to 20 ℃ so as to improve the imidization treatment effect and solve the problem of poor interface bonding.

Further, in step S103, the difference between the adjacent processing temperatures becomes smaller and larger. Further, the core wire coated with the coating liquid is subjected to imidization treatment at N treatment temperatures in sequence, wherein the imidization treatment is performed at a first treatment temperature, an Mth treatment temperature, an Nth treatment temperature; m is an integer greater than or equal to 3, and N is an integer greater than or equal to 5; wherein ΔT1 is the difference between the Mth processing temperature and the Mth processing temperature, and ΔT2 is the difference between the Mth processing temperature and the Mth processing temperature; deltaT3 is the difference between the Nth processing temperature and the N-1 th processing temperature, deltaT4 is the difference between the N-1 th processing temperature and the N-2 th processing temperature; further, Δt2 is not less than Δt1; Δt3 is not less than Δt4.

Further, the processing temperatures include at least a first processing temperature, a second processing temperature, a third processing temperature, a fourth processing temperature, and a fifth processing temperature, wherein the first processing temperature is in a range of 110 ℃ to 150 ℃, the second processing temperature is in a range of 190 ℃ to 240 ℃, the third processing temperature is in a range of 270 ℃ to 300 ℃, the fourth processing temperature is in a range of 300 ℃ to 350 ℃, and the fifth processing temperature is in a range of 350 ℃ to 420 ℃.

Further, the processing temperatures include at least a first processing temperature, a second processing temperature, a third processing temperature, a fourth processing temperature, and a fifth processing temperature, wherein the first processing temperature is in a range of 115 ℃ to 130 ℃, the second processing temperature is in a range of 195 ℃ to 220 ℃, the third processing temperature is in a range of 275 ℃ to 285 ℃, the fourth processing temperature is in a range of 300 ℃ to 310 ℃, and the fifth processing temperature is in a range of 350 ℃ to 360 ℃.

Further, the first treatment temperature is 120 ℃, the second treatment temperature is 200 ℃, the third treatment temperature is 280 ℃, the fourth treatment temperature is 300 ℃, and the fifth treatment temperature is 350 ℃.

Further, in step S103, the imidization process includes the steps of:

The core wire coated with the coating liquid sequentially passes through the sintering furnace at a moving speed of 0.2m/min-10m/min, and the sintering furnace adopts sectional program control heating. Specifically, the sintering furnace is set to be at five-gear temperature and is gradually warmed from low to high, and the ranges of the five-gear temperature are respectively as follows: 110-150 ℃, 190-240 ℃, 270-300 ℃, 300-350 ℃ and 350-420 ℃. Further, the temperature ranges of the fifth gear are 120 ℃ to 150 ℃, 200 ℃ to 240 ℃, 280 ℃ to 300 ℃,300 ℃ to 350 ℃ and 350 ℃ to 420 ℃ respectively. Further, the five-gear temperatures are respectively: 120 ℃, 200 ℃, 280 ℃,300 ℃, 350 ℃.

By adopting the method, the imidization treatment effect can be improved, polytetrafluoroethylene is gradually heated and melted and permeated into polyimide molecular chains, and meanwhile, graphite and carbon black are concomitantly embedded into a reticular chain, so that the purpose of fusion between reinforcing materials is achieved, and a coating film with a better space structure is formed. On one hand, the problem of poor interface bonding between coating layers can be effectively solved, and on the other hand, the mechanical property of the material can be improved, so that the precise composite polyimide pipe with mechanical strength, torsion transmission toughness and lubricity can be obtained.

It should be noted that the process parameters of the respective layers may be the same or different during the preparation process, and should not be construed as limiting the present invention.

It is understood that when the number of the coating layers is more than 2, the thicknesses of the layers may be equal or different, and may be adjusted according to the practical situation of the pipe, for example, the coating layer near the core wire is thicker, so as to facilitate core pulling, etc., and should not be construed as limiting the present invention.

After a coating layer with the required thickness is formed, the performances of the outer diameter, the surface roughness and the like of the pipe can be comprehensively checked, the qualified pipe is rolled by the rolling device, and when the redundant core wire or the composite polyimide pipe is required to be cut, the cutting device can be used for cutting. Because the pipe is cut before the core is pulled, the damage to the pipe caused by the cutting process can be effectively avoided.

S104: and (5) core pulling to obtain the composite pipe.

The composite pipe can be obtained by adopting the existing method for core pulling.

The preparation method is characterized in that the preparation method adopts a continuous one-step molding method, so that the composite pipe with better mechanical property and lower friction coefficient can be obtained, the operation is simple and convenient, and the method is suitable for industrial production.

The invention also provides the composite pipe prepared by the preparation method.

The invention also provides a composite pipe, which comprises the following components: polyimide, polytetrafluoroethylene, graphite, and carbon black. In one embodiment, the composition of the composite tubing further comprises a developer.

The invention also provides a system for preparing a composite pipe, comprising: cleaning tank, dipping tank, sintering furnace. The cleaning tank is used for cleaning the core wire, the dipping tank is used for coating the surface of the core wire with the coating liquid, and the sintering furnace is used for drying and imidizing the core wire coated with the coating liquid to form a coating layer; the number of the washing tanks, the soaking tanks and the like is not particularly limited, and can be adjusted according to specific requirements, and in addition, the system can also comprise a paying-off reel, a winding-up reel, a driving device and the like so as to control the movement speed and the movement direction of the core wire; cutting means, surface detection means, etc. may also be included.

The invention will now be illustrated by way of specific examples.

The reagents of unspecified origin in the examples below were commercially available as raw materials, with the main reagent sources shown in Table 1 below:

TABLE 1

Name of the name	Species of type	Production enterprises	Model or name of product
				PTFE resin	Low molecular weight type micropowder and the like	Kemu (a kind of medical herb)	MP1100
Graphite	1000-2000 Mesh	Chinese medicine	99％
				Developer agent	BaSO 4, iodine preparation, tungsten powder and bismuth oxychloride	Chinese medicine	99％
Carbon black	1000-2000 Mesh	Chinese medicine	99％

Example 1

1. The preparation method of the coating liquid comprises the following steps:

(1) 31g of 3,4' -diphenyl ether tetracarboxylic dianhydride and 250mL of N-methylpyrrolidone (NMP) are added into a 500mL three-neck flask in an ice-water bath under the protection of nitrogen, 18.5g of diaminodiphenyl ether is added into a reaction system, and a viscous polyamic acid solution, namely polyimide precursor solution, is obtained after 8h of reaction.

(2) And (3) uniformly mixing the polyimide precursor solution prepared in the step (1), polytetrafluoroethylene, carbon black, graphite and a developer to prepare a coating solution. In this example, the developer was barium sulfate, the polyimide precursor was 70% by mass, the polytetrafluoroethylene was 10% by mass, the carbon black was 5% by mass, the graphite was 10% by mass, and the barium sulfate was 5% by mass.

2. The preparation method of the composite pipe comprises the following steps:

(1) The method comprises the steps of selecting a stainless steel wire as a core wire, paying off the core wire through a paying-off device, sequentially entering a first cleaning tank and a second cleaning tank at a speed of 1m/min for cleaning, wherein the first cleaning tank is filled with ethanol with a mass percent concentration of 75%, the second cleaning tank is filled with pure water, and after cleaning, the core wire is dried through a drying device to remove impurities and moisture on the surface of the core wire.

(2) The cleaned core wire enters a coating area for primary coating, and the coating liquid is contained in the dipping tank;

(3) Placing the core wire coated with the coating liquid in a sintering furnace for solvent volatilization, imidization and solidification, setting the sintering furnace to a five-stage temperature which is 120 ℃, 200 ℃, 280 ℃,300 ℃ and 350 ℃ respectively, and heating the sintering furnace from low to high stage to form a first coating layer;

(4) The polyimide pipe is subjected to secondary coating in a coating groove, and the steps (2) and (3) are repeated for a plurality of times, and the polyimide pipe with the wall thickness reaching the requirement is finally obtained by adjusting the specification of a die and the set coating layer number, wherein the total thickness of the coating layer is 50 microns in the embodiment;

(5) And comprehensively testing the performances of the outer diameter, surface concave-convex and the like of the pipe, and finally obtaining the composite pipe after the qualified pipe passes through a winding device to be finished and is finally subjected to core pulling, wherein the composite pipe is used as the composite pipe in the embodiment 1.

Example 2

Substantially the same as in example 1, except that the developer was tungsten powder.

Example 3

Substantially the same as in example 1, except that the developer was a mixture of tungsten powder (3%) and bismuth oxychloride (2%). In the coating liquid, the mass percentage of tungsten powder is 3 percent, and the mass percentage of bismuth oxychloride is 2 percent.

Example 4

Substantially the same as in example 1, except that the core wire was a pure copper wire.

Example 5

Substantially the same as in example 1, except that the coating liquid was composed of: polyimide precursors, polytetrafluoroethylene, carbon black, graphite and barium sulfate and solvents; wherein the polyimide precursor has a mass percentage concentration of 70%, polytetrafluoroethylene has a mass percentage concentration of 5%, carbon black has a mass percentage concentration of 10%, graphite has a mass percentage concentration of 10%, and barium sulfate has a mass percentage concentration of 5%.

Example 6

Substantially the same as in example 1, except that in step (3), the temperature of the sintering furnace was set to a constant temperature, and the temperature value was 300 ℃.

Example 7

Substantially the same as in example 1, except that in step (3), the sintering furnace was set to a five-stage temperature of 120 ℃, 150 ℃, 200 ℃, 250 ℃, 300 ℃ respectively, and the temperature was raised from low to high stage by stage.

Comparative example 1

Substantially the same as in example 1, except that graphite was not contained in the coating liquid. The coating liquid comprises the following components: polyimide precursor, polytetrafluoroethylene, carbon black, barium sulfate and solvent; wherein the polyimide precursor has a mass percentage concentration of 70%, polytetrafluoroethylene has a mass percentage concentration of 10%, carbon black has a mass percentage concentration of 10%, and barium sulfate has a mass percentage concentration of 10%.

Comparative example 2

Substantially the same as in example 1, except that carbon black was not contained in the coating liquid. The coating liquid comprises the following components: polyimide precursor, polytetrafluoroethylene, graphite and barium sulfate; wherein the polyimide precursor has a mass percent concentration of 70%, polytetrafluoroethylene has a mass percent concentration of 10%, graphite has a mass percent concentration of 10%, and barium sulfate has a mass percent concentration of 10%.

Performance verification test

The properties of the composite pipes of examples 1-7 and comparative examples 1 and 2 were examined, as shown in Table 2, wherein the test instruments for each item are as follows:

breaking force: instron3365 universal tester

Elongation at break: nstron3365 universal testing machine

Coefficient of friction: friction coefficient tester

Developing effect: x-ray detection imaging instrument

TABLE 2

	Breaking force/N	Elongation at break/%	Coefficient of friction	Development effect
					Example 1	40	132	0.08	Clear and clear
Example 2	46	126	0.1	Clear and clear
					Example 3	32	124	0.15	Clear and clear
Example 4	53	120	0.2	Clear and clear
					Example 5	43	135	0.25	Clear and clear
Example 6	42	129	0.12	Clear and clear
					Example 7	44	134	0.16	Clear and clear
Comparative example 1	28	115	0.26	Clear and clear
					Comparative example 2	31	121	0.23	Clear and clear

From table 2, the composite pipes of examples 1-7 all have better mechanical properties and lower friction coefficients, which indicates that the coating liquid of the invention can obtain better mechanical properties and reduced friction force, not only can reduce friction resistance in the pushing process of medicines or appliances, but also can reduce friction damage to blood vessels in the guiding process of the composite pipe, and can smoothly loose core of the polyimide composite pipe.

In addition, as can be seen from comparative example 1 and comparative examples 1 and 2, when graphite or carbon black is absent in the coating liquid, the comprehensive performance of the composite pipe is obviously reduced, which indicates that the synergistic effect exists among the graphite, the carbon black and other components, and the comprehensive performance of the material can be effectively improved.

Comparative example 1-example 3 is different in that the developer of example 1 is barium sulfate, the developer of example 2 is tungsten powder, the developer of example 3 is a mixture of tungsten powder and bismuth oxychloride, and in the coating liquid, the mass percentage concentration of the tungsten powder is 3% and the mass percentage concentration of the bismuth oxychloride is 2%. As can be seen from table 2, the friction coefficient of the composite pipe of example 2 and example 3 is greater than that of example 1, which indicates that the use of barium sulfate can reduce the friction coefficient of the pipe to some extent; the mechanical properties of the composite tubing of example 1, example 2 are better than those of example 3, indicating that the use of the developer can affect the overall properties of the tubing to some extent, and the developer is preferably barium sulfate.

Comparative example 1 and example 4 differ in that the core wire of example 1 is a stainless steel wire and the core wire of example 4 is a pure copper wire. As can be seen from table 2, the mechanical properties of the embodiment 4 are improved, and the core wires made of different materials and the coating layer have different acting forces, so that the pure copper wires are adopted as the core wires, the core pulling is more facilitated, and the damage to the coating layer in the core pulling process can be effectively reduced.

Comparative example 1 and example 5 the mass ratio of polytetrafluoroethylene to carbon black in the coating solution of example 1 was 2:1, and the mass percentage of polytetrafluoroethylene to carbon black in the coating solution of example 5 was 1:2. As can be seen from Table 2, the composite pipe of example 5 has lower performance than that of example 1, which shows that the mass percentage of polytetrafluoroethylene and carbon black has a certain influence on the performance of the composite pipe, and the mass ratio of polytetrafluoroethylene to carbon black in the coating liquid is preferably 2:1;

Comparative example 1 and example 6, example 6 did not employ staged programmed temperature rise for imidization; as can be seen from table 2, the mechanical properties and lubricity are reduced, which indicates that the adoption of the sectional program-controlled heating is beneficial to improving the imidization treatment effect;

Comparative example 1 and example 7 differ in the specific treatment temperatures of the staged programmed ramp up; from table 2, the lubricity of the composite pipe is reduced, which indicates that the reasonable selection of the processing temperature of the sectional program-controlled heating is beneficial to improving the lubricity of the composite pipe and improving the comprehensive performance of the composite pipe.

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims (10)

1. The preparation method of the composite pipe is characterized by comprising the following steps of:

obtaining a coating liquid, wherein the coating liquid consists of a polyimide precursor, polytetrafluoroethylene, graphite, carbon black and a developer;

coating the core wire at least once by using the coating liquid, and imidizing the coating liquid on the core wire after each coating;

core pulling is carried out to prepare the composite pipe;

Wherein, in the coating liquid, the mass percentage concentration of the polyimide precursor is 50-70%; the mass percentage concentration of the polytetrafluoroethylene is 5% -15%, the mass percentage concentration of the graphite is 5% -10%, and the mass percentage concentration of the carbon black is 2% -5%; the mass percentage concentration of the developer is 5% -10%; the mass ratio of the graphite to the polytetrafluoroethylene is 0.5-1; the mass ratio of the carbon black to the polytetrafluoroethylene is 0.2-0.8; the grain diameter of the polytetrafluoroethylene is 1-20 mu m;

The polyimide precursor is a prepolymer solution obtained after the reaction of aromatic dianhydride and aromatic diamine, and the molar ratio of the aromatic dianhydride to the aromatic diamine is 1:0.5-1:1; the aromatic dianhydride is selected from 3,4' -diphenyl ether tetracarboxylic dianhydride; the aromatic diamine is selected from 4,4' -diaminodiphenyl ether;

The imidization treatment comprises the following steps: sintering the coating liquid on the core wire in a sintering furnace, setting the sintering furnace to be at five-gear temperature and heating the temperature from low to high in a gradual mode, wherein the five-gear temperature ranges are as follows: 120 ℃, 200 ℃, 280 ℃, 300 ℃, 350 ℃.

2. The method for producing a composite pipe according to claim 1, wherein,

The particle size of the graphite is 1000-2000 meshes; and/or

The particle size of the carbon black is 1000-2000 meshes.

3. The method for producing a composite pipe according to claim 1, wherein the mass ratio of graphite to polytetrafluoroethylene in the coating liquid is 1.

4. The method for producing a composite pipe according to claim 1, wherein the mass ratio of carbon black to polytetrafluoroethylene in the coating liquid is 0.4 to 0.6.

5. The method of producing a composite pipe according to claim 1, wherein the viscosity of the prepolymer solution is 10 Pa-s to 100 Pa-s.

6. The method of producing a composite pipe according to claim 1 or 5, wherein the molar ratio of 3,4' -diphenylether tetracarboxylic dianhydride to diaminodiphenyl ether in the prepolymer solution is 1:1.

7. The method of producing a composite tubing according to claim 1, wherein the developer is selected from the group consisting of: one or more of barium sulfate, iodine preparation, tungsten powder and bismuth oxychloride.

8. The method of manufacturing a composite tubing according to claim 1, wherein the core wire is a stainless steel wire, a silver-plated copper wire or a pure copper wire.

9. The composite pipe is characterized by comprising the following components: polyimide precursors, polytetrafluoroethylene, graphite, and carbon black;

The composite pipe is prepared by the preparation method according to any one of claims 1 to 8.

10. The use of the composite tubing of claim 9 for the manufacture of interventional medical devices,

When the composite tube is applied to interventional medical treatment, friction on a blood vessel is involved in the process of introducing the composite tube;

the composite pipe is prepared by a method comprising the following steps:

obtaining a coating liquid, wherein the coating liquid consists of a polyimide precursor, polytetrafluoroethylene, graphite, carbon black and a developer;

coating the core wire at least once by using the coating liquid, and imidizing the coating liquid on the core wire after each coating;

core pulling is carried out to prepare the composite pipe;

Wherein, in the coating liquid, the mass percentage concentration of the polyimide precursor is 50-70%; the mass percentage concentration of the polytetrafluoroethylene is 5% -15%, and the mass percentage concentration of the carbon black is 2% -5%; the mass percentage concentration of the developer is 5% -10%.