Preparation method of PTFE (Polytetrafluoroethylene) pipe, PTFE inner pipe, pipe and application

Abstract

The invention relates to a preparation method of a PTFE (Polytetrafluoroethylene) pipe, a PTFE inner pipe, a pipe and application. According to the preparation method, PTFE micro powder and polymer-coated inorganic particles are mixed and subjected to curing, preforming, paste extrusion and sintering, the high-strength PTFE pipe can be prepared, and the polymer-coated inorganic particles comprise inorganic particles and alkene carboxylic ester polymers coating the surfaces of the inorganic particles. The preparation method can be used for preparing the high-strength thin-wall PTFE inner pipe.

Description

Technical Field

[0001] The invention relates to the technical field of medical devices, and in particular to a preparation method of a PTFE tube, a PTFE inner tube, the tube and applications. Background Art

[0002] Tetrafluoroethylene (PTFE) has excellent chemical stability, can withstand all strong acids, strong bases and strong oxidants, and does not react with various organic solvents. PTFE has a wide range of operating temperatures and can be used for a long time at 180℃~250℃ under normal pressure. It can be widely used in aerospace, medical, chemical, electronics, machinery, automobile, construction and other industries.

[0003] In the field of medical devices, PTFE is used in many tissue repair materials and artificial organ materials due to its excellent smoothness, water resistance, and biological inertness. For example, PTFE hoses are often used in artificial blood vessels, cannulas, catheters, pipettes, and endoscopes. PTFE tubing has good smoothness and is often used as the inner layer of kidney stone removal baskets, the inner layer of intracranial thrombus removal catheters, and the inner layer of cardiac interventional treatment channels. However, when PTFE tubing is used as an inner layer, the wall thickness is often thin, resulting in insufficient strength of the PTFE inner tube itself. For example, when used as the inner layer of the sheath of the stone removal basket, some instruments or stones brought out can easily scratch the PTFE inner layer when passing through the tube body cavity, causing the PTFE inner layer to break and be damaged. Therefore, it is necessary to improve the wear resistance of PTFE materials. In order to improve the wear resistance of PTFE materials, inorganic fillers such as silica, barium sulfate, aluminum oxide, etc. are usually added.

[0004] In the PTFE structure, fluorine atoms cover carbon chains to form a dense fluorine protective layer structure. This special structure gives PTFE many excellent properties, but it also makes it difficult to find a suitable solvent to dissolve PTFE well; and it is difficult for PTFE melt to change from a highly elastic state to a viscous flow state, and it is difficult to flow even if heated to the decomposition temperature. Therefore, the "insoluble and infusible" characteristics of PTFE make it difficult to form and secondary processing, and PTFE cannot be formed by conventional extrusion and injection molding methods. Currently, common PTFE processing methods include coating, molding, hydraulic pressure, extrusion, paste extrusion, etc., but it is often difficult to take into account strength, especially thin-walled PTFE is extremely difficult to achieve high strength.

[0005] At present, there is still a need to develop a processing method for PTFE pipes that takes into account both processing performance and material strength. Summary of the invention

[0006] In view of the problem that thin-walled PTFE inner tubes are often of low strength, the present invention aims to provide a method for preparing a PTFE tube, a PTFE inner tube, a tube and applications. The preparation method can be used to prepare a thin-walled PTFE inner tube with high strength.

[0007] In a first aspect of the present invention, a method for preparing a PTFE tube is provided, comprising the following steps:

[0008] The coupling agent-modified inorganic particles and the unsaturated reaction monomer are mixed in a mass ratio of (0.1-0.2):1, and reacted under polymerization conditions to prepare polymer-coated inorganic particles; wherein the unsaturated reaction monomer is an olefin carboxylate containing a reactive carbon-carbon double bond;

[0009] The PTFE powder, the polymer-coated inorganic particles and the auxiliary oil are mixed to prepare a premix; wherein the mass ratio of the polymer-coated inorganic particles to the PTFE powder is 0.1% to 3%;

[0010] The premix is ​​subjected to a aging treatment to obtain a mixed material;

[0011] Preforming the mixed material into a blank;

[0012] Extruding the blank into a paste to obtain a hollow raw tube;

[0013] The raw material tube is sintered to obtain a PTFE tube.

[0014] In some embodiments, the single wall thickness of the PTFE tube is 0.02 mm to 0.8 mm.

[0015] In some embodiments, the preparation method meets one or more of the following characteristics:

[0016] The inner diameter of the hollow raw material tube is 1 mm to 7 mm;

[0017] The single wall thickness of the hollow raw material tube is 0.02 mm to 0.5 mm;

[0018] The inner diameter of the PTFE tube is 1 mm to 7 mm;

[0019] The single wall thickness of the PTFE tube is 0.02 mm to 0.5 mm;

[0020] The blank is cylindrical, and the PTFE tube is a hollow circular tube.

[0021] In some embodiments, the preparation method meets one or more of the following characteristics:

[0022] The inorganic particles in the coupling agent-modified inorganic particles are selected from one or more of silicon dioxide, glass powder, aluminum oxide and titanium dioxide;

[0023] The average particle size of the inorganic particles in the coupling agent-modified inorganic particles is 0.1 μm to 200 μm;

[0024] The coupling agent in the coupling agent-modified inorganic particles is selected from one or more of silanes, phthalates and alkyls;

[0025] The unsaturated reactive monomer is selected from one or more of alkyl acrylate and alkyl methacrylate;

[0026] In the polymer-coated inorganic particles, the mass proportion of the polymer component is 80% to 98%;

[0027] The average particle size of the coupling agent modified inorganic particles is 0.1 μm to 200 μm;

[0028] The average particle size of the PTFE micropowder is 300 μm to 600 μm.

[0029] In some embodiments, the preparation method meets one or more of the following characteristics:

[0030] The coupling agent modified inorganic particles are silane coupling agent modified silicon dioxide particles;

[0031] The unsaturated reactive monomer is one or more of methyl methacrylate and ethyl methacrylate.

[0032] In some embodiments, the coupling agent in the coupling agent-modified inorganic particles is an amino silane coupling agent.

[0033] In some embodiments, the preparation method meets one or more of the following characteristics:

[0034] The reaction under polymerization conditions includes: carrying out polymerization reaction at 60° C. to 180° C. for 10 h to 24 h in the presence of a solvent and a catalyst;

[0035] After the reaction under polymerization conditions is completed, the following post-treatment steps are also included: cooling, filtering, and drying;

[0036] The mass of the auxiliary oil is 14% to 25% of the sum of the mass of the PTFE micropowder and the polymer-coated inorganic particles;

[0037] Mixing the PTFE micropowder, the polymer-coated inorganic particles and the auxiliary oil comprises: mixing the PTFE micropowder and the polymer-coated inorganic particles at high speed for 15 minutes to 45 minutes, adding the auxiliary oil and mixing at high speed for 15 minutes to 45 minutes; wherein the speed of each high-speed mixing is independently 800 rpm to 1600 rpm;

[0038] The auxiliary oil is selected from one or more of Isopar H, Isopar G, aviation kerosene and naphtha;

[0039] The conditions for the aging treatment include: treating at 32°C to 37°C for 12h to 24h, treating at 22°C to 28°C for 12h to 24h

[0040] Before the mixed material is subjected to preforming treatment, the auxiliary oil is firstly removed by heating at 100° C. to 250° C.;

[0041] The conditions for performing the preforming treatment include: pressing at 20°C to 40°C with a pressing speed of 200mm / min to 350mm / min;

[0042] The volume ratio of the mixed material to the blank is (2-3):1;

[0043] The compacted density of the blank is 1 g / cm 3 ~3g / cm 3 ;

[0044] The conditions for the paste extrusion treatment include: at 40°C to 80°C, an extrusion speed of 1mm / min to 50mm / min, and a pulling speed of 1m / min to 10m / min;

[0045] The conditions for the sintering treatment include: sintering at 100° C. to 490° C. for 1 min to 10 min in an air atmosphere.

[0046] In some embodiments, the preparation method meets one or more of the following characteristics:

[0047] The coupling agent modified inorganic particles are silane coupling agent modified silica particles; the silane coupling agent modified silica particles are prepared by a method comprising the following steps: mixing a mixed solution A1 in which silica particles are uniformly dispersed with an aqueous solution B1 containing a silane coupling agent, adjusting the pH value to be weakly acidic at 5.0 to 6.5, performing a silylation coupling reaction for 0.5 to 3 hours, filtering and separating, washing with water, washing with anhydrous ethanol, and drying at 60° C. to 120° C. for 3 to 12 hours to obtain silane coupling agent modified silica particles; wherein the solvent in the mixed solution A1 is a mixed solvent of water and ethanol at a mass ratio of (1 to 1.5):1;

[0048] The unsaturated reactive monomer is selected from one or more of alkyl acrylate and alkyl methacrylate;

[0049] The reaction under polymerization conditions comprises: stirring and reacting at 60°C to 80°C for 10h to 15h in the presence of a solvent and a catalyst; wherein the solvent is selected from C 1-10 One or more of aliphatic alcohol solvents and benzene solvents, wherein the aliphatic alcohol solvent is C1-10 Fatty alcohol or C 1-10 A co-mixed solvent of fatty alcohol and water, wherein the benzene solvent is one or more of benzene and its alkyl substituents; the amount of the solvent is 5 to 10 times the mass of the unsaturated reaction monomer; the mass of the catalyst is 1% to 3% relative to the mass of the unsaturated reaction monomer.

[0050] In a second aspect of the present invention, a PTFE inner tube is provided, which is prepared by the preparation method described in the first aspect of the present invention.

[0051] In a third aspect of the present invention, a pipe is provided, which comprises the PTFE inner pipe according to the second aspect of the present invention.

[0052] In the fourth aspect of the present invention, there is provided use of the PTFE inner tube described in the second aspect of the present invention or the tube described in the third aspect of the present invention in the preparation of medical tubes.

[0053] In the preparation method provided by the present invention, polymer-coated inorganic particles are added to PTFE micropowder, and high-strength PTFE pipes are prepared through aging, preforming, paste extrusion and sintering. The method can be used to prepare high-strength thin-walled PTFE inner tubes (for example, single-wall thickness is 20 to 800 μm). The polymer-coated inorganic particles are in-situ coated with inorganic particles by in-situ polymerization. The inorganic particles are first treated with a coupling agent so that the inorganic particles have the property of being organic-friendly, and then mixed with an olefin carboxylate monomer containing a reactive carbon-carbon double bond, and in-situ polymerization is performed to form an olefin carboxylate polymer. The olefin carboxylate polymer is tightly and stably wrapped on the surface of the inorganic particles by the van der Waals force between the coupling agent and the olefin carboxylate polymer. By doping polymer-coated inorganic particles to process PTFE into pipes, the processing performance of PTFE pipes can be significantly improved while giving the PTFE pipes higher strength. In addition, using this preparation method, even if thin-walled PTFE is prepared, high strength can still be obtained. Further, the high-strength thin-walled PTFE can be a PTFE inner tube. This is because the polymer-coated inorganic particles have suitable compatibility with PTFE micropowders, which play a role in better dispersing inorganic particles during the preparation process, and the inorganic particle core plays a reinforcing role.

[0054] The preparation method provided by the present invention can significantly improve the problems of poor wear resistance, insufficient strength, easy scratching, etc. of the PTFE tube in the traditional process.

[0055] The PTFE inner tube prepared by the above method has high precision, stable size, smooth surface, and good strength. The tube is not easy to be kinked and has good operation and use feeling.

[0056] The method mentioned in the present invention has simple process and can be used for continuous and large-scale production.

[0057] The PTFE pipe can also be prepared by one-step pasty extrusion molding. The paste extrusion molding method provided by the present invention has a simple manufacturing process and low cost. The molded pipe has high strength, high precision and good flexibility. The problem of easy wear and tear of the PTFE inner pipe in the traditional process is significantly improved.

[0058] In addition, the method for preparing a PTFE tube based on one-step molding by paste extrusion provided by the present invention can be applied to products of various specifications that can be produced by paste extrusion equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] In order to more clearly illustrate the technical solutions in the embodiments of the present application and to more completely understand the present application and its beneficial effects, the following is a brief introduction to the drawings required for the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present application, and those skilled in the art can obtain other drawings based on these drawings without creative work.

[0060] Figure 1 The figure is a schematic diagram of the preparation process of PTFE tube in one embodiment of the present invention. DETAILED DESCRIPTION

[0061] The present invention will be further described in detail below in conjunction with the accompanying drawings, embodiments and examples. It should be understood that these embodiments and examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. The purpose of providing these embodiments and examples is to make the understanding of the disclosure of the present invention more thorough and comprehensive. It should also be understood that the present invention can be implemented in many different forms and is not limited to the embodiments and examples described herein. Those skilled in the art can make various changes or modifications without violating the connotation of the present invention, and the equivalent forms obtained also fall within the protection scope of the present invention. For example, the features described or described as part of an embodiment can be combined in another embodiment in a suitable manner to produce a new embodiment. In addition, in the description below, a large number of specific details are given in order to provide a more comprehensive understanding of the present invention. It should be understood that the present invention can be implemented without one or more of these details.

[0062] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in the specification of the present invention herein are only for the purpose of describing implementation modes and embodiments and are not intended to limit the present invention.

[0063] the term

[0064] Unless otherwise specified or incompatible herewith, the terms and phrases used herein shall have the following meanings:

[0065] The term "and / or" used herein includes any one of two or more related listed items, and also includes any and all combinations of the related listed items, wherein the any and all combinations include any combination of two related listed items, any more related listed items, or all related listed items. For example, "A and / or B" includes three parallel solutions: A, B, and "a combination of A and B".

[0066] In the present invention, "plurality", "multiple", "multiple times", etc., unless otherwise specified, refer to a number greater than 2 or equal to 2. For example, "one or more" means one or greater than or equal to two.

[0067] In the present invention, unless otherwise specified, "one or more" means any one of the listed items or any combination of the listed items. Similarly, "one or more" and other expressions that mean "one or more" are also understood in the same way unless otherwise specified.

[0068] As used herein, "combination thereof", "any combination thereof", "any combination thereof" etc. include all suitable combinations of any two or more of the listed items.

[0069] Herein, the “suitable” mentioned in “suitable combination”, “suitable method”, “any suitable method”, etc., shall be based on the ability to implement the technical solution of the present invention, solve the technical problem of the present invention, and achieve the expected technical effect of the present invention.

[0070] Herein, "preferred", "better", "more preferred" and "suitable" are only used to describe implementation methods or examples with better effects, and it should be understood that they do not constitute a limitation on the scope of protection of the present invention. If multiple "preferred" items appear in a technical solution, unless otherwise specified and there is no contradiction or mutual restriction, each "preferred" item is independent.

[0071] In the present invention, "further", "further", "particularly", "for example", "such as", "example", "for example", etc. are used for descriptive purposes, indicating that the previous and subsequent different technical solutions are related in terms of the contents covered, but should not be understood as limiting the previous technical solution, nor can they be understood as limiting the scope of protection of the present invention. In the present invention, unless otherwise specified, A (such as B) means that B is a non-limiting example of A, and it can be understood that A is not limited to B.

[0072] In the present invention, "optionally", "optional", and "optional" mean optional, that is, any one of the two parallel schemes of "yes" or "no". If multiple "optional" appear in a technical scheme, unless otherwise specified and there is no contradiction or mutual restriction, each "optional" is independent of each other. In this application, descriptions such as "optionally contain", "optionally include", etc. mean "contain or not contain". "Optional component X" means that component X exists or does not exist, or means that component X is contained or not contained.

[0073] In the present invention, in the "first aspect", "second aspect", "third aspect", "fourth aspect", etc., the terms "first", "second", "third", "fourth", etc. are used only for descriptive purposes and cannot be understood as indicating or implying relative importance or quantity, nor can they be understood as implicitly indicating the importance or quantity of the indicated technical features. Moreover, "first", "second", "third", "fourth", etc. only serve the purpose of non-exhaustive enumeration and description, and it should be understood that they do not constitute a closed limitation on quantity.

[0074] As used herein, the terms "comprising", "including" and "comprising" are synonymous and are inclusive or open-ended and do not exclude additional, unrecited members, elements or method steps.

[0075] In the present invention, the technical features described in an open manner include closed technical solutions composed of the listed features, and also include open technical solutions containing the listed features.

[0076] In the present invention, when it comes to a numerical interval (i.e., a numerical range), unless otherwise specified, the distribution of the optional numerical values ​​in the numerical interval is considered to be continuous, and includes the two numerical endpoints (i.e., the minimum value and the maximum value) of the numerical interval, and each numerical value between the two numerical endpoints. Unless otherwise specified, when the numerical interval only refers to the integers in the numerical interval, including the two endpoint integers of the numerical range, and each integer between the two endpoints, is equivalent to directly listing each integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed herein should be understood to include any and all sub-ranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, a percentage, a ratio, etc. "Numerical interval" allows broadly including numerical interval types such as percentage intervals, ratio intervals, and ratio intervals.

[0077] The temperature parameters in the present invention, if not specifically limited, are allowed to be either constant temperature treatment or to vary within a certain temperature range. It should be understood that the constant temperature treatment allows the temperature to fluctuate within the precision range controlled by the instrument. Fluctuations within the range of ±5°C, ±4°C, ±3°C, ±2°C, and ±1°C are allowed.

[0078] In the present invention, the term "room temperature" or "normal temperature" generally refers to 4°C to 35°C, for example, 20°C ± 5°C. In some embodiments of the present invention, "room temperature" or "normal temperature" refers to 10°C to 30°C. In some embodiments of the present invention, "room temperature" or "normal temperature" refers to 20°C to 30°C.

[0079] In the present invention, when it comes to the unit of the data range, if there is a unit only after the right endpoint, it means that the units of the left endpoint and the right endpoint are the same. For example, 3-5h means that the units of the left endpoint "3" and the right endpoint "5" are both h (hours).

[0080] All documents mentioned in the present invention are cited as references in this application, just as each document is cited as a reference separately. Unless they conflict with the invention purpose and / or technical solution of the present application, the cited documents involved in the present invention are cited with all contents and all purposes. When the present invention involves cited documents, the definitions of relevant technical features, terms, nouns, phrases, etc. in the cited documents are also cited. When the present invention involves cited documents, the examples and preferred embodiments of the cited relevant technical features may also be incorporated into this application as references, but are limited to the ability to implement the present invention. It should be understood that when the content of the citation conflicts with the description in this application, the present application shall prevail or be modified adaptively according to the description of this application.

[0081] In the present invention, if there are multiple steps involved in the method flow, unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and they can be executed in other orders than described. Moreover, any step can include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and their execution order is not necessarily sequential, but can be executed in turn, alternating or simultaneously with other steps or parts of sub-steps or stages of other steps.

[0082] The mass or weight of the relevant components mentioned in the description of the embodiments of the present invention may not only refer to the specific content of each component, but also indicate the proportional relationship of the mass or weight between the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the description of the embodiments of the present invention, it is within the scope disclosed in the description of the embodiments of the present invention. Specifically, the mass or weight described in the description of the embodiments of the present invention may be units known in the chemical industry such as μg, mg, g, and kg.

[0083] In a first aspect of the present invention, a method for preparing a PTFE tube is provided, which comprises the following steps (see Figure 1 ):

[0084] S100: preparing polymer-coated inorganic particles;

[0085] S200: mixing PTFE micropowder, the polymer-coated inorganic particles and auxiliary oil to prepare a premix;

[0086] S300: performing a aging treatment on the premix to obtain a mixture;

[0087] S400: preforming the mixed material into a blank;

[0088] S500: Extruding the blank into a paste to obtain a hollow raw tube;

[0089] S600: Sintering the raw material tube to obtain a PTFE tube.

[0090] In some embodiments, a method for preparing a PTFE tube is provided, comprising the following steps:

[0091] S100: mixing the coupling agent-modified inorganic particles and the unsaturated reactive monomers, and reacting them under polymerization conditions to prepare polymer-coated inorganic particles; wherein the unsaturated reactive monomers contain reactive carbon-carbon double bonds;

[0092] Optionally, the coupling agent-modified inorganic particles and the unsaturated reactive monomers are mixed in a mass ratio of (0.1 to 0.2):1 (equivalent to a mass ratio of 1:10 to 1:5);

[0093] S200: mixing PTFE micropowder, the polymer-coated inorganic particles and auxiliary oil to prepare a premix;

[0094] Optionally, the mass ratio of the polymer-coated inorganic particles to the PTFE micropowder is 0.1% to 3%;

[0095] S300: performing a aging treatment on the premix to obtain a mixture;

[0096] S400: preforming the mixed material into a blank;

[0097] S500: Extruding the blank into a paste to obtain a hollow raw tube;

[0098] S600: Sintering the raw material tube to obtain a PTFE tube.

[0099] In some embodiments, the single wall thickness of the PTFE tube is 0.02 mm to 0.8 mm.

[0100] In the preparation method provided by the present invention, polymer-coated inorganic particles are added to PTFE micropowder, and high-strength PTFE pipes are prepared through aging, preforming, paste extrusion and sintering. The method can be used to prepare high-strength thin-walled PTFE inner tubes (for example, single-wall thickness is 20 to 800 μm). The polymer-coated inorganic particles are in-situ coated with inorganic particles by in-situ polymerization. The inorganic particles are first treated with a coupling agent so that the inorganic particles have an organic affinity, and then mixed with an olefinic carboxylate monomer containing a reactive carbon-carbon double bond, and in-situ polymerization is performed to form an olefinic carboxylate polymer. The olefinic carboxylate polymer is tightly and stably wrapped on the surface of the inorganic particles by the van der Waals force between the coupling agent and the olefinic carboxylate polymer. By doping polymer-coated inorganic particles to process PTFE into pipes, the processing performance of PTFE pipes can be significantly improved while giving the PTFE pipes higher strength. In addition, using this preparation method, even if thin-walled PTFE is prepared, high strength can still be obtained. Further, the high-strength thin-walled PTFE can be a PTFE inner tube. This is because the polymer-coated inorganic particles have suitable compatibility with PTFE micropowders, which play a role in better dispersing inorganic particles during the preparation process, and the inorganic particle core plays a reinforcing role.

[0101] S100: preparing polymer-coated inorganic particles.

[0102] In step S100 , polymer-coated inorganic particles are prepared.

[0103] In some implementations, step S100 includes the following steps S120 and S140:

[0104] S120: mixing the coupling agent-modified inorganic particles and the unsaturated reactive monomer; wherein the unsaturated reactive monomer contains reactive carbon-carbon double bonds;

[0105] S140, reacting under polymerization conditions to prepare polymer-coated inorganic particles.

[0106] In the present application, unless otherwise specified, "polymer-coated inorganic particles" include inorganic particles and olefin carboxylate polymers coated on the surface of the inorganic particles. The coating can be physical coating. Physical coating means that the olefin carboxylate polymer is in physical contact with the inorganic particles. The olefin carboxylate polymer is coated on at least a portion of the surface of the inorganic particles, and preferably the inorganic particles are completely wrapped inside to form a core-shell structure. In some embodiments, the polymer-coated inorganic particles are a core-shell structure, the inorganic particles are located in the inner core, and the olefin carboxylate polymer is located in the outer shell.

[0107] In some embodiments, in step S100, the coupling agent-modified inorganic particles and unsaturated reactive monomers are mixed and reacted under polymerization conditions to prepare polymer-coated inorganic particles, wherein the unsaturated reactive monomer is an olefin carboxylate containing a reactive carbon-carbon double bond.

[0108] Coupling agent modified inorganic particles

[0109] In the present invention, unless otherwise specified, "coupling agent modified inorganic particles" refer to inorganic particles with coupling agents grafted on the surface. Through coupling agent modification, the amphiphilic characteristics of the coupling agent can be used to make the inorganic particles have the property of being affinity for organic substances, so that the generated polymer can be evenly and tightly coated on the surface of the inorganic particles in the subsequent in-situ polymerization reaction.

[0110] In some embodiments, the inorganic particles in the coupling agent-modified inorganic particles are selected from one or more of silicon dioxide, glass powder, aluminum oxide, and titanium dioxide.

[0111] In some embodiments, the coupling agent in the coupling agent-modified inorganic particles is selected from one or more of silanes, phthalates and alkyls. The affinity between the inorganic particles and the reaction monomers and the polymerization products can be improved by selecting a suitable coupling agent according to the type of inorganic particles and the inorganic particles used to coat the inorganic particles, so as to better coat the polymer uniformly and tightly on the surface of the inorganic particles through in-situ polymerization. Those skilled in the art can select a suitable coupling agent according to the type of inorganic particles, thereby giving the inorganic particles good affinity for organic matter. Taking the inorganic particles as silicon dioxide as an example, the corresponding coupling agent can preferably include a silane coupling agent.

[0112] In some embodiments, the coupling agent in the coupling agent-modified inorganic particles is a silane coupling agent, and in this case, the coupling agent-modified inorganic particles are silane coupling agent-modified silica particles. Compared with some other types of coupling agents, silane coupling agents can provide better affinity for organic matter.

[0113] In some embodiments, the coupling agent in the coupling agent-modified inorganic particles is an amino silane coupling agent, and in this case, the inorganic particles in the coupling agent-modified inorganic particles are grafted with amino groups through the coupling agent. In this case, the hydrophilicity of the particles can be improved, which is conducive to more uniform dispersion of the inorganic particles in the mixed solution A (such as the mixed solution A1) and the polymerization system, thereby facilitating a more uniform coating of the polymer generated by in-situ polymerization on the surface of the inorganic particles.

[0114] In some embodiments, the average particle size of the inorganic particles in the coupling agent-modified inorganic particles is 0.1 μm to 200 μm. The average particle size of the inorganic particles in the coupling agent-modified inorganic particles can also be any of the following particle sizes or a range consisting of any two of the following particle sizes: 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm , 4.5μm, 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, 8.5μm, 9μm, 9.5μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 120μm, 150μm, 160μm, 180μm, etc. In some embodiments, the average particle size of the inorganic particles in the coupling agent-modified inorganic particles can also be selected from any suitable range as follows: 0.1μm to 1μm. When the average particle size of the inorganic particles in the coupling agent-modified inorganic particles is less than or equal to 1 micron, the inorganic particles can also be recorded as "nano inorganic particles".

[0115] In some embodiments, the average particle size of the coupling agent modified inorganic particles is 0.1 μm to 200 μm. The average particle size of the coupling agent modified inorganic particles can also be any of the following particle sizes or an interval consisting of any two of the following particle sizes: 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5 μm, 4 μm, 4.5 μm, 5 μm, 5 .5μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, 8.5μm, 9μm, 9.5μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 120μm, 150μm, 160μm, 180μm, etc., for example, can be selected from the following range: 0.1μm~1μm.

[0116] In some embodiments, the coupling agent-modified inorganic particles can be prepared by a method including the following step S110: mixing a mixed solution A in which inorganic particles are uniformly dispersed with an aqueous solution B containing a coupling agent, performing a coupling reaction under appropriate pH conditions, separating by suction, washing, and drying to obtain coupling agent-modified inorganic particles.

[0117] The type and size of the inorganic particles in the mixed solution A may be, but are not limited to, "inorganic particles in coupling agent-modified inorganic particles". The type of the coupling agent in the aqueous solution B may be, but is not limited to, "coupling agent in coupling agent-modified inorganic particles".

[0118] In some embodiments, the volume ratio of the mixed solution A to the aqueous solution B is (1-5):1, for example, 1:1, 2:1, 3:1, 4:1, 5:1, etc.

[0119] In some embodiments, the coupling agent-modified inorganic particles are silane coupling agent-modified silica particles, which can be prepared by a method comprising the following step S1102: mixing a mixed solution A1 in which silica particles are uniformly dispersed with an aqueous solution B1 containing a silane coupling agent, adjusting the pH value to be weakly acidic (such as pH 5.0-6.5), performing a silanization coupling reaction for 0.5h-3h (optionally, performing a silanization coupling reaction under heating conditions in a water bath), separating by suction filtration, washing with water, washing with anhydrous ethanol, and drying at 60°C-120°C for 3h-12h to obtain silane coupling agent-modified silica particles; wherein the solvent in the mixed solution A1 is a mixed solvent of water and ethanol (which can be recorded as a water / ethanol solvent), and further optionally, the solvent in the mixed solution A1 can be a mixed solvent of water and ethanol in a mass ratio of (1-1.5):1, and the mass ratio of water to ethanol can be 1:1, 1.2:1, 1.5:1, etc.

[0120] When preparing the mixed solution A1, the mass ratio of the silica particles to the solvent (such as a water / ethanol mixed solvent) can be 1:(5-10), that is, 1:5 to 1:10, for example, 1:5, 1:6, 1:7, 1:8, 1:9, 1:10, etc.

[0121] When preparing the aqueous solution B1, the volume ratio of the coupling agent to water can be 4:5 to 6:5 (eg, 4:5, 5:5, 6:5, etc.).

[0122] In some embodiments, the volume ratio of the mixed solution A1 to the aqueous solution B1 is (1-5):1, for example, 1:1, 2:1, 3:1, 4:1, 5:1, etc.

[0123] Furthermore, in step S1102, the weak acidity in "adjusting the pH value to weak acidity" may be pH 5.0-6.5, which is more conducive to the coupling reaction between the silane coupling agent and the silica particles. Acetic acid and sodium hydroxide may be used to adjust the pH value.

[0124] In some embodiments, the mixed solution A may be mixed solution A1.

[0125] In some embodiments, the aqueous solution B may be aqueous solution B1.

[0126] In some embodiments, the inorganic particles in the mixed solution A (such as mixed solution A1) are nano-silicon dioxide, and further, the average particle size can be 0.1 to 200 μm, and can also be any of the following particle sizes or an interval consisting of any two of the following particle sizes: 0.1 μm, 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.6 μm, 0.7 μm, 0.8 μm, 0.9 μm, 1 μm, 1.5 μm, 2 μm, 2.5 μm, 3 μm, 3.5μm, 4μm, 4.5μm, 5μm, 5.5μm, 6μm, 6.5μm, 7μm, 7.5μm, 8μm, 8.5μm, 9μm, 9.5μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, 100μm, 120μm, 150μm, 160μm, 180μm, etc., for example, can be selected from the following range: 0.1μm~1μm.

[0127] Unsaturated reactive monomer

[0128] In the present invention, unless otherwise specified, the unsaturated reactive monomer in step S100 is an olefinic carboxylic acid ester containing a reactive carbon-carbon double bond.

[0129] In some embodiments, the number of reactive carbon-carbon double bonds in the unsaturated reactive monomer is 1, and the polymer product formed thereby is chain-like, and the polymer product can be dissolved in a corresponding solvent. In the present invention, unless otherwise specified, "reactive carbon-carbon double bonds" refer to carbon-carbon double bonds that can undergo addition polymerization.

[0130] In the present invention, unless otherwise specified, "olefin carboxylate" refers to a carboxylate containing a reactive carbon-carbon double bond, which may include, but is not limited to, one or more of acrylate, methacrylate, and olefin carboxylate analogs of any of the foregoing compounds. Compared to olefin carboxylic acid monomers and corresponding polymers (such as acrylic acid and polyacrylic acid), olefin carboxylate and its polymers have the advantages of high activity, high purity, and less stringent requirements on reaction ratio.

[0131] It is understood that the olefinic carboxylates of the present invention contain reactive carbon-carbon double bonds and carboxylate groups.

[0132] In some embodiments, the structure of the carboxylate group in the olefin carboxylate is -C(=O)OR, wherein R may be, but is not limited to, an alkyl group (corresponding to an olefin carboxylate alkyl group), and may further be C 1-8 Alkyl, further can be C 1-6 Alkyl, further can be C 1-4 Alkyl, further can be methyl, ethyl, propyl or butyl. In some embodiments, R is methyl, corresponding to carboxymethyl ester.

[0133] In some embodiments, the structure of the carboxylate group is carboxymethyl ester, which has the structure -C(=O)OCH3.

[0134] In some embodiments, the structure of the unsaturated reactive monomer is CH2=CH(R1)-C(=O)OR, where R is defined as above, and R1 is H or C 1-3 Alkyl, further, R1 is H or methyl. In some embodiments, R1 is H. In some embodiments, R1 is methyl.

[0135] Herein, the term "alkyl" refers to a monovalent residue formed by the loss of a hydrogen atom from a saturated hydrocarbon containing a primary (normal) carbon atom, a secondary carbon atom, a tertiary carbon atom, a quaternary carbon atom, or a combination thereof. A phrase containing the term, for example, "C1-9 alkyl" refers to an alkyl containing 1 to 9 carbon atoms, and each occurrence may be independently C1 alkyl, C2 alkyl, C3 alkyl, C4 alkyl, C5 alkyl, C6 alkyl, C7 alkyl, C8 alkyl or C9 alkyl. Suitable examples include, but are not limited to, methyl (Me, -CH3), ethyl (Et, -CH2CH3), 1-propyl (n-Pr, n-propyl, -CH2CH2CH3), 2-propyl (i-Pr, i-propyl, -CH(CH3)2), 1-butyl (n-Bu, n-butyl, -CH2CH2CH2CH3), 2-methyl-1-propyl (i-Bu, i-butyl, -CH2CH(CH3)2), 2-butyl (s-Bu, s-butyl, -CH(C H3)CH2CH3), 2-methyl-2-propyl (t-Bu, t-butyl, -C(CH3)3), 1-pentyl (n-pentyl, -CH2CH2CH2CH2CH3), 2-pentyl (-CH(CH3)CH2CH2CH3), 3-pentyl (-CH(CH2CH3)2), 2-methyl-2-butyl (-C(CH3)2CH2CH3), 3-methyl-2-butyl (-CH(CH3)CH(CH3)2), 3-methyl-1-butyl (- CH2CH2CH(CH3)2), 2-methyl-1-butyl (-CH2CH(CH3)CH2CH3), 1-hexyl (-CH2CH2CH2CH2CH2CH3), 2-hexyl (-CH(CH3)CH2CH2CH2CH3), 3-hexyl (-CH(CH2CH3)(CH2CH2CH3)), 2-methyl-2-pentyl (-C(CH3)2CH2CH2CH3), 3-methyl-2-pentyl (-CH(CH3)CH( 2), 2-methyl-3-pentyl (-CH(CH2CH3)CH(CH3)2), 2,3-dimethyl-2-butyl (-C(CH3)2CH(CH3)2), 3,3-dimethyl-2-butyl (-CH(CH3)C(CH3)3 and octyl (-(CH2)7CH3).

[0136] In some embodiments, the unsaturated reactive monomer is selected from one or more of alkyl acrylates and alkyl methacrylates. In the alkyl acrylate, R1 is H, R is an alkyl group, and R can further be an alkyl group as defined above. In the alkyl methacrylate, R1 is a methyl group, R is an alkyl group, and R can further be an alkyl group as defined above.

[0137] In some embodiments, the unsaturated reactive monomer is an alkyl methacrylate.

[0138] In some embodiments, the unsaturated reactive monomer is one or more of methyl methacrylate and ethyl methacrylate.

[0139] In some embodiments, the unsaturated reactive monomer is methyl methacrylate.

[0140] Raw material mixing (S120)

[0141] In some embodiments, in step S100, in the step of "mixing the coupling agent modified inorganic particles and the unsaturated reactive monomers", the coupling agent modified inorganic particles and the unsaturated reactive monomers are mixed at a mass ratio of (0.1-0.2):1 (i.e., mixed at a mass ratio of 1:(10-5)). The mass ratio of the coupling agent modified inorganic particles and the unsaturated reactive monomers can also be any of the following ratios, or an interval consisting of any two of the following ratios: 0.1:1 (i.e., 1:10), 0.15:1, 1:6, 1:7, 1:7.5, 1:8, 1:9, 0.2:1 (i.e., 1:5), etc. In the present application, the doping amount of the coupling agent modified inorganic particles is crucial to the preparation of high-strength thin-walled PTFE pipes. If the amount of coupling agent modified inorganic particles added is too little or not added, the mechanical properties of the PTFE pipe cannot be significantly improved or cannot be improved; if the amount of coupling agent modified inorganic particles added is too much, the overall compatibility with PTFE micropowder will deteriorate, which will cause the extruded pipe to be easily brittle.

[0142] In the present invention, different steps have strong synergistic effects. For example, if the ratio of the amount of the coupling agent-modified inorganic particles and the unsaturated reactive monomer in step S120 is changed, the coating amount of the polymer will be changed, thereby affecting the mechanical properties of the pipe in the subsequent extrusion step.

[0143] In situ polymerization (S140)

[0144] In some embodiments, step S100 includes the following step S140: reacting under polymerization conditions to prepare polymer-coated inorganic particles. Through the polymerization reaction, olefin carboxylate polymers are in situ generated on the surface of the inorganic particles, thereby coating the surface of the inorganic particles.

[0145] It can be understood that the "polymerization conditions" in step S100 refer to conditions suitable for the polymerization reaction of reactive carbon-carbon double bonds.

[0146] In some embodiments, step S140 includes S1402: in the presence of a solvent and a catalyst, a polymerization reaction is carried out using the reactive carbon-carbon double bonds in the unsaturated reaction monomer to generate an olefin carboxylate polymer coated on the surface of the coupling agent-modified inorganic particles. The olefin carboxylate polymer includes a linear polyolefin main chain and a carboxylate side group. The linear polyolefin main chain is composed of carbon atoms and has a certain flexibility, and a plurality of carboxylate groups are located on the side groups of the linear main chain.

[0147] In some embodiments, a suitable catalyst type can be selected according to the type of unsaturated reaction monomer, for example, it can be but not limited to an azo catalyst. In some embodiments, the catalyst can include azobisisobutyronitrile (AIBN), and further can be AIBN.

[0148] In some embodiments, reacting under polymerization conditions includes: performing polymerization in the presence of a solvent and a catalyst. Those skilled in the art can flexibly adjust polymerization conditions, such as polymerization temperature and time, according to factors such as the reactivity of the reaction monomers, the boiling point of the solvent, the catalytic activity of the catalyst, and the stability of the polymer-coated inorganic particles. For example, the polymerization temperature can be 60°C to 180°C, 60°C, 65°C, 70°C, 75°C, 80°C, 100°C, 120°C, 150°C, etc. For example, the polymerization time can be 10h to 24h, such as 10h, 11h, 12h, 13h, 14h, 15h, 16h, 18h, 20h, 24h, etc.

[0149] In some embodiments, in step S140 or step S1402, the amount of the solvent may be 5 to 10 times, for example 5, 6, 7, 8, 9, or 10 times, the mass of the unsaturated reaction monomer.

[0150] In some embodiments, in step S140 or step S1402, the percentage of the mass of the catalyst relative to the mass of the unsaturated reaction monomer can be 1% to 3%, or can be any of the following percentages or an interval consisting of any two of the following percentages: 1%, 1.2%, 1.4%, 1.5%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.5%, 2.6%, 2.8%, 3%, etc.

[0151] In some embodiments, conducting the reaction under polymerization conditions includes conducting the polymerization reaction under a stir bar.

[0152] In some embodiments, carrying out the reaction under polymerization conditions includes carrying out the polymerization reaction in the presence of a solvent and a catalyst and under stirring conditions.

[0153] In some embodiments, reacting under polymerization conditions includes: conducting a polymerization reaction at 60°C to 180°C for 10 hours to 24 hours in the presence of a solvent and a catalyst, and further, the mass ratio of the coupling agent-modified inorganic particles to the unsaturated reaction monomer is (0.1 to 0.2):1.

[0154] In some embodiments, in step S140, the initial mass ratio of the coupling agent modified inorganic particles, the solvent, the unsaturated reaction monomer and the catalyst is (0.1-0.2): (5-10): 1: (1%-3%). The mass ratio of the coupling agent modified inorganic particles, the solvent and the catalyst to the unsaturated reaction monomer can also be independently or in any suitable combination to be the range or value in any embodiment of the present invention.

[0155] In some embodiments, reacting under polymerization conditions includes: conducting a polymerization reaction in the presence of a solvent and a catalyst, and further, stirring the reaction at 60°C to 80°C for 10h to 15h. The reaction temperature can be 60°C to 80°C, such as 60°C, 65°C, 70°C, 75°C, 80°C, etc. The reaction time can be 10h to 15h, such as 10h, 11h, 12h, 13h, 14h, 15h, etc. The solvent can be selected from but not limited to one or more of alcohol solvents and benzene solvents. The solvent can be an alcohol solvent or a benzene solvent. The alcohol solvent can be a fatty alcohol solvent, and further can be C 1-10 Fatty alcohol solvents. The fatty alcohol solvents may be fatty alcohols or a blended solvent of fatty alcohols and water; the fatty alcohols may be C 1-10 Fatty alcohol, in this case, the fatty alcohol solvent is C 1-10 Fatty alcohol solvents can be C 1-10 Fatty alcohol or C 1-10 A mixed solvent of fatty alcohol and water. 1-10 The carbon number of the fatty alcohol can be 1 to 10, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10, and the carbon number of 1 corresponds to methanol, and the carbon number of 2 corresponds to ethanol. The fatty alcohol can include one or more of methanol and ethanol. The benzene solvent can be one or more of benzene and its alkyl substituents. Alkyl substituents of benzene include toluene, ethylbenzene, etc.

[0156] In some embodiments, the solvent used in the polymerization conditions is selected from C 1-10 One or more of aliphatic alcohol solvents and benzene solvents.

[0157] In some embodiments, the solvent used in the polymerization conditions is a fatty alcohol solvent, which can further be C1-10 Fatty alcohol solvents. Fatty alcohol solvents can also refer to the above definition. For example, the solvent used in the polymerization conditions can be C 1-10 Fatty alcohol or C 1-10 A blend of fatty alcohol and water. 1-10 The number of carbon atoms in the fatty alcohol is, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0158] In some embodiments, the alcohol solvent used in the polymerization conditions is ethanol, methanol or a water-alcohol mixture. Further, the alcohol in the water-alcohol mixture can be methanol, ethanol or a combination thereof.

[0159] In some embodiments, the solvent used in the polymerization conditions is ethanol.

[0160] In some embodiments, in step S140, reacting under polymerization conditions comprises: stirring and reacting at 60° C. to 80° C. for 10 h to 15 h in the presence of a solvent and a catalyst; wherein the solvent is selected from C 1-10 One or more of aliphatic alcohol solvents and benzene solvents, wherein the aliphatic alcohol solvent may be C 1-10 Fatty alcohol or C 1-10 A blended solvent of fatty alcohol and water, wherein the benzene solvent may be one or more of benzene and its alkyl substituents; further, the amount of the solvent may be 5 to 10 times the mass of the unsaturated reaction monomer; the mass percentage of the catalyst relative to the mass of the unsaturated reaction monomer may be 1% to 3%; further, the mass ratio of the coupling agent modified inorganic particles and the unsaturated reaction monomer is (0.1 to 0.2):1, at which time, the initial mass ratio of the coupling agent modified inorganic particles, the solvent, the unsaturated reaction monomer and the catalyst may be (0.1 to 0.2):(5 to 10):1:(1% to 3%). Further, the unsaturated reaction monomer is selected from one or more of alkyl acrylate and alkyl methacrylate. Further, the coupling agent modified inorganic particles are silane coupling agent modified silica particles.

[0161] In some embodiments, the preparation method meets one or more of the following characteristics:

[0162] The coupling agent modified inorganic particles are silane coupling agent modified silica particles; the silane coupling agent modified silica particles are prepared by a method comprising the following steps: mixing a mixed solution A1 in which silica particles are uniformly dispersed with an aqueous solution B1 containing a silane coupling agent, adjusting the pH value to be weakly acidic at 5.0 to 6.5, performing a silanization coupling reaction for 0.5 h to 3 h (optionally, performing a silanization coupling reaction under heating conditions in a water bath), separating by suction filtration, washing with water, washing with anhydrous ethanol, and drying at 60° C. to 120° C. for 3 h to 12 h to obtain silane coupling agent modified silica particles; wherein the solvent in the mixed solution A1 is a mixed solvent of water and ethanol at a mass ratio of (1 to 1.5):1;

[0163] The unsaturated reactive monomer is selected from one or more of alkyl acrylate and alkyl methacrylate (optionally, the unsaturated reactive monomer is one or more of methyl methacrylate and ethyl methacrylate);

[0164] The reaction under polymerization conditions comprises: stirring and reacting at 60°C to 80°C for 10h to 15h in the presence of a solvent and a catalyst; wherein the solvent is selected from C 1-10 One or more of aliphatic alcohol solvents and benzene solvents, wherein the aliphatic alcohol solvent is C 1-10 Fatty alcohol or C 1-10 A co-mixed solvent of fatty alcohol and water, wherein the benzene solvent is one or more of benzene and its alkyl substituents; the amount of the solvent is 5 to 10 times the mass of the unsaturated reaction monomer; the mass of the catalyst is 1% to 3% relative to the mass of the unsaturated reaction monomer.

[0165] After the reaction under the polymerization conditions is completed, the following post-treatment steps are further included: cooling, filtering, and drying. In some embodiments, cooling to room temperature can be performed using cooling water.

[0166] Polymer-coated inorganic particles

[0167] In some embodiments, the mass percentage of the polymer component in the polymer-coated inorganic particles is 80% to 98%, such as any of the following percentages: 80%, 82%, 84%, 85%, 86%, 88%, 90%, 92%, 94%, 95%, 96%, 98%, etc., and can also be selected from the interval consisting of any two of the above percentages. By adjusting the polymer component in the polymer-coated inorganic particles to have a more appropriate percentage, the dispersibility of the modified inorganic particles in the PTFE micropowder can be better adjusted.

[0168] In the present invention, the mass proportion of the polymer component in the polymer-coated inorganic particles can be tested by the following method: it can be obtained by converting the mass of the polymer-coated inorganic particles with the mass after removing the polymer, and the corresponding removal method can be selected according to the structural characteristics and properties of the polymer, the properties of the inorganic matter, etc., and it can be achieved by using chemical solvents, mechanical separation and other technologies; taking the unsaturated reaction monomer CH2=CH(R1)-C(=O)OR as an example, the polymerization product generated by the in-situ polymerization reaction is a chain structure, and the chain polymerization product can be soaked and washed with a corresponding solvent to remove it.

[0169] It is understood that the average particle size of the polymer-coated inorganic particles is larger than that of the corresponding inorganic particles. In some embodiments, the average particle size of the polymer-coated inorganic particles is 0.5 μm to 200 μm, for example 0.8 μm to 1.2 μm, 0.82 μm to 1.2 μm, etc.

[0170] In some embodiments, the preparation method meets one or more of the following characteristics:

[0171] The inorganic particles in the coupling agent-modified inorganic particles are selected from one or more of silicon dioxide, glass powder, aluminum oxide and titanium dioxide;

[0172] The average particle size of the inorganic particles in the coupling agent-modified inorganic particles is 0.1 μm to 200 μm;

[0173] The coupling agent in the coupling agent-modified inorganic particles is selected from one or more of silanes, phthalates and alkyls;

[0174] The unsaturated reactive monomer is selected from one or more of alkyl acrylate and alkyl methacrylate;

[0175] In the polymer-coated inorganic particles, the mass proportion of the polymer component is 80% to 98%;

[0176] The average particle size of the coupling agent modified inorganic particles is 0.1 μm to 200 μm.

[0177] In some embodiments, the preparation method meets one or more of the following characteristics:

[0178] The coupling agent modified inorganic particles are silane coupling agent modified silicon dioxide particles;

[0179] The unsaturated reactive monomer is one or more of methyl methacrylate and ethyl methacrylate.

[0180] S200: preparing a premix.

[0181] In step S200, PTFE micropowder, polymer-coated inorganic particles and auxiliary oil are mixed to prepare a premix.

[0182] In some embodiments, the mass ratio of the polymer-coated inorganic particles to the PTFE micropowder (as a percentage) is 0.1% to 3%, or can be any of the following percentages, or can be selected from the interval consisting of any two of the following percentages (as a percentage by weight): 0.1%, 0.2%, 0.3%, 0.4%, 0.5%, 0.6%, 0.8%, 1%, 1.2%, 1.5%, 1.6%, 1.8%, 2%, 2.2%, 2.4%, 2.5%, 2.6%, 2.8%, 3%, etc. For example, the mass ratio of the polymer-coated inorganic particles to the PTFE micropowder can also be selected from any of the following ranges: 0.1% to 0.5%, 0.1% to 0.8%, 0.1% to 0.6%, 0.3% to 0.6%, 0.4% to 0.6%, 0.5% to 1.5%, 0.8% to 1.2%, 1% to 2%, 2% to 3%, etc.

[0183] In some embodiments, the average particle size of the PTFE powder is 300 μm to 600 μm. The average particle size of the PTFE powder can also be selected from any one of the following particle sizes or from an interval consisting of any two of the following particle sizes: 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, 600 μm, etc. The PTFE powder used can be pre-sieved to obtain powder of a preset size.

[0184] In some embodiments, the auxiliary oil can be selected from auxiliary oils commonly used in the art. By adding auxiliary oil, the auxiliary oil and PTFE are fully infiltrated, and the materials can be mixed more evenly. Further, the auxiliary oil can be selected from one or more of Isopar H, Isopar G, aviation kerosene and naphtha.

[0185] In some embodiments, the percentage of the mass of the auxiliary oil relative to the sum of the masses of the PTFE micropowder and the polymer-coated inorganic particles is 14% to 25%, and can also be selected from any one of the following percentages or from the interval consisting of any two of the following percentages: 14%, 15%, 16%, 18%, 20%, 22%, 24%, 25%, etc., for example, 14% to 20%, etc. At this time, the ratio of the sum of the masses of the PTFE micropowder and the polymer-coated inorganic particles to the mass of the auxiliary oil can be adjusted to 50:7 to 5:1.

[0186] In some embodiments, mixing the PTFE micropowder, the polymer-coated inorganic particles and the auxiliary oil comprises: mixing the PTFE micropowder and the polymer-coated inorganic particles at high speed, adding the auxiliary oil for high-speed mixing; further, the speed of each high-speed mixing can be independently 800rpm to 1600rpm, for example, 800rpm, 1000rpm, 1200rpm, 1400rpm, 1500rpm, 1600rpm, etc.

[0187] In some embodiments, the time for each high-speed mixing may be 15 min to 45 min, for example, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, etc.

[0188] In some embodiments, mixing the PTFE micropowder, the polymer-coated inorganic particles and the auxiliary oil includes: mixing the PTFE micropowder and the polymer-coated inorganic particles at high speed for 15 minutes to 45 minutes, adding the auxiliary oil and mixing at high speed for 15 minutes to 45 minutes; further, the speed of each high-speed mixing can be independently 800rpm to 1600rpm, for example, 800rpm, 1000rpm, 1200rpm, 1400rpm, 1500rpm, 1600rpm, etc.

[0189] In some embodiments, the preparation method meets one or more of the following characteristics:

[0190] The average particle size of the PTFE powder is 300 μm to 600 μm;

[0191] The mass of the auxiliary oil is 14% to 25% of the sum of the mass of the PTFE micropowder and the polymer-coated inorganic particles;

[0192] Mixing the PTFE micropowder, the polymer-coated inorganic particles and the auxiliary oil comprises: mixing the PTFE micropowder and the polymer-coated inorganic particles at high speed for 15 minutes to 45 minutes, adding the auxiliary oil and mixing at high speed for 15 minutes to 45 minutes; wherein the speed of each high-speed mixing is independently 800 rpm to 1600 rpm;

[0193] The auxiliary oil is selected from one or more of Isopar H, Isopar G, aviation kerosene and naphtha.

[0194] S300: preparing a mixed material (powdered mixed material).

[0195] In step S300, the premix is ​​subjected to a aging treatment to obtain a mixed material. The purpose of aging is to allow the auxiliary oil to be fully dispersed and fully infiltrated with the PTFE, so that the materials are mixed more evenly. The mixed material is a powdery mixed material.

[0196] In some embodiments, the curing temperature does not exceed 37°C.

[0197] In some embodiments, the aging temperature is 22°C to 37°C, for example, 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, etc.; further, the aging time can be 12h to 48h, for example, 12h, 14h, 15h, 16h, 18h, 20h, 22h, 24h, 25h, 26h, 28h, 30h, 32h, 34h, 35h, 36h, 38h, 40h, 42h, 44h, 45h, 46h, 48h, etc.

[0198] In some embodiments, the conditions for performing the aging treatment include steps S310 and S320. In step S310, the temperature is 32°C to 37°C for 12h to 24h; and in step S320, the temperature is 22°C to 28°C for 12h to 24h. Using two temperature programs for staged aging treatment has the following advantages over a single temperature program: the oil can be fully dispersed and the powder can be fully matured.

[0199] S310: Treat at 32°C to 37°C for 12h to 24h. The aging temperature of this step can be 32°C to 37°C, such as 32°C, 33°C, 34°C, 35°C, 36°C, 37°C, etc. The aging time can be 12h to 24h, such as 12h, 14h, 15h, 16h, 18h, 20h, 22h, 24h, etc.

[0200] S320: Treat at 22°C to 28°C for 12h to 24h. The aging temperature of this step can be 22°C to 28°C, such as 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, etc. The aging time can be 12h to 24h, such as 12h, 14h, 15h, 16h, 18h, 20h, 22h, 24h, etc.

[0201] S400: Preforming and preparing blanks.

[0202] In step S400, the mixed material is preformed into a blank. For example, the mixed material can be preformed into a cylindrical blank.

[0203] Before the mixture is subjected to preforming treatment, the auxiliary oil is first removed to avoid explosion in the subsequent high temperature stage.

[0204] The mixture obtained after aging can be added to a preforming container, such as a barrel of a preforming machine, through an instrument with a sieve (such as a sieving funnel). By sieving, large pieces of tetrafluoroethylene powder that are not fully wetted by the oil can be removed.

[0205] In some embodiments, the mixed material is heated at 100°C to 250°C to remove the additive oil before the preforming process. Further, the heating temperature can be 120°C to 250°C, such as 120°C, 150°C, 160°C, 180°C, 200°C, 240°C, 250°C, etc.

[0206] In some embodiments, the conditions for performing the preforming treatment include: pressing at 20°C to 40°C (such as 20°C, 25°C, 30°C, 35°C, 40°C, etc.).

[0207] In some embodiments, the pressing speed is 200 mm / min to 350 mm / min, for example, 200 mm / min, 250 mm / min, 300 mm / min, 350 mm / min, etc.

[0208] In some embodiments, the conditions for performing the preforming treatment include: pressing at 20° C. to 40° C. with a pressing speed of 200 mm / min to 350 mm / min.

[0209] After the preforming process, the volume of the blank obtained by the preforming process shrinks relative to the volume of the mixed material obtained by aging. In some embodiments, the volume ratio of the mixed material to the blank can be (2-3):1, such as 2:1, 2.5:1, 3:1, etc.

[0210] In some embodiments, the volume ratio of the powdered mixture before pressing to the cylindrical blank obtained after compaction is (2-3):1, such as 2:1, 2.5:1, 3:1, etc.

[0211] In some embodiments, the compacted density of the blank is 1 g / cm 3 ~3g / cm 3 , for example 1g / cm 3 , 2g / cm 3 , 3g / cm 3 wait.

[0212] In some embodiments, the preforming process satisfies any one or both of the following conditions:

[0213] The volume ratio of the mixed material to the blank is (2-3):1;

[0214] The compacted density of the blank is 1 g / cm 3~3g / cm 3 .

[0215] In some embodiments, the blank is cylindrical.

[0216] S500: preparing a hollow raw material tube.

[0217] In step S500, the blank is subjected to paste extrusion to obtain a hollow raw tube. The hollow shape can be controlled by using a corresponding extrusion die.

[0218] The preformed blank can be placed in an extrusion container (such as a steel barrel of an extrusion device) and extruded into a hollow raw tube using a die suitable for the target formation. During the extrusion process, the single PTFE pellets in the preformed blank are greatly deformed by the die, forming continuous fibers that are connected together to form a tubular dense body, namely the raw tube.

[0219] In some embodiments, the conditions for the paste extrusion process include: at 40°C to 80°C (extrusion temperature), the extrusion speed is 1mm / min to 50mm / min, and the pulling speed is 1m / min to 10m / min. The ratio of the extrusion speed to the pulling speed can be 1:1 to 5:1, such as 1:1, 2:1, 3:1, 4:1, 5:1, etc. Examples of extrusion temperatures include 40°C, 50°C, 60°C, 70°C, 80°C, etc. Examples of extrusion speeds include 1m / min, 2m / min, 4m / min, 5m / min, 6m / min, 8m / min, 10m / min, 20m / min, 30m / min, 40m / min, 50m / min, etc. Examples of pulling speeds include 1m / min, 2m / min, 4m / min, 5m / min, 6m / min, 8m / min, 10m / min, 20m / min, 30m / min, 40m / min, 50m / min, etc.

[0220] In some embodiments, the inner diameter of the hollow raw material tube is 1 mm to 7 mm (eg, 1.00 mm to 7.00 mm).

[0221] In some embodiments, the single wall thickness of the hollow raw tube is 0.02 mm to 0.8 mm, and can further be 0.02 mm to 0.5 mm, such as 0.02 mm, 0.04 mm, 0.05 mm, 0.06 mm, 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, etc.

[0222] In some embodiments, the inner diameter of the hollow raw material tube is 1 mm to 7 mm (such as 1.00 mm to 7.00 mm), and the single wall thickness is 0.02 mm to 0.5 mm (it can also be other exemplary thicknesses listed herein).

[0223] S600: Preparation of PTFE tubing.

[0224] In step S600, the raw material tube is sintered to obtain a PTFE tube.

[0225] In some embodiments, the conditions for the sintering process include: sintering at 100°C to 490°C (sintering temperature) for 1 min to 10 min in an air atmosphere. Examples of sintering temperatures include 100°C, 120°C, 150°C, 200°C, 300°C, 400°C, 450°C, 490°C, and 120°C to 490°C. Examples of sintering temperatures include 1 min, 2 min, 4 min, 5 min, 6 min, 8 min, 10 min, and the like.

[0226] The size of PTFE pipes can be customized according to usage requirements, including but not limited to specifications such as inner diameter 3.0mm, inner diameter 4.0mm, and inner diameter 7.0mm.

[0227] In some embodiments, the inner diameter of the PTFE tube is 1 mm to 7 mm (eg, 1.00 mm to 7.00 mm).

[0228] In some embodiments, the single wall thickness of the PTFE tube is 0.02 mm to 0.8 mm, and can further be 0.02 mm to 0.5 mm, such as 0.02 mm, 0.04 mm, 0.05 mm, 0.06 mm, 0.08 mm, 0.1 mm, 0.12 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, 0.45 mm, 0.5 mm, etc.

[0229] In some embodiments, the inner diameter of the PTFE tube is 1 mm to 7 mm (eg, 1.00 mm to 7.00 mm), and the single wall thickness is 0.02 mm to 0.5 mm (other exemplary thicknesses listed herein may also be possible).

[0230] In some embodiments, after sintering, the tube may be cut to a desired length.

[0231] In some embodiments, the powdered mixture obtained by aging is added (slowly added) to the barrel of the preformer with a screening funnel, so that it is evenly dispersed in the barrel, and the material is compacted into a cylindrical blank at a preset speed. The blank obtained by the above preforming is then placed in a steel drum of an extrusion device, and a raw tube (hollow) is formed by extrusion using a mold corresponding to the extrusion shape. During the extrusion process, the material is extruded and formed at a certain extrusion speed under a certain traction speed. During the extrusion process, a single PTFE pellet in the preformed blank is greatly extruded and deformed after being extruded by the mold, forming continuous fibers, which are connected together to form a tubular dense body, which is a raw tube. After the raw tube obtained by extrusion is sintered, it is aged into a tube to obtain a PTFE tube. According to the different specifications of the raw tube and the target PTFE tube, matching process molds, extrusion speeds, traction speeds, sintering temperatures and other parameters can be selected.

[0232] In the preparation method, PTFE micropowder and polymer-coated inorganic particles are mixed, aged, preformed, paste-extruded and sintered to prepare a high-strength PTFE tube, wherein the polymer-coated inorganic particles include inorganic particles and olefin carboxylate polymers coated on the surface of the inorganic particles. The preparation method can be used to prepare a high-strength thin-walled PTFE inner tube.

[0233] The preparation method provided by the present invention can significantly improve the problems of poor wear resistance, insufficient strength, easy scratching, etc. of the PTFE tube in the traditional process.

[0234] The PTFE inner tube prepared by the above method has high precision, stable size, smooth surface, and good strength. The tube is not easy to be kinked and has good operation and use feeling.

[0235] The method mentioned in the present invention has simple process and can be used for continuous and large-scale production.

[0236] The PTFE pipe can also be prepared by one-step pasty extrusion molding. The paste extrusion molding method provided by the present invention has a simple manufacturing process and low cost. The molded pipe has high strength, high precision and good flexibility. The problem of easy wear and tear of the PTFE inner pipe in the traditional process is significantly improved.

[0237] In addition, the method for preparing a PTFE tube based on one-step molding by paste extrusion provided by the present invention can be applied to products of various specifications that can be produced by paste extrusion equipment.

[0238] In some embodiments, the prepared PTFE tube is a single-layer hollow tubular structure.

[0239] The PTFE tube provided by the present invention is mainly formed of PTFE material, has good tube strength, high temperature resistance, and stable chemical properties, and can be used as a developing tube.

[0240] In some embodiments, the PTFE tubing is prepared using a method comprising the following steps:

[0241] (1) Preparation of polymer-coated inorganic particles.

[0242] Add inorganic particles to the corresponding solvent, ultrasonically vibrate for 5min to 15min, and then magnetically stir for 0.5h to 1.5h to disperse the inorganic particles evenly in the solvent to obtain an inorganic particle suspension; add the coupling agent (refer to the definition above) to a container filled with distilled water, magnetically stir for 0.5h to 1.5h to fully hydrolyze it to obtain a coupling agent solution; mix the two prepared liquids, adjust the pH to a suitable value according to the reaction properties of the inorganic particles, and then pour the mixed solution into a container for heating and stirring in a water bath for reaction. After the reaction is completed, filter, wash, and dry. The powder of the coupling agent-modified inorganic particles is obtained.

[0243] Add the above-mentioned coupling agent modified inorganic particles, solvent, polymerization monomer and other raw materials in the container in sequence, and react for 10h to 24h under mechanical stirring and 60℃ to 180℃. After the in-situ polymerization reaction is completed, cool to room temperature with cold water, filter and dry to obtain polymer-coated inorganic particles.

[0244] (2) Mixing of raw materials.

[0245] After sieving the PTFE powder, mix it at high speed in a high-speed mixer for 1min to 5min. Add the above-mentioned powder of polymer-coated inorganic particles to the PTFE powder according to the preset ratio, put it in a high-speed mixer and mix it at high speed for 15min to 45min, so that the PTFE powder and the polymer-coated inorganic particle powder are evenly mixed. Add auxiliary oil to the above powder according to the preset ratio, put it in a high-speed mixer and mix it at high speed for 15min to 45min (the type of auxiliary oil can refer to the above definition). Place the above-mentioned mixed powder in a 35℃ oven for 12h to 24h, and then place it in a 25℃ environment for 12h to 24h to fully mature.

[0246] (3) Preforming.

[0247] Use a funnel with a screen to add the cooked powdered mixture into the barrel of the preforming machine, disperse it evenly in the barrel, and slowly compact the powder into a cylindrical blank at a preset speed.

[0248] (4) Paste extrusion.

[0249] The preformed blank is placed in a steel barrel of an extrusion device and extruded into a raw tube using a specific die. During the extrusion process, the individual PTFE pellets in the preformed blank are greatly deformed by the die, forming continuous fibers that are connected together to form a tubular dense body, which is the raw tube.

[0250] (5) Sintering the raw material tube prepared by paste extrusion to obtain a PTFE tube. This can be done in a sintering furnace.

[0251] The size of the granular material involved in the present invention can be measured by conventional particle size testing methods, including but not limited to: laser particle size analyzer, dynamic light scattering particle size analyzer, scanning electron microscope image observation, etc. The granular material can include but is not limited to: inorganic particles, coupling agent modified inorganic particles, polymer coated inorganic particles, PTFE micropowder and other particles or particle sizes in powder.

[0252] In a second aspect of the present invention, a PTFE inner tube is provided, which is prepared by the preparation method described in the first aspect of the present invention.

[0253] In the third aspect of the present invention, a pipe is provided, which includes the PTFE inner pipe described in the second aspect of the present invention. It is understood that in addition to the PTFE inner pipe, the pipe also includes an outer pipe in the radial direction of the center of the raw material pipe, and the outer pipe can be a single-layer or multi-layer structure. Among them, the outer pipe part in contact with the PTFE inner pipe can be made of polyethylene terephthalate (PET), nylon, polyimide and the like.

[0254] In the fourth aspect of the present invention, there is provided use of the PTFE inner tube described in the second aspect of the present invention or the tube described in the third aspect of the present invention in the preparation of medical tubes.

[0255] By way of non-limiting example, medical tubing may include catheters, drains, shunts, cannulas, ear tubes, and the like.

[0256] Some specific embodiments are provided below.

[0257] The embodiments of the present invention will be described in detail below in conjunction with examples. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. The experimental methods in the following examples that do not specify specific conditions are preferably referred to the guidance provided in the present invention, and can also be based on the experimental manual or normal conditions in this area, can also be based on the conditions recommended by the manufacturer, or refer to experimental methods known in the art.

[0258] In the following specific embodiments, the measured parameters of raw material components may have slight deviations within the range of weighing accuracy unless otherwise specified. For temperature and time parameters, acceptable deviations caused by instrument test accuracy or operation accuracy are allowed.

[0259] In the following examples, unless otherwise specified, "room temperature" is 20° C. to 30° C., such as 25° C. Unless otherwise specified, the speed of "high-speed mixing" is 800 rpm to 1600 rpm.

[0260] Unless otherwise specified, the raw materials used in the following examples are commercially available.

[0261] PTFE micropowder, the average particle size is in the range of 300μm to 600μm, about 380μm.

[0262] The average particle size of nano-silicon dioxide particles is in the range of 0.1 μm to 200 μm, which is about 800 nm (about 0.8 μm) or 150 μm.

[0263] In the following examples, the process control conditions for pipe size are the same.

[0264] Example 1.

[0265] (1) Preparation of amino-modified inorganic particles (aminosilanized silica) and polymer-coated inorganic particles (polymethyl methacrylate-coated silica)

[0266] S120:

[0267] Add nano-silicon dioxide particles (SiO2 particles, with an average particle size of about 800 nm) into a mixed solution of water and ethanol (mass ratio of 1:1 to 1.5:1) (the mass ratio of SiO2 to the solvent is 1:5 to 1:10), ultrasonically vibrate for 5 minutes to 15 minutes, and then magnetically stir for 0.5 hours to 1.5 hours to uniformly disperse the nano-silicon dioxide in the solution; obtain a mixed solution A;

[0268] Weigh γ-aminopropyltriethoxysilane (coupling agent APTES) and pour it into a container filled with distilled water (the volume ratio of coupling agent to water is 4:5 to 6:5), and stir it with magnetic force for 0.5h to 1.5h (stirring for 1h in this example) to fully hydrolyze the coupling agent; obtain mixed solution B;

[0269] Mix the prepared mixed solution A and mixed solution B in a volume ratio of 1:4, adjust the pH to a weakly acidic pH of 5.0-6.5 with acetic acid and sodium hydroxide, then pour the mixed solution into a container, heat in a water bath, stir and react for 0.5h-3h (2h in this case). Filter, wash with deionized water and anhydrous ethanol three times respectively, and dry in an oven at 60℃-120℃ for 3h-12h (100℃, 8h in this case). Aminosilane SiO2 nanoparticles are obtained.

[0270] S140: Add the dried aminosilane SiO2 nanoparticles treated as above, anhydrous ethanol (solvent), methyl methacrylate (unsaturated reaction monomer) and azobisisobutyronitrile (AIBN, catalyst) in a mass ratio of 1:50:10:0.1 to the container, and react for 10h to 15h (65°C, 12h in this example) under mechanical stirring at 60°C to 80°C. Cool to room temperature with cold water, filter, and dry at 100°C. Then filter with a Buchner funnel, wash with distilled water several times (3 times in this example), and dry at 100°C. The dried product is wrapped with filter paper and placed in a Soxhlet extractor, extracted with methanol for 8 hours (to remove residual monomers), dried at 50°C and vacuum dried for 24 hours, and then extracted with acetone for 48 hours (to remove uncoated homopolymers of methyl methacrylate). The product is vacuum dried to obtain polymer-coated silica powder (a polymer-coated inorganic particle of the present invention is polymethyl methacrylate (PMMA)-coated silica) with an average particle size of about 0.8 to 1.2 μm.

[0271] (2) Preparation and aging of premix

[0272] After sieving PTFE micropowder (average particle size of about 380 μm), mix it at high speed in a high-speed mixer for 1 to 5 minutes, add the polymer-coated silica powder prepared in step (1) to the PTFE micropowder, put it in a high-speed mixer and mix it at high speed for 15 to 45 minutes to make the PTFE micropowder and the polymer-coated silica powder evenly mixed to obtain a premix. The mass ratio of the polymer-coated silica powder to the PTFE micropowder is 0.1%.

[0273] Add auxiliary oil (mass ratio 50:7 to 5:1, 1:16% in this example) to the above premix, put it into a high-speed mixer and mix it at high speed for 15min to 45min. The auxiliary oil is Isopar H. Place the mixed powder in a 35℃ oven for 12h to 24h, and then place it in a 25℃ environment for 12h to 48h to fully mature. Obtain a mixed material.

[0274] (3) Preforming, paste extrusion, sintering

[0275] After the matured powdered mixture is screened, it is slowly added to the barrel of the preformer with a screening funnel to be evenly dispersed in the barrel. The material is slowly compacted into a cylindrical blank at 25°C to obtain a cylindrical blank (solid strip with a circular cross-sectional shape). The pressing speed is 200mm / min~350mm / min, and the volume ratio of the powdered mixture before pressing to the cylindrical blank obtained after compaction is (2~3):1; compaction density: 1g / cm 3 ~3g / cm 3 .

[0276] The preformed blank is placed in a steel drum of an extrusion device, and a preformed mold is used to extrude the preformed blank into a hollow raw tube. The extrusion parameters are: 70°C, extrusion speed 20mm / min, and pulling speed 2m / min. During the extrusion process, the single PTFE pellets in the preformed blank are greatly deformed by the die, forming continuous fibers, which are connected together to form a tubular dense body to obtain a hollow raw tube. The inner diameter is 4.0mm and the single wall thickness is 0.2mm.

[0277] The obtained hollow raw material tube is sintered in a sintering furnace and matured into a tube. The sintering parameters are: sintering at 430℃ for 5min, and the atmosphere is air. After the sintering is completed, it is cooled to room temperature to obtain a PTFE tube. The inner diameter is 4.0mm and the single wall thickness is 0.2mm.

[0278] Example 2 to Example 4. The method is basically the same as that of Example 1, except that the mass ratio of the polymer-coated silica powder to the PTFE powder is changed, and the mass ratios of Examples 2-4 are 0.5%, 1%, and 3%, respectively.

[0279] Example 5. A method substantially the same as that of Example 1 is used, except that the amount of polymer coating in the polymer-coated inorganic particles is different; in step (1) S140, the mass ratio of aminosilanized SiO2 nanoparticles:methyl methacrylate is 1:8, and the polymerization reaction is carried out at 60°C for 10 hours.

[0280] Step S140 is as follows: add the dried aminosilanized SiO2 nanoparticles treated as above, anhydrous ethanol (solvent), methyl methacrylate (unsaturated reaction monomer) and azobisisobutyronitrile (AIBN, catalyst) in a mass ratio of 1.25:50:10:0.1 to the container, and react for 10 hours under mechanical stirring and 60°C. Cool to room temperature with cold water, filter, and dry at 100°C. Then filter with a Buchner funnel, wash with distilled water 3 times and dry at 100°C. The dried product is wrapped with filter paper and placed in a Soxhlet extractor, extracted with methanol for 8 hours (to remove residual monomers), dried at 50°C and vacuum dried for 24 hours, and then extracted with acetone for 48 hours (to remove uncoated homopolymers of methyl methacrylate), and the product is vacuum dried to obtain polymer-coated silica powder.

[0281] In this example, the polymer mass proportion of the polymer-coated silica powder is 98%, as shown in Table 1.

[0282] Example 6. A method substantially the same as that of Example 1 is used, except that: the amount of polymer coating in the polymer-coated inorganic particles is different; in step (1) S140, the mass ratio of aminosilanized SiO2 nanoparticles:methyl methacrylate is 1:5, and the polymerization reaction is carried out at 60°C for 10 hours.

[0283] Step S140 is as follows: add the dried aminosilane SiO2 nanoparticles treated as above, anhydrous ethanol (solvent), methyl methacrylate (unsaturated reaction monomer) and azobisisobutyronitrile (AIBN, catalyst) in a mass ratio of 2:50:10:0.1 to the container, and react for 10 hours under mechanical stirring and 60°C. Cool to room temperature with cold water, filter, and dry at 100°C. Then filter with a Buchner funnel, wash with distilled water 3 times and dry at 100°C. The dried product is wrapped with filter paper and placed in a Soxhlet extractor, extracted with methanol for 8 hours (to remove residual monomers), dried at 50°C and vacuum dried for 24 hours, and then extracted with acetone for 48 hours (to remove uncoated homopolymers of methyl methacrylate), and the product is vacuum dried to obtain polymer-coated silica powder.

[0284] In this example, the polymer mass proportion of the polymer-coated silica powder is 82%, as shown in Table 1.

[0285] Example 7: The polymer-coated silica powder was prepared by using a method substantially the same as that of Example 1, except that APTES (with amino groups) was replaced with propyltriethoxysilane without amino groups. The remaining steps were the same as those of Example 1.

[0286] Comparative Examples 1-3.

[0287] The method is basically the same as that of Example 1, except that in step (2), the mass ratio of the polymer-coated inorganic particles (polymer-coated silica) to the PTFE micropowder is 0%, 5%, and 10%, respectively.

[0288] Comparative Examples 4-5.

[0289] The method is basically the same as that in Example 3, except that the polymer coating step is omitted. That is, aminosilanized SiO2 nanoparticles are directly used as inorganic fillers for step (2), and the mass ratio of aminosilanized SiO2 nanoparticles to PTFE micropowder is 0.1% and 1%.

[0290] Comparative Examples 6-7.

[0291] The method is basically the same as that in Example 3, except that unmodified SiO2 nanoparticles are directly used as inorganic fillers in step (2), and the mass ratio of SiO2 nanoparticles to PTFE micropowder is 0.1% and 1%.

[0292] Comparative Example 8.

[0293] A method substantially the same as that in Example 3 is adopted, except that: in step (1), the step of treating the inorganic particles with a silane coupling agent is omitted, that is, in step S140, SiO2 is directly used instead of amino-silanized SiO2 nanoparticles; in step (2), the in-situ polymerized silica powder prepared in step (1) is used instead of the polymer-coated silica powder to be mixed with the PTFE micropowder.

[0294] (1) Step S140: SiO2 nanoparticles (average particle size of about 0.8 μm) not treated with a silane coupling agent, anhydrous ethanol (solvent), methyl methacrylate (unsaturated reaction monomer) and azobisisobutyronitrile (AIBN, catalyst) are added to the container in a mass ratio of 1:50:10:0.1, and reacted for 10 hours under mechanical stirring and 60°C. Cool to room temperature with cold water, filter, and dry at 100°C. Then filter with a Buchner funnel, wash with distilled water three times, and dry at 100°C. The dried product is wrapped with filter paper and placed in a Soxhlet extractor, extracted with methanol for 8 hours, dried at 50°C, and vacuum dried for 24 hours, then extracted with acetone for 48 hours, and the product is vacuum dried to obtain silica powder after in-situ polymerization.

[0295] (2) Preparation and aging of premix

[0296] After sieving PTFE micropowder (average particle size of about 380 μm), mix it at high speed in a high-speed mixer for 1 to 5 minutes, add the silica powder prepared in step (1) after in-situ polymerization to the PTFE micropowder, put it in a high-speed mixer and mix it at high speed for 15 to 45 minutes to make the PTFE micropowder and the polymer-coated silica powder evenly mixed to obtain a premix. The mass ratio of the polymer-coated silica powder to the PTFE micropowder is 0.1%.

[0297] Add auxiliary oil to the premix (the mass ratio of auxiliary oil to premix is ​​16%), put it into a high-speed mixer and mix it at high speed for 15min to 45min. The auxiliary oil is Isopar H. Place the mixed powder in a 35℃ oven for 12h to 24h, and then place it in a 25℃ environment for 12h to 48h to fully mature. Obtain a mixture.

[0298] (3) Using the mixture prepared in step (2), a PTFE tube is prepared by the method of step (3) in Example 3.

[0299] Comparative Example 9.

[0300] The method is substantially the same as that of Example 1, except that the monomer is first prepared by solvent polymerization and then mixed with the coupling agent-modified inorganic particles.

[0301] (1) Aminosilane-containing SiO2 nanoparticles were prepared using the method of step (1) in Example 1.

[0302] (2) Add anhydrous ethanol, methyl methacrylate monomer and azobisisobutyronitrile in a mass ratio of 100:10:1 to the container, react for 12 hours under mechanical stirring at 65°C, and cool to room temperature with cold water; then add the dried aminosilanized SiO2 nanoparticles prepared in step (1), mix at high speed for 30 minutes; filter, and dry at 100°C. Then filter with a Buchner funnel, wash with distilled water three times, and dry at 100°C. The dried product is wrapped with filter paper and placed in a Soxhlet extractor, extracted with methanol for 8 hours (to remove residual monomers), dried at 50°C, and vacuum dried for 24 hours to obtain a polymer-inorganic composite filler.

[0303] (3) The polymer-inorganic composite filler prepared in step (2) is used to replace the powdery mixed material in Example 1, and a PTFE tube is prepared according to the method of step (3) in Example 1.

[0304] Comparative Example 10.

[0305] A method substantially the same as that in Example 1 is used, except that the unsaturated reaction monomer is replaced by methacrylic acid (olefinic carboxylic acid), and the remaining operation steps are the same as those in Example 1.

[0306] The parameters of Examples 1 to 7 and Comparative Examples 1 to 10 can be found in Table 1.

[0307] Table 1.

[0308]

[0309]

[0310] In Table 1, the coupling agent modified inorganic particles in Examples 1 to 5 are APTES modified SiO2, the average particle size of the silica raw material in Examples 1 to 4 is about 0.8 μm, and the average particle size of the silica raw material in Example 5 is about 150 μm; Methyl methacrylate monomer is used in Examples 1-7, Comparative Examples 1-3, and Comparative Examples 6-9, and methacrylic acid monomer is used in Comparative Example 10.

[0311] Test analysis method:

[0312] 1. Test and analysis method for the mass proportion of polymer in polymer-coated inorganic particles: Calculated based on the weight W0 of the inorganic particles before coating and the weight W1 after coating, the mass proportion of polymer = (W1-W0) / W1×100%.

[0313] 2. Mechanical properties test

[0314] 2.1. Young's modulus and tensile properties (tensile stress, maximum tensile force, elongation at break)

[0315] Instrument: The test is carried out using a universal material mechanical testing machine.

[0316] Sample preparation method: Length 100-150 mm. The sample length used for each test sample in Table 2.

[0317] Test mode: tensile mode, 25℃. When testing Young's modulus, a certain tensile force is used, the corresponding deformation is recorded, and the Young's modulus is calculated according to the stress-strain relationship. When testing tensile properties, a certain tensile speed is used until the tensile fracture occurs, and the corresponding tensile stress, tensile force, and sample length at fracture are recorded, and the tensile stress and elongation at fracture are calculated.

[0318] The corresponding samples to be tested in Table 2 are tested under the same tensile force or tensile speed.

[0319] 2.2. Wear resistance (wear volume) and friction performance (friction coefficient)

[0320] Instrument: Friction and wear performance testing machine (Anton Paar TRB pin-on-disk friction testing machine).

[0321] The smaller the friction coefficient, the lower the surface roughness of the sample and the smoother it is.

[0322] When simulating friction a certain number of times under a certain friction force, the greater the amount of wear produced, the worse the wear resistance. Conversely, the lower the amount of wear, the better the wear resistance.

[0323] The test results can be found in Table 2.

[0324] Result analysis:

[0325] The PTFE tubes prepared in Examples 1 to 7 are all thin-walled PTFE tubes, with a single wall thickness in the range of 0.02 mm to 0.8 mm, and further in the range of 0.02 mm to 0.5 mm, and the inner diameter of the PTFE tubes in the range of 1 mm to 7 mm. The prepared PTFE tubes have high strength characteristics and excellent tensile properties while maintaining the advantages of low friction coefficient and low wear. Moreover, very high strength and excellent tensile properties can be obtained under the condition of thin walls and excellent friction resistance of PTFE materials.

[0326] In Comparative Example 1, no polymer-coated inorganic particles were added, and the Young's modulus was inferior to that of Examples 1-7 of the present application. In Comparative Example 3, the content of polymer-coated inorganic particles was too high, which not only resulted in Young's modulus and tensile properties being inferior to those of Examples 1-4 of the present application (using polymer-coated inorganic particles with the same polymer coating amount), but also resulted in a significant increase in the friction coefficient. Compared with Examples 1-4 (using polymer-coated inorganic particles with the same polymer coating amount), the Young's modulus in Comparative Example 2 decreased, and the wear resistance also decreased to a certain extent.

[0327] Compared with Example 3, the inorganic particles in Comparative Example 5 were not polymer coated, and the Young's modulus and tensile properties were significantly reduced, and the wear amount and friction coefficient were significantly increased. Similarly, compared with Examples 1 to 3, the inorganic particles in Comparative Example 4 were not polymer coated, and the Young's modulus and tensile properties were significantly reduced, and the wear amount and friction coefficient were significantly increased.

[0328] Compared with Example 3, the inorganic particles in 7 were not modified, neither the coupling agent modification treatment nor the polymer coating was performed, and the Young's modulus and tensile properties also decreased significantly, and the wear amount and friction coefficient increased significantly. Similarly, compared with Example 1, the inorganic particles in 6 were not modified, neither the coupling agent modification treatment nor the polymer coating was performed, and the Young's modulus and tensile properties also decreased significantly, and the wear amount and friction coefficient increased significantly.

[0329] Compared with Example 3, Comparative Example 8 omits the step of treating the inorganic particles with a coupling agent, and directly coats the inorganic particles that have not been treated with a coupling agent with a polymer. The Young's modulus and tensile properties are significantly reduced, and the friction coefficient is also significantly increased.

[0330] Compared with Example 1, in Comparative Example 9, the in-situ polymerization method was not used, but the polymer was first prepared and then blended with the coupling agent-modified inorganic particles. The Young's modulus and tensile properties also decreased significantly. In addition, the wear amount and friction coefficient also increased.

[0331] Compared with Example 1, in Comparative Example 10, the unsaturated reaction monomer is not olefinic carboxylic acid ester but olefinic carboxylic acid (methacrylic acid), and the Young's modulus and tensile properties are also significantly reduced.

[0332] Table 2.

[0333]

[0334]

[0335] The technical features of the above-mentioned embodiments and examples can be combined in any appropriate manner. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments and examples are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0336] The above embodiments only express several implementation methods of the present invention, which is convenient for understanding the technical solution of the present invention in detail, but it cannot be understood as limiting the scope of protection of the present invention. It should be pointed out that for ordinary technicians in this field, without departing from the concept of the present invention, several variations and improvements can be made, which all belong to the protection scope of the present invention. In addition, it should be understood that after reading the above teaching content of the present invention, those skilled in the art can make various changes or modifications to the present invention, and the equivalent forms obtained also fall within the protection scope of the present invention. It should also be understood that the technical solutions obtained by those skilled in the art on the basis of the technical solution provided by the present invention through logical analysis, reasoning or limited experiments are all within the protection scope of the claims attached to the present invention. Therefore, the protection scope of the patent of the present invention shall be based on the content of the attached claims, and the description and drawings can be used to explain the content of the claims.

Claims

1. A method for preparing a PTFE tube, characterized in that: The steps include: The coupling agent-modified inorganic particles and the unsaturated reaction monomer are mixed in a mass ratio of (0.1-0.2):1, and reacted under polymerization conditions to prepare polymer-coated inorganic particles; wherein the unsaturated reaction monomer is an olefin carboxylate containing a reactive carbon-carbon double bond; The PTFE powder, the polymer-coated inorganic particles and the auxiliary oil are mixed to prepare a premix; wherein the mass ratio of the polymer-coated inorganic particles to the PTFE powder is 0.1% to 3%; The premix is ​​subjected to a aging treatment to obtain a mixed material; Preforming the mixed material into a blank; Extruding the blank into a paste to obtain a hollow raw tube; The raw material tube is sintered to obtain a PTFE tube.

2. The preparation method according to claim 1, characterized in that: The single wall thickness of the PTFE tube is 0.02 mm to 0.8 mm.

3. The preparation method according to claim 2, characterized in that: Satisfy one or more of the following characteristics: The inner diameter of the hollow raw material tube is 1 mm to 7 mm; The single wall thickness of the hollow raw material tube is 0.02 mm to 0.5 mm; The inner diameter of the PTFE tube is 1 mm to 7 mm; The single wall thickness of the PTFE tube is 0.02 mm to 0.5 mm; The blank is cylindrical, and the PTFE tube is a hollow circular tube.

4. The preparation method according to claim 1, characterized in that: Satisfy one or more of the following characteristics: The inorganic particles in the coupling agent-modified inorganic particles are selected from one or more of silicon dioxide, glass powder, aluminum oxide and titanium dioxide; The average particle size of the inorganic particles in the coupling agent-modified inorganic particles is 0.1 μm to 200 μm; The coupling agent in the coupling agent-modified inorganic particles is selected from one or more of silanes, phthalates and alkyls; The unsaturated reactive monomer is selected from one or more of alkyl acrylate and alkyl methacrylate; In the polymer-coated inorganic particles, the mass proportion of the polymer component is 80% to 98%; The average particle size of the coupling agent modified inorganic particles is 0.1 μm to 200 μm; The average particle size of the PTFE micropowder is 300 μm to 600 μm.

5. The preparation method according to claim 4, characterized in that: Satisfy one or more of the following characteristics: The coupling agent modified inorganic particles are silane coupling agent modified silicon dioxide particles; The unsaturated reactive monomer is one or more of methyl methacrylate and ethyl methacrylate.

6. The preparation method according to any one of claims 1 to 5, characterized in that The coupling agent in the coupling agent-modified inorganic particles is an amino silane coupling agent.

7. The preparation method according to any one of claims 1 to 5, characterized in that Satisfy one or more of the following characteristics: The reaction under polymerization conditions includes: carrying out polymerization reaction at 60° C. to 180° C. for 10 h to 24 h in the presence of a solvent and a catalyst; After the reaction under polymerization conditions is completed, the following post-processing steps are also included: cooling, filtering, and drying; The mass of the auxiliary oil is 14% to 25% of the sum of the mass of the PTFE micropowder and the polymer-coated inorganic particles; Mixing the PTFE micropowder, the polymer-coated inorganic particles and the auxiliary oil comprises: mixing the PTFE micropowder and the polymer-coated inorganic particles at high speed for 15 minutes to 45 minutes, adding the auxiliary oil and mixing at high speed for 15 minutes to 45 minutes; wherein the speed of each high-speed mixing is independently 800 rpm to 1600 rpm; The auxiliary oil is selected from one or more of Isopar H, Isopar G, aviation kerosene and naphtha; The conditions for the aging treatment include: treating at 32°C to 37°C for 12h to 24h, treating at 22°C to 28°C for 12h to 24h Before the mixed material is subjected to preforming treatment, the auxiliary oil is firstly removed by heating at 100° C. to 250° C.; The conditions for performing the preforming treatment include: pressing at 20°C to 40°C with a pressing speed of 200mm / min to 350mm / min; The volume ratio of the mixed material to the blank is (2-3):1; The compacted density of the blank is 1 g / cm 3 ~3g / cm 3 ; The conditions for the paste extrusion treatment include: at 40°C to 80°C, an extrusion speed of 1mm / min to 50mm / min, and a pulling speed of 1m / min to 10m / min; The conditions for the sintering treatment include: sintering at 100° C. to 490° C. for 1 min to 10 min in an air atmosphere.

8. The preparation method according to claim 7, characterized in that: Satisfy one or more of the following characteristics: The coupling agent modified inorganic particles are silane coupling agent modified silica particles; the silane coupling agent modified silica particles are prepared by a method comprising the following steps: mixing a mixed solution A1 in which silica particles are uniformly dispersed with an aqueous solution B1 containing a silane coupling agent, adjusting the pH value to be weakly acidic at 5.0 to 6.5, performing a silylation coupling reaction for 0.5 to 3 hours, filtering and separating, washing with water, washing with anhydrous ethanol, and drying at 60° C. to 120° C. for 3 to 12 hours to obtain silane coupling agent modified silica particles; wherein the solvent in the mixed solution A1 is a mixed solvent of water and ethanol at a mass ratio of (1 to 1.5):1; The unsaturated reactive monomer is selected from one or more of alkyl acrylate and alkyl methacrylate; The reaction under polymerization conditions comprises: stirring and reacting at 60°C to 80°C for 10h to 15h in the presence of a solvent and a catalyst; wherein the solvent is selected from C 1-10 One or more of aliphatic alcohol solvents and benzene solvents, wherein the aliphatic alcohol solvent is C 1-10 Fatty alcohol or C 1-10 A co-mixed solvent of fatty alcohol and water, wherein the benzene solvent is one or more of benzene and its alkyl substituents; the amount of the solvent is 5 to 10 times the mass of the unsaturated reaction monomer; the mass of the catalyst is 1% to 3% relative to the mass of the unsaturated reaction monomer.

9. A PTFE inner tube, characterized in that: The method is prepared according to any one of claims 1 to 8.

10. A pipe, characterized in that: Comprising the PTFE inner tube as claimed in claim 9.

11. Use of the PTFE inner tube according to claim 9 or the tube according to claim 10 in the preparation of medical tubes.

Images