A polypropylene pipe with a biomimetic structure for biomedical use and a preparation method thereof

Abstract

The present invention provides a polypropylene pipe with a biomimetic structure for biomedical use and a preparation method thereof. The method is to melt and extrude a blend of syndiotactic polypropylene and isotactic polypropylene in a specific ratio to form a pipe blank, and then prepare an open-cell porous polypropylene pipe through selective chemical etching of cyclohexane under specific conditions. The prepared pipe has a microporous structure feature with interconnected pores inside its pipe wall, and is extremely suitable for application as a biomedical material.

Description

[0001] This application is a divisional application, the original application number is: 202210893082.1, the application date is July 27, 2022, and the name of the invention is: A chemically etched open-hole porous polypropylene pipe and its preparation method. Technical Field

[0002] The invention relates to the technical field of polypropylene pipes, and in particular to a chemically etched open-hole porous polypropylene pipe and a preparation method thereof. Background Art

[0003] Since the discovery of stereoselective olefin polymerization in 1954, people have entered a new era of polyolefin synthesis. Thanks to this, polypropylene (PP) has been industrially produced and applied on a large scale since 1957, and related research has been continuously carried out and deepened, which has made polypropylene products enduring. Generally speaking, polypropylene products are processed in a variety of ways, including injection molding, extrusion, etc., so that they can be processed into products of various forms and uses. Among them, various spare parts, pipes, plastic woven products, film products, etc. prepared from polypropylene have been extremely widely used. At present, polypropylene has become the second largest polymer material in the world. In addition, as a multi-purpose polymer material, polypropylene has attracted the attention of many researchers with its special crystallization, controlled polymerization of polyolefins, and the influence of processing conditions on polymorphic structures.

[0004] Although both syndiotactic polypropylene (sPP) and isotactic polypropylene (iPP) are polypropylene materials, their performance is different due to their different structures. Compared with iPP, the molecular chain flexibility of sPP is poor and it is relatively less likely to crystallize, which also leads to many differences in performance. This difference directly leads to the melting point, glass transition temperature, crystallization temperature and crystallinity of sPP being lower than iPP. Compared with iPP products, sPP products have higher transparency, impact resistance, toughness and elasticity. However, the density, hardness, tensile strength and rigidity of sPP are lower than those of iPP. Moreover, with the increase of the degree of polymerization and syndiotacticity of sPP, the melting point and crystallization temperature of sPP are improved.

[0005] In the literature, the study of sPP and iPP blends found that iPP / sPP blends are phase separated. The evaluation found that the Flory-Huggins interaction parameter of the sPP / iPP mixture is almost zero, indicating that the interaction in the mixture is very weak. From this, the researchers proposed a mixture state close to phase separation, or in other words, the iPP / sPP mixture is immiscible. For the iPP-based blend, sPP is dispersed in the iPP matrix in an island structure.

[0006] Polypropylene pipes have excellent comprehensive properties, such as low thermal conductivity, high temperature resistance, corrosion resistance, and can be hot melt welded, etc., and are widely used in the fields of cold and hot water transportation in buildings. However, currently in the biomedical field, there is a need for a porous pipe for biomedical use, which needs to have a bionic structure similar to blood vessels, that is, the pipe wall has an open pore structure for cell adsorption, and there are connected micropores inside the pipe wall for cell metabolism. Obviously, the currently uniformly dense polypropylene pipes cannot meet such requirements. Summary of the Invention

[0007] According to the problems proposed by the above-mentioned prior art, the present invention provides a chemically etched porous polypropylene pipe and a preparation method thereof. The method is to select a blend of syndiotactic polypropylene and isotactic polypropylene in a specific ratio and melt-spin extrude it into a pipe blank, and then prepare a porous polypropylene pipe with open pores through selective chemical etching of cyclohexane under specific conditions. The prepared pipe has a microporous structure feature of interconnected inside its pipe wall, and is extremely suitable for application as a biomedical material.

[0008] To achieve the above object, the present invention is realized by a technical solution composed of the following technical measures.

[0009] On the one hand, the present invention provides a preparation method of a chemically etched porous polypropylene pipe, mainly including the following steps:

[0010] (1) Select syndiotactic polypropylene (sPP) and isotactic polypropylene (iPP), mix them in a mass ratio of (18 - 22):(78 - 82) or (38 - 42):(58 - 62) for standby, as the mixture.

[0011] (2) Extrude the mixture in step (1) through a rotary extruder, melt-spin extrude it into a pipe blank, and then cool and size it to obtain a polypropylene pipe; wherein, the rotary extruder includes a rotatable extrusion end component.

[0012] (3) Immerse the polypropylene pipe obtained in step (2) in cyclohexane, and prepare a porous polypropylene pipe with open pores through selective chemical etching of cyclohexane.

[0013] The main principle of the present invention is based on the accidental discovery of the inventor. Based on the blend composed of sPP and iPP, cyclohexane can selectively dissolve sPP under certain conditions. However, in the iPP / sPP mixture material mainly composed of iPP, sPP is dispersed in the iPP matrix in an island structure. By chemically etching sPP in it, only the sPP on the surface of the material can be dissolved, and the inside of the material still shows the characterization of iPP / sPP blend.

[0014] Through further research and exploration by the inventors, it was found that at a specific iPP / sPP blend ratio, through the extrusion-end rotation function of a rotary extruder and then via the selective chemical etching of cyclohexane, it is possible to etch into the inner wall of the pipe to present a porous characteristic consistent with the outer surface, and the holes formed by the etching also have a structurally interconnected feature due to the action of the extrusion-end rotation. This property can meet various requirements of such pipes in practical applications. For example, in the field of biomedical materials, cells can adsorb on the open-hole structure of the pipe wall, and there are interconnected micropores inside the pipe wall for cell metabolism.

[0015] In this article, the "syndiotactic polypropylene (sPP)" described in step (1) is a conventional syndiotactic polypropylene in the art, which can be of commercial origin or self-made.

[0016] In this article, the "isotactic polypropylene (iPP)" described in step (1) is a conventional isotactic polypropylene in the art, which can be of commercial origin or self-made.

[0017] In one embodiment, the raw material forms of the syndiotactic polypropylene (sPP) and isotactic polypropylene (iPP) described in step (1) can include, but are not limited to, powder and pellet forms, and can also be determined according to the applicable raw material forms of the rotary extruder used in step (2). When mixing and preparing for use, it can also include pretreatment processes or other technical means recorded in the prior art applicable to the polypropylene pipe process, such as washing and drying. However, it should be noted that the selection of the above embodiments should not affect the mass ratio of sPP and iPP.

[0018] In this article, the "rotary extruder" described in step (2) is an extruder with a rotatable extrusion end and suitable for pipe preparation. In one embodiment, the extrusion-end rotation can be a rotatable die, a rotatable mandrel, or both a rotatable die and a rotatable mandrel. It should be noted that the die can also be referred to as the head of the extruder, that is, the extrusion-end rotation is achieved through the rotation of the head.

[0019] In a preferred embodiment, the "rotary extruder" described in step (2) is the patented device "A Device for Preparing High-Performance Polymer Pipes" (CN101337425B) independently developed by the applicant of the present invention. Further, for the molten rotary extrusion of the pipe blank, the rotation modes include any one of the die rotating alone, the mandrel rotating alone, the die and the mandrel rotating in the same direction, and the die and the mandrel rotating in the opposite direction.

[0020] In one embodiment, for the "melt rotary extrusion tube blank" described in step (2), the rotation rate at the extrusion end is 10 - 40 rpm. Below this rotation rate, the holes inside the etched tube wall cannot be connected, while above this rotation rate, the molten tube blank is likely to break during the rotary extrusion process, and the product cannot be obtained.

[0021] In one embodiment, for the "melt rotary extrusion tube blank" described in step (2), except for the rotation rate at the extrusion end, the specific process parameters can refer to the existing technologies in the art or the specific processing parameters of the selected syndiotactic polypropylene (sPP) and isotactic polypropylene (iPP), such as the melt temperature window data of commercially available isotactic polypropylene.

[0022] In one embodiment, the "cooling and sizing" described in step (2) is a conventional process method in the field of pipe preparation. For example, the tube blank is cooled and sized through a vacuum sizing and cooling device.

[0023] In a preferred embodiment, the selective chemical etching with cyclohexane described in step (3) is carried out at a temperature of 40 - 60 °C for 30 - 90 minutes.

[0024] On the other hand, the present invention provides an open-cell porous polypropylene pipe obtained by the above preparation method.

[0025] On the other hand, the present invention provides the application of the above open-cell porous polypropylene pipe in the biomedical field.

[0026] The present invention has the following beneficial effects:

[0027] 1. The preparation method of the present invention utilizes the selective chemical etching of cyclohexane on syndiotactic polypropylene, which is accidentally discovered, and cooperates with melt rotary extrusion to successfully prepare a polypropylene pipe with open cells and a microporous structure feature of interconnected pores inside the tube wall.

[0028] 2. The present invention verifies through actual experiments the conditions necessary for the microporous structure feature of interconnected pores inside the tube wall of the product, and finds that this feature is present only under a specific iPP / sPP blend ratio.

[0029] 3. Through the comparative analysis of SEM images obtained from a large number of experiments, the present invention finds that the higher the rotation rate during the preparation process, the more obvious the interconnected holes inside the tube wall; and based on the evaluation of the obviousness of the interconnected holes inside the tube wall, reverse rotation of the die and mandrel > co-rotation of the die and mandrel > single rotation of the mandrel ≈ single rotation of the die.

[0030] 4. The preparation process of the present invention is relatively simple and easy to implement. The prepared product is extremely suitable for the requirements of porous pipes for biomedical use and has a bionic structure similar to blood vessels, that is, the pipe wall has an open-hole structure for cell adsorption, and there are also connected micropores inside the pipe wall for cell metabolism.

[0031] Explanatory drawings of the specification

[0032] Figure 1 This is the SEM image after cutting of the open-hole porous polypropylene pipe prepared in Example 6 of the present invention with a rotation rate set at 40 rpm. It can be clearly observed from the figure that there are connected holes inside the pipe wall.

[0033] Figure 2 This is the SEM image after cutting of the open-hole porous polypropylene pipe prepared in Example 6 of the present invention with a rotation rate set at 30 rpm. It can be clearly observed from the figure that there are connected holes inside the pipe wall.

[0034] Figure 3 This is the SEM image after cutting of the open-hole porous polypropylene pipe prepared in Example 6 of the present invention with a rotation rate set at 20 rpm. It can be relatively clearly observed from the figure that there are connected holes inside the pipe wall.

[0035] Figure 4 This is the SEM image after cutting of the open-hole porous polypropylene pipe prepared in Example 6 of the present invention with a rotation rate set at 10 rpm. It can be relatively clearly observed from the figure that there are connected holes inside the pipe wall.

[0036] Figure 5 This is the SEM image after cutting of the open-hole porous polypropylene pipe prepared in Example 5 of the present invention with a rotation rate set at 40 rpm. It can be clearly observed from the figure that there are connected holes inside the pipe wall.

[0037] Figure 6 This is the SEM image after cutting of the open-hole porous polypropylene pipe prepared in Example 5 of the present invention with a rotation rate set at 30 rpm. It can be clearly observed from the figure that there are connected holes inside the pipe wall.

[0038] Figure 7 This is the SEM image after cutting of the open-hole porous polypropylene pipe prepared in Example 5 of the present invention with a rotation rate set at 20 rpm. It can be relatively clearly observed from the figure that there are connected holes inside the pipe wall.

[0039] Figure 8 This is the SEM image after cutting of the open-hole porous polypropylene pipe prepared in Example 5 of the present invention with a rotation rate set at 10 rpm. It can be relatively clearly observed from the figure that there are connected holes inside the pipe wall.

[0040] Figure 9This is the SEM image after cutting of the open-cell porous polypropylene pipe prepared in Example 4 of the present invention with a rotation rate set at 40 rpm. It can be clearly observed from the figure that there are connected holes inside the pipe wall.

[0041] Figure 10 This is the SEM image after cutting of the open-cell porous polypropylene pipe prepared in Example 4 of the present invention with a rotation rate set at 30 rpm. It can be clearly observed from the figure that there are connected holes inside the pipe wall.

[0042] Figure 11 This is the SEM image after cutting of the open-cell porous polypropylene pipe prepared in Example 4 of the present invention with a rotation rate set at 20 rpm. It can be relatively clearly observed from the figure that there are connected holes inside the pipe wall.

[0043] Figure 12 This is the SEM image after cutting of the open-cell porous polypropylene pipe prepared in Example 4 of the present invention with a rotation rate set at 10 rpm. It can be relatively clearly observed from the figure that there are connected holes inside the pipe wall.

[0044] Figure 13 This is the SEM image after cutting of the open-cell porous polypropylene pipe prepared in Example 2 of the present invention from another angle. It can be extremely clearly observed from the figure that there are holes inside the pipe wall.

[0045] Figure 14 This is the SEM image after cutting of the polypropylene pipe prepared in Comparative Example 1 of the present invention. It can be found from the figure that there are no holes inside the pipe wall. The SEM characterizations of Comparative Example 2 and the polypropylene pipe prepared by the direct extrusion method without rotational extrusion are consistent with this. Detailed Description of the Invention

[0046] To further understand the present invention, the preferred embodiments of the present invention will be described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the invention. Those skilled in the art can draw on the content of this article and appropriately modify the process parameters to achieve. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art, and they are all considered to be included in the present invention. The methods and applications of the present invention have been described through preferred examples, and those skilled in the art can obviously make changes or appropriate alterations and combinations to the methods and applications described herein without departing from the content, spirit and scope of the present invention to implement and apply the technology of the present invention. Although it is believed that those of ordinary skill in the art are fully aware of the following terms, the following definitions are still presented to help illustrate the subject matter disclosed by the present invention.

[0047] As used herein, the term "comprising" is synonymous with "primarily comprising", and is inclusive or open-ended, and does not exclude additional unrecited elements or method steps. "Containing" is a technical term used in claim language, meaning that the stated elements exist, but other elements may also be added and still form elements or methods within the scope of the claim.

[0048] The present invention provides a method for preparing a chemically etched open-cell porous polypropylene pipe, mainly comprising the following steps:

[0049] (1) Select syndiotactic polypropylene (sPP) and isotactic polypropylene (iPP), mix them according to a mass ratio of (18 - 22):(78 - 82) or (38 - 42):(58 - 62) for standby as a mixture.

[0050] (2) Extrude the mixture in step (1) through a rotary extruder to melt and rotationally extrude a pipe blank, and then obtain a polypropylene pipe through cooling and sizing; wherein, the rotary extruder includes a rotatable extrusion end component.

[0051] (3) Immerse the polypropylene pipe obtained in step (2) in cyclohexane, and prepare an open-cell porous polypropylene pipe through selective chemical etching of cyclohexane.

[0052] In this article, the "syndiotactic polypropylene (sPP)" described in step (1) is a conventional syndiotactic polypropylene in the art, which can be of commercial origin or prepared by oneself.

[0053] In a preferred embodiment, the "syndiotactic polypropylene (sPP)" described in step (1) is preferably a syndiotactic polypropylene with a crystallinity of 6% - 16%, such as LW0120 (Hunan Liwei), LW0109 (Hunan Liwei).

[0054] In this article, the "isotactic polypropylene (iPP)" described in step (1) is a conventional isotactic polypropylene in the art, which can be of commercial origin or prepared by oneself.

[0055] In a preferred embodiment, the "isotactic polypropylene (iPP)" described in step (1) is preferably an isotactic polypropylene with a crystallinity of 36% - 46%, such as T30S (Dushanzi Petrochemical).

[0056] In one embodiment, the syndiotactic polypropylene (sPP) and isotactic polypropylene (iPP) in step (1) may have feedstock forms including but not limited to powder and pellet, and may also be determined by the applicable feedstock form of the rotary extruder used in step (2). When mixing and preparing for use, it may also include pretreatment processes or other technical means recorded in the prior art applicable to the polypropylene pipe process, such as washing and drying. However, it should be noted that the selection of the above embodiments should be based on not affecting the mass ratio of sPP and iPP.

[0057] In one embodiment, the mass ratio of syndiotactic polypropylene (sPP) to isotactic polypropylene (iPP) is (18 - 22):(78 - 82) or (38 - 42):(58 - 62), such as 18.5:81.5, 19:81, 20:80, 21:79, 21.5:81.5, 38.5:61.5, 39:61, 40:60, 41:59, 41.5:58.5 or any range or point value therebetween.

[0058] In this text, the "rotary extruder" described in step (2) is an extruder with a rotatable extrusion end applicable to pipe preparation. In one embodiment, the rotation of the extrusion end may be a rotatable die, a rotatable mandrel, or both a rotatable die and a rotatable mandrel. It should be noted that the die can also be referred to as the head of the extruder, that is, the rotation of the extrusion end is achieved through the rotation of the head.

[0059] In a preferred embodiment, the "rotary extruder" described in step (2) is the patented device "A device for preparing high-performance polymer pipes" (CN101337425B) independently developed by the applicant of the present invention. Further, for the molten rotary extrusion of the pipe blank, the rotation mode includes any one of the die rotating alone, the mandrel rotating alone, the die and the mandrel rotating in the same direction, and the die and the mandrel rotating in the opposite direction.

[0060] In one embodiment, for the "melt-rotary extrusion tube blank" described in step (2), the rotation rate of the extrusion end is 10 to 40 rpm, such as 12 rpm, 15 rpm, 20 rpm, 25 rpm, 30 rpm, 35 rpm, 38 rpm, or any range or point value therebetween. In a preferred embodiment, substituting the rotation rate of the extrusion end into "a device for preparing high-performance polymer pipes", that is, the above rotation method is also applicable to this rotation rate. Further, the die and the mandrel rotate in the same direction, and the rotation rates of the die and the mandrel can be the same or different; the die and the mandrel rotate in the opposite direction, and the rotation rates of the die and the mandrel can be the same or different. Furthermore, the rotation rate of the extrusion end (die and / or mandrel) can be linearly variable or non-linearly variable, and preferably the range of the variable rotation rate is limited within 10 to 40 rpm.

[0061] It should be noted that when substituting the rotation rate of the extrusion end into "a device for preparing high-performance polymer pipes", the rotation rate range must be limited within 10 to 40 rpm. Below this rotation rate, the holes in the etched pipe wall cannot be connected, while above this rotation rate, it is easy for the molten tube blank to break during the rotary extrusion process, and the product cannot be prepared. In addition, it should be noted that through actual experimental tests, when the reverse rotation method of the die and the mandrel is selected, this rotation rate limit still applies.

[0062] In one embodiment, for the "melt-rotary extrusion tube blank" described in step (2), in addition to the rotation rate of the extrusion end, the other specific process parameters can refer to the existing technologies in the art or the specific processing parameters of the selected syndiotactic polypropylene (sPP) and isotactic polypropylene (iPP), such as the melt temperature window data of commercially available isotactic polypropylene.

[0063] In one embodiment, the "cooling and sizing" described in step (2) is a conventional process method in the field of pipe preparation, such as cooling and sizing the tube blank through a vacuum sizing and cooling device.

[0064] In one embodiment, the selective chemical etching with cyclohexane described in step (3) is carried out at a temperature of 40 °C to 60 °C for 30 min to 90 min; this condition is to meet the selective chemical etching of cyclohexane. If the temperature is lower than 40 °C (such as room temperature 20 - 30 °C), sPP will show a swelling phenomenon rather than dissolution in cyclohexane, and at the same time, too high a temperature is likely to cause safety risks during the use of cyclohexane; the etching time is to ensure that only sPP is etched. If the etching time is too long (exceeding 90 min), the iPP in the sample will also be swollen, resulting in changes in the dimensions of the pipe.

[0065] In one embodiment, the outer diameter of the polypropylene tube in step (2) is set to 1 - 8 mm, and the inner diameter is preferably set at 0.5 - 1.5 mm. It should be noted that after the selective chemical etching in step (3), for the prepared porous polypropylene tube with openings, its size may change negligibly, but it basically does not affect its use.

[0066] The present application will be further explained in detail with reference to the embodiments below. However, those skilled in the art should understand that these embodiments are provided for illustrative purposes only and are not intended to limit the present application.

[0067] Embodiments

[0068] The embodiments of the present application will be described in detail below in conjunction with the embodiments. However, those skilled in the art will understand that the following embodiments are only used to illustrate the present application and should not be regarded as limiting the scope of the present application. For those not specified in the embodiments, the operations are carried out under conventional conditions or conditions recommended by the manufacturer. For those reagents or instruments not specified by the manufacturer, they are all conventional products that can be obtained commercially. The present application should not be construed as being limited to the specific embodiments described.

[0069] 1. Preparation method

[0070] (1) Select syndiotactic polypropylene and isotactic polypropylene, mix them according to the specified mass ratio for standby as the mixture.

[0071] (2) Feed the mixture in step (1) through a rotary extruder to melt and rotarily extrude a tube blank, and then cool and size it to obtain a polypropylene tube with an outer diameter of 3 mm and an inner diameter of 1 mm or 0.5 mm (i.e., a wall thickness of 1 mm or 1.25 mm); wherein, the rotary extruder is the patented device "A device for preparing high-performance polymer tubes" (CN101337425B) independently developed by the applicant of the present invention.

[0072] (3) Immerse the polypropylene tube obtained in step (2) in cyclohexane, and through the selective chemical etching of cyclohexane, etch it for 30 min - 90 min under the temperature condition of 40°C - 60°C to prepare a porous polypropylene tube with openings.

[0073] 2. Testing method

[0074] Observe the samples with a FEI Inspect F-SEM instrument at an acceleration voltage of 20 kV.

[0075] Examples 1 - 2, Comparative Examples 1 - 2

[0076] In Examples 1-2 and Comparative Examples 1-2, the mass ratio of syndiotactic polypropylene (sPP) and isotactic polypropylene (iPP) was studied as a variable, and the obtained open-cell porous polypropylene pipes were prepared as shown in Table 1 below:

[0077] Table 1: Mass ratio as a variable

[0078]

[0079] Surprisingly, it was found through actual experiments that the presence of connected holes inside the pipe wall only occurred in special proportion cases. For this reason, the inventors of this invention application conducted multiple repeated experiments and verifications for the sPP:iPP = 3:7 ratio (Comparative Example 1), and the results were consistent. The reason for this phenomenon is not yet clear. Therefore, based on experimental facts, the protection scope of the present invention has been further limited in a realistic manner.

[0080] Examples 3-6

[0081] In Examples 3-6, the die and mandrel rotation modes and rotation rates of the rotary extruder were studied as variables, and the obtained open-cell porous polypropylene pipes were prepared as shown in Table 2 below:

[0082] Table 1: Die and mandrel rotation as variables

[0083]

[0084] Note: The positive and negative values of the rotation rate are used to distinguish the co-rotation and counter-rotation of the die and the mandrel.

[0085] In Examples 3-6, tests were carried out through different rotation modes respectively, and open-cell porous polypropylene pipes were prepared at rotation rates of 10 rpm, 20 rpm, 30 rpm, and 40 rpm.

[0086] Based on the SEM photo analysis, in the overall trend, the higher the rotation rate, the more obvious the connected holes inside the pipe wall; and based on the evaluation of the obviousness of the connected holes inside the pipe wall, the counter-rotation of the die and the mandrel > the co-rotation of the die and the mandrel > the single rotation of the mandrel ≈ the single rotation of the die.

[0087] Examples 7-10 and Comparative Examples 3-4

[0088] In Examples 7-10 and Comparative Examples 3-4, the variables of the selective chemical etching process conditions of cyclohexane were studied, and the obtained open-cell porous polypropylene pipes were prepared as shown in Table 3 below:

[0089] Table 1: Chemical etching conditions as variables

[0090]

[0091] In Examples 7 to 10, open-cell porous polypropylene pipes were prepared under different chemical etching conditions. After SEM observation, there were no significant differences among the samples.

[0092] In Comparative Example 3, the etching temperature was lower than 40 °C, simulating normal temperature. After SEM observation of the sample, no etching occurred on the surface and inside of the pipe wall, and sPP was not dissolved.

[0093] In Comparative Example 4, the etching time exceeded 90 min. After SEM observation of the sample, although connected holes also appeared inside the pipe wall, due to the swelling of iPP, the problem of serious dimensional deformation of the pipe was too severe to be used as a product.

[0094] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications made without departing from the spirit and principle of the present invention shall be equivalent replacement methods and are all included in the protection scope of the present invention.

Claims

1. A preparation method of a polypropylene pipe with a biomimetic structure for biomedical use, characterized in that It mainly includes the following steps: (1) Select syndiotactic polypropylene and isotactic polypropylene, mix them according to a mass ratio of 4:6 for standby as a mixture; (2) Pass the mixture in step (1) through a rotary extruder to melt and rotarily extrude a tube blank, and then obtain a polypropylene tube through cooling and sizing; wherein, the rotary extruder includes a rotatable extrusion end component; When melting and rotarily extruding the tube blank, the rotational speed of the extrusion end is 30 - 40 rpm; When melting and rotarily extruding the tube blank, the rotation mode is that the die and the mandrel rotate in the same direction; (3) Immerse the polypropylene tube obtained in step (2) in cyclohexane, and prepare an open-cell porous polypropylene tube through selective chemical etching of cyclohexane; The selective chemical etching with cyclohexane is carried out at a temperature of 40 °C for 60 minutes.

2. The open-cell porous polypropylene tube obtained by the preparation method described in claim 1.

3. The application of the open-cell porous polypropylene tube described in claim 2 in the preparation of materials in the biomedical field.

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