Preparation method for polytetrafluoroethylene dual-color spiral heat shrink tube

Abstract

Disclosed are a polytetrafluoroethylene dual-color spiral heat shrink tube, and a preparation method therefor. The method mainly comprises: A and B dual-color mixing; (2) dual-color blank pre-forming; (3) paste extrusion; (4) drying, sintering, and cooling; (5) heat treatment; and (6) inflation. A detachable material barrel is used as the dual-color blank, and the dual-color blank is pressed to obtain a dual-color blank boundary line which is uniform and parallel to the axis. The whole process is simple and efficient, and the prepared dual-color spiral heat shrink tube has good dimensional stability, uniform spiral pitch, and strong and lasting coloring power, and can be fit to an endoscope or other devices, effectively improving guidance and positioning for medical personnel during endoscopic medical treatment, and reducing patient pain.

Description

Preparation method of polytetrafluoroethylene two-color spiral heat shrink tube Technical Field

[0001] The present invention relates to the technical field of medical devices, and more particularly to a method for preparing a medical polytetrafluoroethylene two-color spiral heat shrink tube. Background Art

[0002] In recent years, interventional medicine, unlike traditional internal medicine and surgery, has gained widespread use. Physicians in interventional medicine rely on medical imaging equipment such as CT, MRI, and ultrasound to guide them through the lesions using specialized instruments such as catheters and guidewires. These instruments offer advantages such as minimal incision, high precision, and a wide range of indications. As a modern medical device, endoscopes are inserted through various natural cavities and minimally invasive procedures. Endoscope images are acquired through connection to imaging equipment or direct visual observation. Endoscopes are primarily used in areas such as the digestive system, urinary system, respiratory system, and gynecology. However, in interventional medicine, the time and scope of visualization are limited, making it difficult for attending physicians to accurately locate and quickly navigate internal tissues using cavities or other reference points. To address this issue, researchers and manufacturers have made numerous improvements to medical catheters, such as considering directly coating them. However, this approach makes it difficult to achieve long-term colorfastness and sustained color strength.

[0003] Polytetrafluoroethylene (PTFE) is a high-performance thermoplastic (also known as F4) that is widely used in medical heat shrink tubing due to its high temperature resistance, chemical solvent resistance, stable chemical properties, biocompatibility, non-stickiness, wide long-term use temperature range, and self-cleaning properties.

[0004] The invention with Chinese patent number CN109942867B discloses a method for preparing a color ribbon coating for a polytetrafluoroethylene tube and a polytetrafluoroethylene tube thereof, wherein the preparation process includes: ① preparation and treatment of the polytetrafluoroethylene tube body; ② modification of the color ribbon pigment; ③ coating of the color ribbon pigment on the outer wall of the tube body; ④ curing of the color ribbon coating. In general, the manufacturing of the modified coating material and the surface treatment of the tube improves the navigation and positioning of medical staff in endoscopic medical treatment by adding an annular color ribbon marking coating to the polytetrafluoroethylene tube. The overall operation process of the annular color printing coating method in the prior art is relatively complicated, and the coating method cannot effectively guarantee the neatness of the edge of the color ribbon coating, the uniformity of the coating thickness, the uneven edge of the color ribbon, and the problem of short-lasting coloring ability. Summary of the Invention

[0005] The purpose of the present invention is to provide a medical polytetrafluoroethylene two-color spiral heat shrink tube and a preparation method thereof. The preparation method is relatively simple and suitable for industrial production. The surface of the prepared polytetrafluoroethylene two-color spiral heat shrink tube has spiral stripes of two colors alternating to form a certain pitch, has good dimensional stability and color uniformity, and has long-lasting coloring ability. It can be used in conjunction with an endoscope or other equipment, making it convenient for doctors to accurately locate and navigate internal tissues.

[0006] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0007] The utility model relates to a medical polytetrafluoroethylene two-color spiral heat shrink tube, the surface of which comprises spiral stripes formed by two different colors alternating with each other.

[0008] As a further improved technical solution of the present invention, the two colors of the spiral stripes are at least one of white to blue, white to black, white to yellow, white to green, yellow to blue, black to yellow, black to green, yellow to blue, yellow to green and blue to green.

[0009] A method for preparing a medical polytetrafluoroethylene two-color spiral heat shrink tubing comprises the following steps:

[0010] Step S1: A and B two-color mixing:

[0011] Step S11: Place the sieved polytetrafluoroethylene dispersion resin into a dry and clean material barrel according to a certain proportion, add the extrusion aid oil and color paste A in sequence, mix well, and mature at a constant temperature to obtain color A mixed material;

[0012] Step S12: Place the sieved polytetrafluoroethylene dispersion resin into a dry and clean material barrel according to a certain proportion, add extrusion aid oil and color paste B in sequence, mix well, and mature at a constant temperature to obtain color B mixed material;

[0013] Step S2: Preforming of two-color blanks:

[0014] The A-color mixed material and the B-color mixed material are respectively made into an A-color semi-circular tube blank and a B-color semi-circular tube blank, and the A-color semi-circular tube blank and the B-color semi-circular tube blank can be butted together to form a two-color circular tube blank;

[0015] Step S3: Pushing and extruding:

[0016] The color A semi-circular tube blank and the color B semi-circular tube blank obtained in step S2 are placed in the material cavity of the second extruder, the color A semi-circular tube blank and the color B semi-circular tube blank are butted together to form a two-color circular body, and the body is extruded through a die coaxial with the material cavity and rotating around the axis to obtain a two-color spiral prefabricated pipe;

[0017] Step S4: drying, sintering, and cooling:

[0018] The two-color spiral prefabricated pipe is dried, sintered, and naturally cooled in sequence to obtain a polytetrafluoroethylene two-color spiral pipe;

[0019] Step S5: heat treatment:

[0020] The polytetrafluoroethylene two-color spiral tube obtained in step S4 is heat-treated again;

[0021] Step S6, inflation:

[0022] After heat treatment, the polytetrafluoroethylene two-color spiral tube is quickly passed through the inflation machine to fill the compressed gas, and then cooled;

[0023] Finally, a polytetrafluoroethylene two-color spiral heat shrink tube was obtained.

[0024] As a further improved technical solution of the present invention, in the step S11, the aging temperature is 25-30°C, and the aging time is more than 12 hours; in the step S12, the aging temperature is 25-30°C, and the aging time is more than 12 hours.

[0025] As a further improved technical solution of the present invention, in the step S11, according to the weight ratio: polytetrafluoroethylene dispersion resin accounts for 75-85%, and extrusion-aiding oil accounts for 15-25%; in the step S12, according to the weight ratio: polytetrafluoroethylene dispersion resin accounts for 75-85%, and extrusion-aiding oil accounts for 15-25%.

[0026] As a further improved technical solution of the present invention, the color paste A or color paste B is a liquid color paste resistant to sintering temperature; the color paste A in step S11 is added in an amount of 0.2-1% of the total weight of the polytetrafluoroethylene dispersion resin and the extrusion-aid oil; the color paste B in step S12 is added in an amount of 0.2-1% of the total weight of the polytetrafluoroethylene dispersion resin and the extrusion-aid oil.

[0027] As a further improved technical solution of the present invention, in step S4, the drying temperature is 100°C, the sintering temperature is 380-450°C, and the sintering time is 20-40 seconds; in step S5, the heat treatment temperature is 360°C; in step S6, after the heat treatment, it is quickly passed through an inflation machine, filled with compressed gas below 0.98MPa, with an inflation rate of 200%-400%, and then cooled.

[0028] As a further improved technical solution of the present invention, in step S2, a cylinder is used to prepare a two-color ring blank;

[0029] The cylinder includes a cylinder body; the cylinder body is a semicircular ring, the side plane of the cylinder body is in contact with the inner surface of the partition, and arc-shaped flanges extending parallel to the axis of the cylinder body are provided on both sides of the partition, and the arc-shaped flanges are in contact with the arc surface of the cylinder body. A semi-cylinder coaxial with the cylinder body is provided on the inner surface of the partition, and a blocking plate is provided at one end in the axial direction of the cylinder body and the partition, and the blocking plate is used to block one end port of the internal space surrounded by the inner surface of the cylinder body, the inner surface of the partition, and the outer arc surface of the semi-cylinder;

[0030] A pressure block is provided at the other end of the cylinder body and the partition in the axial direction. The pressure block is used to block the other end port of the internal space. The pressure block can move along the axial direction of the cylinder body under the action of external force to compress the mixture in the internal space.

[0031] There are two cylinder bodies, which are respectively recorded as cylinder body 1 and cylinder body 2. When the side plane of cylinder body 1 is fitted with the side plane of cylinder body 2, a circular cylinder is formed.

[0032] The step S2 is specifically as follows:

[0033] Step S21: Assemble the cylinder body 1 and a partition together, with the side plane of the cylinder body 1 fitting against the inner surface of the partition, and add the color A mixed material into the internal space; use an auxiliary tool to apply a certain pressure to the color A mixed material so that the color A mixed material in the internal space is shaped into a color A semi-circular tube blank, remove the partition and the blocking plate, and the color A semi-circular tube blank is not loose;

[0034] Step S22: Assemble the second cylinder body and a partition together, with the side plane of the second cylinder body fitting the inner surface of the partition, and add the color B mixed material into the internal space; use auxiliary tools to apply a certain pressure to the color B mixed material so that the color B mixed material in the internal space is shaped into a color B semi-circular tube blank, remove the partition and the blocking plate, and the color B semi-circular tube blank is not loose;

[0035] Step S23: The cylinder body containing the A-color semi-circular tube blank is butted and enclosed with the cylinder body containing the B-color semi-circular tube blank to obtain a circular cylinder containing a two-color circular tube blank, and the two-color circular tube blank is extruded from the circular cylinder by an extrusion device to obtain a two-color circular blank.

[0036] As a further improved technical solution of the present invention, the extruder 2 in step S3 includes an extruder head, a core die, a cone die and a rotatable die structure;

[0037] The bottom of the extruder head is connected to the top of the core mold, the top of the cone mold is connected to the bottom of the extruder head, and the core mold is located in the inner cavity of the cone mold and the inner cavity of the mouth mold;

[0038] The rotatable die structure includes a transmission shaft, a die flange, a die, and a rotation drive mechanism. The transmission shaft is rotatably arranged in the center hole of the die flange. A die receiving groove is provided on the top of the transmission shaft, and the die is connected to the die receiving groove. The rotation drive mechanism is in transmission connection with the transmission shaft to drive the transmission shaft and the die to rotate relative to the die flange.

[0039] The bottom of the cone die is connected to the top of the die flange, and the bottom of the cone die is in rotatable contact with the top of the die;

[0040] The center line of the extruder head cavity, the center line of the cone die, the center line of the core die, the center line of the die and the center line of the drive shaft are located on the same straight line;

[0041] The material cavity inside the extruder head, the inner cavity of the cone die, the inner cavity of the mouth die, and the center hole of the transmission shaft are connected in sequence;

[0042] The step S3 is specifically as follows:

[0043] The two-color circular ring blank obtained in step S2 is placed in the material cavity of the extruder head, and the extruder head, the cone die, and the rotatable die structure are connected in sequence. The extrusion drive mechanism connected to the second piston in the extruder head is turned on, and the extrusion drive mechanism applies a pushing force to the second piston. At the same time, the rotation drive mechanism is turned on, and the rotation drive mechanism drives the die to rotate through the transmission shaft. Therefore, the blank in the material cavity is subjected to the pushing force of the second piston, passes through the cone die and enters the die in a rotating state. The paste blank is passively subjected to force and rotates, and a two-color spiral prefabricated pipe is obtained after pushing.

[0044] The beneficial effects of the present invention are:

[0045] To facilitate the addition of two-color mixed materials, the present invention utilizes a detachable cylinder during the pre-pressing process. This cylinder comprises a cylinder body and a partition. The two cylinder bodies can be docked to form a single-piece cylinder. The partition is flanked by flanges that mate with the curved surface of the cylinder body, with a raised semi-cylindrical structure in the center. This detachable cylinder is easy to clean and hygienic, with a simple and efficient assembly. It can produce two-color blanks with uniform color, with the boundary between the two colors substantially parallel to the axis.

[0046] 2. In step S2, it is more convenient to prepare semi-circular tube blanks using a semi-circular tube blank preparation device composed of a cylinder body, a partition, a blocking plate, etc. Flangings that can fit with the arc surface of the cylinder body are set on both sides of the partition, and there is a raised semi-cylindrical structure in the middle of the partition. The flanging can ensure that the partition will not be separated from the cylinder body when the mixture is pre-pressed, and the flanging will not affect the axial movement of the partition relative to the cylinder body, making it convenient to remove the partition. As a semi-circular plate, the blocking plate has a simple structure and is more convenient to use. The use of a pressing block facilitates the pre-pressing of the mixture.

[0047] The semi-circular tube blank can be produced by using the semi-circular tube blank production device. The semi-circular tube blank is removed from the production device and is surrounded and butted with two semi-circular tube blanks of different colors to produce a two-color tube blank, wherein the two semi-circular tube blanks of different colors are symmetrically distributed.

[0048] 3. When using two cylinder bodies, it is only necessary to separate the partition plate, blocking plate, etc. from the cylinder body. There is no need to separate the semi-circular tube blank from the cylinder body. The two cylinder bodies are connected to form one cylinder, and at the same time, the two semi-circular tube blanks are connected to form a two-color circular tube blank. The cylinder is connected to the frame in a detachable manner, and the extrusion cylinder can be used to extrude the two-color tube blank, which greatly improves the working efficiency.

[0049] 4. The transition ring is formed by connecting half ring 1 and half ring 2 in a closed-jointed manner. The transition ring is detachably connected to the frame, further improving the efficiency of connecting the cylinder to the frame. The connection between half ring 1 and half ring 2 also prevents the two cylinder bodies from separating.

[0050] 5. In step S3, extruder 2 utilizes a rotatable die structure. When the extruder head is operating, it pushes the two-color circular ring blank along a conical die into a counterclockwise rotating die. In the rotating die, the PTFE blank is primarily subjected to thrust and rotational forces, forming a PTFE two-color spiral preformed tubing. The extruded two-color spiral preformed tubing exhibits excellent stability, uniform pitch, and strong, long-lasting tinting power. After subsequent drying and heat treatment, the resulting two-color spiral tubing can be used for medical catheters.

[0051] 6. The process of the present invention is simple and efficient. A two-color spiral pre-pressed tube is prepared through a rotatable die structure and a push extrusion process. After drying, sintering, cooling, heat treatment, and inflation process, a polytetrafluoroethylene two-color spiral heat shrinkable tube with uniform pitch is finally obtained.

[0052] 7. The two-color spiral heat shrink tubing prepared by the present invention has good dimensional stability, uniform pitch, strong and lasting tinting strength, and can be used in conjunction with an endoscope or other equipment to effectively improve the navigation and positioning of medical staff in endoscopic medical treatment, enable accurate operation, and reduce patient pain. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Figures 1 and 2 are three-dimensional views of the cylinder body respectively;

[0054] Figures 3 and 4 are three-dimensional views of the partition respectively;

[0055] Figure 5 is a schematic diagram of the assembly of the partition plate, cylinder body, and pressure block;

[0056] FIG6 is a DD sectional view of FIG5;

[0057] FIG7 is a cross-sectional view taken along line EE of FIG5 ;

[0058] Figures 8 and 9 are perspective views of the cylinder body and the extrusion device connected together;

[0059] FIG10 is a front view of the cylinder body and the like connected to the extrusion device 1 of Example 1;

[0060] FIG11 is a cross-sectional view taken along line AA of FIG10 ;

[0061] FIG12 is a left side view of FIG10;

[0062] FIG13 is a cross-sectional view taken along line CC of FIG10 ;

[0063] Figures 14 and 15 are perspective views of the cylinder body and the like connected to the extrusion device 1;

[0064] Figures 16, 17 and 18 are three-dimensional views of the stopper sleeve respectively.

[0065] FIG19 is a cross-sectional schematic diagram of the extruder 2;

[0066] FIG20 is a partial enlarged view of A in FIG19 .

[0067] FIG21 is a state diagram showing the die rotating to form a two-color spiral prefabricated pipe.

[0068] Explanation of the accompanying symbols: 1. Cylinder body; 2. Partition plate; 21. Flanged edge; 22. Semi-cylinder; 3. Blocking plate; 4. Pressing block; 5. Transition connection half ring; 6. Screw; 11. Cylinder body one; 12. Cylinder body two; 13. Cylinder; 14. Side plane; 15. Screw hole; 16. Screw hole; 51. Transition connection half ring one; 52. Transition connection half ring two; 53. Transition connection ring; 55. Clamping part one; 56. Clamping part two; 59. Transition connection screw; 71. Clamping groove one; 72. Clamping groove two; 81. A-color semi-circular ring tube blank; 82. B-color semi-circular ring tube blank; 9. Stopper sleeve; 92. Intermediate body; 91. Front end plate; 93. Rear stopper ring; 95. Semi-ring groove one; 96. Semi-ring groove two; 97. Ring groove; 99. Ring stopper; 100, Extrusion device 1; 200, Core rod; 300, Piston 1; 400, Frame; 500, Cylinder; 101, PTFE capillary; 102, Flat key; 103, Synchronous pulley A; 104, Transmission shaft; 105, Spring retaining ring; 106, Deep groove ball bearing (1); 107. Locking screw (1); 108. Bearing seat; 109. Plane bearing; 1010. Convex end locking screw; 1011. Deep groove ball bearing (2); 1012. Mouth die flange; 1013. Locking screw (2); 1014. Mouth die; 1015. Cone die flange; 1016. Core die; 1017. Cone die; 1018. Locking screw (3); 1019. PTFE blank tube; 1020. Piston (2); 1021. Pushing tube; 1022. Machine body; 1023. Servo motor; 1024. Planetary reducer; 1025. Mounting plate; 1026. Synchronous belt; 1027. Synchronous pulley B; 1028. Core die connecting rod. DETAILED DESCRIPTION

[0069] The specific embodiments of the present invention are further described below with reference to the accompanying drawings:

[0070] Example 1:

[0071] A medical polytetrafluoroethylene two-color spiral heat shrink tube has spiral stripes formed by alternating two different colors on the tube surface, and the spacing of the spiral stripes is adjustable.

[0072] The preparation method of the above-mentioned medical polytetrafluoroethylene two-color spiral heat shrink tube comprises the following steps:

[0073] Step S1: mixing two colors A and B;

[0074] Weigh the raw materials by weight: 85 parts polytetrafluoroethylene dispersion resin, 15 parts extrusion aid oil, and 1 part white color paste. Place the polytetrafluoroethylene dispersion resin in a dry, clean barrel. Premix the white color paste (i.e., color paste A) and extrusion aid oil, then add the polytetrafluoroethylene dispersion resin. Mix the three ingredients evenly and mature at a constant temperature of 25-30°C for at least 12 hours to obtain a white mixture.

[0075] Then, the raw materials were weighed in the same manner, except that the color paste was blue (i.e., color paste B), to obtain a blue mixed material;

[0076] Step S2: preforming a two-color blank;

[0077] After aging, the white mixed material and the blue mixed material are preformed using a cylinder 13 with an outer diameter of 30mm-100mm, and pressure is applied to obtain a two-color ring blank;

[0078] Step S3: paste extrusion;

[0079] The two-color circular ring body obtained in step S2 is placed into the material cavity of the second vertical extruder and paste extruded to obtain a two-color spiral prefabricated pipe;

[0080] Step S4: drying, sintering, and cooling;

[0081] The two-color spiral prefabricated pipe is dried at a drying temperature of 100° C. The dried prefabricated pipe is placed in a sintering furnace for high-temperature sintering at a temperature of 380° C. for 40 seconds. After sintering, the prefabricated pipe is naturally cooled at room temperature to obtain a polytetrafluoroethylene two-color spiral pipe.

[0082] Step S5: heat treatment;

[0083] The polytetrafluoroethylene two-color spiral tube obtained in step S4 is heat-treated again at a temperature of about 360°C;

[0084] Step S6: inflation;

[0085] After heat treatment, it quickly passes through an inflation machine and is filled with compressed gas below 0.98 MPa with an inflation rate of 200%, and then cooled.

[0086] Example 2:

[0087] A medical polytetrafluoroethylene two-color spiral heat shrink tube has spiral stripes formed by alternating two different colors on the tube surface, and the spacing of the spiral stripes is adjustable.

[0088] The preparation method of the above-mentioned medical polytetrafluoroethylene two-color spiral heat shrink tube comprises the following steps:

[0089] Step S1: mixing two colors A and B;

[0090] Weigh the raw materials by weight: 80 parts polytetrafluoroethylene dispersion resin, 20 parts extrusion aid oil, and 0.5 parts white color paste. Place the polytetrafluoroethylene dispersion resin into a dry, clean material barrel. Premix the white color paste and extrusion aid oil first, then add the polytetrafluoroethylene dispersion resin. Mix the three ingredients evenly and mature at a constant temperature of 25-30°C for at least 12 hours to obtain a white mixture.

[0091] Then, the raw materials were weighed in the same manner, except that the color paste was yellow, to obtain a yellow mixed material;

[0092] Step S2: preforming a two-color blank;

[0093] After aging, the white mixture and the yellow mixture are preformed using a cylinder 13 with an outer diameter of 30mm-100mm, and pressure is applied to obtain a two-color ring blank;

[0094] Step S3: paste extrusion;

[0095] The two-color circular ring body obtained in step S2 is placed into the material cavity of the second extruder and paste extruded to obtain a two-color spiral prefabricated pipe;

[0096] Step S4: drying, sintering, and cooling;

[0097] The two-color spiral prefabricated pipe is dried at a drying temperature of 100°C; the dried prefabricated pipe is placed in a sintering furnace for high-temperature sintering at a temperature of 410°C for 30 seconds; after sintering, the pipe is naturally cooled at room temperature to obtain a polytetrafluoroethylene two-color spiral pipe.

[0098] Step S5: heat treatment; the polytetrafluoroethylene two-color spiral tube obtained in step S4 is heat treated again at a temperature of about 360°C;

[0099] Step S6: inflation;

[0100] After heat treatment, it is quickly passed through an inflation machine and filled with compressed gas below 0.98 MPa, with an inflation rate of 200%, and then cooled.

[0101] Example 3:

[0102] A medical polytetrafluoroethylene two-color spiral heat shrink tube has spiral stripes formed by alternating two different colors on the tube surface, and the spacing of the spiral stripes is adjustable.

[0103] The preparation method of the above-mentioned medical polytetrafluoroethylene two-color spiral heat shrink tube comprises the following steps:

[0104] Step S1: mixing two colors A and B;

[0105] Weigh the raw materials by weight: 75 parts polytetrafluoroethylene dispersion resin, 25 parts extrusion aid oil, and 0.2 parts white color paste. Place the polytetrafluoroethylene dispersion resin into a dry, clean material barrel. Premix the white color paste and extrusion aid oil first, then add the polytetrafluoroethylene dispersion resin. Mix the three together thoroughly and mature at a constant temperature of 25-30°C for at least 12 hours to obtain a white mixture.

[0106] Then, the raw materials were weighed in the same manner, except that the color paste was black, to obtain a black mixed material;

[0107] Step S2: preforming a two-color blank;

[0108] After aging, the white mixed material and the black mixed material are preformed using a cylinder 13 with an outer diameter of 30mm-100mm, and pressure is applied to obtain a two-color ring blank;

[0109] Step S3: paste extrusion;

[0110] The two-color circular ring body obtained in step S2 is placed into the material cavity of the second extruder and paste extruded to obtain a two-color spiral prefabricated pipe;

[0111] Step S4: drying, sintering, and cooling;

[0112] The two-color spiral prefabricated pipe is dried at a drying temperature of 100° C. The dried prefabricated pipe is placed in a sintering furnace for high-temperature sintering at a temperature of 380° C. for 40 seconds. After sintering, the prefabricated pipe is naturally cooled at room temperature to obtain a polytetrafluoroethylene two-color spiral pipe.

[0113] Step S5: heat treatment;

[0114] The polytetrafluoroethylene two-color spiral tube obtained in step S4 is heat-treated again at a temperature of about 360°C;

[0115] Step S6: inflation;

[0116] After heat treatment, it passes through an inflation machine quickly and is filled with compressed gas below 0.98 MPa with an inflation rate of 300%, and then cooled.

[0117] Example 4:

[0118] A medical polytetrafluoroethylene two-color spiral heat shrink tube has spiral stripes formed by alternating two different colors on the tube surface, and the spacing of the spiral stripes is adjustable.

[0119] The preparation method of the above-mentioned medical polytetrafluoroethylene two-color spiral heat shrink tube comprises the following steps:

[0120] Step S1: mixing two colors A and B;

[0121] Weigh the raw materials by weight: 85 parts polytetrafluoroethylene dispersion resin, 15 parts extrusion aid oil, and 1 part white color paste. Place the polytetrafluoroethylene dispersion resin into a dry, clean barrel. Premix the white color paste and extrusion aid oil first, then add the polytetrafluoroethylene dispersion resin. Mix the three ingredients evenly and mature at a constant temperature of 25-30°C for at least 12 hours to obtain a white mixture.

[0122] Then, the raw materials were weighed in the same manner, except that the color paste was green, to obtain a green mixed material;

[0123] Step S2: preforming a two-color blank;

[0124] After aging, the white and green mixtures are preformed using a cylinder 13 with an outer diameter of 30 mm to 100 mm, and pressure is applied to obtain a two-color circular ring-shaped blank;

[0125] Step S3: paste extrusion;

[0126] The two-color annular blank obtained in step S2 is placed into the material cavity of the second extruder and paste extruded to obtain a two-color spiral prefabricated pipe;

[0127] Step S4: drying, sintering, cooling, and stretching;

[0128] The two-color spiral prefabricated pipe is dried at a drying temperature of 100°C; the dried prefabricated pipe is placed in a sintering furnace for high-temperature sintering at a temperature of 450°C for 20 seconds; after sintering, it is naturally cooled at room temperature, and then the two-color prefabricated pipe is passed through a fully automatic stretching device to obtain a two-color spiral pipe, thereby obtaining a polytetrafluoroethylene two-color spiral pipe.

[0129] Step S5: heat treatment;

[0130] The polytetrafluoroethylene two-color spiral tube obtained in step S4 is heat-treated again at a temperature of about 360°C;

[0131] Step S6: inflation;

[0132] After heat treatment, it passes through an inflation machine quickly and is filled with compressed gas below 0.98 MPa with an inflation rate of 200%-400%, and then cooled.

[0133] Example 5:

[0134] A medical polytetrafluoroethylene two-color spiral heat shrink tube has spiral stripes formed by alternating two different colors on the tube surface, and the spacing of the spiral stripes is adjustable.

[0135] The preparation method of the above-mentioned medical polytetrafluoroethylene two-color spiral heat shrink tube comprises the following steps:

[0136] Step S1: mixing two colors A and B;

[0137] Weigh the raw materials by weight: 80 parts polytetrafluoroethylene dispersion resin, 20 parts extrusion aid oil, and 0.5 parts yellow color paste. Place the polytetrafluoroethylene dispersion resin into a dry, clean material barrel. Premix the yellow color paste and extrusion aid oil first, then add the polytetrafluoroethylene dispersion resin. Mix the three together thoroughly and mature at a constant temperature of 25-30°C for at least 12 hours to obtain the yellow mixture.

[0138] Then, the raw materials were weighed in the same manner, except that the color paste was blue, to obtain a blue mixed material;

[0139] Step S2: preforming a two-color blank;

[0140] After aging, the yellow mixed material and the blue mixed material are preformed using a cylinder 13 with an outer diameter of 30mm-100mm, and pressure is applied to obtain a two-color ring blank;

[0141] Step S3: paste extrusion;

[0142] The two-color circular ring body obtained in step S2 is placed into the material cavity of the second extruder and paste extruded to obtain a two-color spiral prefabricated pipe;

[0143] Step S4: drying, sintering, cooling, and stretching;

[0144] The two-color spiral prefabricated pipe is dried at a drying temperature of 100°C; the dried prefabricated pipe is placed in a sintering furnace for high-temperature sintering at a temperature of 450°C for 20 seconds; after sintering, it is naturally cooled at room temperature, and then the two-color prefabricated pipe is passed through a fully automatic stretching device to obtain a two-color spiral pipe, thereby obtaining a polytetrafluoroethylene two-color spiral pipe.

[0145] Step S5: heat treatment;

[0146] The polytetrafluoroethylene two-color spiral tube obtained in step S4 is heat-treated again at a temperature of about 360°C;

[0147] Step S6: inflation;

[0148] After heat treatment, it quickly passes through an inflation machine and is filled with compressed gas below 0.98 MPa with an inflation rate of 400%, and then cooled.

[0149] Example 6:

[0150] A medical polytetrafluoroethylene two-color spiral heat shrink tube has spiral stripes formed by alternating two different colors on the tube surface, and the spacing of the spiral stripes is adjustable.

[0151] The preparation method of the above-mentioned medical polytetrafluoroethylene two-color spiral heat shrink tube comprises the following steps:

[0152] Step S1: mixing two colors A and B;

[0153] Weigh the raw materials by weight: 75 parts polytetrafluoroethylene dispersion resin, 25 parts extrusion aid oil, and 0.2 parts black color paste. Place the polytetrafluoroethylene dispersion resin into a dry, clean material barrel. Premix the black color paste and extrusion aid oil first, then add the polytetrafluoroethylene dispersion resin. Mix the three together thoroughly and mature at a constant temperature of 25-30°C for at least 12 hours to obtain the black mixture.

[0154] Then, the raw materials were weighed in the same manner, except that the color paste was yellow, to obtain a yellow mixed material;

[0155] Step S2: preforming a two-color blank;

[0156] After aging, the black mixed material and the yellow mixed material are preformed using a cylinder 13 with an outer diameter of 30mm-100mm, and pressure is applied to obtain a two-color ring blank;

[0157] Step S3: paste extrusion;

[0158] The two-color circular ring body obtained in step S2 is placed into the material cavity of the second extruder and paste extruded to obtain a two-color spiral prefabricated pipe;

[0159] Step S4: drying, sintering, cooling, and stretching;

[0160] The two-color spiral prefabricated pipe is dried at a drying temperature of 100°C; the dried prefabricated pipe is placed in a sintering furnace for high-temperature sintering at a temperature of 380°C for 40 seconds; after sintering, it is naturally cooled at room temperature, and then the two-color prefabricated pipe is passed through a fully automatic stretching device to obtain a two-color spiral pipe, thereby obtaining a polytetrafluoroethylene two-color spiral pipe.

[0161] Step S5: heat treatment;

[0162] The polytetrafluoroethylene two-color spiral tube obtained in step S4 is heat-treated again at a temperature of about 360°C;

[0163] Step S6: inflation;

[0164] After heat treatment, it quickly passes through an inflation machine and is filled with compressed gas below 0.98 MPa with an inflation rate of 400%, and then cooled.

[0165] In addition to Examples 1-6, the two colors of the spiral stripes of the medical polytetrafluoroethylene two-color spiral heat shrink tubing can also be at least one of black to green, yellow to blue, yellow to green, and blue to green.

[0166] In Examples 1-6, the purpose of heat treatment is that thermoplastic materials are in a glassy state at room temperature and become highly elastic upon heating. Heat treatment is intended to molten the thermoplastic tubing (PTFE has a melting point of 330°C), allowing it to deform easily and expand radially. The purpose of inflation is to quickly and easily wrap tightly around the component to be protected, requiring radial expansion. The heat shrink tubing material becomes highly elastic upon heating, and a load is applied to cause radial expansion. Rapid cooling, while maintaining this radial expansion, causes it to enter a glassy state. The inflated tubing, after heat shrinking, is then wrapped to provide the necessary wrapping force to tightly enclose the core material.

[0167] In Examples 1-6, preforming is performed in step S2 using a cylinder 13 from a two-color tube blank production apparatus. Referring to Figures 5-8 , the two-color tube blank production apparatus includes the cylinder 13, a partition 2, a blocking plate 3, a pressing block 4, a transition ring 5, a screw 6, and the like. The cylinder 13 includes a cylinder body 1. Each of the cylinder body 1, partition 2, blocking plate 3, pressing block 4, and transition ring 5 consists of two pieces, and their structures are essentially identical.

[0168] The two cylinder bodies 1 are cylinder body one 11 and cylinder body two 12 , and the two transition connection half rings 5 ​​are transition connection half ring one 51 and transition connection half ring two 52 .

[0169] 1-4, the cylinder body 1 is a semicircular ring, the side plane 14 of the cylinder body is in contact with the inner surface of the partition 2, and arc-shaped flanges 21 extending parallel to the axis of the cylinder body 1 are provided on both sides of the partition 2. The arc-shaped flanges 21 are in contact with part of the arc surface of the cylinder body 1, and a semi-cylinder 22 coaxial with the cylinder body 1 is provided on the inner surface of the partition 2. A blocking plate 3 is provided at one end of the axial direction of the cylinder body 1 and the partition 2. The blocking plate 3 is a semicircular plate in contact with the end face of the cylinder body, the end face of the semi-cylinder and the end face of the partition. The blocking plate 3 is fixed to one end of the partition 2 and is used to seal one end port of the internal space surrounded by the inner surface of the cylinder body, the inner surface of the partition and the outer arc surface of the semi-cylinder.

[0170] A pressure block 4 is provided at the other end of the cylinder body 1 and the partition 2 in the axial direction. The pressure block 4 is used to seal the other end port of the internal space. The pressure block 4 can move along the axial direction of the cylinder body under the action of external force to compress the mixture including polytetrafluoroethylene in the internal space.

[0171] When the side plane of the cylinder body 1 1 and the side plane of the cylinder body 2 12 are fitted together, they can form an annular cylinder 13 .

[0172] A plurality of countersunk screw holes 15 and a plurality of through screw holes 16 are provided on the side planes 14 of the two cylinder bodies. The screw holes 15 on one cylinder body are opposite to the screw holes 16 on the other cylinder body. The screws 6 pass through the screw holes on one cylinder body and are threadedly connected to the screw holes on the other cylinder body, thereby detachably connecting the two cylinder bodies that constitute the cylinder.

[0173] Cylinder body 11 has a first latching groove 71 formed on one end of its outer surface, while cylinder body 2 has a second latching groove 72 formed on one end of its outer surface. Transition ring 1 51 has a first latching portion 55 that extends into slot 1, while transition ring 2 52 has a second latching portion 56 that extends into slot 2. The detachable connection between transition rings 1 and 2 is similar to that between the two cylinder bodies and will not be further described.

[0174] A semi-annular groove 1 95 is formed on the outer surface of the other end of the cylinder body 1, and a semi-annular groove 2 96 is formed on the outer surface of the other end of the cylinder body 2. When the cylinder body 1 and the cylinder body 2 are connected to form a cylinder, the semi-annular groove 1 and the semi-annular groove 2 form an annular groove 97 on the cylinder;

[0175] The transition connection half ring 1 and the transition connection half ring 2 are provided with through holes for passing screws.

[0176] In Examples 1-6, step S2 includes the following steps:

[0177] Step S21, referring to Figures 5-7 and 13, prepares a color A semi-circular tube blank 81: Insert the cylinder body 11 axially into the partition 2 until the blocking plate 3 seals one end of the internal space defined by the inner surface of the cylinder body 11, the inner surface of the partition, and the outer arc surface of the semi-cylinder. Add a mixture containing color A into the internal space; apply pressure to the mixture using an auxiliary tool or a pressing block, shaping the mixture into the color A semi-circular tube blank 81. Remove the auxiliary tool or pressing block. Pull the partition along the axis to separate it from the cylinder body 11, obtaining the cylinder body 11 containing the color A semi-circular tube blank 81.

[0178] Step S22: Using a method similar to the above, add the B-color mixed material into the internal space surrounded by the inner surface of the cylinder body 12, the inner surface of another partition 2, and the outer arc surface of the semi-cylinder to prepare the cylinder body 12 containing the B-color semi-circular ring tube 82 inside.

[0179] Step S23, referring to Figures 8-13, cylinder body 11 containing color A semi-circular ring tube 81 and cylinder body 2 12 containing color B semi-circular ring tube 82 are joined together to form cylinder 13. The color A semi-circular ring tube 81 and the color B semi-circular ring tube 82 are joined together to form a two-color circular ring tube. During this joining, the core rod 200 in the extrusion device 100 passes through the center of the two-color circular ring tube. Screws 6 are used to connect cylinder body 11 and cylinder body 2 12.

[0180] Step S24: Snap-on portion 1 55 on transition connecting half ring 1 51 extends into snap-on groove 1 71, snap-on portion 2 56 on transition connecting half ring 2 52 extends into snap-on groove 2 72. Screws 6 are used to connect transition connecting half ring 1 51 and transition connecting half ring 2 52. Transition connecting half ring 1 51 and transition connecting half ring 2 52 are connected to the frame 400 of extruder 1 using transition connecting screws 59 that pass through through holes. Piston 1 300 in extruder 1 is slidably mounted on core rod 200, and piston 1 mates with the cylinder barrel.

[0181] Step S25: The oil cylinder 500 in the extrusion device 1 is actuated, and the piston 1 300 moves along the core rod in the cylinder 13 to extrude the two-color circular tube blank from the cylinder.

[0182] The diameter (inner diameter) of the cylinder is 30 mm, and the thickness of the partition 2 is 1.5 mm. Each cylinder body is provided with 6 screw holes, which are staggered. The cylinder body is made of stainless steel.

[0183] In Examples 1-6, as shown in Figures 19-20, the extruder 2 in step S3 includes an extruder head, a core die 1016, a cone die 1017 and a rotatable die structure.

[0184] As shown in Figures 19-20, the extruder head adopts the head of a vertical extruder, including a body 1022, a pushing tube 1021, a core mold connecting rod 1028 and a second piston 1020. A material cavity is provided inside the body 1022, and the core mold connecting rod 1028 is installed on the axial center line inside the body 1022. The pushing tube 1021 is connected to the second piston 1020. The pushing tube 1021 and the second piston 1020 are located in the material cavity and are used to be driven by the extrusion drive mechanism to reciprocate up and down along the core mold connecting rod 1028. The top of the core mold 1016 is threadedly connected to the bottom of the core mold connecting rod 1028.

[0185] The bottom of the machine body 1022 is provided with a lower groove, and the top of the cone mold 1017 is embedded in the lower groove. The cone mold 1017 is connected to the cone mold flange 1015, and the cone mold flange 1015 is connected to the machine body 1022 by locking screw three 1018.

[0186] As shown in Figures 1-2, the rotatable die structure includes a drive shaft 104, a die flange 1012, a die 1014, and a rotary drive mechanism. The rotary drive mechanism is in driving connection with the drive shaft 104, which is rotatably connected to the center hole of the die flange 1012. A die receiving groove is defined at the top of the drive shaft 104, into which the die 1014 is connected. The drive shaft 104 is connected to the die 1014 via a convex end locking screw 1010. A core die 1016 is positioned within the inner cavities of the cone die 1017 and the die 1014. The bottom of the core die 1016 is flush with the bottom of the die 1014.

[0187] The top of the die flange 1012 is provided with an upper groove, the top of the cone die 1017 is embedded in the upper groove, and the cone die flange 1015 is connected to the die flange 1012 by a locking screw 1013. The bottom of the cone die 1017 is in rotatable contact with the top of the die 1014.

[0188] The center line of the material cavity of the extruder head, the center line of the cone die 1017, the center line of the core die 1016, the center line of the mouth die 1014 and the center line of the transmission shaft 104 are located on the same straight line.

[0189] The material cavity inside the extruder head is connected to the inner cavity of the cone die 1017 , the inner cavity of the cone die 1017 is connected to the inner cavity of the mouth die 1014 , and the inner cavity of the mouth die 1014 is connected to the center hole of the transmission shaft 104 .

[0190] The rotary drive mechanism uses a servo motor 1023. The servo motor 1023 is connected to a synchronous pulley B1027 via a planetary reducer 1024. The planetary reducer 1024 is mounted on a mounting plate 1025. The synchronous pulley B1027 is connected to the synchronous pulley A103 via a synchronous belt 1026. The synchronous pulley A103 is connected to one end of the transmission shaft 104 via a flat key 102.

[0191] The mounting plate 1025 is connected to a bearing seat 108. The drive shaft 104 passes through the center hole of the bearing seat 108 and the die flange 1012. The drive shaft 104 and the bearing seat 108 are rotatably connected via a deep groove ball bearing 106. The drive shaft 104 and the center hole of the die flange 1012 are rotatably connected via a plane bearing 109 and a deep groove ball bearing B. The mounting plate 1025, the bearing seat 108, and the die flange 1012 are connected via a locking screw 107.

[0192] The rotatable die structure includes a flat key 102, a synchronous pulley A103, a transmission shaft 104, a spring retaining ring 105, a deep groove ball bearing 106, a locking screw 107, a bearing seat 108, a plane bearing 109, a convex end locking screw 1010, a deep groove ball bearing 2 1011, a die flange 1012, a locking screw 2 1013, a die 1014, a servo motor 1023, a planetary reducer 1024, a mounting plate 1025, a synchronous belt 1026, and a synchronous pulley B1027. The synchronous pulley A103 is connected to the synchronous pulley B1027 through the synchronous belt 1026. The synchronous pulley B1027 is connected to the planetary reducer 1024. The transmission shaft 104 is connected to the synchronous pulley A103 through the flat key 102. The locking screw 107 is installed on the screw hole of the bearing seat 108. There are 4 locking screws 107. The die 1014 is installed inside the transmission shaft 104. There are 4 convex end locking screws 1010. 010 fixes the die 1014 inside the transmission shaft 104 to balance and stabilize the die 1014. Deep groove ball bearing 106 is installed on the bearing seat 108, and deep groove ball bearing 2 1011 is installed on the uppermost part of the transmission shaft 104. The two together bear the radial load when the transmission shaft 104 rotates and reduce the friction resistance. The plane bearing 109 is installed on the plane of the bearing seat 108, mainly bearing the axial load when the transmission shaft 104 rotates.

[0193] The locking screw 2 1013 is installed on the die flange 1012, and there are 4 locking screws 2 1013. The cone die flange 1015 is provided with 8 screw holes corresponding to the locking screw 2 1013 and the locking screw 3 1018. The die flange 1012 is connected to the screw holes on the cone die flange 1015 through the locking screw 2 1013. The bottom of the material cavity has a card interface (lower groove) with the cone die 1017. The inner cavity of the cone die 1017 has a certain cone angle, which is 20° or 30°. The inner cavity of the die 1014 corresponds to the cone angle of the inner cavity of the core die 1016. The cone die flange 1015 connects the inner cavity of the cone die 1017 with the material cavity of the extruder head through the locking screw 3 1018.

[0194] During the installation process, first install the deep groove ball bearing 106 on the bearing seat 108 through the spring retaining ring 105, and use the locking screw 107 to lock the mounting plate 1025, the bearing seat 108 and the die flange 1012. Then install the plane bearing 109, install the drive shaft 104 in the die flange 1012, and then install the deep groove ball bearing 2 1011. The three bearings and the drive shaft 104 form a unified whole. Then, install the cone die 1017 on the die flange 1012 and tighten it. The direction of rotation is from left to right. Use the locking screw 2 1013 to align the cone die flange 1017 with the die flange 1012. 15, clamp it and connect it, use flat key 102 to fix the synchronous pulley A103 and drive shaft 104, then place the PTFE blank tube 1019 (two-color circular blank) into the material cavity, align the cone die flange 1015 with the lower groove, and then use locking screw three 1018 to fix the cone die flange 1015. Finally, install the planetary reducer 1024 on the mounting plate 1025, install the synchronous pulley B1027 on the lower part of the planetary reducer 1024, connect the two pulleys with synchronous belt 1026, and connect the planetary reducer 1024 to the servo motor 1023. The drive device of vertical extruder 2 and servo motor 1023 are both connected to the power supply equipment.

[0195] In Examples 1-6, the step S3 is specifically as follows:

[0196] The two-color ring blank obtained in step S2 is put into the material cavity of extruder head, extruder head, cone die, rotatable die structure are connected in sequence, open the extrusion drive mechanism being connected with piston two in extruder head, extrusion drive mechanism applies pushing force to piston two, open servo motor 1023 simultaneously, adjust the gear of planetary reducer 1024, servo motor 1023 drives die to rotate by transmission shaft, therefore, the blank (also referred to as PTFE blank pipe 1019) in material cavity, is subject to the pushing force of piston two, enters the die in rotating state through cone die, and the pasty blank is passively stressed and rotates, obtains two-color spiral prefabricated pipe (also referred to as PTFE capillary 101) after pushing.The extrusion drive mechanism and servo motor 1023 of extruder two are all connected with power supply equipment.

[0197] Example 7:

[0198] In Example 7, except for the following contents such as step S25 which are different from those in Example 1-6, other steps are basically the same as those in Example 1-6.

[0199] Referring to Figures 14-15 , the two-color tube blank preparation apparatus in step S2 may further include a circular stopper 99 formed by joining two semicircular stoppers, and a stopper sleeve 9 detachably connected to the cylinder. Referring to Figures 16-18 , the stopper sleeve 9 includes a front end plate 91, a rear stopper ring 93, and an intermediate body 92 connecting the front end plate and the rear stopper ring. The front end plate, the rear stopper ring, and the intermediate body all have openings extending in the radial direction of the stopper sleeve. The width of the opening on the front end plate 91 is consistent with the outer diameter of the core rod 200, the width of the opening on the rear stopper ring 93 is consistent with the outer diameter of the annular groove 97, and the width of the opening on the intermediate body 92 is consistent with the outer diameter of the cylinder.

[0200] Step S25, referring to Figures 14-15 and Figures 8-13, two semicircular stoppers are inserted into the extrusion port of the cylinder 13 away from the first piston. The two semicircular stoppers surround the core rod 200 to form a circular stopper 99. The stopper sleeve 9 is inserted radially into the cylinder 13, with the front end plate 91 positioned at the extrusion end face of the cylinder 13 and the rear stopper ring 93 extending into the annular groove 97 on the cylinder. The hydraulic cylinder is activated, and the first piston moves within the cylinder 13 along the core rod 200, squeezing the tube toward the stoppers to obtain a further compacted tube. The two-color tube is uniform in color, and the intersection of the two colors is substantially parallel to the axis, providing a foundation for the later preparation of uniformly colored two-color spiral heat shrink tubing. The stopper sleeve 9 is then removed from the cylinder 13, and the stoppers are removed.

[0201] The core rod 200 in the extruder device 1 can be the same rod that is integrally connected to the core mold connecting rod 1028 in the extruder 2.

[0202] Connect the material chamber of the extruder 2 in step S3 to the extrusion end of the cylinder, start the hydraulic cylinder, and the piston 1 moves along the core rod in the cylinder to extrude the two-color circular tube blank from the cylinder 13 into the material chamber of the extruder 2, and carry out the subsequent polytetrafluoroethylene two-color spiral tube preparation process.

[0203] The color A mixture is prepared by uniformly mixing sieved polytetrafluoroethylene dispersion resin, extrusion aid oil, and color paste A in a certain proportion and curing them at a constant temperature to obtain the color A mixture; the color B mixture is prepared by uniformly mixing sieved polytetrafluoroethylene dispersion resin, extrusion aid oil, and color paste B in a certain proportion and curing them at a constant temperature to obtain the color B mixture.

[0204] The above-described embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that any modifications and improvements made by a person skilled in the art without departing from the spirit of the present application are within the scope of protection of the present application.

Claims

1. A method for preparing a polytetrafluoroethylene two-color spiral heat shrink tubing, characterized in that: The steps include: Step S1: A and B two-color mixing: Step S11: Place the sieved polytetrafluoroethylene dispersion resin into a dry and clean material barrel according to a certain proportion, add the extrusion aid oil and color paste A in sequence, mix well, and mature at a constant temperature to obtain color A mixed material; Step S12: Place the sieved polytetrafluoroethylene dispersion resin into a dry and clean material barrel according to a certain proportion, add extrusion aid oil and color paste B in sequence, mix well, and mature at a constant temperature to obtain color B mixed material; Step S2: Preforming of two-color blanks: The A-color mixed material and the B-color mixed material are respectively made into an A-color semi-circular tube blank and a B-color semi-circular tube blank, and the A-color semi-circular tube blank and the B-color semi-circular tube blank can be butted together to form a two-color circular tube blank; Step S3: Pushing and extruding: The color A semi-circular tube blank and the color B semi-circular tube blank obtained in step S2 are placed in the material cavity of the second extruder, the color A semi-circular tube blank and the color B semi-circular tube blank are butted together to form a two-color circular body, and the body is extruded through a die coaxial with the material cavity and rotating around the axis to obtain a two-color spiral prefabricated pipe; Step S4: drying, sintering, and cooling: The two-color spiral prefabricated pipe is dried, sintered, and naturally cooled in sequence to obtain a polytetrafluoroethylene two-color spiral pipe; Step S5: heat treatment: The polytetrafluoroethylene two-color spiral tube obtained in step S4 is heat-treated again; Step S6, inflation: After heat treatment, the polytetrafluoroethylene two-color spiral tube is quickly passed through the inflation machine to fill the compressed gas, and then cooled; Finally, a polytetrafluoroethylene two-color spiral heat shrink tubing was obtained; In the step S2, a two-color ring blank is prepared using a cylinder; The cylinder includes a cylinder body; the cylinder body is a semicircular ring, the side plane of the cylinder body is in contact with the inner surface of the partition, and arc-shaped flanges extending parallel to the axis of the cylinder body are provided on both sides of the partition, and the arc-shaped flanges are in contact with the arc surface of the cylinder body. A semi-cylinder coaxial with the cylinder body is provided on the inner surface of the partition, and a blocking plate is provided at one end in the axial direction of the cylinder body and the partition, and the blocking plate is used to block one end port of the internal space surrounded by the inner surface of the cylinder body, the inner surface of the partition, and the outer arc surface of the semi-cylinder; A pressure block is provided at the other end of the cylinder body and the partition in the axial direction. The pressure block is used to block the other end port of the internal space. The pressure block can move along the axial direction of the cylinder body under the action of external force to compress the mixture in the internal space. There are two cylinder bodies, which are respectively recorded as cylinder body 1 and cylinder body 2. When the side plane of cylinder body 1 is fitted with the side plane of cylinder body 2, a circular cylinder is formed. The step S2 is specifically as follows: Step S21: Assemble the cylinder body 1 and a partition together, with the side plane of the cylinder body 1 fitting against the inner surface of the partition, and add the color A mixed material into the internal space; use an auxiliary tool to apply a certain pressure to the color A mixed material so that the color A mixed material in the internal space is shaped into a color A semi-circular tube blank, remove the partition and the blocking plate, and the color A semi-circular tube blank is not loose; Step S22: Assemble the second cylinder body and a partition together, with the side plane of the second cylinder body fitting the inner surface of the partition, and add the color B mixed material into the internal space; use auxiliary tools to apply a certain pressure to the color B mixed material so that the color B mixed material in the internal space is shaped into a color B semi-circular tube blank, remove the partition and the blocking plate, and the color B semi-circular tube blank is not loose; Step S23: The cylinder body 1 containing the semi-circular tube blank of color A is butted and enclosed with the cylinder body containing the semi-circular tube blank of color B to obtain a circular cylinder containing a two-color circular tube blank, and the two-color circular tube blank is extruded from the circular cylinder by an extrusion device 1 to obtain a two-color circular tube blank; The extruder 2 in step S3 includes an extruder head, a core die, a cone die, and a rotatable die structure; The bottom of the extruder head is connected to the top of the core mold, the top of the cone mold is connected to the bottom of the extruder head, and the core mold is located in the inner cavity of the cone mold and the inner cavity of the mouth mold; The rotatable die structure includes a transmission shaft, a die flange, a die, and a rotation drive mechanism. The transmission shaft is rotatably arranged in the center hole of the die flange. A die receiving groove is provided on the top of the transmission shaft, and the die is connected to the die receiving groove. The rotation drive mechanism is in transmission connection with the transmission shaft to drive the transmission shaft and the die to rotate relative to the die flange. The bottom of the cone die is connected to the top of the die flange, and the bottom of the cone die and the top of the die are rotatably connected; The center line of the extruder head cavity, the center line of the cone die, the center line of the core die, the center line of the die and the center line of the drive shaft are located on the same straight line; The material cavity inside the extruder head, the inner cavity of the cone die, the inner cavity of the mouth die, and the center hole of the transmission shaft are connected in sequence; The step S3 is specifically as follows: The two-color circular ring blank obtained in step S2 is placed in the material cavity of the extruder head, and the extruder head, the cone die, and the rotatable die structure are connected in sequence. The extrusion drive mechanism connected to the second piston in the extruder head is turned on, and the extrusion drive mechanism applies a pushing force to the second piston. At the same time, the rotation drive mechanism is turned on, and the rotation drive mechanism drives the die to rotate through the transmission shaft. Therefore, the blank in the material cavity is subjected to the pushing force of the second piston, passes through the cone die and enters the die in a rotating state. The paste blank is passively subjected to force and rotates, and a two-color spiral prefabricated pipe is obtained after pushing.

2. The method for preparing a polytetrafluoroethylene two-color spiral heat shrink tubing according to claim 1, characterized in that: In the step S11, the aging temperature is 25-30°C, and the aging time is more than 12 hours; in the step S12, the aging temperature is 25-30°C, and the aging time is more than 12 hours.

3. The method for preparing a polytetrafluoroethylene two-color spiral heat shrink tubing according to claim 1, characterized in that: In the step S11, the weight ratio is: polytetrafluoroethylene dispersion resin accounts for 75-85%, and extrusion-aiding oil accounts for 15-25%; in the step S12, the weight ratio is: polytetrafluoroethylene dispersion resin accounts for 75-85%, and extrusion-aiding oil accounts for 15-25%.

4. The method for preparing a polytetrafluoroethylene two-color spiral heat shrink tubing according to claim 1, characterized in that: The color paste A or color paste B is a liquid color paste resistant to sintering temperature; the color paste A in step S11 is added in an amount of 0.2-1% of the total weight of the polytetrafluoroethylene dispersion resin and the extrusion-aiding oil; the color paste B in step S12 is added in an amount of 0.2-1% of the total weight of the polytetrafluoroethylene dispersion resin and the extrusion-aiding oil.

5. The method for preparing a polytetrafluoroethylene two-color spiral heat shrink tubing according to claim 1, characterized in that: In step S4, the drying temperature is 100° C., the sintering temperature is 380-450° C., and the sintering time is 20-40 seconds; in step S5, the heat treatment temperature is 360° C.; in step S6, after the heat treatment, the product is quickly passed through an inflation machine and filled with compressed gas below 0.98 MPa, with an inflation rate of 200%-400%, and then cooled.

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